JP2004052237A - Pc steel wire tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a PC steel wire tensioner for largely reducing manufacturing cost, and shortening work time. <P>SOLUTION: This PC steel wire tensioner 21 has a plurality of steel wire tensioning jacks 23 having a hydraulic cylinder 25 for holding an end part of a steel wire W used for prestressed concrete and towing and tensioning this end part and a tension maintaining device 27 for holding a tension state of the steel wire W by the hydraulic cylinder 25 by rotating a nut 51 threadedly engaged with the end part of the steel wire W and first and second forms 81 and 85 for mutually holding the plurality of these steel wire tensioning jacks 23 in a parallel state. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a PC steel wire tensioning device for tensioning a steel wire used for prestressed concrete with a desired force.
[0002]
2. Description of the Related Art and Problems to be Solved
In recent years, in concrete sleepers, prestressed concrete, which increases strength by applying a compressive force in advance, has been widely used.
[0003]
As such concrete sleepers, for example, those shown in FIGS. 4 to 6 are known. The concrete sleeper 11 has ten PC steel wires 15 in the longitudinal direction of the concrete sleeper body 13 as shown in FIG. These PC steel wires 15 are pre-tensioned and embedded in concrete, and the strength is improved by applying a compressive stress to the crossties in the longitudinal direction.
[0004]
In order to manufacture such a concrete sleeper 11, a hydraulic cylinder for tensioning each of the ten PC steel wires is required. Conventionally, these ten hydraulic cylinders are connected to a PC steel wire 15 as shown in FIG. A PC wire tensioner placed in position was used.
[0005]
However, the number and arrangement of the PC steel wires differ depending on the sleepers to be manufactured. For this reason, it is necessary to design and manufacture the entire PC steel wire tensioning device in each case according to the sleeper to be manufactured, and there is a problem that the manufacturing cost of the PC steel wire tensioning device is increased and the manufacturing period is long.
[0006]
An object of the present invention is to solve the above problems and to provide a PC steel wire tensioning device that can be manufactured at low cost in a short time.
[0007]
[Means for Solving the Problems]
A first feature of the present invention is that a hydraulic cylinder which holds an end of a steel wire used for prestressed concrete and pulls and tensions the steel wire, and a screw member screwed to the end of the steel wire are rotated. A plurality of steel wire tensioning jacks having a tension maintaining device for maintaining the tensioning state of the steel wire by the hydraulic cylinder, and a formwork for holding the plurality of steel wire tensioning jacks in parallel with each other. It is prepared.
[0008]
A second feature of the present invention is that the hydraulic cylinder has a plurality of hydraulic working chambers in which hydraulic pressure acts in the axial direction.
[0009]
A third feature of the present invention is that the tension maintaining device includes a screw pitch measuring device that measures a screw pitch due to rotation of the screw member.
[0010]
A fourth feature of the present invention is that the formwork is provided at each end of the steel wire tensioning jack.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
[0012]
FIGS. 1 and 2 show a PC steel wire tensioning device 21 according to an embodiment of the present invention. The PC wire tensioning device 21 has two steel wire tensioning jacks 23, and the steel wire tensioning jack 23 has a hydraulic cylinder 25 and a tension maintaining device 27.
[0013]
The hydraulic cylinder 25 has a cylindrical cylinder body 29. The cylinder main body 29 is formed in a cylindrical shape, and an end portion 29a opposite to the PC steel wire W is formed in a square cross section. A piston rod 31 penetrates the cylinder body 29. One end of the piston rod 31 is provided with a female screw portion 31a that is screwed to the male screw portion Wa of the PC steel wire W. The other end of the piston rod 31 is disposed so as to protrude from the cylinder body 29. A first piston 33 and a second piston 35 are fitted and fixed to a portion of the piston rod 31 inside the cylinder body 29, respectively. Between the first piston 33 and the second piston 35, a reduced diameter portion 37 inserted in the inner periphery of the cylinder body 29 is provided. A first hydraulic working chamber 39 is formed between the first piston 33 and the cylinder body 29, and a first working oil port 41 for supplying working oil to the first hydraulic working chamber 39 is connected to the cylinder body. 29. A second hydraulic working chamber 43 is formed between the second piston 35 and the reduced diameter portion 37, and a second hydraulic oil port 45 that supplies hydraulic oil to the second hydraulic working chamber 43 is a cylinder. It is formed on the main body 29. As described above, since the hydraulic cylinder 25 has the two hydraulic operating chambers of the first hydraulic operating chamber 39 and the second hydraulic operating chamber 43 in the cylinder main body 29, the diameter of the hydraulic cylinder can be reduced. In addition, the capacity of the hydraulic cylinder can be improved.
