JP2995166B2 - Tendon tensioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tendon tensioning device which is preferably used when prestressing concrete or tensioning a tensioning member such as a box culvert for tightening a concrete block.

[0002]

2. Description of the Related Art Conventionally, in a concrete block secondary product such as a box culvert, when it is necessary to make a top plate portion and a bottom plate portion and the like strong in tension, a tension member having a traction force is provided in a concrete structure. Buried or inserted,
It is known that the traction force is transmitted to a facing fixing plate to introduce prestress into a concrete structure. The introduction of prestress is generally performed by embedding or inserting a tendon in a concrete block, fixing one end of the tendon to the concrete block, and assuming that a nut is attached to the other end of the hydraulic jack. The tension member is pulled by, for example, is elastically deformed within the elastic limit, and the nut is fixed when it is extended.

[0003] In recent years, instead of the hydraulic jack, a method has been attempted in which a prestressed nut is rotated to rotate the nut and use a screw member to advance the tension member. The nut is fixed via the fixing plate and the washer. When the nut is tightened in such a combination, the sliding friction with the washer is large, and the nut may be deformed or damaged. 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]

However, in the above-mentioned method, when the nut is fixed to the thrust bearing washer, the thrust bearing washer is buried in the concrete block instead of the washer. Cannot be used for In other words, in the case of a hydraulic jack, even if the concrete block changes, it can be used repeatedly, while the thrust bearing washer is used to facilitate the work of pulling the tendon, but since it works only as a part after fixing, Cannot be used repeatedly. For this reason, the cost of parts is higher than that of a normal washer, so that the manufacturing cost is increased.

[0005] An object of the present invention is to solve such a problem.

[0006]

In order to achieve the above object, the present invention takes the following measures. That is, the tension member tensioning device according to the present invention rotates the screw member screwed to the tow bar connected to the end portion of the tension member via the sliding friction reducing member on the outer surface of the frame attached to the concrete block. Then, the tension member is pulled, and the fixing member is fixed by the rotating mechanism when the pulling is completed.

With such a configuration, the screw member is rotated via the sliding friction reducing member, so that the screw member can be rotated without difficulty. The tow rod is screwed by the rotation of the screw member, and the tension member is towed, so that the towing operation can be facilitated. 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.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a tension member which is attached to an end of a tension member embedded or inserted into a concrete block, pulls the tension member, and fixes a fixing member screwed to the end. A tensioning device, a frame attached to the concrete block, a tow bar having one end connected to the end of the tension member and having a threaded portion on at least the other end outer surface, penetrating the frame, and the fixing member. A rotating mechanism for rotating, and a screw member screwed to a screw portion of the tow bar via a sliding friction reducing member detachably attached to an outer surface of the frame, and rotating the screw member. The tensioning member tensioning device is characterized in that the tension member is screwed forward to hold the tensioning member in a state where a predetermined tension is applied to the tensioning member and the fixing member is fixed by the rotating mechanism.

According to such a configuration, if the tow bar is connected to the end of the tendon and the screw member is rotated to screw the tow bar, the tendon is tensioned in accordance with the screwing distance. . Therefore, the work of tensioning the tension member is simplified and can be performed without skill. Since the screw member is rotated via the sliding friction reducing member attached to the outer surface of the frame, the screw member can be rotated without requiring a large amount of labor. Moreover, since the sliding friction reducing member is attached to the outer surface of the frame, it can be used repeatedly without being embedded in the concrete block. For this reason, the production cost of the concrete block can be reduced.

As a specific mode of such a tensioning member tensioning device, the fixing member is formed of a nut, and a rotating mechanism includes a cylindrical portion fitted to the nut and a drive for rotating the cylindrical portion in one direction. The one provided with an operation unit is preferable. Further, it is more preferable that the rotating mechanism is a ratchet wrench and the sliding friction reducing member is a thrust bearing washer.

