JP2535598B2 - Machining load monitoring device considering the tool feed direction - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a machining load monitoring device capable of detecting a machining load of a machine tool and generating a machining control signal in consideration of a tool feed direction.

(Prior Art) FIG. 8 is a block diagram showing an example of a conventional machining load monitoring device, which amplifies a detection signal SA from a load detection sensor 1 such as a spindle load current sensor, an AE sensor, and a feed axis current sensor. A sensor signal detection unit 2 that filters the processing load signal SB and a threshold value registration unit 6 in which the upper limit value and the lower limit value SC of the threshold value for adaptive control are registered in advance.
And a comparison unit 3 that compares the value of the machining load signal SB from the sensor signal detection unit 2 with the upper limit value and lower limit value SC of the threshold value from the threshold value registration unit 6, and the comparison result from this comparison unit 3. When the processing load signal value is higher than the upper limit value by SD, the signal SE that lowers the processing feed speed to reduce the processing load is sent to the NC device 5
When the machining load signal value is less than the lower limit value, the signal SF for increasing the machining feed speed to increase the machining efficiency is output to the NC device 5.
And a processing control signal generation unit 4 for outputting to.

(Problems to be Solved by the Invention) In the processing load monitoring device described above, the processing load signal value from the sensor and the threshold value that is uniquely determined by the tool by determining the processing feed rate and the spindle rotational speed are set. Based on this, the processing load is monitored. The machining load signal value from this sensor is proportional to the machining amount per unit time for each tool, but may not be proportional to the actual machining load. In particular, in the case of cutting a three-dimensional shape with a ball end mill, it is difficult to detect an accurate processing load because, for example, the cutting speed is easy and the corner angle and the like change easily between the tip of the tool and the outer circumference of the tool. there were.

The present invention has been made under the circumstances as described above,
An object of the present invention is to provide a machining load monitoring device that takes into account the tool feed direction and that can monitor the machining load with high accuracy.

(Means for Solving the Problem) The present invention relates to a machining load monitoring device that generates a machining control signal by comparing a detected machining load value with a threshold value registered in advance. The above-mentioned object is to correct the threshold value by a correction coefficient based on the peripheral speed of the contact portion of the non-planar blade bottom with respect to the workpiece that changes depending on the machining feed direction of the rotary tool having the non-planar blade bottom. This is achieved by including a threshold value correction unit that compares the corrected threshold value with the processing load detection value.

(Operation) Since the machining load monitoring device considering the tool feed direction of the present invention corrects the threshold value according to the machining state, even if the machining load detection value includes an error, an appropriate machining control signal can be obtained. Is the one that can generate.

(Embodiment) FIG. 1 is a block diagram showing an example of a machining load monitoring device in which the tool feed direction of the present invention is added in correspondence with FIG. 8, the same components are designated by the same reference numerals, and description thereof will be omitted. To do. This machining load monitoring device includes a tool / work information registration unit 11 in which tool / work information SG such as tool type, tool diameter, and work material is registered in advance, and a tool / work from the tool / work information registration unit 11. Spindle speed from information SG and NC device 5,
A correction formula determination unit 12 that determines a formula SI for correcting the threshold value based on the machining condition information SH such as the machining feed speed, and NC
The correction value obtained by substituting each axial component SJ of the machining feed rate from the device 5 into the correction formula SI from the correction formula determination unit 12 is used as a coefficient, and the correction coefficient is determined from the threshold value registration unit 6. There is newly provided a threshold value correction unit 13 which outputs the upper limit value and the lower limit value SK of the threshold value corrected by multiplying the upper limit value and the lower limit value SC of the value to the comparison unit 3.

With such a configuration, an example of the operation will be described with reference to the flowchart of FIG. 2 in the case of processing the slope of the work shown in FIG. The NC device 5 confirms whether or not the processing is completed (step S1). When the processing is completed, all the processing is completed. If the machining is not completed, the correction formula determining unit 12 confirms whether or not the machining feed speed F ₂ in the Z-axis direction is 0 or more (step S2), and the machining feed speed F _{2 in the} Z-axis direction is not 0 or more. In this case, that is, when the tool goes up the slope as shown in FIG. 4, machining is performed in a portion where the tool peripheral speed is relatively fast as shown in FIG. When the correction formula of the formula (1) is determined and the machining feed rate F ₂ in the Z-axis direction is 0 or more, that is, when the tool goes down the slope as shown in FIG. 5, it is shown in FIG. As described above, since machining is performed in a portion where the tool peripheral speed is relatively slow and a heavy load is applied to the tool, the correction equation of the following equation (2) is determined.

However, C ₁ , C ₂ ; correction coefficients Fx, Fy, Fz; X, Y, Z components of machining feed rate k; constant (k >> 1) The correction formula (1) or (2 ) Is substituted with the axial direction components Fx, Fy, Fz of the machining feed rate from the NC device 5 (steps S3, S4) to obtain the correction coefficient C ₁ or C ₂ . Then, the upper limit value A ₁ or A ₂ and the lower limit value of the threshold value corrected by multiplying the upper limit value A and the lower limit value B of the threshold value from the threshold value registration unit 6 by the obtained correction coefficient C ₁ or C ₂ and B ₁ or B _2, the values a _1, B ₁ or a _2, B ₂ and comparison made to adaptive control and the processing load signal value comparison section 3 (step S5, S
6) Return to step S1 and repeat the above operation.

Since the upper limit value A ₁ and the lower limit value ₁ of the threshold value corrected by the correction coefficient C ₁ become high as shown in FIG. 4, when the adaptive control is performed, the machining feed speed becomes high as a whole. The upper limit of the correction by the correction coefficient C ₂ threshold A ₂
Since the lower limit value B ₂ and the lower limit value B ₂ become low as shown in FIG. 5, the machining feed rate becomes low as a whole when adaptive control is performed.

(Effects of the Invention) As described above, according to the machining load monitoring apparatus in which the tool feed direction of the present invention is added, the non-planar surface for the non-machined object that changes depending on the machining feed direction of the rotary tool having the non-planar blade bottom Since the machining load threshold is corrected based on the peripheral speed of the contact part of the blade bottom of, it is possible to monitor the machining load with high accuracy and to provide a processed product with high accuracy. It is possible to prevent accidents due to breakage of the.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a machining load monitoring device in which the tool feed direction of the present invention is added, FIG. 2 is a flowchart explaining an example of its operation, and FIGS. 3 to 7 are operations of the device of the present invention. FIG. 8 is a block diagram showing a concrete example for explaining the above, and FIG. 8 is a block diagram showing an example of a conventional machining load monitoring apparatus. 1 ... Sensor, 2 ... Sensor signal detection unit, 3 ... Comparison unit, 4 ... Processing control signal generation unit, 5 ... NC device, 6 ...
Threshold registration part, 11 ... Tool / work information registration part, 12 ...
... correction formula determination unit, 13 ... threshold value correction unit.

Claims (2)

(57) [Claims] 1. A machining load monitoring apparatus for generating a machining control signal by comparing a detected machining load value with a threshold value registered in advance, in a machining feed direction of a rotary tool having a non-planar blade bottom. The threshold value is corrected by a correction coefficient based on the peripheral speed of the contact portion of the non-planar blade bottom with respect to the workpiece to be changed by the threshold value, and the corrected threshold value is compared with the processing load detection value. A processing load monitoring device in which a tool feed direction is added, which is provided with a value correction unit. 2. A correction formula determining section for determining a correction formula for calculating the correction coefficient based on machining information conditions that change during machining and pre-registered tool / work information. A processing load monitoring device that takes into consideration the tool feed direction described in.