JP2020020370A - Pulling device - Google Patents

Abstract

To have a pulling device screwed to a portion different from the shank of a bolt and pulling the bolt, thereby reducing an error in axial force detection, etc.SOLUTION: Provided is a pulling device 1 for pulling upward a bolt 10, with a washer 11 inserted through, that is fastened to an object H to be fastened, characterized by comprising: a connection member 2 having a first female thread part 21a1 to which a first male thread part 11a is screwed, the first male thread part 11a being formed on the outer circumferential surface of the washer 11; a pulling mechanism 3 for pulling the connection member 2 while the first male thread part 11a is screwed to the first female thread part 21a1; and a tension receiving part 4 arranged around the outer circumference of the connection member 2, for receiving a reaction force acting from the object H to be fastened when pulled by the pulling mechanism 3.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a tension device that pulls a bolt fastened to a body to be fastened upward.

  BACKGROUND ART Assembling of machines such as automobiles and structures such as bridges is performed using screws. The strength of the screw as a fastening member largely depends on the tightening force. On the other hand, the management of the fastening force in the bolted body is generally performed only at the time of tightening by measuring the torque and the rotation angle, and is hardly performed after the tightening. However, if the bolt is loosened due to unexpected external force during the operation of the machine and the tightening force is reduced, the risk of fatigue failure is significantly increased. Therefore, in order to prevent a bolt breakage accident and to improve the reliability of the screw fastener, it is necessary to pay attention to the detection of the bolt tightening force after fastening.

  Patent Literature 1 discloses a bolt / nut fastening body that narrows pressure on a body to be fastened by inserting a bolt into an insertion hole of the body to be fastened and screwing a nut into a male thread portion of the bolt that has passed through the insertion hole. Then, the male thread portion of the bolt protruding from the upper surface is pulled against the upper surface of the nut, a transition point of the spring constant of the bolt is detected, and the tensile force at the transition point is used as a tightening force. A method for detecting a tightening force of a bolt / nut fastener is disclosed.

Japanese Patent No. 4028254

  In the tightening force detecting method disclosed in Patent Document 1, it is necessary to screw a female screw portion of a tension member into a male screw portion of a bolt protruding from an upper surface of a nut. However, since the shaft diameter of the bolt is small and the length of the bolt shaft protruding from the upper surface of the nut is short, the circumferential length of the screw to be screwed may be insufficient. If the length of the screw to be screwed in the circumferential direction is insufficient, when the bolt is pulled via the tension member, the screw thread may be plastically deformed, and an error in axial force detection may increase.

  Accordingly, an object of the present invention is to reduce an error such as axial force detection by screwing a tension device to a portion different from the shaft portion of the bolt and pulling the bolt.

  In order to solve the above-mentioned problems, the present invention is (1) a tensioning device for pulling up a bolt fastened to an object to be fastened and having a washer inserted therein, the outer surface of the washer being provided with a first male. A screw portion is formed, a hollow cylindrical connecting member is formed at a lower end portion, and the first male screw portion is screwed to an inner peripheral surface of the hollow connecting member except for a top surface. A connection member having a female screw portion, a tension mechanism for pulling the connection member in a state where the first male screw portion is screwed to the first female screw portion, and a tension mechanism disposed around the outer periphery of the connection member. A tension receiving portion that receives a reaction force acting from the object to be fastened during tensioning by the tensioning mechanism, wherein the first male screw portion and the first female screw portion are screwed together to perform the pulling. At the time of starting tension to be started, a part other than the head of the bolt or By contacting the washer with the connection member, the first male screw portion having a length equal to or more than one circumference of the outer peripheral surface of the washer, which is a predetermined tension start condition, is screwed into the first female screw portion. And satisfying that there is a clearance between a lower end portion of the connection member and the object to be fastened.

  (2) A tensioning device for pulling up a bolt fastened to an object to be fastened and having a washer and a nut inserted therein, wherein a first male screw portion is formed on an outer peripheral surface of the washer, and a lower end is provided. A connection member having a hollow cylindrical connection member formed at the portion, and a first female screw portion with which the first male screw portion is screwed is formed on an inner peripheral surface of the connection member hollow portion except for a top surface. A tension mechanism for pulling the connection member in a state in which the first male screw portion is screwed to the first female thread portion, and a tension mechanism disposed around an outer periphery of the connection member; A tension receiving portion that receives a reaction force acting from a fastening body, wherein the washer is narrowly pressed by the nut and the fastened body, and the first male screw portion and the first female screw portion are At the time of starting pulling to start the pulling by screwing, A portion other than the top surface of the socket, one of the bolt and the washer is brought into contact with the connection member, so that the length of the outer circumferential surface of the washer, which is a predetermined tension start condition, is one or more rounds. The first male screw part having the first male screw part is screwed to the first female screw part, and a clearance is provided between a lower end of the connection member and the object to be fastened.

  (3) The tensioning mechanism includes a tension rod, a bearing that rotatably supports the tension rod around a shaft extending vertically, and a rotation mechanism for rotating the tension rod around the shaft. The connection member has an upper end provided with a convex portion having a second male screw portion formed on an outer peripheral surface thereof, and a lower end portion of the tension rod screwed with the second male screw portion. The tension device according to the above (1) or (2), wherein a hollow portion having a second female screw portion to be formed on an inner peripheral surface is formed.

