DE19921546B4 - Folienlaminator - Google Patents

Abstract

Foil laminator (1) for the thermal lamination of a laminate in the form of a document arranged between two foils or under a foil, with at least two rollers (2, 4) which can be rotated relative to one another, between which a laminating gap (8) is provided for passing the laminate under heating , wherein from a stationary electrical energy source (12) which can be supplied with electrical energy, electrical heating elements (20, 22) are provided for heating at least one of the rollers (2, 4), characterized in that at least one of the heating elements (20, 22) with the Roller (2, 4) for direct heat-conducting heat transfer is also rotatably connected and the transfer of electrical energy from the stationary electrical energy source (12) to the heating element (20, 22) rotating with the roller (2, 4) takes place by induction by Powering a stationary primary coil (16) in a secondary coil (20) rotating with the roller (2, 4) n operating current for the heating element (22) is induced.

Description

State of the art

The invention is based on one Film laminator according to the preamble of patent claim 1.

Foil laminators are used to frequently used documents such as ID cards, menus or operating instructions with a permanent protective cover to be made of plastic film. For this, the document to be protected is in a film bag is inserted, which is open on three sides. The Plastic film of the film bag is multi-layered and consists of usually from an outer PVC layer and an inner polyethylene layer, which on the inside facing the document with a hot glue is provided. After heating through the film laminator, the hot glue penetrates into the pores of the document so that the foil pouch with the Document is inextricably linked. The film pocket protrudes in the Rule about the Edge of the document beyond, making it airtight in the foil pouch is included. In addition to foil pockets, there are also cylindrical spools wound film webs, so-called roll films for use. Laminators are also known which only have paper on one side foil coating Mistake.

Foil laminators are also from the prior art known with a plate heater, in which the laminate for Heating through a laminating gap between two biased against each other Led heating plates becomes. For transport and for additional pressing of the laminate achieve, are in front of and behind the heating plates axially parallel drive roller pairs intended.

Another known version of a Foil laminators do not need plate heating because the drive rollers are heated themselves. Heated traction rollers produce a qualitative better laminate, especially with regard to avoiding blistering, because due to the support of the movement of the laminate, co-rotating roles much higher Contact pressures can be achieved are as between the resting hot plates, in which the hot plate pressure by the high friction between the heating plates and the laminate is limited is. The high contact pressure required for lamination and the required Are warmth therefore advantageously in this construction at the same time and available in the same place.

For the quality of the laminate is over it as far as possible exact maintenance of a certain lamination temperature required - usually Films used are in a narrow temperature range of 103 laminated to 107 degrees Celsius - why usually a temperature control for the Foil laminators is provided. For film laminators with heated Rolls are essentially two methods of roll heating known.

According to a first variant the roles from the outside heated by heating mantles, which hold the rollers at a radial distance almost complete surrounded, with only the area of the laminating gap kept open is. The heat transfer from the heating mantles to the rollers takes place by means of heat flow (convection) or by heat radiation, i.e. through emission and absorption of electromagnetic waves.

On the other hand, roles are in the form of hollow cylindrical roller bodies known, the heating elements with a stationary axis of rotation the rollers connected and with a radial distance to the inner circumference of the rotating reel body are arranged. Because of the one to be bridged Annular gap between the heating elements and the roller body can the heat transfer also only by convection and heat radiation.

In practice, however, that by one exclusively on convection and heat radiation based heat transfer between heating element and roller the problem, the temperature of the rollers keeping within a narrow temperature range is unsatisfactory is solved.

From the DE 27 27 960 B2 A device for welding plastic films is known, comprising a welding element arranged on an axis of rotation, which is inductively heated by means of an induction unit and performs a circular movement relative to the transport direction of the film, the welding element being embodied by a metallic ring attached to a disc made of heat-resistant insulating material , which is assigned to one leg of an iron core excited by means of the coil. Compared to the welding element, which is designed as a narrow disc, the laminating rolls of a film laminator are considerably wider, since it can also be used to laminate documents of larger format, for example. Since the entire film surface is usually welded to the object to be laminated, the laminating roll therefore has at least the same width as this. As already stated, the quality of the laminate requires that a certain lamination temperature be maintained depending on the film used, which is why temperature control is advantageous in heated film laminators. If such a relatively wide laminating roll were to be heated by a direct inductive coupling in accordance with the known document, then on the one hand the heating-up time would be relatively long until a certain target temperature was reached, on the other hand such a system would easily overshoot due to the relatively high mass of the laminating roll tend. Sensitive control of the roll temperature is therefore not possible with the known heating with a direct inductive coupling.

