WO2009052950A1

WO2009052950A1 - Retarding device

Info

Publication number: WO2009052950A1
Application number: PCT/EP2008/008493
Authority: WO
Inventors: Hans Peter Von Allmen
Original assignee: Geobrugg Ag
Priority date: 2007-10-18
Filing date: 2008-10-08
Publication date: 2009-04-30
Also published as: EP2201177A1; CH701591B1

Abstract

The retarding device (1) for absorbing kinetic energy, which occurs in a control structure for protecting against falling masses, in particular against rock falls and avalanches, under dynamic loading, comprises at least one absorption element (2) which is arranged to be retained between two retaining ends (15, 16) and by means of which energy can be absorbed through tension (Z) at the retaining ends. The absorption element (2) extends substantially straight when it absorbs energy so as to absorb the energy by being extended by the tension and becoming thinner in the process.

Description

braking device

The present invention relates to a braking device for absorbing kinetic energy according to the preamble of claim 1.

Such braking devices are e.g. built into restraint and suspension ropes of flexible structures against stone and ice. The networks spanned between ropes catch rocks and ice masses that collapse and bring them to a standstill. The kinetic energy of the rock and ice masses is absorbed by the braking devices ("energy absorber", "energy dissipator").

Most known braking devices currently in use (see, for example, EP 0 494 046 A1, DE 10 2005 053 704 A1, DE 10 2005 053 710 A1 or CH 610 631 A5) function predominantly as friction brakes, by transmitting at least part of the energy via frictional forces dismantle. The corresponding force-displacement diagrams are characterized by an unstable braking force over the length of the braking distance with a sharp increase or decrease of the braking force towards the end of the braking distance. As a result, the energy over the length of the braking distance is not evenly reduced. In addition, braking forces lead over the length of the braking distance peaks have to uneconomic anchorages in the ground, as they must be designed for the highest braking forces occurring.

From EP 1 469 130 A1 a brake device is known, which has an absorption element in the form of a spiral, which is formed from a helically curved profile. The energy absorption occurs predominantly in the form of plastic deformation work by stretching the turns of the spiral. In order for the kinetic energy of the spiral to be able to be absorbed, which may typically be more than 10 kJ and even more than 50 kJ, the absorption element must consist of a large mass. Heavy braking devices, however, are difficult to assemble, since constructions are often in rough terrain. Furthermore, even before the break, the spiral exhibits a sharp increase in the braking force, which brings with it the above-mentioned disadvantage with regard to the design of the anchoring.

The object of the present invention is to provide a brake device which has a lighter construction and is interpretable so that it has a better force-displacement behavior.

A braking device which achieves this object is specified in claim 1. The further claims indicate preferred embodiments of the braking device according to the invention.

By providing at least one absorption element, by means of which the energy is absorbable by being stretched by stretching and thereby becoming thinner, the expansion capacity of the material itself can be utilized. It is thus also with a relatively light braking device, a large energy absorbable. The braking device is designed so that in the tensile stress peaks in the braking forces are avoided.

The invention will be further explained by embodiments with reference to figures. Show it:

1 shows a first embodiment of an inventive braking device with simple loop ends in a side view. FIG. 2 shows the braking device from FIG. 1 in a plan view; FIG.

3 shows a second Ausführungsbetspiel a brake device according to the invention with cased loop ends. 4 shows a third exemplary embodiment of a braking device according to the invention with loops of different lengths; 5 shows a fourth exemplary embodiment of a braking device according to the invention made of straight wires with compression heads and with anchor bodies for attachment to the cable;

FIG. 6 shows the brake device from FIG. 5 from the front; FIG. 7 shows a fifth embodiment of a brake device according to the invention with press sleeves as a connection to the cable;

8 shows a section of the brake device from FIG. 7 through the compression sleeve; FIG.

