CN1014964B - Injection molding machines and methods for controlling same - Google Patents
Injection molding machines and methods for controlling sameInfo
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- CN1014964B CN1014964B CN 90102761 CN90102761A CN1014964B CN 1014964 B CN1014964 B CN 1014964B CN 90102761 CN90102761 CN 90102761 CN 90102761 A CN90102761 A CN 90102761A CN 1014964 B CN1014964 B CN 1014964B
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Abstract
An injection molding machine generally comprises a heating cylinder, a screw which rotates and does reciprocating movement in the heating cylinder, and a screw drive system, wherein the screw drive system comprises two motors and two sensors which are respectively connected with the motors. A control system combines the rotation number and the back pressure of the screw, or independently and automatically controls the two motors in order to exactly finish a resin measurement working procedure. The control system properly controls a movement control system comprising the screw and a screw drive device according to the screw speed instructions of various control modes, screw rotation number feedback signals and screw position feedback signals.
Description
The present invention relates to a kind ofly measure in material resin that high accuracy control is configured in the injector of screw speed, position and back pressure in the injector cartridge heater in the operation, but also relate to a kind of method of controlling the injector of same purposes.
In design during injector, especially when the control of considering various steps or automation mechanized operation, must be noted that the improvement of product quality, the raising of energy-conservation and production efficiency, measure in the operation in material resin especially and especially will note these problems.Improve this point from product quality,, just need to measure the accurate amount that high accuracy is injected resin because its quality mainly is subjected to the influence of injection speed, pressure, resin temperature, injection rate etc.From energy-conservation this point; because the material resin with grain shape feeding injector cartridge heater is to heat in injector; by screw rod shearing with stir with the resin that obtains even fusion; therefore the energy of resin measuring process can be controlled screw rod effectively according to screw speed (below be called revolution) and back pressure, the temperature of resin of wanting fusion and kind and form and operates and reduce to minimum; and the production efficiency of moulded product can improve at interval by reducing measurement operation required time.
In general, in injector, material resin feeds cartridge heater by hopper, and the resin of feeding cartridge heater is by screw rod rotation feeding forward.In this operating process, resin is by heater, as is placed in the heater coil heating of cartridge heater excircle, then, by the rotational shear of screw rod, stirs.When the resin of feeding in the space that the cartridge heater fore-end forms injects mould by the nozzle that forms at the cartridge heater fore-end.The resin pressure that injects mould bounces back screw rod a little, prevents that thus the resin of fusion from outwards flowing out.At this moment, apply back pressure to screw rod, prevent from thus air to be introduced cartridge heater and accurately measured amount of resin from nozzle and hopper by the driving mechanism that connects screw rod effectively.Therefore, screw rod retracts gradually by resin pressure and the pressure reduction that added between the back pressure by transmission mechanism.The revolution of screw rod and back pressure are to give by rule of thumb calmly according to the type of used resin and temperature.Be used for determining that the screw rod of resin injection amount is by checkout gear in the position of cartridge heater, as limit switch, the device of (checkout gear is configured in the transmission mechanism) and lead-screw rotation and provide the device of back pressure to determine to screw rod.
Because the structure of above-mentioned universal injector, the position of screw rod are to be detected by limit switch, then indirectly by relativeness control between screw rod revolution and its back pressure.So just produce such problem: because after the limit switch action, screw rod stops the rotation, screw rod is parked in departs from the position of the position that requires, in prior art in order to overcome this shortcoming, can only reduce the rotation of screw rod at screw rod during near limit switch gradually, or after considering that screw rod moves excessively backward, before theoretical operating point, determine the operating point of limit switch.For the above reasons, necessary sound out repeatedly and revise in the resin measuring process determine the actual screws position.And, because external factor or interference, as: the kind of used resin, mold shape, variations in temperature, resin humidity with from the variation of the amount of resin of hopper feeding cartridge heater, the operating point of accurate definite limit switch is very complicated, like this, it is very difficult obtaining resin injection rate and limit switch operating point.Therefore, can not inject resin equably, also can not prevent the decline of molded product quality, and, in this common technology, even in course of normal operation, also unnecessarily reduce the screw rod revolution, make screw rod be parked in accurate position, could measure amount of resin at short notice and obtain higher energy efficiency and improvement productivity ratio.Because above-mentioned interference, measure the vibration of screw rod in the operation or toning at resin and measure operation at resin and apply unnecessarily compression or pressure to resin nocuously and reduce and cause that the resin of fusion flows out from nozzle, or flow into hopper on the contrary.Therefore, with regard to needs suitably according to the speed of screw rod and Position Control injector and even can change the characteristic that does not also influence screw rod in the operating process in the injector control system.
One object of the present invention just provides a kind of improved injector that can control its transmission mechanism, so as accurately to machine independent or measure operation with the revolution and the back pressure of screw device.
