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
  • B29C45/72—Heating or cooling
  • B29C45/73—Heating or cooling of the mould
• • 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

Definitions

• This invention relates to cooling of molds.
• Such molds can include molds of a type useful for molding of materials of a type including injection molding of plastics materials.
• a condensing arrangement positioned above a level of liquid in the chamber in relation to a source of heat within the chamber so as to cool and condense thereby vapour formed as a result of conversion from the liquid from the source of heat.
• a mold which includes an arrangement to assist in controlling of a temperature of the mold including at least one closed chamber within the mold, the chamber being only partially filled with liquid and a remainder of the chamber being filled with substantially only vapour of the liquid within the chamber, at least a portion of the chamber being positioned to transmit heat from a targeted location of the mold into liquid within the chamber, and condensing means by reason of heat exchange to effect condensation of vapour within the chamber, the mold being characterized in that the liquid is arranged, in use, to be distributed in the chamber in such a way that the liquid will be distributed to reach or be held at different heights within the chamber.
• the different heights of liquid are achieved by having at least one reservoir within the chamber with a bottom of the reservoir being above a bottom of the chamber.
• the different heights are achieved by having the liquid being applied as a surface application onto an inner surface of the chamber and above a base level of liquid within the chamber.
• the different heights are achieved by having a passageway with some of the liquid in the passageway where an inlet at least to the passageway is above a base upper level of liquid in the chamber.
• the different heights are achieved by having the liquid selected or having an additive whereby to effect a foaming.
• this is achieved by having a liquid which is adapted to foam during use of the mold.
• a surprising discovery is that in one of the alternative approaches by having the liquid arranged to foam as the liquid is being caused to boil results in the liquid rising as foam containing vapour of the liquid to significantly extend the liquid as a film through the chamber. This then coats the walls of the chamber with liquid.
• the liquid is predominantly water and the foaming agent is a surfactant.
• means to hold some of the liquid in a reservoir which is, therefore, in conjunction with the size and shape of the chamber and the quantity of liquid in the chamber, providing a head of liquid for use for directing a stream or other flow of the liquid through one or more conduits into places which would otherwise be inaccessible to liquid by reason of vapour lock occurring.
• a substantially upright conduit with a lower inlet and an upper outlet and a heat source adjacent a part of such conduit, and a means to hold any liquid lifted through the conduit by boiling of liquid effecting a percolator type effect, at a height above a normally existing upper level of liquid in the chamber.
• foaming agent has the advantage that once boiling occurs anywhere within the liquid, this foam and the water as a film implicit in the foam will readily extend in the manner of foam through the chamber and thereby carry the small amount of water that forms the film forming the foam bubbles with it.
• the physical quantity of water that is carried on the foam can be small. Even smaller quantities of liquid however, in the chamber (which will usually be water), will be sufficient because of the technique being used.
• the maximum height of water within the chamber can be kept very small indeed. (This then forming a base level of liquid within the chamber.)
• Some features of some molds may need some additional assistance in maintaining continuing liquid access for cooling purposes.
• the surface tension of the liquid such as water in relation to the surface of the chamber may impede continuing access of liquid into the conduit shape or in other words a situation where a vapour lock effect may otherwise result.
• a further arrangement for obtaining liquid at a head above the entrance to the conduit is to have a reservoir beneath an area providing for condensing of any vapour within the chamber and then have a conduit extending from such a reservoir down into the injector conduit which has an aperture through which the liquid then will flow at a rate depending upon the head of liquid and the size of the conduit.
• such a reservoir is arranged so as to be a relatively shallow reservoir which will quickly overflow in normal operations so as to return most of the liquid to a lower reservoir.
• a conduit which nonetheless forms a part of the closed chamber which has an inlet at a lower position within the chamber such that this inlet will be below a normal liquid level within the chamber, and an upper outlet which will direct liquid into a holding reservoir of the type previously described for feeding conduits to eventually feed injector conduits.
• a member to provide a source of heat targeted to any material within the vertical conduit is provided in an adjacent vicinity to this vertical conduit.
• the way in which the heat can be provided can vary significantly from an electrical resistance coil to a conduit connected to a hot water supply. This is a useful adjunct if additional lift of liquid is required in the circumstances of a specific mold.
• the effect within the conduit therefore is to effect a boiling of the liquid within the conduit and the result that liquid in the manner of a percolator is then lifted by the rising vapour from the inlet through to the outlet.
• the result is achieved by having one or more dams or reservoirs which hold a limited amount of the liquid and which are arranged to collect the liquid from time to time during the "boiling" of the liquid in the chamber either by reason of rapid transition to vapour effects causing substantial ebullition and therefore implicit lifting of the liquid to appropriate heights, or by reason of condensate being directed to one or more of the dams or reservoirs.
