Fatigue Testing Apparatus for WH-Type Skeleton Bulge Tools
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Solution Overview
Problem
The existing technologies face challenges in accurately measuring the fatigue level of bulge tools, particularly in the WH-type skeleton, due to stress concentration and fatigue failure risks at the boundary areas, and difficulties in machining and heat treatment for high hardness while preventing stress concentration and fatigue failure.
Innovation Solution
An apparatus for fatigue testing a bulge tool with a WH-type skeleton, comprising a fixing bracket, tool housing, moving rail, pusher, measurement means, and drive means, which applies repetitive loads to the boundary area between the bulge portion and slots, allowing for accurate measurement of fatigue failure by counting the number of load applications until failure occurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the boundary area between the bulge portion and slots is repeatedly subjected to stress during the bulge process, then the pipe jointing is accomplished through local plastic deformation, but stress concentration and fatigue failure occur at the boundary area
Solution Approach 1:
The patent applies preliminary action by conducting fatigue tests on bulge tool prototypes before actual manufacturing. The testing apparatus simulates repeated bulge operations to identify and address potential fatigue failure points in advance, allowing design modifications to prevent stress concentration issues before they occur in production tools
Solution Approach 2:
The patent employs parameter changes by systematically varying test parameters including load magnitude, cycle frequency, and boundary area geometry in fatigue testing. This enables optimization of the bulge tool design to minimize stress concentration while maintaining the necessary plastic deformation capability for pipe jointing
2Strength
If the bulge tool is designed to achieve high hardness through heat treatment, then the tool strength is improved, but machining difficulty increases and stress concentration risks rise
Solution Approach 1:
The patent applies preliminary action by performing fatigue testing on heat-treated bulge tool prototypes to evaluate the impact of heat treatment parameters on both strength and stress concentration. This allows optimization of heat treatment processes to achieve the necessary hardness while maintaining manufacturability and reducing fatigue risks
Solution Approach 2:
The patent employs local quality by applying heat treatment selectively to specific regions of the bulge tool that require high hardness, while leaving other areas in a more machinable state. This localized approach ensures tool strength where needed while maintaining ease of manufacture and reducing stress concentration in critical boundary areas
3Adaptability or versatility
If the slots of the bulge tool are opened to expand the tool for pipe jointing, then the bulge portion is formed to accomplish fastening, but the boundary area experiences high stress and fatigue loading
Solution Approach 1:
The patent applies preliminary action by conducting fatigue tests that simulate the repeated opening and expanding operations of the bulge tool. This preliminary testing identifies design weaknesses in the boundary area between slots and bulge portions, allowing modifications to improve fatigue life before the tool is deployed for actual pipe jointing operations
Solution Approach 2:
The patent employs parameter changes by optimizing geometric parameters such as slot configuration, bulge portion radius, and boundary area thickness to reduce stress concentration. The testing apparatus enables systematic variation of these parameters to find the optimal balance between expansion capability and fatigue resistance
Data Source
AI summary
Provided is an apparatus for fatigue testing a bulge tool having a WH-type skeleton, the apparatus including: a fixing bracket having tool holes penetrated through opposite sides thereof; a tool housing coupled to the tool hole of the fixing bracket and having the bulge tool inserted and installed therein; a moving rail installed at one side of the fixing bracket in a lengthwise direction of the tool housing and providing a reciprocating movement path facing the tool housing; a moving bracket reciprocating along the moving rail; a pusher protrudingly installed from the moving bracket toward the tool housing and moving in and out of the bulge tool; a measurement means installed between the pusher and the moving bracket, measuring a load applied to the bulge tool; and a drive means for generating power reciprocating the moving bracket on the moving rail.