US3870030A

US3870030A - Grinding wheel dresser

Info

Publication number: US3870030A
Application number: US412709A
Authority: US
Inventors: Phillip A Sollami
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-11-05
Filing date: 1973-11-05
Publication date: 1975-03-11
Anticipated expiration: 1992-03-11

Abstract

Apparatus for dressing a grinding wheel includes a bit holder carriage which is reciprocably driven to move a bit across the working face of the wheel, the bit being carried by a member which is rotated in the holder after every other traverse of the wheel thereby changing the working edge of the bit and advancing it toward the wheel.

Description

United States Patent 11 1 Sollami 1 Mar. 11, 1975 GRINDING WHEELDRESSER 2,862,492 12/1958 Bruce 125/11 N 2,909,006 10 1959 B1 d 125 11 N X [76] Inventor: Phillip A. Sollami, 438 Sherman $1., I

Downers Grove 111 0515 FOREIGN PATENTS OR APPLICATIONS Filed Nov 5 1973 581,487 8/1959 Canada 125/11 PH [21] Appl. No.1 412,709 Primary E.raminerHarold D. Whitehead Attorney, Agent, or FirmEdmond T. Patnaude [52] US. Cl ..125/1l TP 151 1111. C1 B24b 53/08 [571 3 158] Field of Search 125/11 R, 11 N, 11 TP, Apparatus for dressmg a grmdmg Wheel Includes a bit 25 1 p 1 1 CC holder carriage which is reciprocably driven to move a bit across the working face of the wheel, the bit being 5 References Cited carried by a member which is rotated in the holder UNITED STATES PATENTS after every other traverse 0f the wheel thereby changing the working edge of the bit and advancing it to- 2,611,356 9/1952 Flygare 125/11 TP Ward the Wheel 2,630,109 3/1953 Bruce 125/11 N 2,648,171 8/1953 H111 125/11 N 8 Claims, 4 Drawing Figures GRINDING WHEEL DRESSER The present invention generally relates to the art of dressing grinding wheels, and it relates more particularly to a new and improved machine for automatically dressing the working surface of the grinding wheel to a predetermined contour.

Apparatus which automatically dresses a grinding wheel is not basically new, but the prior art wheel dressers have been expensive to manufacture and maintain, require a time consuming set up operation, require relatively skilled operators, and require frequent replacement of the dressing bit. There is, therefore, a need for a better wheel dresser which is stable in operation and avoids excessive wear on the dressing bit, which is relatively inexpensive to manufacture, and which can be used by relatively unskilled operators.

Therefore, a principal object of the present invention is to provide new and improved apparatus for dressing the working surfaceof a grinding wheel to a desired contour.

Another object of this invention is to provide a new and improved mechanism for converting rotary motion to reciprocatory motion.

A further object of this invention is to provide a new and improved feed mechanism for automatically feeding and rotating a dressing bit a preset amount.

SUMMARY OF THE INVENTION Briefly, the above and further objects may be realized in accordance with a preferred embodiment of the present invention by providing an electric motor driven translatory mechanism carrying a longitudinally movable bit holder which follows the contour of a template and which is automatically rotated and advanced a predetermined amount after every other pass across the working surface of a grinding wheel being dressed.

BRIEF DESCRIPTION OF THE DRAWINGS Further objects and advantages and a better understanding of the present invention can be had by refer ence to the following detailed description. wherein:

FIG. 1 is an elevational view of a grinding wheel dresser embodying the present invention;

FIG. 2 is a vertical section of the machine of FIG. 1 taken along the line 202 thereof;

FIG. 3 is another sectional view taken along the line 3-3 of FIG. I; and

FIG. 4 is a sectional view taken along the line 44 of FIG. I particularly showing the automatic bit feed or advance mechanism.

DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawings and particularly to FIGS. 1 and 2 thereof, awheel dressing machine includes a base plate 11 suitably mounted in fixed relationship with respect to a grinding wheel 12 to be dressed. A mounting plate 13 is fixed to and extends upwardly from the base plate 11 to support two sets of

pillow blocks

15 and 16 respectively mounting a pair of roller or slide bushings 1-7 and 18. A guide rod 21 is slidably supported in the lower bushings 18 in precise parallel relationship with the upper rod 21.. The bushings l7 and 18 are preferably super ball bushings manu factured by Thomson Industries, Inc.. wherein preload on the rods is proportional to the compressive force exerted on the bushings by the pillow blocks. The

blocks

15 and 16 arethus held together by a plurality of set screws 23 which are used to adjust thecompressive force on the

bushings

17 and 18 and thus preload on the guide rods.

