GB1585152A

GB1585152A - Method and apparatus for profiling a grinding wheel

Info

Publication number: GB1585152A
Application number: GB25998/78A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1977-07-11
Filing date: 1978-05-31
Publication date: 1981-02-25
Also published as: FR2397269A1; DE2731223A1; IT1095163B; IT7824460A0; JPS5419293A; CH631375A5

Abstract

The grinding wheel (1) to be profiled is arranged on a carrier (13) and driven by a motor (2). The carrier (13) is fastened on an optical projection-form grinding machine such that the point of engagement of the grinding wheel (1), to be profiled, and the profiling grinding wheel (14) of the projection-form grinding machine is located in the region of the axis (7) of the optical imaging system (16, 17, 18). The mutual position of the two grinding wheels (1, 14) is changed, using the imaging of the point of engagement, corresponding to the desired profiling by means of the pivot lever (20). This makes possible the high-precision profiling of a grinding wheel (1) with any profile using a single profiling grinding wheel (14). <IMAGE>

Description

(54) METHOD AND APPARATUS FOR PROFILING A GRINDING WHEEL (71) I, ALFRED KOLB, a German Citizen of Haus am Tannenberg, 6980 Wertheim, Germany, 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 invention relates to a method of profiling a grinding wheel which is mounted on a carrier and is rotated by a drive, and also to an apparatus for carrying out that method.

It is known to profile a grinding wheel by rotating the wheel and profiling the wheel by hand using a dressing diamond or a diamond file. Devices are also known for profiling grinding wheels by guiding the wheels against dressing rollers which are accurately shaped in accordance with the desired profile. Devices of this kind have the disadvantage that for every desired profile a separate dressing roller must be provided, and that if the shape of the dressing roller changes there will be defects in the profile of the grinding wheel.

An apparatus of this kind in which the point of engagement between the grinding wheel which is to be profiled and the dressing roller can be observed by means of an adjusting optical system is described in DT GBM No. 7,436,857. In this apparatus the driven grinding wheel is fastened to a carrier and is brought into engagement alternately with the workpiece which is to be machined and a dressing roller having the required shape appropriate to the particular workpiece. Correct adjustment of the grinding wheel which is to be profiled relative to the dressing roller is achieved and checked with the aid of the adjusting optical system described in the Gebrauchsmuster. This apparatus also has the disadvantage that a separate dressing roller is required for every desired profile, so that the adjustment of the grinding wheel which is to be profiled to its profiling position is relatively complicated.

It is a main object of the invention to provide a method and an apparatus for profiling a grinding wheel to any profile, particularly to a profile having the shape of an arc of a circle, with the greatest precision using a single profiling grinding wheel.

According to the invention there is provided a method of profiling a grinding wheel which is mounted on a carrier and is rotated by a drive, wherein the carrier is mounted on an optical projection form grinding machine in such a manner that the point of engagement of the grinding wheel which is to be profiled and of a profile grinding wheel of the machine lies in the region of the optical axis of an imaging system, and the mutual positions of the two grinding wheels are varied, by using the image of the point of engagement, in accordance with a desired profile to be ground on the grinding wheel.

The invention therefore proposes the use of an optical projection form grinding machine, which is known per se, for producing the desired profile of a grinding wheel. The driven grinding wheel which is to be profiled is held on a carrier in such a manner that the region in engagement with the profiling grinding wheel of the projection form grinding machine is imaged on a ground glass screen. The desired profile, which can be depicted on an enlarged scale on the ground glass screen, is now ground into the grinding wheel by guiding the profiling grinding wheel of the projection form grinding machine along this profile curve with the aid of the image on the ground glass screen.

It is also possible for the grinding wheel which is to be profiled to be moved relative to the profiling grinding wheel whose axis is then fixed. This procedure is particularly advantageous when producing profiles having the shape of an arc of a circle. Preferably the grinding wheel which is to be profiled is positioned relative to the optical axis of the imaging system in such a way that the optical axis extends through the centre of the circular arc profile which is to be produced, the profile grinding wheel is rotatably mounted on a fixed axis in such a way that its active periphery is at a distance corres ponding to the desired profile radius from the optical axis of the imaging system, and the carrier is swivelled about the optical axis of the imaging system relative to the pro jection form grinding machine.

In this process circular arc profiles of different radii can be produced with a single profile grinding wheel by varying the distance between the profile grinding wheel and the optical axis. When the carrier hold ing the grinding wheel which is to be pro filed is swivelled about the optical axis a circular arc profile is necessarily formed on the periphery of the grinding wheel.

