JP2014114942A - Fastening structure of bolt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fastening structure of a bolt capable of reducing stress applied to a bolt fastened to a casing of a turbine even when the casing is thermally expanded.SOLUTION: A fastening structure 1 of a bolt 10 inserted into a bolt hole 14 of a casing of a turbine to be fastened and having a head 21 includes a first tapered part 22 provided between the head 21 of the bolt 10 and an upper horizontal flange 5a and having a first tapered surface P3 tapered toward the casing side in an axial direction of the bolt 10, and a washer 11 as a second tapered part provided between the first tapered part 22 and the upper horizontal flange 5a and having a second tapered surface P4 abutted to the first tapered surface P3 and expanded toward the first tapered part 22 side in the axial direction. The washer 11 is expanded to the outer side in a radial direction of the bolt 10 when the first tapered surface P3 is pressed onto the second tapered surface P4.

Description

  The present invention relates to a fastening structure for bolts fastened to a turbine casing.

  Conventionally, the end of the bolt hole provided in the horizontal flange of the turbine casing is dished, and a washer made of a material having a low coefficient of thermal expansion having a conical surface matching the dished surface of this end is inserted, and the bolt is inserted into the bolt hole. A structure that is inserted and fastened to a nut is known (for example, see Patent Document 1).

Japanese Utility Model Publication No. 60-87303

  By the way, the turbine casing to which the bolts are fastened is heated by a heat medium (for example, steam or combustion gas) flowing inside when the operation is started. Thereby, the heated turbine casing is thermally expanded. Here, the bolt fastened to the turbine casing has a small area in contact with the turbine casing. For this reason, since it becomes difficult to heat a volt | bolt, the temperature rise of a volt | bolt is delayed compared with the temperature rise of a turbine casing. Accordingly, since the temperature difference between the turbine casing and the bolt is widened, the bolt is thermally expanded after the turbine casing is thermally expanded.

  When the turbine casing is thermally expanded before the bolt is thermally expanded, the bolt fastened to the turbine casing is pulled in the axial direction as the turbine casing is thermally expanded. For this reason, stress is applied to the bolt in the axial direction.

  Accordingly, an object of the present invention is to provide a bolt fastening structure capable of reducing the stress applied to the bolt fastened to the casing even if the casing of the turbine is thermally expanded.

  The bolt fastening structure according to the present invention is a bolt fastening structure having a head that is inserted into a bolt hole formed in a turbine casing and fastened, and is provided between the bolt head and the casing. A first taper portion having a first taper surface that tapers toward the vehicle interior side in the axial direction of the bolt, and is provided between the first taper portion and the vehicle interior, and is in contact with the first taper surface. And a second tapered portion having a second tapered surface that widens toward the first tapered portion in the axial direction.

  According to this configuration, when the passenger compartment is thermally expanded before the thermal expansion of the bolt, the space between the head of the bolt and the passenger compartment is narrowed. Then, the second taper portion on the passenger compartment side is pressed against the first taper portion on the bolt side, so that the second taper surface is pressed against the first taper surface, and the second taper portion is on the outer side in the radial direction of the bolt. spread. Then, when the second taper portion spreads outward in the radial direction of the bolt, the length of the first taper portion and the second taper portion in the axial direction, that is, the head portion of the bolt, corresponding to the spread of the second taper portion The length between the passenger compartment is shortened. For this reason, the thermal expansion of the passenger compartment can be absorbed by the first tapered portion and the second tapered portion, and the stress applied to the bolt can be reduced. The bolt may be a bolt with an integrated head, or a bolt with a separate head (for example, a stud bolt).

  In this case, it is preferable that the 1st taper part is united with the volt | bolt, and the 2nd taper part is a washer provided between the 1st taper part of a volt | bolt, and a vehicle interior.

  According to this configuration, since the first tapered portion can be integrated with the bolt and the second tapered portion can be used as a washer, a simple configuration using the bolt and the washer can be achieved.

  In this case, it is preferable that the first taper portion and the second taper portion serve as a washer having a divided structure provided between the first taper portion of the bolt and the passenger compartment.

  According to this configuration, it is not necessary to process the bolt, and an existing bolt can be used.