  (4) The convex portion has substantially the same shaft diameter as the bolt, and a friction torque reducing material for reducing friction torque is applied to the second male screw portion and the second female screw portion. The tension device according to any one of the above (1) to (3).

  (5) The tension device according to any one of (1) to (4), wherein the connection member has a higher tensile strength than the bolt.

  (6) The tension device according to any one of (1) to (5), wherein the first male screw portion has a length equal to or more than one circumference of an outer peripheral surface of the washer.

  ADVANTAGE OF THE INVENTION According to this invention, the female screw part of a tension | pulling device can be screwed to the male screw part formed in the outer peripheral surface of the washer, and a bolt can be pulled (in other words, a bolt is pulled through a washer). Accordingly, it is possible to suppress a decrease in detection accuracy such as axial force detection due to an insufficient circumferential length of the screw to be screwed.

It is a schematic diagram of a tension device (1st Embodiment). It is a perspective view of a bolt (1st Embodiment). It is a perspective view of a washer (2nd Embodiment). It is a schematic diagram of a tension device (2nd embodiment). It is the schematic of the tension device (the modification 4 of 2nd Embodiment). It is a perspective view of a washer (the modification 2 of a 2nd embodiment). It is a perspective view of a washer (the modification 3 of a 2nd embodiment). It is a schematic diagram of a tension device (3rd embodiment). It is a schematic diagram of a tension device (4th embodiment). It is a perspective view of a nut (4th embodiment). It is a schematic diagram of a tension device (5th embodiment).

  An embodiment of the present invention will be described with reference to the drawings.

(1st Embodiment)
The tensioning device according to the present embodiment is a device that fastens an object to be fastened with a bolt and a washer, and pulls the bolt through a washer while holding down the upper surface of the object to be fastened. It is used for detecting force), detecting a spring constant of a body to which a bolt is fastened, and the like. The basic concept of axial force detection is the same as that described in Japanese Patent No. 4028254. In the following embodiments, the configuration and operation of the tension device will be described by taking axial force detection as an example.

  FIG. 1 is a schematic diagram of the tension device of the present embodiment, and shows a state immediately after the operation of pulling the washer has started. In addition, the boundary between members is clarified by expressing a plurality of members included in the tension device with different types of hatching. FIG. 2 is a perspective view of the bolt.

  The tensioning device 1 includes a connecting member 2, a tensioning mechanism 3, a tension receiver 4, and a handle 5. Note that X indicated by a dashed line indicates a rotation axis of the tensioning device 1 extending in the up-down direction.

  The connection member 2 includes a cylindrical portion 21 and a convex portion 22 formed on the upper surface of the cylindrical portion 21. At the lower end of the cylindrical portion 21, a connecting member hollow portion 21a extending in the vertical direction is formed. The connecting member hollow portion 21a has an upper and lower two-stage configuration including a large-diameter hollow portion 211a and a small-diameter hollow portion 212a, and an upper end of the large-diameter hollow portion 211a and a lower end of the small-diameter hollow portion 212a are connected. The large-diameter hollow portion 211a is formed with a first female screw portion 21a1 that is screwed into the first male screw portion 11a of the washer 11 when an axial force is detected.

  The convex portion 22 is formed in a cylindrical shape having a smaller diameter than the cylindrical portion 21, and a second male screw portion 22 a extending around the rotation axis X is formed on an outer peripheral surface thereof. For the connecting member 2, a material having a higher tensile strength than the bolt 10 can be used. This can suppress plastic deformation of the connection member 2 at the time of detecting the axial force.

  The tension mechanism 3 includes a tension rod 31, a bearing 32, a square drive 33 (corresponding to a rotation mechanism), and a wrench 34 (corresponding to a rotation mechanism). The tension rod 31 includes a cylindrical small-diameter rod portion 31a and a cylindrical large-diameter rod portion 31b, and the upper end of the small-diameter rod portion 31a and the lower end of the large-diameter rod portion 31b are connected to each other. These small-diameter rod portion 31a and large-diameter rod portion 31b are integrally formed.

  At the lower end of the small-diameter rod portion 31a, a tension rod hollow portion 311 extending in the vertical direction is formed. On the inner peripheral surface of the tension rod hollow portion 311, a second female screw portion 311a extending around the rotation axis X is formed. Are formed. A mounting opening 312 is formed at the upper end of the large-diameter rod 31b.

  The bearing portion 32 is a thrust bearing, and rotatably supports the small-diameter rod portion 31a of the tension rod 31. The upper end surface of the bearing portion 32 is in contact with the lower end surface of the large diameter rod portion 31 b of the tension rod 31, and the lower end surface of the bearing portion 32 is in contact with the upper end surface of the tension receiving portion 4. That is, the bearing portion 32 is sandwiched between the large-diameter rod portion 31b and the tension receiving portion 4 in the vertical direction.

