JP3302488B2 - Bag making machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bag making machine for producing plastic bags.

[0002]

2. Description of the Related Art In a bag making machine for producing a plastic bag, a continuous plastic film is superimposed on a plurality of layers, and this is intermittently fed in the length direction. The plastic film is heat sealed. Normally, a plastic film is heat-sealed parallel to its feed direction, and a vertical seal is formed on the plastic film.
At the same time, the plastic film is heat-sealed at right angles to the feed direction to form a horizontal seal portion in the plastic film. Further, the plastic film is fed to the slit blade, and the plastic film is slit at the center position of the vertical seal portion in parallel with the feeding direction. Thereafter, the plastic film is fed to the cutter, and the plastic film is cut by the cutter every time the plastic film is intermittently fed, and the plastic film is cut at right angles to the feeding direction near the horizontal seal portion. This produces a plastic bag.

Prior to the filing of the present application, the applicant has
No. 197124 has developed and proposed a bag making machine. In the bag making machine disclosed in the publication, as shown in FIG. 3, before cutting the plastic film 1, the plastic film 1 is punched by a punching tool at the intersection of the vertical seal portion and the horizontal seal portion, and the plastic film 1 is cut out. Hole 2 is formed. Thereafter, the plastic film 1 is cut by the cutter at the center position P0 of the punched hole 2, whereby the plastic bag is corner-cut. However, the plastic film 1 is not always cut at the center position P0 of the punched hole 2, and the cut position is shifted from the center position P0 of the punched hole 2, and a projecting step may be generated at a corner cut portion of the plastic bag. Based on this, in the bag making machine of the same publication, every time the plastic film 1 is intermittently fed, while the plastic film 1 is heat-sealed by the heater,
The cutter is driven twice, and as shown in FIG. 4, first, the plastic film 1 is cut by the cutter at a cutting position P1 downstream of the center position P0. Thereafter, the cutter was moved in the direction opposite to the feed direction X of the plastic film 1 and displaced by a small distance L, and the plastic film 1 was cut again at the cutting position P2 upstream of the center position P0. Therefore, the center position P0
The plastic film 1 is cut on both sides of the plastic bag, and no projecting step occurs at the corner cut portion of the plastic bag.

In short, in the bag making machine disclosed in the above publication, the heater is driven only once, the plastic film 1 is heat-sealed only once, and the cutter is driven twice, every time the plastic film 1 is intermittently fed. The film 1 was cut twice. As for the heater and the cutter, an appropriate drive motor is used as a drive mechanism, the drive motor and the heater are connected by a crank and a link, and the drive motor and the cutter are connected by a crank and a link. Accordingly, the heater and the cutter are driven by the crank and the link, and the heater rises and falls along the characteristic curve A, and the cutter rises and falls along the characteristic curve B, as shown in FIG.

Further, the plastic film 1 is fed by a film feed mechanism, and the speed V of the plastic film 1 increases to a set value V1. When the plastic film 1 is being fed, the heater descends toward the plastic film 1, and when the plastic film 1 stops, the heater comes into contact with the plastic film 1 and the plastic film 1 is heat-sealed by the heater. . Therefore, the plastic film 1 is fed at a certain time T1, and thereafter, the plastic film 1 is heat-sealed at the same time T2. further,
Within the heat sealing time T2, the cutter descends twice, comes into contact with the plastic film 1, and the plastic film 1 is cut twice. Further, after the first cutting of the plastic film 1 and before the next cutting, the cutter moves away from the plastic film 1 and moves in a direction opposite to the feeding direction X of the plastic film 1 during the rising time T3, Small distance L
Only displace.

However, in order to provide the heater and the cutter with drive characteristic curves A and B having different periods, to drive the heater only once for each intermittent feed of the plastic film 1 and to drive the cutter twice, it is necessary to use the heater. In addition to the driving motor for driving, it is necessary to specially provide a driving motor for driving the cutter. The heater and the cutter cannot be driven by a common drive motor, and the cost is high. Moreover, plastic film 1
Within the heat sealing time T2, the cutter must be lowered twice, and the cutter must be raised and lowered at a high speed. Therefore, it is necessary to use a motor having a large capacity as the drive motor, and the cost is high. Further, when the cutter is moved, a drive motor is used as a moving mechanism thereof, and when the cutter is moved by the drive motor, after the first cutting of the plastic film 1 and before the next cutting, within a short time T3,
The drive motor must move the cutter, which must be moved at a high speed. For this reason, it is necessary to use a large-capacity motor for the drive motor, which is costly. When the cutter is moved at a high speed, vibrations are generated thereby, and the cutting positions P1 and P2 are likely to shift. There is also a problem that the cutter is easily damaged and its life is short.