[0014]
A spring 47 is provided between the second piston 35 and the cylinder body 29. When no pressure is applied to the first and second hydraulic working chambers 39 and 43, the piston rod 31 is returned to the PC steel wire W side.
[0015]
In such a hydraulic cylinder 25, a tension maintaining device 27 is provided. The tension maintaining device 27 has a nut 51 that is screwed to the male screw portion Wa at the end of the PC steel wire W. The nut 51 is provided with a cylindrical sleeve 55 having a socket portion 53 fitted on the outer periphery of the nut 51. The sleeve 55 is rotatably fitted to one end of the piston rod 31 connected to the PC steel wire W. A first gear 57 is provided on the outer periphery of the sleeve 55 on the side opposite to the PC steel wire W. A second gear 59 is engaged with the first gear 57, and the second gear 59 is fixed to one end of a rotating shaft 61 provided in parallel with the cylinder body 29. The rotating shaft 61 is rotatably supported via a rolling bearing 65 on a gear box 63 provided at one end of the cylinder body 29 on the PC steel wire W side. The other end of the rotary shaft 61 is supported by a slide bearing 67 provided at the other end of the cylinder body 29.
[0016]
A third gear 69 is provided in the middle of the rotating shaft 61. The third gear 69 is engaged with a fourth gear 73 provided on a screw pitch counter 71, and can count the number of rotations of the rotating shaft 61, that is, the number of thread pitches. The rotating shaft 61 is rotated by a driving device (not shown). The driving device rotates the rotating shaft 61, rotates the sleeve 55 via the second gear 59 and the first gear 57, and rotates the nut 51.
[0017]
The two steel wire tensioning jacks 23 configured as described above have their ends opposite to the PC steel wire W fixed by the first formwork 81. A hole 83 is formed in the first mold frame 81 so as to correspond to the square end portion 29a of the cylinder body 29. The end portions of the cylinder bodies 29, 29 of the two steel wire tensioning jacks 23, 23 are formed. 29a, 29a are fixed. A second formwork 85 is attached to the steel wire tension jacks 23 on the gear box 63 side. As described above, the two steel wire tensioning jacks 23 are held in a predetermined positional relationship by the first mold 81 and the second mold 85.
[0018]
Next, the function and operation of the PC steel wire tensioning device 21 will be described by taking as an example a case where the PC steel wire tensioning device 21 is used for manufacturing a post-tension type precast concrete sleeper.
[0019]
First, a concrete sleeper 91 as shown in FIG. 3 is prepared. The concrete sleeper 91 has two through holes 93 that penetrate from one end to the other end and are separated by an interval L. Although an actual concrete sleeper usually uses eight or more PC steel wires, a case in which two PC steel wires are used will be described here to simplify the description.
[0020]
Next, in the PC steel wire tensioning device, the first formwork 81 and the second mold are arranged such that the steel wire tensioning jacks 23 can be arranged and fixed such that the respective piston rods 31 are spaced L from each other. A frame 85 mold is manufactured. Then, the two steel wire tensioning jacks 23 are fixed using the first and second molds 81, 85, and the PC steel wire tensioning device 21 is assembled.
