Stretch film packaging method and stretch film packaging machine

Abstract

To provide a stretch film packaging method that can control air permeability without the use of fabricated films.SOLUTION: A stretch film packaging machine P comprises a carriage 4, a rotating mechanism 3 that rotates a multi-stacked item W to be packaged relative to the carriage, a lifting mechanism 5 that moves the carriage 4 up and down, and a controller 8 that controls each drive of the rotating mechanism 3 and the lifting mechanism 5. In a packaging method for wrapping a film F around the item W to be packaged using the packaging machine P, at least one of an upper edge and a lower edge of the film F is contracted in the vertical direction and wrapped around the item W to be packaged, so that a wrapping section 9 and a non-wrapping section 10 are provided.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a stretch film packaging method and a stretch film packaging machine for wrapping and packaging a plurality of parcels loaded on a pallet while stretching a plastic film. [Background technology]

[0002] Conventionally, in stretch film packaging, tension corresponding to the packaged items is applied to the stretch film and it is wrapped around the outer periphery of the packaged items to prevent the packaged items stacked in multiple layers from collapsing during transport.

[0003] Known methods of wrapping film include film packaging, in which stretch film is pulled out and wrapped around the outer periphery of the packaged item, and rope packaging, in which the width of the stretch film is contracted to a string-like shape and wrapped around the outer periphery.

[0004] The packaged items include vegetables, fruits, and other fresh produce, which secrete ethylene gas to promote ripening. Ethylene gas is necessary for the ripening of fresh produce, but as they ripen, they become overripe and prone to deterioration and decay, so they need to release ethylene gas. Furthermore, since fresh produce continues to breathe even after harvest, they need to release moisture (water vapor) and be supplied with oxygen, necessitating a packaging method that allows for breathability. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Utility Model Application Publication No. 52-44183 [Patent Document 2] Patent No. 7127611 Summary of the Invention [Problem to be solved by the invention]

[0006] With film packaging, the entire periphery of the packaged item is covered, resulting in low breathability and leading to deterioration of the fruit and vegetables, while with rope packaging, the entire periphery of the packaged item is not covered, resulting in high breathability, but if the string-like film shifts position due to load during transportation, the packaged item can no longer be secured, resulting in the load collapsing. Also, if the tightening torque is increased to prevent the film from shifting, this can lead to damage to the packaged item, so it has been necessary to change the packaging conditions depending on the size and material of the packaged item.

[0007] To improve the breathability of film packaging, perforated films have been proposed, as in Patent Documents 1 and 2. However, applying a certain amount of force to the film during packaging can cause deformation at the perforations, potentially resulting in film tearing. This requires time and effort to change settings such as tension and speed during winding for each film, depending on the film's characteristics. Furthermore, because some packaged items are adversely affected by high breathability, it is necessary to prepare films tailored to the intended use.

[0008] The stretch film packaging method and packaging machine of the present invention provide a packaging method and packaging machine that can ensure breathability depending on the item to be packaged without changing the film. [Means for solving the problem]

[0009] The stretch film packaging method of the present invention is a packaging method using a packaging machine that includes a carriage from which film is unwound, a rotation mechanism that rotates the packaged items stacked in multiple layers relative to the carriage, a lifting mechanism that moves the carriage up and down, and a controller that controls the drive of the rotation mechanism and the lifting mechanism, and unwinds film onto the packaged items while rotating the packaged items relative to the carriage, and raises and lowers the carriage to wrap the film around the packaged items, and at least one of the upper and lower edges of the film is contracted in the vertical direction to provide a wrapped section and a non-wrapped section on the packaged items around which the film is wrapped.

[0010] In addition, the stretch film packaging machine of the present invention comprises a carriage from which film is unwound, a rotation mechanism that rotates the packaged items stacked in multiple layers relative to the carriage, a lifting mechanism that moves the carriage up and down, and a controller that controls the driving of the rotation mechanism and the lifting mechanism, and unwinds film onto the packaged items while rotating the packaged items relative to the carriage, and wraps the film around the packaged items by raising and lowering the carriage, and the carriage is equipped with a film width changing mechanism that shrinks at least one of the upper and lower edges of the film in the vertical direction.

[0011] In the stretch film packaging method of the present invention, at least one of the upper and lower edges of the film may be shrunk in the vertical direction, and a thick portion may be formed in at least one of the upper and lower edges.

