Method and device for determining vibration-relief position in machine tool

Abstract

To provide a swing stop position determination method and a device in a machine tool that can determine an installation position of swing stop before actually performing machining.SOLUTION: A swing stop position determination device in a machine tool comprises: a vibrating device 12 which vibrates a workpiece W; and a vibration sensor 13 which measures vibration of a vibrated workpiece W. A numerical control device 7 is provided with vibration analyzing means which identifies a strong vibration point measured by the vibration sensor 13 and sets the strong vibration point as a swing stop position.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method and device for determining a vibration rest position in a machine tool, which determines an appropriate installation position for a vibration rest that is provided in the machine tool and grips the middle part of a workpiece. [Background technology]

[0002] Machine tools machine workpieces into preset shapes and dimensions by rotating or fixing a cutting tool and pressing it against the workpiece. One of the elements necessary for machining is the rigidity of the machine, but the rigidity of the workpiece is also an important factor. If the rigidity of the workpiece is weak and chatter occurs during machining, this can cause damage to the tool or machine.

[0003] In machine tools, when machining long workpieces that are prone to chatter, a vibration suppressor is used as a workpiece chatter suppression device that grips the middle part of the workpiece to reduce runout and vibration of the workpiece (for example, Patent Document 1).

[0004] When cutting a long workpiece using a machine tool equipped with a vibration rest, the vibration rest is usually moved to a position where vibration will not occur, and machining begins with the workpiece grasped. However, with initial workpieces, for example, it is often not possible to determine which position on the workpiece the vibration rest should grasp, so first a try is made in a position where vibration will not occur, and if vibration occurs as a result, the position is changed and machining is resumed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-266268 Summary of the Invention [Problem to be solved by the invention]

[0006] Changing the vibration rest position has the problem of reducing machining efficiency. Also, while it is possible to increase the number of vibration rest installation positions to prevent chatter, this can result in problems such as longer machining times. To solve these problems, it is desirable to determine the vibration rest installation positions before machining begins.

[0007] The present invention has been made in consideration of the above-mentioned problems of the conventional technology, and its object is to provide a method and device for determining the vibration rest position in a machine tool, which can determine the installation position of the vibration rest before actually performing machining. [Means for solving the problem]

[0008] The vibration-proof position determination method for a machine tool of the present invention is a method for determining a vibration-proof position when machining a workpiece based on a machining program in a machine tool, the method comprising the steps of: vibrating the workpiece; measuring the vibration of the vibrated workpiece with a vibration sensor; The position where the amplitude is the largest in the workpiece, or the center of the range where the amplitude exceeds the threshold. This is the vibration prevention position.

[0009] The vibration-proof position determining device for a machine tool of the present invention is a device for determining a vibration-proof position when machining a workpiece based on a machining program in a machine tool, and includes a vibration excitation device for exciting a workpiece, a vibration sensor for measuring the vibration of the excited workpiece, and a vibration sensor for measuring the vibration of the workpiece measured by the vibration sensor. Based on the amplitude at the workpiece Steady rest position Decide and vibration analysis means for Crate , The position where the amplitude is the largest or the center of the range where the amplitude exceeds the threshold is set as the vibration stop position. It is something.

[0010] According to the method and device for determining the vibration rest position in a machine tool of this invention, the rigidity of the workpiece can be measured by vibrating the workpiece and measuring the vibration with a vibration sensor, and this information can be used to determine the machining conditions, determine the optimal support force and support position of the vibration rest, and judge whether the workpiece is supported properly. The measurement of the workpiece rigidity can be performed automatically without the intervention of an operator before machining, and by determining the installation position of the vibration rest before actual machining, the optimal machining method for the workpiece can be determined, improving machining efficiency and preventing damage to the tool or machine due to chatter.

[0011] It is preferable to reflect the obtained vibration-reducing position in the machining program. In this way, a series of operations including the determination of the vibration-reducing position is reflected in the machining program, which makes it possible to further improve machining efficiency.

[0012] The workpiece can be vibrated by an appropriate vibrating device, which may be provided either inside or outside the machine tool, taking into consideration machining efficiency.

