US2282043A - Rubbing machine - Google Patents

Description

y 1942- G. H. EKSTROM 2,282,043

RUBBING MACHINE Filed Nov. 8, 1939 UNITED STATES PATENT OFFICE RUBBING MACHINE Gustaf H. Ekstrom, Rockford, Ill., assignor to Sundstrand Machine Tool (30., Rockford, Ill a corporation of Illinois Application November 8, 1939, Serial No. 303,354

19 Claims.

The present invention relates to a rubbing machine and more particularly to the rubbing shoe thereof.

Among the objects of the invention is to provide a novel and improved rubbing shoe having novel means for securely holding the abrasive sheet in place, such securing means affording a convenient, quick, and ready attaching and detaching of the abrasive sheet, with or without provision for making the shoe generally flexible for self-accommodation to the particular contour or shape of the surface being treated or operated upon.

Another object is to provide in a shoe of the character disclosed a novel clamping means which may be locked open for the removal and/ or the insertion of the end of the abrasive sheet to be removed and/or clamped, and readily unlocked to effect the clamping function.

A further object is to provide in a clamp in a shoe of the character disclosed a clamp operating element which is a permanent part of the clamp and which avoids the need of using a separate tool or the like that would easily become misplaced or lost.

Other objects, advantages, capabilities, features, and the like are comprehended by the invention, as will later appear and as are inherently possessed by the invention.

Referring to the drawing:

Fig. 1 is a perspective view of a rubbing shoe embodying the invention.

Fig. 2 is a fragmentary top plan View at an end of the device.

Fig. 3 is an end view in elevation of the inven- I tion.

Figs. 4, 5 and 6 are side views in elevation of a clamp end portion of the device showing different steps of the use of the device.

While the invention is susceptible of various modifications and alternative constructions, the embodiment shown in the drawing and described hereinafter is by way of preferred illustration only, and it is not intended that the invention be limited thereto or thereby, but it i intended to cover all modifications and alternative construc tions falling within the spirit and scope of the invention as defined by the appended claims.

Referring more in detail to the drawing, the embodiment chosen to illustrate the invention is shown as comprising a shoe having a pad I, such as felt, a flexible plate 2, which is preferably made of any kind of resilient material, surmounting the pad I and suitably attached thereto as by an adhesive, transverse yieldable pad elements 3, such as rubber or the like, on the plate 2 and suitably attached thereto, as by an adhesive, and an upper flexible plate 4, which also is preferably made of any kind of resilient material, surmounting the pads 3 and suitably attached thereto, as

by an adhesive. Over the lower surface of the pad I extends an abrasive sheet 5, such as sandpaper or the like, with the end portions of the sheet extending about the ends of the pad I and clamped in novel clamping means hereinafter described.

The novel clamping means comprises a pair of clamps, one at each end of the shoe andboth being identical in structure and function. Each clamping means comprises a transverse base plate 6 secured by rivets 1 to an end portion of the plate I, with a portion 8 of the plate 4 extending a short distance outwardly beyond the plate 6 as clearly shown in Figs. 4, 5 and 6.

The resilient part 9 of the clamp is in the form of a curved sheet, such as spring steel, to form approximately a hollow cylinder with a longitudinal opening for the jaws I0 and I I of the clamp. The portion I0 forms the relatively stationary or still jaw part of the clamp and is rigidly secured to the top of the plate Ii by the rivet I, as shown, this jaw I0 having outwardly extending teeth or serrations I2. The portion II forms the relatively movable or live jaw part of the clamp, which when in clamping or closed position and condition forcibly clamps the end portion I3 of the abrasive sheet against the serrated jaw I0. The lip edge portion I4 of the jaw II is of such extent as to enter the space I5 to put a crimp I6 in the end portion I3 of the abrasive sheet.

