A servo positioning control method for a molding machine control system

Abstract

The invention relates to a servo positioning control method for a molding machine control system. In the process of the servo motor executing a positioning instruction, the method makes a real-time judgment on the actual torque of the servo motor. When the actual torque exceeds a set torque threshold, the operation of the entire molding machine will not be stopped immediately, but the duration of the actual torque exceeding the torque threshold will be calculated to form a torque buffer period, so that the positioning instruction or the operation of other components can have time to continue to be executed. Only when the actual torque exceeds the limit time specified by the torque threshold, the current positioning instruction will be cleared and a forced stop instruction will be issued to the servo controller, forcing the servo motor to stop and issue an alarm message, and an interrupt request will not be directly issued once the torque threshold is exceeded, triggering an alarm and stopping the operation of the entire molding machine, thereby reducing the frequency of the molding machine alarm shutdown and maintenance restart, extending the effective operation time of the molding machine, and reducing the shutdown loss of the molding machine.

Description

Technical Field

[0001] The present invention relates to the technical field of molding machines, and in particular to a servo positioning control method of a molding machine control system. Background Art

[0002] At present, most of the servo motors used to drive the multi-station molding machine mold table are controlled by PLC programming. The positioning instructions are written in the PLC in advance, and the servo motor is positioned according to the positioning instructions. However, in order to prevent the actual torque value of the molding machine mold table from increasing with continuous operation during automatic operation, a torque protection threshold is set for the molding machine in actual operation. Once the protection threshold is exceeded, an interrupt request is directly issued, triggering an alarm and stopping the operation of the entire molding machine. Workers are required to deal with the torque problem before restarting the molding machine to operate again, resulting in frequent start and stop of the molding machine, which seriously affects the service life of the molding machine. Summary of the invention

[0003] The problem to be solved by the present invention is to provide a servo positioning control method for a molding machine control system, which can more safely control the alarm of the servo motor, reduce the start and stop frequency of the molding machine, and reduce the shutdown loss of the molding machine. The technical solution adopted is as follows:

[0004] A servo positioning control method for a molding machine control system, characterized by comprising the following steps:

[0005] (1) Set up a positioning instruction trigger subroutine and a torque protection subroutine in the PLC, where the positioning instruction trigger subroutine includes the following steps:

[0006] (1-1-1) Set the trigger conditions for sending positioning instructions;

[0007] (1-1-2) receiving a control signal from a control system of the molding machine;

[0008] (1-1-3) Determine whether the control signal meets the trigger condition. If the trigger condition is met, the PLC sends a positioning command to the servo controller to control the servo motor to perform the corresponding positioning action, and then executes the torque protection subroutine;

[0009] The torque protection subroutine includes the following steps:

[0010] (1-2-1) Set the torque threshold and the time limit for exceeding the torque threshold;

[0011] (1-2-2) Receive the actual torque of the servo motor fed back by the servo controller, compare the actual torque with the torque threshold, and when the actual torque is greater than and lasts for longer than the limit time, clear the current positioning command and send a forced stop command to the servo controller, forcing the servo motor to stop, and send an alarm message;

[0012] (2) Execute the positioning instruction to trigger the subroutine;

[0013] (3) Determine whether the current positioning instruction has been executed. If it has been completed, clear the current positioning instruction and return to step (2).

[0014] The control system of the molding machine configures the servo motor hardware in the PLC program, writes motion instructions, and performs communication control through the communication system and the hardware's own integrated communication protocol.

[0015] The positioning instruction is sent from the molding machine's control system to the servo motor. The positioning instruction contains the triggering conditions of the positioning instruction and the control method of the servo motor. The control method includes but is not limited to the position control method, displacement command, speed command and other variable assignments. The servo motor is closed-loop positioned through the torque loop, speed loop and position loop control system in the servo controller. After the worker presets the molding machine, when the molding machine's control system sends a control signal, it determines whether the control signal meets the triggering conditions of the positioning instruction.

[0016] In the process of the servo motor executing the positioning instruction, the actual torque of the servo motor is judged in real time. When the actual torque exceeds the set torque threshold, the operation of the entire molding machine will not be stopped immediately, but the duration of the actual torque exceeding the torque threshold will be calculated to form a torque buffer period, which allows time for the positioning instruction or the operation of other components to continue to be executed; until the actual torque exceeds the limit time specified by the torque threshold, the current positioning instruction will be cleared and a forced stop instruction will be issued to the servo controller, forcing the servo motor to stop and issue an alarm message, instead of directly issuing an interrupt request as soon as the torque threshold is exceeded, triggering an alarm and stopping the operation of the entire molding machine, thereby reducing the frequency of the molding machine's alarm shutdown and maintenance restart, extending the effective operating time of the molding machine, and reducing the molding machine's downtime loss.

