EP0330680B1 - Reinforced pressing shell for a pressing device for treating strip materials, e.g. paper webs, and process and device for its manufacture - Google Patents

Abstract

PCT No. PCT/EP88/00386 Sec. 371 Date Jan. 5, 1989 Sec. 102(e) Date Jan. 5, 1989 PCT Filed May 6, 1988 PCT Pub. No. WO88/08897 PCT Pub. Date Nov. 17, 1988.An endless flexible press jacket for a press roll, a process for its fabrication and an apparatus upon which it is fabricated. The press jacket comprises a radially inner layer of elastomeric material which is provided with embedded layers of reinforcing yarns, an inner longitudinal layer of yarns extending under tension between the lateral ends of the endless tubular press jacket and a helical winding of peripheral yarns pretensioned and wrapped around the longitudinal yarns. The longitudinal yarns are held pretensioned radially above a casting mandrel and the casting nozzle moves along the axis of the casting mandrel delivering a helix of castable jacket material around the casting mandrel. At the same time, the later peripheral yarns are applied into the longitudinal yarns in the applied jacket material.

Description

The present invention relates to a press jacket (or a press belt) for a press device used for dewatering web-like material, preferably for an extended-nip press, comprising a roller and a pressure shoe with a sliding surface over which the press jacket slides and which is concave according to the diameter of the roller is shaped.

The invention also relates to a method and an apparatus for producing such a press jacket.

• gemäß US-PS 4,229,253
• gemäß US-PS 4,238,287 (Fig. 1)
• gemäß US-PS 4,552,620 (Fig. 5)
• gemäß DE-OS 32 35 468 (= GB 2,106,557 B) (Fig. 1) und
• gemäß VOITH-Veröffentlichung "Mehrschichtband" (Druckvermerk P 4022 K/0197 K/Sh/Srö -in der Bibliothek des Deutschen Patentamts am 26.07.1984 vereinnahmt)

in Verbindung mit Papierherstellungsmaschinen bekannt ist.The preferred field of application for such press sleeves is papermaking machines. The press device mentioned (with the press jacket) can be a so-called extended-nip press, such as, for example

• according to U.S. Patent 4,229,253
• according to US Pat. No. 4,238,287 (Fig. 1)
• according to US-PS 4,552,620 (Fig. 5)
• according to DE-OS 32 35 468 (= GB 2,106,557 B) (Fig. 1) and
• according to VOITH publication "Multilayer tape" (printed note P 4022 K / 0197 K / Sh / Srö - received in the library of the German Patent Office on July 26, 1984)

is known in connection with paper making machines.

US Pat. Nos. 4,229,253 and 4,238,287 relate to a press jacket for a press device used for dewatering web-shaped material. The pressing device is designed as an extended nip press and comprises a roller and a pressure shoe. The latter has a sliding surface over which the press jacket slides and which is concavely shaped in accordance with the diameter of the roller. The press jacket, which is endless in the running direction, consists of an elastomeric jacket material with reinforcing threads embedded therein. According to US '253 generally only a single layer of reinforcing threads is provided, namely so-called circumferential threads which extend substantially in the running direction and are arranged in a helical pattern. In addition, a layer of so-called longitudinal threads can be provided, which extend transversely to the running direction. According to US '287 a layer of peripheral threads is provided, which are sandwiched by two layers of longitudinal threads. The following is said about the manufacturing process in US ′ 253: "The uncured belt structure was then wrapped with a nylon tape and cured in open steam". Accordingly, an inner band or sheath layer is first covered with the reinforcing threads and then with an outer band or sheath layer; then the two layers are vulcanized together. There is therefore a risk that the bond between the two layers is imperfect or not sufficiently permanent.

According to US Pat. No. 4,552,620, the starting point is a fabric-like reinforcing insert which, due to the spirally wound circumferential threads, is endless or has been made endless by connecting the beginning and end. The production of the press jacket then comprises the following steps: pouring elastomeric material onto one side of the endless reinforcing insert and optionally smoothing the surface that has been created; then turn the product formed so far so that the smoothed surface is on the inside. The press jacket produced in this way (Figure 2 of US '620) has a rough outer surface because the threads of the fabric-like reinforcing insert partially protrude from the layer of the elastomeric material. The reinforcement insert is therefore susceptible to wear and the service life of the press jacket is therefore unsatisfactory. However, it is also known to produce a press jacket by additional pouring of elastomeric material on the other side of the reinforcing insert (and optionally by smoothing the second surface), the reinforcing insert according to Figure 3A of US '620 is completely embedded within the elastomeric material. However, the two-stage pouring of the two-layer elastomeric material is problematic. There is a risk that the bond between the two layers (for example due to inclusions) is imperfect and / or not sufficiently permanent.

The object on which the present invention is based is to improve a press jacket of the type described above in such a way that there is no risk of individual layers becoming detached from one another even over a long period of operation. But it should still be ensured that the reinforcing threads are completely embedded within the elastomeric material. Furthermore, the press jacket should be simpler and therefore cheaper to produce without having any qualitative disadvantages.

