JPS6090659A - Damage detecting apparatus for machining tool - Google Patents

Abstract

PURPOSE:To permit the detection for the damage of a various sorts of tools under a variety of conditions by measuring the load electric-current value during machining work and detecting the existence and the state of the damage of the tool from the variation state of said electric current, in a damage detecting apparatus for the machining tool. CONSTITUTION:When a machined material 5 is mounted onto a lathe and machined by a tool 6, a signal detection part 7 converts the motor electric current in the feeding direction into a processable signal in an electric circuit, and said signal is detected. The signal converted and detected by the signal detection part 7 is processed by a signal processing part 8 to facilitate the treatment in the subsequent stages. For example, removal of noise through filtering, amplification and digital conversion of signal, etc. are performed. A condition setting part 9 sets a judging level. A behavior detecting part 10 observes a damage judging level for the tool, in other words, observes if the detection signal exceeds the set value in the condition setting part 9 or not, and outputs the result into a damage judging part 11. Said damage judging part 11 receives the result of observation in the behavior detecting part 10, and judges the existence of generation of damage, and transmits an instruction into an output part 12.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for detecting tool abnormalities (repairs) during cutting.

There is still interest in the automation of machine tools, as mentioned above, and many automatic machine tools, including NC machines, have been put into practical use. In order to ensure the stable body movement of such automatic machine tools, it is necessary to put into practical use a device that detects abnormal noises from the tool and generates four alarms when the machine is stopped. Many proposals have been made regarding detection of abnormalities in cutting tools. Particularly recently, with the development of various error detectors and signal processing technology, during cutting (
There is growing interest in in-process detection methods and devices.

By the way, conventional tool abnormality detection uses various signals (fullness is cutting resistance) caused by damage to the tool.

The approach was to indirectly detect tool loss by measuring changes in cutting temperature, cutting sound, vibration, Mome current, acoustic emission). However, these indirect detection methods have problems in terms of accuracy and reliability of abnormality determination because the target detection signal fluctuates due to changes in cutting conditions 1 and dynamic characteristics of the machine. In other words, the tangent method is a method in which a reference direct (threshold) is set and the detected signal level is compared with the threshold (hereinafter tentatively referred to as the threshold direct method). ), the threshold value changes depending on cutting conditions and processing methods, and setting the threshold value itself becomes a national problem. Furthermore, it seems to be a shame that there are almost no devices that can be used in the field to deal with forms of damage such as chin-pink, missing, damaged 2M bills, etc.

The present invention solves the runner-up fc of the threshold direct method in the in-process Ii5 direct tool damage detection method, and enables tool damage detection under multiple machine shields and multiple conditions. Providing detection equipment? l-It is aimed at. The present invention, which achieves this object, has a method in which the load applied to the drive system (for example, feed direction motor current) exhibits characteristic behavior during cutting 6u processing when tool damage occurs and during the cutting Sa process before that. Focusing on this, we measured the load asahi flow during cutting, and
The gist is to detect the presence or absence of tool damage and its form from its fluctuating state.

Hereinafter, the tool damage detection at of the present invention will be explained in detail.

First, the fact that the feed direction motor current exhibits a 4if-deceptive behavior during the cutting process when damage occurs and before that will be explained using an IfI diagram. FIG. 1 shows an example of the behavior of the feed direction motor relaxation value under continuous cutting with one foot load, where the horizontal axis shows the time course and the vertical axis shows the signal level.

As is clear from the figure, normal cutting q from cutting starting point a
The signal level at t+ remains constant without any fluctuation. However, from the point before the damage occurs, a linear slope of the signal level, that is, a first-order integral 1, begins, then a curved part, that is, a second-order integral 2, occurs, and a sudden level change 3 occurs at C when damage occurs. do.

In addition, during the cutting process, there may be a case where the signal level exceeds a certain tolerance level (threshold b value exceeds 4, which is equal to or higher than threshold value 9).

Note that d is the cutting length T point.

For almost all damage types, the above behavior 1.2, 3.4 occurs at the time of damage occurrence and during the cutting pJu process before that.
occur singly or in combination. Therefore, by monitoring the above 1, 2° and 3.40 items regarding the fluctuation state of the feed direction motor current during the cutting PA process,
It is possible to detect the occurrence of tool injuries. Moreover, the first order image component 1 and the second order differential 2 often occur before the occurrence of damage, and monitoring of these items can also be applied to predicting the occurrence of damage.

The above results were obtained through detailed cutting tests under various woodcutter conditions.

Next, the tool of the present invention! A specific example of the j4 flaw detection device will be described.

