US2601456A - Forming means for profile grinding wheels - Google Patents

Description

June 24,1952 Q B, A, PORTER 2,601,456

FORMING MEANS FOR PROFILE GRINDING WHEELS June 24, 1952 C, B, A, PORTER 2,601,456

FORMING MEANS FOR PROFILE GRINDING WHEELS Filed May 2, 1949 2 SHEETS-SHEET 2 INVENTOR 6 CHARLES BENJAMIN ALBERT PoRTE ATTYS Patentecl June 24, 1952 FORMING MEANS FOR PROFILE GR-INDING WHEELS Charles Benjamin Albert Porter, Preston, Yeovil, England, assigner to Harold Stuart Hallewell, Hayes, Middlesex, England Application May 2, 1949, Serial No. 90,951 In Great Britain May 3, 1948 6 Claims.

This invention relates to apparatus for use in forming on a grinding wheel a prolile which is the complement of a profile required to be ground thereby on a tool, die, gauge or other work-piece, by means of a dressing-tool point operated by a pantograph mechanism having a follower member adapted to follow a template. The apparatus to which the invention relates is able to form profiles having portions which are radial with respect to the axis of rotation of the grinding' wheel and which face both right and left; and this ability is provided by arranging for the holder for the dressing tool to rock about an axis which is tangential to the grinding wheel, and for the template-follower member to rock about an axis which is perpendicular to the plane of the template, a linkage supplementary to the pantograph mechanism being provided whereby the dressing-tool holder is constrained to rock in unison with the rocking of the template-follower member. Apparatus of this kind is `described in patent application Serial No. 567,398, of C. B. A. Porter and C. P. Seymour, filed December 9, 1944, (Patent No. 2,469,844).

The dressing tool usually has a radiused tip, and the template-follower member has a working tip which is geometrically similar in section to the section of the tip of the dressing tool, the ratio of the radii of these two tips being equal to the mechanical advantage of the pantograph mechanism. The centre about which the radiused tip of the template-follower member is formed is on the rocking axis of this member. and it is necessary for the dressing tool to be so set that the centre about which its radiused tip is formed-is on the rocking axis of the dressingtool holder.

The object of this invention is to provide means whereby the dressing tool can be located precisely in the desired position in relation to the rocking axis of the dressing-tool holder. The dressing tool is commonly a diamond mounted on 'a conical or wedge-shaped end of a cylindrical steel shank, and it has been discovered that a source of inaccuracy in the Work done by apparatus of the kind hereinbefore referred to is slight eccentricity cf the centre about which the radiused tip of the dressing tool is formed in relation to the axis of the cylindrical shank of the dressing tool.

A preferred embodiment of the invention will be described with reference to the accompanying drawings as applied to apparatus of the design shown diagrammatically in Figure l of the abovementioned patent specification. In the accompanying drawings:

-Figure 1 is a cross section of the dressing-tool holder and of the pantograph arm in which it is mounted, the section being taken in the vertical plane `containing the rocking axis of the holder.

Figure 2 is a section of a detail taken on theI line 2--2 in Figure 1.

Figure 3 is an elevation of part of the dressingtool holder, viewed in the same direction as Figure 1.

Figure 4 is an elevation of a detail as viewed from the right-hand side of Figure 1.

Figures 5, 6 and 7 are explanatory diagrams.

Figure 8 is a perspective diagrammatic View of the complete pantograph apparatus, suitable for use with asurface grinder of conventional type.

The apparatus shown in Fig. 8 includes a rectangular base plate 60 engaged by the magnetic chuck 6I of the surface grinder and has a depending flange 62 at one edge, which serves to locate the base square with respect to the grinder.

A bracket 63 rigid with the base carries a board 64 to which is xed a template 65 lying in a vertical plane parallel to the axis of the grinding wheel 66. The pantograph linkage includes a more or less horizontal long link 61 pivoted on a bearing pin 68 mounted on the base 60. A short more or less vertical link 69 is also pivoted on the pin 68. An arm 'III parallel to the link 69 is pivoted to the free end of the link 61 and carries a template-follower 'II at its upper end. A second arm II parallel to the link 61 is connected between the upper end of the link 69 and a point on the template-follower arm 10. The arm I I carries a Wheel-dressing tool I8.

