Checking Fixture
A checking fixture, also known as a testing device, is a tool used to detect, measure, and adjust various indicators. The performance of this tool is to accurately and repeatable check its key features. It is widely used in the automotive industry, such as in processes such as vehicle production and maintenance.
Automobile Checking Fixtures ｜ Automobile Inspection Tools
Automobile checking fixtures, also known as automobile inspection equipment, are tools used to detect, measure, and adjust various indicators of automobiles. There are more than one types of automotive checking fixture, including various measuring tools, instruments, and equipment, which play an important role in vehicle production, maintenance, and other processes, ensuring the safety and reliability of vehicle operation.
Types of Automotive Checking Fixtures
- Measurement Checking Fixtures: such as calipers, gauges, rulers, etc., are used to measure the dimensions and spacing of various parts of the car.
- Fault Diagnosis Checking Fixtures: such as scanners, diagnostic equipment, etc., are used to detect car fault codes and conduct fault diagnosis.
- Power Performance Testing Instruments: such as engine tachometer, oil pressure gauge, thermometer, etc., are used to test the power performance parameters of automobiles.
- Testing Instruments: such as exhaust analyzers, chassis measuring instruments, car light detectors, etc., used to detect car exhaust emissions, chassis height, car light brightness, etc.
- Calibration Checking Fixtures: such as voltage regulators, calibration blocks, weighing devices, etc., are used to calibrate and adjust gauges.
- Other Auxiliary Checking Fixtures:such as probes, suction cups, cleaning agents, etc., are used to assist in car maintenance and testing.
The Application of Automotive Checking Fixtures
Automotive checking fixtures have several key applications in ensuring quality control and verifying the dimensional accuracy of various automotive components and assemblies. Here are some of the main applications of automotive checking fixtures:
- Inspection of Plastic Parts
Checking fixtures are widely used to inspect plastic parts used in automotive interiors and exteriors. These include fixtures for verifying dimensions, geometry, and surface finish of plastic components like dashboards, door trims, bumper parts, etc. The fixtures allow accurate positioning and clamping of the plastic part for inspection using gauges, probes, or coordinate measuring machines (CMMs).
- Inspection of Sheet Metal Stampings
A major application is inspecting sheet metal stamped parts like body panels, brackets, reinforcements, etc. The checking fixtures provide precise locating and clamping setups along with checking elements like pins, surfaces, and go/no-go gauges to verify critical dimensions, hole locations, trim lines, flatness, and other geometric dimensioning and tolerancing (GD&T) requirements.
- Inspection of Welded Assemblies
Checking fixtures are employed to inspect welded assemblies of sheet metal parts like body-in-white, subassemblies, etc. The fixtures allow checking part alignment, weld quality, and dimensional integrity after the welding process.
- Inspection of Hot-formed Parts
Specialized checking fixtures are used to inspect parts produced by hot-forming processes like hot stamping. These fixtures can handle the high temperatures involved.
- Inspection During Assembly Processes
Checking fixtures are integrated into automotive assembly lines to verify proper fits, clearances, and alignments of mating parts/subassemblies before final assembly.
- Inspection of Exterior Parts
Dedicated checking fixtures are used to comprehensively inspect the dimensional accuracy of exterior parts like bumpers, grilles, and lighting assemblies against design specifications.
- CMM Inspection Setups
Many checking fixtures are designed to accurately locate and hold parts/assemblies for coordinate measurement on CMMs to capture detailed dimensional data.
General Steps for Designing Checking Fixtures
- Workpiece and Checking Specific Design Modeling
Firstly, it is necessary to refer to the part drawings to analyze the workpiece, preliminarily draft the design plan of the inspection tool, determine the reference plane and concavity and convexity of the inspection tool, detect the cross-section, positioning surface, etc., and briefly draw its two-dimensional schematic diagram
- Design and Modeling of Section Templates
The detection of a key surface of a workpiece generally needs to be achieved through a section template. The section templates of the inspection fixture are divided into two types: rotation type and insertion type. When the span of the section template exceeds 300mm, to ensure the detection accuracy in the vertical direction, it is usually designed as an insertion type, and specific surface detection is performed on the inner surface of the workpiece, while the section template spans the outer surface of the workpiece to detect the outer surface of the key section. Generally, its working surface is 2-3mm away from the outer surface of the workpiece, and its modeling method is similar to that of the inspection fixture surface. The material of the section template is generally steel or aluminum, and the working surface can be made of aluminum or resin. The section template of a complex curved surface may interfere when rotating or inserting, and it can be processed in sections during the actual design.
- Positioning and Clamping of Workpieces
The correct and reasonable positioning of the workpiece is the foundation of accurate measurement. The positioning method of the vehicle body cover on the inspection tool is mainly achieved by clamping the positioning hole and clamp, or by using a permanent magnet to clamp and cooperate. With the widespread application of checking fixtures in car body manufacturing, lever-type movable chucks and permanent magnets are available in a series of products for purchase. The movable chucks are also equipped with different types and sizes of brackets or brackets. Most car body coverings have two locating holes, primary and secondary.
- Design of Bottom Plate Assembly
Stretch the upper surface of the inspection along the reference plane direction for a certain distance, so that its lowest point is greater than a thickness of 150mm, to ensure that the inspection has sufficient strength. At the same time, try to make the inspection-specific bottom surface, that is, the upper surface (base surface) of the bottom plate assembly, in the integer position of the vehicle coordinate system.
- Hole Detection
In body stampings, many important holes and flanges need to be carefully inspected individually.
Importance of automobile checking fixtures
Automobile checking fixtures are not only fundamental tools to ensure the safety and reliability of automobiles but also an important guarantee for improving automobile production efficiency and maintenance quality. Reasonable selection and use of automobile checking fixtures in the entire production, repair, and maintenance of automobiles can improve the overall work efficiency and level of the automobile industry and promote the healthy development of the automobile industry.
Automobile checking fixtures are an indispensable and important tool in the automobile industry, playing a vital role in various links such as automobile production, maintenance, and repair. There are many types of automobile checking fixtures. As practitioners in the automobile industry, they should study the relevant knowledge of automobile checking fixtures more carefully, so that they can use the most suitable automobile checking fixtures in various links such as automobile production, repair, and maintenance.
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