SANDING TOOL

Abstract

A surface treatment apparatus for abrading a workpiece surface includes a motion generating device configured to move an abrasive disc, a stabilizer, and a force control device. The stabilizer and the force control device work cooperatively to prevent a force of contact between the abrasive disc and the workpiece surface from exceeding a set level. In one embodiment, the force control device has a maximum force control level, and the set level is less than the maximum force control level. In one embodiment, the stabilizer has a fixed portion and a movable portion.

Description

TECHNICAL FIELD

The present disclosure relates to surface treatment tool.

BACKGROUND

Painting and coating processes for automobile panels and other surfaces typically employ multiple coats, including primer, basecoat, color coats, clearcoat, and sealer, for example. Even with environmental air filtering, dust, dirt, lint, fibers, and other particles commonly become embedded in the finish between coats, thereby causing blemishes and other imperfections. These imperfections are generally sanded down to be level with the surrounding surface.

A trained operator using a state of the art hand held sander must apply the correct amount of force for the right amount of time and use proper lubrication. If the sanding parameters are not carefully controlled, the result may be a spot that is undercorrected or oversanded. An undercorrected spot generally leaves a residual blemish that requires more work. A spot that is oversanded may no longer be level with the remaining surface, causing a low or flat spot that is still discernable after buffing. Sometimes, operator error results in having to resand and refinish the entire workpiece and not just the defect spot. Moreover, the use of too much pressure or time or an incorrect angle can lead to increased or uneven wear of the abrasive material, thereby increasing replacement costs and time.

Thus, there remains a need for a handheld tool that can be set-up to automatically exhibit the correct abrasive parameters for a desired application, thereby allowing a less trained operator to achieve the desired results.

SUMMARY

One embodiment of a surface treatment apparatus for abrading a workpiece surface includes a motion generating device configured to move an abrasive disc, a stabilizer, and a force control device. The stabilizer and the force control device work cooperatively to prevent a force of contact between the abrasive disc and the workpiece surface from exceeding a set level. In one embodiment, the force control device has a maximum force control level, and the set level is less than the maximum force control level. In one embodiment, the stabilizer has a fixed portion and a movable portion.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of one embodiment of a tool of the present disclosure.

FIG. 2 is a cross-sectional view of the tool of FIG. 1, taken along line 2-2.

FIG. 3a is an enlarged cross sectional view of one embodiment of an abrading head of the tool in a disengaged position.

FIG. 3b is an enlarged cross sectional view of the abrading head of the tool in an engaged position.

FIG. 4 is a perspective view of an embodiment of a tool of the present disclosure, including hoses for lubricant application and removal.

FIG. 5a is an enlarged cross sectional view of one embodiment of an abrading head of a tool in an “off” position, the abrading head including an on/off switch.

FIG. 5b is an enlarged cross sectional view of the abrading head of FIG. 5a in an “on” position.

FIG. 6a is a perspective view of an embodiment of a tool of the present disclosure, including a projected light defect locator.

FIG. 6b is an enlarged cross sectional view of the abrading head of FIG. 6a.

While the above-identified drawing figures set forth several exemplary embodiments of the disclosure, other embodiments are also contemplated. This disclosure presents illustrative embodiments of the present invention by way of representation and not limitation. Numerous other modifications and embodiments can be devised by those skilled in the art which fall within the scope and spirit of the principles of the present disclosure. The drawing figures are not drawn to scale.

Moreover, while embodiments, components, and examples are referred to by the designations “first,” “second,” “third,” etc., it is to be understood that these descriptions are bestowed for convenience of reference and do not imply an order of preference. The designations are presented merely to distinguish between different embodiments for purposes of clarity.

Moreover, directional terms such as down, up, left, right, above, below, etc. are used only for ease of discussion. It is understood that the features discussed may be oriented in any manner.

Unless otherwise indicated, all numbers expressing feature sizes, amounts, and physical properties used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numbers set forth are approximations that can vary depending upon the desired properties using the teachings disclosed herein.

DETAILED DESCRIPTION

Abrasives are commonly used to grind, sand, polish, and otherwise treat the surfaces of materials such as wood, metal, plastic, and painted and coated surfaces. Abrasive articles include coated abrasives, lapping coated abrasives, non-woven abrasives, and buffing articles, for example. These abrasive articles can be in various forms, such as a disc, a sheet, or a polygonal element. In some embodiments, an abrasive sheet is affixed to or integrally formed with a back-up support pad of resilient material. Moreover, abrasive articles may optionally contain holes or slits to aid in dust and residue extraction.

