CNC Technology – Page 27 – CNC Machining & Turning, Milling, Metal parts

CNC computer gong processing circuit

CNC Lathe Feed processing path refers to the path that the turning tool starts to move from the tool setting point (or the fixed origin of the machine tool) until it returns to the point and ends the processing program, including the path of cutting and the path of non cutting empty stroke such as cutting in and cutting out.

The feed route of finishing machining is basically carried out along the contour of the parts. Therefore, the key point of determining the feed route is to determine the feed route of rough machining and empty stroke.

In the CNC lathe processing, the determination of the processing route should generally follow the following principles.

① It should be able to ensure the accuracy and surface roughness of the workpiece to be processed.

② The processing route is shortest, the idle travel time is reduced, and the processing efficiency is improved.

③ The workload of numerical calculation should be simplified as much as possible.

④ For some repeated programs, subroutines should be used.

Advantages and disadvantages of CNC CNC CNC machining has the following advantages:

① The number of tooling is greatly reduced, and complex tooling is not needed to process complex parts. If we want to change the shape and size of the parts, we only need to modify the processing program of the parts, which is suitable for the development and modification of new products.

② The machining quality is stable, the machining accuracy is high, and the repetition accuracy is high, which can meet the machining requirements of aircraft.

③ In the case of multi variety and small batch production, the production efficiency is high, which can reduce the time of production preparation, machine adjustment and process inspection, and reduce the cutting time due to the use of the best cutting quantity.

④ It can process complex surface which is difficult to be processed by conventional methods, and even process some parts which cannot be observed.

Surface treatment of aluminum alloy processed by computer gong

The processing quality of machine parts, in addition to the processing accuracy, also has the processing surface quality, which is the representation of the integrity of the surface layer after processing.

With the rapid development of modern machine manufacturing industry, the requirements for machine parts are increasing day by day. Some important parts must work under the conditions of high speed, high temperature, high pressure and heavy load. Any defect in the surface layer not only directly affects the working performance of parts, but also causes accelerated wear, corrosion and failure of parts. Therefore, we must pay attention to the surface quality.

① Surface roughness surface roughness refers to the micro geometric error of machined surface. In Figure 5-8 (a), R. Represents the arithmetic mean deviation of the roughness profile. The surface roughness is usually formed by the movement path of cutting tool in machining, and the ratio of wavelength to wave height is generally less than 50.

② Surface waviness and surface transition are periodic geometric errors between macro geometric errors (△ *) and micro geometric errors (roughness). In Fig. 58 (b), a represents the height of waviness. The surface waviness is usually caused by the low frequency vibration of the process system in the process of machining, and the ratio of the surface waviness to the wave height is generally 50 ~ l ∞ 0

CNC precision mold processing technology and development

Research on key technology of design and manufacture of continuous fine blanking die for complex parts

The continuous fine blanking die for complex parts is the frontier basic technology of fine blanking technology, and it is expected to promote the whole fine blanking technology in China. Taking the synchronizer gear ring, clutch plate, longitudinal compound continuous fine blanking process and continuous fine blanking die for complex parts as the breakthrough point, the key technology of fine blanking die design and manufacturing is studied, so as to realize the rapid improvement of fine blanking die technology in China and shorten the gap with advanced countries as soon as possible.

Study on the life promotion of fine blanking die and its related key technologies

Die life is a comprehensive reflection of die material, small process and supporting product level. Taking the life of fine blanking die as the leader to carry out technical research can not only solve the problem that the life of fine blanking die is too low, but also drive the technical development of die material, fine blanking process, supporting tooling and other auxiliary products.

Research and development of fine blanking precision forging composite technology

Precision blanking and precision forging are two advanced manufacturing technologies developed in parallel. If the precision blanking parts are too thick and need precision forging, the precision forging must be too thin. They are closely related. The basic idea of developing precision forging and fine blanking compound process is to find the combination point of the two processes (such as gear parts with wheel hub and cam parts with short shaft). The precision forging in China has a long history and has a high level, so it is a good way to improve the overall level of precision blanking technology in China.

CNC computer gong milling machine

Machining center is developed from CNC milling machine. The biggest difference between CNC milling machine and machining center is that the machining center has the ability to exchange machining tools automatically. By installing different tools on the tool magazine, the machining tools on the spindle can be changed through the automatic tool changing device in one clamping, and a variety of machining functions can be realized.

