Preparation process for plasma high-temperature spraying of enamel in inner cavity of valve

Abstract

The invention discloses a preparation process for plasma high-temperature spraying of enamel in an inner cavity of a valve, which is characterized by comprising the following steps of: (1) diluting enamel glaze into a mixed solution by using water, putting the mixed solution into a storage tank, and inputting the mixed solution into the valve by using an input pipeline to be butted with a water inlet end of the valve, so that the inner cavity of the valve is filled with the mixed solution; (2) a storage tank is communicated with a plasma spray gun through a pipeline, the plasma spray gun extends into the valve from a middle through hole of the valve, the plasma spray gun is aligned to the center of the liquid level, and the plasma spray gun is started to enable part of the mixed solution to be sucked into the plasma spray gun to form jet flow; and (3) opening the water outlet end of the valve, lowering the liquid level of the mixed solution, increasing the depth of the plasma spray gun entering the valve, and stopping spraying by the plasma spray gun until the mixed solution in the valve is completely discharged. The device has the beneficial effects that jet flow of plasma injection is utilized to stimulate liquid surface vibration and cavitation of a mixed solution, and the inner cavity of the valve is promoted to be fully combined with enamel glaze.

Description

Technical Field

[0001] The invention relates to a valve inner surface treatment process, in particular to a preparation process for valve inner cavity enamel by plasma high temperature spraying. Background Art

[0002] Cast iron valves are often used in water supply and drainage systems. The inner surface of the valve needs to be protected by a protective layer, usually sprayed with paint or epoxy resin. This valve surface treatment process is not environmentally friendly and is prone to secondary pollution. It is not ideal for acid resistance, alkali resistance and salt resistance, and is easily corroded in acid, alkali and salt environments. At the same time, it is powerless to deal with tiny pores, cracks and other defects generated in the casting process of the valve casting, which affects the flatness of the inner surface of the valve. The above technical difficulties make cast iron valves generally only used in ordinary civil and industrial drainage pipes.

[0003] For example, the Chinese invention patent authorization announcement number CN105060714B discloses a composite enamel for cast iron valves and its preparation and coating method. First, a mixed rubber material is prepared. The mixed rubber material uses epoxy resin and polyvinyl chloride as important auxiliary materials to enhance the adhesion and toughness of the enamel, so that the formed enamel protective layer has hardness and smoothness while also having a certain elasticity. The multiple coating method ensures that the mixed solution is in full and uniform contact with the inner wall of the valve, and the thickness of the composite enamel can be controlled as needed. However, this coating method requires multiple coatings on the inside of the valve, which is cumbersome to operate.

[0004] Another example is China's invention patent publication number CN113699528A, which discloses a process for preparing plasma thermal spray powder for enamel production. By powderizing and wrapping the enamel glaze particles, the requirements of the plasma thermal spray process can be met, and the plasma thermal spray process can be used in the production of enamel products. However, this process requires a uniform mobile spray gun to ensure the thickness and uniformity of the coating. For the internal structure of the valve, it is necessary to select a suitable spray gun angle and spraying method according to the specific situation. If it is manually operated, the quality requirements of the operator are high and the labor intensity is high. If it is automatically operated by a robot, the investment cost is high.

[0005] Another example is the Chinese invention patent authorization announcement number CN106521398B, which discloses a method for plasma spraying enamel coating on titanium alloy surface and hot rolling treatment. Through the preparation of plasma sprayed enamel coating and hot rolling treatment, a corrosion-resistant coating with few holes and cracks and a dense structure is prepared. If this patent is used for spraying enamel for the inner cavity of the invention, highly automated plasma spraying equipment is also required. Summary of the invention

[0006] The present invention aims to solve the many drawbacks of the existing valve inner cavity enamel preparation process, and to provide a valve inner cavity enamel preparation process by plasma high temperature spraying without rotating the plasma spray gun.

