July 2019 – Page 21 – CNC Machining & Turning, Milling, Metal parts

Power head and tool changing mechanism of CNC machining center

With the continuous development of science and technology, the quality and productivity of mechanical products are increasingly demanded, all of which rely on the further improvement of mechanical and technological. Automation of machining process is one of the most important measures to achieve the above requirements. The so-called machining is to process metal blank parts into the desired shape, including two aspects of dimensional accuracy and geometric accuracy. Can complete the above functions of the equipment are called machine tools, CNC machine tools is the development of ordinary machine tools, CNC means digital control. After the CNC system is installed on the machine tool, the machine tool becomes a numerical control machine tool. Digital control machine tool refers to the information in the form of digital code (program instructions), control tool according to a given working procedure, speed and locus for automatic machining machine tools. Generally speaking, CNC equipment mainly refers to CNC machine tools and machining centers. NC machining center is a highly integrated Mechatronics product. It adds tool depot and automatic tool changer to the original NC machine tool. It makes full use of the continuous development of computer control technology and other and many advanced precision machinery and automatic control systems.

machining center

In 1948, Parsons Corp. of the United States accepted the Commission of the United States Air Force, the development of aircraft propeller blade profile template processing equipment. Because of the complex shape and high precision of the prototype, it is difficult for the general processing equipment to adapt, so the idea of computer control machine tool is put forward. In 1949, with the assistance of the MIT Servo Research Laboratory, the company began to study CNC machine tools. In 1952, it successfully developed the first three-axis CNC milling machine modified from a large vertical profiling milling machine. It soon began production and was officially put into use in 1957. This is a major breakthrough in the development of manufacturing technology, marking the beginning of the era of NC machining in the manufacturing field. NC machining is the foundation of modern manufacturing technology. This invention has epoch-making significance and far-reaching impact on the manufacturing industry.

Vertical machining center

During the Eleventh Five-Year Plan period, with the breakthrough of a series of key technologies and the formation of independent production capacity, China began to highlight the “heavy encirclement” of “foreign-made” and entered the ranks of the world’s high-speed CNC machine tools and high-precision CNC machine tools producers. Under the pull of demand, the output of CNC machine tools in China maintained a high-speed growth, with an annual compound growth rate of 37.4%. In 2010, China’s CNC machine tool output reached 236,000, an increase of 62.2%; in 2010, China’s CNC machine tool consumption exceeded 6 billion U.S. dollars, more than 100,000 sets, CNC machine tools have become the mainstream of machine tool consumption. Since 2009, the continuous investment in the major scientific and technological projects of “high-grade CNC machine tools and basic manufacturing equipment” shows the government’s determination to develop high-grade CNC machine tools and basic manufacturing equipment. During the Twelfth Five-Year Plan period, China will continue to invest, and increase its efforts. Major special projects will lead to investment of more than 10 billion yuan annually.

Small CNC milling machine

Looking forward to the 12th Five-Year Plan, the development of China’s CNC machine tools will strive to solve the problems of large but not strong mainframe, lagging development of CNC systems and functional components, large gap in key technologies of high-grade CNC machine tools, low product quality stability, poor overall economic benefits of the industry and so on, and will cultivate core competitiveness, independent innovation, quantitative integration. And brand building to a strategic height, achieving the target of 800 billion yuan of total industrial output value. We will strive to achieve a series of medium and long-term goals, such as the transformation from a big machine tool producer to a powerful machine tool producer, and the realization of the dominant position of domestic medium and high-grade CNC machine tools in the domestic market. The development of computer control technology and other and many advanced precision machinery and automation control system composition.

Is stamping as punch

1. Stamping is a method of forming and processing workpiece (stamping piece) with required shape and size by applying external force to sheet, strip, pipe and profile by press and die. Stamping and forging belong to plastic processing (or pressure machining). The stamping blanks are mainly hot rolled and cold-rolled steel plates and steel strips. 60 to 70% of the steel products in the world are sheets, most of which are stamped into finished products. The car body, chassis, fuel tank, radiator fin, boiler drum, container shell, electrical machinery, electrical core silicon steel sheet, etc. are stamped. Instruments, household appliances, bicycles, office machinery, household utensils and other products, there are also a large number of stamping parts.

Stamping is a kind of production technology that can make the sheet metal be directly deformed and deformed in the die by the power of conventional or special stamping equipment, so as to obtain a certain shape, size and performance of product parts. Sheet metal, mold and equipment are the three elements of stamping process. According to the stamping temperature, it can be divided into hot stamping and cold stamping. The former is suitable for sheet metal processing with high deformation resistance and poor plasticity, while the latter is carried out at room temperature, which is a common stamping method for sheet metal. It is one of the main methods of metal plastic processing (or pressure processing), also belongs to the material forming engineering technology.

