Centrifugal casting mold for ball body of large-diameter ball valve

Abstract

The centrifugal casting mold comprises a first half mold and a second half mold, an inner cavity of the first half mold and an inner cavity of the second half mold are spliced to form a ball casting cavity, and a spherical inner core is arranged in the ball casting cavity; the ball valve is characterized in that the spherical inner core adopts a hollow ball structure formed by connecting an outer cylindrical surface of a straight cylinder with a spherical surface, so that under the condition of ensuring the pressure resistance of the ball, the weight can be greatly reduced, the rotating torque of the ball in the ball valve is reduced, the configuration cost of an actuator is reduced, the bearing pressure of the ball valve on a pipeline system is reduced, and the use performance of the ball is greatly improved; the method is particularly suitable for casting of large-diameter balls.

Description

Technical Field

[0001] The invention relates to a centrifugal casting mold and process for a ball valve sphere, and in particular to a centrifugal casting mold and process for a liner core sphere. The invention is suitable for manufacturing a large-caliber ball valve sphere. Background Art

[0002] The ball is one of the key components of the ball valve. The ball cast by centrifugal casting has the advantages of environmentally friendly production process, ball density, low material loss in the production process, and low product manufacturing cost. For example, the patent number CN202411041647.9 applied by our company is "Centrifugal casting mold and process for liner inner core ball for ball valve". A spherical inner core is set in the spherical inner cavity of the inner mold, and the molten steel is centrifugally cast on the surface of the spherical inner core to form a spherical blank. The spherical inner core is made of low-cost materials such as ceramics and cast iron, so that the ball has both high performance requirements for use in special working conditions and can greatly reduce precious metal materials, reduce product costs, and save money and reduce costs. However, the main disadvantages of this centrifugal casting mold are: the spherical inner core adopts a solid structure, which makes the ball heavy, the material consumption is large, and the manufacturing cost is high; especially the large-diameter ball, which is very heavy, resulting in a large torque when the ball valve rotates in the ball valve, and the configuration power of the actuator is correspondingly increased, which greatly increases the cost of the ball valve product and creates a great load-bearing pressure on the installation pipeline system. Summary of the invention

[0003] The purpose of the present invention is to address the shortcomings of the prior art and provide a centrifugal casting mold for a large-diameter ball valve ball in which a hollow spherical inner core is arranged in the spherical inner cavity of the mold, which can greatly reduce the weight of the ball, reduce consumables and costs, reduce the rotational torque of the ball in the ball valve, greatly reduce the configuration power of the ball valve actuator, and reduce the load-bearing pressure of the ball valve on the installation pipeline system.

[0004] The centrifugal casting mold for realizing the object of the present invention is: A centrifugal casting mold for a large-caliber ball valve ball, comprising a first half mold and a second half mold, wherein the inner cavities of the first half mold and the second half mold are spliced ​​to form a ball casting cavity, wherein the ball casting cavity has a spherical inner cavity identical to the outer spherical surface of a ball blank, and a spherical inner core is arranged in the ball casting cavity; at least two radial positioning rods are arranged on the outer spherical surface of the spherical inner core, and the radial positioning rods are fixedly installed in radial positioning holes on the inner wall of the spherical inner cavity formed between the first half mold and the second half mold; the spherical inner core has a central through hole, and the diameter of the central through hole is larger than the diameter of the ball The diameter of the channel hole of the body blank is determined, and an annular casting cavity is formed between the outer spherical surface of the spherical inner core and the inner cavity wall of the spherical casting cavity, and the annular casting cavity is connected with the casting hole; its characteristic is that: the spherical inner core adopts a spherical surface sealed and welded on the outer cylindrical surface of the straight cylinder to form a spherical inner core with a hollow cavity, the radial positioning rod is fixedly welded on the radial outer spherical surface of the spherical surface perpendicular to the center line of the straight cylinder, and a radial exhaust pipe is arranged on the inner hole wall of the straight cylinder, one end of the radial exhaust pipe is connected with the hollow cavity of the spherical inner core, and the other end radially extends to the center line of the straight cylinder.

[0005] In the above technical solution, a plurality of radial through holes connecting the central through hole and the annular casting cavity are provided on the spherical inner core, and the radial through holes are sealed and isolated from the hollow cavity of the spherical inner core.

[0006] In the above technical solution, the outer spherical surface of the spherical inner core is provided with an axial hole casting cavity, the inner cavity wall of the spherical casting cavity is provided with an axial hole casting rod, the lower end of the axial hole casting rod is sleeved on the inner side of the axial hole casting cavity, and there is a gap between the outer peripheral surface of the axial hole casting rod and the inner wall of the axial hole casting cavity.

[0007] Compared with the prior art, the beneficial effect of the present invention is that the spherical inner core adopts a hollow sphere structure, so that a hollow structure is formed between the channel hole of the sphere and the spherical surface. While ensuring the pressure resistance of the sphere, the weight can be greatly reduced, the material consumption can be reduced, the manufacturing cost of the sphere and the rotational torque in the ball valve and the actuator configuration cost can be reduced, the load-bearing load of the ball valve on the pipeline system can be reduced, and the installation and use performance of the sphere can be greatly improved, especially for large-diameter spheres above 300mm, the cost reduction and the improvement of installation and use performance are very significant. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a structural cross-sectional view of the present invention.

