JP7568218B2 - Sealing member and heat sealing device using same - Google Patents

Description

This invention relates to a sealing member and a heat sealing device using the same.

Bag making machines for manufacturing various types of bags are equipped with a heat sealing device that heat seals (thermally fuses) multiple films that will be used to make the bags together. The heat sealing device has a pair of upper and lower sealing bodies arranged opposite each other, and the multiple films that will be used to make the bags are sandwiched between the abutting surfaces of these sealing bodies, and heat and pressure are applied to the films to perform the heat seal.

To ensure the desired quality (seal strength) in heat sealing, it is important to control the temperature, pressure and time during sealing. The pressure in particular can fluctuate due to wear and deformation over time of the sealing body and the parts that drive the sealing body, so it is advisable to observe and adjust as appropriate.

One method for detecting the pressure during sealing is to detect the pressure of the cylinder that drives the sealing body (see, for example, the following patent document). However, with this method, it is difficult to confirm and evaluate the pressure acting on the area within the contact surface of the sealing body where the film is actually pressed, or the pressure distribution within the contact surface.

JP 2014-172654 A

In light of the above circumstances, the present invention aims to provide a sealing member that can detect the pressure acting on a specific area within the contact surface where the film is pressed or directly below the contact surface, and a heat sealing device that uses the same.

The sealing member of the present invention is a sealing member that presses together a plurality of films in cooperation with a mating member,
a contact surface that contacts the film;
a pressure sensor having a pressure receiving portion provided at a position overlapping with the contact surface when projected and observed in a direction perpendicular to the contact surface;
and a base body for supporting the pressure sensor.
According to the present invention, when multiple films are pressed together in cooperation with a mating member, the pressure acting on a specified area within the contact surface or immediately below the contact surface where the films are actually pressed can be detected, and the sealing conditions can be confirmed and evaluated based on the obtained pressure signal.

The present invention can further include a waveform acquisition means for acquiring a waveform representing the change in pressure over time based on the pressure signal from the pressure sensor. In this way, the sealing conditions can be confirmed and evaluated based on the shape of the pressure waveform that changes over time.

In addition, in the present invention, a sheet-shaped insulating layer can be provided between the contact surface and the pressure sensor. This prevents the pressure sensor from being exposed to high temperatures due to heat from a heater embedded in the mating member, and prevents the pressure signal output from the pressure sensor from fluctuating due to the influence of the heat from the heater.

In addition, in the present invention, the base body can be a heater unit including a heater for heating. By making the base body adjacent to the pressure sensor into a heater unit in this way, the temperature of the pressure sensor can be controlled within a predetermined temperature range above room temperature, and the variation in the pressure signal caused by temperature changes in the pressure sensor can be suppressed.

In addition, in the present invention, by disposing a shim plate between the contact surface and the base body in an area where the pressure sensor is not disposed, the pressure distribution on the contact surface when the film is pressed can be adjusted. In this way, it is possible to prevent localized increases in pressure in the area of the contact surface that overlaps with the pressure sensor due to the placement of the pressure sensor.

In addition, in the present invention, an elastically deformable sheet-like elastic layer can be provided between the contact surface and the pressure sensor. By providing an elastic layer between the contact surface and the pressure sensor in this way, it is possible to achieve a uniform pressure distribution within the contact surface, more specifically, in the pressure bonding area where the film is bonded in cooperation with the opposing member, when the film is bonded.

In addition, in the present invention, one or more pressure sensors can be provided.

The present invention also has an attachment portion and can be configured to be attachable to a heat sealing device via the attachment portion. In this way, it can be easily retrofitted to an existing heat sealing device.

The heat sealing device of the present invention is a heat sealing device that comprises a first sealing body and a second sealing body arranged opposite the first sealing body, and that sandwiches multiple films between the pair of sealing bodies and applies heat and pressure to the films to heat seal them, and is characterized in that the first sealing body or the second sealing body is composed of the sealing member of the present invention described above.
According to the heat sealing device of the present invention, for each sealing operation in which multiple films are pressed together, the pressure acting on a specified area within the contact surface of the sealing body where the films are pressed or immediately below the contact surface can be detected and output, and the sealing conditions can be confirmed and evaluated based on the output signal related to the obtained pressure.

