METHOD FOR MANUFACTURING PISTON WITH NIRESIST INSERT USING ISOTHERMAL STAMPING AND INJECTION MOLDING Russian patent published in 2023 - IPC B21K1/18 B22D15/02 F02F3/10 

FIELD: ICEs.

SUBSTANCE: invention can be used in the production of pistons for internal combustion engines. The method of manufacturing a piston with a ni-resist insert using isothermal stamping and injection moulding involves producing a piston blank. When preparing the piston, in order to accurately fix the ni-resist insert relative to the piston surface and achieve the required adhesion of this insert to the piston material, a ni-resist insert with a diameter exceeding the diameter of the piston by 2–3 mm is installed in the left side of the casting mould. Next, the mould and insert are heated to a temperature of 200°C. After heating due to thermal expansion, the insert is fixed relative to the connector plane mechanically by closing the left part of the mould with the right. After which a funnel is installed, heated to a temperature of 400°C. A filling bowl with a stopper is installed on the funnel, also heated to a temperature of 400°C. Next, the aluminium alloy, with a temperature 200 K higher than the temperature at which crystallization begins, is poured into the pouring bowl. After which the vacuum system is turned on and the mould is evacuated, the stopper is undermined and the melt enters the mould at a speed of 1 l/s. Next, the melt is compressed under a pressure of at least 250 MPa. Compression is carried out by pressing plungers moving towards each other for 20 s until the crystallization process is completely completed. After the crystallization process, the workpiece is removed. To speed up the process of crystallization and cooling of the workpiece, water cooling is used; for this, the workpiece is removed and cooled in water to a temperature of 20-25°C. After this, the workpiece, punch and matrix are preliminarily subjected to thermal action, heated to a temperature of 490-500°C, induction method in a separate induction furnace or built-in heating chamber of a hydraulic press. Next, isothermal stamping is carried out at 480-490°C at a deformation rate of 10 mm/s until the piston blank is completely formed. Then, directly from the stamp, the piston blank is transferred to a quenching tank for cooling. Next, aging is carried out for 8-10 hours at 210°C. After this, mechanical processing of the internal combustion engine piston blank with a ni-resist insert is carried out to the required dimensions in accordance with the technical and design documentation using turning and milling equipment. Next, a two-layer thermal barrier ceramic coating is formed on the bottom and skirt of the internal combustion engine piston using the micro-arc oxidation method. The first wear-resistant layer with a thickness of 40-50 microns is formed on the piston skirt. A second, porous thermal barrier layer, 100-150 microns thick, is formed at the bottom of the piston.

EFFECT: simplifying the manufacturing process of a stamped piston with a niresist insert with improved strength, load, and temperature characteristics.

1 cl, 14 dwg