Screw Shaft Rolling Structure to Prevent End Walking Errors
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Solution Overview
Problem
The rolling process for forming male-side screw portions in feed screw mechanisms often results in reduced machining precision due to walking of the workpiece, leading to a shortened operating stroke and functional issues with the screw portions.
Innovation Solution
A screw shaft design with a large-diameter shaft portion and adjacent small-diameter shaft portions, each with a helical rolling mark in phase with the spiral curve of the male-side screw portion, is used to maintain machining precision and extend the operating stroke by stabilizing the rolling process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If walking is allowed to occur during the rolling process to form the male-side screw portion, then the rolling process can complete the entire axial length, but the machining precision at the end portions deteriorates
Solution Approach 1:
The patent applies preliminary action by forming a small-diameter shaft portion at the end of the workpiece before the rolling process. This pre-formed portion serves as a guide and support surface that prevents workpiece displacement during rolling, thereby maintaining machining precision at the end portions while allowing the rolling process to complete the entire axial length.
Solution Approach 2:
The small-diameter shaft portion acts as an intermediary element between the workpiece and the rolling dies. It provides a stable reference surface that mediates the interaction during the rolling process, preventing direct contact between the rolling dies and the end portion of the workpiece, thus eliminating displacement and maintaining precision.
2Ease of manufacture
If the workpiece moves in the axial direction during rolling, then the rolling process can proceed, but the operating stroke of the feed screw mechanism is shortened
Solution Approach 1:
The small-diameter shaft portion is formed in advance at the end of the workpiece to serve as a guide surface. This preliminary structure enables the rolling process to proceed without excessive workpiece movement, thereby maintaining the operating stroke length of the feed screw mechanism while ensuring manufacturing feasibility.
3Adaptability or versatility
If the rolling load distribution changes significantly during the rolling process, then the rolling process adapts to the workpiece, but the relative displacement between rolling dies and workpiece increases
Solution Approach 1:
The small-diameter shaft portion serves as a stable intermediary that maintains consistent rolling load distribution. By providing a guide surface that the rolling dies can follow, it prevents sudden changes in load distribution that would cause relative displacement, thereby maintaining manufacturing precision while allowing process adaptation.
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
The proposed design ensures good machining precision on both ends of the screw shaft, maintaining a sufficient operating stroke and enhancing the adjustment range of the feed screw mechanism.
Implementation Method 1
the work is rolled between a plurality of rolling dies, and the outer circumferential surface of the work is plastically deformed by these rolling dies to form the male-side screw portion
Data Source
AI summary
A screw shaft includes a large-diameter shaft portion having a male-side screw portion over the entire length of the outer circumferential surface thereof; a first small-diameter shaft portion arranged adjacent to one side in the axial direction of the large-diameter shaft portion, and having an outer diameter that is smaller than the outer diameter of the large-diameter shaft portion, and having a helical first rolling mark on the outer circumferential surface thereof; and a second small-diameter shaft portion arranged adjacent to the other side in the axial direction of the large-diameter shaft portion, and having an outer diameter that is smaller than the outer diameter of the large-diameter shaft portion, and having a helical first rolling mark on the outer circumferential surface thereof.