CN104785568B - Extruder extrusion process hydraulic system modeling and energy consumption analysis method - Google Patents

Abstract

The invention discloses a hydraulic system modeling and energy consumption analysis method in the extrusion process of an extrusion machine. Taking a 10MN aluminum extrusion machine as the research object, and aiming at the problem of serious energy loss in the extrusion process, the extrusion machine is analyzed by technical means The energy flow direction, energy conversion form and energy consumption of the hydraulic system, and the corresponding theoretical energy consumption formula are given, which will help to summarize the key components of energy consumption and make the energy-saving optimization of the extruder more purposeful.

Description

Modeling and energy consumption analysis method of hydraulic system in extrusion process of extrusion machine

technical field

The invention belongs to the technical field of energy consumption analysis and cost control of an extruder, and in particular relates to a hydraulic system modeling and energy consumption analysis method in the extrusion process of an extruder.

Background technique

In recent years, with the development of aluminum profile industry technology and the need for energy saving and emission reduction, the requirements for the control of energy consumption and product cost of extrusion machines are getting higher and higher.

As the key equipment in the extrusion process production line, the extruder has serious energy loss and low extrusion efficiency. The working efficiency of one extrusion cycle is about 60%, and the energy lost is converted into heat energy. Among them, the recognized energy consumption of the extrusion machine is mainly in the hydraulic extrusion stage, which lasts for a long time and consumes a lot of power, and is the process of extruding aluminum ingots into aluminum products. The power system of the extruder is hydraulic transmission, and energy loss is the main power loss of the hydraulic system.

At present, research on energy saving of extruders includes energy-saving transformation of extruder equipment, parameter optimization of extrusion process, and improvement of yield of extruded products. However, in order to solve the problem, the first thing is to find the problem. The technical method quickly and accurately finds the points to be optimized of the extruder.

Contents of the invention

The present invention takes a 10MN aluminum extrusion machine as the research object, aims at the problem of serious energy loss in the extrusion process, analyzes the energy flow direction, energy conversion form and energy consumption of the hydraulic system of the extrusion machine through technical means, and gives the corresponding The theoretical energy consumption formula helps to summarize the key components of energy consumption, making the energy-saving optimization of the extruder more purposeful.

The invention proposes a hydraulic system modeling and energy consumption analysis method in the extrusion process of an extrusion machine.

Specifically, in order to solve the above technical problems, the technical solution of the present invention is as follows:

The hydraulic system modeling and energy consumption analysis method in the extrusion process of an extrusion machine includes the following steps.

The first step is to carry out the energy consumption analysis of the extrusion process, the energy consumption analysis of the plunger variable pump, the energy consumption analysis of the cartridge valve block and the energy consumption analysis of the extrusion cylinder.

Energy consumption analysis of the extrusion process: observe the components related to energy conversion and energy loss, including plunger variable pumps, cartridge valves, and master cylinders, and establish the power balance equation of the system according to the relationship between input and output energy consumption of components: P _p ＝η _p P _pi ＝P _c +P _v ; Among them, P _pi , P _p , η _p represent the input power, output power and efficiency of the hydraulic pump respectively, P _c is the output power of the main cylinder 1, and P _v is the plug-in Power loss in the valve block.

Energy consumption analysis of variable displacement plunger pump: the different leakage forms are set as follows: pump plunger pair leakage loss q _pp , slipper pair leakage loss q _ps , distribution pair leakage loss q _pv , volume compression loss q _pc ; in addition, the mechanical Efficiency is divided into three parts of loss: Coulomb friction torque loss T _ps caused by relative motion between pump internal parts, torque loss T _pr caused by bearing rolling friction; torque loss T _pv caused by viscous damping of oil in the pump.

The energy consumption relationship of the plunger variable displacement pump is set as follows: q _pa =q _pt -Δq _p =q _pt -(q _pp +q _ps +q _pv +q _pc ), T _pi =T _pa +ΔT _p =T _pa + T _ps +T _pr +T _pv .

