US2019889A

US2019889A - Polishing machine

Info

Publication number: US2019889A
Application number: US735244A
Authority: US
Inventors: Alfred V Breed
Original assignee: CURTIS MACHINE CORP
Current assignee: CURTIS MACHINE Corp
Priority date: 1934-07-14
Filing date: 1934-07-14
Publication date: 1935-11-05
Anticipated expiration: 1952-11-05

Description

NW5, 1935. v BREED 2,019,889

POLISHING MACHINE Filed Ju ly 14, 1934 3 Sheets-Sheet 1 lllllllllllllluufllllllllllllllllllllflllllllllllllllllk fil red (d Brad 5 Iii: 6mm

Nov. 5, W35.

A. v. BREED I POLISHING MACHINE Filed July 14, 1954 5 Sheets-Sheet 3 Patented Nov. 5, 1935 UNITED STATES PATENT OFFICE POLISHING MACHINE Application July 14, 1934, Serial No. 735,244

15 Claims.

This invention relates to an improvement in polishing machines and more particularly to machines of the type having an abrasive belt serving as the polishing medium.

The invention is primarily directed to a machine for polishing sheet or flat material through the use of a continuously moving abrasive or polishing belt in conjunction with adjustable and relievable pressure means which holds the belt in contact with the material. Prior to this invention, many kinds of machines have been developed for use in polishing flat material, In some instances a narrow abrasive belt was provided and the material, to be polished, moved back and forth in a plane perpendicular to the direction of travel of the belt. Such a machine, applied to polishing sheet steel, while removing the rough blemishes from the steel as it came from the rolling mill, could not produce the scratch free surface desired. Another type of machine in use utilized a wide belt and required apower driven roller to be moved into contact with the steel to be polished. This roller was not only unwieldy but entirely incapable of following any uneven surfaces of the sheet of steel and in consequence it was necessary to grind off the high spots before the low spots could be reached by the belt to be polished. By reason of the belts used in these machines as well as the lack of flexibility of the machine itself, great difiiculty was encountered in preventing some of the abrasive material from becoming ground into the surface of the steel by the moving belt and thus producing scratches which could not readily be removed. The belts for these machines were necessarily constructed of canvas or other heavy fabric coated with a suitable abrasive and were extremely costly.

When the abrasive surface of a belt of this type.

became worn, it was either necessary to purchase a new belt or the user was required to recoat the old belt. This latter procedure, although less costly, was unsatisfactory since it was impossible to provide a uniform abrasive coating on the belt in a manner employed by the belt manufacturer.

The present invention has been designed to produce a satisfactory polish on sheet steel, thus overcoming the above mentioned difiiculties and has for its principal objects first, to provide an abrasive belt of sumcient width to simultaneously polish the full width of a given sheetof steel; secondly, to provide a pair of power driven rollers on which the abrasive belt is carried; third, to

provide a belt pressure roller, generally midway between the power driven roller WhiQh 15116.1,-

tically adjustable to produce a variable pressure contact of the belt with the steel; fourth, to support this roller in such a manner that it may pivot longitudinally about a transverse axis and may have a slight upward yield under spring tension when an unusually high spot on some part of the steel is contacted or when the carriage on which the steel is supported has reached the end of its travel in one direction and is being reversed; fifth, the provision of a further roller substantially midway of the power driven rollers and above the pressure roller which is movable to increase or decrease the tension of the belt as well as to cause said belt to properly track upon the power driven rollers; and sixth, the provision of power driven rollers, the support for which being such that, upon release of the tensioning roller, a worn belt may bequickly removedand replaced without altering or disassembling any part of the machine. Other objects and advantages of the invention will be more fully understood from a consideration of the following specification taken in conjunction with the accompanying drawings and in which,

Figure 1 is a side elevation of a machine embodying one form of this invention;

Figure 2 is a plan view of the structure shown in Figure 1;

Figure 3 is an enlarged view of the pressure and tension rollers taken substantially on the line 33 of Figure l;

Figure 4 is an enlarged vertical sectional view taken substantially on the line 44 of Figure 3 and shows yieldable supporting means and a quick release operator for the pressure roller;

Figure 5 is a fragmentary view similar to Figure 4 showing the method of displacing the pressure roller and abrasive belt from contact with Y the work at the end of the travel in one direction of the work supporting carriage; Figure 6 is a fragmentary vertical sectional view of the bearing support for the pressure roller;

Figure 7 is a fragmentary sectional view of the pivotal support of the quick release lever; Figure 8 shows means for locking the release lever to retain the pressure roller in elevated position;

