A kinetic energy recovery system and method for die casting machine mold opening and closing

Abstract

This invention relates to the field of hydraulic transmission technology, and more particularly to a kinetic energy recovery system and method for die-casting machine mold opening and closing. The system includes a mold opening and closing hydraulic cylinder, a main oil pump, a reversing valve assembly, a hybrid energy recovery unit, and a measurement and control unit. The hybrid energy recovery unit includes a peak-sinking hydraulic energy storage path and a speed-controlling electric energy storage path. The control unit switches between the peak-sinking hydraulic energy storage path and the speed-controlling electric energy storage path based on the operating data of the mold opening and closing hydraulic cylinder and the hybrid energy recovery unit. A recovery method based on the above system is also disclosed. Using the aforementioned die-casting machine mold opening and closing kinetic energy recovery system and method, energy is recovered through the coupled and coordinated operation of the peak-sinking hydraulic energy storage path and the speed-controlling electric energy storage path. The accumulator performs peak-sinking first, followed by the supercapacitor sequentially, achieving a rapid increase in the movement speed of the mold opening and closing hydraulic cylinder, reducing the rated power of the main pump, and realizing flexible stopping with high-precision speed control, reducing the impact on the equipment when stopping at the end of the stroke.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydraulic transmission, and in particular to a die casting machine mold opening and closing kinetic energy recovery system and a recovery method. BACKGROUND

[0002] The die casting machine is mainly driven by a constant-speed motor and a quantitative pump, and some new models use a servo motor + variable pump (or built-in servo pump) to reduce standby loss. The energy flow of the die casting machine mold opening and closing system presents the characteristics of "large instantaneous flow, frequent acceleration and deceleration, high peak power, and low average power". At the same time, there is a lot of throttling dissipation in the terminal deceleration and low speed section, which leads to oil temperature rise, cooling load increase, valve impact and noise problem. In the prior art, energy accumulators are used for energy recovery, and gas bag type accumulators are arranged in the mold opening and closing or injection circuit, for example, the application publication No. CN113357234A discloses a digital control based accumulator group engineering machinery rotary device energy recovery system, which realizes the adaptation of the system to different working states by arranging multiple accumulators, so that the system achieves a better energy recovery efficiency and utilization efficiency under different loads. Although the application of the accumulator realizes energy recovery, the single recovery path cannot realize precise speed control, and it is difficult to realize the consistency of the programmable speed curve and position of the terminal deceleration only by the accumulator, and the accumulator is limited by the pressure window and the gas variable characteristics. SUMMARY

[0003] The purpose of the present application is to provide a die casting machine mold opening and closing kinetic energy recovery system and a recovery method to solve the above technical problems.

[0004] To achieve the above purpose, the present application provides a die casting machine mold opening and closing kinetic energy recovery system, which comprises a mold opening and closing hydraulic cylinder, a main oil pump, a first reversing valve and a second reversing valve. The mold opening and closing hydraulic cylinder has a rodless cavity and a rod cavity. The first reversing valve is arranged on a first passage between the main oil pump and the rodless cavity. The second reversing valve is arranged on a second passage between the first reversing valve and the rod cavity. The system further comprises a mixed energy recovery unit and a control unit. The mixed energy recovery unit comprises a peak-holding hydraulic energy storage passage and a speed control electric side energy storage passage. The connection point of the peak-holding hydraulic energy storage passage and the speed control electric side energy storage passage is connected with a deceleration passage. The first reversing valve and the second reversing valve are both arranged on the deceleration passage. The connection point of the peak-holding hydraulic energy storage passage and the speed control electric side energy storage passage is connected with one end of an acceleration passage. The other end of the acceleration passage is connected with the first passage between the first reversing valve and the main oil pump. The acceleration passage is provided with a third reversing valve in parallel, which is used to control the opening and closing of a cartridge valve on the acceleration passage.

[0005] The control unit is used to collect the operation data of the mold opening and closing hydraulic cylinder and the mixed energy recovery unit, and to switch the peak-holding hydraulic energy storage passage and the speed control electric side energy storage passage according to the operation data.

[0006] Preferably, at least one accumulator and a first control valve are arranged on the hydraulic energy storage passage of the duffel peak, and the first control valve is used to control the oil return direct charging and energy release of the accumulator. A safety passage is connected between the accumulator and the first control valve, and a safety valve is arranged at the tail end of the safety passage to limit the maximum pressure of the accumulator.

[0007] Preferably, a hydraulic motor / pump integrated machine and a second control valve are arranged on the speed control electric side energy storage passage, the hydraulic motor / pump integrated machine is connected with a bidirectional three-phase active rectifier module, the bidirectional three-phase active rectifier module is connected with a filter, the filter is connected with a first DC-DC conversion module, the first DC-DC conversion module and the filter are connected with a high-voltage contactor, the high-voltage contactor is connected with a super capacitor group and is provided with a brake resistance module, and the super capacitor group is connected with the bidirectional three-phase active rectifier module through a second DC-DC conversion module.

