EP0627520A1 - Compact steel cord with no wrapping filament - Google Patents
Compact steel cord with no wrapping filament Download PDFInfo
- Publication number
- EP0627520A1 EP0627520A1 EP94201134A EP94201134A EP0627520A1 EP 0627520 A1 EP0627520 A1 EP 0627520A1 EP 94201134 A EP94201134 A EP 94201134A EP 94201134 A EP94201134 A EP 94201134A EP 0627520 A1 EP0627520 A1 EP 0627520A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- filaments
- steel cord
- centre
- outer layer
- cord according
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 116
- 239000010959 steel Substances 0.000 title claims abstract description 116
- 230000002787 reinforcement Effects 0.000 claims abstract description 5
- 239000000314 lubricant Substances 0.000 claims description 4
- 238000010276 construction Methods 0.000 description 9
- 229920001971 elastomer Polymers 0.000 description 5
- 229910001369 Brass Inorganic materials 0.000 description 4
- 239000010951 brass Substances 0.000 description 4
- 239000010949 copper Substances 0.000 description 4
- 229910052802 copper Inorganic materials 0.000 description 4
- 239000000806 elastomer Substances 0.000 description 4
- 238000000034 method Methods 0.000 description 3
- 241001589086 Bellapiscis medius Species 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 210000003963 intermediate filament Anatomy 0.000 description 2
- 230000001788 irregular Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000011144 upstream manufacturing Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 229910000881 Cu alloy Inorganic materials 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 239000005864 Sulphur Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 230000001186 cumulative effect Effects 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- BHEPBYXIRTUNPN-UHFFFAOYSA-N hydridophosphorus(.) (triplet) Chemical compound [PH] BHEPBYXIRTUNPN-UHFFFAOYSA-N 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000011572 manganese Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 238000003892 spreading Methods 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- D—TEXTILES; PAPER
- D07—ROPES; CABLES OTHER THAN ELECTRIC
- D07B—ROPES OR CABLES IN GENERAL
- D07B1/00—Constructional features of ropes or cables
- D07B1/06—Ropes or cables built-up from metal wires, e.g. of section wires around a hemp core
- D07B1/0606—Reinforcing cords for rubber or plastic articles
- D07B1/0646—Reinforcing cords for rubber or plastic articles comprising longitudinally preformed wires
-
- D—TEXTILES; PAPER
- D07—ROPES; CABLES OTHER THAN ELECTRIC
- D07B—ROPES OR CABLES IN GENERAL
- D07B1/00—Constructional features of ropes or cables
- D07B1/06—Ropes or cables built-up from metal wires, e.g. of section wires around a hemp core
- D07B1/0606—Reinforcing cords for rubber or plastic articles
- D07B1/062—Reinforcing cords for rubber or plastic articles the reinforcing cords being characterised by the strand configuration
- D07B1/0626—Reinforcing cords for rubber or plastic articles the reinforcing cords being characterised by the strand configuration the reinforcing cords consisting of three core wires or filaments and at least one layer of outer wires or filaments, i.e. a 3+N configuration
-
- D—TEXTILES; PAPER
- D07—ROPES; CABLES OTHER THAN ELECTRIC
- D07B—ROPES OR CABLES IN GENERAL
- D07B2201/00—Ropes or cables
- D07B2201/20—Rope or cable components
- D07B2201/2015—Strands
- D07B2201/2024—Strands twisted
- D07B2201/2027—Compact winding
- D07B2201/2028—Compact winding having the same lay direction and lay pitch
-
- D—TEXTILES; PAPER
- D07—ROPES; CABLES OTHER THAN ELECTRIC
- D07B—ROPES OR CABLES IN GENERAL
- D07B2207/00—Rope or cable making machines
- D07B2207/20—Type of machine
- D07B2207/204—Double twist winding
- D07B2207/206—Double twist winding with means for providing less than double twist, e.g. counter rotating means
-
- D—TEXTILES; PAPER
- D07—ROPES; CABLES OTHER THAN ELECTRIC
- D07B—ROPES OR CABLES IN GENERAL
- D07B5/00—Making ropes or cables from special materials or of particular form
- D07B5/12—Making ropes or cables from special materials or of particular form of low twist or low tension by processes comprising setting or straightening treatments
Definitions
- the present invention relates to a steel cord adapted for the reinforcement of elastomeric articles such as the carcass plies and breaker plies of pneumatic radial tyres, conveyor belts, hoses and timing belts.
- a steel cord adapted for the reinforcement of elastomeric articles.
