US2730848A - Form dressing tool - Google Patents

Description

Jan. 17, 1956 D, J. WALLACE ETAL FORM DRESSING TOOL.

Filed June 18, 1955 I7 .Z/"E .17 IE TE Dona/a z'f VVz/la as Leo Caa/Zo flw; H H

United States Patent 9 2,730,848 FORM n nssrNqTooL DonaldJ. Wallace and; Leo Catallo, Detroit, Mieln, assigners to Wheel Trueing Tool Company, Detroit, M c ac pora ion s De a zv re Application June 1953, Serial No. 362,603 2 Claims. (Cl. 51-404) The present invention relates to form dressing tools used for shaping peripheralsurfaces of grinding wheels and the like to provide them with accurately contoured working surfaces. The invention specifically relates to form dressing tools having diamond imbedded contoured surfaces to be used in conjunction with apparatus for abrading a grinding wheel to impart to the working surface thereof a preselected peripheral contour of accurate dimensions.

One of themore common methods for providing the periphery of an abrasive wheel with a desired profile involves the operation known as crush dressing. in this type of wheel dressing the periphery of the. abrasive wheel is brought intopressure centact with the tool having a contour which is the reverse of the configuration desired in the Wheel periphery, the tool. having a facing composed of hard metal or compounds such as silicon carbide, tungsten carbide and the like or appropriate softer materials. As the abrasive wheel is rotated, the hard surface of the tool presses into the periphery of the wheel, thereby crushing the vitrified binder matrix in which the, abrasive particles are imbedded, as well as crushing to some extent the. abrasive particles at the periphery, of the Wheel. Abrasive wheels bonded by resinoids, rubber and shellac do not lend. themselves to crush dressing because of their resilient nature. A crush dressing operation frequently has to be followed by a finish dressingoperation usingadiamond dressing tool in. order to bring the shape of the grinding wheel pe: riphery within the dimensional. tolerances required.

Furthermore, the pressures involved, in crush dressing, usually being on the. order f 100 to 500 pounds per square inch, put a substantial stress on the spindle of the abrasive wheel so that frequently, the abrasive wheel mustbe crush dressed on a spindle other than that which carries the wheel during the regular dressing operation. A new and improved method and apparatus for form dressing abrasive wheels forms part of the subject matter of our eopending parent application, Serial No. 277,562, filed March; 20, 1952, of which the present application is a continuation-impart.

object of the present invention is to provide a new and improved form dressing tool.

Another object of our invention is to provide a form dressingtool havingsurfaces complementary to the contourjimp arted to a grinding wheel or the like and having discrete abrasive particles imbedded in the surface of the tool.

Another object of the present invention is to provide a form dressing tool having a sintered matrix body formedwith surfaceswmplementary to the contour to be imparted to a grinding wheel or the like with discrete diamond particlesimbedded in said surfaces.

7 Still another object of the present invention is to provid a form dressing tool having a body of sintered refractory material such as any of the refractory metals or carbides of refractory metals, or mixtures of refractory metals andcarbides of refractory metals, andhaving surfaces complementary to the contour to be imparted to a grinding wheel with discretely divided diamond particles or other abrasive particles imbedded in said surfaces of the dressing tool.

Still another object of the present invention is to provide a form dressing tool for form dressing a grinding wheel, or a pair of grinding wheels simultaneously, the form dressing tool having asurface that is rectilinear in one direction and in the transverse direction is complementary to the. contour to be imparted to the grinding wheel, with finely divided diamond particles distributed over said surface and imbedded therein.

A still further object of the present invention is to provide a form dressing tool with abrasive particles so distributed over abroding. surfaces of the tool that at least one particle appears in substantially any line along the said surface.

A still further. object of the present invention is to provide a form dressing tool for abrading a pair of grinding wheels simultaneously to a preselected configuration, wherein the tool has a pair of substantially opposed surfaces contoured complementarily to the preselected contour to be imparted to the grinding wheel with discrete diamond particles so distributed over the abrading surfaces of the tool that at least one particle appears in substantially any line on said surfaces.

it is an additional object of. the present invention to provide a form dressing tool having an abrading surface which is rectilinear in one. direction and is contoured in a transverse direction complementary to the contour to be imparted to a grinding wheel or the like.

it is still an additional object of the present invention to provide a form dressing tool that preferably has an abrading layer of substantially single particle thickness provided by diamond particles imbedded therein.

