Socket Fastener Removal Tool

Abstract

A device for rotating a work piece having a cavity includes a base with a polygonal opening for receiving a rotary tool to impart rotation to the base. A camshaft extends from the base and has jaws spaced around an axis. Each of the jaws has an outward facing drive surface configured to engage the cavity of the work piece and an inward facing cam surface in engagement by the camshaft. Each of the jaws has two side edges extending between the drive surface and the cam surface. Each of the side edges has an enter portion extending inward from the drive surface and an inner portion extending outward from the cam surface and joining the outer portion at an obtuse angle. A web of elastomeric material bonds to the inner and outer portions of each side edge and extends between adjacent ones of the jaws.

Description

FIELD

The invention is related to a fastener removal tool. More particularly, this invention relates to a tool for the removal of a socket fastener with a camshaft and cartridge.

BACKGROUND

A hex socket fastener is a type of fastener with a threaded cylindrical barrel that mates with a complementary thread in a fixture. The threads of a hex socket bolt may mate with the internal threads of a complementary nut to hold stack of parts together. Likewise, a hex socket head cap screw has a threaded cylindrical barrel that mates with the complementary threads in a fixture. The bolt and nut, or the screw and fixture, are kept together by a combination of thread friction and compression of the parts.

Hex socket screws and bolts are commonly known as ALLEN® screws and bolts, wherein ALLEN® is a U.S. trademark registered by Apex Brands, Inc., a Delaware corporation. Hex socket screws are thread on one side of a cylindrical screw for threading onto a complementary thread in a fixture or a nut. The opposite end of the screw is the head which has a smooth or knurled exterior surface and a hexagonal socket. Similarly, hex socket bolts have a cylindrical body with one end having threading for mating with a complementary nut, and the other end having a hexagonal socket. Hex socket screws and bolts are used when hexagonal or square screws or bolts will not fit; however, the interior corners or surfaces of the socket are vulnerable to being rounded off.

Hex socket screws and bolts are traditionally removed using hand wrenches, commonly known as ALLEN® wrenches, by applying force to one or more internal side faces or corners of the socket to cause it's rotation. However, where the internal side faces or corners of the socket have been stripped or damaged, or where the fastener has been corroded, it is very difficult and time consuming to remove such screws and bolts.

A former complication of screw and bolt removal using manual tools is that where the screw or bolt is very large, such as those used in oil production, manual removal using an ALLEN® wrench of such damaged screws and bolts presents danger to the operator, or manual removal is impossible because of the degree of torque required for removal.

One type of device accomplishes fastener removal by sawing off the fastener, or by using a blow torch to cut the fastener out of a fixture. However, these methods of removal result in damage to the screw or bolt, or the fixture. This problem may be solved with devices which either drill into the screw, or cut into the screw, so that torque can be applied to the screw for removal. However, these devices also result in further stripping and rounding of the screw, and the process of drilling a hole and subsequent removal is time-consuming.

Devices for the removal of hex socket fasteners using an air impact tool exist; however, in one such device, a cartridge having many small parts is used to apply torque to the damaged screw or bolt. These multiple small parts of the cartridge, such as multiple helical springs, studs and screws holding gripping jaws together are prone to breakage.

A further complication is that cartridges and other parts of removal tools are held within a cylindrical housing using a retaining ring or clip. The retaining ring or clip is prone to breakage, resulting in a damaged and useless tool.

Another complication of fastener removal using a hand-powered tool is side loading, or the mechanical binding of threaded surfaces against each other. When side loading occurs, heat builds up due to friction between the threaded surfaces, creating a gall which is carried through the housing, tearing out the threads, and actually impeding removal.

Yet another complication is “chattering”, where the tool does not perfectly conform to the size of the fastener. When rotative force is applied using an air impact tool, the removing tool “chatters” over the damaged corners of the fastener, further stripping the fastener, or damaging the tool interface with the fastener, causing ‘radii’ to form on the end of the tool.

A further problem is presented with a single device for fastener removal, because the device is limited in the size of fastener which can be removed with a single tool; that is, different sized fasteners cannot be removed with the same tool because the fastener heads cannot fit within the tool.

The use of a set of tools having a multiplicity of sizes to conform to different screw head sizes could solve the problem of imperfect conformance between the removal tool and fastener size. However, regardless of the size, the result is chattering from an imperfect size conformance; thus, stripping of the fastener socket occurs.

Further, the use of a set of tools having a multiplicity of sizes to conform to socket sizes presents another complication. If there exists a multiplicity of removal tool sizes in a set, the loss of one of the tools results in a useless tool set.

While the use of an air impact tool may eliminate much of the operator danger associated with hand wrenches, the use of an air impact tool presents a further problem. That is, the air impact tool itself creates a shock upon impact with the screw. When using sockets attached to air impact tools for screw removal, this shock impact can damage both the screw and adjacent surfaces. A further complication of some devices is that ridged teeth on the gripping surface of the jaws strip the screw socket.

It would thus be desirable to have a hex socket fastener removal tool that conforms to the size and shape of a multiplicity of sockets, where the jaws of the tool comprise one piece, rather than a multiplicity of smaller pieces which can be easily lost or damaged, and where the jaws are retained within a housing through a shock-absorbing canted coil spring.

SUMMARY

An apparatus for rotating a work piece having a cavity has a base having a first end with a polygonal opening for receiving a rotary tool to impart rotation to the base. A camshaft extends from a second end of the base along a longitudinal axis of the base for rotation with the base. The camshaft may be integrally formed with the base.

A plurality of jaws are spaced around the camshaft, each of the jaws having an outward facing drive surface configured to engage the cavity of the work piece and an inward facing cam surface in engagement by the camshaft. An increment of rotation of the base and the camshaft relative to the jaws causes the jaws to move radially outward into engagement with the cavity of the work piece. Each of the jaws has two side edges extending between the drive surface and the cam surface. Each of the side edges has an outer portion extending inward from the drive surface and an inner portion extending outward from the cam surface and joining the outer portion at an obtuse angle. A web of elastomeric material bonds to the inner and outer portions of each side edge and extends between adjacent ones of the jaws.

Preferably, an outer groove is located at an interface between the web and the outer portion of each of the side edges. An inner groove is located at an interface between the web and the inner portion of each of the side edges. The grooves in the preferred embodiment extend axially and are parallel with each other. Preferably, the grooves at located in the side edges of the jaws.

An inner portion line normal to the inner portion of each of the side edges may extend inward of the inner portion of the side edge of an adjacent one of the jaws. An outer portion line normal to the outer portion of each of the side edges may extend outward of the outer portion of an adjacent one of the jaws.

In the embodiment shown, the outer portion of each of the side edges is located in an outer portion plane. The inner portion of each of the side edges is located in an inner portion plane. The outer portion planes of adjacent ones of the jaws diverge from each other in an outward direction. The inner portion planes of adjacent ones of the jaws converge toward each other in an outward direction.

