Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27C—PLANING, DRILLING, MILLING, TURNING OR UNIVERSAL MACHINES FOR WOOD OR SIMILAR MATERIAL
  • B27C7/00—Wood-turning machines; Equipment therefor
  • B27C7/005—Wood-turning machines; Equipment therefor by means of a rotating tool
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27C—PLANING, DRILLING, MILLING, TURNING OR UNIVERSAL MACHINES FOR WOOD OR SIMILAR MATERIAL
  • B27C5/00—Machines designed for producing special profiles or shaped work, e.g. by rotary cutters; Equipment therefor
  • B27C5/08—Rounding machines
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27L—REMOVING BARK OR VESTIGES OF BRANCHES; SPLITTING WOOD; MANUFACTURE OF VENEER, WOODEN STICKS, WOOD SHAVINGS, WOOD FIBRES OR WOOD POWDER
  • B27L9/00—Manufacture of wooden sticks, e.g. toothpicks
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T82/00—Turning
  • Y10T82/25—Lathe
  • Y10T82/2527—Lathe having hollow cutter head

Definitions

• 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.
• 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 elongate wooden parts in a main axial direction, in particular axisymmetric, from long wooden bars. 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.
• WO2010 / 046570 already discloses a method and a device for producing parts of revolution, or of a similar general shape, in particular of elongate and longitudinally variable wooden pieces in the longitudinal direction, which make it possible to machine, from straight or bent bars of any length held fixed in rotation, parts of sections both circular and axisymmetric any, and in a given longitudinal profile.
• This machining device makes it possible, among other things, to machine heavy and bulky parts such as profiled bars, beam columns and the like, obtained from bars made of machinable materials, such as hard or soft wood, or other materials.
• the device comprises a fixed frame carrying guide means for guiding said bar in translation along a main axis and maintaining it fixed in rotation, and a rotating assembly driven in rotation relative to the frame along the main axis.
• the rotating assembly comprises a plate and at least two rotary tools supported by pivoting arms relative to the plate in a plane orthogonal to the main axis. The tools are rotated along respective axes of rotation substantially parallel to the main axis.
• Means for controlling the position of the pivoting arms are provided for adjusting the radial positioning of the tools relative to the main axis.
• control means comprise motor means fixed to the frame 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 command said fixed motor means.
• the device uses a first system that converts a rotation of a fixed motor on the frame in an axial translation of a turntable, connected to the arms tool holder by a reversible nut screw system, which makes it possible to transform said axial translation into a pivoting of the arms.
• the first transformation of the rotation of the motor in axial translation is performed either by a rack-and-pinion system, or by a screw-nut system.
• One of the advantages of this device 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 according to a epicyclic type movement around said bar, and this by a device that does not require the use of embedded motors on rotating bodies.
• 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 any undesirable vibrations.
• the present invention therefore aims to provide a new system to ensure continuous radial positioning of the tools during the rotation of the plate, which is simpler to achieve, more reliable, requiring fewer moving mechanical parts.
• the subject of the invention is a process for 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 which relatively a frame relative to said bar, or vice versa, in a main direction corresponding to the longitudinal direction of the bar, and the bar is machined, according to a desired longitudinal and circumferential profile, by rotary tools carried by a main plate driven in rotation on the frame in a plane transverse to said axial direction, the tools being connected to the plate by radially movable tool supports on this plate, and, depending on said desired profile, a radial displacement of the tool supports in function is controlled the axial position of the bar relative to the frame and the circumferential position of the tools relative to the bar.
• the method is characterized in that, in order to control said radial displacement, a secondary plate is driven in rotation, coaxially with the main plate, comprising means for actuating the tool supports arranged in such a way that the position of the tool supports is a function of the relative angular position between the main plate and the secondary plate and, to adjust the positioning radial tools permanently during the rotation of the plate, modifies said relative angular position.
• each plate has its own rotation drive motor, and the modification of the relative angular position of the plates is achieved by a speed variation control of at least one of the motors, for example by means of electronic speed control means, which make it possible to ensure very fast and very precise speed variations.
