JP2902634B1 - Steel tensioning device - Google Patents

Abstract

Abstract: [PROBLEMS] When tightening a steel material for applying a compressive force to concrete by screwing a nut, if the tension is converted by the tightening torque of the nut, the effect of frictional resistance and the like when rotating the nut is obtained. In some cases, the tension changed. The steel tensioning device is attached to an end of a steel material embedded or inserted into a concrete block, pulls the steel material, and fixes a fixing member screwed to the end of the steel material. A frame to be contacted, a tow bar having one end connected to the end of the steel material penetrating the frame and having a threaded portion on at least the other end outer surface, a rotating mechanism for rotating the fixing member, and an outer surface of the frame. A display device which is detachably attached and displays the tension of the steel material;
A screw member screwed into a screw portion of the towbar projecting from the outer surface of the display device, and the towbar is screwed by rotating the screw member, so that the display on the display device has a desired tension. In this state, the fixing member is fixed by the rotating mechanism.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for prestressing concrete or tightening a concrete block such as a box culvert, for example, when tensioning steel such as high-strength steel, high-tensile steel or PC steel. The present invention relates to a suitably used steel tensioning device.

[0002]

2. Description of the Related Art Conventionally, in a secondary product of a concrete block such as a box culvert, a compressive force, that is, a pre-stress is introduced in order to make a top plate portion and a bottom plate portion resistant to tension. Steel materials such as high-strength steel materials and PC steel materials are used to connect the following products. In such concrete block secondary products,
For example, the prestress is P
C steel is buried or inserted, one end of the PC steel is fixed to the concrete block, and the PC steel is tensioned with a hydraulic jack or the like in a state where a nut is assumed to be attached to the other end, and elastically deformed within the elastic limit. The nut is fixed and introduced when it is extended. Further, for the concrete block tightening connection, a predetermined number of concrete blocks are laid, the PC steel is inserted into the PC steel insertion hole, and the PC steel is similarly tightened with a hydraulic jack or the like. P
When a hydraulic jack is used, the tension of the C steel material is adjusted by setting the hydraulic jack.

[0003] In recent years, instead of a hydraulic jack, a method has been attempted in which a tension member is tensioned by rotating an assumed nut. In this case, the nut is fixed via the fixing plate and the washer, but if the nut is tightened in such a combination, the sliding friction with the washer is large, and the nut may be deformed or damaged. There is. For this reason, in such a method, a sliding friction reducing member, for example, a thrust bearing washer is used instead of the washer to reduce the sliding friction between the nut and the fixing plate during the fixing operation. Since the sliding friction is reduced by the sliding friction reducing member, the nut is tightened using a nut runner, an impact wrench, or the like.

[0004]

In the apparatus using the above-mentioned sliding friction reducing member, the tension of the steel material is adjusted by the torque when tightening the nut. That is, the tension is converted from the torque required when tightening the nut. A torque value is set in a nut runner or an impact wrench, and the nut is rotated at the same torque value until the set torque value is reached to tension the PC steel. Things.

However, even in a case where a plurality of PC steel materials imparting the same tension are rotated with the same torque value, the frictional resistance between the pull rod and the nut and the amount of lubricating oil applied to a threaded portion thereof are increased. In some cases, the tension applied to each PC steel material differs due to the influence of the change in frictional resistance due to the number of times the thrust bearing washers are used and the like. For example, when the frictional resistance between the pull rod and the nut is large, even if the nut is rotated to the set torque value, the torque corresponding to the frictional resistance is insufficient, so that the tension applied to the PC steel material is reduced. There is. As a result, even if a torque value corresponding to the tension is set, a difference may occur in the amount of prestress introduced.

An object of the present invention is to solve such a problem.

