Solid material comminution or disintegration – Processes – With application of fluid or lubricant material
Reexamination Certificate
1998-10-28
2001-02-13
Rosenbaum, Mark (Department: 3725)
Solid material comminution or disintegration
Processes
With application of fluid or lubricant material
C241S073000, C241S074000, C241S065000
Reexamination Certificate
active
06186424
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and an apparatus for manufacturing chips for a thixomolding-process injection molding machine, and more particularly to novel improvements for manufacturing a high-purity raw material for recycling by charging into a chip manufacturing device primary crushed pieces obtained by fragmenting and crushing wastes occurring during the molding of a metal alloy and wastes of metal alloy products, and by processing them into chips whose surfaces are polished and in which impurities are removed.
2. Related Art
Conventionally, in a process for molding a magnesium alloy, for example, a die-casting process is generally adopted in which a melt of 620 to 700° C. which is completely melted in a melting furnace is cast into a mold at high pressure.
In contrast, the thixomolding process is a molding process in which a chip-like raw material of a metal alloy is charged into a hopper, and the chips are heated above a solidifying point and below a melting point inside a cylinder by a heater, are thus set in a semimolten state in which the liquid phase and the solid phase coexist, and are poured into a mold.
This injection molding process excels over the die-casting process in the following points:
(1) A melting furnace is not required for the plant.
(2) A large-scale fire-prevention measure is not required for the plant.
(3) A covering flux is not required.
(4) Treatment of dross and sludge is not required.
(5) Melting skills and experience are not required.
(6) The energy cost can be reduced.
(7) Since the raw material with a grain size of 1 to 8 mm is used, there is no possibility of the chips being ignited.
(8) The dendrite (a crystal with a treelike branching pattern) is crushed by a screw and is formed into fine particles with diameters of 35 to 75 mm, and the fluidity of the semimolten metal increases, so that moldings with thin wall thicknesses can be formed.
(9) A completely molten metal whose viscosity is low is liable to form a turbulent flow, but the flow of a semimolten metal whose viscosity is high becomes closer to a laminar flow, so that the amount of a gas entrained is small, and bubbles are therefore difficult to be formed in moldings.
(10) Since the semimolten metal solidifies faster than the completely molten metal, it is possible to reduce the molding cycle time.
(11) The life of the mold can be extended.
(12) The dimensional accuracy improves.
(13) The working environment is excellent.
Partly due to a move toward enactment of a “Household Electrical Appliance Recycling Law,” Japanese and foreign major consumer electrical appliance manufacturers, automobile manufacturers, and injection molding manufacturers have en bloc shifted to magnesium alloy moldings that are 100% recyclable and are produced by injection molding which is superior to the die-casting process.
In addition, the magnesium alloys have such characteristics as a heat radiating characteristic and an electromagnetic-wave shielding characteristic in addition to its light weight, thin size, and high rigidity, and is capable of expressing a higher-quality feature than an alloy resin body. Thus, the magnesium alloys have outstanding characteristics.
On the other hand, in the conventional regeneration of magnesium alloy scraps, the scraps are remelted and refined to form ingots, and the ingots were formed into chips again so as to be used.
Although recycling is 100% possible according to the above-described conventional method, a large amount of energy is required, and countermeasures against pollution and waste treatment, including the treatment of exhaust gases, dross, and sludge, are required, resulting in high cost.
SUMMARY OF THE INVENTION
The present invention has been devised to overcome the above-described problems, and its object is to provide a method and an apparatus for manufacturing chips for a thixomolding-process injection molding machine for manufacturing a high-purity raw material for recycling by charging into a chip manufacturing device primary crushed pieces obtained by fragmenting and crushing wastes occurring during the molding of a metal alloy and wastes of metal alloy products, and by processing them into chips whose surfaces are polished and in which impurities are removed.
The method for manufacturing chips for a thixomolding-process injection molding machine in accordance with the present invention comprises: a first step of charging primary crushed pieces, which are obtained by fragmenting and crushing wastes produced at the time of molding a metal alloy as well as wastes of metal alloy products, into a chip manufacturing apparatus having fixed blades, rotating blades, and a screen; a second step of causing the primary crushed pieces to be cut and fragmented by the fixed blades and the rotating blades, and causing the cut and fragmented pieces to pass through and fly outside the screen so as to obtain chips; and a third step of forcedly exhausting a powder mixed with the chips. Further, in this method, the primary crushed pieces have lengths and thicknesses of approximately 5 to 30 mm. Further, in this method, the powder is collected. Further, in this method, the surfaces of the chips are polished during cutting and fragmenting by the fixed blades and the rotating blades. Further, in this method, any one of an aluminum alloy, a zinc alloy, and a magnesium alloy is used as the metal alloy. In addition, the apparatus for manufacturing chips for a thixomolding-process injection molding machine comprises: fixed blades and rotating blades provided inside a chamber; a mesh-like screen provided in a side portion of the chamber; and a chip takeout port provided on an outer side of the screen, wherein primary crushed pieces, which are obtained by fragmenting and crushing wastes produced at the time of molding a metal alloy as well as wastes of metal alloy products, are charged into the chamber and are crushed by the fixed blades and the rotating blades so as to obtain chips, and the chips which have passed through the screen are collected. Further, cooling vanes are provided above the rotating blades, and a coarse surface plate is provided on a bottom portion of the chamber.
REFERENCES:
patent: 2873663 (1959-02-01), Hawk et al.
patent: 2886254 (1959-05-01), Rohlinger et al.
patent: 2890840 (1959-06-01), Fletcher et al.
patent: 3378210 (1968-04-01), Bambach
patent: 3986676 (1976-10-01), Husmann
patent: 4934614 (1990-06-01), Lewis
Kitamura Kazuo
Uno Tadashi
Rosenbaum Mark
Sughrue Mion Zinn Macpeak & Seas, PLLC
The Japan Steel Works Ltd.
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