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High gloss traceless mold – brain Gong processing

Main features of high gloss and no trace die:

First, the mold forming temperature is higher. At higher mold temperature, injection molding can eliminate weld mark, flow mark, internal stress and other defects. Therefore, the mold needs to be heated when it is working. In order to prevent heat loss, the resin heat shield is usually added on the fixed mold side;

Second, the cavity surface is extremely bright (generally mirror 2 or higher). The products produced by high gloss mold can be directly used to assemble the whole machine without any surface treatment, so this process has high requirements for mold steel and plastic materials;

Thirdly, there are many hot nozzles in hot runner system (generally 6-8 nozzles, sometimes more). Each nozzle must be equipped with a sealing needle and an independent air passage, which can be controlled separately by solenoid valve and timing controller to realize time-sharing glue feeding, so as to achieve control and even eliminate weld marks.

High gloss traceless injection molding technology has some basic requirements for molds

The inner surface of the mould requires very high finish to ensure the surface quality of the products. The setting of pipes inside the mould must be reasonable to ensure rapid heating and cooling. The pipe inside the mold should have good thermal conductivity. Due to the need to keep heating and cooling in the production process, the mold needs to choose high-quality steel. In the process of use, we should pay special attention to the maintenance of the mold to ensure that it is dry and dust-free.

In addition, the performance and service life of high gloss traceless mold are directly related to the steel used in the mold. Due to different working conditions of plastic mold parts, the external influence is also different. Therefore, in addition to the basic requirements, the steel should also be emphasized. For example, large high gloss plastic mold cavity steel, in addition to the requirements of good cutting, EDM and welding performance, also need to have excellent throwing rotation and high hardness and other characteristics. This can not only form a bright and beautiful product, but also reduce the wear of plastic on the cavity surface, which not only extends the service life of the mold, but also reduces the injection pressure and protects the injection molding machine. At present, the high-performance and high gloss non marking die steels used in different processing conditions of flat-panel TV include polmax, lkm838h, lkm818h, s-star (a), NAK80, Stavax S136, Stavax s136h, Optimax, x13t6w (236), x13t6w (236h), etc.

Application in the field of home appliances

In recent years, the traditional CRT TV in the TV industry has been gradually eliminated, and replaced by the flat-panel TV with novel appearance, thin volume and high-grade visual sense. The surface quality of the front shell directly affects the grade of the flat-panel TV. However, the TV front shell produced by the traditional mold is difficult to eliminate the defects such as the surface weld mark and the surface finish is not enough, which can not achieve the beautiful effect. Therefore, it also needs to go through the secondary processing such as surface coating, which brings the problems such as the lengthening of the TV manufacturing cycle and the rising of the manufacturing cost.

High gloss traceless mold can solve the above problems of traditional mold. High gloss traceless mold technology has been rapidly applied in the home appliance industry since it was officially announced in the 2004 German rubber and plastic Exhibition: in 2005, Samsung of South Korea began to use high gloss mold technology to produce LCD TV shell, Chinese TV manufacturers also began to carry out the application research of this technology in 2006, and began to widely use it in the production of flat panel TV shell in 2008.

Computer gong processing machine 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 computer gong NC machining is the basis of modern manufacturing technology, this invention for the manufacturing industry, has epoch-making significance and far-reaching influence.

Introduction of CNC machining center coordinates

Machining center is often divided into vertical machining center and horizontal machining center according to the state of the spindle in the space. The vertical machining center whose spindle is vertical in the space is called vertical machining center, and the horizontal machining center whose spindle is horizontal in the space is called horizontal machining center. Spindle can be vertical and horizontal conversion, known as vertical and horizontal machining center or five machining center, also known as composite machining center. According to the number of machining center columns, there are single column type and double column type (gantry type).

According to the coordinate number of machining center movement and the coordinate number of simultaneous control, there are three axis two linkage, three axis three linkage, four axis three linkage, five axis four linkage, six axis five linkage, etc. Three axis and four axis refers to the number of motion coordinates of the machining center. Linkage refers to the number of coordinates that the control system can control at the same time, so as to realize the position and speed control of the tool relative to the workpiece. Machining center is often divided into vertical machining center and horizontal machining center according to the state of the spindle in the space. The vertical machining center whose spindle is vertical in the space is called vertical machining center, and the horizontal machining center whose spindle is horizontal in the space is called horizontal machining center. Spindle can be vertical and horizontal conversion, known as vertical and horizontal machining center or five machining center, also known as composite machining center. According to the number of machining center columns, there are single column type and double column type (gantry type).

