EP0036176B1 - Device for exterting a surface pressure on workpieces in movement - Google Patents

Description

The invention relates to a device for applying a surface pressure to progressive workpieces as defined in the preamble of claim 1.

The features from the preamble of claim 1 in the version for the contracting states FR, GB, IT, NL and SE are from EP-A-26 401 published on April 8, 1981, which is a document according to Article 54, Paragraph 3 EPC represents, known.

The features from the preamble of claim 1 in the version for the contracting states AT, BE, CH and LI are known from DE-A-2 735 142.

In devices for applying a surface pressure to progressive workpieces, it has hitherto also been known to provide a single pressure chamber above or below a workpiece passing through on the top or bottom, which covers approximately the entire width of the progressive workpiece. Large pressure chambers of this type, which are acted upon by a pressure medium such as compressed air, have various disadvantages. The sealing strips or strips directed in the direction of the press belt on the open side of such a pressure chamber are stressed considerably more in the direction of passage of the workpiece than the seals transverse to the direction of passage. This leads to different wear and tear and premature wear and also to air loss.

Due to the large length of the sealing strips, this seal cannot be made in one piece. There are one or more joints that also lead to leaks or pressure losses. Large forces caused by the pressure medium act on the sealing strips, so that these strips have to be supported, but this is only possible with great design effort. If there is a sudden sudden loss of pressure, the workpiece presses the press belt against the inner surfaces of the pressure chambers. There is considerable wear and tear if these inner surfaces are not covered with special sliding material. These precautions, which are only required to achieve emergency running properties, are complex and difficult to carry out.

From DE-A-2 536 476 it is known to provide a plurality of closed pressure chambers in a row and in a transverse arrangement. These pressure chambers each consist of two cup-shaped parts that lie radially one inside the other. They form an inner chamber that can be filled with pressure medium, so that there is one piston-cylinder unit. These closed pressure chambers do not act directly on a press belt, but only indirectly via roller chains.

The invention has for its object to provide a device in which the seals are formed without joints or joints and executed without complex supports, and have good emergency running properties. The sealing strips should be easy to replace. In addition, the pressure chamber should be able to be easily adapted to different workpiece widths. The continuous workpiece is also intended to directly control the pressure medium flowing into the many outer pressure chambers and thus the movement of the many inner sockets which occasionally attach to the press belt, independently of one another and on the other hand from any shape (width, length) and Throughput speed of the individual workpieces.

This object was achieved according to the invention by the measures in the characterizing part of claim 1.

In the version for the contracting states FR, GB, IT, NL and SE, these measures consist in the fact that the screw part of the pressure chamber has a central blind hole extending from the pressure plate and several radial holes connecting the central hole to the inner pressure chamber, so that in the event of a pressure drop in the outer pressure chamber due to the escape of compressed air, the force resulting from the pressure forces of the inner pressure chamber and the outer pressure chamber, the inner frame with the sealing strips pushing on the passband, becomes greater. The invention thus consists in the arrangement of a throttle connection between the inner and the outer pressure chamber.

In the version for the contracting states AT, BE, CH, LI, the measures according to the invention consist in the fact that a large number of small pressure chamber units, which are arranged on the effective pressure surface of the press belt and are arranged transversely to the direction of travel and can be switched on and off to adapt to the width of the workpiece, are provided , each designed in its basic form as a round body with a circular base area and divided into two pressure chambers by an outer frame attached to a common pressure plate and an inner frame concentric with it, perpendicular to the press belt, which are arranged axially one behind the other and one inner and one represent the outer pressure chamber, a distance being maintained between the outer frame and the inner frame, which is bridged by a rubber-elastic sealing ring.

Advantageous further developments are set out in the dependent claims.

The sealing problem can be solved particularly advantageously by a large number of small pressure chambers. Such pressure chambers with a circular basic shape, that is to say as cylinder sections, can be produced very advantageously. The circular weather strips can be made in one piece. without joints. Due to its advantageous shape, the seal is well supported on all sides and premature wear is avoided. Since the ring surfaces are relatively small, their surfaces can be machined very precisely. Difficulties due to machining inaccuracies that occur with previous seals are eliminated. Small sealing strips can also be easily replaced. By simply lining up other smaller pressure chambers, the total effective pressure areas on the press belt can be widened or lengthened depending on the desired press area size. The same components can be used again and again. It is also possible to combine the small pressure chambers in rows, which are adjacent to each other in the direction of passage of the press belt and each are pressurized separately (in rows). As a result, different pressures across the width of the pressure surface (press surface) and a different effective usable width of the press surface can be produced with simple means.

