Seal bar and heat seal device

Abstract

To provide a technique that can accurately detect a temperature of a sealing surface, without being influenced by a sealing condition or the like.SOLUTION: A seal bar, in which a sealing surface having a length in a long side direction and a height in a short side direction is formed, comprises two heaters provided to extend in the long side direction inside the seal bar, which transfer heat to the sealing surface and temperature sensors, provided inside the seal bar, which are arranged at positions where the heat transferred from the heaters to the sealing surface passes, where the two heaters are at positions away by the same distance from the sealing surface and the temperature sensors are provided on the two heaters respectively.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a technique for sealing packaging materials and the like. [Background technology]

[0002] For example, in a packaging machine, a seal bar having a sealing surface for thermocompression bonding is used to thermocompress (seal) packaging materials when forming packages such as candy bags. In order to obtain a good seal at the thermocompression bonding point of the packaging material, it is preferable to directly detect and control the temperature of the sealing surface with a temperature sensor. However, if a temperature sensor is provided on the sealing surface for this purpose, the smoothness of the sealing surface will decrease, which will have an adverse effect on the sealing condition of the packaging material.

[0003] Therefore, in the past, in temperature control of the sealing surface, the temperature of a surface of the sealing bar other than the sealing surface was detected rather than directly detected (for example, Patent Document 1). Alternatively, a temperature sensor was inserted into the sealing bar from the side that intersects with the short side of the sealing surface to detect the temperature inside the sealing bar. Specifically, a heater was provided inside the sealing bar extending in the extension direction of the sealing bar, and the temperature sensor was inserted into the sealing bar in the same direction as the extension direction of the heater. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5423078 Summary of the Invention [Problem to be solved by the invention]

[0005] However, if the temperature is detected at a position other than the position on the seal surface, the difference between the detected temperature and the actual temperature of the seal surface will vary depending on the sealing conditions (seal bar structure, sealing (thermocompression) repetition speed, ambient temperature, etc.) For this reason, simply setting an offset value to correct the temperature detected by the temperature sensor will not allow for proper temperature control of the seal surface.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a technique for detecting the temperature of a seal surface with high accuracy, without being affected by sealing conditions or the like. [Means for solving the problem]

[0007] The present invention is, for example, a seal bar having a seal surface with a length in the long side direction and a height in the short side direction, and including a heater extending inside the seal bar in the long side direction and transmitting heat to the seal surface, and a temperature sensor inside the seal bar positioned so that the heat transmitted from the heater to the seal surface passes through, with two heaters positioned at approximately the same distance from the seal surface and one temperature sensor provided for only one of the two heaters. With this configuration, the temperature of the seal surface can be detected with high accuracy without being affected by sealing conditions, etc. [Effects of the Invention]

[0008] According to the present invention, it is possible to detect the temperature of the sealing surface with high accuracy without being affected by the sealing conditions or the like. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a perspective view conceptually showing a heat sealing device according to a first embodiment. [Figure 2] FIG. 2 is a side view conceptually showing a heat sealing device. [Figure 3] FIG. 2A is a plan view of a seal bar provided in a heat sealing device, viewed from the sealing surface side, and FIG. 2B is a plan view of the seal bar, viewed from the upper end surface side. [Figure 4]FIG. 1 is a graph of data obtained by the present inventors. [Figure 5] FIG. 1 is a block diagram conceptually showing the configuration of a heat sealing device. [Figure 6] FIG. 10 is a side view conceptually showing a heat-sealing device according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment in which the present invention is applied to a heat sealing device provided in a packaging machine or the like will be specifically described with reference to the drawings.

[0011] [1] First embodiment 1 and 2 are a perspective view and a side view, respectively, conceptually illustrating a heat-sealing device according to a first embodiment. As shown in FIGS. 1 and 2, the heat-sealing device includes a pair of seal bars 1 arranged opposite each other, with a seal surface 11a formed on each opposing surface 111. The pair of seal bars 1, in a heated state, clamp and press the packaging material passing between them to thermocompress the packaging material and form a package such as a confectionery bag. Note that in FIG. 2, the pair of seal bars 1 are bilaterally symmetrical, and only the seal bar 1 on the right side is labeled with a reference number.