A tool holder carriage 25 includes a tubular portion 26 from which a pair of spaced apart arms 27 "and 28 extend in a rearward direction through a pair of

horizontal slots

29 and 30 in the'mounting plate 13. The

rods

21 and 22 extend through suitable holes in the

arms

27 and 28 and are fixed thereto by any suitable means so as to be carried by and to move in unison with the

rods

21 and 22. A drive member 33 having a rearwardly facing drive channel 34 is secured by bolts to the rear faces of the

arms

27 and 28 and a roller 35 is disposed in the channel 34. The roller 35 is connected by a threaded stud 36 and a nut 37 to a crank arm 38 which is rotatably driven by the output shaft 39 of an electric motor and gear reduction unit 40. As thus far described it may be seen that energizing the drive motor rotates the crank arm 38 and the roller 35 to reciprocably drive the bit holder in a horizontal direction with the

rods

21 and 22 reciprocating back and forth in the

bushings

17 and 18.

Referring particularly to FIG. 3 it may be seen that the forward portion 26 of the tool holder is generally tubular and has an axial bore therein having a lower portion 43 and an upper portion 44 of reduced diameter. A sliding fit is provided between a cylindrical rod 45 and the bore portion 43 in which it is located. The upper portion of an axial bore 46 provided in the rod 45 is threaded to receive the threaded shank 47 of an advance screw having a cylindrical guide portion 48 at the top. The guide portion 48 is slidably received in the upper bore portion 44, and a coil spring 51 is compressed between the upper end of the advance screw and a disc 52 held in place in the upper end ofthe bore portion 44 on a rocker pin 53. The spring 51 thus biases the advance screw and the rod 45 to which it is connected in a downward direction relative to the bit holder.

In order to cause the advance screw and rod to follow a predetermined contour or pattern as the bit holder reciprocates back and forth in the

bushings

17 and 18, a template follower includes a follower pin 56 having an internally threaded body portion 57 attached to the guide portion 48 by means of a socket head screw 58 threadedly received in the body portion 57. A ball bearing roller 59 is mounted on the body portion 57 and held in place by a snap ring 60 and rides in a vertical slot 62 milled in the wall of the tool holder tube 26 to permit up and down movement of the template follower while preventing roatation of the advance screw in the bit holder. As best shown in FIGS. 1 and 2 the follower sleeve 56 rides on the upper edge 63 of a tem plate plate 64 fastened to the mounting block 65 by a plurality of screws 66. The upper edge 63 of the template is provided with the desired cross-sectional contour of the wheel to be dressed. The template 64 can, of course, be readily replaced with others having different contours or profiles. A pair of adjustment screws 67 are threadedly received in the lip of the block 65 for adjustment of the template in the vertical plane.

A wheel dressing bit 68 having a diamond or other cutting tip 69 secured in the lower end thereof is supported in the lower end of the rod 45 and held firmly in place therein by means of a set screw 70 threadedly received in a knurled collar 73 slipped or sweated onto the lower end of the rod 45. Another collar 71 is threaded onto the lower end of the bit holder portion 26 and has an internal groove receiving a scraper ring 72 which is slightly compressed against the rod 45 to prevent spurious rotation thereof and to provide a protectiveseal for the interengaging sliding surfaces of the rod 45 and the bore 43.

