Control unit for controlling an actuator device and combination of an actuator device and a control unit

Abstract

A control unit (100; 200; 300; 300a; 400, 400a) for controlling an actuator device is described, said control unit comprising: a tubular body (101; 201; 301; 401) defining an axial cavity (101a; 201a; 301a; 401a), said tubular body being closed at an end thereof by a base (102; 202; 302; 402) and at the axially opposite end by a head (103; 203; 303; 403), a tubular bush (105; 205; 305; 405) arranged inside said cavity and coaxial with said tubular body, a separator element (106; 206; 306; 406) arranged in the cavity and suitable for separating in a fluid-tight manner a first chamber (108; 208; 308; 408) from a second chamber (109; 209; 309; 409) defined in said tubular body, a passage (110; 210; 310; 410) being provided in said cavity between said tubular body (101; 201; 301; 401) and said tubular bush (105; 205; 305; 405), said passage (110; 210; 310; 410) being in fluid connection with the first chamber (108; 208; 308; 408), a first fluid with magnetorheological behaviour being provided in said first chamber (108; 208; 308; 408), a system of electrical windings (115; 215; 315; 415) provided for generating, when passed through by electrical current, a magnetization at said passage (110; 210; 310; 410) so as to vary the flowing capacity of said first fluid through said passage, and to generate a flow rate and / or a pressure in said first fluid suitable for controlling the movement of said actuator device and / or the forces acting on said actuator device, when said actuator device is operationally connected to said control unit, said second chamber (109; 209; 309; 409) being provided with a second fluid suitable for generating a pressure for acting counter to the pressure existing in the first chamber (108; 208; 308; 408) during the operational function of said control unit.

Description

[0001] CONTROL UNIT FOR CONTROLLING AN ACTUATOR DEVICE AND COMBINATION OF AN ACTUATOR DEVICE AND A CONTROL UNIT

[0002] Technical field

[0003] The present invention relates to a control unit for controlling an actuator device.

[0004] The invention further relates to a combination of such a control unit and an actuator device configured to be controlled by said control unit.

[0005] Technological background

[0006] The invention finds particular, though not exclusive, application in the industrial field of machine tools such as presses, e.g., for forming or punching machining, in the technical field of dies and die components (e.g., blank holders), or in general in machines requiring the damping of dynamic phenomena (vibrations) or the application of dissipative forces.

[0007] Actuator systems designed to work in relative coupling and subject to centralised control are known to be used in such contexts. Examples include hydraulically controlled single-action linear actuators.

[0008] The term 'dependent actuator' generally refers to an actuator device on which, exerting a certain displacement on the moving part, by means of elements connected thereto, a flow rate is produced towards a control unit which allows to control the pressure in the actuator itself, enabling the latter to exert a force and velocity on the system to which it is connected.

[0009] The type of 'dependent actuator' to which the present invention relates differs from 'independent actuators', in which exerting a certain displacement of the movable part by means of elements connected thereto produces a flow rate towards a volume compensation unit, the pressure resisting the flow of the flow rate being controlled within the actuator itself. In the case of a system of dependent actuators, flow rate and pressure, generated by a device or control unit, they can be controlled dynamically and are shared by all the actuators, thus allowing the same instantaneous pressure and flow rate to be exerted by means of the dependent actuator devices, controlling the movement thereof and the forces which are exchanged by the system itself. In this case, the device or control unit is also referred to as semi-active, meaning a device suitable for applying a force on the system to which it is connected without the input of external energy, such that the force is generated as a reaction to the behaviour of the system or stored therein, being able to be adjusted during operation when necessary.

[0010] In contrast, in the case of a system of independent actuators, the resistant pressure which determines the force to each actuator can be controlled independently and dynamically in each individual actuator, while the compensation unit can consist of a simple vessel for the instantaneous accumulation of volume to and from the actuators. Similarly, during the return step, the resistance to the flow rate in input and thus the speed of each individual independent actuator can be adjusted dynamically and independently.

[0011] 'Double-action devices' in the art refers to devices (cylinders) which have two chambers in which to make the pressurised fluid act alternately, so as to exploit the thrust thereof during both the working stroke of the shank and during the repositioning stroke.

[0012] It is known that during a deep-drawing operation, since the area on which the blank holder (member responsible for preventing the formation of wrinkles on the sheet metal) acts decreases as the sheet metal progresses through the die and, in general, in a different manner during the stamping stroke, the force is required to follow a particular law as a function of the stamping stroke, typically decreasing. In the case of components with complex geometry, it may be required that such blank holder forces have different values in different zones during the stamping stroke. The use of damping devices inside presses is known, e.g., to assist dies or die components.

[0013] Again, eccentric loads can be generated during a stamping process, leading to overloading of the guides and misalignment of the dies to the detriment of the precision of the stamped part.

[0014] In a shearing process, when a fracture occurs, there is an instantaneous release of energy stored in the structure of the press during the process, which leads to noise, vibrations and consequent possible damage to mechanical or hydraulic components, forcing a preventive over-dimensioning of the dies or the machines themselves.

[0015] In the case of a press, the blank holder ring is suitable for transmitting a force to the sheet metal to counter the movement of the upper half-die of the press. The blank holder is supported by tubes, which in turn are supported by a blank holder cushion. In the most common press construction, the lower table, with the lower half-die, is fixed, while a slide pushes the blank holder. The cushion, in the art also known as 'caisson', is mounted on actuators, in the industry also known as blank holder pistons, which act against the downward movement of the slide.

[0016] Today, pneumatic cylinders connected to air tanks are often used for the above applications. During the stroke of the slide, the air is compressed, ensuring the required force for the blank holder (passive phase) and the subsequent rise (active phase). The force regulation is limited to the regulation of the initial pressure.

[0017] These solutions have a number of not insignificant drawbacks, including the fact that:

[0018] - the reaction force is not constant but increases during the stamping stroke, thus in the opposite manner to what is generally required;

[0019] - since it is not possible to control the rising phase, in the event of a jam or damage, the presence of residual pressure can lead to uncontrolled movement of the blank holder when the problem is resolved, and any pressure discharge would require time that is not compatible with the time needed to prevent accidents;

[0020] - large sizes;

[0021] - generation of damaging reverse loads acting on mechanical members, in the mechanical presses, requiring a braking action by the machine motor, with consequent energy dissipation and thermal overload of the motor itself,

[0022] - in hydraulic presses, a shank braking action is required to control the retraction movement of the blank holder in order to limit the rising speed, with consequent energy dissipation and an increase in the press processing cycle time.

