Gift Tape,Pu Leather Retractable Tape Measure,Matt Tape Retractable Tape Measure,Retractable Tape Measure Shangqiu Jinda Tools Co.,Ltd , https://www.jindameasuring.com
/*728*90 created on 2018/5/16*/ var cpro_id = "u3440131"; Home>Bearing knowledge>High-speed spindle system of CNC gold cutting machine (2) High-speed spindle system of CNC gold cutting machine (2)
More than a few years; due to the advent of ceramic cylindrical hybrid bearings and the smooth use of oil and gas; the high-speed function of cylindrical roller bearings has been greatly improved; so now there is a suitable number of high-speed machining in the middle; the rear bearing of the electric spindle is selected Cylindrical roller bearings that allow for greater relative movement of the inner and outer rings and can accept greater radial loads (Fig. 4). This allows for progressive stiffness; The intention of swelling; the high-speed electric spindle produced by Step-Tec in Switzerland; after that, the bearing is a ceramic cylindrical hybrid bearing. /*250*250 was created on 2017/12/25*/ var cpro_id = 'u3171089';
High-speed electric spindles are used in addition to rolling bearings; there are several other types of bearings to consider:
Hydrostatic bearing. The hydrostatic bearing is very poor due to the rigidity and especially the bearing; although the reversal precision is high and the conflict is lost. The warehouse is ridiculously ridiculously provoked by Xing Yi Han Shan Benz 〉 鲜 fresh 褂. Oil hydrostatic bearing During high-speed reversal; turbulence occurs in the oil sac; liquid collision force also increases with increasing speed; large power loss and severe heat generation are formed; therefore, high-speed reversing cutting machines are still rarely used (IBAG has There is a high-speed 32000r/min oil-static bearing electric spindle supply. In addition; FISCHER is developing a hydrostatic bearing electric spindle called Hrdro-F; the maximum speed is 36000r/min (power 67kW) ).
Dynamic and static bearing. It uses fluid dynamics and hydrostatic force to make the main shaft reverse in the oil film support; it has the advantages of dynamic pressure bearing and hydrostatic bearing; high rigidity and precision; large damping; long life It has been used in the horizontal machining center of Ingersoll spindle with a maximum speed of 20000r/min and some high-speed grinding machines. However, this kind of bearing will exceed the line speed of the spindle journal beyond 50m/s; the oil flow will also change from laminar flow. It is a turbulent flow; it also presents the problem of severe heat generation and power loss; its further high speed is still a subject being studied; and it has always been the focus of the industry.
Magnetic bearing.
It is a kind of high-performance bearing that uses electromagnetic force to suspend the main shaft in the air; and continuously detects the spindle orientation with the active sensor at the top of the operation; and feeds back to the manipulator to adjust the electromagnetic force in real time; and makes the rotor (bearing rotor and motor) The rotor of the rotor) has always adhered to the correct orientation. Due to the selection of the electronic feedback system for active conditioning; its stiffness and damping are controllable; the spindle can be actively balanced; its reversal accuracy can be as high as 0.1 μm. Touch; long life; its high-speed function is only limited by the centrifugal force of the rotor steel sheet; the maximum linear speed of the rotor can reach 200m / s. Clear and clear; magnetic floating bearings are suitable for high-speed high-precision cutting machine tools; The cost is very high; at that time, the practice was not much used on the machine tool. German GMN company and Swiss IBAG company have sold the maglev bearing electric spindle (the two types of IBAG produced the highest speed of 70,000r/min and 40,000r/min).
The dynamic balance of the high-speed spindle and the centrifugal force of the HSK shank are proportional to the square of the spindle speed; when the spindle is reversed at high speed; the small unbalance will also cause a large centrifugal force; the machine oscillation will affect the machining quality; therefore, the dynamic balance is the high-speed spindle. The system needs to be carefully handled. The electric spindle produced by the professional electric spindle factory has passed strict dynamic balance; it usually fulfills the ISO specification G0. 4 (G=ew; e is the displacement between the middle of the mass and the middle of the reversal; The amount of pain is too much; w is the angular velocity); that is, the maximum oscillating speed caused by the residual unbalance at the maximum speed must not exceed 0. 4 mm / s. The generalized spindle system also includes the tool; each tool is replaced during the machining; The dynamic imbalance will change. For this reason, FISCHER supplies an online active balancing device; it can actively measure the unbalance of the spindle system; and actively rotate the two balancing disks at the front end of the electric spindle to one. The position with the least amount of imbalance.