i In order to advance the dressing bit an adjustable predetermined amount after every other tranverse of the wheel, an advance lever 75 is pivotally carried on a pintle 81 by a split ring 76 mounted in a pair of slots 77' and 78 in the tubular portion 26. The ring 76 has an arcuate innersurface 79 which rides on the CD. of the rod 45, an the advance lever 75 extends through a slot 80 in the ring 76 for driving engagement with the rod 45 as best shown in FIG.,4. The inner end 83 of the lever 75 is cut on a bias so as to drivingly engage the rod 45 when the lever is pivoted in a clockwise direction as shown in FIG. 4. Near the end of its leftward stroke as shown in FIGS. 1 and 4, the bit holder carries the lever 75 into engagement with a screw 85 adjustably mounted by a bracket 86 to the plate 13. The lever 75 is thus pivoted in the clockwise direction causing the end 83 to engage and lock against the rod 45. Further movement of the carriage causes the ring 76 to rotate and the rod 45 to rotate therewith relative to the advance screw 47 which is prevented from rotating by the roller 59 disposed in the slot 62, whereby the rod 45 is screwed downwardly on the advance screw to advance the dresser bit 69 toward the axis of rotation of the grinding wheel 12 and to rotate the bit 69 a small predetermined amount. The distance through which the bit is advanced and the angle through which it is rotated is controlled by the distance between the end of the screw 85 and the end of the stroke of the bit holder and is adjustable by varying the position of the screw 85 in the bracket 86. As the bit holder moves back in the opposite direction during the succeeding stroke to carry the lever 75 away from the screw 85, the ring 76 and the lever 75 are returned to the illustrated cocked position by means ofa coil spring 88 stretched between apost 89 on the ring 76 and a stud 90 on the bit holder 26. At this time the inner end 83 of the lever 75 pivots away from and slides loosely across the surface of the rod 45 which is prevented from rotating by the scraper ring'72 and the relatively tight fit between the mating threads on the advance screw 47 and the rod 45.

If desired a second advance lever may be carried by the ring 76 at a location opposite the lever 75 and a second screw and bracket is mounted at the right side of plate 13 as viewed in FIG. 1 to advance the bit at the end of each stroke of the carriage ratherthan on every other stroke.

One problem commonly encountered with wheel dressers is that the abrasive dust removed from the wheel by the dressing bit finds its way into the moving parts of the machine. To shield the moving parts of the machine from this dust, a housing, partially shown at 93, encloses the parts of the machine between the plates 11 and 13, and caps (not shown) mounted to the housing are positioned over both ends of the

rods

21 and 22. Adjacent to a horizontal slot 94 in the base plate 11 in which the bit holder reciprocates, a pair of

undercut guide pieces

95 and 96 are mounted to the plate and a rectangular dust shield 97 is slidable therein.

' The shield may conveniently be formed of plastic and is provided with a hole 98 through which the lower cy-" lindrical portion of the bit holder tightly extends. The shield 97 thus slides back and forth in the channel formed by the

strips

95 and 96 and the bottom surface of the plate 11 to prevent foreign matter from entering the housing 93.

OPERATION In use, the machine 10 is mounted directly above the grinding wheel 12 to be dressed with the bit 69 located directly over the axis of the rotation of the wheel. The proper template 64 is mounted in place and the knurled collar 73 is rotated to lower the bit into near engagement with the grinding wheel. With the wheel rotating at normal speed, the motor 40 is then started to cause the bit to reciprocate back and forth across the working surface of the wheel. Near the end of each leftward stroke the rod 45 is rotated a small preset amount by the lever to advance the bit downwardly a cone sponding amount and also to rotate the bit. As a result of the intermittent rotation of the bit and the fact that it cuts first in one direction and then in the other direction, the entire surface of the bit is used thereby providing extemely long bit life. Moreover, the substantial spacing between the bushing 17 and 18 and between the

rods

21 and 22 maintains the bit holder in precise alignment so that no uncontrolled movement of the brittle bit with a consequent fracturing thereof occurs.

When a template is to be changed, the tool holder carriage is positioned between the template mounting screws 66, the tool holder is elevated to raise the template follower away from the template, and the template is removed-and replaced. The tool holder is then permitted to move downwardly whereby the follower engages the upper edge of the new template. The tool holder can then be rotated to accommodate the diameter of the new wheel. Also, the template can be adjusted laterally to match the width of the new wheel.

While the present invention has been described in connection with particular embodiments thereof, it will be understood by those skilled in the art that many changes and modifications may be made without departing from the true spirit and scope ofthe present invention. Therefore, it is intended by the appended claims to cover all such changes and modifications which come within the true spirit and scope of this invention.

I claim:

1. Apparatus for use in dressing the peripheral working surface of a grinding wheel to a predetermined contour, comprising a base member adapted to be mounted in fixed rela tionship to the axis of rotation of a grinding wheel to be dressed,

a tool holder carriage,

means mounting said carriage for reciprocable movement along a rectilinear path parallel to said axis of rotation of said grinding wheel,

motor means for driving said carriage back and forth along said path,

a dressing bit holding member carried by said carriage for guided movement in a direction perpendicular to said path,

an advance screw being carried by said carriage and held against rotation relative thereto,

a template mounted to said base member.

a template follower connected to said advance screw.

and

means carried by said bit holder carriage and intermittently operated in response to the reciprocation of said holder relative to said base member for intermittently rotating said bit holding member relative to said advance screw to intermittently advance said bit holding member and to rotate said dressing bit.

