US2239034A - Grinding wheel dressing fixture - Google Patents

Description

April 22, 1941. R. E. CROSS GRINDING WHEEL DRESSING FIXTURE Filed Feb. 12, 1940 2 Sheets-Sheet 1 INVENTOR April 22, 1941. R. E. CROSS GRINDING WHEEL DRESSING FIXTURE Filed Feb. 12, 1940 2 Sheets-Sheet 2 a 5 3 K 3. i 9

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ATTORNEY Patented Apr. 22, 1941 UNITED STATES PATENT OFFICE GRINDING WHEEL DRESSING FIXTURE Ralph E. Cross, Detroit, Mich.

Application February 12, 1940, Serial No. 318,498

2 Claims.

This invention relates to grinders and particularly to a means for dressing the grinding wheel thereof to a size and contour complementary to that desired in the surface of the finished workpiece and to the combination of such fixtures with a grinder, the principal object being the provision of a fixture of the type described that is simple in construction, efiicient in operation and economical to produce.

Other objects of the invention include the provision of a novel form of grinding Wheel dressers enabling the periphery of a grinding wheel to be quickly and accurately dressed to bring its section into complementary conformity to the cross-sectional configuration desired in the surface of a piece of Work; the provision of a device of the type described applicable to and removabl from an external grinder and including a part adapted to be releasably fixed in position and carrying a template having a surface of the size, shape and contour desired for the surface of a workpiece as viewed in the section taken perpendicularly thereto, together with means guided by the template in its movements with respect to the grinding wheel and carrying means engageable with the grinding wheel for dressing the surface thereof; the provision of a device of the type described in which the means guided by the template include a pointer engageable with the template and the means for dressing the grinding wheel is provided with a point of the same size and shape as the tracer point and arranged with its apex in a line including the apex of the tracer point and positioned perpendicularly with respect to the plane of movement of the first mentioned means; the provision of a device of the type described including a supporting part adapted to be releasably fixed to the work slide of a grinder and having a template carrying part adjustable to and from the c axis of the grinding wheel, together with means freely movable in one plane with respect to said supporting and template parts and carrying a tracer point engageable with the template and a dressing member engageable with a grinding wheel, the tracer point and the dresser means being so constructed and arranged that the periphery of the grinding wheel may be dressed to bring its cross-sectional size, shape and contour as viewed in the section taken perpendicularly to such surface o exact conformity with the size, shape and contour of the operative face of the template; and the provision of a grinding wheel dressing fixture of the general type described haw ing certain novel features of construction.

Other objects of the invention include the pro vision of an external grinder having a longitudinally reciprocable work slide and a grinding Wheel arranged with its plane approximately perpendicular with respect to the plane of .movement of the Work slide and arranged for bodily movement toward and fromthe work slide, together with a grinding wheel dressing. fixture cooperable with the work slide carrying a template having a face corresponding exactly in size, shape and contour desired on the periphery of the grinding wheel as viewed in a. plane taken perpendicularly thereto, together with a dressing member arranged for substantially free movement in a plane intersectingthe grinding wheel and approximately parallel with the axis of rotation thereon and including a tracer point engageable with the template and a dressing means for the grinding wheel aligned with the tracer point in a direction perpendicular to the plane of movement of said dressing member, the template being so positioned with respect to the periphery of the grinding wheel that when the latter is drawn toward the work slide and its faceis dressed by the dressing means into conformity with the template, the surface of the grinding wheel will be arranged in predetermined relation and at a predetermined distance from the path of movement of the work piece in the grinder.

The above being among the objects of the present invention the same consists in certain novel features of construction, and combinations of parts to be hereinafter described with reference to the accompanying drawings, and then claimed, having the above and other objects in new.

In the accompanying drawings which illustrate a suitable embodiment of the present invention and in which like numerals refer to like parts throughout the several different views Fig. l is a front elevational view of a representative type of external grinder to which a suitable embodiment of the present invention is shown applied;

Fig. 2 is an enlarged, fragmentary, transverse sectional view taken on the line 2--2 of Fig. 1 and illustrating a suitable embodiment of the present invention, in partially broken and partially sectioned View, in operative relation with respect to the grinding Wheel;

Fig. 3 is a still further enlarged, fragmentary front view of the grinding wheel dressing fixture shown in Fig. 2 and taken as on the line 3-3 thereof, and also illustrating a. fragment of the 7 previous views;

Figs, 7 to 10, inclusive, are views similar to Fig. 6 but illustrating templates having differently shaped surfaces which may be duplicated on the surface of the grinding wheel by the employment of the present invention when viewed in section taken perpendicularly to the operative face of the grinding wheel.

