FR3087685A1 - METHOD OF MANUFACTURING A SEALING ASSEMBLY FOR CONTROLLING THE FLOW OF FLUID FLOWS - Google Patents

Abstract

The invention relates to a method of manufacturing a sealing assembly, comprising the following steps: a) providing a hollow body (34) comprising a seat (12 ') having an annular receiving surface (16') and a shutter (14 ') having a shutter surface (20'); and, b) installing said shutter (14 ') inside said hollow body (34). Said method comprises between steps a) and b) the sub-steps: α) a radial marker (48, 50) is carried on said seat (12 ') and on said shutter (14'); β) the topography of said annular reception (16 ') and closure (20') surfaces is recorded in order to be able to establish virtual reception and closure surfaces; γ) simulating the contacting of said virtual reception and closure surfaces, and the total volume of free space between the two virtual surfaces is evaluated; δ) the relative angular position of said radial marks is recorded in which the total volume of free space is minimal for installing said shutter (14 ').

Description

Method of manufacturing a sealing assembly for controlling the flow rate of fluid flows The present invention relates to a method of manufacturing a sealing assembly suitable for controlling the flow rate of fluid flows and to an assembly of sealing obtained according to the method.

One field of application envisaged is notably, but not exclusively, that of thermal installations.

Known devices make it possible to control the flow of fluids, liquid or gaseous, in various installations.

These devices usually include a metal hollow body inside which a seat is provided, i.e. a circular bearing surface surrounding an opening, while a shutter, also metal, located inside the hollow body and adjustable from the inside. 'exterior, is able to come to rest in the seat to close the opening.

Thus, when the shutter is moved away from the seat, the fluid flows normally through the hollow body which connects for example two pipe ends, and when it is resting in the seat, the flow of the fluid is interrupted.

Also, the quality of the seal between the shutter and the seat depends in particular on the surfaces in contact and also on the pressure of the surfaces against each other.

In order to complete this seal, it is customary to install an elastomer seal between the two surfaces so as to be able to compensate for surface irregularities.

However, such seals cannot be used in high pressure thermal installations, for example nuclear installations, because they would not withstand the imposed stresses.

They could not be used either in installations at low temperatures or even with chemically aggressive fluids.

Consequently, the seal must be ensured by the metal / metal contact alone, between an annular surface of the seat surrounding the opening and a sealing surface of the shutter.

Consequently, the manufacture of the sealing assemblies requires a particular machining of these two surfaces in order to obtain the sealing, and as “smooth” as possible.

Nevertheless, whatever the precautions taken, the contact zone between the annular surface of the seat and the obturator surface of the shutter, reveal free spaces.

These 2 free spaces, also called together "opening field, remain whatever the pressure exerted to apply the surfaces against each other."

It is also well known that the loss of tightness in such circumstances is a cubic function of the “opening field”.

Also, a problem which arises and which the present invention aims to solve is to provide a method of manufacturing a sealing assembly comprising two metal surfaces adapted to come into contact with one another, which makes it possible to significantly reduce sealing losses between the two surfaces.

To this end, a method is proposed for manufacturing a sealing assembly suitable for controlling the flow rate of the fluid flows, comprising the following steps: a) on the one hand, a hollow body is provided comprising a seat having a surface rough annular receiving surrounding an opening and on the other hand, a shutter having a rough shutter surface adapted to come to rest against said rough annular receiving surface; and, b) said shutter is installed inside said hollow body facing said seat.

The method further comprises, between steps a) and b), the following substeps: a) a radial mark is placed on said seat and on said shutter; f3) the topography of said annular receiving and sealing surfaces respectively with respect to said radial marks is recorded in order to be able to establish virtual receiving and sealing surfaces; y) the contacting of said virtual receiving and shutter surfaces is simulated, and the total volume of free space between the two virtual surfaces is evaluated, in each of the 360 ° / p relative angular positions angularly offset from one another. others of pitch p, p> 0; ô) the relative angular position of said radial marks is recorded in which the total volume of free space is minimal; and in step b) said shutter is installed in said relative angular position of said radial marks recorded with respect to said seat.

