Patent Grant
11613039
The present disclosure is directed to a platen having inflatable air bladders for use in a bundle breaker and to a bundle breaker including the platen, and, more specifically, to a platen having inflatable air bladders configured to directly contact sheets of material on a bundle breaker and to a bundle breaker including the platen.
Many products are manufactured in elongated sheets that can be separated into individual blanks along scored or perforated or partially cut lines. For example, corrugated paperboard blanks, from which boxes and other structures may subsequently be formed, are often formed in this manner.
An elongated sheet of corrugated paperboard may be divided by score lines into, e.g., five separate blanks. The score lines generally run transversely, that is, perpendicular to the length of the elongated sheet. When a plurality of the sheets are arranged in a stack, the score lines are aligned vertically. Such a stack of elongated sheets made up of individual blanks is sometimes referred to as a “log.” During the processing of logs, it is necessary to break individual stacks of sheets from the log along the vertically aligned score lines (sometimes referred to as a “breaking plane” or “breaking junction”). A stack of sheets that has been broken off a log may be referred to as a “bundle.” The individual portions of the log that will be broken off the log may also be referred to as “bundles” even when they are still attached to each other in the log. Therefore, a log will comprise a plurality of bundles joined together at transverse score lines which bundles can be broken off the log one at a time to form individual bundles.
Machines that receive logs and break individual bundles from the logs are known as “bundle breakers.” A bundle breaker generally includes two bottom support sections, each of which may include a conveyor, and two platens, one mounted over each support section. The downstream support section can tilt or pivot relative to the upstream support section. In operation, a log is moved along the bundle breaker until a score line between a first bundle of the log and a second bundle of the log is arranged at a junction of the first conveyor and the second conveyor, and the first bundle is then clamped against the downstream support section by the first platen and the second portion of the log is clamped against the upstream support section by the second platen. An actuator then shifts one of the support sections, usually the downstream support section, relative to the upstream support section to break the log along the score lines and separate the first bundle from the log. That first bundle is then moved away from the remaining portion of the log, and the log is shifted further downstream until the score lines separating the second bundle of the log from the third bundle of the log arrives at the breaking location at which time the process repeats until all bundles that formed the original log have been separated.
Some bundle breakers are configured to break bundles from multiple logs at the same time. That is, a plurality of logs may be arranged in parallel across the bundle breaker with the score lines separating the downstream-most bundle of each log from the rest of the respective log located at the junction of the upstream and downstream support sections. The multiple logs may be simultaneously clamped by the platens against the support sections by the first and second platens and broken simultaneously by the movement of the downstream support section relative to the upstream support section.
When multiple logs need to be broken simultaneously by the bundle breaker, it is generally desirable that all logs have the same number of elongated sheets and are thus the same height. The platens can then be moved into a predetermined position and apply the same pressure to each of the logs during the breaking process. However, it sometimes occurs that the heights of the logs are not identical. In such case, the amount of force applied against the logs by the platens must be sufficient to secure the shortest log for proper breaking. That force, however, may partially crush some of the sheets in the taller logs.
It would therefore be desirable to provide a bundle breaker that is less likely to damage bundles while they are being held in place by a movable platen, especially when the heights of the bundles differ.
These and other problems are addressed by embodiments of the present invention, a first aspect of which comprises a bundle breaker having an upstream breaking support and a downstream breaking support each having an input end and an output end, a first platen located above the upstream breaking support and a second platen located above the downstream breaking support. The first platen has a plurality of first air bladders and the second platen has a plurality of second air bladders, each of the air bladders having a bottom contact surface facing one of the breaking supports. First and second actuators are operably connected to the first and second platens and configured to shift the first and second platens toward a raised position above the respective breaking support and toward a lowered position above the respective breaking support to selectively clamp a first portion of a log between the bottom contact surfaces of the air bladders and the breaking supports. The bundle breaker also includes a third actuator configured to shift the input end of the downstream breaking support relative to the output end of the upstream breaking support from a first position to a second position to break the second portion of the log from the first portion of the log.