Figure 9 is an enlargedfragmentary view partly in section showing the method of adjustment of the tensioning roller by which to cause the belt to track on the power driven rollers; and

Figure 10 is a fragmentary view of one of the power driven rollers, being taken substantially 0. 1 the line l0l0 of Figure 2. V

Reference is now had generally to Figure 1 of the drawings which discloses a machine bed on which is mounted a longitudinally movable carriage. A sheet of steel is secured in any suitable manner to this carriage. Above the carriage a vertically adjustable frame is located on which are supported parallel rollers arranged on axes at right angles to the length of the bed. A suitable power unit is connected with one of the rollers which in turn is connected with the other roller in order that both of said rollers will have synchronous power drive. Somewhat below and between the driven rollers is a pressure roller which is mounted in a horizontal guide to facilitate removal at one side of the machine and replacement by a new roller or bufling roller. This roller is so mounted that it is vertically adjustable toward or away from the carriage and is so connected to its support that it may pivot longitudinally about an axis perpendicular to its axis of rotation. The support for this roller is also provided with spring means which permits a slight upward yield of the roller during certain con itions of use. A tensioning roller, preferably directly above the pressure roller, is mounted on a vertically adjustable support and is also capable of longitudinal pivoting about a transverse axis. The frame on which all of the rollers are supported is designed to permit mounting a belt upon the rollers without disassembling any of the rollers or any other part of the machine. When the belt is so mounted, the tensioning roller is adjusted to take up the slack of the belt and the pressure roller adjusted to cause the belt to contact with the steel to be polished. By reason of the use of a pair of driven rollers and a pressure roller therebetween, an inexpensive paper abrasive belt is entirely satisfactory and since these belts are readily removable and replaceable, the possible more frequent replacement thereof constitutes no loss of time in use of the machine as compared with other machines requiring partial disassembly to remove and replace the belt.

The reference numeral I0 is employed to designate a polishing machine embodying one form of the invention. The machine includes a bed ll suitably elevated from the floor on posts l2. Formed in the bed is a track upon which is located a longitudinally movable carriage I4. The support for and mechanism by which the carriage l 4 is reciprocated is conventional and therefore forms no part of the invention. Projecting upwardly from adjacent one side of" the bed is a supporting frame I 5. This frame has a vertical face formed with guides l6. Against this face and interfitting with the guide I6 is a roller supporting frame I! which projects from the member l5 horizontally over the central portion of the bed I I. The frame I! includes a central portion It to opposite sides of which are secured roller supporting yokes 20 and 2| by means of bolts 22. The yoke 20 has a central portion 24 which terminates in spaced arms 25. Suitable bearings are provided in the ends of the arms to support the shaft 26 of one of the belt driving rollers 21. It will be noted that the shaft 26 projects through and beyond both arms 25, having a gear or sprocket 29 keyed to one end and a pair of V-pulleys 30 keyed to the other. The gear 29 is connected in any suitable manner as by a chain 32 with a power source in the form of an electric motor 33 which may be supported on a separate base or an offset arm joined to the base II. The yoke 2| is also provided with suitable bearings to support a roller 35 on a shaft 36. One end of the shaft 36 projects through and beyond the yoke and is fitted with a pair of V-pulleys 31. The pulleys 30 and 31 of the

rollers

21 and 35 are connected by two V-belts 38. Thus power transmitted from the motor 33 to the roller 21 is also conveyed o the roller 35 providing the machine with a pair of synchronous belt-carrying driven rollers.

Mounted on the central portion l8 of the frame i? is a fixture 46 which is formed with a guide block 4 I. The block 45 is engaged by a further block 42 to which is attached the support for a belt tensioning roller 44. The support includes a. yoke 45, the arms 46 of which are provided with bearings in which to receive the ends of the shaft 48 on which the roller 44 is mounted. Centrally of the yoke 45 there is a depending bracket 59 through which an opening is made to receive a bolt 5i. block 42 and serves to support the yoke 45 for pivotal movement. The bracket 53 is continued in an arm 53 which projects downwardly and terminates in an enlarged portion 54 provided with an opening 55 thcrethrough. Mounted in the opening 55 is a short shaft 51 which is provided with an opening 58 perpendicular to the shaft axis. The opening 58 in the shaft registers with concentric and enlarged openings 59 in the portion 54. Secured to or forming a part of the block 42 is a bracket 65 having an opening 62 therethrough. A shaft 63 projects through the opening 62 and is fitted with a collar 6 adjacent the bracket 6!. Beyond the collar 84 the shaft 331s threaded and projects through one opening 59 to have threaded engagement with the walls of the opening 58 in the shaft 51. The shaft 63 continues outwardly of the portion 54 through the second opening 59. The enlarged portion 66 of a shaft 61 is secured to the end of the shaft 63 opposite the collar 64. Shaft 63 terminates in a wheel or knob 68. As heretofore mentioned, the roller 44 serves not only to increase or decrease the tension of an abrading belt which passes over the driven

