Hub forging hydraulic press of plate frame type structure and operation method

Abstract

The invention relates to the field of hydraulic machines, in particular to a hub forging hydraulic machine of a plate-frame type structure and an operation method.The hub forging hydraulic machine of the plate-frame type structure comprises a plate-frame type machine body, oil cylinders, sliding blocks and a mounting rod, the oil cylinders are fixed to the middle of the plate-frame type machine body, the tops of the oil cylinders are connected through the mounting rod, and a driving and adjusting device is arranged at the top of the mounting rod; a piston rod at the bottom of the oil cylinder is in driving connection with the sliding block through a flange, and the plate frame type machine body comprises a first plate frame machine body and a second plate frame machine body. According to the hub forging hydraulic press of the plate frame type structure and the operation method, the rack, the oil cylinder and the movable cross beam are arranged, a channel is formed in the top of the rack, and the oil cylinder is fixedly installed in the channel through a hoist; a plurality of connecting plates are evenly and vertically arranged on the front portion and the rear portion of the channel and penetrate through the whole machine body, when the machine frame deforms during working, the frame plates can bear impact force in the hub forging process in the height direction, the structural strength is greatly improved, the structural stability is guaranteed, and use of the plate and frame type hydraulic machine is prolonged.

Description

Technical Field

[0001] This invention relates to the field of hydraulic presses, and more particularly to a plate-and-frame structure wheel hub forging hydraulic press and its operating method. Background Technology

[0002] In the current technology of large wheel hub forging, the hydraulic press needs to provide thousands of tons of forging pressure, and the frame needs to withstand the same amount of reaction force. In order to meet the requirements of stiffness (to prevent deformation and ensure wheel hub accuracy) and strength (to prevent fracture and ensure safety), the traditional frame can only be achieved by "increasing the amount of material used", which directly leads to excessive frame weight. This not only increases the difficulty of equipment transportation and installation, but also increases the cost of factory load-bearing design.

[0003] However, traditional heavy-duty frames are mostly integrally cast or welded structures, with large parts and complex shapes. To ensure structural integrity and mechanical performance, large processing equipment (such as heavy-duty milling machines) and complex processes (such as integral annealing to relieve stress) are required, resulting in complex frame manufacturing processes, long production cycles, high costs, and difficulty in quickly responding to customized production needs for different specifications of wheel hubs.

[0004] Wheel hub forging requires hydraulic presses with stable mold closing accuracy and pressure transmission efficiency. Traditional frames are heavy and have uneven rigidity distribution, which can easily lead to slight deformation after long-term use, resulting in pressure transmission deviations and affecting the uniformity of wheel hub wall thickness. At the same time, the fixed opening size of the integral frame makes it difficult to flexibly adjust to fit wheel hubs of different diameters and widths, resulting in poor product compatibility. Summary of the Invention

[0005] The purpose of this invention is to solve the problems existing in the prior art, and to propose a plate-frame structure wheel hub forging hydraulic press and operation method.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a plate-and-frame structure wheel hub forging hydraulic press, comprising a plate-and-frame body, a cylinder, a slider, and a mounting rod. The cylinder is fixed in the middle of the plate-and-frame body, and the top of the cylinder is connected via the mounting rod. A drive and adjustment device is provided at the top of the mounting rod. The piston rod at the bottom of the cylinder is drivenly connected to the slider via a flange. The plate-and-frame body comprises a first plate-and-frame body and a second plate-and-frame body. The cylinder is fixed in the middle of the first and second plate-and-frame bodies and connected via the mounting rod. Mounting grooves of the same structure are provided at the top of both the first and second plate-and-frame bodies.

[0007] Furthermore, the driving and adjusting device includes two adjusting blocks and a driving motor; the driving motor drives and connects the two adjusting blocks; the two ends of the two adjusting blocks are movably connected through mounting slot one and mounting slot two, respectively; the two adjusting blocks are fixed by a transverse connecting rod.

[0008] Furthermore, a detection feedback device is provided between the two adjusting blocks, with both ends of the detection feedback device fixed to the first plate frame body and the second plate frame body, respectively; the detection feedback device is located below the transverse connecting rod.

[0009] Furthermore, the hydraulic cylinder is connected to the adjusting block via two symmetrically arranged sets of mounting rods.

[0010] Furthermore, the tops of the two sets of mounting rods are connected to the adjusting block via threads.

