JPH06190687A - Thermal displacement correcting device for machine tool - Google Patents

Abstract

PURPOSE:To accurately correct thermal displacement of a machine tool so as to improve machining accuracy by measuring temperature in respective the wholes of a machine tool and a work by means of a radiation temperature measuring device, and computing a correcting quantity against each measured temperature based on a thermal displacement correcting function by means of a thermal displacement corrector. CONSTITUTION:The temperature of many part positions of each the whole of a machine tool 6 and a work 10 is measured by means of a radiation temperature measuring device 7 in non-contact state, and temperature data theta1-thetan of measured respective part positions are output to a thermal displacement corrector 8. A plurality of accurate thermal displacement correcting functions used for the boundary condition of a finite element method is set in the thermal displacement corrector 8, and a plurality of correcting quantities DELTAcx, DELTAcy, DELTAcz are accurately computed along the three axes of X, Y, Z by the use of a decided plurality of formulas. Further a NC device 9 corrects by respective correcting quantities DELTAcx-DELTAcz, and outputs a plurality of operation commands Px, Py, Pz to move along respective axial directions to the machine tool 6. The machine tool 6 works the work 10 in response to the respective operation commands Px-Pz.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal displacement correction device for machine tools.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 2, a plurality of (six in this example) temperature sensors 2 are attached to a machine tool 1,
The temperature sensor 2 outputs temperature signals T1 to T6 indicating the temperature of each part. The temperature signals T1 to T6 are converted into temperature data θ1 to θ6 by the converter 3. The thermal displacement corrector 4 calculates the correction amounts Δcx, Δcy, and Δcz along the three axes of X, Y, and Z using the following equations (1) to (3).

[0003]

## EQU1 ## Δcx = f (θ1 to θ5) (1) Δcy = g (θ1 to θ5) (2) Δcz = h (θ1 to θ5) (3) where f, g, and h are correction amounts. It is a thermal displacement correction function that calculates the, and is created based on a physical model showing the thermal displacement of a machine.

The NC device 5 corrects the correction amounts Δcx, Δcy and Δcz along the X, Y and Z axes and outputs the operation commands Px, Py and Pz in the respective axial directions to the machine tool 1.

[0005]

When the displacement is calculated from the measured temperature by the formulas (1) to (3), it is necessary to increase the number of temperature data to be measured in order to calculate the displacement with high accuracy. .

However, increasing the number of the sensors 2 has a limit because the number of the sensors 2 and the wiring from the sensor 2 to the converter 3 are increased.

Therefore, the thermal displacement correction function based on the high precision physical model such as the finite element method capable of highly precise thermal displacement correction cannot be used because the number of temperature data points is small. For this reason, there has been a problem in that the thermal displacement correction function based on a simple polynomial approximation has to be used, and the accuracy of thermal displacement correction cannot be improved.

SUMMARY OF THE INVENTION In view of the above-mentioned prior art, it is an object of the present invention to provide a thermal displacement correction device for a machine tool capable of accurately performing thermal displacement correction.

[0009]

SUMMARY OF THE INVENTION The structure of the present invention for solving the above problems includes a radiation temperature measuring device for detecting temperatures at a large number of points of a machine tool and a work and outputting temperature data indicating temperatures at the respective points. A thermal displacement correction function capable of accurate thermal displacement correction is set, and a thermal displacement compensator that takes in the temperature data and uses the thermal displacement correction function to calculate a correction amount for correcting thermal displacement, and the correction amount And an NC device that sends an operation command corrected by the amount to the machine tool.

[0010]

In the present invention, since the temperature of the machine tool and the entire work can be detected by the radiation temperature measuring device, the thermal displacement compensator adopts a highly accurate thermal displacement compensation function to obtain an accurate compensation amount. Includes an operation command to the machine tool.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. In this embodiment, the radiation temperature measuring device 7 is used to make the entire machine tool 6 and the workpiece 1.
The temperature of a large number of 0 parts is measured in a non-contact manner, and the temperature data θ1 to θn of the respective parts are output to the thermal displacement corrector 8. In this case, the radiation temperature measuring device 7 is of a type that can display light and shade or color-coded display on the TV screen depending on the temperature, that is, a type that can measure the temperature of each point of the entire machine tool 6 and the entire workpiece 10 at once. Use one. As a result, it is possible to obtain temperature data of a large number of points necessary for highly accurate thermal displacement correction without increasing the number of temperature sensors and wirings.

In the thermal displacement compensator 8, highly accurate thermal displacement compensation functions F, G and H used for the boundary condition of the finite element method are set. This thermal displacement compensator 8 has a large number of temperature data θ.
1 to θn are taken in and using the following equations (4) to (6),
Correction amounts Δcx, Δcy, Δcz along the three axes of X, Y, and Z
With high accuracy.

[0014]

## EQU2 ## Δcx = F (θ1 to θn) (4) Δcy = G (θ1 to θn) (5) Δcz = H (θ1 to θn) (6)

The NC device 9 corrects the correction amounts Δcx, Δcy, and Δcz along the X, Y, and Z axes, and outputs the operation commands Px, Py, and Pz to move along each axial direction to the machine tool 6. The machine tool 6 operates based on the operation commands Px, Py, Pz to process the work 10.

In this embodiment, the correction amounts Δcx, Δcy, Δc
z can be calculated with high precision, and this correction can be performed by the machine tool 6
Not only the thermal displacement of the work 10 is included, but accurate machining can be performed.

In the above embodiment, the thermal displacement correction function by the finite element method is set in the thermal displacement compensator 8. However, thermal displacement based on a high precision physical model by another method capable of highly precise thermal displacement correction is set. A correction function may be set.

[0018]

According to the present invention as described in detail with the embodiments above, the thermal displacement of the machine tool can be corrected with high accuracy, and the machining accuracy of the machine tool can be improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a conventional technique.

[Explanation of symbols]

 1,6 Machine tool 2 Temperature sensor 3 Converter 4,8 Thermal displacement compensator 5,9 NC device 7 Radiation temperature measuring device 10 Work

Claims (1)

[Claims] 1. A radiation temperature measuring device for detecting temperatures at a large number of points of a machine tool and a work and outputting temperature data indicating temperatures at the respective points, and a thermal displacement correction function capable of highly accurate thermal displacement correction are set. A thermal displacement compensator that takes in the temperature data and uses the thermal displacement compensation function to determine a compensation amount for compensating for thermal displacement, and an NC device that sends an operation command compensated by the compensation amount to a machine tool. A thermal displacement correction device for a machine tool, comprising: