JP2016153661A - Fastening method, manufacturing method of fastening member, and fastening member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fastening method in which axial force due to a rotational speed of a fastening member is difficult to change, a manufacturing method of a fastening member, and the fastening member.SOLUTION: A first fastening member 16a fastened at a first rotational speed N1 and a second fastening member 16b fastened at a second rotational speed N2 slower than the first rotational speed N1 include a first lubrication layer 34 that has first frictional coefficient stabilizer so as to make a torque coefficient K in the first rotational speed N1 smaller than a torque coefficient K in the second rotational speed N2, and a second lubrication layer 36 that has a second frictional coefficient stabilizer so as to make the torque coefficient K in the second rotational speed N2 smaller than the torque coefficient K in the first rotational speed N1.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fastening method using a fastening member, a method for manufacturing a fastening member, and a fastening member.

  Patent Document 1 provides a fastening member that is rich in rust prevention performance and durability, has a slight influence on a fastened member, and that can satisfy a demand for fastening ability, and a surface treatment method for the fastening member. ([0003] second paragraph, summary). In order to achieve the object, the bolt 2 of Patent Document 1 includes a base material 5 made of a metal material containing iron, a binder 41 containing a silicon compound, and zinc-containing metal flakes 43 and 45. The formed antirust layer 4 and the surface layer 3 including the silicon compound 33 and the synthetic resin 37 and formed on the antirust layer 4 are provided (summary).

  In patent document 1, after forming the surface layer 3 containing the synthetic resin 37 after forming the antirust layer 4 which is rich in durability and antirust performance on the surface of the base material 5, It is possible to suppress the aggressiveness to the fastened member on the contact surface. Furthermore, since both the rust preventive layer 4 and the surface layer 3 contain a silicon compound, the rust preventive layer 4 and the surface layer 3 are firmly bonded, so the durability of the surface layer 3 and the rust preventive layer 4 is increased. And can exhibit rust prevention performance over a long period of time. Further, since the surface layer 3 and the rust preventive layer 4 are not easily damaged even if re-tightening is performed, good fastening ability can be maintained even after multiple removals and re-tightening ([0008] first paragraph).

  Moreover, in patent document 1, the surface layer 3 contains the synthetic resin 37 and the wax 35, so that the friction coefficient of the surface is low, and when this fastening member is tightened, the aggression with respect to the seating surface becomes low, and as a silicon compound By including the colloidal silica 33, a structure in which a silicon compound enters between the synthetic resin 37 and the wax 35 is realized, and a strong bond is generated between the surface layer 3 and the antirust layer 4 to obtain a strong coating. ([0008] second paragraph).

JP 2010-190320 A

  The inventor of the present invention has the same tightening torque when tightening a bolt as an example of a fastening member described in Patent Document 1 with a manual torque wrench and when tightening with an impact driver (electric tool). It was discovered that a difference occurs in the coefficient (details will be described later with reference to FIG. 5). If the torque coefficient is different, the bolt axial force is also different, which may affect the frequency of bolt loosening.

  The present invention has been made in consideration of the above-described problems, and an object thereof is to provide a fastening method, a fastening member manufacturing method, and a fastening member in which a change in the axial force due to the rotation speed of the fastening member does not easily occur. .

The fastening method according to the present invention includes a first fastening step of fixing the first part of the workpiece by rotating the first fastening member at a first rotational speed by the first rotating tool, and the second fastening member by the second rotating tool. A second fastening step of rotating at a second rotational speed lower than that of the first rotary tool to fix the second part of the workpiece,
The first fastening member and the second fastening member are:
A metal substrate;
A rust preventive layer formed on the substrate;
A first lubricating layer formed on the rust preventive layer, including a first friction coefficient stabilizer that lowers the torque coefficient at the first rotational speed than the torque coefficient at the second rotational speed;
A second friction coefficient stabilizer that lowers the torque coefficient at the second rotation speed than the torque coefficient at the first rotation speed, and a second lubrication layer formed on the first lubrication layer. It is characterized by.

  According to the present invention, the torque coefficient at the first rotational speed (> second rotational speed) is made lower by the first lubricating layer than the torque coefficient at the second rotational speed. Further, the torque coefficient at the second rotational speed is made lower than the torque coefficient at the first rotational speed by the second lubricating layer. For this reason, it is possible to keep the torque coefficient low during both high-speed rotation and low-speed rotation.

  Therefore, when the first fastening member and the second fastening member are fastened by the first rotary tool and the second rotary tool having different rotational speeds, the torque coefficients of the first fastening member and the second fastening member can be brought closer. . Therefore, a stable axial force can be obtained regardless of the tightening method.

  Further, even when the rotational speed is different, the variation in torque coefficient is reduced. For this reason, it is possible to simplify the confirmation process or the test process due to the variation in the torque coefficient to reduce the number of man-hours for the operator or to reduce the size of the first rotary tool and the second rotary tool.

