Impact Driver Bit Holder Structure for Smooth Insertion and Durability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing tool-holding apparatuses in electric work machines, such as impact drivers, face issues with durability due to stress concentration at narrowed portions and difficulty in inserting bits when the bit sleeve is axially positioned incorrectly, leading to potential blockage of engaging members and reduced insertion efficiency.
Innovation Solution
A tool-holding apparatus with movable engaging members and biasing members that allow axial and radial movement, featuring a bit sleeve that can switch between blocking and permitting positions, and a positioning part to stabilize the bit sleeve, ensuring smooth bit insertion regardless of its axial position relative to the rotational-output shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the tool holder narrows at the front end to restrict radial movement, then radial stability is improved, but cracks form in the narrowed portion under impact loads
Solution Approach 1:
The tool holder is divided into a front end portion and a rear end portion with different structural characteristics. The front end has a larger outer diameter for strength, while the rear end narrows for radial stability during bit insertion.
Solution Approach 2:
Different portions of the tool holder have different outer diameters optimized for different functions: the front end has a larger diameter to resist impact loads and prevent cracks, while the rear end has a smaller diameter to provide radial stability during bit insertion.
2Reliability
If the engaging members are biased forward to engage the bit, then bit retention is improved, but the bit cannot be inserted when the bit sleeve is forward
Solution Approach 1:
The bit sleeve's axial position is dynamically adjusted: positioned forward during operation to maintain bit retention through radial engagement, and moved rearward during bit insertion to allow the bit to pass by the engaging members.
Solution Approach 2:
The biasing member preliminarily positions the bit sleeve forward to ensure the engaging members are ready to engage the bit immediately upon insertion, improving retention reliability.
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
Enhances the durability of the rotational-output shaft by reducing stress concentration and allows for effortless bit insertion and secure mounting, improving the overall operational efficiency and user experience.
Implementation Method 1
a first biasing member, which biases the engaging member(s) in a direction (e.g., an axially forward direction) that causes the engaging member(s) to engage with (in) the tool accessory
Implementation Method 2
a second biasing member, which biases the bit sleeve toward the blocking position
Data Source
AI summary
A tool-holding apparatus (70) includes an engaging member (71) for engaging a tool accessory (B) and being movably supported in axial and radial directions in a rotational-output shaft (26) having an insertion hole (81) for holding the tool accessory (B). A first biasing member (72) biases the engaging member towards engagement with the engaging member. A bit sleeve (73) is movable in the axial direction along an outer-circumferential surface of the rotational-output shaft between a blocking position at which radial outward movement of the engaging member is blocked and a permitting position at which radial outward movement of the engaging member is permitted. A second biasing member (74) biases the bit sleeve toward the blocking position. A positioning part (75) is fixed on the outer-circumferential surface of the rotational-output shaft and stops the bit sleeve at the blocking position. The bit sleeve has a projection (88), which is disposed on the forward side of the first biasing member, extends inward in the radial direction, and slidably contacts the rotational-output shaft.