JPH04242507A - Band tensioner in packer - Google Patents

Abstract

PURPOSE:To smoothly hold and release a band and finely adjust it, by actuating a cramp jaw to the opposite direction against tightened direction of a tension jaw through a spring and holding the band by the tension jaw and further, by freely moving synchronously with the cramp, jaw. CONSTITUTION:When the front end of a band moves around in the band guide arch once and returns back, the band moves out from the band guide arch, a tension cam 23 is rotated, and a tension arm 13 moves to the right. As the tension jaw 14 moves to the tension direction, it presses via the band on the holder 16 of a cramp jaw 15 on the moving trace. In this time, the cramp jaw 15 of the cramp jaw arm 18 is actuated to the opposite direction of the tension through the spring 29 and it holds only when the tension jaw 14 contacts the cramp jaw 15. Tension jaw moves subsequently to let the cramp jaw 15 move synchronously.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a band tightening device for a packaging machine, and more particularly to a tension jaw provided at the end of a tension arm which is moved by a tension cam with a constant stroke, and which is engaged with the tension jaw via a band. The present invention relates to a band tightening device that grips and tightens a band using removable clamp jaws.

0002

2. Description of the Related Art In a conventional band tightening device for a packaging machine, as shown in FIGS. 5 and 6, a band guide groove is provided in the upper part of a tension arm 63 which is slid by a constant stroke by a tension cam 62 and automatically returned by a spring 64. 83, a jaw 75 which is urged in one direction by a spring 73 in the guide groove 83 is rotatably supported, and the upper end of a freely slidable adjustment arm 67 is brought into contact with the jaw 75. an adjuster 68 is rotatably disposed in parallel with a shaft in the vicinity of the lower end of the adjustment arm 67; the adjuster 68 is provided so as to be engageable with the lower end of the adjustment arm 67; and the jaw 75 is biased. The adjustment arm 67 and the adjuster 68 are interlocked via the spring 72 having a resistance larger than the resistance of the spring 73, and the upper end of the adjustment arm 67 is arranged in a direction opposite to the tightening direction of the tension arm 63 when the band is tightened. The two are connected to each other so as to be biased in the direction, and a tightening adjustment cam 77 is eccentrically supported and provided so as to be freely engageable with the adjuster 68.

According to this device, the tightening adjustment cam 77
By rotating, the position where the jaw 75 grips the band in the band guide groove 83 can be adjusted.
You can adjust the tightening strength.

That is, when the band is tightened, the tension arm 63 and the adjustment arm 67 are moved so that the adjustment arm 67 is provided with a protruding rod 71 by a spring 72.
The adjuster 68 rotates in conjunction with the adjuster 68, and the pin 78 of the adjuster 68 comes into contact with the tightening adjustment cam 77 that is waiting at a predetermined position.At this point, the adjuster 68 is fixed and the rotation of this part is stopped. Furthermore, as the tension arm 63 slides, the adjustment arm 67 attempts to return via the spring 72 by the protruding rod 71 of the adjuster 68, so that the tip of the adjustment arm 67 moves toward the left in the figure relative to the tension arm 63. Since the spring 72 is larger than the resistance of the spring 73 which urges the jaw 75, the tip of the adjustment arm 67 pushes the pin 74, the jaw 75 grips the band in the band guide groove 83, and the tension arm 63 continues to slide. Tightening is performed by

[0005]

[Problems to be Solved by the Invention] In the conventional band tightening device for a packaging machine, the tightening strength of the band is adjusted by moving the jaw 75 into the band guide groove while the tension arm 63 is slid by a certain stroke by the tension cam 62. This is done by adjusting the timing of gripping the band in 83. When the jaw 75 grasps and releases the band in the band guide groove 83, the distal end of the adjusting arm 67 is forced by the force of the spring 72 toward the pin 74 of the jaw 75, and the jaw 75 is guided by the band. The difference in resistance from the spring 73, which urges it in one direction away from the groove 83, has a subtle effect.

