JP6321342B2 - Deep drawing packaging machine - Google Patents

Description

  The present invention relates to a deep drawing packaging machine.

  As one of various packaging forms, there is a deep drawing type package. The deep-drawn type packaging body has a configuration including a container body having a recess for storing an object to be packaged, and a lid member for closing the opening of the container body in a state where the object to be packaged is stored in the recess. . A deep-drawing packaging machine for manufacturing a deep-drawn packaging body having such a configuration has the following configuration.

  The lower film continuously drawn from the raw fabric roll is conveyed in the horizontal direction. The lower film is vacuum-sucked by a molding device arranged in the middle of the conveyance, and a concave portion protruding downward is formed at a predetermined position of the lower film. Then, the article to be packaged is automatically or manually supplied into the recess at a predetermined position on the downstream side of the molding apparatus.

  On the other hand, another original fabric roll is installed above the lower film conveyance line, and the upper film is continuously drawn out from the original fabric roll. Is superimposed on the lower film at a predetermined position downstream of the supply point.

  Further, a sealing device is disposed downstream of the polymerization point of both films, and the sealing device seals the contact portion between the upper film and the lower film. Thereby, the article to be packaged is sealed in the recess. After that, the individual deep-drawn packagings are separately manufactured by cutting the sealing portions of both films with a cutter device disposed on the downstream side of the sealing device.

  A conventional molding apparatus has an upper box and a lower box that are arranged vertically with a lower film interposed therebetween. And the female type | mold processed into the internal shape corresponding to the external shape of the recessed part to shape | mold is arrange | positioned in a lower box. On the other hand, a plug that moves up and down relative to the upper box is provided in the upper box. This plug contacts the upper surface of the lower film and biases downward. Further, when the upper film and the lower box sandwich the lower film from above and below, the internal space of the upper box and the internal space of the lower box become separate closed spaces. Then, for example, the plug moves downward to push the lower film into the female mold. At this time, for example, compressed air is supplied into the upper box to increase the pressure, and the lower box is vacuumed to decrease the pressure. As a result, the lower film is in close contact with the inner peripheral surface of the female mold, and is molded into the shape of the inner peripheral surface, thereby forming a recess.

  Further, a heating plate is accommodated upstream of the female mold and the plug in each box, and the recess molding position of the lower film is preheated. By preheating in this way, the film portion at the concave molding position is heated and softened, and the concave section is smoothly molded by the next-stage female mold and plug.

  In the molding apparatus having such a configuration, first, the lower box moves up and sandwiches the lower film between the upper box and the lower box. Thereby, the film part which a pair of upper and lower heating plates oppose is heated. The heated film portion is positioned between the female mold and the plug in the “next” or “next next” cycle. Moreover, a heating plate is comprised from a flat plate. And by making the inside of a box into a compressed air state, the whole surface of a lower film is pressed on a heating plate, and it is trying to heat firmly. As such a conventional deep-drawing packaging machine, for example, there is an apparatus disclosed in Patent Document 1.

JP2002-145215

  Since the preheating of the lower film in the molding apparatus mounted on the conventional deep drawing packaging machine is performed in a compressed air state, intake / exhaust is performed with the lower film sandwiched between the upper box and the lower box. For this reason, the lower film cannot be fed during the intake and exhaust, which hinders shortening of the cycle type.

  Further, the lower film heated by the heating plate may be loosened. Such a loose film portion partially contacts the heating plate. Then, there is a possibility that the portion in contact with the heating plate is excessively heated and discolors, or temperature unevenness occurs in the film and wrinkles are generated.

  If the number of productions per unit time in the packaging machine is increased, the time during which the packaging machine is stopped intermittently is shortened. Then, it is impossible to preheat the film to a sufficient temperature in one preheat treatment, and it is necessary to preheat the same film part a plurality of times stepwise. Then, the film portion preheated in the previous stage is loosened, and the loosened film portion is sandwiched between the heating plates in the next stage, so that the above problem is more prominent.

