JP5656679B2 - Ram chair for fastening device and fastening device provided with the same - Google Patents

Description

  The present invention relates to a ram chair for a fastening device applied to a rotary machine such as a gas turbine or a steam turbine.

  Generally, a turbine casing of a gas turbine or a steam turbine is divided into two parts in the vertical direction, and the turbine casings divided in the vertical direction are fastened to each other by a plurality of vehicle compartment bolts.

  The casing bolt for fastening the turbine casing divided in this way has a large diameter, and an excessive tightening force is required to ensure a prescribed tightening force. In addition, when the vehicle compartment bolt is tightened by an excessive tightening force, the threaded portion of the vehicle compartment bolt may be seized. In order to obtain such an excessive tightening force and to prevent seizure of the threaded portion, the casing bolt is stretched and tightened using a bolt tensioner.

FIG. 4 shows a schematic configuration diagram of the bolt tensioner 100.
A casing bolt 103 is inserted through the flange portion 102 of the turbine casing. A nut 104 is screwed onto the passenger compartment bolt 103 so as to be seated on the flange portion 102 of the turbine casing.

  The casing bolt 103 is provided with a ram chair 110 for fastening the bolt tensioner 100 (hereinafter referred to as a “ram chair”) 110 on the outer periphery of a nut 104 screwed into the casing bolt 103. In addition, a bolt tensioner main body 111 is provided on the outer periphery in the vicinity of the top of the vehicle compartment bolt 103.

The ram chair 110 is provided with one nut tightening window 118 having a long axis in the circumferential direction above a substantially central portion in the axial direction.
The bolt tensioner main body 111 includes a piston 112 provided on the outer periphery above the casing bolt 103 and a cylinder 113 provided on the outer periphery of the piston 112.

  A screw portion (not shown) is provided on the inner peripheral wall of the piston 112 and meshes with a screw portion (not shown) provided on the outer wall of the casing bolt 103 to form a screw engagement portion 105. ing. The outer peripheral wall of the piston 112 has a stepped portion 112a at a lower portion thereof, and can engage with a stepped portion 113a provided at a lower portion of the inner peripheral wall of the cylinder 113.

  An O-ring 114 is provided in the circumferential direction on the outer peripheral wall above the piston 112. An O-ring 116 is provided in the circumferential direction on the inner peripheral wall of the step 113a of the cylinder 113. Thus, when the step 113a of the cylinder 113 and the step 112a of the piston 112 are engaged, the sealing property between the outer peripheral wall of the piston 112 and the inner peripheral wall of the cylinder 113 is maintained.

  Further, the piston 112 is provided with a plurality (two in the case of FIG. 4) of oil supply ports 115 penetrating in the axial direction of the piston 112 in the circumferential direction. The oil filler port 115 penetrates in the axial direction of the piston 112 and opens on the lower surface of the stepped portion 112a.

A method of using such a bolt tensioner 100 will be described.
A casing bolt 103 is inserted into the flange portion 102 of the turbine casing. A nut 104 is screwed onto the casing bolt 103 and the nut 104 is rotated around the axis of the casing bolt 103 until the nut 104 is seated on the upper surface of the flange portion 102. A ram chair 110 is provided on the outer periphery of the nut 104 seated on the upper surface of the flange portion 102. A bolt tensioner main body 111 is provided at the upper end of the ram chair 110 so as to cover the outer periphery above the passenger compartment bolt 103.

  When the bolt tensioner main body 111 is provided on the outer periphery of the passenger compartment bolt 103, the screw portion provided on the outer peripheral wall of the passenger compartment bolt 103 is engaged with the screw portion provided on the inner peripheral wall of the piston 112. A screw engagement portion 105 is provided.

  In this way, oil is guided from the oil supply port 115 to the bolt tensioner main body 111 installed in the vehicle compartment bolt 103 to supply hydraulic pressure. The oil supplied to the oil filler 115 is guided from the axial direction of the piston 112 to the step portion 112a. Since the oil supply port 115 opens to the lower surface of the stepped portion 112a, the oil guided to the stepped portion 112a is between the upper surface of the stepped portion 113a of the cylinder 113 and the lower surface of the stepped portion 112a of the piston 112 (pressure receiving portion 117). To be derived.

