JP2001354210A - Sealing method, sealing apparatus and bag body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-sealing method which is free from any peeling of the seal when the sealing is started or any generation of defects attributable to generation of the storage of plastics and capable of implementing the uniform sealing before the sealing is completed after the sealing is started. SOLUTION: In this sealing method in which a pair of two seal rolls 55a and 55b are rotated in the opposite direction to each other so that at least one pair of seal bars 57 protruded from side surfaces of the individual seal rolls 55a and 55b intermittently hold a plurality of overlapped heat-bonding films 54, and the films 54 held between the seal bars 57 are sealed by the heat applied to the films 54 via the seal bars 57, the calorie applied to the films 54 via the seal bars 57 during the sealing is gradually reduced so that the calorie is maximized when the sealing is started, and minimized when the sealing is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing method and a sealing device for sealing a resin film, and a bag manufactured by the sealing method. More particularly, the present invention relates to a sealing method and a sealing device capable of imparting sufficient sealing strength by appropriately applying a horizontal seal in an automatic filling and bag making machine, and a bag body to which a horizontal seal is applied by this method.

[0002]

2. Description of the Related Art Bags for packaging contents such as foods and medicines are manufactured using a resin film having heat-fusibility or a film in which a paper layer or an aluminum layer is laminated thereon. .

In order to form a bag while filling the above-mentioned film with contents, a filling bag making machine 5 shown in FIG.
0 is used. In FIG. 4, reference numerals 51a, 51
b is a vertical seal roll, and vertical seal rolls 51a, 51b
Includes a pair of left and right parallel shafts 52 and seal rings 53 provided at both ends thereof, each containing a heater. The seal rings 53 of the vertical seal rolls 51a and 51b oppose each other on their outer peripheral surfaces, and the two films 5 superposed between the opposing seal rings 53.
4 are held at both ends.

Below the vertical seal rolls 51a and 51b, a pair of left and right parallel horizontal seal rolls (seal rolls) are provided.
55a and 55b are arranged. Each of the horizontal seal rolls 55a and 55b includes a roll body 56 and a roll body 5
6, a plurality (three in the figure) of seal bars 57 projecting at equal intervals along the circumferential direction of the roll main body 56 and having a built-in heater. These seal bars 57
Is extended in the axial direction of the roll body 56,
When the horizontal seal rolls 55a and 55b are rotated as described later, the film 54 is intermittently held between the opposing seal bars 57.

The above-mentioned pair of vertical seal rolls 51a, 51
b and the horizontal seal rolls 55a and 55b are driven to rotate in opposite directions in synchronization with the downward movement of the film 54 inserted between the seal rolls 51a, 51b, 55a and 55b from above. That is, the vertical seal roll 51a
The vertical seal roll 51b and the horizontal seal roll 55b are rotated so as to rotate rightward in the drawing.
Are driven to rotate to the left in the figure.

Reference numeral 58 denotes a nozzle for supplying the contents. The nozzle 58 is inserted between the two films 54 from above. The tip of the nozzle 58 is located between the installation position of the vertical seal rolls 51a and 51b and the horizontal seal rolls 55a and 55b. It opens in the middle of the installation position.

The film 54 is processed by the bag making machine 50 into a bag 61 filled with contents. The steps are described below. The two films 54 inserted between the vertical seal rolls 51a and 51b from above are the vertical seal rolls 51a and 51b.
a and 51b, and both ends of the film 54 are sandwiched between the opposing seal rings 53 of the vertical seal rolls 51a and 51b. As a result, the two films 54
Seal (longitudinal seal) formed along the longitudinal direction by heat applied from the seal ring 53
Is formed.

[0008] The film 54 after the vertical sealing is inserted between the horizontal sealing rolls 55a and 55b.
a and 55b through the process shown in FIG. 5, and as a result, a horizontal seal portion 54B is formed on the film 54 so as to cross the film 54.

