The first is that workers can’t afford
According to a simple example, how many tuition fees are eager for everyone, I don’t know, let’s count 300,000 (I think it’s less to tell me), and train eight-level fitters to cost more than this number, and the time is relatively It will be much longer. Is the 8-level fitter finished? I have to go to study from time to time, and I have to give him a difficult job often (small factories can't afford it), otherwise the hands will be unfamiliar (not in this respect than the surgeon), the benefits are slow, you cultivate A high-level worker can't do it every 5-8 years. Besides, if you train it, what will happen to him? Will it be safe to stay in your heart, it is hard to say, this is a lot of factories are not willing to raise funds to train workers.
Secondly, there is no such energy to build the machine tool.
In a simple example, the tool rail of a horizontal milling machine is a cylindrical hollow rod. However, what are the techniques that he wants to make? First of all, raw material selection, flaw detection, stress test... (Many in order to save costs, many will save this step), this step will be nearly two months, not necessarily available. Next, roughing, semi-finishing, these simple, about 20 days on the line (the domestic generally only the outer surface, the inner surface is only rough processing, Germany generally processing, in order to maintain the same stress deformation).
Then heat treatment, semi-finished again, this is more troublesome, about a month. Then throw it into the outdoor storage, eliminate the internal stress (the domestic one will save this part, use heat treatment to eliminate). About a year. The next step is the focus of work. We also take Germany as an example. This is the number of workers required to process a cylindrical beam. One engineer, two technicians, and 3-5 senior workers (about 8 in the country). This section is also very time consuming, about half a year (including finishing and surface treatment, as well as repair). In this way, it takes at least two years for a machine to be built (it should be placed in the field for one year after the machine is assembled, eliminating assembly stress, which is the same as in China).
In this way, unless it is a large-scale enterprise, small businesses can not afford such expenses and time. Our country is not willing to spend so much time on this, so high-precision machine tools have not made much progress (at the time he was not the biggest constraint). However, the mechanical industry as the cornerstone of the national industry has become the weakest link, and various aspects have begun to pay attention to the development of the machinery industry. It is estimated that there should be more progress in the near future.
I have been to Changchun Machine Tool Plant, Changzhou Machine Tool Plant, Shanghai No. 1 and No. 2 Machine Tool Plant. Also, the stress-relieving method you mentioned is long gone, and there are many methods for stress-removing. Heat treatment is one kind, as well as electromagnetic wave treatment and shock treatment. The main shaft grinding machine can be subjected to surface ion nitriding treatment. At 75HRC, China's Shanghai Machine Tool Plant has produced a 3-stage precision grinding machine. What else? ? ? ? It is said that the difference between Chinese machine tools is mainly in the quality and numerical control servo system, and the responsibility of the employees is determined. Many of the things I see are that they can be knocked in with a hammer if they are not matched, and the floating jaws are not used to ensure the shape error of the holes.
2 CNC servo system is a serious injury. China mainly uses Siemens and Japanese Franck systems. It is much worse than the China Central 3 type. It is not the case for high-speed tools and high-speed cutting. The tool materials cannot work in the environment above 6000 rpm. Mainly in the regular machine can now go to 50,000 rpm but the foreign has reached 150,000 rpm and the main difference in the servo motor is not what you said, the spindle you use high-precision lathe, the grinding machine after processing is not much, mainly With the positioning of the bearing, the accuracy is determined by the precision of the bearing and the cooperation of the machine tool.~~~~~~~ Don't know if you don't know~~~~
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