Machinery industry – Page 11 – CNC Machining & Turning, Milling, Metal parts

Chip removal of computer gongs

It is said that the chip forming device with positive rake angle on the blade can reduce the cutting force and reduce the cutting power consumption by 15% – 25%. It can also guide the chip to leave the cutting area, so as to prevent the side of the machined part from being scratched by the chip. The chip is guided to flow inward (tool center) rather than outward (workpiece sidewall). The tool is equipped with two types of blades, one is used for slotting and the other is for cutting.

Tanglot milling cutter can be supplied as FDN flange type or SDN disc type cutter. The tool width can be adjusted according to the tool collet used and the blades with different widths. The range of tool diameter is 100-250mm, and the width of tool is 6.0-14.6mm. The new tool can be used for grooving and cutting of automobile bearing cover, steering knuckle and connecting rod, as well as other conventional slotting.

(2) Seco tools Inc. claims its new crown MF5 chip breaker has increased tool life by 67% in field cutting tests and improved chip control in 41% of tests. According to the company, MF5 chip breaker is optimized for semi finish machining related to near net machining. Its chip breaking groove can generate very small cutting force and allow the tool to carry out advanced cutting at a cutting depth of 0.5-2.7mm. MF5 chip breaker adopts crown shape with three sharp forks, chip guiding platform and cooling channel, which is conducive to small deep cutting and ultra-high pressure cooling. In addition, the open geometry angle can reduce the cutting force. The chip breaker has a ground island shaped protuberance, which can improve the positioning of the blade and is conducive to the heat dissipation of the workpiece and cutting edge.

MF5 chip breaker is used in 8 kinds of positive C-type and standard W-type blades (brand numbers are TK1000, tk2000, tp1000, tp3000 and duratomic tp2500). When roughing the steel rock bit (hardness hrc42 ～ 45), the tool life of TK1000 made of MF5 chip breaker is 5 times longer than that of a competitive chip breaker. In the similar cutting experiment with MF5 tp2500 blade, compared with tp2000 blade with M5 chip breaker, the productivity is increased by 55% and the tool life is increased by 360%.

(3) Sandvik Coromant’s new LC blade geometry prevents chip clogging that often occurs when cutting difficult to machine materials. Because of the edge shape design of LC blade, the risk of chip accumulation in machining low carbon steel workpiece is reduced, so the tool life and machining surface finish are improved. The scraping edge can increase the feed rate. The company provides LC turning blade grades for low carbon steel machining, including gc4225, gc1525 and gc2025.

(4) It is designed by guhring-48, Inc., which is easy to produce fine cutting chips. The 3365 series allows slotting and rough milling of steel parts at high cutting speeds and feed rates, while achieving maximum metal removal with minimum torque horsepower, the company said. The milling cutter is also suitable for machining titanium and titanium alloy aviation materials and nickel base alloy.

Cobalt collar has also launched 3376 series aluitech LR and 3364 series roughtech Alu three groove carbide end mills for processing aluminum and aluminum alloys. The above three kinds of end milling cutter series are supplied according to the standard specifications, and the cutter diameter ranges from 6.0 mm to 20.0 mm.

Mainly engaged in a variety of plastic mold design, manufacturing and plastic products injection, injection, pad printing and other processing services. The company produces a wide range of mold types, including various household appliances, computer weekly products, communication products, power tools and CD, DVD, MP3, MP4 categories, etc., which can be used to make rapid template mold and two-color molding mold. It can take into account large, medium and small die. The largest mold size is 2 m * 1 m, and the maximum weight can reach 8 tons.

Honing of parts processing

Honing is a machining method that uses a group of diamond (or cubic boron nitride) honing heads with different diameters according to the size order, and each grinding head only makes one reciprocating cutting action in turn. After all the honing heads are machined, the final part requirements are met. The sequential honing technology is developed on the basis of traditional honing, which combines honing method with reaming method, so it is also called honing; in addition, sequential honing generally only has one reciprocating action, so it is also called single stroke honing

The characteristics of sequential honing mainly lie in its sequential honing head and actual honing process. Compared with the traditional honing process, the honing head of sequential honing has been set to the final machining size required by the workpiece in advance. Therefore, the cutting process of sequential honing only needs 1-3 reciprocating strokes. The thickness of metal layer removed by each honing head is 2-20 μ M. The shape and dimension accuracy of the hole can be improved by one level after the sequential honing, and the surface roughness value can reach Ra0.2. This processing method does not need tool feed, the processing time is fast, and also can improve the position accuracy of the hole to a certain extent.

