JP3942918B2 - Packaging equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a packaging device, in particular, a packaging device that folds a peripheral portion of a film covering an object to be packaged to the bottom side of the object to be packaged and heat-seals the overlapped part, and heat seals by changing the object It is related with the packaging apparatus from which the thickness of the overlap part of the film which performs is changed.
[0002]
[Prior art]
A so-called stretch wrapping apparatus is widely known as an apparatus for covering and sealing an object to be packaged such as fruits and vegetables or food on a tray with a film. In this stretch wrapping device, the packaged object is pushed up against the tension-held film, the peripheral part of the film covering the packaged object is folded to the bottom side of the packaged object, and the package is heat-sealed. Package with film.
[0003]
An example of such a stretch wrapping apparatus is disclosed in Japanese Patent No. 2727953. Here, the peripheral part of the film is folded to the bottom side of the product by the front and rear folding plates arranged before and after the packaging part, and heat sealing is performed by applying heat while sandwiching the overlapping part of the film between the front and rear members.
[0004]
[Problems to be solved by the invention]
In the stretch wrapping apparatus as described above, the peripheral part of the film is folded under the package from the left and right front and back, so that the peripheral part of the film is folded on the bottom side of the package. At the time of heat sealing, the folded film is sandwiched between two front and rear members, and pressure and heat are applied.
[0005]
However, when a lot of films are folded on the heat-sealed portion, there is a possibility that a sealing failure may occur in a portion where the overlapped films are very thick. In particular, when a package of various sizes must be packaged while using a film of a certain size as a packaging material, there is a difference in the amount of film that folds on the bottom side of the package at the time of each packaging. When many films are overlapped, there is a possibility that the heat seal is not sufficiently performed.
[0006]
An object of the present invention is a packaging device that performs heat sealing by folding a peripheral portion of a film to the bottom side of an object to be packaged, and the thickness of an overlapping portion of the film that performs heat sealing changes as the object to be packaged changes. It is to suppress the occurrence of defective sealing in the packaging device.
[0007]
[Means for Solving the Problems]
The packaging apparatus according to claim 1 is a packaging apparatus that folds the peripheral portion of the film covering the packaged object to the bottom side of the packaged object, and heat-seals the overlapped part. It is the packaging apparatus from which the thickness of the overlapping part of the film which performs is changed. The packaging device includes first and second members, driving means, and a control unit. The first and second members sandwich the overlapping portions of the films that perform heat sealing. The driving means applies pressure to the overlapping portion of the film via the first and second members. A control part controls a drive means based on the relative magnitude | size of a film and a to-be-packaged object, and adjusts the pressure applied to the overlapping part of a film.
[0008]
Here, the overlapping part of the peripheral part of the film folded into the bottom side of the package is sandwiched between the first and second members and heat-sealed by applying pressure. And the drive means which applies a pressure to the overlapping part of a film is controlled by the control part, and the pressure added to the overlapping part of a film is adjusted based on the characteristic of a package. Therefore, the film thickness of the overlapping portion of the film folded on the bottom side of the package object is preliminarily estimated based on characteristics such as the size and shape of the package object, and the thickness of the folded film and the characteristics of the package object are preliminarily estimated. If the pressure required for heat sealing is determined based on the correlation between the pressure and the pressure in the heat sealing can be brought close to the appropriate one according to the film thickness by controlling the drive means appropriately. Become.
[0009]
In other words, the thickness of the film to be overlapped on the bottom side of the package can be predicted to some extent depending on characteristics such as the size and shape of the package, and there is a certain relationship between the film thickness and the pressure required for heat sealing. Therefore, it is possible to determine the pressure required for heat sealing based on the characteristics of the packaged object. In view of this, in the present invention, control for adjusting the pressure applied to the overlapping portion of the film is performed based on the characteristics of the object to be packaged, thereby suppressing heat seal defects. Thereby, even when a film having a certain size is used as a packaging material and an object to be packaged of various sizes has to be packaged, the occurrence of poor sealing is reduced.
[0010]
The packaging device according to claim 2 is the packaging device according to claim 1, wherein the control unit calculates the thickness of the film in the overlapping portion of the film from the relative size of the film and the object to be packaged, The driving means is controlled based on the thickness.
[0011]
The packaging device according to claim 3 is the packaging device according to claim 1 or 2 , wherein the control unit has a smaller size of the packaged object when the size of the film covering the packaged item is the same. Accordingly, the pressure applied to the overlapping portions of the film is increased stepwise or continuously.
[0012]
If the size of the film covering the package is the same, as the size of the package decreases, the amount of the film that is folded and overlapped on the bottom side of the package increases, and the heat sealing film overlaps. There is a tendency for the thickness to increase.
[0013]
In view of this, in the packaging device of the present invention, the driving means is controlled so that the pressure applied to the overlapping portion of the film increases stepwise or continuously as the size of the packaged object decreases. . By controlling in this way, even when the object to be packaged becomes smaller and the thickness of the overlapping film on the bottom side of the object to be packaged becomes thicker, the pressure at the time of heat sealing increases and the occurrence of poor sealing is suppressed.
[0014]
In particular, when packaging fruits and vegetables such as vegetables and fruits without using a tray, the size of the article to be packaged often changes, and the effect of suppressing the occurrence of defective seals by using the packaging device of the present invention works effectively. It will be.
[0015]
A packaging device according to a fourth aspect is the packaging device according to any one of the first to third aspects , wherein the drive means has a motor for pressing the first member against the second member. And a control part controls the voltage or electric current supplied to a motor, and adjusts the pressure added to the overlapping part of a film.
[0016]
Here, pressure is applied to the overlapping portion of the film via the first and second members by the driving force of the motor, and pressure adjustment is performed by controlling the voltage or current supplied to the motor. The motor may be a DC motor or an AC motor, and a servo motor capable of inverter control may be used.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
<Overall configuration and general operation>
A schematic side view, front view, and plan view of a stretch wrapping apparatus according to an embodiment of the present invention are shown in FIGS. Moreover, the control block of the stretch wrapping apparatus 10 is shown in FIG. The stretch wrapping device 10 is a small weighing and packaging device, and is designed to wrap fruits and vegetables with note trays or to wrap foods (products) such as fruits and vegetables contained in soft trays. However, even a product placed on a normal foam tray (hard tray) can be packaged.
[0018]
The stretch wrapping apparatus 10 has a weighing function and a pricing function (a label creation function including a measurement value and a price), but here, the description will be made focusing on the wrapping function of the stretch wrapping apparatus 10.
[0019]
The stretch wrapping device 10 is a device in which each mechanism is attached to the main body frame 15, and mainly includes a product introduction mechanism 20, a lift mechanism 30, a film transport mechanism 40, a film holding mechanism 50, and a film pushing mechanism. 60, a fill arm left right turn write mechanism 66, and a heat sealing and the film before and after the folding mechanism 70.
[0020]
When the product G (see the product G on the front side in FIG. 1) is placed on the introduction table 21 of the product introduction mechanism 20 by the operator's hand, the product G is measured after the product G is weighed by the measuring instrument 29. It is sent to the lift mechanism 30 (see the product G on the rear side of FIG. 1). On the other hand, the film F transported above the lift mechanism 30 by the film transport mechanism 40 is pre-stretched in a state where the front and rear, right and left ends are gripped by the film holding mechanism 50 (see FIG. 10B). When the product G supported by the lift mechanism 30 is pushed up with respect to the pre-stretched film F, the product G is in a state where the upper side and the side are covered with the film F with the film F pushed up (see FIG. 10 (c)).
