WO2020193676A1

WO2020193676A1 - Tensioning device, in particular belt ratchet

Info

Publication number: WO2020193676A1
Application number: PCT/EP2020/058470
Authority: WO
Inventors: Uwe Schöbel
Original assignee: Westdeutscher Drahtseil-Verkauf Dolezych Gmbh & Co. Kg
Priority date: 2019-03-26
Filing date: 2020-03-26
Publication date: 2020-10-01
Also published as: DE202019101719U1

Abstract

The invention relates to a tensioning device, in particular a belt ratchet, having a base frame (2), also having at least one winding shaft (3) rotatably mounted in the base frame (2), and having a handle (6) for driving the winding shaft (3), one or more tensioning means (1) for transmitting tension being connected to the base frame (2) and to the winding shaft (3), characterised in that tensioned functional elements (2, 4, 5) subjected to tension are produced from a different material compared to untensioned functional elements (3, 6).

Description

Tensioning device, especially belt ratchet

Description:

The invention relates to a tensioning device, in particular a belt ratchet, with a base frame, furthermore with at least one winding shaft rotatably mounted in the base frame, and with a handle for driving the winding shaft, one or more tensioning means being connected to the base frame and the winding shaft for tensile transmission.

Clamping devices of the structure described at the outset are typically used to secure loads or loads and, in particular, to delay such loads on transport surfaces in connection with the transport securing. For this purpose, the tensioning means is usually one or more belts, in particular plastic fabric belts. The general procedure here is that one end (the fixed end) of the clamping device is connected to the base frame, while a loose end of another clamping device or belt is usually looped around or into the winding shaft, so that by turning the winding shaft with the aid of the Handle the desired tensile stress in the tensioning device or the tension belt can be built up in order to achieve the desired load securing.

With the help of such tensioning devices and especially belt ratchets, tensioning forces of several 100 daN can be achieved. Nowadays clamping forces of over 1000 and even 2000 or 2500 daN are often required as a minimum. Such clamping forces must not only be absorbed by the flexible clamping means guided around the load to be secured, but also by the clamping device. In fact, such tensioning devices are generally actuated manually by an operator the handle for driving the winding shaft typically swings back and forth. In connection with a ratchet lock assigned to the winding shaft, the desired tensioning force can be generated in the tensioning means. This has basically proven itself, for which reference is made to the generic prior art according to DE 37 23 846 A1 or also according to DE 29 14 888 A1.

Due to the aforementioned clamping forces of several 100 daN, the known clamping devices are of massive construction and are largely made of steel and in particular high-strength steel. As a result, such tensioning devices and especially belt ratchets add considerable weight, which makes them difficult to handle. This means that for the purpose of securing the load, the belt ratchet in question must mostly be guided over the load or load to be secured together with tension hooks and positioned accordingly. This is sometimes complex and cumbersome for the operator. The invention aims to provide a remedy here overall.

The invention is based on the technical problem of developing such a Spannvor direction so that the operation and handling are simplified.

To solve this technical problem, the invention proposes in a generic clamping device that tensile functional elements are made of a different material than tensile decoupled functional elements.

In the context of the invention, a distinction is therefore made between the individual functional elements of the clamping device. The functional elements subjected to tension elements are those that transmit or absorb tension from the respective clamping device to the clamping device. Typically, these tensile functional elements include at least the base frame and the winding shaft rotatably mounted in the base frame or a ratchet lock belonging to the winding shaft. Instead of the winding shaft, however, the ratchet locking mechanism - if present - can absorb the tension transmitted from the respective tensioning device to the tensioning device, whereas the winding shaft acts as a tension-decoupled functional element in such a case.

In fact, in the example described, the force brought up by the tensioning means is deflected more or less by the winding shaft and transferred to a ratchet wheel with teeth, which defines the previously mentioned ratchet mechanism in connection with an associated pawl. In any case, in such a case, the ratchet wheel and the pawl and therefore the ratchet mechanism are primarily used to absorb the tensile forces, so they are designed as tensile functional elements, whereas the winding shaft largely deflects the applied tensile force or the tensile forces and consequently acts as a tensile decoupled functional element.

