A ram deflection compensation system and method based on double-screw rod load rate of change

Abstract

The present application relates to a kind of based on the deflection compensation system of ram load variation of double screw rod comprising servo motor and the ball screw of driving spindle box movement;Ram and the hydraulic pull rod mounted on ram and the hydraulic cylinder of control hydraulic pull rod;Electro-hydraulic proportional valve and PLC analog output module of control hydraulic cylinder;Numerical control system and drive module of control servo motor movement.Based on the deflection compensation method of ram load variation of double screw rod, ram moves in spindle box automatically monitors the current variation of spindle box servo motor, according to the vertical direction deviation change of current variation reflecting the deflection of ram is generated, after function calculation in the embedded numerical control system, the opening size of valve core of electro-hydraulic proportional valve is controlled by PLC analog output voltage signal, control input to hydraulic cylinder pressure, through the hydraulic cylinder control hydraulic pull rod to ram exerting reverse torque to compensate the deflection of ram.The present application method is simple, can realize automatic compensation, reaction is fast, can satisfy the precision requirement of double screw rod middle type numerical control milling and boring machine.

Description

TECHNICAL FIELD

[0001] The present application relates to a ram deflection compensation method, in particular to a ram deflection compensation system and method based on double screw rod load change. BACKGROUND

[0002] At present, the main shaft box of the positive hanging type numerical control floor type milling and boring machine is arranged between the door frame type columns, and adopts front and rear double screw rod transmission, and the whole has good symmetry and stability. The double screw rods arranged in front and rear can be adjusted in real time by the numerical control system, so that the balance compensation function of the horizontal angle of the main shaft box is realized, so as to eliminate the inclination caused by the change of the gravity center of the main shaft box due to the movement of the ram. However, during the movement of the ram, a certain position deviation in the vertical direction will be caused due to elastic deformation, and this deviation will affect the machining accuracy of the machine tool. At present, a manual measurement of the ram deflection deviation is widely used, and then the adjustment is carried out. The method has low automation degree, and a large amount of time is consumed for multiple adjustments. SUMMARY

[0003] The present application aims at the deficiencies in the prior art, and provides a ram deflection compensation system and method based on the load change rate of double screw rod motors during the movement of the ram of the positive hanging type numerical control floor type milling and boring machine. The machine tool does not need manual measurement, and the ram deflection automatic compensation control is realized quickly by calculating the load change of the screw rod servo motor.

[0004] In order to realize the above technical purpose, the present application provides the following scheme.

[0005] A ram deflection compensation system based on double screw rod load change, comprising a numerical control system, a servo motor one, a servo motor two, a driving module, a PLC analog output module, an electro-hydraulic proportional valve, a ball screw nut pair one, a ball screw nut pair two, a main shaft box, a ram and a hydraulic oil cylinder. The servo motor one and the servo motor two are connected with the ball screw of the ball screw nut pair one and the ball screw nut pair two through a transmission mechanism respectively, the servo motor drives the ball screw to rotate to drive the nut of the ball screw nut pair to move up and down on the ball screw, and the nut is fixed with the main shaft box to drive the main shaft box to move up and down along the ball screw. The ram is arranged in the main shaft box in a horizontal moving mode, two hydraulic pull rods are arranged on the upper part of the ram and are in transmission connection with the two hydraulic oil cylinders respectively, the front end of the hydraulic pull rod is fixedly connected with the front end of the ram, and the rear end of the hydraulic pull rod is connected with the tail part of the ram through the hydraulic oil cylinder; the oil inlet of the hydraulic oil cylinder is connected with the electro-hydraulic proportional valve; the voltage output end of the PLC analog module is connected with the voltage input end of the electro-hydraulic proportional valve, the PLC analog module outputs 0-10V voltage and the electro-hydraulic proportional valve, the opening size of the valve core of the electro-hydraulic proportional valve is controlled through the voltage, the adjustment of the output oil pressure of the proportional valve is realized, and then the adjustment of the oil inlet pressure of the hydraulic oil cylinder is realized.