Another object of the present invention just provides a kind of by suitably controlling the kinetic control system that comprises screw rod and screw drive mechanism, accurately controls the method that above-mentioned form injector is measured operation.
According to the present invention, provide a kind of injector of form on the one hand, the material resin that infeeds the hollow cartridge heater in this injector is heated and is fed forward by screw rod.This screw rod makes its rotation by transmission mechanism and moves back and forth in cartridge heater.Fusion and plasticized resin are injected mould in cartridge heater, and the position and the revolution thereof of screw rod are detected by checkout gear.This injector is characterised in that transmission mechanism comprises first motor that makes the screw rod rotation and makes reciprocating second motor of screw rod.Its feature also is: checkout gear comprises: detect the screw rod revolution and send the first sensor that effectively is connected in first motor of screw rod revolution feedback signal and detect screw position and send second sensor that effectively is connected in second motor of screw position feedback signal.First and second motor are controlled by control system, the command signal of screw position, and the feedback signal of screw rod revolution and the feedback signal of screw position are imported this control system.Control system is sent the screw rod rotating signal and is sent the screw back pressure signal to second motor to first motor, and making position command signal and position feed back signal difference is zero substantially, and this control system can be revised and make it have various control modes.
On the other hand; according to the invention provides a kind of method of in resin measurement operation, controlling injector; wherein; the difference that screw speed is adjusted between input value and the screw speed output valve is input to the speed loop amplifier element; control comprises the kinetic control system of screw rod and screw drive mechanism, and screw speed instructs and the screw rod output valve is input to the suitable control element that connects with amplifier element.The feature of this method is: the output valve from amplifier element is added on the speed command, the screw speed output valve is promptly imported this amplifier element, adjust input value to obtain screw speed, and the value of magnification of amplifier element changes according to the control element output valve of mating.
Also has an aspect; according to the invention provides a kind of method of in resin measurement operation, controlling injector; comprising the speed control system that is equipped with the speed loop amplifier element; screw speed is adjusted the difference input speed control system between input value and the screw speed output valve; also be equipped with a controlled kinetic control system, comprise a screw rod and screw drive mechanism and amplifier element.This method feature also is: a kind of observing unit is provided, and this observing unit is just imported in the screw speed instruction.Observing unit has the characteristic same with speed control system, give and decide value of magnification and multiplied each other by a constant, make it equal difference between screw speed output valve and the observing unit output valve, and the difference of output valve after multiplying each other and screw speed instruction is adjusted output valve as screw speed.
As mentioned above, according to the present invention, resin in the cartridge heater can be at external factor or interference, as the signal of change control screw driven systems such as the temperature of the kind of used resin, mold shape, resin, humidity and accurately obtain measuring, finish and measure the required time and also can reduce, and the productivity ratio of high-quality moulded product can improve widely.
Characteristic of the present invention, principle and be applied in will be clearer after having read following detailed description with reference to accompanying drawing.
In the accompanying drawing:
Fig. 1 is the principle longitudinal section of common form injector;
Fig. 2 is the principle longitudinal section of injector of the present invention;
Fig. 3 is the block diagram of expression embodiment of injector control system according to the present invention;
Fig. 4 is the curve map of characteristic between injector screw rod revolution and the back pressure in the presentation graphs 3;
Fig. 5 is an injector longitudinal section of the present invention;
Fig. 6 is the curve map that shows an embodiment of position control component generation effect among Fig. 3;
Fig. 7 is the flow chart of expression position control component operation;
Fig. 8, Fig. 9 and Figure 11 are the curve maps of an example of presentation graphs 3 speed control element generation effects;
Figure 10 and Figure 12 are the flow charts of speed control element operation;
Figure 13 is the curve map of an example of back pressure control element generation effect in the presentation graphs 3;
Figure 14 is the flow chart of expression back pressure control element operation;
Figure 15 is the curve map of an example of presentation graphs 3 transfer numerical control system element generation effects;
Figure 16 is a revolution control element operational flowchart;
Figure 17 is the block diagram of another embodiment of expression control system of the present invention;
Figure 18 represents that embodiment is similar in appearance to the curve map of the characteristic of Figure 14 among Figure 17;
Figure 19 is the curve map of expression by an example of Figure 17 back pressure control element generation effect;
Figure 20 is a back pressure control element operational flowchart;
Figure 21 is the block diagram of another embodiment of control system of the present invention;
Figure 22 represents that embodiment is similar in appearance to the performance diagram of Fig. 4 or Figure 18 among Figure 21;
Figure 23 is the dynamic system model figure that explains control principle according to the present invention;
Figure 24 is that expression control system shown in Figure 3 is the block diagram of benchmark with speed;
Figure 25 is a block diagram of explaining an embodiment of control method of the present invention;
Figure 26 is used for the step response curve figure of control system feature measurement shown in Figure 25;
Figure 27 is the block diagram of control system when control method of the present invention is used in control system shown in Figure 3.
