Hollow Tool Handle Segmentation and Foam Nesting
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Solution Overview
Problem
Existing methods for manufacturing tool handles, such as those for axes, shovels, and hammers, face challenges in achieving a hollow design while maintaining shape flexibility and ensuring safety and stability, particularly with plastic handles where gassing processes result in varying wall thicknesses and traditional injection molding methods restrict curved shapes.
Innovation Solution
The handle is formed by connecting at least two handle parts, which can be designed as half-shells with a separating plane that can be curved, allowing for a hollow cavity that can be filled with foam for added stability, and using a fastening area with bolts for secure attachment of the tool part, enabling ergonomic and aesthetically pleasing designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the handle is made hollow by gassing process, then weight is reduced, but wall thickness varies which compromises safety
Solution Approach 1:
The handle is divided into multiple segments (first handle part, second handle part, third handle part) that are connected together. This segmentation allows each part to maintain uniform wall thickness while the overall structure remains hollow and lightweight, resolving the contradiction between weight reduction and safety.
Solution Approach 2:
The hollow cavity within the handle segments is nested with a foam core material. This nested structure provides internal support that maintains uniform wall thickness and structural integrity, eliminating the wall thickness variation problem while preserving the weight benefits of the hollow design.
2Ease of manufacture
If a core is pulled out of the handle during injection molding, then manufacturing is simplified, but the handle must be shaped straight which limits design freedom
Solution Approach 1:
The handle is manufactured as multiple separate segments that can be molded with complex curved shapes without requiring straight-core extraction. Each segment is independently molded and then assembled, enabling ergonomic curved designs while maintaining manufacturing simplicity through modular production.
Solution Approach 2:
The handle segments are pre-formed with their final curved shapes during injection molding before assembly. The fastening areas and connection features are also preliminarily formed during molding, eliminating the need for post-molding shaping operations and enabling complex ergonomic designs.
3Shape
If multiple handle parts are connected together, then shape flexibility and ergonomics are improved, but device complexity increases
Solution Approach 1:
Multiple handle parts are merged into a single integrated structure through the fastening area mechanism. The first, second, and third handle parts are connected via fastening elements that integrate them functionally as one piece, providing ergonomic curved shapes without the complexity of separate adjustable components.
Solution Approach 2:
The handle segments are designed with multi-functional features: they provide structural support, enable ergonomic shaping, incorporate fastening mechanisms for the tool part, and create hollow cavities for weight reduction. This multi-functionality reduces the need for additional specialized components, simplifying the overall device.
4Weight of moving object
If the handle is hollow for weight reduction, then weight decreases, but structural stability is compromised
Solution Approach 1:
A foam core material is nested within the hollow cavity of the handle segments. This nested foam provides internal structural support that maintains handle stability and rigidity while the outer hollow structure preserves weight reduction benefits.
Solution Approach 2:
The handle employs a composite structure combining the outer hollow plastic shell with an inner foam core material. This composite design integrates the weight-saving properties of the hollow plastic structure with the stabilizing properties of the foam core, achieving both light weight and structural stability.
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
This approach allows for the creation of tools with more ergonomic and stable handles that can be manufactured efficiently, providing improved safety and aesthetic appeal while maintaining structural integrity and flexibility in shape, overcoming the limitations of prior methods.
Implementation Method 1
This cavity can be empty (i.e. filled with air or gas) or it can be filled with foam, which can counteract the introduction of moisture.
Implementation Method 2
In the manufacturing process, the two half-shells are first joined and then a shell is overmolded in an injection molding machine at high pressure.
Data Source
Figure 1
Figure 2a~2e
Figure 2f~2h
AI summary
Tool with a handle (2) and a tool part (3) attached to the handle (2), in particular an axe head, wherein the handle (2) is formed by at least two handle parts (4) which are connected to each other and of which at least one is connected to the tool part (3), wherein the at least two handle parts (4) are surrounded by a sheath (5).