According to the preparation method of machine tool models, machine tools are divided into 11 categories: lathes, drilling machines, boring machines, grinding machines, gear processing machines, threading machines, milling machines, planer slotting machines, broaching machines, sawing machines and other machine tools. In each type of machine tool, it is divided into several groups according to the process range, layout type and structural performance, and each group is divided into several series. Today, the editor will talk to you about the historical stories of lathes, boring machines and milling machines.
1. Lathe
A lathe is a machine tool that mainly uses a turning tool to turn a rotating workpiece. On the lathe, drills, reamers, reamers, taps, dies and knurling tools can also be used for corresponding processing. Lathes are mainly used for machining shafts, discs, sleeves and other workpieces with revolving surfaces, and are the most widely used type of machine tools in machinery manufacturing and repair shops.
1. The “bow lathe” of ancient pulleys and bow rods. As far back as ancient Egypt, people have invented the technology of turning wood with a tool while rotating it around its central axis. At first, people used two standing logs as supports to erect the wood to be turned, use the elastic force of the branches to roll the rope onto the wood, pull the rope by hand or foot to turn the wood, and hold the knife for cutting.
This ancient method has gradually evolved and developed into two or three turns of the rope on the pulley, the rope is supported on an elastic rod bent into a bow shape, and the bow is pushed and pulled back and forth to rotate the processed object for turning, which is the “bow lathe”.
2. Medieval crankshaft and flywheel drive “pedal lathe”. In the Middle Ages, someone designed a “pedal lathe” that used a pedal to rotate the crankshaft and drive the flywheel, and then drive it to the main shaft to rotate it. In the middle of the 16th century, a French designer named Besson designed a lathe for turning screws with a screw rod to make the tool slide. Unfortunately, this lathe was not popularized.
3. In the eighteenth century, bedside boxes and chucks were born. In the 18th century, someone else designed a lathe that uses a foot pedal and a connecting rod to rotate the crankshaft, which can store the rotational kinetic energy on the flywheel, and developed from directly rotating the workpiece to a rotating headstock, which is a The chuck for holding the workpiece.
4. In 1797, the Englishman Maudsley invented the epoch-making tool post lathe, which has a precision lead screw and interchangeable gears.
Maudsley was born in 1771, and at the age of 18, he was the right-hand man of the inventor Brammer. It is said that Brammer had always been a farmer, and when he was 16 years old, an accident caused a disability to his right ankle, so he had to switch to woodworking, which was not very mobile. His first invention was the flush toilet in 1778. Maudsley began to help Brahmer design hydraulic presses and other machinery until he left Brahmer at the age of 26, because Brahmer rudely rejected Moritz’s proposal to Request for wage increase above 30 shillings per week.
In the same year that Maudsley left Brammer, he built his first thread lathe, an all-metal lathe with a tool holder and tailstock capable of moving along two parallel rails. The guide surface of the guide rail is triangular, and when the spindle rotates, the lead screw is driven to move the tool holder laterally. This is the main mechanism of modern lathes, with which precision metal screws of any pitch can be turned.
Three years later, Maudsley built a more complete lathe in his own workshop, with interchangeable gears that changed the feed rate and pitch of the threads being machined. In 1817, another Englishman, Roberts, adopted a four-stage pulley and back wheel mechanism to change the spindle speed. Soon, larger lathes were introduced, which contributed to the invention of the steam engine and other machinery.
5. The birth of various special lathes In order to improve the degree of mechanization and automation, Fitch in the United States invented a turret lathe in 1845; in 1848, a wheel lathe appeared in the United States; in 1873, Spencer in the United States made a single shaft Automatic lathes, and soon he made three-axis automatic lathes; at the beginning of the 20th century there appeared lathes with gear transmissions driven by separate motors. Due to the invention of high-speed tool steel and the application of electric motors, lathes have been continuously improved and finally reached the modern level of high speed and high precision.
After the First World War, due to the needs of the arms, automobile and other machinery industries, various high-efficiency automatic lathes and specialized lathes developed rapidly. In order to improve the productivity of small batches of workpieces, in the late 1940s, lathes with hydraulic profiling devices were promoted, and at the same time, multi-tool lathes were also developed. In the mid-1950s, program-controlled lathes with punch cards, latch plates and dials were developed. CNC technology began to be used in lathes in the 1960s and developed rapidly after the 1970s.
