WO2020050732A1

WO2020050732A1 - Monobloc or compact ball valve with integrated sealing and process for manufacturing the same

Info

Publication number: WO2020050732A1
Application number: PCT/PT2018/050028
Authority: WO
Inventors: António Carlos TORRES; Pedro Miguel GODINHO MATOS
Original assignee: Fortlev Indústria E Comércio De Plásticos Ltda; Okmoldes Unipessoal ,Lda
Priority date: 2018-09-06
Filing date: 2018-09-06
Publication date: 2020-03-12
Also published as: BR112018074464A2

Abstract

The present invention relates to a monobloc or compact ball valve with integrated sealing and comprises as its internal component a ball/sealing assembly having as its centrepiece an injected ball, with a through hole, which makes the ball cast and a radially spherical hollow core which results in a constant wall thickness. From the outer surface of the ball and perpendicularly to the through hole, a circular base rod extends, which at a certain length has three flat faces. A tubular-shaped thermoplastic sealing element is integrated over the said ball, located at the two outer ends generated by the short-length through hole, opposite each other and interconnected by straps that circumvent the ball and turn the sealing into a single element.

Description

MONOBLOC OR COMPACT BALL VALVE WITH INTEGRATED

SEALING AND PROCESS FOR MANUFACTURING THE SAME

DESCRIPTION

FIELD OF THE INVENTION

The present invention fits in the area of hydraulic installations, Civil Construction, in particular of ball valves, more specifically in ball valves and monobloc preferably in plastic.

BACKGROUND AND BACKGROUND OF THE INVENTION

Ball valves are selected for water distribution projects where the project requirements require a valve solution that allows efficient and lasting operations, frequent opening and closing of taps, as well as the control of the flow of water or other liquids . Since these valves are characterized by their spherical shape, they are suitable valves and are used in flow control when it is necessary to regulate the flow and pressure of a fluid. This flow control occurs because, by turning the handle that turns the sphere inside the valve, and being the hollow sphere, the passage of liquid inside the sphere decreases gradually, until reaching a closed position, in which the flow ceases due to the obstruction of the water passage.

Conventional monobloc or compact ball valves with the function of restricting and opening the flow of fluids are known in the conventional technique, constituted by a generally spherical, tubular body, provided with two lateral extensions for interconnection with the piping, and inside it , has a sphere (3) that extends in the form of an outward rod, where the steering wheel (1) fits, this sphere being provided with a through hole that, when aligned with the holes in the lateral extensions of the body (4), allow the passage of water, this being the open position. To close, simply turn the handwheel 90 ° so that the hole for the ball to pass is in a position transversal to those mentioned in the body extensions (4).

For the manufacturing process of these ball valves, one of the most efficient plastic processing techniques is certainly injection molding. The process consists of heating a plastic material to its melting point, in a cylinder surrounded by thermal resistances. A spindle works inside the hot cylinder, which transports the material to the front area of the cylinder. After that, the material will be injected by the axial movement of the spindle that pushes the melted plastic material and forces it to enter the mold cavities where the material is injected and where it cools down, assuming its final shape. Finally the mold is opened and the plastic is extracted. The process allows extremely high and consistent production rates, being the most efficient process for the production of highly complex plastic parts.

These valves are manufactured by the over-injection process where the internal components, the sphere and the two seals (2) are surrounded by the molten plastic material, normally PVC (Polyvinyl Chloride) and which after removing the heat solidifies forming the body (4) as shown in Figure 1.

These compact valves obtained by the over-injection process are characterized by having a single body (4), monobloc, with fewer components when compared to other valves, so they are also commonly called compact ball valves. Over-injection has already been used in the manufacture of valves, as shown in patent document DE4442979.

The thermoplastic seals (2) commonly used in compact ball valves are individual components introduced into the injection mold as inserted for the over-injection process of the valve body. The contact region (5) of these seals on the sphere component is severely affected by the geometric imperfections resulting from the injection process, which are common defects caused by the contraction of the thermoplastic material, mold geometry and process condition.

These same defects also affect the sphere component which has variable thickness (6) and with a great concentration of mass that results in uneven volumetric contractions and, consequently, an imperfect spherical geometry and to circumvent these imperfections in the sphere, it is common to use expensive sub -processes like removing material from the surface to make it uniform.

