Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
  • B22D17/20—Accessories: Details
  • B22D17/2015—Means for forcing the molten metal into the die
  • B22D17/2061—Means for forcing the molten metal into the die using screws
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
  • B22D17/007—Semi-solid pressure die casting
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S164/00—Metal founding
  • Y10S164/90—Rheo-casting

Definitions

• the present invention is for an improvement of an apparatus for the injection molding of a metal alloy.
• a sub-ring is placed under a piston ring on a sliding seal ring of a nonreturn valve assembly.
• the sub-ring seals the pressure and metal flow in the apparatus, virtually eliminates piston ring leakage and extends the usable life of the non-return valve assembly.
• the method and apparatus improve the injection molding process by establishing and maintaining a temperature profile for a given alloy by heating the alloy in a screw extruder to a temperature above its solidus temperature and below its liquidus temperature and, prior to the injection stroke, avoiding the imposition of any appreciable increase of force on the alloy. This is accomplished by delivering the semi-solid material to an accumulation space or zone between the extruder nozzle and the extruder screw tip and withdrawing or retracting the screw, while it rotates, in a direction away from the discharge nozzle as the space between the nozzle and the tip of the screw is filled with material.
• the retraction of the extruder screw is accomplished by pressure buildup in the space between the nozzle and the extruder screw tip.
• U.S. Patent 4,501,550 discloses an injection molding apparatus for resin materials.
• the apparatus does not include a non-return valve having a piston ring with a sub-ring.
• Figure 1 is a schematic side view, partly in section, of an apparatus for injection molding a metallic material.
• Heating zone Z5 utilizes a band resistance heater 42 capable of supplying up to 0.75 kw to maintain a first, relatively high temperature in the upstream portion of the nozzle 20.
• Heating zone Z6 utilizes a band or coiled resistance heater 43 capable of supplying up to 0.6 kw and maintains a second, relatively lower temperature in the remainder of nozzle 20 and particularly in the nozzle tip 20a.
• Fig. 2 further illustrates that the feed material is delivered into the barrel 14 adjacent its rear or upstream end. At this end of the barrel only limited heating occurs, but granules of material are introduced by the screw 16 and moved forwardly, or downstream into heating zone Zl and subjected to preliminary heating by the heater 37. The material then is advanced further downstream and subjected to the more pronounced and drastic heating of induction coil 38 at heating zone Z2.
• the determining factor in selecting temperatures is the percentage of solids desired during the final injection molding shot. Mold gating design also may have an effect on selection of temperatures.
• the non-return valve assembly 18 is best illustrated in Fig. 3.
• the extruder screw 16 terminates with the non-return valve assembly 18.
• the function of the non-return valve assembly 18 is to seal and stop back flow of material into the extruder screw 16.
• the pressure ahead of the tip 19 can reach 20,000 psi (normal operating pressure is about 10,000 psi) with the pressure behind check ring 45 at atmospheric pressure.
• the quality of the components produced by the apparatus is directly related to how well the non-return valve seal is maintained. We have seen a 30% increase in the life of the seal with the introduction of the sub-ring 47.
• the sub-ring 47 is installed directly under the last piston ring 46 on the sliding seal ring 44 (see Figs. 3 and 4) .
• the sub-ring 47 is a two-piece semi- circular assembly (Figs. 6A and 6B) .
• the overlapping gaps 52 in the sub-ring are in the opposite direction of the piston ring gaps 49 (Fig. 7) .
• the orientation of the gaps in the sub-ring prevent the high pressure semi-molten alloy from flowing out through the piston ring gaps even as the piston ring gaps increase with wear.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Injection Moulding Of Plastics Or The Like (AREA)

Priority Applications (7)

Applications Claiming Priority (2)

Publications (1)

Family

ID=24956161

Family Applications (1)

Country Status (8)

Families Citing this family (36)

Citations (3)

Family Cites Families (19)

• 1996
  • 1996-10-23 US US08/735,526 patent/US5680894A/en not_active Expired - Fee Related
• 1997
  • 1997-07-30 EP EP97934352A patent/EP0946319B1/en not_active Expired - Lifetime
  • 1997-07-30 CA CA002269676A patent/CA2269676C/en not_active Expired - Fee Related
  • 1997-07-30 JP JP51933698A patent/JP2002514136A/ja active Pending
  • 1997-07-30 AU AU37431/97A patent/AU3743197A/en not_active Abandoned
  • 1997-07-30 AT AT97934352T patent/ATE218080T1/de active
  • 1997-07-30 DE DE69712913T patent/DE69712913T2/de not_active Expired - Fee Related
  • 1997-07-30 WO PCT/US1997/013434 patent/WO1998017419A1/en not_active Ceased

Patent Citations (3)

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