Numerically-controlled machine tool comprising multi-spindle turret and tool clamping device

Abstract

The invention relates to a numerical control machine tool comprising a multi-spindle turret and a tool clamping device. The invention relates to a numerically-controlled machine tool comprising a multi-spindle turret provided with a body extending along an axis A-A between a first end through which the body is fastened to a frame of the machine tool and a second end at which the body comprises a rotatable head, the head comprises at least two tool-holding spindles each intended to receive a cutting tool in an engaged manner, the spindles occupying, depending on the head angular position, a working position in which they are intended to perform a machining operation on the workpiece held in position in the fixture, or a standby position in which they are withdrawn from the workpiece, each spindle is configured to be controlled independently of the other spindles to fixedly or rotatably drive its carried tools regardless of its occupied position, the machine tool further comprising a tool holding device configured to take out the tools carried by the spindles in a standby position for its storage and to insert replacement tools into the spindles.

Description

Technical Field

[0001] The invention relates to the field of numerically controlled machine tools for machining workpieces, preferably micromechanical workpieces, and to the field of devices for such machines.

[0002] More specifically, the present invention relates to a numerically controlled machine tool including a multi-spindle turret and a tool holding device. Background Art

[0003] CNC machine tools are designed to produce mass-produced parts following the instructions of a computer program, particularly by machining. These machines include a tool mounted in a tool holding spindle and are usually equipped with a tool changing device to exchange the tool held by the tool holding spindle so as to adapt it to the machining operation to be performed on a workpiece held in place in a fixture.

[0004] During a tool change, the machine is no longer productive, which means that the machining operation is interrupted. The aim is therefore to minimize the time required to change the tool. For this purpose, tool changers have been developed to work as much as possible in parallel with the machining operation and to minimize machine downtime in order to increase its productivity.

[0005] For example, multi-spindle turrets are known that include a head on which a plurality of tool holding spindles are arranged, one of which is in motion and the others are stationary. In particular, the in motion tool holding spindle is coupled to a drive mechanism by means of a coupling system. Thus, between two machining operations, the tool can be changed by disengaging the in motion tool holding spindle, i.e. the spindle carrying the tool to be changed, rotating the head in order to present the next tool holding spindle, and coupling this tool holding spindle to the drive mechanism.

[0006] However, this solution is not completely satisfactory, since, although the tool change time is reduced, it is not performed completely simultaneously with the machining operation. More specifically, between each tool change, with this type of multi-spindle turret, the tool to be changed must be braked before the tool change is performed, and once the next tool is coupled to the drive mechanism, it must be accelerated until it reaches its rotational machining speed. These multi-spindle turrets also require a certain amount of time to unclamp the tool to be changed, pivot the head and index the next tool so that it is aligned with the coupling system and then perform the coupling. Due to the coupling system, this solution is also particularly complex and expensive.

[0007] Multi-spindle turrets solve the problem of accelerating and braking tool holding spindles, where the tools are all driven rotatably and synchronously. Thus, when changing a tool, the next tool is already driven at its rotational machining speed and can start machining the workpiece. However, these multi-spindle turrets require a lot of energy to rotate all the tools simultaneously. Moreover, due to the motion transmission kinematic chain, the maximum rotational speed of the tools they carry is relatively limited.

[0008] In general, prior art multi-spindle turrets are bulky, whether they rotate the tools they carry individually or simultaneously, which creates a large moment of inertia and increases the risk of collision between the fixture and the tools carried by the turret.

[0009] Besides the above mentioned disadvantages, it is to be understood that these solutions are also not suitable for machining micromechanical workpieces. Summary of the invention

[0010] The present invention overcomes the aforementioned drawbacks by providing a solution that allows the tool to be changed and replaced completely simultaneously with the machining operation, in particular by performing the tool acceleration and deceleration phases simultaneously with the machining operation, and by engaging the multi-spindle turret with the tool holding device simultaneously with the machining operation.

