Machine tool

Abstract

The invention relates to a machine tool (M) comprising a frame (100) and at least one positioning module (P) for positioning a rotary work spindle (200), the positioning module (P) moving the rotary work spindle (200) relative to the fixed frame (100) by way of a plurality of links. The machine tool is characterised in that the pivot links on multiple axes are each implemented by two bearings. The axes of the different links and the elements implementing said links are arranged in a specifically designed manner, the masses of the different components being substantially defined and distributed in such a way that the reduction gears of the motors of the first and second pivot links are preloaded by virtue of the resulting overhang. Each axis of the pivot links comprises two measurement systems, wherein the position measurement feedback from the closed loop servo is provided by a position encoder arranged after the reduction gear, while the encoder arranged before the reduction gear regulates the speed.

Description

Description Title of the invention: MACHINE TOOL

[0001] FIELD OF APPLICATION OF THE INVENTION

[0002] The present invention relates to the field of machine tools, particularly machining tools, and more particularly to adaptations of the kinematic structures of machine tools used for operations requiring high rigidity.

[0003] DESCRIPTION OF THE PRIOR ART

[0004] Among the articulated structures that can be used to move a spindle carrying a machining tool, there are articulated structures called articulated arms, which are very well known in the field of robotics,

[0005] While offering many advantages, these structures nevertheless have the disadvantage of not having the rigidity and precision required for certain machining operations. Thus, for example, document CN110802465 proposes automatic deburring equipment with seven axes of movement whose rigidity and precision performance do not allow for machining operations of prismatic parts within the tolerances and qualities required by these parts.

[0006] To resolve them, the applicant has imagined the structure proposed in document EP3487667 which describes a machining machine tool comprising a kinematic structure setting an electro-spindle in motion along a plane perpendicular to the axis of the electro-spindle and remarkable in that said kinematic structure is an articulated structure comprising two arms articulated relative to a plate along axes of rotation parallel to the axis of the electro-spindle, the second end of the second arm receiving the electro-spindle, the translation of the part to be machined towards the tool of the electro-spindle according to a linear movement parallel to the axis of the electro-spindle being ensured by a part support module or by a plate support module,

[0007] ] This machine tool architecture is particularly advantageous in that it offers an articulated two-arm structure to implement the movements of the electro-spindle along the plane perpendicular to the axis of rotation. of the electro-spindle. An articulated structure formed by two pivoting arms is simpler and less expensive to implement than conventional stacked structures.

[0008] The only movement along a linear axis is that implemented except for the relative translation between the part and the tool parallel to the axis of the electro-spindle, which corresponds to the so-called plunge movement.

[0009] This plunge movement is implemented either by a movement module associated with the part holder module, and then the plate is fixed in translation, or by a movement module associated with the plate and then the part is fixed in translation except for machining.

[0010] The invention thus constituted the result not only of a reduction in the number of movement axes of the multi-axis articulated robot-type structures but also of a selection and distribution between positioning axes implemented by the articulated structure and a working axis implemented by the translational movement. The proposed kinematic structure therefore did not present redundant movements.

[0011] Reducing the number of movement axes made it possible to save on the associated movement means and to reduce positioning uncertainty.

[0012] It was not the articulated structure that carried out the axial machining forces (drilling, tapping, etc.), but the axis under the part or the plate.

[0013] The use of an articulated structure also made it possible to enlarge the window in which machining can be carried out. In addition, an articulated structure can carry out movements outside of said window and makes it easier to carry out a plurality of operations such as:

[0014] tool change,

[0015] maintenance,

[0016] carrying out machining in a different area,

[0017] the withdrawal clearance of the machining unit in order to load or unload a bulky part,

[0018] etc...

[0019] This machine tool configuration is open and has a larger access area, which provides great flexibility in:

[0020] the positioning of the tool magazine,

[0021] tool magazine integration,

[0022] the positioning of the tool change point,

[0023] the choice of how to change tools,

[0024] the positioning of the turntable,

[0025] the juxtaposition of several machine tools in accordance with the invention,

[0026] the possibilities of accommodating a robotic trolley capable of operating in the machining area or as close as possible to it and carrying tools enabling different functions to be carried out.

[0027] Such a configuration made it possible to define new zones while the electro-spindle of a conventional machine tool moves conventionally within its machining zone. The articulated structure of the machine tool of the invention allowed the electro-spindle to go beyond or outside the machining zone.

[0028] This selection in joints and strokes nevertheless limits the use and therefore the commercial exploitation of such a machine tool.

[0029] Another document EP3310528 describes a machine tool for machining a workpiece, comprising a spindle arm having a spindle for receiving a tool or the workpiece, the spindle arm being movably attached to a spindle arm receiving portion arranged on a machine frame; wherein the spindle arm comprises; a first spindle arm section, which is designed as a longitudinal member and can be rotated about a first axis of rotation relative to the spindle arm receiving section and is hinged to the spindle arm receiving section; a second spindle arm section, designed as a longitudinal member and rotatable relative to the first spindle arm section about a second axis of rotation, which is connected to the first spindle arm section; the spindle arm receiving section comprising: a first subsection and a second subsection spaced apart on the machine frame for receiving the spindle arm, the first subsection of the spindle arm receiving section having a first drive biased to transmit a first torque to the first spindle arm section; wherein the first spindle arm section comprises: a first subsection and a second subsection spaced apart on the spindle arm receiving section for receiving the second spindle arm section, the first subsection of the first spindle arm section having a second drive for transmitting a second torque to the second spindle arm section.