- the steel cord comprises a centre structure of one to five centre filaments and a maximum of two layers of layer filaments surrounding said centre : an outer layer of outer layer filaments and, possibly, one or more intermediate layers of intermediate layer filaments between the centre structure and the outer layer. All the centre filaments and all the layer filaments have the same twist hand and the same twist pitch.
- the outer layer filaments exert a force which is directed radially inward and which is of such a magnitude that sleeving of the steel cord is prevented.
- a steel cord "adapted for use in the reinforcement of elastomeric articles” means that the steel cord has the necessary features to reinforce elastomeric articles. This means, either alone or in combination, that :
- a non-wrapped cord which is fixed enough and tight enough to enable easy processing and to prevent sleeving can be obtained by having the outer layer filaments exerting a force which is directed radially inwards towards the centre of the cord.
- the function of holding the cord fixed through the force once exerted by the wrapping filament is now provided by the force exerted by the outer layer filaments.
- Having the outer layer filaments exerting a force which is directed radially inward can be realized in three principal ways or in any combination of the three ways.
- a first way to exert a force which is directed radially inward is to provide the outer layer filaments with residual torsions which tend to close the steel cord.
- the "number of residual torsions" are herein defined as the number of revolutions one end of a specified length of cord or filament is allowed to turn freely.
- the degree of residual torsions of the outer layer filaments in the direction of closing of the cord is made as high as possible, nevertheless the degree of residual torsions of the outer filaments is limited in order to avoid other kinds of processability problems.
- the direction of closing of the cord is obtained by turning the outer layer filaments in the same direction as the direction of the previous twisting of the steel cord. In order to obtain a torsion balance in the steel cord some or all of the filaments other than the outer filaments have residual torsions which tend to open the steel cord.
- a second way to exert a force which is directed radially inward is to preform the outer layer filaments so that they have a preforming ratio, as defined hereinafter, which is smaller than or equal to one hundred per cent.
- the "preforming ratio" of a particular filament is herein defined as follows : In order to avoid the sleeving of the cord, the preforming ratio of the outer layer filaments is kept as low as possible. The preforming ratio of the outer layer filaments, however, must have a lower limit in order to avoid flare, i.e. the spreading of the filament ends after cutting of the cord.
- a third way to exert a force which is directed radially inward is to put the outer layer filaments in the steel cord under a tensile force.
- the outer layer filaments are put under a tensile force in the steel cord, if after careful disentangling of the outer filaments, the twist pitch of the disentangled outer filaments is smaller than the twist pitch of the steel cord. In order to obtain a tension balance in the steel cord, some or all of the filaments other than the outer layer filaments are put under a compressive force in the steel cord.
- At least part of the surface of the filaments is provided with a lubricant in order to obtain a steel cord which slides more easily through narrow openings and which is less prone to sleeving.
- the lubricant must be of a kind that does not harm the adhesion to the elastomer and preferably of a kind that will promote the adhesion of the steel cord to the elastomer.
- the steel cord as a whole is preferably free of residual torsions and has no flare.
- the steel cord has a centre structure of only one (outer) layer.
- the layer structure consists of three centre filaments and the outer layer consists of nine layer filaments.
- the centre structure consists of only one centre filament and the outer layer consists of six layer filaments.
- the diameter of the centre filament may be greater that the diameter of the layer filaments. Diameter differences of 0.02 to 0.10 mm, e.g. of 0.02 to 0.06 mm, are common.
- the steel cord has a centre structure, an intermediate layer and an outer layer.
- the centre structure consists of one centre filament, the intermediate layer of six intermediate layer filaments and the outer layer of twelve outer layer filaments.
- the centre structure consists of three centre filaments, the intermediate layer of nine intermediate layer filaments and the outer layer of fifteen outer layer filaments.
- the diameter of the centre filaments may be larger than the diameter of the intermediate and outer layer filaments. Diameter differences of 0.02 to 0.10 mm are common.
- the part load elongation of any of the centre filaments is preferably smaller that the part load elongation of any of the outer layer filaments.
- the term "part load elongation" is herein defined as the increase in length of a gauge length at a tension of between 0 to 2.5 Newton and of another predetermined tension between 20 and 50 Newton.
- the part load elongation of an individual steel filament is measured on the individual steel filament after twisting of the steel cord and after careful - i.e. without plastically deforming - disentangling of the steel filament from out of the steel cord.
- the part load elongation of any of the intermediate layer filaments is preferably smaller than the part load elongation of any of the outer layer filaments.
- FIGURE 1 schematically illustrates the phenomenon of sleeving.
- the steel cord 10 is drawn through a small opening, and loses its compactness, i.e. the centre filaments no longer contact intermediate layer filaments and/or the intermediate layer filaments no longer contact outer layer filaments. This is to be avoided in the case of compact cords, especially if these compact cords are to lie very close to one another in an elastomeric ply of a radial tyre, particularly in a carcass ply or particularly in the case of the process of embedding the compact cords in an elastomeric ply in an extrusion process.
