Frequency energy-saving injection molding machine (2)

Date：2014/1/25 16:39:58

3 quantitative pump injection molding machine frequency transformation program
        When quantitative pump injection molding machine frequency transformation , in order to ensure that the transformation will not have any impact on production , try not original injection molding machine hydraulic system and electrical control system for change. Inverter control is the use of injection molding machine control system synchronization control signal , the controller regulates the flow given the injection molding machine , analog signal proportional pressure valve ( eg 0 - 1ADC), treated transform into a 0 - 10VDC or 4 ~ 20 mA signal to the inverter, used to adjust the pump motor speed. Each step required in this section can make the output of the hydraulic system of the injection molding machine and the size of the hydraulic flow rate of an exact match, so that the relief valve to minimize back-flow , to save energy. At present, the inverter control part of the treatment of proportion and flow proportional pressure from the injection molding machine controller control signal varied. Most directly to one of the signal conversion through the circuit board to convert analog converter available ; product flow and pressure signals some sucked through the operation , the inverter converts the amplified signals available ; also some in order to achieve better control effect , according to the process and product characteristics of injection molding machine specially set up corresponding mathematical model , and then use the injection molding machine controller sends pressure, flow control signal corresponding to the amount calculated to control the output frequency . In addition , in order to strengthen the reliability of the system , retaining the original dosing pump motor frequency operation circuit , and increase the control circuit to ensure that users can easily run frequency and frequency of switching. When the drive fails, the pump motor is switched to the manual that corresponds to the original operating mode ( frequency operation ) , the other part is still driven by the inverter , is not affected.
        As can be seen , the system uses an inverter to drive a motor works, the inverter can output an alarm signal indicating a fault . When a drive fault , you can switch to the original frequency mode via control buttons. Inter- frequency mode of the inverter and electrical interlocks to ensure frequency operation and frequency operation will not start simultaneously.
        4 examples of energy-saving injection molding machine frequency
        Drive injection molding machine with a vector control , with high-speed dynamic response and excellent automatic current limiting capability , and instant overload up to 200 % of rated load , and the other at zero frequency mode without speed sensor can output 150% rated torque . These features meet the application requirements of injection molding machines , injection molding machines coupled with TD3400 drive features a special injection molding machine according to the application adds the corresponding function , so in the injection molding industry has been widely used.
        Currently , TD3400 inverter has been successfully applied in a variety of brands of injection molding machines, and several companies successfully injection molding machine for the transformation of large quantities of energy saving effect is very good. In this paper, a plastic products manufacturer to make the results of energy-saving injection molding machines , for example, the test data to illustrate the quantitative pump injection molding machine frequency transformation of energy savings. The transformation of a model EA80 effect of the injection molding machine to do the test . The device pump motor power 11kW, producing products for Acrylic transparent , mold model used is KEMP2755B, both before and after the transformation requirements of the production cycle is 26 seconds / beer , that beer production was 138 / hour meter is used to test phase four-wire meter .
        5 Renovation common problems and solutions
        Production cycle approach may be extended to solve 5.1
        At the time of the injection molding machine frequency transformation, may often find that the production cycle will be slower when working frequency 0.3 - 1.2 seconds . And the drive power , the more complex the product condition , the cycle will rise correspondingly .
        This is mainly due to the different processes segment switch , the drive requires each process depending on the required pressure , flow and changing the output frequency , leaving the motor always in the process of acceleration and deceleration . Although the inverter deceleration time adjustable very short , but compared to frequency operation speed solenoid valve off a certain lag , which led to the unit when the processing cycle has been extended under the same process parameters frequency control , production efficiency affected. For this problem, on the one hand , requires optional drive has good dynamic response performance to minimize response time ; on the other hand , according to the actual situation, adjust the injection molding machine part of the process parameters, such as increased pressure setting and so on. Of course , you can also control the hydraulic system and improve the system to solve the problem . Such as injection molding machine hydraulic system designed with hydraulic shock harm in hydraulic circuit uses a lot of power frequency when the buffer circuit . If we can improve the hydraulic circuit reaction time can make up for the lag caused by frequency acceleration . As for the inverter control system , if they can control the use of two-way signal flow and pressure , but also better able to solve this problem.
        5.2 pressure is not enough reason and corresponding measures
        Individual cases, due to the quality of the components used in the machine , but off , or poor maintenance , the individual hydraulic circuit hydraulic components wear, leading to their decline in pressure --- flow characteristics , resulting in greater pressure versus the control flow . At this exhibit enough force sometimes and sometimes not enough power phenomenon. Due to the constant flow produced frequency , so the problem is not exposed.
        When using frequency control will show pressure is not enough . To solve this problem , one way is by adjusting the process parameters of the injection molding machine , the flow of the pressure molding machine working frequency is set higher than the number of the frequency . Another way is to think of a way from the control methods, such as pressure -based closed-loop control of speed link , ensure that the pressure to meet the requirements .
        5.3 inverter response to the injection molding machine interference
        Since the inverter input at work, the output current will have a certain amount of high harmonics, injection molding machine control system would cause interference , severe cases may affect the normal operation of the injection molding machine .
        In this regard , you can take the following measures:
        ① input side and the output side of the installation drive special filters , reactors , etc. to reduce the high harmonic currents ;
        ② control signal lines use shielded cables and inverter connected to one end of the shield public input terminal ;
        Input and output cables and inverter control signal line ③ go separate lines, should ensure that the distance between them is at least 20cm above and as far as possible ;
        ④ reduce the carrier frequency of the inverter ;
        ⑤ other equipment under the same power supply isolation is best able to do .
        Comprehensive benefits 6 quantitative pump injection molding machine frequency transformation
        ( 1 ) quantitative pump into energy-saving variable pump , making the necessary power to match the injection molding machine hydraulic system and the machine runs , no high-pressure throttling overflow energy loss , saving up to 25 % to 60 %.
        ( 2 ) Due to the frequency converter can adjust the pump flow and pressure , so that the oil will reduce the frequency of 15 than under the state - 18 ℃. Reducing unnecessary heat loss , the amount of cooling water can also save more than 30%.
        ( 3 ) The power factor of 0.6 - 0.8 up to 0.96 or more, greatly reducing the reactive current , reducing line losses , improve power quality and power efficiency. Power supply equipment, equivalent to the role played Capacity .
        ( 4 ) through the inverter to achieve a soft start the motor, to avoid the impact on the starting grid , so no need to re- supply equipment aside additional capacity to cope with the impact of motor starting on the grid , the increase in the installed system capacity.
        ( 5 ) can be achieved using a converter soft start motor to ensure a smooth start without impact . One can reduce the impact of the starting motor to protect the motor , extending its service life ; the other hand, reducing the opening , locking the impact , and to extend the life of the mold machinery , thereby reducing the noise.
        ( 6 ) frequency operation pressure oil temperature can be reduced to 35 - about 40 ℃, oil under the best of this situation to ensure the accuracy and stability of the hydraulic actuator assembly , and can make the life of the seal assembly is extended, reducing maintenance downtime the frequency and repair time , save a lot of maintenance costs.
        ( 7 ) After using the drive , it has overvoltage , overcurrent , overload , overheating , undervoltage and short to ground and other protection , capable of on-line monitoring , to detect faults and alarms. You can protect the drive itself ; able to protect the motor ; avoid injection molding machine parts damaged due to incorrect handling . Reliability of the system is greatly improved.
        ( 8 ) because the injection molding machine to retain the original control mode and the oil change, can achieve frequency / frequency switching , even when the drive failure can also be converted to a frequency state , will not affect production.

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