As early as in ancient Egypt, people have invented the technology of turning wood with tools when it rotates around its central axis. At first, people used two vertical trees as support to stand up the wood to be turned, used the elasticity of branches to roll the rope onto the wood, pulled the rope with their hands or pedals to turn the wood, and cut it with a knife.
This ancient method has gradually evolved into a "bow car", in which the rope is wound around a pulley for two or three times, and the rope is supported on an elastic rod bent into an arch to push and pull the bow back and forth to make the processed object rotate.
"Bicycle bed" driven by crankshaft and flywheel in the Middle Ages
In the middle ages, someone designed a kind of "bicycle bed", which used pedals to drive the crankshaft to rotate, drive the flywheel, and then transmitted it to the spindle to make it rotate. /kloc-In the middle of the 6th century, a French designer named Besson designed a lathe, which could screw screws with a threaded rod. Unfortunately, this lathe is not popular.
/kloc-in the 0/8th century, headstock and chuck were born.
/kloc-in the 8th century, a crankshaft with pedals and connecting rods was designed, which can store the rotational kinetic energy of lathe on flywheel, and develop from directly rotating workpiece to rotating headstock, which is a chuck for clamping workpiece.
An Englishman Mozley invented the tool rest lathe (1797).
In the story of inventing the lathe, the most striking thing is an Englishman named Maudslay, because he invented the epoch-making tool rest lathe in 1797, which has precise screw and interchangeable gears.
In order to improve the degree of mechanization and automation, various special lathes were born. 1845, Fitch of the United States invented the turret lathe. 1848, turning lathes appeared in America. 1873, Spencer of the United States made a single-axis automatic lathe, and soon he made a three-axis automatic lathe. At the beginning of the 20th century, a lathe with gearbox driven by a single motor appeared. Due to the invention of high-speed tool steel and the application of motor, the lathe has 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 machinery industry such as arms and automobiles, various high-efficiency automatic lathes and special lathes developed rapidly. In order to improve the productivity of small batch of workpieces, at the end of1940s, lathes with hydraulic copying devices were popularized and multi-tool lathes were developed. 1in the mid-1950s, a program-controlled lathe with punched cards, latch plates and dials was developed. Numerical control technology was applied to lathes in1960s, and developed rapidly after1970s.
Classification of lathes According to their uses and functions, lathes are divided into many types.
Ordinary lathe has a wide range of machining objects, a wide range of spindle speed and feed adjustment, and can process the internal and external surfaces, end faces and internal and external threads of workpieces. This kind of lathe is mainly operated by workers, which has low production efficiency and is suitable for single-piece and small-batch production and repair workshops.
Turret lathes and rotary lathes have turret tool holders or turret tool holders that can hold multiple tools. Workers can use different tools to complete various processes in one clamping process, which is suitable for mass production.
Automatic lathe can automatically complete the multi-process processing of small and medium-sized workpieces according to certain procedures, and can automatically load and unload and repeatedly process a batch of the same workpieces, which is suitable for mass production.
Multi-tool semi-automatic lathe can be divided into single axis, multi-axis, horizontal and vertical. The layout of single-axis horizontal lathe is similar to that of ordinary lathe, but two groups of tool holders are installed at the front and back of the spindle or up and down, respectively, to process disc, ring and shaft workpieces, and its productivity is 3 ~ 5 times higher than that of ordinary lathe.
The copying lathe automatically completes the machining cycle of the workpiece by imitating the shape and size of the template or sample. It is suitable for small batch and batch production of workpieces with complex shapes, and the productivity is 10 ~ 15 times higher than that of ordinary lathes. There are many types, such as multi-tool rest, multi-axis, chuck type and vertical type.
The spindle of vertical lathe is vertical 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 machining large and heavy workpieces that are difficult to install on ordinary lathes. Generally, it can be divided into single column and double column.
The relief lathe periodically makes radial reciprocating motion during turning, which is used to shape the tooth surfaces of forklifts, milling cutters, hobs, etc. Usually, shovel accessories, small grinding wheels driven by independent motors are used to shovel tooth surfaces.
Special lathes are lathes used to process the specific surface of a certain type of workpiece, such as crankshaft lathes, camshaft lathes, wheel lathes, axle lathes, roller lathes and spindle lathes.