Here, in the heat sealing device of the present invention, the pressure receiving portion of the pressure sensor can be disposed at a position where the line of action of the pressing force acting on either the first or second sealing body through the other sealing body passes. In this way, pressure adjustment can be easily performed based on the signal output from the pressure sensor.

FIG. 2 is a perspective view of a main body of a sealing member according to one embodiment of the present invention. FIG. 2 is an exploded perspective view of a main body of the sealing member. 4 is a side view showing a part of the main body of the sealing member in a cutaway view. FIG. FIG. 4 is a block diagram of an electrical system of the sealing member. FIG. 2 is a diagram showing a schematic view of a main part of a heat sealing device using the sealing member. FIG. 1A is a diagram showing an example of a waveform obtained by the sealing member, FIG. 1B is a diagram showing an example of a reference waveform, and FIG. 1C is a diagram showing the obtained waveform in comparison with the reference waveform. FIG. 6 is a diagram illustrating a schematic configuration of a heat-sealing device different from that in FIG. 5 .

Next, an embodiment of the present invention will be described in detail with reference to the drawings.
In Fig. 1, a sealing member 1 presses together a plurality of films in cooperation with a mating member. The sealing member 1 can be suitably used as one of a pair of sealing bodies that sandwich a film in a heat sealing device, as described later.

The main body 2 of the sealing member 1 has an elongated rectangular parallelepiped shape overall, and the upper surface in the figure is the contact surface 3 that contacts the film while facing the mating member and presses the film. The contact surface 3 has an elongated rectangular shape in a plan view, and a pressure receiving portion 4a of a pressure sensor 4 is embedded near the lower part of the contact surface 3, making it possible to detect pressure acting on a specified area directly below the contact surface 3. Note that the area shown by a two-dot chain line on the contact surface 3 in Figure 1 is the pressing area 3a that presses multiple films together with the mating member 41 (see Figure 3).

Figure 2 is an exploded view of the main body 2 of the sealing member 1. As shown in the figure, the main body 2 of the sealing member 1 includes an abutment member 6, an intermediate member 7, a pressure sensor 4, a shim plate 8, and a base body 9, and other components are stacked on the support surface 9a of the base body 9, which faces upward in the figure.

The abutment member 6 is located on the outermost surface of the main body 2, and the outer surface portion serves as the abutment surface 3 that comes into contact with the film. The edge portion extending in the longitudinal direction of the abutment member 6 is bent downwards, except for the portion where the notch portion 11 is formed, to form the bent portion 10. The bent portion 10 covers the edges of the intermediate member 7 and the shim plate 8, and is secured to the side of the base body 9 by a stop plate 12 shown by the two-dot chain line in Figure 3. The abutment member 6 can be made of a Teflon sheet (Teflon: registered trademark), which has excellent heat resistance and releasability.

The intermediate member 7 is a member disposed between the contact member 6 and the pressure sensor 4, and is configured to include elastic layers 20, 22 and a heat insulating layer 24. The elastic layers 20, 22 and the heat insulating layer 24 are all rectangular and approximately the same size as the support surface 9a of the base body 9, and in this example, the intermediate member 7 is formed in a form in which the heat insulating layer 24 is sandwiched between the elastic layers 20, 22.

The elastic layers 20 and 22 are elastically deformable sheet-like layers, and may be, for example, silicone rubber sheets. By interposing the elastic layers 20 and 22 between the contact surface 3 and the base body 9, it is possible to achieve a uniform pressure distribution in the longitudinally extending crimping region 3a when the film is crimped.

The insulating layer 24 is a sheet-like layer with low thermal conductivity, and can be, for example, a hard insulating board made by laminating glass fibers and solidifying them with an inorganic binder. The thermal conductivity is preferably 0.5 W/m·K or less. By interposing the insulating layer 24 between the contact surface 3 and the pressure sensor 4, it is possible to prevent the pressure sensor 4 from being exposed to high temperatures due to heat from a heater embedded in the mating member, and to prevent the pressure signal output from the pressure sensor 4 from fluctuating due to the influence of the heat from the heater.