While the present invention is particularly adapted for use in connection with the dressing of grinding wheels employed in thread grinding, and for that reason the description herein will be principally limited to such use, it will be understood, that the invention is applicable to any job where the periphery of a grinding wheel is to be dressed to shape the surface of any cylindrical or plane workpiece. to provide the surface of the same with any desired configuration, and may be employed for any threads or other elements such as ribs, grooves or the like as desired to be formed on or in the surface of a circularly sectioned workpiece in either helically arranged or truly circular relation with respect thereto.

The grinding wheel. dressing fixture of the present invention is applicable to any suitable type of external grinder and may be employed in connection withgrinders of both the rotating type and the so-called surface or flat type. The particular grinding machine illustrated in Figs. 1 and 2 is shown merely by way of illustration of one suitable type of grinder to which the present invention is applicable although in a more limited sense the invention contemplates the combination of the grinding wheel dressing fixture with the particular type of grinder illustrated.

Referring to the drawings and particularly to Figs. 1 and 2 the grinder there shown includes a suitable type of base or frame indicated genorally at the upper surface of which may be provided with a pair of parallel ways 22 as indicated in Fig. 2. A work slide 24 is slidably received upon the ways 22 and is adapted to be reciprocatedthereon in a conventional manner by means of a rotating screw 26 fixed against axial movement in the frame 20 and engaging a nut 28 fixed with respect to the work slide 24. The particular type of work slide 24 shown is that having an angular face 30 although those skilled in the art will readily appreciate that the invention may be modified in a simple, well recognized manner to adapt it for reception by work slides having a horizontal work face in place of the angular work face 30 shown.

The base 20 is also provided with Ways 32 extending horizontally and in a direction perpendicular to the length of the ways 22 in which are slidably received a grinding wheel supporting head 34 provided with a rotatable shaft 36 which carries the grinding wheel 38. The grinding wheel 38 may be caused to advance toward or recede from the work slide 24 by means of a screw shaft 4% suitably mounted for rotational movement in the frame 20 in parallel relation to ways 32 and threadably engaging a nut 42 secured to the head 34. The outer end of the shaft d0 projects through the front wall of the frame 26 and is there provided with a gear 44 secured thereto. The gear 44 lies in mesh with a pinion (not shown) secured to the shaft 45 of a suitable hand wheel 48 mounted on the front face of the machine.

The work face 30 of the work slideE-l carries adjacent one end thereof a tail stock indicated generally at 59 in Fig. 1 andv adjacent the other end a head stock 52, the latter including a suitable rotatable driving center 54 which may be caused to rotate during operation of the grinder in a suitable and conventional manner. The

' tail stock 59 and head stock 52 are adjustable longitudinally of the work face 39 so as to adapt them to receive work pieces of different lengths between their respective centers. In the present instance the workpiece is assumed to be a cylindrical shaft having a threaded surface and indicated at in Fig, 2, the threads of which it is desired to grind.

V The grinding wheel dressing fixture in the particular form of the invention shown includes a base or supporting member 66 having a lower face 62 complementary to the work face 30 of ie work slide 25 and provided with a depending flange 64 at its upper or outer end as viewed in Fig, 2 adapted to be received back of the vertical shoulder 6'5 of the work slide 24. The cooperation of the flange 54 and the face 62 of the base cooperating with the shoulders 95 and the face 333 of the work slide 24 serves as a means whereby the dressing fixture may be accurately re-located on the work slide it after removal therefrom. The weight of the grinding wheel fixture will ordinarily be sufficient, when employed on a work slide of the type illustrated at 24, to maintain it in suitably fixed relation during a grinding wheel dressing operation, although it will be appreciated that where either necessary or desirable any desired type of separate means may be employed for releasably securing the base 60 in fixed relation with respect to the Work slide 24.

