Leak detection solution for vacuum forming mold and leak point testing method

Abstract

The present application relates to a kind of leak detection glue for vacuum forming mold and leak point testing method, leak detection glue includes by mass fraction: 100 parts of water, 4.5-5.5 parts of polyvinyl alcohol, 30-40 parts of ethanol aqueous solution, 2-8 parts of glycerol, 0.1-0.2 parts of tributyl phosphate and 1-2 parts of water-based color paste;Leak point testing method is sealed after using vacuum bag film etc. on the surface of mold, and flow is led, let leak detection glue flow at suitable flow rate on the surface of mold and leak detection, mold is converted from air tightness test to liquid seal test, when there is leak point, continuous bubble can be directly observed to continuously emerge at leak point, and leak point is quickly judged;Meanwhile, by gradually feeding and discharging and reverse feeding and discharging and other operation modes, the interference of a leak point on subsequent leak point detection can be avoided.The viscosity of the leak detection glue of the present application is moderate, when vacuum flow is guided, it can be better guided, and it will not be too fast to cause difficulty in observation, it can be suitable for vacuum flow leak detection, and when exposed to air, it can quickly form a glue film, which can be directly torn off, and the operation efficiency is high.

Description

Technical Field

[0001] This invention belongs to the field of vacuum forming technology, specifically relating to a leak detection adhesive for vacuum forming molds and a leak detection method. Background Technology

[0002] Vacuum forming technology is widely used and its technology is becoming increasingly mature. Apart from process design, poor mold sealing and local leakage are currently one of the biggest sources of risk for this technology.

[0003] Especially when there are leaks in the molds of large, irregularly shaped, and complex structural components, it is impossible to plug and repair the leak without identifying its exact location. This would prevent vacuum forming production from proceeding and could lead to the complete scrapping of the mold, resulting in irreparable losses in cost and time. However, by accurately locating the leak, sealing and repair are possible. Therefore, the method of quickly detecting leaks in vacuum forming molds is extremely important.

[0004] In existing technologies, a vacuum bag and sealing strip are typically used to seal the mold, followed by vacuuming. The presence of pressure drop is then used to determine if leakage is present. However, even with a dedicated vacuum leak detector, it's impossible to pinpoint the exact location of a tiny leak when leakage is detected. The only solution is to repeatedly test by dividing the area into multiple zones. This time-consuming process, while narrowing down the leak area, doesn't directly pinpoint its location. Furthermore, since the vacuum bag itself may have ruptures and leaks, misjudgments can occur during the gradual narrowing of the leak detection area. This results in significant uncertainty and difficulty in leak detection for large products and in finding tiny leaks. Summary of the Invention

[0005] The technical problem this invention aims to solve is to address the shortcomings of the existing technology by providing a leak-detecting adhesive for vacuum forming molds and a leak detection method. The leak-detecting adhesive is prepared to a certain viscosity, sealed on the mold surface using a vacuum bag or similar material, and then guided to flow at a suitable rate across the mold surface for leak detection. This transforms the mold's airtightness testing into a liquid tightness testing. When a leak is detected, continuous bubbles can be visually observed emerging from the leak point, allowing for rapid identification. Furthermore, through step-by-step feeding and reverse feeding / discharging operations, interference from a single leak point on subsequent leak detections can be avoided. The leak-detecting adhesive is primarily composed of water, resulting in low cost. When exposed to air, it quickly forms a film that can be easily peeled off, leading to high operational efficiency and simplicity.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0007] A leak detection adhesive for a vacuum forming mold, the leak detection adhesive comprising, by weight: 100 parts water, 4.5-5.5 parts polyvinyl alcohol, 30-40 parts aqueous ethanol solution, 2-8 parts glycerin, 0.1-0.2 parts tributyl phosphate, and 1-2 parts water-based colorant.

[0008] In the above scheme, the molecular weight of the polyvinyl alcohol is 50,000-120,000 g / mol.

[0009] In the above scheme, the ethanol concentration in the aqueous ethanol solution is 90%-96%.

[0010] In the above scheme, the water-based pigment paste comprises, by weight, 30-50 parts water-based resin, 15-30 parts organic pigment, 20-40 parts water, 1-3 parts thickener and 3-6 parts dispersant.

[0011] In the above scheme, the aqueous resin is an acrylic emulsion; the organic pigment is zinc titanium red, phthalocyanine blue, or iron oxide yellow; the thickener is a carbamate; and the dispersant is sodium lignin xanthate.