  When the first rotary tool is an electric tool and the second rotary tool is a manual tool, the first rotational speed is any value between 200 and 8000 revolutions per minute, and the second rotational speed is It may be any value from 1 to 30 revolutions per minute. Thereby, in any of the case where the 1st fastening member is fastened using an electric tool, and the case where the 2nd fastening member is fastened using a manual tool, in the state where the influence of the torque coefficient by rotation speed was reduced, A stable axial force can be obtained.

  The first friction coefficient stabilizer may include, for example, a first lubricant and a synthetic resin. The first lubricant can be, for example, a silicon compound such as colloidal silica. The synthetic resin can be, for example, an acrylic resin, a methacrylic resin, an epoxy resin, a phenol resin, a ketone resin, or other aqueous / non-aqueous resins. The second friction coefficient stabilizer may include, for example, a second lubricant that is a water-soluble plastic working oil or a water-soluble wax.

  A torque coefficient of the first fastening member when the first fastening member is fastened by being rotated at the first rotational speed by the first rotary tool is defined as a first torque coefficient, and the second torque is obtained by the second rotary tool. When a torque coefficient of the second fastening member when the second fastening member is fastened by rotating at a rotational speed is defined as a second torque coefficient, a difference between the first torque coefficient and the second torque coefficient is predetermined. It may be within the range. The predetermined range here can be set to any value between 0.01 and 0.02, for example.

  Thereby, even when the first fastening member and the second fastening member are fastened by the first rotary tool and the second rotary tool having different rotational speeds, the range of the difference between the first torque coefficient and the second torque coefficient is limited. Thus, a stable axial force can be obtained.

  The workpiece may be, for example, a vehicle suspension arm. This makes it easier to maintain a suitable fastening even in a suspension arm to which a relatively large load is frequently applied.

The fastening member manufacturing method according to the present invention includes a metal base material, a rust prevention layer formed on the base material, a first lubrication layer formed on the rust prevention layer, and the first lubrication. A fastening member having a second lubricating layer formed on the layer,
The manufacturing method includes:
A rust preventive layer forming step of forming a rust preventive layer by applying and drying a rust preventive agent on the substrate;
A first coefficient of friction stabilization that lowers the torque coefficient when the fastening member is fastened at a first rotational speed higher than the second rotational speed than the torque coefficient when the fastening member is fastened at a second rotational speed. A first lubricating layer forming step in which an agent is applied onto the rust preventive layer and dried to form the first lubricating layer;
A second friction coefficient stabilizer that lowers the torque coefficient at the second rotational speed than the torque coefficient at the first rotational speed is applied to the first lubricating layer to form the second lubricating layer. And a lubricating layer forming step.

The fastening member according to the present invention is:
A metal substrate;
A rust preventive layer formed on the substrate;
A first friction coefficient stabilizer that lowers the torque coefficient when engaged at a first rotational speed higher than the second rotational speed than the torque coefficient when engaged at a second rotational speed; A first lubricating layer formed on the rust layer;
A second friction coefficient stabilizer that lowers the torque coefficient at the second rotation speed than the torque coefficient at the first rotation speed, and a second lubrication layer formed on the first lubrication layer. It is characterized by.

  According to the present invention, it is possible to make it difficult for the axial force to change due to the rotational speed of the fastening member.

It is a schematic structure figure showing simply the fastening system which performs the fastening method concerning one embodiment of the present invention. It is a figure which shows simply the structure of the volt | bolt and nut in the said embodiment. It is a flowchart of the surface treatment method as a part of manufacturing method of the bolt and the nut in the embodiment. It is a flowchart of the fastening method which fastens two site | parts (1st site | part and 2nd site | part) of a workpiece | work using a volt | bolt and a nut as a part of manufacturing method of the vehicle in the said embodiment. It is a figure which shows an example of the rotational speed of the rotary tool regarding the 1st comparative example, the 2nd comparative example, and the said embodiment, and the torque coefficient of the said volt | bolt.

A. One Embodiment [A1. Configuration of Fastening System 10]
(A1-1. Overall configuration of fastening system 10)
FIG. 1 is a schematic configuration diagram schematically showing a fastening system 10 that executes a fastening method according to an embodiment of the present invention. The fastening system 10 includes an electric tool 12 (first rotating tool), a manual ratchet wrench 13 (second rotating tool), a manual torque wrench 14, a bolt 16, a nut 18, and a washer 20.

  In the present embodiment, the workpiece 100 of the fastening system 10 is a vehicle suspension arm. The fastening system 10 includes a power tool 12, a ratchet wrench 13 (hereinafter also referred to as “ratchet 13”), and a torque wrench 14 that allows bolts 16 and nuts 18 to be placed at a plurality of locations of the workpiece 100 (first portion 102, second portion 104, etc.). Use to fasten.

