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

Abstract

To change and replace tools entirely concurrently with machining operations.SOLUTION: A multi-spindle turret for a numerically controlled machine tool includes at least two tool-holding spindles and carries out machining operations by tools carried by the spindles. Further, a tool gripping device is provided, the tool gripping device configured to interact with a spindle in a standby position in order to extract a tool carried by the spindle for the storage thereof, and in order to insert a replacement tool into the spindle.SELECTED DRAWING: Figure 1

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 equipment for such machine tools.

[0002] In particular, the present invention relates to a numerically controlled machine tool with a multi-spindle turret and a tool gripping device. [Background technology]

[0003] Numerically controlled machine tools are intended to produce mass-produced parts, particularly by machining, according to the instructions of a computer program. Such machine tools have tools mounted on tool-holding spindles and are usually equipped with a tool changer for replacing the tools held by the tool-holding spindles to suit machining operations to be performed on a workpiece held in place in a fixture.

[0004] During tool change, the machine tool cannot produce and machining operations are interrupted. In these situations, the goal has been to minimize the time required for tool change. For this reason, tool changers have been developed to operate as concurrently as possible with machining operations, minimizing machine downtime and increasing productivity.

[0005] For example, multi-spindle turrets are known in which there is a head in which several tool-holding spindles are arranged, one of which is active and the others are idle. In particular, the active tool-holding spindle is engaged with the drive mechanism by means of a coupling system. Thus, between two machining operations, the tool can be changed by disengaging the active tool-holding spindle, i.e. the spindle carrying the tool to be changed, rotating the head towards the next tool-holding spindle and coupling this tool-holding spindle to the drive mechanism.

[0006] However, this approach is not entirely satisfactory in that, although the tool change time is reduced, it is not completely simultaneous with the machining operation. In particular, in this type of multi-spindle turret, during each tool change, the tool to be changed must be braked before the tool change is performed, and the next tool must be accelerated to the machining rotation speed after it is coupled to the drive mechanism. Also, in such a multi-spindle turret, some time is required to disconnect the tool to be changed, rotate the head to index the next tool, align it with the coupling system, and couple it. Moreover, this approach is particularly complex and expensive due to the coupling system.

[0007] In a multi-spindle turret, the tools are all driven in rotation synchronously, solving the problem of accelerating and braking the tool-holding spindle. Thus, when a tool is replaced, the next tool is already driven at its processing rotation speed and can begin processing the workpiece. However, such a multi-spindle turret requires a large amount of energy to rotate all the tools simultaneously. Also, the maximum rotation speed of the tools carried by such a multi-spindle turret is relatively limited due to the kinematic chain that transmits the motion.

[0008] Overall, whether the tools it carries are rotated individually or simultaneously, prior art multi-spindle turrets are bulky, which results in a high moment of inertia and an increased risk of collision between the fixtures and tools carried by the turret.

[0009] In addition to the above challenges, such techniques are believed to be unsuitable for machining micromechanical workpieces. Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention solves this problem by providing a technique that allows a tool to be changed completely simultaneously with the machining operation, in particular by performing the acceleration and deceleration phases of the tool simultaneously with the machining operation, and by engaging a multi-spindle turret with a tool gripping device simultaneously with the machining operation. [Means for solving the problem]

[0011] To this end, the invention relates to a numerically controlled machine tool comprising a multi-spindle turret with a body extending along an axis AA between a first end fixed to a frame of the machine tool and a second end at which a rotatable head is located, and at which there are at least two tool-holding spindles, each of which is intended to engage and receive a cutting tool, and which, depending on the angular position of the head, occupy a work position intended to perform a machining operation on a workpiece held in a given position in a fixture and a standby position disengaged from said workpiece, each spindle being adapted to be controlled independently of the other spindles in order to immobilize or to rotate drive the tool it carries, regardless of the position it occupies, and the machine tool further comprises a tool-gripping device adapted to interact with a spindle in its standby position in order to extract the tool carried by said spindle for storage and to insert a replacement tool into said spindle.

[0012] Because the spindles are controlled independently of each other, they can be accelerated and decelerated simultaneously with the machining operation. Thus, the invention allows tools to be changed simultaneously with the machining operation, with the spindle in a standby position, while reducing the non-productive time for changing tools to only the duration of the head rotation until the next tool contacts the workpiece.

