WO2024068874A1 - Machine de moulage par injection de matière plastique et procédé permettant de faire fonctionner une machine de moulage par injection de matière plastique - Google Patents

Machine de moulage par injection de matière plastique et procédé permettant de faire fonctionner une machine de moulage par injection de matière plastique Download PDF

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Publication number
WO2024068874A1
WO2024068874A1 PCT/EP2023/076958 EP2023076958W WO2024068874A1 WO 2024068874 A1 WO2024068874 A1 WO 2024068874A1 EP 2023076958 W EP2023076958 W EP 2023076958W WO 2024068874 A1 WO2024068874 A1 WO 2024068874A1
Authority
WO
WIPO (PCT)
Prior art keywords
evaporation chamber
pressure
valve
molding machine
injection molding
Prior art date
Application number
PCT/EP2023/076958
Other languages
German (de)
English (en)
Inventor
Andreas Röders
Original Assignee
G.A. Röders Holding Gmbh & Co. Kg
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by G.A. Röders Holding Gmbh & Co. Kg filed Critical G.A. Röders Holding Gmbh & Co. Kg
Publication of WO2024068874A1 publication Critical patent/WO2024068874A1/fr

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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
    • B29C33/00—Moulds or cores; Details thereof or accessories therefor
    • B29C33/02—Moulds or cores; Details thereof or accessories therefor with incorporated heating or cooling means
    • B29C33/04—Moulds or cores; Details thereof or accessories therefor with incorporated heating or cooling means using liquids, gas or steam
    • 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
    • B29C33/00—Moulds or cores; Details thereof or accessories therefor
    • B29C33/02—Moulds or cores; Details thereof or accessories therefor with incorporated heating or cooling means
    • B29C33/04—Moulds or cores; Details thereof or accessories therefor with incorporated heating or cooling means using liquids, gas or steam
    • B29C33/046—Moulds or cores; Details thereof or accessories therefor with incorporated heating or cooling means using liquids, gas or steam using gas
    • 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
    • B29C35/00—Heating, cooling or curing, e.g. crosslinking or vulcanising; Apparatus therefor
    • B29C35/007—Tempering units for temperature control of moulds or cores, e.g. comprising heat exchangers, controlled valves, temperature-controlled circuits for fluids
    • 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
    • B29C35/00—Heating, cooling or curing, e.g. crosslinking or vulcanising; Apparatus therefor
    • B29C35/16—Cooling
    • 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
    • B29C45/72—Heating or cooling
    • B29C45/73—Heating or cooling of the mould
    • B29C45/7306—Control circuits 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
    • B29C45/72—Heating or cooling
    • B29C45/73—Heating or cooling of the mould
    • B29C45/7337—Heating or cooling of the mould using gas or steam
    • 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
    • B29C35/00—Heating, cooling or curing, e.g. crosslinking or vulcanising; Apparatus therefor
    • B29C35/16—Cooling
    • B29C2035/1616—Cooling using liquids
    • 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
    • B29C2945/00—Indexing scheme relating to injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould
    • B29C2945/76—Measuring, controlling or regulating
    • B29C2945/76003—Measured parameter
    • B29C2945/76006—Pressure
    • 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
    • B29C2945/00—Indexing scheme relating to injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould
    • B29C2945/76—Measuring, controlling or regulating
    • B29C2945/76003—Measured parameter
    • B29C2945/7604—Temperature
    • 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
    • B29C2945/00—Indexing scheme relating to injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould
    • B29C2945/76—Measuring, controlling or regulating
    • B29C2945/76177—Location of measurement
    • B29C2945/76297—Fluids
    • B29C2945/76304—Fluids temperature control fluids