The pressure sensor 4 is inserted into the main body 2 from a direction perpendicular to the longitudinal direction of the crimping area 3a. The pressure receiving part 4a at the tip of the pressure sensor 4 is located at a position overlapping the contact surface 3 when projected and observed in a direction perpendicular to the contact surface 3, and is supported by the support surface 9a of the base body 9. The pressure sensor 4 converts the pressure received by the pressure receiving part 4a into an electrical signal based on the change in the electrical resistance value of a metal resistor (not shown) formed in the pressure receiving part 4a, and outputs this electrical signal as a sensor signal (pressure signal). An example of the pressure sensor 4 is a strain sensor. In this example, pressure sensors 4A and 4B are arranged at two locations spaced apart in the longitudinal direction of the crimping area 3a, and pressure at one end of the longitudinal direction of the contact surface 3 and pressure at the other end can be detected. In the following description, when the pressure sensors 4A and 4B are referred to collectively, they will be referred to as "pressure sensor 4".

The shim plate 8 is a rectangular metal sheet of approximately the same size as the support surface 9a of the base body 9, with a cutout at the portion that overlaps with the pressure sensor 4 when they are stacked. The shim plate 8 is placed between the intermediate member 7 and the base body 9, in an area where the pressure sensors 4A and 4B are not placed, to prevent localized pressure increases in the area of the contact surface 3 that overlaps with the pressure sensor 4A or 4B, and to ensure uniform pressure distribution on the contact surface 3 when the film is pressed against it.

The base body 9 has a rigid block body made of a metal such as aluminum, and supports the pressure sensor 4, shim plate 8, and intermediate member 7 on its upward flat support surface 9a. On the other hand, a female screw hole 14 is formed in the downward flat bottom surface 9b located on the opposite side to the support surface 9a (see FIG. 3). The female screw hole 14 screws into a fixing bolt (not shown) used to fix the main body 2 to the stand 43 of the heat sealing device. That is, in the sealing member 1, the bottom surface 9b and the female screw hole 14 form the mounting portion of the present invention. The configuration of the mounting portion can be changed as appropriate to suit the heat sealing device to which it is attached.

A hole is formed in the base body 9 that extends longitudinally from the side of the block body, and a cartridge heater 16 is inserted as a heating means. In addition, as shown in FIG. 3, a fine hole is formed in the base body 9 that leads to the vicinity of the pressure receiving portion 4a of the pressure sensor 4, and a temperature sensor 18 is inserted in this fine hole, so that the temperature of the pressure sensor 4 or its surroundings can be measured by the temperature sensor 18. Thus, in this example, the base body 9 is a heater unit equipped with the heater 16 and the temperature sensor 18 as heating means. Note that the heating means used here is not limited to the above-mentioned cartridge heater, and it is also possible to configure the entire base body 9 as an aluminum cast heater, for example.

The sealing member 1 is equipped with a control circuit (not shown) as a temperature control means for controlling the current passed through the heater 16 of the base body 9. The temperature sensor 18 and the heater 16 are electrically connected to the control circuit. The control circuit is configured to pass a current through the heater 16 based on the difference between a preset target temperature and the temperature detected by the temperature sensor 18. In this example, the pressure receiving portion 4a of the pressure sensor 4 and its surrounding area are maintained at a predetermined temperature (e.g., 70°C) that is equal to or higher than room temperature, thereby suppressing the variation in the pressure signal caused by temperature changes in the pressure sensor 4.

4 is a block diagram of the electrical system of the sealing member 1. As shown in the figure, the pressure sensors 4A, 4B and the temperature sensor 18 provided in the main body 2 are connected to an amplifier unit 27, which is further connected to a computer 32.
The amplifier unit 27 has an amplifier 28, an A/D converter 29, and a communication port 30. The pressure signals output from the pressure sensors 4A and 4B are amplified by the amplifier 28 and then converted into digital signals by the A/D converter 29. The temperature signal output from the temperature sensor 18 is also amplified by the amplifier 28 and then converted into digital signals by the A/D converter 29. In order to obtain a highly accurate pressure waveform in the calculation processing unit 34 described later, it is desirable to set the sampling interval of the pressure signal to 5 ms or less. Note that if there is no need to amplify the signals obtained from the sensors, the amplifier 28 can be omitted.

