EP0088347B2 - Apparatus for keeping the tension of metal strips at a constant level - Google Patents

Abstract

Strip processing lines require tension or back tension to be applied to the strip, as the case may be. These requirements are best met by the proposed chain bridle. The recoiling of adjacent slit strips on a tension reel will result in varying rewinding speeds and tensions due to the different thickness of the individual strands. Thick strands will be rewound too tight and thin strip too loose. Therefore, the chain bridle is installed before the tension reel to keep the tension of the various strands or a wide strip at a constant value. The strip (1) is clamped between two circulating chain systems (4a,4b), one arranged below and the other above the strip passline. One chain system (4b) is fixed, the other one (4a) is adjustable. The chain segments (4) of the chain systems (4a,4b) are provided with a covering and are moved parallel to the strip (1) through support rolls (5) and guide gibs (6a) with entry and exit guide curves (6) with the latter ensuring an adequate clamping pressure of the relevant opposite chain segments (4). The segment covering (7) may consist of an elastic coating (11) provided with additional shapes or profiled surfaces (12).

Description

The invention relates to a device for pulling or braking metal strips, in particular narrow strips to be wound together, with band-wise separate braking action, preferably in band lines, between two sprockets that are endlessly rotating and can be pressed against one another, and are articulated from one another, in pairs above and below the metal band arranged links existing, the metal band between clamping chain systems.

Metal strip is preferably moved in strip treatment plants with drivers or pull and brake roller systems. The necessary strip tension is generated in such a plant in addition to drivers and reels, especially with pull and brake roller systems. The rollers are driven and more or less wrapped around the belt. The strip hoists can only be set up or taken down from roll to roll within very specific limits. The belt deflections require additional drive power and are undesirable for metallurgical and technological reasons. In practice, the roller diameters are chosen so that parts of the belt are plastically deformed even with small belt thicknesses. These disadvantages are of particular importance for thicker strips, for stainless steel strips, for special qualities such as silicon strip and surface-sensitive strips.

A device of the type mentioned has become known from AT-A-295 974. The difficulties encountered when winding sheet metal strips, in particular sheet metal strips cut into longitudinal strips, onto a reel core are eliminated there by combining a friction brake with a brake generator. The inclusion of a friction brake in the braking device should make it possible to compensate for the speed differences between the individual strip strips by means of sliding friction, i.e. to apply the braking force, the force of the brake generator is supported by the frictional force caused by the sliding friction of the friction brake. The sliding friction occurs when it is possible to slide the brake bands, which are not driven but are carried along by the continuous sheet metal strip, relative to the sheet metal strip. This known braking device therefore presupposes the generation and exploitation of relative movements as functionally decisive. Due to the relative movements, damage to the surface of the sheet metal strip cannot be prevented. In the clamping or driving area of the sheet metal strip, pressure rollers acting on their plate members are arranged to press against each other. These pressure rollers are based on the principle of a stringing together of drivers known in strip treatment plants and used for moving metal strip; apart from the distribution of the loads on a number of pressure points corresponding to the number of driver rollers arranged opposite one another, this pressure roller arrangement does not differ from the known drivers. Thus, initially there is only a line contact, which is formed by further squeezing when pressed onto a surface. These flats lead to different effective diameters and thus relative movements on the metal strip surface. Due to the driver function of the pressure rollers, the brake bands also buckle. This is particularly the case when the transition between two plate members of the brake bands reaches the area of the pressure rollers.

From GB-A 2 072 152 a device is known in which a metal band is clamped between two driven, endlessly rotating friction systems. For this purpose, two belts arranged opposite one another in a machine frame and deflected by guide and drive rollers are provided, which hold the metal strip between them. For tensioning, the upper belt is set against the opposite, lower belt by means of a hydraulic cylinder. The hydraulic cylinder engages a support frame which receives the drive rollers and is resiliently supported by springs and connected to a pressure plate which lies against the belt from above; the pressure plate supporting the opposite belt, however, is not adjustable. With this known device, however, no tensile forces can be applied, since they would have to be introduced where a particularly low coefficient of friction is to be provided for the purpose of the desired good sliding along the pressure plate.

The disadvantages listed here are eliminated by the chain pulling machine described below. Further advantages of this device are that the advance is gentle on the surface, since there are no relative movements and the specific load can be kept very low, the space requirement is lower, especially when there is a large train difference and with larger strip thicknesses, and the cost calculations are also significantly cheaper.

