CN101660618A - Hard sealing ball valve and production process thereof - Google Patents

Abstract

The invention discloses a hard sealing ball valve that is applicable to high wear and strong corrosion conditions and solves the problem of easy embrittlement of ceramic ball valves and a production process thereof. The ball valve is characterized in that a ceramic layer is respectively plasma sprayed on fitting surfaces of a ball body and a valve seat. Due to the characteristics of wear resistance and corrosion protection of ceramic materials, the ball valve has good inner sealing performance and service life under such extreme conditions as high wear, strong corrosion, high temperature, highpressure and the like. Moreover, the valve seat, the ball body and the valve body are still made of metals, which prevents embrittlement of the valve seat and the valve body. When the ball body and the valve seat are machined, a ceramic material with certain thickness is respectively coated on the fitting surfaces of the ball body and the valve seat to form the ceramic layer; then the fitting surfaces of the ball body and the valve seat are ground respectively, and finally the ball body and the valve seat are assembled and mutually ground to cause hard seal fit of the ball body and the valveseat, reach fit accuracy of the valve body and the valve seat required by hard seal and improve sealing performance of the high hard sealing ball valve.

Description

Hard seal ball valve and its production process

technical field

The invention relates to a hard-sealed ball valve and a production process thereof.

Background technique

The existing metal hard-sealed ball valve includes a valve body provided with at least one inlet and outlet, a valve seat installed in the inner cavity of the valve body, and a ball that is hard-sealed with the valve seat. The flow passage for selectively connecting or disconnecting the inlet and outlet of the valve body when rotating, the valve body, valve seat and ball are all made of metal materials. Due to the steel-to-steel hard seal between the ball and the valve seat, the inner seal of the ball valve has certain temperature resistance and wear resistance. However, limited by the properties of metal materials, the above-mentioned metal hard-sealed ball valves are increasingly unable to meet the needs of high-temperature, high-wear, and strong-corrosion harsh working conditions containing solid particles, dust, pulp, and chemical slurries. The main reason is that the service life is short. , poor sealing effect, serious leakage, etc., greatly affect the stability of the system operation.

In order to improve the performance of ball valves, ceramic ball valves have appeared. The characteristic of the ceramic ball valve is that the ball and the valve seat are all made of ceramic materials. Due to the high tensile strength, compressive strength, elastic modulus, and hardness of ceramic materials, they have excellent wear-resistant and anti-corrosion properties, which can improve the service life and scope of application of ball valves. However, since the ball and the valve seat are made of ceramic material as a whole, it is not only easy to be brittle, but also has a high cost.

Contents of the invention

The invention aims to provide a hard-sealed ball valve and its production process which are suitable for high wear and strong corrosion working conditions and solve the problem that the ceramic ball valve is easy to be brittle.

In order to solve the above-mentioned technical problems, the hard-sealed ball valve provided by the present invention includes a valve body provided with at least one inlet and outlet, a valve seat installed in the inner cavity of the valve body, and a ball hard-sealed with the valve seat. The ball is processed with a flow channel that can selectively connect or disconnect the inlet and outlet of the valve body when the ball rotates relative to the valve seat. The valve body, valve seat and ball are all made of metal materials, and the ball and the valve The mating surfaces of the seat are respectively plasma sprayed with a ceramic layer.

The present invention also provides a production process for the above-mentioned hard-sealed ball valve. The process is as follows: when processing the sphere and the valve seat, respectively coat a ceramic material with a certain thickness on the mating surface of the sphere and the valve seat to form a ceramic layer, and then separately apply The matching surface of the ball and the valve seat is ground, and finally the ball and the valve seat are assembled and ground to make the ball and the valve seat hard-seal fit.

The beneficial effects of the present invention are: after the ceramic layer is plasma-sprayed on the metal base of the valve seat and the sphere, using the wear-resistant and anti-corrosion characteristics of the ceramic material, it can be used in harsh working conditions such as high wear, strong corrosion, high temperature, and high pressure. , can still guarantee the internal sealing performance and service life of the ball valve; at the same time, because the valve seat, ball and valve body are still made of metal, it can avoid the embrittlement of the valve seat and the ball. Since the ceramic material is sprayed onto the metal substrate of the valve seat and the ball by the plasma spraying process, the bonding strength between the ceramic layer and the metal substrate can be ensured and the ceramic layer can be prevented from falling off.

The production process of the hard-sealed ball valve provided by the present invention can ensure that after coating a certain thickness of wear-resistant and anti-corrosion material, the ball and the valve seat can meet the matching precision required by the hard seal, and the sealing performance of the hard-sealed ball valve can be improved.

The hard-sealed ball valve provided by the present invention can be mainly used in industrial fields such as electric power, petroleum, chemical industry, metallurgy, mining, sewage treatment, etc., especially in the face of severe working conditions such as high wear, strong corrosion, high temperature, and high pressure. Because of its excellent sealing performance and long service life, the performance-price ratio of ceramic-lined hard-sealed ball valves is far superior to other similar valves.

Description of drawings

Fig. 1 is a structural schematic diagram of a hard-sealed ball valve of the present invention.

