EP1377411B1 - Support bodies and method for improving wear and tear on support bodies in large-scale grinders - Google Patents

Abstract

The invention relates to a method for improving wear and tear on support bodies (54) for plates or grinding belts in large-scale grinders (1). The support body (54) has a base body (18), onto which an abrasion-resistant primary layer of at least 0.3 mm thickness is applied using a thermal spraying process. This is configured as an inhomogeneous layer with an oxide entrapment of a specific porosity. If the support body (54) is a roll for the forward feed unit (20, 28), the roll body is roughened and a primer and the primary layer are applied using a thermal spraying process. Approximately 50 % of the primary layer consists of chromium steel, in particular 13 % chromium steel and an abrasion-resistant hard material and said primary layer provides a coarse surface with good grip that is resistant to wear and tear. If the support body (54) is a grinding-belt contact roll (9, 9'), the latter is polished after the thermal spraying process. If the support body (54) is a grinding belt shoe (50), the base body (18) is roughened and an adhesive layer and then the primary layer are applied in a thermal spraying process. The wear-resistant primary layer is polished to create a smooth surface and the layer construction is configured to produce a high degree of slip.

Description

Technical area

The invention relates to a method for improving the Verschleissssituation of supporting bodies in wide grinding, in particular at least for the driven rollers of the feed unit and / or the Schleifbandkontaktwalzen and / or the back pressure shoe and / or the counter-pressure roller according to the preamble of claim 1. The invention further relates to support body for Plates or abrasive belts in wide grinding machines, which are designed either as driven rollers of the feed unit and / or as a grinding belt contact rollers and / or as counter-pressure shoes and / or the counter-pressure roller according to the preamble of claim 8. Such a method, or such a device are from the document DE-U-8814128 known.

State of the art

Wide grinding machines have been established for several decades to a separate class of grinding machines. They are grinding machines of considerable size. The height is 1.5 to 3 meters, and the length may vary from one meter to many meters, depending on the sanding heads. In particular, the width of the machine, which can range from 1 to over 3 meters, is typical. As a rule, a wide grinding machine is adapted to the specific conditions, especially the width of the workpieces to be ground. Workpiece by workpiece is continuously fed through the machine. In technical terms, therefore, larger systems are referred to as a grinding line, which includes incoming and outgoing transport. A typical application is the grinding of raw chipboard. The majority of the lower and upper surfaces are ground simultaneously over the entire width. Raw chipboard has an over-thickness of 0.5 mm or more immediately after pressing and, after the grinding process, should be brought to a nominal size with a thickness tolerance of ± 1 ÷ 3/100 mm. The thickness tolerance must be maintained uniformly over the entire surface. The finished workpiece requires a very high surface quality. The calibration grinding as the first grinding stage requires powerful motors for the removal of the quite large amount of material. The same applies to the forced delivery of slabs to be ground. Again, quite large shear forces occur. The correspondingly enormous grinding work also requires the highest accuracy and stability of the machine, in particular of the machine stand, with plate sizes of several m ² . Wide sanding machines use a wide variety of abrasives. This is already apparent from the nature of the grinding intervention, be it calibrating, fine or shoe grinding. For this purpose, sanding belts, sanding rollers or brush rollers are used in the first place. In addition to the mentioned plate grinding the generic wide grinding machine is used in many other areas, eg for carpentry, doors, in addition to hard and soft fiber boards and plywood or other laminates for gypsum fiber boards, cement fiber boards, floor coverings, also for rubber flooring, parquet, cork and straw boards, especially for metal grinding. In accordance with the sometimes very intensive grinding work, the abrasive belts and grinding rollers but also brush rollers in the classic sense wear parts that have to be replaced or reworked after a relatively short labor input. It is a virtually unalterable wear of the working means, which are indeed tougher and harder than the workpiece to be machined, but wear off.