The power loss formula of the plunger variable displacement pump: ΔP _p ＝P _pi -P _p ＝2πnT _pi -p _pa q _pa ; where q _pa and q _pt are the actual flow rate and theoretical flow rate of the hydraulic pressure respectively, and T _pi and T _pa are respectively Hydraulic motor supply torque and input torque; p _pa represents the outlet pressure of the plunger variable pump;

Power loss of the cartridge valve block: The power loss of the cartridge valve is expressed as a local pressure loss. When the oil enters the valve port, the flow area at the valve core decreases rapidly, forming a pressure difference and consuming energy. It is related to the opening degree of the valve and the inlet pressure. The power loss caused by the pressure difference can be expressed by the following formula: P _v = Δp _A q _vA ; where Δp _A is the pressure difference of the valve port, and q _vA is the flow rate flowing through the main valve port .

Analysis of the energy consumption of the extrusion cylinder: the power loss ΔP _c of the extrusion cylinder includes the mechanical friction loss P _cf between the piston rod and the piston cylinder, the volume loss P _ck caused by the leakage in the cylinder, and the kinetic energy potential energy loss P caused by the movement of the piston rod _cr , the output power of the extrusion cylinder is P _co , and the power balance equation of the extrusion cylinder is obtained: P _c =P _co +ΔP _c =P _co +P _cf +P _ck +P _cr .

The second step: establish the simulation system model.

Modeling and simulation of the hydraulic system in the extrusion process: set up the hydraulic control system model of the extrusion process.

Piston variable pump model establishment: the pump body is a swash plate axial piston variable pump, including four parts: the distribution plate, the plunger chamber, the swash plate plunger connector and the swash plate controller; among them, four parts are set for the flow distribution plate Two ports respectively represent oil inlet, oil outlet, plunger oil port and cylinder body rotation angle. The oil inlet and oil outlet are respectively connected with the high-pressure chamber and low-pressure chamber of the distribution plate. When the cylinder body rotates once, the plunger completes One-time oil suction and oil discharge; the plunger chamber is composed of plunger, hydraulic chamber and leakage port, one end is connected to the plunger oil port, and the other end is connected to the swash plate plunger connector; the drive shaft inertia input of the swash plate plunger connector When the cylinder rotates, the connector can drive the plunger to reciprocate, and realize oil suction and oil discharge functions according to the output rotation angle; the swash plate controller is connected to the swash plate inertia input end of the swash plate plunger connector, which can be used to adjust The inclination of the swash plate controls the displacement of the pump.

Considering the volume loss of the pump body, including the leakage of the plunger pair and the slipper pair, and the compressibility of the oil, the volume compression loss can be obtained. The sum of the leakage of the distribution pairs of each plunger is expressed at the outlet of the pump body. The mechanical loss is represented by the rotating load torque model with damping, and the parameters of the variable variable pump are expressed as follows: the radial position of the plunger is 0.04m, the diameter of the plunger is 28mm, the number of plungers is 9, the diameter gap of the plunger is 0.01mm, the plunger, cylinder Body contact length 68.4mm, system pressure 400null, maximum swash plate inclination angle 20degree, pressure control valve diameter 6mm, sliding shoe auxiliary flow leakage 5.6e-2*dpL/min, distribution auxiliary flow leakage 1e-2*dpL/min, Coulomb friction The moment loss is 7mm, the rolling friction moment loss is 3mm, the cylinder moment of inertia is 0.02Kgm ² , and the rotation speed is 2100rev/min.

