Servo forging press transmission system and control method

Abstract

The invention discloses a servo forging press transmission system and a control method, and mainly relates to the technical field of servo press transmission control. Comprising an energy storage mechanism, a control mechanism, a transmission mechanism, a flywheel and a working mechanism, the energy storage mechanism is electrically connected with the control mechanism, the control mechanism is in electrical connection and data connection with the transmission mechanism, and the transmission mechanism is in mechanical connection with the flywheel and the working mechanism. The servo motor has the beneficial effects that the power requirement of the servo motor can be greatly reduced, and meanwhile, the equipment cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of servo press transmission control, in particular to a servo forging press transmission system and a control method. Background Art

[0002] The servo press is a mechanical press commonly used for forging materials such as steel, with a crank-connecting rod structure (see patent document, ZL200720029322.4: Integral body hot die forging press). The main features of this press are that the motor drives the flywheel to rotate through a reduction mechanism, the flywheel is connected to the crankshaft through a clutch, the crankshaft rotates to drive the crank and connecting rod mechanism, the connecting rod drives the slider to slide up and down, completing the extrusion process of the workpiece under the slider, and after the process is completed, the crank continues to rotate, driving the slider to return to the top dead center. Finally, the flywheel is separated from the crankshaft and the slider stops. The main disadvantages of this press are:

[0003] 1. The speed is fixed and uncontrollable, resulting in low utilization of flywheel kinetic energy, poor equipment process adaptability, low part yield, and fast mold loss;

[0004] 2. The friction clutch has large power loss and high energy consumption of the equipment;

[0005] 3. The transmission mechanism has great impact and its parts wear out quickly.

[0006] In view of the shortcomings of traditional mechanical presses, the industry has proposed the concept of servo presses, patents: 201120293348.6 Servo press transmission system, 201110231330.8 A servo press control method, its main features are:

[0007] 1. The clutch is cancelled, and the servo motor directly drives the slider through the transmission system;

[0008] 2. Eliminate the flywheel, and all the energy required for the slider to process the workpiece comes directly from the electromagnetic torque of the servo motor;

[0009] Through the above measures, the existing patented technology solves some of the problems of traditional mechanical presses, and can be well applied to stamping processes such as stretching and blanking, but it is difficult to use in forging processes. The main reason is that there are important differences between forging and stamping processes. The stamping process requires that the slider has a slower speed within the working stroke close to the bottom dead center, and the servo motor only needs to output a larger torque, so that the motor power is within an acceptable range (power = speed x torque). The forging process requires the motor to output both the maximum torque and the highest speed within the working stroke, which makes the servo motor very powerful, often reaching several times or even dozens of times that of the stamping process. This makes the servo motor not only costly, but also large in size and heavy in weight, which is technically difficult to achieve.

[0010] Therefore, there is an urgent need for a crank-connecting rod structure servo press for forging and a control method thereof to solve the above problems. Summary of the invention

[0011] The object of the present invention is to provide a servo forging press transmission system and control method, which can significantly reduce the power demand of the servo motor and reduce the equipment cost.

[0012] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0013] On the one hand, a servo forging press transmission system is provided, including an energy storage mechanism, a control mechanism, a transmission mechanism, a flywheel and a working mechanism, wherein the energy storage mechanism is electrically connected to the control mechanism, the control mechanism is electrically and data-connected to the transmission mechanism respectively, and the transmission mechanism is mechanically connected to the flywheel and the working mechanism.

[0014] Preferably, the energy storage mechanism is specifically an energy storage capacitor, and the control mechanism includes a servo controller, a press controller and a crankshaft encoder, the servo controller is bidirectionally electrically connected to the energy storage capacitor, the servo controller is bidirectionally data connected to the press controller, the crankshaft encoder is unidirectionally data connected to the press controller, and the crankshaft encoder is used to measure the crankshaft angle.