6. Lathes are divided into various types according to their uses and functions.
The ordinary lathe has a wide range of processing objects, and the adjustment range of the spindle speed and feed is large, and it can process the inner and outer surfaces, end faces and internal and external threads of the workpiece. This type of lathe is mainly operated manually by workers, with low production efficiency, and is suitable for single-piece, small-batch production and repair workshops.
Turret lathes and rotary lathes have turret tool rests or rotary tool rests that can hold multiple tools, and workers can use different tools to complete various processes in one clamping of the workpiece, which is suitable for mass production.
The automatic lathe can automatically complete the multi-process processing of small and medium-sized workpieces according to a certain program, can automatically load and unload materials, and process a batch of the same workpieces repeatedly, which is suitable for mass production.
Multi-tool semi-automatic lathes are divided into single-axis, multi-axis, horizontal and vertical. The layout of the single-axis horizontal type is similar to that of an ordinary lathe, but the two sets of tool rests are installed on the front and back or up and down of the main shaft, respectively, and are used to process discs, rings and shaft workpieces, and their productivity is 3 to 5 times higher than that of ordinary lathes.
The profiling lathe can automatically complete the machining cycle of the workpiece by imitating the shape and size of the template or the sample. It is suitable for small batch and batch production of workpieces with complex shapes, and the productivity is 10 to 15 times higher than that of ordinary lathes. There are multi-tool holder, multi-axis, chuck type, vertical type and other types.
The spindle of the vertical lathe is perpendicular to the horizontal plane, the workpiece is clamped on the horizontal rotary table, and the tool rest moves on the beam or column. It is suitable for processing large, heavy workpieces that are difficult to install on ordinary lathes. Generally, they are divided into two categories: single-column and double-column.
While the shovel tooth lathe is turning, the tool holder periodically reciprocates in the radial direction, which is used for forming tooth surfaces of forklift milling cutters, hob cutters, etc. Usually with a relief grinding attachment, a small grinding wheel driven by a separate electric motor relieves the tooth surface.
Specialized lathes are lathes used to machine specific surfaces of certain types of workpieces, such as crankshaft lathes, camshaft lathes, wheel lathes, axle lathes, roll lathes, and ingot lathes.
The combined lathe is mainly used for turning processing, but after adding some special parts and accessories, it can also perform boring, milling, drilling, inserting, grinding and other processing. It has the characteristics of “one machine with multiple functions” and is suitable for engineering vehicles, ships or mobile Repair work at the repair station.
2. Boring machine
Although the workshop industry is relatively backward, it has trained and produced many craftsmen. Although they are not experts in making machines, they can make all kinds of hand tools, such as knives, saws, Needles, drills, cones, grinders, shafts, sleeves, gears, bed frames, etc., in fact, machines are assembled from these parts.
1. The earliest designer of the boring machine – Da Vinci boring machine is known as the “Mother of Machinery”. Speaking of boring machines, we have to talk about Leonardo da Vinci first. This legendary figure may have been the designer of the earliest boring machines for metalworking. The boring machine he designed is powered by hydraulic or foot pedal, the boring tool rotates close to the workpiece, and the workpiece is fixed on a mobile table driven by a crane. In 1540, another painter painted a picture of “Pyrotechnics” with the same drawing of a boring machine, which was used for finishing hollow castings at that time.
2. The first boring machine born for the processing of cannon barrels (Wilkinson, 1775). In the 17th century, due to military needs, the development of cannon manufacturing was very rapid, and how to manufacture the barrel of the cannon became a major problem that people urgently needed to solve.
The world’s first true boring machine was invented by Wilkinson in 1775. In fact, Wilkinson’s boring machine is, to be precise, a drilling machine capable of precisely machining cannons, a hollow cylindrical boring bar mounted on bearings at both ends.
Born in America in 1728, Wilkinson moved to Staffordshire at the age of 20 to build Bilston’s first iron furnace. For this reason, Wilkinson was called the “Master Blacksmith of Staffordshire”. In 1775, at the age of 47, Wilkinson worked hard at his father’s factory to create this new machine that could drill cannon barrels with rare precision. Interestingly, after Wilkinson died in 1808, he was buried in a cast iron coffin of his own design.
