Category Archive Machinery industry

In CNC machine tools, the motorized spindle usually adopts the method of frequency conversion and speed regulation. There are three kinds of control modes: ordinary frequency conversion drive and control, vector control driver drive and control and direct torque control.

Ordinary frequency conversion is scalar drive and control, its drive control characteristic is constant torque drive, output power is proportional to speed. The dynamic performance of ordinary frequency conversion control is not ideal, the control performance is not good at low speed, the output power is not stable enough, and has no c-axis function. But the price is cheap, the structure is simple, and it is used in grinder and ordinary high-speed milling machine. The vector control technology imitates the control of DC motor, orients the rotor magnetic field and realizes the drive and control by vector transformation, which has good dynamic performance. The vector control driver has a large torque value when it is just started. In addition, the motorized spindle has a simple structure and small inertia, so the starting acceleration is large, which can realize the instantaneous allowable limit speed after starting. The latter can realize position and speed feedback, which not only has better dynamic performance, but also can realize c-axis function; while the former has poor dynamic performance and does not have c-axis function, but its price is relatively low.

Direct torque control (DTC) is a new type of High-Performance AC speed regulation technology developed after vector control technology. Its control idea is novel and the system structure is simple and clear. It is more suitable for the drive of high-speed motorized spindle. It can meet the requirements of dynamic and static characteristics of high-speed motorized spindle with high speed, wide speed range and high-speed instantaneous stop. It has become the field of AC drive A hot technology.

Scope of application:

Granite, marble, bluestone, sandstone and other stone carving

Granite and other hard stones can be carved to 5mm in layers

Marble and bluestone can be carved to 5mm at a time

1. Stepper driver + stepper motor

Stepping system is the most used drive system in the market at present, the most popular is the three-phase hybrid stepping motor, which accounts for more than 90% of the market share. The reason is that the price is cheap, and the effect is good when equipped with the lassico subdivision driver. However, the defects are also obvious, such as resonance, noise, increased speed, reduced torque, easy to lose step when working for a long time, and excessive temperature rise of motor.

1. Hybrid servo driver + motor

The use of hybrid servo has not been popular in China. There are many reasons for this. There are not many foreign manufacturers of hybrid servo. Compared with AC servo, the price has no great advantage, so it can only be used in some special industries. The improvements include: improving high speed performance, reducing heating and resonance.

1. AC servo driver + AC servo motor

The use of AC servo in engraving machines is still relatively small, mainly because of the high price. In addition, the application of AC servo has certain requirements for the structure, electrical appliances, control system and transmission system of the machine tool. Just like the barrel principle, the shortest board determines the amount of water in the barrel. Therefore, the AC servo is generally applied to high-end models. AC servo has: fast response, high torque, high speed, high precision, less heating, long-time work, complete alarm system, etc. Disadvantages: different equipments need different servo parameters. High level technical engineers are required to adjust the parameters

The processing procedure of self inspection of computer gong 1. The processor must see the contents of process card before processing, know the parts, shape, drawing dimensions of the workpiece to be processed and know the processing contents of the next process. 2. Before clamping, the blank size shall be measured to meet the requirements of the drawing. When clamping, it is necessary to carefully check whether the placement of workpiece is consistent with the programming operation instruction. 3. After rough machining, self inspection shall be carried out in time to adjust the error data in time. The self inspection content is mainly the position dimension of the processing part. For example: (1) whether the workpiece is loose; (2) whether the workpiece is correctly divided; (3) whether the dimension from the processing part to the reference edge (reference point) meets the requirements of the drawing; (4) the position dimension between the processing parts. After checking the position dimension, the rough machined shape ruler shall be measured (except for circular arc). 4. After rough machining, the finishing can be carried out only after self inspection. After finishing, workers shall check the shape and dimension of the processed parts: check the basic length and width dimensions of the processing parts of the vertical plane; measure the base point dimension on the drawing for the machining parts of the inclined plane. 5. The workers can remove the workpiece and send it to the inspector for special inspection after they have completed the self inspection of the workpiece and confirmed that they are in conformity with the drawings and process requirements. High speed CNC is based on the characteristics of digital control technology. Because the effective control machine tool adopts servo motor and digital technology realizes the direct control of the working sequence and movement displacement of the parts executed by the machine tool, the transmission structure of traditional machine tool is cancelled or partially cancelled, so the mechanical structure also greatly simplifies the digital control, and requires the mechanical system to have high transmission rigidity and no transmission clearance To ensure the implementation of control instructions and the realization of control quality. At the same time, with the continuous improvement of computer level and control ability, it is possible to allow more functional parts to perform all kinds of auxiliary functions required at the same time on the same machine tool. Therefore, the mechanical cutting of CNC machine tool has higher integration function requirements than traditional machine tools. From the perspective of the requirements of manufacturing technology development, with the emergence of new materials and new processes, and the market competition for low cost requirements, metal cutting is developing towards the direction of higher cutting speed and precision, higher production efficiency and more reliable system. This requires that the CNC machine tools developed on the basis of traditional machine tools have higher precision, more driving power, better static and thermal stiffness of mechanical mechanism, more reliable work, and can achieve continuous operation and as little downtime as possible. The mechanical structure of the typical CNC milling machine is mainly composed of the basic parts, the main transmission system, the feed transmission system, the rotary table and other mechanical function accessories. The foundation of CNC milling machine is usually the structural parts of bed, column, beam, workbench and base. The size of the basic parts is large (commonly known as large piece), and the well constitutes the basic frame of the machine tool. Other components are attached to the base member, and some parts also need to move along the base member. Because the foundation plays a role of support and guidance, the requirements for the foundation are good stiffness