Definitions

  • the invention relates to a plastic injection molding machine and a method for operating a plastic injection molding machine.
  • a plastic material in a liquid or pasty state is injected into a cavity of an injection mold.
  • the plastic material cools and turns into a solid state.
  • An injection molded part is created that has a shape corresponding to the cavity.
  • the injection mold can be opened to remove the injection molded part from the mold.
  • the injection mold comprises a mold core that extends into the cavity of the injection mold.
  • An evaporation chamber can be arranged within the mold core, in which a liquid is evaporated when the plastic material cools in order to extract heat from the plastic material in the area around the mold core. It is known that the temperature at which the liquid evaporates can be influenced by adjusting the pressure in the evaporation chamber, WO 2019/158521 Al.
  • the liquid evaporates at a higher temperature, so that a smaller amount of heat is removed from the plastic material.
  • a reduced cooling effect can be useful, for example, in applications in which the structure of the plastic material would change adversely due to cooling that is too strong and too fast. It has turned out that it is not entirely easy to adjust the pressure conditions in the evaporation chamber so that the plastic material is cooled to an appropriate extent.
  • the invention is based on the object of presenting an injection molding machine and a method for operating an injection molding machine with which these disadvantages are avoided.
  • the task is solved with the features of the independent claims.
  • Advantageous embodiments are specified in the subclaims.
  • the plastic injection molding machine comprises an injection mold, a feed unit for injecting a plastic material into a cavity of the injection mold and a cooling device for the injection mold.
  • the injection mold has a mold core that projects into the cavity and is provided with an evaporation chamber.
  • a pressure source is connected to the evaporation chamber and is designed to generate excess pressure in the evaporation chamber.
  • the cooling device comprises a high-pressure pump arranged upstream of the evaporation chamber for conveying a liquid into the evaporation chamber and an overflow valve arranged downstream of the evaporation chamber. The opening pressure of the overflow valve is higher than the pressure generated by the pressure source.
  • the invention has recognized that the combination of the pressure source and the overflow valve makes it possible to generate the desired pressure conditions for the evaporation process in the evaporation chamber.
  • a pressure increase occurs as soon as liquid is pumped into the evaporation chamber by the high-pressure pump.
  • the increased pressure spreads to the Overflow valve so that the overflow valve opens and the pressure in the evaporation chamber is limited by the opening pressure of the overflow valve.
  • a high-pressure pump in the sense of the invention is designed to convey the liquid at a pressure of at least 5 bar towards the evaporation chamber.
  • One effect of the increased pressure in the evaporation chamber is that the amount of liquid that is fed to the evaporation chamber in a given operating state of the high-pressure pump is reduced.
  • the pressure generated by the pressure source in the evaporation chamber can be 0.5 bar to 10 bar, preferably 1 bar to 5 bar, higher than atmospheric pressure. If the liquid is water, the evaporation temperature at atmospheric pressure is 100 ° C. The evaporation temperature increases to about 120 ° C at a pressure of 2 bar and to about 133 ° C at a pressure of 3 bar.
  • the opening pressure of the overflow valve can be slightly higher than the pressure in the evaporation chamber, so that the overflow valve opens quickly after the delivery process begins. For example, the opening pressure of the overflow valve can be between 2% and 20% higher than the excess pressure in the evaporation chamber generated by the pressure source.
  • a relief valve is a valve that opens when the differential pressure above the overflow valve is greater than a predetermined opening pressure, and this closes when the differential pressure is smaller than the opening pressure. Atmospheric pressure can be present on the side of the overflow valve facing away from the pressure chamber.
  • a branch is formed between the evaporation chamber and the overflow valve, wherein the pressure source is connected to the branch.
  • the branch arranged between the evaporation chamber and the valve can be designed such that the overflow valve is arranged in a first arm of the branch and the valve is arranged in a second arm of the branch.
  • a valve can be arranged between the branch and the pressure source, which is open in a first state and closed in a second state. The valve can be opened in order to apply an overpressure in the evaporation chamber from the pressure source. The valve can be closed when an overpressure in the evaporation chamber is relieved via the overflow valve.
  • the valve can additionally or alternatively be closed when gas and/or liquid is discharged from the evaporation chamber, bypassing the overflow valve.
  • the disclosure also encompasses embodiments in which there is neither a valve nor a branch between the evaporation chamber and the pressure source.
  • the valve can be a valve arranged between the evaporation chamber and the pressure source, which counteracts a backflow from the evaporation chamber into the pressure source.
  • the valve can be designed as a check valve that closes when the pressure on the side facing the evaporation chamber is higher than the pressure on the side facing the pressure source. It is also possible to have a switchable valve that is appropriately controlled via control commands. In this way it can be ensured that a pressure increase triggered by the conveying process does not affect the pressure source.