  Hereinafter, the bolt 16 and the nut 18 used for the first part 102 are also referred to as a first bolt 16a and a first nut 18a, and the bolt 16 and the nut 18 used for the second part 104 are referred to as a second bolt 16b and a second nut 18b. Also called. Here, the first bolt 16a and the second bolt 16b will be described on the assumption that the dimensions are the same, but the specifications may be different. Similarly, the first nut 18a and the second nut 18b will be described on the assumption that the dimensions are the same, but the specifications may be different.

  Further, the fastening system 10 includes a surface treatment device 22 that performs surface treatment on the bolt 16 and the nut 18. The surface treatment apparatus 22 includes a first surface treatment unit 24, a second surface treatment unit 26, and a third surface treatment unit 28.

(A1-2. Electric tool 12)
The electric tool 12 is operated by the operator 200 to rotate the first bolt 16 a and fasten the first bolt 16 a to the first nut 18 a at the first portion 102 of the workpiece 100. As the electric tool 12, for example, an impact driver, a driver drill, an electric drill, or a nut runner can be used.

  The impact driver includes an impact mechanism that strikes in the rotational direction, and strongly tightens the first bolt 16a by striking in the rotational direction. The driver drill has a built-in clutch mechanism, and when the specified torque is reached, the driver drill runs idle. The electric drill does not have an impact mechanism and a clutch mechanism. The nut runner is basically used when the nut 18 is tightened, but can also be used for tightening the bolt 16.

  The rotational speed N [rpm] of the electric tool 12 rotates at 200 to 8000 rpm, for example. The possible range of the rotational speed N varies depending on the type of the electric tool 12. For example, when comparing an impact driver and a nutrunner, the impact driver has a higher rotation (for example, 4000 to 8000 rpm), and the nutrunner has a lower rotation (for example, 200 to 800 rpm).

  In FIG. 1, the electric tool 12 is assumed to be operated by the operator 200, but the electric tool 12 may be assembled to a manufacturing apparatus (not shown).

(A1-3. Manual ratchet 13)
The manual ratchet 13 is manually operated by the operator 200 to rotate the second bolt 16 b and fasten the second bolt 16 b to the second nut 18 b at the second portion 104 of the workpiece 100.

(A1-4. Manual torque wrench 14)
The manual torque wrench 14 is used to confirm that the tightening torque of the bolt 16 fastened by the electric tool 12 and the ratchet 13 is a target value.

(A1-5. Bolt 16 and nut 18)
FIG. 2 is a diagram schematically showing the structure of the bolt 16 and the nut 18 in the present embodiment. As shown in FIG. 2, the bolt 16 and the nut 18 include a base material 30, a rust prevention layer 32, a first lubricating layer 34, and a second lubricating layer 36.

  The base material 30 is made of metal made of iron or the like. The rust prevention layer 32 includes a binder 40 containing a silicon compound (hereinafter referred to as “first silicon compound”) and metal flakes 42, and is formed on the substrate 30.

As the first silicon compound, for example, silica (SiO ₂ ), sodium silicate, potassium silicate, lithium silicate, alkali silicone, silicone emulsion, or water-soluble silicone can be used.

As the metal flake 42, for example, one kind or plural kinds of aluminum flakes, zinc flakes, aluminum alloy zinc flakes, aluminum-SiO ₂ -zinc alloy flakes, nickel mixed zinc flakes, and cobalt mixed zinc flakes can be used.

  As a rust preventive agent containing the binder 40 and the metal flakes 42, for example, Geomet (registered trademark) manufactured by NOF Metal Coatings Co., Ltd. can be used.

  The first lubricating layer 34 includes a first lubricant 44, a synthetic resin 46, and a colorant 48 and is formed on the rust prevention layer 32. As the first lubricant 44, a silicon compound (hereinafter referred to as “second silicon compound”) can be used. As the second silicon compound, for example, colloidal silica can be used.

  As the synthetic resin 46, for example, an acrylic resin, a methacrylic resin, an epoxy resin, a phenol resin, a ketone resin, and other aqueous / non-aqueous resins can be used.

  The coating agent including the first lubricant 44, the synthetic resin 46, and the colorant 48 is a friction coefficient stabilizer that stabilizes the friction coefficient in the first lubricant layer 34 (hereinafter also referred to as “first friction coefficient stabilizer”). is there. As the first friction coefficient stabilizer, for example, PLUS series (plus XL, etc.) manufactured by NOF Metal Coatings Co., Ltd. can be used.

  As the base material 30, the rust prevention layer 32, and the first lubricating layer 34, for example, those described in Patent Document 1 may be used. The first lubricating layer 34 may include a wax similar to the polyethylene wax 35 of Patent Document 1. As the wax here, for example, polyethylene wax, various hydrocarbon resins (polypropylene, polystyrene, etc.), urethane resin, or paraffin can be used.