[0015] Preferably, the transmission mechanism includes a servo motor, which is electrically connected to a servo controller and is provided with a motor encoder for measuring the position and speed of a servo motor rotor, and the motor encoder is unidirectionally data-connected to the servo controller.

[0016] Preferably, the servo motor is provided with an output end, the output end is connected to a reduction mechanism, the reduction mechanism includes a pinion and a gear, the pinion is meshed with the gear, the pinion is connected to the output end of the servo motor, and the gear is coaxially connected to the flywheel.

[0017] Preferably, a crank is provided on the large gear, the crank is coaxially arranged with the large gear, and the end of the crank is connected to the working mechanism.

[0018] Preferably, the working mechanism includes a connecting rod, the top end of the connecting rod is connected to the crank, the bottom end of the connecting rod is connected to a slider, guide rails are arranged on both sides of the slider, the guide rails are arranged vertically, and the slider slides up and down along the extension direction of the guide rails, and a workbench is arranged at the bottom end of the guide rail without contact.

[0019] On the other hand, a control method for the servo forging press transmission system is provided, comprising the following steps:

[0020] S1: The press enters the process from the standby state. At this time, the controller sends a standby command, making the crank angle equal to 0, the slider at the top dead center, and the motor speed equal to 0;

[0021] S2: The controller checks the user interface to see if there is a start command. If no command is sent, it returns to step S1 and remains in standby mode. If a command is sent, it executes the next step.

[0022] S3: Speed ​​control is performed, the crank rotates clockwise and accelerates rapidly, and the target speed is equal to the preset speed n;

[0023] S4: During the operation, the crank angle is continuously collected. If the angle does not exceed 180 degrees, step S3 is repeated, otherwise the next step is executed;

[0024] S5: Check whether the operation mode of this cycle is continuous operation or single stroke mode: if it is continuous operation mode, return to step S3, continue the speed control with the target speed equal to n, and continue the next cycle after the crank returns to 360 degrees; if it is single stroke mode, proceed to the next step;

[0025] S6: Speed ​​control is performed, the crank rotates clockwise to make the slider return, and the target speed is equal to n;

[0026] S7: Calculate in real time whether the angle difference between the current crank position and the top dead center position is less than or equal to the crank angle required for servo motor braking: If not, return to step S6 and continue speed control; otherwise return to step S1, the controller sends a standby command to make the motor stop at the crank position of 0 degrees according to the preset deceleration. During the stopping process, the servo controller commands the servo motor to operate in the power generation mode, and the generated electrical energy is temporarily stored in the energy storage mechanism.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] 1. Compared with the existing servo press technology, this patented technology can significantly reduce the power demand of the servo motor, which not only makes the cost of the servo forging press within an acceptable range, but also makes the overall structure of the press reasonable, the center of gravity lowered, and the overall stability due to the significant reduction in the size and weight of the motor, and also makes the servo forging press technically feasible;

[0029] 2. Compared with traditional non-servo forging presses, firstly, the striking speed of each forging strike in the patented method can be flexibly adjusted according to the process requirements, which helps to improve the yield rate and reduce mold loss; secondly, the patented method abandons the clutch and eliminates the energy consumption in the clutch process, which helps to save energy and reduce consumption and reduce costs; in addition, the patented method can utilize most of the flywheel kinetic energy for production work, thereby significantly reducing the weight of the flywheel, helping to reduce the center of gravity of the entire equipment, improve stability, and further reduce equipment costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a structural diagram of the crank connecting rod press drive and transmission system of the present invention;

[0031] Figure 2 It is a schematic diagram of the crank movement of the crank-connecting rod servo press forging process of the present invention;

[0032] Figure 3 It is a schematic diagram of the crank connecting rod structure of the present invention;

[0033] Figure 4 It is a control flow chart of the servo forging press of the present invention. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the application equally.

[0035] In the present invention, terms such as "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "side", "bottom", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are relational words determined only for the convenience of describing the structural relationships of the various parts or elements of the present invention, and do not specifically refer to any part or element in the present invention and should not be understood as limitations on the present invention.

