Metal Sheet Handle Protector with Snap-Fit Protrusions

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Solution Overview

Problem

Existing handle protectors for hand tools are either costly to manufacture, require complex processes, or fail to securely attach to the handle, leading to damage from accidental impacts and vibration propagation.

Innovation Solution

A handle protector made from a metal sheet with a U-shape and protrusions that snap-fit into the handle, using injection molding for secure attachment and incorporating indentations for impact energy absorption, which is cost-effective and simple to manufacture.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the handle protector is made from a metal sheet with simple manufacturing processes, then the manufacturing cost is reduced and manufacturing complexity is simplified, but the attachment reliability may be compromised

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidattachment reliability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The handle protector is nested within the handle structure, with side members extending into grooves on the handle surface. The protrusions on the handle are embedded within recesses of the protector, creating a nested configuration that achieves secure attachment through geometric interlocking rather than mechanical fasteners.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

An adhesive substance acts as an intermediary between the handle protector and the handle, filling the gap between the two components and creating a reliable bond. This intermediary material enables secure attachment while allowing the use of simple metal sheet manufacturing processes.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If mechanical attachments such as rivets or interference fits are used to secure the handle protector, then the attachment reliability is improved, but the manufacturing complexity and cost increase

Engineering Contradiction:
Improveattachment reliabilityVSAvoidattachment complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The complex mechanical attachment mechanisms (rivets, interference fits, welding) are extracted from the design and replaced with a simpler geometric interlocking system using protrusions and grooves, combined with adhesive bonding. This removes unnecessary complexity while maintaining attachment reliability.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

Traditional mechanical attachment systems are replaced with a combination of geometric interlocking (protrusions fitting into grooves) and chemical bonding (adhesive). This substitution eliminates the need for rivets, welds, or interference fits, simplifying the overall attachment mechanism.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Strength

If the handle protector is made from costly materials with high strength, then the impact protection capability is improved, but the manufacturing cost increases

Engineering Contradiction:
Improveimpact resistanceVSAvoidmanufacturing cost
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The handle protector applies local quality by concentrating protective features only where needed: protrusions are positioned at impact-prone areas to absorb and distribute impact forces, while the overall structure uses a cost-effective metal sheet material rather than expensive high-strength alloys throughout.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The handle protector uses a cost-effective metal sheet material that provides sufficient protection for its intended service life. Rather than using expensive, ultra-durable materials, the design accepts that the protector may need replacement over time, optimizing for initial cost and manufacturability while maintaining adequate protective performance.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

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 handle protector effectively absorbs impact energy, reduces vibration transmission, and securely attaches to the handle without the need for costly manufacturing processes or mechanical attachments, enhancing the durability and usability of hand tools.

Implementation Method 1

An interface formed between the portion for retaining heated thermoplastic material in the adapted implement head and the thermoplastic material retained thereby forms a bond joining the adapted implement head and the injection molded handle.

Methodology Applied
Scientific EffectInjection molding:

Implementation Method 2

the handle protector includes a front member and two side members. Further, the front member and the side members form a substantially U-shape... Each side member includes at least one protrusion. Further, each protrusion extends into a corresponding groove on the handle.

Methodology Applied
Scientific EffectImpact energy absorption: Impact Force

Data Source

PatentEP3332919B1Handle protector for a hand tool
Publication Date: 2020.12.23 HUSQVARNA AB
  • EP3332919B1 patent drawingFigure 1
  • EP3332919B1 patent drawingFigure 2A~2D
  • EP3332919B1 patent drawingFigure 3A~3C

AI summary

A hand tool (100, 200, 300) includes a working head (102), a handle (104) connected to the working head (102), and a handle protector (110, 302, 502) attached to the handle (104) proximate the working head (102). The handle protector (110, 302, 502) is manufactured from a metal sheet. Further, at least one portion of the handle protector (110, 302, 502) extends into the handle (104) to facilitate attachment of the handle protector (110, 302, 502) to the handle (104).