Category Archive Machinery industry

NC machining G code language tells CNC machine tool which Cartesian position coordinates, and controls the tool feed speed and spindle speed, as well as tool converter, coolant and other functions. Compared with manual machining, CNC machining has great advantages, such as the parts produced by CNC machining are very accurate and repeatable; CNC machining can produce parts with complex shapes that cannot be completed by manual processing. CNC machining technology has been widely promoted, most of the machining workshops have the ability of NC machining. The most common NC machining methods in typical machining workshops are CNC milling, CNC lathe and CNC EDM wire cutting (WEDM). The tool for NC milling is called CNC milling machine or CNC machining center. CNC turning lathe is called CNC lathe center. NC machining G code can be manually programmed, but usually the machining workshop uses CAM software to automatically read CAD file and generate G code program to control NC machine tool. Leading CNC machine tool brands include Hass, DMG (Deckel MAHO GILDEMEISTER), Mazak, Mori Seiki, fadal and wasino.

Several groups of common instructions for CNC machining

1、 Pause instruction g04x (U)_ /P_ It refers to the tool pause time (feed stop, spindle does not stop), the value after address P or X is the pause time. The value after X should have a decimal point. Otherwise, it should be calculated by one thousandth of this value in seconds (s). The value after P cannot have a decimal point (i.e., an integer), and the unit is Ms. For example, G04 x2.0; or G04 X2000; pause for 2 seconds G04 P2000; but in some hole series processing instructions (such as g82, G88 and g89), in order to ensure the roughness of the hole bottom, when the tool is machined to the hole bottom, there must be a pause time, which can only be expressed by the address P. if the address x is used, the control system thinks that x is the x-axis coordinate value for execution. For example, g82x100.0y100.0z-20.0r5.0f200p2000; drilling (100.0100.0) to the bottom of the hole for 2 seconds; g82x100.0y100.0z-20.0r5.0f200x2.0; drilling (2.0100.0) to the bottom of the hole will not be suspended.

2、 The difference and connection of M00, M01, M02 and M30 are program unconditional pause instructions. When the program is executed, the feed stops and the spindle stops. To restart the program, you must first return to the og state, press CW (spindle forward rotation) to start the spindle, and then return to the auto state and press the start key to start the program. M01 is the program selective pause instruction. The op stop key on the control panel must be opened before the program is executed. The effect after execution is the same as that of M00. Restart the program as above. M00 and M01 are often used in the inspection or chip removal of workpiece size in the process of machining. M02 is the end instruction of main program. Execute this command, feed stop, spindle stop, coolant off. But the program cursor stops at the end of the program. M30 is the main program end instruction. The function is the same as that of M02, except that the cursor returns to the program head position, regardless of whether there are other program segments after M30.

3、 The meaning of the address D and H is the same. The tool compensation parameters D and H have the same function and can be interchanged arbitrarily. They all represent the address name of the compensation register in the CNC system, but the specific compensation value is determined by the compensation number address behind them. However, in order to prevent errors in the machining center, generally, h is the tool length compensation address, the compensation number is from No. 1 to No. 20, D is the tool radius compensation address, and the compensation number starts from No. 21 (tool magazine of 20 tools). For example, g00g43h1z100.0; g01g41d21x20.0y35.0f200;

4、 Mirror instruction mirror processing instruction M21, M22, M23. When only the x-axis or y-axis is mirrored, the cutting sequence (forward milling and reverse milling), cutter compensation direction and circular interpolation steering will be opposite to the actual program. When the x-axis and y-axis are mirrored at the same time, the tool feed sequence, tool compensation direction and circular interpolation direction remain unchanged. Note: after using the mirror instruction, M23 must be used to cancel, so as not to affect the following program. In G90 mode, if mirror or cancel command is used, it can be used only after returning to the origin of workpiece coordinate system. Otherwise, the NC system can not calculate the motion track behind, which will lead to the phenomenon of random tool walking. At this time, it is necessary to implement manual origin reset operation to solve the problem. The spindle rotation does not change with the mirror command.

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?

In the latter, it is the most important to prepare the whole machining process, and the most important thing for the latter is to finish the machining process according to the machining process 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.

