JPH04315571A - Instituting method for grinding condition - Google Patents

Abstract

PURPOSE:To automatical institute a grinding condition without need of skilfulness of an operator or massive preliminary data. CONSTITUTION:Allowable values for at least either of normal line component force or tangent line component force of grinding resistance and their ratio are instituted, the normal line component force and the tangent line component force are measured during working, and their ratio is computed. When the ratio is under the allowable value, at least the allowable value of either of the normal line component force or the tangent line component force is compared with the measured value to institute a grinding condition, and when the ratio is over the allowable value, dressing is executed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for automatically setting and changing grinding conditions.

0002

BACKGROUND OF THE INVENTION In recent years, the use of NC in grinding machines has progressed, but in many cases, grinding conditions are input interactively into an NC device each time machining is performed.

[0003] To reduce the input work of such grinding conditions,
In order to achieve more advanced automation, for example,
In Publication No. 53562, when the operator inputs the dimensions and materials of the grindstone and workpiece, the NC device sets the grinding conditions based on the grinding condition selection data for various materials inputted in advance. .

0004

[Problems to be Solved by the Invention] However, with the above-mentioned conventional technology, a huge amount of basic experimentation is required to determine the selection data to be input into the NC device in advance, and high reliability of the selection data is guaranteed. Otherwise, there is a problem in that desired grinding results may not be obtained. In addition, once the grinding conditions are selected, they are fixed until the grinding of the workpiece is completed, but because the sharpness of the grindstone changes from time to time during the grinding process, the grinding conditions are not necessarily maintained at the appropriate state. There were also problems. An object of the present invention is to provide a method for automatically setting grinding conditions without preparing selection data that requires extensive basic experiments, and also taking into account the sharpness of the grindstone.

[0005]

[Means for Solving the Problems] The above-mentioned problems are the tolerance of at least one of the normal component force and the tangential component force of the grinding resistance, and the bicomponent force that is the ratio of the normal component force and the tangential component force. Set the allowable value of the ratio, measure the above normal component force and tangential force during machining, calculate the above two-component force ratio, and if the two-component force ratio is within the allowable value, the normal component force and tangential force Set grinding conditions by comparing the allowable value of at least one of the component forces with the measured value,
If the bicomponent force ratio exceeds the allowable value, the problem can be resolved by performing dressing.

[0006]

[Function] The ratio of the normal component force Fn and the tangential component force Ft of the grinding resistance (bicomponent force ratio: Fn/Ft) is almost unaffected by the grinding conditions and is determined almost solely by the sharpness of the grindstone. , which changes over time as shown in FIG. On the other hand, the normal force Fn and the tangential force Ft are strongly influenced by the grinding conditions, and as shown in Fig. speed). Also, the normal component force Fn
Even if the grinding conditions are constant, the tangential force Ft increases as the sharpness of the grindstone deteriorates, so the normal force Fn and the tangential force Ft include the effects of both the grinding conditions and the sharpness of the grindstone. ing. Therefore, by first comparing the bicomponent force ratio with a preset allowable value αl, it is possible to know the degree of deterioration of the sharpness of the grindstone, and from this it is possible to determine whether dressing is necessary. Next, the bicomponent force ratio is the allowable value α
Since the sharpness of the grindstone is ensured if it is less than l, the grinding conditions can be selected by comparing at least one of the normal component force Fn and its allowable value Fnl, or the tangential force Ft and its allowable value Ftl.

That is, at least one of the maximum permissible normal component force Fnl and the maximum permissible tangential component force Ftl determined by the motor capacity, the rigidity of the grinding machine, etc. is set, and the normal component force Fn and the maximum permissible tangential component force Ftl during grinding are set. By setting the grinding conditions (grinding wheel depth of cut, feed amount, table speed) so that at least one of the tangential force Ft is close to the above-mentioned allowable value Fnl or Ftl, grinding can be performed automatically with maximum efficiency. It can be performed. At this time, even if the bicomponent force ratio is within the allowable value, the sharpness of the grindstone will gradually decrease as shown in Figure 3, but it is important to periodically perform comparisons with the allowable value as described above during grinding. As a result, the grinding conditions can be changed while taking into account the reduction in the sharpness of the grindstone, so the grinding process can always be performed under appropriate grinding conditions that are within the maximum capacity of the grinder.

