JPH0589922U - Frame connection structure - Google Patents

Abstract

(57) [Summary] [Purpose] Even with synthetic resin frames having the same shape but different hardness, parts can be joined at low cost without damaging the screwing boss. [Structure] A boss 2 is integrally formed on a frame 1 made of a hard synthetic resin.
Is provided upright, and the boss 2 is provided with a pilot hole 3 for a screw. The component 4 is brought into contact with the tip portion of the boss, the first self-tapping screw 5 penetrates the through hole 4a, and the component 4 and the frame 1 are coupled by screwing. The portion of the prepared hole 3 near the tip is a large diameter hole 3b. At the recessed position of the large diameter hole 3b, a small diameter hole 3c is provided following the large diameter hole. In the case of the frame 1 made of hard synthetic resin, the short first self-tapping screw 5 is selected and coupled by the large diameter hole 3b with a small screwing amount, and in the case of the frame 11 made of soft synthetic resin, the long self-tapping screw 5 is selected. Two self-tapping screws 15 are selected and joined by a small diameter hole 13c having a large screwing amount.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a joint structure of a frame in which other parts are screwed and fixed to a frame made of synthetic resin such as a watch frame.

[0002]

[Prior Art]

 In order to attach and fix other parts to a frame made of synthetic resin such as a watch frame at a predetermined distance from this frame, a coupling structure as shown in FIG. 3 is generally adopted. That is, the boss 22 is integrally erected at a predetermined height inside the frame 21, and the through hole 24a of the component 24 to be attached is aligned with the prepared hole 23 provided in the boss. The tap screw 25 is inserted into the prepared hole 23, and the prepared hole is screwed and tightened to join the component 24 to the tip of the boss 22.

[0003]

[Problems to be solved by the device]

 As mentioned above, when screwing the self-tapping screw into the pilot hole of the boss, the screw thread pushes through the inner diameter of the pilot hole while forcing the thread, so if the pilot hole diameter is small, tighten the screw. A large stress is generated due to, and may damage the boss. This tendency is more remarkable in the case of a hard synthetic resin frame. On the other hand, if the diameter of the pilot hole is made large, the amount of screwing becomes small, so the tightening force and pullout drag force become small, which causes a decrease in bond strength. This tendency is more remarkable in the case of a soft synthetic resin frame. For example, a clock frame often has the same shape but different colors, but in such a case, different materials suitable for producing each color are used. These synthetic resins are often used, and the hardness naturally varies depending on the material. Since it is necessary to make the diameter of the prepared hole different depending on the material of the frame, it is necessary to make the diameter of the prepared hole different for each material even when molding a frame of the same shape. To be done. However, since it is difficult to replace the dies with materials of different hardness in terms of cost, using the same die, a boss with a larger pilot hole diameter and a boss with a smaller pilot hole diameter are adjacent to each other. Then, a boss having a prepared hole corresponding to each material is selected, and a self-tapping screw is screwed into the boss to join the frame and the parts.

However, in this case, there is a cost problem such that the structure of the frame is complicated and an unnecessary resin material for the boss is required to be additionally used.

Therefore, an object of the present invention is to provide, at a low cost, a frame connection structure that can be accommodated by a common boss even if the frame materials are different.

[0006]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the frame connecting structure of the present invention is a frame made of synthetic resin in which a boss having a prepared hole is integrally erected, and a part connected to the frame by a boss. It consists of a self-tapping screw that penetrates the through hole provided in this part and screws it into the pilot hole to join the part to the frame.The pilot hole is a large-diameter hole near the tip of the boss. It consists of a small-diameter hole that is deeper than the large-diameter hole.The self-tapping screw can be screwed on the large-diameter hole with a small amount of screwing, but it can be screwed on the small-diameter hole. It is possible to selectively select the first self-tapping screw that has a large thickness and the second self-tapping screw that can be screwed in the small diameter hole with a large amount of screwing compared to the amount of screwing, and the frame The first self-tapping screw is made of hard synthetic resin, and the frame is made of soft synthetic resin. Are those as coupling structure of a second bond strength even have different Do that synthetic resin hardness as self-tapping screw is selected sufficient frame is obtained.

[0007]

[Action]

 If the frame is made of hard synthetic resin, the first self-tapping screw can be screwed into the large-diameter hole and the part can be fixed to the tip of the boss. There is no risk of damaging the boss. If the frame is made of soft synthetic resin, use the second self-tapping screw and screw it into the small diameter hole to increase the amount of screwing without damaging the boss, and to obtain a large pulling resistance and tightening force. Be done.

[0008]

【Example】

Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1 (a), a pilot hole 3 for a self-tapping screw is provided on a boss 2 which is provided upright integrally with the frame 1. The component 4 to be joined to the frame 1 is brought into contact with the tip of the boss 2, and the self-tapping screw 5 which penetrates the through hole 4a provided in the component is screwed into the pilot hole 3 to form the frame 1. It is connected to the component 4.