The cam surface of each of the jaws from one of the side edges to the other of the side edges may be configured at a single radius from the axis. In the embodiment shown, the camshaft comprises three curved lobes separated from each other by curved valleys; each of the lobes being formed at a single radius. Each of the valleys are formed at a single radius that is smaller than the radius of each of the lobes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows an exploded isometric view of the illustrative hex socket fastener removal tool.

FIG. 1B shows an exploded view of a canted coil spring.

FIG. 2A shows a canted coil spring wound in a clockwise direction about the coil centerline.

FIG. 2B shows a canted coil spring wound in a counterclockwise direction about the coil centerline.

FIG. 2C shows a canted coil spring with deflection and a graph of force and deflection.

FIG. 2D shows an illustrative knitted spring tube.

FIG. 3A shows a top view of the camshaft disposed within the camshaft base of the illustrative hex socket fastener removal tool, wherein the camshaft is not disposed within the cartridge.

FIG. 3B shows a bottom view of the illustrative hex socket fastener removal tool.

FIG. 4A shows a partial cross-sectional view of the camshaft disposed within the camshaft base of the hex socket fastener removal tool, without the cartridge or canted coil spring.

FIG. 4B shows a top view of the camshaft disposed within the camshaft base of the hex socket fastener removal tool without the cartridge or canted coil spring.

FIG. 5A shows a partial cross-sectional view of an illustrative cartridge without the canted coil spring.

FIG. 5B shows a top view of an illustrative cartridge.

FIG. 6A shows a top view of the illustrative camshaft disposed within the cartridge.

FIG. 6B shows a top view of the illustrative camshaft disposed within the cartridge, both positioned within an illustrative hex socket.

FIG. 7 is a perspective view of an alternate embodiment of the socket fastener removal tool.

FIG. 8 is an axial sectional view of the tool of FIG. 1.

FIG. 9 is a perspective view of the camshaft base and camshaft of the tool of FIG. 7 with the sleeve and cartridge removed.

FIG. 10 is a sectional view of the camshaft taken along the line 10-10 of FIG. 8 and with the sleeve and cartridge not shown.

FIG. 11 is a top view of the sleeve and cartridge of the tool of FIG. 7, with the camshaft not shown.

FIG. 12 is an enlarged top view of one of the jaws of the cartridge of FIG. 11.

FIG. 13 is a perspective view of the jaw of FIG. 12.

FIG. 14 is a sectional view of the sleeve and cartridge taken along the line 14-14 of FIG. 11.

DESCRIPTION

Persons of ordinary skill in the art will realize that the following description is illustrative and not in any way limiting. Other embodiments of the claimed subject matter will readily suggest themselves to such skilled persons having the benefit of this disclosure. It shall be appreciated by those of ordinary skill in the art that the apparatus and systems described herein may vary as to configuration and as to details. Additionally, the methods may vary as to details, order of the actions or other variations without departing from the illustrative method disclosed herein.

It is to be understood that the detailed description of illustrative embodiments provided for illustrative purposes. The scope of the claims is not limited to these specific embodiments or examples. Various structural limitations, elements, details, and uses can differ from those just described, or be expanded on or implemented using technologies not yet commercially viable, and yet still be within the inventive concepts of the present disclosure. The scope of the invention is determined by the following claims and their legal equivalents.

The apparatus described herein is generally applied to a socket fastener. Generally, a socket fastener includes a bolt and a head, in which the head has an aperture. The aperture on the head of the socket fastener is configured to receive a key or wrench, which can be used to tighten or loosen the socket fastener. By way of example and not of limitation, the illustrative socket faster described herein is referred to as a hex or ALLEN® socket. Note, the terms hex and ALLEN® may be used interchangeably in this description. The hex socket fastener removal tool described herein is used for the removal of a hex socket fastener such as an ALLEN® head cap screw, ALLEN® bolt or other socket fasteners from a nut or a fixture. Generally, the removal of the internal wrenching socket screw or bolt employs an impact wrench tool. Alternatively, other tools that provide needed torque may also be used.

For purposes of this patent, the terms “fastener” and “screw” will be used interchangeably. Additionally for the purposes of this patent, the terms “fastener” and “bolt” will be used interchangeably. A hex socket fastener is a cylindrical fastening device, usually of metal, having a threaded end and a head end. Hex socket fasteners are widely used for fastening machine and structural components, i.e. “machine screws”. The threaded end of the cylinder mates with complementary threads within a fixture or a nut. The opposite head of the cylinder has a wider diameter than the threaded end, and has a smooth or knurled surface on the sides of the head.

The head of the hex socket fastener includes a socket or aperture most commonly in the shape of a hexagon. Another illustrative hex socket may have twelve sides, known as a double hex socket. In addition to the standard hex socket fastener, there are other shapes for hex socket fasteners. In the illustrative embodiment presented herein, a hexagonal socket fastener is used; however, it shall be appreciated by those of ordinary skill in the art that other fastener geometries may be configured to interface with the hex socket fastener removal tool described herein, such as torx socket fasteners, security head sockets, pentalobular socket fasteners, or other such socket fasteners.

In the embodiments presented herein, an illustrative canted coil spring is used to engage a cartridge and sleeve assembly with a camshaft and camshaft base that receives a counterclockwise or clockwise force. The canted coil spring is presented as an illustrative spring technology that allows the cartridge to rotate freely; while ensuring that the cartridge does not slide out of the camshaft base. Alternatively, a knitted spring tube may also be used instead of the canted coil spring. The canted coil spring and the knitted spring tube may also be referred to as a seal preload device. Other spring technologies may also be used that allow the cartridge (which engages the socket of the screw) and the camshaft (which interfaces with the cartridge) to rotate freely in either a counterclockwise or clockwise direction, while at the same time ensuring that the camshaft base and camshaft do not slide out of the sleeve and cartridge assembly.

Additionally, the illustrative embodiment presented herein includes a three-lobed cam extending from the top surface of the camshaft, as described in further detail below. The three-lobed cam is configured to interface with the sleeve and cartridge assembly, which interfaces with the socket of a hex fastener. The three-lobed cam includes three lobes and three concave cam profiles. Each lobe of the illustrative three-lobed cam occupies a 120° arc and has a lobe centerline, a counterclockwise cam outer surface and a counterclockwise cam inner surface on one side of the lobe centerline, and a clockwise cam outer surface and a clockwise cam inner surface on the opposite side of the lobe centerline.

Generally, a counterclockwise force (to loosen the fastener) is applied to the polygonal shaped orifice in the camshaft base. This counterclockwise force is transferred from the camshaft to the cartridge when the cartridge interfaces with the counterclockwise cam surfaces of the camshaft. There may be instances when fastener removal requires the application of a clockwise force (tightening the screw), and then reverting back to the counterclockwise force.

The three-lobed cam described below is provided for illustrative purposes only. Alternatively, other lobed cam assemblies may also be used such as a two-lobed cam, a four-lobed cam, five-lobed cam, etc. The number of lobes and configuration of each lobe will depend on the particular socket.