• a computer controlling the motors according to a suitable program, predetermined according to the desired shapes of the circumferential and longitudinal profiles.
• the modification of the relative angular position of the trays is carried out by control means mechanical means varying the length of the strand tension of a belt or chain transmission used to transmit the rotation of an engine to at least one of the trays, more particularly the secondary tray.
• control means mechanical means varying the length of the strand tension of a belt or chain transmission used to transmit the rotation of an engine to at least one of the trays, more particularly the secondary tray.
• a single motor is used to drive the two trays by different belts, and the length of the stretched strand of one of the belts is varied by means of a pulley tensioner, whose position can be controlled by a cylinder or other suitable actuator.
• the modification of the relative angular position of the trays is performed by a dedicated motor mounted between a driving element of the main plate and the secondary plate.
• Another subject of the invention is a device intended for implementing the method indicated above, which comprises means for displacing a chassis in translation relative to the bar, or conversely, in a main direction corresponding to the longitudinal direction of the bar, and a rotating assembly driven in rotation relative to the frame along a main axis, the rotating assembly comprising a main 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 the device comprising means for controlling the position of the supports for adjusting the radial positioning of the tools relative to the main axis.
• the device is characterized in that said means for controlling the position of the tool supports comprise
• a secondary plate comprising means for actuating the tool supports arranged so that the position of the tool supports is a function of the relative angular position between the main plateau and the secondary plateau and
• said actuating means comprise main cams and the tool supports are connected to main fingers applied to said cams.
• the cams have a shape such that their radius is increasing over a predetermined angle corresponding to the maximum angular offset between the plates, and the amplitude of the radius variation is determined so as to generate a radial displacement of the tools of a desired maximum amplitude.
• the tool supports are arms mounted pivoting on the main plate and connected in rotation to the fingers resting on the cams.
• each main finger is constituted by an end of a lever pivotally connected to a tool support arm, the opposite end of the lever constituting a secondary finger resting on a secondary cam associated with the main cam on which the main finger is supported, the shapes and dimensions of the main and secondary cams and those of the lever being determined so that the secondary finger is in contact with the secondary cam when the main finger is in contact with the main cam, regardless of the position of the point of contact on the cam.
• the main finger is moved on the main cam and thus causes the pivoting of the tool support arm. More precisely, when the relative angular position between the trays varies in the direction leading to the main finger moving on the cam to a position of increasing radius, the tool is moved towards the axis of the rotating assembly. As a result, it is the main cam that supports the support of the main finger corresponding to the plunging force of the tool during machining.
• the cam and the secondary finger ensure the radial displacement of the tool in the opposite direction, that is to say outwards, when the relative angular position of the plates is varied in the opposite direction, the finger moving on the main cam to a position of decreasing radius.
• the finger and the secondary cam also make it possible to compensate for play between the fingers and the cams; for this purpose, the secondary finger is resiliently mounted on the end of the lever, for example by means of a pivoting rod and a return spring between the lever and said link.
• the secondary fingers which ensure the radial displacement of the tools in the direction of a distance from the main axis, it is the contact of the main fingers on the main cams which determines the radial position of said tools.
• the fingers will advantageously be in the form of rollers mounted rotating on the lever.
• the rotational drive of the tools is preferably provided by a fixed motor on the frame and transmitting its rotation via a rotating ring, the latter in turn driving by a belt pulleys with two grooves mounted in rotation on the pivot axes of the tool support arms, each of said pulleys rotating a tool by another belt extending along the tool support arm.
• the trays are rotated by one or more engines to which they are connected by pulleys and toothed belts or chains of in order to prevent any slippage of these transmission means between motors and trays.
• each plate has its own motor, and means for adjusting the speed of the motors are provided to be able to momentarily vary the speed of at least one of the motors so as to generate a variation of the angular offset between trays.
• one of the plates is rotated by a belt passing over a first translating pulley in translation over which the stretched strand of the belt passes; that is, the strand transmitting the rotational force, said first pulley being movable so as to be able to vary the length of the strand stretched.