FIG. 2 shows a main part of the frame. A boss 2 having a diameter D is erected integrally with the frame 1 inside the frame 1 (right in the drawing) made of a hard synthetic resin (for example, AS transparent resin). I am doing it. A counterbore hole 3a having a depth s and an inner diameter d is provided at the tip of the boss 2, and a large-diameter hole 3b having an inner diameter D1 is provided over the depth L1 following the counterbore hole. The depth L1 of the large diameter hole 3b is set to be large enough to obtain a sufficient fastening force and connection strength with a small amount of screwing.

A small-diameter hole 3c continuous with the large-diameter hole 3b is provided at a recessed position. The inner diameter D2 of the small diameter hole 3c is smaller than the inner diameter D1 of the large diameter hole 3b. The depth L2 of the small diameter hole 3c is also large enough to obtain sufficient fastening force and coupling strength, similar to L1.

FIG. 1A shows a state in which a component 4 is coupled to a frame 1 made of a hard synthetic resin by a first self-tapping screw 5 having a short length under the neck. The first self-tapping screw 5 can be screwed into the large diameter hole 3b, but cannot be screwed into the small diameter hole 3c due to its insufficient length. In the connection between the first self-tapping screw 5 and the large diameter hole 3b, since the inner diameter D1 of the pilot hole 3 is large, the screwing amount is small, which is sufficient to support the component 4. However, the boss 2 is prevented from being damaged by preventing excessive force from acting on the boss 2.

FIG. 1B shows a state in which the component 4 is coupled to the frame 11 made of soft synthetic resin (for example, PS coloring resin) by the second self-tapping screw 15. The length under the neck of the second self-tapping screw 15 is set to a length long enough to be screwed into the small diameter hole 13c of the pilot hole 13. Since the inner diameter D2 of the small-diameter hole 13c is smaller than the inner diameter D1 of the large-diameter hole 13b, it can be screwed with a larger screw-on amount than the large-diameter hole 13b. However, even if the amount of screwing is large, since it is made of soft synthetic resin, there is no possibility of damaging the boss 12.

As described above, when the frame is a hard synthetic resin frame 1, by selecting the first self-tapping screw 5 having a short neck length and screwing it in the large diameter hole 3b, While the amount of thread is set to prevent damage to the boss, when the frame is a soft synthetic resin frame 11, select the second self-tapping screw with a large neck length. Sufficient strength can be obtained by screwing the parts with the small-diameter holes 13c so as to have a large amount of screwing. When different materials are used for the frame and different diameters of the pilot holes are required, select the first self-tapping screw and the second self-tapping screw. The single selection allows the parts to be joined by the same boss.

Although the self-tapping screw has the same diameter in this embodiment, the diameter of the first self-tapping screw is set to 4 mm and the diameter of the second self-tapping screw is set to 4 mm. It is also possible to use self-tapping screws with different diameters for different materials by adopting screws with different diameters such as 3 mm and making the prepared holes corresponding to them. ..

[0015]

[Effect of the device]

 As described above, the present invention has a structure in which other parts are joined to a frame made of synthetic resin, and a large-diameter hole in which a pilot hole for a self-tapping screw is attached to one boss with a small screwing amount, and this large hole. Since there is a small diameter hole with a large amount of screwing in the deep position of the diameter hole, when the frame is hard synthetic resin, select the first self tapping screw and screw it in the large diameter hole, When the frame is made of soft synthetic resin, the second self-tapping screw can be selected and screwed with a small diameter hole, and the same pilot hole on one boss can be used. Therefore, since it is not necessary to provide a spare screwing boss, the complexity of the structure of the mold is reduced, and the amount of molding resin is reduced, so that the frames can be joined at low cost.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a state in which parts are coupled to a hard synthetic resin frame by screwing a large diameter hole with a first self-tapping screw, and a small self-tapping screw with a second self-tapping screw. It is a contrast view with a cross-sectional view showing a state in which parts are joined to a frame made of a soft synthetic resin by screwing.

FIG. 2 is a cross-sectional view showing a main part of a frame.

FIG. 3 is a cross-sectional view showing a conventional example.

[Explanation of symbols]

 1, 11 Frame 2, 12 Boss 3, 13 Prepared hole 3b, 13b Large diameter hole 3c, 13c Small diameter hole 4 Parts 4a Through hole 5,15 Self-tapping screw

Claims (1)

[Scope of utility model registration request] 1. A synthetic resin frame in which a boss having a prepared hole is integrally erected, a part connected to the frame by the boss, and a through hole provided in the part. It consists of a self-tapping screw that is screwed into the pilot hole to connect the component to the frame.The pilot hole is provided with a large diameter hole provided near the tip of the boss and a position deeper than the large diameter hole. The self-tapping screw can be screwed to the large-diameter hole with a small amount of screwing, but the self-tapping screw has a length capable of being screwed to the small-diameter hole. A screw and a second self-tapping screw that can be screwed into the small-diameter hole with a larger screwing amount than the screwing amount can be selectively selected, and the frame is made of a hard synthetic resin. When is the first
In the self-tapping screw of No. 2, when the frame is made of soft synthetic resin, the second self-tapping screw is selected.