Category Archive CNC Technology

The technology content of drilling, milling and tapping central machine will be greatly improved in a short time. At that time, more businesses will recognize the drilling, milling and tapping central machine, and more enterprises will use the drilling, milling and tapping central machine. Its future development prospects will be broader.

Drilling, milling and tapping center machine is a kind of machining equipment which has different specifications of through-hole or blind hole in the shell, equipment end face, nut and other tools of CNC machine tool, and the thread, screw or thread are machined on the inner side of parts. Let’s first understand the characteristics of drilling and milling center machine.

The drilling, milling and tapping center machine is very simple when adjusting the model. The automatic reverse device can freely adjust the working stroke of the drilling and milling tapping center machine. The processing workpieces with shallow holes and holes can be easily adjusted. In the double installation device, the screw tap can be prevented from damage, and the spindle can be back and forth and up and down. The double safety clutch is specially designed for the advance and retreat of the cutter. The spindle can stop automatically and the tool will not be damaged by the reversing tool withdrawal. The gear of drilling and milling center machine matches with the pitch between the spindle and the spindle to promote complete matching, vertical stability, accuracy, and high precision. When the screw taps, it can move forward and backward without output. At the same time, it can be configured with multi axis synchronous processing, and the production efficiency will be greatly improved

It can also reduce and save labor: drilling, milling and tapping center machine combines tapping and stamping of parts into a process, which can be fully automated, thus saving labor costs. It can also reduce adverse effects. Accurate positioning of drilling and milling center machine can reduce the damage probability of taps. At the same time, it can also reduce the accurate positioning of drilling and milling center machine, and provide the probability of waste products caused by errors. CNC machining center drilling milling tapping center machine can use the existing factory, such as ordinary drilling machine, at the same time to save time, labor and money.

With the continuous improvement of the degree of production automation, the application of drilling, milling and tapping center machine is expanding rapidly, the varieties and specifications of products continue to increase, the performance and quality are constantly improving, and the output value of market sales is also growing steadily. So what are the common problems in the use of drilling milling tapping center machine? How to solve this problem? Well, today’s editor will help you solve these problems.

1. Breaking of drill tap

Solutions: when the tap of drilling and milling center machine is broken, the diameter of thread bottom hole should be correctly selected; the drilling depth of grinding edge angle or spiral groove tap should reach the specified standard; the cutting speed should be appropriately reduced and selected according to the standard; when tapping, correct the tap and bottom hole to ensure its coaxiality meet the requirements, and select floating tapping chuck; increase the tap The front angle, shorten the length of the cutting cone; ensure that the hardness of the workpiece meets the requirements, select the safety collet; the anti County tap wear should be replaced in time.

1. Tap tooth breakage

Solution: tap tooth chipping, properly reduce the tap front angle; appropriately increase the length of the cutting tap; reduce the hardness and replace the tap in time. High speed computer gong machining taps wear too fast, properly reduce the cutting speed; reduce the tap front angle, lengthen the length of the cutting tap; select a good lubricating cutting fluid; carry out appropriate heat treatment on the workpiece to be processed; and correctly grind the tap.

1. Excessive pitch diameter of thread

Solutions: if the pitch diameter of the thread is too large, select the tap pitch diameter with reasonable accuracy level; select the appropriate cutting fluid and reduce the cutting speed appropriately; correct the coaxiality of the tap and the bottom hole of the thread when drilling and milling the tapping center machine, and use the floating chuck; appropriately reduce the front angle and the back angle of the cutting tap; remove the burr generated by the grinding tap and appropriately increase the length of the cutting tap.

1. Too small pitch diameter of thread

Solutions: if the thread pitch diameter is too small, select the tap pitch diameter with appropriate accuracy level; properly increase the tap front angle and cutting angle; replace the tap with excessive wear; select the cutting fluid with good lubrication for drilling, milling and tapping center machine.

1. The surface roughness of thread is too large

Solution: if the surface roughness value of thread is too large, properly increase the front angle of the tap to reduce the cutting angle; conduct heat treatment to properly improve the hardness of the workpiece to ensure that there is a low surface roughness value on the front cutter surface of the tap; select the cutting fluid with good lubrication; appropriately reduce the cutting speed; replace the worn tap for the drilling and milling center machine.

How does drilling, milling and tapping center machine base on the market? This is the drilling and milling tapping center machine industry has been thinking about the problem, we will analyze this problem.

Drilling, milling and tapping center machine is a kind of metal cutting equipment, of course, it can also drill holes, but from this name, we can see that it is also very aggressive. Well, after a simple understanding of the drilling and milling center machine, the next step is to analyze the current situation of the overall market. In recent years, it is obvious to all that whether it is the mobile phone industry, the communication industry, and of course, the tablet computer industry has grown and matured step by step from the rise to the continuous updating to please consumers. In philosophy, it is said that we are related. The rise of these industries also led to other industries, drilling, milling and tapping center machine market is also rising.