[0023] Other blank holder cylinders are hydraulically controlled. In this case, with respect to the previous one, it has smaller sizes and adequate control technology (sensors, valves and control software / hardware, etc.) which allow to modulate the pressure in the cylinders. However, even these are not without drawbacks, in particular the relatively high costs and the generation of heat to be disposed of (due to fluid lamination). The use of nitrogen-filled cylinders (also known in the art as 'springs') is also known, whose space requirements are limited, especially when the tank is obtained in the cylinder itself, but the limitations of air blank holder cylinders remain.

[0024] Other known solutions include:

[0025] - spring actuators, which can only be used for small strokes and low forces and are unable to absorb the vibrations which may be generated during the process;

[0026] - anti-shock devices (for shearing), i.e., oil actuators with a dissipative valve to dampen vibrations, but with limited strokes due to the incompressibility of the fluid.

[0027] A possible solution is represented by semi-active actuators using magnetorheological fluid (typically mineral oil with metal powder dispersion), in which the fluid passes between two chambers by means of calibrated passages in the piston head. The fluid changes its viscosity when subjected to a magnetic field, to generate the required resistance, which can be induced by the passage of current in cables passing through the shank, which, depending on the application, forms the movable or fixed part of the actuator. These devices are used, for example, in the automotive and aeronautical sectors, as vibration dampers and shock absorbers, where high performance is required, due to the typical reaction speed of magnetorheological fluids to changes in current and thus the magnetic field.

[0028] A solution based on this technology already exists in the background art and is the subject of Italian patent no. 102021000002114 in the name of the same Applicant. With the solution described therein, many of the technical limitations found in previous technologies have been overcome. The management cost and complexity resulting from the need to use all independent actuator devices as described in the aforementioned prior patent may not be justified by the complexity of the type of component to be produced, where it might instead be sufficient to have a single behaviour for all the actuators present or at most a limited number of zones with different behaviour, or even to arrange actuators with independent behaviour but of minimum size, transferring part of the required functions to an element external to the actuators themselves.

[0029] Description of the invention

[0030] The primary aim of the present invention is to provide a control unit for controlling one or more actuator devices, which is structurally and functionally designed to overcome the limitations stated with reference to the aforementioned prior art.

[0031] This and other aims which will appear more clearly below are achieved by a control unit for controlling an actuator device having the characteristics defined in the appended claim 1.

[0032] The characteristics defined in the dependent claims refer to embodiment examples of the invention.

[0033] The invention advantageously allows to make a particularly compact system of dependent actuators comprising an external control unit which, acting as a pressure and flow rate source, is able to control these variables dynamically.

[0034] This solution allows one or more dependent actuators within a die to be powered the same control unit, obtaining an overall device that is less expensive with respect to a solution involving the management of all independent actuators.

[0035] In a possible configuration thereof, the control unit of the present invention can be associated with the press instead of directly with the die, thus being able to be connected to dependent actuators or those present in several dies.

[0036] Furthermore, the control unit of the invention, being able to be arranged in remote zones with respect to the die, does not present appreciable constraints in terms of geometry as in the case of actuators housed inside the die, to the advantage of a greater freedom of choice in the technical solutions adopted, in particular achieving a more compact design of the actuator itself, especially in the case of dependent actuators.

[0037] Furthermore, the volume compensation function generated by the stroke of the actuators can be achieved by separating the different fluids operating within the control unit by means of resilient elements, such as membranes or bags made of rubber or another highly deformable material, ensuring high system reliability and low implementation costs.

[0038] The invention thus allows to make a compact system of actuators, which, taking advantage of the presence of an external control unit suitable, in the case of a dependent actuator system, for dynamically controlling one or more actuator devices with the same pressure and flow rate, can advantageously be of compact size and low cost, and whose thrust force can be quickly, easily and effectively modulated, as can the rising speed and position of the shank.

[0039] The invention also allows to make a compact system of actuators suitable for dampening vibrations of the machine parts to which it is applied and / or to exert reaction forces to counter the movement of the machine parts to which it is applied, e.g., to counter rotations of stamping machine parts under eccentric loads or to control the stroke thereof.

[0040] The invention also allows to make a compact system of actuators consisting of one or more dependent actuator devices and a control unit, in which the thrust force of the actuators themselves can be modulated moment by moment.

[0041] The invention allows to make a compact system of actuators consisting of one or more dependent actuator devices and a control unit, in which it is possible to avoid dangerous and damaging situations of instantaneous release of stored energy in the structures in which it is applied.

[0042] The invention allows to make a compact system of actuators consisting of one or more dependent actuator devices and a control unit with a smaller size and lower cost with respect to other similar systems known to date.

[0043] The invention further allows to make a compact system of actuators consisting of one or more actuator devices and a control unit capable of limiting energy dissipation in the machines in which it is applied and increasing machine processing cycle time.

[0044] The invention also allows to make a compact system of actuators consisting of one or more dependent actuator devices and a control unit suitable for dynamically controlling one or more actuator devices, which is highly reliable, relatively easy to make and at competitive costs.

[0045] In accordance with a first aspect, the invention relates to a control unit for controlling an actuator device.

[0046] Preferably said control unit comprises a tubular body defining an axial cavity.

[0047] Preferably said tubular body is closed at one end by a base and at the axially opposite end by a head.

[0048] Preferably said control unit comprises a tubular bush arranged internally to said cavity and coaxial with said tubular body.

[0049] Preferably, said control unit comprises a separator element arranged in the cavity and suitable for separating in a fluid-tight manner a first chamber from a second chamber defined in said tubular body.

[0050] Preferably a passage is provided in said cavity between said tubular body and said bush.

[0051] Preferably said passage is in fluid connection with the first chamber.

[0052] Preferably, a first fluid with magnetorheological behaviour is provided in said first chamber.

[0053] Preferably, said control unit comprises a system of electrical windings provided for generating, when passed through by an electrical current, a magnetization at said passage so as to vary the flowing capacity of said first fluid through said passage, and generating a flow rate and / or a pressure in said first fluid suitable for controlling the movement of said actuator device and / or the forces acting on said actuator device, when said actuator device is operationally connected to said control unit.