The template-follower II is formed by a horizontal pin journalled in the upper end of the arm IIJ. To the end of the pin II is fitted a sectorshaped blade 12.

The dressing tool is carried by a horizontal shaft I0 journalled in the arm II, the arrangement being such that the diamond tool I8 can be set below the wheel 66.

The template-follower pin 'II and the diamondholder shaft I0 are connected for rocking in unison under control of a hand Wheel '|31 on the pin 1I. The necessary connection consists of a steel belt 39 on pulleys 4I and I4 respectively xed on the shaft In and rotatable on a pivot pin 'I5 connecting the arms I I and 10, and a steel belt 'I6 on pulleys I1 and 'IB respectively fixed to the pulley 'I4 and the pin 1I. The belts are pinned to the respective pulleys, by means hereinafter described, so as to prevent slip.

Figures l to 4 show actual preferred constructional forms of certain parts that are shown merely diagrammatically in Figure 8. The dressing-tool holder shaft Ill is mounted in precisionv bearings in the arm I I of the pantograph linkage. the shaft being integral with an extension I2 cranked so as to lie to one side of the shaft axis XX. On the end of the extension I2 is a straight L-section guide way I3 having one face I4 directed towards the shaft axis and the other face I5 perpendicular to this axis and directed away from the shaft. For convenience of description the face I4 is assumed to be horizontal and upwardly directed. Mounted on the guide way I3 is a rectangular slide block I6 having a bore I1 opening at its top face and adapted to receive the shank of the dressing tool I8. This bore lies in a Vertical plane at a slight inclination to the vertical. A grub screw I9 fitted in the bottom of the slide block I6 and accessible through a slot in the bottom of the guide way bears on the bottom end of the dressing tool I8 and enables its height to be adjusted. A screw 2I (Figure 3) fitted in an end of the block I6 engages a flat 22 on the side of the shank of the dressing tool near its bottom end and fixes it in the correct angular position in relation to 'the axis of the bore. A third screw 23 fitted in the back of the block IB engages a neck on the shank of the dressing tool near its upper end and locks Y it rigidly to the block.

The vblock can be .locked to the guide way by means of a screw v24 lying in a vertical plane at an .angle of 45 and passing upwards with clearance through a slot 25 opening into the angle of the guide way I3, the slot extending on each side ofthe 'middle of the length of the guide way. The upper end of the screw 24 is engaged in a tapped hole in the block, and its Yhead bears on a plane facing 26 Vat `the bottom of the slot. j

A `straight two-armed adjusting lever 21 is mounted on a pivot screw 28V fitted vertically to the .dressing-tool holder behind the guide way. The front arm of this lever passes through a horizontal slot 29 in the vertical face I'5 of the guide way and is engaged in a vertical groove 30 in the back of the block I6. The rear arm is held by a compression spring 3I (Figure 2) in engagement with a horizontal micrometer screw 32 lying more or less perpendicular to the length ofthe lever, the spring 3| and the screw 32 being carried by depending parts of the cranked extension I2.

Lateral adjustment of the tip of the dressing tool is effected by slackening the block-locking screw 24, adjusting 'the micrometer screw 32 so as to shift the block, through the agency of the lever 21, laterally as required, and tightening the locking screw 24.

A dial gauge 33 is mounted, with its actuating stem 34 depending vertically and engaging th'e tip of the dressing tool I8, on a rigid arm 35 I extending horizontally from a l.bracket 36 detachably fitted by a dovetail L3.1 (Figure 4) to a facing on top of the pantograph arm I I. A screw 38 locks the bracket.