This object is achieved by the combination of features specified in claim 1.

In contrast to US '253 and' 287 and US '620 Fig. 3A, it is characteristic of the press jacket according to the invention that the elastomeric material layer is made from a single casting and cured with homogeneous crosslinking.

This manufacturing process described in more detail below presupposes that the longitudinal threads on the casting device in question must be stretched in the correct position before the casting process and that the peripheral threads are wound onto the longitudinal threads during the casting process. The finished press jacket according to the invention can thus be recognized by the following features: there are always two layers of reinforcing threads arranged one above the other, the longitudinal threads forming the inner layer and the peripheral threads forming the outer layer and the longitudinal threads extending over the entire (measured transverse to the direction of travel) Extend length of press sleeve; because during the casting process, the longitudinal threads must extend over the length of the press jacket to the clamping points.

According to the invention, the reinforcing threads lie completely within a thoroughly homogeneous elastomeric material layer. This enables the following advantages to be combined: both the risk of individual layers separating from one another and the risk of wear on the reinforcing threads are eliminated. Thus, the life of the press jacket is significantly increased compared to previously. The strength of the press jacket can be determined reproducibly on the basis of a defined tension between the longitudinal and the peripheral threads.

From DE 25 22 657 a roller is known, the deflection of which is adjustable. The roll shell of this roll is made of a rubber-like material and has an inner layer of wires that extend parallel to the roll axis for reinforcement, and also an outer layer of wires in the form of a metallic coil. This metallic coil should be relatively stiff in order to increase the circumferential rigidity of the roll shell. For this purpose, annular inserts can also be provided on the inside of the roll shell, which slide over the support elements (which serve to adjust the deflection). In this known roller is therefore for ensured that the roller jacket maintains its circular cross-sectional shape. In contrast, it is important in the press jacket according to the invention that it can adapt as easily as possible to changing radii of curvature of its career. In particular when sliding over the pressure shoe, it should adapt as easily as possible to its concave sliding surface. The press jacket according to the invention must therefore be as flexible as possible, which is why threads are provided for reinforcement, preferably threads made of polyamide or polyester.

Developments of the press jacket specified in claim 1 are the subject of claims 2 to 8. According to claim 8, the elastomeric material layer of the press jacket can be cast in multiple layers in a single operation.

The processes for producing the known press sleeves have already been outlined above. These methods are generally complex and - as already mentioned - also problematic in terms of strength. From DE-OS 33 18 984 a further method for producing an endless press jacket is known, in which a woven reinforcement band is clamped onto a cylinder and the elastomeric jacket material is poured in a helical shape. Here too, the press jacket must be turned over after being removed from the cylinder. Again, there is a disadvantage that the woven reinforcement tape is not completely wrapped within the elastomeric material. In other words: the reinforcement tape lies flush with the outer wall of the press jacket and is in turn susceptible to wear; it can be destroyed from the outside if individual threads of the reinforcement tape are pulled outwards.

The process-specific object on which the present invention is based is a method for producing the press jacket according to the invention described above specify, with which - in particular compared to the method known from DE-OS 33 18 984 - a press jacket can be manufactured which has two layers of reinforcing threads which are completely embedded in the jacket material, ie sufficiently with the two functional surfaces of the press jacket Sheath material are covered.

This process-specific problem is solved by the method steps specified in the characterizing part of claim 9, with the special precaution that the formation of a completely homogeneous elastomeric material layer is ensured by casting in a uniform step and air pockets are avoided from the outset.

Developments of this method defined in claim 9 are the subject of patent claims 10 to 16, wherein according to claims 12 to 15 process steps for removing the finished press jacket from the casting body and according to patent claim 16 a variant for applying the jacket material in more than one layer are specified .

The present invention is also based on the object of specifying a device for producing the press jacket according to the invention.

This object is achieved by the features and combinations of features specified in claims 17 to 21, the device in its general form being specified in claim 17. Claims 20 and 21 relate to device features associated with peeling a finished press jacket from the casting.

