WO2018056852A1

WO2018056852A1 - Method of manufacturing a flexible member with a shock absorber and a flexible member with a shock absorber

Info

Publication number: WO2018056852A1
Application number: PCT/PL2017/000089
Authority: WO
Inventors: Łukasz SKRYPLONEK
Original assignee: Skryplonek Lukasz
Priority date: 2016-09-21
Filing date: 2017-09-20
Publication date: 2018-03-29
Also published as: PL418785A1

Abstract

The present invention relates to a method for manufacturing a flexible member with a shock absorber, the said method including the following steps: providing a protecting spring-shaped device (1) with periodically variable outside diameter of the protecting device (1), providing a flexible member (2) with a length greater than the length of the protecting device (1), placing the protecting device (1) on the flexible member (2), attaching the first end (3) of the protecting device (1) to the flexible member (2) on one of its ends, stretching the protecting device (1) by using tensile force, attaching the second end (4) of the protecting device (1) to the flexible member (2) while the protecting device (1) is kept in stretched condition, after which the tensile force is removed. The present invention relates also to a flexible member with a shock absorber manufactured with the use of the said method.

Description

Method of manufacturing a flexible member with a shock absorber and a flexible member with a shock absorber

The present invention relates to a method of manufacturing a flexible member with a shock absorber and to a flexible member with a shock absorber, the said member having such properties that ensure high breaking strength, high resistance to abrasion and mechanical damage, as well as the absorption of shocks caused by sudden pulls. The present invention is used in safety equipment installed on climbing routes, as well as for walking animals, in particular for walking dogs on leash. This invention may also be used for protecting fluid and electric conduits, such as high voltage conduits, as well as in mooring lines for watercrafts.

In the technical field of climbing equipment, there are known lanyards and absorbers which act as a safety measure during works at height or rock climbing. In general, this kind of equipment comprises a rope or band proper which is provided with an absorber, e.g. a belt wound and placed in an openable protective cover. In the case when a person protected with such safety equipment falls from a climbing wall, the protective cover opens and/or breaks open, and the belt stowed inside unwinds, gradually absorbing the energy created as the protected person falls. Such a solution is disclosed inter alia in US5174410 (A). Commercially available lanyards used during works at height, for instance the Flex-ABS COMBI Y lanyard manufactured by Climbing Technology by Aludesign S.p.A., comprise, except for the said webbing absorber, two elastic arms which are attached to the fall arrest system's attachment points. The said arms are provided with a shock-absorbing structure which allows them to be easily manipulated, in particular to be detached and reattached, while also increases the shock-absorbing properties of the system. The structure of elastic arms is analogous to the structure disclosed in US6085802 (A). The invention disclosed in US6085802 (A) is a continuously woven web comprising a first woven region interwoven with a plurality of yarns to define a first weave pattern and a second woven region forming a continuous weave with the first woven region and having a continuation of the yarns. The yarns are attached to the second woven region at a distal end thereof. The second woven region has a length defined by a length between a first end positioned adjacent a termination of the first weave pattern and the distal end. In the second woven region, the yarns have a greater elasticity in aggregate and a shorter length than the second woven region. Upon the application of a tensile force to the webbing, the yarns in the second woven region may elongate to a length limited by the length of the second woven region. In one of the embodiments of the quoted invention, the second woven region folds back upon itself in a serpentine manner and the yarns loosely weave longitudinally through the alternately folded second woven region. Thus, upon the application of a tensile force to the lanyard, the elastic yarn stretches to a point at which the alternately folded second woven region becomes stretched and substantially unfolded. Due to the lack of any shield or covering, such solutions are not resistant to either abrasion or cuts caused by rocks or sharp edges of metal structures and consequently there is a risk that the lanyard's strength may be significantly reduced when it is accidentally cut or torn. Moreover, the structure of the elastic arms causes their shock-absorption properties to undergo degradation with time, in particular after the rope has been repeatedly stretched to its maximum stress limit. A shock absorber of a similar design was used in a leash commercially offered as "Zero Shock Leash" by EzyDog. This leash represents disadvantages similar to the disadvantages described above. It is important to note that the sewn connection of the shock-absorption webbing reduces the strength of the material, since it involves physical interruption into its structure.

