JP2010515833A - Cable with low structural elongation - Google Patents

Abstract

  A cable (211) comprising a steel cord (212) and a polymer material (215) is provided. The steel filament (213) of the steel cord (212) is coated with an adhesive prior to infiltrating the polymer material (215). The cable (211) of the present invention has a structural elongation of less than 0.025% and an E module that is 4% larger than the E module of the steel cord (212). These two improvements further reduce overall cable elongation at specific loads.

Description

  The present invention relates to a cable. In particular, the present invention relates to a cable having limited elongation.

  Cables, particularly control cables, are widely used to transmit movement such as cables for window lift systems, scooters, bicycles, and cables used to open and close brakes on other vehicles. In these and many other applications, limited cable elongation is required.

  Cables are also widely used as tension members to reinforce polymer materials such as steel cords that reinforce radial tires, transmission belts, timing belts, or cables that reinforce flat belts for hoisting. These applications also require that the cable stretch be limited.

  In general, the tension curve of a prior art cable takes the form of a “hockey stick” curve as shown in FIG. During the initial elongation period, the cable is highly stretched, the tension is low, and the curve is relatively flat. In the final elongation period, the cable elongation is approximately linear with the cable tension as shown by line 120 in FIG. With increasing tension, cable elongation increases gradually. At this stage, the increase in cable elongation is proportional to the increase in cable tension, ie, Δε = Δδ / E, where Δε is the increase in cable elongation, Δδ is the increase in cable tension, and E Is a module of the cable. This is called elastic elongation. When the line 120 is extended until it intersects the horizontal axis, the intersection ε0 represents the structural elongation at low tensile stress of the cable. Therefore, the elongation of the cable at a certain tensile stress can be expressed as ε = ε0 + δ / E. From this equation, it can be seen that the elongation of the entire cable at a certain tensile stress includes two parts: structural elongation and elastic elongation.

  Thus, there are two ways to obtain a cable with limited elongation. One way is to reduce the structural elongation of the cable, and the other way is to increase the E module of the cable, as the increase in cable E module decreases the elongation under tension.

  In addition, the cable structure elongation ε0 is unstable because there are many factors that determine the cable structure elongation, such as the structure of the cable, the gap between the cable filaments, and the pre-tension of the filament during cabling. Unpredictable. Thus, the unstable and unpredictable behavior of the cable's structural elongation creates problems in predicting the overall cable elongation under tension, such as more breakdown during start-up of the machine that manufactures the precision timing belt. Occurs. Thus, by further reducing or eliminating the structural elongation ε0, predictability can be improved under cable tension and the manufacturing process can be facilitated.

  WO 03044267 discloses a cable having a limited elongation of less than 0.05% at a permanent force of 50 N after applying a force of 450 N. This improvement is achieved by a cord comprising a steel cord and a polymer material. This low elongation is highly related to the permeation of the polymer material into the steel cord, but there are limitations with respect to the penetration rate and pressure of the extrusion process.

  WO2005043003 discloses a thin steel cord having a low structural elongation. This low structural elongation is achieved by using a special cabling process. This special cabling process not only reduces the productivity of the cabling process, but also requires fine tuning which takes time to set the tension of the filament or strand.

  One object of the present invention is to eliminate the disadvantages of the prior art. It is also an object of the present invention to further limit cable elongation without complicating the manufacturing process of the cabling process.

  According to the present invention, a cable comprising a steel cord and a polymer material is provided. The steel filaments of the steel cord are coated with an adhesive before allowing the polymer material to penetrate. The cable of the present invention has a structural elongation of less than 0.025%. Furthermore, the E module of the cable of the present invention increases by over 4% over the E module of the bare steel cord. These two improvements further reduce overall cable elongation at specific loads.

  The cable as the subject of the present invention includes a steel cord, which includes several steel filaments.

The tensile strength of the steel filaments for the steel cord is preferably greater than 1700 N / mm ^2, or exceed 2200N / mm ^2, further more than 2600N / mm ^2, and most preferably greater than 3000N / mm ^2, more 4000N / more than mm ^2. The diameter of the filament is less than 400 μm, preferably less than 210 μm, most preferably less than 110 μm.

