Improved electric screw press, control system and control method

Abstract

The application relates to an improved electric screw press, a control system and a control method, which comprise a motor driver for controlling the motor to provide rotating power for a screw rod; a PLC as a control center, which is in communication connection with the motor driver; a control power module, which inputs a direct-current power to the PLC through wires 281 and 280A; and various motor circuits, in which three-phase power is connected to corresponding motors through series-connected control switches and relay always-open switches. The application has the advantages of reasonable design, compact structure and convenient use.

Description

Technical Field

[0001] The present invention relates to the field of presses, and more particularly to an improved electric screw press, a control system and a control method. Background Art

[0002] The electric screw press realizes the downward strike and upward return of the slider through a motor. When the driving motor works and rotates forward and backward, it has a great impact on the power grid. The electric load often shows sharp peaks, the impact current is large, the power factor is relatively low, and the driving motor has a serious heating phenomenon.

[0003] In view of the previous electric screw presses (such as CN201210588700.8, a control system and control method for an electric screw press), the applicant has improved the control system and provided a set of improved equipment.

[0004] As a continuous improvement, the inventor has improved the circuit and provided a more advanced control method. Summary of the Invention

[0005] In order to improve the control ability of the electric press, simplify the control process, and thus improve the automation of the equipment, the present invention provides an improved electric screw press, a control system and a control method.

[0006] The present invention includes a motor driver for controlling the motor to provide rotational power to the screw; a PLC, serving as a control center, is communicatively connected to the motor driver; a control power supply module inputs DC power to the PLC through wires 281 and 280A; each motor circuit, three-phase power is connected to the corresponding motor through two groups of series-connected relay normally open switches.

[0007] The present invention includes a movable auxiliary robotic arm configured for the press. There is a telescopic rod portion that horizontally extends and retracts on the auxiliary robotic arm, a machine head that swings on the telescopic rod portion, a magnetic base is provided on the machine head, a measuring probe is provided at the end of the magnetic base, an upper top is provided at the tail of the auxiliary robotic arm, and a telescopic support base is installed on one side of the carrier or on the frame; a Doppler measuring instrument is installed on the top of the telescopic support base; the measuring probe is used to measure the height of the workpiece and the position of the probe of the Doppler measuring instrument.

[0008] This method receives the issued strike signal; performs signal filtering and verification, makes a conditional judgment. When the filtered signal meets the set requirements, marks the start of the strike, otherwise does not start; determines the motor drive mode and the strike sequence; inputs the strike speed and start command to the register; starts the strike action; opens the brake valve of the flywheel at the beginning moment; delays and issues a start command to the corresponding motor.

[0009] This method includes signal filtering and verification; among them, in the step of performing signal filtering and verification, a rotational speed measurement filtering algorithm is executed.

[0010] First, make a prediction; X(K+1) = X(K-1) + Q;

[0011] Where X(K+1) is the estimated rotational speed at time K+1; K is time; X(K-1) is the rotational speed at time K-1; and Q is the system process noise figure.

[0012] Secondly, perform the filtering dispute calculation; KF=X(K+1) / (X(k+1)+R);

[0013] Where R is the process noise figure; KF is the filter gain coefficient;

[0014] Next, the rotational speed is estimated and calculated as follows: Y(K) = Y(K-1) + KF*[D(K) - Y(k-1)]; where Y(K) is the current rotational speed after optimization; and D(K) is the actual measured value at time K.

[0015] Next, the estimation error is calculated; X(K) = X(K+1)*(1-KF);

[0016] The prediction filtering algorithm is completed through iterative loops.

[0017] Before the slider descends to strike the workpiece, firstly, the lower surface of the pressure head at the bottom of the slider is monitored using a Doppler measuring instrument. Then, when the Doppler measuring instrument detects that the downward movement of the lower surface of the pressure head reaches the set time and / or the speed changes, it indicates that the pressure head has contacted the workpiece. The slider changes from being pulled down by gravity to the screw descending by the screw for one thread clearance s to press down on the slider. The thread clearance s = (V1-V2) ×T-(H1-H2) or s = V3×T; V1 is the downward speed of the pressure head when it contacts the workpiece, V2 is the initial pressure speed after the pressure head contacts the workpiece, T is the time interval between V1 and V2, H1 is the height of the pressure head when it contacts the workpiece, H2 is the initial pressure height after the pressure head contacts the workpiece, and V3 is the screw rotation speed.

