JPS6346197B2 - - Google Patents

Description

[Detailed Description of the Invention] This invention provides a method for stranding high-strength steel wires such as high-carbon steel wires, especially steel wires for PC, and a stranding machine for the same, in particular, a stranded wire with good straightness without bending tendency. The present invention relates to a manufacturing method and apparatus.

Stranded steel wire, especially stranded steel wire for prestressed concrete (PC), requires linearity for workability during reinforcing, reduction of frictional force during stress introduction, and equalization of stress. Recent PCCV, large tank,
Also, the size of PC steel materials used in large bridges has become significantly larger, and tendons made by bundling a large number of stranded PC steel wires,
For example, a 1000 ton tendon made of 54 7-strand steel wires with an outer diameter of 1/2 inch is used. In that case, the tendons are loaded into the sheath using a pushing machine, but if the tendons, that is, the straightness of each stranded wire is poor, the loading operation becomes difficult. In addition, when stress is introduced into the tendon, if the straightness of the stranded wire is poor, the stress will be non-uniform, and the coefficient of friction between the sheath and the tendon in straight and curved parts is greatly influenced by the straightness. . Twisted wire generally has a structure in which many other strands are twisted around a central strand, and the linearity of each strand and the uniformity of the preform given to the outer strands affect the linearity of the stranded wire. However, the linearity of the central wire has the greatest contribution.

Traditionally, a tubular type wire stranding machine has been used to manufacture PC steel stranded wire. For example, FIG. 1 shows a wire twisting machine for a seven-strand wire. That is, a rotating tube 1 is placed on a guide roller, and within the tube there are six cradles 2 stationary in space, numbered No. 1 to No. 6 from the drawer side, and a bobbin 3 on which a wire is wound. Attach. A fixed supply bobbin 4 is placed behind the last end of the rotary tube, and the wire is also wound around it. The strands wound around each bobbin pass through a hole 7 in the shaft supporting the cradle of the rotary tube 1, are drawn out along the inner wall to the tip of the tube, and are twisted through a batten 8 to become a stranded wire. If the wire is wound around the supply bobbin, the straightness of the wire will be affected accordingly, so it is desirable that the diameter of the bobbin is large. However, if the diameter of the bobbin in the tube is increased, the diameter of the tube itself must be increased, which reduces the number of rotations of the tube, that is, the speed of twisting. It is therefore disadvantageous to increase the diameter of the bobbin within the tube. On the other hand, the outer bobbin at the end of the tube can be made larger in diameter. In general, by preforming the outer wires of the stranded wire through a preform roller just before they are twisted through the batten 8, the wire curl can be reduced, and the linearity of the stranded wires is less affected. . Therefore, the strands 1 wound around six small diameter bobbins installed inside the tube.
1 is used for the outer strand of the stranded wire, and the strand 12 wound around a fixed supply bobbin with a large diameter provided at the rear end of the tube is usually used for the center line of the stranded wire. In this case, the central wire 12 wound around the fixed supply bobbin 4 passes through a straightening roll 13 for straightening to improve its straightness, enters the tube through the center hole 5 of the shaft at the rear end of the tube, and moves along the inner wall of the tube. Then, it is pulled out through the center hole 6 of the batten 8 and becomes the center strand of the stranded wire. Although this central strand 12 uses a bobbin with a large diameter, it still has some curls, so it is necessary to line up a large number of rolls in the right angle direction and pass the strand through the straightening roll 13, which straightens the strand to ensure a sufficient straightening effect. If the wire is bent strongly in the straightening roll in order to make it straight, the pull-out resistance becomes large, and the wire is bent in the tube as shown in the figure, resulting in new wire curls. It is not possible to make stranded steel wire.

