IT202100002114A1 - ACTUATOR DEVICE - Google Patents

Description

ACTUATOR DEVICE

DESCRIPTION

The present invention relates to an actuator device.

The invention finds application, particularly but not exclusively, in the industrial sector of machine tools such as presses, for example for deformation or shearing operations, in molds and mold components (for example blank holders), or in general in machines which require the damping of dynamic phenomena (vibrations) or the application of dissipative forces.

The device ? of the double effect type and ? adapted to work both as a semi-active and active type actuator. For active actuator here we mean a device that allows to exert a force on the system to which ? connected thanks to the injection of external energy applied in strategic points of it, in the form of force independent of the system that generates the movement of the device. By semi-active actuator here we mean a device capable of applying a force on the system to which it? connected without the input of external energy, such that the force ? generated as a reaction to the behavior of the system, but pu? be adjusted during operation when necessary.

By "double-acting devices" in the field we mean cylinders which have two chambers in which the pressurized fluid can act alternately, so as to exploit its thrust both during the working stroke of the rod and during the repositioning stroke.

The use of damping devices inside presses is known, for example as an aid to molds or mold components. During a drawing operation, since the area on which the blank holder acts (in charge of avoiding the formation of wrinkles on the sheet) decreases with the progressive sliding of the sheet inside the mold and, in general, in a different way during stamping stroke, ? required that the force follows a particular law as a function of the molding stroke, which is typically decreasing.

Furthermore, during a molding process eccentric loads can be generated which lead to an overload of the guides and to an alignment error of the molds to the detriment of the precision of the molded component.

In a shearing process, when the fracture appears, there is an instantaneous release of energy stored in the press structure during the process, which leads to noise, vibrations and consequent possible damage to mechanical or hydraulic components, forcing a preventive oversizing of the molds or of the machines themselves.

In the case of a press, the stripper ring ? designed to transmit a force to the sheet in contrast to the movement of the upper half-die of the press. The blankholder? supported by candles which are in turn supported by a blank holder cushion. In the building widespread of the presses, the lower table, with the lower half-mould,? fixed, while a slide pushes the blank holder. The cushion, also known in the sector as a "box", is mounted on actuators, known in the industry as blank holder pistons, which act against the downward movement of the slide.

To date, for the purpose described above, pneumatic cylinders connected to air tanks are often used. During the stroke of the slide, the air is compressed, guaranteeing the force required for the blank holder (passive phase) and the subsequent ascent (active phase). Force adjustment? limited to setting the initial pressure.

These have a number of non-negligible drawbacks, including the fact that:

- the reaction force not ? constant but increases during the molding stroke, therefore in the opposite way to what is generally required;

- not being able to control the ascent phase, in the event of seizure or damage, the presence of residual pressure can? lead to uncontrolled movements of the blank holder at the time of solving the problem and a possible release of the pressure would require times that are not compatible with those necessary for the prevention of accidents;

- large dimensions;

- generation of harmful inverse loads acting on the mechanical parts, in mechanical presses, which require a braking action by the motor of the machine, with consequent energy dissipation and thermal overload of the motor itself,

- to check the return movement of the blank holder ? request, in hydraulic presses, a braking action to the stem to limit the speed? rising, with consequent energy dissipation and increase in the working cycle time of the press.

Other stripper cylinders are hydraulically operated. In this case, compared to the previous one, are more overall dimensions? contents and adequate control technology (sensors, valves and control software/hardware, etc.) which allows the pressure in the cylinders to be modulated. However, even these are not free from drawbacks, in particular due to the relatively high costs and the generation of heat to be disposed of (due to the lamination of the fluid).

The use of nitrogen-charged cylinders (also known in the sector as "springs") is also known, the overall dimensions of which ? limited, especially when the tank ? obtained in the cylinder itself, but the limits of the air stripper cylinders remain.