[0007] The technical scheme of the present invention is: a preparation process for high-temperature plasma spraying of valve inner cavity enamel, comprising the following steps: (1) diluting enamel glaze with water to form a mixed solution, placing the mixed solution in a storage tank, opening the water inlet end of the valve, and connecting the mixed solution with the water inlet end of the valve by using an input pipe to input the mixed solution into the valve, so that the valve inner cavity is filled with the mixed solution; (2) connecting the storage tank with a plasma spray gun through a pipe, extending the plasma spray gun into the valve from the middle through hole of the valve, aiming the plasma spray gun at the center of the liquid surface, turning on the plasma spray gun so that part of the mixed solution is sucked into the plasma spray gun to form a jet, and the jet is sprayed into the valve to cause the liquid surface vibration and cavitation of the mixed solution in the valve, so as to promote the enamel glaze in the liquid surface area to fully combine with the valve inner cavity; (3) opening the water outlet end of the valve, the liquid surface of the mixed solution drops, and the depth of the plasma spray gun entering the valve is also increased, until the mixed solution in the valve is completely discharged and the plasma spray gun stops spraying.

[0008] The preparation of the enamel material in the above scheme includes the following steps: Preparation of the glue material: 12-16 parts of epoxy resin, 6-10 parts of active calcium carbonate and 4-8 parts of zinc oxide are mixed and ground into a powder mixture, and the mixture is put into an internal mixer for mixing for 20-30 minutes. During the mixing process, 20-30 parts of borax are added twice, 30% borax is added for the first time, and 70% borax is added for the second time. When the temperature reaches 530-550°C, the material is discharged, and the discharged material is naturally cooled to room temperature to obtain glue material A; 3-7 parts of polyvinyl chloride, 30-40 parts of silicon dioxide, 10-20 parts of The talcum powder and 5-10 parts of silicon carbide are mixed and ground evenly into a powder mixture, and then put into an internal mixer for mixing for 20-30 minutes. During the mixing process, 8-12 parts of titanium dioxide are added twice, 70% of titanium dioxide is added for the first time, and 30% of titanium dioxide is added for the second time. When the temperature reaches 560-570°C, the material is discharged, and the discharged material is naturally cooled to room temperature to obtain rubber material B; the rubber materials A and rubber material B are mixed and put into a centrifuge for centrifugation for 10-20 minutes to form an enamel glaze material. The centrifugal speed is 200-300r / min, and the temperature is maintained at 600-620°C during centrifugation.

[0009] The mixed solution in the above scheme is discharged from the water outlet of the valve and then returns to the storage tank through the circulation pipeline.

[0010] The beneficial effect of the present invention is that the coating process and the plasma spraying process are combined, and the plasma jet is used to stimulate the liquid surface vibration and cavitation of the mixed solution, so that the valve cavity area near the liquid surface is fully combined with the enamel glaze. It is only necessary to adjust the depth of the plasma spray gun in the valve cavity by synchronizing the drop of the liquid level to complete the uniform attachment of the enamel to the valve cavity at one time, without the need for manual or automatic control of the plasma spray gun to perform complex operations in the valve cavity. DETAILED DESCRIPTION

[0011] The present invention will be further described below in conjunction with the embodiments.

[0012] The preparation process of the enamel of the inner cavity of the valve by plasma high temperature spraying comprises the following steps: (1) diluting the enamel glaze with water to form a mixed solution, placing the mixed solution in a storage tank, opening the water inlet end of the valve, closing the water outlet end of the valve, and connecting the input pipe with the water inlet end of the valve to input the mixed solution into the valve. Specifically, the mixed solution in the storage tank can be introduced into the valve by using the communicating vessel principle, or the mixed solution in the storage tank can be introduced into the valve by using a power device, so that the inner cavity of the valve is filled with the mixed solution; (2) connecting the storage tank with the plasma spray gun through a pipe, and the pipe can be provided with The solenoid valve is used to control the opening and closing. The plasma spray gun extends into the valve from the middle hole of the valve. The plasma spray gun is aimed at the center of the liquid surface. The plasma spray gun and the solenoid valve are turned on so that part of the mixed solution is sucked into the plasma spray gun to form a jet. The jet is sprayed into the valve to cause the liquid surface vibration and cavitation of the mixed solution inside the valve, which promotes the enamel glaze in the liquid surface area to fully combine with the inner cavity of the valve; (3) The water outlet of the valve is opened, the liquid level of the mixed solution drops, and the depth of the plasma spray gun entering the valve is also increased until the mixed solution in the valve is drained and the plasma spray gun stops spraying. The valve referred to here refers to a hollow valve cavity without valve stem, valve disc and other parts installed. After the mixed solution is discharged from the water outlet of the valve, it returns to the storage tank through the circulation pipeline. The mixed solution can be recovered for the next use.