In a preferred embodiment, a shut-off device, which temporarily separates the pressure medium supply from the inner pressure chamber into the outer pressure chamber, is provided between the two pressure chambers.

Such a shut-off device makes it possible for the associated shut-off device to open each time the workpiece arrives and thus a corresponding lifting of the press belt and thus one or more inner sockets of individual pressure chambers, and pressure medium not only constantly presses the inner pressure chamber but also temporarily presses the outer pressure chamber, so that the press belt in the area of this outer pressure chamber is also pressed against the workpiece by the pressure medium. This control of each individual external pressure chamber, which lies in the area of the surface of the workpiece passing through, acts immediately (i.e. without delay) and can detect all pressure chambers.

If the workpiece has passed through, this shut-off device blocks the pressure medium supply to the outer pressure chamber with the movement of the inner holder in the direction of the press belt, so that the latter is largely depressurized and no pressure medium can also escape laterally in a disadvantageous manner.

It is irrelevant which contour the workpiece runs through and whether several smaller workpieces of different contours also run at the same time. The pressure chambers, which are in the area of the surfaces of these workpieces, are continuously pressurized or relieved, as described above, so that the pressure belt is pressed only in the area of the moving surface of the work piece or pieces. Pressure losses are largely avoided by such a direct and precise control.

In this embodiment according to the invention, the loading of the outer pressure chamber changes in accordance with the respective (temporarily) effective width of the pressure surface (in accordance with the width of the workpiece passing through).

In a preferred embodiment, this shut-off device is designed as an O-sealing ring, which is arranged between the annular space, which is left between the inner positionally variable frame and the fixed holding part, and a gradation of the holding part.

In a modified embodiment according to the invention, the holding part has further transverse bores, so that the fixed holding part controls the flow of the pressure medium as a function of the variable position of the inner socket of each pressure device, as in the case of a control piston.

Preferred embodiments of the invention are contained in the protective claims.

• Fig. 1 eine Unteransicht vieler zylinderförmiger Druckkammern, die an einer Druckplatte angeordnet sind;
• Fig. 2 einen senkrechten Schnitt gemäß Linie 11-11 der Fig. 1;
• Fig. 3 eine vergrößerte Darstellung der in Fig. 2 geschnitten dargestellten Druckkammer;
• Fig. 4 einen Schnitt durch eine anders ausgeführte Druckkammer;
• Fig. 5 einen senkrechten Schnitt durch eine abgeänderte zylinderförmige Druckkammer;
• Fig. 6 einen senkrechten Schnitt durch dieselbe Druckkammer mit Absperrvorrichtung nach Fig. 5 in entlasteter Stellung;
• Fig. 7 einen senkrechten Schnitt durch dieselbe Druckkammer mit Absperrvorrichtung in beaufschlagter Stellung;
• Fig. 8 einen senkrechten Schnitt durch dieselbe Druckkammer mit weiter abgeänderter Absperrvorrichtung in entlasteter Stellung;
• Fig. 9 einen senkrechten Schnitt durch dieselbe Druckkammer mit Absperrvorrichtung in beaufschlagter Stellung.

Embodiments of the invention are shown in the drawing and are described in more detail below. Show it:

• Figure 1 is a bottom view of many cylindrical pressure chambers which are arranged on a pressure plate.
• Fig. 2 is a vertical section along line 11-11 of Fig. 1;
• Fig. 3 is an enlarged view of the pressure chamber shown in section in Fig. 2;
• 4 shows a section through a differently designed pressure chamber;
• Figure 5 is a vertical section through a modified cylindrical pressure chamber.
• 6 shows a vertical section through the same pressure chamber with shut-off device according to FIG. 5 in the unloaded position;
• 7 shows a vertical section through the same pressure chamber with shut-off device in the acted upon position;
• 8 shows a vertical section through the same pressure chamber with a further modified shut-off device in the unloaded position;
• Fig. 9 is a vertical section through the same pressure chamber with shut-off device in the loaded position.