[0013] In particular embodiments, the invention may further comprise one or more of the following features, which must be considered alone or according to any combination technically possible:

[0014] In a particular embodiment, the tool gripping device comprises a tool magazine held in a cantilevered position by a support structure fixed to the body of the turret, the magazine comprising a storage barrel with a rotational degree of freedom about an axis CC.

[0015] In a particular embodiment, the magazine is configured such that the axis CC is parallel to the main axis B'-B' or B"-B" of the interacting spindle, and the storage barrel and the spindle are mutually translatable along the axis CC.

[0016] In certain embodiments, the magazine has at least one translational or rotational degree of freedom that allows it to move between an active position where it is in close proximity to a spindle with which it is configured to interact, and a disengaged position where it is further away from the axis AA than it is in the active position.

[0017] In a particular embodiment, the support structure includes a coupling member secured to the body of the turret and connected to the magazine by an arm configured to move the magazine between an active position and a disengaged position.

[0018] In certain embodiments, the arm has a distal portion secured to the magazine that is slidably or pivotally connected to a proximal portion secured to the connecting member.

[0019] In a particular embodiment, the at least two standby positions are occupied and the connecting member is rotatably fixed to the body of the turret about the axis AA to move the magazine from one spindle occupying a standby position to another spindle.

[0020] In certain embodiments, the magazine further has translational mobility relative to the coupling member along an axis parallel to the axis AA, thereby moving the magazine away from the head of the turret when the magazine is in a disengaged position.

[0021] In certain embodiments, the connecting member is secured to the body of the turret so as to be slidable along the axis AA, thereby allowing the magazine to move away from the head of the turret when the magazine is in a disengaged position.

[0022] In a particular embodiment, the magazine has a protective casing with a groove having an axial portion and a radial portion, which allows both the spindle and the tool to be stored to be inserted into the magazine and allows the magazine to be removed after the tool has been replaced.

[0023] In a particular embodiment, the shape of the radial portion of the groove corresponds to the shape of the spindle when the tool is replaced.

[0024] Other characteristics and advantages of the invention will become apparent on reading the detailed description given by way of example and without limitation with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 shows a perspective view of a multi-spindle turret according to a preferred exemplary embodiment of the present invention, comprising a tool gripping device capable of replacing tools carried by one or more spindles of the turret. [Diagram 2] 2 shows a view of the turret shown in FIG. 1 oriented in the direction of the main axis of the turret body. [Diagram 3] FIG. 2 shows a perspective view of the turret of FIG. 1 with a smaller tool-gripping device, illustrating its mobility over a particular angular range. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] For clarity, the figures are not necessarily drawn to scale.

[0027] The invention relates to a numerically controlled machine tool 10, preferably for machining micromechanical workpieces, comprising a multi-spindle turret 20 and a tool gripping device 30, as shown in FIG.

[0028] The turret 20 has a body 21 extending along a main axis referred to as the "AA axis," one end of which has a base 22 for fixing to the frame 11 of the machine tool 10, and at the other end of the body 21 has a head 23 which, in the exemplary embodiment of the invention shown in the drawings, can rotate about an axis which coincides with the axis AA.

[0029] The head 23 has at least two tool-holding spindles 24, 24' or 24", each spindle 24, 24' or 24" 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 work position intended to perform a machining operation on a workpiece held in a given position in the fixture, or a standby position disengaged from the workpiece. In Figures 1 to 4, the turret 20 has three spindles 24, 24' and 24", one of which is in the work position and two of which are in standby positions. It can now be seen that as the head 23 rotates the tools are changed, so that the tool 25 occupying the work position is moved to the standby position and one of the tools 25' or 25" that was in the standby position moves into the work position.

[0030] It should be noted that the turret 20 can be moved translationally, for example, by fixing the base 22 to a carriage (not shown) of the machine tool 10 that can move with at least one translational degree of freedom, and preferably three translational degrees of freedom, relative to the XYZ trihedron.

[0031] Alternatively, the turret 20 may be immobile, for example if the base 22 is fixed directly to the frame 11 of the machine tool 10. Optionally, a fixture is therefore provided with said degrees of freedom, for example three translational degrees of freedom in directions X, Y and Z, or one or two rotational degrees of freedom about directions X and / or Y.

[0032] The spindles 24, 24' and 24" are advantageously configured such that they can be controlled independently of one another to rotate or immobilize the tool 25, 25' or 25" that they carry. This feature is particularly advantageous when changing tools. Preferably, the spindles 24, 24' and 24" are motorized spindles, also known as "electric spindles", each having a dedicated motor for rotating or immobilizing the tool 25, 25' or 25" that they carry.

