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How to prevent parts deformation in computer gong processing

As we all know, computer gongs processing is an automatic numerical control machinery, now many processing enterprises need this kind of mechanical equipment, but due to the fierce market competition, computer gongs processing chaos. The author suggests that before purchasing computer gong equipment, we must have a detailed understanding and investigation of the manufacturer.

Computer gong processing in the process of use will encounter some common faults, such as computer gongs can not return to zero, computer gongs positive and negative hard limit alarm, so what are the causes of these failures?

1、 Cause analysis of computer gong can not return to zero

1. The contact of the origin switch is stuck and cannot act; 2. The origin stop cannot hold the origin switch to the action position of the switch; 3. The water in the origin switch causes the contact of the switch to rust; 4. The line of the origin switch is disconnected or the input signal source is faulty; 5. The PLC input point is burnt out.

2、 Cause analysis of positive and negative hard limit alarm of computer gong

Computer gong processing under normal circumstances will not appear this alarm, but what is the cause of this situation?

1. The contact of the travel switch is pressed and stuck (over travel); 2. The travel switch is damaged; 3. The circuit of the travel switch is open circuit, short circuit and no signal source; 4. The limit block cannot hold the switch contact to the action position; 5. The PLC input point is burnt out.

Most of the time, due to the improper use of technical personnel, or work handover is not in place, computer gong processing will cause some problems, how should we prevent the deformation of parts in the process of computer gong processing?

Computer gong processing

In order to meet the requirements of ultra-high speed machining, the combination of spindle motor and machine tool spindle is adopted in computer gong machining, which realizes the integration of variable frequency motor and machine tool spindle. The bearing of spindle motor is in the form of magnetic levitation bearing, liquid dynamic and static pressure bearing or ceramic rolling bearing. Deformation often occurs in the process of processing, how to prevent it?

1、 In order to reduce the influence of cutting force and cutting heat, the deformation caused by rough machining can be corrected in finish machining.

2、 To reduce the influence of clamping force, the following measures should be taken to reduce the influence of clamping force:

1. When using radial clamping, the clamping force should not be concentrated on a certain radial section of the workpiece, and the operator should make it distributed over a large area to reduce the clamping force on the unit area of the workpiece.

2. The position of clamping force should be selected at the part with strong rigidity to improve the deformation of thin-walled parts under the action of clamping force.

3. The direction of clamping force is changed from radial clamping to axial clamping.

4. As we all know, computer gong is a kind of automatic numerical control machinery. Now many processing enterprises need this kind of mechanical equipment, but due to the fierce market competition, computer gong processing is chaotic. The author suggests that before purchasing computer gong equipment, we must have a detailed understanding and investigation of the manufacturer. In order to reduce the clamping deformation, special claws are used to clamp the workpiece, and the convex edge is cut off at the end of processing.

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How to adjust workpiece coordinate system in CNC machining

CNC machining process needs to be adjusted in many aspects. Due to the difference of machining parts, some adjustments need to be made before operation. Let’s take a look at how CNC machining adjusts the workpiece coordinate system?

CNC machining of aluminum parts

When adjusting the workpiece coordinate system, the reference point should be set outside the physical (geometric) length of all tools, at least on the tool location of the longest tool.

For the workpiece coordinate system on the workpiece installation drawing, the operator obtains it by setting the machine coordinate system offset on the machine tool. In other words, the operator sets a reference point on the machine tool, finds the dimension between the reference point and the zero point of the workpiece coordinate system set by the programmer, and sets this dimension as the offset of the workpiece coordinate system.

On the lathe, the reference point can be set at the tool carrier rotation center, the reference tool tip or other positions. If there is no additional movement, the zero of the programmer’s instruction is that the reference point of the tool rest (machine tool) moves to the zero position of the offset. At this time, if the reference point is set at the rotating center of the turret, the turret must collide with the workpiece. In order to ensure that there is no collision, the reference point on the machine tool should not only be set outside the tool holder, but also outside all the cutting tools. In this way, even if the tool holder is equipped with a tool, the reference point will not collide with the workpiece.