- a compact steel cord is considered to be a non-sleeving steel cord if it remains a compact cord, i.e. with the outer layer filaments 12 contacting radially the inner filaments, after pulling a length of six metres of a steel cord 10, with both ends burnt (in order to avoid lengthwise shifting of the individual filaments with respect to one another), through a die 14 which has an opening equal to the diameter of the steel cord 10.
- the sleeving phenomenon has a cumulative effect : if sleeving occurs, the diameter of the steel cord 10 before the die 14 gradually increases over the length of the steel cord and forms a so-called "blister".
- FIGURE 2(a) shows the cross-section of a first embodiment of the present invention, i.e. a steel cord 10 with a centre structure of three centre filaments 16 and only one (outer) layer with nine outer layer filaments 12, 13.
- An example of such a cord is : 3 x 0.25 / 9 x 0.23
- Arrow 18 designates the twisting direction of the steel cord 10 (e.g. in Z-direction).
- the non-sleeving has been realized by providing the outer layer filaments 12, 13 with residual torsions in the same direction as the twisting direction of the steel cord 10. The direction of these residual torsions is designated by arrow 20.
- FIGURE 2(b) shows another way of realizing a non-sleeving cord.
- the helicoid of the disentangled outer layer filament 12 has a diameter D which is smaller than the diameter D o of the helicoid of the outer layer filament 12 in the twisted steel cord 10 (22 designates the virtual cylinder around the twisted steel cord).
- the preforming ratio of the outer layer filaments is smaller than 100 %.
- FIGURE 3(a) shows the cross-section of a second embodiment of a steel cord 10 according to the present invention.
- the steel cord 10 has a centre consisting of one single centre filament 16, an intermediate layer of six intermediate layer filaments 24 and an outer layer of twelve outer layer filaments 12, 13 : outer layer filaments 12 which contact only one intermediate layer filament 24 and outer layer filaments 13 which contact two intermediate layer filaments 24.
- An example of such a cord is as follows : 1 x 0.22 / 6 x 0.20 / 12 x 0.20
- the direction of twisting of the steel cord has been designated by arrow 18 (e.g. Z direction).
- the outer layer filaments have residual torsions in the Z-direction (see arrow 20) which tend to close the steel cord.
- the intermediate layer filaments 24 have residual torsions in the S-direction, i.e. residual torsions which tend to open the steel cord.
- Figure 3(b) shows another way of realizing a non-sleeving cord : the preforming ratio (D/D o ) x 100 of the outer layer filaments 12, 13 is smaller than 100 %. As illustrated by FIGURE 3(c), the preforming ratio (D/D o ) x 100 of the intermediate layer filaments 24 can be greater than 100 %.
- FIGURES 4 and 5 illustrate the part load elongation (PLE) of the individual disentangled steel filaments (not of the whole steel cord) of steel cords according to the present invention.
- the abscissa is the increase in length or elongation
- the Y coordinate is the tension (2.5 N - 50 N) exerted on the individual disentangled steel filaments.
- FIGURE 4 corresponds to the embodiment where the non-sleeving has been realized by the residual torsions of the outer layer filaments which close the cord.
- the PLE-values of the intermediate layer filaments 24 are represented by curves 28 which are all within a narrow range.
- the PLE values of outer layer filaments 13 which contact two intermediate layer filaments 24, are represented by curves 30 which are also within a narrow range.
- the PLE-values of outer layer filaments 12 which contact only one intermediate filament 24, are represented by curves 32 which are also within a narrow range.
- FIGURE 5 corresponds to the embodiment where the non-sleeving has been realized by preforming ratios of the outer filaments which are smaller than 100 %.
- the PLE-values of the intermediate layer filaments 24 are again represented by curves 28 which are all within a narrow range.
- the PLE-values of all the outer layer filaments 12 and 13 are now within the same narrow range and are represented by curves 34.
- FIGURE 6 A method of manufacturing steel cords according to the present invention is illustrated in FIGURE 6.
- the individual steel filaments 12, 13, 16 and 24 are drawn from the supply spools 36 and guided via a distributing disc 38 to a twisting die 40.
- a lubricant can be added to the steel filaments as they enter into the twisting die 40.
- the filaments are directed to a guiding pulley 42 where they receive a first twist for each rotation of flyer 44.
- the (partially) twisted cord is guided over flyer 44 to a reversing pulley 46 where the cord receives a second twist for each rotation of flyer 44.