[0007]

In order to achieve the above object, the present invention takes the following measures. That is, the steel material tensioning device according to the present invention is configured such that a display device for displaying the tension of the steel material is detachably attached to the outer surface of the frame attached to the concrete block, and the tension member is protruded from the outer surface of the display device. It is configured to rotate a screw member screwed to the tow bar connected to the end to advance the tow bar. Then, the tension member is pulled by the screwing of the tow bar until the tension displayed by the display device becomes a desired tension, and when the towing is completed, the fixing member is fixed by the rotating mechanism.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a steel material tensioning device which is attached to an end of a steel material embedded or inserted into a concrete block, pulls the steel material, and fixes a fixing member screwed to the end. A frame attached to the concrete block, a tow bar penetrating the frame, one end of which is connected to the end of the steel material and having a threaded portion on at least the other end outer surface, and a rotation for rotating the fixing member A mechanism, a display device that is detachably attached to the outer surface of the frame and displays the tension of the steel material, and a screw member that is screwed to a screw portion of a towbar projecting from the outer surface of the display device. A steel tensioning device characterized by rotating a member to screw a tow bar and fixing a fixing member by a rotation mechanism in a state where a display on a display device has a desired tension.

With this configuration, when the screw member is rotated to pull the steel, the display device displays the tension applied to the steel according to the degree of the pull.
That is, the display device immediately displays the tension of the steel material being pulled, and does not apply the tension to the steel material by rotating the screw member based on the torque value calculated from the desired tension. Therefore, even when the frictional resistance between the screw member and the tow bar affects the torque for rotating the screw member, a desired tension can be applied to the steel material. In addition, since the tow bar is screwed by the rotation of the screw member to tow the tendon material, the towing operation can be facilitated without requiring skill.

[0010] As the steel material in the present invention, for example, PC
Steel rod, unbonded PC steel rod, PC steel stranded wire, unbonded PC steel stranded wire, FRP tendon made by solidifying fiber of glass, carbon, aramid, etc. with epoxy resin, high-strength steel or high-strength rebar, high-strength deformed Reinforcing bars (for example, Malver having a tensile strength of 70 kgf / mm ² or more: manufactured by Induction Hot Melting Co., Ltd.) and the like. For high-strength steel or high-strength rebar, the tensile strength is 440-1.
Those having 200 N / mm ² are preferred.

An example of the display device is an axial force meter.
The axial dynamometer may be, for example, one that detects the pressure applied between the frame and the screw member as a hydraulic pressure, detects the pressure, and displays the tension based on the hydraulic pressure. Alternatively, the pressure may be electrically detected by, for example, a strain gauge or a load cell, and the tension may be displayed based on a change in output voltage. Further, a predetermined tension may be set using the output voltage, and the operation of the electric nut runner or the like for rotating the screw member when the predetermined tension is reached may be stopped.

As a specific mode of such a steel material tensioning device, a fixing member is formed of a nut, and a rotating mechanism includes a cylindrical portion fitted to the nut, and a driving operation for rotating the cylindrical portion in one direction. Is preferably provided. Further, the display device may further include a sliding friction reducing member detachably attached to an outer surface of the display device and a screw member abutting on the outer surface. With this configuration, the screw member can be rotated without difficulty. Moreover, since the sliding friction reducing member is detachably attached to the outer surface of the display device, it is not embedded in the concrete block,
Can be used repeatedly. For this reason, the production cost of the concrete block can be reduced. Further, the size can be reduced as compared with a hydraulic jack or the like, the handling can be easily performed, and the working time from mounting to completion of fixing can be reduced.