[0011] Furthermore, the hydraulic cylinder is fixed to the plate frame body one and the plate frame body two respectively by top block one and top block two.

[0012] Furthermore, groove one and groove two are respectively provided at the two edges of the upper end face of the oil cylinder; the bottom of top block one is fixed to the oil cylinder through groove one; the bottom of top block two is fixed to the oil cylinder through groove two; protruding slot one and protruding slot two are respectively provided on the top of the frame-shaped frame of plate frame machine body one and plate frame machine body two.

[0013] Furthermore, the inner side of the top block one is fixed to the plate frame body one by a protruding slot one; the inner side of the top block two is fixed to the plate frame body two by a protruding slot two.

[0014] A method for operating a hydraulic press for forging a wheel hub using any of the above-mentioned plate-frame structures includes the following steps: S1. The detection feedback device emits a laser signal to the adjustment block; S2. The laser signal is reflected back to the detection feedback device from the surface of the adjustment block. The detection feedback device calculates the actual distance L of the adjustment block by calculating the round-trip time t of the laser and according to the formula L = (c×t) / 2; where c is the speed of light in air. S3. The system compares the calculated actual distance L with the pre-calibrated standard position distance L0 to obtain the position deviation: ΔL = L - L0; S4. The detection feedback device transmits the calculated position deviation ΔL signal to the drive adjustment device in real time. S5. After receiving the signal of the position deviation ΔL, the drive adjustment device calculates it using a PID control algorithm and outputs a control command. S6. According to the control command of the drive adjustment device, adjust the opening of the hydraulic valve; the change in the opening of the hydraulic valve controls the flow rate and direction of the hydraulic oil flowing into / out of the cylinder, thereby driving the cylinder to make fine-tuning movements to correct the position deviation.

[0015] Furthermore, the detection feedback device transmits the calculated real-time position deviation e(t) = ΔL(t) to the drive motor, and the drive motor calculates and outputs a signal for controlling the opening degree of the hydraulic valve according to the PID control algorithm shown below: Where u(t) is the control output of the drive and adjustment device, used to adjust the opening of the hydraulic valve; e(t) is the real-time position deviation, i.e., ΔL(t); k p k i， k d These are the proportional, integral, and derivative coefficients calibrated through testing; through the closed-loop control formed by the drive and adjustment device and the detection feedback device, the opening of the hydraulic valve is continuously adjusted so that the position of the oil cylinder continuously approaches the standard position until the absolute value of the position deviation ΔL is less than the set maximum allowable deviation A.

[0016] Compared with existing technologies, the advantages of this invention are: This invention provides a plate-frame structure wheel hub forging hydraulic press and its operating method. The press consists of a plate-frame body, hydraulic cylinders, and a slider. A channel for installing and adjusting the hydraulic cylinders is provided at the top of the plate-frame body. The hydraulic cylinders are fixedly installed in the channel by hoisting. Several connecting plates are evenly and vertically arranged at the front and back of the channel, extending through the entire plate-frame body. The top of the connecting plates is designed with hydraulic cylinder installation and adjustment steps. The hydraulic cylinders are fixed in their front and back positions by top blocks on both sides, improving cylinder precision. In this invention, when the plate-frame body deforms during operation, the multiple plates can withstand the impact force during the wheel hub forging process in the height direction, greatly improving structural strength, ensuring structural stability, and extending the service life of the plate-frame hydraulic press. Attached Figure Description

