Jai Engineering

Excavator jack hammers are impact devices designed to break any kind of rock or concrete with any hardness or physical property. They have a wide range of applications such as demolition, deconstruction, primary rock excavation, secondary rock breaking, trenching, foundation work, asphalt cutting and many others.With simple but efficient working principle, the purpose of the rock breaker is to apply force to a small piston and to create a mechanical advantage when the constant pressure is redirected through the pipes on a bigger area, producing high force.the present invention is achieved by the following technical solution: a steel for hydraulic breaker hammer piston, which is a high alloy steel SNCM26VMOD, whose chemical composition is measured by weight percentage mainly including: C=0.14-0.25%, Si= 0.15-0.35%, Mn=0.80-1.20%, Ni=3.25-3.65%, Cr=1.40-1.80%, Mo=0.40-0.60%, V=0.05-0.15%, S≤0.025%, P≤0.025%, The rest are Fe and inevitable impurity elements.The manufacturing process of the steel for hydraulic breaker hammer piston as described above, the whole process steps include electric arc furnace smelting, LF refining, VD refining, electroslag remelting, forging and post-forging heat treatment.1) EAF smelting: the electric arc furnace is used to refine the raw material into molten steel, the molten steel is oxidized and then tapped, and pre-deoxidation and partial alloying are carried out in the ladle;

 2) LF refining: LF refining process uses calcium carbide and carbon powder for diffusion deoxidation, white slag retention time ≥ 25 minutes;3) VD refining: Before the VD refining, the chemical composition is adjusted according to the internal control target value. Under the vacuum degree of 67Pa, the vacuum is kept for ≥30 minutes, and the weak agitation time of the bottom of the ladle is ≥15 minutes. After the steel is sedated, argon is used. Gas protection casting;4) Electroslag remelting: After the steel ingot obtained by the electric arc furnace smelting, LF refining and VD refining process steps is demolded, the hot slag is remelted, and the electroslag ingot obtained after electroslag remelting is demolded and then cooled to 450. ~500 ° C cover cold;5) Forging: The electroslag ingot is heated in a vehicle-type gas furnace. The heating furnace temperature is 1230±20°C, the holding time is 2~4h, the initial forging temperature is 1180～900°C, the final forging temperature is ≥800°C, and the hydraulic press is adopted. Wrong protection plate, then upset to H = ϕ600 ~ ϕ700mm, on the upper and lower flat anvil to lengthen to the hot side 400mm, the amount of reduction 20% ~ 30%, then pour the eight sides to the hot side 420mm, pour the eight squares back to the furnace insulation 2-4h, the furnace temperature is between 1180 ~ 850 °C, and the furnace is forged by 1800T precision forging machine. The deformation amount of the hammer weight control is 80-100mm per pass.6) Post-forging heat treatment: After-forging heat treatment includes normalizing and annealing process, after forging, air cooling to 280-320 ° C, heat preservation 2 ~ 3.5h / 100mm, and then heating to 900 ~ 940 ° C at ≤ 80 ° C / h speed , heat preservation 1 ~ 1.5h / 100mm, and then air-cooled to 280 ~ 320 ° C, the furnace insulation 2 ~ 3.5h / 100mm, the insulation is raised to 650 ~ 700 ° C after the insulation is slowly cooled, the holding time is 6 ~8h/100mm.