JPH06155578A - Heat sealer - Google Patents

Abstract

PURPOSE:To equalize sufficiently also heat-sealing strength of respective lateral sealing parts leaving a space between them by making the lateral sealing part of a bag have almost uniform heat-sealing strength over its whole length. CONSTITUTION:Fixing side and movable side roll body parts 1, 5 wherein two rolls make a pair and are driven by rotation in a revers direction with each other, and heat-sealing edges 10, 11 which are provided to such respective roll body parts 1, 5, extended in their length directions or peripheral directions, and have a peripheral arc state surface, are provided in a heat sealer. A forcing means 14 which energizes the movable side roll body part 5 toward the fixing side roll body part 1 always by specific force, and besides an elastic means 15 which pushes the movable side roll body part 5 back in a direction separating from the fixing side roll body part 1 are arranged. The pushing back force of the elastic means 15 is reduced within a range of 2-8kgf per 10mum according to increase in a nip from a balance posture between the pushing back force and the energizing force of the forcing means 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sealing device for heat-sealing a film material or a sheet material having a hot-melt resin layer with each other, and more particularly to a pressing structure for a heat-sealing roll. is there. In particular, the present invention enables a uniform heat seal over the entire length of the lateral seal portion of the bag at the same time, and at the same time, sufficiently equalizes the heat seal strengths of the lateral seal portions located at intervals from each other. The present invention relates to a heat sealing device for bag making machines.

[0002]

2. Description of the Related Art As a known heat-sealing device applied to an automatic filling and bag-making machine, there is, for example, the one previously disclosed by the applicant in JP-A-1-188328.

This prior art will be described with reference to the example of a horizontal seal roll with reference to FIG. 3. A pair of rolls 32 and 33 are provided which are arranged in close proximity to each other and are parallel to each other, and are driven to rotate in opposite directions. Each roll 32, 33
In the place where the heat-sealing blades 34, 35 extending in the lengthwise direction thereof and having the arcuate surface in the circumferential direction are provided, each of the rolls 32, 33, at two locations spaced apart in the axial direction, Position control flanges 36, 37 that contact each other on the peripheral surface
And the arcuate surfaces of the heat seal blades 34, 35 are located somewhat inward in the radial direction from the peripheral surfaces of the position regulating flanges 36, 37.

In such a heat-sealing device, the close positions of the pair of rolls 32 and 33 are specified by the abutment of the respective position regulating flanges 36 and 37.
Proper heat sealing can be realized by always reliably ensuring the required gap for heat sealing of the film material, sheet material, etc. between the heat sealing blades of the respective rolls that cooperate with each other.

[0005]

By the way, in such a heat seal roll, for example, a roll 33 as a fixed roll and a roll 32 as a movable roll are used.
As shown in the figure, press (F + F =) 2F,
A lateral seal portion H is formed on a film material W folded in two in the width direction and extends over the entire width of the film material W at intervals in the length direction.
When forming S, each heat seal blade 34, 35
Since the film material W is sandwiched by the intermittently, the movable-side roll 32 receives an impact in a direction opposite to the pressing force 2F and separates from the fixed-side roll 33 each time the sandwiching is performed. A small backward displacement will be performed.

At this time, if the backward displacement amounts of the position regulating flange 36 shown on the left side of the roll and the position regulating flange 36 shown on the right side of the roll 32 are both the same in correspondence with the sandwiching thickness, it is acceptable. For example, if the roll 32 is displaced backward in parallel over the entire length by an amount corresponding to the sandwiching thickness, it can be said that the horizontal seal portion HS is sufficiently uniformly heat-sealed over the entire length.