Still other and further objects of the present invention will be apparent and present themselves to those skilled in the art and others reading this specification and the claims appended thereto and viewing the drawings with numerals of reference marked thereon forming a part of this specification, in which like numerals referred to like parts and in which:

Figure l is a partial elevational view of apparatus employing a form dressing tool of the present invention;

Figure 2 is a fragmentary side view with parts in elevation of the assembly of Figure 1;

Figure 3 is a front elevational view of a preferred embodiment of our form dressing tool;

Figure 4 is an enlarged sectional view of the tool illustrated in Figure 3 and is taken along the line lV-lV of Figure 3;

Figure 5 illustrates another embodiment of our invention and a workpiece or grinding wheel abraded by the use of a dressing tool made in accordance with our invention; and

Figure 6 represents an enlarged view of the cutting section of the form of tool illustrated in Figure 5.

There is illustrated in Figures 1 and 2 a mechanism and system for facing two grinding Wheels simultaneously and for employing a form dressing tool made in accordance with the present invention. Two grinding wheels 2th, ill have axes of rotation which are parallel to each other, and the wheels are mounted in the same plane of rotation. The wheels as shown are mounted in a vertical plane, but may lie in a horizontal or any other desired plane. The wheels 1%, 11 may be composed of abrasive particles imbedded inany of the common materials including citrified compositions, resinoids, rubber, or shellac, as the method and the dressing tools of our invention accurately form dress all those types of wheels.

The upper grinding wheellil is supported on a spindle l2 journaled in a bearing 13. A pulley Mcarried by the spindle 12 drives the wheel by means of a belt 15 associated with a drive motor 16. The grinding wheel structure, as well as the motor 16 are supported on an L-shaped bracket 17. The shorter leg 18 of the L-shaped bracket has a tongue formed therein received in a channel 20 of a vertical support 21. The leg 13 has an internally threaded bore 23 which receives a threaded rod 24, the latter being supported from the support 21 by means of a pair of vertically spaced ears 25, 26. A hand crank 28, secured to the threaded rod 24, is provided for rotating the rod 24, and by virtue of the engagement of the threads of the rod 24 with the threaded bore 23 of the leg 18, rotation of the hand crank 28 moves the. L-shaped support bracket 17, the grinding wheel 10 and the motor 16 in an adjusted vertical position.

The grinding wheel 11 is mounted in the same manner as that employed for mounting the grinding wheel 16. A spindle 30 carrying the grinding wheel 11 is driven by means of a pulley 31, a belt 32 and a motor 33 at a desired angular velocity. Preferably, the grinding wheels 10 and 11 are driven in opposite directions and at the same angular velocity. The motor 33 and the grinding wheel 11 are mounted on an L-shaped support bracket 35, the latter having an internally threaded bore 35 in the shorter leg thereof which engages the threads of a threaded rod 37. A hand crank 46 is provided to enable vertical adjustment of the L-shaped support bracket 35, and hence, the vertical position of the grinding wheel 11.

V The mounting of the form dressing tools of the prescut invention is best illustrated in Figure 2. The tool, further described below, consists of a tool body 42 having oppositely-contoured abrasive surfaces 43 and 44, which are preferably rectilinear in one direction and contoured in a transverse direction. The configuration of the abrasive surfaces 43, 44 will be opposite from that desired in the profile of the grinding wheels to be dressed, that is, the contour of the abrading surfaces of the tool will be complementary to the contour to be imparted and abraded into the peripheries of the grinding wheels to be operated upon by the form dressing tool of the present invention. Many different types of cutting tools can be employed for the purposes of the present invention as for example, a tool formed, using powdered metallurgy technique, from a mixture of tung- V sten and tungsten carbide and having finely divided diamond particles imbedded in the surfaces 43, 44. The size of the particles is quite small, being on the order of 50 to 500 particles per carat, or even much smaller where finish dressing is being done. A preferred range for particle size is on the order of 200 to 400 particles per carat where a substantially single diamond particle thickness of the diamond impregnated surface is to be provided.

if it is desired to form dress but one grinding wheel at a time, a form dressing tool in accordance with the present invention may be provided with only one abrading surface, as in the embodiment illustrated in Figure 5.

