JPH11105816A - Stretch film packaging machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce inertial force of a sub head to be lowered in conjunction with a main head from an uppermost position to reduce impact when the sub head comes against a stopper by stopping lowering of the main head once immediately before the sub head comes against the stopper. SOLUTION: A main head 9 and sub heads 10, 10' are coupled or separated to make an elevator head variable in size depending on a size of an object to be packaged. During stoppage when a rotation angle of a cam for raising/ lowering an elevator is around 360 deg., the sub heads 10, 10' are set at such a height that they may not come against stoppers 47, 47' in consideration of clearance between engaging members of the main head 9 and the sub heads 10, 10' and flexion of the sub heads 10, 10' due to inertial force for stopping lowering. Thus large inertial force due to lowering from the highest rising position caused on the sub heads 10, 10' is reduced, so that the sub heads 10, 10' can come gently against the stoppers 47, 47'.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wrapping machine for wrapping a product such as food (packaged material) with a stretch film in a backyard or the like of a supermarket. The present invention relates to an improvement of a packaging machine in which an area of an elevator head, which rises with an article placed thereon, is changed according to the size of the article to be packaged.

[0002]

2. Description of the Related Art An elevator head, on which an object to be packaged is placed, is lifted up from below with respect to a film stretched over a packaging part, and the upper surface of the object to be packaged is covered with a film. Various stretch film wrapping machines for folding and wrapping in a wrapper have been developed. In addition, since the sizes of the packages to be packaged in supermarkets and the like are mixed in size, the size of the elevator head on which the packages are placed is changed according to the size of the packages. It has been proposed as Japanese Patent Publication No. 5-58967.

[0003] Japanese Patent Publication No. 5-58967 proposes an elevator head which pushes up an object to be packaged toward a film, divided into a plurality of parts, and the divided elevator heads are connected or separated to form an object to be packaged. The area to be pushed up is changed according to the size of the package, thereby improving the packaging finish. Specifically, the width direction of the elevator head is divided into a main head (center head) and sub heads (left and right heads) located on both left and right sides thereof,
The main head alone or the main head and the sub head can be moved up and down in accordance with the size of the article to be packaged. The main head is moved up and down by a link mechanism that moves up and down by the rotation of the cam, and the sub head is restricted in position by a stopper so as to be accurately fitted at the lowermost position of the main head, and is stopped by the stopper by a connecting member. Connection or disconnection with the main head is performed.

[0004]

However, in the above-described conventional packaging machine, the main head has a lowering speed near the lowermost position due to the shape of the cam, but the main head is lowered in conjunction with the main head. Since the sub head is connected to the main head via the connecting member, the sub head may hit the stopper attached to the main body with strong impact due to play or bending of the connecting member connecting the main head and sub head. In addition, there is a problem that the noise and vibration are intense, and the mechanism is damaged or rattled, and the life is shortened. In addition, this approach cannot be adopted because the speed of packaging processing is greatly reduced if the vehicle descends very slowly after approaching the lowermost position because the speed is greatly reduced.

[0005] The present invention has been made in view of the above-mentioned problems of the prior art.
It is an object of the present invention to provide a packaging machine in which the sub head does not hit the stopper with a strong impact even when the sub head is connected to the main head and lowered without greatly reducing the processing speed.

[0006]

The technical measures taken by the present invention to solve the above-mentioned problems are as follows: an elevator head is connected to a driving member at all times and moves up and down; The main head is connected to the main head by a connecting member, and is constituted by a sub head which can be detached, and the area of the elevator head which moves up and down by moving the connecting member when the elevator head descends to the lowest position is the size of the packaged object. In the stretch film wrapping machine that performs packaging according to the elevator head, when the elevator head approaches the lowest position, the descending speed of the elevator head is greatly reduced or stopped, and then the elevator head is accelerated or restarted. At the lowest position.

[0007] A connecting method for connecting and detachably connecting the main head and the sub-head is such that an engaging member provided on a frame on which the sub-head is mounted is engaged with a frame provided with the main head. Not only the engagement method that is performed by detaching, a method using an electromagnetic clutch, a method in which one of the main head or the sub head grips the other, a method in which one of the main head or the sub head hooks the other with a hook, a main head or Any method, such as a method in which one of the sub heads fits a pin into the other, may be used. The drive of the elevator head is not limited to the one using a cam, and the method of controlling the rotation of the motor so that the height of the elevator head can be determined by the rotation position (rotation angle) of the output shaft of the motor without using the cam. And so on.

