WO1997027988A1 - An injection moulding process - Google Patents

An injection moulding process Download PDF

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Publication number
WO1997027988A1
WO1997027988A1 PCT/SE1997/000141 SE9700141W WO9727988A1 WO 1997027988 A1 WO1997027988 A1 WO 1997027988A1 SE 9700141 W SE9700141 W SE 9700141W WO 9727988 A1 WO9727988 A1 WO 9727988A1
Authority
WO
WIPO (PCT)
Prior art keywords
cooling body
heating
inlet nozzle
molten
cooling
Prior art date
Application number
PCT/SE1997/000141
Other languages
French (fr)
Inventor
Owe Larsson
Original Assignee
Aga Aktiebolag
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 Aga Aktiebolag filed Critical Aga Aktiebolag
Priority to AU16798/97A priority Critical patent/AU1679897A/en
Publication of WO1997027988A1 publication Critical patent/WO1997027988A1/en

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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
    • B22D17/22—Dies; Die plates; Die supports; Cooling equipment for dies; Accessories for loosening and ejecting castings from dies
    • B22D17/2272—Sprue channels
    • B22D17/2281—Sprue channels closure devices therefor
    • 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
    • B22D17/2023—Nozzles or shot sleeves
    • 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
    • B29C45/2737—Heating or cooling 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
    • B29C45/2737—Heating or cooling means therefor
    • B29C2045/2753—Heating means and cooling means, e.g. heating the runner nozzle and cooling the nozzle tip
    • 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
    • B29C45/2737—Heating or cooling means therefor
    • B29C2045/2754—Plurality of independent heating or cooling means, e.g. independently controlling the heating of several zones of the nozzle
    • 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
    • B29C45/30—Flow control means disposed within the sprue channel, e.g. "torpedo" construction