[0012] In the above scheme, the leak detection adhesive is prepared by the following method:

[0013] When 100 parts of water are heated to above 90°C, add 4.5-5.5 parts of polyvinyl alcohol and stir continuously until completely dissolved.

[0014] Let stand and cool naturally to 70℃-78℃, then slowly add 30-40 parts of ethanol aqueous solution while continuously stirring at a speed of 500-1000r / min;

[0015] Then add 2-8 parts glycerol, 1-2 parts water-based pigment and 0.1-0.2 parts tributyl phosphate in sequence, and stir to disperse evenly.

[0016] Accordingly, the present invention also proposes a method for leak inspection of molds used in vacuum forming, comprising the following steps:

[0017] S1. Prepare the above-mentioned leak detection adhesive in advance and perform defoaming treatment;

[0018] S2. On the surface of the mold, lay a layer of guide net, cover the surface of the guide net with vacuum bag film, seal the vacuum bag film with sealing putty, and install the original feed pipe and the original discharge pipe at both ends of the vacuum bag film respectively. Then install several relay feed pipes between the original feed pipe and the original discharge pipe.

[0019] S3. Connect the original discharge pipe to the negative pressure device and draw in a negative pressure of -0.1 to -0.08 MPa. Clamp all subsequent feed pipes. Draw in leak detection adhesive from the original feed pipe end. After the adhesive has soaked and flowed beyond the first subsequent feed pipe, check for mold leakage points in the area between the original feed pipe and the first subsequent feed pipe. If no leakage points are found, continue feeding material from the original feed pipe and check the next area. If a significant mold leakage point is found, implement leak detection measures. The leak detection adhesive is then introduced from the next feed pipe after the leak point, and the original feed pipe end is changed to the discharge pipe end. In this way, the leak detection adhesive enters from the first feed pipe and flows towards the original feed pipe end and the original discharge pipe end respectively. On the one hand, the air bubbles formed between the original feed pipe end and the first feed pipe end will be drawn to the original feed pipe end, avoiding interference with the leak detection of the next section. On the other hand, the leak detection adhesive continues to soak towards the original discharge pipe end, continuing to test the sealing performance of the mold in the next section.

[0020] S4. Continue in this manner until all interval leak detections are completed.

[0021] In the above method, in step S1, the degassing treatment method is as follows: using a vacuum degassing device, the leak detection adhesive is degassed for 3-5 minutes at -0.098 to -0.1 MPa to eliminate its bubbles and set aside for later use, so as to avoid the small bubbles in the leak detection adhesive interfering with subsequent testing.

[0022] In the above method, the original feed pipe, the original discharge pipe, and the relay feed pipe are arranged in parallel with a span of 600-1000mm; a T-joint is installed in the middle of the original feed pipe, the original discharge pipe, and the relay feed pipe.

[0023] In the above method, in step S3, the basis for judging the mold leakage point is: when bubbles continuously rise from the bottom, the source of the rising bubbles is the mold leakage point; the method for marking the leakage point is: use a marker to draw a circle on the corresponding position on the surface of the vacuum bag film.

[0024] The beneficial effects of this invention are as follows:

[0025] 1. The leak detection adhesive of the present invention has the following advantages:

[0026] 1) At room temperature, the viscosity is approximately 100-500 mPa·s, which is moderate. During vacuum flow, it can conduct flow well without being too fast to make it difficult to observe, making it suitable for vacuum flow leak detection. The addition of polyvinyl alcohol allows the adhesive to cure into a film quickly under room temperature and exposed conditions. After film formation, it can be directly peeled off, resulting in high operational efficiency and convenient cleaning. The ethanol-water solution promotes the evaporation of the adhesive and accelerates the film formation rate. The addition of glycerol, by adjusting the proportion, can further thicken and adjust the viscosity, and improve the film quality of the adhesive. Tributyl phosphate has the effect of accelerating the elimination of air bubbles. The addition of water-based colorant gives the adhesive a distinct color, making the flow state of the adhesive more obvious, which can improve the detection and judgment of leaks.

[0027] 2) Water is the main raw material, and it is inexpensive;

[0028] 3) All ingredients are non-toxic, environmentally friendly, and easy to clean;

[0029] 4) The main components of the removed film material are polyvinyl alcohol, glycerin, and color paste. It can be reused. The collected film can be dissolved in water and mixed with various additives. It is reusable, reduces costs, is environmentally friendly, and is non-toxic.