According to the above means, the descent speed of the main head for linking and lowering the sub head is greatly reduced or temporarily stopped just before the sub head hits the stopper on the main body side, and then the descent speed of the main head is accelerated. Alternatively, the secondary head reaches the lowermost position by restarting, so that the inertia force associated with the previous descent is almost eliminated by the deceleration or stoppage of the main head, and the sub head hits the stopper on the main body side. Therefore, the impact when the sub head hits the stopper is reduced, vibration and noise are also reduced, and damage to the mechanism and occurrence of backlash are eliminated.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 show an overall view of a stretch film packaging machine. A transport conveyor 1 for transporting a packaged object a to an elevator B provided inside the machine frame A is provided on the side of the machine frame A. A wrapping portion b is provided above, and a film for holding a film roll disposition portion 2 and a leading end of a film 3 ′ unwound from a film roll 3 set on the disposition portion 2 beside the wrapping portion b. The holding portion 4 is pulled out by a predetermined length with the front end of the film held by the film holding portion 4 interposed therebetween, and is stretched around the packaging portion b. A conveying means 5 for pre-stretching is arranged so that the film can be packaged by one narrow film roll. Above the conveying means 5, the end of the film 3 'covering the upper surface of the article to be packaged a is folded toward the bottom of the product. Discharging pusher 8 to discharge positioned above the rear folding plate 7 and the rear folding plate 7 and the left and right folding plates 6,6 'packaged the packaged product writing is located. Further, a position correcting device 48 is provided on the near side (upstream side) of the conveyor 1 of the packaging machine, which corrects the position in the direction orthogonal to the conveying direction of the product and also detects the width of the article to be packaged a. On the upstream side of the roller conveyor 49, a conveyor C having an accumulation conveyor 50 arranged in series is arranged, whereby the articles to be packaged are centered and supplied to the conveyor 1 of the packaging machine at a predetermined interval. It has become.

The conveyor 1 comprises a first conveyor 101 in which a plurality of belt-like belts are arranged in parallel at a predetermined interval, and a second conveyor
The conveyor 102 is configured to partially overlap, and the transport speed of the first conveyor 101 on which the packaged articles a sent from the transport device are placed is higher than the transport speed of the second conveyor, and the elevator Packaged a on B
On the belt surface of the second conveyor 102 for transporting
A stopper 103 for receiving the front end of the packaged article a carried in by the conveyor 101 is fixed. Thus, the transport of the packaged object a is performed based on the front end reference where the front end of the packaged object a is abutted against the stopper 103. The end of the second conveyor 102 for transporting the packaged article a onto the elevator B in the transport direction is inserted between a plurality of elevator heads constituting the elevator B, and the second conveyor 1
The transport surface of 02 is located above the elevator head surface before ascending. A dimension detecting sensor 51 for detecting the height and length (depth dimension) of the packaged article a conveyed by the driving of the conveyor 1 is disposed on the side of the conveyor 1 so as to face the conveying path. Have been.

The elevator head of the elevator B for mounting the packaged articles a is divided into a main head portion 9 located at the center and sub head portions 10 and 10 'located at the left and right of the main head portion 9, The main head portion 9 moves in the front-rear direction (in the direction of the depth dimension of the packaged object a) with respect to the substantially gate-shaped sliding frame 12 erected up and down on the guide columns 11, 11 'standing and fixed to the machine frame A. It is supported so as to be able to move up and down together with the sliding frame 12, and the left and right sub head portions 10, 10 ′ are attached to a frame 13 formed in an inverted gate shape, and
10 'is integrally formed, and the frame 13 has a guide post 14, which is fixed upright in parallel with the guide posts 11, 11'.
The main head 9 and the sub heads 10 and 10 'are supported on the 14' so as to be vertically movable.

