JP2012159169A - Fastening structure and washer unit used in the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fastening structure reducing a torque necessary for fastening a nut by arranging a thrust rolling bearing between the nut and a member to be fastened reducing the cost of the fastening structure by making it possible to use a general-purpose nut as the nut.SOLUTION: A washer unit 18 comprising a washer body 23 and a lock ring 24 is constituted separately from the nut 16. The washer body 23 is arranged between the nut 16 and the thrust rolling bearing 17 arranged on the surface of an upper case 13 and screwed and connected to a male screw 23a arranged in an outer periphery of the washer body 23, thereby the lock ring 24 is mounted on the outer periphery of the washer body 23. The seat surface 24c of the lock ring 24 is brought into pressed contact with the surface of the upper case 13 after fastening the nut 16, thereby to prevent the loosening of the nut 16.

Description

  The present invention relates to a fastening structure in which a thrust rolling bearing is disposed between a seat surface of a nut and a surface of a member to be fastened to reduce a torque necessary for tightening the nut, and a washer unit used therefor. .

  In a fastening structure in which a fastened member is fastened using a bolt and a nut, a nut that is screwed to the tip of the bolt is rotated in a fastening direction with a predetermined torque to generate a fastening axial force on the bolt. Usually, a washer formed by a metal plate is disposed between the nut and the member to be fastened, and the nut is structured to be tightened while causing sliding friction against the washer (see Patent Document 1). .

  However, in a structure where the nut causes sliding friction against the washer during tightening, 50% or more of the tightening torque applied to the nut is consumed by the frictional resistance between the nut and the washer, which is effective for generating actual bolt axial force. It does not contribute. Therefore, a large torque is required for tightening the nut.

  Therefore, a thrust rolling bearing is arranged between the nut and the fastened member and rolling friction is generated between the nut and the fastened member so that the frictional resistance is smaller than that in the case of sliding friction. A rolling friction type fastening structure that reduces the torque required for fastening has been developed.

  Here, the rotational torque T (Nm) of the nut in the fastening structure using the bolt and the nut is the screw diameter of the bolt D (mm), the screw pitch of the bolt p (mm), and the screw thread angle α (Degrees), when the average bearing surface diameter of the nut is Dz (mm), the friction coefficient of the thread surface is μ, the friction coefficient of the seating surface of the fastened member is μz, and the generated axial force of the bolt is F (kN), the bolt Is a metric screw with α = 60 degrees, the effective screw diameter of the bolt Da (mm) = D−0.6495 × p and the average bearing surface diameter Dz = 1.32 × D. As a result, the friction angle ρ = atan (μ / cos (π / 6) and the friction angle γ = atan (p / (π × Da)) corresponding to the thread angle, and the rotational torque necessary for tightening the nut The relational expression between T and the generated axial force F of the bolt is T = F × (0.5 × (Da × tan ρ + γ) + Dz × μz)) become. Here, the screw surface frictional corresponding torque component = Da × tan (ρ + γ), the seat surface frictional corresponding torque component is = Dz × μz.

  When sliding friction occurs between the nut and the member to be fastened, the screw diameter D of the bolt (M36) D = 36 (mm), the pitch p = 4.0 (mm), μ = 0.12, and μz = 0.14. When an axial force of 435 kN is generated on the bolt by the standard nut, Da = 33.402 (mm), Dz = 47.52 (mm), ρ = 0.138, γ = 0.038, and T = 435 × 0.5 × (33.402 × tan (0.138 + 0.038) + 47.52 × 0.14) = 2737 Nm.

  On the other hand, when a thrust rolling bearing (inner diameter 40φ, outer diameter 90φ, static permissible load 435kN) is arranged between the nut and the member to be fastened, and rolling friction is caused between the nut and the member to be fastened. Similarly, when an axial force of 435 kN is generated on a bolt by a standard nut having a screw diameter D = 36 (mm) and a pitch p = 4.0 (mm) of the bolt (M36), an average bearing surface diameter Dz = (40 + 90) × 0.5 = 65 (mm), and the friction coefficient μz between the nut and the member to be fastened by the thrust rolling bearing is an estimated value of μz = 0.014, which is 1/10 of the sliding friction. , T = 435 × 0.5 × (33.402 × tan (0.138 + 0.038) + 65 × 0.014) = 1488 Nm.