9 is a typical force-displacement diagram of a brake device according to the invention; Fig. 10 is a typical stress-strain diagram of a preferred material for a brake device according to the invention, and

Fig. 11 shows a construction with inventive braking devices.

Fig. 1 shows a braking device 1, comprising a wire 4, which is several times between two opposite reversal points 8, at which it is bent back in each case by 180 °, to loops is wound back and forth. The beginning of the wire 4 and the end of the wire 4 are e.g. connected by a weld.

As shown in FIG. 2, the loops of the wire 4 are arranged parallel next to one another.

The reversal points 8 form ends for holding the brake device 1. This is connected during assembly by means of shackles 7 with ropes by the bolt 8 of the shackle 7 is inserted through the respective holding end. The diameter of the bolt can be increased if necessary by attaching a hollow cylinder to reduce the bending and transverse forces at the holding ends 8 of the wire 4.

The straight parts of the wire 4 between the reversal points 8 form elongated absorption elements 2, which extend substantially parallel to the tensile force Z, which acts on the braking device 1 in the event of loading. In the tensile stress, the wires 4 of the absorption elements 2 are stretched elastically and predominantly plastically to break, while reducing their cross-section. The energy is thus absorbed by pure material deformation, in particular without unstable adhesive and sliding friction forces on contact surfaces.

FIG. 3 shows a brake device 1 which comprises a plurality of loops, which are respectively guided at the holding ends 8 through a pipe 9. The cavity between the tube 9 and extending in the pipe 9 sections of the wire 4 is filled with a backfilling 10, which connects the wire sections frictionally with the tube 9. As available - A -

ment 10 is suitable e.g. a water-cement mixture with any additives or a plastic-based mortar.

The length of the tube 9 can be chosen so that each individual wire section and the wire beginning 5 and the wire end 6 are anchored in the pipe 9 to their breaking load. As a result, in extreme cases, the absorption elements 2 of all loops are claimed until complete exhaustion of their elasticity, whereby for the material in question a maximum utilization of its capacity for energy absorption is achieved. At the same time, the filled tube 9 prevents a reduction in the tensile strength of the wire 4 in the region of the reversal point 8 as a result of additional stresses such as local transverse pressure and bending stresses.

In the following, a concrete embodiment of a braking device 1 according to FIG. 3 is described, which has an approximately constant over the braking distance braking force (force for stretching the absorption elements 2) of about 100 kN and a braking distance of about 1 m and thus an energy of about 100 kJ can absorb.

The braking device comprises six loops of a wire 4 with a diameter of 4 mm and of the material with the number EN 1.4307 according to European standard or with the number AISI 304 L according to the standard of the "American Iron and Steel Institute". This material has a tensile strength of about 650 N / mm ² and an elongation at break of about 42.5%.

The tubes 9 each consist of a steel tube with an outer diameter of 26.9 mm, a wall thickness of 2.6 mm, which is made of the material no. EN 1.4301 (AISI 304) and has a developed length of 500 mm.

Backfilling 10 comprises a cement-water mixture with additives (propellant, plasticizer and setting accelerator).

The initial length of the braking device 1 between the exit of the wires from the casing 9 corresponds to the initial length of the absorption elements 2 and is about 2.50 m. The total length L _{0 of} the brake device 1 in the initial state is about 2.90 m, the total length L _E in the fracture state is about 4.00 m. The braking device weighs a total of about 6.0 kg.

4 shows a variant of the braking device according to FIG. 3 in that a plurality of loops are provided, which have an increasing length, whereby the absorption 2 elements are claimed staggered by first the shortest absorption elements 2 to break and then the next longer absorption elements 2 are further stretched and stretched to break. As a result, the brake force curve, ie the braking force, can be controlled as a function of the braking distance in accordance with specific requirements.

Fig. 5 shows a braking device comprising a plurality of absorption elements 2 in the form of wires, which are each provided at its two ends for anchoring in an anchor body 15 with upset heads 16. These are e.g. produced by the method of Birkenmaier, Brandestini and Ros, in which the upsetting of the wire in the cold state is done with a compression machine.