Other solutions are represented by:

- spring actuators, which can only be used for small strokes and low-level forces? and which are not able to absorb the vibrations that can be generated during the process;

- antishock devices (for blanking), cio? oil actuators with dissipative valve to dampen vibrations, but with limited strokes for the incompressibility? of the fluid.

A possible solution? represented by semi-active actuators using magnetorheological fluid (typically mineral oil with metal powder dispersion), in which the fluid passes between two chambers through calibrated passages in the piston head. Does the fluid change its viscosity? if subjected to a magnetic field, to generate the required resistance, which can? be induced by the passage of current in cables which pass through the rod, which, depending on the applications, constitutes the mobile part or the fixed part of the actuator. These devices find application in the automotive and aeronautical sectors, as vibration dampers and shock absorbers, where high performance is required, for speed? typical reaction of magnetorheological fluids to the variation of the current and therefore to the magnetic field. To date this solution is not ? adopted in machines, such as tools, due to limitations due to the dimensions of the volume compensation systems, which require space and can show losses at the connections, due to the limited number of cables that can be inserted in the stem and due to technical complications due to the passage of cables in parts in movement. Furthermore, to obtain levels of force suitable for use in machine tools and the like, it would be necessary to increase the amount of magnetized fluid and therefore the length of the stem, which must be occupied with electric cables.

The task of this invention? that of realizing an actuator device, which is capable of improving the prior art in one or more? of the above aspects.

Within the scope of this aim, an object of the invention is that of realizing an actuator device of compact dimensions, whose thrust force can be rapidly, easily and effectively modulated, thus? as well as the speed? and the rising position of the stem.

Another purpose of the invention? that of realizing an actuator device, able to dampen vibrations of the machine parts to which ? applied and/or to exert reaction forces in contrast to the movement of the machine parts to which ? applied, for example to contrast rotations of parts of molding machines in the presence of eccentric loads or to control their stroke.

Another purpose of the invention ? that of realizing an actuator device whose thrust force can be modulated instant by instant.

Another purpose of the invention? that of proposing a device with which it is possible to avoid dangerous and harmful situations of instantaneous release of energy stored in the structures in which ? applied.

Another purpose of the invention ? that of realizing a device with reduced overall dimensions compared to other similar devices known to date.

Another purpose of the invention? to limit energy dissipation in the machines in which ? applied and increases in the machining cycle time of the machines.

Furthermore, the object of the present invention is to overcome the drawbacks of the prior art in an alternative way to any existing solutions.

Not the last purpose of the invention ? that of realizing a device that is highly reliable, relatively easy to manufacture and at competitive costs.

This task, as well as these and other aims which will become apparent hereinafter are achieved by an actuator device, of the type using magnetorheological fluid, characterized in that it comprises at least the combination of:

- a shirt,

- a tubular sleeve, internal to said sleeve and concentric with it, on the outer wall of said sleeve having electrical windings, said sleeve being closed on one side by a bottom and on the opposite side by a head with holes for the passage of - a first hollow stem capable of protruding from said head by translating up

- a second hollow stem extending from said bottom inside said bush, said first and second hollow stem cooperating with each other in a telescopic manner,

- an annular element integral with said first hollow stem, translating with it inside said bush,

- a first chamber, which develops around a portion of said second hollow stem, between said bottom and said annular element and suitable for containing said magnetorheological fluid,

- a second chamber, which develops around a portion of said first hollow stem and which? in fluid connection with said first chamber by means of a gap between said sleeve and said jacket,

- a third volume compensation chamber.

Further characteristics and advantages of the invention will become clearer from the description of two preferred, but not exclusive, embodiments of the actuator device according to the invention, illustrated, for indicative and non-limiting purposes, in the attached drawings, in which:

figure 1 shows a longitudinal section of the device according to the invention, in its first embodiment, in a working position;

figure 2 illustrates the device according to the invention as in figure 1 and in another configuration;

figure 3 shows another longitudinal section of the device according to the invention, still in its first embodiment and in a further arrangement;

- figure 4 shows an elevation of the bush of the device according to the invention;

figure 5 shows a longitudinal section of the device according to the invention, in its second embodiment, in a working position;

figure 6 illustrates the device according to the invention as in figure 5 and in another configuration;

- figure 7 illustrates another longitudinal section of the device according to the invention, still in the second embodiment and in the arrangement shown in figure 5.

