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CNC machining of stainless steel

In order to increase the cross-sectional area of the hole cutter as much as possible, it is generally enough to leave 1-2mm cutting allowance in the radial direction. The cutter bar should be circular, the main cutting edge of the cutter is in the longitudinal section through the cutter bar axis, and the shorter the cutter bar length is, the better,

When grinding the arc flank of the inner hole cutter, great attention is paid to it. It is a place with high technical content in inner hole machining, and it is also the main aspect to solve the chatter pattern,

In fact, the above is basically about the upper level, and the most important thing is the tool grinding. If the tool grinding is not good, it is difficult to process qualified parts,

a. First of all, the materials of cutting tools are different for different parts. For stainless steel, red copper and brittle materials, tungsten cobalt type cutting tools should be used. For plastic materials such as carbon steel, tungsten cobalt titanium type cutting tools should be used. For materials with high hardness, YW series cutting tools should be used, that is, tungsten cobalt titanium tantalum niobium type cutting tools,

b. The most important point is that the grindability of grinding wheel and grinding wheel is better, and the rigidity of grinding wheel machine is better. It is better to have two grinding wheels, one with brown corundum wheel (grinding cemented carbide) and the other with white corundum wheel (grinding high speed steel). If the above two kinds of grinding wheels are installed on one grinding machine at the same time, it is difficult to grind the standard cutting tools.

Generally, the machining of stainless steel parts is to first process the outer circle and then the inner hole, because the deformation of the outer circle is smaller than that of the inner hole,
Stainless steel parts processing is a very practical work, it needs a long time of actual operation to verify your idea

The density of aluminum profile is only 2.7g/cm3, which is about 1 / 3 of that of steel, copper or brass (7.83g/cm3 and 8.93g/cm3 respectively). Aluminum exhibits excellent corrosion resistance in most environmental conditions, including in air, water (or brine), petrochemical and many chemical systems.

conductivity

Aluminum profile is often used because of its excellent conductivity. On the basis of equal weight, the conductivity of aluminum is nearly twice that of copper.

Thermal conductivity

The thermal conductivity of aluminum alloy is about 50-60% of that of copper, which is beneficial to the manufacture of heat exchangers, evaporators, heating appliances, cooking utensils, as well as the cylinder head and radiator of automobiles.

Non ferromagnetism

Aluminum profile is non ferromagnetic, which is an important characteristic for electrical industry and electronic industry. Aluminum profiles are not self ignitable, which is important for applications involving handling or contacting flammable and explosive materials.

Machinability

The machinability of aluminum profile is excellent. In all kinds of wrought and cast aluminum alloys, as well as in all kinds of states of these alloys, the machining characteristics change greatly, which requires special machine tools or technology.

Formability

Specific tensile strength, yield strength, ductility and corresponding work hardening rate control the variation of allowable deformation.

Oil leakage in CNC machining

The oil change does not meet the requirements.

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

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

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

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

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

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

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

(4) It is forbidden to touch tools and chips of CNC milling machine by hand. The chip must be cleaned with a brush.

The cutting problem of computer gong processing

1、 Exit angle (draft angle)

All plastic molds should have a mold angle, otherwise they will be scratched. If it is not indicated in the drawing, you can discuss with the mold maker. The mold angle is generally 0.5 ~ 3 degrees. If the mold is etched, the mold angle should be larger, 2 ~ 5 degrees, depending on the thickness of the etched pattern.

2、 Cutting problem

Most of the time, when the cutter is just milled, the amount of cutting is relatively large, which is easy to cause the cutter to break and bounce. At this time, you can first roughen the lower cutter position, or lift the cutter away, or lower the cutter outside the material in the daytime. In a word, this problem should be fully considered. Grab the knife, spring the knife, drop the knife, when the processing capacity is relatively large, the knife clip is too long, the knife is too small, this often happens. When the processing capacity is relatively large, especially when the concentration feed is large, it is easy to occur. For example, when the depth of the smooth side is 50 mm and the diameter is 3 / 4, we can process it in 25 mm twice, so it is not easy to occur. Tool clamping is too long, the length of the tool is very important for processing, should try to clamp short, beginners are easy to ignore this problem, the program paper must indicate the length of the tool clamping. It’s easy to grab the knife when turning the corner. The solution is to use a smaller knife to clear the corner layer by layer, and then change the larger knife to smooth the side.