Extrusion cylinder model establishment: Establish the extrusion cylinder model, considering the mechanical friction between the piston rod and the piston cylinder, the internal leakage of the auxiliary oil cylinder, the kinetic energy potential energy of the piston rod movement and the load, and set the parameters of each component as follows: main Cylinder: piston diameter 730mm, piston rod diameter 730mm, zero position 150mm, dead zone volume 50000cm ³ ; auxiliary cylinder: piston diameter 200mm, piston rod diameter 150mm, zero position 30mm, dead zone volume 1000cm ³ , leakage module gap diameter 0.1mm, The gap length of the leakage module is 100mm; the extruded rod: the total mass is 5x10 ⁶ kg; the load in it is obtained from the data collected on site.

Cartridge valve model establishment: the cartridge valve includes a valve body and a valve seat, considering the local pressure loss of the valve, the parameter information of each component is as follows: the valve diameter is 40mm, the area ratio is 14.3:1l, the valve port diameter is 38.5mm, and the valve core The mass is 0.4kg, the valve core is -10~10m, the spring stiffness is 1N/mm, and the pretightening force is 1N.

The third step: verify the simulation results.

Simulation result verification: set the simulation time to 69s, the communication interval to 0.01s, run the model and view the simulation results, get the extrusion speed curve of the extrusion process, and obtain the power characteristics of each energy-consuming element in the extrusion process through post-processing The curve, considering the error between the simulation results and the actual results, further analyzes the energy consumption of the model.

Step 4: Conduct energy consumption analysis.

Energy consumption analysis: conduct energy consumption analysis on the energy consumption components of the model, analyze its power consumption and power loss, including the output energy consumption and loss energy consumption of the plunger variable pump, the partial pressure loss energy consumption of the oil inlet valve, and the pressure relief valve The overflow loss energy consumption, the output energy consumption and the loss energy consumption of the extrusion cylinder, and establish and compare the above energy consumption curves to quantify the energy consumption distribution.

Step 5: Improve energy consumption based on energy consumption analysis.

According to the obtained quantitative distribution data, targeted improvements are made to improve energy efficiency.

The benefits of the present invention are:

The invention analyzes the working principle of the extrusion process and the energy consumption of the hydraulic system, establishes a system simulation model, verifies the correctness of the model, obtains the energy consumption curve of the energy consumption components in the extrusion process, quantifies the energy consumption distribution, and contributes to It is concluded that the main energy consumption loss that causes the extrusion efficiency is not high, and targeted improvements are made. This method and simulation results have excellent theoretical basis and theoretical guiding significance for the research and optimization of extrusion machine energy saving.

Description of drawings

Figure 1 is a schematic diagram of the hydraulic system in the extrusion process of an aluminum extrusion machine; wherein, the reference signs are as follows: 1-main cylinder, 2-auxiliary oil cylinder, 3-extrusion rod, 4-filling valve, 5-main cylinder inlet Valve, 6-Pressure relief valve, 7-Master cylinder return valve, 8-Master cylinder inlet and outlet valve, 9-Sequence valve, 10-Master cylinder return oil valve, 11-Three-phase asynchronous motor, 12-Plunger variable pump , 13-safety valve;

Fig. 2 is the energy flow diagram of the hydraulic process of the aluminum extrusion press;

Fig. 3 is the simulation model of the hydraulic system in the extrusion process;

Figure 4 is a single plunger flow model; among them, 20-distribution pair leakage, 21-distribution plate, 22-oil inlet, 23-oil outlet, 24-plunger oil port, 25-plunger cavity, 26- Swashplate plunger connector, 27-swashplate controller, 28-auxiliary leakage port, 29-plunger, 30-hydraulic chamber;

Fig. 5 is a comparison diagram of extrusion speed between simulation and reality;

Fig. 6 is a comparison diagram of the input energy consumption of the motor between simulation and reality;

Fig. 7 is the output energy consumption diagram in the energy consumption analysis;

Fig. 8 is a graph of energy consumption loss in energy consumption analysis.

detailed description

The drawings are for illustrative purposes only and should not be construed as limiting the invention.

For those skilled in the art, it is understandable that some well-known structures and descriptions thereof may be omitted in the drawings.