The support 80 is provided centrally of its width and at the inner end of its upper surface with a partially cylindrical pocket 58 the axis of curvature of which if extended will preferably substantially intersect the axis of the grinding wheel 38. Within the pocket 68 is received a block 76 the outer surface of which is curved into conformity with a partially cylindrical surface of the pocket 88 so as to enable the block Hi to be partially rotated therein about the axis of curvature of its periphery. It may be conveniently locked against movement in rotatably adjusted position by means of a clamp 1'2 and screw 14 cooperating between the inner face of the block iii and the inner face of the body 0 to clamp the block H3 against the rear face of the pocket 68.

The upper face of the block 18, as best shown in Fig. 3, is provided with a relatively wide dovetailed groove therein arranged in parallel relation with respect to the axis of curvature of the pocket 68. Within the groove it is received a slide 78 the position of which longitudinally of the groove may be adjusted by means of a screw The upper face of the slide 18 is planar and located in a plane parallel to the path of movement of the slide it.

At the inner end of the slide 78 a pair of arms 82 preferably formed integrally with the slide 78 at opposite sides thereof extend from the base the slide 78 perpendicularly with respect thereto and at their upper ends are joined together by means of, an integral cross arm 84 which as best illustratedein FigspZ and is provided with an extended boss portion 86 the inner face of which is provided with a groove 88 for reception of a template member 90 adapted to be removably secured therein by means of a screw 92 or other suitable means. As best illustrated in Figs. 2, 5 and 6 the particular form of the template member 90 shown by way of illustration comprises a main body portion of rectangular section, the lower end ofwhich is forwardly or outwardly turned as at 94 and the forward face of which outwardly turned end is machined or otherwise formed to provide an edge which in plan view, as illustrated in Figs. 5 and 6, is identical in shape and contour, and in some instances the size, to that which it is desired on the face ofthe grinding wheel and complementary to the shape and contour, and in someinstances to the size, of the periphery of the work as viewedin section taken perpendicularly to the surface of the work or in the case of a circularly sectioned work piece as shown by way of illustration, axially through the work. In the particular case illustrated and assuming that the workpiece isa threaded shaft or the like the threads-of which are desired to be ground, the operative face of the template is formed to provide a pointed projection 96 complementary in shape and contour to the groove desired between the threads in the workpiece.

Received upon the upper face of the slide 18 is a block I09 having a plain lower face and adapted to be moved into any position upon the upper face ofthe slide I8 between the arms 82. The inner end of the block I08, that is. the end toward the grinding wheel 38, is preferably inwardly tapered as best shown in Fig. 4 in order to increase the available amount of movement on the face of the slide 18 laterally between the arms 82 than would otherwise be permitted. In its inner face the block I00 carries a grinding wheel dressing element which will usually be and which is illustrated in the present case as consisting of a diamond I62 carried by a suitable support I04 in accordance with conventional practice. The diamond I02 is preferably positioned on the axis of rotation of the block 10 in the pocket 68 and, accordingly, on a horizontal line intersecting the axis of the grinding wheel 38.

Adjacent its upper end the block II!!! has fixed thereto a tracer point H16 which in plan view is provided with a pointed end portion exactly conforming in size, shape and contour to the diamond I82 and with the apex of its point positioned on a line including the apex of the diamond I82 and perpendicular to the upper face of the slide I8. Moreover the tracer point I06 is positioned at such height that when the block I00 is resting upon the upper face of the slide 18 the tracer point will lie in the plane of the operative face of the template member 92.

As will be appreciated by this arrangement, 1f the block I00 is slid about the upper face of the slide 18 with the tracer point I08 in contact with the operative face of the tracer member 98, the point of the diamond I02 will be caused to follow a path corresponding exactly to the path of movement of the tracer point I86 and if, for instance, the tracer point is caused to follow around the outer surface of the projection 96 on the tracer member 98 the diamond I02 in ex eouting the corresponding movements will, if 1n contact with the perip e y of the erindmg Wheel 38, dress the surface of the grindin Wheel 38 into exact conformance to the sh p of h P jection 96,. In this respect itwill be appreciated that regardless ,of the relative position of the block lilliabout a vertical axis, so long as its lower face remains in flat contactingrelation with respect to the upper face of the slide 18 and the tracer point I08 is caused to follow over the operative edge of the template member 98,

the-diamond I82. willube constrained to trace a path exactly equivalent to the operative face of the template and to dress the periphery of the grinding wheel 38, if positioned for engagement therewith, into exact conformity to. the shape of the-operative face of the template 90.