US2012074186 (A1 ) discloses a tool-hanging rope which includes an extendable and retractable connecting band unit and two retaining ring units. The connecting band unit includes a pleated cloth band and a plurality of main resilient strings extending within the pleated cloth band along the length of the connecting band unit and connected to the pleated cloth band by knitting. The retaining ring units are fastened respectively to two opposite ends of the connecting band unit. When a force is applied to the connecting band unit, a plurality of main resilient strings is extended due to their elastic properties, the extension being limited by the length of the simultaneously stretched pleated cloth band, and having substantially the same direction as the orientation of the internal main resilient strings. Such design also fails to offer properties which would ensure protection against damage to its external surface, such as abrasion and cuts, and thus fails to offer sufficient protection to a person who falls, for example when performing rock climbing.

Document US2006266581 (A1) discloses a shock absorbing lanyard in the form of a one- piece webbing. The shock absorbing lanyard has a tubular-shaped high strength outer sheath and a high elongation member inside of the outer sheath. The outer sheath and the high elongation member are secured together at spaced apart connection locations and the high elongation member is generally not secured to the outer sheath between the connection locations. Heat treatment shrinks the length of the high elongation member while the outer sheath does not shrink from the heat treatment. As a result, the outer sheath gathers together in an accordion-like arrangement between the connection locations. A tensile load applied to the shock absorbing lanyard stretches the high elongation member and unfolds the gathered outer sheath. Thus, strength properties are provided by the high strength outer sheath, while shock absorption properties are provided by the high elongation member, which absorbs energy as it stretches or elongates. Although a high strength outer sheath is used, the lanyard may still be torn and cut, for example by sharp rock edges. Hence, the strength of the lanyard may be significantly reduced and the lanyard may not offer sufficient fall protection.

Document WO2016093717 (A1 ) discloses an elongated flexible member with a protecting device. The elongated flexible member may take the form of inter alia a rope or a leash. In one of the embodiments, the protecting device takes the form of a spring with periodically variable outside diameter of individual coils and with at least two areas having a maximum outside diameter and at least two areas having a minimum outside diameter. The structure of the protecting device provides protection against biting and chewing, in particular by dogs. The protecting device is attached to two opposite ends of the elongated flexible member, e.g. a leash made of rope, by means of sewing or clamping suitable attachment elements. The use of the attached spring-shaped protecting device and the possibility to elongate the weave in the leash make such a flexible member with a protecting device display shock absorbing properties and absorb stronger jolts caused by a dog pulling on the leash. Also, the leash is thus protected against biting.

The main object of the present invention is to provide a manufacturing method for a flexible member with a shock absorber which allows the production of such an elongated flexible member with a shock absorber that serves as a means of protection for the flexible member, in particular against abrasion and cuts caused by sharp objects (alternatively against biting) and that displays improved tensile energy absorption characteristics, while retaining its structural strength, the said method being simple, economically advantageous and not limited by the need to use specialized manufacturing equipment. It is also desired to provide such a manufacturing method for a flexible member with a shock absorber that offers the possibility to adjust the tensile energy absorption characteristics. The present invention unexpectedly solves the above described technical problems.

In the first aspect of the present invention, a method of manufacturing a flexible member with a shock absorber is provided, characterized in that it includes the following steps:

a) providing a protecting device in the form of a spring,

b) providing a flexible member having a length greater than the length of the protecting device,

c) placing the protecting device on the flexible member,

d) attaching the first end of the protecting device to the flexible member,

e) stretching the protecting device by using tensile force, f) attaching the second end of the protecting device to the flexible member while the protecting device is kept in stretched condition, and subsequently removing the tensile force, wherein the inside diameter of the protecting device is greater than the outside diameter of the flexible member.

Preferably, the protecting device has a variable inside diameter and more preferably the protecting device has a periodically variable inside diameter.

In a preferred embodiment of the present invention, the protecting device is placed on the flexible member using an intermediate cylindrical insert according to the following procedure: in the first step the insert is slid on the flexible member, in the second step the protecting device is placed on the cylindrical insert and in the final step the cylindrical insert is removed leaving the protecting device on the flexible member.

In another preferred embodiment of the present invention, the protecting device is placed on the flexible member by fastening the protecting device and/or the flexible member in an apparatus producing rotary motion, substantially coaxial with the protecting device and/or the flexible member, and by gradually inserting the protecting device on the flexible member while retaining the rotary motion of the protecting device and/or the flexible member.

In another preferred embodiment of the present invention, the protecting device rotates in the direction opposite to the rotation direction of the flexible member.

Preferably, the rotational speed of the flexible member is smaller than the rotational speed of the protecting device.

Another preferable solution is to use various force at step e) depending on the desired energy absorption characteristics.

In the preferred embodiment of the present invention, the protecting device is made of metal wire or of another material having hardness corresponding to hardness values between HRG and HRA in Rockwell scale.

