CN105328887A - Melt flow speed and solidification rate detection method based on sensing system for melt state in mold - Google Patents
Melt flow speed and solidification rate detection method based on sensing system for melt state in mold Download PDFInfo
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- CN105328887A CN105328887A CN201510762910.8A CN201510762910A CN105328887A CN 105328887 A CN105328887 A CN 105328887A CN 201510762910 A CN201510762910 A CN 201510762910A CN 105328887 A CN105328887 A CN 105328887A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/17—Component parts, details or accessories; Auxiliary operations
- B29C45/76—Measuring, controlling or regulating
- B29C45/77—Measuring, controlling or regulating of velocity or pressure of moulding material
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C2945/00—Indexing scheme relating to injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould
- B29C2945/76—Measuring, controlling or regulating
- B29C2945/76003—Measured parameter
- B29C2945/76033—Electric current or voltage
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C2945/00—Indexing scheme relating to injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould
- B29C2945/76—Measuring, controlling or regulating
- B29C2945/76003—Measured parameter
- B29C2945/76066—Time
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C2945/00—Indexing scheme relating to injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould
- B29C2945/76—Measuring, controlling or regulating
- B29C2945/76177—Location of measurement
- B29C2945/76254—Mould
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C2945/00—Indexing scheme relating to injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould
- B29C2945/76—Measuring, controlling or regulating
- B29C2945/76451—Measurement means
- B29C2945/76454—Electrical, e.g. thermocouples
Abstract
The invention discloses a melt flow speed and solidification rate detection method based on a sensing system for the melt state in a mold. The detection method comprises the steps that point electrodes of the sensing system for the melt state in the mold are installed at key points in the injection molding process, a point electrode capacitor of the sensing system for the melt state in the mold is connected with a state recognizing system through a capacitance measuring unit, wherein the key points in the injection molding process are located in the mold; a sampling cycle is set, the output voltage of the point electrode capacitor sensor is collected regularly according to the set sampling cycle; calculation is carried out according to the collected output voltage and sampling moments, and the melt flow speed and the solidification rate in the injection mold are obtained. According to the detection method, the melt state in the mold can be detected as long as the point electrodes of the point electrode capacitor sensor are installed at the key points in the mold in the injection molding process and the measuring unit and the state recognizing system are matched, flexibility is high, and adaptability is wide. The detection method can be widely applied to the injection molding field.
Description
Technical field
The present invention relates to injection molding art, especially a kind of melt flow based on melt state sensory perceptual system in mould and freezing rate detection method.
Background technology
In polymer shaping process, particularly injection moulding process, On-line sampling system or detect the flow rate of macromolecule melt in injection mold and freezing rate, has vital effect for the detection of whole injection moulding process and the prediction of end product quality.
In traditional injection moulding process, the flow rate of melt in injection mold and freezing rate detection method mainly comprise:
1), by its dependent variables such as measurement mode cavity pressure, cavity surface temperatures indirectly infer the flow rate and freezing rate that melt in mould, but the method operates easy not.
2), mounting glass die cavity in a mold, by high speed camera shooting macromolecule melt flow rate in a mold and freezing rate.This method provide good experiment information, but due to melt completely different in the movable pole point process on used the in the industry metal die surface of glass surface and its, the method cannot be applied in industry, and range of application is less.
3), melt flow rate in a mold and freezing rate is detected by ultrasonic pulse reflection method.The method detects the position of flowing in a mold melt front end according to macromolecule and air to hyperacoustic differential declines degree.In a mold, install multiple sensor, when melt front end flow to the installation site of sensor, the amplitude that ultrasonic pulse reflects changes immediately, obtains the position that melt flows in a mold thus.But the position that the method can only be installed at sensor detects the front end of melt, that can only provide interruption or discrete melt flow rate (MFR) and freezing rate information are not accurate enough.