FIG. 5 illustrates a change in the positional relationship of the seal bar 57 due to the formation of the horizontal seal portion 54B. In the drawing, an arrow C indicates the rotational direction of the horizontal seal rolls 55a and 55b. The pair of seal bars 57 approach each other at a position indicated by 57 (α) in FIG. And 57 (β)
After passing through the position indicated by, it reaches the position indicated by 57 (γ), and thereafter separates from each other. The film 54 has a reference numeral 57
Reference numeral 57 (γ) from the position indicated at (α) (at the start of sealing)
In the position (at the end of the seal) indicated by, the seal is sealed by the heat applied from the seal bar 57 while being sandwiched between the opposing seal bars 57. As a result, the opposing films 54 are thermally fused to each other. As a result, the horizontal seal portion 54
B is formed.

Further, with the formation of the horizontal seal portion 54B, the contents from the nozzle 58 are passed between the two films 54 located above the horizontal seal rolls 55a and 55b (the position indicated by the symbol A in FIG. 4). Supplied. The contents are filled in spaces formed between the two films 54 and sealed on the sides and the lower part by the vertical seal part 54A and the horizontal seal part 54B, respectively.

By rotating the horizontal seal rolls 55a and 55b by a predetermined angle (1/3 rotation in the figure) from the position indicated by the symbol A, the film 54 moves downward and the contents are filled. The upper portion of the film 54 is sandwiched between the adjacent seal bars 57. As a result, the horizontal seal portion 54B is similarly formed at the position sandwiched by the seal bar 57, and the contents are hermetically sealed in the space surrounded by the seal portions 54A and 54B, as shown by reference numeral B in FIG. Is done. Furthermore, the bag body 61 is completed by cutting the center of the horizontal seal portion 54B with a cutter (not shown).

[0012]

In the bag body 61 formed by the above-described conventional bag making machine 50, the lateral seal portion 54B
Of these, there is a problem that the seal strength of the portion formed at the start of the seal (the position indicated by the reference numeral 57 (α) in FIG. 5) tends to be insufficient, and the seal peels easily. . The reason is that at the start of sealing, the film 54 is not heated, so that the temperature difference between the film 54 and the seal bar 57 is large, and as a result, the amount of heat applied from the seal bar 57 to the horizontal seal portion 54B is insufficient. It is considered that the resin in the horizontal seal portion 54B is not sufficiently melted.

On the other hand, in a portion of the horizontal seal portion 54B formed at the end of the seal (the position indicated by reference numeral 57 (γ) in FIG. 5), the molten resin is squeezed by the seal bar 57 and pushed upward. In addition, a phenomenon that a so-called “poly pool” occurs between the two films 54 is often observed. Further, this poly pool is formed by the horizontal seal roll 55.
Due to the mechanical accuracy of a, 55b, etc., it may be formed unevenly. FIG. 6 is a diagram showing a state in which a poly pool 70 biased in the lateral seal portion 54B has occurred.

In the vicinity of the poly pool 70, the molten resin is extruded toward the poly pool 70, so that a thin portion (edge) 71 is formed in the horizontal seal portion 54B. At the edge 71, the mechanical strength of the horizontal seal portion 54B decreases, and stress tends to concentrate more easily than other portions, which may cause a defect such as film breakage.
When the uneven poly pool 70 as shown in FIG. 1 occurs, a defect due to the formation of the edge 71 tends to occur. The cause of the occurrence of the poly pool 70 and the edge 71 is as follows.
At the end of the seal, the horizontal seal portion 54B is already sufficiently heated by the seal bar 57, and
It is considered that since the heating by 7 is applied, the amount of heating of the horizontal seal portion 54B becomes excessive, and as a result, the resin that has been excessively melted is excessively extruded.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and in the horizontal seal portion, peeling of a seal formed at a portion formed at the start of the seal and occurrence of a polypump at a portion formed at the end of the seal. A heat sealing method and a heat sealing apparatus capable of performing uniform sealing from the start of sealing to the end of sealing without occurrence of a defect or the like due to, and sufficient uniform sealing is performed from the start of sealing to the end of sealing. An object of the present invention is to provide a bag having a high sealing strength.

[0016]

SUMMARY OF THE INVENTION According to the present invention, a pair of seal rolls is provided with at least one pair of seal bars projecting from the side face of each seal roll. In a sealing method of rotating the film sandwiched between these seal bars by the heat applied to the film through the seal bar, the film is sandwiched between the seal bars through the seal bar. The amount of heat applied to the film is gradually reduced so that it becomes maximum at the start of sealing and becomes minimum at the end of sealing.