These converted digital signals are sent to the computer 32 via the communication port 30. The communication between the communication port 30 of the amplifier unit 27 and the receiving port 33 of the computer 32 is preferably transmitted using a USB cable, but Wi-Fi or Bluetooth (registered trademark) can also be used.

The computer 32 includes a receiving port 33 , an arithmetic processing unit 34 , a storage unit 35 including a storage device such as a hard disk drive (HDD), and a display unit 36 .
The arithmetic processing unit 34 converts the pressure signal received via the receiving port 33 into a pressure value in a unit recognizable by humans (e.g., N or Kg/ ^m2 ), and generates a waveform that represents the change in pressure over time. The obtained pressure waveform can be displayed on the display unit 36 (an example of the waveform is shown in FIG. 6(A)). Here, since the pressure signals from the pressure sensors 4A and 4B vary with temperature, the arithmetic processing unit 34 can also correct the pressure value according to the temperature of the pressure sensor (i.e., the temperature detected by the temperature sensor 18).

The calculation processing unit 34 can also compare the shape of the obtained pressure waveform with the shape of a predetermined reference waveform to determine whether it is normal or abnormal. The determination can be made by combining multiple evaluation elements such as the area of the waveform and the maximum peak. The obtained determination result can be displayed on the display unit 36 and stored in the memory unit 35.

The calculation processing unit 34 can be a processor such as a CPU. In this case, it is realized by the processor such as a CPU executing a control program stored in a ROM or the like. Thus, in this example, the amplifier unit 27 and the computer 32 constitute the waveform acquisition means of the present invention.

Next, a heat-sealing device 40 in which the sealing member 1 of this embodiment is used will be described.
The heat sealing device 40 shown in FIG. 5 is incorporated into the bag making machine as part of the machine and heat seals the films F1 and F2, which are the material for the bags, that are fed intermittently together in the width direction of the films.

The heat sealing device 40 comprises an upper sealing body 41 as a first sealing body and a lower sealing body 42 as a second sealing body, and the above-mentioned sealing member 1 (more specifically, the main body portion 2 of the sealing member 1) is used as the lower sealing body 42.
The upper seal body 41 and the lower seal body 42 are elongated in a direction perpendicular to the film transport direction (the left-right direction in FIG. 5) and are disposed opposite to each other.

The upper seal body 41 is a seal body that can be raised and lowered, and is attached to the upper holding plate 45. The upper seal body 41 has a built-in heater (not shown), and the tip of the upper seal body 41 can be heated to a predetermined sealing temperature (e.g., 200°C).

The lower seal body 42 is a receiving member that receives the load of the upper seal body 41, and is fixedly attached to the stand 43 of the heat sealing device 40. In this example, the sealing member 1 used as the lower seal body 42 is fixed to the stand 43 of the heat sealing device 40 by a fixing bolt that is screwed into the female threaded hole 14 (see FIG. 3) provided on the bottom surface 9a of the base body 9 of the sealing member 1.

In the heat sealing device 40, rod-shaped slide shafts 44A and 44B are arranged on both sides in the left-right direction perpendicular to the film transport direction. A lifting member 52 and a motor 53 as a driving means are connected to the base ends of the slide shafts 44A and 44B. The lifting member 52 is made up of a link mechanism and a cam mechanism, and converts the rotational motion of the motor 53 into up-down (lifting) motion and transmits it to the slide shafts 44A and 44B. This allows the slide shafts 44A and 44B to be raised and lowered.

On the other hand, a first flange portion 47 and a second flange portion 48 are provided along the axial direction on the upper end side of the slide shafts 44A and 44B, respectively, and the upper surface of the first flange portion 47 supports the upper holding plate 45, and a compressed spring member 50 is wound between the upper holding plate 45 and the second flange portion 48.

When the heat sealing device 40 configured in this manner starts making bags, each time the films F1 and F2 that are the raw material for the bags stop intermittently, the upper seal body 41 descends and the downward contact surface of the upper seal body 41 comes into contact with the contact surface 3 of the lower seal body 42 via the film. Next, based on the downward spring force of the spring member 50, the contact surface of the upper seal body 41, which has been heated to a predetermined temperature, is pressed against the films F1 and F2, and heat sealing (thermal fusion) is performed.

