Yearly Archive April 28, 2020

Classification and repair of lathe common faults

Because the CNC lathe adopts the computer control skills, the mechanical structure is greatly simplified compared with the common machine tools, and the opportunity for the mechanical system to expose the defects is greatly reduced. The common mechanical defects are mainly as follows: the defects of lathe spindle components. Because of the application of adjustable speed motor, the structure of spindle box of CNC lathe is simple, the disadvantages of which are the tool handle active tension equipment, active speed control equipment, etc.

Disadvantages of ATC. More than 50% of the disadvantages of machining center machine tools with active tool change equipment are related to active tool change equipment, which are mainly revealed in: the disadvantages of tool magazine activity, large missing of positioning difference, unstable clamping handle of manipulator, large error of manipulator activity, etc. When the disadvantages are serious, the tool change is stuck and the lathe is forced to stop working.

It is used to detect the disadvantages of the travel switch voltage in the moving direction of each axis. On CNC machine tools, in order to ensure the reliability of active homework, a lot of travel switches are selected to detect the active position. During the long-term operation of the machine tool, the moving characteristics of the moving parts change. The reliability of the travel switch pressing equipment and the change of the quality characteristics of the travel switch itself have a great impact on the generation and elimination of the defects of the lathe.

Disadvantages of lathe feed drive chain. Because the rolling collision pairs are widely used in the guide rail of CNC machine tools, the main disadvantages of the feed transmission chain are caused by the falling of the active quality, such as the mechanical parts are not moving to the regular position, the operation is stopped, the positioning accuracy is falling, the reverse leisure is increased, the mechanical crawling, the noise of the bearing is increased (usually exposed after the collision), etc., which can be adjusted and maintained from beginning to end Force, adjust the loose link, improve the accuracy of activities and adjust the compensation link.

The method of eliminating the shape error of the spherical surface in CNC machining

When CNC machining spherical surface is more and more quadrant ball and surface, due to improper adjustment, it is very easy to produce shoulder, shovel back and other conditions. The reasons are as follows:

1. System gap formation

In the driving pair of CNC machining equipment, there is a certain gap between the lead screw and the nut. With the increase of the time when the equipment is put into operation, the gap increases gradually due to wear. Therefore, the key factor for the shoulder on the machining surface is to compensate for the corresponding gap during the reverse movement. The clearance measurement usually adopts dial indicator measurement method, and the deviation control is within 0.01-0.02MM. It should be pointed out here that the base and rod should not be extended too long, because the cantilever is long, the base is easy to be moved by force, resulting in inaccurate counting, and the compensation value is not true.

2. Uneven formation of workpiece machining allowance

Before finishing the design surface of CNC machining parts, whether the machining allowance of the surface to be machined is average is also an important reason for forming whether the forming surface can reach the design requirements, because the machining allowance is not uniform, which is easy to form a “reflection” deviation. Therefore, for the parts with high requirements on surface form, before forming, the machining allowance should be as average as possible to reach the design requirements by machining one more profile.

3. Improper tool selection

In the cutting process, CNC cutting tools remove the raw materials through the main cutting edge. However, after the arc passes the quadrant and the arc is tangent to the cutting edge (the intersection of the back edge and the base surface), the cutting may be added to the back edge. Therefore, when choosing or grinding tools, we must study the wedge angle of the tools.

Development and application of precision parts processing technolog

Precision parts processing technology is an advanced manufacturing technology developed to meet the needs of modern high technology, which is the basis of other high-tech practices. It comprehensively uses the new achievements in the development of mechanical technology and modern electronics, sensor technology, optics and computer and other high-tech technologies. It is the basic technology in the high-tech boundary and plays an important role in the modernization of national defense science and technology and the economic construction of the people. At the same time, as the basic technology and an important part of modern high-tech, it promotes semiconductor technology and photoelectric technology , raw material science and other technologies. The machining precision reaches 1 μ m, and the precision parts processing is completed by using precision machine tools, precision measuring tools and meters under strictly controlled environmental conditions.