[0030] 2. The leak detection method of the present invention has the following advantages:

[0031] This method involves sealing the aforementioned leak-detecting adhesive on the mold surface using a vacuum bag or similar material, then guiding it to flow at a suitable rate across the mold surface to detect leaks. This transforms the mold's airtightness test into a liquid tightness test. When a leak is detected, continuous bubbles can be visually observed emerging from the leak point, allowing for rapid and accurate identification of the leak. Furthermore, by employing step-by-step feeding and unloading methods, as well as reverse feeding and unloading, the method avoids interference from bubbles formed at the initial leak point on subsequent leak detection. Attached Figure Description

[0032] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0033] Figure 1 This is a schematic diagram of the interlayer during the leak inspection of the vacuum forming mold of the present invention.

[0034] Figure 2-4 This is a diagram illustrating the process of inspecting leaks in region 1 using the leak inspection method for the vacuum forming mold of the present invention.

[0035] Figure 5 This is a schematic diagram of the vacuum forming mold used in an embodiment of the present invention.

[0036] In the diagram: 1. Mold; 2. Guide net; 3. Vacuum bag film; 4. Sealing putty; 5. Original feed pipe; 6. Original discharge pipe; 7. Relay feed pipe; 71. First relay feed pipe; 72. Second relay feed pipe; 73. nth relay feed pipe; 8. Leak detection adhesive. Detailed Implementation

[0037] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0038] This invention proposes a leak detection adhesive for vacuum forming molds, comprising, by weight: 100 parts water, 4.5-5.5 parts polyvinyl alcohol, 30-40 parts aqueous ethanol solution, 2-8 parts glycerol, 0.1-0.2 parts tributyl phosphate, and 1-2 parts water-based colorant.

[0039] Further optimization resulted in the polyvinyl alcohol having a molecular weight of 50,000-120,000 g / mol.

[0040] Further optimization involves using an ethanol-water solution with an ethanol concentration of 90%-96%.

[0041] Further optimization is made to include, by weight, 30-50 parts of water-based resin, 15-30 parts of organic pigment, 20-40 parts of water, 1-3 parts of thickener, and 3-6 parts of dispersant.

[0042] Further optimization involves using an acrylic emulsion as the water-based resin; zinc titanium red, phthalocyanine blue, or iron oxide yellow as the organic pigment; a carbamate as the thickener; and sodium lignin xanthate as the dispersant.

[0043] The present invention also provides a method for leak inspection of molds used in vacuum forming, the specific implementation steps of which are as follows:

[0044] 1) Prepare the above leak detection adhesive in advance and use a vacuum degassing device to degas it for 3-5 minutes at -0.1 to -0.098 MPa to eliminate air bubbles before use, so as to avoid small air bubbles in the adhesive from interfering with subsequent testing.

[0045] 2) such as Figure 1As shown, a layer of guide net 2 is laid on the surface of mold 1, and a vacuum bag film 3 is laid on the surface of guide net 2. The vacuum bag film 3 is sealed around its perimeter with sealing putty 4. The original feed pipe 5 and the original discharge pipe 6 are installed at both ends of the vacuum bag film 3, respectively. Then, several relay feed pipes 7 are installed between the original feed pipe 5 and the original discharge pipe 6. The original feed pipe 5, the original discharge pipe 6, and the relay feed pipes 7 are arranged in parallel with a span of 600-1000mm. A T-joint is installed in the middle of the original feed pipe 5, the original discharge pipe 6, and the relay feed pipes 7. One end of the T-joint is used for feeding or connecting to the vacuum pump for discharge, and the other two ends are connected to spiral tubes inside the vacuum bag film for flow guidance.

[0046] 3) A vacuum is drawn at point 6 of the original discharge pipe. The first relay feed pipe 71, the second relay feed pipe 72, and the nth relay feed pipe 73 are clamped together. Leak detection adhesive 8 is drawn into point 5 of the original feed pipe. Leak detection adhesive 8 continuously enters from the end of the original feed pipe 5. Figure 2 As shown, area 1 is infiltrated, and leakage points are checked in area 1.

[0047] 4) If no continuous source of leakage bubbles is found in area 1, it proves that the leak detection in area 1 is qualified. Let the leak detection adhesive continue to soak into area 2 and continue the leak detection.

