First, the definition of machine toolsMachine tools are machines that process blanks or workpieces of metal or other materials to achieve the required geometry, dimensional accuracy and surface qualit...
First, the definition of machine tools
Machine tools are machines that process blanks or workpieces of metal or other materials to achieve the required geometry, dimensional accuracy and surface quality.
Mechanical parts are usually machined out of the machine. The machine is the machine that makes the machine and the machine that makes the machine itself, which is the main feature that distinguishes the machine from other machines, so the machine is also known as the working machine or machine tool.
Second, the classification of machine tools
Metal cutting machine tools, mainly for metal cutting;
Woodworking machine for cutting wood processing;
Special processing machine tools, with physical, chemical and other methods of special processing of the workpiece;
Forging machinery. Narrow machine only refers to the most widely used, the largest number of metal cutting machine tools.
1, metal cutting machine can be divided according to different classification methods for many types.
1.1 by processing or processing object can be divided into lathe, drilling machine, boring machine, grinding machine, gear processing machine, thread processing machine, spline processing machine, milling machine, planer, slotting machine, broaching machine, special processing machine, sawing machine and engraving machine . Each class is divided into several groups according to their structure or processing object, each group is divided into several types.
1.2 by the size of the workpiece and machine weight can be divided into instrumentation machine tools, small and medium sized machine tools, large machine tools, heavy machine tools and super heavy machine tools;
1.3 according to the processing accuracy can be divided into ordinary precision machine tools, precision machine tools and high-precision machine tools;
1.4 by the degree of automation can be divided into manual operation of machine tools, semi-automatic machine tools and automatic machine tools;
1.5 According to the automatic control of machine tools, can be divided into profiling machine tools, program control machine tools, digital control machine tools, adaptive control machine tools, machining centers and flexible manufacturing systems;
1.6 by the machine's scope of application, but also can be divided into general, specialized and special machine tools.
1.7 Special machine tools in a standard common parts, with a small amount of special parts according to the specific shape of the workpiece or process design of the composition of automatic or semi-automatic machine tools, known as the combination of machine tools.
1.8 pairs of one or several parts of the processing, according to the process has arranged a series of machine tools, coupled with automatic loading and unloading devices and machine tools and automatic transfer of parts between the workpiece, so composed of a group of machine tools known as cutting automatic production lines.
1.9 Flexible Manufacturing System is composed of a group of digital control machine tools and other automated process equipment. It is controlled by electronic computer and can automatically process the workpieces with different processes to adapt to multi-varieties production.
Machine tool is the basic production equipment of machinery industry, its variety, quality and processing efficiency directly affect the production of other mechanical products, technical level and economic benefits. Therefore, the level and size of the modernization of the machine tool industry, as well as the number and quality of the machine tools owned are one of the important symbols of a country's industrial development.
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Third, a brief history of the development of machine tools
The tree lathe that appeared more than 2000 BC is the earliest prototype of the machine tool. Work, the lower end of the pedal rope rings, the use of the flexibility of the branches so that the workpiece driven by the rope rotation, holding shells or stone as a tool, along the slats move the tool to cut the workpiece. The medieval elastic rod lathe is still used in this principle.
In the fifteenth century, due to the need to manufacture clocks and weapons, thread lathes and gear-processing machines used by watchmakers, as well as hydraulically actuated barrel boring machines appeared. Around 1500, the Italian Leonardo da Vinci sketched out sketches of lathes, boring machines, thread-processing machines and internal grinding machines, with new mechanisms such as cranks, flywheels, shanks and bearings. China's Ming Dynasty published "Heavenly Creations" also contains the structure of the grinder, with the method of rotating iron plate, coupled with sand and water cut jade.
The industrial revolution of the eighteenth century drove the development of machine tools. In 1774, the British Wilkinson invented a more sophisticated barrel boring machine. The following year, he used the boring cylinder boring machine to meet the requirements of the Watt steam engine. In order to bore a larger cylinder, he again built a water-driven cylinder boring machine in 1776, fueling the development of the steam engine. Since then, the machine began to use the steam engine driven by the dayshaft.
In 1797, the English-made Maudsley lathe was driven by a screwdriver to allow for maneuvering and turning. This was a major change in machine tool construction. Maudsley is also known as the "father of the British machine tool industry."
In the 19th century, due to the promotion of textile, power, transportation machinery and arms production, various types of machine tools appeared in succession. In 1817, the British Roberts created a planer; Whitney made in 1818 the American horizontal milling machine; 1876, the United States made universal cylindrical grinder; 1835 and 1897 has invented the hobbing machine and gear shaper.
With the invention of the motor, the machine tool was first driven by a motor and then by a separate motor. At the beginning of the twentieth century, coordinate boring machines and thread grinding machines were successively established for the purpose of machining parts, fixtures and thread processing tools with higher precision. At the same time in order to meet the automotive and bearing industries such as mass production needs, but also developed a variety of automatic machine tools, copying machine tools, machine tools and automatic assembly line.
With the development of electronic technology, the United States developed the first digital control machine tool in 1952; in 1958, it developed a machining center that can automatically change tools for multi-process machining. Since then, with the development and application of electronic technology and computer technology, the machine tool has undergone significant changes in terms of driving mode, control system and structural functions.
Fourth, the work of machine tools
Machine tool cutting is achieved by the relative movement between the tool and the workpiece, the movement can be divided into two types of surface movement and auxiliary movement.
Surface-forming motions are the motions that give the workpiece the desired surface shape and dimensions, including the main motions, the feed motions and the plunge motions. The main movement is the main movement from which the excess material is peeled off from the workpiece blank. It can be a rotary movement of a workpiece (such as turning), a linear movement (such as planing on a planer), or a rotary movement Milling and drilling) or linear movement (such as cutting and broaching); Feed movement is the tool and the workpiece to be machined part of the relative movement to enable the cutting to continue the movement, such as turning the outer cylinder knife slide along the machine guide rail And so on; cutting into the movement is to cut into the workpiece surface depth of the movement, its role is in each cutting stroke from the workpiece surface cut a certain thickness of material, such as the turning of the small turret lateral cut into the movement.
Auxiliary movements include the rapid approach and exit of the tool or workpiece, the adjustment of the position of the machine tool parts, the indexing of the workpiece, the turret indexing, the feed, the start, the speed change, the commutation, the stop and the automatic tool change.
Various types of machine tools are usually composed of the following basic components: support components for the installation and support of other components and parts, to withstand its weight and cutting force, such as bed and column, etc .; variable speed mechanism for changing the speed of the main movement; feed Mechanism for changing the feed rate; spindle box for installing the machine tool spindle; tool holder, tool magazine; control and control system; lubrication system; cooling system.
Machine tool attachments include machine tool attachments such as machine loading / unloading devices, robotics and industrial robots, as well as machine tool attachments such as chuck, chuck collet, vice, swivel table and indexing head.
Evaluation of machine tool performance indicators can be attributed to the final machining accuracy and production efficiency. Processing accuracy includes the dimensional accuracy of the workpiece being machined, shape accuracy, position accuracy, surface quality and machine tool accuracy retention. Production efficiency involves cutting and auxiliary machining times as well as machine tool automation and operational reliability. These indicators depend on the one hand, the static characteristics of the machine tool, such as static geometry accuracy and stiffness; and on the other hand with the dynamic characteristics of machine tools such as motion accuracy, dynamic stiffness, thermal deformation and noise more.
Fifth, the future development trend of machine tools
The future development trend of machine tool is:
The further application of computer technology, new servo drive components, optical grating and optical fiber and other new technologies to simplify the mechanical structure, improve and expand the function of automation work to make the machine adapted to be included in the flexible manufacturing system;
Improve the power of the main movement and the speed of the feed movement, corresponding to improve the structure of the dynamic and static stiffness to meet the needs of the new tool to improve cutting efficiency;
Improve machining precision and develop ultra-precision machining machine tools to meet the needs of emerging industries such as electromechanical and aerospace industries; and develop special-purpose machine tools to handle the machining of difficult-to-machine metal materials and other new industrial materials.