[0017] Figure 1 The three-dimensional structure of the wheel hub forging hydraulic press in this invention Figure 1 ; Figure 2 The three-dimensional structure of the wheel hub forging hydraulic press in this invention Figure 2 ; Figure 3 The three-dimensional structure of the wheel hub forging hydraulic press in this invention Figure 3 ; In the diagram: 1-Adjusting block; 2-Mounting rod; 5-Oil cylinder; 51-Groove one; 52-Groove two; 6-Slider; 7-Detection feedback device; 8-Drive motor; 11-Horizontal connecting rod; 31-Plate frame body one; 310-Protruding slot one; 311-Mounting slot one; 32-Plate frame body two; 320-Protruding slot two; 321-Mounting slot two; 41-Top block one; 42-Top block two. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1, please refer to the accompanying drawings in the instruction manual. Figures 1-3 As shown, a plate-and-frame structure wheel hub forging hydraulic press includes a plate-and-frame body, a hydraulic cylinder 5, a slider 6, and mounting rods 2. The hydraulic cylinder 5 is fixed in the middle of the plate-and-frame body, and its top is connected via the mounting rods 2. A drive and adjustment device is provided on the top of the mounting rods 2. The piston rod at the bottom of the hydraulic cylinder 5 is drivenly connected to the slider 6 via a flange. The plate-and-frame body includes a first plate-and-frame body 31 and a second plate-and-frame body 32. The hydraulic cylinder 5 is fixed in the middle of the first plate-and-frame body 31 and the second plate-and-frame body 32, and is connected to an adjustment block 1 via two symmetrically arranged sets of mounting rods 2. The tops of the two sets of mounting rods 2 are threadedly connected to the adjustment block 1. Mounting grooves 311 and 321 of the same structure are provided on the tops of both the first plate-and-frame body 31 and the second plate-and-frame body 32. In this embodiment, to ensure that the two plate-frame machine bodies and the hydraulic cylinder 5 are connected as a high-rigidity whole, a mounting rod 2 is provided on the top of the plate-frame machine body, and the slider 6 is located below the hydraulic cylinder 5. The piston rod at the bottom of the hydraulic cylinder 5 is driven to the top of the slider 6 through a flange. When the hydraulic cylinder 5 is working, the piston rod drives the slider 6 to move up and down along the guide rail (not shown in the figure) set in the plate-frame machine body, thereby forging and pressing the wheel hub blank placed below it. In addition, in this embodiment, a channel for installing and adjusting the hydraulic cylinder 5 is provided between the plate-frame machine body 31 and the second plate-frame machine body 32. The hydraulic cylinder 5 is hoisted and fixedly installed in the channel by the upper drive and adjustment device.

[0020] Example 2, based on Example 1 above, the driving and adjusting device includes two adjusting blocks 1 and a driving motor 8; the driving motor 8 drives and connects the two adjusting blocks 1; the two ends of the two adjusting blocks 1 are movably connected through mounting slot one 311 and mounting slot two 321 respectively; the two adjusting blocks 1 are fixed by a transverse connecting rod 11. In this example, mounting slot one 311 and mounting slot two 321 have a guiding function. The two adjusting blocks 1 are the actuating elements of this device. According to the actual situation, the driving motor 8 can drive the adjusting blocks 1 to move laterally in the mounting slot one 311 and mounting slot two 321 at the top, thereby driving the bottom oil cylinder 5 to move laterally, so that the oil cylinder 5 and the worktable surface meet the required specifications.

[0021] In Example 3, based on Example 2 above, a detection feedback device 7 is further provided between the two adjusting blocks 1. The two ends of the detection feedback device 7 are fixed to the first plate frame body 31 and the second plate frame body 32, respectively. The detection feedback device 7 is located below the transverse connecting rod 11. In this example, the detection feedback device 7 is used to detect the distance the two adjusting blocks 1 move in the first mounting slot 311 and the second mounting slot 321. When detecting the distance of movement, the two adjusting blocks 1 are regarded as a moving whole.

[0022] In Example 4, the hydraulic cylinder 5 is fixed to the plate frame machine body 31 and the plate frame machine body 32 respectively by top blocks 41 and 42. In this example, the front and rear positions of the hydraulic cylinder 5 are adjusted and fixed to the plate frame machine body 31 and the plate frame machine body 32 by top blocks 41 and 42. Changing the position of the hydraulic cylinder 5 by the position of top blocks 41 and 42 improves the accuracy. Specifically, grooves 51 and 52 are respectively provided on the two edges of the upper end face of the hydraulic cylinder 5; the bottom of the top block 41 is connected to the hydraulic cylinder 5. The cylinder 5 is fixed to the other side by a groove 51; the bottom of the top block 42 is fixed to the cylinder 5 by a groove 52; symmetrical protruding slots 310 and 320 are provided on the top of the frame of the first plate frame body 31 and the second plate frame body 32 respectively; the inner side of the top block 41 is fixed to the first plate frame body 31 by the protruding slot 310; the inner side of the top block 42 is fixed to the second plate frame body 32 by the protruding slot 320. The core of this embodiment is that the cylinder 5 is fixed and adjusted to the first plate frame body 31 and the second plate frame body 32 by the top blocks 41 and 42 respectively. The installation process of the cylinder 5 is as follows: On the upper end face of the hydraulic cylinder 5, near its two ends, groove 1 51 and groove 2 52 are respectively machined. These two grooves are preferably rectangular grooves or V-shaped grooves, which provide a reference for the positioning of the top block. In this embodiment, top block 1 41 and top block 2 42 are the core adjusting components of this embodiment. They have a symmetrical structure. The bottom of top block 1 41 has a protrusion or fitting part that matches groove 1 51 on the hydraulic cylinder 5, so that it can be accurately embedded and locked in groove 1 51. Similarly, the bottom of top block 2 42 is also fixed to groove 2 52 on the hydraulic cylinder 5 in the same way. This fitting structure can effectively prevent the hydraulic cylinder 5 from radially moving within the top block; and on the top of the inner plate frame of plate frame body 1 31 and plate frame body 2 32, protruding slot 1 310 and protruding slot 2 320 are respectively provided. These protruding slots can be regarded as slots or guide rails extending inward from the inside of the plate frame body, so that the inner end face of the top block 41 is close to and abuts against the protruding slot 310 of the plate frame body 31; similarly, the inner end face of the top block 42 is close to and abuts against the protruding slot 320 of the plate frame body 32.

