Method of injection-moulding onto a preformed web
AssigneeImperial Chemical Industries PLC
InventorBerwyn C. Thomas
Life of this patent
Estimating the term…
Abstract
In a method of injection-moulding articles of plastics material onto a preformed web inserted into the mould, the web is held under substantially constant tension during the closing of the mould, between a pair of clamps, the proximal clamp being fixed relative to the mould and the distal clamp free but bearing a load to furnish the desired tension in the web. The load may be imposed by a weight attached to the distal clamp, conveniently by means of an electromagnet.
Claims18
A method for injection moulding plastics material onto a preformed web comprising
- (a) advancing a free end of a length of web between separated male core and female cavity members of a mould until
- a distal portion of the free end protrudes from the mould, and
- a proximal portion of the free end, which has not advanced between the male core and female cavity members of the mould, is adjacent to the mould;
- (b) releasably engaging tensioning means to the distal portion, wherein said tensioning means controls the tension in the free end and is free to move as the distal portion moves;
- (c) holding against the tension only the proximal portion of the free end, leaving other portions of the free end capable of moving under tension in response to a movement of the male core relative to the female cavity which advances the male core into the female cavity in closing of the mould;
- (d) advancing the male core into the female cavity to close the mould so causing the distal end to move under tension and with it the tensioning means while the proximal portion is held against the tension;
- and
- (e) injecting plastics material onto the portion of the free end of the web which is between the male core and female cavity members of the mould.
A method of injection moulding plastics material onto cloth inserted between members of a core and cavity mould which comprises
- (a) advancing a free end of an indefinite length of cloth between separated male core and female cavity members of a mould until
- a distal portion of the free end protrudes from the mould, and
- a proximal portion of the free end, which has not advanced between the male core and female cavity members of the mould, is adjacent to the mould;
- (b) releasably engaging a tensioning device to the distal portion of the free end,
- wherein by means of said tensioning device a load can be applied to the free end to control its tension, the tensioning device being free to move as the distal portion moves;
- (c) holding against the load only the proximal portion of the free end, leaving other portions capable of moving under tension in response to a movement of the male core relative to the female cavity which advances the male core onto the female cavity closing the mould;
- (d) applying a load by means of the tensioning device to the distal portion of the free end and thereby applying a tension to the free end;
- (e) closing the mould by moving the male core relative to the female cavity to advance the male core into the cavity, so that the male core causes the portion of the tensioned free end between the male core and female cavity to move against the load and conform about the male core while the distal portion of the tensioned free end moves with the tensioning device and while the proximal portion is held against the tension;
- and
- (f) injecting plastics material onto the conforming portion of the free end of the indefinite length of core.
Dependencies are inferred from the claim text.