Rotary Tool Insertion End Torque Transmission Design
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Solution Overview
Problem
Conventional insertion ends for rotary or percussively driven tools face issues with damage and wear due to high torque transmission and poor impact pulse transmission, especially at larger drill diameters, leading to breakages and excessive wear in tool holders.
Innovation Solution
The insertion end design features a maximum guide diameter with axially closed locking grooves and extended rotary driving grooves that provide tangential force contact surfaces, allowing for higher torque transmission with reduced stress on critical zones and improved impact pulse behavior, featuring multiple rotary driving grooves and a distinct separation of functional zones for enhanced torsional strength and manufacturing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the guide diameter is increased to accommodate larger drill diameters (30 mm), then the torque transmission capability is improved, but the insertion end becomes more prone to breakage and damage at the locking groove zone
Solution Approach 1:
The insertion end is divided into distinct functional zones: a first zone with locking grooves for axial positioning and a second zone with rotary driving grooves for torque transmission. This segmentation allows each zone to be optimized for its specific function, preventing stress concentration at the locking groove while maintaining high torque capability.
Solution Approach 2:
Different regions of the insertion end are given different structural characteristics. The first zone has locking grooves with specific cross-sectional geometry optimized for axial retention, while the second zone has rotary driving grooves with geometry optimized for torsional strength and torque transmission. This local differentiation resolves the contradiction between torque transmission and breakage resistance.
2Power
If the guide diameter is increased to 18 mm for higher power drills, then the torque transmission is improved, but the impact pulse transmission deteriorates at smaller drill diameters (14 mm)
Solution Approach 1:
The cross-sectional geometry parameters of the grooves are specifically optimized to balance torque transmission and impact pulse transmission. The locking grooves and rotary driving grooves have dimensions and shapes that allow efficient force transmission while maintaining structural integrity for impact loads, enabling the same insertion end to perform well across different power classes.
3Device complexity
If the locking groove cross-section is reduced in the axial region, then the device complexity is reduced, but the fatigue strength and breaking strength are limited
Solution Approach 1:
Instead of varying the cross-section in the axial dimension (which would increase complexity), the solution moves to the radial dimension by creating distinct functional zones with different groove configurations. The locking grooves and rotary driving grooves are arranged in separate radial zones, achieving both simplicity and high strength through spatial differentiation rather than axial variation.
Data Source
AI summary
An insertion end of a tool is driven along an axis at least partially rotary or percussively, which extends along the axis within a maximum guide diameter. At least one longitudinally closed locking groove and rotary driving groove is longitudinally closed at a longitudinal locking end towards the free leading end. The rotary driving groove has a groove width with at least one tangential force contact surface. At least two rotary driving grooves have a length of at least three times that of the guide diameter are arranged on the tool-side ahead of the longitudinal locking end, and have a contact length at least 1.5 times the guide diameter configured to be one fifth of the guide diameter.