The touch of the first generation iPad back shell with CNC technology has a certain particle sense. In terms of internal design, the internal performance of the first generation iPad back shell is relatively rough, the fixation method of internal screws and the design of “baffle” are relatively abrupt, and the overall design sense of the back shell is poor. However, the existence of the stripe design can better provide space for components and ensure the performance of the product. The thickening design at the back shell key position can ensure the fixed mode of the function key to a certain extent.

In addition, the internal screw fixing method and “baffle” design of the iPad using CNC technology are more prominent. It can be seen that the preliminary CNC process applied to flat products is still relatively rough. There are still many areas to be improved in the internal design. However, the strict product precision and outstanding texture make the process superior to the injection molding and stamping molding process. Of course, this is only the initial CNC process, so what progress has been made in this process? Let’s go on to look.

CNC processing technology tends to be mature. Nokia N1 and iPad air2 adopt this technology. With the development of CNC technology, more and more tablet products are applied. The most representative ones are Apple’s latest series of tablet ipadir2 and Nokia N1 tablet computer. Both of these two products adopt CNC technology on the back shell. What are the improvements in technology and design?

Nokia N1 uses the latest CNC technology back shell, which improves the process and makes the appearance more beautiful. In terms of CNC processing, the products made by this process are more “slim”, the overall visual and sensory impact of the back shell is enhanced, and the product appearance becomes more exquisite (of course, this is also related to the upgrading and improvement of the screen), and the surrounding border becomes more rounded, not a rigid “frame” shape Design, more comfortable to hold, the change can be said to be a technological improvement.

Nokia N1 peripheral border becomes more rounded, not a rigid “frame” design. In addition, there are some improvements in the details of the key position, so that the key position does not stay on the side border, but is close to the back plate to a certain extent. In this way, the thickness of the body is reduced and the user’s operation is not affected. It can be said that killing two birds with one stone. To a certain extent, the realization of the design also depends on the improvement of the process.

The details of the key position are also improved to facilitate operation, but also more beautiful. The concave design of the interface has also been improved in the previous technology. There is a certain gap between the two key positions. The design makes the volume key position and the shutdown key set adjacent, which makes the side of the machine more beautiful.

The precision of CNC process perfectly supports the design with the close distance between two key positions. It can be seen that the appearance of today’s CNC technology has been greatly improved compared with that before. The round frame, more refined appearance and more mature grinding technology are available. The high-precision grinding fuselage will have a kind of industrial design aesthetic feeling. But these are only the improvement of appearance process, so whether the inner process of the back shell is also improved? Please go on to see.

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 die and 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 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. 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. For the surface (or line, point) processed by CNC 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 reference in the following processes, 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.

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, the high-speed computer gong processing is equipped with independent lubrication device, and the lifting is driven by ordinary reducer with 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.

The design of vacuum suction molding mold includes batch size, molding equipment, precision conditions, geometric design, dimensional stability and surface quality. Properties and surface quality.

1. Batch size experiments, mold production hours, can be made of wood or resin. However, if the mold used in the experiment is to obtain the data of shrinkage, dimensional stability and cycle time of the product, the single cavity mold should be used for the experiment, and it can be used in the production conditions. Molds are generally made of gypsum, copper, aluminum or aluminum steel alloys, and aluminum resin is rarely used.
2. In geometric design, dimensional stability and surface quality should be considered comprehensively. For example, the product design and dimensional stability require the use of female die (female mold), but the product with high surface gloss requires the use of male mold (punch). In this way, the ordering party of plastic parts will take these two points into consideration, so that the product can be produced under the best conditions. Design failure is often proved by experience. As a special process equipment with high service life, mould has the following production characteristics:

(1) It belongs to single piece and multi variety production. Mold is a special process equipment with high life. Each die can only produce parts of a certain shape, size and precision, which determines that mold production belongs to the nature of single piece and multi variety production rules.

(2) The objective requirement of mould production cycle is short. At present, due to the acceleration of new product upgrading and market competition, mold production cycle is required to be shorter and shorter objectively. The production management, design and process of die should meet the objective requirements.

(3) Complete set of mould production. When a part needs more than one pair of molds to process, each pair of molds often implicate and influence each other. Only when the final part is qualified, this series of molds can be considered as qualified. Therefore, this feature must be fully considered in production and planning.

