Hand Tool Return Spring Pocket Design

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Solution Overview

Problem

Existing hand tools, such as pliers, face challenges in manufacturing and user convenience due to the difficulty in installing or removing return springs without disassembling the tool halves, and the need for pre-assembly of springs during manufacturing.

Innovation Solution

A design featuring a pocket-like recess in one tool half for the return spring, allowing it to be inserted after assembly, with spring ends that engage via frictional or positive connections, enabling easy retrofitting and adjustment of the spring characteristics post-production.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the return spring is installed before or during assembly of tool halves, then the spring is securely positioned, but subsequent installation or removal is impossible or difficult without dismantling the tool halves

Engineering Contradiction:
Improvespring positioningVSAvoidspring installation/removal
Core Design Contradiction:
ReliabilityVSEase of repair

Solution Approach 1:

The tool is divided into separable components: the tool halves form a complete assembly, while the return spring is a separate modular element that can be independently installed or removed. The pocket-like recess provides a dedicated space that accommodates the spring without requiring permanent integration into the tool half structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The return spring is extracted from the traditional integrated positioning method and placed into a dedicated pocket-like recess. This extraction allows the spring to be removed from the tool assembly without dismantling the tool halves, while still maintaining secure positioning during operation.

Inventive Principle:
Principle #2Taking out (Extraction)

2Ease of operation

If the manufacturer pre-assembles the return spring with tool halves, then the tool is ready for use, but double storage and differentiation are necessary during manufacturing

Engineering Contradiction:
Improvetool readinessVSAvoidmanufacturing process
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The pocket-like recess is pre-formed in the tool half during manufacturing, creating a ready-to-receive structure. However, the actual spring installation is deferred to a later stage, allowing the tool halves to be manufactured and stored without the complexity of pre-assembling different spring configurations.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The pocket-like recess serves multiple functions: it guides spring installation, secures the spring during operation, and allows for easy removal. This universal structure eliminates the need for different manufacturing processes for tools with or without return springs.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Ease of operation

If the return spring extends outside the overlapping area, then the spring is accessible, but it may interfere with the tool's operation or get caught in projections

Engineering Contradiction:
Improvespring accessibilityVSAvoidspring interference
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The return spring is nested within the pocket-like recess formed in the tool half. This nesting configuration allows the spring to be accessible for installation and operation while being contained within the tool's structure, preventing interference with external objects or projections.

Inventive Principle:
Principle #7Nested doll (Nesting)

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 design simplifies the assembly and disassembly of return springs, allows for late-stage equipping of tools with springs, and prevents spring interference with the tool's operation, enhancing both manufacturing efficiency and user convenience.

Implementation Method 1

the spring ends are shaped in such a way that they are held on corresponding counter-formations of the tool halves via frictional connection

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

a return spring which acts in a plane spanned by the handle-side leg of the tool halves and supports the opening movement

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3313618B1Hand tool
Publication Date: 2021.05.19 ORBIS WILL
  • EP3313618B1 patent drawingFigure 1
  • EP3313618B1 patent drawingFigure 2
  • EP3313618B1 patent drawingFigure 3

AI summary

The invention relates to a hand tool (1) with two tool halves (2, 3) which are arranged so as to cross each other in a joint region and which are connected together in a pivotal manner, in particular in the form of pliers, shears, or the like. One tool half (2, 3) forms a jaw (7, 8) on one side of the joint and a grip on the other side of the joint. A leg or torsion spring which acts on a plane spanned by the grip-side limb (5, 6) of the tool halves (2, 3) and which supports the opening movement is arranged between the limbs (5, 6) of the tool halves (2, 3) on the grip-side of the tool halves (2, 3), and the tool halves (2, 3) can extend relative to each other so as to overlap in the region of the joint in an overlap region (U).The aim of the the invention is to further improve a hand tool (1), in particular pliers, shears, or the like, which has an advantageous design in terms of production. This is achieved in that the rotational axis of the joint lies outside of the contours of the restoring spring (11), and the spring ends (19) are formed such that the spring ends can be fixed or rest on the corresponding counter recesses (16) in the operative position by means of a force-fitting connection or a supporting form-fitting connection and/or the restoring spring (11) extends partly in the overlap region (U) between an upper tool half (2, 3) and a lower tool half (2, 3).