WO2024225191A1 - Inner socket - Google Patents

Abstract

Provided is an inner socket that is capable of suppressing damage of a coating provided to a fastening member and stably fastening an object to be fastened by the fastening member. An inner socket according to an embodiment of the present invention can be mounted in a socket of an impact wrench, the inner socket comprising a wall part that defines a receiving port capable of receiving at least a part of the fastening member, and the wall part having a thickness of 2.0-6.0 mm.

Description

Inner socket

The present invention relates to an inner socket that can be attached to the socket of an impact wrench.

It is known that a coating is applied to the surface of fastening members such as bolts and nuts to improve corrosion resistance (see, for example, Patent Document 1). It is desirable to use an impact wrench to tighten such fastening members and to make the tightening work more efficient. However, when tightening fastening members that have a coating, sufficient care must be taken to prevent damage to the coating, and using an impact wrench may cause damage to the coating.

JP 2005-028802 A

The present invention was made to solve the above-mentioned problems in the past, and its main objective is to provide an inner socket that can suppress damage to the coating on the fastening member and can sufficiently tighten the fastening member.

[1] An inner socket according to an embodiment of the present invention is an inner socket that can be attached to a socket of an impact wrench. The inner socket has a wall portion that defines an opening capable of receiving at least a part of a fastening member. The wall portion has a thickness of 2.0 mm to 6.0 mm.
[2] In the inner socket described in [1] above, a groove may be formed in a corner of the receiving opening.
[3] In the inner socket described in [1] or [2] above, the receiving opening may be capable of receiving a nut as the fastening member.

According to an embodiment of the present invention, it is possible to realize an inner socket that can suppress damage to the coating on the fastening member and can sufficiently tighten the fastening member.

Fig. 1(a) is a schematic plan view of an inner socket according to one embodiment of the present invention, and Fig. 1(b) is a schematic side view of the inner socket shown in Fig. 1(a). FIG. 2 is a schematic perspective view of the inner socket shown in FIG. FIG. 3 is a schematic plan view of a socket in which the inner socket shown in FIG. FIG. 4 shows a state in which the inner socket shown in FIG. 1(a) is attached to a socket.

Below, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. Furthermore, in order to make the description clearer, the drawings may show the width, thickness, shape, etc. of each part more diagrammatically than the embodiments, but these are merely examples and do not limit the interpretation of the present invention.

A. Inner Socket Figure 1(a) is a schematic plan view of an inner socket according to one embodiment of the present invention; Figure 1(b) is a schematic side view of the inner socket shown in Figure 1(a); Figure 2 is a schematic perspective view of the inner socket shown in Figure 1(a).
The illustrated inner socket 1 can be attached to a socket 10 of an impact wrench (see FIG. 4). The inner socket 1 has a wall portion 22 that defines a receiving opening 2 capable of receiving at least a part of a fastening member. The thickness of the wall portion 22 is 2.0 mm to 6.0 mm, preferably 3.0 mm to 6.0 mm, more preferably 4.0 mm to 5.5 mm, and particularly preferably 4.5 mm to 5.5 mm.
According to this configuration, in the tightening operation of the fastening member, the inner socket receives at least a part of the fastening member while being attached to the socket of the impact wrench. In this state, the fastening member is tightened against another fastening member or a fastened object, thereby fastening two or more fastened objects. With this inner socket, even if the tightening operation of the fastening member is performed with an impact wrench, direct contact between the fastening member and the socket can be suppressed, and damage to the coating provided on the fastening member can be suppressed. Furthermore, since the thickness of the wall portion of the inner socket is within the above range, the fastening member can be sufficiently tightened in the tightening operation described above.

The inner socket 1 may have any suitable shape as long as it can be attached to the socket 10. The outer shape of the inner socket 1 is changed as appropriate according to the shape of the socket 10. The wall 22 of the inner socket 1 typically has a cylindrical shape extending in a predetermined direction. When viewed from the axial direction of the inner socket 1, the outer shape of the wall 22 has, for example, a polygonal shape, and preferably a hexagonal shape.

