JPS6157143B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a machining method that controls the temperature of a shaft head or a workpiece. The aim is to eliminate the positional error of the center of the machined hole in a workpiece made of a material different from that of the shaft head, and to perform high-precision machining.

Conventionally, thermal displacement due to temperature changes in the shaft head of the processing equipment is a factor that inhibits the machining accuracy of workpieces processed by processing equipment, and in order to eliminate this thermal displacement, lubricating oil is added to the shaft head. The temperature of this lubricating oil was controlled to follow changes in atmospheric temperature to maintain a constant temperature difference.

However, if the material of the workpiece and the material of the shaft head of the processing equipment are different and there is a difference in linear expansion coefficient, control to keep such a temperature difference constant will be difficult to control the thermal expansion of the workpiece and the thermal expansion of the shaft head. Because of the difference in the amount, a positional error in the center of the machined hole will occur when the workpiece temperature reaches room temperature (for example, 20 degrees Celsius) after machining. As shown in Fig. 1, when an aluminum workpiece W is bored at a temperature higher than room temperature using two spindles 2 and 3 supported on a common shaft head 1, the thermal expansion of the workpiece W The amount is larger than the amount of thermal expansion of the shaft head 1. Therefore, when the workpiece returns to room temperature, the amount of shrinkage in dimensions between the machined hole pitches and the center of the machined hole with respect to the workpiece mounting reference surface is the same as between the spindle pitches of the shaft head and the center of the spindle with respect to the bottom surface of the shaft head at the time of machining. The amount of thermal expansion is larger than that of the dimension of , and a negative dimensional error is caused due to the difference in the coefficient of linear expansion between the two.

Furthermore, if the workpiece and the shaft head are machined at a temperature lower than room temperature, there will be a positive dimensional error when the temperature returns to room temperature because there will be a difference in the amount of shrinkage during processing.

The present invention eliminates machining errors caused by differences in linear expansion coefficients caused by differences in the materials of the workpiece and the shaft head by controlling the temperature of the shaft head or the workpiece. The ratio of the deviation of the workpiece temperature with respect to this reference temperature and the deviation of the shaft head temperature with respect to the reference temperature with °C as a reference is the inverse ratio of the linear expansion coefficient of the workpiece material and the linear expansion coefficient of the shaft head material. Processing is now carried out under temperature control.

The details of the present invention will be explained below with reference to the drawings. The processing device 10 shown in FIG. 2 includes a bed 11, a feed unit 12 provided on the bed 11, a slide table 14 slidably guided by a slide surface 13 of the feed unit 12, and a slide base 14 that is slidably guided by a slide surface 13 of the feed unit 12. A shaft head 15 installed on the moving table 14 and a drive device 16 that drives a plurality of spindles supported on the shaft head 15.
and a jig main body 17 which is fixed on the bed 11 and positions and clamps the workpiece W at a predetermined position. Two spindles 18 and 19 are rotatably supported on the shaft head 15 . Shaft head 1
A lubricating oil supply device 20 for supplying lubricating oil into the inside of the shaft head 15 is provided outside the shaft head 15.
0 supplies lubricating oil into the shaft head 15 via a conduit 21 and recovers the lubricating oil via a conduit 22. The lubricating oil supply device 20 is provided with a heater 23 for heating the lubricating oil and a cooler 24 for cooling the lubricating oil, and the temperature of the lubricating oil can be controlled by operating the heater 23 or the cooler 24. , the temperature of the shaft head 15 is adjusted. A first temperature detector 25 is provided on the shaft head 15 and detects the temperature of the shaft head 15 whose temperature is adjusted by temperature-controlled lubricating oil. The jig main body 17 is provided with a second temperature detector 26 for detecting atmospheric temperature. This second temperature sensor 26 is used to indirectly measure the temperature of the workpiece, and when machining is performed by supplying cutting oil to the workpiece, this cutting oil is used to measure the temperature of the workpiece. A second temperature detector 26 may be installed in the cutting oil recovery passage or in the cutting oil storage tank to detect the temperature of the cutting oil, which is applied before machining. In addition, when the temperature of the workpiece can be directly detected, the second temperature detector 26 is provided at a position where it can be detected.

