First, the solution of Franck frequency converter in the injection molding machine
Hydraulic injection molding machines have vertical and horizontal types.
1.1 Vertical Injection Molding Machine Solutions
Dozens of grams of vertical injection molding machine, oil pump uses a gear pump, the motor capacity is also smaller, electrical control circuit is also relatively simple. When installing, the inverter for injection molding machine is directly connected to the power supply circuit of the motor, and then the signal of the flow proportional valve (0 to 1A) is converted into a 4 to 20 mA signal and sent to the corresponding port of the inverter. As the process changes, the flow of hydraulic oil also changes. Generally speaking, it is better to take the flow signal with a relatively large change of relative value as the control signal, and the change of the control signal has a larger range of frequency adjustment of the frequency converter; and the relative value of the pressure signal changes less, and the frequency adjustment range of the frequency converter is smaller. . If the inverter frequency adjustment range does not meet the process requirements, you can use the frequency converter's function "frequency gain" to adjust. Injection molding machine dedicated frequency converter is based on the general inverter has added a 0 ~ 1A signal conversion link, it is more convenient to use.
1.2 Horizontal Injection Molding Machine Solutions
More than 60 grams are horizontal injection molding machines, 60 grams to 500 grams of injection molding machines, some are oil pumps, and some are two oil pumps. The process of installing an injection molding machine-dedicated inverter in an oil pump injection molding machine is the same as that of a vertical injection molding machine: the signal of 0 to 1A is still taken out from the flow proportional valve as the speed adjustment signal of the inverter, although the speed adjustment signal It is feedbacked by the hydraulic circuit element to the frequency converter, but there is no given signal in the control loop, so the control still belongs to the open-loop control mode. It is also because of energy-saving reasons that large and medium injection molding machines may have more than one oil pump. For example, Mitsubishi 850-MM, 1300-MM, 1800-MM, 2000-MM injection molding machines all have three oil pumps. Corresponding to the injection molding process, the required system pressure is low during the mold closing phase. Only the #1 oil pump works. When the system pressure required for the mold clamping phase is high, the #2 oil pump is put into operation again. The highest pressure is required. Three oil pumps are put into operation at the same time. The pressure required for demoulding and opening molds is low, and then the 3# and 2# oil pumps are stopped respectively. As long as the boot, 1 # pump has been running. Using three small oil pumps to work intermittently at different stages of the process requires energy savings compared to using a large pump.
How to transform an injection molding machine with two or more oil pumps? Here is an example of the modification of the Mitsubishi 1800-MM injection molding machine. Mitsubishi 1800-MM injection molding machine has three 45KW oil pump motors. One inverter drives 1# oil pump motor. The adjustment signal of the frequency converter is taken from the injection molding machine flow proportional valve. In this way, the frequency of this frequency converter is related to the hydraulic oil of the injection molding machine. The flow changes and changes. The other two pump motors can be driven by two inverters. However, these two inverters do not perform speed control on the motor and only perform two-phase control, ie start and stop. Control start and stop signals of the frequency converter are taken from the start and stop signals of the original oil pump motor. The upper limit frequency of the inverter is set below 50Hz. The specific setting value is related to the workpiece size, material, barrel temperature and other factors. If the frequency converter operates below 50Hz, it can save energy. In fact, there are margins in the design of the injection molding machine, and the oil pressure required to change the size of the workpiece and the material changes. If the injection pressure is too large and the clamping force is insufficient, the workpiece will be flashed; if the injection force is insufficient, the plastic in the mold cavity will be less than full, the workpiece will be scrapped; when the pressure is insufficient, the plastic in the workpiece will shrink when the plastic is thick .
Second, install injection molding machine-specific inverter precautions
2.1 Selection of Inverter for Injection Molding Machine
Injection molding machine load properties are constant torque, mechanical properties are hard, dynamic requirements are high, so you should use high-performance vector control inverter. The general V/F control converter is difficult to meet the requirements of quick response. Injection molding machine frequency converter is based on general-purpose frequency converter based on an increase of 0 ~ 1A signal conversion link, improve the use of performance.
Considering that there are certain requirements for the injection molding process at each stage, the accelerating and decelerating time of the inverter should be short, generally 1 second. The capacity selection of the inverter must be based on the actual situation. Therefore, before selecting the capacity of the inverter, the maximum load current of the pump motor in the power frequency state of the injection molding machine should be measured during the various process steps of the injection molding machine as a basis for selecting the capacity of the inverter. The rated current of the inverter is preferably 1.1 to 1.5 times the rated current of the motor, and the voltage level should be in accordance with the control motor. This may require the inverter capacity to be increased by one-stage selection.
