CN104198134B - A kind of expansion tank leak-testing apparatus and detection method thereof - Google Patents

Abstract

The invention belongs to detection field of mechanical technique, be specifically related to a kind of expansion tank leak-testing apparatus and detection method thereof.Checkout equipment comprises multiple expansion tank to be detected, frame, grip device and water feed apparatus; Wherein, expansion tank to be detected is made up of glass fiber reinforced plastics composite material, glass fiber reinforced plastics composite material becomes to be grouped into primarily of following parts by weight: novolac resin: 20-40 part, FB resin: 10-20 part, glass fibre: 40-60 part, filler: 5-15 part, hardening agent: 1-3 part, coupling agent: 1-3 part, aging resister: 1-3 part; This expansion tank quality is light, and intensity is high, good corrosion resistance, one-shot forming good integrity, good airproof performance, and cost is low, and the cycle is short, and economic effect is given prominence to.This equipment detection method comprises clamping, water inlet, pressurize and draining, and accuracy and detection efficiency are all higher.

Description

Expansion tank leak detection device and detection method thereof

technical field

The invention belongs to the technical field of detection machinery, and in particular relates to an expansion tank sealing performance detection device and a detection method thereof.

Background technique

Expansion water tank is an important part of hot water heating system and central air-conditioning water system. Its function is to accommodate and compensate the expansion and contraction of water in the system. It is widely used in central air-conditioning, boilers, water heaters, frequency conversion, constant pressure water supply and other equipment. Among them, it can buffer the fluctuation of the system pressure and play the role of stabilizing the pressure and unloading. When the water pressure in the system changes slightly, the automatic expansion and contraction of the airbag of the expansion tank will have a certain buffering effect on the change of the water pressure, which can ensure the stability of the system. The water pressure is stable, and the water pump will not be turned on frequently due to pressure changes.

It can be seen that the sealing performance of the expansion tank is very important. If the air bag of the expansion tank leaks, that is, the sealing performance is not good, and the equipment will be damaged due to excessive pressure or unstable water pressure. performance equipment.

Contents of the invention

The object of the present invention is to provide a detection system and a detection method which can automatically control the detection of whether the sealing performance of the expansion tank is good, and can improve the detection accuracy and detection efficiency.

In order to achieve the above object, one aspect of the present invention provides an expansion tank leak detection device, comprising:

A plurality of expansion water tanks to be detected, the expansion water tanks are made of fiberglass composite material, and the glass fiber reinforced plastic composite material is mainly composed of the following parts by weight: thermoplastic phenolic resin: 20-40 parts, FB resin: 10-20 parts, Glass fiber: 40-60 parts, filler: 5-15 parts, curing agent: 1-3 parts, coupling agent: 1-3 parts, anti-aging agent: 1-3 parts;

Frame, the frame includes an upper panel and a lower panel, the upper panel is provided with a touch screen for running the entire testing equipment, the lower panel includes a console 1 and a console 2, and the console 1 is provided with a fixture device;

A fixture device, which includes a cylinder seat mounted on the frame, a cylinder mounted on the cylinder seat, and a water tank seat arranged above the console one and at the lower end of the cylinder;

Water inlet device, the water inlet device includes a water tank and a water pump arranged inside the lower panel, and a water storage tank for filling water into the expansion tank, between the water tank and the water pump, between the water pump and the water storage tank, and between the water tank and the water tank It is connected with the expansion tank through water pipes, and a manual ball valve and sealing valve are installed between the water storage tank and the expansion tank; an electrically controlled overflow valve is installed between the water tank and the expansion tank; the detected expansion tank is placed near the water tank. On the seat, when testing, the cylinder presses down on the expansion tank, connects the water pipe to the expansion tank, and the water pump starts to feed water into the expansion tank;

