EP2361173A1

EP2361173A1 - Method and device for producing parts, in particular elongate parts of revolution, by machining a bar fixed in rotation

Info

Publication number: EP2361173A1
Application number: EP09760922A
Authority: EP
Inventors: Christian Fromholz
Original assignee: SIIMO SAS
Current assignee: SIIMO SAS
Priority date: 2008-10-23
Filing date: 2009-10-23
Publication date: 2011-08-31
Anticipated expiration: 2029-10-23
Also published as: FR2943574A3; FR2943574B3; FR2937576A1; EP2361173B1; WO2010046570A1; FR2937576B3

Abstract

Device for manufacturing elongate parts of revolution, in particular made of wood, having a variable cross section in the longitudinal direction, by machining a bar (B), the device comprising a fixed chassis (1) bearing guide means (2) for guiding said bar in translation and maintaining it fixed in rotation, a turning assembly (4) which is rotated and comprises a plate (41) and at least two rotating tools (3) supported by movable supports (5) guided with respect to the plate and on which the tools are rotated about respective axes of rotation (A2) substantially parallel to the main axis, and the device comprises means for controlling the position of the supports which comprise drive means (92) fastened to the chassis and mechanical transmission means (71 to 76) providing a connection between said drive means and said supports (5), such that the distance between the axes of the tools and the main axis is continuously adjustable by controlling said drive means (92).

Description

Method and device for producing parts, in particular elongated parts of revolution, by machining a fixed bar in rotation

The present invention relates to a novel method and a new device for producing parts, in particular pieces of elongated revolution and of variable section in the longitudinal direction, by machining a bar held fixed in rotation.

By parts of revolution, we will hear thereafter any piece of circular section, but also cross-sectional parts of generally elliptical shape or even, for some possible applications, of general polygonal shape, or twisted parts, etc.

By machining, it will be understood in general any method of forming by removal of material, whether by cutting tools, abrasive, etc..

The invention aims in particular, but not exclusively, the production of elongated wooden parts in a main axial direction. pa ^r ticular axisymmetric, from long wooden bar. It can also be applied to the production of parts made of other materials, especially plastics, synthetic materials. The invention is particularly applicable to the realization, from a long bar, small parts section in relation to their length. It also applies to the production of larger parts by a machining transformation of a bar of typically square section, of any length, straight or curved, into parts of axisymmetric section: circular, oval, square, possibly helical etc. variable longitudinal profile and respectively straight or curved.

Traditional turning devices are known for producing parts of revolution. In these devices, the bar to be machined is maintained thanks to a mandrel with or without counterpaint or between points ε ^~ is rotated about ^' its axis. The machining άu profile to be achieved is then done by combining the movement, from one end to the other of the bar, of one or more tools and the variation of the spacing of these tools relative to the axis of the room. The variation of this spacing is generally performed either mechanically or by a numerical control system. However, these devices have several disadvantages. Indeed, the length of the workpiece is limited by the capacity of the machine. Traditional turning processes, although mostly automated, have a limited length capacity in general of 5 to 6 meters maximum for long length standards. The longer the part, the more the machine with this device is bulky and expensive. In the case of long, thin parts, there is a risk of bending or vibration ^'mid-length, which can cause unacceptable defects of machining quality. The turning process is by nature discontinuous, the loading and unloading of the machined part necessitating the stopping of the turning operation. It allows the realization of only one piece at a time. As a result, the efficiency of these devices is quite low, especially for heavy and bulky parts.

In addition, the sections made are necessarily circular, the parts must be straight. The production of parts such as for example twisted table legs, is more the special machine that filming and requires several successive operations. The turning of bent parts can only be achieved with the help of an expensive machining center, with long machining operations (programming, positioning of the part, machining, ...) hence a cost particularly high production. Moreover, processes and manufacturing machines are already known, based on the principle of rotating one or more tools around the machined part which remains fixed in rotation. One of these known devices, for the manufacture of cylindrical posts, is composed of an electric motor which drives a hollow mandrel equipped with at least two blades oriented towards the center and uniformly: distributed on the inside of the mandrel. The blades thus driven in rotation about the machining axis, allow to machine a workpiece along its axis and according to a fixed diameter defined by the position of the blades relative to the axis. This device makes it possible to machine long lengths of posts, but has several disadvantages. It allows the realization of only one piece at a time. Nor does it allow variations in diameter during machining. In addition, for each new diameter, reposition the blades and often disassemble and change the chuck according to the diameter to achieve. As a result, the efficiency of said device is very low, and the shapes of the products produced are limited to cylindrical shapes.

