TW201525332A - Assembly, precursor and process for forming hollow bodies - Google Patents

Abstract

Assembly (1, 1', 1") for forming a hollow metal body (2) comprising a precursor (4) having a substantially tubular wall (6), which extends about an axis (X) and delimits a body compartment (8), and a forming device (10, 10', 10"). Such device identifies one or more injection passageways (12, 12') of a pressurised liquid in the body compartment (8) to induce an expansion of the latter, and comprises a pair of half-moulds (14, 16), which jointly delimit a mould chamber (18) accommodating said precursor (4) and configured to contain plastic deformations of the tubular wall (6) following expansion. Such device comprises axial compression means (14, 16; 80, 80') of the precursor (4) to deform the tubular wall (6) radially externally and obtain the metal body (2).

Description

Components, precursors and programs for forming hollow bodies

The invention relates to components and procedures for forming hollow bodies and also to precursors used in the above described assemblies or programs.

The use of ball valves is known in many technical fields for the passage of fluids in a reversible manner.

Forging a high temperature machining or metal bar processing is a conventional method for manufacturing the ball in the above ball valve.

However, the known techniques described have the disadvantage of high energy consumption and various post-processing steps, particularly in order to obtain a debris removal mechanical operation by a ball mounted in the valve body.

Accordingly, the present invention is in the above scope, and it is sought to provide a significantly simpler apparatus and method as compared to the prior art system to enable the manufacture of the above-described reformable elements on a large scale.

The purpose is achieved by the component according to claim 1, by the procedure according to claim 15, and by the The body is reached. These independent claims then show their advantages or preferred embodiments.

1‧‧‧ components

1’‧‧‧ components

1"‧‧‧ components

2‧‧‧Hollow metal body

4‧‧‧ precursor

4’‧‧‧ precursor

4"‧‧‧ precursors

6‧‧‧Tubular wall

8‧‧‧ body compartment

10‧‧‧ forming device

10’‧‧‧ forming device

10"‧‧‧ forming device

12‧‧‧Injection channel

12’‧‧‧Injection channel

14‧‧‧Half mold

16‧‧‧Half mold

18‧‧‧Molding chamber

20‧‧‧Export

20’‧‧‧Export

22‧‧‧Parts

24‧‧‧Conical inlet surface

26‧‧‧planar cylindrical surface

28‧‧‧External surface

30‧‧‧Internal surface

30’‧‧‧Internal surface

32‧‧‧Linear actuators

34‧‧‧Linear actuator

36‧‧‧Axis movement mechanism

38‧‧‧ Pressurized source

40‧‧‧ Pressurized source

42‧‧‧ access opening

44‧‧‧ access opening

46‧‧‧Molded wall

48‧‧‧Molded wall

50‧‧‧ trench

52‧‧‧ arrow

54‧‧‧ wall thickness

56‧‧‧ sharp edges

58‧‧‧Conical inlet surface

60‧‧‧ External cracks

62‧‧‧External surface

64‧‧‧Cone

66‧‧‧External connection surface

68‧‧‧ fluid passage

70‧‧‧ access opening

72‧‧‧ access opening

74‧‧‧Linear surface

76‧‧‧ concave surface

78‧‧‧ planar annular surface

80‧‧‧Thrust elements

80'‧‧‧Thrust elements

82‧‧‧Closed system

84‧‧‧Semi-finished products

86‧‧‧ cylindrical extension

86’‧‧‧ cylindrical extension

The objects of the present invention will now be described in detail with the aid of such additional schema listings, wherein: Figures 1, 2 and 10 show three component objects of the invention in accordance with various embodiments; Figure 3 The two enlarged portions of the mold half shown in Figs. 1 and 2 are respectively shown in Fig. 4; Fig. 5 shows the precursor according to a change, and at the same time, Fig. 5a, Fig. 5b, and Fig. 5c A different embodiment of the end portion of the precursor is shown; Figure 6 is a diagram showing the pressure action between the closed molds of the forming device, and Fig. 6a shows an enlarged view of the emphasized area in Fig. 6; 7 and 8 show a side view and a cross-sectional view of a hollow metal body according to a possible embodiment, while Fig. 8a shows an enlarged view of the emphasized area in Fig. 8; and Fig. 9 shows the inside of the front body. The stroke (c) of the movable mold half is a function of the pressure pattern; and Fig. 11 shows that a semi-finished hollow metal body is obtained by the apparatus of Fig. 10.

