NL9000870A - SUPPORT OR GUIDE ROLLERS AND APPARATUS EQUIPPED WITH ONE OR MORE OF SUCH ROLLERS. - Google Patents

Description

Short designation: Support or guide roller and device provided with one or more such rollers.

The invention relates to a roller for use in an apparatus for treating a moving web-shaped substrate.

Such rollers are very widely used as support or guide rollers in devices for treating web-shaped media, whereby treatment can be understood to mean a large number of operations such as coating, printing, corona discharge, exposure, etc.

When moving a web-shaped substrate through such a device, it is customary to use rollers for supporting or guiding the substrate, an important requirement being that the roller must not influence the result of the treatment applied to the substrate.

Such rollers can be both driven and non-driven rollers; non-driven rollers are frequently used, whereby the nature of the surface structure causes the roll to be rotated as a result of the substrate moving along it.

Obviously, such a roller must not present a risk of damage to the untreated side of the substrate; nor should such a roller give rise to the accumulation of dust on its surface, as this could adversely affect the course of the substrate. Furthermore, dust accumulation can give rise to unwanted dust swirling with the risk of dust pick-up in e.g. coatings.

Especially at high speeds of the web-shaped substrate, for example speeds of 25 m / min. or higher, with certain roll surfaces, cause problems due to the formation of an air film between the roll surface and the substrate. Such an air film results in slip of the roller, as a result of which the substrate can be influenced in such a way that an applied coating, which should be uniform, will show a stripe-like marking.

The object of the invention is now to provide a roller which is designed in such a way that the occurrence of a disturbing air film between the surface of the roller and the substrate no longer occurs, as a result of which an optimal product as a result of the treatment can be guaranteed and wherein rejection as due to support or guiding roller influences) no longer occurs.

To this end, the roller is characterized according to the invention. in that the surface of the roller coming into contact with the substrate is provided with a surface structure, whereby a predetermined gas volume is enclosed between the substrate which abuts the surface structure i and the roller and the structure is given such a shape that the intended gas volume at the substrate transport speeds used remains essentially the same.

It has been found that by providing a surface structure in the surface of the roll, a situation can be obtained in which the tops of the surface structure of the roll surface remain in contact with the substrate material while an air layer is worn between the substrate and the roll, which cooperates in a supporting manner with the tops of the surface structure whereby a reduction of the contact surface between the substrate material and the roller is obtained and a reduction of the chance of influence of the substrate is realized.

This measure has shown that it is possible to considerably increase the substrate speed without adversely affecting the result of the treatment process.

In particular, the surface structure of the roller is chosen such that a gas displacement within the structure can take place without appreciable pressure increase of the gas.

It has been found that care must be taken to ensure that no air layer can build up in the surface structure which has a considerably higher pressure than ambient pressure.

if this is the case, as discussed earlier, slip can occur between the roller surface and the substrate, whereby the previously discussed adverse effect can again occur.

In severe cases, such effects can even lead to substrate web breakage with all its adverse consequences.

Very efficiently, the surface structure of the roller will be such that this surface structure is mirrored on either side of the center of the roller and gas displacement can take place from the center of the roller to both ends thereof. Air is supplied in the wedge angle between the roller and the substrate moving towards the roller.

By mirroring the surface structure with respect to the center of the roller between its two ends, a suitable design of the surface structure can promote displacement towards the ends, thereby to an even greater extent lift off one of the roll from the substrate. appearance.

Advantageously, the roller according to the invention has a seamless metal sleeve on its surface which comes into contact with the substrate, while the surface structure is arranged on the surface of such a sleeve.

Such a seamless metal sleeve can for instance advantageously consist of a seamless nickel sleeve which is provided with a suitable surface structure. Such a nickel sleeve may, for example, have an outer circumference of about 64 cm and a thickness between 150 and 250 micrometers, although other dimensions and thicknesses can also occur.