  In this case, it is preferable that the 2nd taper part is formed in the cyclic | annular form continued in the circumferential direction of a volt | bolt.

  According to this configuration, since the second taper portion can be a single body, the second taper portion can be easily handled.

  In this case, it is preferable that an annular outer peripheral member provided along the outer periphery of the second taper portion is further provided, and the second taper portion is divided into a plurality of portions in the circumferential direction of the bolt.

  According to this configuration, since the spread of the second taper portion can be regulated by the outer peripheral member, the spread of the second taper portion can be adjusted by appropriately changing the shape and thickness of the outer peripheral member. Can do.

  In this case, the bolt hole is a through hole, and the bolt preferably further includes a nut having a head portion on one side in the axial direction and fastened to the other side in the axial direction of the bolt.

  According to this structure, even if it is a case where a bolt hole is a through-hole, a 1st taper part and a 2nd taper part can be arrange | positioned, and a bolt can be fastened to a vehicle interior.

FIG. 1 is a cross-sectional view schematically illustrating a bolt fastening structure according to the first embodiment. FIG. 2 is a plan view of the washer according to the first embodiment. FIG. 3 is an explanatory diagram regarding thermal expansion of the bolt fastening structure according to the first embodiment. FIG. 4 is a cross-sectional view schematically illustrating a bolt fastening structure according to the second embodiment. FIG. 5 is a plan view of the washer according to the second embodiment. FIG. 6 is a cross-sectional view schematically showing a bolt fastening structure according to the third embodiment. FIG. 7 is a cross-sectional view schematically illustrating a bolt fastening structure according to the fourth embodiment.

  Embodiments according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same.

  FIG. 1 is a cross-sectional view schematically illustrating a bolt fastening structure according to the first embodiment. FIG. 2 is a plan view of the washer according to the first embodiment. As shown in FIG. 1, the fastening structure 1 of the bolt 10 according to the first embodiment is a fastening structure including a bolt 10 and a washer 11. The bolt 10 is fastened to the turbine casing. First, a turbine casing to which the bolt 10 is fastened will be briefly described.

  Although not shown in the drawings, the turbine casing is a split casing, and is divided into an upper casing and a lower casing, for example, with the casing mating surface P1 (see FIG. 1) as a boundary. Yes. As shown in FIG. 1, the upper casing is provided with an upper horizontal flange 5a that contacts the lower casing, and the lower casing is provided with a lower horizontal flange 5b that contacts the upper horizontal flange 5a.

  A bolt hole 14 through which the bolt 10 is inserted is formed through the upper horizontal flange 5a. The bolt hole 14 has a cylindrical inner peripheral surface. The lower horizontal flange 5b is formed with a fastening hole 15 to which the tip of the bolt 10 is fastened. The fastening hole 15 has the same diameter as the bolt hole 14 and has a thread groove formed on the inner peripheral surface. That is, the fastening hole 15 is a female screw. The upper horizontal flange 5a and the lower horizontal flange 5b are mated at the vehicle interior mating surface P1 so that the bolt hole 14 and the fastening hole 15 overlap.

  In addition, as a turbine, there are a steam turbine in which steam as a heat medium flows, or a gas turbine in which combustion gas as a heat medium flows, and the fastening structure 1 of the bolt 10 is applied to any turbine. Also good.

  The fastening structure 1 of the bolt 10 fastens the upper horizontal flange 5a and the lower horizontal flange 5b that are mated on the passenger compartment mating surface P1. The fastening structure 1 of the bolt 10 includes a bolt 10 that is inserted into the bolt hole 14 and fastened to the fastening hole 15, and a washer 11 that is disposed between the seat surface of the bolt 10 and the upper horizontal flange 5 a. .