• ∘ Die Walzen für die Vorschubeinheit haben die Aufgabe der präzisen Führung der Werkstücke durch die Breitschleifmaschine sowie, im Falle der angetriebenen Walze, den Werkstücken die notwendige Schubkraft zu erteilen. Die Durchlaufgeschwindigkeit soll unabhängig der jeweils momentan notwendigen Schleifarbeit möglichst konstant sein. Die angetriebenen Walzen für die Vorschubeinheit haben eine profilierte Oberfläche. Am häufigsten wird für die Erzeugung der Oberflächenprofilierung das sogenannte Kordeln eingesetzt. Dabei werden durch kreuzweise, diagonal eingefräste Rillen von etwa 2 - 3 mm Tiefe die vorstehenden Noppen gebildet. Die Noppen geben gegenüber dem zu bewegenden Werkstück einen guten Griff, so dass die notwendigen Kräfte übertragen werden können. Der Schlupf zwischen den Noppen der Walzen und dem Werkstück ergibt einen Abrieb an der Walzenoberfläche. Um die Griffigkeit zu erhalten, müsste die Walze von Zeit zu Zeit erneut durch Kordeln in den ursprünglichen Zustand gebracht werden. Weil dabei etwa 1 - 3 mm abgetragen werden müssten, ergäbe sich nach dem Nachkordeln eine Walze von kleinerem Durchmesser, so dass die bearbeitete Walze nicht mehr in einer Reihe mit anderen Walzen eingebaut werden könnte. Im konkreten Einsatz könnten die nachbearbeiteten Walzen nicht mehr wiederverwendet werden.
• ∘ Andere Bedingungen liegen bei der Schleifbandkontaktwalze vor. Das Schleifband wird über eine Schleifbandkontaktwalze angetrieben. Auch hier ist wegen der enormen Kräfte, die übertragen werden müssen, ein gewisser Schlupf unvermeidlich. Die Situation ist in zweifacher Hinsicht schwieriger im Verhältnis zu der angetriebenen Walze der Vorschubeinheit. Die mit Noppen versehene Vorschubwalze greift das rohe, ungeschliffene Werkstück an, so dass Eindrücke im Werkstück in einem gewissen Ausmass zulässig sind. Die Schleifbandkontaktwalze muss glatt sein, damit über das Schleifband die hohen Anforderungen für den Oberflächenschliff an dem Werkstück erzielbar sind. Um die Antriebskräfte überhaupt auf das Schleifband übertragen zu können, wurde versucht, die Oberfläche zu vergüten, so dass trotz glatter Walze sich eine verbesserte Adhäsion und Abriebfestigkeit ergibt. Die Anmelderin selbst versuchte, mit grösseren Anstrengungen über das Plasmaspritzverfahren die genannte Oberflächenvergütung zu erreichen. Es sind beim Plasmaspritzen zwei Verfahren bekannt: Beim atmosphärischen Plasmaspritzen wird zwischen einer anodisch gepolten, wassergekühlten Düse und einer Wolframkathode ein Lichtbogen gezündet. Dieser wird von den Plasmagasen (im Allgemeinen Ar mit Zusatz von H2 oder He) durchströmt, wodurch sich ein hochenergetischer Plasmastrahl ausbildet. Der pulverförmige Spritzzusatz wird mit Hilfe spezieller Pulverförderer zugeführt, im Plasmastrahl aufgeschmolzen, auf den Grundwerkstoff hin beschleunigt und zu der gewünschten Schicht aufgetragen.

A second category is the carrier or support body, be it for the abrasive belts or the workpieces to be machined, such as chipboard. These are support bodies which move themselves, or have their own drive or stand still and serve to press the grinding belt past it onto the workpiece to be machined.

