Movable Riving Knife for Circular Saw Safety and Flexibility

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Solution Overview

Problem

The disassembly and assembly of riving knives on circular saws are time-consuming and costly, and the absence of a riving knife during certain operations increases the risk of accidents due to the need for manual handling and the likelihood of operators neglecting to reattach it promptly.

Innovation Solution

A circular saw design that allows the riving knife to be manually or automatically moved between two positions relative to the saw blade's axis of rotation, enabling it to be easily repositioned without disassembly, with a holding mechanism to secure it in place and sensors to automate its return to the safe position when not interfering with operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the riving knife is disassembled and reassembled for different operations, then the saw can perform both guided and unguided operations, but the process is time-consuming and costly

Engineering Contradiction:
Improveoperation flexibilityVSAvoidknife management time
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The riving knife is designed to be movable rather than fixed, allowing it to transition between positions. The knife can be retracted to allow unguided operations (like plunge cuts) and extended to provide guidance for standard operations, eliminating the need for complete disassembly and reassembly.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The riving knife is divided into multiple segments or sections that can be independently positioned. This segmentation allows the knife to be adjusted to different configurations for different operations without requiring complete removal from the saw.

Inventive Principle:
Principle #1Segmentation

2Adaptability or versatility

If the riving knife is manually handled for repositioning, then the saw can adapt to different operations, but the risk of accidents increases due to operator neglect

Engineering Contradiction:
Improveoperation adaptabilityVSAvoidsafety
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The riving knife system incorporates automatic sensing and actuation mechanisms that detect when the knife should be repositioned and automatically perform the repositioning action. This self-service capability eliminates reliance on operator memory and attention, ensuring the knife is correctly positioned for each operation.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system uses sensors to detect the presence of workpieces and the type of operation being performed, providing feedback to the control system. Based on this feedback, the system automatically adjusts the riving knife position, creating a closed-loop control system that enhances safety.

Inventive Principle:
Principle #23Feedback

3Reliability

If the riving knife is kept in a fixed position, then safety is improved, but the ability to perform certain operations like plunge cuts is lost

Engineering Contradiction:
Improveoperator protectionVSAvoidoperation capability
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The riving knife transitions from a static, fixed-position component to a dynamic, movable component that can automatically adjust its position based on operational requirements. This allows the knife to provide protection during standard operations while being retracted during operations like plunge cuts where it would be in the way.

Inventive Principle:
Principle #15Dynamics

4Loss of time

If the riving knife is automatically repositioned, then time is saved and safety is improved, but the device complexity increases

Engineering Contradiction:
Improveknife repositioning timeVSAvoidautomation system complexity
Core Design Contradiction:
Loss of timeVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical disassembly and reassembly mechanisms with a simpler automated positioning system. Instead of requiring multiple fasteners and manual operations, the system uses sensors and automated actuators to reposition the knife, reducing overall mechanical complexity while achieving the same functional goals.

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

Data Source

PatentEP2234779B1Circular saw
Publication Date: 2011.09.07 ROBERT BOSCH GMBH
  • EP2234779B1 patent drawingFigure 1a~1c
  • EP2234779B1 patent drawingFigure 2~4
  • EP2234779B1 patent drawingFigure 5~7

AI summary

Circular saw (30; 40; 50; 60; 65; 70; 80; 90), comprising a saw blade (36) driven in rotation about a pivot axis (37) and at least one first splitting wedge (38), wherein the circular saw (30; 40; 50; 60; 65; 70; 80; 90) is configured such that the first splitting wedge (38) can be moved relative to the pivot axis (37) of the saw blade (36).