US3067732A

US3067732A - Roller-type dressers for grinding wheels

Info

Publication number: US3067732A
Application number: US770404A
Authority: US
Inventors: Harold E Balsiger
Original assignee: Landis Tool Co
Current assignee: Landis Tool Co
Priority date: 1958-10-29
Filing date: 1958-10-29
Publication date: 1962-12-11
Anticipated expiration: 1979-12-11

Description

Dec. 11, 1962 H. E. BALSIGER 3,067,732

ROLLER-TYPE DRESSERS FOR GRINDING WHEELS Filed Oct. 29, 1958 6 Sheets-Sheet 1 LL INVENTOR l HARULD E-BALSIGER BY l Z )1 TTORNEY Dec. 11, 1962 E. BALSIGER 3,067,732

ROLLER-TYPE DRESSERS FOR GRINDING WHEELS Filed (kit. 29, 1958 6 Sheets-Sheet 2 INVENTOR- HAROLD EEALSIGER BYgkM ATTORNE/IY Dec. 11, 1962 H. E. BALSIGER ROLLER-TYPE DRESSERS FOR GRINDING WHEELS 6 Sheets-Sheet 3 Filed Oct. 29, 1958 INVENTOR HAROLD E.BALSI6ER TTORNEY 1962 H. E. BALSIGER 3,067,732

ROLLER-TYPE DRESSERS FOR GRINDING WHEELS Filed Oct. 29, 1958 6 Sheets-Sheet 4 TRAVERSE PATH OFROLLER PERIPHERAL SPEED OF GRINDING WHEEL DRESSING .S'PEZD INVENTOR HAROLD LBALSIGER ATTORNEY Dec. 11, 1962 H. E. BALSIGER 3, 67,

ROLLER-TYPE DRESSERS FOR GRINDING WHEELS Filed Oct. 29, 1958 6 Sheets-Sheet 5 INVENTOR HAROLD anus/can BY/KbM ATTORNEY Dec. 11, 1962 H. E. BALSIGER 3,067,732

ROLLER-TYPE DRESSERS FOR GRINDING WHEELS Filed Oct. 29, 1958- 6 Sheets-Sheet 6 lNVENTOR HAROLD E BALS/GER BY/gxmj TTORNEY United States 3,067,732 Patented Dec. 11, 1962 v 3,067,732 I *RGLLER-TYPE DRESSERS FQR GRINDING WHEELS Harold E. Balsiger, Wayneshoro, Pa, assignor to Landis Tool Company, Waynesboro, Pa.

Filed @et. 29, 1958, Ser. No. 770,404 9 Claims. (Cl. 125-11) This invention relates to apparatus for dressing the operative surfaces of abrasive wheels.

Over a period of years, two types of wheel dressing apparatus have been in general use for dressing abrasive wheel surfaces. By far, the most widely used is the single point diamond which is generally mounted in a suitable holder which, in turn, is supported on a sliding member so that the diamond may be traversed slowly in contact with theoperative face of the abrasive wheel.

A great deal of heat is generated in the diamond of a single diamond dresser during a dressing operation and this causes the diamond to wear more rapidly. Finally, diamond wear has become a greater factor in quality control because of the increasingly finer limits of size and taper demanded by machine users. One pass of a single diamond across a grinding wheel may cause sufficient wear on the diamond to dress a taper greater than tolerance permits. Another disadvantage of a non-rotatable diamond is that it tends to press the metal particles into the wheel and must remove a greater amount of abrasive in order to remove all the metal.

The second type of dressing apparatus, in use to a lesser extent is the abrasive wheel or roller which may have 'a mounting similar to that of the diamond dresser. These abrasive rollers are rotatably mounted so that when they engage a grinding wheel, they are rotated at a relatively high speed. Provision is made in the form of a braking device to cause the roller to travel at a lesser surface speed than that of the grinding wheel and thus provide a relative movement between the two surfaces to effect the dressing action. It is recommended by the producers of these wheels, that in order to obtain a fine finish on the grinding wheel, they should be mounted with the aXis parallel to that of the grinding wheel. If a coarse surface is desired on the wheel, the roller should be set at an angle of not more than 30.

