Numerical control device

Abstract

Provided is a numerical control device 1 capable of reducing positional deviation between a focal point position F and a machining point 12. The numerical control device 1 is connected to a machining head 50 that is capable of controlling the focal point position F on the basis of an external input. The numerical control device 1: is provided with a machining nozzle 60 that emits a beam; controls a drive shaft of a machine 3 that uses the beam to machine a cut surface 10 of a workpiece 5; is provided with an interpolation processing unit 22 that performs interpolation on the basis of machining program commands to the drive shaft; and is additionally provided with a focal point position adjusting unit 30 that adjusts the focal point position F such that the focal point position F is a fixed position on the workpiece 5, on the basis of a groove angle θ calculated from a rotational axis position obtained by the interpolation processing unit 22, and a preset distance G0 between the machining nozzle and the workpiece.

Description

Numerical Control Device

[0001] The present disclosure relates to a numerical control device that adjusts the focal point position of a beam based on a change in irradiation distance during groove processing, etc.

[0002] Some machine tools laser process the cut surface of a workpiece by irradiating a laser beam from a processing nozzle toward the cut surface of the workpiece. When performing groove processing with such machine tools, the processing nozzle is tilted relative to the cut surface of the workpiece. Patent Document 1 discloses a technique for irradiating a laser beam from an inclined nozzle.

[0003] The inclination of a conventional processing nozzle 60 when performing groove processing will be described with reference to Figure 1. Figure 1 is a diagram showing a state in which a conventional processing nozzle 60 is inclined. θ indicates the inclination angle. The inclination angle θ is called the groove angle θ. The processing nozzle 60 is attached to a processing head 50. The distance between the tip center 64 of the processing nozzle 60 and the processing point 12 on the cutting surface 10 of the workpiece 5 is called the irradiation distance D. When tilting the processing nozzle 60, the processing nozzle 60 may be tilted while keeping the irradiation distance D constant.

[0004] Processing nozzle 601 is a non-inclined processing nozzle 60. Processing nozzle 602 is an inclined processing nozzle 60. Arrow 130 is a line indicating the trajectory of the inclination of processing nozzle 60. The irradiation distance D of processing nozzle 601 and the irradiation distance D of processing nozzle 602 are both D1, which is the same distance.

[0005] The distance between the tip center 64 of the processing nozzle 60 and the cut surface 10 of the workpiece 5 is called the gap G. When the processing nozzle 60 is tilted while keeping the irradiation distance D constant, the gap G becomes shorter. G2, which is the gap G for the processing nozzle 602, is shorter than G1, which is the gap G for the processing nozzle 601. When the gap G becomes shorter, the processing nozzle 60 approaches the workpiece 5, and there is a risk that the processing nozzle 60 will come into contact with the workpiece 5.

[0006] Therefore, a technique has been proposed to reduce the risk of the tilted processing nozzle 60 coming into contact with the workpiece 5. Patent Document 2 discloses a technique in which, when performing groove processing, the gap G is kept constant, rather than the irradiation distance D, and the processing nozzle 60 is tilted.

[0007] A line 106 indicates the position of the tip center 64 when the gap G is kept constant. Hereinafter, the line 106 will be referred to as the gap reference line 106. The distance between the gap reference line 106 and the cutting surface 10 will be referred to as the reference gap G0.

[0008] The processing nozzle 603 is a processing nozzle 60 that is tilted while maintaining a constant gap G. An arrow 132 is a line indicating the trajectory of the processing nozzle 60 when tilted while maintaining a constant gap G. The gap G in the processing nozzle 601 and the gap G in the processing nozzle 603 are both G1, and are the same distance.

[0009] The distance between the tip center 64 of the processing nozzle 602 tilted with the irradiation distance D kept constant and the tip center 64 of the processing nozzle 603 tilted with the gap G kept constant is called the groove correction amount J. The position of the processing nozzle 603 tilted with the gap G kept constant is the position where the processing nozzle 602 tilted with the irradiation distance D kept constant is moved by the groove correction amount J in the direction of the nozzle central axis 104. The length of the groove correction amount J is the difference between the irradiation distance D2 and the irradiation distance D1.

[0010] JP 2002-011587 A JP 2004-174586 A

[0011] In the above-described technology, the irradiation distance D is extended by performing position correction during groove processing. As a result, the focal point position may shift, resulting in processing defects. This will be explained with reference to FIG. 2. FIG. 2 is a diagram showing an inclined processing nozzle 60. Processing nozzle 601 is a processing nozzle with a groove angle θ of 0 degrees. Processing nozzle 603 is a processing nozzle 60 with a groove angle θ of 45 degrees.