The importance of CNC machining spindle 1. The parameters of input starting point shall be reviewed in high-speed CNC processing. It is strictly forbidden to knock or impact the rotor end of spindle motor during operation. The operator is required to pay attention to the starting point of z-axis when aligning the tool to prevent misoperation. To avoid the impact and knife binding phenomenon in the operation process, the bearing of the spindle motor will be damaged. Once there is a phenomenon of knife binding, stop the machine immediately to prevent the bearing from causing more damage due to high-speed operation. Then, start running in from low speed, and the time is slightly longer than normal running in time, until the motor is running smoothly and normally before starting to work. 2. To ensure the motor cooling cycle system of the carving and milling machine works normally, before starting the machine. Then turn on the spindle motor, and it is strictly forbidden to use the spindle motor without cooling. The working environment temperature should not be higher than 30 ℃, when the ambient temperature is higher than 30 ℃, air conditioning shall be used, or forced cooling of the main shaft motor shall be performed by using a refrigerator. 3. The spindle motor of high speed CNC machining shall be preheated step by step according to the principle of running from low speed to high speed. When the motor reaches the required speed and the no-load operation is stable and the temperature is cooled, the machining can be carried out, so as to ensure the better machining accuracy. 4. When planning the cutter path, it is necessary to ensure the reasonable force on the spindle motor and carve according to the principle of knife provided by the technical service personnel. It is necessary to prevent vertical cutting, and it is strictly forbidden to overload the spindle motor, so as to ensure the normal service life of the spindle motor. 5. Generally, the spindle motor should be disassembled and reassembled for about one year, so as to ensure the bearing accuracy and extend the service life. In order to ensure the normal and good operation of the spindle motor, the assembly and assembly of the spindle motor must be carried out by experienced professional operators, in a clean environment and with appropriate tools. Do not knock it randomly. For the temporarily unused spindle, the residual water in the water chamber shall be blown out with compressed air, and the sleeve and shaft hole of shaft head shall be oil protected and put in a cool and dry place. 6. The high speed CNC processing water quality must be clean, and the cooling water of spindle motor uses pure water. In order to prevent the occurrence of microorganism and scale, water should be changed every seven days under normal conditions. When the surrounding environment is higher than 30 ℃ and there is no forced cooling measures, the purified water should be replaced once a day when the water temperature is the highest. In addition, operators should develop the habit of observing the water temperature during work, and change water when the water temperature exceeds 30 ℃

When engaged in precision machining, carefully do the following before work:

1. Carefully read the shift records to understand the operation and existing problems of the machine tool in the previous shift.
2. Check that the safety protection, brake (stop), limit and reversing devices are complete and in good condition.
3. Check the exposed guide rail surface, sliding surface, rotating surface and worktable of the machine tool. If there are tools, obstacles, impurities, oil stains and chips in the work center of computer gongs processing plant, they must be cleaned, wiped and oiled.
4. Check that the oil quantity of the oil storage part of the lubrication system meets the requirements and the sealing is good. The oil mark, oil window, oil cup, nozzle, oil line, felt, oil pipe and oil distributor shall be complete and in good condition and installed correctly. According to the performance requirements of lubrication diagram, carry out manual oil filling or motor-driven pump oiling, and check whether oil is coming from oil window in large gantry machining center.
5. Check whether there are new pulling, grinding and bumping on the working table, guide rail surface and main sliding surfaces of the machine tool. If any, inform the team leader or equipment personnel to check together and make records.
6. Check that the mechanical, hydraulic and pneumatic operators, such as C, valve, switch should be in the non working position.
7. Check that the electrical distribution box should be closed firmly and the electrical grounding is good.
8. If the machine tool is shut down for more than one shift, it shall run in idle for more than five minutes according to the operation procedures and requirements specified in the manual and the use of hydrostatic device.

1、 Acceptance requirements

1. Appearance inspection

(1) Check whether the finish of machined parts meets the drawing requirements.

(2) Check whether the surface of machined parts is damaged, rusted and bruised, and whether the thread shape and angle are correct.

(3) If the above problems are found, detailed records shall be made for future reference.

1. Quantity acceptance

(1) Based on the supply contract and processing voucher, check the material, specification and quantity of processed parts strictly against the drawings, and check them one by one.

(2) Make a record of quantity acceptance, indicating the place, time, participants, type, product name, quantity to be arrived and actually arrived.

1. Quality acceptance

(1) Assembly shall be carried out in strict accordance with the requirements and procedures of the general assembly drawing.

(2) Record carefully during quality acceptance. In case of quality problems of machined parts, the outsourcing processing unit shall be informed of the details in writing. Decide whether to return or replace according to the situation.

(3) In case of special requirements, the processing unit can be consulted for joint acceptance and assembly, and the acceptance documents can be signed after the installation is qualified.

