US2821974A

US2821974A - Grinding wheel dresser

Info

Publication number: US2821974A
Application number: US408652A
Authority: US
Inventors: Kish Joseph; Brancato Frank
Original assignee: Ex-Cell-O Corp
Current assignee: Ex-Cell-O Corp
Priority date: 1954-02-08
Filing date: 1954-02-08
Publication date: 1958-02-04
Anticipated expiration: 1975-02-04

Description

Feb. 4, 1958 J. KlsH ET AL GRINDING WHEEL DRESSER 2 Sheets-Sheet l Filed Feb. 8, 1954 VEN-road C-jodep H @idk Feb. 4, 1958 Filed Feb. 8, 1954 J. KlsH ET AL GRINDING WHEEL DRESSER 2 Sheets-Sheet 2 mv @ou sph. @iufm (j prami )gv-anca@ United States Patent-O 4 Claims. (Cl. 12S-11) The present invention relates to a multiple disc grindmg wheel dresser. It nds particular although not necessarlly exclusive utility in dressing a plurality of grind- 'ing wheels which have been mounted on a grinding head spaced for use with a particular workpiece.

Quite often, in the manufacture of transmission shafts and the like, it is necessary to machine a plurality of snap ring or similar grooves on predetermined centers wherein the location of the centers has a tolerance of from threeto ve-thousandths of an inch and the width of the snap ring grooves has a tolerance on the order of plus or minus ten one-thousandths of an inch. Commercial manufactuuring methods dictate the formation of such grooves by grinding as opposed to other methods of machining. This is normally accomplished by using a plurality of grinding wheels on a single grinding head. It is necessary, of course, to dress such wheels to the appropriate dimensions required by the particular job on which they are to be used. In order to insure the accuracy of the center locations and thicknesses of replacement grinding wheels which replace the worn wheels from time to time in the course of manufacture, it is desirable to refer each dressing operation to a particular standard in order to insure uniformity.

Accordingly, its is an object of the invention to provide a grinding wheel dressing arrangement capable of dressing a plurality of grinding wheels on a single grinding head to close tolerances, both as to thicknesses and as to center locations.

An associated object of the invention is to afford a grinding wheel dressing tool which is interchangeable with the workpiece to be ground, thereby achieving the advantage of dressing the grinding wheel without removing the grinding wheel head from its operating position.

An additional object of the invention has for its purpose the reducing of chatter and the consequently induced inaccuracies when thin grinding wheels are dressed at high speeds.

Further objects and advantages of the invention will become apparent as the following description proceeds, taken in connection with the accompanying drawings, in which:

Figure l is a cutaway plan View along the longitudinal axis of a grinding wheel dressing tool in operative relation with a grinding wheel head.

Fig. 2 is an enlarged partial section of the diamond type dressing tips showing their mounting within the grinding wheel dressing tool.

Fig. 3 is an enlarged plan view looking down the longitudinal axis of the grinding wheel dressing tool and showing the dressing tool support.

Fig. 4 is a schematic diagram showing the operative relationship between the diamond type dressing tool cutting edges and their associated grinding wheel to be dressed.

Although a particular embodiment of the invention has been shown and described in some detail herein, there is no intention to thereby limit the invention to such devis embedded a typical industrial diamond point 25.

u2,821,974 Patented Feb. 4, 1958 tails of the embodiment. On the contrary, the intention is to cover all modifications, alternative embodiments, usages and equivalents of the grinding wheel dressing tool falling within the spirit and scope of the invention as expressed in the appended claims.

In the present instance, the invention has been shown as Vembodied in a grinding wheel dressing unit 10 such as that shown in Fig. 1. Although this particular unit contemplates dressing three grinding wheels, it will be understood that the invention is adaptable to the dressing of any number of grinding wheels ixedly located along a common axis of rotation. The particular unit shown has been demonstrated as capable of dressingthree grinding wheels to a thickness of less than one-tenth of an inch on centers spaced less than two inches apart where the tolerances run in the order from plus or minus three to ten one-thousandths of an inch.

Because grinding wheels working to these dimensions must operate at high speeds, additional dressing operational problems are introduced. Wobble and chatter often result from uneven or too rapid a feed. The wheels may be dressed to a proper thickness, but due to the lack of skill of the operator, the center tolerances may not be met. The converse may also be the case. It is desirable to refer all of these dimensions to a xedstandard.

