Heat bar

Abstract

This invention provides a heat bar that allows heat sealing to be performed in a single sealing process, even when there are steps or unevenness in the part of the packaging material to be sealed, thereby improving the quality of the seal. [Solution] The heat sealing device 10 has a pair of heat bars 11 facing each other with the packaging bag B in between, and the heat bar 11 is composed of a heat bar body 20 and a facepiece 21 equipped with a sealing surface 12. The facepiece is composed of a high thermal conductivity rubber material 23, a carbon graphite sheet 24 sandwiched between the high thermal conductivity rubber material and the heat bar body, and a high heat-resistant sheet arranged on the sealing surface side. When the packaging bag B is a gusset bag with a sleeve gusset 1, when heat sealing is performed, first the high thermal conductivity rubber material is crushed and the sealing surface facing the four-layer portion Q sinks in, and then the high thermal conductivity rubber material is further crushed to absorb the step difference 2 between the four-layer portion Q and the two-layer portion W.

Description

[Technical Field]

[0001] The present invention relates to a heat bar included in a heat sealing device. [Background Art]

[0002] Conventionally, a heat bar included in a heat sealing device is formed of a substantially prismatic body made of metal. When a pair of heat bars are arranged to face each other, mutually opposing side surfaces of the paired heat bars are each provided with a sealing surface. A film-shaped packaging material is sandwiched between mutually opposing sealing surfaces, and the heat sealing device presses the heat bars against each other, whereby a packaging bag is formed from the packaging material or the mouth of the packaging bag is sealed. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] No citation [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] When a flat bag is formed by folding a packaging material in two, or when sealing the mouth of a flat bag formed in this way, the film material has a two-layer structure in which two films are stacked, so the sealing surface of the heat bar can uniformly apply heat and pressure to the sealed portion to be welded such as the bag mouth and side edges. On the other hand, there are known packaging bags that form gussets by folding predetermined parts of the folded packaging material, such as self-standing bags with a bottom gusset created by folding the bottom of the bag, or gusseted bags with sleeve gussets created by folding the side edges. In such packaging bags, because of the folded film material, as shown in Figure 5 or Figure 6, a two-layer section W where two layers of film material are stacked and a four-layer section Q where four layers are stacked are created in the area to be sealed. If the packaging bag B is heat-sealed using a conventional heat bar to match the thickness of the four-layer section Q, there is a risk of insufficient heat and pressure on the two-layer section W, resulting in a sealing failure. On the other hand, if the heat bar is heat-sealed to match the thickness of the two-layer section W, there is a risk of excessive heat and pressure on the four-layer section Q, resulting in a sealing failure. In either case, with conventional heat bars where the sealing surface is configured to be flush, it is extremely difficult to properly seal the area to be sealed where there is a step. Therefore, in order to suppress the occurrence of such welding defects, in the case of standing bags or gusset bags, one sealing surface of the opposing heat bars is configured as a conventional flush sealing surface structure, and a cushioning material with low thermal conductivity and elasticity, such as silicone resin, is attached to the other sealing surface. When the opposing sealing surfaces are pressed against each other, heat sealing is performed on one side at a time, causing heat to press together on one side and deforming the other side to eliminate the step between the four layers and the two layers. This method of heat-sealing each side individually requires the application of heat and pressure to the packaging material at least twice, complicating and making the sealing process cumbersome. Furthermore, because heat is applied to the packaging material multiple times, the thermal history related to the sealing process becomes higher, which may cause deterioration of the packaging material, and may also make temperature control based on the heat involved in the sealing process difficult.

[0005] Therefore, the problem that the present invention aims to solve is to provide a heat bar that can perform heat sealing in a single sealing process even when there is a step in the part of the packaging material to be sealed, thereby improving the quality of the seal. [Means for solving the problem]

[0006] The heat bar described in claim 1 is a heat bar provided in a heat sealing device, The heat bar comprises a faceplate with a sealing surface that deforms in response to an applied external force, It consists of a heat bar body to which the facepiece is fixed, When the sealing surface of the facepiece is pressed against the surface of the packaging material to be sealed, The sealing surface is characterized by deforming to conform to any irregularities that occur on the surface to be sealed.

[0007] The heat bar described in claim 2 is characterized in that, in the invention described in claim 1, the facet portion is made of a highly thermally conductive rubber material formed in a sheet shape of a predetermined thickness.

[0008] The heat bar according to claim 3 is: In the invention according to claim 1, the surface portion is formed in a prismatic shape by accumulating a plurality of members whose direction of movement is restricted to the thickness direction, and comprises an integrated pillar having a sealing surface on its front, A cushioning material is placed between the back of the integrated pillar and the heat bar body, It is characterized by being composed of the following.

[0009] The heat bar according to claim 4 is the integrated pillar in the invention according to claim 3, wherein a plurality of convex-shaped thin metal plates are stacked and arranged so as to be convex toward the front, The heat bar body is formed to surround the aforementioned integrated pillar, and has a cross-sectional shape in the thickness direction that is substantially U-shaped. The sealing surface formed on the protrusion of the integrated pillar is characterized in that it is exposed from an open end formed on the front surface of the heat bar body.

[0010] The heat bar according to claim 5 is characterized in that, in the invention according to claim 3, the cushioning material is made of rubber.

[0011] The heat bar according to claim 6 is characterized in that, in the invention according to claim 3, the cushioning material is a flexible synthetic resin material.

[0012] The heat bar according to claim 7 is the invention according to claim 1, wherein the facet portion comprises a surface film having a sealing surface, It consists of a thin film core material that has been folded multiple times at a predetermined angle, The back surface of the core material is placed in front of the heat bar body, and the surface film is placed on the front side of the core material. When viewed in cross-section along the thickness direction of the aforementioned facet, a truss structure is formed in which gaps divided into approximately triangular sections are continuously arranged. The gap is characterized by being filled with a flexible filler material.

