Casting method of ball valve with shaft

Abstract

A casting method of a ball valve with a shaft belongs to the technical field of casting, is used for solving the problem of shrinkage porosity of a hot spot part of the ball valve with the shaft, and comprises the following steps: S01, arranging a first riser at a position, corresponding to an inner cavity of a ball valve main body, on a mold core bag after reverse differencing of a modeled ball valve model with the shaft, the first riser is used for feeding a hot spot part at the joint of the shaft and the ball valve main body; and S02, a first riser neck is arranged at the hot spot part, and the thickness of the first riser neck is larger than the maximum diameter of the hot spot part, so that smoothness of a feeding channel between the first riser neck and the hot spot part is guaranteed. The first riser directly arranged at the hot spot part is arranged in the inner diameter cavity of the ball valve, so that a better feeding effect on the hot spot part is realized, the problem of shrinkage porosity of the hot spot part is solved, meanwhile, the problem that the residual part of the riser needs to be cleaned when the first riser is arranged at the hot spot part is avoided, and the production efficiency is improved. And the surface quality and the production efficiency of the ball valve with the shaft are improved.

Description

Technical Field

[0001] The present invention relates to the field of casting technology, and particularly relates to a casting method. Background Art

[0002] As a supporting part in the hydropower industry, the castings of the hydropower belt shaft ball valve have the following structure. It mainly consists of two parts, which are composed of the ball valve body and the shaft. The lengths on both sides of the shaft reach 5000 mm, and the diameter is nearly 1000 mm. It belongs to the ultra-long and thick large hydropower valve body castings. Among them, the shaft is the part that bears the force of the hydropower assembly unit, and its quality requirements are strict, and casting defects such as center shrinkage porosity and cracks are not allowed. Analyzing from the cross-sectional view of the casting, a very large hot spot circle (the inscribed circle diameter at the hottest spot of the maximum wall thickness of the casting) is formed at the intersection of the shaft and the ball valve body, and its diameter reaches nearly 1000 mm. The intersection hot spot at this part is very large, indicating that this part is the key to solving the solidification feeding problem in the casting process.

[0003] To solve the above problems, the traditional process is to design a first riser at the intersection of the shaft and the ball valve body to achieve the feeding of the hot spot circle by the first riser, then design a second riser at the upper end of the ball valve body, and design sectional chill blocks required for the casting process in the middle part between the first riser and the second riser.

[0004] There are the following problems in casting the ball valve with a shaft by using the above process:

[0005] 1) Designing a first riser at the intersection of the shaft and the ball valve body increases the hot spot at the intersection of the shaft and the ball valve body. During solidification, the first riser cannot feed the center part of the hot spot circle, and there are excessive shrinkage porosities detected by NDT.

[0006] 2) Designing a first riser at the intersection of the shaft and the ball valve body makes the intersection part of the three belong to a thick and large structure, and its casting solidification structure is not dense, and cracks are easily generated under the thermal effects such as riser cutting and air gouging.

[0007] 3) The intersection part of the shaft and the ball valve body belongs to a curved surface transition part. Designing a first riser at this part has a large coverage area, and it is impossible to ensure the curved surface shape of the casting during riser cutting and air gouging repair. Problems such as cutting shortage and excess have occurred, resulting in multiple repetitions of the process and waste of production costs.

[0008] 4) The shaft is an important force-bearing assembly surface, and its structure is thick and large, and center shrinkage porosity is easily generated during solidification shrinkage. Summary of the Invention

[0009] In view of the shrinkage porosity defects in the hot spot parts and the problem that the residual parts of the risers at the curved surface parts are difficult to clean caused by setting risers between the shaft and the ball valve when producing the ball valve with a shaft, it is necessary to propose a casting method for the ball valve with a shaft.