Precision parts processing

When the machining accuracy reaches or exceeds 0.1 μ m, it is called ultra precision part machining. In aerospace industry, precision parts processing is mainly used to process precision mechanical parts in aircraft control equipment, such as precision mating parts in hydraulic flattening and dynamic servo organization, frame and shell of gyroscope, air flotation, liquid floating bearing components and floats, etc. The structure of aircraft precision parts is complex, the rigidity is small, the precision is very high, and the proportion of difficult to process raw materials is large. The processing efficiency of precision parts is as follows: ① the geometric form and mutual position accuracy of parts reach to micron or angular second level; ② the boundary or characteristic dimension of parts are below micron; ③ the surface micro roughness (surface uniformity height difference) of parts is less than 0.1? Micron; ④ the mutual parts can meet the requirements of coordination; ⑤ Some parts can also meet the requirements of accurate mechanical or other physical characteristics, such as the change of stiffness of torsion bar of float gyroscope, the stiffness coefficient of flexible element, etc.

In recent years, most of the automobile, mold parts and metal processing are made with CNC machine tool as the center, and most of the hole processing is made with advanced equipment such as machining center and CNC machine tool. High-speed and high-precision drilling processing has been put on the agenda. No matter which boundary of precision parts processing, the completion of high-precision and high-speed is an important competitive means to obtain user orders.

Automatic parts show you the function of ultrasonic cleaning

Ultrasonic cleaning is to use the cavitation effect, acceleration effect and direct inflow effect of ultrasonic in the liquid to directly and tactfully affect the liquid and dirt, so that the dirt layer is distributed, emulsified and peeled to reach the cleaning target. At present, more cavitation and direct flow are used in the ultrasonic washing machine.

According to the frequency wave, it can be divided into three types: infrasound wave, acoustic wave and ultrasonic wave. The frequency of infrasound wave is below 20Hz; the frequency of sound wave is 20Hz ~ 20kHz; the frequency of ultrasonic wave is above 20kHz. The infrasound wave and ultrasonic wave in it can’t be heard by ordinary people. Because of the high frequency and short wavelength, the ultrasonic wave has good target and strong penetration, which is the reason of designing and manufacturing the ultrasonic washing machine.

It is one of the methods for protecting teeth and cleaning teeth. In today’s society, a lot of people will do ultrasonic tooth washing.

1. Complete: the key point of ultrasonic tooth washing lies in the subgingival calculus, which is the key cause of periodontitis. Only when the area is clean, can periodontitis be prevented and gum bleeding be improved. This is one of the advantages of ultrasonic tooth washing.

2. Painless: This is also the most important advantage of ultrasonic tooth washing. Adjust the frequency of the head of the cleaning machine according to the amount of calculus of the person who washed the teeth, so as to ensure that the process of tooth washing can be completed in a painless environment.

3. Polishing after operation: it can leave microscopic tiny scratches on the surface of teeth after cleaning. After polishing, it is better to make the teeth more bright and not easy to attach calculus and tooth stains.

4. Safety: all the equipment is sterilized by high temperature and high pressure. The advantages of ultrasonic tooth washing can be used to prevent cross effects.

Discussion on the design of fixture

With the development of machining industry, fixture is more and more valued. It is used in the boundary of machining and becomes an indispensable part of machining. With the development of machine tool technology towards the goal of high speed, high efficiency, meticulous, composite, intelligent and environmental protection, fixture technology is developing towards the goal of high precision, high efficiency, module, combination, general and economic.