• ∘ The rollers for the feed unit have the task of precisely guiding the workpieces through the wide grinding machine and, in the case of the driven roller, to give the workpieces the necessary thrust. The throughput speed should be as constant as possible regardless of the currently required grinding work. The driven rollers for the feed unit have a profiled surface. Most often, so-called cording is used for the generation of surface profiling. Here are formed by crosswise, diagonally milled grooves of about 2 - 3 mm depth, the protruding knobs. The knobs give a good grip against the workpiece to be moved, so that the necessary forces can be transmitted. The slippage between the nubs of the rolls and the workpiece results in abrasion on the roll surface. To maintain the grip, the roller would have to be restored to its original condition from time to time by cording. Because about 1 - 3 mm would have to be removed, would result after Nachcordeln a roll of smaller Diameter, so that the machined roller could not be installed in a row with other rollers. In concrete use, the reworked rolls could not be reused.
• ∘ Other conditions exist with the grinding belt contact roller. The sanding belt is driven by a sanding belt contact roller. Again, because of the enormous forces that must be transmitted, a certain amount of slippage is inevitable. The situation is two times more difficult in relation to the driven roller of the feed unit. The nubbed feed roller engages the rough, unpolished workpiece so that impressions in the workpiece are permitted to some extent. The sanding belt contact roller must be smooth so that the high demands for surface grinding on the workpiece can be achieved via the sanding belt. In order to be able to transfer the driving forces to the grinding belt at all, an attempt was made to re-treat the surface so that, despite a smooth roller, improved adhesion and abrasion resistance results. The applicant itself attempted to achieve the surface coating mentioned with greater efforts via the plasma spraying process. Two methods are known in plasma spraying: In atmospheric plasma spraying, an arc is ignited between an anodically poled, water-cooled nozzle and a tungsten cathode. This is traversed by the plasma gases (generally Ar with the addition of H2 or He), which forms a high-energy plasma jet. The powdered spray additive is supplied by means of special powder conveyor, melted in the plasma jet, accelerated towards the base material and applied to the desired layer.

• Vorwärmen des Werkstücks, Reinigen der zu beschichtenden Oberfläche, Zuführen zusätzlicher Energie zum Aufschmelzen der Teilchen und Konstanthalten der Substrattemperatur während des Spritzprozesses zur Optimierung der Schichtgefüge. Mit dieser Technik lassen sich speziell Werkstoffe mit hoher Sauerstoffaffinität (wie Ti, Tic oder Ta) oxydfrei verspritzen.

The second method is vacuum plasma spraying. An essential part of a vacuum plasma spraying system is the approximately 2 to 3 m ³ large vacuum chamber, which is evacuated before the start of the process. Due to the high particle velocity and the good melting conditions, a layer porosity of less than 1% can be achieved. In this method, an additional transferred arc between the anode of the burner and the workpiece can be ignited. The following functions are assigned to this transferred arc:

• Preheating the workpiece, cleaning the surface to be coated, supplying additional energy to melt the particles and keeping constant the substrate temperature during the injection process to optimize the layer structure. With this technique, especially materials with high oxygen affinity (such as Ti, Tic or Ta) can be sprayed free of oxides.

A number of abrasive belt contact dies were treated by the vacuum plasma spray process. However, apart from a few very specific cases, the plasma spraying method has not been successful in practice. Despite the hugely expensive plasma deposition technique, damage to the surface of the roll occurred locally in some cases after a certain period of operation, thus negating the improved surface.

The third support body, which is known for an almost extremely strong wear situation, is the abrasive belt shoe and the back pressure shoe. The back pressure shoe requires high lubricity directly to the plate material. In the prior art, a plate-shaped intermediate layer, which is enriched with graphite, is arranged between the abrasive belt shoe and the abrasive belt. The abrasive belt shoe, the graphite layer can be replaced after wear. Apart from the mentioned graphite intermediate layer, the support bodies described are not classic wearing parts, since the wear is relatively low. Nevertheless, from time to time either a complete replacement of the back pressure shoe and in the case of the grinding belt contact roller a relatively complex regrinding is necessary. After repeated regrinding such a reduction of the diameter of the grinding belt contact roller is achieved that a new roller must be used here as well. Wide belt sanders have to be overhauled in a larger cycle and defective parts, such as bearings, drives, etc., replaced. It is disadvantageous if the individual components have different service lives, so that the corresponding service work between two large overtaking cycles can cause an undesired standstill of the machine.

US-A-5644828 describes the repair of low loaded printing rollers in printing machines by applying a Verschleissschuhschicht on the roll body by thermal spraying. When applying a thin coating, polishing is required, and when applying a thick coating, sanding followed by polishing.

The invention has now the object of developing a method and a device to the Verschleisssituation in terms of value maintenance and on the To improve service life of the support body and to optimize the maintenance situation of the whole machine.

Presentation of the invention

The object is achieved with the features of claim 1 and with the features of claim 8.

