The weight and size range of cast aluminum parts are very wide. The lightest weight is only a few grams, the heaviest can reach 400 tons, the thinnest wall thickness is only 0.5 mm, the thickest can exceed 1 meter, and the length can be several millimeters to ten. A few meters can meet the requirements of different industrial sectors. Generally, for the appearance quality of aluminum castings, comparison samples can be used to judge the surface roughness of lost wax aluminum casting, and the fine cracks on the surface can be inspected by the coloring method and the magnetic powder method. The internal quality of aluminum castings can be inspected and judged by audio, ultrasonic, eddy current, X-ray and γ-ray methods.

The quality of aluminum castings has a great influence on the performance of mechanical products. For example, the size, accuracy and surface roughness of the impellers, casings and hydraulic parts of various pumps directly affect the working efficiency of pumps and hydraulic systems, energy consumption and the development of cavitation, etc. Internal combustion engine cylinders, The strength and shock resistance of aluminum castings such as cylinder heads, cylinder liners, piston rings, exhaust pipes, etc. directly affect the working life of the engine.

The principle of casting aluminum casting method selection: aluminum casting is preferred to sand casting. The main reason is that sand casting has lower cost than other casting methods, simple production process, and short production cycle. When the wet type cannot meet the requirements, consider using clay sand surface dry sand type, dry sand type or other sand types. The casting method of aluminum castings should be compatible with the production batch. Low pressure casting, die casting, centrifugal casting and other casting methods are only suitable for mass production because of the expensive equipment and molds. Aluminum castings can be cast in single pieces or mass production.

Shrinkage porosity of cast aluminum generally occurs in thick parts at the root of the fly riser near the inner runner, the wall thickness transition part and the thin wall part with a large plane. The fracture is gray in the as-cast state, and the light yellow is grayish white, light yellow or gray black after heat treatment.

Cleaning method of aluminum casting:

1. Casting shell cleaning: Generally speaking, aluminum castings can be further cleaned up after they are completely cooled. After the aluminum castings are cast in the shell, the cooling time of the castings in the mold is related to the material and lost wax aluminum casting. The shape and size of the parts are directly related to the production conditions. Generally, if the cleaning of aluminum alloy castings is done early, it will easily cause deformation and cracks of the aluminum castings. The cooling time of castings with larger size and more complicated process should be longer, and the cooling time of castings with smaller size and thin wall and simple process can be shorter.
2. Cutting pouring riser: The main methods of cutting pouring riser are: gas cutting, grinding wheel cutting, sawing machine, hydraulic cutting, anode cutting, etc.
3. Surface cleaning of aluminum castings: After the shelling of aluminum castings, there will always be iron oxide scale remaining on the surface of the castings, especially the castings with complex cavities, deep grooves, and blind holes, which cannot be cleaned completely, and surface cleaning must be performed .
4. Shot blasting treatment: If castings with special requirements can be shot blasting, shot blasting is to use the centrifugal force generated by the high-speed rotating shot blasting impeller to throw iron shots on the surface of the castings to make the surface of the cast aluminum Sand, sticky sand or iron oxide scale is removed. Generally speaking, the surface of the casting after shot blasting is related to the size of the iron shot.
5. Repair welding: usually refers to castings that do not meet the acceptance technical conditions or the requirements of the order agreement, and have casting defects but can be repaired. First of all, we must clean up the repair welding parts, so that the surface of the aluminum casting is completely clean and exposed to the metallic luster. The size of the defects should be welded from small to large. For example, the area of repair welding is large and the defects should be annealed after welding in important parts of the casting.

Aluminum castings have low cost, good manufacturability, remelting and regeneration to save resources and energy, so the application and development of this material are enduring. Such as research and development of cupola-electric furnace double smelting technology and equipment; extensive use of advanced molten iron desulfurization and filtration technology; thin-wall high-strength iron casting manufacturing technology; cast iron composite material manufacturing technology; iron casting surface or local strengthening technology; isothermal Yanghuo nodular cast iron complete set of technology; using metal mold casting, metal mold sand-coated casting, continuous casting and other special processes and equipment. Because of its low density, high specific strength, and corrosion resistance, cast lost wax aluminum casting light alloys will be more widely used in aviation, aerospace, automobile, machinery and other industries. Especially in the automobile industry, in order to reduce fuel consumption and improve energy utilization, it is a long-term development trend to replace steel and iron castings with aluminum and nickel alloy castings.

Among them, it focuses on solving pollution-free, high-efficiency, easy-to-operate refining technology, metamorphism technology, grain refinement technology and rapid detection technology before the furnace.

