CS195569B1 - Method of increasing the drawing coeficient in the production of hollow parts from the metal-sheet and facility for making the same - Google Patents

Abstract

The process uses a lower die forming a drawing chamber (a) contg. pressurised fluid supplied and/or drained via a valve. Chamber (a) is connected via a channel to a cavity (b) in which a sheet metal blank is placed; and when a punch drives the blank into chamber (a), part of the fluid is driven into the cavity (b), where it exerts pressure on the periphery of the blank. One pref. tool set consists of a lower- and an upper-die fitted with seals to form cavity (b); and chamber (a) has an adjustable drain valve, controlling the exit of fluid and therefore the amt. driven into cavity (b) when the deep drawing punch is lowered. The drawing coeffts. of the metal blanks are increased so the forming capacity of the metal can be fully exploited.

Description

SUMMARY OF THE INVENTION The present invention provides a method for increasing the drawing coefficient in the manufacture of sheet metal hollow components by hydromechanical drawing from blanks by applying an additional pressure to the periphery of the blanks by utilizing the waste liquid pressure of the drawing chamber and apparatus.

In hydromechanical deep drawing, pressurized fluid is used to increase the drawing coefficient by partly stretching and wrapping the stretched portion on the punch at the beginning of the drawing and by relieving the already stretched sheath under tension by the friction force caused by the liquid pressure.

The drawing coefficient is referred to herein as the ratio of the blank diameter to the diameter of the extract, which is achieved during drawing without breaking the extract.

A disadvantage of the present method is that, in particular for non-ferrous metals, the drawing coefficient given by the material cannot be fully utilized.

These drawbacks are substantially eliminated by a method and apparatus for increasing the drawing coefficient in the manufacture of sheet metal hollow parts by hydromechanical drawing from the blank under the application of additional pressure on the circumference and the blank thickness, which is based on the additional pressure being applied to the blank fluid from the draft chamber. The additional pressure is controlled by a control valve.

In this way and with the apparatus, an increase in the drawing coefficient is achieved for extracts which would not be able to be pulled out per operation.

The essence of the method and apparatus is explained with reference to the accompanying drawing, in which Fig. 1 shows schematically in cross-section the beginning and end of a hydromechanical depth drawing on a device for increasing the drawing coefficient using additional liquid waste pressure. on an apparatus for increasing the drawing coefficient using an increased additional liquid waste pressure.

The initial material blank is placed on the active part of the tool, consisting of the drawing chamber 6 with the pressure fluid cavity 6, the pressure holding device 7, the pressure fluid 6. It further comprises a manifold 11, seals 7 and 8 and a control valve 13. The multiplier piston 6 serves to increase the additional pressure. Seals 10 and 11 are then used to seal the pressure. The spring 12 assists in returning the multiplier piston 2 ^{to its} initial position. Pressure control valves are controlled by control valves 13 and 14.

The method and apparatus for increasing the drawing coefficient of sheet metal hollow parts during hydromechanical drawing from blanks are as follows:

The starting blank is, after clamping to the active parts of the tools pulling chamber £ and retainer 3 is pulled hydromechanical by drawing using a punch £ and pressurized liquid 2 · of the excess fluid pressure £ is discharged manifold 2 ^{from the} space pulling chamber £ and acts as a direct additional surface pressure given on Beginning of blanking 2 *

95569 its thickness. The seals 7 and 1 prevent leakage of the pressure fluid 5.

The additional pressure applied to the area given at the beginning of the drawing by the periphery of the blank 1 and its thickness can be applied directly by being transferred through the distribution 6, or its size can be controlled during the drawing by the control valve 13.

However, in order to improve the effect, the additional pressure can be increased, for example, by a multistage piston 2. Also in this case, an increased pressure of the pressurized liquid 5 can be used either directly or regulated by control valves 13 or 14, or both.

The seals 10 and 11 perform the usual function to maintain the pressure of the pressure fluid 5 in the device. The spring 12 assists in returning the muutticator piston 9 to its original position.

Achieving a higher drawing coefficient is particularly important and advantageous for less formable materials and extracts in which, in simple hydromechanical drawing, pulling out in a single operation would not be possible.

The advantages of the invention can be utilized in all mills in which hydromechanical drawing is introduced, in particular in drawing non-ferrous metal sheets.

Claims (3)

SUBJECT A method of increasing the drawing coefficient in the manufacture of sheet metal hollow parts by hydromechanical drawing from blanks under the application of additional pressure to the area given by the perimeter and the thickness of the blanks, characterized in that during drawing. 2. The method according to claim 1, characterized by E N G L IS H by taking the additional liquid pressure. se when acting on the blanks zvysuue. 3. A method for carrying out the method of claim 1, comprising drawing from a traction chamber, a retainer, a punch, a manifold and a seal, wherein the manifold (6) is provided for transferring the additional pressure of the pressurized fluid (5). control valve (13). 1 sheet of drawings