Further, according to the present invention, a pair of seal rolls, a pair of seal bars protruding from the side surface of each seal roll, and a superimposed heat-fusible film are intermittently formed by the seal bars. Drive means for rotating a pair of seal rolls in opposite directions so as to be sandwiched between the seal bars, and a seal for sealing the film sandwiched between these seal bars by heat applied to the film via the seal bars. The apparatus is characterized in that the amount of heat applied to the film via the seal bar at the time of sealing is gradually reduced so as to be maximum at the start of the seal and minimum at the end of the seal.

In this case, for example, the rotation speed of the pair of seal rolls is gradually increased so as to be minimum at the start of the seal and maximum at the end of the seal, so that the rotation speed is applied to the film via the seal bar at the time of the seal. The amount of heat is gradually reduced.

Alternatively, the amount of heat applied to the film via the seal bar at the time of sealing can be reduced by gradually increasing the distance between the seal bars holding the film so that the distance between the seal bars is minimized at the start of the seal and maximized at the end of the seal. Decrease gradually.

As a specific method of gradually increasing the interval between the seal bars for holding the film, for example, the distance between the rotation centers of the pair of seal rolls is gradually reduced to a minimum at the start of the seal and to a maximum at the end of the seal. For example, a method of enlarging or gradually retracting the surface of each seal bar toward the rotation center of the seal roll along the rotation direction of the seal roll can be used.

Further, the present invention also relates to a bag obtained by sealing a plurality of superposed films having heat-sealing properties, and in particular, a lateral seal portion is formed by the above-mentioned sealing method. Features.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. In the following description, members having the same configuration as the members shown in FIGS. 4 and 5 are denoted by the same reference numerals as those shown in FIGS. 4 and 5, and description thereof is omitted.

An embodiment of the present invention will be described with reference to FIG. In the present embodiment, a filling bag making machine 5 shown in FIGS.
0, the rotational speed of the horizontal seal rolls 55a and 55b is changed as shown in FIG. In FIG. 1, α and γ indicate that the seal bar 57 is 5 in FIG.
The timing at which the positions 7 (α) and 57 (γ) are taken, that is, the start and end of the horizontal seal, respectively, is shown.

As shown in FIG. 1, in the present embodiment, the rotation speed of the horizontal seal rolls 55a and 55b is set so as to be gradually accelerated from the initial speed at the start of the seal and to be the highest at the end of the seal. After the end of the seal, the rotation speed of the horizontal seal rolls 55a, 55b is returned to the initial speed before the start of the horizontal seal by the next pair of seal bars 57.
In the case of the filling bag making machine 50 shown in FIGS. 4 and 5, since one horizontal seal roll 55a, 55b has three seal bars, the horizontal seal rolls 55a, 55a, 55b is configured to repeat the above-described acceleration and deceleration three times per rotation.

Also in this embodiment, as in the prior art, the moving speed of the film 54 and the horizontal seal roll 55
Needless to say, it is necessary to synchronize with the rotation speeds of a and 55b. Therefore, when the present embodiment is implemented, the moving speed of the film 54 and the vertical seal rolls 51a, 51a, 55a, 55b are synchronized with the change in the rotation speed of the horizontal seal rolls 55a, 55b.
The rotation speed of 51b is also changed. In addition, the filling bag making machine 50
However, when other members that should correspond to the moving speed of the film, such as a film feeding roll, a pulling roll, and a cooling roll, are provided, the rotation speed and the like of these members also need to be the same as those of the horizontal seal rolls 55a and 55b. Change in synchronization with the change in rotation speed.

In this embodiment, the horizontal seal roll 55
Although there is no particular limitation on the driving means a and 55b, a servo motor such as a stepping motor can be particularly preferably used. When a stepping motor is used, the rotation speed of the horizontal seal rolls 55a and 55b changes stepwise when viewed microscopically, but is desirably changed so as to be smooth when viewed macroscopically. In the present embodiment, the rotation speed of the horizontal seal rolls 55a and 55b is changed linearly. However, for the purpose of more uniform heating and uniform heat sealing, the change rate of the rotation speed of the horizontal seal rolls 55a and 55b is changed. May be changed as appropriate.