Thus, a characteristic of the invention resides in the recording of the topographies of the annular receiving and sealing surfaces, and in the examination of the possible cooperation of these two surfaces bearing against each other with the aim of to minimize the total volume of free spaces, ie the 3 “opening field”.

The examination of these possibilities is carried out from the virtual representation of surfaces.

Indeed, whatever the machining precautions, the actual surfaces used exhibit irregularities or defects showing hollows and peaks 5 distributed more or less homogeneously and of different amplitudes.

The invention thus aims to record these defects as precisely as possible in order to then be able to adjust the two surfaces against one another, so that the majority of the vertices of one of the surfaces coincide with the hollows of the other surface and vice versa.

In this way, the free spaces are minimized and the tightness of the assembly is considerably improved.

According to a particularly advantageous embodiment of the invention, said annular receiving and sealing surfaces are respectively machined between sub-steps a) and (3).

In other words, the radial marks are first respectively placed on the seat and on the shutter, and on the periphery of the annular receiving surface and of the shutter surface, before proceeding with the machining.

Also, care is taken not to alter the radial marks, for example grooves, during machining.

And we proceed to the registration of topographies after machining.

According to an advantageous characteristic of the invention, the radial marks of said seat and of said shutter are respectively oriented in a given direction when said annular receiving and shutter surfaces are machined.

Such a precaution is aimed at the production of the sealing assemblies in series.

In fact, surface defects appear during machining, and they are relatively constant for the same machining mode.

Therefore, and as will be explained in more detail below, for the manufacture of a series of sealing assemblies, all the steps of the method according to the invention can be carried out for a single sample of this series and then, for other seals in the series, omit steps, a), (3), y) and ô).

According to an alternative embodiment, in step 0.), a plurality of concentric circular profiles of said annular reception and closure surfaces are respectively measured in order to be able to record their topography.

The topography of the real surfaces involved is difficult to access.

4 Also, some approximations are made and according to this variant, the topography of the surface is determined according to a plurality of concentric circular lines regularly spaced from the inside of the annular receiving surface to the outside of the receiving surface. annular of the seat, and in parallel, of the closure surface of the shutter adapted to come into contact with the annular receiving surface.

In this way, a good approximation of the surface condition can be obtained and thus the topography can be recorded.

According to another variant embodiment, in step 13), a plurality of radial profiles of said annular reception and closure surfaces are respectively measured in order to be able to record their topography.

According to this variant embodiment, the topography is accessed by measuring a succession of profiles of the surfaces along radii uniformly distributed over all of the surfaces.

Also, the measurement of the profiles, ie the height of the vertices and the hollows of the surface along a line, is advantageously carried out by contact; by means of a profilometer for example, equipped with a diamond tip.

The tip is then secured to a sensor which registers its vertical position when the tip is driven against the surface.

Preferably, the profiles are measured optically.

Indeed, thanks to optical sensors one obtains a better resolution and better definitions of the surface profiles.

Consequently, the topography is recorded more precisely, which is then closer to the real surface.

Also, the recorded topographies, marked respectively with respect to the radial marks, comprise pluralities of points marked by their coordinates in space.

In this case, the points can be easily located in a cylindrical coordinate system.

Thus, in step p), said virtual reception and obturation surfaces are established, preferably by interpolation.

By bilinear interpolation, for example, it is possible to calculate the height of the surface at a point from its two closest neighbors, the coordinates of which are known.

In addition, in a particularly advantageous manner, the total volume of free space between the two virtual surfaces is evaluated, in each of the 360 ° / p relative angular positions angularly offset from each other by the pitch p, where p is between 0.5 and 5, for example 1.

360 evaluations of the total volume of the free spaces between the two virtual surfaces are then carried out.

If we consider that the surface defects have a frequency of the order of a millimeter, and that for example the diameter of the seat is 10 cm, the offset of a pitch being close to a millimeter at the level of the annular surface. , it is consistent with the frequency of faults.

Also, and according to another aspect, there is proposed a sealing assembly suitable for controlling the flow rate of the fluid flows, obtained by a manufacturing method as described above.