- the twisted cord 10 is subsequently led to a rotating false twister 48 which, as is generally known in the art, can free the whole steel cord of residual torsion.
- a capstan 50 draws the steel cord through all the upstream steps.
- the steel cord is further led to a straightener 52 and wound over a guiding pulley 54 on spool 56.
- the embodiment of the outer layer filaments 12, 13 having residual torsions which tend to close the steel cord 10 can be realized by giving the outer layer filaments 12, 13 torsions which are opposite in direction to and smaller in number than the torsions given to the outer layer filaments and to the steel cord during the twisting process. Tuning of the revolution speed of the false twister 48 can free the whole steel cord 10 of residual torsion, while the outer layer filaments 12, 13 tend to close the steel cord 10 and the intermediate layer filaments 24 tend to open the steel cord 10.
- the embodiment of the outer layer filaments 12, 13 having a preforming ratio smaller than 100 % can be realized by correct location of the guiding holes for the outer layer filaments in the distributing disc 38 and by suitably arranging the distance between the distributing disc 38 and the twisting die 40. The greater the angle formed by the outer layer filaments 12, 13 and the centre filament 16 when approaching the twisting die 40, the greater the preforming degree.
- the embodiment where the outer layer filaments are under a tensile force in the cord can be realized by drawing a length for the outer layer filaments 12, 13 from the supply spools 36 which is slightly insufficient and thus smaller than the length really needed in the final twisted cord. This can be obtained by preventing the twists given to the cord and the filaments from travelling upstream from reversing pulley 46 to guiding pulley 42.
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- Ropes Or Cables (AREA)
Abstract
Description
- The present invention relates to a steel cord adapted for the reinforcement of elastomeric articles such as the carcass plies and breaker plies of pneumatic radial tyres, conveyor belts, hoses and timing belts.
- In the art of using steel cords adapted to reinforce elastomeric articles a general trend towards a simpler steel cord construction which can be manufactured in one single twisting step and consisting of fewer and fewer steel filaments has been recognised. Recently, in the art of reinforcing truck tyres, there has been a trend toward using non-wrapped layered steel cord construction.
- It is known that providing a layered steel cord construction with a wrapping filament influences the properties and behaviour of steel cord construction, especially the stiffness and the elasticity.
Simply omitting the wrapping filament without amending the properties of the other steel filaments, constituting the steel cord, in order to fill in the demand for non-wrapped constructions can lead to a great many problems of processability. In particular, irregular spacing of the non-wrapped layered steel cord construction has been observed in the elastomeric plies. - It is an object of the present invention to reduce the problems of the prior art.
It is another object of the present invention to provide for a non-wrapped steel cord with good processability properties. It is further object of the present invention to provide for a non-wrapped steel cord which does not lead to irregular spacing in elastomeric plies. - According to the present invention, there is provided a steel cord adapted for the reinforcement of elastomeric articles. The steel cord comprises a centre structure of one to five centre filaments and a maximum of two layers of layer filaments surrounding said centre : an outer layer of outer layer filaments and, possibly, one or more intermediate layers of intermediate layer filaments between the centre structure and the outer layer. All the centre filaments and all the layer filaments have the same twist hand and the same twist pitch. The outer layer filaments exert a force which is directed radially inward and which is of such a magnitude that sleeving of the steel cord is prevented.
- A steel cord "adapted for use in the reinforcement of elastomeric articles" means that the steel cord has the necessary features to reinforce elastomeric articles. This means, either alone or in combination, that :
- the steel cord comprises steel filaments with a diameter ranging from 0.05 mm to 0.80 mm, and preferably from 0.05 mm to 0.45 mm ;
- the steel filaments are coated with a layer that promotes adhesion to the elastomer ; in the case of a rubber elastomer, copper alloy coatings such as brass (either low - 63.5 % Cu - or high copper - 67.5 % Cu) or a complex brass coating (Ni + brass, brass + Co...) having a thickness of 0.15 to 0.35 µm are particularly suitable ;
- the steel filaments have a composition which is along the following lines : a carbon content ranging from 0.70 to 0.98 %, a manganese content ranging from .10 to 1.10 %, a silicon content ranging from .10 to 0.90 %, sulphur and phosphorous contents limited to 0.15 %, preferably to 0.010 % ; additional elements such as chromium (up to 0.20-0.40 %), copper (up to 0.20 %) and vanadium (up to 0.30 %) may be added.
