EP4514724A1

EP4514724A1 - Pulp bale conveyor system and a method for controlling a pulp bale conveyor system

Info

Publication number: EP4514724A1
Application number: EP23716380.3A
Authority: EP
Inventors: Tobias LÖÖF; Stefan NORDHÄLLING; Claes ÅKERLUND
Original assignee: Valmet Oy; Valmet AB
Current assignee: Valmet Technologies Oy; Valmet AB
Priority date: 2022-04-26
Filing date: 2023-04-03
Publication date: 2025-03-05
Also published as: WO2023211328A1; CN119095780A

Abstract

The invention relates to a pulp bale conveyor system (1) comprising a pulp bale conveyor (2) comprising at least one beam (4), at least one endless chain (6) mounted on said beam, a motor unit (10) operatively connected to said chain, and a chain tensioning device (16) comprising a tensioning member (24) comprising a curved surface (24a), which tensioning member is slidably arranged, and a spring (30; 51) operatively connected to said tensioning member to urge said tensioning member in a chain tensioning direction. The system also comprises a position sensor (101) configured to measure or detect a position of the tensioning member (24) a control unit (100) configured to receive, in processing circuitry, information indicative of the position of the tensioning member (24) from the position sensor (101), and determine, in processing circuitry, if adjustment of the pulp bale conveyor (2) is needed based at least on the received information. The invention also relates to a method for controlling the pulp bale conveyor system (1).

Description

PULP BALE CONVEYOR SYSTEM AND A METHOD FOR CONTROLLING A PULP BALE CONVEYOR SYSTEM

TECHNICAL FIELD

The invention relates to a pulp bale conveyor system for conveying pulp bales. The invention also relates to a method for controlling a pulp bale conveyor system according to the invention.

BACKGROUND

Cellulose pulp is generally and delivered to an operator in the form of pressed pulp bales.

The pulp bales are transported on conveyors between different baling process stages, e.g., pressing, stacking, wrapping and binding, before they are offloaded and transported to the operator. A conveyor usually comprises a conveyor frame comprising two to four parallel beams. Each beam is provided with an endless chain slidably mounted on the beam to move the bales along the beam. Each chain is trained on rotatable sprockets arranged at a distance from one another in the longitudinal direction of a beam and one of said rotatable sprockets is operatively connected to a drive shaft driven by a motor. The drive shaft is operatively connected to a plurality of rotatable sprockets on different parallel beams, so that there is no speed difference between the chains on said beams.

A pulp bale usually weighs at least 200 kg and a conveyor may convey more than one pulp bale at a time. Thus, a large torque is required to move the pulp bales along the conveyor. This torque imparts tension to the chains, which gradually become slacker. Therefore, each chain is fitted with a manually operated chain tensioning device arranged to ensure that a suitable tension is applied to said chain.

One problem associated with known chain tensioning devices is that the force applied by the chain tensioning device has to be adjusted at regular intervals due to slackening of the chain.

Another problem is that it is difficult to adjust the chain tensioning device so that a suitable tension is applied to the chain. A chain that is too tight will cause premature wearing of the chain and sprockets, whereas a slack chain may jump of the sprockets or come into contact with other components, and the pulp bales may not be correctly positioned on the pulp bale conveyor.

OBJECT OF THE INVENTION

A first object of the invention to provide a pulp bale conveyor and a pulp bale conveyor system that solves the above defined problems.

A second object of the invention is to provide a method for controlling a pulp bale conveyor system that solves the above defined problems.

SUMMARY

The first object is achieved by means of a pulp bale conveyor system as defined in the independent claim.

A pulp bale conveyor system comprises a pulp bale conveyor comprising at least two elongate beams. Each beam extends from a first end to a second end along a longitudinal axis of the beam. Each beam has an endless chain mounted thereon for transporting pulp bales along the longitudinal axis of the beam. The pulp bales may be conveyed in any direction along the length of the beam. The chain is mounted on guiding members, e.g., rotatably mounted wheels, positioned at a distance from one another along the longitudinal axis of the beam, so that the chain extends along a chain path around at least a portion of the beam. A motor unit is arranged to move the chain along the chain path. The pulp bale conveyor further comprises a chain tensioning device comprising a tensioning member comprising a curved surface configured to engage with said chain, which tensioning member is slidably arranged in said chain tensioning device, and a spring operatively connected to said tensioning member to urge said tensioning member in a chain tensioning direction to impart tension to said chain.

The pulp bale conveyor system also comprises a position sensor configured to provide information indicative of the position of the tensioning member and a control unit configured to receive said information from the position sensor. The control unit is further configured to use this information to determine when it is time to adjust the pulp bale conveyor by e.g. shortening the chain and/or when it is time to tension the spring.

Furthermore, the control unit can be configured to use said information from the position sensor to determine the extension of the chain and to determine the wear of the chain and/or the tension in the chain.

Thus, the chain tensioning device comprises at least one position sensor configured to provide information indicative of the position of the tensioning member. The position of the tensioning member is indicative of the extension of the chain and this information can be used, possibly in combination with other additional data, e.g., characteristics of the chain and/or spring such as arrangement, dimensions, extensibility, and compression rate and/or extension rate, to determine the wear of and the tension in the chain and in extension when it is time to shorten the chain and/or when it is time to tension the spring.

