JP5864339B2 - Fastening structure and fastening method - Google Patents

Description

  The present invention relates to a fastening structure and a fastening method in which a plurality of members (fastened bodies) constituting a structure or the like are fastened using bolts, washers, and nuts.

  With respect to a fastening structure in which a fastened body is fastened using bolts, washers, and nuts, one of the inventors of the present application disclosed a washer with a specific shape in order to enable strong fastening in Patent Documents 1 and 2, etc. (Washer) and a specially shaped nut are proposed.

  The fastening structure 101 shown in FIG. 7 is a basic fastening structure similar to that described in Patent Documents 1 and 2. The fastened bodies 108 and 109 have fastening insertion holes 108A and 109A. The bolt 102 has a male screw part 121 and a head part 122. The washer 103 has a base portion 131 and a protruding portion 132 protruding from the central portion of the base portion 131. The protruding portion 132 is axisymmetric and has a substantially trapezoidal shape in side view, and a bolt insertion hole 133 that is eccentric from the central axis of the protruding portion 132 is formed at the center thereof. The nut 104 is formed with a concave portion 142 that is axially symmetric and has a substantially trapezoidal shape in cross section around one opening (downward in FIG. 7) of the female screw portion 141.

  As a fastening method, first, the male screw portion 121 of the bolt 102 is inserted into the fastening insertion holes 108A and 109A of the fastened bodies 108 and 109 and the bolt insertion hole 133 of the washer 103, and screwed into the female screw portion 141 of the nut 104. . Then, by rotating the nut 104 with respect to the bolt 102, the concave portion 142 of the nut 104 is brought into contact with the protruding portion 132 of the washer 103 and fitted, and the inner peripheral edge 133 a of the bolt insertion hole 133 of the washer 103 is fitted. The part is brought into contact with a part of the male screw part 121 of the bolt 102 (see the center right side in FIG. 7). According to the fastening structure that has been fastened, a part of the inner peripheral edge 133a of the bolt insertion hole 133 of the washer 103 comes into contact with and engages with a part of the male thread 121 of the bolt 102, so that the washer 103 is strongly coupled to the bolt 102. Thus, a loosening prevention effect can be obtained.

JP 2002-206515 A JP 2007-211892 A

  By the way, in order to obtain a fastening structure in which the fastened body is well fastened, it is important to make the axial force (tensile force applied in the axial direction of the bolt) appropriate. On site, set an appropriate maximum tightening torque when tightening the nut based on the relationship that the tightening torque (force required for tightening) increases and the axial force increases as the nut is tightened. In general, an appropriate axial force is realized.

  However, when the washer 103 and the nut 104 having the specific shape of the fastening structure described above are used, the operation of the washer 103 and the nut 104 when tightening the nut is not simple. Thus, it may be difficult to obtain a desired axial force.

  For example, what is shown in FIG. 8 is a characteristic diagram of a sample in which the tightening torque and the axial force are simply, that is, monotonic or close to a monotonous curve, even if the nut 104 is tightened and tightened. is there. The vertical axis represents tightening torque (curve a, unit: Nm) and axial force (curve b, unit: KN). The horizontal axis is a nut rotation angle (unit: degree) for turning the nut 104. In this sample washer 103, the bottom surface 131a of the base portion 131 has an inclination of about 18 degrees inward from the outer peripheral edge 131b, and the nut 104 has an inclination angle of the side surface 142a of the concave portion 142 of the washer 103. This is smaller than the inclination angle of the side surface 132a of the protrusion 132. The nut 104 is the size of M12.

  In this sample, the axial force is not so large, and if the maximum tightening torque is set to 60 Nm, which is a numerical value used in other general cases using an M12 nut, the axial force is about 15 KN. . In addition, when the tightening torque is in the range of about 40 to 55 Nm, the tightening torque and the axial force show a peculiar change. It is better to set the torque to be somewhat larger than 60 Nm.

