Blanking speed stable control system and method for hydraulic fine blanking machine

Abstract

The invention discloses a blanking speed stable control system and method for a hydraulic fine blanking machine, and relates to the technical field of hydraulic fine blanking machine control. In order to solve the problems that an existing large-flow pressure compensation valve is high in cost, lagged in response and large in pressure loss, according to the method, blanking parameters are input through a man-machine interaction system, and a blanking load displacement curve is obtained through reasoning by combining a PLC with historical data; in the blanking process, blanking force, energy accumulator pressure and blanking displacement data are recorded in real time, an array relation is formed, and a reasoning instance is updated; drawing a load, energy accumulator pressure and master cylinder displacement curve through a point tracing method, and calculating the pressure difference between an inlet and an outlet of the proportional valve; the valve element displacement of the high-frequency response proportional valve is adjusted based on the corresponding relation between the pressure difference and the displacement of the main cylinder, stable flow compensation is achieved, and then the stable blanking speed is guaranteed. A digital pressure compensation scheme is adopted, the cost is reduced, meanwhile, energy loss is reduced, the section quality and size precision of a fine blanking part are improved, and the service life of the die is prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydraulic fine blanking machine control, in particular to a hydraulic fine blanking machine blanking speed stability control system and method. BACKGROUND

[0002] The blanking speed stability of the hydraulic fine blanking machine directly determines the cross-section quality, dimensional accuracy and service life of the die. In a large-tonnage hydraulic fine blanking machine, the blanking main cylinder is usually matched with a large-flow proportional valve, and the oil source is provided by the accumulator and the oil pump together, and the accumulator pressure fluctuates with the energy release process, resulting in unstable oil source pressure, which further affects the blanking speed of the main cylinder.

[0003] In the prior art, the commonly used speed stability scheme is "servo valve + mechanical pressure compensator", but this scheme has the following defects: first, the cost of the pressure compensator is high, and the adaptability to large flow scenes is poor; second, the mechanical structure response is lagging, and it cannot respond to pressure mutations in time; third, the pressure loss is large, resulting in serious system heating and significant energy loss. If the mechanical pressure compensator is omitted, when the load pressure or oil source pressure changes, the proportional servo valve port opening is fixed, and the valve port pressure difference change will cause flow fluctuation, eventually causing unstable blanking speed, which seriously affects product quality and die life. SUMMARY

[0004] In order to make up for the shortcomings of the prior art, the present application provides a hydraulic fine blanking machine blanking speed stability control method to solve the problems existing in the prior art.

[0005] In order to solve the above technical problems, the present application provides the following technical scheme: A hydraulic fine blanking machine blanking speed stability control system, comprising a man-machine interaction platform, a PLC controller, a main cylinder displacement sensor and a pressure sensor, the man-machine interaction platform and the PLC controller are connected, and the two transmit data through Ethernet, the related data and the reasoning process are realized by the man-machine interaction platform script, and the results are sent to the PLC controller, the main cylinder displacement sensor is used to collect proportional valve spool displacement signal and hydraulic cylinder displacement signal, the pressure sensor is used to collect pressure signal, the PLC controller collects and uploads proportional valve spool displacement, hydraulic cylinder displacement and pressure signal to the man-machine interaction platform, simultaneously processes related signals in real time, and converts output digital quantity into analog quantity instruction signal to send to the proportional valve drive module to realize speed adjustment.

[0006] A hydraulic fine blanking machine blanking speed stability control method based on the above system, comprising the following steps: Step 1, blanking parameter input and curve reasoning: input the material, thickness and circumference parameters of the blanking part through the man-machine interaction system, the PLC controller calculates the blanking force range, and combines with the historical blanking data to reason the blanking load displacement curve; Step 2, punch control preparation: the uplink stage is driven by the main cylinder of the fast cylinder, and the main cylinder absorbs oil through the liquid filling valve; Step 3, data recording and updating: when the main cylinder runs to the punching point, the punching frequency is recorded, and the punching force, punching displacement and accumulator pressure data are collected in real time to form an array relationship, and a new reasoning instance data is generated after comparison with the reasoning curve and stored; Step 4, curve drawing: the load-main cylinder punching displacement curve and the accumulator pressure-main cylinder punching displacement curve are drawn by the dot drawing method; Step 5, differential pressure calculation: according to the pressure value P1 corresponding to the punching force, the accumulator pressure value P2, the ejection cylinder pressure value P3 and the counter-pressure cylinder pressure value P4, the proportional valve inlet and outlet differential pressure is calculated, and the differential pressure-main cylinder displacement relationship curve is obtained; Step 6, digital differential pressure compensation speed control: based on the high frequency response proportional valve, the valve core displacement is quantitatively adjusted according to the corresponding relationship between the flow and the valve core displacement, combined with the differential pressure-main cylinder displacement curve, to realize the stable compensation of the flow and ensure the stable punching speed.