3、 Sharpen a knife

The shapes of computer gongs are different, so we often need to grind all kinds of knives. When all kinds of molding knives are worn out, we also need to grind them. Only when we reach the following points can we grind a usable knife.

The four corners of the tool should be the same height.
A is higher than D.
The forward (tool face) of the tool is higher than the back, that is, it has a certain back angle.

4、 Milling direction

The reason is that the rigidity of the computer gong is relatively good, it is not easy to let the cutter, the back clearance is small, and the milling shape or inner groove is left compensation. When machining left and right symmetrical shapes, the profile tool path cannot be mirrored, otherwise the processing effect of the mirrored side is not good. In order to communicate with the operator of the machine tool, the program paper should include:

Program name
Tool size and length
Method of machining tool path
Machining allowance
Rough or light knife
Drawing file name

Precision CNC machining

When the precision of precision machining is nanometer or even atomic unit (the atomic lattice distance is 0.1-0.2 nanometer), the cutting method can not adapt to it. It needs the help of special machining method, that is, the application of chemical energy, electrochemical energy, thermal energy or electric energy, to make these energies exceed the bonding energy between atoms, so as to remove the adhesion, bonding or bonding between some atoms on the workpiece surface In order to achieve the goal of ultra precision machining. 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 methods is that the amount of material removed or added to the surface layer can be controlled very finely. However, to obtain ultra precision machining accuracy, it still depends on precision machining equipment and precise control system, and uses ultra precision mask as 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.

What are the characteristics and functions of the system? It is an automatic machine tool controlled by program. The control system can logically process the program with control code or other symbol instructions, decode it by computer, so that the machine tool can execute the specified action, and the blank can be processed into semi-finished parts by cutting tools.

The traditional mechanical lathe processing is manual operation, ordinary machine operation, lathe processing with hand shaking mechanical tool cutting metal, rely on the eyes with calipers and other tools to measure the accuracy of the product. Modern industry has long used computer-controlled machine tools for operation, which can automatically process any product and parts according to the program compiled by technicians in advance.

The information is stored in the information carrier (such as disk, perforated tape, magnetic tape, etc.) and then read in by the CNC system on the machine tool (or directly input through the keyboard of the CNC system, or input through the communication mode). By decoding the information, the lathe can process the action and parts, and the modern CNC machine tool can be widely used It is a typical product of mechatronics and the technical foundation of new generation production technology and computer integrated manufacturing system.

The development trend of modern CNC lathe precision machining is high speed, high precision, high reliability, multi-function, compound, intelligent and open structure. The main development trend is to develop intelligent full-function universal numerical control device with open structure in both software and hardware. Numerical control technology is the basis of machining automation and the core technology of numerical control machine tools. Its level is related to the national strategic position and the level of reflecting the national comprehensive strength. It develops with the development of information technology, microelectronics technology, automation technology and detection technology. CNC machining is a kind of numerical control machine tool with tool magazine, which can automatically change the tool and process the workpiece in a certain range.

Independent performance of CNC machining

There is a certain difference between the two ways to make precision hardware processing parts. What’s more, they use different steel to make different workpieces. CNC lathe is composed of bed, headstock, turret feed system, cooling and lubrication system and CNC system. Different from ordinary lathe, CNC lathe feed system is qualitatively different from ordinary lathe

It does not have the traditional tool box, slide box and change gear frame, but directly uses servo motor or stepper motor to drive slide and tool through ball screw to realize feed movement. The CNC system consists of CNC unit, input and output module and operation panel.