  SUMMARY OF THE INVENTION The present invention has been made in view of such a reason, and an object of the present invention is to tighten a nut when tightening a nut in a fastening structure and a fastening method in which a plurality of fastened bodies are fastened using bolts, washers, and nuts. An object of the present invention is to provide an apparatus in which an attaching torque and an axial force are simply increased and an appropriate axial force can be easily obtained with an appropriate maximum tightening torque.

In order to achieve the above object, a fastening structure according to claim 1 is in surface contact with a plurality of fastened bodies having fastening insertion holes, bolts having male screw portions and a head, and the fastened body. A base portion having a bottom surface and a projecting portion that protrudes from the central portion of the base portion and is axially symmetric and has a substantially trapezoidal shape when viewed from the side are formed with bolt insertion holes that are eccentric from the central axis of the projecting portion. A recessed portion having an axial symmetry and a substantially trapezoidal shape in cross section is formed around one opening of the female screw portion and the female screw portion, and the inclination angle of the side surface of the concave portion is larger than the inclination angle of the side surface of the protruding portion of the washer it comprises a nut, the external thread portion of the bolt is inserted into the bolt insertion holes of the fastening through hole and the washer of the fastened member, the female screw portion of the nut is screwed to the male screw portion It is a fastening structure, and the side surface of the recess of the nut A portion of the inner periphery of the bolt insertion hole of the washer is in contact with a portion of the male thread portion of the bolt, and the nut is the bolt It is characterized by being inclined with respect to.

The fastening method according to claim 2 includes: a bolt having a male screw portion and a head ; a base having a bottom surface that comes into surface contact when placed on a body to be fastened; and an axially symmetric side surface projecting from a central portion of the base. A washer having a substantially trapezoidal shape, a washer having a bolt insertion hole formed eccentrically from the central axis of the protrusion, and an axially symmetrical periphery of one opening of the female screw part; A plurality of objects to be fastened having a fastening through-hole using a nut having a substantially trapezoidal recess in cross-section, and a nut having an inclination angle of a side surface of the recess larger than an inclination angle of a side surface of the protruding portion of the washer The male screw portion of the bolt is inserted into the fastening insertion hole of the fastened body and the bolt insertion hole of the washer, and the female screw portion of the nut is screwed into the male screw portion. As the nut is turned and tightened, the recess of the nut The side surface is brought into contact with the corner portion of the protruding portion of the washer to be fitted, and a part of the inner peripheral edge of the bolt insertion hole of the washer is brought into contact with a part of the male screw portion of the bolt, and the nut is attached to the bolt. It is characterized in that it is tilted with respect to it and tightening is completed when a set maximum tightening torque is reached.

  According to the fastening structure and fastening method of the present invention, the tightening torque and the axial force are simply increased as the nut is turned and tightened, and an appropriate axial force can be easily obtained with an appropriate maximum tightening torque. .

It is a side view sectional view showing the conclusion structure concerning an embodiment of the present invention. The washer used for the fastening structure same as the above is shown, (a) is a plan view and (b) is a side view sectional view. The nut used for a fastening structure same as the above is shown, (a) is a side view sectional view, (b) is a bottom view. It is side view sectional drawing which shows the state in the middle of fastening of the fastening structure same as the above. It is side view sectional drawing which shows the other state in the middle of the fastening of the fastening structure same as the above. It is a characteristic view of the example of the sample using a fastening structure same as the above. It is sectional drawing seen from the side which shows the conventional fastening structure. It is a characteristic view of the example of the sample using the conventional fastening structure.

  Embodiments of the present invention will be described below. As shown in FIG. 1, the fastening structure 1 according to the embodiment of the present invention includes a plurality of fastened bodies 8 and 9, bolts 2, washers (washers) 3, and nuts 4. The fastened bodies 8 and 9 have fastening insertion holes 8A and 9A. The bolt 2 has a male screw portion 21 and a head portion 22, and may be a widely used general-purpose product. In the fastening structure 1, the male screw portion 21 of the bolt 2 is inserted into the fastening insertion holes 8 </ b> A and 9 </ b> A of the fastened bodies 8 and 9 and the bolt insertion hole 33 described later of the washer 3. The female thread portion 41 is screwed.

