US3371451A - Shifting mechanism for dual-action power-operated abrading tool - Google Patents

Description

March 5, 1968 5, ENDERS 3,371,451

SHIFTING MECHANISM FOR DUAL-ACTION I POWER-OPERATED ABRADING TOOL Filed March 28, 1966 2 Sheets-Sheet 1 INVENTOR SHERWOOD G. ENDERS BY ,gnd.

ATTORNEY March '5, 1968 s. G. ENDERS SHIFTING MECHANISM FOR DUAL -ACTION POWER-OPERATED ABRADING TOOL Filed March 28, 1966 2 Sheets-Sheet 2 INVENTOR ATTORNEY United States Patent 3 3711. 451 srnrrmo Mncnariusrfi non nUaL-Acrrort POWER-OPERATEE AERADENG TOUL faherwood G. Enders, Bowleys Quarters, Md assignor to The Black and Decker Manufacturing Company,

Toe/son, Md, a corporation of Maryland Filed Mar. 28, M66, Ser. No. 538,004 7 Claims. ((15. 5l--17t)) The present invention relates to a shifting mechanism for a dual-action portable electric sander, whereby the tool platen may have either a substantailly straight-line reciprocation or else an orbital reciprocation; and more particularly, the present invention constitutes an improvement over the mechanism disclosed in the co-pending Sheps application, Ser. No. 538,005, filed Mar. 28, 1966, entitled, Dual-Action Power-Operated Abrading Tool, and assigned to the assignee of the present invention.

The present invention may be used in conjunction with a portable power-operated abrading tool, such as a portable electric sander, of the type comprising a housing, a platen resiliently mounted below the housing, a pivot arm between the housing and the platen, the pivot arm having a pair of ends, one of which is pivotally mounted on the platen and the other of which is free, and a driving eccentric connected to the pivot arm intermediate the ends of the arm, the driving eccentric being journaled or disposed along a substantially vertical axis, whereby the pivot arm oscillates substantially in a horizontal plane above the platen, and whereby the platen has a substantially straight-line reciprocation. If the free end of the pivot arm is restrained against further oscillation, such as by exerting a vertical clamping force as described in the aforesaid Sheps application, then the straight-line reciprocation of the platen is converted into an orbital reciprocation; and conversely, when the vertical clamping force is released and the free end of the pivot arm is no longer restrained, then the orbital reciprocation of the platen is converted back into a substantially straight-line reciprocation.

The present invention constitutes an improvement in the guiding and selective restraining mechanism for the free end of the oscillating pivot arm; and this improvement comprises, in combination, a bearing guide having a slot receiving the free end of the pivot arm, means supporting the bearing guide on the platen and journaling the same for pivotal movement about a substantially horizontal axis, whereby the slot in the bearing guide angularly adjusts to the free end of the pivot arm, and means carried on the platen for selectively restraining the free end of the pivot arm against oscillation in a horizontal plane, whereby the straight-line reciprocation of the platen is converted into an orbital reciprocation.

It is an object of the present invention to provide an improved guiding and restraining mechanism, wherein the bearing guides for the free end of the oscillating pivot arm may aline themselves, that is, angularly adjust to the pivot arm, and wherein the clamping means for selectively restraining the free end of the pivot arm comprises a clamping member which is separate from the bearing guides, thereby resulting in an improved mechanism having the advantages of increased reliability and durability over an extended period of operation.

