Analysis and processing of four axis machining: the alarm may be caused by the poor SQL3 of the table loosening position sensor or the CNC did not receive the clamping signal of the turntable, because similar faults occurred before were caused by poor plug contact. To confirm, open the side cover of the turntable, and close a small saw blade to the end of SQ13: the SQL3 lamp is on, which proves that SQL3 is normal. Meanwhile, the data of PLC and ladder iaxbul can be highlighted, indicating that the system can receive signals. Therefore, it is suspected that there are problems in the hydraulic part, such as insufficient hydraulic pressure, oil leakage of hydraulic cylinder rising the turntable, mechanical stagnation when the turntable rises, which makes the turntable rise not in place. The hydraulic pressure of four axis machining is checked. When the machine stops moving, the pressure is 5.5mpa. When the turntable or machine is manually operated, it is found that the pointer of the system pressure gauge is shaking obviously and the hydraulic pump has obvious noise. Therefore, it is suspected that the hydraulic pump inhales air: check the oil level of the oil tank and find that the oil tank is empty. After filling the tank, turn the turntable again, normal. The variable pump is used to supply oil in the hydraulic system. When the hydraulic pressure is not operated, the system keeps pressure, the hydraulic pump absorbs less oil, and the oil level of the oil tank basically meets the requirements. When the hydraulic pump is operated, the hydraulic pump shall supply oil. Because the oil tank is not enough, the system pressure is insufficient, which leads to the failure of the turntable to rise in place. Half an hour later, the machine alarm again, and then look at the oil level, and the oil is gone, indicating that the hydraulic system leaks oil: finally, it can find the oil pipe of the turntable rising is broken and leaking; after replacement, the fault is completely eliminated.
CNC machining of revolving parts
CNC lathe machining center is a common name of CNC lathe. The key difference between turning and milling is that it is mainly used for the machining of rotary parts such as shafts, ring parts, disk parts and threads.
CNC lathe can be divided into horizontal CNC lathe and vertical CNC Lathe according to spindle configuration. There are many kinds of horizontal CNC lathe. The function of early CNC lathe is relatively simple, only x, Z axis linkage function to achieve digital control turning processing. Based on the need of expanding the processing range on the CNC lathe, the power tool is added to the tool holder of the NC lathe, and the milling function is increased. On this basis, the turning and milling machining center is developed. However, the processing range of the traditional turning and milling machining center is limited due to the fact that the cutting tool of the CNC lathe always faces the rotation center of the spindle Drilling, reaming, reaming, etc. toward the spindle rotation center. With the continuous development of numerical control technology, as well as the requirements of new product development and rapid response, the main structure of CNC equipment forms serialization and modularization, increases Y-axis and its rotation axis, and develops into a real turning and milling machining center.
As one of the important parts of CNC lathe, the turret determines the overall layout and working performance of CNC lathe. There are turret turret and linear array turret. Turret turret is the most common horizontal CNC lathe.
Numerical control lathe is very popular in the factory, and it plays an important role in the field of processing as the machining center. Industrial statistics show that CNC lathes are generally considered to be relatively simple compared with machining centers, although CNC lathes can produce high-quality parts. CNC lathe is mainly used to process high-precision, good surface quality requirements of rotary parts, so it needs few programs and start-up operation, but this does not mean that CNC lathe can not be used for processing short cycle and ordinary parts, just because the ratio of parts to be machined by turning is much higher than that by milling.
- Characteristics of CNC lathe
(1) CNC lathe can automatically complete the following operations: spindle speed change, forward and reverse rotation, start or stop, feed and rapid movement in two coordinate directions, release, rotation and clamping of tool rest, switch of cutting fluid, etc.
(2) The feed of NC turning tool must be connected with the rotation of the spindle, because the turning of NC lathe is calculated by the number of pulse equivalent that the turning tool moves along the feed direction when the spindle rotates a circle.
