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CNC machining center spindle fault

The spindle is the power auxiliary device of CNC machining center. The spindle drives the workpiece to rotate to process the workpiece of the rotating body. Spindle is an important guarantee for high-speed and high-precision machining of CNC machining center, so the maintenance methods and skills of spindle fault are the basic knowledge that operators and maintenance personnel of CNC machining center must master. In the operation of CNC machining center, the spindle will inevitably have some faults. What is the specific reason?

Different types of CNC machining centers adopt different types of spindles. According to the different transmission systems, the spindle system can be divided into the main transmission spindle with variable speed gear, the main transmission spindle with belt transmission, the dual motor drive spindle and the motor spindle integrated spindle. No matter what type of spindle application, the common faults in use are as follows:

Overload.

Fault causes: excessive cutting amount, frequent forward and reverse rotation, spindle motor fault, spindle drive device fault.

The spindle does not rotate

Fault causes: spindle drive failure, CNC device can not output speed signal, spindle motor failure, spindle drive failure, drive belt fracture.

The spindle speed deviates from the command value

Fault causes: motor overload, CNC system output spindle speed command output problem, speed measuring device failure or speed feedback signal disconnection.

Mold maintenance mode

Management of mold field use

Dispatchers should go through relevant procedures according to the corresponding management system when collecting and returning the molds, and be responsible for the whole process of the molds from receiving to returning.
The die should be processed according to the stamping process and the corresponding tonnage of punch press. The mold should be adjusted and installed by the mold adjuster, and ensure that the leakage is smooth, the spring top is normal, the feeding is convenient, the stroke is reasonable, and the production can be started after the qualified sample is tested.
The punch operator shall strictly follow the operation procedures. If any abnormal phenomenon is found in the production process, it should be reported in time, and the production can be carried out after troubleshooting. In case of mold damage caused by barbaric operation, the responsible person shall fill in the mold accident liability sheet and give certain punishment.
In case of die waste fracture, guide plate guide deformation, die and punch damage caused by pressing and bending die stuffy, it is necessary to trace the responsibility of the adjuster.
The usage of the mould shall be clear during the shift handover of day shift and night shift. The successor shall be responsible for the accident after the handover.
After the completion of the production task, the dispatcher shall be informed in time to handle the warehouse return procedures. The production site should not keep the mold without production instructions or complete the batch task. If the mould is lost, the responsibility of the final receiver will be traced.

Purpose of mold maintenance system

Master the history of the mold 2. Maintain the mold in time after mold production 3. Improve the service life of the mold 4. Ensure the quality of the mold and smooth production

Mold maintenance mode mold maintenance is divided into four modes

Preventive inspection: take every 15 days as a cycle to check the mold status directly on the production machine, and record the results in the “mold preventive inspection record form”. This part of the inspection is in the charge of the mold group, assisted by the injection molding department.
General maintenance (A-level maintenance): it refers to the general maintenance items of the mold during the daily mold test and trial production, which are responsible and recorded by the production department.
Regular quantitative maintenance (B-level maintenance): when the mold has not been used for more than one year or has accumulated more than 50000 beer each time, detailed inspection shall be carried out, and the inspection results shall be recorded in the “mold maintenance inspection record form”. The production department is responsible for and records.
Mold maintenance (C-level maintenance): when the injection molding material has serious appearance problems or the mold is damaged, the parts need to be replaced or repaired.

The motor does not run;

Switching power supply (± 15V) transformer TL and power switch tube v69 are abnormally hot.