  • the valve can be a check valve arranged between the evaporation chamber and the pressure source.
  • the check valve can be designed to be switched between the first state and the second state by a control signal.
  • the check valve can be opened to generate the overpressure in the evaporation chamber from the pressure source.
  • the check valve can be closed to allow excess pressure to be released from the evaporation chamber without gas being able to escape from the pressure vessel via the same route.
  • a check valve and a shut-off valve are connected in series between the branch and the pressure source, so that the gas passes through the check valve and the shut-off valve on its way from the pressure source into the evaporation chamber. If one of the two valves connected in series is closed, no gas can pass through.
  • the effect of the valves connected in series can be combined in a switchable valve if, in addition to the switching processes described in connection with the shut-off valve, the switchable valve is controlled in such a way that the switchable valve closes while the excess pressure from the evaporation chamber is reduced via the overflow valve.
  • the pressure source can include a source area in which there is an output pressure that is higher than the pressure to be applied in the evaporation chamber.
  • the source area can be, for example, a pressure reservoir or a line under the corresponding pressure.
  • a pressure reducer can be arranged between the source area and the evaporation chamber which is set to the pressure that should be present in the evaporation chamber.
  • the pressure in the evaporation chamber can be adjusted with the desired precision using such a pressure reducer.
  • the pressure reducer can be adjustable so that the pressure can be freely selected within the adjustment range of the pressure reducer.
  • the pressure can be adjustable in stages or continuously.
  • the adjustment range can cover the range from 1 bar to 5 bar, preferably the range from 0.5 bar to 7 bar.
  • the information refers to the excess pressure by which the pressure is higher than atmospheric pressure.
  • the cooling device can comprise a central module from which the liquid is supplied to an outlet opening leading into the evaporation chamber.
  • the liquid can be supplied through a liquid line extending between the central module and the outlet opening.
  • the central module can comprise a high-pressure pump with which the liquid is conveyed to the outlet opening.
  • the mold core can extend from a proximal end adjacent to the body of the injection mold to a distal end.
  • the distal end can form a free end in the cavity.
  • a distal section of the mold core adjacent to the distal end preferably has a largest diameter of no more than 20 mm, preferably no more than 10 mm, more preferably no more than 7 mm. The largest diameter is generally not smaller than 3 mm.
  • the section adjacent to the distal end can extend over at least 30%, preferably at least 50%, more preferably at least 70% of the length that the mold core projects into the cavity.
  • the evaporation chamber can be arranged adjacent to the distal end of the mold core.
  • a first channel can be formed within the mold core, through which the liquid is supplied to the evaporation chamber.
  • the first channel forms a section of the liquid line between the central module and the outlet opening.
  • a second channel can be formed within the mold core, through which the gas-liquid mixture is discharged from the evaporation chamber.
  • the cross-sectional area of the second channel can be larger than the cross-sectional area of the first channel, preferably at least by a factor of two, more preferably at least by a factor of five, further preferably at least by a factor of ten.
  • the first channel extends inside the tube and the second channel inside the annular channel. The reverse design is also possible.
  • the tube can be designed as a capillary tube within which the first channel extends.
  • the capillary tube can comprise an outlet opening opening into the evaporation chamber.
  • the diameter of the channel formed in the capillary tube can be, for example, between 0.5 mm and 2 mm, preferably between 0.8 mm and 1.2 mm.
  • a section of the liquid line arranged between the inlet side of the capillary tube and the central module can have a diameter that is significantly larger than the diameter of the tube.
  • the high-pressure pump delivers liquid through the liquid line to the outlet opening.
  • the liquid can be under a pressure that is significantly higher than the pressure generated by the pressure source in the evaporation chamber.
  • the pressure of the liquid can be at least 5 bar, preferably at least 10 bar, more preferably at least 20 bar higher than the pressure in the evaporation chamber. This prevents the liquid from evaporating before it enters the evaporation chamber.
  • the injection mold is closed so that the cavity forms a closed cavity.
  • the plastic material is injected into the cavity in a liquid or pasty state using the feed unit, so that the cavity is filled with the plastic material.
  • the injection phase can last a few seconds, for example between 0.2 s and 5 s.
  • pressure continues to be exerted from the feed unit onto the plastic material in the cavity during a pressing phase.
  • the pressing phase ends when quantities of the plastic material adjacent to the feed unit have hardened, so that the pressure no longer acts on quantities of the plastic material removed from the feed unit.
  • the length of the pressing phase can be between 2 s and 50 s, for example.
  • the remaining time in which the plastic material hardens is called the residual cooling time.
  • the length of the remaining cooling time can be between 2 s and 50 s, for example.
  • the delivery phase in which liquid is delivered into the evaporation chamber by the high-pressure pump, begins after the start of the working cycle and ends before the end of the working cycle.