The main head portion 9 is provided on the upper surface of a head base 9a having a substantially fork-like plane and a substantially L-shaped side surface with an interval enough to arrange a plurality of belt-like belts constituting the second conveyor 102. The main head portion 9 is detachably mounted on a mounting base plate 23 supported so as to be able to move back and forth horizontally with respect to the sliding frame 12. A moving means for horizontally moving the main head 9 in the front-rear direction is connected to the plate 23, and an elevating means for vertically moving the main head 9 up and down is connected to the sliding frame 12.

The moving means for horizontally moving the main head 9 in the front-rear direction includes two drive belts 24, 24 'at the bottom of the machine frame A as shown in FIGS. 24, 24 'are wound around large / small pulleys 26, 26' having different outer diameters fixed to the rotating shaft of the stepping motor 25, so that the moving distances of the drive belts 24, 24 'are different (the size is doubled). L-shaped frame 28 supported on a drive belt 24 ′ wound around a small pulley 26 ′ so as to be movable in the front-rear direction along a guide rod 27 attached to the side of the machine frame A. And the main head portion 9 is inserted into the vertical groove portion 28 'of the L-shaped frame 28.
The front end of a connecting rod 29 connected to the rear end of the mounting base plate 23 that supports is mounted. Therefore, the motor 25
Is driven to rotate the small pulley 26 ', and the drive belt 2
When the 4 'is rotated, the L-shaped frame 28 is moved in the running direction of the belt, and the main head 9 is moved through the connecting rod 29 fitted and engaged with the vertical groove 28' of the L-shaped frame 28. It is moved back and forth. A driving mechanism for driving the main head 9 up and down includes a groove 3 of a cam 30 rotated by a motor as shown in FIG.
At 0 ', a shaft provided on one side of an arm rod 31 which is formed in a substantially L-shape, is pivotally supported at the middle, and is vertically swingably mounted, is fitted and engaged. The other end of the connected connecting rod 32 is directly connected to the sliding frame 12 so that the main head 9 is moved up and down.

The sub heads 10, 10 'are constructed by mounting support rods 10b, 10b' on the upper surfaces of head bases 10a, 10a 'each having a substantially L-shaped side surface so as to be capable of falling down. The bases 10a and 10a 'are arranged in a straight line with their horizontal pieces overlapped in the vertical direction, and the front head base 10a is moved in the front-rear direction with respect to the rear head base 10a' (in the direction of the depth dimension of the packaged object a). It is supported so that it can be moved and adjusted. And the sub head unit 1
0, 10 'are connected to the inverted gate-shaped frame 13 as described above, and the frame 13 is connected to the drive belt 24 wound around the large pulley 26 of the moving means, and to the side of the machine frame A. The supporting plate 33 is movably supported in the front-rear direction along the attached guide rod 27, and is connected via a horizontal rod 34 fitted into a vertical groove 33 'of the supporting plate 33. In addition, the sub heads 10 and 10 'are connected to the head base 10a as described above.
And 10a 'are configured to move in the longitudinal direction so that the length of the head can be continuously varied, so that a flag 35 for position detection is attached to the drive belt 24 of the moving mechanism, and the drive belt 24 The detectors 36, 36 'are attached at predetermined intervals to the sides of the head so that the variable expansion / contraction state of the head can be detected. As a result, the main head 9 moves to an intermediate position with respect to the sub heads 10, 10 'when the sub heads 10, 10' expand and contract in the front-rear direction.

The main head 9 constructed as described above
The sub-heads 10 and 10 'are configured to be connected and separated according to the size of the article to be packaged a. The coupling / separation switching mechanism includes two sliding frames 12 to which the main head 9 is coupled.
The engaging rods 15 are horizontally installed and fixed at predetermined intervals, and an engaging member 16 that engages with and disengages from the engaging rods 15 is fixed to an upper end of a transmission unit 18 driven by a driving unit 17. . The engaging member 16 is a rod slightly narrower than the interval between the engaging rods 15 and is formed longer than the interval between the engaging rods 15. Transmission means 18 for fixing the engaging member 16 to the upper end
Is a projection member 19 having an engagement projection 19 'formed at one end (lower end) of the rod, and the engagement projection 1 at one end (upper end) of the rod.
9 ′ is formed with a concave member 20 formed by cutting out an engaging concave portion 20 ′ into which the engagement convex portion 19 ′ is fitted.
The engaging member 16 is connected at a right angle (T-shape) to the opposite side. A position control plate 21 having a square planar shape is mounted horizontally on the convex member 19 in the middle of the rod in the longitudinal direction, and the rod portion below the position control plate 21 is attached to the sub head portions 10 and 10. ′ Is attached to the bottom frame 13a of the frame 13
The position control plate 21 protruding downward through the bottom frame 13a and mounted on the upper surface of the bottom frame 13a
and is supported by the cover 13b fixed to the frame 13a so as to be rotatable in a fixed position in a vertical state with respect to the frame 13. Bottom frame 1
Position control plate 21 sandwiched between 3a and cover 13b
As shown in FIGS. 9 and 10, the periphery is parallel to the side of the engaging member 16 fixed to the rod, and the convex member 19 is halfway around the position control plate 21. Control pieces 22, 22 'to adjust so as not to stop at a great angle
Are biased by springs so as to rotate in opposite directions at relative positions.

