Metal deforming – Tool and/or tool holder
Patent
1990-04-16
1992-01-21
Larson, Lowell A.
Metal deforming
Tool and/or tool holder
761071, B21D 3701
Patent
active
050818619
DESCRIPTION:
BRIEF SUMMARY
FIELD OF ART
The present invention relates to a resin die for sheet metal pressing and a method for producing same. Particularly, the present invention is concerned with a resin die for sheet metal pressing and a method for producing same in which a reinforcing member is incorporated in the die and punch shoulder portions of the sheet metal pressing resin die to ensure sufficient strength and durability, the said reinforcing member being obtained by impregnating a deformed vortex-like multi-layer body formed of reinforcing fibers with a thermosetting resin followed by curing.
BACKGROUND ART
Conventional practical resin dies for sheet metal pressing have been manufactured by a lamination method or a metal core method. First, the lamination method will be outlined below with reference to FIG. 14.
In FIG. 14, the numeral 20 denotes a core box. Within the core box 20 there is fixed a model 21 formed of wood, synthetic wood, gypsum, or the like. A releasing agent is applied to the inner surface of the core box 20 and the surface of the model 21, and a resin for the surface layer is applied onto the releasing agent to form a surface resin layer 22. When the surface layer resin was semi-cured, resin-impregnated fibers are stuck thereon to form a reinforcing layer 23. At this time, in conformity with local shapes of the die various resin-impregnated fibers are used properly so as to be compatible with such local shapes. For example, a woven cloth is used for a flat portion, or short fibers are used or short-cut woven cloth pieces are joined together for a curved portion. In a corner or a small curve, roving pieces cut in an appropriate length are embedded.
The space inside the reinforcing layer 23 is filled with a sand or short fibers-incorporated resin. Upon curing of that resin, there is obtained a sand core 24. Then, a levelling resin is applied onto the whole, which is then covered with a horizontal plate 25, allowing the resin to be cured. As a result, a levelling layer 26 is formed.
After curing of all the resins, the cured resinous body is taken out from the core box 20 to afford a finished resin die, in which the surface resin layer 22 is formed outside, the reinforcing layer 23 using a fiber-reinforced resin is formed inside the surface resin layer 22, the sand core 24 is formed inside the reinforcing layer 23, and the levelling layer 26 is formed as an upper surface layer.
The metal core method, which has also been used practically in addition to the lamination method, will now be outlined with reference to FIG. 15. A core 27 made by metal casting and having an external form smaller by 10 to 20 mm than the size of a die is prepared. In this case, an inlet 28 is formed in the core 27. A model 21 is fixed within the core box 20 and a releasing agent is applied to the model. Then, a small cured piece of a casting resin having a thickness corresponding to the thickness of the casting resin is disposed as a spacer, on which is then placed the core 27. The casting resin is poured from the inlet 28 to fill the space between the core 27 and the core box 20 and the space between the core 27 and the model 21. After the resin was cured and became integral with the core 27, the integral body is taken out to find that a resin layer 29 is formed on the outer periphery except the upper surface. By cutting and thereby levelling the upper surface there is obtained a resin die having desired shape and size.
In this resin die, the resin layer 29, which has a thickness of 10 to 20 mm, is formed on the outer periphery except the upper surface, and the metallic core 27 is present inside the resin layer 29. The resin layer 29 and the core 27 are bonded together as an integral body by virtue of a bonding force created at the time of curing of the resin
The sheet metal pressing work is based on a forming method wherein a blank holding pressure is applied to a blank such as a cold-rolled steel sheet inserted between the die surface and the blank holding surface, and in this state a punch is press-fitted in the blank to effect
REFERENCES:
patent: 3041131 (1962-06-01), Juras et al.
patent: 4919876 (1990-04-01), Savage et al.
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