Wherein, the expansion water tank to be tested is placed on the water tank seat, and during detection, the cylinder presses the expansion water tank downward, the water pipe is connected with the expansion water tank, and the water pump starts to feed water into the expansion water tank. However, the tested expansion tank of the present invention is made of the above-mentioned glass fiber reinforced plastic composite material. Compared with the expansion tank made of alloy materials such as stainless steel in the prior art, the tested expansion tank of the present invention is light in weight, and only approximately made of steel 20-25% of the expansion tank, but the strength is close to that of the expansion tank made of steel, or even higher, and can completely replace the steel expansion tank. Moreover, the process of preparing the expansion water tank with the FRP composite material in the present invention is simple, can be formed at one time, and has good integrity. Compared with the preparation of the expansion water tank with alloy materials such as steel, it does not need to carry out gold processing technology, which greatly saves the processing steps and processing tools. And other equipment costs, low cost, short cycle, outstanding economic effect. In addition, the expansion water tank made by the present invention has very good corrosion resistance, and has good resistance to the atmosphere, water, and general concentrations of acids, alkalis, salts, and various oils and solvents, which expands the expansion tank of the present invention. application range.

Moreover, the FB composite material for the expansion tank prepared by the present invention has reasonable compatibility, the decomposition temperature of the FB resin in the raw material is >500°C, the oxygen index is 48.5, and it has excellent bonding properties to glass fibers and fillers. Mixed use, glass fiber, filler and other raw materials are bonded together to make a hard expansion tank product that can withstand tensile stress, bending, compression and shear stress, and can greatly increase the working temperature of the product expansion tank. There is a problem that the strength and other properties are obviously reduced when the temperature rises under high temperature or after long-term work. In addition, aging phenomenon is a common defect of products such as plastics and glass fiber reinforced plastics, and aging will easily lead to a decline in the performance of the product, so the present invention adds an anti-aging agent to the formula of the fiberglass reinforced plastic composite material to delay the aging of the expansion tank of the product and make its service life longer, and the anti-aging agent can choose any commercially available anti-aging agent that meets the requirements of the present invention.

In the above-mentioned a kind of expansion tank tightness detection equipment, described glass fiber is one or more in S-1 glass fiber, S-2 glass fiber, S-3 glass fiber; The diameter of described glass fiber is 3 -8μm, length 5-10mm. The S series glass fibers selected by the present invention are high-strength glass fibers, which have obvious performance advantages compared with ordinary glass fibers (such as E glass fibers). As the main raw material of the glass fiber reinforced plastic composite material, the present invention selects the S series glass fiber with more obvious performance advantages, so that the performance of the product expansion tank is more superior.

In the above-mentioned leak detection device for an expansion tank, the filler is one or more of kaolin, talcum powder, and calcium carbonate; the particle size of the filler is 1-3 μm. The filler mainly plays the role of filling, enhancing strength and other performances, and reducing costs. Fillers with a smaller particle size range are selected to avoid defects such as voids and loose bonding in the expansion tank of the product due to excessive particle size, and to prevent surface irregularities. Smooth question.

In the above-mentioned expansion tank leak detection device, the curing agent is one or both of hexamethylenetetramine and hexamethylenetetramine. Since thermoplastic phenolic resin itself does not have the ability to cure, it is necessary to add curing agents urotropine and hexamethylenetetramine, which can decompose methylene during the process of melting with phenolic resin, and play a role in crosslinking. Accelerates the curing of thermoplastic phenolic resins. Of course, its dosage should neither be too little nor too much. If it is too little, the degree of curing and crosslinking of the resin will be insufficient, and the strength and other properties of the product expansion tank will be low; if it is too much, the crosslinking reaction of the resin will be excessive, and there will be many defects. The obvious brittleness will also cause the strength, toughness and other properties of the expansion tank of the product to decline. Therefore, the amount of the curing agent added is controlled within the above range according to the amount of the thermoplastic phenolic resin of the present invention.

In addition, 0.5-1.5 parts of accelerator can be added together with the curing agent to accelerate the cross-linking reaction between the thermoplastic phenolic resin and the curing agent, lower the curing temperature and shorten the curing time. The accelerator is preferably magnesium oxide, with a particle size of 1-3 μm.

