US2317411A - Dressing mechanism - Google Patents

Description

April 27, 1943. H. N. sEYFERTH DRESSING MECHANISM 4 Sheets-Sheet l Filed Nov. 8, 1941 ffaro April 27, 1943. H. N. sEYFERTH DRESSING MECHANISM Filed Nov. 8, 1941 4 Sheets-Sheet 2 fizzle/dor www YW April 27, 1943. H. N. SEYFERTH 21,317,411

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H. N. SEYFERTH DRESSING MECHANISM Filed NOV. 8, 1941 4 Sheets-Sheet 4 Patented Apr. 27, 1943 DRESSING NIECHANISM Harold N. Seyferth, East Detroit, Mich., assignor to Ex-Cell-O Corporation, Detroit, Mich., a corporation of Michigan Application November 8, 1941, Serial No. 418,299

(Cl. 12S-11) 19 Claims.

The present invention relates to improvements in dressing mechanisms for grinding wheels.

One of the objects of the present invention is to provide a novel dressing mechanism having at least one dressing tool arranged to describe a path of movement in one direction for dressing one ank of a grinding rib, and to describe a similar path of movement displaced from said first-mentioned path in the return direction to dress the other flank of the rib.

Another object is to provide a new and improved dressing mechanism having a dressing tool arranged to describe similar but displaced paths of movements in opposite directions, and having means for adjusting the degree of displacement of said paths so as to obtain ribs of different widths but with the same included angle.

A further object is to provide a novel dressing mechanism of the foregoing character having a reversible drive, including a follower mechanism arranged for -adjustment as an incident to reversal of the drive to effect clearance between the tool and the grinding wheel during a portion of the dressing movement in each direction.

Still another object is to provide a new and improved dressing mechanism having a dressing tool, and reversible drive means effective to translate the dressing tool in one direction through a cutting path and upon reversal at any point in said path to retract said tool from engagement with the previously dressed surface.

Further objects and advantages will become apparent as the description proceeds.

In the accompanying drawings:

Figure 1 is a plan view, with the cover removed,

of a dressing mechanism embodying the features of my invention.

Fig. 2 is an end elevational view of the dressing mechanism.

Fig. 3 is a vertical sectional view taken along line 3 3 of Fig. 2.

Fig. 4 is a vertical sectional view taken along line 4-4 of Fig. 3.

Fig. 5 is ahorizontal sectional view taken along line 5 5 of Fig. 3.

Fig. 6 is a fragmentary plan view taken substantially along line E-G'of Fig. 3.

Fig. 7 is a diagrammatic representation illustrating the path of movement of the dressing tool under one condition of adjustment.

Fig. 8 is -a diagrammatic representation illustrating the path of movement of the dressing tool under another condition of adjustment.

Fig. 9 is a diagrammatic representation illustrating the path of movement of the dressing mechanism under still another condition of operation.

Fig. 10 is a fragmentary plan view of a modied form of dressing mechanism comprising two tools for dressing opposite iianks of a grinding Wheel rib.

Fig. 11 is a diagrammatic representation illustrating the paths of movement of the dressing .tools in the form of Fig. 10.

While the invention is susceptible of various modifications and alternative constructions, 1 have shown in the drawings and will herein describe in detail the preferred embodiment, but it is to be understood that I do not thereby intend to limit the invention to the specic form disclosed, but intend to cover all modifications and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims.

The dressing mechanism constituting the exemplary embodiment of the invention comprises a main body or housing I adapted to be mounted upon a suitable support in appropriate relation to a grinding wheel 2. In the present instance, the housing I is hollow, and has a lower section 3 formed with a circular mounting flange 4 rotatably secured for angular adjustment within a yoke 5 on a dresser slide 6 adjustable toward and from the grinding wheel 2. A top section 1 is bolted to the section 3, and has an access opening 8 normally closed by a removable cover plate 9.

Enclosed in the housing I is a composite slide assembly, consisting of a slide or carriage I3 movable in a. direction generally parallel to the axis of the grinding wheel 2, and a tool slide I4 mounted on the slide I3 for movement therewith and also for movement thereon in a direction generally perpendicular to the Wheel axis. The slide I4 projects freely through an opening I5 in one end wall of the housing I, and carries a tool holder I6 formed with a socket II to receive a single point dressing tool I8. By reason of the independent cross movements of the slides I3 and I4, the dressing tool I8 is given a. resultant movement adapted to produce the desired cutting contour on the grinding wheel 2.