  As can be seen from the above comparison, in the structure where the friction between the nut and the member to be fastened is a rolling friction using a thrust rolling bearing, the generation ratio of the bolt axial force to the tightening torque applied to the nut is improved, and the bolt is The tightening torque of the nut necessary for generating the necessary axial force can be reduced to about 40 to 50% when sliding friction is formed between the nut and the fastened member.

  On the other hand, the frictional resistance generated between the nut and the member to be fastened also acts as a resistance force to prevent the nut from loosening after tightening, so a thrust rolling bearing is simply arranged between the nut and the member to be fastened. Then, it becomes easy to loosen a nut. Therefore, in a fastening structure in which a thrust rolling bearing is provided between a nut and a member to be fastened, how to provide a structure for preventing the nut from loosening becomes an important issue.

  As such a loosening prevention structure, for example, gear teeth are integrally formed on the outer periphery of the thrust rolling bearing, and a fastening member such as a screw is used on the outer peripheral portion of the nut after tightening the metal fitting engaged with the gear teeth. It is known that the nut is prevented from rotating in the loosening direction by being fixed.

JP 2006-242206 A

  However, in the conventional loosening prevention structure using gear teeth and metal fittings, the nut is not a general-purpose product such as a JIS standard standard product but a specially processed product with a screw hole for fixing the metal fitting. It is necessary to use it. Therefore, there has been a problem that the cost of the nut becomes very high.

  An object of the present invention is to enable a general-purpose product to be used as a nut in a fastening structure in which a thrust rolling bearing is disposed between the nut and a member to be fastened to reduce torque required for tightening the nut. This is to reduce the cost of this fastening structure.

  The fastening structure of the present invention is a fastening structure for fastening a member to be fastened by a bolt and a nut, comprising a thrust rolling bearing disposed between the nut and the member to be fastened, a male screw on the outer periphery, and the nut And a washer body disposed between the thrust rolling bearing and a lock ring that is formed in a cylindrical shape and is screwed to the male screw in a female screw provided on the inner periphery thereof, and is attached to the washer body. After the nut is tightened to the tightened state, the lock ring is rotated and pressed against the member to be fastened to prevent the nut from rotating in the loosening direction. It is characterized by having.

  The fastening structure of the present invention is characterized in that the seating surface of the lock ring that contacts the member to be fastened is subjected to processing for increasing the surface roughness.

  The fastening structure of the present invention is characterized in that the pitch of the male screw is set larger than the pitch of the nut.

  In the fastening structure of the present invention, a holding portion that protrudes radially inward is provided on the inner periphery of the lock ring, and the thrust rolling bearing is held between the holding portion and the washer body to hold the thrust rolling bearing. It is constructed integrally with the washer unit.

  The washer unit of the present invention is a washer unit used in a fastening structure in which a thrust rolling bearing is disposed between a nut to be screwed to a bolt and a member to be fastened, and has a male screw on the outer periphery, and the nut and the thrust rolling A washer body disposed between the bearing and a lock ring that is formed in a cylindrical shape and is coupled to the male screw in a female screw provided on an inner periphery thereof, and is attached to the washer body; After being tightened to the tightened state, the lock ring is rotated and pressed against the member to be fastened to prevent the nut from rotating in the loosening direction.

  The washer unit of the present invention is characterized in that the seating surface of the lock ring that contacts the fastened member is processed to increase the surface roughness.

  The washer unit of the present invention is characterized in that the pitch of the male screw is set larger than the pitch of the nut.

  The washer unit of the present invention includes a holding portion that protrudes radially inward on the inner periphery of the lock ring, and holds the thrust rolling bearing between the holding portion and the washer body, and is integrated with the thrust rolling bearing. It is characterized by being configured.

  According to the present invention, the washer unit provided with a lock ring for preventing loosening of the nut after tightening is configured separately from the nut, and the washer unit is disposed between the nut and the thrust rolling bearing. Therefore, general-purpose products such as JIS standard products can be used as nuts. As a result, it is not necessary to use a dedicated nut for providing a locking function, and the cost of this fastening structure can be reduced. Further, when the thrust rolling bearing is configured separately from the washer unit, a general-purpose product such as a standard product of JIS standard can be used as the thrust rolling bearing, and the cost of this fastening structure can be further reduced. .