[0006] The function calculation module in the numerical control system divides the ram stroke into n intervals, n is a natural number greater than 1, and the current change rate ΔI of the servo motor at position j when the ram moves in each interval i is calculated ij :

[0007] ΔI ij = (ΔI1 ij + ΔI2 ij ) / 2 = (I1 ij - I1 i-1 + I2 ij - I2 i-1 ) / 2,

[0008] In the formula, I1 ij is the current of the servo motor one at any position j in the interval i, I2 ij is the current of the servo motor two at any position j in the interval i, I1 i-1 is the current of the servo motor one when the ram moves to the starting point of the interval i, I2 i-1 is the current of the servo motor two when the ram moves to the starting point of the interval i, i = 1 ~ n.

[0009] According to the current change rate ΔI ij , the output voltage V ij of the PLC analog quantity module is calculated:

[0010] V ij = k i ΔI ij + E i ,

[0011] In the formula, E i is the voltage output correction value in the interval i, which is adjusted in actual detection accuracy.

[0012] V ij is the PLC analog output voltage at any position j in the interval i, k i is the slope in the interval i, which is obtained by computer simulation. The deflection curve of the ram is calculated by computer simulation, and the reverse torque N is also calculated by simulation. The cross-sectional area S of the oil cylinder is fixed, and the pressure P in the oil cylinder can be calculated according to N = PS. The pressure P is controlled by an electro-hydraulic proportional valve, and the electro-hydraulic proportional valve controls the oil pressure through an analog voltage of 0-10V. Therefore, the analog voltage V of the proportional valve is determined in this way, and the current I is calculated by the system. Therefore, K can be calculated, and E is the actual application error correction value.

[0013] The present application also provides a ram deflection compensation method based on double screw rod load change, comprising a numerical control system, a driving module, a servo motor, a ball screw, a ram, a hydraulic oil cylinder, a hydraulic pull rod, a PLC analog output module, an electro-hydraulic proportional valve, the numerical control system and the driving module control the servo motor, the numerical control system directly reads the load change of the screw servo motor when the ram moves; after function calculation, the voltage signal is output to the electro-hydraulic proportional valve through the PLC analog output module, the electro-hydraulic proportional valve controls the pressure entering the hydraulic oil cylinder, the pressure of the oil cylinder is transmitted to the hydraulic pull rod to exert a reverse torque on the ram, and the deflection of the ram is compensated:

[0014] 1) The load change of the ball screw causes the load change of the servo motor, and the driving module detects the load current value of the servo motor;

[0015] 2) The numerical control system directly reads the load current of the driving module;

[0016] 3) The ram stroke is divided into n intervals, n is a natural number greater than 1, and the current change rate of the servo motor when the ram moves in each interval is calculated;

[0017] 4) The output voltage of the PLC analog module when the ram moves in each interval is calculated according to the current change rate;

[0018] 5) The PLC analog module inputs the output voltage to the electro-hydraulic proportional valve;

[0019] 6) The electro-hydraulic proportional valve controls the oil inlet pressure of the hydraulic oil cylinder according to the input voltage value;

[0020] 7) The hydraulic oil cylinder drives the hydraulic pull rod to generate a reaction torque on the ram;

[0021] 8) Deflection compensation is completed.

[0022] The input voltage of the electro-hydraulic proportional valve is direct current 0-10V, which is converted into direct current 0-10V analog quantity by D / A conversion of the PLC analog output module;

[0023] The current change rate of the servo motor when the ram is at position j in each interval i is ΔI ij Determined by the following formula

[0024] ΔI ij =(ΔI1 ij +ΔI2 ij ) / 2=( I1 ij -I1 i-1 +I2 ij -I2 i-1 ) / 2,

[0025] In the formula, I1 ijLet I2 be the current of a servo motor at any position j within interval i. ij Let I1 be the current of servo motor II at any position j within interval i. i-1 I2 is the current of servo motor 1 when the ram moves to the starting point of interval i. i-1 Let be the current of servo motor 2 when the ram moves to the starting point of interval i, where i = 1 to n.

[0026] The input voltage of the electro-hydraulic proportional valve is DC 0-10V. The PLC analog output module converts the digital signal calculated by the CNC system into a DC 0-10V analog signal via a D / A converter. The PLC analog output voltage V is calculated as follows: when the slide moves in each interval i, the PLC analog output voltage V is... ij The voltage V at point j in interval i ij With ΔI ij There exists a certain proportion k i ;

[0027] V ij =k i ΔI ij +E i ,

[0028] In the formula E i This is the voltage output correction value for interval i, which is adjusted based on actual detection accuracy.

[0029] K i For V ij The slope in interval i is obtained through computer simulation.