However, in reality, in relation to the required bag width, the heat-sealing blades 34, 35 rarely contribute to the heat-sealing over their entire length, and the heat-sealing blades 34, 35 mostly As illustrated by the phantom line in the figure, the film material W is laterally sealed only at the positions deviated to the left end portions of the rolls 32 and 33. Moreover,
Since the center of mass of the movable roll 32 including the rotary drive system and the like is not necessarily located at the center in the length direction of the roll, the heat-sealing blades 34, 35 are made to be the film material W.
When the rolls 32 are sandwiched, the retracting force acting on the roll 32 (hereinafter referred to as "reaction force") is different from each other at the left and right end portions of the roll 32. At a line speed at which the traveling speed of the material W exceeds 5 m / min, the left and right roll end portions vibrate differently from each other due to the repeated action of the reaction force on the roll 32. hand,
A large difference occurs between the backward displacement of the left end of the roll and the backward displacement of the right end, and in addition, due to the vibration that is considered to be self-excited vibration, the respective displacements of the left and right ends are It may change greatly depending on the circumferential position. Therefore, the sealing condition of the lateral seal portion HS, and by extension,
It was extremely difficult to make the seal strength sufficiently uniform over its entire length, and also to make the seal strength of each of the lateral seal portions HS spaced apart uniform.

FIG. 4 is a graph showing this, and FIG.
Heat seal blades 3 for the horizontal seal rolls shown in
Heat seal for each of 4 and 35 4 pieces
The diameter of the arc passing through the surfaces of the blades 34 and 35 is both 90 mmφ,
Heat seal blade with a length of 150 mm
In the heat seal device with the interval of 34 and 35 set to 50μ,
An EV with a thickness of 30μ on a polyester film with a thickness of 16μ
The width formed by stacking A mm film material W, its width
Fold it in half from the center of the
Roll on the movable side when the horizontal seal part HS is formed
Each not shown supporting the respective shaft end portions of 32
The amount of backward displacement of the bearing block of the film material W
The traveling speed of 6m / min, 12m / min and 24m / min
Sometimes, as shown in Figs. 4 (a), (b) and (c),
became. In this case, drive the left end of the movable roll 32.
It is connected to the dynamic system and the pressing force 2F of the roll 32 is 100 kgf.
did.

The upper graph in FIG. 4 shows the displacement on the left end side, that is, on the sandwiching side of the film material W, and the lower graph shows the displacement on the right end side, with the horizontal axis as the time axis. The base line is the rolls 32,
33, the peripheral surface contact positions of the respective position regulating flanges 36 and 37 are shown, and the positive direction of the vertical axis shows the amount of backward displacement. In the figure, the parts numbered No. 1 to No. 4 indicate the retracted displacement positions when the corresponding numbers assigned to the respective heat-sealing blades 34, 35 cooperating with each other are in operation.

According to these graphs, the film material W
Irrespective of the traveling speed of the heat-sealing blades 34, 35, the backward displacement amount of the roll end portion when the heat-sealing blades 34 and 35 are operated tends to be closer to the right end portion side than the left end portion side which is the sandwiching side of the film material W. It is clear that the pressing force of the heat-sealing blade against the film material W decreases at the right end portion of the roll 32, that is, the heat-sealing strength may be insufficient at the right end portion. I know that there is.

Further, here, the heat-sealing blades 34 of No. 1 to No.
The amount of receding displacement during the action of 35 becomes different, and therefore, the sealing strength of the lateral seal portions HS spaced apart from each other is also likely to be non-uniform.

That is, according to the graph, the amount of retreat displacement when the No. 1 and No. 3 heat-sealing blades are in operation is large at both left and right end portions, and the values are almost the same. On the other hand, the displacements of No. 2 and No. 4 during operation are smaller than those displacements, and especially on the right end side, the mutual displacement of No. 2 and No. 4 is There is a big difference, so in the No. 1 and No. 3 parts, the amount of backward displacement is too large,
It is considered that the roll pressing force against the film material W is insufficient, and conversely, in the No. 2 portion on the right end side, the pressing force against the film material W becomes too large and the film material W is melted by heat. It is possible that most of the resin has been pushed away. The backward displacement of No. 2 on the left end side is close to that of No. 4, but there is no peak of backward displacement,
Since 32 can be said to be in the middle of forward displacement, it is difficult to judge whether the pressing force of the film material W at this portion is excessive or insufficient.

Table 1 shows specific amounts of displacement of the left end portion and the right end portion from the reference line at the respective speeds.

[0014]

[Table 1]

According to this, it is recognized that the retreat displacement amount of the right end portion is approximately 2-3 times the displacement amount of the left end portion at each speed except for the No. 2 portion.

