Excavator Tooth Cavity Geometry for Pin Retention and Wear Resistance
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Solution Overview
Problem
Existing tooth designs for working machines like excavators face challenges in balancing penetration capability, strength, and material efficiency, with couplings often experiencing pin breakage or deformation, and requiring complex removal procedures.
Innovation Solution
A tooth design featuring a cavity with specific inner wall geometry and contact surfaces that distribute forces evenly, reducing stress and allowing for secure attachment and easy removal without the need for hammering, using a pin that extends through aligned holes in the tooth and adaptor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the tooth is designed with sufficient length and slimness for penetration, then penetration capability is improved, but strength and robustness deteriorate
Solution Approach 1:
The tooth is designed with varying cross-sectional dimensions along its length, with the attachment portion having greater thickness and the tip portion being thinner. This local differentiation allows the tooth to have sufficient length for penetration while maintaining strength where needed through optimized material distribution.
Solution Approach 2:
The tooth is constructed from high-strength wear-resistant steel material that provides both the necessary strength and penetration capability. The material properties are optimized to achieve the required mechanical performance without requiring excessive dimensions.
2Strength
If the tooth design is optimized for strength and penetration, then durability is improved, but material usage increases, raising cost
Solution Approach 1:
The tooth features non-uniform cross-sectional dimensions with the attachment portion having greater thickness for strength while the working portion tapers to reduce material usage. This localized optimization maintains necessary strength while minimizing overall material consumption.
Solution Approach 2:
The cross-sectional dimensions of the tooth are optimized through parameter adjustment, with specific thickness values (e.g., 20-40mm at attachment portion, 10-20mm at tip portion) that balance strength requirements with material efficiency and cost considerations.
3Strength
If the coupling uses a pin through holes for secure attachment, then coupling strength is improved, but pin breakage and deformation risk increases
Solution Approach 1:
The attachment pin is designed with a tapered shape that facilitates easy insertion into the aligned holes of the tooth and adaptor before full loading occurs. This preliminary design consideration prevents forcing the pin, reducing the risk of deformation or breakage during installation.
Solution Approach 2:
The attachment pin features variable cross-sectional dimensions with a smaller end diameter for insertion and a larger base diameter for strength. This parameter variation allows the pin to be inserted easily while maintaining sufficient strength to resist breakage under operational loads.
4Strength
If the pin is deformed under load, then coupling strength is maintained, but removal complexity increases requiring hammering
Solution Approach 1:
The coupling system is designed to allow controlled deformation of the attachment pin under operational loads, with the tapered geometry enabling the pin to yield slightly and lock the tooth in place. During removal, reverse forces are applied to undo this deformation and facilitate extraction without hammering.
Solution Approach 2:
The attachment pin's tapered design allows it to self-lock under load through elastic deformation, maintaining coupling strength without additional locking mechanisms. During removal, the same deformation characteristics enable easy extraction by applying reverse force, making the system self-servicing for both attachment and detachment.
Data Source
AI summary
The present disclosure relates to a tooth (1) for attachment to the lip of a bucket of a working machine, such as an excavator or loader, via an adaptor, the tooth (1) comprisinga cavity (103) for receiving a portion of said adaptor, the cavity (103) extending between said first and second opposed outer working surfaces (12, 14) from an open end (104), at said attachment end of the tooth, to a bottom end (105); the cavity (103) being delimited by an inner wall (102); said inner wall (102) comprising first and second internally facing inner walls (106, 107), being the internal surfaces associated with said first outer working surface and said second working outer surface (12,14), respectively, and opposing side walls (108), interconnecting said first and second inner walls (106, 107), the cavity defining a back portion (BP) extending along the Y axis, the back portion being at least partially located between the plane spanned by the X and Z axis and the open end (104) of the cavity, a front portion (FP) extending along the Y axis, the front portion being located between the plane spanned by the X and Z axes and the bottom end (105) of the cavity; and a stepped portion (SP), interconnecting the back portion and the front portion; in the back portion, the first and second inner walls (106, 107), each comprises a pair of essentially planar back contact surfaces (130a, b; 140a,b), being separated by a back divider region (132, 142), extending beyond the pair of first contact surfaces.The disclosure also relates to an adaptor, and to the coupling between a tooth and an adaptor.