A distinction must be made between other tension-decoupled functional elements, that is to say functional elements that are not, or only slightly, acted upon by the tension built up by the tensioning means. This regularly includes at least the handle (in addition to the winding shaft mentioned above). Such tensile decoupled functional elements absorb 10% or less of the tensile force - if at all. Actuating forces act primarily.

Due to the recourse made according to the invention to different materials for on the one hand the tensile and on the other hand the tensile coupled functional elements can significantly reduce the weight of the stressed clamping device. The invention is based on the further knowledge that the material for the functional elements subjected to tension generally has a density of more than 7 g / cm ³ . In contrast, the material for the tension-decoupled functional elements usually has a density of less than 2 g / cm ³ .

As a result, the weight of a tensioning device according to the invention can generally be reduced by at least 10% compared to a conventional tensioning device. Usually a weight reduction of 20% and more is observed, with weight reductions of up to around 30% compared to conventional clamping devices. This significantly simplifies the handling of the tensioning device when securing the load.

The invention is based on the further knowledge that in the tensioning device described the functional elements subjected to tension account for approximately 60 to 70% of the weight and accordingly the tension-decoupled functional elements contribute 30 to 40% by weight. Since the density of the tension-decoupled functional elements is less than 1/3 of the tension-loaded functional elements, the weight of the tension-decoupled functional elements can be reduced to about 1/3 or even less compared to conventional clamping devices. In conjunction with the estimates given above, this then leads to the described weight reductions of at least 10% up to 30% and even more compared to a clamping device, which is consistently made from the material with a density of more than 7 g / cm ³ is. The invention takes into account that the functional elements subjected to tension are generally made from a material with a tensile strength of more than 500 N / mm ² (500 MPa). In particular, materials are used at this point which have a tensile strength of more than 1000 N / mm ² (1000 MPa) and preferably more than 2000 N / mm ² (2000 MPa). The tensile strength is regularly determined in accordance with DIN EN 10025.

In contrast, a material that is manufactured with a tensile strength of more than 100 N / mm ² (100 MPa) is sufficient for the tension-decoupled functional elements. The tensile strength for the tensile-decoupled functional elements is preferably 500 N / mm ² (500 MPa), with the tensile strength being able to be measured similarly to the previous one. Due to the different requirements for tensile strength, it is also explained that at this point materials with different densities can be used and consequently the total weight of the clamping device according to the invention can be reduced compared to conventional clamping devices as outlined.

In fact, plastic in particular, possibly with additives or inclusions, has proven to be particularly favorable as a material for the tension-decoupled functional elements. This means that the plastic used can be equipped with reinforcement, which can be inlaid steel, a steel mat, etc. For reasons of simple production, however, fiber-reinforced plastic is generally used at this point, i.e. H. the plastic has embedded fibers.

The fibers are mostly short fibers with a fiber length of less than 10 mm and preferably with a fiber length of 5 mm and very preferably with a fiber length of 1 mm and less. Because such short Fibers can be introduced into plastic granulate without any problems and processed together with the granulate by extrusion, so that according to the invention the tension-decoupled functional elements can be manufactured particularly advantageously in the course of an extrusion process. This reduces the production costs.

In any case, such fiber-reinforced plastics easily have tensile strengths of more than 100 N / mm ² (100 MPa), even tensile strengths of 1000 N / mm ² (1000 MPa) can be achieved. That depends on the proportion and design of the fibers introduced. In fact, it has proven itself at this point if glass fibers, carbon fibers, aramid fibers or comparable synthetic fibers are used as fibers, which of course can also be mixed with one another. Alternatively or additionally, however, natural fibers can also be used. These natural fibers can be flax, flanf, sisal, jute or the like. The weight fraction of the fibers in the fiber-reinforced plastic for setting the tension-decoupled functional elements is generally less than 50% by weight based on the plastic mass. As a rule, even proportions by weight of the fibers of less than 25% by weight based on the plastic mass are observed and adjusted. This enables tensile strengths of several 100 N / mm ² (100 MPa) to be represented and, on the other hand, densities are observed for those fiber-reinforced plastics that are well below 2 g / cm ³ , mostly even less than 1.5 g / cm ³ be. As a result, the density ratio compared to the material for the functional elements subjected to tension is once again significantly improved. This is because the material for the functional elements subjected to tension is mostly steel and, in particular, high-strength steel, which has a density of almost 8 g / cm ³ , so that density ratios between the material for the functional elements subject to tension and that for the functional elements that are decoupled from tension are typically 3: 1 to 5: 1 and more can be realized.

