JP6286374B2 - Washer - Google Patents

Description

  The present invention relates to a washer disposed between a fastening member that is fastened by rotation with a fastening tool and a fastened member.

  When a high-torque screwing is performed using a fastening tool such as an electric torque control wrench, a claw that is integrally fixed to the fastening tool to prevent the reaction force related to the screwing from being transmitted to the operator There is known a method in which a screw is provided in a state in which a part is provided and the claw part is in contact (or engaged) with a part (or all) of an adjacent fastening member such as a bolt or nut. In this method, since the nail | claw part of a fastening tool is supported by the said nut etc. which were already fastened, since the motion of the rotation direction of a fastening tool is blocked | prevented, the reaction force from the fastening tool which concerns on screwing is an operator. Is not transmitted to.

  In addition, when the screwing as described above is performed, it is also an important factor to prevent the washer from rotating together. A method for roughening the surface of a fastening member or a fastened member by shot blasting is known for preventing the washer from rotating together. Further, Patent Documents 1 and 2 disclose another method in which a washer is provided with unevenness on one side or both sides of a washer so that the convex portion is crushed when the tightening progresses and the fastening is nearly completed. Further, in Patent Document 3, a screwing protrusion (a biting protrusion in Patent Document 1) is provided on the back surface of a screw such as a washer so that the screw such as a washer can be prevented from loosening. A stop structure is disclosed.

Japanese Patent No. 4717055 JP 2003-172332 A Japanese Patent No. 3474341

  The method of providing the above-mentioned claw part has the subject that it cannot apply, when the member for latching claw parts, such as an adjacent fastened nut, is not near the screwing location. Further, the method of performing the shot blasting has a problem that it cannot be applied when the member to be fastened is a material having high hardness (for example, steel material having high hardness such as SCM material). Further, after the tightening related to the screwing is finished, it is desirable that the contact surface between the washer and the member to be fastened has high adhesion, but there is a problem that the adhesion after the tightening may be deteriorated. .

  While the washer or the locking structure described in Patent Documents 1 to 3 is configured to prevent co-rotation and loosening of the screws, it is not configured to receive the reaction force of the fastening tool. When the reaction force is transmitted to the operator and high torque is tightened, it is not easy for the user to support the reaction force.

  The present invention has been made to solve the above-described problem, and its main purpose is to receive the reaction force so that the reaction force related to the fastening between the fastening member and the fastened member is not transmitted to the operator. It is possible to provide a washer that is configured to be capable of preventing the rotation of the washer more reliably.

  The washer according to the present invention is provided with an engaging portion that engages with the outer case on the outer peripheral portion, and the contact surface with the member to be fastened bites into the member to be fastened when tightened by a fastening tool. The biting protrusion which has the press-contact part press-contacted with is protrudingly provided.

  That is, in the first aspect of the present invention, the washer is disposed between a fastening member to be fastened by a fastening tool and a fastened member, and the fastening tool is integrally fixed to the tool body. And an inner case that is rotatably supported in the outer case and that rotates and fastens the fastening member. In the washer, an outer peripheral portion has an engaging portion that engages with the outer case. The contact surface with the to-be-fastened member is provided with a projecting protrusion having a press-contact portion that bites into the to-be-fastened member and press-contacts with the to-be-fastened member when tightened by the fastening tool.

  According to this aspect, when tightening with the fastening tool, the biting projection of the washer bites into the fastened member due to the axial force applied in the thickness direction of the washer, and the biting projection is fastened through the pressure contact portion. It comes to be pressed against. For this reason, even when a reaction force is applied to the washer at the time of the tightening, the washer can apply the reaction force via the pressure contact portion by engaging the engaging part of the outer case and the washer at the time of the tightening. The reaction force can be received and released to the fastened member side. That is, the washer according to the present disclosure can prevent the reaction force related to the fastening between the fastening member and the fastened member from being transmitted to the operator.

