JP2816487B2 - Wheel shape correction device for spherical grinding machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a so-called dressing device for a grindstone shape correction device of a spherical grinding machine for performing spherical processing of a lens or the like using a cup-shaped grindstone.

<< Background Art >> As shown in FIG. 1, a spherical grinding machine using a cup-shaped grindstone makes a rotating cup-shaped grindstone 1 contact an oblique surface of a work 2 and slowly rotates the work 2 on the surface. Is ground into a spherical surface. The grindstone unit 3 that rotationally drives the cup-shaped grindstone 1 includes a tilting frame 4 that tilts and can be fixed around a tilting axis P (a direction perpendicular to the paper surface of FIG. 1) orthogonal to the rotation center axis W of the work 2 in the Z-axis direction. (In a direction parallel to the grinding wheel axis G) and an X-axis direction (a direction orthogonal to the grinding wheel axis G and the tilt axis P). When machining the work 2, the top of the work 2 is positioned so as to contact the edge 1a of the cup-shaped grindstone 1 on the extension of the tilt axis P, and the cup-shaped grindstone 1
And the tilt angle of the tilt frame 4 determine the curvature of the spherical surface to be machined.

In the illustrated apparatus, in order to accurately position the edge 1a of the cup-shaped grindstone on the extension of the tilt axis P, a Z-axis motor 5 for moving and positioning the grindstone unit 3 in the Z-axis direction and an X-axis for moving and positioning in the X-axis direction It has a motor 6. In a spherical grinder controlled by NC, the Z-axis motor 5 and the X-axis motor 6
Is controlled by the NC device 7.

FIG. 5 shows the relationship between the cup-shaped grindstone 1 and the work 2 when machining is performed normally. The edge 1a of the arc-shaped cross section of the cup-shaped grindstone 1 is one point ( Contact). When the edge 1a of the cup-shaped grindstone is worn and becomes in a state shown in an exaggerated manner in FIG. 6, the edge 1a of the cup-shaped grindstone and the work 2 come into contact with each other in a belt shape and are processed as shown in FIG. The surface roughness and spherical accuracy of the work 2 are reduced, and a ring-shaped diamond 8 is generated at the center of the processed surface, resulting in defective processing. So, to avoid such a situation,
The edge 1a of the cup-shaped grindstone must be regularly shaped so that its precise arc cross section is maintained.

<< Prior Art >> Dressing of a grindstone of a cylindrical grinding machine or an internal grinding machine is usually automatically performed by a dressing device provided in a grinding device. However, the cup-shaped grinding wheel of the spherical grinding machine has an arc-shaped cross section, and the radius of the arc of the edge changes depending on the curvature of the work surface of the work, the width of the grinding wheel, etc. It is the fact that dressing is performed by a grindstone maker.

《Problems to be solved by the invention》 For this reason, the user must prepare a large number of grinding wheels, and must replace the grinding wheel every time the grinding wheel wears out. It is difficult, and there is a problem that it takes time and trouble to attach and detach the grindstone when replacing the grindstone.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a spherical grinding machine which has a built-in dressing device capable of accurately shaping the arc cross section of the edge of a grindstone and can automatically dress a cup-shaped grindstone.

<< Means for Solving the Problems >> The grindstone shape correcting device of the present invention includes the tilting frame 4 for tilting the grindstone axis G with respect to the rotation center axis W of the work 2, and includes the cup-shaped grindstone 1. A grindstone unit 3 for rotating and driving the cup-shaped grindstone is driven by a Z-axis motor 5 and an X-axis motor 6 controlled by an NC device 7 to form a grindstone shaft G.
In a spherical grinding machine having a structure moved and positioned in a direction parallel to the grinding wheel axis and a direction perpendicular to the grinding wheel axis G and the tilt axis P, the tip of the spherical surface is tilted on the tilting frame 4 separated from the tilt axis P by a predetermined distance in the X-axis direction. A dress grindstone 11 having a pin point is rotatably provided around a dress grindstone axis D parallel to the grindstone axis G, and a dressing grindstone drive motor 12 for rotating the dress grindstone 11 around the axis is provided. 6 in conjunction with each other to control the grinding unit 3 with a radius r
A circular movement commanding means 21 for moving along a + R arc locus is provided.

