JP2014231176A - Bag making machine and bag making method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bag making machine and a bag making method which can correct positions of sealing parts and cooling parts by moving the sealing parts and cooling parts through a simple configuration and a simple control method and are easily applicable to existing bag making machines provided with no tensile force application parts in the upstream or the downstream of individual processing parts.SOLUTION: A bag making machine includes a pair of tensile force application parts which are provided each in the upstream and downstream of individual processing parts in the carrying direction of a film W and apply a tensile force to the film W carried by a carrying part and a control part 60 which controls the tensile force application parts to adjust the magnitude of the tensile force to be applied to the film by at least one of the tensile force application part on the basis of the detection information of a detection mark obtained by a mark detection part, more specifically a mark sensor 72, provided between the tensile force application parts in the carrying direction of the film W.

Description

  The present invention relates to a bag making machine and a bag making method for producing a bag body from a belt-like film.

  Conventionally, various types of bag making machines for producing a bag (product) from a film such as a belt-shaped plastic film are known. In a general bag making machine, a belt-like film is fed from a paper feed roll, and the fed film is cut into two at the center position in the width direction by a center blade, and the inner surfaces of the two cut films are separated from each other. It is superimposed in a state of facing each other. At this time, the thermoplastic resin layers in each of the two-layer belt-like films come to face each other.

  Thereafter, various processes are performed by the movable units on the two-layer belt-shaped films that are overlapped, whereby a bag body (specifically, a plastic bag) is manufactured. Specifically, a vertical heat seal plate, a vertical cooling plate, a horizontal heat seal plate, a horizontal cooling plate, and a cutting blade are used as the movable unit, and a bag body is manufactured for each intermittent feed of the film. Here, each movable unit is arrange | positioned at intervals based on a product pitch along the longitudinal direction of a strip | belt-shaped film, and each movable unit can move along the longitudinal direction of a film. Furthermore, the drive mechanism of each movable unit is mounted in the bag making machine, and each movable unit can be moved along the longitudinal direction of the film by the drive mechanism.

  As such a position adjustment method for each movable unit, for example, the one disclosed in Patent Document 1 is conventionally known. In Patent Document 1, a film having a printed pattern repeatedly printed at a constant printing pitch (product pitch) is intermittently conveyed by a length corresponding to the printing pitch, and the film is horizontally sealed at a predetermined position with respect to the printed pattern. In order to prevent the printed pattern and the sealing position from shifting even if the printing pitch fluctuates due to expansion and contraction of the film, the detection mark attached to the film at each printing pitch is marked with an optical sensor or the like. The print position of the printed pattern on the film is detected by detection by the sensor, and the vertical heater, the horizontal heater, the cooling member, the punch and the cutter are moved to a desired position along the longitudinal direction of the film based on the detection information. Technology is disclosed.

JP 2010-105186 A

  However, in the conventional bag making machine as disclosed in Patent Document 1 and the like, each movable unit such as a heater and a cooling member is moved independently to prevent occurrence of seal position deviation and cut position deviation. Since the position of the movable unit is corrected, there is a problem that a drive unit and a position detection unit are required for each movable unit, and the entire apparatus becomes expensive. Moreover, since it is necessary to control the positions of a plurality of movable units at the same time, there is a problem that the control of the entire apparatus becomes complicated.

  The present invention has been made in consideration of such points, and the position of the seal part and the cooling part can be corrected by moving the seal part and the cooling part with a simple configuration and control method. Further, a bag making machine and a bag making method that can easily apply the configuration of the present invention to an existing bag making machine in which no tension applying unit is provided upstream or downstream of each processing unit. The purpose is to provide.

  The bag-making machine of the present invention performs processing on the transport unit that transports the strip-shaped film along the longitudinal direction of the film and the strip-shaped film transported by the transport unit, respectively, along the longitudinal direction of the film. A plurality of processing sections provided on the upstream side and the downstream side of each processing section in the film transport direction, and a pair of tension applying sections for applying tension to the film transported by the transport section, and a film A mark detection unit that is provided between the pair of tension applying units in the conveyance direction and detects a detection mark attached to a belt-like film conveyed by the conveyance unit for each product pitch, and detection by the mark detection unit Based on the detection information of the mark, the tension applied to the film by at least one of the pair of tension applying sections is adjusted. Yo characterized by comprising a control unit for controlling of the tension applying portion.