The invention also comprehends appara tus for carrying out the method of the invention, comprising a carrier holding a driven grinding wheel which is to be pro filed, which carrier is mounted on an optical projection form grinding machine in such a manner that the point of engagement of the grinding wheel which is to be profiled and of a profile grinding wheel lies in the region of the optical axis of an imaging system of the machine and an image of the point of engagement is formed on the ground glass screen of the projection form grinding machine.

More particularly, for the production of a profile having the shape of an arc of a circle, the carrier is swivellable about the optical axis of the imaging system, the grind ing wheel which is to be profiled is held on the carrier for displacement relative to the optical axis and is so adjusted that the optical axis extends through the centre point of the circular arc profile which is to be produced, and the profile grinding wheel is so positioned that its active peripheral sur face is at a distance from the optical axis corresponding to the desired radius of the circular arc profile.

The profile- grinding wheel may have the same radius over its whole periphery.

In order that the invention may be more clearly understood some embodiments thereof will now be described, by way of example, with reference to the accompany ing drawings, in which: Figure 1 is a front view in perspective of a grinding wheel profiling device according to the invention, Figure 2 is a rear view in perspective of the device shown in Figure 1, and Figure 3 shows diagrammatically the images on a ground glass screen of an optical projection form grinding machine when forming a circular arc profile on a grinding wheel.

A grinding wheel 1 which is to be profiled, for example a grinding wheel of cubic boron nitride (CBN) is fastened on a shaft -4 which is driven through a gear unit 3 by an electric motor 2. The gear unit 3 carries the electric motor 2 together with the shaft 4 and the grinding wheel 1, and is mounted by means of a dovetail slide on a holder 5 for movement at right angles to the direction of the shaft 4. The holder 5, is articulated on a bearing plate 8 by means of an arm 6 for rotation about a vertical axis 7.

The bearing plate 8 is fastened on an upper table 9 of a compound support 12, which can be moved by two spindle drives in a manner known per se in two directions at right angles to one another, by manual operation of cranks 10, 11.

The compound support 12 is fastened in the usual way on the frame of an optical projection form grinding machine of known kind which is preferably provided with an index holder which is of the same construction as index holders of other devices which are usually fastened on an optical projection form grinding machine, such as for example the workpiece rest. In this way the above described unit including the gear unit 3, and the motor 2 which will be referred to as carrier 13, can be replaced immediately, for example by the workpiece rest of an optical projection form grinding machine.

A profile grinding wheel 14, preferably a grinding wheel of silicon carbide or diamond, is driven by a belt drive 15 and is mounted, in a manner not shown in the drawing, on the optical projection form grinding machine in such a way that it engages with the grinding wheel 1 which is to be profiled, for machining the wheel 1.

The region of engagement of the two grinding wheels 1 and 14 is projected by an optical imaging system on to a ground glass screen 21, Figure 3, as is customary in optical projection form grinding machines.

The optical imaging system comprises a light source 16 provided with a deflecting mirror 17 and an imaging optical system 18, together with other optical components of known type which are not shown in the drawing. In the arrangement shown in Figure 1 the optical axis of the imaging system coincides with the axis 7 about which the arm 6 rotates. To allow light to pass the swivel mounting of the arm 6 on the bearing plate 8 has a central bore 25.

In a first method for profiling the grinding wheel 1, the wheel 1 is moved by means of the hand cranks 10 and 11, and also optionally by means of a spindle drive 19 which slides the gear unit 3 relative to the holder 5, into a position in which the image of the periphery of the profile grinding wheel 14 is projected on the ground glass screen 21 over an image of the entire width of the perinhery of the wheel 1 which is to be profiled, there being an image on the ground glass screen of a desired curve. The profile grinding wheel 14 is then controlled as is usual for optical projection form grinding machines, so that the image of the periphery of the wheel 14 runs along the desired curve on the ground glass screen. The profile grinding wheel 14 thus grinds the desired profile in the grinding wheel 1. In this way even complicated profiles can be ground with the greatest precision.

In the method described the grinding wheel 1 which is to be profiled, is held in position during the grinding operation, while the profile grinding wheel 14 is moved in accordance with the profile which is to be ground.

For the production of a profile having the shape of an arc of a circle the method described below is suitable. By adjusting the compound rest 12 the carrier 13 is adjusted to bring the axis of the swivel mounting of the arm 6 relative to the bearing plate 8, into coincidence with the optical axis 7.