A tensioning member is in this context defined as a movable member that is movable to engage with and exert a force on a chain. The chain tensioning direction is the direction of movement of the tensioning member when it is urged towards the chain to impart tension to the chain.

Gradual slackening of the chain is countered by the spring, which continuously urges the tensioning member in a chain tensioning direction and thus ensures that the tension in the chain is maintained within a suitable interval for a longer period of time compared to prior art devices. The suitable interval depends on several factors, for example, dimensions and strength of the chain. Thus, the time interval between consecutive manual adjustments of the tensioning device is extended and productivity is improved. The risk that the chain will jump of the wheels or sprockets or come into contact with other objects is reduced and positioning of the pulp bales on the pulp bale conveyor is improved. The chain tensioning device according to the invention is easy to use and there is no need to apply an excessive force to the spring because the tension applied to the chain is continually adjusted during use by means of the spring. Thus, the risk that the chain will be tensioned too tight is reduced and premature wearing of chain and guiding members, e.g., wheels and sprockets, is avoided. A tensioner is defined as a device arranged to provide tension to the chain. The tensioner comprises the tensioning member and the spring and a frame connecting the tensioning member and the spring. The tensioner is part of the chain tensioning device and parts of it are movable in relation to other parts of the chain tensioning device.

The tensioning member is movable from a first position to a second position and may be positioned anywhere between the first and second position. Regardless of the position of the tensioning member, a tensioning force is imparted on the chain. The position of the tensioning member is determined by the tension in the chain and the force applied by the spring.

The chain tensioning device may also comprise a locking mechanism. A locking mechanism is a device that essentially prevents the tensioning member from moving against the chain tensioning direction during use. The tensioning member may, for example, be urged against the chain tensioning direction when the chain is jerked. Minor movements against the chain tensioning direction may be allowed depending on the design of the locking mechanism.

The locking mechanism may have any suitable design. In one embodiment, the locking mechanism comprises a first part that moves with the tensioning member and a second part that does not move with the tensioning member. One or both of the first and second parts may be pivotably mounted. One of the first and second parts may comprise a toothed edge or surface provided with teeth and the other part comprises a cog arranged to engage with said teeth to prevent movement of the tensioning member against the chain tensioning direction. Each tooth may have an angled surface configured so that the cog may slide across the tooth as the tensioning member is moved in the chain tensioning direction and an opposite stop surface arranged to engage with said cog so that the cog prevents backwards movement of the tensioning member when the tensioning member is urged against the tensioning direction.

In another embodiment, the first part of the locking mechanism is pivotally connected to a movable part of the tensioner and provided with a through hole arranged to receive an elongate rod fixedly connected to a non-movable part of the chain tensioning device. In this embodiment, the rod constitutes the second part of the locking mechanism. During use, the first part is urged towards a locking position, in which an inner surface of the first part, which inner surface defines the outer perimeter of the through hole, engages with an outer surface of the rod and prevents movement of the stop member against the chain tensioning direction. The first part may be urged towards the locking position by means of a spring mechanism or by means of gravity acting on a portion of the first part located on the opposite side of the position where the first part is pivotally connected to the movable part of the tensioner in relation to an opposite portion of the first part comprising the through hole.

The tensioning member may have any suitable shape as long as it comprises a curved convex surface configured to engage with the chain. The tensioning member may be rotatably mounted in the chain tensioning device or nonrotatable. Advantageously, the tensioning member comprises a rotatably mounted wheel and the curved surface extends around the perimeter of the wheel and is provided with teeth arranged to mesh with said chain. This feature ensures that the chain does not move sideways or jump off the wheel during use. Alternatively, the surface may be smooth and the chain may slide along the surface as it is moved along the chain path.

The chain tensioning device may comprise at least one guiding member for guiding the chain along the chain path. The guiding member comprises a curved surface configured to engage with the chain and is arranged in relation to the tensioning member so that the chain path extends through on an arc with an angle of at least 90 degrees, preferably at least 135 degrees and most preferably at least 165 degrees around said tensioning member, when the tensioning member is in the second position. The guiding member may have any suitable shape as long as it has a convex curved surface configured to engage with the chain. The guiding member may be fixed or rotatably mounted in the chain tensioning device. Advantageously, the guiding member comprises a rotatably mounted wheel and the curved surface extends around a perimeter of the wheel and is provided with teeth arranged to mesh with the chain. This feature ensures that the chain does not move sideways or jumps of the wheel during use. Alternatively, the surface may be smooth and the chain may slide along the surface as it moves along the chain path. The chain tensioning device may comprise any suitable number of guiding members arranged to guide the chain along the chain path. Tensioning of the chain increases when the tensioning member is moved by the spring in the tensioning direction, that is, away from the first position and towards the second position. Maximum tensioning of the chain is achieved when the tensioning member pulls on the chain on both sides of the tensioning member. This means that maximum tensioning is achieved when the chain extends 180 degrees around the tensioning member. One advantage with this embodiment is that the chain tensioning device can be made more compact because the required movement of the tensioning member to achieve a certain tension in the chain is reduced.