Wheels and rollers having operative surfaces consisting of diamond particles instead of synthetic abrasive grains, have been used for grinding and also for dressing grinding wheels. When used for dressing a grinding wheel, the axis of the dressing wheel or roller is parallel to the axis of :the :grinding wheel. The dressing roller must rotate at a different surface speed from that of the grinding wheel and, therefore, it must either have a separate driving means or if dependent on the rotation of the grinding wheel, it must have some sort of a braking device.

It has been discovered that a diamond impregnated roller or a roller having diamonds or other hard-substances set therein or a carbide roller mounted at an angle greater than 30 and preferably about 45 to the grinding wheel, freely rotatable and slidably supported on a suitable carriagefor traversing across the face of a grinding wheel, is a decided improvement over the devices described above. It can dress a wheel with fewer passes than a single point diamond and with no measurable wear .per pass. Since each diamond is only in contact with the grinding wheel for a short period of time, there is practically no heat generated and the life of the individual diamond is correspondingly increased. Because of the angular setting of the roller, the roller is driven by the wheel at a speed in proportion to the angle and thus neither a braking device nor a separate driving device is necessary. The long wearing quality of this type of dressing device provides additional beneficial results, in that, wear of the dressing tool is not rapid enough to cause taper. Because of the angular relation between the roller and wheel, metal which has become embedded in the grinding wheel, is removed much more effectively than with a single or multiple traversing diamonds.

The roller type dressing tool described herein may also be used for profile dressing on the face and corners of a grinding wheel. This may be accomplished by using a profile bar with a follower having substantially the same diameter as the dressing roller.

It is an object of this invention to provide a dressing tool which will maintain a constant diameter across the peripheral face of the grinding wheel.

A further object is to provide a dressing tool in the form of a roller composedof solid materials or embedded particles of a hardness of 9 or more on the Mob scale.

A further object is to provide a dressing roller having embedded therein cutting particles of a size such that they number less than 50 particles per carat.

A further object is to provide a dressing roller rotatably mounted for rotation by engagement with a rotating grinding wheel, the rate of rotation being determined only by the angular relation between the dressing roller and the grinding wheel.

A further object is to provide a rotatable dressing device having -a plurality of diamonds, each of which engages the wheel only momentarily in a direction inclined to the direction of rotation of the grinding wheel.

A further object is to provide means for initiating the rotation of the dressing roller before it engages the :grinding wheel.

A further object is to provide means for guiding said dressing roller around the corners of a grinding wheel.

A further object is to provide an adjustable profile bar for guiding said dressing roller which may be adjusted to compensate for reduction in diameter of the roller due to wear.

A further object is to provide a dressing device which will effect an improved dressing operation with a reduced change in wheel diameter per dressing.

A further object is to provide means whereby each diamond on the roller effects a digging action on the wheel rather than a mere passageacross the face of the wheel. This action has the effect of removing metal cuttings from the wheel with less reduction in the diameter of the wheel than is caused by the use of conventional non-rotatable diamond dressers. Because of the minimum reduction in diameter of the wheel, the wheel dressed by this device lasts as much as 30% longer than wheels dressed by conventional dressing tools.

The preferred embodiment ofthe invention has been illustrated by way of example on the accompanying drawings in which- FIGURE '1 is 'a front elevation partly in section of a roller-type dresser showing the profile bar and follower, and the motor for traversing the dresser across a grinding wheel.

FIGURE 2 is an enlarged end elevation of the dressing tool showing its inclined relation to the grinding wheel.

FIGURE 3 is .a transverse vertical section on the 'line 33 of FIGURE 2.

FIGURE 4 is an enlarged front elevation of the .adjustable profile bar and follower.

FIGURE 5 is arr-enlarged end elevation of the adjustable pro-file bar and follower.