Referring to FIG. 1A there is shown an illustrative hex socket fastener tool 10. The hex socket fastener removal tool includes a “base,” which will also be referred to as a camshaft base 30. The hex socket fastener removal tool also includes a camshaft 42, a canted coil spring 50 and a cartridge 70. The cartridge 70 is enclosed within a sleeve 60. The camshaft base 30 may be composed of a material having the appropriate tool steel grade or stainless steel grade. The camshaft base 30 may be manufactured by machining, utilizing a mold, or other such manufacturing techniques that are specific to tool manufacturing. The camshaft base 30 includes a bottom surface 37 (shown in FIGS. 3B and 4A) and a top surface 41. The camshaft bottom surface 37 may interface with a rotary tool such as an impact wrench.

A canted coil spring 50 rests within a groove 35 between the bottom surface 37 and the top surface 41 of the camshaft base 30. FIG. 1B presents an exploded view of the canted coil spring 50. More generally, the canted coil spring 50 may be referred to as a seal preload device. For example, another illustrative seal preload device is a knitted spring tube, as shown in FIG. 2D. The canted coil spring 50 engages the sleeve 60 to the camshaft base 30, while enabling the sleeve 60 to “float” on the camshaft base 30.

As shown in FIG. 1A, the canted coil spring 50 and the base 30 are configured to be received by the sleeve 60. The base 30 and the camshaft 42 are shown in further detail in FIGS. 3A, 3B, 4A and 4B presented hereinafter. The sleeve 60 and cartridge 70 are described in further detail at FIGS. 5A, 5B, 6A, and 68 hereinafter. The illustrative bottom surface 37 of the camshaft base 30 receives an illustrative O-ring 20, which is configured to interface with an illustrative impact wrench (not shown). Alternatively, the O-ring 20 may be replaced with a second canted coil spring. Further detail regarding the bottom surface 37 of the camshaft base 30 is presented in FIG. 3B, which shows a bottom view of the camshaft base bottom surface 37.

In the illustrative embodiment, the camshaft base bottom surface 37 is configured to receive an impact rotary tool. The camshaft base 30 may further include a slot 82 configured to receive a pin 80 that is inserted within the slot 82 when the camshaft base 30 is configured to interface with a rotary tool. The pin 80 holds the rotary tool in place.

More generally, the socket fastener removal tool 10 includes a fastening component with a biasing element that is configured to allow the sleeve 60 and cartridge 70 and the camshaft base 30 and camshaft 42 to rotate freely in a counterclockwise or clockwise direction, and also enable the camshaft base 30 to stay within the sleeve 60 during fastener removal and tightening operations. The illustrative fastening component with the biasing element presented herein includes seal preload device such as a canted coil spring 50.

The illustrative embodiment may include one of two types of canted coil springs, as shown in FIGS. 2A and 2B. The first type of canted coil spring 51 presented in FIG. 2A has the coils wound in a clockwise direction about the coil centerline 53 as indicated by arrow 52. The second type of canted coil spring 54 is shown in FIG. 2B, and has the coils wound in a counterclockwise direction about the coil centerline 56 as indicated by arrow 55. The illustrative canted coil spring 50 may have the coils canted in either a clockwise or counterclockwise depending on the particular application and design constraints.

Referring now to FIG. 2C, there is shown side view of a canted coil spring 50 subject to deflection from an axial load. An axial canted coil spring has its compression force 57 parallel or axial to the centerline of the arc or ring. The graph of force vs. deflection shows the canted coil spring 50 being subjected to a range of compressive (axial) forces. As more force 57 is applied to the canted coil spring 50, the angle between the coils and the vertical axis increases. In the “normal deflection” range shown in FIG. 2C, the normal deflection indicates that the force produced by a canted coil spring 50 is nearly constant over a long range of deflection, especially when compared to a typical spring. This enables the sleeve 60 to “float” on the canted coil spring 50.

As described in further detail below, the canted coil spring 50 is installed within grooves in both the camshaft base 30 and the sleeve 60. The canted coil spring design may be designed according to the following illustrative parameters, namely, the wire material, the wire diameter, the cant amplitude, the coils per inch, the size controlled by spring width, and eccentricity. The cant amplitude is the axial distance the top coil is shifted compared to a helical spring. The eccentricity is a parameter that indicates a circular cross section; as the eccentricity increases the spring becomes more elliptical. Some manufacturers use other parameters to design a canted coil spring such as the front angle and the back angle instead of coils per inch and cant amplitude.

When a canted coil spring is deformed, the top of the coils slide against the contact surface and the bottom coils rotate about their axis. For example, the bottom of the spring is constrained axially so the coefficient of friction is greater at the contact between the spring and the bottom surface than the spring and the top surface; this process enables the cage to “float” on the canted coil spring.

Another illustrative seal preload device is a knitted spring tube shown in FIG. 2D. The knitted spring tube 58 includes a series of needles interwoven about a base helix. The needle pattern is defined by the combination of a circular section and a linear section, in which both sections are piecewise continuous and smooth at their intersection. Other parameters to consider for designing canted coil springs and knitted spring tubes are provided in the thesis entitled “MODELING OF CANTED COIL SPRINGS AND KNITTED SPRING TUBES AS HIGH TEMPERATURE SEAL PRELOAD DEVICES,” by Jay J. Oswald submitted in May 2005.

Referring now to FIG. 3A and FIG. 4B, there is shown an illustrative a top view and a cross-sectional view, respectively, of the camshaft base 30 and the camshaft 42 having a three-lobed cam. The camshaft base includes a top surface 41, a top section 38, a first shoulder 34, a second shoulder 39, a bottom section 32 and a groove 35 that the canted coil spring 50 interfaces with.

Referring now to FIG. 3B, there is shown an illustrative bottom view of the bottom surface 37. A rotary power tool is configured to slidably couple with the polygon shaped opening 31. Alternatively, a second canted coil spring may be used instead of the O-ring 20. The second canted coil spring can also absorb additional axial loading, thus enabling the cage to effectively grip the stud with minimal interference from the compressive forces emanating from the rotary power tool.

The illustrative rotary power tool may be an impact wrench having an anvil (not shown) configured to be received by a polygon shaped opening 31 at the bottom surface 37 of the hex socket fastener removal tool 10. Although the opening is shown as being square shaped, a circular or elliptical shaped opening may also be configured to match the shape of the rotary power tool.

An impact wrench is a power tool that delivers a high torque output by storing energy in a rotating mass and then delivering the energy to the output shaft. The power source for an impact wrench is generally compressed air. When a hammer, i.e. rotating mass, is accelerated by the power source and then connected to an anvil, i.e. output shaft, this creates the high-torque impact. When the hammer spins, the hammer's momentum is used to store kinetic energy that is then delivered to the anvil in a theoretically elastic collision having a very short impact force.

