JP2002331442A - Eccentricity detecting device of tool holder of machine tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for detecting abnormality of a clamp by automatically measuring an eccentric quantity at clamping time of a tool holder replaceably installed on a main spindle of a machine tool. SOLUTION: A spindle stock 100 of the machine tool rotatably supports the main spindle 110. The tool holder 120 is installed on the main spindle 110 by an automatic tool replacing device. The tool holder 120 has a flange 122. An eccentricity detecting device 200 of the tool holder is arranged in a position opposed to this flange 122. The eccentricity detecting device 200 has an eddy current type sensor head 210, and measures a change in a clearance distance G1 with the flange 122 of the tool holder in a noncontact state. When the change in the clearance distance G1 is large, since the tool holder 120 is eccentrically clamped, the clamp is determined as abnormal, and processing is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting that foreign matter has adhered between a spindle and a tool holder when the tool holder is mounted on a spindle of a machine tool.

[0002]

2. Description of the Related Art For example, in a machine tool provided with an automatic tool changer such as a machining center, a tool holder for a spindle is automatically changed by a robot arm. Chips and the like tend to adhere to the spindle during cutting. In automatic tool change, the spindle is moved to a tool change position, and a new tool holder is exchanged between tool holders stored in the tool magazine.

[0003]

When the tool holder is inserted into the shank hole of the main shaft, foreign matter such as chips may be caught between the tool holder and the main shaft. When foreign matter such as chips is present, the axis of rotation of the spindle does not coincide with the axis of the tool holder, and the tool holder is mounted on the spindle in an eccentric state. When the main spindle is rotated in this state, the entire main spindle vibrates, and the cutting edge is displaced from a predetermined position. .

For example, JP-A-3-35952 discloses that
Disclosed is a technique for detecting vibration caused by rotation of a spindle with a vibrometer to detect eccentricity of the spindle. However, in the technique described in the above-mentioned publication, since the vibration when the main shaft is rotated at a high speed is measured, foreign matter caught between the tool holder and the main shaft is large, and Insufficient clamping may cause problems such as dropping of the tool holder. Therefore, the present invention provides a tool holder eccentricity detecting device that solves the above-mentioned problems.

[0005]

An eccentricity detecting device for a tool holder detachably mounted on a main shaft of a machine tool according to the present invention is provided at an automatic tool change position of a machine tool, and is newly mounted on the main shaft. An eddy current sensor head disposed in a non-contact manner opposite to the flange portion, and a means for detecting a change in impedance formed between the sensor head and the flange portion of the tool holder. The eccentricity of the tool holder is detected by measuring a change in impedance when the tool holder is rotated.

An eddy current sensor head is disposed on the front end surface of a headstock of a machine tool and is disposed in a non-contact manner facing a flange portion of a tool holder mounted on the spindle, and the sensor head and the tool holder. A means for detecting a change in impedance formed between the tool holder and the flange portion, and detecting the eccentricity of the tool holder by measuring the change in impedance when the main shaft is rotated.

The rotation speed of the spindle when measuring the eccentricity of the tool holder is 30 to 750 rotations per minute.
Preferably, it is about 600 revolutions per minute.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 5 is an explanatory diagram showing the principle of the eddy current sensor used in the present invention. The eddy current sensor generally denoted by reference numeral 1 includes a sensor unit 10 and a conversion unit 20.

The sensor unit 10 has a sensor coil 12,
The sensor coil 12 has a magnetic field line M₁To generate a magnetic field
You. The conversion unit 20 has an oscillator 22 and detects a high frequency
Supply to coil 12. The height generated by the sensor coil 12
The frequency magnetic field is measured by an object T ₁Eddy current
Flow A₁Generate.

[0010] impedance proportional to the distance between the measurement target T ₁ of the sensor coil 12 and the conductive steel body changes. The characteristic L of the sensor coil 12 and the capacitor 26
The characteristic C, an LC resonance circuit, the LC resonance circuit detects an output impedance which occurs between the sensor coil 12 and the measurement object T _1. The output high-frequency detector 30, through a linearizer 32, and amplified by an amplifier 34 to obtain the output _{P 1.}

[0011] By detecting the change in the output P _1, it is possible to detect the relative change in a distance between the sensor coil 12 and the measurement object T _1. According to the present invention, an eccentricity detecting device for a tool holder is configured using an eddy current sensor having the above principle.

FIG. 1 is an explanatory diagram showing a configuration near a spindle head of a machine tool provided with a tool holder eccentric device of the present invention,
FIG. 2 is a bottom view of FIG. Machine tool headstock 100
Is attached to an appropriate saddle or the like, and moves relatively to a table (not shown).

The spindle 110 supported by the headstock 100 includes:
It has a shank hole at the tip and is engaged with the tool holder 120 by two claws 112. The tool holder 120 has an appropriate nominal diameter, and is exchanged for the main shaft 110 by an automatic tool exchanging device (not shown). The tool holder 120 has a cutting tool 130 and performs necessary processing on a work on the table.

An eddy current sensor generally indicated by reference numeral 200 is a sensor head 21 inserted into a cylindrical main body 212.
Has zero. The main body 212 is supported by the holder arm 250 by a nut 230 or the like.
Is attached to the support structure 260. Sensor head 2
The signal detected by 10 is sent to the conversion unit via signal line 220.