2、 Acceptance procedure

1. After the processing parts of large mechanical parts are received, the full-time acceptance personnel shall be sent to check and accept the material, specification, model and quantity of the processed parts according to the requirements of the contract drawings.
2. The acceptance period is generally 1-2 days. The special situation depends on the effect of use. In case of quality problems, we can return the products to the processing unit, claim for compensation, and bear the economic losses of the processing unit.
3. Generally, the processing contract signed by the non production department will be directly accepted by the user department, and the acceptance report will be filled in.
4. If the unqualified parts are accepted by experience, the acceptance personnel must handle the maintenance and return procedures within the specified acceptance period.
5. For the acceptance of special precision machining parts, the full-time acceptance personnel shall organize relevant personnel for joint acceptance, and fill in the acceptance report in detail. For the unqualified parts, fill in the inspection form in detail. CNC machining is the condition to improve the machining accuracy and determine the selection direction of the parts outsourcing manufacturer in the future.

The main reason for the failure of plastic mold is due to improper heat treatment process, such as heating temperature, holding time, cooling speed and so on. Plastic mold in the process of processing, cracks or deformation, surface oxidation and decarburization phenomenon, is mainly because the mold failure.

First of all, on the impact of oxidation and decarburization, mainly because the mold quenching is stopped at high temperature, but can not be strictly controlled. In addition, after decarburization on the surface of the die, quenching cracks are caused due to the difference of microstructure between the inner and outer layers and the larger structure stress during cooling.

The second is about the rate of heating. Because the die steel contains more carbon and alloy elements and poor thermal conductivity, the heating speed should not be too fast and should be stopped slowly to avoid deformation and cracking of the die. In order to avoid oxidation and decarburization during heating and quenching in air furnace, the heating speed should not be too fast and the diathermy should be slow.

The above will not produce large thermal stress, relatively safe. If the heating speed of the mold is fast and the diathermy is fast, the thermal stress inside and outside the mold will be very large. If the control is not good, such as deformation or crack, it is very easy to occur, in the prevention, it is necessary to use preheating or slow down the heating rate.

Due to the large size of the worktable and die, it must be able to meet the requirements of large-scale worktable and die, In addition, small diameter end mills with large elongation are often used to process the mold cavity, so chatter is easy to occur in the processing process.

In order to ensure the machining accuracy and surface quality of parts, the high-speed universal milling machine manufactured by mould must have high dynamic and static stiffness to improve the positioning accuracy, tracking accuracy and anti vibration ability of the machine tool.

High speed and high-power high-speed machining is the development direction, high-speed milling has shown great advantages in mold processing. In order to adapt to the processing of the mold cavity surface, the radius of the tool should be less than the minimum radius of the cavity surface, so as to avoid “interference” between the tool and the workpiece. Because of the small diameter of the tool, the spindle speed is required to be very high. The main shaft speed of foreign high-speed machine tools has reached 40000-100000 R / min, and the rapid feed speed can reach 30000-60000 min. The rough and finish machining of the cavity and other parts of the mold parts is often completed in one-time clamping of the workpiece, so the spindle power should be high. The spindle power of the medium-sized mold milling machine and machining center is usually 10-40kw, some even higher.

The die cavity is composed of complex six curved surfaces and grooves, and many dies have deep cavity. In order to achieve high precision, high speed and high stability machining of 3D surface, the machine tool needs multi axis linkage, and has good comprehensive cutting ability of deep hole cavity. Five axis linkage machining center can be used, in addition to the linear motion of three coordinates, there are also two rotation coordinates of feed motion. The milling head or worktable can realize continuous rotary feed by multi axis linkage, so it is suitable for machining mold parts with complex cavity surface. It can be said that compound machining is one of the development directions of mold processing.

Processing center is written language, English Name: CNC machining center; computer gong is a common saying, more in Hong Kong, Taiwan and Guangdong. In this area, milling machines are called gongs when they are in the machining center, so milling machines are also called gongs, and computer gongs are also derived from this. Computer gongs, as the name implies, are gongs controlled by computers, so they are also called CNC milling machines. In fact, they are upgraded from CNC milling machines. The original principle is the same. The difference is that the machining centers use good materials with high precision, high speed and load The traditional CNC milling machine is half cover type, and most of the machining center has been changed to full cover type, which is more safe for processing and can effectively prevent the overflow of iron chips and the splashing of chips. Computer gong is an automatic machine tool equipped with program control system. The control system can process and decode the program with control code or other symbol instructions logically, so that the machine tool can move and process parts. Also known as CNC machining mold or CNC machine tools.

The computer gong can be divided into two parts, the body part and the system part.

Fuselage part:

1) Casting, which is the most important part of computer gongs, directly affects the accuracy, stability, wear resistance and the life of machine tools. After the casting is finished, it is not immediately used in production. A good casting is that it is subjected to wind and rain, sunlight exposure, natural weathering, and some of them are soaked in sea water. After the casting does not change, the machine tool is not easy to change and can maintain the stability and accuracy of the machine tool for a long time.

