one , Overview
(I) Core stranding
one . Conductor stranding The so-called stranding refers to the stranding of several single wires with the same diameter or different diameters in a certain direction and with certain rules to form a whole stranded wire core. When the stranded conductor is directly used as a wire, it is called bare strand, such as steel cored aluminum strand, aluminum clad steel cored aluminum strand, etc; When twisted wires are used as conductors of insulated wires and cables, they are called stranded wire cores and are the main components of insulated wires and cables.
2 . The cabling of insulated wire cores is the process of twisting several insulated wire cores or unit groups into cable cores according to certain rules. Cabling is also twisting. In addition to twisting, the cabling process also includes cabling filling, tape wrapping and other processes.
3 Characteristics of core stranding
3.1 Good flexibility Due to the use of wires and cables in different occasions, the carrying capacity is different, and the cross-section of the conductor is also large and small. As the cross-section of the conductor increases, the diameter of the conductor also increases, making it difficult to bend the conductor. If multiple single wires with small diameters are twisted together, the bending capacity of the conductor can be improved, which is convenient for the processing, manufacturing, installation and laying of wires and cables.
three point two Stabilizing the stranded wire cores twisted by several single wires in a certain direction and rule. Since the position of each single wire in the stranded wire is in the extension area of the upper part of the stranded wire and the compression area of the lower part of the stranded wire in turn, when the two ends of the stranded wire bend downward, each single wire is subject to the same extension force and compression force, and the single wire will not be extended and compressed, The strand will not deform. If multiple single wires are not twisted but are combined in parallel to form a harness, when the harness is bent, the upper single wire will be embedded in the harness, and the lower single wire will also be compressed toward the center of the harness due to the length change, thus changing the shape of the harness.
3.3 Good reliability Single wire is used as the conductor of wire and cable, which is vulnerable to the non-uniformity of materials or defects produced in manufacturing, affecting the reliability of a single conductor core. With multiple single wire twisted cores, such defects will be dispersed, and will not be concentrated at a certain point of the conductor. The reliability of the conductor is much stronger, especially at the joints of the conductors.
3.4 The strength of a single wire with high strength and the same section size is higher than that of a single wire with the same section size compared with multiple strands.
4 . Core stranding forms The stranding forms are mainly divided into regular stranding and irregular stranding (bunching). Normal stranding can be divided into normal concentric single strand stranding and normal concentric strand stranding (multiple stranding). Normal concentric single wire stranding can also be divided into ordinary stranded wire (copper, aluminum stranded wire) and combined stranded wire (steel cored aluminum stranded wire).
4.1 Normal concentric single strand
4.1.1 Ordinary twisted wires are regularly twisted layer by layer with single wires of the same diameter in concentric circles. The twist direction of each layer is opposite. Their central layer is usually a single wire or two ～ five The cores composed of single wires with the same diameter shall be twisted with one or more layers of single wires.
4.1.2 Composite Strand The representative product of composite strand is aluminum steel cored strand for overhead transmission lines, which is made of single wires with the same diameter, different materials or different diameters and materials.
4.2 Normal concentric stranded wire (multiple stranded wire) Complex stranded wire is a stranded wire that is normally concentric stranded by multiple ordinary strands or bundle wires. The twisting direction of multiple strands is generally opposite to that of strands.
four point three Irregular single stranded (bunched) strands are strands made of multiple single wires twisted together in the same direction and not according to the stranding law. The positions of each single wire are not fixed to each other, and the shape of the bundle is difficult to keep round. Since the strands are all twisted in one direction, which is different from the left and right strands of ordinary strands, the strands are softer than ordinary strands.
4.4 Sectorial compact core and circular compact core
(II) Bundle and Strand
one Characteristics of harness
one point one The bundle is irregularly twisted, which is made of multiple single wires twisted together in the same direction. The position of each single wire in the bundle is not fixed, so seven It is difficult to keep the shape of the bundle composed of more than single wires round; Moreover, since each single wire in the bundle is twisted in one direction, when bending, the sliding allowance between each single wire is large and the bending resistance is small, so the bending performance of the bundle is good. For wire and cable products that need flexibility, most of them use the bundle core.
one point two Calculation of beam line weight The formula for calculating the beam line weight is: W=π/4*d2 *z*k*.ρ kg/km Where: W— Bundle weight; kg/km d— Diameter of single wire in harness; mm Z— Number of single wires in the harness; ρ— Density of conductor (copper conductor is 8.89g/cm k— Twist in coefficient of the bundle.
