Preface

You have just opened the book "Machine tools - design, research and applications". Machine tools are systems designed to create workpieces of a particular shape, dimension and machining quality. For this purpose machine tools have to create cutting motions that consist of the mutual coupling of vectors of rotary motion and translational motion. Today, we encounter machine tools everywhere and we cannot imagine life without them.

An important role in the development of today's type of machine tools was played by the rolling bearing patent obtained by the Englishman Philip Vaughan in 1794 and, three years later, by the rediscovery of the lathe by his compatriot Henry Maudslay.

The development and application of new, highly productive cutting tools made of cutting ceramics, natural or synthetic diamonds and other synthetic super hard materials allowed a significant increase in the values of cutting speeds. The pioneer of high-speed machining is considered to be the German researcher Carl Salamon, who in 1920 milled steel at the cutting speed of 440 m.min−1, and aluminium at up to 16 500 m.min−1. This significantly reduced overall machining times, increased machine productivity and production efficiency.

The productivity of the machine tool is characterized by the number of manufactured parts along with the size of the machined area and the volume of material used. Productivity is limited by the mean thickness of the chips and it depends on cutting and feed speeds. Moreover, the cutting speed depends mostly on the frequency of rotation of the headstock of the machine tool. This is the reason for the ongoing increase in mean revolution frequencies, the ever more frequent application of headstocks with integrated drive, the so-called "Electro-spindle" and the shift from classic to high-speed machining.

In proportion to the growth of living standards, the speed, quantity and variety of requirements for the quality and accuracy of manufactured products have increased. The means to achieve the required accuracy of the machine tool is by optimizing the structure in terms of stiffness and dynamic stability.

Therefore, in addition to increasing the productivity of machine tools, it is of the utmost importance to pay special attention to optimizing the design of the machine in terms of rigidity, thermal expansion, variability and chip removal at large volumes of machined material. Therefore, when designing and optimizing the construction of machines, we increasingly resort to virtual prototyping and computer analysis of the functional properties of the proposed machine.

The basic condition for achieving the required machine tool accuracy, as well as that of the machined parts, is the rigidity of the "machine - tool - preparation workpiece" system. Apart from rigidity, this system is influenced by the geometric accuracy of the machine, the technological approach, the strategy for measuring the work piece and the servicing of the machine. With classical machine tool designs, this refers to the serial structure of arranging the motion axes, where the total rigidity of the system is limited by the machine's weakest construction node. In machine tools with moving rotation, this generally is the motion axis carrying the workpiece, or the tool carrier - against the headstock.

It is clear that such productivity and accuracy of machine tools depends mostly on the quality of the headstock and other structural elements, such as guide parts, drives, frame and other nodes. Both of these criteria act in a contradictory manner. With the requirement for increased headstock frequency and feed speed, production does increase. However, at the same time the positional rigidity of the headstock and of the motion mechanisms – in other words, machine work precision – decreases. From the viewpoint of productivity and accuracy of work we can regard the headstock as the heart of the whole machine tool, influencing the quality of work to a decisive degree.

Among the other important quality criteria is the mechanical design or modularity of the machine tool, or of the production system. The modular state of the construction is an important precondition for the competitiveness of the product on the market. The basis of this concept is the system of modules from which various configurations can be created, in line with the specific demands of the client. On the part of the producer, the manufacture of the machines will be made more effective, while, on the other hand, the client will be paying for a functional machine that he really needs and uses.

An inseparable component in the selection of a suitable machine is risk management and a current analysis of the functionality and reliability of the machine's work. Based on this analysis, we are able to continue with a computer optimization of the mutual spatial arrangements of the configuration "machine - tool preparation - workpiece" system to achieve the maximum work safety of the existing machine.

In recent times, it has become a matter of course to include, within the added value for the mechanical and electronic construction of the CNC machining tool, the capacity to compensate for inaccuracy over the whole working area – so-called volumetric compensation. Indeed, it has been shown that contemporary mechanical construction has reached its potential limits in the current period, unless some new principle is discovered. For this reason, in addition to heat stabilization of the machine, one of the alternatives for increasing precision of work is to increase volumetric precision through spatial compensations. This will require familiarity with the perfect geometric precision of the tool, which is influenced by the manufacture of the individual pieces of the motion axis and their assembly, involving all the axes at once.

This book is divided into three basic sections and seven chapters presenting both theoretical and experimental work. Chapters 1-3 cover trends in the development of machine tool construction. Chapters 4-6 deal with the research and development of system rigidity, and the measuring of the accuracy of the machine tools.

**V**

Chapter 7 presents an example of the application of machine tools in the

development.

production of orthopaedic aids. The work presented in the book is of considerable relevance and use to researchers working in the area of design, research and

**Dr.h.c. prof. Ing Ľubomír Šooš, PhD.**

Slovak University of Technology Bratislava,

Faculty of Mechanical Engineering,

Brno University of Technology,

Dean,

Slovakia

Czechia

**Jiri Marek** Professor, Chapter 7 presents an example of the application of machine tools in the production of orthopaedic aids. The work presented in the book is of considerable relevance and use to researchers working in the area of design, research and development.

> **Dr.h.c. prof. Ing Ľubomír Šooš, PhD.** Dean, Faculty of Mechanical Engineering, Slovak University of Technology Bratislava, Slovakia

> > **Jiri Marek** Professor, Brno University of Technology, Czechia

**IV**

accuracy of the machine, the technological approach, the strategy for measuring the work piece and the servicing of the machine. With classical machine tool designs, this refers to the serial structure of arranging the motion axes, where the total rigidity of the system is limited by the machine's weakest construction node. In machine tools with moving rotation, this generally is the motion axis carrying the

It is clear that such productivity and accuracy of machine tools depends mostly on the quality of the headstock and other structural elements, such as guide parts, drives, frame and other nodes. Both of these criteria act in a contradictory manner. With the requirement for increased headstock frequency and feed speed, production does increase. However, at the same time the positional rigidity of the headstock and of the motion mechanisms – in other words, machine work precision – decreases. From the viewpoint of productivity and accuracy of work we can regard the headstock as the heart of the whole machine tool, influencing the

Among the other important quality criteria is the mechanical design or modularity of the machine tool, or of the production system. The modular state of the construction is an important precondition for the competitiveness of the product on the market. The basis of this concept is the system of modules from which various configurations can be created, in line with the specific demands of the client. On the part of the producer, the manufacture of the machines will be made more effective, while, on the other hand, the client will be paying for a functional machine that he

An inseparable component in the selection of a suitable machine is risk management and a current analysis of the functionality and reliability of the machine's work. Based on this analysis, we are able to continue with a computer optimization of the mutual spatial arrangements of the configuration "machine - tool preparation - workpiece" system to achieve the maximum work safety of the

In recent times, it has become a matter of course to include, within the added value for the mechanical and electronic construction of the CNC machining tool, the capacity to compensate for inaccuracy over the whole working area – so-called volumetric compensation. Indeed, it has been shown that contemporary mechanical construction has reached its potential limits in the current period, unless some new principle is discovered. For this reason, in addition to heat stabilization of the machine, one of the alternatives for increasing precision of work is to increase volumetric precision through spatial compensations. This will require familiarity with the perfect geometric precision of the tool, which is influenced by the manufacture of the individual pieces of the motion axis and their assembly,

This book is divided into three basic sections and seven chapters presenting both theoretical and experimental work. Chapters 1-3 cover trends in the development of machine tool construction. Chapters 4-6 deal with the research and development of system rigidity, and the measuring of the accuracy of the machine tools.

workpiece, or the tool carrier - against the headstock.

quality of work to a decisive degree.

really needs and uses.

existing machine.

involving all the axes at once.

**1**

Section 1

Design and Trend