  All filaments can have the same diameter. In some cases, the filaments may have different diameters. Preferably, the diameter of the filaments forming the inner strands of the cable is greater than the diameter of the filaments used to form the outer strands or outer layers of the filaments into the cable, thereby penetrating the polymer material into the cable space. Is improved.

  Steel cords have an inner layer or core that is a strand of several steel filaments. Around such a core is provided at least one layer of additional steel elements. The steel elements of the additional layer can be either steel filaments or steel strands containing steel filaments. Various steel cord structures can be used.

Examples of the present invention include the following:
For example, an m × n type multi-strand steel cord, ie a steel cord containing m strands for each of n steel filaments, for example 4 × 7 × 0.10, 7 × 7 × 0.18, 8 × 7 × 0 .18, or 3 × 3 × 0.18; the last number is the diameter of the steel filament in units of mm;
A multi-strand steel cord comprising one core strand of c metal filaments and m strands of n steel filaments surrounding the core strand. These steel cords are hereinafter referred to as c + m × n type cords, for example 19 + 9 × 7 or 19 + 8 × 7 cords;
Warrington type steel cord;
For example, a 1 × n type compact cord, that is, a steel cord including n steel filaments, where n is greater than 8 and twisted in only one direction in one step, for example 1 × 9 × 0.18 Having a compact cross section; the last number is the diameter of the steel filament expressed in mm;
For example, a c + m (+ n) type layered steel cord, i.e. a steel cord in which a core of c filaments is surrounded by one layer of m filaments and possibly also by another layer of n filaments, e.g. 2 + 4 × 0.18; the last number is the diameter of the steel filament in units of mm.

  The steel composition of the steel cord is preferably a normal carbon steel composition, ie generally a minimum carbon content of 0.40% (eg at least 0.60%, or at least 0.80%, up to 1.1% ), The manganese content is in the range of 0.10 to 0.90%, the silicon content is in the range of 0.10 to 0.90%, and the sulfur and phosphorus contents are each preferably 0.03. %, And additional microalloying elements such as chromium (up to 0.2-0.4%), boron, cobalt, nickel, vanadium can be added to the composition, but the stainless steel composition is excluded It is not a thing. The steel filament and the steel cord are manufactured by a well-known conventional technique in which cable forming or bunching is performed after wet drawing.

After an optional cleaning operation, selected from organofunctional silanes, organofunctional titanates, and organofunctional zirconates that are well known in the art to improve adhesion between the steel cord and the polymeric material Coat the steel cord with adhesive. Preferably, but not exclusively, the organofunctional silane is selected from compounds of the formula:
Y- _{(CH 2)} N -SiX ₃
In the above formula,
Y represents the organic functional group selected from —NH ₂ , CH ₂ ═CH—, CH ₂ ═C (CH ₃ ) COO—, 2,3-epoxypropoxy, HS—, and Cl—
X represents a silicon functional group selected from —OR, —OC (═O) R ′, —Cl, wherein R and R ′ are independently selected from C1-C4 alkyl, preferably —CH ₃ , and — C ₂ H ₅ ;
n is an integer between 0 and 10, preferably between 0 and 3.

  In addition to the aforementioned organofunctional silanes, there are other steel PU adhesives that are commercially available. They are marketed under the names Chemosil (manufactured by the German company Henkel) and Chemlock (manufactured by Lord Corporation).

  The polymeric material used in the present invention may be any elastomeric material that can be conveniently applied to steel cords with sufficient adhesion. More preferably, a thermoplastic elastomer (TPE) can be used. Non-limiting examples are polystyrene / elastomer block copolymers, polyurethane (PU) or polyurethane copolymers, polyamide / elastomer block copolymers, thermoplastic vulcanizates. Preferably, thermoplastic polyurethane is used. Homopolymers of esters, ethers or carbonate polyurethanes, as well as copolymers or polymer blends can be used. Preferably, the polymeric material has a Shore hardness between 30A and 90D.

  The polymer penetration of the inventive subject cable is greater than 70%, preferably greater than 90%. The steel cord used to obtain the subject cable of the present invention includes several steel filaments that are transformed into a steel cord using a steel cord structure. Due to this steel cord structure, a space is formed between the steel filaments of the steel elements of the cord. A space is also formed between the steel elements. As used herein below, “space” should be understood as the entire area of the radial cross section of the cord located inside the imaginary circle surrounding the radial cross section of the steel cord that is not occupied by the steel. It is. Thus, the polymer permeability of the cable of the present invention is defined as the percentage ratio of the space filled with polymer to the space not occupied by steel.