Advantageously, at least one guiding member or tensioning member in the chain tensioning device is mounted on a drive shaft operatively connected to the motor unit, so that the guiding member or tensioning member is driven by the motor unit and moves the chain along the chain path. This arrangement allows for a more compact design of the pulp bale conveyor in comparison to a design wherein the driven wheel is separate from the chain tensioning device. The drive shaft is suitably connected to corresponding guiding members or tensioning members on adjacent beams within the same pulp bale conveyor, so that the chains on all beams in the pulp bale conveyor move with the same speed.

The spring may be of any suitable type of spring, including mechanical springs, such as a coil spring, and gas springs. The spring may be a compression spring or an extension spring. A compression spring is compressed when the spring is loaded and exerts a pushing force on the tensioning member in the chain tensioning direction, which pushing force is countered by an opposite force exerted by the chain on the tensioning member. An extension spring is stretched when the spring is loaded and exerts a pulling force on the tensioning member in the chain tensioning direction, which pulling force is countered by an opposite force exerted by the chain on the tensioning member. Consequently, a compression spring and an extension spring are arranged on opposite sides of the tensioning member.

In some embodiments, the spring may extend in a longitudinal direction from a first and to a second end, which first end is arranged to be moved relative said second end during tensioning of the spring. The chain tensioning device may further comprise a first tension indicator positionally fixed in relation to and operatively connected to and movable with said first end of the spring and a second tension indicator positionally fixed in relation to the second end of the spring, wherein said first tension indicator is arranged in relation to said second tension indicator so that a suitable initial tension of said spring is achieved during tensioning of said spring when said first tension indicator is adjacent to said second tension indicator. This arrangement makes it easy for an operator to ensure that an appropriate tension is applied to the spring, i.e. , that the chain is not too slack or too tight after tensioning of the spring. This feature ensures that the time interval between consecutive spring tensioning actions and/or shortenings of the chain is extended.

The first tension indicator may have any suitable shape. Advantageously, it has an elongate shape and extends from a first end to a second end. The first end of the first tension indicator is connected to the first end of the spring, either directly or by means of a connecting member, and the second end of the first tension indicator is used to determine when the tension in the spring has reached a suitable level. A suitable tension in the spring is achieved when the second end of the first tension indicator is moved to a position adjacent to the second tension indicator. The first tension indicator may, for example, be an elongate rod or an elongate cylinder arranged around the spring and extending along at least a portion of the length of the spring.

Advantageously, the chain tensioning device comprises a third tension indicator fixed in positional relation to the second end of said spring and positioned to indicate that the tension in the chain needs to be (manually) adjusted. The third tension indicator may be a marking positioned so that the first tension indicator is close to the third tension indicator when tensioning of the chain is required. Manual adjustment of the tension in the chain can be achieved by shortening the chain by removal of one or more chain links and/or by adjustment of the compression or extension of the spring (depending on spring type). Alternatively, the third tension indicator may be an electronic or mechanical switch arranged to interact with a movable part of the tensioner when the movable part has reached a position that indicates that tensioning of the chain is required. The switch may be arranged to activate a warning device, e.g., a warning light, when tensioning of the chain is required. Advantageously, the operator selects a spring with suitable characteristics, e.g., extension rate, compression rate and/or strength, to ensure that a suitable tension is applied to the chain when the spring is loaded and that the time intervals between consecutive manual spring tensioning actions and/or shortenings of the chain is maximized.

In some embodiments, the tensioning member is slidably mounted in at least one elongated slot in the chain tensioning device. This includes embodiments wherein the tensioning member is mounted on a shaft extending into said slot and movable along said at least one slot. The slot extends in the chain tensioning direction. Advantageously, the tensioning member is positioned between two parallel panels, each provided with an elongate slot, and the tensioning member is mounted on a shaft that extends into said slots.

Advantageously, the various parts of the chain tensioning device, e.g., the slots, are dimensioned and the characteristics of the spring, e.g., length, compression rate and/or extension rate, are chosen such that the chain does not have to be shortened (by removal of some links) to increase tension in the chain before the chain is worn out and must be substituted.

The chain tensioning device may be arranged on either side of a beam. The chain tensioning device may comprise a mounting member arranged to be attached to the beam. The mounting member may, for example, be one of the above mentioned panels arranged on either side of the tensioning member. The chain tensioning device is suitably attached to the beam in such a way that the various components of the chain tensioning device, e.g., the spring and the tensioning member, are easily accessible to an operator. Advantageously, the chain tensioning device is attached to an outer side of a beam facing away from other beams in the pulp bale conveyor. Advantageously, the chain tensioning device is attached to the beam between the first and second ends of the beam along the longitudinal axis of the beam.

The control unit may be configured to use additional data to determine these parameters. These data may be stored in a data storage unit connected to or integrated with the control unit. The data storage unit may for example comprise data related to the characteristics of the chain and/or the spring, such as dimensions, extensibility, compression rate, and extension rate, and data related to arrangements and dimensions of various parts of the chain tensioning device, such as the tensioning member and the guiding members.

The control unit may be configured to provide a warning signal when tensioning of the spring and/or shortening of the chain is required. These warnings may, for example, be provided in the form of audio and/or visual signals. Visual signals may be shown on a display operatively connected to the control unit, for example in the form of a text message or a warning indicator, or via other optical means, for example a warning light.

The second object of the invention is achieved with a method for controlling a pulp bale conveyor system according to the appended independent claim.