  According to the present invention, since the seat surface contacting the fastened member of the lock ring is subjected to processing for increasing the surface roughness, the effect of preventing the nut from loosening can be further enhanced.

  According to the present invention, since the pitch of the male screw is set larger than the pitch of the nut, when the nut tries to rotate in the loosening direction due to vibration or the like, the loosening direction of the nut caused by the rotation in the loosening direction The movement allowance in the tightening direction of the lock ring caused by the rotation of the washer body together with the nut is larger than the movement allowance to the lock ring, and the lock ring is prevented from rotating in the loosening direction of the nut due to vibration or the like. Thereby, loosening of a nut can be prevented reliably.

  According to the present invention, the thrust rolling bearing is held between the holding portion provided on the inner periphery of the lock ring and the washer body so that the thrust rolling bearing is configured integrally with the washer unit. The rolling bearing can be attached to the bolt as one unit. Therefore, the fastening operation using this fastening structure can be facilitated.

It is sectional drawing which shows the case where the fastening structure which is one embodiment of this invention is applied to the assembly of a turbine case. It is a disassembled perspective view of the fastening structure shown in FIG. It is sectional drawing which shows the state before the lock ring fastening of the fastening structure shown in FIG. It is sectional drawing which shows the state after the lock ring fastening of the fastening structure shown in FIG. FIG. 4 is a cross-sectional view showing a modification of the fastening structure shown in FIG. 3, in which a thrust rolling bearing is configured integrally with a washer unit.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a case where a fastening structure 11 according to an embodiment of the present invention is applied to an assembly of a turbine case 12 used in a power plant such as a power plant. The turbine case 12 houses therein a turbine (not shown) that converts thermal energy such as high-temperature and high-pressure gas or steam into mechanical energy, and includes an upper case (fastened member) 13 and a lower case (fastened) Member) 14 in combination. Each case 13 and 14 is provided with flanges 13a and 14a, and these flanges 13a and 14a are fastened to each other by a fastening structure 11.

  The fastening structure 11 of the present invention is basically a thrust rolling bearing between the seat surface 16a of the nut 16 and the surface of the flange 13a of the upper case 13, which is a member to be fastened, based on the fastening using the bolt 15 and the nut 16. 17 is arranged to reduce the torque required for tightening the nut 16 and to prevent loosening of the nut 16 after fastening over a long period of time using the washer unit 18 according to an embodiment of the present invention. It is what.

  The flanges 13a and 14a of the cases 13 and 14 are provided with through holes 13b and 14b so that the axial centers thereof coincide when the flanges 13a and 14a are combined. The shaft 15a of the bolt 15 is inserted into the through holes 13b and 14b from the side of the lower case 14, and the tip of the bolt 15 protrudes from the surface of the flange 13a of the upper case 13. A nut 16 is screwed to the shaft portion 15a protruding from the upper case of the bolt 15, and an axial force is generated in the bolt 15 by tightening the nut 16 with a predetermined torque. As a result, the flanges 13a and 14a are sandwiched between the head portion 15b of the bolt 15 and the seating surface 16a of the nut 16 in a state where the bolt axial force is applied, and both the cases 13 and 14 are fastened.

  As these bolts 15 and nuts 16, general-purpose products such as standard bolts and standard nuts described in JIS standards can be used. Further, as the bolt 15 and the nut 16, those having a size capable of generating the bolt axial force necessary for fastening the turbine case 12 are selected.

  As described above, the thrust rolling bearing 17 is disposed between the seat surface 16a of the nut 16 and the surface of the flange 13a of the upper case 13 that is a member to be fastened. The thrust rolling bearing 17 includes a large number of rolling elements 17b held at predetermined intervals in the circumferential direction by a cage 17a. The thrust rolling bearing 17 is formed in an annular shape having an inner diameter larger than the outer diameter of the shaft portion 15 a of the bolt 15, and is attached to the shaft portion 15 a of the bolt 15 at the shaft center. The thrust rolling bearing 17 attached to the bolt is disposed coaxially with the bolt 15 between the nut 16 and the upper case 13.

