Method for molding a two-material part using a rotatable mold insert member

• US 6,296,796 B1
• Filed: 02/02/1999
• Issued: 10/02/2001
• Est. Priority Date: 02/02/1999
• Status: Expired due to Fees

• Current Assignee: TRW Inc. (Northrop Grumman Corporation)
• Original Assignee: TRW Inc. (Northrop Grumman Corporation)
• Inventors: Gordon, Gary G.
• Primary Examiner(s): Silbaugh, Jan H.
• Assistant Examiner(s): Lee, Edmund H.
• Application Number:
  US09/243,038
• Time in Patent Office: 973 Days
• Field of Search: 264/255, 264/310, 264/328.7, 425/112, 425/120
• US Class Current: 264/255
• CPC Class Codes: B29C 37/0078 Measures or configurations for obtaining anchoring effects in the contact areas between layers surface shaping B29C59/00; B29C66/02 takes precedence
• CPC Class Codes: B29C 39/021 by casting in several steps
• CPC Class Codes: B29C 45/1635 using displaceable mould parts, e.g. retractable partition between adjacent mould cavities

Abstract

A mold insert member is provided to enable molding unitary composite parts from two materials so that the materials co-diffuse at their interface. The insert member is rotatable relative to a stationary molding die to define, in a first position, a first molding cavity for receiving a first molding material and, in a second position, a second molding cavity contiguous with the first molding cavity adapted to receive a first molding material. The insert member includes a substantially circular cylindrical main body portion defining a longitudinal axis. At least one arcuate mold lip is formed on an end of the main body portion and is adapted to cooperate with a molding die when the insert member is disposed in a first position relative to the molding die. At least one cavity area is formed on the end of the main body portion. The cavity area is adapted to define, together with the molding die, a second molding cavity when the insert member is rotated into a second position. The second molding cavity is adapted to receive a second molding material. The insert member is rotatable relative to a stationary molding die so that the first and second materials can be injected into the molding die without opening the die between injection shots.

Claims

1. A method of molding a part from at least two moldable materials, the method comprising the steps of:

providing a mold having main mold members and a mold insert member forming a first cavity defining a first volume of the part;

filling the first cavity of the mold with a first moldable material;

without moving the insert member to avoid an impinging interference between i) the main mold members and the mold insert member, and ii) the first moldable material and the mold insert member, and without opening said mold, rotating the insert member relative to the main mold members to form a second cavity defining a second volume of the part, wherein the second cavity is disposed adjacent the first moldable material;

filling the second cavity of the mold with a second moldable material such that it contacts the first moldable material; and

,

opening the mold to release the part.

2. The method according to claim 1 wherein the step of providing the mold insert member includes providing a mold insert member having cylindrical symmetry.

3. The method according to claim 1 wherein the step of filling the second cavity of the mold with the second moldable material includes filling the second cavity of the mold with the second moldable material before said first moldable material cools and shrinks a substantial amount so that the second moldable material bonds to the first moldable material.

4. The method according to claim 3 wherein:

the step of filling the first cavity of the mold with the first moldable material includes injecting the first moldable material into said first cavity; and

the step of filling the second cavity of the mold with the second moldable material includes injecting the second material into the second cavity.

5. The method according to claim 1 wherein the step of rotating said insert member includes rotating the insert member substantially one quarter turn.

6. The method according to claim 1 wherein the step of filling the second cavity of the mold with the second moldable material includes filling the second cavity of the mold with the second moldable material within a time period to enable the first and second materials to co-diffuse at their respective interface surfaces.

7. The method according to claim 1 wherein:

the step of providing said mold includes providing a mold having i) a first cavity defined in part by cooperative main mold portions and a first surface of said mold insert member selectively rotatable to a first position relative to the cooperative mold portions and ii) a second cavity defined in part by said cooperative mold portions and a second surface of said mold insert member selectively rotatable into a second position relative to the cooperative mold portions;

the step of filling the first cavity of the mold with the first moldable material includes positioning said mold insert member into said first position;

the step of filling the second mold cavity with said second moldable material includes positioning said mold insert member into said second position; and

,

the step of rotatably moving a portion of the mold to form said second cavity includes rotating said insert member 90°

.

8. The method according to claim 7 wherein:

the step of filling the first cavity of the mold with said first moldable material includes injecting a one of a polypropylene material and a nylon material into said first cavity; and

,

the step of filling the second cavity of the mold with said second moldable material includes injecting thermoplastic elastomer material into said second mold cavity.