JP6381841B1 - Tensioning device - Google Patents

Abstract

An object of the present invention is to reduce errors such as axial force detection by screwing a tensioning device into a portion different from a shaft portion of a bolt and pulling the bolt.
A tension device 1 for pulling upward a bolt 10 that is fastened to a body to be fastened H and through which a washer 11 is inserted. A first male screw portion 11a is formed on an outer peripheral surface of the washer 11. The connecting member 2 having a first female screw portion 21a1 into which the first male screw portion 11a is screwed, and the first male screw portion 11a being screwed into the first female screw portion 21a1 A tension mechanism 3 that pulls the connection member 2; and a tension receiving portion 4 that is disposed around the outer periphery of the connection member 2 and that receives a reaction force that acts from the fastened body H during tension by the tension mechanism 3. A tensioning device characterized by that.
[Selection] Figure 1

Description

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

  Fastening using screws is performed for assembling machines such as automobiles and structures such as bridges. The strength of the screw as a fastening body greatly depends on the fastening force. On the other hand, the management of the fastening force in the bolt fastening body is generally only performed at the time of tightening by measuring the torque and the rotation angle, and is hardly performed after the tightening. However, if the bolt loosens due to unexpected external forces during machine operation and the tightening force decreases, the risk of fatigue failure increases significantly. Therefore, in order to prevent a bolt breakage accident and improve the reliability of the screw fastening body, it is necessary to pay attention to the detection of the tightening force of the bolt after fastening.

  In Patent Document 1, a bolt is inserted into an insertion hole of a body to be fastened, and a nut is screwed and fastened to a male screw portion of the bolt that has passed through the insertion hole, whereby a bolt / nut fastening body that narrows the body to be fastened is disclosed. Then, the male threaded portion of the bolt protruding from the upper surface is pulled against the nut upper surface, the transition point of the spring constant of the bolt is detected, and the tensile force at the transition point is used as the tightening force. A method for detecting a tightening force of a bolt / nut fastening body is disclosed.

Japanese Patent No. 4028254

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

  Therefore, the present invention has an object to reduce errors such as axial force detection by screwing a tensioning device into a portion different from the bolt shaft and pulling the bolt.

In order to solve the above problems, the present invention is (1) a tensioning device for pulling upward a bolt fastened to a body to be fastened and having a washer inserted therethrough, on the outer peripheral surface of the washer. In a state in which a threaded portion is formed and the first male threaded portion is screwed with a connecting member having a first female threaded portion with which the first male threaded portion is threaded, A tension mechanism that pulls the connection member; and a tension receiving portion that is disposed around the outer periphery of the connection member and receives a reaction force acting from the fastened body when tensioned by the tension mechanism.

  (2) The tension mechanism includes a tension rod, a bearing portion that supports the tension rod so as to be rotatable around a shaft portion that extends in the vertical direction, and a rotation mechanism that rotates the tension rod around the shaft portion. And a convex portion having a second male screw portion formed on the outer peripheral surface is provided at the upper end portion of the connection member, and the lower end portion of the tension rod is screwed into the second male screw portion. The tension device according to (1) above, wherein a hollow portion having a second female screw portion on the inner peripheral surface is formed.

  (3) The tension device according to (2), wherein the tension receiving portion is sandwiched between the bearing portion and the fastened body in the vertical direction.

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

  (5) The tension device according to any one of (1) to (4), wherein the connection member has 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 longer than one circumference of the outer peripheral surface of the washer.

  According to the present invention, it is possible to pull the bolt (in other words, pull the bolt through the washer) by screwing the female screw portion of the tensioning device into the male screw portion formed on the outer peripheral surface of the washer. Thereby, it can suppress that the circumferential direction length of the screw | thread to screw together runs short and detection accuracy, such as axial force detection, falls.

It is the schematic of a tension device. It is a perspective view of a bolt and a washer. It is the schematic of a tension | pulling apparatus (2nd Embodiment).

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

(First embodiment)
The tension device according to the present embodiment is a device that fastens a body to be fastened with a bolt and a washer and pulls the bolt through the washer while suppressing the upper surface of the body to be fastened. Force) detection and detection of the spring constant of the fastened body to which the bolt is fastened. The basic concept of axial force detection is the same as that described in Japanese Patent No. 4028254. In the following embodiments, axial force detection is taken as an example, and the configuration and operation of a tension device will be described.

  FIG. 1 is a schematic view of the tensioning device of the present embodiment, showing a state immediately after the operation of pulling the washer is started. In addition, the boundary between members is clarified by expressing the several member contained in a tension | pulling apparatus with a mutually different kind of hatching. FIG. 2 is a perspective view of a bolt and a washer.

