JP2024011345A - vacuum packaging machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vacuum packaging machine capable of suppressing plastic-deformation of a heater wire.

SOLUTION: In a vacuum packaging machine having a sealing step of holding an opening of a wrapping material having a packaged object housed therein by upper and lower seal blocks disposed in its chamber, and energizing a heater wire to seal the opening of the wrapping material during vacuum packaging, the sealing step is performed before a pre-heating step.

SELECTED DRAWING: Figure 5

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a vacuum packaging machine that can suppress plastic deformation of heater wires.

2. Description of the Related Art Vacuum packaging machines have been developed that vacuum pack multiple packaging materials (packaging bags) at the same time. The vacuum packaging machine uses a long nichrome heater wire (hereinafter referred to as a long heater wire) in order to simultaneously seal a plurality of packaging materials during vacuum packaging. When a long heater wire is used, it is known that the long heater wire that undergoes linear expansion during sealing has nowhere to escape, causing plastic deformation such as bulges, depressions, and meandering.

When sealing, for example, four packaging materials at the same time that have at least some thick packaging materials, the pressure of the upper sealing block presses packaging material a, packaging material b, packaging material c, packaging material d, etc. at the same time. Ru. As a result, the long heater wires located between packaging material a and packaging material b, between packaging material b and packaging material c, and between packaging material c and packaging material d have no place to escape, causing bulges, depressions, meandering, etc. occurs, causing plastic deformation. If such plastic deformation occurs repeatedly, there is a risk that the long heater wire may be damaged or disconnected, which may lead to a situation where the long heater wire must be replaced.

Japanese Patent Application Publication No. 2004-161291 Japanese Patent Application Publication No. 2002-145210

The problem to be solved by the present invention is to solve the above-described problems, and to provide a vacuum packaging machine that can suppress plastic deformation of a heater wire.

The vacuum packaging machine of the embodiment clamps the opening of the packaging material containing the packaged material between upper and lower seal blocks provided in the chamber during vacuum packaging, and energizes the heater wire during the sealing process to clamp the packaging material. The vacuum packaging machine for sealing the opening of the packaging material is characterized in that a preheating step is performed before the sealing step.

FIG. 1 is a perspective view showing the structure of a vacuum packaging machine according to an embodiment. FIG. 2 is a diagram showing a plurality of packaging materials arranged in the vacuum packaging machine according to the embodiment. They are a front view, a top view, and a right side view of the vacuum packaging machine according to the embodiment with the lid opened. FIG. 2 is an enlarged cross-sectional view of the chamber of the vacuum packaging machine according to the embodiment with the lid closed. It is a diagram showing the configuration of upper and lower seal blocks and heater wires of the vacuum packaging machine according to the embodiment. (a) and (b) are diagrams illustrating control of upper and lower seal blocks and heater wires in a standby state and preheating. (c) and (d) are diagrams illustrating control of the upper and lower seal blocks and heater wires in the lowering process of the upper seal block and the sealing process. It is a figure which shows the control in a chamber in the standby state and preheat state of FIG.6(a)(b). It is a figure which shows the control in the lowering process of the upper seal block of FIG.7(c). It is a figure which shows the control in the sealing process of FIG.7(d). It is a flow chart which shows control of a heater wire by a control device of an embodiment. It is a figure which shows the example of a graph of the test data of linear expansion when a preheating process is performed to the heater wire of embodiment. As a comparative example, it is a diagram showing an example of a graph of linear expansion test data when the heater wire is not subjected to a preheating process.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a perspective view showing the structure of a vacuum packaging machine having a long heater wire. FIG. 2 is a diagram showing a plurality of packaging materials (packaging bags, for example, plastic bags) arranged in the same vacuum packaging machine. FIG. 3 is a front view, a top view, and a right side view of the vacuum packaging machine with the lid open. FIG. 4 is an enlarged sectional view of the chamber of the same vacuum packaging machine with the lid closed. FIG. 5 is a diagram showing the structure of the upper and lower seal blocks and heater wires of the vacuum packaging machine.
The shape and structure of a vacuum packaging machine having a long heater wire will be described below with reference to FIGS. 1 to 5. Note that, in FIGS. 1 to 5, the same components are given the same reference numerals, and duplicate explanations of the configurations will be omitted.

