Driver Torque Transfer Symmetric Spline Profile
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Solution Overview
Problem
The existing drivers for rock drilling machines experience high load asymmetry and fatigue failure due to the asymmetric distribution of splines and polygonal profiles, leading to material deformation and fracture notches that impair their functionality.
Innovation Solution
The driver's polygonal profile and splines are redesigned to distribute loads symmetrically, with a convex polygonal shape and splines arranged to minimize contact pressure, creating chambers that prevent burrs from forming at the root radii, thereby reducing the risk of fatigue failure and increasing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the driver is provided with internal splines and an external polygonal profile for torque transfer, then the torque transfer capability is improved, but the asymmetric distribution of splines and polygonal profile corners leads to load asymmetry and fatigue failure
Solution Approach 1:
The patent applies asymmetry in reverse - it deliberately creates a symmetric arrangement where the number of spline teeth matches the number of polygonal profile sides (both equal to 3 or multiples thereof). This symmetric configuration ensures that loads are distributed evenly across all contact points during rotation, preventing the load asymmetry that occurs when spline count and polygonal sides differ. The symmetric arrangement eliminates preferential loading of specific corners or spline teeth, thereby preventing fatigue failure while maintaining high torque transfer capability.
2Power
If the driver operates under high torque loads (1000 Nm or more), then the power transmission capability is improved, but material deformation and fracture notches occur at the root radii of spline spaces
Solution Approach 1:
The patent applies local quality by specifically modifying the geometry at critical locations - the root radii of the spline spaces. By optimizing the root radius dimensions and ensuring proper fillet radii at these specific locations, the design locally enhances resistance to material deformation and fracture notches. This localized geometric optimization addresses the high stress concentrations that occur at these critical points during high torque operation, preventing fatigue failure without compromising the overall torque transmission capability of the driver.
3Duration of action of stationary object
If the driver design is modified to reduce load asymmetry and prevent fatigue failure, then the durability and lifespan of the driver are improved, but the complexity of the spline and polygonal profile arrangement increases
Solution Approach 1:
The patent applies parameter changes by establishing specific numerical relationships between the spline configuration and polygonal profile parameters. The key parameter change is setting the number of spline teeth equal to the number of polygonal sides (both to 3 or multiples thereof), and optimizing the root radius dimensions to specific values or ranges. These parameter changes create a standardized design approach that achieves symmetric load distribution and improved durability without excessive complexity, as the relationships are defined by simple numerical ratios rather than complex geometric arrangements.
Data Source
AI summary
A driver (3) for the transfer of torque and rotation from a rotation chuck (5) to a drill steel (2), whereby the cross-section of the driver (3) is limited outwards by curves, in particular by arcs, united to form a closed FIG. 6 that can be approximately described as a polygon, and limited inwards by splines (4). The FIG. 6 comprises four sides (7) and four corners (8). The splines (4) comprise a number of spline teeth (10), the number of which is divisible by four.