Patent Application
20150083684
The present patent document claims the benefit of priority to German Patent Application No. 202013008487.1, filed Sep. 24, 2013, and entitled “ROPE GUIDE FOR A CRANE,” the entire contents of each of which are incorporated herein by reference.
The invention relates to a rope guide for a crane, in particular a rope guide for a telescopic crane. It may be used for all crane ropes which extend along the crane boom, for example the hoist rope of the crane.
Generally speaking, such a hoist rope of the crane is guided across the top face of the crane boom from the hoist to the head reel. In this respect, precautions need to be taken to prevent the rope from brushing against the top face of the crane and different variations of guiding elements are used for this purpose in the prior art. Especially if the telescopic boom deforms under load, these guiding elements help to allow the rope to be freely guided without coming into contact with the boom's top face.
In the case of one known embodiment, the guiding elements have ball bearing mounted rope rollers across which the hoist rope can run. Such a design known from the prior art is illustrated in
Another option is to use rope rollers on the spacers in the case of larger cranes due to the large height requirement.
Another option would be to use plastic blocks, in which case such a plastic block would be disposed on the end of each and every telescope part, which would then enable the rope to conform to the elastic deformation of the boom. The disadvantage of this resides in the local high pressure intensity caused by the rigid connection and in the high degree of wear.
The objective of this invention is to propose a rope guide for a crane which overcomes at least one of the above-mentioned problems known from the prior art. In particular, the intention is to optimize the rope guide by means of the spacers. This objective is achieved by the invention on the basis of a rope guide for a crane as defined in claim 1. The dependent claims define preferred embodiments of this invention.
Based on a rope guide for a crane as proposed by this invention, in particular a rope guide for a telescopic crane, at least one guiding element is provided for a rope which extends from a boom head along a boom or telescopic boom of the crane. At least one of the guiding elements comprises a spacer which has a concave form on its surface facing the rope, substantially complementing the rope contour.
In other words, this invention proposes a spacer with a friction-type bearing for the rope and the surface across which the rope glides or slides has a contour which is essentially adapted to the external contour of the rope. In principle, there need not be an exact match of contours but adapting to the round form will always increase the contact surface or sliding surface and thus will significantly reduce the pressure intensity which occurs.
The reduced pressure intensity between the rope and its sliding surface achieved by the invention enables a reduction in pressure intensity of up to 80% or even 90% to be achieved if an appropriate contour is selected. This results in a number of advantages and one of them is the significantly reduced damage to the rope, which is significantly less than the rope damage which occurs in the case of multi-layered spooling on the hoist. Accordingly, rope damage on the hoist remains the crucial feature in terms of structural design for addressing this wear factor and corresponding calculations need to be made an remain reliable. Other advantages of reduced load on the rope are an essentially longer service life of both the rope and the spacers or guiding elements and the fact that, due to the optimized surface structure, a sufficiently long service life can be achieved with very little material. As anti-friction elements, the guiding elements or spacers are based on a very simple construction and are thus virtually substantially maintenance-free and require only a minimal height for fitting. The latter advantage offers room for optimizing the boom and in turn options for optimizing the ultimate load.
Based on one embodiment of the invention, the spacer surface (rope-sliding surface) has at least one groove in the rope direction. The complementary form mentioned above means adapting the rope external form and concave inner form to a greater or lesser degree, i.e. from large radii on the sliding surface down to relatively small radii, which are highly adapted to the rope radius. In this respect, optimization will depend on the respective situation and various appropriate adaptations are possible. The embodiment incorporating a groove in the rope direction demonstrates that it is not necessary for the entire spacer to have a concave form on its sliding surface for the purpose of the invention—instead, it may be rounded in such a way across only a certain region of its width transversely to the rope direction and may be of some other appropriate design otherwise. As stated, at least one groove may be provided.
However, another option is for the spacer surface to be designed so that it has several adjacently lying grooves in the rope direction. These are of particular advantage when operating in 2-hook mode for example, because the two hoist ropes can then find a space in individual adjacently lying grooves. Similarly, an individual hoist rope may also sit in another groove with this embodiment, depending on the load situation or curvature of the boom, thereby ensuring effective guiding in every situation.
One option is to provide raised projections between the grooves with side walls sloping down towards the grooves, as a result of which the guided rope always slides down into one of the grooves where it will also be stabilized from the sides accordingly. If opting for a design where the projections are round or rounded on their top face, load or wear on the rope when “switching” groove will be reduced or eliminated.
Based on one embodiment, the spacers have a rope support, which is outwardly cambered in an arcuate shape in the direction in which the rope runs or, in other words, has a convex form in this direction. This ensures that the rope does not have to run over the front edge or rear edge of the rope support even in the event of pronounced deformation of the telescopic boom, which would result in increased pressure intensity and greater wear.