2 Basic parameters commonly used in strand calculation
two point one Strand pitch h The axial length of a single wire in a twisted wire for one turn around the twisted wire h It is called strand pitch. There is an included angle (acute angle) between the single wire in the stranded wire and the radial direction of the stranded wire α , called the twist angle. Strand pitch h , Strand cross section circumference πD （ D Is the diameter of the stranded wire) and a pitch of the stranded wire L Form a right triangle, as shown in Figure one 。 πD ° h chart 1
two point two Pitch diameter ratio m Pitch diameter ratio m Is the strand pitch length h And strand diameter D Ratio of. m=h/D
two point three Stranding coefficient k From Figure one It can be seen that in one pitch of the twisted wire, the single wire expansion length L To compare a pitch length h To be long, twist factor k That is, in one pitch of the twisted wire, the single wire expansion length L And pitch length h Ratio of. k=L/h=1/ sinθ
two point four Filling factor η In the cross section of the stranded wire, the ratio of the actual area of the conductor to the area calculated according to the overall dimensions of the stranded wire is called the filling factor of the stranded wire η , expressed as a percentage.
three Twisting direction and law of core twisting
three point one Twisting direction The twisting direction is divided into right direction and left direction. The specific judgment method is: spread out the palm (the palm is facing yourself), so that the four fingers are parallel to the axis of the strand. If the direction of the extended right thumb is consistent with the oblique direction of the single line, the twisting direction is right, that is Z To; If the direction of the extended left thumb is the same as the oblique direction of the single line, the twisting direction is left, that is S To.
three point two Twisting rule: In addition to the opposite twisting direction of each layer, the number of single wires in each layer is fixed when the number of single wires in the central layer is fixed. Except the center layer is one Single line is an exception, and the rest of the center layer is two ～ five The number of single wires on the outer layer is more than that on the central layer for concentric normal stranding of single wires six Root. According to the calculation, the number of single wires per layer of concentric stranding is always more than its adjacent inner layer 6.28 Root, take its integer, that is, it is always multiple six Root, regardless of the number of layers and the number of central layers two ～ five Any situation in the root conforms to this stranding rule, and the only exception is when the central layer is one When root, its first one The number of single wires of layer stranded wire is six Root, than central layer one Only more than one single line five Root.
(III) Cabling
one There are two methods for twisting of untwisted and non untwisted strands and cables, one is untwisted and the other is non untwisted. The untwisting twisting is that the wire reel frame equipped with the pay off reel keeps the pay off reel in a horizontal position all the time when the machine rotates with the help of a special device (untwisting device) on it. During the stranding or cabling, the single wire or insulated wire core is only subject to the bending effect, without torsion. Non reversing twisting refers to that the wire reel frame with pay off reel is fixed on the winch cage. When the winch cage rotates once（ three hundred and sixty ）When the pay off reel rotates, the single wire or insulated wire core also twists three hundred and sixty Untwisting is often used for untwisted stranded wire cores. The single wire in the stranded wire has no torsional internal stress (this internal stress can make the stranded wire have the tendency of springback and looseness, especially the overhead wire twisted by hard single wire), and the stranded wire structure is stable. There is also no rebound stress in the round insulated core after it is untwisted and twisted into a cable, which can ensure the accuracy of the roundness and diameter of the cable. Non retwist stranding is mostly used to compress round and sector cores. The stress generated by the torsion of the single wire itself belongs to elastic deformation, which becomes plastic deformation after being compacted by the profiling wheel, thus eliminating the original torsional stress. For the cabling of sector insulated core, it is also necessary to use untwisted stranding to ensure that the cable core is round after cabling.
2 Cabling of circular insulated core
two point one The meaning of cabling is that the cabling process is the process of twisting several insulated wire cores together in a certain direction according to certain rules to form a multi-core cable. In addition to stranding, the cabling process also includes filling the gap between insulated cores and taping the cable cores after cabling. During cabling, the stranded form of insulated wire core adopts concentric normal stranding. If the insulated wire core has the same diameter, it is called symmetrical cabling. If the diameter of insulated wire core is different, it is called asymmetric cabling. In order to avoid the influence of torsional stress on the insulated core during cabling, the round insulated core shall be untwisted and twisted by the cable forming machine with untwisting device or bow cable forming machine. two point two The cabling direction and pitch diameter ratio cabling direction are generally right (for multi-layer twisted control cables, the outermost layer is right, and the adjacent layers are twisted in opposite directions). The section diameter ratio of cabling varies according to different types of cables. The circular core of cross-linked polyethylene insulated cable has a large section diameter ratio due to its hard insulation, which is generally thirty ～ forty ； The pitch diameter ratio of circular core of PVC insulated cable is twenty ～ forty ； Plastic insulated control cable The pitch diameter ratio of wire core shall not be greater than that specified in national standards sixteen ～ twenty 。
two point three Cable wrapping In order to make the cable core no longer deformed after cabling, the insulated core needs to be wrapped on the cabling machine while cabling and filling. For plastic insulated cables, the tape layer only plays a role of tightening, and is often used one ～ two The layer of non-woven fabric (other materials can also be used) tape is wrapped by lapping (one layer or two layers, based on the principle of cable wrapping), and the lapping size is the bandwidth 10% ～ 15% , wrap angle at twenty-five ～ forty Within the range.