One embodiment of a device of the present disclosure is an electrically, pneumatically, or hydraulically powered surface treatment or abrading tool. The term “abrading” as used herein includes all methods of material removal due to frictional contact between contacting surfaces in relative motion, such as grinding, sanding, polishing, burnishing, or refining. The relative motion produced by the tool can be a vibratory, straight line, rotary, orbital, or random orbital motion, for example.

A rotary tool simply rotates abrasive disc about a fixed axis. This may cause the abrasive face of the disc to abrade deeper scratches into the surface of the workpiece, because the abrasive face follows the same path during each rotation of the disc. This regular rotary motion can result in deeper, coarser cutting, which may be desirable for some applications, but not for others.

An orbital tool moves the abrasive disc in a revolutionary pattern. Another type of abrasive apparatus of the present disclosure is a random orbital tool. This type of tool combines a rotary and orbital motion which results in a random motion of the abrasive disc with respect to the workpiece. Such a motion is desirable because a random motion of the abrasive disc decreases the likelihood that a regular pattern of deeper scratches will be cut into the surface of the workpiece. As a result, a finer finish may be obtained on the surface of the workpiece.

One method of abrading a workpiece involves moving an abrasive article while urging the abrasive against a workpiece. An abrasive article is generally any cutting device that will level a defect in or on a workpiece. By “abrasive disc” it is meant that the abrasive article is typically circular; however, other shapes (e.g., hexagonal, octagonal or scalloped, for example) can be used without departing from the spirit and scope of the disclosure, and are included within the term “disc.” For example, U.S. Pat. No. 4,920,702 (Kloss et al.) discloses a portable tool having, in one embodiment, a generality triangular back-up pad and abrasive disc that are vibrated.

FIG. 1 is a perspective view of one embodiment of a surface treatment apparatus 10 of the present disclosure. In an exemplary embodiment, pneumatic tool 10 includes handle portion 12 and abrading head 14. In an exemplary embodiment, handle portion 12 includes compressed air inlet 15, inlet adjustment valve 16, housing 18, valve plug 20, cap lock 22, cap 24, and hand-operated throttle lever 26. Abrading head 14 includes stabilizer 29 attached to angle housing 32 by band 34. Band 34 is held together by screws that are covered by cap 36. Stabilizer 29 includes movable portion 30, fixed portion 31, and springs 76 (see FIGS. 3a and 3b). While stabilizer 29 is shown as a continuous cylindrical housing or shroud, it is contemplated that other shapes or noncontinuous forms may be used.

In the illustrated embodiment, tool 10 is pneumatic and is connected to an air compressor (not shown). In another embodiment, tool 10 is connected to a different power source such as a hydraulic or electrical source. In some embodiments, tool 10 incorporates its own power source (such as a battery) and does not require connection to an external power source.

FIG. 2 is a cross-sectional view of tool 10 along line 2-2 of FIG. 1. For operation, inlet 15 is attached to power source such as a compressed air source (not shown). Valve 16 may be used to adjust the effective inlet opening. Throttle lever 26 is pivotable about spring pin 38. Depression of throttle lever 26 causes upward movement of throttle valve 40 and compression of spring 42, thereby allowing air flow through air regulator 44. The compressed air causes rotation of a motion generating device such as rotor 46, which interlocks with gear 48 to result in rotation of shaft 50 on journal bearing 52 about axis A-A. Changing the air volume flowing through valve 16 varies the speed of the rotor 46. At the end of abrading head 14 is abrasive disc 72. Tool 10 typically orbits the abrasive disc 72 at speeds between 3,000 and 20,000 revolutions per minute, and more typically between 7,500 and 10,000 revolutions per minute.

FIG. 3a is an enlarged cross sectional view of one embodiment of abrading head 14 of the tool 10, in a disengaged position. As shown in more detail, an exemplary embodiment of abrading head 14 includes balancer 56 attached by screw 58. Axis B-B of second shaft 60 moves with ball bearings 62 and 64. Axis B-B is parallel to axis A-A (see FIG. 2), but may be spaced from axis A-A during the orbital motion of abrasive disc 72. In an exemplary embodiment, second shaft 60 revolves around axis A-A. In one embodiment, a maximum displacement of axis B-B from axis A-A is about 1.5 mm.