[0012] The focal point position of the laser is assumed to be F. In the processing nozzle 601, the focal point position F coincides with the processing point 12. In contrast, in the processing nozzle 603, the focal point position F does not coincide with the processing point 12. When the processing nozzle 60 is tilted, the irradiation distance D changes. The irradiation distance D2 of the processing nozzle 603 is longer than the irradiation distance D1 of the processing nozzle 601. If the focal point distance L of the laser is the same for the processing nozzle 601 and the processing nozzle 602, the focal point position F will shift relative to the processing point 12 by the amount that the irradiation distance D changes.

[0013] Conventionally, the misalignment between the focal point position F and the processing point 12 was addressed by increasing the laser output, etc. However, with the advent of fiber lasers, it has become necessary to accurately control the focal point position F, i.e., to eliminate the misalignment between the focal point position F and the processing point 12, in order to ensure the quality of the cut surface (by suppressing the generation of dross (burrs), etc., and suppressing the dispersion of heat, etc.). The need to eliminate the misalignment between the focal point position F and the processing point 12 is not limited to fiber lasers; it is the same for carbon dioxide lasers.

[0014] Therefore, an object of the present disclosure is to provide a numerical control device that can reduce the positional deviation between the focal point position and the processing point.

[0015] The numerical control device disclosed herein is a numerical control device connected to a machining head capable of controlling the focal point position based on an external input, and is equipped with a machining nozzle that irradiates a beam, controls the drive axis of a machining machine that uses the beam to machine the cut surface of a workpiece, and is equipped with an interpolation processing unit that performs interpolation based on machining program commands to the drive axis, and further includes a focal point position adjustment unit that adjusts the focal point position so that the focal point position is a constant position on the workpiece based on a groove angle calculated from the rotation axis position determined by the interpolation processing unit and a preset distance between the machining nozzle and the workpiece.

[0016] According to the numerical control device of the present disclosure, it is possible to provide a numerical control device that can reduce the positional deviation between the focal point position and the processing point.

[0017] 1 is a diagram showing a conventional technique, showing a state in which a machining nozzle is inclined; FIG. 2 is a diagram showing the position of the focal point in an inclined machining nozzle; FIG. 3 is a diagram showing an overview of a machine tool; FIG. 4 is a diagram showing an overview of a numerical control device of this embodiment; FIG. 5 is a diagram showing the arrangement of lenses in a machining head; FIG. 6 is a table showing the relationship between the position of the drive axis of a drive lens and the focal point position; FIG. 7 is a graph showing the correlation between the input voltage to the machining head and the focal point position; and FIG. 8 is a diagram for explaining a method of calculating a groove correction amount.

[0018]

[0023] The present disclosure will be described with reference to the accompanying drawings. The present disclosure is not limited to the following embodiments. The present disclosure can be appropriately modified and implemented without departing from the spirit and scope of the present disclosure.

[0019] The configuration of the numerical control device 1 will be described with reference to Figures 3 and 4. Descriptions of matters similar to those described in Figures 1 and 2 will be omitted. Figure 3 is a diagram showing an overview of a machine tool 3. Figure 4 is a diagram showing an overview of the numerical control device 1 of this embodiment. The numerical control device 1 is a device that controls the machine tool 3 by commands based on numerical information.

[0020] The three mutually orthogonal directions are called the X direction, the Y direction, and the Z direction. The X direction and the Y direction are directions parallel to the cut surface 10 of the workpiece 5. The Z direction is a direction perpendicular to the cut surface 10.

[0021] (Machine Tool) As shown in Fig. 3, the machine tool 3 has a nozzle holding portion 52 and a workpiece holding portion 54. The nozzle holding portion 52 is a portion that holds the machining head 50. The workpiece holding portion 54 is a portion that holds the workpiece 5. A machining nozzle 60 is attached to the machining head 50. The numerical control device 1 moves at least one of the nozzle holding portion 52 and the workpiece holding portion 54 via its drive shaft or the like, thereby moving the machining nozzle 60 and the workpiece 5 relative to each other.

[0022] The relative movement includes at least one of relative movement in the X direction, relative movement in the Y direction, relative movement in the Z direction, relative movement around the X direction, relative movement around the Y direction, and relative movement around the Z direction. The relative movement may be performed by moving the processing nozzle 60. Alternatively, the relative movement may be performed by moving the workpiece 5. Alternatively, the relative movement may be performed by moving both the processing nozzle 60 and the workpiece 5.