[0007] As a further technical solution of the application: the proportional valve does not participate in the main cylinder motion control in step 1.

[0008] As a further technical solution of the application: the calculation formula of the proportional valve inlet and outlet differential pressure in step 5 is .

[0009] As a further technical solution of the application: the relationship between the flow and the valve core displacement in step (6) satisfies the formula: Wherein K is a constant, related to the valve core area gradient and oil viscosity; is the flow through the proportional valve; is the valve core displacement; and ΔP is the proportional valve inlet and outlet differential pressure.

[0010] As a further technical solution of the application: the four pressure sensors are arranged to collect P1, P2, P3 and P4 pressure data, and the measurement accuracy is not less than 0.1 level.

[0011] As a further technical solution of the application: the main cylinder displacement sensor adopts a magnetostrictive displacement sensor.

[0012] One or more technical solutions provided in the embodiments of the application have at least the following technical effects or advantages: Cost advantage: the digital pressure compensation scheme is used to replace the traditional large flow pressure compensation valve, which significantly reduces the equipment procurement and maintenance cost; Fast response: rely on high frequency response proportional valve and PLC high speed computing ability, real-time response to pressure fluctuations, compensation response speed is superior to mechanical compensation structure; Energy efficient: reduce the pressure loss caused by traditional pressure compensation valve, reduce system energy loss and heat; Strong stability: combined with historical data reasoning and real-time data monitoring, accurate compensation flow fluctuation, ensure the speed of blanking stable, improve the section quality and size accuracy of fine blanking, prolong the service life of the die. BRIEF DESCRIPTION OF DRAWINGS

[0013] Fig. 1 The principle diagram of the hydraulic fine blanking machine blanking speed stable control method; Fig. 2 The block diagram of the hydraulic fine blanking machine blanking speed stable control system; Fig. 3 The structural schematic diagram of the hydraulic fine blanking machine blanking speed stable control system.

[0014] In the figure: 1-fine blanking machine hydraulic system oil tank, 2-oil pump safety pressure valve, 3-oil pump, 4-oil pump pressure relief plug-in valve, 5-main cylinder filling valve control oil port solenoid valve, 6-accumulator, 7-fast cylinder control proportional valve, 8-main cylinder filling valve, 9-main cylinder control proportional valve, 10-fast cylinder one, 11-main cylinder, 12-frequency converter, 13-hydraulic pump drive motor, 14-PLC controller, 15-accumulator pressure sensor, 16-human-computer interaction platform, 17-oil pump outlet check valve, 18-main cylinder pressure relief plug-in valve, 19-main cylinder pressure relief control valve, 20-fast cylinder two, 21-sliding block. DETAILED DESCRIPTION

[0015] The technical solutions in the embodiments of the present application will be described below in a clear and complete manner. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0016] As Figs. 1-3 shown, a hydraulic fine blanking machine blanking speed stable control system, comprising: man-machine interaction platform (reasoning machine data storage record), PLC controller (signal acquisition, data calculation, output control), main cylinder displacement sensor, pressure sensor.

[0017] The man-machine interaction platform is connected with the PLC controller, and both of them transmit data through Ethernet, the relevant data and inference process are realized by the script of the man-machine interaction platform, and the result is sent to the PLC controller, the PLC controller collects and uploads the proportional valve core displacement, hydraulic cylinder displacement and pressure signal to the man-machine interaction platform, simultaneously processes the relevant signals in real time, and converts the output digital quantity into an analog command signal to send to the proportional valve driving module to realize speed regulation.

[0018] Based on the above system, a digital compensation-based master cylinder speed control method is also disclosed, which can realize stable control of the blanking speed of the fine blanking machine under the conditions of blanking different parts and varying inlet pressure of the proportional valve. Unlike traditional valve opening compensation control, the blanking speed is fast, and only the pressure difference calculated by the pressure sensor is used for real-time control. Considering the response time of the proportional valve, it is difficult to realize stable speed control of the fine blanking machine. Since the fine blanking machine is a cycle reciprocating machine, the same part is punched each time, therefore, the present application records the current and historical data for reasoning, analyzes the change relationship between the load and displacement, and compensates the system for the load change effectively, so as to realize stable speed control of the fine blanking machine.

[0019] In order to achieve the above purpose, the present application provides the following technical scheme: The control system of the present application firstly inputs the relevant parameters of the blanking part by the man-machine interaction system, including the blanking material, thickness and circumference, calculates the corresponding blanking force range by the PLC controller, then the PLC control system reasons according to the blanking part parameters and historical data to obtain the closest blanking load displacement curve, and then starts to execute the work of the fine blanking machine, the specific process is as follows: (1) blanking control preparation: in the uplink stage, the main cylinder is driven by the fast cylinder to realize fast uplink, the main cylinder is a plunger cylinder, and oil is sucked through the liquid charging valve, in this process, the proportional valve YB2 does not participate in the main cylinder motion control.