[0012] Specifically, each sealing bar 1 has a rod-shaped body 11 having a sealing surface 11a, a cutting blade 12 used to cut the packaging material at the thermocompression bonding location, a heater 13, and a temperature sensor 14.

[0013] The cutting blade 12 has a flat blade shape and is provided on the main body 11 with the width direction of the cutting edge 12a aligned with the extension direction D1 (see FIG. 1) of the main body 11. More specifically, a groove 11b capable of accommodating the cutting blade 12 is formed in the opposing surface 111, and the cutting blade 12 is provided so as to be able to reciprocate between a protruding position where the cutting edge 12a protrudes from the opposing surface 111 and a retracted position where the cutting edge 12a is accommodated in the groove 11b. The reciprocating movement of the cutting blade 12 is performed by a drive unit 2 (see FIG. 5) provided in the heat sealing device.

[0014] FIG. 3(A) is a plan view of the seal bar 1 from the sealing surface 11a (opposing surface 111) side. As shown in FIG. 3(A), the opposing surface 111 has a sealing surface 11a provided on both sides (top and bottom in this embodiment) of the groove 11b. Each sealing surface 11a has a rectangular shape extending in the extension direction D1 of the main body 11. As shown in FIGS. 2 and 3(A), the main body 11 of the seal bar 1 further has an upper end surface 112 intersecting with the upper side 11c (upper long side) of the upper sealing surface 11a and a lower end surface 113 intersecting with the lower side 11d (lower long side) of the lower sealing surface 11a. In this embodiment, the upper end surface 112 and the lower end surface 113 are formed approximately perpendicular to the sealing surface 11a (opposing surface 111).

[0015] The heater 13 is rod-shaped and thinner than the main body 11 of the seal bar 1, and is provided inside the main body 11 with its extending direction aligned with the extending direction D1 of the main body 11. Specifically, the heater 13 is provided at a position overlapping each of the upper and lower two sealing surfaces 11a in the plan view shown in Fig. 3(A).

[0016] FIG. 3(B) is a plan view of the seal bar 1 from the upper end surface 112 side. As shown in FIG. 3(B), a perforation 112a that leads to the inside of the main body 11 of the seal bar 1 is provided in the upper end surface 112. Specifically, the perforation 112a is formed so as to reach a position between the sealing surface 11a and the corresponding heater 13 (see FIGS. 2 and 3(A)). More specifically, the perforation 112a extends in a direction D2 that is perpendicular to the extension direction D1 of the main body 11 and along the sealing surface 11a so as to reach such a position. In this embodiment, the perforation 112a extends in a direction perpendicular to the upper end surface 112. Note that in this embodiment, a perforation 112a that leads to the inside of the main body 11 of the seal bar 1 is also provided in the lower end surface 113, similar to the perforation 112a provided in the upper end surface 112.

[0017] 3(A), the temperature sensors 14 are sensors such as thermocouples, and are inserted one by one into perforations 112a provided in the upper end face 112 and the lower end face 113, respectively, so that their tips reach predetermined positions inside the main body 11. That is, the temperature sensors 14 are inserted into the main body 11 from the upper end face 112 and the lower end face 113, respectively. As a result, inside the main body 11, each temperature sensor 14 is provided at a position between the sealing surface 11a, the temperature of which is to be detected by the temperature sensor 14, and the heater 13 corresponding to it.

[0018] With this type of heat sealing device, when heat is transferred from the heater 13 to the sealing surface 11a, the heat passes around the temperature sensor 14. Therefore, the temperature detected by the temperature sensor 14 is likely to correspond to the actual temperature of the sealing surface 11a without being affected by sealing conditions (such as the structure of the seal bar, the repetition rate of sealing (thermocompression bonding), and the ambient temperature). For example, the ratio of the heat transferred to the temperature sensor 14 to the heat transferred to the sealing surface 11a tends to be approximately constant, without being affected by sealing conditions. Therefore, with the above-described heat sealing device, it is possible to accurately detect the temperature of the sealing surface 11a without being affected by sealing conditions.

[0019] From the perspective of enabling such temperature detection of the seal surface 11a, the inventors obtained various data, which will be described later, and based on that data, optimized the position and size of the temperature sensor 14 inside the main body 11 of the seal bar 1. Figure 4 is a graph of the data obtained by the inventors.