The device according to the invention consists of a lower frame and an upper frame, in each of which endless press belts 10 are installed. These press belts are stretched on pulleys and can be driven by them. They are arranged with a gap to each other that corresponds to the width of a workpiece to be machined. While the press belts 10 carry out a horizontal movement with their surfaces touching the workpiece, the workpiece is drawn into the gap between these surfaces and the surfaces of the press belts 10 apply pressure there. When the workpiece passes through this device, it is processed so that it leaves the gap between the press belts 10 at the outlet as a finished workpiece.

In this way, films can be pressed onto the top and bottom of workpieces, which run off supply rolls. Such a pressing process can take place at room temperature, but it can also simultaneously provide the application of high temperatures to the workpiece in the machining area. The desired pressure can be applied as air pressure, which acts in the pressure chambers, which are each arranged on the back of the press belt 10 in relation to the workpiece, that is to say on the surface of the press belt 10, which is not in contact with the workpiece.

The pressure chambers are arranged on a common pressure plate 11. Each pressure chamber is formed by an outer socket 12 or 13. The outer socket 12 or 13 is held on the pressure plate 11 by means of a screw part 16 or 17 which is screwed into a threaded hole 18 or 19 of the pressure plate 11. Each pressure chamber is divided by the inner socket 14 or 15 into an inner pressure chamber 20 or 21 and an outer pressure chamber 22 or 23.

The outer frame 12 and 13 and the inner frame 14 and 15 are arranged concentrically to each other. On the press belt 10 there is an annular seal 24 or 25 which is held by the inner frame 14 or 15. 3, 6, 7 and 9 of the drawing, the seal 24 is inserted into a recess in the inner socket 14. According to FIG. 4 of the drawing, the seal 25 is fastened to a guide ring 26 which concentrically surrounds the inner socket 15 and which is supported on a flange 27 formed on the inner socket 15. An elastic sealing ring 28 or 29 bridges the distance between the inner socket 14 or between the guide ring 26 and the outer socket 12 or 13 surrounding it. The inner socket 14 with the seal 24 can thus be slightly insignificant relative to the outer socket 12 move. The guide ring 26 with the seal 25 can also move slightly relative to the outer mount 13.

3, 7, and 9 of the drawing, an annular space 30 is left between the screw part 16 with stepped head 16 a and the inner socket 14, which connects the inner pressure chamber 20 and the outer pressure chamber 22 to one another. 4 of the drawing, an annular space 31 is left between the inner socket 15 and the guide ring 26, through which the inner pressure chamber 21 and the outer pressure chamber 23 are connected to one another. Compressed air can pass via channels 32 and 33 to the threaded bores 18 and 19 of the pressure plate 11 and from there through a central blind hole 34 of the screw part 16 or a central blind hole 35 of the screw part 17 via radial bores 36 of the screw part 16 or radial bores 37 of the screw part 17 flow into the inner pressure chamber 20 or 21. From there, the compressed air can reach the outer pressure chamber 22 or 23 via the annular space 20 or 31 and press the press belt 10 there against the workpiece.

3, 7, 8 and 9 of the drawing, the pressure in the inner pressure chamber 20 causes the inner socket 14 with the seal 24 to be pressed against the press belt 10. The contact pressure depends on the pressure and the pressure exerted on the press belt 10 parallel surface of the inner socket 14 within the pressure chamber 20. This force is counteracted by a force which is dependent on the pressure in the outer pressure chamber 22 and the surface of the inner socket 14 which is acted upon by this pressure. The pressure in the outer pressure chamber 22 causes the press belt 10 to be pressed against the workpiece.

If, during operation, compressed air escapes from the outer pressure chamber 22 through a gap between the seal 24 and the press belt 10, then compressed air can flow from the inner pressure chamber 20 through the annular space 30 with a certain throttling effect. The air pressure in the outer pressure chamber 22 is then somewhat less than the pressure in the inner pressure chamber 20. If an undesired escape of compressed air from the outer pressure chamber 22 occurs during work, the pressure difference between the inner space 30 increases due to the throttling action of the annular space 30 Pressure chamber 20 and the outer pressure chamber 22, so that the resulting from the pressure forces of the inner pressure chamber 20 and the outer pressure chamber 22, the inner socket 14 with the seal 24 perpendicular to the pressure belt 10 pressing force.

