Monthly Archive January 20, 2021

Grinding method of CNC lathe

The structure of computer gong machining center is mainly composed of the following parts.

  1. Basic components. It is the basic structure of the machining center, which is composed of bed, column and worktable. They mainly bear the static load of the machining center and the cutting load during machining, so they must have enough stiffness. These large parts can be cast iron or welded steel structural parts. They are the largest volume and weight parts in the machining center.
  2. Spindle assembly. It is composed of spindle box, spindle motor, spindle and spindle bearing. The start, stop and speed change of the spindle are all controlled by the numerical control system, and the tool installed on the spindle participates in the cutting movement, which is the power output component of cutting.
  3. Numerical control system. The CNC part of machining is composed of CNC device, PLC, servo drive device and operation panel. It is the control center to execute the sequence control action and complete the machining process.
  4. Automatic tool changing system. It is composed of tool magazine, manipulator and other parts. When the tool needs to be changed, the numerical control system sends out a command, and the manipulator (or by other means) takes the tool out of the tool magazine and loads it into the spindle hole.
  5. Auxiliary devices. It includes vortex sliding, cooling, chip removal, protection, hydraulic, pneumatic and detection system. Although these devices do not directly participate in the cutting movement, they play a role in ensuring the machining efficiency, machining accuracy and reliability of the machining center, so they are also indispensable parts of the machining center.

Tool grinding method of CNC lathe for high speed CNC machining posture and method of tool grinding of CNC lathe are as follows:

  1. People stand on the side of the grinder to prevent the fragments from flying out to hurt people when the grinding wheel is broken;
  2. The distance between the two hands holding the knife is released, and the two elbows are clamped at the waist to reduce the shaking when grinding the knife;
  3. When grinding, the turning tool should be placed in the horizontal center of the grinding wheel, and the tool tip should be tilted up about 3 ° to 8 ° slightly. After the turning tool contacts the grinding wheel, it should move horizontally in the left and right directions. When the turning tool leaves the grinding wheel, it should be lifted up to prevent the grinding edge from being damaged by the grinding wheel;
  4. When grinding the flank, the end of the cutter bar is deflected to the left by an angle of main deflection angle; when grinding the flank, the end of the cutter bar is deflected to the right by an angle of auxiliary deflection angle;
  5. When sharpening the arc of the tool tip, the front end of the tool is usually held by the left hand as the fulcrum, and the rear end of the tool is rotated by the right hand.

The precautions for CNC lathe tool grinding are as follows:

  1. Before grinding tools, first check whether the grinding wheel has cracks and whether the grinding wheel shaft nut is tightened, and use it after trial run, so as to avoid the grinding wheel breaking or flying out to hurt people.
  2. Don’t use too much force on the sharpener, otherwise it will make the hand slip and touch the grinding wheel surface, resulting in industrial accidents.
  3. Wear protective glasses when sharpening to avoid grit and iron filings flying into the eyes.
  4. Do not stand in the direction of rotation of the grinding wheel when grinding, in case of accidents.
  5. When grinding the small cutter head, the small cutter head must be installed on the cutter bar.
  6. The clearance between the grinding wheel bracket and the grinding wheel shall not be greater than 3 mm. If it is too large, it shall be adjusted properly.

CNC five axis computer gong processing quality components

Five axis machining is a mode of NC machining.

According to ISO, the right-hand rectangular coordinate system is used to describe the motion of CNC machine tools. The coordinate axis parallel to the spindle is defined as Z axis, and the rotation coordinates around x, y and Z axis are a, B and C respectively. The movement of each coordinate axis can be realized by the table or by the movement of the tool, but the direction is defined by the movement direction of the tool relative to the workpiece. Generally, five axis linkage refers to the linear interpolation movement of any five coordinates in X, y, Z, a, B and C.

In other words, five axis refers to x, y, Z three moving axes plus any two rotating axes. Compared with the common three-axis (x, y, Z three degrees of freedom) machining, five axis machining means that when machining the parts with complex geometry, the machining tools need to be able to locate and connect in the five degrees of freedom.

