SU1243879A1 - Method of producing die sets for pressing hard-to-form materials - Google Patents

Description

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The invention relates to a pressure treatment, in particular to a method of pressing dies for a combustible stamp,

The purpose of the invention is to increase the durability of the dies by compacting the surface layer of their engraving.

The forging dies during the stamping are repeatedly loaded in the forgings and unloaded. In this case, for each cycle, starting from the first, undergo a small plastic deformation accumulating from cycle to cycle, which corresponds to the conditions of cyclic creep. The conditional cyclic creep limit is the most complete characteristic of the limiting state of a stamp and determines its durability, since the value of this index in tool materials is lower than a. go yield limit. Under cyclic creep conditions, tool materials exhibit accelerated creep in the initial stamping period, and as the amount of load increases and when some plastic deformation is achieved (0.2–1%), their creep resistance and roll shrinkage is reduced by two orders of magnitude. Since the durability of the stamp is determined by the value of the accumulated residual (plastic) deformation, in order to increase the durability, they must be subjected to a pressure equal to the conventional cyclic creep limit before the final finishing of the engraving.

The method of making stamps is as follows.

The original billet, obtained by casting, is machined by dimensional and base surfaces. Electrochemical process pre-engraved stamp. Thereafter, the stamp is mounted in an isothermal deformer and heated to a temperature at which the stamp is further operated. A stamp for isothermal stamping is heated to a temperature of deformation of the material of the products being stamped. Stamps that operate under normal conditions, i.e. n is heated or heated slightly, heated to a temperature

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tours that do not exceed the temperature of the stamp material .;

The heated stamp is cyclically loaded under isothermal conditions, imitating a stamping process that corresponds to the conventional limit of cyclic creep of the stamp material. The number of cycles is chosen in accordance with the temperature and speed of loading. The loading is stopped when residual (plastic) deformation is reached in the order of 0.1-1.0%. The dies are removed from the unit for isothermal deformation, cooled and blown with corundum sand. Then the engraving is processed by hand polishing.

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Example. Stamp blanks

.disothermal punching blanks blades of titanium alloy VT 3-1 is cast from heat resistant alloy FSB-K. The base and dimension surfaces are mechanically treated and electrochemically pre-treated with a stamp engraving. After that, the stamp is mounted in the installation for isothermal deformation of the UIDIN type and the alloy W 3-1 870-900 C is heated to the deformation temperature. The stamp material at this temperature has a tensile strength of 75 kgf / mm.

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At the same time in the electric furnace is heated a billet of heat resistant alloy FSB-KP. Before heating the blanket with a protective lubricant coating EVT-25, the billet is heated to a temperature of 0 deformation of this alloy and deformed in a heated stamp before filling the stamp engraving with metal. After that, the billet is removed from the paper and cooled and the protective and lubricating coating is removed from the surface by corundum sand blasting. The workpiece after the blow is placed in the lower stamp. The dies are closed and the vyderzhka necessary to heat the workpiece to the temperature of the dies, then the die is subjected to a cyclic loading with a specific force of 30-40 kgf / mm. The number of loading cycles is in the range of 20-30 cycles, while the residual strain (subsidence of the stamp engraving) for each half of the stamp is 0.1-0.2 mm, or 0.2%. For cyclic loading

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Wife stamps in isothermal devices and final processing of an engraving

Catching can also be used by hand polishing,

master stamp, made from the application of the invention in comparison with the material, as the stamp. The stamping with the prototype allows to extract from the plant, cool, increase the resistance of the dies when isothermally blown with corundum sand by 3.5–4 times.

Claims (1)

METHOD FOR PRODUCING DIES FOR STAMPING DIFFICULTY DEFORMABLE MATERIALS, machining the basic and dimensional surfaces of die cast blanks, electrochemical and mechanical processing of engraving and its subsequent processing by compaction of the surface layer by plastic deformation, finalizing the engraving, which the purpose of increasing the durability of the stamps, the sealing of the surface layer of the engraving is carried out by creating cyclically varying stresses in it equal to the conditional yield limit of the cyclic creep of the die preform material, and stop it when the surface layer of the engraving reaches a residual strain value corresponding to the value of the conditional yield stress of the die preform material.