JPH04310368A - Grinding control method - Google Patents

Abstract

PURPOSE:To improve the accuracy of dimension, generating line shape and cylindricity and get up the cutting speed by controlling the sizing point of the workpiece dimension predictively from the intermittent measured data, and controlling the oscillating position and speed of a wheel spindle stock so as to attain contact with the whole face of the workpiece at a grinding completing point. CONSTITUTION:The target dimension of a work 3 and the measured dimension measured by an in-process gauge 1 during grinding are inputted into a comparing arithmetic circuit 9 from a target dimension setting circuit 10. The time reaching the target dimension is predictively computed by the circuit 9 on the basis of the dimension data taken in through a sizing signal read circuit 8 in the state of the inner diameter dimension being intermittently measured in succession interlockingly with the oscillating action of a wheel spindle stock 5. Upon reaching this time instant, a feed motor 7 is reversed by a cutting control circuit 12 so as to retreat a cross slide 4. Concurrently, when the work dimension enters a range close to the target dimension, the wheel spindle stock 5 is stopped at its advance end by an oscillation control circuit 11. The dimension accuracy is thereby improved.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a grinding control method for oscillating a grindstone with respect to a workpiece, measuring the dimensions of the workpiece in conjunction with the oscillation of the grindstone head, and grinding the workpiece to a fixed size. The present invention relates to a grinding control method applied to internal grinding of small annular parts.

0002

[Prior art] In internal grinding of small annular parts, the grindstone head is oscillated in the traverse direction relative to the workpiece, the workpiece dimensions are automatically measured in conjunction with this grindstone oscillation, and the grinding operation is stopped when near the fixed size. Intermittent in-process measurement grinding methods are known. In the case of small workpieces, it is not possible to have both the grinding wheel and the in-process gauge in contact with the grinding surface of the workpiece at the same time due to dimensional constraints, so the grinding wheel head and in-process gauge are linked together to oscillate and the wheel head retreats. When this happens, an in-process gauge is inserted into the workpiece to perform sizing measurements. In this method, workpiece grinding is finished when the intermittent measurement data exceeds a preset sizing value. Therefore, since grinding cannot be completed at the true sizing point, improvement in dimensional accuracy is limited. On the other hand, in order to improve dimensional accuracy, the workpiece dimensions are predictively controlled using a measurement signal during intermittent in-process sizing measurement, and this predictive control signal is used to control the retraction of the measuring device and the cutting stop of the grindstone. A device has been proposed (for example, Japanese Patent Publication No. 53-14797). In this method, the measuring device retreats before the set size, no dimension measurements are performed after that, and the grindstone is removed from the workpiece at the time when the predicted size is set, and the machining cycle ends.

0003

[Problem to be solved by the invention] The above-mentioned Special Publication Publication No. 53-1
The grinding method shown in Publication No. 4797 processes a measurement signal of in-process sizing measurement to generate a sizing prediction control signal,
This control signal controls the cut into the workpiece, so
Improved dimensional accuracy can be expected compared to conventional methods that do not perform sizing prediction. However, since this method cuts up at any position in the oscillation stroke depending on the timing of the sizing prediction signal, the contact position between the workpiece and the grinding wheel in the traverse direction is not constant at the end of workpiece grinding, and the inclination of the grinding wheel varies due to deflection of the grinding wheel shaft. As a result, the cylindricity accuracy of the grinding surface of the workpiece deteriorates. In addition, it is not guaranteed that the grinding wheel and workpiece will come into contact with the entire surface when grinding the workpiece, and if the cutting speed is increased to increase efficiency, if grinding is finished when the grinding head oscillation retreats, the grinding wheel will be in contact with the entire surface of the workpiece. There is a problem that a difference in diameter occurs where the workpiece is not in contact with the workpiece, and a step is created in the shape of the workpiece generatrix.

Therefore, the present invention controls the grinding wheel head oscillation position at the grinding completion point (when the cutting head retreats) to always be at the grinding wheel head forward end, thereby improving the cylindricity accuracy and generatrix shape accuracy. The object of the present invention is to provide a grinding control method that can increase cutting speed while ensuring work precision and improve efficiency.

[0005]

[Means for Solving the Problems] According to one aspect of the present invention, in a grinding control method in which a grinding wheelhead is oscillated and a work piece is intermittently measured in-process at the retreating end of the oscillation, the size is determined from intermittent measurement data. Predictive calculation is performed, and when the workpiece dimensions are within a certain range of the sizing point based on the intermittent measurement data, the grinding wheel head is oscillated and stopped at the forward end of oscillation, and the workpiece cutting head is moved back at the predicted sizing point. A grinding control method is provided.

