Center drive machine and method for operating a center drive machine

Abstract

The present invention relates to a center-drive machine (1) for machining a rotationally driven workpiece (5), comprising a machining area (40) and a preparation area (50) arranged adjacent to the machining area (40), and at least two headstocks (10), wherein the respective headstock (10) has a spindle (11) with a receptacle (12) for force-clamping the workpiece (5) and can be set in rotation about a machine axis (X) via a spindle drive for machining the workpiece (5), and wherein a first of the at least two headstocks (10) and at least a second of the at least two headstocks (10) can be arranged alternately in the preparation area (50) for changing the workpiece and in the machining area (40) for simultaneously machining the ends (6, 7) of the workpiece (5) that are opposite one another in the machine axis (X) and for carrying out the workpiece change.

Description

[0001] The present invention relates to a center drive machine having the features of patent claim 1 and to a method for operating a center drive machine having the features of patent claim 12.

[0002] Center-drive machines are known in various designs from the prior art and are used for machining rotationally driven workpieces at both ends in a single setup. For example, a center-drive machine of this type is known from DE 103 49 437 B3. The center-drive machine has a headstock with a spindle that is rotationally driven in a spindle axis by a spindle drive in a machine axis. The spindle includes a holder into which the workpiece can be inserted and held by force. In addition, the center-drive machine includes at least one tool on each of two opposite sides of the headstock in the machine axis, which tool can be used to machine both opposite ends of the workpiece simultaneously.

[0003] Such center drive machines have proven themselves in the state of the art, since high accuracy of the workpiece can be achieved, particularly by machining both ends in a single clamping.

[0004] In order to machine a large number of workpieces in succession, the prior art, for example in DE 10 2011 013 457 A1, proposes workpiece changing devices for the automatic loading and unloading of workpieces. Such workpiece changing devices have proven successful in the automation of the manufacturing process, but it has proven disadvantageous that workpiece changing is time-consuming and slows down the production process. This is due in particular to the fact that clamping and unclamping the workpiece in the holder as well as inserting and removing the workpiece are time-consuming. Inserting the workpiece is particularly time-consuming because the workpieces are typically long shafts with comparatively small diameters. During loading, the workpiece is held at the end and transported to the spindle.The opposite end may continue to vibrate, which is why the process must be interrupted before inserting it into the holder so that the vibrations can subside.

[0005] Further prior art is EP 0 507 123 A2.

[0006] This is where the present invention comes in.

[0007] The present invention is dedicated to the task of proposing a suitably improved center-drive machine. The center-drive machine should enable short processing times and optimize automatic workpiece changeover.

[0008] These objects are achieved by a center drive machine having the features of patent claim 1 and by a method for operating a center drive machine for simultaneous machining in a machine axis opposite ends of a workpiece having the features of patent claim 12.

[0009] The center drive machine according to the invention for machining a rotationally driven workpiece comprises a machining area and a preparation area arranged adjacent to the machining area.

[0010] Furthermore, the center-drive machine comprises at least two headstocks, each headstock having a spindle with a holder for the workpiece to be machined. In particular, the holder is configured to hold the workpiece to be machined in a force-clamped manner. Furthermore, it is provided that the spindle can be set into rotation about a machine axis via a spindle drive for machining the workpiece.

[0011] The spindle is preferably hollow, allowing the workpiece to be inserted through the spindle. The spindle may also include a clamping device for clamping, in particular force-clamping, the workpiece.

[0012] Furthermore, the invention provides that a first of the at least two headstocks and at least a second of the at least two headstocks of the center drive machine can be arranged alternately in the preparation area and in the machining area by mutual interchange in order to machine the ends of the workpiece opposite in the machine axis in the machining area and simultaneously to carry out the workpiece change in the preparation area.

