Index device for machine tool and control method thereof

Abstract

The present invention precisely rotates an index table to a predetermined angle. This index device 1 comprises: a housing 11 that is installed on a main table 20 of a machine tool 2; an index table 10 that is rotatably supported by the housing 11 and indexes a workpiece W; a power transmission mechanism 3 that causes extra relative movements of a spindle 21 and a main table 20 of the machine tool 2 to be generated separately from the machining relative movements of the spindle 21 and the main table 20, and transmits the extra relative movements to the rotation of the index table 10; and an angle detection unit 4 that detects the angle of the index table 10. A control unit 25 of the machine tool 2 is configured to use the detection angle of the angle detection unit 4 to control the extra relative movements of the machine tool 2 and rotate the index table 10 to a predetermined angle.

Description

[Technical Field]

[0001] The present invention relates to an indexing device for a machine tool that machines a workpiece, and a control method thereof. [Background technology]

[0002] An indexing device for a machine tool includes an index table that indexes a workpiece, and a power transmission mechanism that transmits the extra relative movement between the spindle and main table of the machine tool, separate from the relative machining movement between the spindle and main table, to the rotational movement of the index table (see, for example, Patent Document 1).

[0003] This indexing device is installed in a machine tool and rotates the index table by using the extra relative movement between the spindle and the main table. Because this indexing device rotates the index table using the extra relative movement between the spindle and the main table of the machine tool, there is no need to provide an electric, hydraulic, or pneumatic drive device, making the configuration simple and low-cost. Furthermore, there is no need to install special electrical wiring, hydraulic piping, or pneumatic piping for the drive device, so there is no problem with space.

[0004] On the other hand, in the case of this indexing device, the amount of rotation of the index table relative to the amount of extra relative movement of the machine tool may differ for each machine tool depending on the structural characteristics and installation location of the machine tool on which the indexing device is installed, etc. Therefore, even if the amount of extra relative movement of the machine tool is preset, it may not be possible to accurately rotate the index table to the specified angle.

[0005] Therefore, before indexing a workpiece on the index table, the operator had to manually operate each machine tool and record the amount of rotation of the index table corresponding to the amount of extra relative movement of the machine tool, which required prior work.As a result, when there were a large number of machine tools, the operator had to manually perform a large amount of work in advance, which resulted in the problem of increased work time and labor. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-259969 Summary of the Invention [Problem to be solved by the invention]

[0007] SUMMARY OF THE INVENTION An object of the present invention is to provide an index device for a machine tool that can accurately and easily rotate an index table to a predetermined angle, and a control method therefor. [Means for solving the problem]

[0008] In order to solve the above problems, an index device for a machine tool according to the present invention comprises: An indexing device for a machine tool that machines a workpiece, The indexing device a housing installed on a main table of the machine tool; an index table that is rotatably supported by the housing and indexes the workpiece; a power transmission mechanism that transmits an extra relative movement between the spindle and the main table to the rotation of the index table, in addition to the relative movement between the spindle and the main table of the machine tool during machining; an angle detection unit that detects the angle of the index table, The control unit of the machine tool is configured to use the angle detected by the angle detection unit to control the extra relative movement of the machine tool and rotate the index table by a predetermined angle.

[0009] This allows the index device to rotate the index table accurately to a predetermined angle for each machine tool, even when the index device is installed on a machine tool and the index table is rotated by extra relative movement of the machine tool.

[0010] Preferably, the control unit uses the detected angle to feedback control the extra relative movement of the machine tool, thereby rotating the index table to a predetermined angle.

[0011] In this way, the indexing device is feedback controlled using the detected angle, so that the index table can be rotated accurately to a predetermined angle even if a disturbance occurs in the motion transmission mechanism.

[0012] Preferably, the control unit includes a memory unit that uses the detected angle to store the coordinates of the extra relative movement of the machine tool relative to a predetermined angle of the index table, and controls the extra relative movement of the machine tool using a program that uses the coordinates relative to the predetermined angle as variables to rotate the index table to the predetermined angle.

[0013] In this way, the indexing device stores the coordinates of the extra relative movement of the machine tool relative to multiple predetermined angles of the index table, and by using a program that uses the coordinates of the extra relative movement of the machine tool relative to the predetermined angles of the index table as variables, it is possible to quickly and accurately rotate the index table to a predetermined angle.