The carriage It is supported for reciprocation within the housing I by means of suitable ball bearings I 9, and serves to support most of the actuating parts of the dressing mechanism. Journaled in ball bearings 20 in the carriage I3 is a vertical cam shaft 2l. A plurality of cams 22, 23 and 24 are secured in axially spaced relation to the shaft 2i for rotation therewith. The cam 22 controls the reciprocation of the carriage I3; the cam 2g controls the reciprocation of the slide Iii on the carriage I3; and the'cam 24 controls the cycle of dressing operation.

Any suitable means may be provided for driving the shaft 2i through a predetermined movement. In the present instance, this means comprises a worm wheel 25 xed on the shaft 2I intermediate the bearings 2li and meshing with a Worm 26, The worm 26 in turn is fixed on a drive shaft 21 suitably Journaled in bearings 28 and 29 within the carriage I3 and connected at one end to a flexible shaft 3| driven by a reversible electric motor (not shown). The motor is controlled by a switch 33 suitably mounted within the housing I.

The cam 22 coacts with a cam follower 34Y which is pivotally mounted intermediate its ends on a pin.35 within a sleeve 36 supported in and extending through a bore 31 in one wall of the housing I. The inner end of the follower 34 is formed with a V notch 38. An adjusting screw 39, with a micrometer dial 40, is threaded into the outer end of the sleeve 36, and has a tapered or conical end 4I adapted for engagement in the notch 38 to control the action of the follower upon forward and reverse movements of the cam 22. When the screw 39 is turned into its innermost position to locate the conical end 4I tightly in the notch 38, the follower 34 is secured rigidly in position, i. e., constrained against pivotal movement about the pin 35. Upon loosening the screw 39 to a predetermined extent, as indicated by the micrometer 40, lost motion is introduced between the conical end 4I and the notch 38 to permit a limited degree of oscillation of the follower 34. The amount of lost motion, and hence the degree of oscillation, may be adjusted by varying the extent to which the screw 39 is turned out in accordance with the requirements of the dressing operation. Suitable springsl I3, acting on the carriage I3, serve to maintain the cam 22 in operative engagement with the cam follower a conical tip 49 adapted for engagement in the socket 41. When the tip 49 is in full tight engagement with the socket 41, it constrains the follower 45 against swinging movement about the pin 46. Upon loosening the screw 48, lost motion is introduced between the conical tip 49 and the socket 41, and permits swinging or oscillatory movement of the follower 45 upon reversal of rotation of the cam 23. The screw 48 is loosened .more or less, depending upon the desired degree of oscillation. Suitable springs I4*i act on the slide I4 to maintain the follower 45 in operative association with the ca m 23.

The cam 24 acts through a lever 58 pivoted on the carriage I3 and arranged to actuate the switch 33. In the present instance, the cam has an arcuate projection 5I arranged to contact the lever after slightly less than one revolution in opposite directions. Upon actuating the electric drive, controlled in part by the switch 33, to initiate the dressing cycle, a rotary drive will be imparted to the cam shaft 2|. Upon rotation of the shaft 2I through slightly less than one complete revolution, the cam projection 5I will engage the lever 50 to actuate the switch 33, and thereby reverse the drive. After reverse rotation through the same degree of revolution, the cam projection 5I will again engage the lever 50 to actuate the switch 33 and to therebystop the drive and terminate the cycle.

The dressing mechanism is adapted to dress a wide variety of grinding wheel forms, but has particular applicability to the dressing of truncated thread forms, auch for example as illustrated in Figs. 7 and 8. This form comprises a grinding rib 52 in the periphery of the grinding wheel 2 and having sidenanks 83 and 54 Oppositely inclined at any desired included angle. The flanks are joined at their apex by a truncating line or end face 55 parallel to the axis of the grinding wheel.