Definitions

  • the present invention relates to a process in an injection moulding procedure
  • Injection moulding is a well known and cost effective way to manufacture products of thermoplastic material This method is also utilised for manufacturing moulded products of metals with a low melting temperature In both cases the material is brought to a melt wherafter the material is injected into a mould cavity, which defines the shape of the detail The material is then cooled until it becomes solid, whereupon the mould can be opened and the detail produced can be removed
  • the molten material was, in the early versions of injection moulding, injected through a channel, often called stalk or sprue This sprue caused an unwanted rod ⁇ like remainder on the detail when this were ejected from the mould This sprue was manually removed, which was a disadvantage
  • One advantage was however, especially at the injection moulding of a thermoplastic material, that slag-like accumulations and stressing of the material were avoided Slag-like accumulations will often give shadow-like discolourations in the product, while material stress will cause decomposing of the polymer chains in thermoplastic materials This will cause lower impact strength and a lower elasticity modulus in the product
  • the inlet channel is provided with heating elements, this is most often called a hot runner
  • the thermoplastic material in the hot runner will be kept in a molten state w hile the plastic in the mould cavity becomes solid
  • the heating elements can either be placed around the channel, like a cylinder, or inside the channel like a rod, often called a torpedo, where the plastic material surrounds the heater
  • the physical apperence of this system can be compared with a bottle without a bottom where the neck is connected to the detail, or actually the mould cavity This will howevei cause friction heat which will be formed in the narrow injection nozzle due to the very high flow velocity This friction heat will cause decomposing of the polymer chains
  • Another type of injection system also includes a so-called needle valve gate placed adjacent to the mould cavity This needle valve gate is closed by sliding the needle towards the mould cavity when the desired amount of molten thermoplastic material has been injected.
  • this method causes friction heat Slag accumulations will in both cases be formed on the surfaces of the iniection system which are overheated by friction heat. These slag accumulations will gradually come loose and follow the material stream into the detail. The slag causes dark discolourations and will also give local weakenings
  • the needle in the needle valve will additionally cause turbulence in the molten material. This turbulence will propagate into the mould cavity and will cause so-called flow lines in the detail. Further on, the heat accumulated in the needle heats the needle seat and the material which is supposed to solidify in the mould cavity This is one of the reasons for the characteristic irregularities that often can be found around the injection point of an injection moulded plastic product
  • the above mentioned problems have been solved through the present invention, wherein injection moulded products with a considerable reduction of discolouration and a reduction of the risk of decomposition can be achieved, without need for post treatment.
  • the invention relates to a process in an injection moulding procedure assisted by a hot runner system where a molten thermoplastic material or a molten metal is injected through the hot runner system and an inlet nozzle.
  • the invention is characterised in that the inlet nozzle is placed at the end of the hot runner system and includes a micro-porous cooling body which preferably is ring or cylinder shaped, and channels for communicating a cooling agent from a supply source to the cooling body
  • a micro-porous cooling body which preferably is ring or cylinder shaped, and channels for communicating a cooling agent from a supply source to the cooling body
  • a predetermined amount of molten thermoplastic material or molten metal is allowed to flow through the hot runner system, and the inlet nozzle, into the mould cavity of the mould where the thermoplastic material or molten metal begins to solidify.
  • the cooling agent is allowed to flow through the channels and into the cooling body.
  • the cooling body is thereby cooled and cools in its turn the molten thermoplastic material or the molten metal surrounded by the cooling body.
  • the molten material will thereby solidify into a plug which stops further communication of molten thermoplastic material or metal through the inlet nozzle while the thermoplastic material or metal is allow ed to solidify in the mould cavity.
  • the mould can then be opened, the detail can be removed, and the procedure can be repeted
  • the hot runner system can, when needed, be designed so that its heat content can be used to melt the plug. This is suitably achieved by providing the hot runner with a heat conducting sleeve placed between the flowpath of the molten material and the cooling body. The plug will hereby melt as soon as the supply of cooling agent is discontinued. This can be co-ordinated with the opening of the mould so that the plug will be molten before the next injection moulding procedure is initiated.
  • the surface of the micro-porous cooling body is suitably sealed, at least on the surfaces being in contact with the molten material. The cooling agent is thereby prevented from entering, and mixing with, the molten material .
  • the cooling body can alternatively be placed inside the hot runner so that it is surrounded by the molten material
  • the cooling body is then suitably given a streamlined design and supported by two or more legs which are connected to the outer walls of the hot runner.
  • the legs are suitably provided with channels for communication of the cooling agent .
  • the surface of the cooling body is suitably sealed so that the cooling agent doesn't mix with the molten material.
  • a heating device is placed in connection with the inlet nozzle.
