Coil Spring Antivibration Mounting With Captive Screw Access
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Solution Overview
Problem
Existing hand-held tools with anti-vibration elements face complex assembly processes due to the risk of fastening screws being lost or unintentionally loosened, requiring multiple screwing operations and additional components for secure mounting.
Innovation Solution
A hand-held tool design featuring a fastening screw with an engagement contour accessible through an opening in the second assembly, allowing pre-positioning within the coil spring, simplifying assembly by reducing the number of required screwing operations and preventing screw loss or loosening, with an anti-twist device securing the fastening eyelet against twisting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the fastening screw is accessible through an opening in the second assembly, then the assembly process is simplified and the screw cannot fall out, but the opening requires precise dimensional control to prevent screw loss
Solution Approach 1:
The fastening screw head is nested within the coil spring interior during assembly, with the opening in the second assembly providing access to the engagement contour. The opening dimension is controlled to be larger than the screw head diameter to prevent the screw from falling out while still allowing tool access for tightening.
Solution Approach 2:
The fastening screw is pre-positioned inside the coil spring before the coil spring is mounted to the second assembly. This preliminary positioning ensures the screw cannot fall out during subsequent assembly operations, and the opening is designed to accommodate this pre-positioned state.
2Reliability
If multiple screwing operations are required to secure the anti-vibration element, then reliable fastening is achieved, but the assembly process becomes complex and time-consuming
Solution Approach 1:
The fastening screw is preliminarily positioned inside the coil spring before mounting to the second assembly. This preliminary action eliminates the need for separate operations to insert and secure the screw, reducing the total number of screwing operations while maintaining reliable fastening through the engagement contour design.
Solution Approach 2:
The mounting of the coil spring to the second assembly and the securing of the fastening screw are combined into a single operational sequence. The opening in the second assembly allows both the coil spring mounting and screw tightening to be accomplished through the same access point, merging multiple operations into one efficient process.
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 significantly simplifies the assembly of anti-vibration elements by reducing the number of screwing operations to two, ensuring secure fastening without additional components, and allowing flexible positioning of the second assembly during assembly, thereby enhancing assembly efficiency and reducing the risk of screw loss or partial unscrewing.
Implementation Method 1
The anti-vibration elements have coil springs, each of which is fixed to the motor unit with a screw
Data Source
Figure 1~2
Figure 3~5
Figure 6~9
AI summary
A hand-held tool comprises a first assembly (31), a second assembly (32), and at least one anti-vibration element (10). The anti-vibration element (10) comprises a coil spring (15). A first end (19) of the coil spring (15) forms a mounting eyelet (21) at which the coil spring (15) has a reduced outer diameter (e). The first end (19) of the coil spring (15) is fixed to the first assembly (31) by a mounting screw (16). The mounting screw (16) extends through the mounting eyelet (21), and the head (24) of the mounting screw (16) projects into the interior (33) of the coil spring (15). A second end (20) of the coil spring (15) is screwed onto a fitting (18) of the second assembly (32). The head (24) of the mounting screw (16) has an engagement contour (17).The second assembly (32) has an opening (22) extending through the nozzle (18) and through which the engagement contour (17) in the head of the fastening screw (16) is accessible to a tool. The inner diameter (a) of the opening (22) is smaller than the outer diameter (b) of the head (24) of the fastening screw (16). A method for mounting the anti-vibration element (10) involves, in a first step, positioning the head (24) of the fastening screw (16) in the coil spring (15), in a second step, screwing the coil spring (15) to the nozzle at its second end (20), and in a third step, screwing the fastening screw (16) into the first assembly (31).