In an attractive embodiment, such a sleeve is mounted under axial tension between two shaft mounted end rings. Such a roller has the advantage that its weight can be extremely small, as a result of which the roller will easily rotate with the substrate to be supported or guided.

In the embodiment described above, instead of a closed sleeve, it is also possible to use a sleeve provided with perforations, such as, for example, a metal rotary screen printing stencil. Such a scale can. for example consist of nickel and have a fineness of 250-500 mesh (= holes per linear inch), although lower or higher fineness is possible. The thickness can vary between 100 and 250 micrometers or thicker. When such a perforated sleeve is used, the surface will be. structure may consist of a separately applied structure superimposed on the structure of the sleeve perforation pattern. Also, in certain cases, the structure of the perforation pattern itself will be sufficient to ensure that the web-shaped substrate always remains in contact with the surface of the sleeve.

In an attractive embodiment, means are present within the sleeve, such as e.g. a labyrinth of baffles, to allow the adjustment of an axially extending pressure profile outside the perforated sleeve in a predetermined manner. Such a labyrinth structure may or may not rotate with the perforated sleeve; the pressure profile can be located in the overpressure area and (possibly partly) in the underpressure area. By regulating the pressure within the perforated sleeve, a further perfection of the substrate abutment behavior is possible, whereby even locally occurring imperfections in the substrate abutment can be remedied.

In another attractive embodiment, such a sleeve can be clampingly supported by a support cylinder provided with shaft means.

In connection with the latter embodiment of the roller, reference is made to European Patent 0 160 341 to Stork Sereens; a company that is part of the same group of which the Applicant's company is also part. Said patent describes a method for the production of an anilox roll in which a thin-walled seamless cylindrical screen is slid around the surface of a hollow thick-walled or solid roll.

Before the sieve is placed around the circumference of the support cylinder, the perforations of the sieve are closed, after which the diameter of the sieve is temporarily increased by means of, for example, air pressure, so that it can be slid around the roller.

In the manufacture of the roller according to the present invention, in which the roller is formed by a support cylinder around which a seamless metal sleeve has been clampedly slid, use can also be made of the technique described in the patent.

Another form of a supporting roller is a so-called compressible tensioning roller as described in the non-prepublished Dutch patent application No. 8800781 of Stork Sereens. In said document a support roller is described with a dense, compressible coating on the surface. Sliding a short distance around the liner and pressurized medium, e.g. gas, to be supplied between the sleeve and the liner, the latter is depressed and the entire sleeve is provided to slide the liner. Especially in the case of a sleeve with a large wall thickness, this compressible roller will suffice to form the roller according to the invention.

In order to prevent damage to the substrate as much as possible, it is attractive to round off the parts of the surface structure of the roller that come into contact with the substrate.

The surface structure of the roller according to the invention is very advantageously provided with a top layer with a high wear resistance, such as a nickel phosphorus or chromium layer; the surface structure can also be provided with, for example, a polytetrafluoroethylene coating layer to prevent wear of the roller and damage to the substrate as much as possible.

The invention also relates to an apparatus for treating a moving web-shaped substrate, which comprises one or more substrate treatment units, substrate movement units and one or more substrate support rollers, such an apparatus being characterized in that the substrate support rollers have the shape as described above for a roller according to the invention.

Such a device for treating a moving web-shaped substrate can be, for example, a device for applying a coating to a web-like substrate. As an example, the application of an emulsion to a web-shaped substrate such as a polyester substrate can be mentioned. The uniformity of such a coating is paramount; in the coating device, by supporting the substrate support resp. Carrying out guiding rollers according to the invention, as far as the transport part of the device is concerned, it is ensured that no adverse influence is exerted on the substrate or the coating applied to the substrate. Such a device is expedient, for example, a rotary screen printing device in which a uniform coating is applied to, for example, a polyester web by means of a seamless nickel screen printing stencil. In addition to the aforementioned parts of such a device, it may also contain, for example, drying units in order to be able to subject the applied layer or layers to a drying operation.