  • the heating device is used to heat the plug This can thereby be heated so that it partially or completely melts before the opening of the mould and the removal of the detail produced and/or before the injection of the molten thermoplastic material or metal in the next moulding procedure
  • the size of the inlet residue can thereby be controlled by controlling the amount of heat added and the heating time so that the desired results are achieved
  • the injection residue can hereby be given an almost insignificant size without any need for post treatment.
  • a temperature sensor is used, which then is placed in connection to the cooling body.
  • the supply of cooling agent and/or heating energy to the inlet nozzle can be controlled by means of the temperature sensor, during the whole of, or parts of the moulding procedure.
  • the temperature in the inlet nozzle can thereby be adjusted to the different levels suitable to each of the different steps in the injection moulding process.
  • Electric energy is preferably utilised for supplying the heating device.
  • at least one, preferably two or three separate rod shaped heating elements are used as a heating device The points of these elements are directed towards the inlet nozzle.
  • a ring-shaped heating element which is placed adjacent to the cooling body, preferably between the mould cavity and the cooling body, is used as a heating device.
  • a heat insulating layer is suitably placed between the heating device and the mould cavity so that the material therein is not heated unintentionally.
  • a valve array is suitably used, which valve array is connected to the channels which are communicating with the cooling body
  • the cooling body can, besides the connection to the cooling agent, also be connected to a heating agent by switching the valve arrray between two supply sources
  • cooling agent and heating agent suitably a gas is used .
  • the gas can suitablv be selected from the group carbon dioxide, hydrogen, air, argon, helium, nitrogen or mixtures of two or more thereof
  • a heating chamber is used , which is placed between the valve array and the supply source
  • FIG. 1 shows in cross section one embodiment of the process according to the invention
  • the illustrated process comprises an injection moulding procedure by means of a hot runner system 1 where molten thermoplastic mate ⁇ al 2' is miected through an inlet nozzle 3
  • the inlet nozzle 3 is placed at the end of the hot runner and includes a micro-porous cooling body 4 and channels 5 for communicating a cooling agent from a supply source 6 to the cooling body 4
  • a predermined amount of molten thermoplastic mate ⁇ al is allowed to pass through the hot runner
  • thermoplastic material begins to solidify
  • a cooling agent is allowed to flow through the cooling body 4 via the channels 5
  • the cooling body 4 will thereby be cooled, and then, in its turn cool the thermoplastic mate ⁇ al that it surrounds, so that the molten plastic mate ⁇ al will solidifv into a plug 10 w hich stops further communication of molten thermoplastic material through the inlet nozzle 3
  • the plastic mate ⁇ al in the mould cavitv 8 is meanw hile allowed to become solid whereupon the mould is opened so that the detail can be removed and the moulding procedure can be repeted
  • a temperature sensor 1 1 placed adjacent to the cooling body 4 is used for controlling the suppl of cooling and heating agent to the cooling body 4
  • the temperature in the inlet nozzle 3 can hereby, du ⁇ ng the whole process, be adapted to the different levels suitable for each step in the process
  • a ring shaped heating element 9" is placed adiacent to the cooling body 4
  • the process according to the invention can also be used for injection moulding of metal products, where the metal has a low melting temperature, preferably below 600°C
  • suitable metals tin, lead, zink and magnesium can be mentioned Also alloys with aluminium, tin, lead, zink and magnesium can be used
  • the process according to the invention can also be used for injection moulding of composites where a thermoplastic material binds metal granules Thermoplastic coated metal granules are here injected into the mould cavity
  • the cooling of the cooling body is suitably achieved by letting a gas under pressure flow into the cooling body where it is allowed to expand
  • the gas is suitably pressurised so that it enters a liquid state, which for example can be done within a resonable temperature intervall with carbon dioxide
  • the gas will when expanding, due to its relative energy content, cool the the cooling body
  • the energy absorbed by the gas will be conveyed by the gas percolation
  • the process illustrated in figure 2 corresponds in the main to the process described together with figure 1 .
  • two rod shaped heating elements 9' are placed adjacent to the cooling body 4
  • the point of the rod shaped elements are directed towards the inlet nozzle 3
  • the heating elements 9' are used for melting the plastic plug 1 0 at the end of each moulding cycle
  • the mould is opened and the completed detail can be removed when the plastic plug 10 is partly melted
  • the plastic plug 10, or the remainder of the plastic plug 10 is then allowed to melt completely before the mould cavity, after closure, again can be filled with melted thermoplastic material injected through inlet nozzle 3
  • the process illustated in figure 3 corresponds in the main to the process described together with figure 1
  • the hot runner 1 has however been provided with a heat conducting sleeve 1 ', which conveys heat from the hot runner 1 so that the plastic plug 10 can melt when the supply of cooling agent to the cooling body 4 is discontinued Then additional heat energy from any other source, other than the one already existing in the hot runner 1 , will not be necessary
  • the invention is not limited to the embodiments shown since they can be varied in different ways within the scoop of the invention
  • the cooling body 4 can for example, through alternating connection between a cooling agent and a heating agent, as described together with figure 1 , completely replace the function of the heating elements 9' and 9"
  • the rod shaped heating elements 9' illustrated in figure 2 can also be replaced by the ring shaped heating element 9" illustrated in figure 1 , in the process described together with figure 2