At the same time, in the heat sealing device 40, at a predetermined sampling interval, the pressure signal detected by the pressure sensors 4A and 4B and the temperature signal detected by the temperature sensor 18 near the pressure sensor are sent to the computer 32 via the amplifier unit 27, and a pressure waveform as shown in Figure 6 (A) is generated in the calculation processing unit 34 and displayed on the display unit 36.

Figure 6 (A) shows a waveform 60 obtained based on a pressure signal from one pressure sensor 4A, and omits the waveform based on the other pressure sensor 4B, but it is also possible to display these two waveforms together on the display unit 36.

In this example, a normal/abnormal judgment can be made based on the shape of the obtained pressure waveform 60. The judgment can be made by the operator by looking at the shape of the waveform displayed on the display unit 36, but a desirable pressure waveform for each property of the film used can be registered in advance in the memory unit 35 of the computer 32 as a reference waveform 61 (see FIG. 6(B)). The calculation processing unit 34 compares the shape of the waveform 60 obtained for each sealing operation with the shape of the reference waveform 61, and as shown in FIG. 6(C), if the shape of the obtained waveform 60 differs from the shape of the reference waveform 61 (if the regulations are not met for any evaluation element, such as the maximum peak), an abnormality can be judged.

As described above, the sealing member 1 of this embodiment can detect the pressure acting on a specific area directly below the contact surface 3 where the films are actually pressed when the sealing member 1 cooperates with a mating member to press multiple films together, and can check and evaluate the sealing conditions based on the obtained pressure signal.

The sealing member 1 of this embodiment is equipped with a waveform acquisition means for acquiring a waveform representing the change in pressure over time based on the pressure signal from the pressure sensor 4, and the sealing conditions can be confirmed and evaluated based on the shape of the pressure waveform 60 that changes over time.

In the sealing member 1 of this embodiment, a sheet-shaped insulating layer 24 is provided between the contact surface 3 and the pressure sensor 4, which prevents the pressure sensor 4 from being exposed to high temperatures due to heat from a heater embedded in the mating member, and prevents the pressure signal output from the pressure sensor 4 from fluctuating due to the influence of the heat from the heater.

In the sealing member 1 of this embodiment, the base body 9 is a heater unit including a heater 16 for heating, so that the temperature of the pressure sensor 4 can be controlled within a predetermined temperature range above room temperature, and variations in the pressure signal output from the pressure sensor 4 due to temperature changes in the pressure sensor 4 can be suppressed.

In the sealing member 1 of this embodiment, a shim plate 8 is placed between the contact surface 3 and the base body 9 in an area where the pressure sensor 4 is not placed, and the pressure distribution on the contact surface 3 when the film is pressed is adjusted, so that localized increases in pressure can be suppressed in the area of the contact surface 3 that overlaps with the pressure sensor 4.

In the sealing member 1 of this embodiment, elastically deformable sheet-like elastic layers 20, 24 are provided between the contact surface 3 and the pressure sensor 4, and when the film is pressed, the pressure distribution can be made uniform within the contact surface 3, specifically, in the pressing area 3a where the film is pressed in cooperation with the opposing member.

In the sealing member 1 of this embodiment, the pressure sensors 4 are inserted into the sealing member 1 from a direction intersecting the longitudinal direction of the crimping region 3a, and are spaced apart in the longitudinal direction of the crimping region 3a, so that the pressure can be detected at multiple points within the contact surface 3.

The sealing member 1 of this embodiment has an attachment portion that can be attached to the heat sealing device 40, and can be easily retrofitted to an existing heat sealing device 40.

<Other modified examples and application examples>
Although the embodiments of the present invention have been described in detail above, these are merely examples, and the present invention can be configured in various modified forms without departing from the spirit of the present invention.
(1) In the above embodiment, an intermediate member including an elastic layer and a heat insulating layer is provided between the contact surface of the sealing member and the pressure sensor, but the number and thickness of the elastic layer and the heat insulating layer included in the intermediate member can be changed as appropriate. In some cases, it is also possible to adopt a sealing member that does not include an intermediate member. In this case, the pressure receiving surface of the pressure sensor can be disposed nearly flush with the contact surface, and the pressure acting on a predetermined area of the contact surface can be detected directly (without passing through the intermediate member) by the pressure sensor.