Problems in design and research of fixture

Generally, the structure of fixture design is single, which makes people feel that the structure is not very complex. The more we find that the hydraulic fixture is widely used, which greatly simplifies the original mechanical structure. However, if we do not conduct detailed research in the design process, we will inevitably encounter unnecessary difficulties:

1. Blank allowance of machined parts

The size of forming blank is too large, and interference occurs. So we must plan the rough drawing before design. Leave plenty of space

2. Chip removal fluency of fixture

Due to the limited machining space of the machine tool, the fixture is often designed in a compact space. At this time, the iron chips in the machining process are often ignored to accumulate at the dead corner of the fixture.

There are many difficulties in the later processing because of the poor discharge of the liquid containing chips. Therefore, at the beginning of essence, we should study the problems in the process of machining. After all, the fixture will increase efficiency and be easy to operate

3. Overall opening of fixture

Neglecting the opening, making it difficult for the operator to install the card, time-consuming and laborious, and design taboo

4. Basic comment principle of fixture design

Each set of fixture has to go through many times of clamping and loosening behavior, so it may reach the user’s requirements at the beginning, but the fixture should have its accuracy maintenance, so do not design some unreasonable equipment.

Even if you are lucky now, it will not last forever. A good design should be tempered by time.

5. Interchangeability of positioning elements

It is important to wear the positioning elements, so it is necessary to study the quick and simple replacement. It is better not to design large parts

The accumulation of fixture design experience is very important, occasionally design is one thing, and in essence use is another thing, so good design is a process of accumulation and summary.

While studying the problems that should be paid attention to in the design of tooling and fixture, we should adhere to the following basic principles in the design of tooling and fixture

1. Meet the safety and reliability of workpiece positioning in the process of application

2. Sufficient bearing or clamping force to ensure the processing process of workpiece on the fixture

3. Meet the requirements of simple and rapid operation in the clamping process

4. Vulnerable parts must be structures that can be exchanged quickly. When conditions are sufficient, it is better not to use other equipment

5. Meet the reliability of repeated positioning of fixture in the process of adjustment or exchange

6. Try to prevent complex structure and high cost

7. Try to select standard parts as component parts

8. Systematization and standardization of internal products of the company

Because of the importance of fixture, its quality and accuracy directly affect the efficiency of machining, so it is very important to control its quality and accuracy from the source and choose a reliable and capable fixture manufacturer. Shenzhen huayanghua has been focusing on automobile inspection tools, fixture, pallet and three-dimensional processing for 13 years. Our team has cooperated with each other and strictly implemented the customer’s product requirements as our guidelines. We have arranged to complete the product requirements according to the quantity and deliver the products on time.

A great breakthrough in the foundry industry of CNC precision machining machine tools

Thanks to the rising level of forging technology and the cultivation of forging elites, in recent years, China’s CNC carefully processed machine tool forging industry has made a huge breakthrough. Although the market of China’s CNC forging industry has been stagnant and developing slowly in the past year, the output of forging machinery products has been increasing.

Although the development of forging machine tools in China has made positive achievements, its development still faces many restrictive problems. Compared with the overseas forging machine tools, the level of manufacturing technology of forging machine tools in China has obviously fallen, which makes its static operation speed, product accuracy maintenance and reliability of machine tools at the technical level of core operating parts There are obvious shortcomings.

At present, China’s forging machine tool enterprises lack the awareness and strength of self-determination innovation and basic review and discussion, which restricts the development of China’s forging machine tool technology. Only after a profound study of the characteristics and requirements of the product technology of the user industry, and paying attention to the discussion of basic review work, can China’s forging machine tool industry have a better development in the near future.

In addition, compared with the overseas forging machine tools, China’s forging machine tools are obviously lower in the level of manufacturing technology, which makes it have obvious deficiencies in the technical level of core operating parts, static operation speed, product accuracy maintenance and reliability of the machine tools. It can be seen that in the future, the development of domestic forging machine tools in China will start to actively seek new goals and ideas.