In order to overcome above defect, someone proposes and adopts the method for flat capacitance sensor (by plate condenser and corresponding capacitance measurement circuit) to detect the melt flow rate (MFR) of melt in injection mold and freezing rate information.This capacitance sensor utilizes the plastic melt flow rate and freezing rate information that are arranged in two flat pole perception die cavitys of die cavity both sides.Experimental result finds that plate capacitor can the correct materials behavior of the plate plastic product of on-line measurement in die cavity effectively, but the two poles of the earth of the method middle plateform capacitor are difficult to be arranged in the mould (mould as nonplanar structure) of surface texture complexity, and flexibility ratio is lower and applicability is narrower.
Summary of the invention
In order to solve the problems of the technologies described above, the object of the invention is: provide that a kind of flexibility ratio is higher and applicability is wider, based on melt flow and the freezing rate detection method of melt state sensory perceptual system in mould.
The technical solution adopted for the present invention to solve the technical problems is:
Based on melt flow and the freezing rate detection method of melt state sensory perceptual system in mould, comprising:
A, the point electrode of melt state sensory perceptual system in mould is arranged on the key point place of injection moulding process, and the point electrode capacitor of melt state sensory perceptual system in mould is connected with state recognition system by capacitance measurement unit, wherein, the key point of injection moulding process is in mould;
B, setting the sampling period and according to setting sampling period timing the output voltage of point electrode capacitance sensor is gathered;
C, according to gather output voltage and sampling instant calculate, draw the melt flow in injection mold and freezing rate.
Further, the key point of described injection moulding process is the glue-feeder of injection moulding process, last filling position or last cool position.
Further, calculate according to the output voltage gathered and sampling instant in described step C, draw this step of melt flow in injection mold, it comprises:
C11, according to gather output voltage calculate melt front end in the position of each sampling instant t
x t with corresponding point electrode capacitance;
C12, respectively acquisition are positioned at
x t with
x t-1
there is the sampling instant of change in the point electrode capacitance at place
t t with
t t-1
;
C13, occur that calculus of differences is carried out in the sampling instant of change according to the melt front position obtained and point electrode capacitance, thus obtain the melt flow in current time injection mold.
Further, described in state step C13, it is specially:
According to the melt front position obtained
x t ,
x t-1
the sampling instant of change is there is with point electrode capacitance
t t ,
t t-1
carry out calculus of differences, thus obtain the melt flow in current time injection mold, the computing formula of carrying out calculus of differences is:
，
Wherein,
v t for the flowing velocity of melt between two point electrodes,
x t be
tthe position of individual point electrode,
x t-1
be
t-1the position of individual point electrode,
t t be
tthe moment that the sudden change of individual capacitance occurs is the
t-1the moment that individual capacitance sudden change occurs.
Further, calculate according to the output voltage gathered and sampling instant in described step C, draw this step of freezing rate in injection mold, it comprises:
C21, generate output voltage and time curve according to the output voltage gathered, sampling instant;
C22, output voltage to find out the terminal of cooling stage and corresponding start/stop time in time curve;
C23, the freezing rate calculated according to the terminal of cooling stage and corresponding start/stop time in injection mold.
Further, after described step C, be also provided with step D, described step D, it is specially: carry out closed loop adjustment according to the melt flow in injection mold to the flow regime of injection process melt in die cavity, thus realize the Uniform Flow of melt in die cavity.
Further, after described step C, be also provided with step e, described step e, it is specially:
Determine to solidify the end time according to the freezing rate in injection mold, and then obtain best cool time.
Further, in described mould, melt state sensory perceptual system comprises point electrode capacitor sensor and state recognition system, described point electrode capacitor sensor comprises point electrode capacitor and capacitance measurement unit, one of described point electrode capacitor is very arranged on the point electrode in the quiet mould of mould, another of described point electrode capacitor is very arranged on the metal electrode on mould dynamic model, described point electrode is all connected with capacitance measurement unit with metal electrode, and the output of described capacitance measurement unit is connected with the input of state recognition system.
Further, described electrode capacitor sensor also comprises nested and helical bolt, in described point electrode, the top of the shaft shoulder coordinates with the locating hole of mould the location realizing upward direction, and in described point electrode, the bottom of the shaft shoulder is by nested coordinating with helical bolt, realizes location in downward direction.
