Boring Tool Secondary Blade Overshoot Support
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing drilling tools lack sufficient support during the drilling process, leading to loss of guiding function as the main cutting edge emerges from the hole, resulting in incomplete centering and surface refinement in the borehole.
Innovation Solution
The drilling tool incorporates a secondary cutting edge with a support section having a larger radius of rotation than the main cutting edge, providing support during drilling and smoothing the bore wall by extending beyond the cutting circle radius, with the support part arranged opposite to the rotation direction and elongated in the feed direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If guide chamfers are provided on cutting inserts for centering in a pre-formed drill hole, then the drilling tool can be centered in the hole, but the guide chamfers are not sufficient for using the drill as a boring tool during the drilling process
Solution Approach 1:
The support section is arranged on the secondary cutting edge with a larger radius of rotation than the main cutting edge, so that it makes contact with the bore wall before the main cutting edge emerges from the hole. This preliminary contact maintains the guiding function throughout the drilling process, preventing the loss of centering that occurs with conventional guide chamfers alone.
2Reliability
If support elements are arranged at a distance from the cutting insert on the base body, then support is provided when the main cutting edge emerges from the hole, but the supporting elements only become effective after drilling through, not during the drilling process
Solution Approach 1:
The support section is integrated into the secondary cutting edge geometry rather than being a separate element on the base body. This positioning ensures that the support function begins immediately when the tool engages the workpiece, eliminating the time gap where no support is available during the drilling process.
Solution Approach 2:
The support function is merged with the cutting edge structure by integrating the support section into the secondary cutting edge. This combination ensures that support is provided continuously during drilling, rather than relying on separate support elements that only engage after drilling through.
3Manufacturing precision
If the support section has a larger radius of rotation than the main cutting edge, then the drilling tool is supported during the drilling process and the workpiece surface is smoothed, but the device complexity increases
Solution Approach 1:
The secondary cutting edge is designed to serve dual functions: cutting and support. By forming the support section as part of the secondary cutting edge geometry, the tool achieves both surface refinement and continuous support without adding separate components, thereby limiting the increase in device complexity.
Data Source
Figure 1a~1b
Figure 1c~1d
Figure 2a~2b
AI summary
The invention relates to a rotating cutting tool, in particular a boring tool for use in machine tools. The cutting tool comprises at least one cutting insert (16'), designed as an indexable insert, that has an active main blade (26) located near a corner (25) of the insert, the outer end (28) of said blade defining a circular flight path radius (R) as the blade rotates, said blade penetrating into a work piece (32) at a pre-determined cutting depth (t) near a pre-formed round hole (30). Also provided is a secondary blade (36) that is disposed opposite to an advancing direction (34) and that aligns with the outermost end (28) of the main blade (26), the entire length of said blade having a smaller radius than the circular flight path radius (R) of the main blade (26), wherein a secondary blade free surface (38) aligns with the secondary blade opposite to the direction of rotation (37). A unique characteristic of the invention is that the secondary blade free surface (38) comprises a support part (40) disposed at a distance from the secondary blade (36), the peripheral radius of said part being larger than the circular flight path radius R of the active main blade (26) by an overshoot amount (Y).