  Due to the hydraulic pressure led out to the pressure receiving portion 117, a force (downward direction indicated by a white arrow in FIG. 4) acting in the direction of the flange portion 102 of the turbine casing acts on the step portion 113 a of the cylinder 113. A force (upward direction indicated by a solid arrow in FIG. 4) acting on the top side of the casing bolt 3 acts on the stepped portion 112a.

  Since an upward force acts on the piston 112 as indicated by a solid arrow, the casing bolt 103 engaged with the piston 112 in the screw engagement portion 105 is also indicated by a large white arrow in FIG. An upward tensile force (axial force) is generated. Thus, when the tensile force is generated in the upward direction, the vehicle compartment bolt 103 extends in the upward direction.

  With the casing bolt 103 extending upward, a nut rotation bar (not shown) is inserted into the nut tightening window 118 provided on the side wall of the ram chair 110 and screwed into the casing bolt 103. The mating nut 104 is rotated about the axial direction of the vehicle compartment bolt 103. The nut 104 is rotated until the nut 104 is seated on the upper surface of the flange portion 102 of the turbine casing.

  After the nut 104 is seated on the upper surface of the flange portion 102 of the turbine casing, the hydraulic pressure is released from the oil supply port 115 of the piston 112. When the hydraulic pressure is released, the force (upward direction indicated by a white arrow and downward direction indicated by a solid arrow) that has been applied to the pressure receiving portion 117 is released.

  When the upward force acting on the piston 112 is released, the tensile force generated in the passenger compartment bolt 103 engaged with the piston 112 via the screw engagement portion 105 is released. When the tensile force is released, the casing bolt 103 tries to return to the original state, but as the nut 104 is tightened, the casing bolt 103 remains stretched and the turbine casing is tightened.

Patent Documents 1 to 3 disclose a bolt tensioner having a plurality of pistons.
Patent Document 4 to Patent Document 6 disclose an invention of a nut tightening window provided on a side wall of a ram chair of a bolt tensioner.

Japanese Patent Laid-Open No. 11-300547 JP-A-9-1474 Japanese Patent Publication No. 3-25648 JP-A-62-73911 JP 2000-336616 A JP 2010-112422 A

  Here, when hydraulic pressure is supplied to the oil supply port 115 of the piston 112 of the bolt tensioner 100 shown in FIG. 4, a downward force is applied to the cylinder 113 and a compression stress is applied to the ram chair 110. However, as shown in FIG. 5, the ram chair 110 of the bolt tensioner 100 shown in FIG. 4 is provided with one nut tightening window 118 above the approximate center in the axial direction of the ram chair 110. Therefore, when compressive stress acts on the ram chair 110 and the nut tightening window 118 bends downward, the ram chair 110 is inclined to the side having the nut tightening window 118.

  Therefore, when the ram chair 110 is inclined to the side having the nut tightening window 118, the tensile force applied to the vehicle compartment bolt 103 (see FIG. 4) via the ram chair 110 is applied to the axial direction of the vehicle compartment bolt 103. There was a problem that it was impossible to make it act symmetrically.

  Further, the bending of the nut tightening window 118 causes a problem that stress concentrates on the top of the substantially elliptical nut tightening window 118 and a crack occurs.

  This invention is made | formed in view of such a situation, Comprising: It aims at providing the ram chair for fastening devices which can prevent the deformation | transformation which arises by oil_pressure | hydraulic, and a clamping device provided with the same.

In order to solve the above problems, the ram chair for a fastening device of the present invention and the fastening device including the same employ the following means.
That is, the fastening device ram chair according to the present invention is used in a fastening device that grips one end of a bolt and applies a tensile force in the axial direction to rotate and fasten a nut screwed to the bolt. A ram chair for a fastening device in which a compressive force is applied in the axial direction as a reaction force of the tensile force, and the nut is rotated around the axis of the bolt on a substantially cylindrical side wall provided on the outer periphery of the nut A plurality of holes for inserting the rotating means to be inserted are provided, and the plurality of holes are provided symmetrically with respect to the axis.