  The square drive 33 is detachably attached to the mounting opening 312 of the large-diameter rod portion 31b. By rotating the square drive 33, the tension rod 31 can be rotated around the rotation axis X. The corner drive 33 can be rotated using the handle 5 and the wrench 34. In the configuration of the present embodiment, when the tension rod 31 is rotated once around the rotation axis X using the wrench 34, the connection member 2 moves upward by the screw pitch of the second female screw portion 311a of the tension rod 31. Designed. In the present embodiment, the tension rod 31 is rotated using the square drive 33, the handle 5, and the wrench 34. However, the present invention is not limited to this, and power for rotating the tension rod 31 may be generated. Other possible driving means can also be used.

  The wrench 34 is formed to be long in the horizontal direction, and can obtain a larger torque than the handle 5 when rotated with the same force. The wrench 34 is provided with an angle sensor (for example, a gyro sensor) not shown. The rotation amount of the tension rod 31 can be measured by the angle sensor. However, the angle sensor may be directly attached to the tension rod 31 instead of the wrench 34.

  The tension receiver 4 is provided with an axial force detector (not shown) for detecting the axial force. For example, a strain gauge can be used for the axial force detection unit. The strain gauge is deformed when a force is applied, and outputs an electric signal according to the amount of the deformation. A tension hollow portion 41 extending in the vertical direction is formed at the lower end of the tension receiving portion 4. The connection member 2 is accommodated inside the tension hollow portion 41, and the cylindrical portion 21 of the connection member 2 is arranged along the inner peripheral surface of the tension hollow portion 41. That is, the tension receiving portion 4 is disposed so as to surround the connection member 2.

  Here, the configuration of the pulling mechanism 3 is not limited to the above-described configuration, but may be another configuration as long as the connecting member 2 can be moved upward without rotating when detecting the axial force. For example, a concave portion having an internal thread on the inner peripheral surface is formed on the upper surface of the cylindrical portion 21, and a convex portion having a male screw formed on the outer peripheral surface at the lower end of the tension rod 31 (that is, the lower end of the small diameter rod portion 31 a). And the connection member 2 may be pulled by screwing the convex portion to the female screw. Further, the axial force may be detected by measuring not the rotation operation by the tension rod 31 but the tensile force by the hydraulic pressure and the amount of vertical displacement.

  Next, the bolt, the washer, and the object to be fastened will be described in detail. The bolt 10 is a hexagonal bolt with a flange and includes a bolt shaft 10a, a bolt head 10b, and a bolt flange 10c. A male screw is formed on the bolt shaft 10a. The bolt flange 10c is formed so as to project radially from the lower end of the bolt head 10b, and is formed integrally with the bolt head 10b. The outer diameter of the bolt flange portion 10c is larger than the inner diameter of the small-diameter hollow portion 212a and smaller than the inner diameter of the large-diameter hollow portion 211a.

  The washer 11 is formed in a flat plate shape, and has a larger diameter dimension than the bolt 10. A first male screw portion 11a is formed on the outer peripheral surface of the washer 11 so as to extend in the circumferential direction. The washer 11 is narrowly pressed by the bolt flange portion 10c and the object H1 in the vertical direction. The use of the washer 11 increases the contact area, so that the contact surface pressure against the object H1 can be reduced. Therefore, the present invention can be applied to a case where the object H1 is made of a low-strength material (for example, aluminum).

  Axial force detection can be performed in a state where the first male screw portion 11a of the washer 11 is screwed into the first female screw portion 21a1 of the connection member 2. Here, since the first male screw portion 11a is formed on the outer peripheral surface of the washer 11 that protrudes radially outward from the bolt head 10b, the first male screw portion 11a is formed when the washer 11 and the connecting member 2 are screwed together. A sufficient circumferential length can be ensured. Thereby, it is possible to suppress a decrease in the detection accuracy of the axial force detection due to the plastic deformation of the screw thread at the time of the axial force detection.

  The fastened body H is composed of fastened bodies H1 and H2 superposed in the vertical direction, and the fastened bodies H1 and H2 are formed with bolt holes H1a and H2a, respectively. On the peripheral surface of the bolt hole H2a, a female screw portion to be screwed with the male screw portion of the bolt shaft portion 10a is formed. The bolt 10 inserted into the bolt hole H1a is screwed into the bolt hole H2a, so that the bolt 10 is fastened to the object H.

  The bolt 10 is inserted into the bolt holes H1a and H2a without forming a female screw portion in the bolt hole H2a, and a nut (not shown) is attached to the bolt shaft portion 10a protruding downward from the end surface of the fastened body H (H2). The bolt 10 may be fastened to the fastened body H by screwing.

  Here, the friction torque of the bolt 10 with respect to the object H is set to be larger than the friction torque of the connection member 2 with the tension rod 31. That is, the friction torque between the male screw portion of the bolt shaft portion 10a in the fastened state and the female screw portion of the bolt hole H2a is equal to the second male screw portion 22a of the convex portion 22 in the screwed state and the second torque of the tension rod 31. It is larger than the friction torque with the female screw portion 311a. Thereby, it is possible to prevent the bolt 10 from rotating when the axial force is detected.