[0054] Preferably, a second fluid is provided in said second chamber suitable for generating a pressure for acting counter to the pressure existing in the first chamber during the operational function of said control unit.

[0055] Preferably said bush is fixedly joined to said tubular body.

[0056] Preferably said passage comprises a gap having an axial section with an annular formation.

[0057] Preferably said second fluid is a fluid of the compressible type.

[0058] Preferably the second fluid is an inert gas.

[0059] Preferably, said separator element comprises a piston slidingly mounted inside said bush in a fluid-tight manner.

[0060] Preferably said separator element comprises a resilient membrane delimiting a closed volume and said second chamber is defined in said volume.

[0061] Preferably said passage is in communication with an opening of said unit which is outwardly open, through which said first fluid is made available for controlling an actuator device when operationally connected to said control unit.

[0062] Preferably, said control unit comprises a third chamber and a fourth chamber as well as a second separator element suitable for separating said third chamber from said fourth chamber in a fluid-tight manner.

[0063] Preferably said third chamber is in fluid connection with said first chamber by means of a connection channel of said passage with said third chamber.

[0064] Preferably, a third fluid is provided in said fourth chamber which is intended to supply an actuator device when said actuator device is operationally connected to said control unit.

[0065] Preferably, said second separator element comprises a respective second piston slidingly mounted in said unit in a fluid-tight manner.

[0066] Preferably, said second piston is slidingly engaged in a fluid-tight manner in an extension body of said unit fixedly joined to said base.

[0067] Preferably said second separator element comprises a respective second resilient membrane delimiting a closed volume and said fourth chamber is defined in said volume.

[0068] Preferably said fourth chamber is in communication with an opening of said unit which is outwardly open, through which said third fluid is made available for controlling the actuator device when operationally connected to said control unit.

[0069] In accordance with another aspect, the invention relates to a combination of an actuator device and a control unit of said device comprising an actuator device with a single-action hydraulic cylinder and a control unit in accordance with the foregoing aspects.

[0070] Preferably said actuator device is configured as a linear actuator.

[0071] Preferably said combination of an actuator device and a control unit of said device comprises an actuator device with a single-action hydraulic cylinder, said actuator device comprising a piston with an actuator shank, said piston delimiting an operating chamber configured to be connected, in fluid connection, by means of a pipe, to said opening of said control unit so that said operating chamber is supplied with said first fluid.

[0072] Preferably said combination of an actuator device and a control unit of said device comprises an actuator device with a single-action hydraulic cylinder, said actuator device comprising a piston with an actuator shank, said piston delimiting an operating chamber configured to be connected, in fluid connection, by means of a pipe, to said opening of said control unit so that said operating chamber is supplied with said third fluid.

[0073] Brief description of the drawings

[0074] The characteristics and advantages of the invention will become clearer from the following detailed description of some of preferred embodiments thereof, shown by way of non-limiting example, with reference to the accompanying drawings, wherein:

[0075] Figure 1 is a longitudinal sectional view of a first example of a control unit in accordance with the invention, Figure 2 is a side elevation and partial section view of the control unit of

[0076] Figure 1,

[0077] Figure 3 is a plan view of the control unit of the previous figures ,

[0078] Figure 4 is a longitudinal sectional view of a second example of a control unit in accordance with the invention,

[0079] Figure 5 is a side elevation and partial section view of the control unit of

[0080] Figure 4,

[0081] Figure 6 is a longitudinal sectional view of a third example of a control unit in accordance with the invention,

[0082] Figure 7 is a side elevation and partial section view of the control unit of

[0083] Figure 6,

[0084] Figure 7A is a plan view of the control unit of Figure 6,

[0085] Figure 7B is a further longitudinal sectional view of the control unit of

[0086] Figures 6, 7 and 7A, according to section line VII-VII of Figure 7A,

[0087] Figure 8 is a longitudinal sectional view of a fourth example of a control unit in accordance with the invention,

[0088] Figure 9 is a side elevation and partial section view of the control unit of

[0089] Figure 8,

[0090] Figure 10 is a longitudinal sectional view of an actuator device configured to be controlled by the control unit of the invention,

[0091] Figures 11 and 12 are side elevation and plan views of the actuator device of Figure 10, respectively,

[0092] Figure 13 is a longitudinal sectional view of an embodiment of the actuator device configured to be controlled by the control unit of the invention,

[0093] Figure 14 is a schematic view of a combination of the actuator device of Figure 10 and the control unit of Figure 1, shown in functional connection with each other,

[0094] Figures 15 and 16 are plan views from the top and in side elevation of an embodiment variant of the example of Figure 6, respectively,

[0095] Figure 17 is a longitudinal sectional view according to the section line XVII- XVII of Figure 16.

[0096] Figures 18 and 19 are plan views from the top and in side elevation of an embodiment variant of the example of Figure 8, respectively,

[0097] Figure 20 is a longitudinal sectional view according to the section line XX- XX of Figure 19.

[0098] Preferred embodiments of the invention

[0099] With reference to the above-mentioned figures, a first example of a control unit made in accordance with the present invention, for controlling an actuator device, is overall indicated with 100.

[0100] The control unit 100 comprises a tubular body 101 defining an axial cavity 101a extending longitudinally along an axial direction X. The tubular body 101 is closed at an end thereof by a base cap 102 and the axially opposite end thereof is closed by a head 103.

[0101] Said control unit 100 further comprises a tubular bush 105 arranged internally to the cavity and coaxial therewith.

[0102] The base 102 and the head 103 are preferably made of non-magnetic material and are provided with spacer feet so as to make axial gaps are created between the base and the bush, by means of spacer feet 102a, and between the head and the bush, by means of spacer feet 103a.

[0103] A separator element 106, configured as a piston, is arranged internally to the bush and is slidingly engaged (in the axial direction X) in a fluid-tight manner on the inner cylindrical surface of the bush 105.

[0104] Said separator element 106 is suitable for separating, in a fluid-tight manner, a first chamber 108 from a second chamber 109, both defined in the tubular body.

[0105] In more detail, the first chamber 108 is partly extended inside the bush, between the separator element 106 and the head 103, while the second chamber 109 is extended inside the bush, between the separator element 106 and the base 102.

[0106] In the cavity 101a, a passage 110 is provided between the bush and the tubular body, formed as a gap with an annular crown section, extended along substantially the entire axial extension of the bush.