In accordance with a preferred embodiment of the present invention, a threaded stud is secured on the platen and projects vertically therefrom. A pair of bearing guide supports are piloted on the stud. These bearing guide supports are substantially identical to one another and comprise a top bearing guide support and a bottom bearing guide support, the latter being supported upon the platen. The bearing guide supports have respective curved portions. The curved portion of one is complementary to 337L451 Patented Mar. 5, 1968 and confronts the curved portion of the other so as to form a generally cylindrical bearing seat. A bearing guide is journaled in the seat and is restrained against axial displacement therefrom. The bearing guide has a slot, substantially in a horizontal plane, for receiving the free end of the pivot arm. Preferably, a pair of bearing guides are provided, spaced apart from one another. With this arrangement, the slots in the bearing guides angularly adjust, individually, to the free end of the pivot arm. A clamp member is piloted on the stud above the top bearing guide support and has a clamping portion disposed between the spaced-apart bearing guides and above the free end of the pivot arm. A lever has a threaded portion engaging the stud above the clamp member, thereby selectively exerting a vertical clamping pressure which restrains the free end of the pivot arm between the clamp member portion and the bottom surfaces of the slots in the respective bearing guides. Preferably, a spring member is piloted on the stud between the top bearing guide support and the clamp member, thereby preventing substantial contact between the clamp member portion and the free end of the pivot arm in the normal unrestrained position of the pivot arm.

In accordance with another aspect of the present invention, the improved structure comprises, in combination, a first member having a means for slidably supporting the free end of the pivot arm, means supporting the first member on the platen and journaling the same for pivotal movement about a substantially horizontal axis, whereby the first member angularlty adjusts to the free end of the pivot arm, a second member for selectively clamping the free end of the pivot arm against the first member, and resilient means constantly urging the second member away from the free end of the pivot arm in its unrestrained position.

These and other objects of the present invention will become apparent from a reading of the following specification, taken in conjunction with the enclosed drawings, in which:

FIGURE 1 is a side elevation of a typical portable power-operated abrading tool with which the teachings of the present invention may find particular utility;

FIGURE 2 is an enlarged top plan view of the platen assembly, the conventional four rubber posts being shown in section;

FIGURE 3 is a section view, taken along the lines 33 of FIGURE 2, the four rubber posts being omitted for clarity of illustration, and the view showing the manner in which the pivot arm is pivotally mounted on the platen, the manner in which the driving eccentric is preferably journaled in a bearing retained intermediately of the ends of the pivot arm, and the improved structure of the present invention for guiding and selectively restraining the free end of the pivot arm;

FIGURE 4 is a section view, taken along the lines 44 of FIGURE 2, showing the manner in which the free end of the pivot arm is guided in the bearing guides, and further showing the manner in which the clamp member portion exerts a vertical clamping pressure to restrain the free end of the pivot arm against the lower surfaces of the slots in the respective bearing guides;

FIGURES 5a and 5b illustrate the manner in which the bearing guides and the respective slots therein may angularly adjust to (or pivot in response to) the posi tion of the free end of the oscillating pivot arm;

FIGURE 6 is an exploded perspective of the improved structure of the present invention; and

FIGURE 7 is a modification illustrating the manner in which the bearing guide may be resiliently supported in the bearing guide supports for the purpose of adjusting to the position of the pivot arm in a manner equivalent to the embodiment of FIGURES 5a and 5b.

With reference to FIGURE 1, there is illustrated a portable electric sander or abrading tool in which the improved structure of the present invention may be incorporated. The tool 10 generally comprises a motor housing 11, a flanged skirt 12, a rear handle 13 having an electric switch 14 for energization of the unit from an electrical line cord 15, a front handle 16 to assist in guiding and controlling the tool, and a platen assembly, denoted generally as at 17, and resiliently supported below the housing.

With reference to FIGURES 2 and 3, the platen assembly 17 includes a conventional pad 18 provided with a sheet-metal backing 19. The pad 18 is resiliently mounted to the tool housing by means of four rubber posts 20, which are retained to the backing 19 by means of respective brackets 21. Each bracket 21 has a curved portion 22 which journals a cylindrical rod 23. The rod 23 has spaced-apart knurled portions 24 and a screwdriver slot 25 at its ends. With this arrangement, the rod 23 provides a convenient clamp for the typical abrasive paper used with a tool of this type. The manner in which the rubber posts 20 are retained in the housing of the tool, the manner in which the bracket .21 secures or traps a respective pair of posts to the backing 1'9, and the manner in which the paper clamp subassembly is provided by the rod 23, form no part of the present invention, but rather are described in detail in the co-pending Enders application, Ser. N0. 348,124, filed Feb. 28, 1964, entitled Oscillating Piaten for Abradin-g Tool and assigned to the assignee of the present invention, now Patent No. 3,336,- 702, dated Aug. 22, 1967.