The technical solutions in the invention will be clearly and completely described below in conjunction with the description and drawings of the invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The schematic diagram of the hydraulic system in the extrusion process is shown in Figure 1. The extrusion cylinder is composed of two auxiliary cylinders 2 and a main cylinder 1. It is an asymmetrical piston structure. The ends of each piston rod are fixed and connected to the extrusion rod 3. The main function of the auxiliary cylinder 2 is to complete the forward and backward actions of the main cylinder 1, while the main cylinder 1 is responsible for the main extrusion forward action, pushing the extrusion rod 3 into the extrusion cylinder for extrusion work. Through the two-way cartridge valve, the oil circuit of the main cylinder 1 and the auxiliary cylinder 2 can be controlled to realize various working conditions.

The extrusion process refers to the forward stage of extrusion. It is necessary to open the main cylinder inlet valve 5, the sequence valve 9 and the main cylinder oil inlet and return valve 8. Before extrusion, the main cylinder 1 is filled with liquid through the filling valve 4. The pressure relief valve 6 can limit the maximum extrusion force in the extrusion process to realize overload protection. The power part is driven by the three-phase asynchronous motor 11 to drive the plunger variable pump 12 to output high-pressure hydraulic power, and the electric proportional control method can control the swash plate inclination of the plunger variable pump 12, adjust its displacement, and realize the speed control of the extrusion process.

The energy flow of the hydraulic process is shown in Figure 2. The hydraulic system of the extrusion machine includes power components, executive components, control and adjustment components, auxiliary components, transmission media, etc., and the realization of the function of each link is accompanied by energy consumption.

During the extrusion process, the hydraulic system has three energy conversions: 1. First, the motor is energized to convert electrical energy into mechanical energy; 2. Then through the coupling device, the hydraulic pump is driven to convert mechanical energy into hydraulic energy and output high-pressure oil; 3. Finally The extrusion cylinder converts hydraulic energy into mechanical energy for extrusion work.

The conversion between different forms of energy is bound to be accompanied by energy loss, mainly including mechanical friction loss, volume loss, overflow loss, local pressure loss, kinetic energy potential energy loss, etc., and this part of the loss is converted into heat energy to increase the temperature of the oil. high.

Energy consumption analysis of the extrusion process: in the hydraulic transmission system of the extrusion process, focus on observing the components related to energy conversion and energy loss, including the plunger variable pump 12, cartridge valve, master cylinder 1, etc., and according to the input of the components, Output energy consumption relationship, the power balance equation of the system can be established:

P _p =η _p P _pi =P _c +P _v ; where, P _pi , P _p , and η _p represent the input power, output power and efficiency of the hydraulic pump respectively, P _c is the output power of the main cylinder 1, and P _v is Power loss in the cartridge valve block.

Energy consumption analysis of the variable plunger pump 12: The total efficiency of the variable plunger pump 12 mainly includes volumetric efficiency and mechanical efficiency. The volumetric efficiency is due to the leakage of oil from the high pressure chamber of the hydraulic pump into the low pressure chamber during the working process. The main leakage forms are the leakage loss of the pump plunger pair q _pp , the leakage loss of the sliding shoe pair q _ps , the leakage loss of the distribution pair q _pv , the volume Compression loss q _pc . The mechanical efficiency is mainly manifested in the loss of three parts: one is the Coulomb friction torque loss T _ps caused by the relative movement between the pump internal parts, including the sliding friction torque of the distribution pair, the sliding friction torque of the sliding shoe pair, and the sliding friction torque of the ball joint pair. The second is the torque loss T _pr caused by the bearing rolling friction; the third is the torque loss T _pv caused by the viscous damping of the oil in the pump.

The energy consumption relationship of the plunger variable displacement pump is as follows: q _pa = q _pt -Δq _p = q _pt -(q _pp +q _ps +q _pv +q _pc ), T _pi =T _pa +ΔT _p =T _pa +T _ps +T _pr +T _pv (3).