  According to such a bag making machine, in order to prevent the printed pattern and the sealing position from shifting even if the printing pitch fluctuates due to expansion and contraction of the film or the like, In adjusting the position of the processing unit such as the cooling unit, the film is applied to the film by the tension applying unit provided on the upstream side or the downstream side of each processing unit in the film transport direction based on the detection information of the detection mark by the mark detection unit. The magnitude of the applied tension is adjusted. This eliminates the need to install a drive unit and a position detection unit for each seal unit and cooling unit. For this reason, the seal unit and cooling unit can be moved by a simple configuration and control method. The position of each processing unit such as a unit can be corrected. Further, the above configuration can be easily applied to an existing bag making machine in which no tension applying unit is provided on the upstream side or the downstream side of each processing unit.

  In the bag making machine of the present invention, the tension applying unit includes a dancer roll stretched on a belt-shaped film conveyed by the conveyance unit, and a dancer roll driving unit that drives the dancer roll, The control unit may adjust the position of the dancer roll by controlling the dancer roll driving unit.

  In the bag making machine of the present invention, each of the plurality of processing units is any of a sealing unit that seals a strip-shaped film and a cooling unit that cools the strip-shaped film sealed by the sealing unit Or it may consist of one thing.

  The bag-making method of the present invention is a process for transporting a strip-shaped film along the longitudinal direction of the film, and a strip-shaped film transported by a plurality of processing units provided along the longitudinal direction of the film. Each of the steps of processing, the step of applying tension to the film to be transported at the upstream side and the downstream side of each processing unit in the film transport direction, and the tension of the film to be transported in the film transport direction. And a step of detecting detection marks attached to the film to be transported for each product pitch between the two places to be applied, and based on detection information of the detection marks, each processing unit in the film transport direction It is characterized in that the magnitude of tension applied to the film is adjusted at at least one of the upstream side and the downstream side.

  According to such a bag making method, in order to prevent the printed pattern and the sealing position from shifting even if the printing pitch fluctuates due to expansion and contraction of the film or the like, In adjusting the position of the processing unit such as the cooling unit, the film is given to the film at at least one of the upstream side and the downstream side of each processing unit in the film transport direction based on the detection information of the detection mark. The magnitude of tension is adjusted. This eliminates the need to install a drive unit and a position detection unit for each seal unit and cooling unit. For this reason, the seal unit and cooling unit can be moved by a simple configuration and control method. The position of each processing unit such as a unit can be corrected. Further, the above configuration can be easily applied to an existing bag making machine in which no tension applying unit is provided on the upstream side or the downstream side of each processing unit.

  According to the bag making machine and the bag making method of the present invention, the position of the seal part and the cooling part can be corrected by moving the seal part and the cooling part with a simple configuration and control method. The configuration of the present invention can be easily applied to an existing bag making machine in which no tension applying unit is provided on the upstream side or the downstream side of the unit.

It is a block diagram which shows the whole structure of the bag making machine by embodiment of this invention. It is a perspective view which shows the structure of the dancer roll and dancer roll drive part in the bag making machine shown in FIG. It is a block diagram which shows the whole structure of the conventional bag making machine as a comparative example. It is a block diagram which shows the other whole structure of the conventional bag making machine as a comparative example.

  Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are diagrams showing a bag making machine according to the present embodiment. Among these, FIG. 1 is a block diagram which shows the whole structure of the bag making machine by this Embodiment, and FIG. 2 is a perspective view which shows the structure of the dancer roll and dancer roll drive part in the bag making machine shown in FIG. It is. 3 and 4 are configuration diagrams showing the overall configuration of a conventional bag making machine as a comparative example.

  First, the overall configuration of the bag making machine according to the present embodiment will be described with reference to FIG. As shown in FIG. 1, in the bag making machine according to the present embodiment, a belt-like film W is fed out from a paper feed roll 10. The strip-shaped film W is repeatedly printed with a print pattern with a constant print pitch (product pitch), and a detection mark is provided for each print pitch in the vicinity of the side edge of the film W. Further, the transport direction of the film W fed out from the paper feed roll 10 is changed by an angle of 90 ° by the turn bar 12 (specifically, on the upstream side of the turn bar 12 in the transport direction of the film W). The film W extends in a direction perpendicular to the paper surface of FIG. 1, but the direction of the film W is changed by the turn bar 12 so that it extends along the paper surface of FIG. Thereafter, the film W is continuously conveyed and cut into two at the center position in the width direction by the center blade 14, and the two cut films W are turned again at an angle of 90 ° by the M-shaped plate 16. 1 are overlapped so that the inner surfaces face each other (specifically, the two films W extend upstream of the M-shaped plate 16 in the transport direction of the film W in the direction along the plane of FIG. 1). The conveying direction of each film W is changed by the M-shaped plate 16 and extends in a direction perpendicular to the paper surface of FIG. 1). At this time, the thermoplastic resin layers in each of the two strip-shaped films W face each other.