The marks in the figure are: inlet 1, valve body 2, valve seat 3, ball 4, outlet 5, flow channel 6, and ceramic layer 7.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

A hard-sealed ball valve as shown in Figure 1, which includes a valve body 2 with at least one inlet 1 and an outlet 5, a valve seat 3 installed in the inner cavity of the valve body 2, and a ball 4 that is hard-sealed with the valve seat 3 , the sphere 4 is processed with a flow channel 6 that can selectively connect or disconnect the inlet 1 and outlet 5 of the valve body 2 when the sphere 4 rotates relative to the valve seat 3, the valve body 2, the valve seat 3 and the sphere 4 are all made of metal materials, and ceramic layers 7 are plasma-sprayed on the mating surfaces of the ball 4 and the valve seat 3 respectively. The technology of spraying ceramics with plasma spraying process is an existing technology, but it has never been used on hard-sealed ball valves before this application. The main reason is that there is a high hard-sealed fit between the ball and the valve seat of the existing ball valve. According to the production process of the existing ball valve, it is difficult to guarantee the matching accuracy between the ball and the valve seat after the ceramic layer is sprayed. Plasma spraying the ceramic layer on the seat, but only consider improving the wear resistance and corrosion resistance of the ball valve by changing the material of the ball and the valve seat. The innovation of the present invention lies in creatively applying the technology of spraying ceramics by the plasma spraying process to the hard-sealed ball valve, that is, the ceramic layer 7 is plasma sprayed on the mating surface of the ball 4 and the valve seat 3 respectively, and the ceramic layer 7 has Wear-resistant and anti-corrosion characteristics, in the face of high wear, strong corrosion, high temperature, high pressure and other harsh working conditions, it can still ensure the internal sealing performance and service life of the ball valve; at the same time, because the valve seat 3, the ball 4 and the valve body are still The use of metal can avoid the embrittlement of the valve seat 3 and the ball 4. Since the ceramic material is sprayed onto the metal substrate of the valve seat and the ball by the plasma spraying process, the bonding strength between the ceramic layer and the metal substrate can be guaranteed and the ceramic layer can be prevented from falling off. Probation shows that the hard-sealed ball valve of the present invention exhibits excellent sealing performance and super-long service life in the face of harsh working conditions such as high wear, strong corrosion, high temperature, and high pressure. At the same time, the performance-price ratio of the hard-sealed ball valve is far superior to other similar valves, so it has an extremely wide application space and good application prospects.

On the basis of the above solution, the entire outer spherical surface of the sphere 4 and the entire inner surface of the valve seat 3 are plasma-sprayed with a ceramic layer 7 . In this way, except for the matching surface on the ball 4 and the valve seat 3, all the surfaces in contact with the medium are plasma-sprayed with the ceramic layer 7, which further improves the wear resistance and corrosion resistance of the valve seat 3 and the ball 4. In addition, as shown in FIG. 1 , the inner wall of the flow channel 6 is also plasma sprayed with a ceramic layer 7 , and the inner wall of the valve body 2 is also plasma sprayed with a ceramic layer 7 . In this way, all surfaces in the entire ball valve in contact with the medium and the mating surfaces of the ball 4 and the valve seat 3 are plasma-sprayed with the ceramic layer 7, thereby ensuring the comprehensive performance of the entire ball valve.

Wherein, the ceramic material of each ceramic layer 7 is preferably aluminum oxide or chromium oxide. The above two materials have very high tensile strength, compressive strength, elastic modulus, hardness, etc., so they have extremely high wear resistance, corrosion resistance, and erosion resistance. Not only that, the above two materials also have good self-lubricating properties, so they can achieve good sealing performance.

The present invention also provides a production process of the above-mentioned hard-sealed ball valve. The feature of this process is that when the ball 4 and the valve seat 3 are processed, a certain thickness of ceramic material is plasma sprayed on the mating surface of the ball 4 and the valve seat 3 to form a ceramic layer 7, and then the ball 4 and the valve seat 3 are respectively The mating surface is ground, and finally the sphere 4 and the valve seat 3 are assembled and ground to make the sphere 4 and the valve seat 3 hard-tightly cooperate. Since the mating surface of the sphere 4 and the valve seat 3 is ground and the sphere 4 and the valve seat 3 are assembled and grinded together, the "counter-grinding" utilizes the relative movement between the sphere 4 and the valve seat 3. The friction of the contact surface is ground, so it can ensure the matching accuracy between the ball 4 and the valve seat 3 after coating a certain thickness of wear-resistant and anti-corrosion material, so as to meet the sealing requirements between the ball 4 and the valve seat 3. When performing plasma spraying, the ceramic material should be evenly sprayed onto the entire outer spherical surface of the sphere 4, the entire inner surface of the valve seat 3 on the inner wall of the flow channel 6, and plasma spraying is also performed on the inner cavity wall of the valve body 2, All surfaces in the entire ball valve that are in contact with the medium and the mating surfaces of the ball 4 and the valve seat 3 are plasma-sprayed with the ceramic layer 7, thereby ensuring the comprehensive performance of the entire ball valve.

