Metal deforming – By extruding through orifice – Expressing non-uniform cross-section or non-linear product
Patent
1996-08-23
1998-07-07
Larson, Lowell A.
Metal deforming
By extruding through orifice
Expressing non-uniform cross-section or non-linear product
72468, 72 3113, 72377, B21C 2508
Patent
active
057751552
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a variable section extrusion die set and to a variable section extrusion molding method which is usable when a molding material (such as aluminum or the like) is subjected to extrusion molding, thereby forming, in particular, a molded product which varies in cross sectional shape in its longitudinal direction.
BACKGROUND ART
Recently, in various types of automotive vehicles such as common automobiles, trucks, and the like, components such as the chassis, vehicle main-frames, bumpers, and the like, which are made of aluminum or aluminum alloy, have been widely used instead of parts which are conventionally made of iron, because aluminum chassis, etc., are desirable, especially with respect to reducing the weight of vehicle main-frames, prolonging the service life of vehicles, recycling considerations, etc.
When manufacturing these types of vehicle components, it is ordinary practice to use an extrusion process. The reason for this is that the melting point of aluminum used as a raw material is low. In such an extrusion process, an extrusion die set having a hole portion which has a configuration similar in cross section to those of the vehicle components is firmly secured to a distal end portion of a container, a heated material (billet) is inserted into the interior of the container, and then the billet is pressed towards the extrusion die set side so that the former is extruded out of the hole portion, thereby forming the above-mentioned vehicle components. According to this extrusion procedure, since the hole portion of the extrusion die set has a constant cross sectional shape, the vehicle components which are thus obtained each have a constant cross sectional shape in the longitudinal direction.
It is interesting to note, however, that among the above-mentioned vehicle components, a chassis side-frame, for example, has a bending stress distribution such that a bending stress exerted thereon is large at the central area or at opposite end portions each serving as a fulcrum in the longitudinal direction, but is small at the central portion. Accordingly, when the conventional extrusion die set is used for shaping, the resultant side-frame has a constant sectional configuration in the longitudinal direction. In other words, due to a constant sectional secondary moment, the resultant side-frame tends to have an excessively large dimension and strength which are greater than necessary at the central portion. This means that some molding material is likely to be wasted, and this is therefore economically inefficient. Moreover, there are other problems such as the inability to meet the requirements for a compact installation space and a light-weight design of the vehicle components.
In an attempt to avoid the above problems, there was proposed an improved extrusion die set and extrusion molding method in Japanese Patent Application Laid-Open No. 31527/93, as shown in FIG. 33 of the attached drawings of the present application.
An extrusion die set according to the teaching of the above Laid-Open Publication comprises a stationary die 1 secured to a container and a movable die 2 which can move relative to the stationary die 1. The stationary die 1 includes a first die hole 3 which defines a web, a second die hole 4 extending at right angles from an upper end of the first die hole 3 to define a flange, and a third die hole, similarly extending at right angles, but from a lower end of the first die hole 3. The third die hole 5 is equal in length to, but is larger in width than, the second die hole 4. In contrast, the movable die 2 includes a first movable die hole 6 which communicates with the first die hole 3, and a second die hole 7 which communicates with the third die hole 5 and defines another flange.
According to an extrusion die set which is constructed in this manner, by appropriately moving the movable die 2 in directions as indicated by a two-headed arrow in FIG. 33, the length of the web of a component to be shaped can be varied in the longitudinal directio
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patent: 5321967 (1994-06-01), Wakabayashi
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Hiyoshi Yasumasa
Kamibayashi Atsushi
Kato Masatsugu
Sano Shigeo
Larson Lowell A.
Mitsubishi Aluminum Co. Ltd.
Tolan Ed
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