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
  • B29C45/14—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor incorporating preformed parts or layers, e.g. injection moulding around inserts or for coating articles
  • B29C45/14065—Positioning or centering articles in 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
  • B29C33/44—Moulds or cores; Details thereof or accessories therefor with means for, or specially constructed to facilitate, the removal of articles, e.g. of undercut articles
  • B29C33/52—Moulds or cores; Details thereof or accessories therefor with means for, or specially constructed to facilitate, the removal of articles, e.g. of undercut articles soluble or fusible
• • 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
  • B29C45/14—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor incorporating preformed parts or layers, e.g. injection moulding around inserts or for coating articles
  • B29C45/14836—Preventing damage of inserts during injection, e.g. collapse of hollow inserts, breakage
• • 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
  • B29C33/44—Moulds or cores; Details thereof or accessories therefor with means for, or specially constructed to facilitate, the removal of articles, e.g. of undercut articles
  • B29C33/52—Moulds or cores; Details thereof or accessories therefor with means for, or specially constructed to facilitate, the removal of articles, e.g. of undercut articles soluble or fusible
  • B29C2033/525—Cores made of frozen liquids, e.g. ice

Definitions

• This invention relates to a method of manufacturing a hollow plastics article.
• Another method which is previously known is the so-called rotary moulding process, in which the plastics material in plastic state is entered into a cavity which rotates. The plastics material spreads over the walls of the cavity and covers the walls. When the plastics material has stiffened a shell having the intended shape has been obtained.
• a drawback of this method is that it is limitated with respect to accuracy , wall thickness, material to be chosen and shrinking problems.
• a third well-known method is the so-called blow moulding, in which an extruded plastics tube in heated condition is entered into a cavity in which the tube is blown or sucked to the walls of the mould in order to form the cavity.
• this method can only be used with thermoplastics and for articles of simple shape. It is also known to use cores of plaster or sand with suitable bonding agents in order to form articles with cavities but remainders of the plaster or sand core can stay in the article after cleaning, which for instance in petrol tanks for combustion engines can cause engine failure.
• German OS 18 10 311 Still another method of manufacturing articles of the above type is described in German OS 18 10 311. According to this method a core for instance of ice is produced which shapes the cavity during the injection. The core is then allowed to melt and the water is removed by an opening in the article.
• OS 28 83 566 is to produce a core consisting of bellows containing particles which are stabilized to solid shape by means of vacuum. After injection moulding around the core air of atmospheric pressure is allowed to enter into the bellows which then together with the particles can be taken out from the article.
• the object of this invention is to provide another method of manufacturing articles of the shape concerned which compared to known methods has the advantage that different materials can be integrated to a single unit. For instance
• O PI it is possible to combine an impact-resistant material and a chemically resistant material. Such a combination can be used for instance in chain saws when a petrol tank shall be an integrated part of the saw.
• Fig. 1 is a vertical length section through an article according to the invention and Fig. 2 is a vertical section on the line H - II of Fig. 1 with the article in the tool.
• Fig. 1 shows a detail of a chain saw, the detail being injection moulded in plastics and comprising an outer hull 10 of impact-resistant plastics into which the sword of the saw is to be fastened.
• the hull 10 continues into a handle 11 and encloses a container 12.
• the object of this container is to hold fuel for the chain saw.
• the detail is manufactured in the following way.
• a container 12 with an opening 13 is made.
• the container is filled with water and a mandrel 14 is inserted through the opening 13 so that a part of the mandrel extends outside the container.
• the container is cooled so that the water freezes to ice 15. This causes the container to expand a little at the same time as the mandrel is fixed to the container.
• the container with mandrel is inserted into the tool, the two halves of which being denoted 16 and 17, respectively.
• the mandrel is inserted in a corresponding hole 18 in the tool.
• the melted plastics, forming the hull 10 and the handle 11, is entered through several gates 19 so that the plastics will completely surround the container 12.
• the injection moulded article is then taken out from the tool and is placed with the opening 13 directed downwards.
• the ice melts, the mandrel falls out and the water escapes through the opening 13.
• the article can be completed with engine, sword and other details.
• the container can for instance be particles. By creating a vacuum in the container the particles can form a hard interior counter -acting the said pressure.

Landscapes

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

Priority Applications (1)

Applications Claiming Priority (1)

Publications (1)

Family

ID=20349909

Family Applications (1)

Country Status (5)

Cited By (13)

Families Citing this family (2)

Citations (4)

• 1983
  • 1983-02-07 SE SE8300614A patent/SE8300614D0/sv unknown
• 1984
  • 1984-02-07 DE DE19843490046 patent/DE3490046T1/de not_active Withdrawn
  • 1984-02-07 JP JP50069084A patent/JPS60500410A/ja active Pending
  • 1984-02-07 WO PCT/SE1984/000036 patent/WO1984003065A1/en active Application Filing
  • 1984-02-07 GB GB08423718A patent/GB2144074B/en not_active Expired
  • 1984-09-21 SE SE8404742A patent/SE450823B/sv not_active IP Right Cessation

Patent Citations (4)

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