JP2001300836A - Tool positional displacement correcting machining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tool positional displacement correcting machining method capable of instantly feeding back edge positional displacement of a tool for correcting a workpiece. SOLUTION: In this tool positional displacement correcting machining method for machining the workpiece while correcting positional displacement of a machining part of the tool T installed on a main spindle 1 of a numerical control machine tool, the numerical control machine tool is provided with a temperature detecting process for detecting a temperature change in the main spindle 1, an anticipating process for anticipating displacement of the machining part of the tool from a temperature detected in the temperature detecting process on the basis of the relationship between the premeasured temperature change in the main spindle and the positional displacement of the machining part of the tool and a machining process for performing work while driving respective shafts of X, Y and Z of the numerical control machine tool so as to correct a displacement quantity anticipated by this anticipating process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for correcting a tool position displacement for a numerically controlled machine tool such as a machining center, while correcting a tool position displacement caused by a thermal expansion of a main spindle. is there.

[0002]

2. Description of the Related Art Conventionally, a tool length and a tool diameter of a tool mounted on a spindle of a numerically controlled machine tool are measured when the tool is not rotating, and the values cannot be changed until the end of machining.

However, with the recent increase in the speed of the spindle of a numerically controlled machine tool, it has been found that the position of the tool is displaced during machining due to thermal deformation of the machine due to heat generation of a bearing portion of the spindle, extension of the spindle, and the like. .

In the conventional method of measuring a tool during non-rotation, there has been a problem that the displacement of the tool due to the rotation of the spindle of the numerically controlled machine tool affects the machining, and the accuracy of the workpiece cannot be maintained.

Therefore, a proposal has been made for measuring the tool length, tool diameter, deviation of the center position of the tool, the shape of the tool tip, etc. of the rotating tool to obtain the displacement of the tool edge position.

For example, the technique disclosed in Japanese Patent Application Laid-Open No. Hei 10-138097 relates to a method for measuring a tool dimension which makes it possible to measure a displacement of a blade edge position of a tool in a non-contact manner by a laser beam.

[0007]

However, in the technique disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 10-138097, although the displacement of the cutting edge position of the rotating tool can be measured automatically and quickly, the displacement is measured. It is difficult to immediately feed back the edge position displacement to the correction of the processing of the workpiece.

Accordingly, the present invention has been made in view of the above-mentioned problem, and an object of the present invention is to provide a tool position displacement correction machining method capable of immediately feeding back the tool edge position displacement to the correction of a workpiece. To provide.

[0009]

Means for Solving the Problems To solve the above-mentioned problems,
In order to achieve the object, a tool position displacement correction processing method according to the present invention is directed to a tool for processing a workpiece while correcting a position displacement of a processing portion of a tool attached to a spindle of a numerical control machine tool. A position displacement correction processing method, a temperature detection step of detecting a temperature change of the spindle, and a previously measured, based on the relationship between the temperature change of the spindle and the position displacement of the processing portion of the tool, A prediction step of predicting the displacement of the machining portion of the tool from the temperature detected in the temperature detection step; and X, Y, and Z of the numerically controlled machine tool so as to correct the displacement amount predicted in the prediction step. And a processing step of performing processing while driving the shaft.

[0010] In the tool position displacement correction machining method according to the present invention, a touch sensor disposed on a table of the numerically controlled machine tool measures a reference tool length in a stationary state of a spindle immediately before the start of machining. It is characterized by further comprising a step.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below.

First, an outline of an embodiment will be described.

The position displacement correcting machining method for a tool according to the present embodiment firstly uses the rotational speed of a spindle of a numerically controlled machine tool.
This is achieved by measuring the displacement of each of the X, Y, and Z axes.

The present embodiment is based on the fact that there is a general correlation between the displacement amount and the temperature of the spindle.

This measuring method will be described with reference to FIG.

A precision gauge 31 having a spherical tip is attached to the rotating spindle 1 of the numerical control machine tool. This ball precision gauge 3
For 1, the electric micro-measuring devices 19a, 19b, and 19c are set on the table 5 along the X, Y, and Z axes,
While rotating the rotating main shaft 1 at a predetermined number of revolutions, the displacement δ of each of the X, Y, and Z axes with the change of the time τ is measured.

A temperature sensor 13 is built in the spindle head 3 so as to be close to the rotating spindle 1.
Measurement.

FIG. 3 shows an example of the result.

FIG. 3 shows the relationship between the lapse of time τ due to the rotation of the main shaft and the displacement δ of each axis. The horizontal axis represents time τ, and the vertical axis represents the displacement δ.

When τ = 0, the rotating spindle 1 is 10,000 m
When the rotation is started at in ⁻¹ , the main shaft generates a displacement amount δ due to heat generation of the bearing portion over time.

By measuring this by the above means, the displacement δ of each of the X, Y, and Z axes can be determined.

FIG. 4 shows the result of measurement while changing the rotation speed while setting a constant standby time while changing the rotation speed. From this, it can be understood that the displacement amount δ increases as the rotation speed increases.

By applying the temperature change of the temperature sensor 13 built in the spindle head 3 to FIG. 4, it is found that there is a general correlation.

For example, when the rotation speed of the spindle is 2000 min
Displacement δ when the temperature t of the spindle increases by 1 ° C. in the case of ^-1
And the temperature t of the main shaft when the rotation speed is 10,000 min ^-1.
Is approximately the same as the displacement amount δ when the temperature rises by 1 ° C.