With reference to figures 1 to 4, the actuator device according to the invention ? indicated with 10 in its first embodiment, described below, and ? of the type using magnetorheological fluid.

It comprises a jacket 11 of cylindrical shape and a bush 12, tubular, inside the jacket 11 and concentric with it.

One of the peculiarities of the device 10, according to the invention, lies in the fact that on the outer wall of the bush 12 there are electrical windings 13, for example electrical tapes or cables.

The jacket 11 has a substantially cup-shaped body, being closed on one side by a bottom 14 which is made as a single body with a tubular portion 15. On the opposite side, the jacket 11 is? closed by a head 16 that ? drilled for the passage of a first hollow stem 17.

Compass 12? provided with first spacers 38, substantially the feet with which it rests on the bottom 14 of the jacket 11 and, on the opposite side, with second spacers 39 from the head 16.

The device 10, according to the invention , therefore comprises the combination of at least the elements listed below:

- shirt 11,

- compass 12,

- the first hollow stem 17, which ? adapted to protrude from the head 16 by translating, along a translation axis X, up

- a second hollow stem 18 extending from the bottom 14 inside the bush 12,

- an annular element 19 integral with the first hollow stem 17, translating with it inside the bush 12,

- a first chamber 20, which develops around a portion of the second hollow stem 18, between the bottom 14 and the annular element 19 and suitable for containing magnetorheological fluid,

- a second chamber 21, which extends around a portion of the first hollow stem 17 and which is in fluid connection with the first chamber 20 through a calibrated cavity 22 between the bush 12 and the jacket 11 (in particular between the lower edge of the bush 12, for a height equal to that of the first spacers 38, and the bottom 14 and between the external tubular wall of the same bush 12 and the internal tubular wall of the jacket 11),

- a third chamber 23 (visible in the configurations of figure 1 and figure 2) for volume compensation.

The first hollow stem 17 and the second hollow stem 18 cooperate with each other in a telescopic manner.

The cavity 22? passable by the magnetorheological fluid (in the passage from the first chamber 20 to the second chamber 21 and vice versa) here affected by the magnetic field generated by the passage of current in the electric windings 13. The intensity? of the electric current which runs through the electric windings 13 ? adjustable by means of an electric power supply, both in non-working or set-up phases, and during the working stroke of the first hollow rod 17.

The spacers 39, maintaining the distance between the head 16 and the upper edge of the tubular part of the bush 12, allow the passage of the magnetorheological fluid to and from the interspace 22 and prevent the translation of the same bush 12 along the axis X. Moreover they provide for the coaxial centering of the bush 12 with respect to the jacket 11.

The jacket 11 and the bush 12 are made of material permeable to magnetic fields, preferably low carbon steel, pure iron or other specific alloys for magnetic applications, thus allowing the passage and closure of the lines of force of the magnetic field which is generated around the windings crossed by current, investing the fluid in the interspace 22. The head 16 can? be made of non-magnetic material and, in a different construction variant, the bottom 14 of the shirt could also be made of non-magnetic material.

Another important peculiarity? lies in the fact that the third chamber 23 develops around a portion of the first hollow stem 17, separated transversally from the second chamber 21 by means of a separator element 24.

The annular element 19 transversely separates the first chamber 20 from the third chamber 23.

The separator element 24 ? ring-shaped and installed at least around a portion of the first hollow stem 17.

The same separator element 24 ? able to translate along the same translation axis X of the first hollow stem 17 inside the bush 12. A stop ring 40 (for example a seeger) is suitably present around the first hollow stem 17 (in a special groove), between the head 16 and the separator element 24, which prevents it from closing on the head 16 when the stem 17 moves to TDC.