  In the present embodiment, in order to realize the magnitude relationship of the friction torque described above, the diameters of the bolt shaft portion 10a and the convex portion 22 are set to be substantially the same, and a lubricant (corresponding to a friction torque reducing material) is used. By applying, the friction torque of the convex portion 22 with respect to the second female screw portion 311a of the tension rod 31 is reduced. Here, as another method, a method of reducing the friction torque by making the diameter of the convex portion 22 smaller than the diameter of the bolt shaft portion 10a is also conceivable. However, when the diameter of the protrusion 22 is reduced, the stress increases during tension, and the protrusion 22 may be damaged. Therefore, in the present embodiment, the bolts 10a and the protrusions 22 are set to have substantially the same diameter, and the friction torque between the protrusions 22 and the tension rod 31 is reduced by using a lubricant. The relationship between the magnitudes of the friction torques is realized.

  Next, the operation of the tension device 1 when detecting the axial force will be described. In the initial state, it is assumed that the bolt 10 and the washer 11 are fastened to the body H to be fastened. The tension mechanism 3, the tension receiving portion 4, and the handle 5 are preassembled and unitized.

First, the first male screw portion 11a of the washer 11 is screwed into the first female screw portion 21a1 of the connection member 2, and the connection member 2 and the washer 11 are connected. Here, when the first male screw portion 11a and the first female screw portion 21a1 are screwed together to start pulling, it is necessary to satisfy a predetermined pulling start condition. The predetermined tension start condition includes the following conditions (1) and (2).
(Condition 1): The first female screw portion 21a1 is screwed into the first male screw portion 11a having a length of at least one circumference of the outer peripheral surface of the washer 11. (Condition 2): Fastened to the lower end portion of the connection member 2 Clearance between body H1

If the condition 1 is not satisfied, a region where no tensile force is applied in the circumferential direction of the washer 11 (in other words, a region that does not abut on the first female screw portion 21a1) occurs, so that the load is applied in the tensile direction (that is, in the vertical direction). It works in a direction different from that of the above, and the accuracy of the axial force detection may be reduced.
If Condition 1 is not satisfied, the thread may be plastically deformed at the time of tension, and the detection accuracy such as the detection of axial force may be reduced.

  When the condition 2 is not satisfied, the axial force detection is performed in a state where the lower end of the connection member 2 is pressed against the workpiece H1, so that the detection error increases.

  Since the washer 11 has a smaller height dimension than the nut and the bolt, when the first male screw portion 11a and the first female screw portion 21a1 are screwed together, the screwing length is insufficient, and the condition 1 is satisfied. There is a possibility that the lower end of the connection member 2 is pressed against the fastened member H1 and the condition 2 is not satisfied.

  Here, when connecting the connection member 2 and the washer 11, the connection member 2 is rotated around the rotation axis X, and the first male screw portion 11 a and the first female screw portion 21 a 1 are screwed together. Screw. When the connection member 2 is further rotated around the rotation axis X, the bolt flange portion 10c (corresponding to “a portion other than the head portion of the bolt” according to claim 1) contacts the top surface of the large-diameter hollow portion 211a. Thus, the connection member 2 cannot rotate. In the present embodiment, when the large-diameter hollow portion 211a and the bolt flange portion 10c come into contact with each other (in other words, when the connection member 2 cannot be screwed), the connection is performed so that the conditions 1 and 2 are satisfied. The size of the large-diameter hollow portion 211a and the small-diameter hollow portion 212a of the member 2 is set. Therefore, Condition 1 and Condition 2 can be easily satisfied.

  Next, the lower end of the tension rod hollow portion 311 is positioned at the tip of the projection 22 of the connection member 2. At this time, the tension receiver 4 is located above the object H1 (in other words, the tension receiver 4 and the object H1 are not in contact with each other). Subsequently, the handle 5 is manually rotated about the rotation axis X, and the second female screw portion 311a and the second male screw portion 22a are screwed together. When the handle 5 is further rotated, the tension rod 31 is screwed downward together with the bearing portion 32 and the tension receiving portion 4, and the tension receiving portion 4 is seated on the object H1.

  FIG. 1 shows a state immediately after the tension receiving portion 4 abuts on the fastened body H1, and a clearance S1 is formed between a lower end portion of the tension rod 31 and an upper end portion of the cylindrical portion 21. I have. A clearance S2 larger than the clearance S1 is formed between the tip of the projection 22 and the upper end of the tension rod hollow portion 311.

  When the tension receiving portion 4 is seated on the object H1, the torque is small by the manual operation using the handle 5, so that the tension rod 31 cannot be further rotated. Then, the tension rod 31 is rotated by a manual operation using the wrench 34. Thereby, the connection member 2 can be moved upward. Note that the connection member 2 does not rotate when moving upward.

  When the connecting member 2 moves upward, a pressing force acts on the tension receiving portion 4 from the large-diameter rod portion 31 b via the bearing portion 32. On the other hand, since the tension receiving portion 4 seated on the object H1 cannot move downward, the pressure is narrowed by the bearing portion 32 and the object H1, and the tension receiving portion 4 is moved from the object H1 to the tension receiving portion 4. Reaction force works. At this time, an electric signal (for example, voltage) is output from the strain gauge, and the axial force can be calculated based on the output signal. In addition, the calculated axial force can be displayed on a display unit (not shown) provided on the outer peripheral surface of the wrench 34 or the tension receiving unit 4, for example. Further, since the clearance S2 is larger than the clearance S1, it is possible to prevent the protrusion 22 from contacting the upper end of the tension rod hollow portion 311 before the cylindrical portion 21 contacts the small diameter rod portion 31a. That is, since a sufficient operating length for pulling the bolt 10 can be secured, it is possible to prevent the axial force from being undetectable.

