US1990927A - Multiple unit grinding wheel - Google Patents

Description

Feb. 12, 1935.

H. W. H. BETH MULTIPLE UNIT GRINDING WHEEL Filed Jan. 20, 1933 Hal HUGO PK H. BETH Patented Feb. 12, 1935 UNITED, STATES 1,990,927 MULTIPLE UNET GRINDING WHEEL Hugo W. H. Beth, Worcester, Mass, assignor'to Norton Company, Worcester, Mass, a corpora tion of Massachusetts Application January 20, 1933, Serial No. 652,599

5 (Zlairns.

This invention relates to a multiple unit grinding wheel wherein several separately manufactured grinding wheel units are secured together to form an integral grinding wheel adapted to grind a plurality of spaced surfaces.

As disclosed in the prior application of Stubbs, Serial No. 612,232, it has been proposed to employ several specially shaped grinding wheels individually mounted in spaced relation on the same shaft to simultaneously determine the shapes of several work pieces or surfaces such as the cams on an automotive camshaft. In such a machine, the preshaped grinding wheels and work are rotated in angular synchronism or in a definite cyclic timed relation so that while each Wheel contacts with its corresponding work surface, certain portions of each wheel periphery will always engage certain portions of the work, and the rotation of the wheels and work will always remain in a fixed angular phase relation causing each specially shaped grinding wheel to form a specially'shaped work contour which is the conjugate thereof.

The term"conjugate as applied to the shape of a grinding wheel relates to that curved wheel shape which will remain in rotative contact with the surface of a work piece which is of such shape or is so mounted that the line of grind! ing contact varies in its distance from the axis of grinding wheel rotation, while the wheel axis and work axis are maintained relatively stationary except for feeding the wheel into the work, and provided that the Wheel and work are rotated with angular Velocities equal-or in a simple ratio, the grinding operation being caused-by the unequal length of wheel and work surfaces which are moved relative to each other as they are roe tatedin angular synchronism,

Due to the fact that many types of work such as multi-cylinder automotive Camshafts have their grinding surfaces in very close proximity to each other, it has been found extremely difiicult to provide sufficient support fora plurality of large diameter, narrow, closely spaced grinding 1 Wheels. Grinding wheels of this type are very fragile and due to insufficient driving and lateral support therefor, breakage is frequent. Grinding wheels as used for such a multiple cam grinding operation may have an approximate diameter of 42 inches and a thickness of of an inch and the spacing between adjacent wheelsmay be as close as of an inch or more. It will 'be appreciated that due to the fragile construction of such a wheel, even a slight side thrust of the work ther a ainst mi ht n t break it, causin probable damage to the grinding machine, spoilage of the work and injury to the machine operator.

It is, therefore, the primary object of my invention to provide a multiple unit grinding wheel wherein several relatively narrow, large diameter grinding units may be secured together as a strong easily transportable integral wheel adapted for grinding a plurality of spaced surfaces wherein the opposed side faces of adjacent units are supportedagainst side pressures by a wearable material which does not interfere with the grind ing operation as the grinding wheel wears down in size.

It is a further object of this invention to provide a multiple unit grinding wheel having a plurality of spaced specially shaped grinding units which are held together and have their opposed side faces supported by a cementitious wearable material which will not interef ere with grinding operations, thereby formin an integral wheel unit.

S ce the special shape of each individual grinding annulus serves to determine the shape of its product work piece in a conjugate grinding operation, it willbe appreciated that con,-

siderable difiiculty might be encountered in angularly locating various wheels during the assembly of a multiple wheel as herein proposed.

It is, therefore, astill further object of this invention to provide an integral grinding wheelof multiple unit construction wherein the, in dividual rinding units may be positively alignedin correct angular relation to each other when secured together as an integral wheel and where in the assembled wheel canonly b mounted with a predetermined fixed angular relation to its sup:

port. 1

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 forthin the following description and appended claims.

