ITMI20071608A1 - "WORK PROCEDURE FOR THE REALIZATION OF THE PUMP PACK AND HYDRAULIC VOLUMETRIC MOTORS." - Google Patents

Description

DESCRIPTION

of the industrial invention entitled:

"Working procedure for the realization of the pack clearance in hydraulic rotary volumetric pumps and motors",

The present invention relates to a working process for making the pack clearance in hydraulic rotary volumetric pumps and motors.

These pumps and motors use rotary pumping hydraulic fluid transfer elements (pumps) or actuators (motors) and realize a flow by converting mechanical energy into fluid pressure energy (pumps) or vice versa (motors)

The hydraulic energy produced by the pumps is used to operate, for example, actuators governed by control systems, for the most varied uses.

For example, a pump constitutes the flow source of the circuit, while the pressure is created only with a resistance to overcome. For example, if the resistance is represented by a load on a piston, only enough pressure will be generated to drive the load.

The volumetric machine with fluid transfer elements consisting of "External Gears" is described below because it is more widespread, but the conclusions can also be extended to those with "Internal Gears", "Gerotor", "Orbitals", "Lobi" and to "Palette".

An external gear pump is commonly made up of

• a fluid inlet opening (suction), to which the supply line from the tank is connected

• an outlet opening (delivery) which is placed in communication with the pressure line

• a pumping chamber which is the volume in which the fluid is isolated when passing from the suction to the delivery (between the compartments of the teeth, body and side elements without connections with suction or delivery)

• a body in ferrous material (eg cast iron) or non-ferrous material (eg aluminum) • a front cover (eg aluminum or cast iron)

• bushings (eg aluminum or bronze)

• a rear cover (eg aluminum or cast iron)

• drive and driven gears (eg steel)

• body-lid gaskets (eg rubber or special plastic materials). A motor has the main purpose of providing mechanical energy to drive a load, converting the pressure energy of the fluid generated by the pump. An external gear motor has a similar structure to the pump and differs in the internal drainage since it is built to work in both directions of rotation; on the reverse of the pump, the suction port receives fluid from the pressurized line and the delivery port is at lower pressure and is connected to the tank.

The bushes are also called spectacles due to the typical eight shape and can also be divided in half into two semi-glasses.

The main function is the mechanical seal of liquids under pressure on the surface in contact with the side of the gear or on the opposite surface in contact with the cover or with the blind bottom of the pump body, for which we will call them "Side sealing elements" with generic reference to these elements for all rotary volumetric hydraulic machines.

The bushings can also be supporting elements of the gear shanks and have a hole that becomes the seat of a plain bearing, to reduce mechanical friction and improve performance and durability.

More frequently for pumps / motors with cast iron body, the seat of the sliding bearings is obtained on the closing covers or on the blind bottom of the pump body and in this case the bushings are thinner as they do not have the function of supporting the gear shafts. .

The success of external gear pumps and motors is due to a set of characteristics such as the remarkable lightness, the simple mechanics, Γ adaptability in small compartments to any position, tolerability to viscosity variations, Γ excellent suction, the wide range of flow rates available and certainly not least, the cost that makes these hydraulic machines among the cheapest available on the market.

The strong demand for these hydraulic generators has spurred manufacturers to continuously search for high-quality products with special materials, accurate heat treatments, minimum coupling tolerances and super-finishing of surfaces with the aim of reaching ever higher pressures (e.g. up to 300 bar), reduce noise, and improve efficiency.

With this in mind, the optimal realization of a feature called "pack axial play" or "pack play" described below has become increasingly important.

With "pack" we refer to the components inserted inside the body coupled together and the relative overall height and with "axial play" of the pack we mean the difference between this height of the "pack" and that of the body that contains it.

In practice, this measure represents the space available for the package components to float inside the body.

The smaller the play of the components inside the body, the lower the losses will be, reducing the space for the leaks themselves.