The respective anchor body 15 comprises two parts, between which the cable 17 is clamped, which is subjected to a train Z in the load case. The rope 17 is e.g. a carrying or restraining rope or another force-transmitting rope in a Verbauung and has between the two anchor bodies 15 has a length corresponding to the maximum braking distance of the brake device 1, so that at the end of the braking distance, the cable 17 is stretched and can take over the upcoming force.

The respective anchor body 15 has continuous longitudinal bores through which the wires 2 extend, as well as through transverse bores for receiving screw connections 3 to form a detachable connection.

As shown in FIG. 6, four wires are provided, which are anchored by means of the compression head 16 on the anchored to the cable 17 anchor body 15. The wires 2 are arranged symmetrically about the cable 17 and thus about the direction of the tensile force Z, when it acts. The symmetrical arrangement ensures that the extensibility of the wires 2 is completely exhausted and, in particular, in the transition from the anchor body 15 to the free length of the wires 2 no additional stresses such. Transverse forces can arise that lead to premature breakage.

In the following, a concrete embodiment of a braking device 1 according to FIG. 5 is described, which has an approximately constant over the braking distance braking force of about 100 kN and a braking distance of about 1 m and thus can absorb an energy of about 100 kJ. The braking device 1 comprises four wires 2, each with a diameter of 7 mm, which are made of the material no. EN 1.4307 (AISI 304 L), and are provided on both sides with upset heads 16 which are anchored in the anchor bodies 15.

The output length of the brake device 1 between the upset heads 16 of the wires 2 is about 2.50 m, the total length L ₀ = 2.52 m, the length in the broken state L _E = 3.55 m. The wires 2 without the anchor body 15 weigh about 3.0 kg.

A variant of the braking device according to FIG. 5 can also have wires of increasing length, which form absorption elements 2, which are claimed staggered by first breaking the shortest absorption elements 2 and subsequently further stretching the next longer absorption elements 2 and stretching them to breakage become.

A further variant of the braking device according to FIG. 5 may also comprise one-piece anchor body 15, which are suitable for receiving a towing device. For example, it may be provided a cylindrical anchor body which is provided with an external thread for fastening a ring nut, or a cuboid anchor body which is provided with a bore for receiving a shackle.

Fig. 7 shows a braking device comprising a plurality of absorption elements 2 in the form of parallel wires, the ends of which are connected directly to the cable 17 or a cable assembly by means of a compression sleeve 22. The cable 17 has a length between the two press sleeves 22, which corresponds to the maximum braking distance of the brake device 1, so that at the end of the braking distance, the cable 17 is stretched and can take over the pending force.

As the section through the compression sleeve 22 with the compressed cable 17 in FIG. 8 shows, the wires 2 are arranged symmetrically around the cable 17 so that tilting of the compression sleeve 22 and thereby caused additional stresses on the wires 2 are avoided as far as possible during tensile stressing and the break is caused by constriction on the free length of the wires 2.

In an alternative form, a strand in the form of wires stranded with one another is used as the absorption element 2, the ends of which are fastened to the cable 17 by means of press sleeves 22 analogously to the example according to FIG.

In the following, a concrete embodiment of a brake device 1 according to FIG. 7 is described, which has an approximately constant over the braking distance - 1 -

Braking force of about 100 kN and a braking distance of about 1 m and thus can absorb an energy of about 100 kJ.

The braking device 1 comprises twelve wires, each with a diameter of 4 mm, which are made of the material no. EN 1.4307 (AISI 304 L) and are connected on both sides by means of press sleeves 22 with the cable 17.

The initial length of the braking device 1 between the press sleeves 22 corresponds to the initial length of the absorption elements 2 and is about 2.50 m, the total length L ₀ = 2.70 m, the length in the broken state L _E = 3.75 m. The wires 2 without the ferrules 22 weigh about 3.25 kg.

