Category Archive CNC Technology

advantage:

First: when the parts of the computer gong processing are changed, the computer gong processing generally only needs to change the numerical control program, which can save the production preparation time.

Second: mass production, product quality is easy to control.

Third: the precision and rigidity of the computer gong machine tool itself is high. It can choose favorable processing amount and high productivity (generally 3 ~ 5 times of the ordinary machine tool).

Fourth: can carry out multi coordinate linkage, can process complex shape parts.

Fifthly, it has high machining precision and high processing quality.

Sixth: machine tool automation is high, computer gong processing can reduce labor intensity.

Disadvantages:

First: the computer gongs processing requires lower quality of operators and higher technical requirements for maintenance personnel.

Second: but its processing route is not easy to control, not as intuitive as ordinary machine tools.

Third: its maintenance inconvenience, computer gongs processing technology requirements are high.

报错 笔记

1. When processing parts, the protective door must be closed. It is not allowed to stretch the head and hand into the protective door. It is not allowed to open the protective door during processing;
2. During the processing of Dongguan computer gong, the operator shall not leave the machine without authorization, and shall keep a high degree of concentration and observe the running state of the machine tool. In case of any abnormal phenomenon or accident, the program operation shall be terminated immediately, the power supply shall be cut off and the instructor shall be informed in time. No other operation shall be carried out;
3. It is strictly forbidden to beat the control panel and touch the display screen. It is strictly forbidden to knock the worktable, dividing head, clamp and guide rail;
4. It is forbidden to open the control cabinet of CNC system to watch and touch without permission;
5. Dongguan computer gong processing operators are not allowed to change the internal parameters of the machine. Interns are not allowed to transfer or modify other programs that are not compiled by themselves;
6. On the control computer of machine tool, no other operation is allowed except program operation, transmission and program copy;
7. CNC milling machine belongs to large precision equipment. In addition to tooling and workpieces placed on the worktable, it is strictly forbidden to stack any tools, clamps, cutting edges, measuring tools, workpieces and other sundries on the CNC Gong processing machine tool in Dongguan;
8. It is forbidden to touch the blade tip and iron filings by hand. Iron scraps must be cleaned with iron hook or brush;
9. It is forbidden to touch the rotating spindle, workpiece or other moving parts by hand or any other means;
10. It is forbidden to measure the workpiece and change the speed manually in the process of processing. It is not allowed to wipe the workpiece with cotton thread or clean the machine tool;
11. No attempt operation is allowed;
12. When using the handwheel or fast moving mode to move the position of each axis, make sure to see the “, -” signs in all directions of X, y and Z axes of the machine tool before moving. When moving, slowly turn the hand wheel to observe the moving direction of the machine tool, and then speed up the moving speed.

CNC machining mainly refers to the use of digital information recorded on the media to control the machine tool, so that it can automatically carry out 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. Students in the whole CNC process learning 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. In this section, a specific case is demonstrated, focusing on understanding the connection of each link. The case processing material is double color plate or plexiglass

1. Product analysis through product analysis should obtain certain composition information and some specific processing requirements
2. Graphic design the graphic design should be based on the detailed analysis of the product. For example, for the processing of the seal, we should determine the font, text size, seal type by analyzing the processing requirements
3. Process planning through the analysis of the appearance and processing requirements of the workpiece products, from the overall situation of the processing to establish each processing step reasonably. 4. The process of path generation path generation is that we realize the process planning through software, and optimize the tool path through the setting of parameters
4. After the path simulation path is generated, we generally have no intuitive sense of its final performance on the machine tool. Here we can check the possible problems through path simulation, Dongguan computer gong processing, Dongguan Mechanical parts processing, Dongguan precision computer gong processing, Dongguan high-speed computer gong processing, so as to reduce the actual processing scrap rate. The general inspection focuses on the effect of workpiece appearance, whether it is overcut or undercut, and whether the process planning of the path is reasonable
5. 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 the students have the professional background of numerical control, they can also understand it as the post-processing of tool path.