The receiving opening 2 may adopt any suitable shape as long as it can receive at least a part of the fastening member. As will be described in detail later, when the fastening member is a nut, the receiving opening 2 can receive (fit) the entire nut, and when the fastening member is a bolt, the receiving opening 2 can receive (fit) the head of the bolt. The receiving opening 2 may be a through hole that penetrates the inner socket 1 in a predetermined direction (the axial direction of the inner socket), or may be a recess that is recessed in a predetermined direction. The receiving opening 2 in the illustrated example is defined as an internal space of the wall portion 22, and penetrates the inner socket 1 in a predetermined direction. The shape of the receiving opening 2 is, for example, a polygonal shape, preferably a hexagonal shape, when viewed from the axial direction of the inner socket 1.
The size of the receiving port 2 may be changed arbitrarily and appropriately depending on the size of the fastening member used in the fastening operation.

A groove 21 is formed in the corner of the receptacle 2 (i.e., the inner surface of the wall portion 22). By forming a groove in the corner of the receptacle, stress concentration in the corner of the receptacle can be suppressed during the tightening operation of the fastening member, and damage to the inner socket can be reduced. Therefore, the fastening member can be tightened stably.
The grooves 21 are typically formed at all corners (vertices of the corners) of the receiving opening 2. The grooves 21 have, for example, an arc shape. The grooves 21 in the illustrated example have a substantially C-shape that opens toward the inside of the receiving opening 2 when viewed from the axial direction of the inner socket 1. The grooves 21 extend, for example, on the inner surface of the receiving opening 2 over the entire axial direction of the inner socket 1.
When the groove 21 is formed in the wall portion 22, the thickness of the wall portion 22 excluding the portion in which the groove 21 is formed is adjusted to fall within the above range.
When the groove 21 has a substantially C-shape when viewed from the axial direction of the inner socket 1, the radius of curvature of the groove 21 is, for example, 0.1 mm to 3.0 mm, and preferably 0.5 mm to 2.5 mm. The radius of curvature of the groove 21 having a substantially C-shape is preferably ½ or less of the thickness of the wall portion 22 (the plate thickness of the inner socket).

The dimension (height) of the wall portion 22 in the axial direction of the inner socket 1 is arbitrarily and appropriately adjusted according to the size of the fastening member received by the receiving port 2. In one embodiment, the height of the wall portion 22 is preferably within a range of about ±1 mm of the depth of the nut insertion portion of the socket 10 (representatively part number 10) of the impact wrench. The height of the wall portion 22 is, for example, 10 mm to 50 mm, and preferably 15 mm to 40 mm.

The inner socket 1 may further include a flange portion (not shown). When the inner socket includes a flange portion, axial movement of the inner socket relative to the socket of the impact wrench can be suppressed during the tightening operation of the fastening member.
The flange portion is provided on the outer surface of the wall portion 22. The flange portion typically extends outward from the wall portion 22 so as to surround the wall portion 22 when viewed in the axial direction of the inner socket 1. In one embodiment, the flange portion is joined to an end portion of the outer surface of the wall portion 22 in the axial direction.

The inner socket 1 is typically made of a resin material.
The elastic modulus of the resin material is preferably 1400 MPa to 2500 MPa. The elastic modulus is measured in accordance with, for example, ISO 527 GB/T 1040.
The tensile strength of the resin material is preferably 18 MPa to 70 MPa. The tensile strength is measured in accordance with, for example, ISO 527 GB/T 1040.
The resin material preferably has an elongation percentage of 1.0% to 14.0%. The elongation percentage is measured in accordance with, for example, ISO 527 GB/T 1040.
The flexural modulus of the resin material is preferably 2000 MPa to 3000 MPa. The flexural modulus is measured in accordance with, for example, ISO 178 GB/T 9341.
The resin material preferably has a bending strength of 40 MPa to 110 MPa, and the bending strength is measured in accordance with, for example, ISO 178 GB/T 9341.
The resin material preferably has a Shapy impact factor of 3.0 kJ/m ³ to 27.0 kJ/m ^3. The Shapy impact factor is measured in accordance with ISO 179 GB/T 1043, for example.
If the inner socket (i.e., the wall portion) is made of such a resin material, the fastening members can be tightened more stably when the tightening operation of the fastening members is carried out by an impact wrench.
The softening temperature of the resin material is, for example, 20°C to 260°C, and preferably 60°C to 120°C.

Such resin materials include, for example, polylactic acid; acrylonitrile-butadiene-styrene copolymer; and polycarbonate-based resins. The resin materials can be used alone or in combination. Among the resin materials, preferred are polylactic acid, acrylonitrile-butadiene-styrene copolymer, and polycarbonate-based resins. From the viewpoint of ease of molding, polylactic acid is more preferred. From the viewpoint of heat resistance, acrylonitrile-butadiene-styrene copolymer is more preferred.

