JPH07227758A - Method and device for controlling surface grinding machine - Google Patents

Abstract

PURPOSE:To enable physical quantities useful in controlling a grinding machine to be measured with accuracy by measuring the physical quantities only while grinding is actually being performed, thus allowing for a state in which grinding is not performed (air is cut) because a grinding wheel and a workpiece are distant from each other at longitudinal and horizontal stroke ends. CONSTITUTION:In traverse grinding, a grinding wheel 8 is moved in +Y direction by a predetermined amount (y) each time a workpiece 5 moves half of its stroke in X direction, and after the grinding wheel 8 has reached a position Y3, it is moved in -Y direction by (y) each time the workpiece 5 moves half the stroke in X direction. Similarly, the grinding wheel 8 is made to reciprocate between Y0 and Y3. After the left end of the workpiece 5 indicated by the full line has moved in -X direction from the position X0 (proximity switch 10a is on) and the right end of the workpiece 5 indicated by the two-dot chain line has been moved to the position X2 (proximity switch 11a is on), machining is started on the arrival of the left end of the workpiece 5 at the position X1, and is finished on the arrival of the right end at the position X1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface grinding machine control method and apparatus.

[0002]

2. Description of the Related Art In order to automatically determine the dressing time of a grinding wheel, Japanese Patent Laid-Open No. 4-315571 detects physical quantities representing grinding phenomena such as grinding resistance, wheel axis motor current, vibration, and the like. When the combined value exceeds the preset limit value, dressing is performed. In addition, in order to control the grinding condition to an optimum value according to the grinding state during the grinding process, Japanese Patent Laid-Open No. 4-3546
In No. 73, the grinding condition is changed when the change rate of the grinding resistance exceeds a preset allowable value.

[0003]

However, in all of the above-mentioned prior arts, the physical quantity for controlling the operation of the grinding machine is continuously measured. ◆ Generally, in the surface grinder,
At the stroke ends in the front-rear direction and the left-right direction, the grinding wheel and the workpiece are separated from each other, and a state in which grinding is not performed (air cut state) occurs. Therefore, the above-mentioned measured values of the prior art also include values at the time of air cutting, and it is not possible to obtain an accurate physical quantity, and an error occurs in the determination of the dressing timing and the processing condition change timing. An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a control method and apparatus capable of accurately controlling the operation of the surface grinder including the dressing timing and processing conditions.

[0004]

SUMMARY OF THE INVENTION The above-mentioned problems are solved by detecting at least one of the front and rear stroke ends and the left and right stroke ends of the surface grinder, and detecting a predetermined time, distance, and machining. The problem can be solved by controlling at least one of the operation of the grinder and the processing condition by a physical quantity representing a grinding phenomenon detected in any of the relative numbers of movements of the object and the grinding wheel.

[0005]

Since only the physical quantity during the actual grinding process is measured, the change in the physical quantity can be accurately obtained.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The case where the present invention is applied to the determination of dressing timing will be described below. FIG. 1 shows a surface grinder. The left side is a front view and the right side is a side view. Further, FIG. 2 is a flowchart of the operation procedure. ◆ In Fig. 1, 1 is a bed. A table 2 is slidably held on the bed 1 in the direction of arrow X.
A magnet chuck 3 is fixed to the table 2 via a piezoelectric element 4. Reference numeral 5 is a workpiece, which is attached to the magnet chuck 3. 6 is a column, bed 1
It is slidably held upward in the direction of arrow Y. A spindle head 7 is held by the column 6 slidably in the direction of arrow Z. Reference numeral 8 denotes a grinding wheel, which is attached to the tip of a wheel shaft (not shown) rotatably held by the spindle head 7. 9a and 9b are guides, and bed 1
It is fixed to. Proximity switches 10a, 11a, 10b, and 11b are held by guides 9a and 9b so as to be movable in the directions of arrows X and Y, respectively. 12a, 12
Reference numeral b denotes a dog, which is fixed to the table 2 and the column 6 so as to be located at the center of the moving range thereof. 1
A dresser 3 is fixed to the table 2. An NC device 14 controls a drive system (not shown) for the table 2, the column 6, and the spindle head 7, and other drive sources. The piezoelectric element 4 and the proximity switches 10a and 10b described above are used.
The signal from is input to the NC device 14. Further, the NC device 14 has a timer T and a timer t built therein.
Times T ₁ , T ₂ , T ₃ , regarding movement in the front-back direction, which will be described later,
The times t ₁ and t ₂ , the sampling interval Δt, and the allowable value Fmc relating to the movement in the left-right direction can be set in advance. The NC device 14 also calculates the grinding resistance and stores the calculation result.