The invention will now be described with reference to the drawing, in which: figure 1 to figure 4 show a sketch in partial cross-section and top view of a number of possible forms of a surface structure of the roller; Figure 5 shows a special shape of a part of the surface structure of a roller; Figures 6 and 7 show a special shape of a surface structure which serves to allow gas discharge to the ends of the roller; figures 8 and 9 show surface structures of varying effectiveness; Figures 10 and 11 show a surface structure obtained by electrolytic deposition of metal; and Figure 12 shows the principle of applying a metal seamless cylindrical sleeve around the surface of a support cylinder.

Figures 13 and 14 show the embodiment in which an unsupported sleeve is used.

In Figure 1a, 1 in partial cross-section denotes the body of a roller and a metal seamless sleeve, respectively, while 2 and 3 indicate the surface structure located on the surface of the roller or sleeve. From Figure 1b it is visible in partial top view that the surface structure consists of spheres 2 with spaces 3 while the spheres are arranged in an equilateral triangular structure.

It is noted that the regular structure shown here is not a necessity; the surface of a roller or sleeve can also be given a roughness character by, for example, sanding, sandblasting, pearl blasting or shot peening, whereby the roughness will expediently have a value Ra of up to 12.5 micrometers. A normal smooth roller or a metal sleeve obtained by galvanic precipitation, such as a nickel sleeve, will have a roughness Ra ≤ 0.2 micrometer.

In figure 2a it is indicated that in the roller or sleeve body 4 cavities 5 are formed by etching. Depending on the application, the width and depth as well as the pattern configuration of the grooves 5 can be chosen.

In figure 3 it is indicated that the roller or sleeve body 7 is provided with a structure of randomly placed balls 6, such balls being connected to the surface of the roll or sleeve by adhesion. It is noted that in such an embodiment, following the formation of the surface texture layer, a further calibration operation must be performed in order to provide the roller with circulation accuracy; the calibration operation also serves to ensure that all spherical parts have the same height above the surface of the roller or sleeve. In figure 3b the situation from figure 3a is shown in top view as was also the case in figure 2b with regard to figure 2a.

In Figure 4a, 9 denotes a groove in the surface of a roller or sleeve, the elevations between the grooves being indicated by 8. It can be seen from Figure 4b that the grooves are spiraled in the longitudinal direction of the roller, assuming that the axis direction of the roller is in the direction of the arrow indicated in Figure 4b. Incidentally, it is noted that in all the figures given above, an axis direction of the roller or sleeve is assumed to be equal to the direction of the pipe in Figure 4b. In figure 4c it is indicated that the tops of the material 8 between the grooves 9 are rounded by additional processing steps such as gloss pickling, lapping, etching and the like.

In figure 5 it is indicated that a surface structure can be obtained by working the surface of the roller and a sleeve to be used with a knurled wheel, whereby recesses 10 are connected which are connected by means of channels 10 'so that a gas displacement possibility is nevertheless possible. between the floors are guaranteed. In addition to the aforementioned mechanical formation of the floors, the formation of floors by means of electron beam engraving or laser beam engraving in metal can of course also be envisaged.

Figures 6 and 7 indicate two very attractive embodiments of a surface structure of a roller or sleeve, wherein the structures are mirror-mirrored relative to each other around the center of a roller. In figure 6 a groove pattern 13 is shown in part 11 on the right-hand side of the center, the pattern 13 being arranged in such a spiral that in case of rotation of a roller in the correct direction a gas transport takes place in the drawing to the right. On the left side of the center of the roller in part 12, the groove pattern is opposite, so that with the same rotation a gas transport to the left can occur.

Figure 7 shows the same situation where a pattern of overlapping opposite pitch is present in either part on either side of the center of the roller. In such a situation, a groove width gradient can be applied, whereby, for example, the resistance to displacement, m, the grooves from left to right decreases for one of the pitches and from right to left for the other pitch.

