JP2010253659A - Bolt tightening device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bolt tightening device capable of further reducing tightening rotary torque to be imparted when tightening a bolt and enhancing bolt shaft force imparted when tightening the bolt. <P>SOLUTION: This bolt tightening device includes a tightening rotary torque imparting shaft part and a lateral load imparting means for transmitting the rotary torque imparted by the tightening rotary torque imparting shaft part to a bolt head part and imparting a lateral load parallel to a bolt seat surface to the bolt head part. The load imparting means includes a rotary shaft part for transmitting the rotary torque from the tightening rotary torque imparting shaft part to the bolt head part, and an eccentric moving mechanism part provided with an eccentric ring which has an outer peripheral surface and an inner peripheral surface, has a center axis of the outer peripheral surface different from a center axis of the inner peripheral surface, has the inner peripheral surface disposed around the rotary shaft part, and rotates around the center axis of the outer peripheral surface in a direction reverse to a rotating direction of the rotary shaft part when the rotary shaft part is rotated. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a bolt fastening device that is used when fastening each fastened part using a bolt, and in particular, a slip between fastened parts when a shear external force is applied to the fastened part. The present invention relates to a bolt fastening device used when fastening each fastening part to prevent it by friction welding.

  One method for fastening a plurality of parts to be fastened together is to fasten the parts to be fastened to each other using bolts. When using bolts to fasten parts to be fastened to each other, especially when using bolts to prevent slippage between the parts to be fastened when a shear external force is applied by friction bonding between the parts to be fastened. When the components are fastened to each other, it is important to stabilize the axial force in the bolt axis direction (hereinafter referred to as bolt axial force) caused by tightening the bolts. When the bolt axial force provided by tightening the bolt is low, sufficient frictional bonding is not provided between each fastened part, and when the fastened part receives a shear external force, slippage between the fastened parts does not occur. This is likely to cause bolt loosening.

  It is known that a friction coefficient stabilizer is attached to a screw portion of a bolt in order to always stabilize the bolt axial force caused by tightening the bolt (see Patent Document 1). In Patent Document 1, by attaching a friction coefficient stabilizer to a fastening material such as a screw part, the friction coefficient at the time of fastening the screw part can be stabilized, and an arbitrary friction coefficient value can be given. It has been shown that problems such as looseness and breakage of fastening materials such as screw parts can be solved.

JP-A-9-40991 International Publication WO2006 / 126742

  However, when stabilizing the bolt axial force by using a friction coefficient stabilizer as shown in Patent Document 1, there remains a problem in terms of increasing the axial force of the bolt axial force. I think.

  When fastening each component to be fastened with bolts, it is necessary to prevent the screw part from loosening easily after bolt tightening, and at least the screw part must be self-supporting after bolt tightening. I think that it is necessary to satisfy the conditions.

  Here, the expression “the screw part is self-supporting” means that the male screw part and the female screw part are engaged with each other when the male screw part of the bolt is inserted into the female screw part from the vertical direction (hereinafter referred to as “below”). ), Or the friction surface of the bolt head friction surface (hereinafter referred to as the bolt seat surface) is too small to apply rotational torque to the bolt head. It is intended that the bolt is not rotated by its own weight alone or by the bolt axial force.

  In the state where the screw part is not self-supporting, even if the torque is applied to the bolt head and the bolt is tightened, the bolt is tightened when the rotation torque is applied to the bolt head. It is conceivable that the male screw portion and the female screw portion are relatively rotated by the bolt axial force, and the bolt axial force is reduced.

  When attaching a lubricant with an extremely small friction coefficient to the screw part to reduce the friction coefficient of the screw surface itself in order to increase the bolt axial force, the above-mentioned independence of the screw part after bolt tightening is a problem. Therefore, in order to solve this problem, it is considered that a certain restriction is imposed on the reduction of the friction coefficient of the screw surface by the friction coefficient stabilizer depending on the design conditions. Therefore, it is considered that a certain limit is imposed on increasing the axial force of the bolt by using the friction coefficient stabilizer.

  When the components to be fastened are fastened to each other using bolts, the higher the bolt axial force that is brought about during bolt tightening, the stronger the frictional connection between the components to be fastened.

  Therefore, when the parts to be fastened are mutually fastened using bolts in order to prevent slippage between the parts to be fastened when a shear external force is applied, by frictional joining between the parts to be fastened, To find a means that can increase the axial force of the bolt that is brought to the point, and that does not require consideration of the self-supporting of the threaded portion after bolt tightening, that is, a friction coefficient stabilizer. It is considered to be an important issue to find a means that can provide a higher bolt axial force even when used.

  As one solution to this problem, when fastening a fastened body using a bolt, a lateral load parallel to the bolt seat surface is applied to the bolt head to bias the surface pressure of the screw surface and the bolt seat surface. In this state, a bolt tightening method and a bolt tightening device have been proposed in which a rotational torque for rotating the male screw portion of the bolt is applied to the bolt head and the bolt is tightened (see Patent Document 2).

  According to this bolt tightening device, while applying a predetermined lateral load parallel to the bolt seating surface to the bolt head, the bolt headline is tightened by applying a torque to the bolt head and tightening the bolt. While tilting at a very small angle with respect to the normal of the bolt, and tilting it with a predetermined angle, and tilting the bolt head with a very small angle with respect to the bolt seat surface Thus, the bolt can be tightened, so that the surface pressure of the screw surface and the bolt seat surface brought about when the bolt is tightened can be biased to a desired state.