In operation, ifl the screws 88 and 4l are tightened to lock the cam followers 34 and 45 against oscillation, both slides or carriages I3 and I4 will move exactly as predetermined by the form or contour of the respective cams 22 and 23. The shape of these cams is obviouslyselected to obtain the desired resultant path of movement oi the dressing tool, which path, for illustrative purposes, may define a contour illustrated by the full line O-A-B-C-D-M in Fig. 1. Since the followers 34 and 45 are constrained against oscillation, the path of movement will be the same in both the forward and reverse operations;

To facilitate the dressing of the entire cutting contour of the grinding rib 52 by means of a single dressing tool I8, it is desirable to have the tool cut only on the radially inward movement and to clear the grinding rib on the radially outward movement.

Radial clearance is obtained by releasing the screw 48 to introduce a predetermined amount of lost motion between the socket 41 and the tapered tip 49, and thereby permit oscillation of the ,cam follower 45 between the two extreme positions upon reversal of rotation of the coacting cam 23. Such radial clearance is indicated at 58 in Figs. 8 and 9 and results in retraction of the dressing tool radially on the return movement, as indicated by the path M-M'-D'-C-B'A'O'-O.

Clearance longitudinally of the grinding wheel axis is obtainable by releasing the screw 39 to introduce lost motion between the notch 38 and the tapered end 4I, and thereby permit limited oscillation of the follower 34 between two extreme positions upon reversal of rotation of the coacting cam 22. Such longitudinal clearance is indicated at 51 in Fig. 9, and results in retraction of the dressing tool for the purpose of clearing each ilank on the outward movement. The degree of clearance in each instance is determined by the degree of the lost motion, which in turn may be varied by the extent to which the respective screws 39 and 48 are retracted.

Assuming that both cam followers 34 and 45 are released for oscillatory movement, and assuming further that the dressing cycle is initiated by starting the drive to the shaft 2I, the respective cams 22, 23, 24 will start to rotate in the direction of the arrow (see'Fig. 1). During this rotation, the dressing tool I8 will move along the line O-A (see Fig. 9), then outwardly along the line A--B without contacting the contiguous flank 53, then along the line B-C in the course of which it will contact and dress the truncating line 55 of the grinding rib 52, then radially inwardly along the line C-D to dress the ank 54, and then longitudinally along the line D-M. At the point M, the cam shaft 2| will have completed slightly less than one complete revolution to cause the cam 24 to actuate the switch I3.

Actuation of the switch serves to reverse the drive through the worm 23 and worm wheel 25 to rotate theA cams 22, 23, and 24 in the reverse direction. Thereupon, the dressing tool I8 will describe a path of movement from M to M', then M' to D', then D' to C', and then'C to B' without contacting the previously dressed flank54 and truncating line 55. In the continued return movement, the dressing tool I8 will move along the line B'-A' to dress the opposed flank 53, and then along the lines A- and O'--O back to initial position. At thisl point, the cam 24 will again actuate the switch 33 to interrupt the drive, and thereby terminate the dressing cycle.

It will be noted that the contour of the path of movement of the dressing tool I8 is the same in both directions of operation, but that the respective paths are displaced from each other both radially and longitudinally of the grinding wheel 2 so that in one path the tool will dress one flank from the apex to the root, and in the reverse path the tool will dress the other ilank from the apex to the root. This separation of the reverse paths of movement is obtained by reason of the radial and longitudinal clearances effected through oscillation of the cam followers. By varying the extent of the clearances, the width of the rib can be altered without changing the included angle between the flanks. of various widths can be obtained merely by adjusting the range of oscillation of the cam followers 34 and 45, and upon sufficient adjustment, ribs of V form can be produced.

In the modified form of Figs. l0 and l1 two tools I8a and I8b are arranged respectively to dress the opposite anks 53c and 54a of a grinding rib 52a. The paths of movement described by the tools are illustrated in Fig. 11. Briefly,

stated, during the initial operation of the dressing mechanism in one direction, the tool I8a will dress the flank 53 and the truncating line 55a. During this movement the other tool will describe a path of similar contour, but by reason of the longitudinal and radial clearances will not contact the grinding rib 52a. During the reverse operation of the dressing mechanism, the tool I8b will dress the opposed flank 548, while the tool I8ai will clear the rib. The two tool arrangement is especially suitable for dressing grinding wheel ribs having a relatively small included angle between the flanks.