[0030] This document does not describe how the rigidity and precision required for the quality of certain machining operations can be achieved. As with the previous document, it is known that the use of double bearings for each pivot connection contributes to this objective. However, the described search for torque transmission may contravene the achievement of the rigidity necessary to obtain the desired precision.

[0031] Furthermore, as with the previous document, the number of articulation axes and movements is limited.

[0032] Another document EP3290163 describes a machine tool for machining a workpiece and a spindle holder assembly for use on such a machine tool.The machine tool comprises a machine frame, a clamping section arranged on the machine frame for clamping a workpiece on the machine tool, a pivot arm receiving section arranged on the machine frame, a first pivot arm pivotally mounted on the receiving section so as to be pivotable about a first axis of rotation, a second pivot arm pivotally mounted about a second axis of rotation, a spindle support arm mounted on the second pivot arm so that it can rotate about a third axis of rotation, a milling head mounted on the spindle support arm so that it can rotate about a fourth axis of rotation, and a work spindle held on the milling head for receiving a tool, the third axis of rotation being oriented perpendicular or transverse to the fourth axis of rotation.

[0033] Although less limited in its movement possibilities, it appears that the arrangement of the different sub-assemblies of this machine tool and their dimensioning lead to an unbalanced structure that is less rigid and less precise than what could be obtained and therefore not usable for the economic realization of certain machining operations.

[0034] BRIEF DESCRIPTION OF THE INVENTION

[0035] The applicant has carried out research aimed at proposing a machine tool, in particular a machining tool with an articulated arm, presenting optimized characteristics.

[0036] The machine tool of the invention comprises a frame and at least one module for positioning a rotating work spindle, said positioning module ensuring the movement of the rotating work spindle relative to the fixed frame by implementing the following connections;

[0037] - a sliding connection for horizontal translational movement along a first axis of a carriage relative to the frame,

[0038] - a first pivot connection for a rotational movement along a second axis parallel to the first of a first arm relative to the carriage,

[0039] - a second pivot connection for a rotational movement along a third axis parallel to the first two of a second arm relative to the first arm,

[0040] - a third pivot connection for a rotational movement along a fourth axis included in a plane perpendicular to the first three axes,

[0041] - a fourth pivot connection for a rotational movement of a rotating work spindle support along a fifth axis perpendicular to the fourth axis,

[0042] the implementation of the pivot links along the fourth axis and the fifth axis being carried out by a sub-assembly called the wrist,

[0043] the rotating work spindle ensuring the rotational movement of a tool along a sixth axis perpendicular to the fifth axis.

[0044] This machine tool is remarkable in that the pivot connections on the second axis, the third axis and the fifth axis are implemented by two bearings each: a main bearing and a secondary recovery bearing distant from each other,

[0045] the fourth axis of the third pivot link is positioned in a median plane defined between the two bearings guiding the rotation of the pivot link along the third axis,

[0046] these pivot connections each being the subject of a motorization integrating a geared motor composed of a motor and a reducer,

[0047] the masses of the different components being defined and distributed so that due to the overhang formed, the reducers of the motors of the first and second pivot links are preloaded,

[0048] the machine tool being controlled by a control unit associated for each axis of the pivot links, with a variator to process servo loops operating in a closed loop,

[0049] each axis of the pivot links comprising two measuring systems with a first encoder arranged before the reducer ensuring speed measurement for speed regulation purposes and a second encoder arranged after the reducer ensuring position measurement for the closed loop of a position control,

[0050] said position measurement feedback from the encoder placed after the reducer being made at the variator level,

[0051] the sixth axis of rotation of the tool moving in a plane of movement passing through the fourth axis of the third pivot link.

[0052] These characteristics are implemented in association with a dimensioning of the different subassemblies guaranteeing a high rigidity. To achieve this objective, according to a characteristic of the invention, the different subassemblies are dimensioned to achieve a static stiffness greater than 10 N / μm (static stiffness of maintenance between the rotating work spindle and the frame). For information, the static stiffness of a robot comprising an articulated serial kinematics is less than 1 N / μm.

[0053] So,

[0054] this mechanical dimensioning,

[0055] the recovery bearings on the second, third and fifth rotary axes,

[0056] the two axis measuring systems,

[0057] the combination of the linear axis, the two articulated arms, carrying two rotary axes forming a wrist,

[0058] which allow:

[0059] a reduction in arm length,

[0060] maximum stiffness of the geared motors thanks to the preload provided by the weight of the equipment mounted cantilevered in the work area;

[0061] provide dynamics to the transmission between the motor and the moving parts on the second and third axes such that position regulation can be ensured with position feedback measured by a second encoder, directly and only on the moving part after the reducer, while providing a stability margin which allows a position gain high enough to achieve optimum trajectory tracking.

[0062] Such a design allows, at the level of the rotating work spindle, to achieve:

[0063] a static stiffness greater than 10 N / pm in the accessible working volume between the tool and the frame,

[0064] improved quality of work,

[0065] improved positioning accuracy,

[0066] Improved drilling and milling capabilities in aluminum.

[0067] Such a machine tool design also makes it possible to achieve a high jerk (derivative of the acceleration vector with respect to time - i.e. the third derivative with respect to time of the position vector) on the positioning trajectory, namely 100 m / s 3 .

[0068] The integration of the second encoder into the positioning loop, associated with a high jerk, is made possible by the high stiffness obtained by the structure, imperative characteristic to achieve high quality and precision for the operation to be carried out.

