The present, invention concerns a packaging device, used to package or tie together steel plate wrapped coils, steel bundles and the like, by tying a packaging material around the surface of the item for packaging, so that the item for packaging can be easily handled and in order to prevent the item for packaging from getting dirty. Specifically, it concerns a packaging device which, on the one hand, can be used for packaging relatively large items for packaging, yet its structure is simple and can be miniaturized.

In the past, packaging devices of steel plate wrapped coils included, for example, the device disclosed in Japanese Patent Application 5-294314, which consisted of a circular track, forming a closed route, which is constructed so that one part thereof can open and close, a truck, revolving on top of the abovementioned circular route, a means of feeding a packaging material, which is mounted on the above-mentioned truck and which feed the packaging material from a packaging material coil, and a means of support, which can support the item for packaging whose one part was closed and which is set in the above-mentioned circular route.

According to the above-mentioned existing technology, as shown in, for example, Figure 3, a truck (51) is set so that it can pass inside the steel plate wrapped coil, which is the item for packaging, and while a motor (52) and a current collector (53) are mounted on the truck (51), conductive rails (55) are arranged along a circular track (54), these conductive rails (55) supply electric power, via the current collector (53), to a motor (52), and the truck (51) is thus self-run.

In addition, because the distance between the item for packaging and the truck (51), surrounding its circumference, varies from one time to another, a tension accumulator (58) is installed on the truck (51), in order to prevent slackening of the packaging material (57) delivered from the packaging material coil (56), which is on the truck (51), when this distance narrows.

In other words, several stationary guide rollers (59) and several swinging guide rollers (60) are arranged, and if the swinging guide rollers (60) move away from the stationary guide rollers (59), the packaging material (57), which revolves the guide rollers (59,60) and moves along a curved route, is slackened and thus the swinging guide rollers (60) applies a constant tension to the packaging material (57), as it moves away.

The above-mentioned existing packaging device has the following problems.

1. (1) Because a motor is installed in the truck, the truck has to be large, and in order to enable this truck to smoothly revolve, the radius of curvature in the corners has to be big, the circular track has to be big, and the whole packaging device is enlarged. In addition, because conductive rails are laid along the circular track, electrical leak counter-measures have to be sufficiently installed in order to keep the safety of the operator, and the whole packaging device is therefore enlarged also for this reason.
2. (2) In the tension accumulator, which consists of several stationary guide rollers and several swinging guide rollers, in addition to an urging means, in order for the swinging guide rollers to smoothly move, space has to be created on the truck, and the truck has to be enlarged even more. As a result, the circular track has to be enlarged and the whole packaging device is further enlarged.

In addition, although it may seem that by increasing the number of guide rollers, the movement distance of the above-mentioned swinging guide rollers can be decreased, in such a case, the resistance produced between the guide rollers and the packaging material increases, the smooth movement of the swinging guide rollers is interrupted, and especially in devices wherein the truck revolves at a high speed, they cannot respond quickly to rapid changes in the tension of the packaging material.

The present invention solves the above-mentioned problems by proposing a packaging device which can be used for packaging relatively large items for packaging, while its structure is simple and can be miniaturized.

According to a first aspect of the present invention a packaging device, is equipped with a means of feeding a packaging material, constructed so that it can feed a packaging material from a packaging material coil, which is supported so that it can rotate,

and which is characterized by the fact, that the above-mentioned packaging material coil is connected with mobility, via a torque limiter, to a drive generator, which applies a rotatory force in the direction opposite to the direction in which the packaging material is fed, so that, if the rotatory force, generated by drawing the packaging material from the packaging material coil, decreases below a set value, this packaging material coil can rotate in the opposite direction.

Since the second aspect is constructed as above, if the tension of the packaging material decreases as a result of a decrease in the length of the packaging material drawn from the packaging material coil, until it is wrapped around the item for packaging, the rotatory force produced by the drive generator is transmitted to the packaging material coil, the packaging material coil rotates in the opposite direction and applies tension to the packaging material.

On the other hand, by being wrapped around the item for packaging, a tension exceeding a set value is applied to the packaging material, drawn from the packaging material coil, and the rotatory force from the drive generator is interrupted by the rotatory force limiter, and the packaging material is thus smoothly fed from the packaging material coil. As a result, the first aspect has the following advantage.

• (A) The drive generator is connected, with mobility, to the packaging material coil and tension control rollers, via a torque limiter, and a set tension can therefore be applied to the packaging material. Therefore, there is no need to install the numerous swinging guide rollers, used in the above-mentioned past technology, and the whole packaging device can be simplified and miniaturized.
  
  According to a second aspect of the present invention a packaging device, is equipped with a means of feeding a packaging material, constructed so that it can feed a packaging material from a packaging material coil, and is characterized by the fact, that a tension control roller is installed between the packaging material coil and the item for packaging, which is wrapped by the packaging material, fed from the packaging material coil, that the tension control roller is constructed so that it can be rotated by the passage of the packaging material along the surface of the tension control roller, and that the tension control roller is connected with mobility, via a torque limiter, to a drive generator, which applies a rotatory force in the direction opposite to the direction in which the packaging material passes the above-mentioned tension control roller, so that, if the tension of the packaging material, which passed the surface of the tension control roller (14), decreases below a set value, this tension control roller can rotate in the opposite direction.
  