  As described above, in the present embodiment, the first male screw portion 11a formed on the side surface of the washer 11 is screwed into the connection member 2, and the bolt 10 is pulled through the washer 11, so that the washer is used. As long as the bolt has a flange, the axial force of the bolt can be detected regardless of the shape of the bolt head. Accordingly, a plurality of flanged bolts having different head shapes, such as a hexagonal bolt, a hexagonal bolt, a hexagonal round head bolt, and a square bolt, can be pulled by the same tensioning device to detect the axial force.

  Further, since the contact surface pressure is reduced for the washer 11 and the function as the screwing member for detecting the axial force is also used, it is necessary to use another screwing member different from the washer for detecting the axial force. Absent. Therefore, an increase in the number of parts can be suppressed.

(Modification of First Embodiment)
In the first embodiment, the bolt flange portion 10c is formed in a flat plate shape. However, the present invention is not limited to this. If the diameter of the bolt flange portion 10c is increased radially outward from the bolt head portion 10b, a shape other than a flat plate is used. There may be. For example, the bolt flange portion 10c may have a shape having a curved surface as shown in FIG. In this case, the large diameter hollow portion 211a and the small diameter hollow portion 211a of the connecting member 2 are set so as to satisfy the conditions 1 and 2 when they come into contact with the curved surface (corresponding to a portion other than the head portion of the bolt) of the bolt flange portion. The shape of the portion 212a may be formed.

(2nd Embodiment)
This embodiment differs from the first embodiment in the shapes of washers and bolts. FIG. 3 is a perspective view of the washer of the present embodiment, and FIG. 4A is a schematic diagram of a tension device 100 of the present embodiment. Elements common to the first embodiment are denoted by the same reference numerals. The washer 81 is a stepped washer, and includes a large-diameter washer 81a and a small-diameter washer 81b formed on the upper surface of the large-diameter washer 81a. The large-diameter washer 81a is formed integrally with the small-diameter washer 81b, and has a smaller outer diameter than the small-diameter washer 81b.

  The bolt 82 is a hexagonal bolt including a bolt head portion 82a and a bolt shaft portion 82b, and differs from the bolt 10 of the first embodiment in having no flange portion. A washer 81 is inserted through the bolt shaft 82b, and the washer 81 is interposed between the bolt head 82a and the object H1. The small diameter washer 81b is in contact with the bolt head 82a, and the large diameter washer 81a is in contact with the top surface of the large diameter hollow portion 211a. A first male screw portion 810a is formed on the outer peripheral surface (side surface) of the large diameter washer portion 81a. In the illustrated example, the first male screw portion 810a is formed on the entire outer peripheral surface (side surface) of the large diameter washer portion 81a. However, the present invention is not limited to this, and may be a part of the outer peripheral surface. Good. That is, if the following condition 1 is satisfied, the first male screw portion 810a may be formed on a part of the outer peripheral surface (side surface) of the large diameter washer portion 81a. A gap is formed between the bolt head 82a and the small-diameter hollow portion 212a.

  Next, the operation of the tension device 1 when detecting the axial force will be described. It is assumed that the bolt 10 and the washer 81 are fastened to the fastened body H in the initial state. The tension mechanism 3, the tension receiving portion 4, and the handle 5 are preassembled and unitized.

First, the first male screw portion 810a of the washer 81 is screwed into the first female screw portion 21a1 of the connection member 2 to connect the connection member 2 and the washer 81. Here, when the first male screw portion 810a and the first female screw portion 21a1 are screwed together to start pulling, it is necessary to satisfy a predetermined pulling start condition. The predetermined tension start condition includes the following conditions (1) and (2).
(Condition 1): The first female screw portion 21a1 is screwed into the first male screw portion 810a having a length of one circumference or more of the outer peripheral surface of the large diameter washer portion 81a. (Condition 2): Lower end portion of the connection member 2 A clearance is formed between the object H1 and the object H1. The technical significance of these conditions 1 and 2 is the same as that of the first embodiment, and therefore detailed description is omitted.

  Here, when connecting the connection member 2 and the washer 81, the connection member 2 is rotated around the rotation axis X, and the first male screw portion 810a and the first female screw portion 21a1 are screwed together. Screw. When the connection member 2 is further rotated around the rotation axis X, the large-diameter washer portion 81a contacts the top surface of the large-diameter hollow portion 211a, and the connection member 2 cannot rotate. In the present embodiment, when the large-diameter hollow portion 211a and the large-diameter washer portion 81a come into contact with each other (in other words, when the connection member 2 cannot be screwed), the conditions 1 and 2 are satisfied. The large-diameter hollow portion 211a and the small-diameter hollow portion 212a of the connection member 2 are set in size. Therefore, Condition 1 and Condition 2 can be easily satisfied.

