Bore Machining Tool With Support Collar for Stable Deep Drilling
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Solution Overview
Problem
Existing tools for machining bores face challenges in maintaining accuracy and preventing tool displacement due to asymmetrical forces, especially when drilling through cavities or exiting on an inclined surface, leading to increased friction, wear, and risk of tool breakage.
Innovation Solution
The tool incorporates a support collar adjacent to each secondary cutting edge, extending at least 170° in the circumferential direction, which is axially set back from the tool end face, providing stabilizing guide properties and supporting resulting forces, even when the tool exits at an angle, thus reducing friction and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If guide chamfers are added to stabilize the tool against displacement, then hole accuracy and roundness are improved, but friction and wear on the guide chamfers increase, leading to higher torques and risk of tool breakage
Solution Approach 1:
The invention transitions from conventional guide chamfers (extending radially from the cutting edge) to a support collar (extending axially behind the cutting edge). This dimensional change in the guide structure's orientation allows support to be provided in the axial direction rather than radially, fundamentally altering how guidance and support forces are applied to the tool during machining.
Solution Approach 2:
The support collar acts as an intermediary element between the cutting edge and the bore wall. Instead of the guide chamfers directly contacting the bore wall and experiencing high friction, the support collar provides indirect support by bearing against the bore wall at a location that reduces direct frictional engagement while maintaining tool stability and guidance.
2Manufacturing precision
If additional guide chamfers are used to improve roundness and straightness, then hole accuracy is improved, but the guide chamfers prevent subsequent cutting edges from compensating for displacement, causing the tool to jam in the hole
Solution Approach 1:
By positioning the support collar axially behind the cutting edge rather than extending radially outward, the invention creates spatial separation between the guidance function and the cutting function. This allows the cutting edges to move laterally to compensate for displacement while the support collar maintains axial stability and guidance, resolving the conflict between guidance rigidity and cutting flexibility.
Solution Approach 2:
The invention separates the guidance function from the cutting function by placing the support collar as a distinct element behind the cutting edge. This segmentation allows each element to perform its specific function independently - the cutting edges handle material removal and can compensate for displacement, while the support collar provides stable guidance without interfering with the cutting edges' ability to self-correct.
3Manufacturing precision
If the tool exits the bore on an inclined surface, then the cut is interrupted, but guide chamfers lack bore wall support and cannot contribute to improvement, while actually preventing subsequent cutting edges from compensating for displacement
Solution Approach 1:
The support collar extends axially behind the cutting edge into the uninterrupted cylindrical portion of the bore, providing guidance support in the axial direction even when the cutting edge operates in the interrupted inclined portion. This dimensional extension ensures continuous support regardless of the cutting phase.
Solution Approach 2:
The support collar is positioned to provide guidance support in advance of the cutting edge during the interrupted cut phase. By having the support collar already engaged with the bore wall in the uninterrupted section, the tool maintains stability and guidance before the cutting edge re-engages the material, preventing displacement accumulation.
Data Source
AI summary
The invention relates to a tool for the machining of bores. The tool includes a tool body with a centre axis and a tool end face. At least two secondary cutting edges are formed on the tool body; each secondary cutting edge of the at least two secondary cutting edges, starting from a cutting corner corresponding with the secondary cutting edge on the tool end face, extending in the direction of the centre axis towards a shaft end of the tool in a helical manner with a specific twist pitch. A support collar adjoins each of the secondary cutting edges at a distance, measured in the direction of the centre axis, of at least 0.18 times up to at most 0.28 times the specific twist pitch from the corresponding cutting corner, which support collar extends in the circumferential direction at least up to 1700 to the corresponding cutting corner.