The die used for stamping is called stamping die, or die. Punching die is a special tool for batch processing material (metal or non-metal) into the required stamping parts. The punching die is very important in stamping. Without the punching die that meets the requirements, the batch stamping production will be difficult; without the advanced punching die, the advanced stamping process will not be realized. Stamping process and die, stamping equipment and stamping materials constitute the three elements of stamping processing, and only when they are combined can stamping parts be obtained.

2, punch press is a punch press. In the national production, stamping process is more and more widely used because it has the advantages of saving materials and energy, high efficiency, low technical requirements for operators and can make products that can not be achieved by machining through various die applications.

Stamping production is mainly aimed at sheet metal. Through the mold, can be blanking, punching, forming, drawing, dressing, fine punching, shaping, riveting and extrusion parts, and so on, widely used in various fields. For example, we use switches and sockets, cups, cupboards, saucers, computer boxes, even missile planes. There are a lot of accessories that can be produced by punching machines through molds.

Industry characteristics of machinery industry

From the analysis of the situation of the machinery industry, the growth rate of hand-held orders is not low, it is not expected that there will be a big ups and downs in production problems. In the second half of this year, the economic operation of machinery industry continued to grow steadily. Total industrial output value, industrial added value, main business income, total profit and foreign trade export volume will maintain a relatively high growth rate of about 25%.

Starting from the characteristics of production, we can see that the mechanical manufacturing industry has the main characteristics of discrete-based, process-assisted, assembly-focused. Taking equipment manufacturing as an example, the mode of production is generally composed of individual parts and final products, which is a typical discrete industry. Although the automobile manufacturing industry, such as die casting, surface treatment and other processes belong to the category of process, but most of the process is still characterized by discrete. Based on the above industry characteristics, the machinery industry has the following characteristics in the course of production and operation.

1, the production planning and production tasks management tasks are arduous.

Typical discrete machinery manufacturing enterprises are mainly engaged in single-piece and small-batch production, and the process of products is often changed. It is difficult to predict when the order will arrive because the production is mainly organized according to the order. Therefore, a good production planning system is needed for the purchase and production workshop planning.

2, the level of automation is relatively low.

Because of discrete processing, the quality and productivity of products depend largely on the technical level of workers. Automation is mainly at the unit level, such as CNC machine tools, flexible manufacturing systems and so on.

3, the process is simple and clear, the process is flexible, and the coordination of manufacturing resources is difficult.

The product structure of machinery industry is clear and definite. The product structure of a mechanical manufacturing enterprise can be described by the concept of number. The final product must be composed of fixed number of parts or components. These relations are very clear and fixed. Order oriented machinery manufacturing industry is characterized by multiple varieties and small batch. Therefore, the layout of production equipment in the machinery manufacturing industry is generally not according to the product but according to the process, the process of each product may be different, and there are more than one machine tool that can carry out the same processing technology. Therefore, it is necessary to schedule the processed materials, and intermediate goods need to be transported.

Hardware application

Auxiliary, accessory finished products used in daily life and industrial production. In the early days, it was made of metal materials such as gold, silver, copper, iron and tin, hence the name.
Hardware
In addition to the use of various metal materials, it is also widely used in non-metallic materials such as plastics and glass fibers. Hardware products have played an important role in the survival and development of human beings. With the development of social economy and the refinement of social division of labor, hardware products are gradually enriched and improved, and more and more varieties. Modern hardware products can be divided into three categories according to their purposes: daily hardware for daily life, hand tools for production and living aids, construction of joints, fasteners and supporting facilities in buildings and structures. Hardware. Metal materials are generally made by forging blanks, machining, surface treatment and other processes. The purpose of surface treatment is to prevent corrosion and aesthetics. Non-metallic materials are mostly molded or pressure molded, which is light and convenient.

Fan classification method

Fans can be divided into several types according to the material used, such as iron shell fan (common fan), fiberglass fan, plastic fan, aluminum fan, stainless steel fan and so on.

According to the direction of gas flow

Fan classification can be divided into centrifugal, axial, diagonal (mixed flow) and cross flow according to the direction of gas flow.

(1) Centrifugal fan. The airflow mainly flows in the radial direction after entering the impeller of the fan axially. These fans are made according to the principle of centrifugal action, and the products include centrifugal fans, centrifugal blowers and centrifugal compressors.

(2) Axial fan. The airflow enters the impeller of the fan axially, flowing approximately in the axial direction on the cylindrical surface. Such fans include axial flow fans, axial flow blowers and axial compressors.

