Method for making an extruder sleeve

A method of making a bimetallic extruder sleeve, comprising the following steps:

• (a) preparing two bimetallic tubes, each tube having substantially the same dimensions;
• and also preparing a rear sleeve part, and a front sleeve part;
• (b) fixing each tube with a plurality of clamping blocks having openings on one side;
• (c) adjusting each of the clamped tubes on a standard level bench, and then fastening said plurality of clamping blocks to the bench with each tube clamped tightly in the clamping blocks;
• (d) inserting two inner support tools in each of the tubes at each end thereof for supporting the inner surface of each of the tubes against external forces;
• (e) moving each clamped bimetal tube to a thread cut machine, adjusting the spindle of the thread cut machine to move parallel to the openings on one side of the clamping blocks, and then cutting each clamped tube to form a tube of C-shaped cross section;
• (f) grinding the surfaces cut on said tubes of C-shaped cross section to a desired roughness in a plane parallel to surfaces at the openings of the clamping blocks;
• (g) detaching said tubes of C-shaped cross section from said plurality of clamping blocks and removing said inner support tools, and clamping said two tubes of C-shaped cross section together with two fixtures having an 8-shaped cross section;
• (h) applying spot welding at junctions of said two tubes of C-shaped cross section for 6-8 spots to form an 8-shaped bushing, and then detaching said two fixtures of 8-shaped cross section;
• (i) removing projections on the 8-shaped bushing caused by the spot welding;
• (j) heating the rear sleeve part in a heating furnace for 3-5 hours to reach a temperature of 300-400° C. and a thermal expansion of 0.3-0.5 mm, and then inserting the 8-shaped bushing into the expanded rear sleeve part;
• and
• (k) fastening the front sleeve part to the rear sleeve part.