Combined lathe is mainly used for turning, but with some special parts and accessories, it can also be used for boring, milling, drilling, inserting and grinding. It has the characteristics of "one machine with multiple functions" and is suitable for repair work on engineering vehicles, ships or mobile repair stations. Although the workshop handicraft industry is relatively backward, it has trained and brought up many technicians. 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, bedsteads and so on. In fact, the machine is assembled from these parts.
The earliest boring machine designer-Da Vinci. Boring machine is called "the mother of machinery". When it comes to boring machines, we have to talk about Leonardo da Vinci first. This legendary figure may be the designer of the earliest boring machine used for metal processing. The boring machine he designed is powered by hydraulic power or pedal, the boring cutter rotates near the workpiece, and the workpiece is fixed on the mobile platform driven by the crane. 1540, another painter drew a picture of fireworks, and also had the same boring machine drawing. At that time, the boring machine was specially used for finishing hollow castings.
The first boring machine for processing gun barrel (Wilkinson, 1775). /kloc-in the 0/7th century, due to military needs, the artillery manufacturing industry developed very rapidly, and how to manufacture gun barrels became a major problem that people urgently needed to solve. The first real boring machine in the world was invented by Wilkinson in 1775. In fact, Wilkinson's boring machine is a kind of drilling machine that can accurately process cannons. It is a hollow cylindrical boring bar with two ends mounted on bearings.
Wilkinson 1728 was born in America. At the age of 20, he moved to Staffordshire and built the first ironmaking blast furnace in Bilston. Therefore, Wilkinson is called "the blacksmith master in Staffordshire". 1775, 47-year-old Wilkinson made continuous efforts in his father's factory, and finally made this new machine which can drill the gun barrel with rare accuracy. Interestingly, Wilkinson died in 1808 and was buried in a cast iron coffin designed by himself.
Boring machine made an important contribution to Watt's steam engine. Without the steam engine, the first wave of industrial revolution would not have occurred at that time. The development and application of the steam engine itself, in addition to the necessary social opportunities, some technical prerequisites can not be ignored, because the manufacturing of steam engine parts is far less easy than carpenters cutting wood, it is impossible to make metal into some special shapes, and the processing accuracy is high, and there is no corresponding technical equipment. For example, when manufacturing the cylinder and piston of a steam engine, the accuracy of the outer diameter required in the piston manufacturing process can be cut from the outside while measuring the size, but it is not easy to meet the accuracy requirement of the inner diameter of the cylinder with general processing methods.
Smith is the best mechanic in18th century. Smithton designed as many as 43 waterwheels and windmills. When making a steam engine, the most difficult thing for Smithton is to process the cylinder. It is quite difficult to process the inner circle of a large cylinder into a circle. To this end, Smithton made a special machine tool for cutting the inner circle of the cylinder in Cullen Iron Works. This boring machine driven by waterwheel is equipped with a cutter at the front end of its long shaft, and the cutter can rotate in the cylinder body, so that its inner circle can be machined. Because the cutter is installed at the front end of the long shaft, there will be problems such as shaft deviation, so it is very difficult to process the real cylinder. To this end, Smithton had to change the position of the cylinder several times for processing.
For this problem, the boring machine invented by Wilkinson in 1774 played a great role. This kind of boring machine uses a water wheel to make the cylinder rotate and aim it at the fixed center cutter to move forward. Due to the relative motion between the cutter and the material, the material is drilled into the cylindrical hole with high precision. At that time, a boring machine was used to make a cylinder with a diameter of 72 inches, and the error was not more than the thickness of a sixpence coin. Measured by modern technology, this is a big error, but under the conditions at that time, it was not easy to reach this level.
But Wilkinson's invention did not apply for patent protection, and people copied it and installed it. In 1802, Watt also talked about Wilkinson's invention in his book and copied it in his Su He Iron Works. Later, when Watt made the cylinder and piston of the steam engine, he also applied Wilkinson, a magical machine. Originally, for the piston, it was possible to measure the dimension while cutting the outside, but for the cylinder, it was not so simple, and a boring machine was needed. At that time, Watt used a water truck to rotate the metal cylinder, so that the tool with fixed center moved forward and cut the inside of the cylinder. As a result, the error of a cylinder with a diameter of 75 inches is less than the thickness of a coin, which is very advanced in the right place.