[0021]
Next, the PC steel wires W are inserted into the two through holes 93, 93 of the concrete sleeper 91, respectively. One end of each of the PC steel wires W is fixed to one end of a concrete sleeper (not shown). On the other hand, a male thread Wa is formed at the other end of each PC steel wire, and a nut 51 is screwed into the male thread Wa. Then, the nut 51 is brought into contact with the seat surface 94 of the concrete sleeper 91.
[0022]
In this state, the PC wire tensioning device 21 is mounted on the other end surface 95 of the concrete sleeper 91. Specifically, the male screw portion Wa of the PC steel wire W is screwed into the female screw portion 31a of the piston rod 31 of the PC steel wire tensioning device 21, the socket portion 53 of the sleeve 55 is fitted to the nut 51, and the second The mold 85 is brought into contact with the other end surface 95 of the concrete sleeper 91 and fixed.
[0023]
From this state, the tension work of the PC steel wire W is started.
[0024]
First, hydraulic oil is supplied to the first hydraulic oil port 41 and the second hydraulic oil port 45. Then, the hydraulic oil from the first hydraulic oil port is pressed into the first hydraulic operating chamber 39, and the hydraulic oil from the second hydraulic oil port is pressed into the second hydraulic working chamber 43. Then, the first piston 33 and the second piston 35 are pressed, respectively, and the piston rod 31 is pressed rightward in FIG. Here, since the first hydraulic operating chamber 39 and the second hydraulic operating chamber 43 are arranged side by side in the axial direction, the pressing force is doubled without increasing the outer diameter of the cylinder body 29. be able to. Therefore, the steel wire tension jack 23 itself can be made compact.
[0025]
As described above, by pressing the piston rod 31 rightward, the PC steel wire W having one end fixed to the piston rod 31 is pulled rightward. Then, when the right end of the PC steel wire W moves rightward by a predetermined amount, the pulling of the PC steel wire W is stopped. Here, when the end of the PC steel wire W moves to the right, the nut 51 screwed to the male screw portion Wa also moves to the right, and between the nut 51 and the seat surface 94 of the concrete sleeper 91. Are formed at predetermined intervals.
[0026]
Next, the driving device (not shown) of the tension maintaining device 27 is operated to rotate the rotating shaft 61. The rotation of the rotation shaft 61 is transmitted to the sleeve 55 via the second gear 59 and the first gear 57. Then, the nut 51 fitted to the socket portion 53 is rotated and moved to the left in FIG. 1 so that the nut 51 abuts on the seat surface 94. By doing so, even if the pressure is subsequently released from the hydraulic cylinder 25, the PC steel wire W is maintained in a tensioned state by the nut 51, and the tensioned state is maintained. At this time, the rotation of the rotating shaft 61 is transmitted to the screw pitch counter 71 via the third gear 69 and the fourth gear 73 so that the number of rotations of the nut 51, the number of pitches of the thread, and the like can be counted. It has become.
[0027]
Thereafter, the operation of pulling the PC steel wire W to the right by the hydraulic cylinder 25 and then maintaining the tension of the PC steel wire W by the tension maintaining device 27 is repeated many times. Then, when the PC steel wire W is tensioned to a predetermined tension state, the operation is stopped. After the work is completed, the PC steel wire tensioning device 21 is removed from the concrete sleeper 91. In this way, a compressive force can be constantly applied to the concrete sleeper 91 by the PC steel wire W, and the strength can be improved.
[0028]
As described above, in the PC steel wire tensioning device 21, the hydraulic cylinder 25 that holds the end of the PC steel wire W used for prestressed concrete, pulls it, and tensions it, A steel wire tensioning jack 23 having a tension maintaining device 27 for rotating the nut 51 screwed to the end of the W to maintain the tensioning state of the steel wire W by the hydraulic cylinder 25, and a plurality of the steel wire tensioning jacks 23. Since the first formwork 81 and the second formwork 85 are fitted and held at predetermined positions, even if the arrangement position of the PC steel wire W differs depending on the product, the steel wire tension jack is provided. Any tension work can be dealt with simply by exchanging the first and second molds 81, 85 and the like holding the 23. Therefore, it is not necessary to manufacture a PC steel wire tensioning device for each product, and the manufacturing cost can be greatly reduced. Further, since it is possible to adapt to different tensioning work just by replacing the mold, the working time can be reduced.
