JPH0453668B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a surface grinding device for surface grinding a workpiece by table traverse.

<Prior art> For example, when surface grinding a stepped workpiece as shown in Fig. 2 with a stepped grinding wheel, the machining distance is 3 from t1 to t3.
When grinding by traversing the table, the grinding resistance (tangential resistance) varies greatly depending on the difference in machining allowance.

In conventional surface grinding equipment of this type, the table traverse speed is only one speed, so the traverse speed that corresponds to the maximum machining stock is determined, and the table is traversed throughout the entire process at this traverse speed to grind the workpiece. ing. Therefore, there is a problem that the cycle time becomes long.

On the other hand, in general, in cylindrical grinding, adaptive control that detects the shaft power acting on the grindstone shaft and controls the grinding speed so that this shaft power is always constant is also put into practical use. When applied to surface grinding, when the machining allowance varies slightly even in the same grinding part, such as a black scale workpiece, there is a problem that the speed changes frequently even in the same grinding part, and no improvement in surface roughness can be expected. be.

<Object of the Invention> An object of the present invention is to provide a surface grinding device that can significantly shorten the cycle time without significantly changing the tangential resistance.

<Structure of the Invention> In order to achieve the above object, the present invention includes a storage means for storing the diameter dimensions of the large diameter part and the small diameter part of the grinding wheel, and the machining allowance dimension of the stepped machined surface, and stores these diameter dimensions and machining allowance dimension. The large-diameter part and the small-diameter part of the grinding wheel each start grinding the stepped surface of the workpiece based on the calculation means, and the calculation means calculates a plurality of positions at which the grinding width changes. The apparatus is equipped with a feed control means that converts and controls the traverse speed of the table at a plurality of calculated positions so as to slow the traverse speed in accordance with an increase in the grinding width.

<Example> Hereinafter, an example of the present invention will be described based on the drawings.

In FIG. 1, reference numeral 10 indicates a bed of a numerically controlled surface grinding device, and a table 11 is mounted on the bed 10 so as to be able to traverse in the left and right direction. The feed is controlled via a feed screw. A column 13 is installed behind the bed 10, and a whetstone head 14 of this column 13 is mounted so as to be movable in the vertical direction. The feed is now controlled. A grinding wheel 16 is supported on the grinding wheel head 14 so as to be rotatable around a horizontal axis perpendicular to the direction of movement of the table 11, and is rotationally driven by a grinding wheel drive motor (not shown). The grinding wheel 16 has a stepped structure including a large diameter portion 16a with a grinding wheel diameter D1 and a small diameter portion 16b with a grinding wheel diameter D2, and a workpiece mounted on the table 11 can be fixed in a predetermined position by one traverse of the table 11. It is designed to be surface ground to size.

Next, the shape of the workpiece W and the relationship between the workpiece W and the grinding wheel 16 will be described based on FIGS. 2 and 3. The upper surface of the workpiece W to be surface ground consists of two high and low surfaces with a predetermined step, and a small diameter portion 1
The machining allowance is width b1 and thickness t1 for the high finished surface W1 ground by 6b, and the width b2 and thickness is for the low finished surface W2 ground by the large diameter part 16a.
The machining allowance of t2 is further increased by the large diameter part 16 at the step part.
Width b3 and thickness t3 (t3=t1+
A machining allowance of t2) is provided for each.

A workpiece W having such a shape is placed at 1 on the table 11.
When grinding a surface to a specified dimension with multiple traverses,
As the table 11 traverses, the machining allowance t3 first begins to be ground by the large diameter portion 16a of the grinding wheel 16, and at this time the grinding width becomes b3. Next, machining allowance t2
part begins to be ground by the large diameter part 16a of the grinding wheel 16, and the grinding width increases to b2+b3. Finally, the machining allowance t1 part begins to be ground with the small diameter part 16b of the grinding wheel 16,
The grinding width is also the total width of the workpiece W (b1+b2+b3)
increases to In this way, the grinding conditions change in three stages as the machining allowance increases.

