JP2000055216A - Molding method for ball valve ball - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the dimension and the accuracy for a ball valve ball without any extra additional machining by molding a spherical part by rolling from a pipe material and by molding a ball valve ball. SOLUTION: Chamfer parts are formed in inside ends in both sides of a material formed by machining a stainless steel metal into a pipe so as to facilitate the molding of a bore part 3. Secondly, the material is set in the inside of a die 5 having a spherical face 4 in the internal circumference provided in a ring rolling machine and a mandrel 6 is provided in the internal circumferential position of the material. The ring rolling machine is driven, the mandrel 6 is revolved with rotation, at the same time upper/lower dies 5 are rolling machined while pressurizing in the opposite direction, and a ball 2 having a center-recessed internal circumferential spherical face 2a is pressurizedly molded into a shape along the internal spherical face 4 and the mandrel sphere part 7. This constitution can provide a prescribed circularity only by the molding by rolling and provide the dimension and the accuracy as the ball valve ball.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a ball for a ball valve for forming a ball for a ball valve by rolling.

[0002]

2. Description of the Related Art A ball valve of this type is a fluid control valve for rotating a ball (valve element) having an opening inside a body to open and close a flow path and for controlling a flow rate by an intermediate opening. Various types of ball structures are known, and among them, a so-called hollow ball is conventionally used as a ball characterized by light weight.

[0003] By the way, as a typical method of forming the ball, there are known a method of casting and a method of pressing a material such as a pipe.

[0004]

However, the casting method tends to form a cavity due to bubbles such as gas.
Defects due to these cavities are often found after machining, which wastes material and processing time. Also,
In the case of casting, it is necessary to increase the wall thickness due to molten metal flow and shape instability, and there is a problem that the material and processing time are wasted accordingly. After casting, processing such as diameter processing, outer diameter roughing / finishing processing, and diameter chamfering is performed to complete the spherical portion of the ball for a ball valve.

[0005] In addition, in the forming method by pressing, as in the case of the casting described above, in order to secure a predetermined surface roughness and sphericity, it is necessary to perform processing such as diameter processing, outer shape roughening / finishing processing and diameter chamfering after molding. Met. Therefore, it is necessary to secure a cutting allowance and a diameter machining allowance for the material, and the material is wasted, and the thickness of the spherical portion becomes unbalanced near the diameter portion and becomes thicker. Since it is necessary to secure an anticipated amount of material, there is a problem that material costs are wasted.

[0006] The present invention is a method of forming a ball for a ball valve developed to solve the conventional problems. The object of the present invention is to eliminate the need for extra machining after forming a ball diameter portion. An object of the present invention is to obtain dimensions and precision as a ball for a ball valve.

[0007]

In order to achieve the above object, according to the present invention, a spherical portion is formed from a pipe-like material by rolling to form a ball for a ball valve.

[0008] In this case, it is preferable to form the bore portion by rolling at the same time as the spherical portion.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a method for forming a ball for a ball valve according to the present invention will be specifically described with reference to FIGS. As shown in FIG.
A material 1 is prepared by cutting a metal pipe made of blue brass, steel, aluminum, or the like into an appropriate length, or processing a metal into a pipe shape. Next, as shown in FIG. 2B, a chamfered portion 1a is formed at the inner ends of both ends of the material 1 as appropriate according to the implementation, and the diameter portion 3 of the ball 2 formed by rolling as described later.
Is easy to mold. The material 1 is desirably a pipe-shaped cylindrical shape, but is not limited to a pipe shape as long as it is a hollow shape having an inner diameter into which a mandrel can be inserted.

Next, as shown in FIG. 1 (c), the above-described material 1 is set inside a mold 5 having a spherical surface 4 on the inner periphery provided in the ring rolling machine. In this state, the mandrel 6 provided to revolve while rotating by the driving of the ring rolling machine is provided at the inner peripheral position of the material 1, and the ring rolling machine is driven to revolve while rotating the mandrel 6 at the same time. When the upper and lower molds 5 are rolled while being pressed in the direction of the opposing surfaces, as shown in FIG. 2, the ball 2 having the inner peripheral spherical surface 2a having a middle concave shape is formed by pressure. Ball 2
Is formed into a shape along the inner spherical surface 4 and the mandrel spherical portion 7, so that a predetermined sphere diameter and roundness can be obtained with high accuracy, and a smooth surface can be obtained by plastic deformation of the material.