In addition, a method of operating this bundle breaker includes clamping a log with the bundle breaker and controlling the pressure in at least some of the air bladders to securely clamp the log and/or to avoid damage to portions of the log.
These and other aspects and features of the invention will be better understood after a reading of the following detailed description in connection with the attached drawings wherein:
Referring now to the drawings, wherein the showings are for purposes of illustrating presently preferred embodiments of the invention only and not for the purpose of limiting same,
The bundle breaker 10 includes an input conveyor 22, and the input conveyor 22 has an output section 24 connected to an input end of the upstream breaking conveyor 14 and an input section 26. The input section 26 can be raised and lowered relative to the output section 24 to allow an operator to easily pass through the bundle breaker 10 to reach the other side of the bundle breaker. The input conveyor 22 includes a continuous belt 30 supported by an input end support shaft 32, an output end support shaft 34 and a center support shaft 36, the center support shaft 36 being located at a hinged connection between the input section 26 and the output section 24. A lock bar 38 holds the input section 26 in the raised position, and a gas spring 40 helps control the transition of the input section 26 from the raised to the lowered position. The bundle breaker 10 also includes an output conveyor 29.
The input end support shaft 32 is mounted between two plates 41 which plates 41 are each slidably mounted on a pair of rods 43 and biased away from the output section 24 by a pair of springs 45. The force produced on the input end support shaft 32 maintains a suitable tension on the belt 30 during use.
The first platen 18 is connected to the frame 12 by a first platen support 46, and the second platen 20 is connected to the frame 12 by a second platen support 48. The first platen support 46 will primarily be discussed hereafter, it being understood that the second platen support 48 is substantially identical thereto. The first platen support 46 includes a bottom frame 50 to which the first platen 18 is attached, first and second side plates 52, a motor mount 54 supported by the bottom frame 50 at a location between the first and second side plates 52 and a motor 56 supported by the motor mount 54. Each of the side plates 52 has inner sides that face the motor 56 and outer sides that face away from the motor 56. Each of the side plates 52 includes a notch 58, and a drive shaft 60 extends from either side of the motor 56 through the notches 58. A drive gear 62 is mounted at each end of the drive shaft 60 on the outer sides of the side plate 52.
Referring now to
The motor 56 preferably comprises a servo gear motor having torque feedback. A servo motor available from Siemens under the brand name/model number SIMOTICS S-1FK7 is suitable for use in the present disclosure. This motor is driven electrically and can be set to apply a predetermined limit for the torque to the drive shaft 60. In this manner, the amount of downward force exerted by the first platen 18 against a log on the upstream breaking conveyor 14 beneath the first platen 18 can be controlled, and the force can be set so as not to exceed a force that would damage the individual sheets that form the log beneath the platen 18. The motor 56 controlling the second platen 20 can be controlled in the same manner. The torque limit can be selectably set by the controller C (
In one embodiment, the servo motor 56 itself monitors torque and stops moving the first platen 18 when the measured torque exceeds a predetermined level or increases faster than a predetermined rate, either of which indicates that a maximum desired force is being applied against a log on the upstream breaking conveyor 14. In other embodiments, the servo motor 56 sends a signal indicative of the amount of torque being produced by the servo motor 56 to the controller C, and the controller C sends a signal to the servo motor 56 to stop the servo motor 56 when the controller C determines that a maximum desired force is being applied against the log.
While the use of a servo motor that is capable of sensing torque is preferred, other methods can be used to determine how forcefully the first platen 18 is pressing against a log. For example, the current drawn by the servo motor 56 can be monitored, and an increase in the current to above a certain level or an increase in a rate of change of the current that exceeds a certain rate can provide an indication of how much force is being applied against the log. In addition, signals indicative of servo motor torque can be sent to the controller C which will take appropriate actions to stop the downward movement of the first or second platen 18, 20 in response to a change in the detected torque or a rate of change of a signal.