The machine tool used in five axis machining is usually called five axis machine tool or five axis machining center. Five axis machining is often used in aerospace field to process body parts, turbine parts and impellers with free-form surfaces. Five axis machine tool can process different sides of the workpiece without changing the position of the workpiece on the machine tool, which can greatly improve the processing efficiency of prismatic parts. Five axis machining center manufacturing technology features:

With the continuous development of mold manufacturing technology, some weaknesses of vertical machining center itself are more and more obvious. Dongguan high-speed computer gong processing, modern mold processing generally uses ball end milling cutter to process, ball end milling cutter brings obvious benefits in mold processing, but if the vertical machining center is used, its bottom surface linear speed is zero, so the bottom surface finish is very poor, if the five axis machining center processing technology is used to process the mold, the above shortcomings can be overcome.

The use of five axis machining center makes the workpiece clamping easier. There is no need for special fixture during processing, which reduces the cost of fixture, avoids multiple clamping, and improves the accuracy of mold processing. Five axis technology can reduce the number of fixtures.

In addition, because the five axis machining center can save a lot of special tools in processing, so it reduces the cost of tools. Five axis machining center can increase the effective cutting edge length of the tool, reduce the cutting force, improve the service life of the tool and reduce the cost. Using five axis machining center to process the mold can quickly complete the mold processing, fast delivery, better guarantee the processing quality of the mold, make the mold processing easier, and make the mold modification easier. In the traditional mold processing, the vertical machining center is generally used to complete the workpiece milling.

Machining center a machine tool, centralized milling machine, drilling machine, tapping machine and other equipment functions, it can reduce the number of enterprise machine tools, because one person can operate multiple machining centers at the same time, reduce the operator, labor costs correspondingly reduced; in addition, it has a CNC machining center.

Five axis machining center has strong adaptability and good flexibility. The machining center can easily carry out multiple different processing procedures for box parts, such as drilling, reaming, reaming, boring, tapping, milling end face and trenching, so it can process parts with complex contour shape or difficult to control size, such as fan blade, automobile engine box and so on.

Five axis machining center supporting fixture stiffness, machining center’s own stiffness and accuracy maintenance requirements are very high; machining center technology is complex, and has high requirements for use, maintenance and management; machining center has a large one-time investment, and needs to be equipped with other auxiliary devices, such as CNC tool system. The operation and monitoring of CNC machining axis-0 are all completed in the control unit of CNC machine tool, which is the brain of CNC machine tool.

Compared with ordinary machine tools, CNC machine tools have the following characteristics:

High machining accuracy and stable machining quality;

It can carry out multi coordinate linkage and process complex parts;

When the machining parts are changed, generally only the NC program needs to be changed, which can save the production preparation time;

The machine tool itself has high precision, high rigidity, and can select favorable processing amount, with high productivity (generally 3-5 times of that of ordinary machine tool);

High degree of automation of machine tool can reduce labor intensity;

Five axis CNC machining requires higher quality of operators and higher technical requirements of maintenance personnel. CNC machine tools are generally composed of the following parts:

A. Host: it is the theme of CNC machine tools, including machine body, column, spindle, feed mechanism and other mechanical parts. It is used to complete a variety of cutting machinery.

CNC lathe parts processing design

CNC processing and production design is based on the actual CNC processing technology level and production capacity of the enterprise, emphasizing the combination of design and CNC processing technology and production. Product design is not only graphic design, but also includes CNC processing technology design and production design. Production design should be mainly studied from the following aspects:

A. simplify the function or shape of parts;

B. maximize the standardization, generalization and serialization of products;

C. make the material grade, variety and specification specified in the design drawings consistent with the use of existing materials as far as possible;

D. combining the CNC machining process of computer gong with CNC machining process of computer gong more effectively;

E according to the CNC processing technology, operation rules and relevant information of the current normal production of the enterprise to judge the rationality of CNC processing technology design of the computer gong;

F select the dimension tolerance and surface roughness that can be guaranteed by mature CNC processing technology;

G comprehensive analysis of information related to the production process, the main parts of the necessary value engineering analysis.

Application of CNC five axis computer gong processing

Five axis machining is a kind of machining center with high technology content and high precision, which is specially used for machining complex curved surface. This machining center system of five axis machining has a great influence on a country’s aviation, aerospace, military, scientific research, precision instruments, high-precision medical equipment and other industries. At present, five axis CNC machining center system is the only way to solve the problems of impeller, blade, marine propeller, heavy generator rotor, steam turbine rotor, large diesel engine crankshaft and so on.