(3) Since the dimension marking and measurement of part design drawings are diameter values, in order to improve the accuracy of radial dimension and facilitate programming and measurement, X-direction pulse equivalent is taken as half of Z-direction, so when the diameter direction is programmed with absolute value, x-coordinate value is expressed as diameter value. When using incremental programming, the program is programmed by twice the actual radial displacement, and the direction symbol is attached.
(4) When machining parts with horizontal CNC lathe, based on the needs of surface quality and machining accuracy of the parts, the spindle must have a large speed range, which can adopt either constant surface speed or constant speed.
(5) It has the function of tool compensation and skip instruction.
(6) CNC lathe is usually a two coordinate machine tool, which can realize two coordinate (x, z) linkage processing of revolving body contour parts.
(7) Due to the large machining allowance of blank and die forging, CNC lathe often has different forms of fixed cycle function, which can carry out a variety of turning cycles
CNC computer gongs thread milling method
CNC computer gong processing needs to be proficient in horizontal processing, and large gantry (moving beam, top beam) processing. Must have good fixture foundation and measurement technology level. The difficulty of fixture analysis is that it can only be qualitative and difficult to quantify. The operation also pays attention to the handle.
In the CNC computer gongs processing process, there is a method called thread milling method, which specifically refers to it? Thread milling is to use thread milling tool, machining center three axis linkage, namely x, Y axis arc interpolation, Z axis linear feed milling method.
Thread milling is mainly used for machining large hole thread and thread hole of difficult to machine material. It has the following characteristics:
(1) high speed, high efficiency and high precision. The material is generally cemented carbide material, and the cutting speed is fast. The manufacturing precision of cutting tool is high, so the precision of thread milling is high.
(2) milling tools are widely used. As long as the pitch is the same, whether it is * * thread or right-hand thread, one tool can be used, which is conducive to reducing the cost of the tool.
(3) milling is easy to chip removal and cooling. Compared with the tap, the cutting condition is better. It is especially suitable for the thread processing of difficult to machine materials such as aluminum, copper, stainless steel, etc., especially for the thread processing of large parts and components of valuable materials, which can ensure the quality of thread processing and the safety of the workpiece.
(4) because there is no tool front-end guide, it is suitable for machining blind holes with short thread bottom holes and holes without undercut groove
Computer gong processing parameters
The gear parameters of the front center are: modulus M = 4, number of teeth z = 9, addendum height coefficient ha = 1, addendum clearance coefficient C = 0.25, radial modification coefficient X = 0.4, number of teeth across k = 2, common normal line wn = 19.5 + 0.2 + 0.1 (mm). CAXA does not provide professional gear modeling command, and can model through function curve, but this method is cumbersome and more difficult to model with modification coefficient.
It is not easy to ensure the size of the curve groove at the lower end of the front of the part, and the two 90 ° gaps are not closed. It is necessary to do auxiliary line closure before programming.
There are two ellipses with different directions on the inner contour edge of the back, the inner and outer hexagonal petals formed by arc, and two arc curve islands on the upper and lower sides. These elements need to be rounded in the processing, so it is more convenient to choose a reasonable shape.
1、 Analysis of parts processing technology
When CAXA is used to manufacture engineering parts, there is no need to draw complete parts for reprocessing. Firstly, the downtime is long and the processing time is wasted. Secondly, when selecting local processing, the elements of parts will interfere, which makes it inconvenient to get the program path.
When machining plane contour elements, the software supports only drawing out the contour line of parts for rough and finish machining. Surface machining can be programmed by solid or surface machining. Surface must be used to realize local machining, and some finishing commands can only use curved surface to select machining.
The rough machining command can not only realize rough machining, but also be used as finishing command.
The finishing command can use the track translation to form multiple levels, and the connecting track becomes a whole rough machining command; the rough machining command can change a layer of machining track into a finishing command by setting the layer height.
The plane contour elements of “CAXA Manufacturing Engineer” can use plane area rough machining and contour line finishing to finish the rough and finish machining of parts, and can also use contour finishing to do rough machining. Surface roughing can use equal height rough machining, or two finishing commands of parameter line finishing and three-dimensional offset surface for rough and finish machining.