How to make drilling milling tapping center machine really based on the market. The answer is: as long as those who want to understand the needs of customers and want to be truly customers

In fact, computer gong is a CNC milling machine. In Guangzhou, Zhejiang and Shanghai, a person named “CNC machining center” is an automatic machine tool with program control system. (CNC machine tool) is a short name for computer numerical control, and it is an automatic machine tool controlled by program. The control system can logically process the program with control code or other symbol instructions, decode it by computer, so that the machine tool can act and process parts. The rough blank is processed into semi-finished finished parts by cutting tools.

CNC machining is the machining of CNC machining, which is made by means of CNC tools. CNC index control machine tool is programmed and controlled by NC machining language, usually G code. NC machining G code language tells the NC machine tool which Cartesian position coordinates to use, and control the feed speed and spindle speed of the tool, as well as tool converter, coolant and other functions. NC machining has a great advantage over manual machining. High speed computer gong processing, such as parts produced by NC machining, is very accurate and repeatable; NC machining can produce parts with complex shape which cannot be completed by manual machining. CNC machining technology has been widely spread, most machining workshops have the ability of NC machining. The most common NC machining methods in typical machining workshops are NC milling, CNC car and CNC EDM wire cutting (EDM). The tool for NC milling is called CNC milling machine or CNC machining center. The lathe for NC turning is called the CNC lathe center. The G code of NC machining can be programmed manually, but the machining workshop usually uses cam (Computer Aided Manufacturing) software to read CAD (CAD) files automatically and generate G code program to control the NC machine tool. The leading CNC machine brands are Hass, DMG (Deckel MAHO gildemester), Mazak, Mori Seiki, fadal and wasino.

2、 The route of computer gong processing:

The feed machining route of CNC lathe refers to the path that the tool moves from the point of alignment (or fixed origin of machine tool) until it returns to the point and ends the machining procedure, including the path of cutting and the path of cutting tool cutting and cutting out.

The feed route of finishing is basically carried out in the order of the outline of parts. Therefore, the key to determine the feed route is to determine the feed route of rough machining and empty stroke.

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

① The accuracy and surface roughness of the workpiece to be processed shall be guaranteed.

② The shortest processing route, reducing the time of empty travel and improving the processing efficiency.

③ The work of numerical calculation and the processing procedure are simplified as much as possible.

④ For some reuse programs, subroutines should be used.

Besides the characteristics of ordinary milling machine, NC milling has the following characteristics:

1. The parts processing is adaptable and flexible, and can process parts with complex outline or difficult to control size, such as mold parts and shell parts;
2. It can process parts that can not be processed or difficult to process by common machine tools, such as complex curve parts described by mathematical model and 3D space surface parts;
3. The parts that need to be processed by multiple processes after one clamping and positioning are processed;
4. The high precision and reliable quality of the NC device are generally 0.001mm, and the high precision CNC system can reach 0.1 μ M. in addition, the operation error of the operators is avoided;
5. The production automation is high, which can reduce the labor intensity of the operator. It is conducive to the automation of production management;
6. The production efficiency is high, and the special process equipment such as special fixture is not required for CNC milling machine. When replacing workpieces, high-speed computer gong processing only needs to call the processing program, clamping tool and adjusting tool data stored in the NC device, thus greatly shortens the production cycle. Secondly, CNC milling machine has the functions of milling machine, boring machine and drilling machine, which makes the working procedure highly concentrated and greatly improves the production efficiency. In addition, the spindle speed and feed speed of CNC milling machine are stepless, so it is helpful to choose the best cutting amount.

2、 System classification of computer gongs processed by Shenzhen gongs:

① Cooling system. The cooling system of the machine tool is composed of cooling pump, water outlet pipe, return pipe, switch and nozzle. The cooling pump is installed in the inner cavity of the machine base. The cooling pump pumps the cutting fluid from the storage tank in the base to the outlet pipe, and then ejects through the nozzle to cool the cutting area.

② Lubrication system and method. Lubrication system is composed of manual oil donation pump, oil distributor, throttle valve, oil pipe, etc. The machine tool adopts periodic lubrication method, uses the manual lubrication oil pump, through the oil distributor to lubricate the spindle sleeve, the longitudinal and horizontal guide rail and the three-way ball screw, so as to improve the service life of the machine tool.

From the characteristics of digital control technology, because the servo motor is used in CNC machine tool, it should