(3) Rotary fan. The rotor chamber is rotated to change the volume of the chamber to operate. Common varieties are Roots blowers and rotary compressors.

The fan is divided into an axial flow fan, a centrifugal fan and a diagonal flow (mixed flow) fan according to the flow direction of the airflow after entering the impeller.

The fan is divided into a push-in type local fan (hereinafter referred to as a press-in fan) and an explosion-proof motor placed outside the flow channel or in the flow channel according to the purpose, and the explosion-proof motor is placed in the explosion-proof sealed cavity of the extracting type local fan (hereinafter referred to as the extracting fan) ).

The fan can also be divided into single-stage, two-stage or multi-stage pressure fans according to the form of pressure. For example, 4-72 is a single-stage pressurization, and a high-end fan is a multi-stage pressurized fan. cnc machining

Fans can be divided into: axial flow fans, mixed flow fans, roof fans, air conditioning fans, etc. according to the purpose.

The fan can be divided into a negative pressure fan, a low pressure fan, a medium pressure fan and a high pressure fan according to the pressure.

According to the outlet pressure (boost), it is divided into: fan (≤ 15,000 Pa), blower (1.5 to 350,000 Pa), compressor (≥ 350,000 Pa).

Sort by layer

There are many classification methods for ventilators, which can be roughly classified by the following types:

(1) According to the level of pressure generated, it can be divided into: volumetric type: reciprocating type and rotary type; turbine type: centrifugal type, axial flow type, mixed flow type and cross flow type, and jet type.

Fans generally refer to turbine type, ie, centrifugal, axial, mixed flow, cross flow, and the like.

Its main features are:

Centrifugal fan: higher pressure, but less air.

Axial fan: Higher air volume, but lower pressure.

Mixed flow fan: The air volume and pressure are between the centrifugal and axial fans.

Cross-flow fan: It has a high dynamic pressure and can get a flat air flow.

(2) According to the different materials used, it can be divided into: iron shell fan (common fan), fiberglass fan, plastic fan, aluminum fan, stainless steel fan, etc.

(3) According to the direction of gas flow, it can be divided into centrifugal type, axial flow type, diagonal flow type (mixed flow type) and cross flow type.

(4) The flow direction after entering the impeller according to the airflow can be divided into: axial flow fan, centrifugal fan and diagonal flow (mixed flow) fan.

(5) According to the application, it can be divided into: the push-in partial fan and the explosion-proof motor are placed outside the flow channel or in the flow channel, and the explosion-proof motor is placed in the explosion-proof sealed cavity.

(6) It can also be divided according to the form of pressurization: single-stage, double-stage or multi-stage pressurized fan.

Fan performance parameters

The performance parameters of the fan mainly include flow, pressure, power, efficiency and speed.

In addition, the size of noise and vibration is also the main fan design indicator. The flow rate is also called the air volume, which is expressed by the volume of gas flowing through the fan per unit time. The pressure is also called the wind pressure. It refers to the pressure rise of the gas in the fan, and there are static pressure, dynamic pressure and full pressure. The power refers to the fan. Input power, ie shaft power. The ratio of the effective power of the fan to the shaft power is called efficiency. The total pressure efficiency of the fan can reach 90%.

Safety operation rules for CNC turret punch press

CNC turret punch safety operation procedures:

1. The CNC turret punch operator must undergo professional learning and training to master the structure and performance of the numerical control equipment, familiar with the operating procedures and obtain the operation permission before operating independently.
2. Correctly use the safety protection and control devices on the numerical control equipment, and do not arbitrarily disassemble them.
3. Check whether the transmission, connection, lubrication and other parts of the CNC turret punching machine and the protective safety device are normal. The mold screws must be confirmed whether they are firm or not.
4. The CNC turret punch press should be emptied for 2-3 minutes before work. Check the flexibility of the control device such as the foot brake, and confirm that it can be used after normal operation.
5. When installing the CNC Machining turret mold, it must be tight and firm. The upper and lower molds should be aligned to ensure the correct position. Manually control the CNC turret punch press test (empty car) to ensure that the mold is working under good conditions. 6. Pay attention to lubrication before driving, and remove all floating items on the bed.
7. When the CNC turret punch press starts or runs, the operator should stand properly, the hand and head should be kept at a certain distance from the punching machine, and always pay attention to the punch action. It is strictly forbidden to chat with others. 8. When processing special small workpieces, apply special tools, and do not directly feed or take the parts by hand. 9. Stop at the end of the work, cut off the power, wipe the CNC turret punch, and organize the surrounding environment.