  By deliberately biasing the surface pressure of the screw surface and bolt seating surface that are provided when tightening the bolt to the desired state, the actual rotation center line of the bolt when tightening the bolt is separated from the center axis of the bolt. The screw surface and the bolt seat surface can be moved in the direction of higher surface pressure. This reduces the tightening torque of the bolt, reduces the torsional stress generated in the threaded portion, and stabilizes the bolt axial force to a higher level. Therefore, the bolt axial force can be increased.

  In addition, after the tightening of the bolt is completed and the rotational torque applied to the bolt head is released, the engagement between the male screw portion and the female screw portion is caused by the frictional force generated according to the friction coefficient of the screw surface itself. Can be maintained. As a result, there is no limitation on increasing the axial force due to the self-supporting of the screw, which is a problem when reducing only the friction coefficient in order to increase the axial force of the bolt, and when using a friction coefficient stabilizer together, It is possible to provide a higher bolt axial force.

  According to the present invention, when a body to be fastened is fastened using a bolt, a lateral load parallel to the bolt seat surface is applied to the bolt head to cause the screw surface and the bolt seat surface to slide slightly in the direction perpendicular to the bolt axis. In order to improve the bolt tightening device that tightens the bolt by applying a rotational torque that rotates the male screw part of the bolt to the bolt head, especially reducing the tightening rotational torque applied when tightening the bolt An object of the present invention is to provide a bolt tightening device that can increase the axial force of a bolt that is generated when tightening a bolt.

  According to the first aspect of the present invention, in the bolt fastening device that is used when the fastened body is fastened by using the bolt having the bolt head portion and the bolt shaft portion having the male screw portion, the rotational power source A tightening rotation torque applying shaft portion that is connected to the rotation portion for applying a rotation torque for rotating the male screw portion, and transmits the rotation torque applied by the tightening rotation torque applying shaft portion to the bolt head portion, and the bolt head portion When the male screw part is rotated by the rotational torque transmitted to the side, a lateral load parallel to the bolt seat surface is applied to the screw surface and the bolt seat surface to intentionally slide slightly in the direction perpendicular to the bolt axis. A lateral load applying means for applying to the bolt head, and the lateral load applying means is configured to apply a rotational torque by the tightening rotational torque applying shaft portion when the bolt is tightened. A rotating shaft portion that rotates in the bolt tightening direction, transmits the rotational torque to the bolt head, and rotates the male screw portion in the bolt tightening direction, and an outer peripheral surface and an inner peripheral surface. And an eccentric ring having a different center axis from the inner peripheral surface, and when the inner peripheral surface is disposed around the rotating shaft portion and the rotating shaft portion is rotated by the tightening rotational torque applying shaft portion. An eccentric ring that rotates about a central axis of the outer peripheral surface in a direction opposite to a rotation direction of the rotation shaft portion, and the eccentricity when the rotation shaft portion is rotated by the tightening rotation torque applying shaft portion. A lateral load parallel to the bolt seating surface is applied to the bolt head via the rotating shaft portion by a ring, and the center axis line of the outer peripheral surface in the direction opposite to the rotating direction of the rotating shaft portion is applied. The bolt head and the bolt An eccentric movement mechanism unit that brings about movement of the part, the tightening rotation torque applying shaft part has a first engagement part, and the rotation shaft part engages with the first engagement part. The first engagement portion and the second engagement portion are engaged so that the rotation shaft portion transmits the rotational torque applied by the tightening rotation torque application shaft portion to the bolt head. And a bolt tightening unit that is engaged with a play that allows a predetermined amount of relative movement parallel to the bolt seat surface of the rotating shaft part with respect to the tightening rotational torque applying shaft part. An apparatus is provided.

  That is, according to the first aspect of the present invention, the tightening rotation torque applying shaft portion that is connected to the rotational power source and applies the rotating torque for rotating the male screw portion, and the rotation torque applied by the tightening rotation torque applying shaft portion is the bolt. In order to transmit to the head and rotate the male screw part, the lateral load parallel to the bolt seating surface is bolted to intentionally slide the screw surface and bolt seating surface in a direction perpendicular to the bolt axis. When the bolt tightening device has a lateral load applying means to be applied to the head, the screw surface and the bolt seat surface are slightly slid in the direction perpendicular to the bolt axis when the object to be fastened is tightened using the bolt. Thus, it is possible to tighten the bolt by applying a rotational torque for rotating the male screw portion of the bolt to the bolt head. Here, the screw surface indicates a surface on which a male screw portion of a bolt and a female screw corresponding to the male screw portion are engaged. The bolt seat surface indicates a surface where the fastened body and the bolt head are engaged, and when a washer such as a flat washer or a spring washer is disposed between the bolt head and the fastened body. Indicates a surface on which the washer and the fastened body are engaged.

  According to the lateral load applying means of the invention described in claim 1, when the bolt is tightened by the eccentric ring of the eccentric movement mechanism portion, the surface pressure of the screw surface and the bolt seat surface is intentionally biased. In this state, the bolt can be tightened with the bolt head sliding in parallel with the bolt seat surface. It is known that when the object plane slides linearly with a translational force, the apparent friction coefficient in the rotational direction of the object when a rotational force is added is very small. That is, when the object is sliding straight, the object can be rotated with a smaller rotational torque than when the object is rotated while the object is stationary. Therefore, according to the invention of claim 1, which enables the bolt to be tightened in a state where the bolt head slides parallel to the bolt seat surface, it is necessary when tightening the bolt. The tightening rotational torque can be further reduced compared to the case where the bolt is tightened in a state where the bolt head does not slide parallel to the bolt seat surface, and the bolt brought about when the bolt is tightened. It becomes possible to increase the axial force.