[0030] The movement of the slide block occurs within the spindle box, and the slide block moves in a linear sliding manner.

[0031] The spindle box is centrally located and uses a double lead screw drive. This allows the spindle box's center of gravity to shift as the slide moves, but the double lead screws maintain the spindle box's balance under load.

[0032] The load current of the servo motor is detected by the servo drive.

[0033] The load change rate of the servo motor is calculated by the CNC system. The output voltage is automatically determined by a function formula embedded in the system.

[0034] This invention discloses a method for compensating for ram deflection under varying loads of a dual-screw system. It employs a CNC system to read the current value of the screw servo motor in real time, calculates the current change rate, establishes a mathematical model, and controls a hydraulic cylinder to apply a reverse torque to compensate for ram deflection. The mathematical function of this invention is embedded into the control system, forming a system that automatically acquires and compensates for ram deflection under varying loads of the dual-screw system. This system includes a CNC system, a servo motor, a PLC analog output module, an electro-hydraulic proportional valve, a hydraulic cylinder, and a connecting rod. When the ram extends or retracts during operation, the mathematical function embedded in the system calculates and outputs analog data at any position to automatically compensate for ram deflection.

[0035] This invention offers a simple, automatic compensation method. Its principle is straightforward and low-cost. Utilizing the servo motor current changes detected by the machine tool's CNC system, it automatically calculates ram deflection compensation, significantly improving the reliability, safety, and accuracy maintenance of the machine tool. Through this automatic ram deflection compensation method, the quality of machined parts can be improved. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the ram deflection compensation device for load variation of the dual lead screw according to the present invention.

[0037] Figure 2 This is a schematic diagram of the slide hydraulic cylinder and tie rod device of the present invention.

[0038] Figure 3 This is the electrical wiring diagram for the slide deflection compensation method under varying loads of the dual lead screws according to the present invention. Implementation

[0039] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments, but these embodiments should not be construed as limiting the present invention.

[0040] like Figure 1As shown, this embodiment of the invention provides a ram deflection compensation method applicable to a positive-mounted double-screw CNC boring machine. It includes: a servo motor 1 (servo motor one, servo motor two), a ball screw nut assembly 2 (ball screw nut assembly one, ball screw nut assembly two), a spindle box 3, a ram 4, a hydraulic tie rod 5, and a hydraulic cylinder 6. Servo motor one and servo motor two are respectively connected to the ball screws of ball screw nut assembly one and ball screw nut assembly two via reducers. Servo motor 1 drives the ball screw to rotate, causing the nut to move up and down on the screw. The nut is fixed to the spindle box, thereby driving the spindle box to move up and down along the ball screw. The slide is horizontally mounted inside the spindle box. Two hydraulic rods are mounted on the upper part of the slide. The front ends of the hydraulic rods are fixedly connected to the front end of the slide and are driven by a hydraulic cylinder. The rear ends of the hydraulic rods are connected to the tail end of the slide via the hydraulic cylinder. The oil inlet of the hydraulic cylinder is connected to an electro-hydraulic proportional valve. The voltage output terminal of the PLC analog module is connected to the voltage input terminal of the electro-hydraulic proportional valve. The PLC analog module outputs a 0-10V voltage to the electro-hydraulic proportional valve. By controlling the voltage, the valve core opening of the electro-hydraulic proportional valve is adjusted, thereby adjusting the output oil pressure of the proportional valve and thus the oil inlet pressure of the hydraulic cylinder.

[0041] Among them, the movement of the slide block 4 within the spindle box 3 will cause a change in the center of gravity, which in turn causes a change in the force on the lead screw 2, directly affecting the change in the current of the servo motor 1.

[0042] like Figure 2 As shown in the figure, this embodiment of the invention provides a ram deflection compensation method using a ram hydraulic cylinder and a tie rod device. It includes: a ram 4, a hydraulic tie rod 5, and a hydraulic cylinder 6.

[0043] Specifically, the upper part of the slide ram 4 is equipped with two hydraulic tie rods 5, and two hydraulic cylinders 6 are connected to the hydraulic tie rods 5 at the tail of the slide ram 4. By pulling the hydraulic tie rods 5 through the hydraulic cylinders 6, a reverse deformation torque is applied to the slide ram 4, increasing the stiffness of the slide ram to compensate for the deflection of the extended slide ram.