In order to meet the development requirements of household structure adjustment and low-carbon economy, and complete the scientific development of forging household products, the following work should be focused on:

1. Cultivate new family property and modern manufacturing service industry, so as to meet the transformation needs of downstream industries, maintain the stable and rapid development of China’s equipment manufacturing industry, and provide the basis for the establishment of modern forging family property system.

2. Build a comprehensive training network system for forging industry. Various modes of running schools really cover up the whole industry.

3. Help enterprises to use international laws such as WTO to deal with trade disputes such as anti marketing and win the right to speak in the international trading system.

4. Adhere to the principle of “go out, please come in”. On the basis of running China’s comprehensive forging industry high level forum and cross strait forging industry high level forum, further run Asia forging industry high level forum and create BRIC forging industry high level forum, and actively join the world forging industry high level forum.

5. Essentially join the international standardization work. In the 12th Five Year Plan period, several draft international forging standards led by China were submitted to the international standardization organization.

6. To carry out the credit rating appraisal of forging industry nationwide.

The decline of forging machine tool technology level is a big bottleneck, which can only be overcome. It is possible for domestic products of forging machine tools in China to break through in essence and develop rapidly in stable development.

The technique of machining thin wall parts with CNC lathe

Because it is difficult to machine the thin wall of CNC lathe, especially the inner hole, because the thin wall is affected by the cutting force in the cutting process, it is easy to produce deformation. This leads to the phenomenon of “waist shape” with small ellipse or middle and big two ends. In addition, due to the poor heat dissipation during the processing of thin-walled casing, it is very easy to produce thermal deformation, making the size and shape and position errors. How to reduce the influence of cutting force on workpiece deformation is an important problem to be solved if it can not meet the drawing requirements.

The machining of thin-walled parts in CNC lathe is a difficult problem in turning, because of the poor rigidity and strength of thin-walled parts, which are easy to deform in machining, increase the form and position error of parts, and not easy to guarantee the machining quality of parts. It can make full use of the characteristics of high machining accuracy and high production efficiency of CNC lathe, and fully consider the influence of process problems on the machining quality of parts. Therefore, it can effectively overcome the deformation in the machining process of thin-walled parts and ensure the machining accuracy by testing the square surface of workpiece clamping, tool geometric parameters, programming, etc, It provides a good basis and reference for better machining thin-walled parts in the future.

No matter what form CNC lathe uses to process parts, first of all, it must start from checking the part drawing. It can be seen from the figure that the thin-walled parts are easy to deform when they are processed. It is not only inconvenient to clamp here, but also difficult to process the parts to be processed. A special thin-walled casing and shaft guard need to be designed.

Analysis of the problem that the CNC lathe can not change the tool

Analysis of the problem that the CNC lathe can not change the cutter 1. The three-phase phase phase of the cutter head motor is reversed or the phase is missing, and the two lines of the cutter head motor are mutually adjusted or checked for external power supply 2. The positive rotation control information Tl + the outgoing terminal of the non transmission multimeter system of the CNC lathe system, measure the + 24V and Tl + contacts, and change the cutter manually together to see if the transmission voltage of these two points is + 24V, If the voltage does not exist, it is a system obstacle, which needs to be sent to the factory for repair or replacement of related IC components.

Analysis of the problem that the CNC lathe can not change the tool

Analysis of the problem that the CNC lathe can not change the tool

The Tl + transmission of forward rotation control information of the system is normal, but there is open circuit in the control information loop or components are damaged. Check whether the forward rotation control information line is open circuit and whether the contact touch of this loop is excellent; Check whether the DC relay or talk touch device is damaged. 4. If the mechanism is stuck, the tool holder will roll by hand. If the tightness level is not stuck, disassemble the tool holder, adjust the mechanism and participate in the smooth liquid.

The machine caused by too long time of anti lock is stuck on the machine to loosen the tool holder, and then the system parameters are adjusted to maintain the tool holder. At the time of anti lock, the tool holder motor of CNC lathe is damaged. Dismantle the tool holder motor and roll it over to see if the motor is rolling. If it is not rolling, and if the circuit is OK, replace the tool holder motor and the tool holder motor with water to form the motor short-circuit drying motor, and add protection Good insulation measures.