[0021]
Thus, the peripheral part of the film F covering the upper side and the side of the product G is folded to the bottom side of the product G by the left and right pushing members 61 and 62 and the rear folding plate 71 (see FIG. 10E). Before this folding operation, the left and right folding plates 64 and 65 enter the vicinity of the left and right ends of the bottom of the product G and play a role of supporting the bottom of the product G together with the lift mechanism 30. The film F folded on the bottom side of the product G receives heat input from the nichrome wire 81 attached to the front fixing member 72 while being sandwiched between the rear folding plate 71 and the front fixing member 72. Then, heat sealing is performed (see FIG. 13D).
[0022]
The product G thus wrapped with the film F including the heat seal is taken out by the operator's hand, and the surplus film hanging from the bottom surface (see the surplus film F1 in FIG. 18) is placed on the bottom surface of the packaged product G. The label is attached by being patted and discharged from a pricing mechanism (not shown). The stroking operation is performed in such a manner that the operator lightly presses the surplus film and the bottom surface of the product G against the heater attached to the stretch wrapping apparatus 10 or separately provided.
[0023]
<Composition of product introduction mechanism 20>
As shown in FIGS. 1 and 4, the merchandise introduction mechanism 20 mainly includes an introduction table 21, an introduction table vertical movement motor 22, and an introduction table longitudinal movement motor 23. The introduction table 21 supports the product G by a plurality of support plates 21a arranged in the left-right direction. These support plates 21a and support members 34a, 34b, 35a (described later) of the lift mechanism 30 shown in FIG. A measuring instrument 29 for measuring the weight of the commodity G placed on the introduction table 21 is disposed below the introduction table 21. The introduction table 21 is connected to an introduction table longitudinal movement motor 23 via a belt, a pulley, or the like, and moves back and forth by the operation of the introduction table longitudinal movement motor 23. Further, the entire longitudinal movement unit including the introduction table 21 and the introduction table longitudinal movement motor 23 is configured to move up and down by the introduction table vertical movement motor 22.
[0024]
When each motor 22 and 23 of the product introduction mechanism 20 is actuated by a command from the control unit 90 to be described later, the introduction table 21 performs a rectangular motion, and the product G placed on the introduction table 21 by the walking beam method is moved to the rear side. It is sent onto the support members 34a, 34b, 35a of the lift mechanism 30.
[0025]
<Configuration of lift mechanism 30>
The lift mechanism 30 is provided to support the bottom of the product G sent from the product introduction mechanism 20 and lift the product G upward. Further, the lift mechanism 30 plays a role of supporting the bottom of the product G even when the peripheral portion of the film F is folded to the bottom side of the product G, as will be described later.
[0026]
As shown in FIGS. 1, 2, 4 and 5, the lift mechanism 30 mainly includes a vertical rail 30a arranged on the left and right sides, a slider 31a that moves up and down along the vertical rail 30a, and a link mechanism 30c. The lift motor 30d moves the slider 31a up and down via the link mechanism 30c, the first base 31 mounted on the slider 31a, and the small rail 31b extending downward from the upper center of the first base 31 up and down. And a second base 32 that moves. The lift mechanism 30 includes a regression mechanism and a time difference descending solenoid switch 37.
[0027]
The link mechanism 30c rotates around the pin support portion 30b by the operation of the lift motor 30d, and moves the slider 31a and the first base 31 up and down along the vertical rail 30a.
[0028]
[First base 31]
As shown in FIGS. 5 and 7, the first base 31 is formed integrally with the slider 31a, and includes a left and right support member 34a and a central front and rear support member 34b. The first base 31 has a left and right divided portion, and a support member 34a (or 34b) extends upward from each divided portion one by one. In the left and right support members 34a, the upper surface that supports the product G is a horizontal plane, and three each are arranged on the left and right. Each of the left and right support members 34a has a structure in which the upper part can be collapsed inward. When the left and right folding plates 64 and 65 and the left and right pushing members 61 and 62, which will be described later, come in, the left and right folding plates 64 and 65 are provided. It falls inward by the force that acts from etc. On the other hand, the center front / rear support member 34b extends upward from the center of the first base 31 divided into seven parts, and does not fall down. The center front and rear support member 34b plays a role of supporting a central portion in the left-right direction of the product G together with the center support member 35a described later, but forms a concave shape in a side view combined with the center support member 35a. Is stably supported (see FIG. 5A). The center front / rear support member 34b supports a front portion and a rear portion of the center portion of the product G in the left-right direction.
[0029]
The two small rails 31 b extend downward from the upper center of the first base 31. The small rail 31b is provided to vertically move the left and right support members 34a and the center front / rear support member 34b fixed to the first base 31 and the center support member 35a pin-supported by the second base 32. Yes.
[0030]
[Second base 32]
The second base 32 has a slide portion 32a, which is a rear portion, engaged with the small rail 31b so as to be slidable up and down. Therefore, the second base 32 can move up and down relatively with respect to the first base 31. The lower ends of the two small rails 31b are connected by a member for preventing the slide portion 32a of the second base 32 from falling off the small rail 31b. A stopper bolt is attached to a member connecting the lower ends of the two small rails 31b, and the head of the bolt supports the lower surface of the slide portion 32a of the second base 32 from below. For this reason, when the slider 31a and the 1st base 31 raise, the 2nd base 32 will also raise.
[0031]
The second base 32 supports the central support member 35a by four link bars 35b. The center support member 35a is two plate-like members for supporting the center portion of the bottom of the product G. As shown in FIG. 5, the upper surface of the central support member 35a is concave in a side view. The upper part of the link bar 35 b is pin-bonded to the central support member 35 a, and the lower part is pin-bonded to the second base 32. These link bars 35 b serve to move the central support member 35 a back and forth by a predetermined distance with respect to the second base 32. That is, the central support member 35a is configured to move back and forth within a predetermined range with respect to the second base 32 fixed in the front-rear direction (see FIGS. 5B and 5C).
[0032]
An extension member 32b extends downward from the rear end of the slide portion 32a of the second base 32. The lower end of the extension member 32b is bent backward to form a horizontal portion 32c. The horizontal portion 32c is supported from below by a shaft 37a of a solenoid switch 37 described later when the peripheral portion of the film F is folded to the bottom side of the product G (see FIG. 5A).
[0033]
[Regression mechanism]
The return mechanism of the lift mechanism 30 includes a structure in which the second base 32 supports the central support member 35a so as to be movable back and forth via the link bar 35b, and a guide roller 36a provided at the front end of the first base 31. The The guide roller 36a is rotatably supported at the front end of the first base 31, and hits the center of the front link bar 35b so that the center support member 35a does not move forward more than necessary. It plays a role of regulating movement (see FIG. 5C). Further, the guide roller 36a serves to guide the central support member 35a so as to return backward when the first base 31 is lowered first and the second base 32 is lowered later.
[0034]
When the second base 32 descends after the first base 31 descends first, a backward reaction force (reaction force against the downward inertia force of the central support member 35a) from the guide roller 36a to the front link bar 35b. Works. For example, in the state shown in FIG. 6A, a backward force acts on the link bar 35b from the guide roller 36a. Thereby, the center supporting member 35a returns to the original position backward (see FIG. 6B).