Referring to the above-described schema list, the comprehensive indication of the component symbols 1, 1 ', 1" is used to form a component of a hollow metal body 2. The assembly is particularly suitable for forming spheres of ball valves, but can also be used for a further set of Hollow metal body.

The assembly 1, 1', 1" includes a precursor 4 of the metal body 2, which The precursor 4 includes a substantially tubular wall portion 6 that extends about a central axis X to define a body compartment 8. For example, the aforementioned precursor 4 is included only in the tubular wall portion 6.

Preferably, the precursor 4 is at least partially made of stainless steel according to the EN 10216-5 standard, preferably by thermal annealing. As an example, AISI 316L steel was found to be suitable for this purpose.

Unless otherwise specified, the terms "axial" and "radial" are used in reference to the central axis X in the context of the present disclosure.

Advantageously, the body compartment 8 is open to the two axial ends 4, 4" of the front body 4 by the opposite access openings 42, 44.

Referring to the specific embodiments shown in Figures 3, 4 and 5, the precursor 4 is characterized by having different axial lengths L ₀ (which are tubular walls parallel to the central axis X) The length of the portion 6), the different wall thicknesses s and the different passage portions of the body compartment 8.

Preferably, the tubular wall portion 6 defines a body compartment 8 having a substantially circular cross section (i.e., orthogonal to the central axis X).

The assembly 1, 1 ', 1" further includes a forming device 10, 10', 10" comprising at least a first mold half 14 and a second mold half 16, The semi-molds 14, 16 collectively define a mold cavity 18, wherein the mold cavity 18 preferably accommodates the precursor 4 in a reversible manner.

In fact, the precursor 4 is inserted into the mold cavity 18, Then, after the precursor has been transferred to the metal body by the operations described later, the metal body 2 is taken out from the chamber, and the mold chamber 18 is thus capable of accommodating a new precursor. To carry out a new formation process.

The forming device 10, 10', 10" discriminates one or more injection channels 12, 12' of a pressurized liquid in the body compartment 8 to induce expansion of the body compartment 8. For example, the liquid used For water or oil.

Advantageously, the injection channels 12, 12' are at least partially discernible by one of the mold halves 14, 16; according to one embodiment, the two molds identify a separate injection channel. For example, the channels 12, 12' at least partially pass through the thickness of a mold wall portion 46, 48.

Preferably, the injection channels 12, 12' are in communication with the at least one pressurized source 38, 40 of the pressurized liquid at the upstream end, which are only shown in the illustrated list, and the injection channels 12, 12' communicates with the mold cavity 18 at the downstream end. Since the precursor is located inside the chamber 18, and since the tubular wall portion 6 preferably forms a seal with the inner surfaces 30, 30' of at least one of the semi-molds 14, 16 The injection channels 12, 12' facilitate downstream termination to the inside of the body compartment 8. More practically, at least one of the outlets 20, 20' of the injection passages 12, 12' in the mold cavity 8 terminates at one of the access openings 42, 44 of the body compartment 8.

In the above case, the terms "upstream" and "downstream" refer to the direction of passage of the pressurized liquid.

In at least one of the operating conditions of the semi-molds 14, 16 described above, The equal molds 14, 16 are configured to control the plastic deformation of the tubular wall portion 6 after expansion of the body compartment. In effect, the tubular wall portion 6 is deformed outwardly by the pressurized liquid to gradually adhere to the inner surfaces 30, 30' defined by the mold halves.

Referring to the variant illustration in Figure 1, the forming apparatus 10 includes a pair of pressurized sources 38, 40, wherein the first source 38 is preferably used as feedback for the second source 40. For example, the second source of pressurization 40 includes a voltage doubler.

The forming device 10, 10', 10" further includes a plurality of axial compression means 14, 16; 80, 80' of the precursor 4 to deform the tubular wall portion 6 radially outwardly and to obtain the metal body 2 .