I claim as my invention:

l. In a dressing mechanism, in combination, a support, a dressing tool holder mounted for movement in forward and reverse directions, and means for moving said holder, said means including a lost motion toggle connection for causing the paths of forward and reverse movement of said holder to be non-coincident.

2. In a dressing mechanism, in combination, a support, a dressing tool holder adapted to support a dressing tool and mounted for movement in forward and reverse directions, means for actuating said holder to translate said dressing tool, and pivotal means adapted to occupy one extreme position during movement of said dressing tool in one direction and another extreme position during movement of said dressing tool in the other direction, whereby to cause said tool to describe spaced paths of movement.

3. In a dressing mechanism, in combination,

a support, a holder adapted to carry a dressing' tool and being mounted in said support for reversible movement, and means including a cam coacting with said holder to move said dressing tool through a path of predetermined contour, said last-mentioned means including a pivotal cam follower adapted for reverse oscillation into opposite extreme positions upon reverse move- Consequently, truncated rib forms ment of said cam, and means selectively available for locking said follower against pivotal -movement or varying the degree of said pivotal movement.

4. In a dressing mechanism, in combination, a body housing, a supporting member mounted for rectilinear movement within said housing, a tool holder mounted on said supporting member for movement therewith and for independent movement in a direction perpendicular thereto, a rotary cam mounted on said member, a pivotal cam follower mounted on said holder and coacting with said cam, said follower being automatically reversible upon reverse movement of said cam whereby to adjust the relationship between said cam and said holder, and a dressing'tool carried by said holder.

5. In a dressing mechanism, in combination. a main body, a first slide mounted on said body for movement in one direction, a second slide mounted on said first-mentioned slide for movement in an inclined direction andv carrying a dressing tool, and reversible drive means mounted on said first 'slide for reciprocating said second slide and including a lost motion drive connection with said second slide for causing said dressing tool to describe a predetermined cutting path in one direction of movement and on reverse movement to occupy a retracted position.

6. In a dressing mechanism, in combination, a housing, a support in said housing, a rotary reversible drive cam mounted on said support. a tool slide mounted on said support for reciprocation radially of said cam, a pivotal follower mounted on said slide and coacting at its free end with said cam, a tapered recess in said follower, a tapered detent adjustable on said slide for engagement in said recess to provide a lost motion resulting in oscillation of said follower into diil'erent angular relations to the radius upon reverse movement of said cam, whereby to advance or retract said slide relative to said cam, and a dressing tool mounted for movement with said slide.

7. In a dressing mechanism, in combination, a support, a first slide mounted on said support for rectilinear movement in one direction, a second slide mounted on said first slide for rectilinear movement in an inclined direction, a dressing tool supported by said second slide, reversible drive means for reciprocating said rstmentioned slide, reversible drive means for reciprocating said second-mentioned slide on said rst-mentioned slide in timed relation to said first-mentioned slide, whereby to cause said dressing tool to describe a resultant path, each of said drive means including a lost motion connection automatically operable as an incident t0 reversal to adjust the position of the associated slide in relation to the associated drive means whereby said tool is caused to move in a predetermined path in one direction and in a different path in the reverse direction.

8. In a dressing mechanism, in combination, a housing, a slide mounted in said housing for reversible movement. a dressing tool carried by said slide, a rotary drive cam carried by said slide, an oscillatory cam follower mounted in said housing and coacting with said rotary cam, and spring means acting on said slide to maintain said cam in operative engagement with said follower, said follower being reversibly movable as an incident to reversal of said cam whereby to adjust the position of said slide in relation to the angular phase of said cam.

9. In a dressing mechanism, in combination, a

housing, a slide mounted within said housing forY reverse movement, a dressing tool operatively associated with said slide for actuation thereby, and means including a rotary cam and coacting cam follower for reciprocating said slide, said cam -follower being pivotal in opposite directions as an incident to reversal of said cam whereby to vary the center distance between said cam and the pivot of said follower.

10. In a dressing mechanism, in combination,- a housing, a slide mounted for reverse movement on said housing, a dressing tool operatively associated with said slide for actuation thereby in reverse directions, a rotary cam mounted on said slide, a cam follower pivotally mounted intermediate its ends on said .housing and coacting at one end with said cam, spring means acting to maintain said cam in operative engagement with said follower, the other end of said follower being formed with a tapered recess, and a screw adjustably supported in said housing and having a complementa] tapered end adapted to project adjustably into said recess whereby to permit a limited degree of oscillation of said follower upon reversal of said cam.