Hydraulic machines can have fixed or balanced axial play.

In the case of "fixed axial play", the bushings, if present, do not have a balancing function and the design value of the play is minimal and reduced to a few hundredths of a millimeter, which cannot be further reduced without the risk of seizures, both due to the machining tolerances of the components and because the deformations induced on the components by pressure must in any case be allowed.

In the case of "axial play of the compensated or balanced pack" the delivery pressure is sent, through internal channels, behind the bushings and acts on surfaces suitably delimited by the gaskets (so-called balancing) housed in seats obtained on the bushings themselves or on the covers.

This system creates forces that bring the bushings closer to the sides of the gear wheels, eliminating the play and therefore the leakage in the coupling between the bushing-gear side surfaces, without inhibiting the presence of a lubricant film which increases wear resistance. and therefore the duration.

In this case, the axial play can assume values a little larger than the fixed play, for example around the tenth of a millimeter, to avoid that the thrust on the gasket, "compresses" the gear wheels with excessive friction, and causes problems for the goodwill.

In recent years, performance has continued to exacerbate both pumps and hydraulic motors, with increasingly higher pressures and sudden changes in loads.

Hence the need to increasingly contain the "axial clearance of the pack" within narrow tolerance values (a few hundredths of a millimeter) and close to the minimum necessary for the correct operation of the gasket with the balancing counter pressure.

Most of the most common industrial applications can refer to two schemes: with perforated body (through) and with blind body. In both cases, the G dimension of the "axial clearance of the pack" is determined by the difference between the measurement of the height of the body and the sum of the thicknesses of the internal elements (bushings and gears).

As previously defined, the height of the perforated body or depth of the blind body must be greater than the sum of the components mounted inside the body by a clearance value G and the pump performance will be the better the closer this clearance is to theoretical value established, with a tolerance as limited as possible.

The components of the "Pack" (body, gears, bushings) are today made with procedures (eg machining centers and grinding for the gear shoulders) which induce a variability on the share of the "Play", which is not tolerable for a significant percentage of the high performance applications required today.

Even resorting to final "super-finishes" on the individual components, such as grinding / lapping of opposite surfaces on the body and on the bushings, in addition to higher costs, a quality that is not yet optimal in relation to the reciprocal geometries of the components (perpendicularity and parallelisms) would be obtained which are corrected by grinding / lapping.

The object of the present invention is to provide a working process for obtaining hydraulic pumps and motors capable of containing more than the known processes the "pack axial clearance" within narrow tolerance values close to the minimum necessary for operation.

In accordance with the invention, this object is achieved with a working procedure for the realization of the pack clearance in hydraulic rotary volumetric machines comprising means for transferring hydraulic fluid from an inlet to an outlet, housed between two lateral sealing elements. in a body closed by at least one lid, characterized in that it comprises the steps of:

• semi-finishing machining of the lateral sealing elements and of the body, with allowance on the height of the body and of the lateral sealing elements,

• creation of a service thickness with a height corresponding at least to the value of the project pack clearance to be created,

• realization of a pre-assembled unit comprising the body, the thickness and the two lateral sealing elements.

• finishing and / or super-finishing machining of the external surfaces of the pre-assembled to obtain the project pack clearance with minimum tolerance

• functional assembly using hydraulic fluid transfer means and elimination of the service thickness.

Advantageously, the method described above can provide a preassembled with a service thickness with a height corresponding to that of the means for transferring the hydraulic fluid plus the value of the design pack clearance to be made. In this case, the functional assembly will provide for the replacement of the service thickness with the fluid transfer means.

Still advantageously, the method can provide a service thickness of height equal to the value of the design pack clearance to be made, since the means for transferring the fluid are present in the press-assembly. The functional assembly will simply consist in the removal of the service thickness.