In addition, if the rotating mechanism is a ratchet wrench and the sliding friction reducing member is a thrust bearing washer, the operation up to fixing the fixing member can be facilitated. In order to facilitate the handling, it is preferable that the rotating mechanism is integrally rotatably mounted in the frame. By integrating the rotating mechanism such as the ratchet wrench in the frame in this manner, the attachment of the frame and the setting of the rotating mechanism can be performed at the same time, so that the working efficiency is improved and the working time is reduced. Can be.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a steel tensioning apparatus 100 according to this embodiment.
FIG. 1 is a perspective view showing a state in which an unbonded PC steel rod 2 as a steel material embedded or inserted into a precast box culvert (hereinafter abbreviated as “culvert”) 1 as a concrete block. The culvert 1 is widely used in the field and has a box shape including a bottom plate 1A, side walls 1B, and a top plate 1C. In order to introduce prestress, the bottom plate 1A and the top plate 1C have a plurality of unbonded PC steel rods 2 having one end fixed on one outer surface side and having the end buried in the through hole 1a. And a recessed portion 1b is provided so as to be buried or inserted in the through hole and communicate with the through hole 1a and open to the other outer surface. The other end of the unbonded PC steel bar 2 protrudes by a predetermined length into the recessed portion 1b.
The nut 5 and the like are stored. At both ends of the unbonded PC steel rod 2, male threads 2a are formed.

As shown in FIGS. 2 to 5, the steel tensioning device 100 has a cylindrical portion fitted to a PC nut 5 temporarily attached to one end of an unbonded PC steel bar 2 via a fixing plate 3 and a washer 4. A ratchet wrench 6 serving as a rotating mechanism having 6a;
A reaction force plate 7 as a frame in which a ratchet wrench 6 is integrally mounted inside, and an axial force meter as a display device detachably mounted on the outer surface of the reaction force plate 7 and indicating the tension of the unbonded PC steel bar 2. M, a thrust bearing washer 8 as a sliding friction reducing member detachably attached to the outer surface of the axial force meter M, and a ratchet wrench 6 and a reaction force plate 7, one end of which passes through the unbonded PC steel rod 2. The pull rod 9 is provided with a pull rod 9 which is a towbar screwed to the end, and a tension nut 10 which is a tension screw member which is screwed to the other end of the pull rod 9.

The axial force meter M has a pressure-sensitive portion M1 having an opening through which a pull rod 9 can penetrate in the center of an elastically deformable hollow annular body, and a display mounted upright on the upper surface of the pressure-sensitive portion M1. It comprises a barrel M2, a cover M3 for protecting the top and back surfaces of the meter M2, and a handle M4 fixed to the outer surface of the cover M3. The axial force meter M has an unfilled PC steel rod 2 in which oil is filled in the pressure sensitive portion M1.
Is tensioned, the pressure-sensitive portion M1 is compressed and the internal oil pressure changes, and the meter M2 displays the tension applied to the unbonded PC steel bar 2 based on the change in the oil pressure. A tension nut 10 is provided on the front wall M1a of the pressure sensing portion M1.
Reaction wall M5 when an electric nutrunner is used to rotate the motor
Is protruding.

The ratchet wrench 6 is provided with the cylindrical portion 6a described above.
And a drive operation unit 6c which has a built-in ratchet mechanism which is attached to the other end of the tube unit 6a and rotationally drives the tube unit 6a in one direction, and which has an operation lever 6b on the outer side surface. The inside of one end of the cylindrical portion 6a is formed in a hollow shape having a plurality of rectangular recesses on an inner peripheral surface thereof which are selectively engaged with the corners of the PC nut 5 so as to be fitted to the PC nut 5. . The drive operation section 6c has a through hole 6d at the center thereof, through which the pull rod 9 is inserted.

The reaction force plate 7 has a cylindrical shape, and has therein a storage portion 7a having an inside diameter substantially the same as the opening of the concave portion 1b of the culvert 1, and a front surface parallel to the outer surface of the culvert 1. An insertion hole 7c through which the pull rod 9 is inserted is provided at the center of the wall 7b. The storage portion 7a is closed by a ratchet wrench mounting cover 7f so as to be openable and closable, and the drive operation portion 6c of the ratchet wrench 6 is rotatably stored therein. The drive operation unit 6c includes a lever 6
b is attached, corresponding to the lever 6b,
An operation window 7e for the lever 6b is provided on a side wall 7d of the reaction force plate 7.
Is provided. The operation window 7e is notched at an angle of about 90 ° in a circumferential direction of a central axis perpendicular to the front wall 7b of the reaction force plate 7.