2) Spindle, the spindle is used to directly face the workpiece. It is driven by the motor to rotate at a high speed. If the tool holder is installed on the spindle, the workpiece can be cut to meet various production needs. The quality of the spindle will also directly affect the machining accuracy. If the internal bearing is worn, it will easily cause the spindle to swing, and the accuracy of the processed things will naturally have a deviation of several wires 。 At present, the speed of the spindle is generally around 8000 rpm, and the high-speed machine can achieve more than 20000 revolutions. Each machine has only one spindle.

3) Screw rod is also a machine

The fuel consumption of Wheeled Construction machinery is one of the major construction costs. Therefore, the fuel oil with freezing point 3-5 ℃ lower than the minimum temperature should be selected according to the temperature of the construction area. The fuel saving measures for construction transport vehicles and engines are as follows:

(1) Try to reduce the weight of the vehicle. Increasing vehicle weight will increase fuel consumption correspondingly. Therefore, unnecessary additional equipment should be removed from the vehicle during construction without affecting the project quality

(2) The resistance to acceleration and fuel consumption should be reduced as much as possible.

In construction, if the speed is below 400km / h, the air resistance can be ignored. It should be noted that the rolling resistance. When the vehicle is driving on an uneven road surface, the deformation of suspension device and tire increases due to its frequent jumping, resulting in a large increase in rolling resistance. Compared with the situation of driving on good road surface, the fuel consumption increases by 30% – 50%. Therefore, it is necessary to repair and maintain the construction access road. At the same time, the tire pressure has a great influence on the rolling resistance. If the tire pressure is reduced on the hard road surface, the tire deformation will be large and the rolling resistance will be increased; if the tire pressure is reduced on the soft road surface, the contact area between the tire and the ground will increase, and the pressure per unit area will decrease, which will reduce the rolling resistance. Therefore, it is necessary to pay attention to the changes of road conditions in construction and select appropriate tire pressure to reduce fuel consumption.

The transmission ratio of each gear of vehicle transmission has a great influence on fuel consumption. The high-speed gear with small transmission ratio should be selected as far as possible in construction, so as to save fuel.

(3) Increase the engine compression ratio to the standard value. The compression ratio of diesel engine is generally between 16 and 22. With the increase of compression ratio, the temperature and pressure at the end of compression are increased, which is beneficial to the combustion and expansion of the mixture, the thermal efficiency of the engine is improved, the effective power is increased and the fuel consumption is reduced. The specific measures are as follows:

Reduce the resistance of the intake system. The filter should be cleaned and maintained in time to ensure that there is enough air to enter the cylinder in time.

Keep the vehicle in good condition. For the engine cylinder pressure, the general diesel engine should not be less than 20% of the original engine standard pressure, gasoline engine is not less than 30%. For the pressure difference between each cylinder, the diesel engine is generally required to be no more than 8%, and the gasoline engine is not more than 10%. If the cylinder pressure does not reach the specified standard, grind the valve and replace the piston ring as required. It should also be noted that the carbon deposit in the combustion chamber will make the compression ratio increase automatically. If the compression ratio is too high and the carbon deposit is too high, it is easy to cause the cylinder deflagration and increase the fuel consumption. Therefore, it is very necessary to remove the carbon deposit. In addition, the clearance between the inlet and exhaust valves must be adjusted to the specified value, because the fuel consumption will be increased if the clearance is too large or too small.

(4) Good engine fuel supply angle in advance. If the fuel supply advance angle is too large or too small, the fuel consumption of the engine will increase. Therefore, in order to make the engine have good performance, the fuel supply advance angle must be calibrated.

(5) Reduce fuel consumption per unit load. If the vehicle condition permits, the productivity can be increased and the fuel consumption per unit weight can be significantly reduced by increasing the vehicle load to the rated load.

(6) Master the economic speed. In construction, the roads are generally informal roads, that is, access roads. In this case, the correct relationship between safety, fuel consumption and vehicle speed should be grasped. Taking the half load of Tatra T815 as an example, the relationship between fuel consumption and vehicle speed is: when the vehicle speed is 25-30km / h, the fuel consumption is the least, that is, in the construction, this speed can not only ensure the production efficiency, but also be economical and reasonable.

(7) Choose lubricating oil correctly. The selection of lubricating oil is the key factor to reduce power consumption and fuel consumption. Different specifications and brands of lubricating oil should be selected in winter and summer.

First of all, strictly abide by the tire inflation standards, check whether the ministries and commissions have air leakage after inflation, and regularly check the tire pressure to ensure compliance with the standards. Develop the habit of using a barometer to measure air pressure. Do not judge with naked eyes. Ensure that the tire has a certain elasticity, when bearing the specified load, make its deformation not exceed the specified range, and ensure the vehicle has good stability and comfort in driving. The pressure of the spare tire should be higher to avoid running away for a long time.

Secondly, it is necessary to select and install the tire correctly, and use the corresponding inner tube according to the tire specification. Tires assembled on the same machine shall be of the same brand, structure and performance. If this is not possible, tyres of the same brand, specification, pattern and type should be assembled on the same axle; when replacing new tires, the whole vehicle or coaxial should be changed at the same time; tires with directional patterns should be installed in accordance with the specified rolling direction; when replacing new tires, the new tires should be installed on the front wheels, and the repaired tires should be installed on the rear wheels. In order to ensure driving safety, the retreaded tires are not allowed to be used as steering wheels (front wheels).

