NC machine tool programming technology is not a very short period of time to learn, need to learn step by step, and slowly accumulate experience. Mastering this technology is not only the theoretical level of engineers, but also the practical experience and practical ability of senior technicians.
3, skilled CNC machine tools. It takes 2-3 years to study. In this process, we need to learn how to operate the system, fixture installation, part benchmark alignment, tool presetting, set zero offset, set tool length compensation, radius compensation, tool and handling handle, cutting tool grinding, part measurement (skilled use of vernier caliper, micrometer card, micrometer, micrometer, diameter bar meter), etc.
4, must have good fixture foundation and measurement technology.
A set of products usually have several or more than ten parts. The main matching dimensions of these parts are guaranteed by computer gong processing. It is very important to choose a reasonable tolerance, especially some product design drawings do not consider the matching problem. Bottom, surface, shell fit, shape is no doubt 0 to 0 fit, positioning is guaranteed by the mouth, concave mouth and convex mouth tolerance is generally 0.1 mm, unilateral. The fit on the big body is like a transparent mirror. The shape of the general accessories is 0.1 ~ 0.2 smaller than the size on the big body. The shape of the movable accessories on the big body, such as buttons, is 0.1 ~ 0.5 smaller than the shape on the big body. The surface shape of the accessories on the big body is generally consistent with the surface shape on the big body, which can be removed from the big body.
1、 Exit angle (draft angle)
All plastic molds should have a mold angle, otherwise they will be scratched. If it is not indicated in the drawing, you can discuss with the mold maker. The mold angle is generally 0.5 ~ 3 degrees. If the mold is etched, the mold angle should be larger, 2 ~ 5 degrees, depending on the thickness of the etched pattern.
2、 Cutting problem
Most of the time, when the cutter is just milled, the amount of cutting is relatively large, which is easy to cause the cutter to break and bounce. At this time, you can first roughen the lower cutter position, or lift the cutter away, or lower the cutter outside the material in the daytime. In a word, this problem should be fully considered. Grab the knife, spring the knife, drop the knife, when the processing capacity is relatively large, the knife clip is too long, the knife is too small, this often happens. When the processing capacity is relatively large, especially when the concentration feed is large, it is easy to occur. For example, when the depth of the smooth side is 50 mm and the diameter is 3 / 4, we can process it in 25 mm twice, so it is not easy to occur. Tool clamping is too long, the length of the tool is very important for processing, should try to clamp short, beginners are easy to ignore this problem, the program paper must indicate the length of the tool clamping. It’s easy to grab the knife when turning the corner. The solution is to use a smaller knife to clear the corner layer by layer, and then change the larger knife to smooth the side.
3、 Sharpen a knife
The shapes of computer gongs are different, so we often need to grind all kinds of knives. When all kinds of molding knives are worn out, we also need to grind them. Only when we reach the following points can we grind a usable knife.
4、 Milling direction
The reason is that the rigidity of the computer gong is relatively good, it is not easy to let the cutter, the back clearance is small, and the milling shape or inner groove is left compensation. When machining left and right symmetrical shapes, the profile tool path cannot be mirrored, otherwise the processing effect of the mirrored side is not good. In order to communicate with the operator of the machine tool, the program paper should include:
High speed CNC machining can change the shape and size of products, which plays a very important role.
The broad meaning of benchmark is “basis”. The datum in mechanical manufacturing refers to the points, lines and surfaces used to determine the geometric relationship between the geometric elements on the production object. According to different functions and applications, datum can be divided into design datum and process datum, and process datum can be divided into process datum, positioning datum, measurement datum and assembly datum.
The technology of high-speed CNC machining is the premise to ensure the production of high-quality parts.
On lathe, the shape and size of the blank can be changed by the rotary motion of the workpiece and the linear or curvilinear motion of the cutter, and it can be processed to meet the requirements of the drawing. Ordinary machine tools are more and more difficult to meet the needs of processing precision parts, at the same time, due to the improvement of production level.
The price of CNC machine tools is falling from time to time. CNC precision parts processing mainly includes ultra precision turning, mirror grinding and grinding.