In another embodiment of the present invention, the flexible member is a braided rope, a stranded rope, an electric cable or a fluid conduit.

In another embodiment of the present invention, the procedure of attaching the first end of the protecting device and/or the second end of the protecting device to the flexible member comprises threading the first end of the protecting device and/or the second end of the protecting device through the flexible member or clamping an attachment element, preferably hose clamp, a clamping ring, a clamping sleeve or a magnetic clamp. Preferably, the attachment elements are additionally clamped around at least one intermediate region which is located between the first end and the second end of the protecting device, in the area where the protecting device has the smallest inside diameter.

In the second aspect of the present invention a flexible member with a shock absorber is provided, which comprises a flexible member and a spring-shaped protecting device placed around it, the protecting device being attached to the flexible member on both sides of the flexible member, and which is characterized in that the flexible member is longer than the protecting device, the inside diameter of the protecting device is greater than the outside diameter of the flexible member, and the flexible member is compressed in such a manner that it gathers together and/or folds in the space created between the inside diameter of the protecting device and the outside diameter of the flexible member, thus filling the said space.

In the preferred embodiment of the present invention, the flexible member is a braided rope, a stranded rope, an electric cable or a fluid conduit.

In another preferred embodiment of the present invention, the protecting device is made of metal wire or of a material having hardness corresponding to hardness values between HRG and HRA in Rockwell scale.

In another embodiment of the present invention, the procedure of attaching the first end and/or the second end of the protecting device to the flexible member comprises threading the first end of the protecting device and/or the second end of the protecting device through the flexible member or clamping an attachment element, preferably a hose clamp, a clamping ring, a clamping sleeve or a magnetic clamp.

Preferably, the attachment elements are additionally clamped around at least one intermediate region which is located between the first end and the second end of the protecting device, in the area where the protecting device has the smallest inside diameter.

The method for manufacturing a flexible member with a shock absorber according to the present invention allows manufacturing an elongated member whose properties ensure that the said member is protected against biting and chewing by animals, in particular by dogs, and also against abrasion and cuts caused e.g. by sharp edges of rocks or construction elements. These properties are provided by a spring-shaped device made of hard material, preferably of wire. More preferably, the protective properties of the flexible member are provided by a protecting device whose coils have a periodically variable inside diameter. Moreover, the protecting device is an additional element which influences the strength of the flexible member, as it offers an additional protection even when the flexible member is broken. In addition, the application of the manufacturing method according to the present invention resulted in obtaining improved tensile energy absorption characteristics, i.e. by pulling the protecting device over the flexible member during the manufacturing process and by attaching the second end of the protecting device to the flexible member while the protecting device is kept in stretched condition, it was possible to compress the material of the said member - in the case of ropes this member being the core material (and the braid) - in the space created between the outside diameter of the flexible member and the inside diameter of the protecting device (the inside diameter of the protecting device is greater than the outside diameter of the flexible member). In the case of a protecting device with periodically variable inside diameter of coils, the flexible member is compressed and/or gathers together in the region of the greatest inside diameter of the protecting device. In the case when the flexible member comprises a braided rope, the braid of such rope, which is in compression in the space formed by the largest inside diameter of the protecting device, undergoes compression with core expansion, in the fashion of striated muscles tissue. Such behavior is possible due to a specific alignment of core filaments and to an adequate braid density. On the other hand, when the flexible member comprises a twisted rope, which typically does not have a braid and whose core comprises twisted filaments, the characteristic design of such rope does not permit the rope's structure to expand as the system is compressed. In such case, the whole rope assumes a characteristically undulating shape, and folds in the spaces formed by the largest inside diameter of the protecting device, contacting the protecting device in at least one point (typically across the whole region) and thus allowing the accommodation of a rope of greater length than the length of the protecting device. Flexible members comprising electric cables and fluid conduits will show a similar behavior, as their design does not permit the structure's expansion in the fashion of striated muscles tissue, either. Compression of this member (its gathering) in the void spaces of the protecting device-flexible member system, effected improved absorption characteristics by increasing the actual length of the flexible member in relation to the length of the protecting device, and hence by defining a new elongation limit of the complete system comprising the flexible member with a shock absorber. As a result, elongation of the flexible member is limited only by its specific length increased slightly by the elasticity of the flexible member's material, while the actual absorbing properties are provided by the spring-shaped protecting device made of a hard material, preferably of wire. Thus, a high-strength flexible member with a shock absorber is provided, which is resistant to damage caused by external factors and which has improved shock absorbing properties. Additionally, the manufacturing process remains simple and does not require any highly specialized equipment, and as a result it is economically advantageous. In addition, providing a flexible member with a braid which has a cylindrical cross-section and with a void space which extends along the length of the member and which accommodates a high-strength core, results in increasing the total strength of the structure of the flexible member with a shock absorber. In the case when a rope is applied, it should be noted that the typically used braid weaving method is characteristic in that a space is left between individual filaments. As the core undergoes compression and the distance between individual filaments increases, the space between braid filaments also increases and causes the rope to compress along its full length as a result of periodic variation of the rope's diameter. In addition, the method for manufacturing a flexible member with a shock absorber according to the present invention allows simple adjustment of the desired shock absorbing characteristics already at the manufacturing stage, using the same set of constituent elements, by adjusting the force with which the protecting device is pulled over the flexible member prior to attaching the second end of the protecting device to the flexible member. Thus, no need exists to change either the complete system or .any of its constituent elements in order to manufacture flexible members with shock absorbers having various shock absorbing characteristics.