Third, regular tire rotation. After the vehicle has been running for a period of time, the front and rear tires are different in terms of fatigue and wear. Therefore, it is necessary to change the position in time according to the regulations. There are two ways to change tires: cross method and cycle method. The cross transposition method is suitable for the vehicles which often drive on the road with greater camber, while the cyclic transposition method is suitable for the vehicles that often drive on the flat road.

Fourth, it is also necessary to control the temperature of the tire. In the process of driving, the tire will generate heat due to friction and deformation, which will increase the temperature and pressure inside the tire. When the temperature of the tire is very high, we can’t use the method of deflating and depressurizing, and we can’t pour water on the tire to reduce the temperature, so as to avoid accelerating the damage of the tire. Should be in

Turning is to change the shape and size of the blank by using the rotary motion of the workpiece and the linear or curvilinear motion of the cutter on the lathe, so as to meet the requirements of the drawing.

Turning is a method of cutting workpiece on a lathe by rotating the workpiece relative to the cutter. The cutting energy of turning is mainly provided by the workpiece rather than the cutter. Turning is the most basic and common cutting method, which plays an important role in production. Turning is suitable for machining rotary surface. Most of the workpieces with rotary surface can be machined by turning method, such as inner and outer cylindrical surface, inner and outer cone surface, end face, groove, thread and rotary forming surface, etc. the tool used is mainly turning tool.

In all kinds of metal cutting machine tools, lathe is the most widely used one, accounting for about 50% of the total number of machine tools. The lathe can be used not only for turning the workpiece, but also for drilling, reaming, tapping and knurling with drills, reamers, taps and knurling cutters. According to the different process characteristics, layout forms and structural characteristics, lathes can be divided into horizontal lathe, floor lathe, vertical lathe, turret lathe and profiling lathe, and most of them are horizontal lathes.

The ideal processing program should not only ensure the qualified workpiece in accordance with the drawing, but also make the function of CNC machine tool be reasonably applied and fully developed. CNC machine tool is a kind of high efficiency automation equipment, its efficiency is 2 ~ 3 times higher than ordinary machine tool. In order to give full play to this characteristic of CNC machine tool, we must analyze the process of workpiece before programming, and select economic and reasonable process scheme according to specific conditions. The improper consideration of turning process is an important factor affecting the machining quality, production efficiency and processing cost of CNC machine tools. It is a process of changing the overall dimension or performance of workpieces with processing machinery. According to the temperature state of the workpiece to be processed, it can be divided into cold working and hot working. Generally, it is processed at normal temperature and does not cause chemical or physical changes of the workpiece, which is called cold working. Generally, the processing above or below the normal temperature will cause the chemical or physical phase changes of the workpiece, which is called thermal processing. Cold working can be divided into cutting and pressure machining according to the difference of processing methods. Heat treatment, forging, casting and welding are common in hot working. There are two steps in the formulation of machining process specification. First of all, it is to draw up the process route of parts processing, and then determine the process size of each process, the equipment and process equipment used, as well as the cutting specifications, man hour quota, etc. These two steps are interrelated and should be analyzed comprehensively.

The main task is to select the processing method of each surface, determine the processing sequence of each surface, and the number of processes in the whole process.

General principles for drawing up process routes

1. Machining datum plane first

In the process of machining parts, the surface as positioning reference should be machined first, so as to provide precise reference for subsequent processing as soon as possible. It is called “benchmark first”.

1. Dividing processing stages

The surface with high machining quality is divided into three stages: rough machining, semi finishing and finishing. It is mainly to ensure the processing quality, to use the equipment reasonably, to arrange the heat treatment process, and to find the blank defects easily.

1. Face before hole

For parts such as box, bracket and connecting rod, the plane should be machined first and then the hole should be processed. In this way, the hole can be processed by plane positioning, which can ensure the position accuracy of plane and hole, and the machining of hole on the plane is convenient.

1. Finishing

The finishing of the main surface (such as grinding, honing, finishing grinding / rolling, etc.) shall be carried out at the last stage of the process route. The surface finish after processing shall be ra0.8um. Slight collision will damage the surface. In Japan, Germany and other countries, after finishing, flannel shall be used for protection. It is absolutely forbidden to directly contact the workpiece with hands or other objects to avoid polishing The finished surface is damaged due to transportation and installation between processes.

Machining surface quality refers to the micro unevenness of the machined surface of parts after machining, also known as roughness. It is indicated by three codes of RA / RZ / ry and numbers. There will be corresponding surface quality requirements in mechanical drawings. Generally, the surface with surface roughness Ra < 0.8um is called mirror surface. The surface quality after machining directly affects the physical, chemical and mechanical properties of the workpiece. The working performance, reliability and service life of products depend on the surface quality of main parts to a great extent. Generally speaking, the surface quality requirements of important or key parts are higher than that of ordinary parts. Machining this is because the table and good quality parts will greatly improve its wear resistance, corrosion resistance and fatigue damage resistance

This is to use electrical and chemical energy to dissolve anode and remove burr. The anode is on the side of the positive pole of the part and the DC power supply. The cathode is connected with the forming tool and the negative pole of the DC power supply. There is a certain gap between the two poles to make the electrolyte circulate. When the anode and cathode are immersed in the solution and connected with direct current, electrochemical reaction occurs on the anode surface. The dissolved metal on the surface of the part forms viscous liquid with high resistance and small corrosion. The burr protrudes from the surface of the part, and the liquid film is difficult to form under the influence of temperature difference. After power on, the power line is highly concentrated on the burr The burr nearest to the cathode will be dissolved at the fastest speed until the burr is completely dissolved and the edge gradually forms a fillet, that is to say, the purpose of deburring is achieved.

