| 摘要 |
983,545. Seaming non-metallic sheet material. UNION CARBIDE CORPORATION. Nov. 13, 1962 [Nov. 14, 1961], No. 42862/62. Heading B5K. [Also in Division B8] A film of thermoplastic material wrapped around a package 10 is heat sealed by bringing the portions of the film to be sealed into contact with one side of a heated porous metal plate 19, applying subatmospheric pressure to the other side of the plate 19, releasing the pressure and cooling the plate 19. A package 10 is wrapped in thermoplastic film by folders 12 and carried by a belt 14 to a wheel 16 having outwardly open sockets 18 to receive the packages 10 in succession. Each socket 18 has porous metal plates 19, such as sintered stainless steel, silver, copper, aluminium or bronze with a porosity range of 20 to 50%. A sintered bronze plate <SP>1</SP>/ 32 inch thick with 35% porosity is preferred. The wheel 16 revolves around a stationary drum 30 around which chambers 25, 26, 27, 28 are disposed. The chambers 25, 26, 27, 28 respectively register with a hot air duct 31 to heat the plates 19 to a temperature of approximately 240‹ F., a suction duct 32 to apply a vacuum of 10 in. Hg to the sockets 18 communicating therewith, a suction duct 33 to apply a vacuum of 30 in. Hg to press the film against the heated surfaces of the plates 19, and a cold air duct 34 to blow cold air through the sockets 18 on to the seals. The cooled sealed packages are discharged on to a belt 36. In a modification, Fig. 4, the package is fed into a heater 38. Heated sintered bronze plates 19, 20 are brought into contact with the package ends. Suction is applied to effect the seal and cold air releases the package. In a further modification (not shown) the sealing plate is heated by resistance heating instead of hot air. In a still further modification. Fig. 6, three sides of each package are sealed by plates 40, 42, 44. To prevent the larger plate 40 reaching a higher temperature than the plates 42, 44 an external shunt 46 to distribute the heat is provided. |