[0107] The passage 110 is in fluid connection with the first chamber 108, at an axial end of the bush, and is also in fluid connection, at the opposite axial end of the bush, with a cavity 111, which is in turn in communication, through a connection channel 112, with an opening 113 open outwardly of the unit. Said opening 113 is arranged to be selectively intercepted.

[0108] There is a first fluid with magnetorheological behaviour in the first chamber 108.

[0109] A system of electrical windings, indicated with 115, is provided at the passage 110, said windings being arranged to generate, when passed through by electrical current, a magnetization in the region of the passage 110 so as to vary the flowing capacity of the magnetorheological fluid transiting along the passage.

[0110] More in particular, the electrical windings 115, e.g., electrical tapes or cables, are housed in respective circular grooves 116 obtained on the outer cylindrical surface of the bush 105. Said grooves 116 are conveniently obtained with a pre-determined axial pitch, preferably regular, on the outer surface of the bush.

[0111] For the sake of illustrative simplicity, in the sectional view of Figure 1, the windings 115 housed in the grooves 116 are schematically depicted by means of a filling dashed line in the corresponding grooves. This same depiction mode is replicated in the remaining enclosed figures, in which said windings are shown.

[0112] There is a second fluid of an auxiliary type in the second chamber 109, preferably compressible, e.g., an inert gas such as nitrogen. Alternatively, the chamber 109 can be filled with an incompressible fluid, e.g., hydraulic oil or fluid emulsions of the HFC (water and glycol), HFD or HFDU (water-free synthetic fluids) type, in this case preferably providing a connection of the chamber to an external source of pressure and flow rate.

[0113] Through the opening 113, the control unit 100 can be operationally connected to an actuator device 150, conveniently of the single-action type, schematically depicted in Figure 14 in combination with the control unit 100.

[0114] In an embodiment, shown in Figures 10-12, the actuator device 150 comprises a piston with an actuator shank 151, which is slidingly engaged in a fluid-tight manner, by means of the interposition of seals, in a guide element 152. Said guide element 152 is connected in a cylindrical cup-shaped body 153, inside which the piston delimits a working chamber 154, which is in communication with the outside by means of an opening 155.

[0115] Through a pipe 156, connected with an end thereof to the opening 113 of the control unit and connected with the opposite end to the opening 155 of the actuator device, the chamber 108 of the control unit is placed in fluid connection with the working chamber of the actuator device, for the functional control of the latter, as will be described in detail below.

[0116] It should be emphasised that the control unit is conceived as a separate and distinct unit from the one or more actuator devices.

[0117] It is understood that the control unit can be connected to several actuator devices provided for a specific application. For example, it can be envisaged that the pipe 156 connects the opening 113 of the control unit with a distributor (not shown), from which the respective pipe extends connecting with the respective working chambers of the corresponding actuator devices.

[0118] This type of application can occur when said actuator devices are intended to control the movement of a die or the components of a die in a stamping press. During the working phase of the die, the shanks 151 of the actuators 150 are pushed inside the respective cylindrical bodies 153, in this case filled with the first fluid with magnetorheological behaviour, generating an output flow rate from the openings 155 of each individual actuator 150 towards the control unit 100.

[0119] Such a flow rate of fluid with magnetorheological behaviour in input to the control unit 100 through the opening 113 (or several openings 113 if envisaged) passes through the base 102 to the calibrated passage gap 110 up to the chamber 108.

[0120] When the passage gap 110 is passed through by the fluid with magnetorheological behaviour (in the passage from the cavity 111 to the chamber 108 and vice versa), the gap being affected by the magnetic field generated by the passage of electrical current in the electrical windings 115, a counterpressure is generated to the flow of the fluid with magnetorheological behaviour which produces through the actuator devices 150 the resistant force transmitted to the part of the die to which they are fixedly joined.

[0121] The flow rate of fluid with magnetorheological behaviour, having passed through the gap 110, flows into the chamber 108 causing the downward stroke of the piston 106. Such a stroke is counteracted by the pressure acting in the chamber 109. Such pressure, as described above, can be achieved by means of the second compressible auxiliary fluid, typically a gas, e.g., nitrogen, enclosed in the chamber 109, isolated therein or possibly connected to an external source, or an incompressible fluid such as hydraulic oil or fluid emulsions of the HFC, HFD or HFDU type, in this case connected to an external source of pressure and flow rate.

[0122] In the return phase of the press, the pressure acting in the chamber 109 can advantageously be used to push the fluid with magnetorheological behaviour backwards, from the chamber 108 through the gap 110 to the cavity 111 and then through the connection pipes 156 in the chamber 154 of the actuator cylinders 150, causing the exit or return stroke of the corresponding shanks 151.

[0123] In both the work and return phases, the intensity of the electrical current flowing through the electrical windings 115 can be either of fixed regulation, of the on-off type, or modulated by means of an electronic power source. The windings 115 can also be powered separately by power supply groups, but distinct for the different winding series.

[0124] Returning to some construction aspects of the control unit 100, the spacers 102a, 103a, can be made integrally in the body of the base 102 and the head 103, respectively, or they can be made in an additional spacer, a solution not depicted in the figures. By maintaining the distance between the base 102 and the head 103 and the upper edge of the tubular part of the bush 105, said spacers allow the passage of the magnetorheological fluid to and from the gap 110 and prevent the translation of the bush 105 in the axial direction. Furthermore, they can provide the coaxial centring of the bush 105 with respect to the tubular body 101.

[0125] The tubular body 101 and the bush 105 are made of material permeable to magnetic fields, preferably low-carbon steel, pure iron or other alloys specifically for magnetic applications, thereby allowing the passage and the closure of the force lines of the magnetic field generated around the windings passed through by current, hitting the fluid in the passage gap 110.

[0126] The base 102 and the head 103 can be made of non-magnetic material and, in a different construction variant, only the spacers 102a, 103a, if not made in a single piece respectively with the base 102 and the head 103, can advantageously be made of non-magnetic material.

[0127] An embodiment variant of the actuator device 150 is shown in Figure 13 and globally labelled 150'.

[0128] The actuator device 150', also made as a single-action actuator, comprises an actuator shank 151', shaped as an overturned cylindrical cup, fitted, with sliding engagement in a fluid-tight manner, by means of interposed seals, on a guide element 152'.