It is a difficult point for five axis parts to process multi-dimensional surface parts. In addition to the application of multi axis machine tool, multi axis programming technology is the key. Reasonable setting of machining tool path is an important guarantee for the surface accuracy and dimensional accuracy of parts. Five axis parts processing taking human head image processing as an example, this paper discusses and analyzes the practical application of five axis cutting to multi-dimensional surface parts processing.

Five axis parts processing has the characteristics of high efficiency and high precision, the workpiece can complete complex processing with one clamping. It can adapt to the processing of modern molds such as auto parts and aircraft structural parts. There is a big difference between five axis machining center and pentahedron machining center. Many people don’t know the five axis machining, and mistakenly regard the pentahedron machining center as the five axis machining center. Five axis machining center has x, y, Z, a, C five axis, XYZ and AC axis form five axis linkage processing, good at space surface processing, special processing, hollow processing, drilling, oblique hole, oblique cutting and so on. Five axis parts processing and “pentahedron machining center” is similar to the three-axis machining center, but it can do five faces at the same time, but it can’t do special-shaped processing, oblique hole, cutting slope, etc.

A five axis machining type for mechanical parts relates to a five axis manipulator. Its main features are that the shoulder mechanism and the reducer shaft of the waist mechanism fixed on the fixed seat are fixedly installed to realize the radial swing of the shoulder mechanism and the reducer shaft of the fixed seat, the elbow mechanism and wrist mechanism for five axis mechanical parts processing realize the relative swing between the shoulder mechanism and the elbow mechanism, and the elbow mechanism and wrist mechanism respectively, and the five axis mechanical parts processing claw mechanism is installed on the bevel gear shaft of the wrist mechanism and passes through A pair of gears installed on the wrist mechanism reducer are meshed with the bevel gears of the claw mechanism.

Five axis machine parts processing type has simple structure, comprehensive functions, good reliability, stability and accuracy of the whole machine. It can perfectly replace the existing manipulator, and is suitable for welding, assembly, processing and other industrial systems. Five axis mechanical parts processing CS Series manipulator is suitable for 500 ~ 3000 tons of various types of horizontal injection molding machine products and nozzle extraction. The upper and lower arm type is variable section type; the up and down stroke is 800 ~ 3000mm, and the X, y, Z three axes are driven by AC servo motor. The installation can increase the production capacity (20 ~ 30%), reduce the defective rate of products, ensure the safety of operators, reduce labor, accurately control the production volume, and reduce waste.

The five axis mechanical parts processing is driven by drive components such as motor, reducer, pulley mechanism, sprocket mechanism, etc. it is characterized in that: the manipulator includes waist mechanism, shoulder mechanism, elbow mechanism, wrist mechanism and claw mechanism. The five axis mechanical parts processing shoulder mechanism and the reducer shaft of waist mechanism fixed on the fixed seat are fixed together The elbow mechanism and wrist mechanism are respectively installed in the shoulder mechanism and the reducer in the elbow mechanism to realize the relative swing between the shoulder mechanism and the elbow mechanism, and between the elbow mechanism and the wrist mechanism. The five axis mechanical parts processing claw mechanism is installed on the bevel gear shaft of the wrist mechanism, and is installed on the reducer of the wrist mechanism The engagement of a pair of bevel gears with the claw mechanism realizes the swing or rotation of the claw mechanism.

Five axis impeller machining supports four axis roughening, and some manual settings can be made in the control of the axis. Of course, in the process of generating the program, automatic avoidance can adjust these parameters. Channel finishing method is mainly used to finish the channel surface of five axis impeller. Various finishing strategies provide different optimization path distribution and tool inclination calculation methods for tasks. Similarly, the five axis impeller machining also supports the four axis mentioned above and the manual setting of tool tilting and other functions.

Five axis impeller machining point is to use the tool point contact method to process the blade surface with continuous and spiral circular action. In this method, a variety of machining modes and feeding strategies are provided to adapt to different tasks, such as the cavity mode of five axis impeller machining to reduce the vibration of adjacent blades. The strategy also supports the four axis and manual tool tilting functions mentioned above.