[0013] The heat bar according to claim 8 is characterized in that, in the invention according to claim 7, the surface film and the core material are made of metal foil.

[0014] The heat bar according to claim 9 is characterized in that, in the invention according to claim 7, the surface film and the core material are made of a carbon graphite sheet.

[0015] The heat bar according to claim 10 is characterized in that, in the invention according to claim 7, the filler is a synthetic resin material. [Effects of the Invention]

[0016] The heat bar according to the present invention consists of a heat bar body and a facepiece fixed to the heat bar body. The facepiece is provided with a sealing surface that deforms in response to an applied external force, so that when the heat bar is pressed against the packaging material, the sealing surface deforms to match the irregularities in the packaging material. This allows heat sealing to be performed in a single sealing process, even if there are steps or unevenness in the sealing surface. Therefore, even if there are steps or unevenness in the sealing surface of the packaging material, heat sealing can be performed in a single sealing process, improving the sealing quality. Preferably, the facepiece is made of a highly thermally conductive rubber material formed into a sheet of a predetermined thickness. This provides elasticity to the facepiece, allowing the sealing surface to deform in response to external forces. In addition, the highly thermally conductive rubber material has a higher thermal conductivity than ordinary rubber material. Therefore, heat from the heat bar body can be conducted through the inside of the highly thermally conductive rubber material and along the thickness direction of the rubber material to the sealing surface, so that the entire sealing surface can be heated evenly. Preferably, the facet portion is composed of a stacked pillar formed by stacking multiple members whose movement direction is restricted to the thickness direction to create a rectangular prism shape, and a cushioning material placed between the stacked pillar and the heat bar body. Particularly preferably, the stacked pillar is constructed by stacking multiple convex-shaped thin metal plates, and the stacked pillar, which is arranged to be convex toward the front side, is surrounded by a heat bar body whose cross-sectional shape along the thickness direction is substantially U-shaped. This allows the sealing surface formed on the front of the convex portion of the stacked pillar to be exposed through a gap formed on the front side of the heat bar body, and when the surface to be sealed of the packaging material is pressed against this sealing surface, the multiple thin metal plates constituting the stacked pillar slide along the thickness direction in accordance with the irregularities formed on the surface to be sealed, so that the sealing surface can follow the irregularities of the surface to be sealed. More preferably, the packing material is composed of a core member obtained by bending a planar face portion a plurality of times at a predetermined angle arranged on the front surface of the heat bar, and a surface plate arranged on the front side of the core member, wherein a cross-sectional shape along the thickness direction forms a truss structure, and a flexible filler is filled into a plurality of gaps partitioned by the truss structure. This ensures a predetermined strength in the thickness direction, and when a predetermined pressure is applied, the truss structure bends, allowing the sealing surface to follow the irregularities formed on the surface to be sealed. [BRIEF DESCRIPTION OF THE DRAWINGS]

[0017] [Figure 1] It is an explanatory diagram schematically showing the configuration of a heat sealing apparatus provided with the heat bar according to the first embodiment. [Figure 2] It is a side view schematically showing the configuration of the heat bar according to the first embodiment. [Figure 3] It is a perspective view schematically showing the configuration of the heat bar according to the first embodiment. [Figure 4] It is a front view schematically showing the configuration of the heat bar according to the first embodiment. [Figure 5] It is a perspective view showing an example of a packaging bag to be heat-sealed by the heat sealing apparatus provided with the heat bar according to the first embodiment. [Figure 6] It is a cross-sectional plan view showing an example of a packaging bag to be heat-sealed by the heat sealing apparatus provided with the heat bar according to the first embodiment. [Figure 7] It is a cross-sectional plan view schematically showing a state where heat sealing is performed by the heat sealing apparatus provided with the heat bar according to the first embodiment. [Figure 8] It is a side view schematically showing the configuration of the heat bar according to the second embodiment. [Figure 9] It is a perspective view schematically showing the configuration of the heat bar according to the second embodiment. [Figure 10] It is a cross-sectional plan view schematically showing a state where heat sealing is performed by the heat sealing apparatus provided with the heat bar according to the second embodiment. [Figure 11] It is a side view schematically showing the configuration of the heat bar according to the third embodiment. [Figure 12] This is a perspective view showing a schematic configuration of the heat bar according to the third embodiment. [Figure 13] This is a schematic plan view cross-sectional view showing a heat sealing device equipped with a heat bar according to the third embodiment when heat sealing is performed. [Example 1]

[0018] An embodiment of the heat bar according to the present invention will be described with reference to the attached drawings. Figure 1 is an explanatory diagram showing a schematic configuration of a heat sealing device having the heat bar according to this embodiment, and Figures 2 to 4 are explanatory diagrams showing a schematic configuration of the heat bar according to this embodiment.

[0019] As shown in Figure 1, the heat sealing device 10 has a pair of heat bars 11, 11 with their sealing surfaces 12 facing each other, a heat source 13 for heating each heat bar 11, and arms 14, 14 that can move toward and away from the heat bars 11, 11 supported at their tips. The heat sealing device 10 is configured such that a heat bar 11 heated by a heat source 13 sandwiches the overlapping portions to be sealed of heat-sealable packaging materials between the sealing surfaces 12, thereby sealing, for example, the opening of a packaging bag B or forming a pillow-type packaging bag into a cylindrical shape. Furthermore, the time for which the sealing surface 12 holds the packaging material, the temperature of the heat source 13, the opening and closing speed of the arm 14, and the pressure at which the arm 14 presses the heat bars 11, 11 against each other are controlled by the heat sealing device 10 or a control unit (not shown) provided in the packaging machine into which the heat sealing device 10 is incorporated. As a result, the heat sealing device 10 can weld the overlapping portions of the packaging material by having heat bars 11, 11, provided at the tips of arms 14 that open and close at predetermined timings, heat-controlled sealing surfaces 12 that are heated to a predetermined temperature range where the overlapping portions of the packaging material are welded together, and clamping the packaging material with a predetermined pressure for a predetermined time.