[0014] Preferably, the control unit receives a skip signal when the detected angle reaches a predetermined angle.

[0015] This makes it possible to control the extra relative movement of the machine tool in the case of a machine tool controlled by a program that operates based on a skip signal by inputting a skip signal to the control unit of the machine tool based on the detected angle from the angle detection unit of the index table.

[0016] Preferably, The power transmission mechanism is a push bar movably supported on the housing; The housing includes a push bar interlocking mechanism that is provided between the push bar and the index table and that interlocks with the push bar to rotate the index table.

[0017] This allows the index table to be rotated to a predetermined angle by moving the push bar of the index device with an extra relative movement of the machine tool.

[0018] Further, a control method for an index device of a machine tool according to the present invention includes: A method for controlling an index device of a machine tool that machines a workpiece, comprising: The indexing device a housing installed on a main table of the machine tool; an index table that is rotatably supported by the housing and indexes the workpiece; a power transmission mechanism for transmitting an extra relative movement between the spindle and the main table to the rotation of the index table, in addition to the relative movement between the spindle and the main table of the machine tool for machining; The control method is detecting the angle of the index table; using the detected angle to generate extra relative movement of the machine tool; and transmitting the extra relative movement of the machine tool to the rotation of the index table to rotate the index table to a predetermined angle.

[0019] This allows the index device to rotate the index table accurately to a predetermined angle for each machine tool, even when the index device is installed on a machine tool and excess relative movement of the machine tool is transmitted to the rotation of the index table. [Effects of the Invention]

[0020] The index device for a machine tool and the control method thereof according to the present invention can accurately rotate the index table to a predetermined angle. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 2 is a side view showing the index device and the machine tool. [Figure 2] FIG. 2 is a front view showing the index device and the machine tool. [Figure 3] FIG. [Figure 4] FIG. 4 is an explanatory diagram showing a push bar interlocking mechanism. [Figure 5] FIG. 4 is a flowchart showing the control of the index device and the machine tool in the first embodiment. [Figure 6] FIG. 4 is a flowchart showing control of a transmitter and a receiver in the first embodiment. [Figure 7] FIG. 10 is a flowchart showing the control of the index device and the machine tool in the second embodiment. [Figure 8] FIG. 10 is a flowchart showing control of a transmitter and a receiver in the second embodiment. [Figure 9] A diagram showing a variable list. DETAILED DESCRIPTION OF THE INVENTION

[0022] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An indexing device for a machine tool and a control method thereof according to an embodiment of the present invention will now be described with reference to the accompanying drawings. The X-axis, Y-axis, and Z-axis are arranged at right angles to one another.

[0023] <Configuration of index device 1 and machine tool 2> The configurations of the index device 1 and the machine tool 2 will be described with reference to FIGS.

[0024] 1 and 2, the indexing device 1 is configured separately from the machine tool 2 and is configured to be installed on the main table 20 of the machine tool 2 for use. The indexing device 1 is configured to grip and index a workpiece W. The machine tool 2 is configured to move a tool 210 attached to a spindle 21, thereby machining the workpiece W indexed by the indexing device 1.

[0025] The index device 1 includes a housing 11 and an index table 10, and the index table 10 is rotatably supported by the housing 11, and is configured so that a workpiece W is held on the index table 10. The index table 10 is configured so as to be rotatable around a rotation axis 10a.

[0026] The indexing device 1 has a push bar 30 movably supported on a housing 11. The machine tool 2 is equipped with a control unit 25. The control unit 25 is a computer made up of a calculation unit such as a CPU, an auxiliary storage unit such as an HDD or SSD that stores various computer programs, a main storage unit such as a RAM that stores data for the calculation unit to execute the computer programs, an input unit such as a keyboard for input by an operator, and an output unit such as a display that displays information to the operator.

[0027] The control unit 25 controls the spindle 21 to move relative to the main table 20 and to rotate the spindle 21 at high speed, thereby machining the workpiece W indexed by the index device 1 installed on the main table 20.

[0028] Furthermore, the control unit 25 generates an extra relative movement between the spindle 21 and the main table 20 in addition to the relative movement between the spindle 21 and the main table 20 for machining, and moves the push bar 30 by this extra relative movement.

