A method of forging a valve body blank, a method of manufacturing a valve body preform, and a valve body

Abstract

The application discloses a forging method of a valve body blank, a manufacturing method of a valve body preform and a valve body, and comprises the following steps: blank forming, primary forging, secondary forging and blank forming; wherein the blank forming is to provide a metal material, and the metal material is forged to form a blank; the primary forging is to put the blank into a die, upset and smooth to a first forging body with a height of a first height; the secondary forging is to press the first forging body away from the die into a press head to punch out a recess, and smooth to a second forging body with a second height; and the blank forming is to take out the press head, cool the second forging body to a first temperature, and form the valve body blank after furnace cooling to a second temperature. The valve body blank generated by the application consumes less pre-blank for turning two pieces of ball valve bodies; when turning the inner hole through the recess, the area to be turned is less than that of the prior art; the forging cost of the product is greatly reduced, and the risk coefficient of unqualified flaw detection of the ball valve inner hole position is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of valve body manufacturing, in particular to a valve body blank forging method, a valve body preform manufacturing method and a valve body. BACKGROUND

[0002] The two-piece ball valve is a relatively new type of ball valve, which has some unique advantages due to its structure, such as no friction when opening and closing, less wear of the seal, and small torque for opening and closing. This can reduce the size of the actuator. When combined with a multi-rotation electric actuator, it can achieve adjustment and strict shut-off of the medium. It is widely used in petroleum, chemical industry, urban water supply and drainage, and other strict shut-off working conditions.

[0003] However, the material of the two-piece ball valve body is ordinary carbon steel, and the conventional forging method directly forges it into a cylindrical forging, which will result in high forging cost of the product and high risk coefficient of unqualified flaw detection of the ball valve inner hole. SUMMARY

[0004] Therefore, the technical problem to be solved by the present application is that the material of the two-piece ball valve body is ordinary carbon steel, and the conventional forging method directly forges it into a cylindrical forging, which will result in high forging cost of the product and high risk coefficient of unqualified flaw detection of the ball valve inner hole.

[0005] To this end, the present application provides a valve body blank forging method, comprising: blank forming: providing a metal material, the metal material is forged into a blank;

[0006] First forging: the blank is put into a die and upset to a first forging body with a first height, the first forging body includes a first forging part with a first diameter and a second forging part with a second diameter; the first diameter is greater than the second diameter, and the first height is the straight line distance from the end of the first forging body away from the die to the bottom end of the die;

[0007] Second forging: the end of the first forging body away from the die is pressed into a press head to punch out a recess, and is flattened to a second forging body with a second height, the second forging body includes a third forging part with a third diameter and a fourth forging part with a second diameter, the second diameter is less than the third diameter, and the second height is the straight line distance from the end of the second forging body away from the die to the bottom end of the die; the second height is less than the first height;

[0008] Blank forming: the press head is removed, the second forging body is cooled to a first temperature, and after furnace cooling to a second temperature, a valve body blank is formed.

[0009] Optionally, the blank forming step includes:

[0010] Heating and holding: heating the metal material to a third temperature and holding at the third temperature for a first time;

[0011] Upsetting and rounding: upsetting the metal material after heating and holding, and rounding the metal material after the first upsetting;

[0012] Stretching and rounding: stretching the metal material after the upsetting and rounding, and rounding the metal material after the flattening to form a blank.

[0013] Optionally, the difference between the first height and the second height is 40-80 mm.

[0014] Optionally, the upsetting in the first forging step further comprises:

[0015] Second upsetting: second upsetting the blank;

[0016] Demolding and rounding: demolding and rounding the outer circle of the blank after the second upsetting;

[0017] Third upsetting: third upsetting the blank after the demolding and rounding in the die.

[0018] Optionally, the second forging step further comprises:

[0019] Demolding the second forged body, rounding the outer circle of the third forged part, and flattening the end face.

[0020] Optionally, the first temperature ranges from 350-650℃, and the second temperature is less than or equal to 250℃.

[0021] Optionally, the upsetting ratio of the first upsetting ranges from greater than or equal to 1.8, and the stretching ratio of the stretching ranges from greater than or equal to 1.8.