Unlike the tubular type wire twisting machine described above, a skip type wire twisting machine as shown in FIG. 2 is also used. This wire twisting machine has an arc-shaped skip 9 at a symmetrical position between the bearings at both ends of each cradle, rotating on the outside of the cradle, instead of the tubes of the tubular type wire twisting machine, and the steel wire is passed through the inside of the arc-shaped skip 9. The stranded wire is manufactured by rotating the skip while moving the wire. Skip-type wire stranding machines are mainly used for twisted wires made of copper, aluminum, etc. for electric wires, or for crossing wire ropes, which are made of flexible materials, and are not used for high-strength thick wires like PC steel stranded wires. It has not been done. One reason for this is that steel pipes are usually used for skips, but they are lower in strength than tubes and do not have the strength to withstand the large tension caused by thick wires.Furthermore, the wires that pass through each skip in sequence have a wavy shape. As the wire passes through the pass line, the pull-out resistance of the wire is large, and due to the number of wave crests, there is a difference in passing resistance between the wire in the cradle near the draw-out port and the wire in the far cradle, which causes twisting between each wire. This is caused by variations in tension. In addition, for the same reason as the tubular type, it is common to use the strands of the fixed supply bobbin placed at the rear of the rear end as the center line of the stranded wire, but the resistance of the straight rolls causes repeated wavy passes within the skip. The disadvantage is that the resistance of the line is doubled and sufficient straightness correction cannot be achieved.

In a skip-type wire twisting machine, when the skip rotates at high speed, the steel wire passing through it tends to stretch outward due to the centrifugal force, and when the tension at both ends of the wire and the tension due to this centrifugal force are balanced, the wire is skipped. It does not come into contact with the inner guide roll or guide pipe and appears to be floating in space, minimizing friction with the skip. When the skip is arc-shaped as shown in FIG. 3, this tension is expressed by the following equation.

T=m (WL/2) ² -mw ² Lα/2 (R-r) where T: Tension Kg m: Mass per unit length of wire Kgsu ² /m ² w: Rotational speed Rad/su L: Skip axis distance α: Angle of the skip end with respect to the axis Rad. R: Skip arc radius m r: Turning radius of the skip apex m For example, in the case of a 7-strand stranded wire with an outer diameter of 1/2 inch, the wire diameter is 4.22 mm. L=230cm, R=146cm, r=56
If the wire is stranded at a speed of 600 revolutions/minute using a skip of cm, T = 17 kg. Also 7 with an outer diameter of 0.6 inches
In this twisted wire, the diameter of the strands is 5.05 mm, and when the wire is twisted at a speed of 450 revolutions/minute using the same type of skip-type wire twisting machine as above, the wire will have a T≒14 kg. This fact shows that when the tension of the bobbin is adjusted to be lower than T, the centrifugal force of the wire causes the strands to stick to the outside of the skip, and the tension increases sequentially due to the friction. As it runs in the middle of the inner guide, the resistance decreases and the tension eventually converges to T. When this balanced tension T is reached, the strands pass through the symmetrical skips in a wavy manner, so that there is no change in balance between the skips, and all the strands except for the strands from No. 1 and No. 2 bobbins The tension of the strands from the bobbin is constant, and this fact is a feature of the skip type wire twisting machine. However, in a skip-type wire twisting machine, the strands of the No. 1 cradle do not pass through the skip, and the strands of the No. 2 cradle also pass through only one skip.
1. This feature is not exhibited for the strands of No. 2 cradle.

This invention was made as a result of research into the above facts in order to eliminate the drawbacks of the conventional wire stranding method. A type wire stranding machine is constructed, and a bobbin for the center strand is attached to the No. 2 cradle of the steel wire machine, and the center strand is pulled out through a straightening device provided in the No. 1 cradle, thereby achieving good straightness. A method and apparatus for manufacturing stranded steel wire.

The present invention will be explained in more detail below with reference to the drawings. FIG. 4 shows an embodiment of a tubular type wire stranding machine for producing seven strands of wire according to the present invention. In other words, there are seven cradles 2 in the rotating tube 1, with No. 2 closest to the drawer side.
1 Straightening device 13 for strands in cradle 2-1
has been made. To use this wire twisting machine, the wire is wound around the fixed bobbin 4 installed outside the rear end of the tube 1 and the bobbin 3 installed in the No. 3 to No. 7 cradles 2-3 to 2-7. Pull wire 11 along the inner wall of tube 1 as shown, and connect No.
The strand 12 wound around the bobbin in the cradle 2-2 is pulled out through the straightening device of the No. 1 cradle 2-1, and using this strand as the center line of the stranded wire, the other 6 strands are stranded. 8. Twist around the outer circumference through the twisting die 15, double capstan 1
The stranded wire 14 is drawn by 0. According to this method and wire twisting machine, the pass line from the bobbin to the central strand is straight and there is no resistance other than the straightening device, so the straightening device can work sufficiently to improve the straightness, and No bending is applied to the strands after leaving the device. Furthermore, by pulling the central strand through the side of the twisting opening, the straightness of the strand can be easily adjusted and checked. Therefore, the straightness of the central strand is very good, and a twisted wire with good straightness can be manufactured. Fifth
The figure shows another embodiment of the tubular type wire twisting machine, in which eight cradles are provided inside tube 1, No. 2 cradle on the drawer side is for the center strand, and a straightening device is attached to No. 1 cradle. so that the center wire passes through the straight path line, and the rest
The strands wound around the bobbins of No. 3 to No. 8 cradles are used for the outer periphery of the stranded wire. With this wire twisting machine as well, it is possible to obtain twisted wires with good linearity as in the case of the above embodiment.