Balancer 56 assists in effecting revolution of second shaft 60 about axis A-A. The speed of rotation of second shaft 60 may depend on parameters such as the amount of force applied to the tool, the material composition and topography of the workpiece, and the abrasive that is used. For example, under very light pressure, second shaft 60 may revolve relatively quickly whereas under a very high load, second shaft 60 may revolve relatively slowly.

In one embodiment, backing plate 66 is attached to the end of abrading head 14 by screws 68. Backing plate 66 typically includes force control device attachment means 70 for attaching force control device 74. A force control device 74 may be affixed to a backing plate 66 in a number of different ways. For example, a pressure sensitive adhesive (PSA) (see U.S. Pat. No. 3,849,949 (Steinhauser et al.), for example); interengaging fastener members, such as a multiplicity of hook portions on the backing plate and a multiplicity of loop portions on the force control device (see U.S. Pat. No. 4,609,581 (Ott), for example); and cooperating male and female fastener members, may be used. Another suitable attachment system is disclosed in commonly assigned U.S. Pat. No. 6,988,941, entitled “Engaging assembly for abrasive back-up pad,” hereby incorporated by reference. In the illustrated embodiment, back-up pad 73 and abrasive disc 72 are in turn attached to force control device 74.

In the illustrated embodiment, skirt 28 is attached to angle housing 32 and backing plate 66 to prevent rotation of abrasive disc 72, thereby resulting in an orbital motion of abrasive disk 72. In another embodiment, skirt 28 may be omitted, and the tool 10 will then exhibit a random orbital motion. The general operating principles of a random orbital tool are further described in commonly assigned U.S. Pat. No. 5,377,455, entitled “Automated random orbital abrading system and method,” and U.S. Pat. No. 4,660,329, entitled “Powered abrading tool,” the contents of both of which are hereby incorporated by reference. It is contemplated that tools using the teachings of the present disclosure may also use other types of motion, such as rotary, straight-line or vibratory motions.

FIG. 3a shows tool 10 in a disengaged position. In this position, springs 76 of stabilizer 29 are relaxed. A bottom surface of movable portion 30 of stabilizer 29 extends below abrasive disc 72. FIG. 3b is an enlarged cross sectional view of the abrading head 14 of the tool 10 in an engaged position. This position is achieved when a tool operator presses movable portion 30 of stabilizer 29 against a workpiece surface 78, thereby compressing springs 76 to allow abrasive disc 72 to contact workpiece surface 78. On stabilizer 29, movable portion 30 and fixed portion 31 are slidably connected by means such as the use of pins.

As illustrated, force control device 74 is mechanically tuned by a spring to cooperate with stabilizer 29. Stabilizer 29 and force control device 74 are constructed so that even if an operator applies more pressure than needed, the construction prevents abrasive disc 72 from contacting workpiece surface 78 with too much force. Thus, stabilizer 29 and force control device 74 work cooperatively to prevent a force of contact between the abrasive disc 72 and the workpiece surface 78 from exceeding a set level. In one embodiment, the force control device 74 has a maximum force control level, and the set level is less than the maximum force control level.

In some embodiments, the springs of the stabilizer exert a greater force than the force control device. In an exemplary embodiment, the springs of the stabilizer may exert about 5 pounds of force, equal to the set level, while the spring of the force control device may exert about 3 pounds of force. This arrangement ensures full contact between the abrasive disc and the workpiece surface (i.e., a substantial portion of the abrasive disc contacts the workpiece), and ensures that the desired pressure (i.e., the “set level”) is transmitted to workpiece surface, even if the springs of the stabilizer are not completely compressed.

In another embodiment, the springs of the stabilizer exert a force that is equal to or greater than the force control device. FIG. 3b shows an exemplary embodiment having springs of the stabilizer that exhibit a force that is greater than the force control device. At the engaged positioned shown in FIG. 3b, springs 76 are fully compressed, while the spring of force control device 74 is somewhat, but not fully, compressed. At a point where springs 76 are fully compressed, additional force applied by the operator cannot transfer to the interface between abrasive disc 72 and the workpiece surface 78. Thus, stabilizer 29 and force control device 74 work cooperatively to prevent a force of contact between the abrasive disc 72 and the workpiece surface 78 from exceeding that level.

In some embodiments, the stabilizer is fixed relative to the tool and does not comprise a spring. When not in use, the force control device is positioned such that the abrasive disc will extend beyond the stabilizer. During use, the fixed stabilizer prevents the springs (or other force control means) of the force control device from being fully compressed such that any additional force applied by the operator cannot transfer to the interface between abrasive disc and the workpiece surface.