  The ram chair for a fastening device for fastening a nut to a bolt is provided with a plurality of holes for inserting a rotating means for rotating the nut around the axis of the bolt on the side wall, and the holes are symmetrical with respect to each other. It was decided to become. As a result, even when the hole provided in the side wall of the ram chair for the fastening device is deformed (flexed) due to a compressive force acting in the axial direction of the ram chair for the fastening device during fastening, the hole is provided at the symmetrical position. Since the portion is similarly deformed, the tensile force applied to the bolt via the fastening device ram chair is applied symmetrically with respect to the axis. Accordingly, a tensile force can be applied uniformly to the axis of the bolt, and the bolt can be efficiently tightened.

Furthermore, according to the ram chair for a fastening device according to the present invention, the plurality of hole portions are provided so as to intersect with surfaces having the same distance from both ends of the side wall, and the plurality of the central portions in the axial direction are provided with the plurality of the hole portions. A hole is provided.

  A plurality of holes are provided at a substantially central portion in the axial direction of the ram chair for fastening device, and the holes are positioned farthest from both ends of the ram chair for fastening device to ensure rigidity. Therefore, even when a compressive force is applied to the fastening device ram chair at the time of fastening, the hole portion can be prevented from being deformed (bent).

  Furthermore, according to the ram chair for a fastening device according to the present invention, each of the hole portions has a shape having a long axis in a circumferential direction of the nut, and a slit portion is provided at the end of the long shaft. To do.

  A hole having a major axis in the circumferential direction of the nut is provided with a slit at the end of the major axis. Therefore, it can reduce that the stress of the edge part of the long-axis end of a hole part concentrates. Therefore, the crack which generate | occur | produces in a hole part can be suppressed.

  Furthermore, according to the fastening device according to the present invention, the fastening device ram chair according to any one of the above is provided.

A ram chair for a fastening device capable of applying a tensile force uniformly to the bolt was used. Thereby, a volt | bolt can be extended uniformly. Therefore, the bolt and the nut can be tightened efficiently.
In addition, since the fastening device ram chair capable of suppressing the occurrence of cracks in the hole is used, the safety of the fastening operation of fastening the bolt and the nut using the fastening device can be improved.

  The ram chair for a fastening device for fastening a nut to a bolt is provided with a plurality of holes for inserting a rotating means for rotating the nut around the axis of the bolt on the side wall, and the holes are symmetrical with respect to each other. It was decided to become. As a result, even when the hole provided in the side wall of the ram chair for the fastening device is deformed (flexed) due to a compressive force acting in the axial direction of the ram chair for the fastening device during fastening, the hole is provided at the symmetrical position. Since the portion is similarly deformed, the tensile force applied to the bolt via the fastening device ram chair is applied symmetrically with respect to the axis. Accordingly, a tensile force can be applied uniformly to the axis of the bolt, and the bolt can be efficiently tightened.

It is a schematic block diagram of the bolt tensioner provided with the ram chair of this invention. It is a ram chair concerning one embodiment of the present invention, (A) is the perspective view, and (B) is a side view of (A). It is a figure which shows rotating the nut shown in FIG. 1 around the axis line of a volt | bolt. It is a schematic block diagram of the conventional bolt tensioner. 4A is a perspective view of the ram chair shown in FIG. 4, and FIG. 4B is a side view of FIG. 4A.

FIG. 1 shows a schematic configuration diagram of a bolt tensioner including a ram chair according to an embodiment of the present invention, FIG. 2 shows the ram chair shown in FIG. 1, and FIG. 1 shows a state in which the nut shown in FIG. 1 is rotated around the axis of the bolt.
A turbine casing (not shown) of a gas turbine (not shown) or a steam turbine (not shown) is vertically divided into two. A casing bolt (bolt) 3 is inserted through the flange portion 2 of the turbine casing thus divided. A nut 4 is screwed around the axis of the vehicle compartment bolt 3. The turbine casings divided into upper and lower parts are fastened together by rotating the nuts 4 screwed into the casing bolts 3 until they are seated on the upper surface of the flange part 2 of the turbine casing.