[0018] The present invention includes a frame, a platform and a slider that is raised and lowered on the platform; a control system and / or a control method are provided on the frame.

[0019] In summary, the present invention has at least one of the following beneficial technical effects:

[0020] This invention improves existing circuit design by using PLC and relays to achieve interlocking and linkage control, thereby ensuring the safety of the control system. It also improves the control method by designing mid-position control and filtering functions, achieving precise control, noise reduction, and high reliability. The invention employs an improved filtering and noise reduction scheme. Furthermore, it uses Doppler for distance and speed testing, allowing for screw rotation speed determination. A probe is used to measure the workpiece's high point and record the Doppler radar coordinates. Doppler ranging and upward / downward position control are achieved through gap measurement and upward / downward positioning. This invention achieves precise control through filtering, noise reduction, and gap compensation. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the preferred structure of the press.

[0022] Figure 2 This is the main circuit main motor control diagram.

[0023] Figure 3 This is the main circuit control diagram for the slave motor.

[0024] Figure 4 It is a control diagram for controlling the power supply.

[0025] Figure 5 This is part of the control diagram I for the main circuit motor.

[0026] Figure 6 This is Part II of the control diagram for the main circuit motor.

[0027] Figure 7 This is a fan lubrication control diagram.

[0028] Figure 8 It is a PLC control diagram.

[0029] Figure 9 This is PLC input control diagram I.

[0030] Figure 10 This is PLC input control diagram II.

[0031] Figure 11 This is PLC input section control diagram III.

[0032] Figure 12 This is control diagram I for the PLC output section.

[0033] Figure 13 This is the PLC I / O input control diagram for the robotic arm (Figure I).

[0034] Figure 14 This is the PLC I / O input control diagram for the robotic arm, Part II.

[0035] Figures 15-24 It is a workflow diagram.

[0036] Figure 25 This is a finite structure diagram of a press.

[0037] Explanation of reference numerals in the attached drawings: 1. Platform; 2. Slider section; 3. Auxiliary robotic arm; 4. Top; 5. Measuring probe; 6. Magnetic base; 7. Telescopic rod section; 8. Telescopic support base; 9. Doppler measuring instrument. Detailed Implementation

[0038] The following is in conjunction with the appendix Figure 1-25 The present invention will be further described in detail below. The technical solutions and features of the various embodiments can be used individually or in combination.

[0039] like Figure 1 The press performs the following steps: receiving the incoming strike signal; filtering and verifying the signal, and making condition judgments. If the filtered signal meets the set requirements, the strike is marked as started; otherwise, it does not start; determining the motor drive mode and strike sequence; inputting the strike speed and start command into the register; the strike action begins; opening the flywheel brake valve at the moment of start; and issuing a start command to the corresponding motor after a delay.

[0040] After inputting the strike speed and start command into the register, the motor speed is written.

[0041] After a delay, a start command is issued to the corresponding motor, and then the motor control write operation is performed.

[0042] The encoder performs signal-to-data conversion, speed detection, and determines the upper position signal, middle position signal, and lower position signal status of the slider.

[0043] After the delay, the start command is sent to the corresponding motor. It is determined that the slider is in the lower signal state, and the lower signal command to be detected is executed.

[0044] When a motor reverse command is given, the slider moves to the upper position and the upper position signal status is determined, then motor braking and mechanical braking are performed.

[0045] When a motor reverse command is given, the motor control write operation is performed.

[0046] Through the above process, the press is controlled, and the entire process is automated through the switch. The addition of mid-position control enables position verification, avoids identification errors, and thus improves the accuracy of control.

