JP2014088882A - Coil-spring built-in screw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coil-spring built-in screw capable of resiliently fixing a member to be fastened to a mating member.SOLUTION: This invention is constituted such that: an upper end winding 6 of a coil spring 8 is positioned between the seat surface of a screw head part 2 and an engaging ring 5 arranged at a non-screw shaft part 3; this upper end winding 6 is double-wound and divided into an upper side upper end winding part 6a and a lower side upper end winding part 6b; and the upper side upper end winding part 6a is positioned between the seat surface and the engaging ring 5, and the lower side upper end winding 6b is positioned below the engaging ring 5 to cause the coil spring 8 to be flexed in a range from the lower side upper end winding part 6b to the extremity end. With this constitution, if a flexing amount against a prescribed load is calculated in advance to calculate a screwing height of a coil-spring built-in screw 1, a mere screwing action of the coil-spring built-in screw 1 into its screwing height enables the coil-spring 8 to add the accurate calculated load to a member 9 to be fastened and resiliently fix the member to a mating member 10.

Description

  The present invention relates to a coil spring built-in screw capable of elastically fixing a fastened member to a mating member.

  Conventionally, when a fastened member such as an electronic component or a precision part is attached to a mating member, the fastened member is elastically fixed to the mating member as necessary. As an example of the member to be fastened, there is a heat sink of a liquid crystal television. Since this heat sink changes its amount of heat when it is deformed even a little, the elastic force of a coil spring is used to fix it. In addition, as another example, there is a fastened member attached so as to be able to move the gap from the seat surface to the mating member along the shaft portion of the screw. In order to prevent rattling, the elastic force of a coil spring incorporated in the screw is used. When fixing this type of fastened member, in addition to improving the efficiency of the assembly work, in order to prevent forgetting to attach the coil spring during the assembly work and to prevent it from falling off, including the component mounting screw member described in Patent Document 1, Various coil spring built-in screws are used. As shown in FIG. 5, this type of coil spring built-in screw 51 includes, as a basic structure, a screw head 52, a screwless shaft portion 53, a screw portion 54 having a smaller diameter than the screwless shaft portion 53, and the screw head. A locking ring 55 provided on the screwless shaft portion 53 at a predetermined interval from the seating surface of the portion 52, and a coil spring 58 having an upper end winding portion 56 and a tip end winding portion 57. The upper end winding portion 56 of the coil spring 58 is disposed between the seat surface of the screw head 52 and the locking ring 55, and the portion following the upper end winding portion 56 rides on the locking ring 55. ing. As a result, the coil spring 58 is locked to the locking ring 55 and is configured not to fall off the screwless shaft portion 53. Further, the coil spring 58 extends so as to cover the screwless shaft portion 53, and the tip end winding portion 57 presses the fastened member 59 at the tip thereof so that it can be elastically fixed to the mating member 60. Has been.

JP 2003-343533 A

  In the coil spring built-in screw 51, in order to obtain a predetermined load in advance, the deflection amount is calculated on the assumption that the coil spring 58 extending from the upper end winding portion 56 is uniformly bent over the entire length, and the screw is screwed until this deflection amount is obtained. The part 54 is screwed into the mating member 60. As a result, the above-described fastened member 59 is elastically fixed with a predetermined load, and predetermined fixing purposes such as prevention of deformation of the fastened member at the time of fixing and prevention of rattling of the fastened member attached in a movable manner are achieved. ing. However, with this coil spring built-in screw 51, even if the screw portion 54 is screwed into the mating member 60 until the tip end winding portion 57 of the coil spring 58 presses against the member 59 to be fastened, Since the riding portion is in contact with the locking ring 55, it cannot move smoothly, and the coil spring 58 does not bend from the riding portion to the upper end winding portion 56. In addition, the climbing portion of the coil spring 58 is not a constant position that varies depending on the situation when the coil spring 58 is mounted. For this reason, a predetermined load cannot be obtained with the amount of deflection calculated on the assumption of uniform deflection over the entire length of the coil spring 58, and there is no method of calculating an accurate load because the riding portion of the coil spring 58 cannot be specified. When an accurate load is required, there is a problem that the coil spring built-in screw 51 cannot be used.

  An object of the present invention is to eliminate the above-mentioned problem, and to provide a coil spring built-in screw capable of elastically fixing a member to be fastened by accurately applying a predetermined load.