Such a xed standard in a mechanism for practicing the invention illustrated herein is the backbone of a dressing tool 10 in the form of an arbor 11. The axis is in operation parallel to the axis kof rotation of the grinding wheel head 12 and its associated grinding wheel discs 14. Means, not shown in the drawings here, are provided for incrementally shortening the distance between the axis of rotation of the grinding wheel head 12 and the axis of rotation of the grinding wheel dressing tool 10 while both units are rotating. Normally, the two units rotate in opposite directions as illustrated diagrammatically in Fig. 4. The grinding wheel head ro'- ice tates with a peripheral speed of approximately five to v seven thousand feet per minute, while the grinding wheel dressing tool 10 rotates at approximately 150 R. P. M.

More particularly, the two principal rotating elements involved appear in their operational relationship in Fig. 1. The grinding wheel head 12 is fxedly mounted to a drivingly rotated spindle -15 of the grinder 16. The grinding wheels `14 are replaceably mounted within the grinding wheel head 12 at centers corresponding with the centers of `the groove to be ground in the workpiece. It will be understood that the grinder 16 is positioned for advancement toward and from the workpiece while the spindle 15 rotates at high speed.

One of the objects of the invention is to dress the new .discs in the grinding wheel head without removing the `the grinder or similar machine used for rotating the workpiece. The dressing tool arbor 11 is adapted for use in association with a driving dog 20 and engaging arm 21 for drivingly rotating it in the same fashion as` the workpiece. Located along the axis of the dressing tool arbor 11 and perpendicular thereto are the dressing bit supports 22, shown here in the form of modified discs, as illustrated in detail in Fig. 3.

In greater detail, it will be seen from Fig. 3 that the dressing bit support 22 is in the form of a disc or wheei modified at diametrically opposed portions to mount the dressing bits 24. The dressing bits 24 are normally cylindrical in shape, terminating at a conical point in which The invention, naturally, is not limited to the type of dressing `3 bit point or particular configuration of the dressing bits. The form of dressing bit shown, however, serves to illustrate the type of ,dressing bit used commercially. t

For best operation, it has been found that the dressing bits 24operate in pairs, one performingA the roughing cut and kone performingy the finishing cut. The, roughing cut dressing bit 24 is normally spaced at a radius from the center of the dressing bit support 22 at a distance approximately one thirty-second of an inchl greater than that of the finishing bit. It will be appreciated, of course, that the locations of the dressing bits will vary as thel direction of rotation of the dressing tool arbor and grinding wheel are varied. In the particular instance illustrated, the grinding wheels 14 rotate counterclockwise when viewed from the tailstock and the dressing wheel arbor 11 also rotates lcounterclockwise when viewed from the same location, resulting `in the head-on meeting of the dressing wheel tool bit and the grindingwheel Vto be dressed.y

Because the grinding wheel 14, particularly in thecase of snap ring grooves `used in other applications for which the grinding wheel dressing tool of the invention finds utility, is oftentimes of thin section (i. e., less than onetenth of an inch), a considerable amount of chatter is often experienced in dressing the wheel. It has been found that the undesirable effects of chatter can be minimized by alternatively dressing the opposed faces of the grinding wheel, allowing a period of dwell during which the rotation of the wheel dampens the wobble and chatter induced during the dressing operation. Accordingly, the dressing bit support discs 22 are positioned along the arbor 11 and bored to receive the dressing points 24 in such a manner that upon rotation of the dressing tool arbor 11, the dressing bits alternatively engage the opposing faces 'of each grinding wheel 14. Naturally, a wide variety of locations and means for fixing the dressing bits 24 to their associated supports 22 may be found expedient for the particular jobs involved. lt is important, however, to locate the dressing bits in such a manner that they engage their grinding wheels 14 alternatively so that the chatter, for example, set up in the disc 14 by one pair of dressing points is dampened before the opposed pair of dressing bits'engages the opposite face of the grinding wheel.