The primary premise of CNC precision parts processing is the accuracy of process datum. Datum on mechanical drawings are represented by capital letters a, B, C, D, etc. with a specific reference symbol with circle. When the reference symbol is aligned with the surface and its extension line or the dimension limit of the surface, the surface is taken as the datum. When the datum mark is aligned with the dimension line, it means that the solid center line of the dimension is taken as the datum. It is a more general statement that the process is accurate.
Assembly benchmark refers to the precision used to determine the position of parts in components or products during assembly.
Measurement datum refers to the specification for the size and position of the machined surface to be measured during the inspection of parts. Positioning datum refers to the datum used for positioning the workpiece in the machine tool or fixture during machining.
The lubrication function of metal cutting fluid in the cutting process can reduce the friction between the rake face and the chip, and between the flank and the machined surface, forming a part of lubricating film, thus reducing the cutting force, friction and power consumption, reducing the surface temperature and tool wear of the friction part between the tool and the workpiece blank, and improving the cutting performance of deep hole machining workpiece materials . In the grinding process, after adding grinding fluid, the grinding fluid seeps into the grinding wheel grain workpiece and grain debris to form a lubricating film, which reduces the friction between the interfaces, prevents the abrasive cutting edge from wearing and adhering to the chips, thus reducing the grinding force and friction heat, and improving the durability of the grinding wheel and the surface quality of the workpiece.
The cooling effect of cutting fluid is to take the cutting heat away from the cutting tool and workpiece through the convection and vaporization between the cutting fluid and the heated cutting tool (or grinding wheel), chip and workpiece, so as to effectively reduce the cutting temperature, reduce the thermal deformation of the workpiece and cutter, maintain the hardness of the cutter, and improve the machining accuracy and the durability of the cutter. The cooling performance of cutting fluid is related to its thermal conductivity, specific heat, heat of vaporization and viscosity (or fluidity). The thermal conductivity and specific heat of water are higher than that of oil, so the cooling performance of water is better than that of oil.
Deep hole machining in the process of metal cutting, cutting fluid is required to have a good cleaning effect. Remove the generated chips, grinding chips, iron powder, oil and sand particles, prevent the contamination of machine tool, workpiece and cutter, keep the cutting edge of cutter or grinding wheel sharp, and do not affect the cutting effect. For oil-based cutting oil, the lower the viscosity, the stronger the cleaning ability. Especially for cutting oil containing kerosene, diesel and other light components, the better the permeability and cleaning performance. The water-based cutting fluid containing surfactant has better cleaning effect, because it can form an adsorption film on the surface, prevent particles and oil sludge from adhering to the workpiece, cutter and grinding wheel. At the same time, it can penetrate into the interface where particles and oil sludge adhere, separate it from the interface, take it away with the cutting fluid, and keep the cutting fluid clean.
In the process of metal cutting, the workpiece will be corroded by contacting with corrosive media such as environment media and oil sludge produced by decomposition or oxidation of cutting fluid components, and the surface of machine tool parts in contact with cutting fluid will also be corroded. In addition, when the workpiece is temporarily stored after processing or in the process of circulation between processes, the cutting fluid is also required to have a certain anti rust ability, so as to prevent corrosive substances such as environmental media and oil sludge in the residual cutting fluid from eroding the metal.
CNC machining skills: CNC machine tool installation and debugging of the work first depends on the new CNC machine tool is a small machine tool or a large machine tool. Generally, the installation of small CNC machine tools is relatively simple, while the transportation and packaging of large CNC machine tools must be considered. Therefore, the whole machine tool has to be divided into several parts. After arriving at the work site, it must be reassembled and carefully adjusted. The workload is large and complex. Comparatively speaking, small CNC machine tools can avoid the workload of reorganization after decomposition. However, the open box acceptance and start-up debugging of small CNC machine tools must also be treated seriously and carefully to avoid mistakes and losses. Usually, the debugging of CNC machine tools must go through the following steps.
(1) At the beginning, we did it on the spot. Before the arrival of the machine tool, the installation foundation of the machine tool shall be laid according to the foundation drawing provided by the machine tool factory, and the preset holes of the anchor bolts shall be reserved; the spare parts, accessories, data and accessories shall be counted according to the packing list; the attached documents shall be kept by a special person (especially the detailed list of the parameter setting of the numerical control machine tool, etc.); According to the instructions, all parts of the machine tool must be in place on the site, and all fasteners must be in place according to the number.