2.2 to have a backup system
Injection molding machine installed after injection molding machine-specific frequency converter, should be the frequency of the starting circuit as a backup, so that once the injection molding machine-specific inverter fault, but also with the frequency of starting the pump motor to continue to run, to reduce the injection molding machine-specific The economic loss caused by the inverter failure.
2.3 Injection molding machine frequency converter signal extraction point
Take the flow signal of the double proportional valve (0~1A) and convert it into 4~20m signal to the corresponding port of the inverter. The flow signal takes a relatively large value as a control signal to expand the adjustment range. The relative change of the pressure signal is small, and the adjustment range of the inverter frequency is smaller. If the adjustment range of the inverter can not meet the needs of the forming process, you can use the frequency gain function of the inverter to adjust.
2.4 Pre-commissioning Precautions
Installation of injection molding machine type inverter is relatively simple, but before the transformation should be a detailed understanding of the injection molding machine working conditions, familiar with the injection molding machine process, debugging should pay attention to the following matters: Carefully observe the injection molding machine frequency operation is normal, whether the pump motor is often Overload state; according to the injection molding machine mold and injection molding process to observe the potential of injection molding machine power saving transformation; control signal line should pay attention to the positive and negative polarity should not be reversed; signal line and the main circuit line to separate wiring.
2.5 Interference of Digital Inverter Used in Injection Molding Machine
Now widely used on injection molding machines is AC-DC-AC frequency converters, whose output current contains harmonic components, which may cause interference to the injection molding machine. The most susceptible to interference is the temperature control instrument. Therefore, the installation of the frequency converter should be done well. Anti-jamming measures. Inverter shall be equipped with input and output reactors or high-frequency magnetic rings, etc.; control lines introduced into the inverter shall be shielded; the chassis shall be reliably grounded; do not make the input and output cables of the inverter parallel to the control signal lines of the inverter. Or bundled together; when the inverter is installed inside the injection molding machine, pay special attention to ventilation and heat dissipation.
Third, debugging common problems and processing methods
Due to the particularity of the injection molding machine process, various faults will be encountered in the process of installing the special inverter for the injection molding machine. The following are the problems encountered in the process of installing the frequency conversion of the injection molding machine and the treatment methods.
3.1 No change in the frequency of injection molding machine type inverter
Because the inverter adopts the valve-controlled current signal of the injection molding machine to adjust the speed, the frequency of the inverter is displayed as 0.0 (some inverters show 0). The main reason is that the signal polarity is reversed; the signal is wrong; the signal wiring The port is inconsistent with the parameter setting; the auxiliary power supply failure of the injection molding machine, etc. This type of failure should be checked first. The category of valve control of the injection molding machine is the current signal, voltage signal or pulse control signal (some models), and the positive and negative polarity of the signal. Does it correspond to the inverter control terminal?
3.2 The noise of the oil pump
After the injection molding machine type inverter runs, some injection molding machines issue abnormal noises. At this time, the source of the noise should be judged whether it is from the motor or the oil pump. If the noise of the pump is due to the following reasons: the injection molding machine has too little hydraulic oil. Air inhalation; Injection molding machine oil filter or oil obstruction; Injection pump oil pump blade wear more serious; In case of circumstances should first check the injection pump oil pump, troubleshooting before running, and when the injection is in the low speed and high pressure working conditions, Abnormal oil pump noise occurs. At this time, the speed signal is appropriately increased.
Fourth, Franke inverter for injection molding machine circuit diagram
V. Technical Advantages of Francois Inverter in Injection Molding Machine Industry
5.1 The Francis frequency converter is a current vector control method with large starting torque, 0.5 Hz can reach 150% of the rated torque; fast dynamic response, step torque response time < 200 ms; steady speed accuracy of 0.5%. The fast dynamic response effectively solves the chronic problems that have plagued the injection molding industry with inverters with longer post-processing cycles.
5.2 The unique torque control performance of the Franck frequency converter effectively controls the overcurrent without affecting the momentary moment, avoiding the frequent protection of the frequency converter or the phenomenon of high current burning out of the frequency converter, providing confidence to the supporting manufacturers. .
5.3 The corresponding relationship between the analog input and the frequency of the FRB6000 series inverter can be set as a fold line type, and two inflection points can be set to facilitate the strong pressure required when clamping. At the same time, the vector inverter's control characteristics enable the load current to be effectively controlled. This is aimed at the special machine design of the injection molding machine industry, effectively avoiding the common fault of over-current protection of conventional inverters.
5.4 Through the external terminal block, can receive 0~1A electric current signal directly, can obtain the rotational speed control signal directly from the proportional flow valve.
5.5 can accept 0 ~ 1A current signal and 0 ~ 10V voltage signal, some of the injection molding machine process section of the acquisition signal compensation, to achieve a perfect control effect.
