US1984936A - Grinding wheel - Google Patents

Description

T. LARSSON GRINDING WHEEL Dec. 18, 1934.

Filed Dec. 1, 1952 ro w www M w R A m L b M 4 f W 2 D .T n. 2 w Q G ,m 3 m 7.. .6 a 4 v Z W ,0f M W Zw Patented Dee. 18, 1934 GRINDING WHEEL Thure Larsson, Worcester, Mass., assignor to Norton Company, Worcester, Mass., a corporation of Massachusetts Application December 1, 1932, serial No. 645,252

13 Claims.

This invention relates to a grinding wheel, and more particularly to a multiple unit grinding wheel composed of several abrasive units or wheels which may be angularly and individually positienes with relation to e driving shaft. It relates especially to grinding wheels of non-circular contour or wheels having specially localized structures which are adapted for grinding specially shaped work pieces.

As-disclosed in the co-pending application of Stubbs, Serial No. 612,232, it has been proposed to employ a specially shaped grinding wheel to determine the shape of the finished work piece, which may be a cam or a splined shaft. In such a machine, the preshaped grinding wheel and the work are rotated in a definite cyclic timed relation so that while the wheel contacts with the work, certain portions of the wheel periphery will always engage certain portions of the work and the rotation of both the wheel and work shall' always remain in a predetermined angular relation, thereby causing the specially shaped wheel to form a specially shaped work piece which is the conjugate form thereof. 'I'he term conjugate, as appledto the shape of the wheel, refers to that curved wheel shape which will remain in rotative contact with the surface of awork piece which is of such shape or is so mounted that the line of grinding contact varies in its distance from the axis of rotation of the grinding wheel, while the wheel axis and the work axis are maintained relatively stationary, except for feeding the wheel into the work, and provided the wheel and the work are rotated with their angular velocities equalor in a simple ratio, the grinding operation being caused by the unequal lengths of wheel and work surfaces which are moved relative to each other as they are rotated in angular synchronism.

It has been further contemplated to employ several specially shaped grinding wheels mounted to act as a multiple unit for simultaneous grinding and to have the wheels engage several stations or surfaces on the work at the same time, thus providing a means whereby all of the cams on an automotive camshaft or the pins on a crankshaft or other work pieces may be simultaneously finished. The contours of the cams on such a camshaft are usually identical, but their angular displacements relative to their supporting shaft are different; hence, the angular relations of similar portions of the grinding wheels of a mul, tiple unit must be different relative to the wheel mount and must have corresponding relations` thereto as that of the cams to its shaft. In other words, if a conjugate grinding wheel is rotated once for each rotation of its product cam, the low point of the wheel periphery and the high point of the cam must have the same angular relation to corresponding points on the wheel shaft and camshaft, since the low portion of the wheel serves to shape th high portionof the product cam during the grinding operation. It will be o appreciated, due to the fact that the periphery of the grinding wheel is much greater than that of the product cam, that a considerable portion of the grinding wheel may engage a single point on the work and thereby cause a grinding operation.

Heretofore, the 'usual type of wheel mounting, wherein a grinding wheel is firmly clamped between and rotated by a pair of clamping anges, has provided no adequate means for locating and 0 mounting a given portion of a wheel in a predetermined angular relation to its support, since there was no necessity for thus angularly locating a circular grinding wheel, due to the fact that all parts of the grinding wheel contacting with the work had the same structure throughout and performed a duplicate grinding operation. With the advent of a specially shaped or constructed grinding wheel having a distinctive grinding sector, such as one in which a sector has a structure varying in grade, shape, or in other characteristics' from the rest of the wheel, it has been found necessary to devise ameans whereby such a wheel could be angularly positioned with a denite angular relation to its support so that the Iwheel could be mounted in accurate phase relation to the work.

For example, in the case of a conjugate grinding operation wherein the wheel and work are rotated in a denite phase relation and the shape 40 of the wheel determines the shape of the work, it is essential that a means be provided whereby the grinding wheel may first be mounted on its support vin a correct angular relation therewith, so that a desired low or high sector of the wheel may be angularly located to engage a desired high or low portion of the work during the grinding operation. If the grinding wheel were not mounted in accurate angular relation, itay distinctive grinding sector would incorrectly engage the work when the wheel was brought into contact therewith and cause damage to the work, uneven wheel wear and probable wheel breakage, thereby endangering the safety of the machiney operator.