(2) In the above embodiment, the pressure sensors are provided at two locations spaced apart in the longitudinal direction of the sealing member, but the locations and number of pressure sensors can be changed as appropriate. In some cases, it may be possible to use a pressure sensor with a wide detection area so that a wide area within the contact surface can be measured with a single pressure sensor.

(3) The above embodiment is an example of a heat sealing device equipped with an upper seal body whose tip is heated to a predetermined sealing temperature and a lower seal body whose tip is not heated to the sealing temperature, in which the lower seal body is made of the sealing member of the present invention. However, in the case of a heat sealing device in which both the upper seal body and the lower seal body are heated to a predetermined sealing temperature, either the upper seal body or the lower seal body can be made of the sealing member of the present invention.

(4) Figure 7 shows an example in which the sealing member 1 is applied to a heat sealing device 40B different from that shown in Figure 5. In the example shown in Figure 7, the position of the spring member 50 that applies a downward pressing force to the upper seal body 41 is different, and the point of application P of the downward pressing force acting on the lower seal body 42 via the upper seal body 41 is located within the contact surface 3 of the lower seal body 42 (i.e., the sealing member 1). In such a case, by arranging the pressure receiving portion 4a of the pressure sensor 4 embedded in the sealing member 1 directly below the point of application P and at a position where the line of action extending downward from the point of application P passes through, pressure adjustment can be easily performed based on the signal output from the pressure sensor 4.

(5) The above embodiment is an example in which the sealing member of the present invention is applied to a heat sealing device incorporated in a bag making machine, but the sealing member of the present invention can also be applied to heat sealing devices used for purposes other than bag making machines (e.g., filling machines, etc.).

REFERENCE SIGNS LIST 1 Sealing member 3 Contact surface 4, 4A, 4B Pressure sensor 4a Pressure receiving portion 8 Shim plate 9 Base body 9b Bottom surface (mounting portion)
14 Female thread hole (mounting part)
16 heater 20, 22 elastic layer 24 heat insulating layer 27 amplifier unit (waveform acquisition means)
32 Computer (waveform acquisition means)
40, 40B Heat sealing device 41 Upper sealed body (first sealed body)
42 Lower seal body (second seal body)
F1, F2 Film 60 Waveform P Action point

Claims (7)

A sealing member that presses together a plurality of films in cooperation with a mating member,
a contact surface that contacts the film;
a pressure sensor having a pressure receiving portion provided at a position overlapping with the contact surface when projected and observed in a direction perpendicular to the contact surface;
an intermediate member including a sheet-like insulating layer and disposed between the contact surface and the pressure sensor;
A base body supporting the pressure sensor;
a shim plate having a cutout at a portion that overlaps with the pressure sensor when the two are superimposed, the shim plate being disposed between the intermediate member and the base body and in an area where the pressure sensor is not disposed;
A sealing member comprising: The sealing member according to claim 1, further comprising a waveform acquisition means for acquiring a waveform representing a time change in pressure based on a pressure signal from the pressure sensor. A sealing member as described in any one of claims 1 to 2 , characterized in that a temperature sensor is provided on the base body supporting the pressure sensor, and the temperature of the pressure sensor or its surrounding area can be measured by the temperature sensor . 4. The sealing member according to claim 1 , wherein the intermediate member further includes a sheet-like elastic layer that is elastically deformable. 5. The sealing member according to claim 1 , further comprising an attachment portion, which is configured so as to be attachable to a heat-sealing device via the attachment portion. A heat sealing device comprising a first sealing body and a second sealing body disposed opposite the first sealing body, the device sandwiching a plurality of films between the pair of sealing bodies and applying heat and pressure to the films to perform heat sealing,
A heat-sealing device, wherein the first seal body or the second seal body is made of the sealing member according to any one of claims 1 to 5 . 7. The heat sealing device according to claim 6, characterized in that the pressure receiving portion of the pressure sensor is arranged at a position where a line of action of a pressing force acting on either the first seal body or the second seal body via the other seal body passes.

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