Figure 28 is a block diagram of explaining another embodiment of control method of the present invention.
In order to understand accurate characteristic of the present invention better, the ordinary circumstance of general injector and the variety of issue that the known type injector is run into are discussed with reference to Fig. 1.
Fig. 1 represents a universal class injector principle vertical section, wherein, material resin 4 is by hopper 3 feeding cartridge heaters 2, then by 1 rotation of screw rod in the cartridge heater 2 feeding forward, it is feeding left among Fig. 1, resin 4 in the cartridge heater 2 is by heater, as: be installed in the heater coil on cartridge heater 2 excircles; Heating and by screw rod shearing with stir with plasticizing resin.The molten resin 6 of Huo Deing is stored in the space that cartridge heater 2 fore-ends form like this, injects the die cavity of mould 30 then by cartridge heater 2 nozzle segments 5.In this course because the front end of nozzle 5 is facing to the opening pressurization of mould 30, as long as the resin of fusion fills up that die cavity just makes screw rod the pressure of molten resin backward, that is: the Y direction moves.In order to provide back pressure to enter cartridge heater 2 and accurately measure amount of resin in resin measurement operation to prevent the air in molten resin 6 outflows and nozzle 5 and the hopper 3 to screw rod 1, transmission mechanism 7 is connected with screw rod effectively.Like this, screw rod is because the pressure reduction between the back pressure that the rotation of screw rod and transmission mechanism produce is little by little mobile backward.In the above-mentioned type injector, the screw position of the amount of resin that decision will be injected is being considered used resinous type, and temperature etc. are back to be determined as the limit switch that is contained in the transmission mechanism 7 by checkout gear.
But, detect and determine that there are the above-mentioned variety of issue that accurately detects screw position in measuring operation in the system of measuring process screw position or mechanism by limit switch.Therefore, just need provide a kind of improved mechanism or device and method that addresses these problems.
Fig. 2 represents an injector functional-block diagram, and wherein the element of reference number indication is identical with element shown in Figure 1.Among Fig. 2, motor 21 by power transmission shaft effectively with cartridge heater 2 in screw rod 1 connect.Motor 21 is contained on the transmission platform 24, and this transmission platform 24 connects with the ball nut of ball screw rod 22 engagements, and ball screw rod 22 connects with motor 20 effectively by motor 20 power transmission shafts.
When motor turned round according to signal Ri, screw rod began rotation, and material resin is from hopper 3 feeding cartridge heaters 2.Resin is owing to plasticizing resin is thus sheared and stirred in the motion of screw rod then.When cartridge heater 2 was full of the resin 6 of plasticizing thus or fusion, screw rod 1 was promptly moved with the direction of N backward by the pressure of the molten resin of storing.In this course, back pressure just acts on and allows on the screw rod accurately measure amount of resin and can not suck cartridge heater 2 to air.In direction is when the back pressure of M heads on the power that makes screw retracts, be contained on the transmission platform 24 motor 21 backward with the N direction, therefore, produce moment of torsion by the ball nut 23 with 22 engagements of ball screw rod, ball screw rod 22 connects with the motor 20 that turns round according to the signal Pi that sends from control module 10.The sensor 25 that is connected in motor 21 detects the revolution n of screw rods 1 and sends with screw rod revolution feedback signal Rf to control module.The sensor 26 that is connected in motor 20 detects the position of ball nut 23, promptly; The position of screw rod 1, and send screw position signal Sf corresponding to back pressure P to control module 10.
Fig. 3 is the block diagram of control module 10.With reference to Fig. 3, the signal input of pressure reduction Se constitutes the position control component 11A of command value executive component 11 between position command signal Si that instruction generation device 70 sends and the screw position feedback signal Sf, the same speed control element 11B that constitutes executive component 11 of signal So input with the operation of compensation closed loop controller characteristic, the back pressure command signal Hi and the revolution command signal Ki of control screw rod 1 export from speed control element 11B, back pressure command signal Hi input back pressure control element 12, for the signal Ho of compensation closed loop controller characteristic operation from back pressure control element 12 input power amplifiers 13, electrical power is amplified by amplifier 13, and screw back pressure signal Pi input motor 20 is to control this motor 20.Simultaneously, revolution command signal Ki imports subtracter 14, difference forms the signal Ke of relevant pressure reduction between signal Ki and the revolution feedback signal Rf, should be from the signal input revolution control element 15 of subtracter 14, the output signal Ko input electric power amplifier 16 of compensation closed loop controller characteristic operation is to amplify electrical power, and screw rod rotating signal Ri is admitted to motor 21.