With reference again to FIGURES 2 and 3, a pivot arm 26 is disposed above the platen and functions as an intermediate driving member between the driving eccentric and the platen. The pivot arm ha one end pivoted to the platen, and carries a bearing intermediate its ends for journaling a driving eccentric. With this arrangement, the free end of the pivot arm, being unrestrained, oscillates in a generally horizontal plane above the platen, and the platen has a substantially straightdine reciprocation. In accordance with the present invention, the free end of the pivot arm is slidably guided within one or more bearing guides, and the bearing guides are preferably journaled for pivotal movement in order to adjust to the free end of the pivot arm. Means are also provided for restraining the free end of the arm, thereby converting the straight-line reciprocation of the platen into an orbital reciprocation.

With particular reference to FIGURE 3, the preferred means for pivoting the front end of the pivot arm 26 to the platen is as follows: An internally-threaded stud 27 is secured to the platen by means of a screw 28, the latter also securing the respective bracket 21 to the platen. A flanged bushing 29 is piloted on the stud 27. The flanged bushing receives the collar portion 26a of the pivot arm 26. A washer retainer 30 is also piloted on the stud above the collar 26a. Completing the assembly, the retainer washer 30 is retained by means of a washer 31 and screw 32, the latter being received within the stud 27. Both the flanged bushing 29 and the retainer washer 30 are preferably molded of an anti-friction plastic material. Any suitable means, however, may be used to pivot the front end of the pivot arm 26 to the platen.

With reference again to FIGURE 3, the preferred means for driving the pivot arm 26 is as follows: A bearing retainer 33 is secured intermediately the ends of the pivot arm 26 by means of screws 34. The bearing retainer 33 has a partially-completed spherical seat 33a for receiving a spherical sleeve bearing 35. A driving eccentric 36 is journaled within the bearing 35 along a substantially vertical axis, and the driving eccentric 36 is connected with the motor (not shown) of the tool. The manner of mounting the bearing retainer 33, the manner in which the bearing retainer accommodates usage of a spherical bearing 35, and the related structure of the driving eccentric 36, form no part of the present invention,

4 but rather are described in detail in the Enders Patent 3,199,251 entitled Driving Mechanism for Abrading Tool, issued Aug. 10, 1965, and assigned to the assignee of the present invention.

With reference again to FIGURES 2 and 3, and with further reference to FIGURES 6, the improved structure of the present invention is a follows: A threaded stud 37 is secured on the other end of the pad 1 8 by means of a screw 38, the latter also securing the respective bracket 21 to the pad. A spacer washer 39 is piloted on the lower portion of the stud 37. A pair of bearing guide supports (comprising a top bearing guide support 40 and a bottom bearing guide suport 41) are also piloted on the lower portion of the stud 37, and are retained between the spacer washer 39 and a shoulder 37a formed on the stud. The bearing guide supports 40, 41 have respective curved portions 42 and 43. Preferably, the respective curved portions 42, 43 of the bearing guide supports 40, 41 are interrupted, see FIGURE 2, so as to form spaced-apart curved portions. These curved portions are complementary to one another and confront one another to form respective seats for journaling respective bearing guides 44. In the particular embodiment shown in the drawings, two spaced bearing guides 44 are employed, one in each of the respective seats. The bearing guides 44 have slots 45 formed therein, and these slots 45 are substantially aligned with one another in a generally horizontal plane for receiving the raised lip portion 261) formed on the free end of the pivot arm 26. Preferably, the bearing guides 44 are formed of an anti-friction material and have respective flanges 46 for preventing axial displacement of the bearing guides 44 from their respective seats in the bearing guides supports 40, 41. Preferably, but no necessarily, the respective axes of the bearing guides 44 intersect one another so as to conform to the generally arcuate plan view, see FIGURE 2, of the raised lip 26]; on the free end of the pivot arm 26.