This is a typical case of syndrome, and there may be some causal relationship between the faults, so we need to deal with the faults in sequence, otherwise we may get twice the result with half the effort, or even cause the fault area to expand. Through the analysis, we make the following maintenance order: switching power supply one > under voltage light > motor running. Firstly, check the power supply board. After measuring the 150V DC voltage of the main circuit and disconnecting the ± 15V load, we know that the fault is inside the switching power supply board. In the check of the power supply board, we find that the voltage of the 10V regulator V32 is only 9.5v. From this, we can find the cause of the fault: the current limiting resistance rl85 of V32 becomes larger. After replacing rl85, the ± 15V power board and “under voltage” lamp returned to normal, but the motor still did not run. It can be seen that the above flashing lights and hot components are caused by rl85 variation, and there is another reason for the motor not running. According to the usual inspection method, it can be detected step by step, but due to experience, we only did a simple transformation and steering test, and found that the reverse operation was normal, so we quickly found out the cause of the fault: the integrated block N5 (tl084) of the commutation circuit failed, and everything was normal after replacing N5

PC interface method

Because the signal transmission and control between each unit (except driver) of NC machine tool and NC system are realized through PC interface (1 / O), many faults will be reflected through PC interface signal. We can diagnose various complex machine tool faults or judge whether the fault is in NC system or in machine tool electrical by consulting 1 / O signal of PC machine tool side. The method is very simple, that is, it is required to be familiar with the current state and normal state of all PC (machine side) interface signals (or make a table). During diagnosis, check and compare the current state and normal state of all PC (machine side) interface signals one by one to find out the faulty interface signals, and then find out the fault causes according to the external logic relationship of the signals. When you are familiar with the PC interface signal, the application of this PC interface comparison method is very simple and fast, and avoids the complicated ladder program.

Recovery of abnormal data in Siemens 3GG system

The grinder s45-6 of Switzerland is equipped with Siemens 3GG system, which is a dual n C dual PLC structure. The system has a strong self diagnosis function. When a fault occurs, it can quickly diagnose and repair the fault with the help of the screen prompt. However, if the system cannot be started, and the PLC is in the stop state, the screen is not bright, then the self diagnosis function of the system will not play a role, leading to the difficulty of diagnosis. If the battery voltage is lower than 2.7V, the battery must be replaced; if the NC or PLC hardware is damaged, the circuit board needs to be replaced; if the 24 V power supply of the machine tool is lower than 21 V, the power supply circuit and load need to be checked.

But we encounter more faults, the reason is not the hardware fault, but the machine data abnormal such as soft fault. The reasons are complex, such as power grid interference, electromagnetic wave interference, battery failure, operation error and so on, which may cause the loss or confusion of machine data, so that the system can not start.

Abnormal noise of spindle in CNC machining

Cause of failure: it usually occurs in the process of deceleration, and there is something wrong with the spindle drive device, such as the regeneration circuit fault in AC drive.

CNC machining center spindle abnormal noise is most operators will encounter things, understand the cause of the failure, we should take what measures to solve it?

When the machining center is in use, some customers often find that the spindle is transported by belt. After a long time of use, there will be abnormal noise. When the forward transmission and reverse transmission are switched, there will be noise. According to years of assembly experience, it is determined that most of the problems are caused by the belt, The belt tension at the joint of servo motor and spindle is too tight, which leads to the phenomenon of belt slipping, so the spindle will make abnormal noise.

Another situation is that the tension of the belt connecting the servo motor is not enough, so it will appear that the belt of the motor is too loose, which can be seen intuitively. When the machining center is used for heavy chip, it will slip and make abnormal noise. After the machining center is used for a long time, the belt will be worn, which is part of the cause of abnormal noise.

After the abnormal noise of CNC machining center spindle occurs, some economical customers will choose to replace the drive wallet. After the replacement, the belt drive gear and the tooth profile of the motor and the spindle do not match, and they can make do with it. However, there will be a lot of abnormal noise during use, which seriously causes the wear and damage of the gear of the servo motor and the spindle. It is suggested to observe whether the belt model purchased is the same as that replaced. Spindle is an important guarantee for high-speed and high-precision machining of CNC machining center, so the maintenance methods and skills of spindle fault are the basic knowledge that operators and maintenance personnel of CNC machining center must master. In the operation of CNC machining center, the spindle will inevitably have some faults. What is the specific reason?

Overload.

Fault causes: excessive cutting amount, frequent forward and reverse rotation, spindle motor fault, spindle drive device fault.

The spindle does not rotate

Fault causes: spindle drive failure, CNC device can not output speed signal, spindle motor failure, spindle drive failure, drive belt fracture.