FIG. 4 shows a control circuit for controlling the surface grinding device configured as described above, in which the central processing unit 21 in the numerical control device 20 is constituted by a microprocessor,
A memory 22, a data input device 23, and an interface 24 are connected to the central processing unit 21.
Each servo motor 1 is connected to this interface 24.
Drive unit 2 drives each of 2 and 15.
5 and 26 are connected.

The large diameter portion 16 of the grinding wheel 16 is stored in the memory 22.
Data on the diameters D1, D2 of the small diameter portion 16b, machining allowances t1, t2, t3 of the workpiece w, etc. are inputted by the data input device 23 and stored in a predetermined storage area. The memory 22 also contains data on distances X01 and X02 from the center position 0 of the grinding wheel 16 to the machining original position P0 and machining completion position P4, as well as the position P1 where the large diameter portion 16a of the grinding wheel 16 starts grinding the machining allowance t3. , Similarly, the large diameter portion 16a is the machining allowance t2
Each data of a position P2 at which grinding of the section starts and a position P3 at which the small diameter section 16b of the grinding wheel 16 starts grinding the machining allowance t1 section is stored in a predetermined storage area.
The respective grinding start positions P1, P2, P3 are determined by internal calculation from the respective data of the grinding wheel diameters D1, D2 and machining allowances t1 to t3. starting position p1
The distance L1 to is calculated by the following calculation formula.

L1=√(12)2-3 ² and the grinding start position from the center position 0 of the grinding wheel 16
Distances L2 and L3 to P2 and P3 are found. In this case, the above-mentioned t1 to t3 are set somewhat larger in consideration of the variation in the machining allowance.

Next, a flowchart for surface grinding the workpiece W mounted on the table 11 is shown in FIG. Note that S1 to S20 in the figure indicate each step of the flowchart.

When the start of grinding is commanded, the process completion flags FLG1 to FLG7 set for each grinding process are set in S1.
It is determined whether all the grinding processes have been completed based on the state of the flag, and if not, the process to be performed next is determined in accordance with the state of the flag in the next S2, and the process in S3 to S9 is performed. Transition to either.

Since all flags FLG1 to FLG7 have been reset at the start of grinding, the process first shifts to S3. However, in such S3, memory 2
The central processing unit 21 subtracts the position data L1 of the machining allowance t3 part grinding start position P1 from the position data X01 of the machining original position P0 stored in 2, and calculates the rapid traverse movement amount.
X1 is calculated. Next, in S10, the amount of movement X1
The number of pulses corresponding to
It is traversed in rapid traverse from P1 to the grinding start position P1 for the machining allowance t3. Next, in S11, the flag FLG1 is set and the process returns to S1, and the process proceeds to S4 based on the process determination as described above.

In S4, the grinding start position P1 for the machining allowance t3
The position data L2 of the grinding start position P2 for the machining allowance t2 is subtracted from the position data L1 of the first grinding feed movement amount.
X2 is calculated, and in S12 -
Pulses are distributed to the drive unit 25 at a first grinding feed rate F1. This results in table 11
The traverse speed is changed to the first grinding feed rate F1 to start surface grinding with a machining allowance t3, and then S13
Set flag FLG2 with .

Similarly, in S5, the position data L3 of the grinding start position P3 for the machining allowance t1 is subtracted from the position data L2 of the grinding start position P2 for the machining allowance t2 to obtain the second grinding feed movement amount X3, and in S14, the movement amount A pulse corresponding to X3 is distributed to the drive unit 25 at a second grinding feed rate F2 that is slower than F1, and in S6, the position data L3 of the grinding start position P3 of the machining allowance t1 and the position data X0 of the grinding completion position P4 are distributed to the drive unit 25.
are added to obtain the third grinding movement amount X4,
In S16, the − pulse according to the amount of movement X4 is
It is distributed to the drive unit 25 at the third grinding feed rate F3, which is slower than the third grinding feed rate F3. This results in table 11
The traverse speed of machining allowance t2 part grinding start position P2
The machining allowance is converted to the second grinding feed rate F2 at
The t2 and t3 parts are ground, and the machining allowance t1 part is the grinding start position.
At P3, it is further converted to the third cutting feed speed F3,
The machining allowances t1, t2, and t3 are ground.

