JP2642713B2 - Ball valve of piston pump for sand slurry transport - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a ball valve for a piston pump (hereinafter, a ball valve) used for a piston pump for flowing sand dredged in a dam or a river as a thriller. In particular, the present invention relates to a technique for preventing uneven wear of a spherical valve and preventing breakage and damage of a valve seat.

[Prior Art] In recent years, a piston pump has been attracting attention as means for transporting sand dredged from a dam or the like to a remote place, and FIG. 1 shows an example thereof.

The piston pump shown in FIG. 1 reciprocates a piston 2 provided in a cylinder 1 to suck up water containing sand and mud, that is, sand slurry, from an intake pipe 3 and introduce it into a drawing pipe 4. Is discharged into the transfer pipe 5, and two plate valves 6 are interposed at a branch portion of the water intake pipe 3, the drawing pipe 4, and the transfer pipe 5.

Here, as shown in FIG. 2, the plate valve 6 is movable vertically in a valve chamber 9 having an inlet 7 and an outlet 8 and is urged downward by a coil spring 10. A plate-shaped valve 11 is attached, and a ring-shaped valve seat 12 is fixed to the inner periphery of the suction port 7.
Reference numeral 11 denotes a disc-shaped valve body 13 and an elastic body fixed to the upper surface of the valve body 13 and in contact with the upper end of the valve seat 12 in a liquid-tight manner.
14, which opens and closes in accordance with the reciprocating movement of the piston 2, whereby the transfer pipe 5 does not flow backward.
It is designed to be discharged inside.

By the way, the plate valve 6 as described above is used when the concentration of the sand slurry is relatively low or when the particle diameter of the sand is small because the weight is small and the wear portion can be easily replaced. When the concentration is high and the particle size of the sand is large, a ball valve having a heavy movable part and a simple structure is used.

FIG. 3 shows an example of a conventional ball valve.
The point that a spherical valve 21 is arranged instead of the plate-shaped valve 11 is that a guide 24 which is a guide when the spherical valve 21 moves to the valve seat 23 side is arranged on the wall side facing the discharge port 22 side. The plate valve 6
Is different. Here, the spherical valve 21 is formed by welding two hemispherical shells to each other and welding each other, and by giving a hollow interior, an appropriate specific gravity is given.

[Problems to be Solved by the Invention] By the way, the sand slurry fed by the piston pump has extremely high abrasion, so that the life of the ball valve is remarkably reduced, and the sand slurry is stably fed. There was a problem that can not be.

That is, as the material of the spherical valve 21, conventionally, stainless steel, quenched alloy steel was used as the material of the valve seat 23, but the spherical slurry 21 is liable to cause uneven wear by the sand slurry,
In particular, wear tends to progress at the welded portion. For this reason, a gap is formed between the spherical valve 21 and the valve seat 23, and when the sand slurry having a high flow rate passes through the gap, local wear called V-shaped notch wear occurs on the surface of the valve seat 23, and the short gap is formed. It becomes unusable in a matter of hours.

Therefore, conventionally, it has been studied to form the spherical valve 21 and the valve seat 23 from, for example, ceramics having high wear resistance. However, in such a case, the spherical valve 21
Spherical valve 21 or valve seat 23 due to impact when hitting 23
Cracks occurred in the steel, and it was not completely usable.

Further, in order to buffer the impact of the spherical valve 21, the valve seat 23 is provided.
Fixing a cushion material such as rubber on the surface of the rubber was also studied, but it was not usable in any case because of insufficient bonding strength between rubber and the valve seat and insufficient strength of rubber itself.

[Purpose of the Invention] The present invention has been made in view of the above circumstances, and it is possible to prevent uneven wear of a spherical valve, as well as to prevent the valve seat from being cracked and damaged. It is an object to provide a ball valve which can be used.

[Means for Solving the Problems] In the ball valve of the present invention, the spherical valve is made of Celax, and the valve seat has a higher tensile strength than the spherical valve, and has a hardness of Hs75 or more and is higher than the hardness of the spherical valve. It is made of low alloy steel.

Here, the material of the valve seat is not limited at all, but it is preferable that the valve seat be made of nickel chromium molybdenum steel having excellent toughness.

