Stepped Stop Pin for Power Tool Socket Retention
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Solution Overview
Problem
Existing socket holding devices for power tools, such as impact wrenches, face issues with stop pins being easily damaged and prone to coming out of mounting holes due to their soft material and long, narrow design, leading to instability and frequent damage.
Innovation Solution
A socket holding device with a stop pin featuring a stepped structure, where the first portion has a slight interference fit with the mounting hole, ensuring it cannot slide out, and the second portion has a clearance fit, made from heat-treated steel with a hardness of HRC 58-60 for durability, and the holding bolt is constructed with rotational symmetry and a narrowed part for enhanced stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a long and narrow stop pin made of soft elastic material is used, then the stop pin can be easily inserted into the mounting hole, but it breaks or suffers damage very easily and comes out of the mounting hole
Solution Approach 1:
The stop pin is divided into two distinct portions: a first portion with a larger diameter that is in interference fit with the mounting hole and clipped on the holding bolt, and a second portion with a smaller diameter that fits clearance in the mounting hole. This segmentation allows each portion to serve a specific function - the first portion provides retention and durability while the second portion facilitates easy insertion
Solution Approach 2:
Different portions of the stop pin have different diameters and material properties. The first portion has a larger diameter for interference fit and is made of heat-treated steel with high hardness (HRC 58-60) for durability, while the second portion has a smaller diameter for clearance fit and easier insertion. This local differentiation of properties resolves the contradiction between ease of insertion and durability
2Ease of operation
If the diameter of the stop pin is smaller than the mounting hole for easy insertion, then the fitting process is simpler, but the stop pin can slide out of the mounting hole
Solution Approach 1:
The stop pin is segmented into two portions with different diameters. The first portion has a diameter larger than the mounting hole for interference fit and retention, while the second portion has a diameter smaller than or equal to the mounting hole for easy insertion. This segmentation allows the pin to be inserted easily while preventing it from sliding out
Solution Approach 2:
The diameter parameter of the stop pin is changed along its length, creating a stepped structure. The first portion has a larger diameter for interference fit that prevents sliding out, while the second portion has a smaller diameter for easy insertion. This parameter change along the length of the pin resolves the contradiction between retention stability and fitting convenience
3Ease of manufacture
If a soft material with elasticity is used for the stop pin, then the stop pin can be forcibly pressed into the mounting hole, but it breaks or suffers damage very easily
Solution Approach 1:
The material parameter of the stop pin is changed from soft elastic material to heat-treated steel with high hardness (HRC 58-60). This parameter change increases the strength and resistance to damage of the stop pin while maintaining the ability to be fitted into the mounting hole through the interference fit mechanism of the first portion
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 provides a structurally simple, stable, and durable socket holding device that prevents the stop pin from coming out and reduces the risk of damage, ensuring reliable operation and improved fitting convenience.
Implementation Method 1
the diameter of the first portion of the stop pin that is clipped on the holding bolt is larger than the diameter of the mounting hole which accommodates the stop pin, i.e. the first portion of the stop pin is in a slight interference fit with the mounting hole
Implementation Method 2
the stop pin is made from heat-treated steel with a hardness of HRC 58-60 for durability
Data Source
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AI summary
The present invention provides a socket holding device for a power tool, comprising an anvil, on which anvil are provided a drive square head for clipping a tool, and a holding bolt for locking a clipped tool element, the holding bolt being supported elastically in the drive square head in such a way as to be moveable perpendicular to a rotation axis of the anvil, the holding bolt being locked by at least one stop pin disposed in a mounting hole of the drive square head, the stop pin comprising a first portion partially clipped on the holding bolt; the diameter of the first portion of the stop pin is slightly larger than the inner diameter of the mounting hole. The socket holding device for a power tool of the present invention is structurally simple, stable and durable.