Printing – Embossing or penetrating – Rolling-contact machines
Reexamination Certificate
1999-09-14
2001-05-15
Eickholt, Eugene (Department: 2854)
Printing
Embossing or penetrating
Rolling-contact machines
C101S025000, C101S225000, C101S228000, C101SDIG029, C242S419300
Reexamination Certificate
active
06230616
ABSTRACT:
The invention relates to a storage device for receiving a loop section of at least one moving, flexible material web, particularly an embossing or stamping film web, between a feed area upstream of the storage device in which the material web is moved with a feed web speed, and a downstream discharge area, in which the at least one material web is moved with a discharge web speed at least periodically differing from the feed web speed.
In the manner of equalizing tanks or material buffers, such storage devices can be used in an apparatus for processing material in the form of at least one flexible material web for separating from one another at least periodically differing material web speeds. The adaptation of the different speeds can take place in that the storage device receives a material web loop section of varying length and in this way compensates speed differences between the feed side and the discharge side, without there being any compression or inadmissible tensile stressing of the material web.
Known storage devices of this type have a vacuum tank into which is sucked a loop section of the material web. At the entry area of the vacuum tank the loop section is held at two points, e.g. on guide pulleys, whilst the intermediate loop section is kept taut by vacuum. The loop section sucked into a more or less deep level acts in the manner of a piston, whilst the associated cylinder is formed by the smooth tank walls. To avoid the drawing in of secondary air, the tank walls facing the web edges must be as close as possible to the border of the material web, so that the width of a vacuum chamber appropriately only slightly exceeds the width of the stored material web. As the suction chamber width must be very accurately adapted to the material web width, on changing from one material web width to another storage devices have to be correspondingly replaced or converted, in that chamber walls are manually moved in order to adapt the chamber width to the width of the new material web. Such vacuum stores are e.g. known from European patent applications 176 905 or 623 432 and have proved satisfactory with relatively stiff or hard material, such as paper or photographic film material. EP 718 099 discloses that such vacuum stores can also be used as film stores for storing stamping film web sections in a rotary stamping machine. With relatively thin, sensitive embossing film material increased constructional and/or control costs may be needed to avoid damage to the film material. With inadequate web tension there can be fluttering of the very light, flabby film material in the air flow of the sucked in air, so that an embossing film web can be damaged and/or the drawing in force of the storage device can be uncontrollably impaired.
The problem of the invention is to provide a storage device obviating the disadvantages of the prior art. The storage device is in particular to permit a problemfree storage of thin, sensitive stamping film material, optionally in several parallel material webs.
To solve this problem the invention proposes a storage device having the features of claim
1
.
In a storage device according to claim
1
of the invention there is on the feed side a first pulling or drawing device for pulling or drawing the at least one material web towards the storage device and on the discharge side a separate, second pulling or drawing device for pulling or drawing the material web towards the storage device. Between the pulling devices to act on one another or opposite to one another with respect to the web running direction and which over a considerable part of the length of the loop section can engage in flat, protective manner thereon, there is a free loop partial section, which is substantially free from tensile forces. It can be very short compared with the total length of the loop section and can remain quiet and flutter-free due to the inherent tension of the material web. The loop partial sections adjacent to the free loop partial section and on which the pulling devices engage in flat manner, can be actively kept spaced apart by the pulling devices. As a result it is in particular possible to avoid the risk of a mutual contact between these loop legs or sides, e.g. due to electrostatic forces. This risk can arise in the case of vacuum stores, in which the total loop section length is unguided or free and corresponding to the loop shape from the interaction between the web tensile forces and by vacuum sucking in forces occur.
A preferred embodiment is characterized in that the first pulling device and/or the second pulling device has at least one preferably sectionwise, planar driving surface movable on a drawing in direction and pressure means for the flat pressing of the material web onto the driving surface. The tensile force of a pulling device can consequently be transferred carefully to the at least one material web over a large or elongated surface area. Through the engagement on the spaced driving surfaces, the corresponding loop legs can be actively and reliably kept apart. Preferably a slip drive is formed between the at least one material web and driving surface accompanied by the building up of sliding friction. The building up of sliding friction whilst avoiding static friction encourages a gentle, jerk-free and material web-protecting conveying thereof and can appropriately be achieved in that the speed of the driving surface in the pulling in direction is higher than the material web speed in this direction predetermined by the conveying means. Preferably the first pulling device and/or second pulling device has at least one circumferential conveyor belt forming the driving surface with in each case one planar section of its outer surface.
In order to produce the necessary pressing of the at least one material web on the driving surface, preferably the pressure means incorporate a suction device for sucking the at least one material web onto the driving surface and which produces a vacuum between the material web and the driving surface.
Alternatively or additionally it is also possible, e.g. by means of a fan and using an air flow, to press the at least one material web from the driving surface-remote side onto the driving surface. Preference is given to such contactless operating pressure means as a result of the material web protection obtained. Such an air flow can in particular be provided by a blower or fan rail, which is located between the two pulling devices and runs transversely to the feed direction of the at least one material web in this area. The at least one material web is passed between the fan fail and the two pulling devices. The air flow passes out of the fan rail in the direction of the two pulling devices, so that the at least one material web is pressed onto the pulling devices. The use of a fan rail is particularly advantageous if several, possibly differently wide material webs are to be intermediately stored in the same storage device. There is no need to provide guide faces engaging closely on the material web in order to maintain the pressure difference between drive face-remote blowout side of the fan rail and drive face-facing side of the pulling devices. This inter alia reduces the changeover times if it is necessary to pass through the storage device new material webs having a different width. In the simplest construction the pulling devices are then constructed as fixed side walls on which the at least one material web engages and along which it slides. The pressure means can also have pressure elements operating by means of contact, e.g. pressure brushes or the like.
For a particularly careful and simultaneously reliable guidance of the at least one material web in the storage device, use is advantageously made of means for adjusting the tensile force for the first pulling device and/or the second pulling device, by means of which e.g. as a function of the average conveying speed in the main conveying direction and/or the material web material the tensile forces can be optimized. A control of the intensity of the
Eickholt Eugene
Nath Gary M.
Nath & Associates PLL
Novick Harold L.
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