These and other characteristics of the present invention will be made clearer by the following detailed description of an example of its practical embodiment illustrated, by way of non-limiting purposes, in the attached drawings, in which:

Figure 1 shows an exploded perspective view of a gear pump with a hollow body according to the present invention;

Figure 2 shows a cross-sectional view of the assembled pump in operation;

Figure 3 shows a schematic vertical sectional view of the preassembled pump;

Figure 4 shows a schematic sectional view similar to that of Figure 3 of the assembled pump;

Figure 5 shows a schematic vertical sectional view of a pre-assembled blind-body pump;

figure 6 shows a schematic sectional view similar to that of figure 5 of the pump with assembled blind body;

figure 7 shows a front view of a gerotor according to the present invention;

figure 8 shows a front view of a first lateral sealing disk of the gerotor;

figure 9 shows a front view of a second lateral sealing disk of the gerotor.

A hydraulic pump with external gears 1 comprises a body 2, in which bushings or glasses 3-4 are housed, which support gears 5 (driving shaft 6 and driven shaft 7) (Figure 1).

Covers 8 close the pump by means of fixing screws 9.

The pump 1 further comprises a fluid inlet or suction mouth 10 and a fluid outlet or delivery mouth 11 (Figure 2).

Gaskets 12 with seats obtained on the bodies, on the bushings or in correspondence on the covers (the oval ones being external to the bushings) complete the pump 1 (those on the so-called balancing bushings are equipped or not with anti-extruder housed in a profiling in the shape of the gaskets themselves)

The working process according to the present invention, described below, uses one of the oldest and most known grinding / lapping processes, but is characterized by the process of working the pre-assembled parts in relation to the axial clearance characteristic to be obtained. package.

This grinding / lapping process takes place for example by means of parallel planes and with the addition of abrasive material that removes material from the piece (capping) or with real parallel flat wheels that constitute the removal tool (grinding), but with similar results for the purposes of the procedure described.

Grinding / lapping allows to obtain particularly precise surfaces with regard to planarity, roughness and parallelism between them, using for example so-called parallel plane machines or one or two single plane grinding / lapping machines with sequential finishing of the two planes, or, machines with passage of the pieces under a single wheel suitably shaped and inclined for the realization of a flat surface parallel to the opposite one, or machines with passage of the pieces under two opposing and independent wheels suitably shaped and inclined for the creation of flat and parallel surfaces or similar grinding machines that have developed over time.

It must be considered that grinding / lapping does not correct the geometries of the machined surfaces in relation to the unmachined surfaces, but leaves them basically unchanged (the perpendicularity between the machined surfaces and the axes of the internal surfaces of the body 2 and the external surfaces of the bushings 3-4 will remain so even after processing).

It is proposed to leave an appropriate stock allowance (e.g. of about 0.2 mm) on the height of the body 2 and of the bushings 3-4 and to add a final grinding / lapping machining of the pre-assembled components (pre-assembled 13),

For both cases of perforated or blind body 2 (figures 3-4 and 5-6 respectively), a thickness 14 is made, the height of which will have a value corresponding to that of the toothed band of the gears 5 (which it replaces in this phase, see figures 3 and 5) that is calibrated on the average value of the tolerance allowed by the machining process of the gears 5, plus the value of the axial clearance of the design package to be made.

The thickness 14 will be obtained with particular precision on the height and parallelism of the opposite faces, and can be in a single piece, or two half-thicknesses obtained from a bar, etc.

This thickness 14, used as a tool in the grinding / lapping process, will be inserted with the bushings 3-4 inside the body 2.

The external surfaces of the body 2 and of the bushings 3-4, pre-assembled, will therefore be ground / lapped.

The procedure is based on the observation that the axial play of the pack made in this way, being a difference in heights, will no longer change from the moment in which the grinding / lapping process makes the heights of the body 2 and of the pack consisting of the bushings 3-4 plus thickness 14 equal to each other.

In fact, if G is the "pack clearance", X and Z are the heights of the bushings 3-4, and Y is the height of the thickness 14:

G = W- (X Y Z) where the height W of the body 2 is the minuend and the height (X Y Z) of the package is the subtract.