[0035]
Note that the stopper 32d works when the central support member 35a returns to the original front-rear position so that the central support member 35a does not move rearward more than necessary. The stopper 32d is provided at the front end of the second base 32, and prevents excessive rearward movement of the central support member 35a by restricting forward movement of the lower end of the rear link bar 35b.
[0036]
[Solenoid switch 37 for time difference lowering]
The time difference descending solenoid switch 37 of the lift mechanism 30 is fixed to the main body frame 15. The solenoid switch 37 operates immediately after the first and second bases 31 and 32 are raised to the highest point, and the shaft 37a supports the lower surface of the horizontal portion 32c of the second base 32 from the lower side (FIG. 5 ( a)). Thereby, even if the 1st base 31 descend | falls as shown in FIG.5 (b), the 2nd base 32 maintains the same height position until the solenoid switch 37 is turned off.
[0037]
<Configuration of film transport mechanism 40>
The film transport mechanism 40 is a mechanism for transporting the film F cut to a predetermined size above the product G supported by the lift mechanism 30 and holding the film F in tension. The film transport mechanism 40 mainly moves the roll holding part 41 that rotatably supports the film roll R, the front clamp 54 that holds the front end of the film F fed from the film roll R, and the front clamp 54 to move back and forth. And a front clamp moving mechanism. The front clamp moving mechanism includes a front clamp forward / backward movement motor 56a (see FIG. 4), a belt mechanism, a front clamp support member, and the like. Here, the front clamp 54 moves back and forth by operating the front clamp forward / backward movement motor 56a. The front clamp 54 grips or separates the front end portion of the film F by turning on / off the front clamp solenoid switch 56b shown in FIG.
[0038]
When a command to convey the film F is issued from the control unit 90, the front side clamp 54 moves rearward and grasps the leading end of the film F that is fed from the film roll R and reaches the vicinity of the rear side clamp 53. Then, the front clamp 54 moves forward with the front end of the film F being gripped, so that the film F is positioned above the lift mechanism 30.
[0039]
<Configuration of Film Holding Mechanism 50>
The film holding mechanism 50 mainly includes a front clamp 54 and a front clamp moving mechanism, which are also components of the film transport mechanism 40, a rear clamp 53 and a rear clamp moving mechanism, a left clamp 51, a right clamp 52, and a later-described film. It is comprised from the left-right pushing member moving mechanism which is also a component of the film pushing mechanism 60 to perform.
[0040]
The rear clamp 53 grips and separates the rear end of the film F by turning on and off the rear clamp solenoid switch 55b shown in FIG. 4, and moves back and forth by the rear clamp moving mechanism. The rear clamp movement mechanism includes a rear clamp forward / backward movement motor 55a (see FIG. 4), a belt mechanism, a rear clamp support member, and the like.
[0041]
As shown in FIG. 9, the left clamp 51 and the right clamp 52 are provided below left and right pressing members 61 and 62, which will be described later, and the film F is sandwiched between the left and right pressing members 61 and 62. Grip. That is, the left clamp 51 and the right clamp 52 move upward to grip the film F by contacting the left and right pushing members 61, 62, and move downward to leave the film F by moving away from the left and right pushing members 61, 62. Release the grip. Therefore, in order to move the left clamp 51 and the right clamp 52 up and down, as shown in FIG. 4, a left clamp up-and-down motor 51a and a right clamp up-and-down motor 52a are provided. When the left clamp vertical movement motor 51a and the right clamp vertical movement motor 52a operate, the left clamp support base 51b and the right clamp support base 52b that support the left clamp 51 and the right clamp 52 move up and down.
[0042]
The left clamp 51 and the right clamp 52 are supported by a left clamp support base 51b and a right clamp support base 52b so as to be movable left and right by a predetermined distance. Then, the left clamp 51 and the right clamp 52 can slightly move up and down with respect to the left clamp support base 51b and the right clamp support base 52b so that the left clamp 51 and the right clamp 52 do not draw an arcuate locus due to the left-right movement. It is configured as follows. Therefore, when the left and right push members 61 and 62 move to the left and right in a state where the left clamp 51 and the right clamp 52 are pressed against the left and right push members 61 and 62 from below, the left clamp 51 and the right clamp 52 follow the movement. . In other words, the left and right pushing member moving mechanism that moves the left and right pushing members 61 and 62 to the left and right also serves to move the left clamp 51 and the right clamp 52 to the left and right.
[0043]
The film holding mechanism 50 plays a role of gripping the peripheral portion of the film F when the product G is pushed up by the lift mechanism 30 and is in a state where the film F is stretched immediately before the product G is pushed up. Perform a pre-stretch operation. By this pre-stretching operation, the clamps 53, 54, 51, 52 holding the peripheral portion of the film F are horizontally moved outward, and the film F is stretched by a predetermined amount.
[0044]
<Configuration of film push-in mechanism 60>
The film pushing mechanism 60 includes left and right pushing members 61 and 62 and a left and right pushing member moving mechanism that moves the pushing members 61 and 62 to the left and right. The left and right pushing member moving mechanism includes a film pushing motor 63a shown in FIG. 4, a belt mechanism, a support member that supports the left and right pushing members 61 and 62, and the like. The film pushing motor 63a is operated by a command from the control unit 90, and moves the left and right pushing members 61 and 62 to the left and right.
[0045]
Further, the left and right pushing members 61 and 62 can grip the film F by sandwiching the film F between the left clamp 51 and the right clamp 52, and act as a part of the clamp. The left and right pushing members 61 and 62 are formed with long holes for strengthening the clamping action. Since the same applies to any of the pressing members 61 and 62, here, the elongated hole 61a formed in the left pressing member 61 shown in FIG. 9B will be described. The long hole 61 a is formed long in the front-rear direction, and has a size such that a protruding portion 51 c protruding upward from the upper surface of the left clamp 51 can be inserted. When the left clamp 51 moves upward and comes into close contact with the pushing member 61, the protrusion 51c of the left clamp 51 enters the long hole 61a, and the film F enters between the protrusion 51c and the long hole 61a. The movement of F in the left-right direction is strongly restricted. Thus, the presence of the protrusion 51c and the long hole 61a enhances the degree of gripping the film F by the clamp 51 and the pushing member 61.
[0046]
<Configuration of film left / right folding mechanism 66>
The film right / left folding mechanism 66 mainly includes left and right folding plates 64 and 65 and a left / right folding motor 68a (see FIG. 4) for moving the left and right folding plates 64 and 65 to the left and right. . The left and right folding motor 68a moves the folding plates 64 and 65 to the left and right via a belt mechanism, a support member that supports the folding plates 64 and 65, and the like.
[0047]
The left and right folding plates 64 and 65 are disposed above the left and right pushing members 61 and 62 and support the bottom of the product G during the film folding operation by the rear folding plate 71 described later.
[0048]
<Configuration of Heat Sealing / Film Front and Back Folding Mechanism 70>
The heat sealing and film front / rear folding mechanism 70 operates after the right and left ends of the film F covering the product G are folded under the product G, and the rear end of the film F is folded under the product G. This is a mechanism for sandwiching the film F under the product G and heat-sealing.
[0049]
The mechanism 70 mainly includes a rear folding plate 71 and a rear folding plate moving mechanism, a rear clamp 53 and a rear clamp moving mechanism (described above), a front fixing member 72, a front clamp 54 and a front clamp moving mechanism (described above). ) And a nichrome wire 81 and a thermistor 82 attached to the front fixing member 72.