That is, when the pin 78 of the adjuster 68 comes into contact with the tightening adjustment cam 77, the adjustment arm 67 is pulled by the spring 72, and the adjustment arm 67
The tip of the spring 73 presses the pin 74 against the urging force of the spring 73 and rotates the jaw 75 to grip the band in the band guide groove 83. However, when the urging force of the spring 73 is relatively strong, As the tension arm 63 slides, the force for rotating the jaw 75 relative to the jaw 75 becomes weaker, and since the jaw 75 does not rotate immediately, a problem arises in that fine adjustment of the tightening force becomes difficult.

On the other hand, if the biasing force of the spring 73 is weak,
The jaw 75 immediately rotates and grips the band in the band guide groove 83, but after the sliding movement of the tension arm 63 reaches the peak of a certain stroke, the jaw 75 releases the gripping band due to the biasing force of the spring 73. Since the biasing force of the spring 73 is weak, there is a problem in that if the band gripping portion of the jaw 75 is biting into the band, it may not be able to be released. In other words, the band gripping part of the jaw 75 has serrated protrusions in order to prevent the band from slipping between the gripping parts of the band guide groove 83, so the band gripping part of the jaw 75 has serrated protrusions carved therein to prevent the band from slipping between the gripping parts of the band guide groove 83. In some cases, the jaw 75
There was a problem in that the band gripping portion of the band bits into the band and the urging force of the spring 73 which urged the jaws 75 away from the band guide groove 83 was weak, making it impossible to release the grip of the band by the jaws.

Further, for the above reasons, depending on the shape of the band gripping portion of the jaws 75, the type of the band, and the type of package, the band gripped in the band guide groove 83 by the jaws 75 may slip when tightened. A problem sometimes arose in that it was not possible to tighten the area.

The present invention was developed to solve the above-mentioned problems, and when the band is tightened, the band held by the tension jaws does not slip or get caught in the jaws.
It is an object of the present invention to provide a band tightening device for a packaging machine that smoothly grips and releases a band and allows fine adjustment of the band tightening force.

0010

[Means for Solving the Problems] In order to achieve the above object, in a band tightening device for a packing machine of the present invention, a tension cam rotates in response to a signal in which the band surrounds an object to be packed placed on the main body of the packing machine. 23, a tension arm 13 is provided which slides at a constant stroke, and a clamp jaw arm 18 that is engaged with a tightening adjustment cam 25 and waits on the sliding locus of the tension jaw 14 provided at the end of the tension arm 13 in the direction of tightening action. Clamp jaw 1
5 is slidably provided, and the clamp jaw 15 is biased via a spring in a direction opposite to the tightening direction of the tension jaw 14, and the tension jaw 14
The band is gripped between the standby clamp jaw 15 and is slidably provided in synchronization with the clamp jaw 15.

Further, when the tension jaw 14 returns in the opposite direction to the tightening action direction, the clamp jaw arm 18 is engaged with the tightening adjustment cam 25 and is kept on standby in the sliding trajectory, so that the tension jaw 14 and the clamp jaw 15 It may also be provided to release the grip of the band.

Furthermore, a tension crank 21 is rotatably provided to be rotated by the tension cam 23, and the tension arm 13 is interlocked with the tension crank 21 via a rod so as to slide at a constant stroke. A clamp jaw crank 22 is provided rotatably to engage with the tightening adjustment cam 25 and wait, and the clamp jaw arm 18 is rotatably connected to one end of the clamp jaw crank 22 via a rod. The clamp jaw 15 of the arm 18 can also be made to stand by on the sliding trajectory of the tension jaw 14 in the tightening action direction.

[0013]

[Operation] The tightening adjustment cam 25 is rotated to engage the clamp jaw crank 22 with the tightening adjustment cam 25, and the clamp jaw 15 provided on the clamp jaw arm 18 is moved along a predetermined sliding trajectory in the tightening action direction of the tension jaw 14. on standby.

