Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B7/00—Systems in which the movement produced is definitely related to the output of a volumetric pump; Telemotors
  • F15B7/001—With multiple inputs, e.g. for dual control
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B21/00—Common features of fluid actuator systems; Fluid-pressure actuator systems or details thereof, not covered by any other group of this subclass
  • F15B21/06—Use of special fluids, e.g. liquid metal; Special adaptations of fluid-pressure systems, or control of elements therefor, to the use of such fluids
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B7/00—Systems in which the movement produced is definitely related to the output of a volumetric pump; Telemotors
  • F15B7/005—With rotary or crank input

Definitions

• the present invention relates to positioning cylinders with three axes, capable of supporting objects having masses up to several hundred tonnes, while allowing their positioning with an accuracy of the order of a micrometer. It also relates to servo-control methods using these jacks.
• actuators are used arranged between this seat and the structure. These jacks are adjusted manually or electrically by agents who will carry out iterative adjustment operations, until the desired position is reached. In practice, however, it is extremely difficult, if not impossible, to obtain great precision in such a context.
• actuators are usually used as actuator, the two best known principles of which are:
• a piston In a hydraulic cylinder, a piston, provided with a seal, is free to move in the base of the cylinder, the chamber of which is completely filled with a liquid, very weakly compressible.
• the piston moves, either because the volume of liquid in the chamber is modified by injection or evacuation of the liquid via a conduit, a pump, a shut-off valve and a reservoir, either because an action piston, also provided with a seal, actuated for example by a screw / nut assembly changes the shape of the chamber.
• the liquid being almost incompressible, the piston moves so that the volume of the chamber remains practically constant.
• a force multiplier device comprising a first hydraulic cylinder, the piston rod of which is slidably mounted in an enclosure integral with the base of this cylinder and constituting the chamber of a second cylinder also equipped with a sliding piston subjected to the action of an elastomer confined in this chamber and transmitting pressures in a hydrostatic manner.
• a transmission and / or pressure device comprising a main piston actuated by a rod subjected to pressure.
• This piston acts on an elastomer mass confined in a chamber and which ensures pressure transmission to two action pistons.
• These action pistons are controlled in movement by piezoelectric actuators.
• These force multiplier devices use as working fluid a mass of elastomer. They cannot however ensure the function of a positioning cylinder offering the precision required here.
• the first actuator or actuator is a hydraulic actuator, which would make it difficult to find high precision.
• the transmission device disclosed in document DE 3,916,539 is not a force multiplier and cannot be used as a positioning cylinder since its main piston has a cross section smaller than that of the action pistons controlled by the piezoelectric actuators and one then obtains small strokes at the level of the action pistons and a large stroke of the main piston, which could not allow the required level of precision to be obtained.
• the object of the present invention is to remedy these drawbacks by proposing a three-axis positioning cylinder which provides high positioning precision while being less costly and more reliable to produce than current cylinders.
• a positioning cylinder with three axes including at least one motorized axis comprising: - a base comprising mobile support means and means for vertically moving these mobile support means, and - an axis ensuring a connection between the movable head of said cylinder and the base.
• the connecting axis is designed to produce a double ball joint type allowing lateral movement of the head relative to the base, and the mobile support means comprise a mass of elastomer against which the end lower of the connecting axis is in support.
• Such a jack allows, thanks to the double ball joint type, three-dimensional positioning more precise than what can be expected from current actuator techniques.
• the use of a part made of elastomeric material provides force transmission and damping functions which are particularly appreciated in the position control of heavy structures.
• the part made of elastomeric material can advantageously be used as working fluid.
• a positioning cylinder with three axes is proposed, at least one of which is a motorized axis, comprising:
• a base comprising a bore containing a chamber in which a working fluid is confined and an axis ensuring a connection between the head of the jack and the base;
• the mass of solid elastomer which behaves under load like a quasi-fluid, is deformed by an action piston which is motorized.
• This deformation has the effect of displacing the working piston so that the volume of the chamber remains constant.
• a three-axis positioning cylinder characterized in that the movable support means comprise a movable part for receiving the elastomer part acting as a ball joint, this part movable being slidably mounted relative to the base and actuated by means of micrometric ball screws.
• This cylinder preferably further comprises a second piece of elastomer acting as a ball joint between the upper end of the connecting axis and the movable head.
• the cylinders according to the invention are compact and compact. Furthermore, they are easy to produce and therefore economical, their operation is safe since there is no longer any risk of a seal rupture.
• the jacks according to the invention coupled to servo means, the jacks according to the invention allowing very precise positioning, due to a high positioning resolution.