Such a vehicle compartment bolt 3 is fastened using a bolt tensioner 1 as shown in FIG.
The bolt tensioner (clamping device) 1 is for fastening by rotating a nut 4 screwed into the vehicle compartment bolt 3 while holding one end of the vehicle compartment bolt 3 and applying a tensile force in the axial direction. is there. A bolt tensioner 1 is a ram chair (ram chair for fastening device) provided on the outer surface of a casing bolt 3 inserted through a hole 2a provided in a flange portion 2 of a turbine casing and on an upper surface of the flange portion 2 of the turbine casing. ) 10 and a bolt tensioner main body 11 mounted on the upper end of the ram chair 10.

  The ram chair 10 has a substantially cylindrical shape, and a nut 4 penetrating the casing bolt 3 is accommodated in the inner periphery thereof. The lower end portion of the ram chair 10 is in contact with the upper surface of the flange portion 2 of the turbine casing. The upper end portion of the ram chair 10 is slightly longer in the axial direction than the upper end portion of the nut 4.

  The ram chair 10 has a plurality of nut tightening windows (holes) for inserting nut rotating bars (rotating means) 28 (see FIG. 3) for rotating the nut 4 about the axis of the vehicle compartment bolt 3 on the side wall thereof. Part) 18. As shown in FIG. 2A, the nut tightening window 18 provided in the ram chair 10 is provided at a substantially central portion in the axial direction of the ram chair 10, and is provided at, for example, four places (plural). . Of the nut tightening windows 18 provided at four places, two places (indicated by group A in FIG. 2A) are provided at positions close to each other, and the other two places (see FIG. A) is shown symmetrically with respect to the axis of the vehicle compartment bolt 3 (see FIG. 1), and is provided at a position 180 ° in the circumferential direction from the A group.

  As shown in FIG. 2B, each nut tightening window 18 has a substantially oval shape (shape) having a long axis in the circumferential direction of the nut 4 (see FIG. 1). A slit portion 19 is provided at the substantially elliptical long axis end of the nut tightening window 18. The slit 19 is open at a predetermined length in the circumferential direction of the nut 4 from the apex of the substantially elliptical long axis end of the nut tightening window 18, and the axial interval is, for example, approximately It is about 1 mm.

  The bolt tensioner body 11 is a double piston type in which pistons 12 and 22 and cylinders 13 and 23 are provided in two stages. The bolt tensioner body 11 is mounted on the upper end of the ram chair 10.

  The piston 22 constituting the bolt tensioner main body 11 has a substantially cylindrical shape. A casing bolt 3 is accommodated on the inner peripheral side of the substantially cylindrical piston 22.

  Further, on the outer peripheral wall of the piston 22, a step portion 22c is formed in the vicinity of the lower portion in the axial direction so as to protrude outward in the radial direction. An O-ring 30 is provided on the outer peripheral wall of the stepped portion 22c, and the hermeticity between the inner wall of a cylinder 23 described later is maintained. The lower end portion of the piston 22 is provided so as to be positioned above the nut 4.

  A screw portion (not shown) that can be engaged with a screw portion (not shown) provided on the outer peripheral wall of the casing bolt 3 is provided on the inner peripheral wall of the piston 22. A meshing portion 24 is formed. In addition, a screw portion (not shown) that can mesh with a screw portion (not shown) provided on the inner peripheral wall of the piston 12 described later is provided on the outer peripheral wall above the piston 22. The screw engagement part 25 is formed by meshing.