three Cabling of sector insulated core
3.1 The fan-shaped core shall be laid in a non rewinding manner. In the process of cabling, the sector insulated core is twisted and rotates around the core itself, which must be synchronized with the cabling to ensure that the apex of the sharp corner of the sector core is always aligned with the center of the cabling circle and ensure the integrity of the cabling core . The sector insulated wire core that is used to form the cable without untwisting must be pre twisted. Pre twisting on the cable forming machine is to twist the sector insulated wire core in the opposite direction of the cable forming, so that the sector insulated wire core first has an elastic deformation in the opposite direction. The twisting angle depends on the size of the cable forming pitch, and also depends on the distance between the paying off reel on the cable forming machine's winch and the cable forming mold. The pitch is small, The longer the distance is, the more pre twist is needed. The smaller section core is more pre twist than the larger section core. Generally, for the sector insulated core on the stranding cage, the pre twist is within the range of half to three turns. For the insulated core with insufficient or excessive pre twist, a small amount of adjustment can be made by adjusting the distance between the cable forming die holder and the junction board, If the pre torque is insufficient, the distance between the mold base and the distribution board shall be reduced, and if the pre torque is excessive, the distance shall be increased.
three point two Mould and pitch of sector core cabling
3.2.1 Cable forming mold: Bakelite or polytetrafluoroethylene materials are generally used. In order not to damage the insulation, steel mold is generally not suitable two ～ three Die, No one The channel mold core plays the role of twisting the cable core, and its aperture is larger than the outer diameter of the cable one ～ 3mm , ensure that the sector cannot roll over; Section two Dao He Di three The channel mold plays the role of compaction and shaping, and its aperture is smaller than the outer diameter of the cable zero ～ 0.5mm about.
3.2.2 The cabling pitch of sector insulated core is larger than that of circular insulated core, which is generally thirty ～ eighty Times.
two Materials and semi-finished products
（1） Materials and properties for stranded wire The materials used for stranded wire mainly include copper single wire, aluminum single wire and galvanized steel wire.
one , Copper Copper (Copper + Silver) content not less than ninety-nine point nine zero ％； Melting point is one thousand and eighty-three ℃ ； twenty ℃ When the density of copper is equal to 8.89×10kg/m Copper has good conductivity, ranking second only to silver two Bit. twenty ℃ Volume resistivity of copper at（ ρ ）Not greater than: zero point zero one seven two four one ， 0.01777 2/m (hard). Our company stipulates that after annealing twenty ℃ Volume resistivity of copper at（ ρ20 ）No Ω.mm2/m (Soft) two greater than 0.01700Ω.mm /m 。 two Aluminum content is not less than ninety-nine point five ％； Melting point is six hundred and fifty-eight point seven ℃ ； twenty ℃ When the density of aluminum is equal to 2.703×103kg/m3 ， twenty ℃ 2 2 Volume resistivity of aluminum at（ ρ20 ）Not greater than: 0.028020Ω.mm /m (Soft), 0.028264Ω.mm /m (hard).
two Some companies stipulate that after annealing twenty ℃ Volume resistivity of copper at（ ρ20 ）Not greater than 0.02760Ω.mm /m 。
3 Zinc content of zinc ingot of galvanized steel wire is not less than 99.85% ； twenty ℃ The density of galvanized steel wire is equal to 7.78×103kg/m3 ； Plating process: hot dip coating or electroplating process coating. The galvanized layer shall be firmly attached to the steel wire, and shall not crack or peel to the extent that it can be wiped off with bare fingers. There should be no gap on the galvanized layer by visual inspection. The galvanized layer should be quite smooth, uniform in thickness, and consistent with good industrial products.
（2） Semi finished products and materials for cabling Semi finished products for cabling are plastic insulated single wires; The materials used for cabling mainly include filling materials and wrapping materials.
one Plastic insulated single wires for cabling of plastic insulated single wires mainly include copper (aluminum) core round (sector) PVC (polyethylene, cross-linked polyethylene) insulated single wires. Insulated cores shall be identified by color, number or other marking methods according to regulations. The insulation layer shall be tightly extruded on the conductor (or refractory layer), and shall be easy to peel without damaging the conductor (or refractory layer). The insulation surface shall be smooth and flat.
two The requirements of filling materials for filling materials are: there is no harmful interaction between the components of the filler and the insulation and sheath, and the heat resistance of the filler should be consistent with the working temperature of the cable; The filler shall be able to peel off without damaging the insulation core. Different types of cables are filled with different filling materials, and plastic cables are filled with molded plastic or polypropylene tear ropes.
3 Wrapping material The function of wrapping tape is to wrap the insulated core after cabling to prevent the insulation core and filler from loosening one ～ two Layer film or tape; The cable core after the cable is fastened also ensures the roundness of the cable core. Plastic insulated cables are generally wrapped with 1~2 Layer non-woven fabric (or other materials) is used to tie the cable core tightly by lapping and wrapping, and the wrapping is round, and the lapping coefficient is 10% ～ 15% , wrap angle at two hundred and fifty ～ four hundred between.
