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
  • B29C45/1701—Component parts, details or accessories; Auxiliary operations using a particular environment during moulding, e.g. moisture-free or dust-free
• • 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
  • B29C2791/00—Shaping characteristics in general
  • B29C2791/004—Shaping under special conditions
  • B29C2791/006—Using vacuum
• • 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
• • 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
  • B29C45/2725—Manifolds
• • 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
  • B29C45/34—Moulds having venting means
• • 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
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
• • 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
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
  • B29C48/50—Details of extruders
  • B29C48/68—Barrels or cylinders

Definitions

• the present invention concerns a method for moulding by injection or extrusion.
• the invention moreover regards the means for implementation of the aforesaid method.
• plastic material is heated; then, with different methodologies, once it has assumed the desired final shape, it is cooled and hence acquires the necessary and desired consistency and manageability.
• injection moulding of plastic materials the objects assume their shape because an injection press forcedly introduces into a mould material in the molten state, which fills a cavity. In this cavity, the material cools in a period of time that depends upon the characteristics of the shape of the piece that is to be produced, upon the technical, chemical, and physical characteristics of the material injected and pressed in the cavity, and upon the characteristics of conditioning outside to the cavity. The same occurs in the sector of extrusion of plastic materials and other materials, where in a continuous cycle the material assumes the shape of a particular profile obtained to meet specific requirements.
• thermosetting materials These materials present characteristics that differ from what has been illustrated with reference to the processing of plastic materials. In fact, these materials are injected and pressed in the cold state in a heated cavity. Following manufacturing processes indicated by the producer of each individual material, they become an object that can be used, for example, the important parts of light assemblies of means of transport. The same applies to the sector of die-casting and injection of the materials that we shall define by way of example as metal materials, such as aluminium and its alloys or, once again as example, magnesium. These materials are treated, i.e., processed, in a hot environment both in the injection or pressing stage and in the cooling stage.
• All the above production members, tools, means (tools) are rich in technical elements that synergistically contribute to the production of objects of various nature.
• These technical elements may be, for example, electrical resistors, induction coils necessary for creating electromagnetic fields, solenoid valves, extractors, thermostats, sensors of various sorts, screws with particular profiles, electrical connectors and conductors, insulating materials of various nature and with different purposes: all these constitute the environment in which the process of production occurs. All these production members, tools, means ( tools) ( moulds, plasticizing cylinders, etc. ) interact with the outside world, affecting it and being affected thereby and are conditioned by the various chemico-physical phenomena that are generated naturally around them.
• a mould for the production of objects made of polypropylene is damaged by the rust that' is formed on account of the condensation phenomena inside it, in cavities and gaps.
• rust modify the nature of the surfaces from an aesthetic standpoint, but it affects and modifies the structure of the mould itself, a fact that involves considerable maintenance costs.
• the same mould can be equipped with complementary accessories made of copper or other alloys; it may be provided with devices suitable to increase its productivity and requires heating elements.
• the thermal stresses modify the conditions of the electrical-connection points provided inside, oxidize all the parts that are subject to oxidation - typically the parts made of copper whatever the alloy thereof, the electrical conductors, etc.
• Mr is not a fixed and constant physical element; it varies its nature and composition as a result of multiple known factors. Atmospheric phenomena, its temperature, and its chemical composition affect its characteristics. Air hence affects with all its variables, which are not always parameterizable, the surrounding environment. Air and whatever is contained therein are hence a cause of:
• a first object of the invention is to provide a method for moulding by injection or extrusion that will enable all the adverse phenomena listed above to be reduced, contained, or eliminated.
• Another object of the invention is to provide means for implementation of the aforesaid method that will be simple as regards structure and safe and reliable in operation.
• the invention provides a method for moulding by injection or extrusion, basically characterized in that the air that surrounds or is contained inside the moulds for plastic materials or for rubber, or in dies for die-casting or injection of metals, such as aluminium and its alloys, magnesium, etc. , in moulds for thermosetting materials, in plasticizing sleeves of injection presses and in sleeves for extrusion of thermoplastic materials is eliminated before and/or during the manufacturing process, which in this way is carried out in a vacuum environment.