Within the part 9 and extending longitudinally thereof is anchored, on the top of the jaw II] by way of the rivets I, a locking cam member having an upwardly inclined cam part I! the upper edge of which may act a an abutment for the back portion of the spring part of the clamp member 9, as shown in Fig. 4. Also extending longitudinally within the part 9 is a key plate I8 the ends of which extend without the end openings of the part 9 and have upwardly extending arms I9 to the upper ends of which is secured a rod or bar 20 by which the key may be manipulated as later described.

The outer edge of the key plate I8 bears or fulcrunis against the inner surface of the jaw portion I I of the part 9 and has lugs 2I extending through aperture 2| provided in the jaw portion II, these lugsacting as pivot elements when the key is operated. The inner edge portion of the key plate has a lip 22, preferably rounded as shown, to bear against and slide over the outer surface of the cam H. In Figs. 1, 4 and 6, the lip 22 is shown at the upper portion of the cam I1, at which time the clamp is unlocked and is inclamping condition, and in Fig. 5 is shown at the lower portion of the cam IT, at which time the clamp is in locked and open condition, the jaw being held wide openfor the 'free withdrawal of the end portion of the worn abrasive sheet and for the free insertion of the end portion of the new abrasive sheet.

The shoe is designed to be connected to a rubbing machine having power means for actuating the shoes. Therefore, provision is made for the operative connection or attachment of the shoe to such machine, and the device herein disposition shown in Fig. 4 to the position shown in Fig. 5, the lugs 2! acting to raise and open the jaw I! with what may be termed a toggle action. When the lip reaches its lowermost position, it has passed what may be termed dead center so that the spring force of the jaw ll acting against the outer edge of the plate 58 is in a direction tending torock the plate upwardly about the line of contact of the lip 22 and cam II as an axis or fulcrum, thus'holding the clamp locked in open condition. The. user may then easily and quickly remove the worn abrasive sheet and replace it with a new sheet with the end portions 23 into the openings between the jaws of the clamps and opposite the spaces l5, as shown in Fig. 5. Then by pressing upwardly and outwardly on the bar 2b, the lock is released and the jaws clamp with a snap to clamp the end portion of the abrasive sheet between the jaws It] and H, and to form the crimp 16 in the space l5 between the serrated portion 12 of the jaw It and the plate extension 8, as shown in Fig. 6. During the unlocking action, the lip 22 slides upwardly over the cam ll, partly under the spring force of the jaw portion H and partly under the force applied by the user on the bar 253, to the position and relation shown in Fig. 6. It will-be noted, as shown in Figs. 4, 5 and 6, that the'cam I! is disposed in the position of a chord of the circle of the clamp body 9 diametrically opposite the jaw portion I! so that when the key [8 is moved to "cause its rear edge to slide over the surface of the cam 11 it will be made to pass by the line perpendicular to the cam II, which may be termed the dead center of the device.

Both the plates 2 and 4' are bendable or yieldable, so that as the shoe is applied to a contoured surface to be treated these plates will bend or .and not positive, there is always danger of the clamp prematurely snapping closed and injuring the other hand which is manipulating the abrasive sheet. By the present invention, after the clamps have been locked open, both of the users hands'are free to safely manipulate the abrasive sheet without any danger of injury to either hand.

Also in devices using clamps wherein the means for opening theclamp is a tool or the like which normally is free and independent, and is applied only at the time when the clamp is to be opened, such tool or element 'is easily lost or misplaced, often making it necessary to search for it with resultant loss of time. Moreover, there is a certain amount of time and care required to connect the tool to the clamp so that it will not slip out and cause injury to the user. In the present invention, the clamp opening or operating means is a permanent part of the clamping means, being a rigid part of the looking key member shown in the embodiment selected to illustrate the invention.

I claim as my invention:

1. In a rubbing shoe of the character disclosed having a plate over which an abrasive sheet extends with the ends thereof extending about the ends of the shoe, in combination, a clamping means for the abrasive sheet secured to each end of the plate, said clamping means comprising a still jaw secured to the plate, a live jaw, and a resilient portion connected between said jaws, a cam element located in fixed relation to the still jaw, and a key member fulcrumed against the live jaw and contacting the cam for sliding over said cam when the key member is forcibly rocked to move past dead center in the nature of a toggle action so as to open the jaws and hold them locked in open condition.