By controlling the traverse speed of the table 11 in accordance with changes in the machining allowance acting on the grinding wheel 16 in this way, the traverse speed can be controlled within the allowable tangential resistance limit without increasing fluctuations in tangential resistance during grinding. be able to increase it.

When the table 11 is traversed to the grinding completion position P4, the relief amount Y1 is then set at S7.
The + pulse corresponding to
Travel amount X5 (X5=X01+X02=X1+X2+
X3+X4) is distributed to the drive unit 25 at a rapid traverse speed F0, and the table 11 is returned to the machining original position P0, and at S9, a - pulse corresponding to the relief amount Y1 is distributed to the drive unit 26. The grinding wheel head 14 is then lowered by a certain amount to complete the grinding cycle.

Note that since each of the grinding start positions P1, P2, and P3 changes as the diameter of the grinding wheel 16 decreases due to dressing, the grinding wheel diameter data stored in the memory 22 is rewritten every time the grinding wheel diameter changes. , each time the grindstone diameter decreases by a certain amount, the data of P1, P2, and P3 are updated based on the grindstone diameter.

In the above embodiment, the dimensions of the machining allowance are directly stored, but the finished dimensions and material dimensions of the workpiece are stored in the memory, and the machining allowance is calculated by calculating these finished dimensions and material dimensions. In this way, the machining allowance may be stored indirectly.

Further, in the above embodiment, the stepped grinding wheel 16
Although an example has been described in which the two high and low surfaces of the workpiece W are ground by surface grinding, it goes without saying that the present invention can also be applied to surface grinding of more complex shapes such as tooth profile shapes.

<Effects of the Invention> As described above, in the present invention, the grinding start position in the traverse direction is calculated and determined from the relationship between the grinding wheel diameter and the workpiece machining allowance, and the traverse speed of the table is changed from the rapid traverse speed at this grinding start position. Since the configuration is configured to convert the feed rate into the grinding feed rate, the table traverse speed can be adjusted to the grinding conditions within the range of allowable tangential resistance, even for workpieces with stepped machining surfaces that have large differences in machining allowance. This has the effect of significantly shortening the cycle time compared to conventional ones.

Moreover, according to the present invention, since the traverse speed is maintained constant in the same grinding section, it also has the effect of improving surface roughness compared to adaptive control where the feed speed fluctuates frequently. be given

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a plan view of a surface grinding device, FIGS. 2 and 3 are diagrams showing the relationship between the grinding wheel and the workpiece, and FIG. 4 is a diagram showing the control circuit. The block diagram shown in FIG. 5 is a flowchart showing the operation of the central processing unit in FIG. 11...Table, 12...Servo motor, 1
4... Grindstone head, 15... Servo motor, 16...
Grinding wheel, 20... Numerical control device, 21... Central processing unit, 22... Memory, 23... Data input device, 25, 26... Drive unit.

Claims (1)

[Claims] 1. A workpiece having a stepped surface is mounted on a table that can be traversed in the horizontal direction, and a grinding wheel with a large diameter portion and a small diameter portion for grinding the stepped surface is mounted horizontally at right angles to the traverse direction of the table. A surface grinding device rotatably supported around an axis includes a storage means for storing the diameter dimensions of the large diameter portion and the small diameter portion of the grinding wheel, and the machining allowance dimension of the stepped machined surface; Based on this, each of the large diameter part and the small diameter part of the grinding wheel starts grinding the stepped surface of the workpiece, and the calculation means calculates a plurality of positions at which the grinding width changes. A surface grinding device comprising a feed control means for converting and controlling the traverse speed of the table at a plurality of calculated positions so as to slow the traverse speed in accordance with an increase in the grinding width.