[0013] The present invention is based on the idea of ​​parallel loading during main machining. The workpiece change on the center-drive machine can be carried out at the same time as the machining of both ends of a workpiece in a single clamping operation, thereby achieving a considerable time advantage. While one workpiece is arranged for machining in the machining area by a first of the at least two headstocks, another workpiece can be removed from the at least one second of the at least two headstocks in the preparation area and replaced by another workpiece. In contrast to the prior art, the method steps of workpiece change and machining can therefore be carried out in parallel and not one after the other as was previously the case in the prior art.

[0014] Furthermore, it has proven advantageous if the machining area and the preparation area are arranged adjacently transversely to the machine axis. The machining area and the preparation area can be arranged adjacently transversely to the machine axis, which is preferably approximately parallel to a longitudinal axis of the center-drive machine. In particular, it is preferred if the machining area and the preparation area are arranged adjacently, preferably directly adjacent to one another, transversely to the machine axis. This arrangement allows the distance between the machining area and the preparation area to be as small as possible, whereby the headstocks in the preparation area and the machining area can be exchanged particularly quickly.

[0015] The center drive machine can have a horizontal or vertical arrangement of the machine longitudinal axis and / or the machine axis and / or the longitudinal axis of the workpiece.

[0016] A further development of the present invention provides that the machining area and the staging area are spatially separated. The spatial separation of the machining area and the staging area is intended to prevent process materials such as chips, oils, coolants, etc. from passing from the machining area into the staging area and potentially contaminating the headstock located there. It is particularly preferred if a wall is provided between the machining area and the staging area. The wall can also have a door, for example in the form of a sliding or revolving door, through which the headstocks can pass from the machining area to the staging area and vice versa.To change the at least two headstocks, the door can, for example, perform a rotary movement or a linear movement to enable the at least two headstocks to be changed between the two areas.

[0017] A further development of the present invention provides that at least one tool for machining the rotating workpiece is arranged on opposite sides of the machining area in the machine axis of the headstock located there. The at least one tool preferably serves for machining the workpiece rotating in the machine axis, whereby the following processes can be implemented - not exclusively: turning, milling, drilling, grinding, honing, and slotting.

[0018] The at least one tool can be interchangeable. For example, at least one tool turret can be provided with the at least one tool, wherein the tool turret can typically comprise a plurality of different tools that can be brought into engagement with the workpiece by the tool turret.

[0019] A further development of the present invention provides for a workpiece changing device to be arranged in the preparation area. The workpiece changing device is particularly configured to load and / or unload a workpiece from the headstock arranged in the preparation area. The workpiece changing device enables automated workpiece changing, thereby achieving a very high degree of automation.

[0020] According to a further development of the present invention, it is advantageous if the at least two headstocks can be moved back and forth between the machining area and the preparation area by a movement device. For example, the exchange of the at least two headstocks between the machining area and the preparation area can be achieved by a rotary and / or linear movement. The movement device can further comprise locking means by which at least the headstock arranged in the machining area is held in a preferably precisely positioned position in the machining area.

[0021] For example, according to a preferred development of the present invention, the movement device can comprise a platform on which the at least two headstocks can be arranged. In a preferred embodiment, the platform can, for example, comprise a turntable on which the at least two headstocks are fixedly arranged. By rotating the turntable in an axis transverse to the machine axis, the headstocks arranged on diametrically opposite sides can be exchanged between the processing area and the preparation area. The aforementioned door of the wall can, for example, be arranged on the turntable between the two headstocks.

[0022] The spindle comprises a clamping device designed to force-clamp the workpiece, which clamping device is preferably hydraulically actuated. Furthermore, it is preferred if the clamping force of the clamping device is adjustable by hydraulic pressure. Unlike spring-loaded clamping devices, the clamping force can be adjusted to suit the specific application by applying appropriate pressure.

[0023] The spindle can, for example, be connected to a hydraulic circuit of the center-drive machine. The connection to the hydraulic circuit can be disconnected for machining the workpiece. The hydraulic pressure, and thus the clamping force, can be maintained by appropriate valves, particularly in the spindle.

