张力控制问题与故障.doc

张力控制问题与故障7.1张力控制原理及技术参数“金明”吹膜收卷中采用张力传感器、张力信号放大器，PLC组成张力控制系统，实现闭环张力控制。在张力闭环控制中，张力传感采用的是应变片电桥测试原理，采用穿轴式或支座式安装使用，能精确测出薄膜施加在张力辊上的力，根据所受的力的大小，输出与之成正比的电压信号，在吹膜设备上采用ZC穿轴式张力传感器或三菱支座式张力传感器。ZC穿轴式张力传感器具有方向性，红点为合力方向。ZC穿轴式张力传感器技术参数供电电压612V，输出电阻350欧姆，灵敏度2mv/V，电气连接1、电源+，4、电源-，2、信号+，3、信号-，其他详细技术参数及三菱支座式张力传感器详见相应的说明书。张力信号放大器与张力传感器配套使用，它为张力传感器提供必要的校准及调零电压，并将传感器的检测信号放大后输出，这些信号通过PID控制器或PLC控制牵引或收卷变频器，实现闭环控制。TAC100-020及TAC100-020A技术参数：电源：24V张力传感器电源：12V张力传感器输入信号：20mV其他控制信号输入与输出：0-10V其他详细技术参数及TE-PC或LM-10TA使用说明详见相应的说明书TAC100-020A配线端子定义（粗体蓝色部分为控制器信号输出，其他为信号输入）24V（+）、0V（-） 电源输入端VCC（+）、GND（-） 张力传感器用电源12VTR1（-）、TR2（+） 张力传感器（右）信号输入用0-20mVTL1（-）、TL2（+） 张力传感器（左）信号输入用VO（+）、COM（-） 实际张力输出0-10VA1（+）、A1（-）张力设定值0-10VA2（+）、A2（-）前一级速度信号（同步线速度）0-10VAP（+）、COM（-） 控制变频器速度输出0-10VZERO电位器调零SPAN电位器校准R1电位器 积分时间粗调10-250SR2电位器 积分时间微调1-50SR3电位器 增益调整R4电位器 同步信号调整其他张力信号放大器或控制器具体连接线定义及方法可详见具体的使用说明书。7.2控制方案“金明”设备主要采用两种张力控制方案：使用张力传感器，TAC100-020A（张力信号放大PID控制器，简称张力控制器），张力控制器直接控制变频器、同时将实际张力输出给PLC以供显示实际张力大小，PLC输出给张力控制器张力设定。（调校步骤1、2、3）7.3张力调较张力调较步骤:7.3.1同步线速度的调整（仅用于TAC100-020A）张力控制是在上一级的线速度的基础上进行速度微调，同步线速度的调整的好坏直接影响到张力的控制精度。此步骤在设备出厂时已经过调试，客户无须调整。但如果客户有更换张力控制器或更改过牵引及收卷装置（如变频器、减速箱等）后张力控制失灵，要重新此步骤的调较。同步线速度可用仪表测量或在张力稳定的条件下查看各变频器的实际频率得到同步线速度的具体数值。调校方法： 短接C2与OV端子，拆除原C3联接线（或者将C3连接线接到C2，PLC面板打到速度模式）。 启动第一、二牵引，内、外收卷，第一牵引设为25Hz。 调整R4电位器使第二牵引，内外收卷的线速度与第一牵引保持一致。 线路复原。 此步骤调整完毕例：“用仪表测量线速度”调较的方法部件调整前调整后实际线速度实际频率实际线速度实际频率第一牵引30m/min25Hz第二牵引33m/min25Hz30m/min22.7Hz外收卷36m/min25Hz30m/min20.8Hz内收卷36m/min25Hz30m/min20.8Hz在“张力稳定的条件下查看各变频器的实际频率得到同步线速度的具体数值”调校的方法张力稳定的具体数值调整前调整后实际线速度m/min实际频率Hz实际频率Hz实际频率Hz第一牵引未知252525第二牵引未知22.72522.7外收卷未知20.82520.8内收卷未知20.82520.87.3.2调零和校准张力传感器属于精密元器件，在使用和运输过程中，由于有可能受到外力的作用或者元器件老化的因素，都会造成张力传感器的轻微变形，因此张力传感器应当定期进行调零与校准工作（建议3个月检测一次）。在调零与校准工作前，应对张力辊做一下检查：检查张力传感器的合力方向是否正确，ZC穿轴式张力传感器红点为合力方向。检查张力辊是否转动灵活。检查张力传感器插头是否松动。张力信号放大器或控制器配接线是否断路或短路。TAC100的调零和校准方法： 调零在张力辊不受力（空轴）的情况下，调整ZERO电位器（顺时针输出增大，逆时针输出减少），用电压表检测VO、COM输出电压，使其输出为零。观察PLC操作界面，察看实际张力是否为零。 校准在张力辊上按照膜路方向吊挂标准砝码（5Kg），砝码必须在各辊的中心，调整SPAN电位器（顺时针输出增大，逆时针输出减少），用电压表检测VO、COM输出电压，使其输出为相应值。观察PLC操作界面，察看实际张力是否为5Kg。例：传感器最大张力=30Kg标准砝码=5KgVO、COM输出最大电压=10VVO、COM端电压=VO、COM输出最大电压*砝码重量/传感器最大张力（Kg）=10*5/30=1.67（V）调整VO、COM输出电压为1.67V 检查此步骤目的为验证张力传感器的可重复性是否正常。张力辊不受力（空轴）检查检测VO、COM输出电压是否为零，观察PLC操作界面，察看实际张力是否为零。吊挂标准砝码（5kg）用电压表检测VO、COM输出电压，使其输出为相应值。观察PLC操作界面，察看实际张力是否为5kg左右。如果检查数值偏差较大，需检查张力辊是否正常？吊挂砝码的方式是否正确？再次校准。注：其他型号的调零校准方法详见具体的使用说明书。7.3.3测试测试的目的是检测1、2步的调较是否正确，检测张力控制器是否正常，为正常生产做准备。 启动第一、二牵引，内、外收卷，第一牵引设为25Hz PLC操作界面上设置为张力模式 设定第二牵引张力为5kg(此时实际张力为0kg) 空载时，观察第二牵引实际速度是否高于同步时速度3Hz左右 对第二牵引张力辊施加外力大于5kg（可用手按受力方向压张力辊,使实际张力5kg） 第二牵引会慢速下降，观察第二牵引实际速度是否低于同步时速度3Hz左右 内外收卷张力测试同二牵引 张力检测完毕,.例：同步数值可参照调校步骤1方法得到同步数值空载加载实际频率Hz实际频率Hz实际频率Hz第一牵引252525第二牵引22.725.7左右19.7左右7.4张力控制器高级调较此部分一般为在线调整，出厂已调整好，无须调整，当张力控制失常时，先检查张力传感器、膜路是否正常，排除其他故障依然无法解决时，由专人调整。调整时请注意调整前数值和参数，防止控制继续恶化。调整前应先进行调校步骤1、2。调整时先调整张力稳定性，再调整张力偏差。稳定性主要表现在张力波动较大。张力偏差主要表现实际张力与设定张力存在偏差，张力稳定但较长时间实际张力无法与设定张力相同。调整方法:调整控制器R1、R2、R3，当张力波动较大时，先逆时针调整R2，再逆时针调整R1，如果张力波动还较大，可再逆时针调整R3，直至张力稳定。张力偏差主要是调校步骤1没有调较好，重复调校步骤1。R1 时间粗调，顺时针调整数值越大，反应越灵敏，但过大则容易张力振动。R1 时间微调，顺时针调整数值越大，反应越灵敏，过大则容易张力振动。R3为增益调整，顺时针调整数值越大，反应越灵敏，逆时针调整数值越小,越稳定，动态性能越差。7.5常见张力控制问题7.5.1收卷张力、收卷椎度与薄膜宽度的关系？ 薄膜设备中采用张力自动控制，牵引张力和收卷张力是为了使薄膜正常牵引和收卷之需要，张力过小，不能在弓辊产生足够的力使膜展平而产生皱褶，张力过大，又会使薄膜被拉伸，（如果使用称重控制将产生实际厚度与显示厚度存在偏差的现象），造成薄膜质量下降。第二牵引的张力与表面收卷的张力的关系，如果第二牵引张力与表面收卷的张力关系调整不好时，会造成收卷部分拉伸或收缩（如果使用测宽设备将产生实际宽度与显示厚度存在偏差的现象）锥度控制的作用是当卷径增大时，逐渐衰减压臂的压力，使膜卷与表面辊之间的压力保持恒定。保证在收卷卷径增大时，薄膜成品宽度不减少。