In order to solve the above-described problems, the deep-drawing packaging machine of the present invention is (1) disposed on the downstream side of a molding apparatus that molds a recess with respect to the lower film that is intermittently conveyed. A means for covering the lower film in a state where an article to be packaged is inserted into the recess, and a seal for sealing the recess by sealing a predetermined portion of the upper film and the lower film. A deep-drawing packaging machine comprising a device and a cutting means for manufacturing individual packaging bodies by cutting predetermined portions of the upper film and the lower film, wherein the concave portion is provided upstream of the molding device. A preheating device that heats the molding region, and the preheating device includes a plurality of preheating portions in front and back along the conveying direction of the lower film, and a plurality of times for the same film portion in the plurality of preheating portions. Heat is applied, and among the plurality of preheated portions, at least the surface of the hot plate located on the most downstream side is swelled toward the lower film, and is swelled toward the lower film. The preheating part including a hot plate has a receiving part provided with a recess facing the surface of the swelled shape of the hot plate, and the receiving part has a peripheral wall part on the periphery of the recess, With the heat plate and the receiving portion sandwiching the lower film and the heat plate in contact with the lower film and preheating, the recess and the peripheral wall portion are not in contact with the lower film. .

  In such a configuration, the film part heated in the preheating part in the previous stage may be softened or stretched partially by the heat, but in the present invention, the preheating part located on the downstream side may be loosened. Wrinkles and slack are stretched by contacting the surface of the swelled hot plate in a state where the film portion is tight, and the hot plate is evenly contacted. Therefore, the lower film can be suppressed as much as possible from being heated uniformly and causing temperature unevenness. Furthermore, it suppresses that a part of lower film is heated too much, and suppresses generation | occurrence | production of discoloration.

  (2) It is good to have a plurality of said preheating parts provided with the bulging-shaped hot plate, and the hot plate of the several preheating part should enlarge a bulge on the downstream side. Heat the same film part of the lower film with a swelled hot plate in multiple preheating parts, and since the amount of swelling on the downstream side is large, the film that becomes more slack due to heat as it goes downstream becomes tight It can heat and can heat a film part more uniformly.

  (3) Of the plurality of preheating portions, at least the surface of the hot plate located on the most upstream side may be a flat surface. Since the film portion that has not been preheated is flat, no slack or the like is caused by heating. Therefore, by using a hot plate having a flat surface, preheating can be performed without applying excessive stress to the lower film. In the embodiment, the hot plates made of flat plates are arranged up and down, but a configuration of arranging only one of them may be adopted.

  (4) The plurality of preheating parts are provided in three, the surface of the hot plate of the first preheating part located on the upstream side is a flat surface, and the heat of the second preheating part located on the downstream side of the first preheating part The surface of the plate has a shape that bulges small toward the lower film, and the heat plate of the third preheating portion located on the downstream side of the second preheating portion has a shape that bulges greatly toward the lower film. Good.

  According to the present invention, the film can be preheated to a desired temperature by preheating the same film portion a plurality of times, even if the time during which the lower film is temporarily stopped is short. At that time, since the surface is in contact with the swelled hot plate, the film portion extends uniformly and the film portion can be heated uniformly.

It is a figure which shows one Embodiment of the deep drawing packaging machine which concerns on this invention. (A) is a top view which shows the lower film in which the recessed part was formed, (b) is a side view which shows the part of one recessed part. It is a front view which shows a 2nd preheating part and a 3rd preheating part. It is a side view which shows the principal part of a 2nd preheating part and a 3rd preheating part. It is an enlarged view which shows the principal part of a 2nd preheating part and a 3rd preheating part. It is a figure which shows a 2nd upper side heat plate, (a) is a top view, (b) is a side view, (c) is a front view. It is a figure which shows a lower side receiving plate, (a) is a top view, (b) is a side view, (c) is a front view.

  FIG. 1 shows an overall view of a preferred embodiment of a deep-drawing packaging machine according to the present invention. The deep drawing type packaging machine of this embodiment arrange | positions the lower film supply apparatus 1 in an upstream. The lower film supply device 1 conveys a belt-like lower film 2 continuously drawn out from a raw roll 2 'supported rotatably, over a plurality of rollers 1a, and transports the next film. Supplied to the transport device 3.

  Although not shown in the drawings, the film transport device 3 grips both side edges of the lower film 2 with nail members arranged at predetermined intervals of an endless chain provided between a pair of sprockets, and directly lowers the lower film. 2 is intermittently moved forward.

  A processing device or the like for performing each processing is provided at a predetermined position in the middle of transport of the film transport device 3. First, the preheating device 4 is arranged on the upstream side in the middle of conveyance. The preheating device 4 heats a predetermined part of the lower film 2. The detailed configuration of the preheating device 4 will be described later.