Due to the high dimensional accuracy in the drawing, it is decided to use rough machining, semi finishing and finishing to achieve dimensional accuracy. Semi finishing and finishing use the same cutting tool and cutting parameters, which can correct various geometric errors of the cutter and elastic deformation of parts, and ensure the size easily. It is also necessary to finish the important bottom surface.
The part is processed by FANUC CNC machining center. All tool paths are generated according to FANUC post format, and the transmission uses CAXA’s own communication function according to FANUC settings. The larger surface program is processed online. The later processing programming ends with tool path. 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 ensures the accuracy of plane and hole orientation, and brings convenience to the processing of holes on the plane.
2、 Machining datum plane first
In the process of parts processing, the surface as the positioning reference should be processed first, so as to provide the precise reference for the subsequent processing as soon as possible. It is called “benchmark first”.
3、 Finishing
The finishing of the primary surface (such as grinding, honing, finishing grinding / rolling, etc.) should be carried out at the final stage of the process road. After processing, the surface finish should be above ra0.9um, and slight bumping will damage the appearance. In Japan, Germany and other countries, after finishing, it is necessary to use flannelette for maintenance. It is absolutely forbidden to touch the workpiece directly with hands or other objects to avoid polishing The appearance of the finishing process is damaged by the transfer and installation between processes.
4、 Distinguish processing stages
The appearance with high machining quality is divided into three stages: rough machining, semi finishing and finishing. The first is to ensure the quality of processing; it is conducive to the rational use of equipment; it is convenient to organize the heat treatment process; and it is convenient to find the defects of the blank.
Positioning accuracy of computer gong processing
The positioning accuracy is about 10 μ M. High precision machining center, resolution of 0.1 μ m, maximum feed rate of 15 ~ 100M / min, positioning accuracy of about 2 μ M. In the range of 2-10 μ m, the more is ± 5 μ m, which can be called precision grade.
NC machining center NC edit NC machining center is a kind of CNC machine tool with tool library and automatic tool change, which can carry out a variety of processing operations on the workpiece in a certain range.
The characteristics of machining parts on the machining center are: after the machined parts are 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, motion track of the cutter relative to the workpiece and other auxiliary functions, and automatically drill, countersink, ream, bore and screw on each machining surface of the workpiece Multi process processing such as grain, milling, etc. 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.
Performance of computer gong deep hole drilling machine
The computer gong processing deep hole drilling machine is different from the traditional hole processing method. The computer gong processing mainly relies on the specific drilling technology (such as gun drill, BTA drill, spray drill, etc.), and the special machine tool for drilling the deep hole system with the length diameter ratio greater than 10 and the precision shallow hole is collectively referred to as the deep hole drilling machine. It has the following five characteristics in practical application
- The casting of the whole machine is made of high-quality mihanna cast iron, and the aging treatment makes the casting structure uniform and stable, high rigidity and good stability.
- Three coordinate deep hole drilling machine adopts imported high rigidity and high-speed CNC to process high-precision screw rod, which can provide more powerful torque and be more durable.
- High quality servo motor and driver are used for three-dimensional feed drive, and they are directly connected with ball screw. Mechanical parts are processed and transmitted smoothly without backlash. At the same time, its good rigidity and optimized shock absorption performance greatly improve the dynamic rigidity of the transmission system and realize rapid movement.
- The main shaft adopts powerful motor, which can meet the processing requirements of high and low speed. CNC machining and automatic oil cooling system ensure the constant temperature during processing.
- The operating system adopts Taiwan system, which can be compatible with CAD / CAM software and can be more diversified.
CNC machining – boring
1 tool rotation
Different from lathe processing, because of tool rotation in machining center, it is impossible to master the situation of tool tip in time to adjust the feed rate. It is impossible to change the machining diameter just by adjusting the NC button like the NC lathe. This has become a big obstacle to fully automated processing. Because the machining center does not have the function of automatic diameter adjustment (except for those with U-axis function), the boring cutter must be equipped with fine adjustment mechanism or automatic compensation function, especially in fine boring, sometimes it must be adjusted at micron level according to tolerance requirements.