Such an inner socket 1 can be typically manufactured by a three-dimensional additive manufacturing device (3D printer), and can be easily manufactured by a fused deposition modeling 3D printer, preferably. When the inner socket is manufactured by a fused deposition modeling 3D printer, the infill density of the wall portion can be suitably adjusted.
The infill density of the wall portion 22 is, for example, 40 volume % to 100 volume %, and preferably 50 volume % to 100 volume %. If the density of the wall portion of the inner socket is in this range, the fastening member can be tightened more stably.

B. Socket and Fastening Member As shown in Figures 3 and 4, the inner socket 1 can be attached (fitted) into the internal space of a socket 10 of an impact wrench. The impact wrench is typically an air impact wrench. The socket 10 is typically made of metal. The shape of the socket 10 is appropriately changed depending on the shape of the fastening member. The socket 10 in the illustrated example has a hexagonal internal space and can fasten a hexagonal nut and a hexagonal bolt.
The fastening member may be, for example, a nut or bolt, preferably a nut, and more preferably a hexagonal nut. The fastening member is provided with a coating. Examples of the coating include the damage-resistant coating described in JP-A-2005-28802 and the coating described in JP-A-2007-291280. The entire disclosures of these publications are incorporated herein by reference. The coating has a thickness of, for example, 30 μm or more.

The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples. The evaluation methods are as follows.

(1) Condition of the Coating In each of the Examples and Comparative Examples, after the hexagonal nut was fastened to the shank (threaded portion) of the bolt, the hexagonal nut and washer were removed from the bolt. The condition of the coating on each of the bolt, hexagonal nut and washer was then visually confirmed and evaluated according to the following criteria. The results are shown in Table 1.
○: All coatings on bolts, nuts and washers are intact.
×: Damage was observed in the coating of at least one of the bolts, nuts, and washers.

(2) Evaluation of tightening (measurement of axial force and return torque)
In each of the examples and comparative examples, the hexagonal nut was tightened onto the shank (threaded portion) of the bolt, and then the axial force and return torque generated in the shank of the bolt were measured using a simplified axial force. The results are shown in Table 1.

<Examples 1 to 6>
The inner socket shown in FIG. 1 is made of the resins shown in Table 1 (PLA: polylactic acid, ABS: acrylonitrile-butadiene-styrene copolymer, PC: polycarbonate resin) as the main components. Manufactured by a fused deposition model 3D printer (manufactured by CREALITY, product name ENDER-3).
The wall thickness and infill density of the inner socket are shown in Table 1.

Bolts, hexagonal nuts, and washers were also prepared. The bolt standard (JIS B 118 Appendix JA) was M20, and the bolt strength classification was 10.9. Each of the bolts, hexagonal nuts, and washers was coated with a fluororesin coating material (manufactured by Takenaka Seisakusho Co., Ltd., product name Takecoat 1000). The thickness of the coating was 30 μm or more and 65 μm or less.

A temporary fastener was prepared with a hole through which the shank (threaded portion) of the bolt could be inserted, and the temporary fastener was fixed in place using a vice. The shank of the bolt was then inserted into the hole in the temporary fastener. With the head of the bolt in contact with the temporary fastener, the free end of the shank (the end opposite the head) was protruding from the temporary fastener, and a washer was fitted onto the free end.

Next, a hexagonal nut was fitted into the receiving opening of the inner socket, and the hexagonal nut was tightened onto the free end of the shaft with an air impact wrench at a torque of 52 Nm.

<Comparative Example 1>
An inner socket was manufactured in the same manner as in Example 1, except that the thickness of the wall of the inner socket was changed to 8.5 mm, and an attempt was made to tighten a hexagonal nut onto the free end of the shaft using the inner socket. However, the inner socket was deformed, and the hexagonal nut could not be sufficiently tightened.

<Comparative Example 2>
Except for not using an inner socket, the hexagonal nut was tightened onto the free end of the shaft in the same manner as in Example 1. When tightening the hexagonal nut, the hexagonal nut was in direct contact with the socket of the air impact wrench.

[evaluation]
As is clear from Table 1, by using an inner socket having a wall thickness within the above range, it is possible to stably tighten the nut with an impact wrench while suppressing damage to the coatings of the bolt, nut and washer (especially the coating of the nut).