[0050]
The rear folding plate 71 is disposed between the left and right pushing members 61 and 62 and the left and right folding plates 64 and 65 in the height direction, and folds the film F from the back to the bottom side of the product G and fixes the front side. The film F is sandwiched between the member 72 and a pressing force necessary for heat sealing is applied to the film F. The rear folding plate moving mechanism includes a rear folding plate moving motor 71a (see FIG. 4), a belt mechanism, a support member that supports the rear folding plate, and the like. When the rear folding plate moving motor 71a is actuated by a command from the control unit 90, the rear folding plate 71 moves back and forth.
[0051]
The rear folding plate 71 has a pressing portion that presses against the front fixing member 72 on the front surface of the main body 71b. As shown in FIG. 3 and FIG. 8A, the pressing portion includes a protruding portion 71c, upper and lower pressing portions 71d and 71f, and elastic portions 71e and 71g. On the other hand, the front side fixing member 72 is fixed to the main body frame 15 and includes an aluminum plate 72 a, upper and lower stainless steel plates 72 b and 72 c, and a nichrome wire 81. The nichrome wire 81 is attached to the rear surface of the aluminum plate 72a via an insulating tape, and is located at a position retracted to the front side from the rear surfaces of the stainless plates 72b and 72c. As shown in FIG. 8A, the nichrome wire 81 and the aluminum plate 72a are opposed to the protruding portion 71c. The stainless plates 72b and 72c are mounted on the upper and lower sides of the aluminum plate 72a, and the rear surfaces thereof are opposed to the pressing portions 71d and 71f.
[0052]
The upper and lower pressing portions of the rear folding plate 71 are disposed above and below the projecting portion 71c and supported by the main body 71b through the elastic portions 71e and 71g so as to be movable back and forth. The elastic portions 71e and 71g are rubbers that shrink more than the longitudinal distance between the rear surface of the nichrome wire 81 and the rear surfaces of the stainless steel plates 72b and 72c, and a plurality of elastic portions 71e and 71g are provided in the left-right direction.
[0053]
A bakelite member is attached to the tip of the protrusion 71 c of the rear folding plate 71. The bakelite member is made of a material having suitable hardness, heat resistance, wear resistance, insulation, and the like.
[0054]
A thermistor 82 is embedded in the aluminum plate 72 a of the front fixing member 72. The thermistor 82 is provided to estimate the amount of heat applied to the film F from the nichrome wire 81, measures the temperature of the aluminum plate 72a, and sends it to the controller 90.
[0055]
A fixing roller 73 is disposed below the front fixing member 72 as shown in FIG.
[0056]
<Details of operation of stretch wrapping apparatus 10>
Next, of the operations of the stretch wrapping apparatus 10, the operation of folding the film F from the left and right to the bottom side of the product G and the operation of folding the film F from the rear to the bottom side of the product G and heat-sealing the film F are detailed. Explained.
[0057]
(Left / right folding and pushing)
As shown in FIG. 10A, when the film F is transported above the lift mechanism 30 by the film transport mechanism 40, the left and right clamps 51, 52 are lifted up and between the left and right pushing members 61, 62. To grip the left and right portions of the film F. At this time, the front and rear portions of the film F are also held by the front and rear clamps 53 and 54.
[0058]
The plane position of the film F is determined by the movement of the film transport mechanism 40 and the film holding mechanism 50. The plane position of the film F depends on characteristics such as the type and size of the product G and the presence / absence of a tray. Accordingly, control is performed by the control unit 90. The control relating to the adjustment of the planar position of the film F will be described in detail later.
[0059]
Next, the left and right pushing members 61 and 62 and the left and right clamps 51 and 52 following them are opened outward, and the film F is pre-stretched in the left and right direction (see FIG. 10B). At this time, the film F is also prestretched in the front-rear direction.
[0060]
In this way, the lift mechanism 30 raises the product G placed on the support members 34a, 34b, and 35a with respect to the film F that has been pre-stretched and has no wrinkles, and creates a state in which the film F is pushed up by the product G ( (Refer FIG.10 (c)). At this time, the product G is in a state where the film F is covered upward by the film F with the film F pushed up.
[0061]
As shown in FIG. 10 (c), when the product G is in a state of pushing up the film F, the left and right folding plates 64 and 65 enter the inner side first, and the left and right pushing members 61 and 62 and The rear folding plate 71 also enters inside. The left and right folding plates 64 and 65 stop moving when they enter the inside to a position where the bottom of the product G can be supported. On the other hand, the left and right push-in members 61 and 62 and the left and right clamps 51 and 52 that follow the left and right push-in members 64 and 65 prevent the excessive tension from acting on the film F due to the movement of the left and right folding plates 64 and 65. Then, the left and right clamps 51 and 52 are lowered at an appropriate position to release the right and left portions of the film F (see FIG. 10D).
[0062]
Even after releasing the grip of the left and right portions of the film F, the left and right pushing members 61 and 62 continue to move inward to push the film F into the bottom side of the product G, and finally from the left and right folding plates 64 and 65. It moves to the inside and stops (see FIG. 10 (e)). FIG. 11 shows the positional relationship between the left and right folding plates 64 and 65 and the left and right pushing members 61 and 62, and the rear folding plate 71 and the front side fixing member 72 in plan view.
[0063]
In the above-described left and right folding operation, the product G is supported by the lift mechanism 30 in principle by the central front and rear support members 34b and 35a, and the left and right support plates 34a are supported by the left and right folding plates 64. , 65 to replace the support. When the left and right folding plates 64 and 65 enter the inside, the left and right support members 34a are pushed by the left and right folding plates 64 and 65 in order from the outside, and fall inward.
[0064]
[Post-folding operation and heat sealing operation]
The product G and the film F that are in the state shown in FIG. 10 (e) or FIG. 11 by the above left and right folding operation and pushing operation are in the state shown in FIG. 12 (a) in a side view. In the rear folding operation, the rear folding plate 71 first moves forward, and the rear clamp 53 moves forward with a slight delay. Thereafter, the rear clamp 53 moves forward in accordance with the movement of the rear folding plate 71 so that excessive tension does not act on the film F (see FIG. 12B).
[0065]
Then, when the rear folding plate 71 approaches the lift mechanism 30, the first base 31 is lowered, and the support of the product G by the central front and rear support member 34b is released (see FIG. 12C). At this time, the first base 31 is lowered by the lift motor 30d, but the time difference lowering solenoid switch 37 is maintained as it is, so that the second base 32 remains at the same height without being lowered. Therefore, for a while after the first base 31 is lowered, the product G is supported by the central support member 35a supported by the second base 32 and the left and right folding plates 64 and 65.
[0066]
When the rear folding plate 71 further moves forward and hits the central support member 35a of the lift mechanism 30, it is pushed forward by the force from the rear folding plate 71 and the central support member 35a begins to move forward (FIG. 12D). )reference). Following this, the product G also starts moving forward. Further, as the central support member 35a and the product G move forward, the front clamp 54 moves forward in order to keep the tension of the film F on the front side of the product G properly (see FIG. 12D). . FIG. 14 shows a plan view of the rear folding plate 71 and the like when the central support member 35a moves forward while supporting the product G.