  • the start of the delivery phase is preferably after the end of the injection phase.
  • the delivery phase is preferably ended before the injection mold is opened again.
  • the high-pressure pump can be set up so that between the start of the Liquid is continuously pumped into the evaporation chamber between the pumping phase and the end of the pumping phase. Intermediate interruptions in pumping would in principle be possible. However, this approach would have the disadvantage that the cooling effect could not be adjusted very precisely because short pumping pulses are difficult to dose.
  • the cooling effect is reduced by the excess pressure in the evaporation chamber according to the invention.
  • this is because the evaporation temperature increases with increasing pressure.
  • the pressure difference compared to the pressure applied by the high-pressure pump decreases, which means that the amount of liquid entering the evaporation chamber is reduced.
  • the pressure in the evaporation chamber is the key variable with which the cooling process can be influenced.
  • the pressure in the evaporation chamber is set so that, on the one hand, the cycle time for a working cycle of the injection molding machine can be kept as short as possible, while, on the other hand, excessive cooling of the plastic material in the vicinity of the mold core is avoided.
  • the appropriate value for the pressure is determined from application to application using these criteria.
  • the initial conditions are known at the beginning of a funding phase.
  • the liquid line between the central module and the outlet opening is complete filled with liquid, the liquid emerges into the evaporation chamber without delay as soon as the liquid in the central module is pressurized.
  • a second valve can be arranged in the liquid line.
  • the second valve can be open in the delivery phase.
  • the second valve can be closed outside the delivery phase if there is excess pressure in the evaporation chamber.
  • the second valve can be designed as a second check valve, which closes when the pressure on the side facing the evaporation chamber is higher than the pressure on the side facing the central module. It is also possible for the second valve to be a switchable valve that is controlled in a suitable manner with control signals.
  • a second branch can be formed in the liquid line between the outlet opening and the central module, so that a section of the liquid line lying between the second branch and the outlet opening can be blown out.
  • a gas line can be connected to the branch, the other end of which is fed from the central module.
  • the evaporation chamber can be blown out via the gas line between the end of a first conveying phase and the start of a subsequent conveying phase, so that defined initial conditions are present for the next conveying process.
  • the defined initial conditions include that the section of the liquid line lying between the second branch and the outlet opening is not filled with liquid.
  • the second valve can be arranged between the outlet opening and the branch. I is the second valve between The branch and the central module are arranged, a third valve can be provided in the gas line in order to prevent the gas from flowing back in the direction of the central module if there is excess pressure in the evaporation chamber.
  • the third valve can be designed as a third check valve. It is advantageous if the second valve is arranged close to the conveyor core.
  • the section of the liquid line between the central module and the second valve is preferably larger, more preferably at least twice as large, more preferably at least three times as large as the section of the liquid line between the second valve and the outlet opening.
  • the pressure in the evaporation chamber can be higher than the pressure previously generated by the pressure source. It can be advantageous to release the pressure from the evaporation chamber before the next conveying process.
  • a second shut-off valve can be provided through which the gas-liquid mixture can escape from the evaporation chamber, bypassing the overflow valve.
  • the second shut-off valve can be designed in such a way that it can be switched between an open state and a closed state by control signals.
  • the cooling device may include a return line that extends between the evaporation chamber and the central module.
  • the overflow valve can be arranged in the return line, so that quantities of the gas-liquid mixture passing through the overflow valve are returned to the central module.
  • the second check valve can be connected in parallel to the overflow valve within the return line.
  • the central module can include a condenser in which the liquid is recovered so that it can be used by the central module for a further conveying process.
  • the first branch via which the pressure source is connected to the return line, can be arranged between the evaporation chamber and the overflow valve.
  • a first check valve can be arranged between the first branch and the pressure source in order to prevent the pressure from escaping from the pressure source when the second check valve is open. The first check valve can be controlled so that it is in a closed state when the second check valve is open.
  • the plastic injection molding machine can include a control unit.
  • the control unit can be designed to control the interaction of the components during a work cycle of the plastic injection molding machine.
  • the control unit can give control signals that trigger one or more of the following steps. The steps can be performed in the order shown below or in a different order.
  • the control unit can control an actuator with which the injection mold is brought into a closed state.
  • the control unit can open a first check valve arranged between the pressure source and the evaporation chamber, so that the evaporation chamber is pressurized from the pressure source.