Fig. 4 represents to explain the characteristic curve of the injector operating process with said structure.Transverse axis is represented the revolution n of screw rod 1 in this curve, and the longitudinal axis is represented the back pressure P of screw rod 1, alphabetical V
0To V
4Represent the movement velocity (V of screw rod 1
0Low speed; V
4At a high speed).
2 explanation moulds or make-up machine 30 are measured the sequence of operations process of operation at resin with reference to the accompanying drawings.
Because the molten resin that will measure 6 amounts are that therefore, the position command signal Si of Input Control Element 10 just represents the amount of resin 6 according to the stop position decision of screw rod 1.When position sensor 26 sent screw position feedback signal Sf corresponding to position command signal Si, measuring process can be finished.The operation of finishing measuring process is illustrated with reference to Fig. 3.When difference Se input position control element 11A, pressure reduction Se is controlled to give fixed frequency characteristic compensation closed loop characteristic by it, produces the signal So of input speed control element 11b.The speed control element produces the back pressure instruction Hi and the revolution instruction Ki of control screw rod, and screw speed is reduced as zero and finish measuring process.This process is explained with reference to Fig. 4 curve, when the resin measuring process begins.Instruction Hi and Ki indication back pressure P and revolution n make screw rod 1 obtain high as far as possible revolution n
4Measure efficient to increase.In other words, the speed V of screw rod 1
4Be with the motion of N direction with relative mistake decision between the back pressure of M direction by screw rod 1 shown in Figure 2.Dotted line shows syntagmatic between revolution n and the back pressure P among Fig. 4, and revolution n and back pressure P change in measuring process, and oblique line L
1Can choose at random definitely, it is at screw rod revolution n that resin is measured operation
4With back pressure P
4Beginning becomes n subsequently
3P
3, n
2P
2, n
1P
1Revolution is ns when screw speed is Vo at last, and back pressure is Ps, and the screw rod stop motion is measured operation to finish resin then, and, at screw speed near V
0The time revolution ns and back pressure Ps be substantially zero, when measuring process was over, screw rod is parked in to give according to position command smoothly to be decided the tram and can not turn over this tram.Like this, with regard to the correct amount of resin that can obtain to measure, at this moment back pressure P then is chosen as a desired value Ps to prepare measuring process next time.In addition, at the revolution n that measures the selected high value of operation, the frictional heat between resin and the screw rod just can increase, and has promptly reduced the energy of cartridge heater 2.
Fig. 5 has represented the detailed structure of injector controlled on above-mentioned control principle basis.
With reference to Fig. 5, motor 20 and 21 connects with the shell 40 that is fixed on the injector.Gear 41 and 42 is contained on the rotating shaft 20A of motor 20, and gear 43 and 44 is installed in the rotating shaft 21A of motor 21.Gear 41 to 44 is by being connected in rotating shaft 20A and the 21A clutch 45 and 46 transmission of drive force of end separately.Shell 40 is supporting shaft 47A and 48A rotatably, and this power transmission shaft 47A and 48A be then by clutch 47 and 48 transmission of drive force, gear 49 and 50 and gear 51 and 52 be installed in respectively on power transmission shaft 47A and the 48A.Gear 49 and 50 is by being connected in a clutch of 30A end 60 and being contained in gear 61,62 and 63 engagements on the power transmission shaft 30A or throwing off, this power transmission shaft 30A is rotatably by shell 40 1 end portion supports, driving force is delivered to make-up machine, i.e. the mold cramping element 39 of mould 30 among Fig. 5.The other end of power transmission shaft 30A is rotatably being supported by the shell 35 of mould 30.Gear 36 is housed being arranged on the power transmission shaft 30A of shell 35.This gear 36 and gear 37 engagements are delivered to power transmission shaft 38 to driving force, move or sliding axle 38A and 38B on mold cramping element 39.Power transmission shaft 1A is installed in the shell 40 and at one end connects with screw rod 1 in the injector cartridge heater 2 and gear 53 is housed on axle 1A.Gear 53 also is installed in by bearing and is connected on the power transmission shaft 54 in the gear 53.According to said structure; injector just can be finished various operations, as the clamping element 39 that moves moulds before relying on gets final product the two halves of clamping mold, increase clamping pressure; inject and insert molten resin to mould 30; measurement and cooling are by plasticized resin, and the nozzle segment 5 of mobile backward cartridge heater 2 reduces mold cramping pressure; mobile backward clamping element; open the mould two halves, release molded product from mold cavity, this resin injects and molded operation can be repeatedly so that obtain moulded product continuously.