According to a first preferred variant, the axial compression means comprise at least one thrust element 80, 80' which is connected to at least one of the moulds 14, 16 and which is displaceable towards the mould cavity 18. To compress the precursor. More specifically, the displacement is not performed with respect to the semi-molds. Preferably, the injection channels 12, 12' are obtained at least in part within the thrust members 80, 80', such as shown in Fig. 10, so that they can be formed from a generally tubular profile.

According to a second preferred variant, the isoaxial compression device comprises at least one of the semi-molds (14 or 16) described above, which may be between an open configuration and a compressed configuration of the mold cavity 18, Moving relative to the other mold half (16 or 14), wherein the movable mold half 14, 16 axially compresses the precursor 4.

For example, in an open configuration in which the two mold halves are spaced apart from each other, In particular, it is sufficiently spaced to allow a precursor to be introduced into the mold cavity 18. Conversely, in the compressed configuration, the movable mold half 14, 16 axially compresses the precursor 4 - actually against the other mold half to deform the tubular wall portion 6 radially outwardly and obtain The metal body 2.

In other words, in this arrangement compression, such interior surface 30, 30 'facing the axial distance between the front body 4, lines less than the axial length L ₀ of the front body 4, and this generating said axial compression s reason. For this reason, the axial length L ₀ is a key parameter to ensure complete filling of the mold.

Therefore, it is novel that the metal body 2 is obtained by a combined action of the internal pressure of the pressurized liquid and the mechanical deformation of the movable half mold or the thrust element on the precursor 4. Accordingly, the metal system expands at least partially outwardly, meaning that at least one cross-section of the body compartment has increased relative to the initial conditions of the precursor.

In the particular embodiment illustrated in Figure 1, the semi-mold identified by the component symbol 14 is stationary and the other half of the mold 16 is movable in the approaching/away direction.

In the variant shown in Fig. 2, the two mold halves 14, 16 are movable relative to each other, for example, symmetrically with respect to a median plane Z.

In the variant shown in Fig. 10, there is no one or two movable semi-molds present - both technical solutions can be implemented according to this embodiment - at least one of the thrust elements 80, 80' is movable The bit pattern is accommodated in at least half of the molds 14, 16. Preferably, each of the molds includes the thrust element Pieces.

For a particular embodiment of the forming device 10" that provides a thrust element 80, 80', a closure system 82 can be provided that acts on at least the movable half-cast mode to ensure that the mold cavity is during liquid injection. The chamber 18 is closed.

Preferably, the movable mold half and/or the thrust members 80, 80' are movable parallel or coaxially with respect to the central axis X of the tubular wall portion 6.

In order to move the mold, the forming means 10, 10', 10" may comprise one or more linear actuators 32, 34, for example in electrical or hydraulic form.

According to a variation of Fig. 1, the forming device 10 includes only a linear actuator 32 to move the movable mold half by means of the shaft motion mechanism 36. According to a variation of Fig. 2, the forming device 10' can include two movable molds, each of which is urged by an opposing linear actuator 32, 34. Preferably, a first linear actuator 32 operates in relation to the action of the other actuator 34. According to a variation of Fig. 10, the thrust members 80, 80' and the movable molds 14, 16 can be moved by a different linear actuator.

According to a specific embodiment, at least one outlet 20, 20' (or a plurality of outlets thereof) of the injection channel 12, 12' is attached to a portion 22 of the mold half 14, 16 projecting in the mold cavity 18. obtain. According to the variant, when the movable molds 14, 16 are in the closed configuration of the mold cavity 18 (i.e., in a configuration in which the mold halves are adjacent to each other), the metal body is adjacent Connected to the portion 22 or the pair of portions 22, as illustrated, for example, in Figure 6.

More specifically, because the protruding portion 22 defines an annular groove 50 having its inner surface 30, 30', at the base of the portion 22 described above, in the closed configuration, the metal body 2 itself is embedded into the In the groove 50. In this regard, the inner surface 30, 30' can be partially concave to guide the metal body during insertion into the groove 50.

For example, as seen in Fig. 6, the arrow 52 indicates that the internal pressure action on the precursor is converted into the metal body, and both ends of the body 2 are inserted into the respective annular grooves. In the slot 50.