In this first embodiment, the second chamber 21 is comprised between the head 16 and the separator element 24 and the third chamber 23, which ? a compensation chamber of the internal volume, which undergoes a variation during the translation of the first hollow stem 17, ? between the annular element 19 and the separator element 24.

Figures 1 to 3 show the actuator device 10 in different arrangements: the one shown in figure 1? an intermediate working arrangement, in which the first hollow stem 17 protrudes from the head 16, to exert a thrust, and in which both the first chamber 20 and the second chamber 21 are present; in figure 2 the first hollow stem 17 ? at its maximum extension towards the outside and the magnetorheological fluid ? substantially in the first chamber 20 (and obviously in the connection zones with the other chamber), which is presented in its maximum volume; in figure 3 the first hollow stem 17 ? at the end of the stroke with the annular element 19 at bottom dead centre, in contact with the bottom 14 and the magnetorheological fluid ? substantially in the second chamber 21, which is present in its maximum volume, while the third chamber 23 and the first chamber 20 are empty and therefore absent in this arrangement. Obviously, the volumes of the rooms change in the transition between the various layouts.

The device 10 also comprises a fourth chamber 25 defined by the communicating cavities of the first hollow stem 17 and of the second hollow stem 18, these being open at a respective end. The third chamber 23 and the fourth chamber 25 are in fluid connection through through holes 26, which pass through the wall of the first hollow stem 17. They are designed to contain a fluid, chosen between compressible, for example nitrogen, and incompressible, consisting of one to be chosen for example between oil, HFC fluid (water and glycol), HFD or HFDU (water-free synthetic fluids), etc. The latter compared to the oil have conductivity? and capacity? superior thermal, favoring the dissipation of heat.

Among the various components are suitably provided (in each embodiment of the device according to the invention) per se? known sealing gaskets, such as scraper rings, o-rings, or others. To simplify the illustration, these elements are only partially numbered, with the reference 44 and in figure 1.

There is also an elastic ring, indicated with 41 in figures 1 and 3, made of elastically deformable plastic material, able to guarantee an elastic elasticity. minimum useful to compensate for volume variations in the magnetorheological fluid, in particular in the arrangement shown in figure 3. The elastic ring 41 is positioned in a groove on the annular element 19, at the interface with the third chamber 23.

On the outside, in correspondence with the opening of a channel 27 (visible in the views of figure 1 and figure 2) obtained in the bottom 14 of the jacket 11 and intercepted by the cavity? of the second hollow stem 18, ? a tank for the incompressible fluid can be connected, preferably with an independent control circuit. In particular, the channel 27 has two openings, in correspondence with one of these ? can the tank be connected with a pump and in correspondence with the other ? installed a non-return valve, or a pressure regulating valve. These two elements and the hydraulic circuit which connects them to channel 27 are not shown to simplify the illustration.

If the fluid is compressible, for example nitrogen, the two openings are closed by plugs or non-return valves. Alternatively, only one or both of the openings can? be connected to an external gas tank. In this case there may be an integrated non-return valve and a calibrated hole for controlled gas discharge.

With at least one other hole 42, two in the illustrated example, obtained on the head 16? It is possible to fill the first chamber 20 and/or the second chamber 21 with magnetorheological fluid. The holes are closed by plugs 43.

There is also another channel 28, visible in the view of figure 3, which passes through the bottom 14 and the bush 12, for the passage of an electrical connection to the electrical windings 13. In particular, this channel 28? obtained partly in the bottom 14 and partly in the bush 12, where with an inclined portion it ends in correspondence with a circular groove of the bush 12, in which ? there is a first electric winding 13.

In the channel 28 pu? there may be a fairlead, to bring electric cables or tapes from the outside to the bush 12 (as illustrated for the second embodiment), or, as illustrated, it can be be present a double connector 29, with a portion pi? external to which the electrical connection is brought and on which an electronic board and a processor are mounted (not shown to simplify the illustration) and a smaller portion? internal, more close to the first groove of the bush 12 and to which the windings 13 are electrically connected. The connector 29, inserted in the two parts of the channel 28, prevents the rotation of the bush 12 in the jacket 11.

