CN201752921U - Servo motor control system of full-electric injection machine - Google Patents

Abstract

The utility model discloses a servo motor control system of a full-electric injection machine, which includes an injection machine computer controller, servo motor controllers and a PLC controller; the computer controller is connected with the servo motor controllers through a CAN (controller area network) bus; the servo motor controller is connected with a servo motor; the computer controller is connected with the PLC (programmable logic controller) controller; the servo motor controller refer to a die opening and closing servo motor controller, an injection servo motor controller, a smelting and pressure maintaining servo motor controller and an ejection servo motor controller; the servo motor refer to a die opening and closing servo motor, an injection servo motor, a smelting and pressure maintaining servo motor and an ejection servo motor. The servo motor control system of the full-electric injection machine can implement synchronization control on simultaneously implemented techniques by implementing die opening and closing control, injection control, smelting control, pressure maintaining control, ejection control, ejection platform movable control and die modulating control on the motor of the electric injection machine, and save the production time by one third.

Description

Servo motor control system of full-electric injection molding machine

Technical Field

The utility model relates to an electric injection molding machine field, in particular to servo motor's of full-electric injection molding machine control system.

Background

A plastic injection molding machine is a main molding device for manufacturing various plastic products from thermoplastic plastics or thermosetting plastics. The working process of a general plastic injection molding machine (hereinafter referred to as an injection molding machine) is as follows: granular or powdered plastic is fed from the hopper of injection moulding machine into heated charging barrel with a certain temp., and after being heated and molten to become fluid state, it is pushed by screw to pass through the nozzle at the front end of charging barrel and injected into closed mould with lower temp., and under the condition of pressure, the molten plastic is cooled and solidified to obtain the plastic product.

Although the existing hydraulic injection molding machine driving device can generate larger acting force to drive a mechanical structure to work and realize stable transmission, the driving device also has a plurality of defects, such as high energy consumption, large noise, serious pollution, low production efficiency and the like. The presence of these factors has made all-electric injection molding machines desirable. In the present day that the energy is increasingly deficient and the ecological environment is increasingly worsened, the research and development of the control system and the control method of the environment-friendly 'green' full-electric injection molding machine are increasingly urgent and important, and the control use of the servo motor is particularly important.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a full-electric injection molding machine servo motor's control system and control method, through the utility model discloses to full-electric injection molding machine servo motor's control, make it have energy saving, clean, the noise is low, the precision is high, repeatability is high, speed control range is wide, the responsiveness is good, advantages such as production efficiency height.

The purpose of the utility model is realized through the following technical scheme: a servo motor control system of a full-electric injection molding machine is characterized by comprising an injection molding machine computer controller, a servo motor controller and a PLC (programmable logic controller); the computer controller is connected with the servo motor controller through a CAN bus, the servo motor controller is connected with the servo motor, and the computer controller is connected with the PLC; the servo motor controller is an opening and closing die servo motor controller, a glue injection servo motor controller, a glue melting and pressure maintaining servo motor controller and an ejection servo motor controller; the servo motors are an opening and closing die servo motor, a glue injection servo motor, a glue melting and pressure maintaining servo motor and an ejection servo motor.

In order to better realize the utility model, the servo motor control system also comprises an LCD display module, a keyboard module and an Ethernet control chip which are respectively connected with the injection molding machine computer controller; the injection molding machine computer controller adopts an AMD microprocessor, and the servo motor controller adopts a DSP controller (adopting a TMS320F28335 chip).

Penetrate and glue among servo motor controller and the molten glue pressurize servo motor controller, pressure sensor is connected to the SCI module of DSP controller, the JTAG module connection control emulation ware LED lamp of DSP controller, the IO module connection control warning output location of DSP controller accomplishes the signal LED lamp, outside PWM unit is connected to 2 EVA/B modules of DSP controller, outside PWM unit passes through IPM power drive board respectively with penetrate to glue servo motor, the molten glue pressurize servo motor is connected, penetrate to glue servo motor and molten glue pressurize motor and give ADC module feedback current signal of DSP controller through current sensor respectively, penetrate to glue servo motor and molten glue pressurize servo motor and give the QEP module feedback signal of DSP controller through the code wheel respectively.

In the open-close die servo motor controller and the ejection servo motor controller, one output end of a DSP controller is respectively connected to an injection molding machine computer controller and an emulator through a CAN bus communication module and a JTAG interface of the DSP controller, the other output end of the DSP controller is sequentially connected with an IPM power drive board and a servo motor through an event manager EVA/B of the DSP controller, the servo motor is connected to an analog-to-digital conversion module ADC of a chip through a current sensor, and the servo motor is also connected with a quadrature encoder unit QEP of the chip through a code disc; the servo motor refers to an opening and closing motor and an ejection motor.

The control method of the servo motor control system of the full-electric injection molding machine is characterized in that the servo motor of the electric injection molding machine is subjected to mold opening and closing control, glue melting control, glue injection control, pressure maintaining control, ejection control, injection table movement control and mold adjustment control, so that the injection molding function is completed by the driving motor, and the process procedures which can be simultaneously performed are synchronously controlled, so that the purpose of saving the production time is realized.

The control method comprises the following steps:

step one, selecting a working mode of a servo motor of the full-electric injection molding machine: manual, semi-automatic or fully automatic;

secondly, starting a control method of the servo motor control system according to a selected mode, wherein the manual mode is that parameters are manually input to independently control the actions of opening and closing the mold, advancing the injection platform, melting glue, injecting and ejecting according to the cyclic process requirement of the injection molding action; the semi-automatic working mode means that a servo motor control system completes single cycle action according to a control method according to the technological requirements of injection molding action; the full-automatic working mode is that the servo motor control system completes multiple circulating actions according to the process requirement of single circulating action according to the injection molding action process.

The second step of completing the single cycle action according to the control method comprises the following steps:

step I, closing the safety door;

step II, controlling a glue injection servo motor, and simultaneously controlling die assembly of an opening and closing servo motor;

step III, performing pressure maintaining control on the glue melting pressure maintaining servo motor;

step IV, performing melt glue control on a melt glue pressure maintaining servo motor, and performing die opening control on an opening and closing die servo motor and ejection control on an ejection servo motor at the same time;

and V, opening the safety door, and finishing.

The control of the injection servo motor and the control of the melt glue pressure maintaining motor refer to the following steps:

the glue injection process comprises the following steps: the glue injection motor does not work, the glue injection motor is started to drive the glue injection nut to rotate, the positions of the glue injection motor and the glue injection nut are not moved, the glue injection nut drives the ball screw to advance, meanwhile, the ball screw pushes the screw, the glue injection nut and the glue injection motor to advance, and the glue injection motor is stopped until the glue injection process is finished;

the glue melting process comprises the following steps:

the ith step: the glue melting motor is started, the glue melting motor drives the glue melting nut to rotate, the glue melting nut drives the screw to rotate, and a bearing is arranged at the joint of the screw and the ball screw, so that the screw can rotate freely without driving the ball screw to rotate;

step ii: the screw rod pushes the material forwards and heats the material to melt the material at the same time through rotation, the material is continuously conveyed to the head of the screw rod, the molten material gathered in the material storage area of the machine barrel generates certain pressure, the pressure is increased, the screw rod is pushed, but the pressure between the screw rod and the ball screw rod is increased because the ball screw rod tightly pushes the screw rod, and at the moment, a pressure sensor positioned at the connection part of the screw rod and the ball screw rod transmits a pressure measurement value to the DSP controller;

step iii: the DSP controller is compared with a pressure set value;

step iv: when the measured value of the pressure sensor exceeds a set value, the DSP controller controls the glue injection motor and the glue injection nut to start to rotate reversely, the positions of the glue injection motor and the glue injection nut do not move, the ball screw moves backwards according to a set speed, the screw rod also moves backwards, the glue melting nut and the glue melting motor drive the screw rod and simultaneously move backwards, and the ball screw keeps a certain pressure on the screw rod;

the v step: stopping the glue injection motor and the glue melting motor until the set retreating displacement is met, and finishing the injection amount and the reset of the ball screw, so as to prepare for next glue injection;

in the glue melting process: the equation of the motion function of the screw rod retreating is as follows:

m: the total weight of the screw, the glue melting nut and the glue melting motor; g: acceleration of gravity; v: the screw retreating speed; f_a: pressure generated by melting the material; f_B: resistance of the ball screw; f_L: reaction force of the molten material; f: friction force.