[0036] In the present invention, terms such as "fixed connection", "connected", "connection", etc. should be understood in a broad sense, indicating that it can be fixedly connected, integrally connected or detachably connected; it can be directly connected or indirectly connected through an intermediate medium. Relevant scientific research or technical personnel in this field can determine the specific meanings of the above terms in the present invention according to specific circumstances, and they should not be understood as limiting the present invention.

[0037] Example:

[0038] like Figure 1As shown, this embodiment provides a servo forging press transmission system, including an energy storage mechanism, a control mechanism, a transmission mechanism and a working mechanism, wherein the energy storage mechanism is electrically connected to the control mechanism, the control mechanism is electrically and data-connected to the transmission mechanism respectively, and the transmission mechanism is mechanically connected to the working mechanism.

[0039] The energy storage mechanism is specifically an energy storage capacitor, the control mechanism includes a servo controller, a press controller and a crankshaft encoder, the servo controller is bidirectionally electrically connected to the energy storage capacitor, the servo controller is bidirectionally data connected to the press controller, the crankshaft encoder is unidirectionally data connected to the press controller, the crankshaft encoder is used to measure the crankshaft angle, the transmission mechanism includes a servo motor, the servo motor is unidirectionally data connected to the servo controller, and the servo motor is provided with a motor encoder, the motor encoder is used to measure the position and speed of the servo motor rotor, the motor encoder is unidirectionally digitally connected to the servo controller, and the crankshaft encoder is used to measure the crankshaft angle. According to the connection, the servo motor is provided with an output end, and the output end is connected with a reduction mechanism, the reduction mechanism includes a pinion and a large gear, the pinion is meshed with the large gear, the pinion is connected to the output end of the servo motor, a crank is provided on the large gear, the crank is coaxially arranged with the large gear, the end of the crank is connected to the working mechanism, the working mechanism includes a connecting rod, the top end of the connecting rod is connected to the crank, the bottom end of the connecting rod is connected to a slider, guide rails are provided at both ends of the slider, the guide rails are vertically arranged, and the slider slides up and down along the extension direction of the guide rails, and a workbench is provided at the bottom end of the guide rails without contact.

[0040] The large gear increases thickness as needed and also serves as a flywheel. The crank is connected to the slider through a connecting rod mechanism, driving the slider to move up and down along the guide rail. The workpiece to be processed is located between the slider and the workbench, and extrusion molding is completed through a mold.

[0041] The encoder signal is input into the press controller, which sends commands to the servo controller according to the crank angle and process requirements to control the servo motor to generate the required torque and speed; the motor encoder is fixed on the servo motor shaft to measure the position and speed of the motor rotor; the motor encoder signal is sent to the servo controller to achieve precise motor control; the servo motor is coaxially connected to the pinion gear to drive the pinion gear to rotate, and then drive the slider to run through the transmission system; the press controller can also have a user interface and other interfaces to receive user commands and complete other necessary functions. The control process of the press for forging process is as follows: Figure 2 shown.

[0042] The forging process can be divided into three stages according to the process of one crank rotation:

[0043] Stage 1: Acceleration stage, when the crank angle θ is equal to 0, the slider is at the top dead center, and the crank rotates clockwise from 0 degrees to make the slider reach the angle range when it just touches the workpiece position (nominal force stroke position). This is the acceleration stage of the crank. At this time, the flywheel speed reaches the required speed and stores enough kinetic energy.

[0044] Stage 2: Working stage. The range from the crank angle when the slider contacts the workpiece to 180 degrees is the working stage. In this stage, the flywheel is forced to slow down due to the resistance of the workpiece, and the slider continues to work on the workpiece. The mechanical energy originally stored in the flywheel is converted into energy for squeezing the workpiece. When it reaches 180 degrees, the flywheel speed drops to the lowest point, and the load torque is equal to zero. In this stage, the motor continues to output electromagnetic torque to assist in work.