The circular movement command means 21 is constituted by a program of the NC device 7, and can be realized by a program similar to a cutter feed control program when turning a spherical surface by an NC lathe. Note that r and R are the radius of the tip of the dressing grindstone 11 and the radius of the arc of the edge 1a of the cup-shaped grindstone, respectively, and r = 0 when a pinpoint grindstone is used.

<< Operation >> The dressing work of the cup-shaped grindstone 1 using the apparatus having the above configuration is performed as follows.

The NC device 7 instructs a dress operation every time a predetermined amount of grinding is performed. When the dressing operation is instructed, the NC device 7
Drives the X-axis motor 6 and the Z-axis motor 5 to move the edge 1a of the cup-shaped grindstone to the position of the tip of the dressing grindstone 11 and further advance it in the Z-axis direction by a predetermined cutting feed amount Δt.
Next, the grindstone unit 3 is caused to make a circular motion by the circular movement command means 21. During this time, the dress whetstone 11 and the cup-shaped whetstone 1 are driven to rotate. The NC device 7 has one
After the circular motion is performed, the Z-axis motor 5 and the X-axis motor 6 are driven to return the cup-shaped grindstone 1 to the home position. As a result, one dressing operation is completed, and the cup-shaped grindstone 1 shifts to processing of a workpiece.

Thus, the edge of the cup-shaped grindstone is
If 1a is shaped with dress whetstone 11, the edge of cup-shaped whetstone
The surface of the work 2 can always be machined into an accurate spherical surface without causing abrasion as shown in FIG. 6 in 1a. The above-mentioned dressing operation can be automatically performed by incorporating a predetermined program into the NC device 7 and periodically calling it, and the arc radius of the edge of the grindstone can be freely changed. Further, since it is not necessary to remove the grindstone 1 at the time of dressing, unattended automatic operation for a long time can be performed with one cup-shaped grindstone.

<< Embodiment >> FIG. 1 is a view schematically showing a spherical grinding machine provided with a grindstone shape correcting device of the present invention. Since the structure and operation of the main part of the spherical grinding machine shown in the figure have been described above, they are omitted here. Reference numeral 10 denotes a dressing unit fixed to the tilting frame 4 and includes a dressing grindstone 11 having a hemispherical tip, a motor 12 for driving the dressing grindstone rotation, and a casing 13 for supporting the dressing grindstone 11. The dressing wheel axis D is parallel to the wheel axis G of the cup-shaped wheel, and the dressing wheel axis D and the wheel axis G of the cup-shaped wheel are located in the same plane orthogonal to the tilt axis P.

The NC device 7 for controlling the Z-axis motor 5 and the X-axis motor 6 includes a dress operation command program 20, which moves the grindstone unit 3 from the origin position to the dress position. Movement command routine 22 for causing the grinding wheel unit 3 to advance by the set cutting amount,
Is moved along an arc trajectory.

FIG. 2 is a diagram showing the arc movement of the cup-shaped grindstone 1 in relation to the dressing grindstone 11, and the locus indicated by an imaginary line in the figure is the movement locus of the cup-shaped grindstone 1 and therefore of the grindstone unit 3. Is the radius r of the tip of the dress whetstone 11.
To the radius R of the cross section of the line 1a of the cup-shaped grindstone. As shown in FIG.
When a pinpoint grindstone is used as a point, the radius Q of the arc locus of the grindstone unit 3 is equal to the radius R of the arc of the edge 1a of the cup-shaped grindstone.

FIG. 3 is a flowchart showing an operation procedure when dressing the cup-shaped grindstone 1 is performed by the apparatus of the present invention.