The gear unit 3 is moved relative to the holder 5 in such a way that the optical axis 7 passes through the grinding wheel 1 which is being profiled, at the centre point of the circular arc profile which is to be produced.

The profile grinding wheel 14 is so adjusted that its peripheral surface at the height of the shaft 4 of the grinding wheel 1 is situated at a distance from the optical axis 7 corresponding to the radius of the circular arc profile which is to be ground. When the arm 6 and the grinding wheel 1 mounted thereon are now swivelled by way of a swivelling lever 20 about the axis of rotation coinciding with the optical axis 7, a circular arc profile is ground on the grinding wheel 1.

The image formed on the ground glass screen 21 is shown in Figure 3. The optical axis is indicated on the screen for example, by the point of intersection A of two marking lines 2 and 23. The peripheral surface 24 of the profile grinding wheel 14 at a distance R, corresponding to the radius of the circular arc profile which is to be cut from the intersecting point A of the optical axis. The grinding wheel 1 which is to be profiled is so arranged that, with the aid of its carrier, it can be turned about the centre point of the circular arc profile which is to be ground. In Figure 3 the grinding wheel 1 is shown on the left-hand side in solid lines in a first swivelled position and on the right-hand side in broken lines in a second swivelled position. It can thus be seen that when the grinding wheel 1 is swivelled about the axis of rotation of the carrier, which coincides with the optical axis 7, there will be ground on the grinding wheel 1 a circular arc profile whose radius depends solely on the distance R between the profile grinding wheel 14 and the optical axis 7.

By this method it is thus possible, using a single profile grinding wheel 14, to grind circular arc profiles of different radii in a simple manner by adjusting the profile grinding wheel 14 to a distance from the optical axis 7 corresponding to the desired radius and swivelling the grinding wheel 1 which is to be profiled about the centre point of the desired circular arc profile. This swivelling movement is achieved by moving the axis of rotation of the carrier 13 into the optical axis and suitably displacing the gear unit 3 relative to the holder 5.

The profile grinding wheel 14 preferably has the same radius over the entire width of its peripheral surface.

For producing the desired profiles it is of great advantage in all procedures that with the optical projection profile forming grinding method an enlarged image of the point of engagement of the two grinding wheels is formed on the ground glass screen. It is thus possible to achieve extremely accurate adjustment of the grinding wheels and consequently the production of precision profiles such as are needed for use in optical projection form grinding machines of conventional type.

With the method and apparatus of the invention many profiles can be ground with only a single profiling wheel and there is thus no need to have a separate dressing roller for each profile.

WHAT I CLAIM IS: 1. A method of profiling a grinding wheel which is mounted on a carrier and is rotated by a drive, wherein the carrier is mounted on an optical projection form grinding machine in such a manner that the point of engagement of the grinding wheel which is to be profiled and of a profile grinding wheel of the machine lies in the region of the optical axis of an imaging system, and the mutual positions of the two grinding wheels are varied, by using the image of the point of engagement, in accordance with a desired profile to be ground on the grinding wheel.

2. A method according to Claim 1, for profiling a grinding wheel having a profile in the shape of an arc of a circle, wherein the grinding wheel which is to be profiled is positioned relative to the optical axis of the imaging system in such a way that the optical axis extends through the centre of the circular arc profile that is to be ground, the profile grinding wheel is rotatably mounted on a fixed axis in such a way that its active periphery is at a distance corresponding to the desired profile radius from the optical axis of the imaging system, and the carrier is swivelled about the optical axis of the imaging system relative to the projection form grinding machine.

3. Apparatus for carrying out the method of Claim 1 or Claim 2, comprising a carrier for holding a driven grinding wheel which is to be profiled, which carrier is mounted