In the lower part of the bottom 14 there are formed pockets 30 (at least one, which can be seen in Figure 3) for housing, for example, pressure and temperature sensors for controlling these quantities in the magnetorheological fluid and connected to the electronic board. The same electronic card pu? be housed in one of these pockets.

Device 10 can? in fact be equipped with such sensors (one of your choice or both), connected to a control system.

Figure 4 shows the bush 12 with windings 13. From the outside, it has a series of circular grooves 31 which are parallel and in which the electric windings 13 are housed. The distances between the grooves, therefore between the windings, may not be constant , to optimize the effectiveness of the device (obtaining a uniform magnetic flux in the length of the gap).

On compass 12 ? there is at least one passage 32 which transversely intercepts the circular grooves 31 to allow the passage of the cables or tapes from one winding to the next and to also allow their return towards the connector 29. there should be another passage to separate the return path of the cables. Step 32 ? indicated in figure 4 and in the section of figure 3, where in a simplified way ? drawn a dotted line to indicate the presence of cables. Their passage through channel 28 is not ? shown, again for simplicity?.

With reference to figures 5, 6 and 7, the device according to the invention ? indicated overall by 110 in its second embodiment.

The main difference with respect to the previous embodiment described lies in the fact that the fluid in the third chamber 123 can consist only of a compressible fluid, preferably nitrogen.

Similarly to what is described for the first embodiment, the device 110, still of the type using magnetorheological fluid, comprises a jacket 111 and inside this and concentric with it a tubular bush 112, on the outer surface of which there are electric windings 113. The jacket 111 has a tubular portion 115 and a bottom 114 (in a single body) which closes it on one side, and ? closed on the opposite side by a head 116, drilled for the passage of a first hollow stem 117.

Compass 112? provided at one end? of first spacers 138, with which it rests on the bottom 114, and of second spacers 139 on the opposite side.

The device 110 comprises the first hollow stem 117 and a second hollow stem 118. The two hollow stems 117 and 118 cooperate with each other in a telescopic manner: the first 117 ? able to protrude from the head 116 by translating on the second 118, which develops from the bottom 114 inside the bush 112. The intensity? of the electric current which runs through the electric windings 113 ? adjustable by means of an electric power supply both in non-working or set-up phases, and during the working stroke of the first hollow stem 117.

Jacket 111 and bush 112 are made of material permeable to magnetic fields (for example in the materials indicated for the previous embodiment). The 116 head can? be made of non-magnetic material and, in a different constructive variant, the bottom 114 of the shirt could also be made of non-magnetic material.

The device 110 also comprises: an annular element 119 integral with the first hollow stem 117, translating with this inside the bush 112; a first chamber 120, which develops around a portion of the second hollow stem 118, between the bottom 114 and the annular element 119 and suitable for containing magnetorheological fluid; a second chamber 121, which develops around a portion of the first hollow stem 117 and which is in fluid connection with the previous one by means of a calibrated interspace 122 between the bush 112 and the jacket 111, as already? described for the first embodiment. The cavity 122 ? passable by the magnetorheological fluid, as previously described. Still ? there is a third volume compensation chamber 123, which develops around a portion of the first hollow stem 117, separated from the second chamber 121 by means of a separator element 124, kept spaced from the edge of the bush 112 by means of the second spacers 139.

In this embodiment, the annular element 119 transversely separates the first chamber 120 from the second chamber 121.

The second room 121 ? between the annular element 119 and the separator element 124 and the third chamber 123 ? between the head 116 and the separator element 124.

The third chamber 123 contains a compressible fluid, preferably nitrogen.

The device 110 comprises a fourth chamber 125 defined by the communicating cavities of the first hollow stem 117 and of the second hollow stem 118.

The separator element 124 ? annular in shape, installed at least around a portion of the first hollow stem 117, in this case also around a head portion 116 extending around the portion of the first hollow stem 117. The separator element 124 is adapted to translate along the same axis of translation X as the first hollow stem 117, in a space substantially between the perforated wall of the head 116 and the spacers 139.