(2) Connection of machine tool. Before the assembly of all parts of the machine tool, remove the antirust coating on the installation connection surface, the guide rail and the surface of all moving parts, and do a good job in cleaning the appearance of all parts. Then assemble all parts of the machine into a whole machine, such as installing the column, numerical control cabinet and electrical cabinet on the bed, installing the manipulator of the tool magazine on the column, and installing the extension body on the bed. The original positioning pin, positioning block and positioning element should be used during assembly to restore the installation position to the state before disassembly of the machine tool, so as to facilitate the next step of precision debugging. After the components are assembled, the cables, oil pipes and gas pipes are connected. There are electrical wiring diagram and pneumatic and hydraulic pipeline diagram in the manual of the machine tool, so the relevant cables and pipelines should be connected one by one according to the marks. When connecting, pay special attention to cleaning, reliable contact and sealing, and check for looseness and damage. After the cable is inserted, the screw must be tightened to ensure reliable contact. In the connection of oil pipe and gas pipe, it is necessary to prevent foreign matters from entering the pipe from the interface, so as to avoid the failure of the whole hydraulic system. When connecting pipelines, each joint should be tightened. Otherwise, during the test run, especially on some large oil separators, if one pipe leaks oil, it is often necessary to remove a batch of pipes, resulting in heavy repair work. After the cable and oil pipe are connected, the pipelines shall be fixed in place, the protective cover shall be installed, and the neat appearance shall be ensured.
(3) The connection and adjustment of CNC system includes open box inspection, external cable connection, power connection, confirmation of setting, confirmation of input current, voltage, frequency and phase sequence, confirmation of machine parameters, etc.
(4) Power on test run.
(5) Machine tool precision and function debugging.
(7) Organize machine tool acceptance
Hardware parts processing is popular in many places, among which nut is one of the parts. Introduce the use and application of nut
Application of nut: it is suitable for fastening all thickness plates and pipes (0.5mm-6mm), convenient and firm; instead of traditional welding nut, it can make up for the defects of sheet metal, thin pipe welding, unsmooth welding nut, etc.
Type of nut: flat head small head hexagon and half hexagon rivet nut, with through hole, blind hole, knurled and no knurled. Also known as rivet nut, pull cap, instant pull cap, used in all kinds of metal plate, pipe and other manufacturing industries in the field of fastening.
The nut can solve the defects of metal sheet and thin pipe welding, the nut is easy to melt, the tapping internal thread is easy to slide and so on. 1、 Before entering the post, all employees should check whether their clothes meet the work requirements. Slippers, high-heeled shoes and clothes affecting safety are not allowed. Those with long hair should wear safety helmets. When working, keep the right posture, have enough spirit to deal with the work, if you find that you feel unwell, you should leave the job immediately and report to the leader. The operator must not operate in the state of irritability and fatigue, so as to avoid accidents and ensure operation safety.
Before working, check whether the moving part is filled with lubricating oil, then start and check whether the clutch and brake are normal, and idle the machine for 1-3 minutes. It is strictly forbidden to operate in case of mechanical failure.
When replacing the die, first turn off the power supply, and then start to install and debug the die after the punch movement department stops running. After the installation and adjustment, move the flywheel by hand for trial punching twice to check whether the upper and lower dies are symmetrical and reasonable, whether the screws are firm, and whether the blank holder is in a reasonable position.
It is necessary to wait for all other personnel to leave the mechanical working area and take away the debris on the workbench before starting the power supply to start the machine.
After starting, one person shall transport the materials and operate the machine. Other people shall not press the electric building or step on the foot switch board, nor put their hands into the working area of the machine or touch the moving parts of the machine with their hands. When the machine works, it is forbidden to extend the hand into the slider working area, and it is forbidden to take and place the workpiece by hand. The standard tools must be used when taking and placing the workpiece in the die. In case of abnormal sound or machine failure, turn off the power switch immediately for inspection.