If the minuend and the subtract of the same entity vary, the result of the subtraction does not change.

It should be noted that the feasibility of this final grinding / lapping operation of the pre-assembled components is much simplified compared to the same operation performed on the individual components, as it is not necessary to respect a narrow tolerance on the overall height of the body 2 and of the package, while it is necessary to respect it by working on the individual components.

It should be noted that due to the aforementioned limit of the grinding / lapping process the only important constraint that remains unchanged in the comparison between the proposed procedure and the current ones is to maintain particular care for the 3-4 bushings on the geometry of perpendicularity between the gear side and the external contour surface of the bushings themselves 3-4, which must coincide with the corresponding geometries on the gears 5 (which remain unchanged since they are not taken up with the proposed processing) in order to guarantee sealing against oil leaks from the area at high pressure to the lowest pressure zone.

The particularly restrictive constraints, present with the processes most used in industry today, are considerably reduced, as well as on the height of the components, also on the geometries of the body 2 (roughness, flatness, plane parallelism and perpendicularity with the drilling axis ) and on the similar geometries of the 3-4 glasses on the gasket side only.

Some details of the application of the procedure will be described below in relation to the constructive choices, recurrent today in industrial applications, that is to realize the seat of the balancing gasket 12 on the covers 8 (optimal choice for the above procedure) and also vice versa to realize it on the bushings. 3-4 (less appropriate choice).

a) Balancing gasket 12 on the covers. If the body 2 is drilled (figures 3-4), for example, the bushings 3-4 are inserted inside the body 2 as in the functional assembly, i.e. with the gasket sides facing outwards and with the calibrated thickness 14 in the center and performed a super-finishing process with grinding / lapping, of the external sides of the preassembled.

If the body 2 is blind (figures 5-6) the procedure is the same except for the bushing 4, positioned on the blind bottom which, not affected by superfinishing, which will have the balancing gasket seat and accuracies similar to those obtainable with the current procedures as regards the geometries of parallelism and perpendicularity of the surfaces, while allowing less precision on the height share.

b) Gasket 12 on bushings 3-4. The application of the proposed procedure may also take place with the construction variant which provides for the seat of the balancing gasket on the bushings 3-4, although this is the least convenient solution. In fact, the presence of the gasket seat on these sealing elements constrains the machining, if performed on this side, to the depth of the groove itself and to the geometries of the previous precise and critical machining as in current processes. However, it will be possible to carry out the procedure in this way, leaving small allowances to be removed by grinding / lapping and thus minimizing the errors induced on the depth of the gasket groove. If the superfinishing with grinding / lapping is performed on the opposite side (gear side) with inverted bushings, the advantage of freeing itself from the precision on the height of the body components 2 and also of the bushings 3-4 will be maintained but the parallel geometries must be kept precise and perpendicularity of both, which cannot be corrected by grinding / lapping and determining as a result of the processing which will maintain a perpendicularity between the gear side and the contour on the bushings 3-4 only in relation to the pre-existing one on the body 2 between the planes and the central hole (pack seat). In the case of perforated body 2, the bushings 3-4 are inserted inside the body 2, inverted with respect to the functional assembly, that is, with the gear sides facing outwards and with the calibrated thickness 14 in the center. A superfinishing process will be performed, for example with grinding / lapping of both planes simultaneously or in succession. In the case of blind body 2, bushings 3-4 are inserted inside body 2, of which the external one will have the gear side facing outwards and a grinding / lapping process will be performed on one plane only.

