chengcg – Page 27 – CNC Machining & Turning, Milling, Metal parts

CNC machining center cutting oil

It often causes oil leakage in CNC machining center. There are three main problems in oil change. First, for the parts with high viscosity lubricating oil, it will affect the sealing performance of the corresponding box, shaft hole and other parts, and sometimes greatly reduce the sealing performance of these parts. Second, if the oil tank is not cleaned when changing oil, the dirt in the oil tank may enter into the lubrication system, block the oil circuit and wear the seals, causing oil leakage. Third, when changing the oil, the amount of oil is too much, especially in the parts with rotating parts, because of the stirring effect of rotating parts, it is more prone to oil spill.

Improper selection and adjustment of lubrication system parts cause oil leakage.

For example, when CNC machining and maintenance personnel select the oil pump with too high pressure or too large oil output, or when adjusting the system pressure, the pressure of relief valve, safety valve and pressure reducing valve is too high, and the flow of CNC machine tool lubrication system is too large, which does not match with the oil return system and sealing system, it will cause oil leakage.

In fact, it is not just the above points that cause the oil leakage of CNC machining center. If we encounter similar problems in operation, we must do a good job in checking and find out the reasons in time to avoid unnecessary losses. After the purchase of the machining center, do a comprehensive inspection to see if there are casting defects or parts damage, if any, contact the manufacturer in time. When operators use CNC machining center to process workpieces, they should also pay attention to the following points:

(1) For the first trial cutting process of CNC machining, the single-stage operation mode should be adopted.

(2) When the CNC milling machine starts to run automatically, the fast rate and feed rate s are in the lowest gear, and then the efficiency is improved after cutting into the workpiece.

(3) In the operation of NC milling machine, we need to pay attention to the coordinate display of CNC system.

CNC thread milling method

To be proficient in the operation of CNC machine tools, we should learn: system operation mode, fixture installation, part benchmark alignment, tool setting, zero offset setting, tool length compensation, radius compensation, tool and handle loading and unloading, tool grinding, part measurement (proficient in using vernier caliper, micrometer, dial indicator, dial indicator, inner diameter lever), etc .

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, but it is difficult to be quantitative.

In the process of CNC machining, there is a method called thread milling. What is it? CNC thread milling is a milling method which uses thread milling cutter, machining center three-axis linkage, namely x, Y axis arc interpolation, Z axis linear feed.

Thread milling is mainly used for large hole thread and difficult to machine material thread hole. It has the following characteristics:

(1) high processing speed, high efficiency and high processing precision. The cutting tool is made of cemented carbide, and the cutting speed is fast. Therefore, the precision of thread milling tool is high.

(2) milling tools are widely used. As long as the pitch is the same, whether it is * * thread or right-hand thread, a tool can be used, which is conducive to reducing the cost of the tool.

(3) milling is easy to remove chips and cool, and the cutting condition is better than tap. It is especially suitable for thread machining of difficult to machine materials such as aluminum, copper and stainless steel,

Especially suitable for large parts and valuable material parts of the thread processing, to ensure the quality of thread processing and workpiece safety.

(4) because there is no tool front-end guide, it is suitable for processing blind holes with short thread bottom holes and holes without undercut.

The highest precision of computer gong processing

Machining center in the process of processing mold, the accuracy and surface processing quality requirements are higher and higher, in order to ensure the quality of mold processing, we should consider the selection of machine tool, tool handle, tool, processing scheme, program generation, operator requirements and other aspects.