CNC computer gong processing sequence

1、 Face before hole

For the box, bracket and connecting rod, the plane should be machined first and then the hole should be machined

In this way, the hole can be processed by plane positioning to ensure the orientation accuracy of the plane and the hole, and bring convenience to the processing of the hole on the plane.

2、 Machining datum first

Parts in the processing process, as a positioning reference surface should be processed first, in order to provide fine reference for the subsequent process as soon as possible. It is called “benchmark first”.

3、 Finishing

The main surface finishing (such as grinding, honing, finishing, rolling, etc.).

It should be carried out in the final stage of the process road. The surface finish after processing is above ra0.9um. Slight bumps will damage the surface. In Japan, Germany and other countries, after finishing, flannelette should be used for maintenance. It is definitely forbidden to touch the workpiece directly by hand or other objects to avoid damage to the surface of finishing due to the transfer and device between processes.

4、 Distinguish processing stages

The appearance with high processing quality requirements can be divided into three stages: rough processing, semi finishing and finishing. First of all, it is to ensure the processing quality; it is conducive to the rational use of equipment; it is convenient to organize the heat treatment process; and it is convenient to find the defects of blank.

Introduction of CMM for CNC machining

This paper introduces the development of three coordinate measuring instrument, which is a new type of high efficiency precision measuring instrument developed in recent 30 years. It is widely used in mechanical manufacturing, electronics, automotive and aerospace industries. It can detect the size, shape and mutual position of parts and components, such as box, guide rail, turbine and blade, cylinder block, cam, gear shape and other space surface measurement. In addition, it can also be used for scribing, centering hole, photolithography integrated circuit, etc., and can scan continuous curved surface and prepare machining program of CNC machine tool. Because of its versatility, wide measurement range, high precision, high efficiency, good performance, and can be connected with flexible manufacturing system, it has become a kind of large precision instrument.

With the development of CMM market, CMM, as a modern large-scale precision instrument, has shown its importance and broad development prospects. It can measure the three-dimensional dimension of space conveniently and realize on-line detection and automatic measurement.

Its advantages are as follows:

It has strong versatility, can realize the measurement of spatial coordinates, and can easily measure the three-dimensional outline size and position accuracy of various parts;
The measurement is accurate and reliable
It is convenient for data processing and program control. Therefore, it can be incorporated into automatic production and flexible processing line, and become an important part. At present, CMM is developing rapidly at home and abroad. Famous foreign manufacturers include Zeiss and Leitz of Germany, DEA of Italy, Brown & Sharpe of America, Mitutoyo of Japan, etc. Since the development of CMM in 1970s, great progress has been made in China. The main manufacturers in China are China Aerospace Precision Machinery Research Institute, Qingdao Qianshao yingkefa measuring equipment Co., Ltd., Shanghai machine tool factory, Beijing Machine Tool Research Institute, Harbin Measuring Tool and cutting tool factory, Kunming Machine Tool Factory and Xintian optical instrument factory, etc. At present, China has the ability to produce hundreds of various types of CMM annually. With the development of various industries, the development of coordinate measuring instruments will also be rapid. Many small manufacturers choose second-hand CMM because they can’t afford to buy the new CMM, so the price is more favorable, and they can also use the new type of CMM imported work.

Introduction of vertical CNC lathe

(1) Vertical CNC lathe vertical CNC lathe referred to as CNC vertical lathe, the lathe spindle is vertical to the horizontal plane, a large diameter circular worktable, used to clamp the workpiece. This kind of machine tool is mainly used for processing large complex parts with large radial size and relatively small axial size.

(2) Horizontal NC lathe horizontal NC lathe is divided into NC horizontal guide horizontal lathe and NC inclined guide horizontal lathe. The inclined guide rail structure can make the lathe more rigid and easy to remove chips.

Classification according to the basic types of machined parts

(1) Chuck type CNC lathe has no tailstock, which is suitable for turning disc (including short shaft) parts. The clamping mode is mostly electric or hydraulic control, and the chuck structure has adjustable claw or non quenched claw (soft claw).