[0017] As a preferred embodiment of the present invention, the trigger condition in the step (1-1-1) is a trigger signal, the control signal in the step (1-1-2) is a production parameter preset by the molding machine control system, and the step (1-1-3) determines whether the control signal satisfies the trigger condition by converting the production parameter into a trigger signal, and when the trigger signal is triggered, it is determined that the trigger condition is satisfied.

[0018] As a further preferred embodiment of the present invention, the trigger signal in step (1-1-1) is a time pulse signal, and the step (1-1-3) of judging whether the control signal satisfies the trigger condition is specifically as follows: the production parameter is converted into a time pulse signal, and when the time pulse signal is triggered, it is judged that the trigger condition is met.

[0019] Usually, workers will set the production module on the interactive interface of the molding machine as the trigger condition for the positioning instruction. When the control system of the molding machine receives the trigger condition, it generates a time pulse signal. When the pulse signal is triggered, it is deemed that the trigger condition for the positioning instruction is met. The control system of the molding machine sends the corresponding positioning instruction to the servo motor, causing the servo motor to perform the corresponding action.

[0020] As a further preferred solution of the present invention, the production parameters are preset on the human-machine interaction interface of the molding machine control system. The production parameters are set on the interactive interface of the molding machine as the triggering condition of the positioning instruction, based on the ModbusTCP communication protocol integrated by the touch screen and the PLC, and data is read and written to each other through the Ethernet physical communication method.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] The present invention combines the positioning command control and torque protection control of the servo motor of the molding machine. In the process of the servo motor executing the positioning command, the actual torque of the servo motor is judged in real time. When the actual torque exceeds the torque threshold, the operation of the entire molding machine will not be stopped immediately. Instead, the duration of the actual torque exceeding the torque threshold is calculated to form a torque buffer period, which allows time for the positioning command or other components to continue to be executed, reduces the frequency of the molding machine's alarm shutdown and maintenance restart, prolongs the effective operation time of the molding machine, and reduces the shutdown loss of the molding machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0024] The following is a further description of the preferred embodiments of the present invention in conjunction with the accompanying drawings.

[0025] like Figure 1 As shown, a servo positioning control method of a molding machine control system comprises the following steps:

[0026] S1: Setting a positioning instruction trigger subroutine and a torque protection subroutine in the PLC; wherein the positioning instruction trigger subroutine includes the following steps:

[0027] S1-1-1: Set the trigger condition for sending positioning instructions. The trigger condition is a time pulse signal.

[0028] S1-1-2: Receive the control signal from the forming machine control system. The control signal is the production parameters preset by the forming machine control system, and the production parameters are preset on the human-machine interface of the forming machine control system.

[0029] S1-1-3: Convert the production parameters into time pulse signals, and determine whether the control signal meets the time pulse signal. When the time pulse signal is triggered, it is determined that the trigger condition is met; if the trigger condition is met, the PLC issues a positioning command to the servo controller to control the servo motor to perform the corresponding positioning action, and then execute the torque protection subroutine; if not, the servo controller remains standby and waits for the next control signal.

[0030] The torque protection subroutine includes the following steps:

[0031] S1-2-1: Set the torque threshold and the limit time for exceeding the torque threshold.

[0032] S1-2-2: Receive the actual torque of the servo motor feedback by the servo controller, compare the actual torque with the torque threshold. When the actual torque is greater than and the duration exceeds the limit time, clear the current positioning command and issue a forced stop command to the servo controller to force the servo motor to stop, and send an alarm message.

[0033] S2: Execute the positioning command trigger subroutine.

[0034] S3: Determine whether the current positioning command has been completed. If completed, clear the current positioning command and return to step S2.

[0035] For step S1-2-2, the real-time comparison of the size between the actual torque M t of the current servo motor and the torque threshold M0 specifically includes the following steps:

[0036] s1: Determine the size of the real-time torque M t and the torque threshold M0.

[0037] According to the comparison result of s1, the following steps are carried out respectively:

[0038] s2-1: When M t < M0, the servo motor is in the normal operation state, and the servo motor continues to execute the positioning command until the positioning command is completed and cleared, and waits for the next positioning command.

[0039] s2-2: When M t ≥ M0, the control system of the forming machine starts timing and records the actual duration t t when M (act) > M0.

[0040] s3: Determine M t >The actual duration of M0 t (act) With the preset limit time t (set) size;

[0041] According to the comparison result of s3, perform the following steps respectively:

[0042] s4-1: When t (act) < t (set) When the servo motor continues to execute the positioning command, it will reset to zero after completing the positioning command and wait for the next positioning command.

[0043] s4-2: When t (act) >t (set) When the servo motor stops the current positioning instruction, the molding machine stops and an alarm is issued.