[0010] A casting method for a ball valve with a shaft includes,

[0011] S01. On the core package after reverse subtraction of the modeled shafted ball valve model, at the position corresponding to the inner cavity of the ball valve body, a first riser is provided. The first riser is used to compensate for the hot spot at the connection between the shaft and the ball valve body.

[0012] S02. At the hot spot, a first riser neck is provided. The thickness of the first riser neck is greater than the maximum diameter of the hot spot to ensure the smoothness of the feeding channel between the first riser neck and the hot spot.

[0013] Preferably, the distance from the center of the shaft to the upper part of the first riser neck should be greater than half of the diameter of the shaft of the shafted ball valve to ensure that the feeding of the first riser to the hot spot can form a gravity head and achieve a good feeding effect.

[0014] Preferably, a heat insulation board is also arranged around the outer wall of the first riser. The heat insulation board can play a role in heat insulation for the first riser, thereby improving the feeding capacity and efficiency of the first riser to the hot spot.

[0015] As an optimization of this technical solution, a second riser is also provided on the connecting flange end face of the shafted ball valve. The second riser is used to compensate for the connecting flange of the shafted ball valve.

[0016] Preferably, the second riser is a stepped riser, including a second main riser and a second supplementary riser. The second supplementary riser is arranged below the second main riser, and the second supplementary riser is arranged on the end side face of the connecting flange to smoothly feed the connecting flange vertically downward and achieve good feeding of the entire flange.

[0017] As an optimization of this technical solution, the first riser and the second riser are separately arranged, and a sectional chill is also arranged between the first riser and the second riser. The sectional chills are arranged in a long strip shape in the direction perpendicular to the axis, that is, at least one row of the sectional chills is arranged directly between the first riser and the second riser to realize the isolation of the feeding of the hot spot and the feeding of the flange and avoid the negative effects caused by their mutual influence.

[0018] As an optimization of this technical solution, in order to further improve the feeding capacity of the first riser to the hot spot, a chilling mechanism is arranged around the shaft. The chilling mechanism can strongly chill the shaft, that is, it realizes the rapid solidification of the metal liquid on the surface layer of the shaft and reduces the modulus of the shaft, thereby effectively avoiding the linear shrinkage porosity problem in the core part of the shaft.

[0019] Preferably, the chilling mechanism includes a first chilling mechanism and a second chilling mechanism. The first chilling mechanism is arranged on the shaft section close to the ball valve; the second chilling mechanism is arranged on the shaft end to realize the chilling of the entire shaft.

[0020] Advantages of the technical solution of the present invention: By changing the first riser directly arranged at the hot spot to be arranged in the inner diameter cavity of the ball valve, a better feeding effect on the hot spot is achieved, the problem of shrinkage porosity at the hot spot is solved, and at the same time, the problem of cleaning the residual part of the riser on the hot spot is avoided, improving the surface quality and production efficiency of the ball valve with a shaft. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic structural diagram of a hydroelectric ball valve with a shaft;

[0022] Figure 2 is a schematic diagram of the hot spot part of the hydroelectric ball valve with a shaft;

[0023] Figure 3 is a three-dimensional schematic diagram of the riser layout of the present invention;

[0024] Figure 4 is a sectional schematic diagram of the layout of the first riser of the present invention;

[0025] Figure 5 is a sectional schematic diagram of the layout of the second riser of the present invention;

[0026] Wherein, 1 - connecting flange; 2 - shaft; 3 - ball valve body; 4 - hot spot part; 7 - first chill mechanism; 8 - second chill mechanism; 9 - first riser neck; 10 - first riser; 11 - second main riser; 12 - insulation board; 13 - second supplementary riser; 14 - sectional chill. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] In order to more clearly illustrate the technical solution of the present invention, the technical solution of the invention content will be described in detail in combination with the drawings. Obviously, the following description is some typical embodiments of the present invention. For those of ordinary skill in the art, other solutions can be obtained based on these embodiments without creative work.