  A substantially cylindrical piston 12 is provided on the outer periphery above the piston 22. As described above, a screw portion that can be engaged with the screw portion provided on the outer peripheral wall of the piston 22 is provided above the inner peripheral wall of the substantially cylindrical piston 12. An O-ring 31 is provided on the inner peripheral wall below the piston 12 where the screw portion is provided, and the sealing performance between the piston 22 is maintained. An O-ring 32 is also provided on the outer peripheral wall of the piston 12 at a position substantially the same as the position where the O-ring 31 is provided. The O-ring 32 maintains a sealing property with a cylinder 13 described later.

  A substantially cylindrical cylinder 13 is provided on the outer periphery below the piston 12. A substantially cylindrical cylinder 14 sandwiched between the cylinder 13 and the piston 22 is provided on the inner peripheral wall of the substantially cylindrical cylinder 13. The cylinder 13 and the cylinder 14 are formed by meshing a screw portion (not shown) provided on the inner peripheral wall of the cylinder 13 and a screw portion (not shown) provided on the outer peripheral wall of the cylinder 14. Are connected by a screw engaging portion 26.

  An O-ring 33 is provided on the inner peripheral wall of the cylinder 14 to maintain the sealing performance with the piston 22 described above. Further, an O-ring 35 is provided on the outer peripheral wall of the cylinder 14 to maintain the sealing performance with the cylinder 13 described above. The upper surface of the cylinder 14 is mounted so that the lower end of the piston 12 is in contact therewith.

  A cylinder 23 is provided between the cylinder 13 and the ram chair 10. The cylinder 23 has a substantially cylindrical shape, and a step portion 23a that protrudes radially inward is provided at the lower end thereof. The step portion 23a can be engaged with the step portion 22c of the piston 22 described above. Further, an O-ring 34 is provided on the inner peripheral wall of the step portion 23a, and the sealing property between the piston 22 is maintained.

Next, the usage method of such a bolt tensioner 1 is demonstrated.
The casing bolt 3 is inserted into the hole 2a of the flange portion 2 of the turbine casing. The nut 4 screwed around the axis of the passenger compartment bolt 3 is rotated and seated on the upper surface of the flange portion 2. A ram chair 10 is provided on the outer periphery of the nut 4 seated on the upper surface of the flange portion 2. A bolt tensioner body 11 is provided on the outer periphery of the bolt 3 at the upper end of the ram chair 10.

  That is, the piston 22 is inserted from the upper end of the vehicle compartment bolt 3. At this time, the piston 22 is inserted so that the stepped portion 22c faces downward. The screw portion provided on the inner peripheral wall of the inserted piston 22 and the screw portion provided on the outer peripheral wall of the vehicle compartment bolt 3 are engaged with each other. Further, the cylinder 23 is provided so that the stepped portion 23 a of the cylinder 23 is sandwiched between the upper end of the ram chair 10 and the lower surface of the stepped portion 22 c provided on the outer peripheral wall of the piston 22.

  A cylinder 13 and a cylinder 14 coupled to each other are mounted on the upper end of the Linder 23 thus provided. At this time, the inner peripheral wall of the cylinder 14 is provided so as to abut against the outer peripheral wall of the piston 22, and a screw portion provided on the outer peripheral wall of the cylinder 14 and a screw portion provided on the inner peripheral wall of the cylinder 13 are provided. Engage. Thereafter, the lower end of the piston 12 is inserted between the inner periphery above the cylinder 13 and the outer periphery of the piston 22. At this time, the screw portion provided on the inner peripheral wall of the piston 12 and the screw portion provided on the outer peripheral wall of the piston 22 are engaged with each other, and the lower end of the piston 12 is brought into contact with the upper surface of the cylinder 14.