The form dressing tool body 42 may be secured to a carrier 45 by means of spaced securing bolts 46. The carrier 45 is also provided with a tongue which is slidably received within a channel 48 of a guideway 49. in order to distribute the abrading action over the full length of the abrasive surfaces 43, 44 in the rectilinear direction, the carrier 45 is reciprocated tangentially to the peripheries of the Wheels 10, 11 during rotation of the wheels, as illustrated in Figure l. The carrier 45 is secured to a rod 51 associated with a hydraulic cylinder 52, preferably a double acting type. A plurality of fluid inlct means 53, 54 are provided in the cylinder 52 for periodically reciprocating a piston (not shown) secured to the end of the rod 51 opposite the carrier 45, and reciprocablc within the cylinder 52.

In the form dressing of the grinding wheel 10, 11

the wheels are preferably rotated in opposite directions by means of their associated motors 16, 33 and preferably at the same angular velocity. As the grinding wheels 10 and 11 are rotated, pressurized fluid is introduced into the fluid inlet means 53, 54 associated with the hydraulic cylinder 52, thereby causing reciprocation of the carrier 45 and the tool 42 associated therewith. The spacing of the wheels 10 and '11 is suflicient to engage the abrasive covered surfaces 43, 44 of the dressing tool 42 to afford abrading contact between the peripheries of thegrinding wheels and the abrasive surfaces of the tool due to differential speeds, the pressure contact between the wheels and tool being less than crushing pressure. The tool 42 is reciprocated back and forth in the direction tangential to the peripheries of the wheels 10 and 11 in as many passes as necessary to abrade the periphery of the rapidly rotating grinding Wheels 10 and 11 into a configuration whichis complementary to and opposite to the configuration of the abrading surfaces 43, 44.

The abrading action tool, in contrast to the crushing action of crush dressing tools, provides an accurate form dressing tool for form dressing the periphery of the grinding wheels within close dimensional and contour tolerances. The tools of the present invention also provide for form dressing time substantially less than heretofore customary, and have the further advantage that the useful life of the dressing is substantially longer than other types of form dressing tools.

With specific regard to the form dressing tool of the present invention and particularly as it is illustrated in Figures 3, 4, 5 and 6, it can be seen that the dressing tool 42 can be provided with either one, two or more contoured dressing surfaces as desired. The body of the tool may be formed in any desired manner. It may be formed of rolled tool steel stock which is cut precisely in conformity with the contour preselected, rit may be cast of some hard material, or it may be molded and finished to have the preselected desired contourfor its abrading surfaces. One preferred method of forming the body of the tool is to precut mold faces to substantially precisely the configuration desired for the grinding wheels that are to be abraded by the tool, and then cover these precut faces with the abrading material such as diamond dust, or diamond particles. Following this, the mold is filled with a refractory powder which is substantially sintered so that it conforms substantially to the form of the mold and has the abrasive particles imbedded in its abrading surfaces and substantially only in those surfaces and not throughout the body of the tool.

tools of the present invention, to have the diamond particle layer providing the abrading surface a layer of single particle thickness. It is a waste of expensive material to imbed the diamond particles to a thickness greater than that of a single particle or at most a few particles if the particles are very fine, since the form of the tool and hence its utility as a form dressing tool are lost once the superficial surface diamonds become worn excessively or dislodged. r

A preferred method for forming form dressing tools of the present invention is fully described in our copending application Serial No. 280,464, filed April 4, 1952, of which this application is also a continuation-in-part.

As we have pointed out above, the form dressing tool of the present invention is preferably made of hard or refractory'materials for the body portion of the tool. Satisfactory refractory material includes the substantially pure metals or alloys thereof such as the high carbon and/or high silicon alloys, but preferably we use refractory metals based on the metals of Group VI-A and their carbides or mixtures of the same.

The metals of Group VIA, i. e., molybdenum, tungsten and chromium and their carbides, are preferable, and

It is particularly desirable in making form dressing we have found that a particularly preferred species to be employed in form dressing tools of the character of the present invention is that formed of a mixture of tungsten and tungsten carbide. It should be noted, however, that other hard and/ or refractory materials are available for use in constructing form dressing tools in accordance with the present invention and we do not intend to limit ourselves to the material disclosed hereinabove.