In order to facilitate the handling, it is preferable that the rotating mechanism is integrally mounted so as to be rotatable in the frame. In this way, by integrating a rotating mechanism such as a ratchet wrench in the frame, the attachment of the frame and the setting of the rotating mechanism can be performed simultaneously,
Work efficiency is improved, and work time can be reduced.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a tendon tensioning device 10 of the present embodiment.
FIG. 1 is a perspective view showing a state in which an unbonded PC steel rod 2 as a tendon material embedded or inserted in a precast box culvert (hereinafter abbreviated as “culvert”) 1 as a concrete block. Culvert 1
Is widely used in the field,
, A side wall 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 and then having the end embedded.
Is buried or inserted, and a concave portion 1b is provided so as to open to the other outer surface. The other end of the unbonded PC steel bar 2 protrudes by a predetermined length in the concave portion 1b, and a nut 5 serving as a fixing member is housed therein. At both ends of the unbonded PC steel rod 2, male threads 2a are formed.

The tensioning device tensioning device 100 is a ratchet as a rotating mechanism having a cylindrical portion 6a fitted to a PC nut 5 which is temporarily attached to one end of an unbonded PC steel bar 2 via a fixing plate 3 and a washer 4. A wrench 6 and a reaction force plate 7 serving as a frame in which a ratchet wrench 6 is integrally mounted.
A thrust bearing washer 8, which is a sliding friction reducing member detachably attached to the outer surface of the reaction force plate 7, and a ratchet wrench 6 and one end of the reaction force plate 7 which penetrate the reaction force plate 7, and one end of which is the end of the unbonded PC steel rod 2. The pull rod 9 is a tow rod screwed to the portion, and a tow nut 10 is a tow screw member screwed to the other end of the pull rod 9.

The ratchet wrench 6 is provided with the above-mentioned cylindrical portion 6a.
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 driving operation section 6c of the ratchet wrench 6 is rotatably stored in the storage section 7a. Since the lever 6b is attached to the drive operation section 6c, an operation window 7e for the lever 6b is provided on the side wall 7d of the reaction force plate 7 corresponding to the lever 6b. Operation window 7e
In the circumferential direction of the central axis perpendicular to the front wall 7b of the reaction force plate 7,
Notched at an angle of about 90 °.

A thrust bearing washer 8 is detachably mounted on the outer surface of the front wall 7b of the reaction force plate 7 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. The ring plate 8b has an opening 8e in the center thereof, for example, one turn larger than the outer diameter of the pull rod 9. Housing 8a
Has an opening 8f so that the towing 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 pulling nut 10 is screwed into a portion protruding from the thrust bearing washer 8 with the reaction force plate 7 attached. 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 through the unbonded PC steel bar 2 so that the female screw 9a is screwed into the unbonded PC steel bar 2 with a sufficient length.
After the C nut 5 is temporarily fixed, the C nut 5 is formed to have a length sufficient to be screwed with almost the entire length from the end to the PC 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 at the other end, a screw 9b is formed corresponding to the pulling 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 pull rod 9 is connected to the front wall 7 of the reaction force plate 7.
b through the thrust bearing washer 8 and the reaction force plate 7
To the culvert 1. At this time, the cylindrical portion of the ratchet wrench 6 may not fit into the PC nut 5 depending on the direction of the PC nut 5.
By operating the lever 6b, the cylinder 6a is rotated so that the directions of the PC nut 5 and the cylinder 6a coincide with each other, so that the tip of the cylinder 6a contacts the washer 4. In this state, the other end of the pull rod 9 protrudes from the thrust bearing washer 8. The pulling nut 10 is screwed onto 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 traction nut 10, for example, a nut runner is attached to the traction nut 10, a predetermined torque is applied to the traction nut 10, the traction nut 10 is rotated, and the unbonded PC steel rod 2 is rotated. Implement towing. The traction force is determined according to the screwing distance of the traction nut 10.
Therefore, set the nut runner torque,
If the towing nut 10 is rotated until the torque is reached,
The pull rod 9 is screwed outward from the inside of the concave portion 1b to apply a predetermined tension to the unbonded PC steel bar 2. Since the towing nut 10 is in contact with the thrust bearing washer 8, the towing nut 10 can be rotated while the sliding friction resistance against the reaction force plate 7 is almost zero. 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 used repeatedly, the ball 8d may be worn and the rotation of the traction nut 10 may not be smooth. When such a symptom occurs, the housing 8a may be removed from the reaction plate 7 and the thrust bearing washer 8 may be replaced. Note that an impact wrench may be used instead of the nut runner. In addition, while controlling the torque of the nut runner, the unbond P when the predetermined torque is reached is obtained.
It is desirable to measure the elongation length of the C steel rod 2 and manage the elongation length to check the tension based on the elongation length.

