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
  • B29C45/26—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
  • B29C2045/2743—Electrical heating element constructions
  • B29C2045/2748—Insulating layers covering the electrical heating element
• • 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
  • B29C33/06—Moulds or cores; Details thereof or accessories therefor with incorporated heating or cooling means using radiation, e.g. electro-magnetic waves, induction heating

Definitions

• Heating device in particular for use in injection molds for processing thermoplastic
• the present invention relates to a heating device, in particular for use in injection molds for processing thermoplastic materials, with an essentially hollow profile-shaped housing and a heating unit, in particular Schuwen ⁇ del, which can be subjected to heating current in / on the housing.
• Such heating devices are used as so-called tubular heating cartridges or heating tapes, for example in order to bring sprue channels of sprue devices (hot runner nozzles and distributors) to a predeterminable temperature or to keep them at a predeterminable temperature, so that a constant flow of this in the flow area to ensure thermoplastic materials.
• heating devices of this type are used in the area of heat pipes, which are used to temper mold zones or hot runner nozzles and hot runner distributor bars.
• Heating devices are known in which the heating coil is cast with copper or brass. On the outside, these encapsulated heating cartridges are surrounded by a jacket made of non-rusting steel. These heating cartridges have the disadvantage of a relatively large heat radiation to the outside. This heats components that do not actually require heating what has a negative impact on the overall energy balance.
• the present invention is based on the object or the technical problem of specifying an improved heating device of the type mentioned at the outset, which ensures optimum heating properties, a simple structure at the points at which the thermal energy or heating energy is required has and thus ensures a rational production and can also be used reliably in continuous operation.
• a further task consists in specifying a reliably working sprue device or nozzle device which is small in size and emits as little heat as possible to its surroundings.
• the heating device according to the invention is given by the features of claim 1.
• Advantageous refinements and developments are the subject of the dependent claims.
• the heating device according to the invention is characterized in that a layer-like insulating device surrounding the heating unit on the inside or outside is present at least in some areas.
• the heating element according to the invention ensures that the heat is supplied to an increased extent where it is needed. If the insulation device is arranged on the outside, the heating device is preferably suitable for use for sheathing a nozzle needle of a pouring device, since in this case the heat is primarily fed inwards to the nozzle duct in order to keep the thermoplastic mass flowing therein at a predeterminable temperature.
• heating devices according to the invention can be pushed onto heat pipes in the same advantageous manner.
• the heating device according to the invention is preferably used as a heating tape for external heating. Conversely, if the insulation layer is arranged on the outside, the heating device can be used as a heating band for internal heating.
• a particularly preferred embodiment of the heating device according to the invention is characterized in that the insulating device is constructed in sandwich construction with at least one insulating layer.
• the heating device according to the invention preferably has the following layered structure: wear-resistant layer with a relatively low coefficient of thermal conductivity and insulating layer, in the order from the inside out or in reverse order, depending on which side the heating device is exposed to increased wear.
• heating device with the following layer-by-layer structure is also possible according to the invention: wear-resistant layer, insulating layer and wear-resistant layer.
• Titanium or a titanium alloy is preferably used as the material for the wear-resistant layer, which has a relatively low coefficient of thermal conductivity compared to the steel usually used as the housing wall. In addition, this material ensures excellent wear and tear Strength properties. Ceramic, mica, air, vacuum or the like are preferably used as the "material" for the insulating layer.
• the insulation unit can also be placed as formwork for casting the heating coil with heat-conducting material, which allows particularly cost-effective production.
• the heating coil With regard to good heat transfer from the heating coil to the component to be heated, it is advantageous to cast the heating coil with a very good heat-conducting material (e.g. copper, copper alloy, brass, etc.) at least in some areas.
• a very good heat-conducting material e.g. copper, copper alloy, brass, etc.
• a preferred embodiment is characterized in that the heating unit (heating coil) is encapsulated in some areas such that the heating coil itself still protrudes in some areas from the encapsulation area and that in the case of an insulating device lying on the protrusion, an insulating air layer is additionally provided between the casting compound and the insulating device ⁇ is available.
• An injection mold according to the invention with a hot runner for processing thermoplastic materials is characterized in that at least one heating device according to the invention is arranged.
• a pouring device (hot runner) according to the invention for an injection mold for processing thermoplastic material is characterized in that the pouring device has at least one heating device according to the invention in an integrated design.
• the heating device With the heating device according to the invention, energy savings can be realized which are up to 50% and more compared to the previously known heating devices. Furthermore, it is possible to achieve compact dimensions, since the dimensions for the heating unit itself can be kept smaller as a result of the improved supply of heat to the places where the heat is required. The temperature of the tool itself is reduced.
• 1 schematic sectional view of a heating device with an insulating device for a heat pipe
• 2 schematic sectional view of a heating device with an insulating device for a nozzle device