  The tension device 1 includes a connection member 2, a tension mechanism 3, a tension receiver 4, and a handle 5. In addition, X shown with a dashed-dotted line has shown the rotating shaft of the tension | pulling apparatus 1 extended to an up-down direction.

  The connecting member 2 includes a cylindrical portion 21 and a convex portion 22 formed on the upper surface of the cylindrical portion 21. A connecting member hollow portion 21 a extending in the vertical direction is formed at the lower end portion of the cylindrical portion 21. A first female screw portion 21a1 extending around the rotation axis X is formed on the peripheral surface of the connecting member hollow portion 21a. 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 the outer peripheral surface thereof. A material having a higher tensile strength than the bolt 10 can be used for the connecting member 2. Thereby, it is possible to suppress the plastic deformation of the connection member 2 when detecting the axial force.

  The tension mechanism 3 includes a tension rod 31, a bearing portion 32, a corner 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 portion of the small-diameter rod portion 31a and the lower end portion of the large-diameter rod portion 31b are connected to each other. The small diameter rod portion 31a and the large diameter rod portion 31b are integrally formed.

  A tension rod hollow portion 311 extending in the vertical direction is formed at the lower end portion of the small diameter rod portion 31a. A second female screw portion 311a extending around the rotation axis X is formed on the inner peripheral surface of the tension rod hollow portion 311. Is formed. A mounting opening 312 is formed at the upper end of the large-diameter rod portion 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 corner drive 33 is detachably attached to the attachment opening 312 of the large-diameter rod portion 31b, and the tension rod 31 can be rotated around the rotation axis X by rotating the corner drive 33. The angular 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 is moved 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 by using the angular 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 drive 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 receiving unit 4 is provided with an unillustrated axial force detection unit for detecting the axial force. For example, a strain gauge can be used for the axial force detection unit. The strain gauge deforms when a force is applied, and outputs an electrical signal corresponding to the amount of deformation. A tension hollow portion 41 extending in the vertical direction is formed at the lower end portion of the tension receiving portion 4. The connection member 2 is accommodated inside the tension hollow portion 41, and the columnar portion 21 of the connection member 2 is disposed 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, and any other configuration may be used as long as the connecting member 2 can be moved up without rotating when detecting the axial force. For example, the convex part which formed the recessed part which has an internal thread in the inner peripheral surface in the upper surface of the cylindrical part 21, and formed the external thread in the outer peripheral surface in the lower end part (namely, lower end part of the small diameter rod part 31a). In addition, the connecting member 2 may be pulled by screwing the convex portion into the female screw. Further, the axial force may be detected by measuring the tensile force due to the hydraulic pressure and the amount of vertical displacement instead of the rotation operation by the tension rod 31.

  Next, a bolt, a washer, and a to-be-fastened body are demonstrated in detail. The bolt 10 is a hexagonal bolt and includes a bolt shaft portion 10a and a bolt head portion 10b. A male screw is formed on the bolt shaft portion 10a. The washer 11 is set to have a diameter larger than that of the bolt 10, and a first male screw portion 11 a is formed on the outer peripheral surface so as to extend in the circumferential direction. The washer 11 is narrowly pressed by the bolt head 10b and the fastened body H1 in the vertical direction. Since the contact area is increased by using the washer 11, the contact surface pressure with respect to the fastened body H1 can be reduced. Therefore, the present invention can also be applied when the fastened body H1 is made of a material having low strength (for example, aluminum).

  The 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 connecting member 2. Here, since the first male screw portion 11a is formed on the outer peripheral surface of the washer 11 projecting radially outward from the bolt head portion 10b, the screw when the washer 11 and the connecting member 2 are screwed together is formed. A sufficient circumferential length can be secured. Thereby, it can suppress that a screw thread deforms plastically at the time of axial force detection, and the detection accuracy of axial force detection falls.

  It is desirable that the first male screw portion 11 a has a length that is at least one round of the outer peripheral surface of the washer 11. When the length of the first male screw portion 11a is less than one turn of the outer peripheral surface of the washer 11, a region where no tensile force is applied in the circumferential direction of the washer 11 (in other words, a region that does not contact the first female screw portion 21a1) ) Occurs, the load acts in a direction different from the pulling direction (that is, the vertical direction), and the accuracy of axial force detection may be reduced.

  The fastened body H is composed of fastened bodies H1 and H2 which are overlapped in the vertical direction, and bolt holes H1a and H2a are formed in the fastened bodies H1 and H2, respectively. On the peripheral surface of the bolt hole H2a, a female screw portion that is 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, whereby the bolt 10 is fastened to the fastened body H.