With reference to FIGURES 5a and 5b, it will be appreciated that the bearing guides 44 are journaled for pivotal movement about a substantially horizontal axis, and in this manner the respective slots 45 in the bearing guides 44 may angularly adjust, individually, to the raised lip 26b on the free end of the pivot arm 26. In a sense, the bearing guides 44 may be said to be self-alining in relation to the horizontally-disposed oscillating pivot arm 26. In FIGURES 5a and 5b, the extreme positions of the bearing guides 44 are shown for illustrative purposes. In FIGURE 5a, the bearing guide 44 has rotated clockwise, as viewed in the drawing, to accommodate the somewhat skewed position of the free end of the pivot arm 26. On the other hand, in FIGURE 51) the bearing 44 has rotated counterclockwise, as viewed in the drawing, to accommodate the reversely skewed position of the free end of the pivot arm 26. With this arrangement, the free end of the oscillating pivot arm 26 is smoothly guided in its unrestrained position, and the manner in which the bearing guides 44 are mounted on the platen relieves or compensates for any manufacturing variations or tolerance accumulations which might otherwise offset or unduly restrain the free end of the pivot arm.

In order to restrain the free end of the pivot arm, whenever desired for the purpose of shifting the reciprocation Of the platen into an orbital mode, a clamping means is provided which basically is separate from the bearing guides 44, the latter serving to slidably guide the free end of the arm. In accordance with the teachings of the present invention, a clamp washer 47 is piloted on an unthreaded portion of the stud 37 above the top bearing guide support 40. Preferably, the clamp washer 47 is integrally molded of a suitable anti-friction material. A clamp support 48, see FIGURE 6, is disposed above the clamp washer 47. The clamp support 48 has an aperture 48a receiving the collar 47a of the clamp Washer 47, and the clamp support 48 further has a pair of cars 49 which straddle the rear portion of the clamp washer 47. This prevents relative rotation between the clamp washer 47 and its clamp support 48. The clamp washer 47 has a clamping portion 50 which, see FIGURE 2, is received between the bearing guides 44. Completing the assembly, a lever 51 has a threaded portion, such as a Weld nut 52, received on the threaded portion of the stud 37 above the clamp support 48.

In operation, when the lever 51 is pivoted through an acute angle, the clamping portion 50 of the clamp washer 47 bears down upon the free end of the pivot arm 26, and as shown in FIGURE 4, the arm is retained between the clamping portion 50 and the bottom surfaces of the respective slots 45 in the bearing guides 44. This restrains the free end of the pivot arm, precludes further oscillation of the arm in a horizontal plane above the platen 17, and converts the substantially straight-line reciprocation of the platen into an orbital reciprocation, Conversely, when the lever 51 is pivoted in the reverse direction, the clamping portion 50 of the clamp washer 47 is lifted away from the free end of the pivot arm 26, the arm is in its normally unrestrained position, and the platen 17 has a substantially straight-line reciprocation.

In accordance with another feature of the present invention, a spring member 53 (which may be formed of sheet metal) is preferably piloted on the stud 37 and is lodged between the top bearing guide support 40 and the clamp washer 47. This provides a resilient means for preventing the clamping portion 50 of the clamp washer 47 (and the weight of it and its associated parts) from interfering with or otherwise restraining the free arm of the pivot arm 26 in its normally unrestrained position.

Preferably, as disclosed in the aforementioned copending Sheps application, a molded-plastic wrench member 54 is provided, see FIGURE 6, and the wrench 54 has a recess 55 engaging the end of the lever 51 for the purpose of actuating the lever.