  Furthermore, according to the lateral load applying means of the invention described in claim 1, when the rotational torque is applied to the rotating shaft part to tighten the bolt and the rotating shaft part is rotated in the bolt tightening direction, it is rotated by the eccentric ring. A lateral load parallel to the bolt seat surface is applied to the bolt head through the shaft portion, and the bolt head around the central axis of the outer peripheral surface of the eccentric ring in the direction opposite to the rotation direction of the rotating shaft portion By having an eccentric movement mechanism that moves the bolt shaft, the bolt head and bolt shaft move around the central axis of the outer peripheral surface of the eccentric ring in the direction opposite to the bolt tightening direction when tightening the bolt. While rotating, the bolt can be tightened by rotating the rotation shaft portion around the rotation center axis in the bolt tightening direction.

  Applying a lateral load parallel to the bolt seat surface to the bolt head via the rotating shaft by the eccentric ring results in a high surface pressure part on a part of the screw surface, and in the direction opposite to the bolt tightening direction. The movement of the bolt shaft portion around the central axis of the outer peripheral surface of the eccentric ring causes a rotational movement of the high surface pressure portion in a direction opposite to the bolt tightening direction. The movement of the high surface pressure portion generated on the threaded surface is caused by placing the inner ring in the outer ring and bringing the inner ring into contact with the outer ring so that the inner ring does not slip. In this case, the inner ring is given a rotational force in the bolt tightening direction around its own rotational axis. That is, by rotating the bolt shaft around the central axis of the outer peripheral surface of the eccentric ring in the direction opposite to the bolt tightening direction, rotation in the bolt tightening direction around its own rotation axis with respect to the bolt shaft Force can be applied, and the tightening rotational torque required when tightening the bolt can be further reduced, and the bolt axial force generated when tightening the bolt can be increased more effectively. It becomes possible to plan.

  According to a second aspect of the present invention, the first engaging portion of the tightening rotational torque applying shaft portion is formed as a projection portion, and the second engaging portion of the rotating shaft portion is formed as a hole portion. A bolt fastening device according to claim 1 is provided.

  According to a third aspect of the present invention, the inner peripheral surface of the eccentric ring is disposed around the rotary shaft portion via a bearing. A bolt tightening device is provided.

  According to a fourth aspect of the present invention, the eccentric ring forms the outer peripheral surface so that a distance between the central axis of the outer peripheral surface of the eccentric ring and the central axis of the inner peripheral surface can be adjusted. The outer eccentric ring and the inner eccentric ring forming the inner peripheral surface, and the outer eccentric ring and the inner eccentric ring when the rotating shaft portion is rotated by the tightening rotational torque applying shaft portion. 4. The bolt tightening device according to claim 3, wherein the rings are engaged so as not to slide relative to each other.

  According to the invention described in each claim, when fastening the body to be fastened using a bolt, a lateral load parallel to the bolt seat surface is applied to the bolt head so that the surface pressure of the screw surface and the bolt seat surface is increased. A bolt tightening device that tightens the bolt by applying a rotational torque that rotates the male screw portion of the bolt to the bolt head in a biased state, and the tightening rotational torque applied when tightening the bolt is more effective. The common effect of realizing the provision of the bolt fastening device that can be reduced to the above is achieved.

It is a figure which shows one state of the volt | bolt before the lateral load parallel to a bolt seat surface is provided to a volt | bolt head. It is a figure which shows the state of a volt | bolt when the lateral load parallel to a bolt seat surface is provided to a volt | bolt head from the state shown by FIG. 1, and also the rotational torque which rotates a volt | bolt head to a socket is provided. . It is a figure explaining the structure of one Embodiment of the bolt fastening apparatus of this invention. It is a figure which shows one Embodiment of an eccentric ring.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
First, the basic concept of the bolt fastening method using the bolt fastening device of the present invention will be described with reference to FIGS. 1 and 2.

  FIG. 1 is a diagram illustrating a state of a bolt before a lateral load parallel to the bolt seat surface is applied to the bolt head. In FIG. 1, 1 is a bolt, 2 is a bolt head, 3 is a bolt shaft portion, 4 is a male screw portion provided on the bolt shaft portion 3, 5 is each fastened part, and 6 is engaged with a male screw portion. A female screw portion, 7 is a socket for transmitting a rotational torque to the bolt head 2, 8 is a bolt seat surface on which the bolt head 2 and the component to be fastened 5 are engaged, and 9 is a male screw portion 4 and a female screw. Thread surfaces 10 serving as surfaces with which the portion 6 engages are shown as friction joint surfaces between the parts to be fastened.

  FIG. 2 shows a state in which a lateral load parallel to the bolt seating surface 8 is applied to the bolt head 2 from the state shown in FIG. 1, and further, a rotational torque that rotates the bolt head 2 is applied to the socket 7. It is a figure which shows the state of a volt | bolt.