2. Apparatus according to claim 1 wherein said tool holder carriage is provided with a bore,

. said dressing bit holding member and said advance screw being disposed in said bore.

3. Apparatus according to claim 2 further comprising spring means mounted between said tool holder carriage and said advance screw for urging said template follower against said template.

4. Apparatus according to claim 2 wherein said means for intermittently rotating said bit holding member comprises a first member mounted to said holder for limited rotational movement,

a drive lever pivotally mounted to said first member with one end adapted to engage and rotate said bit holding member when said lever is pivoted in a first direction only, and

adjustable means carried by said base member for engagement by said lever to pivot said lever in said first direction and to rotate said first member as said lever is moved relative thereto during the reciprocation of said holder.

5. Apparatus according to claim 4 comprising spring means mounted between said holder and said first member for urging said first member in a di rection opposite to the direction of rotation caused by said adjustable means.

6. Apparatus according to claim 1 wherein said means mounting said tool holder comprises a plurality of parallel rods fixedly connected to said tool holder, and

a plurality of sets of bearings slidably supporting said rods.

7. Apparatus according to claim 6 wherein said means for intermittently rotating said bit holding member comprises a first member mounted to said holder for limited rotational movement,

means carried by said base member for engagement by said lever to pivot said lever in said first direction thereby to rotate said bit holding member relative to said advance screw and said bit holder.

8. For use with grinding apparatus the combination comprising a mounting member,

a plurality of sets of slide bearings fixed to said mounting member, the bearings in each set being arranged in mutually aligned relationship with said sets being arranged in mutually parallel relationship a plurality of rods respectively positioned in said sets of bearings,

a tool holder carriage fixed to said rods,

means for reciprocatively driving said carriage and said rods back and forth in said bearings,

said mounting member being provided with at least one opening therethrough,

a portion of said carriage extending through said opening,

a guide channel connected to said carriage and disposed on the side of said member opposite to said rods,

a crank arm having a drive portion slidably disposed in said guide channel, and

motor means drivingly connected to said crank arm.

Claims

1. Apparatus for use in dressing the peripheral working surface of a grinding wheel to a predetermined contour, comprising a base member adapted to be mounted in fixed relationship to the axis of rotation of a grinding wheel to be dressed, a tool holder carriage, means mounting said carriage for reciprocable movement along a rectilinear path parallel to said axis of rotation of said grinding wheel, motor means for driving said carriage back and forth along said path, a dressing bit holding member carried by said carriage for guided movement in a direction perpendicular to said path, an advance screw being carried by said carriage and held against rotation relative thereto, a template mounted to said base member, a template follower connected to said advance screw, and means carried by said bit holder carriage and intermittently operated in response to the reciprocation of said holder relative to said base member for intermittently rotating said bit holding member relative to said advance screw to intermittently advance said bit holding member and to rotate said dressing bit.

2. Apparatus according to claim 1 wherein said tool holder carriage is provided with a bore, said dressing bit holding member and said advance screw being disposed in said bore.

4. Apparatus according to claim 2 wherein said means for intermittently rotating said bit holding member comprises a first member mounted to said holder for limited rotational movement, a drive lever pivotally mounted to said first member with one end adapted to engage and rotate said bit holding member when said lever is pivoted in a first direction only, and adjustable means carried by said base member for engagement by said lever to pivot said lever in said first direction and to rotate said first member as said lever is moved relative thereto during the reciprocation of said holder.

5. Apparatus according to claim 4 comprising spring means mounted between said holder and said first member for urging said first member in a direction opposite to the direction of rotation caused by said adjustable means.

6. Apparatus according to claim 1 wherein said means mounting said tool holder comprises a plurality of parallel rods fixedly connected to said tool holder, and a plurality of sets of bearings slidably supporting said rods.

7. Apparatus according to claim 6 wherein said means for intermitteNtly rotating said bit holding member comprises a first member mounted to said holder for limited rotational movement, a drive lever pivotally mounted to said first member with one end adapted to engage and rotate said bit holding member when said lever is pivoted in a first direction only, and means carried by said base member for engagement by said lever to pivot said lever in said first direction thereby to rotate said bit holding member relative to said advance screw and said bit holder.