1. The height of slide guide rail shall be at least 1 / 3 of that of slide block to ensure the stability and smooth sliding of sliding block.
2. Attention should be paid to the opening of lubricating groove where there is sliding friction. In order to prevent the outflow of lubricating oil, the groove should not be opened into “open type”, but should be “closed type”. Generally, the annular oil storage tank can be directly milled on the milling machine with a single cutter.
3. For the cavity of fixed mold core, the small mold is generally cut by line cutting, which can improve the precision of the mold; while the mold cavity of the larger mold is generally processed in the form of milling, pay attention to its perpendicularity during processing, and in order to prevent the mold core from not in place during assembly, the milling depth should be 0.2mm around the mold frame, and the hole position should be pre drilled on the mold frame at the corner, which will form void avoidance after milling. Prevent the interference of the assembly die (chamfering can also be done on the die).
4. The angle of 1 ° should be added to the interpenetration between the insert and the mold, between the mold core and the mold core, and between the mold core and the mold frame, so as to prevent collision and injury during assembly.
5. The length tolerance and size tolerance of the insertion part are -0.02, -0.10 and + 0.02 respectively.
6. The tolerance from the bottom of the c-angle to the c-angle is + 0.01 to prevent the burring.
7. The main part of the body mould is made of NAK80 material, and the material of skh9 and SKH51 (material treatment: nitriding treatment is also allowed), and Viking material can be used if necessary.
8. After drawing the parts, the position and size of the slider should be determined first to prevent interference and insufficient strength, and then the mold kernel size method should be determined.
9. The tolerance of the size of the insert is – 0.01, and the tolerance of the hole in the mold is + 0. 01 (transition fit).
10. The sharp corner of wire cut square hole on the mold core is excessive with r0.20, and the corresponding entry part is also r0.20, so as to influence the wire diameter during wire cutting, and prevent the sharp corner part from abrasion and edge overflow.
11. The small pit size corresponding to the positioning ball (wave bead) is generally conical hole with bottom diameter of φ 3 and angle of 90 ° to 120 °.
12. The draft angle of the fixed side should be greater than that of the movable side. The high-speed computer gongs can be used to process the mold leaving on the movable side. Moreover, it can prevent the parts from deformation, especially for the parts with thin wall and easy deformation in length, and the uneven pulling force on the fixed side will easily cause the parts to warp or stay on the fixed side.
13. For the parts with large side core pulling force and strict part precision requirements, the secondary core pulling structure should be adopted.
14. The slope of inclined tip + 2 ° = the slope of hold down block (generally 18 ° or 20 ° or 22 °)
15. When assembling molds, the following habits should be formed:

a. Clean the surface of mold core, cavity, runner, runner plate and parting surface with air gun.

b. Before assembly, polish the surface of mold core, mold cavity, insert and parting surface with oilstone to facilitate smooth assembly.

c. Pay attention to the angle cleaning to prevent interference and bruise.

d. Before assembly, we should consider how to carry out the following work.

1. The side pressing block of large mold core should be designed to be locked and the bottom should be 0.5-1.0mm below the parting surface to prevent interference.
2. The shrinkage rate of PC + GF20 is 3 / 1000, and the shrinkage efficiency in the direction of material flow with GF is less than that in the direction of vertical material flow, which is different from other materials.
3. The contraction rate of POM was normal 20 / 1000, but sometimes it was 30 / 1000.
4. In order to prevent the parts from being scratched by the latent gate when the part is ejected, a wedge-shaped block is added 2-4mm away from the latent gate. The height of the wedge is about half of the runner, and the included angle is 10 ° on one side. The gate will be broken when ejected.
5. The main channel pulling well adopts an inverted cone with a depth of 8-10 mm, an included angle of 10 ° on one side, and a top diameter of a wide flow channel. The advantage of this method is that it can prevent the pulling material from one side grinding into a wedge shape from hooking the flow channel during ejection, resulting in poor parting.

There are two kinds of opening and closing devices: 1. Made of rubber, the deformation is adjusted by the central screw to adjust the tension. 2. Made of spring steel. Their functions are: delay the opening time of movable side and fixed side, apply to small nozzle mold (three plate mold) or apply to secondary ejection system.

1. In order to ensure whether the ejector pin and inclined pin of the mold are reset, some molds are equipped with early return mechanism (female is installed on 108 plate, male is installed on 102 plate, male is similar to thimble, the bottom is blocked with headless screw, and two are generally arranged) or microswitch (between 108 and 109 boards [power mounting element]).
2. Considering the screw length of the injection molding machine when clamping the mold, it is necessary to pay attention to the thickness of the upper and lower fixing plates (generally about 40mm). If necessary, the four corners should be milled lower. At the same time, in order to improve the safety, four bolt holes can be drilled on the upper and lower fixed plates according to the position of the upper holes of the injection molding machine.
3. The forming end of the oblique pin has a straight face, which is generally 4-6mm long. In order to slide the inclined pin between 107 and 108 plates during ejection, an R angle of 0.5mm-1mm should be poured at the bottom.
4. For the appearance that needs to be bitten, the degree of biting should be considered in the design of draft angle, so as to avoid the appearance strain. For some protruding parts, the cross-section will become larger after biting, so the single side should be 0.02-0.03 smaller in actual processing.
5. Considering that the mold closing between the fixed side and the movable side will result in break, the fixed side is 0.03-0.05 smaller than that of the movable side.
6. In the mould with sliding block, sometimes it is necessary to set oil groove on the inclined surface of the sliding block and the pressing block; in addition, if the forming is not affected, the processing efficiency of opening oil groove on the upper surface of the template is higher than that on the bottom of the sliding block.
7. The parting surface should not be selected at the required position of the surface.
8. The shrinkage of the fiber with fiber is 1-2% smaller than that of the flow direction, which is larger than that perpendicular to the flow direction; otherwise, it is the opposite.
9. The shrinkage rate of the addendum circle is 1-2 thousandth less than that of the root circle.
10. When the die is used for a section

Do CNC deep hole processing friends should know that CNC processing, deep hole processing is the most difficult. The so-called deep hole machining is the processing that the ratio of the length of the hole to the diameter of the hole is greater than 10 times. The deep hole processing is applied in some industrial fields of the country, such as the national military rocket body and the barrel of various guns. In these application fields, some require very high quality and precision of machining, and some require high cutting ability of processing materials The so-called CNC is the abbreviation of computer numerical control machine tool, which is the technology required for programmed control, automation and high-tech.