CNC machining center is composed of mechanical equipment and CNC system, which is suitable for processing complex parts. CNC machining center is one of the most widely used CNC machine tools with the highest output in the world. Its comprehensive processing ability is strong, the workpiece can complete more processing content after clamping at one time, and the processing accuracy is high. For the batch workpiece with medium processing difficulty, its efficiency is 5-10 times higher than that of ordinary equipment, especially it can complete the processing that many ordinary equipment can’t complete, and it is more suitable for single piece processing with complex shape and high precision requirements or small and medium batch multi variety production. It concentrates the functions of milling, boring, drilling, tapping and cutting threads on one equipment, so that it has a variety of technological means. According to the space position of spindle machining, there are horizontal and vertical machining centers. According to the classification of process uses: boring and milling machining center, composite machining center. According to the special functions, there are single table, double table and multi table machining centers. Machining center of single axle, double axle, three axle and changeable headstock

CNC computer gong processing tool

1、 Try to install the material first and then the cutter, so as to prevent the hand from touching the cutter when installing the material. If the cutter has been installed, when loading the material, the worktable should be moved to the outside to ensure that the material will not interfere with the cutter, so as to avoid injury or breaking the cutter.

2、 When removing the tool, first observe whether the spindle stops rotating.

4、 The wrench should be put in the tool storage area after use.

5、 In the process of machining, the operator is not allowed to observe the cutting position closely to prevent chips from crashing into the eyes.

6、 Before the start of processing, check the position of the oil nozzle before opening the oil pump switch to avoid spraying oil to other positions.

7、 When pausing to observe the machining gap, the worktable must be moved away from the cutting position.

8、 After processing and before disassembling the workpiece, we must first carry out the necessary preliminary inspection of size or appearance, and only after the inspection is qualified can we disassemble the workpiece, so as to avoid the positioning problem of secondary processing and the scrapping of the workpiece after disassembly.

Classification of CNC computer gong processing

The common ones are classified by the following four methods.

Classification by process use

(1) General CNC machine tools. This kind of machine tools is the same as the traditional general machine tools. There are CNC turning, milling, boring, drilling, grinding machines, etc., and there are many kinds of each kind. For example, CNC milling machines include vertical milling, horizontal milling, tool milling, gantry milling, etc. The technological possibility of this kind of machine tool is similar to that of general machine tool, but the difference is that it can process complex shape parts.

(2) CNC machine tool center machine tool. This kind of machine tool is developed on the basis of general CNC machine tool. It is a kind of NC machine tool with automatic tool changing device (also called multi process NC machine tool or boring milling machining center, conventionally referred to as machining center) which is composed of a tool magazine (which can hold more than 10-100 tools) and automatic tool changing device on the general NC machine tool, which makes the NC machine tool further develop towards automation and high efficiency.

The difference between NC machining center machine tool and general NC machine tool is: after the workpiece is clamped once, the NC device can control the machine tool to automatically change the cutting tool, and continuously complete the milling (turning), boring, drilling, reaming, tapping and other processes on each processing surface of the workpiece. This kind of machine tools are mostly boring and milling, mainly used to process box parts. Compared with general NC machine tools, it has the following advantages

① Reduce the number of machine tools, easy to manage, for multi process parts as long as a machine can complete all processing, and can reduce the inventory of semi-finished products;

② Since the workpiece is clamped only once, the positioning error caused by multiple installation is reduced, and the machining quality can be guaranteed by the accuracy of the machine tool;

③ Process concentration reduces the auxiliary time and improves the productivity;

④ As the parts can be processed in multiple processes in one clamping on one machine tool, the number of special fixtures is greatly reduced, and the production preparation time is further shortened.

Due to the advantages of CNC machine tools, it is very popular with users, so it plays an important role in the production of CNC machine tools.

In addition, there is a kind of machining center, which is developed on the basis of lathe, with shaft parts as the main processing object. In addition to turning and boring, it can also drill, mill and tap any part of the end face and peripheral surface. This kind of machining center also has a tool magazine, which can install 4-12 tools. It is used to call this kind of machine tool turning center (TC).

(3) Multi coordinate CNC machine tool. Some complex shape parts can’t be processed with three-dimensional CNC machine tools, such as propeller, aircraft surface parts, etc. it needs more than three coordinate synthetic motion to process the required shape. Therefore, the emergence of multi coordinate CNC machine tools, which is characterized by the number of axes controlled by the CNC device is more, the structure of the machine tool is more complex, the number of coordinate axes usually depends on the processing requirements of parts. Now commonly used is 4, 5, 6 coordinate CNC machine tools. Figure 1 is the schematic diagram of five axis NC machining. At this time, the X, y, Z coordinates can be linked with the turntable rotation and tool swing at the same time to process wing and other parts.

