JPS5914326Y2 - Thermal bonding equipment in packaging machines - Google Patents

Description

[Detailed description of the invention] This invention forms a packaging film into a tube, places the item to be packaged inside it, and heat-bonds and cuts the packaging film before and after the placed item to complete it as a single packaging bag. This is an improvement to the thermal bonding device of the packaging machine.

To explain it with a diagram, FIG. 1 shows an outline of the above-mentioned packaging machine, in which a strip-shaped packaging film 1 is formed into a cylinder by a former 4, and an article 3 to be packaged is conveyed by a supply conveyor 2 and formed into a cylinder. The packaging machine enters the wrapped packaging film 1', heat-bonds and cuts the packaging films on the front and back of the article 3, completes the packaging bag 6, and transports it on a delivery conveyor 7.
As shown in Fig. 3, the thermal bonding cutting mechanism consists of a pair of upper and lower rotary blades that are heated by an electric heater.
A rotary hot plate 5a equipped with 0 and a rotary hot plate 5b equipped with a receiving blade 11 in contact with the cutting edge of the fixed blade 10 rotate according to the packaging timing to thermally bond and cut the cylindrical packaging film, as shown in FIG. The packaging bag 6 shown in FIG. 9
However, since the upper and lower chevrons 12 sandwich and bite the packaging film through heat-pressure welding, cracks may occur at the seal line 9, making the part more likely to break. When nitrogen gas or the like is filled and sealed together with 3, the gas may leak from the cracked seal line 9.

Furthermore, there is a drawback that external pressure applied to the packaging bag 6 (such as when stacking in boxes) causes the bag to break at the seal line 9.

Research into the cause of this problem reveals that the rotary type thermal bonding device that has been commonly used in the past has a thermal bonding surface as shown in FIG.

That is, the heat-bonded surface of the chevron 12 forming the uneven surface draws an arc 14 with a radius D' from the rotation center point P', and the chevron 12 is formed on the line of the arc 14. also forms a chevron 12 with a similar arc.

(See FIG. 4) In the conventional structure, a fixed blade 10 or a receiving blade 11 is provided between the chevrons 12.

When the chevron 12 is formed by the arc 14 centered on point P', the upper and lower corners 13 become sharp like cutting blades when sandwiching the packaging film and engage with the cylindrical packaging film, so the seal line 9 It is easy to crack and break from there, and the chevron-shaped shape 12 with slightly rounded tips and valleys can cause cuts in the sealing surface of the bag, depending on the material of the packaging film. It was found that the shape was not necessarily suitable for thermal bonding.

This invention has the purpose of preventing the occurrence of cracks, breaks, etc. in the seal line 9 of the heat bonding part 8, and improving the heat bonding and sealing properties.The improved structure is shown in Figs. 5 and 6. explain.

To form the thermal bonding surfaces of the pair of rotary hot platens 5a and 5b, instead of using a circular arc from the center of rotation as in the past, a circular arc with a radius D// is made from a point P// which is slightly eccentric toward the outer circumference of rotation. 15, and an uneven thermal bonding surface is formed on the circular arc 15, and a similar circular arc is formed on the thermal bonding surface on the side of the upper heating plate 5a.

When this eccentric arc 15 is used, a slight gap is created between the two lower corners of the corner portion 18, so that the seal line 9 of the thermally bonded portion 8 does not suffer from cracks or breaks.

In addition, the uneven heat-adhesive surface gradually becomes stronger, so
Appropriate pressure was applied, resulting in improved thermal adhesion of the packaging film.

Further, in the figure, in order to prevent the packaging film from cracking or breaking, the unevenness on the heat bonding surface is not formed like a chevron pattern 12, but instead is formed into a pattern similar to an involute tooth pattern 16 using an involute curve.

With this shape, the packaging film has an involute tooth shape 16 with a curved and rounded shape, so it can be thermally bonded without breaking even when it is strongly heat-pressed, and as a result of experiments, it has been found that the packaging film has better sealing properties than the conventional chevron-shaped structure 12. It has also become even better.

In addition, the thermal bonding surface can be prepared by using a tooth profile 17 that has a slightly different shape than the illustrated involute tooth profile 16 and has a rounded shape, for example, the height and valley of the tooth profile are lowered as shown in FIG. This structure improves the adhesion of the packaging film, making it possible to prevent damage such as cuts and gas leakage.

By configuring the thermal adhesive surface of the structure of the present invention as described above, the problems of adhesion, tearing, and gas leakage of packaging bags, which have been difficult until now, have been solved, and the effect is great.

[Brief explanation of the drawing]

Figure 1 is a front view showing an overview of the packaging machine, Figure 2 is a perspective view of a packaging bag made with the packaging machine in Figure 1, Figure 3 is a front view of a conventional thermal adhesive cutting device, and Figure 4. 3 is an enlarged view of the chevron-shaped portion of the thermal bonding surface of FIG. 3, FIG. 5 is a front view of the thermal bonding cutting device of this invention, and FIG. 6 is an enlarged view of the tooth-shaped portion of the thermal bonding surface of FIG. 5a, 5b: Rotating hot plate, 15: Arc, 16: Involute tooth shape, 17: Deformed involute tooth shape, P″: Eccentric point, D″: Radius.

Claims (1)

[Scope of utility model registration request] 1. A thermal bonding device for a packaging machine, in which a thermal bonding surface of a pair of rotary hot platens is formed by forming a thermal bonding surface with unevenness in an arc having a radius from a position eccentric from the center of rotation of the rotary hot platens. 2. The thermal bonding device according to claim 1, wherein the thermal bonding surface has a shape similar to an involute tooth shape.