Further, in described mould, melt state sensory perceptual system comprises point electrode capacitor sensor and state recognition system, described point electrode capacitor sensor comprises point electrode capacitor and capacitance measurement unit, one of described point electrode capacitor is very arranged on the point electrode 1 on mould dynamic model thimble, another of described point electrode capacitor is very arranged on the metal electrode on the quiet mould 7 of mould, described point electrode 1 is all connected with capacitance measurement unit with metal electrode, and the output of described capacitance measurement unit is connected with the input of state recognition system.
The invention has the beneficial effects as follows: only the point electrode of point electrode capacitance sensor need be arranged on the injection moulding process key point place in mould, and conjunction measuring unit and state recognition system just can complete the detection of melt state in mould, reduce the impact of die surface structure on mould state-detection process, thus point electrode capacitor sensor can be arranged in the mould of surface texture complexity, flexibility ratio is higher and adaptability is wider.Further, point electrode capacitor sensor comprises point electrode, nested and helical bolt, point electrode realizes the location of point electrode by the shaft shoulder with working in coordination between nested, helical bolt, makes point electrode ensure that pole plate does not enter die cavity at the pressure bearing plastics in die cavity, more simultaneously.Further, directly utilize thimble as point electrode, do not need to change mould structure, convenient and be generally suitable for.
Accompanying drawing explanation
Below in conjunction with drawings and Examples, the invention will be further described.
Fig. 1 the present invention is based on the melt flow of melt state sensory perceptual system in mould and the overall flow figure of freezing rate detection method;
Fig. 2 is that the present invention calculates according to the output voltage gathered and sampling instant, draws the flow chart of the melt flow step in injection mold;
Fig. 3 is that the present invention calculates according to the output voltage gathered and sampling instant, draws the flow chart of the freezing rate step in injection mold;
Fig. 4 is the overall structure figure of melt state sensory perceptual system in mould of the present invention;
Fig. 5 is the structural representation of point electrode capacitor of the present invention;
Fig. 6 is the composition structure chart of capacitance measurement unit of the present invention;
Fig. 7 is the configuration diagram of some electrode capacitors of the embodiment of the present invention;
Fig. 8 is the output voltage-time graph of the embodiment of the present invention four.
Reference numeral: 1, point electrode; 2, insulating barrier; 3, nested; 4, helical bolt; 5, wiring hole; 6, the shaft shoulder; 7, quiet mould; 8, die cavity; 9, object is measured; 10, earth electrode.
Detailed description of the invention
With reference to Fig. 1, based on melt flow and the freezing rate detection method of melt state sensory perceptual system in mould, comprising:
A, the point electrode of melt state sensory perceptual system in mould is arranged on the key point place of injection moulding process, and the point electrode capacitor of melt state sensory perceptual system in mould is connected with state recognition system by capacitance measurement unit, wherein, the key point of injection moulding process is in mould;
B, setting the sampling period and according to setting sampling period timing the output voltage of point electrode capacitance sensor is gathered;
C, according to gather output voltage and sampling instant calculate, draw the melt flow in injection mold and freezing rate.
Be further used as preferred embodiment, the key point of described injection moulding process is the glue-feeder of injection moulding process, last filling position or last cool position.
With reference to Fig. 2, be further used as preferred embodiment, calculate according to the output voltage gathered and sampling instant in described step C, draw this step of melt flow in injection mold, it comprises:
C11, according to gather output voltage calculate melt front end in the position of each sampling instant t
x t with corresponding point electrode capacitance;
C12, respectively acquisition are positioned at
x t with
x t-1
there is the sampling instant of change in the point electrode capacitance at place
t t with
t t-1
;
C13, occur that calculus of differences is carried out in the sampling instant of change according to the melt front position obtained and point electrode capacitance, thus obtain the melt flow in current time injection mold.