[0029] The indexing device 1 is equipped with a power transmission mechanism 3 that transmits the excess relative movement between the spindle 21 and main table 20 of the machine tool 2 to the rotation of the indexing table 10. The power transmission mechanism 3 is provided inside the housing 11, and includes a locking mechanism 31 (Fig. 3) and a push bar interlocking mechanism 32 (Fig. 4).

[0030] 3, the index table 10 is locked by the locking mechanism 31, and when the push bar 30 is moved, the index table 10 is unlocked thereby. The locking mechanism 31 has a rod member 310, and one end of the rod member 310 is formed with a toothed portion 311, which is configured to mesh with a gear (not shown) fixed to the index table 10. The index table 10 is locked by meshing the toothed portion 311 with the gear of the index table 10.

[0031] Furthermore, a cam groove 313 is formed in the push bar 30, and a pin 312 is provided on the rod member 310 and inserted into the cam groove 313. The cam groove 313 extends in the axial direction of the push bar 30 and is inclined obliquely. When the push bar 30 moves, the rod member 310 is moved accordingly by the cam groove 313 and the pin 312, and the tooth portion 311 of the rod member 310 is pulled out of the gear of the index table 10, thereby unlocking the index table 10.

[0032] As shown in Figure 4, push bar linkage mechanism 32 is provided within housing 11 between push bar 30 and index table 10, and is linked to push bar 30 to rotate index table 10. Push bar linkage mechanism 32 has a feed pawl 321, which is attached to push bar 30. Push bar linkage mechanism 32 also has a ratchet wheel 322, which is attached to index table 10. As push bar 30 moves, feed pawl 321 engages with the teeth of ratchet wheel 322, and feed pawl 321 causes ratchet wheel 322 and index table 10 to rotate.

[0033] Furthermore, as will be described later, after the index table 10 is unlocked, the index table 10 is rotated by the push bar interlocking mechanism 32.

[0034] Then, the control unit 25 causes additional relative movement between the spindle 21 and the main table 20, and first the spindle 21 and the tool 210 move in the X and Y directions to position the spindle 21 above the push bar 30. After that, the spindle 21 and the tool 210 move in the Z direction toward the push bar 30, the tool 210 pushes the push bar 30, and the locking mechanism 31 unlocks the index table 10.

[0035] Further, the push bar 30 is then pushed by the spindle 21 and the tool 210, and the index table 10 is rotated by the push bar interlocking mechanism 32. Therefore, the workpiece W rotates integrally with the index table 10. Thereafter, the spindle 21 and the tool 210 move away from the push bar 30, and the push bar 30 returns to its original position by the spring 320.

[0036] Furthermore, the push bar 30 is then pushed by the spindle 21 and the tool 210, the push bar 30 returns to its original position by the spring 320, the push bar 30 pushes away again, and the index table 10 rotates again. This is repeated several times, and the index table 10 rotates by a predetermined angle. This causes the workpiece W to be indexed.

[0037] Thereafter, the spindle 21 and the tool 210 move in the Z direction away from the push bar 30. Therefore, the index table 10 is locked by the locking mechanism 31. Thereafter, the control unit 25 causes relative movement for machining between the spindle 21 and the main table 20, and the tool 210 is pressed against the workpiece W, and the workpiece W is machined by the tool 210.

[0038] In this way, the indexing device 1 is configured so that the indexing table 10 rotates by the extra relative movement between the spindle 21 of the machine tool 2 and the main table 20, and by the power transmission mechanism 3, and therefore the indexing device 1 does not have a drive device such as a rotary motor for rotating the indexing table 10.

[0039] As shown in Fig. 1, the indexing device 1 further includes an angle detection unit 4 that detects the angle of the indexing table 10. The angle detection unit 4 is configured as an encoder connected to the rotation shaft 10a of the indexing table 10. The indexing device 1 includes a transmitter 40 connected to the angle detection unit 4, and is configured so that a signal of the angle detected by the angle detection unit 4 is transmitted by the transmitter 40 wirelessly or via a wire.

[0040] Machine tool 2 also includes receiver 23, which is configured to receive the signal from transmitter 40 wirelessly or via a wire. Receiver 23 is connected to control unit 25, which is configured to sequentially send the detected angle signal from angle detection unit 4 to control unit 25. Control unit 25 uses the detected angle signal from angle detection unit 4 to control the additional relative movement of machine tool 2 and rotate index table 10 to a predetermined angle.

