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21: 656–661.[4] L. S. Turng, M. Peic. Computeraided process and designoptimization for injection moulding. IMechE. 2002。. The slide and theponents which are in touch with the slide are easy to wear because the slide moves frequently. In order topostpone wearing the ponents, the two steps are adopted as follow: The slide is made of 718H and is quenched to 50HRC around. The wear plates are laid on the bottom of the slide and on the back of the slide. The wear plates are madeof GS2510 and are quenched to 60HRC around. The slide way is formed by the slide wedge and the core plate. The slide way is easy to machine and to maintain.1. slide 2. fixed block 3. locking block 4. angle pin 5. wearplate 6. positioning screw plate 8. slide wedge 9.spring rodFigure 3. Angle pin corepulling mechanism III. DESIGN OF ANGLE EJECTOR ROD COREPULLINGMECHANISMSFour angle ejector rod corepulling mechanisms are designed in the area of D and E of the plastic part 1 and inthe area of I and J of the plastic part 2. The mechanisms are distributed in figure 4. Distribution of angle ejector rod corepullingmechanismsTaking the angle ejector rod corepulling mechanism 1 shown in figure 4 for example, the mechanism is mostlyposed of angle ejector block 1, angle ejector rod 9, angle ejector guide block 4, angle ejector guide block 6, angle pin 5, angle ejector slide 7 and wear plate 8. The mechanism is shown in figure 51. angle ejector block 2. straight guide bush 3. headed guidebush 4. angle ejector guide block 5. angle pin 6. angleejector guide block 7. angle ejector slide 8. wear plate 9.angle ejector rod 10. pinFigure 5. Angle ejector rod corepulling mechanismThe angle ejector rod is made of SUJ2 which is premium alloy material and the surface is in nitrogen treatment. The wear resistance of the angle ejector rod is well. By analyzing and puting, the Inclined angle of the angle ejector rod is 20176。demouldingI. INTRODUCTIONTwo automobile engine covers are shown in figure plastic parts are in mass production and the two plasticparts are asked to be moulded in one mould. The plastic parts are made of polypropylene (PP). The molding shrinkage is %. The outline dimensions of two plastic parts are and . The basic wall thickness of the two plastic parts is . The appearance of the plastic parts should maintain perfect. The mark of pouring and ejecting is not allowable to appear on the plastic disfigurement of injection such as weld lines, sink mark, flashing, splay, etc. is not allowable to appear either. Design of the parting surface of the two plastic parts is difficult. The part