  The second lubricant layer 36 is made of the second lubricant alone and is formed on the first lubricant layer 34. As a 2nd lubricant, it is a layer which consists of 2nd friction coefficient stabilizers, such as plastic processing oil (water-soluble) and water-soluble wax, for example. As the plastic working oil, for example, Iloform PS 514 manufactured by BP Japan Co., Ltd. can be used.

  Moreover, as a water-soluble wax used for a 2nd lubricant, the thing similar to the 1st lubricating layer 34 can be used, for example. However, the second lubricant needs to have a low friction coefficient in a region where the rotational speed N is relatively low.

(A1-6. Surface treatment apparatus 22)
The surface treatment apparatus 22 forms the rust prevention layer 32, the first lubricating layer 34, and the second lubricating layer 36 on the base material 30 (bolt base material) of the bolt 16 and the base material 30 (nut base material) of the nut 18, respectively. . That is, the first surface treatment unit 24 of the surface treatment apparatus 22 forms the rust prevention layer 32 on the base material 30. The second surface treatment unit 26 forms the first lubricating layer 34 on the rust prevention layer 32. The third surface treatment unit 28 forms the second lubrication layer 36 on the first lubrication layer 34.

  In FIG. 1, the surface treatment apparatus 22 is illustrated as a single apparatus, but may be configured from a separate unit for each surface treatment. Moreover, in FIG. 1, the electric tool 12, the ratchet 13, the torque wrench 14, and the surface treatment apparatus 22 are shown together. However, the surface treatment of the bolts 16 and the nuts 18 by the surface treatment device 22 and the fastening using the electric power tool 12, the ratchet 13, and the torque wrench 14 can be performed in different facilities.

[A2. Manufacturing method of bolt 16 and nut 18 (surface treatment method)]
FIG. 3 is a flowchart of the surface treatment method as a part of the manufacturing method of the bolt 16 and the nut 18 in the present embodiment. The rust prevention layer 32, the first lubricating layer 34, and the second lubricating layer 36 can be formed on the bolt 16 and the nut 18 through the method of FIG. Note that the method of FIG. 3 is executed by the surface treatment apparatus 22. The worker 200 may perform a part of the work for forming the rust prevention layer 32, the first lubricating layer 34, and the second lubricating layer 36.

  In step S1 of FIG. 3, the first surface treatment unit 24 of the surface treatment device 22 has a rust inhibitor (binder 40 and metal flakes 42) on the base material 30 (bolt base material and nut base material) of the bolt 16 and the nut 18. ) To form a rust prevention layer 32. For example, in step S <b> 1, the bolt 16 and the nut 18 are immersed in a rust inhibitor (treatment aqueous solution) containing a first silicon compound that is a component of the binder 40 and the metal flakes 42, and the rust inhibitor is applied. At this time, after immersing in the rust preventive agent, the bolt 16 and the nut 18 are rotated at a predetermined rotation speed [rpm] for a predetermined time [sec] by a centrifuge (not shown), thereby removing the excess rust preventive agent. Good.

  In step S2, the first surface treatment unit 24 dries the rust preventive agent (rust preventive layer 32). At this time, the bolt 16 and the nut 18 may be baked. Steps S1 and S2 may be repeated. By steps S1 and S2, for example, the rust prevention layer 32 having a film thickness of 5 to 15 μm is formed.

  In step S <b> 3, the second surface treatment unit 26 of the surface treatment apparatus 22 applies the first friction coefficient stabilizer (the first lubricant 44, the synthetic resin 46, and the colorant 48) on the rust prevention layer 32 and performs the first operation. The lubrication layer 34 is formed. For example, in step S3, the first friction coefficient stabilizer is applied by immersing the bolt 16 and the nut 18 after forming the rust prevention layer 32 in the first friction coefficient stabilizer in the emulsion state. At this time, the excess first friction coefficient stabilizer may be removed using a centrifuge as in step S1.

  In step S4, the second surface treatment unit 26 dries the first friction coefficient stabilizer (first lubricating layer 34). By steps S3 and S4, for example, the first lubricating layer 34 having a film thickness of 1 to 3 μm is formed.

  In step S <b> 5, the third surface treatment unit 28 of the surface treatment apparatus 22 applies the second friction coefficient stabilizer on the first lubrication layer 34 to form the second lubrication layer 36. The third surface treatment unit 28 applies the second friction coefficient stabilizer by immersing the bolt 16 and the nut 18 in a second friction coefficient stabilizer filled in a container (not shown). At this time, as in step S1, an excess second friction coefficient stabilizer may be removed using a centrifuge.

  In step S6, the second friction coefficient stabilizer (second lubricating layer 36) is dried. By steps S5 and S6, for example, the second lubricating layer 36 having a film thickness of 1 to 3 μm is formed.