  The bolt 10 has a head portion 21, a first taper portion 22, and a shaft portion 23, and is formed integrally. The head 21 is formed larger than the bolt hole 14. The first taper portion 22 is provided between the head portion 21 and the shaft portion 23. The first taper portion 22 has a first taper surface P3 that tapers from the head 21 side (upper side) toward the shaft portion 23 side (lower side) in the axial direction of the bolt 10. That is, the first tapered surface P3 is formed such that the diameter on the head 21 side is larger than the diameter on the shaft portion 23 side. For this reason, the diameter of the first tapered surface P3 in contact with the head portion 21 is the same as the diameter of the head portion 21, and the diameter of the first tapered surface P3 in contact with the shaft portion 23 is the same as the diameter of the shaft portion 23. It has the same diameter. The first taper surface P3 functions as a seating surface of the bolt 10. As for the axial part 23, the thread groove is formed in the outer peripheral surface. That is, the shaft portion 23 is a male screw. At this time, the thread groove of the shaft portion 23 may be formed only in a portion to be fastened with the fastening hole 15 or may be formed over the entire length of the shaft portion 23. And the fastening force with respect to the fastening hole 15 of this volt | bolt 10 is a predetermined fastening force prescribed | regulated previously.

  As shown in FIGS. 1 and 2, the washer 11 has an annular shape in which the shape of the bolt 10 viewed from the axial direction is continuous in the circumferential direction, and the insertion hole 25 through which the bolt 10 is inserted penetrates the center. Is formed. The washer 11 is made of the same material as the bolt 10 and uses, for example, a metal such as steel. The washer 11 has a second tapered surface P4 that contacts the first tapered surface P3 of the bolt 10 and a contact surface P5 that contacts the upper surface P6 of the upper horizontal flange 5a. That is, the washer 11 functions as a second tapered portion having the second tapered surface P4.

  The second tapered surface P4 is formed to have a complementary shape to the first tapered surface P3, and in the axial direction of the bolt 10, from the shaft portion 23 side (lower side) of the bolt 10 to the head 21 side (upper side). It has a tapered surface that spreads out toward. That is, the second tapered surface P4 is formed such that the upper diameter is larger than the lower diameter. The contact surface P5 is a surface orthogonal to the axial direction of the bolt 10. The washer 11 is formed so that the second taper surface P4 and the contact surface P5 are provided at a predetermined interval in the axial direction of the bolt 10.

  Note that the washer 11 has a second tapered surface P4 and a contact surface P5, and the second taper surface P4 and the contact surface P5 are provided at a predetermined interval in the axial direction of the bolt 10. The cross section cut by a plane orthogonal to the circumferential direction may be any cross sectional shape.

  When the bolt 10 is fastened to the fastening hole 15 with a predetermined fastening force, the washer 11 does not spread outward in the radial direction, but when a pressing force larger than the predetermined fastening force is applied, It is formed in a shape and thickness that spreads outward. Further, even when the washer 11 spreads outward in the radial direction, the washer 11 is elastically deformed so as to be restored to the original shape, that is, contracted inward in the radial direction.

  Here, the frictional force between the first taper surface (seat surface) P3 of the bolt 10 and the second taper surface P4 of the washer 11 is between the contact surface P5 of the washer 11 and the upper surface P6 of the upper horizontal flange 5a. The frictional force may be increased.

  On the other hand, the frictional force between the first tapered surface (seat surface) P3 of the bolt 10 and the second tapered surface P4 of the washer 11 is between the contact surface P5 of the washer 11 and the upper surface P6 of the upper horizontal flange 5a. It may be smaller than the frictional force.

  At this time, the frictional force between the first taper surface (seat surface) P3 of the bolt 10 and the second taper surface P4 of the washer 11 is the surface roughness of the first taper surface P3 and the surface roughness of the second taper surface P4. Of these, it is preferable to change the surface roughness of at least one to a predetermined frictional force. Similarly, the frictional force between the contact surface P5 of the washer 11 and the upper surface P6 of the upper horizontal flange 5a is at least one of the surface roughness of the contact surface P5 and the surface roughness of the upper surface P6. It is preferable to change to a predetermined frictional force. Thus, the frictional force between the first taper surface (seat surface) P3 of the bolt 10 and the second taper surface P4 of the washer 11, the contact surface P5 of the washer 11 and the upper surface P6 of the upper horizontal flange 5a. It is possible to appropriately adjust (control) the frictional force between them by changing the surface roughness, and a predetermined frictional force suitable for expansion and contraction in the radial direction of the washer 11 can be obtained.