[0023] The structure described above provides a simple, intuitive, and effective method for mechanical fine-tuning. Compared to adjusting the base of the entire plate frame body, precise calibration of the position of the hydraulic cylinder 5 can be achieved by adjusting only two top blocks, greatly simplifying the debugging work during installation and subsequent maintenance.

[0024] Example 5: A method for operating a hydraulic press for forging a wheel hub using any of the above-described plate-frame structures, comprising the following steps: S1. The detection feedback device 7 emits a laser signal to the adjustment block 1: After the system is started, the detection feedback device 7 (preferably a high-precision laser rangefinder sensor) installed on the plate frame body emits a modulated laser signal to a specific reflective surface of the adjustment block 1. S2. The laser signal is reflected back to the detection feedback device 7 from the surface of the adjustment block 1. The detection feedback device 7 calculates the actual distance L of the adjustment block 1 by calculating the round-trip time t of the laser, according to the formula L = (c×t) / 2; where c is the speed of light in air (approximately 3×10⁻⁶). 8 m / s); S3. The system compares the calculated actual distance L with the pre-calibrated standard position distance L0 to obtain the position deviation: ΔL = L - L0; where L0 is the distance from the detection feedback device 7 to the adjustment block 1 when the cylinder 5 is in the ideal working position. The sign and magnitude of ΔL directly reflect whether the current position of the cylinder 5 is "ahead" or "behind" the standard position and the amount of its deviation. S4. The detection feedback device 7 transmits the calculated position deviation ΔL signal to the drive motor 8 in real time: The detection feedback device 7 transmits the calculated position deviation ΔL to the drive motor 8 in real time through a fieldbus (such as PROFIBUS, EtherCAT) or analog signal line. In this embodiment, the drive motor 8 is an intelligent servo motor with an integrated controller, which directly receives the deviation signal. S5. After receiving the position deviation ΔL, the drive motor 8 calculates it using a PID control algorithm and outputs a control command. S6. According to the control command of the drive motor 8, the opening of the hydraulic valve is adjusted; the change in the opening of the hydraulic valve controls the flow rate and direction of the hydraulic oil flowing into / out of the oil cylinder 5, thereby driving the oil cylinder 5 to perform fine-tuning movements to correct the position deviation.

[0025] In Example 6, the detection feedback device 7 transmits the calculated real-time position deviation e(t) = ∆L(t) to the drive motor 8. The drive motor 8 calculates and outputs a signal for controlling the opening degree of the hydraulic valve according to the PID control algorithm shown below: Where u(t) is the control output of the drive and adjustment device 8, used to adjust the opening of the hydraulic valve; e(t) is the real-time position deviation, i.e. ΔL(t); k p k i， k d These are the proportional, integral, and derivative coefficients calibrated through testing, respectively. Through the closed-loop control formed by the drive and adjustment device 8 and the detection feedback device 7, the opening of the hydraulic valve is continuously adjusted so that the position of the oil cylinder 5 continuously approaches the standard position until the absolute value of the position deviation ΔL is less than the set maximum allowable deviation A.