[0020] The inventors prepared temperature sensors 14 with diameters dm of 1 mm and 1.6 mm. By changing the positions of the boreholes 112a into which they were inserted, the temperature sensors 14 with diameters dm of 1 mm were positioned so that the distance L1 (see FIG. 2 ) from the seal surface 11a in the direction perpendicular to the seal surface 11a was 1 mm, 3 mm, and 5 mm, respectively. The temperature sensors 14 with diameters dm of 1.6 mm were positioned so that the distance L1 was 3 mm and 5 mm, respectively. For comparison, a conventional temperature sensor (with a diameter of 3 mm) was inserted into the seal bar from the side intersecting the short side of the seal surface 11a, and by changing the insertion position, the conventional temperature sensor was positioned so that the distance L1 was 1 mm, 3 mm, and 5 mm, respectively. During sealing, the temperature at each position was measured by each temperature sensor, and the actual temperature of the seal surface 11a was measured by another temperature sensor. FIG. 4 shows a graph of the relationship between the distance L1 from the seal surface 11a and the temperature difference ΔT between the actual temperature of the seal surface 11a and each temperature sensor.

[0021] From the graph shown in Figure 4, the inventors have found the optimization conditions for the position and size of the temperature sensor 14. Specifically, with a conventional temperature sensor, the temperature difference ΔT is about 10°C regardless of the distance L1 from the sealing surface 11a, whereas with the temperature sensor 14 and its arrangement proposed by the inventors, the temperature difference ΔT is 4°C or less. Therefore, the inventors have found the following conditions, with the temperature difference ΔT being 4°C or less as the optimization condition.

[0022] As a first condition, it is preferable that the temperature sensor 14 be disposed at a position where the distance L1 (see FIG. 2) from the sealing surface 11a in the direction perpendicular to the sealing surface 11a is 5 mm or less. More preferably, the temperature difference ΔT is 2°C or less. In this case, for a temperature sensor 14 with a diameter dm of 1.6 mm, the condition is that the temperature sensor 14 be disposed at a position where the distance L1 is 3 mm or less. Note that for a temperature sensor 14 with a diameter dm of 1 mm, the condition is that the temperature sensor 14 be disposed at a position where the distance L1 is 5 mm or less, as in the case where the optimization condition is that the temperature difference ΔT is 4°C or less.

[0023] As a second condition, it is preferable that the diameter dm of the temperature sensor 14 is less than 3 mm.

[0024] Although not shown in FIG. 4, the inventors have also found the following conditions for detecting the temperature of the seal surface 11a with high accuracy.

[0025] As a third condition, it is preferable that the temperature sensor 14 be disposed at a position where the distance L2 (see FIG. 2) from the upper end face 112 (or the lower end face 113) in the direction D2 perpendicular to the extension direction D1 of the main body 11 and along the sealing surface 11a is equal to or greater than the insertion depth dp (L2≧dp) determined by the diameter dm of the temperature sensor 14. As an example, the insertion depth dp can be set to six times the diameter dm.

[0026] As a fourth condition, in a plan view (see FIG. 3(A)) from the side of the sealing surface 11a (opposing surface 111) of the main body 11 of the seal bar 1, it is preferable that the temperature sensor 14 be disposed at a position between a center line m1 and an auxiliary line m2 that are substantially parallel to the long sides of the sealing surface 11a that is the target of temperature detection (in this embodiment, the upper side 11c of the upper sealing surface 11a and the lower side 11d of the lower sealing surface 11a). Here, the center line m1 is an imaginary line that bisects each sealing surface 11a, and the auxiliary line m2 is an imaginary line that further bisects the area between each long side of each sealing surface 11a and the center line m1.

[0027] As a fifth condition, when viewed in a plane from the sealing surface 11a (opposing surface 111) side relative to the main body 11 of the sealing bar 1, it is preferable that the temperature sensor 14 be arranged within the area (sealing execution area) of the sealing surface 11a that abuts against the sealing target such as packaging material.