• a variation in the length of this stretched strand during the rotation drive, at constant speed of the motor, generates a temporary variation in the speed of the driven plate, and therefore a relative angular offset with respect to its anterior position, this offset allowing to create the relative angular offset between the plates, if for example the other plate is maintained at a constant speed of rotation.
• the two plates are driven by the same motor, connected by a belt without sliding to the main plate and which therefore gives the rotational speed of the rotating assembly, and the secondary plate is connected to the same motor by a belt passing over the first return pulley.
• the return pulley for example by means of a cylinder controlled according to the profile of the desired machined part.
• a second idler pulley acting as a tensioner is mounted on the free end of the belt.
• the device comprises drive means for rotating the two plates by a same main motor, said drive means comprising an auxiliary motor mounted between the main motor and the secondary plate, and control means of the auxiliary motor for generating a variation of the angular offset between the plates.
• the auxiliary engine has for example its shaft connected in rotation with a drive shaft of the main motor and its stator connected to the secondary plate by a toothed belt.
• the auxiliary motor shaft is stationary in rotation relative to its stator, the two plates are fixed in rotation relative to each other.
• the auxiliary motor may be a stepper motor or any other motor unit mounted on a drive shaft of the main plate and adapted, alternatively, to rotate this drive shaft in solidarity with the secondary plate or to create a controlled angular offset between these.
• FIG. 1 represents a machining machine provided with a device according to the invention
• FIG. 2 is a simplified representation showing in particular the rotational drive of the tools
• FIG. 3 shows the arrangement of the motors on the frame of the device
• FIG. 4a is a perspective view showing the rotating assembly with the two plates, the tool support arms not being represented,
• FIG. 4b is a perspective view similar to that of FIG. 4a but having additionally removed the main plate to make it possible to see more clearly the system of cams and levers controlling the pivoting of the tool support arms,
• FIG. 5 is a schematic view illustrating the principle of the second embodiment
• FIG. 6 is a schematic view illustrating the principle of the third embodiment.
• the machining machine represented in FIG. 1 comprises a gantry 1 on which the machining device 2 is mounted, which comprises a frame 20 on which is mounted a rotating assembly 21 having a bore 22 in which the machined part 9 passes during of its machining.
• the rotating assembly 21 carries machining tools 3 driven in rotation and radially movable, so that the distance between the axis of rotation of the rotating assembly and the tools can be modified during the rotation of said rotating assembly. It is thus possible to vary the section of the machined part 9, when the latter is moved relative to the gantry in the direction of the arrow F, oriented substantially along the main axis A of rotation of the rotating assembly. Note that the part can be moved relative to the gantry remaining fixed, or the gantry moved, according to the arrow F ', relative to the piece held fixed.
• the main axis of rotation A may be oriented in the longitudinal direction of the part 9, or obliquely with respect to this direction.
• the rotating assembly 21 comprises a main plate 5 driven in rotation along the arrow Fl.
• arms 4 which are themselves pivotally mounted on the main plate 5 along axes B parallel to the main axis A, so as to be able to pivot according to the arrow F2 in a plane perpendicular to the axis A.
• each arm 4 is secured to a shaft 41 guided in rotation along the axis B in a bearing 54 of the plate 5.
• the main plate 5 is rotated by a motor 50 on the shaft of which is mounted a pulley 51 connected to the plate 5 by a belt 52.
• a secondary plate 6 is rotatably mounted, also along the main axis A, between the main plate and the frame 20.
• the secondary plate 6 is driven by a motor 60 a pulley 61 and a belt 62.
• the secondary plate 6 carries two cam assemblies 7, symmetrical about the axis A, on which support fingers constituted by rollers 43, 44 carried by the respective ends of levers 42 pivoting along the axes B and integral with the shafts 41.
• the levers 42 are therefore secured to the arms 4 in pivoting along the axes B.
• One of the rollers 43 is mounted at the end of a rigid arm 421 of the lever 42; the other roller 44 is mounted on a pivoting arm 422 of the lever 42.