Error form in the use of wire cutting machines

The error of the wire cutting machine refers to the difference between the workpiece obtained by the cutting and the expected value at the end of the wire cutting. This gap may come from machine tool accuracy, which may come from material deformation, may be due to calculation errors, or may come from machine control control errors, including:
1. Computational errors: This is the reason for people. It can be checked and proved. It can also be discovered early. The middle calculation is premature rounding, and multiple irrational numbers with insufficient digits (such as multi-tooth shape) are used repeatedly, and the decimal angle system is confused with the degree-minute system.
2, machine control error: the frequency of occurrence is very rare, because today’s machine control system is proven, mature technology. It is rejected by human error, and it can be checked or zeroed before processing. The error homing check accumulated due to multiple rotations can also be found.
3, material deformation: as long as there are good operating habits, the calculation is completed to be rehearsed, after the input is completed to be verified, before the start of the school to zero, the hand wheel scale to check. I am not wrong, the machine tool should not be wrong, there should be sufficient grasp, the rest is deformation, but the reasons for the deformation and the way to overcome must be carefully pondered.
4. Machine tool accuracy: This usually refers to mechanical precision, which is the difference between the actual value and the theoretical value. The most direct cause of this difference is the hysteresis and straightness, verticality. The range of this difference should be within 0.005~0.02mm. This value can be measured and can be adjusted. In today’s machine structure, it is very easy to control this error value below 0. 02. Below 0.005 is very difficult.
In addition, during the use of the online cutting machine, the user also needs to carry out the necessary maintenance and maintenance, among which:
1. Check the switch knob of the circuit system, turn on the AC stabilized power supply, first turn on the power switch, then turn on the high voltage switch, after 5 minutes, connect to the negative line.
2. Check the output data of the regulated power supply and whether the digital tube of the xenon lamp is normal. Enter the information for about 5 minutes and perform the trial operation. Normally, it can be processed.
3, wire cutting high-frequency power switch should be placed in the off position before processing, in the case of molybdenum wire operation, can open high-frequency power, and should be maintained at 60 ~ 80 volts. The high frequency power supply should be turned off before parking.
4. When cutting, add coolant. When the molybdenum wire contacts the workpiece, check whether the voltage and electro-hydraulic value of the high-frequency power supply are normal, and do not process it under the condition of arcing.
5. It is forbidden to touch the wire or workpiece with your hand or conductor. It is also not allowed to touch the switch or other electrical parts with wet hands.
6. If a fault occurs, the high-frequency power supply should be turned off immediately, and the reason should be analyzed. Other items, especially metal equipment, are not allowed in the electric box.

Precautions after processing CNC Turning Machine

Note on the completion of CNC lathe processing:
1. Remove chips, wipe the machine, and keep the machine and environment clean.
2. Pay attention to check or replace the oil wiper on the machine tool rail damaged by the mill.
3. Check the status of lubricating oil and coolant and add or replace them in time.
4. Turn off the power and main power on the machine’s operation panel in turn.
5. When the machine is turned on, it should follow the principle of zero return (except special requirements), manual, jog and automatic. The operation of the machine tool should follow the principle of low speed, medium speed and high speed first, and the running time of low speed and medium speed should not be less than 2-3 minutes. You can start working when you are sure that there are no abnormalities.
6. It is strictly forbidden to knock, correct and correct the workpiece on the chuck and the tip of the ding. Bi must confirm that the workpiece and the tool are clamped before proceeding to the next step.
7. The operator must stop when he changes tools, workpieces, adjusts the workpiece or leaves the machine while working.

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8. The insurance and an full protection device on the CNC CNC lathe shall not be disassembled and moved by the operator.
9. Before the CNC lathe starts processing, the bi-test must be checked by the program to check whether the used program is similar to the part being processed. After the confirmation is correct, the full protective cover can be managed and the machine can be used for part processing.
10, machine tool accessories and measuring tools, tools should be properly kept, to maintain complete and good, lost or damaged parry compensation.
11. After the training is completed, the machine should be cleaned, kept clean, the tailstock and the carriage are moved to the end of the bed, and the machine power is cut off.