  As shown in FIG. 2, when a lateral load parallel to the bolt seat surface 8 is applied to the bolt head 2 via the socket 7, the bolt axis 11 is inclined with respect to the normal 12 of the bolt seat surface, and The bolt head 2 is inclined with respect to the bolt seat surface 8. However, in FIG. 2, these inclinations are illustrated to clarify the state, but in reality, the angle θ <b> 1 of these inclinations is a very slight angle such as 0.01 °. .

  In such a state, that is, in a state where the bolt axis 11 is inclined with respect to the normal 12 of the bolt seat surface and the bolt head 2 is inclined with respect to the bolt seat surface 8, the rotational torque is transmitted via the socket 7. Is applied to the bolt head 2, the bolt is tightened in a state where the surface pressures of the bolt seat surface 8 and the screw surface 9 are biased.

  The present applicant applies a lateral load parallel to the bolt seat surface 8 to the bolt head 2, and biases the surface pressure of the bolt seat surface 8 and the screw surface 9 brought about when the bolt 1 is tightened. By tightening the bolt 1, the actual rotation center line of the bolt (also referred to as the instantaneous rotation center line) is caused from the bolt axis 11 to the screw surface 9 due to the uneven surface pressure of the bolt seat surface 8 and the screw surface 9. As a result, the bolt seat surface 8 can be moved in the higher surface pressure side direction, and thereby, a higher bolt axial force can be obtained with a smaller tightening torque than when a lateral load is not applied to the bolt head 2. It was found by finite element analysis (FEM) that this is possible.

  In order to derive this, the applicant firstly conducted a finite element method analysis to verify the behavior of the rotational torque required for tightening the bolt when a shear-type load is applied to the part to be fastened with the bolt. It went by.

  It is known that when a shear-type load is applied to a body to be fastened with a bolt, a phenomenon that the bolt easily rotates, that is, a loosening of the bolt may occur. There is a theory that this phenomenon is caused by a decrease in the friction coefficient in the rotational direction around the bolt axis. According to this theory, when there is a side slip on both the screw surface and the bolt seat surface, the friction coefficient in the rotational direction around the bolt axis decreases to an extremely small value such as 0.005 to 0.02, He explains that it will cause the bolt to rotate loosely.

  The applicant of the present invention is an analysis model corresponding to a case where a shear-type load is applied to a body to be fastened with a bolt and a case where a shearing load is not applied, and the friction coefficient of the bolt seat surface and the screw surface is 0. Form an analysis model with a constraint condition that maintains the actual friction coefficient inherent to the bolt bearing surface and screw surface, for example, about 0.1, rather than an extremely small value of 0.005 to 0.02. And this theory was verified.

  As a result, in the state where the surface pressure of the bolt seat surface and screw seat surface is biased due to the application of the shear load to the fastened body, the friction coefficient of the bolt seat surface and screw surface is the original friction. In spite of being maintained as a coefficient, that is, even if the friction coefficient of the bolt seat surface and the screw surface is not set to an extremely small value of 0.005 to 0.02, the rotation center line of the bolt is changed from the bolt axis to the high pressure surface portion It has been found that the torque required to rotate the bolt is reduced by moving in the direction toward the side as compared with the case where the shear-type load is not applied to the fastened body.

  From this, the present applicant, the phenomenon that the bolt easily rotates in a state where a shear-type load is applied to the body to be fastened with the bolt, is because the friction coefficient in the rotational direction around the bolt axis is reduced. This is caused by the uneven surface pressure of the bolt seat surface and screw surface due to the application of the shear type load, and the actual rotation of the bolt due to the uneven surface pressure of the bolt seat surface and screw surface. The basic concept that the center line moves from the bolt axis in the direction approaching the bolt bearing surface and the high surface pressure portion of the screw surface, thereby reducing the torque required to rotate the bolt.

  The actual rotation center line of the bolt caused by the uneven surface pressure of the bolt seat surface and the screw surface is ideally a straight line connecting the high surface pressure portion of the bolt seat surface and the high surface pressure portion of the screw surface. It is possible. This is because it is appropriate to consider that the portion having a high surface pressure is difficult to move and that the high surface pressure portion is rotated about the rotation center. However, it is unlikely that the unevenness of the surface pressure of the bolt seat surface and the screw surface is brought about at a single point, and is generally brought about with a distribution over a certain area. Therefore, the actual rotation center line of the bolt caused by the bias of the surface pressure of the bolt seat surface and the screw surface connects the portion close to the high surface pressure portion of the bolt seat surface and the portion close to the high pressure surface portion of the screw surface. We think that it is appropriate to infer that it will be a straight line.

  Further, the actual rotation center line of the bolt caused by the uneven surface pressure of the bolt seat surface and the screw surface connects the portion close to the high surface pressure portion of the bolt seat surface and the portion close to the high surface pressure portion of the screw surface. By considering it as a straight line, the actual rotation center line of the bolt moves from the bolt axis in a direction approaching the high contact pressure portion, and the shortest distance from the actual rotation center line of the bolt to the high contact pressure portion is shortened. Thus, it is possible to easily explain the phenomenon that the rotational torque necessary to rotate the bolt is reduced. If it is considered that the actual bolt rotation center line moves away from the high contact pressure part, the shortest distance from the bolt rotation center axis to the high contact pressure part becomes long, and it is necessary to rotate the bolt. Torque will increase and will not match the analysis results.