  Furthermore, since the biting protrusion bites into the fastened member when tightening with the fastening tool, it is possible to more reliably prevent the washer from rotating together. As a result, the torque coefficient value can be set within a predetermined variation range obtained by a tightening test or the like. For example, the yield strength of the joint in the frictional joining of the high-strength bolt can be managed more accurately.

  The second aspect of the present invention is a fastening structure in which a screw shaft of a bolt is inserted into a screw insertion hole provided in each of a plurality of members to be fastened, and a nut is screwed to the tip of the screw shaft via a washer. The bolt and the nut include an outer case that engages with the nut and an inner case that is rotatably supported in the outer case and rotates and tightens the screw shaft of the bolt. A bite that is fastened by a tool and has a pressure contact portion that is brought into contact with the fastened member and is fastened to the fastened member by the contact surface of the washer with the fastened member when fastened by the fastening tool. A protrusion is provided.

  According to a third aspect of the present invention, in the fastening structure according to the second aspect, the screw shaft of the bolt is provided with a fragile portion that breaks when a torque of a predetermined level or more is applied to the engagement portion. It is characterized by that.

  The washer according to the fourth aspect of the present invention is used in the fastening structure described in the second or third aspect.

  According to the second aspect (fourth aspect), when the fastening tool rotates the inner case (screw shaft of the bolt) when tightening with the fastening tool, the bolt and the nut are fastened, and the nut and the fastened member The washer disposed between the two receives an axial force in the thickness direction. Thereby, the biting protrusion of the washer bites into the fastened member, and the biting protrusion is pressed into contact with the fastened member via the press contact portion. In this fastening process, the nut rotates in the reverse direction as the outer case receives the reaction force accompanying the rotation of the inner case and rotates in the reverse direction. That is, the screw shaft of the bolt and the nut can be relatively rotated by the rotational force and reaction force of the fastening tool, so that the reaction force related to tightening can be prevented from being transmitted to the operator.

  At this time, in addition to the nut, a rotating force (reaction force) in the same direction as the nut is also applied to the washer, but the rotating force is received through the press-contact portion of the washer, so the washer does not rotate (turn). . As a result, the torque coefficient value can be set within a predetermined variation range obtained by a tightening test or the like. For example, the yield strength of the joint in the frictional joining of the high-strength bolt can be managed more accurately.

  According to the third aspect, for example, in the tightening process of the bolt and the nut, the fragile portion is broken when a torque of a predetermined level or more is applied to the engaging portion of the screw shaft of the bolt. It can be managed to be within a predetermined range.

  According to a fifth aspect of the present invention, in the washer according to the first or fourth aspect, the press-contact portion of the biting protrusion is on the front side in a direction in which the washer tries to rotate as the inner case rotates. An inclination angle of the surface of the pressure contact portion with respect to the contact surface is larger than an angle of inclination of the surface of the inclined portion continuous with the surface of the pressure contact portion and the apex of the biting protrusion with respect to the contact surface. Features.

  According to this aspect, since the inclination angle of the pressure contact portion surface with respect to the contact surface is set to be larger and steeper than the angle of the inclined surface with respect to the contact surface, more reliable biting of the biting protrusion is realized. The press-contact portion that bites into the fastened member is firmly pressed by the fastened member. In addition, since the surface of the inclined portion is gently inclined, even if the member to be fastened is a hard material, the biting protrusion can be firmly bitten into the member to be fastened without being crushed. Can do.

  According to a sixth aspect of the present invention, in the washer according to the first, fourth, or fifth aspect, the biting protrusion has a height of 0.2 mm or more from the contact surface.

  According to this aspect, since the biting protrusion is formed so as to have a height of 0.2 mm or more from the contact surface, the pressure contact portion of the biting protrusion and the fastened member can be contacted in a wider range. it can. That is, in the tightening process, a force for rotating the washer is more firmly received through the press contact portion, and the co-rotation of the washer can be more reliably prevented.