Alternatively, the separator element can? be constituted by a membrane (or similar), fixed perimetrically to the tubular walls of the cylinder head 116 extending along a section of the external surface of the first hollow stem 117 and along a section of the internal surface of the jacket 111. The tubular extensions of the cylinder head are indicated with 133 in figure 5.

Again, the fourth chamber 125 ? fillable with a fluid from the outside, on the bottom 114 there being a channel 127 which intercepts the cavity? of the second hollow stem 118, which can be connected to an external fluid tank. This fluid? preferably a compressible gas and ? suitably present a non-return valve 134, near? of the outward opening, which remains closed during operation of the device. Can? there should also be a dowel with a calibrated hole to ensure gradual decompression. Alternatively, the fluid can? be incompressible, as described for the previous embodiment, suitably connected by an external pressure source.

In the arrangement shown in figures 5 and 7 the first hollow stem 117 is in maximum extension of the device and the volume of the first chamber 120 ? maximum. In the arrangement of figure 6 the hollow stem 117 with the annular element 119 are at the bottom dead center and ? maximum volume of the second chamber 121.

The lowering of the first rod 117 involves a reduction in the volume of the fourth chamber 125, with compression of the fluid. By setting a pre-compression in the fourth chamber 125, the ascent of the first hollow stem 117 is obtained. The volume variation due to the retraction of the first stem 117? compensated by the translation of the separator element 124.

There is also another channel 128 (visible in figure 7) crossing the bottom 114 and the bush 112, for the passage of an electrical connection to the electrical windings 113. The connection can? take place with the passage of cables from the outside substantially using cable glands 135. Alternatively, the connection can? take place with one or more connectors, as shown for the previous embodiment of the device, with an electronic board and a processor. Also in this case there may be an electronic card, processors, temperature and pressure sensors connected to a control system, and pockets for housing these and other devices can be obtained on the bottom 114.

Holes 136 for filling with magnetorheological fluid are obtained on the bottom 114 and are suitably closed by plugs 137.

Compass 112? similar to the bush 12 and has, from the outside, a series of parallel circular grooves 131 in which the electric windings 113 and a passage 132 are housed, visible in figure 7. As before, the passages of the cables are simplified.

The operation of the actuator device, according to the invention ? the following.

The interspace 22, 122 ? crossed by the magnetorheological fluid, in passage from the first chamber to the second (and vice versa in the ascent of the rod), and constitutes a duct of suitable length (possibly higher than in known devices) affected by the magnetic field generated with the passage of electric current in the windings 13 , 113. The permeability? of the jacket and of the bushing to the magnetic field allows the lines of force B to close around the windings 13, 113, investing the fluid in the interspace, as shown in figure 1.

Thanks to a nominal diameter greater than the diameter of the first hollow rod 17, 117, the speed? of the fluid through the gap 22, 122 ? less than the known solution with magnetorheological fluid around the stem, advantageously reducing the contribution of viscous forces and limiting the problem of any cavitation phenomena. Furthermore, in order for cavitation does not occur in the first 20, 120 and second chamber 21, 121, due to viscous pressure drop in the interspace 22, 122, the third and fourth chamber 23, 25, in the first embodiment, and the third chamber 123 in the second embodiment, must be preloaded under pressure, thus allowing the operation of the separator element 24, 124.

The viscosity? of the fluid depends on the intensity? of the current, therefore the resistant force generated by the device pu? be modulated by varying the intensity? of current flowing through the windings and therefore the magnetic parameters, by means of the closed loop control system (in feedback), according to the parameters (pressure and temperature) measured by the sensors on the case back.

Also the position and the speed? of descent and ascent of the first hollow stem 17, 117, can be modulated by varying the magnetic parameters, varying the resisting force offered by the device and controlled by the control system, again as a function of the measured parameters.

