JPS6128467B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device that automatically detects damage such as wear and chipping of a rotary cutting tool.

In recent years, rotary cutting tools have begun to use better ceramics and hard alloys in order to become more efficient and unmanned, and the number of cutting edges they possess is also increasing. On the other hand, the state of wear and chipping during use varies, making unmanned operation extremely difficult, and if chipping leads to major damage, the processed product may be defective or the holding tool itself may be damaged.

This invention aims to grasp the damage situation during the use of rotary cutting tools with cutting blades made of hard alloys whose main components are ceramics, carbides, nitrides, carbonitrides, etc., and prevent accidents in advance if possible. The present invention aims to provide a damage detection device with improved performance.

It is known that when damage occurs to a rotary cutting tool in use, the output level of an acoustic emission signal (hereinafter simply referred to as AE signal) generated from the cutting edge increases. Therefore, the first problem facing the damage detection device is how to accurately and easily detect a component with a high output level when it appears in the AE signal.

So, let's take a face milling cutter as an example and change the AE signal from 0 to
When we investigated the AE output during use limited to the frequency of 2000KHz, we found the distribution shown in Figure 1. Figure 2 shows the results of examining the sensitivity to damage by measuring the rate of increase in output after damage relative to the output before damage. Damage can be detected with good sensitivity by extracting frequency components below 100 KHz, but preferably 100 to 1000 KHz.
In the Hz range, the increase rate is 3 or more, allowing for highly sensitive and accurate detection.

On the other hand, in the present invention, the second problem is how to receive an AE signal from a rotating body called a rotary cutting tool with less noise.

Since the AE signal consists of frequency components in a very wide range, it is easy for noise to be mixed in with it, and it is especially difficult to accurately detect damage to the cutting edge when the signal is extracted from a rotating body through a commercially available slip spring. is difficult.

Therefore, the present invention has a configuration in which the AE signal is extracted without contact using an FM transmitter, so that the AE signal that detects damage to the cutting edge can be extracted externally with high accuracy, and this is set as a value preset in the non-rotating part. When a signal exceeds a set value, a warning is issued to prevent accidents involving rotary cutting tools and processed products.

Examples will be described below.

In Fig. 3, 1 is a rotary cutting tool, 2 is a cemented carbide cutting blade, and 3 rotates together with the rotary cutting tool 1.
AE signal detector, 4 a wireless transmitter, 5 a wireless receiver that does not contact or rotate the cutting tool 1;
6 is an amplifier, 7 is a frequency discriminator, 8 is a comparator, 9
is an alarm.

The above-mentioned detector 3 is installed inside the rotary cutting tool body, and is configured to detect an AE signal using an AE signal measuring element.

The detected signal is transmitted through a radio transmitter 4 which, like the detector 3, is fixed within the rotary cutting tool body. The transmitted signal was received by a receiver 5 provided in a non-rotating part that is not in contact with the rotary cutting tool 1.

The received AE signal is input to the amplifier 6 and amplified, and the output of the AE signal is below 100KHz and 1000KHz.
The above frequency components are removed by the next frequency discriminator 7, and among the outputs of only the remaining frequency components, the outputs that are equal to or higher than a preset reference value are input to the next comparator 8.

The comparator 8 compares the AE signal with a preset reference value, and when the increase rate P of the AE signal exceeds the reference value _P1 , the alarm 9 is activated to issue an alarm or take an action related to cutting. Stop the work by stopping the work.

FIG. 4 shows time t on the horizontal axis and increase rate P of the frequency component of the AE signal from 100 to 1000 KHz on the vertical axis in the above embodiment, and shows the time t ₁
This indicates that damage occurred to the cutting edge. Due to the occurrence of damage, the output P increases rapidly, and when it exceeds the reference value _P1 , an alarm is issued.

This invention deals with the problem of
We discovered that there is a correlation between the frequency components of 100 to 1000 KHz in the AE signal and damage to the cutting edge, and in order to more sensitively extract this AE signal from rotating objects to external non-rotating parts, we transmitted and received it wirelessly. By incorporating a device with the following functions, it is possible to automatically detect damage to a rotary cutting tool.

Therefore, by using the configuration of the present invention, it is possible to accurately and easily detect damage to a rotary cutting tool.

[Brief explanation of the drawing]

Figure 1 is a distribution diagram of the AE signal output generated during cutting with respect to frequency, Figure 2 is a diagram of the ratio (increase rate) of AE signals before and after damage occurs with respect to frequency, and Figure 3 is an example of this example. Figure 4 showing
The figure is a graph showing the relationship between the rate of increase in the frequency range of 100 to 1000 KHz and time. DESCRIPTION OF SYMBOLS 1...Rotary cutting tool, 2...Cemented carbide cutting blade, 3...Detector, 4...Radio transmitter, 5...Radio receiver, 6...Amplifier, 7...Frequency discriminator, 8...Comparator, 9...Alarm device .

Claims (1)

[Claims] 1. A detector for detecting an acoustic emission signal and a transmitter for wirelessly transmitting the signal from the detector are installed in the rotating part of a rotary cutting tool whose cutting edge is made of ceramic or hard alloy, and the rotary cutting tool is a receiver that receives the signal from the transmitter in a non-rotating part or outside; an amplifier that amplifies the signal received by the receiver; a discriminator that discriminates frequency components in the range of , and a rate of increase in the output of the frequency component connected to the discriminator and discriminated by the discriminator is compared with a preset reference value, and the rate of increase exceeds the reference value. A rotary cutting tool equipped with a tool damage detector, characterized in that it is provided with a comparator configured to issue a signal when the tool is damaged.