It is, therefore, the primary object of this invention to provide a means whereby a grinding wheel may be mounted on a support with a given point or portion of the wheel having a denite angular relation to a given point on its support.

A further object of this invention is to provide a wheel construction and a wheel mount therefor whereby a series of grinding wheels may be mounted as a multiple unit on the same shaft in predetermined angular positions for simultaneously grinding a series of work shapes, such as several cams .on the same camshaft.

It is desirable to avoid a construction in which it will be necessary to utilize a special grinding wheel for each grinding position when employing the aforementioned method of grinding a set of work pieces, such as the familiar types of camshaft utilized in many multicylinder internal combustion engines, wherein a series of duplicate cams must be ground on these shafts in their different angular positions. If a special grinding wheel were used for each individual grinding position when grinding work of this type, it would involve heavy expense in wheel manufacture as well as much difficulty in wheel replacement, since each wheel `would not only need to be shaped as the conjugate of the individual work piece which it is intended to grind, but it would also have to be so formed when manufactured that it could be mounted only in a definite conjugate relation to the work. It will be appreciated that such a construction would necessitate that each machine operator maintain a large variety of different and carefully labeled wheels in stock, as well as that the wheel manufacturer would find it necessary to keep a master form for each wheel. i

It is, therefore, a still further object of this invention to provide a grinding wheel and mount assembly wherein a series of interchangeable grinding wheels duplicate in form may be axially supported adjacent to one another for simultaneous rotation, each wheel being held in any one of several definite angular positions relative to its support so that each may be used to grind any one of the conjugate surfaces on the work piece.

With these and other objects in view, as will be apparent to one skilled in the art, this invention resides in the combination of parts set forth in the following description and appended claims.

In the drawing illustrating a wheel and wheel mount embodying this invention:

Fig. 1 is a sectional view taken through a multiple wheel unit showing one form of the present invention as applied to grinding a series of duplicate cams on the same shaft;

Fig. 2 is a view taken along the line 2-2 of Fig. 1; and

Fig. 3 is an end view of the camshaft, showing the relative angular positions of the cams thereon.

In the embodiment of this invention illustrated in the drawing, there has been provided a grinding wheel and mount construction wherein a plurality of duplicate grinding wheels may be mounted as a unit so that each wheel may be held in a fixed predetermined angular position relative to a supporting shaft, whereby a given portion of each y grinding wheel may cyclically engage a given portion of the work when the work rotation is maintained in a synchronous angular relation to the wheel rotation. The grinding wheels of the assembly may be mounted on a spindle or drum and secured in position by clamping anges, and the individual wheels may be separated by spacing members, such as rings of metal, paper and the like. To positively locate each grinding wheel of the assembly in anyone of several predetermined angular relationships to the wheel supporting drum and thereby mount the whels in correct phase relationship with the work, each wheel has been provided with a series of locating devices, each of which has the required angular relation to a given radius passing through a predetermined point on the wheel periphery. Such a locating device may comprise a shoulder, recess or boss on the wheel, or a shoe or other suitable member may be secured to or made integral with the wheel, which has a definitely located surface, edge, or other portion precisely positioned with a definite angular relationship to a radius passing through a given point on the wheel periphery, which may be aligned or engaged by an accurately shaped member on the wheel mount to precisely locate the grinding wheel therewith in various predetermined angular positions.

It will be appreciated that the scope of this invention covers a condition wherein the accurately shaped member is carried by the grinding wheel and the locating devices are on the wheel mount. In'the preferred embodiment of this invention, the locating devices may be composed of metal, hard rubber, a resinoid or other suitable material on the wheel and have prelocated surfaces, edges, or holes which may be aligned with an accurately shaped member on the wheel mount to definitely locate the grinding wheel in one of several predetermined angular relations with its mount.