[0022] Optionally, the metal material forms a collapsed corner during the upsetting and rounding and the stretching and rounding.

[0023] The stretching and rounding step further comprises: second rounding to ensure that the angle of the collapsed corner is less than or equal to 50°.

[0024] Optionally, the total forging ratio during the blank forming, the first forging, the second forging, and the rough blank forming is greater than or equal to 5.

[0025] A manufacturing method of a valve body preform, characterized in that it comprises the forging method of the valve body rough blank; and the valve body rough blank is once turned to form a valve body preform.

[0026] A valve body, characterized in that it is a valve body preform manufactured by the manufacturing method of the valve body preform according to claim 10.

[0027] The valve body comprises a valve body and a through hole, the through hole is provided in the valve body;

[0028] The inner wall surface and the outer wall surface of the valve body preform are processed by secondary turning to form the valve body and the through hole.

[0029] The technical scheme provided by the present application has the following advantages:

[0030] 1. The embodiment provides a forging method of a valve body blank, comprising: blank forming, primary forging, secondary forging and blank forming; wherein the blank forming provides a metal material, and the metal material is forged to form a blank; the primary forging is to put the blank into a die, upset and flatten to a first forging body with a first height, the first forging body comprising a first forging part with a first diameter and a second forging part with a second diameter; the first diameter is greater than the second diameter, and the first height is the straight line distance from the end of the first forging body away from the die to the bottom end of the die; the secondary forging is to press the end of the first forging body away from the die into a press head to punch out a recess part, and flatten to a second forging body with a second height, demould the second forging body, roll the outer circle of the third forging part and flatten the end face; the second forging body comprises a third forging part with a third diameter and a fourth forging part with the second diameter, the second diameter is smaller than the third diameter, and the second height is the straight line distance from the end of the second forging body away from the die to the bottom end of the die; the second height is smaller than the first height; the blank forming is to take out the press head, cool the second forging body to a first temperature, and form the valve body blank after furnace cooling to a second temperature; the temperature range of the first temperature is 350-650 DEG C; the temperature range of the second temperature is less than or equal to 250 DEG C; and the difference between the first height and the second height is 40-80 mm.

[0031] The step specifically comprises: S1, blank forming: providing a metal material, and forging the metal material to form a blank; S2, first forging: placing the blank in the step S1 into a die, upsetting and flattening to a first forging body with a first height, the first forging body comprising a first forging part with a first diameter and a second forging part with a second diameter; S3, second forging: performing second forging on the blank after the first forging in the step S2, pressing the first forging body away from the end of the die into a press head to punch out a recess part, and flattening to a second forging body with a second height, the second forging body comprising a third forging part with a third diameter and a fourth forging part with the second diameter, the second diameter being smaller than the third diameter, and the second height being a straight line distance from the end of the second forging body away from the die to the bottom end of the die; the second height is smaller than the first height; demolding the second forging body, rolling the outer circle of the third forging part and flattening the end face; S4, forming a rough blank: removing the press head, cooling the second forging body to a first temperature, and forming a valve body rough blank after furnace cooling to a second temperature; after air cooling the blank to 350-650 DEG C, furnace cooling is performed again, and the temperature of the furnace cooling is 250 DEG C; the production of internal pearlite organization can be ensured, and a large amount of bainite and large blocky ferrite, mixed crystals and other impurities can be eliminated. Through the above steps, the metal material can be forged into a shape similar to the two-piece ball valve body; the valve body rough blank and the two-piece ball valve body to be cut and formed are similar in shape; and generally, without the aid of the die in the process, the material at the third forging part and the fourth forging part step and the recess part inner hole cannot be saved, compared with directly using a cylindrical rough blank, the valve body rough blank produced by the method in the embodiment consumes less pre-material for machining the two-piece ball valve body; when the recess part is used to machine the inner hole, the area to be machined is less than that in the prior art; the forging cost of the product can be greatly reduced, and the risk coefficient of unqualified detection of the inner hole part of the ball valve can be reduced.

