Now the entire processing industry seems to be talking about the topic of high-speed machining centers. In Japan, Makino is the first machining center developer and has a unique definition of high-speed machining centers. Of course, the powerful development of the powerful drive controller and the professional technology of the machinery industry has become a necessary condition for the machine to achieve amazing precision and speed.
The high-speed machining center may not look much different from the traditional machine tool on the outside. However, the structure and technology inside the machine tool are quite different, not just the use of high-speed spindles or high-speed milling. In fact, not only the spindle, but also the optimization of the technology and design of each part of the servo controller system and the strategic update of the basic mechanical system design are indispensable components for creating excellent high-speed milling. Our definition of a high speed machining center is:
· Provide high productivity;
·High speed spindle;
· Spindle acceleration and feed quickly;
·The tool change and the table rotate quickly;
· Large capacity cutting processing function;
· High reliability is ensured during heavy cutting.
In the process of continuous improvement of high-speed machining centers, we usually study a lot of sound and efficient machine tools. But when we measure the accuracy of machine tools in micrometers or even smaller units, we begin to revisit the definition of efficient machine tools. From the controller system of the machine tool to the bearing, the machine tool builders set out to consider how to effectively update the CNC machine system to improve efficiency, but it is important to achieve the highest operating efficiency of all parts combinations, reflecting extraordinary Consistency and coordination.
Spindle
The receiving high-speed machining center utilizes an integral spindle motor to reduce vibration and prevent heat generation from affecting the spindle. Makino's special application and maintenance of the patented spindle core cooling system is a magic weapon for the Makino high-speed machining center.
Low-speed spindles typically use ball bearings and are grease lubricated. However, as the spindle speed continues to increase, when the spindle speed approaches 10000r/min, the lubricant begins to produce heat and directly affects the spindle accuracy and life. Especially when the spindle speed reaches 12000r/min, the heat generated by the lubricating oil reaches a certain level and then gathers in the spindle and the tool. Today, when customers are constantly demanding machine power and high speed, how to solve the spindle problem is a big challenge for manufacturers.
The prior art is to use a hybrid ceramic bearing to match the lubricating oil. Such a technique may not be a problem for the spindle at 15000 r/min. We have also found that some manufacturers also use another type of bearing, the inner and outer edges of which are still composed of sheet metal, but the rotating part is made of a very rigid and durable ceramic material. Heat is a natural enemy of bearing accuracy and life. When the spindle is running to 10000r/min, it is more representative to use the Oil Air Lube instrument system. This system provides the least (but sufficient) lubricant to reduce the heat generated by the bearings, and the blowpipe also helps dissipate heat. The remaining heat is transferred to a cooling system that does not cause circulation and is enclosed.
The Makino spindle does not use the oil mist meter system, because the lubrication spindle should be completed when the oil mist spindle speed is lower than 15000r/min; but when the spindle speed exceeds 15000r/min, the high speed rotation produces a protective airflow outside the spindle. . The higher the spindle speed, the more closed the gas barrier is, so that the centrifugal force generated by the rotation does not allow the lubricant to sufficiently lubricate the spindle. At the same time, the heat inside the main shaft is not sufficiently diverged, and of course it is impossible to cool it quickly. Over time, the spindle produces a lot of wear, which affects the accuracy of the workpiece.
Makino's handling of the cooling problem of the main shaft is very reasonable. The spindle core cooling system we use is unique. The coolant inside the spindle first cools the inner core of the spindle. The spindle center cooling system uses a large number of temperature-controlled cooling oils that cool directly from the inside through the rotating spindle. This ensures that even with a rigid spindle with an 80mm inner diameter bearing, thermal displacement does not occur at high speeds. Second, re-cool the spindle housing to ensure a balanced spindle temperature. In addition, the lubricating oil we use is also a cooling oil. The internal pressure lubrication means that the cooling oil flows from the inside of the main shaft to the inner ring of the bearing, and then passes through the hole in the inner ring of the bearing while cooling the entire bearing. Since the centrifugal force when the inner-cooled bearing rotates coincides with the flow direction of the cooling oil, even in the case of high-speed rotation, the smooth lubrication can be ensured (patented). Therefore, the lubricating oil, that is, the cooling oil, directly lubricates the balls through the inner race of the bearing. The field is called Under-Race Lubrication. We have tested that the spindle speed of Makino is three times faster than the aforementioned spindle with oil mist.