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

Fig. 1 is a sectional view taken through a multiple wheel unit showing one form of my invention, and V p Fig. 2 is a view taken along the line 2- -2 of Fig. 1.

in the embodiment of this inventionas illustrated in thedrawing, there is provided a multiple unit grinding wheel wherein a plurality of individual grinding discs or bonded abrasive annuli are positively secured together in fixed spacedrelation in Such manner as to provide an integral easily transportable grind n h l i has a .sembly may be secured together to form an integral wheel by cementing the spacing members or hubs firmly to the adjacent grinding units or annuli of the assembly, and-the spaces between the adjacent grinding annuli may be filled with any medium which will easily wear away during the grinding operation and which will aid in supporting the side faces of the grinding annuli. The cement securing the wheels together and the filler between the adjacentgrinding annuli may be of the same or different materials. It is essential, however, that the filler between the adjacent annuli be composed of an easily wearable or friablematerial which will substantially fill the intervening space, transmit the lateral thrusts and yet will not interfere with the grinding operation as the grinding wheel wears down in size.

When using specially shaped grinding wheels as required in a conjugate grinding operation, it is necessary to locate the adjacent grinding units of the wheel assembly in predetermined angular relations and to further mount'theintegral wheel assembly in a predetermined angular relation to 1 its support so that the multiple unit wheel-may be angularly positioned, with each ofthe grinding' annuli in correct angular relation withthe. work. To accomplish this, each individual wheel .is'provided with an accurately positioned locatmy wheel, it is only necessary to assemble the proper units and align their locating devices. When the cement has set, with the individual wheels angularly aligned withtheir locating de vices in correct relation to one'another, it is simply necessary to mount the integral wheel assembly with the locating devices correctly positioned with reference to a given point on the wheel support whereupon ithewh'eels' maybe secured in correct angular relation fora grinding operation.

The preferred embodiment of this invent ion, one form of which is illustrated in the" drawing, may comprise a multiple unit grinding wheel'lO adapted to'grind a'pluralityof spaced surfaces and composed of a plurality of spaced separate, bonded abrasive, discs which are" secured together to form the integral grinding member 10;

' In the present instance, the wheel 10 comprises four abrasive annular discs 11-, 12; 13 andfl securedtogether in spaced relation and arranged'to grind four separate work surfaces such'as the cams on a product camshaft 21 in the same manner as shown in the application of Stubbs, Serial The various abrasive discs are separated by spacing membrsQwhich, as illustrated, may be formed integral withthe abrasive units. That is, the discs 11, 12 and 13 are'provided'withprotruding portions or hubs-24, 25 and '26respectively which are of such size and'shape as toserve in separating the adjacent grinding discs and locatture.

ing them in the desired spaced relation. It will also be appreciated that these portions 24, 25 and 26 need not be integral parts of the abrasive discs as shown but they may comprise separate pieces of metal, paper, fiber or any other suitable material adapted to serve the purpose of separat-.

ing the adjacent grinding annuli as'required.

To secure the separate abrasive discs into an integral grinding wheel structure which may be mounted on any suitable support for rotation as a unit, I preferably secure the protruding portions or hubs 24, 25, and 26 to the faces of the adjacent grinding discs with a suitable cementZS while the abrasive discs are co-axially held together in any suitable manner. litharge and glycerin, sulphur, lavasul (which is a mixture of ground coke and sulphur), or other suitable materials may be employed to cause the adjacent abrasive discs to be firmly secured together into an integral grinding wheel struc- For example, the protruding portions 24, 25 and 26 of the discs 11, 12 and 13 may be coated with any cement adapted to hold the discs together and then the discs may be co-axially supported and firmly held together until the cement Cements composed of has set and of itself serves to hold the wheel units to adjacent opposed faces of the grinding discs.

To provide the maximum grinding wear for a 7 wheel of this type, the separators 24,,25' and 26 are preferably as close to the wheel axis aspossible so that they may, not interfere with the grinding operation and the individual grinding discs are preferably of a large diameter as compared to their thickness. 7

It will be appreciated that ceramic bonded abrasive discs of such size are very fragile anda're subjected to frequent breakage unless properly To accomplish this, the interveninging ope'rationas the peripheries'of thegrinding discs wear down in size; By' providing 'a construction'of this type itwill be appreciated that any side shocks or pressures upon the end discs 11 or 14 will be transmitted through the entire wheel structure to be absorbed thereby and the entire wheel structure will be substantially as strong as a single abrasive wheel of comparable size. g i