The spindle speed deviates from the command value

Fault causes: motor overload, CNC system output spindle speed command output problem, speed measuring device failure or speed feedback signal disconnection.

Abnormal noise and vibration of spindle

Computer gong processing tool

The main matching dimensions of parts are guaranteed by computer processing, so 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.

The four corners of the tool should be the same height.
A is higher than D.
The forward (tool face) of the tool is higher than the back, that is, it has a certain back angle.

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:

Program name
Tool size and length
Method of machining tool path
Machining allowance
Rough or light knife

Key points of complex parts processing

The continuous fine blanking die for complex parts is the frontier basic technology of fine blanking technology. Taking this as the leader, the research is expected to promote the whole fine blanking technology in our country. Taking the synchronizer ring, clutch plate, longitudinal compound continuous fine blanking process and die for complex parts as the breakthrough point, the key technology of fine blanking die design and manufacturing is studied, and the development of fine blanking die technology in our country is realized The gap between China and advanced countries should be shortened as soon as possible.

Study on the life promotion of fine blanking die and its related key technologies

Die life is a comprehensive reflection of die material, small process and supporting product level. Taking the life of fine blanking die as the leader to carry out technical research can not only solve the problem that the life of fine blanking die is too low, but also drive the technical development of die material, fine blanking process, supporting tooling and other auxiliary products.

Research and development of fine blanking precision forging composite technology

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.

Computer gong processing vertical processing

The height of the vertical machining center is limited, which reduces the processing range of the workpiece, which is the disadvantage of the vertical machining center. However, the workpiece clamping and positioning is convenient for vertical machining center; the cutting path is easy to observe and debug, the program inspection and measurement is convenient, the problems can be found in time, and the treatment or modification can be stopped; the cooling conditions are easy to establish, and the cutting fluid can directly reach the cutting tool and machining on the surface; the three-axis and Cartesian coordinate system, intuitive feeling, conforms to the design point of view, and the chip is easy to eliminate, Surface treatment to avoid scratches.

Vertical machining center

Mainly used for:

Using grease and oil circulation in machining center will produce abnormal heating.
Spindle, need high-definition washing, high-speed bearing sealing place

working principle:

The use of compressed air flow pipe, transmission oil along the pipe caused by continuous flow, stirring and transportation of oil and gas processing center spindle part and other parts of the screw need lubrication. The constant pressure dry compressed air (bar) 5 – 8 continuous supply, according to the spindle and lubricating oil lubrication, screw oil and other parts of the fuel consumption different quantitative supply. Therefore, each lubrication circuit must use a separate micro pump power supply of oil. After the oil pump, it must enter the oil and natural gas mixing valve. In the oil and natural gas mixing valve, the compressed air flow blows into small oil drops and adheres to the wall to form an oil film. The flow direction of the air flow between the oil film and the pipe wall, and the thickness of the medium oil film gradually becomes thinner, but not together.

CNC machine tool processing principle, all kinds of processing tools, all kinds of workpiece processing tool path method, all kinds of workpiece feed and speed, cutting amount.

Maximum depth allowed for each cutting, actual m auxiliary function, s speed, t tool change, R radius, u, W are relative G: preparation command M: auxiliary command T: tool s: spindle speed, R: arc radius, and then p q R, where R means different.

Method of reducing error in computer gong processing

After the workpiece is placed on the pad iron, it is necessary to pull the table for the workpiece datum according to the drawing requirements. For the workpiece that has been ground on six sides, it is necessary to check whether its verticality is qualified.

The nut must be tightened after the work-piece is pulled to prevent the work-piece from shifting during the processing due to the loose clamping; pull the work-piece again to ensure that the error does not exceed the tolerance after the clamping.

Number of workpieces touched

For the clamped workpiece, the contact head can be used to set the processing reference zero position. The contact head can be used in photoelectric type and mechanical type. There are two kinds of methods: middle collision number and unilateral collision number

Photoelectric static, mechanical speed 450 ~ 600rpm. Manually move the x-axis of the worktable according to the collision number to make the collision number head touch one side of the workpiece. When the collision number head just touches the workpiece and the red light is on, set the relative coordinate value of this point to zero. Then manually move the x-axis of the worktable to make the collision number head touch the other side of the workpiece. When the collision number head just touches the workpiece, record the relative coordinate at this time.