  The bolt 10 is inserted into the bolt holes H1a and H2a without forming a female thread 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 to the fastened body H is set to be larger than the friction torque of the connection member 2 to the tension rod 31. That is, the friction torque between the male screw portion of the bolt shaft portion 10a in the fastening state and the female screw portion of the bolt hole H2a is the second male screw portion 22a of the convex portion 22 in the screwed state and the second 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 this embodiment, in order to realize the above-described magnitude relationship of the friction torque, the bolt shaft portion 10a and the convex portion 22 are set to have substantially the same diameter, and a lubricant (corresponding to a friction torque reducing material) is used. By applying, the friction torque of the convex part 22 with respect to the 2nd internal thread part 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 can be considered. However, if the diameter of the convex portion 22 is reduced, the stress increases during tension, and the convex portion 22 may be damaged. Therefore, in the present embodiment, the diameter dimensions of the bolt shaft portion 10a and the convex portion 22 are set to be substantially the same, and the friction torque between the convex portion 22 and the tension rod 31 is reduced by using a lubricant, whereby The size relationship of the friction torque is realized.

  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 11 are fastened to the fastened body H in the initial state. Further, it is assumed that the tension mechanism 3, the tension receiving portion 4, and the handle 5 are assembled in advance and unitized.

  First, the first male screw portion 11a of the washer 11 is screwed into the first female screw portion 21a1 of the connecting member 2 to connect the connecting member 2 and the washer 11. Here, if the height dimension of the connecting member hollow portion 21a is small, the upper surface of the bolt head portion 10b is connected to the connecting member before all the screw threads of the first male screw portion 11a are screwed into the first female screw portion 21a1. Since it will contact | abut on the top | upper surface of the hollow part 21a, there exists a possibility that a catch may become inadequate. On the other hand, if the height dimension of the connecting member hollow portion 21a is large, axial force detection is performed in a state where the lower end portion of the connecting member 2 is in pressure contact with the fastened body H1, so that a detection error increases. Therefore, when the connection member 2 and the washer 11 are coupled, all the threads of the first male screw portion 11a are screwed into the first female screw portion 21a1, and the lower end portion of the connection member 2 presses the fastened body H1. In consideration of the total thickness of the bolt head 10b and the washer 11, it is preferable to set the height dimension of the connecting member hollow portion 21a.

  Next, the lower end portion of the tension rod hollow portion 311 is positioned at the tip of the convex portion 22 of the connecting member 2. At this time, the tension receiving portion 4 is located above the fastened body H1 (in other words, the tension receiving portion 4 and the fastened body H1 are not in contact with each other). Subsequently, the handle 5 is manually rotated around 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 fastened body H1.

  FIG. 1 shows a state immediately after the tension receiving portion 4 comes into contact with the fastened body H1, and a clearance S1 is formed between the lower end portion of the tension rod 31 and the upper end portion of the cylindrical portion 21. Yes. A clearance S2 larger than the clearance S1 is formed between the tip of the convex portion 22 and the upper end portion of the tension rod hollow portion 311.

  When the tension receiving portion 4 is seated on the fastened body H1, the tension rod 31 cannot be further rotated because the torque is small in the manual operation with the handle 5. Therefore, the tension rod 31 is rotated manually by the wrench 34. Thereby, the connection member 2 can be moved up. The connecting member 2 does not rotate when moving upward.

  When the connecting member 2 moves up, 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 fastened body H1 cannot move downward, the tension receiving portion 4 is narrowed by the bearing portion 32 and the fastened body H1, and the tightened body H1 is pressed against the tension receiving portion 4. Reaction force works. At this time, an electrical signal (for example, voltage) is output from the strain gauge, and the axial force can be calculated from the output signal. 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 convex portion 22 from coming into contact with the upper end portion of the tension rod hollow portion 311 before the cylindrical portion 21 comes into contact with 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 detection from becoming impossible.

  As described above, in this embodiment, since the first male screw portion 11a formed on the side surface of the washer 11 is screwed to the connecting member 2 and the bolt 10 is pulled via the washer 11, the washer is used. As long as the bolt can be used, the axial force of the bolt can be detected regardless of the shape of the bolt head. Accordingly, a plurality of bolts having different head shapes, such as hexagon bolts, hexagon socket head cap bolts, hexagon socket head cap screws, and square bolts, can be pulled with the same tension device to detect axial force.

  Since the washer 11 has both a reduction in contact surface pressure and a function as a screwing member at the time of axial force detection, it is not necessary to use another screwing member different from the washer for detecting the axial force. Therefore, an increase in the number of parts can be suppressed.

(Second Embodiment)
With reference to FIG. 3, the tensioning device 100 of the present embodiment will be described. FIG. 3 corresponds to FIG. 1 and shows a state immediately after the tension receiving portion 4 comes into contact with the fastened body H1. Note that detailed description of the same configuration as in the first embodiment is omitted. In the bolt 10 of the present embodiment, the bolt head portion 10b contacts the lower surface of the fastened body H2, and the tip of the bolt shaft portion 10a protrudes from the upper surface of the fastened body 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.