• Fig. 1 einen Ausschnitt aus einer Presse zum Entwässern von Papierbahnen mit einem über einen Druckschuh geführten Preßmantel;
• Fig.2a und Fig.2b einen Ausschnitt der Struktur des erfindungsgemäßen Preßmantels im Querschnitt und in Aufsicht, in jeweils geschnittener Darstellung;
• Fig. 3 einen Ausschnitt der Struktur des erfindungsgemäßen Preßmantels, der Umfangsfäden mit zueinander verschränkten flachgedrückten Abschnitten, sowie Nuten und Sacklöcher aufweist, in geschnittener Darstellung;
• Fig.4a und Fig. 4b einen Umfangsfaden der in Fig.3 gezeigten Art im Detail in zwei Ansichten, und zwar einmal in Längserstreckung und einmal in Schnittdarstellung;
• Fig. 5 eine Schnittdarstellung einer Vorrichtung zur Herstellung eines Preßmantels teils in Vorderansicht, teils im Querschnitt;
• Fig. 6 eine Schemadarstellung der Vorrichtung zur Herstellung eines Preßmantels im Längsschnitt nach Linie C-C der Fig. 5;
• Fig. 7a und Fig. 7b einen Ausschnitt der Schemadarstellung nach Fig.5 und 6 mit besonderer Darstellung der eingelegten Längsfäden und der eingegossenen Umfangsfäden,in zwei Ansichten, und zwar in Draufsicht (Fig.7a)und im Längsschnitt (Fig.7b);
• Fig. 8 einen Ausschnitt des Spannrings zur Fixierung der Längsfäden in Schnittdarstellung nach Linie D-D der Fig. 7b;
• Fig. 9 einen Ausschnitt des Längsfaden-Führungs- rings, in Schnittdarstellung nach Linie E-E der Fig. 7b ;
• Fig.10a und Fig. 10b eine Schemadarstellung zur Erläuterung des Abzeihens eines fertigen Preßmantels vom Gießkörper im Schnitt und zwar in zwei unterschiedlichen Verfharensstufen;
• Figf. 11 einen Ausschnitt eines hohlen Gießkörpers mit einem aufgeschrumpften Polyäthylen-mantel und über den Umfang verteilen Bohrungen in geschnittener Darstellung.

The invention is explained in more detail below with reference to the drawings. These show in

• 1 shows a section of a press for dewatering paper webs with a press jacket guided over a pressure shoe;
• 2a and 2b show a detail of the structure of the press casing according to the invention in cross-section and in supervision, each in a sectional view;
• 3 shows a section of the structure of the press cover according to the invention, which has circumferential threads with mutually flattened sections, as well as grooves and blind holes, in a sectional view;
• 4a and 4b a circumferential thread of the type shown in FIG. 3 in detail in two views, one in the longitudinal direction and one in the sectional view;
• Figure 5 is a sectional view of a device for producing a press jacket partly in front view, partly in cross section.
• Figure 6 is a schematic representation of the device for producing a press jacket in longitudinal section along line CC of Fig. 5.
• 7a and 7b show a section of the schematic representation according to FIGS. 5 and 6 with a special illustration of the inserted longitudinal threads and the cast peripheral threads, in two views, namely in a top view (FIG. 7a) and in a longitudinal section (FIG. 7b);
• 8 shows a detail of the tension ring for fixing the longitudinal threads in a sectional view along line DD of FIG. 7b;
• 9 shows a section of the longitudinal thread guide ring, in a sectional view along line EE of FIG. 7b;
• 10a and 10b show a schematic representation to explain the removal of a finished press jacket from the casting body in section, in two different process stages;
• Fig. 11 shows a section of a hollow casting body with a shrunk-on polyethylene sheath and bores distributed over the circumference in a sectional view.

In Fig. 1 - without a chair - a step of a press 1 for dewatering a (continuous) paper web 2 is shown. This press 1 consists essentially of an upper roller 3 and a lower roller 4, which in turn has a fixed core 5 in which a pressure shoe 6, which is pressed hydraulically against the upper roller 3, is guided. The fixed core 5 and the hydraulically mounted pressure shoe 6 of the lower roller 4 are encased by an endless (tubular) elastic press jacket 7, which consists of an elastomeric material with embedded reinforcing threads.

This press jacket 7 runs with its smooth inner surface sliding over the pressure shoe 6, which together with the top roller 3 forms an extended press zone 8 (extended nip press). The outside of the pressure shoe 6 is complementary to the diameter of the upper roller 3, i.e. the pressure shoe 6 has on its sliding surface a cavity corresponding to the diameter of the top roller 3.

To reduce the friction between the pressure shoe 6 and the press jacket 7, a device (not shown) for wetting the inner side of the press jacket 7 provided with lubricant.

The paper web 2 is fed between two so-called dewatering felts 9, 10 of the press zone 8 mentioned (arrow a). Due to the friction between the press jacket 7 sliding over the pressure shoe 6 and the drainage felt 10, the press jacket 7 is moved over the pressure shoe 6 (arrow b). The surface of the press jacket 7 can be suitable for absorbing water from the dewatering felt 10, specifically water that the paper web 2 has released to the dewatering felt 10 in the press zone 8. In this case, the outer surface of the press shell has 7 grooves and / or blind holes.

In the following, the press jacket 7 per se, as well as its manufacture will be explained in detail.

2a and 2b, the structure of the press jacket 7 is shown, namely once in a cross section (Fig. 2a) (analogous to the representation according to Fig.1) and the second in a view (Fig.2b) on one on the Level of the reinforcing threads cut open press jacket 7. The first-mentioned illustration - Fig. 2a - shows a cast press jacket 7 with a smooth inner surface and still unprocessed outer surface. The thickness of the press jacket 7 is selected in accordance with the intended use, for example very thick press jackets 7 could also be produced by a two-layer or multi-layer layer of cast-on jacket material 17. The press cover 7 according to FIG. 2a shows a constant distance of preferably 1 to 3 mm from the inside and a constant distance from each other a plurality of longitudinal threads 15 evenly distributed over the circumference. These form the inner layer of the reinforcing threads and give the press cover over the width the press zone considers the required dimensional stability. The distance from the inside of the press jacket 7 must be sufficiently large with regard to the wear layer; but it must also be so low that the necessary flexibility is maintained.

