Trowel Blade Cleat Attachment System
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Solution Overview
Problem
The challenge in attaching a handle to a hardened and tempered trowel blade without compromising its structural integrity or surface finish, as traditional methods like welding can cause warping, brittleness, or surface damage, and existing rivet-based systems often result in surface irregularities and gaps between the blade and handle.
Innovation Solution
A system involving pre-finished, hardened and tempered trowel blades with tapering apertures and integral, rigid cleats that are deformed within these apertures to form a frusto-conical shape, providing a secure and rigid interface with a removable handle without heat-induced damage, using a method that clinches the cleats within the apertures to resist rotation and ensure a constant seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If welding is used to attach a handle to the blade, then a strong bond is achieved, but the blade warps, becomes brittle, loses hardness, and surface finish is marred
Solution Approach 1:
The attachment system is divided into separate components: the blade, the engagement cleat, and the handle. The cleat is inserted through the hardened blade and secured by deformation, avoiding direct thermal contact with the blade while achieving strong mechanical bonding.
Solution Approach 2:
The engagement cleat acts as an intermediary component between the blade and handle. It transfers the bonding function away from the blade itself, allowing the handle to be attached without applying heat directly to the blade, thus preserving the blade's heat-treated properties.
2Strength
If welding is used to attach a handle to the blade, then a strong bond is achieved, but the surface finish is damaged and corrosion resistance is reduced
Solution Approach 1:
The attachment function is segmented from the blade surface, using a separate cleat component that passes through the blade. This prevents direct contact between the bonding process and the blade's surface finish, preserving the brushed appearance and corrosion resistance.
Solution Approach 2:
The engagement cleat serves as an intermediary that carries the bonding function away from the blade surface. The handle attaches to the cleat rather than directly to the blade, preventing surface damage while maintaining bond strength.
3Reliability
If rivets are used to attach a handle to the blade, then heat-induced damage is avoided, but surface irregularities occur and gaps form between the blade and handle
Solution Approach 1:
The apertures are pre-formed in the blade with a tapered geometry that guides the engagement cleat during insertion. The larger opening at the bottom accommodates the cleat as it is inserted, and the tapering toward the top ensures proper positioning before the cleat is deformed to secure it.
Solution Approach 2:
The aperture cross-section changes parameterically from a larger opening at the bottom to a smaller opening at the top. This gradual parameter change allows the engagement cleat to be inserted smoothly without causing surface irregularities, while still providing sufficient material for secure deformation and attachment.
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 solution provides a secure, heat-free attachment method that maintains the blade's structural integrity and surface finish, preventing material seepage between the handle and blade, while ensuring a consistent interface and preventing surface irregularities.
Implementation Method 1
each cleat can have a lower portion, deformed within the aperture to have a frusto-conical shape mating with internal walls of the aperture
Data Source
AI summary
A trowel blade includes a pre-finished, hardened and tempered blade having at least two apertures formed therethrough. Each aperture has a cross section tapering from a larger opening in a bottom of the blade to a smaller opening in a top of the blade. At least two cleats are also provided, each cleat being disposed in one of the apertures and each cleat having a lower portion, deformed within the aperture to have a frusto-conical shape mating with internal walls of the aperture. Each cleat also has an upper, inverted frusto-conical portion having a lower surface mating with an upper surface of the blade, and an upper shoulder. The upper shoulder of the upper portion extends upwardly from the lower surface of the upper portion and outwardly from a longitudinal axis of the cleat. The cleats are formed of an integral, rigid material and are collectively configured to provide a substantially rigid interface between the pre-finished blade and a removable handle of the pre-finished blade.