Limiting screw suitable for precise assembly of PCB and machine shell
By designing limit screws, combined with tapered transition sections and spring structures, the problem of casing scrap caused by the superposition of machining tolerances of positioning posts was solved, achieving precise alignment between the PCB board and the casing and reliable assembly.
Patent Information
- Application Number
- CN202520208345.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-10
- Publication Date
- 2026-01-30
- Estimated Expiration
- 2035-02-10
AI Technical Summary
In the aerospace and high-precision fields, existing technologies suffer from the cumulative machining tolerances of positioning posts, which lead to overall positional errors, resulting in the scrapping of the casing. Furthermore, these technologies are difficult to adapt to diverse assembly requirements, and are time-consuming and costly.
Design a limiting screw, including a screw head, a smooth shaft section, a relief groove section, and a threaded section, combined with a tapered transition section and a spring structure, to achieve self-centering and continuous preload, eliminating the need for a positioning post.
It achieves precise alignment between the PCB board and the housing, reduces processing difficulty, avoids housing scrap, and improves assembly reliability.
Smart Images
Figure CN223854619U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to fastener technical field, concretely relates to a limiting screw suitable for the precise assembly of PCB board and casing. BACKGROUND
[0002] In the field of aerospace and other high-precision, positioning column 3 is usually used for accurate alignment of PCB board 1 on casing 2, such as Figure 1 But this traditional scheme has the following problems: the traditional assembly method usually depends on high-precision positioning column on the casing, the positioning column is formed on the casing, since the positioning column is strict in precision requirement, the overall position is easy to exceed the allowable tolerance range after the machining tolerance of multiple positioning columns is superimposed, once the machining appears out of tolerance, the casing as a whole will be scrapped, which is a serious waste. The positioning column design is usually difficult to adapt to diversified assembly requirements and must be redesigned according to different PCB hole positions and sizes.
[0003] The above technical scheme is time-consuming and cost-consuming in actual production, and has great risk, so a more efficient and reliable solution is urgently needed. CONTENT OF THE UTILITY MODEL
[0004] According to the above deficiencies in the prior art, the technical problem to be solved by the utility model is to provide a limiting screw suitable for the precise assembly of PCB board and casing, which can directly install the PCB board in a normal threaded hole, cancel the design of the positioning column, greatly reduce the machining difficulty, and improve the assembly reliability.
[0005] The limiting screw suitable for the precise assembly of PCB board and casing, comprising a screw head, a light shaft section, a tool withdrawal groove section and a threaded section arranged in sequence, the major diameter of the threaded section is greater than the diameter of the tool withdrawal groove section, the diameter of the light shaft section is greater than the major diameter of the threaded section, a tapered transition section is arranged between the screw head and the light shaft section, and a chamfer section is arranged between the light shaft section and the tool withdrawal groove section.
[0006] The tapered transition section can be in contact with the edge of the PCB hole to realize self-centering and compensate for ±0.5mm hole position deviation.
[0007] In addition, the threaded section tail is provided with a spring cavity, and a spring is arranged therein, and one end of the spring protrudes from the threaded section tail. After the screw is tightened, the spring is compressed to provide continuous pre-tightening force.
[0008] Preferably, the taper angle of the tapered transition section is 60°±2°.
[0009] Preferably, a double-thread is arranged on the threaded section.
[0010] Preferably, the taper angle of the chamfer section is 45°.
[0011] The utility model has the beneficial effect that compared with prior art:
[0012] 1. The limiting screw designed in the utility model can directly fix the PCB in the common threaded hole of the casing without processing high-precision positioning columns. The design of the screw itself ensures the precision of assembly, reduces the processing difficulty, and avoids the problem of casing scrap caused by processing out-of-tolerance.