• foaming agent can also in preference a combination of foaming agent and distributed reservoirs or dams.
• the reservoir or dam or dams can be arranged to overflow as they are filled with the liquid and this cascading effect can ensure that each of the reservoir and dams are kept to only a selected level and therefore head pressure and therefore maintain a reasonably small range of temperatures at which the liquid will boil within any selected reservoir or dam.
• a surface material is applied to an inner wall of the chamber above a base level of liquid in the chamber, which surface material will assist in retention of liquid in close vicinity to the wall providing thereby a further effective height for the liquid.
• At least some parts of the inner surface of the chamber are coated with a material so that surface tension implicit between the liquid and the material will assist in continuing retention of the liquid against the wall.
• flock in the form of a number of short strands of fibre are attached end on in close vicinity one to the other, to the surface so that liquid which reaches any such selected area thus treated, will be held to be of greater depth and therefore act as a greater reserve.
• This then allows for a greater tolerance in a refresh rate of liquid needed to keep the surface wet.
• the amount of liquid available will be greater than with a smooth surface and allow therefore more tolerance in any replacement of liquid that might be being used.
• the replenishment of liquid mechanism can be variously a flow from vapour being condensed above the selected area and therefore seeping or pouring over the area, it can be caused by splattering or spraying from devices within the chamber, it can be subject to replenishment by rising foam, or it can be subject to replenishment simply by ebullient action of the liquid during any boiling action.
• the invention then could be said to reside in a mold for molding of plastics material where there is a closed chamber using the heat transfer system described to effect a transfer of heat, characterised in that at least some of the surface of the chamber has attached thereto further material or materials to assist in retention of the liquid in the adjacent vicinity of a target surface of the wall of the chamber.
• the liquid is water.
• the materials added are a flock which is adhered by an appropriate adhesion process so that the respective particles of flock are secured end on to the surface of the chamber.
• the thus treated surface is replenished with water from time to time during an operation of the mold by liquid being supplied from above.
• replenishment is effected by foam causing film of the liquid to pass across the selected surface area wetting this thereby.
• this can be said to reside in the method of effecting heat transfer within a closed chamber for the purposes described where the method includes having within the closed chamber only liquid, and the vapour of liquid within a space above the liquid within the chamber, and where a surface of the chamber selected for purpose of extracting heat therefrom is above a level of the liquid within the chamber and effecting replenishment of liquid in respect of that selected area from time to time where the selected area includes a treatment to effect retention of the liquid by use of surface tension of the liquid.
• Temperatures of a mold depend to some extent upon the thickness of the metal between the heat source (e.g. a molding surface) and the selected area within the closed chamber. If there is a greater thickness, then there will be a temperature gradient that depends on the various characteristics of the metal of the mold and the respective temperatures at each side. This can be taken advantage of in allowing some parts of a molding surface to be at a different temperature than others.
• the heat source e.g. a molding surface
• Figure 1 is a perspective view with part cross section of one part of a plastics injection mold including an inner chamber according to a first embodiment
• Figure 2 is a cross section of a part used in a further form of the invention.
• Figure 3 is a cross sectional view along the lines 4-4 in Figure 4 of a second embodiment
• Figure 4 is a cross sectional view of a second embodiment
• Figure 5 is a cross section of a third embodiment
• Figure 6 is a cross section of a portion of a mold according to a fourth embodiment which shows a visual indicator of evacuation status of a chamber.
• FIG. 1 there is shown here one part or half of a plastics material injection mold 1 where this one half of the mold has a quite arbitrarily chosen shape with a pin 2 extending from a middle of the molding shape 3.
• a mold to be fully operational will have a further part (which is not shown) forming in this case a female receiving shape which further part will have its temperature controlled with an arrangement and method substantially the same as this first part.
• a chamber 4 which is arranged to be closed and to have water inserted therein and air removed.
• the extent of removal of air (which in this case is achieved by applying a vacuum pump (not shown) to closable outlet 4a through a wall of the mold) such that substantially all of the air is removed so that only the vapour of the liquid in the chamber substantially fills any remaining chamber area.
• the liquid which is water in a preferred embodiment is first treated so that substantially all dissolved gases have been removed by, for instance, vigorously boiling the water at standard atmospheric pressure prior to insertion into the chamber 1. If a vacuum pump is used to evacuate air however, such dissolved air can also be removed subsequent to the water being introduced into the chamber 4 by use of the vacuum pump.