7 2. In a rubbing shoe of the character disclosed having a plate over which an abrasive sheet extends with the ends thereof extending about the ends of the shoe, in combination, a clamping means for the abrasive sheet secured to each end of the plate, said clamping means comprising a still jaw secured to the plate, a live jaw, and a resilient portion connected between said jaws, a cam element located in fixed relation to the still jaw, and a key member iulcrumed against the live jaw and contacting the cam for sliding over said cam when the key member is forcibly rocked to move past dead center in the nature of a toggle action so as to open the jaws and hold them locked in open condition, said still jaw having a clamping lip and said plate having an end portion spaced from said lip to provide a crimping space therebetween, and said live jaw having a lip adapted to extend into said space to form therein a crimp in the end portion of the abrasive sheet when being clamped between said jaws.

3. In a rubbing shoe of the character disclosed having a plate over which an abrasive sheet extends with the ends thereof extending about the ends of the shoe, in combination, a clamping means for the abrasive sheet secured to each end of the plate, said clamping means compris ing a sheet of spring material approximately in the form of a hollow cylinder withan elongated opening along a side thereof, one of the side portions of said sheet at said opening constituting the still jaw of the clamp and being rigidly secured to an end portion of said plate, the other of said side portions constituting the live jaw of the clamp and being normally in clamping contact with the still jaw under the resilient force of the remainder of said spring sheet, a lock cam member located within said spring sheet and secured at its lower portion to said still jaw and having an upwardly extending inclined cam portion. locking key located within said spring sheet and having its outward edge fulcrumed against said live jaw and its inward edge in contact with said inclined cam portion, and

an arm secured to said key for rocking said key about its fulcrum and to cause said key at its inward edge to slide along said cam for opening the jaws and for holding said jaws open.

4. In a rubbing shoe of the character disclosed having a plate over which an abrasive sheet extends with the ends thereof extending about the ends of the shoe, in combination, a clamping means for the abrasive sheet secured to each end of the plate, said clamping means comprising a sheet of spring material approximately in the form of a hollow cylinder with an elongated opening along a side thereof, one of the side portions of said sheet at said opening constituting the still jaw of the clamp and being rigidly secured to an end portion of said plate, the other of said side portions constituting the live jaw of the clamp and being normally in clamping contact with the still jaw under the resilient force of the remainder of said spring sheet, a lock cam located within said spring sheet in fixed relation to said still jaw and disposed in the position of a chord of the circle of the spring sheet inwardly opposite said live jaw, a locking key extending between said live jaw and said cam with the outward edge of the key fulcrumed against the live jaw and its inward edge in slidable contact with said cam, and an arm rigid with said key for manual rocking of the key about its fulcrum at the outward edge thereof and the sliding of said key at its inward edge over said cam so as to pass by the line perpendicular to said chord position of said cam for locking and holding locked said jaws in open position.

5. A rubbing shoe of the character disclosed comprising spaced plates of flexible material, yieldable pads between said plates, and a cushion pad at the outside of one of said plates, clamping means connected at the ends of the other of said plates for clamping the ends of an abrasive sheet comprising spaced plates of flexible material, 3

yieldable pads between said plates, and a cushion pad at the outside of one of said plates, clamping means connected at the ends of the other of said plates for clamping the ends of an abrasive sheet extending over the said cushion pad, said plates being flexible for the shoe to be self-accommodating to the contour of the surface being operated upon by the shoe, each of said clamping means comprising a still jaw secured to the plate, a live jaw, and a resilient portion connected between said jaws, a cam element located in fixed relation to one of said jaws, and a key member fulcrumed against the other of said jaws and contacting the cam for sliding over said cam when the key member is forcibly rocked to move past dead center in the nature of a toggle action so as to open the jaws and hold them locked in open condition.