[0013] 2. The head of the screw is designed to naturally align the threaded holes on the PCB and the casing during installation, achieving precise alignment of the center of the PCB hole and the center of the threaded hole, and ensuring assembly accuracy. BRIEF DESCRIPTION OF DRAWINGS
[0014] Figure 1 is a structural schematic diagram of the positioning and installation of the PCB and the casing through the positioning column in the prior art;
[0015] Figure 2 is a structural schematic diagram of the positioning and installation of the PCB and the casing through the limiting screw of the utility model;
[0016] Figure 3 is one of the three-dimensional structural schematic diagrams of the limiting screw;
[0017] Figure 4 is the front view structural schematic diagram of the limiting screw;
[0018] Figure 5 is the second three-dimensional structural schematic diagram of the limiting screw;
[0019] In the figure: 1, PCB; 2, casing; 3, positioning column; 4, limiting screw; 41, screw head; 42, optical axis section; 43, tool withdrawal groove section; 44, threaded section; 45, pin shaft; 46, tapered transition section; 47, chamfer section; 48, spring. DETAILED DESCRIPTION
[0020] The utility model will be further described below in combination with specific embodiments.
[0021] However, the description of the utility model is only an example of structural and functional description, and the scope of the utility model is not limited by the examples described in the text.
[0022] For example, multiple embodiments can have multiple changes and multiple forms, and it should be understood that the scope of the utility model includes equivalents that can achieve the technical idea.
[0023] For example, Figures 2 to 5As shown, the embodiment is realized by the following technical scheme: the limiting screw 4 comprises a screw head 41, an optical axis section 42, a tool withdrawal groove section 43 and a threaded section 44 arranged in sequence, the threaded section 44 is provided with double thread, the pitch is 1.5mm, and can be adapted to M3-M8 standard threaded holes. The diameter of the threaded section 44 is larger than the diameter of the tool withdrawal groove section 43, the diameter of the optical axis section 42 is larger than the diameter of the threaded section 44, a tapered transition section 46 is arranged between the screw head 41 and the optical axis section 42, the taper angle of the tapered transition section 46 is 60°±2°, which is used to contact the edge of the PCB hole to realize self-centering. A chamfer section 47 is arranged between the optical axis section 42 and the tool withdrawal groove section 43, and the taper angle of the chamfer section 47 is 45°.
[0024] The threaded section 44 tail is provided with a spring cavity, and a spring 48 is arranged in the spring cavity, the spring coefficient is 5N / mm, and the material is 65Mn steel. One end of the spring 48 protrudes from the tail of the threaded section 44, and the spring 48 provides a continuous pre-tightening force after the limiting screw 4 is tightened.
[0025] Of course, the above content is only the preferred embodiment of the present application, and cannot be considered as limiting the scope of the embodiments of the present application. The present application is also not limited to the above examples, and the equivalent changes and improvements made by the ordinary skilled in the art within the essential scope of the present application should be attributed to the patent coverage range of the present application.
Claims
1. A limit screw suitable for precise assembly of PCB board and case, characterized in that, The screw head (41), the optical axis section (42), the relief groove section (43) and the thread section (44) are sequentially arranged, the diameter of the thread section (44) is larger than the diameter of the relief groove section (43), the diameter of the optical axis section (42) is larger than the diameter of the thread section (44), a tapered transition section (46) is arranged between the screw head (41) and the optical axis section (42), and a chamfer section (47) is arranged between the optical axis section (42) and the relief groove section (43).
2. The limiting screw suitable for the precise assembly of PCB board and case according to claim 1, characterized in that, The tail of the thread section (44) is provided with a spring cavity, and a spring (48) is arranged in the spring cavity.
3. The limiting screw suitable for precise assembly of PCB board and case according to claim 1, characterized in that, The taper angle of the tapered transition section (46) is 60°±2°.
4. The limiting screw suitable for precise assembly of PCB board and case according to claim 1, characterized in that, The thread section (44) is provided with double thread.
5. The limiting screw suitable for precise assembly of PCB board and case according to claim 1, characterized in that, The taper angle of the chamfer section (47) is 45°.