Abstract

A process in an injection moulding procedure where molten thermoplastic material (2') or molten metal (2'') is injected through a hot runner system (1) and an inlet nozzle (3). The inlet nozzle (3) includes a micro-porous cooling body (4). Channels (5) are provided for communicating a cooling agent from a supply source (6) to the cooling body (4). Molten material is allowed to flow through the hot runner system (1), the inlet nozzle (3) and into a mould cavity (8). The molten material begins to solidify, whereupon the cooling agent flows through the channels (5) and into the cooling body (4). The cooling body (4) hereby cools the molten material surrounded by the cooling body (4). The molten material thereby solidifies into a plug (10) which stops further communication of molten material through the inlet nozzle (3) while the material is allowed to solidify in the mould cavity (8). The mould (7) can thereafter be opened, the detail produced can be removed, and the procedure can be repeated.

Description

An iniection moulding process
The present invention relates to a process in an injection moulding procedure
Injection moulding is a well known and cost effective way to manufacture products of thermoplastic material This method is also utilised for manufacturing moulded products of metals with a low melting temperature In both cases the material is brought to a melt wherafter the material is injected into a mould cavity, which defines the shape of the detail The material is then cooled until it becomes solid, whereupon the mould can be opened and the detail produced can be removed
The molten material was, in the early versions of injection moulding, injected through a channel, often called stalk or sprue This sprue caused an unwanted rod¬ like remainder on the detail when this were ejected from the mould This sprue was manually removed, which was a disadvantage One advantage was however, especially at the injection moulding of a thermoplastic material, that slag-like accumulations and stressing of the material were avoided Slag-like accumulations will often give shadow-like discolourations in the product, while material stress will cause decomposing of the polymer chains in thermoplastic materials This will cause lower impact strength and a lower elasticity modulus in the product
The post treatement procedures were however regarded as so costly that new injection systems were developed In one type of injection system the inlet channel is provided with heating elements, this is most often called a hot runner The thermoplastic material in the hot runner will be kept in a molten state w hile the plastic in the mould cavity becomes solid The heating elements can either be placed around the channel, like a cylinder, or inside the channel like a rod, often called a torpedo, where the plastic material surrounds the heater The physical apperence of this system can be compared with a bottle without a bottom where the neck is connected to the detail, or actually the mould cavity This will howevei cause friction heat which will be formed in the narrow injection nozzle due to the very high flow velocity This friction heat will cause decomposing of the polymer chains
Another type of injection system also includes a so-called needle valve gate placed adjacent to the mould cavity This needle valve gate is closed by sliding the needle towards the mould cavity when the desired amount of molten thermoplastic material has been injected Also this method causes friction heat Slag accumulations will in both cases be formed on the surfaces of the iniection system which are overheated by friction heat. These slag accumulations will gradually come loose and follow the material stream into the detail. The slag causes dark discolourations and will also give local weakenings The needle in the needle valve will additionally cause turbulence in the molten material. This turbulence will propagate into the mould cavity and will cause so-called flow lines in the detail. Further on, the heat accumulated in the needle heats the needle seat and the material which is supposed to solidify in the mould cavity This is one of the reasons for the characteristic irregularities that often can be found around the injection point of an injection moulded plastic product
The above mentioned problems have been solved through the present invention, wherein injection moulded products with a considerable reduction of discolouration and a reduction of the risk of decomposition can be achieved, without need for post treatment. The invention relates to a process in an injection moulding procedure assisted by a hot runner system where a molten thermoplastic material or a molten metal is injected through the hot runner system and an inlet nozzle. The invention is characterised in that the inlet nozzle is placed at the end of the hot runner system and includes a micro-porous cooling body which preferably is ring or cylinder shaped, and channels for communicating a cooling agent from a supply source to the cooling body A predetermined amount of molten thermoplastic material or molten metal is allowed to flow through the hot runner system, and the inlet nozzle, into the mould cavity of the mould where the thermoplastic material or molten metal begins to solidify. At a predetermined time in the injection moulding process the cooling agent is allowed to flow through the channels and into the cooling body. The cooling body is thereby cooled and cools in its turn the molten thermoplastic material or the molten metal surrounded by the cooling body. The molten material will thereby solidify into a plug which stops further communication of molten thermoplastic material or metal through the inlet nozzle while the thermoplastic material or metal is allow ed to solidify in the mould cavity. The mould can then be opened, the detail can be removed, and the procedure can be repeted
The hot runner system can, when needed, be designed so that its heat content can be used to melt the plug. This is suitably achieved by providing the hot runner with a heat conducting sleeve placed between the flowpath of the molten material and the cooling body. The plug will hereby melt as soon as the supply of cooling agent is discontinued. This can be co-ordinated with the opening of the mould so that the plug will be molten before the next injection moulding procedure is initiated. The surface of the micro-porous cooling body is suitably sealed, at least on the surfaces being in contact with the molten material. The cooling agent is thereby prevented from entering, and mixing with, the molten material .
The cooling body can alternatively be placed inside the hot runner so that it is surrounded by the molten material The cooling body is then suitably given a streamlined design and supported by two or more legs which are connected to the outer walls of the hot runner. The legs are suitably provided with channels for communication of the cooling agent . The surface of the cooling body is suitably sealed so that the cooling agent doesn't mix with the molten material.
Preferably a heating device is placed in connection with the inlet nozzle. The heating device is used to heat the plug This can thereby be heated so that it partially or completely melts before the opening of the mould and the removal of the detail produced and/or before the injection of the molten thermoplastic material or metal in the next moulding procedure The size of the inlet residue can thereby be controlled by controlling the amount of heat added and the heating time so that the desired results are achieved The injection residue can hereby be given an almost insignificant size without any need for post treatment.
