DRYER WITH A CONVEYOR SYSTEM FOR CONVEYING BOARDS TO BE DRIED

Description

[0001] The invention relates to a dryer with a conveyor system for conveying panels to be dried according to the preamble of patent claim 1.

[0002] A conveyor system transports boards to be dried, such as plasterboard, veneer boards, wood fiber boards, mineral wool, rock wool, or glass wool boards, through a dryer. Plasterboard essentially consists of a gypsum core, which is wrapped in cardboard on both its surface and lengthwise. Two cardboard panels (top and bottom boards) are glued together around the gypsum core.

[0003] EP 1 232 371 B1 discloses a dryer according to the preamble of patent claim 1. This dryer has conveyors arranged in tiers, each conveyor being designed as a roller conveyor. The drive system consists of a plurality of endless chains.

[0004] The dryer, for example, consists of drying chambers, fields, or sections of equal length, which are repeated in a similar or identical manner in the direction the boards pass through. The dryer is a continuous dryer, from which the boards, especially plasterboards, leave as dried boards after passing through it.

[0005] From DE 10 2009 059 822 B4 a dryer for drying panels is known in which the panels are guided in tiers through the drying chambers, whereby the panels are brought into contact with drying air by means of impact jet ventilation and whereby the impact jet ventilation is ensured by means of cross-ventilated nozzle boxes.

[0006] In the low-temperature range, i.e., at temperatures of 150°C or less, especially at temperatures below 100°C, nozzle boxes for targeted impingement jet aeration are not required because there is no risk of uneven drying and the boards cannot be damaged by uneven drying at these temperatures. For this reason, the use of nozzle boxes in a low-temperature dryer is not necessary; it is sufficient to ventilate the boards to be dried with warm air in the longitudinal or transverse direction.

[0007] The advantage of low-temperature drying is that it can be ideally combined with heat exchangers or other concepts for utilizing warm air. Low-temperature drying is often implemented in conjunction with environmentally or energy-saving measures. The reason for this is that the low temperatures allow low-calorific heat sources to be used for energy generation. Examples include solar collectors or process exhaust air from other plant components, which are used very efficiently in this area.

[0008] Wallboards are particularly suitable for low-temperature drying. For this application, the dryer is typically cross-ventilated. Flat panels, such as plasterboard, are dried horizontally.

[0009] The object of the invention is to create a compact conveying system for a low-temperature dryer.

[0010] According to the invention, this object is achieved as stated in claim 1.

[0011] Because the drying time of the boards to be dried, in particular the plasterboards, is extended several times, the invention creates a system for drying the plasterboards which allows a larger number of plasterboards per room unit to be dried and transported compared to the prior art.

[0012] For this purpose, a drive system is created that is adapted to a dryer operating at low temperature and to the large number of panels, in particular plasterboard panels, that are processed in the low-temperature dryer simultaneously over a large number of levels, for example forty to sixty levels.

[0013] By using a high number of floors in conjunction with the drive system according to the invention, a longer residence time of the boards, in particular of the plasterboards, in a low-temperature dryer can be achieved with the same dryer length as in a high-temperature dryer.

[0014] Advantageous further developments of the invention emerge from the subclaims and the description, in particular in conjunction with the drawings.

[0015] It is advantageous to design the dryer in which, in the case of a single chain, this chain overlaps the levels of the respective field in a zigzag or meander shape.

[0016] Each chain is equipped with at least one drive motor; in the case of a long chain length, two or more drive motors can be provided, as is known from EP 1 232 371 B1.

[0017] In a further advantageous embodiment, if a plurality of chains are present in each field of the dryer, two support rollers located next to each other on a level are driven by a single chain spanning the levels.

[0018] Preferably, the chains are electronically synchronized with each other within each field - and furthermore preferably over the entire length of the dryer, for example via a radio connection, for example according to the master-slave principle or by means of an incremental encoder; preferably, motors with frequency converters are used; alternatively, the chains are driven jointly via a mother chain.

[0019] It is advantageous that the mother chain is driven by at least one drive motor.

[0020] It is also advantageous if the chains are guided over chain guide rails.