According to the movement track classification of CNC machine tools

According to the relative motion path between the tool and the workpiece, the CNC machine tools can be divided into point control CNC machine tools, point line control CNC machine tools, contour control CNC machine tools, etc. It is described as follows:

(1) Point position control CNC machine tool. The numerical control device of this kind of machine tool can only control the moving parts of the machine tool to move accurately from one position (point) to another position (point), that is, it only controls the coordinate value of the end of the stroke, and does not carry out any cutting during the moving process. As for the moving speed and route between the two related points, it depends on the productivity. In order to have as high productivity as possible on the basis of accurate positioning, the movement between the two related points first moves to the new position quickly, and then decelerates by 1-3 levels to make it approach the positioning point slowly, so as to ensure its positioning accuracy. This kind of machine tool mainly includes CNC coordinate boring machine, CNC drilling machine, CNC punch machine and CNC measuring machine, and its corresponding CNC device is called point position control device.

(2) CNC machine tool controlled by point and line. When this kind of machine tool works, it is necessary to control not only the position (i.e. distance) between two related points, but also the moving speed and route (i.e. trajectory) between two related points. Its route is generally composed of straight lines parallel to each axis. It is different from the point control CNC machine tool in that when the moving parts of the machine tool move, it can cut along the direction of a coordinate axis (generally, it can also cut along a 45 ° oblique line, but it can not cut along a straight line with any slope), and its auxiliary functions are more than those of the point control CNC machine tool, for example, to increase the spindle speed control, cycle feed processing, cutting tool Selection and other functions. This kind of machine tool mainly has the simple numerical control lathe, the numerical control boring milling machine and the numerical control processing center and so on. The corresponding numerical control device is called point position linear control device.

(3) Contour control CNC machine tool. The control device of this kind of machine tool can continuously control two or more coordinate axes at the same time. When machining, it is necessary to control not only the starting point and the end point, but also the speed and position of each point in the whole machining process, so that the machine tool can process complex shape parts that meet the requirements of the drawing. Its auxiliary functions are also quite complete.

This kind of machine tools mainly include CNC lathes, CNC milling machines, CNC grinding machines and electrical machining machines. The corresponding numerical control device is called contour control device (or continuous control device).

According to the control mode of servo system

CNC machine tools can be divided into open-loop and closed-loop according to whether there is a detection feedback device for the controlled quantity. In the closed-loop system, according to the position of the measuring device, it can be divided into full closed-loop and half closed-loop. Based on the open-loop system, an open-loop compensation CNC system is developed.

(1) Open loop control of CNC machine tools. In the open loop control, there is no feedback device

The signal process of numerical control device is unidirectional, so there is no system stability problem. Because of the unidirectional flow of the signal, it does not check the actual position of the moving parts of the machine tool, so the machining accuracy of the machine tool is not high, and its accuracy mainly depends on the performance of the servo system. The working process is: the input data is calculated by the numerical control device, the command pulse is distributed, and the controlled worktable is moved by the servo mechanism (the servo element is usually a stepping motor).

This kind of machine tool works stably, reacts quickly, debugs conveniently and maintains simply, but its control precision is limited. It is suitable for medium and small CNC machine tools with general requirements.

(2) Closed loop control of CNC machine tools. Because the accuracy of open-loop control can not meet the requirements of precision machine tools and large-scale machine tools, it is necessary to detect its actual working position. Therefore, the detection feedback device is added to the open-loop control CNC machine tools to detect the position of the moving parts of the machine tools at any time during processing, so as to make it consistent with the position required by the CNC equipment, so as to achieve high processing accuracy.

Classified by numerical control device

CNC machine tools can be divided into hard wire (part) CNC and soft wire (part) CNC according to the CNC devices that realize the control of CNC logic function.

(1) Hard wire numerical control (called ordinary numerical control, namely NC). The input, interpolation and control functions of this kind of CNC system are realized by integrated circuits or discrete components. Generally speaking, different CNC machine tools have different control circuits, so the universality of the system is poor. Because it is all composed of hardware, the function and flexibility are also poor. This kind of system was widely used before 1970s.

(2) Flexible wire numerical control (also known as computer numerical control or microcomputer numerical control, namely CNC or MNC). This kind of system uses medium, large scale and super large scale integrated circuits to form CNC device, or microcomputer and special integrated chip. Its main NC functions are almost completely realized by software. For different NC machine tools, only different software can be programmed, while hardware can be almost universal. Therefore, it has strong flexibility and adaptability, and is also convenient for mass production. Modular software and hardware improve the quality and reliability of the system. Therefore, modern CNC machine tools all use CNC device.

