JPH054995Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is generally used to produce packaging films or Involved in improving impulse sealing devices for sheets.

(Prior Art) In general, impulse sealing devices reduce the heat capacity of the heating element when thermally bonding the above-mentioned synthetic resin films or sheets. The synthetic resin film or sheet is kept under pressure for a while after the current is turned on and the current is cut off.
A method is used to wait for the joint to cool before separating. That is, it is thermal shock bonding. Conventionally, films or sheets of synthetic resin to be thermally bonded are stacked on a heat-resistant rubber cushion table made of silicon-based synthetic rubber with good flatness, and heated under pressure. On the heating side, methods such as attaching a radiator to the seal bar, providing water cooling or air cooling, or blowing air from outside are usually used to speed up cooling. In order to prevent short circuits caused by the seal bar, the nichrome wire heating element is connected to the composite wire by the seal bar, with a heat-resistant and durable tape or film insulating material such as glass fiber cloth or fluorine-based synthetic resin interposed therebetween. Press-bonded to resin film or sheet bonded material. In this way, the heating element is crimped to the joint, and when the overlapping joints melt and their structures intermingle and become integrated, the current is cut off and the cooling is continued. As one process progresses, the joint is pulled apart approximately on the center line and cutting is performed, and the pressure bonding by the seal bar is released, completing one cycle of the processing process.

(Problem to be solved by the invention) However, in the conventional cooling method, the seal
Since the bar is cooled directly or indirectly and/or the joint is entirely cooled by air blowing, the joint that is ultimately to be cooled is only indirectly cooled. Unfortunately, cooling was insufficient. In other words, if we consider the processing object mainly consisting of synthetic resin films or sheets to be joined, once the joined parts are cooled to below the plastic temperature, the joined material will be damaged by tension during the cutting process. It is necessary to maintain seal strength by preventing the film or sheet from decreasing in thickness. However, with indirect cooling, if you try to maintain a high seal strength at the joint, the strength of the cut section will also be high, making the cutting process difficult and making it impossible to cut cleanly. If a method of lengthening the time is adopted, one cycle of processes becomes longer and production efficiency decreases. On the other hand, if you try to cut cleanly or quickly, the seal strength will decrease. In addition, if the joint is a thick workpiece such as FPE (foamed polyethylene sheet) or a cell sheet, the repulsion force between the sheets is
In other words, the elasticity of the sheet itself causes the joint to be stretched, reducing the sealing strength. On the other hand, an issue with the mechanical structure that makes up the impulse seal device is that when installing an air blowing device to cool the entire joint, this requires a certain amount of size and may get in the way of the sealing process. The disadvantage was that it reduced workability. Therefore, in order to maintain the quality at a certain level of production efficiency by setting compromises for each of these processing conditions, it was necessary to take measures such as relying on operations by skilled workers. .

Therefore, the present invention eliminates the above-mentioned drawbacks by preferentially cooling the joint part, thereby making it possible to process a seal with a predetermined seal strength at a predetermined production efficiency even when operated by an unskilled person. This is a technical problem to be solved.

(Technical means for solving the problem) The technical means for solving the above problem is to provide a wire or ribbon-shaped heating element between movably opposing seal bars, and to connect the heating element and the seal bar. Insert multiple layers of synthetic resin film or sheet between the two, press and heat both seal bars to seal the multiple layers of synthetic resin film or sheet,
The impulse seal device that fuses the central part of the seal is equipped with air blowing means on the seal bar surface that is close to the heating element during seal bar crimping, or the seal on the side that comes into contact with the heating element during seal bar crimping. - A protruding portion coated with a thin film insulating layer made of a heat-resistant material is provided on the bar surface, and the air blowing means is provided on the protruding portion.

(Function) According to the above configuration, the synthetic resin films or sheets to be joined are inserted between the opposing seal bars with a wire or ribbon-shaped heating element in between, and are crimped by the seal bars. Then, the heating element is electrically heated and bonded. Then, when the power supply is cut off, a command is issued to release the crimping by the seal bar, and air is blown out by the air blowing means, the synthetic resin film or sheet is moved almost to the center line of the joined part. disconnected.

