US2468921A - Grinding wheel dressing mechanism - Google Patents

Description

Y May 3, 1949. s. P. BRUCE GRINDING WHEEL DRESSING MECHANISM Filed April 1, 1947 I N V EN TOR. 5 2 4/? 75411:] 2 5272166.

I Patented May 3, 1949 GRINDING WHEEL DRESSING MECHANISM- Stanford P. Bruce, Detroit, Mich., assignor to Wheel Trueing Tool Company, Detroit, Mich., a corporation of Delaware Application April 1, 1947, Serial No. 738,568

Claims. (Cl. 125-11) This invention relates broadly to new and useful improvement in tool holders and more particularly to a holder for diamond tools of the type conventionally used for dressing grinding wheels and the. like.

In order to maintain the working face of a to dress it from time to time. One way of doing this is to move a diamond point across the working face while the wheel is being rotated about its axis. Since the diamond is much harder than the grinding wheel, it cutsaway a small portion of the wheel and leaves a fresh, smooth and true working surface. 7

In practice, the diamond tool is mounted in a suitable carriagev designed to hold it steady and at a proper angle-to the wheel during the dressing operation. Heretofore, however, dimculty has been encountered in preventing chattering of the tool in the holder. Vibration or chattering results from play between the tool and the holder or between parts of the holder and leaves the surface of the grinding wheel rough and unfit for accurate work.

The problem of vibration is furthercomplicated by the fact that it usually is considered necessary or desirable to rotate the diamond tool periodically to present a fresh cutting edge to the grinding wheel and to prevent the diamond from being worn excessively on one side by the wheel. Consequently, the diamond tool or some part of the holder associated therewith must be rotatable and heretofore the parts have been associated in such manner that the working clearances necessary for rotation also permit vibration or chattering of the parts in use.

An important object of the present invention can be readily adapted to practically any type of grinding machine.

. Still another object of the invention is to provide a holder of the above-mentioned character which is simple in constructiomefficient in operation, and relatively inexpensive to manufacture.

Other objects and advantages of the invention will be apparent during the course of the following description.

In the drawings forming a part of this specigrinding wheel true and smooth. it is necessary tional view takenon the line 2-2 of Fig. 1, andflcation and wherein like numerals are employed to.designate like parts throughout the same,

Fig. 1 is a fragmentary, perspective view of a conventional grinding machine showing apparatus embodying the invention associated therewith and in operative relation to the working face of the wheel, Fig. 2 is an enlarged, vertical, transverse sec- Fig. 3 is a vertical, longitudinal, sectional view taken on the line 3-3 of Fi 2.

In the drawing, the device embodying the present invention is shown associated, by way of illustration, with a conventional grinding machine In having a rotatably driven grinding I wheel l2 and a reciprocable table it. Table H is movable back and forth in front of the grinding wheel I! .and in a direction parallel to the axis about which the wheel rotates in the usual manner. 7

According to the present invention, the grinding machine I 0 is provided with a wheel dressing mechanism, which considered in certain of its broader aspectscomprises a support is fastened to and movable with the table It, a stationary mounting 18 in the support, and a rotatable holder 20 for the conventional diamond tool 22 in the mounting. At the forward end thereof, the tool holder 20 is formed with a radial flange 24, and the mounting i8 is provided with opposed radial seats 26 and 28 disposed in confronting relation to the front and rear surfaces, respectively, of the flange 24. As best shown in Fig.

3, the spacing between seats 26 and 28 is greater than the thickness of flange 24 and an annular spring element 30 confined between seat 26 and the front radial face of flange 24 urges the flange axially rearwardly against seat 28. Spring 30 is yieldable to permit rotation of the holder 20 in mounting I8 but exerts sufficient axial thrust against the holder to prevent chattering of the same during operation of the device. Suitable means hereinafter described indetail are provided for rotating holder 20 and for indexing the. same during such rotation.

More specifically, the support is here shown by way of illustration comprises a casting having a base portion 32 arranged transversely of the table i4 and pivoted, as at 34, to hinge brackets 36 on the forward edge of the-table. At the for ward edge of base portion 32 is an integral foot 38 which seats solidly on the table It and supports the wheel dressing mechanism for proper engagement with the grinding wheel l2. The

wheel dressing mechanism is moved back and dowuwardly through the boss to the bore til is an internally threaded opening do which receives the hand screw :38. As best shown in Fig. 3,

hand screw 68 can be tightened against the mounting it to hold the latter fixedly but -re-' movably associated with the support it.

The mounting it comprises an outer generally tubular casing so, an Oilite bearing 52 in the forward portion of the casing, and a nut 55 threaded on the forward end of the casing. The nut 54 is removable to permit holder 20 to be assembled in mounting l8, and it has an inwardly extending radial flange 56 which defines the forward seat 26 and retains the spring 3G in the manner hereinabove described. As best shown in Fig. 2, bearing 52 isretained against axial movement rearwardly in the casing 50 by radial shoulders 58 and 60 in the latter. The forward end of the bearing 52 defines the rear seat 28 hereinabove referred to and, by reason of the nature of the material from which the bearing is made, the seat 28 presents an antifriction surface to flange 24$.