Processing method of precision hardware parts:

Solid solution strengthening: because the solute atoms enter into the gap or node of the solvent lattice, the lattice will be distorted and the hardness and strength of the solid solution will be increased. This phenomenon is called solid solution strengthening.
Compound: a new crystal solid structure with metallic properties is formed by the combination of alloy components. Mechanical mixture: an alloy consisting of two crystal structures. Although it has two kinds of crystals, it is a component with independent mechanical properties.
Ferrite: interstitial solid solution of carbon in a-Fe (body centered cubic iron).
Austenite: interstitial solid solution of carbon in g-fe
Cementite: stable compound (Fe3C) formed by carbon and iron.
Pearlite: a mechanical mixture of ferrite and cementite (F + Fe3C contains 0.8% carbon)
Ledeburite: a mechanical mixture of cementite and austenite (containing 4.3% carbon) Metal heat treatment is one of the important processes in mechanical manufacturing. Compared with other processes, heat treatment generally does not change the shape and overall chemical composition of the workpiece, but endows or improves the performance of the workpiece by changing the microstructure inside the workpiece or the chemical composition on the surface of the workpiece.

Computer gong processing and clamping

Roughening: under the maximum load of the machine tool, in most cases of processing, select the largest possible tool, the largest possible feed amount and the fastest possible feed. In the case of the same tool, the feed is inversely proportional to the feed amount. In general, the load of the machine tool is not a problem. The principle of tool selection mainly depends on whether the two-dimensional angle and three-dimensional arc of the product are too small The principle is that the length of the tool is greater than the depth of processing. For large workpieces, it is necessary to consider whether the collet can be lowered. Otherwise, it is necessary to go as follows. 0 I4 Q6 x1 f5 l N& u

The purpose of light knife: to meet the workpiece processing requirements: finish, flying die allowance, copper male spark position, etc., at the same time, as large as possible, as fast as possible, because the precision knife takes a long time, with the most appropriate feed and feed, in the same feed, the larger the transverse feed, the faster. The surface feed is related to the finish after processing, and the feed size is related to the surface shape In the case of no damage to the surface, the minimum allowance should be left, the maximum knife should be used, the fastest Belt should be rotated, and the proper feeding should be carried out.

Clamping method:

All clamps are long horizontally and short vertically;
Vise clamping: the clamping height should not be less than 10 mm. When processing the workpiece, the clamping height and processing height must be specified. The processing height should be about 5 mm higher than the vise plane, so as to ensure the firmness and not damage the vise. This kind of clamping belongs to general clamping, and the clamping height is also related to the size of the workpiece. The larger the workpiece is, the higher the clamping height will be;
Splint clamping: the splint is fixed on the worktable with the code, and the workpiece is locked on the splint with the screw. This kind of clamping is suitable for the workpiece with insufficient clamping height and large processing force, generally medium and large workpieces, and the effect is very good. 1 ` Q( F9 k, n
When the workpiece is large, the clamping height is not enough, and it is not allowed to lock the thread at the bottom, it should be clamped with code iron. This kind of clamping needs secondary clamping. The procedure is as follows: A. code the four corners first, process other parts, then code the four sides, and process the four corners. The principle is that during the secondary clamping, be very careful not to let the workpiece loose, code first and then loosen. B. code both sides first, process the other two sides, 8 L # y% @# \: e’ N% P

Code iron has an advantage, large contact area, not easy to deformation, such as aluminum, magnesium within the soft metal must use code iron to prevent deformation;

Tool clamping: diameter more than 10 mm, not less than 30 mm; diameter less than 10 mm, not less than 20 mm,

Note: the impact of the tool on the workpiece can cause: a. the workpiece moves; B. the tool is broken; C. the tool is deformed and the workpiece is damaged; D. the tool is loose, the tool is dropped or the workpiece is not processed correctly

Therefore, the clamping of tool and workpiece should be firm. Strictly prevent Tool Collision and direct insertion of workpiece, & H #: X # {3 W

Classification of cutting tools and their application scope:% Q + e’c. B-Z

By material:

