CN110978441A

CN110978441A - Visual injection molding production process verification method

Info

Publication number: CN110978441A
Application number: CN201911060135.6A
Authority: CN
Inventors: 贺磊; 王怡; 尹广亮; 郑优生
Original assignee: Shanghai Pengrui Intelligent Technology Co Ltd
Current assignee: Shanghai Pengrui Intelligent Technology Co Ltd
Priority date: 2019-11-01
Filing date: 2019-11-01
Publication date: 2020-04-10

Abstract

The invention discloses a visual injection molding production process verification method, which comprises the following steps: s1) collecting product batch, injection molding machine state, plastic characteristic and mould characteristic data; s2) setting injection molding process parameters and corresponding production thresholds thereof; s3), monitoring the current process curve in real time in the injection molding process, comparing the current process curve with the standard process curve in the early-stage mold testing stage for verification, and judging as a defective product if the current process curve and the standard process curve do not accord with each other; s4) continuously verifying the external dimension parameters of the product passing the process curve verification, and judging the product as a good product if the external dimension meets the requirement. The invention can monitor and control the process curve formed in the production process, improve the consistency of injection products by controlling the process parameters, avoid the abnormality of the whole batch, simultaneously realize the complete separation of good and defective products and reduce the production cost of enterprises.

Description

Visual injection molding production process verification method

Technical Field

The invention relates to a production process verification method, in particular to a visual injection molding production process verification method.

Background

The traditional product process verification is realized by setting constant parameters, and then the mode of verifying the product appearance by hand or machine and the properties of stretching, folding, compression resistance, low temperature resistance and the like of the product are tested in a sampling mode. Practice proves that the method is not accurate enough, and on one hand, inferior-quality products with unsatisfactory appearance can be caused, and waste of materials, labor cost and time is caused; on the other hand, the appearance meets the requirements, but the performance of the actual plastic product cannot meet the standards, which brings great trouble to the product delivery team and the quality control department and also seriously affects the cost reduction and efficiency improvement of enterprises and brand creation.

Because the process guarantee technology of the traditional injection molding production only focuses on the constant setting of machine parameters, however, the time-varying property of the plastic product in the injection molding process is very strong, the working condition fluctuation of the injection molding process can be caused by slight interference of external environments such as production environment, production equipment, a mold, material properties and the like, the consistency of the product is further influenced, and the problems of difficult quality control, waste of production cost and the like can be caused due to the difficult detection and long feedback time of the subsequent product quality.

At present, modular flow analysis software is available on the market, products such as Moldflow, Moldex3D and the like can be well simulated, but the modular flow analysis software is mainly applied to forward design, and the actual production environment is influenced by multiple factors such as equipment machines, materials, factory environment and the like; therefore, the simulation environment and the actual production environment often have a large difference.

In addition, the source of the injection molding machine state data in the injection molding process is an injection molding machine table, the injection molding machine state data comprises data such as injection pressure, speed, time, pressure maintaining pressure and the like, but the data is subjected to transmission attenuation, and the pressure and temperature data at the product end can only be obtained through calculation to have large errors.

It can be seen from the above that, the production mode of setting for invariable machine parameter at present does not represent invariable production technology, and the actual performance of product can also appear the phenomenon that actual technology is not up to standard along with production environmental change etc. and the product of output, and subsequent manual or machine verification outward appearance, spot check product property ability, it is longer to consume time, and the accuracy is not high, and can cause the waste of manufacturing cost.

Disclosure of Invention

The invention aims to solve the technical problem of providing a visual injection production process verification method, which can monitor and control a process curve formed in the production process, improve the consistency of injection products by controlling process parameters, avoid the abnormality of the whole batch, simultaneously realize the complete separation of good and defective products and reduce the production cost of enterprises.

The technical scheme adopted by the invention for solving the technical problems is to provide a visual injection molding production process verification method, which comprises the following steps: s1) collecting product batch, injection molding machine state, plastic characteristic and mould characteristic data; s2) setting injection molding process parameters and corresponding production thresholds thereof; s3), monitoring the current process curve in real time in the injection molding process, comparing the current process curve with the standard process curve in the early-stage mold testing stage for verification, and judging as a defective product if the current process curve and the standard process curve do not accord with each other; s4) continuously verifying the external dimension parameters of the product passing the process curve verification, and judging the product as a good product if the external dimension meets the requirement.

In the visual injection molding production process verification method, the injection molding machine state data in the step S1 includes the pressure holding time and the pressure holding pressure, and the step S3 controls the current pressure holding time and pressure holding pressure to be consistent with the pressure holding time and pressure holding pressure in the previous mold testing stage.