[0024] A further development of the present invention provides that a docking unit can establish a hydraulic connection between the headstock and the spindle. The docking unit can connect a hydraulic circuit of the center drive machine to the spindle. The docking unit can, for example, approach the spindle when stationary and dock lines of the hydraulic circuit of the center drive machine to the spindle to connect the spindle to the hydraulic circuit. The docking unit preferably comprises a supply line and a discharge line for the hydraulic circuit. Furthermore, the docking unit can transmit additional media to the spindle, such as compressed air or the like.

[0025] Furthermore, it has proven advantageous if the at least two headstocks each have a spindle drive or a common spindle drive. In particular, it is advantageous if the spindle drive is driven by the respective spindle via a belt.

[0026] A further aspect of the present invention relates to a method for operating a center-drive machine, in particular a center-drive machine as described above, for simultaneous machining in a machine axis at opposite ends of a workpiece that is rotationally driven in the machine axis. The center-drive machine comprises a machining area, a preparation area arranged adjacent to the machining area, and at least two headstocks. Each headstock further comprises a drivable spindle with a holder for power clamping a workpiece. The method for operating the drive machine comprises the following method steps: - Carrying out a workpiece change in the preparation area on one of at least two headstocks, - Machining a workpiece clamped and rotationally driven by the other of the at least two headstocks in the machining area and - preferential mutual exchange of at least two headstocks in the preparation area and the machining area.

[0027] Furthermore, it has proven advantageous in the implementation of the method that the workpiece change on one of the at least two headstocks can take place simultaneously with the machining of the workpiece clamped in the other of the at least two headstocks. By simultaneously changing the workpiece in the staging area and machining another workpiece in the machining area, a significant time advantage can be achieved.

[0028] Furthermore, it has proven advantageous if the tool change is performed using a workpiece changing device. The workpiece changing device can load and / or unload a workpiece onto the headstock located in the staging area and can enable automated workpiece changing.

[0029] Furthermore, it has proven advantageous if, when changing the workpiece, the workpiece is arranged in the holder of the respective headstock in such a way that the two ends of the workpiece are arranged on opposite sides of the spindle in the machine axis.

[0030] Furthermore, it is also advantageous if the workpiece is clamped by force in the preparation area. On the one hand, this protects the workpiece from accidental displacement within the spindle mount during movement from the preparation area to the machining area, and on the other hand, this can result in a simplified design of the center-drive machine.

[0031] Furthermore, it has proven to be advantageous if the preferably mutual exchange of the at least two headstocks in the preparation area and the processing area takes place at the same time, i.e. simultaneously, in particular in a synchronous, even more preferably in a common movement.

[0032] A highly simplified embodiment is described in detail below with reference to the accompanying figures. They show: Fig. 1 a perspective view of a center drive machine with a machining area arranged between two tools and a preparation area arranged next to the machining area and two headstocks, Fig. 2 a plan view of the center drive machine according to Fig. 1, Fig. 3 a side view of the center drive machine according to Fig. 1 and, Fig. 4 a highly simplified sectional view of the center drive machine according to the section line AA in Fig. 2.

[0033] Identical or functionally equivalent parts or features are identified by the same reference numerals in the following detailed description of the figures. Likewise, not all identical or functionally equivalent parts or features are provided with a reference numeral in the figures.

[0034] The Fig. 1 to 4 show a highly simplified center drive machine 1 for machining a rotatably driven workpiece 5.

[0035] The workpiece 5 can, for example, be a shaft and has a longitudinal axis L which approximately corresponds to an axis of symmetry of the workpiece 5 and extends over a first end 6 and a second end 7.

[0036] The center drive machine 1 comprises a machining area 40 and a preparation area 50. Furthermore, according to the illustrated embodiment, the center drive machine 1 comprises two headstocks 10 and at least two tools 21, 22.