In order to further improve the material performance and maximize the potential of the material, high-quality aluminum alloy materials, especially aluminum-based composite materials, can be developed to meet the performance requirements of different working conditions; strengthen the research on the cluster alloy melting process, and continue the alloy die casting and squeeze casting Process and related technology development research; perfect ferroalloy smelting equipment and related technology and process development research.

Characteristics of cast aluminum parts:
1. Durability
Aluminum has strong stability and oxidation resistance, aluminum alloy castings will not rust and corrosion;
The surface adopts electrostatic powder spraying and fluorocarbon paint, and the various large-scale indoor and outdoor decorative products manufactured can keep the color for a long time.
2. Plasticity
Aluminum has good ductility and is convenient for various shapes and designs.
It has toughness, can be used repeatedly, and has a wider range of applications.
3. Security
After various rigorous tests, the aluminum products’ resistance to earthquakes, wind pressure and weathering are guaranteed.
The unique aluminum alloy casting method makes the work weight lighter, reduces the burden in the handling and construction operations, and reduces the risk.

Repetitive production parts processed by CNC lathes: The preparation time of procedures using CNC grinders occupies a relatively high proportion. For example, process analysis preparation, programming, adjustment and trial cutting of the first part of the part, the total of these comprehensive man-hours is often dozens to hundreds of times the man-hours of a single part titanium machining, but the work content of these CNC lathes can be saved and used repeatedly, so When a part is successfully trial-produced on a CNC grinder and then repeatedly put into production, the production cycle is greatly reduced, the cost is less, and better economic benefits can be obtained.

It is required to focus on ensuring the quality of the key parts in small and medium batches that can be produced efficiently: CNC grinding machines can achieve high-precision, high-quality, and high-efficiency grinding machining under computer control. Compared with special grinding machines, it can save a lot of special process equipment, has strong flexible manufacturing capacity and obtain better economic benefits. Compared with ordinary grinders, it can eliminate many man-made interference factors in the long process flow of complex machining, and the accuracy of machining parts is good, the interchangeability is good, and the machining efficiency is high.

The parts processed by the CNC lathe should meet the technological characteristics of the multi-process centralized titanium machining of the CNC grinder. When the CNC grinder processes the parts, the grinding wheel cuts the workpiece and the corresponding non-nc grinder is exactly the same, but it can perform some machining accuracy requirements For example, in terms of grinding range, ordinary grinders are mainly used to grind cylindrical surfaces, circular CNC lathe cones or the end faces of stepped shoulders. In addition, CNC cylindrical grinders can also grind circles. Torus, as well as the above complex combined surfaces in various forms.

The machining batch of parts should be larger than that of ordinary lathes and batches. When machining small and medium batches of parts on non-CNC grinding machines, the pure cutting time only accounts for 10%-30% of the actual working hours due to various reasons. When machining on a multi-process centralized CNC grinding machine such as a grinding machining center, this ratio may rise to 70% to 80%, but the man-hours for preparing adjustments are often much longer, so the parts batch will become too small. uneconomic.

Considerations for the titanium machining of some special parts processed by CNC lathes. Although some parts are processed in small batches, ordinary lathes have complex shapes, high quality and good interchangeability. This cannot meet the above requirements on non-CNC grinders and can only be arranged. Machining on CNC grinders, such as parabola, cycloid cams and special-shaped mirrors.

In the machining process of the CNC machining center, whether the selection of the positioning reference is reasonable determines the quality of the parts, and has a great influence on whether the dimensional accuracy and mutual position accuracy of the parts can be guaranteed and the machining sequence arrangement between the parts. When the workpiece is installed with a fixture, the choice of positioning datum will also affect the complexity of the fixture structure. This requires the fixture not only to withstand greater cutting force, but also to meet the requirements of positioning accuracy. Therefore, the choice of positioning reference is a very important technical issue. So how to choose a positioning datum when machining parts with a CNC machining center? Here is a brief introduction:

1. The selected datum should ensure the accurate positioning of the workpiece, facilitate the loading and unloading of the workpiece, quickly complete the positioning and clamping of the workpiece, the clamping is reliable, and the fixture structure is simple.

2. The CNC machining center has simple operations between the selected datum and each size of each processed part, which can minimize the calculation of the dimensional chain and avoid or reduce the calculation links and calculation errors.

