Anti-falling screw

Abstract

The utility model relates to a fastener, in particular to an anti-falling screw for a high-end clock movement. The utility model relates to a screw and aims to provide an anti-loosening screw to solve the problem of high failure rate caused by loosening of the screw. According to the technical scheme, the anti-falling screw comprises a screw head and a screw rod; the screw rod is provided with a sawtooth-shaped external thread, and the thread angle of the external thread is larger than that of the internal thread of the nut.

Description

TECHNICAL FIELD

[0001] The utility model relates to a fastener, in particular to a screw for preventing the high -end clock movement. BACKGROUND

[0002] The clock screw used in the market at present is all ordinary 60-degree tooth type screw. Because there is certain free gap between the screw outer diameter and the nut outer diameter, all these gaps will cause certain freedom (as shown in the figure) around the screw, and the screw is prone to loosening under the vibration, thereby obviously increasing the failure rate and causing the waste of resources and manpower. Figure 6 OBJECT OF THE INVENTION TECHNICAL SOLUTION

[0003] The utility model discloses a screw for preventing, to solve the problem of high failure rate caused by screw loosening.

[0004] The utility model discloses a technical scheme:

[0005] The screw for preventing comprises a screw head and a screw rod. The screw rod is provided with sawtooth-shaped external thread, and the tooth type angle of the external thread is greater than the tooth type angle of the internal thread of the nut.

[0006] The tooth type angle of the external thread is 90 degrees.

[0007] The included angle between the upper tooth side of the external thread and the plane perpendicular to the screw axis is 60 degrees, and the included angle between the lower tooth side of the external thread and the plane perpendicular to the screw axis is 30 degrees.

[0008] The length of the screw rod is 0.8-1.2mm, and the outer diameter is 0.3-1.0mm.

[0009] The outer diameter of the screw head is 1.0-2.0mm.

[0010] The utility model has the advantages of simple structure, low cost, and that the screw is not prone to loosening under the vibration after assembly, greatly reducing the failure rate caused by screw loosening, saving the waste of manpower and time, and being suitable for wide range of use in high-end clock movement.

[0011] The utility model discloses a technical scheme: DRAWINGS

[0012] Figure 1 It is the main view structural schematic diagram of the utility model.

[0013] Figure 2 It is Figure 1 The enlarged structural schematic diagram of A part in the figure.

[0014] Figure 3is an assembly drawing of the utility model.

[0015] Figure 4 is a schematic diagram of engagement state of thread and nut of the utility model.

[0016] Figure 5 is a schematic diagram of engagement state of thread and nut of the utility model.

[0017] Figure 6 is a schematic diagram of prior art.

[0018] Reference signs: screw head 1, screw rod 2, nut 3. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical scheme and advantages of the utility model more clearly, the following will be further detailed in combination with the drawings and examples.The specific examples described here are only used to explain the utility model and not to limit the utility model.

[0020] As Figure 1 shown, the anti-loose screw includes screw head 1 and screw rod 2.

[0021] The length of the screw rod is 0.8-1.2mm, and the outer diameter is 0.3-1.0mm.The outer diameter of the screw head is 1.0-2.0mm.

[0022] The screw rod is provided with sawtooth-shaped external thread (the cross section of the external thread is sawtooth-shaped), and the tooth profile of the external thread is divided into upper tooth side 2-1 and lower tooth side 2-2 on both sides, and the tooth profile angle α between the upper tooth side and the lower tooth side is greater than the internal thread tooth profile angle of the nut 3, that is, α>60°.

[0023] As preferred, the tooth profile angle α between the upper tooth side and the lower tooth side is 90 degrees, the included angle between the upper tooth side and the plane perpendicular to the screw axis is 60 degrees, and the included angle between the lower tooth side and the plane perpendicular to the screw axis is 30 degrees.In addition, the lower tooth side of the external thread is also parallel to the upper tooth side of the internal thread of the nut.

[0024] As Figure 4 shown, when the outer diameter of the anti-loose screw is the smallest, the internal thread tooth top of the nut contacts the tooth bottom of the external thread of the anti-loose screw.

[0025] As Figure 5 shown, when the outer diameter of the anti-loose screw is the largest, the internal thread tooth top of the nut contacts the upper tooth side of the external thread of the anti-loose screw.

[0026] The advantage is that the outer thread minor diameter of the screw rod is larger than that of the prior art, the outer thread major diameter of the screw rod is smaller than that of the prior art, and the screw and the nut are in linear contact. Regardless of whether the outer diameter of the anti-loosening screw is the minimum value or the maximum value due to the tolerance, the screw and the nut can always be engaged, that is, the tooth top of the inner thread of the nut and the upper tooth side of the outer thread of the anti-loosening screw are always in linear contact, the contact area is unchanged, the manufacturing tolerance does not affect the assembly quality, so that the screw is prevented from loosening under the action of vibration, and the failure rate is reduced.

[0027] In the prior art, as shown in Figure 6 When a 60-degree tooth profile angle is used, the screw and the nut are in surface contact. In terms of tolerance, when the tolerance is the minimum, the theoretical contact surface between the screw and the nut is the maximum, and the loosening phenomenon is weakened. When the tolerance is the maximum, the theoretical contact surface between the screw and the nut is the minimum, and the loosening phenomenon is more obvious, thereby increasing the failure rate. For example, on the S1.0x0.25 assembly, there is a free space of 0.05mm radius between the outer diameter of the screw and the outer diameter of the nut. All these spaces leave a certain degree of freedom for the screw, and under the action of vibration, the screw can be loosened. Therefore, a thread locking agent (glue) needs to be used to prevent vibration, but this method is not suitable for assembly (watchmaking industry, etc.) where visual effect is very important. The utility model does not need to use a thread locking agent.

[0028] The preferred embodiments of the utility model are shown in the drawings. However, the utility model can be realized in many different forms and is not limited to the embodiments described in the specification. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the utility model more thorough and comprehensive.

Claims

1. A lock-on screw, comprising a screw head (1) and a screw shank (2); characterized in that: The screw rod has a sawtooth-shaped external thread, and the thread angle of the external thread is greater than the thread angle of the internal thread of the nut.

2. The anti-loosening screw according to claim 1, characterized in that: The thread angle of the external thread is 90 degrees.

3. The anti-loosening screw according to claim 2, characterized in that: The angle between the upper tooth side of the external thread and the plane perpendicular to the screw axis is 60 degrees; the angle between the lower tooth side of the external thread and the plane perpendicular to the screw axis is 30 degrees.

4. The anti-loosening screw according to claim 3, characterized in that: The length of the screw rod is 0.8-1.2 mm, and the outer diameter is 0.3-1.0 mm.

5. The anti-loosening screw according to claim 4, characterized in that: The outer diameter of the screw head is 1.0-2.0 mm.

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