Now, the times T ₁ , T ₂ , T ₃ , t ₁ and t ₂ when the workpiece 5 is traverse ground will be described with reference to FIG. Note that FIG. 3 is a schematic representation of the positional relationship between the workpiece 5 and the grinding wheel 8. ◆ Now, the position of the grinding wheel 8 at the start of grinding is Y ₀ , and the workpiece 5 is X.
Grinding wheel 8 for a predetermined y each time it reciprocates 1/2 way
Is moved in the + Y direction. Then, when the grinding wheel 8 reaches the position of Y ₃ , the work piece 5 is 1 / X in the X direction, contrary to the above.
Every time the vehicle makes two round trips, it is moved in the -Y direction by the above y. In the same manner, the grinding wheel 8 is reciprocated between Y ₀ and Y ₃ . At this time, the entire width of the grinding wheel 8 is involved in the grinding process from the position Y _{1 to} the position Y ₂ . ◆ Also, the left end of the workpiece 5 shown by the solid line moves from the position X _{0 in} the −X direction,
Assuming that the right end of the work piece 5 indicated by the chain double-dashed line is moved to the X ₂ position, the grinding wheel 8 begins to machine the work piece 5 when the left end of the work piece 5 reaches the X ₁ position. Workpiece 5
Machining ends when the right end of the mark comes to the position of X ₁ . The position of X ₁ is the axis of the grinding wheel 8. Further, the workpiece 5 and the grinding wheel 8 are positioned so that the centers of Y ₀ and Y ₃ are the centers of the workpiece 5 in the Y direction. Then, the workpiece 5 moves so that the right end is X ₂ and the left end is X _0, and when the right end is at the position X ₂ , the proximity switch 11a is turned on, and when the left end is at the position X ₀ , the proximity switch 10a is turned on. To do. ◆ the above case, time T ₁ is Y ₁ grinding wheel 8 from Y ₀
The time T ₂ is set to be shorter than the time required for the grinding wheel 8 to move from Y ₀ to Y ₂ . Further, the time T ₃ is the time required for the grinding wheel 8 to move from Y ₀ to Y ₃ . Further, if the workpiece 4 is moved in the -X direction, the time t ₁ is longer than the time the left end of the workpiece 5 is moved from X ₀ to X _1, time t ₂ is a right end X ₁ of the workpiece 5 Set shorter than the time it takes to pass.

The operation will be described below with reference to FIG. The grinding operation is executed by a program registered in the NC device 14 in advance. ◆ First, when the program starts, the grinding wheel 8 moves to the position of the dresser 13 and dressing is performed (step 100). When dressing is complete, the normal grinding cycle causes workpiece 5
Are ground (step 110). Proximity switch 1
When 0b detects the dog 12b, the timer T is reset and the time counting is started (steps 120 and 130). When the time T of the timer T reaches a preset time T ₁ , the counter i is reset (steps 140 and 150). Next, 1 is added to the counter i (step 160), and when the proximity switch 10a detects the dog 12a, the timer t
Is reset and clocking is started (steps 170, 1)
80). When the time t of the timer t reaches a preset time t ₁ , the counter j is reset (step 190,
200). Next, 1 is added to the counter j (step 210). Then, each time the minute sampling time Δt elapses from the time t ₁ , the time t is set to t = t ₁ + j · Δt (step 220), and it is confirmed that the time t has not reached t ₂ (step 230). When the time t has not reached the time t ₂ , the grinding resistance F (j) is measured (step 240). Then, this measurement is repeated until the time t reaches a preset t ₂ . When the time t has reached the time t _2, the average value calculated to F (i) of this period of grinding force (step 250) and repeats until this time T reaches T ₂ (step 260). Then, when the time T ₂ is reached, the average value Fm of the grinding resistance per one pass in the front-rear direction is obtained (step 270). Then, the grinding process is continued until the time T reaches T ₃ (step 275). Time T
When T reaches T ₃ , the average value Fm of the grinding resistance is compared with the allowable value Fmc of the grinding resistance (step 280). And Fm
Is smaller than Fmc and reaches the finishing dimension, the grinding process is terminated, and if the grinding process is continued, step 110
Then, the grinding process is continued again (step 290). If Fm is larger than Fmc, the grinding process is terminated if the finished dimension has been reached, and if the grinding process is to be continued, the process returns to step 100 to perform dressing, and the grinding process is continued again (step 300). ◆ Here, when continuing the grinding process (steps 290 and 300), since Y ₃ is at a position symmetrical to Y ₀ with respect to the center of the work piece 5 as described above, the Y ₃ position moves in the -Y direction. Even when it is used, T ₁ and T ₂ can be used as they are. In the above embodiment, the signals from the proximity switches 10a and 10b on the right end side of the table 2 and the rear end side of the column 6 are used, but the proximity switches on the left end side of the table 2 or the front end side of the column 6 are used. The signals from 11a or 11b may be used, or both signals may be processed individually.