  A washer 11 is inserted through the protruding portion of the bolt shaft portion 10a, and a nut 50 is fastened from above the washer 11. That is, the washer 11 is tightly pressed by the fastened body H1 and the nut 50. The washer 11 is set to have a larger outer diameter than the nut 50.

  The point that the first male screw portion 11a is formed on the outer peripheral surface of the washer 11 is the same as in the first embodiment. The connecting member hollow portion 21a has an upper limit two-stage configuration including a large-diameter hollow portion 211a and a small-diameter hollow portion 212a, and the upper end portion of the large-diameter hollow portion 211a and the lower end portion 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 axial force is detected.

  Here, the vertical dimension of the large-diameter hollow portion 211a and the small-diameter hollow portion 212a is such that when the connecting member 2 is screwed to the washer 11, the bolt shaft portion 10a contacts the top surface of the small-diameter hollow portion 212a. The size of the nut 50 is adjusted so that the upper surface of the nut 50 comes into contact with the top surface of the large-diameter hollow portion 211a. Also in the configuration of the present embodiment, the same effect as in the first embodiment can be obtained.

DESCRIPTION OF SYMBOLS 1 100 Pulling device 2 Connecting member 3 Pulling mechanism 4 Tension receiving part 5 Handle 10 Bolt 10a Bolt shaft part 10b Bolt head 11 Washer 11a First male screw part 21 Cylindrical part 21a Connecting member hollow part 21a1 First female screw part 22 Convex Part 22a Second male thread part 31 Tension rod 31a Small diameter rod part 31b Large diameter rod part 32 Bearing part 33 Square drive 34 Wrench 50 Nut 311 Tension rod hollow part 311a Second female thread part H (H1, H2) Fastened body

Claims (6)

A tensioning device for pulling up a bolt fastened to a body to be fastened and having a washer inserted therethrough,
A first male screw portion is formed on the outer peripheral surface of the washer,
Connection in which a bottomed tubular connecting member hollow portion is formed, and a first female screw portion is formed on the inner peripheral surface excluding the top surface of the connecting member hollow portion. Members,
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 connecting member and receives a reaction force acting from the fastened body when pulled by the pulling mechanism;
I have a,
The washer is constricted by the head of the bolt and the fastened body,
At the start of pulling to start the pulling,
The head portion of the bolt is in contact with the top surface of the connecting member hollow portion, and the first male screw portion having a length equal to or longer than one round of the outer peripheral surface of the washer is screwed into the first female screw portion. And a clearance is formed between a lower end portion of the connection member and the fastened body . A tensioning device for pulling up a bolt fastened to a body to be fastened and having a washer inserted therethrough,
A first male screw portion is formed on the outer peripheral surface of the washer,
A ceiling-shaped large-diameter hollow portion formed at the lower end, and a bottomed-cylindrical small-diameter hollow portion formed on the top surface of the large-diameter hollow portion, the top surface of the large-diameter hollow portion A connecting member in which a first female screw portion into which the first male screw portion is screwed is formed on an inner peripheral surface excluding
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 connecting member and receives a reaction force acting from the fastened body when pulled by the pulling mechanism;
Have
The washer is tightly pressed by the nut and the fastened body,
At the start of pulling to start the pulling,
The nut is in contact with the top surface of the large-diameter hollow portion, and the first male screw portion having a length of one or more outer peripheral surfaces of the washer is screwed into the first female screw portion. The tension device is characterized in that a tip of the bolt extends toward the small-diameter hollow portion, and a clearance is formed between a lower end portion of the connection member and the fastened body. The tension mechanism includes a tension rod, a bearing portion that rotatably supports the tension rod in a vertical direction extending in the vertical direction, and a rotation mechanism for rotating the tension rod around the shaft portion.
The upper end portion of the connection member is provided with a convex portion having a second male screw portion formed on the outer peripheral surface,
Wherein the lower end of the tension rod, according to claim 1 or 2, characterized in that hollow portion having a second female threaded portion to be screwed into the second male threaded portion on the inner peripheral surface is formed Tensioning device. The tension device according to claim 3 , wherein the tension receiving portion is sandwiched between the bearing portion and the fastened body in the vertical direction. The shaft diameter of the convex portion is substantially the same as that of the bolt, and a friction torque reducing material that reduces friction torque is applied to the second male screw portion and the second female screw portion. Item 5. A tensioning device according to item 3 or 4 . The tension device according to any one of claims 1 to 5 , wherein the connection member has higher tensile strength than the bolt.