Be further used as preferred embodiment, described in state step C13, it is specially:
According to the melt front position obtained
x t ,
x t-1
the sampling instant of change is there is with point electrode capacitance
t t ,
t t-1
carry out calculus of differences, thus obtain the melt flow in current time injection mold, the computing formula of carrying out calculus of differences is:
，
Wherein,
v t for the flowing velocity of melt between two point electrodes,
x t be
tthe position of individual point electrode,
x t-1
be
t-1the position of individual point electrode,
t t be
tthe moment that the sudden change of individual capacitance occurs is the
t-1the moment that individual capacitance sudden change occurs.
With reference to Fig. 3, be further used as preferred embodiment, calculate according to the output voltage gathered and sampling instant in described step C, draw this step of freezing rate in injection mold, it comprises:
C21, generate output voltage and time curve according to the output voltage gathered, sampling instant;
C22, output voltage to find out the terminal of cooling stage and corresponding start/stop time in time curve;
C23, the freezing rate calculated according to the terminal of cooling stage and corresponding start/stop time in injection mold.
Be further used as preferred embodiment, also step D is provided with after described step C, described step D, it is specially: carry out closed loop adjustment according to the melt flow in injection mold to the flow regime of injection process melt in die cavity, thus realize the Uniform Flow of melt in die cavity.
Be further used as preferred embodiment, after described step C, be also provided with step e, described step e, it is specially:
Determine to solidify the end time according to the freezing rate in injection mold, and then obtain best cool time.
With reference to Fig. 4 and Fig. 5, be further used as preferred embodiment, in described mould, melt state sensory perceptual system comprises point electrode capacitor sensor and state recognition system, described point electrode capacitor sensor comprises point electrode capacitor and capacitance measurement unit, one of described point electrode capacitor is very arranged on the point electrode 1 in the quiet mould 7 of mould, another of described point electrode capacitor is very arranged on the metal electrode on mould dynamic model, described point electrode 1 is all connected with capacitance measurement unit with metal electrode, the output of described capacitance measurement unit is connected with the input of state recognition system.
Point electrode can be installed on the quiet mould of mould by the present invention, and the holding wire that point electrode is drawn does not need with the variation of mould dynamic model and changes, to make the signal obtained more stable.
With reference to Fig. 5, be further used as preferred embodiment, described electrode capacitor sensor also comprises nested 3 and helical bolt 4, in described point electrode 1, the top of the shaft shoulder 6 coordinates with the locating hole of mould the location realizing upward direction, in described point electrode 1 shaft shoulder 6 bottom by nested 3 with the coordinating of helical bolt 4, realize location in downward direction.
Be further used as preferred embodiment, in described mould, melt state sensory perceptual system comprises point electrode capacitor sensor and state recognition system, described point electrode capacitor sensor comprises point electrode capacitor and capacitance measurement unit, one of described point electrode capacitor is very arranged on the point electrode 1 on mould dynamic model thimble, another of described point electrode capacitor is very arranged on the metal electrode on the quiet mould 7 of mould, described point electrode 1 is all connected with capacitance measurement unit with metal electrode, and the output of described capacitance measurement unit is connected with the input of state recognition system.
The present invention also can, by (such as adding insulating barrier) after thimble is carried out particular design, directly utilize thimble as point electrode.In this case, point electrode is exactly that now corresponding with point electrode metal electrode is exactly directly metal surface corresponding to mould, namely corresponding with part in point electrode insulating barrier area on the dynamic model of mould (because thimble is all generally) on dynamic model.The benefit of this design does not need to change (because each mould necessarily have thimble) to mould, very convenient and be easy to realize.
Below in conjunction with Figure of description and specific embodiment, the present invention is described in further detail.
Embodiment one
With reference to Fig. 4-7, the first embodiment of the present invention:
The point electrode capacitance sensor that in the injection mold that the present invention is based on point electrode, melt state sensory perceptual system comprises state recognition system and is made up of point electrode capacitor, capacitance measurement unit.Respectively this two large divisions is introduced below.