  Other configurations and effects described in the first embodiment can also be obtained in the present embodiment. This point will not be described because the description is redundant.

(Modification 1 of Second Embodiment)
Instead of the washer 81, a washer 91 can be used. FIG. 5A is a perspective view of the washer 91. The washer 91 is a rosette washer, and a first male screw portion 910a is formed on an outer peripheral surface (side surface) of the lower end flat plate portion 91a. In the illustrated example, the first male screw portion 910a is formed on the entire outer peripheral surface (side surface) of the lower end flat plate portion 91a. However, the present invention is not limited to this, and may be a part of the outer peripheral surface. . That is, as long as Condition 1 is satisfied, the first male screw portion 910a may be formed on a part of the outer peripheral surface (side surface) of the lower end flat portion 91a. A curved surface portion 91b that extends upward in a dome shape is formed on the lower end flat plate portion 91a.

  In this modification, when the curved surface portion 91b of the washer 91 and the large-diameter hollow portion 211a come into contact with each other (in other words, when the connection member 2 cannot be screwed), the conditions 1 and 2 are satisfied. The large-diameter hollow portion 211a and the small-diameter hollow portion 212a of the connection member 2 are set in size. Therefore, Condition 1 and Condition 2 can be easily satisfied.

  However, the shape of the connection member 2 is not limited to the shape described above. For example, the large-diameter hollow portion 211a and the small-diameter hollow portion 212a may be connected in an R shape instead of a right angle shape.

(Modification 2 of Second Embodiment)
When the diameter of the small-diameter washer portion 81b is increased and the small-diameter washer portion 81b and the large-diameter hollow portion 211a come into contact with each other (in other words, when the connection member 2 cannot be screwed), the conditions 1 and 2, the large-diameter hollow portion 211a and the small-diameter hollow portion 212a of the connection member 2 may be set in size.

(Modification 3 of Second Embodiment)
Instead of the washer 81, a washer 93 can be used. FIG. 5B is a perspective view of the washer 93. The washer 93 is a normal flat washer formed in a flat plate shape, and a first male screw portion 930a is formed on an outer peripheral surface (side surface) of the washer 93. In the illustrated example, the first male screw portion 930a is formed on the entire outer peripheral surface (side surface) of the washer 93, but the present invention is not limited to this, and may be a part of the outer peripheral surface. That is, if the above condition 1 is satisfied, the first male screw portion 930a may be formed on a part of the outer peripheral surface (side surface) of the washer 93.

  In the present modification, when the upper surface 93a of the washer 93 and the large-diameter hollow portion 211a come into contact with each other (in other words, when the connection member 2 cannot be screwed), the conditions 1 and 2 are satisfied. The large diameter hollow portion 211a and the small diameter hollow portion 212a of the connection member 2 are formed. Therefore, Condition 1 and Condition 2 can be easily satisfied. However, the shape of the connection member 2 is not limited to the shape described above. For example, the large-diameter hollow portion 211a and the small-diameter hollow portion 212a may be connected in an R shape instead of a right angle shape.

(Modification 4 of Second Embodiment)
With reference to FIG. 4B, a tension device 100 'of the present embodiment will be described. FIG. 4B corresponds to FIG. 1 and shows a state immediately after the tension receiving portion 4 has come into contact with the workpiece H1. In the connection member 2 of the present embodiment, a middle diameter hollow portion 213a is formed between the large diameter hollow portion 211a and the small diameter hollow portion 212a.

  Here, when the connecting member 2 is rotated around the rotation axis X to screw the first male screw portion 810a and the first female screw portion 21a1, the connecting member 2 advances downward. When the connection member 2 is further rotated around the rotation axis X, the small-diameter washer portion 81b contacts the medium-diameter hollow portion 213a, and the connection member 2 cannot rotate. In the present embodiment, when the small-diameter washer portion 81b and the middle-diameter hollow portion 213a come into contact with each other (in other words, when the connecting member 2 cannot be screwed), the condition 1 (one or more rounds of the outer peripheral surface of the washer 81) is satisfied. Condition 1 (the first female screw portion 21a1 is screwed into the first male screw portion 810a having a length) and Condition 2 (a clearance is formed between the lower end portion of the connection member 2 and the object H1). The sizes of the large-diameter hollow portion 211a, the medium-diameter hollow portion 213a, and the small-diameter hollow portion 212a are set so as to satisfy the following. Therefore, Condition 1 and Condition 2 can be easily satisfied.

(Third embodiment)
The tension device 200 of the present embodiment will be described with reference to FIG. FIG. 6 corresponds to FIG. 1 and shows a state immediately after the tension receiving portion 4 has come into contact with the fastened body H1. Note that a detailed description of the same configuration as the first embodiment and the second embodiment is omitted. The bolt 82 of the present embodiment is a hexagonal bolt similarly to the second embodiment. The bolt head 82a contacts the lower surface of the object H2, and the tip of the bolt head 82a protrudes from the upper surface of the object H1. That is, the direction of the bolt is opposite to that of the first embodiment. The bolt holes H1a and H2a are not threaded.

  The washer 11 is inserted into the projecting portion of the bolt shaft portion 82b, and the nut 50 is fastened from above the washer 11. That is, the washer 11 is narrowed by the fastening member H <b> 1 and the nut 50. The outer diameter of the washer 11 is set to be larger than that of the nut 50.