Electrolytic deburring machine can be used. When the production volume is not large, a simple equipment can be made by converting the alternating current of rectifier into direct current. According to the structure of the parts, the special fixture (tool cathode) similar to the part shape is made of brass or red copper and other conductive materials. The unprocessed parts are coated with epoxy resin for isolation protection. The commonly used electrolytes are NaCl, NaNO2 > and nano > 3.

This method is suitable for nonferrous and ferrous metal parts, especially for parts with complex shape and burr on inner hole, cross hole and inner surface which are difficult to remove by mechanical and manual methods. It can remove the burr of extra hard parts such as molybdenum, nickel, titanium and quenched parts. Put the cleaned metal parts into the chemical solution (50 ℃), and the metal on the surface of the parts will be transferred to the solution in the form of ions. These ions gather on the surface of the workpiece and form a layer of sticky film with high resistance and low conductivity through chemical reaction to protect the workpiece surface from corrosion. The burr protrudes from the surface, and the chemical action will remove the burr. When processing, only one slot can be used. According to the different materials of deburring workpiece, different chemical solutions are used. The main components of the base can be hydrochloric acid, phosphoric acid, sulfuric acid, diphenylaniline hydrochloride and water. Chemical deburring is suitable for small metal parts, and can remove fine burr with thickness less than 0.07 mm.

Milling: refers to the use of rotating multi edge cutting tools to cut workpiece, is a high efficiency processing method. When working, the tool rotates (as the main motion), and the workpiece moves (as the feed motion), and the workpiece can also be fixed, but at this time, the rotating tool must also move (complete the main motion and feed motion at the same time). There are horizontal milling machine or vertical milling machine and large gantry milling machine. These machine tools can be ordinary machine tools or CNC machine tools.

1) Plane parts

The characteristics of plane parts are shown in that the machining surface can be parallel to or perpendicular to the horizontal plane, and can also form a fixed angle with the horizontal plane. At present, most of the parts processed on the CNC milling machine belong to the plane type parts, and the plane parts are the simplest type of parts in the NC milling process. Generally, only the two axis linkage or three axis of the three-dimensional CNC milling machine is needed Linkage can be processed. In the process of machining, the machining surface is in contact with the cutter, and the end mill or nose cutter can be used for rough and finish machining.

(2) Curved surface parts

The feature of curved surface parts is that the machining surface is a spatial surface, and the machining surface and milling cutter are always in point contact in the process of machining. Ball end milling cutter is often used for surface finishing.

China’s mold industry has experienced rapid development in recent years, and the achievements have been considerable, especially since the beginning of the year, under the guidance of the national twelfth five year plan, the industry vigorously develops high-end precision equipment, and constantly promotes the steady progress of China’s mold industry.

According to experts, due to the development of die and mold industry in recent years to a larger, more precise, more complex and more economic and rapid direction, so the requirements for the miniaturization and precision of its products are higher, which urges China’s mold industry to constantly improve and upgrade technology to adapt to the changing market environment. According to relevant data, in terms of precision plastic mold, China has been able to produce plastic parts mold for camera and mobile phone, multi cavity small module gear mold and 7800 cavity plastic sealing mold with accuracy of 5 μ M.

In recent years, domestic die steel production has made great progress. At present, many domestic steel mills are mass producing some steel grades with strong universality or excellent performance internationally, such as 4Cr5MoSiV1 (equivalent to aisih13), 3Cr2Mo (equivalent to aisip20), 10ni3mncaal, Cr12MolV1 (equivalent to aisid2), etc. Among them, 4Cr5MoSiV1 and 3Cr2Mo are relatively large in production and use, and their research and improvement are also in-depth.

Reducing material cost and improving performance price ratio have become the focus of new die steel development in advanced die steel production enterprises. For example, when Hitachi Metal Co., Ltd. and Datong Special Steel Co., Ltd. introduced their products at the technical exchange meeting during the exhibition, they all agreed to develop dac-magic hot working die steel, hpm-magic and cena1 plastic mold steel and dha-world die-casting die steel to cope with the financial crisis and more fierce market competition.

Generally speaking, some well-known die steel manufacturers abroad still have obvious advantages in the production means, variety specifications, serialization degree, after-sales service and awareness and effect of developing new steel grades. CNC machine tool processing of domestic die steel serialization degree and quality stability is still to be improved; the proportion of production and application of some good performance die steel is still low, the application of most new steel is still small, at the same time, there is a lack of effective means of promotion and sales, post-sale service needs to be improved; in addition, some new steel grades with special performance need to be developed. Improving and perfecting the above shortcomings will still be the main task of die steel development in China in the future.