With reference to FIGURE 7, a modification is illus trated, wherein the bearing guide 44 is resiliently mounted between the bearing guide supports 40 and 41' by means of a substantially U-shaped resilient member 56. This allows the bearing guide 44' to move, pivot, or cock slightly to accommodate the position of the free end of the oscillating pivot arm. The operation of the resiliently mounted bearing guide 44 is substantially equivalent to what has been described previously with reference to the embodiment of FIGURE 6.

Obviously, many modifications may be made without departing from the basic spirit of the present invention; and accordingly, within the scope of the appended claims, the invention may be practiced other than has been specifically described herein.

I claim:

1. In a portable power-operated abrading tool having a housing, a platen resiliently mounted below the housing, a pivot arm between the housing and the platen, the pivot arm having a pair of ends, one of which is pivotally mounted on the platen and the other of which is free, a bearing mounted on the pivot arm intermediate its ends, and a driving eccentric journaled in the bearing along a vertical axis, whereby the pivot arm oscillates substantially in a horizontal plane above the platen, and whereby the platen has a straight-line reciprocation, the improvement which comprises:

(a) a bearing guide having a slot receiving the free end of the pivot arm;

(b) means supporting the bearing guide on the platen and journaling the same for pivotal movement about a substantially horizontal axis, whereby the slot in the bearing guide angularly adjusts to the free end of the pivot arm; and

(c) means carried on the platen for selectively restraining the free end of the pivot arm against oscillation in a horizontal plane, whereby the straight-line reciprocation of the platen is converted to an orbital reciprocation.

2. In a portable power-operated abrading tool having a housing, a platen resiliently mounted below the housing, a pivot arm between the housing and the platen, the pivot arm having a pair of ends, one of which is pivotally mounted on the platen and the other of which is free, a bearing mounted on the pivot arm intermediate its ends, and a driving eccentric journaled in the bearing along a vertical axis, whereby the pivot arm oscillates substantially in a horizontal plane above the platen, and whereby the platen has a straight-line reciprocation, the improvement in means for guiding the free end of the pivot arm and for selectively restraining the same against further movement, thereby converting the straight-line reciprocation of the platen to an orbital reciprocation, which improvement comprises:

(a) a pair of spaced-apart bearing guides having respective slots alined with one another in a horizontal plane and receiving the free end of the pivot arm;

(b) means supporting the bearing guides on the platen and journaling the same for pivotal movement about respective substantially-horizontal axes, whereby the slots in the bearing guides individually angularly adjust to the free end of the pivot arm; and

(c) a clamp member carried on the platen and having a portion disposed between the spaced-apart bearing guides for selectively restraining the free end of the pivot arm.

3. in a portable power-operated abrading tool having a housing, a platen resiliently mounted below the housing, a pivot arm between the housing and the platen, the pivot arm having a pair of ends, one of which is pivotally mounted on the platen and the other of which is free, a bearing mounted on the pivot arm intermediate its ends, and a driving eccentric journaled in the bearing along a vertical axis, whereby the pivot arm oscillates substantially in a horizontal plane above the platen, and whereby the platen has a straight-line reciprocation, the improvement which comprises:

(a) a threaded stud secured on the platen and projecting vertically therefrom;

(b) a pair of bearing guide supports piloted on the stud;

(c) said bearing guide supports being substantially identical to one another and comprising a top bearing guide support and a bottom bearing guide support, the latter being supported by the platen;

(d) said bearing guide supports having respective spaced-apart curved portions, the curved portions of one being complementary to and confronting the curved portions of the other to form a pair of spacedapart cylindrical bearing seats;

(e) a pair of respective cylindrical bearing guides journaled in the bearing seats and restrained against axial displacement therefrom;

(f) said bearing guides having respective slots, alined with one another in a substantially horizontal plane, and receiving the free end of the pivot arm, whereby the slots in the bearing guides individually angularly adjust to the free end of the pivot arm;

(g) a clamp member piloted on the stud above the top bearing guide support and having a clamping portion disposed between the spaced-apart bearing guides and above the free end of the platen; and

(h) a lever having a threaded portion engaging the stud above the clamp member, thereby selectively exerting a vertical clamping pressure on the free end of the pivot arm.