[0011] To this end, the invention relates to a numerically controlled machine tool comprising a multi-spindle turret provided with a body extending along an axis AA between a first end, by which the body is fastened to the frame of the machine tool, and a second end, at which the body comprises a rotatable head. The head comprises at least two tool-holding spindles, each of which is intended to receive in engagement a cutting tool, said spindles occupying either a working position, in which they are intended to perform a machining operation on a workpiece held in position in a fixture, or a standby position, according to the angular position of the head, in which they are intended to perform a machining operation on a workpiece held in position in a fixture, or in which they are withdrawn from said workpiece. Each spindle is configured to be controlled independently of the other spindles, so as to drive the tool it carries, either fixedly or rotatably, regardless of the position occupied by the spindle. The machine tool also comprises a tool-holding device configured to interact with a spindle in the standby position, in order to remove the tool carried by said spindle for its storage, and to insert a replacement tool into said spindle.

[0012] Since the spindles are independently controlled, they can be accelerated and decelerated simultaneously with the machining operation. The invention thus allows the non-productive time for changing tools to be reduced to the duration of the head rotation until the next tool comes into contact with the workpiece, while making it possible to replace the tool on the spindle in a standby position simultaneously with the machining operation.

[0013] In particular embodiments, the invention may also comprise one or more of the following characteristics, which have to be considered individually or in any technically possible combination.

[0014] In a particular embodiment, the clamping device comprises a tool holder held in a cantilevered position by a support structure fastened to the body of the turret. The tool holder comprises a storage bucket with rotational freedom about an axis CC.

[0015] In a particular embodiment, the seat is configured such that the axis CC is parallel to the longitudinal axis B'-B' or B"-B" of the spindle interacting therewith, the drum and the spindle being translatable relative to each other along the axis CC.

[0016] In a particular embodiment, the seat has at least one degree of freedom in translation or rotation, allowing it to move between the following positions:

[0017] an active position, in which the tool holder is in the immediate vicinity of the spindle with which it is configured to interact, and

[0018] A disengaged position in which the seat is further away from the axis AA than when it is in the operative position.

[0019] In a particular embodiment, the support structure comprises a coupling member fastened to the body of the turret and connected to the knife holder by an arm configured to move the knife holder between its operating position and its disengaged position.

[0020] In a particular embodiment, the arm has a distal portion fastened to the seat, the distal portion being connected by a slide or a pivot to a proximal portion fastened to the coupling member.

[0021] In a particular embodiment, the machine tool comprises at least two spindles occupying a standby position, the coupling member being fastened to the body of the turret so as to be rotatable about axis AA in order to drive a tool holder from one spindle occupying a standby position to another.

[0022] In a particular embodiment, the tool holder has a certain degree of translational mobility relative to the coupling member along an axis parallel to the axis AA, so as to move the tool holder further away from the turret head when it occupies the disengaged position.

[0023] In a particular embodiment, the coupling member is fastened to the body of the turret so that it can slide along axis AA in order to move the seat further away from the head of the turret when the seat occupies the disengaged position.

[0024] In a particular embodiment, the tool holder comprises a protective shell provided with a notch comprising an axial portion and a radial portion allowing both the spindle and the tool to be stored to be inserted into the tool holder and allowing the tool holder to be detached if the tool has been replaced.

[0025] In a particular embodiment, a radial portion of the notch is shaped to match the shape of the spindle when the tool is replaced. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Other characteristics and advantages of the present invention will become apparent from the following detailed description, given by way of example and in no way limiting, with reference to the accompanying drawings, in which:

[0027] - Figure 1 shows a perspective view of a multi-spindle turret according to a preferred exemplary embodiment of the present invention, wherein a tool holding device is capable of replacing a tool carried by one or more spindles of the turret;

[0028] - Figure 2 The longitudinal axis of the main body of the turret is shown. Figure 1 The view of the turret shown in ;

[0029] - Figure 3 Shown is a small tool holder Figure 1 , which reveals a certain degree of possible movability of the tool holding device.

[0030] It should be noted that for the sake of clarity, the drawings are not necessarily drawn to scale. DETAILED DESCRIPTION

[0031] The present invention relates to a numerically controlled machine tool 10, such as Figure 1 As shown in FIG. 1 , it comprises a multi-spindle turret 20 and a tool holding device 30 for machining preferably micromechanical workpieces.