The concave member 20 which engages and disengages with the above-mentioned convex member 19
Is composed of an upper member 20A and a lower member 20B which are spaced apart from each other so as to be able to move in the axial direction while engaged in the circumferential direction while engaging in the circumferential direction.
At the upper end, an engaging concave portion 20 'into which the engaging convex portion 19' of the convex member 19 fits and engages is cut out, and at the lower end, the engaging concave portion 20 'is out of phase with the forming direction of the engaging concave portion 20' by 90 °. Recess 37
Are formed. The lower member 20B has an upper member 20A at the upper end.
An engagement projection 38 that fits into and engages with the engagement recess 37 is provided with an auxiliary frame 39 ′ supported by a lower member 20 </ b> B inside a motor attachment frame 39 which is attached to the bottom frame of the machine frame A by hanging. The upper member 20A is provided with a flange protruding in the middle part in the axial direction, and the upper part is inserted through a through hole 40 formed in the bottom frame of the machine frame A so that the upper member 20A rises above the bottom frame. The upper portion of the upper member 20A is determined by the flange and the bottom frame. The engaging recess 37 is engaged with the engaging projection 38 of the lower member 20B. In the direction in which the spring 41 is resiliently mounted between them and
In other words, an urging mechanism is configured so that the upper member 20A can move downward and upward by a predetermined stroke. In addition, the vertical movement stroke of the upper member 20A is secured to a distance such that the projections and depressions are not damaged even when the projections and depressions do not engage with each other.

The lower member 20B of the concave member 20 is connected to an output shaft of a driving means 17 which is suspended from a motor mounting frame 39, and the concave member 20 is rotated by the operation of the driving means 17. . A flag 43 for detecting the rotation angle of the transmission means 18 is attached to the outer periphery of the lower member 20B at a right angle to the axis, and detectors 44 and 44 'are arranged at a right angle around the axis of the lower member 20B. ing. The attachment of the flag 43 is shifted by 90 ° from the engaging member 16 attached to the upper end of the convex member 19 of the transmitting means 18 and the engaging convex portion 19 ′ formed at the lower end of the convex member 19. By detecting the direction (position) of the flag 43 when the transmitting means 18 is rotated by the operation of the driving means 17 with the detectors 44 and 44 ', the engaging member 16 is detected.
Is engaged with or disengaged from the engagement rod 15 of the sliding frame 12 supporting the main head portion 9.

Further, a sliding frame 12 for supporting the main head 9
Flags 45 and 45 'for detecting the respective height positions are attached to the frame body 13 which connects and holds the sub head portions 10 and 10', and the flags 45 and 45 'are attached to the lower limit position (elevator lowering position). ) Are attached to the bottom frame of the machine casing A.
Thereby, the flag 45 attached to the sliding frame 12 and the flag 45 ′ attached to the frame 13 are detected by the detector 4 respectively.
6 and 46 ', it is determined that the main head 9 and the sub heads 10 and 10' are located at the lowered positions (see FIG. 15), and only the flag 45 'of the frame 13 is detected by the detector 4.
6 ', the main head 9 and the sub head 1 are detected.
It is determined that only the main head 9 is raised (see FIG. 17), and the flag 45 attached to the sliding frame 12 and the flag 4 attached to the frame 13 are separated.
If both detectors 5 'are not detected by the detectors 46 and 46', it is determined that the main head 9 and the sub heads 10 and 10 'are connected and located together at the ascending position. That is, by comparing the data of the detectors 46 and 46 ', it is determined whether the main head section 9 and the sub head sections 10 and 10' are connected or separated.