  Next, a fastening method for fastening the bolt 10 to the turbine casing and assembling the fastening structure 1 of the bolt 10 will be described. First, the upper horizontal flange 5a and the lower horizontal flange 5b are mated at the vehicle interior mating surface P1 so that the bolt hole 14 and the fastening hole 15 overlap. Subsequently, the upper surface P6 of the upper horizontal flange 5a and the contact surface P5 of the washer 11 are mated so that the bolt hole 14 and the insertion hole 25 overlap. Then, the bolt 10 is inserted in the order of the insertion hole 25 and the bolt hole 14, and then the tip of the bolt 10 is fastened to the fastening hole 15 with a predetermined fastening force. As a result, the bolt 10 is fastened to the fastening hole 15 so that the upper surface P6 of the upper horizontal flange 5a and the contact surface P5 of the washer 11 are in contact with each other, and the second tapered surface P4 of the washer 11 and the first of the bolt 10 are contacted. The upper horizontal flange 5a and the lower horizontal flange 5b are connected with the tapered surface P3 in contact.

  Next, the transition of thermal expansion related to the fastening structure 1 of the bolt 10 will be described with reference to FIG. FIG. 3 is an explanatory diagram regarding thermal expansion of the bolt fastening structure according to the first embodiment. The diagram on the left side of FIG. 3 is a diagram before the start of operation of the turbine, the diagram at the center of FIG. 3 is a diagram immediately after the operation of the turbine, and the diagram on the right side of FIG. It is.

  As shown in the diagram on the left side of FIG. 3, the vehicle compartment is not heated before the start of operation of the turbine. For this reason, the upper horizontal flange 5a and the lower horizontal flange 5b are not thermally expanded, and the bolt 10 is not thermally expanded.

  When the operation of the turbine is started from this state, the vehicle compartment is heated by circulating the heat medium inside the vehicle compartment. As shown in the center diagram of FIG. 3, when the passenger compartment is heated, the upper horizontal flange 5a and the lower horizontal flange 5b are thermally expanded. That is, in the axial direction of the bolt 10, the upper horizontal flange 5a and the lower horizontal flange 5b are thicker. On the other hand, since the heat input to the bolt 10 is small immediately after the start of operation of the turbine, the bolt 10 has no thermal expansion or a small thermal expansion. That is, the bolt 10 has an axial length that is substantially the same as the axial length shown in the left figure. For this reason, the space between the upper surface P6 of the upper horizontal flange 5a and the first tapered surface P3 of the bolt 10 becomes narrower. When the space between the upper surface P6 and the first tapered surface P3 becomes narrow, the washer 11 is pressed against the bolt 10. For this reason, the washer 11 spreads outward in the radial direction of the bolt 10 by the second tapered surface P4 of the washer 11 being pressed against the first tapered surface P3. When the washer 11 spreads outward in the radial direction of the bolt 10, the length between the first tapered surface P3 of the bolt 10 and the upper surface P6 of the upper horizontal flange 5a can be shortened by the amount of spread of the washer 11.

  From this state, when the turbine is in rated operation and the passenger compartment and the bolt 10 are sufficiently heated, the bolt 10 is thermally expanded as shown in the diagram on the right side of FIG. When the bolt 10 is thermally expanded, the shaft portion 23 of the bolt 10 becomes longer in the axial direction. At this time, the passenger compartment maintains a state of thermal expansion. For this reason, the space between the upper surface P6 of the upper horizontal flange 5a and the first tapered surface P3 of the bolt 10 becomes wider. When the space between the upper surface P6 and the first tapered surface P3 becomes wider, the pressing force from the bolts 10 on the washer 11 decreases. For this reason, the washer 11 contracts radially inward against the pressing force from the bolt 10. When the washer 11 is contracted inward in the radial direction of the bolt 10, the space between the first tapered surface P <b> 3 of the bolt 10 and the upper surface P <b> 6 of the upper horizontal flange 5 a can be filled as the washer 11 contracts.