报错 笔记

The application of large-scale iron plate processing stainless steel shows that the mold working in the chemical corrosive environment must have corrosion resistance, and also requires certain hardness, strength and wear resistance. The common martensitic stainless steels are 2Cr13, 3Cr13, 4Cr13, 3cr17mo, 9Cr18, 9Cr18Mo, cr14mo4v, 1Cr17Ni2, etc. According to the requirements of hardness, several kinds of stainless steels are introduced as follows: 1. The application of medium carbon high chromium corrosion-resistant martensitic stainless steel requires a hardness of about 50-55hrc. The typical stainless steel is 4Cr13, which is medium carbon martensitic stainless steel. After heat treatment, it has high hardness and wear resistance, and is resistant to atmospheric and steam corrosion. It can be used to manufacture plastic mold with certain corrosion resistance. The quenching temperature of the steel is generally 1050 ℃, and the steel has good hardenability. For small plastic molds, air cooling can be used to reduce the heat treatment deformation of the mold; while oil quenching can be used for the large-size mold. The quenched mold is generally tempered at 200-300 ℃, and the hardness after tempering is 50-53hrc. Suitable for manufacturing moulds of plastic products under contractor’s load, high wear resistance and corrosive medium. 2. In the application of high carbon and high chromium stainless steel, high carbon and high chromium stainless steel, such as 9Cr18, cr18mov, cr14mo, cr14mov, can be selected for the corrosion-resistant plastic mold with high hardness and high wear resistance. Taking cr14mov as an example, the carbon content of cr14mov is 1.0% – 1.15%. The steel has good hardenability. The quenching temperature is 1100-1120 ℃, the hardness is more than or equal to 58 HRC, the tempering temperature is 500 ℃, the holding time is 2 h, and the tempering time is 4 times. The hardness of cr14mov steel is greater than or equal to 60 HRC. The steel has high hardness, high wear resistance, good corrosion resistance, and high temperature hardness. It is suitable for manufacturing plastic mold with high load and high wear resistance under the action of corrosive medium. 3. Application of low carbon Cr Ni corrosion resistant stainless steel 1Cr17Ni2 steel belongs to martensitic stainless steel, which has good corrosion resistance to oxygen acids (nitric acid at a certain temperature and concentration, most of organic acids) and salt aqueous solutions; the steel has higher strength and appropriate hardness, but its performance is better than 4Cr13 steel. Therefore, some plastic molds with high corrosion resistance are still made of this type of stainless steel. The quenching temperature range of 1Cr17Ni2 steel is 950-1050 ℃. After quenching, the hardness of steel is 38-40hrc after tempering at 200-300 ℃. If the austenite is transformed into martensite, the hardness can be increased to 42-48hrc. The strength, hardness, wear resistance and corrosion resistance of the steel are higher. The tempering temperature is 600-700 ℃, and the basic structure of the steel is tempered sorbite, which has good combination of strength and toughness and high corrosion resistance. This kind of steel can also be nitrided to improve the wear resistance, anti bite ability and the service life of the die.

According to the parts, quantity and accuracy requirements, the charging method is as follows: 1. General materials for drilling and processing; 2.5 times of the diameter; 2.5 times of the diameter; 0.05; 0.12; 0.12; 0.12 For small holes not less than 0.5 yuan), the basic price * depth diameter ratio * 0.4 shall be charged for general materials with the depth diameter ratio greater than 2.5, the base price * 5 shall be charged for the hole diameter accuracy requirement less than 0.1 mm or the center distance requirement less than 0.1 mm; the tapping charge standard shall be charged according to the tap diameter * 0.2 (with cast iron as the standard, and steel parts with an additional * 1.2) shall be charged at the standard base price * 0.2-0.8 during batch processing (according to the batch size and addition) Ease of work) Computer gong processing, mechanical parts processing, CNC machine tool processing, Dongguan high speed computer gong processing lathe, general precision optical axis machining, for small length diameter ratio and 10, it is charged according to the blank size * 0.2 (the minimum is 5 yuan) ﹥ if the length diameter ratio is greater than 10, it will be charged according to the general optical axis base price * length diameter ratio * 0.15, or the precision requirement is within 0.05mm or the taper is required to be charged by the general optical axis base price * 2 The general step shaft (fan shaft, pump shaft, reducer shaft, grinding wheel shaft, motor shaft, spindle, etc.) is charged at the basic price * 2 for general precision smooth shaft processing, or * 3 for the step shaft with taper, inner and outer rib, or for general-purpose screw, it is processed according to the general precision optical axis Base price * 4 charge the general flange parts according to the material diameter * 0.07, and the diameter greater than 430mm is charged according to the material diameter * 0.12. \General round nut parts are charged according to diameter * 0.25 (including materials) generally trapezoidal, triangle nut parts are charged by diameter * 0.3 (excluding materials); (general shaft sleeve parts (diameter less than 100, diameter length ratio less than 2) are charged by material outer diameter * 0.2, and those with diameter length ratio more than 2 are charged according to diameter length ratio * base price * 0.6. Generally repair bearing platform parts with wear loss less than 2mm, diameter less than 40mm and width less than 25m M each 5 yuan, need to be on the central shelf, or the length of more than 1.7 meters of the base price * 2 charge. If the diameter is greater than 40mm, it shall be charged according to the diameter * 0.2. \For milling machine processing, general keyway processing (length width ratio less than 10) keyway width * 0.5 (minimum 5 yuan). If the aspect ratio exceeds 10, it shall be charged according to the aspect ratio * base price * 0.1. If there is strict position requirement, it will be charged according to the base price * 2. Processing of materials with hardness greater than hrc40