  Next, for the purpose of increasing the bolt axial force at the time of bolt tightening, the present applicant intends to verify whether or not this basic concept can be applied to the bolt tightening method. The finite element method analysis shows the behavior of the surface pressure of the bolt seat surface 8 and the screw surface 9 and the rotational torque required to rotate the bolt 1 in a state where a lateral load parallel to the bolt seat surface 8 is applied to the part 2. Verification was performed.

  In this verification, an analysis model corresponding to the case where a lateral load parallel to the bolt seat surface 8 is applied to the bolt head 2 and the case where it is not applied, the friction coefficient of the bolt seat surface 8 and the screw surface 9 is as follows. The value is not an extremely small value such as 0.005 to 0.02, but a constraint condition that maintains a realistic friction coefficient inherent to the bolt seat surface 8 and the screw surface 9, for example, about 0.1 friction coefficient, is used. An attached analytical model was formed and verified.

  As a result, in the same manner as when a shear-type load is applied to the body to be fastened with bolts, a lateral load is applied to the bolt head 2 to bias the surface pressure of the bolt seat surface 8 and the screw seat surface 9. In this state, although the friction coefficient of the bolt seat surface 8 and the screw surface 9 is maintained as the original friction coefficient, that is, the friction coefficient of the bolt seat surface 8 and the screw surface 9 is 0. Even if it is not set to a very small value such as 0.005 to 0.02, it is compared with the case where a lateral load is not applied to the bolt head 2 by moving the rotation center line of the bolt from the bolt axis 11 toward the high pressure surface side. Thus, it has been found that the torque required to rotate the bolt 1 decreases.

  Therefore, it is possible to apply this basic concept to the bolt tightening method, and apply a lateral load parallel to the bolt seat surface 8 to the bolt head 2 to bring about the bolt seat surface 8 brought about when the bolt 1 is tightened. Further, by tightening the bolt 1 with the surface pressure of the screw surface 9 biased, the actual rotation center line of the bolt is increased from the bolt axis 11 by the bias of the surface pressure of the bolt seat surface 8 and the screw surface 9. It can be moved to the surface pressure side direction, and it is considered that it is verified that it is possible to tighten the bolt with a smaller tightening rotational torque than when no lateral load is applied to the bolt head 2. .

  As described above, according to the bolt tightening method by the bolt tightening device of the present invention, the friction coefficient itself is not changed, but the tightening method is changed, specifically, the bolt seat surface 8 and the screw surface 9 are changed. By tightening the bolt in a state where the surface pressure is biased, the same effect as that obtained by reducing the friction coefficient of the screw surface 9 is obtained. That is, the bolt axial force when the bolt 1 is tightened is increased. There is an effect to be realized.

  In addition, after the tightening of the bolt 1 is completed and the tightening rotational torque applied to the bolt head 2 is released, the male screw portion and the female screw are caused by the frictional force generated according to the friction coefficient of the screw surface 9 itself. The engagement with the part can be maintained.

  As a result, there is no restriction on increasing the axial force due to the self-supporting of the screw, which is a problem when only the friction coefficient is reduced in order to increase the axial force of the bolt axial force. It is possible to provide a high bolt axial force.

  The higher bolt axial force brings about a strong friction bonding on the frictional engagement surface 10 between the respective fastened parts, and the strong frictional joint allows the sliding between the fastened parts when a shear external force is applied. Thus, it is possible to prevent the slippage between the parts to be fastened and prevent the screw from loosening more completely.

  In the bolt tightening method using the bolt tightening device of the present invention, there is a possibility that a very small gap may remain between the bolt head 2 and the bolt seat surface 8 when the bolt tightening is completed. There is. However, the gap remaining when the bolt tightening is completed is such that the bolt itself balances when the rotational torque applied to the bolt head 2 is released or when a shearing external force is applied to the component to be fastened. Except for adaptation to fastening parts where rotational torque frequently acts on the bolts, such as the hinge part of the glasses, for example. The effect of the gap is considered negligible.

  Further, in the bolt tightening method by the bolt tightening device of the present invention, when the bolt is tightened, the male screw portion is inserted with an inclination with respect to the corresponding female screw portion, depending on the degree of the inclination. Screw biting can be a problem. In that case, it is possible to reduce screw engagement by applying a friction coefficient stabilizer to the screw surface within a range where self-supporting of the screw after bolt tightening does not become a problem.

Next, an embodiment of the bolt fastening device of the present invention will be described below.
FIG. 3 is a diagram illustrating the configuration of an embodiment of the bolt fastening device of the present invention.
In the figure, 21 is a bolt tightening device, 22 is a tightening rotational torque applying shaft portion, 23 is a lateral load applying means, 24 is a rotating shaft portion, 25 is an eccentric moving mechanism portion, 26 is an eccentric ring, and 27 is a housing. . In the figure, reference numerals 28, 29, 30 and 31 denote a first bevel gear, a second bevel gear, a third bevel gear and a fourth bevel gear, respectively, 32, 33, 34, 35 and 36. Indicates a first bearing, a second bearing, a third bearing, a fourth bearing, and a fifth bearing.

  In the embodiment shown in FIG. 3, a bolt fastening device of the present invention that can be applied to a hexagon head bolt is shown. However, the present invention is not limited to this, and the bolt fastening device 21 of the present invention can be of various types by changing the shape of the bolt engaging portion 40 of the rotating shaft portion 24 described later that engages with the bolt head. It can be applied to bolts.