[0069] The high kinematic stiffness makes it possible to position the encoder of the position control loop on the moving part after the reducer. The orientation of the arms in the working area is designed to generate a preload on the reducer associated with the first pivot connection that is all the greater, and thus increase its rigidity, as the inertia related to the axis is high. This has the effect of maintaining a constant and high ratio between rigidity and inertia, which ensures optimal performance of the position control throughout the working area. Indeed, thanks to this rigidity, a sufficiently high natural frequency is obtained on the first pivot connection, which allows position regulation on the second encoder and more dynamic behavior.

[0070] In fact, the position information from the second encoder returns directly to the drive for regulation purposes (and not to the digital control) in the position control loop.

[0071] In addition, these performances allow to get as close as possible to the theoretical model or transform that can be calculated by the mathematical tool or software integrated in the control unit of the machine tool. The use of this transform of the numerical control allows to simplify / eliminate the mechanical adjustments of the geometries of the different axes,

[0072] According to a preferred embodiment, the first encoder provides a measurement of speed only.

[0073] According to another particularly advantageous characteristic of the invention, the machine tool comprises cables and pipes for supplying the necessary energy to the rotating work spindle, the second arm and the wrist being provided with a hollow core in order to accommodate them.

[0074] This feature protects cables and hoses from contamination by chips or cutting fluid and limits the risk of interference with the workpiece holder assembly and / or the workpiece.

[0075] According to another particularly advantageous characteristic of the invention, the machine tool comprises on the fourth axis and the fifth axis of rotation, means for winding the cables and pipes preventing them from twisting during movements so that they only work in flexion, thus improving their durability.

[0076] According to another particularly advantageous characteristic of the invention, the subassembly called wrist forms an assembly with the rotating work spindle, an assembly which, comprising the motors and reducers associated with the fourth, fifth and sixth axes, is introduced and fixed in the second arm by means of an interface flange so that said assembly can be easily mounted, dismounted and extracted from the rest of the machine, reducing the duration of maintenance operations.

[0077] This wrist function also includes the cables and pipes supplying energy from the cable chain of the mobile trolley in translation along the first axis.

[0078] This second arm is of sufficient section to contain the cable winding system and allow the diameter of said cable windings to be changed.

[0079] According to another particularly advantageous characteristic of the invention, the hollow core of the second arm accommodates a winding shaft and a concentric jacket defining a winding volume of a single sheath grouping together cables and pipes, the radius of curvature of the cables and pipes in the winding volume evolving according to the angle of rotation of the wrist along the fourth axis.

[0080] According to another particularly advantageous characteristic of the invention, the wrist subassembly is equipped with two bearings to implement the pivot connection along the fifth axis and between which the rotating work spindle rotates, a first bearing accommodating a geared motor crossed axially by a rotating joint, for the supply of hydraulic and pneumatic energy to the rotating work spindle.

[0081] As the machine tool of the invention is a machine tool, particularly for machining, the hydraulic cables used are high pressure cables.

[0082] According to another particularly advantageous characteristic of the invention, the second bearing of the wrist subassembly guides in rotation a rotating part secured to the rotating work spindle and equipped with a winding device for the cables and pipes necessary for the supply of electrical energy and for lubrication so that the radius of curvature of said cables and pipes varies according to the angular position of the rotating work spindle along the fifth axis,

[0083] According to another particularly advantageous characteristic of the invention, the first arm comprises between the second axis and the third axis of rotation a concave volume allowing an increased angular travel of the second arm which can be housed in this concavity in the folded position. This design provides great compactness to the positioning module in the folded position, thus freeing up the space available for loading / unloading / transferring parts and optimizing the footprint of the machine (reduced floor space occupied).

[0084] According to another particularly advantageous characteristic of the invention, said first arm comprises two ends, a first end crossed by the second axis of rotation and a second end crossed by the third axis of rotation, the concave volume starting from the lower end and being defined so that in the folded position, this concave volume prevents the rear part of the rotating work spindle from hitting against the first arm.

[0085] The rotating spindle can project backwards relative to the fifth axis of rotation without rotation along this axis being hindered in the folded position.

[0086] According to another particularly advantageous characteristic of the invention, the bearings supporting the second axis and the third axis are symmetrical. This design allows the geared motors of these axes to be installed either on the right or on the left. It has the advantage of reducing the space requirement on one of the side faces of the positioning module. It is thus possible to choose the versions of the positioning modules (reduced space requirement on one or other of the side faces) according to the machine's installation constraints. This advantage is particularly interesting in a machine tool configuration with two working units, sharing the same slide. It allows for a minimal distance on the first axis between the two units, thanks to the "external" installation of the geared motors.

[0087] This symmetrical design can also allow the integration of an additional motor or a balancing system opposite the main motor of the axis, with the aim of increasing machining capacities, reducing energy consumption or increasing the lifespan of components (such as reducers).

[0088] According to another particularly advantageous characteristic of the invention, the second arm is preformed so that the fourth axis of rotation intersects perpendicularly with the fifth axis of rotation and does not intersect with the third axis of rotation. By moving the fourth axis outward from the third, the size of the positioning module in the folded position is optimized. By moving the fourth axis away, the rigidity of the two arms is improved by avoiding too large a recess in the first arm while keeping a second arm of large dimensions to integrate the cable winding system.

