CNC Technology – Page 69 – CNC Machining & Turning, Milling, Metal parts

High gloss and high precision machining method

Machining surface roughness is one of the important marks to measure the quality of machined surface. It has a great influence on the wear resistance, corrosion resistance, fatigue strength and matching properties of parts. However, there are many factors affecting the surface roughness in machining. In order to achieve good surface roughness, we will learn what these factors are.

1、 The reason of rough machining surface

1. Residual area: residual area refers to the area that remains on the machined surface after cutting by the main and auxiliary cutting edges of the tool.

2. Scale: when high-speed steel cutter is used to cut plastic metal materials at low or medium speed, such as low-carbon steel, medium carbon steel, stainless steel, aluminum alloy, etc., fish scale like burr is often produced on the machined surface, which is called scale bone. The appearance of scale will increase the surface roughness of the machined surface significantly.

3. Scab: in the process of cutting, when a chip is formed, the protruding part can replace the cutting edge to cut into the workpiece by computer gong machining | Dongguan computer gong machining | Shenzhen computer gong machining | mechanical parts processing | Guangzhou computer gong processing. The grooves of different depths are drawn on the machined surface; when the chip accretion falls off, part of the accumulated debris adheres to the machined surface and forms Small burr will increase the surface roughness.

4. Vibration: in cutting process, due to the periodic vibration of the process system, the machined surface appears streaks or ripple marks, and the surface roughness value increases significantly.

Machining: all factors that affect the residual area, scale, scale and vibration affect the surface roughness.

1. Cutting parameters: feed rate has the greatest influence on the residual area. When the feed rate decreases, the residual area decreases.

When cutting plastic metal, when cutting speed is very low or high, the surface roughness value is small. The reason is that it is not easy to produce chip lump at low speed, and the plastic deformation decreases when cutting speed is high, which can eliminate the formation of scale. When cutting brittle materials, the influence of cutting speed is small, because the deformation of material is small, the surface roughness value also decreases.

2. Geometric parameters of tool: the radius of tool tip arc, main deflection angle and secondary deflection angle have great influence on residual area and vibration. Generally, when the radius of the tool tip arc increases and the main and secondary deflection angles decrease, the surface roughness value is small. However, if the machine tool stiffness is low, the tool tip arc radius is too large or the main deflection angle is too small, the vibration will occur due to the increase of cutting force, which will increase the surface roughness value.

3. Tool material: the size of the edge arc radius and the time to keep sharp are different with different tool materials. High speed steel cutting tools can be grinded very sharp, but the holding time is short, so the surface roughness value is small when cutting at low speed. After grinding, the radius of the edge arc is larger, and the surface roughness is smaller at high speed.

4. Workpiece material: when processing plastic materials, the lower the plasticity and the higher the hardness of the workpiece material, there will be scaling, scaling and hardening, and the surface roughness will be smaller. The surface roughness ratio of carbon steel is low after machining.

What is CNC unit center

The operation and monitoring of CNC machine tools are all completed in this CNC unit, which is the brain of CNC machine tools.

Compared with ordinary machine tools, CNC machine tools have the following characteristics: computer gong processing, Dongguan computer gong processing, high-speed computer gong processing, mechanical parts processing, computer gong processing

High machining precision and stable machining quality;

It can carry out multi coordinate linkage and process parts with complex shapes;

When the processing parts are changed, the CNC program only needs to be changed to save the production preparation time;

The machine tool itself has high precision and rigidity. It can choose favorable processing amount and high productivity (generally 3 ~ 5 times of ordinary machine tool);

High degree of automation of machine tools can reduce labor intensity;

The requirements for the quality of operators are higher, and the technical requirements for maintenance personnel are higher.

CNC machine tools are generally composed of the following parts:

The main engine is the theme of CNC machine tools, including machine body, column, spindle, feed mechanism and other mechanical components. It is a mechanical part used to complete various cutting processes.

CNC device is the core of CNC machine tool, including hardware (printed circuit board, CRT display, key box, paper tape reader, etc.) and corresponding software for inputting digital part program, Dongguan computer gong processing, high-speed computer gong processing, mechanical parts processing, computer gong processing, etc The transformation, interpolation and Realization of various control functions.

