A DEVICE AT MULTI-PLATEN PRESSES

Abstract: A device at multi-platen presses (11) which with a loading elevator (12) by means of a pusher (14) simultaneously transfers a number of transport plates (15) loaded with stampings (17) to the press (11) which after the press operations are unloaded by means of an extractor (16) to an unloading elevator (13). The purpose is to prevent breakdowns and to automize the pushing-in and unloading of the transport plates, whereby it shall be able to stop the pushing-in or the unloading. These tasks have been solved in that the pusher (14) and/or the extractor (16) are provided with said means (22, 29), shaped as sensors of a number at least corresponding to the number of transport plates (15), which sensors are arranged to sense every separate transport plate regarding its pushing-in and withdrawal resistance resp., and that each sensor (22, 29) is arranged to activate an alarm device and/or a stop device, which stops the continued movement of the pusher or the extractor resp. when a certain force maximum is exceeded.

Description: A DEVICE AT MULTI PLATEN PRESSES The present invention refers to a device at mu ti platen presses of the type in which a number of transport plates carrying stampings by means of a pusher are transferred simultaneously from a loading elevator to the press, and which after a stamping operation by means of an extractor are transferred therefrom to an unloading elevator, whereby the device incorporates means, which at occurance of an abnormal resistance during the transfer of the transport plates interrupt the movement of the pusher. BACKGROUND OF THE INVENTION At production of wallboard, particle board and the like, the wood fibres and the wooden chips resp. are shaped under high pressure and elevated temperature in a press, in which a number of boards commonly are pressed at the same time. The loading of those multi platen presses is effected by means of a loading ele . vϊator, which is so designed that the entire package of transport plates, upon which the stampings are situated, are displaced by the pusher into the press. This consists of a number of pressing plates, which are displaceable vertically in relation to each other and which at loading of the press are opened so much that the transport plates can be well inserted between the pressing plates. Hitherto it has been difficult to automatize the loading of the press, as the risk for breakdowns could not been excluded. The reason for breakdown can be e.g. that the loading elevator due to an incorrect level indication has a wrong level relative to the levels of the press, thus that when the transport plates are pushed in, one or more of them will not find an opening between the pressing plates and become deformed, both at contact against the press and against the pusher. Such a breakdown means a stoppage of several hours. Another reason causing breakdown is that one or more transport plates has any type of deformity, thus that the plate, when pushe d in, will catch and is cockled, which if it happens outside the press also can influence adjacent transport plates in the elevator. If the breakdown takes place inside the press it is possible that the pressing plates are damaged. Another reason can be that the sieve on the transport plate comes loose from the transport plate and at the insertion is rolled up together with the stamping, whereby one or more heating plates are disformed. Also at the extraction of the transport plates from the press by means of the extractor to the unloading elevator it is possible that breakdowns may occur. The pulling member at the transport plate can e.g. be disformed thus that the extractor will not seize it whereby the transport plate will remain in the press. It may also occur that the transport plate certainly is withdrawn -from the press at the unloading, but that the stamping has got stuck on the underside of the press plate and will not -follow the transport plate out of the press . Tfcfέ PURPOSE AND MOST ESSENTIAL FEATURES OF THE INVENTION The purpose of the present invention is to prevent breakdowns of abovementioned type without manual supervision. Another purpose of the invention is to make possible that the pushing in and extraction of the transport plates can be carried out fully automatically with simple but reliable means, which immediately shall stop a pushing in or unloading even if the separate plate only is slighted disformed. This objects have been solved therein that the pusher and/or the extractor are provided with said means, shaped as sensors of a number at least corresponding to the number of transport plates, which sensors are arranged to sense every separate transport plate regarding its pushing-in and withdrawl resistance resp. , and that each sensor is arranged to activate an alarm device and/or. a stop device, which stops the continued movement of the pusher or the extractor resp. when a certain force maximum is exceeded. OISCRIPTION OF THE DRAWINGS Fig. 1 shows a side view, partly in section, of a multi platen press with an loading elevator, provided with the device according to the invention, Fig. 2 shows in smaller scale a view from above of the press, the loading and unloading elevators and a pusher and extractor serving these elevators, Fig. 3 shows in bigger scale a side view partly in section of the sensor of the pusher, Fig. 4 shows schematically a side view of the pulling out end of a transport plate with devices for sensing the stampings on a transport plate. DESCRIPTION OF EMBODIMENT In fig. 2 is shown a conventional wet press 11 at one side of which is. connected a loading elevator 12 and at the other side of which a"n unloading elevator 13, which elevators are both U-shaped in cross-section and designed thus that a pusher 14, which is movable along horizontal guides above the loading elevator, can push out all transport plates 15 situated on different loading elevator levels into the press 11 , whereas on the unloading side a corresponding extractor can pull out the plates 15 from the press and into the unloading elevator 13. The loading and unloading elevators are inside the shanks of the U provided with shelf planes, on which the transport plates 15 with the stampings 17 are placed. If the stamping e.g. is a wet sheet at production of wallboards , then at the transfer of the wet sheet 17 to the transport plate 15, the sieve 18 will also be located on the transport plate. The pusher 14, which is displaceable in the horizontal plane along guides 19, is equipped with at least one vertical beam 20, which at conventional plants transfers the pushing force of the pusher 14 directly to the transport plate 15. In order to prevent breakdowns when pushing in the transport plates 15 into the press 11 between the opened platens 21 , the vertical beam 20 is provided with a pressure sensor 22 just in front of a transport plate 15, which during the time a plate is pushed in senses the resistance presented by a plate at the pushing- in operation. If the plate should get stuck anywhere on the way or should a resistance increase occur in any other way, the sensor immediately will initiate an alarm and/or stop the continued movement of the pusher when a preset treshold value is exceeded. In order to be able to adjust the sensor 22 in relation to the pusher and in relation to the loading elevator 12, a cushion 23 is arranged in front of each sensor 22, which cushion consists of two sleeves 24 and 25, which can be screwed into each other and which are provided with an end plate 26 and 27 each, said sleeves being displaceable in a guide 28 attached to the beam 20. By screwing the sleeves 24. 25 in relation to each other it is possible to adjust the positions of the cushions 23. On the opposite side of the press 11 the extractor 13 can be equipped with similar sensors 29, which via a yoke is actuatable by gripping claws 30 of a number corresponding to the number of transport plates 15, which gripping claws are displaceably supported at the extractor 13 and arranged to grip a hook 31 on the corresponding transport plate 15. Also in this case the sensor 29 releases an alarm and/or causes the extractor to stop immediately, at a pressure increase caused by the transport plate and giving a bigger resistance than the preset treshold value. As it can occur that the stamping gets stuck in the press against the lower side of a pressure plate 21 there is arranged sensors 32 also on the unloading elevator 11 , which sensors e.g. can be a sliding contact, which senses if the stamping 17 remains on the transport plate 15 or not. The sliding contact can be fed with a low tension current, e.g. 24V, whereby the transport plate via the press as mass (earth) is connected in a current circuit. When the transport plate hits the sliding contact it is indicated that all plates are withdrawn. Contact is not obtained if any plate should remain in the press and alarm and/or an immediate stop of the extractor is released. After the initial withdrawl of the transport plate from the press, whereby the current circuit is closed, in that the sliding contact engages the transport plate, the current circuit is interrupted in that the stamping 17 lifts the sliding contact from the transport plate or breakes the current. If this does not happen an alarm is released and/or the continued movement of the extractor is stopped, at the same time as a display (not shown) indicates which transport plate it concerns. Instead of electric sensing it is also possible to use a microswitch as sensor, which interrupts a current circuit, when the switch indicates a level difference as the stamping passes by the switch. The invention is not limited to the embodiment described and shown but a plurality of variations are possible within the scope of the claims.

