Multi-chamber furnace for vacuum carburizing and quenching of gears, shafts, rings and similar components has at least two process chambers connected in parallel, with a continuous feeding mechanism for individual workpieces. Those chambersthe first one being a heating chamber, the second being a carburizing chamber and the third one diffusion chamberare configured in a vertical arrangement, placed in a shared vacuum space with gas-tight division, whereas at the ends of each chamber there are incorporated heating chambers with thermal insulation, with a graphite heating system and stepping feeding mechanism incorporated in the core for the purpose of continuous feeding of individual workpieces. At the ends of those chambers the construction incorporates transport chambers featuring loading and unloading systems X-Y enabling cooperation with individual process chambers through thermal and gas-tight doors installed in chamber ends, while external access to the transport chambers is ensured through loading and unloading locks.

Disclosed are a steel for a high-temperature carburized gear shaft and a manufacturing method for the steel. The steel for the high-temperature carburized gear shaft comprises the following chemical components in percentage by mass: 0.17-0.22% of C, 0.05-0.35% of Si, 0.80-1.40% of Mn, 0.010-0.035% of S, 0.80-1.40% of Cr, 0.020-0.046% of Al, 0.006-0.020% of N, 0.002-0.030% of Nb, V0.02%, and Ti0.01%. Also disclosed is a manufacturing method for the steel for the high-temperature carburized gear shaft, comprising the steps of: smelting and casting; heating; forging or rolling; and finishing. By reasonably controlling chemical element compositions of the steel, the steel for the gear shaft in the present invention can maintain proper austenite grain size and stability at high temperature, maintains 5-8 grades of the austenite grain size before and after the high-temperature vacuum carburizing at 940-1050 C., can be effectively applied to high-end parts such as a gearbox for a vehicle or a speed reducer and a differential of a new energy vehicle, and has good application prospects and value.

Disclosed are a steel for a high-temperature carburized gear shaft and a manufacturing method for the steel. The steel for the high-temperature carburized gear shaft comprises the following chemical components in percentage by mass: 0.17-0.22% of C, 0.05-0.35% of Si, 0.80-1.40% of Mn, 0.010-0.035% of S, 0.80-1.40% of Cr, 0.020-0.046% of Al, 0.006-0.020% of N, 0.002-0.030% of Nb, V0.02%, and Ti0.01%. Also disclosed is a manufacturing method for the steel for the high-temperature carburized gear shaft, comprising the steps of: smelting and casting; heating; forging or rolling; and finishing. By reasonably controlling chemical element compositions of the steel, the steel for the gear shaft in the present invention can maintain proper austenite grain size and stability at high temperature, maintains 5-8 grades of the austenite grain size before and after the high-temperature vacuum carburizing at 940-1050 C., can be effectively applied to high-end parts such as a gearbox for a vehicle or a speed reducer and a differential of a new energy vehicle, and has good application prospects and value.

A rolled round steel material contains C: 0.38 to 0.55%, Si: 1.0% or less, Mn: 0.20 to 2.0%, S: 0.005 to 0.10%, Cr: 0.01 to 2.0%, Al: 0.003 to 0.10%, B: 0.0005 to 0.0030%, Ti: 0.047% or less, Cu: 0 to 1.0%, Ni: 0 to 3.0%, Mo: 0 to 0.50%, Nb: 0 to 0.10%, V: 0 to 0.30%, Ca: 0 to 0.005%, and Pb: 0 to 0.30%, a remaining portion being constituted by Fe and an impurities, the impurities containing P in an amount of 0.030% or less and N in an amount of 0.008% or less, and has a chemical composition satisfying [3.4NTi3.4N+0.02]. The microstructure is constituted by ferrite (F), lamellar pearlite (LP), and cementite (C) and microstructural features vary in terms of the lateral, longitudinal and central portions of the steel. This steel material has a high base material toughness and good machinability without performing thermal refining.