What is precision machinery parts processing, as the name suggests, it is a kind of mechanical processing, but more precise processing, with the development of industry and the continuous change of demand, close machining has changed a lot, its classification is more and more, its direction as long as it is more and more detailed, the direction is more and more specialized, with the development of science and technology, its technology is also constantly improved The quality and accuracy of processing are also higher and higher. With the development of science and technology and economy, the direction of machinery development is closely related

Production types are generally divided into three categories:

1. Single piece production: products with different structures and sizes are produced individually, and rarely repeated.
2. Batch production: the same products are manufactured in batches in a year, and the manufacturing process has certain repeatability
3. Mass production: a large number of products are manufactured, and most workplaces often repeat a certain process of a certain part. (1) The designed process specification shall ensure the processing quality of machine parts (or the assembly quality of the machine) and meet the technical requirements specified in the design drawing.

(2) It is necessary to make the technological process have higher productivity and put the products on the market as soon as possible.

(3) Try to reduce manufacturing costs

(4) Pay attention to reduce the labor intensity of workers to ensure the safety of production.

(1) Product assembly drawing, part drawing.

(2) Product acceptance quality standards.

(3) Annual production program of products.

(5) The production conditions of the manufacturer include the specifications, performance and current status of machine tool equipment and process equipment, the technical level of workers, the ability of self-made process equipment, and the power supply and gas supply capacity of the factory.

(6) Design manual and relevant standards required for process planning and process equipment design.

(7) Advanced manufacturing technology data at home and abroad.

Large computer gong machining centers are usually classified into horizontal, vertical and multi axis linkage machining centers according to the relative position of the spindle and the worktable.

A horizontal 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.

B vertical machining 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.

C multi axis linkage machining center, also known as universal machining center, refers to the machining center which can control the linkage change through the angle between the spindle axis and the rotary axis of the worktable to complete the machining of complex spatial curved surface. It is suitable for machining impeller rotor, mould, cutting tool and other workpieces with complex space curved surface.

1. It belongs to cutting CNC machine tool

Corresponding to the traditional turning, milling, drilling, grinding and gear processing, CNC lathes, CNC milling machines, CNC drilling machines, CNC grinding machines, CNC gear processing machines, etc. Although there are great differences in the processing methods of these CNC machine tools, and the specific control methods are also different, the actions and movements of the machine tools are digital control, with high productivity and automation.

1. CNC machine tools for plate processing
2. CNC machine tools for special machining

In addition to cutting CNC machine tools, CNC technology is also widely used in CNC WEDM machine tools, CNC EDM forming machines, CNC plasma arc cutting machines, CNC flame cutting machines, CNC laser machining machines, mold accessories processing, etc.

The common CNC machine tools used in sheet metal processing include CNC press, CNC shear and CNC bending machine.

In recent years, CNC technology has been widely used in other mechanical equipment, such as CNC multi coordinate measuring machine, automatic drawing machine and industrial robot.

2、 Classification by control trajectory

1. Point control CNC machine tool

Accurate positioning of the position, no processing is carried out in the process of moving and positioning. The CNC system only controls the coordinates of the end of the stroke, and does not control the trajectory between the points, so there is no relationship between the movements of several coordinate axes. Several coordinates can move to the target point at the same time, or each coordinate can move in turn.

This kind of CNC machine tools mainly include CNC coordinate boring machine, CNC drilling machine, CNC punching machine, CNC spot welding machine, etc. The numerical control device of point position control CNC machine tool is called point position numerical control device.

1. Linear control CNC machine tool

The linear control CNC machine tool can control the tool or worktable to move and cut along the direction parallel to the coordinate axis with appropriate feed rate. The feed rate can change in a certain range according to the cutting conditions.