By the way, FIG. 4 shows an example of measurement of the grinding resistance during traverse grinding, and a part of it is shown enlarged. As can be seen from the figure, even under the same grinding conditions, there is a difference in grinding resistance between forward movement (when moving in the + Y direction) and backward movement (when moving in the -Y direction). This is because the portions of the grinding wheel that are mainly involved in the grinding process are the front end side and the rear end side, respectively, during the forward movement and the backward movement, and the grinding processing is performed at different portions. Similar to the above, in the left-right direction, up-cutting and down-cutting occur alternately when moving to the left (when moving in the -X direction) and when moving to the right (when moving in the + X direction). However, there is a difference in grinding resistance between left and right. Therefore, the physical quantity in only one direction of the lateral movement and / or the longitudinal movement, or the physical quantity in each direction may be used individually. ◆ Furthermore, other physical quantities such as the current value of the grindstone shaft motor may be used instead of the grinding resistance to judge the dressing time, or multiple physical quantities such as the ratio of the normal resistance to the tangential resistance may be used. You may use the thing which combined. Although the grinding resistance measurement range is limited by the time after the signal is received, the measurement range may be limited by the distance or the number of movements after the signal is received. Furthermore, in the above embodiment, an example of determining the dressing timing has been shown, but the control target is not limited to this, and dressing conditions, grinding conditions, etc. may be controlled.

[0010]

As described above, according to the present invention, since the physical quantity is measured only during the actual grinding process, the physical quantity for controlling the grinding machine can be accurately measured. There is an effect that can be.

[Brief description of drawings]

FIG. 1 is a front view and a side view showing a configuration of an embodiment of the present invention.

FIG. 2 is a flowchart showing an operation procedure.

FIG. 3 is a diagram for explaining times T ₁ , T ₂ , T ₃ , t ₁ and t ₂ .

FIG. 4 is an example of measurement record of grinding resistance.

[Explanation of symbols]

3: Workpiece,
4: Piezoelectric element 8: Grinding wheel, 10a, 10b, 11a, 11
b: proximity switch 12a, 12b: dog,
14: NC device

Claims (2)

[Claims] 1. A surface grinder detects at least one signal from front and rear stroke ends and right and left stroke ends, and a predetermined time and distance after the signal is detected and a relative distance between a workpiece and a grinding wheel. A control method for a surface grinding machine, characterized in that at least one of an operation of the grinding machine and a processing condition is controlled by a physical quantity representing a grinding phenomenon detected at any one of the number of movements. 2. A means for detecting at least one signal of front and rear stroke ends and a left and right stroke ends of a surface grinding machine, a predetermined time and distance from the time when the signal is detected by the detecting means, a workpiece and a grinding wheel. And a means for measuring any one of the number of relative movements with and a means for measuring a physical quantity representing a grinding phenomenon, and detecting at least one of the front and rear stroke ends and the left and right stroke ends, Of the operation and processing conditions of the grinder, the physical quantity representing the grinding phenomenon detected in any one of the above-mentioned predetermined time and distance after detecting the signal and the relative number of times of movement of the workpiece and the grinding wheel. A control device for a surface grinding machine, which controls at least one of the above.