A thrust bearing washer 8 is detachably mounted on the outer surface of the front wall M1a of the axial force meter M by a housing 8a. The thrust bearing washer 8 is rolled into a pair of ring plates 8b accommodated in the housing 8a, opposed grooves 8c provided continuously on the opposed surfaces of the ring plates 8b, and respective opposed grooves 8c. And a ball 8d to be freely held. Ring plate 8
b has an opening 8e in the center thereof, for example, one turn larger than the outer diameter of the pull rod 9. The housing 8a has an opening 8f so that the tension nut 10 is in close contact with the ring plate 8b.

The pull rod 9 is made of a round bar member having a high tensile strength, such as a PC steel bar, and a tension nut 10 is screwed into a portion protruding from the thrust bearing washer 8 in a state where the steel material tension device 100 is mounted. It is set to be long enough. An internal thread 9a is formed inside one end thereof so that the unbonded PC steel rod 2 is screwed. The female screw 9a is inserted into the unbonded PC steel bar 2 to temporarily fix the PC nut 5 so that the female screw 9a is screwed into the unbonded PC steel bar 2 with a sufficient length.
It is formed so as to have a length sufficient to be screwed with almost the entire length up to the nut 5. Then, in order to ensure the strength, the female screw 9a is not formed with a length that reaches the vicinity of the other end of the pull rod 9. At least on the outer peripheral surface of the other end, a screw 9b is formed corresponding to the tension nut 10. In this way, if the screw 9b is formed only on the other end side, one end on which the female screw 9a is formed can be easily determined, and when the pull rod 9 is screwed to the unbonded PC steel bar 2, Work efficiency can be improved. The male screw 9b may be formed over the entire length of the outer peripheral surface of the pull rod 9.

In such a configuration, for example, the top plate 1C
When prestress is introduced into the culvert 1, an unbonded PC steel rod 2 is embedded or inserted into the through hole of the culvert 1, one end is fixed with a nut via a fixing plate and a washer (not shown), and the other end is a concave portion. A PC nut 5 is tentatively attached via a fixing plate 3 and a washer 4 in 1b. At the other end of the unbonded PC steel rod 2, the female screw 9a of the pull rod 9 is screwed to the unbonded PC steel rod 2, and the pull rod 9 is screwed. The pull rod 9 is screwed by a predetermined length set in advance. If screwing is insufficient, unbonded PC steel rod 2
When tension is applied, problems such as the pull rod 9 coming off may occur.

Next, the steel rod tensioning device 100 is attached to the top plate 1C by passing the pull rod 9 through the central opening of the steel rod tensioning device 100. At this time, depending on the direction of the PC nut 5, the cylindrical portion 6 a of the ratchet wrench 6
May not be fitted, the lever 6b of the ratchet wrench 6 is operated to rotate the cylindrical portion 6a, and the PC nut 5
And the direction of the cylindrical portion 6a are matched, and the cylindrical portion 6a is connected to the PC nut 5 until just before the tip of the cylindrical portion 6a contacts the washer 4.
To fit. In this state, the other end of the pull rod 9 protrudes from the thrust bearing washer 8. A tensioning nut 10 is screwed into the other end of the protrusion, and the screw is advanced until it comes into contact with the thrust bearing washer 8.

After screwing the tension nut 10 onto the pull rod 9, for example, an electric nut runner is attached to the tension nut 10, and the tension nut 10 is rotated to release the unbond P.
The C steel bar 2 is towed. Tension is tension nut 1
It is determined according to the screwing distance of 0. When towing is started, tension is gradually applied to the axial force meter M with an increase in the screwing distance, and the tension applied to the unbonded PC steel bar 2 during towing is immediately indicated to the meter M2. You. Since the meter M2 is mounted facing outward, the pointer can be checked while using the electric nut runner, that is, the tension can be read directly. Therefore, if the rotation of the tension nut 10 is stopped when the indication of the meter M2 becomes the target tension, a predetermined tension is applied to the unbonded PC steel rod 2. In this case, the work time can be shortened if the tightening is adjusted at a stroke until the tension becomes almost a predetermined value while watching the meter M2, and then the tightening is adjusted by gradually operating the electric nut runner while watching the instruction of the meter M2. Can be.

