JPH07319524A - Numerical controller for grinder - Google Patents

Abstract

PURPOSE:To finish a grindstone with equal surface accuracy without damaging the shape of the grindstone by deciding a correcting course while including shape elements as well with a position calculated by an overrun position arithmetic means as the end point or start point of a correcting operation. CONSTITUTION:A correction program preparing part 4 reads out a grind-stone shape element TDM of a grindstone shape storage part 5, prepares a dressing program DP according to that grindstone shape element TDM and transmits it to a correcting course control part 6 together with the read grindstone shape element TDM. On the other hand, an overrun position arithmetic part 9 calculates overrun positions OPA and OPB based on blocks DPA and DPB of the dressing program DP respectively stored in buffers A and B and transmits them to the correcting course control part 6. When it is necessary to change the dressing program DP, the correcting course control part 6 changes the dressing program DP while referring to the overrun positions OPA and OPB and transmits it to a program control part 2' as a dressing program IC.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a numerical control device for a grinding machine (hereinafter referred to as NC device for a grinding machine) having a function of correcting a grinding wheel (hereinafter referred to as a grinding wheel) for grinding a workpiece (hereinafter referred to as dressing). Name).

[0002]

2. Description of the Related Art Generally, a grinding machine is equipped with a correction tool (diamond) for correcting a grindstone. FIG.
FIG. 4 is a plan view showing an example of a grinder (hereinafter referred to as an NC grinder) equipped with such a NC device for a grinder, in which a grindstone base 81 having a grindstone 86 mounted on a bed 80 moves vertically in the drawing. It is attached so that it can move in any direction (hereinafter, this drive shaft is referred to as the X-axis), and similarly, the table 8 is mounted on the bed 80.
2 can move to the left and right in the drawing (hereinafter this drive axis
It is attached to the shaft). A work 83 and a headstock 85 for fixing and driving the work 83 and a tailstock 84 are attached on the table 82, and a diamond holder 73 having a correction tool attached is attached to the headstock 85. NC configured in this way
In the grinding machine, the grindstone is movable in two axis directions orthogonal to the work, and the correction tool is also movable in two axis directions orthogonal to the grindstone.

Generally, in the grinding process, the sharpness of the grindstone deteriorates every time the work is ground, and therefore dressing is performed regularly for the purpose of maintaining the sharpness.

FIG. 8 is a block diagram showing an example of a conventional NC apparatus for a grinding machine which controls the NC grinding machine as described above. Program control unit 2 is a command CD from operation panel 1.
The machining program PM stored in the machining program storage unit 3 is read according to P, and when the read machining program PM contains a dressing command DCD, the dressing command DCD is sent to the correction program creating unit 4.
The correction program creating unit 4 reads out the grindstone shape element TDM which expresses the grindstone shape by the dressing command DCD from the grindstone shape storage unit 5, creates the dressing program DP, and sends it to the program control unit 2. If the dressing command DCD does not exist, the program control unit 2
The read machining program PM is the program P as it is.
If the dressing command DCD is sent to the program analysis unit 10 as C, the dressing program DP sent from the correction program creation unit 4 is sent to the program PC.
To the program control unit 2. Program analysis unit 1
0 is the program P sent from the program control unit 2.
C is analyzed and data PA for axis drive is created.
Send to 1. The axis drive unit 11 controls the drive axis according to the data PA.

FIG. 9 shows an example of a cross-sectional shape including the grindstone axis of the grindstone (hereinafter referred to as a grindstone shape). FIG. And an example of a dressing program for each shape element based on the grindstone shape of FIG. The grindstone shape of FIG. 9 is a taper straight line a (P1-P
2), straight straight line b (P2-P3), taper straight line c
(P3-P4), each of which corresponds to this, in the storage data table of FIG. 10, the horizontal coordinate is Z and the vertical coordinate is X, and the Z coordinate of the left end face in the grindstone shape of FIG. Is stored and data (shape type, start point position, end point position) corresponding to each shape element (a, b, c) forming the grindstone shape is stored in a coordinate system in which the bottom surface X coordinate is 0. . The correction program creating unit 4 sequentially reads out the shape elements from the storage data table, and sets the path traced from the start point to the end point of the shape element according to the shape type of the read shape element as the dressing program DP. The dressing program DP is created corresponding to each shape element as shown in FIG. 10, and its path (P1 → P
2 → P3 → P4) is shown in FIG. Here, the program in parentheses in FIG. 10 indicates that it is a program for positioning at the position of X20Z00 which is the starting point.