Based on this, it is therefore the Object of the invention to provide a heated film laminator through which a more precise Regulation of the laminating roll temperature is possible.

This object is achieved according to the invention solved, that at least one of the heating elements with the roller for direct heat-conducting heat transfer is rotatably connected and the transmission of electrical Energy from the stationary electrical energy source on the heating element rotating with the roller by induction by energizing a stationary primary coil in an operating current for the heating element of a secondary coil rotating with the roller is induced.

Different from the state of the art the laminating roll is therefore not heated directly, but indirectly, by first only stationary existing electrical energy by means of a primary-secondary coil circuit is transferred to the rotating laminating roll and then with the laminating roll is thermally conductive connected heating elements with the transferred electrical energy are operated. The one with these measures Achievable advantages can be seen in particular in the fact that such Heating elements as actuators can be adjusted much more precisely and quickly than by a large, through eddy currents directly heated laminating roll is the case. It also results from Heating the laminating rolls by means of heating elements is the advantage of one significantly lower hysteresis, the tendency to overshoot decreases.

By the measures listed in the subclaims are advantageous developments and improvements in the claim 1 specified film laminator possible.

See measures that are particularly preferable before that heatable roller is designed as a hollow cylindrical roller body and that by Energizing one regarding the role outer and stationary primary coil in one inside the reel body arranged and with this rotating secondary coil a current for heating of the heating element is induced. The secondary coil is conveniently located in thermally conductive Connection with the inner peripheral surface of the roller body, so that the in it heat generated by the induction process for heating of the roller body contributes. With an appropriate design, the secondary coil can function as the heating elements take over completely.

According to a training include the heating elements ceramic heating plates, each with a ceramic base and a thin one Heating layer made of palladium-containing material, the ceramic heating plates on the inner surface of the roller body are attached. Such ceramic heating plates have compared to conventional ones Resistance heaters a better temperature control as well as a much smaller mass and size on what, among other things Cheap on the moment of inertia and affects the heating speed of the rotating rollers. in principle however, any other can be thermally conductive with the inner surface of the reel body connected heating element can be used.

Another training course provides that the electrical Energy source, which is an AC voltage source, and the primary coil Frequency converter is interposed, which is the AC frequency converts the AC voltage source to preferably 300 Hz to 800 Hz. hereby can the primary and secondary coil and the coil core for a given electrical power very small and turn out easy. Moreover are the required sizes of the inexpensive electrical components.

drawings

An embodiment of the invention is shown in the drawing and in the description below explained in more detail. The only figure shows a side view of a preferred embodiment a film laminator according to the invention in a schematic manner, with an upper roll in longitudinal section is shown.

description of the embodiment

The in 1 according to the preferred embodiment, a film laminator, designated as a whole by 1, comprises two rollers which are driven by drive devices (not shown) 2 . 4 , of which an upper role 4 is shown in section. The central axes 6 of the two roles 2 . 4 are parallel to each other, with the roles 2 . 4 are biased against one another at their circumference in order to generate the necessary contact pressure for lamination. The material to be laminated is then rotated in opposite directions by the rollers indicated by arrows 2 . 4 in a laminating gap shown exaggeratedly in the drawing for reasons of clarity 8th between the roles 2 . 4 moved in.

The roles 2 . 4 are as hollow cylindrical roller bodies 10 trained and each have an AC voltage source 12 fed heating device 14 with a primary coil 16 , a coil core 18 , a secondary coil 20 as well as with heating elements 22 on. The primary coil 16 is from the AC voltage source 12 supplied with alternating current, with an intermediate frequency converter 24 ensures an increase in the output frequency from 50/60 Hz to preferably 300 Hz to 800 Hz.