US1943649 discloses a machine for making wooden posts such as telephone poles. This machine comprises a set of two tools driven in rotation along their respective axes, mounted on a plate which is itself driven in rotation about a main axis corresponding to the axis of the pole. The tools are arranged on the plate symmetrically opposite with respect to the axis of rotation thereof, and the radial distance between the axes of rotation of the tools and the axis of rotation of the plate can be adjusted by an on-board electric motor. the tray. It follows that this system uses a motor for rotating the plate, a motor for adjusting the radial position of the tools and a motor by tool for their rotation drive, four motors all on board the rotating part and thus requiring electrical commutators sliding contact for their power supply. The production of such collectors is complicated when the electrical current intensities are high. This also causes problems of electrical insulation and therefore safety. The size of these motors is important and moreover, these motors have a relatively large mass driven in rotation, and significant centrifugal forces result during the rotation of the plate. The reduction mechanisms used between the axial position adjustment motor and the tool supports do not allow rapid change of radial position of the tools.

The present invention aims to solve the problems mentioned above, and aims in particular to provide a method and a device for machining on straight or curved bars of any length, parts of both circular and axisymmetric sections. in any given longitudinal profile. It also aims to allow the use of such a device for making small parts in section, and having a small footprint. It is also aimed at providing a new machining device that enables continuous, high-speed machining capable of machining very thin bars, changing profiles instantly without changing tools, and machining closer to the maintenance. of the bar, thus eliminating the inevitable vibration and buckling effects during manufacturing by turning long pieces and small relative section. It also aims to provide a method and a device also suitable for machining heavy and bulky parts such as profiled bars, poles beams and the like, obtained from ^'bars machinable material. Either for small or large pieces, the invention is including the machining of soft materials such as wood _f, particularly .in balsa, cork and / or plastics such as polyurethane foam, until hardwoods, resinous or not, such as beech or Ipe and other materials.

With these objectives in view, the subject of the invention is a device for producing parts of revolution, or of a similar general shape, in particular of elongate and longitudinally variable wooden parts in the longitudinal direction, by machining a bar maintained fixed in rotation, the device comprising a fixed frame carrying guide means for guiding said bar in translation along a main axis and maintaining it fixed in rotation, a rotating assembly driven in rotation relative to the frame along the main axis, rotating assembly comprising a plate and at least two rotary tools supported by movable supports guided relative to the plate in a plane orthogonal to the main axis and on which the tools are rotated along respective axes of rotation substantially parallel to the main axis, and the device comprising means for controlling the position of the supports for adjusting the radial positioning of the outlets. they relative to the main axis.

According to the invention, the device is characterized in that the control means the position of the supports comprise motor means secured to the chassis and mechanical transmission means ensuring the connection between said motor means and ^• said supports, so that the distance between the axes of the tools and the main axis is continuously adjustable by controlling said fixed motor. Thus, the invention makes it possible to ensure a -omzinue variation of the radial position of the tools during the. ^• Implementation of the device, and therefore during the rotation of the tray, without the need to use a motor on board for this purpose. The mass of the rotating parts can thus be reduced and the inertia and / or unbalance forces can be very reduced. In addition, it is not necessary to use a power supply by rubbing contact for such an onboard power plant.

According to a preferred arrangement, said mechanical transmission means comprise a set of bearings movable in the direction of the main axis, the bearing assembly comprising a first bearing driven in axial translation by said drive means and a second bearing connected in rotation. with the assembly rotating and in translation with the first bearing, the rotating assembly comprising mechanical connection means between the second bearing and the tool supports for converting the axial translational movement of the second bearing into radial displacement of the axes of the tools .

Preferably, each movable support is a lever pivotally mounted on the plate along a pivot axis parallel to the main axis, each tool is rotatably mounted on a first arm of said lever at a distance from its pivot axis, and said connecting means mechanical comprise, associated with each arm, a reversible screw-nut assembly connecting the second bearing to the lever so that an axial displacement of the second bearing relative to the plate causes a pivoting of the lever.