Faster feeds (Quicker Feeds)
Makino continues to provide high-speed machining center efficiency while ensuring high precision. Makino equipment A55e, J66 X, Y, Z axis feed speed pair to reach 50m / min. In order to achieve such a large feed, there must be special system support. Makino uses dual ball screws and dual feed motors. The double ball screw ensures that the spindle X, Y and Z feeds are averaged and stable in three directions; the double ball screw also preloads during assembly, maximally eliminating the gap problem caused by the single ball screw. Similarly, the dual feed motor also provides a smooth and efficient power system for the spindle.
Is the use of a double ball screw and a double feed motor also increase the heat generation? The answer is of course no.
Ball Screw Core Cooling is the best way to deal with heat. The use of lubricating oil to circulate inside the ball screw is 100 times less than the heat generated by the outside of the screw.
Controller - Makino's unique geometric intelligence function GI (Geometric Intelligence Function)
Past experience has proven that the main obstacle in high-speed machining (high speed and high precision) is the operation control technology rather than the spindle technology. CNC manufacturers have not made much progress in this area in the past few years. Thanks to the rapid and powerful computer functions, To make up for this deficiency, especially the maturity of software and the rapid development of digital technology.
First, current machining centers can process data faster and speed up workpiece processing. A small number of machine tool manufacturers boast that their machine tools process speeds of less than 1ms per line in high-precision machining, which is a significant improvement compared to 70ms 10 years ago. Users must be vigilant, because these vendors only provide the speed of program processing. In fact, the processing speed of the program is not important. The time that the machine finishes running the program is the actual problem we care about. One thing we must understand is that the actual machine running time determines how fast you can process. The accuracy here, the traditional meaning refers to the error caused by the linear interpolation using the point to simulate the contour of the machined shape. This means that the higher the precision, the more analog points there are, and the smaller the distance between the points. When the machine data processing speed is not enough, the dense point will lead to a problem commonly encountered in mold processing "data starvation".
Geometry intelligence can solve the "data starvation" problem that is common in processing. He is mainly used for high-precision machining of workpieces, which reduces the work cycle and makes the workpiece more perfect than other "Look Ahead" high-speed machining technology.
Of course, in addition to the reliable spindle, fast feed, and GI control system, Makino's high-speed machining center has a reasonable shaft structure and pleasant host structure, efficient cooling system and a unique HSK tool holder (dynamic balancing knife). handle). These are the core parts of creating high-speed, high-precision machining centers. It is precisely because of this concept of continuous improvement of customer productivity, Makino machine tools have a good performance in the Chinese mold and parts processing industry.
The Northeast Office of the State Council has selected several cities in the central region to measure the value-added tax reform. The State Administration of Taxation is also studying the pilot program for VAT reform in the central region. These messages are all suggesting that the next step in the VAT transformation pilot will be “flowering down†in the middle.
However, people familiar with the matter recently revealed that the relevant departments are still weighing the two options of “continuing the pilot†and “national promotionâ€. The central “inheritance†program, which seems to have been clear, has fallen into a fog.
Has the pilot area become a “tax-free port�
Experts who support national promotion said that if the VAT transition is piloted in some regions for a long time, the tax avoidance effect will lead to distortion of resource allocation.
"The pilot of the three provinces and one city in the Northeast is like an arrow that can't be recovered." According to industry insiders, if the six central provinces become another arrow, then China will have nine provinces and one city to obtain "tax incentives." Even if only the old industrial bases in the central part receive preferential treatment, this regional effect will soon spread to the entire central region. Moreover, the western and eastern provinces and regions will also rush to request pilots.