[0032] In the exemplary embodiment of the invention shown in the accompanying drawings, the turret 20 comprises a body 21 extending along a longitudinal axis, referred to as the “AA axis”, the body 21 comprising at one end a base 22 for fastening to the frame 11 of the machine tool 10, and at the other end a head 23 rotatable about an axis coinciding with the axis AA.

[0033] The head 23 comprises at least two tool-holding spindles 24, 24' or 24", each of which is intended to engage a tool 25, 25' or 25". Depending on the angular position of the head 23, each spindle 24, 24' and 24" occupies a working position in which it is intended to perform a machining operation on a workpiece held in position in a fixture, or a standby position in which it is withdrawn from the workpiece. Figures 1 to 3 In the embodiment, the turret 20 comprises three spindles 24, 24' and 24", one of which is in the working position and two of which are in the standby position. It should be understood that the rotation of the head 23 causes the tool to be changed, the tool 25 occupying the working position is moved to the standby position, and one of the tools 25' or 25" in the standby position is moved to the working position.

[0034] It should be noted that the turret 20 can be driven translationally, for example, in a case where the base 22 is fastened to a carriage (not shown) of the machine tool 10, the carriage being movable with at least one translational degree of freedom, preferably with three translational degrees of freedom, relative to the XYZ trihedron.

[0035] Alternatively, the turret 20 may be stationary, for example in the case where the base 22 is fastened directly to the frame 11 of the machine tool 10. The fixture is thus provided with the aforementioned degrees of freedom, for example three degrees of freedom in translation along the directions X, Y and Z, respectively, and optionally one or two degrees of freedom in rotation about X and / or Y.

[0036] The spindles 24, 24' and 24" are advantageously configured so that they can be controlled independently of one another in order to rotate or fix the tool 25, 25' or 25" carried by them. This feature is particularly advantageous when changing the tool. Preferably, the spindles 24, 24' and 24" are motorized spindles, also called "electric spindles", and each includes its own motor for rotating or fixing the tool 25, 25' or 25" carried by it.

[0037] In particular, in order to replace the first tool 25 performing a first machining phase with a second tool 25 ′ or 25 ″ intended to perform a second machining phase, before the end of the first machining phase, the latter is rotatably driven until it reaches a rotation speed specific to the second machining phase.

[0038] The first tool 25 is engaged in the spindle 24 in the working position and the second tool 25 ′ or 25 ″ is engaged in one of the spindles 24 ′ or 24 ″ in the standby position.

[0039] As soon as the first machining phase is completed, the head 23 is pivoted so as to drive the spindle 24 in the working position into the standby position and the spindle 24' or 24" in the standby position into the working position. The second machining phase then begins immediately due to the fact that the second tool 25' or 25" reaches its rotational machining speed while the spindle 24' or 24" to which it is engaged is in the standby position. With the spindle 24 carrying the first tool 25 now in the standby position, its rotational movement stops.

[0040] Thus, when the second tool 25 ′ or 25 ″ rotates and the first tool 25 stops rotating simultaneously with the machining operation, the non-productive time of the tool change is reduced only to the duration of the rotation of the head 23 along the axis AA.

[0041] Each spindle 24, 24' and 24" extends along a longitudinal axis, respectively, which is called "axis BB", "axis B'-B'" and "axis B"-B"", and the above axes also constitute their rotation axes. Figure 1 As shown in Figure 1 and Figure 3 As can be seen in FIG. 2 , in the working position, the spindle 24 is preferably oriented so that its axis BB is parallel to the vertical axis.

[0042] Advantageously, the invention makes it possible to replace, during the execution of a machining operation, a tool 25' or 25" to be stored, carried by one of the spindles 24' or 24" that is in standby position and does not rotate. More specifically, the machine tool 10 comprises a tool holding device 30 capable of removing a tool 25' or 25" to be stored from a spindle 24' or 24" and inserting a new tool, referred to as a "replacement tool" 25'"', into said spindle 24' or 24", as described below.