[0028] Now taking a hydroelectric ball valve with a shaft as shown in Figure 1 and Figure 2 as an example, the specific implementation of the technical solution of the present invention will be described. In Figure 1 and Figure 2 , the hydroelectric ball valve with a shaft includes a ball valve body 3, a connecting flange 1, a shaft 2 and a hot spot part 4.

[0029] An implementation method includes,

[0030] S11, arranging a first riser 10 at a position corresponding to the inner cavity of the ball valve body 3 on the core package after reverse subtraction of the modeled ball valve model with a shaft 2, and the first riser 10 is used to feed the hot spot part 4 at the connection of the shaft 2 and the ball valve body 3;

[0031] S12. A first riser neck 9 is provided at the hot spot portion 4. The thickness of the first riser neck 9 is greater than the maximum diameter of the hot spot portion 4 to ensure the smoothness of the feeding channel between the first riser neck 9 and the hot spot portion 4.

[0032] As a supplement to this embodiment, the cross-sectional shape of the first riser neck 9 can be square, and the side length of the first riser neck 9 is 1.1 times the maximum diameter of the hot spot portion 4, so as to achieve full coverage of the hot spot portion 4.

[0033] As a supplement to this embodiment, the modulus M2 of the first riser neck 9 is 1.2 times the modulus M1 of the hot spot portion 4.

[0034] As a supplement to this embodiment, the distance from the center of the shaft 2 to the first riser neck 9 should be greater than half of the diameter of the shaft 2 of the shafted ball valve to ensure that the feeding of the first riser 10 to the hot spot portion 4 can form a gravity head and achieve a good feeding effect.

[0035] As a supplement to this embodiment, the modulus M3 of the first riser 10 is 1.2 times the modulus M2 of the first riser neck 9, and there are two first risers 10. The distance between each first riser 10 and the inner cavity wall of the ball valve body 3 is at least 100 mm to ensure that there will be no problem of sand sintering and adhering sand between the riser and the inner diameter of the ball valve during the casting of the shafted ball valve.

[0036] As a supplement to this embodiment, a heat preservation board 12 is also arranged around the outer wall of the first riser 10. The heat preservation board 12 can play a role in heat preservation of the first riser 10, thereby improving the feeding ability and efficiency of the first riser 10 to the hot spot portion 4.

[0037] In another embodiment, a second riser is also provided on the end face of the connecting flange 1 of the shafted ball valve. The second riser is used to feed the connecting flange 1 of the ball valve body 3.

[0038] As a supplement to this embodiment, the second riser is a stepped riser, including a second main riser 11 and a second supplementary riser 13. The second supplementary riser 13 is arranged below the second main riser 11, and the second supplementary riser 13 is arranged on the end face of the connecting flange 1 to smoothly feed the connecting flange 1 vertically downward and achieve good feeding of the entire flange.

[0039] In another embodiment, the first riser 10 and the second riser are separately arranged, and a sectional chill 14 is further provided between the first riser 10 and the second riser. The sectional chills 14 are arranged in a strip shape in the direction of the vertical axis 2, that is, at least one row of the sectional chills 14 is provided directly between the first riser 10 and the second riser, so as to isolate the feeding of the hot spot part 4 from the feeding of the flange and avoid the negative effects brought by their mutual influence.

[0040] In another embodiment, in order to further improve the feeding capacity of the first riser 10 for the hot spot part 4, a chill mechanism is arranged around the axis 2. The chill mechanism can strongly chill the axis 2, that is, it realizes the rapid solidification of the molten metal on the surface layer of the axis 2 and reduces the modulus of the axis 2, thereby effectively avoiding the problem of linear shrinkage porosity in the core of the axis 2.