three , stranding equipment and its auxiliary equipment
（1） Wire buncher and strander Wire buncher and strander are two main equipment for producing stranded wire core and bare stranded wire, Whether it is a buncher or a strander, Both include two kinds of movements, One is to rotate all single wires around the central axis of the equipment, The other is to make the stranded conductor straight Linear motion. The combination of these two movements makes a group of single wires become bundle wires or twisted wires with a certain pitch and twist direction. The difference between the buncher and the strander is that the rotation movement of the single wire on the strander around the central axis of the equipment is to enter Completed before the wire drawing die (i.e. the section from paying off to the wire drawing die). The stranded wire only moves in a straight line after passing through the parallel die, and the take-up reel only It plays the role of winding the twisted wire on the plate. The rotation movement of the single wire around the central axis of the equipment and the linear movement of the wire harness on the wire harness machine Dynamic, They are carried out at the same time after the single line enters the parallel die, That is, the take-up reel makes the harness rotate and move forward at the same time, Therefore, the pay off reel of single line can be placed at a fixed position. Since the single wire rotates around the central axis on the strander and buncher The parts are different, so the paying off part often plays a major role in the strander, and the type of strander is usually based on the size of the paying off part The wire buncher is named according to the size of its take-up part. one Since the operation of the wire tying machine is all in the take-up part, and the speed change machine is installed in the rotating rack, the location is limited, which determines that the wire tying machine can only be made into a product with small size and twisting direction. The main types are single pitch wire bonder and double pitch wire bonder. According to the outer diameter of take-up reel, it can be divided into two hundred Type four hundred Type five hundred Type six hundred and thirty Type and one thousand Type, etc. After each single wire in the single pitch wire bonder enters the distribution board, it is wound onto the take-up reel, and the cradle rotates once to generate a pitch; However, in the double pitch wire buncher, each single wire will enter the take-up bar after winding a full circle along the swivel and equipment center, and the wire buncher will generate two pitches every rotation of the swivel. At present, the most commonly used double pitch wire tying machine is characterized by fast speed and high productivity. Transmission calculation of double pitch wire tying machine H=v/2n*1000 Where: h— Harness machine pitch（ mm ） v— Outgoing speed（ m/min ） h— Rotation speed of winch cage（ r/min ） two Tubular stranding machine Tubular stranding machine (pipe stranding machine) is a high-speed stranding machine with untwisting. Its stranding quality is the same as that of cage pipe machine with untwisting, but its productivity is many times higher. It is widely used in the stranding production of copper, aluminum, steel wire and aluminum steel cored strand. The specifications and models of pipe winches are distinguished by the number of pay off reels and the diameter of pay off reels. Common pipe winches include six Disk twelve Disk eighteen There are several kinds of reels, and the diameter of pay off reel is 200mm 、 400mm 、 500mm 、 630mm Etc. During the stranding process of the pipe winch, since the pay off reel does not rotate, the single line is released from the pay off reel, and then goes through the guide wheel and pipe wall to the parallel die. With the rotation of the pipe body, the single line does not rotate around its own axis, and there is no single line torsion, so the stranding process of the pipe winch belongs to reverse twisting stranding. Calculation formula of pipe strander pitch: h=v/n*1000 Where: h— Harness machine pitch（ mm ） v— Outgoing speed（ m/min ） h— Rotation speed of winch cage（ r/min ） three Cage strander The pay off reel of the cage strander (cage strander) is installed in the rotating cage, whose shape is like an iron cage, so it is called cage strander. It is the earliest stranding machine. It can strangle two or three layers of single wires at the same time. The number of single wires twisted at one time is large, the diameter of stranding is large, and the stranding mode can be reversed or not. It is widely used. The disadvantage is that the pay off reel is distributed on the circumference of the winch cage. The winch cage has large volume, large rotary inertia, unable to improve the speed, and low productivity. The calculation formula of strand pitch of cage strander: h=v/n*1000 Where: h— Harness machine pitch（ mm ） v— Outgoing speed（ m/min ） h— Rotation speed of winch cage（ r/min ） four Fork type stranding machine The stranding cage of fork type stranding machine (fork type stranding machine) is composed of a fork shaped frame and a hollow shaft. Each fork shaped frame is equipped with three pay off reels. The number of pay off reels on each section of the stranding cage is designed as required. Generally three Multiple of. Due to the compact structure of the cage of the fork winch, the pay off reel is placed close to the rotating hollow shaft, and there is no floating basket part of the cage winch, so the speed of the fork winch can be increased, the productivity is also high, the equipment price is lower than that of the same type of cage winch, but there is no torsion back device. Calculation formula of strand pitch of fork strander: h=v/n*1000 Where: h— Harness machine pitch（ mm ） v— Outgoing speed（ m/min ） h— Rotation speed of winch cage（ r/min ） five Frame type strander The frame type strander (frame type strander) is compared with the fork type strander. Its wire reels are separately installed on four frames in a vertical layout. The central axis is not subject to the weight load of the wire reel. The wire reel is nine hundred Angular distribution, small turning radius of the winch, double the speed of the cage winch of the same specification, and the winch does not need a supporting wheel, but is supported at both ends by large bearing blocks. The equipment has low noise, and the wire reel can be up and down individually or as a whole. Pneumatic or electric clamping is convenient for operation and shortens the auxiliary time. Single line paying off tension is controlled by pneumatic tension, which can be automatically adjusted. The disadvantage is that it cannot be reversed. Calculation formula of strand pitch of frame strander: h=v/n*1000 Where: h— Harness machine pitch（ mm ） v— Outgoing speed（ m/min ） h— Rotation speed of winch cage（ r/min ）
（2） Cabling machine The equipment used for cabling, that is, the equipment for twisting insulated wire cores together, filling and wrapping them, is called cabling There are two types of cable formers: ordinary type and reel type. Ordinary type cable formers include cage type and reel type.