When machining center boring, because the direction of chip outflow is constantly changing, it is much more difficult to cool the tool tip, workpiece and chip discharge than when machining with a lathe. Especially when the longitudinal machining center is used for rough boring of steel blind hole, this problem has not been completely solved.
2 chatter
Chatter is the most common and headache problem in boring. The main causes of chatter on machining center are as follows:
① Rigidity of tool system: including the rigidity of toolholder, boring bar, boring head and intermediate connecting part. CNC machining is a kind of cantilever machining, so the rigidity of tool system is very important, especially when machining small holes, deep holes and hard workpieces.
② Balance of tool system: relative to the rotating axis of the tool system, if there is an unbalanced mass of the tool itself, the chatter will occur due to the action of unbalanced centrifugal force during rotation. Especially in high speed machining, the dynamic balance of the tool has a great influence.
③ Clamping rigidity of workpiece itself or workpiece: for example, some small and thin parts cannot be fully fixed with reasonable fixture due to insufficient rigidity or workpiece shape.
④ Geometry of edge: different rake angle, escape angle, nose radius and chip breaking groove shape have different cutting resistance.
What we call boring in CNC machining center is to enlarge or refine the original hole on the workpiece. The feature of CNC machining is to correct the eccentricity of the lower hole, obtain the accurate position of the hole, and obtain high-precision roundness, cylindricity and surface finish. Therefore, boring as a high-precision machining method is often used in the final process. For example, the bearing holes of various machines and the processing of boxes and covers of various engines.
Compared with other machining, boring is a difficult process. It only needs to adjust one blade (or blade holder) to process micron sized holes such as H7 and H6. With the popularization of machining center, the boring process only needs programming and button operation. Because of this, it is necessary to have simpler, more convenient and more precise cutting tools to ensure the quality of products.
Computer gong – manual adjustment of spindle
Computer gongs processing in the center can complete milling, boring, drilling, expanding, reaming, tapping and other programs of a variety of processing, the process is highly concentrated. The machining center is equipped with a tool magazine and an automatic tool change device. CNC machining will load the required tools into the tool library before processing, and the tools can be changed automatically through program control. If the machining center is equipped with automatic exchange worktable, it can realize that one worktable can complete the clamping of workpieces at the same time of processing, thus greatly reducing the auxiliary time of processing and improving the processing efficiency.
The commissioning of vertical center should follow the following steps:
- According to the requirements of the manual, oil the lubrication points of the vertical machining center, fill the hydraulic oil tank with the required hydraulic oil, and connect the air source.
- Power on the vertical center, supply power to each component separately or after one power on test, the high-speed computer gongs process and then fully supply power. Observe whether the components have alarm, whether the manual operation parts are normal, whether the safety devices work, so that all links of the machine tool can operate and move.
- After the initial operation of the vertical machining center, the geometric accuracy of the machine tool is roughly adjusted, and the relative position of the main moving parts and the host machine after disassembly and assembly is adjusted. The manipulator, tool magazine, exchange table, position alignment, etc. After the mechanical parts are processed, the anchor bolts of the main engine and accessories can be filled with quick drying cement, and the reserved holes of the foot bolts at all places can be filled and leveled.
- The worktable of the vertical machining center is moved to the exchange position, and the relative position of the pallet station and the exchange table is adjusted, so that the automatic exchange of the worktable is stable, and the maximum load of the worktable is installed for multiple exchanges.
- Debugging, prepare various testing tools, such as standard square, precision level, parallel square tube, etc.
- Adjust the position of the manipulator to the spindle by manual operation. When the tool holder with the maximum weight is installed in the mold, the automatic exchange between the tool magazine and the spindle position should be carried out for many times to ensure the accuracy and no collision.