No power supply for cutter head motor of CNC lathe check whether the power supply circuit of cutter head motor is open circuit, whether the contact is excellent, and whether the strong electrical components are damaged; Check whether the fuse is fused and the pull-up resistance is not connected. Connect the tool position input information with 2K pull-up resistance. If this resistance is not connected, the tool holder does not turn on the macro level. In essence, the behavior is to turn forward first and then turn immediately, so that the tool holder does not seem to move.

How to control the surface roughness of machined parts

In the machining industry of mechanical parts, the surface roughness of workpieces is also called brightness. Generally, the surface roughness of carefully machined parts is relatively high. In the machining process of mechanical parts, how can we control the surface roughness of machined parts? Let’s share it with everyone!

1. Cutting processing amount: it is suggested to reduce the surface processing amount properly in the cutting feed amount.

2. Select the geometric parameters of the tool: from the geometric parameters of the machining tool, it can appropriately reduce the deflection angle of the pair and increase the radius of the arc of the tool tip, and if necessary, it can grind the polishing edge. It makes the cutting simple and reduces the surface roughness.

3. Control the vibration of machine tool: start from reducing the conflict between the tool and the workpiece, extruding, sharpening the tool edge, adding cutting fluid, and properly heat treating some workpiece materials with good toughness.

4. Choose the right processing technology: in the process of machining the well-rounded mechanical parts, the processing technology process is also very important. If the process flow is not correct, it may affect the processing quality and production efficiency. A lot of carefully processed parts need the requirement of brightness after finishing.

5. Raw material selection difference: mechanical equipment parts are composed of many different raw material processing. According to the raw material density difference, the selection of cutting tools and machine tools in the process of processing is directly related to the surface roughness.

The above is how to control the machining surface roughness of mechanical hardware parts, hoping to help everyone!

How Bad Could It Get? Companies Gauge the Coronavirus Impact

nytimes.com/…/coronavirus-new-york-update

As the coronavirus outbreak spreads, the world’s biggest companies have begun painting a bleak picture of broken supply chains, disrupted manufacturing, empty stores and flagging demand for their wares.

The announcements by businesses like Mastercard, Microsoft, Apple and United Airlines offer a reading on how the virus is affecting consumer behavior and business sentiment. These corporate bulletins — and what executives do in response — could determine how much economic damage the outbreak inflicts and whether a recession looms.

Some companies have expressed optimism that governments will curb new infections and that consumer spending in Europe and North America will be largely unscathed. But if executives see a threat beyond the first three months of the year, they may pare planned investments and even start laying off workers. That, in turn, would further dampen economic activity.

The stock-market plunge this week, the steepest since the financial crisis, suggests that investors are bracing for a lot more bad news.

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“Everything is slowing down even more — and that has not been fully appreciated,” said Michael O’Rourke, chief market strategist at JonesTrading.

The correction in the S&P 500 stock index — a decline of 10 percent or more from a recent peak — was its fastest ever. In the midst of the sell-off, analysts at Goldman Sachs said they expected that the companies making up the S&P 500 would collectively show no profit growth this year. The bank had previously forecast a 6 percent increase in earnings.

A major vulnerability for businesses in the United States and Europe is their increasing reliance on China as a supplier and customer over the last 10 or 20 years.

 
 

 

ImageMicrosoft cut its sales forecast for a division that makes laptops and tablets after the outbreak hampered production.
Credit…Jeenah Moon for The New York Times

Since the Lunar New Year holiday in China a month ago, many workers have been homebound, disrupting factories that assemble electronics or make automotive parts. Microsoft said this week that the virus had hampered production of its laptop and tablet computers, and it cut its sales forecast for the division that makes those products, scrapping a projection it had issued just a few weeks earlier.