According to another aspect of the present invention, in a grinding control method in which a grinding wheelhead is oscillated and a workpiece is intermittently measured in in-process at the retreating end of the oscillation, the workpiece dimensions are determined from intermittent measurement data by predictive calculation. The time required to reach the sizing point is predicted, the oscillation speed is controlled so that the grindstone head reaches the oscillation advance end at the predicted time, and the workpiece cutting head is moved back at the predicted sizing point. A grinding control method is provided.

[0007]

[Operation] In the present invention, the predicted time until the workpiece dimension reaches the target dimension is calculated based on the measurement data of intermittent in-process measurement, and when the predicted time arrives, the cutting table is retreated and the grinding wheel head is turned. Either stop the oscillation of the grinding wheel head at the forward end of the oscillation, that is, when the grinding wheel and workpiece are in full contact, or control the oscillation speed based on this predicted time so that the grinding wheel oscillates at the predicted fixed size. Make sure it is at the forward end. Therefore, in any case, at the end of grinding, the grinding wheel is in full contact with the workpiece, and the position of the working surface of the grinding wheel relative to the workpiece is constant, so there is no step in the workpiece generatrix shape, there is no variation in the inclination of the grinding wheel, and the dimensions Accuracy and tilt accuracy are improved.

[0008]

Embodiments Next, embodiments of the present invention will be explained with reference to the drawings. 3 and 4 are cross-sectional views showing the positional relationship between the workpiece 3 and the grindstone 2 during internal grinding of the workpiece by intermittent in-process sizing measurement. The grindstone 2 is inserted into the workpiece 3 from one side, and has a forward end (Fig. 4) and a backward end (Fig. 3).
Internal grinding is performed while oscillating between. In conjunction with this grindstone oscillation, the measurement tip of the in-process gauge 1 is inserted into the workpiece 3 at the oscillation retreat end of the grindstone 2 to measure dimensions, and the measurement tip is pulled out of the workpiece 3 at the oscillation advance end. The cut in the workpiece 3 is made by moving the workpiece 3 in a direction perpendicular to the grindstone 2. If the cutting feed of the workpiece 3 is retracted at the timing shown in Fig. 3, that is, it is rounded up, there will be a step on the inner surface of the workpiece at the part where the grinding wheel 2 hits, as shown in Fig. 5, but when it is rounded up in the state of hitting the entire surface as shown in Fig. 4. In this case, there will be no step, and the accuracy of the generatrix shape of the workpiece will improve. In addition, the grinding resistance acting on the grinding wheel 2 is different between the state shown in Fig. 3 and the state shown in Fig. 4, and therefore there is a difference in the deflection of the grinding wheel shaft due to the grinding resistance. Therefore, if the position of the grinding wheel at the time of cutting is not constant, the cylindricity of the workpiece will vary. comes out. In view of this point, the present invention controls the grinding wheel 2 so that it is in a state where it touches the entire surface during sizing, that is, it cuts up at the oscillation advance end.

FIG. 1 is a block diagram of an internal grinding machine showing an embodiment according to one aspect of the present invention. The target workpiece size from the target size setting circuit 10 and the workpiece size measured by the in-process gauge 1 during grinding are input to the comparison/calculation circuit 9. Now, while the in-process gauge 1 is intermittently measuring the inner diameter of the workpiece 3 intermittently in conjunction with the oscillation operation of the grinding wheel head 5, the sizing signal is read in through the sizing signal reading circuit 8. The comparison/calculation circuit 9 predicts and calculates the time when the workpiece size will reach the target size based on the workpiece size data, and when this time is reached, the cutting control circuit 12 reverses the cutting motor 7 and the cutting table 4 to retreat. In parallel, when it is determined that the measured workpiece size is within a certain range (described later) close to the target size, the grindstone head 5 is controlled by the grindstone head oscillation control circuit 11 at the forward end of oscillation. After that, the grindstone head 5 is not moved back. Therefore, the grindstone 2 continues to grind the workpiece 3 by plunge cutting until the predicted time, and the workpiece 3 is cut up in this state. In this way, in the present invention, predictive control is performed on the cutting head retraction time, so dimensional accuracy is improved, and since the grinding wheel head 5 is always at the oscillation forward end at the point where grinding is completed, the accuracy of the generatrix shape of the workpiece and the cylindrical shape are improved. accuracy is improved.