11. In a dressing mechanism, in combination, a housing,a main slide suspended in said housing for rectilinear reciprocation, a second slide supported on said main slide for movement therewith and for reciprocation thereon in a generally transverse direction, a dressing tool carried by.

said second slide, a shaft journaled in said main slide, a worm and worm wheel drive for rotating said shaft in reverse directions, means including a rotary cam on said shaft and a coacting follower in said housing for reciprocating said main slide in a back and forth movement upon rotation of said shaft, and means including a cam on said shaft and a coacting follower on said second silde for reciprocating said second slide in timed relation to the reciprocation of said main slide.

12. In a dressing mechanism, in combination, a support, a dressing tool holder mounted for movement in forward and reverse directions and carrying two spaced dressing tools, and means for moving said holder, said means including a lost motion toggle connection for causing the paths of forward and reverse movement of said holder to be non-coincident.

13. In a dressing mechanism, in combination, a support, a tool holder carrying two oppositely disposed tools in ilxed relationship with respect to each other and adapted for dressing opposite sides of the periphery of a rotary grinding wheel, a slide assembly for supporting said holder for movement in a predetermined resultant path, and means for actuating said slides in reverse directions and including lost motion means operable in one direction of movement to move one of said tools through a cutting path while maintaining the other of said tools in a retracted position and in the other direction of movement to move the other of said tools in a cutting path while maintaining the first-mentioned tool in a retracted position.

14. In a dressing mechanism, in combination, a support, a tool holder mounted for reverse movement on said support and carrying a single dressing tool for dressing opposite side flanks of the periphery of a cutting rib on a grinding wheel, and means for actuating said tool and including lost motion means automatically oper-A able as an incident to reversal of movement of said tool, whereby to cause said tool in one direction of movement to clear one of said flanks and to dress the other of said flanks and in the other direction of movement to clear said other flank and to dress said first-mentioned flank.

15. In a dressing mechanism, in combination, a support, a tool holder mounted for reverse movement on said support and carrying a single dressing tool for dressing opposite side flanks of the periphery of a cutting rib on a grinding wheel, means for actuating said tool and including lost motion meansautomatically operable as an incident to reversal of movement of said tool, whereby to cause said tool in one direction of movement to clear one of said flanks and to dress theother of' said flanks and in the other direction i' movement to clear said other flank and to dress said first-mentioned flank, and means for adjusting the degree of lost motion whereby to adjust the extent of said clearance.

16. In a dressing mechanism, in combination, a support, a tool holder carrying a dressing tool for dressing opposite flanks of a tapered rib on the periphery of a grinding wheel, and means for actuating said tool'successively in opposite directions to describe a predetermined path of movement in one direction and a like path but spaced from said first mentioned path in a reverse direction respectively to dress the opposite flanks.

17. In a dressing mechanism, in combi-nation, a support, a tool holder mounted on said support and carrying a dressing tool, means for reversibly driving said dressing tool through a path which extends across the opposite flanks of a grinding wheel to be dressed, said driving means including lost motion means effective at each reversal of tool movement to cause the tool when moving in one direction to dress one flank and clear the opposite flank, and when moving in the opposite direction to clear said one flank and dress said opposite flank.

18. In a dressing mechanism, in combination, a support, a first slide mounted thereon for movement in one direction, a second slide mounted on said first slide for movement in an inclined direction, a dressing tool carried by said second slide, reversible driving means for reciprocating both slides in their respective directions whereby the path described by said tool willA be the resultant of both slide movements, said drive means including a lost motion drive connection to each slide for causing the tool to describe different paths as it moves in opposite directions.

19. In a dressing mechanism, in combination, a support, a first slide mounted thereon for movement in one direction, a second slide mounted on said first slide for movement in an inclined direction, a dressing tool carried by said second slide, reversible drive means for reciprocating both slides in their respective directions whereby the path described by said tool will be the resultant of both slide movements, said drive means including a lost motion drive connection to each slide for causing the tool to describe different paths as it moves in opposite directions, and means for independently adjusting the extent of lost motion in the connection to each slide.

HAROLD N. SEYFERTH.

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