When off duty, turn off the idle power, and sort out the finished products, leftover materials and sundries on the post to ensure the clean and safe working environment.
The above operating procedures must be observed consciously, do not operate in violation of regulations. In case of failure, cooperate with the maintenance personnel for maintenance. In case of accident, cut off the power supply immediately, keep on-site report to the factory and wait for treatment. All consequences caused by violation of operating procedures shall be borne by the parties concerned.
The common wear types in machining include running in wear, hard grain wear, surface fatigue wear, thermal wear, phase change wear and hydrodynamic wear.
Running in wear is a kind of wear under normal load, speed and lubrication, which develops slowly and has little effect on machining quality in a short time.
Hard grain wear is due to the parts themselves or from the outside into the machine tool hard particles, mixed into the processing area, by mechanical cutting or grinding, causing damage to the parts, which has a serious impact on the processing quality.
Surface fatigue wear is a kind of mechanical damage caused by micro cracks or pits under alternating load. This kind of wear is usually closely related to the pressure, load characteristics, parts material, size and other factors.
Hot wear refers to the phenomenon that the heat generated in the process of friction acts on the parts, such as tempering softening, burning and wrinkling. This kind of wear usually occurs in high-speed and high-pressure sliding friction, which is destructive and accompanied by accident wear.
Corrosion wear is a kind of chemical action, that is, chemical corrosion causes wear. When the part surface contacts with acid, alkali, salt liquid or harmful gas, it will be subject to chemical erosion, or the part surface combines with oxygen to form hard and brittle metal oxide which is easy to fall off and wear the part.
Phase transformation wear is a kind of wear caused by long-term work at high temperature, the grain of metal structure on the surface of the part becomes larger when heated, and the grain boundary is oxidized, resulting in a small gap, which makes the part fragile and wear resistance decreased. Hydrodynamic wear is caused by the impact of liquid or particles mixed in liquid on the surface of parts at a faster velocity.
The selection of rail vertical machining center should be suitable for the product
Each CNC machine tool rail track machining center 850 has limited performance and processing scope. Only in a certain processing condition can the best processing efficiency be achieved for the corresponding machining objects. When selecting the CNC machine tools, the computer gong must consider the advanced nature of CNC machine tools and the adaptability to product categories (product modification), and avoid numerical control as much as possible. It is uneconomical for large machine tools to process small parts and high precision machine tools to process ordinary precision parts, which should be avoided as far as possible.
In terms of specifications, specifications usually refer to the stroke range of 850 coordinate axis and the power of main motor of CNC machine tool rail vertical machining center. When determining specifications, the size distribution of workpiece should be comprehensively considered. Generally, the size of workpiece should be 100-200 mm larger than that of workpiece, There is a big gap between the size of the worktable and the stroke of the coordinate axis of CNC machine tools made by different manufacturers, which can be used as a reference in the selection.
Considering from the type of CNC machine tool, according to the different processing elements of the workpiece, the form of CNC machine tool is also different. For example, the box parts need to be processed around the hole system. At this time, the line rail vertical machining center 850 is not suitable. The horizontal machining center should be considered, and the rotary table should be configured, and the size of the table should adapt to the installation requirements of the workpiece In the machining of cavity parts, the elongation and deformation of the vertical axis of CNC machine tool after heating should be considered in the long-time machining of large parts. Under possible conditions, it is most suitable to select the full closed-loop control mode or the CNC machine tool with full closed-loop control only in the vertical axis.
The performance and processing range of each kind of CNC machine tool is limited. Only under certain processing conditions, the corresponding processing object can achieve the best benefit. When choosing CNC machine tools, on the one hand, we should consider the advanced nature of CNC machine tools and the adaptability to product categories (product modification). On the other hand, we should avoid the waste of large size and high accuracy of CNC machine tools. It is not economical for large machine tools to process small parts and high-precision machine tools for processing ordinary parts. Professional mold manufacturing enterprises should give priority to the selection of CNC milling machines with working bench to meet the requirements. The automatic tool change function has little impact on the processing process, while the automatic tool change function (tool magazine) of large CNC machine tools costs a lot. The cooling channel of plastic mold is usually deep hole (diameter 10-16mm, length 500-1200mm), with large processing capacity and vertical processing Center 850 is still not suitable, so special horizontal deep hole CNC drilling machine should be selected, which can complete deep hole processing tasks efficiently and automatically.
