Torsion Coil Spring Return Mechanism for Driving Tool Durability
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Solution Overview
Problem
The durability of compression coil springs in return mechanisms of driving tools is compromised by surging and collisions, leading to reduced lifespan, and existing solutions like multi-stranded twisted wire springs increase costs without further durability enhancements.
Innovation Solution
A torsion coil spring with a spring holding drum and wires that interlock with the driver's movement, utilizing elastic force for return, prevents wire collisions and reduces size and weight, eliminating the need for complex multi-stranded springs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If compression coil springs are used in the return mechanism, then the driver can be returned to the initial position using elastic force, but surging occurs and causes collisions between adjacent portions of the coiled wire, reducing durability
Solution Approach 1:
The patent divides the single coiled wire spring into multiple separate wire elements (first wire, second wire, third wire, fourth wire) that are arranged in parallel. Each wire is independently tensioned by the drum, eliminating the surge and collision problems associated with compressed coil springs while maintaining the elastic force function for returning the driver.
Solution Approach 2:
Instead of using a compressed coil spring that stores energy through compression, the patent inverts the approach by using tensioned wires that store elastic energy through stretching. The drum winds the wires to tension them, and the wires return the driver to the initial position through their elastic recovery, avoiding the harmful compression and rebound effects.
2Reliability
If multi-stranded twisted wire springs are used to suppress impairment, then durability is improved, but the structure becomes more complex and costly
Solution Approach 1:
The patent uses four separate simple wire elements instead of a complex multi-stranded twisted wire spring. Each wire is individually tensioned and arranged in parallel, achieving the desired durability through the segmented structure while keeping each individual wire simple and the overall assembly straightforward.
Solution Approach 2:
The patent combines multiple simple wire elements in parallel to achieve the durability benefits of multi-stranded construction without the complexity of twisting and interlocking strands. The wires work together through the common drum mechanism, providing enhanced durability through redundancy and distributed stress while maintaining structural simplicity.
3Reliability
If compression coil springs are used, then the return function is achieved, but the size and weight of the return mechanism increase
Solution Approach 1:
The patent replaces the bulky compressed coil spring structure with a compact arrangement of tensioned wires wound on a drum. The wires are stretched to store elastic energy, and the drum mechanism is more compact than a compression spring assembly, reducing both size and weight while maintaining the return function.
Solution Approach 2:
The patent uses thin wire elements instead of a bulky compression spring. The wires are flexible and can be wound compactly on the drum, providing the necessary elastic force with minimal mass and volume, thus reducing the overall weight of the return mechanism.
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 improves durability and reduces costs by preventing wire collisions and minimizing size and weight, while maintaining efficient operation of the return mechanism.
Implementation Method 1
a torsion coil spring (return spring) subjected to torsional moment about a central axis A1 of the coil; utilizing an elastic force of the return spring
Data Source
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AI summary
A technique is provided which contributes to improved durability of a mechanism for returning a driver to an initial position, in a driving tool that drives a fastener into a workpiece by using the driver to drive out the fastener. A nailer 1 has a driver 3, a driving-out mechanism 5 and a return mechanism 7. The driving-out mechanism 5 moves the driver 3 from an initial position to a driving position along a working axis L so as to cause the driver 3 to drive a nail 9. The return mechanism 7 returns the driver 3 from the driving position to the initial position. The return mechanism 7 has a return spring 71 which is a torsion coil spring formed by spirally winding a wire around a prescribed central axis and has a fixed end part 713 and an operation end part 715 configured to be operated in a direction crossing the central axis. The return spring 71 returns the driver 3 to the initial position by an elastic force generated when the operation end part 715 is operated in interlock with a movement of the driver 3 to the driving position.