[0023] In the following description, a case will be described in which the workpiece 5 does not move, but the processing nozzle 60 moves. However, as long as the relative positional relationship between the processing nozzle 60 and the workpiece 5 remains the same, either the processing nozzle 60 or the workpiece 5 may be moved.

[0024] The machine tool 3 irradiates the workpiece 5 with a laser beam 100 from a processing nozzle 60. The machine tool 3 performs laser processing by irradiating the laser beam 100. The direction in which the processing nozzle 60 irradiates the laser beam 100 is referred to as an irradiation direction 102.

[0025] (Numerical Control Device) The numerical control device 1 will be described. As shown in Fig. 4, the numerical control device 1 is a device that controls a machine tool 3. The numerical control device 1 is connected to the machine tool 3. The numerical control device 1 is configured so that a user or the like can input a machining program. The numerical control device 1 controls the machine tool 3 based on the input machining program.

[0026] The numerical control device 1 has a memory unit 20, a program analysis unit 21, an interpolation processing unit 22, and a drive axis control unit 25. The memory unit 20 is a unit that stores a machining program input by a user or the like. The program analysis unit 21 is a unit that analyzes the machining program. The program analysis unit 21 is connected to the memory unit 20. The interpolation processing unit 22 is a unit that performs interpolation based on the results of the analysis by the program analysis unit 21 (machining program commands to the drive axis). The interpolation processing unit 22 determines the rotation axis position of the machining nozzle 60. The interpolation processing unit 22 is connected to the program analysis unit 21.

[0027] (Bevel Angle Calculation Unit) The numerical control device 1 further includes a bevel angle calculation unit 23 and a light-focusing point position adjustment unit 30. The bevel angle calculation unit 23 is a part that calculates the bevel angle θ from the rotation axis position obtained by the interpolation processing unit 22.

[0028] (Light Focus Position Adjustment Unit) The light focus position adjustment unit 30 is a part that adjusts the light focus position F so that the light focus position F becomes a fixed position on the cut surface 10 of the workpiece 5, particularly the processing point 12 on the cut surface 10, based on the bevel angle θ calculated by the bevel angle calculation unit 23 and the preset distance between the tip center 64 of the processing nozzle 60 and the cut surface 10 of the workpiece 5, i.e., the reference gap G0. The light focus position adjustment unit 30 is connected to the processing head 50.

[0029] The drive axis control unit 25 controls the driving of the nozzle holding unit 52 and the workpiece holding unit 54. The drive axis control unit 25 is connected to the interpolation processing unit 22 and the groove angle calculation unit 23. The drive axis control unit 25 controls the driving of at least one of the nozzle holding unit 52 and the workpiece holding unit 54 based on the result of interpolation performed by the interpolation processing unit 22, the groove angle θ calculated by the groove angle calculation unit 23, and the groove correction amount J calculated from the reference gap G0. For example, when performing groove machining, the drive axis control unit 25 tilts the machining nozzle 60 in accordance with the groove angle and moves the machining nozzle 60 by the groove correction amount J in the direction of the nozzle center axis 104.

[0030] (Outline of Adjustment of Focus Point Position) In the numerical control device 1 of this embodiment, the focus point position F is adjusted based on the groove correction amount J during groove machining so that the focus point position F is at a fixed position on the workpiece 5, in particular the machining point 12. The focus point position adjustment unit 30 adjusts the focus point position F based on the groove angle θ, the reference gap G0, etc. The focus point position F is adjusted by driving the axis of the drive lens by the numerical control device 1 or by inputting a signal to the machining head 50.

[0031] This allows the light condensing point position F to be positioned at a fixed position on the workpiece 5 regardless of the groove angle θ, thereby enabling stable machining.

[0032] The external inputs to the machining head 5 include inputs such as pulse signals for driving the axis of the drive lens, and inputs such as current and voltage for changing the focal point position, which are input from the numerical control device 1 to the machining head 5.

[0033] 2, tilting the processing nozzle 60 increases the irradiation distance D. Therefore, if the focal point distance L is the same before and after tilting, the focal point position F will be shifted from the processing point 12. Specifically, the focal point position F will be located just before the laser 100 reaches the processing point.

[0034] Therefore, the focal point position F is adjusted according to the irradiation distance D. In other words, the focal point distance L is adjusted according to the change in the groove angle θ. This makes it possible to position the focal point position F on the cut surface 10 of the workpiece 5 even when the processing nozzle 60 is tilted.