When a dress operation is instructed during the continuous automatic machining of the workpiece 2, a rotation command is given to the dressing wheel drive motor 12, and Z
A movement command is given to the shaft motor 5 and the X-axis motor 6 to move the grindstone unit 3 to a position where the edge 1a of the cup-shaped grindstone 1 faces the dressing grindstone 11. Next, a cutting feed is instructed to the Z-axis motor 5 and a predetermined cutting amount Δt (for example, 1/10
0mm). Then, by the interlocking control of the Z-axis motor 5 and the X-axis motor 6 by the circular movement command routine 21, the grinding wheel unit 3 moves along the circular locus (the imaginary line in FIG. 2). By this movement, the edge 1a of the cup-shaped grindstone is moved to the fourth position.
As shown in the figure, it is brought into contact with the dress whetstone 11 while being fed by the dress amount Δt, and the edge 1a of the cup-shaped whetstone is shaped as shown by an imaginary line in the figure. Next, an origin return command is given to the Z-axis motor 5 and the X-axis motor 6 to return the grindstone unit 3 to the origin position. Then, the dressing grindstone 11 is stopped, the position of the grindstone unit 3 in the Z-axis direction at the processing position is corrected by Δt, and the dressing operation is completed.

Dress operation command program that commands this series of operations
20 is called every time a predetermined number of workpieces are processed or each time a predetermined time of processing is performed on the workpiece, and periodically shapes the edge 1a of the cup-shaped grindstone so that its shape is in a normal state. , Thereby ensuring that the machined surface of the workpiece 2 is machined into an accurate and smooth spherical surface.

<< Effects of the Invention >> As described above, according to the apparatus of the present invention, it is possible to automatically shape the arc shape of the edge of the cup-shaped grindstone, and
The dress operation can be performed by incorporating a predetermined dress operation program into the NC unit and calling this dress operation program periodically, so that the shape of the edge of the cup-shaped grindstone can always be maintained in an accurate arc-shaped cross section. Therefore, accurate spherical machining of the workpiece can be assured, long-time unmanned operation of the spherical machining of the lens surface and the like is possible, and the time required for attaching and detaching the grindstone is saved, so that the spherical grinding machine can be used. The operating rate also improves.

[Brief description of the drawings]

1 to 4 show one embodiment of the present invention.
FIG. 1 is a diagram schematically showing the configuration of the apparatus, FIG. 2 is an explanatory diagram of a dress operation, FIG. 3 is a flowchart of a dress operation,
FIG. 4 is an enlarged view showing the relationship between the cup-shaped grindstone and the dress grindstone. FIG. 5 is a diagram showing a machining state with a normal cup-shaped grindstone, FIG. 6 is a diagram showing a machining state with a worn cup-shaped grindstone, and FIG. 7 is a machining of a workpiece machined with a worn cup-shaped grindstone. FIG. 8 is a diagram schematically illustrating a surface, and FIG. 8 is an explanatory diagram of a dressing operation when a pinpoint grindstone is used. In the figure, 1: cup-shaped whetstone, 2: work 3: whetstone unit, 4: inclined frame 5: Z-axis motor, 6: X-axis motor 7: NC device, 11: dress whetstone 12: dress whetstone drive motor 22: circle Movement command routine W: Work rotation center axis, P: Tilt axis G: Wheel axis, D: Dress wheel axis

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B24B 53/08

Claims (1)

(57) [Claims] An inclined frame (4) for inclining a grindstone axis (G) with respect to a rotation center axis (W) of a work (2), a cup-shaped grindstone (1), and a cup-shaped grindstone are provided. A grinding wheel unit (3) for rotating the wheel is driven by a Z-axis motor (5) and an X-axis motor (6) controlled by an NC device (7) in a direction parallel to the grinding wheel axis (G) and the grinding wheel axis (G). ) And a tilting axis (P), the tip of which is spherical or pinned on a tilting frame (4) at a predetermined distance in the X-axis direction from the tilting axis (P). A dressing grindstone (11), which is a point, is rotatably provided around a dressing grindstone axis (D) parallel to the grinding wheel axis (G), and a dressing grindstone drive motor (12) for rotating the dressing grindstone axis around the axis is provided;
Circular movement command means (21) for moving the grindstone unit (3) along an arc trajectory by interlocking and controlling the Z-axis motor (5) and the X-axis motor (6) is provided. A grinding wheel shape correction device for a spherical grinding machine.