The chain pulling and braking device can be used in particular as a brake scaffold in splitting systems.

When winding narrow-band slit strips onto a reel, due to deviations in thickness, which can be attributed to the geometry of a rolled broad strip, the strip strips wound next to one another on the reel have different winding diameters and therefore less different winding speeds and tensions. The thick tape strips are therefore too tight and the thin tape strips are wound too loosely.

In order to achieve uniform narrow bundles, restraint or braking devices are therefore already known, which compensate for different strip tension when winding narrow strips even without direct action on the surfaces of the split strips by means of band brakes. A known retaining device (DE-PS 1804 178) consists of several rings which are rotatably arranged under friction on a shaft upstream of the reel. The braking torque can be adjusted to a maximum belt tension by means of an axially supplied pressure medium, the braking torque being transmitted to the flanks of the ring hubs by means of friction disks that are inserted between the rings. If higher stresses occur, the corresponding rings perform compensating rotary movements relative to the shaft and to the other rings. The design of these restraint devices with a large number of brake disks to be machined precisely and braking surfaces provided on the ring hubs is very complex. In addition, it is disadvantageous that a device is required which has to apply the preference in order to subsequently be able to reinforce the train.

The invention has for its object to avoid the aforementioned disadvantages and to provide a simple and reliable device for keeping the tension constant for slit strips and unsplit strips, without the need for an additional preferred device. When pulling wide strip material out of a tension-free strip length, whereby the strip tends to run sideways, the elaborate control driver can be omitted, since the rectangular entry of the strip is achieved by the twisting movement of the chain pulling and braking device.

This object is achieved in that two adjacent links are connected via a common hinge axis and each hinge axis is supported in the driving area via rollers or sliding surfaces on guide rails for transferring the pressure. According to further refinements of the invention, it is proposed that the links have coatings, preferably an elastic covering, which can advantageously be equipped with a profile. By means of the coatings, the elasticity of which can be influenced by the thickness, the profiling and the degree of hardness, a high coefficient of friction can be achieved between the links and the metal strip; on the other hand, due to the support of the links via rollers or sliding surfaces, there is a low coefficient of friction with the guide strips.

This makes it possible to hold back the tape without relative movement between the tape and the contact surface of the covering and to keep the surface free of all changes in the case of sensitive tapes. The support rollers are fed to the support area via a run-up curve, so that the respective chain segment is smoothly taken over.

The chain brake device is preferably adjusted in slit systems according to the lowest strip speed. The strip strips with the faster strip speeds have an advance in the contact area of the chain brake device. The associated different lengths of the slit band are compensated for by the elasticity of the covering, which is initially compressed and allows resilience in the area of the respective advance. The specific tension in the strip cross-section changes only insignificantly, since the pressure forces can be distributed over a relatively large area. These relationships are shown schematically in FIGS. 5-5b, the strip speed = peripheral speed according to FIG. 5; according to FIG. 5a the strip speed is> peripheral speed and according to FIG. 5b the strip speed is »peripheral speed. It is also an important effect that the design of the start-up curves enables a preload to be applied to the covering, which is expediently designed as a stud.

With the pulling and retention device created in this way, the narrow-band slit strips can be wound up with uniform tension regardless of thickness differences. The pulling or braking forces can be regulated continuously over a wide range using the contact pressure of the chain systems. The transferable forces can be significantly increased by using additional chain wheels or support structures within the chain systems.

The chain pulling and braking device can still be used wherever the so-called S-roller units are used in belt treatment lines. A particular advantage is that the required belt tension can be brought up to the maximum belt tension required in practice, even with preference = 0.

Stretch-bending straightening units are provided with up to 5 S-rolls in front of and behind the bending stand so that the necessary strip tension can be applied. It is expedient to equip each individual S-roll with egg ₁ em separate GS drive bzw.- in a mechanical coupling with a GS-Ausgleichsanvieb. This is necessary because, due to the manufacturing tolerances and the uneven wear of the S-roll coatings, ₃ relative speeds are avoided have to. This leads to a considerable expenditure of mechanical and electrical equipment as well as a large space requirement. When using the chain pulling and braking device proposed by me, only one scaffold in front of and behind the stretch-bending straightening unit is necessary. Only two GS drives are required.

