High energy impact-based material removal apparatus

Abstract

A material removal apparatus for removing a material from a surface is provided. The material removal apparatus comprises a frame having distal and proximal frame portions, the proximal frame portion comprising a handle. A tool shaft is slidably mounted to the frame, the tool shaft having proximal and distal shaft ends and a longitudinal shaft axis. The tool shaft is movable between a first shaft position and a second shaft position distal to the first position. A tool head attached to the distal shaft end is adapted for engaging the material to be removed. The material removal apparatus also comprises an impulse delivery arrangement attached to the frame. The impulse delivery arrangement is adapted for selectively applying a discrete impulsive force to the proximal shaft end.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation-in-Part of U.S. application Ser. No. 10/972,283 filed Oct. 25, 2004, which is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

The invention relates to the field of construction equipment, and in particular relates to powered tools for removing materials such as shingles or fasteners from surfaces, and for demolition.

Shingles are frequently used to protect inclined roofs. The shingles may be asphalt, or wood, or tiles, and may be attached to the roof by nails or staples. Asphalt shingles faced with granular stone are often nailed into overlapping rows, with the upper row overlapping the lower row in order to keep out water. A layer of tar paper may be underneath the shingles. The shingles and tar paper are often attached to a wood roof. The wood roof often comprises inclined plywood nailed onto rafters.

Shingles degrade with time and weather, and must be replaced regularly. Old shingles and tar paper may be removed using many types of manual tools such as: crowbar, hammer, shovel, and pitchfork. Many nails are left behind after the shingles are removed with these manual tools. Any remaining nails must be removed after the shingles are removed. Thus, removing shingles is very labor intensive, very expensive, and very slow.

Numerous attempts have been made to improve the removal of shingles, felt, and nails from roof surfaces. For example, U.S. Pat. No. 4,663,995 discloses a machine with a powered lifting plate to lift the nails out. This machine requires the human operator to physically push the machine into position before activating the powered lifting plate. U.S. Pat. No. 4,709,479 discloses a powered lifting plate to lift the felt and nails out, and also powered wheels to simultaneously push the machine forward. U.S. Pat. Nos. 4,763,547 and 4,858,503 and 5,001,946 disclose various powered lifting plates.

Another approach to the problem is to use a reciprocating tool to strip materials from the roof surface. U.S. Pat. Nos. 5,076,119; 5,71,047; 5,741,047; and 6,393,948 each disclose a reciprocating blade. U.S. Pat. No. 5,800,021 also discloses a reciprocating blade, this time with the blade comprising wedge-shaped teeth. U.S. Pat. No. 5,906,145 discloses the use of a vibrating shovel blade.

None of the above solutions have proven to be completely satisfactory. Most of the tools that have been used until now have been bulky and difficult to manipulate. Many of them are usable only to remove the shingles themselves without regard to the nails holding them to the surface. In general, vibratory or reciprocating tools are relatively ineffective for removing shingles and fasteners from roofing surfaces.

SUMMARY OF THE INVENTION

An illustrative embodiment of the invention provides a material removal apparatus for removing a material from a surface. The material removal apparatus comprises a frame having distal and proximal frame portions, the proximal frame portion comprising a handle. A tool shaft is slidably mounted to the frame, the tool shaft having proximal and distal shaft ends and a longitudinal shaft axis. The tool shaft is movable between a first shaft position and a second shaft position distal to the first position. A tool head attached to the distal shaft end is adapted for engaging the material to be removed. The material removal apparatus also comprises an impulse delivery arrangement attached to the frame. The impulse delivery arrangement is adapted for selectively applying a discrete impulsive force to the proximal shaft end.

Another illustrative embodiment of the invention provides another material removal apparatus for removing a material from a surface. The material removal apparatus comprises a frame having distal and proximal frame portions, the proximal frame portion comprising a handle. The material removal apparatus also comprises an impulse delivery arrangement attached to the frame. The impulse delivery arrangement comprises an air cylinder having proximal and distal cylinder ends intersected by a longitudinal cylinder axis and being connectable to a pressurized air source. A piston is slidably disposed within the air cylinder so as to be movable along the longitudinal cylinder centerline between a first piston position to a second piston position distal to the first position. The piston and the air cylinder are configured so that movement of the piston may be controlled through selective introduction of compressed air from the pressurized air source into the air cylinder. The material removal apparatus further comprises a tool shaft slidably mounted to the frame. The tool shaft has proximal and distal shaft ends and a longitudinal shaft axis that is substantially collinear with the longitudinal cylinder axis. The tool shaft is movable between a first shaft position and a second shaft position distal to the first position. The first shaft position is established so that the piston can make contact with the proximal end of the tool shaft when the tool shaft is in the first position and the piston is in a contact position intermediate the first and second piston positions. A tool head attached to the distal end of the tool shaft is adapted for engaging the material to be removed.