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The supply-chain problems have started to affect American homebuilders as well. A senior executive at Toll Brothers said the virus appeared to have delayed the supply of lighting parts.

At the same time, Chinese consumers are buying less. Apple said the closing of stores in China would depress sales of iPhones and other devices.

Mastercard cut its growth forecast in part because people are taking fewer international trips. Fear of the virus has prompted companies like Amazon and Nestlé to suspend international travel by some employees. That drop in demand, combined with their own concerns about the virus, has prompted United and other airlines in the United States and Europe to cancel flights to cities in China and elsewhere in Asia.

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On Friday, United said an investor briefing scheduled next week would be postponed until September. Citing concern over the virus, the airline said it “does not believe it is practical to expect that it can have a productive conversation focused on its long-term strategy.”

Companies may also struggle because investors are becoming more reluctant to lend them money. Appetite for new bonds, especially those issued by less-creditworthy businesses, has fallen off. Banks may also have to tighten lending standards. In a sign that investors believe the coronavirus concerns could hit banks hard, the stocks of the three largest U.S. banks — JPMorgan Chase, Citigroup and Bank of America — are all down by a lot more than the S&P 500 so far this year.

Of course, the coronavirus outbreak could end up resembling other brief shocks that have landed only glancing blows on companies and the stock market. These include the fiscal battles of the previous decade that consumed Washington and Wall Street for weeks at a time.

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And as recently as Friday, some companies were predicting that their sales would hold up just fine. Volkswagen, the German auto giant, said it expected deliveries this year to be “in line” with 2019. And Apple said conditions were gradually returning to normal in China. “It feels to me that China is getting the coronavirus under control,” Tim Cook, Apple’s chief executive told Fox Business on Thursday. “When you look at the parts that are done in China, we have reopened factories.”

Some Wall Street analysts have expressed optimism that the Federal Reserve and other central banks will cut interest rates to help offset the economic stress caused by the virus. Such cuts would help lower borrowing costs, giving consumers a fresh incentive to spend and businesses to invest.

Those hopes were buoyed when the Fed chair, Jerome H. Powell, unexpectedly issued a statement on Friday saying the central bank would “act as appropriate to support the economy.” Economists at Bank of America wrote on Friday that they expected the Fed to cut rates by half a percentage point at its March meeting “as a way to stem panic.”

Some companies are already talking about how much business will come their way when the outbreak begins to recede — including Las Vegas Sands, which has major interests in the Chinese gambling haven of Macau.

An executive at Las Vegas Sands, a casino operator in Macau, expects business to rebound when the outbreak subsides.
Credit…Vincent Yu/Associated Press

“When it does resolve, Macau’s going to be very, very, very busy,” Robert G. Goldstein, the company’s chief operating officer, said in an earnings call last month.

Some analysts appear to be banking on warmer spring weather to curb the virus’s spread. “Fear will subside as the weather warms up, hopefully,” said Barry Bannister, head of equity strategy at Stifel.

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For now, though, investors seem to be expecting things to get worse. After finishing down 0.8 percent on Friday, the S&P 500 lost about 11.5 percent of its value this week, its worst one-week performance since the financial crisis of 2008.

Some investors sit on the sidelines when they feel unequipped to assess financial risks.

A big concern is that the virus will spread quickly in Europe and the United States, forcing consumers to stay home from work, not to mention avoiding stores, restaurants or other businesses.

In that case, an economic contraction could become inevitable. Should a recession develop, the Goldman analysts said, profits of S&P 500 companies are likely to fall this year by 13 percent. Such a decline could force companies to lay off employees and put off new investment.

Even before the coronavirus outbreak, business investment was already pallid in the United States. It fell in the last three quarters of 2019. Some analysts now expect more companies could soon announce reductions in their capital spending. “I think you will see that when they report their Q1 numbers,” Mr. O’Rourke of JonesTrading said.