More generally, the seal assemblies are produced in series, and they are thus matched with their corresponding radial marks.

And each assembly will thus be provided with an indication of the angular position of the hollow body and of the shutter to be adopted by associating them, based on the radial marks.

Other features and advantages of the invention will emerge on reading the description given below of particular embodiments of the invention, given by way of indication but not limiting, with reference to the appended drawings in which: - the Figure 1A is a schematic view in axial section of a sealing assembly manufactured in accordance with the invention; - Figure 1B is a schematic top view of the sealing assembly illustrated in Figure 1A; - Figure 2 is a detailed schematic sectional view of the sealing assembly shown in Figure 1; Figure 3A is a detailed schematic view of the object of Figure 2 in a first position; - Figure 3B is a detailed schematic view of the object of Figure 2 in a second position; - Figure 3C is a detailed schematic view of the object of Figure 2 in a third position; - Figure 4 is a flowchart of the method of manufacturing a sealing assembly according to the invention; 6 - Figure 5 is a schematic cut-away view of an element of a sealing assembly; - Figure 6 is a schematic view of another element of the sealing assembly; and, 5 - Figure 7 is a schematic cut-away view of the two elements of Figures 5 and 6, assembled.

Figure 1A illustrates in axial section a sealing assembly 10 comprising a seat 12 and a shutter 14.

The seat 12 has an annular receiving surface 16 surrounding an opening 18.

The annular receiving surface 16 is here flat.

In other words, it extends according to a plan.

The shutter 14 has a shutter surface 20 able to come to rest against the annular receiving surface 16 so as to be able to close the opening 18.

Thus, for example, the seat 12 is provided in a valve body, not shown, and the shutter 14 is then installed in this valve body.

The shutter 14 is connected to the valve body by means of a rod 22 making it possible to adjust its position relative to the seat 12.

The seat 12 and the shutter 14 are made of a metallic material, for example steel.

Thus, the annular contact zone 24 which extends between the shutter 14 and the seat 12 enables the upstream side of a duct 26 to be sealed off from its downstream 28.

The seal depends on the pressure of the shutter 14 against the annular receiving surface 16, but also on the state of the surfaces in contact largely conditioned by the machining of the surfaces.

Whatever the machining quality of these surfaces, they remain rough respectively.

And as illustrated in Figure 2, where there is a detail of the contact 25 between the shutter 14 and the annular receiving surface 16 of the seat 12, interstitial spaces 30, more or less connected to each other, remain between the surfaces. in contact 16, 24, regardless of the care taken during machining, and which causes the risk of leakage.

The total volume of these interstitial spaces constitutes the "opening field" h, and the sealing losses are functions of h3.

The shutter 14 and the seat 12 on which it rests are found in FIG. 1B in top view.

The opening 18 being shown in broken lines.

As will be explained below in more detail, we will focus on the angular position of the shutter 14 relative to the seat 12 in order to reduce the volume of the interstitial spaces to its minimum to obtain the best possible seal. between upstream 26 and downstream 28.

Reference is made on the one hand to Figure 4 showing a flowchart 5 showing the steps of the manufacturing method according to the invention, and on the other hand to Figures 5 to 7 showing the elements of a set of seals suitable for checking the flow rate of water flows.

Also, the elements functionally identical to those shown in Figure 1, will present in these Figures 5 to 7 the same references assigned a prime sign: "'Thus, according to a first step 32 is provided a hollow valve body 34 such as shown in Figure 5 and including a seat 12 ', as well as a shutter 14' as shown in Figure 6.

In Figure 5, the seat 12 'has an annular receiving surface 16' surrounding a passage opening 18 '.

Also, the valve body 34 has, upstream 26 'an inlet 36 and downstream 28' an outlet 38.

In addition, the valve body 34 has an upper mounting opening 40.

The shutter 14 'has a shutter surface 20' and it is surmounted by a control rod 22 'provided with a drive member 44.

Then, according to a second step 46, a first radial mark 48 is carried on the seat 12 'at the periphery of the annular receiving surface 16' in the form of a groove for example.

