Chairs and seats – Bottom or back – Framework
Patent
1998-04-20
1999-04-27
Brown, Peter R.
Chairs and seats
Bottom or back
Framework
298972, A47C 740
Patent
active
058971688
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention concerns a frame of a back-rest or seat made of metal for the seat of a motor vehicle. It further concerns a process for the manufacture of the frame.
2. Description of the Prior Art
In the manufacture of automobiles magnesium alloys are used because of their low specific gravity and their strength. Among the alloys, which consist essentially of magnesium, the so-called "electron metals" (or "Dow metals") may be worth considering; these are alloys consisting of 90% or more magnesium with--depending on the application additions of, for example, aluminum, zinc, manganese, copper or silicon, which are, in contrast to aluminum, insensitive to alkaline solutions, and which make weight savings of 80% as compared to iron possible, and even in comparison with aluminum alloys, such as Duralumin, weight savings of 20 to 40% are possible. By means of pickling them in a nitric acid containing alkaline dichromate bath, the electron metals can be given a coating, which protects them against being attacked by the atmosphere. Alloys of 98% magnesium and 2% manganese are practically permanently resistant to water.
In particular, the magnesium alloys with a high proportion of magnesium seem, therefore, to be predestined for the manufacture of vehicles, if weight savings combined with high mechanical strength are being desired. A problem in the application of magnesium for the production of the complicated support structures or frames of motor vehicle seats consists in the fact that magnesium cannot be spot welded. Therefore, if need be, only screws or rivets can be basically considered for the purpose of joining magnesium. The complicated core-containing dies, which are known from the support structure designs used for designing with steel, not only increase the cost of the dies, but generally also require substantial subsequent machining. Because in contrast to iron or steel profiles, cast magnesium profiles cannot be bent, the C-profiles typical for steel cannot be produced without complicated die work and efforts for removing parts from the dies, as well as with subsequent machining. But because the mechanical strength or the material hardness of magnesium and the alloys with a high proportion of magnesium is below that of steel, it is necessary in the case of the otherwise desirable substitution of magnesium for steel, to compensate for the reduced strength of the material, among other things, by the choice of the shape of the magnesium profile.
The invention is based on the problem of generating a magnesium profile for the support structure of a motor vehicle seat or the back rest pertaining to it, which can be die cast in one work process in such a way that not only the cost of the die used, but also the cost of removal from the die and of any possible subsequent machining are to be minimal.
The solution in accordance with the invention consists for support structure of the initially referred to type is that it be made according to a design--i.e. a structural assembly--which has a Z-profile as its basic geometry and consists of a magnesium die casting. According to a further aspect of the invention, the design is laid out for a magnesium die casting tool functioning in accordance with the "waffle iron principle". In a process according to the invention for the manufacture of a support structure, it is die cast in a single operation in a die according to the waffle iron principle, in which process preferably a die without a core is used. Improvements and further embodiments will be shown in the subordinate claims.
By virtue of the invention it is being achieved that the magnesium die cast part produced can be easily, that is to say by simply pulling an upper and a lower die apart, removed from the die. Subsequent machining is generally only needed at special locations, such as the areas for injecting material. Without any difficulty, a design is feasible which permits the dissipation of energy by deformation. According to the invention, the design spa
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Bartelt Regina
Domehl Thomas
Strenger Martin
Wissdorf Hubert
Zynda Martin
Brown Peter R.
Johnson Controls Technology Company
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