  In order to achieve the above object, the present invention includes a screw head, a screwless shaft portion, and a screw portion, and the screwless shaft portion is provided with a locking portion at a predetermined interval from the seat surface of the screw head. A coil spring built-in screw for locking the coil spring by positioning the upper end winding portion of the coil spring between the seat surface and the locking portion, and the upper end winding portion of the coil spring is formed in a plurality of turns. The upper upper end winding portion and the lower upper end winding portion are divided into two, the upper upper end winding portion is positioned between the seat surface and the locking portion, and the lower upper end winding portion is engaged with the engagement. It is characterized in that the coil spring is configured to bend from the lower upper end winding portion to the tip, being positioned below the stop portion. According to this configuration, when the screw portion is screwed into the mating member, the coil spring comes into contact with the fastened member and starts to bend, and the elastic force of the coil spring starts to press the fastened member. When this threaded portion is further screwed in, the lower upper end winding portion of the coil spring is in contact with the locking portion, so there is no bending from the lower upper end winding portion to the upper upper end winding portion, and the coil Only the lower upper end winding portion of the spring is bent uniformly from the tip. Therefore, if the amount of deflection for a given load is calculated in advance and the screwing height is calculated, the coil spring will apply the calculated load to the fastened member simply by screwing the screw part so that the screwing height is reached. In addition, the member to be fastened can be elastically fixed to the counterpart member, and the coil spring built-in screw can be used even when an accurate load is required.

  Particularly, in order to easily incorporate the coil spring into the unthreaded shaft portion, it is desirable that the upper end seat winding portion of the coil spring has two turns.

  In addition, when manufacturing a coil spring built-in screw by incorporating a coil spring, it is not necessary to align the direction of the coil spring, and in order to increase the manufacturing efficiency of the coil spring built-in screw, It is desirable to form the winding portion into a plurality of windings of the same number as that of the upper end winding portion.

  According to the present invention described above, a coil spring built-in screw capable of calculating the amount of deflection of a coil spring corresponding to a predetermined load, applying the calculated load to a member to be fastened, and elastically fixing the load is provided. be able to.

The front view of the coiled spring built-in screw which concerns on embodiment of this invention. The front view before the assembly of the coil spring which concerns on embodiment of this invention. Explanatory drawing which shows the principal part which shows the use condition of the coil spring built-in screw which concerns on embodiment of this invention. The front view before the assembly of the coil spring which concerns on the modification of embodiment of this invention. The principal part explanatory drawing which shows the use condition of the conventional coil spring built-in screw.

  Hereinafter, a coil spring built-in screw according to an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, a coil spring built-in screw 1 according to an embodiment of the present invention includes a screw head 2 having a drive hole 2 a to which rotation of a driver bit (not shown) is transmitted, and a screw head 2. A screwless shaft portion 3 extending from the center of the seat surface, a screw portion 4 having a diameter smaller than that of the screwless shaft portion 3, a locking ring 5 serving as a locking portion provided on the screwless shaft portion 3, and an upper end winding portion 6 and a coil spring 8 having a tip end winding portion 7. The locking ring 5 is located at a distance approximately equal to the wire diameter d of the coil spring 8 from a step 2b provided on the seat surface of the screw head 2, and an upper upper end seat to be described later is included in this distance. The winding part 6a is configured to be positionable. The outer diameter of the locking ring 5 is set to be larger than the center diameter D of the coil spring 8 and smaller than the outer diameter, and the upper upper end winding portion 6a can easily get over the locking ring 5 when the coil spring 8 is assembled. In addition, the coil spring 8 is configured to have a sufficient size to prevent the coil spring 8 from falling off. Further, the ring width t of the locking ring 5 is formed to have a dimension smaller than a width in which the coil spring 8 is manually pulled when the coil spring 8 is assembled and the upper end winding part 6 is divided into two, and is opened. The coil spring 8 is configured to be easily assembled. In addition, although the said latching | locking part is not shown in figure, the protrusion provided at predetermined intervals in the circumferential direction may be sufficient.

  The upper end seat winding portion 6 of the coil spring 8 is formed in two turns as shown in FIG. 2, and is divided into two parts above and below the locking ring 5 when the coil spring 8 is assembled into the screwless shaft portion 3. The upper upper end winding portion 6a and the lower upper end winding portion 6b are configured. The upper end winding portion 6 may be two or more turns, and the upper upper end winding portion 6a and the lower upper end winding portion 6b when the coil spring 8 is assembled in the case of two windings as compared to the case of three windings or more. Can be easily opened, and the coil spring 8 can be assembled more easily. Moreover, the front end winding part 7 of the said coil spring 8 is 1 turn, and it is comprised so that the to-be-fastened member 9 mentioned later can be pressed elastically.

  The coil spring 8 has a spring effective portion 8a connected between the lower upper end winding portion 6b and the tip end winding portion 7, and this spring effective portion 8a extends over almost the entire length of the screwless shaft portion 3. It is configured to have an effective winding number Na of about 3.5 turns. The spring effective portion 8a is configured to bend as the tip end winding portion 7 comes into contact with the fastened member 9, and the coil spring 8 has an elastic force. The coil spring 8 has an inner diameter slightly larger than the diameter of the screwless shaft portion 3, and the spring effective portion 8 a is configured to bend along the screwless shaft portion 3 without any trouble.