[0007]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a method for heating a plastic film with a heater and cutting the plastic film with a cutter every time the plastic film is intermittently fed. Using a common drive motor as a mechanism, cutting the plastic film twice at different cutting positions for each intermittent feed of the plastic film, and eliminating the need to drive and move the cutter at high speed. It was made for the purpose of.

[0008]

According to the present invention, the heater is driven twice for each intermittent feeding of the plastic film,
The plastic film is heat sealed twice. Furthermore, every time the plastic film is intermittently fed,
The cutter is synchronized with the heater and is driven twice, the plastic film is cut twice, and after the first cutting of the two cuttings of the plastic film, before the next cutting, the cutter moves in the feeding direction of the plastic film. It moves in the opposite direction and is displaced by a small distance.

After the first cutting of the plastic film, before the next cutting, instead of moving the cutter, a small amount of the plastic film may be fed.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below.
FIG. 1 shows an embodiment of the present invention. In this embodiment, a common drive motor is used as a drive mechanism for the heater and the cutter, the drive motor and the heater are connected by a crank and a link, and the drive motor and the cutter are connected by a crank and a link. The drive motor comprises a servomotor. Therefore, the heater is driven by the crank and the link, and the heater moves up and down along the characteristic curve A ′. At the same time, the cutter is driven by the crank and the link, and the cutter moves up and down along the characteristic curve B ′ in synchronization with the heater. In addition,
Drive motor and heater are linked by crank and link
Tying is known. For example, Japanese Patent Application Laid-Open No. 5-229
No. 008 discloses a related configuration.

Further, the continuous plastic film 1 is superimposed on a plurality of layers, which are intermittently fed in the longitudinal direction. In this embodiment, a servo motor is used as a film feed mechanism, and the plastic film 1 is fed by the servo motor, and its speed V 'increases to a set value V1'. The heater is driven by the servo motor every time the plastic film 1 is intermittently fed, and the plastic film 1 is heat-sealed by the heater. At the same time, each time the plastic film 1 is intermittently fed, the cutter is driven by the servo motor, and the plastic film is cut by the cutter.

The plastic film 1 is heat-sealed parallel to the feeding direction and heat-sealed at right angles to the feeding direction. Therefore, the vertical seal portion and the horizontal seal portion are formed on the plastic film 1 as in the case of the bag making machine disclosed in the above-mentioned publication. The plastic film 1 is fed to the slit blade, and at the center position of the vertical seal portion, the plastic film is slit in parallel with the feeding direction, and at the intersection area between the vertical seal portion and the horizontal seal portion,
The holes 2 are formed in the plastic film 1 in the same manner as in the bag making machine disclosed in the above publication. Thereafter, the plastic film 1 is sent to the cutter, and the plastic film 1 is cut by the cutter. The plastic film 1 is cut at right angles to the feeding direction.

In this bag making machine, the heater is driven twice for each intermittent feeding of the plastic film 1, and the plastic film 1 is heat-sealed twice. Therefore, first, the plastic film 1 is fed for a certain time T1 ', and thereafter, the plastic film 1 is heat-sealed for the same time T2'. Further, after the same time T3 'has elapsed, the plastic film 1 is heat-sealed at the same time T4'. At the same time, plastic film 1
At every intermittent feed, the cutter is synchronized with the heater, driven twice, and the plastic film 1 is cut twice.

Further, regarding the first cutting position of the two cuttings of the plastic film 1, the cutter is arranged at a position P1 downstream of the center position P0 of the punched hole 2, and a cutting position P1 downstream of the center position P0. In, the plastic film 1 is cut by the cutter. Then, after the first cutting, before the next cutting, the cutter moves away from the plastic film 1 and the cutter is operated by the cutter moving mechanism during the rising time T3 ′, and the cutter is moved in the opposite direction to the feeding direction X of the plastic film 1. And is displaced by a small distance L. Therefore, at the next disconnection,
At the cutting position P2 upstream of the center position P0, the plastic film 1 is cut again. Therefore, the plastic film 1 is cut on both sides of the center position P0, and no projecting step occurs at the corner cut portion of the plastic bag. Thereafter, the cutter is operated by the cutter moving mechanism, and the cutter moves to the original position and waits. In this embodiment, a driving motor is used as a cutter moving mechanism, and the cutter is operated and moved by the driving motor. The drive motor comprises a servomotor.