A tightening method using the bolt tensioner 1 thus provided will be described.
Oil pressure is supplied from the outside to the oil supply ports 13a and 23a that are open to the outer periphery of the cylinders 13 and 23 that constitute the bolt tensioner body 11. The oil supplied to the oil supply ports 13a and 23a is guided to the oil supply paths 13b and 23b extending radially inward from the outer peripheral walls of the cylinders 13 and 23, and the lower end of the piston 12 and the upper surface of the cylinder 14 (First stage pressure receiving part 17) and between the lower surface of the step part 22c provided on the outer peripheral wall of the piston 22 and the upper surface of the step part 23a of the cylinder 23 (second stage pressure receiving part 27). The

  Here, the O-rings 31, 32, 33, 35 are arranged between the inner peripheral wall of the piston 12 and the outer peripheral wall of the piston 22, between the outer peripheral wall of the piston 12 and the inner peripheral wall of the cylinder 13, and The space between the inner peripheral wall of the cylinder 14 and the space between the inner peripheral wall of the cylinder 13 and the outer peripheral wall of the cylinder 14 are sealed. Therefore, due to the hydraulic pressure of the oil led out to the first-stage pressure receiving portion 17, a force (downward direction indicated by a white arrow in FIG. 1) acting on the cylinder 14 toward the flange portion 2 of the turbine casing acts. At the lower end of the piston 12, a force (upward direction indicated by a solid arrow in FIG. 1) acting in the direction opposite to the flange portion 2 of the turbine casing acts.

  The upward force acting on the piston 12 is transmitted to the piston 22 via the screw engagement portion 25. Further, the upward force acting on the piston 22 is transmitted to the vehicle compartment bolt 3 via the screw engagement portion 24. As a result, an upward tensile force (axial force) is generated in the vehicle compartment bolt 3 as indicated by the large white arrow in FIG. 1, and the vehicle compartment bolt 3 extends upward.

  Further, the O-rings 30 and 34 provide a clearance between the outer peripheral wall of the stepped portion 22c of the piston 22 and the inner peripheral wall of the cylinder 23, and between the outer peripheral wall of the lower portion of the piston 22 and the inner peripheral wall of the stepped portion 23a of the cylinder 23. Each is sealed. For this reason, the oil pressure led to the second-stage pressure receiving portion 27 causes the stepped portion 23a of the cylinder 23 to exert a force toward the flange portion 2 of the turbine casing (downward direction indicated by a white arrow in FIG. 1). ) Acts on the stepped portion 22c of the piston 22 and acts in a direction opposite to the flange portion 2 of the turbine casing (upward direction indicated by a solid arrow in FIG. 1).

The upward force acting on the piston 22 is transmitted to the vehicle compartment bolt 3 via the screw engagement portion 24. Thereby, in addition to the axial force due to the hydraulic pressure acting on the first-stage pressure receiving portion 17 described above, an axial force is further generated in the passenger compartment bolt 3 in the upward direction.
Due to the hydraulic pressure acting on the first-stage pressure receiving portion 17 and the second-stage pressure receiving portion 27 as described above, the casing bolt 3 extends upward, whereby the nut 4 is lifted from the upper surface of the flange portion 2 of the turbine casing.

  In order to seat the nut 4 floating from the upper surface of the flange portion 2 of the turbine casing, a nut rotating bar 28 is inserted into a nut tightening window 18 provided on the side wall of the ram chair 10 as shown in FIG. Then, the tip end portion of the nut rotation bar 28 is inserted into the nut rotation hole 4 a provided on the side surface of the nut 4.

  The nut rotation bar 28 inserted through the nut rotation hole 4a is moved in the long axis direction of the nut tightening window 18 (circumferential direction of the nut 4). As a result, the nut 4 rotates around the axis of the vehicle compartment bolt 3 (see FIG. 1). When the nut rotating bar 28 reaches the long axis end of the nut tightening window 18, the nut rotating bar 28 is pulled out from the nut rotating hole 4 a and the nut tightening window 18. Next, the nut rotation bar 28 is inserted into another nut tightening window 18 which is provided symmetrically with respect to the axis with respect to the nut tightening window 18 into which the nut rotation bar 28 has been inserted, Similarly, the nut 4 is rotated around the axis of the vehicle compartment bolt 3. By repeating these steps, the nut 4 is rotated around the axis of the vehicle compartment bolt 3 using the nut rotating bar 28 until the nut 4 is seated on the upper surface of the flange portion 2 of the turbine casing.