<Examples 7 to 12>
The inner socket shown in FIG. 1 was manufactured by a fused deposition model 3D printer (manufactured by CREALITY, product name ENDER-3) so that ABS (acrylonitrile butadiene styrene copolymer) was the main component. The softening temperature of ABS was 100 ° C. or higher.
Table 2 shows the outer dimension A (see FIG. 1), inner dimension B (see FIG. 1), wall thickness, radius of curvature of the groove, and height of the inner socket.

In addition, a plurality of sets of bolts, hexagonal nuts, and washers were prepared. Each of the bolts, hexagonal nuts, and washers was coated with a fluororesin coating material (manufactured by Takenaka Seisakusho Co., Ltd., product name Takecoat 1000). The thickness of the coating was 30 μm or more and 65 μm or less.
The strength class of the bolt is 10.9, the tensile strength is 1040 N/ ^mm2 or more, the Vickers hardness Hv is 320 to 380, the 0.2% yield strength is 940 N/ ^mm2 or more, and the proof load is 830 N/ ^mm2 .
The bolt specifications (JIS B 118 Appendix JA), axial force P for the proof load, torque coefficient k, outer diameter d, torque Ts for the proof load, and effective cross-sectional area As are shown in Table 3. The bolt proof load and torque coefficient k were measured in advance.

A temporary fastener was prepared with a hole through which the shank (threaded portion) of the bolt could be inserted, and the temporary fastener was fixed in place using a vice. The shank of the bolt was then inserted into the hole in the temporary fastener. With the head of the bolt in contact with the temporary fastener, the free end of the shank (the end opposite the head) was sticking out from the temporary fastener, and a washer and a hexagonal nut were then fitted onto the free end.

Next, a hexagonal nut was fitted into the receiving opening of the inner socket, and a torque tester (manufactured by JFE Advantec, maximum axial force: 800 kN, maximum torque: 5000 Nm) was used to gradually apply torque to the nut through the inner socket. This allowed the nut to be tightened onto the free end of the shank, and the axial force generated in the shank of the bolt was measured. Thereafter, application of torque to the nut was terminated when the bolt's proof load was reached, or when the torque and axial force decreased due to the destruction of the inner socket.
Next, the torque (unit: Nm) applied to the nut was plotted on the horizontal axis against the measured axial force (unit: kN) on the vertical axis to create a torque-axial force diagram. From the torque-axial force diagram, the torque and axial force when the torque was at its maximum, and the torque and axial force when the axial force was at its maximum were determined. The axial force when the torque was at its maximum was taken as the ultimate strength LS of the inner socket.
The calculation of the ultimate strength of the inner socket was repeated three times for each embodiment. The results are shown in Table 4.

<Example 13>
An inner socket was manufactured in the same manner as in Example 12, except that the main component of the inner socket was changed to PLA, and the ultimate strength of the inner socket was derived.

[evaluation]
The proof load of a bolt with strength class 4.8 is 310 N/ ^mm2 , which is 37.3% (=310/830×100) of the proof load of a bolt with strength class 10.9 (830 N/ ^mm2 ). This ratio of the proof load of a bolt with strength class 4.8 to the proof load of a bolt with strength class 10.9 (hereinafter referred to as the standard ratio) can be a standard for evaluating the yield strength of normal bolts.
As is clear from Table 4, in Examples 7 to 13, the ratio of the ultimate strength of the inner socket to the proof load (specifically, axial force P) of the bolt with strength class 10.9 exceeds the reference ratio. Therefore, it is presumed that the inner socket has sufficient strength for a normal bolt.
Therefore, it can be seen that by using an inner socket when tightening fastening members, the bolt and/or nut can be tightened stably while preventing damage to the coatings on the bolt, nut and washer.

The inner socket according to the embodiment of the present invention can be suitably used for tightening fastening members generated in the manufacture of various industrial products.

1 Inner socket 2 Receptacle 21 Groove 22 Wall portion

Claims (3)

An inner socket that can be attached to a socket of an impact wrench,
a wall portion defining an opening capable of receiving at least a portion of a fastener;
The inner socket has a wall thickness of 2.0 mm to 6.0 mm. The inner socket of claim 1, wherein a groove is formed in the corner of the receiving opening. The inner socket according to claim 1 or 2, wherein the receiving opening is capable of receiving a nut as the fastening member.

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