• the procedure to reduce dissolved gases has the added advantage that the water will be substantially without oxygen when in the closed area of the chamber and therefore deterioration of any metal surface by reason of oxidation (e.g. rust) which will ordinarily occur in existing systems will now not occur in so far that there is not a source of oxygen.
• reason of oxidation e.g. rust
• a small quantity of household detergent is added to the water, the quantity being dependent on the actual detergent being used but generally is a quantity that will result in adequate foaming under the mold operating conditions.
• 1% by volume of household detergent one example being a domestic detergent sold under the Trade Mark of Morning Fresh by the company Cussons Pty Ltd ACN 004 164 827 in Australia
• Alternative foaming agents can be used.
• this has a shallow trough 5 which is positioned immediately below heat exchanger 6 which is arranged to be kept cool by cooling water passing through the heat exchanger 6 and therefore effecting condensation of vapour rising in the chamber 4.
• the condensate is directed into the trough 5 and as it overflows the water will run down the side of the mold part 1 into a main body of liquid (water with detergent).
• a further percolator arrangement 7 is also in place to feed water into the trough 5.
• This has a vertical tube 8 with an inlet 8a at a bottom of the chamber in order to draw liquid into the tube 8 and an outlet 9 by which to direct lifted water into the shallow trough 5.
• a source of heat 10 is arranged alongside the tube 8 and this is provided with an electric resistance element so the quantity of heat can be easily controlled and therefore the quantity of liquid that will be lifted with this arrangement.
• the value of having a higher level of liquid is that the height can be used to push liquid into places it otherwise might be impeded from going, for instance by reason of surface tension effects.
• the example is a narrow passage 11.
• a needle injector 12 inserting liquid which is running down through tube 14 into the passage 11 where small quantities of liquid are squirted into the narrow passage so as to splash and coat the inner surface of the passage with water.
• This water is then delivered by a higher level of pressure but on delivery the water is allowed to simply coat the surface. This then allows the effect to keep the temperature of even a small part within a mold to within an acceptable degree of uniformity.
• a chamber 15 which has a plurality of cascading reservoirs 16 and 17 which are fed by liquid returning from the condenser area 19.
• Each reservoir 16 and 17 is shaped so that only a selected depth of water will stay in a respective reservoir and hence keep a temperature uniformity.
• the reservoir in each case is defined by walls 20 which are arranged to allow for overflow of the liquid when filled and such that the overflowing liquid will flow into the next reservoir underneath the first reservoir.
• the drawing shows an arrangement where however the water may to some extent follow an inward inclination of the wall 20 by reason of surface tension and therefore be directed as a cascade into the next reservoir beneath the first.
• the head of liquid in any reservoir is determined by the height of water in an individual reservoir and as such this can now be determined by a mold designer appropriate to any application.
• these are used with the liquid having foaming agent so that some of the advantages of both answers can be achieved in a single mold.
• some of the surface of the chamber has attached thereto a flock which is adhered by an adhesive so that the respective particles of flock are secured end on to the surface of the chamber.
• Temperatures of a mold depend to some extent upon the thickness of the metal between the heat source (e.g. a molding surface) and the selected area within the closed chamber. If there is a greater thickness, then there will be a temperature gradient that depends on the various characteristics of the metal of the mold and the respective temperatures at each side. This can be taken advantage of in allowing some parts of a molding surface to be at a different temperature than others.
• the heat source e.g. a molding surface
• FIG. 5 there is shown an injector system 40 which has a passageway 41 with an open top 42 positioned in a chamber 43. There is a narrow mold part 44 which is arranged to be fed water through the passageway 41.
• the open top is at a height somewhat above the height of the part 44 so that any water in the passageway will be forced through the passageway to its lowermost outlet 45.
• the mold 46 is again a part of an plastics injection mold with a condenser 47 located in a space 48 above a base level of any liquid 49.
• FIG. 6 there is shown a mold 21 for injection molding of plastics materials where there is within this, a chamber 22 which is arranged to hold water 23 and the shape of the chamber 22 is such that it will be located adjacent heat generating locations within the mold 21.
• the feature of this embodiment is that there is a passageway 26 connected to a main body of the water which passageway 26 progresses from a main body of the chamber to an external viewing location where the passageway is a vertical riser and where a top of the passageway at 27 is closed.
• the passageway 26 in this case is formed as a part of the mold except there is embedded within the external surface of the mold a transparent window 28 so that the height of liquid within the passageway will be visible to an external viewer.
• the effect previously described will be observable which is that the level 30 of the liquid will be an indication of the status of evacuation within the main space of the main chamber 22. If this is changed then this will be observable to an operator who can then establish whether a leakage into the main chamber has occurred and then take appropriate action.
• the height of liquid within the closed passageway will be a reflection of the evacuation status of the chamber overall.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Moulds For Moulding Plastics Or The Like (AREA)
• Forging (AREA)
• Bidet-Like Cleaning Device And Other Flush Toilet Accessories (AREA)