The power loss ΔP _p formula of the plunger variable displacement pump: ΔP _p ＝P _pi -P _p ＝2πnT _pi -pq _pa ; among them, q _pa and q _pt are the actual hydraulic flow and theoretical flow respectively, and T _pi and T _pa are respectively The hydraulic electric motor supplies torque and inputs torque.

The power loss of the cartridge valve block: the cartridge valve controls the oil flow direction of the main oil circuit by adjusting the relative movement between the spool and the valve sleeve and changing the flow cross-sectional area of the valve port. The power loss is mainly manifested as local pressure Loss, when the oil enters the valve port, the flow area at the valve core decreases rapidly, forming a pressure difference and consuming energy. The pressure difference is related to the opening degree of the valve and the inlet pressure. The power loss P _v caused by the pressure difference can be expressed by the following formula: P _v = Δp _A q _vA ; where Δp _A is the pressure difference at the valve port, and q _vA is the flow through the main flow through the valve.

Energy consumption analysis of the extrusion cylinder: the extrusion cylinder can realize the reciprocating motion of the mechanism forward, extrusion and backward during the extrusion process. Its input parameters are the flow and pressure of the oil, and the output parameters are the movement speed and force of the mechanism, etc. ^[ . During extrusion work, high-pressure oil enters the rodless chamber of the extrusion cylinder to push the piston to overcome the metal deformation stress and do work. The power loss ΔP _c mainly includes the mechanical friction loss P _cf between the piston rod and the piston cylinder, and the leakage caused by the cylinder. The volume loss P _ck and the kinetic energy potential energy loss P _cr caused by the movement of the piston rod, the output power of the extrusion cylinder is P _co .

The power balance equation of the extrusion cylinder: P _c =P _co +ΔP _c =P _co +P _cf +P _ck +P _cr .

Modeling and simulation of the hydraulic system in the extrusion process: Enter the AMESim software environment, call the hydraulic library, mechanical library, hydraulic component design library and signal library provided by the system in the sketch mode, and build a simulation model for the above-mentioned plunger variable pump, Carry out HCD (Host Control Driver (HCD (Host Control Driver))) design for the energy consumption and power loss of extrusion cylinder, cartridge valve block and oil circuit, and select the simplest sub-model. The hydraulic control system model of the extrusion process is shown in Figure 3.

Piston variable pump model: the pump body is a swash plate axial piston variable pump, mainly including a flow distribution plate 21, a plunger chamber 25, a swash plate plunger connector 26 and a swash plate controller 27, a single plunger flow model As shown in Figure 4. Among them, the four ports of the distribution plate 21 respectively represent the oil inlet 22, the oil outlet 23, the plunger oil port 24 and the cylinder body angle, and the oil inlet 22 and the oil outlet 23 are respectively connected with the high-pressure chamber and the low-pressure chamber of the distribution plate 21. The cavity is connected, the cylinder rotates once, and the plunger completes oil suction and oil discharge once. The plunger chamber 25 is composed of a plunger 29 , a hydraulic chamber 30 and a secondary leakage port 28 . One end of the plunger chamber 25 is connected to the plunger oil port 24 , and the other end is connected to the swashplate plunger connector 26 . The inertial input end of the transmission shaft of the swash plate plunger connector 26 is connected to the motor. When the cylinder rotates, the swash plate plunger connector 26 can drive the plunger to reciprocate, and realize oil suction and oil discharge functions according to the output rotation angle. The swash plate controller 27 is connected to the swash plate inertia input end of the swash plate plunger connector 26, and can be used to adjust the inclination angle of the swash plate and control the displacement of the pump.