With an impact wrench, the only reaction force applied to the body of the tool is the motor accelerating the hammer, and thus the operator feels very little torque, even though a very high peak torque is delivered to the anvil. The impact wrench delivers rotational forces that can be switched between counterclockwise rotation and clockwise rotation. Additionally, the impact wrenches deliver oscillating compressive forces along the axis of the anvil of the impact wrench. Thus, when removing a fastener, the anvil of the impact wrench is typically along a vertical axis and the impact wrench delivers oscillating compressive forces along the axis of the anvil, i.e. axial load, and rotational forces.

Referring now to FIG. 4A, where there is shown a cross-sectional view of the camshaft base 30 and the camshaft 42. An interior sidewall 48 extends from the camshaft base top surface 41 to a camshaft interface 49. By way of example and not of limitation, the cam interior sidewall 48 includes three cam interior side-wall lobes. The cam interior sidewall lobes are equidistant from each other so that the are occupied by each lobe is each approximately 120°. The cam interior sidewall 48 is configured to interface with the camshaft 42, which interfaces with the cartridge 70 (shown in FIGS. 1A, 5 and 6).

The camshaft base 30 includes a top section 38 between the base top surface 41 and the first shoulder 34. The top section 38 includes a first camshaft groove 35 that is configured to receive the canted coil spring 50. The first camshaft groove 35 extends around the exterior perimeter of the camshaft base 30. The camshaft base 30 also includes a middle section 36 disposed between the first shoulder 34 and a second shoulder 39.

The camshaft base 30 further includes a bottom section 32 which extends from the second shoulder 39 to the bottom surface 37. The camshaft bottom end 32 may also include a slot 82 for receiving the pin 80 (shown in FIG. 1A). The camshaft bottom section 32 further includes a polygon-shaped shaped opening 31 in the bottom surface 37 for interfacing with the impact wrench. By way of example and not of limitation, the polygon shaped opening 31 is sized proportionate to the size of the impact wrench, such as ¼″, ⅜″, ½″, ¾″, 1″, 1½″, 2½″, 3½″ drive impact wrenches. Additionally, a second camshaft groove 33 receives illustrative O-ring 20 (shown in FIG. 1A).

Referring now to FIG. 4B, there is shown the camshaft 42. The camshaft 42 includes three lobes 88 that each has a lobe centerline 86. Each lobe 88 has a distal portion 87 along the lobe centerline 86 that is furthest from the center of the camshaft 42. Additionally, each lobe 88 includes three counterclockwise convex cam interfaces 44 on one side of each lobe centerline 86, and three clockwise cam interfaces 46 on the opposite side of the lobe centerline 86. Between the lobes 88, there is a concave cam interface 45.

The illustrative lobe centerlines 86 are 120° apart from each other. Each counterclockwise convex cam interface 44 occupies a 30° arc. Each clockwise convex cam interface 46 occupies a 30° arc, and each concave cam interface 45 occupies a 60° arc.

In the illustrative embodiment presented in FIG. 4B, the distance between the distal portion of the lobe 87 and the center of the camshaft 42 is greater than the semi-circular radius used to form the counterclockwise convex cam interface 44 and the clockwise convex cam interface 46. In the illustrative embodiment shown in FIG. 4B, the semi-circular radius used to form the counterclockwise convex cam interfaces 44, and the clockwise convex cam interface 46 share the same center radius. Alternatively, the semi-circular radius used to form the counterclockwise cam interfaces 44, and the clockwise convex cam interfaces 46 may each have a different center radios.

Referring back to FIG. 4A, the camshaft 42 includes a top surface 43 and a bottom surface 47. As shown in FIG. 4B, the camshaft 42 further includes three counterclockwise convex cam interfaces 44, three clockwise convex cam interfaces 46, and three concave cam interfaces 45. The counterclockwise convex cam interfaces 44, clockwise convex cam interfaces 46 and concave cam interfaces 45 all extend from the camshaft top surface 43 to the camshaft bottom surface 47.

The camshaft 42 is fixedly coupled to the camshaft base interior sidewall 48 and the camshaft interface 49. By way of example and not of limitation, the camshaft 42 is constructed of heat treated S7 steel that measures 52-54 on the Rockwell C scale, as measured with a Hardness Tester, such as that described in U.S. Pat. No. 1,294,171, “HARDNESS TESTER,” Hugh M. Rockwell and Stanley P. Rockwell, issued Feb. 11, 1919. S7 steel is a shock-resistant, air-hardening steel used for tools, and which is designed for high impact resistance at relatively high hardness in order to withstand chipping and breaking. In an alternative embodiment, H-13 steel is used, measuring 44-46 on the Rockwell C scale. Other alloys may also be used. Steels used are not plated or coated, other than surface treatment to produce a black oxide finish for corrosion resistance.

Generally, a counterclockwise force (to loosen the hex socket fastener) is applied to the camshaft base 30 for fastener removal. This counterclockwise force is transferred to the camshaft 42, which transfers force to the sleeve and cartridge assembly, which interfaces with the counterclockwise convex cam interface 44. There may be instances when fastener removal requires the application of a clockwise force (tightening the fastener) so the camshaft base 30 is turned in a clockwise direction and this force is then transferred to the camshaft 42, the cartridge assembly 70, and the clockwise convex cam interface 46. An illustrative impact wrench may be employed that has an operator-controlled switch that can switch the direction of the force applied to the nut removal tool from counterclockwise, to clockwise, and back to counterclockwise. By performing this operation of oscillating between the counterclockwise and clockwise directions, additional torque may be transferred to the nut to more effectively remove the nut.

The illustrative six-lobed cam 42 is symmetrical and is presented for illustrative purposes only. Alternatively, other symmetrical lobed cam assemblies may also be used such as a two-lobed cam, a four-lobed cam, five-lobed cam, etc. The number of lobes, size of lobes, and configuration of each lobe will depend on the particular application.

Additionally, each lobe may have more than just two symmetrical cam surfaces (i.e. clockwise inner cam surface and counterclockwise inner cam surface). For example, each lobe may have three, four, five or six different cam inner surfaces that can interface with different cages or cartridges.

Furthermore, asymmetrical cam inner surfaces may also be employed. Thus, the lobed cam inner surface may have additional surfaces beyond just the symmetrical three-lobed cam surface presented herein. The inner cam surface may be asymmetrical and include a plurality of surfaces that can interface with a plurality of different cartridges.

Referring now to FIG. 5A there is shown a side view of the illustrative sleeve 60 and cartridge 70 assembly. The cartridge 70 is configured to interface with the camshaft 42. The sleeve 60 is configured to interface with the canted coil spring 50 and the camshaft base 30. The cartridge 70 includes a top surface 78, three jaws 71, an elastic component 74 and an elastic lip 64. The elastic component 74 includes an exterior sidewall 63 and an interior sidewall 65. The exterior sidewall 63 of the elastic component 74 extends from the top surface 78 to a cartridge shoulder 61. The interior sidewall 65 of the elastic component 74 extends from the top surface 78 to the elastic lip 64.