  As shown in FIG. 2, the washer 3 has a base portion 31 and a protruding portion 32 that protrudes from the central portion of the base portion 31. The base 31 has a bottom surface (back surface) 31 a that comes into surface contact with the base body 9 when it is placed on the fastened body 9. That is, the bottom surface 31a of the base 31 is formed so as not to have a gradient inward from the outer peripheral edge 31b.

  The protrusion 32 is axisymmetric and has a substantially trapezoidal shape in side view, and a bolt insertion hole 33 that is eccentric from the central axis X of the protrusion 32 is formed at the center. The axial symmetry means symmetry with respect to the central axis X of the protrusion 32.

  In detail, the surface of the protrusion part 32 consists of the side surface 32a and the top surface 32b. The side surface 32a is inclined at an inclination angle φ with respect to the axial direction (the direction of the central axis X), and the top surface 32b is orthogonal to the axial direction. The inclination angle φ of the side surface 32a can be about 15 degrees, for example.

  Since the bolt insertion hole 33 is decentered from the central axis X of the protrusion 32 as described above, as shown in FIG. 2A, the boundary between the side surface 32a and the top surface 32b of the protrusion 32 is shown in plan view. The center position i of the circle drawn by the corner 32c is on the center axis X, and the center position j of the circle drawn by the peripheral edge 33a of the bolt insertion hole 33 is shifted from the center position i. In FIG. 2B, the axis passing through the point j is shown as the central axis Y.

  In the nut 4, a concave portion 42 that is axially symmetric and has a substantially trapezoidal shape in cross section is formed around the opening of one of the female screw portions 41 (downward in FIG. 3A). The inclination angle θ of the side surface 42 a of the recess 42 is larger than the inclination angle φ of the side surface 32 a of the protrusion 32 of the washer 3. Axisymmetric means symmetrical about the central axis T of the nut 4.

  Specifically, as shown in FIG. 3, the nut 4 has a prismatic shape (for example, a regular hexagonal prism), and the female screw portion 41 that engages with the male screw portion 21 of the bolt 2, which is a general-purpose product, has a central axis T It is formed along. The recess 42 includes the side surface 42a and the bottom surface 42b described above. As described above, the side surface 42a is inclined at an inclination angle θ with respect to the axial direction (the direction of the central axis T), and the bottom surface 42b is orthogonal to the axial direction. The size of the recess 42 in plan view is such that when the nut 4 overlaps the washer 3, the corner portion 32 c of the protrusion 32 of the washer 3 can contact the side surface 42 a of the recess 42 of the nut 4.

  Since the inclination angle θ of the side surface 42 a of the recess 42 of the nut 4 is larger than the inclination angle φ of the side surface 32 a of the protrusion 32 of the washer 3 as described above, the protrusion 32 of the washer 3 is recessed in the nut 4. When fitting into 42, the corner 32 c of the protrusion 32 of the washer 3 fits in contact with the side surface 42 a of the recess 42 of the nut 4. The inclination angle θ of the side surface 42a of the recess 42 of the nut 4 can be set to about 17 to 18 degrees, for example.

  A fastening method for fastening the fastened bodies 8 and 9 using such bolts 2, washers 3 and nuts 4 will be described in detail below.

  First, the male threaded portion 21 of the bolt 2 is inserted into the fastening insertion holes 8A and 9A of the fastened body 8 and the fastened body 9 that have been aligned, and as shown in FIG. The male screw portion 21 of the bolt 2 protruding through the fastening insertion hole 9A is inserted into the bolt insertion hole 33 of the washer 3, and the base 31 of the washer 3 is placed in surface contact with the body 9 to be fastened.