3. Ensure machining accuracy. When determining the part positioning datum, the following principles should be followed:

1) The origin of the workpiece coordinate system, that is, the “program zero point”, does not have to coincide with the part positioning datum, but there must be a certain geometric relationship between them. The choice of the origin of the workpiece coordinate system is mainly for the convenience of programming and measurement. For parts with high dimensional accuracy requirements, when determining the positioning datum, it should be considered whether the positioning datum can accurately measure the coordinate origin of the CNC machining center.

2) When machining benchmarks and finishing at each station of the CNC machining center, the selection of positioning benchmarks should consider as much machining content as possible for finishing. For this reason, it is necessary to consider a convenient positioning method for each surface to be processed. For example, for the box, it is best to use the positioning method of two pins on one side, so that the tool can process other surfaces.

3) Try to choose the design datum on the part as the positioning datum. This requires that when roughing, consider what kind of roughing datum to use to machine each surface of the finishing datum, that is, each positioning datum used by the CNC machining center must be processed on the previous ordinary machine tool or other machine tool. In this way, it is easy to ensure the accuracy relationship between the machining surfaces of each station.

4) When the positioning datum of the CNC machining center parts is difficult to coincide with the design datum, the assembly drawing should be carefully analyzed to determine the design function of the part design datum, and through the calculation of the dimensional chain, strictly specify the shape and position between the positioning datum and the design datum Tolerance range to ensure machining accuracy.

5) When the station machining including the design datum cannot be completed at the same time in the CNC machining center, try to make the positioning datum coincide with the design datum. At the same time, it should be considered that after positioning with this datum, all key precision parts can be processed by one clamping.

There are two types of cutting fluids used in CNC machining in Dongguan: one is oil-based cutting fluid and the other is water-based cutting fluid;

The cutting fluid used in cnc machining is divided into four types: cutting oil, emulsion, semi-synthetic fluid, and synthetic fluid; for the above four cnc machining cutting fluids,

You may commonly use cutting oil, emulsion (called soapy water in some places), synthetic fluid (many people call it environmentally friendly fluid), and you may know less about semi-synthetic nights;

How do you choose cutting fluid during machining? Let’s take a look at the advantages and disadvantages of each cutting fluid:

1. Cutting oil for CNC machining in Dongguan:

advantage:

  • a. Very high physical lubrication
  • b. Suitable for low speed, less cutting allowance
  • c. Provide very good surface finish
  • Disadvantages:
  • a. Poor heat transfer
  • b. Fire hazards
  • c. High usage cost
  • d. Smoke/fog

2. Emulsion used in Dongguan CNC machining:

advantage:

Better lubrication

  • a. Safe for multiple metals
  • b. It has better cooling compared with cutting oil
  • c. Better scouring ability of iron filings
  • d. Lower cost than cutting oil
  • e. Better anti-rust
  • f. Easy to treat sewage

Disadvantages:

  • a. Increase in dosage
  • b. Emulsify dirty oil
  • c. Poor odor control
  • d. Dirty equipment
  • e. Poor stability against hard water
  • f. Poor filtering
  • g. Poor mixing

3. Semi-synthetic fluid used in Dongguan CNC machining:

advantage;

  • a. Better cooling than emulsion
  • b. Better anti-rust
  • c. Use cleaner than emulsion
  • d. Better filterability
  • e. More suitable for hard water and dirty oil
  • f. More suitable for hard water and dirty oil
  • g. It has better antibacterial properties than emulsion

Disadvantages:

  • a. There is a tendency to foam in soft water
  • b. Oil repellency is worse than synthetic fluid
  • c. When used in high concentrations, there may be skin allergies
  • 4. Synthetic fluid used in Dongguan CNC machining:

advantage:

  • a. Very good cleanliness
  • b. Will not smell
  • c. High operator acceptance
  • d. Low consumption turnover rate (12-20 weeks)
  • e. Very good cooling
  • f. Repellent oil completely
  • g. Low foam
  • h. Long service life
  • i. Very good filtration/fast settling performance

Disadvantages:

  • a. Low physical lubrication
  • b. Difficulty in sewage treatment
  • c. Sticky residue, especially in hard water
  • d. Not compatible with emulsion
  • e. React with some polycarbonate
  • f. Paint that may damage the machine tool

The machining center is a highly mechatronics product. It has a variety of technologies and comprehensive machining capabilities. It performs multiple cutting functions based on the use of a cutting machine. It also belongs to a compound machine tool and a CNC machine tool with more functions.

Of course, the system of a titanium machining center is not only a numerical control system, but also many other very important systems to assist machining, such as servo systems, lubrication systems, and cooling systems. The function of each system is different, except for the mechanical mechanism of the whole machine, it can only rely on these systems to form a complete cycle.