The current relation between the glue melting motor and the glue injection motor is as follows:

the current loop open loop transfer function is:

K_vvoltage amplification factor, K, of an inverter of an external PWM unit_mAs a current feedback factor, T_vIs the inverter time constant, T_v＝1/f_v，f_vThe inverter has working frequency, s is differential, two motor armature loops are composed of a resistor R and an inductor L and are a first-order inertia link, T_oiSampling the filter time constant for the current, wherein T_oiAnd T_vAre all small time constants, equivalently one time constant T_ov＝T_oi+T_vAnd is also T_LL/R is the motor armature loop time constant, and the equation (1) is equivalent to:

the PI regulator of the motor corrects the current into an I-type system with better dynamic performance, and the transfer function of the regulator is

K_p，τ_cProportional coefficient and integral time constant of the PI regulator,

eliminating the pole of large time constant of the controlled object by the zero point of the current loop PI regulator, and taking tau_c＝L/R＝T_LTherefore, the open loop transfer function of the current loop corrected by the PI regulator is

(2) The formula reduces to a typical type I system:

wherein K is K_pK_v/(Rτ_c)；

The current loop closed loop transfer function is then:

$C\left(s\right)=\frac{G\left(s\right)}{1+G\left(s\right)}$

<math><mrow><mo>=</mo><mfrac><mrow><msub><mi>K</mi><mi>v</mi></msub><msub><mi>K</mi><mi>p</mi></msub><msub><mi>K</mi><mi>m</mi></msub></mrow><mrow><msub><mi>&tau;</mi><mi>c</mi></msub><mi>s</mi><mrow><mo>(</mo><msub><mi>T</mi><mi>ov</mi></msub><mi>s</mi><mo>+</mo><mn>1</mn><mo>)</mo></mrow><mo>+</mo><msub><mi>K</mi><mi>v</mi></msub><msub><mi>K</mi><mi>p</mi></msub><msub><mi>K</mi><mi>m</mi></msub></mrow></mfrac></mrow></math>

$=\frac{K}{s(T_{\mathrm{ov}}s+1)+K}$

<math><mrow><mo>=</mo><mfrac><msup><msub><mi>&omega;</mi><mi>n</mi></msub><mn>2</mn></msup><mrow><msup><mi>s</mi><mn>2</mn></msup><mo>+</mo><mn>2</mn><mi>&xi;</mi><msub><mi>&omega;</mi><mi>n</mi></msub><mi>s</mi><mo>+</mo><msup><msub><mi>&omega;</mi><mi>n</mi></msub><mn>2</mn></msup></mrow></mfrac></mrow></math>

ω n is cut-off frequency, and damping ratio ξ is 0.707 according to the optimal performance index of the second-order system, namelyTo find K, τ_c＝L/R＝T_LDetermining K_p，τ_c；

The current loop is an inner loop of the speed loop, and under the condition of obtaining a transfer function of the current loop, the transfer function of the speed loop is closed:

beta is the voltage vector, K_fnFor the velocity feedback coefficient, T_mIs the electromechanical time constant of the motor, K_ΦAs a result of the potential coefficient of the motor,

T_onfor the rotational speed feedback filtering time constant,

T_land T_onAre all small time constants, equivalently one time constant T_fs＝T_l+T_onThe inertia link of (2), the speed loop control object is:

<math><mrow><msub><mi>C</mi><mi>i</mi></msub><mrow><mo>(</mo><mi>s</mi><mo>)</mo></mrow><mo>=</mo><mfrac><mrow><msub><mi>K</mi><mi>l</mi></msub><mi>R</mi><msub><mi>K</mi><mi>fn</mi></msub></mrow><mrow><msub><mi>T</mi><mi>m</mi></msub><msub><mi>K</mi><mi>&Phi;</mi></msub><mi>s</mi><mrow><mo>(</mo><msub><mi>T</mi><mi>fs</mi></msub><mi>s</mi><mo>+</mo><mn>1</mn><mo>)</mo></mrow></mrow></mfrac><mo>=</mo><mfrac><mrow><msub><mi>K</mi><mi>l</mi></msub><mi>R</mi><msub><mi>K</mi><mi>fn</mi></msub><mo>/</mo><msub><mi>T</mi><mi>m</mi></msub><msub><mi>K</mi><mi>&Phi;</mi></msub></mrow><mrow><mi>s</mi><mrow><mo>(</mo><msub><mi>T</mi><mi>fs</mi></msub><mi>s</mi><mo>+</mo><mn>1</mn><mo>)</mo></mrow></mrow></mfrac><mo>=</mo><mfrac><msub><mi>K</mi><mi>on</mi></msub><mrow><mi>s</mi><mrow><mo>(</mo><msub><mi>T</mi><mi>fs</mi></msub><mi>s</mi><mo>+</mo><mn>1</mn><mo>)</mo></mrow></mrow></mfrac></mrow></math>

the speed loop is corrected to a typical type II system, the speed loop regulator is a PI regulator, and the transfer function is

The open-loop transfer function of the speed loop after being regulated by the PI regulator is as follows:

<math><mrow><msub><mi>C</mi><mi>s</mi></msub><mrow><mo>(</mo><mi>s</mi><mo>)</mo></mrow><mo>=</mo><mfrac><mrow><msub><mi>K</mi><mi>ps</mi></msub><mrow><mo>(</mo><msub><mi>&tau;</mi><mi>s</mi></msub><mi>s</mi><mo>+</mo><mn>1</mn><mo>)</mo></mrow><msub><mi>K</mi><mi>c</mi></msub></mrow><mrow><msub><mi>&tau;</mi><mi>s</mi></msub><mi>J</mi><msup><mi>s</mi><mn>2</mn></msup><mrow><mo>(</mo><mn>2</mn><msub><mi>T</mi><mi>fs</mi></msub><mi>s</mi><mo>+</mo><mn>1</mn><mo>)</mo></mrow></mrow></mfrac><mo>,</mo></mrow></math>

kc is a proportionality coefficient and is a constant value, J is the rotor inertia of the motor and is a constant value, after the constant value is corrected by a PI regulator, a speed ring is a typical II-type system, and the open-loop transfer function of the speed ring is as follows:

wherein, K_N＝K_onK_ps/τ_sDefining the width of the intermediate frequency band h ═ tau in the open-loop amplitude-frequency characteristic for the open-loop amplification factor of the speed loop_s/T_fsThe dynamic performance index of a typical II type system is determined, h is increased, the overshoot is reduced, but the change of the adjusting time along with h is not monotonous, when h is 5, the adjusting time is shortest, the dynamic response is fastest, and a proper cut-off frequency omega is selected_nCalculating to obtain tau_sAnd K_ps：

<math><mfenced open='{' close=''><mtable><mtr><mtd><msub><mi>&tau;</mi><mi>s</mi></msub><mo>=</mo><mi>h</mi><mo>*</mo><msub><mi>T</mi><mi>fs</mi></msub></mtd></mtr><mtr><mtd><msub><mi>K</mi><mi>ps</mi></msub><mo>=</mo><mfrac><mrow><mi>h</mi><mo>+</mo><mn>1</mn></mrow><mrow><mn>2</mn><mi>h</mi></mrow></mfrac><mo>*</mo><mfrac><mrow><msub><mi>T</mi><mi>m</mi></msub><msub><mi>K</mi><mi>&Phi;</mi></msub></mrow><mrow><msub><mi>T</mi><mi>fs</mi></msub><msub><mi>K</mi><mi>l</mi></msub><mi>R</mi><msub><mi>K</mi><mi>fn</mi></msub></mrow></mfrac></mtd></mtr></mtable></mfenced></math>

The time period and the gain of the speed loop are tau_WAnd K_WThe position control loop adopts proportional adjustmentThe number of the node and the proportional regulator is set to K_θThe closed loop transfer function of the position loop is:

<math><mrow><msub><mi>G</mi><mi>p</mi></msub><mrow><mo>(</mo><mi>s</mi><mo>)</mo></mrow><mo>=</mo><mfrac><mi>&theta;</mi><msup><mi>&theta;</mi><mo>*</mo></msup></mfrac><mo>=</mo><mfrac><mrow><msub><mi>K</mi><mi>&theta;</mi></msub><msub><mi>K</mi><mi>W</mi></msub><mo>/</mo><msub><mi>&tau;</mi><mi>W</mi></msub></mrow><mrow><msup><mi>s</mi><mn>2</mn></msup><mo>+</mo><mi>s</mi><mo>/</mo><msub><mi>&tau;</mi><mi>W</mi></msub><mo>+</mo><msub><mi>K</mi><mi>&theta;</mi></msub><msub><mi>K</mi><mi>W</mi></msub><mo>/</mo><msub><mi>&tau;</mi><mi>W</mi></msub></mrow></mfrac><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>3</mn><mo>)</mo></mrow></mrow></math>

theta is position feedback, theta^*For a given position, the position loop gain is set to K_p＝K_θK_WThen, the formula (3) is:

wherein, <math><mrow><mi>&xi;</mi><mo>=</mo><mfrac><mn>1</mn><mn>2</mn></mfrac><msqrt><mfrac><mn>1</mn><mrow><msub><mi>K</mi><mi>p</mi></msub><msub><mi>&tau;</mi><mi>W</mi></msub></mrow></mfrac></msqrt><mo>,</mo></mrow></math> <math><mrow><msub><mi>&omega;</mi><mi>n</mi></msub><mo>=</mo><msqrt><mfrac><msub><mi>K</mi><mi>p</mi></msub><msub><mi>&tau;</mi><mi>W</mi></msub></mfrac></msqrt></mrow></math>

the position servo system is in a critical damping state or an under-damping state, and the cut-off frequency f of a velocity link is corrected_W＝1/τ_WAfter determination, the following steps are determined by ξ ≧ 1: k_p≤1/(4τ_W)，K_p＝1/(4τ_W) The loop gain is controlled for the optimal position.