Still according to this second step 46, a second radial mark 50 is worn on the edge of the shutter 14 '.

Then, in accordance with a third step 52, the topography of the annular reception surface 16 ′ and of the closure surface 20 ′ is recorded.

To do this, we first use a contact profilometer comprising a diamond tip equipped with a position sensor.

With regard to the annular receiving surface 16 ′, five first concentric circular profiles are recorded between the interior and the periphery of the receiving surface.

In this case, each profile consists of 3600 measurement points, or 10 measurement points per degree, identified by three coordinates, the radius, the angle with respect to a first initial radius, and the axial position.

The latter has a precision of the order of a micrometer.

The first initial radius of the start of the measurement is marked with respect to the first radial mark 48.

8 Ideally, the initial starting radius intersects the radial mark 48.

And advantageously, the initial starting radius of the five profiles intersects the first radial mark 48.

The five profiles are for example spaced from each other by the same distance along the radius of the annular receiving surface 16 '.

Thanks to these 3600 times five measurement points, a first virtual surface is calculated by interpolation having first peaks and first hollows representative of the state of the annular receiving surface 16 ′.

Still according to this third step 52, the topography of the closure surface 20 'is also recorded in the same way in its peripheral part capable of coming into contact with the annular receiving surface 16'.

In this way, thanks to the recording of five second concentric circular profiles, each of the profiles also consisting of 3600 measurement points, identified from a second initial radius of the closure surface 20 ′ 15 intersecting the second reference mark radial 50, there is also calculated by interpolation a second virtual surface having second peaks and second hollows representative of the surface condition.

In accordance with a fourth step 54, a first placing in contact, one against the other, of the two virtual surfaces, the first and the second, is simulated.

In addition, this first contact is simulated so that the virtual marks, corresponding to the first and second radial marks 48, 50, are aligned with one another.

Also, the first peaks engage more or less well in the second troughs, while the second peaks engage in the first troughs, defining a first free space 25 between the two virtual surfaces.

Reference is made to FIG. 3B showing in partial section along a fraction of an arc, two portions of virtual surface, 56 corresponding to the closure surface 20 'and 58 corresponding to the annular receiving surface 16', in which precisely the initial first and second rays are superimposed and where the first and second radial marks 48, 50 are aligned.

Also, the first peaks 60 respectively engage more or less partially in second hollows 62.

Also, we can then evaluate a first total volume of free space 64.

9 Still in this same fourth step 54, a second placing in contact offset with respect to the first by 1 ° is simulated.

Continuing with the spirit of FIG. 3B, reference will be made to FIG. 3A where the two virtual surfaces are offset with respect to each other by 1 °.

In this second contact simulation 5, a second volume of free space 66 is evaluated.

360 is thus simulated bringing into contact the two surfaces successively offset from one another by 1 °.

And for each of these 360 contacts, we estimate a volume of free space.

Of course, in certain circumstances, in particular when the diameters of the annular receiving surface fo 16 ′, are small, it is possible to reduce the number of measurement points and consequently to carry out the contacting by shifting the 2 surfaces d. 'a step of 2 ° for example.

In other circumstances, when the diameters are large, it is advantageous to reduce the pitch and bring it, for example, to 0.5 °.

As illustrated schematically in Figure 3C, one of these 360 brought into contact has one where free space 68 is minimal.

Also, in a fifth step 70, the relative angular position of the two radial marks 48, 50 corresponding to this position where the free space 68 is minimal is recorded.

20 Starting from this last relative angular position, where the free space between the two virtual surfaces is minimal, one adjusts, in a sixth step 72, and as illustrated in FIG. 7, the shutter 14 ′ to the inside the valve body 34, so that it is oriented angularly with respect to the annular receiving surface 16 ', in the relative angular position retained.

To do this, account is taken of the two radial marks 48, 50 carried respectively on the seat 12 'at the periphery of the annular receiving surface 16', and on the edge of the shutter 14 '.

The shutter 14 'is then kept locked in rotation by means not shown.

It is, for example, by means of an axial groove made in the shutter 14 'in which a rib of the body 34 engages, the position of which is adjustable.