[0032] 2. In this embodiment, the blank forming step includes: heating and holding, upsetting and rounding, and elongating and rounding; wherein the heating and holding is heating the metal material to a third temperature and holding at the third temperature for a first time; the upsetting and rounding is upsetting the metal material after heating and holding, and rounding the metal material after the first upsetting; the elongating and rounding is elongating the metal material after the upsetting and rounding, and flattening and then rounding the metal material after the elongating to form the blank. The upsetting ratio of the first upsetting is greater than or equal to 1.8; the elongating ratio of the elongating is greater than or equal to 1.8. In the process of the upsetting and rounding and the elongating and rounding, the metal material will form a collapsed corner; the step of the elongating and rounding further includes: the second rounding to ensure that the angle of the collapsed corner is less than or equal to 50°. The temperature range of the third temperature is 1200-1260℃. This step is specifically as follows: S11, placing the continuous casting round on the sawing bed to obtain the metal material; S12, placing the metal material in the forging heating furnace to heat and heat at 1200-1260℃ for a certain time, and the holding time must be lengthened according to the increase of the diameter of the metal material; S13, taking out the metal material after the heating and holding, placing it on the anvil of the forging press, and standing and upsetting it for the first time to ensure that the upsetting ratio is greater than or equal to 1.8, so as to eliminate the original as-cast porosity and other defects, refine the grains, and ensure the uniformity of the composition and organization; then, the first rounding operation is performed to ensure that the metal material is closer to a regular cylindrical body; S14, elongating the metal material obtained in the step S13 to a certain size to ensure that the elongating ratio is greater than or equal to 1.8, if the elongating ratio is less than the value, the original as-cast porosity and other defects in the forged piece cannot be completely eliminated, the grains are not refined enough, and the end face is flattened, the elongated quadrilateral or hexagonal is rounded to form a metal material, and the collapsed corner between the outer circle and the end face of the metal material is less than or equal to 50, so that the filling rate of the forged piece in the corner of the mold is higher during the subsequent mold forming, that is, the allowance of the stepped bending part of the two-piece ball valve body is ensured.

[0033] 3. The present application provides a manufacturing method of a valve body preform, which performs first turning on a valve body blank to obtain a valve body preform, and the shape of the valve body preform is closer to a two-piece ball valve body than the valve body blank, which is more conducive to the forming of the valve body. As shown in the figure, the dashed line represents the valve body preform, the solid line represents the valve body blank, and the part between the dashed line and the solid line is the cutting waste. The area to be turned is less than that of the prior art; the forging cost of the product and the risk coefficient of unqualified detection of the inner hole part of the ball valve are greatly increased. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or the prior art description. Obviously, the drawings described below are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0035] Figure 1 Method flowchart for the forging method of the valve body blank provided in this embodiment;

[0036] Figure 2 Structure diagram of the blank provided in this embodiment;

[0037] Figure 3 Structure diagram of the first forged body provided in this embodiment;

[0038] Figure 4 Structure diagram of the second forged body provided in this embodiment;

[0039] Figure 5 Structure diagram of the valve body blank provided in this embodiment;

[0040] Figure 6 Structure diagram of the two-piece ball valve body provided in this embodiment;

[0041] BRIEF DESCRIPTION OF THE DRAWINGS

[0042] 1 - blank;

[0043] 2 - first forged body; 21 - first forged part; 22 - second forged part;

[0044] 3 - second forged body; 31 - third forged part; 32 - fourth forged part; 33 - recess;

[0045] 4 - valve body blank;

[0046] 5 - valve body preform;

[0047] 6 - valve body; 61 - valve body body; 62 - through hole. DETAILED DESCRIPTION

[0048] The technical solutions of the present application will be described clearly and completely below in conjunction with the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0049] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0050] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0051] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0052] Example 1