[0026] Based on the above embodiments, as a supplement to the embodiments, and through a calculation with specific numerical values, the complete process from laser ranging to PID control output is illustrated in detail: System preset parameters 1. Set the standard position distance (L0) to 1000.00mm (this is the distance from the detection device to the adjusting block 1 when the hydraulic cylinder 5 is in the ideal working position); Set the maximum permissible deviation (A): ±0.10mm; PID control parameters (calibrated by test): Set the scaling factor K P 50.0; Set the integral coefficient K i : 2.0; Set the differential coefficient K d 0.5; Control cycle T: 0.01s (the system samples, calculates, and outputs every 10 milliseconds); 2. Real-time detection and deviation calculation (steps S1-S3) In S1-S2: During a certain control cycle, the detection feedback device 7 emits and receives laser light, and the round-trip time of the laser light is measured to be t = 6.673 × 10⁻⁶. -9 Second, the speed of light in air, c, is approximately 3 × 10⁻⁶. 8 m / s, Distance calculation: ; S3: Deviation Analysis ; The calculated real-time position deviation is e(t) = ΔL(t) = +0.95mm. This deviation indicates that the current position of cylinder 5 is "ahead" of the standard position by 0.95mm, which is far beyond the allowable range (A = ±0.10mm) and needs to be corrected.

[0027] 3. PID control algorithm calculation (steps S4-S5) The controller of drive motor 8 receives a deviation signal of e(t) = +0.95mm. We assume that the system has been running for a while before this control cycle and has the following historical data (in digital control, integrals and derivatives are calculated through discretization): Previous error: e(t-1) = +1.0 mm Integral term of error (approximately cumulative sum): (This is an assumed value, representing the cumulative deviation from previous values) The derivative of the error (approximately the difference between the current and previous errors): , Now, the controller performs PID calculations: , Calculation Interpretation: Proportional term (47.5): Generates a strong correction signal that is proportional to the current deviation, which is the main force for real-time correction. Integral term (10.0): Due to the accumulation of positive deviations in the past, this term outputs a positive signal to further strengthen the correction and completely eliminate the steady-state error; Differential term (-2.5): Since the error is smaller than the previous one (the deviation is decreasing), this term outputs a negative signal, which acts as a brake to prevent the system from overshooting the target position due to overcorrection, thereby suppressing overshoot and making the adjustment process smoother. The final control output u(t) = 55.0. This value is a dimensionless control quantity, corresponding to the speed, direction, or number of pulses of the drive motor 8, which will ultimately be converted into a specific opening degree of the hydraulic valve.

[0028] 4. Execution and System Response (Step S6) According to the control command u(t)=55.0, the drive motor 8 drives the hydraulic valve (such as an electro-hydraulic proportional valve) to increase its opening, thereby controlling more hydraulic oil to flow into the corresponding chamber of the cylinder 5, and driving the cylinder 5 to make a fine adjustment movement backward (towards the "lag" direction) to eliminate the deviation of +0.95mm.

[0029] 5. Closed-loop convergence In the next and subsequent control cycles (every 0.01 seconds), the entire process from S1 to S6 will be repeated continuously. Due to the intelligent adjustment of the controller, the position of cylinder 5 will dynamically and smoothly converge towards the standard position (L0). After several cycles of adjustment, the absolute value of the position deviation ΔL will gradually decrease until the accuracy requirement of |ΔL| < A = 0.10 mm is met, and the system then enters a dynamic maintenance state.

[0030] The beneficial effects demonstrated in the above embodiments show the high precision of laser ranging, which can detect sub-millimeter-level position changes; the effectiveness of the PID algorithm, through the synergistic effect of three factors, not only can it quickly respond to deviations (proportional term), but it can also completely eliminate deviations (integral term) and ensure a smooth process.

[0031] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A plate-frame structure wheel hub forging hydraulic press, comprising a plate-frame body, a cylinder (5), a slider (6), and a mounting rod (2), wherein the cylinder (5) is fixed in the middle of the plate-frame body, the top of the cylinder (5) is connected via the mounting rod (2), a driving and adjusting device is provided on the top of the mounting rod (2), and the piston rod at the bottom of the cylinder (5) is drivenly connected to the slider (6) via a flange, characterized in that, The plate frame body includes a plate frame body one (31) and a plate frame body two (32). The oil cylinder (5) is fixed in the middle of the plate frame body one (31) and the plate frame body two (32) and is connected by a mounting rod (2). The top of the plate frame body one (31) and the plate frame body two (32) are provided with mounting groove one (311) and mounting groove two (321) with the same structure.