  In the illustrated case, the thrust rolling bearing 17 is a roller thrust bearing in which a roller (roller) is used as the rolling element 17b. By disposing the thrust rolling bearing 17, rolling friction is formed between the seating surface 16 a of the nut 16 and the surface of the upper case 13. As a result, the frictional resistance between the seating surface 16a of the nut 16 and the surface of the upper case 13 becomes smaller than that in the case of sliding friction, and the nut 16 can be tightened by a corresponding amount of torque.

  As the thrust rolling bearing 17, a general-purpose product such as a standard product described in the JIS standard can be used. For the thrust rolling bearing 17, the basic static load rating, bearing inner diameter, bearing outer diameter, and bearing thickness are appropriate by referring to the bearing manufacturer's specification table etc. according to the size of the bolt 15 and the required axial force. Is selected.

  In the present embodiment, a roller thrust bearing in which the rolling element 17b is a roller is used as the thrust rolling bearing 17. However, the present invention is not limited to this, and a ball thrust bearing or rolling element in which the rolling element 17b is a ball (ball). Other types such as a needle thrust bearing in which 17b is a needle (needle roller) may be used.

  A lower washer 21 is disposed between the thrust rolling bearing 17 and the upper case 13. The lower washer 21 is formed in a flat ring shape from a metal material such as a steel material, and is attached to the shaft portion 15a of the bolt 15 at its axis. The lower washer 21 attached to the bolt 15 is arranged on the surface of the upper case 13 so as to be coaxial with the bolt 15. An upper washer 22 is disposed between the thrust rolling bearing 17 and the nut 16. The upper washer 22 is also formed in a flat ring shape from a metal material such as steel, and is attached to the shaft portion 15a of the bolt 15 at the axis. The upper washer 22 attached to the bolt 15 is arranged on the thrust rolling bearing 17 so as to be coaxial with the bolt 15. These washer washers 21 and 22 also function as bearing rings of the thrust rolling bearing 17, and the respective rolling elements 17 b roll on the surfaces of the lower washer 21 and the upper washer 22. . Thus, the thrust rolling bearing 17 has a configuration in which the rolling elements 17b held by the cage 17a are sandwiched between the lower washer 21 and the upper washer 22.

  Next, the configuration of the washer unit 18 of the present invention will be described.

  The washer unit 18 includes a washer body 23 and a lock ring 24 attached to the outer periphery of the washer body 23.

  The washer body 23 is formed in a disk shape from a metal material such as a steel material, and a male screw 23a is integrally provided on the outer periphery of the washer body 23 over the entire axial direction. Further, a through hole 23b having a diameter larger than the outer diameter of the shaft portion 15a of the bolt 15 is provided in the shaft center of the washer body 23, and the washer body 23 is attached to the shaft portion 15a of the bolt 15 in the through hole 23b. Has been. The washer body 23 attached to the bolt 15 is disposed between the upper washer 22 (thrust rolling bearing 17) and the nut 16 so as to be coaxial with the bolt 15. One end surface of the washer body 23 in the axial direction is in contact with the seat surface 16 a of the nut 16, and the other end surface is in contact with the upper washer 22.

  The lock ring 24 is formed in a cylindrical shape from a metal material such as steel, and an internal thread 24a is provided on the inner periphery thereof. The female screw 24a has a screw diameter corresponding to the male screw 23a of the washer body 23, and the pitch thereof is the same as that of the male screw 23a. The axial dimension of the portion of the lock ring 24 where the female screw 24 a is provided is larger than the axial dimension of the washer body 23. A load receiving portion 24b having an inner diameter smaller than that of the portion where the female screw 24a is provided is integrally provided at one end of the lock ring 24 in the axial direction. The load receiving portion 24 b is formed so that its inner diameter is smaller than the outer diameter of the washer body 23 and larger than the outer diameter of the thrust rolling bearing 17. Moreover, the end surface which faces the axial direction of the load receiving part 24b is a seating surface 24c perpendicular to the axial direction.

  The lock ring 24 is mounted on the outer periphery of the washer main body 23 by screwing the female screw 24 a to the male screw 23 a of the washer main body 23. When the lock ring 24 is attached to the washer body 23, the thrust rolling bearing 17 is accommodated inside the lock ring 24.