These spheres, when in the closed position and internally pressurized, have their tightness dependent only on a small vertex (7) of the thermoplastic seal when in contact with the surface of the sphere. It is an insufficient characteristic and that often does not fully guarantee the tightness, compromising the resistance of the valve to hydrostatic pressure because it depends only on this small point of contact, the vertex (7).

Also the manufacturing process of compact ball valves molded by over-injection, presents problems when the volumetric contraction of the mass of the body that involves the internal components, submits them to constriction (Figure 5) which due to the normal contraction of the plastic of the body , usually in PVC (Polyvinyl Chloride), generates a phenomenon of adhesion between body and sphere, which makes a second stage to the manufacturing process necessary, the stage of detaching the sphere during cooling of the body, which consists of the rotation of the sphere, if this is not done, it will prevent the movement of the sphere in its application.

In this same process, there is a need to handle two seals, each one being allocated at one end of the sphere, causing an increase in the loading time of these components when allocated in the injection mold.

In view of the aforementioned product and process problems, the present invention arose a monoblock or compact ball valve with an integrated seal that adds innovations focused only on the body of the monoblock ball valve (Figure 6) and improvements to eliminate some deficiencies detected in the available valves in the market.

BRIEF DESCRIPTION OF THE FIGURES

INDICATION OF REFERENCE NUMBERS:

^■ steering wheel (1);

^■ seals (2);

^■ conventional monobloc sphere (3);

^■ body (4);

^■ contact region (5);

^■ variable thickness indication (6);

^■ vertex of the seal (7);

^■ contact region (9) sphere (15);

^■ seal (10); ^■ surface (11) molding the ball (15);

^■ straps (12);

^■ ends (14) of the ball (15);

^■ body (17).

Figure 1 - Components of the state-of-the-art compact ball valve: handwheel (1), body (4), ball (3) and seals (2).

Figure 2 - Contact region (5) of the seals (2) with the ball (3).

Figure 3 - Sphere (3) with variable thickness.

Figure 4 - Detail of the seal vertex (7) in contact with the sphere (3).

Figure 5 - Constriction of the body (4) on the components.

Figure 6 - Representation of the present invention, of the compact monoblock ball valve (15) with integrated seal (10).

Figure 7 - Integrated ball valve (15) / seal (10) assembly, preferably the seal (10) is made of tubular-shaped thermoplastic material, located at the two external ends generated by a through hole, opposite each other themselves and interconnected by straps (12) that surround the sphere and make the seal a unique element.

Figure 8 - Sphere (15) with constant thickness and with mass relief.

Figure 9 - Collapsible release system.

Figure 10 - Detail of the contact region (9) with the enlarged sphere, in the closed position.

Figure 11 - Detail of the region (9) of contact between the seal (10) and the ball (15).

Figure 12 - Surface (11) molding the sphere, positioned on the ends (14).

Figure 13 - opposite ends of the sphere, where (15) represents the sphere - contraction between 1.3% / 2%; (10) the seal

- contraction between 1.3% / 2%; and (17) the pvc body - contraction 0.5 - 0.7%. Note that the contraction differences between sphere and body are on average 1%, which allows the sphere to rotate.

Figure 14 - It represents the section of a three-dimensional perspective view of the valve sphere according to the present invention. DESCRIPTION OF THE INVENTION

The present invention relates to a monobloc or compact ball valve with an integrated seal (10) and has as its internal component a ball (15) / seal (10) assembly, which has as its central part an injected ball (15) with a hole through, which makes the sphere (15) hollow and the radially spherical hollow core which results in a constant wall thickness. From the outer surface of the sphere (15) and perpendicular to the through hole, a circular base rod extends which in a certain length has three flat faces.

On this sphere (15) is integrated a thermoplastic sealing element (10) of tubular shape, located on the two outer ends (14) of the sphere (15) generated by the short hole, opposite each other and interconnected by straps ( 12) that surround the sphere (15) and make the seal (10) a unique element.

