JPH07100577A - Manufacture of ball for valve - Google Patents

Abstract

PURPOSE:To obtain a ball for a valve forming an engaging groove at the outer periphery in a simple process and at high yield. CONSTITUTION:A cylindrical blank 20 is press-formed to form a recessed part 21 at a part of the outer periphery. Successively, the blank 20 is sphered by cold-forging and the recessed part 21 is formed to the engaging groove 22. Therefore, as the formations of sphering and engaging groove 22 of the blank 20 are executed by plastic-working without machining, the product ball 23 is obtd. in the simple process at the high yield.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a ball incorporated in a valve for opening and closing a flow path.

[0002]

2. Description of the Related Art A valve for circulating or stopping circulation of a fluid is provided in the middle of a pipe. Various types of valves are used, but a valve is typically used to open and close the flow path. As shown in FIG. 1, this valve connects an upstream pipe 1 and a downstream pipe 2 with a valve casing 3. The ball 5 arranged on the valve seat 4 in the valve casing 3 has a substantially spherical contour, and the flow hole 6 penetrates through the central portion thereof. The tip of the drive shaft 9 that rotates by the operation of the lever 8 meshes with the engagement groove 7 formed in a part of the outer peripheral surface of the ball 5. In the state of FIG. 1, the flow hole 6 of the ball 5 extends in the direction perpendicular to the paper surface, and the flow path from the upstream pipe 1 to the downstream pipe 2 is blocked by the outer peripheral wall of the ball 5. When the ball 5 is rotated 90 degrees via the drive shaft 9 by operating the lever 8, the flow hole 6
Corresponds to the pipe axis direction of the upstream pipe 1 and the downstream pipe 2,
A flow path from the upstream pipe 1 to the downstream pipe 2 is opened.

This type of ball 5 has been manufactured by cutting a blank cut from a casting such as stainless steel. However, when the spherical processing, the formation of the flow hole 6 and the engagement groove 7 are all cut, the productivity is poor,
The cost of the product obtained is high. In addition, the ratio of materials used as products is extremely low, which may result in waste of resources.
Problems caused by cutting work are described in, for example, Japanese Patent Laid-Open No. 62-67
As disclosed in Japanese Patent No. 29, the problem is solved by cold forging the pipe material to manufacture the balls. In this method, as shown in FIG. 2, a cylindrical material 10 cut out from a pipe material is used. After finishing the end face of the cylindrical material 10, it is installed in a die of a cold forging machine. Cylindrical material 10
Is pressed in the axial direction of the pipe to form a semi-molded product 11 in which the peripheral wall of the material bulges outward. The outer periphery of the semi-molded product 11 is cut to a position indicated by a chain double-dashed line to obtain a finished ball product 12.
Next, a part of the periphery is removed by cutting to form a through hole to be the engaging portion 13, and the ball product 14 is obtained.

[0004]

When the cylindrical material 10 is cold forged into the ball product 14, the product yield is significantly improved as compared with the case of the conventional cutting process. However, in the step of finishing the peripheral surface of the semi-molded product 11 into a spherical shape and the step of forming the engaging portion 13, the cutting work is still required. In particular, when the engaging portion 13 is formed by cutting, the cutting work becomes difficult because the ball finished product 12 is work-hardened. In addition, defects such as cracks and cracks are likely to enter the ball product 14 with cutting. This type of defect is a fatal defect as a product that causes fluid leakage when a valve incorporating the ball product 14 is used in a piping system. In order to facilitate the cutting process, the work-hardened semi-molded product 11 and finished ball product 12 are subjected to solution heat treatment. Although the semi-molded product 11 and the finished ball product 12 are softened by the solution heat treatment, an extra step is added, resulting in an increase in man-hours for work and an increase in manufacturing cost.

When opening and closing the valve, the drive shaft 9
The ball 5 is rotated 90 degrees by the turning. At this time, the tip portion of the drive shaft 9, that is, the stem is pressed against the engagement groove 7. However, the engaging portion 13 formed by cutting has a small contact area with the stem and receives a large load locally. When the load is repeatedly applied, sagging occurs in the portion that contacts the stem. This tendency is particularly seen at the end of the engaging portion 13 and the like. As a result, there is backlash,
It will not be possible to open and close the valve smoothly. The present invention has been devised in order to solve such a problem, not by the cutting process that causes the reduction of the wall thickness, but by forming the product shape including the engaging groove by plastic working, the strength is improved. Also aims to produce excellent valve balls with high yield and high productivity.