[0008] Preferably, the super capacitor group is provided with a super capacitor management module, the super capacitor management module is used for voltage balancing, temperature monitoring and health state monitoring and evaluation of the super capacitor group, the super capacitor group is connected with a DC bus, and the DC bus is connected with an energy interface of a power consumption device to realize energy sharing.

[0009] Preferably, the deceleration channel and the acceleration passage are both provided with a check valve or a shuttle valve for preventing the electro-hydraulic passage from being backfilled.

[0010] Preferably, the first passage, the deceleration channel and the acceleration passage are all connected with an overflow valve.

[0011] Preferably, the measurement and control unit comprises a pressure acquisition module, an electric parameter acquisition module, an opening and closing mold parameter acquisition module, a temperature acquisition module and a control module; the pressure acquisition module, the electric parameter acquisition module, the opening and closing mold parameter acquisition module and the temperature acquisition module are all connected with the control module, and are used to control the state of the corresponding components according to the collected data;

[0012] The pressure acquisition module is used to collect the accumulator pressure.

[0013] The electric parameter acquisition module is used to collect the voltage of the DC bus.

[0014] The opening and closing mold parameter acquisition module is used to collect the displacement and speed of the opening and closing mold.

[0015] The temperature acquisition module is used to collect the oil temperature and the environmental temperature, and is used for temperature compensation of the subsequent accumulator pressure value.

[0016] In the energy recovery stage, the hydraulic energy storage path of the pocket peak is preferentially opened to make the oil return directly to the accumulator; when the movable mold reaches the preset displacement or speed and the precision reduction control is required, the speed control electric side energy storage path is switched on to drive the hydraulic motor / pump integrated machine, and the converted electric energy is stored in the super capacitor group;

[0017] In the energy release stage, the first control valve is preferentially opened to make the accumulator release energy to the mold opening and closing hydraulic cylinder to provide peak flow; when the accumulator pressure drops to the lower threshold, the speed control electric side energy storage path drives the hydraulic motor / pump integrated machine as a pump to supplement power;

[0018] According to the accumulator pressure window and the DC bus voltage window, the threshold trigger soft switching and power distribution are implemented;

[0019] When the DC bus is overvoltage and the first DC-DC conversion module has limited power, the brake resistance module is used to protect the super capacitor group.

[0020] Based on the above-mentioned recovery method of the die casting machine mold opening and closing kinetic energy recovery system, the specific steps are as follows:

[0021] Step S1: According to the speed-time curve of the die casting machine, the mold opening and closing cycle is divided into working conditions;

[0022] Step S2: According to the working condition division, the switching strategy is set;

[0023] Step S3: According to the switching strategy and the collected operation data, the switching of the hydraulic energy storage path of the pocket peak and the speed control electric side energy storage path is carried out to realize energy recovery in different working conditions.

[0024] Preferably, the mold opening and closing cycle is divided into six working conditions, which are high-speed mold closing T1, low-speed mold closing T2, mold closing T3, low-speed mold opening T4, high-speed mold opening T5 and mold opening T6; the mold opening includes the high-speed to low-speed transition section T6-1 and the mold opening terminal deceleration section T6-2.

[0025] Preferably, in the low-speed mold closing T2 and high-speed to low-speed transition section T6-1 stages, the oil return preferentially enters the accumulator in the hydraulic energy storage path of the pocket peak through the deceleration channel to form a back pressure state; when the movable mold reaches the preset speed or displacement and the precision reduction control is required, the speed control electric side energy storage path is switched to convert the energy into electric energy through the hydraulic motor / pump integrated machine and store it in the super capacitor group;

[0026] In the mold closing T3, low-speed mold opening T4 and mold opening terminal deceleration section T6-2 stages, the oil return preferentially enters the switched speed control electric side energy storage path through the deceleration channel, and the electromagnetic torque of the hydraulic motor / pump integrated machine is closed loop tracked according to the deceleration or back pressure to realize the speed control and energy recovery of the movable mold speed curve;

[0027] In the high-speed clamping T1 and high-speed opening T5 stages, the accumulator releases energy to hold the peak, to establish the high-speed running state, when the accumulator pressure drops to the lower limit, switch to the speed control electric side energy storage path, through the super capacitor group to drive the hydraulic motor / pump integrated machine to supplement energy;

[0028] The threshold soft switching and power distribution are implemented based on the accumulator pressure window and the DC bus voltage window; when the bus voltage exceeds the first threshold, the power is limited first, and when it still exceeds the threshold, the brake resistance module is put into operation to absorb the excess energy;

[0029] Before shutdown or maintenance, the first control valve and the second control valve enter the safe working condition, and the super capacitor group temperature is within the set temperature range, so that the residual energy of the accumulator is stored in the super capacitor group after being converted by the hydraulic motor / pump integrated machine, and the high-voltage contactor is disconnected to make the DC bus power off, and when the super capacitor group temperature is not within the set temperature range, the brake resistance module is used to release energy.