[0041] First Embodiment The control of the index device and machine tool in the first embodiment will be described with reference to FIGS.

[0042] 5, the operator inputs and sets the target angle of index table 10 into control unit 25, and the target angle is stored in memory unit 250 (FIG. 1) of control unit 25 (step S10). Then, control unit 25 moves spindle 21 in the X and Y directions to position it above push bar 30 (step S11). Control unit 25 transmits to receiver 23 an operation start signal that starts the operation of the extra relative movement of machine tool 2, and the set target angle (step S12).

[0043] When control unit 25 transmits an operation start signal and a target angle to receiver 23, receiver 23 and transmitter 40 start communication, and as shown in Fig. 6, transmitter 40 sequentially transmits the current angle of index table 10 detected by angle detection unit 4 to receiver 23 (step S30). Then, transmitter 40 sequentially transmits the current angle of index table 10 to receiver 23 until the angle detected by angle detection unit 4 from receiver 23 reaches within an allowable range for the target angle (step S31). The tolerance for the target angle refers to the range of error (a few mm degrees) that is permissible for the target angle.

[0044] 5, the control unit 25 moves the spindle 21 in the Z direction to push in the push bar 31 (step S13). As the push bar 31 is pushed in, the index table 10 rotates (step S14).

[0045] As shown in Fig. 6, when the angle detected by the angle detector 4 from the transmitter 40 falls within the allowable range for the target angle, the receiver 23 outputs a skip signal (step S32). As shown in Fig. 5, the control unit 25 determines whether this skip signal has been input (step S15). If the skip signal has not been input, the control unit 25 determines whether the push bar 30 has reached the limit coordinate position (step S16). The limit coordinate position refers to the coordinate of the spindle 21 up to the limit at which the push bar 30 is allowed to be pushed.

[0046] If the push bar 30 has not reached the limit coordinate position, the control unit 25 causes the spindle 21 to push the push bar 30 and rotate the index table 10 (steps S13, S14) until a skip signal is input (steps S15, S16).

[0047] Furthermore, when the push bar 30 reaches the limit coordinate position even though a skip signal has not been input (steps S15 and S16), the index table 10 cannot be rotated to the target angle, so the spindle 21 rises to lock the index table 10 (step S19), and the situation is treated as an indexing error (step S20).

[0048] As shown in FIG. 6, when the angle detected by the angle detection unit 4 from the transmitter 40 reaches within the allowable range for the target angle, the receiver 23 outputs a skip signal (step S32), and as shown in FIG. 5, the control unit 25, upon receiving the skip signal, raises the spindle 21 and locks the index table 10 (steps S15, S17).

[0049] Control unit 25 determines whether the angle detected by angle detection unit 4 from receiver 23 is within an allowable range for the target angle (step S18). If the detected angle is within the allowable range of the target angle, control unit 25 ends the operation of the extra relative movement of machine tool 2. On the other hand, if the detected angle is not within the allowable range of the target angle, control unit 25 returns to step S12, where it again transmits to receiver 23 an operation start signal for starting the operation of the extra relative movement of machine tool 2 and the set target angle (step S18).

[0050] As described above, in the first embodiment, the control unit 25 is configured to constantly use the detected angle of the angle detection unit 4 to feedback control any excess relative movement of the machine tool 2, thereby rotating the index table 10 to the target angle.

[0051] Second Embodiment Next, the control of the index device and machine tool in the second embodiment will be described with reference to FIGS.

[0052] In the second embodiment, a relative movement program for executing an extra relative movement of the machine tool 2 is stored in the storage unit 250 of the control unit 25. In the relative movement program, custom macro variables are assigned to a plurality of index angles at predetermined angle intervals in the index table 10. Therefore, as shown in FIG. 9, there is a variable list made up of index angles and custom macro variables. Then, for each machine tool 2, coordinates are stored in the custom macro variables for each index angle, and the relative movement program is executed based on the custom macro variables in which the coordinates are stored. The procedure for storing coordinates in the custom macro variables for each index angle will be described below.