When an object to be packed is placed on the packing machine main body and the band passes between the tension jaws 14 and clamp jaws 15 and is wound around the object, the band is surrounded by the band. The tension cam 23 rotates, and the tension arm 13 starts sliding with a constant stroke. Then tension arm 13
The convex portion 4 formed on the grip portion 16 of the tension jaw 14 of
1 is a clamp jaw 15 waiting on this sliding trajectory.
The tension jaw 14, which continues to slide, presses the clamp jaw 15 and slides in synchronism to tighten the band. At this time, the clamp jaw arm 18 separates from the tightening adjustment cam 25. When the tension arm 13 reaches the apex of its constant stroke, a welding and cutting mechanism within the packing machine main body welds and cuts the overlapping portions of the leading end and supply end of the packing band, thereby packing the object.

Further, when the tension cam 23 rotates and the tension arm 13 returns, the tension jaw 1
4 and the clamp jaw 15 return to the state holding the cut end of the band, and in the process of returning, the clamp jaw arm 1
8 engages and stops with the tightening adjustment cam 25, so the clamp jaw 15 stops, and the tension jaw 14, which subsequently returns, separates from the clamp jaw 15 and releases the gripped band. Then, the clamp jaw 1
5 will be on standby for the next tightening of the packing band.

When the tension arm 13 returns to its original position,
The band is fed outside the packaging machine body or into the band guide arch by a band supply mechanism within the packaging machine body.

[0017]

[Example] The first embodiment will be explained with reference to the drawings. In Fig. 1, 51 is the machine frame of the main body, which is wrapped around the object to be packed with a band, and after the band is pulled back, it is rotated by a signal surrounding the object to be packed. A tension cam 23 is supported on the machine frame 51. 13 is a tension arm whose lower end is attached to the shaft 3 of the machine frame 51.
7 and is connected to the machine frame 51 via a spring 64. A lever 17 having a trochanter provided substantially orthogonally to and integrally with the tension arm 13 is connected to the tension cam 23.
The tension arm 13 is configured to be in contact with the cam surface of the tension cam 23, and to be slid by a certain stroke by the rotation of the tension cam 23, and to be automatically returned by the spring 64.

A tension jaw 14 is protruded from the upper part of the tension arm 13, and a band passage passage 19 is formed in the upper part of the tension jaw 14. A tension arm shooter 12 is located below the tension jaw 14.
is rotatably attached by a hinge, and the upper end of the band passing path of the tension arm shooter 12 faces the band passing path 19.

Reference numeral 18 denotes a clamp jaw arm, the lower end of which is supported on a shaft 37 that supports the tension arm 13, and the upper part of the clamp jaw arm 18 has a sliding trajectory of the tension jaw 14 of the tension arm 13 in the tightening action direction. A clamp jaw 15 is provided between the tension jaw 14 and the clamp jaw 15 so that the band can be gripped. The clamp jaw arm 18 is connected to the machine frame 51 via a spring 29, and urges the clamp jaw 15 in a direction opposite to the tightening direction of the tension jaw 14.

Note that the tension jaw 1 of the part where the band is gripped by the tension jaw 14 and the clamp jaw 15
The gripping portion 16 of No. 4 is formed to have a flat surface or a slightly uneven surface to the extent that no problem occurs when feeding the band, and the gripping portion 16 of the clamp jaw 15
The gripping portion 16 is provided with protrusions to prevent the gripped band from slipping.

Furthermore, as shown in FIG.
It is also possible to form a concave portion 41 in the gripping portion 16 of the tension jaw 14 to such an extent that it does not interfere with band feeding, and further to form a convex portion 42 in which the gripping portion 16 of the clamp jaw 15 fits into the recessed portion.