In the above-mentioned expansion tank leak detection device, the coupling agent is one or more of a silane coupling agent and a titanate coupling agent. The coupling agent can undergo exchange reaction on the surface of the fiber, or react with the resin, and dissolve well on the surface of the resin, thereby improving the bonding force between layers and increasing the shear strength of the product.

In addition, the present invention can also add 10-20 parts of reinforcing fibers to the glass fiber reinforced plastic composite material used for the preparation of the expansion tank. The diameter of the reinforcing fibers is also 3-8 μm and the length is also 5-10 mm. The reinforcing fiber can be one or more of carbon fiber, boron fiber, aramid fiber, alumina fiber, silicon carbide fiber, and these high-performance reinforcing fibers can further enhance the strength of the expansion tank of the FRP composite product of the present invention, etc. performance.

In the above-mentioned expansion tank leak detection device, the preparation method of the expansion tank includes the following steps:

Mixing ingredients: Weigh the raw materials according to the composition and parts by weight of the above-mentioned expansion tank, put them into a high-speed mixer and mix them evenly;

Granulation: Put the above-mentioned uniformly mixed materials into the feeding hopper of the twin-screw extruder, feed them into the twin-screw extruder from the feeding hopper, extrude from the head of the twin-screw extruder, and pass through the granulator to produce pellets to obtain pellets;

Injection molding: Add the pellets obtained above into the barrel of the injection molding machine, heat it to a molten state, and then inject the molten raw material into the mold of the expansion water tank through the nozzle, pressurize, cool and form, and open the mold to make the expansion water tank .

In the above-mentioned expansion tank leak detection equipment, during the granulation process, the temperature of the twin-screw extruder is set at 230-290° C., and the rotation speed is 20-60 r/min.

In the above-mentioned expansion tank leak detection equipment, during the injection molding process, the nozzle temperature is 250-300°C, the mold temperature is 120-160°C, the injection pressure is 80-100MPa, the injection time is 3-8s, and the pressure holding time is 3-8s. The pressure is 50-70MPa, the holding time is 30-80s, and the cooling time is 1-3min.

In the above-mentioned expansion water tank sealing test equipment, the second operating platform is provided with a drying device, and the drying device includes an expansion tank fixing seat frame, and a fixing seat for fixing the expansion water tank placed on the expansion water tank fixing seat frame And the detected expansion water tank placed on the fixed seat and waiting to be dried.

Another object of the present invention is to provide a detection method using the above-mentioned detection equipment, comprising the following steps:

Clamping: Place the detected expansion tank on the water tank seat, connect the water pipe to the detected expansion tank, press the start button on the touch screen, the cylinder presses down and compresses the detected expansion tank;

Water intake: Open the manual ball valve and sealing valve, and the water storage tank will fill the detected expansion tank with water until the water intake time preset by the device is reached. At this time, the device will judge the pressure value in the detected expansion tank. If the pressure value is lower than the detection requirement If the pressure is higher than the maximum set value, the overflow valve will be controlled to open and the excess water will be drained back to the sink;

Pressure holding: close the sealing valve, and monitor the pressure value in the expansion tank to be detected during the preset pressure holding time period. If the pressure value after the pressure holding is lower than the pressure value of 5KPa during the pressure holding time period, the touch screen will alarm information;

Drainage: After the test, close the sealing valve, close the overflow valve, disconnect the water pipe connected to the expansion tank, restore the cylinder to its original position, and place the tested expansion tank on the drying device to drain to the sink.

Compared with the prior art, the present invention has the following advantages:

1. The present invention utilizes the process of program control testing equipment to test the tightness of the expansion tank, which improves the detection accuracy. By injecting water into the detected expansion tank, detecting and monitoring the real-time pressure in the expansion tank to determine whether there is leakage in the expansion tank, and The detection results are displayed on the touch screen, which is used to facilitate human-computer interaction, which greatly reduces the detection time and improves the detection efficiency.

