Steering Gear Rack Forging With Wider Toothing and Larger Back Radius
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Solution Overview
Problem
Existing methods for producing steering gear racks face limitations in achieving optimized toothing and back geometry, leading to restricted force transmission and increased production complexity, with current die forging techniques requiring complex dies and limited toothing widths.
Innovation Solution
The method involves using a die with a back mold clearance larger than the unmachined radius of the blank, allowing for a larger back radius and correspondingly wider toothing width, reducing production complexity and enabling a more efficient force transmission by using a simpler two-part die construction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a larger back radius is used to reduce local load and improve force transmission, then the toothing width can be increased, but the die construction becomes more complex
Solution Approach 1:
The die is divided into two separate parts: a back die part that forms the back radius and a toothed die part that forms the toothing. This segmentation allows each die part to be optimized independently, enabling a large back radius without requiring a complex integrated die structure. The back die part creates the cylindrical or D-shaped back geometry while the toothed die part creates the toothing profile, resolving the contradiction between large back radius and simple die construction.
2Reliability
If a larger back radius is used to reduce local load, then wear is reduced, but the die construction becomes more complex
Solution Approach 1:
By segmenting the die into separate back die part and toothed die part, the system achieves a large back radius that reduces local load and wear on the rack, while avoiding the need for a complex single integrated die. The segmentation allows the back radius to be optimized for wear reduction independently from the toothing geometry.
3Ease of manufacture
If a larger back radius is used to improve force transmission, then production costs can be reduced through simpler dies, but the toothing width is limited by the die cavity width
Solution Approach 1:
The segmentation of the die allows the back die part to define the back radius and the toothed die part to define the toothing width independently. This enables the toothing width to be maximized within the available die cavity width while maintaining a large back radius, optimizing both force transmission capability and production cost through simpler separated dies rather than a complex integrated die.
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 results in a rack with improved force transmission capabilities, reduced wear, and lower production costs, while maintaining a lower surface pressure on bearing faces, enhancing the sliding behavior and load-bearing capacity of the rack.
Implementation Method 1
The material of the blank, usually steel or other metals that are capable of hot-forming or cold-forming, is plastically deformed herein and flows in the die until the mold clearances of the cavity are completely filled.
Data Source
AI summary
A rack for a steering gear includes a toothed portion with a toothing extending along a longitudinal axis, and a generally cylinder-segment-shaped back opposite the toothing and having a back radius. A method for producing such a rack includes forming a cylindrical blank with an unmachined radius between a toothed die part having a toothed mold clearance and a back die part having a back mold clearance in a die cavity. The die may have a generally cylinder-segment-shape. In an open position of the die, the blank may be inserted between the toothed mold clearance and the back mold clearance. The toothed die part and the back die part in a forging stroke for closing the cavity may then be moved in a closing direction to a closed position. The back radius of the back mold clearance may be larger than the unmachined radius of the blank.