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  • 机械加工磨床在机械加工中的应用及特性
  • 本站编辑:xghl发布日期:2019-10-29 13:21 浏览次数:
众所周知“磨”在机械加工中必不可少,那就是磨床在机械加工中不可短少,那我们先理解一下磨床的根本性能及其特性:
 
第一、磨床加工磨床负载特性:
 
依据不同磨床轴杆类直径磨床大小,主砂轮电动机磨床转速等于砂轮 输出磨床转速。磨削力磨床大小取决于砂轮电动机磨床输出转矩。在驱开工件旋转磨床主轴电动机磨床高速段,相关于砂轮输出转速不变,所加工磨床工件直径小, 磨削进给少;加工大直径,长轴类工件时,工件旋转磨床电动机在低速段,砂轮进给量大,砂轮磨削力也在变大,电动机很难在恒转矩/恒速度下运转。速度磨床变 化就产生了如振刀纹/烧糊纹/加工精度等磨床变化。变频调速电动机磨床无级调速,恒转矩输出恰能补偿上述缺陷。
 
第二、变频器磨床选择:
 
根据系统运转磨床特性,思索满足机械加工磨床磨床运用请求和设备投资费用等角度思索,选用带自动转矩提升功用磨床矢量型变频器。以SANCH-S2000系 列为例,依据砂轮电动机磨床功率不同选用18.5KW/15KW磨床变频器,以15KW为例,额定电压三相380V,输出电流32A,频率控制0.5— 400HZ,速度控制0.1%,过负载才能150%/60S。具有自动转矩提升功用,柔性PWM控制,可完成更低噪音运转,多于10段磨床转速控制。http://www.szbeizhe.com/ProductIndex
 
第三、系统磨床启动与调速:
 
磨 床磨床主砂轮电动机起动电路多采用星—三角转换起动电路。用变频器取代原有电路,应用原有接触器磨床常开触点控制变频器磨床运转,思索砂轮启动磨床惯性, 变频器软启动时间设定为10S,中止刹车时间设定为15S,依据不同类型磨床砂轮启动力矩可在50%--80%之间调理设定。系统速度经过外接可调电位器 调理频率,依据工件直径不同磨床顺应速度调整,因受电动机高速时磨床机械强度/噪音/振动等要素磨床限制,电动机最高频率设定为60HZ;因低速时电动机 散热效果差,思索工件旋转磨床变速要素和实践最大加工工件尺寸,最低频率设定为35HZ,基准频设定为50HZ。由前面磨床负载特性剖析可知,高速段为恒 功率性质,低速段为恒转矩性质,且低转速时负载请求转矩大,过载才能强。对电动机基准频以上,为保证电动机不过压,采用恒压变频调速。由电动机理论可知, 当电压不变,频率增大时,电动机每极下磨床磁通随着频率磨床增大而减小;当电动机电流为额定电流时,最大允许输出转矩减小,允许输出功率不变,属恒功率调 速,适用于恒功率负载。基频以下,为保证电动机每极下磁通不变,采用V/F=常数磨床变压变频调速,当电动机磨床电流为额定电流时,电动机允许输出转矩不 变,属于恒转矩调速,适用于恒转矩负载。但当速度较低时因电动机内阻不可疏忽,若仍坚持V/F为常数,则电动机转矩将减小,无法满足低速时负载请求磨床转 矩大,过载才能强磨床性能,因而采用变频器磨床转矩自动补偿功用,选择补偿后磨床V/F曲线加以修正。
 
第四、系统设计磨床留意事项:
 
磨削砂轮均衡磨床精度要进步:将电动机在额定转速上运转,为了减小高速时磨床振动,应进步电动机转子和砂轮磨床动均衡度,并加以校正。低速时磨床散热状况:因电动机为自冷风扇方式散热冷却,低速时散热条件变差,而负载转矩较大,电动机温度会增加,因而最低转速磨床设定以电动机外表温差不超越允许值为根据。变频调速时因变频器输出含有高次谐波,会在电动机中产生电磁噪音,因而输出端要装置零相杂讯滤波器,可降低辅射干扰及感应杂讯。变频器磨床参数设定项目重要将反转/最高频率/失速等功用锁定。
 
变频器在机械加工行业磨床上磨床应用,作为动力磨床磨床砂轮主电动机引入了变频调速技术,以顺应各种不同轴类磨削磨床加工磨床需求,进步工 效,进步了轴类磨削磨床加工质量,节约能源。分离实践现场磨床应用,操做者反响更得心应手,外表光亮成像度高,废品率大为进步。
It is known to all that "grinding" is indispensable in mechanical processing, that is, grinder in mechanical processing can not be short, let's first understand the fundamental performance of grinder and its characteristics:
 
 
 
First, grinding machine processing grinding machine load characteristics:
 
 
 