Five axis impeller machining is a kind of typical free-form surface parts. If the traditional cam machining strategy is adopted, different machining directions need to be tested repeatedly, and the paths of different directions need to be connected through human intervention, which will take a lot of time to adjust. Traditional machining methods are time-consuming and difficult to ensure accuracy. HyperMILL? Provides professional machining modules for both open and closed five axis impeller machining, so that even users with less experience in machining can program NC programs of this kind of parts which are difficult to complete by using conventional programming strategy in a short time through simple settings. This specialized module is commonly used in various fields of five axis impeller processing.

Basic knowledge of CNC lathe

Numerical control (NC) technology refers to the use of digital instructions composed of numbers, words and symbols to realize the action control of one or more mechanical equipment. Numerical control generally uses general or special purpose computer to realize digital program control, so numerical control is also called computer numerical control, referred to as CNC, foreign countries are generally called CNC, rarely use the concept of NC.

It usually controls mechanical quantities such as position, angle and speed, as well as switching quantities related to the flow direction of mechanical energy. The generation of numerical control depends on the appearance of data carrier and binary data operation. In 1908, the perforated sheet metal interchangeable data carrier came out; at the end of the 19th century, the control system with paper as the data carrier and auxiliary functions was invented; in 1938, Shannon carried out rapid data calculation and transmission at the Massachusetts Institute of technology, laying the foundation of modern computer, including computer digital control system. Numerical control technology is closely combined with machine tool control. In 1952, the first CNC machine tool came out, which became an epoch-making event in the history of world machinery industry and promoted the development of automation.

Now, the numerical control technology is also called the computer numerical control technology (CNC), at present it is using the computer to realize the digital program control technology. In this technology, the computer can control the movement track of the equipment and the operation sequence logic of the peripheral equipment according to the control program stored in advance. Because the numerical control device composed of hardware logic circuit is replaced by computer, all kinds of control functions such as storage, processing, operation and logic judgment of input operation instructions can be realized by computer software, and the micro instructions generated by processing are transmitted to the servo driving device to drive the motor or hydraulic actuator to drive the equipment.

Numerical control technology is the technology that uses digital information to control the mechanical movement and working process. Numerical control equipment is the mechatronics product formed by the penetration of new technology represented by numerical control technology into traditional manufacturing industry and emerging manufacturing industry, namely the so-called digital equipment, such as numerical control machine tools. Its technology involves many fields

(1) Mechanical manufacturing technology;

(2) Information processing, processing and transmission technology;

(3) Automatic control technology;

(4) Servo drive technology;

(5) Sensor technology;

(6) Software technology, etc.

Numerical control technology and equipment is the enabling technology and the most basic equipment for the development of new high-tech industries and cutting-edge industries. CNC technology is widely used in information industry, biological industry, aviation, aerospace and other national defense industries all over the world in order to improve manufacturing capacity and level, and improve market adaptability and competitiveness. Industrial developed countries also list CNC technology and CNC equipment as national strategic materials, not only vigorously develop their own CNC technology and industry, but also implement blockade and restriction policies on China’s “high-end” CNC key technology and equipment. Therefore, it has become an important way for developed countries in the world to develop advanced manufacturing technology with numerical control technology as the core to accelerate economic development and improve comprehensive national strength and national status.

Positioning principle of CNC five axis machining

  1. Five axis vibration disc machining center, also known as five axis linkage machining center, is a kind of machining center with high technology content and high precision, which is specially used for machining complex surfaces.
  2. This kind of machining center system has a decisive influence on a country’s aviation, aerospace, military, scientific research, precision equipment, high-precision medical equipment and other industries.
  3. The five axis machining center has the characteristics of high efficiency and high precision. The complex machining can be completed by clamping the workpiece once. There is a big difference between five axis machining center and pentahedron machining center. Many people don’t know this and mistakenly regard pentahedral machining center as five axis machining center.

The common linear feeder consists of three parts: linear track, electromagnet and spring. By connecting the electromagnet with 220 V AC, the electromagnet vibrates, and the electromagnet drives the linear track movement through the spring plate, so as to achieve the purpose of linear feeding.

Five axis vibration disk processing application field:

Linear feeder is widely used in many fields. Generally speaking, as long as the need for vibration plate feeding place, you need a linear feeder for linear feeding!