What should I avoid when using a gear pump

The gear pump is suitable for various industries and has a wide range of media. The gear pump has the advantages of firm structure, convenient installation, easy disassembly, simple maintenance, uniform flow rate, slight wear and long service life.
1. During the process of using the gear pump, grease should be added frequently. The grease is more volatile, so it is necessary to pay attention to the replacement, and then keep the bearing clean.
2, in the case of use or use, the electric pump should be placed in a relatively dry, non-corrosive, relatively clean environment;
3. The gear pump should be inspected and repaired frequently during the use. It should be checked to check the electric oil drum inside to check the power cord inside; whether the inner wiring, plug and switch can be used normally; whether the bearing parts are damaged or not Places and so on;
4. Each component on the gear pump should be stored. During the process of dismantling the gear pump, each component should be kept and kept clean;

Key points of CNC Machining

Key points of CNC lathe processing

The development of modern manufacturing technology and the wide use of NC machining equipment have greatly promoted the progress of cutting technology. With the need of numerical control and automation in the production process, higher requirements for metal cutting tools are put forward, such as high reliability, high precision, long life, rapid displacement replacement and good chip breaking. It is very important to set reasonable working procedure according to different machining characteristics for realizing highly automatic cutting or unmanned machining. The following is a brief introduction of the process of metal cutting for lathes.

I. reasons for processing stages

(1) To ensure the machining quality, in the roughing stage, because the cutting force and heat produced by the thick metal layer are relatively large, and the clamping force required is also large, the workpiece will produce greater elastic deformation and internal stress, resulting in greater machining errors and greater surface roughness, through semi-finishing. Work and finishing gradually reduce cutting parameters, cutting force and cutting heat, gradually modify the deformation of the workpiece to improve machining accuracy.

(2) High-efficiency equipment with high power and low precision is generally used when rough machining is needed for rational use of machine tools and equipment, and high-precision machine tools are used in finish machining. This not only improves the production efficiency of rough machining, but also prolongs the service life of high precision machine tools and reduces the processing cost.

(3) Easy arrangement of heat treatment process The insertion of heat treatment process naturally divides the machining process into several stages. For example, in precision spindle processing, after rough processing, stress relief aging treatment, after semi-finishing quenching treatment, after finishing cold and low temperature tempering treatment, and finally finishing processing.

(4) The defects of rough workpiece can be found as early as possible after the defects of rough workpiece are discovered in time, and the defects can be repaired or scrapped in time, so as to avoid further processing and increase the loss. Moreover, the finishing stage is arranged at the end, so that the surface after finishing can be protected as far as possible from damage.

Two. Divide the lathe into cutting stage.

That is, the whole process is divided into several stages, so that rough and fine processing can be carried out separately. The machining process of molds can be generally divided into the following stages:
(1) The main task of roughing stage is to remove most of the surface allowance, so that the shape and size of the blank as close as possible to the finished product.

(2) The main task of the semi-finishing stage is to eliminate the errors left by rough machining on the main surface, to prepare necessary precision and allowance for finish CNC machining, and to finish Finishing on the secondary surface, such as drilling, tapping threads, milling keyways, etc.

(3) The main task of the finishing stage is to ensure that the main surfaces meet the technical requirements specified in the drawings.

(4) Finishing process is arranged for surface which requires high dimensional accuracy and surface roughness. The main task of this stage is to improve the dimensional accuracy of the machined surface and reduce the surface roughness, but generally can not correct the shape error and position error.

Three, reasonably divide lathe cutting process.

Two points show that dividing the process into several stages is for the whole process, and can not be judged simply from the processing of a surface or the nature of a process.

(1) Processing of positioning datum of workpiece is always given priority, and it is common, sometimes even necessary, to arrange some rough machining processes such as drilling in finishing stage.

(2) it is not absolute to divide the processing stage. It is not necessary to divide the processing stage for workpiece with good cutting quality, low machining accuracy or small allowance. Some heavy parts with high precision require time-consuming and labor-consuming transportation and installation, and generally do not divide the processing stages, but complete all rough and finish machining tasks under a single clamping.

(3) In order to reduce the influence of clamping deformation on machining accuracy, the clamping mechanism can be loosened after rough machining, and then the workpiece can be re-clamped with a smaller clamping force, which is beneficial to improve the machining accuracy.

Four. Selection of cutting tools

Tool selection is an important part of NC machining process. Cutting tools not only affect the machining efficiency of machine tools, but also directly affect the machining quality of parts. Because the spindle speed and range of NC machine tool is far higher than that of ordinary machine tool, and the output power of spindle is larger, so compared with traditional machining methods, higher requirements are put forward for NC cutting tools, which require high precision, high strength, good rigidity and high durability, and require stable size, installation and adjustment. It’s convenient.

Five. The use of special cutting oil.

Generally, in order to clean the finished product easily, the better viscosity should be determined according to the difficulty of processing and degreasing conditions. Some workpiece raw materials will react with chlorine additives, so we should pay attention to the problem of white rust when choosing cutting oil. The cutting oil containing sulfur and chlorine compound additives can ensure the extreme pressure processing performance, and avoid burrs and cracks on workpiece.