(1) point electrode capacitance sensor
In order to solve the demand of the on-line measurement of the product (such as phone housing) based on writing board shape, someone designs and has processed plate capacitance sensor at present, but plate capacitor cannot be arranged in the baroque plastic product mould of cavity surface.Based on this demand, the present invention devises the on-line measurement problem that a kind of novel point electrode capacitor sensor solves complex surface plastic product.
Point-type sensor of the present invention both can play the effect of plate capacitance sensor by the form of array, also can rational deployment in the mould of non-planar surfaces structure, applicability is wider.Capacitance sensor plate designs of the present invention is single point shape (being generally 3 ~ 6mm circular), can by the key point place of difference layout at injection moulding process such as glue-feeder, last filling position, last cool position.
Point electrode capacitor sensor of the present invention comprises point electrode capacitor and capacitance measurement unit.
(1) point electrode capacitor
As shown in Figure 7, capacitor is formed between point electrode and grounding electrode plate.When tested plastic melt is placed between above-mentioned two electrodes, melt replaces air dielectric as medium and causes capacitance to raise, and the factor such as materials behavior, thickness, mold temperature of melt also can affect the change of capacitance in injection moulding process in addition.Therefore, the application of this configuration just can be monitored real-time procedural information by Real-Time Monitoring capacitance in a mold.Two metal electrodes of point electrode capacitor are contained in the two halves of mould respectively, and (half is quiet mould, and half is dynamic model, as shown in Figure 7.In the process that mould is closed, quiet mould is motionless, and dynamic model closes to quiet mould direction, and this two metallic plate is mutually isolated simultaneously), thus form two electrodes of capacitor.
In addition, because plate electrode and mould are all metal material, in order to reduce the complexity of design, the present invention only devises point electrode, and another electrode of point electrode capacitor is then replaced by the dynamic model of access capacitance measurement unit.As shown in Figure 7, one piece of corrosion resistant plate is arranged in dynamic model, forms a pole of point electrode capacitor, comprises the quiet mould part of point electrode without any need for amendment simultaneously, forms an other pole of point electrode capacitor.
The position relationship of the feature little for point electrode size and thimble and mould is considered, point electrode sensor of the present invention also can be designed to the shape identical with thimble and replace thimble, is arranged on the quiet mould of mould on the thimble being arranged on mould dynamic model and by metal electrode by point electrode.Such design can be formed by existing equipment quick transformation, does not need to change existing mould structure, only thimble need be carried out improving just can realize, avoid other processing mounting holes on mould, convenient and be generally suitable for.
(2) capacitance measurement unit
Capacitance measurement unit of the present invention is then primarily of three part compositions, as shown in Figure 6, wherein, the capacitance of capacitance-voltage modular converter to point electrode capacitor measure and capacitance is converted into analog voltage export, and output voltage and capacitance linear; The analog voltage of output is converted into digital quantity by the analog-to-digital conversion module of capacitance measurement unit; The acquisition module of capacitance measurement unit gathers the digital quantity that capacitance measurement unit exports and feeds back to state recognition system.
(2) state recognition system
State recognition system gathers and record at the digital quantity do not exported in the same time capacitance measurement unit, obtains output voltage-time graph, then analyzes this curve, can identify the state in mould residing for melt.
Embodiment two
With reference to Fig. 5, the second embodiment of the present invention:
For the consideration of reliability, point electrode capacitance sensor of the present invention divides three parts, is respectively point electrode, nested and helical bolt.The design of point electrode needs to consider its working environment.In a mold, point electrode should bear the pressure from plastics in die cavity, must ensure that again its pole plate does not enter die cavity, to avoid the impact on product quality.Therefore, point electrode plate needs to realize location in the two directions.As shown in Figure 5, the location of the present invention to point electrode is realized by the shaft shoulder, and shaft shoulder top coordinates with the locating hole of mould the location realizing upward direction; The bottom of the shaft shoulder then with nested arrangements, then to be coordinated with quiet mould mould by screw thread by helical bolt, realize location in downward direction.
Point electrode, nested, screwed plug three are designed to the structure cooperatively interacted by the present invention, realize point electrode capacitor sensor location in a mold and assembling.Point electrode relies on nested realization to locate with coordinating of bolt, to be fixed in quiet mould, and by the plastic state information in its surface induction mould.