Drive device, which is the driving component of the executive mechanism of CNC machine tool, including spindle drive unit, feed unit, spindle motor and feed motor, etc. Under the control of the numerical control device, he realizes the spindle and feed drive through the electric or electro-hydraulic servo system. When several feed linkage, positioning, straight line, plane curve and space curve processing can be completed.

Auxiliary device, some necessary matching parts of index control machine tool, to ensure the operation of CNC machine tool, such as cooling, chip removal, lubrication, lighting, monitoring, etc. It includes hydraulic and pneumatic devices, chip removal device, exchange table, CNC turntable and CNC dividing head, as well as cutting tools and monitoring and detecting devices.

Programming and other auxiliary equipment can be used to program and store parts outside the machine.

Since the first CNC machine tool was developed by Massachusetts Institute of technology in 1952, CNC machine tools have been widely used in manufacturing industry, such as computer gong processing, Dongguan computer gong processing, high-speed computer gong processing, mechanical parts processing, computer gong processing, especially in automobile, aerospace and military industries. Numerical control technology has been rapidly applied in both hardware and software development.

Curved surface molding mold processing

When machining the surface of aircraft and automobile parts, impeller, computer gong, propeller and various curved surface forming molds, the CNC machining center can ensure the accuracy requirements of special-shaped parts and curved surfaces, and greatly improve the processing efficiency. Next, let’s take a look at how the CNC machining center processes the special-shaped parts and curved surfaces?

The key work of NC machining center to process the surface of these dissimilar parts is to work out a reasonable machining program and select a suitable cutting tool. The work of the latter is relatively simple and can be completed quickly according to the mold drawing and process requirements. The preparation of Engineering sequence is the most important part of the whole preparation work, and it is also the whole mold processing The most important and important job.

Through the application of UG software in recent years, Shandong Weiwei Heavy Industry Machine Tool Co., Ltd., a manufacturer of CNC machining center, has summed up a set of NC programming methods suitable for all kinds of complex surfaces according to the common technical difficulties in the manufacturing process. The process of computer gong machining includes: establishing mathematical model, determining machining coordinate system, planning cutter location source file, etc.

1、 Establish mathematical model

Before establishing the model, we should first consider the order and method of establishing the features of the model. What should be done first, what should be done later, what method should be used, and what kind of modeling function should be used. This relationship must be properly dealt with when building a mathematical model.

2、 Determine the machining coordinate system

The establishment of solid model is based on working coordinate system, while the generation of machining tool location source file of CNC machining center is based on machining coordinate system. The position of the coordinate origin of the machining coordinate system should be convenient for the processor to quickly and accurately set the tool and to facilitate the size calculation needed in the processing process.

3、 Planning tool location source file

According to the structural characteristics of different product profiles, we can select three processing modules with their own characteristics, such as plane milling, computer gong machining cavity milling and fixed axis contour milling, to plan the machining tool location source files of various types of surfaces.

In a word, we should grasp the application characteristics of each module flexibly according to the different mold surface and contour surface, so that we can process the satisfied products with high quality and efficiency through the CNC machining center.

NC Machining Technology

CNC machining mainly refers to the use of digital information recorded on the media to control the machine tool. Dongguan computer gong processing makes it automatically perform the specified processing tasks. NC machining can ensure the products to achieve high machining accuracy and stable processing quality; the operation process is easy to realize automation; the productivity is high and the production cycle is short; it can greatly reduce the process equipment to meet the needs of rapid product update; it is usually closely linked with CAD to realize the transformation of design ideas to final products.

In the whole CNC processing process, we should focus on the relationship between the processes and the significance of each step. In a broad sense, the whole process consists of product analysis, graphic design, process planning, path generation, path simulation, path output, processing and inspection.

1. Some specific product information should be obtained through product analysis.

2. Graphic design the design of graphics should be based on the detailed analysis of the products. Dongguan computer gong processing determines the type of graphics by analyzing the processing requirements, and draws them by graphics software.

3. In fact, the process of path generation is to realize the process planning through software, and optimize the tool path by setting parameters.

4. Process planning is based on the analysis of the appearance and processing requirements of the workpiece products in the early stage, so as to reasonably establish each processing step from the overall processing situation.

