Sewing Machine Accessories

Usage: Presser foot lifting frame, presser foot rod guide seat, pattern machine needle bar chute assembly, trimming cylinder joint, limiting assembly, cloth feeding shaft crank, mop wheel frame, upper cloth feeding tooth frame, main feeder shaft drive connecting rod, thimble piece fork, thimble piece holder, pick-up connecting rod, etc.

Material: 20Cr steel is one of the most widely produced alloy structural steels in China, which is very widely used. The hardness is higher, and the toughness is worse than 15CrA. The steel has good hardenability, medium strength and toughness. The hardenability of oil quenched to semi-martensitic hardness is 20-23mm in diameter, and after the 20Cr steel is strengthened by carburizing and quenching surface, fine needle-like tempered martensite will be obtained on the surface of the mold, and the hardness is 58-62HRC; The core obtains a low-carbon martensitic structure, hardness of 35-40HRC, and high strength and toughness of the matrix, which can meet the performance requirements of high hardness, high strength, high toughness and appropriate corrosion resistance of cold work molds. Normalizing can promote tissue spheroidization, refine large bulk pre-eutectic ferrites, and improve the machinability of the embryo.

20CrMo hot-rolled steel pipe is a kind of steel pipe product made of alloy. The performance of 20CrMo hot-rolled steel pipe with high temperature resistance, low temperature resistance and corrosion resistance is not comparable with other seamless steel pipes, so alloy pipes are widely used in petroleum, aerospace, chemical industry, electric power, boilers, military and other industries. The main advantages are high hardenability, no tempering brittleness, quite good weldability, little tendency to form cold cracks, good machinability and cold strain plasticity. It is generally used in the state of quenching and tempering or carburizing and quenching. 20crmo hot-rolled steel pipe. The main implementation standards are GB3088-82 (seamless steel pipe for automobile half-shaft casing), GB9948-2006 (seamless steel pipe for petroleum cracking), GB5310-2008 (seamless steel pipe for high-pressure boiler), etc.