[0067]
When the central support member 35a of the lift mechanism 30 and the product G approach the front fixing member 72, the shaft 37a of the time difference descending solenoid switch 37 is retracted, and the second base 32 and the central support member 35a are lowered (FIG. 5 ( c), FIG. 6 (a), and FIG. 6 (b)). As a result, there is no obstruction of the rear folding plate 71 and the rear clamp 53 below the product G, and the rear folding plate 71 and the rear clamp 53 move further forward (FIG. 13B, ( c)). Also at this time, the product G that receives a forward force from the rear folding plate 71 via the film F slides on the left and right folding plates 64 and 65 and continues to move forward.
[0068]
Finally, the rear folding plate 71 hits the front fixing member 72, specifically, the protrusion 71c of the rear folding plate 71 hits the nichrome wire 81 of the front fixing member 72, and the front film F and the rear side The film F is heat-sealed under the product G by the pressing force and heat input from the nichrome wire 81 (see FIG. 13D). When the heat sealing process is performed, the front film F and the rear film F are sandwiched and held between the stainless plates 72b and 72c and the pressing portions 71d and 71f above and below the heat seal portion. The As a result, the influence of film tension, such as the portion covering the product G in the portions held by the stainless steel plates 72b and 72c and the holding portions 71d and 71f, is blocked, and the heat seal is expected in the vicinity of the heat seal portion. The trouble that the tension which does not act on the film breaks the film is avoided.
[0069]
Note that the grip of the film F by the rear clamp 53 and the front clamp 54 is released at the time of heat input from the nichrome wire 81 or just before that. This also suppresses changes in the tension of the film F during heat input.
[0070]
Thereafter, the rear folding plate 71 and the rear clamp 53 return to the rear, and the product G covered with the film F and heat-sealed is supported by the front portions of the left and right folding plates 64 and 65. Become. This packaged product G is taken out by the operator's hand, and a surplus film (see surplus film F1 in FIG. 18) that hangs down from the bottom is stroked on the bottom.
[0071]
<Configuration of Control Unit 90 and Characteristic Control by Control Unit 90>
The control unit 90 controls the operation of each mechanism 20, 30, 40, 50, 60, 66, 70 of the stretch wrapping apparatus 10. The control unit 90 includes a storage unit 91 such as a RAM.
[0072]
The storage unit 91 stores information about the product G and information about the film F collected by external input, manual input, or input from the measuring instrument 29 or the like.
[0073]
[A: Control related to film front / rear position adjustment]
The control unit 90 controls the film transport mechanism 40 and the film holding mechanism 50, and specifically includes a front clamp forward / backward movement motor 56a that moves the front clamp 54 and a rear clamp forward / backward movement motor 55a that moves the rear clamp 53. By controlling, the plane position (front-rear position) of the film F can be adjusted. On the other hand, as shown in FIG. 1, the vertical rail 30 a of the lift mechanism 30 is fixed, and the push-up position (planar front-rear position) of the product G by the lift mechanism 30 cannot be moved.
[0074]
That is, the push-up position of the product G is fixed, but the control unit 90 can adjust the relative plane position of the film F with respect to the push-up position of the product G.
[0075]
And the control part 90 changes the relative plane position of the film F with respect to the product G pushed up according to the characteristic of the product G, and the product G is packaged appropriately.
[0076]
Specifically, when the product G is placed on a soft soft tray, the control is performed so that the center of the film F substantially coincides with the center of the product G to be pushed up. By controlling in this way, the load applied to the soft tray is reduced and the soft tray is not easily crushed. In addition, when the product G is a round vegetable, the control is performed so that the center of the film F substantially coincides with the center of the product G to be pushed up. By controlling in this way, the film F can be prevented from slacking during the packaging operation, and the entire fruit and vegetables can be covered with the film F even when the size of the fruit and vegetables is large. On the other hand, when the product G is placed on a hard tray, control is performed so that the center of the product G pushed up from the center of the film F is positioned on the discharge side (front side). By controlling in this way, the film F is stretched strongly, and the packaged product G is finished with a better appearance.
[0077]
It should be noted that information such as what kind of tray the product G is placed on and what the product G is without a tray, along with characteristics such as the item name and size of the product G, Prestored in the storage unit 91. The control unit 90 controls the film transport mechanism 40 and the film holding mechanism 50 based on the product information manually or automatically input to the storage unit 91 and adjusts the planar position of the film F.
[0078]
[B: Control regarding left and right folding operation and pushing operation]
(B-1)
The control unit 90 controls the film pushing motor 63a and the left and right folding motor 68a based on the control data including the property information of the product G and the film F in the storage unit 91, and the left and right pushing members 61, 62 and The movement amount and the movement timing of the left and right folding plates 64 and 65 are optimal for the product G and the film F. Control data includes data relating to whether or not the product G includes a tray, data relating to the shape of the product G or tray, data relating to the dimensions of the product G or tray, data relating to the rigidity of the product G or tray, and data relating to the size of the film F. Data, and data on the type of film F, etc., but here, film size, film type, tray depth / width / height, tray softness, product G shape (round, etc.), product Control data including information on the height of G, whether the product G is placed on a hard tray or a soft tray, or whether the product G is packaged without a tray is used.
[0079]
The timing for releasing the right and left portions of the film F in the left and right folding operation, that is, the timing for lowering the left and right clamps 51 and 52 is also controlled based on the above control data.
[0080]
(B-2)
As shown in FIG. 5A, the central front and rear support member 34b has a concave shape in a side view combined with the central support member 35a so that the product G such as fruits and vegetables can be stably supported. In the detailed operation of the stretch wrapping apparatus 10 described above, the description and illustration are made on the assumption that the product G has a round bottom such as fruits and vegetables. However, if the product G is in the tray T, Depending on the size, as shown in FIG. 15A, the tray T is supported only by the central front and rear support member 34b, and a gap H (see FIG. 15B) is formed between the bottom surface of the tray T and the central support member 35a. ) May occur.
[0081]
Such a gap H occurs when the rear folding plate 71 approaches the lift mechanism 30, the first base 31 is lowered, and the support of the product G by the central front and rear support member 34b is released (see FIG. 12C). ), The film F covering the tray T may be loosened.
[0082]
On the other hand, since the product information including the information on the tray T is stored in the storage unit 91 of the control unit 90, the control unit 90 can recognize the occurrence of the gap H.
[0083]
For this reason, in the stretch wrapping device 10, the film F covering the tray T does not loosen even when the first base 31 of the lift mechanism 30 is lowered and the support of the product G by the central front and rear support member 34 b is released. As described above, the control unit 90 performs an additional folding operation. This additional folding operation is performed when it is assumed that the gap H shown in FIG. 15B is generated from the product information in the storage unit 91. From the state of FIG. When 34b descends and shifts to the state of FIG. 16B, the left and right folding plates 64 and 65 are moved further inward. In this way, by moving the left and right folding plates 64 and 65 further inward, it is possible to maintain the tension of the film F that should be loosened when the tray T has dropped by the gap H at the same level as before. it can.