  The tightening rotational torque applying shaft portion 22 is connected to the rotational power source 45 and plays a role of applying rotational torque for rotating the male screw portion of the bolt. The lateral load applying means 23 transmits the rotational torque applied by the tightening rotational torque applying shaft portion 22 to the bolt head, and when the male screw portion of the bolt is rotated by the rotational torque transmitted to the bolt head. In order to intentionally deviate the surface pressure of the screw surface and the bolt seat surface, the lateral force parallel to the bolt seat surface is imparted to the bolt head.

  When the bolt is tightened, the lateral load applying means 23 is rotated by the tightening rotational torque applying shaft portion 22 and rotated in the bolt tightening direction, and the rotational torque is transmitted to the bolt head to tighten the male screw portion of the bolt. It has the rotating shaft part 24 rotated in the direction. Further, the lateral load applying means 23 is an eccentric ring 26 having an outer peripheral surface 43 and an inner peripheral surface 44, wherein the central axis of the outer peripheral surface 43 and the central axis of the inner peripheral surface 44 are different. When the rotary shaft portion 24 is rotated by the tightening rotational torque applying shaft portion 22 around the center axis line of the outer peripheral surface 43 in a direction opposite to the rotation direction of the rotary shaft portion 24. When the rotating shaft portion 24 is rotated by the tightening rotational torque applying shaft portion 22, the lateral load parallel to the bolt seat surface is applied to the bolt head surface via the rotating shaft portion 24. And an eccentric moving mechanism portion 25 that is provided to the portion and causes the bolt head and the bolt shaft portion to move around the central axis of the outer peripheral surface 43 in the direction opposite to the rotation direction of the rotating shaft portion 24.

  In the embodiment of the bolt tightening device 21 of the present invention shown in FIG. 3, a rotational power source 45 such as a nut runner is attached to the upper end of the tightening rotational torque applying shaft portion 22, and the tightening rotational torque applying shaft is also provided. The vicinity of the upper end portion of the portion 22 is supported by the casing 46 via a first bearing 32 that is a component of the eccentric movement mechanism portion 25. The lower end portion of the tightening rotational torque applying shaft portion 22 is provided with a projection 41 serving as a first engagement portion, and the upper end portion of the rotation shaft portion 24 is engaged with the projection 41. The hole part 42 used as a part is provided. The protrusion 41 and the hole 42 are engaged so that the rotation shaft 24 transmits the rotation torque applied by the tightening rotation torque applying shaft 22 to the bolt head, and the tightening rotation torque applying shaft 22. Is engaged with a play (gap) that allows a predetermined amount of relative movement parallel to the bolt seat surface of the rotary shaft portion 24. The engagement form of the tightening rotational torque applying shaft portion 22 and the rotating shaft portion 24 is not limited to this, and for example, a hole is provided at the lower end portion of the tightening rotational torque applying shaft portion 22 and the rotating shaft The upper end portion of the portion 24 may be provided with a protrusion that engages with the hole.

  Further, in the embodiment of the bolt fastening device 21 of the present invention shown in FIG. 3, the eccentric moving mechanism 25 of the lateral load applying means 23 includes the eccentric ring 26 and the rotating shaft 24 is tightened and the rotational torque applying shaft is provided. The first bevel gear 28 and the second bevel gear 29 are components that bring the eccentric ring 26 to rotate around the central axis of the outer peripheral surface 43 in the direction opposite to the rotation direction of the rotation shaft portion 24 when being rotated by the rotation shaft 22. , A third bevel gear 30, a fourth bevel gear 31, and a housing 27. Furthermore, the eccentric movement mechanism unit 25 includes a first bearing 32, a second bearing 33, a third bearing 34, a fourth bearing 35, a first shaft 37, and a second shaft as components that enable rotation of these bevel gears. And a shaft 38.

  The first bevel gear 28 is attached to the tightening rotational torque applying shaft portion 22 by, for example, press fitting so that the first bevel gear 28 can be rotated in the rotation direction of the tightening rotational torque applying shaft portion 22 together with the rotation of the tightening rotational torque applying shaft portion 22. It is fixed against. The first bevel gear 28 and the second bevel gear 29 are meshed with each other, and the second bevel gear 29 is disposed so as to be rotated with respect to the casing 46 via the second bearing 33 together with the first shaft 37. . Further, the first bevel gear 28 and the third bevel gear 30 are engaged with each other, and the third bevel gear 30 is disposed so as to be rotated with respect to the casing 46 via the third bearing 34 together with the second shaft 38. Is done.

  The fourth bevel gear 31 is meshed with each of the second bevel gear 29 and the third bevel gear 30, and the rotational force from the second bevel gear 29 and the third bevel gear 30 is transmitted to the first bevel gear 28. Arranged to provide rotation in a direction opposite to the direction of rotation. The housing 27 is fixed to the fourth bevel gear 31 by, for example, press fitting so that the housing 27 can be rotated together with the rotation of the fourth bevel gear 31 in the rotation direction of the fourth bevel gear 31.

  The eccentric ring 26 is attached to the lower end portion of the housing 27 by, for example, press fitting so that the eccentric ring 26 can be rotated in the rotation direction of the housing 27 together with the rotation of the housing 27. The inner peripheral surface 44 of the eccentric ring 26 is disposed around the rotary shaft portion 24 via the fifth bearing 36. In the present embodiment, the inner peripheral surface 44 of the eccentric ring 26 is interposed via the fifth bearing 36 so that the smooth rotation of the rotating shaft portion 24 and the eccentric ring 26 in different rotational directions is not hindered. However, it is possible to smoothly rotate each of the rotating shaft portion 24 and the eccentric ring 26 in different rotation directions by applying a lubricant or the like without using the fifth bearing 36, for example. In such a case, the fifth bearing 36 may be excluded from the configuration.

