Bushing Assembly Height Checking Fixture Design
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Solution Overview
Problem
Conventional measuring tools are inadequate for accurately determining the dimensional requirements of assembled bushings, which are critical for evaluating the quality of automobile chassis assembly, particularly in reducing noise and vibration.
Innovation Solution
A checking fixture comprising a jacket, a measuring cylinder, a positioning cylinder, and set screws, with precise fit clearances and geometric features, allows for the measurement of the height difference between a bushing and a steering knuckle, ensuring accurate positioning and detection of assembly quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional measuring tools such as calipers are used to measure the dimension of assembled bushing, then the measurement process is simple, but the measurement precision is insufficient and the dimensional requirements cannot be accurately determined
Solution Approach 1:
The checking fixture is divided into multiple functional components: a jacket with step-shaped top surface for positioning, a measuring cylinder with precise fit clearance (0.005mm) for height measurement, set screws for securing, and a conical positioning cylinder for radial alignment. Each component performs a specific function, collectively achieving high measurement precision while maintaining operational simplicity
Solution Approach 2:
The measuring cylinder acts as an intermediary element between the jacket and the bushing assembly. With its precisely controlled fit clearance of 0.005mm, it mediates the measurement process by providing a reference surface that directly contacts the bushing end face, enabling accurate height dimension determination without requiring complex measurement instruments
2Productivity
If conventional measuring tools are used, then the device structure is simple, but the measurement speed is slow and the detection efficiency is low
Solution Approach 1:
The checking fixture is pre-configured with precise geometric relationships during manufacturing: the step-shaped jacket provides predetermined positioning surfaces, the measuring cylinder has pre-established fit clearances (0.005mm with jacket, 0.01mm with positioning cylinder), and the conical end is pre-formed for radial positioning. This preliminary precision ensures that during actual measurement, high detection efficiency is achieved without sacrificing measurement precision
Solution Approach 2:
The measuring cylinder is nested within the jacket, and the positioning cylinder is nested within the measuring cylinder, creating a hierarchical structure. This nesting arrangement consolidates multiple measurement and positioning functions into a compact integrated fixture, enabling quick setup and high-speed detection while maintaining the precision required for strict dimensional requirements
3Measurement precision
If a precise checking fixture is designed, then the measurement precision is high, but the manufacturing cost increases
Solution Approach 1:
High precision requirements are applied only to critical surfaces: the outer cylindrical surface of the measuring cylinder has a fit clearance of 0.005mm with the jacket, and the positioning cylinder has 0.01mm clearance. Other surfaces use standard tolerances. This localized precision approach ensures measurement accuracy where needed while reducing manufacturing costs on non-critical surfaces
Solution Approach 2:
The fixture incorporates adjustable set screws that can be tightened to secure the measuring cylinder in position. This dynamic adjustment capability allows for easy assembly and disassembly, facilitating maintenance and replacement without requiring complex manufacturing processes, thereby balancing precision requirements with manufacturing ease
Data Source
AI summary
Disclosed is a bushing assembly height checking fixture, which is composed of a jacket, set screws, a measuring cylinder and a positioning cylinder. When the bushing assembly height checking fixture is used, the lower cone of the positioning cylinder is fitted with the orifice edge of an inner shaft hole of a bushing, and the checking fixture is positioned radially; the bottom surface of the jacket is flush with the assembly positioning end face of a workpiece, and the checking fixture is positioned axially; then the bottom surface of the measuring cylinder is flush with the end face of the bushing, the position of the top surface of the measuring cylinder is observed, and if the top surface of the measuring cylinder is in the middle of the top step of the jacket, it shows that the height after the workpiece is assembled is qualified.