[0028] Figure 5 is a block diagram conceptually showing the configuration of a heat-sealing device. As shown in Figure 5, the heat-sealing device further includes a drive unit 2 and a control unit 3 in addition to the pair of seal bars 1 described above. The drive unit 2 is a drive mechanism that causes the seal bars 1 to perform operations such as opening and closing when thermocompressing the packaging material, and cutting (moving from a retracted position to a protruding position) of the cutter blade 12 when cutting the packaging material.

[0029] The control unit 3 controls at least the drive unit 2 and the heater 13. Specifically, the control unit 3 controls the drive unit 2 in accordance with a predetermined operation program, causing the drive unit 2 to repeatedly perform a sealing operation to thermocompress the packaging material. The control unit 3 also controls the heater 13 based on the temperature T detected by the temperature sensor 14, thereby bringing the temperature of the sealing surface 11a to a desired temperature.

[0030] As described above, according to the heat sealing device of this embodiment, the temperature detected by the temperature sensor 14 is more likely to correspond to the actual temperature of the sealing surface 11a without being affected by sealing conditions, etc. Therefore, temperature changes on the sealing surface 11a are more likely to appear in the temperature T detected by the temperature sensor 14, and therefore temperature changes on the sealing surface 11a can be detected with high accuracy. Therefore, temperature changes on the sealing surface 11a are more likely to be reflected in the control of the heater 13 based on the temperature T detected by the temperature sensor 14, and as a result, the temperature of the sealing surface 11a can be controlled with high accuracy.

[0031] [2] Second embodiment Fig. 6 is a side view conceptually showing a heat-sealing device according to a second embodiment. As shown in Fig. 6, in each seal bar 1, the upper end surface 112 and the lower end surface 113 may be formed so as to be inclined with respect to the sealing surface 11a (opposing surface 111). In this case, perforations 112a are provided in each of the inclined upper end surface 112 and lower end surface 113, and the distance L2 is the distance in the direction D2 from the opening positions of the perforations 112a in each of the upper end surface 112 and lower end surface 113.

[0032] [3] Other embodiments In the heat-sealing device described above, the temperature sensors 14 are not limited to being provided one for each of the upper and lower sealing surfaces 11 a, but may be provided only one for either one of the sealing surfaces 11 a. Furthermore, the number of temperature sensors 14 provided for each sealing surface 11 a is not limited to one, and multiple sensors may be provided.

[0033] The seal bar 1 is not limited to one equipped with a cutting blade 12, but can be modified into various configurations in which at least one seal surface 11a is formed. Furthermore, the heat sealing device described above is not limited to one equipped with a pair of seal bars 1, but may also be one equipped with only one seal bar 1. Furthermore, the heat sealing device is not limited to one that applies thermocompression bonding (sealing) to packaging materials, but can also be used when vacuum sealing electronic devices with exterior members, etc. [Explanation of symbols]

[0034] 1 seal bar 2 Drive unit 3. Control Unit 11 Main unit 11a sealing surface 11b Groove 11c Top 11d bottom edge 12 cutting blades 12a cutting edge 13 Heater 14 Temperature Sensor 111 Opposite surface 112 Upper end surface 112a perforation Lower end surface of 113 D1 extending direction D2 direction dm diameter dp insertion depth L1, L2 distances m1 center line m2 auxiliary line T detected temperature

Claims

1. A seal bar having a seal surface formed thereon, the seal surface having a length in the long side direction and a height in the short side direction, a heater provided inside the seal bar and extending in the long side direction, the heater transmitting heat to the seal surface; a temperature sensor provided inside the seal bar and arranged at a position through which heat is transferred from the heater to the seal surface; A seal bar having two heaters positioned at approximately the same distance from the sealing surface, and one temperature sensor provided for only one of the two heaters.

2. The seal bar of claim 1 , wherein the temperature sensor is positioned near the center of the position of the sealing surface and the position of the heater.

3. The seal bar according to claim 1 or 2, wherein the temperature sensor is positioned near the center of the sealing surface in the height direction, or at a position between the center line of 1 / 2 and the auxiliary line of 1 / 4 in the height direction of the sealing surface.

4. The seal bar according to any one of claims 1 to 3, a control unit that controls the heater based on the temperature detected by the temperature sensor; A heat sealing device comprising:

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