  FIG. 4 is a view showing an embodiment of the eccentric ring. In the embodiment shown in FIG. 3, an eccentric ring 26 formed from one piece is shown. However, the form of the eccentric ring is not limited to this. For example, as shown in FIG. 4, the distance between the central axis of the outer peripheral surface 53 of the eccentric ring 50 and the central axis of the inner peripheral surface 54 can be adjusted. The outer eccentric ring 51 that forms the outer peripheral surface 53 and the inner eccentric ring 52 that forms the inner peripheral surface 54, and the outer eccentric ring when the rotary shaft portion 24 is rotated by the tightening rotational torque applying shaft portion 22. The eccentric ring may be configured such that 51 and the inner eccentric ring 52 are engaged so as not to slide relative to each other.

Below, operation | movement of the bolt fastening apparatus of embodiment shown by FIG. 3 is demonstrated.
First, as a setting operation for starting the operation of tightening the bolt, the casing 46 is disposed so that the eccentric ring 26 is parallel to the bolt seat surface, and the bolt engaging portion 40 and the bolt head of the rotating shaft portion 24 are arranged. The part is engaged. When such setting is completed, the tightening rotation torque applying shaft portion 22 is then rotated in the bolt tightening direction, and the rotation shaft portion 24 is rotated in the bolt tightening direction together with the rotation, and the bolt head portion is rotated. Rotational torque is transmitted and the male screw part is rotated in the bolt tightening direction.

  On the other hand, when the tightening rotation torque applying shaft portion 22 is rotated in the bolt tightening direction to tighten the bolt, the first bevel gear 28 is rotated in the bolt tightening direction together with the rotation. The rotation of the first bevel gear 28 is transmitted to the fourth bevel gear 31 via the second bevel gear 29 and the third bevel gear 30, and the fourth bevel gear 29 and the third bevel gear 30 act on the fourth bevel gear 31. The gear 31 is rotated in a direction opposite to the rotation direction of the first bevel gear 28, that is, rotated in a direction opposite to the bolt fastening direction. The housing 27 is rotated together with the rotation of the fourth bevel gear 31, and the eccentric ring 26 is rotated together with the rotation of the housing 27, that is, the fourth bevel gear 31 is rotated. The eccentric ring 26 is rotated in the direction opposite to the bolt tightening direction in accordance with the rotation. Since the rotation of the eccentric ring is caused by the housing 27 and the outer peripheral surface 43 of the eccentric ring 26 being fixed, the eccentric ring 26 is rotated around the central axis of the outer surface 43 of the eccentric ring 26. Therefore, the bolt is rotated in the direction opposite to the bolt tightening direction.

  Since the central axis of the outer peripheral surface 43 of the eccentric ring 26 and the central axis of the inner peripheral surface 44 are different, when the eccentric ring 26 is rotated around the central axis of the outer surface 43, the inner peripheral surface 44 has its own center. Rather than a rotation around the axis, a movement around the central axis of the outer surface 43, a so-called eccentric movement, is brought about. The eccentric movement of the inner peripheral surface 44 of the eccentric ring 26 causes the same eccentric movement to the rotary shaft portion 24 disposed via the fifth bearing 36 inside the inner peripheral surface 44 of the eccentric ring 26. Can do. The eccentric ring 26 is disposed in parallel with the bolt seat surface in the initial setting, and the rotary shaft portion 24 and the bolt head portion are engaged with each other. The rotary shaft portion 24 is a tightening rotational torque applying shaft portion. 22 is engaged with a play (gap) that allows a predetermined amount of relative movement parallel to the bolt seat surface, so that the casing 46 is moved relative to the bolt seat surface by the eccentric movement of the rotary shaft portion 24. It does not move relatively, and by the eccentric movement of the rotating shaft 24, a lateral load parallel to the bolt seat surface can be applied to the bolt head, and when fastening the fastened body using the bolt, In a state where the surface pressures of the screw surface and the bolt seat surface are biased, it is possible to apply a rotational torque for rotating the male screw portion of the bolt to the bolt head and tighten the bolt. Note that, for example, a reaction force receiving portion that prevents relative movement of the casing 46 with respect to the bolt seat surface may be provided depending on, for example, the weight of the bolt fastening device itself.

  Further, the movement of the inner peripheral surface 44 around the central axis of the outer surface 43 of the eccentric ring 26 can be continued while the tightening rotational torque applying shaft portion 22 is rotated, that is, while the bolt is tightened. When tightening the bolt, make sure that the surface pressure of the screw surface and the bolt seat surface is intentionally biased and that the bolt head slides parallel to the bolt seat surface. It is possible to tighten. It is known that when the object plane slides linearly with a translational force, the apparent friction coefficient in the rotational direction of the object when a rotational force is added is very small. That is, when the object is sliding straight, the object can be rotated with a smaller rotational torque than when the object is rotated while the object is stationary. Therefore, according to the present bolt tightening device that enables the bolt to be tightened while the bolt head slides parallel to the bolt seating surface, the tightening rotational torque required for tightening the bolt Compared to the case where the bolt is tightened in a state where the bolt head does not slide parallel to the bolt seating surface, the bolt axial force generated when the bolt is tightened can be reduced. High axial force can be achieved.