Commissioning of machining center:

1. Add oil to each lubrication point according to the requirements of the manual, fill the hydraulic oil tank with the required hydraulic oil, and connect the air source.

2. Power on, each component is powered on separately or each component is powered on after a power-on test. Investigate whether each component has an alarm, manually investigate whether each component is normal, whether each safety device is working, so that all links of the machine tool can be operated and Get in motion.

3. Grouting. After initial operation, roughly adjust the precision of the machine tool, and adjust the titanium machining relative orientation of the main moving parts and the host after disassembly. Align the manipulator, tool magazine, communication workbench, position, etc. After these tasks are completed, the anchor bolts of the main engine and various accessories can be filled with quick-drying cement, and the reserved holes for the anchor bolts in various places can be filled flat.

4. Debugging. Prepare various inspection tools, such as fine level, standard square ruler, parallel square tube, etc.

5. Fine-tune the level of the machine tool to make the accuracy within the range of the error allowed. Using multi-point pad support, adjust the bed to a level in a comfortable state to ensure the stability of the bed after adjustment.

6. Use manual operation to adjust the position of the manipulator relative to the spindle, and use an adjustment mandrel. When installing a large-weight tool holder, it is necessary to carry out active communication between the tool magazine and the spindle position repeatedly to ensure accuracy and no impact.

7. Move the worktable to the communication position, adjust the relative position of the pallet station and the exchange workbench, to achieve the active communication action of the workbench is stable, and the workbench is installed with a large load for titanium machining repeated communication.

8. Check whether the setting parameters of the CNC system and the programmable manipulator PLC device match the specified data in the random data, and then test the main operating functions, safety measures, and the execution of common instructions.

CNC machining center is the abbreviation of computer network digital economy control machine tool, which is an automatic machine tool controlled by a program. Use the digital information of the enterprise to manage and control the movement of the machine tool and the machining and production process. General cnc machining machine tools refer to precision engineering machinery product machining, cnc machining lathes, milling machines, boring machines, etc. How to reasonably set the center, speed and feed of CNC machining?

CNC machining can use control codes or other symbolic instructions to logically process programs. Use the computer to translate it into code, so that the machine can run according to the prescribed actions. Through turning, milling cutter and other tools, the blank is processed into semi-finished or finished parts. Currently, CNC machining machine tools have been widely used in various machining platforms. CNC machining centers have become the development trend and necessary technical means of mold machining.

During the use of CNC machining, some process parameters need to be set, such as feed rate, spindle speed, spindle forward and reverse, tool change, coolant switch, etc.

The spindle speed, feed speed and cutting rate of the CNC machining center are mainly determined by the tool. The parameters of the machining tool for different quantities of the same material are different. However, the tool will provide parameters to be set at the time of purchase. For example, three Gatwick import tools, where the tools will provide different materials and machining parameters such as feed rate, cutting and speed.

The development of cutting motion speed can be calculated according to the relevant formula, cutting speed = (machining a diameter/3.14/rotation speed) * 1000. For example, if you want to machine holes with different diameters of 50mm, the actual cutting speed of the tool is 150m/min.
Spindle speed = (150 / 3.14 / 50) * 1000 = 955 revolutions
Make reasonable settings according to the size of the tool, the hardness of the machining technology material, the performance of the machine tool, and the precision of mold production and machining. The tool is large, the material is hard, and the accuracy can be low, the speed is slow, and vice versa. Specific problems should be explored based on work and life experience.

The characteristic of the machining center is one-sided: when a one-sided to the clamp is used for machining, the CNC controls the machine tool and automatically changes the tool according to different selected steps; automatically changes the spindle speed, feed speed and tool comparison with the workpiece. Function, continuous drilling trajectory, countersinking, reaming, drilling, tapping, milling and other machining procedures, used to automatically process each surface of the workpiece. Because the machining center can be shared and automatically implement various machining operations to avoid human error, reduce the time of workpiece clamping, workpiece and adjustment work machine and measurement, machining and storage time, greatly improving the machining efficiency and so Has good economic benefits. The space can be divided into vertical machining centers and horizontal machining centers according to the position of the spindle machining center.

CNC machining is also called CNC machining. Cutting is common in CNC machining equipment. CNC machining is high-efficiency machining, which is controlled by a post-programmed computer. Therefore, CNC machining has stable machining quality, high precision and high repeatability. In the actual process, human factors and operating experience will greatly affect the machining quality. CNC machining center wants to operate the machine efficiently, these details must not be overlooked.