(4) Mold test and repair. Because of the above characteristics of mold production and the experience of mold design, the mold must pass the test punching or pressure test after assembly, and finally determine whether it is qualified; at the same time, some parts need to be repaired before final determination. Therefore, there must be a certain trial period in the production schedule.

(5) Mold processing is developing towards mechanization, precision and automation. At present, the requirement of die precision for product parts is higher and higher. There are more and more molds with high precision, high life and high efficiency. The machining accuracy mainly depends on the accuracy of machine tools, processing conditions, measurement means and methods. At present, the use of precision molding grinder, CNC high-precision surface grinder, precision CNC WEDM machine, high-precision continuous track coordinate grinder and CMM are becoming more and more popular, which makes mold processing develop to high-tech intensive.

Because different molding molds have been applied in many fields, and the manufacturing technology of professional molds has also changed and developed in recent years, the general design rules of vacuum Blister molding molds are summarized in this part.

The design of vacuum suction molding mold includes batch size, molding equipment, precision conditions, geometry design and dimensional stability

1. During the molding process, the dimension stability of the contact surface between the plastic part and the mold is better than that of the part leaving the mold. If the material thickness is required to be changed due to the requirement of material stiffness in the future, it may lead to the conversion of male mold to female mold. The dimensional tolerance of plastic parts shall not be less than 10% of shrinkage.
2. The surface structure of the plastic part should be formed at the contact with the mold in terms of the range covered by the molding material. If possible, the polished surface of the plastic part should not contact the mold surface. It’s like using a female mold to make bathtubs and washbasins.
3. If mechanical horizontal saw is used to saw off the clamping edge of plastic parts, there should be at least 6-8mm allowance in the height direction. Other finishing work, such as grinding, laser cutting or jet, must also be allowed. The gap between cutting lines of knife edge die cutting is the smallest, and the distribution width of trimming punching die is also very small.
4. Shrinkage and deformation, plastic is easy to shrink (e.g. PE), some plastic parts are easy to deform, no matter how to prevent, plastic parts will deform in the cooling stage. In this condition, it is necessary to change the shape of the mold to adapt to the geometric deviation of the plastic part. For example, although the wall of the plastic part remains straight, its reference center has deviated by 10 mm; the mold base can be raised to adjust the shrinkage of this deformation.
5. Shrinkage, the following shrinkage factors must be considered when manufacturing Blister molding mold.

1. First, clean the bearing in gasoline and wipe off the oil sludge and dust left on the bearing. All bearings with rust are gently polished with metallographic sandpaper until there is no roughness by hand.
2. Dry the cleaned bearings with dry rags, and then soak them in antirust oil. In the process of CNC machining, the bearing should be completely contacted with the antirust oil, and the bearing should not be stopped. Only in this way can the oil film formed by the antirust oil cover the surface of the bearing and achieve the purpose of antirust.
3. Next, apply lithium grease and grease evenly on the surface of the bearing, including inner and outer rings, wheels and cages. And it is to wipe while rotating the bearing, so that the grease really into the bearing, play a full role in lubrication.

There are many ways to obtain the accuracy of measuring workpiece size in machining, one of which is the trial cutting method. What is its main operation?

That is, first try to cut out a small part of the machined surface, measure the size of the trial cut, adjust the position of the cutting edge of the cutting tool relative to the workpiece according to the processing requirements, and then cut again by CNC machining, and then measure again. After two or three times of trial cutting and measurement, when the machined size meets the requirements, the whole surface to be machined can be cut. The trial cutting method is repeated until the required dimensional accuracy is achieved through “trial cutting – Measurement – adjustment – re cutting”. For example, trial boring of box hole system.

The precision of the trial cutting method may be very high, it does not need complex devices, but this method is time-consuming (need to make multiple adjustments, trial cutting, measurement, calculation), low efficiency, depends on the technical level of workers and the accuracy of measuring instruments, and the quality is unstable, so it is only used for single piece and small batch production.

As a type of trial cutting method matching, it is based on the processed parts, CNC machining another matching workpiece, or combining two (or more) workpieces for processing. The final dimension to be processed in the matching process is based on the matching requirements of the machined parts.

According to the different heating medium, heating temperature and cooling method, each category can be divided into several different heat treatment processes. The same metal with different heat treatment process can obtain different microstructure and different properties.