The clamp jaw arm 18 has a crank portion 28 extending downward from the position where it is supported by the shaft 37. On the other hand, the tightening adjustment cam 25 is eccentrically supported on the machine frame 51 and is rotatably provided. , the tightening adjustment cam 25 is brought into contact with and engaged with the crank portion 28 of the clamp jaw arm 18, and the clamp jaw 1 of the clamp jaw arm 18 is tightened.
5 is the tension jaw 1 of the tension arm 13;
When the tension jaw 14, which slides in the tightening action direction, synchronously slides the clamp jaw 15 via the band, the crank part 28 performs the tightening adjustment. It is configured to move away from the cam 25. In addition, the tightening adjustment cam 2
A contact plate 27 made of an abrasive material such as resin is provided on the contact surface of the crank part 28 with the crank part 5 .

The front end of the band passing path 19 above the tension jaw 14 in the band feeding direction faces the end surface of the band passing path of a band shooter 52 for guiding the band to a known band welding and cutting mechanism. A pair of feed rollers 53 and 54 are provided in the band passing path of the shooter 52 to pinch the band, feed it, and pull it back.

In the above embodiment, the tightening device 10 is placed on the band supply end side, and the tightening device 10 grips and tightens the band supply end side. It is also possible to arrange it so that the supply end side is gripped and fixed, and the band tip end side is tightened.

Next, the operation of the first embodiment will be explained.
When the tightening adjustment cam 25 is rotated and set at a predetermined position corresponding to the desired amount of band tightening, the tightening adjustment cam 25 contacts the crank part 28 via the backing plate 27, and the clamp jaw arm 18 is rotated to set it at a predetermined position corresponding to the desired amount of band tightening. stop in position. That is, the clamp jaw arm 18 engages with the tightening adjustment cam 25 to tighten the clamp jaw 1 of the clamp jaw arm 18.
5 is waiting on the sliding track in the tightening action direction of the tension jaw 14.

Therefore, the object to be packed is placed on the main body of the packing machine, and the band coil of the band reel (not shown) or the band in the band pool box is pulled out, and the tip of the band is passed from the lower end of the tension arm shooter 12 to the band of that part. It is inserted into the band passage of the band shooter 52 through the passage. Then, after the forward rotation of the feed rollers 53 and 54 causes the band tip to go around the band guide arch and reach the band welding mechanism, the feed rollers 53 and 54 are rotated in the reverse direction by turning on the start switch, and the band is pulled back. Then, the band escapes from the band guide arch, and when the tension cam 23 rotates toward the front in FIG.

As the tension jaw 14 of the tension arm 13 slides in the tightening direction, it presses via the band against the gripping portion 16 of the clamp jaw 15 which is waiting on the sliding trajectory of the tension jaw 14 as described above. . At this time, the clamp jaw 15 of the clamp jaw arm 18
is biased via the spring 29 in a direction opposite to the tightening direction of the tension jaws 14, so that the band is gripped only when the tension jaws 14 contact and press the clamp jaws 15. tension jaw 14
When the clamp jaws 14 continue to slide, the tension jaws 14 resist the biasing force of the spring 29 and cause the clamp jaws 15 to slide synchronously. That is, the tension jaw 14 and the clamp jaw 15 slide to the top of the constant stroke of the tension jaw 14 to tighten the band while gripping the band with the grip portion 16 between the tension jaw 14 and the clamp jaw 15. During this time, the crank portion 28 of the clamp jaw arm 18 separates from the contact surface of the tightening adjustment cam 25.

Furthermore, since the gripping surfaces of the tension jaw 14 and the clamp jaw 15 are in a direction substantially perpendicular to the sliding locus, the band becomes substantially dogleg-shaped during tightening, making it difficult to slip between the jaws. Therefore, the protrusion of the grip part 16 of the clamp jaw 15 does not need to be provided at such an acute angle that it bites into the band surface.

Furthermore, the gripping portions 16 of the recessed portion 41 and the convex portion 42 provided on the tension jaw 14 and the clamp jaw 15, which fit into each other, further ensure the gripping of the band between the jaws, and when the band is tightened, the band moves between the jaws. There is almost no slipping.