The visual injection molding production process verification method comprises the following production threshold value obtaining steps in step S2: during early-stage mold testing, the acceptable upper limit appearance and size of the product are determined by adjusting the pressure maintaining pressure; taking 110% -120% of the lower limit cavity pressure and 90% of the upper limit cavity pressure as initial production thresholds.

In the visual injection molding production process verification method, the current process curve is monitored in real time in the step S3, and if the current process curve is within the threshold range and the relative error with the standard process curve is smaller than the preset error value; the product is judged to meet the production requirement, and the control connecting line outputs a 24V signal to the manipulator, and the product is sent to the subsequent step S4.

In the visual injection molding production process verification method, the injection molding machine state data in step S1 includes injection pressure and temperature, which are obtained by measuring the surface of the product by directly arranging a sensor in the mold cavity.

The visual injection molding production process verification method comprises the following steps of S1: s11) changing the mould into one mould with two cavities, each cavity being provided with a plurality of gates for feeding glue; s12) arranging a temperature and pressure integrated sensor at the end gate, and arranging pressure sensors at other gates; s13) feeding glue into the plurality of gates through a hot runner sequence valve; s14) during the pre-trial molding stage, simultaneously collecting the injection pressure and temperature data, and monitoring the warping condition of the product.

According to the visual injection molding production process verification method, when the length of an injection molding product in a mold is 800mm-1000mm, 5 gates are arranged in each cavity in the step S11 for glue feeding, temperature and pressure integrated sensors are symmetrically arranged on two sides of a tail end gate, and the step S14 records corresponding injection pressure and temperature data when the product warpage meets the requirement; and step S3, in the actual injection molding process, controlling the injection pressure and temperature data to be consistent with the recorded values in the early stage of mold trial.

The visual injection molding production process verification method comprises the steps that the surface of the temperature and pressure integrated sensor is provided with a wear-resistant coating, the pressure measurement range is 0-2000Bar, and the temperature measurement range is 0-450 ℃.

Compared with the prior art, the invention has the following beneficial effects: according to the visual injection molding production process verification method provided by the invention, the process curve formed in the production process is monitored and controlled, the consistency of injection molding products is improved by controlling process parameters, and then the accurate verification is carried out by checking the appearance size, so that the separation of good and defective products is realized in an automatic manner, the abnormity of the whole batch of products is avoided, the production cost loss is reduced, and the production process is more accurate.

Drawings

FIG. 1 is a flow chart of a visual injection molding production process verification method implementation of the present invention;

FIG. 2 is a schematic view of an embodiment of the present invention employing a multi-gate design;

FIG. 3 is a schematic view illustrating distribution of monitoring points according to an embodiment of the present invention;

FIGS. 4a and 4b are schematic diagrams illustrating variations of a manufacturing process according to an embodiment of the present invention;

FIG. 5 is a graph showing the pressure change at 3 points in actual production in the example of the present invention.

Detailed Description

The invention is further described below with reference to the figures and examples.

FIG. 1 is a flow chart of the visual injection molding production process verification method of the present invention.

Referring to fig. 1, the visual injection molding production process verification method provided by the invention includes the following steps:

and S1, collecting product batches, injection molding machine states, plastic characteristics and mold characteristic data, and realizing accumulation and precipitation of early-stage business data.

The data acquisition and analysis platform is used for acquiring production process information such as mold characteristics, plastic characteristics, injection molding machine states, product batches and the like, and standard process curves, process parameters and the like of an early-stage mold testing stage by means of a sensor, so that real-time analysis, follow-up tracing and the like of the total data volume are facilitated.

When the parameters are actually measured in the mold testing process, two products can be adopted as symmetrical products, 4 sensors are installed on each product, all corresponding sensors are set as the same group for comparison and monitoring, and meanwhile, the accuracy of the sensors is determined by taking the pressure in the mold flow analysis as comparison, so that the parameters can be corrected later and can be correctly input in the actual mold testing process.

Through the comparison of multiple sets of measured data, it can be found that:

1) under the condition that the mold flow analysis is consistent with the pressure maintaining pressure and pressure maintaining time setting in the actual mold test, the overall accuracy can reach about 78%.

In the mold flow analysis, as long as the accuracy of the material and the accuracy of the information of the injection molding machine are input and more accurate parameters are derived, the mold cavity pressure reflected in the CAE and the actual mold cavity pressure have higher accuracy. The data that CAE derived have higher accuracy and reference degree promptly, and the promotion of the degree of accuracy can reduce the accent quick-witted number of times of examination mould, very big promotion work efficiency with practice thrift the cost.