The present invention receives, through insertion, a single ball (15) / seal (10) set (Figure 7), different from traditional valves that receive individual seals. The contact region (9) between sphere (15) and the seal (10) is perfect, that is to say continuously adjacent, since the thermoplastic seal (10) is molded directly on the surface of the sphere (15), so it is not affected by geometric imperfections in this region. Additionally, the sphere (15) has a constant thickness and a mass-relieving core (Figure 8), which makes the geometry of this component stable and free from dimensional variation. It is possible to obtain this characteristic due to the application of an innovative collapsible mechanism that allows the demoulding of the internal region of the sphere as shown in figure 9.

The constant thickness of the sphere (15) is extremely advantageous because it standardizes the contraction, eliminates ovalization and deformations, thus eliminating the need for the machining sub-process to smooth the surface, removing the aforementioned material. It is added that by having a constant thickness, removing material through this system, it increases the tendency to its uniformity, thus achieving a more circular sphere (15), that is, uniform and constant, since there is no deformation, it improves the over-injection process and its handling will also be facilitated, on the other hand the removal of raw material reduces the costs associated with material consumption.

In the present invention, the contact region (9) of the thermoplastic seal (10) with the ball (15) is more generous and when in the closed position, the product's water tightness capacity is increased when subjected to hydrostatic pressure, since it does not there is contact vertex. The present invention eliminates the effect of constricting the PVC body (17) against internal components. The ball (15) / seal (10) assembly with a partial contraction is inserted into the mold, undergoes the process of over-injecting the body (17) and reaches full contraction only after complete cooling. The combination of raw materials with distinctive characteristics and polymeric contraction, allows the sphere (15) to be free to contract totally and freely in a greater proportion than the PVC body (17). This effect ensures that the ball (15) rotates freely within the body (17) without the need for a second step to perform the detachment.

The present invention reduces the number of seals from two seals to just one integrated seal (10) which consequently reduces the loading time of this component in the injection mold, thus optimizing the injection process.

The present invention presents as an internal component - a ball (15) / seal (10) (Figure 7) set, which has as its central part an injected ball (15), with a through hole, or through hole, which makes the ball (15 ) hollow and radially spherical hollow core that results in a constant wall thickness.

From the outer surface of the sphere (15) and perpendicular to the through hole, a circular base rod extends which in a certain length has three flat faces. A sealing element (10) is integrated over this sphere (15) tubular-shaped thermoplastic, located at the two outer ends (14) generated by the short length through hole, opposite each other and interconnected by straps (12) that surround the sphere (15) and make the seal a unique element.

The present invention has an exclusive sealing region where the contact surface (9) of the thermoplastic seal (10) with the ball (15), has the same shape as the surface of the ball (15) when in the equivalent position of the open valve. It is possible to reproduce this contact surface (9) perfectly with only an injection mold, since the ball (15) itself is used for insertion and the thermoplastic seal (10) is injected over it.

To produce the present invention, a sphere (15) injected thermoplastic in partial volumetric contraction stage that is introduced as an injection mold insert that receives the over-injection of a thermoplastic seal (10), forming a single spherical / seal . Through a second over-injection, this set is introduced into another mold responsible for forming the PVC body (17), which is also over-injected, bypasses the ball (15) / seal (10) set thus forming, the body (17) of the monobloc valve. After complete cooling and total volumetric contraction of all components, the ball (15) is without any surface adhesion with the body (17) and the seal (10), being completely free to rotate. Thus, the compact ball valves with integrated sealing, object of the present invention, with a single ball / seal assembly (figure 7), has a hollow injected sphere (15) with constant wall thickness as the centerpiece (Figure

8), internally shaped by a collapsible mechanism (figure

9) and with a seating region (9) in which a seal (10) is molded directly on the surface (11) of the ball (15), which is on the ends (14).

Having a single sealing element (10) at the two ends (14) of the sphere (15), opposite and interconnected by straps (12) that surround the sphere (15) the present invention has a smaller number of components. It also has an increased hydrostatic tightness when closed (Figure 10), and has a contact region (9) of the thermoplastic seal (10) with the ball (15) uni forma.

The present invention, with free rotation of the ball (15) inside the body (17) and without adhesion between the internal components, ensures that the ball rotates free inside the body (17) without the need for a second step to perform the detachment. In fact, the body (17), preferably of PVC, injected over the partially contracted sphere / seal (Figure 7), limits the constriction on the ball / seal assembly (Figure 7) allowing the sphere to contract completely and freely in greater proportion than the PVC body (17). It should be noted that the fact that the present invention has an integrated seal, facilitates both the sealing and the automatic manufacturing process of the valves, since the fact that both seals are interconnected makes human intervention unnecessary for them to be placed.