Suitably a temperature sensor is used, which then is placed in connection to the cooling body. The supply of cooling agent and/or heating energy to the inlet nozzle can be controlled by means of the temperature sensor, during the whole of, or parts of the moulding procedure. The temperature in the inlet nozzle can thereby be adjusted to the different levels suitable to each of the different steps in the injection moulding process.
Electric energy is preferably utilised for supplying the heating device. According to one embodiment of the invention at least one, preferably two or three separate rod shaped heating elements are used as a heating device The points of these elements are directed towards the inlet nozzle. According to another embodiment of the invention a ring-shaped heating element, which is placed adjacent to the cooling body, preferably between the mould cavity and the cooling body, is used as a heating device. A heat insulating layer is suitably placed between the heating device and the mould cavity so that the material therein is not heated unintentionally.
A valve array is suitably used, which valve array is connected to the channels which are communicating with the cooling body The cooling body can, besides the connection to the cooling agent, also be connected to a heating agent by switching the valve arrray between two supply sources As cooling agent and heating agent suitably a gas is used . The gas can suitablv be selected from the group carbon dioxide, hydrogen, air, argon, helium, nitrogen or mixtures of two or more thereof
When a gas is to be used as a heating agent, suitably a heating chamber is used, which is placed between the valve array and the supply source
The invention is further explained in connection to the enclosed figures which show different embodiments of the invention wherein,
-Figure 1 schematically, in cross section, shows a part of a mold where molten thermoplastic mateπal has been injected and a plug just has become solid
-Figure 2 schematically, in cross section, shows another embodiment of the inv ention where molten thermoplastic material has been injected and a plug |ust has become solid
-Figure 3 schematically, in cross section, shows yet another embodiment of the invention where molten thermoplastic mateπal has been injected and a plug just has become solid
Figure 1 shows in cross section one embodiment of the process according to the invention The illustrated process comprises an injection moulding procedure by means of a hot runner system 1 where molten thermoplastic mateπal 2' is miected through an inlet nozzle 3 The inlet nozzle 3 is placed at the end of the hot runner and includes a micro-porous cooling body 4 and channels 5 for communicating a cooling agent from a supply source 6 to the cooling body 4 A predermined amount of molten thermoplastic mateπal is allowed to pass through the hot runner
1 and the inlet nozzle 3 into a mould cavity 8 where the molten thermoplastic material begins to solidify At a predetermined time in the process a cooling agent is allowed to flow through the cooling body 4 via the channels 5 The cooling body 4 will thereby be cooled, and then, in its turn cool the thermoplastic mateπal that it surrounds, so that the molten plastic mateπal will solidifv into a plug 10 w hich stops further communication of molten thermoplastic material through the inlet nozzle 3 The plastic mateπal in the mould cavitv 8 is meanw hile allowed to become solid whereupon the mould is opened so that the detail can be removed and the moulding procedure can be repeted A temperature sensor 1 1 , placed adjacent to the cooling body 4 is used for controlling the suppl of cooling and heating agent to the cooling body 4 The temperature in the inlet nozzle 3 can hereby, duπng the whole process, be adapted to the different levels suitable for each step in the process A ring shaped heating element 9" is placed adiacent to the cooling body 4 The heating element 9" is utilised for heating the part of the plastic plug 10 placed closest to the surface before opening of the mould A valve array 12 is connected to the channels 5 , so that the cooling body 4, besides the connection with cooling agent, also alternately can be connected to a heating agent by letting the valve array alternate between its two supply sources 6' and 6" A heating chamber 1 3 is placed between the valve array 12 and the supply source 6" The heating chamber heats the gas used as a heating agent The remainder of the plug 10 is thereby melted before starting the injection of melted thermoplastic material in the next moulding cycle
The process according to the invention can also be used for injection moulding of metal products, where the metal has a low melting temperature, preferably below 600°C As an example of suitable metals tin, lead, zink and magnesium can be mentioned Also alloys with aluminium, tin, lead, zink and magnesium can be used The process according to the invention can also be used for injection moulding of composites where a thermoplastic material binds metal granules Thermoplastic coated metal granules are here injected into the mould cavity
The cooling of the cooling body is suitably achieved by letting a gas under pressure flow into the cooling body where it is allowed to expand The gas is suitably pressurised so that it enters a liquid state, which for example can be done within a resonable temperature intervall with carbon dioxide The gas will when expanding, due to its relative energy content, cool the the cooling body The energy absorbed by the gas will be conveyed by the gas percolation
The process illustrated in figure 2 corresponds in the main to the process described together with figure 1 . In the process according to figure 2 however two rod shaped heating elements 9' are placed adjacent to the cooling body 4 The point of the rod shaped elements are directed towards the inlet nozzle 3 The heating elements 9' are used for melting the plastic plug 1 0 at the end of each moulding cycle The mould is opened and the completed detail can be removed when the plastic plug 10 is partly melted The plastic plug 10, or the remainder of the plastic plug 10, is then allowed to melt completely before the mould cavity, after closure, again can be filled with melted thermoplastic material injected through inlet nozzle 3
The process illustated in figure 3 corresponds in the main to the process described together with figure 1 The hot runner 1 has however been provided with a heat conducting sleeve 1 ', which conveys heat from the hot runner 1 so that the plastic plug 10 can melt when the supply of cooling agent to the cooling body 4 is discontinued Then additional heat energy from any other source, other than the one already existing in the hot runner 1 , will not be necessary
The invention is not limited to the embodiments shown since they can be varied in different ways within the scoop of the invention The cooling body 4 can for example, through alternating connection between a cooling agent and a heating agent, as described together with figure 1 , completely replace the function of the heating elements 9' and 9" The rod shaped heating elements 9' illustrated in figure 2, can also be replaced by the ring shaped heating element 9" illustrated in figure 1 , in the process described together with figure 2