  The thickness of the polymer coating of the present invention is less than 100 μm, preferably less than 10 μm. The optical diameter of the steel cord used to obtain the cable of the present inventive subject matter is the diameter of the smallest virtual circle that surrounds the radial cross section of the steel cord. The optical diameter of the cable of the present invention is the diameter of the smallest virtual circle that encloses the radial cross section of the cable. Thus, the thickness of the polymer is defined as half the difference in optical diameter between the cable and the steel cord.

  The present invention will now be described in more detail with reference to the accompanying drawings.

It is an example of the tension curve of the cable of a prior art. 1 is an example of a cross-sectional view of a cable embodying the present invention. It is an example of the tension curve of the cable which embodies the present invention.

  FIG. 1 shows a tension curve 110 for a prior art cable, and line 120 shows the E module of the cable. Line 120 extends to the horizontal axis and intersects at intersection ε0, which represents the structural elongation at low tensile stress of the cable.

  There is a cross-sectional view of a cable embodying the present invention as shown in FIG. The cable 211 includes one steel cord 212, which includes several steel filaments 213. This embodiment shows a steel cord with a “7 × 7 × d” structure having seven strands 219, each strand having seven steel filaments 213 of diameter dmm. This steel cord has an optical cord diameter 214. This steel cord is coated with a polymeric material 215, thereby providing a cable 211 as the subject of the present invention having an optical cable diameter 216. The polymer coating thickness 217 is half of the difference between the optical cord diameter and the optical cable diameter. As shown in FIG. 2, the space 218 between the different steel filaments 213 is preferably substantially filled with the polymer material 215.

  In FIG. 3, a cable tension curve 310 embodying the present invention is shown, and line 320 shows the E module of the cable. Line 320 extends to the horizontal axis and intersects at intersection ε0, which represents the structural elongation at low tensile stress of the cable.

  In the following table, a comparative test between a prior art cable and a cable embodying the present invention is shown. This test is performed on a Zwick-Z020 testing machine according to ISO test method ISO RA-30-203. After a single test is completed, the testing machine can automatically provide the following test results and tensile curves for the specimen.

Comparative test 1:
Prior art: 1 × 3 + 5 × 7 × 0.15 steel cord;
The present invention: 1 × 3 + 5 × 7 × 0.15 steel cord with adhesive treatment and PU coating.

  This test result shows that the present invention not only substantially reduced the structural elongation of the cable by 74%, but also improved the E module of the cable by 9.6%. These two improvements substantially improve the elongation at a specific load, reducing the overall elongation at 50N by 52%. In addition, the tensile curves in FIGS. 1 and 3 also show this improvement.

Comparative test 2:
Prior art 1: 7 × 3 × 0.15 steel cord;
Prior Art 2: 7 × 3 × 0.15 steel cord with PU coating;
The present invention: 7 × 3 × 0.15 steel cord with adhesive treatment and PU coating.

  The test results show that not only the cable structural elongation was substantially reduced by 91%, but the cable E-module was also improved by 4%. These two improvements substantially improve the elongation at a specific load, reducing the overall elongation at 50 N by 35%. In addition, the tensile curves in FIGS. 1 and 3 also show this improvement.

  Compared to the prior art, the use of an adhesive on the surface of the steel filament prior to application of the polymer material further improves the fixation of the steel filament inside the polymer material. The steel filaments of the steel cord are prevented from slipping and rotating even in some spaces that are not filled with polymer material, thereby further limiting the structural elongation of the cable. Furthermore, the improved fixation of the steel filament inside the polymer material also improves the E module of the cable because no slipping or peeling occurs between the steel filament and the polymer material.

  A further improvement of the invention is characterized by the thickness of the cable's polymer coating. A cable with only 10 μm polymer coating only slightly increases the cable diameter, which is particularly beneficial in the case of cables used as tension members to reinforce toothed belts. The toothed belt is molded in a semi-open mold, where the polymer material is poured into the mold or extruded at low pressure so that the polymer material inside the mold flows between the tension members. Is limited, and finally required shapes (toothed, flat, smooth, etc.) are formed. Thus, a thin cable having a polymer coating of less than 10 μm leaves more space for the polymer material to flow inside the mold to form a flat and smooth belt.