[0129] Said guide element 152', made in a cylindrical cup-shaped body 153', defines together with the shank 151', a working chamber 154', which is in communication with the outside, by means of an opening 155'. The opening 155' is placed in communication with the chamber 154' by means of a connection channel 157'.

[0130] The number 158' is used to indicate a pin centrally fixed inside the cylindrical cavity of the shank 151' which has a head 159' slidingly guided inside a cylindrical seat 160' made in a portion 161' of the guide element 152'. Said portion 161' is conveniently arranged internally to the body 153' and coaxial therewith.

[0131] With reference to Figures 4 and 5, a second example embodiment of the control unit in accordance with the invention is globally labelled 200.

[0132] For ease of reading, in this second example details similar to those in the first example will, unless otherwise indicated, be labelled with the reference number referring to the first example, increased by 100. Thus, for example, the tubular body of the control unit, which in the first embodiment example is labelled 101, in the second embodiment example is labelled 201.

[0133] The control unit 200 mainly differs from the control unit 100 of the previous example, in that the separator element, indicated with 206, comprises a resilient membrane delimiting a closed volume, within which the second chamber 209 remains defined.

[0134] In more detail, the membrane of the separator 206 is flexible and assumes a substantially bag-like formation, as clearly illustrated in Figure 4.

[0135] Unlike the first example embodiment described, in the control unit 200 the function of the compensation piston (carried out by the separator 106 of the control unit 100) is achieved by the bag separator 206 which separates the fluid with magnetorheological behaviour, present outside the bag, from the auxiliary fluid contained inside the bag.

[0136] The auxiliary fluid remains isolated inside the bag or the bag can be connected to an external source, if necessary. Preferably the auxiliary fluid is a compressible fluid. Alternatively, an incompressible fluid such as hydraulic oil or fluid emulsions of the HFC, HFD or HFDU type can be provided, in this case connected to an external source of pressure and flow rate.

[0137] During the working phase of the die, the shanks 151 of the actuators 150 are pushed inside the respective cylindrical bodies 153, in this case filled with the fluid with magnetorheological behaviour, generating an output flow rate from the openings 155 of each individual actuator 150 towards the control unit 100. Such a flow rate of the fluid with magnetorheological behaviour in input to the control unit 200 through the opening 213 (or several openings 213 if envisaged) passes through the base 202 to the calibrated passage 210 up to the chamber 208.

[0138] When the passage gap 210 is passed through by the fluid with magnetorheological behaviour (in the passage from the cavity 211 to the chamber 208 and vice versa), the gap being affected by the magnetic field generated by the passage of current in the electrical windings 215, a counterpressure is generated to the flow of the fluid with magnetorheological behaviour which produces through the actuator devices 150 the resistant force transmitted to the part of the die to which they are fixedly joined.

[0139] The flow rate of fluid with magnetorheological behaviour, having passed through the gap 210, flows into the chamber 208 leading to a consequent reduction in the volume of the chamber 209 (internal volume of the bag 206). Such a change in volume is counteracted by the pressure acting in the internal volume of the bag, i.e., in the chamber 209. In the return phase of the press, the pressure acting in the chamber 209 can advantageously be used to push the fluid with magnetorheological behaviour, from the chamber 208 through the gap 210 to the cavity 211 and then through the connection pipes 156 in the chamber 154 of the actuator cylinders 150, causing the exit or return stroke of the corresponding shanks 151.

[0140] Also in this example, it is intended that the control unit 200 is operationally connected to the actuator cylinders 150 by means of pipes connecting the opening 213 of the control unit with the respective working chambers of the corresponding actuator devices.

[0141] With reference to Figures 6, 7, 7A and 7B, a third embodiment of the control unit in accordance with the invention is globally labelled 300.

[0142] In this third example, details similar to those in the first example will be labelled, unless otherwise indicated, by the reference number of the first example increased by 200. Thus, for example, the tubular body of the control unit, which in the first embodiment example is labelled 101, in the third embodiment example is labelled 301.

[0143] The control unit 300 mainly differs from the control unit 100 of the first example in that it comprises a third chamber 330 and a fourth chamber 340 separated from each other by a second separator element 345. Said separator element 345 is preferably configured as a piston slidingly mounted in a fluid- tight manner, by means of one or more seals, inside a body 347 extending the tubular body 301 and fixedly joined therewith.

[0144] The chambers 330, 340 are defined within an axial cavity 348 of the body 347, the separator piston 345 being slidingly engaged in said cavity to separate the chambers.

[0145] The third chamber 330 is in fluid connection with the first chamber 308 by means of a connection channel 350. In more detail, the channel 350 puts the chamber 330 in communication with a cavity 355, which in turn is in communication with the passage gap 310 communicating with the first chamber 308.

[0146] In the chambers 308 and 330, the magnetorheological fluid can therefore be transferred from one chamber to the other through the passage gap 310.

[0147] The fourth chamber 340 is in communication, through a connection channel 312, with an opening 313 open outwardly of the unit. Said opening 313 is arranged to be selectively intercepted.

[0148] There is a third auxiliary fluid in the chamber 340, preferably an incompressible fluid, e.g., hydraulic oil or HFC, HFD or HFDU type oil.

[0149] Through a pipe (not shown and entirely analogous to the pipe 156) connected with an end thereof to the opening 313 of the control unit 300 and connected with the opposing end to the opening 155 of the actuator device 150 (or to the opening 155' of the actuator variant 150'), the chamber 340 of the control unit 300 is placed in fluid connection with the working chamber of the actuator device, for the functional control of the latter as will be described in detail below.

[0150] It is understood that the control unit 300 can be connected to several actuator devices 150 provided for a specific application. For example, it can be envisaged that the aforementioned pipe connects the opening 313 of the control unit 300 with a distributor, from which respective connection pipes extend to the respective working chambers of the corresponding actuator devices.

[0151] This type of application can occur when said actuator devices are intended to control the movement of a die or the components of a die in a stamping press. During the die working phase, the shanks 151 of the actuators 150 are pushed inside the respective cylindrical bodies 153, in this case filled with the third auxiliary fluid, generating an output flow from the openings 155 of each individual actuator 150 towards the control unit 300.