[0044] like Figure 3 As shown, an embodiment of the present invention provides an electrical wiring diagram for a ram deflection compensation method, including: a numerical control system 7, a drive module 8, a PLC analog output module 9, a servo motor 1, and an electro-hydraulic proportional valve 10.

[0045] Among them: the current of servo motor 1 is monitored by drive module 8 and can be automatically read by CNC system 7. The calculation function embedded in CNC system 7 calculates the compensation voltage value required for slide at any position. Then, the voltage value is output to electro-hydraulic proportional valve 10 through PLC analog output module 9. Electro-hydraulic proportional valve controls hydraulic cylinder.

[0046] The reverse moment of force given to the ram is related to the position of the ram, the ram is divided into a plurality of different position intervals, different compensation characteristic curve functions are established in each interval. The position (P1, P2, P3) and the corresponding compensation function (N1, N2, N3) at the position are saved in the system. When the ram is running, the corresponding compensation program is automatically run according to the position of the ram.

[0047] The hydraulic proportional valve is controlled by the PLC analog output module, the system calculates the compensation value and outputs the analog output module of the PLC after function operation, the analog output module outputs 0-10V voltage through D / A conversion, and the flow of the valve core of the proportional valve is controlled through the voltage. Finally, the pressure of the hydraulic cylinder is controlled.

[0048] The present application is a kind of based on the deflection compensation method of ram of double screw rod load change, the compensation device constitutes includes: servo motor and ball screw;Ram, hydraulic pull rod and hydraulic cylinder;Numerical control system and drive module for controlling servo motor;PLC analog module and proportional solenoid valve for controlling hydraulic cylinder. The compensation method comprises the following steps:

[0049] (1) When the ram is stretched, a certain deflection will be generated due to its own weight, which will generate a certain position deviation ΔY in the Y-axis direction.

[0050] (2) Two hydraulic pull rods are arranged above the ram to generate an upward reverse moment N of force to compensate for the deflection of the ram due to its own weight, so as to reduce or eliminate ΔY.

[0051] (3) The pressure of the hydraulic cylinder is controlled by the PLC, and the hydraulic pull rod generates torque by the hydraulic cylinder;

[0052] (4) The position stroke of the ram is divided into n regions;The value of n can be selected according to the stroke of the ram, and n is usually selected within 6-15;

[0053] (4-1) The starting position of each region i is P i-1 ; i=1~n;

[0054] (4-2) The end position of each region i is P i ;

[0055] (4-3) Each interval is recorded as P i P i-1 ;

[0056] (4-4) The reverse moment N i of the ram in the interval P i P i-1 corresponds to;

[0057] (5) The center of gravity of the spindle box will change when the slide moves, which will cause the force on the lead screws at the front and rear of the spindle box to change. This force change will affect the current of the servo motor.

[0058] (5-1) The longer the slide extends, the greater the change in the center of gravity, the greater the change in the lead screw current, and the greater the reverse torque that needs to be applied to the slide.

[0059] (5-2) The current of the front lead screw servo motor at any position j in interval i is denoted as I1. ij P for each interval i i-1 The point current is I1 i-1 Interval P i P i-1 The rate of change of current at point j is denoted as ΔI1. ij ,ΔI1 ij = I1 ij -I1 i-1 ;

[0060] (5-3) The current of the rear lead screw servo motor at any position j in interval i is denoted as I2. ij P for each interval i i-1 The point current is I2 i-1 Interval P i P i-1 The rate of change of current is denoted as ΔI² ij ΔI2 ij = I2 ij -I2 i-1 ;

[0061] (5-4) Interval P i P i-1 The average rate of change of the current of the front and rear lead screw servo motors is denoted as ΔI. ij ;

[0062] ΔI ij =(ΔI1 ij +ΔI2 ij ) / 2=(I1) ij -I1 i-1 +I2 ij -I2 i-1 ) / 2

[0063] (6) Calculate interval P i P i-1 PLC analog output voltage V ij ;

[0064] (6-1) The reverse torque of the hydraulic tie rod is controlled by the hydraulic cylinder. When the input pressure of the hydraulic cylinder increases, the applied reverse torque increases; when the input pressure of the hydraulic cylinder decreases, the applied reverse torque decreases.

[0065] (6-2) The input pressure of the hydraulic cylinder is controlled by an electro-hydraulic proportional valve. When the input voltage of the proportional valve increases, the input pressure of the hydraulic cylinder increases; when the input voltage of the proportional valve decreases, the input pressure of the hydraulic cylinder decreases.

