1.Definition of machine tool

A machine tool is a machine that processes blanks or workpieces of metal or other materials to obtain the required geometric shape, dimensional accuracy and surface quality.

The parts of mechanical products are usually made by machine tools. Machine tool is the machine that makes machine, also is the machine that can make machine tool itself, this is the main characteristic that machine tool differs from other machine, so machine tool is also called working mother machine or tool machine.

2.Classification of machine tools

Metal cutting machine tools, mainly used for metal cutting; woodworking machine tools, used for wood cutting; special processing machine tools, with physical, chemical and other methods on the workpiece for special processing; forging machinery. The narrow sense of machine tools only refers to the most widely used, the largest number of metal cutting machine tools.

1. Metal cutting machine tools can be divided into many types according to different classification methods. 

1.1 according to the processing mode or the processing object may divide into the lathe, the drilling machine, the boring machine, the grinder, the gear processing machine, the thread processing machine, the spline processing machine, the milling machine, the Planer, the slotting machine, the broaching machine, the special processing machine, the saw machine and the cutting line machine and so on. Each category is further divided into groups according to its structure or processing objects, and each group is further divided into types.

 1.2 machine tools can be divided into instrument machine tools, medium and small machine tools, large machine tools, heavy machine tools and super heavy machine tools according to the size of workpieces and the weight of machine tools 

1.3 machine tools can be divided into ordinary precision machine tools, precision machine tools and high precision machine tools according to the machining accuracy; 

1.4 according to the degree of automation can be divided into hand-operated machine tools, semi-automatic machine tools and automatic machine tools; 

1.5 according to the automatic control mode of machine tools, can Be divided into copying machine tools, program control machine tools, digital control machine tools, adaptive control machine tools, machining centers and flexible manufacturing systems; 

1.6 according to the scope of application of machine tools, can be divided into general, specialized and special machine tools. 

1.7 a special purpose machine tool consists of an automatic or semi-automatic machine tool that is based on a standard universal component and consists of a small number of special components designed for the particular shape or process of the workpiece. It is called a modular machine tool. 

1.8 for the machining of one or more parts, a series of machine tools shall be arranged in sequence according to the working procedure, and shall be equipped with automatic loading and unloading devices and automatic transfer devices between the machine tools and the machine tools, such a group of machine tools is called automatic cutting production line. 

1.9 The fms consists of a set of numerically controlled machine tools and other automated process equipment, controlled by computer, which can automatically process parts with different processes and can be adapted to a wide variety of production. Machine tool is the basic production equipment of mechanical industry. Its variety, quality and processing efficiency directly affect the production technology level and economic benefit of other mechanical products. Therefore, the modernization level and scale of machine tool industry, as well as the quantity and quality of machine tool owned is one of the important signs of a country's industrial development degree. A brief history of the development of machine tools the tree lathe, which appeared more than 2000 BC, was the earliest embryonic form of machine tools. When working, the foot steps on the loop at the lower end of the rope, making use of the elasticity of the tree branch to make the work piece rotate driven by the rope, holding the shell or the stone piece as a tool, and moving the tool along the lath to cut the work piece. The medieval elastic rod-and-rod lathes still use this principle. In the 15th century, for the purpose of making clocks and weapons, there were screw and gear turning machines for watchmakers and hydraulic boring machines for gun barrels. Around 1500, Italian Leonardo sketched out the idea for lathes, boring machines, threading machines and internal grinding machines, including new mechanisms such as cranks, flywheels, neck tips and bearings. The structure of the Tchien-kung kchaj-wu, published in the Ming Dynasty in China, also contained grinding machines that rotated iron plates with pedals, added sand and water, and cut jade. The Industrial Revolution of the Eighteenth Century gave impetus to the development of machine tools. 1774, British Wilkinson invented a more sophisticated barrel boring machine. The following year, he used this barrel boring machine to bore out the cylinder to meet the requirements of the Watt steam engine. In order to boring larger cylinders, he also made a hydraulic cylinder boring machine in 1776, promoting the development of the steam engine. From then on, the machine tool was driven by a steam engine through a skyshaft. 1797, a British lathe created by Mozley by the lead screw drive tool holder, can be motorized feed and turning thread, this is a major change in the structure of machine tools. Mozley became known as 'the father of the British machine tool industry' . In the 19th century, various types of machine tools came into being, driven by textiles, power, transportation machinery and arms production. 1817, British HMS Roberts Invented Planer; 1818 Witney Made Horizontal Milling Machine; in 1876, the United States made a universal cylindrical grinder; in 1835 and 1897, and then invented hobbing machine and gear shaper. With the invention of the electric motor, the machine tool first used the electric motor to drive centrally, then widely used the single electric motor to drive. At the beginning of the 20th century, coordinate boring machines and thread grinding machines were invented in order to produce more precise workpiece, fixture and thread processing tools. At the same time, in order to meet the needs of automobile and bearing industry, various automatic machine tools, copying machine tools, modular machine tools and automatic production lines have been developed. With the development of electronic technology, the United States in 1952 developed the first digital control machine tool; in 1958 developed automatic tool replacement to carry out multi-process machining center. Since then, with the development and application of electronic technology and computer technology, significant changes have taken place in the driving mode, control system and structure and function of machine tools.

3.A brief history of machine tool development

The tree lathe, which appeared more than 2000 BC, was the earliest embryonic form of machine tools. When working, the foot steps on the loop at the lower end of the rope, making use of the elasticity of the tree branch to make the work piece rotate driven by the rope, holding the shell or the stone piece as a tool, and moving the tool along the lath to cut the work piece. The medieval elastic rod-and-rod lathes still use this principle.

In the 15th century, for the purpose of making clocks and weapons, there were screw and gear turning machines for watchmakers and hydraulic boring machines for gun barrels. Around 1500, Italian Leonardo sketched out the idea for lathes, boring machines, threading machines and internal grinding machines, including new mechanisms such as cranks, flywheels, neck tips and bearings. The structure of the Tchien-kung kchaj-wu, published in the Ming Dynasty in China, also contained grinding machines that rotated iron plates with pedals, added sand and water, and cut jade.

The Industrial Revolution of the Eighteenth Century gave impetus to the development of machine tools. 1774, British Wilkinson invented a more sophisticated barrel boring machine. The following year, he used this barrel boring machine to bore out the cylinder to meet the requirements of the Watt steam engine. In order to boring larger cylinders, he also made a hydraulic cylinder boring machine in 1776, promoting the development of the steam engine. From then on, the machine tool was driven by a steam engine through a skyshaft.

1797, a British lathe created by Mozley by the lead screw drive tool holder, can be motorized feed and turning thread, this is a major change in the structure of machine tools. Mozley became known as 'the father of the British machine tool industry' .

In the 19th century, various types of machine tools came into being, driven by textiles, power, transportation machinery and arms production. 1817, British HMS Roberts Invented Planer; 1818 Witney Made Horizontal Milling Machine; in 1876, the United States made a universal cylindrical grinder; in 1835 and 1897, and then invented hobbing machine and gear shaper.

With the invention of the electric motor, the machine tool first used the electric motor to drive centrally, then widely used the single electric motor to drive. At the beginning of the 20th century, coordinate boring machines and thread grinding machines were invented in order to produce more precise workpiece, fixture and thread processing tools. At the same time, in order to meet the needs of automobile and bearing industry, various automatic machine tools, copying machine tools, modular machine tools and automatic production lines have been developed.

With the development of electronic technology, the United States in 1952 developed the first digital control machine tool; in 1958 developed automatic tool replacement to carry out multi-process machining center. Since then, with the development and application of electronic technology and computer technology, significant changes have taken place in the driving mode, control system and structure and function of machine tools.

4.Machine work

The machining of the machine tool is realized by the relative motion between the tool and the workpiece. The motion can be divided into surface forming motion and auxiliary motion.

Surface forming motion is the motion that enables the workpiece to obtain the required surface shape and size, which includes main motion, feed motion and cut-in motion. The main motion is the one that plays a major role in removing excess material from a workpiece blank. It may be the rotational motion of the workpiece such as turning, or the linear motion such as planing on a Gantry Planer, it may also be the rotary motion of the tool, such as milling and drilling, or the linear motion, such as slotting and broaching; the feed motion is the motion of the tool and the part to be worked against each other, so that the cutting can continue, for example, when turning an outer circle, the tool carrier plate moves along the guide rail of the machine tool; the cutting motion is the motion that causes the tool to cut a certain depth into the surface of the workpiece. Its function is to cut a certain thickness of material from the surface of the workpiece during each cutting stroke, such as turning the outer circle when the tool holder of the transverse cutting movement.

The auxiliary motion mainly includes the fast approaching and withdrawing of the cutting tool or workpiece, the adjustment of the parts position of the machine tool, the indexing of the workpiece, the turning of the tool holder, the feeding of the clamping material, the starting, changing the speed, reversing, stopping and the automatic changing of the cutting tool, etc. 

Each type of machine tool is usually composed of the following basic parts: Supporting Parts for mounting and supporting other parts and workpieces, bearing their weight and cutting forces, such as the bed and columns; speed-changing mechanisms for changing the speed of the main motion; and feeding mechanisms, for changing feed rate; headstock for Mounting Machine spindle; tool carrier, tool magazine; control and Control System; Lubrication System; cooling system.

Machine tool accessory includes machine tool accessory such as machine tool loading and unloading device, manipulator, industrial robot, and machine tool accessory such as chuck, Chuck Chuck Chuck Spring Chuck, vise, Rotary Table and indexing head.

The index of evaluating the technical performance of machine tools can be reduced to machining accuracy and production efficiency. The machining accuracy includes the size accuracy, shape accuracy, position accuracy, surface quality and accuracy retention of the machine tool. Production efficiency is related to cutting time and auxiliary time, as well as the degree of automation and reliability of machine tools. On the one hand, these indexes depend on the static characteristics of the machine tool, such as static geometric accuracy and stiffness, and on the other hand, they are more related to the dynamic characteristics of the machine tool, such as kinematic accuracy, dynamic stiffness, thermal deformation and noise.

5.Future development trend of machine tool

The future of machine tools is:

Further application of new technologies such as computer, new servo drive elements, Raster and optical fiber simplifies the mechanical structure, improves and expands the functions of automation, and adapts the machine to work in a flexible manufacturing system;

The speed of the main motion and the feed motion of the power is increased, and the dynamic and static stiffness of the structure is correspondingly increased to meet the need of adopting new-type cutting tools and to improve the cutting efficiency

To improve machining accuracy and develop ultra-precision machining machine tools to meet the needs of emerging industries such as electronic machinery and aerospace; to develop special machining machine tools to adapt to the processing of difficult-to-process metal materials and other new industrial materials.