Considering the volume loss of the pump body, including the leakage of the plunger pair and the slipper pair, and the compressibility of the oil, the volume compression loss can be obtained. The sum of the leakage of the distribution pairs of each plunger is expressed at the outlet of the pump body. The mechanical loss is represented by the rotating load torque model with damping, and the parameters of the variable variable pump are expressed as follows: the radial position of the plunger is 0.04m, the diameter of the plunger is 28mm, the number of plungers is 9, the diameter gap of the plunger is 0.01mm, the plunger, cylinder Body contact length 68.4mm, system pressure 400Mpa, maximum swash plate inclination angle 20degree, pressure control valve diameter 6mm, sliding shoe auxiliary flow leakage 5.6e-2*dpL/min, distribution auxiliary flow leakage 1e-2*dpL/min, Coulomb friction The moment loss is 7mm, the rolling friction moment loss is 3mm, the cylinder moment of inertia is 0.02Kgm ² , and the rotation speed is 2100rev/min.

Extrusion cylinder model: use the HCD library and signal library of AMESim to establish the extrusion cylinder model ^[4] according to the structure principle and power loss of the extrusion cylinder, and consider the mechanical friction between the piston rod and the piston cylinder and the internal pressure of the auxiliary cylinder respectively. Leakage, kinetic energy and potential energy of piston rod movement and load, set the parameters of each component as follows: main cylinder: piston diameter 730mm, piston rod diameter 730mm, zero position 150mm, dead zone volume 50000cm ³ ; auxiliary cylinder: piston diameter 200mm, piston The rod diameter is 150mm, the zero point position is 30mm, the dead zone volume is 1000cm ³ , the leakage module gap diameter is 0.1mm, and the leakage module gap length is 100mm; extruded rod: total mass 5x10 ⁶ kg; the load in it is obtained through data collected on the industrial site.

Cartridge valve model: The cartridge valve includes a valve body and a valve seat. It is designed through the HCD library ^[6] , considering the local pressure loss of the valve. The parameter information of each component is as follows: the valve diameter is 40mm, the area ratio is 14.3:1null, The diameter of the valve port is 38.5mm, the mass of the valve core is 0.4kg, the valve core is -10~10m, the spring stiffness is 1N/mm, and the pre-tightening force is 1N.

Simulation result verification: set the simulation time to 69s, the communication interval to 0.01s, run and view the simulation results, get the extrusion speed curve of the extrusion process, and obtain the power characteristic curve of each energy-consuming element in the extrusion process through post-processing , in order to verify the effectiveness of the model, the simulation results are compared with the experimental data, as shown in Figures 5 and 6, the simulation and actual extrusion completion times are 63s and 66s, respectively, and the extrusion completion time is basically the same; due to the simulation consideration Ideally, although there are errors in the simulated speed and motor input power, the overall trend of the curves is not much different, and the energy consumption of the model can be further analyzed.

Energy consumption analysis: conduct energy consumption analysis on the energy consumption components of the model, analyze its power consumption and power loss, including the output energy consumption and loss energy consumption of the plunger variable pump, the partial pressure loss energy consumption of the oil inlet valve, and the pressure relief valve The overflow loss energy consumption, the output energy consumption and the loss energy consumption of the extrusion cylinder are shown in Figures 7 and 8.

According to the above simulation results, it can clearly reflect the energy consumption and loss of each energy-consuming component in the extrusion process. Through further calculation, it can be known that the total energy consumption is 1.17kW, and the useful work output by the extrusion cylinder accounts for the total energy consumption. 71.2% of the energy loss, the largest energy loss is the overflow loss accounted for 17.1%, the energy loss of the variable pump accounted for 9.15%, the energy loss of the extrusion cylinder accounted for 2.1%, and other losses accounted for 0.45%.

Improve energy consumption: According to the obtained quantitative distribution data, make targeted improvements to improve energy efficiency.

