Production process analysis of stainless steel seamless steel pipe
Simplify the main production process:
Round steel → re-inspection → peeling → blanking → centering → heating → perforation → pickling → flat head → inspection and grinding → cold rolling (cold drawing) → degreasing → heat treatment → straightening → pipe cutting (cut to length) → pickling /passivation→finished product inspection (eddy current, ultrasonic, water pressure)→packaging and storage.
1. Round bar cutting: After receiving the round bar from the raw material warehouse, calculate the cutting length of the round bar according to the requirements of the process, and draw a line on the round bar. After the bow sawing machine is started, the grinding wheel is cut along the segment line, and the cut circle The steel is stacked separately according to the steel type, furnace number, production batch number and specification, and the ends are distinguished by different colors of paint.
2. Centering: When centering the cross-arm drilling machine, first find the center point on a section of the round steel, drill a sample hole, and then vertically fix it on the drilling machine table for centering. The centered round steel is stacked separately according to the steel type, furnace number, specification and production batch number.
3. Peeling: Peeling is carried out after the incoming material has passed the inspection. Peeling includes lathe peeling and whirlwind cutting. Lathe lathe peeling is performed on the lathe with a processing method of one clip and one top. Whirlwind cutting is to hang the round steel on the machine tool Perform whirl cutting.
4. Surface inspection: The quality inspection of the light round steel after peeling is carried out, and the existing surface defects are marked, and the grinding personnel will grind until it is qualified. The round steel that has passed the inspection is stacked separately according to steel type, furnace number, specification and production batch number.
5. Round steel heating: The round steel heating equipment includes a gas-type inclined bottom furnace and a gas-type box-type furnace. The gas-fired inclined-bottom furnace is used for heating when a large batch of incoming materials is supplied, and the gas-fired box-type furnace is used for heating when a small batch of incoming materials is supplied. When entering the furnace, the round steel of different steel types, furnace numbers, and specifications is separated by the old outer film. When the round steel is heated, the steel turner uses special tools to turn the steel to ensure that the round steel is heated evenly.
6. Hot rolling piercing: use piercing unit and air compressor. According to the specifications of the perforated round steel, select the corresponding guide plate and molybdenum plug, use the piercer to perforate the heated round steel, and the pierced waste pipe is randomly put into the water pool for full cooling.
7. Inspection and grinding: Inspect the inner and outer surfaces of the waste pipe to be smooth and flat, and there must be no skins, cracks, interlayers, deep pits, serious thread marks, tower iron, fried sticks, Baotou and sickle heads. The surface defects of waste tubes can be eliminated by local grinding. The waste pipes that have passed the inspection or the waste pipes that have passed the inspection after minor defects have been repaired are bound by the binding workers in the workshop according to the requirements, and stacked separately according to the steel type, furnace number, specification, and production batch number of the waste pipes.
8. Straightening: The raw material pipes from the piercing workshop are packed in bundles. The shape of the incoming raw pipe is bent and needs to be straightened. The equipment used for straightening is vertical straightening machine, horizontal straightening machine and vertical hydraulic press (used for pre-straightening when the bending degree of the steel pipe is large). In order to prevent the steel pipe from bouncing during straightening, a nylon sleeve is used to limit the steel pipe.
9. Pipe cutting: According to the production plan, the straightened raw pipe needs to be cut head and tail, and the equipment used is a grinding wheel cutting machine.
10. Pickling: The straightened steel pipe needs to be pickled to remove the scale and impurities on the surface of the waste pipe. Pickling of steel pipes is carried out in the pickling workshop, and the steel pipes are slowly hoisted into the pickling tank for pickling by a crane.
11. Grinding, endoscopic inspection and internal polishing: pickling qualified steel pipes enter the external surface grinding process, and the steel pipes after grinding are subjected to endoscopic inspection, and internal polishing is required for unqualified products or processes with special requirements deal with.
12. Cold rolling process/cold drawing process
Cold rolling: the steel pipe is rolled by the rolls of the cold rolling mill, and the size and length of the steel pipe are changed by continuous cold deformation. The cold rolled steel pipe has a fast forming speed, a large amount of deformation, and a high output.
Cold drawing: use a cold drawing machine to expand and reduce the wall of the steel pipe without heating to change the size and length of the steel pipe. The cold drawn steel pipe has high dimensional accuracy and good surface finish. The disadvantage is that the residual stress is large, and Large-diameter cold-drawn pipes have more times, and the finished product forming speed is slow. The specific process of cold drawing includes:
① Heading and welding head: Before cold drawing, one end of the steel pipe needs to be headed (small-diameter steel pipe) or welded (large-diameter steel pipe) to prepare for the drawing process. A small amount of special specification steel pipe needs to be heated before it is headed.
② Lubrication and baking: Before cold drawing of the steel pipe after head (welding head), the inner hole and outer surface of the steel pipe need to be lubricated, and the steel pipe coated with lubricant must be dried before cold drawing.
③ Cold drawing: The steel pipe after the lubricant is dried enters the cold drawing process, and the equipment used for cold drawing is a chain cold drawing machine and a hydraulic cold drawing machine.
13. Degreasing: The purpose of degreasing is to remove the rolling mill oil attached to the inner wall and outer surface of the steel pipe after rolling by rinsing, so as to avoid polluting the steel surface during annealing and preventing carburization.
14. Heat treatment: Heat treatment restores the shape of the material through recrystallization and reduces the deformation resistance of the metal. The heat treatment equipment is natural gas solid solution heat treatment furnace.
15. Pickling of finished products: The steel pipes after cutting are pickled for finished products, the purpose of which is to passivate the surface, so that a layer of oxidation protection film is formed on the surface of the steel pipes, and the corrosion resistance of the steel pipes is enhanced.
16. Finished product inspection: The process of finished product inspection and test is mainly surface inspection → eddy inspection → super inspection → water pressure → air pressure inspection. Surface inspection is mainly to manually check whether there is any defect on the surface of the steel pipe, whether the length of the steel pipe and the size of the outer wall are qualified; 1. Air pressure is to use hydraulic press and air pressure machine to detect whether the steel pipe is leaking or air leaking, so as to ensure that the steel pipe is intact.
17. Packing and warehousing: The steel pipes that pass the inspection enter the finished product packaging area for packaging. The materials used for packaging include perforated caps, plastic bags, snakeskin cloth, wooden boards, stainless steel belts, etc. The outer surfaces of both ends of the wrapped steel pipe are lined with small wooden boards, and the outer surfaces are fastened with stainless steel belts to prevent contact between steel pipes during transportation and cause collisions. The packed steel pipes enter the finished product stacking area.
