Research On Moulding Technology For Instrument Panels

As the national economy is developing and the life level of citizen is lifting, the providing and demands of automobiles are increasing dramatically. Especially during the 21st century, the production and consumption of automobiles is increasing in an extremely high speed. With the rapid development of automotive industry, the quality's requirement of the instrument panel-- one of the most representative interior decoration parts, is demanding accordingly. Therefore studies to choose instrument panel materials, how to raise instrument panels' manufacture level and the moulding technology level, reduce instrument panels' manufacturing period, has outstanding economic significance.This paper studies the moulding technology of automotive instrument panels in the aspect of polyurethane(PU) foam and discusses the design of the PU foaming mould basically. The main tasks of this paper go as follows:(1) It introduces the definition, the catalog, cell structures, moulding principles, foaming methods and moulding equipments of PU foaming plastics. Furthermore, it elaborates the PU two-component liquid reactivity moulding technology which is the most active and developed most rapidly. Also, it makes a scrutiny into the gel reaction and froth reaction in the process of PU foaming runner moulding. It analyzes technology factors affecting parts quality in the process of runner foaming moulding theoretically so that it provides theoretical evidence of design of foaming components.(2) It summarizes the technology requirements of automotive instrument panels and analyzes the structures of automotive softening instrument panels. Then it selects materials of PU foaming buffering layers, frameworks and skins according to the manufacture and structure requirements of instrument panels. It emphasizes the foaming components, technology and properties of PU structure foaming. The results of the experiments show that mechanical properties of PU foam made of polyether polyols and polyisocyanate(PAPI) with functional proupos prove the best. The reaction is quite sensitive to the proportion and quantity of catalysts of organic stannum and amine. The silicone foaming stabilizer dramatically influences on properties of foam. The foaming agent F11 can be substituted by cyclopentane, which does no harm to the environment. Added powder filler and short glass fibres can considerably improve the impact strength and loss factor.(3) The moulding technology of the instrument panel is confirmed through analysis and research. The technology involves suction moulding with PVC/ABS skins, metal skeletons inside and PU runner moulding. By means of trial-manufacture, this paper analyzes the problems that the imprints of the surface can not be entirely eliminated, the thickness of skin is insufficient after moulding, the products are flanging, the panel interferes in the inside cavity of the product and setting up the cove of back panels. Then settlements are proposed accordingly. Furthermore, the foaming moulding technology parameters and skins moulding technology parameters are established on the basics above. Also, the operation principles of skins suction moulding and polyurethane runner moulding are established.(4) It introduces the test methods of instrument panels'appearance, size, luster, heat-resistance, low temperature-resistance, impact-resistance, flame retardance, solution resistance and peer strength. Automotive instrument panel products manufactured in this paper are tested in the indexes of dynamics, surface quality and mechanical properties. The results of the tests indicate that high temperature resistant, low temperature resistant, alternate heating/cooling cycles aging resistant and flame retardant properties of products are all qualified as the desired standards. Therefore the plan is available and can be put into practice.(5) PU foaming moulds are basically discussed and general flows are introduced. Technology requirements of parts are summarized in the aspects of demoulding rake, wall thickness, the rib, the support surface, circle rape and holes. The design of processing mould structure and the computation method of working sizes of processing mould parts are presented. How to select runner systems, demoulding systems, and sealing systems is analyzed. Therefore evidence of PU foaming mould design is theoretically provided.