The working principle of the extrusion process and the energy consumption of the hydraulic system were analyzed, and the system simulation model was established on the AMESim platform to verify the correctness of the model. And get the energy consumption curve of the energy-consuming components in the extrusion process, quantify the energy consumption distribution, and conclude that the energy loss of extrusion overflow is the main reason for the low extrusion efficiency, and the overflow flow of the pressure relief valve can be reduced or the accumulator can be used Recovery of lost energy; secondly, the efficiency of the variable pump is not high, and other variable flow transmission methods can be used to reduce system energy consumption. This research method and simulation results have a certain theoretical basis for the research on energy saving of extruders.

To sum up, it is the content of the embodiments of the present invention, and it is obvious that the embodiments of the present invention are not limited thereto, and the functions of the present invention can be used to realize corresponding requirements according to different application environments.

Claims (5)

1. The hydraulic system modeling and energy consumption analysis method of the extrusion process of the extrusion machine, including the following steps: Step 1: Carry out energy consumption analysis of extrusion process, piston variable pump energy consumption analysis, cartridge valve valve block energy consumption analysis and extrusion cylinder energy consumption analysis; Energy consumption analysis of the extrusion process: observe the components related to energy conversion and energy loss, including plunger variable pumps, cartridge valves, and master cylinders, and establish the power balance equation of the system according to the relationship between input and output energy consumption of components: P _p =η _p P _pi =P _c +P _v ; Wherein, P _pi , P _p , η _p respectively represent the input power, output power and efficiency of the hydraulic pump, P _c is the output power of the main cylinder (1), and P _v is Power loss in the cartridge valve block; Energy consumption analysis of variable displacement plunger pump: the different leakage forms are set as follows: pump plunger pair leakage loss q _pp , slipper pair leakage loss q _ps , distribution pair leakage loss q _pv , volume compression loss q _pc ; in addition, the mechanical Efficiency is divided into three parts: the coulomb friction torque loss T _ps caused by the relative movement between the pump internal parts, the torque loss T _pr caused by the bearing rolling friction; the torque loss T _pv caused by the viscous damping of the oil in the pump; The energy consumption relationship of the plunger variable displacement pump is set as follows: q _pa =q _pt -Δq _p =q _pt -(q _pp +q _ps +q _pv +q _pc ), T _pi =T _pa +ΔT _p =T _pa + T _ps +T _pr +T _pv ; The power loss formula of the plunger variable displacement pump: ΔP _p ＝P _pi -P _p ＝2πnT _pi -p _pa q _pa ; where q _pa and q _pt are the actual flow rate and theoretical flow rate of the hydraulic pressure respectively, and T _pi and T _pa are respectively Hydraulic motor supply torque and input torque; p _pa represents the outlet pressure of the plunger variable pump; Power loss of the cartridge valve block: The power loss of the cartridge valve is expressed as a local pressure loss. When the oil enters the valve port, the flow area at the valve core decreases rapidly, forming a pressure difference and consuming energy. It is related to the opening degree of the valve and the inlet pressure. The power loss caused by the pressure difference can be expressed by the following formula: P _v = Δp _A q _vA ; where Δp _A is the pressure difference of the valve port, and q _vA is the flow rate flowing through the main valve port ; Analysis of the energy consumption of the extrusion cylinder: the power loss ΔP _c of the extrusion cylinder includes the mechanical friction loss P _cf between the piston rod and the piston cylinder, the volume loss P _ck caused by the leakage in the cylinder, and the kinetic energy potential energy loss P caused by the movement of the piston rod _cr , the output power of the extrusion cylinder is P _co , and the power balance equation of the extrusion cylinder is obtained: P _c =P _co +ΔP _c =P _co +P _cf +P _ck +P _cr ; The second step: establish the simulation system model; Modeling and simulation of the hydraulic system in the extrusion process: set up the hydraulic control system model of the extrusion process; Piston variable pump model establishment; Extrusion cylinder model establishment; Cartridge valve model establishment; The third step: verify the simulation results; Simulation result verification: set the simulation time to 69s, and the communication