Process for forming hollow member with complicated cross-section
AssigneeHarbin Institute of Technology, Weihai
InventorsGuannan CHU, Yanli LIN, Shijian YUAN
Life of this patent
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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.
Claims4
A process for forming a hollow member with complicated cross-section, the process comprising steps of:
- (1) analyzing cross-sectional perimeters of the member to find the shortest and the longest ones, wherein, the cross-section with the shortest perimeter is designated as a cross-section A and the cross-section with the longest one is designated as a cross-section B;
- (2) selecting a tube blank, the cross-sectional perimeter, designated as “L”, of which should not be longer than that of the cross-section B of the member;
- (3) designing a die C, a die D and two seal punches in accordance with the shape of the member 1, which is the same as the prior art and thus is not described in detail herein;
- (4) placing the tube blank into the die D, after which ends of the tube blank are sealed by the seal punches and the inside of the tube blank is filled with a fluid medium;
- (5) moving the die C towards the die D such that the die C begins to be in contact with the tube blank;
- (6) adjusting internal pressure of the tube blank to p1;
- (7) continuing moving the die C towards the die D, a bending moment M thereby generated at the tube blank by the combined action of forces from the dies and the internal pressure, wherein, the bending moment M enables cross-sections of the tube blank to undergo bending deformation and be gradually in close contact with inner surfaces of the dies C and D;
- (8) adjusting the internal pressure of the tube blank to p2 when the tube blank at the cross-section A is in close contact with 80%-100% of the inner surfaces of the dies C and D;
- wherein, p2 should be higher than a pressure for suppressing wrinkling required by the forming process, but lower than a pressure for reshaping the tube blank, and calculation methods for the two pressures are the same as the prior art and thus are not described in detail herein;
- (9) continuing moving the die C towards the die D until the tube blank at the cross-section B is in close contact with complete inner surfaces of the dies C and D;
- wherein, during this process, side walls (LL and RR) of the tube blank undergo compressive deformation under the support of the internal pressure p2 of the tube blank at the cross-section A;
- and the tube blank at the other cross-sections first undergoes bending deformation under the combined action of forces from the dies and the internal pressure and then compressive deformation as lowering the upper die after the tube blank is in contact with 80%-100% of the inner surfaces of the dies;
- (10) removing the seal punch to unseal the tube blank;
- (11) withdrawing the die C such that the formed member can be removed;
- and
- (12) removing the formed member and then clearing off the fluid medium inside.
Dependencies are inferred from the claim text.