The control of the split-die motor and the ejection motor comprises the following steps:

step 1, determining a ball screw, a die opening and closing motor and an ejection motor which are selected by a die closing device and an ejection device according to the die moving speed characteristic and the force increasing characteristic of the die opening and closing process of the double-toggle mechanism by adopting a five-hinge die closing double-toggle mechanism and a crank slide block ejection mechanism;

and step 2, controlling the die opening and closing motor and the ejection motor and setting perfect die protection measures according to the load characteristics and the process requirements of the die opening and closing motor and the ejection motor, wherein the steps comprise:

(1) in the mold closing process, firstly, the mold closing is quickly carried out at low pressure, when the movable mold plate is close to the fixed mold plate, the mold closing is automatically switched to the low-speed mold closing, and after the fact that no foreign matter exists in the mold cavity is determined, the mold is switched to the high pressure again to close the mold; in the mold closing process, in order to prevent the overflow of mold materials, a large mold closing force needs to be applied, and a mold opening and closing motor is controlled by torque in the process;

(2) in the mold opening process, firstly, the mold cavity surface of the injection part cooling mold is ensured to be separated from the position of the guide pillar, then the movable mold plate moves at a constant speed to open the mold quickly, and the movable mold plate stops at a slow speed when approaching the starting position of the movable mold plate;

(3) the ejection speed is adjusted by adjusting the rotating speed of the ejection motor, so that the in-mold product is accurately and stably ejected;

the ball screw, the die opening and closing motor and the ejection motor which are selected by the die closing device and the ejection device are determined in the step 1: firstly, determining the shaft diameter, the lead, the length of a lead screw, the shaft diameter and the precision grade of the lead screw according to the translation working condition of a five-hinge die-closing double-crank elbow die-closing mechanism; and selecting a mold opening and closing motor and an ejection motor by comprehensively considering the required mold locking force, the mold moving speed, the stroke ratio, the ball screw lead and the transmission ratio of the belt transmission device.

Determining whether a foreign object is in the fixed die cavity in the step 2 (1) means that a detection interval is set at a position close to the fixed die plate, and whether an obstacle exists or not is determined by detecting whether the change of the load current of the die opening and closing motor exceeds the limit;

the step 2 (2) of ensuring that the cavity surface of the injection part cooling mold is separated from the guide post is set to be the position when the guide post is contacted with the mold on the fixed side;

the mold closing process in the step 2 and the step (1) comprises the following steps:

firstly, moving from a mold opening end position to a mold closing speed change position, namely a mold closing speed 1 stage;

moving from the mold closing speed changing position to the mold protecting position, wherein the mold closing speed is 2 sections, and the sections move at high speed and low pressure;

thirdly, moving from the mold protection position to the mold contact position, namely a mold closing speed 3 section, wherein the section is a mold protection area, if the current sensor monitors that the current of the section is increased compared with a common current curve during mold closing, the residual plastic on the end face of the mold is not taken out, the mold closing process is stopped, and the mold is immediately opened;

fourthly, moving the mold from the mold protection area to the mold for closing, and applying maximum pressure to mold locking;

the mold moving speed in the mold opening and closing process in the step 2 is obtained according to the following method:

firstly, moving template stroke

According to the structural analysis, the moving stroke S of the movable template_mThe displacement of the B point of the hinged support can be characterized as follows:

<math><mrow><msub><mi>S</mi><mi>m</mi></msub><mo>=</mo><msub><mi>L</mi><msub><mi>AB</mi><mn>0</mn></msub></msub><mi>cos</mi><msub><mi>&gamma;</mi><mn>0</mn></msub><mo>-</mo><msub><mi>L</mi><msub><mi>AB</mi><mn>1</mn></msub></msub><mi>cos</mi><msub><mi>&gamma;</mi><mn>1</mn></msub><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>4</mn><mo>)</mo></mrow></mrow></math>

in the formula (4)Is the center line of hinge A, B in the final lock position.

$L_{{\mathrm{AB}}_O}={\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HSA00000220249300031.png"\; state="\{\{state\}\}">L</figure-callout>}}_1+L_2---\left(5\right)$

<math><mrow><msub><mi>L</mi><msub><mi>AB</mi><mn>1</mn></msub></msub><mo>=</mo><msub><mi>L</mi><mn>1</mn></msub><mi>cos</mi><msub><mi>&alpha;</mi><mn>1</mn></msub><mo>+</mo><msub><mi>L</mi><mn>2</mn></msub><mi>cos</mi><msub><mi>&beta;</mi><mn>1</mn></msub><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>6</mn><mo>)</mo></mrow></mrow></math>

Elbow length ratio λ L₁/L₂According to the sine law

Thus, can obtain <math><mrow><msub><mi>S</mi><mi>m</mi></msub><mo>=</mo><msub><mi>L</mi><mn>1</mn></msub><mrow><mo>(</mo><mn>1</mn><mo>-</mo><mi>cos</mi><msub><mi>&alpha;</mi><mn>1</mn></msub><mo>+</mo><mfrac><msqrt><mn>1</mn><mo>-</mo><msup><mi>&lambda;</mi><mn>2</mn></msup><msup><mi>sin</mi><mn>2</mn></msup><msub><mi>&alpha;</mi><mn>1</mn></msub></msqrt><mi>&lambda;</mi></mfrac><mo>)</mo></mrow><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>7</mn><mo>)</mo></mrow></mrow></math>

<math><mrow><msub><mi>&alpha;</mi><mn>1</mn></msub><mo>=</mo><msup><mi>cos</mi><mrow><mo>-</mo><mn>1</mn></mrow></msup><mo>[</mo><mn>1</mn><mo>-</mo><mfrac><mrow><msub><mi>S</mi><mi>m</mi></msub><mrow><mo>(</mo><mn>2</mn><msub><mi>L</mi><mn>1</mn></msub><mo>-</mo><msub><mi>S</mi><mi>m</mi></msub><mi>&lambda;</mi><mo>)</mo></mrow></mrow><mrow><mn>2</mn><msub><mi>L</mi><mn>1</mn></msub><mrow><mo>(</mo><msub><mi>L</mi><mn>1</mn></msub><mo>+</mo><mi>&lambda;</mi><msub><mi>L</mi><mn>1</mn></msub><mo>-</mo><mi>&lambda;</mi><msub><mi>S</mi><mi>m</mi></msub><mo>)</mo></mrow></mrow></mfrac><mo>]</mo><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>8</mn><mo>)</mo></mrow></mrow></math>

② stroke S of piston rod_gSum stroke ratio K_S

Piston rod stroke is a term followed for hydraulic clamping devices, in which a motor drives a clamping device S_gRepresents the travel of the crosshead, characterized by the amount of movement of the hinge E on the crosshead:

ratio of die plate stroke to crosshead strokeCalled stroke ratio K_S＝S_M/S_g(12)

K_SThe ratio of the mold moving speed to the crosshead moving speed is reflected, and the energy consumption of the machine table is also reflected;

③ die-moving speed V_mAnd coefficient of variation of velocity K_V

The mold-moving speed of the toggle rod type mold-closing mechanism can be controlled, if the friction loss is neglected, the power input to the mold-closing mechanism is equal to the power output according to the energy conservation theorem, namely

P_B·V_B＝P_M·V_M (13)

So that the moving speed of the template can be obtained

The utility model discloses for prior art have following advantage and effect:

1. the utility model discloses rely on four servo motor of DSP controller to control, can realize the efficiency optimization of the process of moulding plastics, not only the melten gel measurement is of high quality, and the melten gel measurement precision is high, and the time that shortens the no-load stroke has both been considered in the mould process of opening and shutting, considers the buffering requirement that the mould opened and close the process again, has avoided the defect that the goods overflow limit or goods precision descend, simple structure, simple to operate, transmission precision are high moreover, and the noise is low.

2. Through the utility model discloses a control system and control method realize that the technological process of electric injection molding machine accomplishes the function of moulding plastics by six independent motor drives, drive injection molding machine open and shut mould control, melten gel control, penetrate gluey control, pressurize control, ejection control, penetrate a mobile control and transfer mould control. Compared with a hydraulic injection molding machine, the two processes can be operated simultaneously. If the mold opening can be controlled in an ejection mode, the glue melting process needs the matching of a glue melting motor and a glue injection motor, and the like, and compared with a hydraulic injection molding machine for injecting products, the one-third cycle time can be saved.