[0053] 7, the operator inputs and sets a predetermined index angle of index table 10 into control unit 25, and the index angle is stored in memory unit 250 (FIG. 1) of control unit 25 (step S40). Control unit 25 moves spindle 21 in the X and Y directions to position it above push bar 30 (step S41). Control unit 25 transmits to receiver 23 an operation start signal that starts the operation of the extra relative movement of machine tool 2, and the set target angle (step S42).

[0054] When control unit 25 transmits an operation start signal and a target angle to receiver 23, receiver 23 and transmitter 40 start communication, and as shown in Fig. 8, transmitter 40 sequentially transmits the current angle of index table 10 detected by angle detection unit 4 to receiver 23 (step S50). Then, transmitter 40 sequentially transmits the current angle of index table 10 to receiver 23 until the angle detected by angle detection unit 4 from receiver 23 reaches within the allowable range for the index angle (step S51). The tolerance for the index angle refers to the range of error (a few mm) that is permissible for the index angle.

[0055] 7, the control unit 25 moves the spindle 21 in the Z direction to push in the push bar 31 (step S43). As the push bar 31 is pushed in, the index table 10 rotates (step S44).

[0056] As shown in Fig. 8, when the angle detected by the angle detection unit 4 from the transmitter 40 reaches the allowable range for the index angle, the receiver 23 outputs a skip signal (step S52). As shown in Fig. 7, the control unit 25 determines whether this skip signal has been input (step S45). When the skip signal has not been input, the control unit 25 determines whether the push bar 30 has reached the limit coordinate position (steps S45 and S46). The limit coordinate position refers to the coordinate of the spindle 21 up to the limit at which the push bar 30 is allowed to be pushed.

[0057] When the push bar 30 has not reached the limit coordinate position, the control unit 25 causes the spindle 21 to push the push bar 30 and rotate the index table 10 (steps S43, S44) until a skip signal is input (steps S45, S46).

[0058] Furthermore, when the push bar 30 reaches the limit coordinate position even though a skip signal has not been input (step S46), the index table 10 cannot be rotated to the target angle, so the spindle 21 rises to lock the index table 10 (step S51), and the situation is treated as an indexing error (step S52).

[0059] As shown in FIG. 8, when the detected angle of the angle detection unit 4 from the transmitter 40 reaches the allowable range for the index angle, the receiver 23 outputs a skip signal (step S52), and as shown in FIG. 7, the coordinates of the spindle 21 are recorded in temporary macro variables in the memory unit 250 of the control unit 25 (step S47). A temporary macro variable is a custom macro variable configured to record coordinates when a skip signal is input. Then, the spindle 21 is raised and the index table 10 is locked (step S48).

[0060] The control unit 25 determines whether the angle detected by the angle detection unit 4 from the receiver 23 is within an allowable range for the index angle (step S49). If the detected angle is within the allowable range for the index angle, the coordinates of the temporary macro variable recorded in step S47 are recorded in the storage unit 250 of the control unit 25 as a custom macro variable for the index angle (step S50).

[0061] On the other hand, if the detected angle is not within the allowable range of the index angle (step S49), control unit 25 returns to step S42, where it again transmits to receiver 23 an operation start signal to start the extra relative movement operation of machine tool 2 and the set target angle.

[0062] By changing the index angle and performing steps S40 to S52, coordinates can be recorded in custom macro variables for multiple index angles. As a result, coordinates are stored in the custom macro variables in a variable list made up of index angles and custom macro variables. That is, for each machine tool 2, coordinates are stored in custom macro variables for multiple index angles at predetermined angle intervals, and a relative movement program can be executed based on the custom macro variables for a predetermined index angle and their coordinates. Therefore, by executing a relative movement program based on the custom macro variables for a predetermined index angle and their coordinates, the index table 10 can be rotated to a predetermined index angle without feedback control.

[0063] Although the preferred embodiments of the present invention have been described above, the configuration of the present invention is not limited to these embodiments. For example, the following modifications are possible.