Before reference table is shown in the injection molding operation; the accompanying drawing 5 of injector state; motor 20 at first is driven when two halves that need clamping mold and needs increase pressure; by the order that drives rotating shaft 20A gear 50 and gear 62 driving force of motor 20 is delivered to power transmission shaft 30A; rotatablely moving of power transmission shaft 30A is delivered to power transmission shaft 38 and makes its rotation by gear 36 and 37; thus; move forward mold cramping parts 39; be to move right among Fig. 5; decide stop position when mold cramping element 39 is parked in to give, clamping pressure reaches when giving fixed point, clutch 64 commutations; cut off by the transmission of gear 62 to gear 36 power; and clutch 45 and 47 commutations only make a 47A rotation, move forward shell 40; be to be moved to the left among Fig. 5, make the opening of the nozzle segment 5 of cartridge heater 2 near to or in contact with mould 30.Nozzle segment 5 is a shell 40, is bounced back by motor 20 reverse drive.
When needs injected mould to molten resin, motor 20 and 21 was driven by clutch 45 and 46 commutations, by the gear (not shown) rotation of gear 41 and 42 is delivered to gear 62 and 63 respectively.Therefore, by clutch 60 commutations the rotation of gear 62 and 63 is delivered to gear 55. Motor 20 and 21 rotatablely move and be delivered to power transmission shaft 54 and 1A by gear 55 thus, move forward screw rod 1, so just the molten resin of cartridge heater 2 are injected mould 30 by nozzle segment.When needs carry out the measurement of resin, have only motor 21 to be driven, make rotatablely moving of motor 21 be delivered to screw rod 1 by gear 43 and another gear (not shown) and gear 52, axle 48A, gear 51, gear 49, gear 61 and gear 53.Synchronous with motor 21 these operating process, motor 20 equally also is driven, rotatablely moving of motor 20 is delivered to screw rod 1 by gear 42 and another gear (not shown), gear 62, clutch 60, gear 55, axle 54 and axle 1A equally, back pressure is provided and measures amount of resin to screw rod 1.
The mould two halves of die device 30 are by the opposite mode drive motor 20 of above mold cramping operation, make mold cramping element 39 retractions and open.
The detailed structure of control module 10 and operate in reference to the accompanying drawings 6 and be illustrated to accompanying drawing 16 among Fig. 3.
The signal So that is produced by position control component 11A has represented in Fig. 6, GP in Fig. 6
1, GP
2And GP
3Represent the gain of position control loop and position control component is operated according to the flow process of Fig. 7, signal So is input to speed control element 11B, the back pressure command signal Hi that is converted to revolution command signal Ki shown in Figure 8 then and has relation shown in Figure 9.In this case, speed control element 11B operates according to Figure 16 flow process.Figure 11 represents another kind of relation between revolution command signal Ki and the back pressure command signal Hi.Figure 12 represents the operation of speed control element 11B.Figure 13 is expression produces a kind of curve of making time spent signal Ho when back pressure control element 12 a example, the operation table of back pressure control element 12 is shown in the flow process of Figure 14, in Figure 13 and Figure 14, GB represents the back pressure ride gain, and Homax and Homin represent back pressure maximum and minimum of a value respectively.In addition, the Response Table of revolution control element 15 is shown among Figure 15, and its operating process is illustrated in the flow process of Figure 16, and in Figure 15 and 16, A, B, C and D are respectively parameter, and the value of parameter D is D={ A(B+C) }/(A+C), C
1And C
2Be variable, Komax and Komin representative are equivalent to the command signal of revolution maximum and minimum of a value.
Figure 17 represents another embodiment of control module 10 of the present invention.The element of wherein identical reference number representative is identical with those elements shown in Fig. 3.Difference Se between position command Si and the screw position feedback signal Sf directly imports back pressure control element 12, and screw back pressure signal Pi sends from the electrical power amplifier 13 that connects with control element 12 effectively then, and drive motor 20 is also controlled screw position.Revolution instruction Ki indicates a constant value independently.Difference Se input revolution control element 15 between instruction Ki and the screw rod revolution feedback signal Rf.Electrical power amplifier 16 sends the screw rod revolution signal Ri of response from the signal Ko of control element 15, drive motor 21.
Figure 18 represents the curve map of an embodiment in Figure 17 of Fig. 4.According to Figure 18, the revolution n of screw rod 1 is expressed as a numerical value ns, and this is because revolution instruction Ki is a constant value.For back pressure P, difference signal Se measures the operation starting point at resin and gets higher value between position command Si and the screw position feedback signal Sf, and back pressure control element 12 gains to produce with difference signal Se inverse ratio, and produces frequency characteristic thus, with the compensation closed loop characteristic.For this reason, measuring process is at first with relatively low back pressure P
4And at relative fair speed V
4Beginning is to quicken to measure operation.Because the numerical value of difference Se reduces gradually, the back pressure P of screw rod 1 increases thus, as P
3→ P
2→ P
1, screw motion speed V reduces gradually, as V
3→ V
2→ V
1(as shown in figure 18).When back pressure reaches PS screw motion speed near null value, screw rod reaches by position command Si and gives fixed physical location, in this position, and the screw rod stop motion, measuring process is then promptly finished.Therefore, because screw speed reduces gradually, screw rod can be parked in accurate location with high accuracy, like this, just can accurately measure amount of resin.