Since the tensioning nut 10 is in contact with the thrust bearing washer 8, the tensioning nut 10 can be rotated with almost no sliding frictional resistance against the axial force meter M. When a predetermined tension is applied to the unbonded PC steel bar 2, a considerable compressive force is applied to the thrust bearing washer 8. Therefore, if the ball is used repeatedly, the ball 8d may be worn and the rotation of the tension nut 10 may not be smooth. When such a symptom occurs, the housing 8a may be removed from the axial force meter M, and the thrust bearing washer 8 may be replaced. Note that an impact wrench may be used instead of the electric nut runner.

When the tightening of the tensioning nut 10 is completed, the unbonded PC steel bar 2 is elastically deformed and expanded within its elastic limit, so that the PC nut 5 moves in the direction of the reaction force plate 7 in the cylindrical portion 6a. While maintaining this state, that is, in a state where tension is applied to the unbonded PC steel rod 2, the PC nut 5 is fixed by operating the lever 6b of the ratchet wrench 6. The ratchet wrench 6 rotates the cylindrical portion 6a only in one direction by the ratchet mechanism in the drive operation section, so that the PC nut 5 can be easily tightened.

When the fixing of the PC nut 5 is completed, the tension nut 10 is loosened, and the pull rod 9 is loosened while the tension nut 10 is screwed, and is removed from the unbonded PC steel bar 2. Thereafter, the steel tensioning device 100 is pulled away from the culvert 1 to pull out the PC nut 5 from the cylindrical portion 6a, and the tensioning operation is completed. Thus, Unbond PC
Since the tension work of the steel rod 2 can be performed while checking the tension nut 10 with the indication of the axial force meter M, the work can be performed extremely easily without skill. Further, since the relatively expensive thrust bearing washer 8 is detachably attached to the outer surface of the axial force meter M, the unbonded PC steel rod 2
Each time the thrust bearing washer 8 is used as a substitute for the washer at the time of fixing, it is not necessary to bury the thrust bearing washer 8 in the recessed portion 1b. Prestress can be applied. Moreover, since the thrust bearing washer 8 can be removed for maintenance, the tensioning nut 10 can be rotated in the best condition at all times, and the tensioning operation can be reliably completed with simple operation contents. Further, if the ratchet wrench 6 is integrally attached to the reaction force plate 7 as in this embodiment, when the steel tensioning device 100 is mounted on the unbonded PC steel rod 2, the operation sequence does not matter. Therefore, the working time can be reduced.

The present invention is not limited to the embodiment described above. In the above-described embodiment, the tensioning operation of the steel material when the prestress is introduced into the concrete block has been described.However, the present invention is also applicable to the tensioning operation of the steel material for so-called vertical tightening, which connects the concrete block with the steel material. Good. In the above embodiment,
Although the example using the thrust bearing washer 8 was explained, instead of the thrust bearing washer 8, the area where the tension of the unbonded PC steel bar 2 is sufficiently transmitted to the axial force meter M when the tension nut 10 is tightened is described. A common flat washer may be used. In this case, if grease or the like is applied to reduce the frictional resistance between the tensioning nut 10 and the flat washer, the rotation becomes smooth and the work can be facilitated. The tensioning work may be performed by directly attaching the tensioning nut 10 to the outer surface of the small wall M2 of the axial force meter M without using a flat washer.

The ratchet wrench 6 may be formed separately from the reaction force plate 7. In addition, the configuration of each unit is not limited to the illustrated example, and various modifications can be made without departing from the spirit of the present invention.