Such mirror-like embodiments appear to be very advantageous if, in addition to this, a controlled pressure build-up of the gas must also involve effects which must promote the positional accuracy of the substrate during its movement. By symmetrical air displacement from the center of the roller, an improved positional accuracy of the substrate relative to the roller is obtained, while also a certain flattening side effect on the substrate web is observed, which is extremely desirable with specific materials and small film thicknesses. Etching techniques using photoresist patterns can advantageously be used to form such patterns, while groove depth variation can also be realized using special techniques. In this case, of course, the aforementioned beam processing techniques can also be used to form the groove patterns, using electrons and laser beams, respectively.

Figure 8 shows a surface structure of a roller 19 with circumferential grooves 20 present. In this case, no air displacement takes place to the end of the roller; nevertheless, by suitable dimensioning of the grooves, a continuous contact of the substrate against the material between the grooves 20 can be ensured.

Figure 9 shows a situation in which the surface 21 is provided with axially extending grooves 22.

In practice, this situation appears to be less satisfactory and, with certain groove dimensions, can lead to vibration of the substrate web.

Figures 10 and 11 indicate that a surface structure on a roller or sleeve can also be obtained using galvanic techniques. In Figure 10, a roller or sleeve body 23 is indicated, while 25 indicates a galvanic metal deposit grown between photoresist areas previously located at the locations now designated 24.

In Fig. 11, on a roll or sleeve name 26, a galvanic deposit 27 has been formed with an overgrowth 28, the overgrowth having occurred over photoresists located at the locations indicated by 29.

By selecting the growth / overgrowth ratio suitable for controlling the airflow along the surface of the roller or sleeve can be worn zora.

Figure 12 shows schematically how a sleeve 30 can be applied around the surface of a roller 32 in a manner as indicated in the aforementioned European Patent 0 160 341.

The roller in this case is a thick-walled hollow roller which is provided with support shafts 35 and 36 which have disc-shaped parts 37 which are clamped in the ends of the cylinder. The disc-shaped parts 37 rest against a collar on the inside of the cylinder. One of the ends of the cylinder 32 is provided with a number of radial openings 38 opening to the outer periphery of the cylinder and communicating with axially oriented channels 40 arranged in the left disc-shaped portion 37. Each of the channels 40 has a blind end or a sealing cap 39? the other end of the channels 40 communicates with the interior space 33 of the carrier cylinder 32. The. disc-shaped portion 37 on the right-hand side of the cylinder has at least one axially oriented channel 34 which on the one hand communicates with the space 33 and on the other hand with a connecting nipple 41. The nipple 41 can be connected via a hose (not shown) to a source of neither shown the medium, usually compressed air.

In order to mount the cylinder 30 on the roller 32, the outer part of the cylinder 32 is chamfered so that the sleeve 30 can be slid along the chamfered part over the openings 38. Subsequently, a pressure medium is supplied into space 33 via connection 41 and channel 34, such that sleeve 30 is expanded slightly and can thereby slide further over carrier cylinder 32. The pressure medium thereby has the double function of expanding sleeve 30 and at the same time act as a lubricant when sliding the sleeve over the carrier cylinder.

After completion of the slip-on operation, a connection to the source of pressure medium can be broken and this medium leaks out, after which the sleeve 30 is clamped on the carrier cylinder 32. In Figure 12, the surface of the carrier cylinder 32 is indicated by a dotted line that the cylinder is chromed on the outside or covered with a thin chromed cuff which serves to provide the surface of such a cylinder with sufficient wear resistance so that it can be used many times. turn into.

With regard to the rollers and sleeves to be used according to the invention, it can be noted that in general a high degree of wear resistance will be sought, which can be achieved on the one hand by using a wear-resistant material with a low friction coefficient such as polytetrafluoroethylene; on the other hand, a wear-resistant material with a high hardness can also be used.