For both reference cases, the subsequent functional assembly must take place by replacing the thickness with the definitive gears, and correctly positioning the bushings with the gear side inside and the gasket side outside. In the case of the perforated body 2, if the gear side of the bushings has been machined, it is also possible to exchange the position of the bushings between them in order to maintain the same geometric error in the coupling with the body 2 on the perpendicularity between the planes and the axis of the location of the package. In this case it must be remembered that this error must in any case be very small, since the reference geometry of the gears 5 (ground on the outside and on the sides of the toothing) is binding, compared to the drilling of the body 2 and consequently the error must be small. also on the 3-4 bushings between the gear side and the contour.

Alternatively, it is also possible to position the shim 14 towards the outside of the body, for example in the case of a perforated body 2 and the use of grinding machines on a single plane, so that the magnetic countertop underneath a belt for the advancement of the pieces, can block the thickness 14 (metal) and the belt consequently drags the pre-assembled in advancement under the grinding wheel.

The machining of the remaining surface of the body and of the relative bushing will take place by repositioning the thickness 14 towards the external side previously machined and grinding the opposite side as above The realization of the G dimension of the pack clearance will be precise unless the difference between the calibrated thickness 14 realized on the average value of the adjustment dimension of the gear 5 and the real dimension of the gear itself 5, so for example if this dimension varies up to 0.01 mm with respect to the nominal dimension, then the maximum error will be half or 0.005 mm .

The value of this tolerance will be totally acceptable and compatible with the design of the pack game and will allow to avoid malfunctions in the previously mentioned high performance conditions.

In particular, the problems of poor performance or high starting torque at the start of pumps and motors, which today are detected by the manufacturing companies, on the test benches, or by the final customers themselves, will be eliminated.

In this way it will be possible to further push the performance of the products, directly dependent on the accuracy of the axial play of the pack.

The production costs can also be reduced by a significantly higher amount than that introduced with the additional processing proposed on the pre-assembled, simplifying the previous processing, where a particularly high precision on the individual components is no longer required:

• Body 2: lower precision, on the height, on the geometries and on the roughness of the flat surfaces of the cover coupling.

• Bushings 3-4: lower precision, on the height, on the geometry and on the roughness of the flat surface on the external side of the pump (towards the covers). The lower accuracies will allow greater reliability of the mechanical machining of the components and therefore special machines can be made for the production of bodies and bushings, with high productivity and therefore lower costs.

As an example, just think that the cutting phase of the extruded aluminum profiles, from which the semi-finished product is obtained for the subsequent processing of the bodies, can be carried out with a cutting machine with sufficient precision on the flat faces of coupling with the covers, without having to undergo further processing, up to the final stage of processing the pre-assembled with the proposed procedure.

With the application of the proposed procedure, albeit with great approximation, a reduction of a few percentage points (2-3%) of internal and external waste is conceivable. The economic value can be referred to the full cost of the product for each scrap eliminated, (over 50 euros / each for the poorest products, with a legitimate approximation having to include the total costs of non-quality) and makes evident the interest that this procedure could be found in industrial applications on the reference market.

The application of the procedure can be identified with simple checks carried out with a three-dimensional machine (CMM Computer Measuring Machine), measuring the degree of accuracy of the pack clearance itself and / or the parallelism of the body and bushing planes and / or the perpendicularity between the surfaces of the body and the internal drilling of the pack seat, for example in the following ways:

The body 2, with the elements of the pack inserted, will be placed on a plane of control equipment, which allows the passage of any shafts of the fluid transmission elements. On the body 2, the opposite plane will be detected in many points and in the same way the plane of the bushing will be detected and the distance between the planes will be calculated by the CMM (axial clearance of the pack). The measurement will be repeated on several similar products under examination and if the proposed procedure has been applied, the result will be uniformity of the measurements of different products with variations of a few microns, vice versa if the components have been processed separately, centesimal and above all variable differences will result. among the different products controlled.

With the same previous positioning on the control equipment, it is also possible to measure the parallelism of the body 2 planes and 3-4 bushes, the plane of the body 2 will be detected in many points and in the same way the plane of the 3-4 bushing. If the two surfaces have been ground / lapped at the same time because they are pre-assembled as in the proposed method, the result will be a negligible parallelism error and with the same geometric orientation and with differences of a few microns between different measured products. Conversely, if the components have been processed separately, the error will be not negligible and above all variable with centesimal differences on the different products measured.