7. A rubbing shoe of the character disclosed comprising spaced upper and lower resilient and flexible plates, yieldable and resilient pads between said plates, a yieldable cushion beneath said lower plate over which extends an abrasive sheet with its ends extending about and upwardly at the ends of the shoe, clamping means connected to the ends of the upper plate to clamp said ends of said abrasive sheet, said plates being flexible for the shoe to be self-accommodating to the contour of the surface being operated upon by the shoe.

8. A rubbing shoe of the character disclosed comprising spaced upper and lower resilient and flexible plates, yieldable and resilient pads between said plates, a yieldable cushion beneath said lower plate over which extends an abrasive sheet with its ends extending about and upwardly at the ends of the shoe, clamping means connected to the ends of the upper plate to clamp said ends of said abrasive sheet, said plates being flexible for the shoe to be self-accommodating to the contour of the surface being operated upon by the shoe, each of said clamping means comprising a still jaw secured to the plate, a liv jaw, and a resilient portion connected between said jaws,a cam element located in fixed relation to one of said jaws, and a key member fulcrumed against the other of said jaws and contacting the cam for sliding over said cam when the key member is forcibly rocked to move past dead center in the nature of a toggle action so as to open the jaws and hold them locked in open condition.

9. A rubbing shoe of the character disclosed comprising spaced upper and lower resilient and flexible plates, spaced and transversely extending yieldable and resilient pads between said plates, a yieldable cushion extending over the lower face of said lower plate over which an abrasive sheet extends with its ends extending about and upwardly at the ends of the shoe, clamping means connected to the ends of the upper plate to clamp said ends of said abrasive sheet, said plates being flexible for the shoe to be self-accommodating to the contour of the surface being operated upon by the shoe.

10. In a rubbing shoe of the character disclosed having a plate over which an abrasive sheet extends with the ends thereof extending about the ends of the shoe, in combination, a clamping means for the abrasive sheet secured to each end of the plate, said clamping means comprising a still jaw secured to the plate, a live jaw, and a resilient portion connected between said jaws, a cam element located in fixed relation to one of said jaws, and a key member fulcrumed against the other of said jaws and contacting the cam for sliding over said cam when the key member is forcibly rocked to move past dead center in the nature of a toggle action so as to open the jaws and hold them locked in open condition, said jaw against which said key is fulcrumed being provided with an aperture and said key member having a projection extending through said aperture to provide for pivotal connection between the key member and said latter jaw.

11. In a rubbing shoe of the character disclosed having a plate over which an abrasive sheet extends with the ends thereof extending about the ends of the shoe, in combination, a clamping means for the abrasive sheet secured to each end of the plate, said clamping means comprising a still jaw secured to the plate, a live jaw, and a resilient portion connected between said jaws, a cam element located in fixed relation to one of said jaws, and a key member fulcrumed against the other of said jaws and contacting the cam for sliding over said cam when the key member is forcibly rocked to move past dead center in the nature of a toggle action so as to open the jaws and hold them locked in open condition. y

12. In a rubbing shoe of the character disclosed having a plate over which an abrasive sheet extends with the ends thereof extending about the ends of the shoe, in combination, a clamping means for the abrasive sheet secured to each end of the plate, said clamping means comprising a still jaw secured to the plate, a live. jaw, and a resilient portion connected between said jaws, a cam element located in fixed relation to one of said jaws, and a key member fulcrumed against the other of said jaws and contacting the cam for sliding over said cam when they key member is forcibly rocked to move past dead center in the nature of a toggle action so as to open the jaws and hold them locked in open condition, said still jaw having a clamping lip and said plate having an end portion spaced from said lip to provide a crimping space therebetween, and said live jaw having a lip adapted to extend into said space to form therein a crimp in the end portion of the abrasive sheet when being clamped between said jaws.