[0012] In addition, in the stretch film packaging method of the present invention, the lowest packaged item placed on the rotating mechanism may be packaged with film in which only one of the upper and lower edges has been shrunk in the vertical direction, and the middle to upper portions of the packaged item may be packaged with film in which the upper and lower edges have been shrunk in the vertical direction. [Effects of the Invention]

[0013] According to the present invention, the width of the film can be controlled by shrinking at least one of the upper and lower edges of the film in the vertical direction, and even under the same film packaging conditions, the packaged item wrapped in the film can have a packaged portion and a non-packaged portion, thereby ensuring breathability without creating holes in the film.

[0014] If the bottommost packaged item placed on the rotating mechanism is wrapped in film with only one of the upper and lower edges shrunk in the vertical direction, and the middle to upper portions of the packaged items are wrapped in film with the upper and lower edges shrunk in the vertical direction, the bottommost packaged item can be wrapped with the films tightly pressed together to prevent the film from unraveling, and the middle to upper portions can be wrapped securely by providing a non-wrapped section.

[0015] If at least one of the upper and lower edges of the film is shrunk in the vertical direction and a thick portion is formed on at least one of the upper and lower edges, the film will have a thick portion on at least one of the upper and lower edges due to the shrinkage.The thick portion will act as a rope wrap and can firmly hold the packaged item, while the non-thick portion will act as film wrapping and will adhere to the packaged item in a suitable width in the vertical direction, preventing problems that can occur with rope wrapping, such as the rope-like film getting caught between stacked packaged items. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is an explanatory diagram showing an example of a packaging form in a packaging method according to the present invention. [Figure 2] 2 is a front view showing the beginning of winding in the packaging form of FIG. 1. FIG. [Figure 3] 2 is a front view showing the state when the carriage reaches the top in the packaging form of FIG. 1. FIG. [Figure 4] FIG. 2 is a front view showing the final winding state in the packaging form of FIG. [Figure 5] FIG. 10 is a front view showing an example of the start of winding in a packaging form with no non-packaging portion. [Figure 6] FIG. 10 is a front view showing an example of a final winding state in a packaging form with no non-packaging portion. [Figure 7] FIG. 2 is an explanatory diagram showing the configuration of a film width changing mechanism according to the present invention. [Figure 8] 10A and 10B are explanatory diagrams illustrating the state of the film according to the film width changing mechanism of the present invention. [Figure 9] FIG. 2 is a plan view schematically showing the configuration of a film feeding device. DETAILED DESCRIPTION OF THE INVENTION

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to the accompanying drawings. An example of a packaging form in the packaging method according to the present invention is shown in Figure 1. The bottom layer of the packaged items W stacked vertically in multiple layers is wrapped with film F with only the upper edge shrunk vertically, and the middle to upper layers are wrapped with film F with the upper and lower edges shrunk vertically.

[0018] 2 to 4 show an example of the packaging configuration shown in Fig. 1. The stretch film packaging machine P (hereinafter sometimes simply referred to as packaging machine P) according to the present invention is a turntable-type packaging machine, and is mainly composed of a base frame 1, a mast 2 to which the lower end of the base frame 1 is fixed, a turntable 3 on which packaged items W are placed in width and depth directions (not shown) and stacked vertically, a carriage 4 for unwinding film F (stretch film), an elevating mechanism 5 for vertically moving carriage 4, a film width changing mechanism 6 for changing the width of the film, a film unwinding device 7 for unwinding film F toward packaged items W, and a controller 8 for controlling the driving of each of the turntable 3 and the elevating mechanism 5 as a rotation mechanism. A pressure plate may be installed on the top of mast 2 to prevent packaged items W placed on turntable 3 from collapsing when they are rotated.

[0019] As shown in FIGS. 2 to 4 , the end of film F is fixed near the bottom of the stack of packaged items W, and the upper edge of film F is vertically contracted by film upper edge restricting portion 61, and then film F is wrapped around the bottom of the packaged items W several times. After wrapping, film lower edge restricting portion 62 is operated to vertically contract the lower edge of film F, while carriage 4 is raised to a set height by lifting mechanism 5 while unwinding film F. After reaching the set height, carriage 4 is lowered to the initial height while maintaining the distance between upper and lower edge restricting portions 61, 62. Just before reaching the initial height, the contraction caused by film lower edge restricting portion 62 is relaxed, and upon reaching the initial height, the contracted state is released. The above packaging configuration is one example; packaging may be performed by contracting the lower edge by film lower edge restricting portion 62 and controlling the contraction of film upper edge restricting portion 61. Any packaging method is possible as long as at least one of the upper and lower edges of film F is contracted.

