EP1657210B2 - Crane with fibre cable - Google Patents

Abstract

The lifting device, in particular, in the form of a crane has one or more ropes for lifting loads or anchoring a jib, with at least a part of ropes being fiber ropes.

Description

The invention relates to a crane, with one or more cables, for example for lifting loads or for adjusting or unclamping a boom according to the preamble of claim 1. Hoists are known in numerous different embodiments. Especially in the field of cranes there is a variety of design variants that have to meet a wide variety of requirements.

The ropes used in known hoists consist of a variety of steel wires, which are processed into strands. Usually, the ropes consist of a rope core, which consists of strands stranded together. The outer strands are beaten around the rope core. The steel cables used today are known in various designs. They are usually wound on cable drums, whereby due to the ability of steel cables to absorb shear forces, a multi-layer winding is possible and common.

However, a major disadvantage of steel cables used today is their weight, which, depending on the cable design with a rope diameter of 22 mm, for. about 2.1 kg / m and at a rope diameter of 30 mm, e.g. about 4.5 kg / m. The relatively high rope weight naturally reduces the payload of the hoist or increases the total weight of the hoist or the transport weight of mobile hoists, such as e.g. mobile cranes.

Out EP 1 331 191 a crane according to the preamble of claim 1 is known. More cranes are from the GB 2009077A and the DE 19854321 A known. Fiber ropes for cranes are out of the DE 2455273 A1 known.

The present invention is therefore the object of developing a hoist to the effect that its weight is reduced or that its payload is increased.

This object is achieved by a hoist with the features of claim 1. Thereafter, it is envisaged that the ropes are at least partially fiber ropes. This applies to hoisting ropes for lifting the load or ropes for adjusting a boom. The rope weight plays an essential role in the hoists. It leads to an increase in the payload or to a reduction in the total weight or transport weight of mobile cranes.

The fiber rope is preferably an aramid rope, i. around a rope has the aramid fibers or is composed of these. The material aramid is aromatic polyamide with high strength and low weight. The weight of an aramid rope at comparable breaking force is only about 45% of the weight of a Stahiseiles. Further advantages are a small D / d ratio, i. It can be small pulley diameter and thus smaller drives realize, as well as the long service life with respect. The flexural strength, which is higher by a factor of 60 than that of steel cables. Another advantage is the high coefficient of friction of 0.3 to 0.6, which makes the ropes particularly suitable for a traction sheave drive. Furthermore, the low noise of the ropes can be mentioned.

In today known Aramidseilen a multi-layer winding is problematic insofar as they do not transmit transverse forces in contrast to steel cables and show a large degree of ovalization. It follows that it is advantageous if only drums are used with single-layer winding, however, associated with the disadvantage that only small hook heights can be realized. Basically, the invention is not limited to single-layer windings. If fiber ropes with a low degree of ovalization are used, a conventional multi-layer winding in the area of the rope drive is also conceivable for these, as in the case of steel ropes.

According to the invention, a cable drive and a storage drum for winding the rope is provided. The required cable traction is applied by the cable drive. The cable drive may e.g. be designed as a capstan drive or as a traction sheave drive. The pulling force required to lift the load or to move a boom is applied by the traction sheave or by the spreader head. The storage drum serves to accommodate the unneeded rope length, in which case a multi-layer winding is conceivable if the tensile force for winding the rope on the storage drum is selected to be correspondingly low.

The cable drive may be e.g. to act a lifting drive or even a boom adjustment. Other applications are possible.

The arrangement of the storage drum is carried out according to claim 1. The cable feed can be fed by deflections the respective traction sheaves or the spill head. The hoist is a tower crane, in which the storage drum is arranged on the counter-jib. The storage drum can be placed at a large distance to the pivot point of the counter-jib. The cable drive, ie preferably the spill drive or the traction sheave drive can be arranged for example on the spire. Thus, a sufficient distance between the two positions drive and drum would be available to run a drum with the necessary storage option.