[0035] (Mechanism for changing the focal point position) An example of a mechanism for changing the focal point position will be described with reference to FIG. 5. FIG. 5 is a diagram showing an outline of the arrangement of lenses inside the machining head 50. Inside the machining head 50, a first fixed lens 71, a movable lens 73, and a second fixed lens 72 are arranged along the Z direction. The movable lens 73 can move in the direction of arrow 120. The movable lens 73 can move in the positive and negative directions of the Z axis shown in FIG. 5. The focal point position F moves in the direction of arrow 122 by moving the movable lens 73 in the direction of arrow 120.

[0036] 5, a shaft 75 is attached to the movable lens 73 for driving the movable lens 73. The movable lens 73 can be moved by driving the shaft 75, for example.

[0037] (Position of the movable lens and the focal point position) By moving the movable lens 73 in the negative direction of the Z axis, the focal point position F can be moved in the negative direction of the Z axis. For example, the focal point position F can be moved from F1 to F2. In other words, the focal point distance L can be extended from distance L1 to distance L2.

[0038] The movable lens 73 illustrated in Fig. 5 is a convex lens. The movable lens 73 is not limited to a convex lens. By changing the type of movable lens 73 or the refractive index of the lens, the relationship between the position of the movable lens 73 and the focal point position F can be changed.

[0039] The movable lens 73 can be moved, for example, by an external input from the numerical control device 1 to the machining head 50. For example, the shaft 75 supporting the movable lens 73 can be driven by inputting a pulse signal from the numerical control device 1 to the machining head 50. Another example is control by signal input (such as voltage or current) from the numerical control device 1 to the machining head 50. Control by signal input to the machining head 50 is, for example, control that changes the focal point position F by changing the input voltage to the machining head 50. The means for controlling the focal point position F are not limited to the above-mentioned means. If a machining head 50 that can control the focal point position F based on an external input (such as NC control) is connected to the numerical control device 1, the focal point position F can be controlled.

[0040] (Ground Correction Amount Calculation Unit) The above description has been given as an example of a change in irradiation distance D due to a change in the groove angle θ of the processing nozzle 60. In this case, a ground correction amount calculation unit may be provided in the numerical control device 1. The ground correction amount calculation unit calculates a ground correction amount J from the gap G specified by the processing program and the ground angle calculated by the ground angle calculation unit 23. The ground correction amount J is the correction amount when correcting the processing nozzle 60 in the direction of the nozzle central axis 104. The light-focus point position adjustment unit 30 may adjust the ground point position based on the ground correction amount J.

[0041] The adjustment of the focal point position by the focal point position adjusting unit 30 is not limited to cases where the included angle θ of the processing nozzle 60 changes. For example, the focal point position adjusting unit 30 adjusts the focal point position even when the irradiation distance D changes in gap control using a gap sensor to keep the gap G constant, in other words, profile control. For example, this occurs when the cut surface 10 of the workpiece 5 is uneven. This is because if the irradiation distance D changes, the focal point position F will deviate from a fixed position on the workpiece 5.

[0042] (Control Based on a Table) The determination of the control value in the adjustment of the focal point position F by the numerical control device 1 will be described. First, the determination of the value based on a table will be described. Fig. 6 is a table showing the relationship between the position of the shaft 75 that drives the drive lens 73 and the focal point position F.

[0043] The relationship between the movement of the axis 75 that drives the drive lens 73 by the numerical controller 1 and the focal point position F is stored as a table inside the numerical controller 1. Specifically, this table converts the distance to which the focal point position F is to be moved into the amount of movement of the axis 75. By storing such a table in the numerical controller 1, it is possible to know, for example, that if the focal point position F is to be moved by -0.8 mm, the axis 75 should be moved by -1.0 mm. Furthermore, if the focal point position to which the focal point is to be moved is not recorded in the table, the amount of movement of the axis 75 may be calculated by proportional calculation or the like from the values ​​of the focal point positions before and after the desired position.

[0044] (Control Using Correlation Graph) A control value may be determined based on a correlation graph between the input voltage to the machining head 50 and the focal point position F. Fig. 7 is a graph showing the correlation between the input voltage to the machining head 50 and the focal point position F. The horizontal axis of Fig. 7 represents the input voltage (V) to the machining head 50. The vertical axis of Fig. 7 represents the focal point position F (mm).

[0045] For example, when the groove angle is 0°, the light-focus position F is at 0 mm (default position). When the groove angle is 45° and the groove correction amount J is 1.0 mm, a voltage is input to the processing head 50 so that the light-focus position F becomes −1.0 mm.

[0046] 7, when the focal point position F is at 0 mm, the input voltage to the processing head 50 is 4.06 V. When the focal point position F is at -1.0 mm, the input voltage to the processing head 50 is 4.687 V. Therefore, the input voltage to the processing head 50 is changed from 4.06 V to 4.687 V. This allows the focal point position F to be positioned on the cutting surface 10.

