Resin and Metal Composite Lawn Mower Ground Slide Guide

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Solution Overview

Problem

Existing grass cutters with metal ground surface slide guides suffer from instability and premature wear due to their weight and uniform thickness, leading to inefficient grass cutting and short service life.

Innovation Solution

A ground surface slide guide composed of a lightweight synthetic resin body with a metal hub, featuring a tubular design with a thicker lower end for enhanced stability and wear resistance, along with a cutting string attachment option for safe obstacle navigation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a metal-made ground surface slide guide is used, then the slide guide has sufficient strength, but the weight increases and stability with respect to the ground surface decreases

Engineering Contradiction:
Improvestrength of slide guideVSAvoidweight of slide guide
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The slide guide is constructed as a composite structure combining a metal hub (providing strength and rigidity) with a resin body (providing lightweight coverage). This composite design allows the metal component to bear mechanical loads while the resin material reduces overall weight and increases the diameter for enhanced ground stability.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The slide guide is divided into functionally distinct segments: a metal hub for structural integrity and attachment functions, and a resin body for weight reduction and ground contact. This segmentation allows each material to be optimized for its specific function, resolving the contradiction between strength and weight.

Inventive Principle:
Principle #1Segmentation

2Ease of manufacture

If a metal-made ground surface slide guide with uniform thickness is used, then the manufacturing is simple, but the ground contact location becomes worn early resulting in short service life

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidservice life of slide guide
Core Design Contradiction:
Ease of manufactureVSDuration of action of stationary object

Solution Approach 1:

The resin body incorporates a localized thickened portion at the ground contact area, while other portions maintain standard thickness. This local quality enhancement provides extra wear resistance precisely where the ground contact occurs, extending service life without significantly increasing overall complexity or material usage.

Inventive Principle:
Principle #3Local quality

3Weight of moving object

If a small diameter ground surface slide guide is used, then the weight is reduced, but the stability with respect to the ground surface becomes insufficient

Engineering Contradiction:
Improveweight of slide guideVSAvoidstability with respect to ground surface
Core Design Contradiction:
Weight of moving objectVSStability of the object's composition

Solution Approach 1:

The combination of metal hub and resin body creates a composite structure where the resin material enables a larger outer diameter without proportionally increasing weight. This larger diameter provides better ground contact stability while the resin's lower density keeps the overall weight manageable.

Inventive Principle:
Principle #40Composite materials

Data Source

PatentEP1997364B1Ground surface slide guide of lawn mower and lawn mower
Publication Date: 2013.05.08 KK KITAMURA SEISAKUSHO
  • EP1997364B1 patent drawingFigure 1~4
  • EP1997364B1 patent drawingFigure 5~8
  • EP1997364B1 patent drawingFigure 9(A)~10

AI summary

A ground surface slide guide attached to a grass cutter is of light weight and has a large diameter and superior durability, enabling comfortable grass cutting work. The ground surface slide guide has a resin body made of synthetic resin, and a metal hub integrally coupled thereto to rotate together. The resin body is composed of a tubular body and a flange extending upward to the outside from the entire periphery of the lower end of the tubular body and covering the lower surface of the rotary blade. A blade retaining ring pressed against the lower surface of the rotary blade is formed on the outer periphery of the hub, and the blade retaining ring is exposed to the upper end surface of the tubular body. The hub is attached to a drive shaft by a fastener, and the rotary blade is clamped between a blade rest and a blade retaining ring. The lower end of the tubular body serves as a ground contact surface. The metal hub is integrally coupled to the resin body to rotate together. The overall weight is reduced by the resin body, and the lower surface of the rotary blade can be covered over a wide range, thereby improving stability with respect to the surface of the ground. In addition, since wear resistance performance is enhanced by making the thickness of the lower end of the tubular body serving as the contact surface that contacts the ground greater than the thickness of the flange, the durability of the ground surface slide guide can be improved.