  According to a seventh aspect of the present invention, in the washer according to any one of the first aspect or the fourth to sixth aspects, the biting protrusion extends in a radial direction of the washer, and the washer It is provided in the site | part near the center of.

  According to this aspect, since the biting protrusion extending in the radial direction of the washer is provided at a portion near the center of the washer, even if the washer is warped in the manufacturing process or the tightening process, the biting protrusion is firmly fixed. And bite into the fastened member.

  In an eighth aspect of the present invention, in the washer according to any one of the first aspect or the fourth to seventh aspects, a projection group in which the biting protrusions are arranged in the circumferential direction is provided, and The protrusion groups are arranged at a predetermined angular pitch in the circumferential direction.

  According to this aspect, since the projection groups are arranged at a predetermined angular pitch, that is, the angular pitch between adjacent projection groups is constant, the force is applied to each projection group (each biting projection) in a balanced manner. In addition, the biting protrusion can be bitten into the fastened member more stably and reliably.

  According to the present invention, the biting protrusion of the washer is provided with a pressure contact portion that bites into the member to be fastened when being tightened by the fastening tool on the contact surface with the member to be fastened, and is pressed against the member to be fastened. Since the outer case of the fastening tool and the engaging part of the washer can be engaged, it is possible to prevent the reaction force related to the fastening between the fastening member and the fastened member from being transmitted to the operator. Furthermore, it is possible to prevent the washer from co-rotating more reliably, and to set the torque coefficient value within a predetermined variation range obtained by a tightening test or the like.

It is sectional drawing which shows the clamped state of the fastening structure which concerns on 1st Embodiment. It is the (a) top view and (b) bottom view of the washer concerning a 1st embodiment. It is the result of having measured the AA line surface of FIG. 2 with the tracer. It is a figure which cut | disconnects a washer along the AA line of FIG. 2, and shows the cross-sectional shape seen from the side surface. It is a top view which shows the modification of the washer which concerns on 1st Embodiment. It is a top view which shows the modification of the washer which concerns on embodiment. It is sectional drawing which shows the fastening state of the fastening structure which concerns on 2nd Embodiment. (A) is the perspective view which image | photographed the washer based on 2nd Embodiment from diagonally upward, (b) is the enlarged view to which the projection group periphery of the washer of (a) was expanded. It is the figure which showed the relationship between a torque, nut rotation angle, and axial force.

(Relationship between torque and axial force)
FIG. 9 is a diagram showing an example of the relationship between torque and nut rotation angle and axial force in friction welding of high-strength bolts. The left side of the drawing shows the relationship between torque and axial force, and the right side of the drawing shows the nut rotation angle. And the axial force.

  The relationship between torque T and axial force N related to torque method tightening is expressed by the following equation (1).

T = k × d × N (1)
Here, k is a torque coefficient and d is a bolt diameter.

  As shown in the equation (1), the function of the torque T and the axial force N is uniquely determined by the torque coefficient k. For example, in a high-strength bolt used for a building or a bridge, a bolt and a nut A torque coefficient k is defined as a standard for the set of washers. For example, as shown in FIG. 9, the torque coefficient value k is defined as a minimum value kmin or more and a maximum value kmax or less, and the tightening axial force N is within a predetermined range (Nmin or more and Nmax or less). The tightening torque TA is determined so as to enter.

  Here, the relationship of the formula (1) is established because the relationship between the slip coefficient μ1 between the nut 3 and the washer 1 and the slip coefficient μ2 between the washer 1 and the steel material 51 is expressed by the following formula (2 ) Is satisfied.

