Patent GB-639411-A (GB)
Title: Improvements in or relating to method and machine for production of multiple packages of plastic material for various products
IPC: B65B11/54
Filed: 1947-06-27
Abstract: 639,411. Moulding sheets of polyvinyl chloride &c. NICOLLE, C. June 27, 1947, No. 17038. Convention date, June 18, 1946. [Class 87 (ii)] [Also in Group XVII] A method for manufacturing multi-cellular packages from a pair of thin sheets of plastic material consists in forming recesses in at least one of the sheets by means of a combination of punches and dies, simultaneously expelling the air from that face of each sheet which is opposite the face engaged by a punch so as to retain the shaped-sheet within the die by suction, thereafter charging the recesses and finally closing the package by the recess-forming dies. In the construction shown in Fig. 2 the press comprises a fixed plate 2 supported by three or more pillars 3 from a base plate (not shown), and a movable plate 4 having a plunger 5 operable manually or by hydraulic or pneumatic means. The plates 2, 4 carry dies 61, 6 which co-operate with a stamping plate 11 which may be similar to that described in Specification 638,135. The plate 11 is pivotally mounted on one of the pillars 3 with freedom for relative vertical sliding movement relative thereto, and carries punches 14, 141 and blank-pressing plates 17, 171. In the operative position, as regards pivotal movement, of the plate 11 (as shown), the punches 14, 141 are in alignment with corresponding recesses in the dies 6, 61. The recesses are closed at their inner ends by plates 8, outwardly urged by springs 9 into substantially air-tight engagement with annular shoulders formed in the recesses. The plate 11 is heated by means not shown and the dies are heated by elements 10. In operation, two flat blanks of polyvinyl chloride are laid respectively on the lower die 6 and the upper punches 141. The plunger 5 is moved upwardly to the position shown, so that recesses are pressed' in the blanks and the portions which remain flat are held by the plates 17, 171, which are driven inwardly relative to the plate 11 against the action of springs 22. The plates 4 and 11 are then moved downwardly and the plate 11 is swung clear of the dies 6, 6<SP>1</SP>. The recesses formed in the lower blank f are filled with respective tablets and the plate 4 is then moved upwardly to bring the unrecessed portions of the two blanks into contact, with pressure and consequent sealing. The blanks are prevented from springing out from the dies into a partly flat condition by the action of atmospheric air pressure acting on the blanks from the outside against the vacuum produced between the blanks and the plates 8 due to air expelled between the plates and their annular sealing shoulders during operation of the punches. Alternatively air may be evacuated from the recesses in any known manner. A duct (not shown) is formed in each punch leading from the horizontal operative face of the punch to atmosphere. A flat headed plate may be provided between the blank and the respective member 17 or 171 in order to hold the blank against the die during the suction operation. Alternatively to the punches 14, 14<SP>1</SP> the blanks may be forced into the die recesses by pneumatic means. In order to prevent air passing to the recesses from the edge of the blank, a projecting strip 25, Fig. 4, may be mounted on the member 17 which presses the marginal portion of the blank into a recess 26 formed between the edge of the die 6 and a member 26a resiliently urged by springs against the side of the die. A corresponding member 26a and strip 25 are provided for the upper plate 17<SP>1</SP> and die 61. Each member 26a has a laterally-extending arm having a projection 31. In operation of the arm 27, on the first upward movement of the plate 4, a beaded edge is formed on the blank f by the action of the member 25 and the recess 26. The pressure of the member 27 due to springs 30 acting on the beaded edge, prevents the marginal portion of the blank from lifting on separation of the plate 17 and die 6. When the blanks 6, 61 are brought into the sealing position the two projections 31 mutually engage and cause the member 27 to release the beaded portions of the blanks f. Means for feeding tablets to the lower recessed sheet are described (see Group XVII). Specification 629,957, [Group XVII], also is referred to.