[0084]
[C: Control for rear folding operation]
(C-1)
The control unit 90 controls the rear folding plate moving motor 71a, the rear clamp forward / backward movement motor 55a, and the front clamp forward / backward movement motor 56a based on the property information of the product G and the film F in the storage unit 91. Specifically, the rear clamp forward / backward movement motor 55a that moves the rear clamp 53 in accordance with the movement of the rear folding plate 71 by the rear folding plate moving motor 71a is controlled so that excessive tension does not act on the film F. In order to keep the tension of the front film F that changes due to the forward movement of the product G in an appropriate range, the front clamp forward / backward movement motor 56a that moves the front clamp 54 is controlled. Accordingly, the rear clamp 53 and the front clamp 54 shown in FIG. 12C and FIG. 12D are moved forward, the tension of the film F is maintained, and wrinkles due to the looseness of the film F are maintained. Occurrence etc. will be suppressed. Further, excessive tension acts on the film F to prevent the film F from being perforated or excessive force from acting on the product G.
[0085]
(C-2)
When the product G is not on a tray such as fruit and vegetables, as shown in FIG. 13, the surplus film that hangs from the bottom of the packaged product G will hang from the bottom center of the product G. Is desirable. When the shape of the product G such as fruits and vegetables is round, it is easier to maintain the tension of the film F appropriately by heat sealing near the center of the bottom of the product G. This is because there is little slack. Therefore, when the shape of the product G such as fruits and vegetables is round, the movement of the front clamp 54 is controlled so that heat sealing is performed near the center of the bottom of the product G.
[0086]
On the other hand, when the bottom surface of the product G is flat or nearly flat, specifically, the product G is in a tray T or a plurality of fruits and vegetables (for example, cucumbers and eggplants) are arranged in a plane. When it is, it is often desirable to offset the position of the heat seal back and forth from the center of the product G for the following reasons. In particular, considering the discharge direction and the work efficiency when the surplus film of the product G after packaging is applied to the bottom surface, it is desirable to offset the position of the heat seal to the front side of the center of the product G.
[0087]
FIG. 17A shows a state (a state corresponding to FIG. 13C) immediately before heat sealing in the case where the commodity is placed on the tray T. From here, by adjusting the movement of the front clamp 54, it is possible to adjust which part of the bottom surface of the tray T is to be heat-sealed.
[0088]
When the front clamp 54 is controlled not to move or slightly rearward from the state shown in FIG. 17 (a), as shown in FIG. 17 (b-1), below the front side portion of the bottom surface of the tray T. Film F is heat sealed. In this case, as shown in FIG. 18 (a), the surplus film F1 hangs down from the front portion of the bottom surface of the tray T. The excess film F1 can be folded and applied to the rear side of the bottom surface of the tray T while being taken out. This operation (patching operation) does not go against the take-out direction, and the operator can naturally apply the surplus film to the bottom surface of the tray T. Moreover, although it depends on the setting position (front / rear position) of the film F described later, it is easy to avoid the surplus film applied to the bottom surface of the tray T from protruding from the bottom surface of the tray T.
[0089]
When the front clamp 54 is moved to the rear side from the state shown in FIG. 17A, the film F heats below the center portion of the bottom surface of the tray T as shown in FIG. Sealed. In this case, as shown in FIG. 18B, the surplus film F1 hangs down from the central portion of the bottom surface of the tray T, the packaged tray T is taken out and the surplus film F1 is stroked on the bottom surface of the tray T. If attached, the leading end of the surplus film F1 often protrudes from the bottom surface of the tray T. Therefore, the control in which the surplus film F1 hangs down from the central portion of the bottom surface of the tray T as shown in FIG.
[0090]
When the front clamp 54 is moved largely rearward from the state shown in FIG. 17A, the film F is heat-sealed below the rear portion of the bottom surface of the tray T as shown in FIG. 17B-3. The In this case, as shown in FIG. 18 (c), the surplus film F1 hangs down from the rear portion of the bottom surface of the tray T. The surplus film F1 must be folded to the front side of the bottom surface of the tray T while being taken out to the side.
This operation (stroking operation) is counter to the take-out direction, and the workability is often deteriorated for the operator. On the other hand, although it depends on the setting position of the film F, which will be described later, it can be said that it is easy to avoid the surplus film applied to the bottom surface of the tray T from protruding from the bottom surface of the tray T. Therefore, depending on the position of a heater (not shown) for stroking the surplus film F1 on the bottom surface of the tray T, this control may be the most convenient for the packaged tray T as shown in FIG. 17 (b-3). Since there exists a merit which becomes pushed out to the front side and becomes easy to take out, it may become preferable control rather than performing a heat seal in the position shown in FIG.17 (b-1).
[0091]
Next, with reference to FIG. 19 and FIG. 20, the preferable heat seal position and the front-rear position adjustment of the film will be considered with specific dimensions.
[0092]
First, the film transport mechanism 40 and the film holding mechanism 50 are controlled so that the front and back center of the tray T, which is a product to be pushed up, and the front and back centers of the film F having a length of 500 mm held by the front and rear clamps 53 and 54 coincide with each other. Consider the case (see FIG. 19A). The dimensions of the tray T in a side view are as shown in FIG. In this case, if the front clamp 54 or the like is controlled so that the heat seal position is in the center of the tray T, the surplus film F1 after packaging hanging from the center of the bottom surface of the tray T is 80 mm in both the front and rear sides (FIG. 20 (a- 1)). Therefore, when the surplus film F1 is stroked on the bottom surface of the tray T, the leading end 25 mm of the surplus film F1 protrudes from the peripheral edge of the bottom surface of the tray T. Further, when the front clamp 54 or the like is controlled so that the heat seal position is located at one of the front and rear ends of the tray T, the surplus film F1 after packaging hanging from the bottom end of the tray T becomes 135 mm and 25 mm (see FIG. 20 (a-2)). Therefore, when the surplus film F1 is stroked on the bottom surface of the tray T, the leading end 25 mm of the surplus film F1 protrudes from the peripheral edge of the bottom surface of the tray T. That is, with such dimensions, when the front-rear center of the tray T and the front-rear center of the film F are made to coincide with each other, the leading end of the surplus film F1 protrudes from the bottom surface of the tray T regardless of the heat seal position.
[0093]
Next, the film transport mechanism 40 and the film holding unit are offset so that the front and rear center of the tray T, which is a product to be pushed up, and the front and rear center of the film F having a length of 500 mm held by the front and rear clamps 53 and 54 are offset by 55 mm. Consider the case where the mechanism 50 is controlled (see FIG. 19B). In this case, when the front side clamp 54 and the like are controlled so that the heat seal position is at the center of the tray T, the surplus film F1 after packaging hanging from the center of the bottom surface of the tray T becomes 135 mm and 25 mm (FIG. 20 (b- 1)). Therefore, when the surplus film F1 is stroked on the bottom surface of the tray T, the leading end 80 mm of the surplus film F1 protrudes from the peripheral edge of the bottom surface of the tray T. On the other hand, when the front clamp 54 or the like is controlled so that the heat seal position is at either the front or rear end of the tray T, the surplus film F1 after packaging hanging from the bottom end of the tray T is 80 mm both front and rear (FIG. 20). (Refer to (b-2)). Accordingly, when the surplus film F1 is stroked on the bottom surface of the tray T, the entire surplus film F1 is accommodated on the bottom surface of the tray T without the tip of the surplus film F1 protruding from the peripheral edge of the bottom surface of the tray T.