  • the control unit can control the feed unit so that a plastic material is injected into the cavity of the injection mold in an injection phase.
  • the control unit can control the feed unit so that pressure is exerted on the plastic material in the cavity in a pressing phase following the injection phase.
  • the control unit can control the high-pressure pump so that liquid is continuously pumped into the evaporation chamber in a delivery phase.
  • the control unit can control the central module so that the conveying process is ended before the injection mold is opened.
  • the control unit can control the actuator of the injection molding control so that the injection mold is brought into an open state.
  • the control unit can close the first check valve arranged between the pressure source and the evaporation chamber.
  • the control unit can bring a second check valve bridging the overflow valve into an open state so that the excess pressure in the evaporation chamber can be reduced.
  • the control unit can control the central module so that the evaporation chamber is blown out with a burst of gas.
  • the control unit can control the second check valve so that it closes.
  • the control unit can control the first check valve so that it opens.
  • the control unit can control the injection molding machine so that a work cycle of this type is carried out several times.
  • control unit is a structural unit. It is also possible, for example, for the injection molding process to be controlled with a first control module and the cooling device to be controlled with a second control module. It can be a master-slave configuration in which the first control module is used as a master and the second control module as a slave.
  • the invention also relates to a method for operating a plastic injection molding machine.
  • the plastic injection molding machine comprises an injection mold.
  • the injection mold has a mold core that extends into the cavity of the injection mold and is provided with an evaporation chamber.
  • a plastic material is injected into the cavity using a feed unit.
  • an overpressure is applied from a pressure source.
  • a liquid is conveyed into the evaporation chamber under overpressure.
  • a pressure increase in the evaporation chamber resulting from the conveying process and from evaporation of the liquid is Overflow valve whose opening pressure is higher than the overpressure applied in the evaporation chamber.
  • the pressure in the evaporation chamber can be applied while a valve arranged between the pressure source and the evaporation chamber is open.
  • the pressure in the evaporation chamber can be reduced while the valve is closed.
  • the disclosure includes developments of the method with features that are described in connection with the plastic injection molding machine according to the invention.
  • the disclosure includes further developments of the plastic injection molding machine, which are described in the context of the method according to the invention.
  • Fig. 1 a schematic representation of an injection molding machine according to the invention
  • Fig. 2 the mold core of the injection molding machine from Fig. 1 in an enlarged view
  • Fig. 3 a representation of the pressure source from Fig. 1;
  • Fig. 4-7 further details of the injection molding machine from Fig.
  • An injection molding machine shown in Fig. 1 comprises a frame 14 which carries an injection mold 15 consisting of two mold halves 11, 12.
  • the injection mold 15 is shown in the open state.
  • the two mold halves 11, 12 are moved towards each other, so that a completely closed cavity 16 is formed inside the injection mold 15.
  • a mold core 18 connected to the first mold half 11 protrudes into it.
  • the injection molding machine includes actuators (not shown) with which one or both mold halves 11, 12 can be moved in a suitable manner relative to the frame 14.
  • a piston screw 13 of a feed unit 17 is started to inject a plastic material in a liquid state into the interior of the injection mold 15, so that the cavity 16 is completely filled with the plastic material.
  • the piston screw maintains the pressure acting on the plastic material until the plastic material has hardened in an area 40 between the feed unit 17 and the cavity 16.
  • the plastic material in the cavity 16 hardens completely without any external pressure being exerted.
  • the injection mold 15 is opened. An injection molded part whose shape corresponds to the cavity 16 is removed from the injection mold 15 .
  • the injection molded part has a recess that corresponds to the mold core 18.
  • heat is specifically removed from the plastic material in the vicinity of the mold core 18 during curing.
  • a blind hole is formed in the interior of the mold core 18, which extends almost to the distal end of the mold core 18, see FIG. 2.
  • the end of the bore forms an evaporation chamber 28 arranged inside the mold core 18.
  • a capillary tube 30 extends in the center of the bore, at the distal end of which an outlet opening 43 opening into the evaporation chamber 28 is formed.
  • a proximal end of the capillary tube 30 is connected to a supply line 32.
  • An annular return channel is formed between the capillary tube 30 and the wall 29 of the mold core 18 and is connected to a return line 33 .
  • the supply line 32 and the return line 33 are connected to a central module 19, which, together with the evaporation chamber 28 and other components, forms a cooling device for the injection molding machine.
  • the central module 19 includes a high-pressure pump 42 which is connected to the other end of the supply line 32.
  • the high-pressure pump 42 is designed to deliver water in the direction of the capillary tube 30 in a delivery phase under a high pressure, which can be, for example, 20 bar higher than atmospheric pressure.
