Stepped Base Material Geometry for Crack-Resistant Hard Sintered Tools
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hard sintered materials used in cutting tools face issues with thermal stress-induced cracks due to significant differences in the coefficient of linear expansion between the base material and the cylinder portion, leading to potential cracks during brazing.
Innovation Solution
A base material with a multi-stage columnar shape featuring a smaller-diameter and larger-diameter portion, along with first and second inclined portions, is used to minimize the volume of the base material and maximize the cylinder portion, reducing thermal stress and enhancing bonding strength by increasing contact area and releasing stress perpendicular to the inclined portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the base material volume is increased to ensure structural stability, then the structural stability is improved, but the thermal stress during brazing increases leading to crack formation
Solution Approach 1:
The base material is divided into multiple diameter portions (first diameter portion and second diameter portion) with different cross-sectional areas. This segmentation allows the structure to have both stability (through the larger second diameter portion) and reduced thermal stress (through the smaller first diameter portion at the interface), resolving the contradiction between structural stability and thermal stress reduction.
2Object-affected harmful factors
If the cylinder portion volume is increased to reduce thermal stress, then the thermal stress is reduced, but the base material volume decreases affecting structural integrity
Solution Approach 1:
The base material is designed with non-uniform local quality through having different diameter portions. The first diameter portion has a smaller cross-sectional area at the interface region to reduce thermal stress, while the second diameter portion has a larger cross-sectional area to maintain overall structural integrity. This local variation in geometry allows simultaneous achievement of reduced thermal stress and maintained structural integrity.
3Strength
If the contact area between base material and cylinder portion is increased to enhance bonding strength, then the bonding strength is improved, but the base material volume increases leading to more thermal stress
Solution Approach 1:
The interface between base material and cylinder portion is designed with an inclined surface rather than a simple axial cross-section. This introduces a radial dimension to the contact area, allowing the bonding interface to extend in multiple directions. The inclined surface increases the effective contact area for bonding while the overall volume of base material can be controlled, thus enhancing bonding strength without proportionally increasing thermal stress.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively reduces thermal stress during brazing, preventing cracks in the hard sintered material and ensuring stable manufacturing of cutting tools.
Implementation Method 1
a coefficient of linear expansion (coefficient of thermal expansion) of the base material and a coefficient of linear expansion of the cylinder portion are significantly different from each other... Therefore, when the hard sintered material and the shank are brazed, cracks may occur near an interface between the cylinder portion and the base material due to thermal stress
Data Source
AI summary
A base material for a hard sintered material has a multi-stage columnar shape having a central axis and extending in an axial direction of the central axis. The base material includes a smaller-diameter portion, a larger-diameter portion, a base material end surface located between a one end portion in the axial direction of an outer peripheral surface of the larger-diameter portion and the other end portion in the axial direction of the smaller-diameter portion, and facing toward the one end portion in the axial direction, and a first inclined portion disposed in at least a portion in a circumferential direction of an annular corner portion to which an outer peripheral surface of the larger-diameter portion and the base material end surface are connected. The first inclined portion is located inward in a radial direction toward the one end portion in the axial direction.