Exemplary embodiments of the present invention are illustrated in the drawing, in which Fig. 1 is an axonometric view of a fragment of the flexible member with a shock absorber in accordance with an embodiment of the present invention, Fig. 2 is a longitudinal cross section of the flexible member in accordance with an embodiment of the present invention, Fig. 3 is a side view of the protecting device in accordance with an embodiment of the present invention, Fig. 4 is a side view of the flexible member with a shock absorber in the maximally stretched state, Fig. 5 is a partial longitudinal cross section of an enlarged fragment of the flexible member with a shock absorber in the maximally stretched state in accordance with Fig. 4, Fig. 6 is a side view of the flexible member with a shock absorber in accordance with Fig. 4 in the unstretched state, Fig. 7 is a longitudinal cross section of the flexible member with a shock absorber in accordance with Fig. 6, Fig. 8 is an enlarged detail of the means for attaching protecting device to the flexible member in accordance with Fig. 7, Fig. 9 is a side view of the flexible member with a shock absorber in the maximally stretched state in accordance with another embodiment of the present invention, Fig. 10 is a side view of the flexible member with a shock absorber in accordance with Fig. 9 in the unstretched state, Fig. 11 is a side view of the flexible member with a shock absorber in the unstretched state in accordance with another embodiment of the present invention, Fig. 12 is a side view of the flexible member with a shock absorber showing an alternative embodiment of the attachment element, Fig. 13 is a side view of a fragment of the flexible member with a shock absorber showing intermediate attachment elements, Fig. 14 is a side view of the flexible member with a shock absorber comprising a protecting device having constant inside diameter and being in the maximally stretched state, in accordance with another embodiment of the present invention, Fig. 15 is a side view of the flexible member with a shock absorber in accordance with Fig. 14 in the unstretched state, while Fig. 16 is a diagram showing shock absorbing characteristics of the flexible members with shock absorbers in accordance with an embodiment of the present invention.

Example 1

Figures 1 - 8 show the first embodiment of the flexible member with a shock absorber in accordance with the present invention. The flexible members 2 are provided with shock- absorbing characteristics by being inserted into or otherwise attached to a protecting device 1 which has high hardness, high breaking strength, high resistance to abrasion and mechanical damage, and which displays properties ensuring the absorption of shocks caused by sudden pulls. Another embodiment of the present invention has been shown schematically in Figures 9 and 10, yet another embodiment - in Fig. 11 , and yet another embodiment - in Figures 14 and 15. Each embodiment of the present invention is manufactured in accordance with the method of this invention, as described in detail below.

The manufacturing method of the flexible member with a shock absorber can be divided into the following steps:

a) providing a protecting device 1 :

This step comprises providing a protecting device dedicated for a particular application. Depending on the form of the flexible member 2 to be inserted into or otherwise attached to a protecting device 1 , in particular depending on the geometrical dimensions of the said member, a protecting device 1 is provided that fits the flexible member 2. The protecting device 1 typically is a spring-shaped structure made of metal wire, and most preferably the said device has such a periodically variable inside diameter that there exist at least two areas having a minimum inside diameter and two areas having a maximum inside diameter. Fig. 3 shows a side view of a preferred embodiment of the protecting device 1. In alternative embodiments, the protecting device 1 may have only one area of a maximum inside diameter and two areas of a minimum inside diameter, which will be located on the ends of the protecting device 1. Another embodiment of the protecting device 1 is also possible, in which periodical variation of the inside diameter does not occur, as has been schematically shown in Figures 14 and 15, where the protecting device 1 has a constant inside diameter along its full length, the said diameter being greater than the outside diameter of the flexible member 2 in order to provide a space for the flexible member 2 to gather or expand. The present invention is intended to comprise a protecting device 1 which has a non-periodically variable inside diameter. Most preferably, the protecting device 1 is made of metal wire, but it is possible to make the protecting device 1 of a material having hardness corresponding to hardness values between HRG and HRA in Rockwell scale. The protecting device 1 can be manufactured using methods known in the art, for example by bending the wire in the case of a protecting device 1 made of metal wire, or by extrusion or casting in the case of a protecting device 1 made of plastic.