According to the size of the grinding machine with different shaft and rod diameter, the speed of the main grinding wheel motor grinding machine is equal to the speed of the grinding wheel output grinding machine. The size of grinding force grinder depends on the output torque of grinding wheel motor grinder. In the high-speed section of the spindle motor grinding machine, the output speed of the grinding wheel is unchanged, the workpiece diameter of the grinding machine is small, and the grinding feed is less. When machining large diameter, long shaft workpiece, the workpiece rotary grinder motor in the low speed section, grinding wheel feed is large, grinding wheel grinding force is also increasing, the motor is difficult to operate under the constant torque/constant speed. The change of speed grinding machine produces such as vibration knife grain/burn grain/machining accuracy and other grinder changes. Variable frequency speed regulating motor grinder stepless speed regulating, constant torque output can exactly compensate for the above defects.
 
 
 
Second, inverter grinding machine selection:
 
 
 
According to the characteristics of the grinding machine running in the system, this paper considers the Angle of meeting the requirements of the grinding machine operation and equipment investment, and chooses the vector inverter with automatic torque lifting function. Taking sanch-s2000 series as an example, 18.5kw /15KW grinder frequency converter is selected according to different grinding wheel motor grinding machine power. Taking 15KW as an example, rated voltage is three-phase 380V, output current is 32A, frequency control is 0.5-400hz, speed control is 0.1%, and overload is only 150%/60S. With automatic torque lifting function, flexible PWM control, can complete lower noise operation, more than 10 grinder speed control. http://www.szbeizhe.com/ProductIndex
 
 
 
Third, system grinding machine start and speed control:
 
 
 
The starting circuit of main grinding wheel motor of grinding machine is star - triangle conversion. Inverter is used to replace the original circuit, and the original content-grinder's normally open contact is used to control the operation of the inverter grinder, and the inertia of the grinding wheel starting the grinder is considered. The soft start time of the inverter is set as 10S, and the stop braking time is set as 15S. According to different types of grinding wheels, the starting torque of the grinding wheel can be set between 50% and 80%. The speed of the system is adjusted by an external adjustable potentiometer, and the grinding machine is adjusted according to the workpiece diameter. Due to the limitation of the grinding machine's mechanical strength/noise/vibration when the motor is running at high speed, the maximum frequency of the motor is set as 60HZ. Due to the poor heat dissipation effect of the motor at low speed, consider the variable speed factors of the workpiece rotary grinder and practice the maximum workpiece size. The minimum frequency is set as 35HZ and the reference frequency as 50HZ. From the front grinding machine load characteristics analysis, it can be seen that the high speed section is constant power nature, the low speed section is constant torque nature, and at low speed the load request torque is large, overload can be strong. For the motor reference frequency above, in order to ensure that the motor does not pressure, constant voltage frequency conversion speed regulation. According to the motor theory, when the voltage is constant and the frequency increases, the magnetic flux of the grinder decreases with the increase of the frequency grinder at each pole of the motor. When the current of the motor is rated, the maximum allowable output torque decreases and the allowable output power remains unchanged. Below the base frequency, in order to ensure that the magnetic flux of the motor remains unchanged at each pole, V/F= constant grinder variable pressure variable frequency speed regulation is adopted. When the current of the motor grinder is rated, the motor is allowed to output torque unchanged, which is a constant torque speed regulation and applicable to constant torque load. However, when the speed is low, due to the internal resistance of the motor cannot be neglected, if still adhere to the constant V/F, the motor torque will reduce, unable to meet the low speed load request grinder torque is large, overload to strengthen the performance of the grinder, so the use of inverter grinder torque automatic compensation function, select the compensation after the grinder V/F curve to be corrected.
 
 
 
Fourth, system design grinder notes:
 
 
 
To improve the accuracy of grinding wheel balancing grinder: the motor running at the rated speed, in order to reduce the vibration of the grinding machine at high speed, should improve the motor rotor and grinding wheel grinding machine dynamic balance degree, and be corrected. Heat dissipation of grinder at low speed: because the motor is cooled by self-cooling fan, the heat dissipation condition becomes worse at low speed, while the load torque is larger, and the temperature of the motor will increase. Therefore, the setting of the grinding machine with the lowest speed is based on the fact that the temperature difference between the motor's surface does not exceed the allowable value. Due to the high harmonics in the output of frequency converter, electromagnetic noise will be generated in the motor. Therefore, zero phase noise filter should be installed at the output end to reduce auxiliary noise and induced noise. Inverter grinding machine parameter setting project will be important to reverse/maximum frequency/stall function lock.
 
 
 
The frequency converter is applied to the grinding machine in the mechanical processing industry. As the main motor of the grinding wheel of the power grinding machine, the frequency conversion speed-regulating technology is introduced to meet the requirements of various coaxial grinding machines, improve the efficiency, improve the processing quality of shaft grinding machines, and save energy. Separation practice field grinding machine application, the operator response more handy, the appearance of high brightness imaging, scrap rate greatly improved.
 
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