The rope-sliding surface or, in other words, the rope support of the spacer, may be provided with a coating, the hardness of which is higher than that of the rope. Another or additional option is for the rope support or even the entire spacer to be made entirely from a material with a higher hardness than that of the rope. In both situations, the coating or the rope support material is resistant to abrasion with respect to the rope friction or rope material. Naturally, the advantage of this is the fact that wear on the spacer at the rope-sliding surface is low, which results in long periods between maintenance and replacement as well as reliable operation.
The coating or the rope support material used for embodiments of this invention are selected from at least one of the following materials or incorporates one of the following materials:
sheet metal, in particular hardened sheet metal,
Hardox ® Extreme, made by SSAB AB of Klarabergsviadukten 70, D6, 10121 Stockholm, SE, having the following properties:
thin films with
aluminium oxide,
zirconium oxide.
Based on one embodiment, the spacers are mounted on the boom so that they can move or are fixed. They may be mounted on or secured to the boom so as to be flexible and/or elastic and/or capable of rebounding into their initial position, and the mounting or fixing of the spacers on the boom may be such that the angle of the spacers relative to the longitudinal direction of the telescopic boom can be adjusted. Another option is to mount or secure the spacers on the boom via a mechanical, rigid mounting or fixing element or mechanism and impart flexibility via an elastic material inserted between the fixing element and spacer. Alternatively, the ability of the spacer to move and/or for its angle to be adjusted may also be achieved on the basis of the intrinsic elasticity of its material. Yet another option is for the spacers to be mounted on or secured to the boom via of a fixing element or mechanism that is flexible or can be moved in order to adjust the angle, in particular by way of an articulated fixing mechanism or a fixing mechanism incorporating a joint.
All of these embodiments with the displaceable spacers make it possible for guiding of the rope or deflection of the rope by the spacers to be adapted to different loads of the boom. This enables different degrees of deformation of the boom as a whole to be compensated, i.e. the rope guide is able to “conform” to these deformations at a distance from the boom. Assembly is also made easier.
In principle, it is possible to mount a rope guide for a crane of the type proposed by this invention on a crane with a simple, non-telescopic boom. In this instance, it would be of practical advantage to secure the guiding element or the spacer on the boom more centrally at the top so that the rope is able to conform to deformations at a distance from the boom surface.
In some of the different variants, however, the boom is a telescopic boom and guiding elements or spacers are disposed on each or several or every second, third or fourth telescope part, in particular at its front end, thereby enabling the rope guide to be optimized to suit the respective application. Naturally, depending on which embodiment is required and the requirements of the specific application, spacers may be provided at all possible regular distances and irregular distances on the telescopic boom.
The invention will be described in more detail below with reference to embodiments and with the aid of the appended drawings. Of the drawings:
At this stage, an explanation of the concepts and definitions used in the context of the description of this invention will be given. The invention is defined as being a rope guide for a crane in order to introduce the design of its guiding elements and spacers into the appropriate technical field. However, their characterizing, inventive features may be implemented as broadly as possible and in almost all embodiments incorporating the design of the guiding elements and spacers which might constitute the subject matter of the invention as such in this sense. In this disclosure, “guiding elements” should be understood as meaning specifically the “spacers” in many cases—however, the guiding elements could in principle also be additional components or have other features or properties which do not have any direct bearing on the spacer function. For example, the expression “guiding element” might also include jib fixing means for the spacers. Accordingly, “guiding element” may also be construed as a generic term for “spacer”.
Although
To provide more detail, one of the spacers 3A is illustrated in
An upwardly extending bearing plate 13 is mounted on the section A by way of a screw fixing 14. Placed around this bearing plate 13 on either side are layers 12 of an elastomer material, onto which the spacer 3A with two bottom webs 11 is positioned so that the two webs 11 grip tightly around the elastomer layers 12 from outside. Adjoining the two webs 11 at the top is the rope support 10 of the spacer 3A, and a rope 6 is illustrated lying on it.
The elastomer material 12 used between the webs 11 and the bearing plate 13 ensures that the spacer 3A is able to move elastically in the direction indicated by the two small arrows and its angle can thus be adjusted to enable it to conform to different deformations resulting from different loads. As explained above, this angular adjustability can also be achieved by various other means, for example by articulated bearings or on the basis of the intrinsic elasticity of the components of the spacer itself or that of its fixing elements.
One property of the rope support may be seen in
Whereas the rope support 10 illustrated in
The concave design (transversely to the rope direction) of the rope-sliding surface may be seen in
With the aid of the angular adjustability, this state is also maintained in the event of different and pronounced boom deformations. Damage to the rope remains well below the damage incurred with multi-layered spooling, 2-hook operation is made possible, optimum use can be made of the design height and the service life can be increased with less maintenance.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202013008487.1 | Sep 2013 | DE | national |
