Scarfing Machine Disc Cutter Tilt Angle Optimization

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Solution Overview

Problem

Existing scarfing machines create concave arcs in the scarf surface, leading to potential double cutting and poor joining of scarf surfaces due to excessive curvature, which can result in partial contact and inadequate adhesive retention.

Innovation Solution

A scarfing machine with a disc cutter tilted at a calculated second tilt angle, angled downward to prevent re-contact with the machined surface, and positioned to apply cutting force in the board thickness direction, reducing deformations and ensuring an appropriate arc concavity for effective joining.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the heeling angle of the circular saw is increased to prevent double cutting, then the reliability of preventing blade re-contact is improved, but the curvature of the concave arc in the scarf surface increases excessively, leading to poor joining quality

Engineering Contradiction:
Improveprevention of double cuttingVSAvoidjoining quality of scarf surface
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by precisely controlling the heeling angle within a specific range (0° to 10°) rather than using a large angle. This optimized parameter range prevents double cutting while limiting the concave arc curvature to an acceptable level, thereby resolving the contradiction between reliability of double-cutting prevention and manufacturing precision of joining quality

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces dynamic adjustment of the heeling angle based on the specific machining conditions, board thickness, and desired scarf ratio. The heeling angle is not fixed but adapted to achieve the optimal balance between preventing blade re-contact and maintaining appropriate arc curvature for good joining

Inventive Principle:
Principle #15Dynamics

2Reliability

If a heeling angle is applied to prevent blade re-contact with the scarf surface, then double cutting is prevented, but a concave arc is created in the scarf surface which may cause partial contact during joining

Engineering Contradiction:
Improveprevention of blade re-contactVSAvoidconcave arc curvature of scarf surface
Core Design Contradiction:
ReliabilityVSShape

Solution Approach 1:

The patent changes the heeling angle parameter from a large value to a small optimized range (0° to 10°), which modifies the shape of the scarf surface to have an appropriate concave arc rather than an excessive one. This ensures the surface retains the necessary curvature for adhesive retention while avoiding excessive concavity that would cause partial contact during joining

Inventive Principle:
Principle #35Parameter changes

3Reliability

If the heeling angle is increased to ensure blades do not re-contact the scarf surface, then double cutting prevention is improved, but the arc concavity becomes too curved, reducing adhesive retention capability

Engineering Contradiction:
Improveprevention of double cuttingVSAvoidadhesive retention capability
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent optimizes the heeling angle parameter to fall within 0° to 10°, which creates an appropriate arc concavity that maintains adhesive retention capability. This parameter optimization prevents both double cutting and excessive curvature, thereby preserving the pocket effect needed for good adhesive bonding

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4279235B1Scarfing machine and method of scarfing
Publication Date: 2026.03.04 MEINAN MASCH WORKS INC
  • EP4279235B1 patent drawingFigure 1
  • EP4279235B1 patent drawingFigure 2
  • EP4279235B1 patent drawingFigure 3

AI summary

Scarf faces 92a, 92b are machined at a heeling angle θ2 on a veneer 90 by adjusting the heeling angle θ2 for a desired camber h using the following Equation (1): h=R2•sin θ2−sin 2θ2•R2−t2(1+i2)4 With the configuration, double cutting of the veneer 90 by a circular saw 20 can be effectively prevented. Since the camber h is set desirably, the risk can be reduced that the scarf faces 92a, 92b only partially join each other, and a space can be secured to retain an adhesive Ad between arc concavities 91, 91. Thus, when the veneers 90 are joined together at the scarf faces 92a, 92b, the adhesive Ad is unlikely to seep out onto the surfaces of the veneers 90. As a result, the scarf faces 92a, 92b can be properly joined together.