Metal working – Method of mechanical manufacture – Assembling or joining
Reexamination Certificate
1998-11-24
2001-03-06
Bryant, David P. (Department: 3726)
Metal working
Method of mechanical manufacture
Assembling or joining
C029S463000, C029S466000, C029S557000, C029SDIG001, C029SDIG002, C029SDIG003, C029SDIG004
Reexamination Certificate
active
06195866
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a method of making an extruder sleeve, and, more particularly, to a method for making a dual straight-hole sleeve which has a bimetallic inner bushing and two outer sleeve parts.
2. Description of Related Art
A conventional extruder sleeve with a dual straight-hole design is shown in
FIGS. 1A and 1B
. It is integrally made as a single piece, with an inner surface having a hardened layer of 0.3-0.6 mm treated by nitridation. Because the hardened layer is only 0.3-0.6 mm, it is easily worn out by the extruded plastic material in the extruder. Therefore, conventional extruder sleeves have inadequate wear resistance and low durability.
SUMMARY OF THE INVENTION
The present disclosure is directed to a method of making a dual straight-hole extruder sleeve which includes a front sleeve part, a bimetallic inner bushing, and a rear sleeve part. Briefly, the method proceeds as follows: (1) prepare two bimetallic tubes having the same dimensions, and also prepare a rear sleeve part and a front sleeve part; (2) fix each tube at its outer surface along the longitudinal axis thereof with clamping blocks that are arranged parallel to one another; (3) adjust each clamped tube on a standard level bench, and then fasten the clamping blocks to the bench so that each tube is clamped tightly; (4) insert inner support tools in each tube for supporting the tube against external forces; (5) move each clamped tube to a thread cutting machine and adjust the spindle of the thread cutting machine to move parallel to the openings on one side of the clamping blocks, and then cut the clamped tube longitudinally to form a tube of C-shaped cross section; (6) apply a plane grinder to the rough surfaces cut on each tube of C-shaped cross section in order to achieve desired roughness; (7) detach each ground tube of C-shaped cross section from the clamping blocks and the inner support tools, and clamp the two tubes of C-shaped cross section together in a fixture having an 8-shaped cross section; (8) apply spot welding to join the two tubes of C-shaped cross section and form an 8-shaped hole bushing, and then detach the fixture; (9) remove any projections on the dual inner bushing tube caused by the spot welding process; (10) heat the rear sleeve part in a heating furnace at 300-400° C. for three to five hours in order to thermally expand the rear sleeve part, and then insert the 8-shaped hole bushing into the expanded rear sleeve part; and (11) finally, fasten the front sleeve part to the rear sleeve part.
The extruder sleeve made by the present invention provides higher wear resistance and durability than conventional extruder sleeves.
An object of the present invention is to provide a method for making a bimetallic 8-shaped hole extruder sleeve which has good wear resistance and durability.
REFERENCES:
patent: 3590429 (1971-07-01), Homberg et al.
patent: 3910316 (1975-10-01), Reifenhauser
patent: 3970113 (1976-07-01), Guttinger et al.
patent: 4117583 (1978-10-01), Gnadig et al.
patent: 4590033 (1986-05-01), Chapet
patent: 5110284 (1992-05-01), Dienst et al.
Bacon & Thomas PLLC
Bryant David P.
Nan Ya Plastics Corporation
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