On the milling machine, the datum points of X and Y axes are on the axis line of the main shaft. However, the reference point of the Z axis can be set at the spindle end or at a point outside the spindle end. If at the spindle end, when the command is zero, the spindle end will reach the zero position specified in the coordinate system. At this time, the end key of the spindle end will collide with the workpiece: if the spindle is equipped with a tool, it will collide with the workpiece. In order to ensure no collision, the reference point on Z axis should be set outside all tool lengths. Even if no other motion is added, the reference point will not hit the workpiece.

CNC machining adjusting workpiece coordinate system is only a part, so what about CNC machining process?

(1) The technical preparation process includes market investigation, prediction, new product identification, process design, standardization review, etc.

(2) The technological process refers to the process of directly changing the size, shape, mutual position of surface, surface roughness or performance of semi-finished raw materials into finished products. For example, liquid forming, plastic forming, welding, powder forming, cutting, heat treatment, surface treatment, assembly and so on are all process processes. The reasonable process is written into a technical document to guide production, which is called process specification.

(3) Auxiliary production process refers to the auxiliary production activities necessary to ensure the normal operation of the basic production process.

(4) Production service process refers to the organization, transportation, storage, supply, packaging and sales of raw materials.

Difficulties in processing computer gongs

There are three common processing methods of computer gongs: vertical, horizontal and multi axis linkage. What is the difference between them? Let’s talk about it briefly.

1、 Vertical

Familiar with computer gongs processing friends all know that, due to the processing center spindle and worktable relative position is different, so the computer gong processing method is also different, so for operators, what are the common processing methods? 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.

2、 Horizontal computer gong 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.

3、 Multi axis linkage type computer gong machining center: it refers to the machining center which can control the linkage change of the spindle axis and the rotary axis of the worktable to complete the machining of complex space curved surface. It is suitable for the processing of impeller rotor, mold, cutting tools and other workpieces with complex spatial surface.

Familiar with the three ways of computer gong processing, but there will be some problems and difficulties in the process of computer gong processing. The author learned from a master who has been engaged in computer gong processing for many years. I hope the following contents can help you.

1. In the process of processing products, when the size of height direction changes greatly, do not adjust the depth of wear tool compensation. First, check whether there is aluminum slag in the tool handle and spindle, and then add wear cutter compensation after confirming that there is no slag.

2. A knife flicks around the corner. When it is found that there is a spring knife at the corner of the product, the size of the corner of the product is analyzed first, and the tool smaller than the R angle of the corner is used. It can also be solved by reducing the spindle speed.

3. When CNC machining deep holes with accuracy requirements, taper is easy to appear, especially when the hole depth is longer, it is difficult to ensure the upper and lower to the next. It can be rough first and leave a small amount of allowance before boring.

4. When using the jaw to clamp the products, the thickness is different, the outer dimension is thinner and the inner dimension is thicker. This is the external jaw clamping to jack up the product. Pay attention to whether the movable part of the jaw is too loose. After locking it, the problem of different product thickness can be solved.

5. The chamfering has burr. When there are burrs after chamfering, first check whether the tool is worn. If the tool is intact, then check the depth and range of chamfering. Generally, these two aspects can solve the problem of chamfering burr

How to determine the tool setting point of CNC machining center

Tool setting means that after the workpiece is aligned and tightened on the CNC machining center, the machine coordinate of the origin of the workpiece coordinate (programming coordinate) is determined (the value of X, y, Z of g54 is determined). Because a complete machining process of a workpiece may involve several or even dozens of cutting tools, because the trial cutting method is relatively primitive and the accuracy of tool setting is poor, it is rarely used. So how to determine the tool point of CNC machining center? After the center is aligned and tightened, determine the machine coordinate of the origin of the workpiece coordinate (programming coordinate) (determine the value of X, y, Z of g54). Because a complete machining process of a workpiece may involve several or even dozens of cutting tools, because the trial cutting method is relatively primitive and the accuracy of tool setting is poor, it is rarely used. So how to determine the tool point of CNC machining center?