[Action] In general, it is well known that ceramics have extremely high hardness and are selected for wear resistance. However, when a spherical valve is made of ceramics, a valve seat that repeatedly collides with the ceramic is required. How to configure it has not yet been resolved.

That is, when the hardness of the alloy steel is increased, the toughness such as the tensile strength decreases, and when the toughness is increased, the hardness decreases. Therefore, if the hardness of the valve seat is increased,
It is easily damaged by the impact of a hard ceramic spherical valve. On the other hand, when the toughness of the valve seat is increased to prevent damage due to collision, the hardness is low, so that the valve slurry is severely rubbed by the printing slurry and easily worn. However, even in the case of alloy steel, by setting the hardness and tensile strength within a predetermined range, it has abrasion resistance enough to withstand rubbing with sand slurry, and so as not to be damaged even if repeatedly subjected to impact force. Should be able to.

Therefore, the present inventors have conducted intensive research from the above viewpoint, and as a result, it has been found that the tensile strength is higher than ceramics, the hardness is lower than ceramics, and Hs75 or more, it can sufficiently withstand use as a valve seat for sand slurry. I found it. That is, in the ball valve of the present invention, since the tensile strength of the valve seat is higher than that of the spherical valve and the hardness is lower than that of the spherical valve, it is possible to obtain sufficient toughness not to be damaged by repeated impact forces, and to increase the hardness. Since the Hs is 75 or more, it is possible to obtain abrasion resistance that does not easily wear even when rubbed by the sand slurry.

Improving the wear resistance of the spherical valve and the valve seat leads to the prevention of uneven wear at the contact surfaces thereof, and therefore, the V-type notch wear, which has conventionally significantly reduced the life of the ball valve, has been reduced. It is possible to prevent the occurrence of so-called local wear.

In particular, the toughness of the valve seat can be further increased by using nickel chrome molybdenum steel as the material of the valve seat,
The occurrence of crack breakage in the valve seat can be effectively prevented.
Further, since the occurrence of crack breakage is small, the hardness of the valve seat by the heat treatment can be set to an optimum value for use in a piston pump for sand slurry, and the wear resistance of the valve seat can be further improved. .

Example An example of the present invention will be described below with reference to FIGS. 3 and 4.

In the ball valve of this embodiment, the spherical valve 21 is made of ceramics, preferably alumina, and the valve seat 23 is made of nickel chromium molybdenum steel (SNCM39). In addition, as the material of the valve seat 23, a material having high toughness such as chromium molybdenum steel is appropriately used. Here, the spherical valve 21 is different from a conventional hollow valve and is formed as a solid unitary body. This is because the specific gravity of alumina is 3.
Because it is as small as about 9, it is not necessary to adjust the specific gravity of the spherical valve 21 by making the inside hollow.

On the other hand, the valve seat 23 has a surface subjected to induction hardening, and has a tensile strength higher than that of the spherical valve 21 and a hardness lower than the hardness of the spherical valve 21 and Hs75 or more. As the heat treatment method for the valve seat 23, water quenching, oil quenching, or the like may be appropriately employed.

In such a ball valve, since the spherical valve 21 is made of ceramic having high wear resistance, the wear resistance can be improved and uneven wear can be prevented. , The tensile strength of the valve seat 23 is a spherical valve
Since the hardness is lower than that of the spherical valve 21 and that of the spherical valve 21, the toughness of the valve seat 23 is high, and therefore, the valve seat 23 is not damaged by repeated impact force.

That is, as the spherical valve 21 and the valve seat 23 wear, as shown in FIG. 4, the contact angle θ between the spherical valve 21 and the valve seat 23 increases, and as a result, the impact force by the spherical valve 21 increases. It acts on the valve seat 23 as a bending force. However, since the toughness of the valve seat 23 is high, it is possible to sufficiently withstand the bending force.

Further, since the hardness of the valve seat 23 is Hs75 or more, wear resistance that does not easily wear even when rubbed by sand slurry can be obtained, and the wear resistance of the spherical valve 21 and the valve seat 23 is improved. Thereby, uneven wear on those contact surfaces can be prevented. Therefore, it is possible to prevent the occurrence of local wear called V-shaped notch wear, which has conventionally greatly reduced the life of the ball valve, and it is possible to greatly improve the life of the ball valve.