Linear control of the simple CNC lathe, only two coordinate axes, can process step axis. CNC milling machine with linear control has three coordinate axes, which can be used for plane milling. Modern modular machine tool adopts CNC feed servo system to drive the axial feed of power head with multiple axle boxes for drilling and boring. It can also be regarded as a kind of linear control CNC machine tool.

1. Contour control CNC machine tool

The contour control CNC machine tool can continuously control the displacement and speed of two or more motions, so that the resultant planar or spatial motion trajectory can meet the requirements of the part contour. It can not only control the coordinates of the starting point and the end point of the moving parts of the machine tool, but also control the speed and displacement of each point of the whole machining contour, so that the workpiece can be processed into the required contour shape.

3、 Classification according to characteristics of driving device

1. Open loop control CNC machine tool

The control system of this kind of CNC machine tool has no position detecting element, and the servo driving parts are usually reaction stepping motor or hybrid servo stepping motor. When the CNC system sends out a feed command, after the power amplification of the driving circuit, the stepping motor is driven to rotate for an angle, and then the screw is driven to rotate by the gear reducer, which is converted into the linear displacement of the moving parts through the screw nut mechanism. The velocity and displacement of moving parts are determined by the frequency and number of input pulses. The information flow of this kind of CNC machine tool is unidirectional, that is, after the feed pulse is sent out, the actual moving value is no longer fed back, so it is called open-loop control CNC machine tool.

1. Closed loop control of CNC machine tools

Then the actual displacement of the worktable is detected, the measured actual displacement value is fed back to the numerical control device, and compared with the input command displacement value, the difference value is used to control the machine tool, so that the moving parts move according to the actual displacement required, and finally realize the accurate movement and positioning of the moving parts. Theoretically speaking, the motion accuracy of the closed-loop system mainly depends on the detection accuracy of the detection device, and has nothing to do with the error of the transmission chain, so its control accuracy is high. Figure 1-3 shows the system block diagram of closed-loop control CNC machine tool. In the figure, a is speed sensor and C is linear displacement sensor. When the displacement command value is sent to the position comparison circuit, if the table does not move, there is no feedback. The command value makes the servo motor rotate. The speed feedback signal is sent to the speed control circuit through a, and the actual displacement of the workbench is fed back through C. the position comparison circuit is compared with the displacement command value, and the difference value obtained after comparison is used for position control Until the difference is zero. This kind of control CNC machine tool is called closed-loop control CNC machine tool because the machine table is included in the control link.

The lubrication system of CNC machine tool is intermittent oil supply mode. Therefore, the pressure in the lubrication system is checked regularly, that is, after each operation of the lubricating pump. If there is a fault, such as oil leakage, oil pump failure, oil pipeline blockage, the pressure in the lubrication system will suddenly drop or rise. At this time, the machine tool should be forced to stop running immediately for inspection, so as to avoid the expansion of the situation. The conventional way to deal with the low oil level is to classify the “low oil level” signal and the “abnormal pressure” alarm signal as an emergency stop signal. Once the PMC system receives the above signal, the machine tool will enter the emergency stop state immediately, and the servo system will be powered off at the same time. However, the lubrication system is caused by blockage or oil leakage“

In addition to the characteristics of ordinary milling machine processing, large computer gong processing also has the following six functional advantages:

1. Parts processing has strong adaptability and flexibility, and can process parts with complex contour shape or difficult to control size, such as mold parts, shell parts, etc;
2. It can process parts that can not be processed or difficult to process by ordinary machine tools, such as complex curve parts described by mathematical model and 3D curved surface parts;
3. It can process parts that need to be processed in multiple processes after one clamping and positioning;
4. The pulse equivalent of CNC device is generally 0.001mm, and the high-precision CNC system can reach 0.1 μ M. in addition, the CNC machining also avoids the operator’s error;
5. The production automation degree is high, can reduce the labor intensity of the operator. It is conducive to the automation of production management;
6. Because of the high production efficiency, CNC milling machine generally does not need to use special fixture and other special process equipment. When changing the workpiece, it only needs to call the processing program, clamping tool and tool adjustment data stored in the CNC device, thus greatly shortening the production cycle. Secondly, CNC milling machine has the functions of milling machine, boring machine and drilling machine, which makes the working procedure highly centralized and greatly improves the production efficiency. In addition, the spindle speed and feed speed of CNC milling machine are stepless, so it is helpful to select the best cutting parameters;