As shown in FIGS. 1 to 3, the vacuum packaging machine 10 according to the embodiment has a chamber 30 formed on the top surface of a cubic housing 20 that is longer in the horizontal direction (longitudinal direction) than in the vertical direction (short direction). A flat plate 40 is provided. The plate 40 is made of stainless steel, for example. The plate 40 has, for example, a width of 80 cm, a length of 50 cm, and a height of 5 cm. An operation panel 50 is provided on the front of the vacuum packaging machine 10. A lid 70 is attached to the rear end of the plate 40 via left and right hinge mechanisms 60. The lid 70 is made of aluminum, for example. A handle 75 for opening and closing is provided on the front side of the lid 70, and one or more peep holes 80 are provided on the top surface through which the vacuum packaging state of the plurality of packaging materials 150 can be seen during vacuum operation. There is.

FIG. 4 is an enlarged cross-sectional view of the chamber 30. As shown in FIG. 4, a lower seal block 90 provided in the longitudinal direction is provided on the back side (hinge side) of the plate 40 of the vacuum packaging machine 10. An upper seal block 100 is provided inside the lid 70 facing the lower seal block 90. The lower seal block 90 and the upper seal block 100 constitute a seal (sealing) mechanism, and the lower seal block 90 is provided with a long heater wire for sealing (see FIGS. 5 and 6), which will be described later. ing. The upper seal block 100 is controlled to descend/raise in order to simultaneously pinch the tip openings (bag openings) of a plurality of packaging materials 150 (see FIG. 2) prior to the sealing process and to release them later. Then, in the sealing process, while the tip openings of the plurality of packaging materials 150 are simultaneously sandwiched, electricity is applied to the long heater wire laid in the lower seal block 90 to generate heat, so that the plurality of packaging materials 150 simultaneously seal the tip opening. The packaging material 150 can be applied not only to thick packaging materials but also to ordinary packaging materials.

Identical locking members 120 and 130 (see FIG. 1 or 2) having a plurality of slits 110 formed at predetermined intervals are provided on both sides of the chamber 30 in the lateral direction. The locking members 120 and 130 are fixed to both bottom surfaces of the plate 40. A partition plate 140 (see FIG. 2) is removably connected to the slits 110 of the locking members 120 and 130 at the same scale position. This partition plate 140 allows the rear ends of the plurality of packaging materials 150 to be positioned in the lateral direction of the plate 40. The partition plate 140 is positioned by inserting it into the slits 110 of the locking members 120 and 130 at the same scale position according to the size of the packaging material 150. As a result, as shown in FIG. 2, vacuum packaging is performed by placing a plurality of packaging materials 150 between the sealing mechanism of the vacuum packaging machine 10 and the partition plate 140.

Further, as shown in FIG. 4, an inclined guide member 170 that guides the plurality of packaging materials 150 is provided close to (parallel to) the front side (handle side) of the lower seal block 90. The inclined guide member 170 has approximately the same length as the lower seal block 90 in the longitudinal direction. The tilt angle of the tilt guide member 170 can be changed by, for example, providing a pedestal on the bottom surface of the chamber 30. With this inclined guide member 170, when the tip openings of the plurality of packaging materials 150 are placed on the lower seal block 90, the packaging materials 150 are moved in an oblique direction between the lower seal block 90 and the bottom surface of the plate 40. Guide. On the opposite side (hinge side) of the inclined guide member 170, a steam guard 180 is provided close to (parallel to) the lower seal block 90.