Further objects, features and advantages of the invention will be apparent from the detailed description below taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graphic comparison of the force applied by material removal devices according to the invention with the force applied by a conventional air hammer;

FIG. 2 is a side view of a material removal apparatus according to an embodiment of the invention;

FIG. 3 is a top view of the apparatus of FIG. 2;

FIG. 4 is a section view of a portion of a material removal apparatus according to an embodiment of the invention;

FIG. 5 is a perspective view of a tool head that may be used in conjunction with material removal apparatus according to an embodiment of the invention;

FIG. 6A is a perspective view of a tool head that may be used in conjunction with material removal apparatus according to an embodiment of the invention;

FIG. 6B is a section view of the tool head of FIG. 6A;

FIG. 7 is a perspective view of a tool head that may be used in conjunction with material removal apparatus according to an embodiment of the invention;

FIG. 8A is a side view of a tool head that may be used in conjunction with material removal apparatus according to an embodiment of the invention;

FIG. 8B is a top view of the tool head of FIG. 8A;

FIG. 9 is a top view of a material removal apparatus according to an embodiment of the invention; and

FIG. 10 is a section view of a portion of a material removal apparatus according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a relatively lightweight, powered material removal apparatus that can be used to remove materials such as shingles and nails from inclined roofs, and for other removal and demolition tasks. The material removal apparatus uses an impactor to deliver discrete high impact pulses to a tool for removing materials from a surface. The use of a compressed air driven piston as the impactor allows the delivery of high kinetic energy and momentum to a tool shaft and tool head through an impulsive impact. The kinetic energy and momentum from the tool shaft is then transmitted to the material to be removed in a single high energy stroke rather than multiple lower energy pulses delivered through a generally vibrating or reciprocating motion. The discrete high energy stroke of the removal tool of the invention serves to force the tool head beneath the materials to be removed. The tool head may be configured so that it may be subsequently operated as a lever to lift the material from the surface.

As discussed above, existing tools often use reciprocating action for material removal. FIG. 1 illustrates the conceptual difference between the material removal apparatus of the invention and a reciprocating tool such as an air hammer. The material removal apparatus of the invention applies a single, discrete high energy impulsive force that may be two orders of magnitude higher than the repetitive force applied by an air hammer of similar size. This single, high energy pulse has been found to be more effective for many material removal applications and, in pneumatic embodiments, uses significantly less air than an air hammer.

The main components of a material removal apparatus according to the invention will now be described. The tool head is attached to the distal end of a tool shaft slidably mounted to a housing or frame. The tool head and tool shaft may be separate parts joined or removably attached to one another or may be formed as a single integral part. The proximal end of the tool shaft (i.e., the end nearer the user of the material removal apparatus) is adapted for receiving an impulse load from a piston or other actuator body. The frame or housing supports an impulse delivery arrangement that is adapted for delivering a discrete impulse load to the proximal end of the tool shaft upon demand. This load is transmitted to the tool head, which is propelled distally along its axis until it reaches a maximum stroke length or until it encounters an obstruction. The energy imparted to the tool head is transmitted to any materials or objects encountered by the tool head during its stroke.

The material removal apparatus may have a stiff, light-weight frame to which various components may be mounted. The frame may also form an integral portion of various components, such as the exterior wall of an air cylinder, or the exterior wall of an air accumulator. In some embodiments, the frame may be replaced or supplemented by a housing that serves to protect the working components from the environment, and to protect the user from injury caused by moving parts. The housing may also serve as a portion of the working components. For example, the housing may serve as the exterior wall of an air cylinder.

After the tool head is impulsively driven under or into the material to be removed, the frame and the tool head may be used together much like a conventional handle or pry bar for lifting up the material. The frame may have a handle of any suitable shape, e.g. a D-shaped or T-shaped handle, and may have an additional side mounted tubular handle for guiding and controlling the material removal apparatus manually.

In some embodiments of the invention, the impulse delivery arrangement includes a compressed air-driven actuator comprising a piston slidably disposed in an air cylinder. Compressed air may be selectively introduced into the air cylinder through the use of a multi-port valve. The air cylinder and piston are arranged and mounted so that the piston travels along a path axially aligned with the axis of the tool shaft. The piston and cylinder are constructed so that a distal portion of the piston makes contact with the proximal end of the tool shaft when the piston is at or near the distal end of its stroke. The compressed air-driven actuator may be a single-acting or double-acting actuator.