5. After the path simulation path is generated, we generally have no intuitive feeling about the performance effect of its final processing on the machine tool. Here we can check the possible problems through path simulation, thus reducing the actual processing scrap rate. The key point of undercut is to check whether the process is reasonable or not.

6. Path output path output is a necessary step for software design and programming to realize on the machine tool. Through the path output, the relationship between the two can be established by the intermediate reference. If you have a professional background in CNC, it can also be understood as the post-processing of tool path.

Characteristics of CNC machining machine parts

Advantages: 1. High reliability

The reliability of large-scale mechanical parts processing equipment is guaranteed by using highly integrated electronic components, chips and VLSI.

Many functions are realized by software, which reduces the number of hardware.

Rich fault diagnosis and protection functions of mechanical parts processing (mostly realized by software), which can reduce the frequency of system failure and repair time after failure.

2. Easy to use and maintain

Easy to operate and use: Dongguan computer gong processing users only need to follow the menu prompts, you can operate correctly.

Programming and simulation functions are convenient and automatic.

Convenient maintenance and repair: some daily maintenance work is carried out automatically (lubrication, regular inspection of key components, etc.), the self diagnosis function of CNC machine tool for machining mechanical parts can quickly realize accurate fault location.

3. Easy to realize mechatronics

The small volume of CNC system control cabinet (using computer, the number of hardware is reduced; the integration of electronic components is higher and higher, and the hardware is constantly decreasing), which makes it possible to combine it with machine tool in physics, reduce the floor area and facilitate operation.

4. Flexibility and versatility

The functions of Dongguan machine parts processing device are mostly realized by software, and the software and hardware adopt modular structure, which makes the modification and expansion of system functions more flexible.

The basic configuration of Dongguan machine parts processing device is universal. Different CNC machine tools only configure corresponding specific function modules to achieve specific control functions.

5. Rich CNC functions

Interpolation function: quadratic curve, spline, spatial surface interpolation

Compensation function: motion precision compensation, random error compensation, nonlinear error compensation, etc

Man machine dialogue function: dynamic and static tracking display of processing, advanced man-machine dialogue window

Programming function: G code, basket chart programming, partial automatic programming function.

CNC machining and programming

Advantages: 1. High reliability

The reliability of large-scale mechanical parts processing equipment is guaranteed by using highly integrated electronic components, chips and VLSI.

Many functions are realized by software, which reduces the number of hardware.

Rich fault diagnosis and protection functions (mostly realized by software) can reduce the frequency of system failure and the repair time after failure.

2. Easy to use and maintain

Easy to operate and use: Dongguan computer gong processing users only need to follow the menu prompts, you can operate correctly.

Programming and simulation functions are convenient and automatic.

Convenient maintenance and repair: some routine maintenance work is carried out automatically (lubrication, regular inspection of key components, etc.), and the self diagnosis function of CNC machine tool can quickly realize accurate fault location.

3. Easy to realize mechatronics

Numerical control system control cabinet small size mold processing (using computer, the number of hardware is reduced; the integration of electronic components is higher and higher, and the hardware is constantly reducing), which makes it possible to combine it with machine tool in physics, reduce the floor area and facilitate operation.

4. Flexibility and versatility

Most of the functions of Dongguan Mechanical parts processing device are realized by software. The modular structure of software and hardware makes the modification and expansion of system functions more flexible.

5. Rich CNC functions

Interpolation function: quadratic curve, spline, spatial surface interpolation

Compensation function: motion precision compensation, random error compensation, nonlinear error compensation, etc

Man machine dialogue function: dynamic and static tracking display of processing, advanced man-machine dialogue window

Programming function: G code, basket chart programming, partial automatic programming function.

CNC machining process of precision parts

Machining process card: the process documents are required to be as detailed and complete as possible. In addition to the process catalog, there are also process cards for each process. Mechanical processing refers to the process of changing the overall dimension or performance of the workpiece through a kind of mechanical equipment. Dongguan mold processing has a variety of meanings: broadly speaking, it refers to the process of manufacturing products by mechanical means; in a narrow sense, it refers to the process of manufacturing parts with special machinery such as the lathe, milling machine, drilling machine, grinding machine, stamping machine, die-casting machine, etc.

