JPH0156877B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an improvement in a laser processing machine, and more particularly, it relates to an improvement in a laser beam processing machine, and more particularly, it relates to an improvement in a laser beam processing machine, and more particularly, it relates to an improvement in a laser beam processing machine, and more particularly, it relates to an improvement in a laser beam processing machine, and more particularly, it relates to an improvement in a laser beam processing machine, and more particularly, it relates to an improvement in a laser processing machine, and more particularly, it relates to an improvement in a laser beam processing machine, and more particularly, it relates to an improvement in a laser beam processing machine, and more particularly, it relates to an improvement in a laser beam processing machine, and more particularly, it relates to an improvement in a laser processing machine. The present invention relates to a laser processing machine in which the amount of offset of a processing head is changed in accordance with the spot radius of a laser beam, that is, the spot diameter.

[Prior art]

FIG. 2 is a configuration diagram showing the principle of a laser processing machine. In the figure, 1 is a laser oscillator, 2 is a plane mirror, 3 is a processing head, 4 is a lens that is a condensing device, 5 is a laser beam, and 6 is a workpiece.The plane mirror 2 and processing head 3 are fixed to a housing. , a laser beam 5 output from a laser oscillator 1 is reflected by a plane mirror 2, and a lens 4 provided in a processing head 3
A workpiece 6 is placed near the focal point of the laser beam 5 that is incident on the lens 4 and focused by the lens 4 .

Next, the operation will be explained. In the configuration shown in FIG. 2, when the laser beam 5 focused by the lens 4 is irradiated onto the workpiece 6 near the focal position, the laser beam 5 is absorbed by the surface layer of the workpiece 6 and is converted into thermal energy. The workpiece 6 is melted and processed such as drilling and cutting. For example, if the position of the processing head 3 is moved from A shown in the figure to B shown by a broken line while irradiating the workpiece 6 with the laser beam 5, the length of the trajectory of the laser beam 5 irradiated onto the workpiece 6, that is, the It is possible to carry out a fusing process with a length corresponding to L.

However, as shown in FIG.
Since the laser beam 5 oscillated from the laser beam 5 has a characteristic of having a divergence angle indicated by θ, the beam diameter of the laser beam 5 increases according to the length of the distance from the laser oscillator 1.

On the other hand, if the beam diameter of the laser light incident on the lens changes, the way the light is focused after passing through the lens changes.

FIG. 4 is an explanatory diagram for explaining the state of the laser light incident on the lens. Generally, the beam waist of the Gaussian mode laser light incident on the lens 4, that is, the laser light whose intensity distribution is Gaussian. The radius W ₀ , the distance d ₁ between the lens 4 and the beam waist position, the focal length f of the lens 4, and the beam radius W ₁ at the distance d ₂ from the lens of the laser light that has passed through the lens are expressed by equation (1). There is.

W ₁ = W ₀ d ₂ / d ₁ [1 + Z ² / ₀ / d ² / ₁ ] ^-1/2・[1 + d ⁴ / ₁
/Z ² / ₀ (1 + Z ² / ₀ /d ² / ₁ ) ² × {1 / d ₂ -1 / f + 1
/d ₁ [1+(Z ² / ₀ /d ² / ₁ )]} ² ] ^1/2 ………(1) where Z ₀ ≡πW ² / ₀ /λ λ is the beam wavelength and the beam waist radius W ₀
and its position are determined by the structure within the oscillator 1.

Hereinafter, d ₁ will be referred to as the distance from the oscillator 1. Also, W ₁ on the workpiece will be called the spot radius.

In addition, in FIG. 4, 1a and 1b are mirrors.

Figure 5 shows the laser beam at position A in Figure 3.
The difference in light focusing by the lens 4 is shown when the laser beams at positions a and B are shown as 5b. That is, the laser beam 5a having a large diameter is narrowed to a smaller beam diameter at a position closer to the lens than the laser beam 5b having a narrower diameter.

FIG. 6 is a perspective view showing the principle of a processing machine in which a processing head performs two-dimensional scanning. In FIG. 6, the same parts as in FIG. 2 are designated by the same reference numerals. 2a, 2b, and 2c are plane mirrors, 7 is a processing table, and 8X is an X-axis moving table, which is driven by a drive device and moves in the X-axis direction, which is the longitudinal direction of the processing table 7. 8Y is a Y-axis moving table, to which the processing head 3 is attached, and is driven by a drive device to move on the X-axis moving table 8X. Therefore, by controlling and moving the X-axis moving table 8X and the Y-axis moving table 8Y with an NC device, the machining head 3 can be moved two-dimensionally, and an arbitrary two-dimensional shape 10 can be processed. It is possible to do this.
Note that 9X and 9Y indicate guide rails for the movable table.

In the processing machine shown in FIG. 6, the distance d ₁ from the laser oscillator 1 is determined by the sum of the X and Y coordinates.

As described above, as the machining head 3 moves and the aforementioned distance _d1 changes, the spot radius changes.
W ₁ changes.

By the way, in a laser processing machine, the spot radius _W1 has a certain size, so the processing head 3 is shifted by the value of this radius, that is, an offset is applied to obtain the desired size. During machining, the offset amount registered in the NC device is constant, so if the spot radius _W1 of the laser beam 5 changes during machining, it will deviate from the set offset amount, causing the cutting width to dig into the product or make a larger cut. This results in the problem of dryness.