Claims: CLAIMS 1. A device at multi platen presses (11 ) of the type in which a number of transport plates (15) carrying stampings ( 17 ) by means of a pusher (14) are transferred simultaneously from a loading elevator (12) to the press (11) , and which after a stamping operation by means of an extractor (16) are transferred therefrom to an unloading elevator (13) , whereby the device incorporates means, which at occurance σ-f an abnormal resistance during the transfer of the transport plates interrupt the movement of the pusher, c h a r a c t e r i z e d t h e r e i n , that the pusher (14) and/or the extractor (16) are provided with said means (22,29), shaped as sensors of a number at least corresponding to the number of transport plates (15) , which sensors are arranged to sense every separate transport plate regarding its pushing-in and withdrawl resistance resp. , and that each sensor (22,29) is arranged to activate an alarm device and/or a stop device, which stops the continued movement of the pusher or the extractor resp. when a certain force maximum is exceeded. 2. A device according to claim 1 , c h a r a c t e r i z e d t h e r e i n , that said means incorporate also sensor (32), e.g. a sliding contact, for each transport plate (15) , which sensors are arranged to sense that the plate is carried along at the withdrawl of the transport plates (15) from the press (11 ), and that the stamping is located on the transport plate and has not become stuck in the press, whereby the transport plates are arranged to form part of the current circuit of the sensor, which circuit is closed when the sliding contact rests against the transport plate and is interrupted at contact with the stamping.

Inventors: OESTMAN CARL-OLOF, OESTMAN, CARL-OLOF
Applicants: SWANBOARD MASONITE AB
Application year: 1986
Main classification: B27N3
IPC codes: B27N3, B30B7