1 . The medium and small cable forming mechanisms of the cage type cable forming machine cause the cage type, and the twisted part is like the cage of the cage type cable forming machine, 1+6/400 Type and 1+6/1000 Type and other types.
two . Disk type cabling machine Large cabling mechanism is disk type, and the cabling speed is generally 10m/min The following, such as 1+3/1600 、 2+3/1600 and 1+3/2400 And other large cable formers, the largest pay off reels are 1600mm and 2400mm 。 The big winch of the disc type cable former is fastened to a hollow shaft by discs of different sizes. There are three pay off reel racks between the two discs. The pay off reel rack shaft is equipped with a gear mechanism for untwisting. The stranding part of the disc type cabling machine has a main bearing, in which the rear end of the hollow shaft rotates, the front and rear discs are supported by supporting rollers, and the front end of the hollow shaft is a junction board, so that the insulated wire core before stranding can enter the parallel die in a correct way and prevent the insulated wire core from twisting back. No matter disc or cage type cabling machine, there is a star frame to place fillers for cabling. Behind the stranding frame are the support of wire drawing die seat, wrapping head, traction device, take-up device, etc.
three The coiling cable former is a relatively new cable former with high production efficiency and speed 30m/min Above, it has a wide range of applications and can be used for various power cable It can also be used for stranding split conductors of communication cables, control cables and large section ultra-high voltage cables, such as 1+3/300 Model 3 m cabling machine.
（3） Auxiliary equipment In addition to the corresponding main equipment such as strander and buncher, the manufacturing of stranded wire and buncher must also be equipped with rewinder and welding machine Relevant auxiliary equipment such as airport pickup.
one Rewinding machine The so-called rewinding machine is to coil single wire (such as steel wire) into a coiling reel suitable for the equipment, or because the reel does not meet the stranding equipment, or the length of single wire does not meet the production requirements, it is also necessary to coil the single wire from this wire to another suitable reel. When the single wire is rewound, it is subject to repeated bending again, and its surface may be damaged, which also increases the process. Therefore, rewinding should be minimized in production. Rewinding machine is used for rewinding. The rewinding machine is composed of paying off device, take-up device, cable arrangement mechanism, etc., and has drag and drive parts.
two Common welding machines include resistance butt welding machine, silver welding machine, cold press welding machine and cold press clamp. The welding machine currently used by our company is a resistance butt welding machine, which is a method of heating two ends with a large current and applying relative pressure to weld the wires to be welded together: two single wires are clamped into the left and right clamps respectively (note: the ends need to be flat and aligned), and voltage is applied to both ends of the primary coil of the transformer according to the power supply, The secondary coil generates large current through two single wires; Because the contact resistance of the two single wire ends is large, after the large current passes through, a large amount of heat will be generated at the ends, and the two ends will be melted. The two chucks will be pressed horizontally, and the two single wires will be welded together; After proper cooling, take out the thread head and smooth the welding bulge with a file.
IV Maintenance of stranding equipment
Correct and good maintenance of equipment not only makes the equipment durable, but also reduces accidents in operation To improve the product quality and meet the requirements of the process on the equipment, regular maintenance and repair must be carried out.
one All components and parts of the equipment must be complete and easy to use. If there are defects in the parts, they must be repaired or replaced immediately, and they cannot operate with defects.
two Tooling mould and gear replacement must be kept orderly and intact to prevent corrosion damage.
three All assembly parts of the equipment shall be fastened without looseness, and the control and transmission systems shall be kept in good condition.
four . The contact part of the support ring of the equipment hinge cage and the support roller shall be fully contacted, and the center line shall be aligned.
five The equipment wire frame (wire basket) must be stable and not shake, and the wire frame pretorque device shall be well positioned and fixed.
six The brake system of the equipment is intact and flexible, the wrapping head holding brake is flexible and easy to use, and the wrapping belt does not automatically loosen when tightened.
seven The thread take-up ring and traction wheel are well matched, and the thread take-up ring guide wheel can rotate flexibly during operation without deflection (referring to single traction stranding equipment).
eight The take-up device operates normally, and the current indication does not exceed the load requirements; The cable arrangement system is intact and adjusted reliably.
nine The pressing device system is intact, the pressing wheel is not loose, does not bounce, and is firmly fixed.
ten . Due to the large moment of inertia when starting, it is not allowed to start the reverse car without stopping. It must be accelerated gradually after startup, but it cannot run at low speed for a long time. The equipment tension system is intact and needs to be adjusted flexibly. The equipment shall be lubricated with lubricant according to the specified time and method. The details shall be carried out according to different equipment and maintenance procedures.
five , stranding die
（1） Strand mode The moulds commonly used in stranding are wood mould, bakelite mould, steel pressing mould, combined mould PVC Plastic die, polytetrafluoroethylene die, hard alloy die and pressure wheel, etc.