Drawings

FIG. 1 is a schematic structural view of an all-electric injection molding machine according to the present invention;

wherein: 1. the automatic mold adjusting device comprises a ball screw 2, a ball screw nut 3, a movable support plate 4, a glue melting servo motor 5, a toothed belt 6, a screw 7, a ball screw 8, an ejection servo motor 9, a ball screw 10, a mold locking servo motor 11, a servo motor torque control 12, a toothed belt 13, a pressure sensor 14, a glue injection servo motor 15, a slide adjusting screw 16, a slide adjusting Y motor 17, a core-pulling servo motor 18, a ball screw nut 19, a crank arm straightening detection point 20, a crank arm 21, a ball screw nut 22 and a mold adjusting Y motor 23;

FIG. 2 is the injection molding process flow of the full-electric injection molding machine of the utility model;

FIG. 3 is a block diagram of the servo motor and PLC control system of the all-electric injection molding machine of the present invention;

FIG. 4 is a block diagram of the overall structure of the control system of the all-electric injection molding machine of the present invention;

FIG. 5 is a circuit diagram of input and output points of the I/O board of the PLC controller in the all-electric injection molding machine of the present invention;

fig. 6 is a core control task block diagram of a computer controller in the all-electric injection molding machine of the present invention;

FIG. 7 is a schematic view of a process cycle for an all-electric injection molding machine;

FIG. 8 is a schematic diagram of the motion of a double toggle mechanism employed by the mold opening and closing mechanism of the all-electric injection molding machine;

fig. 9 is a detailed connection block diagram of the control system and the servo motor of the all-electric injection molding machine.

Detailed Description

The present invention will be further explained with reference to the drawings and examples. However, the embodiments of the present invention are not limited thereto.

A general purpose injection molding machine consisting essentially of four parts: the injection part, the mold closing part, the servo motor power system and the computer panel control system.

The electric injection molding machine is an injection molding machine which drives each mechanism by using an alternating current servo motor and matching with components such as a ball screw, a toothed belt wheel and the like, and is fundamentally characterized in that all driving modules are electric. The fully electric injection molding machine is the main type of the electric injection molding machine, and all mechanisms (injection, plasticization, metering, seat moving and the like) in the injection molding device and all mechanisms (mold opening and closing, mold locking, ejection and the like) of the mold closing device are driven by motors.

The main function of the injection drive is to plasticize the plastic into a molten state and to inject a certain amount of melt into the mold cavity with sufficient pressure and velocity. Thus, the injection device should have good plasticizing, metering accuracy, and provide pressure and velocity to the molten material during injection. The injection device generally consists of a plasticizing part (a melt rubber cylinder, a screw, a nozzle, etc.), a hopper, a metering device, a screw driving device, injection and the like.

The injection drive mechanism advances and retreats the screw. The roller lead screw is driven by the rotation of the AC servo motor and the action of the synchronous belt, and is converted into linear motion by the roller lead screw, so that the screw moves forwards or backwards. It is a mechanism for filling plasticized resin from a nozzle into a mold.

The screw rod melting mechanism enables the screw rod to rotate through the rotation of the AC servo motor and the action of the synchronous belt, and metering is carried out. The resin in the barrel is heated by the friction between the resins as the screw rotates, and the solid resin is melted by the heat transfer of the barrel heater to be in an injectable state.

The mold locking mechanism ensures that the molding mold is reliably closed, realizes the opening and closing actions of the mold, and ejects a product, namely a working part of the molded product. Since the melt entering the mold cavity also has a certain pressure during injection, it is required that the mold clamping device give the mold a sufficient clamping force to prevent the mold from being opened under the pressure of the melt, thereby causing flash or deterioration of the product accuracy. The mold closing device mainly comprises a template, a pull rod (a tie bar), a mold closing mechanism (such as a machine hinge), a product ejection device, a safety door, a mold adjusting device and the like.

The ball screw is driven by the rotation of the AC servo motor and the action of the synchronous belt pulley, so that the mold is opened or closed. The movement of the injection seat in the injection seat actuating mechanism is controlled by a gear motor, and the contact force of the mold is obtained by detecting the stress of a spring. The ejection mechanism drives the ball guide screw through the rotation of the AC servo motor and the action of the synchronous belt, so that the ejection plate moves forwards or backwards to complete the ejection process of the molded product. The mold thickness adjusting mechanism precisely maintains the parallelism of the grinding disks and the balance of the mold clamping force by the rotation of the gear motor.

The injection moulding machine is a continuous production process formed from the processes of melting plastics, closing mould, injection moulding, pressure holding, solidifying product and demoulding and taking out product, and the motor and electric power are power and control systems which are set up for ensuring that the injection moulding machine can accurately implement work according to the requirements (pressure, speed, temp., time and position) and action program predefined by technological process.

The control system controls the sequence of the injection molding cycle and maintains the process temperature, time, pressure and speed at set values (process control). The electric part mainly comprises power, action programs, heating and other controls.

As shown in FIG. 1, the motor injection molding machine mechanism of the utility model comprises A, B two parts:

part A: comprises three parts of glue melting, glue injection and sliding table displacement adjustment. When the glue melting servo motor 4 rotates, the toothed belt drives the end face of the screw rod 6 to push the glue melting screw rod to move leftwards, the glue melting screw rod acts on a flange plate of the pressure sensor 13, according to the preset glue melting back pressure P back, when P is larger than P back, the glue injection servo motor 14 rotates, the toothed belt wheel drives the ball screw to rotate (the screw is axially fixed), so that the movable support plate 3 moves leftwards, and the balance is achieved, and the glue melting back pressure P back is stabilized at a set value. During the glue melting process, the glue melting servo motor 4 moves at a rotating speed at a set glue melting speed. The glue injection servo motor 14 tracks the P back change of the pressure sensor to increase or decrease, so that the output analog signal is converted into a digital pulse signal and is transmitted to the glue injection servo motor 14 to rotate to stabilize the P back. The glue melting is controlled in the whole glue melting process due to the process requirement. The rotating speed of the screw can be divided into N levels, the switching position can be divided into N-1 levels, and the back pressure can be divided into X-1 levels [ in the glue melting process, the high-pressure mould locking forming, cooling, mould opening, ejection and part taking, rapid mould closing and high-pressure mould locking are carried out after glue injection ], the high-pressure mould locking is finished after glue melting, glue injection is carried out, the control is constant speed and constant pressure, the X-level speed and 1-level pressure control, the X-level pressure maintaining N-level pressure control is switched, and the time is set to be N-1 levels ].

The glue injection working process comprises the following steps: the glue injection servo motor 14 starts the two ball screws 1 to rotate, and the movable support plate 3 is driven to push the screw rod 6 to advance. The pressure sensor 13 bears pressure, and then the injection values of the injection pressures are compared. When the P is greater than or less than the predetermined value, the glue injection servo motor 14 tracks and rotates to reach stable P injection.

And part B: and opening and closing the die and ejecting the plastic part. The action principle is that a servo motor 11 drives a ball screw 9 through a toothed belt, a nut 21 moves forwards and linearly to push a crank arm cross to straighten, a crank arm pushes a movable template to lock the mold, the crank arm needs to be ensured to straighten after the mold locking is completed, a straightening detection point 19 is determined by a manufacturer when the mold is delivered, and the mold adjusting motor Y22 and the mold adjusting nut 23 can be used for changing according to the difference of the total thickness B of the mold. The pressure of the locking force Plock is controlled by the servo motor 11 by torque, the direct pressure (ton) of the locking force is converted into motor torque, and the motor torque can be controlled by current. I.e. pressure and current are linear, the detection current controls the motor to stop.

The ejection molding part servo motor 8 is started after the mold is opened, and can set X-level ejection and vibration ejection (N is more than or equal to 1).

In conclusion, the full-motor injection molding can control 4 shafts, and the same control of 4 shafts or the same control of2 shafts (4 and 14) achieves high-efficiency injection molding.

The utility model discloses as shown in fig. 2 the utility model discloses electric injection molding machine injection moulding process flow, electric injection molding machine's process flow is by six motor drive accomplishes the function of moulding plastics, and these six motors drive the open and shut mould control, melten gel control, penetrate gluey control, pressurize control, ejection control, penetrate a mobile control of injection molding machine respectively to and transfer the mould control. Some of the actions can be coincident actions, such as opening the mold and ejecting the mold, locking the mold and moving the injection table, etc. All actions are completed by the cooperation of the computer controller of the injection molding machine.

The action program of the injection molding machine: advancing the nozzle → injecting → maintaining pressure → premolding → inverting → retreating the nozzle → cooling → opening the mold → ejecting → withdrawing the needle → opening the door → closing the mold → advancing the nozzle.