CNC technology is applied to deep hole processing. Because the processing technology and method of computer gong machining are very complex, few people use CNC machining center to process deep hole. If this technology is used, first of all, we should transform the CNC machining center to vibration deep hole drilling machine, and combine the advanced deep hole machining vibration cutting technology with AC frequency conversion speed regulation technology Together, it forms a kind of precise professional processing technology. This kind of precise CNC deep hole processing technology effectively applies the vibration cutting technology to the drilling process. On the basis of the traditional deep processing technology, the amplitude and frequency of the regular vibration of the tool used are given. In the process of cutting tool running, the cutting work is completed by vibration at the same time, and the cutting thickness changes periodically, so as to achieve the purpose of NC cutting according to the predetermined shape and size. Thus, the problem of chip removal interruption in CNC deep hole machining is effectively solved, and the quality and efficiency of deep hole machining are improved.

After years of efforts, the development of domestic ultra precision machining equipment has begun to take shape. The indicators of many equipment for machining mechanical parts, including aspheric surface composite machining system, have reached or approached the world advanced level In terms of reliability and operability, there is still a certain gap. How to better play the role of equipment requires further human and material investment. For example, the nano sys-300 aspheric surface compound processing equipment of our laboratory has been in the production line service since it was delivered to the user in May 2003. It has processed many batches of task parts, which can fully meet the requirements of users in terms of processing accuracy, but there is still much room for improvement in other aspects, such as operability and reliability. Therefore, it is necessary to strengthen the research on the reliability and practicability of ultra precision machining technology.

With the development of science and technology, more and more advanced new functional materials and structural materials will be applied, including new high strength, high hardness materials, intelligent materials, new semiconductor materials, and so on. For example, the processing technology of SiC reinforced composite materials used in satellite cameras, the ultra precision turning technology of infrared materials such as germanium, monocrystalline silicon and calcium fluoride glass, and the flying cutting process of KDP crystal (laser fusion), etc.

MEMS processing technology mainly includes silicon planar process and bulk silicon process developed from semiconductor processing technology. Since the mid-1980s, LIGA technology, which uses X-ray lithography, electroforming and injection molding, was born, forming another MEMS processing system. The processing technology of MEMS can include silicon micromachining for surface and bulk machining, Liga machining and quasi Liga machining using UV lithography, micro EDM, ultrasonic machining, plasma machining, laser machining, ion beam machining, electron beam machining, stereolithography, etc.

However, the components of these micromachines are various and complicated. In order to make the performance of micromachines really pass the standard and reach the practical level, it is necessary to improve the manufacturing technology and equipment level of micro mechanical parts as soon as possible. At present, lithography is the most mature technology in the manufacturing process of micro mechanical parts. Most of the classic micro mechanical parts are made by lithography or electroforming technology. However, the micromechanical parts processed by these mature technologies can only be two-dimensional (or quasi three-dimensional), and the actual three-dimensional shape parts can not be completed by lithography technology. There are many three-dimensional micro parts in CNC machining center, such as micro mold, micro thread with diameter of 70 μ m, micro rack, pin with diameter of 50 μ m, stepped shaft with diameter of 200 μ m, 100 μ m and 50 μ m, and rotary polishing with outer diameter of 300 μ M The processing of these typical three-dimensional micro parts can not be realized not only by lithography, three beam processing, but also by traditional mechanical manufacturing system. Therefore, it is necessary to develop and develop a micro manufacturing system according to the characteristics of three-dimensional micro machines. In this new concept manufacturing system, the processing, detection and assembly of micro machine parts can be realized. The manufacturing system of micro machine, which is composed of micro equipment, is called micro manufacturing system. The technical problems include the processing, detection and assembly of micro machine parts. The research work in this field is mainly concentrated in Japan and the United States. In this regard, Japan first put forward the concept of micro desktop factory.

However, it is not necessary to use micromachining machine tools to process micro mechanical parts, such as the characteristics of machine tools for processing instrument parts

After refitting ordinary machine tools into economical numerical control lathes, the work efficiency can be increased by 1-4 times, the scrap rate can be reduced, the product quality can be improved, and the labor intensity of workers can be reduced. Renovation costs are usually recovered in about a year.

Generally, single board microcomputer is used as control device for high-speed Gong machining, and stepping motor is used as actuator to transform ordinary machine tool into economical numerical control lathe. The modified machine tool not only retains the versatility of the original machine tool, but also adds many features that traditional machine tools do not have, such as automatic tool setting, gap compensation, automatic feed speed adjustment, automatic return to the original point and so on. This kind of machine tool is especially suitable for the frequent and rotational processing of rod, shaft, disc parts and parts with taper and spherical surface.

