Bent Thermoplastic Pipe Precision Bending
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Solution Overview
Problem
Existing methods for producing bent pipes from thermoplastic materials face challenges in achieving high production precision, including thermal distortion and limited precision due to ovality, which affects installation and longevity, especially in applications requiring stress-free connections and weight-saving constructions.
Innovation Solution
A method involving heating a straight pipe element beyond its glass transition temperature using a controlled bending tool, followed by precise bending and cooling to maintain temperature distribution, ensuring positional tolerances of ±1 mm and minimal ovality, utilizing temperature-controlled heating and cooling methods with feedback control to achieve precise bending angles and radii.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a thermoplastic pipe is bent in a heated state around a bending body using infrared emitter, then the pipe can be formed into desired shape, but high thermal distortion and limited production precision occur
Solution Approach 1:
The pipe bending process is divided into multiple heating zones along the pipe length, with each zone independently controlled to achieve precise temperature distribution. This segmentation allows different portions of the pipe to be heated to different temperatures, enabling accurate control of the bending shape while minimizing thermal distortion in non-bending areas.
Solution Approach 2:
Heating is applied locally only to the specific regions of the pipe that require bending, rather than heating the entire pipe uniformly. The heating装置 is positioned to target only the bending section, maintaining precise temperature control where needed while keeping other areas at ambient temperature, thus reducing overall thermal distortion.
2Ease of manufacture
If heating temperature is increased to improve formability, then the pipe can be bent more easily, but thermal distortion increases
Solution Approach 1:
The process utilizes controlled changes in temperature parameters, heating the pipe to a specific temperature range that provides optimal formability without excessive thermal distortion. The heating is maintained only long enough to achieve the desired shape, then quickly cooled to freeze the formed geometry, thus balancing ease of manufacture with minimal thermal distortion.
Solution Approach 2:
The heating process is applied periodically and temporarily only to the bending zone, heating the pipe sufficient to achieve formability, then rapidly cooling it to lock in the shape. This periodic heating and cooling cycle allows easy forming while limiting the duration of high temperature exposure, thereby reducing thermal distortion.
3Manufacturing precision
If ovality is reduced to improve connection quality, then installation becomes easier, but production complexity increases
Solution Approach 1:
The pipe is pre-heated and held in a positioning fixture before bending begins, ensuring that the pipe is properly aligned and supported from the start. This preliminary positioning prevents ovality development during the bending process, achieving high connection quality without requiring complex post-bending correction devices or procedures.
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 method produces bent pipes with high precision, minimizing thermal distortion, maintaining roundness, and ensuring stress-free installation, while reducing ovality and frictional resistance, thus enhancing the longevity and performance of thermoplastic pipes in applications like aircraft construction.
Implementation Method 1
a portion of the straight pipe element that is located in the bending region of the tool is heated by the bending region being heated
Implementation Method 2
heated to a temperature which exceeds the glass transition temperature of the thermoplastic material
Implementation Method 3
the bent pipe element is cooled to a temperature which lies below the glass transition temperature
Implementation Method 4
During the cooling, all regions of the bent pipe element reach a temperature below the glass transition temperature
Data Source
AI summary
A method for producing a bent pipe from thermoplastic material with end cross-sections, central points of which have in relation to one another a positional tolerance on the basis of LN xy/JAR xy/FAR xy in relation to one another. A straight pipe element is introduced into a tool and a portion of the straight pipe element is heated that is located in the bending region to a temperature which lies above a glass transition temperature of the thermoplastic material by a first temperature value. The straight pipe element is bent about the heated bending region of the tool by a freely selectable bending angle, which has a spatial alignment in an XYZ system of coordinates that is fixed with respect to the pipe. The pipe is then cooled below the glass transition temperature by a second temperature value.