In fact, in both embodiments, the passage of the current allows to increase the viscosity? of the magnetorheological fluid and therefore to increase the thrust of the first stem 17, 117.

In the first embodiment, the compensation of the volume difference between the chambers, first 20 and second 21, due to the movement of the hollow stem 17, and of the volume variations due to changes in temperature, takes place thanks to an internal compensation chamber, i.e. ? the third chamber 23, the volume of which changes with the translation of the separator element 24 and with the passage of fluid to the fourth chamber 25 through the hole 26. A reduction in the volume of the first chamber 20, in the descent of the rod 17, requires an increase in the volume of the second chamber 21 accompanied by a reduction in that of the third chamber 23.

The ascent of the stem 17, from the bottom dead center or from an intermediate position, takes place thanks to the precompression generated in the fourth chamber 25, with gas, or by pushing, with the pump, the incompressible fluid from the outside. In the case of an incompressible fluid, this is also, at least in part, made to escape outside in the descent phases of the hollow stem 17, facilitating the dissipation of heat. In this regard, emulsified water (HFC, HFD, HFDU, etc.) guarantees conductivity? and capacity? superior thermal compared to oil, further favoring the dissipation of heat.

In the second embodiment, the compensation of the volume difference between the two chambers, first 120 and second 121, and volume variations due to temperature changes, takes place again thanks to the third chamber 123, the volume of which changes with the translation of the separator element 124, preloaded with gas (for example nitrogen), which allows to obtain a preload pressure also in the chambers in which ? the magnetorheological fluid contained.

The ascent of the first stem 117 occurs thanks to the pre-compression in the fourth chamber 125.

Current can flow through the windings even in non-working or set-up phases (possibly also by modulating the current intensity) in order to heat the device and/or the magnetorheological fluid, avoiding working in critical temperature fields for the viscosity of the fluid itself and avoiding transitory phases due to the change of the viscosity?.

It is evident how, in both embodiments, the possibility? to act instant by instant on the intensity? of current that runs through the windings allows you to change the viscosity? of the magnetorheological fluid and therefore its speed? through the interspace, obtaining instantaneous control and modulation of the thrust and/or resistance force offered by the first rod during its stroke.

The device ? therefore controllable both in an active way, for example in the ascent stroke of the stem to perform a controlled extraction of a product from a mold, by controlling the speed? of ascent (which otherwise would be controlled exclusively by the thrust of the fluid in the fourth chamber), and in a semi-active manner, for example to obtain a constant descent when applied to a blank holder.

Being present windings on a fixed part of the device, the cio? the compass, these do not imply technical complications (they make connection to the electric power source easier) and the useful working length in which the fluid is magnetized ? greater, compared to known devices, allowing the application of forces more? while helping to make the device compact.

The third chamber (internal compensation) also helps to make the device compact and reduces the risk of leaks, because? it does not require external connections (as would happen with an external compensator).

The push force? controllable and modulable even in the unloading phase (which in other devices increases with the stroke), to the benefit of operator safety.

Yes ? in practice it has been observed that the invention achieves the intended aim and objects, providing an actuator device of contained dimensions, capable of exerting an instantaneously modulable thrust force, thus as well as the speed? and the rising position of the stem, allowing adequate control of the movement of the machine parts and avoiding harmful loads for the mechanical parts and dangerous and harmful situations of instantaneous release of stored energy, at the same time also overcoming the limits of magnetorheological fluid devices of known type.

The found, what? conceived, ? susceptible to numerous modifications and variations, all of which are within the scope of the inventive concept; furthermore, all the details may be replaced by other technically equivalent elements.

In practice, the materials used, provided? compatible with the specific use, as well as? the contingent dimensions and shapes may be any according to the requirements and to the state of the art.

Where features and techniques mentioned in any claim are followed by reference marks, have those marks been affixed for the sole purpose of enhancing intelligibility? of the claims and consequently such reference marks have no limiting effect on the interpretation of each element identified by way of example by such reference marks.