The dressing-tool holder can be rocked by the agency of the hand wheel 13 acting through the ilexiblesteel belts 16 and 39. In Figure 1 the belt 39fis shown pinned at 4B to the pulley 4I fixed to the lshaft I0. .If when thendressing-tool holder is rocked the dial gauge 33 shows a maximum or a Aminimum .reading as Vthe dressing-tool axis crosses the vertical plane containing the axis X-X, the dressing tool is too high or too low. Figure 5 shows for example the caseY where the dressing tool I8 is set too high. Thecentre about which its radiused tip is formed is denoted by C, and the rocking axis by the cross X. The full lines show the parts in the configuration giving the maximum reading, and the broken lines show a Vcondition when the dressing-.tool axis is out of the said vertical plane. If the .rea-ding of the dial gauge 33 is higher when the `dressing-tool holder is inclined to one side than when it is inclined to the other side, the centre of the dressing-tool tip is offset from the rocking axis of the dressing-tool holder to the side on which the lower reading occurs, as indicated in Figure 6; this error is corrected by means of the micrometer screw 32. When the dressing tool is correctly set, as shown in Figure 1, the dial reading is constant for all attitudes of the dressing-tool holder.

The pantograph arm II is a channel-section member having two parallel side walls 42 and 43 provided respectively with .cylindrical bearing housings 44 and 45 for the dressing-tool holder. The bearing in the housing 44 consists of two single-row ball bearings 4S and 41 capable of taking both radial loads and thrust loads in one direction. These two bearings are placed back to back with their outer races abutting .against a locating ring 49 xed by radial dowels such` as 5I! in the housing 44. The inner races are clamped against a distance piece 5I placed be.- tween them and of such a thickness, in relation to the thickness of the locating ring 49, as to introduce a suitable amount of preloading. The clamping force is provided as follows. The inner race of the bearing 46 abuts against a flange 52 at an end of the shaft I0. A tubular distance piece -53 including the pulley 4I abuts against the inner race of the bearing 41. A nut 54 on .the other end of the shaft I0 applies compression to the distance piece 53 and a like tension to the shaft I0.

The bearing in the housing is of the singlerow deep-groove ball type and is denoted by 55. Its inner race is clamped between the nut 54 and distance piece 53; its outer race is an accurate sliding fit in the housing 45 and is urged towards the dressing tool by -a ring of helical compression springs 56 retained by a bearing cap 51.

This bea-ring assembly provides both the rigidity and the accuracy essential for precision work.

I claim:

1. Apparatus for dressing a grinding wheel and including a base, a template-holder on said base, a pantograph mechanism comprising a parallelogram of arms pivotally mounted. on said `base for movement parallel to the template plane, a template-follower on a rst of said arms, aV dressing-tool holder pivotally mounted on a second of said arms for rocking with respect to said second arm about an axis perpendicular to said plane, a dressing-tool having a shank and a radiused tip, means supporting said dressing tool on said holder with said shank substantially perpendicular to said axis, said supporting means including a first adjusting member for moving said tip in the direction longitudinally of said shank. a second adjusting member operating between said supporting means and said holder for moving said tip transversely both to said axis and also to said direction, and a linear displacement indicator movably mounted on said second arm and having an actuating member displaceable perpendicularly to said axis, said actuating member having a plane end face perpendicularly to its direction of displacement and engageable by said tip.

2. Apparatus for dressing a grinding wheel and including a base, a template-holder having a plane face mounted on said base, a template on said face, a pantograph mechanism comprising a parallelogram of arms pivotally mounted on said base for movement parallel to the template face, a template-follower on a first of said arms, a dressing-tool holder pivotally mounted on a second of said arms for rocking with respect to said second arm about'an axis perpendicular to said plane, a dressing-tool having a shank and ,a

radiused tip, a slide block having a bore receiving said shank, an adjusting screw engaged in said block and cooperating with the end of said shank, means positioned on said block for clamping said shank in said block, said holder including a guideway supporting said block while permitting it to be moved transversely with respect to said axis, micro-adjusting means operating between said block and said holder for displacing said block along said guide way, means positioned on said holder for clamping said block to said guide way, and a linear displacement indicator movably mounted on said second arm and having an actuating member displaceable perpendicularly relatively to said axis, said actuating member having a plane end face perpendicular to its direction of displacement and positioned so as to be engaged by said tip.