Working principle of five axis vibration disk machining:

The practical application of five axis vibration disk machining shows that the reasonable AC servo system can meet the requirements of fast response speed, high speed accuracy and strong robustness of the control system, and the maximum position control accuracy in practical application is about ± 0.1 mm, and the accumulated error can be avoided. The control system can be used in the production of high-precision opening series cold-formed steel products, especially the products similar to shelf column, that is, the cold-formed forming production line with on-line pre punching holes with high-precision requirements for the vertical and lateral positions of cold-formed steel.

In fact, the application of five axis machining in mass production is increasing. Some parts do need five axis machining, while some parts do not need five axis machining at all. The increase of this kind of application is due to the more and more complex parts and the higher precision requirements of parts. This kind of parts is the representative of the vast majority of five axis machining. In this case, it has the advantage of one-time clamping to complete all the processing. The reason for using five axis machining is that it can improve the processing capacity and production efficiency.

Most practical five axis machine tools are composed of three linear coordinate axes and two rotary axes. In addition, it has been proved that the 3 + 2 axis part positioning (trunnion and planetary structure) with three linear axes and two rotary axes on one side of the tool is a good solution.

Another innovative variant design of five axis vibration disc machining is that three linear axes and one rotary axis are used on one side of the tool, and the workpiece is driven by only one rotary axis (tilt head frame structure). These two structures will be further discussed in the following. All the five axis motion is completed by one side of the tool, and the work is not only a common structure in the processing of large parts such as aircraft and large mold. This is because the size and mass of the parts are too large to adopt other structures. The recently developed parallel kinematic machine tool is also entering industrial application. UG / post execute and UG / post builder constitute the post-processing of UG processing module. The postprocessing module of UG makes it easy for users to set up their own postprocessing program. The two basic elements of post-processing are tool path data and a postprocessor.

There are two ways to use UG / post execute postprocessor for postprocessing

① Using mom (manufacturing output manager), the,

② Using GPM (graphics postprocessor module).

The working process of mom is as follows:

Tool path source file → postprocessor → NC machine tool

Mom post-processing takes UG tool path as input. It needs two files: one is event handler with extension. TCL, which contains a series of instructions to handle different event types; the other is definition file with extension. Def, which contains a series of static information of machine tools and tools. These two files can be generated by UG’s own tool post builder. When these two files are generated, they should be added to the template_ post.dat The format is as follows:

fanuc,${UGII_ CAM_ POST_ DIR} fanuc.tcl ,${UGII_ CAM_ POST_ DIR} fanuc.def .

Processing technology identification of computer gong

By analyzing the process of the workpiece structure, the uniform geometry type and size should be adopted as far as possible for the inner cavity and shape of the workpiece. “For example, the width of the shoulder undercut with the same diameter on the same shaft should be as uniform as possible, so as to reduce the size of the tool and the number of tool changes, facilitate programming and improve the processing efficiency of CNC machine tools.”

The radius of the transition fillet between the inner groove and the edge plate of the workpiece should not be too small: “the radius of the transition fillet reflects the size of the tool diameter, and the ratio of the tool diameter to the depth of the contour of the workpiece to be machined is related to the stiffness of the tool”.

The fillet radius at the bottom of the groove should not be too large: “when milling the bottom of the workpiece, the larger the fillet radius r at the bottom of the groove, the worse the milling ability of the end edge of the milling cutter. The maximum diameter of the milling cutter in contact with the milling plane D = d-2r (D is the diameter of the milling cutter). When D is fixed, the larger R is, the smaller the area of the milling plane of the end edge of the milling cutter is, and the surface processing ability is correspondingly reduced.”

This paper analyzes the reliability of the part positioning datum: “the unified datum positioning should be adopted as far as possible in NC machining, otherwise the position error and shape error of the workpiece processing will be caused by the installation and positioning error of the workpiece.”

If it is necessary to turn the workpiece on the CNC machine tool, it is better to select the machined outer circle or the machined inner hole as the positioning reference. If not, the auxiliary datum should be set. If necessary, the process boss or process hole should be added to the blank, and the auxiliary datum should be processed after processing.

The main component of the machine body is the casting, which is also a major factor affecting the accuracy of the computer gong machine. It can even be said that the quality of the casting determines the grade of the machine tool and the stability of its future use. What are the requirements for large gantry computer gongs to process castings? They are not deformed and rigid enough. In this way, both casting and product technology are very perfect.