[0066] (6-3) The input voltage of the electro-hydraulic proportional valve is DC 0-10V, which is controlled by the PLC analog output module;

[0067] (6-4) The PLC analog output module converts the digital signal calculated by the system into a DC 0-10V analog signal through D / A conversion;

[0068] (6-5) Calculate interval P i P i-1 The PLC analog output voltage V at any position j ij This allows control of the reverse torque N of the hydraulic tie rod. ij ;

[0069] (7) Through ΔI ij Calculate interval P i P i-1 The PLC analog output voltage V at any position j ij ;

[0070] (7-1) In the interval P i P i-1 Voltage V ij With ΔI ij There exists a certain proportion k i ;

[0071] (7-2) In the interval P i P i-1 The voltage output has a correction value E i ;

[0072] (7-3) Calculate the PLC output voltage

[0073] V ij =k i ΔI ij +E i

[0074] In the above technical solution, the current of the lead screw servo motor is obtained by directly reading the servo motor drive current parameter value through the CNC system.

[0075] In the above technical solution, the movement of the slide is linear. Example

[0076] Taking our company's HBA6913 as an example, the ram stroke is 800mm, divided into 8 intervals, each interval having a stroke of 100mm. The diameter of the hydraulic cylinder of the pull rod is 5cm. Taking the second interval as an example:

[0077] V 2j =k2ΔI 2j +E2

[0078] ΔI 2j =(ΔI1 2j +ΔI2 2j ) / 2=( I1 2j -I11+I2 2j -I21) / 2

[0079] Among them: I1 2j Let be the current of servo motor 1 at any point j in the second interval;

[0080] I11 is the current of servo motor 1 at the starting point 100mm of the second interval;

[0081] I2 2j Let be the current of servo motor 2 at any point j in the second interval;

[0082] I12 is the current of servo motor 2 at the starting point 100mm of the second interval;

[0083] K2 is the proportion of interval 2, and its value in practical applications is 4.6;

[0084] E2 is the error correction value of 0.2 for interval 2 during the actual accuracy test of the slide block;

[0085] The same applies to other intervals.

[0086] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

[0087] Finally, it should be noted that the above embodiments are merely representative examples of the present invention. Obviously, the present invention is not limited to the above embodiments and can have many variations. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention should be considered to fall within the protection scope of the present invention.

Claims

1. A double-screw rod load change-based ram deflection compensation system, comprising a numerical control system, a servo motor one, a servo motor two, a drive module, a PLC analog output module, an electro-hydraulic proportional valve, a ball screw nut pair one, a ball screw nut pair two, a spindle box, a ram, and a hydraulic cylinder; the servo motor one and the servo motor two are respectively connected with the ball screws of the ball screw nut pair one and the ball screw nut pair two through transmission mechanisms, the nuts of the ball screw nut pair one and the ball screw nut pair two are fixed with the spindle box to drive the spindle box to move up and down along the ball screws; the ram is arranged in the spindle box in a horizontal moving manner, two hydraulic pull rods are arranged on the upper part of the ram and are respectively in transmission connection with the two hydraulic cylinders, the front ends of the hydraulic pull rods are fixedly connected with the front end of the ram, and the rear ends of the hydraulic pull rods are connected with the tail part of the ram through the hydraulic cylinders; the oil inlet of the hydraulic cylinder is connected with the electro-hydraulic proportional valve; the voltage output end of the PLC analog module is connected with the voltage input end of the electro-hydraulic proportional valve, the PLC analog module outputs a voltage of 0-10V to the electro-hydraulic proportional valve, the opening size of the valve core of the electro-hydraulic proportional valve is controlled through the voltage, the adjustment of the output oil pressure of the proportional valve is realized, and thus the adjustment of the oil inlet pressure of the hydraulic cylinder is realized; the numerical control system is embedded with a function calculation module, the function calculation module divides the stroke of the ram into n intervals, n is a natural number greater than 1, and the current change rate ΔI of the servo motor at j when the ram moves in each interval i is calculated ij : ΔI ij = (ΔI1 ij + ΔI2 ij ) / 2 = (I1 ij - I1 i-1 + I2 ij - I2 i-1 ) / 2 wherein I1 ij is the current of the first servo motor at an arbitrary position j in the interval i, I2 ij is the current of the second servo motor at an arbitrary position j in the interval i, I1 i-1 is the current of the first servo motor at the start of the movement of the ram to the interval i, I2 i-1 is the current of the second servo motor at the start of the movement of the ram to the interval i, i = 1 ~ n; According to the current rate of change ΔI ij The output voltage V of the PLC analog quantity module at j in each interval i is calculated ij : V ij =k i ΔI ij +E i , wherein E i is the voltage output correction value in the interval i, adjusted at the actual detection accuracy; V ij PLC analog output voltage at interval i, j i Slope at interval i, determined by computer simulation.