Claims

1 . A process in an injection moulding procedure assisted by a hot runner system ( 1 ) where a molten thermoplastic material (2') or a molten metal (2") is injected through the hot runner system ( 1 ) and an inlet nozzle (3), characterised in that the inlet nozzle (3) is placed at the end of the hot runner system ( 1 ) and includes a micro-porous cooling body (4) which preferably is ring or cylinder shaped, and channels (5) for communicating a cooling agent from a supply source (6) to the cooling body (4), wherein a predetermined amount of molten thermoplastic material or molten metal respectively is allowed to flow through the hot runner system ( 1 ) and the inlet nozzle (3) and into a mould cavity (8) of a mould (7) where the thermoplastic material or molten metal respectively begins to solidify, whereupon a cooling agent is allowed to flow through the channels (5) and into the cooling body (4) at a predetermined time in the injection moulding process, at which the cooling body (4) is cooled and in its turn cools the molten thermoplastic material or the molten metal surrounded by the cooling body (4), which molten material thereby solidifies into a plug ( 10) which stops further communication of molten thermoplastic material or molten metal through the inlet nozzle (3) while the melt of thermoplastic material or metal is allowed to solidify in the mould cavity (8), whereupon the mould (7) can be opened, the detail can be removed, and the procedure can be repeted
2. A process according to claim 1 characterised in that a heating device (9), which is placed in connection to the inlet nozzle (3), is used for heating the plug ( 10) whereby the plug ( 10) can be heated so that it partially or completely melts before the opening of the mould and removal of the finished detail and/or before the injection of the molten thermoplastic material or metal in the next moulding procedure.
3. A process according to claim 1 or 2 characterised in that a temperature sensor ( 1 1 ), is placed in connection to the cooling body (4) whereby the supply of cooling agent and/or heating energy to the inlet nozzle (3) can be controlled by means of the temperature sensor ( 1 1 ) so that the temperature in the inlet nozzle (3) can be adjusted to levels suitable to the different steps in the injection moulding process
4 A process according to claim 2 or 3 characterised in that electric energy is utilised for supplying the heating device (9) . A process according to claim 4 characterised in that at least one, preferably two or three separate rod shaped heating elements (9') of which the point are directed towards the inlet nozzle (3 ), are used as a heating device (9)
A process according to claim 4 characterised in that a ring-shaped heating element (9"), which is placed adjacent to the cooling body (4), preferably between the mould cavity (8) and the cooling body (4), is used as a heating device (9)
A process according to claim 1 characterised in that a valve array ( 12) is connected to the channels (5) communaicating with the cooling device (4), whereby the cooling body (4) besides the connection to the cooling agent also can be connected to a heating agent by switching the valve arrray ( 1 2) between two supply sources (6' and 6")
A process according to any of the previous claims characterised in that a gas is used as a cooling agent or a heating agent respectively A process according to claim 8 characterised in that a heating chamber ( 13 ) is placed between the valve array ( 12) and the supply source (6"), which heating chamber ( 13) is used for heating the gas utilised as a heating agent
PCT/SE1997/000141 1996-02-01 1997-01-29 An injection moulding process WO1997027988A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU16798/97A AU1679897A (en) 1996-02-01 1997-01-29 An injection moulding process