Economic CNC lathes can be divided into three types according to the driving system

1. Open loop system driven by stepping motor. This kind of system is widely used. Economical CNC lathe can finish the machining of cylinder, plane, cone, curved surface and thread.
2. Point position numerical control system driven by asynchronous motor or DC motor, grating measurement feedback.
3. A semi closed loop system driven by DC servo motor for high speed Gong machining. This kind of system is mainly used for new machine tools because of its high price.
4. High speed computer gongs use precision level instrument and other detection tools, mainly by adjusting the pad iron way to fine adjust the level of the main bed of the machine tool, so that the geometric accuracy of the machine tool can reach the allowable tolerance range;
5. For the automatic tool change device, adjust the position of the tool magazine, manipulator, travel parameters, etc., and then check the action with the command, which is required to be accurate;
6. For the machine tool with APC automatic exchange table, after adjusting the relative position, carry out automatic load exchange;
7. After the adjustment of the machine tool, carefully check whether the parameter setting values in the numerical control system and the programmable controller conform to the data specified in the random index, and then test the main operation functions, safety measures, execution of common instructions, etc.
8. High speed computer gong to check the normal operation of auxiliary functions and accessories of the machine tool. It is usually composed of CNC system, main drive system, feed servo system, cooling smooth system, etc

It is used to clamp the tool and rotate the tool. The spindle speed scale and output torque have a direct impact on the machining. 2. The feed servo system is composed of feed motor and feed actuator. According to the feed rate set by the program, the relative motion between the tool and the workpiece is completed, including linear feed motion and rotary motion. 3. Control system CNC milling machine motion control in the middle of the implementation of NC machining program control machine tools for processing. Computer gong processing, Dongguan computer gong processing, high speed computer gong processing, mechanical parts processing, computer gong processing, auxiliary equipment such as hydraulic, pneumatic, smooth, cooling system, chip removal and protection equipment. 5. The base parts of high-speed computer gong machine tools usually refer to the base, column, beam, etc., which are the foundation and structure of the whole machine tool.

CNC machining center power supply has three conditions: the first point, the source on button closed. Second, the power off button is closed. Third, the external alarm contact is opened.

The alarm light of power supply unit of CNC machining center is on: the fuse of 24 V output voltage is fused, and + 24 V voltage is used on 1.9 “display screen, as shown in the figure below. Check whether + 24 V is short circuited to the ground. 2. The display / manual data input board is poor. During the use of the center, the tool imbalance may occur. If not adjusted in time, it will affect the processing effect. Therefore, we should always pay attention to the tool balance of CNC machining center. What are the main reasons for the imbalance of the handle?

The main reason for CNC machining is that the tool design is asymmetric, there are defects in the tool body, and all the adjustment of the tool. The correct balance of the tool can significantly reduce noise and vibration, which increases the tool life and improves the accuracy consistency of parts.

The centrifugal force of CNC machining center is proportional to the square of velocity to amplify the vibration caused by unbalance. The vibration increase of NC machining center caused by this will minimize the life of bearing bush, bearing, shaft, spindle and gear.

Before balancing the tool in CNC machining center, it is necessary to measure the unbalance and the angle position of each selected correction plane. These variables are measured on two general types of balancing machines: non rotating or gravity machines are used to measure single plane unbalance, while rotary or centrifuge is used to measure single plane or two plane unbalance.

After measuring the magnitude and angle of the unbalance in the correct plane, you can correct it by adding or removing material from the workpiece. For the components which are not tools, the most widely used material adding method of drilling center is welding counterweight on the components.

CNC machining (CNC machining) refers to the processing with CNC machining tools. CNC index controlled machine tool is programmed by NC machining language, usually G code. NC machining G code language tells CNC machine tool which Cartesian position coordinates, and controls the tool feed speed and spindle speed, as well as tool converter, coolant and other functions. Compared with manual machining, CNC machining has great advantages, such as the parts produced by CNC machining are very accurate and repeatable; CNC machining can produce parts with complex shapes that cannot be completed by manual processing. CNC machining technology has been widely promoted, most of the machining workshops have the ability of NC machining. The most common NC machining methods in typical machining workshops are CNC milling, CNC lathe and CNC EDM wire cutting (WEDM). The tool for NC milling is called CNC milling machine or CNC machining center. CNC turning lathe is called CNC lathe center. NC machining G code can be manually programmed, but usually the machining workshop uses CAM software to automatically read CAD file and generate G code program to control NC machine tool.

The influence of vibration of cutter teeth on the surface roughness and tool life. In order to prevent the decline of machining accuracy and tool life, the selected machining center must be equipped with a spindle with excellent dynamic balance performance, and the selected boring tool must also have high dynamic balance characteristics. Especially for the cutter tooth part of boring tools, the geometry, tool material and clamping mode suitable for high-speed cutting should be selected. In order to improve the machining efficiency, the feed rate should be increased on the premise of obtaining the same surface roughness. However, the increase of feed rate should be enough, otherwise it will increase the cutting resistance, which is not conducive to improving the processing efficiency. The cutting edge should be set with negative chamfering less than 0.1 mm, which can effectively maintain the stability of tool life.