[0020] As shown in Figures 2 to 4, the heat bar 11 is composed of a heat bar body 20 made of a columnar metal member and a faceted portion 21. The heat bar body 20 has a smooth adhesive surface 22 on the front surface where the heat bars 11 face each other. Hereinafter, the adhesive surface 22 of the heat bar body 20 will be referred to as the front side, and the direction from the adhesive surface 22 toward the back side will be referred to as the thickness direction of the heat bar body 20. As shown in Figures 2 to 4, the faceplate portion 21 is bonded and fixed to the front surface of the adhesive surface 22 via a heat-resistant adhesive (not shown). As shown in Figure 2, the heat bar body 20 has through holes 15 formed along its longitudinal direction at predetermined positions along its thickness and height. A heat source 13 having a cartridge heater with a cylindrical heating element is fitted into these through holes 15. The heat source 13 is pressed toward the front side of the heat bar body 20, toward the adhesive surface 22, by retaining bolts (not shown) that are screwed into threaded holes 16 formed from the back side of the heat bar body 20 toward the through holes 15. In this embodiment, the heat bar body 20 is preferably made of iron, but is not limited to iron; for example, a metal with high thermal conductivity such as copper can be appropriately selected. Furthermore, as shown in Figure 1, the structure is not limited to fixing the facepiece portion 21 to both heat bars 11, 11. One of the heat bars 11 may be configured to have the facepiece portion 21 according to this embodiment, while the other heat bar 11 may be a heat bar with a sealing surface having grooves or the like formed on it, similar to conventional heat bars. Moreover, one of the heat bars 11 may be configured to have the facepiece portion 21 and heat source 13 according to this embodiment, while the other may not have a heat source 13, or a cooling device may be fitted into the through hole 15, so that one is a heat bar 11 that heats, and the other is a heat dissipation bar that can dissipate or cool heat from the sealing surface in contact with the packaging material. Furthermore, a small-diameter through-hole 17 communicating with the through-hole 15 is fitted with a temperature sensor, preferably a thermocouple. This allows for the detection of heat conducted from the heat source 13 to the heat bar body. The heat detected by the temperature sensor is converted into a thermal signal and transmitted to the control unit. The control unit is configured to control the temperature of the heat bar body based on the fed-back thermal signal. In this embodiment, the heat bar 11 has a heat bar body 20 having the above configuration, and a facet portion 21 that can be deformed in response to an applied external force is fixed to the first adhesive surface 22 in a predetermined position.

[0021] As shown in Figures 2 to 4, the facepiece portion 21 is composed of a high thermal conductivity rubber material 23 formed in the form of a sheet of a predetermined thickness, a carbon graphite sheet 24 placed on the adhesive surface 22 side of the high thermal conductivity rubber material 23, and a high heat-resistant sheet 25 placed on the sealing surface 12 side of the high thermal conductivity rubber material 23. The high thermal conductivity rubber material 23 has a thickness of 0.5 mm to 3.0 mm, preferably 1.0 mm. The thickness of the high thermal conductivity rubber material 23 is not limited to the thickness of this embodiment and can be selected as appropriate. However, if the high thermal conductivity rubber material 23 is 0.5 mm thick or less, when heat sealing is performed, it becomes extremely difficult to apply uniform pressure to the surface to be sealed on the packaging material side by absorbing the irregularities that occur on the surface to be sealed, which may lead to poor welding. On the other hand, if the high thermal conductivity rubber material 23 is 3.0 mm thick or more, the elasticity and flexibility of the rubber material become excessive, and when heat sealing is performed, the high thermal conductivity rubber material 23 may be greatly crushed and distorted. If this is repeated, the durability of the high thermal conductivity rubber material 23 may deteriorate significantly. Furthermore, if the thickness of the high thermal conductivity rubber material 23 becomes 3.0 mm or more, the distance between the sealing surface 12 sandwiching the facepiece 21 and the heat source 13 increases. Due to the high thermal conductivity of the high thermal conductivity rubber material 23 itself, heat may be dissipated before it can be conducted to the sealing surface 12, potentially causing the sealing surface 12 to cool down. As a result, it may become impossible to maintain the proper sealing temperature of the sealing surface 12 when performing heat sealing. Furthermore, the high thermal conductivity rubber material 23 has a thermal conductivity of 5 W / mK to 40 W / mK. Although this thermal conductivity is not as high as that of metals such as copper or iron or carbon graphite sheets, when heated from the adhesive surface 22 side, heat is uniformly conducted toward the sealing surface 12 side. As a result, the heat applied to the high thermal conductivity rubber material 23 diffuses evenly as it conducts through the material, allowing the entire sealing surface 12 to be heated evenly. Alternatively, a temperature sensor consisting of a thermocouple may be sandwiched between the facepiece 21 and the heat bar body 20. This allows for the detection of heat conducted from the heat bar body 20 to the facepiece 21 and further to the sealing surface 12. The heat detected by the temperature sensor is converted into a thermal signal and transmitted to the control unit. Based on the fed-back thermal signal, the control unit can further precisely control the temperature of the heat bar body 20 in conjunction with the detection result of the temperature sensor installed on the heat bar body 20.

[0022] As shown in Figure 2 or Figure 3, the carbon graphite sheet 24 is sandwiched between the high thermal conductivity rubber material 23 and the heat bar body 20. By interposing the carbon graphite sheet 24, rather than directly bonding the high thermal conductivity rubber material to the bonding surface 22, the high thermal conductivity rubber material 23 and the carbon graphite sheet 24, and the carbon graphite sheet 24 and the metal heat bar body 20 can be firmly bonded, improving durability when heat sealing is repeated. Furthermore, since the carbon graphite sheet 24 has superior thermal conductivity along the plane direction compared to the high thermal conductivity rubber material 23, it can quickly diffuse the heat conducted from the heat source 13 to the adhesive surface 22 onto the adhesive surface 22 and then conduct it to the high thermal conductivity rubber material 23. By quickly diffusing the heat along the plane direction, it can then be heated uniformly in the thickness direction, resulting in a uniform temperature distribution on the sealing surface 12.