Thus, the displacement data of the displacement δ of each of the X, Y, and Z axes when the temperature t of the main shaft rises by 1 ° C. is collected. This is stored in the reference value storage device 21 as the displacement amount δ for each predetermined unit temperature.

Further, in the present embodiment, in a numerically controlled machine tool having a function of exchanging a tool to be used by a tool exchanging device, a position of an initial state is determined by a detector such as a touch sensor arranged on a table at an initial stage of exchange. If it has been measured, the displacement δ can be predicted by measuring the temperature change with the temperature sensor 13 built in the spindle head 3 thereafter.

Hereinafter, one embodiment of the present invention will be specifically described.

In the following embodiment, a numerically controlled machine tool is provided with a tool changer in the form of a tool holder, and a rotary cutting tool T is rotated from a rotary spindle 1 via a tool holder as shown in FIG. It is configured to be obtained.

FIG. 1 is a block diagram showing the configuration of an embodiment of a numerically controlled machine tool having the function of the tool position displacement correction machining method of the present invention.

In FIG. 1, a numerically controlled machine tool is arranged on a spindle head 3 containing a rotating spindle 1, a table 5 for fixing a workpiece (not shown), and X, Y and Z axes. ,
There are provided feed motors 9a, 9b, 9c for relatively moving the X, Y, and Z axes in accordance with a command from the NC device 7.

A rotary cutting tool T is attached to the tip of the rotary spindle 1. The rotary cutting tool T is rotated to perform desired processing on a workpiece.

First, it is assumed that the tool diameter of the rotary cutting tool T, the length of the run-out tool, and the like are measured in advance by another means. It is stored in each offset memory.

Thereafter, the rotary spindle 1 is rotated at the rotation speed of the rotary cutting tool T to start desired machining.

During machining, the displacement amount δ of the tool edge in each of the X, Y, and Z directions is computed by the computing device 23 from the value of the temperature sensor 13 built in the spindle head 3, and the computed result is corrected by the correcting device. 25, the work coordinate system is corrected, and the work coordinate system is sent to the NC device 7. A machining command is issued from the NC device 7 to the feed motors 9a, 9b, 9c for the X, Y, and Z axes to continue machining.

Further, the tool length of the rotary cutting tool T is measured by the touch sensor 11 installed at a place on the table 5 which does not interfere with the processing immediately before the processing of the workpiece.

A rotary cutting tool T is mounted on the rotary spindle 1,
When the tool length of the rotary cutting tool T is measured by the touch sensor 11 in a stationary state, the tool No. The measured value is stored in the tool length measuring unit 15 every time.

Thereafter, the rotary spindle 1 is rotated at the rotation speed of the rotary cutting tool T to start desired machining.

When a certain processing step is reached, the amount of displacement of the tool edge in the Z-axis direction is calculated by the calculating device 23 from the value of the temperature sensor 13 built in the spindle head 3, and the calculated result is sent to the correcting device 25. NC device 7 as the tool length offset value
And issues a movement command to the Z-axis feed motor 9c.
Work on the workpiece.

As described above, according to this embodiment, the amount of displacement of the rotating tool and the amount of displacement of the tool length are measured by measuring the temperature change of the spindle head 3 so that it can be quickly performed in any process during machining. Can be corrected.

In particular, machining errors due to thermal deformation due to the recent increase in speed of the spindle of the numerically controlled machine tool can be eliminated, and the machining accuracy of the workpiece can be improved.

[0041]

As described above, according to the present invention,
The displacement of the cutting edge position of the tool can be immediately fed back to the correction of the workpiece, and high-precision machining can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a numerically controlled machine tool having a function of a tool position displacement correction machining method of the present invention.

FIG. 2 is a diagram showing a method of measuring displacement amounts of X, Y, and Z axes according to the number of revolutions of a main shaft.

FIG. 3 is a diagram showing a relationship between a lapse of time due to rotation of a main shaft and a displacement amount of each shaft.

FIG. 4 is a diagram showing a relationship between a temperature change due to rotation of a main shaft and a displacement amount of each shaft.

[Explanation of symbols]

 Reference Signs List 1 rotating spindle 3 spindle head 5 table 7 NC device 9a X-axis feed motor 9b Y-axis feed motor 9c Z-axis feed motor 11 touch sensor 13 temperature sensor 15 tool length measurement unit 17 spindle temperature measurement unit 19a X-axis electric micro measurement device 19b Y-axis electric micro-measuring device 19c Z-axis electric micro-measuring device 21 Reference value storage device 23 Computing device 25 Correction device 31 Ball precision gauge T Rotary cutting tool

Claims (2)

[Claims] 1. A tool position displacement correction processing method for processing a workpiece while correcting a position displacement of a processing portion of a tool attached to a spindle of a numerical control machine tool, the method comprising: A temperature detection step to be detected, and a processing section of the tool from the temperature detected in the temperature detection step based on a relationship between a temperature change of the spindle and a positional displacement of the processing section of the tool, which is measured in advance. And a machining step of performing machining while driving the X, Y, and Z axes of the numerically controlled machine tool so as to correct the displacement amount predicted in the prediction step. A tool position displacement correction processing method characterized by the above-mentioned. 2. The method according to claim 1, further comprising a measuring step of measuring a reference tool length in a stationary state of the spindle immediately before the start of machining by a touch sensor arranged on a table of the numerically controlled machine tool. 2. The tool position displacement correction processing method according to 1.