[0006]

FIG. 11 shows a corner portion P of FIG.
This is an excerpt of two parts, and when dressing the corner P2, the shape of the corner P2 becomes round due to the following delay of the machine. As a means for preventing this, as shown in FIG. 12, a point where the shape elements whose command values are adjacent to each other intersect (hereinafter referred to as an intersection)
There is a droop check function that stops the movement of the command until the machine catches up with the command value. In this case, it is possible to prevent the shape of the corner P2 from becoming round, but the roughness of the grindstone surface due to the change in the correction speed (hereinafter referred to as surface roughness)
Becomes uneven. The unevenness of the surface roughness directly changes the sharpness of the grindstone, which not only deteriorates the quality of the workpiece after machining (hereinafter referred to as the workpiece machining quality), but in some cases causes a shape error. . The present invention has been made from the above-mentioned circumstances, and an object of the present invention is to provide a numerical control device for a grinding machine that can finish the surface roughness of a grindstone uniformly without impairing the shape of the grindstone. is there.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and is a tangential line at the intersection of each shape element and the distance required for deceleration stop from the corrected feed speed and the stop. An overrun position calculating means for calculating a position (hereinafter referred to as an overrun position) separated by a distance required to reach the corrected feed speed from the state, and an intersection angle between adjacent shape elements are calculated, and from the calculated intersection angle It is determined whether or not the route for tracing the adjacent shape elements sequentially is the correction route, and when the route for tracing the adjacent shape elements is not the correction route, it is calculated by the overrun position calculating means. This is achieved by providing the position as the end point or the start point of the correction operation, and providing the correction path control means for determining the correction path from the end point, the start point and the shape element.

[0008]

In the present invention, the distance required for acceleration and deceleration on the tangent of the shape element forming the intersection when the crossing angle of the adjacent shape elements in the dressing corrects the corner as shown in FIG. Since the distant position is the end point or the start point of the correction operation, the corner shape is prevented from being rounded, and at the same time, the correction feed rate is constant while the correction tool contacts the grindstone and traces the shape element. The surface roughness of the grindstone is made uniform.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an example of an NC apparatus for a grinding machine that controls the NC grinding machine according to the present invention, corresponding to FIG. 8. The same parts are designated by the same reference numerals and the description thereof will be omitted.
The correction program creating unit 4 ′ reads out the grindstone shape element TDM from the grindstone shape storage unit 5, and reads out the read grindstone shape element T.
A dressing program DP is created in accordance with DM and is sent to the corrected path control unit 6 together with the read grindstone-shaped element TDM. The corrected route control unit 6 uses the dressing program D.
One block DPA of P is stored in the buffer A, and the next block DPB is stored in the buffer B.
1 of the dressing programs DP stored in the buffer A and the buffer B, respectively, if necessary, referring to DM
The blocks DPA and DPB are sent to the overrun position calculation unit 9. The overrun position calculation unit 9 determines the overrun position OP based on one block DPA and DPB of the dressing program DP stored in the buffer A and the buffer B, respectively.
A and OPB are calculated and sent to the corrected route control unit 6. When the corrected path control unit 6 determines that the dressing program DP needs to be changed, the corrected route control unit 6 refers to the overrun positions OPA and OPB sent from the overrun position calculation unit 9 to change the dressing program DP, and the dressing program IC Is sent to the program control unit 2 ′ via the corrected path control unit 6. The program control unit 2 ′ sends the dressing program IC sent from the corrected path control unit 6 to the program analysis unit 7.

With such a configuration, an example of the operation of the present invention will be described with reference to the flow charts of FIGS. 2 and 3, centering on the corrected path control unit 6 which is the main part of the present invention. When the dressing command DCD is included in the machining program PM read by the program control unit 2 ′, the correction path control unit 6 stores one block DPA of the dressing program DP received from the correction program creation unit 4 ′ in the buffer A. (Step S1). Dressing program D
It is determined whether P is finished (step S2). If it is finished, the process proceeds to step S12. If it is not finished, the next block DPB of the dressing program DP is set in the buffer B.
(Step S3). Next, in correspondence with the one block of dressing programs DPA and DPB stored in the buffer A and the buffer B, each grinding wheel shape element TD
The tangent line of M is obtained, and the intersection angle of the shape elements is calculated (step S4). FIG. 6 is a diagram for explaining the crossing angle, and the angle in the counterclockwise direction of the tangent to the block DPB of the buffer B is the crossing angle with the tangent of the shape element corresponding to the block DPA of the buffer A as a reference. In this case, the intersection angle is 225 degrees for both P2 and P3.

