Rack Bar Rolling Sequence for Accurate Ball Screw Grooves
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Solution Overview
Problem
The existing method for manufacturing steering shafts experiences degraded processing accuracy of ball screw grooves due to oscillation of the workpiece at the start of rolling, which affects the precision of the groove formation.
Innovation Solution
A method involving a rolling die abutment step where the die is brought into contact with the intermediate portion of the workpiece, followed by a ball screw groove forming step where the workpiece is moved relative to the die to form the groove from the intermediate portion towards the first end portion, ensuring a wider range of contact and reducing oscillation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the rolling die is brought into abutment against the end portion of the workpiece, then the ball screw groove can be formed, but the workpiece oscillates at the start of rolling degrading processing accuracy
Solution Approach 1:
The rolling die is brought into abutment against the intermediate portion of the workpiece before the actual groove forming begins. This preliminary positioning at the intermediate portion provides initial stability to the workpiece, preventing oscillation at the start of rolling while the groove is subsequently formed as the die moves toward the end portion.
2Stability of the object's composition
If the rolling die contacts the intermediate portion of the workpiece, then workpiece stability is improved, but the groove formation process requires movement from intermediate portion to end portion
Solution Approach 1:
The rolling die is designed to move dynamically during the groove forming process. After initial contact at the intermediate portion for stability, the die progressively moves toward the end portion of the workpiece as the groove is formed, creating a dynamic rather than static contact process that achieves both stability and groove formation.
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 approach significantly improves the processing accuracy of the ball screw groove by stabilizing the workpiece and reducing random walk variations, resulting in improved precision and reduced oscillation during the rolling process.
Implementation Method 1
forming a ball screw groove in the workpiece by moving the workpiece relative to the rolling die
Data Source
AI summary
A method of manufacturing a rack bar includes: a rolling die abutment step of bringing a pair of rolling dies into abutment against an intermediate portion of a workpiece; and a ball screw groove forming step of forming a ball screw groove in the workpiece by moving the workpiece relative to the pair of rolling dies so that a region of the workpiece against which the pair of rolling dies is brought into abutment is moved from the intermediate portion toward a first end portion of the workpiece.