one . The wood mold and bakelite mold are made of hard pear wood, which is very convenient to use in production, but has a short life. They are generally used one ～ 2km The mold hole is large and needs to be replaced. In order to improve the service life, the wooden mold is changed into bakelite mold, which is also made into a huff shape. The service life three ～ 10km 。 It can also be used PVC Plastic mold (or polytetrafluoroethylene plastic mold) can be used to replace bakelite mold, and its service life can be improved PVC For the plastic mold, the requirements for the smoothness of the hole type are high, and the intersection of the hole type must be trimmed into an arc to avoid scratching the wire core.
two Steel die steel die materials are generally selected Y 7 or Y 8 , in a huff shape. Since the outer diameter of the stranded wire is large, and some specifications even exceed the maximum outer diameter specified in the standard, the steel pressing die is used for proper compression to significantly reduce the outer diameter of the stranded wire and ensure the roundness of the core. This kind of die has a long service life, which can generally reach fifty ～ 80km , but the compression diameter should be kept at reduced 5% Otherwise, it is easy to break.
three Profiling wheel Profiling wheel compacts strands of various specifications and shapes. Adjust the size of the roller according to the ratio of the nominal section to the actual section, that is, the filling coefficient. After the pressing wheel is installed according to the process requirements, adjust the compression amount to meet the size requirements. When adjusting, first rough adjustment, then fine adjustment, adjust while driving, and then stop to measure the size until the size meets the specified requirements.
（2） Cable forming mode and tape wrapping mode The molds used for cable forming include pressing mold and tape wrapping mold. These molds are composed of two semicircular molds, and the hole type of the mold is roughly one Sample: The incoming section is a smooth bell mouth to adapt to the transition state of the insulated core when entering the die. The cabling mould shall not be insulated When the core is bent, the line bearing area is a straight line, so that the core will be basically shaped after passing through this area. Wrapping mode and cabling mode basic Almost.
six Analysis and handling of defective products
In the production process, some defective products may be produced due to various reasons, but if prevention is taken in advance, strict measures shall be taken The establishment of a sound quality assurance system can reduce and eliminate the occurrence of defective products. Based on past experience The types, causes and solutions of common defective products are listed.
（1） Judgment and elimination method of defective bundle and stranded wire
one . Over twisting refers to the phenomenon of excessive twisting in the process of twisting, which is in the shape of twist. Causes: First, the number of turns of the stranded wire on the traction wheel is not enough, generally less than four, and the friction force is too small to slip, resulting in excessive twisting. Second, the take-up tension is loose or the take-up reel does not rotate, while the swivel is still rotating, resulting in excessive twisting. Troubleshooting: If the outer layer of the single wire has been severely deformed and damaged, there is no possibility of repair, only cutting. If the single wire is not seriously damaged, separate the rotating part of the equipment from the traction part, rotate it in the opposite direction of the twisting, make the local twisting part return, repair the wire core by hand, wind the redundant single wire onto the take-up reel, pull the equipment and the rotating part together, press the wire with force after the loose over-voltage die, and repair manually with the die, In this way, the production can be restarted.
2 . The single wire breaks during stranding, and the causes of single wire breaking due to lack of strands are as follows:
（ one ）The wire core is broken due to excessive paying off tension.
（ two ）The single wire is loose and disorderly during drawing, the arrangement of wires is not good, and the pressed wires cross the wires, causing the core to break.
（ three ）The material of the single wire itself has cracks, and the mechanical property is poor and brittle.
（ four ）The pay off reel is installed in an improper position and shakes axially, resulting in wire breakage.
（ five ）The single line jumps out of the pulley groove, and the machine is broken. Troubleshooting: adjust the paying off tension,
① Make it appropriate. Pay attention to the selection of incoming line,
② It is found that the stay wire is loose, The machine can only be started after rewinding.
③ Pay attention to the operation method and carefully check the position of the paying off reel to make sure that the laid out wire is not If it does not swing, check whether it jumps out of the guide pulley groove where the single line passes.
④ To check the surface quality of the core Whether there are cracks, slag inclusions, scabs and other defects. If the broken wire occurs in the inner layer and the broken head has gone too long, it cannot be repaired, It is only necessary to cut off the missing strand core. If the broken wire occurs in the outer layer, it should be repaired before starting the machine.
three . The surface of the stranded wire is scratched and the wire core is scratched. The causes are usually as follows: first, the nozzle on the distributor is worn; Second, the single line jumps out of the pulley; The third is to use wood pipe or plastic pipe for threading; Fourth, the positioning pin on the wire pushing plate of the traction equipment is damaged; Fifth, there are foreign matters in the die. Elimination method: replace the threading nozzle on the distribution panel and the wood pipe and plastic pipe for threading, check whether the core direction is normal, protect the core from direct wear with the equipment, check whether the die is intact at any time, and pay attention to the operation method.
four . The causes of back strand and loose strand of single wire in the bundle and stranded wire: First, the tension of paying off is uneven, loose and tight, and the loose core runs too much, causing back strand; Second, the die pass is too large to adjust the tension properly; Third, the die position is improper and the stranding angle is unreasonable; Fourth, the pitch is relatively large. Wire tying machine nineteen Single core of strand and above can only be bundled in the same direction because there is no difference in the direction of the bundle, so the core is twisted irregularly. At present, most manufacturers use the double pitch bundle system, so the bundle bundle system nineteen The core, back strand and loose strand above strand are more serious than that of stranded wire.