  The first male screw portion 11a is formed on the outer peripheral surface of the washer 11, as in the first embodiment. At the lower end of the connection member 2, a connection member hollow portion 21a having a cantilevered shape is formed. A first female screw portion 21a1 is formed on the inner peripheral surface of the lower end of the connection member hollow portion 21a.

  Here, when the connecting member 2 is rotated around the rotation axis X to screw the first male screw portion 11a and the first female screw portion 21a1, the connecting member 2 advances downward. When the connection member 2 is further rotated around the rotation axis X, the top surface of the connection member hollow portion 21a contacts the upper end of the bolt shaft portion 82b, and the connection member 2 cannot rotate. In this embodiment, when the bolt shaft portion 82b and the connection member hollow portion 21a come into contact with each other (in other words, when the connection member 2 cannot be screwed), the condition 1 (one or more rounds of the outer peripheral surface of the washer 11) is satisfied. Condition 1 (the first female screw portion 21a1 is screwed into the first male screw portion 11a having a length) and Condition 2 (a clearance is formed between the lower end portion of the connection member 2 and the object H1). The size of the connection member hollow portion 21a is set so as to satisfy the following. Therefore, Condition 1 and Condition 2 can be easily satisfied.

(Fourth embodiment)
The tension device 300 according to the present embodiment will be described with reference to FIGS. FIG. 7 corresponds to FIG. 1 and shows a state immediately after the tension receiving portion 4 has come into contact with the workpiece H1. FIG. 8 is a perspective view of the nut 95 of the present embodiment. Detailed description of the same configuration as the first embodiment and the third embodiment will be omitted.

  This embodiment differs from the third embodiment in the shape of the nut 95 and the shape of the connection member 2. The nut 95 is a nut with a flange, and includes a nut flange portion 95a and a nut main body 95b. The nut flange 95a projects radially outward from the lower end of the nut body 95b. The outer diameter of the nut flange portion 95a is set smaller than the outer diameter of the washer 11.

  Here, when the connecting member 2 is rotated around the rotation axis X to screw the first male screw portion 11a and the first female screw portion 21a1, the connecting member 2 advances downward. When the connecting member 2 is further rotated around the rotation axis X, the nut flange portion 95a contacts the large-diameter hollow portion 211a, and the connecting member 2 cannot rotate. In the present embodiment, when the nut flange portion 95a and the large-diameter hollow portion 211a come into contact with each other (in other words, when the connection member 2 cannot be screwed), the condition 1 (one or more rounds of the outer peripheral surface of the washer 11) is satisfied. Condition 1 (the first female screw portion 21a1 is screwed into the first male screw portion 11a having a length) and Condition 2 (a clearance is formed between the lower end portion of the connection member 2 and the object H1). The sizes of the large-diameter hollow portion 211a and the small-diameter hollow portion 212a are set so as to satisfy the following. Therefore, Condition 1 and Condition 2 can be easily satisfied.

(Modification of Fourth Embodiment)
In the fourth embodiment, the nut flange portion 95a is formed in a flat plate shape. However, the present invention is not limited to this, and the nut flange portion 95a may have a shape other than the flat plate, which is expanded radially outward from the nut main body 95b. . The nut flange portion 95a may have, for example, a shape having a curved surface as shown in FIG. In this case, the large-diameter hollow portion 211a and the small-diameter hollow portion of the connection member 2 meet the conditions 1 and 2 when they come into contact with the curved surface of the nut flange portion (corresponding to a portion other than the top surface of the nut). The shape of the portion 212a may be formed. However, the shape of the connection member 2 is not limited to the shape described above. For example, the large-diameter hollow portion 211a and the small-diameter hollow portion 212a may be connected in an R shape instead of a right angle shape.

(Fifth embodiment)
The tension device 400 according to the present embodiment will be described with reference to FIG. FIG. 9 corresponds to FIG. 1 and shows a state immediately after the tension receiving portion 4 has come into contact with the workpiece H1. This embodiment differs from the fourth embodiment in the shapes of the nut and the washer. The nut 97 of the present embodiment is a nut without a flange. The washer of the present embodiment is the same as the washer 81 of the second embodiment. In the connecting member 2 of the present embodiment, a middle diameter hollow portion 213a is formed between the large diameter hollow portion 211a and the small diameter hollow portion 212a.

  Here, when the connecting member 2 is rotated around the rotation axis X to screw the first male screw portion 810a and the first female screw portion 21a1, the connecting member 2 advances downward. When the connecting member 2 is further rotated around the rotation axis X, the large-diameter washer portion 81a contacts the large-diameter hollow portion 211a, and the connecting member 2 cannot be rotated. In the present embodiment, when the large-diameter washer portion 81a and the large-diameter hollow portion 211a come into contact with each other (in other words, when the connecting member 2 cannot be screwed), the condition 1 (one or more rounds of the outer peripheral surface of the washer 81) is used. Condition that the first female screw portion 21a1 is screwed into the first male screw portion 810a having a length of (2) and that the clearance is formed between the lower end portion of the connection member 2 and the object H1. The sizes of the large-diameter hollow portion 211a and the small-diameter hollow portion 212a are set so as to satisfy ()). Therefore, Condition 1 and Condition 2 can be easily satisfied.