Example

(1) The processing of spheroid 4, concrete steps are:

1. Clamp the blank, align it according to the channel hole of the sphere, and process the channel hole, taper surface and chamfer angle;

2. Taking the processed sphere channel as the positioning reference, the sphere is milled and processed. The finished sphere is smooth, the cleanliness is not lower than Ra1.6, the coaxiality is less than 0.05mm, and the out-of-roundness is less than 0.01mm;

3. Clamp the processed sphere on the fixture, and use a special concave spherical abrasive tool to process it with 60# single crystal corundum. 0.006mm;

4. Use the plasma spraying process to spray the ceramic layer 7 on the outer surface of the sphere and the flow channel of the sphere, the spraying thickness is 0.5mm, and the hardness is HRC90;

5. On the special fixture for clamping the sphere after spraying, use a special concave spherical abrasive tool for processing:

①Coarse grinding, the abrasive is M40 diamond powder, the finish after rough grinding is not less than Ra0.8, the coaxiality is less than 0.03mm, and the out-of-roundness is less than 0.004mm.

② Fine grinding, the abrasive is M15 diamond powder, the finish after fine grinding is not less than Ra0.2-0.4, the concentricity is less than 0.03mm, and the out-of-roundness is less than 0.004mm.

6. Grinding: The processed sphere is ground against the special concave spherical abrasive tool. The grinding powder is M15 and M5 respectively, and the out-of-roundness after processing should be less than 0.0025mm;

(2) The processing of the valve seat, the specific steps are:

1. The coaxiality between the spherical surface of the processed valve seat and the sphere is less than 0.03mm;

2. Use the plasma spraying process to spray ceramics on the spherical surface of the valve seat, the spraying thickness is 0.5mm, and the hardness is HRC90;

3. The valve seat after spraying is clamped on the fixture, and processed on the special convex spherical abrasive tool:

① Coarse grinding, the abrasive is M40 diamond powder, the finish after rough grinding is not less than Ra0.8,

② Fine grinding, the abrasive is M15 diamond powder, the finish after fine grinding is not less than Ra0.4,

4. Grinding: The processed valve seat is grinded with a special convex spherical abrasive tool, the grinding powder is M15, M5, and the smoothness after grinding is Ra0.2--0.4;

(3) The ball and the valve seat are oppositely ground, the specific steps are:

1. Carry out 2-3 times of manual grinding on the processed sphere and the spherical surface of the valve seat. The grinding liquid used is as follows:

①Use W40 diamond grinding paste to prepare grinding liquid, the grinding liquid is: glycerin + water, the ratio of grinding liquid is 1:1,

② Use W10 diamond grinding paste to configure the grinding liquid, the ratio is 22.4% of oil, 31.5% of mixed fat, 1.1% of kerosene,

③Use W5 diamond grinding paste to grind and prepare grinding liquid, the ratio is 22.4% grease, 31.5% mixed fat, 1.1% kerosene. After grinding, clean the ball and valve seat with cleaning liquid or 90# gasoline for 10-15 minutes.

In the above-mentioned embodiments, the special-purpose concave-spherical grinding tool and the special-purpose convex-spherical grinding tool mean that the contact surface between the grinding tool and the workpiece to be ground is a corresponding concave spherical or convex spherical shape, so as to ensure the grinding amount of each part of the space. uniform.

Claims (6)

1. hard seal ball valve, comprise the valve body (2) that is provided with at least one import (1) and outlet (5), be installed in the valve seat (3) in valve body (2) inner chamber, and the spheroid (4) that is sealed and matched firmly with valve seat (3), be processed with in the described spheroid (4) when spheroid (4) is selectable when valve seat (3) rotates relatively and make the import (1) of valve body (2) and export the runner (6) that (5) are communicated with or disconnect, described valve body (2), valve seat (3) and spheroid (4) are made by metallic material, it is characterized in that: plasma spray scribbles ceramic layer (7) respectively on the fitting surface of spheroid (4) and valve seat (3).

2. hard seal ball valve as claimed in claim 1 is characterized in that: the equal plasma spraying of total inner surface of the whole outer spherical surface of described spheroid (4) and valve seat (3) has ceramic layer (7).

3. hard seal ball valve as claimed in claim 1 is characterized in that: plasma spraying has ceramic layer (7) on the inwall of described runner (6).

4. hard seal ball valve as claimed in claim 1 is characterized in that: plasma spraying has ceramic layer (7) on the internal chamber wall of described valve body (2).

5. as claim 1,2,3 or 4 described hard seal ball valves, it is characterized in that: the stupalith of described each ceramic layer (7) adopts aluminium oxide or chromium oxide.

6. the production technology of the described hard seal ball valve of claim 1, when processing spheroid (4) and valve seat (3), the certain thickness stupalith of plasma spraying forms ceramic layer (7) on the fitting surface of spheroid (4) and valve seat (3) respectively, and then respectively the fitting surface of spheroid (4) with valve seat (3) ground, to grinding spheroid (4) and valve seat (3) are sealed and matched firmly spheroid (4) and valve seat (3) assembling back more at last.

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