[0030] Therefore, the die casting machine opening and closing mold kinetic energy recovery system and the recovery method have the beneficial effects that:

[0031] (1) The mixed energy recovery unit includes a peak holding hydraulic energy storage path and a speed control electric side energy storage path, and the peak holding hydraulic energy storage path and the speed control electric side energy storage path are coupled and cooperated for energy recovery, the accumulator holds the peak first, and the super capacitor sequentially receives, so that the movement speed of the opening and closing mold hydraulic cylinder is quickly improved, the rated power of the main pump is reduced, and flexible parking of high-precision speed control is realized, reducing the impact on the equipment when parking at the end of the stroke.

[0032] (2) The measurement and control unit switches the peak holding hydraulic energy storage path and the speed control electric side energy storage path through the running data of the opening and closing mold hydraulic cylinder and the mixed energy recovery unit, i.e. threshold soft switching and power distribution are performed according to the accumulator pressure window and the DC bus voltage window, forming a cooperative control of electric side programmable speed control + accumulator back pressure covering six working conditions, and the safety and stability of switching are ensured by threshold soft switching and valve hard interlocking, while meeting the V-T curve speed and forming process requirements, the rated power of the main pump, overflow and cooling loss are significantly reduced.

[0033] The technical solutions of the present application will be further described in detail below with the help of the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 It is a schematic diagram of a die casting machine opening and closing mold kinetic energy recovery system of the present application;

[0035] Figure 2 It is a speed-time curve diagram of the opening and closing mold cycle;

[0036] Figure 3Schematic diagram of oil circuit in high-speed clamping T1 stage

[0037] Figure 4 Schematic diagram of oil circuit in low-speed clamping T2 stage

[0038] Figure 5 Schematic diagram of oil circuit in clamping T3 stage

[0039] Figure 6 Schematic diagram of oil circuit in low-speed opening T4 stage

[0040] Figure 7 Schematic diagram of oil circuit in high-speed opening T5 stage

[0041] Figure 8 Schematic diagram of oil circuit in opening T6 stage

[0042] Figure 9 Schematic diagram of oil circuit in shutdown or maintenance.

[0043] Reference signs

[0044] 1, opening and closing hydraulic cylinder; 11, rodless cavity; 12, rod cavity; 2, main oil pump; 3, first reversing valve; 4, second reversing valve; 5, first passage; 6, second passage; 7, mixed energy recovery unit; 71, peak-holding hydraulic energy storage passage; 711, accumulator; 712, first control valve; 713, safety passage; 714, safety valve; 72, speed control electric side energy storage passage; 721, hydraulic motor / pump integrated machine; 722, second control valve; 723, bidirectional three-phase active rectifier module; 724, filter; 725, first DC-DC conversion module; 726, high-voltage contactor; 727, brake resistance module; 728, second DC-DC conversion module; 729, super capacitor group; 7291, super capacitor management module; 73, speed reduction passage; 74, speed-up passage; 741, third reversing valve; 742, cartridge valve; 75, check valve; 8, overflow valve. DETAILED DESCRIPTION

[0045] In the description of the present application, it should be noted that the terms "upper", "lower", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present application is usually placed, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "provided", "mounted", "connected" should be understood broadly, for example, can be fixedly connected, can also be detachably connected, or integrally connected; can be mechanically connected, can also be electrically connected; can be directly connected, can also be indirectly connected through an intermediate medium, can be internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0046] The embodiments of the present application will be described in detail below with reference to the drawings.

[0047] As Figure 1 shown, a die casting machine opening and closing mold kinetic energy recovery system, including opening and closing mold hydraulic cylinder 1, main oil pump 2, first reversing valve 3 and second reversing valve 4, opening and closing mold hydraulic cylinder 1 has a rodless cavity 11 and a rod cavity 12, the first reversing valve 3 is arranged on the first passage 5 between the main oil pump 2 and the rodless cavity 11, the second reversing valve 4 is arranged on the second passage 6 between the first reversing valve 3 and the rod cavity 12, further comprising a mixed energy recovery unit 7 and a measurement and control unit, the mixed energy recovery unit 7 comprises a peak-holding hydraulic energy storage passage 71 and a speed control electric side energy storage passage 72, the connection point of the peak-holding hydraulic energy storage passage 71 and the speed control electric side energy storage passage 72 is connected with a speed reduction channel 73, and the first reversing valve 3 and the second reversing valve 4 are arranged on the speed reduction channel 73; the connection point of the peak-holding hydraulic energy storage passage 71 and the speed control electric side energy storage passage 72 is connected with one end of a speed-up passage 74, the other end of the speed-up passage 74 is connected on the first passage 5 between the first reversing valve 3 and the main oil pump 2, and the speed-up passage 74 is provided with a third reversing valve 741 in parallel, for controlling the opening and closing of a cartridge valve 742 on the speed-up passage 74. The speed reduction channel 73 and the speed-up passage 74 are both provided with a check valve 75 for preventing the mutual backflow of the electro-hydraulic passage.

