Ultra thin wall injection molding by utilizing film section insert and flow channels combination

• US 5,132,071 A
• Filed: 06/12/1991
• Issued: 07/21/1992
• Est. Priority Date: 02/20/1990
• Status: Expired due to Term

• Current Assignee: Sorensen Research & Development Trust
• Original Assignee: Jens Erik Sorensen
• Inventors: Sorensen, Jens O.
• Primary Examiner(s): Lorin, Hubert C.
• Assistant Examiner(s): ORTIZ, ANGELA Y
• Application Number:
  US07/713,795
• Time in Patent Office: 405 Days
• Field of Search: 264/132, 264/259, 264/263, 264/266, 264/268, 264/316, 264/328.12
• US Class Current: 264/259
• CPC Class Codes: B29C 45/0046 Details relating to the filling pattern or flow paths or flow characteristics of moulding material in the mould cavity
• CPC Class Codes: B29C 45/14778 the article consisting of a material with particular properties, e.g. porous, brittle

Abstract

Injected fluid plastic material directed to a predetermined side of a film section that is inserted into a mold cavity by utilizing a mold that includes a first mold part with a first mold-cavity section and a second mold part with a second mold-cavity section, a gate with a gate region, and a multitude of specific flow channels in the first mold-cavity section for directing injected plastic material away from the gate region; placing the film section in the second mold-cavity section so that the film section covers an extensive region of both the specific flow channels and the thin mold-cavity region and so that the film section does not cover a first segment of each of the specific flow channels which are closest to the gate region, but does cover a second segment of each of the specific flow channels which is a continuation the first segment of each of the specific flow channels; and injecting the fluid plastic material into the mold-cavity, so that the fluid plastic material flows away form the gate region and along the first segment of each of the specific flow channels until the fluid plastic material meets the film section whereby, because the specific flow channels are located in the first mold section, the fluid plastic material in each of the specific flow channels forces the film section toward the second mold section and the fluid plastic continues to flow along the second segment of each of the specific flow channels and between the first mold-cavity section and the film section, and the fluid plastic continues to flow into the thin mold-cavity region in a generally lateral direction from each of the specific flow channels, so that the fluid plastic material flows between the first mold-cavity section and the inserted film section.

Claims

1. A method of cyclically injection molding a plastic product with a film section component in a cavity of a mold that comprises a first mold part with a first mold-cavity section and a second mold part with a second mold-cavity section, the mold parts encompassing the mold-cavity therebetween, the method comprising the steps of:

(a) separating the first mold part from the second mold part to open the mold-cavity,

(b) providing a film section and inserting the film section into the opened mold-cavity,

(c) combining the first mold part with the second mold part, to close the mold-cavity and thereby enclose the film section in the closed mold-cavity,

(d) injecting fluid plastic material into the mold-cavity, so that the plastic material covers and bonds to the film section,

(e) solidifying the injected plastic material to form a product comprising a laminated section which includes said film section and at least a part of said plastic material,

(f) ejecting the solidified product;

the mold-cavity comprising a gate with a gate region, and a multitude of specific flow channels in said first mold-cavity section for directing injected plastic material away from the gate region, with the mold-cavity thickness at the specific flow channels being much thicker than the mold-cavity thickness of a thin mold-cavity region which is located between the specific flow channels, and the length of the specific flow channels being much greater than the width of the specific flow channels,

steps (b) and (c) comprising the step of;

(g) placing the film section in a portion of the mold-cavity so that the film section covers an extensive region of both said specific flow channels and the thin mold-cavity region, and so that the film section does not cover a first segment of each of said specific flow channels which are closest to the gate region, but does cover a second segment of each of said specific flow channels which is a continuation said first segment of each of said specific flow channels,

wherein within the portion of the mold-cavity containing the film section there are flow channels in only said first mold cavity section;

step (d) comprising the step of;

(h) injecting fluid plastic material into the mold-cavity, so that the fluid plastic material flows away from the gate region and along said first segment of each of said specific flow channels until the fluid plastic material meets the film section whereby, because the specific flow channels are located in only the first mold section, the fluid plastic material in each of said specific flow channels forces the film section toward the second mold section and the fluid plastic continues to flow along said second segment of each of said specific flow channels and between the first mold-cavity section and the film section, and the fluid plastic continues to flow into the thin mold-cavity region in a generally lateral direction from each of said specific flow channels, so that within the portion of the mold-cavity containing the film section, the fluid plastic material flows only between the first mold-cavity section and the inserted film section.

2. A method according to claim 1, wherein the film section comprises a film section of plastic.

3. A method according to claim 1, wherein step (b) comprises the step of:

(k) printing the film section prior to said insertion.

4. A method according to claim 1, wherein the width of a said flow channel is larger than the depth of the flow channel.

5. A method according to claim 1, wherein the general thickness of a part of the thin mold cavity region, minus the general thickness of a film section which cover such a part of the thin mold-cavity region, is less than 0.2 mm.