In modern strip treatment plants, it is expedient to arrange a strip center control unit in front of each S-roll unit so that the strip is fed to the S-roll unit in the center of the system. A special embodiment of the chain pulling and braking device provides that the rectangular entry of the belt into the device is achieved by means of a pivoting movement in the belt passage plane. This process can be automated.

If the chain pulling and braking device is arranged in front of the take-up reel, it is a special embodiment that the device is adjusted according to the continuously changing entry angle of the incoming strip. This arrangement has the advantage that the tape retraction is applied immediately before the take-up reel.

• Fig. 2 einer Kettenzieh- und Bremsvorrichtung mit den erfindungsgemässen Kettensystemen,
• Fig. 2 einen Schnitt entlang der Linie I-I der Fig. 1,
• Fig. 3 einen Schnitt entlang der Linie II-II der Fig. 1,
• Fig. 4 einen Teilabschnitt der Ketten mit Beschichtung
• Fig. 4a einen Schnitt entlang der Linie IV-IV der Fig. 4 und
• Fig. 5, 5a, 5b eine schematische Darstellung der Fasern in der Beschichtung an verschiedenen Positionen.

In the drawings, an embodiment of a tensioning device according to the invention is shown and that: FIG. 1 shows the schematic representation of the side view and a section along the line III-III of FIG

• 2 a chain pulling and braking device with the chain systems according to the invention,
• 2 shows a section along the line II of FIG. 1,
• 3 shows a section along the line II-II of FIG. 1,
• Fig. 4 shows a portion of the chains with coating
• Fig. 4a is a section along the line IV-IV of Fig. 4 and
• 5, 5a, 5b a schematic representation of the fibers in the coating at different positions.

If the chain pulling and braking device is used in a gap line as a brake stand, the narrow belts would be fed from a splitting shear, not shown, via a loop storage device with a deflection roller and then through the chain brake device via a further deflection roller to the take-up reel. The actual chain brake device remains unchanged in all gap programs

The chain system is preferably operated by a direct current motor with a comb gear connected downstream. The braking torques are passed on via the shaft 2 to the chain wheels 3 and to the chain segments. The support rollers 5 transmit the torques once and support the segments 4 in the driving area via guide strips 6a with support curves 6 in the inlet and outlet and brace the belt 1 by chain segments 4 lying opposite each other over the segment coating 7, which as an elastic covering 11 with a profile 12 can be executed.

The lower chain system 4b is fixed, while the upper chain system 4a is adjustable. The contact forces are adjustable. The chains are pretensioned by means of cylinder 8, which displaces a guided bearing housing 9. The oscillating rotating brush 10 removes all possible contaminations and buildup on the contact surfaces.

A special application provides that the fixed chain system is designed as a rocker construction 13. This ensures that the chain pulling and braking device can be tilted to a certain angle in accordance with the incoming belt.

The control frame 14 has the task, if the band does not run at 90 ° on the segments 4, to turn the entire chain pulling and braking device in the band plane until the right-angled band entry is restored. Automatic control is state of the art.

Claims (7)

1. Apparatus for pulling or braking metal strips (1), especially narrow strips to be reeled jointly and with a separate braking action for each strip, preferably in strip lines, between two chain systems (4a,4b) which circulate endlessly around chain wheels, can be pressed against each other, consist of individual links connected to one another in an articulated manner and arranged in pairs opposite each other above and below the metal strip (1), and clamp the metal strip between them, characterised in that two adjacent links are in each case connected via a common hinge pin, and each hinge pin is supported in the driving region on guide bars (6,6a) via rollers (5) or sliding surfaces in order to transfer a pressing force.

2. Apparatus according to claim 1, characterised in that the links (4) have coverings (7).

3. Apparatus according to claim 1 or 2, characterised in that the links (4) receive an elastic facing (11).

4. Apparatus according to claim 3, charaterised in that the elastic facing (11) is provided with a profiling.

5. Apparatus according to claim 1, characterised in that the guide bar (6a) possesses inlet and outlet curves, and inclines (6).

6. Apparatus according to claims 1 to 5, characterised by an adjusting frame carrying the device.

7. Apparatus according to claim 1 to 5, characterised by a pivotably mounted structure carrying the device.

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