FIG. 6 shows a skip type wire twisting machine according to the present invention. That is, arc-shaped skips 9 that rotate on the outside of the cradle are provided at symmetrical positions between the bearings at both ends of the seven cradles 2, and the strands are passed through the skips and twisted by rotating the skips. Manufacture wire. As in the case of the tupler type, wind the center wire 12 around the bobbin of No. 2 cradle 2-2 on the drawer side, and then
The twisting die 15 is pulled out along a straight path line through the straight line correction device 13 provided in -1. The wires of the fixed bobbin 4 on the outside of the rear end of the wire twisting machine and the bobbins 3 in the No. 3 to No. 7 cradles are passed through the skip 9 in a wavy manner and twisted outside the center line. Fig. 7 shows another embodiment of the skip type wire twisting machine, in which eight cradles are provided and the bobbin of No. 8 cradle 2-8 is used in place of the fixed bobbin 4 of the previous embodiment. be. According to this method, as in the tubular type wire twisting machine, the central strand is drawn out through a straight pass line and a straightening device is provided along the way, so even if the resistance of the straightening device becomes large, there is no problem. Straight lines can be sufficiently straightened without any problems, and twisted wires with good straightness can be obtained. Furthermore, even in the case of No. 3 cradle, the strands on the outer periphery of the stranded wire at the rear of No. 3 cradle are
The tension condition is almost the same as that of the strands passing through one skip in a wavy manner, and the tension is almost the same as that of the strands passing through the other 3 to 7 skips in a wavy manner. This also has the effect of creating tension and making the tension of all the outer strands uniform.

As explained in detail above, according to the present invention, the center strand of the stranded wire is placed in the No. 2 cradle on the draw-out side, and the strand is pulled out to the twisting opening with a straight path line through the straightening device provided in the No. 1 cradle. PC steel stranded wire, stainless steel stranded wire,
When used for high-strength steel strands such as galvanized steel strands, it is possible to produce strands with higher straightness than conventional methods and equipment.

[Brief explanation of the drawing]

Figures 1 and 2 are plan views showing the principles of conventional tubular type and skip type wire twisting machines;
The figure is an explanatory diagram showing the influence of centrifugal force on the strands in a skip-type wire twisting machine, and FIGS. 4 to 7 are plan views showing embodiments of the wire twisting machine of the present invention. 1: Tube, 2-1 to 2-8: No.1 to No.8 cradle, 3: Bobbin, 4: Fixed bobbin, 5: Tube rear end shaft hole, 6: Tip shaft hole, 7: Cradle shaft hole, 8: batten, 9: skip, 10: capstan, 11: outer wire, 12: center wire, 1
3: Straightening machine, 14: Twisted wire, 15: Twisting die.

Claims (1)

[Claims] 1. Stationary cradles are arranged in series, and the strands wound around a bobbin installed in the cradle are pulled out while rotating the outer periphery of the cradle on the exit side and twisted to produce a stranded wire. In the method of A method for twisting high-strength steel wires, which is characterized by twisting wires around the outer periphery of a central strand. 2. In a tubular type wire twisting machine, a straightening machine is provided in the first cradle from the drawer side, and the wire wound around the bobbin installed in the second cradle is pulled out to a straight pass line through the straightening machine. A high-strength steel wire stranding machine characterized in that the center strand of the stranded wire is used as the center strand. 3 In a skip type wire twisting machine, a straightening machine is installed in the first cradle from the drawer side, and
A high-strength steel wire stranding machine characterized in that the strands wound around a bobbin installed in the second cradle are pulled out through the straightening machine to a straight pass line to become the center strand of the stranded wire. .