Desktop lifting boring machine was born (Hutton, 1885). In the following decades, Wilkinson's boring machine was improved many times. 1885, Hutton, England, made a bench-type lifting boring machine, which became the prototype of modern boring machine. Milling machine refers to a machine tool that mainly uses milling cutter to process various surfaces on workpieces. Generally, the rotary motion of the milling cutter is the main motion, and the motion of the workpiece (and) the milling cutter is the feed motion. Can process planes and grooves, as well as various curved surfaces and gears. Milling machine is a machine tool for milling workpieces with milling cutter. Milling machines can not only mill planes, grooves, gear teeth, threads and spline shafts, but also process more complex contours, with higher efficiency than planers, and are widely used in machinery manufacturing and repair departments.
/kloc-in the 0/9th century, the British invented boring machines and planers for the needs of the industrial revolution such as steam engines, while the Americans devoted themselves to the invention of milling machines for mass production of weapons. Milling machine is a machine with milling cutters with different shapes, which can cut workpieces with special shapes, such as spiral grooves and tooth profiles.
As early as 1664, the British scientist Hooke made a machine that cut by rotating a circular cutter, which can be regarded as an original milling machine, but there was no enthusiastic response from the society at that time. 1In the 1940s, Pratt designed the so-called Lincoln milling machine. Of course, it is American Whitney who really established the position of milling machine in machinery manufacturing.
The first ordinary milling machine (Whitney, 18 18). 18 18, Whitney made the world's first ordinary milling machine, but the patent of milling machine was "won" by Englishman Bodmer (inventor of gantry planer with cutter feeding device) in 1839. Due to the high cost of milling machines, there were not many buyers at that time.
The first universal milling machine (Brown, 1862). After a period of silence, milling machines are active again in America. In contrast, Whitney and Pratt can only say that they have done a foundation work for the invention and application of milling machines. The achievement of truly inventing the milling machine that can be applied to various operations in factories should belong to Joseph Brown, an American engineer.
1862, Brown made the earliest universal milling machine in the world, which was an epoch-making initiative in providing universal indexing discs and comprehensive milling cutters. The worktable of universal milling machine can rotate at a certain angle in the horizontal direction, and it has accessories such as vertical milling head. The "universal milling machine" designed by him was a great success when it was exhibited at 1867 Paris Expo. At the same time, Brown also designed a shaped milling cutter that will not deform after grinding, and then made a grinder for grinding the milling cutter, which made the milling machine reach the present level. In the process of invention, many things are often complementary and interlocking: in order to manufacture steam engines, boring machines are needed; After the invention of the steam engine, it is also called the gantry planer technically. It can be said that it was the invention of the steam engine that led to the design and development of "working machine" from boring machine, lathe to gantry planer. In fact, the planer is a kind of "planer" for planing metal.
Gantry planer for machining large plane (1839). Since the beginning of19th century, many technicians began to study the plane machining of steam engine valve seats, including Richard Robert, Richard Pratt, james fox and Joseph Clement. From 18 14, it took them 25 years to independently manufacture the planer. This planer fixes the processed object on the reciprocating platform, and the planer cuts one side of the processed object. However, this planer has no feed device and is in the process of transforming from "tool" to "machine". 1839, an Englishman named Bommer finally designed a planer with a cutter feeding device.
A forming machine for machining small planes. Another Englishman, nasmyth, invented and manufactured a planer for processing small planes from 183 1 in 40 years. It can fix the object to be processed on the machine bed, and the cutter moves back and forth.
Since then, due to the improvement of tools and the appearance of motors, the gantry planer has developed in the direction of high-speed cutting and high precision on the one hand, and in the direction of large-scale on the other. Grinding is an ancient technology that human beings have known since ancient times. This technology was used to grind stone tools in the Paleolithic Age. Later, with the use of metal appliances, the development of grinding technology was promoted. However, it is still a modern thing to design a veritable grinder. Even in the early19th century, people still grind natural grindstones by rotating them and bringing them into contact with the processed objects.