The clamping device according to the invention is consequently designed overall as a hybrid clamping device, because different materials are used at this point depending on the tension applied. In fact, the procedure is usually such that at least the base frame and, if applicable, the winding shaft or the ratchet mechanism are made of steel as functional elements that are subjected to tension. On the other hand, plastic and, in particular, fiber-reinforced plastic will generally be used as tension-decoupled function elements for the positioning of the flange handle and, if necessary, the winding shaft. As a result, the weight of the clamping device according to the invention can be significantly reduced compared to conventional clamping devices, which are made entirely of steel. This is where the main advantages can be seen.

In the following the invention is explained in more detail with reference to a drawing showing only one embodiment; show it:

Fig. 1 shows the tensioning device according to the invention in the form of a belt ratchet in perspective and

FIG. 2 shows a plan view of the belt ratchet according to FIG. 1 The figures show a tensioning device which, according to the exemplary embodiment, is a belt ratchet, ie a tensioning device for only indicated tensioning means or plastic belts 1. The plastic belts 1 are plastic fabric belts. In fact, two plastic belts 1 are implemented at this point, with a plastic belt 1a being connected with its fixed end directly to a base frame 2. Another second plastic belt 1 b is looped with its loose end into a winding shaft 3 rotatably mounted in the base frame 2. The winding shaft 3 is equipped with a ratchet mechanism 4, 5, which is composed of two ratchet wheels 4 with teeth on both sides of the winding shaft 3 on the one hand and a pawl 5 on the other.

As evidenced by the top view according to FIG. 2, the pawl 5 is a locking slide which can be displaced against a spring force in the longitudinal direction relative to a handle 6. The handle 6 is rotatably held on the base frame 2, coaxially with the winding shaft 3, or is connected to the base frame 2. With the aid of the handle 6, the winding shaft 3 can be driven.

For this purpose, the handle 6 can be subjected to the winding shaft 3 in a rotating and manual manner about its common axis. In this case, as soon as the pawl 5 or the locking slide is in engagement with the teeth of the relevant ratchet wheel 4, the winding shaft 3 is rotated so that the loose end of the plastic belt 1b looped into it is increasingly tensioned. To release the tensioning device or belt ratchet, the pawl 5 or the locking slide must be removed from its engagement with the teeth of the associated locking wheel 4 by an operator against the force of a spring. In any case, the relevant tensioning means or the associated plastic belt 1 for Zugüber transmission can be applied by a corresponding application of the handle 6. In this way, for example, a load or charge can be releasably fixed on a loading surface with the aid of the clamping device. During this process, corresponding tensioning forces or tensile forces are transmitted to the tensioning device or belt ratchet.

The individual functional elements of the tensioning device can be divided into tension-loaded functional elements 2, 4, 5 and tension-decoupled functional elements 3, 6. In the context of the exemplary embodiment and not by way of limitation, the functional elements 2, 4, 5 subjected to tension are, on the one hand, the base frame 2 and, on the other hand, the ratchet mechanism 4, 5 or the ratchet wheel 4 and the pawl 5. In contrast, the tension-decoupled functional elements 3, 6 In the exemplary embodiment, the winding shaft 3 and the handle 6. According to the invention, the functional elements 2, 4, 5 to which tension is applied are now made from a different material than the tension-decoupled functional elements 3, 6. In fact, according to the exemplary embodiment, steel or high-strength steel is used for the tensile functional elements 2, 4, 5, whereas the tensile decoupled functional elements 3, 6 are made of plastic and, in particular, a fiber-reinforced plastic.

