SU1205967A1 - Method of heated drawing - Google Patents

Description

one

The invention relates to the processing of metals by pressure, in particular to methods of drawing with heating.

The purpose of the invention is to improve the quality by creating a uniform temperature field along the contour of the workpiece.

Phg r. Is a diagram of the device for implementing the method; figure 2 - heating scheme of the workpiece; FIG. 3 shows the nature of the temperature distribution of the heated billet in the radial direction; Fig. 4 is a diagram of the connection of the workpiece when heated from a single transformer.

A device for implementing the method comprises a punch 1, a pressure ring 2, a matrix 3, electrical contacts 4, a blank 5, a technological allowance 6 for trimming, a finished product 7.

The method is carried out as follows.

A flat square billet 5 is placed between the die 3 and the pressure ring 2.

To the corner zones of the workpiece 5 connect two pairs of electrical contacts 4 successively a series of plus or minus. Each pair of opposite electrical contacts is powered from autonomous sources (not shown), the voltage of which is in phase. This allows the use of current to be shorter than the length of current leads in the circuit with one power source and provides energy savings due to lower power losses current leads ..

For the purpose of uniform heating of the workpiece along the perimeter (in the tangential direction they create equal drops of voltages per unit distance between electrical contacts. This is achieved by changing the distance between the contacts before heating the workpiece.

When an electric current is passed through the workpiece, the current flows through it in the tangential direction, due to which the workpiece is heated to a predetermined temperature.

When the working stroke of the clamping ring 2, mounted on the outer slide of the press (not shown, cuts the technological allowance 6 with its cutting edge, disconnecting the electrical contacts 4 from the workpiece 5.

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Further, the ring 2 is pressed against the flange portion of the workpiece 5 to the matrix 3, and the punch 1, mounted on the inner slide (not shown),

5, apply the deformation forces to the central part of the workpiece, obtaining the finished product 7,

Example 1. Heat and deform ring sheet blanks

10 with a diameter of 220 mm of titanium alloy with a thickness of 1.2 mm. Heating is carried out from a step-down transformer. Use alternating current of industrial frequency. Primary voltage

15, the transformer winding is 380 V. The connection diagram of the transformer to the workpiece is shown in FIG.

Additional contacts are connected to the main via a check 20. The jumpers create additional resistance in the circuit for supplying electrical current to the contacts 4. This causes a difference in the voltage drop between the contact pairs.

25 4-4 and 8-8 and, accordingly, the difference in temperature fields of heating.

The equality of the voltage drops between the contacts between the contacts is ensured by changing the distance between the contacts:

30 between pins 4–4, the distance increases, and between pins 8–8 decreases until the voltage drops between the pins are equal. As contacts use

35 copper and graphite plates with a diameter of 60 mm.

The temperature is measured with a thermocouple, photodiode sensor, and also recorded with a twelve -40-catio oscilloscope. The intensity of the heating is changed by varying the voltage on the secondary winding of the transformer (by switching the switches).

45

The difference between the heating of the center of the workpiece and the flange is 450-500 C. With an increase in the heating time at the same voltage

50, the nature of the distribution of the temperature fields is maintained, and the difference in the heating temperatures of the center and the flange of the workpiece is reduced.

By increasing the heating rate

55 (increasing the potential difference between the contacts), the nature of the distribution of temperature fields is also generally preserved. However the difference

The temperatures of the center of the flow rate and the flange increase.

Measurements of the temperature in the tangential direction at the same distance from the center of the billet show that, with the exception of the zones on the other hand, which are thin under the contacts, the temperature difference is the temperature of the zones of the billet under the contacts that are lower than contact zones at 350-400 ° C.

During deformation of ring blanks with uneven heating of the flange zone, separation from the flange of the sub-contact, relatively little heated zone of the workpiece occurs, which reduces the quality of products and limits the ability of the method.

PRI mme R 2. Heated and deformed rectangular sheet billets with dimensions of 220 x 220 mm made of titanium alloy with a thickness of 1.2 mm. Heat

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loans from two transformers according to the wiring diagram shown in figure 2.

The nature of the temperature distribution of 5 Hf fields in the radial direction (Fig. 3) remains unchanged, and the temperature difference between the heating center and the flange of the workpiece is 400-450 ° C. The extraction is carried out on a double-action hydraulic press

using a combined stamp.

The advantages of the proposed method in improving the quality of products due to

15 uniform deformations over the product profile, increasing the degree of stretching, punching accuracy, making parts of unlimited size from high-strength steels and titanium alloys, reducing the number of die tooling, and energy consumption for heating and shaping.

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Claims (1)

DRAWING METHOD WITH HEATING, which includes applying deformation forces to the central part of the workpiece, pressing the flange part, passing electric current through the workpiece by connecting at least two pairs of electrical contacts * sequentially alternating plus or minus, characterized in that, in order to increase the degree of drawing - .and improving the quality of finished products during heating create the equality of voltage drops per unit length of the distance between the electrical contacts, the power of each pair of opposite electrical contacts about uschestvlyayut from independent sources, voltages which are in phase, .a before pressing onto the flange portion of the preform heating is stopped by disconnecting it from the electric contacts _β cutting portion of the workpiece in the electric area trokontaktov ®. 1 // ¾ £ in b sl m