7.5.2第二牵引和收卷张力与锥度如何设定？第二牵引和收卷张力设定最小值以不产生薄膜皱褶为准，越小越好。当采用单边收卷时，第二牵引张力稍大于收卷张力。当采用双边收卷时，第二牵引张力稍大于内外收卷张力之和。 设定收卷臂压力时，大致上为1.0Mpa-2.0Mpa之间示情况而定。设定锥度时以收卷成品不产生（开始宽度宽、大卷径后宽度窄）的现象为最小值，但注意防止张力衰减到膜卷与表面辊之间无法产生足够的压力，造成收卷跑边等现象。7.6张力控制失常的常见故障、原因排除方法7.6.1张力控制器无法校零或校准 检查张力辊是否转动灵活。 检查张力传感器安装方向，ZC穿轴式张力传感器红点为合力方向。 校准负载没有按照膜路方向吊挂。 校准负载的膜路上有较大的其他负载，如部分机型的第二牵引，使标准砝码的无法准确的反应在张力辊上。 检查张力传感器电源电压，一般为12V。 检查张力传感器输入范围TR1、TR2是否正常，张力传感器信号输入范围为0-20mV，如果超出，则张力传感器损坏。 检查张力信号放大器或控制器电源灯是否点亮，如果张力传感器信号正常(TR1、TR2为0-20MV , TR1为负, TR2为正, TL1、TL2为0MV , VCC、GND为12V)，则张力信号放大器或控制器损坏，更换。7.6.2实际张力一直显示最大值或最小值0Kg 检查各变频器是否正常工作，输出是否正常。 检查线路是否正常。 检查张力辊及张力传感器轴承是否卡死。 检查膜路导辊是否运转灵活。 检查旋转牵引导辊运行是否正常，特别是如果导膜时太紧气垫辊将会引起二牵引张力波动或张力过大。 检查张力/速度模式是否在张力模式。 重复调校步骤1、2。 张力传感器损坏。 张力控制器损坏7.6.3张力波动比较大 检查薄膜是否在动力辊上是否有打滑现象。 检查二牵引夹棍是否夹紧力太小，间隙过大。 观察膜泡是否波动很大，膜泡波动大也容易造成张力波动大。 检查膜路及辊。 检查传动装置是否正常。 重复调校步骤1、2、3。 张力控制器高级调较。 张力控制器损坏或调乱，更换或重调。7.6.4张力一直存在偏差 检查薄膜是否在动力辊上是否有打滑现象。 重复调校步骤1、2、3。为保证电气系统控制的安全与可靠，电气控制柜必须定期检查各零部件的动作状态，接线的松紧情况，损坏的零件应及时更换。并经常进行除尘工作，保持清洁。定期检查各电机冷却风机，确保电机良好散热，机器周围如有干扰较大的用电设备应良好接地，减少干扰。另外，具体操作说明请阅读控制系统说明书。7. Tension Control and Faults7.1 Tension Control Theory and Technological ParametersTo achieve closed loop tension control, the tension control system of Jinming blown film winder is made up of tension sensor, tension signals amplifier and PLC.In the closed loop tension control, the tension sensor follows straining sheet electrical bridge measuring theory. It can be installed with an axis or on a base. It can measure the films exact power on the tension roller and output voltage signals in positive ratio with the power. ZC axis tension sensor and Mitsubishi base tension sensor are used in the blown film equipment. ZC axis tension sensor can indicate the directions of the powers. The red spot stands for the direction of resultant force. The technological parameters of ZC axis tension sensor are as follows: Voltage of power source: 612V，Output resistance: 350OhmSensitivity: 2mv/V，electrical connection 1、power source +，4、power source-，2、signal +，3、signal-，The other detailed technological parameters and details of Mitsubishi base tension sensor can be seen in the relevant instructions. Tension signals amplifier is used together with tension sensor, providing tension sensor with necessary calibration and zeroing voltage and outputting the signals of the sensor after it has amplified them. These signals achieve closed control through the PID controller, PLC control haul-off or winding inverter.The technological parameters of TAC100-020 and TAC100-020A: power source：24Vpower source of the tension sensor：12Vinput signals of tension sensor：20mVinput and output of the other control signals：0-10VThe other detailed technological parameters and use guides for TE-PC or LM-10TA can be seen in the relevant instructions.TAC100-020A wiring terminal definition （The blue boldfaces present control signals output, and the rest present signals input.）24V（+）、0V（-） input terminal of power sourceVCC（+）、GND（-） power source for tension sensor: 12VTR1（-）、TR2（+） for the signals input of tension sensor (right) 0-20mVTL1（-）、TL2（+） for the signals input of tension sensor (left)VO（+）、COM（-） real tension output: 0-10VA1（+）、A1（-）set tension: 0-10VA2（+）、A2（-）speed signals of the previous step (synchronous line speed): 0-10VAP（+）、COM（-） speed output of the control inverter: 0-10VZERO potentiometerzeroing SPAN potentiometercalibration R1 potentiometerrough adjustment of integral time 10-250SR2 potentiometer tiny adjustment of integral time 1-50SR3 potentiometer plus adjustmentR4 potentiometer synchronous signals adjustmentThe definitions and methods of specific connections of the other tension signal amplifiers or controllers can be seen in the relevant instructions. 