  Since the second aspect is constructed as above, when the packaging material, fed by from the packaging material coil, passes, a tension control roller rotates as a result of the friction with the packaging material. In addition, if the tension, applied by the packaging material as it wraps around the item for packaging, decreases below a set value, the tension control roller rotates in the opposite direction and the packaging material rewinds, causing the tension of the packaging material to be maintained over the set value. Moreover, if the tension, applied by the packaging material as it wraps around the item for packaging, exceeds a set value, the rotatory force produced by the drive generator is interrupted by the rotatory force limiter, and the packaging material is thus smoothly fed from the packaging material coil. As a result, the second aspect has the following advantage in addition to that of the first aspect.
• (B) A drive generator, which applies a rotatory force in the opposite direction, is connected with mobility via torque limiters to the tension control rollers, set between the packaging material coil and the item for packaging, and a constant tension can therefore be applied to the packaging material, regardless of the consumption of the packaging material.

The packaging devices, pertaining to the above-mentioned first and second, aspects, can be applied to packaging devices which wrap a packaging material around an item for packaging by fixing a means of feeding the packaging material and causing the item for packaging to be self-run. The packaging devices pertaining to the first and second aspects can be applied to a packaging device which causes a truck, on which the means of feeding the packaging material is mounted, to revolve along a circular track. In addition, in such a case the truck can be driven by a means of running the truck, which is set along the circular track, or the truck can be made to self-run by means of a motor, which is mounted on the truck and is supplied electricity from conductive rails, arranged along the circular track.

In addition, as the drive generator used in the packaging device pertaining to the above-mentioned first and second aspects, a drive generator for exclusively reverse rotation can be installed, but in the case that the above-mentioned means of feeding the packaging material is mounted on the truck and causes it to revolve around the circumference of the item for packaging, it is recommended to utilize this drive generator, which can cause the truck to revolve. If the truck revolution speed is increased, the changes in the distance between the packaging material coil and the item for packaging become sharp and slack can be rapidly produced. By utilizing the drive generator which causes the truck to revolve, therefore, the slack produced by the above-mentioned changes in distance can be quickly absorbed in response to the speed of the truck.

A particular embodiment of a device in accordance with this invention will now be described with reference to the accompanying drawings; in which:-

• Figure 1 is a front cutaway view of the packaging device, showing an embodiment of the present invention;
• Figure 2 is a perspective cutaway view of the truck, used in the packaging device; and
• Figure 3 is a front cutaway view of the truck, showing the past technology.

As shown in Figure 1, this packaging device (1) is equipped with a frame (3), in which a holding space for the item for packaging (2) is set, a truck (4), which revolves around the circumference of the above-mentioned holding space for the item for packaging (2), a means of feeding a packaging material (7), which feeds a packaging material (6) from a packaging material coil (5), which is mounted on the above-mentioned truck (4), and a means of support (9), which supports the steel plate wrapped coil, which is the item for packaging (8).

The above-mentioned frame (3) consists of two U-shaped half-frames (3a/3a), set so that their open sides (10) face each other, and a circular track (11), which forms a closed route, is formed along the inner rim of the front and back sides of the frame (3).

Each of the above-mentioned U-shaped half-frames (3a/3a) are made so that they can connect and disconnect, to the right and left, in Figure 1, and by connecting and disconnecting, the above-mentioned circular route (11) opens and closes in the center.

In addition, the carrying-in and carrying-out of the above-mentioned steel plate wrapped coil (8) is done with the above-mentioned circular track (11) in the open state. In the carrying-in state, shown in Figure 1, only the upper part of the steel plate wrapped coil (8) is placed in the above-mentioned circular track (11). In- other words, in a state in which the circular track (11) is inserted inside the steel plate wrapped coil (8), the steel plate wrapped coil is supported by the above mentioned means of support (9).

In addition, the circular route(11) is constructed so that it can open and close by causing the two U-shaped half-frames (3a/3a) to mutually connect and disconnect, but the circular route can also open and close by movement of only one part of the frame, such as by a parallel movement or a swinging movement, and the like.

As shown in Figures 1 and 2, in the above-mentioned U-shaped half-frame (3a), a serrated toothed belt (12), which rotates on the inner side and outside of it, is installed as a means of driving the truck. When the serrated toothed belt (12) rotates, through the work of a motor (13), it is caused to interlock with the above-mentioned truck (4), and the driving force of the serrated toothed belt (12) thus causes the truck (4) to revolve along the above-mentioned circular track (11).

The packaging material (6), fed from the above mentioned packaging material coil (5), is gradually drawn from the packaging material coil (5) as the truck revolves on the circular track (11), and after it passes the circumference of the tension control roller (14), it is wrapped around the above-mentioned steel plate wrapped coil.

The above-mentioned steel plate wrapped coil (8) is rotated and at the same time supported by the above-mentioned means of support (9), and therefore, the above-mentioned packaging material (6) spirally wraps the inside and outside of the steel plate wrapped coil (8) and the packaging is completed within one rotation of the steel plate wrapped coil (8) on the means of support (9).