• the invention provides means for implementation of the aforesaid method, which basically comprise at least one vacuum chamber enclosing in a sealed way the working environment in which the method described above is implemented.
• suitable tools, members, and the like that enable seal of the system in which vacuum is to be obtained
• suitable tools, means, and the like to produce and maintain the vacuum in the system itself
• elements, means or members that constitute an interface or else a connection between the vacuum system and the outside environment, for example, for passage of the electrical conductors or for passage of structural elements necessary for operation of the machines .themselves, or for passage of conditioning pipes.
• FIG. 1 is a schematic illustration in partial vertical section of a known press for injection of plastic material
• - Figure 2 is a view similar to that of Figure 1, but in which a sleeve or casing for containment of the plasticizing cylinders in a vacuum chamber according to the invention is illustrated both in the disassembled state and in the state where it is assembled in its operating position on the press
• - Figure 3 is a schematic cross-sectional view of a known mould for plastic materials, viewed from the so-called injection side;
• FIG. 4 is similar to Figure 3, but at a reduced scale and with an illustration also of hermetic-seal means according to the invention arranged between components of the mould itself;
• - Figure 6 is a view in cross section and at a larger scale of the detail VI of Figure 5; and - Figure 7 is a view in the direction of the arrow VII of the mould of Figure 4, but completed with further hermetic-seal means according to the present invention.
• Figure 1 is a schematic representation of a known injection press, which is very similar to an extruder for plastic materials.
• the reference A designates the plasticizing cylinder.
• the reference B designates one of the heating elements used to bring the cylinder A to the working temperature.
• Figure 2 illustrates a press similar to that of Figure 1, in which the reference C designates an example of sleeve or casing for containment of the plasticizing cylinders so as to provide a vacuum chamber according to the invention.
• Said casing is represented both assembled in its operating position on the press and dismantled from the press itself.
• the elements in themselves known) useful for assembly of said casing on the press in conditions of hermetic seal, i. e. , flanges, thermal-expansion compensators, seals, etc. , are not illustrated.
• the reference D designates a device for hermetic connection of the casing C to the outside environment, for sealed connection, for instance, of the various circuits of the press, of the measuring and detection means, and so on.
• Figure 3 of the drawings is a schematic illustration of a known mould for plastic materials, viewed from the side defined as "injection side" and inside which a system is set for direct injection of plastic, made up of a distribution plate designated by Al and two injectors designated by Bl. There exist different ways for heating the aforesaid injectors and the distribution plate, of which Figure 3 is only an example.
• the reference F designates a gap in which vacuum is made, i. e. , from which - according to the invention - the air is removed to improve thermal insulation between the hot parts, inside the gap, and the cold parts, outside the gap.
• Designated by 0 are means for hermetic seal between contiguous members or plates, constituted, for example, by 0- rings suitable for vacuum sealing according to this example of embodiment of the invention.
• Figure 6 shows moreover in detail the seat of an injector covered by a resistive heating element.
• the injector ( bushing) is designated by I.
• the hot runner ( manifold) is designated by M, whilst the vacuum gap, from which the air is evacuated, is designated by F.
• Figure 7 illustrates the mould according to Figure 4 hermetically sealed also at the base and at the top by means of two seal plates G, one bottom plate and one top plate, respectively, to enable evacuation of the air from the internal cavity of said mould in a simple and inexpensive way.
• the vacuum is thus obtained and/or maintained before and/or during the manufacturing process, by using suitable means, such as, for example, a vacuum pump P, external to the mould and connected in a sealed way thereto by means of a pipe T branching as far as the internal gap F of the mould itself.
• said vacuum chamber is obtained by means of a permanent-vacuum container. It may be noted that the vacuum can be created not only using mechanical suction means ( vacuum pumps) , but also by means of chemical reaction in the aforesaid vacuum chamber, for example, with the use of substances designed for removal of gas ( getter substances) .

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• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Mechanical Engineering (AREA)
• Injection Moulding Of Plastics Or The Like (AREA)
• Extrusion Moulding Of Plastics Or The Like (AREA)
• Casting Or Compression Moulding Of Plastics Or The Like (AREA)
• Moulds For Moulding Plastics Or The Like (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=39970831

Family Applications (1)

Country Status (2)

Citations (11)

Family Cites Families (1)

• 2007
  • 2007-06-21 IT IT000447A patent/ITTO20070447A1/it unknown
• 2008
  • 2008-06-20 WO PCT/IB2008/001629 patent/WO2008155647A2/en active Application Filing

Patent Citations (11)

Non-Patent Citations (1)

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