With the improvement of product design requirements and the development of high-speed and high-precision processing technology, the selection of high-precision and high-speed machining center has greatly improved the quality and speed of mold NC processing, reduced the processing procedures, shortened the production cycle and clamping times of mold, and sometimes eliminated the time-consuming fitter repair work. The high-speed and high-precision machining of mold has gradually become one of the important contents of the technological transformation of mold production enterprises. It is inevitable that the high-speed CNC machining center will replace the traditional low-speed machining, and the development of mold manufacturing technology will also bring us more rich product experience.
The use of high-speed and high-precision machining center with suitable tool handle structure will also drive the update of relevant process equipment. In particular, the influence of cutting tools on NC machining quality and toolholder will become prominent. In the rotary tool processing system, the chuck is closely connected with the machine tool (or its combination) to ensure the realization of tool processing performance. Generally, there are HSK hollow toolholder and BT toolholder in the interface between machine tool and toolholder. The taper of taper shank interface between machine tool spindle and BT toolholder is 24:7, which is suitable for traditional low-speed machining. Because BT toolholder and machine tool spindle are only taper fit, the clearance of taper fit will increase under the action of high-speed centrifugal force, which affects the quality of NC machining. Generally, when the spindle speed exceeds 16000 rpm, we will need to use HSK hollow handle. The positioning structure of HSK arbor is over positioning, which provides a standard connection with the machine tool. Under the pulling force of the machine tool, the short cone and end face of the arbor are closely matched with the machine tool.
Choosing the right cutting tools, the reasonable use and selection of cutting tools will be an important factor affecting the quality of NC machining. Cemented carbide tools are more and more widely used. In high speed machining, coated cemented carbide will replace most of the front steel tools, including reamer, ball head tool, boring tool and other simple tools. Coated cemented carbide will play an important role in high speed machining tool materials and be applied to most of the conventional processing fields. Generally, we know that in rough machining, we will use large diameter tools for processing. In order to save cost and reduce the difficulty of tool manufacturing, we will use machine clip cemented carbide blade In the semi finish machining, the insert tool with high speed and high feed is used to make the semi finish machining move faster; in the finish machining, the high-precision round head mirror blade is used to ensure the strength of the tool and the tool holder, which can save the expensive cost of selecting the whole alloy tool while maintaining the machining accuracy. In the process of machining, we also need to pay attention to the inner contour fillet radius of the finishing parts must be greater than or equal to the radius of the tool, select the tool whose radius is less than the radius of the corner fillet to process in the way of arc interpolation or diagonal interpolation, so as to avoid the phenomenon of overcutting caused by linear interpolation and ensure the quality of mold finishing.
The importance of NC process design in high-speed and high-precision machining is raised to a higher position. The whole process of machining must be controlled. Any error will have a serious impact on the mold quality, so the process design will play a decisive role in the machining quality. NC machining process design can be considered as the state control of a system process plan from the part blank to the part forming. A good process plan is difficult in the whole design process, which can be obtained only after continuous practice summary and modification. A large amount of information should be considered in the design process, and the relationship between the information is extremely complex, which must be guaranteed by the actual work experience of the programmer. Therefore, the design quality of process plan mainly depends on the experience and level of technical personnel.

Generally, a complete NC machining process planning includes the following contents:

1) CNC machine tool selection.

2) Processing method selection.

3) Determine the clamping mode of the part and select the fixture.

4) Positioning method.

5) Inspection requirements and methods.

6) Select the tool.

7) Error control and tolerance control in machining.

8) Define NC process.

9) Numerical control process sequencing.

10) Cutting parameter selection.

11) Work out NC process program sheet.

CAM software a good software can also improve the quality and efficiency of mold processing, such as Unigraphics and cimiamtron , are very good mold processing software, especially the two kinds of software rich practical different processing strategy, in NC milling programming, turning programming, WEDM programming are widely used, complement each other, so that the quality and efficiency of NC machining has been greatly improved. Cimiamtron can add the screw function when clearing the offset area in rough machining, which will make the actual cutting more stable, eliminate the mutation of feed direction between adjacent tool paths, reduce the acceleration and deceleration of cutting feed, maintain a more stable cutting load, prolong the tool life, and also play a good role in protecting the machine tool. Software is just a tool. An excellent programmer has rich experience and theoretical knowledge of on-site machining. At the same time, the NC programmer who is proficient in the software function is the decisive factor in the mold NC machining, which plays a key role in the quality and efficiency of NC machining.
The operator of machining center is the executor of NC machining, and their control of NC machining quality is also very obvious. In the process of performing processing tasks, they know the real-time status of machine tools, toolholders, cutting tools, processing technology, software and cutting parameters best, and their operations have the most direct impact on NC machining, so the skills and sense of responsibility of machining center operators are also the key factors to improve the quality of NC machining!

