CNC Thread Angular Orientation via Tool Presetting
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Solution Overview
Problem
Current methods for forming threads in engine cylinder heads for spark plugs lack precision in angular orientation, leading to potential disruptions from fuel sprays and increased scrap rates due to tool flexibility and human error in CNC machining centers.
Innovation Solution
A method using a CNC machining center with a tool holder that measures and sets the thread-forming tool's position accurately, ensuring the thread starts at a predetermined angle by calculating the distance and angle adjustments, allowing precise angular orientation without special operator interaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional thread forming methods are used in CNC machining centers, then productivity is maintained, but manufacturing precision of thread angular orientation deteriorates due to tool flexibility and human error
Solution Approach 1:
The patent applies preliminary action by measuring and recording the thread-forming tool's angular position and axial distance from a reference point on the tool itself before machining. This pre-measured data is then used to automatically position subsequent tools, eliminating the need for complex real-time measurement systems during production while maintaining high precision.
Solution Approach 2:
The patent uses copying by transferring the measured angular position and axial distance data from a reference tool to subsequent thread-forming tools. The presetter creates a digital copy of the positioning parameters that guides the CNC machine in reproducing the exact same angular orientation for each thread, ensuring consistent precision without requiring complex positioning hardware.
2Manufacturing precision
If manual positioning and measurement by operators is used, then device complexity is minimized, but manufacturing precision deteriorates due to human error
Solution Approach 1:
The patent applies self-service by enabling the thread-forming tool to measure and record its own angular position and axial distance from a reference point using the presetter device. The tool's inherent features (datum face, thread location) are used as the measurement reference, eliminating the need for external complex measurement systems or manual operator intervention.
Solution Approach 2:
The patent replaces manual mechanical measurement and positioning with an automated digital measurement and data transfer system. The presetter automatically measures the tool's geometry and angular position, stores the data digitally, and transmits it to the CNC machine, replacing operator skill-based positioning with automated digital control.
3Manufacturing precision
If thread forming is performed in deep recesses with flexible tools, then adaptability to various workpiece geometries is improved, but manufacturing precision deteriorates due to tool flexibility
Solution Approach 1:
The patent applies preliminary action by pre-measuring and recording the exact angular position and axial distance of the thread-forming tool before it is used to machine deep recesses. This pre-captured positioning data compensates for tool flexibility during the actual machining operation, ensuring that even flexible tools used in deep recesses maintain precise thread concentricity and angular orientation.
Data Source
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AI summary
A method of producing a rotationally orientated thread starting at a desired angular position and suitable for mass production is provided. The method is particularly suitable for improving the angular positioning of spark plugs in car engines. The method involves measuring precisely the length of the tool and the distance, at a particular angular position, of a full thread form of the thread to the tip, so that its start position at the tip can be calculated. Using that distance as an offset of the length of the tool reported to the CNC machine, and starting from its reference position, it commences producing the thread in the bore at the desired angular position of the bore.