JP2005155818A - Head screw with captive washer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fastening structure capable of surely fixing a planar fastened body and being thinned. <P>SOLUTION: This head screw with captive washer 10 is composed of a head screw 11, a spring lock washer 12 and a flat washer 13. As an outer diameter 11d of a cylindrical part 11c from a bearing surface 11a of the head screw 11 to an incomplete screw part 11b is determined to be smaller than a trough diameter 11e of the screw, the cylindrical part 11c is entered into a female screw, and completely fastened up regardless of a thickness of the fastened body. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a washer-incorporating machine screw that can securely fix a thin plate-like body to be fastened, such as a terminal board, and a fastening structure using the same.

  The washer built-in machine screw used to fix the equipment grounding terminal and power supply terminal will be described. In FIG. 3, the length of the cylindrical portion 31c from the seating surface 31a of the small screw 31 to the incomplete screw portion 31b is larger than the total thickness of the spring washer 32 and the flat washer 33, and the diameter 31d of the cylindrical portion 31c is the screw It is almost equal to the effective diameter and is set larger than the thread root diameter 31e.

  For this reason, when the fastened body 41 on the thin plate is screwed to the fastening body 42, the cylindrical portion 31 c of the washer-incorporating machine screw 30 interferes with the female screw 43 provided on the fastening body 42 and does not enter the female screw 43. A gap 44 is formed between the fastening portions by the difference between the length of the cylindrical portion 31c of the screw 31 and the thickness of the washer, and the fastening body 41 cannot be reliably fixed.

  In particular, when a power terminal such as a power terminal is not completely fixed, the contact state becomes unstable, and heat may be generated when a large current flows there. For this reason, when the thickness of a to-be-fastened body is smaller (thin) than the difference mentioned above, the female screw opening part of the fastening body was chamfered more than a difference.

In recent years, thinning of equipment has been required, and when trying to fix a thin plate terminal to a thin part such as a housing, chamfering is required at the female screw opening, and the number of effective threads is reduced at the thin part. However, it was not possible to fasten with the same fastening force, and a thin plate-like body to be fastened was fastened with a small screw whose incomplete thread portion was shortened. (For example, see Patent Document 1)
JP-A-53-99157

  The problem to be solved is that a thin plate-like body such as a round terminal cannot be securely screwed to the fastening body and the fastening structure cannot be thinned while further thinning of the device is required. It is.

  If the fastening body has sufficient thickness as in the conventional case, the screw strength can be secured even if chamfering more than the gap, but if the chamfering is applied to the opening of the female thread in addition to making the fastening body thinner, the number of effective threads When the bolts were tightened with the same fastening force, the thread could be damaged.

  An object of this invention is to provide the fastening structure which can fix a plate-shaped to-be-fastened body reliably and can be reduced in thickness.

  In order to solve the above problems, the present invention relates to a washer-embedded machine screw in which a washer such as a spring washer or a plain washer is incorporated in a machine screw, and the machine screw is located outside the cylindrical part from the seat surface to the incomplete screw part. The diameter is set smaller than the root diameter of the screw.

  Moreover, it is the fastening structure which fixes a plate-shaped to-be-fastened body to an apparatus using this washer built-in machine screw.

  In the washer-incorporating machine screw of the present invention, the outer diameter of the cylindrical portion is set to be smaller than the root diameter of the screw, so that the thin plate-like body to be fastened can be securely screwed to the fastening body. Further, since it is not necessary to provide chamfering at the opening of the female screw and the number of effective threads can be secured, the fastening structure can be made thinner.

  In addition, it is possible to reduce the thickness of the connection structure of the power unit for connecting the ground wire, the power supply lead wire, and the like, and ensure a good contact state.

  The machine screw is a machine screw with a built-in washer in which the outer diameter of the cylindrical part from the seat surface to the incomplete thread part is set smaller than the root diameter of the screw, and a washer such as a spring washer or plain washer is incorporated in the machine screw. .

  In FIG. 1, a machine screw 10 with a built-in washer is composed of a machine screw 11, a spring washer 12, and a washer 13 and a cylindrical part 11c from a seat surface 11a of the machine screw 11 to an incomplete thread part 11b. The outer diameter 11d is set smaller than the thread valley diameter 11e.

  Usually, when the spring washer 12 is compressed, it is set to about 1 mm from the lower surface of the flat washer 13 to the incomplete threaded portion 11b. It was necessary to provide a chamfer of 0.6 mm or more at the opening of the female screw provided on the body.

  However, in the small screw 11 of the present invention, the outer diameter 11d of the cylindrical portion 11c is set smaller than the root diameter 11e of the screw, so that the cylindrical portion 11c can enter the female screw and can be tightened to the end.

  In FIG. 2, a power supply lead wire 22 (or ground wire) is fixed by caulking to the outer peripheral portion of a thin round terminal 21 which is a body to be fastened, and a washer is incorporated in a fastening body 23 for fixing the round terminal 21. A female screw 24 that is screwed into the machine screw 10 is provided.

  When the round terminal 21 is fixed to the fastening body 23 with the washer-incorporated machine screw 10, the outer diameter 11d of the cylindrical portion is smaller than the mountain diameter of the female screw 24. Therefore, when the machine screw 11 is tightened, the cylindrical portion 11c is It goes into the inside of 24.

  For this reason, it is not necessary to provide a chamfer at the opening of the female screw 24, and even with the thin fastening body 23, the number of effective threads can be secured, and secure screw fixing can be achieved only by ordinary screw machining.

  As described above, regardless of the thickness 21 a of the round terminal 21, the spring washer 12 and the flat washer 13 can be fixed to the fastening body 23 in a state where the spring washer 12 and the round washer 21 are reliably in contact with each other.

  In the first embodiment, two spring washers and flat washers have been described. However, the present invention is not limited to the shape and number of washers, and the number of washers may be one. Moreover, a to-be-fastened body is not limited to electric power parts, such as a power supply terminal, It can be used also for the same screw fastening structure as the past.

  The washer-incorporating machine screw of the present invention is useful for reducing the thickness of the fastening structure because the thin plate terminal can be securely screwed without chamfering the opening of the female screw.

Structural drawing of a machine screw incorporated with a washer in Embodiment 1 of the present invention Explanatory drawing of the fastening structure in Example 1 of this invention Explanatory drawing of fastening structure using conventional general washer built-in machine screw

Explanation of symbols

10 Machine Screws with Built-in Washers 11 Machine Screws 11a Seat Surface 11b Incomplete Screw Part 11c Cylindrical Part 11d Outer Diameter 11e Valley Diameter 12 Spring Washer 13 Plain Washer 21 Round Terminal (Fastened Body)
22 Power supply lead wire (or ground wire)
23 Fastening body 24 Female thread

Claims (3)

In the washer built-in machine screw in which a washer such as a spring washer or a flat washer washer was incorporated in the machine screw, the outside diameter of the cylindrical part from the seat surface to the incomplete thread part was set smaller than the root diameter of the screw. A machine screw with a built-in washer. A fastening structure in which a thin plate-like body to be fastened, such as a ground terminal or a power supply terminal, is fixed to a device with the machine screw with a washer according to claim 1. A motor or a motor control device using the fastening structure according to claim 2.