  A plurality of rotation holes 24 d are provided on the outer peripheral surface of the lock ring 24. These turning holes 24d are for engaging a tool (not shown) such as a pin wrench. The lock ring 24 can be rotated by a tool engaged with these turning holes 24d. By rotating the lock ring 24 with respect to the washer body 23 using a tool, the lock ring 24 can be moved in the axial direction (vertical direction) with respect to the washer body 23. The range of movement of the lock ring 24 relative to the washer body 23 is such that the nut 16 is tightened between the seat surface 24 c and the upper case 13 before the nut 16 is tightened to the bolt 15. A sufficient gap that is equal to or greater than the compression amount of each of the washer washers 21 and 22 and the thrust rolling bearing 17 can be generated. On the other hand, after the nut 16 is tightened to the bolt 15 to the tightened state, its seat surface 24c. Is set in such a range that can be pressed against the surface of the flange 13 a of the upper case 13.

  In the illustrated case, a plurality of turning holes 24d are provided on the outer peripheral surface of the cylindrical lock ring 24, and a tool such as a pin wrench is engaged with these turning holes 24d to tighten the lock ring 24. Not limited to this, the outer shape of the lock ring 24 is formed in a polygonal shape such as a hexagonal shape, and the lock ring 24 is rotated (tightened) with a tool such as a spanner wrench or an adjustable wrench engaged with the width of the two surfaces. Also good.

  Next, a procedure for fastening the upper case 13 and the lower case 14 with the fastening structure 11 will be described.

  The shaft portion 15a of the bolt 15 is inserted into the through holes 13b, 14b of the cases 13, 14 from the lower case 14 side, and the lower washer 21 is inserted from the tip of the shaft portion 15a of the bolt 15 protruding to the upper case 13 side. The lower washer 21 is mounted on the upper surface of the flange 13 a of the upper case 13.

  Next, the thrust rolling bearing 17 is mounted on the shaft portion 15 a of the bolt 15, and the thrust rolling bearing 17 is disposed on the lower washer 21. Further, an upper washer 22 is mounted on the shaft portion 15 a of the bolt 15, and this is disposed on the thrust rolling bearing 17.

  Next, the washer unit 18 is mounted by inserting the tip end of the shaft portion 15a of the bolt 15 into the through hole 23b of the washer body 23, and the washer body 23 is disposed on the upper washer washer 22. The lower surface is brought into close contact with the upper surface of the upper washer 22. At this time, there is a sufficient gap between the seating surface 24c of the lock ring 24 of the assembled washer unit 18 and the surface of the flange 13a of the upper case 13 (the washer body 23, the washer washers 21, 22 and a clearance larger than the compression amount of the thrust rolling bearing 17).

  After the washer unit 18 is assembled, the fastening nut 16 is screwed to the tip of the shaft portion 15 a of the bolt 15 and screwed until the seat surface 16 a comes into contact with the upper surface of the washer body 23. Thereby, the fastening structure 11 will be in the state before fastening shown in FIG.

  Next, torque is applied to the nut 16 screwed to the most distal side of the shaft portion 15a of the bolt 15 with a torque generating tool (not shown) such as a torque wrench (hydraulic torque wrench, booster wrench, air wrench) and tightened. . When a tightening torque is applied to the nut 16, the washer unit 18 that contacts the seating surface 16 a of the nut 16 also rotates together with the nut 16. At this time, since the thrust rolling bearing 17 is disposed between the washer body 23 (nut 16) and the upper case 13, rolling friction occurs between the nut 16, the washer unit 18 and the upper case 13. Therefore, the nut 16 can be tightened with a torque value that is 45% of the specified torque when the friction between the nut 16 and the upper case 13 is sliding friction.

  Next, a tool such as a pin wrench is engaged with a rotation hole 24d on the outer periphery of the lock ring 24 of the washer unit 18 while the nut 16 is held in a tightened state with a specified torque, and the lock ring 24 is fixed using this tool. Rotate. Then, the seating surface 24c of the lock ring 24 is seated on the surface of the flange 13a of the upper case 13, and the seating surface 24c is pressed against the surface of the flange 13a of the upper case 13 by further tightening.