According to a particular embodiment, the reversible screw-nut system comprises, at its end connected to the lever, a pin eccentric relative to the axis of the screw-nut system and which engages in a groove formed at the end of a second arm of the lever. Preferably, the stud is mounted eccentrically, so as to adjust, rotatior. said tenon on itself, - the desired position of the corresponding lever: • based on the angular position of the end of the screw-nut system which carries it, to ensure accurate positioning radiai ^"and similar cutting tools .

According to another embodiment, the reversible screw-nut system comprises, at its end connected to the lever, a pinion engaging with a toothed sector formed on the lever.

Preferably, the nut of the reversible nut screw system is fixed on the second bearing, and the screw is rotatable, guided in rotation on the plate, and its end is connected to the lever.

According to another particular arrangement, the rotating assembly comprises rotational linking means linking in rotation the plate and the second bearing. These means of connection in rotation preferably comprise at least one rod integral with the plate and parallel to the main axis and sliding in a guide ring of the second bearing.

The rotating assembly is preferably rotated by a motor attached to the frame and connected to the turntable by a belt.

According to a particular embodiment, the motor means for controlling the displacement in axial translation of the first bearing comprise a fixed motor on the frame and the first bearing is driven in axial translation by a set of racks sliding parallel to the main axis and cooperating with pinions driven in rotation by said fixed motor.

Alternatively, the motor means comprise a fixed motor on the frame and the first bearing is a toothed nut having an internal thread engaged by screwing on a hub of the chassis centered on the main axis, the toothed nut cooperating with a piσnor. rotated by said fixed motor.

The motor means could also include one or more actuators acting on the first bearing to move it in axial translation.

Each tool is preferably rotated on its support lever by a set of pulleys and belts connecting the tool to a drive roller held in rolling contact with a fixed inner ring secured to the frame. Thus, the rotation of the plate frictionally causes the rotation of the roller which in turn causes the rotation of the tool by the set of pulleys and belts. Typically, the roller is connected by a first belt to an intermediate shaft rotating in a bearing centered on the pivot axis of the tool support lever, and the shaft is connected to the tool by a second belt. Thus, the rotational drive of the tool can be assured regardless of the pivoting position of the tool support lever.

Moreover, the roller is preferably rotatably mounted on a roller-holder arm pivotally mounted on the tray according .l'axe pivot lever tool holder, so that the roller is firmly pressed against the inner ring, and ^r as much more strongly than the speed of rotation is higher, because of the centrifugal force exerted then on the roller bearing arm and the roller. A return spring may be arranged between the plate and the roller arm to ensure the contact without sliding between the roller and the ring even at low speed of rotation of the rotating assembly.

According to an alternative embodiment of the rotary drive of the tools, the device may comprise a rotary ring rotatably mounted on the chassis and driven in rotation by a third fixed motor on the frame, and the intermediate shaft comprises a wheel cooperating with said rotary ring so as to be rotated by the rotation of the rotary ring, and to rotate the tool, by a set of pulleys and belts, as in the previous embodiment. This arrangement is particularly suitable for the production of parts requiring a low speed of rotation of the plate, for example of the order of one turn per second, for non-circular section parts where the tools must move radially during the rotation of the tray. In such a case, the rotation of the tools by a specific motor and by means of the rotary ring makes it possible to ensure a sufficient speed of rotation of the tools, despite the low speed of rotation of the rotating assembly. In general, this arrangement makes it possible to make the rotation speed of the rotating assembly and the speed of rotation of the cutting tools independent of each other. Of course, the sets of pulleys and belts should be understood as also encompassing systems with toothed wheels and chains or other drive systems functionally equivalent and easily implemented by those skilled in the art. Similarly, the roller may be replaced by a pinion meshing with an internal toothing of the fixed ring. Also, the wheel cooperating with the rotary ring may be a toothed wheel in engagement with an internal toothing of this ring of the set of characteristics which have just been indicated, taken in their various possible combinations, it will be understood that one of the main advantages of the invention is to allow the machining of parts of revolution, according to the definition which was given at the beginning of this description, from long bars of substantially square section, or rectangular, by rotating tools in an epicyclic movement around the said bar, and that by a device that does not require the use αe embedded motors on rotating bodies. As a result, the rotating assembly is generally compact in order to minimize the centrifugal forces and thus reduce the weight of the rotating structures, their cost and the energy requirements necessary for their rotation. A motor located mainly outside the rotating structure allows to lighten the structure and, especially in the case of high rotation speed of the plate, to reduce possible màésxrable vibrations. If necessary, however, it will be possible to use onboard motors for driving the tools in rotation, for example via the intermediate arrays mentioned above.

