JPH0510186B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a vertical centrifugal casting mold, and more specifically, when centrifugally casting a ball for a ball valve, a mold that is attached to the ball after centrifugal casting is used. This invention relates to a vertical centrifugal casting mold that is grooved with specific means for positioning the stem.

(Prior art) Centrifugal force casting involves injecting molten metal into a rotating mold (metal mold), forming it while applying centrifugal force, and
This is a casting method that involves solidification, and in addition to the general horizontal centrifugal casting method, there is also a vertical centrifugal casting method in which the rotation axis of the mold is vertical.

The vertical centrifugal casting method is more suitable for casting irregularly shaped products than the horizontal centrifugal casting method, and is used to manufacture tapered sleeves, valve flow control valves, balls for ball valves, etc.

By the way, when manufacturing balls for ball valves (hereinafter referred to as "balls") using the vertical centrifugal casting method, as shown in FIG. Since it is necessary to form a groove and attach the stem, it is necessary to create a recess in the core and cast the area where the stem groove will be formed thickly in advance. After casting, a center position is determined using a punch or the like on this thick wall portion for machining the stem groove.

The conventional method for positioning a stem punch has been based on an ultrasonic method. In this method, as shown in FIG. 5, the thick part 2 of the ball 1 after vertical centrifugal casting is
To determine the stem punch position, move the ultrasonic probe 3 around the outer periphery of the ball 1 to find the position where the echo changes, and find the midpoint l between the positions of the two R parts at both ends of the thick part 2. (l/2) is defined as the stem punch position 4, and this position is clearly indicated by the punch. However, with this method,
There is not necessarily a clear discontinuity point in the R sections at both ends of the thick section 2, and there is also a difference in shape between the left and right R sections, making it difficult to perform ultrasonic detection with high accuracy, resulting in a lack of reliability. There was a problem. Therefore, there is no guarantee that the stem groove 5 formed based on this position 4 is also accurately centered. Therefore, in extreme cases, when forming the stem groove, the stem groove is often machined at a position shifted from the thick wall part 2, and the stem groove often comes off inside the ball 1, which is a problem. Ta.

(Object of the Invention) The present invention has been made in order to solve the above-mentioned problems regarding the positioning of the stem center of a vertical centrifugal casting ball. The object of the present invention is to provide a mold for centrifugal casting.

(Structure of the Invention) In order to achieve the above object, the present inventors conducted intensive research on the structure of a vertical centrifugal casting mold for manufacturing balls, and found that the structure of a mold used for this type of vertical centrifugal casting was In the design, we focused on the point that the partition line between the upper mold and the lower mold is provided at the height of the center position of the centrifugally cast product (ball) to be obtained. As a result of further consideration considering that the part of the thick part of the ball where the stem groove is to be machined will be removed after casting, we came up with the idea of casting a pin into the part of the thick part of the ball where the stem groove is to be machined, and created a vertical shape for this purpose. The present invention provides a specific configuration of a centrifugal casting mold.

That is, in a vertical centrifugal casting mold for manufacturing balls, a pin is arranged in the main mold along the partition line between the upper mold and the lower mold, and this pin protrudes toward the recess for the stem groove provided in the core. This is how it was done.

A ball for a ball valve obtained by vertical centrifugal casting using a mold with such a configuration has a pin cast into it, and after casting, the outer protrusion of this pin is cut off along the outer surface of the ball. According to
The cross section of the pin can be exposed. This pin position corresponds to the ball's stem center position and is clearly indicated, so the stem groove forming process can be performed based on this position, and the remaining part of the pin will be removed by this process and there will be no damage to the ball product. No problem.

The shape and dimensions of the pin to be cast can be selected as appropriate, taking into account thermal and physical deformation during casting, relationship with the stem center position, etc., and the material can also be selected.
Materials such as SS materials can be selected as appropriate.

The present invention will be explained in detail below based on illustrated embodiments.

(Example) Fig. 1 is a sectional view schematically showing an embodiment of a vertical centrifugal casting mold for manufacturing balls according to the present invention, and Fig. 2 is a partially enlarged view of the mold shown in Fig. 1. FIG.

The vertical centrifugal casting mold is, as shown in Figure 1,
A core 8 is disposed within a hollow portion of a main mold 7 consisting of an upper mold 7a and a lower mold 7b. Upper mold 7a and lower mold 7b
has an inner surface corresponding to the outer shape of the ball 1 to be cast (FIG. 3), and is held together by a partition line 9 and held by a suitable outer frame (not shown).

The core 8 is placed at a predetermined position on its outer periphery, that is,
In order to cast the stem groove forming part of the ball obtained by centrifugal casting into the thick wall part, a recessed part of a desired size is provided, and the position of this recessed part corresponds to the position of the pin 10 to be cast.
It is arranged in the hollow part of the main mold 7 so as to correspond to the ball thickness, and a space corresponding to the thickness of the ball is formed on the inner surface of the main mold.

The aforementioned pin 10 is fitted into the upper die 7a and/or the lower die 7b side along the partition line 9, as shown in detail in FIG. By making it protrude, it is possible to use it as a casting.

A mold having such a configuration is used for casting with a vertical centrifugal casting device (not shown) to manufacture a ball valve made of SCS13 or the like. As partially shown in FIG. 3, the resulting ball has a pin 10 cast into the thick wall portion 2 at the location where the stem groove 5 is to be formed. After casting, the protruding portion of the pin 10 is cut off to expose its cross section, and the stem groove 5 is machined, but the remainder of the pin 10 is completely removed by this process. The stem can then be attached.

(Effects of the Invention) As detailed above, according to the present invention, during vertical centrifugal casting of balls for ball valves, a pin is provided as a reference for forming a stem groove on the ball after casting. Since a mold can be used, there is no need for stem center position detection or processing, which is complicated and difficult to expect accuracy as in the past, and can be easily done by simply cutting off the protruding part of the cast pin after casting. The stem center position can be clearly indicated with high precision, and the causes of yield decline such as stem grooves coming out due to stem center misalignment can be eliminated, so ball valve manufacturing and assembly can be done quickly, accurately, and economically. is extremely large.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view schematically showing a vertical centrifugal casting mold according to an embodiment of the present invention, FIG. 2 is a partially enlarged cross-sectional view of the mold shown in FIG. 1, and FIG. A partially enlarged cross-sectional view of a ball for a ball valve manufactured using a vertical centrifugal casting mold, Fig. 4 is a perspective view of a ball for a ball valve, and Fig. 5 shows the detection of the stem center position of the ball using an ultrasonic method. FIG. 2 is a diagram illustrating a conventional method of 1...Ball for ball valve, 2...Thick wall part,
3... Probe, 5... Stem groove, 7... Main mold, 7
a... Upper mold, 7b... Lower mold, 8... Core, 9...
Partition line, 10...pin.

Claims (1)

[Claims] 1. In a vertical centrifugal casting mold for manufacturing balls for ball valves, in which a core is placed in the hollow part of a main mold consisting of an upper mold and a lower mold, a partition line between the upper mold and the lower mold is A vertical centrifugal casting mold, characterized in that a stem center positioning pin is disposed on the main mold so as to extend along the core and protrude toward the stem groove recess formed in the core.