US1374425A - Sandpaper-drum - Google Patents

Description

W. L. BROWNE.

SANDPAPER DRUM.

APPLICATION FILED OCT. 2, 1920.

' Patented Apr. 12, 1921. a? :52

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SANDPALPER-DRUM.

Specification of Letterslatent.

Patented Apr. 12, 1921.

Application filed October 2, 1920. Serial No. 414,172.

To all whom it may concern Be it known that I, WARREN L. BROWNE,

a citizen of the United States, and resident of Vallejo, county of Solano, State of California, have invented a new and useful Sandpaper-Drum, of which the following is a specification. Y

The present invention relates to improvements in sand papering machines such as are used for smoothing, polishing, shaping and grinding wood or other material, and has particular reference to certain improvements .in the rotary drums for holding and maintaining sheets of sand paper or like rections. I v means the paper will be prevented from abrasive material in proper position for use.

One of the objects of the invention is to provide a sand paper drum upon which the sheet of sand paper may be securely and evenly clamped and easily and quickly adjusted to properly conform to the drum, there being provided a novel form of adjustable clamping means for this purpose.

In sand papering machines wherein the paper is clamped upon the drum by clamping devices on the ends and elsewhere on the drtun, when the paper becomes heated by friction developed in the operation of the drum, said paper contracts and often bulges or buckles or even tears or slips out of the clamps, continued use of the drum often causes irregularity to be formed in the paper or causes it to loosen. Under these conditions the drum does-not provide for a satisfactory abrasive action and usually cannot be used until the difiiculty is remedied. This amounts to re-clampi ng'and readjusting the paper and requires the expenditure ofmuch time and labor.

With my improved drum I eliminate the hereinbefore noted objections by provision of means for exerting at all times a yielding tension pulled upon the side edges of the sheet of paper while the latter is clamped upon the drum, whereby when the paper contracts or otherwise loosens or bulges the tension means will yield and at the same time pull upon the paper in opposite di- By this yielding of the tension tearing or bulging and working loose in the clamps. The tension pulls exerted while the tension means yields will cause the paper to stretch and be smoothed out on the surface of the drum. The force of the tension ull is such that said means will yield beore the paper tears or slips in the clamps but is sufficient to stretch and smooth out the irregularities in the paper.

The invention possesses other advantages and features, some of which, with the fore going, will be set forth at len h in the following description wherein shall outline in full that form of the invention which I have selected for illustration in the drawings accompanying and forming a part of the present specification. In' said drawings I have shown one form of the construction of my invention but it is to be understood that I do not limit myself to such form, since the invention as expressed in the claims may be embodiedin a plurality of forms.

Referring to the drawings; Figure 1 is a top plan view of the invention; Fig. 2 is a sectional view taken on line 22 of Fig.

5; Fig. 3 is an inside elevation of one, of the clamping devices, showing the drum shaft in section; Fig. 4 is a sectional view taken on line 44 of Fig. 5; Fig.- 5 is an enlarged longitudinal sectional view of the invention; Fig. 6 is a sectional view taken on line 66 of. Fig. 5;. Fig. 7 is a fragmentary clamp bands.

' In the present embodiment of the inven tion there is provided a drum (1) which is hollow and fixed to a shaft (2) that extends throu h walls (3) interiorly of said drum. The rum has a spiral groove 1) therein to receive the overlapped edges of a sheet of abrasive material (5) such as sand paper.

This sheet is wrapped around the drum spi-' rally with the overlapped edges in the groove 7 so as to provide an even surface at that oint- Mounted for-longitudinal movement on,

the shaft (2) so as to be movable toward and away from. the ends of said 'drum are clamp-' ing and tension devices (6) and (7) which devices are arranged so as to clamp and-hold the sheet (5) upon the drum. These devices are urged outwardly from the ends of the drum by expansion springs (8) and (9),

- abut the walls (3) of said drum and the said devices. Thus, the devices are yieldinglyheld extended by said springs and when the sheet (5) contracts due to the heat produced by'friction when in use, said devices yield against the action of the springs and prevent thesheet from tearing or slipping in the clamps. The sheet is at all times held under tensile strain sufficient to make it com form closely to the drum.

Each of" the devices 6-7 comprises a segmental expansible clamping ring 10 surrounding an annular body member 11 which latter has a central opening 12 loosely receiving the-shaft 2. n annular clamping band 13 is mounted on the ring 10 and has inwardl extending lugs 14 thereon which lugs sli ably engage the outer edge of the ring 10 so as to facilitate the mounting and the retention of the band on said ring. The sheet 5 is to be clamped between the ring and band and one of the segments 15 of the ring has a groove 16 extending obliquely across its outer face. This groove is adapted to aline with the adjacent end of the drum groove 4 whereby the overlapped edge of the sheet provides an even surface at this'point on the ring. This provides for a tight, even clamping of the sheet.

To provide for maintaining this alinement of the grooves 4 and 16 when the devices 7 and 8 are adjusted said devices carry obliquely arranged bifurcated guide plates 17, in the bifurcations of which plates are slidably mounted pins 18. These pins are carried by the drum interiorly thereof, thus the devices are, given a twisting or spiralmovement circumferentially while being moved bodily in either direction on the shaft 2. This spiral motion tends to tighten and cause the sheet to better conform to the drum.