- Fine adjust the level of the machine tool, so that the geometric accuracy of the vertical machining center can reach the allowable error range. The multi-point cushion support is used to adjust the bed to the level under the free state to ensure the stability of the bed after adjustment.
- Check whether the setting parameters of the CNC system and PLC device conform to the specified data in the random data, and then test the main operation functions, safety measures and the execution of common instructions.
CNC machine key function
There are two lights on the power supply of CNC machining center unit, one is the power indicator, which is green; the other is the power alarm light, which is red. The power supply unit here includes the power input unit and the power control part.
First of all, we should know that when the CNC computer gong machining center power can not be connected, if the power indicator (green) is not on. The fuses F1 and F2 of the power supply unit have been blown. This is due to high input voltage, or the components of the power supply unit itself have been damaged.
The input voltage of CNC computer gong machining center is low. Please check the voltage entering the power supply unit. The allowable voltage value is AC 200V + 10%, 50 Hz ± 1Hz. The power supply unit is not good, there is element damage in it. The power indicator light is on, and the alarm light is also gone, but the power supply cannot be connected. This is because the power on condition is not satisfied. By the following switching circuit, the power supply conditions are as follows:
CNC machining center power supply has three conditions: the first point, the source on button closed. Second, the power off button is closed. Third, the external alarm contact is opened.
The alarm light of power supply unit of CNC machining center is on: the fuse of 24 V output voltage is fused, and + 24 V voltage is used on 1.9 “display screen, as shown in the figure below. Check whether + 24 V is short circuited to the ground. 2. The display / manual data input board is poor. During the use of the center, the tool imbalance may occur. If not adjusted in time, it will affect the processing effect. Therefore, we should always pay attention to the tool balance of CNC machining center. What are the main reasons for the imbalance of the handle?
The main reason for CNC machining is that the tool design is asymmetric, there are defects in the tool body, and all the adjustment of the tool. The correct balance of the tool can significantly reduce noise and vibration, which increases the tool life and improves the accuracy consistency of parts.
The centrifugal force of CNC machining center is proportional to the square of velocity to amplify the vibration caused by unbalance. As a result, the vibration of CNC machining center increases, which minimizes the service life of bearing bush, bearing, shaft, spindle and gear.
Before balancing the tool in CNC machining center, it is necessary to measure the unbalance and the angle position of each selected correction plane. These variables are measured on two general types of balancing machines: non rotating or gravity machines are used to measure single plane unbalance, while rotary or centrifuge is used to measure single plane or two plane unbalance.
After measuring the magnitude and angle of the unbalance in the correct plane, you can correct it by adding or removing material from the workpiece. For the components which are not tools, the most widely used material adding method of drilling center is welding counterweight on the components.
CNC machining (CNC machining) refers to the processing with CNC machining tools. The index controlled machine tool is programmed and controlled by NC machining language, usually G code. NC machining G code language tells CNC machine tool which Cartesian position coordinates, and controls the tool feed speed and spindle speed, as well as tool converter, coolant and other functions. Compared with manual machining, CNC machining has great advantages, such as the parts produced by CNC machining are very accurate and repeatable; CNC machining can produce parts with complex shapes that cannot be completed by manual processing. CNC machining technology has been widely promoted, most of the machining workshops have the ability of NC machining. The most common NC machining methods in typical machining workshops are CNC milling, CNC lathe and CNC EDM wire cutting (WEDM). The tool for NC milling is called CNC milling machine or CNC machining center. CNC turning lathe is called CNC lathe center. NC machining G code can be manually programmed, but usually the machining workshop uses CAM software to automatically read CAD file and generate G code program to control NC machine tool.
Computer gong processing – Measurement
3.2. Inspection standards before processing:
3.2.1. Divide the center and read the number. After each division, copy the working coordinates first, and then check again whether the distance from the center to both sides is consistent, to ensure that the center and reading are correct.