On the side of these longitudinal threads 15 facing away from the inside of the press jacket 7, circumferential threads 16 are provided, which represent the second layer of reinforcing threads. This position of the peripheral threads 16 is formed by winding a thread (or also several threads) along a screw line onto the longitudinal threads 15 and lies against the longitudinal threads 15 with prestress. Of course, this pretension must not be so great that the longitudinal threads 15 are deflected too close to the inner wall of the press jacket 7. The from longitudinal and Circumferential reinforcement inserts are always embedded in a uniform layer of the sheath material 17 in order to achieve a thoroughly homogeneous covering.

In the lower illustration - FIG. 2b - the detail according to FIG. 2a is drawn in a sectional illustration along the section line A-A. This section A-A runs along the "top" of the circumferential threads 16. The longitudinal threads 15 are aligned parallel to one another at a constant distance; the circumferential threads 16 are also parallel and equidistant from one another, however, according to the manufacturing process to be described later, at an angle to the outer edge of the press cover 7. The longitudinal threads 15 run (at least approximately) parallel to the axis of the cover (see FIG. 7b).

In Fig. 3, another embodiment for the inner structure and design of the press jacket 7 is shown. A longitudinal thread 15 runs parallel to the inner wall of the press jacket 7; across it, i.e. A plurality of circumferential threads 16 lie equidistantly on the longitudinal thread 15 perpendicular to the plane of the drawing. These circumferential threads 16 here consist of successively flattened sections which are alternately interlaced by 90 ° (see FIGS. 4a and 4b).

1, recesses, such as blind holes 18 and / or grooves 19 running in the circumferential direction (ie parallel to the circumferential threads 16) are machined from the outside of the press casing 7 into the casing material 17.

These blind holes 18 have a diameter of approximately 2 to 3 mm and a depth of approximately 2 to 10 mm. The areal share of the total outer surface of the press jacket 7 should be approximately 15 to 30%.

The grooves 19, which are additionally or alternatively incorporated into the blind holes 18, have a width of approximately 0.4 to 0.8 mm and have a depth of approximately 1 to 3 mm.

It is important with regard to these blind holes and the grooves that the reinforcing threads are not damaged so that press water cannot destroy the inside of the jacket.

In Fig. 4, a circumferential thread 16 of the special type used in the example of Fig. 3 is shown in two views, once in the longitudinal extension (Fig. 4 a) and once in section B-B (Fig. 4 b). This circumferential thread 16 consists of alternating successive, flattened thread sections 20 which are interlaced with one another in such a way that a sequence of sections aligned perpendicular to one another is produced. This special design of the circumferential threads 16 achieves a substantially better positive fit between the circumferential threads 16 and the jacket material in the cast press jacket 7. The threads are thus optimally fixed and the press jacket 7 is given optimum shape and dimension stability.

In general, this form fit is the better, the more irregularly the circumferential threads 16 are formed along their extension. Cross-sectional changes in general, equidistantly applied bruises with remaining round cross sections between these bruises and alternating, entangled bruises according to the example 4 ensure a high form fit between the reinforcing threads and the jacket material. Depending on the concept, the circumferential threads, the longitudinal threads or both types of reinforcing threads can be provided together with cross-sectional changes of the aforementioned type.

The reinforcement threads themselves are so-called monofilaments, i.e. threads not twisted, or they each consist of 2 to 6 monofilament single threads, which are twisted together. In a special embodiment, one type of reinforcing thread can also be monofilament and the other type twisted. With the monofilament threads, air pockets and mutual rubbing of the threads are avoided from the outset. But even with the reinforcement threads twisted from 2 to 6 monofilament threads, the gaps are so large that the sheath material can penetrate well and well.

The reinforcing threads consist of polyamide or polyester because of the strength and processing properties, in particular in the constellation that the longitudinal threads - in terms of elasticity - are made of polyamide and the circumferential threads - in terms of dimensional stability - are made of polyester. Polyurethane is preferably chosen as the elastomeric sheath material because of its high wear resistance.

The manufacture of a press jacket 7 of the type described above is explained in more detail below with the aid of the device for its manufacture.

5 shows a basic illustration of the overall device. This overall device consists of two Functionally coordinated basic units, a support 26 which can be moved longitudinally on a fixed machine table 25 and a casting body 28 which is rotatably mounted in fixed end shields 27. In the example shown, this is designed as a hollow cylinder which is rotated about its axis via drive means (not shown) rotary drive means and the translatory drive means for the support 26 - indicated by a spindle drive 29 - are coordinated with one another. A specific stroke of support 26 corresponds to a specific angle of rotation of casting body 28.