A plurality of air bladders 70 are mounted on the side of the first platen 18 that faces the upstream breaking conveyor 14 and on the side of the second platen 20 that faces the downstream breaking conveyor 16. These air bladders 70 are exposed at the bottom sides of the first and second platens 18, 20 and have exposed bladder walls 73 that form a lowermost surface of the first and second platens 18, 20 and are configured to make direct contact with the logs on the breaking conveyors beneath the first and second platens 18, 20. The air bladders 70 are connected to a source of compressed air or other gas, and all the air bladders 70 are configured to be inflated to a predetermined pressure. The pressures in subsets of the air bladders 70 may be independently controllable, and the subsets of air bladders can include one or more air bladders. For example, with reference to
As used herein, descriptions of “pressurizing” one of the air bladders 70 can include leaving the air bladder open to atmospheric pressure or drawing a vacuum to reduce the interior of an air bladder to below atmospheric pressure. That is, if a first air bladder 70 is set to a first pressure and a second air bladder 70 is set to a second, lower air pressure, the first air bladder 70 and second air bladder 70 may both be pressurized to pressures higher than ambient atmospheric pressure or the second air bladder 70 may be in fluid communication with the atmosphere or at a pressure lower than atmospheric pressure. Various configurations of the air bladders 70 are possible, and the pressures in subsets of the air bladders 70 can be controlled to improve the clamping of logs against the upstream and downstream breaking conveyors 14, 16.
For example,
When a log is positioned on the upstream and downstream breaking conveyors 14, 16 beneath the air bladders 70 of
Referring now to
When logs are to be broken along a non-linear breaking junction, it is generally desirable to allow the logs to flex for a distance around the breaking junction; that is, to not clamp the logs too close to the breaking junction. This can be accomplished by providing separately controllable, longitudinally shorter air bladders 70a near the breaking junction and leaving these shorter air bladders 70a uninflated (or inflating them to a lower pressure than the longer air bladders 70b) during a breaking operation. The longer air bladders 70b located further from the breaking junction are inflated to secure the one or more logs. Various ones of the longer air bladders 70b can also be left uninflated in order to avoid damage to the longitudinal edges of the logs as discussed above.
It is also possible to provide an array of longitudinally shorter air bladders 70, for example, as illustrated in
The bundle breaker 10 further includes a breaking motor 72 operably connected to a drive disk 74 both of which are mounted on the vertical frame members 66 of the downstream breaking conveyor 14. The breaking motor 72 is preferably also a servo gear motor with torque feedback similar or identical to the motors 56 used to raise and lower the first and second platen supports 46, 48. The downstream breaking conveyor 16 is pivotably connected to the upstream breaking conveyor 14 at a hinge 76. A connecting arm 78 is connected between a peripheral edge of the drive disk 74, and the vertical support 66 of the upstream breaking conveyor 14. The breaking motor 72 is configured to rotate the drive disk 74 from a first position illustrated in
The torque produced by the breaking motor 72 can be monitored to detect a change in the torque that indicates a break has occurred. For example, less force is required to move the drive disk 74 after a clamped bundle has been broken off a log. A drop in a detected torque to below a predetermined level can therefore be used to indicate that a break has occurred. A sudden drop in the torque produced by the breaking motor 72, detected by a sudden drop in current drawn by the breaking motor 72, for example, can also indicate that a break has occurred. The break may therefore be identified by detecting the rate at which the current changes.