[0053] This embodiment provides a forging method for valve body blanks, such as... Figures 1 to 6 As shown, it includes: billet 1 forming, primary forging, secondary forging, and blank forming; wherein, billet 1 forming involves providing a metal material, and forging the metal material to form billet 1; primary forging involves placing billet 1 into a mold and upsetting and leveling it to a first forging body 2 with a height of a first height, the first forging body 2 including a first forging part 21 with a diameter of a first diameter and a second forging part 22 with a diameter of a second diameter; the first diameter is greater than the second diameter, and the first height is the straight-line distance from the end of the first forging body 2 away from the mold to the bottom of the mold; secondary forging involves forging the end of the first forging body 2 away from the mold... The pressure head punches out the recessed portion 33 and flattens it to a second height to form the second forged body 3. The second forged body 3 is demolded, and the outer circle of the third forging portion 31 is rolled and the end face is flattened. The second forged body 3 includes a third forging portion 31 with a diameter of a third diameter and a fourth forging portion 32 with a diameter of a second diameter. The second diameter is smaller than the third diameter. The second height is the straight-line distance from the end of the second forged body 3 away from the mold to the bottom of the mold. The second height is smaller than the first height. The blank forming process involves removing the pressure head, cooling the second forged body 3 to a first temperature, and then furnace cooling it to a second temperature to form the valve body blank 4. The temperature range of the first temperature is 350-650℃; the temperature range of the second temperature is less than or equal to 250℃; and the difference between the first height and the second height is 40-80mm.

[0054] The step specifically comprises: S1, blank 1 forming: providing a metal material, and forging the metal material to form the blank 1; S2, primary forging: placing the blank 1 in the step S1 into a die, upsetting and flattening to a first forging body 2 with a first height, the first forging body 2 comprising a first forging part 21 with a first diameter and a second forging part 22 with a second diameter; S3, secondary forging of the blank 1 after the primary forging in the step S2, pressing the first forging body 2 away from the end of the die into a press head to punch out a recess part 33, and flattening to a second forging body 3 with a second height, the second forging body 3 comprising a third forging part 31 with a third diameter and a fourth forging part 32 with the second diameter, the second diameter being smaller than the third diameter, and the second height being a straight line distance from the end of the second forging body 3 away from the die to the bottom end of the die; the second height is smaller than the first height; demolding the second forging body 3, rolling the outer circle of the third forging part 31 and flattening the end face; S4, blank forming: removing the press head, cooling the second forging body 3 to a first temperature, and forming a valve body blank 4 after furnace cooling to a second temperature; air cooling the blank 1 to a surface temperature of 350-650 DEG C, and then furnace cooling, the temperature of the furnace cooling being 250 DEG C; which can ensure the generation of internal pearlite structure and eliminate a large amount of bainite and massive ferrite, mixed crystals and other impurities. Through the above steps, the metal material can be forged into a shape similar to the two-piece ball valve body; the valve body blank 4 is similar to the shape of the two-piece ball valve body to be cut and formed; and in general, without the aid of the die in the process, the material at the third forging part 31 and the fourth forging part 32 steps and the recess part 33 inner hole cannot be saved, compared with directly using a cylindrical blank, the valve body blank 4 generated by using the method in the embodiment consumes less pre-material for machining the two-piece ball valve body; when the recess part 33 is used for turning the inner hole, the area to be turned is less than that in the prior art; which can greatly reduce the forging cost of the product and reduce the risk coefficient of unqualified detection of the inner hole part of the ball valve.