Mounting points may be provided on the frame for mounting the air cylinder and valve, a trigger for selectively activating the valve, and associated tubing. Guides incorporated into the frame may be used to axially align the tool shaft with respect to the air cylinder. The handle may have a trigger mechanism that operates the multi-port valve used to control the airflow to the air cylinder. The frame may have stops for limiting the travel of the tool shaft.

Compressed air imparts great kinetic energy and momentum to the piston. Near the end of its stroke, the piston provides a hammering impulsive strike to a tool assembly. The hammering impulsive strike of the piston against the tool assembly transfers much or all of this kinetic energy and momentum to the tool assembly. The tool assembly then transmits the hammering impulsive strike to or under the material to be removed, similarly transferring much or all of the kinetic energy and momentum to that material.

As noted above, the tool assembly may comprise a tool shaft and a tool head. The tool shaft may be slidably mounted to the frame or housing using guides that provide axial alignment with the piston shaft, and that allow movement in the axial direction. The tool shaft may have a non-circular (e.g., elliptical or square or other polygonal shape) cross section with the guides shaped in complementary fashion so as to restrict rotational movement. This assures that the rotational angle of the tool head may be fixed relative the frame. The tool shaft may extend from the lower guide of the frame.

In some embodiments, the tool head may be removably attached to the tool shaft by means of pinning or other fastening method. This allows for easy replacement of the tool head. Alternatively, the tool head may be permanently attached to the tool shaft or integrally formed therewith. The tool head may be configured in any of a variety of forms tailored to particular uses. These may include, without limitation, the end of a conventional roofing shovel, a nail removal shovel blade with integral fulcrum, flat bars, scrapers, wedges, punches, cutting blades, and specialty application tools such as guided prying wedges or cutting tools (e.g. a wedge with a channel shaped guide attached to the bottom of the wedge to guide it along the top of a rafter when removing sheathing).

In a particular embodiment, the tool head includes a mounting tube adapted for receiving the distal end of the tool shaft. The mounting tube may be fixed to the tool shaft using any suitable bonding material or fastening mechanism. The distal-most shaft guide may be configured with a larger diameter than the more proximal guide(s) in order to accommodate the mounting tube. The inserting of the tool shaft into the tool mounting tube effectively increases the moment of inertia of the combined members to resist bending.

In alternative embodiments, the impulse delivery arrangement of the material removal apparatus may use an impactor driven by sources of energy other than compressed air. These may include, for example, pressurized liquids (hydraulics), chemical reactions, or electricity, or other sources of energy. Chemical reactions may include, without limitation: solid explosive charges similar to those used in some nail guns, liquid explosive charges (e.g., a fuel/air mixture). Electrical may include using a battery to provide electricity. A a small gasoline burning piston engine may be used provide mechanical power.

Many sources of energy may provide energy at relatively low levels of power, and in these circumstances the impulse delivery arrangement may accumulate the energy before delivering the energy in an impulse. For example, a small light electric motor may slowly compress a powerful spring.

In some embodiments, the material removal apparatus may include a pressurizable air accumulator, which may be discharged upon triggering the valve. This may reduce the pressure drop in the compressed air line when the piston is triggered. The air accumulator may be a separate vessel attached to the frame or may be incorporated into the handle. The handle may also serve as a manifold, routing air to and from the piston. In underwater use, the exhausted air may be routed to the surface. Also in underwater use, both sides of a double action piston may be at least slightly pressurized in order to prevent water intrusion (i.e., operate under positive pressure with respect to the external water pressure).

A single acting piston reduces the number of exposed hoses, does not need a pressure regulator, and is very reliable. The single action piston, however, requires a restoring force to return it to its initial position after delivering an impulse to the tool shaft. The restoring force may be in the form of a spring, which serves to bias the piston in its ready position adjacent the proximal end of the air cylinder. A double acting piston requires no return spring pressure to overcome and may be shorter and lighter in weight. The exhaust return pressure can be controlled by a pressure regulator which may reduce the impact of piston return, and can be used underwater.

It will be understood that the bulk of the material removal apparatus weight may be found near the upper end of the material removal apparatus to provide the operator with better control and ease of handling the apparatus.

Operation of exemplary embodiments of the present invention will now be described. Any specific dimensions, angular orientations or configurations depicted in the figures are for representation of the exemplary embodiments herein and should not be interpreted as limiting or restrictive to the scope of the invention.

