Mold and method for injection-molding a part with a projecting portion

• US 20120326354A1
• Filed: 05/16/2012
• Published: 12/27/2012
• Est. Priority Date: 05/17/2011
• Status: Active Grant

• Current Assignee: Valeo Vision (Valeo SE)
• Original Assignee: Valeo Vision (Valeo SE)
• Inventors: DESMAZIERES, Michel, GOSSELIN, François
• Granted Patent: US 9,221,205 B2
• Time in Patent Office: Days
• US Class Current: 264/313
• CPC Class Codes: B22D 17/22 Dies manufacture, see the appropriate class, e.g. B23P15/24; Die plates; Die supports; Cooling equipment for dies; Accessories for loosening and ejecting castings from dies
• CPC Class Codes: B29C 2045/563 Enlarging the mould cavity during injection
• CPC Class Codes: B29C 45/0025 Preventing defects on the moulded article, e.g. weld lines, shrinkage marks preventing defects on the preformed parts or layers B29C45/14836
• CPC Class Codes: B29C 45/56 using mould parts movable during or after injection, e.g. injection-compression moulding B29C45/1705 and B29C45/572 take precedence
• CPC Class Codes: B29C 45/561 Injection-compression moulding
• CPC Class Codes: B29L 2031/747 Lightning equipment

Abstract

A mold and a method for the molding by injection of plastic material of a generally thin part, notably of a vehicle lighting and/or signalling device. The mold comprises two half-molds designed to be disposed one against the other and forming an enclosure designed to be filled with plastic material by injection. The plastic material is injected via an injection nozzle in the vicinity of one end of the part. The volume formed by the mold includes a cavity the volume of which may be modulated by means of a mobile element. During the injection of plastic material, when the latter has reached at least the level of the cavity, the initially zero volume of the cavity is progressively increased via the control means of the mobile element.

Claims

1. A mold element for molding parts by injection of a plastic material, comprising:

a surface designed to receive said plastic material and to form said part, said surface including a cavity adapted to form a projecting portion of said part;

said mold element includes a mobile element in translation in said cavity, said mobile element being adapted to modulate to volume of said cavity during said molding of said part.

2. The mold element according to claim 1, wherein said mobile element is configured so that it may be disposed with its terminal exterior surface at level of an opening of said cavity, notably flush with said opening.

3. The mold element according to claim 1, wherein said cavity is of generally elongate shape in a longitudinal direction, said mobile element being mobile in the longitudinal direction and preferably occupying a greater part, preferably at least 80%, more preferably at least 90% of a section of said cavity.

4. A mold for molding a part by injection of said plastic material, comprising at least two mold elements designed to cooperate with each other to form an enclosure corresponding to a shape of said part to be formed and designed to receive said plastic material in a main flow direction, wherein at least one of said mold elements conforms to claim 1.

5. The mold according to claim 4, wherein said cavity is disposed generally transversely to a main direction of flow of said plastic material during fabrication of said part by injection.

6. The mold according to claim 4, wherein said part has a generally thin shape, preferably having a substantially layer shape, said projecting portion formed by said cavity projecting from the thin part, notably from a main face of said part.

7. The mold according to claim 4, wherein it includes a passage for feeding said plastic material into a molding cavity, said molding cavity being disposed downstream of said passage in the direction of flow of said plastic material during molding.

8. A method for molding a part by plastic injection, comprising the following steps:

a) making available a mold forming an enclosure corresponding to the shape of said part to be formed, said enclosure including a cavity designed to form a projecting portion of said part;

b) injection of a plastic material into said enclosure of said mold;

c) modulation of a volume of said cavity in the direction of an increase in said volume during the step b).

9. The molding method according to claim 8, wherein said modulation in said step c) consists in increasing said volume of said cavity when a level of said plastic material has reached an inlet of said cavity.

10. The molding method according to claim 9, wherein said modulation in said step c) takes place when said plastic material present in and/or in front of said inlet of said cavity has not yet solidified.

11. The molding method according to claim 8, wherein said modulation in said step c) starts from a volume of said cavity less than 20%, preferably 10%, more preferably 5% of a final volume of said cavity.

12. The molding method according to claim 8, wherein said mold comprises at least two mold elements designed to cooperate with each other to form an enclosure corresponding to a shape of said part to be formed and designed to receive said plastic material in a main flow direction.

13. The molding method according to claim 8, wherein said molded part is a vehicle lighting and/or signalling device element and said projecting portion formed by said cavity is for example a stud.

14. The molding method according to claim 8, wherein said projecting portion of said part has a volume less than or equal to 15%, preferably 10%, more preferably 5% of a total volume of said part.

15. A vehicle lighting and/or signalling device element comprising a projecting portion that it is produced by the method according to claim 8, said production method being noteworthy in that an end of said projecting portion has an edge formed by the step c).

16. A molding method according to claim 8, wherein said method uses a mold element for molding parts by injection of a plastic material, comprising:

a surface designed to receive said plastic material and to form said part, said surface including a cavity adapted to form a projecting portion of said part;

said mold element includes a mobile element in translation in said cavity, said mobile element being adapted to modulate to volume of said cavity during said molding of said part.