[0048] A accumulator 711 and a first control valve 712 are arranged on the peak-holding hydraulic energy storage passage 71, the first control valve 712 is used for controlling the oil return direct filling and energy release of the accumulator 711, a safety passage 713 is connected on the peak-holding hydraulic energy storage passage 71 between the accumulator 711 and the first control valve 712, a safety valve 714 is arranged at the tail end of the safety passage 713, for limiting the maximum pressure of the accumulator 711.

[0049] The hydraulic motor / pump integrated machine 721 is connected with a bidirectional three-phase active rectifier module 723, the bidirectional three-phase active rectifier module 723 is connected with a filter 724, the filter 724 is connected with a first DC-DC conversion module 725, the first DC-DC conversion module 725 and the filter 724 are connected with a high-voltage contactor 726, the high-voltage contactor 726 is connected with a super capacitor group 729 and is provided with a brake resistor module 727, and the super capacitor group 729 is connected with the bidirectional three-phase active rectifier module 723 through a second DC-DC conversion module 728. The super capacitor group 729 is provided with a super capacitor management module 7291, the super capacitor management module 7291 is used for voltage equalization, temperature monitoring and health state monitoring and evaluation of the super capacitor group 729, the super capacitor group 729 is connected with a DC bus, and the DC bus is connected with an energy interface of a power consumption device to realize energy sharing.

[0050] The first passage 5, the deceleration channel 73 and the acceleration channel 74 are all connected with an overflow valve 8.

[0051] The control unit is used for collecting operation data of the mold opening and closing hydraulic cylinder 1 and the hybrid energy recovery unit 7, and switching the peak-holding hydraulic energy storage passage 71 and the speed control electric side energy storage passage 72 according to the operation data.

[0052] The measurement and control unit comprises a pressure acquisition module, an electric parameter acquisition module, a mold opening and closing parameter acquisition module, a temperature acquisition module and a control module; the pressure acquisition module, the electric parameter acquisition module, the mold opening and closing parameter acquisition module and the temperature acquisition module are connected with the control module, and are used for controlling the state of the corresponding components according to the collected data.

[0053] The pressure acquisition module is used for collecting the pressure of the accumulator 711.

[0054] The electric parameter acquisition module is used for collecting the voltage of the DC bus.

[0055] The mold opening and closing parameter acquisition module is used for collecting the displacement and speed of the mold opening and closing.

[0056] The temperature acquisition module is used for collecting the oil temperature and the environmental temperature, and is used for temperature compensation of the subsequent accumulator 711 pressure value.

[0057] In the energy recovery stage, the peak-holding hydraulic energy storage passage 71 is preferentially opened, so that the returned oil is directly charged to the accumulator 711; when the moving die reaches a preset displacement or speed, and the deceleration control with a set precision is required, the speed control electric side energy storage passage 72 is switched on, so that the returned oil drives the hydraulic motor / pump integrated machine 721, and the converted electric energy is stored in the super capacitor group 729.

[0058] The first control valve 712 is opened preferentially in the energy release stage to make the accumulator 711 release energy to the mold opening and closing hydraulic cylinder 1 to provide peak flow; when the accumulator 711 pressure drops to the lower threshold, the speed control electric side energy storage passage 72 is driven by the hydraulic motor / pump integrated machine 721 to supplement power as a pump.

[0059] The soft switching and power distribution are implemented according to the threshold triggering of the accumulator 711 pressure window and the DC bus voltage window.

[0060] When the DC bus is overvoltage and the first DC-DC conversion module 725 has limited power, the brake resistance module 727 is put into operation to protect the super capacitor group 729.

[0061] Based on the above-mentioned die casting machine mold opening and closing kinetic energy recovery system recovery method, the specific steps are as follows:

[0062] Step S1: According to the speed-time curve of the die casting machine, the mold opening and closing period is divided into working conditions. As shown in the figure, the mold opening and closing period is divided into six working conditions, i.e. high-speed mold closing T1, low-speed mold closing T2, mold closing T3, low-speed mold opening T4, high-speed mold opening T5 and mold opening T6; the mold opening includes high-speed to low-speed transition section T6-1 and mold opening terminal deceleration section T6-2. Figure 2

[0063] Step S2: According to the working condition division, the switching strategy is set.

[0064] Step S3: According to the switching strategy and the collected operation data, the switching of the peak-holding hydraulic energy storage passage 71 and the speed control electric side energy storage passage 72 is carried out to realize energy recovery in different working conditions.