The sleeve 60 includes a sleeve lip 66, a sleeve interior sidewall 69 and a sleeve bottom surface 68. The sleeve lip 66 extends around the perimeter of the sleeve 60. The sleeve interior sidewall 69 defines an orifice in the sleeve 60 which extends from the sleeve lip 66 to the sleeve bottom surface 68. Additionally, the sleeve 60 has a sleeve groove 62 that is disposed between the sleeve lip 66 and the sleeve bottom surface 68. The sleeve groove 62 interfaces with the canted coil spring 50.

The cartridge shoulder 61 is fixedly coupled to the jaws 71 and to the interior sidewall 69 of the sleeve 60. By way of example and not of limitation, the elastic component 74 is bonded to the interior sidewall 69 and the jaws 71 using illustrative 30 durometer urethane rubber or other bonding material which is capable of withstanding the operating conditions of fastener removal. Additionally, the elastic component must be able to flex independent of the jaws and sleeve in a lateral direction.

Referring now to FIG. 5B, there is shown a top view of the illustrative cartridge 70. The cartridge includes a plurality of jaws 71a, 71b, and 71c. Each of the jaws 71a, 71b and 71c, includes a jaw centerline 75a, 75b and 75c, respectively. Each jaw centerline 75 is 120° from the other jaw centerlines. Each jaw 71 has a distal portion 79 along the jaw centerline 75 that is furthest from the center of the cartridge 70.

Each of the jaws 71a, 71b and 71c includes a jaw outer counterclockwise cam surface 72a, 72b and 72c on one side of the jaw centerline 75a, 75b and 75c, respectively, and a jaw outer clockwise cam outer surface 73a, 73b and 73c on the opposite side of the jaw centerline 75a, 75b and 75c, respectively. Each jaw also includes a jaw inner counterclockwise cam surface 77 on one side of the jaw centerline 75, and a jaw inner clockwise cam surface 76 on the opposite side of the jaw centerline 75. Each jaw 71 abuts a portion of the elastic component 74, winch separates the jaws and holds the jaws in place within the cartridge.

The illustrative three jaw cam outer surfaces include six different cam outer surfaces, in which three jaw cam outer surfaces are clockwise cam surfaces and three cam outer surfaces are counterclockwise cam surfaces. Likewise, the illustrative three jaw cam inner surfaces include six different cam inner surfaces, in which three jaw cam inner surfaces are clockwise cam surfaces and three cam inner surfaces are counterclockwise cam surfaces. In the illustrative embodiment, each jaw counterclockwise outer cam surface 72 and jaw clockwise outer cam surface 73 occupies a 30° arc. The jaw counterclockwise cam inner surface 77 is configured to interface with the convex counterclockwise can interface 44 (shown in FIG. 4A). The jaw clockwise cam inner surface 76 is configured to interface with the convex clockwise cam interface 46 (shown in FIG. 4A).

For the purposes of this patent, the terms “elastic component” and “webbing” are used interchangeably. The illustrative cartridge 70 also includes the illustrative elastic component 74a that joins jaws 71a and 71b. Also, elastic component 74b joins jaws 71b and 71c. Additionally, webbing 74c joins jaws 71a and 71c. The webbing may also be embodied as an injection molded elastomeric cartridge or cage. By way of example and not of limitation, the elastomeric component configured to join the jaws has a durometer ranging from 20-40. In a narrower embodiment, the elastomeric material has a durometer of 30. By way of example and not limitation, the elastic material is a 1500 psi injection molded rubber.

Generally, the webbing material is composed of an elastic material that can withstand operating conditions for fastener removal. For example, the webbing matter may be composed of an elastic thermoplastic resin that is resistant to petroleum products. Also, other elastic or elastomeric materials such as rubber or neoprene may also be used.

The webbing 74 presses the jaws 71 firmly against the surfaces of the cam interfaces 44, 45 and 46. Further, the webbing 74 between the jaws 71 maintains symmetry between the jaws 71, and in conjunction with the sleeve 60, forms a stable cartridge assembly.

Referring now to FIG. 1A, FIG. 4A and FIG. 5A, when inserted into the sleeve 60, the camshaft base 30 slidably engages with the sleeve interior sidewall 69, and the camshaft 42 slidably engages with the cartridge jaws 71 and the interior sidewall 65 of the elastic component 74. Further, the top section 38 of the camshaft base 30 slides past the canted coil spring 50 fitted within the sleeve groove 62, and the canted coil spring 50 is received by the first camshaft groove 35. The top surface 41 of the camshaft base 30 interfaces with the elastic lip 64 of the sleeve 60. The sleeve bottom surface 68 interfaces with the first shoulder 34 of the camshaft base 30. When the canted coil spring 50 is secured within both the sleeve groove 62 and the first camshaft groove 35, the camshaft base 30 latches within the sleeve 60 with the canted coil spring 50, holding the camshaft base 30 in place within the sleeve 60.

Referring now to FIG. 6A there is shown a sectional top view of the cartridge 70 of the hexagonal socket fastener removal tool 10 with the camshaft 42 within the cartridge 70. In FIG. 6A, the jaws 71a, 71b and 71c are shown in a resting position, in which no force is applied to the camshaft 42. In this resting position, the jaws 71 are not engaging the fastener and the elastic webbing 74 used to join the jaws 71 causes the jaws 71 to remain in the resting position shown in FIG. 6A. In this resting position the hexagonal socket fastener removal tool 10 is capable of accepting the fastener 90 before a rotational force is applied to the fastener 90 (shown in FIG. 6B). The camshaft 42 includes three convex counterclockwise lobe interfaces, 44a, 44b and 44c. Additionally, the camshaft 42 includes three clockwise convex lobe interfaces 46a, 46b and 46c. Each jaw 71 has three counterclockwise jaw cam outer surfaces 72a, 72b and 72c, and three clockwise jaw outer cam surfaces, 73a, 73b and 73c. Further each jaw 71 has three counterclockwise cam inner surfaces 77a, 77b and 77c, and each jaw 71 has three clockwise cam inner surfaces 76a, 76b and 76c.

Referring now FIG. 6B, when counterclockwise force is applied to the camshaft base 30 (shown in FIGS. 1A, 3A, 4A), this causes the camshaft 42 to shift approximately 30° to the left and the jaws 71 are biased radially outwards by the camshaft 42. When the camshaft 42 is rotated counterclockwise by a rotary power source, such as the air impact wrench described above, this counterclockwise force causes the convex counterclockwise lobe interface 44 to engage with the counterclockwise jaw cam inner surface 77. When the jaws are biased radially outwards by the camshaft 42, and the effective circumference of the cartridge is enlarged, this causes the elastic webbing 74 to flex. When the jaws 71 are biased radially outwards, the jaw cam outer counterclockwise surfaces 72a, 72b and 72c engage three of the counterclockwise flat surfaces of the hexagonal socket 92a, 92b and 92c, respectively. The counterclockwise force is applied in a 30° arc along the three counterclockwise hexagonal socket surfaces 92a, 92b and 92c, applying force along 90° of the hexagonal socket, rotating the fastener counterclockwise for removing the fastener.