1. And (3) operation items of the injection molding machine: the operation of the injection molding machine is controlled by a panel control keyboard, and an electric appliance control cabinet, a servo motor system and a mechanical lubricating device are checked. The injection process action, the feeding action, the injection pressure, the injection speed and the ejection type are selected respectively, the temperature, the current and the voltage of each section of the charging barrel are monitored, the injection pressure and the backpressure are adjusted, and the like.

2. Selecting injection process action: the general injection molding machine can be operated manually, and can also be operated semi-automatically and fully automatically. The manual operation is realized in a production cycle, and each action is realized by an operator pushing an operation switch. Generally, the method is selected when a test machine is used for adjusting the mold. The semi-automatic operation machine can automatically complete the action of one working cycle, but after each production cycle is finished, an operator must pull open the safety door, take down the workpiece and close the safety door, and the machine can continue the production of the next cycle. When in full-automatic operation, the injection molding machine can automatically enter the next working cycle after finishing the action of one working cycle. The control and adjustment are carried out without stopping the machine in the normal continuous working process. The operation of each injection molding machine can be roughly represented as a basic cycle program as shown in fig. 7:

(1) closing and tightening of moulds

The molding cycle of an injection molding machine generally begins when the mold begins to close. The mold is first closed at low pressure, and when the movable mold plate (the second mold plate) is close to the fixed mold plate (the head mold plate), the power system for closing the mold should be switched to low pressure and when no foreign matter exists in the mold cavity, the mold is switched to high pressure to close the mold.

(2) Advancing and injecting an injection device

After confirming that the mold has reached the required clamping force, the injection device is moved forward to attach the nozzle to the mold, and after the nozzle is attached to the mold, the injection motor is started, so that the screw connected to the motor injects the produced molten material into the mold cavity at high pressure and high speed. The injection pressure of the screw head on the melt is also referred to as the injection pressure.

(3) Pressure maintenance (pressure maintaining)

The molten material injected into the mold cavity is cooled to shrink due to the cooling effect of the low-temperature mold, and the molten material needs to be subjected to feeding while maintaining a certain pressure in order to obtain a product with compact quality. The pressure exerted by the screw on the melt is referred to as the hold pressure, during which the screw moves forward a small amount.

(4) Cooling and preplasticizing articles

When the pressure maintaining is carried out until the melt of the mold cavity loses the possibility of gate backflow (namely, the gate is closed), the pressure maintaining pressure of the injection motor can be removed (at the moment, the high pressure of the mold closing motor can also be removed), so that the product is cooled and shaped in the mold. At this time, the screw is rotated by the motor to forward and plasticize the granular or powdery compound from the hopper. The screw rod retreats while rotating under the action of the melt pressure at the head of the screw rod. The backward movement of the screw during plasticization represents the amount of melt accumulated in the head of the screw. When the screw is retracted to the metered value, the screw stops rotating and is ready for the next injection. The product cooling and screw plasticization are generally overlapped in time, and the metering time for screw plasticization is generally required to be less than the product cooling time.

(5) Injection device retreating and mold opening ejection product

After the screw is plasticized and metered, in order to prevent the nozzle from forming cold materials due to long-time contact with a cold die, and the like, the nozzle is frequently required to be withdrawn from the die, namely the injection device is withdrawn, and whether the action is carried out or not or the sequence of the action is carried out, and the machine can be selected. After the molten material in the die cavity is cooled and shaped, the die closing device is used for forming the space die, and the product is automatically ejected out.

(6) Operation of the machine

(ii) Manual State

And manually debugging whether each action of the injection molding machine meets the injection molding requirement. According to the requirement of the injection molding action circulation process, actions such as manual die opening and closing, injection table advancing, glue melting, injection, ejection and the like are independently completed.

② semi-automatic state

After various manual operations are normal, the debugging can be carried out in a semi-automatic state, and the knob latch and the knob switch which are required to be turned ON and OFF are turned ON to prevent the manual operation from being carried back. The knob is stopped at the semi-automatic position and the safety door is closed, the mold locking action is carried out and the circular work is carried out according to the set parameters. This operating state is suitable for trial injection products and some products that cannot be processed with full automation. When the safety door is closed and the LS-16 mold locking operation is carried out, the safety door can be opened after the mold locking operation is finished, and the whole cycle is stopped until the ejector pin operation is stopped.

③ full automatic state

When the manual and semi-automatic debugging is normal, the button is dialed to full-automatic. And closing the safety door, and then starting the full-automatic operation.

7. Temperature control

The temperature thermocouple is used as a temperature measuring element, and a millivolt temperature measuring meter is matched to form a temperature control device, so that the on-off of the current of the charging barrel and the current of the electric heating ring of the die are commanded, and the temperature of each section of the charging barrel and the temperature of the die are selectively fixed.

Fig. 3 shows a block diagram of the control system of the present invention, which includes a computer controller, a mold opening and closing (mold locking) servo motor and a DSP servo driver 1 for controlling the mold opening and closing mechanism of the injection molding machine; a glue injection servo motor and a DSP servo driver 2; the melt glue pressure maintaining servo motor and the DSP servo driver 3 respectively control a machine barrel of the injection molding machine to enable the screw to fill plastics into the injection mold; and the ejection servo motor and the DSP servo driver 4 control the ejection mechanism of the injection molding machine. The injection machine injection platform mechanism is used for aligning the injection machine injection platform with a mold runner port, and the injection platform moving motor is used for controlling the injection platform mechanism to move to a mold cavity port by the variable frequency controller 1. The mold adjusting mechanism is characterized in that a mold adjusting variable frequency controller 2 controls a mold adjusting motor to enable a mold to be closed to generate mold locking force.

In the specific implementation process, the utility model discloses a as shown in fig. 4 electronic injection molding machine control system structure, including interconnect's injection molding machine computer control ware, LCD display module, keyboard module, USB interface and net gape, CAN communication interface, 485 communication interface, four TMS32OF28335 servo driver, melten gel servo motor, penetrate gluey servo motor, mode locking servo motor, ejecting servo motor, transfer mould inverter motor controller, penetrate a platform inverter motor controller and PLC controller. The total number of the six motors for realizing the injection molding function is six. Wherein, 4 AC permanent magnet synchronous motors are adopted for controlling die assembling, sol dissolving, pressure maintaining, glue injecting and ejecting, and 2 common variable frequency motors are adopted for controlling moving and die adjusting of the injection platform. Exchange PMSM respectively by the utility model discloses a DSP servo controller control, ordinary inverter motor adopts two inverter controller controls. And the upper controller and the lower servo control system realize communication by adopting a high-speed CAN bus.

The upper computer adopts a main control chip of AMD GeodeTM LX800, and an embedded WINDOWS CE6.0 version is used as an operating system to construct a whole upper computer system. And a 10-inch LCD display screen, a keyboard input module, a PLC communication interface, a servo driver communication interface and the like are configured, and a USB interface and an Ethernet interface are reserved. The servo drive controller adopts TMS320F28335 of TI company as a core chip to drive a glue melting motor, a glue injection motor, a mode locking motor and an ejection motor of the injection molding machine, and the chip integrates various advanced peripherals and provides a good platform for the application of double motors. Therefore, the system adopts two controllers to realize the simultaneous control of four motors. The driver realizes the torque, speed and position control of the motor through related algorithms in the DSP by acquiring three-phase current and the speed of the motor rotor. The main circuit of the servo system adopts a typical voltage source type alternating current-direct current-alternating current frequency circuit, and the main power circuit consists of a rectifying circuit, a filter circuit and an inverter circuit. . Meanwhile, a frequency converter is used as a controller of the injection platform motor and the mold adjusting motor, and the PLC is responsible for all input and output quantities of the whole injection molding machine.

The closed-loop control requirements of a servo driver of the electric injection molding machine are as follows:

penetrate gluey servo motor: speed closed-loop control, torque closed-loop control (matched with a pressure sensor), angle (position) closed-loop control and locked rotor torque output control;

melt adhesive servo motor: speed closed-loop control;

mode locking servo motor: closed-loop control of speed, closed-loop control of angle (position) and closed-loop control of torque in a specified angle;

ejecting a servo motor: speed closed-loop control and angle (position) closed-loop control.

Servo drive controller interface functions: the system comprises a motor brake monitoring function, 2 analog quantity inputs (with isolation), a coded disc digital signal output (with isolation), 4 marking signal interfaces (with isolation), position, speed, torque control, a synchronization function, response speed, feedback time 62.5ms, a CAN interface (with isolation) or a TCP/IP bus interface.

Except that four main servo motors are controlled by a DSP, a mold adjusting motor and a platform shooting motor are controlled by a PLC. Meanwhile, the input and the output of the whole system are all taken charge of by the PLC. The system comprises 14 paths of analog quantity input, 8 paths of PWM output, 53 paths of switching value input of an injection molding machine and 60 paths of switching value output of the injection molding machine. The utility model discloses well PLC control action program table of moulding plastics is shown as table 1, wherein: the input switching values are states at the end of each operation.