- Layered steel cord construction where all the centre filaments and all the layer filaments have the same twist hand and the same twist pitch are called compact cord constructions. The present inventors have discovered that the problem of spacing of the non-wrapped steel cords in the elastomeric plies is due to the outer layer filaments being over length or due to insufficient tension in the outer layer filaments, the filaments in the cord no longer contact one another when drawn through an opening which is equal to the diameter of the steel cord (sleeving will be described in more detail with reference to the drawings). It is a fact that the wrapping filament of wrapped compact cord constructions compensates for a number of imperfections in the remaining cord. The wrapping filament, if put under sufficient tensile tensions, holds the cord tightly together. A non-wrapped cord which is fixed enough and tight enough to enable easy processing and to prevent sleeving can be obtained by having the outer layer filaments exerting a force which is directed radially inwards towards the centre of the cord. In other words, the function of holding the cord fixed through the force once exerted by the wrapping filament, is now provided by the force exerted by the outer layer filaments.
- Having the outer layer filaments exerting a force which is directed radially inward can be realized in three principal ways or in any combination of the three ways.
- A first way to exert a force which is directed radially inward is to provide the outer layer filaments with residual torsions which tend to close the steel cord.
The "number of residual torsions" are herein defined as the number of revolutions one end of a specified length of cord or filament is allowed to turn freely.
In order to avoid sleeving of the cord, the degree of residual torsions of the outer layer filaments in the direction of closing of the cord is made as high as possible, nevertheless the degree of residual torsions of the outer filaments is limited in order to avoid other kinds of processability problems. The direction of closing of the cord is obtained by turning the outer layer filaments in the same direction as the direction of the previous twisting of the steel cord.
In order to obtain a torsion balance in the steel cord some or all of the filaments other than the outer filaments have residual torsions which tend to open the steel cord. - A second way to exert a force which is directed radially inward is to preform the outer layer filaments so that they have a preforming ratio, as defined hereinafter, which is smaller than or equal to one hundred per cent.
The "preforming ratio" of a particular filament is herein defined as follows :
In order to avoid the sleeving of the cord, the preforming ratio of the outer layer filaments is kept as low as possible. The preforming ratio of the outer layer filaments, however, must have a lower limit in order to avoid flare, i.e. the spreading of the filament ends after cutting of the cord. - A third way to exert a force which is directed radially inward is to put the outer layer filaments in the steel cord under a tensile force.
- The outer layer filaments are put under a tensile force in the steel cord, if after careful disentangling of the outer filaments, the twist pitch of the disentangled outer filaments is smaller than the twist pitch of the steel cord.
In order to obtain a tension balance in the steel cord, some or all of the filaments other than the outer layer filaments are put under a compressive force in the steel cord. - Preferably, at least part of the surface of the filaments is provided with a lubricant in order to obtain a steel cord which slides more easily through narrow openings and which is less prone to sleeving. The lubricant must be of a kind that does not harm the adhesion to the elastomer and preferably of a kind that will promote the adhesion of the steel cord to the elastomer.
- In order to facilitate further the processability of the steel cord, the steel cord as a whole is preferably free of residual torsions and has no flare.
- In a first embodiment of the present invention, the steel cord has a centre structure of only one (outer) layer.
In one example of this first embodiment the layer structure consists of three centre filaments and the outer layer consists of nine layer filaments.
In another example the centre structure consists of only one centre filament and the outer layer consists of six layer filaments. - In both of these examples the diameter of the centre filament may be greater that the diameter of the layer filaments. Diameter differences of 0.02 to 0.10 mm, e.g. of 0.02 to 0.06 mm, are common.
- In a second embodiment of the present invention, the steel cord has a centre structure, an intermediate layer and an outer layer. In one example of this second embodiment the centre structure consists of one centre filament, the intermediate layer of six intermediate layer filaments and the outer layer of twelve outer layer filaments.
In another example the centre structure consists of three centre filaments, the intermediate layer of nine intermediate layer filaments and the outer layer of fifteen outer layer filaments. In both examples the diameter of the centre filaments may be larger than the diameter of the intermediate and outer layer filaments. Diameter differences of 0.02 to 0.10 mm are common. - The part load elongation of any of the centre filaments is preferably smaller that the part load elongation of any of the outer layer filaments.
The term "part load elongation" is herein defined as the increase in length of a gauge length at a tension of between 0 to 2.5 Newton and of another predetermined tension between 20 and 50 Newton. The part load elongation of an individual steel filament is measured on the individual steel filament after twisting of the steel cord and after careful - i.e. without plastically deforming - disentangling of the steel filament from out of the steel cord.
In the case of the second embodiment, the part load elongation of any of the intermediate layer filaments is preferably smaller than the part load elongation of any of the outer layer filaments. - With respect to the part load elongation of the outer layer filaments, two subembodiments are possible :
- (1) the part load elongation of any of the outer layer filaments is within a narrow range ;
- (2) the part load elongation of any of those outer layer filaments that contact two intermediate layer filaments is smaller than the part load elongation of any of those outer layer filaments that contact only one intermediate layer filament.
