JP2010214855A - Heat sealing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat sealing device capable of confirming difference between set temperature and actual temperature of a seal surface, accurately figuring out reduced temperature of the seal surface and heating response when continuous sealing work is carried out, and preventing problems such as sealing failure caused by decrease in temperature and deterioration of heat distribution on the sealing surface. <P>SOLUTION: The heat sealing device has a seal head to which at least a heater block and a seal bar are joined. A film and a sealant is heated by pressing the heated seal bar on them, and the temperatures of the film and the sealant are increased to around the melting temperature for heat-welding films or a film and a container etc. One or more temperature-measuring thermocouples are provided just proximally to the sealing surface of the seal bar in the longitudinal-width direction of the seal bar, separately from a temperature-controlling thermocouple of the heater block. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a heat sealing apparatus that heats a film or sealant with a heated seal bar to raise the temperature of the film or sealant to near the melting temperature and heat-bonds the films to each other, the film and the container, or the like.

  In the heat seal device that heats the film and sealant by pressing the heated seal bar and raises the temperature of the film and sealant to near the melting temperature, and heat-welds the films to each other, the film and the container, etc. In particular, it is very important to control the temperature of the seal bar when performing the sealing operation.

  Conventionally, the temperature control of the seal bar is actually controlled by measuring the temperature at a location away from the seal surface of the seal bar, that is, the temperature in the vicinity of the heat block by a temperature measuring means such as a thermocouple. . However, there is a problem that the temperature is actually greatly different between the seal surface temperature of the seal bar and the position of the temperature measuring means for control.

  Therefore, if the production conditions in the heat seal device are determined based on the offline seal conditions, the actual seal surface temperature in continuous operation will deviate from the proper seal condition temperature, and the product will be normal. It is often not possible to make.

  Therefore, it is possible to grasp the temperature change of the seal bar in the seal by directly measuring the seal surface temperature of the seal bar. However, if a thermocouple is embedded in the immediate vicinity of the seal surface, the heat distribution on the seal surface is poor. As a result, problems such as defective sealing occur.

  Therefore, it is conceivable that the thermocouple is attached to the sealing surface in the vicinity of the sealing surface with a heat-resistant tape or the like. However, the seal bar is usually at a high temperature of 200 ° C. or more. May not function.

  In addition to this, even if a thermocouple can be attached in the immediate vicinity of the seal bar, if the thermocouple in the immediate vicinity of the seal bar is used for temperature control, the temperature of the heater will not be stable because the temperature fluctuates drastically. A malfunction occurs.

  In this way, it is difficult to attach a thermocouple in the immediate vicinity of the seal bar, so every time you seal, the set temperature of the heater is gradually raised to make the temperature of the seal surface as constant as possible A temperature control method has been proposed. For example, in Patent Document 1, the temperature dependence of the seal strength and the shot dependence of the seal strength are investigated, and the number of shots (n) and the temperature decrease range (δ) from when the operation is stopped until the seal strength is stabilized when the operation is resumed. The desired seal temperature (T) is set as an initial value in a stopped state, and a temperature of δ / n is added and input every shot, and the control temperature is set to T + δ after n shots. A seal temperature control technique that maintains temperature control is disclosed.

  By adopting the above-described temperature control method, the temperature of the seal surface certainly does not fluctuate as compared with normal temperature control. However, even in this case, it is not known how much the actual seal surface temperature has decreased. Furthermore, the responsiveness changes greatly depending on the distance from the sealing surface of the thermocouple for temperature control, and there is a problem that stable control is difficult.

JP 2004-189324 A

  The present invention has been made in view of the above circumstances, and can confirm the temperature difference between the set temperature and the actual seal surface, and can accurately grasp the temperature drop and the heat responsiveness of the seal surface when performing continuous sealing work. It is an object of the present invention to provide a heat seal device capable of preventing problems such as a seal failure due to a temperature decrease on the seal surface and a deterioration in heat distribution.

  The invention according to claim 1 of the present invention has a seal head in which at least a heater block and a seal bar are joined, and heats the film or sealant by pressing the heated seal bar, thereby melting the temperature of the film or sealant. In a heat seal device that heat-bonds films and films to containers, etc. by raising the temperature to near the temperature, a thermocouple for temperature measurement, close to the seal surface of the seal bar, separately from the thermocouple for temperature control of the heater block Is provided in the longitudinal width direction of the seal bar.

  The invention according to claim 2 of the present invention is characterized in that the thermocouple for temperature measurement is fixed to the seal bar by means of bonding having high thermal conductivity. Device.

  The invention according to claim 3 of the present invention is characterized in that the thermocouple for temperature measurement is sandwiched by means for continuously applying a constant force in the normal direction of the seal bar on the side surface of the seal bar. The heat sealing apparatus according to claim 1.

  In the heat seal device of the present invention, apart from the temperature control thermocouple, the temperature of the actual seal surface is close by having one or more temperature measurement thermocouples in the longitudinal width direction of the seal bar in the immediate vicinity of the seal surface. Since the temperature can be measured, the actual temperature of the seal surface can be grasped.

  This makes it possible to confirm the difference between the set temperature and the actual seal surface temperature, and more accurately know how much the temperature of the seal bar decreases and stabilizes when continuous sealing is performed. It becomes possible.

  In addition, when determining the sealing conditions for a new product based on this data, first the sealing temperature conditions are determined by a test sealing machine, and then the sealing temperature suitable for the product in the heat sealing apparatus of the present invention. It becomes possible to grasp the conditions accurately.

  As a result, it becomes possible to prevent a sealing failure caused by a decrease in the seal strength of the product accompanying a decrease in the temperature of the seal bar when continuously sealed.