Priority Applications (9)

Applications Claiming Priority (4)

Publications (1)

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Country Status (14)

Families Citing this family (9)

Citations (3)

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• 1999
  • 1999-09-24 AU AUPQ3077A patent/AUPQ307799A0/en not_active Abandoned
  • 1999-10-11 AU AUPQ3334A patent/AUPQ333499A0/en not_active Abandoned
• 2000
  • 2000-09-25 CA CA002385500A patent/CA2385500C/en not_active Expired - Fee Related
  • 2000-09-25 NZ NZ518070A patent/NZ518070A/xx not_active IP Right Cessation
  • 2000-09-25 ES ES00965653T patent/ES2346846T3/es not_active Expired - Lifetime
  • 2000-09-25 CN CNB008150192A patent/CN1203975C/zh not_active Expired - Fee Related
  • 2000-09-25 US US10/089,121 patent/US7143814B1/en not_active Expired - Lifetime
  • 2000-09-25 EP EP00965653A patent/EP1226010B1/en not_active Expired - Lifetime
  • 2000-09-25 DE DE60044608T patent/DE60044608D1/de not_active Expired - Lifetime
  • 2000-09-25 WO PCT/AU2000/001160 patent/WO2001023158A1/en active IP Right Grant
  • 2000-09-25 KR KR1020027003836A patent/KR100701875B1/ko not_active IP Right Cessation
  • 2000-09-25 JP JP2001526348A patent/JP4639018B2/ja not_active Expired - Fee Related
  • 2000-09-25 AU AU76335/00A patent/AU766352B2/en not_active Ceased
  • 2000-09-25 AT AT00965653T patent/ATE472402T1/de active
• 2002
  • 2002-03-22 ZA ZA200202308A patent/ZA200202308B/xx unknown
  • 2002-08-08 HK HK02105804.3A patent/HK1044909A1/xx not_active IP Right Cessation

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Non-Patent Citations (2)

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