Ball Screw Nut Raceway Rolling After Pre-Machined Threading
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Solution Overview
Problem
Existing methods for producing ball raceways on workpieces, such as ball screw nuts, face inefficiencies in achieving precise final thread profiles with high surface quality and resistance to mechanical stresses, often requiring extensive machining and subsequent reworking to smooth out roughness peaks and enhance resilience.
Innovation Solution
A method involving the formation of a preliminary thread profile through machining, followed by thread rolling using a tool with a roller profile that rolls along the preliminary profile to create a final thread profile, allowing for cost-effective initial material removal and subsequent plastic deformation to achieve the desired ball raceway geometry, with optional hardening to enhance resilience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a preliminary thread profile is formed by machining and then reworked by thread rolling, then the surface quality and mechanical stress resistance are improved, but the manufacturing process complexity increases
Solution Approach 1:
A preliminary thread profile is first formed by machining with larger tolerances, then a thread rolling tool with a roller profile is used to roll along this preliminary profile to create the final high-precision thread profile. This two-stage approach allows the preliminary machining to remove most material with relaxed tolerances, while the subsequent rolling process achieves the required surface quality and dimensional precision.
Solution Approach 2:
The invention changes the physical state and geometric parameters of the workpiece surface through plastic deformation during thread rolling. The roller profile applies localized pressure to plastically deform the preliminary thread profile, smoothing roughness peaks and creating the final precise geometry. This parameter change from machining to plastic deformation improves surface quality without requiring extremely precise initial machining.
2Manufacturing precision
If extensive machining is performed to achieve precise thread profile, then the manufacturing precision is improved, but the productivity decreases
Solution Approach 1:
The preliminary thread profile is formed by machining with larger tolerances that are easier and faster to achieve, removing the majority of material. The subsequent thread rolling process then quickly refines this preliminary profile into the final precise geometry, significantly reducing the total machining time compared to attempting to achieve final precision through extensive machining alone.
Solution Approach 2:
The invention replaces extensive precision machining operations with a thread rolling process that uses plastic deformation to create the final thread profile. This mechanical substitution from cutting-based machining to deformation-based rolling increases productivity while maintaining or improving manufacturing precision, as rolling can be performed faster and with less tool wear.
3Manufacturing precision
If high torques are applied during thread rolling to generate final thread profile, then the manufacturing precision is improved, but the use of energy increases
Solution Approach 1:
By pre-forming the thread profile through machining, the material is already positioned close to its final geometry. This preliminary action reduces the amount of plastic deformation required during thread rolling, thereby reducing the torques needed to achieve the final precise thread profile compared to forming the entire thread profile through rolling alone.
Solution Approach 2:
The preliminary machining removes most of the material and creates a near-final geometry, so the subsequent thread rolling only needs to perform partial deformation to achieve the final precise profile. This partial action approach reduces the energy and torque requirements of the rolling process while still achieving the desired manufacturing precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method effectively smooths out roughness peaks, reduces material waste, and enhances the mechanical stress resistance of the ball raceway by minimizing torque requirements and optimizing the thread profile geometry, resulting in a higher-quality final thread profile with improved resilience.
Implementation Method 1
The rolling or rolling off of the roller profile along the preliminary thread profile results in plastic deformation on the surface of the preliminary thread profile
Data Source
AI summary
A method for producing a ball raceway on a workpiece includes providing the workpiece, machining a preliminary thread profile on the workpiece and providing a thread rolling tool. The thread rolling tool has a tool shank, and the tool shank has a free end with a tool head having a roller profile. The method also includes clamping the workpiece into the thread rolling tool, rotating the workpiece about an axis of rotation, moving the tool shank longitudinally along the workpiece, and rolling the roller profile on the preliminary thread profile to generate a final thread profile.