This support 26, which can be moved, for example, via the spindle drive 29 perpendicular to the plane of the drawing in the guide rails 30, carries, as shown in FIG. 5, the unit 31 for the preparation and supply of the elastomeric castable jacket material and on the other hand a device 32 for dispensing the Circumferential thread 16 (or the peripheral threads).

The unit 31 for the preparation and supply of the jacket material consists of two storage containers 33 for the components of the jacket material, a mixer 34 for these components, a feed line 35 and a pouring nozzle 36 for delivering the jacket material to the surface of the casting body 28. The said unit 31 determining elements are mechanically rigidly connected to the support 26 and are consequently moved with it in a translatory manner. The pouring nozzle 36 is preferably positioned so that it is above the casting body 28, preferably slightly offset to the side.

The device 32 for delivering the (at least one circumferential thread 16) consists of one (or more) thread roller (s) 37 from which the peripheral thread 16 can be pulled off. This thread roller 37 is also firmly connected to the support 26. On the path of the peripheral thread 16 A guide device 38 for the or the unfair threads 16 is arranged between the thread roll 37 and the casting body 28. In this guide device 38, the circumferential threads 16 lying next to one another are positioned axially at the correct distance from one another.

The system described so far will now be explained on the basis of its mode of operation in connection with the production of a press jacket 7.

Before the system shown in FIG. 5 is started up, the casting body 28 is first prepared, to the extent that 28 longitudinal threads 15 are stretched over the entire circumference at a uniform distance from one another and at a respective uniform distance from the surface of the casting body. These longitudinal threads 15 lie parallel to one another and thus form a coaxial cage arrangement over the circumference of the casting body 28.

The beginning of the circumferential thread 16 is then fixed on an end face of the casting body 28.

Now the casting body 28 is rotated (arrow w). At the same time, the pouring nozzle 36 is opened and the support 26 is moved linearly. The elastomeric jacket material 17 flows onto the surface of the casting body 28 with the stretched longitudinal threads 15 and forms a coaxial press jacket layer on the casting body 28 now the circumferential thread 16 is simultaneously wound up, preferably under a certain pretension. This pretension is dimensioned such that the circumferential thread 16 rests tensioned on the longitudinal threads 15 and even deflects them slightly towards the surface of the casting body 28.

With the rotation of the casting body 28 and the pouring of the jacket material 17, as already mentioned, the support 26 is simultaneously moved linearly. So that the press jacket is formed from a helical (= helix) -like strand of liquid material 17. At the same time, the circumferential thread 16 is wound up on a cage arrangement in the manner of a screw line (= helix). As a result, the peripheral thread 16 is introduced into the still liquid material 17 and fixed therein with the solidification of the jacket material 17.

5, half of the first turn of the material 17 is cast. This beginning of the press jacket 7 is closed by continuing the casting process and the winding process for the circumferential thread 16 and continued over the length of the casting body 28 - up to its second end.

FIG. 6 shows a schematic representation of the system shown in FIG. 5 in a top view, specifically in section C-C according to FIG. 5.

The longitudinal threads 15 are tensioned on the rotating (arrow w) cast in the bearing plates 27, namely - in the simplest case shown - over tensioning rings 40 which are supported on the end faces of the cast body 28. The support becomes parallel to the axis of the cast body 28 26 in the guide rails 30 (arrow s). The support 26 carries two thread rollers 37 for unwinding two primary threads 16 and a casting nozzle 36.

With simultaneous rotational movement of the casting body 28 and translatory (axially parallel) movement of the support 26, a layer of elastomeric jacket material 17 is thus poured on in a helical manner; the circumferential threads 16 are simultaneously wrapped in this layer, which are thus also helically drawn over the longitudinal threads 15.

In the drawing of Fig. 6, about a third of a press jacket 7 is cast.

6 additionally shows a further embodiment of the invention. Press shells of large thicknesses are required for certain applications; Such material thicknesses can generally not be ejected by means of a single pouring nozzle 36.

Fig. 6 shows a second pouring nozzle 36 'to solve this problem, which is also rigidly connected to the support 26 and thus synchronously, namely the (first) pouring nozzle 36 lagging, is moved along the casting body 28. With this second pouring nozzle 36 ', a second layer of jacket material 17' can thus be poured on. It is essential that the reinforcement of the press jacket 7 consisting of longitudinal threads 15 and circumferential threads 16 is fully embedded in the first layer of jacket material 17, so that a complete connection between the jacket material and the reinforcing threads is ensured.

7 shows a detail of the surface of the casting body 28 in two views. (Fig. 7a and Fig. 7b).

