EXPERIMENTAL INVESTIGATION AND NUMERICAL ANALYSIS OF NOVEL PROCESS TO PRODUCE OF HIGH STRENGTH BIMETAL TUBES BY RUBBER PAD TUBE STRAINING (RPTS) METHOD

In this paper, the strain area has been designed as a diamond in a new Rubber Pad Tube Straining (RPTS) method, and the tests are applied to two layer copperaluminum. Tubes used in this experiment are pure copper with dimensions with an outer diameter of 22 mm and a thickness of 0.85 mm and also for the aluminum tube grade 1100 with an outer diameter of 22 mm and a thickness of 1 mm, which, after cutting at a length of 110 mm in diameter, were placed in the die. To get the desired result, it was decided to use high-strength polyurethane. A mandrel, which has a convex portion in the form of a diamond, is pushed into the tube, while the tube is xed by a cylindrical rubber. As a result, the initial diameter of the tube is increased locally, and then, when the mandrel goes down, the energy stored in the rubber returns the tube to its original dimensions. The simulation of the process using the Abaqus nite element software showed that the highest strain is obtained when the maximum diameter of the convex section is as large as the outer diameter of the tube. The strength of the two-layer tube in the third pass was 180/6 MPa, which grew to the same as the aluminum base metal and was lower than that of the copper base metal. The hardness of the copper section of two layer tube under the process compare to its base metal obtained from 92 HV to 130 HV. This condition had a growth for the aluminous layer of 40 HV in the base metal to 50 HV in the two-layer aluminum section. The simulation shows that regardless of the copper-aluminum-metal bonding region, the proposed method has major advantages including high strain homogeneity. The process force is also calculated in the rst pass of about 31 tons.