[0089] According to another particularly advantageous characteristic of the invention, said first arm comprises two ends, a first end crossed by the second axis of rotation and a second end crossed by the third axis of rotation, said second end being equipped with two bearings to guide the second arm in rotation along the third axis,

[0090] said second arm comprises two ends, a first end crossed by the third axis of rotation and a second end receiving the subassembly called wrist,

[0091] the first end of the second arm being preformed to be accommodated between the two bearings equipping the second end of the first arm.

[0092] According to another particularly advantageous characteristic of the invention, said first arm comprises two ends, a first end crossed by the second axis of rotation and a second end crossed by the third axis of rotation,

[0093] said second arm comprises two ends, a first end crossed by the third axis of rotation and a second end receiving the subassembly called wrist,

[0094] the first end of the second arm being equipped with two bearings for guiding the second arm in rotation along the third axis, said two bearings being spaced apart so as to come on either side of the second end of the first arm.

[0095] This latter configuration makes it easier to envisage the following characteristic, namely that the second end of the first arm crossed by the third axis of rotation is equipped with two bearings to guide the second arm in rotation along the third axis, the geared motor being arranged between the two bearings of the second end of the first arm.

[0096] The arrangement between the bearings of the geared motor provides greater compactness because the latter does not protrude beyond the volume of the articulated structure. In addition, the geared motor is better protected.

[0097] According to another particularly advantageous characteristic of the invention, the translation along the first axis is motorized according to one of the following technologies:

[0098] - by means of a linear motor,

[0099] - by means of a ball screw motor,

[0100] - by means of a rack.

[0101] The preferred combination of geared motors for rotary axes and a linear motor for the translation axis:

[0102] -allows a very large and modular stroke on the first axis

[0103] - allows work on very long pieces

[0104] - Provides the possibility of integrating several work modules to work on the same long piece and / or on several separate workstations.

[0105] According to another particularly advantageous characteristic of the invention, said frame is preformed so as to accommodate two horizontal rails arranged parallel to the first axis of translational movement and offset in height, said carriage being preformed to cooperate with said rails.

[0106] According to another particularly advantageous characteristic of the invention, the translation along the first axis is motorized by means of a linear motor and said frame comprises a vertical flat surface with a longitudinal axis parallel to the rails and intended to accommodate the secondary part of the linear motor, said flat surface being arranged higher than said rails and offset laterally,

[0107] said carriage being preformed to accommodate the primary part of the linear motor.

[0108] According to another particularly advantageous characteristic of the invention, the frame accommodates guide and motorization elements along the first axis and is designed in juxtaposable and removable length units so as to

[0109] - facilitate transport,

[0110] - reduce transport costs,

[0111] - be adaptable according to the needs of customers or the pieces to be worked on.

[0112] The position of the workpiece support relative to the frame is configurable.

[0113] In addition, the geometry of the frame channels the chips / effluents in the front part, facilitating their extraction.

[0114] The positioning of the rails, the motor and the ruler allows, for the first axis, to dispense with the usual casings of the kinematics, the slide and the linear measuring system.

[0115] The machine tool of the invention presents a reduction in environmental impact through:

[0116] its compactness,

[0117] the reduction of masses in general and more particularly of masses in motion,

[0118] eliminating the need to wash the frame by optimizing chip evacuation.

[0119] Although machining by chip removal constitutes the application envisaged in the first place and preferred for the implementation of the machine tool of the invention, it can also be used for other operations, such as:

[0120] - friction welding,

[0121] - abrasion machining,

[0122] - etc...

[0123] Similarly, based on the same architecture but without implementing a rotating spindle, other applications are envisaged, such as:

[0124] - additive manufacturing or 3D printing,

[0125] - water jet machining,

[0126] - electroerosion,

[0127] - machining or cutting by laser beam,

[0128] - etc..,

[0129] The fundamental concepts of the invention having just been set out above in their most basic form, other details and characteristics will emerge more clearly on reading the non-limiting examples of embodiments of machine tools in accordance with the invention.

[0130] BRIEF DESCRIPTION OF THE DRAWINGS

[0131] Figure 1 is a schematic drawing of a general perspective view of an embodiment of a machining machine tool according to the invention;

[0132] Figure 2 is a kinematic diagram of the machine tool of the invention

[0133] Figure 3 is a schematic drawing of a perspective view of the positioning module in a deployed position;

[0134] Figure 4 is a schematic drawing of a perspective side view of the positioning module in a folded position;

[0135] Figure 4a is a schematic drawing of a bottom perspective view of the positioning module in a folded position;

[0136] Figure 5 is a schematic drawing of a sectional view along a section plane passing through the second and third axes of the first arm;

[0137] Figure 6 is an explanatory diagram of the operation of a position control implemented by the machine tool of the invention;

[0138] Figure 7 is a schematic drawing of a sectional top view of the second arm;

[0139] Figure 8 is a schematic drawing of a perspective view of the wrist and rotating work spindle assembly;

[0140] Figure 9 is a schematic drawing of a detailed sectional view along a sectional plane passing through the fifth and sixth axes of the free end of the positioning module;

[0141] Figure 10 is a schematic drawing of a perspective view of a variant of the second arm;

[0142] Figure 11 is a schematic drawing of a perspective view of a variant of the motorization of the first arm;

[0143] Figure 12 is a schematic drawing of a perspective view of a machine tool configuration comprising several positioning modules on a single frame,

[0144] DESCRIPTION OF PREFERRED EMBODIMENTS

[0145] As illustrated by Figure 1, the machining machine tool referenced M as a whole comprises a frame 100 and a positioning module P of a rotating work spindle here constituted by an electro-spindle 200 carrying a tool 210.