[0023] As shown in Figures 2 to 4, the high heat-resistant sheet 25 is attached to the sealing surface 12 side of the high thermal conductivity rubber material 23. Preferably, the high heat-resistant sheet 25 has excellent release properties. This allows the sealing surface 12 to be quickly separated from the sealing surface by reducing its adhesion to the sealing surface compared to the high thermal conductivity rubber material 23 when the sealing surface of the packaging material is heat-sealed. Alternatively, the high heat-resistant sheet 25 may be replaced with a high heat-resistant coating material. Preferably, the high heat-resistant sheet 25 or high heat-resistant coating material is a non-fluorine-based heat-resistant synthetic resin. This reduces the environmental impact of the facepiece 21. On the other hand, if the sealing surface 12 provided on the high thermal conductivity rubber material 23, whose viscosity and hardness are appropriately adjusted, has sufficient elasticity and release properties relative to the packaging material, the high heat-resistant sheet 25 or high heat-resistant coating material can be omitted. Furthermore, the high heat-resistant sheet 25 or high heat-resistant coating material is not limited to heat-resistant synthetic resins; for example, a ceramic sheet or coating material composed of carbon graphite, alumina, zirconia, silicon nitride, or other ceramic materials may be used. These ceramic sheet materials and coating materials, like heat-resistant synthetic resins, also possess appropriate flexibility while exhibiting excellent heat resistance and release properties. Therefore, when heat-sealing the packaging material, the sealed surface of the packaging material can be sealed without hindering the movement of the heat bar 11.

[0024] The operation of the heat bar having the above configuration will be explained with reference to the attached drawings. The heat bar according to this embodiment constitutes a heat sealing device 10, as shown in Figure 1. The heat sealing device 10 forms a packaging bag called a gusset bag or stand-up pouch, and seals the opening of such packaging bags. Here, a gusseted bag refers to a packaging bag B in which, as shown in Figure 5, the side edges of the packaging bag B are folded inward to form a sleeve gusset 1. When the packaging bag B is folded, the sleeve gusset 1 portion is where the packaging material overlaps in four layers, as shown in Figure 6, and is referred to as the four-layer portion Q. On the other hand, the portion that does not overlap with the sleeve gusset 1 consists of two layers of packaging material, and is referred to as the two-layer portion W. The sleeve gusset 1 portion of the four-layer portion Q is thicker than that of the two-layer portion W due to the thickness of the packaging material. Although not shown in the diagram, a stand-up pouch is a type of packaging bag in which the bottom of the bag is folded inward to form a gusset, allowing it to stand on its own. Like a gusseted bag, this stand-up pouch also has a gusseted bottom section where the packaging material overlaps in four layers, and a section other than the gusseted bottom section where the packaging material overlaps in two layers. In this embodiment, as shown in Figures 5 to 7, packaging bag B, which is a gusseted bag, will be used as an example for the following explanation.

[0025] As shown in Figure 6, the cross-sectional shape of the above-mentioned packaging bag B in plan view consists of a four-layer section Q into which the sleeve gusset 1 is folded, and a two-layer section W that does not overlap with the sleeve gusset 1. Depending on the film thickness of the packaging material that makes up packaging bag B, the thickness of the four-layer section Q is 400 μm to 1.0 mm, and the thickness of the two-layer section W is 200 μm to 0.5 mm. Therefore, the difference between the four-layer section Q and the two-layer section W is the thickness of two layers of packaging material, which is 200 μm to 0.5 mm. If this packaging material is crushed as is with a conventional heat bar that has a hard, smooth surface, the difference between the four-layer section Q and the two-layer section W will appear as a step, which may cause poor welding.

[0026] When packaging bag B is heat-sealed, as shown in Figure 1, the facepieces 21 of the opposing heat bar bodies 20 press down on the sealing surfaces 12 from both sides of packaging bag B against the surface to be sealed. At this time, as shown in Figure 7, the portion of the sealing surface 12 facing the four-layer portion Q first comes into contact, and the high-conductivity rubber material 23 of the facepiece 21 is crushed. Furthermore, when pressure is applied to the surface to be sealed of packaging bag B, the portion of the sealing surface 12 facing the two-layer portion W comes into contact, and the entire sealing surface 12 presses against the four-layer portion Q and the two-layer portion W, and the high-thermal-conductivity rubber material 23 constituting the facepiece 21 is crushed overall. As a result, the high-thermal-conductivity rubber material 23 of the facepiece 21 is crushed against the surface to be sealed of packaging bag B, and the pressure applied by the sealing surface 12 to the surface to be sealed is equalized. In addition, the heat conducted from the heat bar body 20 to the high-thermal-conductivity rubber material 23 is uniformly conducted from the sealing surface 12 to the surface to be sealed. Thus, the sleeve gusset 1 provides a four-layer section Q and a two-layer section W, and as shown in Figure 7, the sealing surface 12 can be heat-sealed with uniform pressure on the sealing surface where a step 2 is created, thereby preventing welding defects. Furthermore, since the sealing surface can be welded in a single heat-sealing process, the thermal history of the packaging material is reduced, and a high-quality heat seal can be achieved.

[0027] After heat sealing, when the heat bars 11, 11 separate in opposite directions, the seal surface 12 quickly separates from the surface to be sealed due to the excellent release properties of the high heat-resistant sheet 25 attached to the surface of the high heat-conducting rubber material 23, and the high heat-conducting rubber material 23 instantly recovers as the pressure is released. As a result, when the next packaging bag B to be heat-sealed is placed between the heat bars 11, 11, the predetermined parts of the sealing surface 12 are indented sequentially from the four-layer section Q to the two-layer section W, as described above, thereby absorbing the step difference 2.