7.2 Control ProposalsJinming equipment adopts the following two tension control proposals: A tension controller and TAC100-020A (tension signals amplification PID controller which is called tension controller for short) are used. The tension controller controls the inverter directly and meanwhile output the real tension to PLC to be displayed. PLC will output the tension setting into the tension controller. (adjustment steps 1, 2, 3)7.3 Tension AdjustmentTension adjustment steps:7.3.1 Synchronous line speed adjustments（only for TAC100-020A）Tension control is the tiny speed adjustment based on the line speed of the previous step. The adjustment of the synchronous line speed has an immediate influence on the accuracy of tension control. Customers do not need to do them because they have been finished in the factory. However, if the tension controller has been changed or tension control does not work after the haul-off and winding units (such as the inverter or gear box) have been changed, the adjustment should be repeated. The specific synchronous line speeds can be measured by instruments. They can also be got by looking at the inverters real frequencies when the tension is stable.Adjustment methods: Connect the terminal C2 to the terminal OV and remove the former linking line of C3 (or connect the linking line of C3 to C2 and turn PLC panel to the speed model). Start the first and the second haul-off units, the internal and the external winders and set the frequency of first haul-off to 25Hz. Adjust the potentiometer R4 to make the speeds of the second haul-off unit, the internal and external winders comply with that of the first haul-off unit. Recover the circuit. The adjustments have been finished.For example:The adjustment method for “measure the line speed with instrument”:Parts Before adjustmentAfter adjustmentReal line speedReal frequencyReal line speedReal frequencyThe 1st haul-off unit30m/min25HzThe 2nd haul-off unit33m/min25Hz30m/min22.7HzThe external winder36m/min25Hz30m/min20.8HzThe internal winder36m/min25Hz30m/min20.8Hz The adjustment method for “get the specific synchronous line speed by looking at frequency of each inverter when the tension is stable”:When the tension is stableBefore adjustmentAfter adjustmentReal line speed m/minReal frequency HzReal frequency HzReal frequency HzThe 1st haul-off unitunknown252525The 2nd haul-off unitunknown22.72522.7The external winderunknown20.82520.8The internal winder Unknown20.82520.8Figure 3.37.3.2 Zeroing and CalibrationTension sensors are precise elements. During their use and transportation, tiny distortion may be caused by the outside forces or because of their aging. Therefore, zeroing and calibration should be carried out periodically (suggestion: once every three months).Before the zeroing and calibration, the tension roller should be examined: Make sure whether the direction of the resultant force of the tension sensor is correct. Keep in mind that for ZC axis tension sensor, the red spot presents the direction of the resultant