It will be appreciated that the slide I8 may be adjusted toward or fromthe grinding Wheel .38 so that the periphery of the grinding wheel 38 when dressed by the diamond I82 and as controlled in position and shape by the template 90 will be positioned at the exact distance from the axis of rotation of the workpiece 56 required to grindthe periphery of the workpiece to the desired or required diametrical dimensions. Once the position of the template 90 is thus located, each timethe periphery of the grinding wheel 38 requires re-dressing, the fixture may be simply applied to the Work slide '24, the grinding wheel 38 moved by the hand wheel 48 to advance it further toward the axis of rotation of the work, and then the block I00 moved to redress the periphery of the grinding wheel with the assurance I thereafter that the grinding wheel will grind the surface ofthe workpiece to bring it to the exact diametrical dimensions, desired therein and without requiring further checking of the workpiece and adjusting of the dressing fixture or the grinding wheel 38 to bring it into conformance with the dimensions desired in the workpiece. This feature is, of course, of importance particularly where a relatively large number of workpieces of identical size, shape and construction are desired to be ground one after the other.

Where the threads of a threaded shaft are to be ground and the threads are either of a square type, are usually deep, or have a relatively great lead, it is often desirable to tip the axis of the grinding Wheel 38 so as to bring the plane of the grinding wheel 38 into the same general plane as that portion of the thread of the shaft contacted at any one time by the periphery of the grinding wheel. Although not specifically shown in the drawings it may be assumed that the grinder illustrated is conventionally constructed to permit such tipping of the grinding wheel 38. In such case it will be appreciated that it will be desirable to tip or rotate the block "Ill so as to bring the upper surface of the slide 78 into a plane perpendicular to the plane of the grinding wheel 38 in such tipped relation. This may be readily accomplished in the construction shown by simply loosening the screw I4, rotating the block III in the pocket 68 until the desired relation between the upper surface of the slide 18 and the plane of the grinding wheel 38 is obtained, and then simply looking the block I0 against further rotation by re-tightening of the screw I4.

With the conventional type of grinding wheel dressing mechanism it is readily possible to dress the periphery of a grinding wheel, such as the grinding wheel 38, to the particular form shown and the periphery of which is complementary in section to the shape of the projection 96 of the template 9!! and as best shown in Fig. 6. It will be understood that in such case the periphery -1" the grinding wheel simultaneously engages the flanks between two adjacent turns of the threads on the workpiece. As far as I am aware there is no commercially practical grinding wheel dressing fixture that would permit the periphery of the grinding wheel to be dressed so as to enable it to simultaneously grind the flanks between three or more adjacent turns of the thread on a workpiece. However, the mechanism provided in accordance with the present invention permits such dressing of the periphery of the grinding wheel to be readily accomplished. In such event ail that is necessary is to replace the template illustrated in Figs. I to 6, inclusive, with a'template member of the general type illustrated in 7 which is identical in all respects to the template member fill shown in Fig. 5 except that the operative edge of the template member is shaped to provide a plurality of projections [29 conforming in shape and in spacing to the crosssectional shape and spacing of a plurality of ribs re o d to be formed on the periphery of the 5 wheel to simultaneously grind the sides of. plurality of threads on a piece of work. As will appreciated the same movements of the block on the upper surface of the slide '28 to the tracer point 90 to follow the contour of the operative edge of this modified form of template member will cause exactly the same movements of the diamond [[32 over the face or "phery of the associated grinding wheel to t the desired dressing thereof.