[0094]
From the above consideration, in the dimensional relationship shown in FIG. 19, it is appropriate to control so that the front and rear center of the tray T and the front and rear center of the film F are offset and the heat seal position is at the front and rear ends of the tray T. It can be said that. However, in FIG. 20A-2, since the front and rear lengths of the film F are relatively long with respect to the size of the tray T, the leading edge of the surplus film F1 slightly protrudes from the bottom surface of the tray T, but does not protrude. If it is such a dimensional relationship, it can be said that it is desirable to perform packaging in a state as shown in FIG. This is because, after the surplus film F1 is applied to the bottom surface of the tray T, the uniformity of the overlapping film F on the bottom surface of the tray T is improved, and the adhesion and appearance of the film F on the bottom surface of the tray T are improved.
[0095]
As described above, the amount of offset between the front and rear center of the tray T and the front and rear center of the film F and the position of the heat seal are controlled by the size of the film F, the presence or absence of the tray T, the shape and size of the product (the shape of the tray T In addition to the conditions including the size), the optimum control differs depending on the setting conditions of each other. Control related to the adjustment of the front and rear positions of the film F and the adjustment of the heat seal position by the control unit 90 is appropriate considering such various conditions.
[0096]
[D: Control related to heat sealing operation]
(D-1)
When the front film F and the rear film F are sandwiched between the rear folding plate 71 and the front fixing member 72 below the product G, the control unit 90 has a large voltage or current (impulse) that lasts for a very short time. Is applied to the film F by flowing it through the nichrome wire 81. That is, here, an impulse seal that can change the amount of heat input to the heat seal portion with high responsiveness is employed.
[0097]
Then, the control unit 90 determines at least one of the current value, voltage value, number of times, and energization time of the impulse flowing through the nichrome wire 81 based on the temperature measured by the thermistor 82 embedded in the aluminum plate 72a of the front fixing member 72. To change. For this reason, the film F can be heat-sealed with an amount of heat input that is not excessive or insufficient.
[0098]
For example, when the temperature of the front fixing member 72 rises or falls due to a change in the surrounding environment, the temperature change is measured by the thermistor 82, so the nichrome wire 81 is controlled so that heat sealing is performed appropriately. be able to. Specifically, when the ambient temperature is low in winter, the temperature of the aluminum plate 72a is lowered, and the amount of heat necessary for heat sealing may be insufficient. Therefore, the impulse sealing is controlled to compensate for this.
[0099]
(D-2)
In the stretch wrapping apparatus 10 described above, the peripheral portion of the film F is folded from the left and right front and back to the bottom side of the product G. Therefore, as shown in FIGS. It will be in a folded state. Although the folding state varies depending on the sizes of the film F and the product G, if these conditions are known, the folding state can be generally predicted. For example, it is predicted with high probability whether four films will be folded as shown in FIG. 21 (a) or whether six to eight films will be folded as shown in FIG. 21 (b). Is possible.
[0100]
In view of this, the control unit 90 of the stretch wrapping apparatus 10 determines the film F during heat sealing based on characteristics such as the size of the film F and the shape and size of the product G (including the characteristics of the tray if a tray is provided). The pressure applied to is controlled. Specifically, the pressure for pressing the rear folding plate 71 against the front fixing member 72 is controlled by adjusting the current value or voltage value of the rear folding plate moving motor 71a.
[0101]
When the size of the product G is relatively large with respect to the size of the film F and the number of folded sheets of the heat-sealed film is expected to be small, the control unit 90 moves the rear folding plate 71 to the front side. The rear folding plate moving motor 71a is controlled so that the pressure pressed against the fixing member 72 becomes relatively small. When the size of the product G is relatively small with respect to the size of the film F and the number of folded sheets of the heat-sealed film is expected to increase, the control unit 90 moves the rear folding plate 71 to the front side. The rear folding plate moving motor 71a is controlled so that the pressure pressed against the fixing member 72 becomes relatively large.
[0102]
<Position alignment of left and right clamps 51 and 52 before operation>
Here, the left and right clamps 51 and 52 are configured to move to the left and right following the left and right movement of the left and right pushing members 61 and 62. However, a drive mechanism that can independently move the left and right clamps 51 and 52 to the left and right is as follows. Not deployed.
[0103]
On the other hand, the applicant of the present application finds that it is desirable to appropriately determine the initial positions of the left and right clamps 51 and 52 based on the left and right width W3 of the film F and the left and right width W1 of the product G (see FIG. 9A). Have gained. In particular, when the width W3 of the film F is long and the width W1 of the product G is short, if the left and right clamps 51 and 52 are not arranged at appropriate initial positions, a sufficient prestretch amount cannot be secured in the left and right direction. The distance that the left and right clamps 51 and 52 must move to obtain the necessary pre-stretch amount may increase.
[0104]
In view of this, in the stretch wrapping apparatus 10, the distance W2 between the left and right clamps 51 and 52 (see FIG. 9A) is an appropriate value with respect to the width W3 of the film F and the width W1 of the product G. A method is adopted in which the operator determines the initial positions of the left and right clamps 51 and 52 in the left-right direction.
[0105]
Specifically, in the portion where the left clamp support base 51b and the right clamp support base 52b are fixed to the main body frame 15 in the left-right direction below, several steps are provided in the left-right direction, and the width W3 of the film F is set. In addition, the operator determines the fixed position using a table in the operation manual in which the fixed position can be derived from the width W1 of the product G. Therefore, when the width W3 of the film F or the width W1 of the product G changes, the fixing position for fixing the left clamp support base 51b and the right clamp support base 52b in the left-right direction changes, as indicated by an arrow A in FIG. The left and right positions of the left clamp support base 51b and the right clamp support base 52b change.
[0106]
<Characteristics of stretch wrapping device 10>
(1)
In the stretch wrapping apparatus 10, the relative plane position of the film F covering the product (or tray) with respect to the product changes according to the product by the control of the film transport mechanism 40 and the film holding mechanism 50 by the control unit 90. That is, the plane position of the film F is determined so that the relationship between the plane position of the film F and the plane position of the product is appropriate for the product. Therefore, an operator who works using the stretch wrapping apparatus 10 simply does not recognize that the appropriate positional relationship between the film F and the product differs depending on the product, and simply introduces the introduction base 21 of the product introduction mechanism 20. All you need to do is place each product in the same way. The difference in the appropriate planar positional relationship between the film F and the product due to the difference in the product is automatically absorbed by changing the planar position of the film F.
[0107]
As described above, in the stretch wrapping apparatus 10, the film transport mechanism 40 and the film holding mechanism 50 are controlled according to the product, and the relative positional relationship between the product and the film F is appropriate for the product. Commodity packaging processing is performed appropriately, and the burden on the operator when placing the commodity on the introduction table 21 of the commodity introduction mechanism 20 is reduced as compared with conventional devices.
[0108]
(2)
In the stretch wrapping apparatus 10, the movement of the front clamp 54 and the like are controlled so that the heat seal position (planar position) is offset from the center of the product. In the conventional packaging apparatus, control is performed so that heat sealing is performed at the center on the bottom side of the product, but here, the film F can be heat sealed at a planar position away from the center of the bottom of the product. it can. If the film F is heat-sealed at such a position, the surplus film that hangs down from the heat-sealed portion will hang down from the portion near the end of the bottom of the product, and this surplus film is placed on the far end of the bottom of the product By stroking toward the side, it is possible to prevent the appearance of the product from deteriorating due to the concentration of the excess film only on one side from the center of the bottom of the product.