  • the water emerges as a fine jet from the outlet opening 43 of the capillary tube 30 and is distributed in the evaporation chamber 28.
  • the temperature in the evaporation chamber 28 and in the distal region of the annular return channel is so high that the liquid evaporates.
  • the evaporation process removes heat from the plastic material in the vicinity of the mold core 18.
  • a pressure source 27 is connected to a branch 45 in the return line 33 via an adjustable pressure reducer 26 and a first valve combination 25.
  • the first valve combination 25 comprises, according to FIG. 3 a check valve 34 and a switchable check valve 35, which in the open state provides a free passage between the return line 33 and the check valve 34 and which closes the passage when closed.
  • the pressure source 27 which can be, for example, a pressure reservoir or a pressurized line
  • a pressure PI which is reduced to a lower pressure P2 by the adjustable pressure reducer 26.
  • the shut-off valve 35 When the shut-off valve 35 is open, the pressure P2 set by the pressure reducer 26 spreads via the return line 33 to the evaporation chamber 28, provided that the pressure in the return line 33 and the evaporation chamber 28 is lower than the pressure P2. Conversely, if the pressure in the return line 33 is higher than the pressure P2 set by the pressure reducer 26, the check valve 34 closes and no pressure equalization takes place.
  • the pressure P2 spreads into the evaporation chamber 28. If the hardening of the plastic material begins after the plastic material has been injected into the cavity 16 of the injection mold 18, this is accompanied by active cooling by pumping water into the evaporation chamber with the high-pressure pump 42.
  • the pressure P2 is set so that the conveying phase can extend without interruption over the entire duration of the hardening, i.e. from the beginning of the pressing phase to the end of the residual cooling phase, without the structure of the plastic material being damaged by excessive cooling.
  • a second valve combination 24 is arranged in the return line 33 and is shown in FIG. 4 includes an overflow valve 36 and a switchable check valve 37 connected in parallel thereto. The check valve 37 is closed.
  • the overflow valve 36 has an opening pressure that is slightly higher than the pressure P2 specified by the pressure reducer 26, so that the overflow valve 36 opens quickly when the pressure increases from the evaporation chamber 28. Even during the delivery phase, the pressure in the evaporation chamber 28 therefore does not increase significantly.
  • the second shut-off valve 37 is opened and the first shut-off valve 35 is closed so that pressure equalization to atmospheric pressure takes place via the return line 33.
  • the water-gas mixture is led from the evaporation chamber back to the central module 19. Water components contained in the mixture are condensed in the central module 19 and can be used again in a subsequent delivery phase.
  • the supply line 32 arranged between the central module 19 and the evaporation chamber 18 comprises a branch 46 to which a compressed air line 22 is connected. After the pressure has equalized to atmospheric pressure in the evaporation chamber 28, a burst of compressed air can be passed from the central module 19 into the compressed air line 22, which spreads through the capillary tube 33 to the evaporation chamber 28, so that any remaining liquid there is blown out through the return line 33. In this way, defined initial conditions can be created for the subsequent work cycle of the injection molding machine, if desired.
  • a second check valve 38 is arranged in the supply line 32, so that the compressed air blast from the compressed air line 22 cannot spread in the direction of the central module 19, see FIG. 6.
  • a third check valve 39 is arranged in the compressed air line 22 in order to prevent an undesirable backflow in the direction of the central module 19 in the delivery phase, see FIG. 7.
  • a fourth check valve 21 is arranged in the supply line 32 adjacent to the mold core 18, see FIG. 5.
  • the fourth check valve 21 becomes effective when the pressure equalization between the pressure P2 of the pressure reducer and the evaporation chamber 28 is carried out at the beginning of a work cycle of the injection molding machine.
  • the pressure P2 which is increased compared to atmospheric pressure, only spreads to the fourth check valve 21. In this way, the liquid can penetrate more easily to the evaporation chamber 28 in the subsequent delivery phase.
  • the injection molding machine includes a control unit 41 that controls the interaction of the components.
  • the injection mold 15 is closed and the first check valve 35 is opened, so that the pressure in the evaporation chamber increases from atmospheric pressure to the pressure P2 specified by the pressure reducer 26.
  • the feed unit 17 is activated to fill the cavity 16 of the injection mold 15 with plastic material. The pressure exerted by the feed unit 17 is maintained during the subsequent pressing phase.
  • the high-pressure pump 42 is activated so that water is conveyed into the evaporation chamber 28 during the post-pressure phase and the subsequent residual cooling phase. At the end of the residual cooling phase, the high-pressure pump 42 is deactivated.
  • the injection mold 15 is opened so that the injection molded part can be removed. Parallel the first check valve 35 is closed and the second
  • Check valve 37 is opened in order to equalize the pressure in the evaporation chamber 28 to atmospheric pressure via the central module 19. With a blast of compressed air emitted by the central module 19, defined initial conditions are created for the subsequent work cycle of the injection molding machine.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Oral & Maxillofacial Surgery (AREA)
  • Thermal Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Injection Moulding Of Plastics Or The Like (AREA)