[0045] Stage 3: In the return stage, the crank continues to rotate clockwise from 180 degrees to 360 degrees and returns to the 0-degree position. If you need to continue to perform the next blow without interruption, you can accelerate in the return stage and enter the next cycle after passing 0 degrees. If you need to enter the standby state after completing this blow, you should decelerate and stop in the return stage. In order to return as quickly as possible, you can accelerate first, approach the top dead center at the fastest speed, and then brake to stop.

[0046] The above process includes two different working methods:

[0047] Mode 1, continuous operation mode: the crank rotates continuously without stopping at the top dead center, and the flywheel can accelerate during the return stroke and acceleration phases and enter the working phase;

[0048] Mode 2, single stroke mode: The crank starts to accelerate from a stationary state at the 0-degree position, is forced to decelerate and do work during the working phase, lifts the slider during the return phase, and stops when it reaches the top dead center.

[0049] In order to meet the above process requirements, the system should meet:

[0050] Condition 1: Regardless of the operating mode, the flywheel needs to have sufficient inertia and speed to store enough energy to complete the processing of the workpiece. For this purpose, the flywheel inertia and speed need to be designed and calculated.

[0051] Condition 2: In the single-stroke mode, the servo motor needs to use the acceleration phase to accelerate the flywheel so that it can obtain sufficient kinetic energy. To this end, the motor needs to have sufficient driving torque and power;

[0052] In the return phase under the single-stroke mode, the motor should generate enough torque to stop the flywheel when it reaches the top dead center. Since the motor speed at the starting point of the return (bottom dead center) is lower than the maximum speed and the angle covered by the crank in the return phase is larger than that in the acceleration phase, the motor torque requirement in the return phase is smaller than that in the acceleration phase. Therefore, as long as condition 2 is met, the deceleration and stop requirements in the return phase can be automatically met.

[0053] In this embodiment, a crank connecting rod forging press with a nominal force of 10000 kN is taken as an example. Figure 3 As shown, nominal force Fn = 10000 kN; nominal force stroke hn = 2.5 mm; continuous operation production frequency S = 90 times / minute; crank length Rc = 150 mm; connecting rod length L = 1000 mm; motor to crankshaft reduction ratio Rmc = 10; total transmission system efficiency η = 90%; ratio of the end speed to the start speed of the working stage Rv = 0.7 (about 50% of the kinetic energy is used to do work); the proportion of inertia work in the working stage to the total work energy γ = 0.9;

[0054] Let the press run in single stroke mode, and design and calculate the main parameters of the press:

[0055] Crank angle corresponding to nominal force stroke:

[0056]

[0057] Maximum motor speed:

[0058] n m =R mc S=900(min -1 )=94.25(rad / s)

[0059] Maximum crankshaft and flywheel speed:

[0060] n c =S = 90 (min -1 )=9.42(rad / s)

[0061] Energy required during the working phase:

[0062]

[0063] Motor output energy during working phase:

[0064] W m =(1-γ)W in =2.78(kJ)

[0065] Motor output torque during working phase:

[0066]

[0067] Motor output power during working phase:

[0068] P wm =T wm n m =154(kW)

[0069] Inertia releases energy during the working phase:

[0070] W c =γW in =25(kJ)

[0071] Required flywheel moment of inertia:

[0072]

[0073] Torque required to accelerate the flywheel:

[0074]

[0075] Motor power required for flywheel acceleration:

[0076] P am =T ac n c =173(kW)

[0077] Because the power Pam required for motor acceleration is greater than the motor output power Pwm during the working phase, the motor power should be selected to be no less than Pam = 173kW.