Hydraulic injection molding machines have vertical and horizontal types.
1.1 Vertical Injection Molding Machine Solutions
Dozens of grams of vertical injection molding machine, oil pump uses a gear pump, the motor capacity is also smaller, electrical control circuit is also relatively simple. When installing, the inverter for injection molding machine is directly connected to the power supply circuit of the motor, and then the signal of the flow proportional valve (0 to 1A) is converted into a 4 to 20 mA signal and sent to the corresponding port of the inverter. As the process changes, the flow of hydraulic oil also changes. Generally speaking, it is better to take the flow signal with a relatively large change of relative value as the control signal, and the change of the control signal has a larger range of frequency adjustment of the frequency converter; and the relative value of the pressure signal changes less, and the frequency adjustment range of the frequency converter is smaller. . If the inverter frequency adjustment range does not meet the process requirements, you can use the frequency converter's function "frequency gain" to adjust. Injection molding machine dedicated frequency converter is based on the general inverter has added a 0 ~ 1A signal conversion link, it is more convenient to use.
1.2 Horizontal Injection Molding Machine Solutions
More than 60 grams are horizontal injection molding machines, 60 grams to 500 grams of injection molding machines, some are oil pumps, and some are two oil pumps. The process of installing an injection molding machine-dedicated inverter in an oil pump injection molding machine is the same as that of a vertical injection molding machine: the signal of 0 to 1A is still taken out from the flow proportional valve as the speed adjustment signal of the inverter, although the speed adjustment signal It is feedbacked by the hydraulic circuit element to the frequency converter, but there is no given signal in the control loop, so the control still belongs to the open-loop control mode. It is also because of energy-saving reasons that large and medium injection molding machines may have more than one oil pump. For example, Mitsubishi 850-MM, 1300-MM, 1800-MM, 2000-MM injection molding machines all have three oil pumps. Corresponding to the injection molding process, the required system pressure is low during the mold closing phase. Only the #1 oil pump works. When the system pressure required for the mold clamping phase is high, the #2 oil pump is put into operation again. The highest pressure is required. Three oil pumps are put into operation at the same time. The pressure required for demoulding and opening molds is low, and then the 3# and 2# oil pumps are stopped respectively. As long as the boot, 1 # pump has been running. Using three small oil pumps to work intermittently at different stages of the process requires energy savings compared to using a large pump.
How to transform an injection molding machine with two or more oil pumps? Here is an example of the modification of the Mitsubishi 1800-MM injection molding machine. Mitsubishi 1800-MM injection molding machine has three 45KW oil pump motors. One inverter drives 1# oil pump motor. The adjustment signal of the frequency converter is taken from the injection molding machine flow proportional valve. In this way, the frequency of this frequency converter is related to the hydraulic oil of the injection molding machine. The flow changes and changes. The other two pump motors can be driven by two inverters. However, these two inverters do not perform speed control on the motor and only perform two-phase control, ie start and stop. Control start and stop signals of the frequency converter are taken from the start and stop signals of the original oil pump motor. The upper limit frequency of the inverter is set below 50Hz. The specific setting value is related to the workpiece size, material, barrel temperature and other factors. If the frequency converter operates below 50Hz, it can save energy. In fact, there are margins in the design of the injection molding machine, and the oil pressure required to change the size of the workpiece and the material changes. If the injection pressure is too large and the clamping force is insufficient, the workpiece will be flashed; if the injection force is insufficient, the plastic in the mold cavity will be less than full, the workpiece will be scrapped; when the pressure is insufficient, the plastic in the workpiece will shrink when the plastic is thick .
Second, install injection molding machine-specific inverter precautions
2.1 Selection of Inverter for Injection Molding Machine
Injection molding machine load properties are constant torque, mechanical properties are hard, dynamic requirements are high, so you should use high-performance vector control inverter. The general V/F control converter is difficult to meet the requirements of quick response. Injection molding machine frequency converter is based on general-purpose frequency converter based on an increase of 0 ~ 1A signal conversion link, improve the use of performance.
Considering that there are certain requirements for the injection molding process at each stage, the accelerating and decelerating time of the inverter should be short, generally 1 second. The capacity selection of the inverter must be based on the actual situation. Therefore, before selecting the capacity of the inverter, the maximum load current of the pump motor in the power frequency state of the injection molding machine should be measured during the various process steps of the injection molding machine as a basis for selecting the capacity of the inverter. The rated current of the inverter is preferably 1.1 to 1.5 times the rated current of the motor, and the voltage level should be in accordance with the control motor. This may require the inverter capacity to be increased by one-stage selection.
