US2162279A - Method of and apparatus for grinding and polishing - Google Patents

Description

June 13, 1939. H. R. HERCHENRIDER 2,162;279

METHOD OF AND APPARATUS FOR GRINDING AND POLISHING Filed July 30, 1938 ATTORNEY.

Patented June 1939 PATENT OFFICE METHOD OF AND APPARATUS FOR GRIND- ING AND POLISHING Henry R. Herchenrider, Pittsburgh, Pa., assignor to Minnesota Mining & Manufacturing Company, St. Paul, Minn, a corporation of Delaware Application July so, 1938, Serial No. 222,266

4 Claims. (01. 51-139) My invention relates to grinding and polishing apparatus, and more particularly to an improved form of roll, wheel or drum, employed for bringing the abrasive into-contact with the metal sheets or other material being ground or polished.

The roll is particularly designed for use as a presser roll in that it is employed for holding or backing up an abrasive belt or strip in order to provide for pressure thereon during a grinding or polishing operation. In structures of this character, it is desirable that the surface of the presser roll be hard enough to permit of sufiiclent pressure against the abrasive-carrying belt to maintain grinding pressure that will permit continued use of the belt after the sharpest structure of the abrasive has been worn down somewhat, until a point at which substantially all of the abrasive has been consumed or used up.

If a roll is employed that is rigid across its entire diameter, it cannot yield at various surface areas thereof in such manner as to permit it to follow the contour of an uneven or non-plannlar surface being ground. Also,'there is tendency toward chattering of such hard-bodied rolls. On the other hand, if a soft-surfaced presser roll is employed, there would be a tendency for the abrasive grains to be pushed backwardly into or toward the roll, with the result that such grains are not pressed against the work with sufficient firmness.

One object of my invention is to provide a roll of such construction that the surface thereof will be of sufficient hardness to provide for such rigid pressure against the belt as to firmly maintain the abrasive grains in contact with the work, and to resist the receding or deflection of the grains under grinding pressure in a direction toward the center of the roll, and at the same time to provide a roll body of suflicient yieldability to permit localized areas of the hardened peripheral surface to recede somewhat toward the axis of the roll, under grinding pressure, so that the roll can conform to uneven or irregular areas on the surface beingground.

The invention is particularly useful in connection with the grinding and polishing of miscellaneous articles and also steel strips and sheets.

Broadly stated, the invention embodies a presser roll mounted on a shaft and having a core of soft material such as soft rubber, upon the peripheral surface of which core is mounted blocks or strips of hard material that bear against an abrasive-carrying belt. By using aroll whose body is yieldable but whose peripheral surface is composed of hard blocks, each of which may yield radially independently of the other, against the soft body or core, I avoid the objections to the use of either all-hard or all-soft rolls when employed to back up a sanding belt.

Some of the forms which my invention may take are shown in the accompanying drawing wherein Figure 1 is a longitudinal sectional View through a grinding or polishing machine; Fig. 2

is a sectional view on an enlarged scale of a portion of the structure of Fig. 1; Fig. 3 is a side view of the presser roll, partly in section; Fig. 4 is a view showing hard presser blocks of different form than those shown in Fig. 3; Fig. 5 is a view taken on the line V-V of Fig. 4; Fig. 6 shows another form of presser roll mounted in a grinding machine of a different type than that shown in Fig. 1, and Fig. 7 is an end view of the structure of Fig. 6.

Referring first to Figs. 1 to 3, the numeral I0 represents one of the side frames of a grinding or polishing machine. A series of guide and supporting rollers II and I2 are journalled in the pair of side frames II], as are also pairs of guiding or feed rolls I3 and I4, either or both of which may be driven from a suitable source of power to advance a metal sheet or strip I5 through the machine. A billy roll I6 is journalled at each end in bearing blocks H, the bearing blocks being vertically adjustable in the side frames III by means of adjusting screws I8 that have screw threaded engagement with brackets I9. Each screw I8 operates against a block 20 which serves as a seat for a spring 2| that is interposed between the spring seat and the bearing block I7, so that the pressure of the roll I6 and the resistance thereof to downward thrusts can be adjusted.