Ion implantation techniques 5CVD (Chemical vapor deposition) and PVD (Physical vapor deposition) can also be used to provide wear resistance properties on the surface of a roll or sleeve.

The materials to be applied with the above techniques can be many.

The following can be mentioned: - Nitrides such as titanium and boron.

- Carbides such as of silicon, boron, tungsten and titanium.

- Quartz and glass.

Such high hardness layers can furthermore be, for example, galvanically or electrolessly deposited layers, such as, for example, a chrome layer or a nickel-phosphor layer. As for the hardness, for example, a hardness greater than 500 ° Vickers will give good results.

Figure 13 shows the situation in which a roller according to the invention comprises a sleeve 52 accommodated between end rings, which may or may not be perforated and which may or may not have an additional surface structure.

The end rings in this case are schabloone end rings 50 such as these e.g. are used in rotary screen printing machines. The ends 53, 54 of the rings are configured to fit into the goblet heads of a device in e.g. a bayonet catch can be included. The rings can exert an axial tension on the sleeve 52 in a machine; however, this is not necessary. End rings 30 and 51 may also be replaced by end rings mounted on a common shaft; axial tension can be obtained if necessary by sliding the rings on the shaft apart.

Figure 14 shows the situation that the sleeve 52 is a perforated sleeve, such as a rotary screen printing stencil. The shaft 56 here carries a labyrinth 57 for realizing a predetermined pressure profile along the length of the sleeve. By varying the labyrinth bulkhead distances and suitable placement of gas inlet and / or outlet openings, a suitable underpressure and / or overpressure locations including axial profile can be set.

Claims (8)

Roller for use in an apparatus for treating a moving web-shaped substrate, characterized in that the surface of the roller coming into contact with the substrate is provided with a surface structure (3, 5, 6, 9....), Which a predetermined gas volume is enclosed between the substrate abutting the surface structure (3, 5, 6, 9 ...) and the roller and the structure is shaped such that the gas volume remains substantially the same at the substrate transport speeds used. Wal according to claim 1, characterized in that the surface structure (3, 5, 6, 9 ...) is such that a gas displacement within the structure can take place without appreciable increase in pressure of the gas. Roller according to claim 2, characterized in that the surface structure (11, 12; 15, 16) is mirrored on either side of the center of the roller and gas displacement can take place from the center of the roller to both ends thereof. Roller according to one or more of claims 1-3, characterized in that the roller on its surface which comes into contact with the substrate comprises a seamless metal sleeve (30) and the surface structure is arranged on the surface of the sleeve (30) ). Roller according to claim 4, characterized in that the sleeve (30) is mounted under axial tension between two attached end rings. Roller according to claims 4-5, characterized in that the sleeve is a sleeve provided with perforations. Roller according to claims 4-6, characterized in that means are provided within the sleeve for setting a printing pattern predetermined in axial direction. Roller according to claim 4, characterized in that the sleeve (30) is carried clampingly by a support cylinder (32) provided with shaft means (35, 36, 37). Roller according to one or more of the preceding claims, characterized in that the parts of the surface structure that come into contact with the substrate are rounded (8), roller according to one or more of the preceding claims, characterized in that the surface structure is provided with a top layer of great wear resistance. Roller according to claim 10, characterized in that the top layer comprises a wear-resistant material selected from: - Nitrides such as of titanium and boron. - Carbides such as of silicon, boron, tungsten and titanium. - Glass and quartz. Roller according to claim 10, characterized in that the surface structure is provided with a metal layer of high wear resistance and hardness, such as a nickel-phosphor layer or a chrome layer. Roller according to claim 10, characterized in that the surface structure is provided with a polytetrafluoroethylene coating layer. Device for treating a moving web-shaped substrate and comprising one or more substrate treatment units, substrate moving means and one or more substrate support rollers, characterized in that the substrate support rollers have the shape as described in one or more of claims 1-13.