The invention also relates to a method of producing parts, in particular elongated parts of revolution and of variable section in the longitudinal direction, by machining a bar held fixed in rotation. According to this method, implementing the device described above, relatively moves the device and the bar, held fixed in rotation, in the direction of the main axis and the bar is machined by the tools, according to a longitudinal profile and / or circumferential desired, controlling, depending on the desired profile, a radial displacement of the tools depending on the axial position of the bar relative to the frame and / or the circumferential position of the tools relative to the bar.

The method applies to the production of various parts having a longitudinal axis. It applies in particular, advantageously, to the production of such shaped pieces, of substantially shaped cross-section. circular, from for example glued wood bars, material that is commonly aismeπz feasible in the form of bars or posts of square or rectangular section, but not in the form of products of generally circular section.

Incidentally, the invention allows the production of bent parts, or from ^f a bent rod, which would not be possible by conventional turning process, involving the rotation of the relatively high speed part. It also allows easy realization of relatively short multiple parts axially from a long bar, without workpiece recovery operations or tool change. It also allows a continuous manufacturing process, simply by feeding the bars end to end, without interrupting the rotation of the tools. The invention allows a total sectioning in the case of series parts, by bringing the machined diameter in the vicinity of zero mm and then finalizing the sectioning by performing a point shift of the axis of the -barre. In any case, the cantilever of the bar or the workpiece can be greatly reduced, resulting in a better machining accuracy and total absence of vibration of the bar since it does not rotate. The productivity of the machine is no longer limited by the speed of rotation of the bar.

The rotary tools in the form of discs can be grinding wheels for machining parts made of soft material, such as, for example, balsa or cork, or synthetic foams _/ for example polyurethane. The replacement of grinding wheels by cutting tools allows the machining of softwood and / or hardwood, such as beech or Ipe, exotic wood. In general, the machining of any material is possible with ad hoc tools, the shape of the tools being determined so as to be able to make strong and rapid variations of sections according to the desired longitudinal profile.

The management of a phase shift of the section in function. advance allows for helicoidal shapes.

Other features and advantages will appear in the description which will be made of a machine according to the invention, as well as its implementation.

Reference is made to the accompanying drawings in which:

FIGS. 1 and 2 are a schematic illustration of the general principle of the invention,

FIG. 3 is an overall view of the machine, in perspective seen from the side where the machine is fed by the bar to be machined,

FIG. 4 is an overall view of the machine, in perspective seen from the rear side.

FIG. 5 is a perspective view showing the rotating assembly; FIG. 6 is a view in axial section showing the connection in rotation between the plate and the second bearing;

FIG. 7 is a view in axial section showing the mechanism for controlling the pivoting of the tool-carrying levers,

- Figure 8 is a sectional view of the mechanism for driving a tool in rotation, Figures 9 and 10 are views in axial section, respectively along the lines IX-IX and XX of Figure 11, .d ' an alternative embodiment of the machine, respectively showing the means for rotating the tools, and, in part, the means for controlling the pivoting of the tool support levers. FIG. 11 is a view schematically illustrating the pivoting of the support levers d / tools, shown here in another embodiment.

The diagrams of FIGS. 1 and 2 illustrate the general principle of the invention. A bar B, of square section, is held fixed in rotation and machined by rotary cutting tools 3 driven in rotation on their axes A2 according to the arrows Rl, the axes of the tools being themselves rotated along the arrow R2 around of the main axis Al of the machine. The bar B is moved in translation along the main axis A1 of the machine, in the direction of the arrow F1, the advance of the bar being provided in a manner known per se by a drive system and a motor, not shown. . The kinematics of the machine therefore consists in associating the translation movement Fl of the bar B to be shaped with a rotational movement R2 of the axes A2 of the tools 3 around the bar B.

The machine comprises a rotating assembly 4 comprising a plate 41 which supports the two cutting tools 3 diametrically opposed. Each tool can move radially relative to the main axis A1 of the machine, as will be seen later.

