JPS6211983B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device that automatically detects chip disposability during cutting.

In recent years, unmanned operation of various machine tools has become extremely popular, and more recently, technological development has been actively carried out with the aim of increasing efficiency and precision.

In parallel with such technological development, there is a strong need to take effective measures to prevent work safety, variations in service life, etc. for cutting tools used in industrial machinery.

In particular, a requirement placed on tools for unmanned operation of industrial machinery is to break up chips generated during cutting into smaller pieces to improve their evacuation. For this reason, grooves or obstacles are provided in the tool shape to make it easier to break up the chips, but these are not sufficient. Therefore, if the chips are not broken up and long chips are produced, the safety of the work will be compromised, so it is desirable that the situation be made known to the operator as soon as possible. Therefore, there is a strong desire for a detection device for monitoring various chip processing conditions.

However, some of the conventional proposals have problems such as insufficient accuracy and some devices are complicated and expensive, and have not yet reached a satisfactory technical level.

In particular, it must be said that the automatic detection method for chip control, which greatly affects work safety and the quality of workpieces, is at a very low level.

An object of the present invention is to provide a device that can accurately and easily detect chip disposability.

A tool or machine tool during cutting generates vibration signals having various frequency components, as shown in FIG.

Therefore, as shown in FIG.
When rotating in the direction and cutting with the cutting tool 4, a vibration sensor 1 is attached to the end of the cutting tool 4, and a frequency analyzer 3 measures the frequency (F _c ) producing the maximum vibration output via an amplifier 2. . Experiment cutting speed
Work material 5 (carbon steel JIS S25C) was cut under various conditions of 120 m/min, depth of cut 3 mm, and feed rate 0.05 to 0.5 mm/rotation, and the state of breakage of chips 6 was examined.

As an evaluation method for the state of separation, if the chip is separated within one curl, it will be given a score of 10, if it is separated within two curls, it will be given a score of 9, and so on. , 8, 7, 6, 5, respectively when divided within 7, 8, and 9 curls.
4, 3, 2 points, 1 point if the chip is less than 10 curls, 0 point if the chip is 11 curls or more, and the feed rate is 0.05, 0.08,
0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40,
Eleven conditions were set: 0.45, 0.5 mm/rotation.

The test was repeated 10 times under the same conditions, and the average score was taken as the chip control evaluation score.

The vertical axis is the chip control performance (maximum 10 points, minimum 0 points) obtained in the test using the device shown in Figure 6, and the horizontal axis is the digital count value obtained by digitally counting the amount proportional to the total output of the vibration signal at that time. Figure 2 shows the results of examining the correlation using the axis. As shown in the figure, we were unable to find any correlation between the two.

However, as shown in FIG. 1, in all experiments within the above frequency range, it was found that the maximum output (peak value) existed between 0.1 and 10 KHz. Below 0.1KHz, vibrations other than cutting, such as low-frequency vibrations of machine tool motors and vibrations thought to be generated from vibrating parts of machines, were excluded because they sometimes occur. In addition, the output above 10KHz was small and had little relation to the measured data, so it was excluded.

When we focused on the frequency (referred to as F _c ) that indicates the peak value obtained, we found that while F _c had good chip control in the initial stage of cutting, this F _c fluctuated as the cutting time progressed. I understood. Therefore, when we investigated the ratio p [F _c / (F _c ) ₀ ] of F _c to F _c at the initial stage of cutting (this is defined as (F _c ) ₀ ) and the quality of chip control, we found that the results are as shown in Figure 3. p
It was found that [F _c /(F _c ) ₀ ] worsens as it moves away from 1, and if it becomes less than 1/2 or more than 2, it is unfavorable from the viewpoint of work safety, tool damage, and quality of the workpiece. There was found.

This invention embodies the above idea, and an embodiment thereof is shown in FIG.

In FIG. 4, a detector 1 is attached to a cutting tool or a machine tool, and is adapted to detect vibration signals using an accelerometer, an AE signal measuring element, or the like. The detected signal is input to the next amplifier 2 and amplified.

The amplified signal is processed in frequency analyzer 3.
The frequency of the maximum output value between 0.1 and 10KHZ is analyzed and the frequency is input to the next comparator 4.

The comparator 4 compares the signal with a preset reference value (the F _c value at the initial stage of cutting), and activates the alarm 5 when the ratio of the signal to the reference value becomes 1/2 or less or 2 or more. Then, the operation is stopped by issuing an alarm, stopping the machine tool, or returning the cutting tool to its original setting position.

FIG. 5 shows the time t in the above embodiment on the horizontal axis and the ratio p between the frequency of the maximum output value between 0.1 and 10 KHZ and the reference value on the vertical axis. ₁ , an abnormality occurs in chip control, p suddenly increases, and an alarm is issued when the safety range Δp is exceeded.

In this invention, among the signals generated from the tool or machine tool during cutting, the frequency indicating the maximum output value between 0.1 and 10KHZ changes with the passage of cutting time, and the ratio with the initial value is We discovered that there is a high correlation with the properties of chips, and based on this we were able to automatically detect the chip disposability.

Therefore, according to the device of the present invention, the chip disposability of a cutting tool can be detected with high precision and with a simple device.

[Brief explanation of the drawing]

Figure 1 is a frequency distribution diagram of vibration output generated during cutting, Figure 2 is a correlation diagram between total vibration output and chip control, and Figure 3 is 0.1 to 10KHZ.
Correlation diagram between the ratio p to the reference value (initial value) of the frequency indicating the maximum output value between and the chip control performance,
Fig. 4 is a block diagram showing an embodiment of the present invention, Fig. 5 is a graph of the relationship between the output ratio p and time, and Fig. 6 is a device used to obtain the correlation shown in Figs. 2 and 3. FIG. 1 is a detector, 2 is an amplifier, 3 is a frequency analyzer,
4 is a comparator, 5 is an alarm.

Claims (1)

[Claims] 1. A detector that is attached to a tool or machine tool and detects vibration signals generated during cutting, and a frequency that exhibits the maximum output for signals in the range of 0.1 to 10 KHz among the detection signals of the detector. A frequency analyzer that detects (F _c ), and a frequency [(F _c ) ₀ ] that indicates good chip control immediately after the start of cutting is used as a reference value, and this reference value,
and a comparator that compares the frequency (F _c ) indicating the maximum output that varies with the progress of cutting, and the comparator detects that the ratio is outside the range of 1/2 to 2. A chip disposability detection device characterized in that the chip disposability is determined to be poor when the chip disposability is determined to be poor.