Information about the surface area of the logs, which can be detected by the 2-D sensing system 80, can also be used to set a clamping pressure. Each log that arrives at the bundle breaker 10 will be scanned by the 2-D sensing system 80 to determine a height of the log and the area of the top surface of the bundle or log that will be contacted by the first platen 18 or the second platen 20. The amount of pressure applied by the first and second platens 18, 20 is directly related to the surface area of the log to be contacted by one of the platens 18, 20. That is, a greater clamping force will be applied to a bundle that has a surface area of six square feet than to a bundle having a surface area of two square feet. This is partly because the clamping force must be sufficient to compress each of the sheets in the bundle to a sufficient extent to prevent the sheets from slipping relative to each other during the breaking process while at the same time not compressing the sheets so much that they are damaged. More force is required to compress a larger surface area bundle by a given amount (by 1% of bundle height, for example) than a smaller one because a given applied force is applied over a greater surface area. A pressure-based clamping action is advantageous over a position-based clamping action because pressure-based clamping action is independent of stack height. However, to be effective, the surface area under each platen must be known. For irregular shapes, it can be difficult to determine surface area in real time. However, determining the surface area of logs, even irregularly shaped logs is possible in real-time using a fast-response 2-D sensing system. This results in a more consistent and repeatable process, which is also not easily affected by real-world imperfections, such as warped boards.
In addition, the first and second platens 18, 20 may apply a different clamping force against the bundles or portions of the log under each of the platens 18, 20. Furthermore, the force applied by each platen 18, 20 may change each time a bundle is broken from the log and the log is re-clamped. For example, if a log that has a length greater than the combined lengths of the upstream and downstream platens is moved into position in the bundle breaker with the downstream-most bundle beneath the second platen 20, the second platen 20 will make contact with the entire surface area of the downstream-most bundle. On the other hand, if the length of each bundle is less than the length of the first platen 18, the first platen 18 may contact the top surface of the bundle adjacent to the downstream-most bundle and the next adjacent bundle. That is, if a log has first through fifth bundles with the downstream-most bundle being the first bundle, the first bundle will be clamped between the downstream breaking conveyor 16 and the second platen 20, and the second bundle and a portion of the third bundle may be clamped between the upstream breaking conveyor 14 and the first platen 18. More force must be applied by the first platen 18 because that platen 18 must compress a portion of the third bundle in addition to the second bundle.
The second platen 20 will generally clamp exactly one bundle, unless that given bundle has a length greater than that of the second platen 20. However, when the only remaining bundles are the fourth and fifth bundles, each of the first and second platens 18, 20 will contact the surface area of exactly one bundle and in this case, the same clamping force will be applied by each of the first and second platens 18, 20.
A representative calculation is as follows: The downward force on each of the bundles will be set to 10 times the surface area in contact with the particular platen. For example, if the surface area of the bundle is 100 square inches, a downward pressure of 1000 lbs. will be applied to produce a pressure of 10 psi on the bundles.
After a bundle is broken from a log, the 2-D sensing system will measure the height and shape of the log to make sure that the log was not damaged during the breaking process. For example, if the height of a bundle after being broken off the log is less than a predetermined percentage of the starting height of the log, the bundle should be inspected for damage. Likewise, if the top surface of the log deviates from a plane by a predetermined amount this may suggests that an edge or corner of the bundle has been damaged. Marks on the top sheet of the bundle that were not present when the bundle entered the bundle breaker may also be detected.
The operation of the bundle breaker 10 will now be described.
Referring to
As can be seen in
The first platen support 46 and the second platen support 48 are lowered by controlling the motors 56 on the first and second platen supports 46, 48 to rotate the drive shafts 60 and cause the drive gears 62 to move along the racks 68 and thus move the first and second platen supports 46, 48 toward the logs L1, L2, L3 beneath the first and second platens 18, 20. The platen supports 46, 48 are lowered until the air bladders 70 directly contact the tallest one of the logs, in this case log L3. Because the log L3 is the tallest of the logs, the air bladders 70 above the log L3 will contact the log L3 before the remaining air bladders 70 contact the logs L2 and L1. The continued downward movement of the first and second platen supports 46, 48 will compress the air bladders 70 against the first log L3.