  In addition, until now, in order to find the sealing conditions for new products, various temperature conditions were set and performance evaluations were performed, which took time and money. By using the heat seal device of the present invention, the seal surface temperature of the heat seal device of the present invention can be matched to the seal temperature condition of a new product test seal machine, so accurate manufacturing conditions can be easily obtained. And time and costs can be greatly reduced.

  Furthermore, the heat seal device of the present invention is provided with a plurality of temperature measuring thermocouples in the immediate vicinity of the seal surface, so that the seal bar surface temperature of the unsealed part such as when a foreign object is caught in the seal bar. Can be confirmed to rise unnaturally. Therefore, by detecting this, it can be utilized as a heat seal device having a sealing failure detection function.

Schematic which showed an example of the installation position of the thermocouple in the conventional heat seal apparatus. Schematic which showed an example which fixed the thermocouple for temperature measurement to the seal bar using the means for adhesion in the heat seal device of the present invention. The heat seal apparatus of this invention WHEREIN: The schematic of an example by which the thermocouple for temperature measurement is clamped by the seal bar side surface. The heat sealing apparatus of this invention WHEREIN: The explanatory view which showed an example which detects the foreign material biting which installed the thermocouple for temperature measurement on the seal bar side surface.

  The heat sealing apparatus of the present invention will be described below based on one embodiment.

  FIG. 1 shows an example of an installation position of a thermocouple in a conventional heat sealing apparatus. A cartridge heater is inserted into the heater block 2 or the seal bar 1 is fixed to a cast-in heater block. The temperature control thermocouple 3 for controlling the temperature of the seal bar 1 is a side surface of the heater block 2 as shown in FIG. 1A or a seal surface of the seal bar 1 as shown in FIG. It is installed in a place away from 5. FIG.1 (c) is the schematic seen from the side cross section.

  FIG. 2 shows a state in which the thermocouple 10 for temperature measurement is fixed by the bonding means 11 having high thermal conductivity near the seal surface of the seal bar. The thermocouple 10 for temperature measurement is attached to the seal bar. Using a thin thermocouple that is in close contact with a small heat capacity and using an adhesive having a high thermal conductivity such as a silver paste, the bonding is performed securely. In addition, the amount of adhesive may be uneven depending on the location, and if the amount of adhesive is too much, the heat of the seal bar may be taken away, and the location where the adhesive is bonded also causes errors. It is necessary to pay attention to the situation.

  FIG. 3 shows a specific example in which the thermocouple 10 for temperature measurement is sandwiched by the side surface of the seal bar 1 by means for continuously applying a constant force from the normal direction of the seal bar. Here, the thermocouple 10 for temperature measurement has a mechanism that uses a thin thermocouple that is in close contact with the seal bar 1 and has a small heat capacity, and presses the thermocouple 10 with a certain force by the pressing block 12. The pressing block 12 is preferably a material having a small thermal conductivity and a small heat capacity, and does not accumulate heat from the thermocouple 10 for temperature measurement. In this example, the spring 13 is used as the thermocouple pressing means, but the same effect can be obtained by pressing the thermocouple using compressed air. 3 (a) and 3 (b) show differences in whether the thermocouple pressing mechanism is attached to the side surface or the bottom surface of the seal bar 1, respectively.

FIG. 4 is an example in which a plurality of temperature measuring thermocouples 10 are attached to the side of the seal bar immediately adjacent to the seal surface 5, and FIG. 4 (a) shows a case where the foreign matter 20 is present on the lower seal bar before sealing. Show. FIG. 4B shows a state in which the upper seal bar is lowered and sealed, and shows a state in which the foreign matter 20 is caught. If sealing is performed continuously in this state, the heat originally taken away by the film or the like is not taken away by the foreign matter portion, so that the temperature of the unsealed portion rises. Although it is difficult to capture this influence at the position of the temperature control thermocouple 3 in the conventional heat seal apparatus, in the heat seal apparatus of the present invention, a plurality of temperature measurement thermocouples 10 are provided on the seal bar 1 immediately adjacent to the seal surface 5. Therefore, if there is a portion that is not sealed, the temperature immediately rises and it is possible to detect a sealing failure.

  Since the heat sealing apparatus of the present invention has the above-described configuration, it performs continuous and stable heat sealing such as a bag making machine for food and pharmaceutical packaging bags and a sealing machine for food cup containers. It can be used as a heat seal device.

DESCRIPTION OF SYMBOLS 1 ... Seal bar 2 ... Heater block 3 ... Thermocouple for temperature control
4 ... Heater terminal 5 ... Sealing surface 10 ... Thermocouple for temperature measurement
11 ... Adhesive 12 ... Pressing block 13 ... Spring
14 ... Fixing jig 20 ... Foreign matter

Claims (3)

  At least a heater block and a seal bar are joined to each other, and the film and sealant are heated by pressing the heated seal bar to raise the temperature of the film and sealant to near the melting temperature. In the heat sealing apparatus for thermally welding the container and the like, apart from the temperature control thermocouple of the heater block, one thermocouple for temperature measurement is provided in the longitudinal width direction of the seal bar in the immediate vicinity of the seal surface of the seal bar. A heat sealing apparatus comprising the above.   The heat sealing apparatus according to claim 1, wherein the temperature measuring thermocouple is fixed to the seal bar by an adhesive means having high thermal conductivity.   The heat sealing apparatus according to claim 1, wherein the thermocouple for temperature measurement is sandwiched by means for continuously applying a constant force on the side surface of the seal bar from the normal direction of the seal bar.

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