2. A method for compensating the deflection of a ram based on the load change of double screw rods, comprising a numerical control system, a servo motor 1, a servo motor 2, a driving module, a PLC analog output module, an electro-hydraulic proportional valve, a ball screw nut pair 1, a ball screw nut pair 2, a spindle box, a ram, and a hydraulic cylinder; the servo motor 1 and the servo motor 2 are connected with the ball screws of the ball screw nut pair 1 and the ball screw nut pair 2 through transmission mechanisms, and the nuts of the ball screw nut pair 1 and the ball screw nut pair 2 are fixed with the spindle box so as to drive the spindle box to move up and down along the ball screws; the ram is arranged in the spindle box in a horizontal moving manner, and two hydraulic pull rods are arranged on the upper part of the ram and are in transmission connection with the two hydraulic cylinders respectively, the front ends of the hydraulic pull rods are fixedly connected with the front end of the ram, and the rear ends of the hydraulic pull rods are connected with the tail part of the ram through the hydraulic cylinders; the oil inlet of the hydraulic cylinder is connected with the electro-hydraulic proportional valve; the voltage output end of the PLC analog module is connected with the voltage input end of the electro-hydraulic proportional valve; the numerical control system directly reads the load change of the screw servo motor when the ram moves; after function calculation, the voltage signal is output to the electro-hydraulic proportional valve through the PLC analog output module, the pressure entering the hydraulic cylinder is controlled by the electro-hydraulic proportional valve, the pressure of the hydraulic cylinder is transmitted to the hydraulic pull rod to exert a reverse torque on the ram, and the deflection of the ram is compensated: 1) the load change of the servo motor caused by the force change of the ball screw rod is detected by the driving module; 2) the load current of the driving module is directly read by the numerical control system; 3) the stroke of the ram is divided into n intervals, n is a natural number greater than 1, and the current change rate of the servo motor when the ram moves in each interval is calculated; The rate of change of current ΔI of the j servo motor when the ram moves in each interval i ij Is determined by calculation from the formula ΔI ij = (ΔI1 ij + ΔI2 ij ) / 2 = (I1 ij - I1 i-1 + I2 ij - I2 i-1 ) / 2, wherein I1 ij is the current of servo motor one at an arbitrary position j in interval i, I2 ij is the current of servo motor two at an arbitrary position j in interval i, I1 i-1 is the current of servo motor one at the start of interval i, I2 i-1 is the current of servo motor two at the start of interval i, i = 1 ~ n; 4) the output voltage of the PLC analog module when the ram moves in each interval is calculated according to the current change rate; The input voltage of the electro-hydraulic proportional valve is DC 0-10V. The PLC analog output module converts the digital signal calculated by the CNC system into a DC 0-10V analog signal via a D / A converter. The PLC analog output voltage V at point j when the slide moves in each interval i is calculated using the following formula. ij In the interval i, the voltage V ij With ΔI ij There exists a certain proportion k i ; V ij =k i ΔI ij +E i , wherein E i is the voltage output correction value in the interval i, adjusted at the actual detection accuracy; k i for V ij The slope of the interval i is calculated by computer simulation; 5) the output voltage of the PLC analog module is input to the electro-hydraulic proportional valve; 6) the input voltage value is used by the electro-hydraulic proportional valve to control the oil inlet pressure of the hydraulic cylinder; 7) the hydraulic cylinder drives the hydraulic pull rod to generate a reaction torque on the ram; 8) the deflection compensation is completed.

3. The ram deflection compensation method as claimed in claim 2, characterized in that The movement of the ram is carried out in the spindle box, and the movement mode of the ram is linear sliding.

4. The ram deflection compensation method of claim 2 wherein, The spindle box is centrally arranged, and double screw rod transmission is adopted.

Images