force.Make sure whether the tension roller can rotate agilely.Make sure whether the inserter is firm.Make sure whether short circuit or open circuit has happened to the linking lines of the tension signal amplifier or the controller.Method for the zeroing and calibration of TAC100: ZeroingWhen there is no power on the tension roller, adjust the potentiometer ZERO (moving clockwise means the increase of the output and moving anticlockwise means the decrease of the output). Test the output voltage of VO and COM with a voltmeter to make sure that the output voltage is zero. Look at the PLC operation interface to see whether the real tension is zero. CalibrationHang standard poises (5Kg) in the middle of the tension roller according the film track direction. Adjust the potentiometer SPAN (moving clockwise means the increase of the output and moving anticlockwise means the decrease of the output). Measure the output voltage of VO and COM with a voltmeter to see whether the output voltage comply with the requirements. Look at PLC operation interface to see whether the real tension is 5Kg.For instance:The max. tension of the sensor=30KgThe standard poises=5KgThe max. output voltage of VO and COM=10VThe voltage of the terminals VO and COM=the max. output voltage of VO and COM*the weight of the poises/the max. tension of the sensor（Kg）=10*5/30=1.67（V）Adjust the output voltage of VO and COM to 1.67V ExaminationThe purpose of this step is to certify whether the repeatability of the tension sensor is normal. First of all, when there is no power on the tension roller, examine the output voltage of VO and COM to see whether it is zero. Look at the PLC operation interface to see whether the real tension is zero. Then hang the standard poises 5kg and measure the output voltage of VO and COM with a voltmeter to see whether the output voltage complies with the requirements. Look at PLC operation interface to see whether the real tension is about 5kg. If the examination result is far different from the expectation, examine the tension roller to see whether it is normal and whether the poises have been hung correctly. And then calibrate again.Note: The examination methods for the other models can be found in the instructions.7.3.3 Test The purpose of the test is to prepare for normal production by examining the 1,2 step adjustments to make sure whether the tension controller is normal. Start the first and the second haul-off units, the internal and the external winders and set the first haul-off unit to 25Hz. Set to the tension model on PLC operation interface. Set the tension of the second haul-off unit to 5kg (the real tension at this moment is 0kg). Without a load on the second haul-off unit, observe it to see whether its real speed is about 3Hz higher than the synchronous speed. Lay an outside force of over 5kg on the tension roller of the second haul-off unit (the outside force can be produced by press a finger on the tension in the expected direction). When the second haul-off unit is descending at a slow speed, observe and make sure whether the real speed of the second haul-off unit is about 3Hz higher than the synchronous speed. Take the testing of the second haul-off unit for reference for the tension testing of the internal and the external winders. The tension examination and testing are finished.For example, the synchronous speed can