As a result, resource allocation is artificially distorted, and some regions and industries are allowed to deduct. Other regions and industries cannot enjoy such treatment, and the decisions of microeconomic entities will be disrupted. "This will increase the cost of collection and management, increase the tax refund procedures, and even induce some enterprises to evade taxes and tax evasion." Zhang Bin, from the Institute of Finance and Trade of the Chinese Academy of Social Sciences, said with no worries.
One possible phenomenon is that two affiliated companies, one located in the middle and the other in the east, purchase enterprises in the central part of the country and then transport them to the east for use. This is reminiscent of the tax exemption from the mainland to Hong Kong. The phenomenon of cosmetics being sold to the mainland for sale. Moreover, this is most likely to occur in companies around the pilot area.
"The pilot can't be dragged on for too long. The Northeast Pilot has accumulated a lot of experience and has laid the foundation for the comprehensive opening of the future. Do we still need to go to the central pilot to accumulate experience?" Industry experts asked.
Adding oil to the investment overheating?
The VAT transition may lead to investment impulses in some industries and enterprises, and it is one of the main reasons for the delay in the nationalization of the transformation pilot. At present, China is at the peak of investment. In the first quarter of this year, urban investment totaled 1,160.84 billion yuan, a year-on-year increase of 29.8%.
Experts said that the VAT reform is not the reason for the faster investment. The further pilot or opening of the VAT will not necessarily lead to excessive investment. Wang Yuanjing, a researcher at the Investment Research Institute of the National Development and Reform Commission, pointed out that the current investment is too fast, mainly due to the local government investment and new rural construction driven by the “Eleventh Five-Year Planâ€, as well as the transfer of excess capacity of the pre-steel and other industries to the automobile and real estate industries.
“The purpose of corporate investment is to make profits, not to enjoy tax incentives,†said Sun Gang, the tax research office of the Finance Department of the Ministry of Finance. “If there is no profit, no more preferential offers can attract investment. The Northeast pilot can also prove that enterprise equipment is updated. The technological transformation will not increase significantly due to the VAT reform."
In addition, the northeast pilot program has imposed certain restrictions on the scope of deduction. If the Northeast model is still adopted in the next step, the investment pulling effect generated by the VAT deduction will be much smaller. The value-added tax deduction in Northeast China is limited to eight industries including equipment manufacturing, petrochemical industry, metallurgy industry, shipbuilding industry, automobile manufacturing industry, agricultural product processing industry, military industry and high-tech industry. On the deduction standard, the principle of incremental deduction of movable assets such as machinery and equipment is implemented, and real estate is not within the deduction range. Who will bear the financial reduction?
The VAT reform is inevitably causing fiscal revenue reduction while reducing the burden on corporate fixed assets investment. This has become another important reason for the slow progress of this reform.
Industry insiders judge that the VAT reform involves half of the fiscal revenue. The data shows that in 2005, China's domestic value-added tax revenue was 107.1 billion yuan, and the import-related value-added tax revenue was 416.6 billion yuan, accounting for 34.7% and 13.5% of the total tax revenue, respectively, which is the "top pillar" of taxation.
An Tifu, a professor of finance and finance at Renmin University of China, predicted that if the pilot project in the northeast is pushed across the country and is still limited to incremental deductions in eight industries, the tax reduction will be about 40 billion yuan to 50 billion yuan; The whole country will be rolled out and the deduction will be extended to all fixed assets investment, at least 70 billion yuan will be reduced.
A person familiar with the pilot project in the northeast region told the reporter that due to the lack of funds for reform in the northeast, although there are preferential policies, the investment of enterprises is not active, and no investment can not be deducted. Therefore, if VAT reform is implemented in areas with high investment activity, there may be more fiscal reductions.
However, many experts said that China’s financial resources are sufficient to bear the cost of tax reform. "China's annual tax revenue is about 500 billion yuan, and it is fully capable of undertaking the cost of reform." Zhang Bin said. The data shows that in the first four months of this year, China's fiscal revenue exceeded 1.5 trillion yuan, a year-on-year increase of 22%.
Resistance from local finances may be even greater. According to informed sources, it has been suggested that the local finances should digest the fiscal reduction caused by the reforms, but the local finances have considerable opinions.
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