4. The improvement of claim 3, wherein:

(a) the bearing guides are journaled for pivotal movement about respective axes which intersect one another.

5. The improvement of claim 3, wherein:

(a) a clamp support member is piloted on the stud between the clamp member and the lever;

(b) said clamp support member being keyed to the clamp member to prevent relative rotation therebetween.

6. The improvement of claim 3, wherein:

(a) a spring member is piloted on the stud between the top bearing guide support and the clamp member, thereby preventing substantial contact between the clamp member portion and the free end of the pivot arm in its unrestrained position.

7. In a portable power-operated abrading tool having a housing, a platen resiliently mounted below the housing, a pivot arm between the housing and the platen, the pivot arm having a pair of ends, one of which is pivotally mounted on the platen and the other of which is free, a bearing mounted on the pivot arm intermediate its ends, and a driving eccentric journaled in the bearing along a vertical axis, whereby the pivot arm oscillates substantially in a horizontal plane above the platen, and whereby the platen has a straight-line reciprocation, the improvement in means for guiding the free end of the pivot arm and for selectively restraining the same against further movement, thereby converting the straight-line 8 reciprocation of the platen to an orbital reciprocation, which improvement comprises:

(a) a first member having means for slidably supporting the free end of the pivot arm; (b) means supporting the first member on the platen and journaling the same for pivotal movement about a substantially horizontal axis, whereby the first member angularly adjusts to the free end of the pivot arm; (c) a second member for selectively clamping the free end of the pivot arm against the first member; and (d) resilient means constantly urging the second member away from the free end of the pivot arm in its unrestrained position.

References Cited UNITED STATES PATENTS 2,885,833 5/1959 Neff 51-17O LESTER M. SWINGLE, Primary Examiner.

Claims (1)

1. IN A PORTABLE POWER-OPERATED ABRADING TOOL HAVING A HOUSING, A PLATEN RESILIENTLY MOUNTED BELOW THE HOUSING, A PIVOT ARM BETWEEN THE HOUSING AND THE PLATEN, THE PIVOT ARM HAVING A PAIR OF ENDS, ONE OF WHICH IS PIVOTALLY MOUNTED ON THE PLATEN AND THE OTHER OF WHICH IS FREE, A BEARING MONTED ON THE PIVOT ARM INTERMEDIATE ITS ENDS, AND A DRIVING ECCENTRIC JOURNALED IN THE BEARING ALONG A VERTICAL AXIS, WHEREBY THE PIVOT ARM OSCILLATES SUBSTANTIALLY IN A HORIZONTAL PLANE ABOVE THE PLATEN, AND WHEREBY THE PLATEN HAS A STRAIGHT-LINE RECIPROCATION, THE IMPROVEMENT WHICH COMPRISES: (A) A BEARING GUIDE HAVING A SLOT RECEIVING THE FREE END OF THE PIVOT ARM; (B) MEANS SUPPORTING THE BEARING GUIDE TO THE PLATEN AND JOURNALING THE SAME FOR PIVOTAL MOVEMENT ABOUT A SUBSTANTIALLY HORIZONTAL AXIS, WHEREBY THE SLOT IN THE BEARING GUIDE ANGULARLY ADJUSTS TO THE FREE END OF THE PIVOT ARM; AND (C) MEANS CARRIED ON THE PLATEN FOR SELECTIVELY RESTRAINING THE FREE END OF THE PIVOT ARM AGAINST OSCILLATION IN A HORIZONTAL PLANE, WHEREBY THE STRAIGHT-LINE RECIPROCATION OF THE PLATEN IS CONVERTED TO AN ORBITAL RECIPROCATION.

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