[0028] According to the heat bar 11 of this embodiment, during heat sealing, the highly thermally conductive rubber material 23 of the facepiece 21 is compressed, causing the sealing surface 12 to flex and conform to the step 2 that occurs at the boundary between the four-layer portion Q and the two-layer portion W of the surface to be sealed, as well as the irregularities that occur on the surface to be sealed. As a result, even with packaging bags using packaging materials that are highly reactive and sensitive to sealing temperature, the heat history is reduced and the sealing quality is improved. Therefore, the step 2 that occurs on the surface to be sealed of the packaging material constituting the gusset bag or stand-up pouch can be easily absorbed, and sealing heat can be applied uniformly to the surface to be sealed of the packaging material, enabling high-quality heat sealing with a low heat history in a single sealing operation. [Example 2]

[0029] Other embodiments of the heat bar according to the present invention will be described with reference to the attached drawings. Figure 8 or 9 is an explanatory diagram showing a schematic configuration of the heat bar according to this embodiment.

[0030] The heat sealing device 10 has the same configuration as the first embodiment, so its description will be omitted. The heat sealing device 10 has a pair of heat bars 11A, 11A facing each other, and each heat bar 11A is composed of a heat bar body 20A and a face portion 21A.

[0031] As shown in Figure 8, the heat bar body 20A has a cross-sectional shape along its thickness that is roughly U-shaped, and has a facet housing portion 30 surrounded by an upper side surface 30a, a lower side surface 30b, and a recessed bottom surface 30c. An upper engaging portion 31, folded back in a roughly G-shape, is connected to the front side of the upper side surface 30a, and a lower engaging portion 32, folded back in a roughly L-shape, is connected to the front side of the lower side surface 30b. As shown in Figure 8 or Figure 9, the heat bar body 20A has a through hole 15 formed along its longitudinal direction at a predetermined position on the inner side of the recess bottom surface 30c. A heat source 13 having a cartridge heater with a cylindrical heating element is fitted into the through hole 15. The heat source 13 is pressed toward the recess bottom surface 30a by a retaining bolt (not shown) that is screwed into a screw hole 16 formed from the back side of the heat bar body 20A toward the through hole 15. In this embodiment, the heat bar body 20A is preferably made of iron, but is not limited to iron; for example, a metal with high thermal conductivity such as copper can be appropriately selected. Furthermore, as shown in Figure 1, the structure is not limited to one in which both heat bars 11A are equipped with the heat bar body 20A according to this embodiment. One of the heat bars 11A may be the heat bar 11A according to this embodiment, and the other heat bar 11A may be the same as a conventional heat bar. Moreover, one of the heat bars 11A may be the heat bar according to this embodiment, and the other may not have a heat source 13, or a cooling device may be fitted into the through hole 15, so that one heat bar 11A is equipped with the heat source according to this embodiment, and the other is configured as a heat dissipation bar that can dissipate or cool heat from the sealing surface in contact with the packaging material. Furthermore, a small-diameter through-hole 17 communicating with the through-hole 15 is fitted with a temperature sensor, preferably a thermocouple. This allows for the detection of heat conducted from the heat source 13 to the heat bar body 20A. The heat detected by the temperature sensor is converted into a thermal signal and transmitted to the control unit. The control unit is configured to control the temperature of the heat bar body 20A based on the feedback thermal signal.

[0032] As shown in Figure 8 or Figure 9, the facepiece portion 21A is composed of a stacked pillar 35 and a cushioning material 36. The integrated pillar 35 is composed of multiple stacked convex-shaped metal sheets 35a and a tape (not shown) connecting the metal sheets. The thin metal sheet 35a is preferably made of iron or copper, but is not limited to these; any metal with high thermal conductivity is acceptable. The thickness of the thin metal sheet is 0.1 mm to 1.0 mm, preferably 0.4 mm. If the thickness of the metal sheet 35a is 0.1 mm or less, the strength of the metal sheet 35a cannot be maintained. Therefore, the metal sheet 35a may bend due to the pressure applied to the sealing surface 12A. If the metal sheet 35a bends significantly, it may not be possible to apply appropriate pressure to the packaging material and the sealing surface 12A may not be properly maintained, which may cause problems with the durability of the heat bar 11A. On the other hand, if the thickness of the thin metal sheet 35a is 1.0 mm or more, it may not be possible to follow the irregularities that occur on the surface to be sealed, as described later, and there is a risk of poor welding due to a step formed at the boundary between the four-layer section Q and the two-layer section W, or due to excessive or insufficient pressure on the four-layer section Q or the two-layer section W. The thin metal sheet 35a has a slit-shaped tape slit 35b near the center of its convex shape. By inserting tape through the tape slit 35b, the thin metal sheets 35a are connected to form an integrated pillar 35. The tape is a metal tape made of iron or the like, but is not limited to such a metal tape. It may also be a tape made of a non-ferrous metal, carbon fiber, or ceramic fiber having flexibility and strength comparable to that of the metal tape. The tape is inserted through a tape slit 35b of a thin metal plate 35a, and multiple thin metal plates 35a are connected so that their surfaces are in contact with each other and they can slide against each other. The integrated pillar 35 has a convex shape in cross-sectional view along its thickness direction, as shown in Figure 8, which corresponds to the shape of the thin metal sheet 35a. A sealing surface 12A is formed on the tip surface of the convex portion, and an upper shoulder portion 37a is formed above the sealing surface 12A along the thickness direction, while a lower shoulder portion 37b is formed below it. The upper shoulder portion 37a faces the upper engaging portion 31 of the heat bar body 20A, and the lower shoulder portion 37b faces the lower engaging portion 32 of the heat bar body 20A. Thus, in the integrated pillar 35, the thin metal sheets 35a are connected so as to be slidable along the thickness direction, while their movement along the longitudinal or height direction is restricted by the tape connecting the thin metal sheets 35a. In other words, the integrated pillar 35 is composed of multiple thin metal sheets 35a whose movement is restricted along the thickness direction. This allows the portion of the thin metal sheet 35a to which the external force is applied to slide toward the back along the thickness direction when an external force is applied to the sealing surface 12A.