Beijing Machine Tool Research Institute μ1000 series fine vertical machining center; on the base of FANUC spindle motor; self-made electric spindle with the maximum speed of 15000r/min. The electric spindle passed two accurate dynamic balance during the production process; One is after the rotor is hot-loaded; the second time is that all the reversing parts are installed and several precision inspections are completed. Together, there is a balance ring in front and rear orientation of the electric spindle for online dynamic balancing.
The connection between the spindle and the tool is related to the processing quality; nowadays, all professional electric spindle manufacturers can supply various specifications and non-standard tool interfaces according to the user's needs; of course, different tool interfaces correspond to different tool holders. Traditional 7:24 solid shank; only the taper surface is positioned with the spindle hole; when the spindle rotates at high speed; the spindle taper hole will "swell" due to the effect of centrifugal force; but the solid taper shank cannot be "expanded"; the spindle hole The attack "open mouth" causes the cutter to shake between them; then the axial positioning error occurs and affects the dynamic balance of the spindle system. Therefore, another HSK tool holder with high speed function has been agile in the past 10 years; more and more High-speed machining machine tools are selected; in 2001, it has been listed as an international standard ISO12164-1:2001.
The HSK shank is a hollow taper shank with double taper and end face positioning; its taper is 1:10 and the cone is relatively short; under the effect of axial pull of the tie rod; the thin-walled cone of the shank will have a certain elastic deformation; The short cone and end face of the shank are closely attached to the tapered hole and the end surface of the main shaft. Figure 5 shows the connection between the HSK shank and the main shaft. The upper part of the figure is the condition before the shank is tightened; There is a space h between the end faces of the main shaft, and the lower part of the figure is the condition after the tension; the elastic deformation of the thin-walled cone of the shank eliminates the gap h. At the time of high-speed rotation; due to the thin-walled cone of the shank With the "expansion" of the spindle cone, it will "swell"; therefore, there will be no gaps in the middle; the end faces of the two will not separate; therefore, the HSK holder has excellent joint rigidity with the spindle during high-speed machining; natural cutter Can always adhere to high positioning accuracy; and HSK tool holder is shorter and lighter; it is beneficial to improve the speed of tool change in the middle of processing.
HSK series holders are of type A, B, C, D, E, F, etc. The most used ones are type A and type E. HSK? A type handles have keyways; when suitable cutting load is large, use HSK?E The type does not have a transmission key; only the conflicting force between the cones is used to transmit the torque; the appropriate cutting load is used for hours.
Conclusion Although the cutting speed of the machine tool still has a lot of space to develop; but the highest speed of the international high-speed machining machine spindle in the past three years; seems to have entered a relatively stable development stage. Take the middle of high-speed machining as an example; The product is basically: small 20,000~60000r/min, medium 10000~30000r/min, large (heavy) 8000~24000r/min. Information obtained from EMO2003; the maximum number of revolutions of intermediate products in processing is 10000~ 30000r/min; the highest is 60000r/min.
Today, the spindle system of high-speed cutting machine tools mainly uses electric spindle unit; the bearing of electric spindle is basically rolling bearing; its dmh value usually does not exceed 250×104. From the research and development situation at that time; in the near future, it can It reaches 300×104 or even higher; that is to say, the inner diameter of the rolling bearing is Φ50~55mm; its maximum speed is expected to reach about 50000r/min. The higher speed needs hope for the magnetic bearing; the key to the promotion of the magnetic bearing It is necessary to reduce the cost; together, we must also consider the problems of heat and magnetic flux leakage. In addition, the problems associated with the electric spindle; for example, integrated sensor monitoring, small high-output spindle motor, lightweight spindle, etc.; are deepening the discussion.
At present; there are few domestic manufacturers of electric spindles; domestic electric spindles have not yet been able to satisfy the market demand (at CIMT2003; domestic CNC machine tools equipped with electric spindles as long as 23.8% are domestic products). However; Category; China has already had a certain foundation and talent; at that time, the state clearly supported the implementation of the domestic CNC machine tool components; we should seize the opportunity; accelerate the development of domestic high-speed electric spindle.
Recommend to friends comments close window Bearing related knowledge What is the outer dimensions of the bearing?
Metallurgical defects in bearing steel
Intent and criteria for preloading of NSK bearings
The cause of wear failure of NTN bearings
NTN Bearing Review and Repair New Skills
This article links to http://
Please indicate China Bearing Network http://
Previous:Production characteristics of rolling bearing parts Next:The analysis of the application method of SKF bearing
High-speed spindle system of CNC gold cutting machine (2)
Source: Bearing network time: 2013-03-07