The method comprises the steps of measuring at least one parameter indicative of the position of the tensioning member by means of at least one position sensor, transmitting information relating to the position of the tensioning member from said position sensor to a control unit, and said control unit using processing circuitry comprising a computer program and said information to determine when it is time so shorten the chain and/or tension the spring.

The processing circuitry comprising the computer program may use additional relevant data stored within the control unit or in a data storage unit connected to the control unit to determine the wear of the chain and/or the tension in the chain. Examples of additional relevant data are characteristics of the chain and/or spring such as dimensions, extensibility, compression rate, and extension rate and arrangement and dimensions of other parts of the chain tensioning device.

Determination of wear of and tension in the chain has several advantages. The risk of the chain breaking during use is reduced and maintaining a tension in the chain within a suitable interval ensures that there is no or little slackening of the chain. Manual workload and material costs can be reduced, the risk of human error is reduced and there is no need for an operator to tension the chain too tight because the control unit will inform the operator when the chain is slackening. The time intervals between tensioning actions and shortening of the chain are also extended, which further reduces production costs.

Advantageously, the method comprises the step of said control unit providing a warning signal when it is time to shorten the chain and/or when it is time to tension the spring. The warning signal may be an audio and/or visual signals and may be shown on a display of an output device operatively connected to the control unit, for example in the form of a text message or a warning indicator, via other optical means of the output device, for example a warning light, or any other suitable operator interface. This feature ensures that an operator is made aware of a potential problem.

The features of the embodiments described above are combinable in any practically realizable way to form embodiments having combinations of these features.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described with reference to the drawings, wherein: figure 1 is a schematic illustration of an embodiment of a pulp bale conveyor system according to the invention; figure 2a is a schematic illustration of a chain tensioning device in the pulp bale conveyor system in figure 1 ; figure 2b is a schematic illustration of a position sensor and a control unit in the pulp bale conveyor system in figure 1 ; figures 3 and 4 are detailed views of the chain tensioning device in figure 2; figure 5 is a schematic illustration of an alternative embodiment of a chain tensioning device according to the invention; figure 6 is a schematic illustration of an alternative embodiment of a locking mechanism according to the invention; and figure 7 is a schematic illustration of the method according to the invention.

DETAILED DESCRIPTION Embodiments of the invention are discussed below with reference to the figures. Those skilled in the art will readily appreciate that the detailed description given herein with respect to these figures is for explanatory purposes and that the invention extends beyond these limited embodiments.

Figure 1 is a schematic illustration of a pulp bale conveyor system 1 according to a first embodiment of the invention. The pulp bale conveyor system 1 comprises a pulp bale conveyor 2 configured to convey pulp bales between two stages in a baling process. A pulp bale conveyor system may comprise any number of pulp bale conveyors. However, figure 1 shows only one pulp bale conveyor 2 for the sake of clarity.

The pulp bale conveyor 2 comprises a conveyor frame 3 with two parallel beams 4. In other embodiments, the conveyor frame may comprise more than two beams. Each beam 4 has a respective endless chain 6 mounted thereon to convey the pulp bales along the length of the beam 4. The chain 6 is mounted on guiding members 7 in the form of rotatable wheels or sprockets positioned at a first and a second end of the beam 4 along a longitudinal axis of the beam. The path the chain 6 travels is referred to as the chain path. A motor unit 10 is operatively connected to the chain 6 to move the chain along the chain path.

A pulp bale weighs at least 200 kg, so a large force is required to pull the chain 6 along the chain path. This force imparts tension on the chain 6 and therefore the chain slackens over time. A slack chain 6 may jump off guiding members 7 or come into contact with other components of the pulp bale conveyor 2. A slack chain 6 may also cause a pulp bale to be incorrectly positioned on the pulp bale conveyor 2. To avoid slackening of the chain 6, each beam has a chain tensioning device 16 mounted thereon, which chain tensioning device 16 is configured to apply tension to the chain 6. A chain tensioning device 16 may positioned on an outside of a beam 4, i.e., the side of the beam 4 facing away from the other beam, or on the inside of the beam 4, i.e., the side of the beam 4 facing the other beam.

Figure 1 also discloses a control unit 100 that may be arranged in connection with the chain tensioning device 16 or at any other suitable location in connection with or operatively connected to the pulp bale conveyor 2, as will be described in more detail below with reference to Figure 2b.

Figure 2a is a schematic illustration of the chain tensioning device 16. The chain tensioning device 16 comprises an inner panel 21 a and an outer panel 21 b (shown with dashed lines) arranged in parallel at a distance from one another along a transverse direction of the chain tensioning device 16, so that a space is formed between them. The inner and outer panels 21a, 21 b are connected to one another by means of connecting members 20. The outer panel 21 b is mounted on the beam 4 in figure 1 .

The chain tensioning device 16 further comprises a tensioning member 24 in the form of a rotatably mounted wheel arranged within the space between the inner and outer panels 21 a, 21 b. The tensioning member 24 has a convex surface 24a that extends along the perimeter of the tensioning member and is provided with a plurality of teeth arranged to mesh with the chain 6 (shown with dashed lines), which runs in between the inner and outer panels 21 b, 21 b, so that the tensioning member 24 rotates when the chain 6 moves along the chain path. The tensioning member 24 is rotatably mounted on a shaft that extends through a through hole at the centre of the tensioning member 24 and further into parallel slots 28 formed in the inner and outer panels 21a, 21 b. The slots extend along the longitudinal axis of the chain tensioning device 16. The shaft is movable within the slots 28, so that the tensioning member 24 is movable along the slots 28 in a chain tensioning direction, from a first position to a second position.