[0013] The vibration excitation device is preferably an articulated robot. Articulated robots are often used in machine tools, and adding a vibration excitation function to such an articulated robot makes it possible to vibrate a workpiece without installing a separate vibration excitation device. [Effects of the Invention]

[0014] According to the method and device for determining the vibration rest position in a machine tool of this invention, the appropriate vibration rest installation position is determined before actual machining is performed without the intervention of an operator, thereby improving machining efficiency and preventing damage to the tool or machine due to chatter. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a front view schematically showing the hardware configuration of a method and device for determining an anti-vibration position in a machine tool according to the present invention; [Figure 2]1 is a block diagram showing a control portion of a method and apparatus for determining a vibration rest position in a machine tool according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0017] As shown in FIG. 1, a machine tool (e.g., a horizontal lathe) (1) to which the method and device for determining a vibration stop position according to the present invention is applied includes a tool post (2) to which a cutting tool (2a) for cutting a workpiece (W) is attached and which is movable in both longitudinal and radial directions, a spindle (3) that rotates the workpiece (W), a chuck (4) that supports the workpiece (W) and is attached to the spindle (3), a tailstock (5) that presses the workpiece (W) in the longitudinal direction with a given force, one or more vibration stoppers (6) that are movable parallel to the spindle (3) and reduce runout and vibration of the workpiece (W), and a numerical control device (7) that controls the tool post (2), spindle (3), chuck (4), tailstock (5), and vibration stopper (6).

[0018] The above-described configuration has been conventionally provided in machine tools (1), and with this machine tool (1), when cutting a long workpiece (W) that is prone to chatter (for example, a workpiece with an L / D of 10 or more) or a thin-walled flange-shaped workpiece, chatter can be prevented by gripping the longitudinal middle part of the workpiece (W) with the vibration stopper (6), and the workpiece (W) can be machined.

[0019] The vibration prevention position determining method and device (11) according to the present invention further comprises, as hardware components, a vibration applying device (12) and a vibration sensor (13) which have not been used conventionally.

[0020] The vibration device (12) is used to vibrate the workpiece (W) and is equipped with an actuator section (12a) that can move parallel to the longitudinal direction of the workpiece (W) and a vibration section (12b) that can move in a direction perpendicular to the longitudinal direction of the workpiece (W).

[0021] The vibration sensor (13) samples the vibration of the workpiece (W) caused by the vibration applied by the vibration device (12), and the vibration of the workpiece (W) is processed by the numerical control device (7).

[0022] As shown in FIG. 2, the numerical control device (7) is provided with a cutting control section (14) that performs numerical control of the main body (1a) of the machine tool (1), such as the tool post (2), spindle (3), chuck (4), tailstock (5), and vibration rest (6), based on a machining program (8), and a feed axis control section (15) that controls the feed axis (6a) of the vibration rest (6), which is directly related to the vibration rest position determining method and vibration rest position determining device (11) of the present invention.

[0023] The numerical control device (7) further includes a vibration analysis unit (vibration analysis means) (16) that analyzes vibration data from the vibration sensor (13) added as the vibration prevention position determining method and vibration prevention position determining device (11) of the present invention.

[0024] The vibration analysis unit (16) processes the vibration of the workpiece (W) obtained by the vibration sensor (13) to determine the vibration prevention position, and changes the machining program (8) based on the obtained vibration prevention position via the machining program change unit (17). As a result, the feed axis (6a) of the vibration prevention unit (6) is controlled via the feed axis control unit (15) of the machining program (8) in which the vibration prevention position has been changed.

[0025] When machining using the machine tool (1) described above, first, the workpiece (W) is held by the chuck (4) and pushed by the tailstock (5) to create a chucking state. Conventionally, the machine tool (1) is started in this state and machining begins, but in the machine tool (1) equipped with the vibration-proof position determination device (11) described above, the workpiece (W) is vibrated by the vibration excitation device (12) before machining. Then, the vibration of the workpiece (W) caused by the vibration excitation is sampled by the vibration sensor (13) and stored in a database in the numerical control device (7).

[0026] The vibration position and strength of the vibration applied by the vibration device (12) can be arbitrarily set based on the model data stored inside the machine tool (1), and the setting can be made on the display (18).

[0027] After the vibration of the workpiece (W) is stored in the database, the vibration analysis unit (16) identifies the areas of the workpiece (W) where vibration is large (i.e., areas of the workpiece (W) that are weak and prone to vibration), and the installation position of the vibration stopper (6) is determined before actual machining.