With the invention it has been recognized that in the previous proposed solution with the spraying of a plasma layer several parameters were ignored. An important finding is that a sufficient layer thickness is very important. Since a relatively soft base body is usually selected under the thin layer of 0.1 to 0.2 mm, surface damage can easily occur. It may also occur a runaway. The plasma spraying process has the fundamental advantage for certain applications that a relatively homogeneous layer with a very low porosity is produced. According to the new invention, however, it has proven to be a great advantage if a much thicker inhomogeneous layer of more than 0.3 mm is produced. It is particularly advantageous if the entire layer has as many oxide particles of different sizes. Even with constant wear of the surface, the texture of the surface remains unchanged, as continuously new pores and oxide particles within the layer thickness come to fruition. Due to the porosity, regardless of the wear, a good grip is maintained. If the main layer has a sufficient thickness, even repeated sanding does not change the surface structure. Apart from very special applications, the plasma spraying process does not bring the mentioned advantages. The plasma spraying process is also much more cumbersome and expensive.

The previous experiments have shown surprisingly good results, in particular in the case of the driven roller of the feed unit. It is known, especially with highly stressed, rotating rollers, that premature damage and break-outs can occur in the case of layers with different materials as a result of the stress, which is usually not completely transparent. However, concerns about the new solution have not been confirmed after a lengthy trial run. On the other hand, it has been shown that the inventive thermal application process results in particular advantages in each of the support bodies described. The thermal application process is relatively easy to use once all critical parameters for the job are known. The order procedure can, if necessary, even by Production plant itself, in contrast to plasma spraying or casting, which always require a highly specialized facility.

After a certain wear of the surface of a support body can be restored by re-thermal application of the new state and thus the original dimensional accuracy with relatively little effort. The thermal application can be done within a few tenths of a millimeter, depending on the specific requirements. After working up by the thermal arc spraying process, the support body is basically new again. The invention allows a number of particularly advantageous embodiments, for which reference is made to claims 2 to 8 and 10 to 13. The surface is roughened to improve the adhesion, as known per se, prior to the thermal application by means of sandblasting.

It also opens up completely new possibilities in that the body no longer, as hitherto, must be a metal body. The main body can be made entirely or partially of plastic, wherein in each case a specially adapted adhesive layer is applied before the application of the main layer, likewise by thermal arc spraying. It can be influenced by non-metals directly in a positive sense to the vibration or vibration behavior in order to avoid a surface oxidation.

In the arc spraying process, the electrically conductive spray additives are processed in wire form. If the base body is an oxidizable metal body, the thermal layer application should be carried out within a limited time, in particular less than three hours after the surface roughening.

The thermal spraying process has the enormous advantage that an almost arbitrary layer thickness can be produced by the transfer of the metal particles. A partial oxidation of the oxide-forming elements or metals takes place, accompanied by an air flow. The order is on the outer surface after its completion very rough and has, especially on the surface, oxide particles of different sizes. These result primarily in the wear-resistant and hard surface texture. If the hard main layer is slowly removed by the abrasion, then new oxide particles are effective on the surface in-line, so that, regardless of the abrasion, a rough, non-slip and wear-resistant surface finish remains virtually unchanged.

The cording in the case of the rollers for the feed unit according to the prior art is relatively cumbersome and requires a relatively long manufacturing process. The wear is relatively high even with good quality (e.g., ST 52), and thus the prior art rolls are not wear resistant. On the other hand, the arc spraying method is fast, easy and provides a wear quality that is much higher than that of a structural steel. The hardening of structural steel would especially complicate a subsequent reworking extremely. After its roughening, an adhesive layer, in particular of aluminum bronze or zinc substrate, prior to the application of the main layer by the arc spraying method, is most preferably applied thermally. The primer may have a thickness of about 0.1 to 0.3 mm. The main layer is applied at a thickness of about 0.4 - 5 mm, preferably 0.5 to 2 mm, wherein the layer thickness in the case of the abrasive belt roller and / or the abrasive belt shoe after surface grinding at least 0.2 - 1 mm. Because primer and main coat can be applied by the same method, the work involved is greatly simplified. In the case of rolls for the feed unit of the roll body, these are roughened in advance, and thereafter, a primer and the main layer is applied by the arc spraying process thermally. The main layer consists in the roller for the feed unit each about half of chrome steel, in particular 13% chromium steel, and abrasion resistant hard material, wherein on the main layer a rough, non-slip and wear-resistant surface is produced.