In addition to CNC cutting method for precision machining of holes, boring and reaming can also be used for high-precision machining of holes. With the high-speed spindle of machining center, boring tools can be used for high-speed and precision machining of holes. It is reported that the cutting speed can be increased to more than 1500m / min when the diameter of boring is about 40mm on aluminum alloy. This cutting speed can also be used when using CBN sintered body as cutting edge to process steel, cast iron and high hardness steel. It is predicted that the high speed of boring will be popularized rapidly in the future.

As for the tool material, it depends on the nature of the material being processed. For example, when machining steel below 40HRC, cermet tool can be selected. Under the high-speed cutting condition of V = 300m / min, good surface roughness and long tool life can be obtained. Coated cemented carbide tools are suitable for high-speed cutting of steels below 60HRC. The tool life is very stable, but the cutting speed is slightly lower than cermet tools.

Sintered tool is suitable for machining high hardness steel, cast iron and other materials. The cutting speed can reach more than 1000m / min, and the tool life is very stable. Proper chamfering should be carried out on the cutting edge of CBN cutter teeth in CNC machining, which is very beneficial to stable high-speed cutting and prolonging tool life. In ultra-high speed cutting of nonferrous metals and non-metallic materials such as aluminum alloy, diamond sintered body tool can be selected. This kind of cutting tool is stable and has a long service life. It should be noted that when using diamond tools, the blade belt must be chamfered, which is an important condition to ensure the stability of cutting.

The power control equipment of AC motor is controlled by the frequency mode of motor power supply. In CNC machine tools, the frequency converter is mainly used to control the action of the spindle.

The blade of end mounted structure milling cutter (as shown in FIG. 10) is fixed on the cutter groove with only one screw, which is simple in structure and convenient in rotation. Although there are few tool parts in mechanical parts processing plant, it is difficult to process the cutter body. Generally, it needs five coordinate machining center for machining. Since the blade is clamped by cutting force, the clamping force increases with the increase of cutting force, so the clamping element can be omitted and the chip holding space is increased. Because the blade is installed in tangential direction, the section of cemented carbide in the direction of cutting force is large, so it can be used for large cutting depth and large cutting distance. This kind of milling cutter is suitable for heavy and medium milling.

The angle of milling cutter includes front angle, back angle, main deflection angle, auxiliary deflection angle, edge inclination angle, etc. In order to meet the different processing needs, there are a variety of angle combination types. Among the various angles, the main deflection angle and rake angle are the main ones (the main deflection angle and rake angle of the cutter are generally clearly stated in the product samples of the manufacturer).

Main deflection angle KR

The main deflection angle is the angle between the cutting edge and the cutting plane, as shown in FIG. 11. The main deflection angles of milling cutter are 90 °, 88 °, 75 °, 70 °, 60 ° and 45 ° etc.

Principal deflection angle

The main deflection angle has a great influence on the radial cutting force and cutting depth. The size of radial cutting force directly affects the cutting power and anti vibration performance of cutting tools. The smaller the main deflection angle of the milling cutter is, the smaller the radial cutting force is, the better the vibration resistance is, but the cutting depth is also reduced.

The main deflection angle of 90 ° is selected when milling the plane with shoulder, and CNC machining is not generally used for pure plane machining. This kind of tool has good versatility (not only can process step surface, but also can process plane), so it can be selected in single piece and small batch processing. Because the radial cutting force of this kind of cutting tool is equal to the cutting force, the feed resistance is large, and it is easy to vibrate. When machining the plane with shoulder, the milling cutter with 88 ° main deflection angle can also be selected. Compared with the milling cutter with 90 ° main deflection angle, its cutting performance is improved to some extent.

The main deflection angle of 60 ° to 75 ° is suitable for rough machining of plane milling. Due to the obvious reduction of radial cutting force (especially at 60 degrees), its vibration resistance is greatly improved, and the cutting is smooth and light. Therefore, it should be preferred in plane machining. 75 ° main deflection angle milling cutter is a general-purpose tool with wide application range; 60 ° main deflection angle milling cutter is mainly used for rough milling and semi finishing milling on boring and milling machines and machining centers.

The radial cutting force of this kind of milling cutter with 45 ° main deflection angle is greatly reduced, which is approximately equal to the axial cutting force. The cutting load is distributed on the longer cutting edge, and has good vibration resistance. It is suitable for the machining occasions with longer spindle overhang of boring and milling machine. When machining plane with this kind of cutting tool, the damage rate of blade is low and the durability is high; when machining iron castings, the edge of the workpiece is not easy to break.

Anterior angle γ

The rake angle of milling cutter can be divided into radial rake angle γ F and axial rake angle γ P. the radial rake angle γ f mainly affects the cutting power; the axial rake angle γ P affects the chip formation and the direction of axial force. When γ P is positive, the chip will fly away from the machining surface.

Anterior horn

The common combination forms of front angle are as follows:

The milling cutter with double negative rake angle and double negative rake angle usually adopts square (or rectangular) blade without back angle. The cutter has many cutting edges (generally 8), high strength and good impact resistance, which is suitable for rough machining of cast steel and cast iron. Because the chip shrinkage ratio is large, it needs a large cutting force, so the machine tool has higher power and higher rigidity. Because the forward angle of the shaft is negative, the chip can not flow out automatically. When cutting ductile materials, chip accretion and tool vibration are easy to occur.