  The female screw portion 41 of the nut 4 is screwed into the male screw portion 21 of the bolt 2, and the nut 4 is rotated with respect to the bolt 2. At this time, the central axis T of the nut 4 coincides with the central axis of the bolt 2. As the nut 4 is turned, the protruding portion 32 of the washer 3 gradually enters the concave portion 42 of the nut 4, and eventually the corner portion 32 c contacts the side surface 42 a of the concave portion 42 of the nut 4. It will be in the state fitted to the recessed part 42. FIG.

  Further, when the nut 4 is turned and tightened, the protruding portion 32 of the washer 3 is further depressed while the corner portion 32 c of the protruding portion 32 of the washer 3 receives pressure from the side surface 42 a of the recessed portion 42 of the nut 4. Go into 42. At this time, the tightening torque gradually increases with tightening while being used for this fitting, and the axial force also gradually increases.

  As described above, since the bolt insertion hole 33 of the washer 3 is eccentric from the central axis X of the protrusion 32, the inner peripheral edge 33a of the bolt insertion hole 33 of the washer 3 is shown on the right side of the center of FIG. Part of the screw comes into contact with and meshes with part of the male threaded portion 21 of the bolt 2. As a result, the washer 3 is strongly coupled to the bolt 2.

  Here, the position of contact between the inner peripheral edge 33a of the bolt insertion hole 33 of the washer 3 and the male screw portion 21 of the bolt 2 and the position of contact between the washer 3 (corner portion 32c) and the nut 4 are substantially fixed. Moreover, the line connecting them is substantially perpendicular to the axial direction of the nut 4 (the direction of the central axis T). For this reason, when the nut 4 is further turned and tightened, the axial movement of the nut 4 is subjected to strong resistance in the line, and the nut 4 is gradually inclined with respect to the bolt 2 (see FIG. 1). That is, the central axis T of the nut 4 is gradually rotated from the central axis of the bolt 2. As a result, the friction between the threads of the nut 4 and the bolt 2 increases. The tightening torque gradually increases with tightening while being used for the increased friction, and the axial force also gradually increases.

  When the set maximum tightening torque is reached, the tightening is completed.

  In this way, the fastened bodies 8 and 9 are fastened using the bolt 2, washer 3, and nut 4. Since the bottom surface 31a of the base 31 of the washer 3 is in surface contact with the body 9 to be fastened, and the vicinity of the protruding portion 32 of the bottom surface 31a is in contact with the body 9 to be fastened, the base 31 is always in a constant state. It does not affect the tightening torque and axial force. Further, as the nut 4 is tightened, the protruding portion 32 of the washer 3 fits into the concave portion 42 of the nut 4, and then the nut 4 is inclined with respect to the bolt 2. For this reason, the tightening torque and the axial force are changed simply, i.e., in a monotonous or nearly monotonous curve, without a specific change, and as a result, an appropriate maximum tightening torque is set to obtain an appropriate axial force. Easy to get.

  As shown in FIG. 1, the fastening structure 1 that has been fastened by the fastening method described above has the bottom surface 31 a of the base 31 of the washer 3 in surface contact with the body 9 to be fastened, and the recess 42 of the nut 4. The side surface 42 a is in contact with and fitted to the corner portion 32 c of the protrusion 32 of the washer 3, and a part of the inner peripheral edge 33 a of the bolt insertion hole 33 of the washer 3 is in contact with a part of the male screw portion 21 of the bolt 2. Thus, the nut 4 is inclined with respect to the bolt 2. The fastening structure 1 achieves an appropriate axial force, friction between the nut 4 and the bolt 2 is large, and the coupling between the nut 4 and the bolt 2 is strong.