Steam guard 180 has approximately the same length as lower seal block 90 in the longitudinal direction. The steam guard 180 has a horizontal surface portion 180a having approximately the same height as the upper surface of the lower seal block 90, and a raised portion 180b measuring several centimeters formed at the far end of the horizontal surface portion 180a. That is, the rising portion 180b is formed on the tip side of the horizontal surface portion 180a on the opposite side (hinge side). The rising part 180b is configured to prevent, for example, even if the liquid in the packaging material 150 containing the liquid boils and the liquid spouts out from the opening of the packaging material 150 when the lid 70 is closed and the pressure inside the chamber 30 is reduced. , serves as a wall that does not leak to the outside, and also serves to stop overflowing liquid on the horizontal surface portion 180a. The overflowing liquid is at least partially vaporized and any remaining liquid is wiped off after the operation.

For example, when a plurality of packaging materials 150 containing liquid are vacuum-packaged at the same time, a large amount of water vapor is generated within the chamber 30, which is expected to have a negative effect on the vacuum pump. In the vacuum packaging machine 10, even if liquid overflows from the packaging material 150 during vacuum packaging, it can be retained on the steam guard 180 due to the structure of the rising portion 180b. By condensing the water vapor (at least a portion) on the steam guard 180, the amount of water vapor in the chamber 30 can be suppressed, and as a result, it is possible to prevent an adverse effect on the vacuum pump.

Furthermore, an auxiliary block 190 is provided between the lower seal block 90 and the inclined guide member 170 in parallel in the longitudinal direction. An adhesive (removable) is applied to the upper surface of the auxiliary block 190 to weakly adhere the tip of the packaging material 150. Further, an adhesive that weakly adheres the tip of the packaging material 150 may also be applied to the horizontal surface portion 180a of the steam guard 180 near the lower seal block 90. Alternatively, a second auxiliary block may be provided between the lower seal block 90 and the steam guard 180. An adhesive is also applied to the upper surface of the second auxiliary block to weakly adhere the leading end of the packaging material.

Further, as shown in FIG. 4, an expansion attachment member 200 is attached in the longitudinal direction close to (parallel to) the upper seal block 100 inside the lid 70. Inflatable mounting member 200 is slightly longer than lower seal block 90 and upper seal block 100. The expansion mounting member 200 includes mounting pieces 200b provided on both sides in which guide holes are formed, and a connecting portion 200c that connects the mounting pieces 200b (in the longitudinal direction). Then, the expansion detection member 210 is attached in the longitudinal direction so as to be slidable along the guide hole. The expansion detection member 210 detects expansion of a packaging material (hot pack) containing a liquid during vacuum packaging. Detection by the expansion detection member 210 is not performed in the case of a seal for a packaging material containing a packaged object that is not a liquid.

FIG. 5 is a diagram showing the configuration of the upper and lower seal blocks 90, 100 and the heater wire 300 of the vacuum packaging machine 10. On the upper surface of the lower seal block (also referred to as a heater block) 90, a long heater wire 300 having a predetermined width is laid in a straight line. An upper seal block (also referred to as a seal receiving member) 100 is provided above the lower seal block 90, facing the lower seal block 90 (having the same width and length). A sealing operation is performed by placing the plurality of packaging materials (for example, plastic bags) 150 with the openings to be sealed on the long heater wires 300 of the lower seal block 90. Both ends of the long heater wire 300 are fixedly connected by a screw 320 via a leaf spring 310. The leaf spring 310 applies tension to the long heater wire 300. The screw 320 is also a member that fixes the leaf spring 310. The long heater wire 300 is energized to perform a preheating process and a heating process by a control device 500, which will be described later.

6 and 7 are diagrams showing the operations of the lower seal block 90, the upper seal block 100, and the long heater wire 300 in the vacuum packaging process of the vacuum packaging machine.
FIG. 6A shows a standby state when the lid 70 is closed, and the lower seal block 90 and the upper seal block 100 are on standby with a predetermined distance apart.

FIG. 6(b) shows the form of the long heater wire 300 at the time of transition to the preheating step. In FIG. 6(b), the long heater wire 300 is elongated by passing current through the long heater wire 300 for a short time (preheating time is about 1 second, for example) and applying weak heat (indicated by a dotted line). ing. That is, before the sealing process, linear expansion is generated in the long heater wire 300, and a flat state is formed by the tension of the leaf spring 310. The weak heat at this time is a temperature at which the opening of the packaging material 150 does not melt. The preheating time depending on the material of the packaging material can be easily obtained from preliminary test data.

