Quantitative mold quality inspection method and system based on cooperation of pressure sensing and intelligent vision

Abstract

The invention discloses a quantitative mold quality inspection method based on cooperation of pressure sensing and intelligent vision. The quantitative mold quality inspection method comprises a mold closing test module, a mold closing analysis module, an injection molding process state monitoring module, an injection molding process state analysis module, a product quality state monitoring module and a product quality state analysis module. The invention further discloses a mold quantitative quality inspection system based on cooperation of pressure sensing and intelligent vision. And comparing the arithmetic mean value and the variance of the monitored gap width and the position offset distance of the mold with the preset arithmetic mean value and variance. And judging whether the product is qualified or not by utilizing a pressure maintaining formula and a defect evaluation index formula.

Description

Technical Field

[0001] This invention relates to a quantitative quality inspection method and system for molds based on the collaboration of pressure sensing and intelligent vision, and particularly to its pressure holding step, belonging to the field of mold quality inspection technology. Background Technology

[0002] Injection molding is a highly efficient plastic molding process that involves injecting molten plastic into a mold cavity, where it cools to obtain a product conforming to the mold's shape. First, the plastic raw material is heated and melted into a fluid state. Then, high pressure forces the molten plastic into the cavity of a closed mold. Afterward, the plastic cools and solidifies within the cavity, and the mold is opened to remove the finished product. It allows for the mass production of plastic products, widely used in home appliances, automobiles, electronics, medical devices, and daily necessities, such as mobile phone casings, automotive parts, plastic tableware, and appliance casings. However, due to the complex shapes of injection-molded products, defects frequently occur during manufacturing if the mold design is inadequate, such as surface pits, shrinkage marks, and internal air bubbles. Therefore, how to conduct quality inspection of the mold and reduce the probability of defects in injection-molded products is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0003] To overcome the above-mentioned shortcomings, the purpose of this invention is to provide a quantitative quality inspection method and system for molds based on the collaboration of pressure sensing and intelligent vision, in order to determine whether the mold meets the quality inspection requirements.

[0004] To achieve the above objectives, the technical solution adopted by this invention is: a quantitative quality inspection method for molds based on the collaboration of pressure sensing and intelligent vision, comprising:

[0005] The mold closing test module is used to acquire mold closing data, including monitoring gap width and monitoring position offset distance;

[0006] The mold closing analysis module determines whether injection molding is allowed based on mold closing deviations.

[0007] The injection molding process status monitoring module is used to monitor the pressure monitoring points of the mold and obtain the pressure of the pressure monitoring points in real time.

[0008] The injection molding process status analysis module is used to analyze whether there are any abnormalities in the pressure.

[0009] The product quality status monitoring module is used to monitor the weight of the products, obtain the weight of each injection molded product, and simultaneously use a CCD device to acquire surface images of each injection molded product to analyze surface defects. It also uses light to illuminate each injection molded product to analyze whether there are air bubbles inside. If the projection is uneven, the product is considered unqualified; if the projection is uniform, the product is considered qualified.

[0010] The product quality status analysis module determines whether the injection molding process is qualified based on the weight, surface defects, and uniformity of transmitted light of the injection molded product.

[0011] The present invention is further configured such that: the mold closing deviation judgment refers to extracting the monitoring gap width and position offset distance of the mold, calculating the arithmetic mean and variance; then comparing it with the preset arithmetic mean and variance. If it is greater, the mold is re-closed; if it is less, the injection operation is performed. This process is repeated N times. If N≤1, the quality inspection is qualified; otherwise, it is unqualified.

[0012] The present invention is further configured as follows: before injection, the mold is filled with high-pressure gas to test its sealing performance; then the high-pressure gas is discharged, injection is performed, and a vacuum is drawn, which is maintained for 2 minutes; then pressure is applied during the cooling stage.

[0013] The pressure of the high-pressure gas inside the mold is denoted as PQ, and the pressure during the vacuuming stage is denoted as PZ. If the pressure holding formulas PQmax / PQmin > PQ1 and PZmax / PZmin > PZ1 are satisfied, the quality inspection is qualified; otherwise, the quality inspection is unqualified.

[0014] Where PQmax is the maximum value after high-pressure gas is introduced; PQmin is the minimum value after high-pressure gas is introduced; PQ1 is a preset constant; PZmax is the maximum pressure during the vacuuming stage; PZmin is the minimum pressure during the vacuuming stage; and PZ1 is another preset constant.