[0047] like Figure 2-15The power control section includes a motor driver, which controls the motor to provide rotational power to the screw; a PLC, which acts as the control center and communicates with the motor driver; a control power module, which supplies DC power to the PLC through wires 281 and 280A to ensure the voltage stability of the PLC; and three-phase power to each motor circuit, which is connected to the corresponding motor through two sets of series-connected normally open relay switches, thereby achieving double protection and remote low-voltage control.

[0048] The motor control module includes a master motor control module and a slave motor control module connected in parallel with identical circuit structures; such as Figure 1 The main motor control module includes the main switch KM11, which is controlled by the relay switch of line 233 and line 281 to achieve low voltage control of high voltage, which is safe and reliable. The input terminal of the main switch KM11 is connected to the mains power through the main relay QF11 and the output terminal supplies power to the main controller. The main controller is electrically connected to the PLC to control the rotation of the main motor SRM, thereby realizing intelligent control.

[0049] like Figure 8 The PLC is electrically connected to a touchscreen via a switch and debugging module; for example... Figure 3 Control power module, AC power is supplied through power transformer TC1, with a voltmeter connected in parallel to the primary coil. A constantly lit power indicator light HL1 is connected to the secondary coil to indicate the circuit status and ensure power supply safety. After passing through the normally open power switch SA1, one path of the secondary coil is connected to an AC-to-DC module, outputting DC power through lines 280 and 281; another path outputs AC power through line 237; and a third path is connected to a relay control circuit. This circuit includes a normally closed relay switch SB2 connected to the normally open power switch SA1. The output of normally closed relay switch SB2 is connected in parallel to a branch of normally open relay switch SB1 and a series branch of normally open switches KM1 and KM2. Then, the control coils of relays KM1 and KM2 are connected in parallel. This achieves interlocking control. If one of the control coils of relays KM1 or KM2 malfunctions, both normally open switches of relays KM1 and KM2 will open, providing protection. SB2 is an emergency switch, and SB1 is used for pilot control.

[0050] like Figure 5 The motor circuit includes a top material pump for driving the platform 1 to rise and fall, a lubrication pump for lubrication, and a cooling fan.

[0051] like Figure 15Procedure 1: When an external strike signal M0.6 is received, it is filtered for 200ms. When the filtered signal is confirmed to meet the preset conditions, the strike is initiated, the photoelectric protection signal M4.7 is activated, and the photoelectric protection signal M4.7 is verified to see if an object has entered the working area. The program strike start command M13.0 is then executed.

[0052] Among them, the external strike signal filtering timer T130 is used to filter abnormal interference; strike signal M13.4 is allowed; and single-control equipment or online control equipment judges V1700.0.

[0053] like Figure 16 Process 2: When the program starts executing the start command M13.0, the transmission mode of the current device is determined, and the forward and reverse rotation speed of the motor is assigned to the relevant registers of the communication protocol. Then, the data writing process begins, and the automatic working program is entered.

[0054] Among them, the strike signal is allowed (M13.4); the program strike instruction is (M13.0); the strike sequence data is (VW918); the motor drive form data is (VW226); the motor forward rotation speed is (VW208); the motor reverse rotation speed is (VW210); the register strike speed is (VW974); the register return speed is (VW972); the motor speed write instruction is (M17.1); and the strike action start instruction is (M20.0).

[0055] like Figure 17 In process 3, when the automatic working program of process 2 is entered, the motor rotates forward and the slider begins to descend. When the slider position is detected to have reached the specified point, a reverse allow control command is sent to the motor and the slider descent is marked as complete in the program.

[0056] VW226 Motor control instructions; VW904 Register control instructions; M8.0 External brake valve; M8.1 Motor drive enable signal; M13.6 Slider lower position signal; T116 Delayed transmission timer for motor control signals; M17.0 Motor control signal; M20.1 Slider descent completion signal.

[0057] like Figure 18 In process 4, after the slider has finished descending, the motor starts to rotate in the opposite direction. When the slider position is detected to have reached the designated point, a motor braking command is sent to the motor, and the slider is marked as having completed its work in the program.

[0058] VW228 Motor reverse start data; VW230 Motor braking stop data; VW904 Register control instructions; M13.5 Slider upper signal bit; M20.2 Slider upper movement completion signal bit; M20.3 Hydraulic ejection start signal bit; M14.4 Hydraulic ejection start output.