μ1 <μ2 Formula (2)
In general, the nut surface or the washer surface is lubricated on the nut side, or the steel material surface or the washer surface is shot blasted on the steel material side so as to satisfy the expression (2). However, when the relationship of the expression (2) is broken due to the influence of rain or the like and μ1> μ2, the torque coefficient k may be less than kmin (for example, k1 in FIG. 9). In this case, if tightening is performed with a tightening torque TA using a tightening tool or the like, an excessive axial force may be applied, and the bolt may be fully extended (see the broken line arrow in FIG. 9). On the other hand, if the torque TA is adjusted in anticipation of the change in the torque coefficient, the axial force N may be insufficient, and there is a problem that a stable axial force cannot be obtained. As a result, for example, it is impossible to sufficiently manage the proof strength of the joint in friction bonding of high-strength bolts. For this reason, countermeasures are necessary.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the invention, its scope of application, or its application.

-First embodiment-
FIG. 1 shows a tightening state of the fastening structure according to the present embodiment. Specifically, a state in which steel members 51 and 52 as fastened members are fastened using a washer 1 and bolts 2 and nuts 3 as fastening members is shown. A state in which a fastening tool 4 such as a torque control wrench is mounted is shown.

  The bolt 2 extends in the tightening direction, and has a screw shaft 21 provided with a thread 21a on the outer periphery, and an outer side in the radial direction at the end opposite to the tightening direction of the screw shaft 21 (lower side in FIG. 1). And a head portion 22 extending to the front.

  The steel materials 51 and 52 are, for example, plate-like chrome molybdenum steel materials (SCM materials), and screw insertion holes 51a and 52a for inserting the screw shaft 21 of the bolt 2 are formed in the steel materials 51 and 52, respectively. Yes.

  The fastening tool 4 is provided so as to cover a tool body 41 including a motor 45 and a shaft 44, an inner socket 42 whose one end side is open to be engageable with the nut 3, and an outer side of the inner socket 42. And a cylindrical outer case 43 that is fixedly mounted.

  The inner socket 42 has a bottomed cylindrical shape having a rotation axis along the axial direction of the screw shaft 21 of the bolt 2 inserted through the screw insertion holes 51 a, 52 a, 11. In the state facing the side (the lower side in FIG. 1), the central portion of the bottom is drivingly connected to the motor 45 via the shaft 44. And when fastening with the steel materials 51 and 52 using the volt | bolt 2 and the nut 3, the motor 45 is rotationally driven and the inner socket 42 is configured to rotate around the shaft 44 (rotation axis) with a predetermined torque. Has been.

  The outer case 43 has an opening 43a that is open on one end side so as to be engageable with an engaging portion 12 of a washer 1 described later. Specifically, for example, the opening 43 a of the outer case 43 is formed in a hexagonal shape so as to be slightly larger than the outer shape of the washer 1. When the bolt 2 and the nut 3 and the steel materials 51 and 52 are tightened by the fastening tool 4, when the nut 3 and the inner socket 42 are engaged, the engaging portion of the outer case 43 and the washer 1 described later is engaged. 12 is configured to be engaged.

(Composition of washer)
As shown in FIGS. 1 and 2, the washer 1 is formed of a hexagonal flat plate with a screw insertion hole 11 in the center, and the engaging portion 12 on the outer periphery of the washer 1 and the opening 43a of the outer case are engaged. It is configured to be compatible. Further, at the portion near the center of the contact surface 13 of the washer 1 on the steel material 51 side, there is a biting projection 14 extending in the radial direction of the washer 1 and protruding in the thickness direction of the washer 1 in the circumferential direction. Two are arranged side by side. The washer 1 is provided with three projection groups 15 formed of two biting projections 14 and 14 arranged in the circumferential direction at an angular pitch of 120 degrees spaced at equal angular intervals in the circumferential direction. The washer 1 is disposed between the nut 3 and the steel material 51.

  In addition, as shown in FIG. 5, the biting protrusion 14 may be provided in the site | part near the outer periphery in the contact surface 13 by the side of the steel material 51. FIG. However, by providing a biting protrusion 14 (protrusion group 15) at the center portion of the contact surface 13 of the washer 1, even if the washer 1 warps during the manufacturing process or tightening process, the portion near the center is The axial force of the bolt 2 by the nut 3 is directly received. Thereby, since the biting protrusion 14 bites into the steel material 51 firmly, it is more preferable to provide the biting protrusion 14 at a portion near the center of the contact surface 13.