The heater 23 and the cooler 24 are controlled by a control circuit 30.
Controlled by control signals from

The control circuit 30, as shown in FIG.
The temperature t1 detected by the temperature sensor 25 is 20 degrees Celsius.
Amount of temperature change △ with respect to the reference temperature to based on degrees
A calculation circuit 31 that calculates t1, a calculation circuit 32 that calculates the temperature change amount △t2 of the detection signal t2 of the second temperature detector 26 with respect to the reference temperature to, and a calculation circuit 32 that calculates the temperature change amount △t2 from the shaft head 15. A correction value calculation circuit 33 that calculates a correction value △t2' by multiplying the ratio α2/α1 of the linear expansion coefficient α1 of the workpiece W to the linear expansion coefficient α2 of the workpiece W.
and a comparator 34 that compares the temperature change amount Δt1 output from the arithmetic circuit 31 and the correction value Δt2' output from the correction value arithmetic circuit 33. This comparator 34 outputs a control signal for switching the operation of the heater 23 and the cooler 24 so that the amount of temperature change Δt1 with respect to the reference temperature to of the shaft head becomes equal to the correction value Δt2'. When △t1>△t2', the cooler 24 is activated, when △t1<△t2', the heater 23 is activated, and when △t1=△t2', the heater 23 and the cooler are activated. 24 are both stopped. If the amount of heat generated in the shaft head 15 is large, the heater 2
3 does not necessarily have to be provided. If the material of the workpiece W is aluminum, its linear expansion coefficient α2
is (24×10 ^-6 )°C ^-1 , and if the material of the shaft head 15 is cast iron, its linear expansion coefficient α1 is (12×10 ^-6 )°C ^-1
It is. Therefore, the linear expansion coefficient ratio is α2/α1=
2, and △t1 becomes 2・△t2.
As shown in Figure 5, if the workpiece temperature t2 is higher than the reference temperature _t0 , the shaft head temperature is adjusted.
t1 is controlled to be an even higher temperature (to+2・△t2), and when the workpiece temperature t2 is lower than the reference temperature to, the shaft head temperature t1 is controlled to be an even lower temperature (to−2・△t2). t2).

As a result, no matter what the workpiece temperature is, machining can be carried out in a state where the amount of thermal expansion in the distance between the centers of the spindles of the shaft head 15 is equal to the amount of thermal expansion in the distance between the centers of the machined holes in the workpiece. Therefore, if the workpiece temperature returns to the reference temperature to after machining, the distance l between the centers of the machined holes and the distance from the workpiece mounting reference surface to the center of the machined hole become normal dimensions, and the machining error is corrected.

FIG. 4 shows a second embodiment of the present invention,
In the embodiment described above, the difference Δt1 between the detected temperature t1 of the shaft head 15 and the reference temperature to was determined and controlled so that Δt1=2・Δt2, but the detected temperature t1 of the shaft head 15 is applied as it is to one input terminal of the comparator 34, and the amount of temperature change △t2 of the workpiece is input to the other input terminal.
is multiplied by the linear expansion coefficient ratio α2/α1, and the calculation circuit 35 adds the reference temperature to to the correction value.
The difference is that t2' is given and compared with the detected temperature t1.

In this case as well, a thermal expansion equal to the thermal expansion due to the temperature change of the workpiece is generated in the shaft head, and the distance between the machined hole pitch and the center of the machined hole with respect to the workpiece mounting surface at the time of machining is larger by the amount of thermal expansion. Processed into Therefore, when the workpiece returns to room temperature, the machined hole pitch dimensions match the regular dimensions and the machining errors are corrected.

The object to be temperature controlled is not limited to the shaft head only, but the present invention is also effective even when the temperature of the workpiece is controlled. In this case, the workpiece temperature is controlled so that the ratio of the deviation between the workpiece temperature and the shaft head temperature with respect to the reference temperature becomes an inverse ratio of the linear expansion coefficients of the workpiece and the shaft head.

According to the present invention, it is effective for workpieces made of a material different from the material of the shaft head that requires high dimensional accuracy such as machining hole pitch, and greatly improves machining accuracy compared to conventional machining methods. I can do it.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention; FIG. 1 is an explanatory diagram of the principle of the invention, FIG. 2 is a diagram showing a schematic configuration of a processing device, FIG. 3 is a block diagram of a control circuit, and FIG. 4 is a diagram explaining the principles of the present invention. A block diagram of a control circuit as an example of
FIG. 5 is a control characteristic diagram. 10...Processing equipment, 11...Bed, 12...
Feeding unit, 14...Sliding table, 15...Shaft head, 17...Jig body, 18, 19...Spindle, 20...Lubricating oil supply device, 23...Heater,
24...Cooler, 25...First temperature detector, 2
6... Second temperature detector, 30... Control circuit, 3
1, 32, 33...Arithmetic circuit, 34...Comparator.

Claims (1)

[Claims] 1 A method of drilling holes in a workpiece fixed to a jig body using a processing tool installed on a rotating spindle, in which the temperature of the workpiece and the temperature of the shaft head that holds the tool are measured, and the temperature of both temperatures is measured. The deviation from the reference temperature is calculated, and the ratio of the deviation of the workpiece temperature from the reference temperature and the deviation from the shaft head temperature from the reference temperature is calculated as the inverse ratio of the linear expansion coefficient of the workpiece material and the linear expansion coefficient of the shaft head material. A machining method that controls the temperature of the shaft head or workpiece so that