  As described above, in the present embodiment, in addition to the rust prevention layer 32 and the first lubricating layer 34, the second lubricating layer 36 is formed. As a result, it is possible to make it difficult for the axial force Ff to change due to the rotational speed N of the bolt 16. Details will be described later with reference to FIG.

[A3. Method of fastening bolt 16 and nut 18]
FIG. 4 is a flowchart of a fastening method for fastening two parts (first part 102 and second part 104) of the workpiece 100 using bolts 16 and nuts 18 as a part of the vehicle manufacturing method in the present embodiment. It is. The workpiece 100 (suspension arm) can be fixed using the bolt 16 and the nut 18 through the method of FIG. The example in FIG. 4 is an example in which two parts of the workpiece 100 are fastened with the bolts 16 and the nuts 18, but the fastening parts are not limited to two places, and may be one place or three places or more.

  In step S <b> 11 of FIG. 4, the worker 200 fastens the bolt 16 to the nut 18 using the electric tool 12 for the first portion 102. At this time, the rotational speed N of the electric tool 12 (hereinafter also referred to as “first rotational speed N1”) is, for example, 200 to 8000 rpm. The tightening torque T of the electric power tool 12 is hereinafter referred to as “first tightening torque T1” or “first torque T1”.

  In step S <b> 12, the worker 200 fastens the bolt 16 to the nut 18 using the ratchet 13 for the second portion 104. At this time, the rotation speed N of the ratchet 13 (hereinafter also referred to as “second rotation speed N2”) is, for example, 1 to 30 rpm. Further, the tightening torque T (hereinafter referred to as “second tightening torque T2” or “second torque T2”) by the ratchet 13 is set to a value equivalent to the first torque T1.

  In step S <b> 13, the worker 200 confirms whether or not the first torque T <b> 1 in the first portion 102 is equal to or higher than the target torque Ttar using the torque wrench 14. In step S <b> 14, the worker 200 confirms whether or not the second torque T <b> 2 in the second portion 104 is equal to or higher than the target torque Ttar using the torque wrench 14. If the combination of steps S11 and S13 and the combination of steps S12 and S14 are ensured, steps S11 to S14 can be performed in an order different from that in FIG.

[A4. Fastening characteristics of bolt 16 and nut 18]
FIG. 5 is a diagram illustrating an example of the rotational speed N of the rotary tool and the torque coefficient K of the bolt 16 according to the first comparative example, the second comparative example, and the present embodiment. The first comparative example is an example in which only the second lubricating layer 36 in the present embodiment is formed on the bolt 16 and the nut 18. The second comparative example is an example in which only the rust prevention layer 32 and the first lubricating layer 34 in the present embodiment are formed on the bolt 16 and the nut 18. In the examples of FIG. 5, the bolts 16 are tightened with the same tightening torque T, and the number of times of tightening is the first. The example of FIG. 5 schematically shows a tendency of an actual detection value.

In relation to the torque coefficient K, the axial force Ff [N] acting on the bolt 16 is expressed by the following equation (1).
Ff = T / (K · d) (1)

  In the above formula (1), T is a tightening torque [N · m] acting on the bolt 16, and d is a nominal diameter [mm] of the bolt 16. As can be seen from equation (1), the smaller the torque coefficient K, the greater the axial force Ff, and the bolt 16 can be firmly fixed.

  In FIG. 5, in the characteristic 300 of the first comparative example (only the second lubricating layer 36), the torque coefficient K is low and excellent at a relatively low rotation (for example, 1 to 10 rpm), but relatively high rotation (for example, 3000 rpm). The torque coefficient K suddenly increases and gets worse. For example, in the characteristic 300, the torque coefficient K at a relatively high rotational speed exceeds 0.13 and increases to around 0.2. This is presumably because a part of the second lubricating layer 36 disappears at a relatively high rotation.

  As a reason why a part of the second lubricating layer 36 disappears, for example, the following can be considered. That is, at the time of high rotation, the vibration of the bolt 16 increases and the local surface pressure rises. On the other hand, since the second lubricating layer 36 is relatively soft, the second lubricating layer 36 is peeled off by contact with the electric power tool 12. In other words, as compared with the first lubricating layer 34, the second lubricating layer 36 is easily peeled off due to mechanical force, and a part thereof is peeled off. Alternatively, since the vapor pressure or boiling point of the second lubricating layer 36 is relatively low, the second lubricating layer 36 may volatilize due to frictional heat during high rotation.

  In the characteristic 302 of the second comparative example (only the rust prevention layer 32 and the first lubricating layer 34), the torque coefficient K is excellent at a relatively high rotation, but the torque coefficient K is high at a relatively low rotation. It gets worse. For example, in the characteristic 302, the torque coefficient K at a relatively low rotation exceeds 0.13.

  On the other hand, the characteristic 304 (the antirust layer 32, the first lubricating layer 34, and the second lubricating layer 36) of the present embodiment is excellent in that the torque coefficient K is low overall from the low rotation region to the high rotation region. In the characteristic 304, the torque coefficient K is suppressed to a range of 0.10 to 0.12, for example.