In the case of abrasive belt contact rollers, the base body is roughened and thermally a) a primer and then b) applied the main layer by arc spraying. The main layer is preferably made of about 13% chromium steel. The surface is ground after the thermal deposition of the main layer to produce a smooth surface. In the case of back pressure shoes, a sliding plate is fastened on a solid support body, which is provided with a wear-resistant layer structure according to the invention.

Brief description of the invention

die Figur 1

eine Breitschleifmaschine für doppelseitigen Schliff mit zwei Grobsowie zwei Feinschleifstufen mit Schleifbändern;

die Figur 2

eine Breitschleifanordnung mit zwei Kalibrierstufen und zwei Feinschleifstufen, wobei die Feinschleifstufen Schleifwalzen oder Schleifbürsten aufweisen;

die Figur 3

eine Ansicht gemäss Pfeil III in der Figur 1, schematisch der Antrieb der Schleifbandkontaktwalzen;

die Figur 4

einen Gegendruckschuh gemäss neuer Lösung;

die Figur 5

schematisch einen vollständigen Aufbau der Breitschleifmaschine mit Maschinen- und Prozesssteuerung;

die Figur 6

diagrammatisch die verschiedenen Verfahrensstufen für die Behandlung der Schleifwalze nach der neuen Lösung;

die Figur 7

übereinander drei verschiedene Schnittbilder von thermisch in Spritzverfahren aufgetragenen Schichten;

die Figur 8

drei Schnittbilder mit geschliffener und ungeschliffener Hauptschicht sowie der Verhältnisse der jeweiligen Materialhärte.

The invention will now be explained with reference to some embodiments with further details. In the examples, in each case the support body which has a wear-resistant layer structure according to the invention is marked in black. Show it:

the figure 1

a double-sided grinding machine with two coarse grinding wheels and two grinding stages with grinding belts;

the figure 2

a wide grinding assembly having two calibration stages and two fine grinding stages, the fine grinding stages comprising abrasive rollers or brushes;

the figure 3

a view according to arrow III in Figure 1, schematically the drive of the grinding belt contact rollers;

FIG. 4

a back pressure shoe according to the new solution;

the figure 5

schematically a complete construction of the wide grinding machine with machine and process control;

the figure 6

diagrammatically the different process steps for the treatment of the grinding roller according to the new solution;

the figure 7

on top of each other three different sectional views of layers applied by thermal spraying;

the figure 8

three sectional views with ground and uncut main layer and the ratios of the respective material hardness.

Ways and execution of the invention

Figures 1 and 3 show a larger width grinding machine 1 in side view for double-sided grinding, e.g. 3. The coarse or calibration cut has been referred to as process section 2, two coarse sanding heads 4 and 5 or 4 'and 5' being provided at the top and bottom, which are provided with sanding belts 6 and 7 or 6 'and 7'. are equipped. In the rough grinding head 4, the grinding belt 6 (6 ') wraps around an upper grinding belt contact roller 8 (8') and a lower driven grinding belt contact roller 9 (9 ') in each case by approximately 180 °. In the second coarse grinding line 5, 5 ', the looping of the grinding belts 7, 7' is only about 90 °. Each of the grinding heads 4, 5 each have a strong cross member 10, 10 ', over which the grinding belt contact rollers on the machine stand 11, 11' are supported.