7a shows the arrangement and assignment of the longitudinal threads 15, which are drawn in a meandering manner between two tensioning rings 40a / 40b back and forth along the jacket of the casting body 28. Each of the clamping rings 40a / 40b consists of a cuff-shaped ring 41 which has lugs 42 distributed over the circumference. These lugs 42 determine the spacing of the longitudinal threads 15 with respect to one another and their spacing from the surface of the casting body 28 a flange shoulder 43, via which this clamping ring 40a rests on the end face of the casting body 28. The upper second clamping ring 40b is loosely seated on the casting body 28 and is connected to a radially outwardly directed peripheral projection 44 which in turn can be clamped via a screw connection 45 and a flange 46 which is supported on the second end face of the casting body 28.

Said screw connection 45 is loose for inserting the longitudinal thread 15 and for hanging onto the lugs 42 of the two tension rings 40a / b. If the longitudinal thread 15 is hooked over the entire surface of the casting body 28 into the lugs 42 and these thread strands form a closed cage between the tensioning rings 40a / b, the tensioning ring 40b loosely seated on the casting body 28 is tightened towards the front side via the screw connection 45 . So that the longitudinal threads 15 are tensioned.

With regard to the circumferential threads 16 drawn over the longitudinal thread 15, which run helically, ie obliquely in FIG. 7, it is conceivable to twist the two tension rings 40a / b against each other to such an extent that the longitudinal threads 15 also run obliquely and then form an orthogonal grid pattern with the peripheral threads 16.

The side view of Fig. 7, i.e. 7b, it can be seen that the pouring nozzle 36 has already progressed to over half the width of the press jacket 7 to be produced along the surface of the casting body 28. Until then, the circumferential thread 16 is spirally inserted into the jacket material 17 and drawn onto the longitudinal threads 15.

In order to avoid with certainty that the longitudinal threads 15 are pressed onto the casting body 28, for example when the jacket material 17 is poured on or when the peripheral thread 16 is pulled on, i.e. In order to ensure the spacing of the longitudinal threads 15 from the casting body 28, a longitudinal thread guide ring unit 47 is provided, which is moved in advance in synchronism with the casting nozzle 36 (arrow s).

This longitudinal thread guide ring unit 47 consists of a spacer ring 48 which lies between the surface of the casting body 28 and the longitudinal threads 15, and a comb-like ring 49 which has grooves corresponding to the spacing of the longitudinal threads 15 from one another. This guide ring unit 47, consisting of the spacer ring 48 and the comb-like ring 49, is connected to the support 26 via a guide device (not shown).

With this longitudinal thread guide ring unit 47, the longitudinal threads 15 are thus aligned over the entire circumference of the casting body 28. The pouring jet of the jacket material 17 coming from the pouring nozzle 36 thus fixes these longitudinal threads 15 in their correct position and orientation, whereby it should be noted for the sake of clarity that the longitudinal thread guide ring unit 47 executes a linear movement with respect to the casting body 28 and with the casting body 28 turns together.

8 shows a section of the (lower) clamping ring 40a according to section line D-D according to FIG. 7b. From this illustration, the cuff-shaped ring 41 can be seen, which rests on the jacket of the casting body 28 and has a sequence of lugs 42 distributed over the circumference, between which there are grooves. Through these grooves, the longitudinal threads 15 are drawn, which are looped around every second nose 42.

A section of the longitudinal thread guide ring unit 47 is shown in FIG. 9 along the section line E-E according to FIG. 7b. This consists of the spacer ring 48, which rests on the surface of the casting body 28 and supports the longitudinal threads 15 or keeps them at a distance from the casting body. The spacer ring 48 is preceded by the comb-like ring 49, which has grooves 50 corresponding to the distance between the longitudinal threads 15, by means of which the comb-like ring 49 is placed on the casting body 28 via the longitudinal threads 15.

The comb-like ring 49 is constructed in several parts, the parts being able to be clamped to one another via screw connections 51. This makes it possible for the ring 49 to be assembled after the longitudinal threads 15 have been tensioned.

With regard to the design of the longitudinal thread guide ring unit 47, it is also conceivable to provide the spacer ring 48 with a circumferential web and grooves corresponding to the longitudinal threads 15 and to cover this spacer ring simultaneously with the winding of the longitudinal threads 15.

The removal of a finished cast press jacket 7 will be explained on the basis of the process stages shown in FIGS. 10a and 10b.

A clamping ring is fitted onto each of the two end regions of the press jacket 7. One clamping ring 53 is firmly connected to the press jacket 7 and dimensioned relative to the casting body 28 so that it can be pulled lengthwise with the press jacket 7, but seals the gap between the press jacket 7 and the casting body 28 well. The second clamping ring 54 is designed such that it remains stationary relative to the casting body 28 and enables the press jacket 7 to slip or pull through. The second clamping ring 54 should also press the press jacket 7 as close as possible to the casting body 28. (Fig. 10a)

If a fluid is pressed into the area of the joint between the press jacket 7 and the casting body 28 via a feed line 55 leading through the casting body 28 or its wall, this fluid is distributed in this parting line in the manner of an air cushion and the press jacket 7 can be moved by means of a pull ring 56 are deducted. The first clamping ring 53 moves together with the press jacket 7 along the casting body 28 until it strikes the second clamping ring 54 and the press jacket 7 is completely free. This removal is facilitated in that the casting body 28 is coated with a material which reduces the adhesion before the coating of the jacket material. (Fig.10b).