It is suggested to use double cutting tool with negative rake angle when machining. When double positive rake angle milling cutter is used to produce chipping edge (i.e. large impact load), the double negative rake angle milling cutter should also be preferred when the machine tool allows.

The milling cutter with double positive rake angle and double positive rake angle adopts the blade with back angle, which has small wedge angle and sharp cutting edge. Because of the small shrinkage ratio of the chip, the cutting power consumed is small, and the chip is discharged in a spiral shape, which is not easy to form a chip accumulation lump. This kind of milling cutter is most suitable for cutting soft materials, stainless steel, heat-resistant steel and other materials. For the machine tools with poor rigidity (such as boring and milling machines with long spindle overhanging), low power and machining welded structural parts, double positive rake angle milling cutters should also be preferred.

Positive and negative rake angle (axial positive rake angle, radial negative rake angle) this kind of milling cutter combines the advantages of double positive rake angle and double negative rake angle milling cutter. The axial positive rake angle is conducive to the formation and discharge of chips; the radial negative rake angle can improve the edge strength and impact resistance. This kind of milling cutter has the advantages of smooth cutting, smooth chip removal and high metal removal rate, which is suitable for large allowance milling. Computer gong processing, Dongguan computer gong processing, high speed computer gong processing, mechanical parts processing, computer gong processing, Walter’s tangential tooth distribution heavy cutting milling cutter f2265 is a milling cutter with axial positive rake angle and radial negative rake angle structure.

The number of milling cutter teeth is large, which can improve the production efficiency. However, due to the limitation of chip holding space, cutter tooth strength, machine tool power and rigidity, the number of teeth of milling cutter with different diameters has corresponding regulations. In order to meet the needs of different users, there are three types of milling cutters with the same diameter: coarse teeth, medium teeth and dense teeth.

Rough tooth milling cutter is suitable for large allowance rough machining of ordinary machine tools and milling of soft materials or large cutting width; when the power of machine tool is small, in order to make cutting stable, coarse tooth milling cutter is often used.

The middle gear milling cutter is a universal series, which makes

Input shaft: forging and blank making → normalizing → finishing turning → gear rubbing → drilling → gear shaping → undercut angle → hobbing → shaving → heat treatment → grinding → meshing and finishing.

Output shaft: forging billet → normalizing → finishing turning → rolling gear → shaving → heat treatment → grinding → meshing and finishing.

1. Specific process flow

(1) Forging billet

Hot die forging is a widely used blank forging process for automobile gear parts. Computer gong processing, Dongguan computer gong processing, high speed computer gong processing, mechanical parts processing, computer gong processing

Hot forging and cold extrusion are widely used in the past. In recent years, cross wedge rolling technology has been widely used in shaft machining. This technology is especially suitable for the production of complex stepped shafts. It not only has high precision, small machining allowance, but also has high production efficiency.

(2) Normalizing

The purpose of this process is to obtain the hardness suitable for subsequent gear cutting and to prepare the microstructure for the final heat treatment, so as to effectively reduce the heat treatment deformation. Due to the influence of personnel, equipment and environment, the normal normalizing can not control the cooling rate and cooling uniformity of workpiece, resulting in large hardness dispersion and uneven microstructure, which directly affects machining and final heat treatment.

(3) Finish turning

In order to meet the positioning requirements of high-precision gear machining, CNC lathe is used for the finish turning of gear blank. First, the inner hole and locating end face of the gear are machined, and then the machining of the other end face and outer diameter is completed synchronously. It not only ensures the perpendicularity requirement between the inner hole and the locating end face, but also ensures the small size dispersion in the mass production of gear blanks. Thus, the accuracy of gear blank is improved and the machining quality of subsequent gear is ensured.

There are mainly three ways of positioning datum and clamping for shaft parts processing

Positioning by the center hole of the workpiece: in the machining of the shaft, the coaxiality of the outer circle surface and end face of the part, and the perpendicularity of the end face to the rotating axis are the main items of their mutual position accuracy. The design basis of these surfaces is generally the center line of the shaft. If two center holes are used for positioning, it is in line with the principle of datum coincidence.

1. Outer circle and central hole as the positioning reference (one clip and one top): Although the centering accuracy is high, the rigidity is poor, especially when machining heavy workpieces, and the cutting parameters cannot be too large.

In rough machining, in order to improve the rigidity of the parts, the cylindrical surface of the shaft and a central hole can be used as the positioning reference. This positioning method can bear large cutting torque and is the most common positioning method for shaft parts.

1. Take two cylindrical surfaces as positioning datum: when machining the inner hole of hollow shaft (for example: machining the inner hole of Morse taper on the machine tool), the central hole cannot be used as the positioning reference, and the two outer cylindrical surfaces of the shaft can be used as the positioning reference. When the workpiece is the spindle of machine tool, the two supporting Journal (assembly reference) is often used as the positioning reference, which can ensure the coaxiality requirement of the taper hole relative to the supporting journal, and eliminate the error caused by the non coincidence of the reference.