[0059] like Figures 19-20Furthermore, a position detection process 5 is executed. The PLC receives pulse signals generated by limit switches, sensors, current changes, or level changes, and converts them into position data; based on the position data, it determines the position of the slider and feeds it back to the PLC control system.

[0060] Among them, SM0.0 is always on; VD500 pulse data; VD536 pulse conversion position coefficient; VD512 position data; MUL_R multiplication operation;

[0061] like Figure 21 It also executes process 6, which writes motor control and speed;

[0062] M17.1 Motor speed write command; M17.0 Motor control write command;

[0063] VB237 motor slave address; &VB972 register address start symbol; M26.0 and M26.1 communication completion pulses; VB909 and VB911 communication failure codes;

[0064] like Figure 22-23 Step 7: Based on the position information, determine the position of the slider and feed back the slider's lower and middle position signals to the control system;

[0065] like Figure 24 Mark the process of sliding the slider down.

[0066] VD512 Position data; VD580 Slider stop data; Perform floating-point data comparison; M13.5 Slider upper signal bit; VD1100 Enable upper data for triggering; M15.3 Slider enable automatic triggering signal bit; VD20 Slider lower data; M13.6 Slider lower signal bit;

[0067] In process 1, when the slider rotation speed is measured using a pulse incremental encoder, noise data may be generated in the speed detection waveform due to PLC interruption time offset or external mechanical vibration. Therefore, a predictive filtering algorithm is used to filter the detection results to make the data closer to the true data.

[0068] In the signal filtering and verification step, the speed measurement filtering algorithm is executed.

[0069] First, make a prediction; X(K+1) = X(K-1) + Q;

[0070] Where X(K+1) is the estimated rotational speed at time K+1; K is time; X(K-1) is the rotational speed at time K-1; and Q is the system process noise figure.

[0071] Secondly, perform the filtering dispute calculation; KF=X(K+1) / (X(k+1)+R);

[0072] Where R is the process noise figure; KF is the filter gain coefficient;

[0073] Next, the rotational speed is estimated and calculated as follows: Y(K) = Y(K-1) + KF*[D(K) - Y(k-1)]; where Y(K) is the current rotational speed after optimization; and D(K) is the actual measured value at time K.

[0074] Next, the estimation error is calculated; X(K) = X(K+1)*(1-KF);

[0075] The prediction filtering algorithm is completed by iterating through the above four steps.

[0076] like Figure 25 The press includes a platform 1 and a slider 2. During operation, the screw press rotates in both directions to achieve lifting and lowering. As the lifting part, there is a clearance between the bolt and nut, and a gap may also exist between the lifting part and the slider 2 connected to its lower end. For example, when the bolt is connected to the slider 2, as the slider 2 descends, under the influence of gravity, the lower surface of the bolt's thread contacts the upper surface of the thread below the nut, creating a thread gap with the lower surface above the nut. When the slider 2 contacts the workpiece on the platform 1, the lower surface of the bolt's thread separates from the upper surface of the thread below the nut. At this time, the nut continues to rotate, making pressure contact with the lower surface above the nut and performing a downward pressing action. This gap causes a stroke matching error, affecting the downward pressure. Using a pressure sensor for control requires program adjustment each time, and under high speed and high pressure, the closed-loop feedback sensor is easily damaged.