[0055] In the embodiment, the blank 1 forming step comprises: heating and holding, upsetting and rolling, and elongating and rolling; the heating and holding is heating the metal material to a third temperature and holding at the third temperature for a first time; the upsetting and rolling is upsetting the metal material after the heating and holding, rolling the metal material after the first upsetting, and elongating the metal material after the upsetting and rolling; the elongating and rolling is elongating the metal material after the upsetting and rolling, flattening, and second rolling to form the blank 1. The upsetting ratio of the first upsetting is greater than or equal to 1.8; the elongating ratio of the elongating is greater than or equal to 1.8. In the process of the upsetting and rolling and the elongating and rolling, the metal material forms a collapsed corner; the step of the elongating and rolling further comprises: the second rolling to ensure that the angle of the collapsed corner is less than or equal to 50°. The third temperature is in the range of 1200-1260℃. The step is specifically as follows: S11, placing the continuous casting round on the sawing bed to obtain the metal material; S12, placing the metal material in the forging heating furnace to heat and rise, and holding at 1200-1260℃ for a certain time, the holding time must be lengthened according to the increase of the diameter of the metal material; S13, taking out the metal material after the heating and holding, placing it on the anvil of the forging press, and standing and upsetting for the first time to ensure that the upsetting ratio is greater than or equal to 1.8, so as to eliminate the original casting porosity and other defects, refine the grains, and ensure the homogenization of the composition and organization; then, the first rolling is performed to ensure that the metal material is closer to a regular cylindrical body; S14, elongating the metal material obtained in the step S13 to a certain size to ensure that the elongating ratio is greater than or equal to 1.8; if the elongating ratio is less than the value, the original casting porosity and other defects in the internal part of the forging cannot be completely eliminated, the grains are not refined enough, and the end face is flattened; the elongated four or six sides are rolled to ensure that the collapsed corner between the outer circle and the end face of the metal material is less than or equal to 50, so as to ensure that the filling rate of the forging in the corner of the mold is higher in the subsequent mold forming, that is, the allowance of the step bending part of the two pieces of ball valve body is ensured.

[0056] In the embodiment, as shown in Figure 3 The upsetting in the first forging step further comprises: second upsetting, demolding and rolling, and third upsetting; the blank 1 is subjected to the second upsetting; the blank 1 after the second upsetting is subjected to the demolding and rolling; the blank 1 after the demolding and rolling is placed in the mold to be subjected to the third upsetting. The purpose of the second upsetting is to make the metal material fully forge through on the basis of ensuring the size and stress state of the blank 1 required by the third upsetting, and to complete the basic task of main body deformation. The purpose of the third upsetting is to ensure that the blank 1 reaches the size required by the formed part; the blank 1 always maintains the best stress and strain state, so as to avoid that the defects of the first upsetting are pulled apart or new forging defects are generated.

[0057] In the present embodiment, the total forging ratio in the processes of blank 1 forming, primary forging, secondary forging and rough blank forming ranges from greater than or equal to 5. The guarantee of the total forging ratio can reduce the defect equivalent of recess 33 to φ2, if the total forging ratio is not guaranteed, the defect equivalent of recess 33 will be φ3, or even φ5 or above, so the guarantee of the total forging ratio can guarantee the qualification of the core nondestructive testing of the forged piece.

[0058] The forging method of the valve body rough blank 4 provided in the present embodiment is specifically as follows:

[0059] Blank 1 is formed to provide a metal material, the metal material is heated to a third temperature and is kept at the third temperature for a first time; upsetting and rounding is performed on the metal material after heating and keeping to perform primary upsetting, and the metal material after primary upsetting is rounded to perform elongation and is flattened to perform secondary rounding to form blank 1.

[0060] Blank 1 is placed in a die to be upset and flattened to a first forging body 2 with a height of a first height; the end of the first forging body 2 away from the die is pressed into a press head to punch out recess 33 and is flattened to a second height to form a second forging body 3, the second forging body 3 is demolded, the outer circle of third forging part 31 is rolled and the end face is flattened; rough blank forming is performed to take out the press head, the second forging body 3 is cooled to a first temperature, and the valve body rough blank 4 is formed after furnace cooling to a second temperature.

[0061] Embodiment 2

[0062] A manufacturing method of a valve body preform, comprising: the forging method of the valve body rough blank described in embodiment 1; performing primary turning on the valve body rough blank 4 to form a valve body preform 5. The valve body preform 5 obtained by performing primary turning on the valve body rough blank 4 is closer to the two-piece ball valve body 6 than the valve body rough blank 4, and is more conducive to the forming of the valve body 6, as shown in Figure 5 The dashed line represents the valve body preform 5, the solid line represents the valve body rough blank 4, and the part between the dashed line and the solid line is cutting waste, and the area to be turned is less than the prior art; the forging cost of the product can be greatly reduced, and the risk coefficient of the nondestructive testing unqualified of the inner hole part of the ball valve can be reduced.