[0021] If the dryer is used as a low-temperature dryer at temperatures below 150°C, the support rollers are mounted on rolling bearings. Graphite-based plain bearings, which are required for high-temperature dryers, are not needed. In addition, rolling bearings have lower coefficients of friction than plain bearings. In this case, the support roller is preferably mounted with internal rolling bearings. The axle remains stationary during operation, and only the support roller shell rotates together with the sprocket. Alternatively, the bearings can also be mounted externally of the support roller. In this case, flange bearing units must be used, and the shaft must also rotate. If internal bearings are used, a through axle must be used. Another variant is the use of shaft journals at both roller ends. In this case, the bearings are arranged externally, for example.However, it turns out that the production of support rollers with a continuous axle is simpler. The greater material requirements of the continuous axle are negligible. Therefore, support rollers with a continuous axle and internal bearings are preferred according to the invention.

[0022] The rolling bearings are preferably designed as ball bearings, deep groove ball bearings or needle roller and cage bearings.

[0023] It is also advantageous if a chain tensioning device is arranged for each chain or at least for each mother chain.

[0024] The chain tensioning device is preferably mounted in a hanging position.

[0025] According to the invention, a roller conveyor is used because it can be designed very compactly. This makes horizontal transport of the boards to be dried possible using a roller conveyor with driven support rollers.

[0026] Therefore, support rollers with the smallest possible diameter are preferred. Support rollers with internal bearings and a continuous axle, especially with deep groove ball bearings, are particularly preferred.

[0027] To ensure all the rollers rotate evenly, the power must be transferred from a central power source (motor, etc.) to all the rollers. The chain drive is located on one side of the rollers.

[0028] The invention is explained in more detail below using exemplary embodiments. They show: Fig. 1 is a side view of a field of a dryer on the drive side, wherein the roller conveyors of the field are driven by a single chain, Fig. 2 is a side view of a field of a dryer on the drive side, wherein the roller conveyors of the field are driven by a plurality of chains, which in turn are driven by a mother chain, and Fig. 3 is a longitudinal section of the bearing of a support roller of a roller conveyor.

[0029] According to the invention, two alternatives are implemented for the chain guide.

[0030] In a first variant, support rollers 1 ( Fig. 1 ) as a roller conveyor of a complete field 2 of a dryer, each driven by a single chain 3 spanning all levels of field 2 by means of a motor 4, which is preferably a geared motor. The chain 3 is additionally guided over deflection wheels 5 to 8. A tensioning device 9 is preferably present in each chain 3 of the fields 3; an arrangement for lubricating the chain 3 is preferably also provided. The levels each extend above the support rollers 1, which are located at the same height.

[0031] In a second variant, the support rollers 1 ( Fig. 2 ) of a field 2 is driven by a plurality of chains 10. Power is transmitted by means of a mother chain 11 to several chains 10 acting as output chains. Each of the chains 10 must be individually tensioned and lubricated; therefore, appropriate tensioning and lubricating devices (not shown here) are provided. The mother chain 11 is centrally driven by a single motor, for example, a geared motor (not shown here). Both the chains 10 and the mother chain 11 are deflected by deflection wheels 5, 6; 12, 13. Interconnected sprocket pairs 11a each transmit the drive force of the mother chain 11 to the chains 10.

[0032] At the Fig. 2 In the illustrated embodiment, the mother chain 11 can be used and scaled either for a single field of the dryer or for a plurality of fields. This means that, if necessary, a larger mother chain can be used, which drives the output chains in several fields. In this case, fewer gear motors are required per dryer. The chain forces in the output chains and deflection sprockets are relatively low. Advantageously, in both variants according to Fig. 1 and Fig. 2 Chain guide rails are used to keep chains 3, 10, 11 in their tracks.

[0033] In order to tension the chains 3, 10, 11, they run, for example, over a chain wheel that is loosely mounted on an axle that is movable in a vertically extending slot, wherein the chain 3, 10, 11 is re-tensioned by a weight hanging from the axle on both sides of the chain wheel. For this purpose, a tensioning device is used, for example, as is known from EP 1 232 371 B1 and in Fig. 1 is provided with the reference number 12.

[0034] Each section of the low-temperature dryer is equipped with a steel frame as a supporting structure, which also supports the conveyor system. The supporting structure includes several steel profiles as primary and secondary beams. The supporting structure, in turn, is mounted on a foundation.

