Apparatus for heat sealing two superposed layers of plastic film

• US 5,540,802 A
• Filed: 05/02/1994
• Issued: 07/30/1996
• Est. Priority Date: 10/09/1991
• Status: Expired due to Term

• Current Assignee: Totani Giken Kogyo Company Limited
• Original Assignee: Totani Giken Kogyo Company Limited
• Inventors: Totani, Mikio
• Primary Examiner(s): Barry, Chester T.
• Application Number:
  US08/236,687
• Time in Patent Office: 820 Days
• Field of Search: 156/359, 493/8, 493/10, 53/51, 53/64, 53/75
• US Class Current: 156/359
• CPC Class Codes: B29C 65/18 using heated tools
• CPC Class Codes: B29C 65/7891 of discontinuously moving sheets or webs
• CPC Class Codes: B29C 66/1122 Single lap to lap joints, i.e. overlap joints B29C66/45, B29C66/472, B29C66/52272 take precedence
• CPC Class Codes: B29C 66/43 Joining a relatively small portion of the surface of said articles B29C66/45 takes precedence
• CPC Class Codes: B29C 66/81465 one placed behind the other in a single row in the feed direction
• CPC Class Codes: B29C 66/8221 Scissor or lever mechanisms, i.e. involving a pivot point
• CPC Class Codes: B29C 66/8225 Crank mechanisms
• CPC Class Codes: B29C 66/8322 Joining or pressing tools reciprocating along one axis
• CPC Class Codes: B29C 66/93441 the speed being non-constant over time
• CPC Class Codes: B29C 66/93451 by controlling or regulating the rotational speed, i.e. the speed of revolution
• CPC Class Codes: B29C 66/9392 in explicit relation to another variable, e.g. speed diagrams
• CPC Class Codes: B29C 66/944 by controlling or regulating the time
• CPC Class Codes: B29C 66/9592 in explicit relation to another variable, e.g. X-Y diagrams
• CPC Class Codes: B29C 66/96 characterised by the method for implementing the controlling of the joining process
• CPC Class Codes: B29L 2031/7128 Bags, sacks, sachets tea bags B29L2031/7122; medical bags B29L2031/7148
• CPC Class Codes: B31B 2150/002 by joining superimposed sheets, e.g. with separate bottom sheets
• CPC Class Codes: B31B 70/946 the bags being interconnected

Abstract

An apparatus for heat sealing two superposed layers of plastic film, in which movable sealing bar means are disposed opposite to fixed sealing bar means so that the layers of the plastic film are intermittently passed between the movable and fixed sealing bar means. The movable sealing bar means is reciprocatingly moved whenever the plastic film layers are intermittently fed. The layers of plastic film are sandwiched between and heat sealed by the movable and fixed sealing bar means when temporarily stopped. The feeding speed for the layers of plastic film, the feeding time for the layers of plastic film, the driving speeds of the movable sealing bar drive means and the heat sealing time for the layers of plastic film are computer controlled. The computer is programmed so that a waiting time can be inserted between the plastic film feeding time and the plastic film heat sealing time. Accordingly, the plastic bag making speed can be optionally lowered without changing the length of the plastic bag and heat sealing condition.

Claims

1. An apparatus for heat sealing two superposed layers of plastic film, including fixed sealing bar means, movable sealing bar means disposed opposite to said fixed sealing bar means, the layers of plastic film being passed between said movable and fixed sealing bars, plastic film intermittently feeding means including a second servo motor operatively connected to feed roller means which is rotated by said second servo motor for intermittently feeding the layers of plastic film for a length, the layers of plastic film being temporarily stopped whenever intermittently fed, and movable sealing bar drive means including a first servo motor operatively connected to crank means which is rotated by said first servo motor for reciprocatingly moving said movable sealing bar means whenever the layers of plastic film are intermittently fed, between a first position in which said movable sealing bar means is advanced toward said fixed sealing bar means so that the layers of plastic film are sandwiched between said movable and fixed sealing bar means, and a second position in which said movable sealing bar means is retracted and spaced from said fixed sealing bar means and the layers of plastic film, the layers of plastic film being sandwiched between and heat sealed by said movable and fixed sealing bar means when temporarily stopped, said apparatus comprising a computer connected to said first and second servo motors, said computer being programmed to control operation of said first and second servo motors so that the layers of plastic film are intermittently fed at a feeding speed V0 for a feeding time T1 and said crank means is rotated and maintained at a first speed V1 to heat seal said layers of plastic film for a heat sealing time T2 and then temporarily accelerated or decelerated to a second speed V2, said computer being further programmed so that a waiting time T4 can be inserted between said plastic film feeding time T1 and said plastic film heat sealing time T2 to thereby change the cycle time T3 of the apparatus, said feeding speed V0 and said feeding time T1 being automatically determined by said computer in accordance with the parameters which are selected by an operator and input to said computer, said parameters including the feed length of the layers and the acceleration rate from 0 to said feeding speed V0, said first speed V1 being automatically determined by said computer in accordance with said sealing time T2 which is selected by the operator and input to said computer, said second speed V2 being automatically determined by said computer in accordance with the sum of said feeding time T1 and said waiting time T4, said waiting time T4 being selected by the operator and input to said computer.

2. An apparatus as set forth in claim 1, wherein said movable sealing bar drive means comprises rocker means operatively connected to said movable sealing bar means, said crank means being operatively connected to said rocker means, said rocker means being rocked by said crank means which is rotated by said servo motor so that said movable sealing bar means is reciprocatingly moved by said rocker means.

3. An apparatus as set forth in claim 2, wherein the rotating angle of said crank means is simulated by said computer.