[0152] Such a flow rate of auxiliary fluid in input to the control unit 300 through the opening 313 (or several openings 313 if envisaged) results in a translation stroke of the piston 345 and an increase in the volume of the chamber 340 with a consequent reduction in the volume of the chamber 330, communicating with the cavity 355 by means of the channel 350, which then generates a net flow rate of fluid with magnetorheological behaviour through the calibrated passage gap 310 up to the chamber 308.

[0153] When the passage gap 310 is passed through by the fluid with magnetorheological behaviour (in the passage from the chamber 330 to the chamber 308 and vice versa), the gap being affected by the magnetic field generated by the passage of current in the electrical windings 315, a counterpressure is generated to the flow of the fluid with magnetorheological behaviour which produces the resistant force through the actuator devices 150, transmitted to the part of the die to which they are fixedly joined.

[0154] The flow rate of fluid with magnetorheological behaviour, having passed through the gap 310, flows into the chamber 308 causing the downward stroke of the piston 306. Such a stroke is counteracted by the pressure acting in the chamber 309. Such pressure, as described above, can be achieved by means of the second compressible auxiliary fluid, typically a gas such as nitrogen, enclosed in the chamber 309, isolated therein or possibly connected to an external source, or an incompressible fluid such as hydraulic oil or HFC, HFD or HFDU type fluid emulsions, in this case connected to an external source of pressure and flow rate.

[0155] In the return phase of the press, the pressure acting in the chamber 309 can advantageously be used to push the fluid with magnetorheological behaviour backwards, from the chamber 308 through the gap 310 to the cavity 350, up to the chamber 330, causing the piston 345 to descend and thus generating a reduction in volume of the chamber 340 and thus a flow rate of the third auxiliary fluid from this towards the actuator cylinders 150, causing the exit or return stroke of the respective shanks 151.

[0156] With reference to Figures 8 and 9, a fourth embodiment of the control unit in accordance with the invention is globally labelled 400.

[0157] For ease of reading, in this fourth example details similar to those in the third example will, unless otherwise indicated, be labelled with the reference number of the third example increased by 100. Thus, for example, the tubular body of the control unit, which in the third embodiment example is labelled 301, in the fourth embodiment example is labelled 401.

[0158] The control unit 400 differs principally from the control unit 300 of the previous example, in that the first separator element, indicated with 406, comprises a resilient membrane delimiting a closed volume, within which the second chamber 409 remains defined, and in that the second separator element, indicated with 445, also comprises a resilient membrane delimiting a closed volume, within which the fourth chamber 440 remains defined. In more detail, both membranes of the separators 406 and 445 are flexible and assume a respective substantially bag-like formation, as clearly illustrated in Figure 8.

[0159] Inside the bag defined by the separator 406 is the second compressible auxiliary fluid, e.g., a gas, preferably nitrogen, enclosed in the chamber 409, isolated therein or possibly connected with an external source, or an incompressible fluid such as hydraulic oil or HFC, HFD or HFDU type emulsions, in this case connected with an external pressure and flow source.

[0160] The third incompressible auxiliary fluid, such as hydraulic oil or HFC, HFD or HFDU type emulsions, is contained in the fourth chamber 440, defined by the separator bag 445. Said auxiliary fluid is also contained in the relative connection pipes between the fourth chamber 440 and the working chamber of the corresponding actuator 150.

[0161] The fourth chamber 440 is separated from the third chamber 430, in which the magnetorheological fluid is present, by the bag defined by the separator 445. Said bag thus allows the separation between the magnetorheological fluid and the third auxiliary fluid contained in the fourth chamber 440.

[0162] During the die working phase, the shanks 151 of the actuators 150 are pushed inside the respective cylindrical bodies 153, in this case filled with the corresponding third auxiliary fluid, generating an output flow from the openings 155 of each individual actuator 150 towards the control unit 400.

[0163] Such a flow rate of auxiliary fluid in input to the control unit 400 through the opening 413 (or several openings 413 if envisaged) results in an increase in the volume of the bag 445 or the volume of the chamber 440 with a consequent reduction in the volume of the chamber 430, communicating with the cavity 455 by means of the channels 450, which then generates a net flow rate of fluid with magneto-rheological behaviour through the calibrated passage gap 410 up to the chamber 408.

[0164] When the passage gap 410 is passed through by the fluid with magnetorheological behaviour (in the passage from the chamber 430 to the chamber 408 and vice versa), the gap being affected by the magnetic field generated by the passage of current in the electrical windings 415, a counterpressure is generated to the flow of the fluid with magnetorheological behaviour which produces the resistant force through the actuator devices 150, transmitted to the part of the die to which they are fixedly joined.

[0165] The flow rate of fluid with magnetorheological behaviour, having passed through the gap 410 flows into the chamber 408 leading to a consequent reduction in the volume of the bag 406 or the chamber 409. Such a change in volume is counteracted by the pressure acting in the chamber 409.

[0166] In the return phase of the press, the pressure acting in the chamber 409 can advantageously be used to push the fluid with magnetorheological behaviour backwards, from the chamber 408 through the gap 410 to the cavity 455, up to the chamber 430, causing the volume of the bag 445 to be reduced, viz., the volume of the chamber 440, and thus generating a flow rate of the third auxiliary fluid therefrom to the actuator cylinders 150, causing the exit or return stroke of the respective shanks 151.

[0167] It is understood that the operation described above for each example of control unit 100, 200, 300 and 400, considered in combination with actuator device 150, is fully analogous if said control units are operationally connected to the variant embodiment of the actuator device labelled with 150' above. It is also understood that each of the described examples of the control unit of the invention can be operationally connected to several actuator devices 150, 150' as described in detail above.

[0168] In the following, some of the features of the characteristics characterising the control unit of the invention are recalled, in each of the described embodiment examples.

[0169] Figures 15-17 depict an embodiment variant of the control unit 300 example described above. In this variant, globally labelled 300a, details similar to those of the control unit 300 are labelled, unless otherwise indicated, by the same numerical references.

[0170] This variant mainly differs from the control unit 300 in that the tubular body 301 extends axially between the opposite axial ends, defined by the head 303 and the base 302, surrounding both the zone of the chambers 308,309 and the zone of the chambers 330,340. Likewise, the tubular bush 305 also extends coaxially with the tubular body 301, affecting both the zone of the chambers 308,309 and the zone of the chambers 330,340.

[0171] 380 refers to a dividing septum, created internally in the bush 305, and made in a single piece with said bush, which separates a first internal space of the bush affected by the chambers 308,309 from a second internal space of the bush affected by the chambers 330,340.

