Device at multi platen presses

A loading elevator for a multi-platen press is provided with a pusher which simultaneously transfers a number of transport plates loaded with stampings to the press. After press operations are completed, the plates are unloaded by an extractor to an unloading elevator. The pushing and the unloading of the plates are automatic, with sensors provided to halt the loading and unloading in the event of excessive resistance to the movement of any one of the plates. A plurality of sensors are provided in the pusher and in the extractor, one sensor there for each of the plates. Each sensor is connected to halt the operation on recognition by the sensor that an express resistance exists and if desired to provide a signal that the halting has taken place. At the unloading elevator, a sliding contact at each of the plates senses that the plate has been moved to the unloading elevator, and the sliding contact is separated from the plate by the stamping carried on the plate, which senses thereby that the plate and the stamping upon it have both been transported to the unloading elevator.

The present invention refers to a device at multi 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 elevator, 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 of breakdowns could not be 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 
pushed in, will catch and is cocked, 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 
deformed. 
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 deformed 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. 
THE PURPOSE AND MOST ESSENTIAL FEATURES OF THE INVENTION 
The purpose of the present invention is to prevent breakdowns of the 
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 deformed. These 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 
respectively, 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 respectively when a certain force maximum is exceeded.

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 an 
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 threshold 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 16 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 16 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 threshold 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 13, 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. 24 V, 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 
breaks 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.