FIGURE 6 is a diagram showing the path of travel of individual diamondparticles across the face of the grinding wheel.

FIGURE 7 is a partial end elevation of a double disc grinder with one disc broken away to show a roller-type dresser adapted for dressing the opposing abrasive discs.

FIGURE 8 is a transverse section on the line S8 of FIGURE 7 and FIGURE 9 is a sectional end elevation of the dresser feed mechanism.

Numeral 10 indicates a support member on a grinding machine for supporting a dressing device. A cylinder 11 attached to support member 10 has a sleeve or liner 12 in which a piston 13 is slidably mounted. Dresser carriage 14 is slidably supported on member 10. Piston rod 15, extending from the left end of cylinder 11, is attached to dresser carriage 14 by means of lug 16 on said carriage.

A dressing tool mounted for vertical adjustment in dresser carriage 14 consists of a cylindrical guide member 20 in which is slidably mounted a tool holder 21, at the lower end of which is attached an angularly adjustable member 22'. A dressing roller 22 is rotatably mounted in member 22' for rotation in a plane or direction of rotation about 45 inclined to the plane or y direction of rotation of grinding wheel 23. The means for eifecting said vertical adjustment consists of a screw 24 inserted into a pair of axially spaced

nuts

25 and 26 in tool holder 21. A spring 27 between said nuts 25 and 26, serves as a means for taking up backlash. Knob 28 resting on the top of screw 24 provides means for effecting manual adjustment of roller 22 toward and from grinding wheel 23.

While the primary purpose of dresser roller 22 is the dressing of a straight grinding surface on a grinding wheel, formed surfaces may be dressed by using roller 22 in combination with a profile bar. A profile bar consisting of members and 36 substantially identical in shape, are mounted side by side for relative adjustment longitudinally of one another and are mounted in bracket 37 attached to a suitable stationary part of the dresser mounting 11. The relative adjustment of

members

35 and 36 is effected by means of adjusting screws 46 for member 35 and adjusting screws 41 for member 36.

Guide piston 42 in cylinder 43 is urged downwardly by means of spring 44. Piston 42 has a piston rod 45 which is connected in a suitable manner to the upper end of tool holder 21. Follower roller 46 is rotatably mounted in bracket 47. Bracket 47 is attached to piston rod 45 by means of screws 48 and 49. Spring 44 serves to maintain operative engagement between roller 46 and

profile members

35 and 36 so as to effect a precise movement of roller 22 relative to grinding wheel 23. If necessary, bracket 47 and roller 46 may be positioned angularly relative to the

profile members

35 and 36 to correspond to the position of roller 22 relative to grinding wheel 23. However, the advantage of such an arrangement is so slight as to be practically negligible except in cases requiring unusual precision.

The primary purpose of this adjustment is to compensate for change in the diameter of roller 22. As roller 22 wears,

members

35 and 36 are extended equally in opposite directions so as to increase the length of the profile bar by an amount corresponding to, but not necessarily equal to the wear of roller 22.

Roller 22 is in the form of a ring having a plurality of diamond Or other hard particles'mounted in the peripheral surface thereof and is attached to cylindrical member 60 having a large diameter end 61 and a small diameter end 62. When roller 22 is used for the purpose of dressing the corners as well as the face of the wheel 23, it may be desirable to extend the operative surface to include a radius on each corner of said roller 22 with cutting particles distributed over the radius the same as on the face of roller 22.

The size of the diamond particles is such that they number about particles or less per carat. Roller 22 is mounted on the small diameter end 62 and held against the shoulder at the junction of said small diameter end 21. and said large diameter end by means of collar 63 and nut 64.

