Lever Fastening Mechanism for Drafting Unit Support Rods
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Solution Overview
Problem
Existing fastening devices for support rods in drafting systems either damage the rod due to torque-induced stress or require manual alignment, which is impractical and prone to misalignment.
Innovation Solution
A two-armed lever system that pivots about a parallel axis, allowing the support to be easily positioned and secured without engaging recesses during assembly, directing torque forces directly onto the pivot axis and minimizing damage, with an L-shaped design and screw mechanism for low-torque fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a fastening screw engages directly into a borehole in the support rod, then the support can be fixed in place, but the borehole is damaged by the tightening torque and the fastening screw absorbs operational torque leading to further damage
Solution Approach 1:
The fastening function is segmented into two separate components: a lever arm that engages with the support rod recess (handling positioning and torque transmission) and a separate fastening screw that secures the lever arm (handling only clamping force). This segmentation prevents the screw from being subjected to operational torque, eliminating damage to the support rod borehole.
Solution Approach 2:
The lever arm acts as an intermediary between the support rod and the fastening screw. It transmits the operational torque to the pivot axis while allowing the screw to only perform its fastening function. The lever arm mediates the force transmission path, preventing direct torque application to the screw and support rod interface.
2Ease of operation
If a lever arm is used to fasten the support, then positioning is improved, but the lever arm must be manually held in position during assembly and operational torque can change the set inclination
Solution Approach 1:
The lever arm is pre-designed with a specific geometry where the outer contour of its end face has a radius of curvature matching the distance to the pivot axis. This preliminary geometric configuration ensures that when the lever arm engages the support rod recess, the force from operational torque is automatically directed onto the pivot axis, preventing inclination changes without requiring manual adjustment during operation.
Solution Approach 2:
The end face of the lever arm features a convexly curved outer contour with a specific radius of curvature that corresponds to both the distance from the pivot axis and the axial extension of the lever arm. This curvature ensures proper force direction and engagement geometry, eliminating the need for manual holding during assembly and preventing torque-induced inclination changes.
3Object-affected harmful factors
If the lever arm is designed with a convexly curved end face, then torque forces are directed onto the pivot axis preventing damage, but the design complexity increases
Solution Approach 1:
The lever arm's end face is designed with a specific radius of curvature parameter that matches the distance to the pivot axis. This parameter change from a flat or simple shaped end face to a precisely curved one ensures that the contact geometry automatically directs operational forces onto the pivot axis, preventing damage while maintaining a relatively simple overall lever arm structure.
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 solution prevents damage to the support rod and simplifies the assembly process by ensuring the support is securely fastened without applying torque to the assembly components, maintaining stability during operation.
Implementation Method 1
a two-armed lever (12) which can be pivoted about a pivot axis (14) arranged parallel to the axis of the holding rod (3)
Implementation Method 2
a means (13) for positioning the lever (12) in a transport and assembly position or a fastening position
Data Source
Figure 1~2
Figure 3~4
AI summary
The device has a double-arm lever swivelable around a swiveling axis (14) arranged axial-parallel to a holding rod (3). An L-shaped lever (12) has two lever arms, where one of the lever arms is brought in contact with a recess provided in the rod for fixing of a support (2) of an upper roller-supporting-and loading arm (1). A screw (13) for positioning the lever in a transport and mounting position or a fixing position is engaged at another lever arm. The lever arms are designed such that the arms include an angle between 80 degree and 120 degree between longitude axes.