[0020] As a result, even under the same film wrapping conditions, such as the speed at which the film F is wrapped around the packaged item W, i.e., the rotation speed of the turntable 3 and the lifting speed of the lifting mechanism 5, the vertical width dimension of the film F can be changed simply by controlling the film width regulating mechanism 6. Therefore, it is possible to provide a gap between adjacent vertical sections of film F wrapped around the packaged item W, and by providing a wrapping section 9 and a non-wrapping section 10 on the packaged item W around which film F is wrapped, the ratio of the wrapping section 9 to the non-wrapping section 10 can be freely changed. Note that the packaging method and packaging machine P according to the present invention do not mean that the film wrapping conditions are not changed during packaging, and the film wrapping conditions may be changed as appropriate.

[0021] The film width can be controlled simply by controlling the film width regulating mechanism 6, and even under the same film packaging conditions, the packaged item wrapped with the film can have a packaged section and a non-packaged section. Therefore, the breathability can be controlled simply by changing the film width depending on the contents of the packaged item, eliminating the need to change the film to suit the application. Note that the packaging method and packaging machine P according to the present invention do not mean that the film cannot be changed, and the type of film may be changed as appropriate.

[0022] 5 and 6 are explanatory diagrams showing a packaging form without a non-wrapping section 10 in the stretch film packaging machine P according to the present invention. By fixing the regulated width of the film width changing mechanism 6 and packaging, a packaging form without a non-wrapping section 10 can be implemented with a shrinkable section on at least one of the upper and lower edges of the film F.

[0023] If the size of the packaged item W is the same, the winding position of the film F is determined by the lifting speed of the film F, which is set by the lifting mechanism 5, and the rotation speed of the turntable 3. Therefore, by simply controlling the width with the film width changing mechanism 6, it is possible to control the proportion of the unwrapped portion 10 of the packaged item W, between a state in which adjacent films F wrapped around the packaged item W partially overlap with no gaps, and a state in which gaps are left between the films F, that is, to control the proportion of the unwrapped portion 10 of the packaged item W, and package the packaged item W according to its contents without changing the film F or packaging conditions.

[0024] FIG. 7 shows the configuration of the film width changing mechanism 6, with (a) being a front view and (b) being a side view. An upper film edge regulating unit 61 and a lower film edge regulating unit 62 are attached to a movable auxiliary lane 63, and the positions of the upper and lower regulating units 61, 62 can be changed depending on the setting. This allows the vertical width of the film F to be changed as it passes between the upper film edge regulating unit 61 and the lower film edge regulating unit 62. In the film width changing mechanism 6, the upper film edge regulating unit 61 and the lower film edge mechanism 62 are provided on the same movable auxiliary lane 63, but the upper film edge regulating unit 61 and the lower film edge mechanism 62 may be provided on different movable auxiliary lanes 63 as long as the film width can be changed.

[0025] FIG. 8 schematically illustrates the state of the film F after the film width changing mechanism 6 is applied, with (a) showing the non-shrinkage state and (b) showing the shrinkage state. The amount of shrinkage of the film F can be controlled by the height position of the film upper edge regulating portion 61. The shrinkage state shown in FIG. 8 is an example, and the film F may be shrunk toward one side. Furthermore, the film F may be shrunk into a roll shape instead of a folded shape. The shrinkage state may take any shape as long as a thick portion 11 can be formed in the thickness direction of the film F on at least one of the upper and lower edges of the film F. While FIG. 8 illustrates the relationship between the film upper edge regulating portion 61 and the film F, the relationship between the film lower edge regulating portion 62 and the film F can also be in a similar configuration, inverted vertically in FIG. 8. Therefore, the thick portion 11 can be formed by vertically shrinking both the upper and lower ends of the film F.

[0026] The film unwinding device 7 is mounted on the carriage 4 and includes three rollers, a unwinding roller 71, a stretching roller 72, and a guide roller 73, as well as the film width changing mechanism 6, and the guide roller 73 is rotatable. The unwinding roller 71 and the stretching roller 72 are each provided with rotational force from a different motor, and by controlling the rotation speed of the unwinding roller 71 and the stretching roller 72, that is, by making the rotation speed of the stretching roller 72 relatively faster, the film F can be unwound in a pre-stretched state.