  Another use of this thin cable with a polymer coating of less than 10 μm is for window lift systems. Cables used in window lift systems must be clamped with metal nipples at the cable ends to connect to other parts, so for cables with thick polymer coatings, a secure connection between the cable ends and the nipple Cannot be guaranteed. The nipple is clamped on the polymer coating, which transmits its tension to the inner steel cord. Since the tensile strength of the polymer material is much lower than the tensile strength of the steel cord, the connection between the cable and the nipple is broken at low loads, and the load carrying capacity of the cable is gradually reduced due to this weakness. When a cable with a polymer coating of less than 10 μm is used in a window lifting system, the metal nipple is fastened directly to the steel cord because the thin coating of polymer material is deformed. Such an application ensures a connection between the cable and the nipple and eliminates the weaknesses of this system. Furthermore, if the coating thickness is less than 10 μm, or even 0 μm, the cable from the outside is substantially the same as a bare cable and has the same friction and wear characteristics. This can be very convenient if one wants to use such a product instead of a bare cable in a cable system, since no replacement of guide parts, cable tubes, etc. is required.

  Another improvement of the present invention is the use of the inventive subject cable in the manufacture of multi-strand ropes for winding applications such as elevator ropes. First, the elevator industry is looking for ropes with limited elongation. Since the strands of the present invention have a limited elongation, the rope also has a limited elongation. Therefore, an elevator rope using the present invention satisfies this requirement. Second, the elevator industry is looking for ropes that can be used with small pulley diameters. Standard elevators use ropes with a generally accepted ratio of pulley diameter “d” to rope diameter “D” of 40. The fatigue life of the rope is greatly reduced when all conventional steel ropes are used under the condition that the d / D ratio is less than 40. One cause of rope breakage under these conditions is excessive fretting between strands and wires. The polymer coating on the rope can reduce fretting and improve the fatigue life of the rope, but a thick polymer coating is required to ensure a durable polymer sheath, which increases the diameter of the rope. The present invention solves this dilemma. On the one hand, steel strands are coated with polymer to reduce fretting. On the other hand, the adhesive treatment improves the connection between the steel and the polymer and allows for a thin coating. Therefore, the rope made from the cable of the present invention is suitable for winding applications.

Item 110 is the tensile curve of the prior art cable;
Item 120 is a line indicating the E module of the prior art cable;
Item 211 is a cable embodying the present invention;
Item 212 is a steel cord for a cable embodying the present invention;
Item 213 is a steel filament for a cable embodying the present invention;
Item 214 is the optical diameter of the steel cord for the cable embodying the present invention;
Item 215 is a polymer material used in a cable embodying the present invention;
Item 216 is the optical diameter of the cable embodying the present invention;
Item 217 is the thickness of the cable polymer coating that embodies the invention;
Item 218 is the space in the cable embodying the present invention;
Item 219 is a steel strand for a cable embodying the present invention;
Item 310 is the tensile curve of the cable embodying the present invention;
Item 320 is a line indicating the E module of the cable embodying the present invention;
ε0 is the structural elongation of the cable;
F (N) is the force on the specimen in Newton units;
E (%) is the elongation of the specimen in percent.

Claims (9)

  A cable comprising a steel cord and a polymer material, characterized in that the structural elongation of the cable is less than 0.025%.   Cable according to claim 1, characterized in that the E module of the cable is 4% larger than the E module of the steel cord.   Cable according to any one of claims 1 and 2, characterized in that the polymer filling rate exceeds 70%.   4. Cable according to claim 3, characterized in that the polymer filling rate exceeds 90%.   Cable according to any one of claims 1 to 4, characterized in that the polymer coating has a thickness of less than 100 m.   Cable according to claim 5, characterized in that the polymer coating has a thickness of less than 10 m.   Cable according to any one of the preceding claims, characterized in that the polymer material is a thermoplastic polymer.   The cable according to claim 7, wherein the thermoplastic polymer is polyurethane.   A rope comprising at least one cable according to any one of the preceding claims.

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