  Thereafter, the two belt-like films W are superposed, and the two-layer superposed belt-like films W are intermittently conveyed by the front nip roll 20, the intermediate nip roll 22, and the rear nip roll 24. These front-stage nip roll 20, intermediate nip roll 22 and rear-stage nip roll 24 constitute a transport section that intermittently transports the two-layer belt-like film W along the longitudinal direction of the film W. Specifically, after the film W is continuously conveyed by a predetermined amount of movement by the front nip roll 20, the intermediate nip roll 22, and the rear nip roll 24, the operation of stopping the conveyance for a certain period is repeatedly performed.

  In addition, two dancer rolls 26 that are movable in the vertical direction are provided on the upstream side of the front nip roll 20 in the conveyance direction of the film W, and each dancer roll 26 is cut by the center blade 14. After that, they are stretched over the two strip-shaped films W before being superposed. Then, tension is applied to the film W by each dancer roll 26, and thereby alignment in the transport direction of the film W is performed. More specifically, each dancer roll 26 is continuously moved in the vertical direction in FIG. 1, thereby switching the transport mode of the belt-like film W from continuous transport to intermittent transport. ing.

  Further, as shown in FIG. 1, a vertical seal portion 30 is provided between the front nip roll 20 and the intermediate nip roll 22 in the film W conveyance direction. The vertical seal portion 30 is configured to perform sealing at both side edge portions on the two-layered strip-shaped film W in an overlapped state. Specifically, the vertical seal portion 30 includes an elongated heat seal plate (heat seal bar) 32 that performs heat seal on both side edges of the two-layered strip-shaped film W in an overlapped state, and the film W. And a cooling plate (cooling bar) 34 that is provided downstream of the heat seal plate 32 in the conveying direction and cools both side edges where the band-like film W is sealed.

  Further, as shown in FIG. 1, a lateral seal portion 40 is provided between the intermediate nip roll 22 and the rear nip roll 24 in the film W conveyance direction. The horizontal seal portion 40 is configured to seal the two-layered strip-shaped film W in an overlapped state along the width direction. Specifically, the lateral seal portion 40 includes a plurality of heat seal plates (heat seal bars) 42 that seal the two-layered strip-shaped film W in an overlapped state along the width direction, and the film. A cooling plate (cooling bar) 44 is provided on the downstream side of each heat seal plate 42 in the W conveyance direction and cools the film W that has been sealed in the width direction. Further, the heat seal plates 42 and the cooling plates 44 of the horizontal seal portion 40 are positioned so as to be spaced apart in the transport direction of the film W by the print pitch (product pitch) of the printed pattern repeatedly printed on the film W. Is provided. In the present embodiment, the heat-seal plate 42 and the cooling plate 44 are used for the belt-like film W conveyed by the conveyance unit (specifically, the front nip roll 20, the intermediate nip roll 22, and the rear nip roll 24). A plurality of processing units each performing processing is configured.

  Further, a punch portion 80 and a notch portion 82 are provided on the downstream side of the horizontal seal portion 40 in the transport direction of the film W, respectively. The punch unit 80 is configured to punch the two-layered strip-shaped film W sealed by the vertical seal unit 30 and the horizontal seal unit 40 to form punch holes. In addition, the notch portion 82 should be manufactured by notching a two-layer belt-like film W sealed by the vertical seal portion 30 and the horizontal seal portion 40, respectively, so as to produce a notch such as a triangular shape or a linear shape. It is formed near the opening of the bag body. Further, a cutting blade 46 is provided on the downstream side of the rear nip roll 24 in the conveyance direction of the film W, and the two-layer belt-like film W sealed by the vertical seal portion 30 and the horizontal seal portion 40 is as follows. The cutting blade 46 cuts into two at the center position in the width direction and cuts along the width direction. In this way, a bag body (specifically, a plastic bag) W ′ as a product is manufactured.