[0043] The clamping device 30 is fastened to the body 21 of the turret 20, such as Figures 1 to 3 As shown in , for example, in the case where the base 22 is fastened to a carriage that is movable relative to the frame 11 .

[0044] As from Figures 1 to 3 As can be seen, the clamping device 30 comprises a tool magazine 34 held in a cantilevered manner by a support structure 31. The tool magazine 34 comprises a tool storage bucket 340, which comprises a plurality of recesses 341, which are intended to receive replacement tools 25"' or replaced tools. In particular, the recesses 341 may each comprise a radially open opening through which they can engageably receive replacement tools 25"' or replaced tools.

[0045] In this example, the storage tub 340 may take the form of a disk having recesses 341 evenly distributed around its periphery.

[0046] Each recess 341 may include a clamping member formed by a clamp 342, which Figure 2 . Each clamp 342 has elastic deformation properties so that it can receive the tool in engagement and hold it in place in the recess 341 by friction. In particular, the tool may include an annular groove 250 in which the clamp 342 is intended to engage. It should be noted that such elastic clamps are known to those skilled in the art and their design is within their capabilities.

[0047] exist Figures 1 to 3 In the exemplary embodiment of the invention shown in , the storage barrel 340 has a degree of freedom of rotation about an axis CC parallel to the axis B'-B' or axis B"-B" of one of the spindles 24' or 24" in the standby position, in particular the spindle 24' interacting therewith, so as to be able to face each recess 341 it includes towards said spindle 24'. This degree of freedom is determined by Figure 3 Indicated by arrow 40 in FIG.

[0048] The storage barrel 340 and the spindle 24' interacting therewith can also be moved translationally relative to each other along an axis parallel to the axis B'-B' of the spindle 24'. This relative mobility is preferably ensured by the translational freedom of the storage barrel 340 along the axis CC, such as Figure 3 As indicated by arrow 41 in FIG. Alternatively, this relative mobility can be ensured by the freedom of translation of the spindle 24 ′ in the standby position along the axis B′-B′.

[0049] More specifically, in order to replace the tool 25' engaged in the spindle 24' in the standby position with a replacement tool 25''' arranged in the storage barrel 340, the latter is pivoted so that the empty recess 341 faces the tool 25' to be stored, and then the storage barrel 340 is moved translationally toward the spindle 24' so that the tool 25' to be stored is inserted into the recess 341. During the insertion of the tool 25' to be stored into the recess 341, its clamp 342 is deformed, Until it engages in the annular groove 250 of the tool 25' to be stored. Then, translation of the storage barrel 340 in the direction opposite to the main shaft 24' allows the tool 25' to be removed for storage. In order to insert a replacement tool 25'' into the main shaft 24', the storage barrel 340 is pivoted until the replacement tool 25'' is aligned with the main shaft 24' and then translated toward the main shaft 24' so as to engage the replacement tool 25'' in the main shaft 24'. The translation movement in a direction perpendicular to the axis B'-B' allows the replacement tool 25'' to be removed from the recess 341 in which it is located, and the replacement tool 25'' is now secured in the main shaft 24'.

[0050] It should be noted that if the recess 341 is arranged so that its opening is open tangentially or orthoradially relative to the storage barrel 340, the tool 25' to be stored is engaged in the recess 341 and the replacement tool 25'' is removed from the recess 341 by rotating the storage barrel 340 along the axis CC in two opposite directions respectively.

[0051] In a manner known per se to a person skilled in the art, during these operations, the spindle 24' is controlled so as to release the tool 25' to be stored when the storage barrel 340 is movable translationally in a direction opposite to the spindle 24' and is configured to lock the replacement tool 25'' when the replacement tool 25'' is inserted therein.

