Milling Pick Shank Diameter to Disk Thickness Ratio
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Solution Overview
Problem
Milling picks face issues with break resistance due to high bending stresses in the transition area between the pick head and shank, leading to potential shaft fracture, especially in road construction applications where increased loads exacerbate wear and penetration of waste material into the toolholder.
Innovation Solution
The ratio of the pick shank diameter in the cut-out area to the wear-protection disk thickness is optimized to be between 1.5 to 3.75, with a preferred range of 2 to 3, allowing for a shorter pick head and thicker wear-protection disk, reducing bending stresses and incorporating recesses and a conical centering attachment for improved guidance and particle removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pick head length is increased to maintain the same absolute projection of the free end of the pick tip, then the cutting performance is improved, but the bending stresses in the transition area increase leading to higher risk of shaft fracture
Solution Approach 1:
The patent applies parameter changes by optimizing the ratio of pick shank diameter to wear-protection disk thickness within the range 1.5 to 3.75. This dimensional parameter optimization allows the pick head length to be shortened while maintaining adequate projection, thereby reducing bending stresses in the transition area without compromising cutting performance. The optimized ratio distributes mechanical loads more effectively through the pick shank and wear-protection disk structure.
Solution Approach 2:
The pick is segmented into distinct functional components: the pick tip for cutting, the pick head for structural support, the wear-protection disk for load distribution, and the pick shank for transmission. This segmentation allows each component to be optimized independently - the pick head can be shortened while the wear-protection disk thickness is increased to compensate, maintaining overall structural integrity and reducing bending stresses at the transition area.
2Strength
If the wear-protection disk thickness is increased to reduce bending stresses, then the break resistance is improved, but the pick head length must be shortened which may affect cutting performance
Solution Approach 1:
The patent optimizes the dimensional parameters by establishing a specific ratio range (1.5 to 3.75) between the pick shank diameter and wear-protection disk thickness. This parameter optimization enables simultaneous achievement of increased disk thickness for stress reduction and maintained pick head length for cutting performance, as the ratio constraint ensures proportional scaling of both dimensions.
Solution Approach 2:
The pick employs composite construction with different materials for different components: hard material for the pick tip, appropriate strength material for the pick head and shank, and wear-resistant material for the wear-protection disk. This composite material approach allows each component to be optimized for its specific function - the thicker wear-protection disk can be made from wear-resistant material while the pick head maintains adequate length through material selection, achieving both break resistance and cutting performance.
3Ease of operation
If the axial play is increased to allow for larger bits, then the ease of operation is improved, but the wear-protection disk is no longer laterally guided resulting in increased wear
Solution Approach 1:
The lateral guidance function is segmented from the axial play function. The centering attachment provides dedicated lateral guidance through its geometric constraint, while the axial play is maintained through the cut-out design. This functional segmentation allows the system to accommodate larger bits with increased axial play while maintaining reliable lateral guidance and reducing wear through the dedicated centering mechanism.
Data Source
AI summary
The invention relates to a milling pick, in particular a round pick having a pick head (40), which has a pick tip (30) made of a hard material as a cutting element, wherein furthermore a pick shank (10) is provided, which is coupled directly or indirectly to the pick head (40), wherein a wear-protection disk (20) is provided, the cut-out of which, in particular a drilled hole, is pushed onto the pick shank (10),wherein the wear-protection disk (20) has, on its side facing the pick head (40), a counterface (23), which is designed to come into contact with a bearing surface (41) of the pick head (40), wherein the wear protection disk has, facing away from the counterface (23), an underside support surface (21), which is preferably parallel to the counterface (23), and wherein a disk thickness (d) is formed between the counterface (23) and the support surface (21),is characterized in that the ratio of the diameter of the pick shank (10) located in the area of the cut-out (25) to the thickness of the disk (d) being in the range from 1.5 to 3.75, preferably in the range from 2 to 3.