Next, it is judged whether or not the route for sequentially tracing the adjacent shape elements is the corrected route. A guarantee angle (usually 180 degrees) defined as a minimum angle for preventing rounding of corners is compared with the intersection angle (step S5). If the intersection angle is larger than the guarantee angle, the adjacent shape elements are It is determined that the route to be sequentially traced is not the correction route, and the process proceeds to step S6. If it is smaller, it is determined to be the route to sequentially trace the adjacent shape elements as the correction route, and the process proceeds to step S13. In step S6, the DP stored in the buffer A and the buffer B is stored.
Overrun position OPA is calculated based on the coordinate values of the intersections based on A and DPB, the distance required for deceleration stop from the corrected feed speed calculated in advance, and the distance required to accelerate from the stopped state to the corrected feed speed. , OPB are calculated (step S6). Next, the end point of the block DPA of the dressing program DP stored in the buffer A is changed from the calculated overrun position OPA (step S7), and the start point of the block DPB of the dressing program DP stored in the buffer B is changed from the overrun position OPB. (Step S8), a block for performing a connecting operation is inserted to change the program to an overrun operation (step S8).
9). FIG. 7 illustrates the overrun operation at P2, and is a diagram in which the corner portion P2 of FIG. 4 is extracted. In the figure, between P2-P5 (OPA), P2-P6 (OP
The distance between B) is the distance required for deceleration stop from the corrected feed speed, and the distance required for accelerating from the stopped state to the corrected feed speed, based on the acceleration / deceleration characteristics of the shaft drive unit 11 and the normally used corrected feed speed. The value L calculated in advance so as to be the above is used. End point position P2 of block of buffer A
Is the position P5 on the tangent line of the shape element corresponding to the buffer A.
To (OPA), the starting point position P2 of the block of the buffer B is set to the position P6 (O on the tangent of the shape element corresponding to the buffer B).
PB), a block connecting P5-P6 is generated, and the program is changed to an overrun operation program. It is assumed that the connecting operation is performed by fast-forwarding one axis at a time. In the example of FIG. 4, a block for fast-forwarding by P-P5 to P7 by Z-axis single-axis and a block at P7-P6 by fast-forwarding by X-axis single axis are generated. .

The dressing program IC changed to the overrun operation is transferred to the program control unit 2 '(step S10). FIG. 5 shows the changed dressing program IC for each shape element. The program in the parenthesis shows the program for positioning at the position of X20Z00 which is the starting point. Step S1
1 stores the block DPB stored in the buffer B in the buffer A for the overrun operation determination at the next intersection.
Transfer to. The operations from step S2 to step S11 are repeated until it is determined in step S2 that the dressing program DP is completed. On the other hand, when it is determined in step S2 that the dressing program DP is completed, the block DPA of the buffer A is finally transferred to the program control unit 2 ′ as the dressing program IC. (Step S12). As described above, steps S2 to S11 are repeated until it is determined that the machining program PM is finished, and finally step S12 is performed.
All processing ends.

FIG. 4 shows a dressing path changed according to the present invention.

[0014]

As described above, according to the NC device for a grinding machine of the present invention, it is possible to determine whether the operation of tracing adjacent shape elements or the overrun operation in dressing according to the intersection angle of the adjacent shape elements of the grindstone. In the case of overrun motion, the position on the tangent line of the shape element forming the intersection and at least the distance required for acceleration / deceleration is set as the end point or start point of the correction operation, and the dressing is performed so as to pass through the end point or start point. Since the path is changed, it is possible to prevent the corners of the grindstone from being rounded, and to make the surface roughness of the grindstone uniform, which can improve the quality of the workpiece and prevent the occurrence of shape errors. You can

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of an NC device for a grinding machine of the present invention.

FIG. 2 is a flowchart for explaining the operation of the main part of the NC device for a grinding machine of the present invention.

FIG. 3 is a flowchart explaining the operation of the main part of the NC device for a grinding machine of the present invention, which is a continuation of the flowchart shown in FIG.

FIG. 4 is a first diagram illustrating a specific operation example of the NC device for a grinding machine of the present invention.

FIG. 5 is a second diagram illustrating a specific operation example of the NC device for a grinding machine of the present invention.

FIG. 6 is a third diagram illustrating a specific operation example of the NC device for a grinding machine of the present invention.

FIG. 7 is a fourth diagram illustrating a specific operation example of the NC device for a grinding machine of the present invention.

FIG. 8 is a block diagram showing an example of a conventional NC device for a grinding machine.

FIG. 9 is a first diagram illustrating a specific operation example of a conventional technique.

FIG. 10 is a second diagram illustrating a specific operation example of the conventional technique.

FIG. 11 is a third diagram illustrating a specific operation example of the conventional technique.

FIG. 12 is a fourth diagram illustrating a specific operation example of the conventional technique.

FIG. 13 is a plan view showing an example of a conventional NC device for a grinding machine.

[Explanation of symbols]

 1 Operation Panel 2, 2'Program Control Section 3 Machining Program Storage Section 4, 4'Correction Program Creation Section 5 Grindstone Shape Storage Section 6 Corrected Path Control Section 7 Buffer A 8 Buffer B 9 Overrun Position Calculation Section 10 Program Analysis Section 11 Axis drive

Claims (1)

[Claims] 1. A grindstone shape storage means for storing a plurality of shape elements forming a sectional shape including a grindstone axis of a grindstone wheel for grinding a workpiece, and the grindstone can be modified according to the shape element. In a numerical control device for a grinding machine, a position on the tangent line at the intersection of each of the shape elements and at a distance more than the distance required for deceleration stop from the corrected feed speed and the acceleration from the stopped state to the corrected feed speed is calculated. An intersection angle between the run position calculating means and the adjacent shape elements is calculated, and it is determined from the calculated intersection angle whether or not a route for sequentially tracing the adjacent shape elements is set as a correction route, and the adjacent shape is determined. When the route for tracing the element is not the correction route, the position calculated by the overrun position calculating means is set as the end point or the start point of the correction operation, and the end point, the start point. And a correction path control means for determining a correction path from a shape element.