White steel knife: easy to wear, used for roughening of copper and small steel

Tungsten steel knife: used for angle cleaning (especially steel material) and light knife. . g4 k+ L1 U0 h/ s3 P+ T

Alloy knife: similar to tungsten steel knife

Purple knife; used for high speed cutting, not easy to wear

According to the cutter head:, ~. A “{2 s; t

Flat bottom knife: used for plane and straight body side cleaning (plane angle / m3 Z / M)_ , Z

Ball cutter: used for all kinds of surface medium light, light knife) F + I-m: B0 F8 G-V) H

Ox nose knife (one side, two sides and five sides): used for roughening steel (r0.8, r0.3, r0.5, r0.4) – X / F9 x, H: v

Rough leather knife: used to cut rough, pay attention to the remaining method (0.3)

According to the arbor: straight knife: straight knife is suitable for all kinds of occasions 9 a # x E + x0 a% E

Slant bar cutter: but not suitable for straight face and face with inclination less than the inclination of bar (S2 [7 d & D% O6 M0~

According to the blade: two blade, three blade, four blade, the more blades, the better the effect, but the more work, speed and feed corresponding adjustment, more blades, long life, ball knife and flying knife light knife difference: {: Q & i7 U3 | 0e

Ball knife: when concave ruler is smaller than ball ruler and plane ruler is smaller than ball R, the light can not reach (clear the bottom angle).

Computer gong processing method

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 adjusting 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 normal operation of the machine tool and accessories. CNC computer gong NC machining is the basis of modern manufacturing technology, the invention of electricity for the manufacturing industry, has epoch-making significance and far-reaching influence. When clamping the workpiece, according to the way of clamping and placing in the programming operation instruction, it should be considered to avoid the processing parts and the situation that the cutter head may encounter the fixture in the processing.

After the workpiece is placed on the pad iron, it is necessary to pull the table for the workpiece datum according to the drawing requirements. For the workpiece that has been ground on six sides, it is necessary to check whether its verticality is qualified.

The nut must be tightened after the work-piece is pulled to prevent the work-piece from shifting during the processing due to the loose clamping; pull the work-piece again to ensure that the error does not exceed the tolerance after the clamping.

3、 Number of workpieces touched

For the clamped workpiece, the contact head can be used to set the processing reference zero position. The contact head can be used in photoelectric type and mechanical type. There are two kinds of methods: middle collision number and unilateral collision number

Photoelectric static, mechanical speed 450 ~ 600rpm. Manually move the x-axis of the worktable according to the collision number to make the collision number head touch one side of the workpiece. When the collision number head just touches the workpiece and the red light is on, set the relative coordinate value of this point to zero. Then manually move the x-axis of the worktable to make the collision number head touch the other side of the workpiece. When the collision number head just touches the workpiece, record the relative coordinate at this time.

According to the relative value minus the diameter of the collision head (i.e. the length of the workpiece), check whether the length of the workpiece meets the requirements of the drawing.

Computer gong processing vertical processing

The height of the vertical machining center is limited, which reduces the processing range of the workpiece, which is the disadvantage of the vertical machining center. However, the workpiece clamping and positioning is convenient for vertical machining center; the cutting path is easy to observe and debug, the program inspection and measurement is convenient, the problems can be found in time, and the treatment or modification can be stopped; the cooling conditions are easy to establish, and the cutting fluid can directly reach the surface of the cutting tool and processing; the three-axis and Cartesian coordinate system, intuitive feeling, in line with the design point of view, the chip is easy to exclude and modify, Surface treatment to avoid scratches. Compared with the corresponding horizontal machining center, it has the advantages of simple structure, small floor area and low price.