[0008]

[Example] Below, FIGS. 1 and 2 show an example of the present invention.
This is explained by: FIG. 1 shows a conceptual diagram when the present invention is applied to a surface grinder. In the figure, 1 is a bed. Reference numeral 2 denotes a table, which is held on the bed 1 so as to be slidable in a direction perpendicular to the plane of the paper in the figure, and is driven by a motor 3. 4 is attached to table 2 with a chuck,
A workpiece 5 is held on the upper surface. A column 6 is held on the bed 1 so as to be slidable in the left and right directions in the figure, and is driven by a motor 7. Reference numeral 8 denotes a grinding wheel head, which is held by the column 6 so as to be slidable in the vertical direction in the figure, and is driven by a motor 9. Reference numeral 10 denotes a grindstone shaft, which is rotatably held by the grindstone head 8 and driven by a motor 11. 12 is a grindstone, which is attached to the tip of the grindstone shaft 10. A vibration sensor 13 is fixed to the grinding wheel head 8. 14 is a vibration meter. A current sensor 15 is connected to the motor 11. 16 is an ammeter. Reference numeral 17 denotes an NC device, which is comprised of a setting circuit, a program storage circuit, an arithmetic circuit, a control circuit, and the like. The NC device 17 includes motors 3, 7, 9, 11.
A program for controlling the relative movement between the workpiece 5 and the grinding wheel 12, information regarding the dimensions of the grinding wheel and the workpiece, initial grinding conditions, tolerance value αl of the two-component force ratio, tolerance of the normal component force. Input the value Fnl etc. Here, the initial grinding conditions are temporary grinding conditions until the grinding resistance is measured and the grinding conditions are automatically set, and since they are likely to change quickly, they should be set on the safe side. Bye. Although not shown, a dressing device is attached to the top of the table 2.

In the above configuration, when the start button (not shown) is pressed, the workpiece 5 is started by a command from the NC device 17.
The grinding wheel 12 and the grinding wheel 12 perform a relative movement, and the grinding process is started according to the initial grinding conditions. At this time, the normal component force F of the grinding resistance
n is measured as the vibration amplitude detected by the vibration sensor 13, and the tangential force Ft is measured as the consumed current detected by the current sensor 15, and is input to the NC device 17. The NC device 17 corrects and changes the initial grinding conditions based on this measured value and sets them to optimal values. Note that the grinding condition to be changed here is the grinding wheel depth of cut, and the other conditions are fixed (for example, grinding wheel circumferential speed =
1500m/min, table speed = 20m/min,
Feed amount = grinding wheel width x 1/3).

The processing procedure will be explained below with reference to FIG. 2. First, when the grinding process is started, the grinding wheel 12 is
The normal component force Fn and the tangential component force Ft are measured every time one pass is made in the length direction, and are input to the NC device 17. NC device 1
7, when the grindstone 12 makes one pass in the width direction of the workpiece 5, the average value Fnm of the normal component force Fn and the average value Ftm of the tangential component force during this pass are calculated, and from this, the bicomponent force ratio α is α=Fnm/ F
Find it as tm. Next, compare the preset allowable value αl of the bicomponent force ratio with α, and if α>αl, the sharpness of the grinding wheel has decreased, so dressing is performed, and then the normal component force Fn and the tangential Returning to the step of measuring component force Ft. on the other hand,
If α≦αl, the sharpness of the grindstone is good, so the ratio β of the average value of normal component force Fnm and the allowable value Fnl of normal component force
is determined as β=Fnl/Fnm. Then, ti=k・β・ti−1 (i=1, 2, 3, etc.) with respect to the previously set grindstone depth of cut ti−1
However, it is changed as follows: t0: Initial setting grindstone depth of cut k: Safety factor (k≦1). By repeating this, the average value Fnm of the normal component force gradually approaches the permissible value Fnl of the normal component force. If the predetermined finished dimension has not been reached, the process returns to the step of measuring the normal component force Fn and the tangential component force Ft, and when the predetermined finished dimension is reached, the grinding process is finished.