Troubleshooting: alignment（ nineteen The first is to improve the paying off device of the bunching line, and adopt more advanced single line paying off tension pay off device, so that the tension of each single line can be adjusted and controlled; The other is to use the guide die, and the diameter of the guide die is the beam line to calculate the outer diameter 97% , so that the tension of the guide die can be properly adjusted; The third is to use a single pitch wire bonder. The products of this wire bonder can reach the level of stranded wire; Fourthly, the harness core with serious back strand and loose strand can also meet the requirements of use by means of over mold rewinding repair; Fifth, adjust the pitch ratio properly. For the back strand and loose strand of stranded wire products, the elimination methods are as follows: first, adjust the paying off tension to make it even; Second, change the die to make the wire core not loose in the die hole. Pay attention to the bell mouth of the die. If the bell mouth has been damaged, it cannot be used; The third is to adjust the position of the die holder to make the stranding angle of the stranded wire reasonable; Fourth, if the stranding pitch is large, it should be reduced appropriately.
five The cause of single line slotting or surface defects in the stranded wire: the defects such as pockmarks, scabs, triangular cracks, and slag inclusions on the surface of the single line are mainly caused by materials. Of course, the surface of the wire core is cracked, which does not rule out that the hole type of the pulling die is unreasonable. At this time, the specific situation needs to be analyzed. The grooving on the surface of the wire core is continuous, which is generally caused by the pulling wire. The lubrication condition of the pulling wire is deteriorated, and the surface is stuck with aluminum. The grooving that is not continuous may be caused by the sticking of foreign matters on the pressing die of the stranded wire. Elimination method: For the aluminum wire slotting when pulling the wire, first check whether the lubrication effect of the wire can meet the requirements of the wire. Timely replace the lubricating oil, replace the wire drawing die, or remove the sundries stuck on the wire drawing die. Carefully check the incoming wire. Timely remove the unqualified incoming wire. At the same time, check whether the wire pressing die is damaged and whether there are sundries. Timely repair and replace it.
6 Causes of single wire diameter being suddenly large, suddenly small or mixed with wrong wire core: single wire diameter being found out to be out of tolerance or mixed with wrong wire core during stranding, the main reason is that the process regulations are not carefully implemented, and the other reason is that there are certain problems in management. Elimination method: If the length of the mixed wire core is not long, it can be removed, replaced, and repaired according to the knitting repair method. If the length is too long, it can't be repaired, so we have to get off the machine and handle it separately. Therefore, the operator shall carefully check and measure before operation. Of course, the manager should also provide a guarantee method, such as whether the wire gauge is too much, whether the tolerance is reasonable, and whether the production scheduling is properly arranged 20/80 In principle, we should seriously consider the problems existing in management to avoid man-made defective products and waste products. Causes of strand looseness of stranded wire core:
（ one ）The pitch is too large, which causes the stranded wire core is not solid, and the die hole is too large, which makes it impossible to press
（ two Regulating effect of consolidation. The bell mouth of the line mold is too large or worn and damaged.
（ three ）The paying off tension is uneven, loose and tight.
（ four ）The pitch ratio of each layer is not well matched.
（ five ）The state of the wire core does not conform to the process regulations, especially the aluminum wire core.
（ six ）The position of the splitter and the die holder is improper. Troubleshooting: first, strictly enforce the process discipline, implement the process operation procedures, properly reduce the excessive pitch, and adjust the paying off tension and the pressing die. The position from the splitter to the die holder is generally adjusted to 200~250mm Is appropriate. For the stranding of some strands with extremely high tensile strength, the method of combined mold can be used, which also has good effect. Of course, it is very important for the operator to operate according to the method specified in the process operation specification.
seven The reason why the stranded wire core is serpentine: the stranded wire core with large cross section and the steel cored aluminum strand core are prone to serpentine bending, which is mainly due to the problems in the stranded wire core, especially when the steel wire is too hard, the tension is not adjusted well, the splitting is not good, and the pressing die does not play a compaction role.
eight Causes of wrong twisting direction and unqualified twisting pitch (mainly due to excessive): wrong twisting direction is mainly due to wrong judgment. When operating, the operator should strengthen the sense of responsibility, strictly follow the process card, and strengthen the flow inspection to prevent man-made defective products and waste products.
nine Causes of disordered wire arrangement and crimping: twisted products are generally supplied in coils. Large section shall be arranged one by one, especially the bottom line shall be arranged neatly. In case of a stay when the cable is reversed, special attention shall be paid to that there shall be no too large gap between the upper and lower layers, and the distance between the rows shall be appropriate, which may lead to crimping. Troubleshooting: First, adjust the take-up tension. When manually arranging the wires, it is better to be able to do so. The second is to change the cable pitch according to the diameter of the wire core. It is the key to arrange the first layer, and it must be arranged neatly; The second floor shall be arranged. During floor adjustment, manual wiring shall be conducted to ensure the wiring quality. The third is to strengthen the sense of responsibility for operation and observe the quality of cabling at any time. If any problem is found, it should be adjusted in time. Pay attention to fixing the two thread ends and the distance between the edges.