[0035] According to the invention, in the event of a defect, in particular a blockage of the dryer with plasterboard, it is possible to remove the plasterboards layer by layer on the non-drive side of the dryer.

[0036] Preferably, the support rollers are mounted within a level of a field of the dryer in such a way that they have a fixed bearing on their drive side and a loose bearing on the non-drive side.

[0037] The roller conveyor according to the invention has, for example, forty tiers, which have a tier spacing of up to 100 mm, for example, and are designed for two adjacently conveyed webs of boards to be dried. However, more webs of plasterboard can also be transported side by side simultaneously in a correspondingly wider dryer. This results in a minimum dryer length of, for example, 25 bays, which corresponds to a length of 60 m, in order to achieve the required production output. One tier of the roller conveyor consists, for example, of seven driven support rollers on one level. The support rollers have, for example, an outer diameter of 60 mm; it is also not excluded that non-driven support rollers may also be present between driven support rollers.The support rollers are designed to cover the entire width of the adjacently conveyed plates and feature a continuous axle and internal bearings. Furthermore, an axle support is preferably used in the center.

[0038] All levels are mounted on dedicated supports in a fixed / loose bearing design. Vertical beams made of folded metal sheets serve as supports on the drive side. These are attached to the main girders of the scaffolding via two additional sheets. Keyhole-shaped recesses (fixed bearings) are provided in the vertical beams. On the non-drive side, longitudinal beams are used for each level and are attached to the main girders via elongated holes. The longitudinal beams have recesses into which the axles of the support rollers can be inserted (loose bearings).

[0039] The roller conveyor is driven, for example, by a spur gear motor. The gear motor transmits the power to a main chain, which in turn transmits the power to, for example, two output chains. The output chains are chains that each drive three or four rows of support rollers. The support rollers are driven tangentially.

[0040] In another design, the drives of several fields are driven by a mother chain.

[0041] As from Figur 3As can be seen, the support rollers 1 are provided at their ends with pins 14, which are rotatably mounted in roller supports 15. On the drive side, a sprocket 16 is located in front of the roller supports 15 on each pin 14. An endless chain 3 is guided over these sprockets 16 in such a way that it simultaneously drives the rollers 1 of a larger number of levels. For this purpose, the chain 3 is guided over associated sprockets 16 in such a way that the chain 3 is supported, for example, by a plate 17 and a guide rail fixed thereto.

Claims

1. Dryer with a conveyor system comprising a plurality of fields (2) extending one behind the other in the conveying direction for conveying panels to be dried, which pass through in a plurality of levels per field (2), with conveying devices arranged in the levels and designed as roller conveyors (1), with a drive system comprising a plurality of endless chains (3, 10, 11), each chain (3, 10, 11) being assigned at least one drive, characterized in that the roller conveyors (1) of all levels of a respective field (2) are drivable by means of at least one single chain (3) which spans over the levels of the respective field (2).

2. Dryer according to claim 1, characterized in that in the case of a single chain (3) per field or for a plurality of fields (2), it spans the levels of the respective field (2) or plurality of fields (2) in a zigzag or meandering pattern.

3. Dryer according to claim 2, characterized in that the chain (3) is equipped with at least one drive motor.

4. Dryer according to claim 1, characterized in that, in the case of a plurality of chains (3) per field (2), two support rollers (1) adjacent to each other on one level are driven by a single chain (3) extending over the levels.

5. Dryer according to claim 3, characterized in that the chains (3) per field (2) can be synchronized with each other by means of a radio connection or that the chains (10) have a common drive via a master chain (11).

6. Dryer according to claim 5, characterized in that the master chain (11) is driven by at least one drive motor.

7. Dryer according to one of claims 1 to 6, characterized in that the chains (3, 10, 11) are guided by chain guide rails.

8. Dryer according to any of claims 1 to 7, characterized in that the dryer is suitable for use as a low-temperature dryer at temperatures below 150°C and that the support rollers are mounted on roller bearings.

9. Dryer according to claim 8, characterized in that the roller bearings are designed as ball bearings, deep groove ball bearings or needle roller bearings.

10. Dryer according to one of claims 1 to 9, characterized in that one chain tensioning device is arranged for each chain (3, 10, 11) or at least for each master chain (11).

11. Dryer according to one of claims 1 to 10, characterized in that the chain tensioning device is suspended.