Steel Rolling

Principle, Process & Application

N.K. Gupta

• Publisher: CRC Press
• Year: 2021
• ISBN:
  9781000401745
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Mining Engineering
• Index: Technology & Engineering

This book covers all aspects and elements of rolling technology in one volume with even the most technical jargon being communicated in an easy to understand language. The book is exhaustive as topics ranging from rolls, rolls cooling, roll turning, roll reclamation, investigation of roll breakage, roll management and roll bearing all have been dealt in detail as these constitute the most important element of production cost. A separate chapter has been dedicated to operational management of a rolling mill, which includes safety and inventory. Packaging of the finished products and modern operating mill practices and technologies are also discussed in detail. This book will be a useful tool for shop floor personnel and for all senior management operating in the rolling mill industry; it is also a must read for all polytechnic / engineering students of metallurgical / mechanical / process engineering.
This book may also be useful as reference book for students/professionals of rolling technology.

Note: T&F does not sell or distribute the Hardback in India, Pakistan, Nepal, Bhutan, Bangladesh and Sri Lanka.

1
Roll Pass Design

1 INTRODUCTION

The highly increased demand of steel by all the sectors of industries, construction and agriculture, has necessitated for the development of a variety of rolled products with the change in metal rolling technology.

The ultimate goal of a roll pass designer has to ensure the production of a desired shaped product with appropriate internal structure and are with desired mechanical properties. The product should be defect free surface with good surface finish and should have to produced with lowest cost of production.

Fig. 1.1 Rolling of a Product in a Rolling Mill.

2 ROLL PASS DESIGN

2.1 Object of Roll Pass Design

Steel sections are generally rolled in several passes, whose number is determined by the ratio of initial input material and final cross section of finished product. The cross section area is getting reduced in each subsequent passes and gradually the form and size of the stock approaches to the shape of designed profile.

Plates, sheets and flats are rolled in plain-barreled roll. Here the thickness of the stock getting rolled is reduced in each passing by reducing the gap between rolls.

Steel sections and shapes are rolled in grooved rolls, i.e., the annular slot cut in a single roll. The profile of this slot is referred as the “Groove or Roll Groove”.

Roll pass design means the calculation and design of the rolling schedule and passes to obtain a given rolled section, as well as to design the rolls to accommodate these passes.

2.2 Basic Purpose of Roll Pass Design

• To shape the metal to the designed profile.
• The profile design indicates a system of consecutive passes to produce the profile to the desired size and shape within the stipulated tolerance limit and with the specified mechanical properties and surface finish.
• Pass design also provides the shape and size of changing cross section of rolled material at every rolling stage.
• It locates the passes on the roll by designing rolls, working and non-working collars and also specifies the roll material etc.
• Pass design provides the highest possible production capacity of the rolling mill with minimum cost of rolled production.
• Pass design also ensures the smooth entry and exit of the strip and guaranteed the strength of rolls and motor capacity.

In the case of flat rolling (for slabs, sheets, strips), the pass designer has to provide the solution of the concerned problems with the distribution of reduction. According to the number of passing available and to make the sequence of rolling of flats with different sizes, to be rolled in that particular barrel. Such optimum schedule will help to minimize the frequency of the roll changing and to get the maximum production.

2.3 Characteristics of Efficient Roll Pass Design

• To make a profile with a smooth surface and of a correct dimensions within the stipulated limits of standard.
• To ensure the minimum expenses of energy, power and roll consumption.
• To give deformation in such a way to generate minimum internal stress in the finished product.
• To create a simple and convenient work culture in shop floor of rolling mill, which has to minimize the manual operation to the minimum possible extend to introduce the automation of technological process.
• To optimize number of passes, which required for rolling, to reduce the total rolling time cycle, with the minimum time spent for changing and adjusting of rolls.

2.4 Specified Conditions Under Which Roll Pass Design is Based Upon

• Characteristics of finished product i.e., dimension of section, tolerances and specifications concern to mechanical properties and surface finish of rolled product.
• Characteristics of initial input material i.e., dimension and weight of billet, grade of steel and the metal temperature before a...