GB1587208A

GB1587208A - Method and apparatus for trueing or profiling grinding wheels

Info

Publication number: GB1587208A
Application number: GB5057377A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1976-12-08
Filing date: 1977-12-05
Publication date: 1981-04-01
Also published as: DE2655533A1; FR2373363A1

Description

(54) METHOD AND APPARATUS FOR TRUEING OR PROFILING GRINDING WHEELS (71) I, ERNST SALJE, of Schulheide 4, D-2106 Bendestorf, Germany, a German Citizen, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described, in and by the following statement: The inventidn relates to a method and apparatus for trueing or profiling of grinding wheels, particularly grinding wheels with diamond or cubic crystalline boron nitride (CBN) as cutting material, in which the grinding wheel and a trueing or profiling tool are brought into engagement with each other.

The use of a rolling tool is known for trueing or profiling of conventional form grinding wheels. The rolling tool and the grinding wheel are thrust radially against each other and are made to roll upon each other. A procedure of this kind is also known as crushing. Grinding wheel bonds have since been developed which will allow profiles to be crushed into diamond or CBN grinding wheels.

The invention is concerned with means whereby trueing or profiling of grinding wheels, particularly of diamond and CBN grinding wheels, can be performed by means of a tool in a particularly advantageous and effective manner and the desired state of the grinding wheel suitable for the particular application can be achieved in a relatively short time.

The invention provides a method of trueing or profiling a grinding wheel, comprising engaging the rotating grinding wheel and a trueing or profiling tool with each other, the tool having a crushing roll which rotates with the grinding wheel, and subjecting the tool to continuous oscillating motion in a direction which is perpendicular to a plane containing the grinding wheel axis and passing through the point of contact between the tool and the grinding wheel, so that forces of alternating direction are applied to the grinding wheel by the crushing roll.

In the method according to the invention the additional movement of the tool, superimposed on the rotation of the grinding wheel during the trueing operation, causes forces of alternating direction to be applied to the grinding grains or grinding particles of the grinding wheel.

The application of force of this kind with an alternating direction leads to effective loosening of the grinding grains or particles in their bond so that they are detached from their bond in the manner which is desirable for trueing or profiling.

Relatively large stock removal rates can be achieved by the method according to the invention not only with conventional grinding wheels but also with grinding wheels of diamond or boron nitride cutting materials, so that the trueing or profiling operation can be performed in shorter times and more efficiently than hitherto.

The invention also provides apparatus for trueing or profiling a grinding wheel, comprising holding means rotatably holding a crushing roll which is to be brought into engagement with a rotating grinding wheel, and drive means for subjecting the holding means to continuous oscillating motion in a direction perpendicular to a plane containing the grinding wheel axis and passing through the point of contact between the crushing roll and the grinding wheel, so that forces of alternating direction are applied to the grinding wheel by the crushing roll.

The contact force, i.e. the force which thrusts the grinding wheel and the crushing roll against each other during the operation can be applied, for example manually, by the feed device of the relevant grinding machine on the spindle of which is clamped the grinding wheel that is to be trued or profiled. The device can be accommodated on the platen of the grinding machine, or, depending on the construction of the grinding machine, on some other element thereof.

The device itself can also be provided with means for applying the necessary contact force for the operation. This can be advantageous, for example if the feed direction of the grinding machine to be used does not coincide with the feed direction required for trueing or profiling or if the profiling operation is to be performed independently of a grinding machine.

A feed device can be provided, more particularly on the side of the crushing roll. It is, however, possible to provide the device with its own spindle, which can be drivable, for the grinding wheel which is to be trued or profiled. A feed device for applying the contact pressure can then also be provided on the grinding wheel holder.

Irrespective of whether the grinding wheel which is to"be trued or profiled is situated on the spindle of a grinding machine or on a spindle which is provided in the apparatus itself, the system can be arranged so that the grinding wheel is rotatingly driven while the said crushing roll is entrained by the grinding wheel during operation. The apparatus may be provided with a drive for the crushing roll, thus dispensing with the need for a rotational drive for the grinding wheel.