  In the present embodiment, dancer rolls 50 are provided on the upstream side and the downstream side of each heat seal plate 42 and cooling plate 44 of the lateral seal portion 40 in the transport direction of the film W. A tension is applied to W, and thereby alignment in the transport direction of the film W is performed. These dancer rolls 50 constitute a pair of tension applying sections that apply tension to the film W conveyed by the conveying section. Each dancer roll 50 is moved in the vertical direction in FIG. 1 by a corresponding dancer roll drive unit 52. The structure of such a dancer roll 50 and the dancer roll drive part 52 is demonstrated using FIG.

  As shown in FIG. 2, dancer roll driving units 52 are arranged in the vicinity of both end portions of the dancer roll 50 for one dancer roll 50, and each dancer roll driving unit 52 has a shaft 50 a of the dancer roll 50. The both ends of each are supported and moved up and down. More specifically, each dancer roll drive unit 52 is composed of, for example, a uniaxial cylinder such as a mechanical cylinder, and each dancer roll drive unit 52 is provided with a piston member 52a that moves forward and backward in FIG. Further, each end of the shaft 50a of the dancer roll 50 is connected to the tip (the upper end in FIG. 2) of each piston member 52a. The dancer roll 50 is also moved in the vertical direction by the piston members 52a of the two dancer roll driving units 52 moving in the vertical direction in synchronization. The driving of the dancer roll 50 by each dancer roll driving unit 52 is controlled by a control unit 60 described later.

  As shown in FIG. 1, a mark sensor 70 including a photoelectric tube sensor and a CCD camera is installed on the upstream side of the vertical seal portion 30 in the conveyance direction of the film W, and a detection mark attached to the film W is displayed. The mark sensor 70 detects the mark. Further, a mark sensor 72 composed of a photoelectric tube sensor, a CCD camera or the like is also installed between the two dancer rolls 50 in the transport direction of the film W, and a detection mark attached to the film W is detected by the mark sensor 72. It has become so. Further, a mark sensor 74 composed of a photoelectric tube sensor, a CCD camera, or the like is installed on the downstream side of the horizontal seal portion 40 in the transport direction of the film W, and a detection mark attached to the film W is detected by the mark sensor 74. It has become so.

  Moreover, as shown in FIG. 1, in this Embodiment, the control part 60 which controls each dancer roll drive part 52 is provided. Here, the control unit 60 is also connected to the mark sensor 72, and detection information of the detection mark by the mark sensor 72 is sent to the control unit 60. Then, the control unit 60 controls at least one of the two dancer roll driving units 52 based on the detection information of the detection marks by the mark sensor 72, and corresponds to the dancer roll driving unit 52. The magnitude of tension applied to the film W by the dancer roll 50 is adjusted. More specifically, the control unit 60 calculates the size of the product pitch in the film W based on the detection information of the detection mark by the mark sensor 72 and the movement amount of the film W, and each heat seal plate 42 in the horizontal seal unit 40. Further, by adjusting the amount of tension applied to the film W by the dancer roll 50 so that the distance between the cooling plate 44 and the calculated product pitch is the same, the registration in the transport direction of the film W is adjusted. Align. In general, in a bag making machine, the pitch deviation between adjacent printed patterns in the belt-like film W is generally zero, so that each heat seal plate 42 and cooling plate 44 in the lateral seal portion 40 are independent from other members. Even if the distance between each heat seal plate 42 and the cooling plate 44 is kept constant, the position of the seal in the film W can be simply expanded and contracted by the dancer roll 50 in the longitudinal direction. Generation | occurrence | production of deviation etc. can be prevented.

  In the present embodiment, the control unit 60 controls the dancer roll 50 based on the detection information of the detection marks by the mark sensor 72 as described above, and the heat seal plate 42 and the cooling plate 44 in the horizontal seal unit 40. Either dancer roll 50 of the two dancer rolls 50 provided on the upstream side and the downstream side may be controlled. Alternatively, the control unit 60 uses two dancer rolls 50 provided on the upstream side and the downstream side of the heat seal plate 42 and the cooling plate 44 in the horizontal seal unit 40 based on the detection information of the detection marks by the mark sensor 72, respectively. Both of them may be controlled.