The accurately shaped locating member on the mount, as illustrated in the drawing, may comprise a locating pin or other similar device engageable with the wheel support in a definite position and also engageable with any of the locating devices on the wheels which, in the present instance, may comprise bushings of a suitable metal secured to the individual wheels and having holes which lie in predetermined angular relations to a radius of the wheel passing through a given point on its periphery. A suilicient number of said locating devices correctly positioned relative to each wheel has been provided so that all of the grinding wheels of the assembly may be made in duplicate form and interchangeably mounted upon their support. It will be appreciated that in assembling the various grinding wheels upon their supporting drum, it is simply necessary to position each wheel so that the locating member on the mount is aligned with the correct wheel locating device, thus providing means whereby the Wheels may be mounted in any one of several predetermined angular positions relative to their mount.

The preferred embodiment of this invention, one form of which is illustrated in the drawing, may comprise a grinding wheel supporting drum 25 arranged to carry a plurality of grinding wheels and having a hub portion 26 connected thereto by means of flanges 27. The hub 26 is slidably mounted upon a driving shaft 28 and secured for `positive rotation therewith by any convenient means, such as the keys 29. To prevent axial movement of the wheel supporting drum relative to the driving shaft 28, the hub 26 may be positively secured in accurate longitudinal relation thereto in any well-known manner, which in the present instance may comprise a flanged portion 32 of the driving shaft, against which the hub 26 may be securely clamped by means of a nut 33 screwed upon a threaded portion 34 of the drive shaft and serving to clamp against the opposite end of the hub 26.

A work blank 40 comprises, in the present instance, an automotive camshaft having sixteen cams integral therewith, as indicated by the consecutive numerals 1 to 16. The camshaft 40 is mounted for rotation between any suitable type of headstock 42 and tailstock 43 having the respective centering'members 44 and 45 rotatably engageable with said shaft. The headstock 42 isiprovided with a rotatable driving member 47 positively engageable within a slot 48 in the camshaft, whereby the rate and extent of angular camshaft movement may be positively controlled. In this type of grinding operation, the axes of the grinding wheels and the work are xed relative to each other during the grinding operation, except for the relative feeding of the work and wheels to reduce the work'to a required size. s

In the familiar type of automotive internal combustionengine, the camshaft serves to periodically operate various valve mechanisms through duplicate cycles at dierent times; hence, it will be appreciated that the cams numbered l to 16 on the camshaft may be duplicate in form but must have different angular relations, as shown in Fig. 3. Since the contour of the grinding wheel is utilized todetermine the shape of the work, it is essential that the rotation of the grinding wheel and the work be angularly synchronized so that the specially shaped operative wheel face will produce a conjugate surface on the work which will be the work shape required. In the present illustration, the grinding wheels and work contours are shown of such shape that the camshaft 40 and wheel shaft 28 are always rotated through the same angle. In other words, for-each rotation of the work, the grinding wheel contacting therewith is rotated a single revolution so that corresponding portions of wheel and work may always remain in correct relation. It will be appreciated that the angular velocities of the work and wheel may be in any simple ratio, such as 1 to 1, 2 to l, 3 to 1 etc., depending upon the contour to which the grinding wheel is shaped and upon the shape of the work required. Itis essential, however, that the grinding wheels and the work must be rotated through a proportionate angular displacement. To accomplish this, anyv suitable drive mechanism may be provided, such as that shown in the aforementioned co-pending application of Stubbs.

Since the cams 1 to 16 on the camshaft 40 are to be nished duplicate in form, but at different angular displacements, it will be appreciated that said cams may be simultaneously ground by sixteen separate grinding wheels all formed to the same contour but angularly displaced on drum 25 to such positions that each wheel will lie in correct angular relation with that of the corresponding conjugate cam to be nished. To accomplish this, a locating member has been provided which may be positively engaged with each of the grinding wheelsin any one of the required said drum to perform a simultaneous grinding operation upon all of the cams. To accomplish this, a series of wheel clamping anges are provided which have a locating member passing therethrough and positively engaging one of the.