3. The boring machine made an important contribution to Watt’s steam engine. The first wave of the Industrial Revolution would not have been possible without the steam engine. For the development and application of the steam engine itself, in addition to the necessary social opportunities, some technical prerequisites cannot be ignored, because manufacturing the parts of the steam engine is not as easy as cutting wood by a carpenter. It is necessary to make some special metal parts shape, and the processing accuracy requirements are high, which cannot be achieved without the corresponding technical equipment. For example, in the manufacture of the cylinder and piston of a steam engine, the accuracy of the outer diameter required in the manufacturing process of the piston can be cut from the outside while measuring the size, but to meet the accuracy requirements of the inner diameter of the cylinder, it is not easy to use general processing methods. .
Smithton was the finest mechanic of the eighteenth century. Smithton designed as many as 43 pieces of water and windmill equipment. When it came to making the steam engine, the most difficult thing for Smithon was machining the cylinder. It is quite difficult to machine a large cylinder inner circle into a circle. To this end, Smithton made a special machine tool for cutting cylinder inner circles at the Cullen Iron Works. This kind of boring machine, which is powered by a waterwheel, is equipped with a tool at the front end of its long axis, and the tool can be rotated in the cylinder to process its inner circle. Since the tool is installed at the front end of the long shaft, there will be problems such as shaft deflection, so it is very difficult to machine a truly circular cylinder. To this end, Smithton had to change the position of the cylinder several times for machining.
The boring machine invented by Wilkinson in 1774 played a big role in this problem. This kind of boring machine uses the water wheel to rotate the material cylinder and push it toward the fixed tool in the center. Due to the relative movement between the tool and the material, the material is bored into a cylindrical hole with high precision. At the time, a boring machine was used to make a cylinder with a diameter of 72 inches within the thickness of a sixpence coin. Measured with modern technology, this is a big error, but under the conditions at the time, it was not easy to reach this level.
However, Wilkinson’s invention was not patented, and people copied it and installed it. In 1802, Watt also wrote about Wilkinson’s invention, which he copied at his Soho ironworks. Later, when Watt made the cylinders and pistons of the steam engine, he also used this amazing machine of Wilkinson. It turned out that for the piston, it is possible to measure the size while cutting it, but it is not so simple for the cylinder, and a boring machine must be used. At that time, Watt used the water wheel to rotate the metal cylinder, so that the fixed center tool was pushed forward to cut the inside of the cylinder. As a result, the error of the cylinder with a diameter of 75 inches was less than the thickness of a coin. It’s very advanced.
4. The birth of the table-lifting boring machine (Hutton, 1885) In the following decades, many improvements have been made to Wilkinson’s boring machine. In 1885, Hutton in the United Kingdom manufactured the table lifting boring machine, which has become the prototype of the modern boring machine.
3. Milling machine
In the 19th century, the British invented the boring machine and planer for the needs of the industrial revolution such as the steam engine, while the Americans concentrated on the invention of the milling machine in order to produce a large number of weapons. A milling machine is a machine with milling cutters of various shapes, which can cut workpieces with special shapes, such as helical grooves, gear shapes, etc.
As early as 1664, the British scientist Hook created a machine for cutting by relying on rotating circular cutters. This can be regarded as the original milling machine, but at that time society did not respond enthusiastically. In the 1840s, Pratt designed the so-called Lincoln milling machine. Of course, the one who really established the status of milling machines in machine manufacturing was the American Whitney.
1. The first ordinary milling machine (Whitney, 1818) In 1818, Whitney made the world’s first ordinary milling machine, but the patent for the milling machine was British Bodmer (with a tool feeding device). The inventor of the gantry planer) “obtained” in 1839. Due to the high cost of milling machines, there were not many people who were interested at that time.
2. The first universal milling machine (Brown, 1862) After a period of silence, the milling machine became active again in the United States. In contrast, Whitney and Pratt can only be said to have laid the foundation for the invention and application of the milling machine, and the credit for truly inventing a milling machine that can be applied to various operations in the factory should be attributed to American engineer Joseph Brown.
In 1862, Brown in the United States produced the world’s first universal milling machine, which is an epoch-making innovation in the provision of universal indexing discs and comprehensive milling cutters. The table of the universal milling machine can rotate a certain angle in the horizontal direction, and has accessories such as an end milling head. His “universal milling machine” was a great success when it was exhibited at the Paris Exposition in 1867. At the same time, Brown also designed a shaped milling cutter that would not deform after grinding, and then manufactured a grinding machine for grinding the milling cutter, bringing the milling machine to the current level.
Post time: Jun-02-2022