On the other hand, the integrated seal (10) has a double seal, which seals against the ball (15) at the water inlet and on the opposite side, since when the pressure is applied, the ball is pushed a second time against the second seal (in this case interconnected).

Another innovation and effect of the present invention is that this seal (10) partially covers the sphere, facilitating its handling, among others, as having less material, less adhesion, etc. In this case, this type of seal is more advantageous than the others in the state of the art, since the ball (15) goes against the seal (10) and is buried, in this case the ball (15) when giving the pressure of the water touches the rubber seal (10) and also the PVC surface in the situation when it is closed, facilitating handling at high pressure. In known valves the seal completely covers the ball, generating other problems. In short, the ball is free to rotate due to the interlocking seal that partially covers the ball and beyond. In short, the present invention has a tubular body (17), provided with two lateral extensions, and inside, an internal component formed by a set consisting of an injected spherical centerpiece (15), with a through hole which forms two ends (14) external opposite each other and that when aligned with the holes in the lateral extensions of the body (17), allow the passage of water. It also has a rod with a circular base, which in a certain length has three flat faces, which extends from the outer surface of the sphere (15) and perpendicular to the through hole and where a handwheel fits.

In order to achieve the stated technical effects, it differs in that the sphere has a radially spherical hollow core with a wall of constant thickness and its ends (14) are interconnected by straps (12) that surround the surface of the sphere (15). It is essential that the thermoplastic sealing element (10) of tubular shape, is molded directly on the surface of the sphere (15) and located at the two outer ends (14) promoting a contact region (9) between sphere (15) and the element seal (10) continuously adjacent and a free rotation of the ball (15) with the body (17).

The manufacturing process of the monoblock or compact ball valve object of the present invention must include the following steps:

• injection of thermoplastic ball (15); • introduction of the sphere (15), as insertion in an injection mold in partial volumetric contraction stage;

• reception of over-insertion of a thermoplastic seal (10);

• formation of a single sphere assembly (15) / seal

(10);

• introduction of the single ball (15) / seal (10) set according to the mold;

• over-injection, over the single ball (15) / seal (10), contour of the ball (15) / seal (10) set thus forming the PVC body (17) of the monobloc valve.

• complete cooling and total volumetric contraction of all components.

Claims

RE IVICATIONS

1. Monobloc or compact ball valve with integrated seal consists of a tubular body (17), with two lateral extensions, and inside, an internal component formed by a set consisting of an injected spherical central part (15), with a through hole which forms two external ends (14) opposite each other and which, when aligned with the holes in the lateral extensions of the body (17), allow the passage of water; and circular base rod that, in a certain length, has three flat faces, which extends from the external surface of the sphere (15) and perpendicular to the through hole and where a steering wheel, characterized by

a) the sphere has a radially spherical hollow core with a wall of constant thickness;

b) the ends (14) are interconnected by straps (12) that surround the surface of the sphere (15);

c) present a tubular-shaped thermoplastic sealing element (10), molded directly on the surface of the sphere (15) and located on the two outer ends (14) promoting a contact region (9) between sphere (15) and the seal (10) continuously adjacent and a free rotation of the ball (15) with the body (17).

2. Monobloc or compact ball valve according to the previous claim, characterized in that the balls (15) and the body (17) are made of raw materials with different polymeric contraction and characteristics.

3. Manufacturing process for the monobloc or compact ball valve described in claims 1 and 2, characterized by the following steps:

a) injection of a thermoplastic sphere (15);

b) introduction of the sphere (15), as insertion in an injection mold in partial volumetric contraction stage; c) receiving the over-injection of a thermoplastic seal (10);

d) formation of a single sphere set (15) / seal

(10);

e) introduction of the single ball assembly (15) / seal

(10) second mold;

f) over-injection, on the single ball assembly (15) / seal (10), contour of the ball assembly (15) / seal (10) thus forming the PVC body (17) of the monobloc valve.

g) complete cooling and total volumetric contraction of all components.