  When the nut 4 is seated on the upper surface of the flange portion 2 of the turbine casing, the hydraulic pressure supplied to the bolt tensioner body 11 is released. When the hydraulic pressure is released, the force (upward direction indicated by a white arrow and downward direction indicated by a solid arrow) acting on the first-stage pressure receiving part 17 and the second-stage pressure receiving part 27 is released.

  Therefore, the axial force generated in the casing bolt 3 engaged through the screw engaging portion 25 and the screw engaging portion 24 is released. When the axial force is released, the vehicle compartment bolt 3 tries to return to the original state. However, as the nut 4 is tightened, the vehicle compartment bolt 3 remains stretched and the fastening is completed.

As described above, the ram chair 10 according to the present embodiment and the bolt tensioner 1 including the ram chair 10 have the following operational effects.
The ram chair (fastening device ram chair) 10 of the bolt tensioner (fastening device) 1 for fastening the passenger compartment nut (nut) 4 to the bolt 3 is for rotating the nut by rotating the nut 4 around the axial line of the passenger compartment bolt 3 on its side wall. A plurality of (for example, four) nut tightening windows (holes) 18 for inserting the bars (rotating means) 28 are provided so that the nut tightening windows 18 are symmetrical with respect to each other. It was decided. As a result, even when the nut tightening window 18 provided on the side wall of the ram chair 10 is deformed (flexed) due to a compressive force acting in the axial direction of the ram chair 10 at the time of fastening, it is in a symmetrical position. Since the nut tightening window 18 is similarly deformed, the tensile force applied to the vehicle compartment bolt 3 via the ram chair 10 is applied symmetrically with respect to the axis. Therefore, it is possible to apply a tensile force uniformly to the axis of the vehicle compartment bolt 3 and to tighten efficiently.

  Four nut tightening windows 18 are provided in the substantially central portion of the ram chair 10 in the axial direction, and the nut tightening windows 18 are positioned farthest from both ends of the ram chair 10 to ensure rigidity. Therefore, even when a compressive force is applied to the ram chair 10 at the time of fastening, it is possible to prevent the nut fastening window 18 from being deformed (bent).

  The substantially oval (shaped) nut tightening window 18 having a long axis in the circumferential direction of the nut 4 is provided with a slit portion 19 at the end of the long axis. Therefore, it is possible to reduce the concentration of stress at the top (end) of the long axis end of the nut tightening window 18. Therefore, cracks generated in the nut tightening window 18 can be suppressed.

The ram chair 10 capable of applying a tensile force uniformly to the passenger compartment bolt 3 was used. Thereby, the vehicle compartment bolt 3 can be extended uniformly. Therefore, the vehicle compartment bolt 3 and the nut 4 can be efficiently tightened.
Further, since the ram chair 10 capable of suppressing the occurrence of cracks occurring in the nut tightening window 18 is used, the safety of the fastening operation for fastening the vehicle compartment bolt 3 and the nut 4 using the bolt tensioner 1 is enhanced. Can be improved.

1 Tightening device (bolt tensioner)
3 bolts (vehicle compartment bolts)
4 Nut 10 Lamb chair for fastening device (ram chair)
18 hole (nut tightening window)
19 Slit 28 Rotating means (nut rotating bar)

Claims (3)

Used in a fastening device that grips one end of a bolt and applies a tensile force in the axial direction to rotate and fasten a nut screwed to the bolt, and compresses the axial force as a reaction force of the tensile force. A ram chair for fastening devices to which
A plurality of hole portions for inserting rotation means for rotating the nut around the axis of the bolt are provided on a substantially cylindrical side wall provided on the outer periphery of the nut,
The plurality of hole portions are provided so as to intersect with surfaces having the same distance from both ends of the side wall, and are provided symmetrically with respect to the axis. Each said hole has a shape having a major axis in the circumferential direction of the nut, Ramuchea fastening device according to claim 1, characterized in that the slit portion is provided on its major axis end. A fastening device comprising the ram chair for a fastening device according to claim 1 .

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