In an exemplary embodiment, force control device 74 includes a spring having a certain spring constant. In other embodiments, force control device 74 may be formed from foam, rubber, neoprene, or other material that has a resilient property. While the illustrated embodiment includes a mechanically tuned force control device 74, it is contemplated that the force control device can also be pneumatically tuned using air pressure resistance or hydraulically tuned using an oil valve, for example.

In one embodiment, stabilizer 29 comprises a two-part cylindrical housing surrounding the abrasive disc 72. In an exemplary embodiment, stabilizer 29 prevents tipping of tool 10 and uneven application of abrasive disc 72 to workpiece surface 78. In exemplary embodiments, stabilizer 29 is made of a material such as rubber or plastic that will not itself scratch or otherwise damage workpiece surface 78. While the illustrated mechanism of stabilizer 29 is mechanically tuned to the set level by spring 76, it is also contemplated that stabilizer 29 may be a pneumatically or hydraulically controlled device, for example.

The illustrated embodiment includes back-up pad 73 attached to force control device 74 and an abrasive disc 72 in turn attached to back-up pad 73. The forms of attachment can be the same as or different from those discussed with respect to force control attachment means 70.

Back-up pad 73 may be constructed of a compressible, resilient material, including but not limited to vinyl, cloth, foam such as open or closed cell polymeric foams (such as soft closed cell neoprene foam, open cell polyester foam, polyurethane foam, reticulated or non-reticulated slabstock foams), rubber, or porous thermoplastic polymers, for example, depending on the desired stiffness, conformability, and other properties. Typical polyurethane-based foams include toluene diisocyanate (TDI) based foam and methylene di (or bis) phenyl diisocyanate (MDI) based foam. A softer and/or thicker back-up pad 73 can result in a finer finish and better conform to surface curves or irregularities in workpiece surface 78. In another embodiment, back-up pad 73 may be eliminated and abrasive disc 72 may be attached directly to force control device 74.

Suitable exemplary abrasive articles for abrasive disc 72 are disclosed in commonly assigned U.S. Pat. No. 6,231,629, entitled “Abrasive article for providing a clear surface finish on glass;” U.S. Pat. No. 6,312,484, entitled “Nonwoven abrasive articles and method of preparing same;” and U.S. Pat. No. 5,454,844, entitled “Abrasive article, a process of making same, and a method of using same to finish a workpiece surface,” all hereby incorporated by reference. Other suitable abrasive discs are commercially available from 3M Company, St. Paul, Minn., under the trade designations “Trizact” and “Finesse-it.”

For some applications, it is desirable that a small abrasive disc 72 be used so that the sanded spot requires less subsequent buffing. In an exemplary embodiment, abrasive disc 72 is a round or scalloped edge disc with a diameter between 0.5 inch (12.7 mm) and 1.0 inch (25.4 mm).

FIG. 4 is a perspective view of an embodiment of a tool 10 of the present disclosure, including hoses for lubricant application and removal. In one embodiment, tool 10 includes a lubricant application hose 80 and a vacuum hose 82. Lubricant application hose 80 applies the correct amount of a sanding lubricant, such as water, to keep the abrasive disc 72 from loading up with abraded material from the workpiece surface 78. This is desirable because a loaded abrasive surface is less effective. In one embodiment, the lubricant application device applies lubricant to the abrasive surface 72 or the workpiece surface 78 as pressure is applied to stabilizer 29.

The illustrated embodiment includes a suction or vacuum device that operates through vacuum hose 82 to remove the abrasion residue and/or lubricant during or after abrasion. If such residue or lubricant is not removed, it can contaminate a buffing pad that is subsequently used, thereby potentially resulting in unwanted scratches during the buffing process.

FIG. 5a is an enlarged cross sectional view of one embodiment of an abrading head of a tool in an “off” position, the abrading head including an on/off switch 84. FIG. 5b is an enlarged cross sectional view of the abrading head of FIG. 5a in an “on” position. Switch 84 may be used in addition to, or instead of, throttle lever 26 to control operation of tool 10. In the “off” position illustrated in FIG. 5a, switch 84 rests above spring 76, and pin 83 of switch 84 is removed from recess 85 of stationary portion 31 of stabilizer 29. As a tool operator depresses movable portion 31 of stabilizer 29 against a workpiece surface 78 (as shown in FIG. 5b), spring 76 and switch 84 are pushed upward, thereby pushing pin 83 into recess 85. In the “on” position of FIG. 5b, pin 83 of switch 84 is fully inserted into recess 85, thereby activating switch 84 to move abrasive disc 72.