[0048] 5) If a continuous source of leakage bubbles is found in area 1, with small bubbles constantly rising from the bottom, the source of these rising bubbles is the leakage point of the mold. Figure 3 As shown, mark the location. After all leak detection in area 1 is completed, make the following process adjustments to the pipeline: a) Change the original feed pipe end 5 to the discharge pipe end. First, clamp the original feed pipe end 5, clean the adhesive at the end of the pipe, then connect the vacuum pump and draw negative pressure to switch to the discharge pipe; b) Enter the leak detection adhesive at the first relay feed pipe 71, and open the vacuum pump valve at the original feed pipe end 5 to switch to discharge. In this way, the leak detection adhesive enters from the first relay feed pipe 71 and flows towards the original feed pipe end 5 and the original discharge pipe end 6 respectively. The air bubbles formed at the leak point in area 1 will flow back towards the original feed pipe end 5 and will not flow into area 2 to interfere with the leak detection. At the same time, re-confirm the leak detection in the area directly behind the leak point in area 1; at the same time, the leak detection adhesive continues to soak towards the original discharge pipe end 6 and continues the leak detection in the next area, such as... Figure 4 As shown.

[0049] 6) The leak detection method for Zone 2 and subsequent zones is the same as that for Zone 1. If Zone 2 passes the inspection, continue soaking until Zone 3 for leak detection. If a leak is found in Zone 2, mark it, clamp the first relay feed pipe 71, and switch to feeding from the second relay feed pipe 72. The leak detection adhesive in Zone 2 flows in the opposite direction to the original feed pipe 5 to avoid air bubbles affecting subsequent zones. At the same time, the leak detection adhesive in Zone 3 continues to soak towards the original discharge pipe 6, and the leak detection continues in the next zone.

[0050] 7) Continue in this manner until leak detection is completed in all areas.

[0051] Table 1 provides four types of leak detection adhesives, all of which are prepared at room temperature.

[0052] Table 1

[0053]

[0054] Example 1:

[0055] A leak-detecting adhesive for vacuum forming molds is prepared as follows:

[0056] 1) Weigh the following raw materials by weight: 100 parts water, 5 parts polyvinyl alcohol, 35 parts ethanol aqueous solution, 5 parts glycerol, 0.15 parts tributyl phosphate and 1.5 parts water-based color paste.

[0057] The above-mentioned water-based color paste is made from the following raw materials by weight: 40 parts water-based resin, 20 parts organic pigment, 30 parts water, 2 parts thickener and 4.5 parts dispersant; the water-based resin is acrylic emulsion, the organic pigment is zinc titanium red, the thickener is urethane, and the dispersant is sodium lignin xanthate.

[0058] 2) When 100 parts of water are heated to above 90°C, add 5 parts of polyvinyl alcohol and stir to dissolve; let stand and cool naturally to 75°C, slowly add 35 parts of ethanol aqueous solution and stir vigorously at 700 r / min; then add 5 parts of glycerol, 1.5 parts of water-based pigment and 0.15 parts of tributyl phosphate in sequence, mix all components evenly, and degas the glue solution at -0.1 to -0.098 MPa for 5 minutes to eliminate bubbles before use.

[0059] The leak detection adhesive prepared in this embodiment was sampled and tested according to the standard GB / T 2794-2022 "Determination of viscosity of adhesives". The viscosity was measured to be 225 mPa·s at room temperature.

[0060] Select a 3000×1000×10mm vacuum forming mold, and prefabricate 4 pieces in a 2800×800mm area at the center of the mold. A 0.2mm defect was found; the location of the defect is shown in the image. Figure 5 Leakage tests were conducted at room temperature. The 2800×800mm area in the center of the mold was sealed with vacuum bags, sealing putty, etc., and a relay feed pipe was arranged every 700mm.

[0061] According to the mold leak inspection method, the adhesive prepared in Example 1 was used to inspect the 2800×800mm area in the center of the mold for leaks. The results are as follows: 1) The inspection time for all areas was 243s; 2) The adhesive flow rate was moderate; 3) Bubbles could be clearly observed to emerge steadily and continuously at the leak points, and the leak inspection was accurate and clear; 4) All four leak points were accurately detected, with a leak detection rate of 100%; 5) After removing the vacuum bag film and the guide net, the adhesive formed a film in 106 minutes; 6) The adhesive film was easy to clean after formation; 7) The adhesive film material can be recycled and reused.

[0062] Comparative Example 1:

[0063] A type of adhesive solution, the preparation method of which differs from that of Example 1, is that polyvinyl alcohol and glycerin are not added, while the other preparation conditions are the same as those of Example 1.

[0064] The adhesive prepared in Comparative Example 1 was sampled and tested according to the standard GB / T 2794-2022 Determination of Viscosity of Adhesives. The viscosity was measured to be 3 mPa·s at room temperature.