  A molding device 5 is disposed downstream of the preheating device. The molding device 5 molds a concave portion protruding downward in the film portion of the lower film 2 heated by the preheating device 4. In the present embodiment, for example, as shown in FIG. 2, a total of 15 concave portions 2 a are formed at a time in five rows and three rows in the front and rear. The concave portion 2a has an appropriate size, and the shape thereof is not a simple circle or ellipse, but a shape in which appropriate irregularities are provided on the side surface and the bottom surface.

  The molding apparatus 5 for molding such a shape includes an upper box 5a and a lower box 5b that are arranged vertically with a lower film interposed therebetween. And the female type | mold processed into the internal shape which corresponds to the external shape of the recessed part to shape | mold is arrange | positioned in the lower box 5b. On the other hand, the upper box 5a includes a plug that moves up and down relatively with respect to the upper box. This plug comes into contact with the upper surface of the lower film and biases downward, and a predetermined film portion of the lower film 2 is pushed into the lower box 5b to be positioned in the vicinity of the inner peripheral surface of the female mold. Subsequently, the inside of the lower box 5b is vacuum-sucked, and accordingly, the lower film 2 is brought into close contact with the inner peripheral surface of the female mold and is molded into the shape of the inner peripheral surface, thereby forming the recess 2a. Further, in this embodiment, the molding device 5 is not provided with a heating means such as a hot plate, and mechanical pressure by a plug, vacuum suction, etc. are applied to the film portion heated and softened by the preheating device 4. Although the recessed part 2a is formed by applying the air pressure, a heating means may be provided.

  An article supply device 6 is disposed at a predetermined position downstream of the molding device 5. The packaged article supply device 6 sequentially supplies the packaged articles into the recess 2a. In addition, it is good also as supply by hand instead of the to-be-packaged product supply apparatus 6. FIG.

  Further, an upper film supply device 7 is disposed at a substantially upper center portion of the conveyance path of the lower film 2. The upper film supply device 7 is provided with a raw roll 8 ′ that is rotatable, and covers the upper film 8 continuously drawn from the raw roll 8 ′ so as to cover the upper side of the lower film 2. Supply.

  Furthermore, a sealing device 9 is disposed in front of the coating point X of the upper film 8 in the traveling direction. The sealing device 9 heats and seals a predetermined position of the lower film 2 and the upper film 8, that is, sandwiches the contact portions of the two films 2 and 8 around the recess 2 a from above and below. Thereby, the article to be packaged is sealed in the recess 2a. The sealing device 9 is provided with a function of sucking and removing air in the recess, and the packaged object is vacuumed in the recess by sucking and removing the air in the recess before heat-sealing the films 2 and 8. It may be equipped with a function of sealing in a state, or the function of filling a predetermined gas is provided instead of the function of vacuuming and removing the inside of the recess to replace the inside of the recess with an inert gas such as nitrogen. You may make it do.

  A cutter device 10 is disposed in front of the sealing device 9 in the traveling direction. The cutter device 10 has a blade portion that follows the outer shape of each package, punches from above, holds each package manufactured by punching, and supplies it to the carry-out conveyor 11 below. Is provided. The film frame remaining after the package is punched is wound around the winding roller 12.

  Here, in this invention, as shown in FIG. 1, the preheating apparatus 4 is provided with the 1st preheating part 15, the 2nd preheating part 16, and the 3rd preheating part 17 which are arrange | positioned along a conveyance direction. And the 1st preheating part 15 located in the most upstream side is provided with the 1st upper side heat plate 15a and the 1st lower side heat plate 15b which were arrange | positioned up and down on both sides of the lower film 2. As shown in FIG. Both the first upper hot plate 15a and the first lower hot plate 15b move up and down to sandwich the lower film 2 from above and below. The first upper hot plate 15a and the first lower hot plate 15b have a flat surface facing the lower film 2. In practice, both are constructed using flat plates. Furthermore, the distance when the first upper hot plate 15a and the first lower hot plate 15b are closest to each other is set to be substantially equal to the thickness of the lower film 2. Thereby, at the timing when the lower film 2 conveyed by the film conveying device 3 is temporarily stopped, the first upper hot plate 15a and the first lower hot plate 15b move closer to each other, and the lower film 2 is moved. Even in the state of being sandwiched from above and below, it comes into a light contact or non-contact proximity state, and the lower film is heated and preheated without excessively pressing and crushing the lower film 2.