The selection of rail vertical machining center should be compatible with the product. How to realize “0” scrap in NC lathe processing? In the CNC lathe processing industry, the ideal goal of each manufacturer is zero waste manufacturing. In order to make supplementary adjustment or feedback control for CNC lathe processing equipment, the dynamic accuracy theory should be studied from the accuracy theory, including the evaluation of dynamic accuracy. This paper studies how to make full use of the measurement information to achieve zero waste production. Through the full use of 100% online measurement data, the dynamic characteristics of error distribution in the process of processing and measurement are analyzed, At the same time, according to the dynamic characteristics of machining error and the accuracy loss characteristics of sensor accuracy, as well as the product quality requirements and tolerance regulations, Dongguan CNC machining center gives the basic theoretical model of zero waste manufacturing, and makes full use of modern mathematical methods such as artificial neural network and genetic algorithm to accurately predict the machining quality, so as to achieve quality control in advance.
In the process of CNC lathe processing, the workpiece can be measured online or 100% detected, which needs to study the test equipment suitable for dynamic or quasi dynamic, and even can be integrated into the special test equipment of CNC lathe processing, so as to achieve real-time test. According to the test results, the process parameters are constantly modified, but in the process of achieving this goal, the role and significance of precision test technology is self-evident. The processing quality of parts and the assembly quality of the whole machine are related to the processing equipment, test equipment (non-standard parts processing) and the analysis and processing of test information. Therefore, zero waste production can be realized from the perspective of precision test To start, we need to consider some problems.
CNC precision mechanical parts, any kind of machinery and equipment are composed of many different small parts, each part plays a crucial role. Parts need to be assembled, so precision machinery parts processing manufacturers will carry out reprocessing according to this demand. After processing various parts, we can get more suitable parts. Therefore, in order to make these products serve us better, many people can’t do without precision machinery processing. In order to ensure the precision of precision parts processing, rough and fine mechanical parts processing is best carried out separately. Because of the large amount of cutting, the cutting force and clamping force on the workpiece are large, and the heat value is high, and the obvious work hardening phenomenon on the machined surface of the mechanical parts, there is a large internal stress in the workpiece. If the rough and rough mechanical parts are processed continuously, the precision of the finished parts will be lost quickly because of the redistribution of the stress.
The heat treatment process is often arranged in the process route of CNC precision parts. The location of heat treatment process is as follows: in order to improve the cutting performance of metal, such as annealing, normalizing, quenching and tempering, it is generally arranged before the machining of mechanical parts.
CNC precision parts of the processing process is very strict, feed, out of the tool linked. Grasping the precision of the size can reduce the material loss and reduce the cost. For example, 1 mm plus or minus how many microns and so on, if the size is wrong, it will become a scrap, and the parts can not be used.
Research on key technology of design and manufacture of continuous fine blanking die for complex parts
The continuous fine blanking die for complex parts is the frontier basic technology of fine blanking technology, and it is expected to promote the whole fine blanking technology in China. Taking the synchronizer gear ring, clutch plate, longitudinal compound continuous fine blanking process and continuous fine blanking die for complex parts as the breakthrough point, the key technology of fine blanking die design and manufacturing is studied, so as to realize the rapid improvement of fine blanking die technology in China and shorten the gap with advanced countries as soon as possible.
Die life is a comprehensive reflection of die material, process and supporting product level. Taking die life of fine blanking as the leader to carry out technical research can not only solve the problem of low die life which is urgently needed in China, but also drive the technological development of die material, fine blanking process, supporting tooling and other auxiliary products.
Precision blanking and precision forging are two advanced manufacturing technologies developed in parallel. If the precision blanking parts are too thick and need precision forging, the precision forging must be too thin. They are closely related. The basic idea of developing precision forging and fine blanking compound process is to find the combination point of the two processes (such as gear parts with wheel hub and cam parts with short shaft). The precision forging in China has a long history and has a high level, so it is a good way to improve the overall level of precision blanking technology in China