[0109]
Further, if the heat sealing position is offset from the center of the product (tray T) and the film F covering the product is similarly offset, the length of the surplus film F1 as shown in FIG. 20 (b-2). The excess film F1 can be made to hang down from the portion near the end of the bottom of the product while keeping the length unchanged from the conventional length, and the problem that the tip of the excess film F1 protrudes from the bottom of the product to the side is suppressed. Can do.
[0110]
(3)
When the size of the film F that covers the product is relatively large with respect to the product, the excess film that hangs down from the heat-sealed portion becomes relatively long, so the appearance of the product is offset by offsetting the heat seal position from the center of the product. It is desirable to improve.
[0111]
On the other hand, when the size of the film F covering the product is relatively small with respect to the product or when the heat seal position is offset from the center of the product, the product has characteristics that make it difficult to adjust the film tension in the packaging operation (for example, In the case of handling one round fruit and vegetables, it is desirable to perform conventional control.
[0112]
In view of this, in the stretch wrapping apparatus 10, in addition to the control for offsetting the heat seal position from the center of the product, the same control as the conventional control in which the heat seal position is approximately at the center of the bottom of the product is prepared and any control is selected. Whether to do it is decided according to the product. Here, the control unit 90 selects the former control when packaging a product including a tray with a flat bottom surface or a group of fruits and vegetables arranged horizontally, and the latter when packaging a single fruit or vegetable. Select the control.
[0113]
(4)
In the stretch wrapping apparatus 10, when the heat seal position is offset from the center of the product, the plane position of the central portion of the film F covering the product is offset from the center of the product, and the surplus film is stroked on the bottom of the product. Sometimes the tip of the surplus film is prevented from protruding sideways from the bottom of the product. And by adjusting the heat-sealing position and appropriately controlling the amount of offset of the film with respect to the product, the length of the excess film hanging down from the heat-sealed part is kept small, and the overlap of the film at the bottom of the product is partially To avoid concentrating on.
[0114]
(5)
In the stretch wrapping apparatus 10, the overlapping portion of the peripheral portion of the film F folded on the bottom side of the product is sandwiched between the rear folding plate 71 and the front fixing member 72 and heat sealed by applying pressure. Then, the rear folding plate moving motor 71a that plays a role of applying pressure to the overlapping portion of the film F is controlled by the control unit 90, and the pressure applied to the overlapping portion of the film F is adjusted based on the characteristics of the product. That is, the control unit 90 preliminarily estimates the film thickness of the overlapping portion of the film that is folded on the bottom side of the product based on characteristics such as the size and shape of the product, and the thickness of the folded and overlapped film and the product characteristics From this correlation, the pressure required for heat sealing is determined. As a result, the pressure in the heat seal is approaching an appropriate one suitable for the thickness of the overlapping film F, and products of various sizes must be packaged using the film F of a certain size as a packaging material. Even if this is not the case, the occurrence of defective seals is reduced.
[0115]
Here, there is a difference of about three times between the minimum set value and the maximum set value of the pressure applied to the overlapping portion of the film F, and several levels of pressure levels are set. For each product item, it is determined at which pressure level the heat sealing is performed.
[0116]
<Modification>
(A)
In the above embodiment, rubber is used as the elastic portions 71e and 71g. However, instead of rubber, a cushioning structure such as a plurality of hook-shaped protrusions made of nylon, polyester or the like on one surface of the hook-and-loop fastener is used. It is also possible to use a metal spring.
[0117]
(B)
In the above embodiment, the present invention is applied to the stretch wrapping apparatus 10 that moves the rear folding plate 71 to the front fixing member 72 and performs heat sealing on the relatively front side. In addition, the present invention can be applied to a stretch wrapping apparatus that has moved to the center and is heat-sealed in the center of the apparatus in a planar manner.
[0118]
【The invention's effect】
In the present invention, the driving means for applying pressure to the overlapping portion of the film is controlled by the control unit, and the pressure applied to the overlapping portion of the film is adjusted based on the characteristics of the package. Therefore, the film thickness of the overlapping portion of the film folded on the bottom side of the package object is preliminarily estimated based on characteristics such as the size and shape of the package object, and the thickness of the folded film and the characteristics of the package object are preliminarily estimated. If the pressure required for heat sealing is determined based on the correlation between the pressure and the pressure in the heat sealing can be brought close to the appropriate one according to the film thickness by controlling the drive means appropriately. Become.
[Brief description of the drawings]
FIG. 1 is a schematic side view of a stretch wrapping apparatus.
FIG. 2 is a schematic front view of the stretch wrapping apparatus (a view taken along the line II-II in FIG. 1).
FIG. 3 is a schematic plan view of a stretch wrapping apparatus.
FIG. 4 is a control block diagram of the stretch wrapping apparatus.
FIG. 5 is a view showing the movement of the first base and the second base of the lift mechanism.
FIG. 6 is a view showing the movement of the first base and the second base of the lift mechanism.
FIG. 7 is a plan view of a lift mechanism.
8 is a view taken along arrow VIII-VIII in FIG. 3;
FIG. 9A is a diagram showing parameters in the initial position adjustment of the left and right clamps.
(B) The figure which shows the junction part of a left clamp and a left pushing member.
FIG. 10 is a diagram showing a left-right folding operation.
FIG. 11 is a schematic plan view when the left and right folding is completed.
FIG. 12 is a view showing a rear folding operation.
FIG. 13 is a view showing a back folding operation and a heat sealing operation.
FIG. 14 is a schematic plan view of one plane during a rear folding operation.
FIG. 15 is a diagram illustrating a tray support state when a gap is formed between the tray bottom surface and the central support member.
FIG. 16 is a diagram illustrating an additional left and right folding operation when a gap is formed between the bottom surface of the tray and the central support member.
FIG. 17 is a diagram showing the movement of the front clamp in adjusting the heat seal position.
FIG. 18 is a view showing a state of a product after stroking excess film due to a difference in heat seal position.
FIG. 19 is a diagram showing the front-rear position adjustment of a film.
FIG. 20 is a diagram showing the state of an excess film based on the front and rear positions of the film and the heat seal position.
FIG. 21 is a diagram showing the overlapping state of heat-sealed films.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Stretch packaging apparatus 70 Heat sealing and film back-and-front folding mechanism 71 Back folding plate (1st member)
71a Rear folding plate moving motor (driving means)
72 Front side fixing member (second member)
90 control unit F film G product (packaged item)
T tray (packaged items)

Claims (4)

It is a packaging device that folds the peripheral part of the film covering the package to the bottom side of the package and heat-seals the overlapping part, and the thickness of the overlapping part of the film that performs heat sealing by changing the package is In changing packaging equipment,
First and second members for sandwiching overlapping portions of the film to be heat-sealed;
Drive means for applying pressure to the overlapped portion of the film via the first and second members;
A control unit that controls the driving means based on the relative size of the film and the packaged object to adjust the pressure applied to the overlapping portion of the film;
Packaging equipment with The control unit calculates the thickness of the film in the overlapping portion of the film from the relative size of the film and the packaged object, and controls the driving unit based on the thickness of the film.
The packaging device according to claim 1. When the size of the film covering the package is the same, the control unit increases the pressure applied to the overlapping portion of the film stepwise or continuously as the size of the package decreases. ,
The packaging device according to claim 1 or 2 . The driving means has a motor for pressing the first member against the second member;
The controller controls the voltage or current supplied to the motor to adjust the pressure applied to the overlapping portion of the film,
The packaging device according to any one of claims 1 to 3 .

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