As suggested, the. holder 2b is rotatably received in mounting l8 and is formed with an axial socket or bore 52 which opens through the forward end thereof and snugly receives the diamond tool 22. A set screw 86' normally holds tool 22 fixedly in a selected axially adjusted position in the socket 62. At its rearward end, the holder 2% extends axially from the mounting casing Eli and the projecting portion thereof carries a hand wheel 6t which'is normally secured by a set screw 68 and provides for manual rotation of the holder.

The indexing mechanism which controls rotation of holder 20 comprises a radial bore '58 at the forward end of mounting is, which bore extends through the casing 583 and bearing 52 and registers with an annular series of circumferentially spaced sockets or serrations E2 in the outer surface of holder 29. A ball detent H at the inner end of bore ll! projects into any one of the sockets l2 disposed in register with the bore and is yieldably urged against the holder 2@ by a compression spring IS. A threaded plug 18 in the outer end of bore 8!! is adjustably axially against spring T5 to regulate the pressure which the latter exerts against ball detent It. When the holder is rotated, ball detent it rides along the surface thereof and drops successively into one socket 12 after the other. .Manifestly, when ball detent it is seated in one of the sockets i2 it maintains the holder 20 normally stationary until such time as the latter again is rotated.

In' operation, the diamond tool 22 is presented to the working face of grinding wheel-l2 in'the' conventional manner and, from time to. time, the holder 20 is turned angularly a sufllcient distance so that the ball detent i4 is pushed from one socket l2 and drops into the next adjacent socket. Preferably, the holder 20 is rotated in the same direction each time so that wear on'the diamond point is substantially uniform. Each time the holder 20' is adjusted. angularly in mounting it the diamond tool presents a new cutting edge to the grinding wheel and the wear occurs on a fresh portion of the diamond. As a result, the diamond assumes the shape of a polysided pyramid, as shown in Fig. 3, its effective life is substantially increased, and the cutting or dressing action materially enhanced.

A particular feature of the invention resides in the manner in which holder 26 is associated with the mounting is. Specifically, by providing the holder 2b with a radial flange 2 and pressing the flange yearwardly against a fixed shoulder by a relatively stiff spring 30, I am able to adjust the holder angularly or rotatably from time to time without undue binding and at the same time to eliminate destructive chattering of the parts when the device is in use. In this connection, any suitable spring or series of springs 30 may be used, but I have found that a single annular undulating strip of spring metal so constructed and arranged as to be confined and compressed between flange 26 and seat 26, when nut 54 is tightened, is best suited for this purpose.

Also, it is desirable to reduce the axial distance between the diamond point and theshoulder 28 which supports the holder 20 as much as possible in order to reduce the effect of any slight vibrating movement which may occur at the surface of the wheel during the dressing operation. I achieve this result by locating the flange 24' at the forward end of holder 20, and experience teaches that this arrangement is pre-eminently satisfactory.

It is to be understood that the-form of the invention herein shown and described isto be taken as a preferred example of the same, and that various changes in the size, shape and arrangement of parts may be resorted to without departing from the spirit of the invention or the scope of the appended claims.

Having-thus described the invention, I claim: 7 1. In a device of the character described, a mounting, a tool holder rotatable in said mounting, said tool holder having forwardly and rearwardly directed annular shoulders, said mounting having annular radial seats disposed in confronting relation to said shoulders and provided behind said seats with an elongated bearing rotatably supporting said tool holder, and spring means confined between the forwardly directed shoulder and its seat for urging the rearwardiy directed shoulder solidly againstits seat, whereby to prevent chatter of the parts during operation of the device.

2. In a device of the character described, a mounting, a tool holder rotatable in said mounting, said tool holder provided adjacent the forward end thereof with a radial flange, said mounting provided with opposed annular seats disposed in confronting relation to the opposite radial surfaces of said flange and the seat confronting the rear radial surface'of the flange having an antifriction surface, and spring means in the radial seat which'confronts therewith;

.3. I The combination asset forth in claim 2 ineluding means for manually'rotating said tool holder in said mounting, an indexing mechanism acting onsaid tool holder to yieldably' 'stop rotationthereof after a predetermined angular movement about its axis.- r

4. In a grinding wheel dressing mechanism,

a mounting having a'forwardly directed radial seat, a tool holder rotatable in said mounting, said tool holder having a radial flange thereon, and resilient means acting between said mounting and said flange to hold the rear surface of said flange against said radial seat.

5. In a grinding wheel dressing mechanism, a

mounting, a tool holder rotatable in said mount-- ing, said tool holder having a radial flange and said mounting having radial shoulders disposed in confronting relation to the front and rear surfaces of said flange, and resilient means acting between the forward surface of said flange and the radial shoulder confronting said surface to hold the rear surface of said flange against its confronting radial shoulder.

STANFORDP. BRUCE.

6 amnnoas CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS I

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