Steel is the most widely used metal in industry, and the microstructure of steel is also the most complex. Therefore, there are many kinds of heat treatment processes for steel.

Integral heat treatment is a metal heat treatment process that heats the workpiece as a whole and then cools it at a proper speed to change its overall mechanical properties. There are four basic processes of heat treatment of iron and steel: annealing, normalizing, quenching and tempering.

Annealing is to heat the workpiece to the appropriate temperature, adopt different holding time according to the material and size of the workpiece, and then cool it slowly. The purpose is to make the internal structure of the metal reach or close to the equilibrium state, and obtain good process performance and performance. Computer gong processing, Dongguan computer Gong processing, Shenzhen computer gong processing, mechanical parts processing, Guangzhou computer gong processing

Or to prepare for further quenching. Normalizing is to heat the workpiece to a suitable temperature and then cool it in air. The effect of normalizing is similar to that of annealing, but the microstructure is finer. It is often used to improve the cutting performance of low-carbon materials, and sometimes used as the final heat treatment for some parts with low requirements.

Quenching is the rapid cooling of the workpiece in water, oil or other inorganic salt, organic water solution and other quenching media after heating and holding. After quenching, the steel parts become hard but brittle at the same time. In order to reduce the brittleness of steel parts, the quenched steel parts are kept at a proper temperature higher than room temperature but lower than 650 ℃ for a long time, and then cooled. This process is called tempering. Annealing, normalizing, quenching and tempering are the “four fires” in the whole heat treatment. Quenching and tempering are closely related and often used together.

With the different heating temperature and cooling methods, different heat treatment processes have evolved. In order to obtain certain strength and toughness, quenching and high temperature tempering process is called quenching and tempering. Computer gong processing | Dongguan computer gong processing | Shenzhen computer gong processing | mechanical parts processing | Guangzhou computer gong processing

Some alloys are quenched to form supersaturated solid solutions, which are kept at room temperature or a little higher temperature for a long time to improve the hardness, strength or electrical magnetism of the alloys.

After the injection molding, the film and plastic are integrated. The wear-resistant material is on the outside. This process is mostly used in the mobile phone display screen. The plastic materials are mostly PC, PMMA, PBT, etc., which mainly have the function of wear resistance and scratch resistance. There is also a technology called IML (in-mold-lable), which is roughly the same as IMD, except that flim is pulled out like a punched tape after injection molding, which just transfers the printed pattern to the plastic parts, also known as in mold transfer.

There are two main types of IMD. One is PC and single chip. The other is pet, chain like (like film or printed instant noodle pockets).

The former finished product is merge PC chip, the latter only takes the ink on the pet chain, but PET material (chain, also known as foil) is not imported into parts by merge.

The former can only be screen printed because of the thick PC, so the effect is rough. For example, the front shield shape of Motorola v66 is already very delicate, while the latter can be printed with offset plate due to its thin pet, which is very fine, especially electroplating and transparent, fine metal and surface texture are very good, such as the front electroplating and black texture effect of Motorola V60.

For example, the control panel on Matsushita rice cooker mold is a typical IMD, which puts a silk screen printed PET film into the injection mold for injection molding. The materials are PC, transparent ABS and PMMA. After injection molding, the film and plastic are combined into one.

Nowadays, most of the outer screen lenses of mobile phones adopt IMD technology, and the cost is correspondingly increased. The requirements of mobile phone molds, especially transparent molds, are more stringent.

Generally speaking, there are two background reasons for using IMD,

1. Some effects of injection molding are difficult to simulate, such as the walnut automobile dashboard (car parts mold).
2. It is very difficult to integrate several effects on small pieces of parts. For example, the front triangle of moto V60 mold concentrates on electroplating, transparency and screen printing, but it also requires delicacy. Imagine that it is very difficult to use real plating, injection molding and splicing of transparent pieces.

Another method is to make the outer surface smooth and the inner surface rough, but there are some requirements for the mold.

In a broad sense, it refers to the process that all products can be manufactured by mechanical means; in a narrow sense, it refers to the process of making parts by 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.

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, 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 cannot meet the requirements, that is, the possibility of various original errors, and take effective technological measures to overcome them, So as to improve the machining accuracy.