[0013] The bonding force between the enamel glaze and the inner surface of the valve, the uniformity of the enamel glaze, and the thickness of the enamel glaze of the present invention are equivalent to the method of filling the valve and then stirring provided by China Invention Patent Authorization Announcement No. CN105060714B, and at the same time, the method is easy to operate, can be formed in one step, and shortens the processing time.

[0014] The production process of the present invention does not generate any pollutants, the utilization rate of all raw materials is 100%, and there is no secondary pollution; because borax and activated calcium carbonate are added, the mixed solution has excellent lubricity, fluidity, dispersibility and organicity, and has strong affinity with rubber and plastic molecules; the acid resistance, alkali resistance and salt resistance are all better than ordinary enamel and spraying processes, and the mixed solution uses water as a carrier to evenly coat the mixed rubber on the inner surface of the valve, which can repair defects such as tiny pores and cracks on the valve surface caused by defects in the manufacturing process, so that the protective layer of the valve inner cavity is uniform.

Claims

1. The preparation process of the enamel of the inner cavity of the valve by plasma high temperature spraying is characterized by: The following steps are involved: (1) Dilute the enamel glaze with water to form a mixed solution, place it in a storage tank, open the water inlet end of the valve, and use the input pipe to connect the water inlet end of the valve to input the mixed solution into the valve, so that the valve cavity is filled with the mixed solution; (2) Connect the storage tank and the plasma spray gun through a pipe, extend the plasma spray gun into the valve through the middle hole of the valve, aim the plasma spray gun at the center of the liquid surface, turn on the plasma spray gun so that part of the mixed solution is sucked into the plasma spray gun to form a jet, and the jet is sprayed into the valve to cause the liquid surface vibration and cavitation of the mixed solution inside the valve, so as to promote the enamel glaze in the liquid surface area to fully combine with the valve cavity; (3) Open the water outlet end of the valve, the liquid level of the mixed solution drops, and the depth of the plasma spray gun entering the valve also increases, until the mixed solution in the valve is completely discharged and the plasma spray gun stops spraying.

2. The process for preparing valve inner cavity enamel by plasma high temperature spraying as claimed in claim 1 is characterized by: The preparation of the enamel glaze comprises the following steps: preparation of the glue: 12-16 parts of epoxy resin, 6-10 parts of active calcium carbonate and 4-8 parts of zinc oxide are mixed and ground into a powder mixture, and the mixture is put into an internal mixer for mixing for 20-30 minutes. During the mixing process, 20-30 parts of borax are added twice, 30% borax is added for the first time, and 70% borax is added for the second time. When the temperature reaches 530-550°C, the material is discharged, and the discharged material is naturally cooled to room temperature to obtain the glue A; 3-7 parts of polyvinyl chloride, 30-40 parts of silicon dioxide, 10-20 parts of slip are added. The stone powder and 5-10 parts of silicon carbide are evenly mixed and ground into a powder mixture, and then put into an internal mixer for mixing for 20-30 minutes. During the mixing process, 8-12 parts of titanium dioxide are added twice, 70% of titanium dioxide is added for the first time, and 30% of titanium dioxide is added for the second time. When the temperature reaches 560-570°C, the material is discharged, and the discharged material is naturally cooled to room temperature to obtain rubber material B; the rubber materials A and rubber materials B are mixed and put into a centrifuge for centrifugation for 10-20 minutes to form enamel glaze. The centrifugal speed is 200-300r / min, and the temperature is maintained at 600-620°C during centrifugation.

3. The process for preparing valve inner cavity enamel by plasma high temperature spraying as claimed in claim 1 is characterized by: The mixed solution is discharged from the water outlet of the valve and then returns to the storage tank through the circulation pipeline.