[0063] Embodiment 3

[0064] A valve body, a valve body preform 5 made by the method of manufacturing a valve body preform described in Example 2; the valve body 6 includes a valve body 61 and a through hole 62, the through hole 62 is provided in the valve body 61; the inner wall surface and the outer wall surface of the valve body preform 5 are turned by secondary turning to form the valve body 61 and the through hole 62. By using the valve body preform 5, the outer surface of the valve body preform 5 is turned and bored, the boring is adjusted until the through hole 62 and the valve body 61 in the required two-piece ball valve body 6 are formed, and the waste produced by using this method is less.

[0065] Obviously, the above examples are only examples for clearly illustrating, but not limit the embodiments. For those skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Here, all the embodiments need not and cannot be exhausted. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A forging method for a valve body blank, characterized in that, include: Billet (1) forming: A metal material is provided, which is forged into a billet (1). One-time forging: The billet (1) is placed in the mold and upset and leveled to a first forging body (2) with a height of a first height. The first forging body (2) includes a first forging part (21) with a diameter of a first diameter and a second forging part (22) with a diameter of a second diameter. The first diameter is greater than the second diameter, and the first height is the straight-line distance from the end of the first forging body (2) away from the mold to the bottom of the mold. Secondary forging: The end of the first forging body (2) away from the mold is pressed into the recessed part (33) by the press head and flattened to a second height to form a second forging body (3). The second forging body (3) includes a third forging part (31) with a diameter of a third diameter and a fourth forging part (32) with a diameter of a second diameter. The second diameter is smaller than the third diameter. The second height is the straight-line distance from the end of the second forging body (3) away from the mold to the bottom of the mold. The second height is smaller than the first height. Blank forming: Remove the pressure head, cool the second forging body (3) to the first temperature, and furnace cool it to the second temperature to form the valve body blank (4). The forming steps of the blank (1) include: Heating and heat preservation: The metal material is heated to a third temperature and kept at the third temperature for a first time; Upsetting and rounding: The heated and heat-preserved metal material is upset once, and the upset metal material is rounded once; Lengthening and rounding: The metal material after upsetting and rounding is lengthened, flattened, and then rounded a second time to form a billet (1).

2. The forging method for the valve body blank according to claim 1, characterized in that, include: The difference between the first height and the second height is 40-80mm.

3. The forging method for the valve body blank according to claim 1, characterized in that, include: The upsetting process in the primary forging step also includes: Secondary upsetting: The billet (1) is subjected to secondary upsetting; Demolding and rolling: Demold and roll the outer circle of the blank (1) after the second upsetting; Three-stage upsetting: The blank (1) after demolding and rolling is placed into the mold for three-stage upsetting.

4. The forging method for the valve body blank according to claim 1, characterized in that, The secondary forging process also includes: Demold the second forging body (3), roll the outer circle of the third forging part (31) and flatten the end face.

5. The forging method for the valve body blank according to claim 1, characterized in that, The first temperature range is 350-650℃; the second temperature range is less than or equal to 250℃; and the third temperature range is 1200-1260℃.

6. The forging method for the valve body blank according to claim 1, characterized in that, The upsetting ratio for the first upsetting is greater than or equal to 1.8; the elongation ratio for the drawing is greater than or equal to 1.

8.

7. The forging method for the valve body blank according to claim 1, characterized in that, During the upsetting and drawing processes, the metal material will form collapsed corners; The lengthening and rounding step further includes: secondary rounding to ensure that the angle of the collapsed angle is less than or equal to 50°.

8. The forging method for the valve body blank according to any one of claims 1-7, characterized in that, The range of the total forging ratio in the billet (1) forming, primary forging, secondary forging and blank forming process is greater than or equal to 5.

9. A method for manufacturing a valve body preform, characterized in that, include: The forging method of the valve body blank according to any one of claims 1-8: the valve body blank (4) is turned once to form the valve body preform (5).

10. A valve body, characterized in that, A valve body preform (5) manufactured using the manufacturing method of the valve body preform according to claim 9; The valve body (6) includes: a valve body body (61) and a through hole (62), the through hole (62) being disposed within the valve body body (61); The valve body body (61) and through hole (62) are formed by secondary machining of the inner and outer wall surfaces of the valve body preform (5).

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