[0146] A workpiece holder subassembly B is positioned in front of the frame 100 and is associated with a chip recovery and evacuation subassembly C. An operator O can interact with the workpiece holder subassembly,

[0147] Figure 2 illustrates the kinematic links implemented by the machine tool M. Figures 3 and 4 illustrate the positioning module P alone.

[0148] As illustrated, said positioning module P is an articulated structure which ensures the movement of the tool 210 relative to the fixed frame 100 in implementing a plurality of links on only six axes numbered from A1 to A6.

[0149] To do this, the positioning module P comprises a carriage 300 supporting articulated arms 400 and 500 at the end of which there is a sub-assembly forming a wrist 600 accommodating the efectro-spindle 200.

[0150] More precisely, the positioning module P implements the links described below.

[0151] The carriage 300 is in sliding connection with the frame 100 for a horizontal translational movement along a first axis A1. The movement is motorized by means of a linear motor 110.

[0152] The frame 100 is preformed so as to accommodate two horizontal rails 120 and 130 arranged parallel to the first axis A1 of translational movement and offset in height. Said carriage 300 is preformed and equipped with guide pads 310 to cooperate with said rails 120 and 130 in order to implement the sliding connection along the axis A1. The frame 100 comprises a vertical flat surface 140 with a longitudinal axis parallel to the rails 120 and 130 and intended to accommodate the secondary part 112 of the linear motor 110. Said flat surface 140 is arranged higher than said rails 120 and 130 and is offset laterally.

[0153] Said carriage 300 is preformed to accommodate the primary part 111 (see fig. 4a) of the linear motor 110,

[0154] Such an offset and raised arrangement has the advantage of bringing the motor 110 closer to the center of gravity of the positioning module P,

[0155] The carriage 300 is preformed to guide the first arm 400 in rotation along an axis A2 parallel to the axis A1. To do this, it comprises two symmetrical bearings 320 and 330 between which a first end 410 of the first arm 400 rotates.

[0156] The first arm 400 is itself preformed at its second end 420 with two symmetrical bearings 430 and 440 to guide the second arm 500 in rotation along an axis A3 parallel to the axes A1 and A2. A first end 510 of said second arm 500 is inserted between the two bearings 430 and 440. This first arm 400 comprises, between the axis A2 and the axis A3, a volume concave 450 allowing an increased angular travel of the second arm 500 which can be housed in this concavity in the folded position illustrated by figure 4. In addition, the concave volume 450 starts from the lower end 410 and is defined so that in the folded position, this concave volume prevents the rear part of the electro-spindle 200 from abutting against the first arm 400 when in the folded position the electro-spindle 200 is oriented with its axis A6 intersecting the longitudinal axis of the arm 400 as illustrated by figure 4a,

[0157] The second arm 500 adopts a hollow tubular body and accommodates at its second end 520 a subassembly forming a wrist 600 which implements:

[0158] a third motorized pivot link for a rotational movement along an axis A4 perpendicular to axes A1, A2 and A3, and

[0159] - a fourth motorized pivot link for a rotational movement of the 200 spindle electro-spindle along an A5 axis perpendicular to the fourth axis,

[0160] The electro-spindle 200 ensures the rotational movement of the tool 210 along an axis A6 perpendicular to the axis A5. The rotation axis A6 of the tool 210 moves in a movement plane passing through the axis A4 of the third pivot connection.

[0161] The axis A4 of the third pivot connection merges with the axis of the tubular body constituting the second arm 500 and is positioned in the median plane defined between the two bearings 430 and 440 guiding the rotation of the pivot connection along the axis A3 and in that merged with the first defined between the two bearings 320 and 330 provided by the carriage 300. The second arm 500 is preformed so that the axis A4 intersects perpendicularly with the axis A5 and does not intersect with the axis A3 thanks to an offset created by the geometry of the end 510 which offsets the axis A4 corresponding to the axis of the tubular body of the second arm 500,

[0162] All pivot connections are motorized using a geared motor consisting of a motor and a reducer,

[0163] As illustrated in Figures 5 and 9, the pivot connections on axes A2, A3 and A5 are implemented by two bearings each: a main bearing and a secondary bearing.

[0164] More precisely, as illustrated by figure 5, the pivot connection implemented along the axis A2 between the lower end 410 of the arm 400 and the carriage 300 is guided by the two bearings 320 and 330. The rotational drive is implemented by means of a motor 321 associated with a reducer 322. This motor 321 is also associated with a first encoder 323 ensuring a measurement of the speed only

[0165] The rotationally driven part of the reducer 322 is fixed to one side of the end 410 of the first arm 400 to transmit the rotational movement. The bearing 320 providing guidance on this side is called the main one because it is closest to the motor 321.

[0166] The second side of the end 410 is equipped with an axial extension 331 which, guided in rotation by the second bearing 330 called secondary or recovery, is associated with a second encoder 332 ensuring a measurement of the position,

[0167] The same applies to the pivot links for the A3 and A5 axes.

[0168] Thus, also illustrated by figure 5, the pivot connection implemented along the axis A3 between the upper end 420 of the arm 400 and the second arm 500 is guided by the two bearings 430 and 440. The rotational drive is implemented by means of a motor 431 associated with a reducer 432. This motor 431 is also associated with a first encoder 433 ensuring a measurement of the speed only.