[0006]

In order to achieve the object, the manufacturing method of the present invention comprises press-forming a recess serving as an engaging groove in a part of the peripheral surface of a blank cut from a pipe material, and then cold forging. It is characterized in that the blank is formed into a spherical shape. In the present invention, a cylindrical blank 20 cut into a predetermined length as shown in FIG. 3 is used as a material. The material of the blank 20 is not particularly limited, and various metal materials can be used. However, in consideration of corrosion resistance, strength and the like, it is preferable to use stainless steel such as SUS304 and 316. The blank 20 is press-molded to form a recess 21 on a part of the peripheral surface. Recess 21
In the state where the blank 20 is spheroidized by cold forging, becomes the engagement groove 22. The obtained product balls 23 are appropriately subjected to processing such as surface polishing and end surface finishing, but essentially no cutting processing for forming the main body is required. Since the engagement groove 22 is formed from the concave portion 21 by press working, the thickness reduction in the periphery thereof is suppressed, and rather the influence of thickening by cold forging appears strongly. Therefore, there is no corner where cracks are likely to occur, and the product has excellent strength. The engagement groove 22 has a large contact area with the stem and has sufficient deformation resistance against repeated load applied when the valve is opened and closed. Further, since it is also excellent in strength, it is possible to obtain a valve ball that is thinned accordingly.

[0007]

[Example] SU having an outer diameter of 60.5 mm and a wall thickness of 4.5 mm
From S304 stainless steel pipe, length 55.6mm
The blank 20 was cut out. A part of the peripheral surface of the blank 20 is pressed by a 15-ton press molding machine to form a recess 2 having an inner width of 7 mm.
1 was formed. The recess 21 had a radius of 22 mm and extended in the circumferential direction of the blank 20. In addition, the outer width of the peripheral wall defining the recess 21 was 15.5 mm. Next, the blank 20 having the recess 21 formed therein is cold-forged by a 90-ton press to produce a spherical product ball 23 having an outer diameter of 66.8 mm.
Molded into. Inside the product ball 23, the inner diameter of the opening is 3
Flow hole 24 with 6.5 mm and opening outer diameter 44.88 mm
Became. Distance L from one opening to the other
Was 48.4 mm. The inner width of the engagement groove 22 formed on the outer peripheral portion of the product ball 23 was slightly wider than that of the recess 21 by 10 mm.

When observing a cross section around the engagement groove 22 of the obtained product ball 23, the wall thickness of the blank 20 is 4.
The thickness was almost the same as 5 mm. It is considered that this is because the thinning around the recess 21 when the recess 21 was formed by press molding was offset by the gathering of the meat in the center during cold forging. Also, the engaging groove 2
No sharp corners were formed around No. 2. The product ball 23 has a sphericity improved by cutting, is subjected to surface polishing, end face finishing, and the like, and then is incorporated into a valve. Thus, since the ball body is formed by cold forging instead of cutting, the yield of using the material of the blank 20 as a ball is high. In addition, there were few thin-walled portions where stress concentration was likely to occur, and the pressure resistance of the ball was high. In the above embodiments, the case where a ball having an inner space having a substantially spherical shape is manufactured has been described. However, the present invention is not limited to this, and for example, it is possible to set a large forging rate and manufacture a ball in which meat is concentrated in the central portion. Such a ball has high pressure resistance and is suitable for a valve for high-pressure fluid.

[0009]

As described above, in the present invention, the concave portion which becomes the engaging groove is press-formed on a part of the peripheral surface of the cylindrical blank, and then the spherical shape is obtained by cold forging.
Therefore, the cutting process that wastefully consumes the material is significantly reduced, and the valve ball is manufactured with a high yield. The obtained ball has a large contact area of the engaging groove with the stem and a sufficient wall thickness, so that it is a product excellent in strength. Further, since the wall thickness can be reduced by the increase in strength, the weight of the ball can be reduced. Moreover, since the process itself is simple, the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 Ball-integrated valve

[Fig. 2] Conventional cold forging to manufacture a valve from a cylindrical material

FIG. 3 is a process diagram of manufacturing balls by press forming and cold forging according to the present invention.

[Explanation of symbols]

20: Cylindrical blank 21: Recess formed by press molding 22: Engagement groove 23: Product ball
24: Distribution hole

Claims (1)

[Claims] 1. A method of manufacturing a ball for a valve, which comprises press-forming a recess serving as an engaging groove in a part of a peripheral surface of a blank cut out from a pipe material, and then cold-forging the blank into a spherical shape. .