[0033] In particular, to replace a first tool 25 performing a first machining step with a second tool 25' or 25" intended to perform a second machining step, the latter second tool 25' or 25" is rotationally driven before the end of the first machining step until it reaches a rotational speed specific for the second machining step.

[0034] A first tool 25 is engaged with the spindle 24 in the work position and a second tool 25' or 25'' is engaged with one of the spindles 24' or 24'' in the standby position.

[0035] Once the first machining stage is completed, the head 23 rotates to move the spindle 24 that was in the work position to the standby position and the spindle 24' or 24" that was in the standby position to the work position. The second machining stage is then immediately started by the second tool 25' or 25" reaching its machining rotational speed while the engaged spindle 24' or 24" is in the standby position. Once the spindle 24 carrying the first tool 25 is in the standby position, its rotational movement is stopped.

[0036] 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 when the tools are changed is reduced to the duration of the rotation of the head 23 along the axis AA.

[0037] As shown in FIG. 1, each spindle 24, 24' and 24" extends along a main axis, designated "axis BB", "axis B'-B'" and "axis B"-B", respectively, which also constitutes an axis of rotation. In the work position, as shown in FIGS. 1 and 3, spindle 24 is preferably oriented so that its axis BB is parallel to the vertical axis.

[0038] Advantageously, the invention allows for the replacement and storage of a tool 25' or 25" while a machining operation is being performed, which tool is carried and stored by one of the spindles 24' or 24" in a standby position and does not rotate. In particular, as will be explained below, the machine tool 10 is equipped with a tool gripping device 30 which is capable of picking up the tool 25' or 25" stored on the spindle 24' or 24" and inserting a new tool, referred to as a "replacement tool" 25''', into the spindle 24' or 24".

[0039] As shown in FIGS. 1-3, the tool gripping device 30 is fixed to the body 21 of the turret 20 , for example where the base 22 is fixed to a carriage that is movable relative to the frame 11 .

[0040] As can be seen from figures 1 to 3, the tool gripping device 30 comprises a tool magazine 34 held in a cantilevered configuration by a support structure 31. The magazine 34 comprises a tool storage barrel 340 with a number of recesses 341 intended to receive a replacement tool 25''' or a replaced tool. In particular, the recesses 341 may each have a radially opening opening capable of engaging and receiving a replacement tool 25''' or a replacement tool.

[0041] In this example, the storage barrel 340 may be in the form of a disk with recesses 341 evenly distributed around its circumference.

[0042] Each recess 341 may have a gripping member formed by a clamp 342, shown diagrammatically in detail in Fig. 2. Each clamp 342 is elastically deformable so as to be able to engage with a tool to receive it and hold it in place in the recess 341 by friction. In particular, the tool may have 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 are within the capabilities of the person skilled in the art to design.

[0043] In the exemplary embodiment of the invention shown in Figures 1 to 3, 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 particular the interacting spindle 24', in the standby position, so that each formed recess 341 can face the spindle 24'. This degree of freedom is represented by the arrow 40 in Figure 3.

[0044] Also, the storage barrel 340 and the spindle 24' with which it interacts can move in translation relative to one another along an axis parallel to the axis B'-B' of the spindle 24'. This relative mobility is preferably ensured by a translational degree of freedom of the storage barrel 340 along the axis CC, as indicated by the arrow 41 in Fig. 3. Alternatively, this relative mobility can be ensured by a translational degree of freedom of the spindle 24' along the axis B'-B' in the standby position.

[0045] In particular, to replace the tool 25' engaged with the spindle 24' in the standby position with a replacement tool 25''' disposed within the storage barrel 340, the storage barrel 340 is rotated so that the empty recess 341 faces the tool 25' to be stored, and the storage barrel 340 is translated toward the spindle 24' to insert the tool 25' to be stored into the recess 341. Here, as the tool 25' to be stored is inserted into the recess 341, the clamp 342 in the recess 341 deforms until it engages the annular groove 250 of the tool 25' to be stored. The tool 25' can then be removed for storage by translating the storage barrel 340 away from the spindle 24'. To insert a replacement tool 25''' onto this spindle 24', the storage barrel 340 is rotated until the replacement tool 25''' is aligned with the spindle 24' and then translated towards the spindle 24', engaging the replacement tool 25''' with the spindle 24'. A translational movement perpendicular to the axis B'-B' allows the replacement tool 25''' to be removed from the recess 341 in which it is located and secures the replacement tool 25'''' to the spindle 24'.