According to FIG. 11, a further possibility for pulling off a press jacket 7 cast on a casting body 28 is conceivable.

The casting body 28 is a hollow cylinder. On this hollow cylinder is a 17 before pouring the jacket material Polyethylene sheath 57 shrunk. If a fluid is now pressed in through holes 58 provided in the wall of the hollow cylinder, a sliding layer is formed in the parting line between the casting body 28 and the polyethylene jacket 57 and the press jacket 7 can be removed together with the polyethylene jacket 57.

In principle, it is also conceivable to coat the casting body 28 with a material which prevents the adhesion of the jacket material and then to expand and remove the press jacket 7 from the inside by heat treatment or through bores in a hollow cylindrical casting body.

Ultimately, the above-described method and the device for carrying out this method can be used to produce a press jacket which is relatively inexpensive to produce, since the steps of weaving, making endless and heat-setting a fabric are not necessary, and in principle with a single casting process a stable press jacket can be achieved. In particular, because it is not necessary to turn the finished press jacket, relatively thick jackets can be produced - possibly also by multi-layer casting. In this context, it is particularly important that the reinforcement, i.e. the reinforcement lies securely within the press casing and is therefore protected against wear and destruction.

Finally, it should also be noted that the outer surface of the press shell usually has to be smoothed after casting. Possibly. must - cf. Fig. 3 - also blind holes and grooves for Water absorption can be incorporated. As far as the inside of the press jacket is concerned, it should be noted that it can remain unprocessed.

Claims (21)

1. Press jacket for a press unit for the dewatering of web-like material, especially for use on an extended-nip press, comprising a roll (3) and a pressure shoe (6) with a sliding surface over which the press jacket (7) slides and which is shaped concave in accordance with the diameter of the roll (3), with the following features:

a) the press jacket (7) endless in the direction of travel is formed from an elastomeric jacket material (17) in whose interior are embedded reinforcement threads (15, 16) in two layers arranged one above the other;

b) one layer is formed by yarns (hereinafter called longitudinal yarns 15) extending mainly at right angles to the direction of travel;

c) another layer is formed by reinforcement yarns (hereinafter called peripheral yarns 16) running mainly in the peripheral direction, which are arranged in the form of at least one helical line;

d) the longitudinal yarns (15) form the inner layer and the peripheral yarns (16) form the outer layer of the reinforcement yarns;

e) the longitudinal yarns (15) extend over the entire (measured at right angles to the direction of travel) length of the press jacket (7);

f) the elastomeric material layer (17), which encases the reinforcement yarns on all sides, is manufactured from a single casting and cured by homogeneous cross linkage.

2. Press jacket according to claim 1,
characterized in
that the longitudinal yarns (15) are arranged preferably parallel to one another at a pre-determined distance from the inside of the press jacket (7), and that the peripheral yarns (16) rest positively on the longitudinal yarns (15) (Figs. 2a and 2b).

3. Press jacket according to one of claims 1 or 2,
characterized in
that the longitudinal yarns (15) are arranged at a distance of 1 to 3 mm from the inner wall of the press jacket (7) (Figs. 2a and 2b).

4. Press Jacket according to one of claims 1 to 3,
characterized in
that - for use in a press for the dewatering of a paper web, with blind holes being worked into the jacket wall from the outside wall - the blind holes (18) have a diameter of approx. 2 to 3 mm, a depth of approx. 2 to 10 mm and are arranged at a distance from one another so that the portion of the hole cross-sections relative to the jacket surface is approx. 15 to 30 %.

5. Press Jacket according to one of claims 1 to 4,
characterized in
that the longitudinal yarns (15) and/or the peripheral yarns (16) have a changing cross-section over their length (Figs. 4a and 4b).

6. Press Jacket according to claim 5,
characterized in
that the cross-sectional change consists in an alternation of round and flat-pressed yarn portions.

7. Press jacket according to claim 5,
characterized in
that the cross-sectional change consists in an alternation of flat-pressed yarn portions (20) whose cross-sectional areas are each aligned approximately perpendicularly to one another (Figs. 4a and 4b).

8. Press Jacket according to one of claims 1 to 7,
characterized in
that the jacket material (17) is cast in more than one layer, with the first (internal) layer completely enclosing the reinforcement yarns (15, 16) and the other layer(s) is cast according to the thickness of the press jacket (7) (Fig. 6).

9. Process for the manufacture of a press jacket according to one of claims 1 to 8,
characterized in
that the longitudinal yarns (15) are tensioned in the pre-determined arrangement relative to one another, before casting of the jacket material (17), onto a casting body (28), especially a casting mandrel, at a pre-determined distance from the casting body (28), that the jacket material (17) is cast in the form of a helical line on the casting body (28) in-between the longitudinal yarns (15) and that at the same time the peripheral yarns (16) are wound into the jacket material (17) with the casting-on of the jacket material (17) (Figs. 5, 6, 7a and 7b).