2.2 to have a backup system
Injection molding machine installed after injection molding machine-specific frequency converter, should be the frequency of the starting circuit as a backup, so that once the injection molding machine-specific inverter fault, but also with the frequency of starting the pump motor to continue to run, to reduce the injection molding machine-specific The economic loss caused by the inverter failure.
2.3 Injection molding machine frequency converter signal extraction point
Take the flow signal of the double proportional valve (0~1A) and convert it into 4~20m signal to the corresponding port of the inverter. The flow signal takes a relatively large value as a control signal to expand the adjustment range. The relative change of the pressure signal is small, and the adjustment range of the inverter frequency is smaller. If the adjustment range of the inverter can not meet the needs of the forming process, you can use the frequency gain function of the inverter to adjust.
2.4 Pre-commissioning Precautions
Installation of injection molding machine type inverter is relatively simple, but before the transformation should be a detailed understanding of the injection molding machine working conditions, familiar with the injection molding machine process, debugging should pay attention to the following matters: Carefully observe the injection molding machine frequency operation is normal, whether the pump motor is often Overload state; according to the injection molding machine mold and injection molding process to observe the potential of injection molding machine power saving transformation; control signal line should pay attention to the positive and negative polarity should not be reversed; signal line and the main circuit line to separate wiring.
2.5 Interference of Digital Inverter Used in Injection Molding Machine
Now widely used on injection molding machines is AC-DC-AC frequency converters, whose output current contains harmonic components, which may cause interference to the injection molding machine. The most susceptible to interference is the temperature control instrument. Therefore, the installation of the frequency converter should be done well. Anti-jamming measures. Inverter shall be equipped with input and output reactors or high-frequency magnetic rings, etc.; control lines introduced into the inverter shall be shielded; the chassis shall be reliably grounded; do not make the input and output cables of the inverter parallel to the control signal lines of the inverter. Or bundled together; when the inverter is installed inside the injection molding machine, pay special attention to ventilation and heat dissipation.
Third, debugging common problems and processing methods
Due to the particularity of the injection molding machine process, various faults will be encountered in the process of installing the special inverter for the injection molding machine. The following are the problems encountered in the process of installing the frequency conversion of the injection molding machine and the treatment methods.
3.1 No change in the frequency of injection molding machine type inverter
Because the inverter adopts the valve-controlled current signal of the injection molding machine to adjust the speed, the frequency of the inverter is displayed as 0.0 (some inverters show 0). The main reason is that the signal polarity is reversed; the signal is wrong; the signal wiring The port is inconsistent with the parameter setting; the auxiliary power supply failure of the injection molding machine, etc. This type of failure should be checked first. The category of valve control of the injection molding machine is the current signal, voltage signal or pulse control signal (some models), and the positive and negative polarity of the signal. Does it correspond to the inverter control terminal?
3.2 The noise of the oil pump
After the injection molding machine type inverter runs, some injection molding machines issue abnormal noises. At this time, the source of the noise should be judged whether it is from the motor or the oil pump. If the noise of the pump is due to the following reasons: the injection molding machine has too little hydraulic oil. Air inhalation; Injection molding machine oil filter or oil obstruction; Injection pump oil pump blade wear more serious; In case of circumstances should first check the injection pump oil pump, troubleshooting before running, and when the injection is in the low speed and high pressure working conditions, Abnormal oil pump noise occurs. At this time, the speed signal is appropriately increased.
Fourth, Franke inverter for injection molding machine circuit diagram
V. Technical Advantages of Francois Inverter in Injection Molding Machine Industry
5.1 The Francis frequency converter is a current vector control method with large starting torque, 0.5 Hz can reach 150% of the rated torque; fast dynamic response, step torque response time < 200 ms; steady speed accuracy of 0.5%. The fast dynamic response effectively solves the chronic problems that have plagued the injection molding industry with inverters with longer post-processing cycles.
5.2 The unique torque control performance of the Franck frequency converter effectively controls the overcurrent without affecting the momentary moment, avoiding the frequent protection of the frequency converter or the phenomenon of high current burning out of the frequency converter, providing confidence to the supporting manufacturers. .
5.3 The corresponding relationship between the analog input and the frequency of the FRB6000 series inverter can be set as a fold line type, and two inflection points can be set to facilitate the strong pressure required when clamping. At the same time, the vector inverter's control characteristics enable the load current to be effectively controlled. This is aimed at the special machine design of the injection molding machine industry, effectively avoiding the common fault of over-current protection of conventional inverters.
5.4 Through the external terminal block, can receive 0~1A electric current signal directly, can obtain the rotational speed control signal directly from the proportional flow valve.
5.5 can accept 0 ~ 1A current signal and 0 ~ 10V voltage signal, some of the injection molding machine process section of the acquisition signal compensation, to achieve a perfect control effect.