A rolled round steel material contains C: 0.38 to 0.55%, Si: 1.0% or less, Mn: 0.20 to 2.0%, S: 0.005 to 0.10%, Cr: 0.01 to 2.0%, Al: 0.003 to 0.10%, B: 0.0005 to 0.0030%, Ti: 0.047% or less, Cu: 0 to 1.0%, Ni: 0 to 3.0%, Mo: 0 to 0.50%, Nb: 0 to 0.10%, V: 0 to 0.30%, Ca: 0 to 0.005%, and Pb: 0 to 0.30%, a remaining portion being constituted by Fe and an impurities, the impurities containing P in an amount of 0.030% or less and N in an amount of 0.008% or less, and has a chemical composition satisfying [3.4NTi3.4N+0.02]. The microstructure is constituted by ferrite (F), lamellar pearlite (LP), and cementite (C) and microstructural features vary in terms of the lateral, longitudinal and central portions of the steel. This steel material has a high base material toughness and good machinability without performing thermal refining.

A processing apparatus includes a cutting tool that processes a clamped workpiece, a quenching unit capable of emitting a laser beam, and a vibration cutting unit capable of vibrating a distal end with a vibration cutting tool mounted thereon. The cutting tool, the quenching unit, and the vibration cutting unit are movable relative to the workpiece. The cutting tool cuts the workpiece before being quenched. The quenching unit applies laser quenching as a surface hardening treatment to the workpiece. The vibration cutting unit finishes the quenched workpiece by applying the vibration cutting tool to the workpiece while vibrating the vibration cutting tool.

A method of hardening a planetary gear shaft includes carbonitriding an outer peripheral surface of the planetary gear shaft and quenching the planetary gear shaft in oil at a temperature between approximately 120 and 150 C. The method also includes quenching the planetary gear shaft in a liquid at a temperature between approximately 70 and 120 C., and tempering the planetary gear shaft. After tempering, the outer peripheral surface of the planetary gear shaft includes a surface hardness of HV 832 or more and with the shaft material maintaining a hardness of at least HV 513 to a depth of at least 0.5 mm. High temperature tempering and induction hardening steps may be added to obtain soft ends of the shaft suitable for a staking operation.

A method of hardening a planetary gear shaft includes carbonitriding an outer peripheral surface of the planetary gear shaft and quenching the planetary gear shaft in oil at a temperature between approximately 120 and 150 C. The method also includes quenching the planetary gear shaft in a liquid at a temperature between approximately 70 and 120 C., and tempering the planetary gear shaft. After tempering, the outer peripheral surface of the planetary gear shaft includes a surface hardness of HV 832 or more and with the shaft material maintaining a hardness of at least HV 513 to a depth of at least 0.5 mm. High temperature tempering and induction hardening steps may be added to obtain soft ends of the shaft suitable for a staking operation.

A method for repairing break of a universal connecting rod of a universal coupling includes steps of: cleaning and detecting cracks, providing primary anneal, depositing alloys, providing secondary anneal, manually milling and controlling a quality; wherein depositing the alloys includes forming gradient in an order of a bonding layer, a transition layer, a working layer and a processing layer; wherein the bonding layer: S and P in the depositing area are diluted with an FGM-KM1.sup.# material, for removing or reducing the S and P, so as to avoid cold and hot cracks; the transition layer: which is formed by an FGM-KM2.sup.# material for improving impact toughness and evacuation stress, and appropriate increasing hardness; the working layer: which is formed by an FGM-KM3.sup.# material for improving heat resistance, wear resistance and load capacity; and the processing layer: an FGM-KM4.sup.# material is used to reduce surface hardness and improve processing performance.

A method for repairing break of a universal connecting rod of a universal coupling includes steps of: cleaning and detecting cracks, providing primary anneal, depositing alloys, providing secondary anneal, manually milling and controlling a quality; wherein depositing the alloys includes forming gradient in an order of a bonding layer, a transition layer, a working layer and a processing layer; wherein the bonding layer: S and P in the depositing area are diluted with an FGM-KM1.sup.# material, for removing or reducing the S and P, so as to avoid cold and hot cracks; the transition layer: which is formed by an FGM-KM2.sup.# material for improving impact toughness and evacuation stress, and appropriate increasing hardness; the working layer: which is formed by an FGM-KM3.sup.# material for improving heat resistance, wear resistance and load capacity; and the processing layer: an FGM-KM4.sup.# material is used to reduce surface hardness and improve processing performance.