As a result, the tension-loaded functional elements 2, 4, 5 have a density of more than 7 g / cm ³ , whereas the tension-decoupled functional elements 3, 6 have a density of less than 2 g / cm ³ and in particular even 1.5 g / cm ³ and less is observed. This creates between the tension-loaded and tension-decoupled functional elements 2, 4, 5; 3, 6 a density ratio of approx. 3: 1 or 4: 1 and more.

The functional elements 2, 4, 5 subjected to tension or the steel used typically has a tensile strength of more than 1000 N / mm ² (1000 MPa). In contrast, a tensile strength of more than 100 N / mm ² (100 MPa) is observed for the tension-decoupled radio elements 3, 6 and the fiber-reinforced plastic used here. Usually the tensile strength is even more than 500 N / mm ² (500 MPa).

The plastic for positioning the tension-decoupled functional elements 3, 6 is designed with embedded fibers in the form of glass fibers, carbon fibers and / or aramid fibers. The proportion by weight of the fibers in question is less than half of 50% by weight. In addition, short fibers with a fiber length of less than 5 mm and in particular those with a fiber length of less than 1 mm are mostly used in this context, so that the fibers in question can be mixed with plastic granulate without any problems and can be extruded together to form the tension-decoupled functional elements 3, 6 and specifically on the one hand the winding shaft 3 and on the other hand the flange hub 6 by extrusion and in particular injection molding.

The invention recommends thermoplastic plastics and here in particular polyamide (PA), polycarbonate (PC), polyethylene terephthalate (PET) or even polyoxymethylene (POM) as suitable plastics for the position of the tension-decoupled functional elements 3, 6. The plastics in question can be produced individually or even in mixtures. Glass fibers or carbon fibers have been introduced into the plastic in question in order to

in this way by injection molding the relevant tension-decoupled functional element 3, 6 to be able to manufacture.

Claims

Patent claims:

1. Tensioning device, in particular a belt ratchet, with a base frame (2), further with at least one winding shaft (3) rotatably mounted in the base frame (2), and with a handle (6) for driving the winding shaft (3), with the base frame ( 2) and the winding shaft (3) one or more tensioning means (1) are connected for tension transmission, characterized in that tension-loaded functional elements (2, 4, 5) are made from a different material compared to tension-decoupled functional elements (3, 6).

2. Device according to claim 1, characterized in that the zugbeauf bumped functional elements (2, 4, 5) made of a material with a tensile strength of more than 500 N / mm ² , in particular more than 1000 N / mm ² and preferably more are made than 2000 N / mm ² .

3. Device according to claim 1 or 2, characterized in that the train-decoupled functional elements (3, 6) are made of a material with a tensile strength of more than 100 N / mm ² and preferably of 500 N / mm ² and more.

4. Device according to one of claims 1 to 3, characterized in that the material for the tensile functional elements (2, 4, 5) has a density of more than 7 g / cm ³ .

5. Device according to one of claims 1 to 4, characterized in that the material for the tension-decoupled functional elements (3, 6) has a density of less than 2 g / cm ³ . 6. Device according to one of claims 1 to 5, characterized in that the material for the tension-decoupled functional elements (3,

6) is a plastic, possibly with storage.

7. Apparatus according to claim 6, characterized in that the plastic has embedded fibers.

8. Apparatus according to claim 6 or 7, characterized in that glass fibers, carbon fibers or aramid fibers are used as artificial fibers or natural fibers such as flax, flanf, jute, sisal individually or in combination.

9. Device according to one of claims 6 to 8, characterized in that the weight fraction of the fibers is less than 50 wt .-% and in particular 25 wt .-% and less based on the plastic mass.

10. Device according to one of claims 1 to 9, characterized in that the base frame (2) and a ratchet mechanism (4, 5) are made of steel as functional elements (2, 4, 5) to which tension is applied.

11. Device according to one of claims 1 to 10, characterized in that the winding shaft (3) and the flange hub (6) are made as tension-decoupled functional elements (3, 6) made of plastic, in particular fiber-reinforced plastic.