Free forging productivity is low, the processing margin is large, but the tool is simple, versatile, it is widely used for forging shape simple single piece, small batch production forging. Free forging equipment with air hammer, steam - air hammer and hydraulic press, respectively, suitable for small, medium and large forging production. Die forging high productivity, simple operation, easy to achieve mechanization and automation. Die forging size accuracy, mechanical processing margin is small, forging the fiber structure distribution is more reasonable, can further improve the service life of parts. Free forging the basic process: free forging, the shape of the forging is through some basic deformation process will gradually forging the blank. The basic processes of free forging are upsetting, drawing, punching, bending and cutting.

First of all to the technical mold layout design should be reasonable, the thickness is not too disparate, the shape should be symmetrical, on the deformation of the larger mold to grasp the deformation rules, reserved processing margin, on the large, fine messy mold optional combination layout. For some fine messy mold can be used pre-heat treatment, aging heat treatment, quenching and tempering nitriding heat treatment to control the accuracy of the mold. In the repair mold sand eyes, stomata, wear and other shortcomings, the choice of cold welding machine and other small heat affected repair equipment to avoid the deformation occurred during the repair process. Fine miscellaneous molds should be preheated to eliminate the residual stresses that occur during machining. On the fine messy mold, in the case of conditions agreed, try to use vacuum heating quenching and quenching after the cryogenic treatment. In the premise of the hardness of the tube, try to use pre-cooling, grading cooling quenching or quenching process. Reasonable selection of materials. Fine molds should be selected for the micro-deformation of the mold material, carbide segregation of the mold steel should be a reasonable casting and tempering heat treatment, the larger and can not cast mold steel can be solid solution double fine heat treatment. Reasonable selection of heating temperature, control of heating speed, on the fine messy mold can be used to slow heating, preheating and other balanced heating method to reduce the mold heat treatment deformation.

In recent years, at home and abroad gradually attach importance to the integrity of seamless pipe management concept, developed the relevant standards and norms. The probability of the fracture produced by the straight seam welded pipe is the main need to pay attention to, the seam welded pipe fracture, hydraulic parts in the design of the use of mechanical properties, brittle fracture and the use of components related to the temperature. Through the study found that when the temperature is lower than a certain temperature value, the metal material will gradually change into a brittle state, the impact absorption power decreased significantly, this phenomenon known as cold brittle, this situation is likely to cause straight seam welded pipe production fracture, affecting production and processing. Therefore, the design should also be based on the work of the component temperature to select the appropriate cold brittle transition temperature of the material. In general, it is assumed that the material is evenly considered safe design, and sometimes accidental fracture accidents occur. As the hot-rolled tube billet cracks or other defects or high-precision cold-drawn tube was made after the cylinder, straight seam steel pipe when cold. The use of the process of the fracture occurred, almost no plastic deformation occurs, are generally brittle fracture.

(1) Guide roller The role of the guide roller is to control the direction of the weld to ensure that the pipe straight does not reverse into the squeeze roller, the second is to ease the edge of the extension and rebound to determine the size of the opening angle. Adjustment is not easy to cause steel pipe seam twisting or welding, steel pipe edge waves and other defects. (2) Squeeze rollers The role of the squeeze roller is the edge of the heating wire welding temperature of the body under the action of the pressure to complete the welding. In the process of production, we should pay attention to the size of the opening angle of the squeeze roller. When the pressing force is small, the strength of the weld metal will decrease and the crack will be cracked. When the pressing force is large, the strength of the weld will be reduced, Resulting in welding and other welding defects.

The quality of the advanced pipe is largely dependent on the development of nondestructive testing techniques. The use of non-destructive testing, on the one hand can check the defects of the pipe to ensure the reliability of the use of welded pipe; on the other hand can also test the results of the information feedback system, the pipe production process quality control. Therefore, the development of non-destructive testing is to improve the quality of welding pipe and the level of production of important technical measures. In order to achieve the above objectives, countries attach great importance to the production of new welding pipe technology and new technology experimental research. Such as the United States recently developed a new wave of square wave welding technology to produce 7-76 mm diameter pipe. As the square wave welding does not have the effect of current peak, so the edge of the heating uniform, good weld quality. Production of thin-walled and thin-walled pipe roll forming technology, is now available for many countries. Weld pipe and cold drawing and cold rolling to achieve continuous production, has also achieved good results. The United States is also in a set of 406 mm six-seam welded pipe unit, the configuration of the cold expansion machine to improve the strength of finished pipe (about 25%), while improving the pipe section shape and dimensional accuracy.