High precision parts manufacturing

The concept, significance and characteristics of high precision parts manufacturing high precision parts manufacturing takes high precision mechanical parts as processing objects. Based on the systematic and integrated theory and technology, according to the structure and requirements of the workpiece, the organic combination and optimization of feeding, processing, detection and handling are realized, and the production of parts is completed under the precise processing conditions.
Application field of high precision parts and components high precision parts and components are used in all walks of life testing equipment – scientific instruments. In China, they are mainly used in the instrument and instrument industry of scientific instruments.
High precision machining has the advantages of high precision, low energy consumption, flexible production and high efficiency. Reducing the size of the whole manufacturing system and precision parts can not only save energy, but also save manufacturing space and resources, which is in line with the production mode of energy saving and environmental protection. It is one of the development directions of green manufacturing.
Compared with ordinary machinery manufacturing, precision machinery manufacturing has high technology content (design and production), excellent processing equipment, high added value, and small batch sales.
Analysis of foreign development situation high precision machinery manufacturing technology is known as one of the key technologies in the 20th century. It is the key development direction in the 21st century and has been highly valued by all countries in the world. Japan, the European Union, South Korea, the United States and other developed countries have invested a lot of human, material and financial resources to develop their own high-precision mechanical parts research and development and technology.
China’s high-precision machinery manufacturing technology was gradually developed in the late 1980s and early 1990s. It is a rapidly developing industry in China today. High precision machinery manufacturing products are widely used in national defense, medical, aerospace, electronics and other military and civil fields.

CNC machining center fault inspection

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.

CNC machine tool debugging

Before the debugging of CNC computer gong processing machine tool, the debugging methods for the precision and function of CNC computer gong processing machine tool are as follows:

Using precision level instrument and other testing tools, the main bed level of the computer gong processing machine tool is precisely adjusted by adjusting the pad iron, so that the geometric accuracy of the machine tool can reach the allowable tolerance range;
For the automatic tool changing device, adjust the position of tool magazine, manipulator, stroke parameters, etc., and then check the action with instructions to ensure accuracy;
For the machine tool with APC automatic exchange table, after adjusting the relative position, carry out automatic exchange;
After the adjustment of the machine tool, carefully check whether the parameter setting values in the numerical control system and the programmable controller conform to the data specified in the random index, and then test the main operation functions, safety measures, and the execution of common instructions.
Check the auxiliary functions and accessories of the machine. CNC machining is the basis of modern manufacturing technology. This invention has epoch-making significance and far-reaching influence for the manufacturing industry. CNC machining centers are usually classified by the relative position of the spindle and the workbench, which are divided into vertical, horizontal and multi axis linkage machining centers.

1、 Vertical machining center: it refers to the machining center with the spindle axis perpendicular to the worktable. It is mainly suitable for processing plate, plate, mold and small shell complex parts.

2、 Horizontal machining center: it refers to the machining center with the spindle axis parallel to the workbench, which is mainly suitable for machining box parts.

3、 Multi axis linkage machining center: it refers to the machining center that can control the linkage change by processing the angle between the spindle axis and the rotary axis of the worktable, and complete the machining of complex spatial surface. It is suitable for the machining of impeller rotor, mold, cutting tool and other workpieces with complex spatial surface.

How to improve the efficiency of CNC machining

(1) The size and structure of all kinds of parts are very different, and the universality of machine tools and other process equipment is not high.

(2) Many companies are usually faced with the production task of multi variety, small batch and short production cycle, so the process system is required to have a higher response speed.