There will be some errors in machining. Let’s talk about the original error related to the initial state of the process system itself

① Principle error is the error of machining method.

② Geometric error of process system

The relative position errors between workpiece and tool exist in static state, such as manufacturing error of tool and fixture, adjustment error and installation error;

The relative position error of workpiece and cutter exists in the motion state, such as the spindle rotation error of machine tool, the guide error of guide rail, the transmission error of transmission chain, etc.

(2) Original error related to cutting process

① The deformation caused by the force effect of the process system, such as the deformation caused by the stress deformation of the process system and the deformation caused by the generation and disappearance of the internal stress of the workpiece.

② Deformation caused by thermal effect of process system, such as the error caused by thermal deformation of machine tool, cutting tool and workpiece. In the machining process of Dongguan machine parts, when the position relationship between the tool and the workpiece processing surface is reasonable, the machining surface accuracy can meet the processing requirements, otherwise it can not meet the processing requirements. CNC machining accuracy analysis is to analyze and study various factors when the machining accuracy can not meet the requirements, that is, the possibility of various original errors, and take effective measures In order to improve the machining accuracy.

Characteristics of milling machine processing

It is characterized by:

1. The vertical milling head is equipped with tx400 heavy gantry milling head and double rectangular guide rail with strong rigidity;

2. The milling head is equipped with ball screw, pneumatic broach device and driven by servo motor;

3. The side milling head is equipped with V5 type gantry milling head, Dongguan high-speed computer gong processing is equipped with independent lubrication device, and the lifting is driven by ordinary reducer and frequency conversion speed regulation;

4. The three-axis CNC system with one key conversion from general milling to CNC milling can be programmed and operated manually by using the extended panel, which is highly realizable in the actual machining process;

5. The machine bed forward and backward, beam up and down, vertical milling head up and down are equipped with Taiwan ball screw, driven by servo motor;

6. Equipped with synchronous belt and synchronous wheel;

7. Hand held electronic hand wheel unit, convenient for three axis tool setting;

8. Dongguan machine parts processing unique beam lifting safety interlock device, CNC processing to ensure the repeated positioning accuracy of the machine tool;

9. The cycloid pump set is lubricated continuously with low failure rate.

Principle of CNC machining

According to the principle of “first rough then fine”, for parts with high precision requirements, the machining accuracy is gradually improved by the sequence from coarse to fine. Dongguan high-speed computer gong processing this point for poor rigidity parts, especially can not be ignored. In order to solve such problems, the characteristics of titanium alloy materials, machining characteristics, tool data selection, milling processing characteristics, coolant and other aspects are analyzed to improve the one-time acceptance rate of titanium alloy parts, so as to control the product quality of the parts. In order to better control the product quality, computer gongs processing, Dongguan computer gongs processing, high-speed computer gongs processing, mechanical parts processing, computer gongs processing must first control the cutting parameters of non-standard equipment parts processing, and grasp the processing characteristics of materials.

Mechanical processing technology is to change the shape, size, relative position and nature of the production object on the basis of the process. CNC processing makes it a finished product or semi-finished product. It is a detailed description of each process. For example, as mentioned above, rough machining may include blank manufacturing, grinding, etc., and finishing may be divided into turning, fitter, milling machine, etc., and each step is just like this There must be detailed data, such as how much roughness and tolerance should be achieved.

The classification of machining is as follows:

Design datum: the datum used to determine the position of other points, lines and planes on the part drawing, which is called design datum.

Process datum: the datum used in the process of machining and assembling parts, which is called process datum. According to different uses, the process datum of Dongguan mould can be divided into assembly datum, measuring datum and locating datum.

(1) Assembly datum: the datum used to determine the position of parts in parts or products during assembly, which is called assembly datum.

(2) Measurement datum: the datum used to check the size and position of machined surface, which is called measuring datum.

(3) Positioning datum: the datum used for workpiece positioning during machining, which is called positioning datum. For the surface (or line, point) as the positioning reference, only the rough surface can be selected in the first process, such as computer gong processing, Dongguan computer gong processing, high-speed computer gong processing, mechanical parts processing, computer gong processing. This positioning surface is called rough datum. In the future, the machined surface can be used as the positioning reference, and this positioning surface is called precision reference.

