The key technology of cast iron ground rails lies in the trimming of the pouring cupIn the pouring cup stage of the cast iron ground rail, the pouring cup needs to be placed on the placement rack, the excess floating sand at the mouth and bottom of the pouring cup is polished with an abrasive cloth or grinding wheel fragment, and the floating sand is blown clean with compressed air. At the same time, the filter screen and inoculation block should be placed in the pouring cup, and the filter screen should be correctly placed according to the specifications and models, and the residue in the filter screen should be blown clean with compressed air before placement. After the cast iron rail closes, the iron mold needs to be transferred to the sand coating process of the pouring cup, and the mud ring needs to be squeezed at the upper part of the cast iron rail iron mold more than 3mm away from the gate hole edge, and the mud ring needs to be kept continuous.
Because of its simplicity, economy and ability to ensure measurement accuracy, the cast iron ground rail detection method has been widely used in the detection of cast iron ground rail. This method uses the cast iron ground rail as the workbench, and measures the measured specimen according to the measuring tools, table frames and other auxiliary tools such as the workpiece, small square iron, square box, cylindrical angle ruler. This method makes full use of the characteristics of the equal radius of the cylinder and the steel ball in all directions, as well as the characteristics of the radius at the contact point and the perpendicular contact surface, and the cylinder and the steel ball are leaned against the measured surface to achieve the purpose of changing the measurement box. In addition, the cast iron ground rail is also fully used as a reference plane, and the height value of each different point, line and face plane of the test piece can be measured from any position.
The cutting process of cast iron ground rail is to shape and cut the wool plate or polished plate according to the length and width of the order requirements to obtain the required specification plate. This process is commonly used to complete the cutting machine, double saw blade cutting machine, transverse cutting machine, bridge cutting machine, cantilever cutting machine, hand cutting machine and other equipment. In addition, according to the specific needs of cast iron ground rail decoration, auxiliary processing such as edging, chamfering, opening holes, drilling, and milling lace is often carried out. These processes are often completed by automatic edge grinding and chamfering machines, special copy milling machines for stone, thin-wall drilling machines, hand-held diamond circular saws, hand-held grinding and polishing machines, and other equipment.
Cast iron ground rail plates inevitably have cracks and holes, and problems such as fractures, scratches, and edge bumps are often produced during the processing process. These problems can be repaired by cleaning the inspection library, and if the problem is not serious, it can be bonded and repaired to reduce the scrap rate. This process is usually carried out manually, and some imported production uses automatic continuous repair machines for repair, and the color of the repair should be basically the same. Commonly used methods such as automatic continuous repair machine, blowing and air dryer or manual inspection and manual repair can also be used for the repair of cast iron ground rails.
Before adjusting the cast iron ground rail, check whether each fulcrum is solid to avoid the fulcrum being suspended. Use a straight ruler to place the plate diagonally and gently shake one end to observe whether the support point of the ruler touching the cast iron ground rail is about 2 9 of the ruler. By analogy, the same method is used to detect the 4 corners of the cast iron ground rail. If there are more than 3 fulcrums, the auxiliary fulcrum can also be adjusted in the same way, but it should be noted that the strength of the auxiliary fulcrum is smaller than that of the 4 cast iron ground rail angles. The cast iron ground rail adjusted in this way will be very smooth, which is convenient for subsequent inspection.
For ductile castings and ductile iron parts, commonly used heat treatment methods include low-temperature graphitization annealing and high-temperature graphitization annealing. The heating temperature of low-temperature graphitization annealing is 720 760, and the furnace is cooled to below 500 and air-cooled, so that the cast iron ground rail eutectic cementite is decomposed to obtain ductile iron with ferrite matrix to improve toughness. The heating temperature of high-temperature graphitization annealing is 880 930, which is turned to 720 760 for heat preservation, and cooled with the furnace to below 500 for air cooling.