CNC machining of aluminum parts

Tool setting point is the reference point used to determine the position of workpiece coordinate system in the machine coordinate system after the workpiece is aligned and clamped on the machine tool. The tool setting point can be selected on the workpiece or clamping positioning element, but there must be an accurate, reasonable and simple position corresponding relationship between the tool setting point and the workpiece coordinate point, so as to facilitate the calculation of the position of the workpiece coordinate point on the machine tool (the machine coordinate of the workpiece coordinate point). The tool setting point should coincide with the workpiece coordinate point.

The common tool setting methods of CNC machining center mainly include automatic tool setting method, tool setting instrument tool setting method, etc. How to realize the two common methods?

1. Automatic tool setting

The automatic tool setting is realized by using the tool detection function configured by the CNC machining center. This device can automatically and accurately measure the length of each tool in each coordinate direction, and can automatically correct the tool error value. The whole detection and correction process can be realized on the basis of the normal operation of the machine tool. This tool setting method is completely realized by electronic control device, which eliminates the error of manual tool setting, so the accuracy and efficiency of tool setting are higher.

2. Tool setting method of tool setting instrument

Tool setting instrument is the main tool setting method for CNC machining center because of its high economy. There are two kinds of tool setting instruments: inside and outside. The tool setting of the external tool setting instrument needs to be calibrated outside the machine tool in advance, and then the tool can be used after being installed on the machine tool; the tool setting of the internal tool setting instrument is a method to directly install the tool on a fixed position of the machine tool for measurement.

How to check the performance of CNC machining spindle

CNC machining center is an automatic processing equipment developed from CNC milling machine. The powerful processing ability of CNC machining center can bring higher work efficiency for enterprises. What environmental requirements do processing enterprises need to consider when installing CNC machining centers?

1. Location requirements

It should be far away from the vibration source and direct sunlight. If there is a seismic source nearby, an earthquake proof trench should be set up.

2. Temperature and humidity

The optimal processing temperature of CNC machining center is below 30 ℃. If the ambient temperature and humidity are too high, the service life of the control system components may be reduced. If the ambient humidity is too high, it may lead to the short circuit and fault of the integrated circuit board.

3. Voltage and current control

There are many processing equipment in the workshop, which will cause excessive fluctuation of the power grid. We need to control the voltage and current within the allowable range of the machining center and keep it stable, otherwise the work of the system may be affected. The power supply shall be 380V ± 10%, three-phase AC.

As we all know, after the installation of CNC machining center, the acceptance still needs to be done, because the acceptance of CNC machining center directly affects the equipment put into use of the manufacturer. The general factory acceptance standard is to directly carry out the workpiece processing test. In fact, after the workpiece processing test, it can be basically determined that the key parts of the machining center meet the standards, and in the case of normal use There is no problem. About CNC machining center spindle performance inspection is what?

1. Select low, medium and high speed. The main shaft starts 5 times in a row, then stops the operation to check the flexibility and reliability of its action. At the same time, check whether the power display on the load meter meets the requirements.

2. It can input data manually, so that the spindle gradually increases from low speed to the maximum allowable speed. Check whether the speed is normal, the general allowable error should not exceed ± 10%. While checking the spindle speed. Observe whether the noise, vibration and temperature rise of the spindle are normal. The temperature rise of the spindle is 15 “C after running at high speed for 2 h.

3. In order to check the flexibility and reliability of the spindle action, the spindle can be stopped accurately and operated continuously for more than 5 times.

How to solve the problem of Tool Collision in CNC machining center

The selection of NC cutting tools and the determination of cutting parameters are important contents in CNC machining process. They not only affect the machining efficiency of CNC machine tools, but also directly affect the processing quality. So how do CNC machining enterprises choose cutting tools?

The tool selection and cutting parameter determination of CNC machining center is completed in the man-machine interaction state, which forms a sharp contrast with the ordinary machine tool processing. At the same time, it also requires the programmer to master the basic principles of tool selection and cutting parameter determination, and fully consider the characteristics of numerical control processing in programming, and be able to correctly select the cutting tools and cutting parameters.