• actuators which are particularly effective for positioning a heavy structure relative to a absolute reference or of several structures between them, with a high level of precision, since by combining several three-axis cylinders according to the invention (for example three three-axis cylinders including two motorized axes), it is possible to control the six degrees freedom of an object.
• a positioning cylinder with three axes, two motorized axes one of which is vertical and the other planimetric, the remaining axis being free or guided, -
• a positioning cylinder with three axes one of which is a motorized vertical axis, the other two planimetric axes being free or guided.
• a positioning cylinder with three axes, two motorized axes of which may further comprise a motorized stop to provide lateral movement of the head of the cylinder along a first horizontal axis.
• This motorized stop comprises for example an action screw driven by a geared motor.
• the positioning cylinders with three axes according to the invention can advantageously be controlled in position relative to an absolute reference, along at least one of said motorized axes.
• additional action pistons can be distributed on the periphery of the chamber to increase or preset the stroke of the jack; these action pistons are then actuated by a motorized or manual screw-nut system; - a mechanical preload system (by spring) of the elastomer can be provided for uses under very low loads;
• a displacement sensor can be associated with the cylinder for the slave versions.
• All these embodiments can be associated with displacement sensors, allowing relative control of these jacks.
• a method for controlling the position of a structure supported by positioning cylinders according to the invention comprising measurements of the position of this structure and a control of each controlled cylinder from these measurements and position instructions.
• N cylinders according to the invention with a slave axis, to act on a deformable solid and define the geometry thereof, for example for servo-leveling or servo-alignment of large machines or long tubes, or to correct the shape of a large deformable solid, or to achieve the flatness of a frame of a large machine tool or the straightness of the translation of a large mass.
• Servos of N cylinders according to the invention by as many sensors measuring with respect to one or more absolute references also fall within the scope of the present invention.
• FIG. 1 shows in section an embodiment of a cylinder with three axes including two motorized axes according to the invention
• - Figure 2 is a top view in section of the cylinder shown in Figure 1
• - Figure 3 is a sectional view of an embodiment of a three-axis cylinder including a motorized axis according to the invention
• FIG. 4 is a top view in section of the upper part of the cylinder shown in Figure 3;
• FIG. 5 shows in section a first example of another embodiment of a three-axis cylinder according to the invention.
• FIG. 6 shows in section a second example of this other embodiment of a three-axis cylinder according to the invention.
• FIG. 7 illustrates an example of implementation of three cylinders according to the invention to control the six degrees of freedom of a structure
• - Figure 8 shows a first combination of sensors used to provide a spatial position relative to absolute reference frames of a non-deformable structure
• FIG. 9 shows a second combination of sensors used to provide a spatial position of a structure in the control process
• FIG. 10 shows a third combination of sensors used to provide a spatial position of a structure in the control method according to the invention.
• FIGS. 1 to 6 illustrates an exemplary implementation of a set of cylinders according to the invention for the alignment of long tubes.
• These jacks are particularly suitable when it comes to positioning and controlling an object in space. Indeed, to position and maintain an object in space, it is necessary to manage its six axes of freedom. These axes are generally controlled by three actuators which manage the different axes and support the mass of the object to be positioned.
• the traditionally used solution uses three cylinders oriented along the vertical axis Z which manage and control this vertical axis by simultaneous movements, and the rotations in the horizontal plane Ox and Oy by differential movement.
• a table with crossed movements arranged under one of the jacks manages the horizontal displacements of the axes X and Y.
• a third simple translation arranged under one of the two other jacks and oriented along the Y axis is still necessary to manage the last axis Z.
• the base 41 of the jack 40 of the invention includes a bore 410 which receives a first wafer of one elastomer 2 and a piston 43 in form of a double ball joint type of bone whose lower end is bearing against the pad 2.
• the jack further comprises a movable head 45 comprising a bore 456 containing a second elastomer pad 455 against which the upper end of the piston 43 bears, and a peripheral cylindrical part 450.
• the vertical movement Z is obtained by the action of action pistons 44, on the elastomer 2, manually adjustable action pistons 44 ensuring the initial positioning adjustment, and at least one action piston 4 being motorized for servo-control in position.
• the geometry of the piston allows the rotations around the axes X and Y which then generate translations respectively on the axis X and the axis Y of the head of the jack 40.
• the elastomer pad 455 is confined in the second chamber, the shape of which is modified by the displacement of two action pistons 451, 452 manually controlled by adjustment screws 453, 454.
• the motorization on the horizontal axis X is produced by means of a motorized stop bearing against the external periphery 42 of the base 41 is actuated by a geared motor 48 for control on the axis in question, comprising:
• a counter-stop 461 which provides guidance on the axis considered X and the adjustment of the operating clearance
• This jack 60 has a bore 410 receiving an elastomer pad 2 and a piston 63 whose base of ball-and-socket type rests on the elastomer pad 2 and whose end upper comprises a housing 433 arranged to receive a ball 431 ensuring the second function of ball joint, the upper part 65 also comprising a suitable housing 432 for receiving this ball.
