Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
  • B29C45/17—Component parts, details or accessories; Auxiliary operations
  • B29C45/20—Injection nozzles
  • B29C45/23—Feed stopping equipment
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
  • B29C45/17—Component parts, details or accessories; Auxiliary operations
  • B29C45/26—Moulds
  • B29C45/27—Sprue channels ; Runner channels or runner nozzles
  • B29C45/28—Closure devices therefor
  • B29C45/2806—Closure devices therefor consisting of needle valve systems
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
  • B29C45/17—Component parts, details or accessories; Auxiliary operations
  • B29C45/26—Moulds
  • B29C45/27—Sprue channels ; Runner channels or runner nozzles
  • B29C45/28—Closure devices therefor
  • B29C45/2806—Closure devices therefor consisting of needle valve systems
  • B29C45/281—Drive means therefor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
  • B29C45/17—Component parts, details or accessories; Auxiliary operations
  • B29C45/26—Moulds
  • B29C45/27—Sprue channels ; Runner channels or runner nozzles
  • B29C45/28—Closure devices therefor
  • B29C45/2806—Closure devices therefor consisting of needle valve systems
  • B29C2045/2872—Closure devices therefor consisting of needle valve systems with at least three positions, e.g. two different open positions to control the melt flow
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
  • B29C45/17—Component parts, details or accessories; Auxiliary operations
  • B29C45/40—Removing or ejecting moulded articles

Definitions

• a second approach is to cause the gate nub to break off the molded part during mold opening and then eject the removed nub from the gate area when the mold is open.
• This is shown in Japanese Patent Application No. 52-151358, published December 15, 1977.
• the valve stem of a hot runner has a "gate puller" undercut machined into its end so that the gate nub solidifies and forms around the gate puller when the valve stem is in the gate closed position.
• the valve stem is retracted to break off the nub which then appears to fall free of the mold when the mold cavity is moved away from the hot runner system. This considerably complicates mold construction and does not appear to provide a foolproof nub removal and ejection system.
• valve gated hot runner in which the valve stem is moved to an intermediate position by means of a dual piston combination.
• the valve stem is first moved forward to open the valve gate and allow resin to fill the mold cavity.
• the valve stem is partially retracted to block the melt flow and allow a lower part of the valve stem to form the hole in the disc.
• the valve stem is fully retracted to pull its hole forming section out of the molded part and to allow the molded part to be ejected conventionally from the core side of the mold.
• the valve stem is advanced into the mold cavity to expose the air channel orifice in the valve stem and to allow it to assist in the mold opening and part ejection.
• a system such as this risks blocking the air passages during injection of the melt while the mold cavity is being filled. It is a principal object of the present invention to provide an improved injection nozzle system and method for injection molding which includes a movable valve stem and a valve gate nub area.
• the present invention provides an injection nozzle for injection molding plastic resin from a source of molten resin to a mold cavity, which comprises: a mold cavity; an injection nozzle with a nozzle body and a nozzle tip and having an internal flow channel therein communicating with an injection orifice which m turn communicates with said mold cavity for transportation of molten resm to the mold cavity; a valve gate nub area between the mold cavity and injection orifice; a valve stem mounted m the injection nozzle; and means to move the valve stem between an open position retracted from the injection orifice permitting the flow of resin to the mold cavity, a closed position blocking the injection orifice and preventing flow of resin to the mold cavity, and an advanced position within the valve gate nub area to assist m ejection of a molded part and to clear the valve gate nub area.
• the valve gate nub area includes a passageway between the mold cavity and injection orifice with an annular wall, where
• the present invention also provides a method for injection molding resin from a source of molten resin to a mold cavity which comprises: providing an injection nozzle with a nozzle body and a nozzle tip and having an internal flow channel therein communicating with an injection orifice which m turn communicates with a mold cavity; transporting molten resin from said internal flow channel to said mold cavity; positioning a valve gate nub area between the mold cavity and in j ection orifice; mounting a valve stem m the injection nozzle; and moving the valve stem between an open position retracted from the injection orifice permitting flow of resin to the mold cavity, a closed position blocking the injection orifice and preventing flow of resin to the mold cavity, and an advanced position within the valve gate nub area to assist m ejection of a molded part and to clear the valve gate nub area.
• Figure 1 is a sectional view through a nozzle assembly of the present invention with the valve gate open and the valve stem retracted;
• Figure 2 is a sectional view similar to Figure 1 with the valve gate closed and the valve stem m the closed position;
• Figure 3 is a sectional view similar to Figure 1 with the valve stem m the advanced position.
• Figures 1-3 show the nozzle assembly m each of three valve stem positions.
• Figure 1 shows injection nozzle 10 including nozzle housing 12 and nozzle tip 14 secured thereto.
• the injection nozzle is located m mold manifold plate 16 and supporting manifold 18.
• Mounted m manifold 18 is valve bushing 20 that contains two pneumatic pistons 22, 24 to which is attached valve stem 26.
• melt channel 28 in manifold 18 is connected to central melt channel 30 n nozzle housing 12 which m turn leads to injection orifice or gate orifice 32 m gate pad 34.
• Insulator 36 occupies the space between nozzle tip 14 and gate pad 34 and also contains a melt channel opening 38 therein.
• resin can be injected through the melt channels to fill mold cavity 40 m a known fashion.
• This mold cavity has a gate nub 42 so that when the mold cavity 40 and nub 42 are filled with resin a molded part is formed having a nub.
• Pneumatic pistons 22, 24 are operated by air pressure through lines 44, 46, 48 from a source of compressed air (not shown) such that by directing compressed air appropriately valve stem 26 can be moved to one of three positions.
• a source of compressed air not shown
• both pistons 22 and 24 are fully retracted by compressed air causing both of the pistons to move upward thereby fully retracting valve stem 26 within nozzle housing 12 and permitting resin to flow into the gate nub and mold cavity.
• m Figure 1 compressed air is introduced into line 48 causing piston 24 to retract and is also introduced into line 44 causing piston 22 to retract. This fully retracts valve stem 26.
• Figure 2 shows valve stem 26 m the gate closed position shutting off resin flow to the filled mold cavity 40 and to the filled gate nub 42.
• the valve stem is moved to the gate closed position shown m Figure 2 by introducing compressed air into line 44 to maintain piston 22 m the retracted position and also introduced into line 46 to advance piston 46 slightly forward and thus close injection orifice 32.
• Cooling channels 50 m gate pad 34 cause resm m the mold cavity 40 and gate nub 42 to solidify prior to opening the mold.
• Figure 3 shows valve stem 26 m the advanced position protruding into the gate nub area and thereby assisting m the ejection of the molded part as the mold is opened and also clearing any debris that may have accumulated m the gate nub area.
• the valve stem is moved to the advanced position shown m Figure 3 by exhausting air from line 44 to permit piston 22 to move forward and introducing compressed air into line 46 to move both pistons 22 and 24 forward.
• Debris can accumulate in front of the valve stem in the nub from a variety of causes such as; the stem is opened too soon by the operator in the process; or a short shot is molded (a partially filled cavity) wherein the partial molding sticks in the cavity and cannot be ejected normally from the core side of the mold; or if during maintenance the stem is operated manually dislodging frozen plastic in the area; or plastic may leak around the side of the stem and partially solidify in the nub area.
• valve stem 26 By advancing the valve stem 26 in accordance with the present invention as shown in Figure 3, prior to restarting, any such leakage or drool can be easily and conveniently pushed away from the gate area thereby completely clearing the gate area for a smooth restart of the molding operation.
• the present invention provides a simple and expeditious three position hot runner valve stem that can advance the valve stem into the mold cavity nub area to assist in part ejection during mold opening and also to clear debris from the area.