:ill be understood that the main body por- A er the template illustrated in Fig. 7 is idento the main body portion of the template and, accordingly, it is illustrated by the s me number except that such number bears the tter Likewise in Figs. 8, 9 and If) the portion of' the template is identical to that illustrated in Figs. 6 and 7 and, accordingly, in 8 it is illustrated by the numeral 9%, in Fig. by the numeral 900 and in Fig. 10 by the numeral The only difference between all of these constructions is in the shape of the ative edge of the template. In Fig. 8 the o crative edge is formed to provide two projecti as :22 arranged in spaced relation with respect .ch other and with the angularity of one face different from the angularity of the other. Such form of template may be employed in connection with the dressing of grinding wheels adapted to grind threads of special formation such as those, for instance, designed to withstand a high decree of thrust in one direction only, or for other purposes. In Fig. 9 the operative face of the template is provided with three projections I24 arranged in. spaced relation with respect to each other. In this case the projections are of partially circular shape in plan. View as illustrated. The types of projections illustrated in Fig. 9 might be used, for instance, in forming peripheral grooves in a cylindrical workpiece where the grooves each lie in a plane perpendicular to the axis of the workpiece and, accordingly, are truly annular in shape and disposition. In. Fig. 10 a single wide projection I26 is provided on the operative face of the template, the shape of the projectioni2$ being representative of the shape of some groove which it may be desired to form in the periphery of a workpiece for some desired reason.

It will be appreciated that the template members are relatively simple to produce and the operative faces of the same are readily formed into exact complementary relation with respect to the desired shape for the workpiece. In fact it has been found that even in cases where it is desired to grind the surface of a single workpiece to accurately produce a shape of predetermined formation thereon, it is often easier and quicker to provide a template member of the type illustrated and form its operative face or edge into complementary relation with respect to the shape desired, than to attempt to dress the face of the grinding wheel to complementary shape as, for instance, by applying a template thereto and dressing by the trial and error meth- 0d, and the use of the present invention in such case usually results in a much more accurately finished article than in the conventional method mentioned.

Formal changes may be made in the specific embodiment of the invention described without departing from the spirit and substance of the invention, the scope of which is commensurate with the app-ended claims.

What is claimed is: V

i. In a grinding machine including a base having ways thereon, a table movable along said ways and adapted to receive a piece 'of work to be ground thereon, and a grinding wheel arranged in operative relation with respect to said work, the combination of a supporting base carried by said table, an auxiliary supporting member having a planar face supported on. said base and movable with respect thereto about a pivotal axis, means for locking said auxiliary support-.

ing member against relative inbvernent with respect to said first mentioned supporting memher, a template membercarried by said auxiliary supporting member and arranged to be fixed in position with respect thereto, a block having a planar face arranged in contacting relationship with respect to the first mentioned planar face and adapted to be moved thereon in any directio-r1 ,a tracer point fixed with respect to said block. and arranged for engagement with the operativeface of said template member, and a pointed grinding wheel dressing element also carried by said block in spaced relation with respect to said tracer point and arranged with its apex in a line perpendicular to the planar face of said block and passing through the apex of said tracer point, said planar faces being arranged in parallel relation. with respect to the axis of said grinding wheel, and said grinding wheel dressing element being located at a dis-' tance from said faces substantially equal to the distance between the plane of said faces and the axis of said grinding wheel measured in a direction perpendicular to the extended plane of said faces.

2. In a grinding machine including a frame having ways thereon, a table movable along said ways, centers carried by said table for the purpose of supporting a piece of work therebetween, a grinding wheel supported by said frame in operative relation to a piece or" work carried between said centers, and means for moving said grinding wheel bodily toward and away from a line connecting said centers, the combination of a base device carried by said table, a slide mounted on said base device and movabie linearly with respect thereto toward and from the axial line of said grinding wheel, a template member fixed with respect to said slide and having an operative face shaped to conform exactly with the shape desired on the periphery of the grindmg wheel, a block member supported by said slide for movement in any direction in a planeparallel to the axis of said grinding wheel, a tracer point carried by said block member and engageable with the operative face of said template member, a pointed grinding wheel dressing element carried by said block member for move 5 ment therewith in a plane approximately including the axis of said grinding wheel and with its apex included in a line perpendicular to said plane and also including the apex of said tracer point, the construction and arrangement being such that said slide may be adjusted on said supporting device to so position the operative edge of said template member that each time said grinding wheel is drawn towards the work carried between said centers and is dressed by said dressing element, the periphery of said grinding wheel will be located at the predetermined distance from the line connecting said centers required for finish grinding any one of a plurality of identical workpieces successively received be- 10 tween said centers, to a predetermined size.

RALPH E. CROSS.

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