As will have already been understood, according to the invention, the bar B does not turn on itself. It is only subject to a longitudinal displacement, in its axial direction, through a guide piece 2. As soon as the output of the guide piece 2, said bar B is brought into contact with the tools, for example abrasive or cutting discs 3, each held on a tool holder rotated around said bar. From the exit of the guide piece, the bar is machined by the two tools 3 diametrically opposed to the main axis Al which is also the axis of the bar. Both tools 3 are located in the same section plane located closest to the guide piece 2, which distributes the cutting forces on both sides of the bar B and limits the bending forces on it.

I / spacing of the tool holder can be controlled by a numerical control which will then realize the profile of the piece previously stored in a computer file.

^• 1t will now describe in more detail a machine according to the invention. The machine represented in FIGS. 3 to 8 comprises a frame 1 on which is fixed rigidly a bell 11 inside which is mounted a rotating assembly 4 driven in rotation by a first motor 91. The rotating assembly 4 comprises in particular a plate 41. secured to a hub 42 guided in rotation on a bored rocket 12 integral with the frame and such that the bar B can pass axially in the bored rocket.

The plate 41 carries two movable tool supports consisting of levers 5 mounted diametrically opposite and symmetrical with respect to the main axis Al. Each lever 5 is pivotable along an axis A3, parallel to the main axis Al, in a through bore 411 of the plate 41. The lever 5 comprises a first arm 51 on the end of which is rotatably mounted the tool 3. The lever 5 comprises a second arm 52, inclined relative to the first arm 51 by an angle for example d approximately 100 °, as seen in Figure 5. The two levers 5 are facing so as to leave free between them a space of suitable shape and dimensions, sufficient for the passage of the bar B during machining. A drive roller 61 is rotatably mounted on the end of a roller support arm 6 which is also pivotally mounted in the bore 411 of the plate 41. The roller 41 is held in contact with the inner surface 131 of a 13 ring device integral with the bell 11, for example by a spring not shown. The stone 61 is connected in rotation by a first set of pulleys and belts 62 at one end of an intermediate shaft 63 passing through the roller bearing arm 6 and the lever 5 and guided therein along their common pivot axis A3. The other end of the intermediate shaft 63 is rotatably connected by a second set of pulleys and belt 64 to the tool 3. Thus, when the roller 61 is rotated by friction with the ring 13 when the plate 41 rotates it transmits its rotational movement to the intermediate shaft and then to the tool 3, without requiring additional specific motor.

To ensure the radial displacement of the tools, the machine comprises a fixed motor 92 on the frame which drives by belts 71 of the pinions meshing with racks 72 sliding in the frame parallel to the main axis and integral with a first bearing 73 centered on the main axis Al. This first bearing 73 forms with a second bearing 74 a set 7 of two bearings guided in rotation on one another and linked in translation, so that the assembly 7 is movable in translation according to the direction of the main axis, the first ^'bearing 73 being fixed against rotation relative to the frame because of its rigid connection with the racks 72, and the second bearing 74 according to the axial movements of the first bearing and of the racks, but which rotate relative to the frame along the axis Al. The second bearing is connected in rotation with the plate 41 by pins 44 secured to said plate, extending parallel to the axis Al and mount s sliding axially in guide bushes 75 integral with the second bearing. Other means of guiding in axial translation and rotational connection between the second bearing 74 and the plate 41 could also be used. The plate 41 is rotated by the motor 91, for example by a belt 911, and therefore rotates the second bearing 74, Furthermore, the second bearing 74 is also connected with the plate 41 and more particularly with two rotary cams 54 carried by this plate, by reversible screw-nut systems comprising a nut 77 rigidly fixed to the second bearing 74 and a screw 76 of which the end is guided in rotation on the plate 41 and carries a said cam, so that an axial displacement of the second bearing causes a rotation of the screw and thus of the cam 54. The cam 54 carries a stud 541 which cooperates with a groove 521 formed in the end of the second arm 52 of the lever 5, so that a rotation of the screw 76 and the cam 54 causes a pivoting of the lever 5, and consequently a radial displacement of the tool 3. The operation of the machine is as follows:

A bar B to be machined is fed in the axial direction Al to the tools. The motor 91 drives in rotation around the main axis Al the plate 41 and therefore the tool-carrying levers 5 and the tools 3. This causes the rollers 61 to rotate by friction on the ring 13 and, as previously indicated, the rotation tools on their own axes A2.