If the air bladders 70 are in fluid communication (except for the uninflated air bladders between the logs and/or along the edges of the logs), the compression of the air bladders 70 above the log L3 will cause the air bladders 70 above the second and third logs to expand and, with continued downward movement, the air bladders 70 will come into contact with all three logs with a substantially equal pressure present in all of the inflated air bladders 70. Alternatively, if the air bladders 70 are independently controlled, inflation of the air bladders above the tallest log L3 can be stopped while inflation of the air bladders above the shorter logs L2 and L1 can be continued until an acceptable pressure is exerted against all logs by the air bladders 70. The sensing of contact between the logs and the air bladders 70 and/or the size of any gap remaining between the air bladders 70 and the logs can be performed by the LIDAR system 80 of
The clamping force applied against the logs can be related to the air pressure in the interiors of the air bladders 70, which pressure can, in turn, be sensed by a pressure senor (not illustrated), and the downward movement of the first and second platen supports 46, 48 will continue until a predetermined clamping pressure is obtained. The desired pressure for the air bladders 70 on each of the first and second platens 18, 20 can be determined by the controller C based on information provided by the 2-D sensing system 80 in the manner described above. The controller C, upon receiving a pressure signal that the desired pressure is present in the air bladders 70, controls the motors 56 to stop the downward movement of the first and second platen supports 46, 48. If the interiors of the pressurized air bladders 70 are in fluid communication, the same pressure will be applied to each of the logs despite their different heights and substantially no pressure will be applied directly to the longitudinal edges of the logs which will not be in contact with any air bladder 70.
Alternately, a fixed pressure can be established in all the air bladders 70, or at least in the air bladders 70 that will contact a portion of a log without overlying a longitudinal edge of a log, before the clamping operation begins. Because the air bladders 70 that are pressed against the tallest log on the bundle breaker 10 will deform more than the air bladders 70 that are pressed against the shorter logs, damage to the logs will be minimized even if the pressures in the air bladders that contact a log are not adjusted based on log height.
When the score lines or weakened portions between adjacent bundles in the logs are substantially linear, the air bladders 70 that extend along the entire longitudinal length of the first and second platens 18, 20 can be used. When the short air bladders 70a and the long air bladders 70b are present as illustrated in
With the first bundles of the three logs L1, L2 and L3 clamped between the air bladders 70 of the second platen 20 and the downstream breaking conveyor 16 and the second bundles in each log clamped between the air bladders 70 of the first platen 18 and the upstream breaking conveyor 14, the controller C causes the breaking motor 72 to rotate the drive disk 74 to shift the downstream breaking conveyor 16 about the hinge 76 from the position illustrated in
Especially when the breaking motor 70 is a servo motor, the distance moved by the downstream breaking conveyor 16 can be easily controlled. That is, in some embodiments, the breaking motor may be configured to rotate the drive disk 74 by 180 degrees during each breaking operation. However, for shorter logs, that is, logs containing a smaller number of sheets, the movement of the downstream breaking conveyor 16 produced by rotating the drive disk 74 by, for example, 135 degrees, may be sufficient to perform a break. Basing the rotation angle of the drive disk 74 and thus the angle traversed by the downstream breaking conveyor 16 can reduce cycle time by avoiding moving the downstream breaking conveyor 16 further than required to complete a given break.
The torque sensing performed by the breaking motor 72 may also allow the degree of movement to be determined during each breaking operation. That is, the breaking motor 72 will apply torque to the drive disk 74 that will increase and/or vary in a certain manner until a bundle breaks from the log at which time the resistance to movement will drop suddenly. Thus instead of rotating the drive disk 74 by a predetermined angle with every break, the movement of the drive disk 74 can be terminated (and reversed to return the downstream breaking conveyor to the position shown in
After the break is complete, the breaking motor 72 reverses direction and rotates the drive disk from the position illustrated in
The present invention has been described above in terms of presently preferred embodiments. Modifications and additions to these embodiments will become apparent to persons of ordinary skill in the art upon a reading of the foregoing description. It is intended that all such modifications and additions form a part of the present invention to the extent they fall within the scope of the several claims appended hereto.
The present application claims the benefit of U.S. Provisional Patent Application No. 63/005,632, filed Apr. 6, 2020, the entire contents of which is hereby incorporated by reference.
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| Number | Date | Country | |
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| Number | Date | Country | |
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| 63005632 | Apr 2020 | US |
