Threaded Connecting Link Structure to Prevent Chain Stretching
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Solution Overview
Problem
Existing chains face issues with undesirable stretching due to friction between the coupling pin and the pin hole, which occurs when the coupling pin is in a clearance fitting state, and the burden of fitting and removing the pin in an interference fitting state.
Innovation Solution
A connecting link with a coupling pin featuring a male threaded portion, a first truncated conical portion, and a second truncated conical portion, along with link plates having corresponding female threaded and conical pin holes, allows for interference fitting without the need for hydraulic equipment, ensuring the pin is securely fastened and prevents sliding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the coupling pin is in a clearance fitting state, then the user can readily remove or fit the pin, but friction from aging enlarges the pin hole diameter causing chain stretching
Solution Approach 1:
The pin hole diameter is changed along the axial direction to create different fitting states at different locations. The large-diameter portion allows easy insertion and removal, while the small-diameter portion provides interference fitting to prevent sliding and chain stretching. This parameter variation resolves the contradiction between ease of operation and reliability.
2Reliability
If the coupling pin is in an interference fitting state, then chain stretching is prevented, but the pin requires hydraulic equipment or large hammer for fitting and removal
Solution Approach 1:
Different portions of the pin hole have different diameters to provide different functions. The large-diameter portion at the insertion end facilitates easy pin insertion and removal, while the small-diameter portion at the retention end provides interference fitting to prevent chain stretching. This local quality differentiation resolves the contradiction between reliability and ease of operation.
3Adaptability or versatility
If the coupling pin is freely rotatable in the pin hole, then the chain allows rotation, but the pin surface slides along the hole wall causing friction and aging
Solution Approach 1:
The pin hole diameter is varied along the axial direction, with a large-diameter portion allowing free rotation and a small-diameter portion creating interference fitting to prevent sliding. This parameter change enables the chain to rotate while preventing friction and wear from pin sliding along the hole wall.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution prevents undesirable stretching of the chain by maintaining a secure fit of the coupling pin, reducing the effort required for breaking and connecting the chain, and limiting separation during use.
Implementation Method 1
the outer surface of the connecting pin will slide along the wall surface of the pin hole. Thus, friction resulting from aging may enlarge the diameter of the pin hole
Implementation Method 2
a first pin hole including a female threaded portion allowing for fastening of the male threaded portion
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A joint link (14) includes joint pins (33), a first link plate (31), and a second link plate (32). The joint pins (33) each have a first male threaded portion (36) at the base end. The joint pins (33) also each have, on the distal side of the first male threaded portion (36), a first frustum-shaped portion (38), the cross-sectional area of which gradually increases toward the base-end side. The first link plate (31) has holes at both longitudinal ends through which the joint pins can be inserted. At least one of the holes at both ends constitutes a first pin hole (44) having a female threaded portion into which a first male threaded portion can be screwed, and an inner surface (44a) with a concave conical surface shape corresponding to the outer surface (38a) of the first frustum-shaped portion. The second link plate (32) has holes at both longitudinal ends through which the joint pins can be inserted. At least one of the holes at both ends constitutes a second pin hole (48) into which the tip end of a joint pin can fit.