Therefore, it is easy to understand that the above-mentioned protruding portion 22 holds the fluid passage 68 in the metal body, and regardless of the degree of deformation of the precursor, the access openings 70, 72 of the fluid passage will still be due to the portion 22. Stay open.

Preferably, the annular groove 50 is defined by a substantially rectilinear surface 74 and an adjacent concave surface 76 extending away from the portion 22. For example, the surface is part of the inner surface 30, 30' of at least one of the semi-molds.

Accordingly, according to an advantageous variant, at the access openings 70, 72, the metal body can define an outer connecting surface 66 which actually has a shape complementary to the surface of the annular groove discussed above.

According to an advantageous embodiment, the tubular wall portion 6 comprises an end portion thickness s (which may be a middle thickness in the case of a fixed thickness of the wall portion) And at least one end portion of the thickness s is thinned by d. The end thinning d is provided to obtain a fluid seal with the respective semi-molds 14, 16.

According to a further advantageous variant, the front body 4 or the tubular wall portion 6 defines at least one conical inlet surface 24 which is inclined at an angle β with respect to the central axis X in the metal body 2 after the end of the deformation. A planar cylindrical surface 26 is obtained. For example, the angle β is in the range of 30°-70°, preferably 40°-60°, advantageously 45°-55°, for example substantially 50°.

Preferably, the planar cylindrical surface 26 is joined to the outer connecting surface 66 by a planar annular surface 78. For example, the planar cylindrical surface 26 and the planar annular surface 78 extend at a right angle to each other, as illustrated, for example, in Figure 8a or Figure 6a.

Referring to the specific embodiment of Figure 5a, a first 24 and a second 58 conical inlet surface are provided at opposite surfaces of the tubular wall portion 6, respectively - an inner surface and an outer surface. In the manner described, at least one of the shaft ends 4" of the precursor 4 has a sharp edge or a tapered edge 56.

Preferably, the metal body 2 is a spheroid having a substantially fixed wall thickness 54 and wherein the following triangular geometric relationship can be applied: Where: - L _finale (shown as " L _f " in Figure 8) is the final length of the spheroid; - D _int is the inner diameter of the spheroid; - α /2 is opposite the spheroid The average angle of the final length; - L ₀ is the axial length of the precursor 4 as defined above.

According to a variant, at least one of the shaft ends 4', 4" of the front body 4 is inclined radially inwardly or deformed into a conical shape, so that one of the end outer surfaces 28 is established with the semi-molds 14 The seal of the inner surface 30, 30' of at least one of the 16. The features are well illustrated in Figure 5c, wherein the taper 64 is shown to be prior to the movement of the moveable mold half.

For the deformation of the assembly of Fig. 10, since the deformation provides that the thrust elements do not penetrate into the mold cavity 18, the hollow metal body is achieved by means of a half of the finished product 84, the semifinished product 84 being At one of its axial ends there is at least one generally cylindrical extension 86, 86'. For example, Figure 11 shows the extensions being paired, extending in mutually opposite directions. Preferably, the extensions 86, 86' described above will be removed to obtain a metal body for use.

According to a further variant, the forming device 10, 10', 10" comprises the aforementioned pressurized sources 38, 40 which can be controlled such that: a) when the semi-molds 14, 16 are spaced apart, the source 38, 40 is adjusted to maintain a first fixed pressure P ₀ in the body compartment 8; and b) the source promotes the first pressure P ₀ to one after contact between the two mold halves 14 , 16 The increase in the pressure P ₁ .

The pressure trend is well shown in the graph of Figure 9, where the upper curve shows the movement of the movable mold, which is maintained constant at time t1 because the mold cavity is closed. In contrast, the lower curve shows this pressure trend, which maintains a constant value P ₀ during the time interval t0-t1 (that is, during the closing process of the above chamber), and then gradually rises to P during the time interval t1-t2 ₁ and then stably maintained at the constant value until time t3. Alternatively, after time t3 and before the moving semi-mold is moved back to the mold chamber again, the pressure can be lowered again (eg, to ambient pressure), which in effect avoids uncontrolled deformation of the metal body. .