Stoppers 47, 47 for supporting the sub head members 10, 10 'at the lowest position are provided on the upper surface of the bottom frame of the machine frame A, which is located below the frame 13 supporting and supporting the sub head members 10, 10'. 'Is attached. On the upper surfaces of the stoppers 47, 47 ', cushioning materials 47a, 47a' for reducing the contact (impact) of the sub heads 10, 10 'are attached.

With the above construction, the size (area) in the width direction of the elevator head on which the article to be packaged a is placed can be varied in size in accordance with the size of the article to be packaged a. The connection / separation of the head 9 and the sub heads 10 and 10 'is switched by operating the driving means 17 and rotating the transmission means 18 in a state where the main head 9 is located at the lowest position. By rotating the engaging member 16 attached to the upper end of the convex member 18 and arranging it so as to intersect at right angles with the engaging rod 15 of the sliding frame 12 supporting the main head portion 9, The transmission means 18 is lifted together with the sliding frame 12 supporting the portion 9, but since the transmission means 18 is configured to be vertically separated on the way, only the upper convex member 19 is together with the sliding frame 12. Will rise. Then, the convex member 19 of the transmission means 18
Is fixed via the position control plate 21 to the frame 13 that connects and holds the sub heads 10 and 10 ′, so that the frame 13 that connects and holds the sub heads 10 and 10 ′ is also connected to the main head 9. Will be raised together. (See FIG. 16) The fact that the main head section 9 and the sub head sections 10, 10 'are integrally raised means that the detectors 46, 46' for detecting the height position of each elevator head are "ON". (The flags 45 and 45 'are separated from the detectors 46 and 46').

When the width of the article to be packaged a is small and the width of the elevator head is small, the driving means 17 is operated to rotate the transmitting means 18, whereby the engaging means attached to the upper end of the transmitting means 18 is engaged. The member 16 is rotated so that the direction of the engaging member 16 is parallel to the engaging rod 15 of the sliding frame 12 so that the engaging member 16 does not engage with the engaging rod 15. As a result, the sliding frame 12 supporting the main head portion 9 is
6 and only the sliding frame 12 is raised, and the sub head 1
The frame 13 holding the 0 and 10 'connected and held at the lowest position. (See FIG. 17) The fact that only the main head section 9 is raised, that is, the main head section 9 and the sub head sections 10 and 10 ′ are separated, indicates that the above-described detector 46 is “ON”. Is determined from the fact that the detector 46 'is "OFF".

As described above, the main head 9 and the sub head 1
The size of the elevator head is changed according to the size of the packaged object a by connecting / separating 0, 10 '. When lowering the variably adjusted elevator, for example, as shown in FIG. When the sub heads 10 and 10 'are separated and only the main head 9 descends, the direction of the engaging member 16 is the direction that collides with the engaging rod 15 of the sliding frame 12, or as shown in FIG. The main head 9 and the sub heads 10, 1
0 'is connected to the convex member 19 of the transmission means 18 in the use state.
When the concave and convex portions 20 are not aligned with each other, even if the elevator B is lowered and the opposing members collide with each other, the concave member 20 of the transmission means 18 is provided with a mechanism for stroke in the axial direction. In this portion, the impact is absorbed and the switching device can be prevented from being damaged. When the elevator is lowered, even if the projections and depressions of the projection member 19 and the recessed member 20 of the transmission unit 18 do not mesh, the driving unit 17 is always rotated by 180 °, which is the amount of engagement, so that the engagement is reliably performed. be able to. Detectors 46 and 4 for detecting the height position of each of the divided elevator heads.
The driving means 17 is actuated based on the detection signal of 6 'to correct the direction of the engaging member 16 or the deviation of the concave and convex portions of the convex member 19 and the concave member 20 of the transmitting means 18 so as to engage properly. can do. In particular, at the time of start after reset, it is not known what the state is.
6, 46 'and the signals of the detectors 44, 44', it is determined whether the orientation of the engaging member 16 is not appropriate or the presence or absence of unevenness is determined. It is good to operate.