With reference to FIGS. 2-4, a material removal apparatus 100 according to an exemplary embodiment of the invention comprises a frame 3, an impulse delivery arrangement 43, and a tool assembly 44. The frame 3 is structured to support the impulse delivery arrangement 43 and the tool assembly 44. The frame 3 may be formed from any type of lightweight structural members. In a preferred embodiment, the frame is formed from one or more tubular members to which the other components of the material removal apparatus may be attached. In the illustrated embodiment, the frame 3 is formed as a single elongate tubular member having a distal portion to which the tool assembly 44 is attached, an intermediate portion to which the impulse delivery arrangement 43 is attached and a proximal portion 40 that forms a handle for the user. The intermediate portion of the frame 3 may have a curve 19 that serves to align the impulse delivery arrangement 43 with the tool assembly 44.

The tool assembly 44 comprises a tool head 15 removably attached to the distal end of a tool shaft 9. The tool shaft 9 is an elongate member that is strong enough to receive an impulse load and transmit it to the tool head 15 without bending and with minimal energy loss. The tool shaft 9 may have a substantially square cross-section. The tool head 15 includes a mounting tube 12 adapted for receiving the distal end of the tool shaft 9. The mounting tube 12 is held in place on the end of the tool shaft 9 by pins 11 or other removable fasteners. As will be discussed in more detail below, the tool head 15 may be configured in a variety of shapes to facilitate material removal.

The tool assembly 44 is held to the frame 3 by a plurality of guides through which the tool shaft 9, the mounting tube 12 or both the tool shaft 9 and the mounting tube 12 are slidably disposed. In the illustrated embodiment, an upper portion of the tool shaft 9 is disposed through a proximal guide 10 and the mounting tube 12 is disposed through a distal shaft guide 16. The shaft guides 10, 16 are configured to conform to and slidably accommodate the tool shaft 9 and mounting tube 12 with minimal friction and minimal play.

The impulse delivery arrangement 43 of the material removal apparatus 100 includes an air cylinder 6 a multi-port valve 4, and a trigger mechanism 2. The air cylinder 6 is an annular tube sealed at its proximal end by a top cap 17 and at its distal end by a bottom cap 18. The top cap 17 has a threaded port 20 adapted for receiving fittings attached to the air supply tubing 5. O-rings 21 serve to seal the cap 17. The air cylinder 6 may also include a bottom cap 18 that may contain holes 24 to let air in or out and a shaft guide 25 to seal around and guide a piston shaft 8. Additional O-rings 21 serve to seal the bottom cap 18.

A piston 52 may have a piston head 23 with a piston shaft 8 extending distally therefrom. The piston head 23 is adapted for slidable disposition within the interior of the air cylinder 6 and for sealing the portion of the air cylinder interior proximal to the piston head 52. Piston rings 22 may be used to maintain the seal. The piston head 23 is attached to the proximal end of the piston shaft 8 which is slidably disposed through the shaft guide 25 so that the piston shaft 8 extends distally from the distal end of the air cylinder 6.

The air cylinder 6 and piston 52 are configured and positioned so that the piston shaft 8 is axially aligned with the tool shaft 9. When the piston head 23 is in the initial or ready position shown in FIG. 2, there is a gap between the distal end of the piston shaft 8 and the proximal end of the tool shaft 9. When compressed air is introduced through the port 20, the piston 52 is forced to move rapidly in the distal direction relative to the air cylinder 6. This causes the distal end of the piston shaft 8 to make contact with the proximal end of the tool shaft 9 and transmit an impulse load thereto.

The air cylinder 6 is attached to the frame 3 using a plurality of brackets or other suitable mounting hardware. A proximal mount 13 may be used to mount the top cap 17 to the frame 3 and a distal mount 14 may be used to mount the bottom cap 18.

The multi-port valve 4 of the impulse delivery arrangement 43 may be any suitable valve assembly that provides rapid cycling for delivery of air from a compressed air source to the air cylinder 6 through tubing 5. The multi-port valve 4 may be electrically controlled by a trigger 2 mounted to the handle 40 or elsewhere on the frame 3. Air may be delivered to the valve 4 using any suitable tubing. Alternatively, the handle portion 40 of the frame 3 may be configured as an air reservoir having an air inlet 1 and an outlet to which the valve 4 is in fluid communication.