The advantages and spirit of the invention are more readily appreciate when the step-by-step method of dressing a plurality of grinding wheels is followed. The operation of grinding wheel dressing unit 10, exemplifying the invention, will serve as an illustration. First, the rough grinding wheels 14, as received from the stock room, are removably secured in the grinding wheel-head 12. The grinding wheel head 12 is then, if removed from the grinder 16. replaced on the spindle 15 of theV grinder 16. The workpiece is removed from its location between the headstock 18 and tailstock 19 of its associatedmachine. The grinding wheel dressing tool arbor 11 Vis next substituted for the workpiece between the same head 18 and tail 19 stocks as used for the workpiece. The grinding wheel dressing unit 11 is then rotated at slow speed and the grinding wheel head 12 is rotated at its normal operating speed. The grinder 16 is then advanced toward the dressing unit 10 at a linear speed commensuratewith the depth and number of cuts to be made by the various dressing bits 24. After the grinding wheels 14 are dressed to`size, the grinder 16 is then withdrawn from the dressing unit replaced by the workpiece.

Because the grinding wheel dressing unit can be set and adjusted in thetool room to dress all of the grinding .wheels 14 simultaneously, and repeatedly, a fixed Vstandard Abased upon the exact working dimensions of the Vdressing,toofunit therebyreplaces a multitude ofskilled "dressing operations required by the machine operator when each grinding surface must be dressed individually prior to use.

We claim as our invention:

1. A dressing tool for dressing the sides of thin rotary grinding wheels comprising a rotatable disk and a single pair of diamonds mounted on one side of the disk near its periphery, one of said diamonds being slightly spaced angularly and radially outwardly from the second diamond to define a roughing point and the second diamond extending slightly further from the face of the disk than the first diamond to define a finishing point.

2. A dressing tool for dressing the facing sides of a pair of thin spaced rotary grinding wheels comprising a rotatable disk having a single pair of diamonds mounted on one side face of the disk near the periphery thereof and a second single pair of diamonds mounted on the other side of the disk near the periphery thereof and .dlametrically opposite the first pair, one diamond `of each pair being slightly spaced angularly and radially outwardly, from the other diamond of each pair to define a roughing point and the other diamond of each pair. extending slightly further from the face of the disk to define a finishing point.

3. -In a precision grinding machine having a thin grinding wheel mounted on a rotary shaft for cutting workpiece grooves, means for dressing the grinding wheel sides comprising a disk mounted for rotation on a shaft parallel to the grinding wheel shaft in a given direction, means for laterally moving the dressing disk shaft relative to the grinding. wheel shaft to advance the disk periphery along successive` radial portions of the grinding wheel side face, and a single pair of diamonds mounted on one side of the disk near the periphery thereof, the first diamond being slightly angularly advanced with respect to the second diamond in said given direction of rotation to define a roughing point, and the second diamond being slightly spaced radially inward with respect to the first diamond and extending further laterally from the disk side to define a finishing point.

4. In a precision grinding machine having a pair of thin rotary grinding wheels mounted on a rotary shaft for-cutting grooves in rotatably mounted workpieces, means for dressing the facing sides of the grinding wheels comprising a disk mounted for rotation on a shaft parallel to the grinding wheel shaft in a given direction, means forilaterally moving the dressing disk shaft relative to thc grinding wheel shaft to advance the disk periphery along successive radial portions of the facing grinding wheel sides,,a first single pair of diamonds mounted on one side of the disk -near the periphery thereof, a second singlepair ofdiamonds mounted on the other side of the disk near the periphery thereof and diametrically opposite thefirst pair, the first diamond of each pair being slightly angularly advanced with respect to the second diamondin -said given direction of rotation to define a roughingpoint, and the second diamond of each pair ,beingslightly spaced radially inward with respect to the first diamond and extending further laterally from the disk side to define a finishing point.

lReferences Cited in the file of this patent UNITED STATES PATENTS 47,255 Drake Apr. 11, 1865 161,835 Squire Apr. 16, 1875 298,353 Crump May 13, 1884 438,035 Turner Oct. 7, 1890 1,902,555 Hughes Mar. 2l, 1933 1,919,288 Bath July 25, 1933 2,073,678 .Broughton Mar. 16, 1937 2,322,579 Kutscha June 22, 1943 2,345,050 .Jansen Mar. 28, 1944 2,347,283 Ross Apr. 25, 1944 Y2,348,089 Niekirk May 2, 1944 2,659,357 Osplack Nov. 17, 1953