[0009] Figure 2 The present invention Figure 1 Structural cross-sectional view of the middle spherical inner core.

[0010] Figure 3 The present invention Figure 2 Structural cross-sectional view along the BB direction.

[0011] Figure 4The present invention Figure 1 Left view of the second half of the mold.

[0012] Figure 5 The present invention Figure 4 Structural cross-section view along the AA direction.

[0013] In the figure: 1 first half mold, 2 second half mold, 3 spherical inner core, 4 radial exhaust pipe, 5 sphere casting cavity, 6 casting hole, 7 hollow cavity, 8 annular casting cavity, 9 axial hole casting rod, 10 axial hole casting cavity, 11 center through hole, 12 centrifuge turntable, 13 radial positioning groove, 14 straight cylinder, 15 spherical surface, 16 radial positioning rod, 17 radial through hole, 18 radial positioning hole, 19 center exhaust hole, 20 hollow circular tube. DETAILED DESCRIPTION

[0014] like Figure 1The centrifugal casting mold of the large-diameter ball valve ball shown in the figure comprises a first half mold 1 and a second half mold 2. The inner cavities of the first half mold 1 and the second half mold 2 are spliced ​​to form a ball casting cavity 5. The ball casting cavity 5 is connected to a casting hole 6 at the center of the right end surface of the second half mold 2. The first half mold 1 and the second half mold 2 are fixedly connected by a left half mold and a right half mold structure through a locking device, and are integrally fixedly installed on a centrifuge turntable 12. The ball casting cavity 5 has a spherical inner cavity that is the same as the outer spherical surface of the ball blank. A spherical inner core 3 is arranged in the ball casting cavity 5. The spherical inner core 3 is made of low-value metal material to reduce the use of precious metal material molten steel and reduce the manufacturing cost of the ball; at least one of the outer spherical surfaces of the spherical inner core 3 is provided. There are two radial positioning rods 16, which are fixedly installed in radial positioning holes 18 on the inner wall of the spherical inner cavity formed between the first half mold 1 and the second half mold 2, and the spherical inner core 3 is fixedly installed in the spherical casting cavity 5 to prevent the spherical inner core 3 from swinging under the action of centrifugal force during the casting process; the spherical inner core 3 has a central through hole 11, and the diameter of the central through hole 11 is larger than the channel diameter of the spherical blank. An annular casting cavity 8 is formed between the outer spherical surface of the spherical inner core 3 and the inner cavity wall of the spherical casting cavity 5, and the annular casting cavity 8 is connected with the casting hole 6. Molten steel is injected into the spherical casting cavity 5 through the casting hole 6. Under the action of centrifugal force, the molten steel wraps around the surface of the spherical inner core 3 to form a spherical The radial thickness of the annular casting cavity 8 is designed according to the working pressure of the sphere. Under the condition of reliably bearing the working pressure, the smaller the radial thickness of the annular casting cavity 8, the greater the cost saving effect. The lower limit of the radial thickness of the annular casting cavity 8 shall not be less than the wall thickness of the valve body; its characteristics are: the spherical inner core 3 adopts a hollow spherical structure, and the hollow spherical structure is composed of the outer cylindrical surface of the straight cylinder 14 connected to the spherical surface 15, and there is a hollow cavity 7 between the outer cylindrical surface of the straight cylinder 14 and the inner wall of the spherical surface 15, and the radial positioning rod 16 is fixedly connected to the outer spherical surface of the spherical surface 15, and the radial positioning rod 16 is arranged along the radial direction of the spherical surface 15 and perpendicular to the center line direction of the straight cylinder 14, and the straight cylinder 14 and the spherical surface 15 are formed by pressing iron plates and then sealed and welded to each other, and the radial positioning rod 16 is welded to the outer spherical surface of the spherical surface 15; a radial exhaust pipe 4 is arranged on the inner hole wall of the straight cylinder 14, and the radial exhaust pipe 4 has a central exhaust hole 19, one end of which is connected to the hollow cavity 7 of the spherical inner core 3, and the other end radially extends to the center line of the straight cylinder 14. During the casting process, the molten steel is radially thrown out along the central through hole 11 of the straight cylinder 14 under the action of centrifugal force, so that a cavity is formed in the center of the straight cylinder 14, and the gas in the hollow cavity 7 is discharged to the central through hole 11 of the straight cylinder 14 through the radial exhaust pipe 4, so as to prevent the gas in the hollow cavity 7 from expanding at high temperature to produce ultra-high pressure, which may cause the spherical inner core 3 to burst and cause a safety accident.

[0015] A plurality of radial through holes 17 connecting the central through hole 11 and the annular casting cavity 8 are provided on the spherical inner core 3. During the casting process, the molten steel can flow into the annular casting cavity 8 through the radial through holes 17 under the action of centrifugal force, thereby improving the flow performance of the molten steel. The radial through holes 17 are formed by welding a hollow circular tube 20 between the straight cylinder 14 and the spherical surface 15, thereby sealing and isolating the hollow cavity 7 of the spherical inner core 3 from the radial through holes 17 to prevent the molten steel from leaking into the hollow cavity 7.