In one embodiment, abrasive disc 72 moves as long as switch 84 is activated. In another embodiment, switch 84 is connected to a timer, computer, or other processor that automatically operates moves abrasive disc 72 for a specified period of time, for example about three seconds. If more operator control is desired, an indicator light or audible buzzer can instead be used to alert the operator that a specified amount of time has elapsed.

In an exemplary embodiment, movable portion 30 of stabilizer 29 also serves as a defect locator. By surrounding the defect on workpiece surface 78 with movable portion 30, an operator can be assured that the defect will be treated. In an exemplary embodiment, movable portion 30 is formed from a transparent material that allows an operator to see through movable portion 30 to confirm that the workpiece defect is within the area to be abraded.

In a case with purely rotary motion, the area of abrasive disc 72 may be about the same as the area within movable portion 30. In a case with orbital, random orbital, or other motion, the area of abrasive disc 72 may be smaller than the area within movable portion 30. In other embodiments, a defect locator may be provided in the form of a light or laser image that projects onto the workpiece surface 78, for example.

FIG. 6a is a perspective view of an embodiment of a tool 10 of the present disclosure, including a projected light defect locator 86. FIG. 6b is an enlarged cross sectional view of the abrading head 14 of FIG. 6a. In the illustrated embodiment, defect locator 86 is attached to stabilizer 29. Defect locator 86 projects visible light pattern 88 onto workpiece surface 78. In another embodiment, visible light pattern 88 is projected from within movable portion 30 of stabilizer 29. By positioning defect 90 within the visible light pattern 88, an operator can be assured that defect 90 will be abraded by abrasive disc 72. Visible light pattern 88 can also have other shapes, such as a bulls eye or intersecting cross hairs.

All patents, patent applications, provisional applications, and publications referred to or cited herein are incorporated by reference in their entirety, including all figures and tables, to the extent they are not inconsistent with the explicit teachings of this specification.

It should be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application. For example, while tool 10 is illustrated as an angled tool, it is also contemplated that tool 10 may be a palm held tool. Additionally, while tool 10 is described in some embodiments as a handheld tool, it is also contemplated that tool 10 may be robotically or otherwise automatically operated.

Claims

1. A surface treatment apparatus for abrading a workpiece surface, the apparatus comprising:

a motion generating device configured to move an abrasive disc;

a stabilizer; and a

a force control device; wherein the stabilizer and the force control device work cooperatively to prevent a force of contact between the abrasive disc and the workpiece surface from exceeding a set level.

2. The surface treatment apparatus of claim 1 wherein the force control device exerts the set level of force and the stabilizer exerts a second level of force, wherein the second level is greater than the set level.

3. The surface treatment apparatus of claim 1 wherein the force control device has a maximum force control level, and wherein the set level is less than the maximum force control level.

4. The surface treatment apparatus of claim 1 wherein the force control device comprises a spring.

5. The surface treatment apparatus of claim 1 wherein the force control device is a resilient material selected from the group consisting of foam, rubber, or neoprene.

6. The surface treatment apparatus of claim 1 wherein the stabilizer comprises a housing surrounding the abrasive disc.

7. The surface treatment apparatus of claim 6 wherein the stabilizer comprises:

a fixed portion; and

a movable portion.

8. The surface treatment apparatus of claim 1 wherein the stabilizer comprises a spring.

9. The surface treatment apparatus of claim 1 further comprising an abrasive disc.

10. The surface treatment apparatus of claim 9 wherein at the set level, a bottom surface of the stabilizer and the abrasive disc both contact the workpiece surface.

11. The surface treatment apparatus of claim 9 wherein an area of the workpiece covered by a movement of the abrasive disc is nearly equal to an area within the stabilizer.

12. The surface treatment apparatus of claim 1 wherein the stabilizer is fixed relative to the motion generating device.

13. The surface treatment apparatus of claim 1 further comprising a timer.

14. The surface treatment apparatus of claim 1 further comprising a lubricant applicator.

15. The surface treatment apparatus of claim 1 further comprising a vacuum.

16. The surface treatment apparatus of claim 1 further comprising a projected light locator.

17. The surface treatment apparatus of claim 16 wherein the projected light locator is configured to project a circular pattern.

18. The surface treatment apparatus of claim 1 wherein the apparatus is a hand tool.

19. The surface treatment apparatus of claim 1 further comprising a power source.

20. The surface treatment apparatus of claim 1 wherein the power is a battery.