[0172] The chambers 330, 340 are defined inside the axial cavity 348 of the body 347, said body 347 being surrounded externally by the tubular body 301, and for a main axial section thereof also being surrounded by the tubular bush 305.

[0173] The chamber 330 is in fluid connection with the first chamber 308 by means of an annular channel 390, which in turn is in communication with the passage 310 configured as a gap communicating with the first chamber 308.

[0174] The annular channel 390 surrounds an axial portion of the outer sheath of the body 347.

[0175] Thanks to the formation of this variant of the control unit 300, it is possible to make more compact and economical devices overall. Furthermore, the zone of the tubular bush affected by the electrical windings can be lengthened. The possibility of increasing the number of electrical windings 315 advantageously allows for a greater pressure drop with the same overall size of the control unit.

[0176] The operation of this variant is entirely similar to that of the control unit 300, and reference is therefore made to what was described above with reference to the control unit 300.

[0177] Figures 18-20 depict an embodiment variant of the control unit 400 example described above. In this variant, globally labelled 400a, details similar to those of the control unit 400 are labelled, unless otherwise indicated, by the same numerical references.

[0178] This variant mainly differs from the control unit 400 in that the tubular body 401 extends axially between the opposite axial ends, defined at the head 403 and the base 402, respectively, surrounding both the zone of the chambers 408,409 and the zone of the chambers 430,440. Likewise, the tubular bush 405 also extends coaxially with the tubular body 401, affecting both the zone of the chambers 408,409 and the zone of the chambers 430,440.

[0179] 480 refers to a dividing septum, created internally in the bush 405, and made in a single piece with said bush, which separates a first internal space of the bush affected by the chambers 408,409 from a second internal space of the bush affected by the chambers 430,440.

[0180] The chambers 430, 440 are defined inside an axial cavity of the body 447, said body 447 being surrounded externally by the tubular body 401, and for a main axial section thereof also being surrounded by the tubular bush 405.

[0181] The chamber 430 is in fluid connection with the first chamber 408 by means of an annular channel 490, which in turn is in communication with the passage 310 configured as a gap communicating with the first chamber 308. The annular channel 490 surrounds an axial portion of the outer sheath of the body 447.

[0182] Similarly to what has been described above, thanks to the formation of this variant of the control unit 400, it is possible to make more compact and economical devices overall. Furthermore, the zone of the tubular bush affected by the electrical windings can be lengthened 415. The possibility of increasing the number of electrical windings 415 advantageously allows for a greater pressure drop with the same overall size of the control unit.

[0183] The operation of this variant is entirely similar to that of the control unit 400, and reference is therefore made to what was described above with reference to the control unit 400.

[0184] With reference to the choice of incompressible auxiliary fluids, they can consist of a choice between hydraulic oil, HFC fluid (water and glycol), HFD or HFDU (water-free synthetic fluids), etc. The latter have greater conductivity and thermal capacity with respect to hydraulic oil, facilitating heat dissipation.

[0185] Among the various components, fluid-tight seals, such as oil scraper rings, o- rings, or others, are appropriately provided where required (in each embodiment of the control unit in accordance with the invention), and in themselves known.

[0186] The working chamber 154 (or 154' in the described embodiment variant) of the actuator and the cavities 111, 211, 311, 411, can be connected with a pressure transducer in order to perform closed-loop control of the pressure and thus the force exerted by the actuator cylinders.

[0187] The pressure modulation can be performed by appropriately modulating the magnetic field and thus the current in the windings 115, 215, 315 and 415. The pressure modulation as a function of the die stroke can be performed by reading an external position transducer, or, in the first and third embodiment examples, the position of the piston 106, 306, can advantageously be detected by means of a position transducer so as to indirectly control the position and speed of the actuator cylinders and regulate the reaction force exerted by them or the position and speed in the return stroke according to the desired logic.

[0188] The chambers 109, 209, 309, 409, configured to contain a compressible auxiliary fluid, e.g., nitrogen, can be isolated by caps or connected to a gas pressure regulation circuit and possibly to an additional gas vessel.

[0189] In the lower part of the body 153, 153' of the respective actuator 150, 150' or of the base 102, 202 or of the extension body 347, 447, pockets can be obtained for housing, for example, pressure and temperature sensors for monitoring such quantities in the magnetorheological fluid and connected to a circuit board. The circuit board itself can be housed in one of these pockets.

[0190] The actuator device and / or control unit can in fact be provided with such sensors (either one or both), connected to a control system. The respective figures for each embodiment example of the control unit show the bush 105, 205, 305, 405 with the respective windings 115, 215, 315, 415. It has, on the outer part, a series of circular grooves 116, 216, 316, 416, preferably parallel, and in which the respective electrical windings are housed. The distances between the grooves, thus between the windings, can be nonconstant, in order to optimise the effectiveness of the device (obtaining a uniform magnetic flux in the length of the gap). The thickness of the gap 110, 210, 310, 410 can also be variable to optimise the distribution of the magnetic flux along the corresponding bush.

[0191] The viscosity of the fluid with magnetorheological behaviour depends on the intensity of the electrical current, therefore the resistant force generated by the control unit can be modulated by varying the intensity of the current passing through the windings and thus the magnetic parameters, by means of the closed-loop control system (in feedback), depending on the parameters (pressure and temperature) measured by the sensors present on the base.

[0192] The windings can also be passed through by an electrical current during nonworking or set-up phases (possibly also modulating the current intensity) in order to heat the device and / or the magnetorheological fluid, avoiding working in critical temperature ranges for the viscosity of the fluid itself and avoiding transient phases due to changes in viscosity.

[0193] It is evident how, in all the embodiments, the possibility of acting instant by instant on the intensity of the electrical current passing through the windings allows to modify the viscosity of the magnetorheological fluid and thus the speed thereof through the gap, achieving an instantaneous control and modulation of the thrust and / or resistant force offered by the actuator shank during the stroke thereof.

[0194] The actuator device can therefore be controlled both actively, e.g., in the rising or return stroke of the actuator cylinder shank to perform a controlled extraction of a product from a die, controlling the rising speed, and semi- actively, e.g., to achieve a constant descent in the application to a blank holder.