10. Process according to claim 9,
characterized in
that to maintain the distance between casting body (28) and longitudinal yarns (15) ahead of the casting zone of the jacket material (17) a longitudinal yarn guide ring (47) is moved together axially and namely with the advancing speed of a casting nozzle (36) and of a peripheral yarn feed unit (32) (Figs. 7a and 7b).

11. Process according to claim 10,
characterized in
that by means of the longitudinal yarn guide ring (47) the longitudinal yarns (15) are fixed in their distance from one another and supported radially so that on fluctuations of the tension of the peripheral yarns (16), the distance of the longitudinal yarns (15) from the casting body (28) remains mainly constant.

12. Process according to one of claims 9 to 11,
characterized in
that for removal of the press jacket (7) the surface of the casting body (28) is coated with a material preventing adherence and the press jacket (7) is warmed up from the inside and/or outside by 50 to 150 K to enlarge the periphery.

13. Process according to one of claims 9 to 12,
characterized in
that for removal of the press jacket (7) a fluid is pressed in under pressure between this and the casting body (28) so that the press jacket (7) expands and can be pulled off axially (Figs. 10a, 10b and 11), whereby it is preferably provided for that the fluid is pressed in at one end of the press jacket (7) from inside through the casting body (28), that the press jacket (7) is pressed together at both sides by one clamping ring each (53, 54) until only little fluid can escape, and that the press jacket (7) is then pulled off towards the side of the fluid supply (55), with the first clamping ring (53) lying away from the fluid supply being moved along with the press jacket (7), and the second clamping ring (54) firmly held stationary relative to the casting body (28), by means of which the press jacket (7) can be pulled through the second clamping ring (54) (Fig. 10a/b).

14. Process according to claim 13,
characterized in
that the second clamping ring (54) is an endless flexible toroidal axially guided roll whose internal diameter is approximately equal in size to the outside diameter of the press jacket (7).

15. Process according to one of claims 9 or 10,
characterized in
that for removal of the press jacket (7) from a casting body (28) being hollow on the inside and being provided with small holes (58) in the wall distributed over the periphery, onto which is shrunk a polyethylene jacket (57) of approx. 0.1 to 2 mm thickness, a fluid pressure is generated (Fig. 11) between casting body outer surface and polyethylene jacket (57) (Fig. 11).

16. Process according to one of claims 9 to 15,
characterized in
that the jacket material (17) encasing the reinforcement yarns (15, 16) is cast on in a first layer and the jacket material (17′) determining the thickness of the press jacket (7) is cast on in at least one further layer on the casting body (28) (Fig. 6), whereby preferably the layers of the jacket material (17, 17′) are cast with offset casting nozzles (36, 36′) directly after each other (Fig. 6).

17. Device for the production of a press jacket according to one of claims 1 to 16,
characterized in
that an axially-symmetrical casting body (28) corresponding to the shape of the press jacket (7) and rotatable via drive means is provided, which has one tensioning ring (40) each at the two ends corresponding to the length of the longitudinal yarns (15), that at least one casting nozzle (36) movable parallel to the axis of the casting body (28) is provided for the jacket material (17), that at least one feed unit (32) movable parallel to the axis of the casting body (28) is provided for the peripheral yarns (16), and that the drive means for the casting body (28) and for a support (26) carrying the casting nozzle (36) are so coordinated that on the turning of the casting body (28) the support (26) is moved in such a way that the jacket material (17) is applied in the form of helical lines continuously following one another and the peripheral yarns (16) at the same time are also pulled in in the form of helical lines into the jacket material (17) (Figs. 5, 6, 7a and 7b).

18. Device according to claim 17,
characterized in
that the casting nozzle (36), the feed unit (32) for the peripheral yarns (16) and a guide unit for the longitudinal yarn guide ring (47) are fastened jointly to the support (26) moved axially parallel to the axis of the casting body (28) (Figs. 5, 6, 7a and 7b).

19) Device according to claim 18,
characterized in
that the longitudinal yarn guide ring (47) is made multi-sectional so that the outer part can be installed after tensioning of the longitudinal yarns (15) (Fig. 8).

20. Device according to one of claims 17 to 19,
characterized in
that for pulling off the press jacket (7) from the casting body (28) at least one fluid supply duct (55) is provided at the end of the casting body (28) going to the parting surface between casting body (28) and finish-cast press jacket (7), and that at this end of the casting body (28) a second clamping ring (54) unmovable relative to the latter and at the other end a first clamping ring (53) unmovable relative to the press jacket (7) are provided (Figs. 10a and 10b).

21. Device according to one of claims 17 to 20,
characterized in
that the casting body (28) is a hollow cylinder, that a polyethylene jacket (57) is shrunk onto the hollow cylinder, that the hollow cylinder has a multiplicity of small holes (58) distributed around the periphery, and that the interior of the hollow cylinder is pressurizable through its end face with a fluid under pressure (Fig. 11).

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