[0065] In the low-speed mold closing T2 and high-speed to low-speed transition section T6-1 stages, the oil return preferentially enters the accumulator 711 in the peak-holding hydraulic energy storage passage 71 through the deceleration passage 73 to form a back pressure state; when the moving die reaches the preset speed or displacement and the accuracy of the deceleration control needs to be set, the speed control electric side energy storage passage 72 is switched to convert the energy into electric energy through the hydraulic motor / pump integrated machine 721 and store it in the super capacitor group 729.

[0066] In the mold closing T3, low-speed mold opening T4 and mold opening terminal deceleration section T6-2 stages, the oil return preferentially enters the switched speed control electric side energy storage passage 72 through the deceleration passage 73, and the electromagnetic torque of the hydraulic motor / pump integrated machine 721 is closed loop tracked according to the deceleration or back pressure to realize the speed control and energy recovery of the moving die speed curve.

[0067] ​In the high-speed clamping T1 and high-speed opening T5 stage, the accumulator 711 releases energy to the peak, establishes the high-speed running state, when the accumulator 711 pressure drops to the lower limit value, switch to the speed control electric side energy storage path 72, through the super capacitor group 729 drive hydraulic motor / pump integrated machine 721 to supplement energy.

[0068] Based on the accumulator 711 pressure window and the DC bus voltage window to implement threshold soft switching and power distribution; when the bus voltage exceeds the first threshold, limit the power first, still over threshold, put into brake resistance module 727 to absorb excess energy.

[0069] Before shutdown or maintenance, the first control valve 712 and the second control valve 722 enter the safe working condition, and the temperature of the super capacitor group 729 is in the set temperature range, so that the residual energy of the accumulator 711 is converted by the hydraulic motor / pump integrated machine 721 and stored in the super capacitor group 729, and the high-voltage contactor 726 is disconnected to make the DC bus power off, when the temperature of the super capacitor group 729 is not in the set temperature range, use brake resistance module 727 to release energy.

[0070] The specific actual process is as follows:

[0071] High-speed clamping T1 stage:

[0072] Valve position: first commutation valve left position, second commutation valve 4 left position; third commutation valve 741 right position, cartridge valve 742 open; first control valve 712 left position first, right position second, accumulator 711 releases energy, second control valve 722 right position first, left position second, electric side backup.

[0073] Process: preferentially release energy from the accumulator 711 to quickly increase flow, when the accumulator is close to the lower limit, the first control valve 712 is closed, the second control valve 722 is opened, and the shared super capacitor drives M / G as a pump to continue to supplement flow, maintaining high speed. The specific oil circuit is shown in Figure 3 .

[0074] Low-speed clamping T2 stage (energy recovery):

[0075] Valve position: first reversing valve 3 left position, second reversing valve 4 middle position; third reversing valve 741 left position (plug-in valve 742 closed); first control valve 712 left position (open), second control valve 722 right position (closed). In the working process of low-speed mold closing, the first reversing valve 3 is placed in the left position, the second reversing valve 4 is placed in the middle position, the mold opening and closing hydraulic cylinder 1 is released from the differential connection state, the third reversing valve 741 is in the left position, and the plug-in valve 742 is in the closed state. The first control valve 712 is placed in the left position and is in the open state, and the second control valve 722 is placed in the right position and is in the closed state. The oil return of the rod cavity 12 enters the accumulator 711 through the first control valve 712, the kinetic energy of the movable mold is converted into potential energy in the accumulator 711, and the speed of the movable mold is rapidly reduced. When the accumulator 711 is over-pressurized due to unexpected reasons, the safety valve 714 can be opened to release the excess pressure. The oil circuit is as follows Figure 4 As shown in the figure, this stage is the energy recovery link.

[0076] Process: The oil return of the rod cavity 12 enters the accumulator 711 through the first control valve 712, the kinetic energy is converted into potential energy, and the cylinder speed is rapidly reduced. When approaching the upper limit of the accumulator, the first control valve 712 is closed, the second control valve 722 is opened, and the excess kinetic energy is transferred to the super capacitor system. When the accumulator 711 is over-pressurized due to unexpected reasons, the safety valve 714 can be opened to release the excess pressure.

[0077] Mold closing T3 stage:

[0078] Valve position: first reversing valve 3 left position, second reversing valve 4 middle position; third reversing valve 741 left position (plug-in valve 742 closed); first control valve 712 right position (closed), second control valve 722 left position (open).

[0079] Process: The oil return of the rod cavity 12 drives the hydraulic motor / pump integrated machine 721 (motor state) to convert the kinetic energy of the mold opening and closing hydraulic cylinder 1 into electrical energy, which is converted into electrical energy through a bidirectional three-phase active rectifier module 723, a filter 724 and a first DC-DC conversion module 725, and finally stored in the super capacitor group 729 through a high-voltage contactor 726. The required electrical energy is stored in the super capacitor group 729, and the electrical energy output by the filter 724 is monitored. When the electrical energy output by the filter 724 is direct current 680-760V, the high-voltage contactor 726 is directly connected, and the electrical energy is output to the shared super capacitor group 729. If the electrical energy output by the filter 724 does not meet the requirements, the first DC-DC conversion module 725 is needed to convert the electrical energy into a set range, and then output the electrical energy to the shared super capacitor group 729. In this process, the super capacitor management module 7291 monitors the state of the shared super capacitor group 729. When the recovered energy is excessive or the temperature of the super capacitor group 729 is too high, the brake resistor module 727 is put into operation. Through the configuration of electromagnetic torque, the speed of the mold opening and closing hydraulic cylinder 1 can be accurately controlled until it stops at the end position, and the mold closing process is completed, as followsFigure 5 as shown.