[0037] The center drive machine 1 can have a machine longitudinal axis, wherein in the machining area 40 the headstock 10 is arranged in the machine longitudinal axis between the two tools 21, 22.

[0038] For better understanding, in the following description, one headstock 10 is shown without any separate marking in the figures and the other headstock 10' and its components are marked with an additional "'". It is noted at this point that the two headstocks 10, 10' are preferably of identical construction.

[0039] The respective headstock 10 comprises a spindle 11 and a spindle drive 16.

[0040] Furthermore, the headstock 10 has a housing 14, referred to as a whole, wherein the housing 14 can consist of two assembled housing parts. The housing 14 can house the spindle and / or the spindle drive 16.

[0041] The spindle 11 is mounted on the headstock 10 so as to be rotatable along a machine axis X and can be driven by the spindle drive 16. The machine axis X is preferably arranged parallel to the machine's longitudinal axis. The first tool 21 and the second tool 22 are each arranged in the machining area 40 of the center-drive machine 1, with the respective rotationally driven workpiece 5 being machined in the machining area 40.

[0042] The center drive machine 1 can have a horizontal or vertical arrangement of the machine longitudinal axis and / or the machine axis X and / or the longitudinal axis L of the workpiece 5.

[0043] The spindle drive 16 drives - as in particular the Fig. 4 can be removed - the spindle 11, for example by means of a toothed belt 17.

[0044] The spindle 11 is also hollow and comprises a receptacle 12 and clamping means not shown.

[0045] A workpiece 5 can be inserted through the holder 12 - as shown in particular in the Fig. 2 and Fig. 3 - are inserted into the spindle 10 in such a way that the two ends 6 and 7 are arranged on opposite sides of the headstock 10.

[0046] The clamping device is configured for force-clamping the workpiece 5 and is preferably hydraulically actuated, allowing the clamping device to be opened and / or closed hydraulically. It is particularly preferred if the clamping force of the clamping device is also generated hydraulically, allowing the clamping force to be adjusted by pressure. For example, it is possible to hold a workpiece 5 clamped with different pressures in the holding force.

[0047] To operate the clamping device, the headstock 10 can be moved as shown in Fig. 4, comprise a docking unit 15, wherein the docking unit 15 can establish a hydraulic connection between the headstock 10 and the spindle 11. The docking unit 15 can connect a hydraulic circuit of the center drive machine 1 to the spindle 11. The docking unit 15 can, in particular, move up to the spindle 11 when stationary and dock lines of the hydraulic circuit of the center drive machine 1 to the spindle 11 to connect the spindle 11 to the hydraulic circuit. The docking unit 15 preferably comprises a supply line and a discharge line for the hydraulic circuit, wherein the supply line and the discharge line can each be provided through a docking nozzle 18.

[0048] In addition, the docking unit 15 can transmit additional media to the spindle 11. In the illustrated embodiment, the docking unit 15 comprises three docking ports 18, wherein the third docking port 18 can transmit, for example, compressed air or another medium.

[0049] To actuate the clamping device, the spindle 11 is first rotated to the correct angular position by the spindle drive 16. The docking unit 15 can then be docked to the spindle 11 via a linear guide and connected to the hydraulic circuit of the center drive machine 1.

[0050] The center drive machine 1 further comprises at least a first tool 21 and a second tool 22. The first tool 21 and / or the second tool 22 can be arranged, for example, on a tool turret 23, 24, wherein the tool turret 23, 24 can have a plurality of tools 21, 22, which make it possible, for example, to carry out the processes of turning, milling, drilling, grinding, honing and slotting.

[0051] In the machining area 40, the two spindle stocks 10, 10' can be arranged alternately, in particular in the machine axis X between the first tool 21 and the second tool 22.

[0052] According to the preferred embodiment shown, the processing area 40 can be arranged spatially separate from the preparation area 50. The processing area 40 and the preparation area 50 are arranged adjacent, preferably directly adjacent, transversely to the machine axis X or the machine longitudinal axis.