Compared with ordinary honing machine, sequential honing machine has some advantages in processing beat, dimensional stability, shape and position accuracy. However, the domestic users of this honing machine tool used to rely entirely on imports. Because of the high price of machine tools, machine accessories and after-sales service, many users are deterred from importing sequential honing machines. The users who have the ability to purchase imported sequential honing machines also affect their production due to the lack of timely technical support from imported machine tools. Until the beginning of 2008, the third machine tool branch of Beijing No. Compared with foreign manufacturers which have developed for many years, they started later, but started higher. The sequential honing machine tools produced by them have been favored by many users as soon as they come into being, and have achieved multiple sales.

The machine tools they produce adopt German Siemens Servo motor and 810D numerical control system to realize the flexible adjustment of reciprocating speed and position, realize the real-time detection of processing torque of each processing shaft and set overload alarm; adopt German fibro rotary table, which has accurate positioning and fast speed, and the transposition time of each station reaches 0.69s; the rolling guide rail and ball screw of Japan THK can realize this At present, the spindle box is stable and accurate reciprocating; the honing tool, tool extension rod and workpiece fixture are all of full floating structure, which can ensure high honing accuracy: roundness: 0.001 mm, cylindricity: 0.002 mm, roughness: Ra0.2 μ m; processing beat is 9s / piece. Their machine tool also adopts modular design, and the number of spindles and turntable stations can provide users with the best processing scheme according to the process requirements of users and their parts. In recent years, with the batch launch of domestic medium-sized CNC machine tools, some high-end CNC machine tools began to enter the core manufacturing field of key industries, and were initially applied.

At the high-level forum of CNC machine tool exhibition, the equipment utilization rate of similar imported machine tools was 89.5%, and the domestic equipment was basically close to the same level of foreign equipment. “

As the user side of domestic CNC machine tools, the main problems of domestic CNC machine tools are the lack of design and innovation ability, slow response speed, no serial and high maturity CNC system, the quality of accessories needs to be improved, and the overall service awareness is weak.

According to the special plan for high-end CNC machine tools and basic manufacturing equipment, by 2020, about 80% of the high-end CNC machine tools and basic manufacturing equipment required by aerospace, shipbuilding, automobile and power generation equipment manufacturing will be based in China, which requires the industry to focus on the automobile, machinery manufacturing, military and other key downstream industries.

Experts suggest that the machine tool industry in the “Twelfth Five Year Plan” period should develop high-end market segments, focus on the product and process requirements of high-end customers and major customers, and provide personalized services according to the needs of customers. At the same time, we should closely track the development of strategic emerging industries and provide them with advanced and applicable machine tools and equipment.

Methods of quality inspection

Seven new methods of QC

① Relation graph method (association graph method);

② KJ method (affinity graph method, card method);

③ System diagram method (tree diagram method);

④ Matrix diagram method;

⑤ Matrix data analysis method;

⑥ Process decision program chart (PDPC)

Or major accident prediction chart method;

⑦ Network graph method (also known as network planning technology < PERT > method or vector diagram is also called critical path

Line method)

Five core manuals of ISO / TS16949

① FMEA (potential failure mode and effect analysis)

mode and effects Analysis）；

② MSA (measurement system analysis);

③ SPC (statistical process control);

④ APQP (advanced product quality planning and control plan)

Product Quality Planning (APQP) and Control Plan)；

⑤ PPAP (production part approval process)

The most important of the five manuals is APQP

10s / five constant method

（1） 10s from 5S

1s: finishing (Seiri)

2S: Seiton

3S: cleaning (seis0),

4S: cleaning (seiketsi)

5S: accomplishment (shitsijke)

6S: Safety

7S: saving / speed

8s: Service (servlce)

9s: satisficatl0n

10s: persistence

Five regular methods

The five constant method is a technology used to maintain the quality environment, which is called 5S in western countries. Hong Kong is known as the “five constant laws”. Due to the language needs, it has translated five English words, namely, structure, systematise, sanitise, standardization and self discipline. The implementation of the five standing laws in Hong Kong naturally requires the cooperation of five Chinese characters. It is also what we usually say: sorting out, rectifying, cleaning, and self-cultivation.