(2) This kind of lathe is equipped with ordinary tailstock or CNC tailstock, which is suitable for turning long parts and disc parts with small diameter.

According to the number of turrets

(1) Single turret CNC lathe is generally equipped with various forms of single turret, such as four position horizontal rotation turret or multi position turret automatic rotation turret.

(2) Double turret CNC lathe this kind of lathe double turret configuration parallel distribution, can also be mutually vertical distribution.

By function

(1) The simple CNC lathe, which is formed after the feed system of ordinary lathe is transformed by stepping motor and single chip microcomputer, has low cost, but the degree of automation and function are relatively poor, and the turning accuracy is not high. It is suitable for the turning of rotary parts with low requirements.

(2) According to the turning requirements, the general CNC lathe is specially designed in structure and equipped with general CNC system. The CNC system has strong function, high degree of automation and machining accuracy, and is suitable for turning general rotary parts. The CNC lathe can control two coordinate axes, namely X axis and Z axis.

(3) On the basis of ordinary CNC lathe, turning center adds c-axis and power head. More advanced CNC lathe has tool magazine, which can control x, Z and C coordinate axes. Linkage control axes can be (x, z), (x, c) or (Z, c). Due to the addition of c-axis and milling power head, the machining function of this CNC lathe is greatly enhanced. In addition to general turning, it can be used for radial and axial milling, surface milling, drilling of holes and radial holes whose center line is not in the rotation center of parts.

CNC precision machining circuit

When the machining precision of ultra precision parts is nanometer, or even atomic unit (atomic lattice distance is 0.1 ~ 0.2 nanometer), the machining method of ultra precision parts can not adapt to it. It needs to use the method of special precision parts machining, that is, the application of chemical energy, electrochemical energy, thermal energy or electric energy, to make these energies exceed the binding energy between atoms, so as to remove the surface defects In order to achieve the goal of ultra precision machining, some atoms are attached, combined or lattice deformed. This kind of processing includes mechanical chemical polishing, ion sputtering and ion implantation, electron beam exposure, laser beam processing, metal evaporation and molecular beam epitaxy.

The characteristic of these ultra precision parts machining methods is that the amount of material removed or added to the surface layer can be controlled very finely. However, to obtain the machining accuracy of ultra precision parts, it still depends on precision machining equipment and precise control system, and uses ultra precision mask as the intermediary. For example, in VLSI plate making, electron beam is used to expose the photoresist (see lithography) on the mask to make the atoms of the photoresist polymerize (or decompose) directly under electron impact, and then the polymerized or unpolymerized parts are dissolved by the developer to make the mask. Electron beam exposure plate making requires ultra precision processing equipment with positioning accuracy of ± 0.01 micron.

General principles for drawing up process route of precision parts

There are two steps in the process planning of precision parts. First of all, draw up the process route of parts processing, and then determine the process size of each process, the equipment and process equipment used, as well as the cutting specification, man hour quota, etc. These two steps are interrelated and should be comprehensively analyzed.

The process route of precision parts processing is to make the overall layout of the process. The main task is to select the processing method of each surface, determine the machining sequence of each surface, and the number of processes in the whole process.

General principles of process planning

Machining datum first

In the machining process of parts, the surface as the positioning datum should be machined first, so as to provide the precise datum for the subsequent process as soon as possible. It is called “benchmark first”.

Division of processing stages

Machining quality requirements of the surface, are divided into processing stages, generally can be divided into rough machining, semi finishing and finishing three stages. The main purpose is to ensure the processing quality, to facilitate the rational use of equipment, to facilitate the arrangement of heat treatment procedures, and to facilitate the detection of blank defects.

Face before hole

For parts such as box, bracket and connecting rod, the plane should be machined first and then the hole should be machined. In this way, the hole can be machined by plane positioning, the position accuracy of the plane and the hole can be ensured, and the machining of the hole on the plane is convenient.

Details of CNC machining miscellaneous parts

The parameters of the front center gear are: modulus M = 4, number of teeth z = 9, addendum height coefficient ha = 1, addendum clearance coefficient C = 0.25, radial modification coefficient X = 0.4, number of teeth k = 2, common normal wn = 19.5 + 0.2 + 0.1 (mm). CAXA does not provide professional gear modeling command and can model through function curve, but this method is more cumbersome and more difficult with modification coefficient.