In particular, since the material of the valve seat 23 is nickel chrome molybdenum steel, the toughness of the valve seat 23 is greatly improved,
It is possible to effectively prevent the occurrence of crack breakage. Further, since the occurrence of crack breakage is small, the hardness of the valve seat 23 by the heat treatment can be set to an optimum value by using the piston pop for sand slurry, and the wear resistance of the valve seat 23 can be further improved. it can.

Further, in the above-mentioned ball valve, since the spherical valve 21 is integrally formed, there is no uneven wear in the welded portion unlike the conventional case, and this point is also a factor for improving the life of the ball valve.

Next, the present invention will be further clarified with reference to specific experimental examples. Table 1 shows the amount of wear of the spherical valve 21 when sand slurry is fed by a piston pump using the above-mentioned ball valve. It is shown.

As can be seen from Table 1, the wear amount of the spherical valve 21 is 135 g, and the conventional stainless steel (SUS440) used under the same conditions
It was about half as compared with the product made in Japan. Further, the valve seat 23 did not undergo any V-shaped notch wear at the contact portion with the spherical valve 21, and was uniformly worn as a whole, without cracking or chipping.

As described above, in the ball valve described above, the wear resistance of the spherical valve 21 and the valve seat 23 can be improved without causing cracking and breakage in the valve seat 23. Therefore, the bias between the spherical valve 21 and the valve seat 23 can be improved. Wear was prevented, and the life was greatly improved.

[Effects of the Invention] As described above, in the ball valve of the present invention, the spherical valve is made of ceramics, the valve seat has a higher tensile strength than the spherical valve, and the hardness is Hs75 or more, and the hardness is higher than that of the spherical valve. Is made of a low alloy steel, so that the wear resistance of the spherical valve can be improved and its uneven wear can be prevented, as well as the impact force that the valve seat repeatedly receives from the spherical valve. There is no breakage, and the wear resistance of the valve seat can be improved.

Therefore, uneven wear on the contact surfaces of the spherical valve and the valve seat can be prevented, and the occurrence of local wear called V-shaped notch wear, which has conventionally significantly reduced the life of the ball valve, can be prevented. Can be greatly improved.

Further, by using nickel chromium molybdenum steel as the material of the valve seat, the toughness of the valve seat can be further increased, and the occurrence of crack breakage of the valve seat can be effectively prevented. Further, since the occurrence of crack breakage is small, the hardness of the valve seat by the heat treatment can be set to an optimum value for use in a piston pump for sand slurry, and the wear resistance of the valve seat can be further improved. .

[Brief description of the drawings]

1 is a side view showing a piston pump using a conventional ball valve, FIG. 2 is a side sectional view showing a conventional plate valve, FIG. 3 is a side sectional view showing a conventional ball valve,
FIG. 4 is a sectional view taken along line IV-IV of FIG. 21: Spherical valve, 22: Discharge port, 23: Valve seat.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tohru Ujuku 2-4-1 Hamamatsucho, Minato-ku, Tokyo Inside Mitsubishi Metals Co., Ltd. Tokyo Branch (72) Inventor Tamotsu Shimizu 2-4-2 Hamamatsucho, Minato-ku, Tokyo No. 1 In the Tokyo branch of Mitsubishi Metals Corporation (72) Inventor Masayuki Naoki 985-1, Ginya, Ikuno-cho, Asago-gun, Hyogo Prefecture Inside the Ikuno Factory of Mitsubishi Metals Corporation (56) References JP-A-60-81581 (JP, A JP-A-58-178812 (JP, A) JP-A-57-177467 (JP, A) JP-A-50-86733 (JP, U) JP-B-47-20773 (JP, B1)

Claims (2)

(57) [Claims] A spherical valve is disposed in a valve chamber having a suction port and a discharge port, a valve seat is provided at the suction port, and the spherical valve is brought into contact with the valve seat in a liquid-tight manner, so that a fluid flows. In the ball valve of the sand slurry transport pump configured to prevent the gas from flowing out of the valve chamber from the suction port, the spherical valve is formed of ceramics, and the valve seat has a higher tensile strength than the spherical valve. , And hardness is Hs75
A ball valve for a piston pump for transporting sand slurry, wherein the ball valve is made of an alloy steel having a hardness lower than that of the spherical valve. 2. The ball valve of a piston pump for transporting sand slurry according to claim 1, wherein said valve seat is made of nickel chromium molybdenum steel.