To absorb the kinetic energy, the elastic and predominantly plastic extensibility of the absorption elements 2 is exhausted by tensile stress. By taking advantage of the absorption capacity of the material directly, the braking device 1 can be manufactured with a relatively low weight, which u.a. also facilitates assembly in a housing much easier.

Since the expansion behavior of the material is directly reflected in the expansion behavior of the braking device 1, this can be easily adapted to the desired requirements by a material with the desired properties is selected. Among other things, it is possible to provide an almost ideal braking device which generates over the length of the braking distance an at least approximately constant braking force and thus reduces the resulting energy evenly. Advantageously, a material is used whose stress-strain diagram has a value of the plastic strain R _p i which is high in relation to the tensile strength R _m . _o and has a horizontal as possible curve of the stress-strain curve in the plastic region (for the meaning of R _m and R _{p1 0} see below).

Fig. 9 shows a typical braking force 12 - braking distance 13 - diagram of the braking device 1 with almost ideal braking force curve 11. As can be seen, the braking force 12 increases sharply at the onset of braking effect and then remains at a nearly constant value before it comes to break (in Fig. 9 indicated by the dashed line). The area 14 under the curve corresponds to the absorbed energy. Typically, with the braking device 1, a kinetic energy of at least 10 kJ, preferably of at least 20 kJ and particularly preferably of at least 50 kJ absorbable.

With a suitable choice of units, the braking force-Bremsweg diagram with respect to the shape of the curve 11 is congruent with the stress-strain diagram of used material. Fig. 10 shows a typical stress-strain diagram of a material made of corrosion-resistant steel. The ordinate 18 corresponds to the stress in N / mm ² (applied force divided by the area of the initial cross section) and the abscissa 19 of the elongation in percent (ratio of the length change to the initial length in percent). The material has an elastic behavior with a small elongation 19 and then begins to flow with increasing elongation and thus plastically, ie to permanently deform.

In Fig. 10, 20 denotes the value R _p i ₀ , which indicates the stress which causes a plastic strain of 1% in the material. The value R _p io results from the stress-strain diagram, in which the ascending straight line passing through the zero point is shifted in parallel by the distance of 1%.

In Fig. 10, 21 denotes the value R _m indicating the tensile strength in N / mm ² . This corresponds to the tension resulting from the maximum tensile force related to the initial cross-section.

A behavior of the braking device 1 according to FIGS. 9 and 10 has the advantage that the braking force 12 is essentially independent of the braking distance 13 and remains approximately constant. The energy is thus reduced evenly. Let F _{p1 0} and F _m denote the braking force, which in the stress-strain diagram of the stress at the limit of plastic strain, R _p i. _o , or corresponding to the value of the tensile strength R _m , the braking force, after it has reached F _{p1 0} , deviates from the mean value of F _{p1 0} and F _m by at most ± 20% and preferably at most ± 15%. Accordingly, the voltage curve of the voltage 18 from the value R _p i _{0 is} such that the voltage 18 from the average of R _p1 . ₀ and R _m deviates by at most ± 20% and preferably at most ± 15%.

The braking device 1 is connected to an anchoring in use in a building. This is designed for the maximum occurring braking force. Due to the approximately constant brake force curve 11 peaks in the braking force 12, as they occur in the usual braking devices avoided. Thus, weaker anchors than usual are sufficient to anchor the brake device 1.

Materials which can be used for the absorption elements 2 and exhibit a behavior according to FIG. 10 have a tensile strength of at least 200 N / mm ² , preferably of at least 400 N / mm ² and more preferably of at least 500 N / mm ^2, and an elasticity (Elongation at break) of at least 20%, preferably at least 30% and more preferably at least 40%. A group of materials in which to find materials meeting such requirements includes steel, preferably stainless steel such as. For example, the steel with the material number EN 1.4307 (AISI 304 L), which has the following data: tensile strength R _m of about 650 N / mm ² , R _{p1 0} of about 490 N / mm ² and elongation at break of about 42.5 %.