  • In general, the arrangement of the machining time sequence should be considered according to the structure of the part and the status of the blank, as well as the needs of market positioning, and the focus is that the rigidity of the workpiece is not damaged by the environment. Sequential development should generally be carried out according to the following principles:
    One: The numerical control machining of the procedure cannot affect the positioning and clamping of the next procedure, and the general machining procedure should be considered comprehensively.
    2: Process the inner cavity, and then process the outer shape.
    Three: Positioning is the same, clamping or machining the same tool CNC connection to reduce repeated positioning, the number of tool changes and the same steps of moving the platen.
    Four: For the multiple machining procedures carried out in the same installation, the procedures should be arranged with little damage to the rigid structure of the workpiece.
    Which aspects should be paid attention to when determining workpiece clamping?
    The following three points should be paid attention to when determining the target positioning system reference and clamping plan:
    1. Strive to have the same benchmarks for design, craftsmanship and programming.
    2. Minimize the number of fixtures, as far as possible, all curved surfaces processed by CNC can be processed in one positioning.
    3. Avoid using manual payment adjustment scheme.
    4. The fixture should be opened smoothly, and the development of its positioning and clamping mechanism cannot directly affect the cutting in cnc machining (such as cultural collision). When encountering some such problems, use a vise or add a bottom plate to pull the screw Way of clamping.

CNC lathe machining has been more and more used in modern manufacturing, and it has exerted its incomparable advantages over ordinary lathes. CNC lathe machining has the following characteristics:
1. The transmission chain of CNC lathe machining is short. Compared with ordinary lathes, the main shaft drive is no longer the speed of the motor belt gear mechanism, but the horizontal and longitudinal feeds are driven by two servo motors respectively, and no change is used. The transmission chain is greatly shortened by traditional parts such as, clutch.
2. High rigidity. In order to match the high precision of the numerical control system, CNC numerical control lathes have high rigidity in order to meet the high precision advance cnc machining requirements.
3. Lightly drag, the tool post (workbench) is moved by ball screw pair, with low friction and light movement. The supporting special bearings at both ends of the screw have a larger pressure angle than ordinary bearings and are selected when leaving the factory. The lubrication part of CNC lathe machining is automatically lubricated with oil mist. These measures make the CNC CNC lathe machining mobile easy.