2. The expansion water tank to be tested in the present invention is made of fiberglass composite material, which is light in weight, high in strength, and very good in corrosion resistance. It has better resistance, can completely replace steel to prepare expansion water tanks, and expands the application range of the expansion water tanks of the present invention.

3. The FRP composite materials used in the preparation of expansion tanks in the present invention have reasonable compatibility, and can be made into hard expansion tank products that can withstand tensile stress, bending, compression and shear stress, and can greatly increase the working temperature of the product expansion tank without occurrence of At high temperature or after long-term work, the temperature rises and the strength and other properties are obviously reduced.

4. In the present invention, the process of preparing the expansion water tank with the FRP composite material is simple, one-time forming, and the integrity is good. Compared with the preparation of the expansion water tank with alloy materials such as steel, no gold processing technology is required, which greatly saves the processing steps and processing tools And other equipment costs, low cost, short cycle, outstanding economic effect.

5. The expansion water tank of the present invention is made of fiberglass composite material at one time, and has very good sealing performance.

Description of drawings

Fig. 1 is the explosion diagram of equipment of the present invention;

Fig. 2 is a principle diagram of the detection of the present invention.

In the figure: water tank 100; frame 200; fixture device 300; water inlet device 400; upper panel 210; lower panel 220; touch screen 211; console one 221; console two 222; cylinder seat 310; cylinder 320; 330; water tank 410; water pump 420; water storage tank 430; water pipe 440; manual ball valve 450; sealing valve 460; overflow valve 470;

Detailed ways

The present invention will be further described below in conjunction with accompanying drawing.

As shown in FIG. 1 , an expansion tank leak detection device includes: a plurality of expansion tanks 100 to be tested, a frame 200 , a fixture device 300 , a water inlet assembly 400 and a drying device 500 .

The frame 200 includes an upper panel 210 and a lower panel 220 , the upper panel 210 is provided with a touch screen 211 , the lower panel 220 includes a console 1 221 and a console 2 222 , and the console 1 221 is provided with a fixture device 300 .

The fixture device 300 includes a cylinder base 310 mounted on the frame 100 , a cylinder 320 mounted on the cylinder base 310 , and a water tank seat 330 located above the console 1 221 and at the lower end of the cylinder 320 .

The water inlet device 400 includes a water tank 410 and a water pump 420 arranged inside the lower panel 220, and a water storage tank 430 for filling water into the expansion tank 100, between the water tank 410 and the water pump 420, the water pump 420 and the water storage tank 430 Between the water tank 410 and the expansion tank 100 are connected by a water pipe 440, and a manual ball valve 450 and a sealing valve 460 are installed between the water storage tank 430 and the expansion tank 100; The overflow valve 470, wherein the tested expansion water tank 100 is placed on the water tank seat 330. During the detection, the cylinder 320 presses the expansion water tank 100 downward, connects the water pipe 440 with the expansion water tank 100, and the water pump 420 starts to flow into the expansion water tank 100. Ingress of water.

The operating platform 2 is provided with a drying device 500, and the drying device 500 includes a fixed seat frame 510 of the expansion tank 100, a fixed seat 520 for fixing the expansion water tank 100 placed on the fixed seat frame 510 of the expansion tank, and a fixed seat 520 placed on the fixed seat 520, and The detected expansion water tank 100 waiting to be dried.

As shown in Figure 2, the present invention also provides a detection method using the above-mentioned detection equipment:

Clamping: place the detected expansion tank 100 on the water tank seat 330, connect the water pipe 440 with the detected expansion tank 100, press the start button on the touch screen 211, the cylinder 320 presses down and compresses the detected expansion water tank 100;

Water intake: Open the manual ball valve 450 and the sealing valve 460, and the water storage tank 430 will fill the detected expansion tank 100 with water until the water intake time preset by the device is reached. At this time, the device will judge the pressure value in the detected expansion tank 100. If the pressure If the pressure value is lower than the minimum pressure required by the detection, an alarm message will be displayed on the touch screen 211;

Pressure holding: close the sealing valve 460, and monitor the pressure value in the expansion tank 100 within the preset pressure holding time period. If the pressure value after the pressure holding is lower than 5KPa during the pressure holding time period, then The system alarms and shuts down, and now the touch screen 211 displays alarm information.