Each of the grinding belt contact rollers 9, 9 'has a base body 18 and is mounted according to Figures 1 and 3 on both sides via a stub shaft 12 in a pillow block 13 and is via a corresponding overdrive 14, each of its own drive motor 15, respectively. 16 driven. This can be a 50 to 150 hp engine in the usual sizes. The grinding belt contact rollers 9, 9 'are supported downwards or upwards on the machine frame 11 or 11'. The upper machine stand 11 rests on height-adjustable support columns 17, which may be formed as a hydraulic cylinder with piston 17 ', on the lower machine stand 11'. The height-adjustable support columns 17 serve primarily to adjust the gap width between the two grinding belt contact rollers 9, 9 '. The wide grinding machine further has on the Plattenzuführseite a first guide and feed unit 20 and a second guide and feed unit 21 on the Plattenabführseite. Both guide and feed units 20 resp. 21 consist of two pairs of guide rollers 22, wherein at least one roller of each guide and Vorschubeiheit can be formed as a driven feed roller 23. The guide and feed units 20 resp. 21 consist of an upper guide roller set 24 and a lower guide roller set 25, wherein the corresponding guide rollers 22, respectively. the corresponding feed rollers 23 give a stable longitudinal and transverse guidance. When commissioning for the first time or after longer periods of operation, the guide roller sets 24 and 25 must be precisely adjusted in height, so that the plate guides run exactly plane-parallel to the central loop plane 26 and are in an optimum position relative to the two sliding contact rollers. For this purpose, each guide roller set 24 resp. 25 set exactly on 27 setting.

The advancement section for the raw chipboard is designated by 29 according to FIG. 1 and comprises the feed unit 20 and 28. The black-filled roller respectively marks a feed roller which according to the new solution may have an abrasion-resistant and rough main layer applied by the thermal spraying method. It is important that the rough engagement of the feed rollers to the second coarse grinding may well leave intervention marks, as they are eliminated with the rough grinding. Completely different are the requirements for the guide units 22, 30 and 31, which may be formed as rubberized rollers. The bracket with reference numeral 40 denotes the process section for the fine grinding. In the figure 1, this fine grinding body 41 and 42 and 41 ', 42' each have a grinding shoe stage 43, respectively. 43 'up.

In FIG. 2, the fine grinding stage has two fine grinding rollers 44 or brushes 45.

FIG. 4 shows a counter-pressure shoe 50 with a supporting body 54 with a sliding plate 51 fastened thereto, which is held on the counter-pressure shoe by means of clamping means (not shown). The slide plate 51 has an abrasion-resistant and ground main layer 52 applied by thermal spraying (thick black line). The main layer can also be applied over the contours, which is taken with a graphite layer of the prior art. As the risk of damage to the main layer, especially due to the incoming Workpiece, is substantially lower, may also be sufficient, a flat application of the main layer with an inlet slope 53 and a minimal rounding.

FIG. 5 shows schematically advantageous control, control and regulation means for the whole process stage of grinding according to WO00 / 35628. Shown is a Kalibrierschleifkopf 4, 5 and a Feinschleifkopf 41, 42. A workpiece 3 is shown as a one side ground from above, flat plate 3. Die Schleifschleifkopf 4, 5 sind in der Zeichnung dargestellt. Prior to the grinding engagement, the plate 3 has a raw thickness Dr, after the first or calibration grinding a thickness D _K and after the fine grinding a thickness D _F. The difference in thickness between Dr and D _K is eg 0.4 mm; which corresponds to a grinding decrease of 0.4 mm. The grinding decrease during fine grinding is in the range of a few hundredths of a millimeter. After the calibration cut, a thickness measuring or thickness monitoring device Ds is drawn as the loop engagement monitoring device. About two feeler rollers, the plate thickness D _{K is} determined and forwarded the corresponding signal via a data bus bus. The calibration grinding head 4 and the fine grinding head are in the stand of the wide grinding machine STM, symbolized by a thick stroke stored. Simplified with HP is a height position signal generator shown by means of which the desired grinding removal can be determined. So that the desired grinding accuracy is even achievable, the workpiece or the plate 3 is performed multiple times. Corresponding single or double guide rollers and drive rollers, which are mounted in the machine, ensure the precise and constant conveying of the workpieces through the grinding line. The speed of passage of the plate 3 is detected via speed sensors V _PS . In the case of the calibration grinding head 4, the grinding belt speed V _KBS , the drive motor current A _K and A _F in the fine grinding head 41 can be determined. The height positioning of the abrasives can in practice take place in several ways, as mentioned above over the whole machine stand or eg via eccentric adjustment means of each of the grinding heads or on the calibration grinding head Hks and on the finishing head FHs. The said signals can be made available via the data bus bus of the control and control level, which consists of the three primary components machine control PLC, a recipe memory of a job and recipe input and a multi-size controller.