[0029]
Also, the hydraulic cylinder 25 has a plurality of first hydraulic operating chambers 39 and second hydraulic operating chambers 43 in which hydraulic pressure acts in the axial direction, so that the hydraulic operating cross-sectional area is increased to improve the operating force. At the same time, the size of the hydraulic cylinder can be reduced. Therefore, the present invention can be applied to a concrete member having a narrow PC steel wire arrangement interval.
[0030]
Furthermore, since the tension maintaining device 27 has the screw pitch counter 71 that measures the screw pitch due to the rotation of the nut 51, the tension state of the PC steel wire can be easily managed.
[0031]
In addition, in the said embodiment, although the case where the PC steel wire tensioning apparatus 21 is used for the manufacture of the post-tension type precast concrete is described, it is not limited to this, and the pre-tension type precast concrete is not required. It can also be applied to the production of concrete products.
[0032]
Further, in the above embodiment, the case where the number of the PC steel wires is two is described, but this is for the convenience of the description. Therefore, by using a PC steel wire tensioning device incorporating a large number of steel wire tensioning jacks 23, it is also possible to simultaneously tension many PC steel wires.
[0033]
In the above embodiment, the manufacture of concrete sleepers is taken as an example. However, the present invention is not limited to this, and any precast concrete product using a plurality of PC steel wires can be used. Applicable.
[0034]
【The invention's effect】
As described above, in the present invention, a hydraulic cylinder that holds an end of a steel wire used for prestressed concrete and pulls and tensions the steel wire, and a screw that is screwed to the end of the steel wire A plurality of steel wire tension jacks having a tension maintaining device for rotating a member to maintain the tension of the steel wire by the hydraulic cylinder, and a mold for holding the plurality of steel wire tension jacks in parallel with each other Since it is equipped with a frame, any tensioning work can be dealt with simply by replacing the formwork that holds the steel wire tensioning jack, even if the PC wire spacing is different depending on the product. . Therefore, it is not necessary to manufacture a PC steel wire tensioning device for each product, and the manufacturing cost can be greatly reduced. Further, since it is possible to adapt to different tensioning work just by replacing the mold, the working time can be reduced.
[Brief description of the drawings]
FIG. 1 is a front view showing a PC steel wire tensioning device according to an embodiment of the present invention.
FIG. 2 is a side view of the PC steel wire tensioning device shown in FIG.
FIG. 3 is a sectional view schematically showing a concrete sleeper to be manufactured.
FIG. 4 is a partially cutaway front view showing a concrete sleeper.
FIG. 5 is a plan view showing a concrete sleeper.
FIG. 6 is a side view showing a concrete sleeper.
[Explanation of symbols]
21 PC steel wire tensioning device 23 Steel wire tensioning jack 25 Hydraulic cylinder 27 Tension maintaining device 39 First hydraulic operating chamber 43 Second hydraulic operating chamber 51 Nut 71 Screw pitch counter 81 First formwork 85 Second formwork

Claims (4)

A hydraulic cylinder that holds an end of a steel wire used for prestressed concrete, pulls it, and tensions the steel wire, and rotates a screw member screwed to the end of the steel wire to rotate the steel wire by the hydraulic cylinder. A plurality of steel wire tension jacks having a tension maintaining device for maintaining a tension state,
A formwork that holds the plurality of steel wire tension jacks in parallel with each other,
A PC steel wire tensioning device comprising: 2. The tensioning device according to claim 1, wherein the hydraulic cylinder has a plurality of hydraulic working chambers in which a hydraulic pressure acts in an axial direction. 3. 3. The PC steel wire tensioning device according to claim 1, wherein the tension maintaining device includes a screw pitch measuring device that measures a thread pitch due to rotation of the screw member. The PC steel wire tensioning device according to any one of claims 1 to 3, wherein the formwork is provided at each end of the steel wire tensioning jack.

Images