Accordingly, according to FIG. 4 of the drawing, the pressure in the inner pressure chamber 21 causes the guide ring 26 with the seal 25 to be pressed against the press belt 10. The contact pressure depends on the pressure and the end face of the guide ring 26 which is parallel to the press belt 10 and which is within the inner pressure chamber 21 is located. This force is counteracted by a force which is dependent on the pressure in the outer pressure chamber 23 and the end face of the guide ring 26 which is acted upon by this pressure within the outer pressure chamber 23. The pressure in the outer pressure chamber 23 causes the press belt 10 to be pressed against the workpiece.

If, during operation, compressed air escapes from the outer pressure chamber 23 through a gap between the seal 25 and the press belt 10, then compressed air can flow from the inner pressure chamber 21 through the annular space 31 with a certain throttling effect. The air pressure in the outer pressure chamber 23 is then slightly less than the pressure in the inner pressure chamber 21. Thus, if an undesired escape of compressed air from the outer pressure chamber 23 occurs during work, the pressure difference between the inner space increases due to the throttling action of the annular space 31 Pressure chamber 21 and outer pressure chamber 22, so that force resulting from the pressure forces of these chambers, the guide ring 26 with the seal 25 perpendicular to the press belt 10 is greater.

So that in any case the force with which the inner socket 14 or the guide ring 26 is pressed against the press belt is greater than the force with which this socket or this guide ring is pressed away from the press belt 10 is in the inner pressure chamber 20 or 21, a helical compression spring 38 or 39 is used, which is supported at one end on the outer socket 12 or 13 and at the other end on the inner socket 14 or the guide ring 26. 3, 6, 7 and 9 of the drawing this helical compression spring 38 is conical, while the helical compression spring 39 according to FIG. 4 of the drawing is cylindrical.

However, since the throttling effect through the annular space 30 is often insufficient and pressure medium escapes undesirably, according to the invention, an additional shut-off device in the form of an O-shaped, preferably elastic sealing ring 40 is activated between the head 16a and the surface 14a on the press belt side an approach of the press belt side surface 14a with respect to the stepped head 16a closes the annular space 30, so that the pressure effect from the inner pressure chamber 20 on the inner socket 14 increases (see FIGS. 7 and 8).

Such a simple shut-off device allows the supply of the pressure medium from the inner chamber 20 into the outer chamber 22 to be controlled directly by the workpiece passing through, namely its outer contours.

If a workpiece runs in, it presses with its edges against the press belt 10 and lifts it on a surface which corresponds to the surface of the workpiece passing through. This raises all inner sockets 14 of the small pressure devices (pressure chambers) lying in the area of the edges and the surface of the workpiece passing through, so that the distance between the press belt side surface 14a and the stepped, fixed head 16a increases and thus the annular space 30 between the inner ones and outer chamber 20, 22 opens (Fig. 8). Thus pressure medium, which now flows into the outer pressure chamber 22, presses the press belt 10 against the workpiece that is passing through. After the passage, the rear edges of the workpiece release the inner socket 14 so that it is lowered and the annular space 30 is closed again by the sealing ring 40. The outer pressure chamber 22 is depressurized and thus also the press belt 10, which is not pressed into the free space (without a workpiece). Pressure medium can then not escape in a disadvantageous manner (Fig. 7).

In a modified embodiment according to FIGS. 9 and 10, the holding part (screw part) 16 shows, in addition to the bores 36 for supplying the pressure medium into the inner pressure chamber 20, further bores 41 which open and close, depending on the height setting of the inner frame 14, which is directly controlled in its position by the workpiece passing through.

If a workpiece runs in, the inner socket 14 lifts through the workpiece edge and releases the lower bores 41, so that pressure medium can also flow into the outer pressure chamber 22 and there, as in the exemplary embodiment according to FIG. 8, the press belt against presses the workpiece through. With the passage of the rear edge of the workpiece, the inner socket 14 lowers and thus closes the bores 41. For this purpose, the inner socket 14 can include the holding part 16 with a snug fit. If a small gap between the outer wall of the holding part 16 and the inner socket 14 cannot be eliminated in practice, it is expedient and preferred to insert a sealing ring 42 in this gap in order to prevent an unintentional inflow of pressure medium from the inner chamber 20 in to avoid the outer chamber 22.