[0080] Low-speed mold opening T4 stage:

[0081] Valve position: first reversing valve 3 right position, second reversing valve 4 middle position; third reversing valve 741 left position (plug-in valve 742 closed); first control valve 712 right position (closed), second control valve 722 left position (open).

[0082] Process: high-pressure oil flows from the rod cavity 12 into the push piston rod to advance, the back pressure of the rodless cavity 11 is precisely controlled by the hydraulic motor / pump integrated machine 721, to realize stable mold vacuum breaking and effective detection of the mold clamping state, and at the same time, the oil return energy is recovered to the super capacitor group 729, as shown below Figure 6 as shown.

[0083] High-speed mold opening T5 stage:

[0084] Valve position: first reversing valve 3 right position, second reversing valve 4 right position; third reversing valve 741 right position (plug-in valve 742 open); first control valve 712 left position first and then right position (open→closed), second control valve 722 right position first and then left position (closed→open).

[0085] Process: first, the potential energy is directly released by the accumulator 711 to provide peak flow and quickly increase the operating speed of the mold opening and closing hydraulic cylinder 1, when the accumulator 711 pressure approaches the lower limit, the first control valve 712 is closed, and the second control valve 722 is opened, the super capacitor drives the hydraulic motor / pump integrated machine 721 to provide additional hydraulic flow to the hydraulic system, to maintain the mold opening and closing hydraulic cylinder 1 in a high-speed mold opening state, as shown below Figure 7 as shown.

[0086] Mold opening T6 stage:

[0087] Valve position: first reversing valve 3 right position, second reversing valve 4 middle position; third reversing valve 741 left position; first control valve 712 left position first and then right position (open→closed), second control valve 722 right position first and then left position (closed→open).

[0088] Process: the hydraulic oil in the rodless cavity 11 is first absorbed by the accumulator 711 to quickly reduce the speed of the mold opening and closing hydraulic cylinder 1, when reaching the preset speed or position, the accumulator 711 passage is closed, and the super capacitor passage is opened, the oil is regenerated and recovered to the super capacitor group 729 by the hydraulic motor / pump integrated machine 721; through the electromagnetic torque closed loop, the mold opening and closing hydraulic cylinder 1 realizes flexible deceleration and positioning stop at the terminal, as shown below Figure 8 as shown.

[0089] Energy migration before shutdown or maintenance:

[0090] Valve position: to reduce the risk of downtime and accumulator 711 static leakage, the first control valve 712, the second control valve 722 can be placed at the left position (open) at the same time. At the same time, the motor and hydraulic pump of the main oil circuit are closed, and the residual pressure of the accumulator 711 is used to drive the hydraulic motor / pump integrated machine 721, so as to convert the potential energy of the accumulator 711 into electrical energy and store it in the super capacitor group 729, which is convenient for cross-device sharing and subsequent reuse, as shown below Figure 9 .

[0091] This embodiment realizes 800T clamping force of die casting machine, and the above scheme is implemented. The parameters of the die casting machine are as follows:

[0092] Bore: 280mm; rod diameter: 196mm; cross-sectional area of rodless cavity 11 : 0.061575 ; cross-sectional area of rod cavity 12 : 0.031327 ; the working cycle of the die casting machine is 40S.

[0093] Speed requirement:

[0094] Height section: ; middle section deceleration: ;

[0095] Approximate calculation by uniform deceleration process: ;

[0096] End deceleration: ;

[0097] Approximate calculation by uniform deceleration process: .

[0098] Pressure requirement:

[0099] Clamping end ; opening end ;

[0100] Middle section uniform ;

[0101] The conversion efficiency of each part is as follows:

[0102] Accumulator 711 (hydraulic air bag):

[0103] Charging efficiency: ; energy release efficiency: ;

[0104] Electric side (battery / super capacitor and M / G):

[0105] Input efficiency: ; output efficiency: ;

[0106] The calculation results are as follows:

[0107] The operation of the open-close mold hydraulic cylinder 1 is divided into six stages, wherein the stages of high-speed mold opening and high-speed mold closing have no energy recovery, so only the remaining four stages need to be considered, and the recovered energy of the four stages is as follows:

[0108] End buffer section of mold opening:

[0109] ;

[0110] End buffer section of mold closing:

[0111] ;

[0112] Middle section of mold opening: ;

[0113] Middle section of mold closing: ;

[0114] The total energy is as follows: ;

[0115] The case accumulator 711 and the electric side proportion of 7:3 proportion distribution obtains:

[0116] ;

[0117] ;

[0118] ;

[0119] ;

[0120] 68.15KJ is distributed to two sections as injection power in the high-speed section, which directly offsets the main pump power supply.