（2） Identification and elimination of defective and waste products in cabling In the cabling process, the types and causes of defective products are as follows: Different, but mainly There are similarities in the contents, so the cabling mode will not be discussed. seven S/N one Types of rejected products Causes of core insulation damage one Collision of insulated wire core during transportation and storage after winding down. two The coil of insulated core will damage the core during cabling. three Wrinkle due to improper operation during cabling. 1 2 3 4 5 The paying off tension is too large. Wire nipples clamp wires. The core insulation is wrapped. The wires are not firmly welded. Prevention method for excessive take-up tension one Repair or replace the nozzle, guide wheel, junction plate and die. two Adjust the tension. Pay attention to the quality of insulated core. four Select the appropriate die to correct the die. five Correct the pressing die, pay attention to inspection, and operate correctly two The wire is thinned and broken three The insulation of insulated wire core is scratched and crushed one There are burrs or defects on the inner surface of the pay off reel, guide wheel and pressing die. one Adjust the pretorque angle or the distance between the pressing die and the core guide wheel. two The tension of pay off reel is too large, and the nozzle and conduit are damaged. three The wire core insulation is locally thick, resulting in over mold clamping damage. four Small mold matching. five The center of the die is not corrected. 4 5 Wrong insulation core and wrong serial number caused by careless turning operation of sector shaped insulation core. one Improper pretorque angle. two The wire core on the pay off reel turns over due to the large wire core, and the wire core turns over due to the untwisting of the wire core when the head is separated from the reel. two When the wire core is placed on the two side plates of the wire reel, pay special attention to the angle of the wire core entering the die. Adjust the gear correctly according to the process. one Select the appropriate die. two Adjust the distance between the pressing die and the core guide wheel or the setting out pretorque angle. three Reasonable filling. four Adjust the pressure of the roller. six The cabling pitch does not meet the requirements. The cabling ovality exceeds the allowable range. The number of gear teeth for process replacement is incorrect. one Produce according to the specified pitch. two Repair the tape. three Control the quantity of filling. 1 2 3 4 The hole diameter of the die is large. The wire core enters the mold at an inappropriate angle and is not fully filled. The traction wheel is pressed too tightly. one Adjust the paying off tension. two Repair the tape. three Control the quantity of filling. one Adjust the paying off tension. two Adjusting pitch three Pay attention to the tightness and tidiness of cables one Replace the strip. two If the equipment is abnormal, repair the equipment. three Adjust the gear. Replace the strip or supplement it 7 8 The evenness of the outer diameter of the cable exceeds the allowable range. After the cable is laid, the gap or overlap of the serpentine winding tape (including tape insulation) exceeds the allowable range. The tape (or tape insulation) is scratched or damaged one The cabling pitch is large. two Inclusions in wrapping tape. three Filling too full or too much. one Uneven cabling tension. two Improper cabling pitch three The take-up cable is pressed into a snake shape. one The strip width is incorrect. two Change of starting and stopping time gap or capping. three The gears are replaced incorrectly. The strip thickness is wrong or missing. one The mold aperture is not smooth, and the taper arc is small. two The take-up ring and the junction board have damaged surfaces and scratch the tape. surface 1 9 10 11 12 1 Choose a smooth and well started mold. two Repair the pull ring and junction board to prevent damage. one Adjust the tension. two Adjust the pitch. three Check the materials and replace the unqualified ones.
VII Basic calculation
one . The diameter of single wire is known in production d=0.25mm , number of single wires in harness Z by thirty Stranding coefficient of bundle k by one point zero zero eight , density of conductor ρ by 8.89g/cm3 , find the length L by ten The weight of this kind of harness in kilometers W 。 Solution: ∵ d=0.25mm=0.025cm ， Z=30 ， k=1.008 ρ=8.89g/cm3 ， L=10km=10 6cm ∴ W=π /4 *d 2*Z*k*ρ*L =π /4*(0.025)2*30*1.008*8089*106 ≈131964(G) ≈132(KG) Answer: Length L by ten The weight of this kind of harness in kilometers W About 132kg 。
two . The rotational speed of the winch is known during stranding production r by 100r/min , traction speed v by 28m/min , calculate stranding pitch h 。 Solution: ∵ r=100r/min ， v=28m/min=28000mm/min ∴ h=V/ r =2800/100 =280(mm) Answer: Twisting pitch h by 280mm 。
3 In stranding production, known stranding pitch length h by 580mm , diameter of twisted product D by 29mm , calculate the pitch diameter ratio m 。 Solution: ∵ h=580mm ， D=29mm ∴ m= h /D =580/29 =20( times ) Answer: pitch diameter ratio m by twenty Times.
4 During stranding production, the known outer diameter of stranding products is 20mm , winch speed r by 100r/min , the pitch diameter ratio of the product to be twisted m be equal to eighteen Times, calculate the traction speed v 。 Solution: ∵ D=20mm ， m=18 ， m= h /D ∴ Pitch of twisted products h=m.D=18×20=360 （ mm ）And ∵ r=100r/min ， h=v/h ∴ Traction speed v=h.r =360×100 =36000 （ mm/min ） =36 （ m/min ）Answer: Traction speed v by 36m/min 。