  When the seating surface 24c of the lock ring 24 comes into pressure contact with the surface of the flange 13a of the upper case 13, the frictional resistance between the seating surface 16a of the nut 16 and the washer body 23, and the screw connection between the washer body 23 and the lock ring 24 Due to the frictional resistance of the portion and the frictional resistance between the seating surface 24c of the lock ring 24 and the surface of the flange 13a of the upper case 13, rotation of the nut 16 in the loosening direction is prevented, and loosening of the nut 16 is prevented.

  As described above, in the fastening structure 11 of the present invention, the thrust rolling bearing 17 is disposed between the nut 16 and the upper case 13 to reduce the torque necessary for tightening the nut 16 and after the nut 16 is tightened. Since the seat surface 24c of the lock ring 24 provided in the washer unit 18 is brought into pressure contact with the surface of the flange 13a of the upper case 13, the nut 16 is prevented from rotating in the loosening direction. Even if the thrust rolling bearing 17 is arranged between the nut 16 and the torque required for tightening the nut 16 is reduced, the nut 16 after fastening is prevented from rotating in the loosening direction. Looseness can be prevented.

  Further, in the fastening structure 11 of the present invention, the washer unit 18 for preventing loosening of the nut 16 after tightening is configured separately from the nut 16, and the washer unit 18 is formed between the nut 16 and the thrust rolling bearing 17. Since the nut 16 is prevented from loosening by being disposed between, a general-purpose product such as a JIS standard standard product can be used as the nut 16. That is, the fastening structure 11 can be provided with a function for preventing the nut 16 from loosening by using the washer unit 18 without using a dedicated nut for giving a function of preventing the loosening. Thereby, it is not necessary to use a dedicated nut, that is, it is possible to use a general-purpose nut 16, and the cost of the fastening structure 11 can be reduced.

  Furthermore, in the fastening structure 11 of the present invention, since the thrust rolling bearing 17 is also formed separately from the washer unit 18, a general-purpose product such as a JIS standard standard product can be used as the thrust rolling bearing 17. Thereby, the cost of this fastening structure 11 can further be reduced.

  Furthermore, in the fastening structure 11 of the present invention, after the nut 16 is tightened, a part of the axial force of the bolt 15 is also supported by the lock ring 24. Therefore, the axial force of the bolt 15 applied to the thrust rolling bearing 17 after the nut 16 is tightened is reduced accordingly. As a result, the rolling element 17b of the thrust rolling bearing 17 is prevented from buckling due to the axial force of the bolt 15, and the bolt axial force is reduced due to the buckling of the rolling element 17b and the nut 16 is loosened. Can be prevented. Even when the rolling element 17b of the thrust rolling bearing 17 is buckled without being able to withstand the axial force of the bolt 15, the axial force of the bolt 15 is mechanically supported by the lock ring 24. Even if 17b buckles, the nut 16 can be reliably prevented from loosening. That is, since a part of the axial force of the bolt 15 can be supported by the lock ring 24 after the nut 16 is tightened, the rolling element 17b of the thrust rolling bearing 17 is prevented from buckling and the rolling element 17b is buckled. Even so, the axial force of the bolt 15 can be supported by the lock ring 24 and the loosening of the nut 16 can be prevented for a long time.

  In order to increase the locking effect of the nut 16 by the lock ring 24, it is effective to increase the frictional resistance between the seating surface 24c of the lock ring 24 and the surface of the upper case 13. Therefore, in the present fastening structure 11, the surface roughness of the seating surface 24c of the lock ring 24, that is, the surface roughness is formed to be rough during machining, and the friction coefficient generated between the seating surface 24c and the upper case 13 is increased. Like to do. As a process for increasing the surface roughness of the seating surface 24c, for example, there is a shot peening process for the seating surface 24c of the lock ring 24. In this case, the seating surface 24c is preferably a processed surface of 12S or more.

  As described above, in the fastening structure 11 of the present invention, the frictional resistance between the seating surface 24c of the lock ring 24 and the upper case 13 is increased by processing the seating surface 24c of the lock ring 24 to increase the surface roughness. Since it did in this way, the locking effect of the nut 16 using the lock ring 24 can further be improved.