The chain tensioning device 16 further comprises a first and a second guiding member 25, 26 in the form of rotatably mounted wheels positioned between the inner and outer panels 21 a, 21 b. The first and second guiding members 25, 26 are positioned after the tensioning member 24 along the chain path. Each guiding member 25, 26 comprises a convex surface 25a, 26a that extends along the perimeter of the respective guiding member 25, 26 and is provided with teeth arranged to mesh with the chain 6, so that the first and second guiding members 25, 26 rotate with the chain 6 as the chain is moved along the chain path. The first guiding member 25 is mounted on a drive shaft that is operatively connected to the motor unit 10 (see figure 1 ), so that the first guiding member 25 transmits a drive torque to the chain 6 to move the chain along the chain path. The chain 6 can be moved in a forward or reverse direction. The first guiding member 25 is positioned below the first guiding member and in a position relative the first guiding member 25 along the longitudinal axis of the chain tensioning device 16 so that the chain 6 extends through an arc with an angle of at least 135 degrees around the tensioning member 24 when the tensioning member 24 is in its second position. This arrangement ensures that more tension is applied to the chain 6 for each movement of the tensioning member 24 towards its second position.

The second guiding member 26 is positioned vertically in level with the tensioning member 24 and forward of the tensioning member 24 along the longitudinal axis of the chain tensioning device 16.

Now referring to figure 2b, the pulp bale conveyor system comprises a sensor 101 (schematically shown and also disclosed in figure 2a) arranged to provide information indicative of the position of the tensioning member 24 to the control unit 100 (schematically shown). This information is indicative of the distance the tensioning member 24 has been moved in the chain tensioning direction and can be used by the control unit 100 to determine, by means of processing circuitry 102 comprising a computer program, the tension in the chain 6 and/or the wear of the chain 6.

The control unit 100 is thus configured to receive, in processing circuitry 102, information indicative of the position of the tensioning member 24 from the position sensor 101 , and to determine, in processing circuitry 102, if adjustment of the pulp bale conveyor 2 is needed based at least on the received information.

Adjustment of the pulp bale conveyor 2 is defined herein as tensioning the spring 30 and/or shortening the chain 6, or alternatively as replacing the chain 6.

The control unit is further preferably configured to determine if adjustment of the pulp bale conveyor is needed based also on additional data. Such additional data may include dimensions and other characteristics of the spring and chain, e.g., compression rate, extension rate, tensile strength etc. These data may be stored in a data storage unit 103 connected to or integrated with the control unit 100.

Also, in some embodiments the position sensor 101 is configured to measure or detect the position of the tensioning member 24 to continuously provide information. Similarly, the control unit 100 is configured to continuously receive information indicative of the position of the tensioning member 24 from the position sensor 101 and to continuously use said information to determine when it is time to tension the spring 30 and/or shorten the chain 6 to adjust the pulp bale conveyor 2.

The term “continuously” is used herein to mean “repeatedly”, i.e. to denote repeated operation at desired intervals. Such desired intervals may be 1 second, 1 minute or 1 hour, for instance, or a combination thereof. Also, the desired intervals may be regular intervals or may alternatively be intervals that vary. Thus, that the position sensor measures the position of the tensioning member 24 to continuously provide information is to be understood as the position sensor 101 repeatedly measuring the position of the tensioning member 24. Also, that the control unit 100 continuously receives information from the sensor 101 is to be understood as repeatedly receiving this information, and to continuously use said information is to be understood as repeating the step of determining if adjustment of the pulp bale conveyor 2 is needed.

In some embodiments, the control unit 100 is also configured to generate, in processing circuitry 102, a warning signal if adjustment of the pulp bale conveyor 2 is needed, and to present, in an output device 104 said warning signal as an audio and/or visual signal to prompt an operator to adjust the pulp bale conveyor 2.

The control unit 100 may also be configured to use the information from the position sensor 101 to determine other parameters of interest, such as when it is time to shorten the chain 6 by removing some of the links in the chain and/or when it is time to tension the spring 30 in the chain tensioning device 16. The control unit 100 may as mentioned above use additional data for this purpose, such as dimensions and other characteristics of the spring and chain, e.g., compression rate, extension rate, tensile strength etc. These data may be stored in a data storage unit 103 connected to or integrated with the control unit 100. The control unit 100 may be configured to use the processing circuitry comprising a computer program to provide a warning signal when tensioning of the spring 30 is required and/or when shortening or substitution of the chain 6 is required. These warnings may, for example, be provided in the form of audio and/or visual signals. Visual signals may be shown on a display of the output device 104 operatively connected to the processing circuitry 102 of the control unit 100, for example in the form of a text message or a warning indicator, or via other optical means, for example a warning light (not shown).