The coil core 18 is fixed according to the preferred embodiment, with its off the reel body 10 protruding part is the perforated disc-shaped primary coil 16 wearing. The reel body 10 is by means of one between its inner peripheral surface 29 and the outer circumference of the in the reel body 10 protruding part of the coil core 18 pressed roller bearing 26 towards the coil core 18 rotatably mounted, which is why it also has a fixed axis of rotation for the upper roller 4 forms. On that of the primary coil 16 to point the side of the rolling bearing 26 is as close as possible to the primary coil 16 the perforated disc-shaped secondary coil 20 coaxial from the coil core 18 recorded and rotatable relative to this slide bearing. The secondary coil is over its radially outer peripheral surface 20 with the rotating reel body 10 preferably thermally connected and rotates with it. Alternatively, the coil core could 18 also together with the secondary coil 20 and the role 4 relative to the stationary primary coil 16 rotate.

With the secondary coil 20 the heating elements are in the form of ceramic heating plates 22 via electrical lines, not shown, in connection, the ceramic heating plates 22 along the longitudinal and circumferential extent of the inner circumferential surface 29 of the roller body 10 are distributed. The ceramic heating plates 22 consist of a ceramic base body 30 and a thin heating layer 32 Made of palladium-containing material, which is in direct, heat-conducting contact with the inner peripheral surface 29 of the roller body 10 stands.

The function of the heater 14 of the film laminator 1 is as follows: The AC voltage source 12 supplies the stationary primary coil 16 via the frequency converter 24 with an alternating voltage of increased frequency, the periodic changes in current intensity in the primary coil 16 generate a corresponding change in the magnetic flux according to the known transformer principle, which in the with the role 4 rotating secondary coil 20 again induce an alternating voltage. The one in the secondary coil 20 induced AC voltage is used to generate heat in the ceramic heating plates 22 which is directly due to heat conduction on the roll 4 is transferable. In addition, it carries with the roller body 10 secondary coil connected in a heat-conducting manner 20 due to their heating as part of the induction to heat up the roll body 10 and therefore also represents a heating element.

Claims (8)

Foil laminator ( 1 ) for thermal lamination of a laminate in the form of a document arranged between two foils or under a foil, with at least two rollers which can be rotated relative to one another ( 2 . 4 ), between which a lamination gap ( 8th ) is provided for the passage of the laminate under heating, whereby a stationary electrical energy source ( 12 ) electrical heating elements that can be supplied with electrical energy ( 20 . 22 ) for heating at least one of the rollers ( 2 . 4 ) are provided, characterized in that at least one of the heating elements ( 20 . 22 ) with the role ( 2 . 4 ) is rotatably connected for direct heat-conducting heat transfer and the transfer of electrical energy from the stationary electrical energy source ( 12 ) with the role ( 2 . 4 ) rotating heating element ( 20 . 22 ) by induction, by energizing a stationary primary coil ( 16 ) in one with the role ( 2 . 4 ) rotating secondary coil ( 20 ) an operating current for the heating element ( 22 ) is induced. Foil laminator according to claim 1, characterized in that the primary coil ( 16 ) outside of a hollow cylindrical roller body ( 10 ) is arranged, within which the secondary coil ( 20 ) is kept rotating and which is the heated roller ( 2 . 4 ) forms. Foil laminator according to claim 2, characterized in that the outer primary coil ( 16 ) non-rotatable and the inner secondary coil ( 20 ) rotatable on a common cylindrical coil core ( 18 ) are mounted coaxially, which is also a stationary axis of rotation for the roller ( 2 . 4 ) forms. Foil laminator according to claim 3, characterized in that the heating element comprises the inner secondary coil ( 20 ) which, in heat-conducting connection with the inner peripheral surface ( 29 ) of the roller body ( 10 ) stands. Foil laminator according to claim 4, characterized in that the outer primary coil ( 16 ) preferably with a small axial distance to the inner secondary coil ( 20 ) is arranged. Film laminator according to claim 4 or 5, characterized in that the roller ( 2 . 4 ) by at least one roller bearing ( 26 ) on the coil core ( 18 ) is rotatably mounted. Foil laminator according to one of the preceding claims, characterized in that the heating element is ceramic heating plates ( 22 ) includes, each with a ceramic base body ( 30 ) and a thin heating layer ( 32 ) made of palladium-containing material, whereby the ceramic heating plates ( 22 ) on the inner circumferential surface ( 29 ) of the roller body ( 10 ) are attached. Film laminator according to one of the preceding claims, characterized in that the stationary electrical energy source, which is an AC voltage source ( 12 ) and the primary coil ( 16 ) a frequency converter ( 24 ) is interposed, which preferably changes the AC frequency of the AC voltage source to 300 Hz up to 800 Hz.