Drainage: After the test is completed, close the sealing valve 460, close the overflow valve 470, disconnect the water pipe 440 connected to the expansion tank 100, restore the cylinder 320 to its original position, and place the detected expansion tank 100 on the drying device 500 to drain to the water tank 410 .

The realization of the present invention is to use the program to control the detection equipment to test the sealing of the expansion tank, which improves the detection accuracy. By injecting water into the detected expansion tank, detecting and monitoring the real-time pressure in the expansion tank to determine whether there is leakage in the expansion tank, and The detection results are displayed on the touch screen, which is used to facilitate human-computer interaction, which greatly reduces the detection time and improves the detection efficiency.

The above-mentioned expansion tank to be tested is made of fiberglass composite material, and the fiberglass composite material is mainly composed of the following parts by weight: thermoplastic phenolic resin: 20-40 parts, FB resin: 10-20 parts, glass fiber: 40-60 parts, Filler: 5-15 parts, curing agent: 1-3 parts, coupling agent: 1-3 parts, anti-aging agent: 1-3 parts. Among them, the glass fiber, filler, accelerator and reinforcing fiber can be mixed with other components at high speed after soaking in the liquid oligomeric phenolic resin added with surfactant for 24-48 hours.

Table 1: Components and parts by weight of expansion tanks of Examples 1-5 of the present invention

Example 1:

Take the raw material by the composition and parts by weight of the expansion tank of Example 1 in Table 1, the particle diameter of the powder in the raw material is 1-2 micron, the diameter of the fiber is 3-5 μm, and the length is 5-8mm, drop into Mix well in a high-speed mixer. Then put the uniformly mixed material into the feeding hopper of the twin-screw extruder, and feed it into the twin-screw extruder from the feeding hopper. Extrude from the head of a twin-screw extruder, and granulate through a granulator to obtain pellets.

Then put the obtained pellets into the barrel of the injection molding machine, heat to the molten state, and spray the molten raw material into the mold of the expansion tank through a nozzle with a temperature of 250°C and a pressure of 80MPa, and the injection time is 8s , the mold is preheated to 120°C. Finally, keep the pressure for 80s under the condition of 50MPa, cool for 1min, form and open the mold to obtain the expansion tank.

Example 2:

Take by weighing raw material by the composition of embodiment 2 expansion tank in table 1 and parts by weight thereof, the particle diameter of powder in the raw material is 1-2 micron, and the diameter of fiber is 4-6 μ m, and length is 6-8mm, drops into Mix well in a high-speed mixer. Then put the uniformly mixed material into the feeding hopper of the twin-screw extruder, and feed it into the twin-screw extruder from the feeding hopper. Extrude from the head of a twin-screw extruder, and granulate through a granulator to obtain pellets.

Then put the obtained pellets into the barrel of the injection molding machine, heat to the molten state, and spray the molten raw material into the mold of the expansion tank through a nozzle with a temperature of 280°C and a pressure of 90 MPa, and the injection time is 6s. , the mold is preheated to 140°C. Finally, keep the pressure at 65MPa for 50s, cool for 2min, form and open the mold to obtain the expansion tank.

Example 3:

Take the raw material by the composition and parts by weight of the expansion tank of Example 3 in Table 1, and take by weighing 0.5 parts of accelerator magnesium oxide and 10 parts of reinforcing carbon fiber. The particle diameter of the powder in the raw material is 1-2 microns, The diameter of the fiber is 4-6μm, the length is 6-8mm, put into the high-speed mixer and mix evenly. Then put the uniformly mixed material into the feeding hopper of the twin-screw extruder, and feed it into the twin-screw extruder from the feeding hopper. Extrude from the head of a twin-screw extruder, and granulate through a granulator to obtain pellets.

