JP2001030142A - Method and device for detecting machining state of machine tool and cutting tool used in this device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for detecting the machining state of a machine tool to detect a micro-machining state change at a microportion with high response and high resolving power without being influenced by disturbance and to provide a cutting tool used in this device. SOLUTION: In a method for detecting a machining state, temperature in the vicinity of the cutting edge 3 of a cutting tool 1 under a cutting process is detected, and based on the detecting temperature and a temperature change pattern, the machining state of a machine tool is detected. In a machining state detecting device, temperature in the vicinity of the cutting edge 3 of the cutting tool 1 under a cutting process is detected by a temperature detecting means, and based on an output therefrom, the machining state of the machine tool is detected by a machining state detecting means. In the cutting tool 1, a temperature sensor 5 is situated in the vicinity of the cutting edge 3 of a blade part 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for detecting a machining state of a machine tool such as a cutting machine, and a cutting tool used therefor.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for higher precision and higher efficiency of production systems.
The number of skilled technicians and skilled technicians who actually support highly automated production systems behind the scenes is declining both quantitatively and qualitatively. For this reason, there is a demand in the industry to rationally implement an intelligent production system that exceeds the functions of conventional production systems.

In order to realize such a next-generation production environment, it is possible to accurately and in-process recognize the machining state including the operating state of a machine tool such as a cutting machine or a machining apparatus, which is a core machining function in a production system. Establishing high-performance monitoring technology has become an important issue. In particular,
It is essential to establish high-performance in-process monitoring technology in order to achieve highly efficient ultra-precision machining while eliminating the effects of various disturbances.

[0004] From such a viewpoint, conventionally, an AE (acoustic emission) sensor or a cutting dynamometer having a crystal piezoelectric element is incorporated in a tool mount to generate a machining state, for example, occurrence of chipping, wear, and vibration of the tool. Research to detect such things has been performed sporadically at the laboratory level.

[0005]

However, in the case of using an AE sensor, it is difficult to detect a weak acoustic signal caused by a minute breakage of a tool material caused by the occurrence or progress of tool loss or tool wear. In addition, when using a quartz crystal element, it is difficult to stably detect a small change in the cutting force during processing, and,
In any case, since a weak signal targeted for various disturbances is buried, it is only possible to monitor large destruction or wear. In any case, in ultra-precision machining for small cutting areas, the signal level is weak, and the accuracy of recognition is low because of the influence of disturbance. Difficult to apply. For these reasons, in any case, the research is limited to laboratory-level basic research and is not actually applied to the processing site.

Accordingly, the present inventors have conducted intensive studies and found that the temperature near the cutting edge of a cutting tool during cutting is affected by machining conditions such as a cutting depth and a feed length, chatter vibration,
It has been found that the change pattern is different depending on a minute change of a processing state such as entanglement of chips, abrasion and the like. Therefore, if temperature patterns in various machining states are measured in advance, it is possible to detect minute changes in machining state with high response and high resolution based on a comparison between those temperature patterns and the detected temperature during actual cutting. I understood.

The present invention has been made in view of such a point, and an object of the present invention is to detect a minute change in a machining state in a minute portion with high response and high resolution without being affected by disturbance. An object of the present invention is to provide a method and an apparatus for detecting a machining state of a machine tool and a cutting tool used for the method and apparatus.

[0008]

According to a first aspect of the present invention, there is provided a method for detecting a machining state of a machine tool, comprising detecting a temperature near a cutting edge of a cutting tool during cutting, and detecting the detected temperature and the temperature. The processing state of the machine tool is detected based on the temperature change pattern.

Further, the invention of a machine tool machining state detecting apparatus according to a second aspect of the present invention, which achieves the above object, comprises a temperature detecting means for detecting a temperature near a cutting edge of a cutting tool during cutting, and the temperature detecting means. And a machining state detecting means for detecting the machining state of the machine tool based on the output of the above.

According to a third aspect of the present invention, in the machining state detecting device for a machine tool according to the second aspect, the temperature detecting means has a temperature sensor provided on a blade portion of the cutting tool. Things.

According to a fourth aspect of the present invention, in the apparatus for detecting a machining state of a machine tool according to the second aspect, the temperature detecting means includes a non-contact type temperature sensor, and the non-contact type temperature sensor detects the temperature of the cutting tool. It is characterized in that it is configured to detect the temperature of the blade portion.

According to a fifth aspect of the present invention, there is provided a cutting tool for use in a method for detecting a machining state of a machine tool according to the first aspect, wherein the cutting tool is provided near a cutting edge of a cutting portion. Characterized by comprising a temperature sensor.

