Thin Circular Saw Blade Geometry for Longer Cordless Runtime

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Solution Overview

Problem

Cordless plunge saws, circular saws, table saws, and miter saws require circular saw blades optimized to enhance runtime, as existing blades do not efficiently utilize battery power, leading to shorter cutting sessions.

Innovation Solution

The development of circular saw blades with a specific geometry, including a thickness of 0.75 mm to 0.88 mm, a hook angle of 20° to 25°, a clearance angle of 10° to 14°, and an alternating top bevel plus raker (ATB+R) pattern for the cutting inserts, which improves battery runtime by at least 40% compared to standard carbide-tipped blades.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If standard carbide-tipped blades with conventional geometry are used, then cutting capability is maintained, but battery runtime is reduced

Engineering Contradiction:
Improvebattery runtimeVSAvoidnumber of cuts per battery charge
Core Design Contradiction:
Duration of action of moving objectVSProductivity

Solution Approach 1:

The patent applies parameter changes by optimizing the plate thickness to 0.75mm-0.88mm (thinner than conventional blades), setting the hook angle to 20°-25° (steeper than standard), and configuring the clearance angle to 10°-14°. These parameter modifications reduce the blade's moment of inertia and optimize cutting geometry, enabling faster cutting speeds that extend battery runtime while maintaining productive cutting output.

Inventive Principle:
Principle #35Parameter changes

2Duration of action of moving object

If plate thickness is reduced to enhance runtime, then battery life is extended, but blade strength may be compromised

Engineering Contradiction:
Improvebattery runtimeVSAvoidblade strength
Core Design Contradiction:
Duration of action of moving objectVSStrength

Solution Approach 1:

The patent employs composite materials by constructing the blade with a thin plate body (0.75mm-0.88mm) made of high-strength steel, reinforced with carbide cutting inserts affixed to each tooth. This composite structure allows the plate to be thin enough for reduced moment of inertia and extended runtime, while the carbide inserts provide the necessary cutting edge strength and durability.

Inventive Principle:
Principle #40Composite materials

3Productivity

If hook angle is increased to improve cutting speed, then cutting efficiency increases, but blade stability may decrease

Engineering Contradiction:
Improvecutting speedVSAvoidblade stability
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The patent optimizes the hook angle to 20°-25°, which is steeper than conventional blades. This parameter change increases cutting aggressiveness and speed by allowing the cutting edge to engage the material more effectively. The thin plate design (0.75mm-0.88mm) compensates for potential stability issues by reducing overall blade mass and moment of inertia, allowing the blade to respond more dynamically to cutting forces while maintaining stability through proper balance and the stabilizing effect of the ATB+R insert pattern.

Inventive Principle:
Principle #35Parameter changes

4Productivity

If alternating top bevel plus raker (ATB+R) pattern is used, then cutting performance is enhanced, but manufacturing complexity increases

Engineering Contradiction:
Improvecutting performanceVSAvoidmanufacturing complexity
Core Design Contradiction:
ProductivityVSEase of manufacture

Solution Approach 1:

The patent applies segmentation by dividing the cutting edge into alternating segments: teeth with top bevel (ATB) geometry and raker (R) inserts without top bevel. This segmentation creates the ATB+R pattern that enhances cutting performance by alternating between aggressive cutting teeth and material-ejecting rakers. The segmentation approach allows each insert type to be manufactured separately using standardized carbide insert processes, then assembled in the alternating pattern during blade manufacturing, balancing performance enhancement with manufacturing feasibility.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3162483B1Circular saw blades
Publication Date: 2021.08.18 BLACK & DECKER CORP
  • EP3162483B1 patent drawingFigure 1
  • EP3162483B1 patent drawingFigure 2
  • EP3162483B1 patent drawingFigure 3

AI summary

A circular saw blade (10) includes a circular plate (12) having a diameter D, a thickness T, a left face (14), a right face (15), a peripheral rim (18), and a central opening (16) couplable to a powered saw. A plurality of alternating teeth (20) and gullets (22) are disposed about the peripheral rim, each tooth having a front face (24) facing generally toward an adjacent gullet (22a) in the cutting direction and a recess (30) defined in the front face. A plurality of cutting inserts (32) are affixed in the recesses in the teeth. Each insert has rake face (34) facing generally toward the adjacent gullet in the cutting direction, a relief face (36) extending generally toward the adjacent top face (28), and a cutting edge (38) at a junction between the relief face and the rake face. Each rake face is disposed at a hook angle α between the rake face and a radius of the circular plate intersecting the cutting edge. The relief faces include a plurality of unbeveled relief faces (36U), left-beveled relief faces (36L) beveled toward the left face of the circular plate, and a plurality of right-beveled relief faces (36R) beveled toward the right faces of the circular plate, arranged in an alternating top bevel with raker (ATB+R) bevel pattern.