locating devices on each grinding wheel which lies in the correct predetermined angular position. As illustrated, the preferred type of construction embodies an annular flange portion 50 integral with and substantially central of the wheel supporting drum 25, which projects therefrom a suilicient distance to aid in supporting a grinding wheel when clamped thereagainst. The flange portion 50 is provided with two opposed side ,faces 51 and 52 whichrare substantially parallel and perpendicular to the axis of the wheel shaft 28 and are adaptable to engage the side faces of adjacent grinding wheels 8A and 9A which, in the present case, serve to grind cams 8 and 9. The side faces 5l and 52 are preferably undercut adjacent to the periphery of drum 25 to provide a better wheel support. A series of annular wheel spacing and clamping rings 55 is further provided and arranged for axial but non-rotative movement relative to the supporting drum 25. These rings are of proper width to serve in spacing the grinding wheels in correct alignment with the, respective cams to be ground. Each of the rings 55 is provided with two opposed side faces which are substantially parallel and perpendicular to theaxis of the wheel shaft 28. These side faces are undercut adjacent to the drum periphery in the same manner as the side faces 51 and 52 of flange 50. As a further feature, each of said rings 55 is provided with a plurality of depending portions 57 adapted to slidably t within recessed portions 58 in the periphery of drum 25, whereby said rings may slide axially on the drum but are constrained for positive rotation therewith.

Clamping flanges 60 and 61 are adjustably fastened to the ends of drum 25 by means of screws 63 which serve to force said flanges into positive engagement with the end grinding wheels 1A and 16A. Since the rings 55 are slidably mounted on drum 25 axially thereof and are constrained to rotate therewith, said rings will also serve as clamping flanges and all of the wheels on drum 25 will be positively clamped in driving position when the end flanges 60 and 61 are clamped tightly against the end wheels.

To obviate the necessity of making a plurality of different wheelswhich in the present instance would require 16 dinerent wheels or one for each different angular cam position, there has been provided a means whereby an indexing or loeating member may engage'each wheel in any one of the required dierent angular positions. To accomplish `this, an indexing pin 65 has been provided, said pin being slidably engageable with and passing through holes within each of the end flanges 60 and 6l and a hole in each of the rings 55 and also a hole passing through the flange member 50. Since none of the rings or flanges are rotatable relative to drum 25, the holes are always in alignment to receive the pin 65. Each of the grinding wheels during manufacture is'made to a master form and is provided with a series of holes 1B, 2B, 3B etc. at the correct radial distance from the wheel'axis to re'- ceive the pin 65. Each of these holes is preferferably hushed `with babbitt or other suitable material 66 which constitutesa shoe or aligning surface. These surfaces are so positioned at equal radial distances from the wheel centers that when the wheels are mounted on the drum 25, it is only necessary to pass pin through the correct hole and each grinding wheel will be indexed to the proper angular relation with its respective cam. To `facilitate positioning pin 65 in the correct hole, each hole may be labelled during wheel manufacture with a number of other indication showing which cam the wheel is in correct angular alignment with when the indexing pin 65 is passed through that hole. For example, as shown in Figs. l and 3, when the index pin 65 is passed through hole 14B, the wheel is in correct angular relation to grind cam 14. When assembling the grinding wheels on the supporting drum 25, it is simply necessary to assemble each wheel with the correct hole aligned with pin 65, whereupon all of the wheels may be duplicate in form but angularly positioned with correct relation to the individual cam to be finished so that all of the cams may be simultaneously ground in the same operation. The pin 65, in addition to rving as a locating member, may also serve if desired as a driving member to supplement the clamping plates and make it unnecessary to clamp them against the fragile wheels with a heavy pressure.

It will be appreciated that the metal bushings 66 and the locating pin 65 slidably mounted therein may be replaced with other suitable types of locating devices. For example, the plurality of correctly located holes may be madein each of the rings 55 and a single accurately positioned bushed hole may be provided in each wheel, said vhole being located in the same position in each wheel relative to similarly located points thereon, such as a radial line passing through the central portion of that zone of the wheel which serves to grind the nose of the cam. A short pin or stud may be inserted in each wheel bushing and project therefrom into any one of the correctly located holes in an adjacent ring. The claims are to be interpreted as fully covering such or an equivalent construction. Itwill further be appreciated that the claims also apply to angularly locating a circular grinding wheel, which has a sector varying in grade or other characteristics from the rest of the wheel, in any one of several predetermined angular positions, whereby a certain portion of the wheel would be caused to remain in a given angular relation to a given portion of the work during a grinding operation.