Machining accuracy refers to the degree of conformity between the actual geometric number (size, shape and position) and the ideal geometric parameters. It is impossible for the actual machining to be completely consistent with the ideal part, and there will always be different deviations. The deviation degree of the actual geometric parameters after machining from the ideal geometric parameters is called machining error. These machining errors often appear in the “large-scale machining process”, so how to complete the machining accuracy? The details are as follows:

Processing economic precision

Because there are many factors affecting the machining accuracy in the machining process, the same machining method can achieve different accuracy under different working conditions. Any kind of processing method, as long as the careful operation, careful adjustment, and the selection of appropriate cutting parameters for processing, can make the machining accuracy greatly improved, but will reduce the productivity, increase the processing cost. The processing error delta is inversely proportional to the processing cost C. The processing economic precision of a certain processing method should not be understood as a certain value, but as a range, which can be said to be economic.

Original error

There are all kinds of errors in the machining process system composed of machine tool, fixture, cutter and workpiece. These errors will be reflected as the machining errors of workpiece in different ways (or expanding or shrinking) under different working conditions.

The original errors of process system mainly include geometric error, positioning error, processing error caused by force deformation, processing error caused by heat deformation, deformation caused by redistribution of internal stress, principle error, adjustment error, measurement error, etc.

2、 Set error of process system

  1. Geometric error of machine tool

In machining, the forming movement of the tool relative to the workpiece is generally completed by the machine tool. Therefore, the machining accuracy of the workpiece depends on the accuracy of the machine tool to a great extent. The manufacturing errors of machine tools have great influence on the machining accuracy of workpieces: spindle rotation error, guide rail error and transmission chain error. The wear and tear of the machine tool will reduce the working accuracy of the machine tool.

Spindle rotation error

The spindle of machine tool is the datum for clamping the workpiece or cutter, and transmits the motion and power to the workpiece or cutter. The rotation error of spindle will directly affect the accuracy of the workpiece to be processed.

The spindle rotation error refers to the variation of the actual rotation axis of the spindle at each instant relative to its average rotation axis. It can be divided into three basic forms: radial circular runout, axial movement and angular swing.

The main reasons for the radial rotation error of the spindle are: the coaxiality error of several sections of the Journal of the spindle, various errors of the bearing itself, coaxiality error between the bearings, spindle winding, etc. But their influence on the radial rotation accuracy of the spindle varies with different machining methods.

The main reason for the axial movement is the verticality error between the end face of the spindle shoulder and the bearing end face of the spindle rotation axis.

In the process of large-scale machining, the machining error caused by spindle rotation error is different with different machining methods. When machining outer circle and inner hole on lathe, the radial rotation error of spindle can cause roundness and cylindricity error of workpiece, but it has no direct effect on the end face of workpiece. The axial rotation error of the spindle has little influence on the machining of outer circle and inner hole, but has great influence on the perpendicularity and flatness of the machined end face. When turning the thread, the spindle rotation error can make the lead of the processed thread produce periodic error.

The most difficult material for computer gong

  1. Benchmark first

Parts processing generally starts from the processing of precision datum, and then processes other surfaces with precision datum. Therefore, the surface selected as the precision reference should be processed first in the initial process of the process, so as to provide the precision reference for the subsequent process. For example, for shaft parts, first process the center hole at both ends, and then use the center hole as the precision benchmark to rough and finish all the cylindrical surfaces. In gear machining, the inner hole and the reference end face are machined first, and then the inner hole and the end face are used as the fine reference to rough and finish the tooth surface.

  1. First coarse, then fine

After finishing, the machining of the whole part should be the roughing process, followed by semi finishing, finishing and finishing. According to the principle of roughing before finishing, the main surfaces with high precision are machined first, that is, roughing first, then semi finishing, and finally finishing and finishing. Before finishing the important surface, sometimes it is necessary to trim the precision datum to ensure the machining accuracy of the important surface. For example, in the high-precision grinding of the spindle, the center hole must be ground before finishing and superfinishing; in the precision gear grinding, the inner hole must also be ground.