  As described above, according to the configuration of the first embodiment, the upper horizontal flange 5a and the lower horizontal flange 5b are thermally expanded, and the seating surface (first tapered surface P3) of the bolt 10 and the upper surface P6 of the upper horizontal flange 5a. When the space is narrowed, the washer 11 spreads outward in the radial direction of the bolt 10. And the length between the 1st taper surface P3 of the volt | bolt 10 and the upper surface P6 of the top horizontal flange 5a can be shortened because the washer 11 spreads to the outer side of radial direction, and the tension | tensile_strength of the volt | bolt 10 is absorbed. be able to. Thereby, since the stress given to the volt | bolt 10 can be reduced, the service life of the volt | bolt 10 can be lengthened.

  Moreover, according to the structure of Example 1, the volt | bolt 10 has the 1st taper part 22 united, and the washer 11 can function as a 2nd taper part. For this reason, the fastening structure 1 of the bolt 10 can be made into a simple structure using the bolt 10 and the washer 11.

  Moreover, according to the structure of Example 1, since the washer 11 can be formed in the cyclic | annular form continuous in the circumferential direction, the washer 11 can be easily handled alone.

  In the first embodiment, the bolt 10 is a bolt in which the head 21 is integrated, but is not limited to this configuration. For example, a stud bolt with a separate head may be applied.

  Next, with reference to FIG.4 and FIG.5, the fastening structure 30 of the volt | bolt 10 which concerns on Example 2 is demonstrated. In the second embodiment, only parts different from the first embodiment will be described in order to avoid duplicated descriptions with the first embodiment. FIG. 4 is a cross-sectional view schematically illustrating a bolt fastening structure according to the second embodiment. FIG. 5 is a plan view of the washer according to the second embodiment. In the first embodiment, the washer 11 is formed in an annular shape that is continuous in the circumferential direction. In the second embodiment, the washer 31 is divided into a plurality of pieces in the circumferential direction. Hereinafter, the fastening structure 30 of the bolt 10 will be described.

  As shown in FIG. 4, the fastening structure 30 of the bolt 10 according to the second embodiment includes the bolt 10, a washer 31, and an outer peripheral member 32. The upper horizontal flange 5a, the lower horizontal flange 5b, and the bolt 10 have the same configuration as that of the first embodiment, and thus the description thereof is omitted.

  As shown in FIGS. 4 and 5, the washer 31 has a structure in which the washer 11 of the first embodiment is divided into a plurality of parts along the circumferential direction of the bolt 10. Specifically, the washer 31 has a plurality of divided washers 31a cut in a cross shape around the insertion hole 25 of the washer 11 of the first embodiment, and each divided washer 31a is formed in a fan shape.

  The outer peripheral member 32 is provided in an annular shape along the outer peripheral surface of the divided washer 31 and restricts the washer 31 that spreads outward in the radial direction of the bolt 10. The outer peripheral member 32 is made of the same material as the washer 31 and uses, for example, a metal such as a steel material.

  When the bolt 10 is fastened to the fastening hole 15 with a predetermined fastening force, the outer peripheral member 32 is provided with a pressing force larger than the predetermined fastening force while the washer 31 does not spread outward in the radial direction. The shape and the thickness are formed so as to spread outward in the radial direction. Further, even when the outer peripheral member 32 spreads outward in the radial direction, the outer peripheral member 32 is elastically deformed so as to be restored to the original shape, that is, contracted inward in the radial direction.

  As described above, according to the configuration of the second embodiment, since the spread of the washer 31 can be regulated by the outer circumferential member 32, the washer 31 can be appropriately changed by changing the shape, thickness, and the like of the outer circumferential member 32. You can adjust the spread.

  Next, with reference to FIG. 6, the fastening structure 40 of the volt | bolt 10 which concerns on Example 3 is demonstrated. In the third embodiment, only parts different from the first embodiment will be described in order to avoid duplicated descriptions with the first embodiment. FIG. 6 is a cross-sectional view schematically showing a bolt fastening structure according to the third embodiment. In the first embodiment, the bolt 10 is fastened to the fastening hole 15 in the lower horizontal flange 5 b, but in the third embodiment, the bolt 10 is fastened to the nut 43. Hereinafter, the fastening structure 40 of the bolt 10 will be described.

  As shown in FIG. 6, the fastening structure 40 of the bolt 10 according to the third embodiment includes the bolt 10, the washer 11, the nut 43, and the washer 44. In addition, since the volt | bolt 10 and the washer 11 are the structures similar to Example 1, description is abbreviate | omitted.