[0121] The energy recovery rate and utilization rate are as follows:

[0122] The total energy recovery rate (stored in the accumulator 711 and the capacitor):

[0123] ;

[0124] The total utilization rate of recovered energy (releasable energy): .

[0125] The baseline main pump rated power before optimization: ;

[0126] By adopting the technical scheme of the embodiment, the main pump rated power can be , the motor, frequency converter and power distribution capacity are degraded and the cost is reduced, which has positive effects on system starting impact and power grid power demand. At the same time, the reduction of main pump power and power loss during equipment overflow further reduces the power consumption.

[0127] In the embodiment, the oil volume is 200L, the mass is about 180kg according to ρ≈0.9kg / L, cp is the specific heat of oil, cp≈1.9kJ / (kg·K), and the beat N=1.5 times / min (period 40s).

[0128] Baseline oil side heat per minute: ;

[0129] ;

[0130] After adopting the technical scheme of the embodiment, the oil side heat per minute is as follows:

[0131] ;

[0132] ;

[0133] The temperature rise difference is about 0.339K / min, and the temperature rise difference in 60 minutes is about 20.34K. The technical scheme of the embodiment can significantly reduce the burden of the cooling system.

[0134] The oil side heat generation is reduced from to , which is 89.2% lower than the baseline. The cooling load is reduced by 1.93kW, the oil temperature is more stable, and the leakage and wear are reduced.

[0135] High-speed mold opening / closing subsystem power saving: ; in a 40s working cycle: , during the mold opening / closing process, the direct power saving is 15.95%, and after superimposing energy recovery, the reduction of hydraulic oil temperature rise leads to the reduction of cooling system (fan / pump) power consumption, and the system energy saving rate will be further improved.

[0136] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application but not to limit it, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that: it can still modify or equivalently replace the technical solutions of the present application, and these modifications or equivalent replacements also cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A die casting machine mold opening and closing kinetic energy recovery system comprising a mold opening and closing hydraulic cylinder, a main oil pump, a first directional control valve, and a second directional control valve, the mold opening and closing hydraulic cylinder having a rodless chamber and a rod chamber, the first directional control valve being provided on a first passage between the main oil pump and the rodless chamber, the second directional control valve being provided on a second passage between the first directional control valve and the rod chamber, characterized in that: The hybrid energy recovery unit comprises a peak-holding hydraulic energy storage passage and a speed control electric side energy storage passage, a connection point of the peak-holding hydraulic energy storage passage and the speed control electric side energy storage passage is connected with the deceleration passage, and the first reversing valve and the second reversing valve are arranged on the deceleration passage; the connection point of the peak-holding hydraulic energy storage passage and the speed control electric side energy storage passage is connected with one end of the acceleration passage, the other end of the acceleration passage is connected on the first passage between the first reversing valve and the main oil pump, and the acceleration passage is provided with the third reversing valve in parallel, for controlling the opening and closing of the cartridge valve on the acceleration passage; The control unit is used for collecting operation data of the mold opening and closing hydraulic cylinder and the hybrid energy recovery unit, and switching the peak-holding hydraulic energy storage passage and the speed control electric side energy storage passage according to the operation data; In the energy recovery stage, the peak-holding hydraulic energy storage passage is first opened, so that the return oil is directly charged to the accumulator; when the movable mold reaches a preset displacement or speed, and the precision deceleration control needs to be set, the speed control electric side energy storage passage is switched to be opened, so that the return oil drives the hydraulic motor / pump integrated machine, and the converted electric energy is stored in the super capacitor group; In the energy release stage, the first control valve is preferentially opened, so that the accumulator releases energy to the mold opening and closing hydraulic cylinder to provide peak flow; when the accumulator pressure drops to a lower threshold, the speed control electric side energy storage passage drives the hydraulic motor / pump integrated machine through inversion to supplement power.

2. The die casting machine mold opening and closing kinetic energy recovery system in accordance with claim 1, characterized by: The peak-holding hydraulic energy storage passage is provided with at least one accumulator and a first control valve, the first control valve is used for controlling the direct charging and energy release of the accumulator, a safety passage is connected between the accumulator and the first control valve, and a safety valve is arranged at the tail end of the safety passage, for limiting the maximum pressure of the accumulator.

