JPS61274850A - Method and device for setting original point of machining in machine tool - Google Patents

Abstract

PURPOSE:To determine the positioning of relative positions between a main spindle and a work fixture with high accuracy by detecting the quantity of deviation between a workpiece and a cutting tool in the axial direction in a transfer machine by means of a machining original point setting device and removing said quantity of deviation by moving said main spindle. CONSTITUTION:A carriage 2 is moved to a defined position by means of the control part of a transfer machine 1. Then, the rod of a measuring member 11 is advanced and brought into contact with the reference surface 3A of a work fixture 3. At this time, the quantity of deviation in the axial direction between the reference point A of the measuring member 11 and the reference point B of a main spindle 4, is detected by a detector 12. And, a position at which the distance between the reference surface 3A of the work fixture 3 and the end of a cutting tool 6 is l, is determined a machining original point. When the reference point B of the main spindle 4 has shifted deltaz from the reference point A of the measuring member 11, the carriage is moved with the measuring member 11 kept in contact with the work fixture 3, until the reference point B agrees with the reference point A. Thereby, the position at which the reference points A and B agreed with each other is determined a machining original point, to start the machining of a workpiece 8.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention is a processing method suitable for determining a relative reference position between a workpiece and a cutting tool during processing in a machine tool that processes a workpiece by numerical control. This invention relates to an origin setting method and device.

[Background of the invention]

In numerically controlled machine tools, such as transfer machines, the workpiece machining process is divided into several parts, and each divided process is performed at each station. is configured to move.

However, when the workpiece fixture is attached to a moving table, there is a risk of installation errors or positioning errors due to movement between stations.

On the other hand, the main shaft to which the cutter is attached is attached to the reciprocating table via a bearing, but it expands due to heat generated by the bearing, so there is a risk of it stretching in the axial direction.

When such elongation of the spindle and positional displacement of the workpiece fixture occur, the axial distance between the spindle and the workpiece fixture changes over time, making it impossible to process the workpiece with high precision.

2. Description of the Related Art Conventionally, when machining a workpiece, a known technique is disclosed in Japanese Patent Laid-Open No. 57-107755 in which the workpiece and a cutting tool are brought into direct contact and the contact position can be detected at the start of machining. However, in this known technique, the cutting tool comes into direct contact with the workpiece, so there is a possibility that the cutting tool will be damaged.

[Purpose of the invention]

In view of the above circumstances, it is an object of the present invention to accurately determine the relative axial position of the spindle and workpiece fixture even if there is a positional displacement of the workpiece fixture or a thermal displacement of the spindle. It is an object of the present invention to provide a method for setting a machining origin for a machine tool that allows positioning, and another object of the present invention is to provide a machining origin setting device for a machine tool that can accurately carry out the above method.

[Summary of the invention]

In the method of the present invention, a measuring element that measures the amount of displacement in the main axis direction of the workpiece fixture is brought into contact with the workpiece fixture, and a reference point provided on the measuring element and a reference point provided on either the main shaft or the cutting tool are used. The feature is that the amount of deviation in the direction of the main axis from the point is detected, the main axis is moved in a direction that absorbs the amount of deviation, and this moved position is set as the machining origin, thereby achieving the above purpose. Ta.

Further, the device of the present invention has a reference point and is attached to the carriage so as to be movable in the direction of the main axis, and has a measuring element that measures the amount of displacement of the workpiece fixture in the direction of the main axis, and a measuring element that is attached to one of the main axis and the cutter. a detector capable of detecting the amount of deviation in the principal axis direction between the provided reference point and the reference point of the measuring point at the time the measuring point contacts the workpiece fixture; The present invention is characterized in that it includes means for moving the main shaft in a direction that absorbs the amount of deviation when the amount of deviation is detected.

This made it possible to achieve the above objective.

[Embodiments of the invention]

Embodiments of the present invention will now be described with reference to the accompanying drawings. 1 to 3 show a machine tool equipped with a device for carrying out the method of the invention.

A machine tool 1 shown in the figure is a so-called transfer machine, and includes a reciprocating table 2 and a workpiece fixture 3. The carriage 2 has a main shaft 4 inside thereof, and can be moved in the direction of the main shaft 3 by a control section (not shown). A cutting tool 6 is attached to the tip of the main shaft 4 via a holder 5, and the main shaft 4 is moved in the axial direction while rotating relative to the carriage 2 during processing.