The general principles of tool selection are: easy installation and adjustment, good rigidity, high durability and precision. On the premise of meeting the machining requirements, the shorter toolholder should be selected as far as possible to improve the rigidity of tool processing

Familiar with the importance of cutting tools for CNC machining, it is inevitable that tool collision will occur in the process of use. For example, problems in the origin and coordinate system of CNC machining center will lead to Tool Collision fault. How to solve this problem?

When starting the machine, the origin of the machine tool is not set. If the program is run at this time, it will cause the machine tool to collide with the cutter, because the system does not know the exact position of the machine tool, and the mechanical origin is incorrect. So we should check the CNC machining center coordinate system origin setting before starting.

For the setting of workpiece coordinate system, before machining operation, zero point setting or coordinate system setting of workpiece coordinate system are correct. At this time, CNC machining center will not have the problem of tool collision or incorrect size of workpiece

What is CNC thread milling method

If you want to be a master in the operation of CNC machining center, you must stand the experience of time and constantly improve your working ability. In the CNC machining industry, the programming of CNC machining center should be compiled according to the operation characteristics of machine tools, which is conducive to observation, inspection, measurement and safety. For example, the same parts, the same processing content, vertical processing, and horizontal processing, respectively processing, the program is certainly not the same.

CNC machining parts

Skilled in operating CNC machine tools. This requires 1-2 years of study, the operation is pay attention to the feel, beginners, especially college students, know how to do, but the hands just don’t listen. In this process, we should learn: system operation mode, fixture installation, part reference alignment, tool setting, zero offset setting, tool length compensation, radius compensation, loading and unloading of tool and handle, tool grinding, parts measurement (skilled use of vernier caliper, micrometer card, dial indicator, dial indicator, inner diameter lever gauge).

Can reflect the level of an operator is: 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.

In the process of CNC machining, there is a method called thread milling. What is the specific meaning? Thread milling with CNC is a 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 cutting tool 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, especially suitable for the screw thread processing of difficult to machine materials such as aluminum, copper, stainless steel, etc,

It is especially suitable for thread processing of large parts and components of valuable materials, which can ensure the quality of thread processing and the safety of 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.

Causes of abnormal noise of spindle in CNC machining center

The spindle is the power auxiliary device of CNC machining center. The spindle drives the workpiece to rotate, which is used to process the workpiece of revolving 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 failure are the basic knowledge that operators and maintenance personnel of CNC machining center must master. When operating CNC machining center, the spindle will inevitably have some faults. What are the specific reasons?

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 drive spindle with variable speed gear, the main transmission spindle through belt drive, the spindle driven by dual motors and the spindle integrated by motor and spindle. No matter what type of spindle application, the common faults in use are as follows:

1. Overload.

Fault causes: excessive cutting amount, frequent positive and negative rotation, spindle motor failure, spindle drive device failure.

2. The spindle does not rotate

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

3. Spindle speed deviates from the command value

Fault causes: motor overload, problems with spindle speed command output from CNC system, fault of speed measuring device or disconnection of speed feedback signal.

4. Abnormal noise and vibration of spindle

CNC machining parts

Fault cause: it usually occurs in the process of deceleration, and the spindle drive device has problems, such as the regeneration circuit fault in AC drive.

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

When the machining center is in use, customers often find that the main shaft is transmitted by belt. After a long time of use, there will be abnormal noise. When the forward transmission and reverse rotation are switched, there will be noise. According to years of assembly experience, most of the problems are belt, The belt tension at the connection between the servo motor and the spindle is too tight, which causes the belt to slip, and the spindle will make abnormal noise.

There is also a case that the tension of the belt connecting the servo motor is not enough, so the belt of the motor is too loose, which can be seen intuitively. When using the machining center to re chip, there will be slip and abnormal noise. The belt will be worn after the machining center is used for a long time, which is part of the cause of abnormal noise.