[0078] After completing the above flywheel and motor parameter design, the single stroke time can be tested:

[0079] Time required for the acceleration phase:

[0080]

[0081] Time required for the working phase:

[0082]

[0083] In order to return as quickly as possible, the return phase should be run at the highest possible speed, that is, first accelerate, then decelerate and stop. To this end, first calculate the return peak speed:

[0084]

[0085] Then, calculate the return acceleration time:

[0086]

[0087] Return braking time:

[0088]

[0089] The total time for a single trip is the sum of the above four times:

[0090] t s =t a +t w +t ba+t bd =1.320 (s)

[0091] That is, it takes 1.32 seconds for the press to complete one forging and return to the top dead center from a stationary state, which meets general production needs.

[0092] like Figure 4 As shown, in this embodiment, a control method based on the above-mentioned servo forging press transmission system is also provided, comprising the following steps:

[0093] S1: The press enters the process from the standby state. At this time, the controller sends a standby command, making the crank angle equal to 0, the slider at the top dead center, and the motor speed equal to 0;

[0094] S2: The controller checks the user interface to see if there is a start command. If not, it returns to step S1 and remains in standby mode. If yes, it proceeds to the next step.

[0095] S3: Speed ​​control is performed, the crank rotates clockwise, and the target speed is equal to the preset speed n;

[0096] S4: During operation, the crank angle is continuously checked. If it has not exceeded 180 degrees (bottom dead center), step S3 is repeated, otherwise, the next step is performed;

[0097] S5: Check whether the operation mode of this cycle is continuous operation or single stroke mode. If it is continuous operation mode, return to step S3 and continue the speed control with the target speed equal to n. After the crank returns to 360 degrees (0 degrees), continue the next cycle. If it is single stroke mode, proceed to the next step;

[0098] S6: Speed ​​control is performed, the crank rotates clockwise to make the slider return, and the target speed is equal to n;

[0099] S7: Calculate in real time whether the angle difference between the current crank position and the top dead center position is less than or equal to the crank angle required for the servo motor to brake. If not, return to step S6 to continue speed control. Otherwise, return to step S1, the controller issues a standby command, so that the motor stops at the crank position of 0 degrees according to the preset deceleration. During the braking process, the flywheel kinetic energy is converted into electrical energy by the motor and temporarily stored in the energy storage capacitor through the servo controller. It can be reused for flywheel acceleration during the next forging to reduce electrical energy input.

[0100] During the continuous operation mode, if it is necessary to stop, the user can switch the operation mode to the single stroke mode at any time. The controller jumps out of the infinite loop in step S5 and stops.

[0101] Due to the use of a servo controller, the acceleration and deceleration process of the flywheel can be precisely controlled, achieving flexible speed change and accurate positioning, thereby reducing impact, delaying wear and extending service life.

[0102] Compare the method of the present invention with the existing patented method:

[0103] The existing patented technology does not use a flywheel, and the working pressure is completely provided by the electromagnetic torque of the motor. The motor needs to output the maximum torque at the nominal force stroke position. According to the dynamic model of the transmission system, the crank torque should reach 292kNm. Considering that its speed is 90rpm, the corresponding motor power is 3.06MW, which is 17 times more than the patented design. Correspondingly, the weight, volume and cost of the motor are also approximately the same multiple.

[0104] Compare the method of the present invention with a conventional non-servo forging press:

[0105] Conventional presses use ordinary asynchronous motors to drive the flywheel to rotate continuously. In order to prevent the motor speed from being too low and losing the driving torque, the flywheel speed cannot drop significantly at the end of each working stage, and generally cannot be lower than 95% of the no-load speed, that is, the parameter Rv = 0.95. This means that after each forging, only about 10% of the flywheel kinetic energy can be used to do work on the workpiece. To this end, the flywheel moment of inertia must reach Jce = 7128kg.m^2, which is 5.8 times that of the patented method. Because the patented method uses a servo motor, it can output maximum torque at any speed, allowing the flywheel to drop a lot after doing work, so that most of the energy can be released to do work, thereby significantly reducing the flywheel inertia. In the previous design example, Rv = 0.7 was used, that is, the flywheel speed dropped to 70% of the previous value after the working stage was completed, indicating that the remaining kinetic energy was 49%. In fact, Rv can be further reduced. If it is taken as 0.5, the remaining kinetic energy of the flywheel is 25%, and 75% of the kinetic energy is used for work. At this time, the required flywheel size can be further reduced.