FIG. 7(c) is a process of evacuating the inside of the plurality of packaging materials 150 by activating the vacuum pump to create a vacuum inside the chamber 30. In order to seal the openings of the plurality of packaging materials 150, for example, The upper seal block 100 is shown in a lowered state. As a result, the openings of the plurality of packaging materials 150 are sandwiched between the upper and lower seal blocks 90 and 100.

FIG. 7D shows a state in which the long heater wire 300 is energized to perform a heating process (also referred to as main sealing) with the openings of the plurality of packaging materials 150 being sandwiched. In FIG. 7(d), the long heater wire 300 is displayed thickly to indicate that the current for the sealing process (for a period of time equal to the sealing setting number of seconds) is flowing. As a result, the openings of the plurality of packaging materials 150 are melted by the heat, and the sealing is completed. The energization time in the sealing process is determined according to the temperature increased in the preheating process. In other words, the energization time in the sealing process that uses the preheating process is shorter than the energization time in the sealing process that does not use the preheating process.

Next, the operation of the vacuum packaging machine 10 and the control of the long heater wire 300 will be described with reference to FIGS. 8 to 11.
FIG. 8 shows the operation control of the chamber 30 in the standby state of FIG. 6(a) and the preheating process state of FIG. 6(b). FIG. 9 shows the operation control of the chamber 30 during the lowering process of the upper seal block 100 in FIG. 7(c). FIG. 10 shows the operation control of the chamber 30 in the sealing step of FIG. 7(d). Note that operations not directly related to this embodiment are omitted. FIG. 11 is a flowchart showing the control operation of the long heater wire 300 by the control device 500 in the preheating step of FIG. 6(b) and the sealing step of FIG. 7(d).

The control mechanism of the vacuum pump shown in FIGS. 8 to 10 includes a control device 500, a vacuum pump 510, a vacuum solenoid valve 520, a soft solenoid valve 530, a seal opening/closing solenoid valve (three-way solenoid valve) 540, a soft opening solenoid valve 550, and a vacuum opening. It is composed of a solenoid valve 560. At least a lid opening/closing sensor signal, an expansion detection signal, a pressure sensor signal, etc. are input to the control device 500 in order to execute a vacuum packaging operation. Then, the control device 500 outputs control signals S1 to S5 that control the opening and closing of each of the electromagnetic valves described above. Further, the control device 500 outputs a heater wire control signal to the long heater wire 300 for energizing the long heater wire 300 for a set time.

Note that although FIGS. 8 to 10 show only one packaging material (for example, a plastic bag) 150 since the views are shown from the side, it should be understood that a plurality of packaging materials 150 are placed. Further, the configuration inside the chamber 30 is shown in a simplified manner. Furthermore, in the sealing process, the upper seal block 100 is controlled to descend/raise, but its intake passage is omitted. Moreover, here, in order to uniformly vacuum pack a plurality of packaging materials 150, vacuuming is performed by changing the vacuum value in stages, but a single vacuuming step may be sufficient. In the sealing process, instead of controlling the upper seal block 100 to lower/lower, the lower seal block 90 may be controlled to rise/lower.

First, the packaging material 150 containing the object to be packaged is set in the chamber 30. In the setting process, with the lid 70 open, an operator places the packaging material 150 on the chamber 30 of the plate 40 and places the tip opening (packaged article inlet) on the lower seal block 90. When the lid 70 is closed by hand after the packaging material 150 is set, a lid open/close detection sensor (not shown) detects the closed state of the lid 70 and sends a signal to the control device 500.