For example, the above pressures P ₀ , P ₁ can be determined according to the following equation: Where: - R _{p 1.0} is the relief strength required for the precursor 4 to obtain 1% permanent deformation; - d _{int is} the inner diameter of the tubular wall portion 6; - s is the average thickness of the tubular wall portion 6; - k ₁ Is a numerical coefficient between 1 and 1.5, and it has sensitivity to ensure plastic deformation of the precursor and support of the tubular wall during closure of the semi-molds; - k ₂ is between 2 and 4 The numerical coefficient between and is particularly important to ensure correction of the working component and subsequent improvement of the mechanical properties of the hardened metal body.

The above object is further achieved by a procedure for forming a metal body 2, in particular for forming a sphere of a ball valve, the procedure comprising the steps of: Providing a precursor 4 of the metal body 2, comprising a substantially tubular wall portion 6 extending about a central axis X to define a body compartment 8; - injecting into the body compartment 8 a pressurized liquid to induce expansion of the body compartment 8; - controlling plastic deformation of the tubular wall portion 6 after the expansion; - axially compressing the precursor 4 such that the tubular wall portion 6 is radially outward The metal body 2 is deformed and obtained.

Since the described procedure can be advantageously implemented by the apparatus and components described above, the preferred or preferred embodiments of the present invention include any of the steps concealed by the foregoing structural features.

According to a particular embodiment, the step of providing a precursor includes the one or more tubular stem divided into a plurality of steps or the most part have an axial length L ₀ of, those parts corresponding to those described above approximately precursor.

In other words, the prior systems that can be used in the method and assembly can be separated into a desired size by a single tubular rod, such as by a cutting operation.

According to an advantageous variant, the injection and compression steps are carried out at least partially simultaneously.

According to a further advantageous variant, the injection step and/or the compression step is carried out in the case of a cold treatment, that is to say without heating. For example, one or both of the steps can be carried out at room temperature. In fact, due to the cold treatment, the metal body is strengthened by the hardening condition formed.

Optionally, the injecting step includes a first injection sub-step of pressurized liquid at a first fixed pressure P ₀ and increases the first pressure P ₀ to a second pressure P ₁ when the compressing step is completed. For the determination of the values of the pressures P ₀ and P ₁ , reference may be made to the previous description.

According to further embodiments, the program may include one or more docking operations of the precursor and/or a step of forming an external crack 60 on the metal body.

For example, the end thinning d, the one or more conical inlet surfaces 24, 58 and/or the conical shape of the axial ends 4', 4" can be formed using a butt joint.

As for the outer crack 60, it may actually be arranged to receive an operating rod (not shown) that can be actuated by a user lever to rotate the spherical metal body inside a valve body to allow/avoid The liquid inside the valve passes through. By way of example, the outer crack 60 can be made by mechanical debris removal or laser removal/cutting. According to a further variant (not shown), the external crack can be performed by means of a shearing step performed by suitable functional interaction between the appropriate means and the mold cavity 18. According to the deformation, for example, the pressure inside the metal body can be maintained to resist an internal force against the external mechanical force applied by the shearing.

According to a further variant, the metal body can perform a grinding step of the outer surface 62 of the metal body 2 (for example, which aims to obtain a satisfactory circular shape or a desired outer contour/diameter), and/or external to the metal body At least one of the cleaning steps of the surface, in particular for obtaining a desired surface finish. Alternatively, the step of at least partially removing the cylindrical extensions 86, 86' (when provided), and a grinding step and/or a brushing step of selectively removing the residual portions of the action may be provided.

For example, the grinding step can be carried out using a cup-shaped grinding wheel or by a pressure-damping grinding wheel.

Advantageously, the component or program of the present invention achieves significant advantages in terms of cost.

In fact, the present invention provides significant savings in the original material when the same number of metal bodies are made, as the ball valves do not require post-treatment to eliminate more material.

In addition, thinness and maintaining a fixed metal body wall thickness over the overall length can reduce the amount of metal material needed to make the body.