  The second preheating unit 16 and the third preheating unit 17 include a second upper heating plate 22 and a lower receiving plate 27 that are arranged vertically with the lower film 2 interposed therebetween. Both the second upper heat plate 22 and the lower receiving plate 27 can be moved up and down, and the lower film 2 is moved at the timing when the lower film 2 conveyed by the film conveying device 3 is temporarily stopped. Insert from above and below. And the concrete structure of the 2nd preheating part 16 and the 3rd preheating part 17 is as showing in FIGS.

  The first cylinder 21 is attached to the top plate of the machine frame 20 installed so as to surround the periphery of the film transport device 3. The cylinder rod 21a of the first cylinder 21 passes through the through hole 20a provided in the top plate of the machine frame 20, and can protrude downward. The cylinder rod 21 a is connected to the center of the upper surface of the support base plate 24. A guide rod 23 is erected at a predetermined position on the upper surface of the support base plate 24. The guide rod 23 is linked to a sliding bearing portion 30 provided in a vertically penetrating state on the top plate of the machine frame 20 so as to be capable of thrust movement. Thereby, with the reciprocation of the first cylinder 21, the support base plate 24 moves up and down while being guided by the guide rod 23 and the sliding bearing portion 30 and maintaining a stable horizontal state. The second upper heat plate 22 is attached to the lower surface of the support base plate 24.

  The second upper hot plate 22 includes a plurality of heating units 34 on the lower surface of the rectangular base 33. The heating unit 34 has a layout arranged at a site corresponding to the molding region of each recess 2a. Therefore, in the present embodiment, the heating unit 34 is provided in a total of 15 heating elements 34 in the front and rear three lines, and five in one horizontal line.

  Further, a heating element such as a heater is disposed in the base 33. The heating unit 34 is made of a material having good thermal conductivity such as aluminum. Therefore, the heat generated from the heating element is transmitted to the heating unit 34, and the surface temperature of the heating unit 34 increases. Further, the surface of the heating unit 34 is coated with Teflon (registered trademark) or the like. Thereby, even if the lower film 2 comes into contact with the surface of the heating unit 34, the lower film 2 separates smoothly without sticking due to fusion and adhesion.

  And the surface shape of the heating part 34 was made into the curved surface 34a which protrudes below. The central part of each heating part 34 swells most, and the amount of protrusion decreases as it goes to the periphery. In addition, the surface shape of the heating unit 34 has an arc shape with a relatively large predetermined radius of curvature as shown in FIG. 6 (b), and a short cross-section as shown in FIG. 6 (c). The cross section has a relatively large arc shape with a predetermined curvature radius. Further, the periphery of each heating unit 34 is a low step portion 34b that is one step lower and deeper than the curved surface 34a. The low step portion 34b is a flat surface cut out in a concave shape.

  Further, a side wall plate 35 protruding downward is attached to the long side of the lower surface of the base 33. The lower end position of the side wall plate 35 is lower than the lower step part 34b of the heating unit 34 and higher than the center vertex position of the curved surface 34a, as shown in an enlarged view in FIG. The side wall plates 35 are located on both the left and right sides in the traveling direction of the lower film 2.

  On the other hand, the second cylinder 26 is attached to the lower surface of the top plate of the support base 25 disposed below the film transport device 3. The cylinder rod 26 a of the second cylinder 26 penetrates through a through hole 25 a provided in the top plate of the support base 25 and can protrude upward. The cylinder rod 26 a is connected to the center of the lower surface of the support base plate 29. A guide rod 28 is suspended from a predetermined position on the lower surface of the support base plate 29. The guide rod 28 is linked to a sliding bearing 31 provided in a vertically penetrating state on the top surface of the support base 25 so as to be capable of thrust movement. Thus, as the second cylinder 26 reciprocates, the support base plate 29 moves up and down while being guided by the guide rod 28 and the sliding bearing portion 31 and maintaining a stable horizontal state. The lower receiving plate 27 is attached to the upper surface of the support base plate 29 via the support plate 36.

