Views: 226 Author: Kaylee Publish Time: 2024-04-15 Origin: Site
Stainless steel seamless pipe is a kind of hollow section, no joints around the strip of steel, stainless steel seamless pipe characteristics:
First, the thicker the wall thickness of the product, the more economical and practical it is, the thinner the wall thickness, its processing costs will rise significantly
Second, the process of the product determines its limited performance, the general seamless steel pipe precision is low, the wall thickness is uneven, the external brightness of the tube is low, the measurement cost is high, and the internal surface has pitting and black spots are not easy to remove
Third, its detection and shaping must be processed offline. Therefore, it embodies its superiority in high pressure, high strength and mechanical structure materials.
According to the rolling method, the stainless steel pipe is divided into hot rolling, hot extrusion and cold drawing (rolling).
According to the different metallographic structure of stainless steel, it is divided into half ferritic half martensitic stainless steel seamless pipe, martensitic stainless steel seamless pipe, austenitic stainless steel seamless pipe, and austenitic ferritic stainless steel seamless pipe.
1. Hot rolling (extruded seamless steel pipe): round tube billet → heating → perforation → three-roll skew rolling, continuous rolling or extrusion → Stripping → sizing (or reducing) → cooling → straightening → hydraulic test (or detection) → marking → storage
The raw material of the rolling seamless tube is a round tube blank, the round tube embryo is cut by the cutting machine and the growth of the billet is about 1 meter, and is sent to the furnace by the conveyor belt for heating, the billet is sent to the furnace for heating, the temperature is about 1200 degrees Celsius, and the fuel is hydrogen or acetylene. The temperature control in the furnace is the key problem. After the round tube billet is released, it must be perforated by the pressure piercing machine. Generally, the most common piercing machine is the conical roll piercing machine, which has high production efficiency, good product quality, large perforating and expanding diameter, and can wear a variety of steel. After the perforation, the round tube blank is successively rolled by three roller skew, continuous rolling or extrusion. After extrusion, the pipe is removed for sizing, and the sizing machine rotates into the steel embryo at high speed through the conical drill to punch holes and form the steel pipe. The inner diameter of the steel pipe is determined by the outer diameter length of the caliper drill bit. After the steel pipe is calibrated, it enters the cooling tower and is cooled by water spray. After the steel pipe is cooled, it will be straightened. The steel pipe is straightened
It is sent by conveyor belt to metal flaw detector (or hydraulic test) for internal flaw detection. If there are cracks, bubbles and other problems inside the steel pipe, it will be detected. After the steel pipe inspection, it is also strictly selected by hand. After the steel pipe quality inspection, paint the number, specification, production batch number, etc. And hoisted by crane into the warehouse.
2. Cold-drawn (rolled) seamless steel pipe: round tube blank → heating → perforation → heading → annealing → pickling → oiling (copper plating) → multi-pass cold drawing (cold rolling) → billet → Heat treatment → straightening → hydraulic test (inspection) → marking → storage.
The rolling method of cold-drawn (rolled) seamless steel pipe is more complicated than that of hot-rolled (extruded) seamless steel pipe.
The first three steps of their production process are basically the same.
The difference starts from the fourth step, after the round tube blank is punched, it should be headed and annealed.
After annealing, a special acidic liquid is used for pickling. After pickling, apply oil. This is followed by a special heat treatment of the tube after multiple cold drawing (cold rolling).
After heat treatment, it is straightened. After the steel pipe is straightened, it is sent to the metal inspection machine (or hydraulic test) for internal inspection. If there are cracks, bubbles and other problems inside the steel pipe, it will be detected.
After the steel pipe inspection, it is also strictly selected by hand.
After the steel pipe quality inspection, paint the number, specification, production batch number, etc. And hoisted by crane into the warehouse.
1, according to different production methods can be divided into hot rolled pipe, cold rolled pipe, cold drawn pipe, extrusion pipe, etc.
1.1, hot rolled seamless pipe is generally produced on the automatic tube rolling unit. After checking and removing the surface defects, the solid tube blank is cut into the required length, centered on the perforated end face of the tube blank, and then sent to the heating furnace for heating, and perforated on the perforating machine. In the perforation at the same time continuously rotating and advancing, under the action of the roll and the head, the inside of the tube blank gradually formed a cavity, called the capillary. It is then sent to the automatic tube mill to continue rolling. Finally, the wall thickness of the whole machine is adjusted, and the diameter is determined by the sizing machine to meet the specification requirements. It is an advanced method to produce hot-rolled seamless steel pipe with continuous tube rolling unit.
1.2, if you want to obtain a smaller size and better quality seamless pipe, you must use cold rolling, cold drawing or a combination of the two methods. Cold rolling is usually carried out on a two-high mill, in which steel pipes are rolled in a ring pass consisting of a variable circular groove and a stationary conical head. Cold drawing is usually carried out on a single or double chain cold drawing machine of 0.5 ~ 100T. 1.3. The extrusion method is to place the heated tube blank in a closed extrusion circle, and the perforating rod moves with the extrusion rod to make the extrusion part extruded from the smaller die hole. This method can produce steel pipes with smaller diameters.