To vary the radial distance between the tools 3 and the bar B, and thus vary the machining radius, it controls the pivoting of the levers 5 by means of the motor 92, which causes the sliding of the racks 72 and the axial displacement of the set of bearings 7, which causes a rotation of the screws 76 and the cams 54, and finally the pivoting of the levers 5. Note that the use of a lever as described above to adjust the radial positioning of the tools allows a high clearance of the tools thanks to the reduced size of the support lever, and a high reactivity, necessary for the manufacture of small series parts or for the realization of non-circular sections in the case of small rotations of the plate, and this without increasing the centrifugal force generated by the device because of the small masses induced by this leviez system.

To precisely adjust the exact radial positions of the tools, and correct a possible difference in distance between each of the tools and the main axis Al, taking into account any differences in the diameter of the tools or other dimensional dispersions of the parts of the mechanism, the tenon 541 is an eccentric which thus makes it possible, by rotating it on itself, to adjust the pivoting position of the lever 5 with respect to the rotational position of the cam 54.

In the embodiment of FIGS. 9 and 11, the rotation drive of the tools is carried out independently of the rotational drive of the plate 41, by using a third motor 93 fixed to the chassis and which rotates a crown 81 rotatably mounted on the frame along the main axis A1, the rotation of each tool 3 is obtained through a pinion 82, carried by an intermediate shaft 63 'guided in rotation along the axis A3 on the turntable 41, and the pinion 82 rolling on the internal toothing of the ring gear 81. The rotation of the pinion 82 and the intermediate shaft 63 'is transmitted to the tool by a system of pulleys and belts 83, similarly to that of the first embodiment of FIG. production.

In this second embodiment also, the axial rack-and-pinion system of the bearings for controlling the pivoting of the tool-carrying levers is replaced by a toothed nut system in which a toothed nut 85 constituting the first bearing of the the bearing assembly 7, is screwed on the rocket 12 and rotated by a pinion 86 itself driven by the motor 92. The rotation of the motor 92 causes the screwing or unscrewing of the toothed nut 85, and therefore its axial displacement on the rocket. This displacement is transmitted to the second bearing 74, and thence, as in the first embodiment, to the reversible screw-nut systems and to the tool-carrying levers. FIG. 11 illustrates a variant of the control of the pivoting of the levers 5 by the screws 76 of the reversible screw-nut systems. In this case, the end of the screw 76 carries a gear 58 which meshes with a toothed sector 59 made on the lever 5.

The invention can also be applied to the production of non-axisymmetric parts, for example by controlling the radial positioning of the tools in a different manner for the two tools. Such an arrangement can for example be implemented using an onboard electric motor specific to each tool, to adjust the positioning of the tools independently of one another. Care should be taken not to create excessive imbalance of the machine, limiting the speed of rotation of the tool support around the machined bar.

Claims

1. Device for producing parts of revolution, in particular elongated and longitudinally variable wooden parts in the longitudinal direction, by machining a bar (B) held fixed in rotation, the device cpmportant a fixed frame (1) bearing guiding means (2) for guiding said bar in translation along a main axis (Al) and maintaining it fixed in rotation, a rotating assembly (4) driven in rotation relative to the frame along the main axis, the rotating assembly comprising a plate (41) and at least two rotary tools (3) supported by movable supports (5) guided relative to the plate in a plane orthogonal to the main axis and on which the tools are rotated along axes of respective rotation (A2) substantially parallel to the main axis, and the device comprising means for controlling the position of the supports for adjusting the radial positioning of the tools relative to the main axis, characterized in that the means for controlling the position of the supports comprise motor means (92) fixed to the frame and mechanical transmission means (71 to 76) providing the connection between said motor means and said supports (5), so that the distance between the axes of the tools and the main axis is continuously adjustable by controlling said motor means (92).

2. Device according to Claim 1, characterized in that said mechanical transmission means comprise a bearing assembly (7), ^movable in the direction of the main axis, the bearing assembly comprising a first bearing (73) driven in axial translation by said motor means and a second bearing (74) rotatably connected with the rotating assembly (4) and in translation with the first bearing, the tournar.z assembly having mechanical connection means (76, 77) between the second bearing (74) and the supports tools (5) for converting the axial translation movement of the second bearing into radial displacement of the axes of the tools

3. Device according to claim 2, characterized in that each movable support is a lever (5) pivotally mounted on the plate (41) along a pivot axis

(A3) parallel to the main axis, ^• each tool (3) is rotatably mounted on a first arm (51) of said lever remote from its pivot axis, and said mechanical connection means comprise, associated with each lever, reversible screw-nut assembly (76, 77) connecting the second bearing (74) to the lever (5) so that an axial displacement of the second bearing relative to the plate causes a pivoting of the lever.