Figure 21 represents that reference number is another embodiment of the control module of 10B according to the present invention, and in this embodiment, the element of identical reference number representative is identical with those elements among Fig. 3.The difference signal Se of position command Si and screw position feedback signal Sf is with the essentially identical mode input position of mode control element 11B among above-mentioned Fig. 3, but the output signal So from control element 11B is deducted from screw rod revolution feedback signal Sf, difference signal Ke directly imports revolution control element 15 therebetween, then output signal Ko input motor 20 from control element 15, as output signal Ri by electrical power amplifier 16, make screw rod 1 rotation, according to position command Si screw rod 1 is parked in then and gives allocation.In screw rod resin measuring process, back pressure instruction Hi always keeps constant value.Back pressure instruction Hi input back pressure control element 12 passes through electrical power amplifier 13 input motors 20 then as its output signal Pi, provides moment of torsion to screw rod 1, to produce the back pressure Ps of constant value.
Figure 22 represents and Fig. 4 or similar curve shown in Figure 180.According to Figure 18, back pressure P measures constant pressure value P s of expression in the operation at resin, screw rod 1 according to bigger position difference Se when initial with higher revolutions n
4Rotation is then because difference Se reduces to impel revolution n to reduce, as n
3→ n
2→ n
1, when screw rod 1 according to position command Si near giving allocation, revolution reduces to n
3, screw motion speed is reduced to the V near null value equally
0, screw rod 1 just is parked in exactly and gives allocation, measures operation like this and can finish.Therefore, revolution n is defined as getting high value when measuring process is initial, reduce gradually then, make screw rod be parked in the position of determining by position command Si exactly, measurement operation required time is reduced, and screw rod also can be parked in thus and give allocation, accurately measures amount of resin.
As a result, according to injector of the present invention, resin is measured operation and can be finished by change and the setting signal that external factor or interference (as: used resinous type or form, the shape of mould, variations in temperature, resin temperature etc.) have nothing to do.In addition, because the resin measuring intervals of TIME can reduce, the production efficiency of moulded product can improve in the mode of saving the energy, and the quality of moulded product equally also can improve.
As mentioned above, although the position of screw rod 1 is by screw rod revolution and the control of its back pressure, but owing to measure various operational circumstances in the operation at resin, constitute external disturbance as variations in temperature, humidity, plasticizing situation and resin feed quantity, the dynamic characteristic of screw rod may depart from gives the state characteristic of determining earlier, even the position of screw rod finally is controlled at the position of being determined by position command Si, but vibration or excess impact may take place in screw rod in measuring operation.These phenomenons may cause the compression that resin is unnecessary nocuously, and resin pressure reduces, and resin flows out from nozzle 5, or resin reverse flow material bin 3.Therefore, even various operating parameters change or change the dynamic characteristic that does not also influence screw rod 1 with regard to the speed of needs control screw rod and position and in measuring process.
These require can satisfy with the present invention on the basis of Figure 23 and 24 control principles of representing.With reference to Figure 23, suppose screw rod 40 to the right with V in tube 41, move (this move be since from the screw rod left side to the right between power Fs that screw rod 40 applies and Fr the difference f of power caused), at this moment, Equation of Motion is changed by Laplace transform, to obtain transforming function transformation function V(f in control system), this function representation is:
V（f）＝ (V)/(f) ＝ 1/(Ms+D) ……（1）
Wherein: M: inertia mass;
D: the viscosity coefficient of resin.