[0169] The rotationally driven part of the reducer 432 is fixed to one side of the end 510 of the second arm 500 to transmit the rotational movement. The bearing 430 providing guidance on this side is called the main one because it is closest to the motor 431.

[0170] The second side of the end 510 is equipped with an axial extension 441 which, guided in rotation by the second bearing 440 called secondary or recovery, is associated with a second encoder 442 ensuring a measurement of the position.

[0171] Finally, as illustrated by figure 9, the pivot connection implemented along the axis A5 in the wrist 600 to guide the electro-spindle 200 in rotation along a plane perpendicular to the axis A5 is guided by the two bearings 610 and 620. The rotation drive is implemented by means of a geared motor 611. This 611 geared motor is equipped with a first encoder ensuring speed measurement only,

[0172] The rotating part of the geared motor 61 is fixed to one side of the sleeve 220 accommodating the electro-spindle 200 to transmit the rotational movement along the axis A5. The bearing 610 providing guidance on this side is called the main one because it is closest to the geared motor 611.

[0173] The sheath 220 on its portion arranged opposite that cooperating with the geared motor 611 is preformed to be guided in rotation by the second bearing 620 called secondary or recovery and is associated with a second encoder 622 ensuring a measurement of the position,

[0174] The presence on these pivot links of two encoders, one linked directly to the motor and the other arranged in the drive chain after the kinematics of the reducer makes it possible to implement the control illustrated by figure 6.

[0175] As illustrated in Figure 6, the machine tool is controlled by a control unit 700 called CNC processing with instructions for each axis of the two-bearing pivot links (but also that implemented with a single bearing for the A4 axis) described above, a servo loop:

[0176] of position 710,

[0177] speed 720, and

[0178] of torque 730.

[0179] Each loop is equipped with a regulator called PID (proportional, integral, derivative). Each PID is associated with a data input module including the parameter setpoint and the data returning from the loop. The PIDs associated with their respective input form a subset called a drive.

[0180] As illustrated, the pivot link comprises a motor M associated with a reducer kinematics G and two encoders E1 and E2. The first encoder E1 is a speed encoder only. The second encoder E2 is a position encoder symbolizing the encoders 332, 442, and 622 described above. It is located after the reducer kinematics G and allows precise feedback of the measured positions for the closed-loop operation of said servocontrol.

[0181] As illustrated, the position information coming from the second encoder located downstream of the reducer returns via the loop 710 downstream of the digital control unit 700 upstream of the PID processing the position setpoint. The speed of the motor is therefore directly regulated to obtain the desired position without going through the digital control unit.

[0182] As explained above, it is the rigidity of the different components which allows the implementation of such position control.

[0183] Contributing to this rigidity and precision, the masses of the different components are defined and distributed so that due to the overhang formed, the reducers of the motors of the first and second pivot links respectively on axes A2 and A3 are preloaded. According to a preferred embodiment, these reducers are cycloidal without play.

[0184] According to a preferred embodiment, the reducers of the motors of the third and fourth pivot links respectively on the axes A4 and A5 are harmonic driven.

[0185] These characteristics prevent the presence of play in the reducers.

[0186] The machine tool M comprises a plurality of cables and pipes for supplying energy and transmitting the orders and information necessary for the operation of the axes and the electro-spindle 200. These cables and pipes are arranged in the form of a winding so that, during rotational movements, they are subjected to bending stresses more than to torsional stresses.

[0187] As illustrated by figure 7, the tubular body constituting the second arm 500 is provided with a hollow core 530 in order to accommodate such a winding 540 (see figure 8) which takes into account the rotation along the axis A4.

[0188] More precisely, the hollow core 530 of the second arm 500 accommodates a winding shaft 550 and a concentric sleeve 560 defining a winding volume of a single sheath grouping together cables and pipes, the radius of curvature of the cables and pipes in the winding volume evolving according to the angle of rotation of the wrist 600 along the fourth axis A4. The sleeve 560 limits the expansion of the winding in said volume.

[0189] The winding shaft 550 is itself provided with a hollow core 551 into which a rotating joint 552 opens for the purpose of supplying hydraulic energy for clamping and unclamping the tool 210.

[0190] As illustrated in Figure 9, the pivot connection along axis A5 also accommodates a slightly different winding device 630 in that each pipe or cable has a dedicated winding roller.

[0191] Thus, the second bearing 620 of the wrist subassembly 600 guides in rotation a rotating part secured to the sheath 220 receiving the electro-spindle 200. This rotating part is equipped with the winding device 630 for the cables and pipes necessary for the supply of electrical energy and for lubrication so that the radius of curvature of said cables and pipes varies according to the angular position of the electro-spindle along the axis A5.

[0192] Likewise, the geared motor 611 is axially crossed by a rotating joint 614 (with seven ways according to the illustrated embodiment), for the supply of hydraulic and pneumatic energy to the electro-spindle 200.

[0193] As illustrated by figures 7 and 8, the subassembly called wrist 600 forms an independent assembly with the electro-spindle 200 and with the winding shaft 550 and the winding 540. This assembly is introduced and fixed in the second arm 500 by means of an interface flange 570 which is fixed on a fixing collar 580 equipping the end 520 of the second arm 500. Thus, said assembly comprising in particular the different motors and reducers dedicated to axes 4, 5 and 6 can be easily mounted, disassembled and extracted from the rest of the machine. It should be noted that a second encoder 571 (in addition to that equipping the motor 572) also equips this pivot connection along the axis A4.