After CNC machining center spindle abnormal noise, some economical customers will choose to replace the transmission wallet. After the replacement, the belt drive gear does not match with the tooth type of the motor and the spindle, which can also make do with it. However, there will be a great abnormal noise during the use, which will seriously cause the wear and damage of the gear between the servo motor and the spindle. It is recommended to observe whether the model of the belt purchased and replaced is the same

How to deal with over cutting problem of CNC machining center

Milling cutter is used for machining plane, step, groove, forming surface and blocking workpiece on CNC machining center milling machine, which has a great influence on the quality of machined parts, so how to choose the appropriate milling cutter? What are the principles?

The milling cutter used in CNC machining center should be made of all cemented carbide, and the one used in general milling machine should be made of white steel. The hardness of white steel milling cutter and carbide milling cutter is relatively soft. Cemented carbide milling cutter has good thermal hardness, wear resistance, but poor impact resistance. If you drop the blade at will, it will be broken. Cemented carbide is made by powder metallurgy. Its hardness can reach about 90hra and its thermal property can reach 900-1000 degrees.

1. Number of teeth of milling cutter

When selecting a milling cutter, the number of teeth should be considered. For example, a thick tooth milling cutter with a diameter of 100 mm only needs 6 teeth, while a close tooth milling cutter with a diameter of 100 mm can have 8 teeth. The size of tooth pitch will determine the number of cutter teeth participating in cutting together during milling, and affect the stability of cutting and the requirement of cutting rate of machine tool.

2. Chip holding tank

Rough tooth milling cutter is often used for rough machining because it has a large chip groove. If the chip holding groove is not large enough, it will cause chip rolling difficulty or chip conflict with cutter body and workpiece. Under the same feed rate, the cutting load of coarse tooth milling cutter is larger than that of dense tooth milling cutter.

CNC machining of aluminum shell

3. Cutting depth

In finish milling, the cutting depth is shallow, generally 0.25-0.64mm. The cutting load of each tooth is small (about 0.05-0.15mm), and the required power is not large. It can select the dense tooth milling cutter and select a larger feed rate.

4. Application of rough milling

In heavy load rough milling, excessive cutting force can make the machine tool with poor rigidity vibrate. This kind of vibration will cause the carbide blade to break and then shorten the tool life. The use of coarse tooth milling cutter can reduce the requirement of machine power.

The price of milling cutter used in CNC machining center is relatively expensive. The price of a face milling cutter with a diameter of 100 mm may cost 3000 yuan, so it should be selected steadily. Many people who have operated CNC machining center have encountered over cutting problem. How to deal with this situation?

The workpiece processing process of CNC machining center is no longer like the traditional processing equipment. It needs to continuously control the machine tool to finish, and control the functional parts of the machine tool to carry out messy and precise actions, and then finish the processing process with high precision and high efficiency. The programming of workpiece processing is the key of machining center. However, if the programming is not reasonable or the parameters are not set properly, the machining accuracy and power of the workpiece will be seriously affected, such as over cutting. Overcutting is a serious problem in workpiece processing, which can lead to the invalidation of workpiece. For some reason, the front-line processing personnel have worked out the machining program which is sure to occur overcutting. The system can announce the alarm signal in advance in the working process, so as to avoid the occurrence of over cutting. How to judge the cause of over cutting in CNC machining center?

CNC machining of aluminum parts

1. Overcutting in arc machining of machining center

In machining center, if the tool radius RD is too large and exceeds the required arc radius r r, it is likely to cause over cutting. The NC machining program is compiled according to the practical summary track of workpiece, without considering the motion track of tool in the process of practical machining. Because of the existence of tool radius, the tool practice track becomes thick and does not coincide with the programming track. In order to get the correct summary of the workpiece surface, it is necessary to set the tool radius compensation command between the tool path and the programming track. Otherwise, over cutting of workpiece will be inevitable.

2. The discrimination of cutting straight line

In CNC machining center, if the tool radius is too large, it is very likely to cause overcutting and then void the workpiece. It can distinguish the positive and negative of the scalar product of the programming vector and its corresponding correction vector.