2) The appearance and the size of the product are improved by adjusting the pressure maintaining pressure. So that the quality of the product can meet the requirements of customers.

The comparison of the pressure confirms that under the condition of changing the holding pressure, the die cavity pressure in the die flow analysis and the actual pressure can be changed correspondingly, and the pressure pair and the accuracy at each position are also basically maintained at 78%. The mold cavity pressure to the CAE pressure is increased in a corresponding proportion, so that the feasibility of mold testing can be guided by the CAE pressure is relatively large.

3) From the change of the set pressure, when the pressure is increased after the change of the pressure is stable, whether the CAE or the actual pressure of the mold cavity changes correspondingly with the change of the set pressure, and the accuracy is relatively stable. The acceptable upper appearance and size of the good product is determined by adjusting the dwell pressure. So as to set corresponding threshold values as production monitoring.

And step S2, setting injection molding process parameters and corresponding production thresholds.

During production, although many parameters are fixed, it is necessary to monitor the actual pressure of the entire mold cavity as a quality criterion. According to the invention, the upper limit and the lower limit of the curve are automatically determined according to the requirement of the product quality, the upper limit and the lower limit are set as production thresholds, so that the production products are guaranteed to be good products within the threshold, and the good products and the defective products are separated. According to the invention, the production threshold value is accurately set, the curve range of good products is accurate, and the process consistency is ensured. The method comprises the following specific steps:

1) confirming the upper and lower limits of the appearance and the size of the product by adjusting the pressure maintaining pressure of the product;

2) the upper and lower limits of the size correspond to the upper and lower limits of the die cavity pressure;

3) the safety threshold is defined as follows: lower limit of pressure (actual lower limit of pressure) (1.1-1.2);

upper limit of pressure is 0.9 of actual upper limit of pressure;

in the present invention, 120% of the lower limit cavity pressure and 90% of the upper limit pressure are taken as threshold initial settings.

Setting the threshold value of the other curves according to the actual die cavity pressure of the corresponding period in the same way; along with the continuous increase of data volume and sample, the system can optimize and accurate threshold value scope automatically, makes production more intelligent, and the technology is more accurate.

And step S3, monitoring the current process curve in real time in the injection molding process, comparing the current process curve with the standard process curve in the early-stage mold testing stage for verification, and judging the product to be a defective product if the current process curve and the standard process curve do not accord with each other. The method comprises the following specific steps:

1) and (4) performing program setting on the manipulator, and setting a good-quality area and a defective area in the position.

2) After the production threshold is set, the system can judge the monitored curve, and the product which does not exceed the threshold is defined as a good product.

3) And comparing a real-time process curve generated in the production process with a standard process curve, and verifying whether the curve is in a threshold range through graphical analysis and data analysis.

4) And (3) curve verification process:

if the process curve is in the threshold range, the product is considered to meet the production requirement, the connecting line outputs a 24V signal to the mechanical arm, and the product is defined as a good product and continues to follow-up processes;

if the process curve exceeds the threshold range, the product is considered to be a defective product, the system does not transmit a signal to the manipulator, the manipulator judges the product which does not receive the signal to be a defective product, and simultaneously, after the signal is verified, the production is recorded in the system.

Step S4, appearance verification process: and continuously verifying the external dimension parameters of the product verified by the process curve, and judging the product to be good if the external dimension meets the requirements.

And (4) carrying out appearance dimension verification on the product of the good product sample, if the dimension meets the requirement, outputting a 24V signal to the manipulator through the connecting line, and outputting the product according to the good product.

If the size does not meet the requirement, the connecting line can not output signals to the mechanical arm, the good products of the samples are processed according to defective products, and meanwhile, the abnormity is recorded in the system, so that the threshold range is continuously optimized in the following process, and accurate production is realized.

The invention monitors and controls the process curve formed in the production process, improves the consistency of injection products by controlling the process parameters, avoids the abnormity of the whole batch in a process curve visual analysis and mechanical arm sorting mode, simultaneously realizes the complete separation of good products and defective products, ensures the hundred percent delivery of good products and reduces the production cost of enterprises.

For injection products with larger appearance sizes, how to solve the problem of warping is a well-known technical difficulty. The original injection molding production is mainly determined by the experience of a technician, and the solution of the warping problem can only be continuously tried and carried out in numerous enumerations. The invention can enable a craftsman to directly see the change form of a product in the forming process through a visualization technology, and solve the problem of warping deformation through the equal pressure ratio of two ends. Taking the production of the product of the refrigerator electroplated decorative strip as an example, the length is required to be 908 +/-0.2 mm, and the surface area is 925.099cm²Volume 73.9926cm³Due to the influences of factors such as the structural wall thickness, the flow and the cooling speed of the product, the biggest problem in the actual production of the product is buckling deformation, wherein the deformation in the X direction is 3.9mm, the deformation in the Y direction is 8.6mm, and the deformation in the Z direction is 2.7 mm. In order to solve the problem of warping and ensure the consistency of the produced products, the invention further carries out the following improvement treatment:

1. consider the flow constriction instead as a multi-gate design.