In addition to materials made of steel, in particular corrosion-resistant steel (with chromium and nickel as main alloying elements), it is also possible to use other metallic materials which have a sufficiently high strength and a pronounced elasticity. Such materials may also be outside the group of predominantly ferrous materials.

According to the embodiment of the braking device 1, a kinetic energy of at least 1 kJ, preferably of at least 20 kJ and particularly preferably of at least 50 kJ is absorbable. Typically, the braking distance (length at break minus the initial length) is one decimeter to several meters and the braking force is at least 5 kN, preferably at least 20 kN. This can be 200 kN or even more.

The braking devices according to the invention can be used in anti-rock and icing constructions or in other structures for protection against falling masses.

11 shows an example of such a construction with a safety net 30, which is stretched on its two longitudinal sides on supporting cables 31, and with supports 32, on which the supporting cables 31 are held and which are anchored via retaining cables 33 to anchors 34. The safety net 30 is only indicated in FIG. 11 and is not completely drawn. The support cables 31 are attached to the anchors 35 via braking devices 1.

There may also be provided braking devices 1 integrated with the restraining cords 33, e.g. with deflectable supports 32 to be able to absorb energy, and / or which are connected to the safety net 30.

The connection of the braking devices 1 to the force-transmitting ropes 31 is carried out according to the construction of the braking device 1 by hanging the holding ends 8 by means of shackles 7, by clamping by means of anchor body 15 or by direct compression by means of compression sleeves 22nd

If the brake devices 1 are constructed according to the first, second or third exemplary embodiment, advantageously a bypass cable 36 is suspended on the shackles 7. This ensures holding of the support cable 31 to the anchor 35, even if after a load case, the brake device 1 has been claimed to break. In the braking devices 1 according to the fourth and fifth embodiments, the carrying cable 31 is guided through the braking device 1, so that no bypass cable 36 is required.

When impacting stones, ice sheets or the like, the net 30 and the support cables 31 are set in motion. By this dynamic stress, the braking devices 1 are stretched by train Z and thereby reduce the kinetic energy.

Based on the foregoing description of preferred embodiments, modifications adapted to those skilled in the art are obtainable without departing from the scope of the invention as defined in the claims.

In order to reduce the initial length of the braking device, loops of different length can be connected to one another in the first or second embodiment of the braking device in such a way that they can be subjected to uninterrupted successive action.

Further, the braking device may comprise absorbing elements in the form of at least one loop of a round rod (for example of diameter> 10 mm) or of a rod of non-round cross-section, the rod beginning and the rod end being connected by means of screw socket or welding.

As absorption element, various embodiments are conceivable, e.g. Wire, rod, strand, bundles of parallel or stranded wires, e.g. Round wires with a diameter of 1 to 10 mm, or another elongated part. The absorption element may have a solid or hollow profile and be rectangular, square, oval, etc. in cross section.

The absorption elements may also be formed as wires which are stranded into a strand or a rope, at the ends of which loops are formed by means of press sleeves. Reference numerals:

1 brake device

2 absorption element

3 screw connection

4 wires

5 wire start

6 wire ends

7 shackles

8 stops

9 pipe

10 backfilling

1 1 braking force curve

12 braking force [kN]

13 braking distance [m]

14 area under the curve 11

15 anchor body

16 compression heads

17 rope

18 voltage [N / mm ² ]

19 elongation [%]

20 R _p1 o Stress [N / mm ² ] at 1% plastic strain

21 R _m tensile strength [N / mm ² ]

22 compression sleeve

30 safety net

31 carrying rope

32 support

33 retaining rope

34 anchorage

35 anchoring

36 bypass rope

Claims

claims

1. Braking device (1) for absorbing kinetic energy, which occurs in a structure for protection against falling masses, especially against rock and avalanches, under dynamic stress, with at least one absorption element (2), which between two holding ends (8 ; 9, 15, 16, 22) is arranged to be held and by which energy is absorbable by traction (Z) at the holding ends, characterized in that the absorbing element (2), when absorbing energy, is substantially straight running around the To absorb energy by being stretched by the train and becoming thinner.