  • Two, CNC numerical control lathe machining characteristics
    1. A high degree of automation can reduce the operator’s physical labor intensity. The CNC lathe machining process is automatically completed according to the input program. The operator only needs to start tool setting, load and unload the workpiece, and change the tool. During the machining process, the main task is to observe and supervise the operation of the lathe. However, due to the high technical content of CNC lathes, the operator’s mental work is correspondingly improved.
    2. CNC CNC lathe machining parts have high precision and stable quality. The positioning accuracy and repeat positioning accuracy of CNC lathes are very high, and it is easier to ensure the consistency of a batch of parts. As long as the process design and procedures are correct and reasonable, coupled with careful operation, the parts can be guaranteed to obtain high machining accuracy and easy to align. The CNC lathe machining process implements quality control.
    3. CNC numerical control lathe machining and production efficiency are high. CNC lathe machining is able to process multiple machining surfaces in clamping again, generally only the first part is tested, so it can save many intermediate processes in ordinary lathe machining, such as scribing, size inspection, etc., reducing auxiliary time. Moreover, because the quality of the parts processed by the CNC lathe is stable, it brings convenience to the subsequent process, and its overall efficiency is significantly improved.
    4. CNC lathe machining is convenient for new product development and modification. CNC lathe machining generally does not require a lot of complicated process equipment, and parts with complex shapes and high precision requirements can be processed by programming the machining program. When the product is remodeled or the design is changed, only the program is changed, without the need to redesign Tooling. Therefore, CNC numerical control lathe machining can greatly shorten the product development cycle, and provide a shortcut for the research and development of new products, product improvement, and modification.
    5. CNC lathe machining can be developed to a more advanced manufacturing system. CNC lathe machining and its machining technology are the basis of computer-aided manufacturing.
    6. The initial investment of CNC lathe machining is relatively large. This is due to the high cost of CNC lathe machining equipment, long preparation period for the first advance cnc machining, and high maintenance costs.
    7. CNC CNC lathe machining and maintenance requirements are high. CNC lathe is a typical CNC lathe machining product of technology-intensive mechatronics. It requires maintenance personnel to understand both mechanical and microelectronic maintenance knowledge, and at the same time, it must be equipped with better maintenance equipment.
  • Three,Parts suitable for CNC lathe machining
    1. CNC lathe machining is most suitable for small and medium batch parts of various varieties. With the gradual decline in the manufacturing cost of CNC lathes, the situation of machining large quantities of parts has emerged, whether it is domestic or foreign. When machining small batches and single-piece production, it is also possible to shorten the debugging time of the program and the preparation time of the tooling.
    2. CNC CNC lathe machining parts with high precision requirements. The CNC lathe has good rigidity, high manufacturing accuracy, accurate tool setting, and convenient size compensation, so it can process parts with high dimensional accuracy.
    3. CNC numerical control lathe processes parts with small surface roughness values. When the material of the workpiece and the tool, the finishing allowance and the tool angle are certain, the surface roughness depends on the cutting speed and feed rate. Ordinary lathes have a constant speed, and the cutting speeds are different for different diameters. For example, CNC lathes have a constant linear speed cutting function. The same linear speed can be used when turning the end face and the outer circle of different diameters to ensure that the surface roughness value is small and consistent. When machining surfaces with different surface roughness, choose a small feed rate for a surface with a small roughness, and choose a larger feed rate for a surface with a large roughness. The variability is very good, which is difficult to achieve on ordinary lathes.
    4. Parts with complex contour shapes. Any plane curve can be approximated by a straight line or a circular arc. CNC CNC lathe machining has circular interpolation function, which can process a variety of complex contour parts.
  • Fourth, the management and use of CNC lathe machining
    The use of CNC lathe machining requires the careful use of the operator, and must rely on scientific management. A perfect management system and scientific production mode are effective means to improve production efficiency.
    1. Establish a sound and complete management system to effectively control and supervise the work of the relevant personnel of the CNC lathe, so that the operation and operation of the lathe can be controlled.
    2. Strengthen the training of technicians and skilled worker management personnel. The training of CNC machining is always a long-term work and a process of continuous improvement. Through training craftsmen, they can compile more simplified CNC machining processes, simplify procedures, and shorten machining time; technical workers can improve operating skills; managers can better understand the characteristics of CNC equipment, process control, and implement management with modern production management concepts.
    3. Scientifically organize production. Improve the problem of work stoppage and unbalanced production capacity, increase the operating rate of CNC lathe machining, rationally arrange production beats, and rationally allocate production tasks. Use the similarity of parts advance cnc machining to classify the parts to be processed, so as to make reasonable arrangements in process preparation, production planning and scheduling, and improve the balance of equipment production capacity. Scientific production batches will greatly reduce the ratio of lathe adjustment time and tooling preparation time, which can improve batch efficiency.
    4. In order to give play to the value of CNC lathe machining, the operator must correctly master the principles of CNC lathe operation. Operate the lathe correctly according to the lathe operating procedures; process the parts according to the process and program requirements; coordinate the dimensions of the parts, tools, and pressure plates before machining on the CNC lathe to avoid interference and collision; improve technical quality, reduce non-machining time such as tool installation and alignment; correct Maintain various auxiliary tools to ensure reliable accuracy.
  • Fives,Conclusion
    The application of CNC lathe machining has become increasingly widespread, and how to “manage, use, and maintain” CNC lathes has become an important issue to be solved urgently. The use of CNC lathe machining is not a simple use of equipment, but a series of applications with strong attributes. Only by scientific management, fully understanding the characteristics of CNC lathe machining, and coordinating the balance of various production links, can it truly bring out its economic benefits.

Matters needing attention in CNC machining process design

1CNC machining should be rough first and then refined

The so-called roughing first and then finishing principle mainly refers to first increase the machining speed by roughing, and then increase the effective use of the margin by means of finishing. Specifically, rough titanium machining should be carried out in advance before finishing to further reduce the machining allowance and the number of moving tools, which fundamentally promotes the greatly improved work efficiency. After the roughing is completed, the finishing should be carried out after a period of time. The reason is that the related parts after roughing will have slight deformation to different degrees. After a period of recovery, the parts will be restored to the original state to the maximum extent. Since the uniformity of the margin after roughing can not be effectively used in the whole process of finishing, semi-finishing is generally implemented to ensure the full use of the margin. In short, in the work of machining parts, the relevant staff should strictly adhere to the principle of roughing and finishing to effectively ensure the accuracy and smoothness of the product.