As discussed above, the frame 3 may be configured for use as a lever to pry up material. To facilitate this action, the material removal apparatus 100 may include a fulcrum or engagement fixture 26 attached to the distal end of the frame. The engagement fixture 26 may be removably attached to the frame 3 with a fulcrum pin 27 or other removable fastener. Alternatively, the engagement fixture may be permanently attached to the frame 3 or may be integrally formed therewith.

The handle portion 40 of the frame 3 may be formed in a “D” or “T” shape. The handle portion 40 may be attached to the other portions of the frame 3 or may be integrally formed therewith.

As discussed above, the tool head may be formed in any of a variety of configurations. FIGS. 5-8 are exemplary embodiments of various configurations for the tool head 15. FIG. 5 illustrates a crowbar-shaped tool head 15a that is useful for removing single large nails, and for removing boards. FIGS. 6A and 6B illustrate a chisel-shaped tool head 15b that is useful for breaking fasteners such as small bolts. In this configuration, a channel 90 is formed at the bottom of the tool head 15b for guiding the tool along a rafter while removing sheathing, or guiding along a stud while removing drywall. FIG. 7 illustrates a scraper-shaped tool head 15c that is useful for removing adhesively attached tiles and tar paper and for scraping ship hull surfaces. FIG. 8 illustrates a pointed shovel shaped tool head 15d. This tool head 15d has a flat horizontal component 92 to penetrate under shingles and a vertical component 94 to act as a wedge to raise the shingles.

In an alternative embodiment of the invention, a material removal apparatus uses an impulse delivery arrangement with a compressed air driven impactor that is particularly well suited to underwater use. With reference to FIGS. 9 and 10, a material removal apparatus 200 according to this embodiment includes a frame 203, an impulse delivery arrangement 243, a tool assembly 244 and a housing 233. As shown in FIG. 9, the frame 203 comprises an air accumulator 232 that may be integrated into the handle portion 202 of the frame 203. For example, the air accumulator 232 may be a hollow portion of the frame 203 that defines a chamber 234 that is sealed to provide a pressurized reservoir for compressed air introduced through the air inlet 201.

The chamber 234 of the air accumulator 232 is connected by tubing 205 to a multi-port valve 204 and by separate tubing 207 to a pilot valve 231. The multi-port valve 204 is connected to an air cylinder 206 by an inlet tube 251 and an outlet tube 253. The multi-port valve 204 is also connected to an exhaust tube 261, the opposite end of which is open to the atmosphere.

The air cylinder 206 is an annular cylinder that is open at its distal end and closed by a cylinder cap 255 at its proximal end. The inlet tube 251 is connected by a fitting to the cylinder cap 255 so that air can be passed into the air cylinder through a cylinder inlet port 257. The outlet tube 253 is connected to the air cylinder 206 near its distal end so that air can be passed out of the air cylinder 206 through the cylinder outlet port 259. A proximal portion of a cylindrical shaft housing 233 is fixedly disposed within the distal end of the air cylinder 206. The cylindrical housing is also attached to the frame 203.

A piston 223 is slidably disposed within the interior of the air cylinder 206 so that when compressed air is introduced through the inlet port 257 and/or removed through the outlet port 259 so as to produce a pressure differential across the piston 223, the piston 223 is forced to move in the distal direction. Conversely, if air is introduced into the cylinder through the outlet port 259 and/or withdrawn from the inlet port 257, the piston 223 is forced to move in the proximal direction. The piston 223 may be provided with seals 242 to prevent the flow of air around the piston 223.

The multi-port valve 204 is configured to control the flow of air into and out of the air cylinder 206 through the inlet and outlet ports 257, 259. The multi-port valve 204 may be adapted to control the air flow so that, for an impulse stroke, a large pressure differential is established across the piston 223 so as to produce a large acceleration of the piston 223 in the distal direction. The multi-port valve 204 may also be adapted to control the air flow so that, for a return stroke, a smaller pressure differential is established across the piston 223 so as to produce a smaller acceleration of the piston 223 in the proximal direction. A pressure regulator (not shown) may be used to limit the pressure differential on the proximal return stroke.

The outlet tube 253 may be a separate tube as shown in FIG. 9 or, alternatively, may be integrally formed with or bored into the wall of the air cylinder 206. The air cylinder 206 may also serve as a load bearing portion of the frame 203. In other embodiments, the air cylinder 206 and outlet tube 253 may be disposed within an outer housing that may be attached to or included as a load-bearing part of the frame 203.