  Further, in order to increase the locking effect of the nut 16 by the lock ring 24, the screw pitch of the male screw 23a of the washer body 23 and the female screw 24a of the lock ring 24 is made larger than the screw pitch of the bolt 15 and nut 16. Setting is also effective. If the screw pitch of the male screw 23a of the washer body 23 and the female screw 24a of the lock ring 24 is made larger than the screw pitch of the bolt 15 or nut 16, even if the nut 16 tries to rotate in the loosening direction due to vibration or the like, the rotation in the loosening direction will occur. The movement allowance in the tightening direction of the lock ring 24 caused by the rotation of the washer body 23 together with the nut 16 is larger than the movement allowance in the loosening direction of the nut 16 caused by the above. Therefore, rotation of the nut 16 in the loosening direction is prevented by the lock ring 24.

  In this way, in the fastening structure 11 of the present invention, the screw pitch of the male screw 23a of the washer body 23 and the female screw 24a of the lock ring 24 is set larger than the screw pitch of the bolt 15 and nut 16, so that vibration or the like The lock ring 24 prevents the nut 16 from rotating in the loosening direction, and the nut 16 can be reliably prevented from loosening.

  In the fastening structure 11 of the present invention, the position of the lock ring 24 before tightening (the state in which the lock ring 24 and the nut 16 are lightly hand-tightened) and the lock after tightening (after the lock ring 24 is pressed into contact with the upper case 13). The axial force of the bolt 15 can be managed by the amount of movement in the substantial axial direction before and after tightening of the lock ring 24 obtained from the position of the ring 24.

  Therefore, when a member to be fastened is fastened by a fastening structure 11 of the present invention at a number of points using a large number of bolts 15 and nuts 16, a substantial axial direction before and after the lock ring 24 is tightened is used. The amount of movement is measured for each fastening structure 11, and each bolt 15 is tightened by performing the fastening work of each fastening structure 11 so as to equalize the axial strain value of each bolt 15 obtained from these measurement results. Can be managed so that their axial forces are uniform with each other.

  FIG. 5 is a cross-sectional view showing a modification of the fastening structure shown in FIG. 3, in which the thrust rolling bearing 17 is configured integrally with the washer unit 18. In FIG. 5, members corresponding to those described above are denoted by the same reference numerals.

  In the case shown in FIG. 3, the washer unit 18 is configured separately from the nut 16 and the thrust rolling bearing 17. Therefore, when performing the fastening operation, the thrust rolling bearing 17 is attached to the shaft portion 15 a of the bolt 15. It is necessary to attach the washer unit 18 and the nut 16 separately in order.

  On the other hand, in the structure of the modified example shown in FIG. 5, the thrust rolling bearing 17 is incorporated in the washer unit 18 so as to be integrated with the washer unit 18, so that the washer unit 18 and the thrust rolling bearing 17 are provided. It can be attached to the shaft portion 15a of the bolt 15 as one unit.

  In this case, in order to hold the thrust rolling bearing 17, a holding portion 24 e is provided on the inner periphery of the load receiving portion 24 b of the lock ring 24. The holding portion 24e is formed integrally with the lock ring 24 and protrudes radially inward from the inner periphery of the lock ring 24. Even if the holding portion 24e has a disk-like configuration over the entire inner circumference of the lock ring 24, a plurality of holding portions 24e formed in a protruding shape have a predetermined interval in the circumferential direction on the inner circumference of the lock ring 24. It may be configured to be arranged.

  On the other hand, a held portion 21 a that can be engaged with the holding portion 24 e is integrally provided on the outer periphery of the lower washer 21 of the thrust rolling bearing 17. The held portion 21a is provided at a distance from the surface of the upper case 13, and a holding portion 24e is disposed between the held portion 21a and the surface of the upper case 13. Yes.

  A recess 23 c having the same diameter as the upper washer 22 is formed on the lower surface in contact with the upper washer 22 of the washer body 23. In the thrust rolling bearing 17, the held portion 21 a is engaged with the holding portion 24 e of the lock ring 24, and the upper washer 22 is engaged with the concave portion 23 c of the washer body 23, so that both washer washers 21 and 22 are engaged. At the same time, it is sandwiched between the holding portion 24 e and the washer body 23 and is held by the washer unit 18. When the upper washer 22 is engaged with the recess 23 c, the thrust rolling bearing 17 is positioned with respect to the washer body 23 so as to be coaxial with the bolt 15.