In FIG. 8, when the lid 70 is closed, a step of evacuation to 15% is performed. The control device 500 opens the vacuum solenoid valve 520 and closes the soft solenoid valve 530 to bring the intake passage 600 between the chamber 30 and the vacuum pump 510 into an intake communication state. Further, among the seal opening/closing solenoid valve (three-way solenoid valve) 540, the connection port on the atmosphere opening side and the connection port on the seal closing drive channel 610 are opened, and the connection port on the pump 510 side is closed. Note that the operating state of the vacuum pump 510 is maintained until the lid 70 is opened. Further, the closed state of the vacuum release solenoid valve 560 is maintained until the seal cooling process is completed.

The control device 500 operates the vacuum pump 510 to start reducing the pressure in the chamber 30 and degas the packaging material 150. As a result, the air inside the chamber 30 is sucked into the vacuum pump 510 through the vacuum electromagnetic valve 520 and the intake flow path 600, so that the inside of the chamber 30 is evacuated. Then, the control device 500 evacuates (depressurizes) the pressure inside the chamber 30 to 15% while checking the signal from a pressure detection sensor (not shown). In this standby state, the long heater wire 300 is preheated.

The control device 500 performs the preheating process shown in FIG. 6(b) in the state shown in FIG. That is, as shown in FIG. 11, the control device 300 preheats the long heater wire 300 at a temperature at which the packaging material 150 does not melt. Note that it is desirable that the temperature be automatically set (including disabled) in accordance with the temperature of the sealing process (S100).
In this way, by performing the preheating shown in FIG. 6(b), it is possible to reduce the temperature difference in the long heater wire 300 while it is being held between the upper and lower seal blocks 90 and 100, thereby reducing linear expansion. It can be made smaller.

FIG. 9 is a diagram showing the operation of the vacuum pump 510 by controlling the electromagnetic valve and the release valve in the process of sealing the opening of the packaging material 150 and evacuating it to 40%. From the state shown in FIG. 8, the control device 500 closes the connection port on the atmosphere-opening side of the seal opening/closing solenoid valve (three-way solenoid valve) 540, and closes the connection port on the seal closing drive flow path 610 and the pump side. Leave the connection port open. When the atmospheric pressure in the chamber 30 has been reduced to 15%, the upper seal block 100 is lowered by sucking air into the closing cylinder 620 through the seal closing drive flow path 610, and the lower seal block 90 and the lower seal block 90 are lowered. The opening of the packaging material 150 is sandwiched between the upper seal block 100 and the opening of the packaging material 150 to be sealed. After the opening of the packaging material 150 is sealed, the control device 500 evacuates (depressurizes) the inside of the chamber 30 to 40%. This forms the state shown in FIG. 7(c).

FIG. 10 is a diagram showing the operation of the vacuum pump by controlling the electromagnetic valve and the release valve in the sealing process. The long heater wire 300 is energized with the soft release electromagnetic valve 550 closed and the tip opening of the packaging material 150 sandwiched and sealed between the lower seal block 90 and the upper seal block 100. As shown in FIG. 11, in this sealing step, the long heater wire 300 is energized for a sealing set number of seconds depending on the material of the packaging material, and the opening of the vacuum-treated packaging material 150 is sealed ( S200).

To open the atmosphere, the vacuum release solenoid valve 560 is opened, and the connection port on the atmosphere release side of the seal opening/closing solenoid valve (three-way valve) 540 and the connection port of the seal closing drive flow path 610 are opened. The connection port on the pump 510 side is closed. Thereby, the inside of the chamber 30 is returned to atmospheric pressure, and the vacuum-packed packaging material 150 can be taken out.

FIG. 12 shows a graph of test data of linear expansion due to temperature difference of the long heater wire 300 while the packaging material 150 is being held between the long heater wires 300 when the long heater wires 300 are subjected to a preheating process. In this test, the length of the heater wire 300 is, for example, 995 mm.
After the start of the test operation, the long heater wire 300 is energized for about 1 second as a preheating step. Then, the temperature of the long heater wire 300 increased from the original temperature of 33°C to 91°C. After the clamping waiting time (about 1 second) due to the lowering of the upper seal block 100 after the energization was turned off in the preheating process, the temperature decreased from 91°C to 80°C. Thereafter, in a sealing step, the long heater wire 300 was energized for about 3 seconds to seal the opening of the packaging material 150. By energizing the seal for 3 seconds, the temperature rose from 80°C to 188°C. That is, the temperature difference in the long heater wire 300 while the packaging material 150 is being held is 188°C - 80°C = 108°C. As a result, when the temperature of the long heater wire 300 rose from 80° C. to 188° C. by performing the preheating step, the linear expansion was 1.83 mm.
According to experimental results, the time for energizing the long heater wire 300 in the preheating step is preferably 0.6 seconds to 1 second.