Cylindrical member 60 is rotatably mounted on a stationary shaft 70 held against rotation at the left end of bracket 71 by means of screw 72 and cap 72, and at the right end of said bracket 71 by cap 73 and screws 74. Member 60 is rotatably supported on anti-friction bearings '75 and 76. The outer rings of said bearings are held in spaced relation by sleeve 80. The inner rings of said bearings are held in spaced relation under load by a member consisting of a spool 81 mounted on shaft 70 and having flanged portions 82. Between spool 81 and each of said inner bearing rings is a resilient member 83 also mounted on shaft 70 and having a hub portion extending axially outwardly to engage the inner rings and a rim portion extending inwardly to engage the flanged portions 82 of spool 81.

An axial bore in shaft 71 is connected through a radial bore 91 through groove 92 with the outer surface of shaft 70 in alignment with a plurality of radial openings 93 and spool 81. Bore 9G is also connected through radial passages 1th? in the left end of shaft 70 which are connected through radial bores 101 in ring 102 through a plurality of non-radial outlets 103 in member 60. Ring 102 is pressed into member 60 and is preferably of softer material than shaft 70 or member 60.

Air and oil mist is introduced under pressure in bore 90 and is distributed through bores 101 and openings 93 in spool 81 to provide lubricant for bearings 75 and 76. This air and oil mist produces an outward pressure on said bearings to prevent the entry of water or dirt into said bearings. The air under pressure is also directed from bore 90 through passages and outlets 103 to provide a preliminary rotation of member 60 and roller 22.

Roller 22 may be attached to tool holder 21 in a fixed position for rotation in a direction at an inclination to the direction of rotation of the wheel. It may also be mounted for angular adjustment if such adjustment is required or if it appears to be desirable. The preferred angle of roller 22 relative to wheel 23 is approximately 45. As indicated above, preliminary rotation of roller 22 is effected before roller 22 engages wheel 23.

Thereafter, the action of wheel 23 on roller 22 will continue the rotation of roller 22 at a surface speed approximately half of that of wheel 23 for a 45 setting. It must be remembered that roller 22 is mounted for free rotation on shaft 70, and its rate of rotation is dependent entirely upon the surface speed of wheel 23 modified by the angular relation between roller 22 and wheel 23.

FIGURE 6 shows the direction of cut of one of the diamonds in roller 22 on wheel 23. The speed of wheel 23 is indicated by line A. The speed of roller 22 is indicated by line B. Assuming that the diamond X has just engaged the peripheral surface of wheel 23, the point of contact of the diamond with the wheel moves in the direction of line A while the diamond moves in the direction of line B. During this time, roller 22 itself has moved in a horizontal direction to the end of line B. While the point on the wheel travels the distance indicated by line A, the diamond is travelling the distance indicated by line B. The resultant path or cut of the diamond on wheel 23 is in the direction of line C. The resultant path on wheel 23 of a particular point on roller 22 is line C joining lines A and B. This lines is substantially parallel to the axis of roller 22. The path of each of the other diamonds of roller 22 on wheel 23 is in the same direction and of the same length as that of diamond X. Each diamond is thus in contact with wheel 23 for a very short period at a time, so that very little heat is generated in any individual diamond.

Because the dressing operation is distributed over a plurality of diamonds, the diamond wear is correspondingly distributed with the result that roller 22 crosses the face of wheel 23 and there is no wear which would result in a variation in diameter of wheel 23 from one 'end to the other. This represents a decided improvement over non-rotating dressers, one of the greatest faults of which is the dressing of a taper on Wheel 23 due to the wear of the diamond as it passes across the operative face of said wheel. An example of an application of this type of dresser would include a grinding whe'el having a peripheral surface speed of 8000 feet per minute. A dressing roller set to rotate at an angle of 45 to the direction of rotation of the wheel will be driven by the wheel at a surface speed of approximately 4000 feet per minute.

The resulting effect produced by all the diamonds in roller 22 on wheel 23, is a plurality of lines such as line C. Thus, the peripheral lines which are the usual effect of single or multiple diamond fixed tools and which often produce a corresponding pattern on the surface of a workpiece, are completely eliminated by providing a dressing tool which makes a pltu'ality of short cuts inclined to the direction of rotation of the wheel rather than continuous cuts parallel with the direction of the wheel.