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9600374A SE506043C2 (en) 1996-02-01 1996-02-01 Injection molding process
SE9600374-4 1996-02-01

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0978364A2 (en) * 1998-08-06 2000-02-09 Franz Sterner Injector nozzle for an injection mould
EP1389517A1 (en) * 2002-08-16 2004-02-18 Yudo Co., Ltd. Shut-off nozzle with heating unit and cooling unit for hot runner systems of injection molding machines, and method of controlling the same
WO2007028265A2 (en) * 2005-09-08 2007-03-15 Bühler Druckguss AG Diecasting method
WO2007095719A1 (en) * 2006-02-24 2007-08-30 Husky Injection Molding Systems Ltd. Metallic-molding-material runner having equilibrated flow
WO2008095280A1 (en) * 2007-02-08 2008-08-14 Husky Injection Molding Systems Ltd. Identifying quality of molded article based on determination of plug blow
EP1976654A1 (en) * 2005-12-09 2008-10-08 Husky Injection Molding Systems S.A. Thixo-molding shot located downstream of blockage
DE102015224414A1 (en) 2015-12-07 2017-06-08 Volkswagen Aktiengesellschaft cast device

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1992015439A1 (en) * 1991-03-05 1992-09-17 Toolvac Engineering Ab Method for tempering a moulding tool
US5443381A (en) * 1994-07-18 1995-08-22 Gellert; Jobst U. Injection molding one-piece insert having cooling chamber with radial rib portions

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1992015439A1 (en) * 1991-03-05 1992-09-17 Toolvac Engineering Ab Method for tempering a moulding tool
US5443381A (en) * 1994-07-18 1995-08-22 Gellert; Jobst U. Injection molding one-piece insert having cooling chamber with radial rib portions

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0978364A2 (en) * 1998-08-06 2000-02-09 Franz Sterner Injector nozzle for an injection mould
EP0978364A3 (en) * 1998-08-06 2000-09-20 Franz Sterner Injector nozzle for an injection mould
EP1389517A1 (en) * 2002-08-16 2004-02-18 Yudo Co., Ltd. Shut-off nozzle with heating unit and cooling unit for hot runner systems of injection molding machines, and method of controlling the same
WO2007028265A2 (en) * 2005-09-08 2007-03-15 Bühler Druckguss AG Diecasting method
WO2007028265A3 (en) * 2005-09-08 2007-08-02 Buehler Druckguss Ag Diecasting method
EP1976654A1 (en) * 2005-12-09 2008-10-08 Husky Injection Molding Systems S.A. Thixo-molding shot located downstream of blockage
EP1976654A4 (en) * 2005-12-09 2009-03-11 Husky Injection Molding Thixo-molding shot located downstream of blockage
WO2007095719A1 (en) * 2006-02-24 2007-08-30 Husky Injection Molding Systems Ltd. Metallic-molding-material runner having equilibrated flow
US7387154B2 (en) 2006-02-24 2008-06-17 Husky Injection Molding Systems Ltd. Metallic-molding-material runner having equilibrated flow
US7387152B2 (en) * 2006-02-24 2008-06-17 Husky Injection Molding Systems Ltd. Metallic-molding-material runner having equilibrated flow
WO2008095280A1 (en) * 2007-02-08 2008-08-14 Husky Injection Molding Systems Ltd. Identifying quality of molded article based on determination of plug blow
DE102015224414A1 (en) 2015-12-07 2017-06-08 Volkswagen Aktiengesellschaft cast device

Also Published As

Publication number Publication date
SE9600374D0 (en) 1996-02-01
SE506043C2 (en) 1997-11-03
AU1679897A (en) 1997-08-22
SE9600374L (en) 1997-08-02

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