4. Device according to claim 3, characterized in that the reversible screw-nut system (76, 77) comprises at its end connected to the lever (5), a pin (541) eccentric relative to the axis of the screw system. nut and which engages in a groove (521) formed at the end of a second arm (52) of the lever.

5. Device according to claim 4, characterized in that the pin (541) is mounted eccentrically, so as to adjust, by rotation of said pin on itself, the desired position of the corresponding lever (5) as a function of the angular position of the end of the screw-nut system that carries it.

6. Device according to claim 3, characterized in that the reversible screw-nut system (76, 77) comprises, at its end connected to the lever, a pinion (58) engaging with a toothed sector (59) made on the lever (5ι.

7. Device according to claim 3, characterized in that the nut (74) of the reversible nut screw system is fixed on the second bearing (74), and the screw (76) is rotatable, guided in rotation on the plate (41). ), and its end is connected to the lever (5).

8. Device according to claim 2, characterized in that the rotating assembly (4) comprises rotational connecting means (44) linking in rotation the plate (41) and the second bearing (74).

9. Device according to claim 8, characterized in that the connecting means in rotation comprise at least one pin (44) integral with the plate (41) and parallel to the main axis (Al) and sliding in a guide ring ( 75) of the second bearing (74).

10. Device according to claim 1, characterized in that the rotating assembly (4) is rotated by a motor (91) fixed to the frame and connected to the turntable by a belt (911).

11. Device according to claim 2, characterized in that the motor means for controlling the displacement in axial translation of the first bearing (73) comprise a motor (92) fixed on the frame (1) and the first bearing is driven in axial translation. by a set of racks (72) sliding parallel to the main axis (Al) and cooperating with pinions driven in rotation by said fixed motor (92).

12. Device according to claim 11, characterized in that the motor means for controlling the displacement in axial translation of the first bearing comprises a motor (92) fixed on the frame (1) and the first bearing is a toothed nut (85) having ur. internal thread engaged by screwing on a rocket (12) of the chassis centered on the main axis, the toothed nut (85) cooperating with a pinion (86) driven in rotation by said motor (92).

13. Device according to claim 3, characterized in that each tool (3) is rotated on its support lever (5) by a set of pulleys and belts (51, 62) connecting the tool (3). ) a drive roller (61) held in rolling contact with a fixed inner ring (13) integral with the frame (1). 15

14. Device according to claim 13 _r characterized in that the roller (61) is connected by a first belt (62) to an intermediate shaft (63) rotating in a bearing centered on the axis (A3)

Pivoting of the tool support lever (5), and the intermediate shaft (63) is connected to the tool (3) by a second belt (64).

15. Device according to claim 13, characterized in that the roller (61) is rotatably mounted on a roller support arm (6) pivotally mounted on the plate (41) along the pivot axis (A3) of the support lever. tool (5), so that the roller (61) is applied against the inner ring (13).

30

16- Device according to claim 3 _r characterized in that it comprises a rotary ring (81) rotatably mounted on the frame (1.) and driven in rotation by a third motor (93) fixed to the frame and a shaft

Intermediate (63 ') rotating in a bearing centered on the axis (A3) of pivoting of the tool support lever (5), and the intermediate shaft (63 ') is connected to the tool (3) by a set of pulleys and belts (83) and comprises a toothed wheel (82) cooperating with said rotary ring.

17. Process for producing parts, in particular elongated parts of revolution and of variable section in the longitudinal direction, by machining a bar

(B) held fixed in rotation, characterized in that a device according to any one of the preceding claims is used, the device and the bar are moved relative to each other, held fixed in rotation, in the direction of the main axis (Al ) and the bar is machined by the tools (3), according to a desired longitudinal and / or circumferential profile, by controlling, according to the desired profile, a radial displacement of the tools (3) as a function of the axial position of the bar relative to the frame and / or the circumferential position of the tools relative to the bar.

18. The method of claim 17, characterized in that the tools (3) are abrasive discs or discs with cutting teeth.