Browse Prior Art Database

Injection Molding with Reduced or Negative Draft

IP.com Disclosure Number: IPCOM000044891D
Original Publication Date: 1983-Jan-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 60K

Publishing Venue

IBM

Related People

Hickey, TE: AUTHOR

Abstract

Molded rectangular articles, such as the covers for office equipment, are typically formed with sides that are slightly angled rather than being perpendicular so that mold sections can be withdrawn without marring surface appearance. This article describes a technique for molding covers that allows perpendicular or even reverse angled sides to be molded.

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Injection Molding with Reduced or Negative Draft

Molded rectangular articles, such as the covers for office equipment, are typically formed with sides that are slightly angled rather than being perpendicular so that mold sections can be withdrawn without marring surface appearance. This article describes a technique for molding covers that allows perpendicular or even reverse angled sides to be molded.

Referring to Fig. 1, a mold arrangement is shown, in cross-section, for producing a cover 8. A depressed parting line 10 is formed along the center of the connecting cover section 12 using a mold section 11. Each of two corresponding mold sections 14 and 16 forms a portion of the center section 12 and a respective intersecting cover section 18 or 20. A core mold section 22 serves to define the inside surfaces of the cover

To avoid marring the outside surfaces of the cover section 12, the mold section 11 is withdrawn in a direction perpendicular to the plane of cover section 12 (see arrows). The mold section, however, is withdrawn at an angle intermediate the perpendicular to the cover sections 12 and 18. In a like manner, the mold section 16 is withdrawn at an angle intermediate the perpendicular to cover sections 12 and 20. Such angled withdrawal of mold sections is achievable with angle camming techniques that are known in the art. With this geometry, sufficient angle of withdrawal is achievable from all outside surfaces to avoid marring, even for textured surfac...