Referring again to Figures 3 and 4, the form dressing tool 42 may take any particular desired shape but when used in conjunction with apparatus such as that of Figures 1 and 2, preferably has a front elevational contour which is substantially rectangular and a pair of holes 61, 62 bored therein for the reception of such securing means as the bolts 46 (Figures 1 and 2). The diamond imbedded surfaces 43, 44 preferably are rectilinear in one direction and should conform substantially precisely, and be complementary to the contour to be imparted to the grinding wheels in a transverse direction. The diamond particles 63 should preferably be so distributed over the surfaces of the tool so that a diamond particle will appear substantially in every line that may be drawn on the surfaces so that the contour of the grinding wheels will be substantially smooth and all points on the grinding wheel subjected to the action of the tool will be of the proper height with respect to the remainder of the contoured surface of the workpiece or grinding wheel. This is to say that preferably the diamond particles should be so distributed over the surfaces of the tool that whenever a grinding wheel is abraded by the tool, the grinding wheel will be cut or abraded to a substantially precise configuration according to the preselected contour to be imparted thereto.

Form dressing tools according to the present invention may take most any desired contour and impart that contour quite precisely to a grinding wheel or other workpiece. Form dressing tools of the present invention are not limited in their configuration to substantially rounded contours such as that shown in Figure 4, but they may take that form if such form is desired. They may also take the form such as that shown in Figures 5 and 6 wherein substantially rectangular lands and grooves 73, 74, respectively, are abraded or cut in a grinding wheel, such as 70, to provide such a configuration and abrade the same in a workpiece or grinding wheel 70. A tool 71. is provided with a substantially precisely complementary contour of lands 75 and grooves 76 which are coated with diamond particles 72 in much the same way as the diamond particles 63 were provided on the surfaces 43 and 44 of the form dressing tool 42 illustrated in Figures '1, 2, 3 and 4.

Comparing Figures 3 and 4 with Figures 5 and 6, it will be noted that form dressing tools in accordance with our invention need not have two abrading surfaces, one on each of two opposite sides of the tool, but may be formed that way, if desired, to be employed with apparatus such as that described and illustrated with respect to Figures 1 and 2 to abrade two grinding wheels simultaneously, but tools in accordance with our invention may also be made with a single abracling surface such as that shown in Figures 5 and 6 if so desired. Additionally, of course, tools in accordance with our invention may also be provided with more than two abrading surfaces if so desired to be used with apparatus where more than two grinding wheels are to be form dressed substantially simultaneously.

It will be understood that modifications and variations in our invention may be effected without departing from the scope of the novel concepts of the present invention.

We claim as our invention:

1. A form dressing tool for imparting a preselected contour simultaneously to a pair of grinding Wheels, comprising a rigid tool body symmetrical about a longitudinally extending median plane and having on either side of said plane oppositely facing abrading work surfaces, each of an identical configuration that is rectilinear in longitudinally extending planes parailel to said median plane and non-rectilinear in all planes transverse to said median plane, and discrete abrasive particles forming a layer of substantially a single particle thickness embedded in said oppositely facing surfaces and exposed thereon, said particles being so distributed over said] work surfaces that at least one of said particles lies in any straight line extending in the rectilinear direction of said surfaces.

2. A form dressing tool for imparting a preselected contour to a grinding Wheel, comprising a rigid too] body having a working surface composed of longitudinal extending rectilinear elements and having other than a continuously rectilinear contour in all planes transverse to said rectilinear elements, and discrete diamond particles of particles per carat and finer embedded in said sur face and exposed thereon, said particles being distributed over said entire surface so that at least one of said particles lies exposed for abrading action in every one of said rectilinear elements, whereby said tool is effective in use to form dress a wheel to substantially the exact contour of said working surface.

References Cited in the file of this patent UNITED STATES PATENTS 122,573 Daniels Jan. 9, 1872 2,100,954 Gould et al. Nov. 30, 1937 2,197,655 Boyer Apr. 16, 1940 2,281,420 Drader Apr. 28, 1942 2,359,920 Keeleric Oct. 10, 1944 2,367,286 Keeleric M Jan. 16, 1945 2,396,015 Liden Mar. 5, 1946 2,443,370 Bakker June 15, 1948 2,662,519 Metzger Dec. 15, 1953 2,675,654 Harris Apr. 20, 1954 FOREIGN PATENTS 382,626 Great Britain Oct. 20, 1932 556,668 Great Britain Oct. 15, 1943 570,767 Great Britain July 20, 1945 576,452 Great Britain Apr. 4, 1946

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