Point electrode capacitor sensor needs when being installed on mould to process (as boring etc.) mould, and in order to make its better adaptability and cost-saving, also the part that mould changes can be made quiet mould module, remainder all makes identical structure.Like this for different products, when it needs to carry out different sensing station layouts, only need to process different quiet mould module, then by quiet mould module assembly in the groove of mould, significantly reduce producing cost and improve the applicability of mould.
In order to form capacitor, the two poles of the earth of capacitor must isolation mutually.The present invention uses electrical insulator to come other positions of isolating points electrode and mould, point electrode with nested between be provided with insulating barrier.
In addition, the position relationship of the feature little for point electrode size and thimble and mould is considered, point electrode sensor of the present invention also can be designed to the shape identical with thimble, replaces thimble.Such design can be formed by existing equipment quick transformation, does not need to change existing mould structure, only thimble need be carried out improving just can realize, avoid other processing mounting holes on mould, convenient and be generally suitable for.
Embodiment three
At the injection stage of injection moulding process, melt injects die cavity under the promotion of screw rod, and its flow regime in die cavity has vital effect to the quality of final products, particularly mechanical property.If melt has non-homogeneous constant melt flow rate in die cavity, then the coefficient of expansion of product each several part can be caused different, cause distortion and the distortion of product; And the flowing velocity of melt in die cavity is even, then can ensure that melt has uniform molecule and fiber orientation distribution, thus ensure the stable mechanical property of product.Based on above consideration, sensory perceptual system of the present invention is also by the multiple point electrode monitoring position of melt front end in die cavity, and then the flowing velocity of instant computing melt in die cavity, be closed-loop control injection process, the flowing realizing melt homogeneous constant provides Fundamentals of Measurement.
The implementation procedure that the present invention is based on the melt flow of melt state sensory perceptual system in mould is:
(1), two of point electrode capacitor electrodes are arranged on the both sides of die cavity, and point electrode capacitor is connected with state recognition system by capacitance measurement unit;
(2), state recognition system sets the sampling period and gathers the output voltage of point electrode capacitance sensor according to this sampling period timing;
(3), melt front end is calculated in the position of each sampling instant t according to the output voltage gathered
x t with corresponding point electrode capacitance;
Wherein, for specific injection moulding process, the relative dielectric constant k of macromolecular material fixes, so the position x of melt front end can be expressed as only with the function that capacitance C is variable, again because the capacitance C of output voltage V and capacitor is linear, therefore the function that it is variable that x also can be expressed as with output voltage V.Therefore, can realize determining the determination of melt front position and corresponding point electrode capacitance to the collection of capacitance measurement unit output voltage V.
(4), acquisition is positioned at respectively
x t with
x t-1
there is the sampling instant of change in the point electrode capacitance at place
t t with
t t-1
;
(5), according to the melt front position obtained
x t ,
x t-1
the sampling instant of change is there is with point electrode capacitance
t t ,
t t-1
carry out calculus of differences, thus obtain the melt flow in current time injection mold
v t ,
v t computing formula be:
。
Embodiment four
With reference to Fig. 1, Fig. 3 and Fig. 8, the fourth embodiment of the present invention:
The cooling stage of injection moulding process occupies the whole injection moulding process the longest time, cool time, deficiency can cause the distortion of product after the inconsistent and die sinking of shaping product, long cool time then can cause lower injection moulding efficiency, increases the cost of injection moulding process.Industrially at present accurately cannot learn best cool time, institute thinks guarantee product quality, generally needs field worker to use any cool time long by rule of thumb as far as possible.
According to of the present invention some capacitance sensor, then at cooling stage, the melt in die cavity enters process of setting because himself heat is run off by die cavity wall, and its high molecular dielectric constant can change (small change) along with the change of himself temperature.Dielectric constant has changed, and corresponds ground, and in mould, the voltage of melt sensor-based system exports and also changes along with the carrying out of process of setting.Based on above thinking, the present invention also can detect freezing rate according to the testing result of cooling stage system output voltage, determines to solidify the time terminated, and then obtains best cool time, improves injection moulding efficiency.