• Fig. 10 Detail from the wall of a heating cartridge with a layered insulation device according to a fourth
• Fig. 12 schematic section through a nozzle device with heating device. WAYS OF CARRYING OUT THE INVENTION
• a heating device 10 which rests on the outer circumference of the heat pipe 26, is arranged on the outside of a heat pipe 26, which is used in particular for temperature control of mold zones (not shown).
• the heating device 10 itself initially has a first casting layer 24 made of brass from the inside to the outside, within which a heating unit or heating coil 12 is cast.
• the potting unit 24 surrounds an insulating device 20. Since an increased heating power is required in the edge area, the pitch of the heating coil 12 is reduced in this area.
• the heating device 11 shown schematically in FIG. 2 is applied on the outer peripheral side to the nozzle channel 34 of a nozzle device 32. It has a structure similar to that of the heating device 10 according to FIG. 1, but in addition to a first insulating layer 30.1 there is a second insulating layer 30.2 on the outside.
• the first insulating layer 30.1 can be made of ceramic or mica.
• the second insulating layer 30.2 is simultaneously designed as a wear layer and consists of a titanium alloy with a low thermal conductivity.
• a heating tape 13 is shown schematically, which is used for external heating.
• the heating unit 12 with its potting layer 24 is arranged on the outside.
• the heating tape 15 shown in FIG. 4 is suitable for so-called internal heating, ie an insulation device 50 is located on the outside thereof and in this exemplary embodiment has a first insulation layer 50.1 and a second insulation layer 50.2.
• the power supply of the heating unit 12 is not shown in FIGS. 1 to 4.
• FIG. 7 of the wall of a heating device 25, which is designed as a cylindrical heating cartridge 25, consists of the following layered structure.
• a potting unit designed as a potting layer 24, within which the heating coil 12 is potted.
• the individual Schuwen ⁇ delqueritese 12 are not completely encapsulated by casting compound, so that they protrude outwards.
• the partially encapsulated heating coil 12 is surrounded on the outside by an insulating device 70, which has the following structure.
• the protruding heating coil elements 12 are first connected to a first wear layer 18, which consists of a titanium alloy with a low coefficient of thermal conductivity.
• a first wear layer 18 which consists of a titanium alloy with a low coefficient of thermal conductivity.
• the heating coil cross sections are flattened in the area of the encapsulation layer 24 surrounding them.
• the heating cartridge 21, shown schematically in FIG. 5, is designed similarly to the detailed illustration of the heating cartridge 25 according to FIG. 7 with an air layer 14 between the heating device 12 and an outside insulation device 60, however, the insulating device 60 consists only of an outer wear layer 16 and an inner insulating layer 22, the heating coil 12 having a square profile.
• the heating cartridge 21 is closed off at the end by circular ring profiles 44, the thickness of which corresponds to the thickness of the casting layer 24, the air layer 14 and the inner insulating layer 22.
• a current connection unit 36 to the heating unit 12 is also shown schematically in FIG.
• the heating cartridge 23 shown in FIG. 8 differs from the heating cartridge according to FIG. 5 in that the provision of an additional insulating air layer 14 has been dispensed with here and the encapsulation layer 24 extends right up to the insulating layer 22, i.e. the heating coil 12 is almost completely potted with brass.
• the schematic partial section of the wall of a heating cartridge 27 shown in FIG. 10 has the same layer-by-layer insulation device 70 as the heating cartridge 25 according to FIG. 7.
• the heating device 12 has a heating coil with a circular profile, the individual coils being completely surrounded by a casting unit 24 and the insulating device 70 directly connecting to the outside of the casting layer 24.
• the potting compound can consist of brass, copper or other heat-conducting alloys.
• the insulating wear layers preferably consist of titanium or titanium alloys, the underside of which is polished. Ceramic or mica is preferably used as the material for the insulation layer.
• the insulation layer can also be designed as an air layer or vacuum layer.
• the heating cartridges 21, 23, 25, 27 have a constant inner diameter, so that they can easily be pushed onto a nozzle device of an injection mold for processing thermoplastic materials.
• FIG. 11 shows schematically the simple manner in which the heating device 90 according to the invention with the insulating device can be used to encase a casting device 110 in the region of a nozzle channel 102.
• FIG. 12 schematically shows in cross section a nozzle device 190 in which the heating device 99 is integrated between a nozzle head 100 made of special steel and a nozzle insert 101 made of special steel.
• the nozzle device 190 is designed as a disposable nozzle.
• the heating device 99 has the following layer-by-layer structure from the inside to the outside: cast brass layer 92 with heating coils 94 encapsulated therein, titanium alloy layer 95, mica filling 93 and finally a titanium alloy layer 91 on the outer circumference.
• the killing process is preferably used, in which brass is preferably used as the casting material for covering the heating coils.
• the nozzle device 101 according to FIG. 12 is preferably designed as a “micro nozzle” which has length dimensions of approximately 6 cm and diameter dimensions of approximately 1 cm.
• the heating device is designed as a cylindrical hollow element, the individual layers forming sleeves lying against one another at least in regions.

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

Priority Applications (5)

Applications Claiming Priority (4)

Related Child Applications (1)

Publications (1)

Family

ID=25961804

Family Applications (1)

Country Status (4)

Cited By (4)

Citations (7)

• 1995
  • 1995-02-23 AU AU17537/95A patent/AU690222B2/en not_active Ceased
  • 1995-02-23 WO PCT/DE1995/000226 patent/WO1995023680A1/de active Application Filing
  • 1995-02-23 CA CA002182482A patent/CA2182482C/en not_active Expired - Fee Related
  • 1995-02-23 JP JP7522618A patent/JPH09509625A/ja active Pending

Patent Citations (7)

Non-Patent Citations (2)

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