TABLE 1

The switch input terminal (32-point input) of the injection molding machine is shown in table 2:

table 2:

the switch output terminals (1-32 point transistor output, 33-48 point relay output) of the injection molding machine are shown in table 3:

TABLE 3

The injection molding machine model quantity input/output terminals are shown in table 4:

table 4:

the connection between the upper control system and the lower servo control system is mainly completed by CAN communication, and the CAN communication has the main functions of: when a certain action is executed, the upper controller sends an instruction to the corresponding motor controller through the CAN bus, and after receiving the instruction, the controller executes the action according to the instruction requirement and sends back data (such as current magnitude) required to be counted in the execution process.

Different from the traditional hydraulic injection molding machine, the actions of the full-electric precise injection molding machine are respectively controlled by the motor, so that the synchronous action can be realized. This independent control mode is represented by software design, and the traditional sequential action control is separated into a plurality of independently controlled tasks, including: the method comprises eight independent tasks of mold opening, mold closing, glue melting, glue injection, pressure maintaining, ejection, forward movement of an injection table, backward movement of the injection table and the like. As shown in fig. 6, the core task of the computer control system is developed by embedding a real-time operating system Windows CE in a software architecture, the system is divided into a plurality of individual tasks, and the whole program framework is set as a real-time multi-task interrupt scheduling mechanism on the real-time system, including a glue injection device control (a backpressure sensor, a code disc), a glue melting (a backpressure sensor, a code disc), a mold opening (a lead screw stroke, a safety door opening and closing), a mold closing (a safety door closing, a code disc mold locking mechanism), a thimble motor transmission mechanism (an opening, a mold closing and a safety door closing), a shooting platform movement control (2 shooting platform limit switches, a shooting platform displacement electronic ruler), a mold adjusting structure (a front limit switch and a back limit switch, an automatic mold adjusting control, a manual mold adjusting), a temperature control (a screw, a charging barrel and a mold), a lubricating oil motor timing (an opening, a mold closing and an injection, The method comprises the steps of online self-learning control establishment of product quality, SPC control of precision injection molding products, injection pressure, position, time control curve and CAN bus network. The system specifically comprises the following modules:

(1) emergency key control module task: SecuPrt _ Task priority: 9

(2) The control module task of the glue injection motor is as follows: MotoJet _ Task priority: 10

(3) The sol motor control module tasks are as follows: motofuise _ Task priority: 11

(4) The motor control module tasks of opening and closing the die are as follows: mouldtrl _ Task priority: 12

(5) And (3) ejecting a motor control module: MotoPop _ Task priority: 13

(6) And (3) controlling tasks of a mobile motor of the injection platform: MotoMoveTask priority: 14

(7) The module adjusting motor control module tasks: MouldAdj _ Task priority: 15

(8) The temperature control module has the tasks: TempCtrl _ Task priority: 16

(9) And the communication control module tasks are as follows: comm _ Task priority: 17

(10) And (3) keyboard input module tasks: KeyBoard _ Task priority: 18

(11) The window display controls a certain task: UI _ Task priority: 19

(12) Communication port interrupt service routine: comm _ ISP

(13) Clock interrupt service routine: time _ ISP

(14) Keyboard interrupt service routine: KeyBoard _ ISP

(15) Emergency key interruption interrupt service routine: WarnKey _ ISP

According to the flow set in fig. 2, the following control method is adopted to control the four servo motors:

step one, selecting a working mode of a servo motor of the full-electric injection molding machine: manual, semi-automatic or fully automatic;

secondly, starting a control method of the servo motor control system according to a selected mode, wherein the manual mode is that parameters are manually input to independently control the actions of opening and closing the mold, advancing the injection platform, melting glue, injecting and ejecting according to the cyclic process requirement of the injection molding action; the semi-automatic working mode means that a servo motor control system completes single cycle action according to a control method according to the technological requirements of injection molding action; the full-automatic working mode is that the servo motor control system completes multiple circulating actions according to the process requirement of single circulating action according to the injection molding action process.

The second step of completing the single cycle action according to the control method comprises the following steps:

step I, closing the safety door;

step II, controlling a glue injection servo motor, and simultaneously controlling die assembly of an opening and closing servo motor;

step III, performing pressure maintaining control on the glue melting pressure maintaining servo motor;

step IV, performing melt glue control on a melt glue pressure maintaining servo motor, and performing die opening control on an opening and closing die servo motor and ejection control on an ejection servo motor at the same time;

and V, opening the safety door, and finishing.

As shown in fig. 9, the injection servo motor, the melt pressure maintaining motor and the controller are specifically connected, and controlling the injection servo motor and controlling the melt pressure maintaining servo motor means:

the glue injection process comprises the following steps: the glue injection motor does not work, the glue injection motor is started to drive the glue injection nut to rotate, the positions of the glue injection motor and the glue injection nut are not moved, the glue injection nut drives the ball screw to advance, meanwhile, the ball screw pushes the screw, the glue injection nut and the glue injection motor to advance, and the glue injection motor is stopped until the glue injection process is finished;

the glue melting process comprises the following steps:

the ith step: the glue melting motor is started, the glue melting motor drives the glue melting nut to rotate, the glue melting nut drives the screw to rotate, and a bearing is arranged at the joint of the screw and the ball screw, so that the screw can rotate freely without driving the ball screw to rotate;

step ii: the screw rod pushes the material forwards and heats the material to melt the material at the same time through rotation, the material is continuously conveyed to the head of the screw rod, the molten material gathered in the material storage area of the machine barrel generates certain pressure, the pressure is increased, the screw rod is pushed, but the pressure between the screw rod and the ball screw rod is increased because the ball screw rod tightly pushes the screw rod, and at the moment, a pressure sensor positioned at the connection part of the screw rod and the ball screw rod transmits a pressure measurement value to the DSP controller;

step iii: the DSP controller is compared with a pressure set value;

step iv: when the measured value of the pressure sensor exceeds a set value, the DSP controller controls the glue injection motor and the glue injection nut to start to rotate reversely, the positions of the glue injection motor and the glue injection nut do not move, the ball screw moves backwards according to a set speed, the screw rod also moves backwards, the glue melting nut and the glue melting motor drive the screw rod and simultaneously move backwards, and the ball screw keeps a certain pressure on the screw rod;

the v step: stopping the glue injection motor and the glue melting motor until the set retreating displacement is met, and finishing the injection amount and the reset of the ball screw, so as to prepare for next glue injection;

in the glue melting process: the equation of the motion function of the screw rod retreating is as follows:m: the total weight of the screw, the glue melting nut and the glue melting motor; g: acceleration of gravity; v: the screw retreating speed; f_a: pressure generated by melting the material; f_B: resistance of the ball screw; f_L: reaction force of the molten material; f: friction force.

The current relationship between the glue melting pressure maintaining motor and the glue injection motor is as follows:

the current loop open loop transfer function is:

K_vvoltage amplification factor, K, of an inverter of an external PWM unit_mAs a current feedback factor, T_vIs the inverter time constant, T_v＝1/f_v，f_vThe inverter has working frequency, s is differential, two motor armature loops are composed of a resistor R and an inductor L and are a first-order inertia link, T_oiThe filter time constant is sampled for the current,

wherein, T_oiAnd T_vAre all small time constants, equivalently one time constant T_ov＝T_oi+T_vAnd is also T_LL/R is the motor armature loop time constant, and the equation (1) is equivalent to:

the PI regulator of the motor corrects the current into an I-type system with better dynamic performance, and the transfer function of the regulator is

K_p，τ_cProportional coefficient and integral time constant of the PI regulator,

eliminating the pole of large time constant of the controlled object by the zero point of the current loop PI regulator, and taking tau_c＝L/R＝T_LTherefore, the open loop transfer function of the current loop corrected by the PI regulator is

(2) The formula reduces to a typical type I system:

wherein K is K_pK_v/(Rτ_c)；

The current loop closed loop transfer function is then:

$C\left(s\right)=\frac{G\left(s\right)}{1+G\left(s\right)}$

<math><mrow><mo>=</mo><mfrac><mrow><msub><mi>K</mi><mi>v</mi></msub><msub><mi>K</mi><mi>p</mi></msub><msub><mi>K</mi><mi>m</mi></msub></mrow><mrow><msub><mi>&tau;</mi><mi>c</mi></msub><mi>s</mi><mrow><mo>(</mo><msub><mi>T</mi><mi>ov</mi></msub><mi>s</mi><mo>+</mo><mn>1</mn><mo>)</mo></mrow><mo>+</mo><msub><mi>K</mi><mi>v</mi></msub><msub><mi>K</mi><mi>p</mi></msub><msub><mi>K</mi><mi>m</mi></msub></mrow></mfrac></mrow></math>