The tool assembly 244 includes a tool shaft 209 and a tool head 215. The tool head 215 may be substantially similar to those of earlier described embodiments. The tool shaft 209 is configured and positioned so that its proximal end 260 is disposed within the interior of the air cylinder 206 with its longitudinal axis aligned with the air cylinder centerline 258. The tool shaft 209 may have a broadened contact head 262 at its proximal end 260 to increase the contact area between the piston 223 and the tool shaft 209 during an impulse stroke. The tool shaft 209 may have a single cross-sectional shape that may be circular, elliptical, square or other geometric shape. In some embodiments, the tool shaft 209 may have a plurality of shapes. In the embodiment illustrated in FIG. 10, the tool shaft 209 has a proximal portion 290 with a circular cross-section and a distal portion 292 with a non-circular cross-section.

The tool shaft 209 is slidably supported and aligned by a plurality of bushings sized and shaped to conform to the cross-section of the tool shaft 209. An air cylinder bushing 270 is disposed within the interior of the air cylinder 206 distal to the outlet port 259. The air cylinder bushing 270 is held in place by a bushing retainer 271, which, in combination with a seal 272, serves to seal the distal end of the air cylinder 206. The use of a circular shaft cross-section and a circular air cylinder bushing 270 allows the tool shaft 209 to be selectively rotated relative to the air cylinder 206.

One or more additional bushings may be disposed within the shaft housing 233. In a particular embodiment, there is a proximal shaft housing bushing 273 and a distal shaft housing bushing 276 fixedly attached to the interior wall of the housing 233. The proximal shaft housing bushing 273 is held in place by a bushing retainer 274. An optional seal 275 may be provided, which together with the bushing retainer 274 seals the proximal end of the shaft housing 233. The distal shaft housing bushing 276 is held in place by a bushing retainer 277 and is configured to conform to the non-circular shaft portion 292. As a result, the tool shaft 209 cannot be rotated relative to the shaft housing 233. The shaft housing 233, however, may be mounted so that it can be rotated relative to the air cylinder 206. By virtue of the non-circular portion 292 of the tool shaft 209, rotation of the shaft housing 233 relative to the air cylinder 206 will also rotate the tool shaft 209 relative to the air cylinder 206. This allows for easy adjustment of the rotational angle of the tool head 215 while maintaining an air-tight and water-tight seal of the air cylinder 206.

The material removal apparatus 200 may be activated through the use of a control lever 229, which activates the pilot valve 231. The pilot valve 231 introduces air into the multi-port valve 204 for actuation thereof. Upon activation, the multi-port valve 204 establishes a pressure differential around the piston 223 causing it to accelerate and strike the contact head 262 of the tool shaft 209 with an impulse load. The tool shaft 209 transmits this load to the tool head 215 which imparts the impulse to the material to be removed. Upon release of the control lever 229, the multi-port valve 204 establishes a return differential pressure around the piston 223 to cause the piston 223 to return to the proximal end of the air cylinder 206.

The tool shaft 209 may be returned to its proximal position by the action of the user in moving the entire material removal apparatus 200 in the distal direction. If and when the tool head 215 encounters resistance to the distal movement (e.g., friction or an obstruction), continued movement of the tool frame 203 in the distal direction causes the tool head 215 and tool shaft 209 to move proximally relative to the tool frame 203 and the impulse delivery arrangement 243 until the tool shaft is in its proximal position or until an additional impulse is applied.

In some embodiments, an automatic trigger arrangement may be used to trigger additional impulse applications whenever the tool shaft is returned to its proximal position as a result of encountering resistance to distal movement of the tool head 215. The trigger arrangement may include any switch mechanism (e.g., a micro-switch) that closes to trigger the pilot valve 231 when the tool shaft 209 is in a predetermined position relative to the frame 203 and/or the impulse delivery arrangement 243. When the impulse is applied, the shaft 209 is moved distally away from this predetermined position and the switch opens. In some such embodiments, a biasing mechanism such as a spring may be used to bias the tool shaft 209 away from the predetermined proximal position so that the automatic trigger mechanism will only be triggered upon the tool head 215 encountering a predetermined level of resistance.

In alternative embodiments to the above, a biasing mechanism may be used to bias the tool shaft 209 in the proximal direction. This may serve to return the tool shaft more quickly to its proximal position for repeated impulse application.

Because of its sealed impulse delivery arrangement, the material removal apparatus 200 is particularly adapted for use in an underwater environment. In addition, its double action air cylinder provides for rapid reset of the device for application of sequential discrete pulses to the material to be removed.