Furthermore, the above described devices are simple to construct, so they can reduce the amount and complexity of the equipment used. In particular, with respect to past molding devices, the device of the present invention aims to reduce the components associated with the pushers in which the fluid passages are formed. Furthermore, it is possible to exclude the pressing in order to keep the molds closed.

Advantageously, the apparatus and program of the present invention are capable of obtaining a hollow body in an extremely reproducible manner with excellent dimensional tolerances.

Advantageously, the apparatus of the present invention is directed to ensuring a seal during a complete forming cycle before or after closure of the mold halves.

Advantageously, the assembly objectives of the present invention are capable of achieving greater propulsion power using the same technical configuration and ensuring mechanical closure of the molds without the use of automated mechanical techniques.

Advantageously, by using an electric motor, high accuracy can be achieved throughout the duty cycle.

Advantageously, the components and program targets of the present invention provide other originals The use of materials to make spheres for ball valves, especially metal materials that do not require electroplating.

In fact, the nickel-free order is about to take effect, which will force manufacturers to be responsible for completing their work in a nickel-free way in traditional nickel-chromium coating systems that currently sell copper balls on the market.

Advantageously, the previously discussed thermal parameters can advantageously affect the metal cost, so that the elements ensure the required mechanical properties and also ensure a wall thickness that is less than that of conventional metal bodies.

Advantageously, the fluid passage inlets of the metal body are specifically designed to avoid any damage to the fluid seals that integrate the outside of the body. This result increases the life of the valves compared to conventional spheres.

Advantageously, the above described procedures are designed to always operate under safe conditions and to ensure a high degree of reproducibility of such forming operations.

Those skilled in the art can make many component changes or substitutions for the specific embodiments of the above components, programs, and precursors to other components having equivalent functions to meet specific needs.

Again, the variants are also included in the scope of protection defined by the claims below.

Moreover, each variant described as belonging to a possible embodiment can be practiced independently of the other variations described.

1’‧‧‧ components

4‧‧‧ precursor

10’‧‧‧ forming device

12‧‧‧Injection channel

12’‧‧‧Injection channel

14‧‧‧Half mold

16‧‧‧Half mold

20’‧‧‧Export

22‧‧‧Parts

30‧‧‧Internal surface

30’‧‧‧Internal surface

32‧‧‧Linear actuators

34‧‧‧Linear actuator

38‧‧‧ Pressurized source

40‧‧‧ Pressurized source

46‧‧‧Molded wall

48‧‧‧Molded wall

Claims (18)