[0053] The spatial separation of the machining area 40 and the preparation area 50 is intended to prevent process materials such as chips, oils, coolants, etc. from passing from the machining area 40 into the preparation area 50 and possibly contaminating the headstock 10' there.

[0054] For this purpose, a wall 45 may be provided, wherein the wall preferably comprises a door 46 which can be opened for the exchange of the headstocks 10, 10'.

[0055] For example, the door 46 can be designed as a sliding or revolving door. The door 46 can be opened to change the at least two headstocks 10, 10'. For example, the door 46 can perform a rotary or linear movement and expose an opening through which the headstocks 10, 10' can be passed when changing the headstocks 10, 10'.

[0056] The arrangement of the two headstocks 10, 10' in the preparation area 50 and the machining area 40 can be exchanged, whereby a workpiece change can be carried out simultaneously on one of the two headstocks 10' and both ends 6, 7 can be machined simultaneously in a single clamping on the other of the two headstocks 10.

[0057] The change of the headstocks 10, 10' from the machining area 40 to the preparation area 50 is preferably carried out by a movement device 30, by means of which the at least two headstocks 10, 10' can be moved between the machining area 40 and the preparation area 50.

[0058] In the illustrated embodiment, the movement device 30 comprises a platform 31 which is rotatable about an axis of rotation R and is designed as a turntable, on which the headstocks 10, 10' can be arranged.

[0059] According to the illustrated embodiment, the platform 31 may have inclined surfaces that promote the drainage of substances such as chips, coolant and the like.

[0060] The platform 31 can mutually exchange the spindle heads 10, 10' between the machining area 40 and the preparation area 50 by rotating about the rotation axis R, wherein preferably the rotational movement in Fig. 2 is indicated by a double arrow. To remain with this exemplary embodiment, the door 46 can be arranged between the two headstocks 10, 10' on the platform 31. In this exemplary embodiment, the door 46 rotates like a revolving door together with the headstocks 10, 10' in the rotation axis R.

[0061] However, it is noted at this point that the movement device 30 can carry out the exchange of the two headstocks 10, 10' in the machining area 40 and in the preparation area 50 by any movement, wherein typically the movement can be a rotary and / or a linear movement.

[0062] The movement device 30 can further comprise locking means by which at least the headstock 10, 10', which is arranged in the machining area 40, can be held in a preferably precisely positioned manner in the machining area 40.

[0063] The center drive machine 1 described above can carry out a method for simultaneous machining in a machine axis at opposite ends 6, 7 of a workpiece 5 that is rotationally driven in the machine axis X. The method comprises in particular the method steps - Carrying out a workpiece change in the preparation area 50 on one of the at least two headstocks 10, 10', - Machining a workpiece 5 held by the other of the two headstocks 10, 10', preferably by force clamping, in the machining area 40 and - preferential mutual exchange of the two headstocks 10, 10' between the preparation area 50 and the machining area 40.

[0064] In order to make the process particularly efficient, the workpiece change on the headstock 10' in the preparation area 50 is carried out simultaneously with the machining of a workpiece 5 driven by the headstock 10 in the machining area 40. By simultaneously changing a workpiece 5 in the preparation area 40 and machining another workpiece 5 in the machining area 40, a considerable time advantage can be achieved. List of reference symbols 1 center drive machine 5 Workpiece 6 End 7 End 10 Headstock 11 spindle 12 recordings 14 housings 15 Docking unit 16 spindle drive 17 Timing belt 18 docking ports 21 Tools 22 tools 23 tool turrets 24 tool turrets 30 Movement device 31 Platform 40 Editing area 45 wall 46 Door 50 staging area L Longitudinal axis of 5 X machine axis of 10