[0033] As shown in Figure 8, the cushioning material 36 is positioned between the recessed bottom surface 30c and the integrated pillar 35 within the facet housing portion 30 of the heat bar body 20A, and is fixed to the recessed bottom surface 30c of the heat bar body 20A. The cushioning material 36 is preferably a heat-resistant rubber material with flexibility and elasticity, but a synthetic resin material with heat resistance and flexibility may also be used. The thickness of the heat-resistant rubber material is 1.0 mm to 5.0 mm, preferably 2.0 mm. If the thickness of the heat-resistant rubber material is 1.0 mm or less, as described later, the sinking of the metal sheet 35a cannot be tolerated, and depending on the film thickness of the packaging material to be heat-sealed, it may not be possible to absorb the difference in thickness and step between the four-layer section Q and the two-layer section W. This may result in poor sealing of the packaging bag B. On the other hand, if the thickness of the heat-resistant rubber material is 5.0 mm or more, the sufficiently sunk metal sheet 35a may instead bite into the heat-resistant rubber material, which may delay recovery after heat sealing.

[0034] As shown in Figure 8 or Figure 9, the heat bar 11A is constructed by housing an integrated pillar 35, which is made by connecting multiple thin metal plates 35a through tape slits 35b of the thin metal plates 35a using tape, into the facepiece housing 30 of the heat bar body 20A so that it protrudes toward the opening end of the facepiece housing 30, that is, toward the front of the heat bar 11A. As a result, the heat bar body 20A is housed in the facepiece housing 30 so as to surround the facepiece 21A, and the sealing surface 12A of the integrated pillar 35 is exposed from the opening end of the facepiece housing 30. The upper shoulder portion 37a of the integrated pillar 35 engages with the upper engaging portion 31 of the heat bar body 20A, and the lower shoulder portion 37b engages with the lower engaging portion 32 of the heat bar body 20A. This prevents the integrated pillar 35, which is housed in the facet housing portion 30 of the heat bar body 20A, from coming loose from the body housing portion 30. The integrated pillar 35 is in slidable contact with the lower surface 30b of the facepiece housing 30 due to its own weight. On the other hand, the upper surface of the integrated pillar 35 is in close proximity to the facepiece housing 30, leaving a minute gap between them. This restricts vertical displacement of the thin metal plate 35a constituting the integrated pillar 35, and allows heat to be conducted from the heat bar body 20A, which is controlled to a predetermined temperature, to the integrated pillar 35. Furthermore, the heat bar 11A is not limited to the configuration of the heat bar body 20A and facet portion 21A shown in this embodiment, and is not limited to a convex shape. It can be configured by stacking multiple thin metal sheets or high thermal conductivity plate materials having a similar composition to the thin metal sheets to form an integrated pillar, which is connected so that the thin metal sheets or high thermal conductivity plate materials do not fall out, and fixed to the heat bar body 20A via a buffer material 36.

[0035] The operation of the heat bar 11A configured as described above will be explained with reference to the attached drawings. The packaging bag B to be heat-sealed is a gusseted bag as shown in Figure 5, as in the first embodiment, and the configuration of the gusseted bag will not be explained.

[0036] When packaging bag B is heat-sealed, as shown in Figure 10, the facepieces 21A of the opposing heat bar bodies 20A press down on the sealing surface 12 from both sides. At this time, the side edge of the metal sheet 35a facing the four-layer section Q first comes into contact with the sealing surface 12 and slides along the thickness direction of the facepiece 21A, causing the side edge of the metal sheet 35a on the side opposite the four-layer section Q to press in the cushioning material 36. Furthermore, when pressure is applied to the sealing surface, the side edge of the metal sheet 35a of the sealing surface 12 facing the two-layer section W comes into contact with it, and the entire sealing surface 12 of the stacked pillar 35 presses against the four-layer section Q and the two-layer section W, and on the opposite side of the sealing surface 12, the cushioning material 36 is crushed. As a result, the faceplate portion 21A can apply uniform pressure to the surface to be sealed by the thin metal plates 35a that constitute the integrated pillars 35. In addition, the heat conducted from the heat bar body 20A to the integrated pillars 35 is uniformly applied to the surface to be sealed from the sealing surface 12. Thus, the sleeve gusset 1 provides a four-layer section Q and a two-layer section W, and as shown in Figure 10, the sealing surface 12 can be heat-sealed with uniform pressure on the sealing surface where a step 2 is created, thereby preventing welding defects. Furthermore, since the sealing surface can be welded in a single heat-sealing process, the thermal history of the packaging material is reduced, and a high-quality heat seal can be achieved.

[0037] After heat sealing, when the heat bars 11A, 11A move apart in opposite directions, the sealing surface 12 separates from the surface to be sealed, and the facepiece 21A instantly returns to its initial position as the pressure applied to the cushioning material 36 is released. As a result, when the next packaging bag B to be heat-sealed is placed between the heat bars 11A, 11A, the predetermined parts of the sealing surface 12 are indented sequentially from the four-layer section Q to the two-layer section W, as described above, thereby absorbing the step difference 2.

[0038] According to the heat bar 11A of this embodiment, the cushioning material 36 provided in the facepiece portion 21A is compressed during heat sealing, and the sealing surface 12 formed by the metal plate 35a that can slide along the thickness direction follows the step 2 that occurs at the boundary between the four-layer portion Q and the two-layer portion W of the surface to be sealed, as well as the irregularities that occur on the surface to be sealed. As a result, even with packaging bags using packaging materials that are highly reactive and sensitive to sealing temperature, the heat history is reduced and the sealing quality is improved. Therefore, the step that occurs on the surface to be sealed of the packaging material constituting the gusset bag or stand-up pouch can be easily absorbed, and sealing heat can be applied uniformly to the surface to be sealed of the packaging material, enabling high-quality heat sealing with a low heat history in a single sealing operation. [Example 3]

[0039] Other embodiments of the heat bar according to the present invention will be described with reference to the attached drawings. Figure 11 or Figure 12 is an explanatory diagram showing a schematic configuration of the heat bar according to this embodiment.