In addition, although the protrusion group 15 shall consist of the biting protrusions 14 and 14 located in a line with the circumferential direction, it is not limited to this. For example, the projection group 15 may be configured by three or more biting projections 14 arranged in the circumferential direction. For example, the projection group 15 may be configured by one biting projection 14. In addition, although the three projection groups 15 are arranged at an angular pitch of 120 degrees in the circumferential direction, the present invention is not limited to this, and two or four or more projection groups 15 are arranged at a predetermined angular pitch. It may be arranged. However, if the number becomes too large (for example, a projection group is formed on the entire surface), the adhesion between the contact surface 13 of the washer 1 and the steel material 51 after the final tightening (tightening with standard bolt tension) is increased. It may not be secured sufficiently. Further, since the manufacturing cost increases as the number of the protrusion groups 15 increases, the number of the biting protrusions 14 constituting the protrusion group 15 is preferably about two or three, and the number of the protrusion groups 15 is The number is preferably about 2 to 4.

  The protrusion group 15 (the biting protrusion 14) is a so-called cutting operation (eye-cutting operation) in which chisel is driven into the contact surface 13 of the washer 1 by human power or a machine as employed in, for example, a file manufacturing process. It can be formed by standing work) and subsequent quenching work. On the other hand, the surface of the washer 1 that contacts the nut 3 is a smooth smooth contact surface 16.

  FIG. 3 shows the result of measuring the contour shape of the washer 1 along the line AA in FIG. 2 using a tracer (shape contour measuring instrument), and FIG. 4 shows the washer 1 taken along the line AA in FIG. It is the figure which cut | disconnected along and showed the cross-sectional shape seen from the side surface.

  As shown in FIGS. 3 and 4, the contact surface 13 of the washer 1 is formed with a recess 14a on the front side in a direction in which a later-described washer tries to rotate (hereinafter also simply referred to as a washer rotating direction). A biting protrusion 14 is formed so as to protrude from the bottom of the recess 14a to a position higher than the contact surface 13 of the washer 1 by 0.2 mm or more on the rear side in the washer rotation direction. Two biting protrusions 14 are provided side by side in the circumferential direction of the washer 1. In the example of FIG. 4, the height H from the contact surface 13 of the biting protrusion 14 is 0.26 mm, and the depth D from the contact surface 13 of the recessed portion 14a is 0.48 mm.

  The biting protrusion 14 has a substantially triangular shape in a side sectional view, is inclined on the front side in the washer rotation direction, bites into the steel material 51, press-contacts with the steel material 51, the surface of the pressure-contacting portion 14 b, and the biting protrusion 14. And an inclined portion 14c that inclines toward the rear side in the washer rotation direction so as to continue through the apex. Here, the pressure contact portion 14b extends so as to continue to the inside of the depression 14a, and the inclination angle of the surface of the pressure contact portion 14b with respect to the contact surface 13 is greater than the inclination angle of the surface of the inclination portion 14c with respect to the contact surface 13. It is also configured to be large and steep.

  In addition, although the biting protrusion 14 is projected so as to be 0.2 mm or more in height from the contact surface 13, it is not limited to this. Specifically, when the nut 3 (bolt 2) and the steel materials 51 and 52 are fastened by the fastening tool 4, it is possible to bite into the fastened member and receive the reaction force, and to prevent the washer 1 from rotating together. For example, it is preferable that the height of the biting protrusion 14 from the contact surface 13 is 0.1 mm or more and 1 mm or less. Further, at least one biting protrusion 14 in the protrusion group 15 may be formed to have a predetermined height or more (for example, 0.1 mm or more or 0.2 mm or more). The same effect as in the case of the shown shape can be obtained.

(Action when fastening)
With reference to FIG. 1, the operation of the washer according to the fastening of the fastening member and the fastened member will be described in detail.