Claims

[1] Center drive machine (1) for machining a rotationally driven workpiece (5), comprising - a processing area (40) and a preparation area (50) arranged adjacent to the processing area (40), and - at least two headstocks (10), - wherein the respective headstock (10) has a spindle (11) with a receptacle (12) for clamping the workpiece (5) and can be set in rotation about a machine axis (X) via a spindle drive (16) for machining the workpiece (5), and - wherein a first of the at least two headstocks (10) and at least a second of the at least two headstocks (10) can be arranged by mutual interchange alternately in the preparation area (50) for changing the workpiece and in the machining area (40) for simultaneously machining the ends (6, 7) of the workpiece (5) opposite one another in the machine axis (X) and for carrying out the workpiece change. [2] Center drive machine (1) according to one of the preceding claims, characterized by that the processing area (40) and the preparation area (50) are arranged adjacent to each other transversely to the machine axis (X). [3] Center drive machine (1) according to one of the preceding claims, characterized by that the processing area (40) and the preparation area (50) are spatially separated. [4] Center drive machine (1) according to one of the preceding claims, characterized bythat in the machine axis (X) on opposite sides of the machining area (40) at least one tool (21, 22) for machining the ends (6, 7) of the workpiece (5) is arranged. [5] Center drive machine (1) according to one of the preceding claims, characterized by that a workpiece changing device is arranged in the preparation area (50). [6] Center drive machine (1) according to one of the preceding claims, characterized by that the at least two headstocks (10) can be moved by a movement device (30) between the processing area (40) and the preparation area (50). [7] Center drive machine (1) according to one of the preceding claims, characterized by that the movement device (30) comprises a platform (31) on which the at least two headstocks (10) can be arranged. [8] Center drive machine (1) according to one of the preceding claims, characterized bythat the spindle (11) of the respective headstock (10) can apply a clamping force hydraulically. [9] Center drive machine (1) according to one of the preceding claims, characterized by that a docking unit (15) can establish a hydraulic connection between the headstock (10) and the spindle. [10] Center drive machine (1) according to one of the preceding claims, characterized by that the at least two headstocks (10) each have a spindle drive (16) or each have their own spindle drive (16). [11] Center drive machine (1) according to one of the preceding claims, characterized by that the spindle (11) of the respective headstock (10) can be driven by the spindle drive (16) by means of a toothed belt (17). [12] Method for operating a center drive machine (1), in particular a center drive machine (1) according to one of the preceding claims, for simultaneous machining in a machine axis (X) at opposite ends (6, 7) of a workpiece (5) that is rotationally driven in the machine axis (X), wherein the center drive machine (1) has a machining area (40), a preparation area (50) arranged adjacent to the machining area (40) and at least two headstocks (10), wherein the respective headstock (10) has a drivable spindle (11) with a holder (12) for power clamping the workpiece (5), comprising the following method steps: - carrying out a workpiece change in the preparation area (50) on one of the at least two headstocks (10), - machining a workpiece (5) held clamped and rotationally driven by the other of the at least two headstocks (10) in the machining area (40), and - Replacing at least two headstocks (10) in the preparation area (50) and in the machining area (40). [13] Method according to claim 12, characterized by that the workpiece change on one of the at least two headstocks (10) takes place simultaneously with the machining of a workpiece (5) which is held clamped in the other of the at least two headstocks (10). [14] Method according to claim 12 or 13, characterized by that the workpiece change is carried out by a tool changing device. [15] Method according to one of claims 12 to 14, characterized bythat when changing the workpiece, the workpiece is arranged in the holder of the respective headstock (10) in such a way that the two ends (6, 7) of the workpiece (5) are arranged in the machine axis (X) on opposite sides of the headstock (10). [16] Method according to one of claims 12 to 15, characterized by that the force clamping of the workpiece (5) takes place in the preparation area (50). [17] Method according to one of claims 12 to 16, characterized by that the exchange of the at least two headstocks (10) in the preparation area (50) and in the processing area (40) takes place simultaneously, in particular in a synchronous movement.

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