[0040] The heat sealing device 10 has the same configuration as in the first and second embodiments, so its description will be omitted. The heat sealing device 10 has a pair of heat bars 11B, 11B facing each other, and each heat bar 11B is composed of a heat bar body 20 and a face portion 21B. Here, the heat bar body 20 has the same configuration as in the first embodiment, so its description is omitted.

[0041] As shown in Figure 8, the facepiece portion 21B is equipped with a sealing surface 12 and is composed of a surface film 40, a core material 41, and a filler material 42, as shown in Figure 9. The surface film 40 is made of a metal foil having predetermined elasticity and strength. A sealing surface 12 is formed on the surface of the surface film 40, as shown in Figure 8. The surface film 40 is preferably made of a metal foil such as iron, aluminum, or copper, but is not limited to this, and a non-metallic material with high thermal conductivity, such as a carbon graphite sheet formed in a thin film or a ceramic sheet, may also be used.

[0042] The core material 41 is formed by folding a metal foil having predetermined elasticity and strength, similar to the surface film 40, multiple times to approximately the same width, so that when viewed from above, multiple equilateral triangles or isosceles triangles of predetermined angles are connected, as shown in Figure 9. Note that the core material 41 in this embodiment is not limited to a structure formed by folding a metal foil to create a series of triangles, as shown in Figure 9; the metal foil may also be formed by curving it into a corrugated shape. The surface film 40 is then bonded to one side of the core material 41, as shown in Figure 9. While the core material 41 is preferably a metal foil having predetermined strength, similar to the surface film 40, it is not limited to this; non-metallic materials with high thermal conductivity, such as a thin-film carbon graphite sheet or a ceramic sheet, may also be used.

[0043] In this embodiment, it is preferable that the metal foil constituting the surface film 40 and the core material 41 are both thin film members with a thickness of 0.1 mm or less. The other side of the core material 41, to which the surface film 40 is bonded, is bonded to the adhesive surface 22 of the heat bar body 20, as shown in Figure 9. As a result, when viewed in cross-section along the thickness direction from the facet portion 21B composed of the surface film 40 and the core material 41 and the adhesive surface 22 of the heat bar body 20, a truss structure is formed on the adhesive surface 22 side of the heat bar body 20, as shown in Figure 9. Thus, the facet portion 21B with the truss structure has predetermined elasticity along the longitudinal and thickness directions and predetermined rigidity along the height direction. Therefore, the sealing surface formed on the surface of the facet portion 21B can flexibly follow the irregularities in the longitudinal direction of the surface to be sealed of the packaging material and absorb irregularities and steps along the thickness direction. On the other hand, since it has predetermined strength along the height direction relative to the surface to be sealed, the heat bar 11B can be made durable.

[0044] The filler 42 fills the triangular gap formed between the surface film 40 and the core material 41, and the roughly triangular gap formed between the core material 41 and the adhesive surface 22. As described above, the surface film 40 and the core material 41 are formed from thin film members such as metal foil, so if the gaps are left as spaces that communicate with the outside air, there is a risk that the entire sheet surface 12 will collapse when pressure is applied with an external force. Therefore, the filler 42 is made of a flexible synthetic resin material, such as silicone resin, that gives the truss structure a predetermined strength. Furthermore, the filler 42 is not limited to a flexible synthetic resin material. Instead of the synthetic resin material, for example, fine powdered metal powder or carbon powder may be used to ensure a predetermined strength and high thermal conductivity. Alternatively, the filler 42 may be a liquid such as oil or water with a predetermined viscosity, or a semi-solid gel, for example, by adding additives. In this case, even if the oil or the like has thermal insulation properties, heat can be conducted from the heat bar body 20 to the sealing surface 12 of the surface film 40 via the core material 41, since the adhesive surface 22 of the heat bar body 20 and the core material 41, and the core material 41 and the surface film 42 are in contact. By filling the roughly triangular gaps in the truss structure with the above-mentioned filler material 42 and sealing them, the facepiece portion 21B can be given a predetermined degree of flexibility and elasticity. Furthermore, in this embodiment, a configuration in which a facet portion 21B consisting of a surface film 40 and a core material 41 is bonded to the adhesive surface 22 is illustrated, but the invention is not limited to this. Alternatively, a backing film may be bonded to the opposite side of the surface film 40 with the core material 41 in between, and a facet portion 21B may be constructed by filling and sealing the gaps of the similarly formed truss structure with a filler material 42, and then bonding and fixing it to a predetermined position on the adhesive surface 22.

[0045] The operation of the heat bar 11B configured as described above will be explained with reference to the attached drawings. The packaging bag B to be heat-sealed is a gusseted bag as shown in Figure 5, as in the first and second embodiments, and the configuration of the gusseted bag will not be explained.

[0046] When the packaging bag B is heat-sealed, as shown in Figure 13, the facepieces 21B of the opposing heat bar bodies 20 press down on the opposing sealing surfaces 12 from both sides against the surface to be sealed. At this time, the portion of the sealing surface 12 facing the four-layer portion Q first comes into contact, causing the surface film 40 to bend along the thickness direction of the facepiece 21B, and the core material 41 and filler material 42 to be crushed. Furthermore, when pressure is applied to the surface to be sealed, the portion of the sealing surface 12 facing the two-layer portion W comes into contact, and the entire sealing surface 12 of the facepiece 21B presses against the four-layer portion Q and the two-layer portion W, crushing the core material 41 and filler material 42. As a result, the facepiece portion 21B can apply uniform pressure to the surface to be sealed by the filler material 42 partitioned within the core material 41. In addition, the heat conducted from the heat bar body 20 through the core material 41 to the surface film 40 is uniformly applied to the surface to be sealed from the sealing surface 12. Thus, the sleeve gusset 1 provides a four-layer section Q and a two-layer section W, and as shown in Figure 13, the sealing surface 12 can be heat-sealed with uniform pressure on the sealing surface where a step 2 is created, thereby preventing welding defects. Furthermore, since the sealing surface can be welded in a single heat-sealing process, the thermal history of the packaging material is reduced, and a high-quality heat seal can be achieved.