rollers

21 and 35 but also is adapted to align the belt causing it to properly track upon these rollers. Thus the roller 44 must be tiltable about an axis perpendicular to its axis of rotation. In Figure 3 of the drawings the extreme positions of tilt of the roller 44 are shown. This tilting is accomplished by rotating the knob as which causes the shaft 51 to be moved lengthwise of the threaded shaft $3, thus swinging the arm about the bolt 5i and tilting the roller supporting yoke 45.

Projecting upwardly into a threaded opening in the block 42 is a shaft '59. This shaft continues downwardly through a fixed frame H and terminates in a beveled gear 13. Mounted on the portion I8 is a pair of brackets "i4 and 15 in which is supported a shaft '55. One end of the shaft 76, projecting beyond bracket is fitted with a beveled gear T. which meshes with the gear 13. The other end of the shaft i5 is provided with a wheel E9 on which is located a knob 36. As heretofore mentioned, the entire mounting for the roller 44, which includes yoke 45 and block 42, is vertically adjustable of the guide block 4i. Rotation of the wheel 15 causes beveled gears '1? and if; to rotate, thus rotating shaft 10 which, by reason of its threaded engagement with the block 42, moves said block upwardly or'downwardly of the guide block 4|.

Beneath the frame if and substantially cen- The bolt 5! projects into the -i trally between rollers 2'! and 35 is a pressure roll- 75 er 86 which is mounted on a shaft 81. This shaft is formed with end recesses 88 to receive combined thrust and supporting bearings 89. These bearings are preferably enclosed in the recess by caps 90. An opening in each ca'p permits entrance of the supporting shaft 92 into the bear ing 89. Externally of the roller shaft 81, the shaft 92 is formed with an enlargedthreaded portion 93 which engages the threads of an opening 94 formed in the arm 85 of a yoke 96. The threads of the portion 93 are cut away to provide a smooth surface 98 for contact with a set screw'99 mounted in the arm 95. The structure above described. is adjustable to properly support the roller 86. Withdrawal of the set screw 99 and rotation of the shaft 92 projects the enlarged portion 93 thereof inwardly or outwardly of the arm 95 of the yoke 96 to give proper rotating freedom to the shaft 81. The portion 93 projects beyond the outer face of the arm 95 and is formed with a threaded opening IOI, into the walls of which a plurality of slots I02 are cut. The outer surface of this end of the portion 93 is of reduced size and receives an anti-friction bearing I93. This bearing is secured to the portion 93 by threading a stud I04 into the opening IOI causing the walls adjacent the slots I62 to be expanded into contact with the inner race of the bearing I03. A wheel I06 is mounted on the bearing I03 and serves with a corresponding wheel at the other end of the yoke 95 to elevate the roller 86 under conditions and for a purpose hereinafter set forth.

' Secured to the underface of the central portion I8 of the frame I1 in any suitable manner as by studs I09 is a bracket I I0. The bracket is formed with a pair of transverse openings III which are spaced by a central web I I2. Formed centrally of the web I I2 is an opening I I3'which is concentric with an opening II I formed in the portion I8. A further opening I I6 is made in the web II2 which connects the openings III of the bracket. This opening is in the form of a slot and receives a pinion gear III. A worm gear I I8 mounted on a shaft IIQ projects into one of the openings III of the bracket I10 to engage the teeth of the gear I I1. The shaft H9, exteriorly of the bracket H0, is sup-ported in journals I2I which are connected and supported by the bracket II 0 through arms I22 secured by studs I23. Adjacent the clear side of the portion I8 of the frame I1 is a downwardly directed flange I25 to which may be secured a plate I26. The shaft I I9 projects through the plate I26 and is fitted with a wheel I21 having a knob I28.