  An upper upper end winding portion 6 a of the coil spring 8 is located between the locking ring 5 provided on the screwless shaft portion 3 and the step portion 2 b, and is positioned below the locking ring 5. The locking ring 5 is sandwiched from the upper and lower directions together with the lower upper end winding portion 6b, and the coil spring 8 is configured not to fall off the screwless shaft portion 3. The lower upper end winding portion 6b of the coil spring 8 is in contact with the locking ring 5 over substantially the entire circumference and receives a load when the spring effective portion 8a is bent, and the coil spring is separated from the lower upper end winding portion. It is comprised so that it may bend to between front-end | tips. Thereby, the substantial spring length of the coil spring 8 is the length L0 from the lower upper end winding portion to the tip end winding portion, and the deflection amount of the coil spring 8 is the deflection amount of the spring effective portion 8a.

The strain amount δ with respect to the predetermined load P is calculated by the following equations 1 and 2.
P = kδ ............ Formula 1
(P: load, k: spring constant)
k = Gd ⁴ / 8NaD ³ ............ Formula 2
(G: transverse elastic modulus, d: wire diameter of coil spring, Na: effective number of turns,
D: Center diameter of coil spring)

  When the member 9 to be fastened is elastically fixed to the mating member 10 using the coil spring built-in screw 1 as shown in FIG. 3, a pilot hole in which the screwless shaft portion 3 is formed in the member 9 to be fastened. While being guided into 9a, the threaded portion 4 is screwed into the mating member 10 and thus screwed into the threaded portion 10a. Along with this, the tip end winding portion 7 of the coil spring 8 abuts on the fastened member 9, the spring effective portion 8 a of the coil spring 8 starts to bend, and the elastic force of the coil spring 8 starts to press the fastened member 9. . When the screw portion 4 is further screwed in, the lower upper end winding portion 6 b of the coil spring 8 is in contact with the locking ring 5, so that the locking ring 5 receives a load generated by the elastic force of the coil spring 8. At this time, since the locking ring 5 is located from the lower upper end winding portion 6b to the upper upper end winding portion 6a, it does not bend and the lower upper end winding portion 6b of the coil spring 8 is not bent. Only the spring effective portion 8a extending to the winding portion 7 is uniformly bent, and the coil spring 8 has a load length L1. Therefore, if the amount of deflection (δ: L0−L1) with respect to a predetermined load is calculated in advance and the screwing height of the coil spring built-in screw 1 is calculated, the screwed height obtained by calculating the coil spring built-in screw 1 is calculated. By simply screwing the threaded portion 4 so that the coiled spring 8 applies the calculated load to the fastened member 9, the fastened member 9 can be elastically fixed to the mating member 10.

  As a modification of the embodiment of the present invention, the gap between the stepped portion 2b provided on the seating surface of the screw head 2 and the locking ring 5 is not less than the wire diameter of the coil spring 8, and the upper end of the coil spring 8 The upper upper end winding portion 6a and the lower upper end winding portion 6b that form the end winding portion 6 may be divided in advance at intervals equal to or larger than the ring width of the locking ring 5. Further, as shown in FIG. 4, the tip end winding portion 7 of the coil spring 8 can be formed in a plurality of turns equal to the number of turns of the upper end end winding portion 6. In this case, when manufacturing the coil spring built-in screw (not shown) by incorporating the coil spring 8, it is not necessary to align the direction of the coil spring 8, so that the manufacturing efficiency of the coil spring built-in screw can be increased. it can. Further, the locking ring 5 can be formed without providing the stepped portion 2 b on the seating surface of the screw head 2.

  In addition, although embodiment of this invention was described, the specific structure of each part is not limited only to embodiment mentioned above, A various deformation | transformation is possible in the range which does not deviate from the meaning of this invention.

1 ... Screw with built-in coil spring
2 ... Screw head
3… Screw without shaft
4 ... Screw part
5 ... Lock ring
6 ... Upper end winding part
6a ... Upper upper end winding part
6b: Lower upper end winding part
8 ... Coil spring

Claims (3)

  A screw head, a screwless shaft portion, and a screw portion are provided, and a locking portion is provided on the screwless shaft portion at a predetermined interval from the seating surface of the screw head, and a coil is provided between the seating surface and the locking portion. A coil spring built-in screw that locks the coil spring by positioning the upper end winding portion of the spring, wherein the upper end winding portion of the coil spring is formed into a plurality of windings, which are formed as an upper upper end winding portion and a lower upper end The upper end end winding part is positioned between the seating surface and the locking part, and the lower upper end winding part is positioned below the locking part, and the coil spring is A coil spring built-in screw, characterized in that it is configured to bend between a lower upper end winding portion and a tip.   The coil spring built-in screw according to claim 1, wherein the upper end winding portion of the coil spring has two turns.   3. The coil spring built-in according to claim 1, wherein the tip end of the coil spring is a tip end winding portion, and the tip end winding portion is formed into a plurality of turns equal to the number of turns of the upper end end winding portion. screw.

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