3.2.2. Tool selection, tool loading, tool setting and z-axis coordinate reading.
Select the appropriate tool according to the programming list. Clean the cutter head and nozzle thoroughly before installing the tool. After installing the tool, use the calibration table to check whether the tool has deflection. It is necessary to check again after the tool is set and the number is read, so as to avoid the wrong knife, which will bring great loss to the company.
3.2.3. transport program, start processing: before cutting, use single section execution, transfer speed and feed speed to the slowest, slow down the knife, watch the machine tool display Z axis allowance, check whether there is abnormal, if abnormal, press the pause button immediately, find out the reason to solve the anomaly, confirm that after normal, adjust to the right speed to start processing.
3.2.4. In the process of processing, always pay attention to observe whether the processing is abnormal and whether the tool is worn. If the tool wear is serious, the tool grinding shall be suspended to ensure the normal processing.
3.3. Mold kernel processing standards
3.3.1. After getting the drawing and workpiece, check whether the drawing is consistent with the die number of the workpiece.
3.3.2. Measure the actual size of the workpiece with measuring tools.
3.3.3. Check whether the direction of water transportation and reference angle on 2D drawing is consistent with that on the programming list.
3.3.4. Remove the rough edges at the bottom and around the workpiece with a 400 ා oilstone, and wipe the workpiece with cloth scraps.
3.3.5. Place the workpiece on the clamping tool of the machine platform, level the workpiece plane and perpendicularity with parallelism, and the perpendicularity tolerance is within ± 0.015,
Then fix the workpiece firmly and start to divide according to the position marked on the programming list and the size of z-axis collision. (pay attention to whether the edge finder collides with the workpiece during the separation) input the data of the mechanical coordinates x, y, Z into the corresponding coordinates.
3.3.6. According to the programming list, transfer all programs into the computer, simulate with the tool path simulation software, observe the processing area and the highest and lowest depth of processing, and determine the clamping direction, clamping reserved position and tool length of the workpiece.
3.3.7. Install the corresponding tool according to the programming list, and input the tool parameters automatically with the method of automatic tool setting.
3.3.8. Transfer the program to the machine for processing.
3.4. Copper processing standard
3.4.1. After getting the program sheet, find the appropriate copper material according to the mold number, size and quantity of copper on the program sheet.
3.4.2. According to the requirements of the programming list, process the coarse and young products. (the copper material is marked with a code, “a” stands for Yougong, and “B” for coarse material.
3.4.4. Check whether the tool on the program list is consistent with the tool on the machine tool magazine.
The program is simulated with tool path simulation software to observe the processing area and the highest and lowest machining depth to determine the clamping direction, reserved position and tool length of copper male.
3.4.5. Transfer the program to the machine for processing. The workpiece must be prepared for the next machine in the processing, so as to reduce the above preparation time.
3.5. Formwork processing standards
3.6.1. After the workpiece is processed, check whether the shape of the workpiece is consistent with that of the 3D drawing before getting off the machine, and then check whether the workpiece has missed processing, over cutting, and the position of joint connection.
3.6.2. According to the data marked on the programming list, use the calibration table or depth meter to measure the number, and use the needle gauge or plug gauge to measure some matching positions and positioning positions.
3.6.3. Parting surface measurement: according to the data provided by drawings or programmers, detect the coordinates of points (x, y, z) on several parting surfaces, and check whether the parting surface has been processed to the number.
3.6.6. Measure whether the depth of all flat positions reaches the number. For some positions that need to be connected smoothly, the processing shall be improved first, and then the connection shall be carried out slowly after painting the color on the connecting position.
3.6.7. Check all other position data that require CNC machining accuracy and confirm that it is OK before getting off the machine.
3.7 precautions:
3.7.1. Be careful when taking out the tool from the tool holder to avoid scratching fingers.
3.7.2. Do not allow the machine to run fully automatically when using the NC program that has not been tried out.
3.7.3. When the shaft is still rotating, adjust the coolant flow direction with great care.
3.7.4. In case of emergency, press the red emergency button on the controller.
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