Having thus described the invention, what is claimed as new and desired to' secure by Letters Patent is:

1. A grinding devicecomprising a rotatable support for a ding wheel, an abrasive wheel having a peripheral grinding face and a distinctive grinding sector capable of effecting a different grinding operation from that produced by another portion of the periphery, means to removably secure the wheel to said support for rotation therewith and for angular orientation relative thereto, and means including a locating device on the support arranged to positively engage the wheel and locate it in any one-of several predetermined angular positions on its rotatable support relative to a given radius in said sector.

2. A grinding device comprising a rotatable grinding wheel support, a bonded abrasive grinding wheel having a preshaped continuously curved peripheral face lying at a varying distance from its axis of rotation and mounted on the support for rotation therewith and for'angular orientation relative thereto, one of said parts having a plurality of locating devices thereon, each of said devices being provided with a locating portion accurately located in a predetermined position relative to a radius passing through a given point on the wheel periphery, and the other part having an accurately shaped member which may be precisely aligned with any one of said accurately located portions, and clamping means securing the grinding wheel in position, whereby it may be mounted on the support in any one of said predetermined angular positions relative to its support.

3. A grinding device comprising a rotatable support for a grinding wheel, a grinding wheel having a peripheral grinding face and a distinctive grinding sector varying in structure from the rest of the wheel and capable of eiecting a different grinding operation from that produced by other portions of the wheel periphery, means to removably secure the wheel to said support for rotation therewith, and means including a locating device on the support arranged to engage the wheel in any one of several predetermined angular positions on its rotatable support relative to a given radius within said sector.

4. A grinding device comprising a rotatable support, for a grinding wheel, a grinding wheel removably secured thereon having a peripheral grinding face and a distinctive grinding sector, said wheel having Aa plurality of locating shoes aiiixed thereto which have accurately positioned portions relative to a given radius in said sector serving to determine the angular position of the wheel, and an accurately shaped member secured tothe wheel support which may have the accurately positioned portion of any one of said shoes aligned therewith to positively locate the wheel in any one of several predetermined angular positions relative to its support whereby said sector may be oriented to a desired position relative to the wheel support.

5. A grinding device comprising a rotatable support for a grinding wheel, a bonded abrasive grinding wheel having a continuous curved peripheral face lying at a varying distance from its axis of rotation and a distinctive grinding sector whichhas different grinding. characteristics from the remainder of the wheel, said wheel having a plurality of locating shoes alxed thereto which have accurately positioned portions relative to a given radius passing through said sector and serving to determine the angular location of the grinding wheel, an accurately shaped member on the wheel `support which is so located that it may have the accurately positioned portion of any one of said shoes aligned therewith toexactly locate the grinding wheel in any one of several predetermined angular positions relative to its support whereby the distinctive lgrinding sector may be oriented to a desired position relative to the wheel support. p

6. A grinding wheel assembly comprising a rotatable support, a grinding wheel removably secured thereon and arranged for rotation therewith and for angular orientation relative thereto, said wheel having a peripheral grinding face and a distinctive grinding sector, a plurality of locating shoes on the wheel, each of said shoes having a surface -accurately located angularly relative to a definite radius of said wheel sector, a mem-V ber accurately positioned relative to the rotatable support, and means to positively engage said member with any of said locating surfaces, whereby the grinding wheel may be mounted on its support in any one of several predetermined angular relations thereto.

7. A grinding wheel assembly comprising a rotatable wheel support, a grinding wheel removably mounted thereon for angular orientation relative thereto, said wheel having a peripheral grinding face and a distinctive grinding sector, a plurality of locating devices ailixed on the wheel in predetermined angular positions relative to a given radius of the wheel,.means including clamping members secured to the wheel support and engageable with the side faces of the Wheel to rotatably support it, a locating member engageable with said clamping members and wheel support in a xed position, and means to positively engage said locating member with any one of the wheel locating devices, whereby the grinding wheel may be positively located in lany one of several predetermined (definite angular positions relative to its support.