When the tightening of the towing nut 10 is completed, the unbonded PC steel bar 2 is elastically deformed and stretched 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 traction nut 10 is loosened, and the pull rod 9 is loosened while the traction nut 10 is screwed and removed from the unbonded PC steel bar 2. Thereafter, the reaction force plate 7 is pulled away from the culvert 1 in order to pull out the PC nut 5 from the cylindrical portion 6a, and the tensioning operation is completed. As described above, the tensioning work of the unbonded PC steel bar 2 only needs to rotate the traction nut 10 with a predetermined torque, so that the work can be performed extremely easily without skill. In addition, since the relatively expensive thrust bearing washer 8 is attached to the outer surface of the reaction plate 7, it is not embedded in the recessed portion 1b for each unbonded PC steel rod 2, and therefore, can be used repeatedly. As a result, the prestress can be applied to the unbonded PC steel bar 2 at a lower cost than when the thrust bearing washer 8 is used as a substitute for the washer at the time of fixing.
Moreover, since the thrust bearing washer 8 is detachably attached to the reaction force plate 7, the towing nut 10 can be always rotated in the best condition, and the tensioning operation can be completed with simple operation contents. it can. If the ratchet wrench 6 is integrally attached to the reaction force plate 7 as in this embodiment, the tension member tensioning device can be unbonded PC.
The work time can be shortened because the work order can be set irrespective of the work order when the steel rod 2 is mounted.

The present invention is not limited to the embodiment described above. In the above embodiment, the tensioning work of the tendon when the prestress is introduced into the concrete block has been described.However, the present invention is applied to the tensioning work of the tendon for the so-called vertical tightening for connecting the concrete blocks by the tendon. There may be. Further, the ratchet wrench 6 may be formed separately from the reaction force plate 7.

In addition, the configuration of each section is not limited to the illustrated example, and various modifications can be made without departing from the spirit of the present invention.

[0025]

As described above, according to the present invention, since the sliding friction reducing member is detachably attached to the outer surface of the frame, it can be used repeatedly without being embedded in each concrete block. For this reason, the production cost of the concrete block can be reduced. In addition, when the sliding friction reducing member is worn, by replacing it, the screw member can always be rotated in the best condition, and the operation can be performed safely. Furthermore, by managing the torque for rotating the screw member,
Tension can be fine-tuned. In addition, since the device configuration is simpler than that of a hydraulic jack or the like, the device can be manufactured at a low cost, and can be easily attached to the tendon, so that the operation time can be significantly 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.

FIG. 3 is a front view of the embodiment.

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 plate 8 ... Thrust bearing washer 9 ... Pull rod 10 ... Towing nut

Claims (4)

(57) [Claims] 1. A tendon tensioner mounted on an end of a tendon embedded or inserted into a concrete block to pull the tendon and fix a fixing member screwed to the end thereof. A frame attached to the concrete block, a tow bar penetrating the frame, one end of which is connected to the end of the tension member and having a threaded portion on at least the other end outer surface, and a rotating mechanism for rotating the fixing member And a screw member screwed to the screw portion of the towbar via a sliding friction reducing member detachably attached to the outer surface of the frame, and the towbar is screwed by rotating the screw member. A tensioning member tensioning device, wherein the tensioning member is fixed by a rotating mechanism while maintaining a state where a predetermined tension is applied to the tensioning member. 2. A fixing member comprising a nut, and a rotating mechanism comprising:
The tension member tensioning device 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. 3. The rotating mechanism comprises a ratchet wrench,
The tension member tensioning device according to claim 2, wherein the sliding friction reducing member is a thrust bearing washer. 4. The tensioning member tensioning device according to claim 2, wherein the pivoting mechanism is integrally and rotatably mounted in the frame.