- The invention will now be described in more detail with reference to the accompanying drawings wherein
- FIGURE 1 schematically illustrates the phenomenon of sleeving ;
- FIGURE 2(a) illustrates a cross section of a cord according to a first embodiment of the present invention ;
- FIGURE 2(b) illustrates an outer layer filament taken out of a cord according to a first embodiment of the present invention ;
- FIGURE 3(a) illustrates a cross-section of a cord according to a second embodiment of the present invention ;
- FIGURE 3(b) illustrates an outer layer filament taken out of a cord according to a second embodiment of the present invention ;
- FIGURE 3(c) illustrates an intermediate filament taken out of a cord according to a second embodiment of the present invention ;
- FIGURES 4 and 5 show curves of part load elongation of filaments taken out of a cord according to the second embodiment of the present invention ;
- FIGURE 6 schematically illustrates the way of manufacturing a steel cord according to the present invention.
- FIGURE 1 schematically illustrates the phenomenon of sleeving. The
steel cord 10 is drawn through a small opening, and loses its compactness, i.e. the centre filaments no longer contact intermediate layer filaments and/or the intermediate layer filaments no longer contact outer layer filaments. This is to be avoided in the case of compact cords, especially if these compact cords are to lie very close to one another in an elastomeric ply of a radial tyre, particularly in a carcass ply or particularly in the case of the process of embedding the compact cords in an elastomeric ply in an extrusion process. - In the context of the present invention, a compact steel cord is considered to be a non-sleeving steel cord if it remains a compact cord, i.e. with the
outer layer filaments 12 contacting radially the inner filaments, after pulling a length of six metres of asteel cord 10, with both ends burnt (in order to avoid lengthwise shifting of the individual filaments with respect to one another), through a die 14 which has an opening equal to the diameter of thesteel cord 10. The sleeving phenomenon has a cumulative effect : if sleeving occurs, the diameter of thesteel cord 10 before the die 14 gradually increases over the length of the steel cord and forms a so-called "blister". Should a change in filament position occur within the length of the steel cord, sleeving is stopped temporarily when the change in filament position passes through the die, i.e. the blister disappears. A cord which is prone to sleeving, however, starts again forming a blister after the change in filament position has passed through the die. - FIGURE 2(a) shows the cross-section of a first embodiment of the present invention, i.e. a
steel cord 10 with a centre structure of threecentre filaments 16 and only one (outer) layer with nineouter layer filaments
An example of such a cord is :
3 x 0.25 / 9 x 0.23
Arrow 18 designates the twisting direction of the steel cord 10 (e.g. in Z-direction). The non-sleeving has been realized by providing theouter layer filaments steel cord 10. The direction of these residual torsions is designated byarrow 20. - FIGURE 2(b) shows another way of realizing a non-sleeving cord. The helicoid of the disentangled
outer layer filament 12 has a diameter D which is smaller than the diameter Do of the helicoid of theouter layer filament 12 in the twisted steel cord 10 (22 designates the virtual cylinder around the twisted steel cord). In other words the preforming ratio of the outer layer filaments is smaller than 100 %. - FIGURE 3(a) shows the cross-section of a second embodiment of a
steel cord 10 according to the present invention. Thesteel cord 10 has a centre consisting of onesingle centre filament 16, an intermediate layer of sixintermediate layer filaments 24 and an outer layer of twelveouter layer filaments 12, 13 :outer layer filaments 12 which contact only oneintermediate layer filament 24 andouter layer filaments 13 which contact twointermediate layer filaments 24.
An example of such a cord is as follows :
1 x 0.22 / 6 x 0.20 / 12 x 0.20
The direction of twisting of the steel cord has been designated by arrow 18 (e.g. Z direction). The outer layer filaments have residual torsions in the Z-direction (see arrow 20) which tend to close the steel cord. In order to realize a torsion balance and a steel cord which is as a whole free of residual torsion, theintermediate layer filaments 24 have residual torsions in the S-direction, i.e. residual torsions which tend to open the steel cord. - Figure 3(b) shows another way of realizing a non-sleeving cord : the preforming ratio (D/Do) x 100 of the
outer layer filaments
As illustrated by FIGURE 3(c), the preforming ratio (D/Do) x 100 of theintermediate layer filaments 24 can be greater than 100 %. - FIGURES 4 and 5 illustrate the part load elongation (PLE) of the individual disentangled steel filaments (not of the whole steel cord) of steel cords according to the present invention. The abscissa is the increase in length or elongation, the Y coordinate is the tension (2.5 N - 50 N) exerted on the individual disentangled steel filaments.