13. In a rubbing shoe of the character disclosed having a plate over which an abrasive sheet extends with the ends thereof extending about the ends of the shoe, in combination, a clamping means for the abrasive sheet secured to each end of the plate, said clamping means comprising a still jaw secured to the'plate, a live jaw, and a resilient portion connected between said jaws, a cam element located in fixed relation to one of said jaws, a key member fulcrumed against the other of said jaws and contasting the cam for sliding over said cam when the key memberis forcibly rocked to move past dead center in the nature of a toggle action so as to open the jaws and hold them locked in open condition, said still jaw having a clamping lip and said plate having an end portion spaced from said lip to provide a crimping space there- :25

between, and said live jaw having a lip adapted to extend into said space to form therein a crimp in the end portion of the abrasive sheet when being clamped between said jaws, and an arm secured to said key for rocking said key about its fulcrum and to cause said key at its other edge to slide along said cam for opening said jaws and for holding said jaws open.

14. In a rubbing shoe of the character disclosed having a plate over which an abrasive sheet extends with the ends thereof extending about the ends of the shoe,.in combination, a clamping means for the abrasive sheet secured to each end of the plate, said clamping means comprising a still jaw secured to the plate, a live jaw, and a resilient portion connected between said jaws, a cam element located in fixed relation to one of said jaws, a key member fulcrumed against the other of said jaws and contacting the cam for sliding over said cam when the key member is forcibly rocked to move past dead center in the nature of a toggle action so as to open the jaws and hold them locked in open condition, said still jaw having a clamping lip and said plate having an end portion spaced from said lip to provide a crimping space therebetween, and said live jaw having a lip adapted to extend into said space to form therein a crimp in the end portion of the abrasive sheet when being clamped between said jaws, and an arm secured to said key for rocking said key about its fulcrum and to cause said key at its other edge to slide along said cam for opening said jaws and for holding said jaws open, said other of said jaws being provided with an aperture and said key member having a projection extending into said aperture to provide for pivotal connection between said key and said other of said jaws.

l5. Ina rubbing shoe of the character disclosed having a plate over which an abrasive sheet extends with an end portion thereof extending about the end of the shoe to a clamping means, in combination, a clamping means comprising a pair of separable jaws and a resilient portion therebetween for normally closing said jaws, a cam element located in fixed relation to one of said jaws, and a key member fulcrumed against the other of said jaws and contactingthe cam for sliding over said cam when the key member is forcibly rocked to move past dead center in the nature of a toggle action so as to open said jaws and hold them locked in open condition.

16. In a rubbing shoe having a plate over which an abrasive sheet is disposed with an end portion thereof extendin about each end of the shoe for securement, in combination, a clamping means on each end of said plate comprising a pair of jaws with resilient means normally closing said jaws for gripping one end of the sheet between them, and a key member manually adjustable to a position in which it braces the jaws open in opposition to the resilient means, together with detent means holding said key member in such bracing position.

17. In a rubbing shoe having a plate over which an abrasive sheet is disposed with an end portion thereof extending about each end of, the shoe for securement, in combination, a clamping means on each end of said plate comprising a pair of jaws with resilient means normally closing said jaws for gripping one end of the sheet between them, and manually operable locking means adjustable to lock the jaws in open position in opposition to said resilient means.

18. In a rubbing shoe having a plate over which an abrasive sheet is disposed with an end portion thereof extending about each end of the shoe for securement, in combination, a clamping means on each end of said plate comprising a fixed jaw and a movable jaw with resilient means normally urging the movable jaw into gripping relation to the fixed jaw for engaging one end of the sheet between them, a key member rockably engaged with the movable jaw at a distance back of its gripping edge and a fixed detent surface with which said key member is engageable at a position in which it braces the movable jaw open with the resilient means acting to hold the key engaged with the detent surface.

19. In a rubbing shoe having a plate over which an abrasive sheet is disposed with an end portion thereof extending about each end of the shoe for securement, in combination, a clamping means on each end of said plate comprising a fixed jaw and a movable jaw with resilient means normally urging the movable jaw into gripping relation to the fixed jaw for engaging one end of the sheet between them, a key member rockably engaged with one of said jaws at a distance back of its gripping edge and a detent surface at a distance back of the gripping edge of the other jaw formed to engage and retain said key member at a position in which it braces the jaws open, the resilient means acting to hold the key engaged with said detent surface.

GUSTAF H. EKSTROM.

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