Chinese * English (5-s) * 50 points * court example*

① Often organize structurise 10 to throw away or return unnecessary items

② The file can be found in 30 seconds after regular systematise rectification

③ 5 people should be aware of hygiene responsibility

④ Storage transparency of standard 15;

⑤ Self discipline 10 daily use of five

Dry, semi dry and low temperature cold air cutting technology

In the process of cutting, elastic deformation, plastic deformation and friction deformation occur in the three deformation zones, 99.5% of the cutting power is transformed into shear slip deformation (the first deformation zone), the friction deformation of the rake face (the second deformation zone), and the energy consumed by extrusion, excess deformation and friction deformation of the back face (the third deformation zone), and it is transformed into heat energy in an instant, resulting in the temperature rise of chip, cutting edge area and workpiece surface.

Cutting heat is an inevitable physical phenomenon in the process of metal cutting, which has a significant impact on the quality of workpiece and tool life. In low-speed cutting, mechanical wear is the main reason for tool wear; while in high-speed cutting, high-temperature induced tool wear changes from mechanical wear to diffusion wear, phase change wear and carbonization wear, and leads to adhesive wear on the tool surface. Cutting heat also causes the thermal expansion of cutting tools and workpieces, aggravates the friction and wear of the flank of the cutting tool, and causes the surface roughness of the workpiece to rise. Therefore, the ultra precision machining process emphasizes that the conduction of cutting heat in the workpiece and tool must be controlled timely and effectively. It is also very important to control the temperature rise of tool and workpiece for NC machining.

The cutting heat of metal originates from the strength, hardness, toughness, plasticity and elasticity of materials. The research also shows that the temperature rise of cutting tool and workpiece is closely related to the contact area, heat transfer coefficient, temperature difference, contact time and so on. Generally speaking, reducing the cutting rate can reduce the contact area between the tool and the heat source; increasing the flow rate and flow rate of the cooling medium is to increase the heat transfer coefficient; reducing the temperature of the cooling medium can increase the heat capacity and temperature difference effect of the cutting tool and workpiece; and increasing the machine speed and cutting speed actually shortens the heat conduction time of cutting.

It can be seen that in order to control the cutting heat of metal and the temperature rise of cutting tools and workpieces, various factors must be considered comprehensively. In addition to the reasonable selection of cutting tools and cutting process parameters according to the characteristics of metal materials and machining technical indicators, the most direct measure is to use various cooling media to quickly take away the cutting heat on the tool and workpiece and reduce the temperature.

Advanced rapid tooling manufacturing technology

With the rapid development of laser rapid prototyping (RPM), China has reached the international level and gradually realized commercialization. The commercial rapid prototyping processes in the world mainly include SLA (stereolithography), LOM (layered and separated manufacturing), SLS (selective laser sintering) and 3d-p (three-dimensional printing).

Tsinghua University first introduced sla250 (stereolithography or photosensitive resin laser curing) equipment and technology from 3D company of the United States and carried out research and development. After several years of efforts, it improved and launched the “m-rpms type multi-functional rapid prototyping manufacturing system” (with layered solid manufacturing SSM and melt extrusion molding MEM), which is the only world with independent intellectual property rights in China The system of rapid prototyping process (national patent) has good performance price ratio.

Die less multi-point forming technology is another advanced manufacturing technology that uses the height adjustable punch group to replace the traditional die for sheet metal surface forming. The die less multi-point forming system takes CAD / CAM / CAT technology as the main means to realize the automatic forming of three-dimensional surface rapidly and economically. Jilin University of technology has undertaken the national key scientific and technological research projects related to dieless forming, and has independently designed and manufactured die-free multi-point forming equipment with international leading level.

Compared with MIT, Tokyo University and Tokyo University of technology in the United States, China’s technology is in a leading position in theoretical research and practical application, and is now developing in terms of popularization and application.

The resin stamping die has been successfully applied in the trial production of domestic car for the first time. The main features of the former and the second models of the former and the second type of the former and later parts of the car were manufactured by the former and the latter, respectively The gap between punch and die is accurately controlled by imported special wax. The dimension precision of the die is high. The manufacturing cycle can be shortened by half to two thirds, and the manufacturing cost can be saved about 10 million yuan (12 sets of dies). It opens up a new way for trial production and small batch production of cars in China. The experts of Ciba fine chemicals in Switzerland believe that it can reach the international level in the 1990s.
On site inspection technology of mould

With the development of precision mould, the requirement of measurement is higher and higher. For a long time, the precise CMM is limited by the environment and seldom used in the production site. The new generation CMM has the characteristics of temperature compensation, anti vibration material, improving dust-proof measures, improving environmental adaptability and reliability, so that it can be easily installed in the workshop and used in order to realize the field measurement.