[0016] An axial hole casting cavity 10 is provided on the outer spherical surface of the spherical surface 15. The axial hole casting cavity 10 is located in the radial direction of the spherical inner core 3 and perpendicular to the center line of the through hole of the spherical inner core 3. The axial hole casting cavity 10 and the spherical surface 15 are integrally die-casted. The inner cavity wall of the spherical casting cavity 5 is provided with an axial hole casting rod 9. The lower end of the axial hole casting rod 9 is sleeved in the axial hole casting cavity 10. There is a gap between the outer peripheral surface of the axial hole casting rod 9 and the inner cavity wall of the axial hole casting cavity 10. Under the action of centrifugal force, molten steel enters the gap between the axial hole casting rod 9 and the axial hole casting cavity 10 to form a valve stem shaft hole, thereby avoiding the process of machining the valve stem shaft hole of the spherical blank. A radial positioning groove 13 is provided on the left end face of the second half mold 2 to be embedded with the upper end of the axial hole casting rod 9. The axial hole casting rod 9 is embedded in the radial positioning groove 13 and then pressed on the right end face of the first half mold 1 to improve the fixing effect of the axial hole casting rod 9.

[0017] The first half mold 1 and the second half mold 2 can also be fixedly installed in the outer mold by the upper half mold and the lower half mold or the front half mold and the rear half mold through a locking device, and fixedly connected to the centrifuge turntable 12 through the outer mold. The advantage of using the outer mold to be fixedly connected to the centrifuge turntable 12 is that the outer mold can be universal when casting spheres of different diameters.

[0018] In the present invention, the molten steel is melted by precious metal materials such as cast steel, stainless steel, nickel alloy, austenitic alloy, etc.

[0019] Directional words such as "left", "right", "up", "down", "front" and "back" in the present invention are only for the directions in the drawings and are for the convenience of description and should not be understood as limiting the technical solution of the present invention.

Claims

1. A centrifugal casting mold for a large-caliber ball valve, comprising a first half mold (1) and a second half mold (2), wherein the inner cavities of the first half mold (1) and the second half mold (2) are spliced ​​to form a ball casting cavity (5), the ball casting cavity (5) is connected to a casting hole (6) at the center of the right end surface of the second half mold (2), the ball casting cavity (5) has a spherical inner cavity that is the same as the outer spherical surface of the ball blank, a spherical inner core (3) is arranged in the ball casting cavity (5), and the outer spherical surface of the spherical inner core (3) is At least two radial positioning rods (16) are provided on the spherical surface, and the radial positioning rods (16) are fixedly installed in radial positioning holes (18) on the inner wall of the spherical inner cavity formed between the first half mold (1) and the second half mold (2). The spherical inner core (3) has a central through hole (11), and an annular casting cavity (8) is formed between the outer spherical surface of the spherical inner core (3) and the inner cavity wall of the spherical casting cavity (5), and the annular casting cavity (8) is connected to the casting hole (6); the invention is characterized in that: The spherical inner core (3) adopts a hollow spherical structure, which is composed of an outer cylindrical surface of a straight cylinder (14) connected to a spherical surface (15), a hollow cavity (7) is provided between the outer cylindrical surface of the straight cylinder (14) and the inner wall of the spherical surface (15), and a radial positioning rod (16) is fixedly connected to the outer spherical surface of the spherical surface (15); a radial exhaust pipe (4) is provided on the inner hole wall of the straight cylinder (14), and the radial exhaust pipe (4) has a central exhaust hole (19), one end of which is connected to the hollow cavity (7) of the spherical inner core (3), and the other end of which radially extends to the center line of the straight cylinder (14).

2. The centrifugal casting mold for a large-diameter ball valve according to claim 1 is characterized in that: A plurality of radial through holes (17) are provided on the spherical inner core (3) and connect the central through hole (11) and the annular casting cavity (8). The radial through holes (17) are formed by welding a hollow circular tube (20) between a straight cylinder (14) and a spherical surface (15), thereby sealing and isolating the hollow cavity (7) of the spherical inner core (3) and the radial through holes (17).

3. The centrifugal casting mold for a large-diameter ball valve according to claim 1 or 2, characterized in that: An axial hole casting cavity (10) is provided on the outer spherical surface of the spherical surface (15), and the axial hole casting cavity (10) is located in the radial direction of the spherical inner core (3) and perpendicular to the center line of the through hole of the spherical inner core (3). The axial hole casting cavity (10) and the spherical surface (15) are integrally die-casted. The inner cavity wall of the spherical casting cavity (5) is provided with an axial hole casting rod (9), and the lower end of the axial hole casting rod (9) is sleeved in the axial hole casting cavity (10), and a gap is formed between the outer peripheral surface of the axial hole casting rod and the inner cavity wall of the axial hole casting cavity (10).

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