EXAMPLES

It will be understood that the material removal apparatus of the present invention may be constructed and scaled to any size for a particular application. In a typical hand-held, one-man material removal apparatus according to the invention, the combined weight of the tool shaft and tool head is in a range of about 1 pound and to about 5 pounds. A typical impactor weight is also in a range of about 1 pound and to about 5 pounds. In embodiments in which the impactor is a compressed air-driven piston, the operating air pressure may be in a range of about 30 psi to about 175 psi. The piston diameter is typically from about 1 to about 3 inches and the piston stroke is typically in a range from about 3 inches to about 9 inches.

An exemplary embodiment of a compressed air-driven material removal apparatus according to the invention may be used to illustrate the energy imparted to the tool head. The exemplary material removal apparatus has a piston with a diameter of 3.0 inches and a piston stroke of 2.0 inches. The weight of the piston is 2 pounds, and the combined weight of the tool shaft and tool head is 2 pounds. The area of the top of the piston is equal to 3.14 times the square of the piston radius, which equals 7.06 square inches. The force acting on the piston equals the cross-sectional area of the piston times the differential pressure across the piston. For a differential pressure of 100 psi, the force on the piston is 706 lbf. As the piston is accelerated distally, it will have a kinetic energy level equal to the work done in displacing it from its initial position; i.e., K.E.=Work=Force*Distance. Assuming an ideal one dimensional elastic collision between the piston and the tool shaft, the maximum energy that could be imparted to the tool shaft (“maximum impact energy”) can be calculated. The maximum impact energy will be achieved if the collision occurs at the end of the full stroke length of the piston. For a force of 706 lbf and a stroke of 2.0 inches, the maximum impact energy is 118 ft-lbf.

A range of the maximum impact energy for a hand-held removal tool can be established using the parameter ranges noted above. At one end of the range, a material removal apparatus has a piston diameter of 1.0 inch, a piston stroke of 3 inches, a piston weight of 1 pound and a tool shaft/head weight of 1 pound. For an air pressure differential of 30 psi, the maximum impact energy is 5.9 ft-lbf. At the other end of the range, a material removal apparatus has a piston diameter of 3.0 inches, a piston stroke of 9 inches, a piston weight of 5 pounds and a tool shaft/head weight of 5 pounds. For an air pressure differential of 175 psi, the maximum impact energy is 927 ft-lbf.

It can therefore be seen that a one man material removal apparatus of the compressed air/piston type can achieve a maximum impact energy in a range of about 5 ft-lbf to about 1000 ft-lbf.

It will be readily understood by those persons skilled in the art that the present invention is susceptible to broad utility and application. Many embodiments and adaptations of the present invention other than those herein described, as well as many variations, modifications and equivalent arrangements, will be apparent from or reasonably suggested by the present invention and foregoing description thereof, without departing from the substance or scope of the invention.

While the foregoing illustrates and describes exemplary embodiments of this invention, it is to be understood that the invention is not limited to the construction disclosed herein. The invention can be embodied in other specific forms without departing from the spirit or essential attributes.

Claims

1. A material removal apparatus for removing a material from a surface, the material removal apparatus comprising:

a frame having distal and proximal frame portions, the proximal frame portion comprising a handle;

a tool shaft slidably mounted to the frame, the tool shaft having proximal and distal shaft ends and a longitudinal shaft axis, the tool shaft being movable between a first shaft position and a second shaft position distal to the first position;

a tool head attached to the distal shaft end, the tool head being adapted for engaging the material to be removed; and

an impulse delivery arrangement attached to the frame, the impulse delivery arrangement being adapted for selectively applying a discrete impulsive force to the proximal shaft end.

2. A material removal apparatus according to claim 1 wherein the impulse delivery arrangement comprises an impactor adapted for selectively contacting the proximal shaft end to apply the discrete impulsive force thereto and means for accelerating the impactor to a desired impact velocity with which the impactor contacts the proximal shaft head.

3. A material removal apparatus according to claim 2 wherein the impactor has a kinetic energy in a range of about 5 ft-lbf to about 1000 ft-lbf at the impact velocity.

4. A material removal apparatus according to claim 1 wherein the apparatus is sized for carriage and use by a single human user.

5. A material removal apparatus according to claim 1 further comprising means for biasing the tool shaft toward the first shaft position.