The implementation procedure that the present invention is based on the freezing rate of melt state sensory perceptual system in mould is:
(1), two of point electrode capacitor electrodes are arranged on the both sides of die cavity, and point electrode capacitor is connected with state recognition system by capacitance measurement unit;
(2), state recognition system sets the sampling period and gathers the output voltage of point electrode capacitance sensor according to this sampling period timing;
(3), state recognition system record gather output voltage and gather the moment, obtain corresponding output voltage-time graph;
(4), output voltage to find out the terminal of cooling stage and corresponding start/stop time in time curve;
As shown in Figure 8, in the matched moulds stage, dynamic model is drawn close to quiet mould, and mould inner capacitor two-plate spacing shortens.This change causes the capacitance of point electrode capacitor to increase gradually; Because output voltage linearly changes with electric capacity, so the magnitude of voltage also corresponding increase that capacitance measurement unit exports, till the relative distance between dynamic model and quiet mould no longer changes.At injection stage, because polymer dielectric constant is larger than air, along with macromolecule melt injects die cavity gradually, the capacitance of mould inner capacitor also increases gradually, and the output voltage values of capacitance measurement unit also increases thereupon; At packing stage; a small amount of melt is squeezed into the product contraction that die cavity causes to compensate melt cooling; now the output voltage of capacitance measurement unit also increases mutually, but relative to injection stage, and output voltage becomes slowly in the increasing degree in this stage and speed.After pressurize terminates, injection moulding process enters cooling stage, and significant change does not occur the capacitance of point electrode capacitor; When product solidifies fully, mould is opened, and the distance of electric capacity two interpolar becomes suddenly large, causes capacitance and output voltage to decline rapidly.Therefore by output voltage-time graph, state recognition system clearly can identify and solidify starting point (i.e. the starting point of cooling stage) voltage U 1, solidifies terminating point (i.e. the terminating point of cooling stage) voltage U 2 and initial time accordingly
t1, end time
t2.
(4), according to the freezing rate in the terminal voltage of cooling stage and the injection mold of start/stop time calculating accordingly.
At cooling stage, output voltage and the electric capacity of point electrode capacitor are linear, and electric capacity and dielectric constant are also linear, dielectric constant and temperature linear, temperature and concreting thickness linear, therefore the output voltage of concreting thickness and point electrode capacitor is linear.Therefore, according to solidifying starting point voltage U 1, solidifying terminating point voltage U 2 and corresponding initial time
t1, end time
tthe electric capacity C1 of 2 voltage U 1 and starting point point electrode of solidifying starting point is directly proportional, solidify terminating point (i.e. the terminating point of cooling stage) voltage U 2 can calculate average freezing rate.
More than that better enforcement of the present invention is illustrated, but the invention is not limited to described embodiment, those of ordinary skill in the art also can make all equivalent variations or replacement under the prerequisite without prejudice to spirit of the present invention, and these equivalent distortion or replacement are all included in the application's claim limited range.
Claims (10)
1., based on melt flow and the freezing rate detection method of melt state sensory perceptual system in mould, it is characterized in that: comprising:
A, the point electrode of melt state sensory perceptual system in mould is arranged on the key point place of injection moulding process, and the point electrode capacitor of melt state sensory perceptual system in mould is connected with state recognition system by capacitance measurement unit, wherein, the key point of injection moulding process is in mould;
B, setting the sampling period and according to setting sampling period timing the output voltage of point electrode capacitance sensor is gathered;
C, according to gather output voltage and sampling instant calculate, draw the melt flow in injection mold and freezing rate.
2. the melt flow based on melt state sensory perceptual system in mould according to claim 1 and freezing rate detection method, is characterized in that: the key point of described injection moulding process is the glue-feeder of injection moulding process, last filling position or last cool position.