[0028] Specifically, the position where the vibration stopper (6) is installed is determined by determining the position on the workpiece (W) where the amplitude is largest, and the vibration stopper (6) is installed at the position where the amplitude is largest or in the center of the range where the amplitude exceeds the threshold value.

[0029] Thus, according to the machine tool 1 of this embodiment, the workpiece W is vibrated, the vibration of the vibrated workpiece W is measured by the vibration sensor 13, the locations where the measured vibration amplitude is large are identified, this is reflected in the machining program 8, and the locations are grasped by the vibration rest 6, thereby minimizing the number of times the vibration rest 6 is used and improving machining efficiency. Furthermore, by incorporating automation using a robot or the like, it is possible to further improve machining efficiency.

[0030] The vibration device (12) may be provided on the tool post (2), and in a machine tool (1) having multiple tool posts (2) in the same machining space, each of the multiple tool posts (2) may be provided with a vibration device (12).

[0031] The vibration position and vibration strength may not be set using the display (18), but may be set by recognizing the longitudinal position and outer diameter of the workpiece (W) from the information in the machining program (8) and operating the machining program (8).

[0032] The vibration device (12) may be a dedicated actuator installed inside the machine tool (1), but is not limited to this, and the vibration device (12) and vibration sensor (13) may be installed at an appropriate position inside or outside the machine tool (1).

[0033] The vibration device 12 may be an articulated robot installed inside or outside the machine tool 1. The articulated robot is a robot with multiple degrees of freedom in which multiple links are connected via joints, and is installed in a machining chamber to perform tasks such as transporting a workpiece. By adding a function to vibrate the workpiece W, it becomes possible to arbitrarily set the direction and position of vibration without interfering with components of the machine tool 1, such as the tool post 2, and it is possible to more accurately measure the rigidity of the workpiece W.

[0034] In the above machine tool (1), it is preferable to issue an alarm and stop machining when the vibration result exceeds a threshold value that is determined to be abnormal and is arbitrarily set. It is also preferable to install a calibration unit inside the machine tool (1) to confirm that the value of the vibration sensor (13) in response to the vibration is normal, and to have a function to check for the presence or absence of a malfunction by performing calibration periodically. [Explanation of symbols]

[0035] (1):Machine tools (6): Tremor (7): Numerical control device (8): Processing program (11): Steady rest position determination device (12): Vibration device (13): Vibration sensor (16): Vibration analysis section (vibration analysis means)

Claims

1. A method for determining a position of a vibration rest when machining a workpiece based on a machining program in a machine tool, comprising: A method for determining an anti-vibration position in a machine tool, in which a workpiece is vibrated, the vibration of the vibrated workpiece is measured with a vibration sensor, and the position on the workpiece where the amplitude is greatest or the center of the range where the amplitude exceeds a threshold is set as the anti-vibration position.

2. 2. The method for determining a vibration rest position in a machine tool according to claim 1, wherein the obtained vibration rest position is reflected in a machining program.

3. 3. A method for determining a vibration prevention position in a machine tool according to claim 1, wherein the vibration of the workpiece is applied by a vibration applying device provided inside or outside the machine tool.

4. 4. The method for determining a vibration prevention position in a machine tool according to claim 3, wherein the vibration excitation device is an articulated robot.

5. A device for determining a position of a vibration rest when machining a workpiece based on a machining program in a machine tool, A vibration prevention position determination device for a machine tool, comprising: a vibration excitation device that vibrates a workpiece; a vibration sensor that measures the vibration of the excited workpiece; and a vibration analysis means that determines a vibration prevention position based on the amplitude of the workpiece measured by the vibration sensor, wherein the position where the amplitude is greatest or the center of the range where the amplitude exceeds a threshold value is determined to be the vibration prevention position.

6. 6. The vibration-reducing position determining device for a machine tool according to claim 5, wherein the obtained vibration-reducing position is reflected in a machining program.

7. 7. The vibration-proof position determining device for a machine tool according to claim 5, wherein the vibration applying device is provided inside or outside the machine tool.

8. 8. The vibration prevention position determining device for a machine tool according to claim 7, wherein the vibration excitation device is an articulated robot.

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