6. A material removal apparatus according to claim 1 wherein the impulse delivery arrangement comprises:

an air cylinder having a closed proximal cylinder end and a distal cylinder end intersected by a longitudinal cylinder axis, the air cylinder being connectable to a pressurized air source for fluid communication therewith;

a piston slidably disposed within the air cylinder so as to be movable along the longitudinal cylinder centerline between a first piston position and a second piston position distal to the first position,

wherein the piston and the air cylinder are configured so that movement of the piston may be controlled through selective introduction of compressed air into the air cylinder and wherein the longitudinal shaft axis is substantially collinear with the longitudinal cylinder axis and the first shaft position is established so that the piston can make contact with the proximal end of the tool shaft when the tool shaft is in the first position and the piston is in a position intermediate the first and second piston positions.

7. A material removal apparatus according to claim 6 wherein the air cylinder has an inner cylindrical wall and the distal cylinder end is open and wherein the tool shaft is mounted to the frame by an annular cylindrical housing having proximal and distal housing ends, the proximal end being disposed within the air cylinder and being attached to the inner cylindrical wall so as to extend distally from the distal cylinder end.

8. A material removal apparatus according to claim 7 wherein a first portion of the tool shaft is slidably disposed through a first bushing mounted to the inner cylindrical wall proximal to the cylindrical housing and wherein a second portion of the tool shaft is slidably disposed through a second bushing mounted within the cylindrical housing

9. A material removal apparatus according to claim 7 wherein the first portion of the tool shaft has a circular cross-section and the second portion of the tool shaft has a non-circular cross-section.

10. A material removal apparatus according to claim 7 further comprising a seal mounted to the first bushing, the seal being adapted to inhibit fluid leakage into or out of a portion of the air cylinder proximal to the first bushing.

11. A material removal apparatus according to claim 3 further comprising a control valve adapted for selectively controlling a flow of compressed air from the compressed air source to the air cylinder.

12. A material removal apparatus according to claim 3 further comprising an air reservoir in selective fluid communication with the air cylinder and being connectable to the compressed air source.

13. A material removal apparatus according to claim 12 wherein the air reservoir is integrally formed with the frame.

14. A material removal apparatus for removing a material from a surface, the material removal apparatus comprising:

a frame having distal and proximal frame portions, the proximal frame portion comprising a handle;

a tool shaft slidably mounted to the frame, the tool shaft having proximal and distal shaft ends and a longitudinal shaft axis, the tool shaft being movable between a first shaft position and a second shaft position distal to the first position;

a tool head attached to the distal shaft end, the tool head being adapted for engaging the material to be removed;

impact means for selectively transferring an impact energy to the proximal shaft head; and

means for accelerating the impact means to a desired impact velocity.

15. A material removal apparatus according to claim 14 wherein the impact means comprises a piston.

16. A material removal apparatus according to claim 15 wherein the means for accelerating comprises an air cylinder selectively connectable to a compressed air source, the piston being slidably disposed in the air cylinder for acceleration by said compressed air.

17. A material removal apparatus according to claim 14 wherein the impact energy is in a range of about 5 ft-lbf to about 1000 ft-lbf.

18. A material removal apparatus according to claim 14 wherein the apparatus is sized for carriage and use by a single human user.

19. A material removal apparatus for removing a material from a surface, the material removal apparatus comprising:

a frame having distal and proximal frame portions, the proximal frame portion comprising a handle;

an impulse delivery arrangement attached to the frame, the impulse delivery arrangement comprising an air cylinder having proximal and distal cylinder ends intersected by a longitudinal cylinder axis and being connectable to a pressurized air source, and a piston slidably disposed within the air cylinder so as to be movable along the longitudinal cylinder centerline between a first piston position to a second piston position distal to the first position, the piston and the air cylinder being configured so that movement of the piston may be controlled through selective introduction of compressed air into the air cylinder;

a tool shaft slidably mounted to the frame, the tool shaft having proximal and distal shaft ends and a longitudinal shaft axis that is substantially collinear with the longitudinal cylinder axis, the tool shaft being movable between a first shaft position and a second shaft position distal to the first position, wherein the first shaft position is established so that the piston can make contact with the proximal end of the tool shaft when the tool shaft is in the first position and the piston is in a contact position intermediate the first and second piston positions; and

a tool head attached to the distal end of the tool shaft, the tool head being adapted for engaging the material to be removed.

20. A material removal apparatus according to claim 19 wherein the air cylinder has an inner cylindrical wall and the distal cylinder end is open and wherein the tool shaft is mounted to the frame by a an annular cylindrical housing having proximal and distal housing ends, the proximal end being disposed within the air cylinder and being attached to the inner cylindrical wall so as to extend distally from the distal cylinder end.

21. A material removal apparatus according to claim 19 wherein the piston has a kinetic energy in a range of about 5 ft-lbf to about 1000 ft-lbf when the piston is in the contact position.