According to the invention, the storage drum is connected so that it always exerts a tensile force and thus the rope already with bias on the respective drive unit (for example traction sheave drive, spill drive) enters. In such an embodiment of the invention, there is the advantage that the bias or the cable tensile force can be adjusted so that the storage drum can be wound in multiple layers. It is conceivable, e.g. a cable traction of a few hundred kilograms. The winding of the storage drum is preferably carried out by means of a winding device.

In a further embodiment of the invention, it is provided that the cable guide is such that the rope has a 2-fold, 4-fold or more than 4-fold reeving (x-fold reeving). Especially with mobile cranes are 6-, 8-, 10-fold, etc. Shearing is not a special feature. The cable guide has a significant influence on the necessary hook weight and on the payload, as will be explained in more detail below.

Today known Aramidseile have the property of a turning angle in the range of 40 ° to 120 ° at full traction. In order to prevent screwing the hook bottle, a swirl compensator can be provided in a further embodiment of the invention, which opposes the rotation angle behavior of the rope counter rotation. The swirl compensator can be electrically operated and used manually or automatically. It serves to counteract the rotation angle behavior of the rope. If means for torque detection are available, it would be possible to counter-rotate automatically via this swirl compensator. Preferably, the swirl compensator is provided in the region of the rope endpoint.

In tower cranes is essential that the rope is always moved from the hoist drum from the range of counterweight almost forward. This means that with large hook heights, several tons of rope are transported by the counterweight to the position of the load. Relative to the load torque, this means a counterweight decrease and a self-weight increase. A smaller dead weight of the rope would have a positive effect on the loads occurring through the steel construction spire and slewing ring, as this plus / minus load, be it in the load torque or discharge of the moment becomes much smaller and thereby also influence the tower and the slewing ring of the Cranes or substructure and corner pressures has.

Figur 1:

Darstellung zur Ermittlung des Lasthakengewichtes in Abhängigkeit verschiedener Parameter bei einem Turmdrehkran,

Figur 2, 3:

Darstellung zur Verdeutlichung der Steigerung der Nutzlast anhand zweier unterschiedlicher Turmdrehkrane.

Further details and advantages of the invention will be explained in more detail with reference to an embodiment shown in the drawing.

FIG. 1:

Representation for determining the load hook weight as a function of various parameters in a tower crane,

2, 3:

Representation to illustrate the increase in payload using two different tower cranes.

FIG. 1 shows in a schematic representation of the upper portion of a tower crane with main boom 10 and counter-jib 20. As from the legend to FIG. 1 can be seen, the reference character g denotes the rope weight per meter of rope length (kg / m), f the rope sag, I the main boom length and the reference H the cable traction. The load hook weight LAH can be determined with a two-strand cable guide via the relation LAH = 2 * H. The load hook weight is necessary to limit the rope slack on the boom and to ensure a good Seilspulung without load.

The rope weight g and the boom length I are given. Likewise, the maximum rope sag f is fixed, which is 5 to 6 m in the illustrated embodiment. By means of in FIG. 1 given relationship, the cable pull force and thus the hook weight can be determined. Since the cable traction and thus the hook weight is directly proportional to the rope weight, can be exercised by changing the weight of the rope a significant impact on the load hook weight and thus on the available payload, as exemplified in the Figures 2 and 3 evident.

FIG. 1 further shows the storage drum 30, which is arranged in the spaced from the articulation point of the counter-jib 20 region of the counter jib 20, and by the reference numeral 40, the cable drive, which can be configured for example as a capstan drive or as a traction sheave drive.

FIG. 2 shows the load curves for a tower crane when using a steel rope (St) and when using an aramid rope (F) as a hoist rope. The values given are for a 2-strand reeving with a maximum load of 12 t (steel rope). The comparison involved the use of a steel rope weighing 2.1 kg / m and an aramid rope weighing 0.945 kg / m.

