Motor Vehicle Support Tube Notch Formation and Tear Prevention
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Solution Overview
Problem
The existing manufacturing methods for motor-vehicle support tubes often result in tears and material waste, leading to reduced quality and increased costs due to the need for additional machining and potential corrosion at notch areas.
Innovation Solution
The support tube design incorporates lateral indents adjacent to the latch face, which redirects excess material into side areas, and an embossing die with a mandrel structure that creates a counter-pressure to prevent tears, allowing for deeper recesses without material loss or surface defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the notch depth is increased to reduce weight and eliminate machining, then material displacement becomes excessive, causing tears in the tube wall
Solution Approach 1:
The patent introduces a preliminary rounding step that rounds the inner corner of the notch before the embossing process. This preliminary action prepares the material flow path, preventing tears during subsequent embossing by eliminating sharp corners that would cause stress concentration and material rupture.
Solution Approach 2:
The patent changes the geometric parameters of the notch, specifically rounding the inner corner radius and optimizing the notch depth-to-wall-thickness ratio. These parameter changes allow deeper notches that displace material into the tube interior without causing tears, thereby eliminating the need for post-machining while maintaining structural integrity.
2Weight of moving object
If the notch is formed deeper into the tube wall to reduce material usage, then tears occur in the corner between notch bottom and latch face
Solution Approach 1:
The rounding of the inner corner is performed as a preliminary action before embossing, creating a stress-free zone that prevents tear propagation even when notches are deep. This allows maximum material displacement into the tube interior for weight reduction while maintaining reliability.
Solution Approach 2:
The patent applies local quality by rounding only the specific inner corner area where tears typically occur, while maintaining the sharpness and precision of other notch surfaces. This localized modification prevents tears without compromising the overall notch functionality or requiring additional material.
3Productivity
If traditional embossing is used to form notches, then tears form reducing quality and requiring rejection or rework
Solution Approach 1:
The preliminary rounding step is integrated into the embossing tooling itself, combining two operations (rounding and embossing) into a single tool pass. This maintains high productivity while eliminating tears, as the rounded corner geometry is created simultaneously with the notch formation without requiring separate operations or causing material rupture.
Solution Approach 2:
The embossing tool parameters are optimized with a rounded die corner radius that matches the desired final notch corner radius. This parameter change in the tooling geometry enables tear-free embossing while maintaining production speed, as the rounded contact area distributes stress more evenly during material displacement.
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 design reduces notch sensitivity and tear formation, enhancing the stability and uniformity of the support tube while eliminating waste and potential corrosion, resulting in a more reliable and cost-effective manufacturing process.
Implementation Method 1
The material, being displaced during the formation of the notch in a solid rod would project beyond the outer contour of the support rod and must therefore be removed utilizing an additional manufacturing step, for example, by machining. In a support tube the material may be displaced into the interior of the tube such that no subsequent machining is necessary.
Data Source
AI summary
A support tube adapted to carry a motor-vehicle accessory and to slide in a bearing tube provided with a latch element is hollow, cylindrical, centered on an axis, and formed with a plurality of outwardly open notches. These notches are each in turned formed by a flat latch face extending generally perpendicular to the axis, an outwardly open indent adjacent the latch face, a cam face extending from the latch radially outward to an outer surface of the tube, and a flat base face extending generally parallel to the axis from an inner edge of the latch face to an inner edge of the cam face.