[0064] In the above embodiment, the power transmission mechanism 3 of the index device 1 transmits the linear movement of the spindle 21 to the rotation of the index table 10. However, for example, the power transmission mechanism 3 may transmit the rotation of the spindle 21 to the rotation of the index table 10. In the above embodiment, the extra relative movement of the machine tool 2 involves movement of only the spindle 21, but for example, it may also be the case that only the main table 20 moves, or that both the spindle 21 and the main table 20 move. The angle detection unit 4 may be, for example, a proximity sensor, an optical sensor, or a gyro sensor. [Explanation of symbols]

[0065] 1 Indexing device 10 Index Table 11. Housing 2 Machine tools 20 Main Table 21 Spindle 25 Control Unit 3 Power transmission mechanism 30 Push Bar 32 Push bar interlocking mechanism 4 Angle detection unit double work

Claims

1. A machine tool that machines a workpiece indexed by an index device, The indexing device a housing installed on a main table of the machine tool; an index table rotatably supported by the housing and configured to index the workpiece; a power transmission mechanism that transmits an extra relative movement between the spindle and the main table to the rotation of the index table, in addition to the relative movement between the spindle and the main table of the machine tool during machining; an angle detection unit that detects the angle of the index table, The power transmission mechanism includes: a push bar movably supported on the housing; a push bar interlocking mechanism provided in the housing between the push bar and the index table, the push bar interlocking mechanism rotating the index table in conjunction with the push bar; a locking mechanism that locks the index table and unlocks the index table when the push bar moves, The machine tool comprises: A control unit configured to rotate the index table to a set index angle by pushing the push bar by moving the spindle using the detection angle of the angle detection unit as the extra relative movement, The control unit When a skip signal is output when the detected angle reaches within an allowable range for the set index angle, the control unit records the coordinates of the spindle when the skip signal is input in a temporary macro variable, Next, the spindle is moved to lock the index table with the locking mechanism, Next, it is determined whether the detected angle is within the allowable range for the set index angle; when it is determined that the detected angle is within the tolerance range for the set index angle, the coordinates recorded in the temporary macro variables are stored in custom macro variables assigned to the set index angle. A machine tool characterized by:

2. The control unit a storage unit in which a relative movement program for executing the extra relative movement of the machine tool is stored; the relative movement program assigns custom macro variables to a plurality of index angles at predetermined angle intervals in the index table; The control unit is further configured to execute the relative movement program based on a custom macro variable for the index angle whose coordinates are stored, thereby rotating the index table to the index angle. The machine tool according to claim 1.

3. The machine tool further comprises: a receiver configured to receive a signal of the detected angle from the transmitter of the indexing device wirelessly or via a wire, and connected to the control unit; The receiver is further configured to output the skip signal to the control unit when the detected angle reaches within the tolerance range for the set index angle. The machine tool according to claim 1.

4. 1. A method for storing coordinates of a machine tool spindle in a custom macro variable assigned to an indexing angle of an indexing table of an indexing device, comprising: The indexing device a housing installed on a main table of the machine tool; the index table rotatably supported by the housing and indexing a workpiece; a power transmission mechanism that transmits an extra relative movement between the spindle and the main table to the rotation of the index table, in addition to the relative movement between the spindle and the main table during machining; an angle detection unit that detects the angle of the index table, The power transmission mechanism includes: a push bar movably supported on the housing; a push bar interlocking mechanism provided in the housing between the push bar and the index table, the push bar interlocking mechanism rotating the index table in conjunction with the push bar; a locking mechanism that locks the index table and unlocks the index table when the push bar moves, The method comprises: (a) inputting and setting the indexing angle of the index table into a control unit of the machine tool; (b) rotating the index table by the control unit pushing the push bar by moving the spindle using the angle detected by the angle detection unit as the extra relative movement; (c) inputting a skip signal to the control unit when the detected angle reaches a set tolerance range for the index angle; (d) the control unit recording the coordinates of the spindle when the skip signal is input in a temporary macro variable; (e) following step (d), a step of moving the spindle and locking the index table with the locking mechanism; (f) subsequent to step (e), determining whether the detected angle is within the tolerance range for the set index angle; (g) when it is determined that the detected angle is within the tolerance range for the set index angle, storing the coordinate recorded in the temporary macro variable in a custom macro variable assigned to the set index angle. A method characterized by:

5. custom macro variables are assigned to a plurality of index angles in the index table; The method further comprises: performing steps (a) to (g) for each of the plurality of index angles, thereby storing the coordinates of the spindle in each of the custom macro variables; The method of claim 4.

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