The mold is changed into one mold with two cavities, 5 points of glue are fed into each cavity in a hidden mode, the hot runner rotates to the cold runner, the sequence valve controls the gates, and the multi-gate design distribution is shown in figure 2.

2. And installing monitoring points, and monitoring the pressure and temperature change of the far gate at two ends.

Please refer to fig. 3: the product is a five-point hot runner sequence valve glue inlet, and 2 hot runner sequence valves are arranged

Warm-pressure integrated sensors (#1 and # 6); 4 are provided with

Pressure sensors (#2, #3, #4, # 5). The invention adopts the direct sensor in the die cavity to measure on the surface of the product, thereby greatly improving the accuracy.

1) The sensor is arranged near the glue inlet point, and the sensor has the advantages that:

the two positions are the positions of the gates which are opened firstly, and the whole forming process can be monitored by installing a pressure sensor. The more information displayed by injection molding is, the more process parameter adjustment is facilitated.

2) Filling a tail end warm pressing integrated sensor: 4mm direct type temperature and pressure integrated sensors are selected for symmetrical positions #1 and #6 at two sides of the tail end, and the advantages are as follows.

a. The filling tail end is far away from the pouring gate, so that the defects of product deformation, short shot, shrinkage and the like are more involved, and the pressure and temperature information needs to be collected simultaneously to analyze and solve the practical problem and improve the warping;

b. the space at the tail end of the process is limited, and two sensors are inconvenient to install at the same time, so that the pressure and the temperature at the same position of the tail end need to be monitored, the space of a die and the processing cost of the die are saved, and the installation of a temperature and pressure integrated sensor is the best choice;

c. the temperature and pressure integrated sensor uses a wear-resistant high-temperature-resistant insulating wire sheath, and the surface of the sensor is provided with a wear-resistant coating; the pressure measuring range is 0-2000Bar, and the temperature measuring range is 0-450 ℃;

the purpose is as follows: the product is an appearance piece, the appearance and deformation requirements are high, and the temperature and pressure integrated monitoring and visualization are adopted, so that the pressure distribution and temperature of the product can be effectively adjusted, and the quality, size, appearance, deformation and the like of the product are optimized.

3. And analyzing and adjusting the optimal process by the test model data. The high-precision sensor is used for collecting the production process information such as the characteristics of the mold, the characteristics of plastics, the state of the injection molding machine, the batch of products and the like, so that the forming process is visualized, and the pressure and temperature change forms a corresponding curve. As can be seen from fig. 4a, the difference between the far gate pressure peaks is large, and the pressure variation in the pressure holding stage is unstable, and by adjusting the process, as can be seen from fig. 4b, the peak pressure imbalance is reduced, and the warpage deformation is reduced.

4. And drawing the acquired sensor data into a forming process curve through a data acquisition and analysis platform, and comparing the actual production data with the simulation data. The pressure change curve at 3 points in actual production is shown in fig. 5. By comparing the measured data with the simulation data, it can be found that:

1) the near-gate simulation pressure 465Bar, the filling time is 3.48 seconds, the actual production near-gate pressure is 460Bar, the filling time is 1.9 seconds, and the filling time difference is large;

2) parameters such as mold temperature (50 ℃ adjusted to 60 ℃), injection time (2.5s adjusted to 1.5s), and holding pressure (50Mpa adjusted to 60 Mps) were corrected, and secondary simulation was performed by substituting actual parameters after mold testing.

3) The secondary simulation result shows that the warping quantity Y direction is 5.8mm, and the method is improved compared with the primary process. By correcting the boundary conditions, the CAE simulation result is closer to the real pressure. In the die flow analysis, the die cavity pressure reflected in the CAE has a certain difference with the actual die cavity pressure, but under the same process, the shapes of pressure and temperature change curves in the product forming process are similar, and the actual production environment factors are used as correction conditions, so that data obtained by the CAE based on basic simulation has higher accuracy and reference, the working efficiency can be greatly improved, the cost can be saved, and the specific problems can be correspondingly improved. Preferably, the temperature of the control mold is 50-60 ℃, the gate rubber injection time is 2.5-1.5 s, the pressure maintaining pressure in the cavity at the front gate is 30MPa, the pressure maintaining time is 1.5s, the pressure maintaining pressure in the cavity at the rear gate is 55-60 MPa, and the pressure maintaining time is 8.5 s.