  The lower receiving plate 27 is configured by mounting a receiving portion 39 on the upper surface of a rectangular base 38. A recess 39 a is provided on the surface of the receiving portion 39 at a position facing the curved surface 34 a of each heating portion 34 of the second upper hot plate 22. And the surrounding wall part 39b is arrange | positioned at the periphery of the recess 39a. For example, as shown in FIG. 5, the dimension of the inner periphery of the recess 39a is set to be slightly wider than the dimension of the outer periphery of the curved surface 34a. Furthermore, as shown in FIG. 5, the peripheral wall portion 39 b is provided at a position facing the lower step portion 34 b of the heating unit 34 and the side wall plate 35. The height of the peripheral wall portion 39b is set so as not to contact the peripheral wall portion 39b and the low step portion 34b when the lower film 2 is sandwiched between the second upper heat plate 22 and the lower receiving plate 27. .

  The 2nd preheating part 16 and the 3rd preheating part 17 which consist of said structure operate | move as follows. That is, the film transport device 3 intermittently transports the lower film 2. Therefore, when the lower film 2 is temporarily stopped, the first cylinder 21 and the second cylinder 26 move forward, the second upper heat plate 22 moves downward, and the lower receiving plate 27 moves upward to approach each other. Moving. Then, the second upper heat plate 22 and the lower receiving plate 27 sandwich the lower film 2. At this time, as shown in FIG. 5, the heating unit 34 contacts the film portion of the lower film 2 facing and pushes downward, and the film portion from the center of the curved surface 34a to the appropriate position on the periphery is curved. Curve along the outer surface of the surface 34a. Further, since the side wall plate 35 / low step portion 34b provided on the second upper heat plate 22 and the peripheral wall portion 39b of the lower receiving plate 27 are not in contact with each other, the side wall plate 35 / low step portion 34b and the peripheral wall portion are not contacted. The film part of the lower film 2 located between 39b is not held there and can be moved. For this reason, for example, when a film portion biased downward by the curved surface 34a is to be deformed so as to protrude downward, the film portion is appropriately moved to be smoothly deformed. Furthermore, when the lower film 2 is deformed, the apex of the curved surface 34a first comes into contact with the lower film 2, and then the contact area gradually spreads to the periphery. Coupled with this, the lower film 2 can be stretched in a taut state without any wrinkles.

  That is, for example, assuming the processing in the second preheating unit 16, the film part heated in the first preheating unit 15 in the previous stage may be softened or stretched and partially slackened by the heat. is there. Such slackness of the film is stretched with the film portion coming into contact with the curved surface 34a of the second upper hot plate 22 of the second preheating portion 16, and uniformly on the hot plate (the curved surface 34a of the second upper hot plate 22). Contact. Therefore, the lower film 2 is heated uniformly and does not cause temperature unevenness. Furthermore, since there is no partial contact, a portion is not heated excessively, so that no discoloration occurs.

  In the present embodiment, the basic configurations of the second preheating unit 16 and the third preheating unit 17 are the same as shown in FIGS. The difference between the two makes the degree of swelling of the second upper hot plate 22 different. That is, the degree of swelling of the curved surface 34a of the heating unit 34 of the second upper heating plate 22 of the third preheating unit 17 is set to the degree of swelling of the curved surface 34a of the heating unit 34 of the second upper heating plate 22 of the second preheating unit 16. Bigger than. This may be adjusted, for example, by changing the radius of curvature of the curved surface 34a. By taking such a configuration, the film portion of the lower film 2 that has been preheated in the second preheating portion 16 is deformed into a slightly curved state by the curved surface 34a of the second preheating portion 16, and further the second preheating. The heat treatment in the part 16 further softens or loosens. Therefore, in the third preheating part 17 in the next step, the lower film 2 is preheated by the curved surface 34a of the heating part 34 having a large bulge, and therefore the third preheating part 17 is also similar to the second preheating part 16. Wrinkles and slack are stretched by contacting the curved surface 34a in a state where the film portion is tight, and uniformly contact the hot plate (curved surface 34a of the second upper hot plate 22). Therefore, the lower film 2 is heated uniformly and does not cause temperature unevenness. Furthermore, since there is no partial contact, a portion is not heated excessively, so that no discoloration occurs.