$=\frac{K}{s(T_{\mathrm{ov}}s+1)+K}$

<math><mrow><mo>=</mo><mfrac><msup><msub><mi>&omega;</mi><mi>n</mi></msub><mn>2</mn></msup><mrow><msup><mi>s</mi><mn>2</mn></msup><mo>+</mo><mn>2</mn><mi>&xi;</mi><msub><mi>&omega;</mi><mi>n</mi></msub><mi>s</mi><mo>+</mo><msup><msub><mi>&omega;</mi><mi>n</mi></msub><mn>2</mn></msup></mrow></mfrac></mrow></math>

ω n is cut-off frequency, and damping ratio ξ is 0.707 according to the optimal performance index of the second-order system, namely

To find K, τ_c＝L/R＝T_LDetermining K_p，τ_c；

The current loop is the inner loop of the velocity loop and, given the transfer function of the current loop,

velocity loop closed loop transfer function:

beta is the voltage vector, K_fnFor the velocity feedback coefficient, T_mIs the electromechanical time constant of the motor, K_ΦAs a result of the potential coefficient of the motor,

T_onfor the rotational speed feedback filtering time constant,

T_land T_onAre all small time constants, equivalently one time constant T_fs＝T_l+T_onThe inertia link of (2), the speed loop control object is:

<math><mrow><msub><mi>C</mi><mi>i</mi></msub><mrow><mo>(</mo><mi>s</mi><mo>)</mo></mrow><mo>=</mo><mfrac><mrow><msub><mi>K</mi><mi>l</mi></msub><mi>R</mi><msub><mi>K</mi><mi>fn</mi></msub></mrow><mrow><msub><mi>T</mi><mi>m</mi></msub><msub><mi>K</mi><mi>&Phi;</mi></msub><mi>s</mi><mrow><mo>(</mo><msub><mi>T</mi><mi>fs</mi></msub><mi>s</mi><mo>+</mo><mn>1</mn><mo>)</mo></mrow></mrow></mfrac><mo>=</mo><mfrac><mrow><msub><mi>K</mi><mi>l</mi></msub><mi>R</mi><msub><mi>K</mi><mi>fn</mi></msub><mo>/</mo><msub><mi>T</mi><mi>m</mi></msub><msub><mi>K</mi><mi>&Phi;</mi></msub></mrow><mrow><mi>s</mi><mrow><mo>(</mo><msub><mi>T</mi><mi>fs</mi></msub><mi>s</mi><mo>+</mo><mn>1</mn><mo>)</mo></mrow></mrow></mfrac><mo>=</mo><mfrac><msub><mi>K</mi><mi>on</mi></msub><mrow><mi>s</mi><mrow><mo>(</mo><msub><mi>T</mi><mi>fs</mi></msub><mi>s</mi><mo>+</mo><mn>1</mn><mo>)</mo></mrow></mrow></mfrac></mrow></math>

the speed loop is corrected to a typical type II system, the speed loop regulator is a PI regulator, and the transfer function is

The open-loop transfer function of the speed loop after being regulated by the PI regulator is as follows:

<math><mrow><msub><mi>C</mi><mi>s</mi></msub><mrow><mo>(</mo><mi>s</mi><mo>)</mo></mrow><mo>=</mo><mfrac><mrow><msub><mi>K</mi><mi>ps</mi></msub><mrow><mo>(</mo><msub><mi>&tau;</mi><mi>s</mi></msub><mi>s</mi><mo>+</mo><mn>1</mn><mo>)</mo></mrow><msub><mi>K</mi><mi>c</mi></msub></mrow><mrow><msub><mi>&tau;</mi><mi>s</mi></msub><mi>J</mi><msup><mi>s</mi><mn>2</mn></msup><mrow><mo>(</mo><mn>2</mn><msub><mi>T</mi><mi>fs</mi></msub><mi>s</mi><mo>+</mo><mn>1</mn><mo>)</mo></mrow><mo>,</mo></mrow></mfrac></mrow></math>

kc is a proportionality coefficient which is a constant value, J is the rotor inertia of the motor which is a constant value,

after the correction of the PI regulator, the speed loop is a typical II type system, and the open loop transfer function of the speed loop is as follows:

wherein, K_N＝K_onK_ps/τ_sDefining the width of the intermediate frequency band h ═ tau in the open-loop amplitude-frequency characteristic for the open-loop amplification factor of the speed loop_s/T_fsThe dynamic performance index of a typical II type system is determined, h is increased, the overshoot is reduced, but the change of the adjusting time along with h is not monotonous, when h is 5, the adjusting time is shortest, the dynamic response is fastest, and a proper cut-off frequency omega is selected_nCalculating to obtain tau_sAnd K_ps：

<math><mfenced open='{' close=''><mtable><mtr><mtd><msub><mi>&tau;</mi><mi>s</mi></msub><mo>=</mo><mi>h</mi><mo>*</mo><msub><mi>T</mi><mi>fs</mi></msub></mtd></mtr><mtr><mtd><msub><mi>K</mi><mi>ps</mi></msub><mo>=</mo><mfrac><mrow><mi>h</mi><mo>+</mo><mn>1</mn></mrow><mrow><mn>2</mn><mi>h</mi></mrow></mfrac><mo>*</mo><mfrac><mrow><msub><mi>T</mi><mi>m</mi></msub><msub><mi>K</mi><mi>&Phi;</mi></msub></mrow><mrow><msub><mi>T</mi><mi>fs</mi></msub><msub><mi>K</mi><mi>l</mi></msub><mi>R</mi><msub><mi>K</mi><mi>fn</mi></msub></mrow></mfrac></mtd></mtr></mtable></mfenced></math>

The time period and the gain of the speed loop are tau_WAnd K_WThe position control loop adopts a proportional regulator, and the value of the proportional regulator is set to K_θThe closed loop transfer function of the position loop is:

<math><mrow><msub><mi>G</mi><mi>p</mi></msub><mrow><mo>(</mo><mi>s</mi><mo>)</mo></mrow><mo>=</mo><mfrac><mi>&theta;</mi><msup><mi>&theta;</mi><mo>*</mo></msup></mfrac><mo>=</mo><mfrac><mrow><msub><mi>K</mi><mi>&theta;</mi></msub><msub><mi>K</mi><mi>W</mi></msub><mo>/</mo><msub><mi>&tau;</mi><mi>W</mi></msub></mrow><mrow><msup><mi>s</mi><mn>2</mn></msup><mo>+</mo><mi>s</mi><mo>/</mo><msub><mi>&tau;</mi><mi>W</mi></msub><mo>+</mo><msub><mi>K</mi><mi>&theta;</mi></msub><msub><mi>K</mi><mi>W</mi></msub><mo>/</mo><msub><mi>&tau;</mi><mi>W</mi></msub></mrow></mfrac><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>3</mn><mo>)</mo></mrow></mrow></math>

theta is position feedback, theta^*For a given position, the position loop gain is set to K_p＝K_θK_WThen, the formula (3) is:

wherein, <math><mrow><mi>&xi;</mi><mo>=</mo><mfrac><mn>1</mn><mn>2</mn></mfrac><msqrt><mfrac><mn>1</mn><mrow><msub><mi>K</mi><mi>p</mi></msub><msub><mi>&tau;</mi><mi>W</mi></msub></mrow></mfrac></msqrt><mo>,</mo></mrow></math> <math><mrow><msub><mi>&omega;</mi><mi>n</mi></msub><mo>=</mo><msqrt><mfrac><msub><mi>K</mi><mi>p</mi></msub><msub><mi>&tau;</mi><mi>W</mi></msub></mfrac></msqrt></mrow></math>

the position servo system is in a critical damping state or an under-damping state, and the cut-off frequency f of a velocity link is corrected_W＝1/τ_WAfter determination, the following steps are determined by ξ ≧ 1: k_p≤1/(4τ_W)，K_p＝1/(4τ_W) The loop gain is controlled for the optimal position.

A specific connecting line diagram of the die opening and closing motor, the ejection motor and the controller is shown in fig. 9, and the step of controlling the ejection motor of the die opening and closing motor comprises the following steps:

step 1, determining a ball screw, a die opening and closing motor and an ejection motor which are selected by a die closing device and an ejection device according to the die moving speed characteristic and the force increasing characteristic of the die opening and closing process of the double-toggle mechanism by adopting a five-hinge die closing double-toggle mechanism and a crank slide block ejection mechanism;

and step 2, controlling the die opening and closing motor and the ejection motor and setting perfect die protection measures according to the load characteristics and the process requirements of the die opening and closing motor and the ejection motor, wherein the steps comprise:

(1) in the mold closing process, firstly, the mold closing is quickly carried out at low pressure, when the movable mold plate is close to the fixed mold plate, the mold closing is automatically switched to the low-speed mold closing, and after the fact that no foreign matter exists in the mold cavity is determined, the mold is switched to the high pressure again to close the mold; in the mold closing process, in order to prevent the overflow of mold materials, a large mold closing force needs to be applied, and a mold opening and closing motor is controlled by torque in the process;

(2) in the mold opening process, firstly, the mold cavity surface of the injection part cooling mold is ensured to be separated from the position of the guide pillar, then the movable mold plate moves at a constant speed to open the mold quickly, and the movable mold plate stops at a slow speed when approaching the starting position of the movable mold plate;

(3) the ejection speed is adjusted by adjusting the rotating speed of the ejection motor, so that the in-mold product is accurately and stably ejected;

the ball screw, the die opening and closing motor and the ejection motor which are selected by the die closing device and the ejection device are determined in the step 1: firstly, determining the shaft diameter, the lead, the length of a lead screw, the shaft diameter and the precision grade of the lead screw according to the translation working condition of a five-hinge die-closing double-crank die-closing mechanism; and selecting a mold opening and closing motor and an ejection motor by comprehensively considering the required mold locking force, the mold moving speed, the stroke ratio, the ball screw lead and the transmission ratio of the belt transmission device.