Claims (17)

1. Actuator device, of the type using magnetorheological fluid, characterized in that it comprises at least the combination of: - a shirt (11, 111), - a bush (12, 112), tubular, inside said jacket (11, 111) and concentric with it, on the outer wall of said bush (12, 112) being present electric windings (13, 113), said jacket (11 , 111) being closed on one side by a bottom (14, 114) and on the opposite side by a head (16, 116) perforated for the passage of - a first hollow stem (17, 117) capable of protruding from said head (16, 116) by translating onto - a second hollow stem (18, 118) extending from said bottom (14, 114) inside said bush (12, 112 ), said first and second hollow stem (17, 117, 18, 118) cooperating with each other in a telescopic way, - an annular element (19, 119) integral with said first hollow stem (17, 117), translating with it inside said bush (12, 112), - a first chamber (20, 120), which develops around a portion of said second hollow stem (18, 118), between said bottom (14, 114) and said annular element (19, 119) and able to contain said magnetorheological fluid, - a second chamber (21, 121), which develops around a portion of said first hollow stem (17, 117) and which ? in fluid connection with said first chamber (20, 120) through a gap (22, 122) between said bush (12, 112) and said jacket (11, 111), - a third volume compensation chamber (23, 123). 2. Device, according to claim 1, characterized in that said third chamber (23, 123) develops at least around a portion of said first hollow stem (17, 117), separated from said second chamber (21, 121) by a separator element (24, 124). 3. Device, according to one or more? of the preceding claims, characterized in that said annular element (19) transversely separates said first chamber (20) from said third chamber (23). 4. Device, according to one or more? of the preceding claims, characterized in that said annular element (119) transversely separates said first chamber (120) from said second chamber (121). 5. Device, according to one or more? of the preceding claims, characterized in that it comprises a fourth chamber (25, 125) defined by the communicating cavities of said first and said second stem (17, 117, 18, 118). 6. Device, according to one or more of the preceding claims, characterized in that said jacket (11, 111) and said bush (12, 112) are made of material permeable to magnetic fields. 7. Device, according to one or more? of the preceding claims, characterized in that said separator element (24, 124) ? having an annular shape and installed at least around a portion of said first hollow stem (17, 117). 8. Device, according to one or more of the preceding claims, characterized in that said separator element (24, 124) ? adapted to translate along a translation axis (X) of said first hollow stem (17, 117). 9. Device, according to one or more? of the preceding claims, characterized in that it has a channel (28, 128) passing through said base (14, 114) and said bush (12, 112), for the passage of an electrical connection to said electrical windings (13, 113). 10. Device, according to one or more? of the preceding claims, characterized in that said bush (12, 112) has, from the outside, a series of parallel circular grooves (31, 131) in which said electric windings (13, 113) are housed. 11. Device, according to one or more? of the preceding claims, characterized in that said second chamber (21) ? comprised between said head (16) and said separator element (24) and said third chamber (23) ? comprised between said annular element (19) and said separator element (24). 12. Device, according to one or more? of the preceding claims, characterized in that said third chamber (23) and said fourth chamber (25) are in fluid connection through at least one through hole (26) which passes through the wall of said first hollow stem (17), and are designed to contain a fluid, either incompressible or compressible. 13. Device, according to one or more? of the preceding claims, characterized by the fact that said incompressible fluid ? consisting of a fluid chosen from oil, HFC, HFD, HFDU. 14. Device, according to one or more? of the preceding claims, characterized in that said second chamber (121) is comprised between said annular element (119) and said separator element (124) and said third chamber (123) ? between said head (116) and said separator element (124). 15. Device, according to one or more? of the preceding claims, characterized in that said third chamber (123) contains a compressible fluid. 16. Device, according to one or more? of the preceding claims, characterized in that it comprises at least one pressure sensor and/or at least one temperature sensor, connected to a control system. 17. Device, according to one or more? of the previous claims, characterized by the fact that the intensity? of the electric current which runs through said electric windings (13, 113) ? modulable by means of an electric power supply.