It will be appreciated that the scopeof this invention is intended to cover any suitable filler between the adjacent opposed wheel faces. This filler'30 preferably comprises a. suitable cement and particularlythe same cementitious medium which is utilized to secure the adjacent abrasive discs together into an integal structure, in which case the wheel will be strengthened by the cement adhering to theopposed' disc faces. It is essen-" tial, however, since this invention is primarily intended to provide an integral multiple wheel unit structure adapted forgrinding spaced sur-' faces, that the filler 30 be'of suflicient strength to offer a rigid support to the side faces of the grinding discs and be sufficiently friable and wearable so that it may not interfere in any way with the grinding operation as the wheelwears down in size. It is also preferable that the material be non-abrasive so as not to affect the work being ground if it should engage the same. Lay'- asul and-'litharge cement'arejparticularly suit able for a wheel used for a cam grinding operation. If a non-cementitious filler is employed, it is preferable'to cement'it-to'the opposed disc faces and make the parts integral. It is to be understood that my invention is' also intended to cover the use of a filler between theadjacent grinding annuli which does not completely fill the intervening spaces therebetween but which may be in the form of spaced ribs or supporting posts sufliciently close to one another to provide ample lateral wheel support. I

When a multiple wheel unit of this type is to be employed for simultaneously grinding the cams'on an automotive camshaft, it is essential that each grinding disc of the multiple unit grinding wheel be specially shaped as the conjugate of the desired finished work contour and mounted and maintained in correct phase relation with the work so that the shape of each grinding disc may form the desired work shape in the'required angular relation. 'To accomplish this, each grinding disc has been provided with a locating device which has the required angular relationship to a given radius passing through a predetermined point on the'specially shaped disc periphery. Such a locating device may comprise a shoulder, boss or recess'oh 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 passingthrough' a given point of the wheel periphery, whichmay be aligned or engaged by an accurately shaped member on the wheel mount to precisely locatethe grinding wheel therewith in a predetermined angular position. 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 pre-located surfaces, edges or holes which may be aligned with an accurately shaped member on the wheel mount to positively locate each grinding disc in a predetermined angular relation to the adjacent disc in the assembled unit and also to the wheel mount.

In my preferred construction as illustrated, each of the grinding discs during manufacture may be shaped to a master form and provided with a hole passing therethrough which is the required radial distance from the wheel axis and which is placed at the required angular relation to a given radius passing through a given point in the periphery of the disc. Each hole is bushed with babbitt or other suitable bushing material which constitutesa shoe or aligning surface to aid in angularly locating each grinding disc in correct phase relation with the respective product cam.

To facilitate wheel assembly, each abrading disc may be marked with a number or other designating feature indicating which cam the disc is intended to grind. When assembling a multiple wheel unit as shown in Fig. 1, it is simply necessary to assemble the individual grinding discs and spacing members in the required order with the holes in bushings 35 aligned and the discs coaxially located relative to each other. After the cement 28 has set, the grinding discs will-firmly adhere together into an integral wheel structure. If'the filler 30 comprises a setable semi-fluid material, such as a cement, it may now be filled in between the adjacent grinding'annuli. 1 I'he integral grinding wheel may be mounted for rotation in any suitable manner with the wheel held in fixed angular relation to its support. To accomplish this, a wheel support 40 adapted to peripherally support the wheel assembly 10 is mounted'upon a driving shaft 42 and secured for positive rotation therewith by means of a key 43. 'To prevent axial movement of the wheel support relative to the driving shaft 42, the support maybe positively secured in accurate longitudinal relation thereto inany convenient manner, which in the present case may comprise a flanged portion 44 on shaft 42 against which the wheel support may be securely clamped by a nut 46 screwed upon a threaded portion 47 on shaft 42 and acting to clamp against the opposite end of the wheel support 40.

To secure the wheel assembly 10 on its rotatable support 40 in fixed angular relation thereto and for positive rotation therewith, a locating member, which in the present instance may comprise a pin 50 is slidably engaged within'the bushings 35. Clamping flanges 52 and 53 are secured to the opposite ends of the wheel support it) by means of screws 55 which serve to force said flanges against the opposite sides of the integral wheel assembly 10. Each of the flanges 52 and v 53 is provided with a recessed portion adapted to slidably engage and receive one end of pin 50 and thereby serve in angularly locating the wheel assembly. 10 in a predetermined angular relation with the driving shaft 42 which may be synchronized in its rotation with the camshaft as shown in the application of Stubbs, Serial No. 612,232. To prevent'incorrect assembly of the flanges 52 and 53, a locating pints is mounted in the end face of one end of the wheel support so that it may slidably engage a hole correctly aligned therewith in one of the wheel clamping flanges.

