Non-rusting Polymer Trowel Blade with Flush Bottom

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Solution Overview

Problem

Conventional power trowel blades often leave trowel marks, chatter marks, and can damage the surface finish due to protrusions, voids, and metal components that rust or cause dark burn marks, and require additional metal bars for support which can lead to concrete accumulation and hardening issues.

Innovation Solution

A flush-bottom, single-piece trowel blade made from non-rusting polymer material with threaded inserts and recesses for mounting, eliminating the need for additional bars and reducing the risk of trowel marks through its curved design and flexible construction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a metal bar or channel is used for mounting the blade, then the blade can be securely connected to the trowel arm, but the metal components can rust and leave dark burn marks on the surface

Engineering Contradiction:

Improvemounting securityVSAvoidrust and dark burn marks

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention extracts and removes the metal bar or channel mounting component from the blade assembly. The blade is now mounted directly to the trowel arm through threaded inserts embedded in the blade itself, eliminating the intermediate metal mounting bar that caused rust and dark burn marks on the finished surface

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces durable metal mounting components with a blade design that integrates mounting threads directly into the blade body. The blade itself becomes the mounting component, using non-metallic material that doesn't rust, effectively making the mounting system disposable with the blade rather than a separate long-lived metal component

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Stability of the object's composition

If the blade is made completely flat and rigid, then it provides structural stability, but it causes trowel marks and chatter marks on the finished surface

Engineering Contradiction:

Improvestructural stabilityVSAvoidtrowel marks and chatter marks

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The invention applies curvature to the bottom surface of the blade, specifically creating a concave or curved profile instead of a completely flat rigid surface. This curvature allows the blade to conform to the finished surface without creating trowel marks or chatter marks, while the overall blade structure maintains sufficient rigidity through its construction

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The invention introduces flexibility to the blade by allowing it to dynamically adapt to the surface being finished. The curved bottom profile enables the blade to flex and conform during operation, preventing the rigid contact that causes trowel and chatter marks while maintaining operational stability

Inventive Principle:

Principle #15Dynamics

3Strength

If the blade is made from high carbon steel, then it provides strength and durability, but it leaves dark burn marks on the finished surface

Engineering Contradiction:

Improveblade strengthVSAvoiddark burn marks

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The invention replaces high carbon steel with a non-metallic material such as polymer or composite that does not leave dark burn marks on the finished surface. The blade is designed to be replaced periodically, making the material choice secondary to achieving the mark-free finish, effectively treating the blade as a consumable item

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

4Ease of manufacture

If bolts or screws are installed from the bottom of the blade, then the blade can be assembled, but concrete accumulates in the voids and hardens, causing particles to fall out and scratch the surface

Engineering Contradiction:

Improveassembly capabilityVSAvoidsurface scratching from hardened concrete particles

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The invention extracts and removes the bottom-mounted bolt or screw assembly method. Instead, the blade uses threaded inserts embedded in the top surface or integrates mounting features that do not create bottom voids, eliminating the space where concrete could accumulate and harden to later scratch the finished surface

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention inverts the mounting approach by placing threaded inserts or mounting features on the top surface of the blade rather than installing bolts from the bottom. This reversal eliminates the bottom voids that trap concrete, allowing proper drainage and preventing hardened particle formation

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS11473317B2Non-rusting and flush bottom polymer power trowel blade

Publication Date: 2022.10.18 SNYDER JEFFREY LYNN

AI summary

A power trowel blade that is made of non-rusting solid component material for use with a power trowel apparatus. The trowel blade include a mounting surface and an oppositely facing finishing surface. The finishing surface is flush and free of voids or protrusions. The flush finishing surface prevents surface material being collected as the trowel blade is used to finish surfaces to a hard finish.