[0015] The present invention is further configured such that: the product quality status analysis module constructs a defect evaluation index formula for injection molded products, and the specific method is as follows:

[0016] Extract the weight and number of surface defects of each injection molded product, denoted as W and M, where n represents the number of injection molded products; the defect evaluation index formula is DI = [a×(W1÷W0+W2÷W0……+Wn÷W0) / n + b×(M1÷M0+M2÷M0……+Mn÷M0) / n] ÷ (a+b);

[0017] Where a is the weight of the number of defects, b is the weight of the product weight, M0 is the baseline number of defects (e.g., M0=2, meaning a qualified product is allowed a maximum of 2 defects), and W0 is the baseline weight, which can be the product's standard weight or design weight.

[0018] The defect evaluation index is compared with the pre-set defect evaluation index threshold for injection molded products; if it is less than the threshold, the mold quality inspection is deemed qualified; otherwise, the mold quality inspection is deemed unqualified.

[0019] This invention also provides a mold quantitative quality inspection system based on pressure sensing and intelligent vision collaboration, including a main pipe, a docking part, and a first valve. The first valve is located at the end of the main pipe, and the docking part is located at the outlet of the first valve. The mold has a gate, which is docked with the first valve. A second valve is located at the inlet of the main pipe. A first branch pipe and a second branch pipe are connected to the middle of the main pipe. A vacuum pump is connected to the end of the first branch pipe, and a third valve is located in the middle of the first branch pipe. A high-pressure gas tank is connected to the end of the second branch pipe, and a fourth valve is located in the middle of the second branch pipe.

[0020] Compared with existing technologies, the beneficial effects of this invention are as follows: The mold closing test module acquires and monitors the gap width and position offset distance; the injection molding process status monitoring module determines whether the mold closing is qualified, avoiding the formation of bulges and skewing in the gaps by the molten injection plastic. The mold closing analysis module determines whether injection molding is allowed based on the mold closing deviation; the injection molding process status analysis module determines whether it is qualified by analyzing the pressure changes inside the mold; the product quality status monitoring module acquires the weight of each injection molded product, and simultaneously uses a CCD device to collect surface images of each injection molded product to analyze surface defects; it also uses light to illuminate each injection molded product to analyze whether there are air bubbles inside; the product quality status analysis module determines whether the injection molding process is qualified based on the weight, surface defects, and uniformity of transmitted light. Molds that pass the tests produce injection molded products with fewer defects. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a mold quantitative quality inspection method based on the collaboration of pressure sensing and intelligent vision, according to a preferred embodiment of the present invention.

[0022] Figure 2 for Figure 1 A schematic diagram of a quantitative quality inspection method for molds based on the collaboration of pressure sensing and intelligent vision.

[0023] Figure 3 for Figure 1 A schematic diagram of the structure of a mold quantitative quality inspection system based on the collaboration of pressure sensing and intelligent vision.

[0024] In the diagram: 1. Mold; 2. Gate; 3. Joint; 4. First valve; 5. Third valve; 6. Fourth valve; 7. Second valve; 8. Vacuum pump; 9. High-pressure gas tank; 10. Main pipe; 11. First branch pipe; 12. Second branch pipe. Detailed Implementation

[0025] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0026] See appendix Figure 1-2 As shown, the mold quantitative quality inspection method based on pressure sensing and intelligent vision collaboration in this embodiment includes:

[0027] The mold closing test module is used to acquire mold closing data, including monitoring gap width and monitoring position offset distance;

[0028] The mold closing analysis module determines whether injection molding is allowed based on mold closing deviations.

[0029] The injection molding process status monitoring module is used to monitor the pressure monitoring points of the mold and obtain the pressure of the pressure monitoring points in real time.

[0030] The injection molding process status analysis module is used to analyze whether there are any abnormalities in the pressure.

[0031] The product quality status monitoring module is used to monitor the weight of the products, obtain the weight of each injection molded product, and simultaneously use a CCD device to acquire surface images of each injection molded product to analyze surface defects. It also uses light to illuminate each injection molded product to analyze whether there are air bubbles inside. If the projection is uneven, the product is considered unqualified; if the projection is uniform, the product is considered qualified.

[0032] The product quality status analysis module determines whether the injection molding process is qualified based on the weight, surface defects, and uniformity of transmitted light of the injection molded product.

[0033] The determination of mold closing deviation refers to extracting the monitoring gap width and position offset distance of the mold, calculating the arithmetic mean and variance; then comparing it with the preset arithmetic mean and variance. If it is greater, the mold is re-closed; if it is less, the injection operation is performed. This process is repeated N times. If N≤1, the quality inspection is qualified; otherwise, it is unqualified.

