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
  • B29C45/46—Means for plasticising or homogenising the moulding material or forcing it into the mould
  • B29C45/53—Means for plasticising or homogenising the moulding material or forcing it into the mould using injection ram or piston
  • B29C45/54—Means for plasticising or homogenising the moulding material or forcing it into the mould using injection ram or piston and plasticising screw
  • B29C45/542—Means for plasticising or homogenising the moulding material or forcing it into the mould using injection ram or piston and plasticising screw using an accumulator between plasticising and injection unit, e.g. for a continuously operating plasticising screw
• • 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
  • B29C45/18—Feeding the material into the injection moulding apparatus, i.e. feeding the non-plastified material into the injection unit
• • 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
  • B29C45/46—Means for plasticising or homogenising the moulding material or forcing it into the mould
  • B29C2045/466—Means for plasticising or homogenising the moulding material or forcing it into the mould supplying the injection unit directly by a compounder
• • 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
  • B29C45/46—Means for plasticising or homogenising the moulding material or forcing it into the mould
  • B29C45/53—Means for plasticising or homogenising the moulding material or forcing it into the mould using injection ram or piston
  • B29C45/54—Means for plasticising or homogenising the moulding material or forcing it into the mould using injection ram or piston and plasticising screw
  • B29C2045/547—Means for plasticising or homogenising the moulding material or forcing it into the mould using injection ram or piston and plasticising screw continuously rotating plasticising screw cooperating with a single injection plunger

Definitions

• the invention relates to an injection molding machine according to the preamble of claim 1.
• An injection molding machine of this type is known from DE 195 05 984 A1, in which two piston injection devices, which are controlled by reversing valves and can be alternately filled with melt, are arranged after a screw plasticizing unit consisting of two synchronizing plasticizing screws.
• a screw plasticizing unit consisting of two synchronizing plasticizing screws.
• the functional division between a screw plasticizing unit on the one hand and a piston injection device on the other hand has the advantage that a screw plasticizing unit with optimal Plasticizing services can be used.
• Such a screw plasticizing unit can also be used in a particularly suitable manner for mixing in diverse components as a compounder if two plasticizing screws rotating in the same direction are used, the melt mixture product obtained in this way being able to be further processed in a subsequent injection molding process.
• the cyclical loading of one or more piston injection devices with the melt volume continuously generated by the screw plasticizing device can cause irregular pressure conditions in the immediate discharge area of the screw plasticizing device, which can have a negative effect on the plasticizing quality in the screw plasticizing device. This is particularly the case if several components are to be plasticized in the screw plasticizing device in a percentage ratio that must be observed exactly.
• the invention is therefore based on the object of eliminating interferences resulting from the cyclical spraying operation for the melt production with simple structural measures in an injection molding machine of the type mentioned and ensuring a uniform quality of the melt consisting of one or more components.
• Fig. 1 shows the basic diagram of a plasticizing unit consisting of a screw plasticizing device and a downstream piston injection device in an operating position at the end of the injection process and
• Fig. 2 shows the plasticizing unit according to Fig. 1 after the filling of
• the plasticizing unit 1 shows a plasticizing unit 1 of an injection molding machine, not shown in detail.
• the plasticizing unit 1 is supported on the machine frame 2 of the injection molding machine and can be moved thereon by means of a hydraulic device 3.
• the plasticizing unit 1 consists of a screw plasticizing device 4 and a piston injection device 5.
• the screw plasticizing device 4 is composed of a screw cylinder 6, in which a plasticizing screw 7 is mounted. Two plasticizing screws can also be arranged side by side, of which the second plasticizing screw is covered by the plasticizing screw 7 visible in the drawing. One or both plasticizing screws are coupled to a rotary drive (not shown).
• the worm cylinder 6 is designed with its outer contours as a piston and is displaceably mounted in a housing 9 by means of a hydraulic adjusting device 8.
• the housing 9 encloses a melt collecting space 10.
• a feed hopper 11 opens into the screw cylinder 6 and can be filled with product via a gravimetric metering device 12.
• a second product funnel 13 can be used to enter and compound a second product component into the screw flight via a second gravimetric metering device (not shown).
• a second gravimetric metering device not shown.
• several components can be entered into the son corner cylinder at the respective suitable plasticizing zones, the exact percentage composition being able to take place via several control-related gravimetric metering devices.
• the piston injection device 5 consists of an injection cylinder 15 enclosing a cylinder space 14, in which an injection piston 16 is guided.
• An injection line 17 leads from the cylinder space 14 to the injection nozzle 18, with which the plasticizing unit 1 is brought into contact with the fixed platen of the injection molding machine (not shown).
• the movement of the plasticizing unit 1 is accomplished by the hydraulic device 3 supported on the machine frame 2.
• the melt collecting space 10 and the cylinder space 14 are connected to one another via a melt line 19.
• a valve Vi is arranged in the melt line 19 and a valve V 2 is arranged in the injection line 17.
• the plasticizing unit 1 according to FIG. 1 is in an operating position at the end of the injection process and the plasticizing unit 1 according to FIG. 2 is in the operating position at the beginning of the injection process with the injection cylinder 15 completely filled.
• the melt collecting space 10 is filled with melt which is produced by one or two continuously running plasticizing screws 7.
• the screw cylinder 6 is loaded via one or more gravimetric metering devices in the required percentage composition.
• the decisive factor here is that the dynamic pressure P st of the melt in the melt collecting space 10 is always kept constant and above a value which corresponds to the pressure loss ⁇ p occurring in the melt line 19.
• the pressure P st in the melt collecting space 10 is kept constant by regulating the speed of the plasticizing screws 7 and / or by moving the melt cylinder 6 with the hydraulic adjusting device 8.
• the screw cylinder is moved from the position Pi to the position P2.
• a quantity of melt required for a spraying cycle has accumulated in the melt collecting space 10
• this is transferred into the cylinder space 14 of the piston injection device 5.
• the valve V 1 is opened and the valve V 2 is closed.
• the injection piston 16 is moved from its position P a (according to FIG. 1) to the position P D.
• the screw cylinder 6 moves from the position P 2 (according to FIG. 1) to the position Pi.
• the screw cylinder 6 is moved in such a way and / or the speed of the plasticizing screw 7 is set so that the melt collecting chamber 10 is always on constant dynamic pressure P st is maintained. Due to the dynamic pressure P st , which is always kept constant in front of the plasticizing screws 7, the production of melt in a constant quality is guaranteed in all operating phases.
• valve V 1 is closed and the melt from cylinder space 14 is injected via melt line 19 and open valve V 2 at injection pressure PE into the cavity (not shown) formed by the molds.
• the injection piston 16 assumes the position P a (according to FIG. 1).
• the screw cylinder 6 is retracted during the injection process and during the holding pressure phase, whereas the forward movement of the screw cylinder 6 takes place after the holding pressure phase has ended in order to transfer the melt from the full melt collecting chamber 10 into the cylinder chamber 14.
• the screw cylinder 6 and the injection piston 16 thus perform opposite directions during the injection phase and during the transfer phase.

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

Applications Claiming Priority (2)

Publications (1)

Family

ID=7646846

Family Applications (1)

Country Status (2)

Cited By (10)

Families Citing this family (3)

Citations (11)

Family Cites Families (3)

• 2000
  • 2000-06-30 DE DE2000131087 patent/DE10031087A1/de not_active Withdrawn
• 2001
  • 2001-06-12 WO PCT/EP2001/006611 patent/WO2002002293A1/de active Search and Examination

Patent Citations (11)

Non-Patent Citations (2)

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