Laser surface quenching repair of mould

The main purpose of die surface treatment is to improve the surface hardness, wear resistance and corrosion resistance. The application of laser surface strengthening technology has greatly improved the surface performance of mold. For the key parts of the mold, the conventional heat treatment is manual flame quenching. Flame quenching has many limitations, such as low hardness, easy deformation and cracking, which needs further processing and correction. The laser quenching can not only solve the above problems, but also can improve the wear resistance and service life of the same hardness, and local quenching can be carried out for the difficult parts.

For improving the service life of large-scale dies and reducing the heat treatment deformation of precision dies, laser surface strengthening technology has great technical advantages, mainly including laser surface quenching and laser surface cladding.

laser surface hardening

Laser surface hardening is a kind of technology that uses high energy laser beam to scan the workpiece to harden the scanned area.

The characteristics of laser quenching

(1) Laser quenching is rapid heating and self-excited cooling, without furnace heat preservation and coolant quenching. It is a pollution-free green heat treatment process, which can easily implement uniform quenching of large mold surface.

(2) Because the laser heating speed is fast, the heat affected zone is small, and the surface scanning heating quenching, namely instantaneous local heating quenching, the deformation of the treated die is very small.

(3) Because the divergence angle of the laser beam is very small and has good directivity, the mold surface can be accurately quenched by the light guide system.

(4) The hardened layer depth of laser surface quenching is generally 0.3 ~ 1.5mm.

Diamond grinding and polishing of mould

In order to avoid scratches and burns to the surface of the workpiece, special care must be taken when polishing with ා 1200 and ා 1500 sandpaper. Therefore, it is necessary to load a light load and use two-step polishing method to polish the surface. When each type of sandpaper is used for polishing, it should be polished twice along two different directions, with each rotation of 45 ° to 90 ° between the two directions.

Diamond grinding and polishing should pay attention to the following points:

(1) This kind of polishing must be carried out under light pressure as far as possible, especially when polishing pre hardened steel parts and polishing with fine grinding paste. When polishing with ා 8000 grinding paste, the common load is 100 ~ 200g / cm2, but it is difficult to maintain the accuracy of this load. To make this easier, make a thin, narrow handle on the wood, such as adding a piece of copper, or cut a part of the bamboo strip to make it softer. This helps to control the polishing pressure to ensure that the die surface pressure is not too high.

(2) When using diamond grinding and polishing, not only the working surface is required to be clean, but also the worker’s hands must be carefully cleaned.

(3) Each polishing time should not be too long, the shorter the time, the better the effect. If the polishing process is too long, it will cause “orange peel” and “pitting”.

(4) In order to obtain high quality polishing effect, polishing methods and tools which are easy to heat should be avoided. For example: polishing wheel polishing, the heat generated by polishing wheel can easily cause “orange peel”.

(5) When the polishing process stops, it is important to ensure that the surface of the workpiece is clean and that all abrasives and lubricants are carefully removed, and then a layer of mold antirust coating shall be sprayed on the surface.

At present, mechanical polishing is still the main factor affecting the quality of mold polishing. In addition, it is also related to mold material, surface condition before polishing and heat treatment process. High quality steel is the prerequisite to obtain good polishing quality. If the surface hardness of steel is uneven or there are differences in characteristics, polishing difficulty will often occur. All kinds of inclusions and pores in the steel are not conducive to polishing.

3.1 the influence of different hardness on the polishing process increases the difficulty of grinding, but the roughness decreases after polishing. Due to the increase of hardness, the polishing time required to achieve lower roughness increases correspondingly. At the same time, the possibility of over polishing decreases with the increase of hardness.

Centerless cylindrical grinder

The grinding machine which uses centerless grinding method to grind the rotating surface of workpiece is usually referred to as centerless cylindrical grinder. In centerless cylindrical grinder, the workpiece is not centered and supported by the center, but placed between the grinding wheel and the guide wheel, supported by the supporting plate and guide wheel. Generally, the grinding wheel is installed at the end of the spindle, and the grinding wheel with width greater than 250 mm is installed in the middle of the spindle, and the maximum width of the grinding wheel can reach 900 mm. The grinding wheel rotates at a high speed, and the guide wheel rotates in the same direction at a slow speed to drive the workpiece to rotate for circular feed.