The control unit 100 may be a unit mounted on or connected to the pulp bale conveyor 2 and comprising the processing circuitry 102 and optionally also the data storage unit 103 or the output device 104. Alternatively, the control unit 100 may be distributed throughout the pulp bale conveyor system 1 or may be a remote unit that is operatively connected to the pulp bale conveyor 2 so that signals from the position sensor 101 are received in the control unit 100. Furthermore, the position sensor 101 may include a transmitter for transmitting signals to the control unit, or alternatively the transmitter may be a separate component that is operatively connected to the position sensor 101 . Alternatively, the position sensor 101 may have a wired connection to the control unit 100.

One advantage with this arrangement is that the operator is informed when action is required, and it minimizes the risk of chain brake and slackening of the chain 6. It also enables automatization and digitalization of the chain tensioning process.

Figure 3 shows a movable tensioner 34 comprising the tensioning member 24 and a spring 30 in the form of a coil spring arranged to urge the tensioning member 24 in a direction towards its second position. The tensioner 34 also comprises a frame 37 comprising two parallel arms 37a, 37b at one end connected to the shaft on opposite sides of the tensioning member 24 and at the other end connected by a connecting segment 36. The spring 30 is arranged to abut against the connecting segment 36 to urge the frame 37 and the tensioning member 24 in the chain tensioning direction to impart tension to the chain. An elongate rod 38 arranged to extend along the longitudinal axis of the spring tensioning device 16 extends through the spring 30 and the connecting segment 36 and is fixedly attached to the inner and outer panels (se figure 2) by means of a mounting member 22. The arms 37a, 37b extend through slots in the mounting member 22 so that they may be moved along the longitudinal axis of the spring tensioning device 16. The spring 30 is mounted on the rod 38 between the connecting segment 36 and a connecting member 33 mounted on the rod 38. The rod 38 extends through a central hole in the connecting member 33 so that the connecting member 33 can be moved along the length of the rod 38. Two nuts 32 with threaded inner surfaces are mounted on a threaded portion of the rod 38 on the opposite side of the connecting member 33 in relation to the spring 30. An operator may tighten the nuts 32 so that the nuts come to bear against the connecting member 33 and urge the connecting member 33 towards the spring 30 to impart tension to the spring 30.

The spring 30 will impart a tensioning force to the chain via the tensioning member 24. The chain 6 is extended during use and when this happens the spring 30 will move the tensioning member 24 within the slots 28 (see figure 2) towards the chain 6 so that the tensioning member 24 continues to impart tension to the chain 6, thus preventing slackening of the chain 6.

Now referring to figure 4, the tensioner 34 comprises a first tension indicator 35a. The first tension indicator 35a is an elongate cylinder arranged around and extending in parallel with a portion of the spring 30. The first tension indicator 35a is at a first end connected to the connecting member 33, so that the first tension indicator moves with the first end of the spring 30 towards the connecting segment 36 when a compression force is applied to the spring 30. The pulp bale conveyor 2 also comprises a second tension indicator 35b, which in this embodiment constitutes a surface of the connecting segment 36, which surface is arranged to abut against a second end of the spring 30. The characteristics of the spring 30 and the length of the first tension indicator 35a are chosen so that a suitable tensioning force is applied to the chain 6 when a second end of the first tension indicator 35a, which second end is distal from the connecting member 33, is near or adjacent to the second tension indicator 35b. The second tension indicator 35b may be of any suitable type, e.g., another part of the chain tensioning device or a visual mark on the chain tensioning device, positioned so that it is easy for the operator to determine when a suitable tensioning force is applied to the spring 30. The first tension indicator 35a may also have alternative designs. The first tension indicator may for example be an elongate rod connected to the connecting member 33 and extending along a portion of the length of the spring 30.

The spring tensioning device 16 also comprises a third tension indicator 35c in the form of an end surface of one of the arms 37b of the frame 37, which end surface faces the connecting member 33. The second tension indicator 35b is moved away from the second end of the first tension indicator 35a when the spring 30 is extended during use. Extension of the spring 30 reduces the tension applied to the chain 6 (see figure 2) by the tensioning member 24. At some point, the tension applied by the spring 30 must be increased to ensure that the tension in the chain is maintained within the suitable interval, and the third tension indicator 35c is positioned so that the second end of the first tension indicator 35a is aligned with the third tension indicator 35c when manual adjustment of the tension in the chain is required. The operator may remove some of the links in the chain to shorten the chain before the chain tensioning procedure is repeated.

Returning to figure 3, the tensioner 34 comprises a first part 41 of a locking mechanism 40 that essentially prevents the tensioning member 24 from moving against the chain tensioning direction, something that otherwise may occur when the chain is jerked. The first part 41 of the locking mechanism 40 has the form of an elongate and curved plate, which at a first end is pivotally connected to the connecting segment 36 by means of two fasteners 43. The fasteners 43 are arranged on an upper surface of the connecting segment 36 on opposite sides of the first part 41 of the locking mechanism 40. The first part 41 of the locking mechanism 40 is at an opposite second end provided with a through hole 45 adapted to receive the rod 38, which constitutes the second part of the locking mechanism 40. The fasteners 43 and the first end of the first part 41 of the locking mechanism 40 is configured so that the first part 41 of the locking mechanism may pivot somewhat around a transverse axis that extends through the fasteners 43. This pivotal mounting allows the first part 41 to be forced by a spring (not shown) towards a locking position, wherein the through hole 45 extends at an angle in relation to the longitudinal axis of the rod 38, so that an inner surface of the first part 41 of the locking mechanism 40, which inner surface defines the through hole 45, engages with the rod 38, which prevents movement of the tensioner 34 against the chain tensioning direction. It is possible to manually force the first part 41 of the locking mechanism away from the locking position to release the rod 38.