It is also possible to proceed to the further measurement check of the perpendicularity between the planes of the body 2 and the internal drilling. It will be measured with CMM, simply probing a sufficient number of points to locate the drilling plane and cylinder. If this perpendicularity, even if it is imprecise, will have an error coinciding in value, direction and orientation of the geometry, with that between the plane and the contour of the bushings, then it is highly probable that the components have been machined with the proposed procedure and this would be confirmed from the repetition of this condition on different components.

Below is also a summary of an application of the procedure to the "Gerotor" type 20 rotary volumetric pump / motor with internal gears, in order to exemplify the possibility of extending the procedure to all hydraulic rotary volumetric machines, where they exist: a body that contains fluid transfer elements and lateral sealing elements, which when coupled constitute the pack and that the clearance of the pack inside the body is fixed or is balanced or compensated to achieve the seal between these internal elements, using the pressure of delivery, acting on the lateral sealing elements, using balancing gaskets not shown here.

Fig. 7 shows a front section of this pump, with a body 15, a male central gear or pinion 17 with external teeth and a peripheral female or crown 16 with internal teeth, which have the same height (thickness) and which we will call generically "fluid transfer elements"

The cylindrical outer shape crown 16 is inserted in a similar seat obtained in the body 15 and is free to rotate on itself driven by the rotation of the pinion 17, made integral with the transmission shaft.

The centers of rotation of the pinion 17 and of the crown 16 are fixed and do not coincide, furthermore the pinion 17 has one tooth less than the crown, so that in the coupling between the teeth there is a complete contact area on the whole profile, without empty space that can contain the fluid, to an area where the free volume grows creating a depression used for the suction of the fluid, to an area where the volume decreases creating a compression towards the delivery duct.

Two plates or discs 18-19 lateral to the gears (Figures 8-9), constitute the elements that perform the function of distributing the fluid towards the suction and delivery ducts, obtained in a closing cover, or in the blind bottom of the body and also the function of containing lateral losses and, if present, axial balancing, by means of suitable gaskets that limit the pressure area in the external area (opposite to the gears) from the delivery area through suitable drainages, exactly as already seen for the bushings in the external gear pump.

A common construction form on internal gears is with a transmission shaft keyed to the pinion (not shown in the drawings shown) This configuration is sometimes also used in external gear machines for both the driving and driven elements and allows for the application of a variant to the procedure described above. The preassembled assembly will be formed by inserting between the sealing elements 3 and 4 the fluid transmission elements (gears) 5, without the relative shafts, and a thickness 14 having a height corresponding to the pack clearance to be made. In this case the preassembled (13) will be like that of Figures 4 and 6 with a further infinitesimal thickness (14) not appreciable in a graphic representation with correct proportions. The subsequent functional assembly phases simply consist in removing the service shim and inserting the fluid transmission elements complete with shafts. This variant can be applied as an alternative to the procedure described above for external gear machines, where the constructive form of the gears provides for subsequent keying with the shafts.

In this way, the error corresponding to the difference between thickness 14 and actual height of the fluid transmission elements is also eliminated.

Claims (23)