[0044] In the process of the servo motor executing the positioning command, the actual torque of the servo motor is judged in real time. t When the torque threshold M0 is less than the molding machine, the molding machine is in normal operation, and the servo motor also executes the received positioning command normally. t When the torque threshold M0 is reached, the actual duration t of the exceeded state is recorded. (act) , forming a torque buffer period, which can provide time for positioning instructions or other parts to continue to execute. (set) The internal servo motor can complete the positioning command and continue to wait for the next positioning command, and the molding machine does not need to alarm; if the torque exceeds the actual duration of the state t (act) Exceeding the preset duration t (set) , the current positioning instruction is cleared and a forced stop instruction is issued to the servo controller, forcing the servo motor to stop and issue an alarm message, instead of directly issuing an interrupt request, triggering an alarm and stopping the operation of the entire molding machine once the torque threshold is exceeded, thereby reducing the frequency of the molding machine's alarm shutdown and maintenance restart, extending the effective operating time of the molding machine, reducing the molding machine's downtime loss, and protecting the molding machine from mechanical damage caused by improper collision due to loose parts falling or other emergencies. At the same time, the molding machine alarms to promptly prompt the operator so that the fault can be judged and repaired as soon as possible.

[0045] In addition, the production parameters are set on the interactive interface of the molding machine as the triggering condition of the positioning instruction. This is based on the ModbusTCP communication protocol integrated by the touch screen and PLC, and data is read and written to each other through the Ethernet physical communication method.

[0046] In addition, it should be noted that the names of the various parts of the specific embodiments described in this specification may be different, and any equivalent or simple changes made based on the structure, features and principles described in the patent concept of the present invention are included in the protection scope of the patent of the present invention. The technicians in the technical field of the present invention can make various modifications or supplements to the specific embodiments described or replace them in a similar manner, as long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A servo positioning control method for a molding machine control system, characterized in that The following steps are involved: (1) Set up a positioning instruction trigger subroutine and a torque protection subroutine in the PLC, where the positioning instruction trigger subroutine includes the following steps: (1-1-1) Set the trigger conditions for sending positioning instructions; (1-1-2) receiving a control signal from a control system of the molding machine; (1-1-3) Determine whether the control signal meets the trigger condition. If the trigger condition is met, the PLC sends a positioning command to the servo controller to control the servo motor to perform the corresponding positioning action, and then execute the torque protection subroutine; The torque protection subroutine includes the following steps: (1-2-1) Set the torque threshold and the time limit for exceeding the torque threshold; (1-2-2) Receive the actual torque of the servo motor fed back by the servo controller, compare the actual torque with the torque threshold, and when the actual torque is greater than and lasts for longer than the limit time, clear the current positioning command and send a forced stop command to the servo controller, forcing the servo motor to stop, and send an alarm message; (2) Execute the positioning instruction to trigger the subroutine; (3) Determine whether the current positioning instruction has been executed. If it has been completed, clear the current positioning instruction and return to step (2); For step (1-2-2), the actual torque M of the current servo motor t When the magnitude of the torque threshold M0 is compared in real time, the following steps are specifically included: s1: Determine the real-time torque M t and the magnitude of the torque threshold M0; According to the comparison result of s1, perform the following steps respectively: s2-1: When M t <When M is less than M0, the servo motor is in a normal operating state. The servo motor continues to execute the positioning command until the positioning command is completed, then clears, and waits for the next positioning command; s2-2: When M t ≥M0, the molding machine control system starts timing and records M t >The actual duration of M0 t (act) ; s3: Determine M t >The actual duration of M0 t (act) With the preset limit time t (set) size; According to the comparison result of s3, perform the following steps respectively: s4-1: When t (act) < t (set) When the servo motor continues to execute the positioning command, it will reset to zero after completing the positioning command and wait for the next positioning command. s4-2: When t (act) >t (set) When the servo motor stops the current positioning instruction, the molding machine stops and an alarm is issued.

2. The servo positioning control method of the molding machine control system according to claim 1, characterized in that: The trigger condition in the step (1-1-1) is a trigger signal, the control signal in the step (1-1-2) is a production parameter preset by the molding machine control system, and the step (1-1-3) determines whether the control signal satisfies the trigger condition by converting the production parameter into a trigger signal, and when the trigger signal is triggered, determining that the trigger condition is satisfied.

3. The servo positioning control method of the molding machine control system according to claim 2, characterized in that: The trigger signal in step (1-1-1) is a time pulse signal, and the step (1-1-3) of judging whether the control signal satisfies the trigger condition is specifically as follows: the production parameter is converted into a time pulse signal, and when the time pulse signal is triggered, it is judged that the trigger condition is met.

4. The servo positioning control method of the molding machine control system according to claim 3, characterized in that: The production parameters are preset on the human-machine interaction interface of the molding machine control system.

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