According to the present embodiment, the rotation speed of the horizontal seal rolls 55a and 55b is low at the start of sealing, that is, at the start of sandwiching of the film 54 by the opposing seal bar 57, so that the unheated film 54 can be sufficiently removed. It can be heated to provide the required strength of the seal. Therefore,
According to the present embodiment, in the horizontal seal portion 54B, a portion formed at the start of the seal can be prevented from peeling off the seal.

Further, since the rotation speed of the horizontal seal rolls 55a and 55b becomes higher as the time of the end of the seal is approached, the film 5 is moved from the seal bar 57 with the contact with the seal bar 57.
The amount of heat applied to 4 decreases as it approaches the end of the seal. Therefore, the amount of heating that is further heated through the seal bar 57 in the horizontal seal portion 54B that has already been sufficiently heated by the seal bar 57 can be reduced, and as a result, the amount of heat applied to the seal portion 54B does not become excessive. Poly pool 70
And the occurrence of the edge 71 is minimized.

Therefore, according to the present embodiment, when forming the horizontal seal portion 54B, there is no occurrence of defects such as peeling off of the seal at the start of the seal or occurrence of a poly-pool at the end of the seal. A uniform horizontal seal can be performed until the end.

Another embodiment of the present invention will be described with reference to FIG. In the present embodiment, in the filling bag making machine 50 shown in FIGS. 4 and 5, the horizontal seal rolls (seal rolls) 1a, shown in FIG. 2 are replaced with the horizontal seal rolls 55a, 55b.
1b. FIG. 2 shows a horizontal seal roll 1
(a) is a front view showing a and 1b, (a) at the start of sealing,
(B) shows the state in the middle of the seal, and (c) shows the state at the end of the seal.

The horizontal seal rolls 1a, 1b of the present embodiment
As in the case of the horizontal seal rolls 55a and 55b described above, the pair of roll main bodies 2 extend from the outer peripheral surface of the roll main bodies 2 at equal intervals along the circumferential direction thereof in the axial direction of the roll main bodies 2. And three seal bars 3. The center of rotation P1 of the horizontal seal roll 1a can be displaced in a direction (left-right direction in the drawing) to approach and separate from the horizontal seal roll 1b forming a pair, and the pair of horizontal seal rolls 1b is pressed by a biasing means (not shown). (Left side in the figure).

Reference numeral 9 denotes an end face of the horizontal seal roll 1a.
A cam fixed to be coaxial with the horizontal seal roll 1a,
Reference numeral 10 denotes a cam plate that comes into contact with the outer peripheral surface of the cam 9 from the side of the horizontal seal roll 1b. The cam 9 rotates while contacting the outer periphery with the cam plate 10, and displaces the horizontal seal roll 1 a in a direction to approach and separate from the pair of horizontal seal rolls 1 b according to the distance from the rotation center P 1 to the outer peripheral surface. It is made to let. Specifically, as shown by reference numeral 9a in the drawing, the outer peripheral surface of the cam 9 is directed toward the rotation direction rear side of the horizontal seal roll 1a at a position corresponding to the radially inner side of each seal bar 3. , And gradually project outward in the radial direction. On the other hand, the structure of the horizontal seal roll 1b is the same as that of the horizontal seal roll 55a, and the rotation center P2 is held at a fixed position.

Then, a plurality of superposed films 54 are sandwiched between the opposing seal bars 3 with the rotation of the horizontal seal rolls 1a and 1b, so that the film 54
Are sealed by the heat applied from the seal bar 3,
The opposite films 54 are heat-sealed with each other, and the horizontal sealing portion 54 is formed.
B is formed.

In this case, as shown in FIG. 2A, at the start of sealing, the cam 9 is in contact with the cam plate 10 at a position where the distance d from the rotation center P1 to the outer peripheral surface is minimum. Therefore, the horizontal seal roll 1a is displaced toward the pair of horizontal seal rolls 1b, and the distance between the rotation centers P1 and P2 is minimized. Accordingly, the interval between the seal bars 3 opposed to each other with the film 54 interposed therebetween is also minimized, and the film 54 is sufficiently heated from both sides by the seal bars 3 approaching each other, and is pressed relatively strongly by the seal bars 3. As a result, the necessary sealing strength is given also to the portion formed at the start of the sealing in the horizontal seal portion 54B, and the peeling of the seal at this portion is prevented.