CLAIMS 1. Working process for making the pack clearance in hydraulic rotary volumetric machines (1, 20) comprising means (5, 16-17) for transferring hydraulic fluid from an inlet (10) to an outlet (11 ) housed between two lateral sealing elements (3-4, 18-19) in a body (2, 15) closed by at least one cover (8), characterized by understanding the phases of: semi-finishing machining of the lateral sealing elements (3-4, 18-19) and of the body (2, 15) with allowance on the height dimensions of the body (2, 15) and of the lateral sealing elements (3-4, 18 -19), creation of a service thickness (14) with a height corresponding at least to the value of the project pack clearance to be made, realization of a preassembled (13) comprising the body (2, 15), the shim (14) and the two lateral sealing elements (3-4, 18-19), finishing and / or super-finishing machining of the external surfaces of the pre-assembled assembly (13) to obtain the design pack clearance with minimum tolerance, functional assembly using the means (5, 16-17) for transferring hydraulic fluid and eliminating the thickness (14). 2. Process according to claim 1, characterized in that said thickness (14) has a height corresponding to that of the value of the design pack clearance to be made, the functional assembly providing for the replacement of the thickness (14) with the means (5, 16-17) of hydraulic fluid transfer. 3. Process according to claim 1, characterized in that the pre-assembled assembly (13) comprises the means (5, 16-17) for transferring the hydraulic fluid. 3. Process according to any one of the preceding claims, characterized in that said hydraulic fluid transfer means comprise gears (5, 16-17). 4. Process according to claim 3, characterized in that said gears (5) comprise a driving shaft (6) and a driven shaft (7) with external meshing gear wheels 5. Process according to claim 3, characterized in that said gears comprise a crown (16) and a pinion (17) with internal meshing toothed wheels. 6. Process according to claim 3, characterized in that said gears comprise a driving shaft (6) and a driven shaft (7) separable from the meshing toothed wheels. 7. Process according to any one of the preceding claims, characterized in that said lateral sealing elements have the shape of glasses (3-4), consisting of a single piece or two half-bushes, or of plates / discs (18-19) 8. Process according to any one of the preceding claims, characterized in that said lateral sealing elements also have the function of supporting the fluid transfer means. 9. Process according to any one of the preceding claims, characterized in that said lateral sealing elements also have the function of balancing and compensating for the pressure. 10. Process according to any one of the preceding claims, characterized in that said semi-finishing, finishing or super-finishing process comprises the grinding process. 11. Process according to any one of the preceding claims, characterized in that said semi-finishing, finishing or super-finishing process comprises the capping process. Method according to any one of claims 10-11, characterized in that the grinding or lapping process takes place by means of parallel plane machines. 13. Process according to any one of claims 10-11, characterized in that the grinding or lapping process takes place by means of one or two single-plane machines with subsequent finishing of the two surfaces. 14. Process according to any one of claims 10-11, characterized in that the grinding process takes place by means of machines with passage of the pieces under a single wheel suitably shaped and inclined for the realization of a flat surface parallel to the opposite one. 15. Process according to claim 13-14 characterized by the fact that the thickness (14) is positioned outside the perforated body and the opposite side is ground. 16. Process according to any one of claims 10-11, characterized in that the grinding process takes place by means of machines with passage of the pieces under two opposing and independent grinding wheels suitably shaped and inclined for the realization of flat and parallel surfaces 17. Process according to any one of the preceding claims, characterized in that it is suitable for hydraulic pumps and motors with balancing gaskets (12) housed in seats obtained on the covers (8). 18. Process according to any one of the preceding claims, characterized in that it is suitable for hydraulic pumps and motors with balancing gaskets (12) housed in seats obtained on the lateral sealing elements (3-4, 18-19). 19. Process according to any of the preceding claims, characterized in that it includes the inversion of the sealing elements (3-4, 18-19) during the functional assembly phase. Method according to any one of the preceding claims, characterized in that it is suitable for hydraulic pumps and motors with a perforated body (2, 15). Method according to any one of claims 1-19, characterized in that it is suitable for hydraulic pumps and motors with body (2, 15) with blind hole. 22. Process according to any one of the preceding claims, characterized in that the body (2, 15) and the lateral sealing elements (3-4, 18-19) are obtained with traditional machine tools, flexible machining centers or special machines dedicated to single processes to reduce the overall cycle time. 23. Process according to claim 22, characterized in that the semi-finishing processing of the height of the body is obtained directly in the cutting step of the extruded profile.