3. The die casting machine mold opening and closing kinetic energy recovery system in accordance with claim 2, characterized by: The speed control electric side energy storage passage is provided with a hydraulic motor / pump integrated machine and a second control valve, the hydraulic motor / pump integrated machine is connected with a bidirectional three-phase active rectifier module, the bidirectional three-phase active rectifier module is connected with a filter, the filter is connected with a first DC-DC conversion module, the first DC-DC conversion module and the filter are connected with a high-voltage contactor, the high-voltage contactor is connected with a super capacitor group and is provided with a brake resistor module, and the super capacitor group is connected with the bidirectional three-phase active rectifier module through a second DC-DC conversion module.

4. The die casting machine mold opening and closing kinetic energy recovery system in accordance with claim 3, characterized by: The super capacitor group is provided with a super capacitor management module, the super capacitor management module is used for voltage equalization, temperature monitoring and health state monitoring and evaluation of the super capacitor group, the super capacitor group is connected with a direct current bus, and the direct current bus is connected with an energy interface of an energy consumption device to realize energy sharing.

5. The die casting machine mold opening and closing kinetic energy recovery system in accordance with claim 3, characterized by: The deceleration passage and the acceleration passage are each provided with a check valve or a shuttle valve for preventing mutual backflow of electro-hydraulic passages.

6. The die casting machine mold opening and closing kinetic energy recovery system in accordance with claim 3, characterized by: The first passage, the deceleration passage and the acceleration passage are each connected with an overflow valve.

7. The die casting machine mold opening and closing kinetic energy recovery system in accordance with claim 3, characterized by: The control unit comprises a pressure collection module, an electric parameter collection module, a mold opening and closing parameter collection module, a temperature collection module and a control module; the pressure collection module, the electric parameter collection module, the mold opening and closing parameter collection module and the temperature collection module are connected with the control module, for controlling the states of corresponding components according to collected data; The pressure collection module is used for collecting accumulator pressure; The electric parameter collection module is used for collecting voltage of a direct current bus; The opening and closing mold parameter acquisition module is used for acquiring displacement and speed of opening and closing mold The temperature acquisition module is used for acquiring oil temperature and environment temperature, which is used for subsequent temperature compensation of accumulator pressure value; According to the accumulator pressure window and the DC bus voltage window, threshold triggering soft switching and power distribution are implemented; When the DC bus is overvoltage and the first DC-DC conversion module has limited power, the brake resistance module is put into operation to protect the super capacitor group.

8. The recovery method of the die casting machine mold opening and closing kinetic energy recovery system according to claim 7, characterized in that, The specific steps are as follows: Step S1: According to the die casting machine speed-time curve, the opening and closing mold cycle is divided into working conditions; Step S2: According to the working condition division, the switching strategy is set; Step S3: According to the switching strategy and the collected operation data, the switching of the peak holding hydraulic energy storage path and the speed control electric side energy storage path is carried out, and the energy recovery under different working conditions is realized.

9. The recovery method of a die casting machine opening and closing mold kinetic energy recovery system according to claim 8, characterized in that: The opening and closing mold cycle is divided into six working conditions, which are high-speed closing mold T1, low-speed closing mold T2, closing mold T3, low-speed opening mold T4, high-speed opening mold T5 and opening mold T6; The opening mold includes the high-speed to low-speed transition section T6-1 and the opening mold terminal deceleration section T6-2.

10. The method of claim 9, wherein: In the low-speed closing mold T2 and high-speed to low-speed transition section T6-1 stage, the return oil enters the accumulator in the peak holding hydraulic energy storage path through the deceleration channel, forming a back pressure state; When the moving die reaches the preset speed or displacement, and the precision deceleration control needs to be set, the speed control electric side energy storage path is switched, and the energy is converted into electric energy by the hydraulic motor / pump integrated machine and stored in the super capacitor group; In the closing mold T3, low-speed opening mold T4 and opening mold terminal deceleration section T6-2 stage, the return oil enters the switched speed control electric side energy storage path through the deceleration channel, and the electromagnetic torque of the hydraulic motor / pump integrated machine is closed loop tracked according to the deceleration or back pressure, so as to realize the speed control and energy recovery of the moving die speed curve; In the high-speed closing mold T1 and high-speed opening mold T5 stage, the accumulator releases energy to hold the peak, and establishes a high-speed running state; When the accumulator pressure drops to the lower limit value, the speed control electric side energy storage path is switched, and the hydraulic motor / pump integrated machine is driven by the super capacitor group to supplement energy; Threshold soft switching and power distribution are implemented based on the accumulator pressure window and the DC bus voltage window; When the bus voltage exceeds the first threshold value, the power is limited first, and when it still exceeds the threshold value, the brake resistance module is put into operation to absorb the excess energy; Before shutdown or maintenance, the first control valve and the second control valve enter the safe working condition, and the temperature of the super capacitor group is within the set temperature range, so that the residual energy of the accumulator is converted by the hydraulic motor / pump integrated machine and stored in the super capacitor group, and the high-voltage contactor is disconnected to make the DC bus power off; When the temperature of the super capacitor group is not within the set temperature range, the brake resistance module is used for energy release.

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