  In the present embodiment, the torque coefficient K is low even in the high rotation region even though the second lubricating layer 36 exists on the surface of the bolt 16 or the nut 18. The reason for this is considered to be that a part of the first lubricating layer 34 is acting in a state where a part of the second lubricating layer 36 disappears at a relatively high rotation for the same reason as in the first comparative example. .

[A5. Effects in this embodiment]
According to this embodiment as described above, the torque coefficient K at the first rotational speed N1 (> N2) is made lower by the first lubricating layer 34 than the torque coefficient K at the second rotational speed N2 (FIG. 5). Further, the torque coefficient K at the second rotational speed N2 is made lower by the second lubricating layer 36 than the torque coefficient K at the first rotational speed N1 (FIG. 5). For this reason, it is possible to keep the torque coefficient K low during both high-speed rotation and low-speed rotation.

  Therefore, the first bolt 16a (first fastening member) and the second bolt 16b (second fastening member) are fastened by the electric tool 12 (first rotating tool) and the ratchet 13 (second rotating tool) having different rotational speeds N. In this case, the torque coefficient K of the first bolt 16a and the second bolt 16b can be made closer. Therefore, a stable axial force Ff can be obtained regardless of the tightening method.

  Further, even when the rotational speed N is different, the variation in the torque coefficient K is reduced (FIG. 5). For this reason, it is possible to simplify the confirmation process or the test process due to the variation in the torque coefficient K to reduce the man-hours of the operator 200 or to reduce the size of the electric tool 12 and the ratchet 13.

  This is not limited to the case where the first bolt 16a and the second bolt 16b have the same specifications (nominal diameter d, length, etc.), and the same applies to different specifications. That is, as described above, Ff = T / (K · d) holds. However, the torque coefficient K changes under the influence of the rotational speed N. For this reason, in order to generate the desired axial force Ff, it is necessary to consider the change of the torque coefficient K according to the rotational speed N. However, in order to perform such consideration, a lot of man-hours and costs are required. .

  The bolt 16 and the nut 18 of the present embodiment have the second lubricating layer 36 in addition to the rust prevention layer 32 and the first lubricating layer 34, thereby reducing the change in the torque coefficient K according to the rotational speed N (FIG. 5). For this reason, in the above formula (Ff = T / (K · d)), the torque coefficient K can be regarded as constant regardless of the rotational speed N, so that the above-mentioned man-hours and costs can be reduced. It becomes.

  Further, since there is a change in the torque coefficient K, a margin may be reflected in the tightening torque T when it is uncertain whether or not the necessary axial force Ff is secured. In order to increase the margin, it is necessary to increase the tightening torque T, and accordingly, the electric tool 12 and the ratchet 13 must be able to output a high torque. As described above, in this embodiment, since the change in the torque coefficient K due to the rotational speed N is small, the margin can be reduced. Accordingly, it is possible to prevent the electric tool 12 and the ratchet 13 from being increased in torque (in other words, increased in size).

  In this embodiment, the electric tool 12 (first rotating tool) and the manual ratchet 13 (second rotating tool) are used (FIG. 1). Moreover, the 1st rotation speed N1 is any value of 200-8000 rpm, and the 2nd rotation speed N2 is any value of 1-30 rpm (FIG. 4). As a result, in both cases where the first bolt 16a is fastened using the electric tool 12 and where the second bolt 16b is fastened using the ratchet 13, the influence of the rotational speed N on the torque coefficient K is reduced. In this state, a stable axial force Ff can be obtained.

  In this embodiment, when the first bolt 16a (first fastening member) is fastened with the electric tool 12 (first rotating tool) at the first rotational speed N1, the torque coefficient K (first) of the first bolt 16a is fastened. 1 torque coefficient K1) and the torque coefficient K (2) of the second bolt 16b when the second bolt 16b (second fastening member) is fastened by the ratchet 13 (second rotary tool) rotated at the second rotational speed N2. The difference from the second torque coefficient K2) is within 0.02 (predetermined range) (FIG. 5). Thereby, even when the first bolt 16a and the second bolt 16b are fastened by the electric tool 12 and the ratchet 13 having different rotational speeds N, the range of the difference between the first torque coefficient K1 and the second torque coefficient K2 is limited. Thus, a stable axial force Ff can be obtained.

  In the present embodiment, the workpiece 100 is a vehicle suspension arm (FIG. 1). This makes it easier to maintain a suitable fastening even in a suspension arm to which a relatively large load is frequently applied.

B. Modifications It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various configurations can be adopted based on the description of the present specification. For example, the following configuration can be adopted.

[B1. Applicable to]
In the above-described embodiment, the example in which the fastening system 10 is applied to the manufacture of a vehicle (fixing of the workpiece 100 as a suspension arm) has been described (FIG. 1). However, for example, if attention is paid to the use of the bolt 16 and / or the nut 18 having the structure of FIG.