Determining whether a foreign object is in the fixed die cavity in the step 2 (1) means that a detection interval is set at a position close to the fixed die plate, and whether an obstacle exists or not is determined by detecting whether the change of the load current of the die opening and closing motor exceeds the limit;

the step 2 (2) of ensuring that the cavity surface of the injection part cooling mold is separated from the guide post is set to be the position when the guide post is contacted with the mold on the fixed side;

the mold closing process in the step 2 and the step (1) comprises the following steps:

firstly, moving from a mold opening end position to a mold closing speed change position, namely a mold closing speed 1 stage;

moving from the mold closing speed changing position to the mold protecting position, wherein the mold closing speed is 2 sections, and the sections move at high speed and low pressure;

thirdly, moving from the mold protection position to the mold contact position, namely a mold closing speed 3 section, wherein the section is a mold protection area, if the current sensor monitors that the current of the section is increased compared with a common current curve during mold closing, the residual plastic on the end face of the mold is not taken out, the mold closing process is stopped, and the mold is immediately opened;

fourthly, moving the mold from the mold protection area to the mold for closing, and applying maximum pressure to mold locking;

as shown in fig. 8, the mold transfer speed of the 2 nd mold opening and closing process is obtained as follows:

firstly, moving template stroke

According to the structural analysis, the moving stroke S of the movable template_mThe displacement of the B point of the hinged support can be characterized as follows:

<math><mrow><msub><mi>S</mi><mi>m</mi></msub><mo>=</mo><msub><mi>L</mi><msub><mi>AB</mi><mn>0</mn></msub></msub><mi>cos</mi><msub><mi>&gamma;</mi><mn>0</mn></msub><mo>-</mo><msub><mi>L</mi><msub><mi>AB</mi><mn>1</mn></msub></msub><mi>cos</mi><msub><mi>&gamma;</mi><mn>1</mn></msub><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>4</mn><mo>)</mo></mrow></mrow></math>

in the formula (4)

Is the center line of hinge A, B in the final lock position.

$L_{{\mathrm{AB}}_O}={\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HSA00000220249300031.png"\; state="\{\{state\}\}">L</figure-callout>}}_1+L_2---\left(5\right)$

<math><mrow><msub><mi>L</mi><msub><mi>AB</mi><mn>1</mn></msub></msub><mo>=</mo><msub><mi>L</mi><mn>1</mn></msub><mi>cos</mi><msub><mi>&alpha;</mi><mn>1</mn></msub><mo>+</mo><msub><mi>L</mi><mn>2</mn></msub><mi>cos</mi><msub><mi>&beta;</mi><mn>1</mn></msub><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>6</mn><mo>)</mo></mrow></mrow></math>

Elbow length ratio λ L₁/L₂According to the sine law

Thus, can obtain <math><mrow><msub><mi>S</mi><mi>m</mi></msub><mo>=</mo><msub><mi>L</mi><mn>1</mn></msub><mrow><mo>(</mo><mn>1</mn><mo>-</mo><mi>cos</mi><msub><mi>&alpha;</mi><mn>1</mn></msub><mo>+</mo><mfrac><msqrt><mn>1</mn><mo>-</mo><msup><mi>&lambda;</mi><mn>2</mn></msup><msup><mi>sin</mi><mn>2</mn></msup><msub><mi>&alpha;</mi><mn>1</mn></msub></msqrt><mi>&lambda;</mi></mfrac><mo>)</mo></mrow><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>7</mn><mo>)</mo></mrow></mrow></math>

<math><mrow><msub><mi>&alpha;</mi><mn>1</mn></msub><mo>=</mo><msup><mi>cos</mi><mrow><mo>-</mo><mn>1</mn></mrow></msup><mo>[</mo><mn>1</mn><mo>-</mo><mfrac><mrow><msub><mi>S</mi><mi>m</mi></msub><mrow><mo>(</mo><mn>2</mn><msub><mi>L</mi><mn>1</mn></msub><mo>-</mo><msub><mi>S</mi><mi>m</mi></msub><mi>&lambda;</mi><mo>)</mo></mrow></mrow><mrow><mn>2</mn><msub><mi>L</mi><mn>1</mn></msub><mrow><mo>(</mo><msub><mi>L</mi><mn>1</mn></msub><mo>+</mo><mi>&lambda;</mi><msub><mi>L</mi><mn>1</mn></msub><mo>-</mo><mi>&lambda;</mi><msub><mi>S</mi><mi>m</mi></msub><mo>)</mo></mrow></mrow></mfrac><mo>]</mo><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>8</mn><mo>)</mo></mrow></mrow></math>

② stroke S of piston rod_gSum stroke ratio K_S

Piston rod stroke is a term followed for hydraulic clamping devices, in which a motor drives a clamping device S_gRepresents the travel of the crosshead, characterized by the amount of movement of the hinge E on the crosshead:

the ratio of the stroke of the die plate to the stroke of the crosshead is called the stroke ratio K_S＝S_M/S_g(12)

K_SThe ratio of the mold moving speed to the crosshead moving speed is reflected, and the energy consumption of the machine table is also reflected;

③ die-moving speed V_mAnd coefficient of variation of velocity K_V

The mold-moving speed of the toggle rod type mold-closing mechanism can be controlled, if the friction loss is neglected, the power input to the mold-closing mechanism is equal to the power output according to the energy conservation theorem, namely

P_B·V_B＝P_M·V_M (13)

So that the moving speed of the template can be obtained

By controlling as above, optimal control of the all-electric injection molding machine can be achieved.

The embodiments of the present invention are only preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be regarded as equivalent replacement modes, and all are included in the scope of the present invention.

Claims (4)

1. A servo motor control system of a full-electric injection molding machine is characterized by comprising an injection molding machine computer controller, a servo motor controller and a PLC (programmable logic controller); the computer controller is connected with the servo motor controller through a CAN bus, the servo motor controller is connected with the servo motor, and the computer controller is connected with the PLC; the servo motor controller is an opening and closing die servo motor controller, a glue injection servo motor controller, a glue melting and pressure maintaining servo motor controller and an ejection servo motor controller; the servo motors are an opening and closing die servo motor, a glue injection servo motor, a glue melting and pressure maintaining servo motor and an ejection servo motor.

2. The servo motor control system of the all-electric injection molding machine according to claim 1, further comprising an LCD display module, a keyboard module, an ethernet control chip respectively connected to the injection molding machine computer controller; the injection molding machine computer controller adopts an AMD microprocessor, and the servo motor controller adopts a DSP controller.

3. The servo motor control system of the fully electric injection molding machine according to claim 2, wherein in the glue-shooting servo motor controller and the glue-melting pressure-maintaining servo motor controller, the SCI module of the DSP controller is connected to the pressure sensor, the JTAG module of the DSP controller is connected to the control emulator LED lamp, the I/O module of the DSP controller is connected to the control alarm output positioning completion signal LED lamp, the 2 EVA/B modules of the DSP controller are connected to the external PWM unit, the external PWM unit is connected to the glue-shooting servo motor and the glue-melting pressure-maintaining servo motor through IPM power driver boards, the glue-shooting servo motor and the glue-melting pressure-maintaining motor respectively feed back current signals to the ADC module of the DSP controller through the current sensors, and the glue-shooting servo motor and the glue-melting pressure-maintaining servo motor respectively feed back signals to the QEP module of the DSP controller through code disks.

4. The servo motor control system of the fully electric injection molding machine according to claim 2, wherein in the mold opening and closing servo motor controller and the ejection servo motor controller, one output end of the DSP controller is connected to the injection molding machine computer controller and the emulator through its own CAN bus communication module and JTAG interface, respectively, and the other output end is connected to the IPM power driving board and the servo motor in sequence through its own event manager EVA/B, the servo motor is connected to the analog-to-digital conversion module ADC of the chip through a current sensor, and the servo motor is further connected to the quadrature encoder unit QEP of the chip through a code wheel; the servo motor refers to an opening and closing motor and an ejection motor.

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