The principal effect of this type of dresser on a grinding wheel is that dressing is performed by a plurality of diamonds, each taking a relatively small cut so that the wear on each diamond is so slight as to be negligible. The result of this arrangement is that as the dressing roller passes across a grinding wheel, wear on the diamonds is so distributed that at the end of a pass of the dressing roller across the wheel, the wheel is the same diameter at both ends and, therefore, will grind a work surface of constant diameter rather than a taper.

Another effect of this type of dresser on a grinding wheel is that each diamond, as it rotates on the roller, enters the surface of the grinding wheel, penetrating to a depth depending upon the radius of the roller and then rotates out of contact with the wheel. This action of the diamond is more effective in removing metal particles from the abrasive surface than the conventional dressing tool, and thus requires fewer passes of the dressing roller and less reduction in wheel diameter for each dressing operation.

In FIGURES 7 and 8, the spaced grinding

discs

120 and 121 are dressed by movement of a dressing arm 125 between said discs. Arm 125 may be pivotally mounted as shown in the drawings in which a pneumatic-hydraulic device 126 is anchored in frame 127 and attached to arm 125 through link 128. It may be mounted for sliding movement as shown, for example, in US. Patent application Serial No. 742,595, filed June 17, 1958 issued as Patent No. 3,018,589, dated January 30, 1962.

Regardless of whether arm 125 is pivotally or slida'bly mounted, it carries at one end a pair of oppositely positioned rollers 130 substantially identical with roller 22 of FIGURES 2 and 3. Rollers 130 are angularly positioned in arm 125 so as to rotate in a direction at an angle of approximately 45 to their path of travel across

discs

120 and 121. Here again, the effect of negligible wear of the diamonds plus the absence of peripheral or annular diamond lines on the discs, make for a sub stantial improvement in the quality of work produced on a machine equipped with this type of dresser.

The invention as described and illustrated above by way of example is capable of minor change in arrangement and material without departing from the scope as defined in the following claims.

I claim:

1. In a grinding machine, a rotatably mounted grinding wheel, a dressing tool, means for effecting a relative transverse and axial movement between said dressng tool and said grinding wheel, said dressing tool comprising a diamond dressing roller mounted for free rotation in an oblique direction inclined more than 45 degrees to the direction of rotation of said grinding wheel whereby said roller is driven by said grinding wheel at a surface speed substantially different than that of the grinding wheel and means for dressing a predetermined form on said grinding wheel comprising a fixed forming bar, a follower connected to said roller and mounted for operative engagement with said forming bar, the portion of said follower engaging the forming bar being substantially the same shape and diameter as the dressing roller.

2. In a grinding machine, a rotatably mounted grinding wheel, a dressing tool, means for effecting a relative transverse and axial movement between said dressing tool and said grinding wheel, said dressing tool comprising a roller mounted for free rotation in an oblique direction inclined more than 45 degrees to the direction of rotation of said grinding wheel whereby said roller is driven by said grinding wheel at a surface speed substantially different than that of the grinding wheel and means for dressing a predetermined form on said grinding wheel comprising a fixed forming bar, a follower connected to said roller and mounted for operative engagement with said forming bar, the portion of said follower engaging the forming bar being substantially the same shape and diameter as the dressing roller, said forming bar consisting of a pair of profile members longitudinally adjustable relative to one another to compensate for Wear on said dressing roller.

-3. In a dressing devicefor a rotatable grinding wheel, a dressing tool, supporting means for said dressing tool, means for effecting a relative transverse movement between said supporting means and the operative surface of said grinding wheel, said dressing tool comprising a holder mounted in said supporting means, a diamond dressing roller rotatably mounted for free rotation in said holder, power means for effecting a preliminary rotation of said roller before it engages the grinding wheel, said roller being driven by said grinding wheel after said engagement, the relation between said roller and said grinding wheel being such that the surface speed of said roller is approximately half the surface speed of said grinding wheel.