As shown in Figure 2, in the above-mentioned truck (4), passive gears (16) are supported, with mobility, between two side planks (15/15), and the above-mentioned serrated toothed belt (12) engages with these passive gears (16). The above mentioned passive gears (16) are connected with mobility to driving gears (18) via transmission mechanisms (17), set on the outside of the above-mentioned side planks (15). These driving gears (18) engage with a rack, formed in the outer surface of the above-mentioned circular track (11), and the driving force of the above-mentioned serrated toothed belt (12) is transmitted from the passive gears (16) to the driving gears (18), thereby causing the truck (4) to revolve along the circular track (11).

Because the above-mentioned serrated toothed belts (12) are each set along the whole inner surface of each of the U-shaped half-frames (3a), as shown in Figure 1, if the openings (10) of both U-shaped half-frames (3a/3a) touch each other, the two serrated toothed belts (12/12) are likely to interfere with each other in the above-mentioned openings (10). In this embodiment, therefore, the serrated toothed belt (12) of one side is set, as shown in Figure 2, in a groove on one side, which is formed in the U-shaped half-frame (3a), while the other serrated toothed belt (12) is set in a groove on the opposite side, and both serrated toothed belts (12/12) do not interfere with each other. Therefore, the above-mentioned passive gears (16) are set in two places between the side planks (15/15). Nevertheless, the means of engagement are not limited to or by the structure described in this embodiment.

Moreover, in order for the truck (4) to be smoothly guided on the circular track (11), four holding rollers (20) are installed in the front and back in the inner surface of each side plank (15).

Between the above-mentioned two side planks (15/15), as the above-mentioned means of feeding the packaging material, the packaging material coil (5), tension control roller (14) and three guide rollers (21...) are supported, each with mobility, and the packaging material (6), drawn from the packaging material coil (5), passes a route which curves between the tension control roller (14) and the three guide rollers (21...) and is fed to the circumference of the steel plate wrapped coil, during which process the friction with the packaging material (6), which passes along the surface of the tension control roller (14), causes it to freely rotate.

When the above-mentioned truck (4) revolves along the circular track (11), the distance between the packaging material coil (5) and the position for wrapping the steel plate wrapped coil (8) periodically changes, but when this distance decreases, the drawing force of the packaging material (6) from the packaging material coil (5), or, in other words, the tension of the packaging material (6), weakens, and adequate wrapping cannot be conducted. Torque limiters (24/24) were therefore installed at the ends of the front side, shown in Figure 2, of the support axis (22) of the above-mentioned packaging material coil (5) and of the support axis (24) of the tension control rollers (14), each of these torque limiters (24) is connected, with mobility, to the above-mentioned passive gear (16), which becomes the drive generator (25), via the abovementioned transmission mechanism (17), so that a rotatory force in the direction opposite to the direction in which the packaging material (6) is fed and passes, can be applied by the passive gear (16) to the packaging material coil (5) and tension control roller (14).

In the case that the packaging material coil (5) and the tension control roller (14) rotate at a rotatory force which exceeds a set value, through the drawing of the packaging material (6), the above-mentioned torque limiter (24) interrupts the rotatory force produced by the drive generator (25), so that the packaging material (16) is smoothly drawn. In addition, in the case that the rotatory force, produced by the above-mentioned drawing, decreases below a set value, the interruption is removed and the rotatory force produced by the drive generator (25) is applied, the slackened packaging material (6) is rewound and the tension increased.

In addition, because the external diameter (of the packaging material coil (5)) decreases with the consumption of the packaging material (6), the rotatory force in the opposite direction, which rotates the above-mentioned packaging material coil (5) via the above-mentioned torque limiter (24), initially can only resist a small drawing force. Nevertheless, because the rotatory force in the opposite direction, which rotates the above-mentioned packaging material coil (5), is aimed at eliminating slack in the packaging material between the packaging material coil (5) and the tension control roller (14), there is no problem even when the tension changes.

On the other hand, because the external diameter of the tension control rollers (14) is constant, the rotatory force which rotates the tension control rollers (14) is not affected by the consumption of the packaging material (6), and tension higher than a predetermined one can be applied to the packaging material (6) wrapped around the steel plate wrapped coil (8).

In the above-mentioned embodiment, the explanation refers to the packaging of a steel plate wrapped coil, but, needless to say, the invention can also be applied to packaging of other items for packaging, such as steel bundles. In the case that a long steel bundle is packaged, for example, packaging can be done by spirally wrapping the packaging material, by causing the truck to revolve while the steel bundle is gradually moved in a direction perpendicular to the page.

Moreover, the mechanism which maintains the tension of the above-mentioned packaging material above a set value can be applied also in the case that the means of feeding the packaging material is stationary and the item for packaging is caused to freely rotate. However, as shown in the above-mentioned embodiment, in the case that the above-mentioned mechanism is utilized in a means of feeding the packaging material, which is mounted on a truck which revolves along a circular track, the tension of the packaging material can be maintained by a simple and compact structure, the truck can be miniaturized and the whole packaging device can be miniaturized.