Repetitive production of CNC lathe

CNC CNC lathe processing repeatability of production parts: the use of CNC grinder process preparation time occupies a higher proportion. For example Process analysis and preparation, programming, first part adjustment and trial cutting, etc., the sum of these comprehensive working hours is often tens to hundreds of times of the working hours of a single part, but these CNC lathe work contents can be saved and reused, so a part is successfully trial produced on the CNC grinder, and then put into production repeatedly, the production cycle is greatly reduced, the cost is also less, and better results can be achieved The economic benefit of the project is very good.

It is required that the CNC grinding machine can achieve high precision, high quality and high efficiency grinding under the control of computer. Compared with special grinding machine, it can save a lot of special process equipment, has strong flexible manufacturing capacity and obtains better economic benefits. Compared with ordinary grinding machine, it can eliminate many artificial interference factors in the long process of complex processing, and has good precision consistency and interchangeability of processing parts, and high processing efficiency.

The parts processed by CNC lathe should be able to give full play to the process characteristics of multi process centralized processing of CNC grinder. When CNC grinder processes parts, the situation of grinding workpiece with grinding wheel is exactly the same as that of corresponding non CNC grinder, but it can carry out some complex processing with machining accuracy requirements. For example, in the grinding range, ordinary grinder is mainly used for grinding cylindrical and circular CNC lathe In addition, it can also grind torus and complex combination surface of various forms.

The processing batch of the parts should be larger than that of the ordinary lathe to the batch CNC lathe. When the medium and small batch parts are processed by the non CNC grinder, due to various reasons, the pure cutting time only accounts for 10% – 30% of the actual working hours. When machining on the CNC grinding machine with multiple working procedures, such as grinding center, the proportion may rise to 70% – 80%, but the working hours for preparing to adjust are often much longer, so it will become uneconomic if the batch size of parts is too small.

CNC CNC lathe processing of some special parts to consider, there are some parts, although the processing batch is very small, ordinary lathe, but the shape is complex, high quality, good interchangeability, which can not meet the above requirements on non CNC grinder, can only be arranged to CNC grinder processing, such as parabola, cycloid cam and special surface mirror, etc.

CNC computer gong processing range

When the main surface of the parts with complex structure and shape and difficult to be processed by ordinary machine tools is composed of complex curves and curved surfaces, the computer gong processing needs multi coordinate linkage processing, which is difficult or even impossible to be completed on ordinary machine tools. The numerical control processing equipment is the most effective equipment for processing such parts. The common typical parts are cam, integral impeller and die.

① There are various kinds of curved disc cam, cylindrical cam, conical cam and end face cam. When machining, according to the complexity of the cam surface, three axis, four axis or five axis machining center can be selected.

② Integral impeller is commonly used in aero-engine compressor, air compressor, marine underwater propeller and so on. In addition to the characteristics of general curved surface machining, it also has many special machining difficulties, such as narrow channel, easy tool to curve with the machined surface and adjacent.

The CNC center of parts with both plane and hole system has automatic tool changing device. In one installation, it can complete the milling of the upper plane of parts and the multi-step machining of hole system, such as drilling, boring, reaming, milling and tapping. The processing part can be on one plane or on different planes. The pentahedron machining center can complete the machining of five surfaces except the clamping surface. Therefore, the parts with both plane and hole system are the preferred processing objects of computer gongs. The common parts include box parts and plate, sleeve and plate parts.

① There are plane, curved surface and hole system on the end face of parts, and some radial holes are often distributed in the radial direction. The vertical processing equipment should be selected for the disc, sleeve and plate parts whose processing parts are concentrated on a single end face, and the horizontal processing equipment should be selected for the parts whose processing parts are not on the same direction surface.

② Box parts are common box parts. Box parts generally need multi station hole system and plane processing, with high accuracy requirements, especially the shape accuracy and position accuracy. They usually need to go through milling, drilling, expanding, boring, reaming, countersinking, tapping and other steps, and need more tools. It is difficult to process on ordinary machine tools, and the number of tooling sets is large. It needs multiple clamping and alignment, and manual measurement times are many, so the accuracy is not easy Guarantee. The last installation of CNC machining center can complete 60% ～ 95% of the process content of ordinary machine tool, with good consistency of parts precision, stable quality and short production cycle.

CNC processing technology in mobile phone

First generation iPad let more people know CNC technology

The first generation iPad, released on January 28, 2010, quickly won the market. In addition to its high performance, the back shell process of CNC processing technology is also one of the highlights. Its color is still “high value” in its shape, which is liked by more consumers. It can be said that the adoption of iPad generation CNC technology will let more people know about the technology.