[0077] To monitor the clearance and improve control accuracy, a movable auxiliary robotic arm 3 is provided. A telescopic rod 7 extends horizontally on the auxiliary robotic arm 3. A machine head swings on the telescopic rod 7, and a magnetic seat 6 is installed on the machine head. A measuring probe 5 is installed at the end of the magnetic seat 6. An upper top 4 is installed at the tail of the auxiliary robotic arm 3. A telescopic support 8 is installed on one side of the platform 1 or on the frame. It can be magnetically or bolted. Its installation position can be adjusted according to different workpieces, and its height can be adjusted by the telescopic part. A Doppler measuring instrument 9 is installed on the top of the telescopic support 8. It is used to measure the real-time downward height of the pressure head installed under the slider 2. When the height reaches the set point and / or the speed changes, it indicates that the pressure head has contacted the workpiece. The slider changes from being pulled down by gravity to the screw moving down by the screw for one thread clearance s and pressing down on the slider. After the pressure head reaches the set height, the upper top 4 pushes the pressure head up, so that the pressure head moves upward. This upward distance is mainly the thread clearance S, which may include related fit clearances or assembly errors. Doppler measurement of the upward distance compensates for motor rotation, achieving open-loop control and enabling precise parameter compensation for the downward distance of the slider. This invention achieves precise control through filtering and noise reduction, as well as gap compensation. Figure 25 The diagram shown in the middle is a simplified illustration, and its structure does not limit the scope of protection.

[0078] The implementation principle of an improved electric screw press, control system, and control method according to an embodiment of the present invention is as follows: During operation, the user installs a movable auxiliary robotic arm 3 at the bottom of the press frame. Depending on the specifications of different presses and workpieces, different magnetic bases 6 are used, and the extension is adjusted via the telescopic rod 7. The high point position of the workpiece fixed on the platform 1 is measured using a measuring probe 5 to determine parameters such as the position height of the Doppler measuring instrument 9 and the initial position of the lower surface of the press head. Then, pressure measurement is performed. Preferably, the press head can be run at low speed during initial measurement to ensure that V2 is zero.

[0079] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. An improved control system for an electric screw press, characterized in that: It includes a motor driver, which controls the motor to provide rotational power to the screw; a PLC, which acts as the control center and communicates with the motor driver; a control power module, which inputs DC power to the PLC through lines 281 and 280A; and each motor circuit, with three-phase power connected to the corresponding motor through a series control switch and a normally open relay switch. Includes a movable auxiliary robotic arm (3) for use with a press, a telescopic rod (7) that extends horizontally on the auxiliary robotic arm (3), a machine head that swings on the telescopic rod (7), a magnetic seat (6) on the machine head, a measuring probe (5) at the end of the magnetic seat (6), an upper top (4) at the tail of the rotating auxiliary robotic arm (3), a telescopic support seat (8) on one side of the platform (1) or on the frame; a Doppler measuring instrument (9) on the top of the telescopic support seat (8); the measuring probe (5) is used to measure the height of the workpiece and the position of the Doppler measuring instrument (9); the upper top (4) is used to press the upper pressure head; The following control methods are also included: Before the slider moves downward to strike, firstly, the lower surface of the pressure head at the bottom of the slider part (2) is monitored by a Doppler measuring instrument (9); then, when the Doppler measuring instrument (9) monitors the lower surface of the pressure head to reach the set time and / or the speed changes, it indicates that the pressure head has contacted the workpiece, and the slider changes from gravity pulling down the screw to the screw moving down one thread gap s to press down on the slider, the thread gap s=(V1-V2) ×T-(H1-H2) or s=V3×T; V1 is the downward speed when the pressure head contacts the workpiece, V2 is the initial pressure speed after the pressure head contacts the workpiece, T is the time interval between V1 and V2, H1 is the height when the pressure head contacts the workpiece, H2 is the initial pressure height after the pressure head contacts the workpiece; V3 is the screw speed; Receive the transmitted strike signal; filter and verify the signal, perform condition judgment, and mark the start of strike if the filtered signal meets the set requirements, otherwise do not start; determine the motor drive mode and strike sequence; input the strike speed and start command into the register; the strike action begins; open the flywheel brake valve at the moment of start; and issue a start command to the corresponding motor after a delay. The method includes speed measurement signal filtering and estimation; wherein, in the signal filtering step, a speed measurement filtering algorithm is executed; First, make a prediction; X(K+1) = X(K-1) + Q; Where X(K+1) is the estimated rotational speed at time K+1; K is time; X(K-1) is the rotational speed at time K-1; and Q is the system process noise figure. Secondly, perform the filtering dispute calculation; KF=X(K+1) / (X(k+1)+R); Where R is the process noise figure; KF is the filter gain coefficient; Next, the rotational speed is estimated and calculated as follows: Y(K) = Y(K-1) + KF*[D(K) - Y(k-1)]; where Y(K) is the current rotational speed after optimization; and D(K) is the actual measured value at time K. Next, the estimation error is calculated; X(K) = X(K+1)*(1-KF); The prediction filtering algorithm is completed through iterative loops.