[0195] Since there are windings on a fixed part of the control unit, viz., the bush, these do not imply technical complications (they make the connection with the power source easy) and the useful working length in which the fluid is magnetized is greater, with respect to the known devices, allowing higher forces to be applied, while at the same contributing to make the device compact.

[0196] The decision to integrate the compensation chamber 109, 209, 309, 409 in the respective control unit contributes to the compactness of the device and reduces the risk of leakage, as it does not require external connections (as would be the case with an internal compensator).

[0197] The thrust force can also be controlled and modulated when the shank of the actuator cylinders is in the raising or returning phase, benefiting operator safety.

[0198] In practice, it has been found that the invention achieves its intended task and aims, making a control unit of reduced size, capable of making the thrust force instantaneously modulable in the dependent actuators connected thereto, as well as the force, speed and position of the shank of such dependent actuators in the return or raising phase, also allowing, in the appropriate configurations, control of the movement of machine parts and avoiding harmful loads for the mechanical members and dangerous and damaging situations of instantaneous release of stored energy, while also overcoming the limitations of the known type of devices with magnetorheological fluid.

[0199] The invention thus achieves the proposed aims, achieving the stated advantages with respect to the aforementioned prior art.

Claims

CLAIMS1. A control unit (100; 200; 300; 300a; 400, 400a) for controlling an actuator device, the control unit comprising: a tubular body (101; 201; 301; 401) which defines an axial cavity (101a; 201a; 301a; 401a), the tubular body being closed at an end thereof by a base (102; 202; 302; 402) and, at the axially opposite end, by a head (103; 203, 303; 403), a tubular bush (105; 205; 305; 405) which is arranged internally with respect to the cavity and which is coaxial with the tubular body, a separator element (106; 206; 306; 406) which is arranged in the cavity and which is suitable for separating in a fluid-tight manner a first chamber (108; 208; 308; 408) from a second chamber (109; 209; 309; 409) which are defined in the tubular body, a passage (110; 210; 310; 410) being provided in the cavity between the tubular body (101; 201; 301; 401) and the bush (105; 205; 305; 405), the passage (110; 210; 310; 410) being in fluid connection with respect to the first chamber (108; 208; 308; 408), a first fluid with magnetorheological behaviour being provided in the first chamber (108; 208; 308; 408), a system of electrical windings (115; 215; 315; 415) which are provided in order to generate, when passed through by electrical current, a magnetization in the region of the passage (110; 210; 310; 410) to as to vary the flowing capacity of the first fluid through the passage and to generate a flow rate and / or a pressure in the first fluid suitable for controlling the movement of the actuator device and / or the forces acting on the actuator device when theactuator device is operationally connected to the control unit, there being provided in the second chamber (109; 209; 309; 409) a second fluid which is suitable for generating a pressure for acting counter to the pressure existing in the first chamber (108; 208; 308; 408) during the operational function of the control unit.

2. A control unit according to claim 1, wherein the tubular bush (105; 205; 305; 405) is fixedly joined to the tubular body (101; 201; 301; 401).

3. A control unit according to claim 1 or 2, wherein the passage (110; 210; 310; 410) comprises a gap having an axial section with an annular formation.

4. A control unit according to any one of the preceding claims, wherein the second fluid is a fluid of the compressible type.

5. A control unit according to any one of the preceding claims, wherein the second fluid is an inert gas.

6. A control unit according to any one of the preceding claims, wherein the separator element (106; 306) comprises a piston which is slidingly mounted inside the tubular bush (105; 305) in a fluid-tight manner.

7. A control unit according to any one of claims 1 to 6, wherein the separator element (206; 406) comprises a resilient membrane which delimits a closed volume and the second chamber (209; 409) is defined in the volume.

8. A control unit according to any one of claims 1 to 7, wherein the passage (110; 210) is in communication with an opening (113; 213) of the unit which is outwardly open and through which the first fluid is made available for controlling an actuator device when it is operationally connected to the control unit.

9. A control unit according to any one of claims 1 to 7, comprising a thirdchamber (330; 430) and a fourth chamber (340; 440) and a second separator element (345; 445) which is suitable for separating the third chamber (330; 430) from the fourth chamber (340; 440) in a fluid-tight manner, the third chamber (330; 430) being in fluid connection with respect to the first chamber (308; 408) by means of a connection channel (350; 390; 450; 490) for the passage (310; 410) with respect to the third chamber (330; 430), there being provided in the fourth chamber (340; 440) a third fluid which is intended to supply an actuator device when the actuator device is operationally connected to the control unit.

10. A control unit according to claim 9, wherein the second separator element (345) comprises a respective second piston which is slidingly mounted in the unit in a fluid-tight manner.

11. A control unit according to claim 10, wherein the second piston (345) is slidingly engaged in a fluid-tight manner in an extension body (347) of the unit which is fixedly joined to the base.

12. A control unit according to claim 9, wherein the second separator element (445) comprises a respective second resilient membrane which delimits a closed volume and the fourth chamber (340; 440) is defined in the volume.

13. A control unit according to any one of claims 9 to 12, wherein the fourth chamber (340; 440) is in communication with an opening (313; 413) of the unit which is outwardly open and through which the third fluid is made available for controlling the actuator device when it is operationally connected to the control unit.

14. A combination of at least one actuator device (150; 150') and a control unit (100; 200; 300; 300a; 400, 400a) for the device, comprising an actuatordevice with a single-action hydraulic cylinder and a control unit according to any one of the preceding claims.

15. A combination according to claim 14, wherein the actuator device (150; 150') is configured as a linear actuator.

16. A combination of an actuator device (150; 150') and a control unit (100; 200) for the device, comprising an actuator device with a single-action hydraulic cylinder and a control unit according to claim 8, the actuator device comprising a piston with an actuator shank (151; 151'), the piston delimiting an operating chamber (154; 154') which is configured to be connected, with fluid connection, by means of a pipe, to the opening (113; 213) of the control unit so that the operating chamber (154; 154') is supplied with the first fluid.

17. A combination of an actuator device (150; 150') and a control unit (300; 300a; 400; 400a) for the device, comprising an actuator device with a singleaction hydraulic cylinder and a control unit according to claim 13, the actuator device comprising a piston with an actuator shank (150; 150'), the piston delimiting an operating chamber (154; 154') which is configured to be connected, with fluid connection, by means of a pipe, to the opening (313; 413) of the control unit so that the operating chamber (154; 154') is supplied with the third fluid.

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