[B2. Configuration of Fastening System 10]
(B2-1. First rotary tool and second rotary tool)
In the said embodiment, the fastening system 10 had the electric tool 12, the manual ratchet 13, and the manual torque wrench 14 (FIG. 1). However, for example, from the viewpoint of fastening the first bolt 16a and the second bolt 16b at different rotational speeds N, the present invention is not limited to this. For example, the first bolt 16a may be fastened by an impact driver (first electric tool), and the second bolt 16b may be fastened by a nut runner (second electric tool). Further, if the electric tool 12 has a function of adjusting the rotational speed N, the first bolt 16a is fastened at the first rotational speed N1 and the second bolt 16b at the second rotational speed N2 by the single electric tool 12. It is also possible to conclude. Further, the torque wrench 14 may be omitted.

  In the said embodiment, the ratchet 13 was used as a manual tool (2nd rotary tool) (FIG. 1). However, for example, from the viewpoint of fastening the first bolt 16a and the second bolt 16b at different rotational speeds N, the present invention is not limited to this. For example, the present invention can be applied to a screwdriver (screw driver) as a manual tool.

(B2-2. First fastening member and second fastening member)
In the above embodiment, the bolt 16 (the first bolt 16a and the second bolt 16b) is the target to be rotated by the rotary tool (FIG. 4). However, for example, from the viewpoint of fastening the first fastening member and the second fastening member at different rotational speeds N, the present invention is not limited to this. For example, the nut 18 (the first nut 18a and the second nut 18b) can be a rotation target.

  In the said embodiment, the volt | bolt 16 and the nut 18 each assumed the independent component (FIG. 1). However, for example, from the viewpoint of fastening the first fastening member and the second fastening member at different rotational speeds N, the present invention is not limited to this. For example, the bolt 16 and / or the nut 18 can be a part of a component (such as an engine). For example, a screw hole formed in the engine housing may be used as the nut 18.

  In the above embodiment, both the bolt 16 and the nut 18 have the structure shown in FIG. 2 (the antirust layer 32, the first lubricating layer 34, and the second lubricating layer 36). However, for example, from the viewpoint of reducing the difference in torque coefficient K at different rotational speeds N, the present invention is not limited to this. For example, only one of the bolt 16 and the nut 18 may have the structure shown in FIG.

  In the said embodiment, the antirust layer 32 contained the binder 40 and the metal flake 42 (FIG. 2). However, for example, from the viewpoint of rust prevention performance, it is not limited to this. For example, the rust prevention layer 32 can also be formed by a plating process.

  In the above embodiment, the first lubricant layer 34 includes the first lubricant 44, the synthetic resin 46, and the colorant 48 (FIG. 2). However, for example, from the viewpoint of reducing the torque coefficient K during high rotation (for example, 0.12 or less), the present invention is not limited to this. For example, the first lubricating layer 34 may be configured without the colorant 48. Alternatively, when the synthetic resin 46 itself has a certain level of lubricity, the synthetic resin 46 may also serve as the first lubricant 44.

  In the said embodiment, the 2nd lubricating layer 36 presupposed that it is comprised from a single raw material (FIG. 2). However, for example, from the viewpoint of reducing the torque coefficient K during low rotation (for example, 0.12 or less), the present invention is not limited to this. For example, the second lubricating layer 36 may include a colorant 48.

  In the said embodiment, the volt | bolt 16 and the nut 18 had the antirust layer 32, the 1st lubricating layer 34, and the 2nd lubricating layer 36 (FIG. 2). However, for example, if attention is paid to the function of the first lubricating layer 34 and the second lubricating layer 36 for reducing the difference in the torque coefficient K at different rotational speeds N, the antirust layer 32 can be omitted.

  In the above embodiment, it is assumed that both the first lubricating layer 34 and the second lubricating layer 36 are solid (FIG. 2). However, for example, if attention is paid to the functions of the first lubricating layer 34 and the second lubricating layer 36 for reducing the difference in the torque coefficient K at different rotational speeds N, the present invention is not limited to this. For example, the second lubricating layer 36 may be liquid, gel, or paste.

(B2-3. Others)
In the said embodiment, the fastening with the volt | bolt 16 (1st volt | bolt 16a and 2nd volt | bolt 16b) was performed about the 1st site | part 102 and the 2nd site | part 104 of the single workpiece | work 100 (refer FIG. 1). However, for example, from the viewpoint of fastening a plurality of bolts 16 or nuts 18 having the structure shown in FIG. 2 (rust prevention layer 32, first lubricating layer 34, and second lubricating layer 36) at different rotational speeds N, Not limited to.

