Tapered Pipe Forming With Pre-Bent Boundary to Prevent Cracking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
UO forming methods often result in wrinkling or cracking near the boundary between the pipe body and the tapered part due to the radial inward tilt of the tapered part, which is exacerbated by the extension of the tapered part along the longitudinal direction of the pipe.
Innovation Solution
A method that involves press-forming a plate member into a U shape and then into an O shape, where the boundary between the pipe body and tapered part is pre-bent inward from the inner surface to reduce stress concentrations and prevent wrinkling or cracking, using a punch with a ridge to form a groove-shaped bend that work-hardens the area and maintains the taper angle during subsequent forming processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the tapered part is bent and tilted radially inward after UO forming, then the pipe structure is achieved, but wrinkling or cracking occurs near the boundary between the pipe body and the tapered part
Solution Approach 1:
The patent applies preliminary action by bending the plate member corresponding to the tapered part toward the inner peripheral surface before UO forming is performed. This pre-bending creates a groove-shaped bend at the boundary that prevents wrinkling and cracking during subsequent forming operations, thereby achieving the tapered part tilt while maintaining boundary integrity.
2Reliability
If the boundary is pressed to form a bend, then wrinkling and cracking are reduced, but the plate member may become excessively thin at the bend
Solution Approach 1:
The patent applies local quality by creating a groove-shaped bend with a curved section rather than a sharp angle. This curved geometry distributes the deformation more evenly, preventing excessive thinning at the bend location while still achieving the work hardening effect needed to prevent wrinkling and cracking.
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
This method effectively reduces wrinkling and cracking at the boundary between the pipe body and tapered part, maintains the taper angle, and minimizes springback and thermal deformation, ensuring a stable and accurate pipe shape.
Implementation Method 1
since the portion where the bend has been formed is work-hardened by compression
Data Source
AI summary
A method for manufacturing a pipe includes: press-forming a plate member into a U shape; and press-forming the plate member formed into the U shape into an O shape. The pipe includes a pipe body and a tapered part tilted radially inward and protruding from one end of the pipe body. Before the plate member is press-formed into the U shape, a boundary between a portion of the plate member corresponding to the pipe body and a portion of the plate member corresponding to the tapered part is pressed from a surface of the plate member corresponding to an inner peripheral surface of the pipe to bend the portion of the plate member corresponding to the tapered part toward the surface of the plate member corresponding to the inner peripheral surface of the pipe.