Furthermore, by engaging the tension adjustment cam 25, the waiting position of the clamp jaw 15 of the clamp jaw arm 18 can be finely adjusted.
Since the band is gripped as soon as it slides in the tightening action direction and comes into contact with the clamp jaws 15, there is little variation at the start of tightening, and a stable tightening amount is set.

When the tension arm 13 reaches the apex of its constant stroke, a known welding and cutting mechanism welds and cuts the overlapping portions of the leading end and supply end of the packing band, and the object to be packed is packed.

When the tension cam 23 further rotates and the tension arm 13 begins to rotate to the left in the plane of FIG. The band returns in synchronization with the tension jaws 14 while pressing and gripping the tip of the band against the tension jaws 14. Furthermore, when the tension arm 13 rotates to the left on the plane of the figure, the crank portion 28 of the clamp jaw arm 18
The clamp jaw 15 of the clamp jaw arm 18 comes into contact with and engages the tightening adjustment cam 25 through the clamp jaw arm 18, and the clamp jaw 15 of the clamp jaw arm 18 waits on the sliding trajectory in the tightening action direction of the tension jaw 14 for the next tightening of the packing band. However, since the tension arm 13 continues to rotate, the tension jaw 1
4 separates from the clamp jaw 15 and releases the grip on the tip of the band. At this time, the tension jaws 14 and clamp jaws 15 are separated from each other in a direction perpendicular to the surface of the band, so there is no possibility that the jaws will bite into the surface of the band and be unable to release the band. When the tension arm 13 returns to its original position, the leading end of the band is fed to the outside of the packaging machine body or into the band guide arch by normal rotation of the feed rollers 53 and 54.

Next, a second embodiment will be described with reference to FIG. 3, omitting the same parts as the first embodiment. A tension arm 1 having a tension jaw 14 projecting from the upper part thereof
The lower ends of the clamp jaw arm 18 provided with the clamp jaw 15 and the clamp jaw 15 are respectively slidably supported on the shaft 37 of the machine frame 51 as in the first embodiment, and A crank arm shaft 35 is provided approximately parallel to the shaft 37, and an L is provided on the crank arm shaft 35.
A character-shaped tension crank 21 and a T-shaped clamp jaw crank 22 are pivotally attached to each other so as to be freely slidable, and the upper ends of the tension crank 21 and the clamp jaw crank 22 are connected to the tension arm 1, respectively.
3 and the clamp jaw arm 18 via rods 31 and 32 having rod ends at both ends, the length of which can be adjusted freely.

A trochanter is pivotally attached to the other end of the tension crank 21 and one central protruding end of the clamp jaw crank 22, and the tension cam 23 and the tension cam 23 are wedged to the tension cam 36 via the trochanter. , is provided so as to be driven by the band release cam 24. Note that the tension crank 21 connects the shaft to the tension cam 23.
It is always biased via the spring 30 so that it follows.

On the other hand, the lower end of the lower protruding piece of the clamp jaw crank 22 is biased via a spring 29 so that the clamp jaw crank 22 is rotated counterclockwise in the plane of FIG. That is, the clamp jaw crank 22 is interlocked with the rod 32 connected to the upper end thereof, and urges the clamp jaw 15 of the clamp jaw arm 18 in a direction opposite to the direction in which the tension jaw 14 tightens.

Then, the tightening adjustment cam 25 is wedged eccentrically to a shaft 26 that is separately supported substantially parallel to the crank arm shaft 35, and the tightening adjustment cam 25 is fixed to the lower end of the lower protruding piece of the clamp jaw crank 22. The clamp jaw crank 22 is made to stand by at a predetermined position by abutting and engaging with the applied backing plate 27. That is, by arbitrarily rotating the tightening adjustment cam 25 and waiting the clamp jaw crank 22 at a predetermined position, the clamp jaw 15 of the clamp jaw arm 18 is adjusted to the tension via the rod 32 connected to the upper end of the clamp jaw crank 22. When the tension jaw 14 of the arm 13 is made to stand by at any position on the sliding locus in the tightening direction, and then the tension jaw 14 sliding in the tightening action direction synchronously slides the clamp jaw 15 via the band, the clamp jaw 15 The abutment plate 27 at the lower end of the lower protruding piece of the clamp jaw crank 22 that is interlocked with the clamp jaw crank 22 is configured to separate from the contact surface of the tightening adjustment cam 25.