Figure 5 is a schematic view of another embodiment of a chain tensioning device 16 according to the invention, wherein in like numerals are employed to designate like parts throughout.

The basic principle is the same as for the chain tensioning device 16 in figure 2. A chain 6 extends partway around a tensioning member 24 and a tensioner 34 comprising a spring (not shown) is arranged to urge the tensioning member 24 in a chain tensioning direction to impart tension in the chain 6. One difference between the embodiments in figures 2 and 5 is that the spring in figure 5 is an extension spring arranged to exert a pulling force on the tensioning member 24. Therefore, the tensioner 34 including the spring is arranged on the opposite side of the tensioning member 24 along the longitudinal axis of the chain tensioning device 16 in comparison to the arrangement in figure 1 .

Another difference between the embodiments in figures 2 and 5 is the design of the locking mechanism 50. The locking mechanism 50 in figure 5 comprises a first part 52 pivotally mounted in the spring tensioning device 16 and operatively connected to the second end of the spring 52 in the tensioner 34. The first part 52 of the locking mechanism 50 comprises a convex surface 52a provided with teeth. A second part 53 of the locking mechanism 50 is at one end pivotally mounted in the chain tensioning device 16 and at an opposite end provided with a cog 53a configured to interact with the teeth on the convex surface 52a of the first part 52 of the locking mechanism 50 to prevent movement of the tensioning member 24 in a direction opposite to the chain tensioning direction. For this purpose, each tooth has an inclined surface on the side facing the spring 51 , so that the cog 53a may slide over the teeth when the tensioning member 24 is pulled in the chain tensioning direction, and an opposite stop surface facing away from the spring 51 and extending essentially perpendicularly to the convex surface 52a, which stop surface is configured to prevent the cog 53a from sliding over the tooth when the tensioning member 24 is pushed against the chain tensioning direction. Figure 6 shows an embodiment of a locking mechanism 60 suitable for use in the chain tensioning device 16 in figure 5. In this embodiment the locking mechanism 60 comprises a second part 62 comprising a toothed surface 62a facing the spring 51 , which toothed surface 62a is provided with teeth. A first part 61 of the locking mechanism 60 is connected to the frame 37 that connects the tensioning member 24 and the spring 51 . The first member 61 of the locking mechanism 60 extends along a portion of the length of the spring 51 between the spring 51 and the second member 62 of the locking mechanism 60. The first member 61 comprises a cog 61 a facing the toothed surface 62a of the second member 62, which cog 61 a is configured to interact with the teeth on the toothed surface 62a to prevent movement of the tensioning member 24 against the chain tensioning direction.

The method according to the invention will now be described with reference to Fig. 7 disclosing measuring 1001 at least one parameter indicative of the position of the tensioning member 24 by means of at least one position sensor 101 . The method also discloses receiving 1002, in processing circuitry 102, information indicative of the position of the tensioning member 24 from the position sensor 101 , and determining 1003, in processing circuitry 102, if adjustment of the pulp bale conveyor 2 is needed based at least on the received information.

Optionally, the step of determining 1003 if adjustment of the pulp bale conveyor 2 is needed may also be based on additional data stored in the control unit 100 or available to the control unit 100.

The method may also optionally comprise repeating the steps of the method continuously.

In optional step 1004, the method may comprise generating, in processing circuitry 102, a warning signal if adjustment of the pulp bale conveyor (2) is needed, and in optional step 1005 presenting, in an output device 104 said warning signal as an audio and/or visual signal to prompt an operator to adjust the pulp bale conveyor 2.

Adjustment of the pulp bale conveyor according to the method comprises tensioning the spring 30 and/or shortening of the chain 6 and/or replacement of the chain 6. The operator is preferably prompted by the warning signal to perform one or more of these actions.

It is generally advantageous if the control unit 100 is configured to effect the abovedescribed procedure in an automatic manner by executing a computer program. Therefore, the control unit 100 may include the memory unit 123, i.e. non-volatile data carrier, storing the computer program, which, in turn, contains software for making processing circuitry 102 in the form of at least one processor in the control unit 100 execute the actions mentioned in this disclosure when the computer program is run on the at least one processor. In one or more embodiment, the invention may therefore comprise a computer program loadable into a non-volatile data carrier communicatively connected to a processor, the computer program comprising software for executing the method according any of the method embodiments presented in connection with Fig. 7 when the computer program is run on the processor. Furthermore, the invention may comprise a non-volatile data carrier containing the computer program.

The description above and the appended drawings are to be considered as non-limiting examples of the invention. The person skilled in the art realizes that several changes and modifications may be made within the scope of the invention. The scope of protection is determined by the appended patent claims.