It will be appreciated that an integral grinding wheel structure of this type adapted to simultaneously grind a plurality of cams, may also be shaped after assembly. In such a case, the multiple unit wheel 10 could be built up from circular grinding discs and the individual grinding annuli could be trued to the desired contours by suitable devices to provide correctly shaped grinding peripheries each of which is in phase relation to the work and is shaped as the conjugate form of the desired work shape. It will further be appreciated that several of my multiple unit grinding wheels could be mounted upon an elongated wheel support in spaced relation to simultaneously finish any 7 desired number of spaced work surfaces.

It is to be understood that the present invention is not limited to a grinding wheel having a plurality of specially shaped non-cylindrical abrading surfaces, but may apply to any type of multiple unit grinding wheel composed of a plurality of separate, spaced grinding annuli held together as an integral grinding member and whose opposed side faces are supported against side pressures by an easily wearable material which breaks down and does not interfere with a grinding or 'truing operation as the wheels are reduced in size.

In the use of such a multiple wheel, it is often desirable to cut away the filling material slightly below the peripheral surfaces of the grinding discs so that it cannot engage the work during the grinding operation; and the claims herein Wheel adapted for grinding a plurality of spaced surfaces comprising a plurality of adjacent annular abrading members, space ing members located solely outside of the grinding zone which spacethe adjacent abrasive annuli at predetermined and material distances apart,

and a cementitious, relatively soft, non-abrading material located in the spaces between'the disks in the grinding zone, which will wear away during grinding without interfering with the grinding operation, said material servingto fill .the intervening space between the individual grinding annuli and support them, laterally and securejthem 'together'into an integral grinding wheel structure having spaced'grinding elements.

2.- A multiple unit grinding wheel adaptedifor g rindingspaced surfaces comprising a plurality of adjacent coaxial abrasive discs, spacing memoers located solely outside of the grinding zone and arranged to axially space the discs at'pree determinedand material distances apart, a cementitious medium securing the spacing mem-, bers to adjacent-disc faces and forming an inte-' gral grinding wheel,and a wearable material between the opposed faces of adjacent discs and in the grinding zone whichvsupports them individually against side pressures and which will be Worn away during the grinding operationwithout interfering with the abrading action of the wheel as itcis reduced in size; V 7

3[ A multiple unit grinding wheel adapted for grinding spaced surfaces comprising a plurality of adjacent coaxial grinding discs, spacing mem- 7 here integral with various discs to space them at predetermined distances apart, a cementitious,

medium securing the spacing members to the-adjacent disc faces and forming an integral grinding *WhGELIlIlitpfiIl-d a non-abrading, relatively soft, wearable material between the opposed faces of adjacent wheels which supports the individual discsagainst side pressures andrwhich will be worn away during the grinding operation withoutinterfering with ;.the abrading action of the wheel as itis reduced in size. or

4. A, multiple unit grinding wheel adapted for simultaneously grinding spaced surfaces comprising a plurality of adjacent coaxial grinding discs having central hubs projecting therefrom which serve to provide spacedgrinding annuli located at predetermined distances apart, a cernentitious, friable filler in the spaces, between the opposed faces of the annuli which willeasily wear away fwithout interfering with the grinding operation and-support the grinding wheels against lateral pressure, and acement to secure the hubs to the adjacent discs and form an integral grinding structure. 7

5. A multiple unit grinding wheel for simultaneously grinding a plurality of curved surfaces whose lines of grinding contact lie at different distances from the grinding wheel axis comprising a plurality of spaced, coaxial grinding-discs,

each of which is shaped as the conjugate of the work piece ground thereby, each disc being provided-with a portion aocurately'located in a predetermined angular relationship to a given point thereon, means to align saidlocating portions, means to fixedly secure'the discs coaxially together in said spaced relation with said locating portions aligned and thereby form an integral grinding wheel with eachdisc properly located 7 for grinding its work piece, anda filler of wear-- able material arranged to fill the intervening spaces between adjacent discs to support them laterally against. side pressures, said filler being the grinding operation asthe wheel is reduced in size; 7

' HUGO w. n. BETH.

of J such material that it will not interfere with

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