According to a sixth aspect of the present invention, in the cutting tool according to the fifth aspect, the temperature sensor is formed of a thin-film platinum resistance temperature detector formed on a rake face by a semiconductor manufacturing process. It is assumed that.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of an example of a cutting tool according to the present invention. FIG. 1 (a) is a plan view, and FIG. 1 (b) is an enlarged view of a temperature sensor. This cutting tool 1 is a single crystal diamond tool used for ultra-precision machining, and a rake face 4 near a cutting edge (edge) 3 of a cutting portion 2.
The temperature sensor 5 is provided thereon. The temperature sensor 5 is a microsensor having a small heat capacity, and is formed in a thin film shape by a semiconductor manufacturing process and has a rectangular wave-shaped temperature measuring portion 6 made of a platinum temperature measuring resistor, and both ends of the rectangular wave-shaped platinum temperature measuring resistor. And electrode portions 7a and 7b formed of platinum resistance temperature detectors, respectively. In addition, FIG.
In (b), the tool total length L, the cutting edge corner R, the dimension a from the cutting edge 3 to the tip of the temperature measuring unit 6, the length b and the width c of the temperature measuring unit 6, and the width of the platinum resistance temperature detector in the temperature measuring unit 6. The distance d, the distance e, the length f and the width g of the electrode portions 7a and 7b are, for example, L = 10.50 mm, R = 0.2 mm, a = 1.0.
0 mm, b = 128 μm, c = 128 μm, d = 8 μ
m, e = 16 μm, f = 436 μm, and g = 444 μm.

FIGS. 2A to 2H are sequential process diagrams illustrating a method of manufacturing the temperature sensor 5 shown in FIG. Here, since the sensor pattern is formed by electron beam lithography, considering that diamond is an insulating material, antistatic as shown in FIG. 2B is formed on the rake face 4 shown in FIG. Aluminum thin film 11 is formed by sputtering. Next, after forming a resist film 12 and drawing a sensor pattern with an electron beam drawing apparatus, the resist pattern is etched with a strong alkaline developer to form a pattern as drawn as shown in FIG. The resist film 12 is made of, for example, NPR (New Po
(sitive Resist).

After that, as shown in FIG. 2D, a platinum thin film 13 is formed by sputtering, and then a platinum film other than the platinum thin film of the sensor pattern portion is formed by a lift-off method using, for example, methyl ethyl ketone as shown in FIG. 2E. The thin film is removed simultaneously with the resist film 12. Next, the aluminum thin film 11 other than the sensor pattern portion is completely removed using a strong alkaline solution, and a platinum thin film 13 as shown in FIG.
To obtain a sensor pattern.

Next, as shown in FIG. 2 (g), after conducting wires 15a, 15b are respectively connected to the electrode portions 7a, 7b of the sensor pattern by using silver paste 14, the sensor pattern as shown in FIG. A cutting tool 1 having a temperature sensor 5 is completed by forming a protective layer 16 made of, for example, an epoxy resin on the pattern portion. FIG. 3 is an optical microscope photograph of the temperature sensor 5 thus formed.

As described above, since the temperature sensor 5 shown in FIG. 1 can be formed on the blade portion 2 of the cutting tool 1 by a semiconductor manufacturing process, it can be easily mass-produced.

FIG. 4 is a schematic diagram showing the configuration of an example of the processing state detecting device for a machine tool according to the present invention. This processing state detection device detects the processing state of a machine tool 21 that performs ultra-precision diamond processing using the cutting tool 1 shown in FIG. 1. The machine tool 21 controls a machine tool control device 23 by a computer 22. Is controlled via the The temperature sensor 5 provided on the cutting tool 1 is connected to a temperature measurement circuit 24, and supplies the output of the temperature measurement circuit 24 to the computer 22.

A memory 25 is connected to the computer 22, and a signal pattern obtained from the temperature measuring circuit 24 is previously stored in the memory 25 in accordance with various processing states. In this way, the computer 22 searches the memory 25 for a signal pattern corresponding to the output pattern obtained from the temperature measuring circuit 24 during the actual processing, determines the processing state, and displays the determination result on the display device 26. I do.

FIG. 5 shows an example of the configuration of the temperature measuring circuit 24 shown in FIG. This temperature measurement circuit 24
The temperature is measured by a bridge circuit. The temperature sensor 5 and the semi-fixed resistor 31 are connected in series to one side of the bridge circuit, and the fixed resistors 32 are connected to the other three sides.
A DC power supply 33 is connected to the bridge circuit, the output of the DC power supply 33 is amplified by an amplifier 34, the temperature is detected as a voltage, and the detected voltage is supplied to the computer 22.

Here, the DC power supply 33 is, for example, 2.5
V, the fixed resistor 32 is, for example, 10 kΩ, and the semi-fixed resistor 3 is
1 is, for example, a temperature of 20 ° C. and the combined resistance with the temperature sensor 5 is 1
Adjust so as to be 0 kΩ. In this way, a temperature change based on a minute change in the machining state causes a change in the electrical balance caused by a change in the resistance of the temperature sensor 5 to detect the temperature as a change in the output voltage with respect to the input voltage.

