Mandrel Conveying Device for Tube Rolling Mill

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Solution Overview

Problem

Existing tube rolling mills with retained or semi-floating mandrel types face challenges such as low productivity, dimensional inaccuracies, non-uniform temperature distribution, and risk of mandrel damage due to high speeds and premature wear of components like chains, making it difficult to produce small and medium-sized tubes efficiently and flexibly.

Innovation Solution

A mandrel conveying device with a rack and hooking/releasing system that allows controlled speed operation and centering with respect to the mandrel traction axis, eliminating the need for an extractor mill and enabling reverse mandrel insertion, which reduces cycle time and improves tube quality by maintaining uniform temperature and reducing wall thickness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a retained mandrel rolling mill with rack and pinion retaining device is used, then the mandrel can be controlled at constant speed during rolling, but the cycle time increases and productivity decreases to 2 tubes per minute

Engineering Contradiction:

Improvemandrel speed stabilityVSAvoidtube production rate

Core Design Contradiction:

Stability of the object's compositionVSProductivity

Solution Approach 1:

The patent inverts the traditional mandrel retention approach by using a release mechanism instead of a retention mechanism. The mandrel is retained by default during rolling and is released only after the tube has passed through the rolling stands. This inversion allows the mandrel to maintain constant speed during rolling (improving stability) while reducing cycle time (improving productivity) since the release operation is faster and simpler than continuous retention control.

Inventive Principle:

Principle #13The other way round (Inversion)

2Productivity

If a floating mandrel rolling mill is used to achieve high productivity of 4-5 tubes per minute, then cycle time is reduced, but the mandrel acceleration causes compression states in the tube that deteriorate dimensional quality and cause faultiness

Engineering Contradiction:

Improvetube production rateVSAvoidtube dimensional quality

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent inverts the traditional approach by retaining the mandrel at constant speed during rolling rather than allowing it to accelerate freely. This inversion eliminates the compression states that cause dimensional defects while maintaining high productivity through the efficient release mechanism at the end of the rolling process.

Inventive Principle:

Principle #13The other way round (Inversion)

3Productivity

If a floating mandrel rolling mill operates at high speed, then productivity increases, but temperature uniformity along the tube becomes non-uniform requiring downstream heating ovens

Engineering Contradiction:

Improverolling speedVSAvoidtube temperature uniformity

Core Design Contradiction:

ProductivityVSTemperature

Solution Approach 1:

The patent inverts the mandrel speed control strategy by maintaining constant mandrel speed during rolling rather than allowing acceleration. This ensures uniform temperature distribution along the tube length since the mandrel moves at consistent speed, eliminating the need for downstream heating ovens while maintaining high productivity through the release-based retention system.

Inventive Principle:

Principle #13The other way round (Inversion)

4Ease of operation

If chain and sprocket mandrel conveying systems are used, then mandrel can be conveyed, but components experience premature wear and risk of mandrel damage at high speeds

Engineering Contradiction:

Improvemandrel conveyanceVSAvoidcomponent durability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent replaces the chain and sprocket mechanical system with a direct rack and pinion engagement system. The pinion gears engage directly with the rack on the mandrel, eliminating the intermediate chain and sprockets that caused premature wear and reliability issues. This substitution maintains ease of mandrel conveyance while significantly improving component durability and reducing risk of mandrel damage at high speeds.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 solution enhances productivity, allows for rolling of tubes of varying lengths, particularly shorter tubes, and improves tube quality by reducing wall thickness and eliminating the need for intermediate heating, while ensuring mandrel safety and stability.

Implementation Method 1

The rack device comprises two racks side-by-side, parallel to the rolling axis, each of said two racks has two respective gear teeth

Methodology Applied

Scientific EffectGear mechanism: Gear

Implementation Method 2

a hooking and releasing device for hooking and for releasing a tang of the mandrel

Methodology Applied

Scientific EffectMechanical fastening: Mechanical Fastener

Data Source

PatentUS10052669B2Mandrel conveying device for a tube rolling mill

Publication Date: 2018.08.21 DANIELI & C OFFICINE MECCANICHE SPA

AI summary

A rolling plant (R) for rolling tubes having a multi-stand rolling mill (5) with two or more rolls, in order to implement a controlled speed mandrel rolling process, comprises a hooking and releasing device (61) which is arranged in the inlet area of the rolling mill (5) to cooperate with the rear tang of the mandrel (31) and a hooking and releasing device (71) which is arranged in the outlet area of the rolling mill (5) to cooperate with the front tang of the mandrel (31) in coordinated manner with the first hooking and releasing device (61).