  An upper bolt hole 41 through which the bolt 10 is inserted is formed through the upper horizontal flange 5a. The upper bolt hole 41 has the same configuration as the bolt hole 14 of the first embodiment. The lower horizontal flange 5b is formed with a lower bolt hole 42 through which the bolt 10 is inserted. The lower bolt hole 42 has a cylindrical inner peripheral surface and has the same diameter as the upper bolt hole 41. The upper horizontal flange 5a and the lower horizontal flange 5b are mated at the vehicle interior mating surface P1 so that the upper bolt hole 41 and the lower bolt hole 42 overlap.

  The bolt 10 is inserted through the upper bolt hole 41 and the lower bolt hole 42 in this order. The shaft portion 23 of the bolt 10 is formed such that the tip portion protrudes from the lower bolt hole 42. The nut 43 is formed larger than the lower bolt hole 42, and a fastening hole 45 through which the tip of the shaft portion 23 of the bolt 10 is fastened is formed at the center thereof. The fastening hole 45 has a thread groove formed on the inner peripheral surface. That is, the nut 43 is a female screw.

  The washer 44 is disposed between the seat surface of the nut 43 and the lower horizontal flange 5b. The shape of the washer 44 viewed from the axial direction of the bolt 10 is an annular thin plate that is continuous in the circumferential direction, and an insertion hole 46 through which the bolt 10 is inserted is formed through the center. The washer 44 is made of the same material as the bolt 10 and uses, for example, a metal such as a steel material.

  As described above, according to the configuration of the third embodiment, when the bolt hole of the passenger compartment is a through hole, that is, the upper horizontal flange 5a and the lower horizontal flange 5b are penetrated by the upper bolt hole 41 and the lower bolt hole 42. Even if it is formed, the vehicle compartment can be fastened by using the bolt 10 and the nut 43.

  Next, with reference to FIG. 7, the fastening structure 50 of the volt | bolt 51 which concerns on Example 4 is demonstrated. In the fourth embodiment, only parts different from the first embodiment will be described in order to avoid duplicated descriptions with the first embodiment. FIG. 7 is a cross-sectional view schematically illustrating a bolt fastening structure according to the fourth embodiment. In the first embodiment, the first tapered portion 22 is provided integrally with the bolt 10 and the second tapered portion is used as the washer 11. However, in the fourth embodiment, the washer 52 is provided with the first tapered portion and the second tapered portion. ing. Hereinafter, the fastening structure 50 of the bolt 51 will be described. Since the upper horizontal flange 5a and the lower horizontal flange 5b have the same configuration as that of the first embodiment, the description thereof is omitted.

  As shown in FIG. 7, the fastening structure 50 of the bolt 51 according to the fourth embodiment includes a bolt 51 and a washer 52. The bolt 51 has a head portion 61 and a shaft portion 62 and is integrally formed. The head 61 is formed larger than the bolt hole 14, and the surface (lower surface) on the shaft portion 62 side is a seating surface P7. The seat surface P <b> 7 is a surface orthogonal to the axial direction of the bolt 51. The shaft portion 62 is a male screw having a thread groove formed on the outer peripheral surface.

  The washer 52 is divided in the axial direction of the bolt 51, and includes an upper washer 52a and a lower washer 52b. The upper washer 52a functions as a first tapered portion having a first tapered surface P3, and the lower washer 52b functions as a second tapered portion having a second tapered surface P4.

  The shape of the upper washer 52a viewed from the axial direction of the bolt 51 is an annular shape that is continuous in the circumferential direction, and an insertion hole 64 through which the bolt 51 is inserted is formed through the center. The upper washer 52a is made of the same material as the bolt 51, and uses, for example, a metal such as a steel material. The upper washer 52a has an upper surface P8 that contacts the seating surface P7 of the bolt 51, and a first tapered surface P3 that contacts the lower washer 52b. The upper surface P8 of the upper washer 52a is a surface parallel to the upper surface P6 of the upper horizontal flange. The first tapered surface P3 is configured in the same manner as in the first embodiment, and is tapered from the head 61 side (upper side) to the shaft part 62 side (lower side) in the axial direction of the bolt 51. .