Therefore, the air blown out by the air blowing means according to the present invention is discharged to the atmosphere through the space formed by the synthetic resin film or sheet and the seal bar. In this process, the blown air enters the seal bar body or a space formed by the protrusion provided on the seal bar and the synthetic resin film or sheet, and then passes through the seal bar body. The blown air is discharged to the atmosphere through the gap formed between the edge of the seal bar or the edge of the protrusion on the seal bar and the synthetic resin film or sheet surface, but initially the blown air itself hardly expands in volume. Therefore, the temperature change is small, and the cooling effect is mainly due to forced draft heat transfer, and the cooling temperature is almost determined by the temperature of the supplied air without much difference from the temperature of the blown air. Alternatively, the temperature may be suitable to cut the sheet joint approximately at its center line, and the subsequent blown air is directed to the edges of the seal bar itself or to the edges of the protrusions on the seal bar. It rapidly flows out into a wide external atmospheric space while increasing the flow rate from the narrow gap formed between the edge and the synthetic resin film or sheet, so that it expands adiabatically all at once, lowering the temperature of the blown air itself and reaching the joint of the synthetic resin film or sheet. It exerts a strong cooling effect.

In this manner, the air blown out from the blowing means for cooling has a weak effect on the cut portion to be fused, but has a strong and rational effect on the joint portion where sealing strength must be ensured.

(Example) The configuration of an example of the present invention will be described below with reference to the drawings.

FIG. 1 is a partial sectional view of the main part of the first embodiment.
and 2 are seal bars facing each other through a nichrome wire 3 with a diameter of 0.8 mm that is a heating element, and between the nichrome wire 3 and the seal bar 1 there are two stacked sheets that are workpieces. A dried synthetic resin film 4 is inserted, and a glass fiber-reinforced fluorine-based synthetic resin tape 5 with a thickness of 0.18 mm and a silicon-based synthetic rubber plate 6 with a thickness of 3 mm are placed on the crimp surfaces of the seal bars 1 and 2. It is affixed. A predetermined number of nozzles 7 and 8 having a diameter of 1 mm and serving as air blowing means are provided at a pitch of 30 mm on the faces of the seal bars 1 and 2 that are close to the nichrome wire 3 when the seal bars are crimped. Cooling air is supplied to ducts 9 and 10 formed inside the seal bars 1 and 2 via a solenoid valve 11 from an air supply source (not shown). The seal bars 1 and 2 are crimped by hydraulic or pneumatic pressure controlled by a solenoid valve (not shown), and the synthetic resin film 4 and the nichrome wire 3 are crimped by the seal bars 1 and 2 by a reciprocating mechanism in which the crimping is released by spring bias. Move up and down on the drawing so that it is crimped.

Next, FIG. 2 is a partial sectional view of the main part of the second embodiment, and the blown air is connected to the upper seal bar 1 in the drawing.
The other seal bar 2 merely introduces cooling air into the air duct 10. 3 is a nichrome wire with a diameter of 0.8 mm, 4 is a synthetic resin film to be processed, and 5 is a 0.18 mm diameter
mm thick glass fiber reinforced fluorine based synthetic resin tape, 6
is a silicon-based synthetic rubber plate with a thickness of 3 mm, and the nozzle 7 of the seal bar 1 is connected to the solenoid valve 11 from a pressurized air source (not shown).
The cooling air guided to the air duct 9 is blown out through the air duct 9. The seal bars 1 and 2 are crimped by hydraulic or pneumatic pressure controlled by a solenoid valve (not shown), and the synthetic resin film 4 and the nichrome wire 3 are crimped by the seal bars 1 and 2 by a reciprocating mechanism in which the crimping is released by spring bias. Move up and down on the drawing so that it is crimped.

FIG. 3 is a partial sectional view of the main part of the third embodiment, and FIG.
The figure is a partial perspective view of the main part of the third embodiment, in which air is blown out only from the lower seal bar 2. A protrusion 12 with a height of 2 mm and a width of 6 mm is provided on the upper surface of the lower seal bar 2 in the drawing, and a ceramic coating 13 with a thickness of 0.1 mm is applied to the surface of the protrusion 12, which protrudes parallel to the nichrome wire 3. A nozzle 8 with a diameter of 1 mm is placed on the part 12 at a pitch of 30 mm.
A predetermined number of them are opened and cooling air supplied via the solenoid valve 11 and the air duct 10 is blown out from a pressure air source (not shown). In addition, the seal bar 1 on the upper side in the drawing has a glass fiber-reinforced fluorine-based synthetic resin tape 5 with a thickness of 0.18 mm attached to the sealing surface via a silicon-based synthetic rubber plate 6 with a thickness of 3 mm. An air duct 9 is provided inside facing the film 4 to introduce cooling air. The seal bars 1 and 2 are crimped by hydraulic or pneumatic pressure controlled by a solenoid valve (not shown), and by a reciprocating mechanism in which the crimping is released by spring bias, the synthetic resin film 4 as well as the nichrome wire 3 are crimped by hydraulic or pneumatic pressure. 2
It moves up and down on the drawing so that it is crimped.