  To attach the thrust rolling bearing 17 to the washer unit 18, the lock ring 24 is removed from the washer unit 18, and in this state, the upper washer 22, the thrust rolling bearing 17, and the lower washer 21 are arranged in this order. Next, the lock ring 24 is mounted on the washer body 23 from below.

  Thus, in the fastening structure 11 of the present invention, the thrust rolling bearing 17 is held between the holding portion 24e provided on the inner periphery of the lock ring 24 and the washer body 23 so that the thrust rolling bearing 17 is integrated with the washer unit 18. Therefore, the washer unit 18 and the thrust rolling bearing 17 can be attached to the bolt 15 as one unit. Thereby, the man-hour of the fastening operation | work using this fastening structure 11 can be reduced, and the operation | work can be made easy.

  Further, by simply mounting the washer unit 18 and the thrust rolling bearing 17 integrally mounted on the shaft portion 15a of the bolt 15 and performing the tightening operation of the nut 16, the fastening structure with a normal bolt and nut can be easily achieved. Furthermore, the fastening structure 11 of the present invention in which the tightening force of the nut 16 is reduced using the thrust rolling bearing 17 can be obtained.

  It goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention.

  For example, in the said embodiment, although the fastening structure 11 of this invention is applied to the assembly of the turbine case 12, it is not restricted to this, The fastening structure 11 of this invention is used as a fastening structure which fastens another to-be-fastened member. May be used.

  In the embodiment, the upper washer 22 is formed separately from the washer body 23. However, the present invention is not limited to this, and the upper washer 22 is formed integrally with the washer body 23. Also good.

11 Fastening structure 12 Turbine case 13 Upper case (fastened member)
13a Flange 13b Through hole 14 Lower case (member to be fastened)
14a Flange 14b Through-hole 15 Bolt 15a Shaft 15b Head 16 Nut 16a Seating surface 17 Thrust rolling bearing 17a Cage 17b Rolling body 18 Washer unit 21 Lower washer washer 21a Holding part 22 Upper washer 23 Washer body 23a Male screw 23b Through Hole 23c Recess 24 Lock ring 24a Female screw 24b Load receiving portion 24c Seat surface 24d Rotating hole 24e Holding portion

Claims (8)

A fastening structure for fastening a fastening member with a bolt and a nut,
A thrust rolling bearing disposed between the nut and the fastened member;
A male washer on the outer periphery, and a washer body disposed between the nut and the thrust rolling bearing, and a cylindrically formed female screw provided on the inner periphery, and screwed to the male screw and attached to the washer body A washer unit with a lock ring to be
After the nut is tightened to the tightened state, the lock ring is rotated and pressed against the member to be fastened to prevent the nut from rotating in the loosening direction. Construction.   The fastening structure according to claim 1, wherein the seating surface of the lock ring in contact with the member to be fastened is processed to increase surface roughness.   3. The fastening structure according to claim 1, wherein a pitch of the male screw is set larger than a pitch of the nut.   The fastening structure according to any one of claims 1 to 3, wherein a holding portion that protrudes radially inward is provided on an inner periphery of the lock ring, and the thrust rolling bearing is provided between the holding portion and the washer body. The fastening structure is characterized in that the thrust rolling bearing is configured integrally with the washer unit. A washer unit used in a fastening structure in which a thrust rolling bearing is disposed between a nut and a member to be fastened to a bolt,
A washer body provided with an external thread on the outer periphery, and disposed between the nut and the thrust rolling bearing;
A lock ring which is formed in a cylindrical shape and is attached to the washer body by screw coupling to the male screw in a female screw provided on the inner periphery;
A washer unit that prevents the nut from rotating in the loosening direction by rotating the lock ring and press-contacting the member to be fastened after the nut has been tightened.   The washer unit according to claim 5, wherein a process for increasing surface roughness is performed on a seating surface of the lock ring that contacts the fastened member.   The washer unit according to claim 5 or 6, wherein a pitch of the male screw is set larger than a pitch of the nut.   The washer unit according to any one of claims 5 to 7, further comprising a holding portion protruding radially inward on an inner periphery of the lock ring, wherein the thrust rolling bearing is provided between the holding portion and the washer body. And a washer unit configured integrally with the thrust rolling bearing.

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