Figure 24 is the block diagram of expression speed control loop system, and as shown in Figure 3, it comprises the above-mentioned type (function V(f)) motion control unit 43 and speed loop gain device 42(multiplier (-icator) G).The signal differentiation that the feedback signal of native system is sent by screw position sensor 26 and obtaining, therefore, control system shown in Figure 24 constitutes during for this system-based at screw speed.Relation is used in kinetic control system 43 to equation (1) and is calculated by following between Figure 24 medium velocity input command N i and the speed output order No:
(No)/(Ni) ＝ (G)/(Ms+D+G) ……（2）
Figure 25 is the block diagram of an embodiment of presentation graphs 3 control systems, wherein, output signal No adjusts input signal NA with respect to screw speed, be fed back to input signal, difference Ne between output signal No and the input signal NA is input to speed loop gain device 42, and this speed is input to motion control unit 43 then.Output signal No feeds back to input signal by booster element 44 equally, and the gain K of booster element is produced by suitable control element 45, and speed command Ni and output signal No import this control element 45 to obtain suitable control.For control system shown in Figure 25, speed command Ni and velocity output signal No are following relation and calculate:
(No)/(Ni) ＝ (G)/(Ms+D+G-G·K) ……（3）
Decide screw speed command N i when input when giving, screw rod 1 is with speed No motion, but when the viscosity coefficient of molten resin 6 changed to D+ △ D, the denominator of equation (3) was changed into:
MS+D+G+（△D-G·K） ……（4）
Therefore, when △ D=GK, that is:
K＝ (△D)/(G) ……（5）
Equation (3) equals equation (2) and can be cancelled by the viscosity variable △ D that certain reason causes.Like this, when variable △ D existed, the gain K of booster element 44 was determined by equation (5), thus, compensation is in the variation of screw unit medium viscosity coefficient, because variable △ D is with external factor, as temperature, variation, variable △ D should directly be measured by any specific process or suitable method.Obtaining a kind of method of variable △ D on the actual measurement basis will narrate below.Step response and and obtain as the speed input signal of equation (2) by the input step signal, and the response that obtains change into anti-Laplace transform as following equation g(t):
g（t）＝α
-1｛ 1/(S) - (No)/(Ni) ｝
＝α
-1｛ (G)/(S（Ms+D+G）) ｝
=(G)/(D+G) { 1-index ((D+G)/(M)) t }
……（6）
This equation g(t) represents by curve shown in Figure 26.During the time constant of curve, alphabetical M represents inertia mass, alphabetical G representation speed loop gain in considering Figure 26.Because inertia mass and loop gain are given value, viscosity coefficient D can be calculated by the time constant in the actual measurement that obtains step response, and, owing to step response numerical value can be obtained by time Series Processing step response easily.Therefore; viscosity coefficient D can set easily; in other words, equation (6) is to be set and calculated by suitable control element 45 shown in Figure 25, to calculate at the injector viscosity coefficient D under element or the part situation about suitably being adjusted in the time started separately.Fix time later by measurements and calculations equation (6) once more giving, can draw variable △ D, obtain the gain K of booster element 44 then with equation (5) at the viscosity coefficient D of former measurement.Characteristic by equation (2) representative can be obtained by the gain K that adopts booster element 44, and the measurement operation is accomplished under the situation identical with the above-mentioned injector time started.
Figure 27 represents according to the gain K calculating of above-mentioned control system block diagram shown in Figure 3 and the coupling of measuring.With reference to Figure 27, gain K at first obtains with said method corresponding to the control element 45 that matches, data input instruction Value Operations element 11, back pressure control element 12 and the revolution control element 15 of gain K.At instruction executive component 11, various definite values change according to the gain K of output in back pressure control element 12 and the revolution control element 15.
Control method according to this embodiment, even the temperature and humidity that resin is measured the various situation resins that operation requires with and the plasticizing situation change and can both automatically adjust or be defined as optimal state, measure in the operation and will carry out unnecessary pressurization or decompression with regard to having eliminated like this, and prevent that resin from flowing out and the reverse flow material bin from the cartridge heater nozzle segment the resin of measuring at resin.This just provide a kind of can be gratifying resin measure the injector of operation.
Figure 28 still represents the embodiment of the control system of another enforcement control method of the present invention.Among Figure 28, adjust between input signal NA and the screw speed output signal No after the relation having considered screw speed, constitute speed control loop Vc, in control loop Vc, output signal No feeds back to input signal, the output signal No of input and the difference Ne input speed loop gain device 42 between the input signal NA, then, from the signal input motion control system 43 of loop gain device 42 outputs.Difference NN input gain element 44 between velocity output signal No and the observer 50, gain K multiplied signals NB by constant and booster element 44 feeds back to screw speed command N i, the speed of difference is adjusted input signal NA input speed control loop Vc between signal Ni and the NB, observer 50 constitutes speed control loop with control loop Vc identical characteristics by element 51 and 52, calculates respectively and measuring speed loop 42 and kinetic control system 43 with the screw speed command N i by input.
In the theoretical research of control system with said structure, only change with external factor such as temperature with respect to resin viscosity coefficient D every in the equation (2), and about the every of gain amplifier G and inertia mass M for constant substantially quantitative really.Now, the hypothesis calculated value of supposing viscosity coefficient is DD, and then the kinetic control system 52 based on the DD value is defined as equation VA(f), because external condition such as variations in temperature, and when making the situation that equation (2) changes, equation VA(f) be expressed as:
VA（f）＝ (G)/(Ms+DD+G) ……（7）
On the basis of above-mentioned situation, relation is calculated by following formula between the screw speed command N i of control system shown in Figure 28 and the output speed No:
(NO)/(Ni) ＝ (G)/(Ms+DD+G) · (Ms+DD+G+K·G)/(Ms+D+G+K·G)
……（8）
By equation (8) under the very big situation of gain K, if following formula is set up:
K·G＞＞D+G ……（9）
K·G＞＞DD+G ……（10）
Equation (8) then is expressed as:
(No)/(Ni) = (G)/(Ms+DD+G) ……（11）
Therefore, because therefore the response of whole system, measures the influence that operation is not subjected to resin viscosity coefficient D in the screw rod system by equation (11) decision in resin measurement operation.In other words, by equation (11), gain G and inertia mass M are determined value, not influenced by external condition, viscosity coefficient DD is calculated by default, thereby measures operation and not influenced by external condition and the influence that only is subjected to determine gain K, to satisfy the situation that equation (9) and (10) are supposed.Observer 50 can not only be by simulated operation, and can finish hypothesis by the numerical calculation machine operation and calculate, gain K can by the stability of system and fast response determine.