• Each set of cams 7 comprises a main cam 71 and a secondary cam 72.
• the main cam 71 is arranged so that, when the secondary plate 6 rotates relative to the main plate 5 in the direction of the arrow F3 (see Figure 4) , the cam 71 pushes the roller 43, mounted on the rigid bottom 421 of the lever 42, radially outwardly, so as to pivot the lever, and therefore the arms 4, in the direction of the arrow F21, which direction also corresponds to a bringing of the tool 3 towards the axis main A.
• the cam 72 has a profile whose radius varies inversely to that of the main cam 71 so that when the secondary plate 6 carrying the cams 7 rotates relative to the main plate 5 carrying the levers, the roller 44 rolling on the cam 72 keeps the roller 43 in contact with the cam 71.
• the cam 72 pushes the roller 44 mounted on the pivoting bottom 422 of the lever 42, radially outwardly, so as to pivot the lever, and therefore the arms 4, in the opposite direction of the arrow F21, which direction also corresponds to a spacing of the tool 3 of the A.
• the arm 422 which is pivotally mounted on the lever 42 is also connected to said lever 42 by a spring 423, so as to ensure that the two rollers 43 and 44 are always in contact with the respective cams 71, 72, and thus ensure that there is at no time games between levers and cams may leave a pivotal freedom to the tool arm 4.
• a spring 423 so as to ensure that the two rollers 43 and 44 are always in contact with the respective cams 71, 72, and thus ensure that there is at no time games between levers and cams may leave a pivotal freedom to the tool arm 4.
• the machining radius can be varied rapidly, and thus not only machining a part with any longitudinal profile, within the limit well sure of the maximum movement of the tools, but also machining a workpiece with a variable radius in the same section orthogonal to the main axis.
• This latter possibility makes it possible in particular to machine parts of polygonal section, in particular square or rectangular, oval, and as well as parts of helical shape for example, or generally any part whose envelope, that is to say say the volume form, is defined by a cross section whose shape and area may vary in the longitudinal direction of the part.
• the speed control of the motors 50 and 60 may be of any type adapted to ensure the greatest possible accuracy of the relative speed variations, in particular by electronic control.
• stops 55 are fixed on the main plate, so as to block the movement of the cams.
• FIG. 4b does not show the plate 5
• the stops 55 are shown to illustrate their function of limiting the pivoting of the plate 6 with respect to the plate 5.
• the rotational drive of the tools 3 is carried out as follows:
• a motor 30 rotates, by a toothed belt 31, an inner ring 32 rotatable along the main axis A, the inner cylindrical wall defines the bore 22 allowing the passage of the workpiece.
• the front end of the ring 32 comprises a toothed pulley groove 321 which receives a toothed belt 33 passing over one of the grooves of two pulleys with two grooves 34 rotatably mounted on the shafts 41 of pivoting axes B of the arms 4, as shown in FIG. 2.
• the second grooves of the pulleys 34 are connected to the tools 3 by a belt 35.
• the tools 3 are rotated by the motor 30 mounted in a fixed position on the frame 20, and their rotational speed can be adjusted directly by a speed controller of the motor 30.
• a speed controller of the motor 30 of the motor 30.
• part of the rotational drive of the tools results directly from the drive in rotation of the trays.
• the motor 30, and therefore the inner ring 32 are immobilized in rotation, the rotation of the plate 5 causes a rotation of the pulleys with two grooves 34 on their axes B, and therefore a rotation of the tools.
• the motor 20 makes it possible, by rotating the ring 32 in the opposite direction (arrow F4) of the rotation of the plate 5, as shown in FIG. 2, to increase the speed of rotation of the tools which would result from the only rotation of the plate 5, and the motor 20 also makes it possible to adjust the effective rotational speed of the tools, independently of that of the plate.
• FIG. 5 diagrammatically represents another embodiment making it possible to control the relative angular offset of the plates 5 and 6.
• the main plate 5 is rotated directly by a motor 59 carrying a drive pulley 51, via the belt 52.
• the motor shaft 59 carries a second pulley 68, rotating the secondary plate 6 via the belt 69.