' The body member 11 has radial slots 19 therein opening in the inner face and 'periphery thereof. These slots slidably re- 1 ceive guide pins 20 carried by the segments 15. The slotsand ins are so shaped as to permit endwise withdrawal of the pin and prevent movementof the pins out through the open sides of the slots, there being provided angular projections 21 on the sides of the pins. These projections have screw threaded openings 22 on their inner ends and said openings receive the threaded ends 'of bolts 23 which latter project through eccentrically arranged slots 24in an operating ring 25; The ring 25 is rotatably mounted on the shaft'2 and operates against the inner face of the body member 11. A sleeve 26 is mounted on the shaft2 and has an end flange 27 which abuts the ring 25. vThe springs surround these sleeves and at their outer ends abut said flanges. A gear toothed segment 28 is fixed to the ring 25 and meshes similar pinion 31 on the inner end of a shaft .32. The shaft 32 projects through the body member 11 and on its outer end is angularly faced as at 33, for coeperation with a suitable tool, not shown, whereby the shaft 32 is rotated, the worm 29 moves the segment 28 and rotates the ring 25. When the ring 25 as shown in Fig. 3 is rotated from left to right the bolts '23 move toward the outer ends of the eccentric slots 24 and toward the periphery of said ring. This causes the pins 20 to move outwardly in the slots 19 and the ring segments 15 move correspondingly equally causing the ring 10 to expand. When the ring 10 is expanded the sheet 5 will be clamped between the ring and band 13. Reverse movement of, the operating ring 25 causes contraction of the ring 10 and v this will release the sheet 5. The outward movement of the devices 6 and 7 bodily is limited by stop collars 34, and 35 fixed by set screw 36 on the shaft 2 adjacent the end of said shaft. Interposed'between. the device 6 and the stop collar 34 is a larger collar 37 which is heldin place by set screws 38. This collar abuts the device 6 and holds the device against outward movement on the shaft 2.

To provide for stretching the abraslve sheet 5 just after it is put on the drum the device 7 is arranged so that it can be moved outwardly on the shaft 2 and away from the adjacent end of the drum. This adjustment is provided for by an annular nut 39 provided with internal screw threads 40. The nut 39 is mounted upon a flanged externally threaded sleeve 41 fixed to the shaft 2 by set screws 42 which screwsextend through the flange 43 of said sleeve for engagement with the shaft. One face of the nut bears against the body member 11 of the device 7. v

Operation The sheet 5 of abrasive material is wrapped upon the drum spirally so that the edges lie overlapped in the grooves 4 and 16 with the side edges of the sheet extending over the expansible-clamp rings 10 of the devices 6 and The bands 13 are then slipped over the sheet 5 and in place over the rings 10. The shafts 33 are turned so as to turn I a tensile strain. The other s ring 8 yields somewhat since the sheet is clamped in the device 6 and said device is ulled by the stretching of the sheet inwar y toward the adjacent end of the drum. This'places an equal strain on the sheet 5 from both sides and both devices are slightly spaced from the ends of the drum. As the sheet is stretched it is also twisted by reason of the oblique or angular guides 17 and as a result of these two actions the sheet is caused to be wrapped tightly upon the drum to conform closely thereto and provide an even effective abraslve surface entirely around said drum.

As the drum is rotated at high speed when in use, the friction created by the abrasive action causes the sheet to contract or buckle. Ordinarily where nogive is permitted the sheet will slip from the clamps or tear or otherwise become irregular in contour by bulging or buckling. When this contraction occurs the devices 6 and 7 are pulled toward the ends of the drum against the action of v the springs 8 and 9. The springs therefore yieldingly exert an equal tension strain from opposite sides of the sheet and prevent the tearing or bulging or slipping of said sheet whereby at all times the sheet is caused to conform closely to and provide an even abrasive surface upon the drum.

I claim:

1. A device of the character described comprising a drum, a sheet of abrasive material on said drum, devices at the ends of the drum within which the sheet is clamped and held on the drum, and spring means urging said devices outwardly away from the ends of the drum.,

2. A device of the character described comprising a drum, a sheet of abrasive material on said drum, devices at the ends of the drum within which the sheet is clamped and held on the drum, and spring means urging said devices outwardly away from the ends of the drum, and means for bodily moving one of the clamping devices relative to the'other.

3. A device of the character described comprising a drum, a sheet of abrasive material on said drum, devices at the ends of the drum within which the sheet is clamped and held on the drum, and spring means urging said evices outwardly away from the ends of the drum, a shaft supporting said drum, a member fixed to the shaft and limiting the outward movement of one of said devices, and a member adjustable upon the shaft and engaged with the other of said devices.

4. A device of the character described comprising a drum, a shaft supporting the drum, a sheet of abrasive material wrapped upon the drum, devices on the shaft and spaced from the end of the drum for clamping said sheet, spring means for urging said devices outwardly, and means for adjusting one of said devices longitudinally on the shaft relative to the other.

5. A device of the character described embodying in its construction, a rotary drum, a sheet of abrasive material wrappedaround the drum, an expansible ring at each end of the drum, means for expanding and contracting said rings, bands surrounding said rings, said sheet being clamped between said rings and bands and spring means yieldingly forcing said rings outwardly from the ends of the drums.

6. A device of the character described embodying in its construction, a rotary drum, a sheet of abrasive material wrapped around the drum, an expansible rin at each end of the drum, means for expan ing and contracting said rings, bands surrounding said rings, saidsheet being clamped between said rings and bands, and spring means yieldingly forcing said rings outwardly from the ends of the drums, and means for moving springs urging said devices outwardly away from the ends of the drum, a stop member fixed on said shaft and limiting outward movement of one of said devices and a stop member adjustably mounted on the shaft and en a the other device.

g-gmg WARREN L. BROWNE.

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