Apparatus for compression molding of retroreflective sheeting
First Claim
1. In apparatus for continuously embossing synthetic thermoplastic sheeting to generate precisely formed embossments on one surface thereof, the combination comprising:
- A. a frame;
B. an elongated member mounted for movement in a path along said frame;
C. a series of at least three presses mounted on said frame along said path, each press having a first platen in spaced relationship to the upper surface of said elongated member and a second platen disposed in spaced relationship to the other surface of said elongated member, said presses being equally spaced, center-to-center, a predetermined distance along said path, said presses being operable to move at least one of said platens towards the other to a closed position and away from the other to an open position;
D. means for indexing said elongated member along said path a distance equal to said predetermined distance of spacing of said presses;
E. means for operating all of said presses to open and close said platens, respectively, prior to, and subsequent to said indexing; and
F. means connected to said presses for controlling the temperature of at least one of said platens of at least some of said presses along said path.
2 Assignments
0 Petitions
Accused Products
Abstract
There are disclosed an apparatus and a method for continuously embossing synthetic plastic sheet material with precisely formed embossments in patterns repeating along the length thereof. The apparatus includes a movable polished belt upon which the sheet material is carried, and a series of molds are placed on the sheet material. As the sheet material and molds are advanced in steps through the apparatus, presses clamp the molds and belt against opposite surfaces of the sheet material and raise the temperature of the assembly to embossing temperature for the resin to cause the resin to flow into the mold cavities, and volatiles at the interface are dissolved in the resin. After the embossing step, the clamping pressure is released and this permits limited shrinkage of the mold and sheet material. At subsequent stations, controlled temperature reduction is effected, and limited shrinkage is permitted after the clamping pressure is released at each station and as the material and molds move to the next station. Mold distortion is thus avoided and the embossments remain precisely formed.
141 Citations
16 Claims
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1. In apparatus for continuously embossing synthetic thermoplastic sheeting to generate precisely formed embossments on one surface thereof, the combination comprising:
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A. a frame; B. an elongated member mounted for movement in a path along said frame; C. a series of at least three presses mounted on said frame along said path, each press having a first platen in spaced relationship to the upper surface of said elongated member and a second platen disposed in spaced relationship to the other surface of said elongated member, said presses being equally spaced, center-to-center, a predetermined distance along said path, said presses being operable to move at least one of said platens towards the other to a closed position and away from the other to an open position; D. means for indexing said elongated member along said path a distance equal to said predetermined distance of spacing of said presses; E. means for operating all of said presses to open and close said platens, respectively, prior to, and subsequent to said indexing; and F. means connected to said presses for controlling the temperature of at least one of said platens of at least some of said presses along said path. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. In apparatus for continuously embossing synthetic thermoplastic sheeting to generate precisely formed embossments on one surface thereof and a smooth opposite surface, the combination comprising:
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A. a frame; B. an elongated polishing member mounted in said frame for movement in a path along said frame and having a highly polished upper surface; C. a series of mold members overlying the polished surface of said polishing member and adapted to emboss an associated length of synthetic plastic sheet material disposed between said molds and said polishing member, said molds being equally spaced, on center, along said path a predetermined distance; D. a series of at least three presses mounted in said frame along said path, each press having a first platen in spaced relationship to said polished surface of said polishing member and a second platen disposed in spaced relationship to the other surface of said polishing member, said presses being equally spaced, center-to-center, along said path a distance substantially equal to the spacing of said mold members, said presses being operable to move at least one of said platens towards the other to a closed position and away from the other to an open position, said platens in said closed position clamping the polishing member and molds tightly on opposite surfaces of the associated sheet material to effect embossment thereof;
p1 E. means for indexing said polishing member along said path a distance substantially equal to said spacing to advance the associated sheet material and said molds from press to press;F. means for operating said presses to open said platens to release the clamping force on said polishing member and molds and to close said platens upon completion of the indexing movement to restore said clamping force; and G. means connected to said presses for controlling the temperature of at least one of said platens of at least some of said presses along said path to effect temperature control of said molds as they are indexed from press to press. - View Dependent Claims (12, 13, 14, 15, 16)
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Specification