Seamless Pipe Manufacturing via Mandrel Forging and Push Drawing

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing methods for manufacturing large diameter seamless steel pipes face challenges in achieving high dimensional accuracy, particularly in wall thickness, leading to low yield due to poor forming precision in mandrel forging processes.

Innovation Solution

Combining mandrel forging and push bench pipe-making processes by subjecting seamless steel pipes to diameter reduction at one end to create a closed end, allowing for high dimensional accuracy through push-drawing with a mandrel and die assembly, thereby enhancing wall thickness precision.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If mandrel forging pipe-making process is used, then a wide range of pipe sizes can be achieved, but dimensional accuracy deteriorates

Engineering Contradiction:

Improverange of pipe sizesVSAvoiddimensional accuracy

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The pipe-making process is divided into two distinct stages: first, mandrel forging to create a primary hollow shell with a closed end, and second, push bench processing to achieve final dimensional accuracy. This segmentation allows each process to optimize for its specific function - mandrel forging for versatility in size and push bench for precision.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The mandrel forging process performs preliminary forming to create a primary hollow shell with a closed end, preparing the workpiece for the subsequent push bench process. This preliminary action enables the second process to focus on achieving high dimensional accuracy without needing to create the closed end structure.

Inventive Principle:

Principle #10Preliminary action

2Adaptability or versatility

If mandrel forging pipe-making process is used, then thick-walled large diameter pipes can be manufactured, but wall thickness accuracy deteriorates

Engineering Contradiction:

Improvethick-walled large diameter capabilityVSAvoidwall thickness accuracy

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The process segments wall thickness control into two phases: mandrel forging establishes the initial thick-walled structure and closed end, while push bench processing precisely controls the final wall thickness. This allows thick-walled large diameter pipes to be manufactured with high wall thickness accuracy.

Inventive Principle:

Principle #1Segmentation

3Adaptability or versatility

If mandrel forging pipe-making process is used, then production flexibility is improved, but machining removal amount increases

Engineering Contradiction:

Improveproduction flexibilityVSAvoidmachining removal amount

Core Design Contradiction:

Adaptability or versatilityVSLoss of substance

Solution Approach 1:

The push bench process performs preliminary sizing to achieve final dimensional accuracy before finishing operations. This preliminary action on the primary hollow shell ensures that subsequent machining requires minimal removal, reducing material loss while maintaining production flexibility.

Inventive Principle:

Principle #10Preliminary action

4Adaptability or versatility

If mandrel forging pipe-making process is used, then process versatility is improved, but yield deteriorates

Engineering Contradiction:

Improveprocess versatilityVSAvoidyield

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The segmented two-process approach allows mandrel forging to handle diverse pipe size requirements while push bench processing ensures high dimensional accuracy. This combination maintains process versatility for different pipe specifications while improving yield by minimizing machining removal and maximizing usable product.

Inventive Principle:

Principle #1Segmentation

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 enables the production of seamless steel pipes with a wide range of sizes and high wall thickness accuracy, significantly reducing the amount of machining required in the finish process and improving yield by achieving dimensional accuracy within 10 mm of the desired size.

Implementation Method 1

push-drawing the workpiece through a die assembly to reduce the wall thickness thereof

Methodology Applied

Scientific EffectPlastic deformation: Plasticity

Implementation Method 2

hot working the hollow billet by open-die forging

Methodology Applied

Scientific EffectThermal heating: Heating

Data Source

PatentEP2786814B1Method for manufacturing seamless pipe

Publication Date: 2017.08.02 NIPPON STEEL & SUMITOMO METAL CORP

Figure 1~3
Figure 4

AI summary

A method of manufacturing a seamless steel pipe including the steps of: providing a hollow billet with a mandrel inserted therein and forging the hollow billet into a primary hollow shell of a predetermined diameter and thickness; subjecting the primary hollow shell to diameter reduction at one end portion thereof; and providing the primary hollow shell with a mandrel inserted therein, the primary hollow shell having the diameter reduced portion at the one end portion thereof, and subjecting the primary hollow shell to push-drawing using a push bench. With this method, it is possible to manufacture seamless steel pipes of a wide range of manufacturable sizes (large diameter or thick-walled pipes) with high dimensional accuracy, particularly with high wall thickness accuracy.