For the processing part is a frame plane or unequal height of all levels of steps, then the point – line system of CNC milling machine can be selected. If the machining part is a curved surface contour, two coordinate linkage system and three coordinate linkage system should be selected according to the surface geometry. According to the requirements of parts processing, CNC dividing head or CNC rotary table can be added on the basis of general CNC milling machine. At this time, the system of machine tool is four coordinate CNC system, which can process spiral groove, blade parts, etc.

Processing size of computer gong

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.

Production types are generally divided into three categories:

1. Single piece production: products with different structures and sizes are produced individually, and rarely repeated.
2. Batch production: the same products are manufactured in batches in a year, and the manufacturing process has certain repeatability
3. Mass production: a large number of products are manufactured, and most workplaces often repeat a certain process of a certain part. (1) The designed process specification shall ensure the processing quality of machine parts (or the assembly quality of the machine) and meet the technical requirements specified in the design drawing.

(2) It is necessary to make the technological process have higher productivity and put the products on the market as soon as possible.

(3) Try to reduce manufacturing costs

(4) Pay attention to reduce the labor intensity of workers to ensure the safety of production.

(1) Product assembly drawing, part drawing.

(2) Product acceptance quality standards.

(3) Annual production program of products.

(5) The production conditions of the manufacturer include the specifications, performance and current status of machine tool equipment and process equipment, the technical level of workers, the ability of self-made process equipment, and the power supply and gas supply capacity of the factory.

(6) Design manual and relevant standards required for process planning and process equipment design.

(7) Advanced manufacturing technology data at home and abroad.

Steps:

(1) Analyze and study the assembly drawing and part drawing of the product.

(2) Determine the blank.

(3) Draw up the technological route and select the base plane.

(4) Determine the equipment used in each process.

(5) Determine the tools, fixtures, measuring tools and auxiliary tools used in each process.

(6) Determine the technical requirements and inspection methods of each main process.

(7) Determine the machining allowance of each process, calculate the process size and tolerance.

(8) Determine the cutting parameters.

(9) Determine the man hour quota.

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 benchmark: the benchmark used in the process of parts processing and assembly. Dongguan computer gong processing, Dongguan Mechanical parts processing, Dongguan precision computer gong processing, Dongguan high-speed computer gong processing are called process benchmarks. 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. For the surface (or line, point) as positioning reference, only the rough surface can be selected in the first working procedure. This positioning surface is called rough datum. The machined surface can be used as the positioning datum in the following processes, and the positioning surface is called the precise datum.

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 plane is 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.

Fuselage part:

1) Casting, which is the most important part of computer gongs, directly affects the accuracy, stability, wear resistance and the life of machine tools. After the casting is finished, Dongguan computer gong processing is not immediately used in production. A good casting is that it is subjected to wind and rain, sunlight exposure, natural weathering, and some of them are soaked in sea water. After the casting does not change, the machine tool is not easy to change and can maintain the stability and accuracy of the machine tool for a long time.

2) Spindle, the spindle is used to directly face the workpiece. It is driven by the motor to rotate at a high speed. If the tool holder is installed on the spindle, the workpiece can be cut to meet various production needs. The quality of the spindle will also directly affect the machining accuracy. If the internal bearing is worn, it will easily cause the spindle to swing, and the accuracy of the processed things will naturally have a deviation of several wires 。 At present, the speed of the spindle is generally around 8000 rpm, and the high-speed machine can achieve more than 20000 revolutions. Each machine has only one spindle.