More specifically, the hexagonal socket fastener removal tool is configured to turn in a counterclockwise manner. This rotation causes the camshaft counterclockwise convex cam surfaces, 44a, 44b and 44c to apply force to the jaw counterclockwise cam inner surfaces 77a, 77b and 77c, respectively. In operation, the deformation of the elastic component 74 upon the application of torque allows for the jaw counterclockwise cam outer surface 72a, 72b and 72c to contact the fastener socket 90 at multiple contact points. During counterclockwise rotation, each jaw counterclockwise cam outer surfaces 72a, 72b and 72c contacts 30° of each of the socket inner surface 92a, 92b and 92c respectively, of the flat counterclockwise surface of the socket fastener, allowing for 90° of contact. Thus, upon counterclockwise rotation, 25% of the surfaces of the socket of the fastener are in contact with the hex socket fastener removal tool.

There may be instances when fastener removal requires the application of a clockwise force (tightening the nut) so the camshaft base 30 is turned in a clockwise direction. When this clockwise force is applied to the camshaft base 30, this causes the camshaft to shift approximately 30° to the right and the jaws are biased radially outwards by the cam. When the camshaft 42 is rotated clockwise by a rotary power source, such as the air impact wrench described above, this clockwise force causes the convex clockwise lobe interface 46 to engage with the clockwise jaw cam inner surface 76. When the jaws 71 are biased radially outwards by the camshaft 42, and the effective circumference of the cartridge is enlarged, this causes the elastic webbing 74 to flex. When the jaws 71 are biased radially outwards, the jaw cam outer clockwise surfaces 73a, 73b and 73c engage three of the clockwise flat surfaces of the hexagonal socket 94a, 94b and 94c. The clockwise force is applied in a 30° arc along the three clockwise hexagonal socket surfaces 94a, 94b and 94c, applying force along 90° of the hexagonal socket rotating the fastener clockwise for tightening the faster.

More specifically, when the hexagonal socket fastener removal tool is configured to turn in a clockwise manner, this rotation causes the camshaft clockwise convex cam surfaces, 46 to apply force to the jaw clockwise cam inner surfaces 76. In operation, the deformation of the elastic component 74 upon the application of torque allows for the jaw clockwise cam outer surfaces 73a, 73b and 73c, respectively, to contact the fastener socket 90 at multiple contact points. Daring clockwise rotation, each jaw clockwise cam outer surface 73a, 73b and 73c contacts 30° of the socket inner surface 94a, 94b and 94c, respectively, of the flat clockwise surface of the socket fastener, allowing for 90° of contact, or 25% of the surfaces of the fastener.

Additionally, during fastener removal, the operator may increase the amount torque applied to the fastener by toggling between applying a counterclockwise force and a clockwise force using the hexagonal socket removal assembly described herein.

The illustrative jaw outer cam surface 71 having three jaws is symmetrical and is presented for illustrative purposes only. Alternatively, other symmetrical jaw inner cam assemblies may also be used such as an assembly having two jaws, four jaws, five jaws, etc. The number of jaws and configuration of each jaw will depend on the particular application.

Additionally, each jaw may have more than just two symmetrical cam surfaces (i.e. clockwise outer cam surface and counterclockwise outer cam surface). For example, each jaw may have three, four, five or six different cam outer surfaces that can interface with different shaped fastener sockets.

Furthermore, asymmetrical jaw cam outer surfaces may also be employed. Thus, the jaw cam outer surface may have additional surfaces beyond just the symmetrical three jaw cam surface presented herein. The jaw outer can surface may be asymmetrical and include a plurality of surfaces that can interface with a plurality of different fastener socket shapes.

Alternatively, the hexagonal socket fastener removal apparatus 10 described above may not require a canted coil spring 50 or other such seal preload device.

Referring to FIG. 7, an alternate embodiment tool 101 has a base 103, a sleeve 105, a cartridge 107, and a camshaft 109. Tool 101 operates in the same manner as the first embodiment. As shown in FIG. 8, base 103 has a longitudinal axis 110 and a first end or bottom 111, which also may be referred for convenience only as a lower end. Tool 101 can be operated with axis 110 in any orientation. A polygonal opening 113 on axis 110 extends into bottom 113. Opening 113 is typically square for receiving the drive member of a rotary tool (not shown) to impart rotation to base 103. Base 103 has an upper portion with a large diameter, upward facing external shoulder 115. Base 103 has a smaller diameter upward facing external shoulder 117 above larger diameter shoulder 115 that defines an upper or second end of base 103. Cam shaft 109 extends axially upward from smaller diameter shoulder 117. In this embodiment, cam shaft 109 is integrally formed with base 103 from the same piece of metal.

The cylindrical portion of base 103 between shoulders 115, 117 has an annular external groove 119. Sleeve 105 has an annular internal groove 121 dial axially aligns with external groove 119. A spring 123 locates in mating grooves 119, 121. Spring 123, which is preferably a canted spring similar to spring 50 (FIG. 1B), retains sleeve 105 on base 103 but allows limited rotation of base 103 relative to sleeve 105. Cartridge 107 is bonded to and extends upward from sleeve 105 around camshaft 109.

Referring to FIG. 9, in this embodiment camshaft 109 has three lobes 125 with a recess or valley 127 located between adjacent lobes 125. Lobes 125 and valleys 127 are rounded, curved exterior surfaces extending the length of camshaft 109. As shown in FIG. 10, each lobe 125 has a centerline 129 extending from axis 110 to a lobe midpoint 130. Centerlines 129 are spaced 120 degrees apart. Each lobe 125 is symmetrical about its midpoint 130. In this example, each lobe 125 is formed with a single radius 131 that extends from a lobe radial center point 133 spaced from axis 110. Lobe radius 131 has a smaller length than lobe centerline 129. Each lobe 125 extends along lobe radius 131 from transitions or junctions with adjacent valleys 127. The circumferential length of lobe 125 at lobe radius 131 front one valley 127 to the other may be about 180 degrees, but that can vary.

Each recess or valley 127 is also formed about a single radius 137 from a single valley radial center point 139. Valley radius 137 extends between transitions or junctions with two adjacent lobes 125. The circumferential extent of each valley 127 along valley radius 137 is about 60 degrees in this example, but that can vary. Valley radius 137 is considerably smaller than lobe radius 131. Each valley 127 is also symmetrical about a centerline 141 emanating from axis 110. Valley centerlines 141 are spaced 120 degrees apart in this embodiment. The length of valley centerline 141 is less than the length of lobe centerline 129. The length of valley centerline 141 is preferably in a range from 60% to 80% of the length of lobe centerline 129; in this example, valley centerline 141 has a length about 65% the length of lobe centerline 129.