According to the rolling process according to this embodiment, the spherical shape and roundness of the spherical portion 10 required for the ball for a ball valve can be obtained only by the rolling process, and the surface roughness close to a mirror surface can be obtained. . Therefore, a ball for a ball valve can be obtained without the need for outer diameter cutting after the formation of the spherical portion.

The mandrel 6 has a spherical portion 7 having a spherical diameter substantially the same as that of the mold 5 and a portion 3 between the spherical portion 7 and the rotating shafts 8 at both ends. And a spherical portion 10 of the ball 2 provided with a bore forming portion 9 for rolling
At the same time, the bore 3 is provided so as to be formed by rolling. There is no need to cut the outer end part by post-processing.

Incidentally, in order to form the arc portion 12 at the outer end of the diameter portions 3 and 3 of the ball 2, an arc-shaped portion may be provided at the outer end portions at both inner peripheral ends of the mold 5.

Further, as shown in FIG.
A stem joining portion 11 such as a groove or a hole for stem joining is provided on the upper portion of the ball 2, and then the spherical portion 10 is ground to finish the ball 2. In addition to the example in which the stem joint portion 11 is formed, a stem (not shown) may be directly welded or bonded to the upper surface of the ball 2.

Next, the operation of the above embodiment will be described.
As described above, when the ring rolling machine is driven at an appropriate rotation speed and feed speed to rotate the mandrel 6,
A predetermined spherical portion 10 having a hollow shape is formed from the pipe-shaped material 1 by rolling, and the forming process can be significantly shortened as compared with the conventional method.

By this rolling, the ball 2 is formed.
The ball 2 having a sphere diameter, a surface roughness and a roundness can be accurately and reliably molded in a short period of time without generating chips, and unlike conventional various ball molding methods, a reasonable ratio is obtained. It can be molded by a molding method.

In the above example, the case where the ball is formed into a spherical shape has been described, but the present invention is not limited to this.
Even a cylindrical shape having arcuate surfaces at both ends or another ball shape can be formed by the molding method of the present invention. In this case, a mold shape corresponding to the ball shape and a ball shape are formed. Is formed into a mandrel of a corresponding shape and rolled.

[0018]

As is apparent from the above, according to the present invention, no additional processing is required after forming the spherical portion,
Dimensions and precision as a ball for a ball valve can be obtained.

More specifically, since there is no defect such as a casting cavity and the like, a good yield can be formed, and a predetermined surface roughness or roundness can be obtained only by forming by rolling, the ball as a ball for a ball valve can be obtained. Dimensions and accuracy can be obtained.

Further, when the bore portion is formed by rolling at the same time as the spherical portion, it is not necessary to separately perform bore processing and bore chamfering. In addition, a ball valve ball having a uniform thickness can be obtained without the thickness of the spherical portion being biased toward the diameter portion, and it is not necessary to secure an extra material amount.

Further, by the method of forming by rolling, the surface of the central concave portion of the ball can have the same fine surface roughness as the outer surface of the ball, and the fluid resistance can be reduced. There is.

[Brief description of the drawings]

1 (a), 1 (b), 1 (c) and 1 (d) are explanatory views showing an example of a method for forming a ball for a ball valve according to the present invention.

FIG. 2 is a sectional view showing an example of the rolling process in FIG.

FIG. 3 is a perspective view of a ball formed by a forming method according to the present invention.

[Explanation of symbols]

 1 Material 2 Ball 3 Caliber 7 Spherical part

Claims (2)

[Claims] 1. A method for forming a ball for a ball valve, comprising forming a spherical portion by rolling from a material such as a pipe. 2. The method for forming a ball for a ball valve according to claim 1, wherein the diameter portion is formed by rolling at the same time as the spherical portion.