Fundamentals of CNC machining

The width of the worktable is less than 400mm for small and medium-sized CNC milling machines, which are suitable for the machining of small and medium-sized parts and the contour milling of complex surfaces. Large specifications such as the Dragon Gate milling machine, the worktable in 500-600mm above, used to solve the processing needs of large-scale complex parts.

Design datum: the datum used to determine the position of other points, lines and planes on the part drawing, which is called design datum.

Process datum: the datum used in the process of machining and assembling parts, which is called process datum. According to different uses, process datum can be divided into assembly datum, measuring datum and locating datum.

(1) Assembly datum: the datum used to determine the position of parts in parts or products during assembly, which is called assembly datum.

(2) Measurement datum: the datum used to check the size and position of machined surface, which is called measuring datum.

(3) Positioning datum: the datum used for workpiece positioning during machining, which is called positioning datum. Computer gong processing, Dongguan high speed computer gong processing, Dongguan mold processing, Dongguan Mechanical parts processing, CNC machining as the positioning reference surface (or line, point), in the first process, only the rough surface can be selected. This positioning surface is called the rough datum. In the following processes, the machined surface can be used as the positioning reference, and the positioning surface is called the precise reference.

In the process of turning a blank into a finished product, the total thickness of the metal layer cut off on a machining surface is called the total machining allowance of the surface. The thickness of the metal layer cut by each process is called the machining allowance between processes. For the rotating surface such as outer circle and hole, the machining allowance is considered from the diameter, so it is called symmetrical allowance (i.e. bilateral allowance), that is, the actual thickness of the metal layer cut off is half of the machining allowance on the diameter. The machining allowance of the plane is the unilateral allowance, which is equal to the actual thickness of the metal layer removed. The purpose of leaving machining allowance on the workpiece is to remove the machining errors and surface defects left by the previous process, such as the surface cold and hard layer, air hole and sand inclusion layer on the casting surface, oxide scale, decarburization layer and surface crack on the forging surface, internal stress layer and surface roughness after cutting. The precision and surface roughness of the workpiece are improved. The size of machining allowance has great influence on machining quality and production efficiency. If the machining allowance is too large, it not only increases the labor of machining, reduces the productivity, but also increases the consumption of materials, tools and power, and increases the processing cost. If the machining allowance is too small, it can not eliminate all kinds of defects and errors in the previous process, and can not compensate for the clamping error in this process, resulting in waste products. The selection principle is to make the allowance as small as possible on the premise of ensuring the quality. Generally speaking, the more finish machining, the smaller the process allowance.

Applicability:

In the process of turning a blank into a finished product, the total thickness of the metal layer cut off on a machining surface is called the total machining allowance of the surface. The thickness of the metal layer cut by each process is called the machining allowance between processes. For the rotating surface such as outer circle and hole, the machining allowance is considered from the diameter, so it is called symmetrical allowance (i.e. bilateral allowance), that is, the actual thickness of the metal layer cut off is half of the machining allowance on the diameter. The machining allowance of the plane is the unilateral allowance, which is equal to the actual thickness of the metal layer removed. The purpose of leaving machining allowance on the workpiece is to remove the machining errors and surface defects left by the previous process, such as the surface cold and hard layer, air hole and sand inclusion layer on the casting surface, oxide scale, decarburization layer and surface crack on the forging surface, internal stress layer and surface roughness after cutting. Computer gong processing, Dongguan high speed computer gong processing, Dongguan mold processing, Dongguan Mechanical parts processing, CNC processing, so as to improve the accuracy and surface roughness of the workpiece. The size of machining allowance has great influence on machining quality and production efficiency. If the machining allowance is too large, it not only increases the labor of machining, reduces the productivity, but also increases the consumption of materials, tools and power, and increases the processing cost. If the machining allowance is too small, it can not eliminate all kinds of defects and errors in the previous process, and can not compensate for the clamping error in this process, resulting in waste products. The selection principle is to make the allowance as small as possible on the premise of ensuring the quality. Generally speaking, the more finish machining, the smaller the process allowance. In order to formulate the machining process, it is necessary to determine the number of working procedures and the sequence of working procedures for the workpiece, and only list the name of the main process and its processing sequence, which is called the process route.