FIG. 2(a), Φ) is a conceptual diagram of a cutting machine and a block diagram showing the basic configuration of a tool damage detection device. In the figure, 5 is a 1gt+ material mounted on a lathe, and 6 is a tool.

The direction indicated by the arrow in the figure is the feed direction, and the motor serving as the drive source in the direction is determined by the feed direction motor current. 7 is a signal detection section, which detects the feed direction motor current? I- Converts into a signal (for example, voltage signal) that can be processed by an electric circuit and detects it. For example, it can be constructed by a well-known flow divider. Reference numeral 8 denotes a signal processing unit which processes the signal converted and detected by the signal detection unit 7 so that it can be easily handled at a subsequent stage. For example, noise removal through filtering.

Signal amplification and digitization 4! I do. (Incidentally, if the feed direction motor is an AC motor, the motor accent is 60
Hz mer b is 501 (the rimple of Z is overlapping).

In order to remove this, 59.58Z ~ 60.5Hz
It is effective to perform fluorescent range exclusion filtering of about 49.5 H2 to 50.5 H7. )
9 is required in the condition setting section, and the above-mentioned first-order thoroughness l and second-order thoroughness 2
．． This is to set the determination level for detecting rapid level change 3 and exceeding threshold value 4. For example, as the signal klooX when a certain time has elapsed after the start of cutting 1'JJ, the increase (%) from then on (in the case of 1 and 2, the method is to set the increase per constant time.lO is the behavior The detection unit monitors whether or not the detection signal exceeds the set value in the condition setting unit 9 for items 1, 2, and 3.4, and outputs the result of item 7 to the damage determination unit 11.Damage Judgment part 11 ¥1,
In response to the monitoring results from the behavior detection unit 1O, it is determined whether or not damage has occurred (tl-), and a command is issued to the output unit 12. (For example, regarding monitoring target items 1.2 and 3.4, the monitoring results are 1°4.
If the occurrence occurs in the order of 2.3, it is determined as I damage occurrence 1 and a command is sent to the machine stop signal full output section 12. Alternatively, if the state of 4 continues for a certain period of time or more, all operations such as commanding an alarm signal as 1M&occurrence 1 are performed. ] As explained above, Yl according to the present invention extracts and monitors the characteristic behavior of the signal during the cutting process, and is evaluated based on the change m (X 匝) based on the signal level at the start of cutting. By using this method in combination, it can be applied to detect various forms of damage under various cutting conditions. In addition, since even the −th differential and second-order complete tweets are monitored,
It is also possible to output warnings, warnings, etc. immediately before damage occurs.

In addition, for cutting conditions such as machining of the lt part or the tapered part, where the first order integral l and the second order differential 2 occur even during normal machining, only the sudden level change 3 and the threshold excess 4 will be damaged. This is the target item for judgment. Alternatively, during intermittent cutting, it is also possible to use a method such as creating a signal envelope M-line using the signal processing section 8, without changing the gist of "unexploded".

In addition, in the explanation of FIG. 2, each block was explained as a separate unit, but it is also possible to process part or all of these with a microcomputer, minicomputer, etc., without changing the above configuration. Variations within the range are possible.

In addition, in this specification, the feed motor current was explained as an example of the load applied to the drive system, but the characteristics of the target machine tool
It is of course possible to use the motor current in the cutting direction (R component force direction) or the rotation direction (main force component direction) depending on the conditions.

As specifically explained above in conjunction with the embodiments, according to the present invention, the selection of cutting tools can be detected with high precision.

[Brief explanation of the drawing]

Fig. 1 is a characteristic diagram showing the characteristics of the feeding direction motor commutation direct, Fig. 2 (al is a conceptual diagram showing the cutting machine in conceptual white, and Fig. 2 (b) is a block diagram showing the embodiment of the present invention. In the drawing, l is the first derivative, 2 is the second derivative, 3 is the rapid level change, 4 is the threshold rK exceeded A, 6 is the tool, 7 is the signal detection part, 8 is the signal processing part, 9 is the signal processing part. 1 is a condition setting section, io is a behavior detection section, 11 is a damage determination section, and 12 is an output section.

Claims (1)

[Claims] load detection means for detecting the load applied to the drive system of a machine tool and sending it out as a load signal;
a signal processing means for sending out a time-series signal capable of
Behavior detection biomembrane that monitors and detects linear increasing trends, curvilinear increasing trends, sudden level changes, and exceedance of the time-series signals, and judgment levels for the monitoring and detection items. a condition setting means for setting, a damage determination means for determining the presence or absence of tool perturbation based on the monitoring and detection results in the friction detection contest, and a damage determination means for determining the presence or absence of tool perturbation based on the determination result by the damage determination means. A damage detection device for a cutting tool characterized by being formed from an output means for outputting information on each woodcutter.