  1. First, first, then

According to the function and technical requirements of the parts. First, separate the main surface and the secondary surface of the part, then arrange the processing of the main surface first, and then insert the processing procedure of the secondary surface into it. Secondary surface generally refers to keyway, screw hole, pin hole and other surfaces. These surfaces generally have certain relative position requirements with the main surface, so the secondary surface processing should be based on the main surface, so the secondary surface processing is generally placed after the semi finishing of the main surface, and the primary processing is finished before finishing. Some are placed in the final processing, but at this time should be careful not to damage the main surface has been processed.

  1. Face before hole

For the box, base, bracket and other parts, the plane contour size is larger, and it is more stable and reliable to use it as the precision datum to process the hole, and it is also easy to process, which is conducive to ensuring the accuracy of the hole. If the hole is machined first, and then the plane is machined based on the hole, it will be more difficult, and the machining quality will also be affected.

In the production process of compressor parts, we often come into contact with some difficult to process materials. For example, the material for manufacturing compressor impeller is a kind of high-strength structural steel containing Cr, Ni, Mo and other alloy elements. Once the steel reaches a certain hardness after quenching and tempering, it is difficult to turn. Because of the existence of Qinzhou alloy elements, Qinzhou alloy impeller brings a lot of trouble to turning. The process of carburizing and quenching of large hardened gears will cause some hard surfaces to be machined, which are difficult to turn. There are also some sets of parts made of pure metal, such as copper, which are commonly used in transportation machinery, also bring considerable trouble to turning. In order to solve the turning problems of these difficult to machine materials, we need to have a sufficient understanding of the characteristics of difficult to machine materials, and then take targeted measures to solve them.

What is difficult to process material

The so-called difficult to machine materials mainly refer to the materials with poor cutting performance. The machinability of metal materials is mainly measured from three aspects: the tool life, the quality of machined surface and the difficulty of chip formation and removal. As long as there is an obvious difference in the above three aspects, it can be considered as difficult to process materials. The common difficult to process materials are high strength steel and stainless steel

Turning temperature: when cutting hard to machine materials, the cutting temperature is generally high. The main reasons are as follows.

Low thermal conductivity: the thermal conductivity of difficult to machine materials is generally low (except for pure metal copper, etc.), the cutting heat is not easy to spread during cutting, and it is easy to concentrate on the tool tip.

High thermal strength: the tensile strength of superalloys such as nickel base alloy reaches the highest value at 500-800 ℃. Therefore, when turning this kind of alloy, the turning speed of the turning tool should not be too high, generally not more than 10m / min, otherwise the cutting resistance of the tool cutting into the workpiece will increase.

Cutting deformation coefficient and work hardening: high temperature alloy and stainless steel in difficult to machine materials, the deformation coefficient of these materials are relatively large. When the cutting speed is about 6 m / min, the chip deformation coefficient will reach the maximum value. Because of the plastic deformation of the chip formed in the turning process, the metal hardens and strengthens, which increases the cutting resistance, speeds up the tool wear, and even leads to edge collapse. For example, the austenitic structure of high temperature alloy, high manganese steel and austenitic stainless steel has a great degree of hardening and depth, which is several times larger than that of 45 steel. Due to severe hardening, high temperature and hardness of chips, good toughness and high cutting temperature (strong and tough chips), if such chips flow through the rake face, it is easy to produce sticking phenomenon such as bonding and fusion welding. Sticking is not conducive to the removal of chips, so that the chip grains are blocked and it is easy to cause cutting. It is also easy to cause the tool to wear and crack. In addition, the tough chip is serrated, which is easy to damage the cutting edge.

CNC computer gong machine precision debugging

The high-speed computer gong uses the precision level instrument and other testing tools, mainly through adjusting the pad iron 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;

For the automatic tool changing device, adjust the position of tool magazine, manipulator, stroke parameters, etc., and then check the action with instructions to ensure accuracy;

For the machine tool with APC automatic exchange table, after adjusting the relative position, carry out automatic exchange;

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, and the execution of common instructions.