An assembly (1, 1 ', 1") for forming a hollow metal body (2), in particular a sphere for forming a ball valve, the assembly comprising: i) a precursor of the metal body (2) (4) The precursor (4) comprises a substantially tubular wall portion (6) extending about a central axis (X) to define a body compartment (8); and ii) a forming device (10, 10', 10"), the forming device (10, 10', 10") discriminates one or more injection channels (12, 12') of a pressurized liquid in the body compartment (8) to induce Expansion of the body compartment (8), and the forming device (10, 10', 10") includes at least a first (14) and a second (16) mold half that together define the precursor (4) a molding cavity (18) and configured to control plastic deformation of the tubular wall (6) after expansion; wherein said means (10, 10', 10") comprise a plurality of axes of the precursor (4) The compression device (14, 16; 80, 80') is such that the tubular wall portion (6) is deformed radially outward to obtain the metal body (2). The assembly of claim 1 wherein the axial compression means comprises at least one of the mold halves (14; 16) in an open configuration and a compression configuration of the mold chamber (18) Moving relative to the other half of the mold, the movable mold half (14; 16) axially compresses the precursor (4). The assembly of any of the preceding claims, wherein at least one outlet (20, 20') of the injection channel (12, 12') or a plurality of outlets thereof is attached to the mold half (14; 16) Obtained from a portion (22) of the chamber (18) Wherein, when the movable mold half (14; 16) is in the closed configuration of the mold cavity (18), the metal body position is adjacent to the portion (22). The assembly of claim 3, wherein the protruding portion (22) defines an annular groove (50) having an inner surface (30, 30') of the semi-molding mold (14, 16), the annular groove (50) is defined by a substantially rectilinear surface (74) and an adjacent concave surface (76) extending away from the portion (22), the metal body defining a shape complementary to the groove An external connection surface (66). The assembly of claim 1 wherein the axial compression means comprises at least one thrust element (80, 80') coupled to at least one of the molds (14; 16) and Displacement toward the mold cavity (18) to compress the precursor. The assembly of any of the preceding claims, wherein the tubular wall portion (6) comprises an end portion thickness (s) or an intermediate thickness, and at least one end portion that thins the thickness (s) (d), A fluid seal is obtained to identify the at least half of the molds (14, 16) of the injection channel (12, 12'). The assembly of any of the preceding claims, wherein the precursor (4) or the tubular wall (6) defines at least one conical inlet surface (24) at an angle ( β ) The central axis (X) is tilted to obtain a planar cylindrical surface (26) in the metal body (2). The assembly of claim 7, wherein the angle ( β ) is in the range of 30°-70°, preferably 40°-60°, advantageously 45°-55°, for example substantially 50. °. The assembly of any of the preceding claims, wherein the metal body (2) is a spheroid having a substantially fixed wall thickness (54), and wherein the following triangular geometric relationship is applicable: Wherein: - L _finale is the final length of the spheroid; - D _int is the inner diameter of the spheroid; - α /2 is the average angle against the final length of the spheroid; - L _{0 is} the precursor (4) The axial length. The assembly of any of the preceding claims, wherein at least one of the shaft ends (4'; 4") of the precursor (4) is inclined radially inward or deformed into a conical shape, such that the end One of the outer surfaces (28) of the portion establishes a seal with the inner surface (30; 30') of at least one of the semi-molds (14; 16). An assembly according to any of the preceding claims, wherein: - the forming device (10) comprises a linear actuator (32) for moving the movable semi-molding mold (14) by means of an axis motion mechanism (36); 16); - the forming device (10') comprises two movable semi-molds (14, 16), Each is electrically or hydraulically driven by its own linear actuator (32, 34); or the forming device (10") includes at least one thrust element (80, 80') that is displaceably received In at least half of the molds (14, 16), the elements (80, 80') and the movable mold half (14; 16) are moved by a different linear actuator. The assembly of any of the preceding claims, wherein the forming device (10, 10', 10") comprises at least one pressurized source (38, 40) of the pressurized liquid, and wherein the semi-molds ( 14, 16) when spaced apart, the source (38, 40) is adjusted to maintain a first fixed pressure ( P ₀ ) in the body compartment (8), and wherein the two mold halves (14) After the contact between 16), the source promotes an increase in the first pressure ( P ₀ ) to a second pressure ( P ₁ ). The component of claim 12, wherein the pressure ( P ₀ , P ₁ ) is determined in the following manner: Where: - R _{p 1.0} is the relief strength required for the precursor (4) to obtain 1% permanent deformation; - d _{int is} the inner diameter of the tubular wall portion (6); - s is the tubular wall portion (6) Average thickness; - k ₁ is a numerical coefficient between 1 and 1.5; - k ₁ is a numerical coefficient between 2 and 4. The assembly of any of the preceding claims, wherein the precursor (4) is at least partially made of stainless steel according to the EN 10216-5 standard, such as AISI 316L steel that has been thermally annealed. A procedure for forming a hollow metal body (2), in particular a sphere for forming a ball valve, the procedure comprising the steps of: providing a precursor (4) of the metal body (2) comprising a substantially tubular wall a portion (6) extending with respect to a central axis (X) to define a body compartment (8); - injecting a pressurized liquid into the body compartment (8) to induce the body Expansion of the compartment (8); - controlling plastic deformation of the tubular wall portion (6) after the expansion; - axially compressing the precursor body (4) to deform the tubular wall portion (6) radially outward And the metal body (2) is obtained. The program of claim 15 wherein the injecting and compressing steps are performed at least partially simultaneously. The procedure of claim 15 or 16, wherein the injecting step and/or the compressing step is performed without heating, such as at room temperature. The process of any one of claims 15 to 17, wherein the injecting step comprises a first injection sub-step at a first fixed pressure ( P ₀ ) and increasing the first pressure upon completion of the compressing step ( P ₀ ) to a second pressure ( P ₁ ).