FIG. 6 shows the output characteristics of the temperature measuring circuit 24 shown in FIG. As is clear from FIG.
According to the temperature measuring circuit 24 shown in FIG. 5, a linear output signal proportional to the temperature can be obtained.

Next, a specific example of an output pattern obtained from the temperature measuring circuit 24 when ultra-precision diamond processing is actually performed using the cutting tool 1 in the processing state detecting device shown in FIG. .

FIG. 7 shows an output pattern when the cutting amount of the cutting tool is changed for the same work (not shown). As can be seen from FIG. 7, the rate of change of the output signal increases as the amount of cut increases, and it is clear that a change in the amount of cut of several μm can be clearly distinguished.

When the surface of the disk 41 as shown in FIG. 8A is cut as a work, an output signal as shown in FIG. 8B is obtained. Here, the disk 41 shown in FIG. 8A has a width of 0.32 mm and 0.22 m on the surface.
grooves 42 each having a depth of 10 μm and a depth of 0.12 mm.
a, 42b and 43c. FIG. 8 (b)
Shows an output signal when the disk surface is cut from the inner peripheral side toward the outer peripheral side with a cutting depth of 5 μm.

As is apparent from FIG. 8B, when the cutting amount suddenly changes, the output signal decreases instantaneously in accordance with the sudden change in the cutting amount. It can be seen that it is a response, and is hardly affected by a sudden change in the cut amount.

FIG. 9 shows an output signal (solid line A) when chips to be discharged are entangled with the tip of the cutting tool being processed, and an output signal when chips are discharged normally. (Broken line B). As is apparent from FIG. 9, when the chips are entangled, the heat of the chips is detected by the temperature sensor. You can see that 7 and 8
9B and FIG. 9, ΔT [° C.] represents a change from a reference temperature (for example, 20 ° C.).

In the above description, the output pattern in the machining state of the cutting depth and the entanglement of the chips has been exemplified. However, in the other machining states, for example, the minute pattern at the cutting point typified by wear of the cutting tool and chatter vibration. A characteristic output pattern corresponding to each processing state is also shown by a change in thermal characteristics.

As is clear from the above, since the output of the temperature measuring circuit 24 indicates a characteristic pattern according to various processing states, those signal patterns are stored in the memory 25 in advance, and the actual processing is performed. A signal pattern corresponding to the output pattern obtained from the temperature measurement circuit 24 is stored in the memory 2.
By searching from No. 5, various machining states can be qualitatively and quantitatively determined without being largely affected by a sudden change in the cutting amount. Therefore, for example, during cutting of the aspherical mirror, it is possible to quickly detect the entanglement of chips at the tip of the cutting tool, and it is possible to minimize damage to the machined surface.

According to the processing state detecting device shown in FIG.
The temperature sensor 5 provided on the cutting tool 1 has a simple and micro structure, has a small heat capacity, and can detect the temperature near the cutting edge 3 with high response and high resolution. It is possible to detect not only the state of a single phenomenon but also various states of multiple phenomena simultaneously with high accuracy. Also, unlike a large-scale sensor such as a cutting dynamometer, which conventionally had to be installed at a location distant from the processing point, the microstructure of the blade portion 2 of the cutting tool 1 near the processing point closest to the measurement target is provided. Since the temperature sensor 5 is provided, the processing site is not disturbed at all.

FIG. 10 is a schematic diagram showing the configuration of another example of a machine state detection device for a machine tool according to the present invention. This processing state detection device uses a non-contact type thermopile 51 as a temperature sensor, connects the thermopile 51 to the temperature measurement circuit 24, and detects the temperature of the blade portion of the cutting tool 52 in a non-contact manner. The other configuration is the same as that of FIG.

As described above, even when the non-contact type thermopile 51 is used as the temperature sensor, as in the case of using the cutting tool having the temperature sensor shown in FIG. Since the output of the characteristic signal pattern corresponding to the above can be obtained, those signal patterns are stored in the memory 25 in advance, and the signal pattern corresponding to the output pattern obtained from the temperature measurement circuit 24 during the actual processing is obtained. By searching from the memory 25, various processing states can be qualitatively and quantitatively determined.