[0020] (2) reasoning and recording: when the main cylinder runs to the blanking point, the control system starts to record the blanking times, and the system records the blanking force and blanking displacement in real time, and the pressure of the accumulator also changes during the process of releasing energy as an auxiliary oil source, therefore, the data of the accumulator pressure and blanking displacement also need to be recorded and compared with the reasoning machine result to form new reasoning instance data for data calling next time.

[0021] (3) curve dotting: the load of the blanked part and the accumulator pressure and main cylinder blanking displacement curve are obtained by dotting method.

[0022] (4) Differential pressure and master cylinder displacement curve acquisition: calculate the differential pressure to obtain the master cylinder displacement relationship curve, wherein the differential pressure calculation involves the blanking force P1 curve, the accumulator pressure P2 curve, the ejection cylinder pressure value P3 and the counter-pressure cylinder pressure value P4, and the inlet and outlet differential pressure of the proportional valve is calculated according to formula 1. (1) (5) Digital differential pressure compensation speed control: based on the fine blanking machine master cylinder speed closed-loop control system, combined with the differential pressure master cylinder displacement curve relationship, the fine blanking machine master cylinder proportional valve adopts a high-frequency response proportional valve, so it is not necessary to consider the dynamic response of the valve, and the flow and the valve core displacement relationship is as follows: wherein K is a constant related to the valve core area gradient and the oil viscosity, and it can be seen from the formula that when the differential pressure increases, in order to ensure the stability of the flow QL, the valve core displacement xv needs to be reduced; when the differential pressure decreases, the valve core displacement xv needs to be increased. The above-mentioned valve core displacement change can be quantitatively given the specific compensation amount according to the differential pressure and the master cylinder displacement.

[0023] The working process of the present application is as follows: The starting PLC controller 14 receives signals sent by the man-machine interaction platform 16 and the hydraulic system accumulator pressure sensor 15, the master cylinder pressure sensor, the valve core displacement sensor, etc. After being ready, the PLC controller 14 sends a command to control the variable frequency motor 13 to operate. The variable frequency motor 13 drives the hydraulic pump 3 to work, and through the oil pump outlet check valve 17, the accumulator 6 is filled with oil. At the same time, the hydraulic pump 3 is connected with the safety cartridge valve 4, and the safety cartridge valve 4 is connected with the safety pressure valve 2. The pressure of the safety pressure valve 2 is adjustable. When the outlet pressure of the oil pump 3 is higher than the overflow pressure of the safety pressure valve 2, the overflow cartridge valve 4 moves right under the action of the oil pressure, and the oil of the oil pump overflows from the overflow cartridge valve 4. During the process of filling the accumulator 6 with oil, the accumulator pressure sensor 15 monitors the accumulator liquid filling pressure. When the pressure of the accumulator 6 reaches the maximum working pressure value, the PLC controller 14 sends a command to reduce the speed of the variable frequency motor 13, thereby reducing the overflow loss of the hydraulic pump 3. During the first blanking, the accumulator 6 acts as an auxiliary oil source. When the PLC controller 14 monitors that the accumulator pressure reaches the maximum working pressure, the valve core of the fast cylinder control valve 7 moves right under the action of the oil pressure, and the fast cylinders 10 and 20 go up. The master cylinder 11 and the fast cylinders 10 and 20 are rigidly connected together through the slide block 21, so the fast cylinders 10 and 20 also push the master cylinder 11 to go up quickly during the upstroke of the fast cylinders 10 and 20. Since the master cylinder 11 is in a passive vacuum state, it starts to suck oil through the filling valve 8. When the master cylinder 11 reaches the displacement set by the PLC controller 14, the fast cylinder control valve 7 is de-energized, and the valve core is in the middle position. At this time, the fast cylinders 10 and 20 are in a floating state. During the blanking process, the master cylinder 11 starts to pressurize and enters the speed control link. The master cylinder pressure relief control valve 19 is energized during the pressurization process of the master cylinder 11. At this time, the control oil port of the pressure relief cartridge valve 18 is connected to the high-pressure oil source, and the master cylinder pressure relief cartridge valve 18 is in a pressure maintaining state. During the blanking stage of the master cylinder 11, the PLC controller 14 starts to adjust the master cylinder control valve 9 according to the master cylinder blanking speed instruction information sent by the man-machine interaction platform 16. At this time, the fast cylinders 10 and 20 are in a floating state, and the master cylinder 11 drives the fast cylinders 10 and 20 to go up through the slide block 21. At this time, based on the circumference, thickness and material information of the blanked part obtained by the man-machine interaction platform 16, the most similar master cylinder pressure and master cylinder displacement relationship and the accumulator pressure and master cylinder displacement relationship historical curve are obtained through the inference machine to realize digital compensation of the valve core displacement. During the blanking process, the PLC controller 14 records and stores the master cylinder pressure and the accumulator pressure and the master cylinder displacement in the form of an array. In the next cycle, comparison and update are performed through the dotting method. After several cycles of dynamic adjustment, the system runs stably and is stored in the inference machine of the man-machine interaction platform 16 as an example, so as to realize expansion of the example library.