2. The improved electric screw press control system according to claim 1, characterized in that: The motor control module includes a main motor control module and a slave motor control module connected in parallel with identical circuit structures. The main motor control module includes a master switch KM11, controlled by relay switches via lines 233 and 281. The input terminal of the master switch KM11 is connected to AC power via the main control switch QF11, and its output terminal supplies power to the master controller. The master controller is electrically connected to a PLC to control the rotation of the main motor. The PLC is electrically connected to a touchscreen via a switch and debugging module. The control power module is connected to AC power via a power transformer TC1, with a voltmeter connected in parallel to the primary coil. A normally lit power indicator HL1 is electrically connected to the secondary coil. The secondary coil is connected to a normally open power supply. After switch SA1, one line is connected to an AC to DC module and outputs through lines 280 and 281; another line outputs AC power through line 237; and another line is connected to a relay control circuit. The relay control circuit includes a normally closed relay switch SB2 that is electrically connected to the normally open power switch SA1. The output of the normally closed relay switch SB2 is connected in parallel to the normally open relay switch SB1 branch and the series branch of the normally open switches of relays KM1 and KM2. After that, the control coils of relays KM1 and KM2 are electrically connected in parallel. The motor circuit includes a top material pump for driving the lifting of the platform (1), a lubrication pump for lubrication, and a cooling fan.

3. The improved electric screw press control system according to claim 1, characterized in that: The Doppler measuring instrument (9) is used to measure the real-time height of the downward movement of the pressure head installed on the lower surface of the slider part (2) when it reaches the set point and / or the speed changes; the Doppler measuring instrument (9) is used to measure the height between the front and rear of the upper pressure head of the upper top (4) and to obtain the distance difference.

4. The improved electric screw press control system according to claim 1, characterized in that: in, After inputting the strike speed and start command into the register, the motor speed is written; after a delay, the motor control is written after issuing the start command to the corresponding motor. The encoder performs signal-to-data conversion, speed detection, and determines the upper position signal, middle position signal, and lower position signal status of the slider. After the delay, the start command is sent to the corresponding motor. It is determined that the slider is in the lower signal state, and the lower signal command to be detected is executed. When a motor reverse command is given, the slider moves to the upper position and the upper position signal state is determined, then motor braking and mechanical braking are performed. When a motor reverse command is given, the motor control write operation is performed.

5. The improved electric screw press control system according to claim 4, characterized in that: Procedure 1: When the signal meets the preset conditions, verify whether the photoelectric protection signal M4.7 has entered the working area, strike it, and start executing the program strike start command M13.0; Process 2; When the program starts executing the start command M13.0, the transmission mode of the current device is determined, the forward and reverse rotation speed of the motor is assigned to the relevant registers of the communication protocol, and the data writing process begins. After that, the automatic working program is entered. In process 3, when the automatic working program of process 2 is entered, the motor rotates forward and the slider begins to descend. When the slider position is detected to have reached the designated point, a reverse allow control command is sent to the motor and the slider descent is marked as complete in the program. Step 4: After the slider has finished descending, the motor starts to rotate in the opposite direction. When the slider position is detected to have reached the designated point, a motor braking command is sent to the motor, and the slider is marked as having completed its work in the program. The method also includes a position detection process 5; the PLC receives pulse signals generated by limit switches, sensors, current changes, or level changes, and converts them into position data; based on the position data, the position of the slider is determined and fed back to the PLC control system; The method also includes process 6, which writes the motor control and speed settings; When an external attack signal M0.6 is received, it is filtered over a period of 200ms.

6. An improved electric screw press, characterized in that: The device includes a frame, on which a platform (1) is provided and a slider (2) is provided for lifting and lowering on the platform (1); and on which the control system according to any one of claims 1-5 is provided.

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