CNC machining refers to the processing with CNC machining tools. CNC index controlled machine tool is programmed by NC machining language, usually G code. NC machining G code language tells CNC machine tool which Cartesian position coordinates, and controls the tool feed speed and spindle speed, as well as tool converter, coolant and other functions. Compared with manual machining, CNC machining has great advantages, such as the parts produced by CNC machining are very accurate and repeatable; CNC machining can produce parts with complex shapes that cannot be completed by manual processing. CNC machining technology has been widely promoted, most of the machining workshops have the ability of NC machining. The most common NC machining methods in typical machining workshops are CNC milling, CNC lathe and CNC EDM wire cutting (WEDM). The tool for NC milling is called CNC milling machine or CNC machining center. CNC turning lathe is called CNC lathe center. NC machining G code can be manually programmed, but usually the machining workshop uses CAM software to automatically read CAD file and generate G code program to control NC machine tool. Leading CNC machine tool brands include Hass, DMG (Deckel MAHO GILDEMEISTER), Mazak, Mori Seiki, fadal and wasino.

Several groups of common instructions for CNC machining

1、 Pause instruction g04x (U)_ /P_ It refers to the tool pause time (feed stop, spindle does not stop), the value after address P or X is the pause time. The value after X should have a decimal point. Otherwise, it should be calculated by one thousandth of this value in seconds (s). The value after P cannot have a decimal point (i.e., an integer), and the unit is Ms. For example, G04 x2.0; or G04 X2000; pause for 2 seconds G04 P2000; but in some hole series processing instructions (such as g82, G88 and g89), in order to ensure the roughness of the hole bottom, when the tool is machined to the hole bottom, there must be a pause time, which can only be expressed by the address P. if the address x is used, the control system thinks that x is the x-axis coordinate value for execution. For example, g82x100.0y100.0z-20.0r5.0f200p2000; drilling (100.0100.0) to the bottom of the hole for 2 seconds; g82x100.0y100.0z-20.0r5.0f200x2.0; drilling (2.0100.0) to the bottom of the hole will not be suspended.

2、 The difference and connection of M00, M01, M02 and M30 are program unconditional pause instructions. When the program is executed, the feed stops and the spindle stops. To restart the program, you must first return to the og state, press CW (spindle forward rotation) to start the spindle, and then return to the auto state and press the start key to start the program. M01 is the program selective pause instruction. The op stop key on the control panel must be opened before the program is executed. The effect after execution is the same as that of M00. Restart the program as above. M00 and M01 are often used in the inspection or chip removal of workpiece size in the process of machining. M02 is the end instruction of main program. Execute this command, feed stop, spindle stop, coolant off. But the program cursor stops at the end of the program. M30 is the main program end instruction. The function is the same as that of M02, except that the cursor returns to the program head position, regardless of whether there are other program segments after M30.

3、 The meaning of the address D and H is the same. The tool compensation parameters D and H have the same function and can be interchanged arbitrarily. They all represent the address name of the compensation register in the CNC system, but the specific compensation value is determined by the compensation number address behind them. However, in order to prevent errors in the machining center, generally, h is the tool length compensation address, the compensation number is from No. 1 to No. 20, D is the tool radius compensation address, and the compensation number starts from No. 21 (tool magazine of 20 tools). For example, g00g43h1z100.0; g01g41d21x20.0y35.0f200;

4、 Mirror instruction mirror processing instruction M21, M22, M23. When only the x-axis or y-axis is mirrored, the cutting sequence (forward milling and reverse milling), cutter compensation direction and circular interpolation steering will be opposite to the actual program. When the x-axis and y-axis are mirrored at the same time, the tool feed sequence, tool compensation direction and circular interpolation direction remain unchanged. Note: after using the mirror instruction, M23 must be used to cancel, so as not to affect the following program. In G90 mode, if mirror or cancel command is used, it can be used only after returning to the origin of workpiece coordinate system. Otherwise, the NC system can not calculate the motion track behind, which will lead to the phenomenon of random tool walking. At this time, it is necessary to implement manual origin reset operation to solve the problem. The spindle rotation does not change with the mirror command.

5、 Circular interpolation instruction G02 is clockwise interpolation, G03 is counter clockwise interpolation, in XY plane, the format is as follows: G02 / g03x_ Y_ I_ K_ F_ Or G02 / g 03 x_ Y_ R_ F_ Where x and y are the coordinates of the end point of the arc, I and j are the increment values from the starting point of the arc to the center of the circle on the X and Y axes, R is the radius of the arc, and F is the feed rate. In circular arc cutting, it should be noted that Q ≤ 180 ° R is positive; Q > 180 ° R is negative; I and K can also be specified by R. when both are specified, R command has priority, I and K are invalid; R cannot be used for whole circle cutting, and can only be programmed with I, J and K, because there are countless circles with the same radius passing through the same point. When I and K are zero, they can be omitted; regardless of G90 or G91 mode, I, J, K are programmed according to relative coordinates; when circular interpolation, tool compensation instruction G41 / G42 cannot be used.

6、 The advantages and disadvantages between G92 and G54-G59 are the coordinate system set before machining, while G92 is the coordinate system set in the program. If G54-G59 is used, there is no need to use G92, otherwise G54-G59 will be damaged