The first grinding machine (1864). 1864, the United States made the world's first grinding machine, which is a device to install grinding wheel on the carriage of lathe to make it have automatic speed change. 12 years later, Brown of the United States invented the universal grinder close to the modern grinder.
Man-made grinding disc-the birth of grinding wheel (1892). The demand for artificial grindstones has also increased. How to develop a grindstone that is more wear-resistant than natural grindstone? 1892, American Acheson successfully trial-produced silicon carbide made of coke and sand, which is an artificial grindstone now called C abrasive. Two years later, the abrasive A with alumina as the main component was successfully trial-produced, which made the grinder more widely used.
Later, due to the further improvement of bearings and guide rails, the accuracy of grinders became higher and higher, and they developed in the direction of specialization. Internal grinder, surface grinder, roller grinder, gear grinder and universal grinder appeared. Ancient drilling machine-"bow pulley" Drilling technology has a long history. Archaeologists now find that in 4000 BC, humans invented a device for digging holes. The ancients put a beam on two pillars, then hung a rotatable awl from the beam, and then wrapped the awl with bowstring to drive it to rotate, so that holes could be punched in wood and stone. Soon, people also designed a punching tool called "pulley", which also uses elastic bowstring to make the awl rotate.
The first drilling rig (whitworth, 1862). In about 1850, the German Martini first made a twist drill for punching metal. 1862 At the international exposition held in London, England, whitworth, an Englishman, exhibited the electric drilling machine with cast iron frame, which became the prototype of modern drilling machine.
Later, various drilling machines appeared one after another, including radial drilling machines, drilling machines with automatic feed mechanisms, and multi-spindle drilling machines that can drill multiple holes at the same time. Due to the improvement of tool materials and drill bits and the use of electric motors, a large-scale high-performance drilling rig was finally manufactured. It is the abbreviation of numerical control machine tool, and it is an automatic machine tool with program control system. The control system can logically process and decode the program with control codes or other symbolic instructions, so that the control unit of machine tool action and machining parts, the operation and monitoring of CNC machine tools are completed in this CNC unit, which is the brain of CNC machine tools.
High machining precision and stable machining quality;
Multi-coordinate linkage can be carried out to process parts with complex shapes;
When the machined parts change, it is generally only necessary to change the numerical control program, which can save the production preparation time;
The machine tool itself has high precision and rigidity, and can choose favorable processing dosage and high productivity (generally 3~5 times that of ordinary machine tools);
The machine tool has a high degree of automation, which can reduce labor intensity;
The quality of operators is required to be higher, and the technical requirements of maintenance personnel are higher.
CNC machine tools generally consist of the following parts:
The main machine is the main body of CNC machine tools, including machine bed, column, spindle, feed mechanism and other mechanical parts. It is a mechanical component used to complete various cutting processes.
Numerical control device is the core of numerical control machine tool, including hardware (printed circuit board, CRT display, key box, paper tape reader, etc. ) and corresponding software are used to input digital parts programs, and complete the storage, data conversion, interpolation operation and various control functions of input information.
The driving device is the driving part of the executive mechanism of CNC machine tools, including spindle driving unit, feed unit, spindle motor and feed motor. Under the control of numerical control device, the spindle and feed drive are realized by electric or electro-hydraulic servo system. When multiple feeds are linked, positioning, straight line, plane curve and space curve can be processed.
Auxiliary equipment refers to some supporting components necessary for the operation of CNC machine tools, such as cooling, chip removal, lubrication, lighting, monitoring and so on. It includes hydraulic and pneumatic devices, a chip removal device, an exchange workbench, a numerical control turntable and a numerical control indexing head, as well as a cutter and a monitoring detection device.
Programming and other auxiliary equipment can be used to program and store parts outside the machine.
Description of machining process of NC machine tool
CAD: Computer aided design, that is, computer aided design. 2D or 3D workpiece or stereo design
CAM: computer-aided manufacturing, that is, computer-aided manufacturing. Generating g code with CAM software
CNC: CNC machine tool controller, reading G code to start machining.
Description of machining program of NC machine tool
CNC programs can be divided into main programs and subroutines (subroutines). Any part of repeated processing can be written by subroutines to simplify the design of the main program.