• the ball joints are made of elastomeric material and the following displacement of the connecting axis is ensured by a micrometric ball screw device, with reference to the examples of embodiment shown in Figures 5 and 6 in which the common elements have common references.
• the actuator 50 comprises a base 51 provided with a cylindrical upper part 52 comprising a bore 521 in which slides a movable part 550 whose positioning is controlled by a micrometric ball screw device 510.
• the movable part 550 is designed to receive a first piece 554 of elastomeric material in which is housed a lower end 532 of a piston 53 in the form of a bone of double ball type.
• the upper end 531 of the piston 53 is housed in a second piece 555 of material elastomer embedded in a bore 556 of a movable head 55 of the jack 50.
• the vertical movement in Z of the movable head 55 is obtained by action on the micrometric ball screw device 510 which can be actuated by a stepping motor.
• the two elastomer pieces 554, 555 provide both a ball joint and damping function.
• the geometry of the piston 53 authorizes the rotations around the axes X and y which then generate translations respectively on the axis X and the axis Y of the head of the jack 50.
• the motorization on the horizontal axis X is produced by means of a motorized stop bearing against the external periphery of the upper part 52 of the base 51 is actuated by a geared motor 58 for control on the axis in question, and comprising:
• a counter-stop 561 which provides guidance on the axis considered X and the adjustment of the operating clearance
• the gear motor 58 is fixed to the peripheral cylindrical part 551 of the head 55 of the jack 50 by fixing means 59.
• the action screw 56 is moved in translation by a motorized nut 57 driven by the shaft of the gear motor 58.
• the second horizontal axis Y is simply blocked by means of screw-stops.
• the piston 33 of the cylinder 30 has respectively substantially lower and upper ends 332, 331 which come into abutment respectively against a first and a second part 354, 355 made of elastomeric material.
• These first and second parts 354, 355, which for example have the shape of cylindrical pellets, are housed respectively at inside the sliding movable part 550 and in the bore 556 formed inside the movable head 55.
• control method according to the invention can for example be implemented to maintain the geometry of a deformable structure.
• the use of N cylinders with a motorized axis controlled by reference to absolute external references then makes it possible to compensate for the movements of the ground, mechanical stresses, etc., for example for the alignment of a long tube or the leveling of a machine tool.
• FIG. 11 which represents a system for aligning a long tube
• the absolute reference is defined by a stretched wire F.
• a long tube 111 rests on a first set of cylinders VI-V6 according to the invention arranged along the axis Z to be corrected, while a second set of cylinders V'l-V'6 according to the invention is arranged along the tube 111 and along the horizontal axis X.
• a set of biaxial distanceometers E1-E6 makes it possible to carry out biaxial deviation measurements with respect to this wire to correct the alignment of the tube 111.
• the coordinate system in a second configuration, can be defined by a body of water defining a horizontality. In a third configuration, the coordinate system can be defined by one or two axis clinometers.
• Three-axis cylinders according to the invention can, for example, be used to control the spatial position of two or N non-deformable structures 80.
• the six degrees of freedom are checked non-deformable structures 80 each supported by three positioning cylinders with three axes 81, 82, 83 according to the invention arranged on the ground 84, to each of these positioning cylinders 81, 82, 83 being assigned a vertical movement axis A1, A2, A3 and a movement axis lateral A5, A4, A6.
• Each positioning cylinder 81, 82, 83 according to the invention is provided with a first geared motor 812, 822, 832 to drive an action piston controlling the vertical movement Z and the tilts ⁇ x, ⁇ y of the structure.
• Two positioning cylinders 81, 82 are further provided with a second geared motor 818, 828 to drive a motorized stop controlling the movement Y and ⁇ z of the structure.
• the third positioning cylinder 83 is provided with a manually adjustable stop controlling the movement along the horizontal axis X.
• This servo-control method comprises a detection of the spatial position of each structure 80 relative to an absolute coordinate system R, and a closed-loop control command of the three positioning cylinders 81, 82, 83 on this coordinate system.
• the absolute coordinate system is defined by two tensioned wires and the position measurements include:
• the absolute coordinate system is defined by two tensioned wires and the position measurements include: a uniaxial deviation measurement EcZ along a vertical axis Z, relative to a first tensioned wire FI along a first horizontal axis X,
• the position measurements comprise: a measurement of altitude AL carried out at a first point of the structure 80 along a vertical axis Z,
• the position measurements are for example carried out at the level of the positioning cylinders, but may very well be carried out at other points of the structure.
• Each positioning cylinder 81, 82, 83 is associated with a measurement along the vertical axis Z, and two of said positioning cylinders 81, 82 are associated with the two measurements along the second horizontal axis Y.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Actuator (AREA)
• Machine Tool Units (AREA)

Applications Claiming Priority (3)

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• 1995
  • 1995-12-08 FR FR9514529A patent/FR2742209B1/fr not_active Expired - Fee Related
• 1996
  • 1996-12-06 WO PCT/FR1996/001955 patent/WO1997021929A1/fr not_active Application Discontinuation
  • 1996-12-06 EP EP96941718A patent/EP0862696A1/de not_active Ceased
  • 1996-12-06 US US09/077,788 patent/US6186480B1/en not_active Expired - Fee Related
  • 1996-12-06 JP JP09521788A patent/JP2000501686A/ja not_active Ceased

Non-Patent Citations (1)

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