Next, the functions common to the above embodiments will be described.
Figure 4 is a time chart of the three types of operations: vertical crimping of the seal bar 1, energizing the nichrome wire 3, and blowing out cooling air. film 4
Also, the energization time of the solenoid valve for controlling the hydraulic or pneumatic means (not shown) for pressing against the seal bar 2 via the nichrome wire 3, the energization time of the nichrome wire 3 which is a heating element, and the time for energizing the nichrome wire 3, which is a heating element, and the time for blowing out cooling air. The opening energization time of the solenoid valve 11 is shown. First, the solenoid valve for hydraulic or pneumatic control is
When the nichrome wire 3 is turned on and the seal bar 1 is pressed against the seal bar 2, the nichrome wire 3 generates heat and melts the two layers of synthetic resin film 4 and joins them together. Although the current is cut off, the seal bars 1 and 2 remain in that state for a while. Then, at the same time as the solenoid valve that presses the seal bar 1 is turned off, the nichrome wire 3 is energized again, so-called dry firing is performed to decompose the resin attached to the nichrome wire 3, and the solenoid for blowing air is turned off. The valve 11 is energized and opened to blow out air. This blown air is applied to the opposing seal bars 1 and 2 and the synthetic resin film 4, which are about to open slightly due to the release of the urging force by the spring (not shown) after the pressure-bonding action by the hydraulic or pneumatic pressure has disappeared. It is discharged into the atmosphere through the gap between the two, cooling the joint 15 at that time. On the other hand, at this point a tensile cutting operation is performed.
In this way, the impulse seal sealing process is completed in step 1.
Cycle. Below, we will discuss the parts that are not common to each of the above embodiments, that is, the operation at the stage when the crimping command to the seal bar is released and the solenoid valve 11 receives an opening command and cooling air is blown out from the nozzle 7 and/or 8. .

Referring to FIG. 1 of the first embodiment, the air blown from the upper nozzle 7 passes through the gap 14 between the seal bar 1 and the synthetic resin film 4 and expands the volume at the joint of the synthetic resin film 4. Cool 15. The air blown from the nozzle 8 enters the space 16 formed by the seal bar 2, the nichrome wire 3, and the synthetic resin film 4, but no strong cooling effect occurs here, and the air is combined with the edge of the next seal bar 2. When passing through the gap 17 with the resin film 4, the joint portion 1
Cool 5.

In the second embodiment, the nozzle is provided only on one side.
Referring to FIG. 2, the air blown from the upper nozzle 7 passes through the gap 14 between the seal bar 1 and the synthetic resin film 4 and cools the joint 15 of the synthetic resin film 4 while expanding its volume.

The third embodiment differs from the second embodiment in that, contrary to the second embodiment, the nozzle is provided only on the lower side, and the nozzle portion is made to protrude. The operation will be explained with reference to FIG. 5, which is an enlarged view of the main part. The surface of the protrusion 12 provided on the upper surface of the seal bar 2 is coated with ceramic, and when the seal bar 1 is crimped onto the seal bar 2, the nichrome wire 3
The synthetic resin film 4 is prevented from welding as well as from metal contact and short circuit.
The air blown out from the nozzle 8 provided on the protrusion 12 enters the space 16 formed by the protrusion 12, the nichrome wire 3, and the synthetic resin film 4, and then reaches the edge of the protrusion 12 and the surface of the synthetic resin film 4. It is discharged into the atmospheric space 18 through a narrow gap 17 formed between the two. In this process, the blown air flows through the seal bars 1 and 2 in the space 16.
is an extension of the previous process in which the synthetic resin film 4 is in a compressed state and is in a compressed storage state, so it does not exert a very strong cooling effect on the cut portion 19 of the synthetic resin film 4.
Next, when it escapes through the gap 17 to the atmospheric space 18, it adiabatically expands all at once, lowering its own temperature, and increasing the flow velocity to strongly cool the joint 15 of the synthetic resin film 4. At this stage, that is, the cutting process, the synthetic resin film 4 is pulled in the direction of the arrow, and the cut portion 1
9, the result is as shown in FIG. 6, but the cut portion 19 still maintains a temperature suitable for fusing operation and is easily, quickly, and cleanly cut, whereas the joint portion 15 has already been cooled down. Since the film is tightly sealed, even if it is subjected to tensile force due to cutting operations, the original sealing strength can be maintained without reducing the film thickness. In contrast to the above, FIGS. 7A and 7B show the joints and cutting states of synthetic resin films according to the prior art, but even if air is blown from the outside (see FIG. 7), it is not possible to sufficiently cool the narrow space 20. This is difficult, and in order to cool the seal bar sufficiently, a device for that purpose must be installed near this area, which reduces work efficiency.Also, even if the seal bar is cooled from inside 9 and 10, the seal bar itself has high thermal resistance. Since the material silicon-based synthetic rubber plate 6 was pasted, the expected cooling effect could not be obtained, and the cutting operation stretched the joint 21 as shown in Figure 7B, making the film thinner, making it impossible to obtain a sufficient seal. It was becoming difficult to maintain strength.