  Next, as a comparative example, FIG. 3 shows an aspect of a conventional bag making machine in which dancer rolls 50 are not installed on the upstream side and the downstream side of each heat seal plate 42 and cooling plate 44 of the lateral seal portion 40. This will be described with reference to FIG.

  In the bag making machine shown in FIG. 3, the dancer roll 50 is provided on the upstream side of each heat seal plate 42 and cooling plate 44 of the horizontal seal portion 40, but downstream of each heat seal plate 42 and cooling plate 44. There is no dancer roll 50 on the side. Further, in the bag making machine as shown in FIG. 1 according to the present invention, the mark sensor 72 is installed on the upstream side of the lateral seal portion 40 in the transport direction of the film W, and the detection mark attached to the film W Although detected by the mark sensor 72, such a mark sensor 72 is not installed in the bag making machine shown in FIG.

  In the bag making machine shown in FIG. 3, in order to prevent the printed pattern and the seal position from shifting even if the printing pitch fluctuates due to expansion and contraction of the film W, based on the detection information of the detection mark by the mark sensor 70, The conveyance of the film W by the front nip roll 20 and the intermediate nip roll 22 is controlled. Thereby, in the sealing process of the film W by the vertical seal | sticker part 30, the position of the printing pattern in the conveyance direction of the film W is adjusted. Further, the cutting position of the film W by the cutting blade 46 is controlled based on the detection information of the detection mark by the mark sensor 74. However, the bag making machine shown in FIG. 3 has a problem in that the position of the printed pattern in the film W conveyance direction cannot be adjusted with high accuracy in the film W sealing process by the horizontal sealing portion 40.

  On the other hand, in the bag making machine shown in FIG. 4, the dancer roll 50 provided on the upstream side of each heat seal plate 42 or cooling plate 44 of the lateral seal portion 40 is compared with the bag making machine shown in FIG. 3. A dancer roll position detection sensor 76 for detecting the position is provided. Further, in the bag making machine shown in FIG. 4, each heat seal plate 42 and cooling plate 44 of the lateral seal portion 40 can move along the longitudinal direction of the film W independently of other members. More specifically, the bag making machine shown in FIG. 4 is provided with a drive mechanism for a plurality of movable units including the heat seal plates 42 and the cooling plates 44. It can be moved along the longitudinal direction (see arrows attached to the heat seal plates 42 and the cooling plates 44 in FIG. 4). In the bag making machine shown in FIG. 4, in order to prevent the printed pattern and the seal position from shifting even if the printing pitch fluctuates due to expansion and contraction of the film W, the dancer roll 50 is detected by the dancer roll position detection sensor 76. Based on the position detection information, the movable units including the heat seal plates 42 and the cooling plates 44 are moved along the longitudinal direction of the film W, and the positions of these movable units are adjusted.

  However, in the bag making machine as shown in FIG. 4, in order to prevent the occurrence of the seal position shift, each movable unit such as each heat seal plate 42 and cooling plate 44 is moved independently to position each movable unit. Since the correction is made, a drive unit and a position detection unit are required for each movable unit, and there is a problem that the entire apparatus becomes expensive. Moreover, since it is necessary to control the positions of a plurality of movable units at the same time, there is a problem that the control of the entire apparatus becomes complicated.

  On the other hand, according to the bag making machine and the bag making method of the present embodiment configured as shown in FIGS. 1 and 2, even if the printing pitch fluctuates due to expansion and contraction of the film W, the printed pattern and the seal In order to prevent the position from deviating, when adjusting the position of each processing section such as each heat seal plate 42 or cooling plate 44 that performs processing on the belt-like film W, the two in the transport direction of the film W Based on the detection information of the detection mark by the mark sensor 72 provided between the dancer rolls 50, the dancer roll 50 provided on the upstream side or the downstream side of each processing unit in the transport direction of the film W gives the film W. The magnitude of tension is adjusted. This eliminates the need to install a drive unit and a position detection unit for each heat seal plate 42 and cooling plate 44. For this reason, each heat seal plate 42 and cooling plate 44 is moved by a simple configuration and control method. The positions of the heat seal plates 42 and the cooling plates 44 can be corrected.