As from the table in FIG. 2 As can be seen, the use of the fiber rope already results in a reduction of the load hook weight by 330 kg. With a rope length of 60 m (single), ie with 2-fold reeving with a total length of 120 m, this results in a total weight (load hook weight and rope weight) of 383 kg. Compared with the total weight when using a steel cable results in a reduction of 470 kg. It follows that the peak load can be increased by approximately 18.8% when using an aramid rope compared to when using a steel cable (2.5 t). The maximum payload is increased by about 4% due to the reduced weight of the rope and the load hook.

This significant increase in peak load falls at higher hook heights and more than 2-fold reeving even clearer.

Based on the above-mentioned data for the steel cable and the aramid rope, a hook height of 200 m already results in a peak load increase of 41% and an increase in the maximum load capacity of approx. 7%.

When using a steel cable with a maximum load of 20 t (rope diameter 30 mm, cable weight 4.52 kg / m) the following results in comparison to an aramid rope with a rope weight of 2.03 kg / m: For a standard hook height of 60 m and 2 -fold reeving results in a weight saving (load hook and rope) of 850 kg when using the aramid rope, whereby the load at the top of 5.4 t when using a steel cable to 6.25 t, ie increase by about 16%. The maximum load can be increased by approx. 4.3%. With a hook height of 200 m, an increase of the peak load torque by approx. 37.4% and the maximum load by approx. 8.2% can be achieved.

The effect above affects the bigger the crane is. In cranes that work with 4-fold reeving and also go over greater heights, results in the above example (hook height 60 m) with a diameter of the steel cable of 30 mm and a cable weight of 4.52 kg / m, a peak load increase of about 47% and an increase in the maximum load capacity by about 4.25%.

Out FIG. 3 The values for a hook height of 200 m and 4-strand design for a steel cable with a cable weight of 4.52 kg / m and for an aramid rope with a cable weight of 2.03 kg / m. How out FIG. 3 As can be seen, the maximum load is increased by approximately 8% and the peak load torque by approximately 290%.

The examples mentioned show the considerable influence that the cable weight has on the load torque as a function of the lifting height. For cranes in the 20 t version, peak load increases of approx. 20% and with not too high lift heights of 200 m to almost 40% are possible according to the above examples with a free crane installation height of approx. 60 m. For large cranes with large loads, e.g. 40 t, which work in 4-strand operation, result in peak load increases at 60 m installation height of approx. 50% and at 200 m hook height up to 290%. In order to achieve such an increase in performance with today's customary steel cables, substantially larger, more powerful hoists, such as e.g. a 400 m crane instead of a 300 m crane can be used at a higher cost.

Claims (9)

1. A crane having one or more ropes, for example for the raising of loads or for the adjustment or guying of a jib, wherein at least some of the ropes are fibre ropes, characterised in that the crane has a rope drive and a storage drum for the winding up of the fibre rope, with the storage drum being connected such that a tensile force is always exerted onto the fibre rope so that the fibre rope runs onto the rope drive with pre-stress, with the crane being a tower crane and the storage drum being arranged at the counter-jib.
2. A crane in accordance with claim 1, characterised in that the fibre ropes are aramid ropes.
3. A crane in accordance with any one of the preceding claims, characterised in that the rope drive is made as a capstan drive or as a traction sheave drive.
4. A crane in accordance with any one of the preceding claims, characterised in that the rope drive is a lift drive or a jib adjustment drive.
5. A crane in accordance with any one of the preceding claims, characterised in that the rope drive is arranged in the region of the top of the tower.
6. A crane in accordance with any one of the preceding claims, characterised in that a winding apparatus is provided by means of which the storage drum can be wound up in multiple layers.
7. A crane in accordance with any one of the preceding claims, characterised in that the rope has two-fold, four-fold or more than four-fold reeving.
8. A crane in accordance with any one of the preceding claims, characterised in that a twist compensator is provided which sets a counter-rotation against the angle of rotation behaviour of the rope.
9. A crane in accordance with claim 8, characterised in that the twist compensator is operated electrically.

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