  The shape of the lower washer 52b viewed from the axial direction of the bolt 51 is an annular shape that is continuous in the circumferential direction, and an insertion hole 65 through which the bolt 51 is inserted is formed through the center. The lower washer 52b is also made of the same material as the bolt 51, and uses, for example, a metal such as a steel material. The lower washer 52b has a second tapered surface P4 that contacts the first tapered surface P3 of the upper washer 52a, and an abutting surface P5 that contacts the upper surface P6 of the upper horizontal flange 5a. The 2nd taper surface P4 is comprised similarly to Example 1, and is a taper surface which spreads from the axial part 62 side (downward side) of the volt | bolt 51 toward the head 61 side (upper side). The contact surface P5 is also configured in the same manner as in the first embodiment, and is a surface orthogonal to the axial direction of the bolt 51.

  In the washer 52, the upper washer 52a and the lower washer 52b are formed in a shape and thickness so that when the bolt 51 is fastened to the fastening hole 15 with a predetermined fastening force, it does not spread outward in the radial direction. On the other hand, when a pressing force larger than a predetermined fastening force is applied, the upper washer 52a does not spread outward in the radial direction, while the lower washer 52b has a shape and thickness that spreads outward in the radial direction. Formed. Further, even when the lower washer 52b spreads outward in the radial direction, the lower washer 52b is elastically deformed so as to be restored to the original shape, that is, contracted inward in the radial direction.

  As described above, according to the configuration of the fourth embodiment, it is not necessary to process the bolt 51, and the existing bolt 51 can be used.

  In addition, you may combine the structure described in Example 1 to 4 suitably. For example, the configuration of the second embodiment may be combined with the configuration of the third embodiment, or the configuration of the second embodiment may be combined with the configuration of the fourth embodiment.

DESCRIPTION OF SYMBOLS 1 Bolt fastening structure 5a Upper horizontal flange 5b Lower horizontal flange 10 Bolt 11 Washer 14 Bolt hole 15 Fastening hole 21 Head 22 First taper part 23 Shaft part 25 Insertion hole 30 Bolt fastening structure (Example 2)
31 Washer (Example 2)
32 Peripheral member 40 Bolt fastening structure (Example 3)
41 Upper Bolt Hole 42 Lower Bolt Hole 43 Nut 44 Washer (Example 3)
45 Fastening hole 46 Insertion hole 50 Bolt fastening structure (Example 4)
51 bolts (Example 4)
52 Washer 52a Upper Washer 52b Lower Washer 61 Head 62 Shaft 64 Upper Washer Insertion Hole 65 Lower Washer Insertion Hole P1 Car Seat Matching Surface P3 First Tapered Surface P4 Second Tapered Surface P5 Washer Contact Surface P6 Upper Horizontal Flange top surface P7 Bolt seat surface P8 Top washer top surface

Claims (6)

A bolt fastening structure having a head inserted into a bolt hole formed in a turbine casing and fastened,
A first tapered portion provided between the head portion of the bolt and the casing, and having a first tapered surface that tapers toward the casing side in the axial direction of the bolt;
A second taper portion provided between the first taper portion and the passenger compartment, having a second taper surface that abuts the first taper surface and extends toward the first taper portion in the axial direction; And a bolt fastening structure. The first tapered portion is integrated with the bolt,
2. The bolt fastening structure according to claim 1, wherein the second taper portion is a washer provided between the first taper portion of the bolt and the casing.   The said 1st taper part and the said 2nd taper part are the washers of the division structure provided between the said 1st taper part of the said volt | bolt, and the said vehicle interior. Bolt fastening structure.   4. The bolt fastening structure according to claim 1, wherein the second tapered portion is formed in an annular shape that is continuous in a circumferential direction of the bolt. 5. An annular outer peripheral member provided along the outer periphery of the second tapered portion;
4. The bolt fastening structure according to claim 1, wherein the second tapered portion is divided into a plurality of parts in a circumferential direction of the bolt. 5. The bolt hole is a through hole,
The bolt has a head on one side in the axial direction,
The bolt fastening structure according to any one of claims 1 to 5, further comprising a nut fastened to the other side in the axial direction of the bolt.

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