1. The machine bed forward and backward, beam up and down, vertical milling head up and down are equipped with Taiwan ball screw, driven by servo motor.
2. Unique cross beam lifting safety interlock device, grinder processing to ensure the repeated positioning accuracy of the machine tool.
3. The side milling head is equipped with V5 type gantry milling head. The computer gong processing is equipped with independent lubrication device. The lifting is driven by ordinary reducer and frequency conversion speed regulation.
4. The vertical milling head of gantry precision grinder is equipped with tx400 heavy gantry milling head, double rectangular guide rail, strong rigidity; the milling head is equipped with ball screw, pneumatic broach device, driven by servo motor.
5. The three-axis CNC system of general milling / CNC milling with one key conversion for gantry precision grinder is not only programmable, but also can be operated manually by using the extended panel. It is very practical in the actual machining process.

Do not cut off the connection of protective devices when repairing the electrical equipment of large water mill.

Electrical maintenance personnel shall wear insulating gloves and rubber shoes during maintenance to avoid electric accidents. And do not wear metal jewelry and other conductive articles that may cause electric shock.

Before overhauling electrical equipment, it is necessary to follow the instructions of relevant warning nameplates and use appropriate three-way ammeter to determine that the circuit is in open circuit state.

The main power switch should be cut off and warning signs should be set up to avoid accidental injury caused by reactivating the large water mill without knowing it.

When the motor is activated, sparks may be generated at the contact point of the electrical box. Therefore, the machine can not be used in dust, gas explosion and flammable places.

The electric box of large water mill is designed to provide safe operation of the machine. No one is allowed to modify the structure and circuit design of this electrical box without the authorization of our company.

The operator must be familiar with the position of emergency stop switch and main power activation switch of large water mill. In case of emergency, the machine can be stopped and the power supply can be cut off as soon as possible. Process specification is one of the process documents that stipulate the machining process and operation method of parts. Under specific production conditions, the more reasonable technological process and operation method are written into the process in accordance with the prescribed form; the large-scale CNC machining center for gongs processing is a kind of tool library with automatic tool change, and the workpiece can be in a certain degree CNC machine tools for various processing operations within the scope.

Because the machining center can finish many kinds of working procedures in a centralized and automatic way, it can avoid the artificial operation error, reduce the time of workpiece clamping, measuring and machine tool adjustment, as well as the time of workpiece turnover, handling and storage, and greatly improve the processing efficiency and accuracy, so it has good economic benefits. Machining center can be divided into vertical machining center and horizontal machining center according to the position of spindle in space.

Large computer gong machining centers are usually classified into horizontal, vertical and multi axis linkage machining centers according to the relative position of the spindle and the worktable.

A horizontal machining center: it refers to the machining center with the spindle axis parallel to the worktable, which is mainly suitable for processing box type parts.

B vertical machining center: it refers to the machining center with the spindle axis perpendicular to the worktable. It is mainly used for processing complex parts such as plates, plates, molds and small shells. C multi axis linkage machining center, also known as universal machining center, refers to the machining center which can control the linkage change through the angle between the spindle axis and the rotary axis of the worktable to complete the machining of complex spatial curved surface. It is suitable for machining impeller rotor, mould, cutting tool and other workpieces with complex space curved surface.

After the workpiece is clamped once, the CNC system can control the machine tool to automatically select and change the tool according to different working procedures; it can automatically change the spindle speed, feed rate of Dongguan CNC machining center, the motion path of the cutter relative to the workpiece and other auxiliary functions, and automatically carry out multiple processes such as drilling, countersinking, reaming, boring, tapping, milling and so on Processing.

Because the early milling machine numerical control system does not have the function operation function, the processing program of function equation curve cannot be compiled directly by G code, (the lower version) CAD / CAM software usually does not have the function of directly inputting graph from equation, so it is very difficult to process function equation curve contour.

The programming method of machining center: the contour composed of simple contour line and arc is directly programmed with G code of NC system. The complex profile of 3D surface is drawn by CAD / CAM in the computer, and the corresponding parameters are set according to the surface type, and the NC machining program is generated automatically. The above two programming methods can basically meet the requirements of NC machining.

The process of large-scale mechanical parts processing plant is to change the shape, size, relative position and nature of the production object to make it into finished or semi-finished products on the basis of the process. It is the detailed description of each step and process. For example, as mentioned above, rough machining may include blank manufacturing, grinding, etc. mechanical precision parts processing may be divided into turning, fitter, milling machine, And so on, as much as the tolerance of each step has to be achieved.

What are the technical requirements for large-scale machining?

Only by complying with these technical requirements can the finished products of large-scale machining be more standardized and reasonable. In large-scale machining, what are the technical requirements to be observed?

The specific technical requirements are as follows:

(1) Remove oxide scale from parts.

(2) Undeclared shape tolerance shall conform to GB118

报错 笔记双语对照
排序
重点词汇
重点词汇
伺服电机 【计】servo motor
连锁装置 interlock ; interlocking device
润滑装置 lubricating arrangement