The present invention has been made as a result of studies for solving the above-mentioned problems of the prior art, and an object of the present invention is to provide each of the left and right end portions of the movable side roll main body. By making the amount of receding displacement of each heat seal blade substantially equal and also making the amount of each receding displacement when each heat seal blade acts also substantially uniform, the sealing strength of one horizontal seal part can be made sufficiently uniform over its entire length. Another object of the present invention is to provide a heat-sealing device capable of making the respective lateral sealing portions positioned at intervals have a sufficiently uniform sealing state.

[0017]

SUMMARY OF THE INVENTION The present invention is particularly directed to the formation of a lateral seal portion between the heat seal blades provided on the movable side and fixed side roll body portions and cooperating with each other. In addition, for example, against the backward displacement of the movable side roll main body portion caused by the impact force acting on those heat-sealing blades by sandwiching the film material, the movable side roll main body portion is pushed back far beyond the impact force. A force is applied in advance, and the pushing-back force is reduced at a specific rate according to the increase in the heat-seal blade gap and, by extension, the amount of retreat displacement of the roll body part, so that the impact side of the movable roll body part By fully mitigating the effect on the movable side roll body part, the movable side roll body part is substantially parallel, in other words, the left and right end parts thereof are evenly rearward. Can be displaced, moreover,
It is possible to effectively remove the vibration component that is considered to be caused by self-excited vibration and the like, and to make the respective peak values of the backward displacement amount at the time of the action of the heat sealing blades that cooperate with each other substantially equal. It was made based on the knowledge of.

That is, the heat-sealing device of the present invention is provided with a fixed-side and a movable-side roll main body part which are paired with two rolls and are driven to rotate in mutually opposite directions. , Extending in their lengthwise or circumferential direction, provided with heat-sealing blades having an arcuate surface in the circumferential direction, and preferably, at positions axially spaced from each roll body portion,
Where the position regulating flanges that contact each other on the peripheral surface are provided, the movable roll body is constantly urged toward the fixed roll body with a constant force, for example, a constant force of about 200 to 500 kgf. While providing the pressing means, an elastic means for displacing the movable side roll main body portion in a direction away from the fixed side roll main body portion is arranged, and the pushing back force of the elastic means is balanced with the urging force of the elastic means. 2 to 10μ for increasing roll gap from the state
It is to be reduced within the range of 8 kgf.

[0019]

In this heat seal device, for example, the movable roll main body is kept at a constant 300 k by the pressing means.
The force of gf pushes the fixed-side roll main body toward the fixed-side roll main body, and this also applies, for example, the pushing back force of the elastic means under the mutual contact state of the position regulating flanges provided on the respective roll main body. When balanced with the pressure, the movable roll body portion is supported with substantially no external force.

Here, by sandwiching the film material between the heat-sealing blades of both roll main body parts, the movable side roll main body part is displaced backward by, for example, 100 μm, and it is assumed that the pushing back force of the elastic means is reduced by 50 kgf. At this time, the static balance formula acting on the movable side roll main body is the pressing force (300 kgf) = pushing back force (250 kgf) + the force due to the film material being sandwiched (50 kgf). Power, ie
The impact reaction force acting on the heat seal blade is sufficiently absorbed by the reduction of the push-back force, and the push-back force has a magnitude as large as five times the impact reaction force.

For this reason, it can be said that the receding displacement of the respective end portions of the roll main body portion here is performed under the control of a large push-back reaction force, rather than by an impact reaction force, and therefore the heat-sealing blade. However, even if the film material is sandwiched by only one of the end portions, the respective end portions of the roll main body portion are evenly affected by the position where the impact reaction force generated thereby is hardly affected. Therefore, the lateral seal portion is heat-sealed with substantially uniform strength over its entire length.