Further, as shown in FIG. 2B, during the sealing, the above-mentioned distance d is slightly longer than at the start of the sealing, so that the horizontal sealing roll 1a is slightly separated from the pair of the horizontal sealing rolls 1b. In the direction of rotation, the center of rotation P
1 and P2 are separated from each other at the start of sealing. Accordingly, the interval between the seal bars 3 opposed to each other with the film 54 interposed therebetween is larger than at the start of sealing, and the amount of heat applied to the film 54 by the seal bars 3 is lower than at the start of sealing.
However, since the film 54 is pre-heated at the start of sealing, even if the amount of applied heat is reduced, the overall amount of heat applied to the film 54 does not become excessive or insufficient. Further, the pressure of the film 54 by the seal bar 3 is slightly reduced, and the film 54 becomes moderate. Therefore, the horizontal seal portion 5
In 4B, a portion formed in the middle of sealing is also given an appropriate sealing strength.

Further, as shown in FIG. 2C, at the end of the seal, the cam 9 is in contact with the cam plate 10 at a position where the distance d from the rotation center P1 to the outer peripheral surface becomes maximum. , The horizontal seal roll 1a is displaced so as to be most distant from the pair of horizontal seal rolls 1b, and the rotation centers P1, P
2 is the maximum. Accordingly, the interval between the seal bars 3 opposed to each other with the film 54 interposed therebetween also becomes maximum, and the amount of heat applied to the film 54 by the seal bar 3 becomes minimum.
However, since the film 54 is already sufficiently heated by the amount of heat applied from the seal bar 3 from the start of sealing to the end of sealing, the film 54 is applied to the film 54 even if the amount of applied heat is reduced. There is no excess or shortage of total heat. In addition, since the pressure of the film 54 by the seal bar 3 is also minimized, the amount of resin that is squeezed and extruded by the seal bar 3 can be minimized. for that reason,
Appropriate sealing strength is also given to a portion of the horizontal seal portion 54B formed at the end of the seal, and in particular, the occurrence of unnecessary poly pools and edges due to excessive extrusion of the excessively molten resin is prevented. Is done.

Therefore, also in the present embodiment, when forming the horizontal seal portion 54B, there is no occurrence of defects such as seal peeling at the start of the seal or occurrence of a polypump at the end of the seal. A uniform horizontal seal can be performed.

In this embodiment, the cam is used as a means for displacing the rotation center P1 of the horizontal seal roll 1a. However, a dedicated drive means independent of the drive means for rotating the horizontal seal roll 1a is used. Alternatively, the rotation center P1 of the horizontal seal roll 1a may be displaced. Further, the rotation center P2 of the horizontal seal roll 1b may be displaceable similarly to the horizontal seal roll 1a.

Still another embodiment of the present invention will be described with reference to FIG. In the present embodiment, a horizontal seal roll (seal roll) 1 shown in FIG. 3 is used in the filling and bag making machine 50 shown in FIGS.
c, 1d. FIG. 3 is a front view showing the horizontal seal rolls 1c and 1d. FIG.
(B) shows the state in the middle of the seal, and (c) shows the state at the end of the seal.

The horizontal seal rolls 1c, 1d of the present embodiment
As with the horizontal seal rolls 55a and 55b described above, a pair of roll bodies 2a and an outer peripheral surface of the roll body 2a
Roll body 2a projecting at equal intervals along its circumferential direction
And three seal bars 3a extending in the axial direction. In addition, the surface 31 of each seal bar 3a
Is an inclined surface that gradually retreats to the rotation center Q side of the horizontal seal rolls along the rotation direction of the horizontal seal rolls 1c and 1d.

Then, a plurality of superposed films 54 are sandwiched between the opposing seal bars 3a with the rotation of the horizontal seal rolls 1c and 1d, so that the film 5
4 are sealed by the heat applied from the seal bar 3a, and the opposing films 54 are heat-sealed to form a horizontal seal portion 54B.

In this case, as shown in FIG. 3A, at the start of the seal, the distance from the surface 31 of each seal bar 3a to the center of rotation Q becomes maximum. The interval between the bars 3a is minimized. Therefore, the film 54 is provided with the seal bars 3a approaching each other.
Is sufficiently heated from both sides, and a relatively strong pressure is applied by the seal bar 3a. As a result, of the horizontal seal portion 54B, the portion formed at the start of the seal also
The necessary seal strength is provided, and peeling of the seal at this portion is prevented.