Referring to FIG. 11, cartridge 107 has a plurality of jaws 143, three in this example. Each jaw 143 is a rigid member, preferably metal, with an outward facing drive surface 145 relative to axis 110. Drive surface 145 is configured to engage a cavity of a work piece to impart rotation to the work piece. The work piece may be fastener 90 (FIG. 6B), which has a cavity with a polygonal sidewall containing drive flats 92a, 92b, 92c, and 94a, 94b, 94c. To drive fastener 90, jaw drive surface 145 has two flat surfaces 145a, 145b that join each other at a corner 145c. With three jaws 143, the angle of intersection between flat surfaces 145a, 145b is 120 degrees. Jaw drive surface 145 is symmetrical about corner 145c.

Each jaw 143 has in inward facing curved cam surface 147. In this embodiment, jaw cam surface 147 is formed at a single radius 149 about a jaw radial center point 151 spaced from axis 110. Jaw cam surface 147 extends circumferentially at radius 148 for about 120 degrees. In this example, jaw center point 151 coincides with lobe centerpoint 133 (FIG. 10), and jaw radius 149 has the same length as lobe radius 131. When camshaft 109 (FIG. 10) is located within cartridge 107 and cartridge 107 in a relaxed position, lobes 125 (FIG. 10) will be in flush contact with jaw cam surfaces 147 and lobe centerlines 129 will align with jaw centerlines, which pass from axis 110 through corners 145c.

Each jaw 143 has two side edges 153 extending from drive surface 145 to cam surface 147. A web portion 155 of a cylindrical elastomeric shell 157 bonds adjacent jaws 143 to each other at side edges 153. Web portions 155 are flexible, enabling jaws 143 to move radially outward from the relaxed position to an engaged position when camshaft 109 (FIG. 10) rotates an increment relative to cartridge 107.

Referring to FIG. 12, the portion of each jaw 143 at each side edge 153 flares outward in width. More specifically, each jaw side edge 153 has an outer portion 159 and an inner portion 161. Outer portion 159 extends inward front drive surface 145, and inner portion 161 extends outward from cam surface 147. Outer and inner portions 159, 161 join each other midway between cam surface 147 and drive surface 145. Inner and outer portions 161, 159 intersect each other at an obtuse angle 163 that is about 220 degrees, but that may vary. Outer portion 159 may be at a 90 degree angle relative to the drive surface 145b that it joins.

In this example, inner and outer portions 161, 159 are flat, but they could be rounded into a continuous curved surface from drive surface 145 to cam surface 147. Outer portion 159 lies in an outer portion plane 165, and inner portion 161 lies in an inner portion plane 167. Inner portion plane 167 intersects cam surface radial center point 151 in this example. Outer portion plane 165 does not intersect either axis 110 (FIG. 11) or cam surface radial center point 151. Inner portion plane 167 of one side edge 153 intersects the inner portion plane 167 of the other side edge 153 of the same jaw 143 at an angle 168 that may vary and is shown to be about 130 degrees. Outer portion plane 165 of one side edge 153 intersects the outer portion plane 165 of the other side edge 153 of the same jaw 143 at an intersection point (not shown) that is farther from outer portion 159 than axis 110 (FIG. 11).

As illustrated in FIG. 11, outer portion plane 165 of side edge 153 of one jaw 143 and outer portion plane 165 of the closest jaw side edge 153 of an adjacent jaw 143 diverge from each other in an outward direction. Inner portion plane 167 of one jaw 143 and inner portion plane 167 of the closest jaw side edge 153 of an adjacent jaw 143 converge toward each other in an outward direction.

Referring again to FIG. 12, a line 169 normal to outer portion plane 165 points generally parallel with the adjoining drive surface 145b. A line 171 normal to inner portion plane 167 diverges from outer portion normal line 169. Inner portion normal line 171 at the intersection between inner portion 161 and cam surface 147 is a tangent line to cam surface 147 at the intersection. As shown in FIG. 11, outer portion normal line 169 at the junction with drive surface 145 points outward of side edge 153 of the adjacent jaw 143. Inner portion normal line 171 at the intersection with cam surface 147 points inward of side edge 153 of the adjacent jaw 143.

Referring still to FIG 12, each side edge 153 preferably has at least one groove 173 to enhance bonding to web portion 157 (FIG. 11). In the preferred embodiment, two grooves 173 are employed, one in outer portion 159 and one in inner portion 161. Each groove 173 extends the axial length of each jaw 143, as illustrated in FIG. 13. Alternately, one or more grooves could be located within web portions 155 (FIG. 11), and axially extending ribs could be formed on side edges 153.

Referring to FIG. 14, in addition to the bonding of jaw side edges 153 to web portions 155 (FIG. 11), each jaw 143 has a lower edge bonded to a lower edge of a rectangular slot 175 formed in elastomeric shell 157. Each jaw 143 locates within slot 175. A groove may be located in in the lower edge of each jaw 143, as shown, to assist in bonding. Elastomeric shell 157 has a lower cylindrical or internal portion 177 that inserts into and is bonded to a bore of sleeve 105. Lower cylindrical portion 177 has a smaller order diameter than the diameter of the external portion of elastomeric shell 157, which protrudes above sleeve 105. The external portion of elastomeric shell 157 is fully cylindrical between the upper end of sleeve 105 and the lower edges of jaws 143. A downward facing shoulder 179 of shell 157 overlies and may be bonded to the upper end of sleeve 105. The axial length of each jaw 143 is less than an axial dimension of the external portion of elastomeric shell 157 from the upper end of shell 157 to the upper end of sleeve 105.

During operation of the embodiment of FIGS. 7-14, a technician will insert an impact tool drive member into base opening 113 and insert cartridge 107 into the polygonal cavity of fastener 90. Operating the tool causes base 103 and camshaft 109 to rotate. Sleeve 105 and cartridge 107 do not rotate in unison with camshaft 109 for an initial increment, which causes one-half of each lobe 125 to rotationally slide an increment along one-half of each jaw 143. The sliding movement of lobes 125 pushes jaws 143 radially outward into engagement with either fastener drive flat portions 92a, 92b, 92c or 94a, 94b, 94c, depending on whether the rotation is clockwise or counterclockwise. Continued rotation of base 103 causes cartridge 107 to rotate in unison, either unscrewing or tightening fastener 90.

It is to be understood that the detailed description of illustrative embodiments provided for illustrative purposes. The scope of the claims is not limited to these specific embodiments or examples. Various structural limitations, elements, details, and uses can differ from those just described, or be expanded on or implemented using technologies not yet commercially viable, and yet still be within the inventive concepts of the present disclosure. The scope of the invention is determined by the following claims and their legal equivalents.

Claims

1. An apparatus for rotating a work piece having a cavity, comprising:

a base having a first end with a polygonal opening for receiving a rotary tool to impart rotation to the base;

a camshaft extending from a second end of the base along a longitudinal axis of the base for rotation with the base;

a plurality of jaws spaced around the camshaft, each of the jaws having an outward facing drive surface configured to engage the cavity of the work piece and an inward facing cam surface in engagement by the camshaft, wherein an increment of rotation of the base and the camshaft relative to the jaws causes the jaws to move radially outward into engagement with the cavity of the work piece;

each of the jaws having two side edges extending between the drive surface and the cam surface, each of the side edges having an outer portion extending inward from the drive surface and an inner portion extending outward from the cam surface and joining the outer portion at an obtuse angle; and

a web of elastomeric material bonded to the inner and outer portions of each side edge and extending between adjacent ones of the jaws.