The part which accommodates the roll or a table supporting such a part is conveniently guided on a base in the direction of the alternating motion. To this end it is possible to provide guides, for example fixed guides which can extend rectilinearly or curvilinearly. In a particularly advantageous embodiment of the device the roll bearing part or a table supporting the same is suspended by leaf springs. This enables a stable means of support to be obtained combined with a reliably guided motion.

There are different means for generating the continuous oscillating motion of the crushing roll holding means. An alternating force generator is advantageously provided for generating such motion. The oscillating drive can operate mechanically, electrically, or with pressure media. Inter alia it is possible to provide an electrohydraulic generator of alternating force which can be controlled, for example by means of a servo valve.

Conveniently the oscillating drive is embodied so that the frequency and amplitude of the oscileating motion can be varied and can thus be selected in accordance with the prevailing conditions.

In addition to the trueing or profiling tool the apparatus can also have a rotatingly drivable supplementary tool, such as a ripper wheel, which can be engaged with or disengaged from the grinding wheel which is to be trued or profiled.

More particularly the action of a ripper wheel is to cut back the bond of the grinding wheel so that the grains of grinding grit project from the bond. This also applies inter alia to grinding wheels with resin bonds. The ripper wheel can be a conventional corundum or silicon carbide wheel. It is convenient for the ripper wheel to be set into rotation while it is in operation so that it is uniformly worn. Conventional means can be provided for the rotational drive of the supplementary tool. The rotation can also be derived from the grinding wheel drive by means of a centrifugal brake. The supplementary tool can be thrust by means of weight loading against the grinding wheel which is to be trued or profiled.

Further details, features and advantages of the invention are disclosed in the description hereinbelow in conjunction with the accompanying drawing. This shows in substantially diagrammatic form one embodiment of apparatus constructed in accordance with the invention.

A grinding wheel 1 which is to be trued or profiled is mounted by means of a flange 2 on a rotatingly drivable spindle 3. The spindle 3 can be the spindle of a grinding machine or a spindle associated with the apparatus and can be a spindle which is supported in a slide 4 indicated by dash-dot lines 4. A slide 4 of this kind can traverse in the sense of a feed motion in guideways 5 on the frame 6 of the apparatus by means of a drive (not shown).

A crushing roll 7, consisting of steel or hard metal and having a profile which corresponds to the profile to be produced in the grinding wheel 1, is rotatably supported in a bearing pedestal 8 which in turn is mounted by means of screw fasteners on an oscillating table 9. The table 9 is suspended by means of two broad leaf springs 10, the bottom ends of each of which are clamped in bottom strip extensions 11 of the table 9, while the top ends are mounted in pedestal holders 12 which are supported by a base 27. The table 9 is retained by this suspension system in a friction-free and movable manner in such a way that it is able to perform a reciprocating motion on a slightly curved path in a direction transverse to the normal N which extends through the point of contact B between the crusher roll 7 and the grinding wheel 1.

An electrohydraulic alternating force generator 13, which can be controlled by a servo valve 14 and is capable of delivering oscillations of preselectable frequency and amplitude to the output formed by a tappet 15 is provided to generate an alternating motion of the table 9 with the crusher roll 7. The energy supply lines and the means for adjusting frequency and amply tude are not separately shown. They can be conveniently embodied, with means available to the expert.

The tapper 15 of the alternating force generator 13 is connected to an extension 16 of the table 9 by means of a coupling 17 which comprises a slack-free link so that the tappet 15, which operates only rectilinearly, cannot be influenced by the slightly arcuate motion of the table 9.

On the opposite side the table 9 can bear by means of a compression spring 18 against a stationary abutment 19 which is connected to the frame 6 of the device. To this end an extension 9a of the table can engage in a bore 1 9a of the abutment 19 with a radial clearance which will not obstruct the motion of the table.

The frame 6 or a part of the device connected thereto supports a geared motor 20 by means of which a ripper wheel 21, consisting of corundum, can be rotatingly driven via a belt drive 22. The ripper wheel 21 is supported at the end of a cutting arm 23 whose top end is retained by part of the geared motor 20 or by a separate bearing system. In the sense of thrusting the ripper wheel 21 against the grinding wheel 1 the pivoting arm 23 is biased by a force applied by a weight 24 which is suspended from a rope 26 or other pull element, which is guided over the roller 25 and whose other end is mounted on the pivoting arm 23.