[0024] It will be obvious to a person skilled in the art that the application is not limited to the details of the above-described exemplary embodiments, but that the application can be implemented in other embodiments without departing from the scope of the application. The embodiments are therefore to be seen as exemplary and in no way restrictive, the scope of the application being defined by the claims below rather than by the above description, which is intended to encompass all the variations falling within the meaning and the scope of the equivalent elements of the claims.

[0025] Furthermore, it should be understood that although the present specification describes particular embodiments, each of which contains only a single independent technical solution, the specification is written so as to cover all the technical solutions disclosed herein, as a whole, and that the technical solutions in each embodiment have been properly combined, as appropriate, to form other embodiments readily understood by those skilled in the art.

Claims

1. A hydraulic fine blanking machine blanking speed stabilization control system, characterized in that, The system includes a human-machine interface platform, a PLC controller, a main cylinder displacement sensor, and a pressure sensor. The human-machine interface platform is connected to the PLC controller, and the two transmit data via Ethernet. The relevant data and reasoning process are implemented by scripts on the human-machine interface platform, and the results are sent to the PLC controller. The main cylinder displacement sensor is used to collect the proportional valve spool displacement signal and the hydraulic cylinder displacement signal. The pressure sensor is used to collect the pressure signal. The PLC controller collects the proportional valve spool displacement, hydraulic cylinder displacement, and pressure signals and uploads them to the human-machine interface platform. At the same time, it processes the relevant signals in real time and converts the output digital quantity into an analog command signal to send to the proportional valve drive module to realize speed regulation.

2. A method for stabilizing the blanking speed of a hydraulic fine blanking machine, based on the system described in claim 1, characterized in that, Includes the following steps: Step 1, Input of blanking parameters and curve reasoning: Input the material, thickness and perimeter parameters of the blanking part through the human-computer interaction system. The PLC controller calculates the blanking force range and infers the blanking load displacement curve by combining historical blanking data. Step 2, Blanking Control Preparation: During the upward phase, the fast cylinder drives the main cylinder to move upward rapidly, and the main cylinder draws oil through the filling valve; Step 3, Data Recording and Update: When the main cylinder reaches the punching point, record the number of punches, collect punching force, punching displacement and accumulator pressure data in real time to form an array relationship, compare it with the inference curve to generate new inference instance data and store it; Step 4, Curve Plotting: Plot the load-master cylinder punching displacement curve and the accumulator pressure-master cylinder punching displacement curve using the point plotting method; Step 5, Pressure difference calculation: Based on the pressure value P1 corresponding to the punching force, the accumulator pressure value P2, the ejector cylinder pressure value P3, and the counter-pressure cylinder pressure value P4, calculate the pressure difference between the inlet and outlet of the proportional valve to obtain the pressure difference-main cylinder displacement relationship curve. Step 6, Digital Differential Pressure Compensation Speed ​​Control: Based on a high-frequency response proportional valve, the valve core displacement is quantitatively adjusted according to the correspondence between flow rate and valve core displacement, combined with the differential pressure-main cylinder displacement curve, to achieve stable flow rate compensation and ensure stable punching speed.

3. The method for stabilizing the blanking speed of a hydraulic fine blanking machine according to claim 2, characterized in that, The proportional valve does not participate in the master cylinder motion control in step 1.

4. The method for stabilizing the blanking speed of a hydraulic fine blanking machine according to claim 3, characterized in that, The formula for calculating the pressure difference between the inlet and outlet of the proportional valve in step 5 is as follows: .

5. The method for stabilizing the blanking speed of a hydraulic fine blanking machine according to claim 4, characterized in that, The relationship between flow rate and valve core displacement in step (6) satisfies the following formula: Where K is a constant, which is related to the valve core area gradient and the oil viscosity; The flow rate through the proportional valve; ΔP represents the valve core displacement; ΔP represents the pressure difference between the inlet and outlet of the proportional valve.

6. The method for stabilizing the blanking speed of a hydraulic fine blanking machine according to claim 5, characterized in that, A total of four pressure sensors are provided, which are used to collect pressure data of P1, P2, P3 and P4 respectively, with a measurement accuracy of not less than 0.1%.

7. The method for stabilizing the blanking speed of a hydraulic fine blanking machine according to claim 6, characterized in that, The master cylinder displacement sensor is a magnetostrictive displacement sensor.

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