2. The apparatus according to claim 1, further comprising:

an outer groove located at an interface between the web and the outer portion of each of the side edges; and

an inner groove located at an interface between the web and the inner portion of each of the side edges.

3. The apparatus according to claim 1, further comprising:

an axially extending outer groove located at an interface between the web and the outer portion of each of the side edges; and

an axially extending inner groove located at an interface between the web and the inner portion of each of the side edges, the inner and outer grooves being parallel with each other.

4. The apparatus according to claim 1, further comprising:

an axially extending outer groove located in the outer portion of each of the side edges;

an axially extending inner groove located in the inner portion of each of the side edges; and

wherein each of the webs extends into and is bonded to both of the grooves on adjacent ones of the jaws.

5. The apparatus according to claim 1, wherein:

an inner portion line normal to the inner portion of each of the side edges extends inward of the inner portion of an adjacent one of the jaws; and

an outer portion line normal to the outer portion of each of the side edges extends outward of the outer portion of an adjacent one of the jaws.

6. The apparatus according to claim 1, wherein:

the outer portion of each of the side edges is located in an outer portion plane;

the inner portion of each of the side edges is located in an inner portion plane;

the outer portion planes of adjacent ones of the jaws diverge from each other in an outward direction; and

the inner portion planes of adjacent ones of the jaws converge toward each other in an outward direction.

7. The apparatus according to claim 1, wherein the cam surface of each of the jaws from one of the side edges to the other of the side edges is configured at a single radius from the axis.

8. The apparatus according to claim 1, wherein the camshaft and the base are formed of a single piece of metal.

9. The apparatus according to claim 1, wherein:

the camshaft comprises three curved lobes separated from each other by curved valleys; each of the lobes being formed at a single radius; and

each of the valleys being formed at a single radius that is smaller than the radius of each of the lobes.

10. An apparatus for rotating a work piece having a cavity, comprising:

a base having a first end with a polygonal opening for receiving a rotary tool to impart rotation to the base;

a camshaft extending from a second end of the base along a longitudinal axis of the base for rotation with the base, the camshaft and the base being integrally formed with each other from a single piece of material;

the camshaft having three rounded lobes separated from each other by three rounded valleys, each of the lobes being symmetrical about a lobe midpoint, and each of the valleys being symmetrical about a valley midpoint;

each of the lobe midpoints being a greater distance from the axis than each of the valley midpoints; and

three jaws spaced around the camshaft, each of the jaws having an outward facing drive surface configured to engage the cavity of the work piece and an inward facing cam surface in engagement by the camshaft, wherein an increment of rotation of the base and the camshaft relative to the jaws causes the jaws to move radially outward into engagement with the cavity of the work piece.

11. The apparatus according to claim 10, wherein a distance from each of the valley midpoints to the axis in the range from 60 to 80 percent distance from each of the lobe midpoints to the axis.

12. The apparatus according to claim 10, wherein:

each of the lobes has a single lobe radius from a lobe center point to any place along each of the lobes between a junction with one of the valleys to a junction with an adjacent one of the valleys; and

each of the valleys has a single valley radius from a valley center point to any place along each of the valleys between a junction with one of the lobes to a junction with an adjacent one of the lobes.

13. The apparatus according to claim 10, wherein:

each of the jaws has opposite side edges extending from the drive surface to the cam surface;

each of the side edges has an outer portion extending inward from the drive surface and joining an inner portion extending inward from the outer portion to the cam surface; and

an outer portion line normal to a midpoint along the outer portion diverges from an inner portion line normal to a midpoint along the inner portion.

14. The apparatus according to claim 10, wherein:

each of the jaws has opposite side edges extending from the drive surface to the cam surface;

each of the side edges has an outer portion extending inward from the drive surface and joining an inner portion extending inward from the outer portion to the cam surface;

an outer portion line normal to a midpoint along the outer portion diverges from an inner portion line normal to a midpoint along the inner portion; and

an elastomeric web extends between adjacent ones of the jaws and is bonded to the inner and outer portions of the side edges.

15. An apparatus for rotating a work piece having a cavity with internal drive flats, comprising:

a base having a first end with a polygonal opening for receiving a rotary tool to impart rotation to the base;

a camshaft extending from a second end of the base along a longitudinal axis of the base for rotation with the base;

a sleeve carried on the second end of the base with the camshaft extending through the sleeve, the sleeve having an annular internal groove that axially aligns with an annular external groove on the second end of the base;

a spring located in the internal and external grooves, the spring retaining the sleeve on the base and allowing the base and the camshaft to rotate an increment relative to the sleeve;

a shell of elastomeric material having a cylindrical portion extending into and bonded to a bore of the sleeve, the shell having an external portion exterior of the sleeve with a plurality of slots formed therein and spaced around the axis;

a plurality of metal jaws, each of the jaws being located in one of the slots, each of the jaws having an outward facing drive surface with external drive flats configured to engage the internal drive flats of the work piece, each of the jaws having an inward facing cam surface in engagement by the camshaft, wherein an increment of rotation of the base and the camshaft relative to the sleeve causes the jaws to move radially outward into engagement with the internal drive flats of the work piece;

each of the jaws having two side edges extending between the drive surface and the cam surface, each of the side edges having an outer portion extending inward from the drive surface and an inner portion extending outward from the cam surface and joining the outer portion at an obtuse angle greater than 180 degrees; and

wherein the elastomeric material of the shell at each of the slots is bonded to the inner and outer portions of the side edges and of adjacent ones of the jaws.

16. The apparatus according to claim 15, further comprising:

an axially extending outer groove located in the outer portion of each of the side edges;

an axially extending inner groove located in the inner portion of each of the side edges; and

wherein each of the webs extends into and is bonded to both of the grooves on adjacent ones of the jaws.

17. The apparatus according to claim 15, wherein:

an inner portion line normal to the inner portion of each of the side edges extends inward of the inner portion of the side edge of an adjacent one of the jaws; and

an outer portion line normal to the outer portion of each of the side edges extends outward of the outer portion of an adjacent one of the jaws.

18. The apparatus according to claim 15, the cam surface of each of the jaws from one of the side edges to the other of the side edges is configured at a single radius from the axis.

19. The apparatus according to claim 15, wherein:

the camshaft comprises three curved lobes separated from each other by curved valleys;

each of the lobes being formed at a radius; and

each of the valleys is formed at a radius that is smaller than the radius of each of the lobes.

20. The apparatus according to claim 19, wherein:

each of the lobes has a single lobe radius from a lobe center point at any place along each of the lobes from a junction with one of the valleys to a junction with an adjacent one of the valleys; and

each of the valleys has a single valley radius from a valley center point at any place along each of the valleys from a junction with one of the lobes to a junction with an adjacent one of the lobes.