- FIGURE 4 corresponds to the embodiment where the non-sleeving has been realized by the residual torsions of the outer layer filaments which close the cord. The PLE-values of the
intermediate layer filaments 24 are represented bycurves 28 which are all within a narrow range. The PLE values ofouter layer filaments 13 which contact twointermediate layer filaments 24, are represented bycurves 30 which are also within a narrow range. Finally, the PLE-values ofouter layer filaments 12 which contact only oneintermediate filament 24, are represented bycurves 32 which are also within a narrow range.
FIGURE 5 corresponds to the embodiment where the non-sleeving has been realized by preforming ratios of the outer filaments which are smaller than 100 %. The PLE-values of theintermediate layer filaments 24 are again represented bycurves 28 which are all within a narrow range. The PLE-values of all theouter layer filaments curves 34. - A method of manufacturing steel cords according to the present invention is illustrated in FIGURE 6. Starting from the left side of FIGURE 6, the
individual steel filaments disc 38 to a twistingdie 40. A lubricant can be added to the steel filaments as they enter into the twisting die 40. The filaments are directed to a guidingpulley 42 where they receive a first twist for each rotation offlyer 44. The (partially) twisted cord is guided overflyer 44 to a reversingpulley 46 where the cord receives a second twist for each rotation offlyer 44. Thetwisted cord 10 is subsequently led to a rotatingfalse twister 48 which, as is generally known in the art, can free the whole steel cord of residual torsion. Acapstan 50 draws the steel cord through all the upstream steps. The steel cord is further led to astraightener 52 and wound over a guidingpulley 54 onspool 56. - The embodiment of the
outer layer filaments steel cord 10 can be realized by giving theouter layer filaments false twister 48 can free thewhole steel cord 10 of residual torsion, while theouter layer filaments steel cord 10 and theintermediate layer filaments 24 tend to open thesteel cord 10.
The embodiment of theouter layer filaments disc 38 and by suitably arranging the distance between the distributingdisc 38 and the twisting die 40. The greater the angle formed by theouter layer filaments centre filament 16 when approaching the twisting die 40, the greater the preforming degree. - The embodiment where the outer layer filaments are under a tensile force in the cord can be realized by drawing a length for the
outer layer filaments pulley 46 to guidingpulley 42.
Claims (24)
- A steel cord adapted for the reinforcement of elastomeric articles, such a steel cord comprising a centre structure of one to five centre filaments and at least one layer of layer filaments surrounding said centre : an outer layer of outer layer filaments and, possibly, one or more intermediate layers of intermediate layer filaments between the centre structure and the outer layer, all the centre filaments and all the layer filaments having the same twist and having the same twist pitch, the outer layer filaments exerting a force which is directed radially inward and which is of such a magnitude that sleeving of the steel cord is prevented.
- A steel cord according to claim 1 wherein the steel cord has no wrapping filament.
- A steel cord according to any of the preceding claims wherein at least part of the surface of the filaments has been provided with a lubricant.
- A steel cord according to any of the preceding claims wherein the steel cord has only one layer of layer filaments.
- A steel cord according to claim 4 wherein the centre structure consists of three centre filaments.
- A steel cord according to any of claims 4 or 5 wherein the layer consists of nine layer filaments.
- A steel cord according to claim 4 wherein the centre structure consists of one centre filament.
- A steel cord according to any of claims 4 or 7 wherein the layer consists of six layer filaments.
- A steel cord according to any of claims 4 to 8 wherein all the centre filaments have the same diameter, all the layer filaments have the same diameter and wherein the diameter of the centre filaments is greater than the diameter of the layer filaments.
- A steel cord according to any of claims 1 to 3 wherein the steel cord has an intermediate layer of intermediate layer filaments.
- A steel cord according to claim wherein all the centre filaments have the same diameter, all the intermediate layer filaments have the same diameter and all the outer layer filaments have same diameter and wherein the diameter of the centre filaments is greater than the diameter of the intermediate layer filaments.
- A steel cord according to any of claims 10 to 11 wherein the number of centre filaments is one, the number of intermediate layer filaments is six and the number of outer layer filaments is twelve.
- A steel cord according to any of claims 10 to 11 wherein the number of centre filaments is three, the number of intermediate layer filaments is nine and the number of outer layer filaments is fifteen.
- A steel cord according to any of the preceding claims wherein the outer layer filaments have residual torsions which tend to close the steel cord.
- A steel cord according to any of claims 10 to 14 wherein the intermediate layer filaments have residual torsions which tend to open the steel cord.