3. the melt flow based on melt state sensory perceptual system in mould according to claim 2 and freezing rate detection method, it is characterized in that: calculate according to the output voltage gathered and sampling instant in described step C, draw this step of melt flow in injection mold, it comprises:
C11, according to gather output voltage calculate melt front end in the position of each sampling instant t
x t with corresponding point electrode capacitance;
C12, respectively acquisition are positioned at
x t with
x t-1
there is the sampling instant of change in the point electrode capacitance at place
t t with
t t-1
;
C13, occur that calculus of differences is carried out in the sampling instant of change according to the melt front position obtained and point electrode capacitance, thus obtain the melt flow in current time injection mold.
4. the melt flow based on melt state sensory perceptual system in mould according to claim 3 and freezing rate detection method, is characterized in that: described in state step C13, it is specially:
According to the melt front position obtained
x t ,
x t-1
the sampling instant of change is there is with point electrode capacitance
t t ,
t t-1
carry out calculus of differences, thus obtain the melt flow in current time injection mold, the computing formula of carrying out calculus of differences is:
，
Wherein,
v t for the flowing velocity of melt between two point electrodes,
x t be
tthe position of individual point electrode,
x t-1
be
t-1the position of individual point electrode,
t t be
tthe moment that the sudden change of individual capacitance occurs is the
t-1the moment that individual capacitance sudden change occurs.
5. the melt flow based on melt state sensory perceptual system in mould according to claim 2 and freezing rate detection method, it is characterized in that: calculate according to the output voltage gathered and sampling instant in described step C, draw this step of freezing rate in injection mold, it comprises:
C21, generate output voltage and time curve according to the output voltage gathered, sampling instant;
C22, output voltage to find out the terminal of cooling stage and corresponding start/stop time in time curve;
C23, the freezing rate calculated according to the terminal of cooling stage and corresponding start/stop time in injection mold.
6. the melt flow based on melt state sensory perceptual system in mould according to claim 1 and freezing rate detection method, it is characterized in that: after described step C, be also provided with step D, described step D, it is specially: carry out closed loop adjustment according to the melt flow in injection mold to the flow regime of injection process melt in die cavity, thus realize the Uniform Flow of melt in die cavity.
7. the melt flow based on melt state sensory perceptual system in mould according to claim 1 and freezing rate detection method, it is characterized in that: after described step C, be also provided with step e, described step e, it is specially:
Determine to solidify the end time according to the freezing rate in injection mold, and then obtain best cool time.
8. the melt flow based on melt state sensory perceptual system in mould according to claim 1 and freezing rate detection method, it is characterized in that: in described mould, melt state sensory perceptual system comprises point electrode capacitor sensor and state recognition system, described point electrode capacitor sensor comprises point electrode capacitor and capacitance measurement unit, one of described point electrode capacitor is very arranged on the point electrode (1) in the quiet mould of mould (7), another of described point electrode capacitor is very arranged on the metal electrode on mould dynamic model, described point electrode (1) is all connected with capacitance measurement unit with metal electrode, the output of described capacitance measurement unit is connected with the input of state recognition system.
9. the melt flow based on melt state sensory perceptual system in mould according to claim 8 and freezing rate detection method, it is characterized in that: described electrode capacitor sensor also comprises nested (3) and helical bolt (4), in described point electrode (1), the top of the shaft shoulder (6) coordinates with the locating hole of mould the location realizing upward direction, bottom the coordinating by nested (3) and helical bolt (4) of the shaft shoulder (6) in described point electrode (1), realization location in downward direction.
10. the melt flow based on melt state sensory perceptual system in mould according to claim 9 and freezing rate detection method, it is characterized in that: in described mould, melt state sensory perceptual system comprises point electrode capacitor sensor and state recognition system, described point electrode capacitor sensor comprises point electrode capacitor and capacitance measurement unit, one of described point electrode capacitor is very arranged on the point electrode (1) on mould dynamic model thimble, another of described point electrode capacitor is very arranged on the metal electrode on the quiet mould of mould (7), described point electrode (1) is all connected with capacitance measurement unit with metal electrode, the output of described capacitance measurement unit is connected with the input of state recognition system.
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