At present, only tentative monitoring techniques, as shown in Figure 5, used. Irrespective of the automation means, the corresponding parameters must be kept under control. Very important is the fact that with wide grinders usually not only a beautifully polished surface but rather a dimensional accuracy by a relatively large Schleifabtrag must be generated. Both are equally important, the surface quality and the thickness tolerance to be achieved. Both can only be optimally achieved economically if the corresponding interventions on elements or supporting bodies with the required dimensional accuracy and the required surface qualities are permanently ensured.

In the embodiment according to FIG. 5, opposite the grinding belt contact roller 9, there is a counterpressure roller 32 which, like the grinding belt contact roller, has a wear-resistant layer structure according to the invention.

FIG. 6 shows the grinding belt contact roller 9, 9 'with the various method steps from A to E.

A represents the raw state of the grinding belt contact roller at the end of the roll manufacturing. The rolls are produced in larger series and brought to the desired dimensional accuracy, the surface can change due to environmental influences. If, on the other hand, a protective layer is applied, it must first be completely removed from the thermal spraying process.

B shows the preparation of the abrasive tape contact roller for thermal spraying. The bright spots on the surface of the main body 18 symbolize the metallic whitish appearance of a smooth metal surface after a surface finish. For adhesion improvement, the cylindrical surface of the body is roughened by sandblasting, which is illustrated with the dark hue. Sand means sandblasting.

C The next step in the process is to apply a 0.1 to 2 mm thick aluminum bronze or, for example, a zinc substrate adhesive layer using the thermal spraying method. The thermal spraying process is known per se. FIG. 6 shows in simplified form the wire method. A spray head 60 has two mechanical wire feeders 61 and 62 which each feed a wire 63 or 64 continuously to an electrical ignition point 65. At the ignition point, the materials of the two wires are melted by the electric ignition heat. The two materials are already applied at the ignition point as intimately mixed, atomized particles by a primary air jet 66 and a secondary air jet 67 as a spray-shaped jet 68 on the base body, similar to the dye spray. During thermal spraying, the abrasive belt contact roller rotates in a controlled manner, as indicated by arrow 69. The axial movement, arrow 70, can either by appropriate movement in the direction of the axis of rotation 71 of the grinding belt contact roller 9, 9 'or by a controlled longitudinal movement of the spray head 60 done. With the appropriate movements and the order time, the desired layer thickness can be selected, which may be 0.1 to 0.2 millimeters in the case of the adhesive layer. After application of the thin adhesive layer, the surface roughness produced by the sandblasting is completely preserved and can even be increased, depending on the application technique, so that an ideal primer for the application of the main layer is produced.

D shows the thermal application of the main layer. The process is basically identical to the application of the adhesive layer, so that reference is made to it. In the main layer, the materials of the wires 63 ', 64' and also the layer thicknesses will usually be different than in the adhesive layer. A not unimportant aspect is that materials of different hardness are selected for the adhesive layer and for the main layer (FIGS. 7 and 8).

E shows the finished abrasive band contact roller for work use. With SF symbolically the generation of a final touch is shown as the last step of the process. With the desired finish, the surface gets a metallic shine again and is therefore brightly colored.

7 shows an example of the Schichtaubau a slightly more than 0.3 mm thick layer in cross section at different magnifications. In all three sections, the rough surface (upper edge) and the inhomogeneous porous structure are very clearly expressed. The dark as well as strongly greyish areas represent larger or a lot of smaller oxide inclusions, which make up the abrasion resistance. It can be seen that the surface roughness is of the order of about 0.1 mm. Already this roughness of 0.1 mm is in the thickness range of the whole order of the above-mentioned vacuum plasma spraying process of the prior art.

• Der Grundkörper besteht z.B. aus ST-52 und hat ein mittelgrosses Viereck.
• Die dünne Haftschicht besteht aus Aluminiumbronze und ist mit einem markant grösseren Viereck weich.
• Die Hauptschicht besteht aus 13%-igem Chromstahl und ist wesentlich härter als die beiden anderen Materialien.

FIG. 8 shows on the left in the picture two different magnifications with a square black marking, which reproduces the hardness of the relevant layer. The statement is qualitative. The bigger the square, the softer the material.

