Connecting Device Thread Contour for Chip Prevention
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Solution Overview
Problem
Screw connections in machine elements, particularly in cartridge valves, suffer from component contamination due to metallic chips and particles formed during screwing processes, which can disrupt the functionality and increase wear by entering the fluid circuit.
Innovation Solution
A connecting device with a modified thread geometry, specifically altering the first thread turn to reduce contamination, such as a chamfered cut with an angle less than 40°, a rounded cut, or a spiral that widens at an angle, to minimize contact surface and prevent dirt entry into the installation space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a standard thread geometry with 45° chamfered cut is used on the first thread turn, then the screwing process is simple and fast, but metallic chips and particles are generated that contaminate the installation space and fluid circuit
Solution Approach 1:
The patent applies different geometric properties to different parts of the thread. Specifically, the first thread turn has a modified contour (chamfered cut with angle <40°, rounded cut, or spiral groove) compared to the standard 45° chamfer, while subsequent thread turns maintain the standard geometry. This local differentiation reduces chip generation at the critical first engagement point without compromising the overall screwing efficiency
Solution Approach 2:
The thread is divided into two functional segments: the first thread turn with modified contour designed to minimize contamination, and subsequent thread turns with standard geometry designed for efficient fastening. This segmentation allows each part to optimize its specific function - the first turn protects the installation space while the remaining turns provide secure connection
2Object-affected harmful factors
If the contact surface of the first thread turn is reduced through contour modification, then contamination is minimized, but the screwing-in process may become more complex
Solution Approach 1:
The patent modifies specific geometric parameters of the first thread turn - primarily the chamfer angle (reducing it from the standard 45° to less than 40°, preferably 20°-30°), or introduces rounding radius, or adds spiral groove parameters. These controlled parameter changes achieve the contamination reduction goal while maintaining compatibility with standard threading processes and tools
Data Source
Figure 1~2d
Figure 3~4d
Figure 5~6d
AI summary
2. A connecting device, comprising at least an external thread (12) on a screw-in part (2) which is screwed into an internal thread (20) of a receiving part (4), wherein during the screwing-in process metallic chips and/or particles are formed between the threads (12, 20) as component contamination, is characterized in that, viewed in the screwing-in direction, at least the first thread (22) of the screw-in part (2) is provided with a contour change compared to the other threads of this thread (12) in such a way that component contamination is prevented or substantially prevented.