[0106] The above is a specific description of the preferred implementation of the present invention, but the present invention is not limited to the described embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A servo forging press transmission system, characterized in that: It includes an energy storage mechanism, a control mechanism, a transmission mechanism, a flywheel and a working mechanism. The energy storage mechanism is electrically connected to the control mechanism, the control mechanism is electrically and data-connected to the transmission mechanism respectively, and the transmission mechanism is mechanically connected to the flywheel and the working mechanism.

2. A servo forging press transmission system according to claim 1, characterized in that: The energy storage mechanism is specifically an energy storage capacitor, and the control mechanism includes a servo controller, a press controller and a crankshaft encoder. The servo controller is bidirectionally electrically connected to the energy storage capacitor, the servo controller is bidirectionally data connected to the press controller, the crankshaft encoder is unidirectionally data connected to the press controller, and the crankshaft encoder is used to measure the crankshaft angle.

3. A servo forging press transmission system according to claim 2, characterized in that: The transmission mechanism comprises a servo motor, which is electrically connected to a servo controller. The servo motor is provided with a motor encoder, which is used to measure the position and speed of the servo motor rotor. The motor encoder is unidirectionally data-connected to the servo controller.

4. A servo forging press transmission system according to claim 3, characterized in that: The servo motor is provided with an output end, the output end is connected with a reduction mechanism, the reduction mechanism comprises a pinion and a gear, the pinion meshes with the gear, the pinion is connected to the output end of the servo motor, and the gear is coaxially connected to the flywheel.

5. A servo forging press transmission system according to claim 4, characterized in that: The large gear is provided with a crank, the crank is coaxially arranged with the large gear, and the end of the crank is connected with the working mechanism.

6. A servo forging press transmission system according to claim 5, characterized in that: The working mechanism includes a connecting rod, the top end of the connecting rod is connected to the crank, the bottom end of the connecting rod is connected to a slider, guide rails are arranged on both sides of the slider, the guide rails are arranged vertically, and the slider slides up and down along the extension direction of the guide rails, and a workbench is arranged at the bottom end of the guide rail without contact.

7. A control method for the servo forging press transmission system according to claim 1, characterized in that: The following steps are involved: S1: The press enters the process from the standby state. At this time, the controller sends a standby command, making the crank angle equal to 0, the slider at the top dead center, and the motor speed equal to 0; S2: The controller checks the user interface to see if there is a start command. If no command is sent, it returns to step S1 and remains in standby mode. If a command is sent, it executes the next step. S3: Speed ​​control is performed, the crank rotates clockwise and accelerates rapidly, and the target speed is equal to the preset speed n; S4: During the operation, the crank angle is continuously collected. If the angle does not exceed 180 degrees, step S3 is repeated, otherwise the next step is executed; S5: Check whether the operation mode of this cycle is continuous operation or single stroke mode: if it is continuous operation mode, return to step S3, continue the speed control with the target speed equal to n, and continue the next cycle after the crank returns to 360 degrees; If it is a single-trip mode, proceed to the next step; S6: Speed ​​control is performed, the crank rotates clockwise to make the slider return, and the target speed is equal to n; S7: Calculate in real time whether the angle difference between the current crank position and the top dead center position is less than or equal to the crank angle required for servo motor braking: If not, return to step S6 and continue speed control; otherwise return to step S1, the controller sends a standby command to make the motor stop at the crank position of 0 degrees according to the preset deceleration. During the stopping process, the servo controller commands the servo motor to operate in the power generation mode, and the generated electrical energy is temporarily stored in the energy storage mechanism.

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