SU1366302A1 - Apparatus for monitoring cutting temperature - Google Patents

Description

The invention relates to a machine tool industry and can be used to indirectly control the load on tools, for example, in turning, boring, milling machines.

The purpose of the invention is to improve the accuracy of temperature control by taking into account the coefficient of emissivity of the surface of the workpiece during heating.

The drawing schematically shows the device.

A device for monitoring the cutting temperature when machining part 1 by a cutter 2 fixed in the tool holder 3 contains a bracket 4 on which it is rotatable in a horizontal plane. A focusing optical head 5 connected to a photoelectric sensor 7, to the photoelectric sensor output is installed 7 connected unit

8 divisions, the first functional converter 9. One of the outputs of the first functional converter

9 through the second functional converter 10 is connected to the second input of the dividing unit 8. The second output of the first functional transducer 9 is connected to differentiation unit 11, multiplication unit 12 and further

.to threshold element 13.

The device works as follows.

Before machining, bring the tool holder 3 with the cutter 2 and the bracket 4, on which the focusing optical head 5 is fixed, to the part 1. The focusing optical head 5 is directed at a certain point of the cutting zone in front of the cutter 2 and fixed on the bracket 4. Range The wavelengths of operation of the optical head 5 are chosen in such a way as to minimize the absorption of infrared radiation by the atmosphere, for example, 0.65, 2.19, 3.9 microns. The mirror objective of the optical head 5 allows infrared radiation to be removed from the area

4 I

TO 1 MM.

Heating part 1 during processing leads to a change in the emissivity of its surface, which depends on temperature. The infrared radiation energy perceived by the focusing head 5 is determined by the exhalation

E, C jQr-ree))

five

0

0 p.

g

five

where, o, r (Tpgj) is dependent on the cutting temperature Tre, the emissivity of its surface, Ed (Tre is the radiation energy of an absolutely black body at the cutting temperature.

The output voltage U d of sensor 7 due to the linear feedback of the optocoupler is proportional to the measured photocurrent, i.e. thermal radiation of the cutting zone.

The uncertainty of the emissivity of the surface of the workpiece, which is always less than 1, leads to the fact that the photoelectric sensor 7, which is graduated according to the black body model, measures the cutting temperature less than a few tens of degrees.

A signal from the output of sensor 7, proportional to the temperature of the cutting zone, is fed to the input of dividing unit 8, which is divided by the output signal of second functional converter 10 to the second input of dividing unit 8. The output signal of second functional converter 10 is connected with its input signal dependence, corresponding to 6,, o, r (Tpej). This dependence is determined in advance and refined experimentally with respect to the radiation properties of the grades of workpieces being processed. This dependence is realized by the converter 10.

The output signal of dividing unit 8 is fed to the input of the first functional converter 9, where it is converted in accordance with the calibration characteristic of sensor 7 directly into the signal V (Tpej), proportional to the true cutting temperature, taking into account the uncertainty of the coefficient g of the emissivity of the surface 1. Parts -10 carry out an iterative process of determining the temperature, since the signal from the output of sensor 7, characterized by Trres less true, since it is not known b, is fed to the input of block 8 neither In block 8, this signal is divided into a signal characterizing - approximate, and from the output of block 8,

to the input of the first functional converter 9. In accordance with the calibration characteristic of the sensor 7 and from the output of the first converter 9, it is again fed to the input of the second converter 10, rea: bzag dependence (Tree), i.e. the signal from the output of sensor 7, which characterizes the temperature less than the true ,. iteratively approaches the signal characterizing the true cutting temperature.

At the output of the differentiation unit 11, the voltage is proportional to pro. A v (Tpe3)

izvodnoi X- - - gradient theme t

perature. Signals from the output of the first functional converter V (T 33) and from the block 11 av (Tpe5) 3t are fed to the input of the multiplication unit 12.

The signal at the output of block 12 multiplication is proportional to the product

VCTpe,)

E V (,) -.

At tool overloads the signal level

V (T) .e3.) VUpe,; uh

abruptly exceeds the threshold of threshold element 13, which is selected from

Conditions for the detuning of the maximum value in normal cutting conditions. After item 13 triggers. the tool feed is stopped.

I

Claims (1)

Formula of Invention A device for controlling the cutting temperature, containing a focusing optical head mounted for rotation on a bracket rigidly fixed in the tool holder, pkd) to the optical head. A photoelectric sensor, a series-connected differentiation unit, a multiplication unit and a threshold element, characterized in that, in order to improve accuracy, a serially connected dividing unit and a first functional converter and a second functional converter, input are introduced into the device between the photoelectric sensor and the differentiation unit. which is connected with the output of the first functional converter, and the output is connected with the second input of the division unit, while the second input of the multiplication unit is connected with the output m first functional converter. .