b) providing a flexible member 2:

This step comprises providing a flexible member 2 which will be inserted into or otherwise attached to a protecting device 1. The flexible member 2 may be a braided rope, a stranded rope, a fluid conduit or an electric cable. However, potential forms of the flexible member 2 are not limited to the ones presented above, and one skilled in the art will be able to apply the method according to the present invention to other flexible members 2 not listed above, without departing from the scope of the present invention described in claims. For example, in the case when the application comprises dog leashes, the flexible member 2 may be preferably a polypropylene or polyamide braided rope. Ropes of this type have a structure consisting of the core 6 and the braid 7, as has been shown in the longitudinal cross section in Fig. 2. The rope core 6 consists of a great number of high-strength filaments, while the braid 7 compresses and protects the core, giving the rope its oval shape. The braid 7 consists of stiffer filaments braided with the use of special spindles. The change of the density ratio between the core 6 and the braid 7 allows smaller or greater rope compression. Increasing the density of the core 6 in the braid 7 decreases the compressibility of the rope. c) placing the protecting device 1 on the flexible member 2:

The next step of the method in accordance with the present invention comprises placing the protecting device 1 on the flexible member 2. This step may be performed in a suitable manner without departing from the scope of the present invention. This step may be for example performed by placing the protecting device 1 in an apparatus which puts the protecting device 1 in rotary motion, substantially coaxial with the flexible member 2 and/or the protecting device 1. In such case, the flexible member 2 is secured in a stationary support clamp and aligned in such a manner that the flexible member 2 and the protecting device 1 are placed coaxially and opposite each other. The protecting device 1 is put in rotary motion and subsequently the flexible member 2 is gradually inserted into the inner space of the protecting device 1 , the said rotary motion facilitating the insertion of the flexible member 2 by putting the said protecting device 1 in screw motion. In an alternative embodiment of this step, the flexible member 2 may be also placed in an apparatus which puts the flexible member 2 in rotary motion, and as the protecting device 1 is gradually inserted onto the flexible member 2, both elements remain in rotary motion, rotating in opposite directions. The step comprising the insertion of the protecting device 1 onto the flexible member 2 may also be performed using intermediate elements, such as an intermediate cylindrical insert made of for example plastic. The use of such an intermediate cylindrical insert may be preferable, when the flexible member 2 comprises braided or stranded ropes, whose stiffness is significantly lower than the stiffness of for example electric cables. Such an intermediate cylindrical insert is placed on the flexible member 2, then the protecting device 1 is placed on the intermediate cylindrical insert, and upon the completion of this procedure the intermediate cylindrical insert is removed, leaving the protecting device 1 inserted on the flexible member 2. Placing the protecting device 1 on the intermediate cylindrical insert may be performed in accordance with the above examples. Alternatively, the protecting device 1 may be first placed on the cylindrical insert and subsequently inserted on the flexible member 2, followed by removing the intermediate cylindrical insert. The insertion of the protecting device 1 onto the flexible member 2 may be also performed using other methods known in the art, without departing from the scope of the present invention. d) attaching the first end 3 of the protecting device 1 to the flexible member 2:

The protecting device 1 may be attached to the flexible member 2 using an invasive or a non-invasive method, depending on the structure and the predicted application of the flexible member 2. The invasive method is associated with perforating the flexible member 2. The attachment is effected by threading/puncturing the first end 3 of the metal protecting device 1 through an opening (in order to ensure durable attachment, the axis of the opening should run through the widest point of the circumference of the flexible member 2) and subsequently by bending the first end 3 by 90 degrees. The above-described method for attaching the protecting device 1 to the flexible member 2 is best illustrated in the partial longitudinal cross section of Fig. 5 and in the longitudinal cross sections of Fig. 7 and Fig. 8. The bending and the attachment area may be additionally protected by placing a clamping sleeve in the attachment area. The invasive attachment method may be applied in the case of such flexible members 2 which do not lose important properties or strength due to the damage of their internal structure. Such members may be for example a polypropylene or polyamide braided rope. In order to avoid compromising the rope's structure, the perforation of the braid 7 by a wire made of metal or of durable elastomer may run between the filaments of the rope's braid 7, and subsequently between the fibers of the core 6, while the pressure exerted by clamping an aluminum sleeve additionally compresses the filaments in the area without significantly weakening the rope's structure. In the non-invasive method, on the other hand, the attaching effect is achieved by clamping the clamping element 5, which may comprise for example a hose clamp, a clamping ring, a clamping sleeve or a magnetic clamp, on the flexible member 2. This type of attachment is schematically shown in Fig. 12. In order to make the attachment more durable, two clamping elements 5 may be used between a single coil of the protecting device 1. Such case is illustrated in Fig. 13, which is a side view of the flexible member with shock absorber. The use of two clamping elements 5 is aimed at enabling the flexible member 2 (e.g. comprising an electric cable) to be cut in the areas between the clamping elements 5. Moreover, a single coil of protecting device 1 which has a greater inside diameter and which is left between the clamping elements 5 acts as an additional protection of the crucial area against damage (additionally protecting the flexible member 2, comprising for example an electric cable) and ensures elasticity between the clamping elements 5 (clamping ties). Two clamping elements 5 located at a small distance and the adjacent material of the protecting device comprising wire, could locally make the flexible member 2 stiffer, thus limiting its functionality. The non-invasive method may be applied in the case when the protecting device 1 is attached to such flexible members 2 in which compromising their structure could cause compromising or damaging their internal structure, and this fact would in turn cause the flexible member 2 to lose its properties or strength to a significant degree. Such applications comprise for example electric cables, hydraulic hoses or twisted ropes, the puncturing of which would cause them to lose their functionality.

e) stretching the protecting device 1 :

Stretching of the protecting device 1 on the flexible member 2 is performed after the protecting device 1 is attached or temporarily secured at one of its ends 3, 4. Depending on the desired absorbing characteristics, and/or type and structure of the flexible member 2, the protecting device is stretched to the desired length (or with the desired force). This step may be performed with the use of technical means known in the art. In one of the possible embodiments of this step, after the elasticity modulus of the protecting device 1 is calculated, a distance is defined into which the protecting device 1 will be stretched, the said distance being the resultant of the said parameter (elasticity modulus) and the compression limit of the flexible member 2, for instance a rope. The above step is aimed at adjusting the geometric parameters of the system in such a way that a desired compression ratio of the flexible member 2 is obtained in the void spaces of the protecting device 1 without losing its absorbing properties and the integrity of the flexible member 2 with the protecting device 1. After the first clamping element 5 is attached to the first end 3 of the protecting device 1 , the protecting device 1 is stretched on the flexible member 2 to a precisely defined length, and then the second end 4 of the protecting device 1 is attached. The result of this operation is the flexible member 2 with a protecting device 1 comprising a shock absorber. If the value of the elasticity modulus of the protecting device 1 is not high, the stretching procedure of the protecting device 1 may be performed manually, thus ensuring relative accuracy and precision. In the case when the value of the elasticity modulus of the protecting device 1 is higher, the stretching procedure may be performed with the use of pulley blocks known in the art. Obviously, the potential stretching methods are not limited to the one presented above and every method allowing the protecting device 1 to be stretched to a desired length with the use of appropriate force will be recognized as suitable to complete this step.

f) attaching the second end 4 of the protecting device 1 to the flexible member 2:

The next step consists in attaching the second end 4 of the protecting device 1 to the flexible member 2 with the protecting device 1 stretched to a desired length (alternatively with the use of a desired tensile force). This attachment procedure may be analogous to the one presented at the step of attaching the first end 3 of the protecting device 1 to the flexible member 2. In addition, to secure the protecting device 1 in place on the flexible member 2 and to increase its shock absorption efficiency, clamping elements 5 may be used in each region (or only in some regions) where the protecting device 1 contacts the flexible member 2 (in the case of a protecting device 1 with variable inside diameter). The said regions will be located in the spaces formed by the minimum inside diameter of the protecting device 1. The attaching of intermediate clamping elements 5 is illustrated in Fig. 13. After the stretched protecting device 1 is attached, it is compressed and resumes its original shape, while the whole structure acquires desired shock absorbing characteristics. Depending on the particular type of the flexible member 2, the protecting device 1 may provide shock absorption by utilizing undulation of the flexible member 2 (see embodiments illustrated in Figures 10, 11 and 15) or local expansion of the flexible member 2, in particular of its core (see embodiments illustrated in Figures 6, 7 and 8). In the case of a polypropylene or polyamide braided rope, in which the density of the core 6 and of the braid 7 allows such phenomenon, the rope expands in those spaces in which the protecting device 1 has maximum inside diameter (in the case of a protecting device 1 with variable inside diameter). The material of the core 6 undergoes compression and expands in the fashion of striated muscle tissue, as illustrated in the cross sections of Figures 7 and 8. Such solution may be implemented in the case of shock absorbing dog leashes or climbing ropes, giving the rope with a shock absorber not only the property to absorb sudden shocks on the rope, but also protection against abrasion. In the case when the structure of the flexible member 2 does not allow the flexible member 2 to expand (for example in the case of an electric cable or a twisted rope), after the stretched protecting device 1 is inserted on such a flexible member 2 and after the protecting device 1 compresses, the flexible member 2 assumes an undulating shape and, depending on the structure of the protecting device 1 , it may contact the protecting device 1 in a plurality of regions (see Fig. 10) or adjoin the protecting device 1 along a certain length thereof, if the diameter of the said protecting device 1 has a barrel- shaped configuration (see Fig. 1 1 ). Such solution may be used in high- and medium-voltage transmission lines, in order to absorb shocks caused by sudden gusts of wind and to protect the said lines against friction, which is highly detrimental in electric energy transmission systems.

Fig. 16 is a diagram showing the shock absorbing characteristics of a flexible member with a shock absorber in accordance with one of the embodiments of the present invention, as compared with reference systems. The shock absorbing characteristics were determined with the use of a polypropylene rope with braid (32 spindles) having an outside diameter of 8 mm and a length of 120 cm. The core of the rope comprised a number of substantially parallel filaments and its outside diameter was 5.5 mm, while the braid thickness was 1.25 mm. A polypropylene rope without a protecting device 1 was used in the reference measurement A. Further measurements included polypropylene ropes with a protecting device 1 , manufactured in accordance with the method of the present invention and using three different tensile force values: F_B=0 N, FC=50 N, F_D=100 N used to stretch the protecting device 1 prior to the insertion thereof onto the flexible member 2. The protecting device 1 comprised a spiral 32 cm in length, with a 5 mm pitch, made of stainless steel wire, 1.4 mm in diameter. The protecting device 1 comprised periodically variable inside diameter, the minimum inside diameter being 8 mm, and the maximum inside diameter being 14 mm. The full length of the protecting device 1 comprised 5 periods. The shock absorbing characteristics were illustrated as a function of the relative elongation of the rope with a shock absorber and the load applied to the said rope. As seen in the diagram in Fig. 16, rope A (without the protecting device 1 ) and rope B (with the protecting device 1 attached without prior stretching) show similar shock absorbing characteristics, i.e. the application of a force (expressed as the applied load) causes a similar relative elongation of the flexible member 2, the elongation being due to own elasticity of the rope used. In the case of rope C, in which the protecting device 1 was stretched with the force of 50 N, the length of the complete system is reduced due to the compression of the flexible member 2 in the void spaces between the maximum inside diameter region of the protecting device 1 and the inside diameter of the flexible member 2 (analogically to the situation represented in Figures 6, 7 and 8). The length of the system was reduced by 15 cm, which indicates that such length of the flexible member 2 was accommodated in the said void spaces. As a result of applying a load to the rope with a shock absorber C, the system undergoes relative elongation, which indicates improved elasticity and hence, shock absorbing properties. Rope D, stretched with a force of 100 N, was reduced in length by 25 cm and upon the application of a force undergoes even greater elongation, which indicates more preferable shock absorbing properties for a particular application (for example a dog leash). The above- described test results confirm the possibility to predefine particular shock absorbing characteristics with the use of the same system, i.e. the same flexible member 2 and the same protecting device 1 , solely by alternating the force used to stretch the protecting device 1 and thus the results also clearly confirm the universal character of the present method for manufacturing a flexible member with shock absorber.