  First, the steel material 51 and the steel material 52 are overlapped so that the screw insertion holes 51a of the steel material 51 and the screw insertion holes 52a of the steel material 52 are aligned. The screw shaft 21 of the bolt 2 is inserted into the screw insertion holes 51a and 52a from the lower side in FIG. 1, and the contact surface 13 provided with the projection group 15 (the biting projection 14) from the upper side in FIG. The washer 1 is extrapolated so as to be on the steel material 51 side. Thereafter, the nut 3 is attached from the upper side of the screw shaft 21 of the bolt 2 protruding upward from the washer 1.

  Next, the inner socket 42 of the fastening tool 4 is engaged with the nut 3, and the outer case 43 is engaged with the engaging portion 12 of the washer 1. In this state, when the inner socket 42 is rotationally driven by rotating the motor 45, the nut 3 is rotated and the tightening operation is started.

  As the tightening of the nut 3 proceeds, each biting protrusion 14 of the washer 1 bites into the steel material 51. Specifically, turning force in the rotation direction and axial force in the thickness direction of the washer 1 are applied to the washer 1, and the steel member gradually becomes pressed while the pressure contact portion 14b of the biting protrusion 14 is in pressure contact with the steel material. Cut into 51. On the other hand, since the washer 1 is in contact with the nut 3 via the smooth contact surface 16, it is easy to slip between the washer 1 and the nut 3, and there is no co-rotation related to the tightening of the nut 3. .

  In the above-described tightening process, for example, when tightening with high torque, a large reaction force is applied to the fastening tool 4, but the outer case 43 integrally fixed to the tool body 41 is engaged with the washer 1. Since it is engaged with the portion 12, the reaction force can be released to the steel material 51 side via the press contact portion 14b provided on the biting protrusion 14 of the washer 1, that is, the washer can receive the reaction force. Therefore, it is possible to prevent the reaction force from being transmitted to the user.

  Furthermore, the angle between the contact surface 13 (surface) of the washer 1 and the pressure contact portion 14b surface of the biting protrusion 14 is larger than the angle between the contact surface 13 and the inclined portion 14c surface of the washer 1 and suddenly. Therefore, the press contact portion 14 b is firmly pressed by the steel material 51. Further, since the inclined portion 14c is gently inclined, the volume of the inclined portion 14c can be ensured. Thereby, when the steel material 51 is hard, even when an axial force and a force in the direction opposite to the washer rotating direction are applied to the washer 1 at the time of fastening, the biting protrusion 14 is firmly crushed without being crushed. And the steel material 51.

  The angle between the contact surface 13 of the washer 1 and the surface of the pressure contact portion 14b of the biting projection 14 is not particularly limited, and the biting projection 14 bites into the steel material 51 and is pressed when tightened by the fastening tool 4. It is only necessary that the angle is set. For example, it is preferably set to 60 degrees or more and 90 degrees or less, but may be less than 60 degrees or 90 degrees or more. Similarly, the angle between the contact surface 13 of the washer 1 and the surface of the inclined portion 14c of the biting protrusion 14 is not particularly limited, but is gentler than the angle between the contact surface 13 of the washer 1 and the surface of the press contact portion 14b. It is preferable that the setting is made. For example, it is preferably set to 5 degrees or more and 30 degrees or less, but may be set to 30 degrees or more.

  Tables 1 and 2 below show the results of the tightening test. The tightening test was performed with three samples (the bolt used is F10T M22 × 85), and the torque coefficient value was calculated based on the measured values of torque and axial force related to tightening with primary tightening and standard bolt tension. ing. Table 1 is a table showing torque coefficient values in primary tightening (150 N · m), and Table 2 is a table showing torque coefficient values in standard bolt tension (226 kN).

  When the washer 1 is not provided with the biting projection 14, the torque coefficient value is about 0.13 to 0.14. Therefore, by providing the washer projection 14 on the washer 1, primary tightening (150 N · m) and It can be seen that very high torque coefficient values are obtained for both standard bolt tensions.