[0194] According to the configuration illustrated by the preceding figures, for the implementation of the pivot connection along the axis A3, the first end 510 of the second arm 500 was preformed to be accommodated between the two bearings 430 and 440 equipping the second end 420 of the first arm 400.

[0195] Figure 10 illustrates a different configuration regarding the implementation of the pivot link on the A3 axis.

[0196] In this new configuration, said second arm 500' comprises two ends, a first end 510' crossed by the third axis of rotation A3 and a second end 520* receiving the subassembly called wrist 600'. The difference lies at the level of the first end 510' which is equipped with two bearings 611' and 512' to guide in rotation along the third axis A3 the second arm 500'. Said two bearings 511' and 512' are in fact spaced apart so as to come on either side of the second end 420' of the first arm 400'.

[0197] The second end 420' crossed by the third axis of rotation A3 of the first arm 400' is equipped with two bearings 430' and 440' to guide the second arm 500' in rotation along the third axis A3, the geared motor 431' is here arranged between the two bearings 430' and 440' of the second end 420' of the first arm 400'.

[0198] It is understood that the symmetrical design of the carriage 100, the bearings of the axis A2 and the first arm 400 integrating the bearings of the axis A3 allows the geared motors of these axes to be installed either on the right or on the left. It has the advantage of reducing the size on one of the side faces of the positioning module. It is thus possible to choose the versions of the positioning modules (reduced size on one or other of the side faces) according to the machine installation constraints. This advantage is particularly interesting in a machine configuration with two working units, sharing the same slide on the axis Al. It allows for a minimum distance on this axis between the two positioning modules, thanks to the “external” installation of the geared motors,

[0199] Figure 12 illustrates such a configuration where the two positioning modules P and P' can move closer together without their respective motorizations coming into conflict. Another characteristic illustrated by this figure concerns the frame which is here designed in juxtaposable and removable length units 100a and 100b, allowing the reception of a plurality of positioning modules.

[0200] The said symmetrical design can also allow the integration of an additional motorization or a balancing system opposite the main motorization of the axis, with the aim of increasing the machining capacities, reducing the energy consumption or increasing the service life of the components (such as the reducers) as illustrated by figure 11 or a second geared motor M2 is arranged opposite the first M1 on the symmetrical bearing 330 ensuring the rotational guidance along the axis A2,

[0201] It is understood that the machining machine tool which has just been described and represented above has been done so with a view to disclosure rather than limitation. Of course, various arrangements, modifications and improvements may be made to the above examples, without departing from the scope of the invention.

Claims

Claims

1. Machine tool (M) comprising a frame (100) and at least one positioning module (P) for a rotating work spindle (200), said positioning module (P) ensuring the movement of the rotating work spindle (200) relative to the fixed frame (100) by implementing the following connections: - a sliding connection for horizontal translational movement along a first axis (A1) of a carriage (300) relative to the frame (100), - a first pivot connection for a rotational movement along a second axis (A2) parallel to the first of a first arm (400) relative to the carriage (300), - a second pivot connection for a rotational movement along a third axis (A3) parallel to the first two of a second arm (500) relative to the first arm (400), ~ a third pivot connection for a rotational movement along a fourth axis (A4) included in a plane perpendicular to the first three axes, - a fourth pivot connection for a rotational movement of a rotating work spindle support (200) along a fifth axis (A5) perpendicular to the fourth axis (A4), the implementation of the pivot connections along the fourth axis (A4) and the fifth axis (A5) being carried out by a subassembly called wrist (600), the rotating work spindle (200) ensuring the rotational movement of a tool (210) along a sixth axis (A6) perpendicular to the fifth axis (A5), CHARACTERIZED BY THE FACT THAT the pivot connections on the second axis (A2), the third axis (A3) and the fifth axis (A5) are implemented by two bearings each: a main bearing and a secondary bearing distant from each other, the fourth axis (A4) of the third pivot connection is positioned in a median plane defined between the two bearings guiding the rotation of the pivot connection along the third axis (A3), these pivot links each being the subject of a motorization integrating a geared motor composed of a motor and a reducer, the masses of the different components being defined and distributed so that due to the overhang formed, the reducers of the motorizations of the first and second pivot links are preloaded, the machine tool being controlled by a control unit associated for each axis of the pivot links, with a variator to process closed-loop control loops, each axis of the pivot links comprising two measurement systems with a first encoder arranged before the reducer ensuring speed measurement for speed regulation purposes and a second encoder arranged after the reducer ensuring position measurement for the closed loop of a position control, said position measurement feedback from the encoder positioned after the reducer being made at the variator,the sixth axis of rotation (A6) of the tool (210) moving in a plane of movement passing through the fourth axis (A4) of the third pivot link.,

2. Machine tool (M) according to claim 1, CHARACTERIZED BY THE FACT THAT the bearings (320, 330 and 430, 440) supporting the second axis (A2) and the third axis (A3) are symmetrical.

3. Machine tool (M) according to claim 1 or 2, CHARACTERIZED BY THE FACT THAT the second arm (500) is preformed so that the fourth axis (A4) of rotation intersects perpendicularly with the fifth axis (A5) of rotation and does not intersect with the third axis (A3) of rotation.

4. Machine tool (M) according to any one of claims 1 to 3, CHARACTERIZED BY THE FACT THAT said first arm (400) comprises two ends (410, 420), a first end (410) crossed by the second axis (A2) of rotation and a second end (420) crossed by the third axis (A3) of rotation, said second end (420) being equipped with two bearings (430, 440) for guiding the second arm (500) in rotation along the third axis (A3), said second arm (500) comprises two ends, a first end (510) crossed by the third axis (A3) of rotation and a second end (520) receiving the subassembly called wrist (600), the first end (510) of the second arm (500) being preformed to be received between the two bearings (430, 440) equipping the second end (4.20) of the first arm (400).

