JP6002571B2 - Cutting method in machine tool - Google Patents

Description

  The present invention relates to a cutting method for machining a turbine blade in a machine tool, for example.

  Conventionally, for example, when machining a turbine blade, a method as described in Patent Document 1 has been adopted. That is, as shown in FIG. 2, a work spindle 51 having a clamp mechanism 54 capable of gripping the turbine blade W, a tailstock 52 capable of supporting the turbine blade W, and a tool spindle 53 capable of mounting the tool T. Has been adopted. One end of the turbine blade W in the longitudinal direction is gripped by a work spindle 51 so as to be rotatable around the A axis (axis parallel to the horizontal axis), while the other end is supported by a tailstock 52, and a tool spindle The turbine blade W was cut by the tool T by turning the table 53 around a predetermined axis.

JP 7-32247 A

  However, in the above-described conventional cutting method, the support rigidity on the tailstock side is lower than the support rigidity on the work spindle base side, so chatter vibration occurs during machining due to the difference in the support rigidity at both ends of the work. As a result, there is a problem that processing accuracy is lowered.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a cutting method in a machine tool that can improve the machining accuracy as compared with the conventional art.

In order to achieve the above object, the invention described in claim 1 of the present invention includes a pair of work spindles having a clamp mechanism for gripping a work and a servo motor for rotating the spindle, and a tool. A cutting method in a machine tool comprising a mountable tool table, the pair of work spindles and a control device for controlling the operation of the tool table, wherein both ends of the work are placed on the pair of work spindles. It was gripped, as oN the servo motor, in synchronization with the first step of the rotation restricting state where the rotation of the workpiece is restricted to the operation of the servo motor, the servo motor built in the pair of works headstock In the second step of starting machining with the tool on the rotating workpiece and at a predetermined timing from the start of machining to the end of machining, A third step of stopping the operation of the servo motor of the pair of work headstock, and OFF the servo motor remains one workpiece headstock side in a state where both ends of the workpiece were held by both the workpiece headstock Thus, the one work spindle base side is brought into a rotatable state in which the rotation of the work is not restricted by the operation of the servo motor , and due to the strain due to the processing heat generated from the start of the processing to the predetermined timing. A fourth step of eliminating the distortion by automatically rotating the workpiece on the rotatable side, and turning on the servo motor on the one workpiece spindle base side, thereby turning the one workpiece spindle base on after said rotatable state the rotation restricted state by releasing the side, is operated in synchronization with the servo motor again, rotating And executes a fifth step resuming processing by the tool relative to the workpiece.

According to the present invention, both ends of the workpiece are processed by gripping the workpiece spindle table having a clamp mechanism, so that the support rigidity at both ends of the workpiece can be made equal, and chatter vibration is less likely to occur during processing, Improvement in machining accuracy can be expected.
In addition, at a predetermined timing from the start of machining to the end of machining, the servo motor operation of the pair of work spindles is stopped , and one work spindle is held while both ends of the work are held by both work spindles. By turning off the pedestal side servo motor, one work spindle base side is brought into a rotatable state in which the rotation of the work is not restricted by the operation of the servo motor . Then, the workpiece is automatically rotated on the side where it can be rotated by the strain caused by the processing heat generated between the start of processing and a predetermined timing, thereby eliminating the strain. Therefore, distortion caused by the processing heat can be removed during the processing, and the processing accuracy of the workpiece can be improved.

It is explanatory drawing which showed the machining center which processes a turbine blade. It is explanatory drawing which showed the conventional machine tool.

  Hereinafter, a machining center and a cutting method in the machining center according to an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an explanatory view showing a machining center 10 for machining a turbine blade W which is an embodiment of a machine tool.
The machining center 10 includes a pair of work spindles 1a and 1b having a clamp mechanism 4 capable of gripping the turbine blade W, and a tool spindle base 3 on which a tool T can be mounted, and each workpiece spindle 1a and 1b. Incorporates a servo motor 2 for rotating a spindle (not shown). The work spindle 1a is installed in such a posture that the spindle can rotate around the A1 axis parallel to the horizontal axis. On the other hand, the work spindle 1b is opposed to the work spindle 1a and the clamp mechanisms 4, 4. In addition, the main shaft is installed in a posture in which the main shaft can rotate around the A2 axis that is coaxial with the A1 axis.

  The work spindle 1b is slidable in the U-axis direction parallel to the A1 axis and the A2 axis (also the X axis in FIG. 1). Moreover, the tool spindle stock 3 can turn around the B axis parallel to the front and back direction (Y axis direction) in FIG. 1. Further, the tool T is mounted on a spindle (not shown) inside the tool spindle stock 3 and can be rotated together with the spindle by a servo motor (not shown). In addition, the clamp mechanism 4 has a conventionally well-known structure in which, for example, an object is gripped by moving a plurality of claw members back and forth or turning. Then, the rotation operation of the spindle (including ON / OFF of the servo motor 2), the gripping operation of the turbine blade W, the sliding operation of the workpiece spindle table 1b, and the turning operation of the tool spindle table 3 are shown in each workpiece spindle table 1a, 1b. It can be controlled by an NC device (control device) that does not.