[0046] Furthermore, when the opening of the recess 341 is configured to open tangentially or perpendicularly to the storage barrel 340, the tool 25' to be stored is engaged with the recess 341 and the replacement tool 25''' is removed from the recess 341 by rotating the storage barrel 340 around the axis CC in two opposite directions.

[0047] In a manner well known to those skilled in the art, during such operations, the spindle 24' is controlled to release the tool 25' to be stored when the storage barrel 340 moves in translation opposite to the spindle 24', and is configured to lock the replacement tool 25''' when the replacement tool 25'''' is inserted into the spindle 24'.

[0048] Advantageously, the magazine 34 may have one or more translational or rotational degrees of freedom, which allow it to move between an active position and a disengaged position. As mentioned above, in the active position, the magazine 34 is in the immediate vicinity of the spindle 24' or 24", in particular the spindle 24', which is in the standby position, and the magazine 34 is intended to interact with this spindle to extract the tool 25 carried by it to be stored, and to insert a replacement tool 25''' into the spindle 24'. In the disengaged position, the magazine 34 is further away from the axis AA, and thus from the head 23, than when it is in the active position. Such an arrangement prevents any risk of collision of the magazine 34 during machining operations or when rotating the head 23 to replace a tool.

[0049] To this end, the support structure 31 is configured to move the magazine 34 between its active and disengaged positions.

[0050] In particular, as shown in Figures 1-3, the support structure 31 may include a coupling member 32 fixed to the body 21 of the turret 20 and connected to the magazine 34 by an arm 33. The arm 33 is configured to move the magazine 34 between its active and disengaged positions. In particular, the arm 33 may be configured to translate the magazine 34 along an axis substantially perpendicular to the axis B'-B' of the spindle 24' in a standby position with which the magazine 34 interacts, as shown by arrow 42 in Figure 3.

[0051] In this exemplary embodiment, translational mobility of the magazine 34 along an axis substantially perpendicular to the axis B'-B' of the spindle 24' is provided by a distal portion 330 of the arm 33, which is slidably connected to a proximal portion 331 fixed to the connecting member 32 and fixed to the magazine 34.

[0052] Alternatively, in an exemplary embodiment not shown, the magazine 34 can rotate relative to the arm 33 about an axis of rotation parallel to the axis B'-B' of the spindle 24' with which it is intended to interact, in order to move between its active and disengaged positions, such that the distal part 330 is connected by a pivot to the proximal part 331. Here, it can be seen that the magazine is rotated to eccentrically drive the storage barrel 340 to move away from or towards the spindle 24' with which it is intended to interact.

[0053] Preferably, the connecting member 32 is formed by a fixing ring arranged around the body 21 and fixed so as to be rotatable about the axis AA, as indicated by the arrow 44 in FIG. 3. The shape of the fixing ring allows an advantageous distribution of the forces involved. Thanks to this mobility, the magazine 34 can be moved to interact sequentially with all the spindles 24' and 24" that occupy the standby position, thereby replacing the tools 25' and 25" of said spindles, without rotating the head 23 of the turret 20.

[0054] Advantageously, the magazine 34 is further capable of translational movement relative to the connecting member 32 along an axis parallel to the axis AA, by means of the arm 33, which moves the magazine 34 away from the head 23 when in the disengaged position. In particular, as shown diagrammatically by the arrow 43 in Figure 3, a proximal portion 331 of the arm 33 may be fixed to the connecting member 32 so as to be capable of translational movement along an axis parallel to the axis AA.

[0055] Alternatively, the connecting member 32 may be secured to the body 21 of the turret 20 so as to be slidable along the axis AA.

[0056] In an exemplary embodiment of the invention in which the turret does not move relative to the frame 11, the fixture has suitable translational and rotational mobility for executing a machining program.

[0057] Advantageously, as shown in figures 1 to 3, the magazine 34 has a protective casing 35, shown in these figures in the form of a rigid wall of axisymmetric shape. Due to the above-mentioned kinematic system, the protective casing 35 has a groove 350 through which the tool 25', 25" or 25"' can pass when the magazine 34 moves.