(Modification 1 of Fifth Embodiment)
When the height of the large-diameter hollow portion 211a is increased and the small-diameter washer portion 81b and the medium-diameter hollow portion 213a come into contact with each other (in other words, when the connecting member 2 cannot be screwed), the conditions 1 and 2 are satisfied. 2, the large-diameter hollow portion 211a, the small-diameter hollow portion 212a, and the medium-diameter hollow portion 213a of the connection member 2 may be set in size.

(Modification 2 of Fifth Embodiment)
In the fifth embodiment, the washer 81 including the large-diameter washer portion 81a and the small-diameter washer portion 81b is used. However, the present invention is not limited to this. For example, a flat washer as illustrated in FIG. It can also be used. In this case, when the upper surface of the flat washer contacts the large-diameter hollow portion 211a, the shapes of the large-diameter hollow portion 211a and the small-diameter hollow portion 212a of the connection member 2 may be formed so as to satisfy the conditions 1 and 2. . In this case, the middle diameter hollow portion 213a can be omitted.

1 100 100 '200 300 400 Tensioning device 2 Connection member 3 Tension mechanism 4 Tension receiving portion 5 Handle 10 Bolt 10a Bolt shaft portion 10b Bolt head portion 10c Bolt flange portion 11 Washer 11a First male screw portion 21 Column portion 21a Connection member hollow Part 21a1 First female screw part 22 Convex part 22a Second male screw part 31 Tension rod 31a Small diameter rod part 31b Large diameter rod part 32 Bearing part 33 Square drive 34 Wrench 50 Nut 81 Washer 81a Washer large diameter part 81b Washer small diameter part 810a First male screw portion 82 Bolt 91 Washer 91a Lower flat plate portion 91b Curved surface portion 910a Curved surface portion 93 Washer 95 Nut 95a Nut flange portion 95b Nut body 311 Tension rod hollow portion 311a Second female screw portion H (H1, H2)

Claims (6)

A tension device that is fastened to an object to be fastened and pulls a bolt through which a washer is inserted upward,
A first male screw portion is formed on an outer peripheral surface of the washer,
A connection in which a hollow cylindrical connecting member is formed at a lower end portion, and a first female screw portion with which the first male screw portion is screwed is formed on an inner peripheral surface of the hollow connecting member except for a top surface. Components,
A tension mechanism that pulls the connection member in a state where the first male screw portion is screwed to the first female screw portion;
A tension receiving portion that is arranged around the outer periphery of the connection member and receives a reaction force acting from the object to be fastened during tension by the tension mechanism;
Has,
By screwing the first male screw portion and the first female screw portion, at the time of starting tension to start the pulling, by contacting a part other than the head of the bolt or the washer with the connection member. Screwing the first male screw portion having a length of at least one circumference of the outer peripheral surface of the washer to the first female screw portion, which is a predetermined tension start condition, and a lower end portion of the connection member. A tension device that satisfies that there is a clearance between the object and the object to be fastened. A tension device that is fastened to an object to be fastened and pulls up a bolt through which a washer and a nut are inserted,
A first male screw portion is formed on an outer peripheral surface of the washer,
A connection in which a hollow cylindrical connecting member is formed at a lower end portion, and a first female screw portion with which the first male screw portion is screwed is formed on an inner peripheral surface of the hollow connecting member except for a top surface. Components,
A tension mechanism that pulls the connection member in a state where the first male screw portion is screwed to the first female screw portion;
A tension receiving portion that is arranged around the outer periphery of the connection member and receives a reaction force acting from the object to be fastened during tension by the tension mechanism;
Has,
The washer is narrowly pressed by the nut and the object to be fastened,
At the time of starting the tension for starting the pulling by screwing the first male screw portion and the first female screw portion, any one of a portion of the nut other than the top surface, the bolt and the washer Is brought into contact with the connection member, thereby screwing the first male screw portion having a length equal to or more than one circumference of the outer peripheral surface of the washer, which is a predetermined tension start condition, to the first female screw portion, And a tension device that satisfies a clearance between a lower end portion of the connection member and the object to be fastened. The tensioning mechanism has a tension rod, a bearing that rotatably supports the tension rod around a shaft extending vertically, and a rotation mechanism for rotating the tension rod around the shaft.
At the upper end of the connection member, a convex portion having a second male screw portion formed on the outer peripheral surface is provided,
The hollow part which has the 2nd female screw part screwed with the said 2nd male screw part in the lower peripheral part of the said tension rod in an inner peripheral surface is formed, The Claim 1 or 2 characterized by the above-mentioned. Tension device.   The tension device according to claim 3, wherein the tension receiving portion is vertically sandwiched between the bearing portion and the object to be fastened.   The convex portion has a shaft diameter substantially equal to that of the bolt, and a friction torque reducing material for reducing friction torque is applied to the second male screw portion and the second female screw portion. Item 5. The tension device according to item 3 or 4. The tension device according to claim 1, wherein the connection member has a higher tensile strength than the bolt.