[0027] This makes it possible to reduce the amount of film F used. Generally, film F can be stretched by increasing the rotation speed of turntable 3 relative to the payout speed of film F paid out from film payout device 7, but in this case, excessive load is applied to packaged item W, and, for example, if a cardboard box is used for packaged item W, there is a risk that the cardboard box may be partially dented or damaged. Furthermore, although film F is stretched, its dimensions in the width and thickness directions become smaller, so although the amount of film F used can be reduced, the reduction effect is also reduced by the smaller dimension in the width direction.

[0028] According to this embodiment, the thickness of the film F decreases during stretching, but the degree to which the width dimension decreases is relatively suppressed compared to when the rotation speed of the turntable 3 is increased. In order to apply tension to the film F, the rotation speed of the turntable 3 must be made slightly faster than the payout speed of the film F, but the rotation speed of the turntable does not need to be increased so much that the paid-out film F is further stretched. Therefore, when cardboard is used for the packaged goods W as described above, it is possible to suppress problems such as damage to the cardboard, and further, the amount of film F used can be reduced.

[0029] In the film unwinding device 7, as shown in Figure 9, the film F is passed from the film roll R between the unwinding roller 71, the stretching roller 72, and the guide roller 73, and then unwound from the unwinding roller 71 through the guide roller 73 toward the side of the packaged item W on the turntable 3.

[0030] In the film unwinding device 7, the film width changing mechanism 6 is disposed between the stretching roller 72 and the guide roller 73. In a stretched state by the stretching roller 72 and the guide roller 73, at least one of the upper and lower edges of the film F can be contracted in the vertical direction to form the thick portion 11, while the uncontracted portion can maintain the film shape.

[0031] As a result, the packaging procedure generally involves starting wrapping from the bottom layer of stacked packaged items W, wrapping from the middle to the top, then returning from the middle to the bottom layer, and finishing by adhering the film F together at the bottom layer. Therefore, it is necessary to prevent the wrapped film F from unraveling, especially at the bottom layer. Here, near the thick portion 11, which is near the compressed portion, the compressed portion comes into contact with the stacked film F when stacked in the thickness direction, but the uncompressed portion may float and not come into contact, potentially resulting in insufficient adhesion. On the other hand, since there is no compressed portion on the opposite side of the film F in the vertical direction, the film F is simply stacked, resulting in sufficient adhesion between the films F. Depending on the shape of the packaged items W and the width of the film F, the film F wrapped around the bottom layer of the packaged items W in Figure 4 may not have compressed portions at the top and bottom edges. [Explanation of symbols]

[0032] 1 base frame 2 Mast 3. Turntable 4 carriages 5 Lifting mechanism 6 Film width change mechanism 61 Film upper edge regulation part 62 Film lower edge regulation part 63 Movable auxiliary lane 7 Film feeding device 71 Feed roller 72 Stretching roller 73 Guide roller 8 Controllers 9 Packaging Department 10 Packaged part 11 Thick part F film P packaging machine R film roll W Packaged item

Claims

1. A packaging method using a packaging machine comprising a carriage from which film is unwound, a rotation mechanism that rotates the packaged items stacked in multiple layers relative to the carriage, a lifting mechanism that moves the carriage up and down, and a controller that controls the drive of the rotation mechanism and the lifting mechanism, in which the film is unwound onto the packaged items while rotating the packaged items relative to the carriage, and the carriage is raised and lowered to wrap the film around the packaged items, and in which at least one of the upper and lower edges of the film is contracted in the vertical direction to create a wrapped section and a non-wrapped section on the packaged items around which the film is wrapped.

2. 2. The stretch film packaging method according to claim 1, wherein at least one of the upper and lower edges of the film is shrunk vertically to form a thickened portion at least on the upper and lower edges.

3. The stretch film packaging method of claim 1, wherein the lowest packaged item placed on the rotating mechanism is packaged with film in which only one of the upper and lower edges has been shrunk in the vertical direction, and the middle to upper portions of the packaged item are packaged with film in which the upper and lower edges have been shrunk in the vertical direction.

4. A packaging machine comprising a carriage from which film is unwound, a rotation mechanism that rotates the packaged items stacked in multiple layers relative to the carriage, a lifting mechanism that moves the carriage up and down, and a controller that controls the driving of the rotation mechanism and the lifting mechanism, wherein the packaging machine unwinds film onto the packaged items while rotating the packaged items relative to the carriage and wraps the film around the packaged items by raising and lowering the carriage, and the carriage is provided with a film width changing mechanism that shrinks at least one of the upper and lower edges of the film in the vertical direction.

Images