Characters (digital data) → text → single section → processing program.
As long as Notepad is opened in Windows operating system, the NC code can be edited, and the NC program written can simulate the correctness of tool path with simulation software.
Description of basic functions of CNC machine tools
The so-called function instruction is composed of address code (English letters) and two numbers, and has certain actions or functions, which can be divided into seven categories, namely, G function (preparation function), M function (auxiliary function), T function (cutter function), S function (spindle speed function), F function (feed speed function), N function (single-segment numbering function) and H/D function.
Description of reference point of NC machine tool
Usually, when programming CNC machine tools, at least one reference coordinate point must be selected to calculate the coordinate values of each point on the working drawing. These reference points are called zero or origin, and commonly used reference points are mechanical origin, regression reference point, working origin and program origin.
Machine reference point: machine reference point or mechanical origin, which is a fixed mechanical reference point.
Reference point: There is a reference point on each axis of the machine tool, and the positions of these reference points are accurately set in advance by the limit switch of the travel monitoring device as the return points of the workbench and the spindle.
Working reference point: Working reference point or working origin, which is the origin of working coordinate system, is floating, and is set by programmers according to their needs, usually at any position on the workbench (at work).
Program reference point: when writing a program, you must choose the program reference point or the program origin, that is, the reference point of the coordinate values of all turning points in the work, so the programmer must choose a convenient point to facilitate the programming.
Steel telescopic guide is made of high-quality 2-3mm thick steel plate by cold pressing, and can also be made of stainless steel as required. Special surface polishing will add value to it. We can provide corresponding guide rail protection types (horizontal, vertical, inclined and horizontal) for all machine tools. High-efficiency crankshaft special machine tool also has its processing limitations. Only by reasonably applying suitable machining tools can the efficiency and specificity of crankshaft machining tools be brought into play, thus improving the machining efficiency of the working procedure.
1. When the crankshaft journal is undercut, the CNC internal milling machine cannot process it; If the crankshaft journal has an undercut in the axial direction, neither the NC high-speed external milling machine nor the NC internal milling machine can process it, but the NC lathe-lathe can process it conveniently.
2. When the side of the balance weight needs to be machined, the CNC internal milling machine is the first choice, because the external circle of the internal milling disc is positioned and has good rigidity, which is especially suitable for machining large forged steel crankshafts; At this time, it is not suitable to use CNC lathe-broaching machine tool, because when the balance weight side of crankshaft needs machining, CNC lathe-broaching machine tool is used for machining, and the balance weight side cuts intermittently, so the crankshaft speed is very high. Under this working condition, the phenomenon of knife collapse is more serious.
3. In principle, when the crankshaft journal has no undercut and the side of the balance weight does not need to be machined, several machine tools can be used for machining. When machining car crankshaft, the main journal should be broached by CNC lathe, and the connecting rod journal should be milled by CNC high-speed external milling machine. When machining large forged steel crankshaft, it is more reasonable to use CNC internal milling machine tool for main journal and connecting rod journal.
Crankshaft can be divided into large forged steel crankshaft and light automobile crankshaft. Generally, the journal of forged steel crankshaft has no undercut, and the side faces need to be machined, so the allowance is large. Generally, the crankshaft journals of automobiles have undercut grooves, and the side faces do not need to be machined. Therefore, it can be concluded that it is a reasonable and efficient choice to process forged steel crankshaft with CNC internal milling machine tool, main journal of car crankshaft with CNC lathe-lathe machine tool and connecting rod journal with CNC high-speed external milling machine tool. Forging press is equipment and machinery used for cold working of metals. It just changed the shape of the metal. Forging machine tools include plate bending machine, shearing machine, punching machine, press, hydraulic press, bending machine, etc.
There are many kinds of machine tool accessories, including flexible organ guard (leather tiger), blades, steel stainless steel guide guard, telescopic spiral guard, roller shutter guard, protective skirt curtain, dust-proof folding cloth, steel drag chain, engineering plastic drag chain, machine tool working lamp, machine mattress, JR-2 rectangular metal hose, DGT catheter protective sleeve, adjustable plastic cooling pipe, vacuum tube, ventilation tube, explosion-proof tube and travel trough plate.