In the above-described embodiments, the revolution n of screw rod 1 is detected by the sensor 25 that is connected in motor 21 effectively, but revolution n can be by gear or current of electric detection, and the position of screw rod 1 can be by the position probing of transmission platform 24 and ball nut 23.In addition, direct current or ac motor can use, and the motion of screw rod can be by being used in combination ball screw rod and ball nut or being realized by the guider under the Motor Drive.
Be to be understood that various improvement and conversion all are that the scope of conspicuous, following appended claims just comprises this conspicuous improvement and variation to those skilled in the art under the present invention.
Claims (3)
1, a kind of method of in resin measurement operation, controlling injector, this injector comprises a speed control system, a kinetic control system and a booster element; This speed control system is furnished with a speed loop gain element, and the difference between screw speed instruction and screw speed signal is imported this speed loop gain element; Should want controlled kinetic control system to comprise a screw rod and a screw actuator; Said method comprises the steps:
Provide and have and observation device above-mentioned speed control system identical characteristics and that have the output signal of above-mentioned screw speed instruction; Multiply by above-mentioned screw speed signal and from the difference between the output signal of above-mentioned observation device by a constant;
Output signal after so just obtaining to multiply each other and the difference between the instruction of above-mentioned screw speed;
The above-mentioned difference that is obtained by above-mentioned steps directly is used as the screw speed control signal.
2, according to the process of claim 1 wherein that above-mentioned observation device is by the simulated operation assumed calculation.
3, according to the process of claim 1 wherein that above-mentioned observation device is by the digital computer assumed calculation.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 85105528 CN1011299B (en) | 1985-06-25 | 1985-06-25 | Injection molding machines |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 85105528 Division CN1011299B (en) | 1985-06-25 | 1985-06-25 | Injection molding machines |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1046118A CN1046118A (en) | 1990-10-17 |
| CN1014964B true CN1014964B (en) | 1991-12-04 |
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Family Applications (3)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 90102761 Expired CN1014964B (en) | 1985-06-25 | 1985-06-25 | Injection molding machines and methods for controlling same |
| CN 90102760 Expired CN1013653B (en) | 1985-06-25 | 1985-06-25 | Injection molding machine controlling method |
| CN 85105528 Expired CN1011299B (en) | 1985-06-25 | 1985-06-25 | Injection molding machines |
Family Applications After (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 90102760 Expired CN1013653B (en) | 1985-06-25 | 1985-06-25 | Injection molding machine controlling method |
| CN 85105528 Expired CN1011299B (en) | 1985-06-25 | 1985-06-25 | Injection molding machines |
Country Status (1)
| Country | Link |
|---|---|
| CN (3) | CN1014964B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3649714B2 (en) | 2002-11-05 | 2005-05-18 | ファナック株式会社 | Control device for injection molding machine |
| JP4504800B2 (en) * | 2004-12-20 | 2010-07-14 | 東洋機械金属株式会社 | Metering control method for injection molding machine and injection molding machine |
| CN100450746C (en) * | 2005-03-11 | 2009-01-14 | 华南理工大学 | Material along path feed back dynamic mixing extrusion method and equipment |
| KR101149358B1 (en) * | 2008-11-18 | 2012-05-30 | 금호석유화학 주식회사 | An Apparatus for Compositing conducting composites and method thereof. |
| CN111907020A (en) * | 2020-07-27 | 2020-11-10 | 湖北帮友科技有限公司 | Injection molding machine micro-injection device capable of realizing high-speed and high-precision injection |
-
1985
- 1985-06-25 CN CN 90102761 patent/CN1014964B/en not_active Expired
- 1985-06-25 CN CN 90102760 patent/CN1013653B/en not_active Expired
- 1985-06-25 CN CN 85105528 patent/CN1011299B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| CN85105528A (en) | 1986-12-24 |
| CN1011299B (en) | 1991-01-23 |
| CN1013653B (en) | 1991-08-28 |
| CN1046117A (en) | 1990-10-17 |
| CN1046118A (en) | 1990-10-17 |
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