  In this way, since the film is preheated in three stages, the film portion corresponding to the recessed portion forming region is heated to a sufficient temperature and subjected to a forming process in the subsequent forming device 5 to form the recessed portion 2a. . Therefore, for example, in order to increase the number of production per unit time, even if the time during which the lower film 2 is temporarily stopped is shortened, it can be reliably preheated to a desired temperature. Furthermore, in this embodiment, the 1st preheating part 15, the 2nd preheating part 16, and the 3rd preheating part 17 which comprise the preheating apparatus 4 only heat a film mechanically using the heated hot plate. Since it is positioned in the box and is not compressed as in the prior art, the time required for intake and exhaust is not required, and the speed and productivity can be further improved.

  In the embodiment described above, the first preheating unit 15 uses a flat hot plate, and the second preheating unit 16 and the third preheating unit 17 are expanded (the amount of expansion is larger in the third preheating unit 17). Although used, the present invention is not limited to this, and the number of preheating units installed is arbitrary. Further, the first preheating portion 15 does not necessarily need to be provided with a flat hot plate, and a hot plate that swells from the first stage may be used. However, when a flat film portion is heated from the beginning with a swelled hot plate, the curved surface hits a film that has not been heated sufficiently and has not been softened. In view of this point, as in the above-described embodiment, the first stage is heated by using a flat hot plate, and the deflection caused by the heating is preferably heated by the hot plate having the second and subsequent bulges. .

  In the above-described embodiment, the second preheating unit 16 and the third preheating unit 17 both have a hot plate provided with a bulge on the upper side, but the installation position is arbitrary, and both or one of the preheating units is provided. A hot plate may be arranged on the lower side. Further, far-infrared rays may be used as a heat source instead of the hot plate.

Furthermore,
The shape of the curved surface of the hot plate having a bulge is not limited to that shown in the embodiment. For example, the central portion or the like has a flat surface, or the bulge is not a curved surface but a partially inclined surface. It may be like that.

  In the above-described embodiment, the example in which the time when the lower film is temporarily stopped is shortened and applied to the deep-drawing packaging machine in which productivity is improved has been described. However, the embodiment is not limited to the case where the pause time is shortened. .

2 Lower film 2a Concavity 4 Preheating device 5 Molding device 15 First preheating portion 15a First upper hot plate (flat plate)
15b First lower heat plate (flat plate)
16 2nd preheating part 17 3rd preheating part 22 2nd upper side heat plate 27 Lower side receiving plate 34 Heating part 34a Curved surface 34b Low step part 35 Side wall plate

Claims (4)

For the lower film that is intermittently conveyed, a molding device that molds the recess,
Means for covering the upper film with respect to the lower film, which is disposed downstream of the molding apparatus and in which the article to be packaged is inserted in the recess;
A sealing device for sealing the predetermined portion of the upper film and the lower film to seal the recess;
A deep-drawing packaging machine provided with a cutting means that cuts predetermined portions of the upper film and the lower film to produce individual packages,
A preheating device for heating the molding region of the recess on the upstream side of the molding device;
The preheating device is provided with a plurality of preheating parts in the front and rear along the conveyance direction of the lower film, and the same film part is preheated a plurality of times with the plurality of preheating parts,
Of the plurality of preheating parts, at least the surface of the hot plate located on the most downstream side is swelled toward the lower film,
The preheating part provided with a hot plate swelled toward the lower film has a receiving part provided with a recess facing the swelled shape of the hot plate,
The receiving portion has a peripheral wall portion on the periphery of the recess,
The recess and the peripheral wall portion are not in contact with the lower film in a state where the heat plate and the receiving portion are preheated with the heat plate in contact with the lower film with the lower film interposed therebetween. A deep-drawing packaging machine characterized by that. Having a plurality of the preheating parts provided with the swollen hot plate,
2. The deep-drawing packaging machine according to claim 1, wherein the hot plates of the plurality of preheating sections are swollen on the downstream side.   3. The deep-drawing packaging machine according to claim 1, wherein a surface of a hot plate located at least on the most upstream side of the plurality of preheating units is a flat surface. The plurality of preheating units includes three,
The surface of the hot plate of the first preheating part located on the upstream side is a flat surface,
The surface of the hot plate of the second preheating part located on the downstream side of the first preheating part has a shape bulging small toward the lower film,
The depth according to any one of claims 1 to 3, wherein the heat plate of the third preheating portion located on the downstream side of the second preheating portion has a shape that greatly bulges toward the lower film. Drawing wrapping machine.

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