FIG. 20 is a displacement diagram showing the relationship between the rotation angle (0 ° to 360 °) of the cam for raising and lowering the elevator and the height position of the elevator, which will be described in detail below. (A) Approximately 45 ° to 135 ° is a head switching period in which the area of the head is changed in width at the lowest position of the elevator. That is, the transmission means 18 to which the engagement member 16 is attached
The convex member 19 and the concave member 20 connected to the output shaft of the driving means 17 are engaged with each other, so that the driving member 17 can be operated to rotate the engaging member 16, and the main head 9 and the sub heads 10, 10 'Can be switched between connection and disconnection. (B) The elevation is made slightly before 180 °, and the height position is stopped and maintained. At this point, the packaged object a has already been located at the predetermined position of the elevator head. The lowermost position is a position lower than the conventional packaging machine, and the carry-in height of the packaged object a is the same as that of the conventional packaging machine. This is to reduce the That is, the height at 180 ° is equal to the height of the conventional elevator head. (C) At about 270 °, the elevator is at the highest position, and at this position, the end of the film covering the upper surface of the packaged object a is folded. (D) The suspension period around 360 ° (also 0 °)
In this height position, even if play of the engaging member between the main head 9 and the sub heads 10 and 10 'and bending of the sub heads 10 and 10' due to inertia force for stopping the descent are added, the sub head is not moved. It does not hit the stoppers 47, 47 ', and has a height just before hitting the stoppers 47, 47'. Here, since it is sufficient that the inertial force of the sub heads 10 and 10 'can be absorbed, the descent may be performed very slowly with a large deceleration without completely stopping the descent. (E) The re-acceleration period following the above-mentioned suspension period (about 15 to 2)
0 °), the sub heads 10 and 10 ′ are
7 '. Alternatively, it is a period in which the main head 9 starts to descend again in order to bring the sub head into contact with the stopper quickly. Since the large inertial force that has descended from the highest position of the sub heads 10, 10 'has disappeared at this time, the sub heads 10, 10' are stopped by the stoppers 47, 47 '.
Contact quietly against. Therefore, there is no need to lower the rotation speed of the cam as compared with the conventional case.

In the above-described apparatus, the speed of the sub head at the time of hitting the stopper can be reduced as compared with the related art even if the height position at which the sub head hits the stopper and the height of the size switching point (lowest descent position) are relatively large. For this reason, a play of the continuous member, that is, a large gap between the engaging rod 15 and the engaging member at the time of switching can be ensured without any trouble, so that the switching operation can be reliably performed. Further, when the sub head hits the stopper, the inertia force of the main head is not applied to the stopper, that is, the main head is further advanced at that time, so that the impact at this time is further reduced. In addition, the main head is temporarily stopped while the contact portion of the sub head to the stopper is deflected to bend, and the main head is restarted at the timing of leaving after approaching the stopper so that the sub head hits the stopper. The use of flexural vibration can further reduce the impact. The connecting member for connecting and disconnecting the main head and the sub head described above is not limited to the above-described embodiment, and may be configured to directly connect the main head and the sub head, or via another connecting member between the two heads. Or indirectly connected by any means. The connection or disconnection of the sub head to or from the drive mechanism for driving the main head is also included in the indirect connection form, and the present invention can be applied.

[0025]

According to the stretch film wrapping machine of the present invention, the area of the elevator head for mounting and supporting the packaged object is changed according to the size of the object to be packaged. When the main head and the sub head are connected to increase the head area, the descent of the main head is stopped almost immediately before the sub head hits the stopper, so that the main head is linked with the main head from the highest position. After the inertial force of the sub head descended after being almost eliminated, the sub head descends and hits the stopper. Therefore, the impact when the sub head hits the stopper is reduced, the vibration and noise are reduced, the mechanical part is not damaged and the backlash is not generated, and the life is shortened without causing a significant decrease in the packaging processing speed. It is possible to provide a packaging machine that can be extended and can withstand long-term use. Further, even if the connection accuracy of the connecting member for connecting the main head and the sub head (the accuracy relating to misalignment between the two heads) can be reduced by the above configuration, a strong impact with the stopper can be avoided. The assembling accuracy can be relatively rough and can therefore be manufactured inexpensively. Further, even if the deflection of the sub head is increased, a strong impact with the stopper can be avoided, so that it is not necessary to increase the rigidity of the sub head, and as a result, there is an advantage that it can be manufactured at low cost.