Then put the obtained pellets into the barrel of the injection molding machine, heat to the molten state, and spray the molten raw material into the mold of the expansion tank through a nozzle with a temperature of 280°C and a pressure of 90 MPa, and the injection time is 6s. , the mold is preheated to 140°C. Finally, keep the pressure at 65MPa for 50s, cool for 2min, form and open the mold to obtain the expansion tank.

Example 4:

Weigh the raw materials according to the composition and parts by weight of the expansion tank of Example 4 in Table 1, and take by weighing 1 part of accelerator magnesium oxide and 15 parts of reinforcing aramid fiber. The particle size of the powder in the raw material is 2-3 Micron, the diameter of the fiber is 5-8 μm, and the length is 7-9mm, put it into a high-speed mixer and mix evenly. Then put the uniformly mixed material into the feeding hopper of the twin-screw extruder, and feed it into the twin-screw extruder from the feeding hopper. Extrude from the head of a twin-screw extruder, and granulate through a granulator to obtain pellets.

Then put the obtained pellets into the barrel of the injection molding machine, heat it to a molten state, and spray the molten raw material into the mold of the expansion tank through a nozzle with a temperature of 280°C and a pressure of 95MPa, and the injection time is 5s. , the mold is preheated to 150°C. Finally, keep the pressure for 45 seconds under the condition of 68 MPa, cool for 2 minutes, form and open the mold to obtain the expansion tank.

Example 5:

Weigh the raw materials according to the composition and parts by weight of the expansion tank of Example 5 in Table 1, and take by weighing 1.5 parts of accelerator magnesium oxide and 20 parts of reinforcing silicon carbide fibers. The particle diameter of the powder in the raw materials is 2-3 Micron, the diameter of the fiber is 6-8μm, and the length is 8-10mm, put it into a high-speed mixer and mix evenly. Then put the uniformly mixed material into the feeding hopper of the twin-screw extruder, and feed it into the twin-screw extruder from the feeding hopper. Extrude from the head of a twin-screw extruder, and granulate through a granulator to obtain pellets.

Then put the obtained pellets into the barrel of the injection molding machine, heat it to a molten state, and spray the molten raw material into the mold of the expansion tank through a nozzle with a temperature of 300°C and a pressure of 100 MPa, and the injection time is 3s. , the mold is preheated to 160°C. Finally, keep the pressure for 30s under the condition of 70MPa, cool for 3min, form and open the mold to obtain the expansion tank.

The expansion tanks prepared in Examples 1-5 of the present invention were tested for mechanical properties, and the test results are shown in Table 2.

Table 2: Mechanical performance test results of the expansion tank made in Examples 1-5 of the present invention

As can be seen from Table 2, the expansion tank made of reasonable FRP composite material in the present invention has excellent mechanical properties, can completely replace the expansion tank made of alloy materials such as stainless steel, and is light in weight, good in corrosion resistance, simple in preparation process and cycle time Short, low cost, through one-time molding, good integrity, excellent sealing, and outstanding economic effect.

The expansion water tanks prepared in Examples 1-5 of the present invention were tested for their sealing performance by using the expansion tank sealing performance testing equipment and testing method of the present invention, all of which met the test requirements and had outstanding sealing effects.

The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which the present invention belongs can make various modifications or supplements to the described specific embodiments or adopt similar methods to replace them, but they will not deviate from the spirit of the present invention or go beyond the definition of the appended claims range.

Claims (6)