Mainly used for:

Using grease and oil circulation in machining center will produce abnormal heating.
Spindle, need high-definition washing, high-speed bearing sealing place

working principle:

The use of compressed air flow pipe, transmission oil along the pipe caused by continuous flow, stirring and transportation of oil and gas processing center spindle part and other parts of the screw need lubrication. The constant pressure dry compressed air (bar) 5 – 8 continuous supply, according to the spindle and lubricating oil lubrication, screw oil and other parts of the fuel consumption different quantitative supply. Therefore, each lubrication circuit must use a separate micro pump power supply of oil. After the oil pump, it must enter the oil and natural gas mixing valve. In the oil and natural gas mixing valve, the compressed air flow blows into small oil drops and adheres to the wall to form an oil film. The flow direction of the air flow between the oil film and the pipe wall, and the thickness of the medium oil film gradually becomes thinner, but not together.

Maximum depth allowed for each cutting, actual m auxiliary function, s speed, t tool change, R radius, u, W are relative G: preparation command M: auxiliary command T: tool s: spindle speed, R: arc radius, and then p q R, where R means different.

Structure of computer gong machine

Casting, which is the most important part of the computer gong, directly affects the accuracy, stability, wear resistance of the computer gong and the service life of the machine tool. After the casting is finished, Dongguan computer gong processing is not immediately used in production. The good casting is that after wind and rain, sun exposure, natural weathering, some of them are soaked in sea water, and then processed until the casting does not change. The machine tool made in this way is not easy to change, and can maintain the stability and accuracy of the machine tool for a long time.
Spindle, the spindle is used to directly face the workpiece, it is driven by the motor to work, high-speed rotation, the spindle is equipped with a tool handle, it can chip the workpiece, meet various production needs, the quality of the spindle will directly affect the processing accuracy, if the internal bearing is worn, it is easy to cause the swing of the spindle, the accuracy of the processed things naturally has a few deviations . At present, the rotation speed of the main shaft is generally about 8000 rpm, and the high-speed machine can achieve more than 20000 rpm, and each machine has only one main shaft.
The screw rod is also a part of the fuselage. The machining of mechanical parts is driven by the servo motor. The displacement of the worktable is driven by the copper sleeve of the screw rod to meet the machining needs. If there is a gap in the screw rod, it is also directly reflected in the machining accuracy and finish.
There are two kinds of motors: servo motor and frequency conversion motor. The servo motor has good stability, high power of spindle drive motor and low coordination rate of three-axis drive motor.
The coupling is installed between the screw rod and the motor, which is just a linkage function.
The lubrication cooling system consists of an automatic oil pump, a spindle oil cooler and a chip liquid circulation system. The machine oil can be automatically fed and automatically pumped without manual operation

Elements of cutting conditions

For high efficiency metal cutting, the processed materials, cutting tools and cutting conditions are the three major elements. It determines the processing time, tool life and processing quality. The economic and effective machining method must be reasonable selection of cutting conditions.

The three elements of cutting conditions: cutting speed, feed and cutting depth directly cause tool damage. With the increase of cutting speed, the temperature of tool tip will rise, which will produce mechanical, chemical and thermal wear. If the cutting speed is increased by 20%, the tool life will be reduced by 1 / 2.

The relationship between the feed condition and the tool wear is very small. But when the feed rate is large, the cutting temperature rises, and the back wear is large. It has less influence on the tool than the cutting speed. Although the influence of cutting depth on the tool is not as big as cutting speed and feed rate, the hardened layer of the material to be cut will also affect the life of the tool.

Reasonable selection of cutting tools

① In rough turning, the cutting tools with high strength and good durability should be selected, so as to meet the requirements of large back feed and large feed.

② When finishing turning, the cutting tools with high precision and good durability should be selected to meet the requirements of machining accuracy.

③ In order to reduce the tool changing time and facilitate tool setting, the machine clamping tool and machine clamping blade should be used as far as possible.

Reasonable selection of fixture

① Try to use general fixture to clamp workpiece, avoid using special fixture;

② In order to reduce the positioning error, the positioning datum of parts coincides.

Determine the processing route, which refers to the movement path and direction of the cutter relative to the part in the process of NC machine tool processing.

① It should be able to meet the requirements of machining accuracy and surface roughness;

② The processing route should be shortened as far as possible to reduce the tool idle travel time.