The first generation iPad sold high-precision and high complexity polishing CNC process back shell, which is a lot of “bonus”. The first generation iPad was initially applied to the fuselage thickness of 13.4mm, and the first generation iPad fuselage thickness of 13.4mm. CNC molding technology combined with magnesium alloy material back shell brings a strong metal texture to the product. Although from our current perspective, the thickness of the fuselage is somewhat unsatisfactory, but in terms of the background at that time, its technology has just been applied to flat products, it is not easy to achieve this.

The thickness of the first generation iPad is 13.4mm, and its technology is not so perfect. It focuses more on the appearance and interior without too much design. At the beginning of the design, the main focus of the iPad generation CNC back shell is the appearance. When holding, the body is smooth, but there is just the right grain feeling, which makes it feel better when playing with the product. In addition, the round corners around the back shell increase its portability and give people a great visual experience.

In terms of internal design, the internal performance of the first generation iPad back shell is relatively rough, the internal screw fixation method and “baffle” design are relatively abrupt, and the overall design of the back shell is poor. However, the existence of its stripe design can better provide space for components and ensure the performance of the product. The thickened design at the key position of the back shell can ensure the fixation of its function keys to a certain extent.

In addition, the internal screw fixation method and “baffle” design of the iPad with CNC process are relatively abrupt. It can be seen that the preliminary CNC process applied to the flat products is relatively rough, and there are still many areas for improvement in the internal design. However, the strict product precision and outstanding texture make the process superior to the injection molding and stamping molding processes. Of course, this is only the initial CNC process. What progress has this process made? Let’s go on.

CNC processing technology tends to be mature. Both Nokia N1 and iPad air2 adopt this technology. With the development of CNC technology, more and more tablet products are applied. The most representative ones are Apple’s latest series of tablet iPad air2 and Nokia N1 tablet computer. The back case of these two products adopts CNC technology. What are the improvements in technology and design?

Nokia N1 adopts the latest CNC process back shell, which makes the appearance more beautiful. In appearance, the products made by this process are more “slim”. The back shell gives people an overall sense of visual impact, and the appearance of the products becomes more exquisite (of course, this has a lot to do with the upgrading and improvement of the screen). The borders around the products become more rounded, which is not a rigid “frame” design, It’s more comfortable to hold it in hand. This change can be said to be a big improvement in technology.

The Nokia N1’s peripheral borders become more rounded, rather than rigid “frame” design. In addition, there are certain improvements in the details of the key position, so that the key position does not stay on the side border, but to a certain extent close to the backplane. In this way, the thickness of the body will not affect the user’s operation, which can be said to kill two birds with one stone. The realization of the design, to a certain extent, also depends on the improvement of the process.

The details of the key position have also been improved, which is easy to operate and more beautiful at the same time. The concave design of the interface has also been improved in the previous technology. There is a certain gap between the two key positions. The design makes the volume key position and the shutdown key position adjacent, which makes the side of the machine more beautiful.

The precision of CNC technology perfectly supports the design. We can see that the appearance of today’s CNC technology has been greatly improved compared with before. The round frame, the appearance is more refined, and the polishing process is more mature. The high-precision polished fuselage will have a kind of aesthetic feeling of industrial design. And these are only the improvement of appearance technology, so does the internal technology of back shell also have a qualitative improvement? Please go on to see.

The design is more reasonable while the interior design is beautiful. Compared with the exterior of the back shell, the improvement of the interior of the CNC back shell is more attractive to the author. Now the interior of the CNC back shell has become “clean” and the screw fixing place has become “small”. The position is close to the frame, which does not give people a sudden feeling of design. The overall design has been greatly improved.

How to operate computer gong processing

Generally, the workpiece processed by computer gong has complex shape, many processes, and many kinds of cutting tools. It is often necessary to complete the whole process from rough machining, semi finish machining to finish machining after one clamping. So the program is complicated. The following problems should be considered when programming.

Carefully analyze the drawings and determine the reasonable process route.
The size of the tool should be selected, and the measured actual size should be filled in the tool card.
Determine the reasonable cutting parameters. It mainly includes spindle speed, back feed, feed speed, etc.
There should be enough space for automatic tool change to avoid collision with workpiece or fixture. It is recommended to set the tool change position at the origin of the machine tool.
In order to check and debug the program, the processing contents of each step can be arranged in different subprograms, and the main program mainly completes tool change and subroutine call. This procedure is simple and clear.
Check and trial run the programmed program, and pay attention to whether there is interference among tools, fixtures or workpieces. When checking m, s and t functions, it can be carried out in the z-axis locking state.