• the reduction ratios of the drives of the two trays are the same to ensure steady state, the same speed of rotation of the two trays.
• the drive belt 69 of the secondary plate 6 passes over a set of return pulleys comprising in particular two pulleys 81, 82 rotatably mounted on the same slide 83 whose sliding, transverse to the general direction of travel of the belt 69, is controlled by a cylinder 84.
• the other pulleys 85 are fixed.
• the displacement of the pulley 81 located on the stretched strand 691 of the belt 69 causes a variation in length of this stretched strand and therefore an angular offset between the two plates.
• the variation in length of the stretched strand is compensated by an inverse length variation of the free strand 692, authorized and controlled by the displacement of the pulley 82, simultaneously with that of the pulley 81, the pulley 82 thus acting in the manner of a belt tensioner to compensate for variations in length of the stretched strand.
• FIG. 6 schematically represents yet another embodiment making it possible to control the relative angular offset of the plates 5 and 6.
• the device comprises drive means 90 for rotating the two plates 5, 6 by one and the same.
• main motor 91 via a main drive shaft 92.
• the main plate 5 is driven from this main shaft by a connection without sliding, for example by a toothed belt 931 passing on a pulley 932 integral with the shaft 92.
• the speed of rotation of the plate 5 can therefore be adjusted by adjusting the speed of the motor 91.
• the secondary plate 6 is driven from this main shaft 92 via an on-board auxiliary engine 94, the rotor 941 of which is rotatably connected to the shaft 92.
• the stator housing 942 of the engine 94 carries a pulley 943 which drives the secondary plate 6 by a non-slip connection, for example by toothed belt 944.
• the ratio of the diameters of the pulley 932 and the plate 5 is the same as that of the pulley 941 and the plate 6, so that the two plates 5 and 6 rotate at the same angular speed if the pulleys 932 and 943 also rotate at the same speed.
• the motor 94 is powered by a regulator via a rotary electrical collector 945, which makes it possible to precisely control the speed and the angular position between the rotor and the stator.
• the motor 90 In steady state, without variation of the machining radius, the motor 90 is not powered and its stator and its rotor are fixed in relative rotation. Both trays 5 and 6 are driven at exactly the same speed.
• it is sufficient to control a rotation of the motor 94, which will cause an angular offset of the plates 5 and 6, and thus a pivoting of the tool arms as previously indicated.
• the invention is not limited to the examples described above and encompasses all the variants of systems making it possible to ensure a controlled relative angular offset between the two plates 5 and 6 during the rotation thereof.
• the rotation drive system of the tools can be modified.
• the tool arms may also be curved, with a concavity oriented towards the main axis, so as to avoid any risk of contact between the arm and the workpiece, for example at the angles when machining parts having a square or rectangular section.
• the arms 4 may also be made in two parts, adjustable in angular position relative to each other, for example along the axis B, so as to allow fine adjustment, with an accuracy of 0.05 mm, the radial position, relative to the axis A, of each tool, independently of one another. This makes it possible to ensure the equidistance of the tools relative to the main axis of the machine, and thus allows precise and identical machining by the two tools.

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• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Wood Science & Technology (AREA)
• Forests & Forestry (AREA)
• Manufacturing & Machinery (AREA)
• Transmission Devices (AREA)
• Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
• Turning (AREA)
• Grinding And Polishing Of Tertiary Curved Surfaces And Surfaces With Complex Shapes (AREA)

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• 2011
  • 2011-03-18 FR FR1152237A patent/FR2972670B1/fr not_active Expired - Fee Related
• 2012
  • 2012-03-15 EP EP12714781.7A patent/EP2686149B1/de not_active Not-in-force
  • 2012-03-15 US US14/005,355 patent/US20140000762A1/en not_active Abandoned
  • 2012-03-15 WO PCT/FR2012/050538 patent/WO2012127153A2/fr not_active Ceased
  • 2012-03-15 CA CA2829077A patent/CA2829077A1/fr not_active Abandoned

Non-Patent Citations (1)

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