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. of the wheel 14 runs along the desired curve on the ground glass screen. The profile grinding wheel 14 thus grinds the desired profile in the grinding wheel 1. In this way even complicated profiles can be ground with the greatest precision. In the method described the grinding wheel 1 which is to be profiled, is held in position during the grinding operation, while the profile grinding wheel 14 is moved in accordance with the profile which is to be ground. For the production of a profile having the shape of an arc of a circle the method described below is suitable. By adjusting the compound rest 12 the carrier 13 is adjusted to bring the axis of the swivel mounting of the arm 6 relative to the bearing plate 8, into coincidence with the optical axis 7. The gear unit 3 is moved relative to the holder 5 in such a way that the optical axis 7 passes through the grinding wheel 1 which is being profiled, at the centre point of the circular arc profile which is to be produced. The profile grinding wheel 14 is so adjusted that its peripheral surface at the height of the shaft 4 of the grinding wheel 1 is situated at a distance from the optical axis 7 corresponding to the radius of the circular arc profile which is to be ground. When the arm 6 and the grinding wheel 1 mounted thereon are now swivelled by way of a swivelling lever 20 about the axis of rotation coinciding with the optical axis 7, a circular arc profile is ground on the grinding wheel 1. The image formed on the ground glass screen 21 is shown in Figure 3. The optical axis is indicated on the screen for example, by the point of intersection A of two marking lines 2 and 23. The peripheral surface 24 of the profile grinding wheel 14 at a distance R, corresponding to the radius of the circular arc profile which is to be cut from the intersecting point A of the optical axis. The grinding wheel 1 which is to be profiled is so arranged that, with the aid of its carrier, it can be turned about the centre point of the circular arc profile which is to be ground. In Figure 3 the grinding wheel 1 is shown on the left-hand side in solid lines in a first swivelled position and on the right-hand side in broken lines in a second swivelled position. It can thus be seen that when the grinding wheel 1 is swivelled about the axis of rotation of the carrier, which coincides with the optical axis 7, there will be ground on the grinding wheel 1 a circular arc profile whose radius depends solely on the distance R between the profile grinding wheel 14 and the optical axis 7. By this method it is thus possible, using a single profile grinding wheel 14, to grind circular arc profiles of different radii in a simple manner by adjusting the profile grinding wheel 14 to a distance from the optical axis 7 corresponding to the desired radius and swivelling the grinding wheel 1 which is to be profiled about the centre point of the desired circular arc profile. This swivelling movement is achieved by moving the axis of rotation of the carrier 13 into the optical axis and suitably displacing the gear unit 3 relative to the holder 5. The profile grinding wheel 14 preferably has the same radius over the entire width of its peripheral surface. For producing the desired profiles it is of great advantage in all procedures that with the optical projection profile forming grinding method an enlarged image of the point of engagement of the two grinding wheels is formed on the ground glass screen. It is thus possible to achieve extremely accurate adjustment of the grinding wheels and consequently the production of precision profiles such as are needed for use in optical projection form grinding machines of conventional type. With the method and apparatus of the invention many profiles can be ground with only a single profiling wheel and there is thus no need to have a separate dressing roller for each profile. WHAT I CLAIM IS:

1. A method of profiling a grinding wheel which is mounted on a carrier and is rotated by a drive, wherein the carrier is mounted on an optical projection form grinding machine in such a manner that the point of engagement of the grinding wheel which is to be profiled and of a profile grinding wheel of the machine lies in the region of the optical axis of an imaging system, and the mutual positions of the two grinding wheels are varied, by using the image of the point of engagement, in accordance with a desired profile to be ground on the grinding wheel.

on an optical projection form grinding machine in such a manner that the point of engagement of the grinding wheel which is to be profiled and of a profile grinding wheel lies in the region of the optical axis of an imaging system of the machine and an image of the point of engagement is formed on the ground glass screen of the projection form grinding machine.

4. Apparatus according to Claim 3, for profiling a grinding wheel having a profile in the shape of an arc of a circle, wherein the carrier is swivellable about the optical axis of the imaging system, the grinding wheel which is to be profiled is held on the carrier for displacement relative to the optical axis and is so adjusted that the optical axis extends through the centre point of the circular arc profile which is to be produced, and the profile grinding wheel is so positioned that its active peripheral surface is at a distance from the optical axis corresponding to the desired radius of the circular arc profile.

5. Apparatus according to Claim 4, wherein the profile grinding wheel has the same radius over its whole periphery.

6. Apparatus according to any one of Claims 3 to 5, wherein the carrier is mounted on the projection form grinding machine for displacement at right angles to the optical axis.

7. Apparatus according to any one of Claims 3 to 6, wherein the carrier is mounted on a workpiece rest of the projection form grinding machine.

8. Apparatus according to any one of Claims 3 to 7, wherein a swivel mounting for the carrier has a hollow bearing shaft so that light rays of the optical imaging system pass through the shaft.

9. A method of profiling a grinding wheel substantially as herein described with reference to the accompanying drawings.

10. Apparatus for profiling a grinding wheel substantially as herein described with reference to the accompanying drawings.