Method and double endless belt for the production of coated foam boards made of a free-flowing reaction mixture.

p0001The invention relates to a method and a double conveyor belt for producing foam webs provided with surface layers of a flowable reaction mixture to a conveyor belt consisting of a lower and an upper conveyor belt laminator, which are driven uniformly.

p0002It was previously believed to be able to ensure the absolute synchronism by a common drive motor and a mechanical coupling via chain drive or gear drive.

p0003In recent years, such dual conveyor belts are getting bigger, become especially longer and be operated in the interests of efficiency to the Granze their performance with high peripheral speeds. Through the longer conveyor belts even more manufacturing tolerances of individual components add up disadvantageous circumstances and, secondly, it has been found that by heating the reaction zone by the heat rising to the upper conveyor belt usually more expanded than the lower. If the inlet zone heated and guided the lower conveyor belt through the inlet zone, so can also the lower conveyor belt having a greater elongation. During the operating period, the different expansions add on. Because on the one hand, both conveyor belts are driven at the same speed and on the other hand, there is a positive connection between the two conveyor belts on the nascent in manufacturing foam web, contact time during prolonged operation inevitably disruptions. If it is steel belts, which are driven by so-called polygon wheels, it can happen that the drag chain of the conveyor belts skip on the drive wheels from time to time. For double conveyor belts which have a drive via driver, it may happen that one of the two conveyor belts is driven only by the frictional engagement with the foam web. For double conveyor belts, which are equipped with seamless fabric belts, rubber belts or steel belts, which are driven about rolls by friction, resulting in a corresponding slip. The circulation of the conveyor belts is restless and in particular slats the panel edges often dominate in the outer layers.

p0004to have recognized Without the root cause, it has previously procedure so that one has turned the laminator after a certain time, once piled up the disturbances, for a time. The transport bands were cool back then and Renewed operation, the error rocked again for renewed disturbances.

p0005The object is to find or to improve the known double conveyor belt so that a smooth operation is ensured by any relative speed between the conveyor belts is avoided a process.

p0006This object is achieved in that the two conveyor belts mechanically decoupled, driven separately and the drive powers are thereby regulated in terms of each other exactly the same rotational speed of the conveyor belts.

p0007In this way, is compensated by different strains, production tolerances, etc. A resulting relative velocity between the two bands and by the mechanical decoupling of the drive, the physical over-determination of the system is canceled. This occurs on the nascent in manufacturing foam sheet to only a minimal power flow. The new method can be successfully applied to all mentioned in the prior art embodiments of dual conveyor belts.

p0008According to a particular embodiment of the method, both the driving power of the upper conveyor belt as well as that of the lower conveyor belt can be controlled.

p0009Alternatively, the driving power of a transport belt is kept constant and regulated that of the other conveyor belt.

p0010As control variables preferably recorded by the electric drive motors currents are used.

p0011Alternatively, are detected as control variables the drive torques.

p0012As far as it concerns conveyor belts, which are moved by means of driver and attacks, can be as a control variable and the thrust of the pressing against the stops carrier detect.

p0013The double conveyor belt for continuously producing foam webs provided with surface layers of a flowable reaction mixture proceeds from a provided with a drive upper conveyor and a lower conveyor belt.

p0014The new is the fact that each of the two conveyor belts is associated with its own, the other mechanically decoupled electric drive motor and these motors are connected to one another via a control.

p0015The regulation of the drive power is carried out in terms of each other exactly the same rotational speed of the conveyor belts.

p0016In the drawing, the new laminator is shown purely schematically in an exemplary embodiment and described in more detail below:

p0017The double conveyor belt consists of a lower conveyor belt 1 and an upper conveyor belt 2, which are driven on flight chains 3 4. the production of one in the nascent provided with cover layers 5, 6 foam sheet 7 is filled Schäumraum between the conveyor belts 1, 2nd The conveyor belts 1, 2 are guided in rails 8. 9 The flight chains 3, 4 are provided with drivers 10, 11 which engage against stops 12, 13 of the conveyor belts. 1, 2 Each gripper chain 3, 4 is a special drive 14, allocated to the 15th These actuators 14, 15 consist of an electric drive motor 16, 17, a transmission 18, 19, a clutch 20, 21 and a worm gear 22, 23, which driving with the cleated 3, 4, gear 24, 25 respectively mesh. The drive motors 16, 17 is associated with common rules 26th It consists of the only indicated measuring points 27, 28 of which via measuring lines 29, 30, the images taken by the drive motors 16, 17 currents I₁ and I₂ are given to the controller 31st From this, the drive motors 16, 17 via measuring lines 32, 33 and indicated actuators 34, 35 controlled in the sense of a constant ratio of the power consumption. The exact synchronization between the upper and lower band is achieved by the force fit on the foam sheet. The forces occurring in the foam sheet are minimized by the predetermined distribution of driving power.

p0018In the event that you want to take the drive torque as a control variable, its commitment to the measuring point 27, 18 respectively to the output shaft of the drive motor 16, 17th

p0019In the embodiment of the double conveyor belt shown in the drawing one can use also the force acting on the carriers 10, 11 on the stops 12, 13 force as control variable. One must then at least on a driver 10, 11 or at least one stop 12, 13 of each conveyor belt 1, 2 as a load cell measuring point 27, 28 provide. Nevertheless, as in particular thermal expansions of the conveyor belts plenty slowly noticeable enough one measuring point per conveyor, since only one measurement per revolution needs to take place.