Therefore, in this bag making machine, the cutter only needs to be synchronized with the heater, and a common drive motor can be used as a drive mechanism for the heater and the cutter. Even if a common drive motor is used, the plastic film 1
At the cutting positions P1 and P2 downstream and upstream of the center position P0 for each intermittent feed of
Can be cut many times. There is no need to provide a drive motor for driving the cutter in addition to the drive motor for driving the heater, and the cost is low. Further, when the plastic film 1 is heat-sealed twice, the cutter may be lowered twice and the plastic film 1 may be cut twice within the time T2 ′ to T4 ′, and the cutter may be moved at a high speed. There is no need to raise and lower. It is only necessary to raise and lower the cutter at a low speed, and it is not necessary to use a large-capacity drive motor. Furthermore, after the first cutting of the plastic film 1 and before the next cutting, a relatively long time T
In 3 ', the cutter may be moved by the drive motor, and it is not necessary to move the cutter at high speed. It is sufficient to move the cutter at a low speed, and it is not necessary to use a large-capacity motor for the drive motor, and the cost is low. Moreover, the cutter does not vibrate and the cutting positions P1 and P2 do not shift. There is no problem that the cutter is easily damaged and its life is short.

FIG. 2 shows another embodiment. Also in this embodiment, of the first cutting of the two cuttings of the plastic film 1, the cutting position P1 downstream of the center position P0 is used.
In, the plastic film 1 is cut by the cutter. Then, after the first cutting, before the next cutting, the plastic film 1 is fed by the film feeding mechanism in place of the movement of the cutter during the rising time T3 ', where the cutter separates from the plastic film 1. The speed is kept at the minute speed V2 ', the time is kept at the minute time T5', and the plastic film 1 is fed by a minute amount. Therefore, at the time of the next cutting, the plastic film 1 is cut again at the cutting position P2 upstream of the center position P0. Therefore, the plastic film 1 is cut on both sides of the center position P0, and no projecting step occurs at the corner cut portion of the plastic bag. Therefore, in this case, there is no need to move the cutter, and there is no need to provide a cutter moving mechanism.

[0017]

As described above, according to the present invention, a common drive motor is used as a drive mechanism for the heater and the cutter. The film 1 can be cut twice. There is no need to provide a drive motor for driving the cutter in addition to the drive motor for driving the heater, and the cost is low. There is no need to drive and move the cutter at a high speed, and it is sufficient to drive and move the cutter at a low speed, and it is not necessary to use a large capacity drive motor. Moreover, the cutter does not vibrate and the cutting positions P1 and P2 do not shift. There is no problem that the cutter is easily damaged and its life is short.

[Brief description of the drawings]

FIG. 1 is a graph showing an embodiment of the present invention.

FIG. 2 is a graph showing another embodiment.

FIG. 3 is an explanatory view showing a hole of a plastic film.

FIG. 4 is an explanatory view showing a cutting position of a plastic film.

FIG. 5 is a graph showing characteristics of a conventional bag making machine.

[Explanation of symbols]

 1 Plastic film A 'Driving characteristic curve of heater B' Driving characteristic curve of cutter V 'Feeding speed of plastic film

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B31B 1/14 B29C 65/74 B31B 23/14 B29L 22:00

Claims (2)

(57) [Claims] 1. A continuous plastic film of a plurality of layers is intermittently fed in its length direction, and the plastic film is heat-sealed by a heater and cut by a cutter every time the plastic film is intermittently fed; Thus, in a bag making machine for manufacturing a plastic bag, the heater is driven twice, the plastic film is heat-sealed twice, and the cutter is synchronized with the heater every time the plastic film is intermittently fed. A heater and a cutter driving mechanism that is driven twice and cuts the plastic film twice; and, among the two cuts of the plastic film, after the first cut, before the next cut, the cutter is connected to the plastic film. Opposite to the feed direction of Is moved in a direction, bag making machine, characterized in that a cutter moving mechanism for displacing minute distance. 2. A continuous plastic film of a plurality of layers is intermittently fed in the length direction thereof, and the plastic film is heat-sealed by a heater and the plastic film is cut by a cutter every time the plastic film is intermittently fed; Thus, in a bag making machine for manufacturing a plastic bag, the heater is driven twice, the plastic film is heat-sealed twice, and the cutter is synchronized with the heater every time the plastic film is intermittently fed. A heater and a cutter driving mechanism that is driven twice and cuts the plastic film twice; and, among the two cuts of the plastic film, after the first cut and before the next cut, the plastic film is cut by a minute amount. Only send film Bag making machine, characterized in that a mechanism.