The control flow of the above operation will be explained using FIG. 2. After the grinding cycle is started, dimensional measurement data is collected using the in-process gauge 1 in the state shown in FIG. 3 (step 13). The comparison/calculation circuit 9 calculates the workpiece dimension change A during one round trip of oscillation (step 14), and it is determined whether the workpiece dimension is close to the target dimension or not. When it is determined that the workpiece dimension is close to the target dimension, the specific In other words, the remaining grinding amount ≦
When it is determined that the voltage has reached 1.5A (step 15),
Prediction timer (remaining grinding amount/A) x oscillation 1
The round trip time is set (step 16). Here, the remaining grinding amount≦1.5A will be explained. It takes 1/2 oscillation time from the dimensional measurement data by the in-process gauge 1 to the oscillation advance end, that is, from the state shown in FIG. 3 to FIG. 4, and the dimensional change occurs accordingly. Therefore, the remaining grinding amount at the time of dimension measurement is (0.
5 to 1.5) x (dimensional change amount A during one reciprocation of oscillation). That is, if the remaining grinding amount is smaller than 0.5×A, the target dimension is exceeded at the oscillation advance end. Furthermore, if the remaining grinding amount exceeds 1.5×A, the machining allowance when the oscillation advance end is reached is 1.0×A or more. In this case, the predicted time to reach the target dimension is longer than one oscillation round trip time. In order to improve dimensional accuracy, the stopping time at the forward end of oscillation should be within one oscillation time, and for this reason, the range that is judged to be close to the target dimension is the remaining grinding amount ≦ 1 as described above. ．．
Let it be 5×A. After setting the prediction timer, stop the oscillation at the forward end of the oscillation (step 19).
), cutting is stopped and retreated upon expiration of the prediction timer (steps 17 and 18).

Next, an embodiment of the second aspect of the present invention will be described. In this second mode, unlike the above-mentioned example in which the wheel head oscillation is stopped at the point where the grinding is completed, the oscillation operation is continued without stopping the oscillation, and the wheel head oscillation reaches the forward end just at the point where the grinding is completed. The speed of the grinding wheelhead oscillation is controlled so that the In other words, the speed pattern setting circuit 20 in FIG. 1 causes the grindstone head oscillation to come to the forward end at the time when the cutting head is retracted when the comparison/calculation circuit 9 determines that the workpiece size is close to the target size. A new speed pattern is set, and the whetstone head motor 6 is operated via the whetstone head oscillation control circuit 11 to control the oscillation of the whetstone head 5. As a result, the cutting table 4
At the grinding completion point where the grinding wheel moves backward, the grinding wheel head 5 is at the forward end of oscillation, and grinding is completed with the grinding wheel 2 in full contact with the workpiece 3, improving the generatrix shape accuracy and cylindricity accuracy of the workpiece. is brought about.

0012

As explained above, according to the present invention, in internal grinding by intermittent in-process sizing measurement, the sizing point of the workpiece dimension is predictively controlled from the intermittent measurement data, and the grinding head oscillation position or oscillation By controlling the grinding speed and ensuring that the grinding wheel always makes full contact with the workpiece at the point where grinding is completed, the dimensional accuracy, generatrix shape accuracy, and cylindricity accuracy of the workpiece are improved, and the finishing cutting speed is increased. This also has the effect of achieving the target accuracy and improving efficiency.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an internal grinder according to an embodiment of the present invention.

FIG. 2 is a diagram showing a control flow of the grinding control method according to the first aspect of the present invention.

FIG. 3 is a sectional view showing the state of the retreating end of the grindstone oscillation in intermittent in-process sizing measurement grinding.

FIG. 4 is a cross-sectional view showing the state of the grindstone oscillation advance end in intermittent in-process sizing measurement grinding.

FIG. 5 is a sectional view showing a state in which a step is formed on the grinding surface of the workpiece at the retreating end of the grindstone oscillation during internal grinding of the workpiece.

[Explanation of symbols]

1 In-process gauge 2 Grinding wheel 3 Workpiece 4 Cutting head 5 Grinding wheel head 8 Sizing signal reading circuit 9 Comparison/calculation circuit 10 Target dimension setting circuit 11 Grinding head oscillation control circuit 12 Cutting control circuit 20 Speed pattern setting circuit

Claims (2)

[Claims] Claim 1: A grinding control method in which a grinding wheel head is oscillated and a work piece is intermittently measured in in-process size at the retreating end of the oscillation, in which a workpiece size prediction calculation is performed from intermittent measurement data, and the workpiece size is determined from the intermittent measurement data. A grinding control method characterized by stopping the oscillation of the grindstone head at the oscillation advance end when the workpiece is within a certain range of the sizing point, and retracting the workpiece cutting head at the predicted sizing point. [Claim 2] A grinding control method in which a grinding wheel head is oscillated and a work piece is intermittently measured in in-process at the retreating end of the oscillation, wherein the time required for the workpiece dimension to reach the sizing point by predictive calculation from intermittent measurement data is provided. A grinding control method characterized by predicting, controlling the oscillation speed so that the grinding wheel head comes to the oscillation advance end exactly at the predicted time, and retracting the workpiece cutting head at the predicted sizing point.