3. Apparatus for dressing a grinding wheel, of the type including a dressing tool having a shank and a radiused tip, comprising a base, a template-holder having a plane face mounted on said base, a template on said face, a pantograph mechanism including a parallelogram of arms pivotally mounted on said base for movement parallel to the template face, a template follower on a rst of said arms, a dressing-tool holder pivotally mounted on a second of said arms for rocking with respect to said second arm about an axis perpendicular to said plane, a socket member for receiving said shank to locate said tool with said shank substantially perpendicular to said axis, means on said holder constraining said socket member for movement in a direction perpendicular to said axis and to the longitudinal direction of said shank, iine adjustment means interposed between said socket member and said holder for effecting the said movement of said socket member, and a linear displacement indicator movably mounted on said ,1

second arm and having an actuating member positioned so as to be engaged by said tip and displaceable perpendicularly relatively to said axis.

4. Apparatus for dressing a grinding wheel, comprising a dressing tool holder, a template follower, a reducing pantograph mechanism coupling said holder to said template follower for movements in the same directions therewith, said holder being pivotally mounted on said mechanism for rocking about an axis, a dressing tool having a shank and a radiused tip, means supporting said tool on said holder with said shank substantially perpendicular to said axis, said supporting means including a rst adjusting member bearing on said shank for moving same axially thereof, a second adjusting member operl ating between said supporting means and said holder for moving said shank and tip transversely both to said axis and also to the longitudinal axis of the shank, said follower being pivotally mounted on the pantograph mechanism about an axis parallel to that of the said rocking axis, said follower being operably connected to said tool holder so as to rock in synchronism therewith, and a linear displacement indicator movably mounted on an arm of said pantograph mechanism and having an actuating member displaceable perpendicularly relatively to said axis, said actuating member having a plane end face perpendicular to its direction of displacement and positioned so as to be engaged by said tip.

5. Apparatus for dressing a grinding wheel, comprising a dressing tool holder, a template follower, a reducing pantograph mechanism coupling said holder to said template follower for movements in the same directions therewith, said holder being pivotally mounted on said mechanism for rocking about an axis, a dressing tool having a shank and a radiused tip, a slide block having a bore receiving said shank, an adjusting screw engaged in said block and cooperating with the end of said shank, means on said block for clamping said shank in said block, said holder including a guideway supporting said block while permitting it to be moved transversely with respect to said axis, micro-adjusting means operating between said block and said holder for displacing said block along said guideway, means on said holder for clamping said block to said guideway, said follower being pivotally mounted on the pantograph mechanism about an axis parallel to that of said rocking axis, said follower being operably connected to said tool holder so as to rock in synchronism therewith, and a linear displacement indicator movably mounted on said pantograph mechanism and having an actuating member displaceable perpendicularly relatively to said axis, said actuating member having a plane end face perpendicular to its direction of displacement and positioned so as to be engaged by said tip.

6. Apparatus for dressing a grinding wheel of the type including a dressing tool having a shank and a radiused tip, comprising a dressing tool holder, a template follower, a reducing pantograph coupling said holder to said template follower for movements in the same directions therewith, said holder being pivotally mounted on said mechanism for rocking about an axis, a socket member for receiving said shank to locate said tool with said shank substantially perpendicular to said axis, means on said holder constraining said socket member for movement in a direction perpendicular to said axis and to the longitudinal direction of said shank, ne adjustment means interposed between said socket member and said holder for effecting the said movement of said socket member, said follower being pivotally mounted on the pantograph mechanism about an axis parallel to that of said rocking axis, said follower being operably connected to said tool holder so as to rock in synchronism therewith, and a linear displacement indicator movably mounted on said mechanism substantially in alignment with the rocking axis and having an actuating member positioned so as to be engaged by said tip and displaceable perpendicularly relatively to said axis.

CHARLES BENJAMIN ALBERT PORTER.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,463,033 Beckett July 24, 1923 1,326,219 Parker Oct. 6, 1931 2,038,455 Studer Apr. 21, 1936 2,127,614 Parker Aug. 23, 1938 2,234,539 Cooke Mar. 11, 1941 2,355,020 Turrettini Aug. 1, 1944 2,395,598 Weaver Feb. 26, 1946 2,452,509 Victory Oct. 26, 1948 FOREIGN PATENTS Number Country Date 334,558 Great Britain Sept. 5, 1930 442,156 Great Britain Feb. 3, 1936

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