Further, the band release cam 24 releases the clamp immediately after the tension jaw 14 reaches the peak of its sliding movement in the tightening direction of the portion, the welding and cutting of the band overlapping portion are completed, and the tension jaw 14 returns to its original position. Joe 15
This is to stop the tension jaw 14 and the clamp jaw 15 to release the band gripped between the tension jaw 14 and the clamp jaw 15. That is, immediately after the tension jaw 14 returns, the band release cam 24 rotates the clamp jaw crank 22 in the counterclockwise direction on the plane of FIG. temporarily stopping, that is, temporarily stopping the clamp jaw 15 of the clamp jaw arm 18 via the rod 32;
After separating the clamp jaw 15 from the tension jaw 14 and releasing the gripped band, the tension jaw 14
The clamp jaws 15 are formed so as to return while maintaining the distance from each other.

Next, the operation of the second embodiment will be explained without explaining the same parts as the first embodiment. When the tightening adjustment cam 25 is rotated and set at a predetermined position corresponding to the desired amount of band tightening, The tightening adjustment cam 25 rotates the clamp jaw crank 22 which is in contact with the lower end of the protruding piece of the clamp jaw crank 22 via the backing plate 27, and stops it at a predetermined position. As a result, the clamp jaw 15 of the clamp jaw arm 18 is interlocked via the rod 32 connected to the upper end of the clamp jaw crank 22, and waits at a predetermined position on the sliding trajectory of the tension jaw 14 in the tightening action direction. After the band is wound around the object to be packed placed on the packing machine main body, the tension cam 23 wedged on the tension cam shaft 36 rotates, and tension is applied via a trochanter pivoted on one end of the tension crank 21. The crank 21 is slid clockwise on the plane of FIG. 3. Accordingly, the tension jaw 14 of the tension arm 13 slides in the same direction, that is, in the tightening action direction, via the rod 31 connected to the upper end of the tension crank 21. Then, as in the first embodiment, the tension jaw 14 grips and tightens the band on the grip portion 16 of the clamp jaw 15 that is waiting on the sliding trajectory.

After the tension jaw 14 reaches the peak of its sliding motion and the welding and cutting of the band overlapping portion is completed, the tension arm 1 is moved by the continued rotation of the tension cam 23.
The tension jaw 14 of No. 3 returns in the counterclockwise direction on the plane of FIG. 3 via the rod 31 of the tension crank 21. However, the band release cam 24 temporarily stops the rotation of the clamp jaw crank 22 in the counterclockwise direction in the plane of FIG. The clamp jaw 15 is interlocked by a rod 32 connected to the upper end of the clamp jaw crank 22, and is temporarily stopped. Therefore, immediately after the tension jaw 14 returns, the tension jaw 14 separates from the clamp jaw 15 and the gripping band is released.

Next, the tension jaw 14 and the clamp jaw 15 are moved by the tension crank 2 which follows the shape of the tension cam 23 and the band release cam 24, respectively.
1 and the clamp jaw crank 22, the tension jaw 14 and the clamp jaw 15 are returned to each other while maintaining the band release interval.

As the clamp jaw crank 22 returns, the lower end of the lower protruding piece of the clamp jaw crank 22 comes into contact with the shaft 26 via the backing plate 27 and stops, so the clamp jaw 15 acts to tighten the tension jaw 14. Waits at a predetermined position on the sliding trajectory in the direction. The tension jaw 14 then returns to its original position.

[0042]

[Effects of the Invention] Since the present invention is constructed as described above, it produces the following effects.