Also the rod 22 'is engaged in a cap 74 which closes the upper mounting opening 40.

The manufacturing method described above relates to a single seal assembly.

However, when sealing assemblies are produced in series, which is the general case, it is desirable to dispense with recording the topography of the surfaces required to form the seal, for all the seats and shutters. from the Serie.

Also, in a series production, a sample is taken from the series, each element of the sample comprising a plug and a valve body having a seat and an annular receiving surface.

For each element of the sample, after the second step 46 where the two radial marks are taken, the seat and the shutter are machined by orienting the radial marks in the same direction in relation to them. screw machining tools.

Then, as indicated above, and in accordance with the third step 52, the topography of the annular receiving and sealing surfaces of each of the sample elements is recorded to establish the corresponding receiving and virtual sealing surfaces. .

Then, in accordance with the fourth step 54, the placing of the virtual reception and obturation surfaces into contact is simulated in order to evaluate the total volume of the free spaces between the two virtual surfaces and thus to determine the relative angular position of the radial marks in which this total volume of free space is minimal.

Insofar as the angular offsets between the two radial marks are very close for each of the elements of the sample, it is considered that the machining tools cause the same type of defect.

And therefore, for the series considered, the fourth, 54, and fifth 70 steps of the aforementioned method are dispensed with, and account is taken of the angular offset obtained with the elements of the sample.

Claims (10)

CLAIMS 1. Method of manufacturing a sealing assembly suitable for controlling the flow rate of fluid flows, comprising the following steps: a) on the one hand, a hollow body (34) is provided comprising a seat (12 ') having a surface rough annular receiving surface (16 ') surrounding an opening (18') and on the other hand, a shutter (14 ') having a rough shutter surface (20') adapted to come to rest against said annular receiving surface rough (16 '); and, - b) said shutter (14 ') is installed inside said hollow body (34) facing said seat (12'); characterized in that it further comprises between steps a) and b) the following substeps: a) a radial mark (48, 50) is worn on said seat (12 ') and on said shutter (14' ); - p) recording the topography of said annular reception surfaces (16 ') and closure (20') respectively with respect to said radial marks (48, 50) in order to be able to establish virtual reception and closure surfaces; - y) the contacting of said virtual receiving and obturation surfaces is simulated, and the total volume of free space between the two virtual surfaces is evaluated, in each of the 360 ° / p relative angular positions angularly offset from one of the others of pitch p, p> 0; - 5) the relative angular position of said radial marks is recorded in which the total volume of free space is minimal; and in that in step b) said shutter (14 ') is installed in said relative angular position of said radial marks (48, 50) recorded with respect to said seat (12'). 2. Manufacturing method according to claim 1, characterized in that between the sub-steps a) and p), said annular receiving surfaces (16 ') and sealing (20') are respectively machined. 3. Manufacturing method according to claim 2, characterized in that the radial marks (48, 50) of said seat (12 ') and 12 of said shutter (14') are respectively oriented in a given direction when said surfaces are machined. annular reception (16 ') and closure (20'). 4. Manufacturing method according to any one of claims 1 to 3, characterized in that in step p) a plurality of concentric circular profiles of said annular receiving surfaces (16 ') and sealing are respectively measured. (20 ') to be able to record their topography. 5. Manufacturing method according to any one of claims 1 to 3, characterized in that in step 13) a plurality of radial profiles of said annular receiving surfaces (16 ') and sealing 10 ( 20 ') to be able to record their topography. 6. Manufacturing method according to claim 4 or 5, characterized in that said profiles are measured by contact. 7. Manufacturing method according to claim 4 or 5, characterized in that said profiles are optically measured. 15 8. Manufacturing method according to any one of claims 1 to 7, characterized in that in step (3) said virtual reception and sealing surfaces are established by interpolation. 9. Manufacturing method according to any one of claims 1 to 8, characterized in that 0.5 <p <5. 20 10. Sealing assembly suitable for controlling the flow rate of fluid flows, characterized in that it is obtained by a manufacturing method according to any one of claims 1 to 9. 25