[0041] As a supplement to this embodiment, the chill mechanism is a barrel sleeve with a thickness of 100 mm sleeved outside the axis 2, and the chill mechanism can include a first chill mechanism 7 and a second chill mechanism 8. The first chill mechanism 7 is arranged on the shaft section close to the ball valve; the second chill mechanism 8 is arranged at the shaft end, so as to realize the chilling of the entire axis 2. Specifically, the second chill mechanism 8 can be a cap structure and directly buckled on the shaft end of the axis 2; the first chill mechanism 7 is a hollow cylindrical tube and directly sleeved on the shaft section of the axis 2 close to the ball valve.

[0042] As a supplement to this embodiment, the first chill mechanism 7 includes a first half-barrel sleeve and a second half-barrel sleeve. The first half-barrel sleeve and the second half-barrel sleeve are assembled on the shaft section of the axis 2 close to the ball valve body 3, so that the first chill mechanism 7 is closely attached to the shaft section close to the ball valve body 3, that is, a fully enclosed first chill mechanism is formed around the shaft section of the axis 2 close to the ball valve body 3, and the chilling effect on the shaft section close to the ball valve body 3 is realized.

[0043] As a supplement to this embodiment, in order to further improve the chilling effect of the chill mechanism on the axis 2, the chill mechanism needs to be closely attached to the axis 2, that is, it is necessary to ensure the roughness of the inner surface of the chill mechanism and avoid obvious convex points or pits on the inner surface of the chill mechanism, so as to ensure the contact area between the chill mechanism and the axis 2, thereby improving the chilling effect.

[0044] The above embodiments are only descriptions of a typical application of the technical solution of the present invention. On the basis of being reasonable and not requiring creative labor, reasonable expansion can also be carried out.

Claims

1. A casting method for a shaft-mounted ball valve, characterized in that Including, S01, a first riser is provided at a position corresponding to the inner cavity of the ball valve body on the core package after reverse subtraction of the modeled shafted ball valve model. The first riser is used to compensate for the hot spot at the connection between the shaft and the ball valve body; S02, a first riser neck is provided at the hot spot. The thickness of the first riser neck is greater than the maximum diameter of the hot spot to ensure the smoothness of the feeding channel between the first riser neck and the hot spot.

2. The casting method of the shafted ball valve according to claim 1, characterized in that, The distance from the center of the shaft to the upper part of the first riser neck should be greater than half of the diameter of the shaft of the shafted ball valve.

3. The casting method of the shafted ball valve according to claim 1, characterized in that, A heat preservation board is also arranged around the outer wall of the first riser.

4. The casting method of the shafted ball valve according to any one of claims 1-3, characterized in that, A second riser is also provided on the connecting flange end face of the shafted ball valve. The second riser is used to compensate for the connecting flange of the shafted ball valve.

5. The casting method of the shafted ball valve according to claim 4, characterized in that, The second riser is a stepped riser, including a second main riser and a second supplementary riser. The second supplementary riser is arranged below the second main riser, and the second supplementary riser is arranged on the end side face of the connecting flange.

6. The casting method of the shafted ball valve according to any one of claims 1-3, characterized in that, The first riser and the second riser are arranged separately, and a sectional chill is also provided between the first riser and the second riser.

7. The casting method of the shafted ball valve according to claim 6, characterized in that, The sectional chills are arranged in a strip shape in the direction perpendicular to the axis.

8. The casting method of the shafted ball valve according to any one of claims 1-3, characterized in that, A chill mechanism is arranged around the shaft, and the chill mechanism can perform strong chilling on the shaft.

9. The casting method of the shafted ball valve according to claim 8, characterized in that, The chill mechanism includes a first chill mechanism and a second chill mechanism. The first chill mechanism 7 is arranged on the shaft section close to the ball valve; The second chill mechanism is arranged at the shaft end to achieve chilling of the entire shaft.

10. The casting method of the shafted ball valve according to claim 9, characterized in that, The first chill mechanism includes a first half barrel sleeve and a second half barrel sleeve, and the first half barrel sleeve and the second half barrel sleeve are assembled on the shaft section of the shaft close to the ball valve body.

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