2 CNC machining should be positioned once

If CNC machining staff want to promote the continuous improvement of production efficiency, they should make the parts complete as many procedures as possible under the same conditions, and achieve the concentration of procedures to reduce the appearance of errors. Precise positioning can ensure that the surface position of the workpiece is more specific. In this case, the staff should organically combine multiple processes and then use a unified standard for positioning. Therefore, the actual staff of CNC machining must use it as a reference level to scientifically arrange the beginning and end of the process, so as to lay a good foundation for the development of the process and speed up the titanium machining speed. In addition, CNC machining designers should also formulate reasonable standards in advance and make unified arrangements.

3CNC machining should be close first and then far

The principle of proximity can play a very crucial role in CNC machining. Normally, the position relatively close to the tool point should be processed first, while the far position needs post-machining, which greatly reduces the actual distance of the tool movement. It can be seen that the machining position and the distance from the tool position are very important. From the perspective of milling and turning, the principle of near first and farther away can effectively improve cutting conditions and help increase product rigidity. In short, CNC machining should adhere to the principle of proximity and the principle of machining the inner surface first in the selection of design options to continuously improve machining efficiency.

4CNC machining other matters needing attention

In the entire process of CNC machining, the relevant staff should also strictly follow the relevant principle of least calling of tools, least procedures and least calling of accessories, etc. Based on the strict implementation of the above principles, production efficiency can be greatly improved. However, there are still many special circumstances during the entire production period. When special circumstances occur, these principles are often inappropriate to apply. The actual titanium machining personnel must be required to proceed from the actual situation to rationalize the problem. For example: In the process of assembling parts, it is difficult to complete all parts machining at one time due to the loss of parts. In this case, continuous improvement should be made in the subsequent steps. In addition, the design plan should also adhere to the counterproductive principle, requiring the machine tool staff to work out a scientific treatment plan based on the actual situation and must not stick to the rules.

In order to meet the requirements of the main transmission of CNC lathe machining, CNC machine tools (attribute: automated machine tools) often use a motor stepless speed regulation system. In order to expand the speed adjustment range and meet the requirements of low speed and large torque, gear stepped speed regulation and motor control The method of combining multi-level speed regulation realizes spindle speed regulation. In the numerical control machining, the control system issues instructions to make the tool perform various movements that meet the requirements, and the shape and size of the workpiece are expressed in numbers and letters in the form of technical requirements and machining requirements. It generally refers to the process of machining parts on CNC manufacturing machine tools. In order to improve production automation, shorten programming time and reduce CNC machining costs, a series of advanced CNC machining technologies have been developed and used in the aerospace industry.

  • 1. Mechanical gear shift
    In the main transmission system of CNC lathe machining, the traditional spindle box structure is greatly simplified due to the stepless speed regulation of the motor. However, due to the limitation of the spindle motor and the driving power supply, the output of constant torque is often in its low speed range. In order to possibly enable the spindle to provide the maximum output power of the main motor in the entire speed range and meet the needs of CNC machine tools (attributes: automated machine tools) for low-speed and powerful cutting, 1 to 4 gears and stepless speed regulation are often used The combined method is the so-called stepless speed regulation. The use of mechanical gear reduction not only amplifies the output power, but also expands the speed range.
    When CNC lathe machining is cutting, the spindle runs automatically at the speed specified by the S command in the part machining program (procedure). Therefore, there must be two types of spindle speed command signals in the numerical control system, that is, analog (definition: virtual for real things or processes) or digital signals (S code (code)) to control the drive adjustment of the spindle motor. Speed circuit, while using switch signal (M code) to control the actuator (organization) of mechanical gear speed automatic shift. The automatic shift actuator is an electric-mechanical conversion device, commonly used hydraulic shift fork and electromagnetic clutch (Clutch).
  • 2. Motor speed regulation
    The speed-regulating motors used for the spindle drive of CNC lathes are mainly divided into two categories: DC and AC.
    (1) DC motor speed regulation-usually CNC manufacturing machine tools have a large speed regulation range, and the DC motor speed regulation adopts both voltage regulation and magnetic regulation. The characteristic curve of its typical DC spindle motor is shown in Figure 61. From its characteristic curve, it can be seen that the motor below the speed n0 belongs to constant torque speed regulation, that is, it is realized by changing the armature voltage; above the speed n0, it belongs to the constant power (referring to the work done by the object in unit time). How much) speed regulation is achieved by changing the excitation current (Electron flow).
    The more commonly used FANUC DC-excited spindle motor adopts a three-phase fully controlled thyristor (zhá) tube non-circulating current reversible speed regulation system, which can realize voltage and magnetic speed regulation, and the speed range is 35 ?~3500r/min. CNC machining General CNC machining usually refers to computer digital control precision machining, CNC machining lathe, CNC machining milling machine, CNC machining boring and milling machine, etc. The feed route of finishing is basically carried out along the part contour sequence. Therefore, the focus of determining the feed route is to determine the feed route of rough machining and idle stroke.
    (2) AC motor speed regulation
    At present, cage induction motors are used in AC spindle drives of CNC machine tools, and vector control (control) frequency conversion (frequency conversion) speed regulation methods are widely used.
    With the improvement of new DC and AC spindle speed control motors, motor speed control will be widely used, but in economical CNC machine tools (attributes: automated machine tools) in order to reduce the cost, mechanical gear shifting is often used Method to change the spindle speed. In the numerical control machining, the control system issues instructions to make the tool perform various movements that meet the requirements, and the shape and size of the workpiece are expressed in numbers and letters in the form of technical requirements and machining requirements. It generally refers to the process of machining parts on CNC manufacturing machine tools. In order to improve production automation, shorten programming time and reduce CNC machining costs, a series of advanced CNC machining technologies have been developed and used in the aerospace industry.

