Abstract: A preforming method for a high-strength steel variable-diameter tubular part is provided, which belongs to the technical field of metal forming process. The preforming method for a high-strength steel variable-diameter tubular part includes: selecting a tubular blank; and preparing a tubular blank forming mold, where the tubular blank forming mold includes a preforming mold and a final forming mold; sealing and pressurizing the tubular blank; heating the tubular blank by using electrodes; preforming the tubular part at a constant temperature; maintaining a temperature T1 and moving the preformed tubular part to the final forming mold;finally forming the tubular part. Through two steps of operation of preforming and final forming, and maintaining a temperature during moving the tubular blank between the two steps, so that the conversion of intrametallic structure between the two steps is improved, and the performance of the tubular part is improved.

Abstract: Disclosed is a mold for partially shortening the circumference of a tube billet and a using method of the mold. The mold comprises an upper mold, a lower mold and a mold core used for being inserted into a tube cavity of the tube billet, wherein the upper mold is provided with an upper mold cavity, the lower mold is provided with a lower mold cavity, and the upper mold cavity and the lower mold cavity are matched to form a mold cavity. After the mold core is placed in the mold cavity, a tube billet deformation cavity is formed in the mold cavity; and the upper mold cavity and/or the lower mold cavity are/is in the shape of a flaring, the two sides of the flaring are arc-shaped, and included angles are formed between the two sides of the flaring and the moving direction of a movable mold.

Abstract: A method for manufacturing a hollow camshaft is provided, and more particularly, a method for manufacturing a combined hollow camshaft by an axial-compression upsetting-deformation technique. The present method solves a problem that the current camshaft manufactured in an internal high-pressure expansion manner in the prior art has the insufficient locking force to cause the loosening of a cam. The method is as follows: a camshaft is formed by combining two independent units, namely a cam and a shaft tube. Non-circular countersinks are distributed on two sides of the cam. Thrust steps are formed on the shaft tube correspondingly. The cam is placed between the two thrust steps of the shaft tube. The locking force is applied to the cam by utilizing the thrust steps on the two sides of the cam based on thermal expansion and contraction. Simultaneously, the thrust steps lock the cam with the countersinks.

Abstract: A method for manufacturing a hollow camshaft is provided, and more particularly, a method for manufacturing a combined hollow camshaft by an axial-compression upsetting-deformation technique. The present method solves a problem that the current camshaft manufactured in an internal high-pressure expansion manner in the prior art has the insufficient locking force to cause the loosening of a cam. The method is as follows: a camshaft is formed by combining two independent units, namely a cam and a shaft tube. Non-circular countersinks are distributed on two sides of the cam. Thrust steps are formed on the shaft tube correspondingly. The cam is placed between the two thrust steps of the shaft tube. The locking force is applied to the cam by utilizing the thrust steps on the two sides of the cam based on thermal expansion and contraction. Simultaneously, the thrust steps lock the cam with the countersinks.

Abstract: A process for forming a hollow member with A complicated cross-section wherein a section of a tube blank first undergoes a bending deformation due to its internal pressure and bend moment generated by the upsetting of an upper die, and is then compressed to be molded under the support of the internal pressure. The process of the invention does not require the reshaping step at an increased pressure. The process can make a hollow member with a complicated cross-section formed under a low pressure, and solves a technical bottleneck relating to a conventional process for forming this kind of members that is subject to an ultrahigh pressure generator.

Abstract: A process for forming a hollow member with A complicated cross-section wherein a section of a tube blank first undergoes a bending deformation due to its internal pressure and bend moment generated by the upsetting of an upper die, and is then compressed to be molded under the support of the internal pressure. The process of the invention does not require the reshaping step at an increased pressure. The process can make a hollow member with a complicated cross-section formed under a low pressure, and solves a technical bottleneck relating to a conventional process for forming this kind of members that is subject to an ultrahigh pressure generator.