When the apparatus is in operation the rotatingly driven grinding wheel 1 entrains the crusher roll 7, against which it is thrust, by appropriate adjustment of the feed device of a grinding machine or the slide 4 of the apparatus itself. The grinding wheel 1 is turned or profiled by this rolling operation with a profile defined by the shape of the crusher roll 7. In this operation the bond of the grinding wheel 1 is cut back by the rotating ripper wheel 21 to enable the grains of grinding grit to extend from the bond and thus to assist the trueing or profiling operation.

The alternating force generator 13 imparts to the table 9 and therefore to the crusher roll 7 an alternating oscillating motion which is superimposed on the rolling motion and takes place perpendicularly to the plane which contains the normal N and the grinding wheel axis.

Accordingly, the grains of grinding grit of the grinding wheel 1 are constantly stressed with alternating and approximately tangential forces so that they are loosened in a particularly effective manner and are detached from the bond.

This results in relatively large stock removal rates not only in grinding wheels of the conventional kind but more particularly in grinding wheels with diamond or CBN cutting materials so that even grinding wheels of this kind can be efficiently trued and profiled by means of a crusher roll.

To produce a contact force between the crusher roll 7 and the grinding wheel 1 the device can also be provided with feed means on the side of the crusher roll. There are various possibilities. In one embodiment the bearing pedestal for the crusher roll 7 can be adjustable relative to the table 9 in the direction of the normal N, for example by means of a pin clutch.

However, the entire unit comprising the table 9 with its holding means 12 as well as the drive 13 and including the base or baseplate 27 can be constructed as a slide which is adjustable relative to the frame 6 in the direction of the normal N.

WHAT I CLAIM IS: 1. A method of trueing or profiling a grinding wheel, comprising engaging the rotating grinding wheel and a trueing or profiling tool with each other, the tool having a crushing roll which rotates with the grinding wheel, and subjecting the tool to continuous oscillating motion in a direction which is perpendicular to a plane containing the grinding wheel axis and passing through the point of contact between the tool and the grinding wheel, so that forces of alternating direction are applied to the grinding wheel by the crushing roll.

2. Apparatus for trueing or profiling a grinding wheel, comprising holding means rotatably holding a crushing roll which is to be brought into engagement with a rotating grinding wheel; and drive means for subjecting the holding means to continuous oscillating motion in a direction perpendicular to a plane containing the grinding wheel axis and passing through the point of contact between the crushing roll and the grinding wheel, so that forces of alternating direction are applied to the grinding wheel by the crushing roll.

3. Apparatus as claimed in Claim 3, including means for applying a thrust between the crushing roll and the grinding wheel, having a part which is adjustable in the direction of the nor may which extends through the point of contact between the crushing roll and the grinding wheel 4. Apparatus as claimed in Claim 3, in which the holding means is mounted on the adjustable part.

5. Apparatus as claimed in Claim 3, including a rotatable holder for the grinding wheel, mounted on the adjustable part.

6. Apparatus as claimed in any of Claims 2 to 5, including guide means for guiding the holding means in the direction of oscillating motion.

7. Apparatus as claimed in any of Claims 2 to 6, in which the holding means is suspended by leaf springs.

8. Apparatus as claimed in any of Claims 2 to 7, including means for driving the crushing roll in rotation.

9. Apparatus as claimed in any of Claims 2 to 8, in which the oscillating drive means comprises an alternating force generator.

10. Apparatus as claimed in any of Claims 2 to 9, in which the holding means bears by means of spring means against a stationary abutment on a side opposite to the drive means.

11. Apparatus as claimed in any of Claims 2 to 10, further comprising a rotatingly drivable supplementary tool selectively engageable with and disengageable from the grinding wheel.

12. A method of trueing or profiling a grinding wheel, substantially as described herein with reference to the accompanying drawing.