There are many methods for surface machining of inner holes of CNC lathes. Commonly used are drilling, reaming, reaming, boring, turning, grinding, drawing, grinding, honing, and rolling holes.

  • Applicable method for inner hole machining of CNC lathe machined parts:
    Reaming: Reaming is to use a reaming drill to further process the drilled hole to enlarge the aperture and improve the accuracy (precision) and reduce the surface roughness value. The dimensional tolerance level that can be achieved by reaming is IT11~IT10, and the surface roughness value is Ra12.5~6.3μm. It belongs to the semi-finishing method of hole machining. It is often used as pre-machining before reaming, and can also be used as precision (precision) The final machining of holes that are not high.
    1. Drilling: Drilling holes in the solid part of the workpiece with a drill. CNC machining is a process method for parts machining on CNC machine tools. The process regulations of CNC machine tool machining and traditional machine tool machining are generally consistent, but significant changes have also taken place. A machining method that uses digital information to control the displacement of parts and tools. It is an effective way to solve the problems of variable parts, small batches, complex shapes, and high precision, and to realize high-efficiency and automatic machining. The drilling is rough machining, and the dimensional tolerance grade can reach IT13~IT11, and the surface roughness value is Ra50~12.5μm. Is it due to the long length of the twist drill, the small core diameter and poor rigidity, and the influence of the chisel edge.
    2. Reaming: Reaming is a finishing method for holes on the basis of semi-finishing (reaming or semi-finishing boring). In the numerical control machining, the control system issues instructions to make the tool perform various movements that meet the requirements, and the shape and size of the workpiece are expressed in numbers and letters in the form of technical requirements and machining requirements. It generally refers to the process of machining parts on CNC machine tools. In order to improve production automation, shorten programming time and reduce CNC machining costs, a series of advanced CNC machining technologies have been developed and used in the aerospace industry. The size tolerance of the reaming hole can reach IT9~IT6, and the surface roughness value can be Ra3.2~0.2μm. There are two types of reaming: organic hinge and hand hinge. Reaming on a machine tool is called machine hinge, and reaming by hand is called hand hinge.
    3. Turning hole: The turning hole on the lathe is the rotation of the workpiece and the movement of the turning tool. The aperture can be controlled by the cutting depth of the turning tool and the number of passes, which is more convenient to operate. In the numerical control machining, the control system issues instructions to make the tool perform various movements that meet the requirements, and the shape and size of the workpiece are expressed in numbers and letters in the form of technical requirements and machining requirements. It generally refers to the process of machining parts on CNC machine tools. In order to improve production automation, shorten programming time and reduce CNC machining costs, a series of advanced CNC machining technologies have been developed and used in the aerospace industry. Lathe turning holes are mostly used to process the holes of disc sleeves and small brackets.
    4. Boring: Boring is the further machining of holes that have been drilled, cast or forged with a boring tool. It can be performed on a lathe, boring machine or milling machine. Boring is one of the commonly used hole machining methods, which can be divided into rough boring, semi-fine boring and fine boring. The dimensional tolerance grade of rough boring is IT13~IT12, and the surface roughness value is Ra12.5~6.3μm; the dimensional tolerance grade of semi-finish boring is IT10~IT9, and the surface roughness value is Ra6.3~3.2μm; The dimensional tolerance grade is IT8~IT7, and the surface roughness value is Ra1.6~0.8μm.