[0034] Before injection, the mold is filled with high-pressure gas to test its sealing performance; then the high-pressure gas is discharged, injection is performed, and a vacuum is drawn, which is maintained for 2 minutes; then, pressure is applied during the cooling stage; the pressure of the high-pressure gas inside the mold is denoted as PQ, and the pressure during the vacuum stage is denoted as PZ; if the pressure holding formulas PQmax / PQmin > PQ1 and PZmax / PZmin > PZ1 are satisfied, the quality inspection is qualified; otherwise, the quality inspection is unqualified; where PQmax is the maximum value after filling with high-pressure gas; PQmin is the minimum value after filling with high-pressure gas; PQ1 is a preset constant; PZmax is the maximum pressure during the vacuum stage; PZmin is the minimum pressure during the vacuum stage; and PZ1 is another preset constant.

[0035] The product quality status analysis module constructs a defect evaluation index formula for injection molded products, specifically as follows: Extract the weight and number of surface defects for each injection molded product, denoted as W and M, where n represents the number of injection molded products; the defect evaluation index formula is: DI = [a×(W1÷W0+W2÷W0……+Wn÷W0) / n + b×(M1÷M0+M2÷M0……+Mn÷M0) / n] ÷ (a+b); where a is the weight of the number of defects, b is the weight of the product weight, M0 is the baseline number of defects (e.g., M0=2, meaning a qualified product is allowed a maximum of 2 defects), and W0 is the baseline weight, which can be the product's standard weight or design weight.

[0036] The defect evaluation index is compared with the pre-set defect evaluation index threshold for injection molded products; if it is less than the threshold, the mold quality inspection is deemed qualified; otherwise, the mold quality inspection is deemed unqualified.

[0037] See Figure 3 As shown, the present invention also provides a mold quantitative quality inspection system based on pressure sensing and intelligent vision collaboration, including a main pipe 10, a docking part 3, and a first valve 4. The first valve 4 is located at the end of the main pipe 10, and the docking part 3 is located at the outlet of the first valve 4. The mold 1 has a gate 2, which is docked with the first valve 4. A second valve 7 is provided at the inlet of the main pipe 10. A first branch pipe 11 and a second branch pipe 12 are connected to the middle of the main pipe 10. A vacuum pump 8 is connected to the end of the first branch pipe 11, and a third valve 5 is provided in the middle. A high-pressure gas tank 9 is connected to the end of the second branch pipe 12, and a fourth valve 6 is provided in the middle.

[0038] High pressure is created inside the mold by opening the fourth valve 6. The airtightness of the mold is tested. Then, the fourth valve 6 is closed to release the high-pressure gas, and the first valve 4 and second valve 7 are opened to inject molten plastic into the mold. Then, the first valve 4 and second valve 7 are closed, and the third valve 5 is opened to create a vacuum inside the mold. Air bubbles inside the mold are expelled, and then the third valve 5 is closed. The first valve 4 and second valve 7 are then opened to continue injecting small amounts of molten plastic into the mold to maintain mold pressure and compensate for shrinkage caused by the solidification and shrinkage of the molten plastic during cooling.

[0039] In summary, the principle of the mold quantitative quality inspection method based on the collaboration of pressure sensing and intelligent vision shown in this invention is as follows: The mold closing test module obtains the monitored gap width and the monitored position offset distance; extracts the monitored gap width and position offset distance of the mold, and the mold closing analysis module determines whether the mold closing is qualified, calculates the arithmetic mean and variance; then compares them with the preset arithmetic mean and variance. If it is greater, it is judged that the mold cannot be accurately closed, there are gap and displacement deviations, and the mold needs to be closed again. Otherwise, bumps will be formed on the surface of the injection molded part and the injection molded part will be skewed. The injection process state analysis module analyzes the pressure change inside the mold. If the pressure holding formula PQmax / PQmin > PQ1 is satisfied, it is judged that the airtightness of the mold is good and there will be no leakage of molten injection liquid, and the mold closing reaches a better level. After vacuum pumping, the bubbles inside the injection liquid expand, become larger, and burst until they are discharged. If the formula PZmax / PZmin > PZ1 is satisfied, it means that there are few bubbles in the injection liquid in the mold, the gas inside the mold can be discharged during the injection process of the mold, and the mold design is reasonable. The product quality state monitoring module obtains the weight of each injection molded product, collects the surface images of each injection molded product through a CCD device, and analyzes the surface defects of the injection molded product; the product quality state analysis module compares the defect evaluation index with the preset injection molded product defect evaluation index threshold; if it is less, the weights of the injection molded parts are uniform, and it is judged that the mold quality inspection is qualified. On the contrary, there are defects such as bubbles, cavities, bumps, and sink marks inside the injection molded parts, and it is judged that the mold quality inspection is unqualified. Illuminating each injection molded product with light, the product quality state analysis module analyzes whether there are bubbles inside the injection molded product; if there are bubbles, it will cause the image formed by the light passing through the injection molded part to be uneven and divergent, etc., and it is judged as unqualified. If there are no bubbles, the image formed by the light passing through the injection molded part is uniform, and it is judged as qualified.