In the process of through grinding, the axial feed is realized by adjusting the small inclined angle of the guide wheel axis, which is suitable for grinding slender cylindrical workpiece, short shaft without central hole and sleeve type workpiece. In cut in grinding, radial feed is realized by the movement of guide wheel frame or grinding wheel carrier. It is suitable for grinding workpieces with shoulder or boss, as well as workpieces with cone, sphere or other lines being curved. The productivity of centerless grinder is high, and it is easy to realize automation after various loading and unloading devices. Most of them are used in mass production and can be operated by unskilled workers. The grinding accuracy of centerless grinder is generally 2 μ m in roundness and 4 μ m in size. High precision centerless grinder can reach 0.5 μ m and 2 μ m respectively. In addition, there are centerless internal grinder and centerless thread grinder.

The centerless grinder can repair and compensate automatically. The guide wheel feed guide rail is double V-shaped needle roller guide wheel, which is fed by servo motor and can compensate each other with grinding wheel dressing. The machine tool is equipped with automatic loading and unloading mechanism, which can carry out automatic cycle grinding.

Geometric modeling of parts

(1) Geometric modeling of parts

For NC programming of complex shape parts based on drawings and measurement data of feature points, the first step is to establish the geometric model of the parts to be processed.

(2) Reasonable selection of processing scheme and processing parameters

The efficiency and quality of NC machining depend on the reasonable selection of processing scheme and parameters. The optimal selection of tool, cutter axis control mode, tool path and feed speed is the premise to meet the processing requirements, normal operation of machine tool and tool life.

(3) Tool path generation

Tool path generation is the most important content in NC machining of complex shape parts. The possibility, quality and efficiency of machining are directly determined by the generation of effective tool path. The primary goal of tool path generation is to make the generated tool path meet the requirements of no interference, no collision, smooth path, smooth cutting load and high code quality. At the same time, the tool path generation should also meet the conditions of good universality, good stability, high programming efficiency and small code amount.

(4) NC machining simulation

Due to the complexity of the shape of the parts and the complexity of the machining environment, it is very difficult to ensure that the generated processing program does not have any problems, among which the most important are the over cutting and undercutting in the machining process, the interference and collision between various parts of the machine tool, etc. For high speed machining, these problems are often fatal. Therefore, it is necessary to take some measures to check and correct the processing program before actual processing. Numerical control machining simulation tests and optimizes the processing program by simulating the processing environment, tool path and material removal process by software. It has the characteristics of good flexibility, low cost, high efficiency and safety and reliability, and is an important measure to improve the efficiency and quality of programming.

(5) Post processing

Post processing is an important part of NC machining programming technology. It transforms the tool position data generated by general pre-processing into NC machining program suitable for specific machine tool data. Its technical contents include kinematic modeling and solution of machine tool, compensation of machine tool structure error, check and correction of non-linear error of machine tool motion, stability check and correction of machine tool motion, feed rate check and code conversion, etc. Therefore, post-processing plays an important role in ensuring the machining quality, efficiency and reliable operation of the machine tool.

Machining performance of CNC and RP

In the past, great progress has been made in prototyping. At first, most RP technologies have obvious advantages in terms of speed, but their further development is limited due to the problems of accuracy and material properties. Since the advent of RP, due to the threat of some competition, CNC can improve its speed and bring well-known benefits. Similarly, RP has been improved in accuracy, material properties and surface polishing. Understanding these two technologies is particularly important for selecting the right machining tool for the job. The following guidance can help in the selection of tools.

Material Science

RP restricted

The research of materials has gone through a long process. The range of material selection is enlarged, and the performance is guaranteed. At present, the available materials are metal, plastic, ceramic and composite materials, and the selection of materials is still limited. Moreover, the properties of most of the materials are not well matched with those of processing, molding and pouring.

CNC machining is almost unlimited

The machining center can cut almost all materials.

The maximum size of the part, the maximum size of RP is 600x900x500mm

Although the existing industrial equipment can not process dashboard or baffle, the existing prototype can be used to produce most of the daily necessities and industrial products. If the parts to be produced by the equipment are too large, the components can be produced first and then combined into a complete part. It must be noted that size has an effect on time and it takes longer to make larger parts.

CNC machining can produce aircraft parts

CNC machining can produce the actual size of parts and modules, from small desktop devices to large bridge equipment. It can be said that the limitation of CNC size only comes from the mechanical tools used.

Complexity of parts

RP unlimited

If a sample can be molded with design software, the time or cost of manufacturing is hardly affected. Rapid and cheap production of complex parts is one of the greatest advantages of RP