Moreover, here, as shown by the above-mentioned balance equation, the generated impact reaction force can be sufficiently absorbed with a large pushing back force, and the movable roll main body portion is not subjected to other than the impact reaction force. Since it is a rigid mass system that is rigid enough to ignore the effect of a small external force,
The non-sided vibration component caused by self-excited vibration and the like can be almost completely removed, and therefore, when the respective heat-sealing blades cooperate with each other, the respective backward displacement amounts of the movable-side roll main body portion are excessive or insufficient. As a uniform amount, the heat sealing strength of each of the lateral sealing portions at intervals can also be made substantially uniform.

Since this heat seal device operates as described above, the impact reaction force can be adjusted to some magnitude, that is, the film material or sheet without adjusting the pressing force of the movable roll body. Appropriate heat sealing can always be performed regardless of the thickness of the material.

By the way, in this apparatus, the pushing back force of the elastic means is reduced within the range of 2 to 8 kgf per 10 μm, and when it is less than 2 kgf, especially in the lateral seal portion, the heat seal blade and the film material or sheet are used. It is empirically recognized that the damage of the film or sheet material at the position of contact with the material becomes large, but when it exceeds 8 kgf, heat seal failure occurs due to insufficient pressing force of the heat seal blade. Is.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of the present invention,
1 (a) is a schematic plan view of the apparatus, and FIG. 1 (b) is a schematic side view thereof.

Here, each axial line portion of the fixed-side roll main body portion 1 is bearing-supported by the bearing block 2, and each of the bearing block 2 is fixed to the housing 3 of the automatic filling bag making machine. One end of the fixed-side roll body portion 1 is provided with a bevel gear 4
Is connected to a rotation drive means (not shown).

Further, here, the movable side roll main body portion 5 is arranged in parallel with the fixed side roll main body portion 1, and the bearing blocks 6 provided at the respective shaft end portions of the movable side roll main body portion 5 are A frame member 7 projecting from 2 slidably supports the fixed-side roll body portion 1 in the respective directions of approaching and separating from each other, and is provided at one end of the movable-side roll body portion 5. The driven gear 8 meshes with the drive gear 9 provided on the fixed-side roll body portion 1.

According to such a structure, the roll main body portions 1 and 5 can be rotated in mutually opposite directions based on the action of the rotation driving means (not shown), and
The movable roll body portion 5 can be translated for a slight distance in a direction approaching the fixed roll body portion 1 and in a direction opposite thereto by the action of an external force applied thereto.

Further, each of the roll body portions 1 and 5 also has a circumferential arcuate surface extending in the longitudinal direction at intervals in the circumferential direction, as described in the prior art. The four heat seal blades 10 and 11 are provided, and the position regulating flanges 1 are axially spaced from each other and are in contact with each other on their circumferential surfaces.
2 and 13 are provided, in which at least one arcuate surface of the heat seal blades 10 and 11 is positioned somewhat inward in the radial direction from the peripheral surface of the position regulating flanges 12 and 13. According to such a configuration, the heat seals that cooperate with each other by rotating the roll main body portions 1 and 5 with the position control flanges 12 and 13 being in contact with their peripheral surfaces. Between the blades, for example, a constant gap for sandwiching the film material is always secured. By the way, from the roll body parts 1, 5 to the position regulating flanges 12, 13
It is also possible to omit, and in this case, a predetermined heat seal blade gap can be secured by specifying the mutual distance between the bearing blocks 2 and 6.

In addition, in this example, the pressing means 14 for constantly urging the respective bearings 6 of the movable side roll main body portion 5 toward the fixed side roll main body portion 1 with a constant force are provided in the respective bearing blocks 6 thereof. And the frame member 7, the elastic means 15 for pushing back the bearing blocks 6 in a direction away from the fixed-side roll body portion 1,
It is interposed between the respective bearing blocks of the respective roll body portions 1 and 5.

Here, the pushing-back force of each elastic means 15 is an appropriate balance posture between the force and the urging force of each pressing means 14,
For example, it is selected so that the peripheral surfaces of the respective position regulating flanges 12 and 13 just come into contact with each other and the contact surface pressure is reduced in the range of 1 to 4 kgf per 10 μm with respect to the increase of the roll gap from the state of zero. Note that this reduction rate is calculated by using two elastic means.
As for 15, the range is 2 to 8 kgf per 10 μm.