The workpiece fixture 3 is mounted on the table 7 and placed in front of the main spindle 4, and has a workpiece 8 mounted on the front part.

Furthermore, the machine tool is equipped with a machining origin setting device to determine the relative positions of the spindle 4 and workpiece fixture 3 during machining even if the spindle 4 and workpiece fixture 3 are misaligned in the spindle direction. ing.

The machining origin setting device includes a measuring stylus 11 that is movably attached to the carriage 2 in the direction of the main axis and has a reference point A, a reference point B provided on the main spindle 4, and a reference point B and the reference point A. A detector 12 that detects the amount of deviation in the axial direction is provided.

Specifically, the measuring head 11 is composed of an air cylinder installed at a position corresponding to the reference surface 3A of the workpiece fixture 3 of the carriage 2, and the rod lla is moved in the main axis direction by sucking and discharging air. arranged to move. When the carriage 2 is moved to a predetermined position, the rod lla moves forward and comes into contact with the reference surface 3A of the workpiece fixture 3, thereby measuring the amount of displacement of the workpiece fixture 3 in the main axis direction. It is configured. Therefore, when the rod lla of the measuring head comes into contact with the reference surface 3A, the air pressure (not shown) blown forward from the rod lla changes so that the rod lla is controlled to stop immediately, and the control section For example, it is built into the control section of a machine tool.

Further, the rod lla of the probe 11 is provided with a reference point A' at a desired position from the tip.

Furthermore, the air cylinder serving as the probe 11 is made of an alloy with a low coefficient of thermal expansion, such as invar (64% Fe, 36% Ni), so that it is not easily affected by heat.

The reference point B is provided at the tip of the main shaft A.

When the gauge head 11 comes into contact with the reference surface 3A of the workpiece fixture 3, it coincides with the reference point B of the gauge head 11, which serves as a guide for determining the relative position of the workpiece fixture 3 and the main shaft 4. . Therefore, the position of this reference point B may be provided on the holder 5 if the elongation of the main shaft 4 due to heat is taken into consideration.

The detector 12 includes a magnetizing body 12a that is installed on the outer periphery of the reference point B position of the main shaft 4 and generates a magnetic signal, and a magnetizing body 12a that is installed at the reference point A position of the probe 11 and generates a magnetic signal.
A magnetic sensor 12b that detects signals from the magnetic sensor 12b is provided. This detector 12 detects the signal of the magnetizing body 12a when the measuring head 11 comes into contact with the workpiece fixture 3, and detects the reference point A of the measuring head 11 and the reference point B of the main shaft 4 in the main axis direction. The amount of deviation is detected.

Thus, when the detector 12 detects the amount of deviation, means for moving the main shaft 4 in a direction that absorbs the amount of deviation is also provided. Although the means are not shown, the detector 1
2 detects the amount of deviation, the main shaft 4 and the carriage 2 are moved with the measuring head 11 in contact with the workpiece fixture 3 until the reference point B coincides with the reference point A. For example, it is incorporated into the control section of a machine tool. Therefore, the means monitors the input signal to the magnetic sensor 12b of the detector 12, and depending on the characteristics of the input signal, the main shaft 4 is
And the moving direction of the carriage 2 is determined.

Next, an embodiment of the machining origin setting method of the present invention will be described in relation to the operation of the machining origin setting device of the embodiment.

First, the carriage 2 is moved to a predetermined position by the control section of the machine tool, and then the rod of the probe 11 is advanced and brought into contact with the reference surface 3A of the workpiece fixture 3. At this time,
A detector 12 detects the amount of deviation in the axial direction between the reference point A of the measuring stylus 11 and the reference point B of the main shaft 4.

At that time, as shown in FIG.
On the other hand, when the positions of the reference point B of the main spindle 4 match, the matched position, that is, the position where the distance between the reference surface 3A of the workpiece mount 3 and the tip of the cutting tool 6 is Ω is determined as the machining origin. As a result, after the rod lla of the probe 11 is retracted, machining of the workpiece 8 is started.