[0052] Advantageously, the tool holder 34 may have one or more degrees of freedom in translation or rotation, allowing it to be moved between an operating position and a disengaged position. In the operating position, the tool holder 34 is in the immediate vicinity of a spindle 24' or 24", in particular a spindle 24', which is in a standby position, with which the tool holder 34 is intended to interact in order to remove a tool 25' to be stored, which tool is carried by it, or to insert a replacement tool 25''' into said spindle 24', as previously described. In the disengaged position, the tool holder 34 is further away from the axis AA, and therefore further away from the head 23, than when it is in the operating position. Such an arrangement prevents any risk of collision of the tool holder 34 during a machining operation or when the head 23 is rotated to change a tool.

[0053] To this end, the support structure 31 is configured to move the blade holder 34 between its operating position and its disengaged position.

[0054] In particular, if Figures 1 to 3 As shown in , the support structure 31 may include a coupling member 32, which is fastened to the body 21 of the turret 20 and is connected to a tool holder 34 via an arm 33. The arm 33 is configured to move the tool holder 34 between its operating position and its disengaged position. In particular, the arm 33 may be configured to move the tool holder 34 translationally along an axis substantially orthogonal to the axis B'-B' of the spindle 24' in the standby position, with which the tool holder 34 interacts, as shown in FIG. Figure 3 As shown by arrow 42 in FIG.

[0055] In this exemplary embodiment, the degree of translational mobility of the tool holder 34 along an axis substantially orthogonal to the axis B'-B' of the main shaft 24' is provided by a distal portion 330 of the arm 33, which is fastened to the tool holder 34 and is connected by a slide to a proximal portion 331 fastened to the connecting member 32.

[0056] Alternatively, in an exemplary embodiment not shown in the drawings, in order to move it between one and the other of its operating and disengaged positions, the knife holder 34 can be pivoted relative to the arm 33 about an axis of rotation parallel to the axis B'-B' of the spindle 24' intended to interact with it, the distal portion 330 thus being pivotally connected to the proximal portion 331. It is to be understood here that the knife holder is rotated in such a way that the storage barrel 340 is driven eccentrically so as to move it away from or towards the spindle 24' intended to interact with it.

[0057] Preferably, the coupling member 32 is formed by a fastening ring arranged around the body 21 and fastened to the body 21 so as to be rotatable about the axis AA, as shown in FIG. Figure 3 44 in FIG. 4 . The shape of the fastening ring allows the forces involved to be advantageously distributed. This mobility makes it possible to move the tool holder 34 so as to interact successively with all the spindles 24 ′ and 24 ″ occupying the standby position and, therefore, to replace the tools 25 ′ and 25 ″ of these spindles without rotating the head 23 of the turret 20.

[0058] Advantageously, by means of the arm 33, the knife seat 34 can have a certain degree of translational mobility relative to the coupling member 32 along an axis parallel to the axis AA, so as to move the knife seat 34 further away from the head 23 when it is in the disengaged position. In particular, if Figure 3 As illustrated by arrow 43 in FIG. 4 , a proximal portion 331 of the arm 33 may be secured to the coupling member 32 so as to be movable in translation along an axis parallel to the axis AA.

[0059] Alternatively, the coupling member 32 may be fastened to the body 21 of the turret 20 such that it is slidable along the axis AA.

[0060] In an exemplary embodiment of the invention in which the turret is stationary relative to the frame 11, the fixture has a degree of translational and rotational mobility suitable for executing a machining program.

[0061] Advantageously, as in Figures 1 to 3 As can be seen in the drawings, the tool holder 34 comprises a protective shell 35, which in these figures is shown in the form of a rigid wall having an axisymmetric shape. Due to the kinematics described above, the protective shell 35 comprises a slot 350 through which a tool 25', 25" or 25"' can pass when the tool holder 34 moves.

[0062] In particular, the slot 350 comprises an axial portion and a radial portion, thereby allowing both the spindle 24' and the tool 25' to be stored to be inserted into the tool holder 34, and allowing the tool holder 34 to be detached in the event that the tool 25' or 25" has been replaced. Advantageously, the radial portion of the slot 350 is shaped to match the shape of the spindle 24' when the tool 25' or 25" is replaced.

[0063] More generally, it should be noted that the embodiments and examples considered above are described by way of non-limiting examples and that other alternatives are therefore possible.