High speed computer gong to check the normal operation of auxiliary functions and accessories of the machine tool. It is usually composed of numerical control system, main drive system, feed servo system and cooling system

  1. The spindle box includes the spindle box and the spindle drive system, which is used for clamping the tool and driving the tool to rotate. The spindle speed scale and output torque have a direct impact on the processing.
  2. The feed servo system is composed of feed motor and feed performing mechanism. According to the feed speed set by the program, the relative motion between the tool and the workpiece is completed, including linear feed motion and rotary motion.
  3. The control system is the middle of the motion control of CNC milling machine, which performs the CNC processing program to control the machine tool for processing.
  4. Auxiliary equipment such as hydraulic, pneumatic, smooth, cooling system and chip removal, protection equipment.
  5. The basic parts of high-speed computer gong machine tool usually refer to the base, column, beam, etc., which is the foundation and structure of the whole machine tool. High speed Gong processing economical CNC lathe is also known as simple CNC machine tool. Its main characteristics are low price and strong function pertinence. In general, after refitting ordinary machine tools into economical CNC 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.

High speed Gong machining generally uses a single board microcomputer as the control device and a stepping motor as the actuator to transform the ordinary machine tool into an economic CNC lathe. The reformed machine tool not only retains the generality of the original machine tool, but also adds many features that the traditional machine tool does not have, such as automatic tool setting, clearance compensation, automatic feed speed adjustment, automatic return to origin and so on. This kind of machine tool is especially suitable for frequent and rotational machining of rod, shaft, disc parts and parts with taper and spherical surface of medium complexity.

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

  1. Open loop system driven by stepper motor. This kind of system is widely used. Economical CNC lathe can complete the processing of cylinder, plane, cone, curved surface and thread.
  2. It is a point position numerical control system driven by asynchronous motor or DC motor and fed back by grating measurement.
  3. A semi closed loop system driven by DC servo motor for high speed Gong machining. Because of the high price, this kind of system is mainly used for new machine tools.

Modern control technology of large computer gong processing machine Large scale CNC machine tools combine the rapidity of modern control technology with the precision of machine tool movement, forming a real constant speed processing system. The control system of CNC machine tools may become an obstacle to shorten the processing cycle and improve the finish of complex 3D models, aerospace parts or medical devices. When the processor can’t keep up with the running speed of the program, the driver will reduce the feed speed of the tool due to the urgent need of information, thus prolonging the processing cycle and leading to the uncoordinated operation of the tool. In order to replace the worn and overloaded tools, in addition to increasing the number of tool runs to the tool library, it will also affect the effective utilization of the spindle, increase the workload of fitter and finishing time.

Large computer gong processing when the speed (feed rate) is not stable, there will be some problems. When the cutting tool runs through the part processing, its uneven movement will cause different loads on the cutting groove of the cutting tool, thus affecting the machining accuracy and surface finish. If the running speed of the tool is not fast enough to maintain the minimum cutting load of the tool, friction will occur between the tool and the workpiece instead of cutting, then the unstable movement of the tool will shorten the service life of the tool. This operation mode will also cause a small amount of fracture gap of the blade, which will make the tool hot and blunt. However, with constant speed processing, the average processing speed of the tool through the workpiece will be more uniform, and the processing accuracy will be higher, which can not only shorten the processing time, but also extend the service life of the tool.

In the process of program execution of large-scale computer gong processing, the result of high-speed program processing is that the random error of the control system can be stably monitored and adjusted, so that the tool can run at a uniform speed and achieve a perfect surface integrity. The system uses more than 80 high-speed buffers to monitor the operation of the cutting tool. If the random error is exceeded, the movement of the cutting tool can be adjusted immediately

Classification of CNC computer gong processing technology

  1. Processing technology

The so-called technology is the problem of how to process and how to process. When we are familiar with the cutting ability of cutting tools to materials, the computer gong processing factory understands that the software can control, and then the problem of how to cut is good. For example, if you want to cut (process) a plane or a corner of a mold (part), how to make it more smooth, whether it will touch the fillet at the bottom, whether it is beautiful to process, whether it will have allowance, and so on.

  1. Metal cutting

To know the characteristics of cutting tools on materials, heating, overload, speed, cutting depth of each layer, skills are required: metal materials, cutting tool materials and types, cutting ability of cutting tools on metal, mechanical analysis, you can find some books on this, there are many bookstores. You need to know what kind of speed this knife should give to cut this metal material. How many millimeters can you run per minute, and how deep can you process each layer.

  1. Control part

This part is a pure software problem, how to cut, think well, analyze thoroughly, we need software to control, produce the desired cutting mode. After selecting the surface or solid to be machined, many values are set in turn, such as depth control, processing from Z height to height, processing depth of each layer, how to lift the tool between layers, processing range control, etc.