  As described above, according to the present embodiment, when the fastening tool 4 is tightened, each biting projection 14 of the washer 1 receives the axial force and bites into the steel material 51, and the biting projection 14 is interposed via the pressure contact portion 14b. Since the outer case 43 and the engaging portion 12 of the washer 1 are engaged with each other when the fastening tool 4 is tightened, the washer is 1 can receive the reaction force, and the reaction force related to the tightening can be prevented from being transmitted to the operator.

-Second Embodiment-
FIG. 7 shows a tightened state of the fastening structure 6 according to the present embodiment. Specifically, as in the first embodiment, the steel materials 51 and 52 are fastened using the washer 1, the bolt 2, and the nut 3.

  The bolt 2 includes a screw shaft 21 and a head portion 22 as in the first embodiment. The screw shaft 21 is provided at an end portion (upper side in FIG. 7) in the tightening direction of the screw shaft 21. Engaging portion 21b and a notch 21c as a weak portion that is provided on the opposite side of the tightening direction (lower side in FIG. 7) from the engaging portion 21b and breaks when a torque of a predetermined level or higher is applied to the engaging portion 21b. And are provided.

  The inner socket 42 has an opening 42 a that opens to be engaged with the engaging portion 21 b of the screw shaft 21 on one end side. Further, the opening 43 a of the outer case 43 is formed in a shape (for example, a hexagonal shape) that is slightly larger than the outer shape of the nut 3. The fastening tool 4 is configured such that the outer case 43 and the nut 3 are engaged when the engaging portion 21b of the screw shaft 21 and the inner socket 42 are engaged.

  As shown in FIG. 8, the washer 1 is a circular flat plate having a screw insertion hole 11 in the center, and is disposed between the nut 3 and the steel material 51 as shown in FIG. 7.

  The fastening structure 6, the fastening tool 4, and the structure of the washer 1 (the shape of the biting protrusion) other than those described above are the same as or similar to those of the first embodiment, and detailed description thereof is omitted here.

(Action when fastening)
With reference to FIG. 7, the action of the washer related to the fastening of the fastening member and the fastened member will be described in detail.

  First, as in the first embodiment, the steel material 51 and the steel material 52 are overlapped, and the screw shaft 21 of the bolt 2 is inserted into the screw insertion holes 51a and 52a from the lower side of FIG. The washer 1 is extrapolated from the upper side so that the contact surface 13 provided with the projection group 15 (the biting projection 14) is on the steel material 51 side. Thereafter, the nut 3 is attached (screwed) from the upper side of the screw shaft 21 of the bolt 2 protruding upward from the washer 1.

  Next, the inner socket 42 of the fastening tool 4 is engaged with the engaging portion 21 b of the screw shaft 21 and the outer case 43 is engaged with the nut 3. In this state, when the inner socket 42 is rotationally driven by rotationally driving the motor 45, the engaging portion 21b of the screw shaft 21 is rotated and the tightening operation is started.

  As tightening of the fastening structure 6 proceeds, turning force and axial force are applied to the washer 1, and the pressure contact portion 14 b of the biting protrusion 14 gradually bites into the steel material 51 while being pressed against the steel material. On the other hand, it is easy to slip between the washer 1 and the nut 3 as in the first embodiment, and no joint rotation related to the tightening of the nut 3 occurs.

  In the above-described tightening process, a large reaction force is applied to the fastening tool 4, but the outer case 43 is engaged with the nut 3 because the outer case 43 integrally fixed to the tool body 41 is engaged with the nut 3. The inner socket 42 is rotated in the opposite direction (tightening direction) to the rotation direction. That is, since the reaction force can be used for tightening the nut 3, the reaction force can be prevented from being transmitted to the user.

  When the fastening structure 6 is further tightened and a torque of a predetermined value or more is applied to the engaging portion 21b of the screw shaft 21, the notch 21c is broken and the fastening of the fastening structure 6 is completed. Thus, by providing the notch 21c in the screw shaft 21, the tightening torque can be managed so as to be within a predetermined range.