Claims

1. A method of manufacturing a flexible member with a shock absorber characterized in that it includes the following steps:

a) providing a spring-shaped protecting device (1 ),

b) providing a flexible member (2) having a length greater than the length of the protecting device (1 ),

c) placing the protecting device (1 ) on the flexible member (2),

d) attaching the first end (3) of the protecting device (1 ) to the flexible member (2), e) stretching the protecting device (1 ) by using tensile force,

f) attaching the second end (4) of the protecting device (1 ) to the flexible member (2) while the protecting device (1 ) is kept in stretched condition, after which the tensile force is removed, the said inside diameter of the protecting device (1 ) being greater than the outside diameter of the flexible member (2).

2. The method according to claim 1 , characterized in that the protecting device (1) has a variable inside diameter, preferably a periodically variable inside diameter.

3. The method according to claim 1 or 2, characterized in that the protecting device (1 ) is placed on the flexible member (2) using an intermediate cylindrical insert according to the following procedure: first, the insert is slid on the flexible member (2), then the protecting device (1 ) is slid the intermediate cylindrical insert and subsequently the intermediate cylindrical insert is removed, leaving the protecting device (1 ) on the flexible member (2).

4. The method according to any of the claims from 1 to 3, characterized in that the protecting device (1 ) is placed on the flexible member (2) by fastening the protecting device (1 ) and/or the flexible member (2) in an apparatus producing rotary motion, substantially coaxial with the protecting device (1) and/or the flexible member (2), and by gradually inserting the protecting device (1 ) on the flexible member (2) while retaining the rotary motion of the protecting device (1 ) and/or the flexible member (2).

5. The method according to claim 4, characterized in that the protecting device (1 ) rotates in the direction opposite to the rotation direction of the flexible member (2).

6. The method according to claim 5 characterized in that the rotational speed of the flexible member (2) is smaller than the rotational speed of the protecting device (1).

7. The method according to any of the claims from 1 to 6, characterized in that different values of force are used at step e), depending on the desired energy absorption characteristics.

8. The method according to any of the claims from 1 to 7, characterized in that the protecting device (1 ) is made of metal wire or of a material having hardness corresponding to hardness values between HRG and HRA in Rockwell scale.

9. The method according to any of the claims from 1 to 8, characterized in that the flexible member (2) comprises a braided rope, a stranded rope, an electric cable or a fluid conduit.

10. The method according to any of the claims from 1 to 9, characterized in that the procedure of attaching the first end (3) of the protecting device (1 ) and/or the second end (4) of the protecting device (1 ) to the flexible member (2) comprises threading the first end (3) of the protecting device (1) and/or the second end (4) of the protecting device (1 ) through the flexible member (2) or clamping an attachment element (5), preferably a hose clamp, a clamping ring, a clamping sleeve or a magnetic clamp.

11. The method according to claim 10, characterized in that the attachment elements (5) are additionally clamped around at least one intermediate region which is located between the first end (3) and the second end (4) of the protecting device (1 ), in the area where the protecting device (1 ) has the smallest inside diameter.

12. A flexible member with a shock absorber comprising a flexible member (2) and a spring- shaped protecting device (1 ) placed around it, the protecting device (1 ) being attached to the flexible member (2) on both sides of the flexible member (2), characterized in that the flexible member (2) is longer than the protecting device (1 ), the inside diameter of the protecting device (1 ) is greater than the outside diameter of the flexible member (2), and the flexible member (2) is compressed in such a manner that it gathers together and/or folds in the space created between the inside diameter of the protecting device (1 ) and the outside diameter of the flexible member (2), thus filling the said space.

13. The flexible member with a shock absorber according to claim 12, characterized in that the protecting device (1 ) has a variable inside diameter, preferably a periodically variable inside diameter.

14. The flexible member with a shock absorber according to claim 12 or 13, characterized in that the flexible member (2) comprises a braided rope, a stranded rope, an electric cable or a fluid conduit.

15. The flexible member with a shock absorber according to any of the claims from 12 to 14, characterized in that the protecting device (1 ) is made of metal wire or of a material having hardness corresponding to hardness values between HRG and HRA in Rockwell scale.

16. The flexible member with a shock absorber according to any of the claims from 12 to 15, characterized in that the procedure of attaching the first end (3) of the protecting device (1 ) and/or the second end (4) of the protecting device (1 ) to the flexible member (2) comprises threading the first end (3) and/or the second end (4) of the protecting device (1) through the flexible member (2) or clamping an attachment element (5), preferably a hose clamp, a clamping ring, a clamping sleeve or a magnetic clamp.

17. The flexible member with a shock absorber according to claim 16, characterized in that the attachment elements (5) are additionally clamped around at least one intermediate region which is located between the first end (3) and the second end (4) of the protecting device (1 ), in the area where the protecting device (1 ) has the smallest inside diameter.