  FIG. 6 is a characteristic diagram showing an example of changes in tightening torque and axial force when the nut 4 is turned and tightened. The vertical axis represents tightening torque (curve a, unit: Nm) and axial force (curve b, unit: KN). The horizontal axis represents a nut rotation angle (unit: degree) for turning the nut 4. The inclination angle of the side surface 32a of the protrusion 32 of the washer 3 is about 15 degrees, and the inclination angle of the side surface 42a of the recess 42 of the nut 4 is about 17 to 18 degrees. The nut 4 has a size of M12.

  If the maximum tightening torque is set to 60 Nm, an axial force of about 25 KN can be obtained. In addition, the tightening torque and the axial force monotonously increase until the tightening torque reaches about 90 Nm.

  The fastening structure and fastening method according to the embodiment of the present invention have been described above, but the present invention is not limited to those described in the embodiment, and various modifications within the scope of the matters described in the claims. Design changes are possible. For example, the size and fine shape of the protruding portion 32 of the washer 3 and the concave portion 42 of the nut 4 described in the embodiment can be arbitrarily changed according to the environment in which they are used and the body to be fastened. Moreover, it is also possible to use the elastic washer described in Patent Document 2 shown in the background art section.

DESCRIPTION OF SYMBOLS 1 Fastening structure 2 Bolt 21 Male screw part 22 Bolt head 3 Washer 31 Washer base 31a Washer base 31b Outer peripheral edge of washer base 32 Washer protrusion 32a Washer protrusion side 32b Washer side The top surface of the protrusion 32c The corner of the protrusion of the washer 33 The bolt insertion hole of the washer 33a The inner peripheral edge of the bolt insertion hole of the washer 4 Nut 41 The female thread portion of the nut 42 The concave portion of the nut 42a The side surface of the concave portion of the nut 42b The concave portion of the nut Bottom 8, 9 Fastened body 8A, 9A Fastening insertion hole for fastened body

Claims (2)

A plurality of fastened bodies having fastening insertion holes;
A bolt having a male thread and a head;
A base portion having a bottom surface that comes into surface contact with the fastened body, and a projecting portion that protrudes from the center portion of the base portion and is axially symmetric and has a substantially trapezoidal shape when viewed from the side, and the projecting portion from the central axis of the projecting portion A washer formed with an eccentric bolt insertion hole;
A nut that is axially symmetric and has a substantially trapezoidal shape in cross section in the vicinity of one opening of the female screw portion, and a tilt angle of a side surface of the recess is larger than a tilt angle of a side surface of the protruding portion of the washer,
Becomes a, the external thread portion of the bolt is inserted into the bolt insertion holes of the fastening through hole and the washer of the fastened member, the fastening structure internally threaded portion of the nut is screwed to the male screw portion Because
The side surface of the concave portion of the nut is in contact with and fitted into the corner of the protruding portion of the washer, and a part of the inner peripheral edge of the bolt insertion hole of the washer contacts a part of the male screw portion of the bolt. The fastening structure is characterized in that the nut is inclined with respect to the bolt. A bolt having a male thread and a head;
A base portion having a bottom surface that comes into surface contact when mounted on a fastened body , and an axially symmetrical and substantially trapezoidal protrusion portion protruding from the center portion of the base portion; A washer formed with a bolt insertion hole that is eccentric from the central axis of
A nut that is axially symmetric and has a substantially trapezoidal shape in cross section in the vicinity of one opening of the female screw portion, and a tilt angle of a side surface of the recess is larger than a tilt angle of a side surface of the protruding portion of the washer,
A fastening method for fastening a plurality of fastened bodies having fastening through-holes,
Insert the male screw portion of the bolt into the fastening insertion hole of the fastened body and the bolt insertion hole of the washer, and screw the female screw portion of the nut into the male screw portion,
As the nut is turned and tightened, the side surface of the concave portion of the nut is brought into contact with the corner of the protruding portion of the washer to be fitted, and a part of the inner peripheral edge of the bolt insertion hole of the washer is connected to the male screw portion of the bolt The fastening method is characterized in that the nut is tilted with respect to the bolt, and the fastening is completed when a set maximum fastening torque is reached.

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