  The result of the tightening test is the same as or similar to that of the first embodiment, and a detailed description thereof is omitted here.

  As described above, according to the present embodiment, when the fastening tool 4 is tightened, the screw shaft 21 of the bolt 2 and the nut 3 are relatively rotated by the rotational force and reaction force of the fastening tool 4. The reaction force related to tightening can be prevented from being transmitted to the operator. Furthermore, since the pressure contact portion of the washer receives a reaction force applied to the washer (force applied in the direction of rotating the washer), the washer does not rotate together, and the torque coefficient value is within a predetermined variation range obtained by a tightening test or the like. be able to.

  While the preferred embodiments of the present invention have been described above, various modifications are possible.

-Modification-
In the washer 1 according to the above-described embodiment, the outer shape of the washer 1 is a hexagon, but is not limited thereto. For example, other polygons such as an octagon and a dodecagon may be used. Furthermore, the washer 1 is not limited to a polygon, and the outer shape may be a shape other than a polygon as long as the washer has an engagement portion configured to be able to engage with the outer case. . For example, as shown by solid lines or phantom lines in FIGS. 6A and 6B, the outer shape of the washer 1 is substantially circular, and a part of the washer is cut out on a straight line or an arc so that the engaging portion 12 is formed. The shape may be formed. Also in this case, the position of the biting protrusion 14 may be closer to the center of the washer 1 as shown in FIG. 6A, or the position of the biting protrusion 14 may be closer to the washer as shown in FIG. 6B. 1 may be close to the outer periphery, and the same effect as the above-described embodiment can be obtained.

  The washer according to the present disclosure is configured so as to be able to receive a reaction force from a fastening tool, and can prevent the reaction force from being transmitted to an operator. The nature is high.

DESCRIPTION OF SYMBOLS 1 Washer 12 Engagement part 13 Contact surface 14 Biting protrusion 14a Recessed part 14b Pressure contact part 14c Back side inclined surface 15 Protrusion group 3 Nut (fastening member)
4 Fastening tool 41 Tool body 42 Inner socket 43 Outer case 51 Steel (fastened member)

Claims (5)

A washer disposed between a fastening member and a fastened member to be fastened by turning of the inner case of a fastening tool in which the inner case turns in the outer case,
The outer peripheral portion is provided with an engaging portion that engages with the outer case of the fastening tool,
In order to prevent the outer case from rotating due to a reaction force, the contact surface with the member to be fastened is pressed against the member to be fastened while being bitten into the member to be fastened when tightened by the fastening tool. a plurality of biting projections is projected,
In the plurality of biting protrusions, two or three biting protrusions are arranged close to each other in the circumferential direction, and two to four protrusion groups are configured by the biting protrusions arranged close to each other.
The washer characterized in that the projection groups are arranged at a predetermined angular pitch in the circumferential direction . The washer according to claim 1,
The plurality of biting protrusions are respectively pressed against the apex of the biting protrusion, the pressure contact portions positioned on the front side in the rotation direction in which the washer is about to rotate as the inner case rotates. An inclined surface that continues through the apex of the biting protrusion on the surface,
The washer characterized in that an inclination angle of the surface of the pressure contact portion with respect to the contact surface is larger than an inclination angle of the inclined surface with respect to the contact surface. The washer according to claim 2,
In the plurality of biting projections, a depression portion that is recessed from the contact surface is formed on the front side of the rotation direction of each of the biting projections, and the pressure contact portion surface extends to the inside of the depression portion. A washer characterized by its extension. In the washer according to any one of claims 1 to 3,
Each of the plurality of biting protrusions has a height from the contact surface of 0.2 mm or more. In the washer according to any one of claims 1 to 4,
Each of the plurality of biting protrusions extends in the radial direction of the washer and is provided at a portion near the center of the washer.