It should be noted that the present invention is not limited to the above-described example, and various modifications or changes can be made. For example, in FIG. 1, the temperature sensor 5 is provided on a single crystal diamond tool as the cutting tool 1, but the temperature sensor 5 may be provided on other cutting tools such as a polycrystalline diamond tool, a CBN tool, and a cermet tool in the same manner. it can. Further, the temperature sensor 5 is not limited to a sensor using a platinum resistance temperature detector,
A thermocouple may be provided near the cutting edge of the blade of the cutting tool to detect the temperature of the blade. Further, the temperature sensor for detecting the temperature of the blade portion in a non-contact manner is not limited to the above-mentioned thermopile, and a known infrared sensor may be used. Further, in the machining state detecting device shown in FIGS.
A temperature measuring circuit 24 is provided on the side, a transmitting circuit for wirelessly transmitting the output is provided, and a receiving circuit for receiving temperature data wirelessly transmitted from the cutting tool itself or the transmitting circuit on the machine tool 21 is provided on the computer 22 side. In this case, the temperature detected by the cutting tool blade may be wirelessly transmitted to the computer 22. This eliminates the need for extra wiring between the machine tool 21 and the computer 22, and facilitates the use of the cutting tool with various machine tools, particularly when the cutting tool itself is provided with a transmission circuit. It can be used.

[0035]

As described above, according to the method for detecting a machining state of a machine tool according to the present invention, the temperature near the cutting edge of a cutting tool during cutting is detected, and based on the detected temperature and the temperature change pattern. Since the machining state of the machine tool is detected, a minute change in the machining state at a minute part can be detected with high response and high resolution without being affected by disturbance.

Further, according to the machine tool processing state detecting apparatus of the present invention, the temperature detecting means for detecting the temperature near the cutting edge of the cutting tool during cutting, and the machine tool based on the output of the temperature detecting means. With a simple configuration having a machining state detecting means for detecting the machining state, a minute change in the machining state in a minute portion can be detected with high response and high resolution without being affected by disturbance.

Further, according to the cutting tool of the present invention,
Since the temperature sensor is provided in the vicinity of the cutting edge of the blade portion, it can be easily mass-produced without disturbing the processing site, especially when the temperature sensor is formed by a semiconductor manufacturing process.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of the configuration of a cutting tool according to the present invention and an enlarged view of a temperature sensor.

FIG. 2 is a sequential process chart illustrating a method for manufacturing the temperature sensor shown in FIG.

FIG. 3 is an optical microscope photograph of the temperature sensor shown in FIG.

FIG. 4 is a schematic diagram showing a configuration of an example of a machine tool processing state detection device according to the present invention.

FIG. 5 is a diagram illustrating a configuration of an example of a temperature measurement circuit illustrated in FIG. 4;

6 is an output characteristic diagram of the temperature measurement circuit shown in FIG.

FIG. 7 is a diagram illustrating an output pattern of a temperature measurement circuit when a cutting amount of a cutting tool is changed.

FIG. 8 is a sectional view of a work having a groove and a diagram showing an output pattern of a temperature measuring circuit obtained by cutting the work.

FIG. 9 is a diagram showing a comparison of output patterns obtained from the temperature measurement circuit when chips are entangled with the tip of the cutting tool and when chips are not entangled.

FIG. 10 is a schematic diagram showing a configuration of another example of the machine tool processing state detection device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cutting tool 2 Blade part 3 Cutting edge (cutting edge) 4 Rake surface 5 Temperature sensor 6 Temperature measuring part 7a, 7b Electrode part 11 Aluminum thin film 12 Resist film 13 Platinum thin film 14 Silver paste 15a, 15b Conducting wire 16 Protective layer 21 Machine tool 22 Computer 23 Machine tool controller 24 Temperature measuring circuit 25 Memory 26 Display device 31 Semi-fixed resistor 32 Fixed resistor 33 DC power supply 34 Amplifier 41 Disk 42a, 42b, 43c Groove 51 Thermopile 52 Cutting tool

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Claims (6)

[Claims] 1. A method for detecting a machining state of a machine tool, comprising detecting a temperature near a cutting edge of a cutting tool during cutting, and detecting a machining state of the machine tool based on the detected temperature and a temperature change pattern. Method. 2. A temperature detecting means for detecting a temperature near a cutting edge of a cutting tool during cutting, and a processing state detecting means for detecting a processing state of a machine tool based on an output of the temperature detecting means. A machine state detection device for a machine tool. 3. The apparatus according to claim 2, wherein said temperature detecting means includes a temperature sensor provided on a blade portion of said cutting tool. 4. The apparatus according to claim 2, wherein said temperature detecting means has a non-contact type temperature sensor, and the non-contact type temperature sensor detects a temperature of a blade portion of said cutting tool.
3. The processing state detection device for a machine tool according to claim 1. 5. A cutting tool for use in the method for detecting a machining state of a machine tool according to claim 1, further comprising a temperature sensor provided near a cutting edge of the blade portion. 6. The cutting tool according to claim 5, wherein the temperature sensor is made of a thin-film platinum resistance temperature detector formed on a rake face by a semiconductor manufacturing process.