be got by the first adjustment method, see figure 3.4Synchronous speedNo-load LoadReal frequency HzReal frequency HzReal frequency HzThe 1st haul-off unit252525The 2nd haul-off unit22.7About 25.7 About 19.7 Figure 3.47.4 Senior Adjustment of the Tension ControllerThe senior adjustment of the tension controller is usually carried out on line. It has been finished at the factory and is usually unnecessary to do it when it is used in the customers workshop. When the tension control is out of gear, examine the tension sensor and the film track at first to make sure whether they are normal. If the problem can not be solved after all the other faults have been removed, the adjustment should be carried out by an appointed person. During the adjustment, attention should be paid to the parameters before the adjustment so as to prevent the control from getting worse. Before the adjustment, the following 1,2 steps should be taken.The tension stability should be adjusted at first and then the tension tolerance.The tension stability is indicated by the tension fluctuation.The tension tolerance means the difference between the real tension and the set tension. The tension is stable, but for a long time, it is not the same as the setting.Adjustment method:Adjust the controllers R1, R2 and R3. If the tension fluctuates in a wide range, adjust R2 anticlockwise at first and then adjust R1 anticlockwise. If the tension still fluctuates in a wide range at this moment, adjust R3 until the tension become stable.If the tension tolerance has not been well adjusted, repeat the above step 1.R1 Rough adjustment of time. When it is adjusted clockwise, the number will become bigger and it will become more sensitive. However, tension librations may be caused.R2 Tiny adjustment of time. When it is adjusted clockwise, the number will become bigger and it will become more sensitive. However, tension librations may be caused. R3 Plus adjustment. When it is adjusted clockwise, the number will become bigger and it will become more sensitive. When it is adjusted anticlockwise, the number will become smaller and it will become more stable and is of worse dynamic performance. 7.5 Common Tension Control Problem7.5.1 The Relation among Winding Tension, Winding Conicity and Film WidthThe tensions are controlled automatically. The haul-off tension and winding tension ensure the normal haul-off and winding. If the tensions are too weak, inadequate power on the bow, which serves to flat the film will be produced and rumples will appear on the film. If the tension is too strong, the film will be stretched and its quality will become worse. (If a gravimetric unit is used, the difference between the real thickness and the displayed thickness will appear.) If the relation between the tensions of the second haul-off unit and surface winder is not well adjusted, the film will be stretched or shrink. (If a width measuring unit is used, the difference between the real width and the displayed width will appear.)Conicity control plays a role to decrease the pressure of the press arm when the film roll is becoming bigger so that the pressure between the film roll and the surface roller is kept constant. It ensures that the width of the finished film does not decrease when the film roll becomes bigger.7.5.2 How to Set the Tensions of the Second Haul-off Unit and the Winder and the