[0029]

As described above, according to the present invention, when the screw member is rotated, the tension of the steel material is displayed following the rotation by the display device, so that it is easy to confirm the tension. The desired tension can be applied to the steel material without depending on the frictional resistance between the screw member and the towbar, the amount of the lubricating oil, and the like. In addition, since the tow bar is screwed by the rotation of the screw member to tow the tendon material, the towing operation can be facilitated without requiring skill.

The fixing member comprises a nut, and the rotating mechanism comprises
If it is provided with a tubular portion fitted to the nut, and a drive operation unit for rotating the tubular portion in one direction, at low cost,
In addition, the size can be reduced. Further, if the display device further includes a sliding friction reducing member detachably attached to the outer surface of the display device and the screw member abuts on the outer surface, the screw member can be rotated without difficulty. Moreover, since the sliding friction reducing member is detachably attached to the outer surface of the display device, it can be used repeatedly without being embedded in the concrete block. For this reason,
The manufacturing cost of the concrete block can be reduced. Further, the size can be reduced as compared with a hydraulic jack or the like, the handling can be easily performed, and the working time from mounting to completion of fixing can be reduced.

In addition, if the rotating mechanism is a ratchet wrench and the sliding friction reducing member is a thrust bearing washer, the operation up to fixing the fixing member can be facilitated. Further, if the rotating mechanism is integrally mounted rotatably in the frame, the attachment of the frame and the setting of the rotating mechanism can be performed at the same time, so that the working efficiency is improved and the working efficiency is improved. Time can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a use state according to an embodiment of the present invention.

FIG. 2 is a perspective view of the embodiment in use.

FIG. 3 is a front view of the embodiment when a pull rod and a tension nut are removed.

FIG. 4 is an exploded perspective view of the embodiment.

FIG. 5 is an enlarged sectional view of a main part showing a use state of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Concrete box culvert 2 ... Unbonded PC steel bar 5 ... PC nut 6 ... Ratchet wrench 7 ... Reaction force plate 8 ... Thrust bearing washer 9 ... Pull rod 10 ... Tension nut M ... Axial force meter

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Akihiko Iwasaki 1-16-5 Omorinishi, Ota-ku, Tokyo Inside Tonichi Works, Ltd. (56) References JP-A-4-208403 (JP, A) ( 58) Surveyed field (Int.Cl. ⁶ , DB name) E04G 21/12 104 B66F 19/00 E03F 3/04

Claims (6)

(57) [Claims] A steel tensioning device mounted on an end of a steel material embedded or inserted into a concrete block to pull the steel material and fix a fixing member screwed to the end of the steel material. A frame to be attached, a tow bar penetrating the frame, one end of which is connected to the end of the steel material and having a screw portion on at least the other end outer surface, a rotating mechanism for rotating the fixing member, and an outer surface of the frame A display device detachably attached to the display device for displaying the tension of the steel material, and a screw member screwed into a screw portion of a tow bar protruding from an outer surface of the display device, and rotating the screw member to tow. A steel tensioning device wherein a rod is screwed and a fixing member is fixed by a rotating mechanism in a state where a display on a display device has a desired tension. 2. The steel tensioning device according to claim 1, wherein the display device comprises an axial force meter. 3. The fixing member comprises a nut, and the rotating mechanism comprises
2. The apparatus according to claim 1, further comprising: a tubular portion fitted to the nut; and a drive operation unit configured to rotate the tubular portion in one direction.
Or the steel tensioning device according to 2. 4. The steel material tensioning device according to claim 1, further comprising a sliding friction reducing member detachably attached to an outer surface of the display device and a screw member abutting on the outer surface. 5. The rotating mechanism comprises a ratchet wrench,
The steel tensioning device according to claim 4, wherein the sliding friction reducing member is a thrust bearing washer. 6. The system according to claim 1, wherein the rotating mechanism is integrally mounted so as to be rotatable in the frame.
The steel material tensioning device according to 3, 4, or 5.