Adhesive bonding and miscellaneous chemical manufacture – Surface bonding means and/or assembly means therefor – Presses or press platen structures – per se
Reexamination Certificate
2000-11-01
2003-09-30
Sells, James (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Surface bonding means and/or assembly means therefor
Presses or press platen structures, per se
C269S021000, C269S266000
Reexamination Certificate
active
06626225
ABSTRACT:
TECHNICAL FIELD AND BACKGROUND OF THE INVENTION
This invention concerns a press table insert for a coating press.
For coating form boards, in particular form boards with milled cuts used as front panels in furniture construction, with film on the surface as well as on the edges in a single pass process, press machines are used in which the workpiece is placed on a support whose circumference is slightly retracted with respect to the edge of the workpiece. This makes it possible for the film to nestle not only on the surface into the milled cuts, but also allows it, after applying increased or decreased pressure, to pull down at the edges and finish flush therewith.
Press machines are known for which the supporting body must be specially made for the particular workpiece. This is certainly a satisfactory solution for mass production with workpieces which have constant dimensions. But if the dimensions of the workpiece vary frequently, in particular for special production, very many different supports must be quickly available in this case. This entails enormous work effort and costs.
Press machines are also known which use modular components to produce the required supports.
For example, the document DE 295 00 248 describes a modular components system for plate/board workpieces in which support plugs are inserted into holes according to a given pattern for supporting the workpiece. However, the pattern must be determined and implemented separately for each kind of workpiece, and it can carry only one particular workpiece, like the solid supports. The support must be created new if it is necessary to quickly coat another different workpiece together with the main workpiece in each pressing cycle.
Thereby it makes no difference whether the second workpiece is smaller or larger than the first one, because the same support cannot be used for both workpieces in either case. If the second workpiece is too large, it cannot be supported securely, so that there is a danger that it will break when the applied pressure per unit area is too large. If the second workpiece is too small, the already set plugs prevent proper coating of the edges, because the film cannot be completely pulled down.
The document PCF/DE97/00544 shows a coating press in which the laying table has a table plate with raster breakouts in which movable carriers are inserted. These carriers can be moved out of the table plate to lift the workpiece off the table plate. Furthermore, sensors are provided which determine the size and position of the workpiece. The carriers are actuated via deflecting rockers to generate the support pattern. However, the workpiece is sensed row by row of the carriers before it can be moved up. This is a time-consuming process tending to slow-down production.
This device also requires a complicated expensive control mechanism, and the variability of the workpieces is still restricted by the rather large supporting plates resting on the carriers.
SUMMARY OF THE INVENTION
The purpose of this invention is to produce a press for film coating form boards on several sides, avoiding the disadvantages of the known solutions while providing supports for any workpiece quickly and cheaply.
This invention is also intended to provide a solution which can be retrofitted to machines which are workpiece movable through a certain horizontal range of displacement of the press table, and by reducing the height of each individual carrier during the pressing process.
The range of movement assigned to each individual carrier permits an arrangement of the carriers such that workpieces of any shape and size can be coated without first having to define a supporting pattern. It suffices to place the workpieces onto the carriers and then to adjust the positions of individual carriers on the outer edges of the workpieces. This can be done quickly and efficiently because it is not necessary to maintain any exact clearance dimension. The height of each individual carrier is also shortened during the pressing process to assist the latter. This is of advantage in particular because an initially higher carrier brings the workpiece closer to the heating device, so that the radiant heat pre-heats the parts which are to be film-coated, thus ensuring better edge and surface adhesion strength, because the film does not have to be heated as much since the workpiece is already hot. Furthermore, the film coating in the vacuum drawing work step is carried out without any problems while the workpieces are high. When pressure is applied in the next step, the lower height is more advantageous for preventing film problems in the corner regions, in particular wrinkles or tearing of the material. Therefore reduction of the height of the individual carriers during the pressing process is major step towards work process simplification.
In principle, every range of movement around every individual carrier can be made arbitrarily large. This solution can prove to be favorable in particular for making special workpieces as well as for special tasks. Some examples are glass frame pressing, frame pressing in general, film coating of round and polygonal pieces.
For producing standard parts as well as simple rectangular workpieces such as furniture fronts, it is of advantage to make the range of movement equal for all individual carriers. The mutual separations of adjacent ranges of movement can also be made equal. This defines a symmetrical pattern with uniform minimum and maximum mutual separation of the individual carriers. At any rate, it is necessary not to undershoot a minimum separation of adjacent ranges of movement, and this also defines a minimum separation of adjacent individual carriers. Such an arrangement soon leads to problems for coating the workpiece surfaces. This can be combated by providing a minimum separation.
This invention envisages that each individual carrier has the same length and consists of a shaft, a base and a covering layer resting on the base. The shaft and base are preferably made of rigid material, for example plastics such as polyamide or cellamide, or of aluminum, whereas the covering layer consists of elastic material to make possible shortening of the height of the individual carriers during the pressing process. The covering layer also avoids direct contact between the workpiece underside and the rigid material of the base which would not be optimum for taking up the high working pressures and could also damage the workpiece underside. Therefore a covering layer of elastic material is provided on the upper side of the base. After relaxing the working pressure again, this material returns to its original form each time and is therefore suitable for withstanding very many such elastic compression cycles under high pressure as well as high temperature. By virtue of providing this covering layer, it is now also possible to position the workpiece from below in an appropriate height when operating with vacuum drawing, in order to achieve film coating in the corner regions too without wrinkles. Film coating thereby takes place while the vacuum is building-up. The covering layer reaches its minimum height, in which state its compression is maximum, at the same time as the vacuum reaches its lowest pressure. When pressure is applied thereafter to continue the process, the distance between the workpiece and the supporting plate has become so small that even high pressure will no longer lead to bursting or tearing of the film.
Conventional devices always have to work with a minimum value in relation to the known film properties and thus operate with much greater danger of producing rejects either as film injury or improper film coating.
The covering layer is provided with a gripping surface to prevent slipping of the workpiece.
In a good design the shaft widens from the covering layer to the base and advantageously takes the form of a pyramidal or conical frustrum. This design ensures unproblematic separation of the film from the individual carriers after the pressing process.
According to a further design variant the
Adams Evans P.A.
Renate Kochberger
Sells James
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