Claims

1 . Pulp bale conveyor system (1 ) for conveying bales of cellulosic pulp, which pulp bale conveyor system comprises:

- a pulp bale conveyor (2) comprising:

- at least one beam (4);

- at least one endless chain (6) mounted on said beam (4) for transporting said bales along a longitudinal axis of said beam (4);

- a motor unit (10) operatively connected to said chain (6) to drive said chain (6); and

- a chain tensioning device (16) comprising:

- a tensioning member (24) comprising a curved surface (24a) configured to engage with said chain (6), which tensioning member (24) is slidably arranged in said chain tensioning device (16); and

- a spring (30; 51 ) operatively connected to said tensioning member (24) to urge said tensioning member (24) in a chain tensioning direction to impart tension to said chain (6), and wherein the pulp bale conveyor system (1 ) further comprises:

- a position sensor (101 ) configured to measure or detect a position of the tensioning member (24);

- a control unit (100) configured to receive, in processing circuitry, information indicative of the position of the tensioning member (24) from the position sensor (101 ), and determine, in processing circuitry, if adjustment of the pulp bale conveyor (2) is needed based at least on the received information.

2. Pulp bale conveyor system (1 ) according to claim 1 , wherein the control unit (100) is further configured to determine if adjustment of the pulp bale conveyor (2) is needed based also on additional data. Pulp bale conveyor system (1 ) according to claim 1 or 2, wherein adjustment of the pulp bale conveyor (2) comprises tensioning the spring (30) and/or shortening of the chain (6) and/or replacement of the chain (6). Pulp bale conveyor system (1 ) according to any preceding claim, wherein the position sensor (101 ) is configured to measure or detect the position of the tensioning member (24) to continuously provide information, and/or wherein the control unit (100) is configured to continuously receive information indicative of the position of the tensioning member (24) from the position sensor (101 ) and to continuously use said information to determine when it is time to tension the spring (30) and/or shorten the chain (6) to adjust the pulp bale conveyor (2). Pulp bale conveyor system (1 ) according to any preceding claim, wherein said control unit (100) is configured to

- generate, in processing circuitry, a warning signal if adjustment of the pulp bale conveyor (2) is needed, and to

- present, in an output device (104), said warning signal as an audio and/or visual signal to prompt an operator to adjust the pulp bale conveyor (2). Pulp bale conveyor system (1 ) according to any preceding claim, wherein said chain tensioning device (16) of the pulp bale conveyor (2) comprises a locking mechanism (40; 50; 60) that prevents the tensioning member (24) from moving against the chain tensioning direction. Pulp bale conveyor system (1 ) according to any preceding claim, wherein said tensioning member (24) of the pulp bale conveyor (2) comprises a rotatably mounted wheel with a perimeter provided with teeth arranged to mesh with said chain (6). Pulp bale conveyor system (1 ) according to any of the preceding claims, wherein said tensioning member (24) of the pulp bale conveyor (2) is movable from a first position to a second position by means of said spring (30; 51 ), and wherein said chain tensioning device (16) comprises at least one guiding member (25, 26) comprising a curved surface (25a, 26a) configured to engage with said chain (6), which guiding member (25, 26) is arranged in relation to said tensioning member (24) so that said chain path extends through on an arc with an angle of at least 90 degrees, preferably at least 135 degrees and most preferably at least 165 degrees around said tensioning member (24), when the tensioning member (24) is in the second position. Pulp bale conveyor system (1 ) according to any of the preceding claims, wherein said spring (30) of the pulp bale conveyor (2) extends in a longitudinal direction from a first end to a second end, wherein said chain tensioning device (16) comprises a first tension indicator (35a) fixed in positional relation to and moveable with said first end of said spring (30), and wherein said chain tensioning device (16) comprises a second tension indicator (35b) fixed in positional relation to the second end of said spring (30), and wherein a suitable initial tension of said spring (30) is achieved when said first tension indicator (35a) is close to said second tension indicator (35b). Pulp bale conveyor system (1 ) according to claim 9, wherein said chain tensioning device (16) of the pulp bale conveyor (2) comprises a third tension indicator (35b) fixed in positional relation to the second end of said spring (30) and positioned so that manual adjustment of the tension in the chain (6) is required when said first tension indicator (35a) is at or close to said third tension indicator (35c). Pulp bale conveyor system (1 ) according to any of the preceding claims, wherein said tensioning member (24) of the pulp bale conveyor (2) is slidably mounted in elongated slots (28) in the chain tensioning device (16). Method for controlling a pulp bale conveyor system (1 ) according to any of the preceding claims, which method comprises the steps of:

- measuring at least one parameter indicative of the position of the tensioning member (24) by means of at least one position sensor (101 );

- receiving, in processing circuitry, information indicative of the position of the tensioning member (24) from the position sensor (101 ), and - determining, in processing circuitry, if adjustment of the pulp bale conveyor (2) is needed based at least on the received information. Method according to claim 12, further comprising determining if adjustment of the pulp bale conveyor (2) is needed based also on additional data. Method according to claim 12 or 13, wherein adjustment of the pulp bale conveyor (2) comprises tensioning the spring (30) and/or shortening of the chain (6) and/or replacement of the chain (6). Method according to any of claims 12-14, further comprising repeating the method, preferably repeating the method continuously. Method according to any of claims 12-14, further comprising:

- generating, in processing circuitry, a warning signal if adjustment of the pulp bale conveyor (2) is needed, and

- present, in an output device (104) said warning signal as an audio and/or visual signal to prompt an operator to adjust the pulp bale conveyor (2).