[0065] The location, size, and quantity of leak points in the pre-made mold are the same as in Example 1. The leak detection temperature, vacuum bag film application, and relay feed pipe location are also the same as in Example 1.

[0066] According to the mold leak inspection method, the adhesive prepared in Comparative Example 1 was used to inspect the 2800×800mm area in the center of the mold for leaks. Inspection results: 1) The inspection time for all areas was 35s; 2) The adhesive flow rate was too fast, and the adhesive quickly flowed to the original discharge end, making it impossible to change the original feed pipe to the discharge pipe in time; 3) The location of the first leak could be roughly seen, but the air bubbles formed by the first leak affected the observation of the specific location of subsequent leaks; re-inspection after changing the position of the original feed and discharge pipes also resulted in poor observation results due to a large number of residual air bubbles; 4) Only the approximate location of the first leak could be detected, and the judgment of subsequent leaks was interfered with, with a leak detection rate of 25%; 5) The adhesive did not form a film after removing the vacuum bag film and the guide net; 6) The adhesive needs to be thoroughly cleaned, and the cleaning and drying work is labor-intensive and time-consuming; 7) The material cannot be recycled and reused.

[0067] Comparative Example 2:

[0068] A type of adhesive solution, which differs from Example 1 in that: no tributyl phosphate is added, no vacuum degassing is performed on the adhesive solution, and all other preparation conditions are the same as in Example 1.

[0069] According to the standard GB / T 2794-2022 "Determination of viscosity of adhesives", the leak detection adhesive prepared in Comparative Example 4 was sampled and tested, and the viscosity was measured to be 235 mPa·s at room temperature.

[0070] The location, size, and quantity of leak points in the pre-made mold are the same as in Example 1. The leak detection temperature, vacuum bag film application, and relay feed pipe location are also the same as in Example 1.

[0071] According to the mold leak inspection method, the adhesive prepared in Comparative Example 2 was used to inspect the 2800×800mm area in the center of the mold for leaks. Inspection results: 1) The inspection time for all areas was 257s; 2) The adhesive flow rate was moderate; 3) Bubbles were observed to emerge steadily and continuously at the leak points, but irregular and continuous bubbles were mixed in the adhesive, which interfered with leak location and judgment; 4) All four leak points were detected, with a 100% detection rate; 5) After removing the vacuum bag film and the guide net, the adhesive formed a film in 108 minutes; 6) The adhesive film was easy to clean after formation; 7) The adhesive film material can be recycled and reused.

[0072] Comparative Example 3:

[0073] A solution of adhesive, which differs from Example 1 in that it does not contain an aqueous ethanol solution, but all other preparation conditions are the same as in Example 1.

[0074] The leak detection adhesive prepared in Comparative Example 5 was sampled and tested according to the standard GB / T 2794-2022 Determination of Viscosity of Adhesives. The viscosity was measured to be 310 mPa·s at room temperature.

[0075] The location, size, and quantity of leak points in the pre-made mold are the same as in Example 1. The leak detection temperature, vacuum bag film application, and relay feed pipe location are also the same as in Example 1.

[0076] According to the mold leak inspection method, the adhesive prepared in Comparative Example 3 was used to inspect the 2800×800mm area in the center of the mold for leaks. Inspection results: 1) The inspection time for all areas was 326s; 2) The adhesive flow rate was moderate; 3) Bubbles were observed to emerge steadily and continuously at the leak points; 4) All four leak points were detected, with a 100% detection rate; 5) After removing the vacuum bag film and the guide net, the adhesive formed a film in 273 minutes, which was relatively slow; 6) The adhesive film was easy to clean after formation; 7) The adhesive film material could be recycled and reused.

[0077] The performance test results of the leak detection adhesive prepared in Example 1 and Comparative Examples 1-3 of this invention at room temperature are shown in Table 2.

[0078] Table 2

[0079]

[0080] As can be seen from the comparison in Table 2, Example 1 has a higher detection rate. Leaks as small as 0.2 mm were all detected, with the inspection of all areas completed in 243 seconds and the adhesive film-forming time in 106 minutes. The adhesive film was easy to clean and recyclable. Comparative Example 1, without the addition of polyvinyl alcohol and glycerin, resulted in an excessively low adhesive viscosity and a high flow rate, making leak detection difficult. The adhesive also failed to form a film, was difficult to clean, and could not be recycled. Comparative Example 2, without the addition of tributyl phosphate and without vacuum degassing, detected all leaks. The adhesive film-forming time was similar to Example 1, and the adhesive film formed well, was easy to clean, and recyclable. However, air bubbles in the adhesive interfered with leak detection and assessment. Comparative Example 3, without the addition of an ethanol-water solution, detected all leaks. The adhesive film formed well, was easy to clean, and could be recycled. However, the excessively long film-forming time reduced leak detection efficiency.

