Thread Forming Tool with Drilling Section for Pilot Hole Threading
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Solution Overview
Problem
Conventional methods for producing internal threads in workpiece pilot holes often result in material weakenings and defects on the thread crest, which impair the setting behavior of screw members due to plastic deformation and chip damage during the cutting process.
Innovation Solution
A thread shaping tool with a drilling section and a thread shaping section, where the drilling section is used to expand the thread inner diameter to the final minor diameter, and includes features like chip grooves and a coolant system to manage chip removal and reduce material defects, ensuring a stress-free operation and complete removal of defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If non-cutting thread shaping is used to produce internal threads, then the thread forming speed is improved, but material weakenings and defects form on the thread crest impairing screw member setting behavior
Solution Approach 1:
The thread shaping process is segmented into multiple passes: a first thread shaping pass that forms the initial thread profile, and a second thread shaping pass that refines the thread crest. This segmentation allows the material to be gradually formed without excessive plastic deformation in a single pass, reducing defects while maintaining productivity benefits of non-cutting shaping.
Solution Approach 2:
The first thread shaping pass performs a preliminary action by forming an initial thread profile with a larger thread inner diameter. This preliminary thread profile prepares the workpiece for the second pass, allowing the final thread crest to be formed with controlled plastic deformation and reduced material weakenings.
2Reliability
If thread inner diameter is expanded by machining to remove defects, then screw member setting behavior is improved, but chips produced during cutting can damage the internal thread
Solution Approach 1:
Instead of using traditional cutting machining that produces chips, the invention extracts the harmful cutting process and replaces it with non-cutting thread shaping. The second thread shaping pass removes material weakenings through controlled plastic deformation without generating chips that could damage the internal thread.
Solution Approach 2:
The invention substitutes the mechanical cutting system with a non-cutting thread shaping system. Instead of using cutting tools that remove material through chip formation, the second thread shaping pass uses controlled plastic deformation to refine the thread profile and eliminate defects without producing chips.
3Strength
If pilot hole diameter is reduced to maintain sufficient thread profile height, then thread strength is improved, but the drilling section must be longer increasing tool complexity
Solution Approach 1:
The tool is designed with dynamic characteristics where the drilling section and thread shaping section are integrated in a flexible manner. The tool can accommodate varying pilot hole diameters and depths by adjusting the engagement of the thread shaping section, allowing optimization of thread profile height without requiring excessive tool length for all applications.
Solution Approach 2:
The drilling section and thread shaping section are merged into a single integrated tool. This combination allows the tool to perform both functions sequentially in one operation, eliminating the need for separate drilling and thread shaping tools, and reducing overall tool complexity despite the extended functionality required.
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 ensures a durable and reliable screwed connection by removing material defects and optimizing chip removal, reducing the pilot hole diameter, and maintaining sufficient thread profile height for effective screw engagement.
Implementation Method 1
includes features like chip grooves and a coolant system to manage chip removal and reduce material defects
Implementation Method 2
In the process of non-cutting thread shaping, the workpiece material is plastically deformed on the pilot hole wall, thereby forming an internal thread
Implementation Method 3
at least one chip groove is associated with the drilling section of the tool, by means of which the chips produced when the thread inner diameter is expanded to the thread minor diameter can be transported away
Data Source
AI summary
A tool for producing an internal thread in a workpiece pilot hole having a thread major diameter and a thread minor diameter, which tool has a thread-forming section, by which an internal thread profile can be produced in a pilot hole wall. The internal thread profile having the thread major diameter and a thread inner diameter. The tool has a drilling section, by which the thread inner diameter of the internal thread profile can be expanded to the thread minor diameter by machining. At least one, in particular exactly one chip groove is associated with the drilling section of the tool, by which chip groove the chips produced as the thread inner diameter is expanded to the thread minor diameter can be transported away.