  For example, the first bolt 16a can be used for the first workpiece, and the second bolt 16b can be used for a second workpiece different from the first workpiece. In this case, the first workpiece 16 is fixed by rotating the first bolt 16a at the first rotation speed N1 by the electric tool 12 (first rotation tool). Further, the second workpiece 16 is fixed by rotating the second bolt 16b at the second rotational speed N2 (<N1) by the ratchet 13 (second rotary tool). Note that the first workpiece and the second workpiece may be operated in the same facility, or may be operated in different facilities.

12 ... Electric tool (first rotating tool)
13 ... Manual ratchet wrench (second rotary tool)
16a ... 1st bolt (1st fastening member) 16b ... 2nd bolt (2nd fastening member)
DESCRIPTION OF SYMBOLS 30 ... Base material 32 ... Rust prevention layer 34 ... 1st lubrication layer 36 ... 2nd lubrication layer 44 ... 1st lubricant 46 ... Synthetic resin 100 ... Workpiece | work 102 ... 1st site | part 104 ... 2nd site | part N1 ... 1st rotational speed N2 ... second rotation speed K1 ... first torque coefficient K2 ... second torque coefficient

Claims (8)

A first fastening step in which the first fastening member is rotated at the first rotational speed by the first rotating tool to fix the first portion of the workpiece; and the second fastening member is lower than the first rotating tool by the second rotating tool. A fastening method including a second fastening step of rotating at a second rotational speed to fix the second part of the workpiece,
The first fastening member and the second fastening member are:
A metal substrate;
A rust preventive layer formed on the substrate;
A first lubricating layer formed on the rust preventive layer, including a first friction coefficient stabilizer that lowers the torque coefficient at the first rotational speed than the torque coefficient at the second rotational speed;
A second friction coefficient stabilizer that lowers the torque coefficient at the second rotation speed than the torque coefficient at the first rotation speed, and a second lubrication layer formed on the first lubrication layer. The fastening method characterized by this. The fastening method according to claim 1,
The first rotary tool is a power tool;
The second rotary tool is a manual tool;
The first rotation speed is any value of 200 to 8000 rotations per minute,
The second rotation speed is any value of 1 to 30 rotations per minute. In the fastening method according to claim 1 or 2,
The first friction coefficient stabilizer includes a first lubricant and a synthetic resin,
The second coefficient of friction stabilizer includes a second lubricant,
The first lubricant is colloidal silica,
The synthetic resin is an acrylic resin, a methacrylic resin, an epoxy resin, a phenol resin or a ketone resin,
The fastening method, wherein the second lubricant is a water-soluble plastic working oil or a water-soluble wax. In the fastening method according to any one of claims 1 to 3,
A torque coefficient of the first fastening member when the first fastening member is fastened by being rotated at the first rotational speed by the first rotary tool is defined as a first torque coefficient, and the second torque is obtained by the second rotary tool. When a torque coefficient of the second fastening member when the second fastening member is fastened by rotating at a rotational speed is defined as a second torque coefficient, a difference between the first torque coefficient and the second torque coefficient is predetermined. A fastening method characterized by being within a range. In the fastening method according to any one of claims 1 to 4,
The fastening method according to claim 1, wherein the workpiece is a vehicle suspension arm. A metal base, a rust preventive layer formed on the base, a first lubricant layer formed on the rust preventive layer, and a second lubricant layer formed on the first lubricant layer; A method of manufacturing a fastening member having
The manufacturing method includes:
A rust preventive layer forming step of forming a rust preventive layer by applying and drying a rust preventive agent on the substrate;
A first coefficient of friction stabilization that lowers the torque coefficient when the fastening member is fastened at a first rotational speed higher than the second rotational speed than the torque coefficient when the fastening member is fastened at a second rotational speed. A first lubricating layer forming step in which an agent is applied onto the rust preventive layer and dried to form the first lubricating layer;
A second friction coefficient stabilizer that lowers the torque coefficient at the second rotational speed than the torque coefficient at the first rotational speed is applied to the first lubricating layer to form the second lubricating layer. And a lubricating layer forming step. The manufacturing method according to claim 6,
The first friction coefficient stabilizer includes a first lubricant and a synthetic resin,
The second coefficient of friction stabilizer includes a second lubricant,
The first lubricant is colloidal silica,
The synthetic resin is an acrylic resin, a methacrylic resin, an epoxy resin, a phenol resin or a ketone resin,
The manufacturing method, wherein the second lubricant is a water-soluble plastic working oil or a water-soluble wax. A metal substrate;
A rust preventive layer formed on the substrate;
A first friction coefficient stabilizer that lowers the torque coefficient when engaged at a first rotational speed higher than the second rotational speed than the torque coefficient when engaged at a second rotational speed; A first lubricating layer formed on the rust layer;
A second friction coefficient stabilizer that lowers the torque coefficient at the second rotation speed than the torque coefficient at the first rotation speed, and a second lubrication layer formed on the first lubrication layer. A fastening member characterized by the above.

Images