The tool holder 120 has a flange portion 122 having a maximum diameter. At the automatic tool change position, the eddy current sensor head 210 is arranged at a position facing the flange portion 122 of the tool holder 120.
At this time, the gap _{G 1} of the flange portion 122 of the tip and tool holder of the sensor head 210 is formed, for example, 2m
m. When the main shaft 110 is rotated at a low speed in this state, the flange portion 122 of the tool holder rotates with respect to the sensor head 210.

[0016] When the gap _{G 1} is changed, the sensor head 21
The impedance formed between 0 and 0 changes, and the eccentric rotation of the flange portion 122 can be detected by the operation described above. When the amount of eccentricity exceeds a predetermined value, it is determined that a clamping error has occurred due to a bit of chipping between the tool holder 120 and the main shaft 110, and the main shaft 110 is stopped. I do.

In detecting the eccentricity of the tool holder,
Since the measurement is performed while the spindle is operated at a low speed such as 30 to 750 rotations per minute, troubles such as dropping of the tool holder do not occur even when the tool clamp is not normal. Also, the eccentricity can be detected in a measurement time of about 0.5 seconds.

FIG. 3 is an explanatory view showing another embodiment of the present invention, and FIG. 4 is a right side view of FIG. The headstock 300 rotatably supports the spindle 310, and a tool holder 320 is detachably inserted into the spindle 310. The eddy current sensor generally designated by reference numeral 400 has a sensor head 410 inserted into a cylindrical main body 412.

The main body 412 is attached to the bracket 420 by a nut 430. The bracket 420 is fixed to the front end surface 302 of the headstock 300 by bolts 422.

The sensor head 410 is connected to the tool holder 32
It is placed in a position to hold the gap G ₁ with respect to 0 of the flange portion 322. Then, to detect the change in the gap _{G 1} between the flange portion 322 of the tool holder 320, the signal line 44
0 to the control device to detect abnormal clamping of the tool holder 320 and the like. In this device, the eddy current sensor 400 is attached to the headstock 300 and the headstock 30
Moves with 0.

Therefore, it is possible to detect an abnormal clamping of the tool holder by using a time zone in which the headstock is moving away from the tool change position to the machining section. Further, it becomes possible to monitor the behavior abnormality while the tool holder is performing the machining.

[0022]

As described above, the present invention detects the change in the impedance formed between the eddy current sensor and the measurement object made of the conductor and detects the change in the distance between the eddy current sensor and the measurement object. A device for detecting the eccentricity of the tool holder clamped to the spindle by utilizing the function of detecting the change of the tool holder in a non-contact manner.

The configuration of the eccentricity detecting device is simple and can be easily installed in the space around the spindle head of the machine tool. In addition, the rotational speed of the spindle at the time of the eccentricity measurement is about 30 to 750 rotations per minute, so that there is no problem even in the case of a tool clamping failure. Also, the measurement time is only about 0.5 seconds, so that the efficiency is high.

The flange portion of the tool holder for measuring the run-out is manufactured to the dimensions specified in the respective standards (ISO, CAT, MAS, HSK, etc.). Even the holder being used can be easily detected.

It is also possible to detect the presence / absence of a tool after performing a tool change. This is because, for example, a high-speed rotation of a clamp unit or the like of an HSK without a tool may damage the collet itself, and can function as a method for preventing this.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

FIG. 2 is a bottom view of FIG. 1;

FIG. 3 is an explanatory view showing another embodiment of the present invention.

FIG. 4 is a right side view of FIG. 3;

FIG. 5 is an explanatory view showing the principle of an eddy current sensor used in the present invention.

[Explanation of symbols]

 Reference Signs List 100 headstock 110 spindle 120 tool holder 122 flange 130 cutting tool 200 eccentricity detection device 210 eddy current sensor

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hideo Kosuge No. 1, Oguchi-machi, Oguchi-cho, Niwa-gun, Aichi Prefecture F-term in Yamazaki Mazak Co., Ltd. headquarters factory (reference) 3C029 AA02 AA21

Claims (3)

[Claims] An eccentricity detecting device for a tool holder detachably mounted on a main shaft of a machine tool, wherein the eccentricity detecting device is disposed at an automatic tool changing position of the machine tool and faces a flange portion of a tool holder newly mounted on the main shaft. And an eddy current sensor head arranged in a non-contact manner, and means for detecting a change in impedance formed between the sensor head and the flange portion of the tool holder, and the impedance of An eccentricity detecting device for a tool holder of a machine tool for detecting eccentricity of a tool holder by measuring a change. 2. An eccentricity detecting device for a tool holder detachably mounted on a main shaft of a machine tool, wherein the eccentricity detecting device is disposed on a front end surface of a headstock of the machine tool and faces a flange portion of a tool holder mounted on the main shaft. Current sensor head disposed in a non-contact manner, and means for detecting a change in impedance formed between the sensor head and the flange portion of the tool holder, and a change in impedance when the main shaft is rotated. An eccentricity detecting device for a tool holder of a machine tool for detecting eccentricity of a tool holder by measuring the eccentricity of the tool holder. 3. The tool holder of a machine tool according to claim 1, wherein the rotation speed of the main shaft when measuring the eccentricity of the tool holder is 30 to 750 rotations per minute, preferably about 600 rotations per minute. Eccentricity detection device.