[0043] Since the clamp jaw of the clamp jaw arm that engages with the tension adjustment cam and waits is provided in a slidable manner on the sliding locus of the tension jaw in the tightening action direction, the band gripped by the tension jaw and the clamp jaw when tightening the band. It was possible to provide a band tightening device which smoothly grips the band without slipping and does not bite the band into the second jaw, and further allows fine adjustment of the band tightening force.

Further, when the tension jaw returns in a direction opposite to the tightening action direction, the clamp arm is engaged with the tightening adjustment cam to wait on the sliding trajectory, and the band between the tension jaw and the clamp jaw is released. Therefore, it was possible to provide a band tightening device that makes it possible to smoothly release the gripping band between the jaws after the band has been tightened.

Further, a tension crank rotated by the tension cam is rotatably provided, and the tension arm is interlocked with the tension crank so as to slide at a constant stroke through a rod, and the tension arm is connected to the tension adjustment cam through a rod. A clamp jaw crank is rotatably provided to stand by with the clamp jaw crank, and one end of the clamp jaw crank is rotatably connected to the clamp jaw arm via a rod, and the crank jaw of the clamp jaw arm is connected to the tension jaw. Since the tension jaw arm and the clamp jaw arm can be operated remotely via the rod, a space is provided around the jaw in which a band passage path and other members can be placed. Furthermore, by adjusting the rod, the position where the band is gripped by the two jaws can be finely adjusted. Further, since the tension jaw and the clamp jaw are provided with a concave portion and a convex portion that fit into each other, the grip of the band by the jaws becomes even more reliable, and the band does not slip between the jaws during tightening.

[Brief explanation of the drawing]

FIG. 1 is a front view showing a first embodiment;

FIG. 2 is a perspective view showing the first embodiment;

FIG. 3 is a perspective view showing a second embodiment;

FIG. 4 is a cross-sectional view of the main part showing the forming side of the gripping part of the jaw;

[
FIG. 5: Front view of conventional device;

FIG. 6 shows a perspective view of a conventional device.

[Brief explanation of symbols]

Claims (5)

[Claims] Claim 1: A tension arm is provided that moves in a fixed stroke by a tension cam that rotates in response to a signal in which a band surrounds an object to be packed placed on a packing machine main body, and a tension jaw provided at the end of the tension arm has a tightening action. A clamp jaw of a clamp jaw arm that engages with a tension adjustment cam and waits is provided in a sliding locus in the direction, and the clamp jaw is biased via a spring in a direction opposite to the tightening action direction of the tension jaw. . A band tightening device for a packaging machine, wherein the tension jaw grips the band between the waiting clamp jaw and is slidable in synchronization with the clamp jaw. 2. When the tension jaw returns in a direction opposite to the tightening action direction, the clamp jaw arm is engaged with the tightening adjustment cam to wait at the sliding trajectory,
2. The band tightening device for a packaging machine according to claim 1, wherein the band is released from the tension jaw and the clamp jaw. 3. A tension crank is provided which is rotated by the tension cam, and the tension arm is interlocked with the tension crank so as to slide through a constant stroke through a rod, and is engaged with the tightening adjustment cam and is on standby. A clamp jaw crank is rotatably provided, the clamp jaw arm is rotatably connected to one end of the clamp jaw crank via a rod, and the clamp jaw of the clamp jaw arm is rotated in the tightening action direction of the tension jaw. The band tightening device for a packaging machine according to claim 1, wherein the band tightening device is made to stand by on a sliding trajectory. 4. The gripping portion between the tension jaw and the clamp jaw is formed with a flat surface or an uneven portion on the tension jaw side to an extent that does not cause trouble when feeding the band, and a protrusion is carved on the clamp jaw side. A band tightening device for a packaging machine according to claim 1 or 3. 5. The band tightening device for a packaging machine according to claim 4, wherein the gripping portions of the tension jaw and the clamp jaw are respectively formed with a concave portion and a convex portion that fit into each other.