The gear I I1 has a centrally located threaded opening I30. Projecting through the opening I30 is a shaft I3I. This shaft is threaded throughout its length and engages the threads of the opening I30. An opening I33 is made longitudinally of the shaft. The lower end of this opening is enlarged to form a pocket I34. Projecting through the opening I33 in the shaft I3I is a rod I35. The lower end of this rod is formed or fitted with a collar I36 provided with flanges to form an annular recess I31 about the rod I35. At the meeting of pocket I34 with opening I30, a shoulder I38 is formed and'between this shoulder and the base wall of the recess I31, a spring I40 is located. This spring is of the compression type and encircles the rod I35, serving to urge the rod downwardly of the shaft I3I.

In order that the rod may not be moved out of the opening of this shaft, the upper end is formed with a threaded portion I4I with which is en- 'upper end of the shaft I3I.

gaged a collar I42 that normally rests upon the The portion I4I has threaded connection with an extension I44 for the rod I35. The upper end of this extension is formed with a slot I45 to which is joined, by means of a pivot pin I41, a lever I48. This lever is of a length to extend to one side of the machine, being terminated in a convenient handle I49. On the portion I8 (see Figures 4, 5 and 7) is a support I5! for the lever I48 which includes an upwardly opening slot I52 for receiving the lever. A suitable pin I53 serves to pivotally connect the lever with the support. The lower end of the support is formed with an annular opening I55 into which projects the enlarged threaded end I55 of a shaft I51. A collar I58 has threaded engagement with the end I56 of the shaft, being rotatable to move the support I5I upwardly 01' the shaft or to permit it to move downwardly thereon. The lower end of the shaft I51 is threaded into the portion I8 of the frame I1. As will more fully be understood from a further description of the invention, the lever 148 is for the purpose of raising the rod I 35 upwardly of the shaft I3I against tension of the spring I40. To increase or decrease the extent of upward shifting of the rod I35 by means of the lever I48, the collar I58 is rotated upwardly or downwardly to change the elevation of the lever support-I5I.

The lower'end of rod I35 terminates in a portion I60 having a transverse opening I6l therethrcughf A frame I63, having an upstanding pivot portion I64, receives the portion I60, being pivotally engaged therewith by means of a bolt I which projects through suitable openings I66 in the support I64 and the opening ml in the portion I50. The frame I63 comprises a body portion from which depend parallel flanges I61. These flanges are undercut to provide a guideway I68. The yoke 96 which supports the pressure roller 85 is provided with an overcut, along the base wall thereof. to permit being inserted into the guideway I66. When the yoke 86 is thus mounted in the frame I63, one or more set screws I10 mounted in said frame are rotated to lock the yoke in place. It will be understood that the pivotal support for the frame I63 and yoke 86 is such that the roller may move endwise about a transverse pivot in the form of bolt I65 for the purpose of following any uneven contour of a sheet of steel to be polished.

The movable carriage I 4, on which a sheet of steel is secured in. any suitable manner, is formed with side members I1 I in the outer vertical faces of each of which a longitudinal recess or groove I12 is made. Across the face of the groove I12 are plates I13 which provide a restricted opening I14 into said groove I12. A pair of trip members I15, having inclined surfaces I1 3, are located adjacent the side members I1 I, being fixed to plates I11. Each plate is formed with a slot I18 through which a bolt I19 projects. The head I of the bolt is located in the groove I12 seating against the inner faces of plates I13. jects through the restricted opening I14 and is fitted with a nut I8I. The plate I16 is vertically adjustable of a bracket I82 by means of a threaded shaft I83 which, when rotated by the knob I85, projects the plate I15 and trip members I15 upwardly. When the desired adjustmentof the height of the trip has been obtained, the nut I8I is rotated to lock the entire structure in place. Inasmuch as the groove I12 extends the full The bolt we pro- 6 length of the carriage, the trip members I13 may be adjusted to any desired location.

An abrading belt I 85 is mounted on the

rollers

21 and 35. Between these rollers the belt is supported above and beneath by the tension roller 44 and pressure roller 86. It is apparent that when the belt is properly tensioned by vertical adjustment of roller 44, roller 86 serves to engage the belt with the sheet of steel to be polished. When a sheet of steel or other material is fastened in any suitable manner to the carriage I4, polishing may commence. The trip members I I5 are adjusted lengthwise of the bed to positions adjaoent the ends of the sheet. When the carriage I4 travels toward its limits of movement in one direction, the members I are moved toward the roller 86 and wheel I86. At precisely the end of travel of the carriage in one direction, members I15 are projected under the wheels IIJ6 causing said wheels to ride up on to said members thus raising the roller 86 and releasing the pressure of the belt I85 upon the sheet of steel. It will be understood that the upward movement of the roller 88 is under tension of the spring I46 and that when the carriage moves in the opposite direction, the members I15 are withdrawn from beneath the wheels I88 thus allowing the roller 86 to again press the belt into contact with the sheet to be polished. Although there is only a short period of time when the carriage is not moving at the end of its travel in one direction or another, pressure contact of the belt during this short period will tend to burn the material adjacent the end. To eliminate this objection as well as to prevent additional wearon the belt, the trip members are provided.