Landscapes

• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Mechanical Engineering (AREA)
• Moulds For Moulding Plastics Or The Like (AREA)
• Injection Moulding Of Plastics Or The Like (AREA)
• Diaphragms For Electromechanical Transducers (AREA)
• Casting Or Compression Moulding Of Plastics Or The Like (AREA)

Priority Applications (7)

Applications Claiming Priority (2)

Publications (1)

Family

ID=23269934

Family Applications (1)

Country Status (14)

Cited By (6)

Families Citing this family (15)

Citations (5)

Family Cites Families (7)

• 1999
  • 1999-06-04 US US09/325,895 patent/US6214275B1/en not_active Ceased
• 2000
  • 2000-04-05 KR KR10-2001-7015523A patent/KR100445948B1/ko not_active Expired - Fee Related
  • 2000-04-05 PT PT00915070T patent/PT1189739E/pt unknown
  • 2000-04-05 ES ES00915070T patent/ES2223484T3/es not_active Expired - Lifetime
  • 2000-04-05 JP JP2001501433A patent/JP2003508247A/ja active Pending
  • 2000-04-05 EP EP00915070A patent/EP1189739B1/en not_active Expired - Lifetime
  • 2000-04-05 DE DE60011898T patent/DE60011898T2/de not_active Expired - Fee Related
  • 2000-04-05 HK HK02107858.4A patent/HK1046255B/zh not_active IP Right Cessation
  • 2000-04-05 DK DK00915070T patent/DK1189739T3/da active
  • 2000-04-05 AT AT00915070T patent/ATE270177T1/de not_active IP Right Cessation
  • 2000-04-05 CA CA002373421A patent/CA2373421C/en not_active Expired - Fee Related
  • 2000-04-05 CN CN00808479A patent/CN1121933C/zh not_active Expired - Fee Related
  • 2000-04-05 WO PCT/CA2000/000365 patent/WO2000074920A1/en not_active Ceased
  • 2000-04-05 AU AU36513/00A patent/AU748547B2/en not_active Ceased

Patent Citations (5)

Non-Patent Citations (1)

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