1. An expansion tank leak detection device, characterized in that, comprising: A plurality of expansion water tanks to be detected, the expansion water tanks are made of fiberglass composite material, and the glass fiber reinforced plastic composite material is mainly composed of the following parts by weight: thermoplastic phenolic resin: 20-40 parts, FB resin: 10-20 parts, Glass fiber: 40-60 parts, filler: 5-15 parts, curing agent: 1-3 parts, coupling agent: 1-3 parts, anti-aging agent: 1-3 parts; the glass fiber is S-1 glass fiber 1. One or more of S-2 glass fibers and S-3 glass fibers; the glass fibers have a diameter of 3-8 μm and a length of 5-10 mm; Frame, the frame includes an upper panel and a lower panel, the upper panel is provided with a touch screen for running the entire detection equipment, the lower panel includes a console 1 and a console 2, the console 1 is provided with a fixture device, A drying device is provided on the second operating platform; A fixture device, which includes a cylinder seat mounted on the frame, a cylinder mounted on the cylinder seat, and a water tank seat arranged above the console one and at the lower end of the cylinder; A drying device, the drying device includes a fixed seat for the expansion tank, a fixed seat for fixing the expansion tank placed on the fixed seat for the expansion tank, and a detected expansion tank placed on the fixed seat and waiting to be aired; Water inlet device, the water inlet device includes a water tank and a water pump arranged inside the lower panel, and a water storage tank for filling water into the expansion tank, between the water tank and the water pump, between the water pump and the water storage tank, and between the water tank and the water tank It is connected with the expansion tank through water pipes, and a manual ball valve and sealing valve are installed between the water storage tank and the expansion tank; an electrically controlled overflow valve is installed between the water tank and the expansion tank; the detected expansion tank is placed near the water tank. On the seat, during detection, the cylinder presses down on the expansion tank, connects the water pipe to the expansion tank, and the water pump starts to feed water into the expansion tank; the method for testing the tightness of the expansion tank includes the following steps: Clamping: Place the detected expansion tank on the water tank seat, connect the water pipe to the detected expansion tank, press the start button on the touch screen, the cylinder presses down and compresses the detected expansion tank; Water intake: Open the manual ball valve and sealing valve, and the water storage tank will fill the detected expansion tank with water until the water intake time preset by the device is reached. At this time, the device will judge the pressure value in the detected expansion tank. If the pressure value is lower than the detection requirement If the pressure is higher than the maximum set value, the overflow valve will be controlled to open and the excess water will be drained back to the sink; Pressure holding: close the sealing valve, and monitor the pressure value in the expansion tank to be detected during the preset pressure holding time period. If the pressure value after the pressure holding is lower than the pressure value of 5KPa during the pressure holding time period, the touch screen will alarm information; Drainage: After the test, close the sealing valve, close the overflow valve, disconnect the water pipe connected to the expansion tank, restore the cylinder to its original position, and place the tested expansion tank on the drying device to drain to the sink. 2. A kind of expansion tank sealing test equipment according to claim 1, is characterized in that, described filler is one or more in kaolin, talcum powder, calcium carbonate; The particle diameter of described filler is 1-3 μ m . 3. An expansion tank leak test device according to claim 1, wherein the coupling agent is one or more of a silane coupling agent and a titanate coupling agent. 4. A kind of expansion tank leak test equipment according to claim 1, is characterized in that, the preparation method of described expansion tank comprises the following steps: Mixed ingredients: take the raw materials according to the composition and parts by weight of the expansion tank described in claim 1, put them into a high-speed mixer and mix evenly; Granulation: Put the above-mentioned uniformly mixed materials into the feeding hopper of the twin-screw extruder, feed them into the twin-screw extruder from the feeding hopper, extrude from the head of the twin-screw extruder, and pass through the granulator to produce pellets to obtain pellets; Injection molding: Add the pellets obtained above into the barrel of the injection molding machine, heat it to a molten state, and then inject the molten raw material into the mold of the expansion water tank through the nozzle, pressurize, cool and form, and open the mold to make the expansion water tank . 5 . The device for testing the tightness of an expansion tank according to claim 4 , wherein, during the granulation process, the temperature of the twin-screw extruder is set at 230-290° C., and the rotation speed is 20-60 r/min. 6. An expansion tank leak test device according to claim 4, characterized in that, during the injection molding process, the nozzle temperature is 250-300°C, the mold temperature is 120-160°C, and the injection pressure is 80-100MPa, The injection time is 3-8s, the holding pressure is 50-70MPa, the holding time is 30-80s, and the cooling time is 1-3min.