Analysis of Manufacturing Bimetallic Tubes by the Cold Drawing Process

Abstract

Drawing processes apply to obtain the bimetallic tubes from the different metals and alloys, combined in the solid state, which significantly affects the specificity of this process. The manufacturing of bimetallic tubes by drawing process depends on many factors which include: preparation of the surface of materials joined in the solid state, the geometric parameters of the working tool, technological parameters of the drawing process (drawing speed, type of lubricant, the use of back pull etc.). Generally, the cold drawing process of producing the bimetallic tubes refers to metals which have high ductility (copper, aluminum, etc.). The tube sinking (tube drawing without a mandrel) of bimetallic tubes together with joining them at the interface of the two metal in the solid-state is applied for tubes of the diameter range between 6 to 20 mm and based on of the reducing the diameter of the tube. However, a slight increase of wall thickness ca. 0.05 ÷ 0.10 mm can appear, which is not dangerous phenomenon in case of producing the bimetallic tubes by joining in the solid-state. The aim of the research was to investigate the technology of tubes drawing process from non-ferrous metal, drawing process of bimetallic tubes and the production of bimetallic tubes in layers composition: cooper Cu-ETP - brass CuZn37 and CuZn37 brass - copper Cu-ETP in the tube sinking process. The research program included: production of bimetallic tubes with a different composition (Cu- ETP-CuZn37 and CuZn37-Cu-ETP) and a different percentage of the cross-section components; analysis of changes of tube wall thickness and the layer composition of the bimetallic tube, based on measurements on the workshop microscope; analysis of the material flow in the process of the bimetallic tubes production based on the measurements results of a profilograph CP-200.

Deformation Behavior Causing Excessive Thinning of Outer Diameter of Micro Metal Tubes in Hollow Sinking

“…The experimental values of the total strain εtotal, the bulk elastic modulus E, and the apparent elastic modulus E' are substituted into Equation (15). The plastic strain obtained by Equation ( 15) generally agrees with the value obtained from Equation (9). Therefore, the unloading behavior can be expressed by a quadratic approximation.…”

“…In this study, tubes with a maximum outer diameter of 2 mm, which are required for several applications [5], were defined as the microscale tubes. Generally, the outer diameter of a macroscale drawn tube, such as an outer diameter of about 20 mm, matches the die diameter [9]. However, the authors reported that the outer diameter of the microscale drawn tubes with the outer diameter of about 1.5 mm became smaller than the die diameter starting from the die approach end [10].…”

Analysis of the forming characteristics for Cu/Al bimetal tubes produced by the spinning process

“…Based on increasing demand to improve performance while reducing weight, the use of bimetal tubing is becoming more widely used in the aerospace, nuclear energy, and automotive and petrochemical industries. At the present time, bimetal tubes are mainly produced and fabricated using processes which includes hydraulic bulging [1], hot extrusion [2], hot rolling [3], mechanical drawing [4], explosive welding [5], as well as other plastic forming techniques by centrifugal casting methods [6], electromagnetic forming method [7], etc. Yet the above forming methods have some problems such as complex structure and low flexibility of the tooling.…”