4. In a dressing device for a rotatable grinding wheel, a dressing tool, supporting means for said dressing tool, means for effecting a relative transverse movement between said supporting means and the operative surface of said grinding wheel, said dressing tool comprising a holder mounted in said supporting means, a diamond dressing roller rotatably mounted for free rotation in said holder, said roller being positioned so as to rotate at an angle to the direction of rotation of said grinding wheel, and power means for effecting a preliminary rotation of said roller before it engages said grinding wheel.

5. In a dressing device for a rotatable grinding Wheel, a diamond dressing tool, supporting means for said dressing tool, means for effecting a relative transverse movement between said supporting means and the operative surface of said grinding wheel, said dressing tool comprsing a holder mounted in said supporting means, a dressing roller rotatably mounted for free rotation in said holder, a supply of fluid under pressure, and means on said roller co-acting with said fluid under pressure to cause a preliminary rotation of said roller prior to engagement of the roller and the grinding wheel.

6 In a dressing device for a rotatable grinding wheel, a dressing tool, supporting means for said dressing tool, means for effecting a relative transverse movement between said supporting means and the operative surface of said grinding wheel, said dressing tool comprising a holder mounted in said supporting means, a dressing roller rotatably mounted for free rotation in said holder, means for effecting a preliminary rotation of said roller before it engages the grinding wheel, a supply of fluid under pressure, passages for said fluid through said roller and discharge openings connected to said passages and peripherally spaced in said roller for effecting rotation of said roller in response to passage of said fluid through said discharge openings.

7. In a dressing device for a rotatable grinding wheel, a dressing tool, supporting means for said dressing tool, means for effecting 'a relative transverse movement between said supporting means and the operative surface of said grinding wheel, said dressing tool comprising a holder mounted in said supporting means, a shaft in said holder, anti-friction bearings axially spaced on said shaft, a dressing roller rotatably mounted for free rotation on said bearings, means for effecting a preliminary rotation of said roller before it engages the grinding Wheel, comprising a supply of air under pressure mixed with a lubricant, passages through said roller for directing a portion of said air to provide a pressure within said roller greater than the pressure outside said roller and passages for directing another portion of said air to peripherally spaced points of discharge on said roller.

8. In a dressing device for a rotatable grinding wheel, a dressing tool, supporting means for said dressing tool, means for effecting a relative transverse movement between said supporting means and the operative surface of said grinding wheel, said dressing tool comprising a holder mounted in said supporting means, a diamond dressing roller rotatably mounted for free rotation in said holder, said roller comprising a supporting shaft, anti-friction bearings axially spaced on said shaft, a sleeve rotatably supported on said bearings, a turbine drive means co-acting with said sleeve, a collar on said sleeve, abrasive particles distributed about the peripheral surface of said collar, a supply of fluid under pressure consisting of air and a lubricant in the form of a mist,

8 and means for directing said fluid under pressure to a (point in said sleeve whereby to lubricate said bearings to drive said turbine means and to prevent undesirable elements from entering said bearings.

9. In a dressing device for a rotatable grinding wheel, a dressing tool, supporting means for said dressing tool, said dressing tool comprising a holder mounted in said supporting means, a dressing roller rotatably mounted for free rotation in said holder, means for effecting a preliminary rotation of said roller before it engages the grinding wheel, a supply of fluid under pressure, passages for said' fluid through said roller and discharge openings connected to said passages and peripherally spaced in said roller for effecting rotation of said roller in response to passage of said fluid through said discharge openings.

References Cited in the file of this patent UNITED STATES PATENTS 1,687,252 Laessker Oct. 9, 1928 1,860,614 Hohnhorst May 31, 1932 2,135,202 Scrivener Nov. 1, 1938 2,380,451 Koebel July 31, 1945 2,528,621 Sweetser Nov. 7, 1950 2,809,474 Newman Oct. 15, 1957 2,861,561 Olson Nov. 25, 1958 FOREIGN PATENTS 896,678 France Feb. 28, 1945