8. A grinding wheel assembly comprising a rotatable support, a grinding Wheel removably secured thereon having a peripheral grinding face and a distinctive grinding sector, bushings accurately secured tothe wheel at predetermined angular positions relative to a definite radius in said sector and arranged at equal distances from the axis of wheel rotation, and a wheel positioning member accurately located relative to the wheel support and positively engageable with any one of the bushings, whereby said wheel sector may be oriented to and maintained in any one of several predetermined angular positions relative to the rotatable wheel support.

9. A grinding wheel assembly comprising a wheel mount arranged to axially support a series of adjacent grinding wheels, each of which is provided ywith a peripheral grinding face and a distinctive grinding sector, clamping members secured to the wheel mount and arranged to be clamped in place on the mount, locating devices on each of said wheels secured to said wheels in various predetermined positions, and means supported on the wheel mount which is positively and simultaneously engageable with one of the locatingdevces in each of the grinding wheels, whereby each of said wheels may be oriented to and located in various predetermined angular relations to the wheel mount.

l0. A grinding wheel assembly comprising a rotatable wheel mount arranged to axially support a series of adjacent spaced grinding wheels, each of which is provided with a peripheral grinding face lying at a varying distance from its axis of rotation and a distinctive grinding sector having grinding characteristics differing from the remainder of the grinding wheel, clamping members secured to the wheel mount and arranged to be clamped in position thereon, locating devices on each of the grinding wheels secured thereto in various predetermined positions relative to a denlte radius passing through each sector, and means supported on the wheel mount which is positively and simultaneously engageable with one of the locating devices in each of the grinding wheels, whereby each of said wheels may be oriented and the respective grinding sectors may be located in various predetermined angular relation tothe wheel mount.

11. A grinding wheel assembly comprising a r wheel mount arranged to rotatably support a plurality of duplicate interchangeable adjacent grinding wheels each of which is provided with a peripheral grinding face and a distinctive grinding sector, means carried by the wheel mount arranged to clamp against the side faces of each grinding lwheel and impart rotation thereto, locating devices on each of the wheels, said devices being positioned at equal distances from the axis of rotation of said wheels and at predetermined angular relations to each other, and means including a wheel locating member removably secured to the wheel mount and engageable with any one of the locating devices on each wheel, whereby the grinding wheels may be interchangeably positioned and oriented upon their support to locate said sectors in various predetermined angular relations thereto.

12. A multiple `grinding wheel unit comprising a wheel mount including a rotatable drum arranged to axially support a plurality of duplicate annular grinding wheelsthereon in close proximity to each other, annular spacing members between the adjacent wheels secured to but axially slidable on said drum, clamping flanges engageable with the end faces of the grinding ywheels mounted on each end of the drum and adjustably secured to said drum, whereby the wheels may each be rmly clamped in position, a wheel positioning device mounted on the drum in a definite position, and means, including a plurality of stations in predetermined locations on each grinding wheel, any one of which may be engaged by said positioning device, which serves to positively maintain each grinding wheel in any one of several predetermined angular locations relative to the wheel mount.

13. A multiple grinding wheel unit comprising a rotatable supporting hub for"r a plurality of grinding wheels, a series of interchangeable annular non-circular grinding wheels supported on the periphery of said hub, wheel spacing members slidably secured to the hub, clamping devices serving to secure the grinding wheel unit on the hub for rotation therewith, duplicate similarly positioned locating devices amxed to each wheel, said devices being located at equal distances from Athe axis of wheel rotation and at various predetermined angular positions relative to a given `wheel radius, and means, including a locating member mounted on the hub and movable parallel to its axis, which may be positively engageable with each of the grinding wheels at any one of the locating devices, whereby corresponding portions of each grinding wheel may be fixed ln any one of several definite angular relations with reference to the supporting hub.

THURE LARSSON.

Images