The pressure at the two ends of the product tends to be close by adjusting the process curves at the two ends of the product, the stability of the pressure maintaining stage is improved by the pressure maintaining pressure and the mold temperature, the warping problem of the product can be improved, and the quality of the product can meet the requirements of customers. From the change of the set pressure, when the pressure is increased after the change of the pressure is stable, whether the CAE or the actual pressure of the mold cavity changes correspondingly with the change of the set pressure, and the accuracy is relatively stable. The acceptable upper appearance and size of the good product is determined by adjusting the dwell pressure.

5. Locking process

And trying to find out the optimal process to obtain the optimal product through multiple die testing and simulation, and trying to find out the corresponding curve variation range of the qualified product on the basis of the optimal process to obtain the threshold data required to be set. Although many parameters are fixed during the production process, the actual pressure of the entire mold cavity needs to be monitored as a quality criterion. The invention can automatically measure the upper limit and the lower limit of the curve according to the requirement of the product quality, and set the upper limit and the lower limit as the production threshold, thereby ensuring that the produced products are all good products within the threshold and separating the good products from the defective products.

Although the present invention has been described with respect to the preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A visual injection molding production process verification method is characterized by comprising the following steps:

s1) collecting product batch, injection molding machine state, plastic characteristic and mould characteristic data;

s2) setting injection molding process parameters and corresponding production thresholds thereof;

s3), monitoring the current process curve in real time in the injection molding process, comparing the current process curve with the standard process curve in the early-stage mold testing stage for verification, and judging as a defective product if the current process curve and the standard process curve do not accord with each other;

s4) continuously verifying the external dimension parameters of the product passing the process curve verification, and judging the product as a good product if the external dimension meets the requirement.

2. The visual injection molding production process verification method of claim 1, wherein the injection molding machine state data in step S1 includes a dwell time and a dwell pressure, and the step S3 controls the current dwell time and the dwell pressure to be consistent with the dwell time and the dwell pressure in the previous mold trial stage.

3. The visual injection molding production process verification method of claim 2, wherein the production threshold obtaining step in step S2 is as follows:

during early-stage mold testing, the acceptable upper limit appearance and size of the product are determined by adjusting the pressure maintaining pressure;

taking 110% -120% of the lower limit cavity pressure and 90% of the upper limit cavity pressure as initial production thresholds.

4. The visual injection molding production process verification method of claim 1, wherein in step S3, the current process curve is monitored in real time, and if the current process curve is within the threshold range and the relative error with the standard process curve is smaller than the preset error value; the product is judged to meet the production requirement, and the control connecting line outputs a 24V signal to the manipulator, and the product is sent to the subsequent step S4.

5. The visual injection molding production process verification method of claim 1, wherein the injection molding machine state data of step S1 includes injection pressure and temperature, which are obtained by measuring the surface of the product by directly arranging a sensor in the mold cavity.

6. The visual injection molding production process verification method of claim 5, wherein the step S1 further comprises:

s11) changing the mould into one mould with two cavities, each cavity being provided with a plurality of gates for feeding glue;

s12) arranging a temperature and pressure integrated sensor at the end gate, and arranging pressure sensors at other gates;

s13) feeding glue into the plurality of gates through a hot runner sequence valve;

s14) during the pre-trial molding stage, controlling the injection pressure and temperature data and monitoring the warping condition of the product.

7. The visual injection molding production process verification method of claim 6, wherein when the length of the injection molded product in the mold is 800mm-1000mm, 5 gates are arranged in each cavity in the step S11, temperature and pressure integrated sensors are symmetrically arranged on two sides of a terminal gate, and the step S14 records the corresponding injection pressure and temperature data when the product warpage meets the requirement; and step S3, in the actual injection molding process, controlling the injection pressure and temperature data to be consistent with the recorded values in the early stage of mold trial.

8. The visual injection molding production process verification method of claim 7, wherein the surface of the temperature and pressure integrated sensor is provided with a wear-resistant coating, the pressure measurement range is 0-2000Bar, and the temperature measurement range is 0-450 ℃.

9. The visual injection molding process verification method of claim 7, wherein the step S14 controls the mold temperature to be 50 ℃ to 60 ℃, the gate glue injection time to be 2.5S to 1.5S, the pressure holding pressure in the cavity at the front gate to be 30Mpa, the pressure holding time to be 1.5S, the pressure holding pressure in the cavity at the back gate to be 55Mpa to 60Mpa, and the pressure holding time to be 8.5S.