However, as shown in FIG. 2, when the reference point B of the main shaft A deviates δ2 from the reference point A of the measuring stylus 11, the main shaft 4 is moved in a direction that absorbs this deviation δ2. That is, while the probe 11 remains in contact with the workpiece fixture 3, the carriage 2 is moved until the reference point B coincides with the reference point A.
is moved.

Thereby, the position to which the carriage 2 and the main shaft 4 have been moved, that is, the position where the reference points A and B match, is set as the machining origin, and machining of the workpiece 8 is started.

As a result, the relative position between the workpiece fixture 3 and the spindle 4 is determined, similar to a transfer machine.

Even if the workpiece fixture 3 is displaced in the direction of the spindle due to movement, and even if the spindle 4 is extended in the axial direction,
Regardless of this, the relative positions of both can be determined reliably. Moreover, since the cutting tool does not come into contact with the work unlike the known technology, there is no fear that the cutting tool etc. will be damaged.

Further, in the device of the present invention, the specific structure of the probe 11 and the detector 12 is not limited to the illustrated embodiment, and may be any structure as long as it has the intended function.

〔Effect of the invention〕

According to the method of the present invention described above, a gauge head for measuring the amount of displacement in the spindle direction of the workpiece fixture is brought into contact with the workpiece fixture, and a reference point provided on the gauge head is connected to either the spindle or the cutting tool. The amount of deviation in the spindle direction from the reference point set at Even if the positional accuracy in the spindle direction is disrupted due to elongation of the spindle, the relative position between the workpiece fixture and the spindle can be determined reliably and with high precision regardless of this.

Further, according to the device of the present invention, there is provided a measuring element that has a reference point, is movably attached to the carriage in the direction of the main axis, and measures the amount of displacement of the workpiece fixture in the direction of the main axis, and either the main axis or the cutting tool. a reference point provided on the sensor; a detector that detects the amount of deviation in the axial direction between the reference point and the reference point of the probe; and a detector that absorbs the amount of deviation at the time when the detector detects the amount of deviation. Since it is provided with means for moving the main shaft in the direction, there is an effect that the method of the present invention described above can be carried out accurately.

[Brief explanation of drawings]

Fig. 1 is a cutaway side view showing an example of a machine tool in which a device for implementing the method of the present invention is applied, Fig. 2 is an explanatory view showing a state in which the workpiece fixture and the main shaft are misaligned, and Fig. 3 FIG. 3 is an explanatory diagram showing the positional state of the machining origin after correcting deviation. DESCRIPTION OF SYMBOLS 1... Machine tool, 2... Carriage table, 3... Workpiece fixture, 4... Main spindle, 6... Cutting tool, 8... Workpiece,
DESCRIPTION OF SYMBOLS 11... Measuring head, 12... Detector, A... Reference point of measuring element 11, B... Reference point of main shaft 4. Representative Patent Attorney Tadashi Akimoto Jitsu No. 1 Business 2 Figure 3 Δ

Claims (1)

[Scope of Claims] 1. A gauge head for measuring the amount of displacement in the main axis direction of the workpiece fixture is brought into contact with the workpiece fixture, and a reference point provided on the gauge head and a reference point provided on either the workpiece fixture or the workpiece fixture are placed in contact with the workpiece fixture. A method for setting a machining origin for a machine tool, characterized by detecting the amount of deviation in the direction of the main axis from a reference point that has been determined, moving the main axis in a direction that absorbs the amount of deviation, and setting this moved position as the machining origin. . 2. A machine tool that has a main spindle on which a cutter is to be mounted, a reciprocating carriage that moves in the direction of the main axis, and a workpiece fixture that is placed in front of the main spindle, and that has a reference point and that moves in the direction of the reciprocating table. A gauge head that is movably attached to the stand in the direction of the spindle and measures the amount of displacement of the workpiece fixture in the spindle direction, a reference point provided on either the spindle or the cutter, and a contact between the reference point and the gauge head. a detector capable of detecting the amount of deviation in the main axis direction from a reference point at the time when the probe contacts the workpiece fixture;
A machining origin setting device for a machine tool, comprising means for moving a spindle in a direction that absorbs the amount of deviation when the detector detects the amount of deviation.