(3) The structure of product parts is complex and the processing is difficult.

(4) Thin wall, easy to produce processing deformation. There are a lot of thin-walled and deep cavity structures, which are typical weak rigid structures.

(5) It is difficult to select cutting tools and cutting parameters. Because the development of tool industry can’t catch up with the development and application of new materials, and lack of the support of machining database.

So how to improve the efficiency of CNC machining? Generally speaking, the methods to improve the machining efficiency of CNC machine tools are as follows:

1、 Change the understanding of numerical control technology.

Numerical control technology is a comprehensive technology, in addition to the numerical control machine tool, there must be corresponding supporting technology and personnel support, especially in the numerical control processing process, people play a decisive role, the technical ability of management personnel, engineering and technical personnel, engineering maintenance personnel and operators will affect the production efficiency of numerical control machine tool.

2、 Develop effective tool management measures.

For example, the tool is pre adjusted to reduce the installation and adjustment time of the tool on the machine tool, and the tool is managed through the management system to reduce the errors caused by manual management.

3、 Fixture management.

Because the selection of fixture is directly related to the installation time and measurement time of workpiece, the management of fixture should be realized.

Computer gong processing workpiece collision number

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.

Computer gong processing tool setting point

When the machining accuracy is not high, some surfaces on the workpiece or fixture can be directly used as the tool face; when the machining accuracy is high, the tool setting point should be selected on the design basis or process basis of the part as far as possible, for example, for the part with hole positioning, it is more appropriate to take the axis of the hole as the tool setting point. The tool setting point must have a certain coordinate relationship with the positioning datum of the workpiece. In this way, the relationship between the machine tool coordinate system and the workpiece coordinate system can be determined. The selection of tool setting point should be convenient for coordinate value calculation and tool setting. During tool setting, the tool setting point should coincide with the tool position. The so-called cutter site refers to the intersection of the tool axis and the bottom surface of the tool for the flat end end milling cutter; for ball end milling cutter, it refers to the ball center of the ball head part; for turning tool, it refers to the tool tip; for the drill bit, it refers to the drill point; for the linear electrode cutting machine, it refers to the focus of the axis of the wire electrode and the part surface.

Stress and warpage analysis based on two-sided flow technique

According to the analysis results of gate solidification effect and packing pressure and temperature distribution, the stress and warpage analysis module calculates the stress changes with time in the wall thickness and plane direction of the product, and the shrinkage of the product along the wall thickness direction at the time of demoulding. Based on the double-sided flow technique, a special double-layer shell element is used to predict the warpage of the product at the time of demoulding.

The standard of CNC programming program

It takes 1-2 months to be very familiar with. The automatic programming software is a bit complicated and needs to be learned. But it is not difficult for CAD.

In practice, one is:

Readable, well organized, and understood by everyone in the operator.
The program instructions should be as few as possible for the purpose of simple, practical and reliable. From the point of view of programming, I think that the instruction G00 G01 and other auxiliary instructions are convenient for programming.
Easy to adjust. Parts machining accuracy need to be fine tuned is the best without changing the plan. Tool wear, for example, adjustment, just change the tool offset table length, radius.
Easy to operate. Programming will be based on the characteristics of machine operation, conducive to observation, inspection, measurement, safety, and so on. The same parts, for example, the same processing content, in the vertical machining center and horizontal machining center processing, are certainly not the same.

In machining, the simplest method is the best. As long as there is practical experience of the peer, will certainly agree with this sentence!

Skillfully operate CNC machine tools

This requires 1 – 2 years of research, operation delicate feeling, beginners, especially college students, know how to do, can not listen. Learn in this process: operation mode of installation system, clamp, datum alignment, knife, setting zero point offset, setting tool radius, length compensation, compensation, handling of tool and loading and unloading, grinding tools, measurement, skilled use of vernier caliper, micrometer, dial indicator, dial indicator, rod diameter indicator, etc.