2. The wheel hub forging hydraulic press with a plate-frame structure according to claim 1, characterized in that: The driving and adjusting device includes two adjusting blocks (1) and a driving motor (8); the driving motor (8) drives and connects the two adjusting blocks (1). The two ends of the two adjustment blocks (1) are movably connected by mounting slot one (311) and mounting slot two (321) respectively; the two adjustment blocks (1) are fixed by a transverse connecting rod (11).

3. The wheel hub forging hydraulic press with a plate-frame structure according to claim 2, characterized in that: A detection feedback device (7) is also provided between the two adjustment blocks (1). The two ends of the detection feedback device (7) are fixed to the first plate frame body (31) and the second plate frame body (32) respectively. The detection feedback device (7) is located below the transverse connecting rod (11).

4. The wheel hub forging hydraulic press with a plate-frame structure according to claim 1, characterized in that: The hydraulic cylinder (5) is connected to the adjusting block (1) through two sets of symmetrically arranged mounting rods (2).

5. A plate-frame type hydraulic press for wheel hub forging according to claim 4, characterized in that: The tops of the two sets of mounting rods (2) are connected to the adjusting block (1) by threads.

6. A plate-frame type hydraulic press for wheel hub forging according to claim 1, characterized in that: The oil cylinder (5) is fixed to the plate frame body one (31) and plate frame body two (32) respectively by top block one (41) and top block two (42).

7. A plate-frame type hydraulic press for wheel hub forging according to claim 6, characterized in that: Groove 1 (51) and groove 2 (52) are respectively provided on the two edges of the upper end face of the oil cylinder (5); the bottom of the top block 1 (41) is fixed to the oil cylinder (5) through groove 1 (51); the bottom of the top block 2 (42) is fixed to the oil cylinder (5) through groove 2 (52); protruding slot 1 (310) and protruding slot 2 (320) are respectively provided on the top of the frame-shaped frame of the plate frame body 1 (31) and the plate frame body 2 (32).

8. A plate-frame type hydraulic press for wheel hub forging according to claim 7, characterized in that: The inner side of the top block one (41) is fixed by the protruding slot one (310) and the plate frame body one (31); the inner side of the top block two (42) is fixed by the protruding slot two (320) and the plate frame body two (32).

9. A method for operating a hydraulic press for forging a wheel hub using a plate-frame structure according to any one of claims 1-8, characterized in that, Includes the following steps: S1. The detection feedback device (7) emits a laser signal to the regulating block (1); S2. The laser signal is reflected from the surface of the adjustment block (1) back to the detection feedback device (7). The detection feedback device (7) calculates the actual distance L of the adjustment block (1) by calculating the round-trip time t of the laser and according to the formula L = (c × t) / 2; where c is the speed of light in air. S3. The system compares the calculated actual distance L with the pre-calibrated standard position distance L0 to obtain the position deviation: ΔL = L - L0; S4. The detection feedback device (7) transmits the calculated position deviation ΔL signal to the drive motor (8) in real time. S5. After receiving the signal of the position deviation ΔL, the drive motor (8) uses the PID control algorithm to calculate and outputs a control command. S6. According to the control command of the drive motor (8), adjust the opening of the hydraulic valve; the change in the opening of the hydraulic valve controls the flow rate and direction of the hydraulic oil flowing into / out of the oil cylinder (5), thereby driving the oil cylinder (5) to make fine adjustments to correct the position deviation.

10. The method for operating a hydraulic press for forging wheel hubs with a plate-frame structure according to claim 9, characterized in that: The detection feedback device (7) transmits the calculated real-time position deviation e(t)=ΔL(t) to the drive motor (8), and the drive motor (8) calculates and outputs a signal for controlling the opening degree of the hydraulic valve according to the PID control algorithm shown below: , where u(t) is the control output of the drive and adjustment device (8), used to adjust the opening of the hydraulic valve; e(t) is the real-time position deviation, i.e. ΔL(t); k p k i， k d : These are the proportional, integral, and differential coefficients calibrated through testing; through the closed-loop control formed by the drive and adjustment device (8) and the detection feedback device (7), the opening of the hydraulic valve is continuously adjusted so that the position of the oil cylinder (5) continuously approaches the standard position until the absolute value of the position deviation ΔL is less than the set maximum allowable deviation A.

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