The production of coupler is divided into two work areas: sand casting and finishing assembly. The main processes of sand mold casting work area include: sand treatment, molding, core making, box closing, smelting, pouring, sand dropping, primary cleaning, pre normalizing, flaw detection, welding repair, quenching and tempering, hardness, etc. The main processes of finishing and assembly work area include: secondary cleaning, finishing, flaw detection, welding repair, tempering, surface quenching, low-temperature tempering, machining, sample passing, re flaw detection, welding wear plate, paint, assembly, three state test, acceptance, product warehousing, etc.
Smelting and pouring. The coupler smelting adopts the double smelting scheme of 10t eccentric electric arc furnace and 20t LF refining furnace. This scheme can significantly reduce the content of harmful elements and gases in steel, improve the morphology and distribution of inclusions, purify molten steel and improve the internal quality of steel castings. The coupler is made of Grade E steel, so molybdenum and other alloys must be added before tapping to refine the grain. The coupler casting line is organically connected with the molding and cleaning processes, and the operation between each process is smooth.
Molding sand and sand treatment. The molding sand of steel castings is made of green molding clay sand and surface back sand, the core sand is made of resin sand, the overall core is made of isocure (triethylamine cured resin sand cold core box) core shooting process, and the manual core is made of self hardening sand resin process; In the sand treatment system, B & p100b-250 roller type sand mixer is used for the surface sand, szg285 rotor sand mixer is used for the back sand, z8480 core shooter is used for the integral core of coupler, Palma automatic continuous sand mixer imported from the United States is used for the manual core sand, Simpson air flow impact regenerator is used for the regeneration of old sand, and the sand treatment system is equipped with on-line detection device.
Modeling and core making. A combined molding line is adopted for the modeling of coupler, which is composed of sand box return line, molding machine and lower core box closing line. The molding machine adopts multi contact vibration molding machine, which has the advantages of simple operation, high production efficiency, uniform compaction rate of molding sand and high surface hardness, and can effectively prevent sand flushing and sand falling of steel castings.
The coupler core making is divided into shooting core and manual core. The whole core of the coupler body and the three inner cavity cores of the coupler tongue (coated sand and z8615 shooting machine) adopt shooting core, and the other small sand cores adopt PEP set self hardening sand and manual core making. The sand core baking line is equipped to bake the resin sand cores such as the whole core to prevent moisture return.
Robot lower core. The overall core of the coupler adopts the robot core, and the other small mud cores are manually core. The robot core adopts the three-dimensional laser scanning identification and positioning system. The appearance and core sand adopt the positioning point method to position, which can effectively ensure the core accuracy and improve the work efficiency. The figure shows the lower core condition of the hook body modeling robot.
One time cleaning and welding repair. One time cleaning includes residual sand removal, pre cutting pouring riser, pre normalizing, shot blasting, pouring riser root cleaning, flaw detection, welding repair, grinding, rough sample passing and other processes. The primary cleaning goal is to clean all sand casting defects of steel castings before quenching and tempering, and the surface quality and overall dimension of steel castings basically meet the requirements. Grade E steel material has poor weldability, easy to crack after welding and is sensitive to ambient temperature. A welding repair heating and insulation furnace is specially set to heat the parts to a certain temperature and keep them warm for a period of time before welding, and keep them warm for a period of time after welding to prevent cracks after welding.
Heat treatment. Heat treatment is divided into five links: pre normalizing, quenching and tempering, post welding tempering, surface quenching and low temperature tempering. Pre normalizing is to improve the as cast structure of steel castings, refine grains, improve the mechanical properties of the body, prevent cracks during welding repair, and prepare for quenching and tempering; The mechanical property index of steel castings shall be adjusted to the required range during quenching and tempering; Tempering after welding, i.e. stress relief tempering after welding repair, with tempering temperature of 500-650 ° C; Surface quenching is mainly carried out at both ends of the pin hole at the tail of the hook body and the ball to improve the surface hardness and wear resistance; The low-temperature tempering temperature is controlled at 190-250 ° C to eliminate the stress caused by local surface quenching and prevent quenching cracks.
Secondary cleaning and finishing. The purpose of secondary cleaning and finishing is to remove the oxide scale generated by quenching and tempering, check and eliminate the cracks generated by quenching and tempering, and carry out finishing, grinding and surface repair of steel castings to make them meet the product technical conditions and relevant standards. For defect repair welding during secondary cleaning, local thermal insulation, overall tempering and re quenching and tempering shall be carried out respectively according to the location, quantity and size of defects.
Flaw detection. The hook body and tongue shall undergo flaw detection at least twice before and after quenching and tempering. If there are cracks, flaw detection shall be carried out after welding repair until there are no cracks. At the same time, flaw detection shall be confirmed again before product assembly to ensure that the internal quality of the coupler assembled and delivered meets the requirements.
Processing and assembly. The coupler tongue needs to be bored to process the pin hole, and the coupler assembly and three state test are completed at the assembly bench.
Inspection and test. The inspection includes the inspection of product raw materials, the real-time monitoring of molding sand process parameters of sand treatment system, the inspection of product chemical composition, mechanical properties, metallographic structure, inclusion morphology, local hardness, etc., and the implementation of assembly clearance, three state action, relevant material test and type test after coupler assembly.