The surface 31 of the seal bar 3a is an inclined surface which gradually retreats to the rotation center Q side of the horizontal seal rolls 1c and 1d along the rotation direction of the horizontal seal rolls 1c and 1d. As shown in ()), during the sealing, the interval between the surfaces 31 opposed to each other across the film 54 becomes larger than at the start of sealing, and the amount of heat applied to the film 54 by the seal bar 3a is lower than at the start of sealing. .
However, since the film 54 is pre-heated at the start of sealing, even if the amount of applied heat is reduced, the overall amount of heat applied to the film 54 does not become excessive or insufficient. In addition, the pressure of the film 54 by the seal bar 3a is slightly reduced, and the film 54 becomes moderate. Therefore, a suitable seal strength is given also to a portion formed in the middle of the seal in the horizontal seal portion 54B.

Further, as shown in FIG. 3C, at the end of the sealing, the interval between the surfaces 31 opposed to each other with the film 54 therebetween is maximized, and the amount of heat applied to the film 54 by the seal bar 3a is minimized. . However, since the film 54 is already sufficiently heated by the amount of heat applied from the seal bar 3a during the period from the start of sealing to the end of sealing, the film 54 is applied to the film 54 even if the amount of applied heat is reduced. There is no excess or shortage of total heat. In addition, since the pressure applied to the film 54 by the seal bar 3a is also minimized, the amount of resin that is squeezed and extruded by the seal bar 3a can be minimized. Therefore, the horizontal seal portion 54B
Among them, appropriate sealing strength is given also to a portion formed at the end of sealing, and in particular, formation of unnecessary poly pools and edges due to excessively extruded resin that has been excessively melted is prevented.

Accordingly, also in the present embodiment, when forming the horizontal seal portion 54B, there is no occurrence of defects such as peeling of the seal at the start of the seal and occurrence of defects due to the formation of the polypump at the end of the seal. A uniform horizontal seal can be performed.

In the present embodiment, the center of rotation of the horizontal seal rolls 1c and 1d is fixed at a fixed position. However, as shown in FIG.
The distance between them may be adjustable. That is, the interval between the seal bars 3a may be adjusted based on both the shape of the seal bars 3a and the adjustment of the position of the rotation center. The horizontal seal roll 1d has the same structure as the horizontal seal rolls 55a and 55b in FIGS.
The spacing between the seal bars 3a may be adjusted only by using the seal bar 3a.

Further, the rotation speed of the horizontal seal rolls 1a to 1d in the embodiment shown in FIGS. 2 and 3 is changed as shown in FIG. May be controlled.

The horizontal seal rolls 1a to 1d of the above-described embodiments are not limited to the horizontal seal rolls of a bag making machine for a bag body provided with two vertical seals as shown in FIG.
It can also be applied to horizontal seal rolls for other forms of bags, such as pillow bags and gusset bags with one vertical seal.
As for 4, a film obtained by folding a single film or a film obtained by overlapping a plurality of films can be used.
The roll bodies 2, 2a and the seal bars 3, 3a, 57
The specific manufacturing method is not particularly limited, and may be integrally formed or separately manufactured and fixed by welding or the like. The number of the seal bars 3, 3a, 57 is not particularly limited, and at least one seal bar 3, 3a, 57 may be provided for each of the horizontal seal rolls 1a to 1d. Also,
In each of the above embodiments, the horizontal seal roll 1a
Heat seals in which the film 54 is heated by heaters incorporated in the seal bars 3, 3a, 57 of ~ 1d, 55a, 55b to form a horizontal seal portion 54B are employed.
There is no limitation on the heating method of the film 54, and an ultrasonic seal or the like for applying the ultrasonic vibration to the film 54 through the seal bars 3, 3a, 57 to heat the film 54 and form the horizontal seal portion 54B is also appropriate. Can be adopted.