(Effect of the invention) The bag-making process in which multiple synthetic resin films or sheets are stacked and melt-bonded into an extremely narrow band shape to form a so-called seal or bag is the above-mentioned sealing process to form a bag, and a single sheet. The cutting process to make a bag is carried out almost simultaneously, and if the synthetic resin film or sheet is in a state just before melting or solidifying, the cutting process can be easily carried out and a bag with a clean appearance can be made. At the same time, the important joint that forms the bag is stretched and becomes thinner, weakening its strength and reducing its function as a bag.On the other hand, increasing the strength of the joint makes it difficult to cut, resulting in a cut that is not necessarily satisfactory in terms of appearance. does not become
There were two contradictory conditions, and these were weaknesses in the production process. The present invention utilizes the seal bar itself as a cooling air supply duct to cool itself without installing an external cooling device that would interfere with sealing work. In this case, the surface facing the nichrome wire is coated with an insulating layer made of ceramic coating, which has excellent heat resistance and is highly durable, and a small hole or slit-shaped nozzle is provided in this part to draw air. This air blows out the synthetic resin film or sheet, and after passing through the vicinity of the cut section of the synthetic resin film or sheet, it expands adiabatically at the joint and cools it down. By using this, we succeeded in cooling the two parts by creating a temperature difference. The above conflicting conditions were resolved. This has the effect of shortening the process time without increasing it, making it possible to produce a product with high seal strength and a satisfactory appearance. In particular, in the case of materials with high elasticity such as thick synthetic resin sheets and hollow synthetic resin films, the above-mentioned effect is noticeable. If the seal strength (Kawakami method) was to be maintained, the seal efficiency would have been limited to 800 to 1000 seals/hour, but according to the present invention, even if the seal strength was increased to 1100 g, the seal efficiency could be as high as 2000 seals/hour. It became possible to obtain it.

The above seal strength is a national standard.
The measurement method is determined by JIS, but the applicant has established a measurement method that is even stricter as an internal standard and is tailored to the actual usage conditions (upstream method).
Since we have obtained satisfactory measurement data, we have attached an excerpt of the main part for your reference.

[Brief explanation of the drawing]

FIG. 1 is an enlarged partial sectional view of the main part of the first embodiment;
FIG. 2 is an enlarged partial sectional view of the main part of the second embodiment, FIG. 3 is an enlarged partial sectional view of the main part of the third embodiment, and FIG. 4 is a time chart of one cycle of the impulse sealing process. FIG. 6 is an explanatory diagram of a typical seal joint according to the third embodiment and the cut state after joining, FIG. 7 is a partially enlarged cross-sectional view for explaining the prior art, and FIG. 8 is a diagram showing the main points of the third embodiment. FIG. 1, 2... Seal bar, 3... Nichrome wire,
4...Synthetic resin film, 7, 8...Air nozzle, 12...Protrusion, 13...Ceramic coating, 14...Space related to joint, 15...
...Joint part, 16...Semi-closed space related to cutting part, 17...Narrow gap related to joint part, 18...
...Atmospheric space related to the joint, 19...Cut.

Claims (1)

[Claims for Utility Model Registration] 1) A wire or ribbon-shaped heating element 3 is provided between movably opposing seal bars 1 and 2, and a plurality of wire or ribbon-shaped heating elements 3 are provided between the heating element 3 and the seal bars 1 and 2. In an impulse sealing device, a plurality of layers of synthetic resin film or sheet 4 is inserted, both seal bars 1 and 2 are crimped and heated to seal the plurality of layers of synthetic resin film or sheet 4, and the central part of the seal is fused. An impulse seal device characterized in that air blowing means 7 and 8 are provided on the surfaces of the seal bars 1 and 2 that are close to the heating element 3 when the seal bars 1 and 2 are crimped. 2) Of the above-mentioned opposing seal bars 1 and 2,
A protrusion 12 coated with a thin film insulating layer 13 made of a heat-resistant material is provided on the surface of the seal bar 2 that is close to the heating element 3 when the seal bars 1 and 2 are crimped, and an air blowing means 8 is provided on the protrusion 12. An impulse seal device according to claim 1, characterized in that the impulse seal device comprises: