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HISTORY OF TECHNOLOGY, TECHNOLOGY, OBJECTS AROUND US
Lathe. History of invention and production
Directory / The history of technology, technology, objects around us Lathe - a machine for cutting (turning) workpieces made of metals, wood and other materials in the form of bodies of revolution. On lathes, they perform turning and boring of cylindrical, conical and shaped surfaces, threading, trimming and end processing, drilling, countersinking and reaming holes, etc. The workpiece receives rotation from the spindle, the cutter - the cutting tool - moves along with the caliper slide from drive shaft or lead screw, which receives rotation from the feed mechanism.
In the XVII-XVIII centuries. manufacturing industry flourished. Many manufactories had metalworking workshops. Processing in the workshops was carried out mainly on lathes. In these machines, a flexible pole was fixed on top, to which one end of the rope was tied. The rope wrapped around the roller on the machine. The other end was attached to the board, which was the pedal for the worker's foot. By pressing the pedal, the worker rotated the roller and the workpiece. He held a cutting tool in his hand. The lathe was a complex tool, but not a machine. To turn into a machine, a tool holder-caliper was needed, replacing a human hand. The Russian mechanic A.K. Nartov became the inventor of the lathe with a caliper. He built several lathes that had a mechanical support-holder. On machines designed by Nartov, a wheel driven by water or animal power could be used to drive. Despite the remarkable work of Nartov and the high appreciation that his inventions and knowledge received, the caliper he invented did not have much influence on the practical development of turning technology. At the end of the XVIII century. the idea of using a caliper in lathes was returned in France. In the "French Encyclopedia" Diderot in 1779, a description is given of a fixture for lathes, which clearly resembles the principle of a caliper. However, these machines had a number of shortcomings that precluded their widespread use in practice. The possibility of developing engineering technology appeared only as a result of the first two stages of the industrial revolution. For the machine production of machines, a powerful engine was needed. By the beginning of the XIX century. such an engine was a universal double-acting steam engine. On the other hand, the development of the production of working machines and steam engines in the second half of the XNUMXth century. formed qualified personnel for mechanical engineering - mechanical workers. These two conditions ensured the technical revolution in mechanical engineering. The beginning of a change in the technique of manufacturing machines was laid by the English mechanic Henry Maudsley, who created a mechanical support for a lathe. Maudsley began working at the London Arsenal at the age of twelve. There he acquired good skills in woodworking and metalworking and, in addition, became a master blacksmith. However, Maudsley dreamed of a career as a mechanic. In 1789 he entered the London machine shop of Joseph Brum, a specialist in the manufacture of locks. In Bram's workshop, G. Maudsley had the opportunity to invent and design various devices for making locks. In 1794, he invented the so-called cross support for a lathe, which contributed to the transformation of the machine into a working machine. The essence of Maudsley's invention boiled down to the following: turners, turning any object, tightly strengthened it on the machine with special clamps. The working tool - the cutter was at the same time in the hands of the worker. When the shaft rotated, the cutter processed the workpiece. The worker had to not only create the necessary pressure with a cutter on the workpiece, but also move it along it. This was possible only with great skill and strong tension. The slightest shift of the cutter violated the accuracy of turning. Maudsley decided to strengthen the cutter on the machine. To do this, he created a metal clamp - a caliper, which had two carriages that move by means of screws. One carriage created the necessary pressure of the cutter on the workpiece, and the other moved the cutter along the workpiece. Thus, the human hand was replaced by a special mechanical device. With the introduction of the caliper, the machine began to operate continuously with perfection, unattainable even for the most skillful human hand. The caliper could be used for the manufacture of both the smallest parts and huge parts of various machines. This mechanical device has replaced not any tool, but the human hand, which creates a certain form, bringing it closer, applying the tip of a cutting tool or directing it to the material of labor, such as wood or metal. Thus, it was possible to reproduce the geometric shapes of individual parts of machines with such ease, accuracy and speed that the hand of the most experienced worker could never provide. The first machine tool with a caliper, though extremely imperfect, was made in Bram's workshop in 1794-1795. In 1797, Maudsley built the first workable lathe on a cast-iron bed with a self-propelled caliper. The machine was used for cutting screws, and was also used for processing parts of locks. In the future, Modesi continued to improve the lathe with a caliper. In 1797, he built a screw-cutting lathe with a replaceable lead screw. Dressing screws in those days was an extremely difficult job. Screws, cut by hand, had a completely arbitrary thread. It was difficult to find two identical screws, which made it extremely difficult to repair machines, assemble them and replace worn parts with new ones. Therefore, Maudsley primarily improved screw-cutting lathes. Through his work on improving the threads of screws, he achieved a partial standardization of the manufacture of screws, paving the way for his future student Whitworth, the founder of screw standards in England.
Self-propelled machine Maudsley, offered for screw-cutting work, soon proved to be an indispensable machine in any turning work. This machine worked with amazing accuracy, without requiring much physical effort on the part of the worker. Attempts to create a working machine in mechanical engineering since the end of the XNUMXth century. were made in other countries. In Germany, the German mechanic Reichenbach, independently of Maudsley, also proposed a device for holding a cutter (caliper) on a wooden lathe designed for processing precision astronomical instruments. However, the economic development of feudal Germany lagged far behind that of capitalist England. The mechanical support of handicraft German industry was not needed, while the introduction of the Maudsley screw-cutting lathe in England was due to the needs of developing capitalist production. The caliper was soon turned into a perfect mechanism and transferred in a modernized form from the lathe, for which it was originally intended, to other machines used to make machines. With the manufacture of the caliper, all metalworking machines begin to improve and turn into machines. Mechanical revolving, grinding, planing, milling machines appear. By the 30s of the XIX century. English mechanical engineering already had the main working machines that made it possible to mechanically perform the most important operations in metalworking. Soon after the invention of the caliper, Maudsley left Brahm and opened his own machine shop, which quickly turned into a large machine-building plant. The Maudsley plant played an outstanding role in the development of English machine technology. It was the school of famous English mechanics. Here such outstanding machine builders as Whitworth, Roberts, Nesmith, Clement, Moon and others began their activities. At the Maudsley plant, a machine system of production was already used in the form of a connection by transmissions of a large number of working machines set in motion by a universal heat engine. The Model Factory mainly produced parts for Watt's steam engines. However, the plant also designed work machines for mechanical workshops. G. Maudsley produced exemplary turning and then planing machine tools. Model himself, despite the fact that he was the owner of a large enterprise, worked all his life on a par with his workers and students. He had an amazing ability to find and nurture talented machine builders. Many prominent English mechanics owe their technical education to Maudsley. In addition to the caliper, he made many inventions and improvements in a wide variety of branches of technology.
On a rigid base 1, which is called the bed, the headstock 5 and the tailstock 2 are fixed. The headstock is fixed. Its main unit is the shaft-spindle 8. It rotates in bronze bearings inside a fixed housing 7. A device for fastening the workpiece is installed on the spindle. In this case, this is a fork 9. Depending on its size and shape, a faceplate, a cartridge and other devices are also used to clamp the part. The spindle rotates from the electric motor 10 through the drive pulley 6. The tailstock of the machine can move along the bed and is fixed in the desired position. At the same level with the spindle of the headstock, the so-called center 11 is installed in the tailstock. This is a roller with a pointed end. The tailstock is used when machining long parts - then the workpiece is clamped between the spindle fork and the center of the tailstock. A modern lathe consists of working bodies - a support for mounting a cutter, a spindle for mounting a part, an engine and a transmission that transmits movement from the engine to the spindle. The transmission consists of a gearbox and a gearbox. The gearbox is a set of shafts with gears attached to them. By switching gears, the spindle speed is changed, leaving the engine speed unchanged. The gearbox transmits rotation from the gearbox to the drive shaft or lead screw. The lead roller and the lead screw are designed to move the caliper on which the cutter is fixed. They allow you to coordinate the speed of the cutter with the frequency of rotation of the part. The lead roller sets the metal cutting mode, and the lead screw sets the thread pitch. The spindle, tool or fixtures are supported by the headstock and tailstock. All components of the machine are attached to the frame. Author: Pristinsky V.L.
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