It will be understood that the tension roller 44 serves to increase or decrease tension of the belt I85 as well as to cause it to track upon

rollers

21 and 35, the former being accomplished by rotation of wheel 19 and the latter by rotation of the wheel or knob 68. The pressure roller 88 is also vertically adjustable through rotation of the wheel- I21. This vertical adjustment in no way alters the tension of the spring I40 since said spring and its support are a part of the unit which is vertically adjustable. During the proc ess of polishing sheet steel, it frequently occurs that particles of abrasive from the belt or other foreign matter drop onto the sheet. Should the belt come in contact with these particles it would produce scratches in the surface of the sheet which could not be readily removed. A means therefore is provided by which to relieve the pressure contact of roller 86 upon the belt in the quickest manner and without stopping the machine. This has been accomplished through the provision of the lever I48 which, being available at one side of the machine, may be depressed to raise the roller 88 against the tension of spring I48, permitting the sheet of steel with the foreign matter thereon to travel harmlessly past. To withhold pressure contact of the belt I85 through roller 86 without altering the pressure adjustment by rotation of wheel I21, means in the form of a latch I86 is provided to secure the lever I48 in depressed position. This latch includes a swivel base I81 secured to the portion I8 of the frame IT. A rod I88 projects upwardly from the base I81 to support the latch which is adjustable vertically thereof by rotation of nuts I89.

It is contemplated that when a higher polish than that obtainable with an abrading belt is desired, the belt may be removed, roller 86 removed, and a bufling roller substituted therefor.

The bufling roller is in a yoke similar to the yoke 86 which supports roller 86 and may be rotated by a direct drive motor which would be located approximately where the wheel I86 is now located or a V-pulley which would be driven by a belt connected with one of the

rollers

21 or 35.

Although applicant has shown and described only one modification of means for supporting and controlling a fully flexible roller by which to cause an abrading belt to contact with the surface of a sheet of material to be polished, means for releasing the tension of this roller, and other structural advantages shown and described, it will be understood that modifications or other adaptations of these structures is contemplated in so far as such modifications may lie within the spirit and scope of the invention as set forth in the hereunto annexed claims.

Having thus set forth my invention what I claim as new and for which I desire protection by Letters Patent is:-

1. In a machine for polishing fiat material, a polishing belt, a roller in contact with said belt, means mounting said roller for free and unrestrained movement about an axis perpendicular to its axis of rotation, means supporting said mounting means, said latter means being adapted to adjust said roller to contact said belt with the material to be polished, and further means for releasing said roller from operative adjustment independently of said supporting means.

2. In a machine for polishing fiat material, a pressure roller, means including resilient support for said roller, said means being adapted to adjust said roller toward or away from said material, and means for releasing said roller from operative adjustment, said latter means being operable independently of the means supporting said roller.

3. In a machine for polishing flat material, a

polishing belt, a pressure roller in contact with said belt, means sustaining said roller for movement about an axis perpendicular to its axis of rotation, further means supporting said roller through said sustaining means, said further means being movable to adjust said roller to contact said belt with the material to be polished, and means operable independently of said further means for releasing said roller and said belt from operative adjustment with respect to said material.

4. In a machine for polishing fiat material, a polishing belt, a roller in contact with said belt, a yoke supporting said roller, a frame, slidably interfitting parts on said yoke and said frame, said parts facilitating removal and replacement of said roller, means sustaining said frame for movement about an axis perpendicular to the axis of rotation of said roller, and further means mounting said sustaining means on said machine.

5. In a machine for polishing flat material, a polishing belt, a roller in contact with and adapted to advance said belt to engage said material,

a supporting member on said machine having an opening, a shaft in said opening, means in said member supporting said shaft, said means being manually operable to move said shaft in said opening, a rod projecting through an opening in said shaft, yieldable means connecting said rod with said shaft, a frame sustaining said roller, said frame being joined to said rod whereby manual operation of said means advances said roller.