According to the relative value minus the diameter of the collision head (i.e. the length of the workpiece), check whether the length of the workpiece meets the requirements of the drawing.

What is the benchmark of computer gong processing

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.

The movement of the workpiece and the movement of the tool on the drawing are used to change the shape and shape of the workpiece.

Ordinary machine tools are more and more difficult to meet the needs of processing precision parts,

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.

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.

High speed and high precision

In order to improve the machining speed and precision of computer gong, we must pay attention to the influence of cutter tooth vibration on the surface roughness and tool life. In order to prevent the decline of machining accuracy and tool life, the selected machining center must be equipped with spindle with excellent dynamic balance performance, and the selected boring tool must also have high dynamic balance characteristics. Especially for the cutter teeth of boring tools, the geometry, tool material and clamping method suitable for high speed cutting should be selected. The R at the end of cutting edge should be larger in order to improve the processing efficiency; on the premise of ensuring the same surface roughness, the feed rate should be increased. But increasing the feed rate should be enough, otherwise it will increase the cutting resistance, which is not conducive to improving the processing efficiency. The cutting edge belt should be set with negative chamfering less than 0.1 mm, which can effectively maintain the stability of tool life. In addition to CNC cutting, boring and reaming can also be used for high precision machining. With the high speed of machining center spindle, boring tools can be used for high-speed precision machining of holes. It is reported that the cutting speed can be increased to more than 1500m / min when boring about 40mm on aluminum alloy. When CBN sintered body is used as cutting edge to process steel, cast iron and high hardness steel, such cutting speed can also be used.

As for the tool material, it depends on the nature of the material to be processed. For example, when machining steel below 40HRC, cermet tools can be selected. This kind of tool can obtain good surface roughness and long tool life under the condition of V = 300m / min or above. Coated cemented carbide tools are suitable for high speed cutting of steel below 60HRC. The tool life is very stable, but the cutting speed is slightly lower than cermet tools.

Sintered body tool is suitable for machining high hardness steel, cast iron and other materials, cutting speed can reach more than 1000m / min, and tool life is very stable. The edge belt of CBN cutter teeth should be chamfered properly, which is very beneficial to high speed cutting and tool life extension. In the ultra-high speed cutting of aluminum alloy and other non-ferrous and non-metallic materials, diamond sintered body tool can be selected. This kind of tool has the advantages of stable cutting and long tool life. It should be noted that when diamond tools are used, the cutting edge must be chamfered, which is an important condition to ensure the cutting stability.

Feed path of finishing

The feed route of finishing machining is basically carried out along the contour of the parts. Therefore, the key point of determining the feed route is to determine the feed route of rough machining and empty stroke. In the CNC lathe processing, the determination of the processing route should generally follow the following principles.

① It should be able to ensure the accuracy and surface roughness of the workpiece to be processed.

② The processing route is shortest, the idle travel time is reduced, and the processing efficiency is improved.

③ The workload of numerical calculation should be simplified as much as possible.

④ For some repeated programs, subroutines should be used.

Advantages and disadvantages of CNC CNC CNC machining has the following advantages:

① The number of tooling is greatly reduced, and complex tooling is not needed to process complex parts. If we want to change the shape and size of the parts, we only need to modify the processing program of the parts, which is suitable for the development and modification of new products.

② The machining quality is stable, the machining accuracy is high, and the repetition accuracy is high, which can meet the machining requirements of aircraft.

③ In the case of multi variety and small batch production, the production efficiency is high, which can reduce the time of production preparation, machine adjustment and process inspection, and reduce the cutting time due to the use of the best cutting quantity.

④ It can process complex surface which is difficult to be processed by conventional methods, and even process some parts which cannot be observed.

The disadvantage of NC machining is the high cost of machine tools and equipment, which requires high level of maintenance personnel.