More specifically, for example, by using two pressing means 14 which can be a combination of a spring and an air cylinder, the movable side roll main body portion 5 is fixed with a total force of 300 kgf. When pushing to the side, the pushing back force of the two elastic means 15 is 300 kgf at the contact position of the position regulating flanges 12 and 13, and is in the range of 292 to 298 kgf when the flanges 12 and 13 are separated by 10 μm. When the distance is 100 μm, the range is 220 to 280 kgf.

According to the heat-sealing device constructed as described above, in particular, due to the action of the large pushing-back force of the elastic means 15, as described above, the film material or the like is sandwiched between the heat-sealing blades. Thus, the influence of the impact reaction force acting on the movable-side roll main body portion can be removed very effectively, and the heat-sealed state of the lateral seal portion can be made sufficiently uniform over its entire length. In addition, the rigidity of the spring-mass system of the movable-side roll main body can be increased, unnecessary vibration components can be removed, and the heat-sealed state of each horizontal seal portion with a spacing can also be made sufficiently uniform. .

In addition, according to this apparatus, as the thickness of the film material or the like sandwiched between the heat-sealing blades becomes larger, the sandwiching force acting on the film material itself becomes larger. With respect to a slight change in thickness, proper heat sealing can always be performed without adjusting the pressing force of the movable-side roll main body. Therefore, the present invention is extremely useful when applied to not only the horizontal sealing device but also the vertical sealing device.

FIG. 2 shows the amount of backward displacement of the movable-side roll body portion 5 of the apparatus shown in FIG. 1 when the traveling speed of the film material is 6 m / min, 12 m / min and 24 m / min. It is a graph similar to FIG. Note that FIG.
Whereas the temperature of the heat seal blade is 23 ℃, the heating temperature of the heat seal blade is 178 ℃.
The difference is that. Here, when the amount of backward displacement of each of the left end portion and the right end portion, which are the sandwiching side of the film material, was measured, it was as shown in Table 2.

[0036]

[Table 2]

According to Table 2, the difference in the amount of backward displacement between the left and right side end portions is much smaller than that in the prior art, and the backward displacement in each of No. 1 to No. 4 is large. It is clear that the variation in quantity is effectively reduced, especially in the right end part, and it can be seen that these become more noticeable as the speed increases. It should be noted that the maximum variation in the amount of displacement of each of No. 1 to No. 4 in the left end portion is larger than that in the conventional technique because the position regulating flanges provided in the roll main body portions 1 and 5 are larger. 1
It is thought that this is due to the processing accuracy of 2 and 13.

[0038]

As described above, according to the present invention, the heat seal state of the lateral seal portion can be made sufficiently uniform over the entire length thereof mainly based on the action of the elastic means, and The heat-sealed states of the respective laterally-sealed portions, which are spaced apart from each other, can be made substantially uniform. And further, against changes in the thickness of the film member and other heat seal members,
The clamping force acting on it can be adjusted automatically.

[Brief description of drawings]

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

FIG. 2 is a graph showing a retracted position of a movable-side roll main body portion.

FIG. 3 is a diagram showing a conventional technique.

FIG. 4 is a graph showing a backward displacement amount of a movable roll according to a conventional technique.

[Explanation of symbols]

 1 Fixed-side roll main body 2, 6 Bearing block 3 Housing 5 Movable-side roll main body 7 Frame member 10, 11 Heat seal blade 12, 13 Position regulation flange 14 Pressing means 15 Elastic means

Claims (1)

[Claims] 1. A fixed-side and movable-side roll main body part that is paired with two rolls and is driven to rotate in mutually opposite directions, and these roll main body parts are provided in the respective roll main body parts, and their length direction or circumferential direction. And a heat-sealing blade having an arcuate surface in the circumferential direction, and a pressing means for constantly urging the movable-side roll main body toward the fixed-side roll main body with a constant force. , An elastic means for pushing back the movable roll main body portion in a direction away from the fixed side roll main body portion, and the push-back force of this elastic means from the balance posture between it and the biasing force of the pressing means. 10 μm for increasing roll gap
The heat seal device is characterized by a reduction in the range of 2 to 8 kgf.