6. In a machine for polishing fiat material, a polishing belt, a roller in contact with said belt,

a supporting member on said machine having an opening, a shaft in said opening, means in said member supporting said shaft, said means being operable to move said shaft longitudinally of said opening, further means having yieldable connection with said shaft, a frame sustaining said roller, said frame being pivotally joined to said further means, said first means being adapted to move said roller and contact said belt with the material to be polished, and said further means being operable independently of the shaft operating means whereby to release said roller and said belt from operative adjustment with respect to said material.

7. In a machine for polishing fiat material, a polishing belt, a roller in contact with said belt, a supporting member on said machine having an opening, a shaft in said opening, a gear in said member having threaded engagement with and supporting said shaft, manually operable means for rotating said gear and advancing said shaft upwardly or downwardly of said opening, a rod projecting through an opening in said shaft, means for preventing relative movement of said rod and said shaft in one direction, and spring means permitting relative movement of said shaft and said rod in the other direction, a frame sustaining said roller, said frame being pivotally joined to said rod whereby, upon manipulation of said manually operable means, said roller may be yieldingly advanced to contact said belt with the material to be polished.

8. In a machine for polishing flat material having a continuous polishing belt, a roller in contact with said belt, a separable yoke and frame sustaining said roller, a rod in said machine, pivotal means connecting one end of said rod with said frame to permit movement of said 'roller about an axis perpendicular to its axis of rotation, a supporting member on said machine having a vertically movable shaft, said shaft having an opening through which said rod projects,

and yieldable means connecting said rod with said shaft whereby movement of said shaft in one direction relative to said supporting member causes said roller to yieldingly contact said belt with the material to be polished.

9. In a machine for polishing fiat material having a continuous polishing belt, a roller in contact with said belt, a supporting member on said machine having an opening, a shaft in said opening, means in said member supporting said shaft, said means being operable to move said shaft longitudinally of said opening, a rod projecting through an opening in said shaft, a separable yoke and frame sustaining said roller, said frame being pivotally connected with said rod, means causing said rod to move with said shaft in one direction, further means causing said rod to yieldingly move with said shaft in the opposite direction, a lever on said machine connected with said rod, said lever being operable to 'move said rod relative to said shaft whereby to release said roller and said belt from polishing position with respect to said material.

10. In a machine for polishing fiat material having a polishing belt, a reciprocable carriage supporting the material to be polished, a roller in contact with said belt, means sustaining said roller, a supporting member on said machine, yieldable means in said supporting member for advancing said roller to contact said belt with the material on said carriage, adjustable trips mounted on said carriage adjacent the ends of said material, said trips being engageable with means on the roller supporting yoke, when said carriage has completed its travel in one direction, to raise said roller and said belt from off said material.

11. In a machine for polishing flat material having a polishing belt, a roller in contact with said belt, means sustaining said roller, further means on said machine supporting said sustaining means, both of said means having yieldable connection to permit upward movement of said roller and said roller sustaining means relative to said further means, a reciprocable carriage on said machine, automatically operable trip means on said carriage and said roller sustaining means for raising said roller and said belt from polishing position when the direction of movement of said carriage is being reversed.

12. In a polishing machine having a material receiving carriage, a horizontally disposed frame overlying said carriage, a. pair of rollers, opposed yokes on said frame supporting said rollers, said rollers projecting laterally beyond said yokes and above and beneath said frame and said yokes, means for rotating one of said rollers, and further means connecting said rollers for synchronous rotation, said frame, yokes and roller rotating means being located within the space defined by a belt mounted on said rollers.

13. In a machine for polishing flat material having a polishing belt, an adjustably mounted roller in contact with said belt; said roller being movable to advance said belt into polishing position, a reciprocable work supporting carriage on said machine, means on said carriage operable to raise said roller and relieve said belt from polishing position when the direction of movement of said carriage is being reversed.

14. In a machine for polishing flat material having a polishing belt, an adjustable roller in contact with said belt, said roller being movable to advance said belt into polishing position, a reciprocable carriage on said machine, automatically operable trip means on said carriage and said roller for raising said roller and relieving said belt from polishing position when the direction of movement of said carriage is being reversed.

15. In a machine for polishing fiat material having a polishing belt, a roller in contact with said belt, means sustaining said roller, wheels mounted on said sustaining means, a reciprocable work receiving carriage on said machine, trip members on said carriage, said wheels being in the path of said trip members and movable thereover to raise said roller and relieve said belt from polishing position when the direction of movement of said carriage is being reversed.

ALFRED V. BREED.