Another advantage of the invention can be seen in the design of the screw part 16, 17, the bores 34, 35 of which are formed as blind holes, of which the radial bores 36, 37 open into the inner pressure chamber 20, 21. As a result, the compressed air initially builds up in the inner pressure chamber 20, 21 and moves the inner socket 14, 15 with seal 24, 25 onto the press belt 10 and already seals the outer pressure chamber 22, 23. Only after passing the annular space 30, 31 does the compressed air build up in the already sealed outer pressure chamber 22, 23 with a delay.

Claims (11)

1. Device for exerting surface pressure on advancing workpieces, comprising at least one endless pressing belt (10) which is capable of being pressed against the workpiece on the inside of the pressing belt by a pressure medium within series-arranged pressure chamber units provided with sealing strips (24, 25), said units being disposed on the active pressing surface of the pressing belt and being open towards the pressing belt, characterised by a plurality of such small pressure chamber units which are also disposed on the active pressing surface of the pressing belt transversely to the flow direction and are made openable and closable in order to adapt to the width of the workpiece passing therethrough, each of said units having the basic form of a round body with a circular surface area and being divided into two pressure chambers by an outer frame (12, 13) secured to a common pressure plate (11) and an inner frame (14, 15) which lies concentric with said outer frame and is displaceable vertically to the pressing belt (10), which pressure chambers, when viewed axially, are disposed one behind the other and represent an inner pressure chamber (20, 21) and an outer pressure chamber (22, 23), and wherein a spacing is maintained between the outer frame (12,13) and the inner frame (14,15), which spacing is bridged by a resilient sealing ring (28, 29).

2. Device according to claim 1, characterised in that the outer frame (12, 13) is secured to the pressure plate (11) by means of a screw member (16, 17) which lies concentric with said outer frame and is screw-connectable into a tapped bore (18,19) in the pressure plate (11), and the screw member (16,17) has a central blind bore (34, 35) extending from the side of the pressure plate (11) and a plurality of radial bores (36, 37) which connect the central bore (34, 35) to the inner pressure chamber (20, 21).

3. Device according to claims 1 and 2, characterised in that each pressure chamber is divided into an inner pressure chamber (20, 21) adjacent the pressure plate (11) and an outer pressure chamber (22, 23) abutting against the pressing belt (10), and the inner pressure chamber (20) and the outer pressure chamber (21) are interconnected by means of an annular chamber (30) defined between the inner frame (14) and the screw member (16) (Fig. 3).

4. Device according to claims 1 to 3, characterised in that the seal (24) is secured to the inner frame (14) and is displaceable with said inner frame (Figs. 3 and 5-10), and the seal (25) is secured to a guide ring (26) disposed between the outer frame (13) and the inner frame (15) and is displaceable with said guide ring (Fig. 4).

5. Device according to claims 1 to 4, characterised in that the inner pressure chamber (21) and the outer pressure chamber (23) are interconnected by means of an annular chamber (31) defined between the inner frame (15) and the guide ring (26) (Fig. 4).

6. Device according to claims 1 to 5, characterised in that a helical compression spring (38, 39) is disposed between the inner frame (14, 15) and the outer frame (12, 13).

7. Device according to claims 1 to 6, characterised in that a shut-off device (40, 42), which occasionally cuts the supply of pressure medium from the inner pressure chamber (20) to the outer pressure chamber (22), is provided between each respective group of two pressure chambers (20, 22).

8. Device according to claims 1 to 7, characterised in that an 0-ring (40), serving as a shut-off device, is inserted between the surface (14a) of the inner frame (14) and a stepped head (16a) of the retaining member (16).

9. Device according to claims 1 to 8, characterised in that a transverse bore (41) or a plurality thereof is or are provided in the retaining member (16) between the bore (36) and the stepped head (16a) of the retaining member (16), wherein the spacing between the transverse bore (41) and the bore (36) is somewhat larger than the thickness of the central wall of the inner frame (14).

10. Device according to claims 1 to 9, characterised in that an O-ring (42) is inserted in the annular chamber (30) between the retaining member (16) and the inner frame (14).

11. Device according to claims 1 to 10, characterised in that the retaining member (16) is in the form of a screw, the head (16a) of which protrudes into the outer pressure chamber (22).

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