| 摘要 |
A shim for a compression mold for manufacturing a component from reinforced plastic, typically from SMC, comprising a fixed molding element, a mobile molding element, and a mobile shim that can be moved by an actuator. The mobile shim comprises a conventional part made of steel but also a part made of a high expansion material with a mean coefficient of expansion that is high enough that its own expansion at the molding temperature places the shim in compression against the molding element and seals against this element, thus eliminating flash on the molded part. This material is advantageously a polyetheretherketone, or PEEK. A mold comprising this shim and a compression molding method are also disclosed. |
| 主权项 |
1. A mobile shim for compression mold for manufacturing a reinforced plastic part by molding under a predetermined maximum molding pressure, said mold comprising a molding element, said mobile shim being displaceable in translation parallel to a mold closing direction, said mobile shim having a molding surface intended to come into continuous contact, during molding, with a molding surface on said molding element,
wherein said mobile shim comprises over at least part of its thickness, in a direction perpendicular to said mold closing direction, at least one high expansion component of determined configuration, said high expansion component comprising at least one or more high expansion materials, said at least one high expansion material having a mean coefficient of expansion sufficient so that the clearance between said shim and said molding element is zero at least when, during molding, said at least one high expansion component is heated to at least a molding temperature TM between 115° C. and 170° C., said at least one high expansion component having in addition a mean Young's modulus at the molding temperature ECHD, less than 20 000 MPa, a configuration of said at least one high expansion component and the one or more high expansion materials forming said at least one high expansion component are selected so that when said shim is assembled in said mold and during molding, said at least one high expansion component is heated from an ambient temperature of at least 23° C. to said moulding temperature, the expansion of said at least one high expansion component generates at a sealing region between said shim and said molding element a compression stress in a direction perpendicular to said mold closing direction, or increases said compression stress if it exists at ambient temperature, said compression stress being sufficient, when said at least one high expansion component is at said molding temperature, to guarantee sealing during molding between said mobile shim and said molding element, the temperature TM being considered at a mean level of this sealing region. |
