The quality of the hollow piston rod processing technology directly affects the quality of the product. The processing technology and use of the hollow piston rod:
(1) In normal use of the piston rod, the piston rod has to bear the action of alternating loads and the surface has to be reciprocated friction, so the piston rod is required to be both hard and wear-resistant.
(2) Generally, the hollow piston rod is made of 38CrMoALA material, and partly after quenching and tempering treatment and surface nitriding treatment, its core hardness is 28-32HRC, surface hardness is 62-65HRC, so that it has a certain degree of toughness.
(3) The structure of the hollow piston rod is relatively simple, but the ratio of length to diameter is relatively large, so it is a slender shaft part, but the rigidity is not very good. Therefore, in order to ensure its machining accuracy, when machining the piston rod, rough turning and finishing turning should be separated to prevent deformation of the workpiece during the machining process. Also note that the center frame should be used when machining the threads at both ends.
(4) When selecting the positioning datum, all processing procedures must adopt the two-center hole positioning method and unified specifications. This is to ensure the coaxiality tolerance of the parts and the accuracy of each part's mutual position.
(5) When grinding the outer surface, it is easy to produce elastic deformation, which affects the accuracy of the hollow piston rod. Therefore, it is necessary to study the center hole, the center hole should be kept clean, and the tightness with the center should be appropriate, and the lubrication should be good. In addition, the width of the grinding wheel should be narrower to reduce the radial grinding force.
(6) When grinding the taper, the test piece must be ground first, and the taper can only be ground after the test piece is qualified.
(7) In order to ensure the stability of the machining accuracy of the piston rod, manual straightening is not allowed during the whole machining process; during the nitriding operation, the threaded part of the piston rod should be protected by a protective device.
https://www.xhychromerod.com