  In particular, in general, in a bag making machine, the pitch deviation between adjacent printed patterns in the belt-like film W is generally zero, so that each heat seal plate 42 and the cooling plate 44 in the lateral seal portion 40 are independent from other members. Even if the distance between each heat seal plate 42 and the cooling plate 44 is kept constant, the position of the seal in the film W can be simply expanded and contracted by the dancer roll 50 in the longitudinal direction. Generation | occurrence | production of deviation etc. can be prevented.

  In addition, the present invention can be easily applied to an existing bag making machine in which the dancer roll 50 is not provided as a tension applying unit on the upstream side or the downstream side of each processing unit such as the heat seal plate 42 or the cooling plate 44. The configuration can be applied. That is, with respect to the existing bag making machine, the dancer roll 50 can be easily installed as a tension applying unit on the upstream side or downstream side of each processing unit such as each heat seal plate 42 or cooling plate 44, Since the mark sensor 72 can be easily installed between the two dancer rolls 50 in the conveyance direction of the film W, the mark sensor 72 can be installed by installing the dancer roll 50 and the mark sensor 72 in an existing bag making machine. Based on the detection information of the detection mark by the sensor 72, the magnitude of tension applied to the film W by the dancer roll 50 provided on the upstream side or downstream side of each processing unit in the transport direction of the film W is adjusted. Will be able to.

  In addition, the bag making machine by this Embodiment is not limited to an aspect as mentioned above, A various change can be added.

  For example, it is provided on the upstream side and the downstream side of each processing unit such as each heat seal plate 42 and cooling plate 44 in the transport direction of the film W, and transport unit (specifically, the front nip roll 20, the intermediate nip roll 22, and the rear stage). The pair of tension applying sections that apply tension to the film W conveyed by the nip roll 24) is not limited to a combination of the dancer roll 50 and the dancer drive section 52. As long as it can apply tension to the film W, a configuration other than the mechanism composed of the dancer roll 50 and the dancer roll driving unit 52 may be used as the tension applying unit.

DESCRIPTION OF SYMBOLS 10 Paper feed roll 12 Turn bar 14 Center blade 16 M-shaped board 20 Front nip roll 22 Intermediate nip roll 24 Rear nip roll 26 Dancer roll 30 Vertical seal part 32 Heat seal plate 34 Cooling plate 40 Horizontal seal part 42 Heat seal plate 44 Cooling plate 46 Cutting blade 50 Dancer Roll 50a Shaft 52 Dancer Roll Drive 52a Piston Member 60 Control 70 Mark Sensor 72 Mark Sensor 74 Mark Sensor 76 Dancer Roll Position Detection Sensor 80 Punch 82 Notch W Film W ′ Bag

Claims (4)

A transport unit for transporting the belt-shaped film along the longitudinal direction of the film; and
A plurality of processing units provided along the longitudinal direction of the film, each performing processing on the belt-shaped film transported by the transport unit;
A pair of tension applying units provided on the upstream side and the downstream side of each processing unit in the film transport direction, respectively, for applying tension to the film transported by the transport unit;
A mark detection unit that is provided between the pair of tension applying units in the conveyance direction of the film and detects a detection mark attached to the belt-shaped film conveyed by the conveyance unit for each product pitch;
Based on the detection information of the detection mark by the mark detection unit, the tension applying unit is controlled to adjust the magnitude of the tension applied to the film by at least one of the pair of tension applying units. A control unit;
A bag making machine.   The tension applying unit includes a dancer roll stretched on a belt-shaped film conveyed by the conveying unit, and a dancer roll driving unit that drives the dancer roll, and the control unit includes the dancer roll driving unit. The bag making machine according to claim 1, wherein the position of the dancer roll is adjusted by control.   Each of the plurality of processing units includes any one of a sealing unit that seals a band-shaped film and a cooling unit that cools the band-shaped film sealed by the sealing unit. The bag making machine according to 1 or 2. A step of conveying the belt-like film along the longitudinal direction of the film;
A process of processing each of the strip-shaped films to be conveyed by a plurality of processing units provided along the longitudinal direction of the film;
A step of applying tension to the film to be conveyed at the upstream side and the downstream side of each processing unit in the film conveyance direction;
A step of detecting a detection mark attached to each film pitch on the film to be transported between two locations that apply tension to the film to be transported in the film transport direction;
With
A bag making method of adjusting a magnitude of tension applied to a film at at least one of an upstream side and a downstream side of each processing unit in a film conveyance direction based on detection information of a detection mark.

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