• The main body consists eg of ST-52 and has a medium-sized square.
• The thin adhesive layer is made of aluminum bronze and is soft with a significantly larger square.
• The main layer is 13% chromium steel and is much harder than the other two materials.

In the example according to Figure 8 is a grinding contact roller 9, 9 ', which must be ground finely after thermal spraying, which is indicated by the SF. It can be seen that about 0.1 to 0.2 mm of the main layer has to be removed. The material of the main body is denoted by the reference numeral 75, the adhesive layer by 72, the main layer by 73 and the finished abrasive surface by 74. The rough spots and spots are oxide particles.

Claims (11)

1. A method for improving the wear situation of supporting bodies in wide grinding machines (1), at least for the driven rolls (23) of the advancing unit (20) and/or the counter-pressure roll (32) and/or for contact rolls, wherein coating takes place, and

   a) an adhesive base (72) followed by

   b) a primary layer (73)

   are applied to a basic body of the supporting body, characterized in that the coating takes place via thermal spraying, wherein a composite layer is applied to the basic body (18, 51), consisting of an adhesive layer measuring about 0.1 to 0.3 mm, and an at least 0.3 mm thick wear-proof primary layer (73) applied via thermal spraying on top of the adhesive layer, wherein the primary layer (73) is designed as an inhomogeneous layer with oxide pockets, and the primary layer (73) consists of roughly equal percentages of chromium steel, in particular about 13% chromium steel, and wear-proof mechanically resistant material, and the primary layer (73) yields a raw, wear resistant surface with good grip.
2. The method according to claim 1, characterized in that the primary layer (73) for abrasive belt contact rolls (9, 9') preferably consists of about 13% chromium steel without mechanically resistant material, and the surface is ground following the thermal application of the primary layer (73) for generating a smooth surface.
3. The method according to claim 1, characterized in that the primary layer (73) for a counter-pressure shoe (50) of the supporting body is ground, and the layer structure is designed for a high surface slip.
4. The method according to claim 1, characterized in that the primary layer (73) is applied in the arc spraying process, and preferably exhibits a certain porosity.
5. The method according to one of claims 1 to 4, characterized in that the surface of the basic body (18, 51) is roughened prior to thermal application to improve adhesion, in particular via sandblasting.
6. The method according to one of claims 1 to 5, characterized in that the basic body (18, 51) is an oxidizable metal body, and the thermal layer application is performed within a limited time, in particular in less than 3 hours after surface roughening.
7. The method according to one of claims 1 to 6, characterized in that an adhesive layer (72) consisting in particular of aluminum bronze or zinc substrate is applied in a thermal spraying process to the basic body (18, 51) after it has been roughened before the primary layer (73) is thermally applied in the arc spraying process.
8. A supporting body for plates or abrasive belts (6, 7) in wide grinding machines (1), wherein at least one driven roll (9) of the advancing unit and/or a contact roll (8) and/or a counter-pressure shoe (50) and/or a counter-pressure roll (32) has a basic body (18, 51) made of plastic or metal (73) with a laminar structure, characterized in that the laminated structure consists of an adhesive layer (72) measuring about 0.1 to 0.3 mm, and an at least 0.3 mm thick outer, wear-proof primary layer (73) applied in a thermal spraying process, wherein the structure of the primary layer (73) exhibits oxide pockets and is inhomogeneous, and the primary layer (73) consists of roughly equal percentages of a chromium steel alloy and wear-proof mechanically resistant material, and the surface generated in the thermal spraying process is raw and wear resistant with good grip.
9. The supporting body according to claim 8, characterized in that the primary layer (73) of an abrasive belt contact roll (8) consists of chromium steel with a ground surface.
10. The supporting body according to claim 8, characterized in that the primary layer (73) is inhomogeneous, and exhibits a porous structure.
11. The supporting body according to one of claims 8 to 10, characterized in that the adhesive floor (72) is about 0.1-0.2 mm thick, and the primary layer (73) is applied with a thickness of about 0.4-5 mm, wherein the layer thickness in the case of the abrasive belt contact roll (8, 9) and/or the counter-pressure shoe (50) and/or counter-pressure roll (32) measures at least 0.3 to 4 mm after the surface has been ground.

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