3) The screw rod is also a part of the machine body. It is driven by a servo motor to drive the displacement of the worktable through the copper sleeve of the screw rod to realize the processing needs. If there is a gap in the screw rod, it is also directly reflected in the machining accuracy and finish.

4) There are two kinds of motors: servo motor and frequency conversion motor. Servo motor has good stability, high power of spindle drive motor, and low coordination rate of three-axis drive motor.

5) The coupling is installed between the screw rod and the motor, which is only a linkage action.

6) The lubrication and cooling system is composed of automatic oil pump, spindle oil cooler and chip fluid circulation system. When the machine tool is working, the oil is pumped once a few minutes, and the oil pipe is connected to each corner, such as screw rod, guide rail, etc. if the oil circuit is blocked, it is easy to cause the guide rail wear and affect the accuracy. The main shaft oil cooling is a circulating cooling system added to cool down the main shaft. The spindle with 8000 revolutions may not be required, and the spindle with more than 8000 revolutions must be equipped. The oil in the oil tank is pumped up by the pumping motor in the chip liquid circulation system to flush the workpiece being processed.

7) Sheet metal, sheet metal requirements are not too high, as long as there is no oil leakage, but also involves the appearance of beautiful, image problems.

Whether it is a stamping die or a plastic mold (including injection mold, extrusion mold, blow molding mold, etc.), in order to improve its service life, the parts that constitute the mold cavity are generally made of high-strength wear-resistant materials (such as various brands of alloy structural steel, alloy tool steel and stainless steel, etc.). The hardness of these materials after heat treatment is very high, so it is difficult to use conventional mechanical processing Methods processing. For decades, the best way to deal with this kind of difficult to machine materials is to use special processing.

In China, mold cavity machining is still the “one country” of EDM. EDM (including forming and wire cutting) has been playing a very important role in mold manufacturing.

With the development of production and the speed of product renewal, higher and higher requirements are put forward for the production efficiency and manufacturing quality of mould, so the problems existing in EDM are gradually exposed. From the physical essence, Dongguan precision computer gongs machining EDM is a kind of “micro cutting” process relying on discharge ablation, the processing process is very slow; in the process of partial high temperature discharge ablation of the workpiece surface by EDM, the physical mechanical properties of the workpiece surface will be damaged to a certain extent, and micro cracks and surface roughness will often occur on the surface of the cavity It can not meet the requirements of the mold, so the cavity parts after electrical machining generally have to be ground and polished manually. Therefore, the production efficiency of EDM is very low and the manufacturing quality is unstable. In many occasions, mold has become a key factor affecting the development speed of new products.

Since the 1990s, high speed machining (HSC) has been gradually applied in the mold industry abroad, and good results have been achieved. Compared with EDM, the main advantages of high speed machining are as follows

Good product quality: high speed cutting can process parts at a cutting speed about 10 times higher than the conventional cutting speed, The blank material is cut off from the workpiece in an instant before it is fully deformed, and the residual stress on the surface of the workpiece is very small; most of the heat generated in the cutting process (more than 95) is quickly taken away by the chips, and the thermal deformation of the workpiece is small; in the high-speed machining process, the main shaft of the machine tool operates at a very high speed (10000-80000r / min), and the excitation frequency is far away from “machine tool” The natural frequency range of the “tool workpiece” system makes the machining process of the parts stable without impact. Therefore, the machining precision of the parts is high, the surface quality is good, and the roughness can reach ra0.6 μ M. After high-speed milling cavity, the surface quality of Dongguan high-speed computer gong machining can reach the grinding level, so many subsequent finishing processes can be omitted.

High production efficiency: using high-speed machining center or high-speed milling machine to process mold can complete rough and finish machining of cavity and other parts of mold parts in one clamping of workpiece, which is called “one pass machining”. The cutting speed is very high, and the efficiency of machining process itself is several times higher than that of electrical machining. except