[0040] The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it. It cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. A quantitative quality inspection method for molds based on the collaboration of pressure sensing and intelligent vision, characterized in that, Including: A mold closing test module, which is used to obtain the mold closing data, including monitoring the gap width and the position offset distance; A mold closing analysis module, which judges whether the injection molding operation is allowed according to the mold closing deviation situation; An injection molding process state monitoring module, which is used to monitor the pressure monitoring points of the mold and obtain the pressure of the pressure monitoring points in real time; An injection molding process state analysis module, which is used to analyze whether there is any abnormality in the pressure; A product quality state monitoring module, which is used to monitor the weight of the product, obtain the weight of each injection molded product, and at the same time use a CCD device to collect the surface images of each injection molded product to analyze the surface defects of the injection molded product; illuminate each injection molded product with light to analyze whether there are bubbles inside the injection molded product. If the projection is uneven, the quality inspection is unqualified. If the projection is uniform, the quality inspection is qualified; A product quality state analysis module, which judges whether the production process of the injection molded product is qualified based on the weight, surface defects and light transmission uniformity of the injection molded product.

2. The quantitative quality inspection method for molds based on pressure sensing and intelligent vision collaboration as described in claim 1, characterized in that: The judgment of the mold closing deviation situation means extracting the monitored gap width and position offset distance of the mold, calculating the arithmetic mean and variance; and then comparing them with the preset arithmetic mean and variance. If it is greater, re-close the mold. If it is less, perform the injection operation; Loop N times like this; if N≤1, the quality inspection is qualified, otherwise it is unqualified.

3. The quantitative quality inspection method for molds based on the collaboration of pressure sensing and intelligent vision as described in claim 2, characterized in that: Before injecting the mold, first fill it with high-pressure gas to test the airtightness; then discharge the high-pressure gas, inject, and evacuate, and maintain it for 2 minutes in a vacuum state; then pressurize during the cooling stage; The pressure of the high-pressure gas in the mold is denoted as PQ, and the pressure in the evacuation stage is denoted as PZ; if the pressure holding formula PQmax / PQmin>PQ1 and PZmax / PZmin>PZ1 are satisfied, the quality inspection is qualified, otherwise the quality inspection is unqualified; Where PQmax is the maximum value after filling with high-pressure gas; PQmin is the minimum value after filling with high-pressure gas; PQ1 is a preset constant; PZmax is the maximum value of the pressure in the evacuation stage; PZmin is the minimum value of the pressure in the evacuation stage; PZ1 is another preset constant.

4. The quantitative quality inspection method for molds based on pressure sensing and intelligent vision collaboration as described in claim 3, characterized in that: The product quality state analysis module constructs a defect evaluation index formula for injection molded products, and the specific method is as follows: Extract the weight and the number of surface defects of each injection molded product, denoted as W and M, where n represents the number of injection molded products; the defect evaluation index formula DI = [a×(W1÷W0+W2÷W0……+Wn÷W0) / n + b×(M1÷M0+M2÷M0……+Mn÷M0) / n] ÷ (a+b); Among them, a is the weight of the number of defects, b is the weight of the product weight, M0 is the reference number of defects, such as M0 = 2, that is, the qualified product is allowed at most 2 defects. W0 is the reference weight, which can be the product standard weight or the design weight; Compare the defect evaluation index with the preset defect evaluation index threshold of the injection molded product; if it is less, judge that the mold quality inspection is qualified, otherwise, judge that the mold quality inspection is unqualified.

5. A mold quantitative quality inspection system based on pressure sensing and intelligent vision collaboration, comprising a main pipe, a docking part, and a first valve, wherein the first valve is located at the end of the main pipe, and the docking part is located at the outlet of the first valve; characterized in that, The mold has a gate that is connected to the first valve; a second valve is provided at the inlet of the main pipe; a first branch pipe and a second branch pipe are connected to the middle of the main pipe; a vacuum pump is connected to the end of the first branch pipe and a third valve is provided in the middle; a high-pressure gas tank is connected to the end of the second branch pipe and a fourth valve is provided in the middle.

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