[0049]

As described in detail above, according to the heat sealing method and the heat sealing apparatus of the present invention, the rotation of the seal roll is considered in consideration of the heating state of the seal from the start to the end of the heat seal. Since the speed and the interval between the seal bars are adjusted to control the overall amount of heat applied to the seal bar, the amount of heat applied to the film becomes uniform throughout the seal portion. As a result, according to the heat sealing method and the heat sealing device of the present invention, there is no occurrence of a defect due to the occurrence of a polypump at the end of the seal or the end of the seal at the start of the seal. It is possible to obtain a bag having a uniform sealing portion having a sufficient sealing strength.

[Brief description of the drawings]

FIG. 1 is a graph showing a change in rotation speed of a seal roll according to an embodiment of the present invention.

FIGS. 2A and 2B are front views showing a seal roll according to another embodiment of the present invention, in which FIG. 2A shows a state at the start of sealing, FIG. 2B shows a state in the middle of sealing, and FIG. Things.

FIGS. 3A and 3B are front views showing a seal roll according to another embodiment of the present invention, in which FIG. 3A shows a state at the start of sealing, FIG. 3B shows a state in the middle of sealing, and FIG. Things.

FIG. 4 is a perspective view showing an example of a structure of a filling and bag making machine to which the present invention can be applied.

FIG. 5 is a view for explaining a change in a positional relationship of a seal bar associated with formation of a horizontal seal portion in the filling and making machine shown in FIG.

FIG. 6 is a partial cross-sectional view of a film showing a state of occurrence of a poly pool near a horizontal seal portion.

[Explanation of symbols]

1a, 1b, 1c, 1d, 55a, 55b Horizontal seal roll (seal roll) 2, 2a, 56 Roll body 3, 3a, 57 Seal bar 9 Cam 10 Cam plate 54 Film 61 Bag body P1, P2, Q Seal roll Rotation center

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3E050 AB02 AB05 DD04 DF02 FB01 FB07 3E075 AA09 BA42 BA52 CA02 DD13 DD32 DD44 DD46 DE25 GA04 3E094 AA12 BA01 BA07 CA08 CA10 CA22 DA08 EA03 GA01 GA03 GA11 HA08

Claims (9)

[Claims] Claims: 1. A pair of two or more seal rolls, each of which includes a pair of seal bars projecting from a side surface of each seal roll,
Rotated in opposite directions to intermittently sandwich the superposed films having heat-fusibility, the film sandwiched between the seal bars is applied to the film via the seal bars. In the sealing method for sealing by heat, the amount of heat applied to the film via the seal bar at the time of the sealing is gradually reduced so as to be maximum at the start of sealing and minimum at the end of sealing. Method. 2. The rotational speed of the pair of seal rolls is:
2. The sealing method according to claim 1, wherein the value is gradually increased so as to be minimum at the start of the seal and maximum at the end of the seal. 3. The sealing method according to claim 1, wherein an interval between the seal bars for sandwiching the film is gradually enlarged so as to become minimum at the start of the seal and to become maximum at the end of the seal. 4. A pair of two seal rolls, a pair of seal bars projecting from a side surface of each seal roll, and
Driving means for rotating the pair of seal rolls in opposite directions so that the superimposed film having heat-fusibility is intermittently held by the seal bar, and is sandwiched between the seal bars. In the sealing device for sealing the film by the heat applied to the film through the seal bar, the amount of heat applied to the film through the seal bar at the time of the sealing, the maximum at the start of sealing, the seal A sealing device characterized by a gradual decrease to a minimum at the end. 5. A rotating speed of the pair of seal rolls,
5. The sealing device according to claim 4, wherein the value is gradually increased so as to be minimum at the start of the seal and maximum at the end of the seal. 6. The sealing device according to claim 4, wherein the interval between the seal bars for sandwiching the film is gradually increased so as to be minimum at the start of the seal and maximum at the end of the seal. 7. The sealing device according to claim 6, wherein the distance between the rotation centers of the pair of seal rolls is gradually increased so as to be minimum at the start of the seal and maximum at the end of the seal. 8. The sealing device according to claim 6, wherein the surface of the seal bar is gradually retracted toward the rotation center of the seal roll along the rotation direction of the seal roll. 9. A bag obtained by sealing a plurality of heat-fusible films stacked one on another, wherein the lateral sealing portion is formed by the sealing method according to any one of claims 1 to 3. A bag body, wherein a bag is formed.