13. Apparatus for trueing or profiling a grinding wheel, substantially as described herein with reference to, and as shown in, the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

23 is biased by a force applied by a weight 24 which is suspended from a rope 26 or other pull element, which is guided over the roller 25 and whose other end is mounted on the pivoting arm 23.

When the apparatus is in operation the rotatingly driven grinding wheel 1 entrains the crusher roll 7, against which it is thrust, by appropriate adjustment of the feed device of a grinding machine or the slide 4 of the apparatus itself. The grinding wheel 1 is turned or profiled by this rolling operation with a profile defined by the shape of the crusher roll 7. In this operation the bond of the grinding wheel 1 is cut back by the rotating ripper wheel 21 to enable the grains of grinding grit to extend from the bond and thus to assist the trueing or profiling operation.

The alternating force generator 13 imparts to the table 9 and therefore to the crusher roll 7 an alternating oscillating motion which is superimposed on the rolling motion and takes place perpendicularly to the plane which contains the normal N and the grinding wheel axis.

Accordingly, the grains of grinding grit of the grinding wheel 1 are constantly stressed with alternating and approximately tangential forces so that they are loosened in a particularly effective manner and are detached from the bond.

This results in relatively large stock removal rates not only in grinding wheels of the conventional kind but more particularly in grinding wheels with diamond or CBN cutting materials so that even grinding wheels of this kind can be efficiently trued and profiled by means of a crusher roll.

To produce a contact force between the crusher roll 7 and the grinding wheel 1 the device can also be provided with feed means on the side of the crusher roll. There are various possibilities. In one embodiment the bearing pedestal for the crusher roll 7 can be adjustable relative to the table 9 in the direction of the normal N, for example by means of a pin clutch.

However, the entire unit comprising the table 9 with its holding means 12 as well as the drive 13 and including the base or baseplate 27 can be constructed as a slide which is adjustable relative to the frame 6 in the direction of the normal N.

WHAT I CLAIM IS: 1. A method of trueing or profiling a grinding wheel, comprising engaging the rotating grinding wheel and a trueing or profiling tool with each other, the tool having a crushing roll which rotates with the grinding wheel, and subjecting the tool to continuous oscillating motion in a direction which is perpendicular to a plane containing the grinding wheel axis and passing through the point of contact between the tool and the grinding wheel, so that forces of alternating direction are applied to the grinding wheel by the crushing roll.
2. Apparatus for trueing or profiling a grinding wheel, comprising holding means rotatably holding a crushing roll which is to be brought into engagement with a rotating grinding wheel; and drive means for subjecting the holding means to continuous oscillating motion in a direction perpendicular to a plane containing the grinding wheel axis and passing through the point of contact between the crushing roll and the grinding wheel, so that forces of alternating direction are applied to the grinding wheel by the crushing roll.
3. Apparatus as claimed in Claim 3, including means for applying a thrust between the crushing roll and the grinding wheel, having a part which is adjustable in the direction of the nor may which extends through the point of contact between the crushing roll and the grinding wheel
4. Apparatus as claimed in Claim 3, in which the holding means is mounted on the adjustable part.
5. Apparatus as claimed in Claim 3, including a rotatable holder for the grinding wheel, mounted on the adjustable part.
6. Apparatus as claimed in any of Claims 2 to 5, including guide means for guiding the holding means in the direction of oscillating motion.
7. Apparatus as claimed in any of Claims 2 to 6, in which the holding means is suspended by leaf springs.
8. Apparatus as claimed in any of Claims 2 to 7, including means for driving the crushing roll in rotation.
9. Apparatus as claimed in any of Claims 2 to 8, in which the oscillating drive means comprises an alternating force generator.
10. Apparatus as claimed in any of Claims 2 to 9, in which the holding means bears by means of spring means against a stationary abutment on a side opposite to the drive means.
11. Apparatus as claimed in any of Claims 2 to 10, further comprising a rotatingly drivable supplementary tool selectively engageable with and disengageable from the grinding wheel.
12. A method of trueing or profiling a grinding wheel, substantially as described herein with reference to the accompanying drawing.
13. Apparatus for trueing or profiling a grinding wheel, substantially as described herein with reference to, and as shown in, the accompanying drawing.