[0058] In particular, groove 350 has an axial portion and a radial portion, which allows both spindle 24' and the tool 25' to be stored therein to be inserted into magazine 34, and allows magazine 34 to be removed after tool 25' or 25" has been replaced. Advantageously, the shape of the radial portion of groove 350 corresponds to the shape of spindle 24' when tool 25' or 25" is replaced.

[0059] In general, the implementations and embodiments discussed above have been described as examples and other alternatives are possible. [Explanation of symbols]

[0060] 10 Machine tools 11 Frame 20 Turret 21 Body 23 Head 24, 24', 24" Tool Holding Spindles 25, 25', 25" Tools 30 Tool gripping device 31 Support structure 32 Consolidated Members 33 Arm 34 Magazine 35 Protective casing 330 Distal part 331 Proximal part 340 Storage Barrel 350 Groove

Claims

1. A numerically controlled machine tool (10) comprising a multi-spindle turret (20) having a body (21), The body (21) extends along an axis A-A between a first end fixed to a frame (11) of the machine tool (10) and a second end at which a rotatable head (23) is located; The head (23) has at least two tool-holding spindles (24, 24', 24"), said spindles (24, 24', 24") are each intended to receive in engagement a cutting tool (25, 25', 25"); said spindle (24, 24', 24") occupies, depending on the angular position of said head (23), a work position intended to perform a machining operation on a workpiece held in a given position in a fixture, and a standby position disengaged from said workpiece; each spindle (24, 24', 24") is adapted to be controlled independently of the other spindles in order to immobilize or to rotate the tool (25, 25', 25") it carries, regardless of the position it occupies; the machine tool (10) further comprises a tool gripping device (30) configured to interact with the spindle (24', 24") in a standby position to retrieve a tool (25', 25") carried by the spindle (24', 24") for storage and to insert a replacement tool (25''') into the spindle (24', 24"); the tool gripping device (30) comprises a tool magazine (34) held in a cantilevered position by a support structure (31) fixed to the body (21) of the turret (20); The magazine (34) comprises a storage barrel (340) having rotational freedom about an axis C-C. A machine tool (10).

2. said magazine (34) being arranged such that said axis CC is parallel to the main axis B'-B' or B"-B" of the interacting spindle (24', 24") in the standby position; The storage barrel (340) and the spindle (24', 24") are translatable relative to one another along the axis CC.

2. The machine tool (10) according to claim 1 .

3. the magazine (34) has at least one translational or rotational degree of freedom that allows it to move between an active position and a disengaged position; In the active position, the magazine (34) is in close proximity to a spindle (24', 24") with which it is configured to interact; In the disengaged position, the magazine (34) is further from the axis A-A than when it is in the active position.

3. A machine tool (10) according to claim 1 or 2.

4. The support structure (31) includes a connecting member (32) fixed to the body (21) of the turret (20) and connected to the magazine (34) by an arm (33); The arm (33) is configured to move the magazine (34) between an active position and a disengaged position.

4. Machine tool (10) according to claim 3.

5. The arm (33) has a distal portion (330) fixed to the magazine (34) which is slidably or pivotally connected to a proximal portion (331) fixed to the connecting member (32).

5. Machine tool (10) according to claim 4.

6. At least two spindles (24', 24") occupy a standby position; The connecting member (32) is rotatably fixed to the body (21) of the turret (20) about the axis A-A and moves the magazine (34) from one spindle (24', 24") to another spindle (24") in a standby position.

5. Machine tool (10) according to claim 4.

7. The magazine (34) further has translational movement relative to the coupling member (32) along an axis parallel to the axis A-A, thereby moving the magazine away from the head of the turret when the magazine is in a disengaged position.

5. Machine tool (10) according to claim 4.

8. The connecting member (32) is secured to the body (21) of the turret (20) so as to be slidable along the axis A-A, thereby allowing the magazine to move away from the head of the turret when the magazine is in a disengaged position.

5. Machine tool (10) according to claim 4.

9. The magazine (34) has a protective casing (35) with a groove (350) having an axial portion and a radial portion, which allows both the spindle (24', 24") and the tool (25', 25") to be stored to be inserted into the magazine (34) and allows the magazine (34) to be removed after replacing the tool (25', 25").

2. The machine tool (10) according to claim 1 .

10. The shape of the radial portion of the groove (350) corresponds to the shape of the spindle (24', 24") when the tool (25', 25") is replaced. Machine tool (10) according to claim 9.

Images