In the upper part of the framework Ill, pulleys 22 and 23 are journalled, and a sanding belt 24 passes around the pulleys. A motor 25 is provided to drive the pulley to effect movement of the abrasive belt. A presser roll 26 isjournalled in the machine and serves to hold the belt 24 in grinding engagement with the work I5.

The roll 26 comprises a shaft 21, a soft core or body portion 28' of rubber or other suitable material, and a facing of hard blocks or shoes 29 which maybe of hard rubber, cork or steel, vulcanized or cemented to the soft core 28. As shown more clearly in Fig. 3, the blocks 29 are of square or rectangular form, sufficient clearance being providedbetween the blocks to permit individual blocks to be deflected relative to the other blocks when encountering uneven areas on the work being ground. By reason of the pressure upon the abrasive'belt and to offer sumcient resistance to any tendency for the abrasive grains to recede from the work under grinding pressure. when the presser roll 23 is 'iournalled on a ilxed axis, the grinding pressure can be varied by adjusting the screws I3.

The outermost corners of the blocks 23 are slightly rounded so that the presser wheel will engage the belt 24 more smoothly and thus avoid sharp deflections of the belt along the lines where it is engaged by the blocks, and also reduce danger of cutting or tearing the belt.

Instead of forming the ,blocks 23 of a very hard material, they may be of less rigid material such as of hard rubber which is not bonehard, or hard cork which is of greater rigidity I than the rubber core. These would be useful in connection with the grinding and polishing of materials such as the softer metals wherein the harder blocks are not desired to effect proper abrading action or pressure, because the harder blocks would tend to push the abrasive too deeply into the softer metals and cause the abrasive.

grains to be torn loose, causing rapid grain loss from the abrasive belt. 7

Referring now to Figs, 4 and 5, I show a modification of the form of presser roll shown in Figs. 1 to 3, in that instead of the rectangular shaped hard blocks 23, I employ blocks 3! of diamond shape, mounted on a soft core or backing 32, wherein the leading edges of the blocks gradually enter into engagement with the belt, because of the angular lines of such edges, it being seen that the blocks will in efl'ect be brought into point contact with the belt and then be moved progressively into full-faced contact therewith. The blocks 3i also have their comers rounded as shown more clearly in Fig. 5.

In Figs. 6 and 'l I show another manner in which hard-surfaced and soft-cored rolls may be employed. In this instance a motor 33 drives a wheel 34 around which an abrasive belt 35 passes, the belt also passing around a pulley 36. The wheel 34 is provided with'a soft rubber core faced by hard'blocks 31 which correspond to the blocks 29 and 3|, but are in the form of strips which extend axially across the wheel.

fact that the blocks are of hard material, they provide sufilcient rigidity to permit of adequate This arrangement is employed for polishing small articles or narrow strips which are manually or otherwise brought into engagement with the belt :2 some point along the periphery of the wheel It will be understood that the cores of the presser rolls may be of desired degrees of softness as, for example, 20 to standard rubber hardness durometer gauge.

I claim as my invention:

1. A grinding and polishing machine comprising an abrasive belt or the like, means for moving said belt, and a presser roll for holding said belt against materials being ground or polished, during movement of the belt, the said roll having a soft core which-supports blocks of harder material disposed peripherally thereof for engagement with said belt.

2. A grinding and polishing machine comprising an abrasive belt or the like, means for moving said belt, and a presser roll for holding said belt against materials being ground or polished, during movement of the belt, the said roll having a soft core which supports blocks of harder material, each of which extends from end-toend of the roll and which are disposed peripherally thereof for engagement with the said belt.

3. A grinding and polishing machine comprising a flexible abrasive-carrying element, means for moving said element. and a presser roll for holding said element against materials being surfaced, during movement of the element, the said roll having a soft core that supports diamondshaped blocks of harder material which are arranged in rows extending axially and peripherally of the roll, the blocks of each row being in partially interspersed relation with the blocks of adjacent rows.

4. A grinding and polishing machine comprising an abrasive belt or the like, means for moving said belt, and a presser roll for holding said belt against materials being ground or polished, during movement of the belt, the said roll having a soft core which supports blocks of harder material disposed peripherally thereof for engagement with said belt, the said core being of materially greater thickness than the said blocks.

HENRY R. HERCHENRIDER.

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