interval to 0.01s, run the model and view the simulation results to obtain the extrusion speed curve of the extrusion process, and obtain the power characteristic curve of each energy-consuming element in the extrusion process through processing , and then further analyze the energy consumption of the model; Step 4: Carry out energy consumption analysis; Energy consumption analysis: conduct energy consumption analysis on the energy consumption components of the model, analyze its power consumption and power loss, including the output energy consumption and loss energy consumption of the plunger variable pump, the partial pressure loss energy consumption of the oil inlet valve, and the pressure relief valve The overflow loss energy consumption, the output energy consumption and the loss energy consumption of the extrusion cylinder, and establish and compare the above energy consumption curves to quantify the energy consumption distribution; Step 5: Improve energy consumption based on energy consumption analysis; Improve energy consumption: According to the obtained quantitative energy consumption distribution data, make targeted improvements to improve energy consumption efficiency. 2. The hydraulic system modeling and energy consumption analysis method in the extrusion process of an extrusion press according to claim 1, characterized in that in the second step, the plunger variable pump model is established: the pump body is a swash plate type The axial piston variable displacement pump includes four parts: the distribution plate, the plunger cavity, the swash plate plunger connector and the swash plate controller; among them, four ports are set for the flow control plate, respectively representing the oil inlet, the oil outlet, The oil port of the plunger and the corner of the cylinder body, its oil inlet and oil outlet are respectively connected with the high-pressure chamber and the low-pressure chamber of the distribution plate, the cylinder body rotates once, and the plunger completes oil suction and oil discharge once; the plunger chamber is formed by the plunger , a hydraulic cavity and a leak port, one end is connected to the plunger oil port, and the other end is connected to the swash plate plunger connector; the drive shaft inertia input end of the swash plate plunger connector is connected to the motor, when the cylinder rotates, the swash plate plunger The connector can drive the plunger to reciprocate, and realize the oil suction and oil discharge functions according to the output rotation angle; the swash plate controller is connected to the swash plate inertia input end of the swash plate plunger connector, which can be used to adjust the swash plate inclination angle and control the displacement of the pump . 3. The hydraulic system modeling and energy consumption analysis method for the extrusion process of an extrusion machine according to claim 2, characterized in that the parameters of the variable pump are as follows: the radial position of the plunger is 0.04m, the diameter of the plunger is 28mm, The number of plungers is 9, the gap between the diameter of the plunger is 0.01mm, the contact length between the plunger and the cylinder is 68.4mm, the system pressure is _400Mpa , the maximum swash plate inclination angle is 20degree, the diameter of the pressure control valve is 6mm, and the leakage of the auxiliary flow of the sliding shoe is 5.6e-2* dpL/min, flow leakage of distribution valve 1e-2*dpL/min, coulomb friction loss 7mm, rolling friction loss 3mm, cylinder moment of inertia 0.02Kgm ² , speed 2100rev/min; where, e is the base of natural logarithm e, dp is differential. 4. The hydraulic system modeling and energy consumption analysis method of the extrusion process of the extrusion machine according to claim 1, characterized in that in the second step, the extrusion cylinder model is set up: the parameters of each element are set as follows Shown: master cylinder: piston diameter 730mm, piston rod diameter 730mm, zero position 150mm, dead zone volume 50000cm ³ ; auxiliary cylinder: piston diameter 200mm, piston rod diameter 150mm, zero position 30mm, dead zone volume 1000cm ³ , leakage module gap diameter 0.1mm, the gap length of the leakage module is 100mm; the extruded rod: the total mass is 5x10 ⁶ kg; the load is obtained from the data collected on site. 5. The hydraulic system modeling and energy consumption analysis method for the extrusion process of the extrusion machine according to claim 1, characterized in that in the second step, the cartridge valve model is established: the parameter information of each component is as follows : The valve diameter is 40mm, the area ratio is 14.3:1, the valve port diameter is 38.5mm, the valve core quality is 0.4kg, the valve core is -10～10m, the spring stiffness is 1N/mm, and the preload force is 1N.