[0047] After heat sealing, when the heat bars 11B, 11B move apart in opposite directions, the sealing surface 12 separates from the surface to be sealed, and the facepiece 21B instantly returns to its initial position as the pressure applied to the core material 41 and filler material 42 is released. As a result, when the next packaging bag B to be heat-sealed is placed between the heat bars 11B, 11B, the predetermined parts of the sealing surface 12 are indented sequentially from the four-layer section Q to the two-layer section W, as described above, thereby absorbing the step difference 2.

[0048] In this embodiment, the heat bar 11B is used to compress the core material 41 and filler 42 of the facepiece 21B during heat sealing. The sealing surface 12 formed by the surface film 40 adhered to the core material 41 conforms to the step 2 that occurs at the boundary between the four-layer portion Q and the two-layer portion W of the surface to be sealed, as well as the irregularities that occur on the surface to be sealed. This makes it possible to improve the sealing quality by reducing the thermal history, even for packaging bags B that use packaging materials that are highly reactive and sensitive to sealing temperature. As a result, it is possible to easily absorb the step that occurs on the surface to be sealed of the packaging material constituting the gusset bag or stand-up pouch, apply sealing heat uniformly to the surface to be sealed of the packaging material, and perform high-quality heat sealing with a low thermal history in a single sealing operation.

[0049] According to the heat bars 11, 11A, and 11B of the first to third embodiments, the heat bars 11, 11A, and 11B are composed of a heat bar body 20, 20A and a facepiece portion 21, 21A, and 21B which are attached to the adhesive surface 22 side of the heat bar body 20, 20A and have a sealing surface 12 formed to deform in response to the applied external force. As a result, when the sealing surface 12 is brought into contact with the surface to be sealed of the packaging bag B and a predetermined pressure is applied to press the sealing surface 12 against the surface to be sealed, the sealing surface 12 deforms in response to the external force received from the surface to be sealed, following the irregularities present on the surface to be sealed. Therefore, a gusset bag or stand-up pouch with a step 2 at the boundary between the four-layer portion Q and the two-layer portion W can be heat-sealed in a single operation. In this way, since the gusset bag or stand-up pouch with the step 2 can be welded in a single heat seal, the heat sealing device 10 can reduce the thermal history in a series of heat sealing processes in which it heat seals the surface of the packaging bag B, thereby preventing the physical embrittlement of the synthetic resin material used in the packaging material constituting the packaging bag B due to heating, and enabling the manufacture of high-quality packaging products. [Explanation of Symbols]

[0050] 10... Heat sealing device, 11, 11A, 11B... Heat bar, 12... Sealing surface, 13... Heat source, 14... Arm, 15... Through hole, 16... Screw hole, 17... Small diameter through hole, 20,20A...heat bar body, 21,21A,21B...facepiece part, 22...adhesive surface, 23... High thermal conductivity rubber material, 24... Carbon graphite sheet, 25... High heat resistant sheet, 30...facepiece housing section, 30a...upper side surface, 30b...lower side surface, 30c...bottom surface of recess, 31...upper engaging section, 32...lower engaging section, 35... Integrated pillar, 35a... Thin metal sheet, 35b... Tape slit, 36... Cushioning material, 37a... Upper shoulder part, 37b... Lower shoulder part, 40...Surface film, 41...Core material, 42...Filling material, B...Packaging bag, 1...Sleeve gusset, 2...Step, Q...4th layer part, W...2nd layer part.

Claims

1. A heat bar provided in a heat sealing device, The heat bar comprises a faceplate with a sealing surface that deforms in response to an applied external force, It consists of a heat bar body to which the facepiece is fixed, When the sealing surface of the facepiece is pressed against the surface of the packaging material to be sealed, A heat bar characterized in that the sealing surface deforms to conform to irregularities that occur on the surface to be sealed.

2. The heat bar according to claim 1, characterized in that the facet portion is made of a highly thermally conductive rubber material formed in a sheet of a predetermined thickness.

3. The aforementioned facet portion is formed in a prismatic shape by accumulating multiple members whose movement direction is restricted to the thickness direction, and is an accumulated pillar with a sealing surface on its front, A cushioning material is placed between the back of the integrated pillar and the heat bar body, The heat bar according to claim 1, characterized in that it is composed of the following.

4. The integrated pillar is formed by stacking multiple convex-shaped thin metal plates and arranging them so that they are convex toward the front, The heat bar body is formed to surround the aforementioned integrated pillar, and has a cross-sectional shape in the thickness direction that is substantially U-shaped. The heat bar according to claim 3, characterized in that the sealing surface formed on the convex portion of the integrated pillar is exposed from an open end formed on the front surface of the heat bar body.

5. The heat bar according to claim 3, characterized in that the cushioning material is made of rubber.

6. The heat bar according to claim 3, characterized in that the cushioning material is a flexible synthetic resin material.

7. The facepiece portion comprises a surface film having a sealing surface, It consists of a core material made of foil material that has been folded multiple times at a predetermined angle, The back surface of the core material is placed in front of the heat bar body, and the surface film is placed on the front side of the core material. When viewed in cross-section along the thickness direction of the aforementioned facet, a truss structure is formed in which gaps divided into approximately triangular sections are continuously arranged. The heat bar according to claim 1, characterized in that a flexible filler is sealed in the gap.

8. The heat bar according to claim 7, characterized in that the surface film and the core material are made of metal foil.

9. The heat bar according to claim 7, characterized in that the surface film and the core material are made of a carbon graphite sheet.

10. The heat bar according to claim 7, characterized in that the filler is a synthetic resin material.

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