Presses – With additional treatment of material – Heating – cooling – or drying
Reexamination Certificate
1999-03-17
2001-02-20
Vo, Peter (Department: 3721)
Presses
With additional treatment of material
Heating, cooling, or drying
C100S211000, C100S309000, C156S583500
Reexamination Certificate
active
06189445
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a heating arrangement for an installation producing corrugated cardboard. More particularly, the heating arrangement includes several heating plates arranged successively in the direction of movement of a corrugated cardboard web and at least one pressure unit consisting of a bearing, arranged diagonally with respect to the direction of advance of the corrugated cardboard web at which at least one pressure element is attached.
Such a device in an installation producing corrugated cardboard has the task of drying glue between superposed webs, that is, one-sided corrugated cardboard webs and finally the cover web.
For this purpose, a known arrangement has heating plates which are heated, for example, with the vapor of a thermo-oil. With the aid of a pressure unit and its driven lower belt, a conveyor belt moves the corrugated cardboard webs to be glued along the surface of the heating plates. Load elements press the corrugated cardboard webs against the surfaces of the heating plates in order to achieve an appropriate contact of the corrugated cardboard web with the heating plate surface, that is, in order to achieve a good heat transfer toward the gluing line.
As pressure units, several systems are known. For example, pressure units may use tension rollers, a pressure hood operating with compressed air, elements which rest directly on the conveyor belt due to their own weight, or plates which are pressed against the conveyor belt by means of a spring force.
When pressure hoods such as that shown in European Patent Publication 0 412 255 A1 are used, an additional energy output for the compressed air is necessary in order to press the pressure hood onto the corrugated cardboard web. Furthermore, a certain noise level occurs in the drying area. Moreover, heat energy is unnecessarily transported and the adjustment of the working width is costly.
In the case of systems where elements press with their own weight on the belt, such as shown in European Patent publication 0 559 181 A1, no damping effect is present so that significant dynamic forces can occur. The load elements are at a relatively great distance from the friction surface so that the friction moment can become relatively great. Moreover, the load elements are subjected to a tendency toward turning which may lead to a deterioration of uniform surface contact with the heating plate surface.
The state of the art also includes to a pressure unit in which lower plates are pressured via compressed air chambers, as shown in U.S. Pat. No. 5,526,739. The construction of this known device is costly and the device also has the disadvantage that the pressure is not uniformly applied.
Canadian Patent No. 2,179,921 shows a pressure unit in the form of a load plate which consists of several units extending along the corrugated cardboard web. With this system, the corrugated cardboard web is pressured directly, possibly resulting in undesirable damage.
Another known pressure unit uses tension rollers which are attached via intermediate levers at a bearing arranged diagonally with respect to the direction of advance of the corrugated cardboard web as shown in U.S. Pat. No. 5,632,830. However, uniform pressure on the corrugated cardboard web is not assured with this system.
Moreover, in the case of pressure units with tension rollers, the rollers must not cause any jolts, oscillations or vibrations which could damage the corrugated cardboard web. During operation, it is also necessary for the tension rollers and the heating plates to be almost perfectly level so that an appropriate contact of the corrugated cardboard web and the heating plates can be realized.
From the state of the art on which the present invention is based, European Patent publication 0 623 459 B1 shows a system in which a spring force is applied to plates. This system also uses a conveyor belt. Each pressure plate is mounted to a rigid traverse via a double-jointed lever system, so that the pressure plate undergoes a plane, parallel movement. The pressure plate is pressured via spring elements.
With this known system, it is disadvantageous that the pressure plate is not always aligned parallel with the heating surface due to possible mounting deviations and/or unevennesses of the heating surface. An additional disadvantage is that the spring deflection and therefore also the pressing force change with variation of the corrugated cardboard thickness. It is necessary to adjust the tension of each pressure plate in accordance with the corrugated cardboard type used.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a corrugated cardboard facility heating arrangement with a pressure unit which prevents the above-mentioned disadvantages and is capable of pressuring the corrugated cardboard web evenly and in a safely functioning manner involving minimal construction.
In accordance with the invention, this object is accomplished with a pressure element connected with the bearing in a freely movable manner at least via one elastic medium or element, and with the bearing freely resting on the pressure element via the elastic medium with its own weight. Due to the possibility for free movement of the pressure element in all degrees of freedom, the result is the advantage of a uniform pressure on the corrugated cardboard web to be processed. This results in the achievement of a considerable improvement in quality. The entire force, either due to dead weight and/or due to additional pressuring via load devices, is distributed evenly across the entire surface onto the pressure element and via the latter onto the corrugated cardboard web.
In an additional embodiment of the invention, the bearing may engage the machine frame on both sides of the corrugated cardboard web in the plane of the upper surface of the conveyor belt at its lower flight. This results in a positive force ratio of the pressure element with respect to the pressured upper surface of the lower half of the conveyor belt. Furthermore, shock elements can be used which take over friction forces from the pressure element. These shock elements are relatively near the friction surface in order to minimize the torque on the pressure element. The entire unit is aligned in such a way, that possible tendencies towards tipping on the part of the pressure elements during an unexpected increase in friction can be prevented.
The pressure elements may be provided with stop screws in order to limit vertical movement.
According to one embodiment of the invention, there exists the possibility of introducing at least one intermediate element and at least one intermediate lever between the bearing and the machine frame.
Alternatively, also in the direction of advance of the corrugated cardboard web, at least one chain may be used whose links are engaged by the individual pressure elements. This chain may be located in a guide of the machine frame and may have an angle element pressured by a lifting element.
The elastic medium which is located between the bearing and the pressure element may be at least a spring or at least a rubber element or an elastic air hose evenly pressuring the freely movable pressure element.
According to one embodiment of the invention, there exists the possibility for the pressure element to surround the bearing. Here, the bearing may be inserted between pairs of springs of the pressure element on the upper and lower side, wherein the bearing is connected with the shock elements pressuring the inside of the pressure element.
In another embodiment of the invention, there is the possibility that the pressure element is C-shaped and is arranged horizontally via at least one elastic medium at the underside of the bearing in a freely movable manner. Between the pressure element and the underside of the bearing, an intermediate plate may be located which supports the above-mentioned shock elements.
In the above-mentioned embodiment, the bearing may be attached, respectively, via intermediate levers at a traverse extending diagonally acro
Hecky Thomas
Knorr Andreas
BHS Corrugated Machinen und Anlangenbau GmbH
Huynh Louis L.
Shaffer & Culbertson LLP
Vo Peter
LandOfFree
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