[0081] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0082] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A leak-detecting adhesive for a vacuum forming mold, characterized in that, The leak detection adhesive comprises, by weight, 100 parts water, 4.5-5.5 parts polyvinyl alcohol, 30-40 parts aqueous ethanol solution, 2-8 parts glycerin, 0.1-0.2 parts tributyl phosphate, and 1-2 parts water-based colorant. The polyvinyl alcohol has a molecular weight of 50,000-120,000 g / mol; the ethanol concentration in the aqueous ethanol solution is 90%-96%; the aqueous color paste comprises, by weight, 30-50 parts of aqueous resin, 15-30 parts of organic pigment, 20-40 parts of water, 1-3 parts of thickener, and 3-6 parts of dispersant; the aqueous resin is an acrylic emulsion. The organic pigment used is zinc titanium red, phthalocyanine blue, or iron oxide yellow. The thickener is a carbamate; The dispersant is sodium lignin xanthate; The leak detection adhesive is prepared using the following method: When 100 parts of water are heated to above 90°C, add 4.5-5.5 parts of polyvinyl alcohol and stir continuously until completely dissolved. Let stand and cool naturally to 70℃-78℃, then slowly add 30-40 parts of ethanol aqueous solution while continuously stirring at a speed of 500-1000r / min; Then add 2-8 parts glycerol, 1-2 parts water-based pigment and 0.1-0.2 parts tributyl phosphate in sequence, and stir to disperse evenly.

2. A method for inspecting leaks in a vacuum forming mold, characterized in that, Includes the following steps: S1. Prepare the leak detection adhesive solution according to claim 1 in advance and perform defoaming treatment; S2. On the surface of the mold, lay a layer of guide net, cover the surface of the guide net with vacuum bag film, seal the vacuum bag film with sealing putty, and install the original feed pipe and the original discharge pipe at both ends of the vacuum bag film respectively. Then install several relay feed pipes between the original feed pipe and the original discharge pipe. S3. Connect the original discharge pipe to the negative pressure device and draw in a negative pressure of -0.1 to -0.08 MPa. Clamp all the relay feed pipes. Draw in the leak detection adhesive at the original feed pipe. The leak detection adhesive enters from the end of the original feed pipe and flows through the first relay feed pipe. Check whether there are any mold leakage points in the area between the original feed pipe and the first relay feed pipe. If there are no leakage points, continue to feed material from the original feed pipe and check the next area. When a clear mold leak is found, mark and record the leak point. Then, change the feed pipe to the next feed pipe after the leak point to introduce the leak detection adhesive. The original feed pipe end is changed to the discharge pipe end. In this way, the leak detection adhesive enters from the first feed pipe and flows towards the original feed pipe end and the original discharge pipe end respectively. On the one hand, the air bubbles formed between the original feed pipe end and the first feed pipe will be drawn to the original feed pipe end, avoiding interference with the leak detection of the next section. On the other hand, the leak detection adhesive continues to soak towards the original discharge pipe end to continue to check the mold sealing of the next section. S4. Continue in this manner until all interval leak detections are completed.

3. The leak detection method for vacuum forming molds according to claim 2, characterized in that, In step S1, the degassing process is as follows: using a vacuum degassing device, the leak detection adhesive is degassed for 3-5 minutes at -0.098~-0.1MPa to eliminate air bubbles before use, so as to avoid small air bubbles in the leak detection adhesive interfering with subsequent testing.

4. The leak detection method for vacuum forming molds according to claim 2, characterized in that, The original feed pipe, the original discharge pipe, and the relay feed pipe are arranged in parallel with a span of 600-1000mm; a tee connector is installed in the middle of each of the original feed pipe, the original discharge pipe, and the relay feed pipe.

5. The leak detection method for vacuum forming molds according to claim 2, characterized in that, In step S3, the criteria for judging the mold leakage point are: when bubbles continuously rise from the bottom, the source of the rising bubbles is the mold leakage point; the method for marking the leakage point is: use a marker to draw a circle on the corresponding position on the surface of the vacuum bag film.

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