According to this embodiment, the grinding conditions can be automatically set so that grinding is performed near the maximum limit of the grinding machine's capacity while monitoring the bicomponent force ratio of the grinding resistance, resulting in extremely high efficiency. At the same time, it is possible to realize grinding processing, and at the same time, there is an effect that selection data for grinding conditions, which requires a huge amount of basic experiments as in the conventional technology, is not required. Also,
Even if the bicomponent force ratio is within the allowable value, the sharpness of the grinding wheel will gradually decrease, but since grinding conditions can be set that takes into account the decrease in sharpness of the grinding wheel, it is possible to always set the optimal grinding conditions. It's also effective.

Note that the measurement of the grinding resistance and the setting of the grinding conditions are not limited to those described above, and may be performed as follows. (1) In the above embodiment, the grinding resistance was measured using the vibration of the grinding wheel head 8 and the power consumption of the motor 13, but it is also possible to directly measure the grinding resistance by attaching the workpiece 5 to the chuck 4 via a piezoelectric element, strain gauge, etc. or by other means. (2) In the above example, the normal component force Fn was used to change the cutting depth of the grinding wheel, but the tangential component force Ft may also be used, or both the normal component force Fn and the tangential component force Ft may be used. It's okay. (3) In the above embodiment, by changing the cutting depth of the grinding wheel,
Although other grinding conditions are fixed, the table speed and feed amount may be changed, or the grinding wheel depth of cut, table speed, and feed amount may be changed in combination. (4) In the above embodiment, the grinding conditions were changed using the ratio β between the average value Fnm of the normal component force and the allowable value Fnl of the normal component force, but the average value Fnm of the normal component force The difference between Fnl and the allowable value Fnl of the normal component force may be used, or other values that can evaluate the difference between the two may be used. (5) In the above embodiment, the allowable value αl of the bicomponent force ratio is N
Although it was set in advance in C device 17, dressing was performed at the same time as the grinding process started, and the value was automatically set as the value obtained by multiplying the bicomponent force ratio measured immediately after dressing by a predetermined coefficient a (a>1). You can also do this. (6) In the above embodiment, the normal component force and the tangential component force were obtained as average values during one pass of the grindstone 12 in the width direction of the workpiece 5. Position of(
For example, it may be determined as a value when passing through the central position in the width direction.

[0013]

[Effects of the Invention] As detailed above, according to the present invention, the grinding conditions are adjusted so that the grinding process is performed near the maximum capacity of the grinding machine while monitoring the sharpness of the grindstone using the bicomponent force ratio of the grinding resistance. Since it can be set automatically, it has the effect of realizing extremely highly efficient grinding. Another advantage is that selection data for grinding conditions, which requires extensive basic experiments as in the prior art, is no longer required. Furthermore, since grinding conditions can be set in consideration of the sharpness of the grindstone, it is possible to always perform grinding under optimal grinding conditions.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram when the present invention is applied to a surface grinder.

FIG. 2 is a flowchart showing a procedure for automatically setting grinding conditions.

FIG. 3 is an explanatory diagram showing how the bicomponent force ratio changes.

FIG. 4 is an explanatory diagram showing changes in normal component force and tangential component force of grinding resistance.

[Explanation of symbols]

5. Workpiece, 11. Motor, 12. Grindstone, 13.
・Vibration sensor, 14... Vibration meter, 15... Current sensor,
16... Ammeter, 17... NC device.

Claims (2)

[Claims] [Claim 1] A tolerance value for at least one of the normal component force and tangential component force of the grinding resistance, and a tolerance value for the bicomponent force ratio, which is the ratio of the normal component force and the tangential component force, are set, and the tolerance value is set during machining. Measure the above normal component force and tangential component force and calculate the above bicomponent force ratio, and if the bicomponent force ratio is within the allowable value, calculate the allowable value of at least one of the normal component force and the tangential component force. and a measured value to set the grinding conditions, and if the bicomponent force ratio exceeds an allowable value, dressing is performed. 2. The method for setting grinding conditions according to claim 1, wherein the normal component force is measured by vibration, and the tangential component force is measured by current consumption or power consumption of the motor.