Shortened Shank Bit Holder with Differential Angles
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing bit assemblies in road milling and mining equipment face challenges with limited rear access, making it difficult to remove and replace bit assemblies efficiently, especially in densely packed configurations.
Innovation Solution
A bit holder design with a shortened shank and differential shank/base block bore angles, featuring a slot and increased diameters, provides improved retention and access by redistributing interference forces and increasing radial and circumferential forces, allowing for easier extraction and replacement of bit assemblies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the shank length is reduced to improve rear access, then ease of operation is improved, but retention force between shank and base block bore deteriorates
Solution Approach 1:
The shank is designed with non-uniform diameter along its length, featuring a reduced diameter portion and enlarged diameter portions at specific locations. This local variation in geometry concentrates interference forces at the enlarged portions while maintaining overall shorter length, thereby improving rear access without sacrificing retention force.
Solution Approach 2:
The shank geometry parameters are optimized by creating differential diameter sections. The reduced diameter portion allows for shorter overall length while enlarged diameter portions provide concentrated interference fit zones that maintain adequate retention force despite the reduced shank length.
2Productivity
If bit assemblies are positioned closer together axially to improve material removal efficiency, then productivity is improved, but rear access deteriorates
Solution Approach 1:
The shank is segmented into distinct diameter portions (reduced diameter portion and enlarged diameter portions) along its length. This segmentation allows the bit holder to maintain compact overall dimensions for closer axial positioning while the enlarged portions provide sufficient interference fit for retention, thereby enabling closer bit spacing without compromising access.
3Reliability
If interference forces are concentrated to improve retention, then reliability is improved, but access to rear of base block deteriorates
Solution Approach 1:
Interference forces are concentrated at localized enlarged diameter portions of the shank rather than being distributed along the entire shank length. This local concentration of retention force provides reliable mounting while the reduced diameter portions and overall shorter length improve access to the rear of the base block.
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
The design reduces downtime by enhancing access to bit assemblies, enabling more efficient removal and replacement, particularly in densely packed configurations, and allows for closer axial orientation of bit tips for improved material removal efficiency.
Implementation Method 1
the shank may be driven into a bore in the base block and the distal end of the shank is compressed radially with a sufficient radial force between the bit holder shank and the base block bore to maintain the bit holder mounted on the base block during use
Data Source
AI summary
Improvements in previous bit assembly components including shortened slotted shanks and shortened base block bore receiving portions disclose relationships between shank differential interference portions and the corresponding base block bores. Changes in the differences in interference angles lead to changes in slot width, length and steel hardnesses in order to provide necessary retaining forces between the shank and base block bore.