Claims

1. A numerically controlled machine tool (10), characterized in that: The numerically controlled machine tool (10) comprises a multi-spindle turret (20) provided with a body (21) extending along an axis AA between a first end and a second end, by means of which the body (21) is fastened to a frame (11) of the machine tool (10), and at the second end the body (21) comprises a rotatable head (23), the head (23) comprising at least two tool holding spindles (24, 24', 24"), each of which is intended to receive in engagement a cutting tool (25, 25', 25"), the spindles (24, 24', 24") occupying, depending on the angular position of the head (23), either a working position in which they are intended to perform a machining operation on a workpiece held in position in a fixture, or a standby position in which they are withdrawn from the workpiece, the spindles (24, 24', 24") being arranged to move the tool in a direction of rotation relative to the workpiece. Each of the spindles (24', 24") is configured to be controlled independently of the other spindles so as to drive the tool (25, 25', 25") carried by it fixedly or rotatably, regardless of the position occupied by the spindle, the machine tool (10) also comprising a tool holding device (30) configured to interact with the spindle (24', 24") in a standby position so as to remove the tool (25', 25") carried by the spindle (24', 24") for its storage and to insert a replacement tool (25'") into the spindle (24', 24"), the holding device (30) comprising a tool holder (34) held in a cantilevered position by a support structure (31) fastened to the body (21) of the turret (20), the tool holder (34) comprising a storage bucket (340) having a rotational degree of freedom about an axis CC.

2. The machine tool (10) according to claim 1, wherein: The tool holder (34) is configured such that the axis CC is parallel to the longitudinal axis B'-B' or B"-B" of the spindle (24', 24") in the standby position interacting with the tool holder (34), and the storage barrel (340) and the spindle (24', 24") are capable of translating relative to each other along the axis CC.

3. The machine tool (10) according to claim 1 or 2, wherein: The knife seat (34) has at least one degree of translational or rotational freedom, thereby allowing the knife seat (34) to move between the following positions: an operating position in which the tool holder (34) is in close proximity to the spindle (24', 24") with which it is configured to interact, and a disengaged position in which the blade seat (34) is further away from the axis AA than when it is in the operating position.

4. The machine tool (10) according to claim 3, wherein: The support structure (31) comprises a coupling member (32) which is fastened to the body (21) of the turret (20) and is connected to the knife seat (34) by an arm (33) which is configured to move the knife seat (34) between its operating position and its disengaged position.

5. The machine tool (10) according to claim 4, wherein: The arm (33) has a distal portion (330) fastened to the blade seat (34), and the distal portion (330) is connected to a proximal portion (331) fastened to the coupling member (32) by a slide or a pivot.

6. The machine tool (10) according to claim 4 or 5, comprising at least two spindles (24', 24") occupying a standby position, the coupling member (32) being fastened to the body (21) of the turret (20) so as to be rotatable about the axis AA in order to drive the tool holder (34) from one of the spindles (24', 24") occupying the standby position to the other.

7. The machine tool (10) according to claim 4 or 5, wherein: The tool holder (34) has a certain degree of translational mobility relative to the coupling member (32) along an axis parallel to the axis AA, so as to move the tool holder further away from the turret head when it occupies the disengaged position.

8. The machine tool (10) according to claim 4 or 5, wherein: The coupling member (32) is fastened to the body (21) of the turret (20) so as to be able to slide along the axis AA in order to move the tool holder further away from the head of the turret when the tool holder occupies the disengaged position.

9. The machine tool (10) according to claim 1 or 2, wherein: The tool holder (34) comprises a protective shell (35) provided with a notch (350) comprising an axial portion and a radial portion, thereby allowing both the spindle (24', 24") and the tool (25', 25") to be stored to be inserted into the tool holder (34), and allowing the tool holder (34) to be detached when the tool (25', 25") has been replaced.

10. The machine tool (10) according to claim 9, wherein: The radial portion of the notch (350) is shaped to match the shape of the spindle (24', 24") when the tool (25', 25") is replaced.

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