5. Machine tool (M) according to the claim according to any one of claims 1 to 3, CHARACTERIZED BY THE FACT THAT said first arm (400') comprises two ends, a first end crossed by the second axis (A2) of rotation and a second end (420') crossed by the third axis (A3) of rotation, said second arm (500') comprises two ends (510', 520'), a first end (510') crossed by the third axis (A3) of rotation and a second end (520') receiving the subassembly called wrist, the first end (510') of the second arm (500') being equipped with two bearings (51 T, 512') for guiding in rotation along the third axis (A3) the second arm (500'), said two bearings (51 T, 512') being spaced apart so as to come from and on the other side of the second end (420') of the first arm (400*).

6. Machine tool (M) according to any one of claims 1 to 5, CHARACTERIZED BY THE FACT THAT the first arm (400) comprises between the second axis (A2) and the third axis (A3) of rotation, a concave volume (450) allowing an increased angular travel of the second arm (500) which can be housed in this concavity in the folded position.

7. Machine tool (M) according to any one of claims 1 to 6, CHARACTERIZED BY THE FACT THAT the subassembly called wrist (600) forms an assembly with the rotating work spindle (200), an assembly which, comprising the motors and reducers associated with the fourth, fifth and sixth axes, is introduced and fixed in the second arm (500) by means of an interface flange (570) so that said assembly can be easily mounted, dismounted and extracted from the rest of the machine (M).

8. Machine tool (M) according to any one of claims 1 to 7, CHARACTERIZED BY THE FACT THAT it comprises cables and pipes for supplying the necessary energy to the rotating work spindle (200), the second arm (500) and the wrist (600) being provided with a hollow core in order to accommodate them.

9. Machine tool (M) according to claim 8, CHARACTERIZED BY THE FACT THAT it comprises on the fourth axis (A4) and the fifth axis (A5) of rotation, means for winding the cables and pipes preventing their twisting during movements so that they only work in flexion.

10. Machine tool (M) according to claim 6, CHARACTERIZED BY THE FACT THAT said first arm (400) comprises two ends (410, 420), a first end (410) crossed by the second axis (A2) of rotation and a second end (420) crossed by the third axis (A3) of rotation, the concave volume (450) starting from the lower end and being defined so that in the folded position, this concave volume (450) prevents the rear part of the rotating work spindle (200) from abutting against the first arm (400).

11. Machine tool (M) according to claim 5, CHARACTERIZED BY THE FACT THAT the second end (420') of the first arm (400') crossed by the third axis (A3) of rotation is equipped with two bearings for guiding the second arm (500') in rotation along the third axis (A3), the geared motor (431') being arranged between the two bearings of the second end (420') of the first arm (400').

12. Machine tool (M) according to claim 8 or 9, CHARACTERIZED BY THE FACT THAT the hollow core of the second arm (500) accommodates a winding shaft (550) and a concentric jacket (560) defining a winding volume of a single sheath grouping together cables and pipes, the radius of curvature of the cables and pipes in the winding volume evolving according to the angle of rotation of the wrist (600) along the fourth axis (A4).

13. Machine tool (M) according to any one of the preceding claims, CHARACTERIZED BY THE FACT THAT the sub- wrist assembly (600) is equipped with two bearings (610, 620) to implement the pivot connection according to the fifth axis (A5) and between which the rotating work spindle (200) rotates, a first bearing accommodating a geared motor (611) crossed axially by a rotating joint, for the supply of hydraulic and pneumatic energy to the rotating work spindle (200),

14. Machine tool (M) according to claim 13, CHARACTERIZED BY THE FACT THAT the second bearing (620) of the wrist subassembly (600) guides in rotation a rotating part integral with the rotating working spindle (200) and equipped with a winding device (630) for the cables and pipes necessary for the supply of electrical energy and for lubrication so that the radius of curvature of said cables and pipes varies according to the angular position of the rotating working spindle (200) along the fifth axis (A5).

15. Machine tool (M) according to any one of the preceding claims, CHARACTERIZED BY THE FACT THAT said frame (100) is preformed so as to accommodate two horizontal rails (120 and 130) arranged parallel to the first axis (A1) of translational movement and offset in height, said carriage (300) being preformed to cooperate with said rails,

16. Machine tool (M) according to claim 15, CHARACTERIZED BY THE FACT THAT the translation along the first axis (A1) is motorized according to one of the following technologies: - by means of a linear motor (110), - by means of a ball screw motor, - by means of a rack,

17. Machine tool (M) according to claim 15, CHARACTERIZED BY THE FACT THAT the translation along the first axis (A1) is motorized by means of a linear motor (110) and said frame (100) comprises a vertical flat surface (140) with a longitudinal axis parallel to the rails and intended to accommodate the secondary part (112) of the linear motor (110), said flat surface (140) being arranged higher than said rails (120, 130) and offset laterally, said carriage (300) being preformed to accommodate the primary part (111) of the linear motor (110),

18. Machine tool (M) according to any one of claims 15 to 17, CHARACTERIZED BY THE FACT THAT the frame (100) accommodates guide and motorization elements along the first axis (A1) and is designed in juxtaposable and removable length units (100a, 100b).

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