It is difficult to guarantee the size of the curve groove at the lower end of the front side of the part, and the two 90 ° notches are not closed, so it is necessary to close the auxiliary line before programming.

There are two ellipses in different directions on the inner contour edge of the back, inner and outer hexagonal petals composed of arcs in the center, and two arc curve islands at the top and bottom. These elements need to be rounded in processing, so it is more convenient to choose a reasonable shape.

Analysis of parts processing technology

Using CAXA to manufacture engineering parts, there is no need to draw a complete part for reprocessing. Firstly, the downtime is long and the processing time is wasted. Secondly, when selecting local processing, the elements between parts will interfere, which is not convenient to draw the program track.

The software supports rough and finish machining only by drawing the contour line of the part when machining the plane contour elements. Surface machining can be programmed by solid or surface. In order to realize local machining, curved surface must be used, and some finishing commands can only be selected by curved surface.

The rough machining command can not only realize rough machining, but also be used as finish machining command.

The finishing command can use the track translation to form multiple levels and connect the tracks into a whole rough machining command; the rough machining command can change a layer of processing track into a finishing command by setting the layer height.

The plane contour elements of CAXA Manufacturing engineer can use the plane area rough machining and contour finish machining to complete the rough and finish machining of parts, and can also use the contour finish machining to do the rough machining. Surface roughing can use contour roughing, parameter line finishing and three-dimensional offset surface finishing commands for roughing and finishing.

Due to the high dimensional accuracy in the drawing, it is decided to adopt rough machining, semi finishing and finishing to achieve dimensional accuracy. Semi finishing and finishing adopt the same cutting tools and cutting parameters, which can correct various geometric errors of the cutting tools and elastic deformation of the parts. It is easy to ensure the size, and finish machining is also required for the important bottom surface.

The part is processed by FANUC CNC machining center, all tool paths are generated according to FANUC post format, and transmitted by CAXA’s own communication function according to FANUC settings, and large surface programs are processed online; the later processing programming ends with tool path.

Essential knowledge for CNC machining workers

Master the processing principle and process. When using the common CNC machining technology, the processor should follow the principles of rough machining first, then finish machining, preventing the workpiece from thermal change, reducing vibration and so on. At the same time, also have the ability to deal with all kinds of unexpected problems, such as: how to adjust the tool speed.
Familiar with automatic or manual operation of CNC machining. The machinist should know clearly what process needs manual operation, what is the normal operation state of the machine tool when it is operated manually, what process is suitable for automatic operation, and what state the machine tool should be in. Professional CNC processing staff said, familiar with the above operation, help to carry out the processing work, and can deal with any situation freely.

The above is the basic skills of professional CNC processing personnel. Only by mastering these skills can we complete CNC processing operation independently. In order to become a qualified CNC machining worker, only by constantly asking questions and practicing in the work can we make our technology more solid.

Selection and use of CNC machining fixture

(1) According to the characteristics and processing needs of machining center, the commonly used fixture types include special fixture, modular fixture, adjustable fixture, group fixture and workpiece unified reference positioning clamping system.

(2) The high flexibility of machining center requires that its fixture structure is more compact and simple than ordinary machine tool, clamping action is more rapid and accurate, auxiliary time is reduced as far as possible, operation is more convenient, labor-saving and safe, and enough rigidity and flexibility should be ensured. Therefore, pneumatic and hydraulic clamping devices are often used.

(3) In order to keep all the surfaces to be machined fully exposed, the fixture should be open as far as possible, and the space position of the clamping element should be low as possible, so there must be space for the tool path.

(4) Considering the minimum distance between the machine tool spindle and the worktable and the clamping length of the tool, the installation position of the fixture on the machine tool worktable should ensure that the processing content of the workpiece can be completed within the stroke range of the spindle.

(5) Automatic tool change and worktable exchange can not interfere with the fixture or workpiece.

(6) Sometimes, the positioning block on the fixture is used when installing the workpiece. In the process of processing, in order to meet the processing requirements of the front, back, left and right stations and prevent interference, the workpiece can be removed after clamping. In this regard, we should consider the problem of maintaining the positioning accuracy of the workpiece after removing the positioning element.

(7) Try not to change the clamping point in the middle of machining.

(8) Determine the best position of parts on the machine tool table