[0047] When the irradiation distance D is calculated from the rotation axis position obtained by the interpolation processing unit 22, the focus position adjustment unit 30 can adjust the focus position F based on the irradiation distance D and the reference gap amount G0. In addition, in the case of groove processing, the groove correction amount that serves as the basis for adjusting the focus position F can be obtained as follows.

[0048] (Determining groove correction amount) A method for calculating the groove correction amount J from the groove angle θ will be described. FIG. 8 is a diagram for explaining a method for calculating the groove correction amount J. Processing nozzle 601 indicates the processing nozzle 60 when perpendicular to the surface. Processing nozzle 602 indicates the processing nozzle 602 when groove processing is performed. The groove angle is θ. When the tip center 64 of the processing nozzle 60 is maintained at a constant distance from the cut surface 10 of the workpiece 5 during groove processing, G, D, and θ in FIG. 8 are related by the following formula: D = G / (cos θ) G is the gap and is assumed to be constant. D is the irradiation distance.

[0049] The groove correction amount J is D-G. That is, J = G / (cos θ)-G. Here, G is a predetermined so-called reference gap amount G0. By inputting the reference gap amount G0 into the formula, the groove correction amount J can be calculated.

[0050] Once the groove correction amount J is determined, specific values ​​for driving the shaft 75 of the drive lens 73 or for controlling by inputting a signal to the machining head 50 can be determined using any of the methods described above.

[0051] The present disclosure is not limited to the above-described embodiments and modifications, and includes modifications and improvements within the scope of achieving the object of the present disclosure.

[0052] The following additional notes are provided regarding the above-described embodiment and modifications.

[0053] (Supplementary Note 1) A numerical control device (1) connected to a machining head (50) capable of controlling a focal point position (F) based on an external input, the numerical control device comprising: a machining nozzle (60) that irradiates a beam; an interpolation processing unit (22) that controls a drive axis of a machining (3) machine that processes a cut surface (10) of a workpiece (5) with the beam and performs interpolation based on a machining program command to the drive axis; and a focal point position adjustment unit (30) that adjusts the focal point position (F) so that the focal point position (F) is a constant position on the workpiece (5) based on a groove angle (θ) calculated from a rotation axis position determined by the interpolation processing unit (22) and a preset distance between the machining nozzle (60) and the workpiece (5).

[0054] (Note 2) In the above-described numerical control device (1), the processing machine (3) performs at least bevel processing to incline the cut surface (10), and further includes a bevel angle calculation unit (23) that calculates a bevel angle (θ) from the rotation axis position, and the light-focus point position adjustment unit (30) adjusts the light-focus point position (F) further based on the bevel angle (θ).

[0055] (Note 3) In the above-described numerical control device (1), the focal point position adjusting unit (30) controls the focal point position (F) by driving the axis of a lens provided in the processing head (50) or by inputting a signal to the processing head (50).

[0056] DESCRIPTION OF SYMBOLS 1 Numerical control device 3 Processing machine 5 Workpiece 10 Cut surface 12 Processing point 22 Interpolation processing unit 23 Groove angle calculation unit 24 Groove correction amount calculation unit 30 Focus point position adjustment unit 50 Processing head 60 Processing nozzle 64 Tip center 52 Nozzle holding unit 54 Workpiece holding unit 71 First fixed lens 72 Second fixed lens 73 Driving lens 75 Axis 100 Laser D Irradiation distance G0 Reference gap F Focus point position G Gap J Groove correction amount L Focus point distance θ Groove angle

Claims

1. A numerical control device connected to a machining head capable of controlling a focal point position based on an external input, comprising a machining nozzle that irradiates a beam, controls a drive axis of a machining machine that uses the beam to machine the cut surface of a workpiece, and comprises an interpolation processing unit that performs interpolation based on machining program commands for the drive axis, and further comprises a focal point position adjustment unit that adjusts the focal point position so that the focal point position is a constant position on the workpiece based on a groove angle calculated from the rotation axis position determined by the interpolation processing unit and a preset distance between the machining nozzle and the workpiece.

2. The numerical control device according to claim 1, wherein the processing machine at least performs groove processing to incline the cut surface, and further comprises a groove angle calculation unit that calculates a groove angle from the rotation axis position, and the focal point position adjustment unit adjusts the focal point position further based on the groove angle.

3. A numerical control device according to claim 1 or 2, wherein the focal point position adjustment unit controls the focal point position by driving an axis of a lens provided on the processing head, or by inputting a signal to the processing head.

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