Abstract

L'invention concerne une machine de moulage par injection de matière plastique comportant un moule de moulage par injection (15), une unité d'alimentation (17), destinée à injecter une matière plastique dans une cavité (16) du moule de moulage par injection (15) et un dispositif de refroidissement (19, 24, 28, 32, 33) pour le moule de moulage par injection (15). Le moule de moulage par injection (15) présente un noyau de moule (18) faisant saillie dans la cavité (16) et muni d'une chambre d'évaporation (28). Une source de pression (26, 27), destinée à produire une surpression dans la chambre de vaporisation (28), est raccordée à la chambre de vaporisation (28). Le dispositif de refroidissement (19, 24, 28, 32, 33) comprend une pompe haute pression (30, 42) disposée en amont de la chambre de vaporisation (28) et destinée à refouler un liquide dans la chambre de vaporisation (28) et une soupape de trop-plein (36) disposée en aval de la chambre de vaporisation (28) et dont la pression d'ouverture est supérieure à la pression produite par la source de pression (26, 27). Un embranchement (45), auquel la source de pression (26, 27) est raccordée, est réalisé entre la chambre de vaporisation (28) et la soupape de trop-plein (36) Une soupape (34, 35), qui est ouverte dans un premier état et fermée dans un second état, est disposée entre l'embranchement (45) et la source de pression (26, 27). L'invention concerne par ailleurs un procédé permettant de faire fonctionner une machine de moulage par injection.
PCT/EP2023/076958 2022-09-29 2023-09-28 Machine de moulage par injection de matière plastique et procédé permettant de faire fonctionner une machine de moulage par injection de matière plastique WO2024068874A1 (fr)

Applications Claiming Priority (2)

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EP22198623 2022-09-29
EP22198623.5 2022-09-29

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WO2024068874A1 true WO2024068874A1 (fr) 2024-04-04

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PCT/EP2023/076958 WO2024068874A1 (fr) 2022-09-29 2023-09-28 Machine de moulage par injection de matière plastique et procédé permettant de faire fonctionner une machine de moulage par injection de matière plastique

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05220562A (ja) * 1992-02-12 1993-08-31 Ryobi Ltd 金型冷却装置
WO2019158521A1 (fr) 2018-02-13 2019-08-22 G.A. Röders Holding Gmbh & Co. Kg Dispositif et procédé de refroidissement d'un moule

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05220562A (ja) * 1992-02-12 1993-08-31 Ryobi Ltd 金型冷却装置
WO2019158521A1 (fr) 2018-02-13 2019-08-22 G.A. Röders Holding Gmbh & Co. Kg Dispositif et procédé de refroidissement d'un moule

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