  In the machining center 10, one end in the longitudinal direction of the turbine blade W is gripped by the clamp mechanism 4 of the work spindle 1 a, while the other end is gripped by the clamp mechanism 4 of the work spindle 1 b. The servo motors 2 and 2 are turned on (first step). That is, the turbine blade W gripped by the work spindles 1a and 1b is set in a rotation restricted state in which the rotation of the turbine blade W is restricted by the operation of the servo motors 2 and 2. Then, rough machining is performed on the rotating turbine blade W by rotating the tool head stock 3 around the B axis while operating both servomotors 2 in synchronization (second step).

  Next, at the timing (predetermined timing) when the rough machining is finished, the rotation of the spindle in the workpiece spindles 1a and 1b is stopped (third step), and the servo motor 2 of the workpiece spindle 1b is turned off to turn off the workpiece spindle. The spindle of the base 1b is rotatable independently of the servo motor 2. That is, the other end side of the turbine blade W is set in a rotatable state in which the rotation of the turbine blade W is not restricted by the operation of the servo motor 2. Then, although the turbine blade W is distorted by the machining heat generated by the rough machining, the spindle of the work spindle 1b is automatically rotated until the distortion is eliminated (fourth step). Then, after the distortion is eliminated in this way, the servo motor 2 of the work spindle 1b is turned ON again (the rotational state at the other end side of the turbine blade W is released and the rotation restricted state is set), and the work spindle is set. The platform 1a is rotated from the phase after the rough machining is completed, and the workpiece spindle 1b is rotated from the phase after the strain is released, respectively, by rotating the servo motors 2 and 2 of both workpiece spindles 1a and 1b in synchronization with each other to resume machining by the tool T. Then, finish processing is performed on the turbine blade W (fifth step).

According to the machining center 10 as described above, since both ends of the turbine blade W are gripped and processed by the clamp mechanism 4, both ends of the turbine blade W can be processed with the same support rigidity, and chatter vibrations occur during the processing. Therefore, it is possible to expect improvement in processing accuracy.
Further, after the rough machining is finished, the servo motor 2 of one work headstock 1b is turned off, and one end side of the turbine blade W is rotatable. By automatically rotating, after eliminating the distortion, the servo motor 2 of the work head stock 1b is turned on again, and finishing is performed. Therefore, it is possible to remove the strain caused by the processing heat due to the rough processing, and it is possible to manufacture the turbine blade W with high processing accuracy.

  The cutting method according to the present invention is not limited to the aspect of the above-described embodiment, and the configuration related to strain elimination control for eliminating the strain due to machining heat does not depart from the gist of the present invention. The range can be appropriately changed as necessary.

  For example, in the above-described embodiment, the strain relief control is performed such that the servo motor 2 is turned off after the rough machining is finished, and then the finishing process is performed. However, the strain relief such as turning off the servo motor 2 a plurality of times during the rough machining is performed. You may execute the control or execute the strain relief control once during the finishing process, etc., and change the number of times to execute the strain relief control from the start to the end of the process. be able to.

Further, in the above embodiment, running control that turns OFF the servo motor 2 of the workpiece headstock 1b side Upon a rotatable work state and OFF the word over click headstock 1a side servo motor 2 Of course it is also possible.

Furthermore, in the above-described embodiment, the cutting process of the turbine blade has been described. However, the present invention can be applied to cutting processes other than the turbine blade. However, since the turbine blade is generally thin and twisted, the distortion in the rotational direction increases due to thermal displacement, and thus the above cutting is particularly effective for machining the turbine blade.
In addition, although the machining center which is one embodiment of the machine tool is described in the above embodiment, other machine tools such as a multi-tasking machine and a lathe equipped with a tool base for attaching a non-rotating tool instead of a tool spindle base. But there is no problem.

  1a, 1b ··· Workpiece headstock 2 ··· Servo motor (drive means) 3 ··· Tool head stock 4 · · Clamp mechanism 10 · · Machining center (machine tool) W · · · Turbine blade (workpiece)

Claims (1)

A pair of work spindles having a clamp mechanism for gripping a work and a servo motor for rotating the spindle, a tool table on which a tool can be mounted, and the operations of the pair of work spindles and the tool table are controlled. A cutting method in a machine tool provided with a control device,
A first step in which both ends of the work are gripped by the pair of work spindles, the servo motor is turned on, and the rotation of the work is restricted by the operation of the servo motor ;
A second step of synchronously operating the servo motors built in the pair of work spindles and starting machining with the tool on the rotating work;
A third step of stopping the operation of the servo motor in the pair of work spindles at a predetermined timing from the start of processing to the end of processing;
By turning off the servo motor on one work spindle base while both ends of the work are held by both work spindles , the rotation of the work on the one work spindle side is controlled by the servo. By allowing the workpiece to rotate freely on the side that is in the rotatable state due to distortion caused by the processing heat generated from the start of the machining to the predetermined timing, the workpiece is automatically rotated in a state that is not restricted by the operation of the motor . A fourth step of eliminating the strain;
Turn on the servo motor on the one work head stock side, release the rotatable state on the one work head stock side to enter the rotation restricted state, and then operate the servo motor in synchronization again, And a fifth step of resuming machining with the tool on the rotating workpiece.

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