FIG. 13 shows a graph of test data of linear expansion due to temperature difference of the long heater wire 300 while the packaging material 150 is being held, when the preheating process is not performed as a comparative example.
After the start of the test operation, electricity is applied to the long heater wire 300 for about 3 seconds in the sealing process. Then, the temperature of the long heater wire 300 increased from the original temperature of 33°C to 188°C. The temperature difference in the heater wire 300 while sandwiching the packaging material 150 is 188°C - 33°C = 155°C. As a result, when the temperature of the long heater wire 300 rose from 33°C to 188°C, the linear expansion was 2.62 mm.
Note that the linear expansion dimension can be expressed by the following formula.
Linear expansion dimension ΔL=α×L×Δt
α = coefficient of linear expansion, L = length of the long heater wire 300,
Δt = amount of change in temperature (temperature after change - original temperature)

As is clear from the comparison of the test data in Figures 12 and 13, the linear expansion without the preheating process is 2.62mm, whereas in the embodiment that uses the preheating process, the linear expansion is suppressed to 1.83mm. I was able to do that. That is, since linear expansion during the sealing process can be suppressed to a small level, deterioration (damage, disconnection, etc.) of the long heater wire 300 can be reduced. Although an example in which the long heater wire 300 is installed in the lower seal block 90 has been described here, the present invention can also be applied to an example in which the long heater wire 300 is installed in the upper seal block 100. Further, the present invention can also be applied to a structure in which long heater wires are installed in both the lower seal block 90 and the upper seal block 100.

As described above, during vacuum packaging, the vacuum packaging machine of the embodiment sandwiches the opening of the packaging material 150 containing the packaged item between the upper and lower seal blocks 90, 100 provided in the chamber 30, and seals the packaging material. In a vacuum packaging machine that energizes the heater wire 300 during the process to seal the opening of the sandwiched packaging material 150, a preheating process (S100) is performed before the sealing process (S200). Thereby, by employing the preheating process, linear expansion during the sealing process can be suppressed to a small level, so that plastic deformation such as upheaval, depression, meandering, etc. of the heater wire 300 can be suppressed to a small level. As a result, deterioration due to breakage or disconnection of the heater wire 300 can be prevented.

Moreover, the heater wire 300 of the vacuum packaging machine of the embodiment has a length that can seal a plurality of packaging materials 150 at the same time, and is laid under tension on the lower side, the upper side, or the upper and lower sealing blocks. As a result, plastic deformation of the heater wire 300, such as upheaval, depression, meandering, etc., can be suppressed to a minimum, especially in the case of a long heater wire.

Moreover, the vacuum packaging machine of the embodiment is configured to reduce the temperature difference of the heater wire 300 while the packaging material 150 is being held between the packaging materials 150 and 150 by a preheating process. Thereby, plastic deformation of the heater wire 300 such as upheaval, depression, meandering, etc. can be suppressed to a small level.

Further, the vacuum packaging machine of the embodiment is configured to automatically vary the temperature of the preheating process in accordance with the temperature of the sealing process. Thereby, plastic deformation of the heater wire 300 such as upheaval, depression, meandering, etc. can be suppressed to a small level.

Further, in the vacuum packaging machine of the embodiment, the time period during which the heater wire 300 is energized in the preheating step is 0.6 seconds to 1 second. Thereby, plastic deformation of the heater wire 300 such as upheaval, depression, meandering, etc. can be suppressed to a small level.

Further, in the vacuum packaging machine of the embodiment, the energization time in the sealing process is set to a time corresponding to the temperature increased in the preheating process. Thereby, plastic deformation of the heater wire 300 such as upheaval, depression, meandering, etc. can be suppressed to a small level.