  Further, since the eccentric ring 26 is rotated in a direction opposite to the rotation direction of the rotary shaft portion 24, when the rotary shaft portion 24 is rotated in the bolt tightening direction and the bolt is tightened, the eccentric ring 26 is rotated in the bolt tightening direction. The bolt head and the bolt shaft can be moved around the central axis of the outer peripheral surface 43 of the eccentric ring 26 in the direction opposite to the bolt tightening direction. Therefore, when the bolt is tightened, the bolt head and the bolt shaft are moved around the central axis of the outer peripheral surface 43 of the eccentric ring 26 in the direction opposite to the bolt tightening direction, and the rotating shaft 24 is rotated at its center of rotation. The bolt can be tightened by rotating in the bolt tightening direction around the axis.

  Application of a lateral load parallel to the bolt seat surface to the bolt head via the rotating shaft portion 24 by the eccentric ring 26 results in a high-pressure surface portion in a part of the screw surface, and in a direction opposite to the bolt tightening direction. The movement of the bolt shaft portion around the central axis of the outer peripheral surface 43 of the eccentric ring 26 causes the rotational movement of the high-pressure surface portion in the direction opposite to the bolt tightening direction. The movement of the high-pressure surface that occurs on the threaded surface is caused by placing the inner ring in the outer ring and bringing the inner ring into contact with the outer ring so that the inner ring does not slip. This is the same as the movement of the high-pressure surface that is caused when moving around the axis. In such a case, the inner ring is given a rotational force in the bolt tightening direction around its own rotational axis. That is, by causing the bolt shaft portion to move around the central axis of the outer peripheral surface 43 of the eccentric ring 26 in the direction opposite to the bolt tightening direction, the bolt shaft portion moves toward the bolt tightening direction about its own rotation axis. The rotational torque required for tightening the bolts can be further reduced, and the tightening rotational torque required for tightening the bolts can be further reduced. Can be achieved.

DESCRIPTION OF SYMBOLS 1 Bolt 2 Bolt head 8 Bolt seat surface 21 Bolt clamping apparatus 22 Tightening rotational torque provision shaft part 23 Lateral load provision means 24 Rotation shaft part 25 Eccentric movement mechanism part 26 Eccentric ring

Claims (4)

In the bolt tightening device used when fastening the body to be fastened, using a bolt having a bolt head and a bolt shaft portion having a male screw portion,
A tightening rotational torque applying shaft portion that is connected to a rotational power source and applies a rotational torque that rotates the male screw portion;
When the rotational torque applied by the tightening rotational torque applying shaft portion is transmitted to the bolt head, and the male screw portion is rotated by the rotational torque transmitted to the bolt head, the screw surface and the bolt seat A lateral load applying means for applying a lateral load parallel to the bolt seat surface to the bolt head in order to intentionally bias the surface pressure provided to the surface;
The lateral load applying means is
When the bolt is tightened, a rotation torque is applied by the tightening rotation torque applying shaft portion and rotates in the bolt tightening direction, and the rotation torque is transmitted to the bolt head to rotate the male screw portion in the bolt tightening direction. And
An eccentric ring having an outer peripheral surface and an inner peripheral surface, the central axis of the outer peripheral surface being different from the central axis of the inner peripheral surface, wherein the inner peripheral surface is disposed around the rotating shaft portion and the rotation An eccentric ring that rotates about a central axis of the outer peripheral surface in a direction opposite to a rotation direction of the rotation shaft portion when the shaft portion is rotated by the tightening rotation torque applying shaft portion, and the rotation shaft portion is When rotating by the tightening rotational torque application shaft portion, the eccentric ring applies a lateral load parallel to the bolt seat surface to the bolt head via the rotation shaft portion, and the rotation shaft portion rotates. An eccentric moving mechanism that provides movement of the bolt head and the bolt shaft around the central axis of the outer peripheral surface in a direction opposite to the direction;
The tightening rotation torque applying shaft portion has a first engagement portion, the rotation shaft portion has a second engagement portion that engages with the first engagement portion, and the first engagement portion and the first engagement portion. The two engaging portions are engaged so that the rotating shaft portion transmits the rotating torque applied by the tightening rotating torque applying shaft portion to the bolt head, and the tightening rotating torque applying shaft portion is Engaged with a play that allows a predetermined amount of relative movement parallel to the bolt seat surface of the rotating shaft,
Bolt tightening device characterized by that.   2. The bolt according to claim 1, wherein the first engaging portion of the tightening rotational torque applying shaft portion is formed as a protrusion, and the second engaging portion of the rotating shaft portion is formed as a hole portion. Tightening device.   The bolt tightening device according to claim 1 or 2, wherein an inner peripheral surface of the eccentric ring is disposed around the rotary shaft portion via a bearing. The eccentric ring forms the inner peripheral surface with the outer eccentric ring that forms the outer peripheral surface so that the distance between the central axis of the outer peripheral surface of the eccentric ring and the central axis of the inner peripheral surface can be adjusted. And an inner eccentric ring
The outer eccentric ring and the inner eccentric ring are engaged with each other so as not to slide relative to each other when the rotating shaft portion is rotated by the tightening rotational torque applying shaft portion. The bolt fastening device according to claim 3.

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