2. Braking device (1) according to claim 1, which has a plurality of absorption elements (2), wherein the respective absorption element is substantially parallel to the direction of the train (Z), when it absorbs energy.

3. Braking device (1) according to one of the preceding claims, by means of which a kinetic energy of at least 1 kJ, preferably at least 20 kJ and particularly preferably of at least 50 kJ is absorbable.

4. Braking device (1) according to one of the preceding claims, wherein the at least one absorption element (2) is made of a material having a tensile strength (R _m ) of at least 200 N / mm ² , preferably of at least 400 N / mm ² and more preferably of at least 500 N / mm ²

5. Braking device (1) according to one of the preceding claims, wherein the at least one absorption element (2) is made of a material which has a Dehnvermo- gene of at least 20%, preferably of at least 30% and particularly preferably of at least 40%

6. Braking device (1) according to one of the preceding claims, wherein the at least one absorption element (2) is made of a material in which a plastic strain of 1% causes a voltage R _{p1 0} and which has a tensile strength R _m , wherein R _{p1 0th} and R _m deviates from the mean of R _{p1 0} and R _{m is} at most ± 20% and preferably at most ± 15%

7. Braking device (1) according to one of the preceding claims, wherein the at least one absorption element (2) made of steel, preferably of corrosion-resistant steel, or of a metallic material which is outside the group of predominantly ferrous materials

8. Braking device (1) according to one of the preceding claims, which has loops for forming a plurality of absorption elements (2)

A brake device (1) according to claim 8, wherein the loops are formed by winding a wire (4) back and forth several times between two opposite turning points (8)

10. Brake device (1) according to claim 8 or 9, wherein the loops have an increasing length so that they are claimed in succession in the energy absorption

Braking device (1) according to one of the preceding claims, which comprises the formation of the retaining end tubes (9) through which a plurality of absorption elements (2) are guided, which are by means of Vervollung (10) in frictional connection with the tubes

12. Braking device (1) according to one of the preceding claims, wherein the at least one absorption element (2) is a wire which is provided at its two ends to form the holding ends, each with a compression head (16).

13. Braking device (1) according to any one of the preceding claims, wherein the at least one absorption element (2) at the two ends (16) is held in each case on an anchor body (15) which can be fastened by means of releasable connection to a cable (17).

14. Braking device (1) according to one of the preceding claims, which has at least one compression sleeve (22) for forming the holding ends, by means of which the at least one absorption element (2) is pressed non-positively with a cable (17).

15. Braking device (1) according to one of the preceding claims, which sorption absorption elements in the form of stranded wires (2), which form a cable assembly having at both ends by means of press sleeves (22) pressed-on attachment loops.

16. Braking device (1) according to any one of the preceding claims, wherein the at least one absorption element (2) has a solid or hollow profile and / or is formed by a wire, a rod, a strand, a bundle of parallel or stranded wires or another oblong part.

17. Braking device (1) according to one of the preceding claims, which has several absorption elements (2), which are in at least one of the following

Distinguish characteristics: initial length, initial cross-section, tensile strength, elasticity.

18. Brake device (1) according to one of the preceding claims, wherein the holding ends (15; 22) are fastened to a cable (17) whose length between the holding ends is greater than the initial length of the at least one absorption element (2) between the holding ends.

19. Braking device (1) according to one of the preceding claims, wherein the maximum braking force (12) is at least 5 kN, preferably at least 20 kN and more preferably at least 50 kN.