- A steel cord according to any of the preceding claims wherein the centre filaments have residual torsions which tend to open the steel cord.
- A steel cord according to any of the preceding claims wherein the outer layer filaments have a preforming ratio which is smaller than or equal to one hundred per cent.
- A steel cord according to any of the preceding claims wherein the outer layer filaments are under a tensile force in the cord.
- A steel cord according to any of claims 10 to 18 wherein the intermediate layer filaments are under a compressive force in the cord.
- A steel cord according to any of the preceding claims wherein the part load elongation of any of the centre filaments is smaller than the part load elongation of any of the outer layer filaments.
- A steel cord according to any of claims 10 to 20 wherein the part load elongation of any of the intermediate layer filaments is smaller than the part load elongation of any of the outer layer filaments.
- A steel cord according to claims 10 to 21 wherein the part load elongation of any of those outer layer filaments that contact two intermediate layer filaments is smaller than the part load elongation of any of those outer layer filaments that contact only one intermediate layer filament.
- A steel cord according to any of the preceding claims wherein the steel cord as a whole is free of residual torsion.
- A steel cord according to any of the preceding claims wherein the steel cord has no flare.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP19940201134 EP0627520B1 (en) | 1993-06-02 | 1994-04-25 | Compact steel cord with no wrapping filament |
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP93201572 | 1993-06-02 | ||
EP93201572 | 1993-06-02 | ||
EP19940201134 EP0627520B1 (en) | 1993-06-02 | 1994-04-25 | Compact steel cord with no wrapping filament |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0627520A1 true EP0627520A1 (en) | 1994-12-07 |
EP0627520B1 EP0627520B1 (en) | 1998-12-02 |
Family
ID=26133828
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19940201134 Expired - Lifetime EP0627520B1 (en) | 1993-06-02 | 1994-04-25 | Compact steel cord with no wrapping filament |
Country Status (1)
Country | Link |
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EP (1) | EP0627520B1 (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0711868A1 (en) * | 1994-11-14 | 1996-05-15 | Bridgestone Metalpha Corporation | Steel cord for reinforcing a rubber product |
EP1033435A1 (en) * | 1999-03-04 | 2000-09-06 | N.V. Bekaert S.A. | Steel cord with polymer core |
EP1219746A1 (en) * | 2000-12-28 | 2002-07-03 | PIRELLI PNEUMATICI S.p.A. | Metal cord for reinforcing a vehicle tyre |
CN103298996A (en) * | 2011-01-10 | 2013-09-11 | 贝卡尔特公司 | Compact steel cord |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
ATE334251T1 (en) * | 2002-02-14 | 2006-08-15 | Bekaert Sa Nv | COMPACT STEEL CABLE |
EA024603B9 (en) | 2011-01-10 | 2018-04-30 | Нв Бекаэрт Са | Compact steel cord |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0143767A1 (en) * | 1983-09-02 | 1985-06-05 | N.V. Bekaert S.A. | Steel cord for rubber articles |
-
1994
- 1994-04-25 EP EP19940201134 patent/EP0627520B1/en not_active Expired - Lifetime
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0143767A1 (en) * | 1983-09-02 | 1985-06-05 | N.V. Bekaert S.A. | Steel cord for rubber articles |
Non-Patent Citations (1)
Title |
---|
17534: "Process for the manufacture of a strand, as well as a strand made according to this process, and elastomer or synthetic material objects reinforced with such strands", RESEARCH DISCLOSURE, no. 175, November 1978 (1978-11-01), EMSWORTH GB, pages 26 - 28 * |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0711868A1 (en) * | 1994-11-14 | 1996-05-15 | Bridgestone Metalpha Corporation | Steel cord for reinforcing a rubber product |
EP1033435A1 (en) * | 1999-03-04 | 2000-09-06 | N.V. Bekaert S.A. | Steel cord with polymer core |
WO2000052254A1 (en) * | 1999-03-04 | 2000-09-08 | N.V. Bekaert S.A. | Steel cord with polymer core |
EP1219746A1 (en) * | 2000-12-28 | 2002-07-03 | PIRELLI PNEUMATICI S.p.A. | Metal cord for reinforcing a vehicle tyre |
CN103298996A (en) * | 2011-01-10 | 2013-09-11 | 贝卡尔特公司 | Compact steel cord |
CN103298996B (en) * | 2011-01-10 | 2016-01-06 | 贝卡尔特公司 | Compact steel cord |
CN103298996B8 (en) * | 2011-01-10 | 2019-12-03 | 贝卡尔特公司 | Compact steel cord |
Also Published As
Publication number | Publication date |
---|---|
EP0627520B1 (en) | 1998-12-02 |
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