Further, in the vacuum packaging machine of the embodiment, the heat generated in the preheating step is set to a temperature at which the packaging material 150 does not melt. Thereby, plastic deformation of the heater wire 300 such as upheaval, depression, meandering, etc. can be suppressed to a small level.

The vacuum packaging machine of the embodiment also includes a chamber 30, upper and lower seal blocks 90 and 100 that are provided in the chamber 30 and sandwich the opening of the packaging material 150 that accommodates the object to be packaged during vacuum packaging, and lower seal blocks 90 and 100. Alternatively, it includes a heater wire 300 that is laid under tension on the upper or upper seal blocks, and a control means 500 that energizes the heater wire 300 during the sealing process to seal the opening of the sandwiched packaging material 150. In order to reduce the temperature difference of the heater wire 300 while the packaging material 150 is being held, the control means 500 is configured to conduct a preheating step by energizing the heater wire 300 before the sealing step. Thereby, by employing the preheating process, linear expansion during the sealing process can be suppressed to a small level, so that deterioration due to breakage or disconnection of the heater wire 300 can be prevented.

The embodiments of the invention are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included within the scope and gist of the invention, as well as within the scope of the invention described in the claims and its equivalents.

DESCRIPTION OF SYMBOLS 10...Vacuum packaging machine, 20...Cubic housing, 30...Chamber 40...Plate, 50...Operation panel, 60...Hinge mechanism, 70...Lid 80...Peep hole, 90...Lower seal block, 100...Upper seal block 110... Slit, 120, 130... Locking member, 140... Partition plate 150... Packaging material (packaging bag), 170... Inclined guide member 180... Steam guard, 180a... Horizontal surface portion 190... Auxiliary block, 200... Expansion mounting member, 200a... Guide hole 200b... Mounting piece, 210... Expansion detection member, 230... Expansion detection auxiliary member 300... Long heater wire, 310... Leaf spring, 320... Screw 500... Control device, 510... Vacuum pump, 520... Vacuum electromagnetic Valve 530...Soft solenoid valve, 540...Seal opening/closing solenoid valve (three-way valve)
550... Soft opening solenoid valve, 560... Vacuum opening solenoid valve, 600... Intake flow path 610... Seal closing drive flow path, 620... Closing cylinder

Claims (8)

During vacuum packaging, the opening of the packaging material containing the item to be packaged is sandwiched between upper and lower seal blocks provided in the chamber, and during the sealing process, electricity is applied to the heater wire to seal the sandwiched opening of the packaging material. A vacuum packaging machine that performs a preheating process before the sealing process. 2. The vacuum packaging machine according to claim 1, wherein the heater wire has a length capable of sealing a plurality of packaging materials at the same time, and is laid under tension on a lower side, an upper side, or an upper and lower sealing block. The vacuum packaging machine according to claim 1, wherein the preheating step reduces a temperature difference between the heater wires while the packaging material is being held. The vacuum packaging machine according to claim 1, wherein the temperature of the preheating step is automatically varied in accordance with the temperature of the sealing step. The vacuum packaging machine according to claim 1, wherein the time for energizing the heater wire in the preheating step is 0.6 seconds to 1 second. The vacuum packaging machine according to claim 5, wherein the energization time in the sealing step is a time corresponding to the temperature increased in the preheating step. 7. The vacuum packaging machine according to claim 1, wherein the heat generated in the preheating step is at a temperature at which the packaging material does not melt. chamber and
Upper and lower seal blocks provided in the chamber and sandwiching the opening of the packaging material containing the packaged item during vacuum packaging;
A heater wire laid under tension on the lower or upper side or upper and lower seal blocks;
a control means for energizing the heater wire during the sealing step to seal the opening of the sandwiched packaging material;
Equipped with
The vacuum packaging machine is characterized in that the control means energizes the heater wire to perform a preheating step before the sealing step in order to reduce a temperature difference between the heater wires while the packaging material is being held. .