According to the second aspect of the present invention, a strong impact with the stopper can be avoided, so that the engagement of the connecting member can be increased and the engagement can be facilitated. And since it is a connection member by an engagement, it is inexpensive structure, has high durability, and can obtain a strong connection force. Further, claim 3
According to the configuration described in (1), the elevator can be reliably moved up and down with an inexpensive configuration.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view schematically showing a stretch film packaging machine according to the present invention.

FIG. 2 is a vertical sectional front view of FIG.

FIG. 3 is a partially cutaway plan view showing a range from the transfer device of FIG. 1 to an elevator.

FIG. 4 is an enlarged front view of an elevator part.

FIG. 5 is a cutaway plan view of the same part.

FIG. 6 is a sectional view taken along the line (6)-(6) of FIG.

FIG. 7 is a sectional view taken along the line (7)-(7) of FIG.

FIG. 8 is a partially cutaway front view showing an engagement relationship between a central head portion and a transmission means.

FIG. 9 is a perspective view showing a convex member and a concave member to which an engaging member is attached.

FIG. 10 is a cross-sectional view taken along the line (10)-(10) in FIG. 8, where (a) shows a state controlled to an appropriate state, and (b)
FIG. 4 is a diagram showing a state in which a halfway state is returned to an appropriate state.

FIG. 11 is a sectional view taken along the line (11)-(11) of FIG.

FIG. 12 is a cross-sectional view showing an urging mechanism provided in a concave member of the transmission means.

FIG. 13 is an explanatory diagram showing a positional relationship between an engaging concave portion of the concave member and a flag for detecting the direction of the engaging member.

FIG. 14 is a diagram showing a relationship between the flag and a detector.

15A is a front view showing a state in which the center head and the left and right heads are located at the lowest position, and the engaging member and the center head are engaged with each other. FIG. FIG.

FIG. 16A is a front view showing a state in which the central head portion and the left and right head portions are connected and ascending, and FIG. 16B is an explanatory diagram showing directions of an engaging member and a flag.

FIG. 17A is a front view showing a state in which a center head portion and left and right head portions are separated, and only the center head portion rises;
(B) is an explanatory view showing directions of the engagement member and the flag.

FIG. 18 is a schematic diagram showing a form in which the center head section and the left and right head sections are separated, and when the center head section descends, the orientation of the engagement member does not match and the head member collides.

FIG. 19 is a schematic view showing a form in which the central head portion and the left and right head portions are connected, and when the connected elevator head descends, the convex and concave portions of the transmitting member are deviated in the concave and convex directions.

FIG. 20 is an elevator height displacement diagram showing a relationship between a rotation angle of a cam for raising and lowering the elevator and an elevator height.

[Explanation of symbols]

A ... Machine frame B ... Elevator 1 ... Conveyor 9 ... Main head part 10, 10 '... Sub head part 17 ... Driving means 18 ... Transmission means 19 ... Convex member 20 ... Concave member 47, 47' ... Stopper 30 ... Cam

Claims (3)

[Claims] 1. An object to be packaged is placed on an elevator head and pushed up from below the stretch film stretched over the packaging part to cover the upper surface of the object to be packaged, and the end of the film is covered by the film. In a packaging machine that folds and packs on the bottom surface, the elevator head is always connected to a driving member and moves up and down, and the left and right sides of the main head are connected to and separated from the main head by connecting members, and are freely detachable. In the stretch film packaging machine that is configured with a sub head and changes the area of the elevator head that moves up and down by moving the connecting member when the elevator head descends to the lowest position according to the size of the article to be packaged, and performs packaging. When the elevator head approaches the lowest descent position, the descent speed of the elevator head is greatly reduced or stopped, and then accelerated or restarted Stretch film wrapping machine, characterized in that to reach the elevator head to the most-lowered position and. 2. A connecting member for connecting and disconnecting the main head and the sub-head by engaging and disengaging an engaging member provided on a frame to which the sub-head is attached with respect to the frame having the main head. The stretch film packaging machine according to claim 1, wherein: 3. The stretch film packaging machine according to claim 1, wherein the elevator head is moved up and down by rotating a cam having a predetermined shape.