In other words, when cutting out, for example, a square from the workpiece 6, the spot radius is
An extreme illustration of the state of change in W ₁ is shown in Figure 7. Even though the program of the NC equipment is designed to cut out a square, the actually cut out product 11 is not accurate. It has the disadvantage that it does not form a perfect square. Note that 12 indicates the locus of the spot of the laser beam 5, and the dashed line 13 indicates the locus of movement of the processing head 3.

[Summary of the invention]

This invention was made to solve the above-mentioned drawbacks, and the spot radius of the laser beam on the workpiece changes as the optical path length from the laser oscillator to the condensing device of the processing head changes. Another object of the present invention is to provide a laser processing machine equipped with an offset amount control device that changes the offset amount of a processing head in accordance with the spot diameter.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a block diagram showing an embodiment of an offset amount control device according to the present invention. In FIG. 1, 21 is an optical path length calculation circuit, which calculates the distance d ₁ from the laser oscillator 1 based on the X and Y movement amount of the processing head 3, and 22 is a spot diameter calculation circuit, which is calculated using the formula (1). This is a circuit for calculating the spot radius _W1 of the laser beam 5 on the workpiece 6.

23a and 23b are adder circuits, 24 is an X-axis motor drive circuit, which outputs a drive signal to the drive motor of the X-axis moving table 8X, and 25 is a Y-axis motor drive circuit, for driving the Y-axis moving table 8Y. This is a circuit that outputs a drive signal to the motor.

Next, the operation will be explained.

The amount of movement of processing head 3 in the X and Y directions is NC.
Since it is detected for positioning by the apparatus, the distance d ₁ from the laser oscillator 1 is calculated by the optical path length calculation circuit 21 based on this X and Y movement amount. This calculation result is input to the spot diameter calculation circuit 22, which calculates the spot radius _W1 using equation (1). Note that the distance d ₂ is constant. That is, it is assumed that the processing head 3 does not move vertically relative to the workpiece 6.

Next, the spot diameter calculation circuit 22 outputs the calculated value of the spot radius _W1 as an offset amount. The following operates according to the normal offset function of the NC device. First, this offset amount is input to the adder circuit 23a. Further, the amount of X-axis movement according to the command of the program of the NC device is also input to the addition circuit 23a. The X component of the offset amount is added to or subtracted from the X-axis movement amount by the adding circuit 23a depending on whether the direction of offset is applied, for example, to the right or to the left depending on the position to be processed. The output of the adder circuit 23a is input to the X-axis motor drive circuit 24, and the X-axis movable base 8X is offset by the drive signal of the drive motor of the X-axis movable base 8X output from the X-axis motor drive circuit. Move to position.

On the other hand, the offset amount is also input to the addition circuit 23b, and the Y-axis movement amount according to the command of the program of the NC device is also input to the addition circuit 23b. Then, depending on the position to be processed, the direction in which the offset is applied is set, for example, upward or downward, so that the Y component of the offset amount is added or subtracted from the Y-axis movement amount by the addition circuit 23b. Addition circuit 2
The output of 3b is input to the Y-axis motor drive circuit 25, and the drive signal of the drive motor of the Y-axis moving table 8Y output from the Y-axis motor drive circuit 25 causes the Y-axis
The shaft moving table 8Y moves to the offset position.

As described above, as the spot radius _W1 changes, the offset amount can also be changed, so that even if the optical path length changes, precise processing can be performed with the desired dimensions.

Also, when the machining head 3 moves up and down with respect to the workpiece 6, a device to measure the distance between the machining head 3 and the workpiece 6 should be attached, and that value should be substituted into _d2 in equation (1). For example, since the spot radius _W1 can be determined, the offset amount can be controlled in the same way.

If there is collimation in the middle of the optical path, the appropriate equation for beam propagation may be used instead of equation (1).

〔Effect of the invention〕

As can be seen from the above description, according to the present invention, a laser beam transmitted from a laser oscillator is focused by a condensing device installed in a processing head, and is irradiated onto a workpiece placed on a processing table. In a laser processing machine that performs processing by moving the processing head, the spot radius of the laser beam on the workpiece changes as the optical path length from the laser oscillator to the light condensing device changes, that is, the spot diameter. Since the offset amount control device is provided to change the offset amount of the machining head according to the processing head, even if the spot diameter of the laser beam changes during machining, the offset amount also changes accordingly, so that the offset amount can be adjusted to the spot radius. The cutting width will not deviate from the amount, and the cutting width will not dig into the product or cut the product too large.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing an embodiment of the offset amount control device in this invention, Fig. 2 is an explanatory diagram for explaining the principle of a laser processing machine, and Fig. 3 is an explanatory diagram for explaining the propagation characteristics of laser light. Figure 4 is an explanatory diagram of the state of the laser beam incident on the lens.
The figure is an explanatory diagram to explain the focusing ability of laser light.
FIG. 6 is a perspective view showing the principle of a laser beam machine in which a machining head is two-dimensionally scanned, and FIG. 7 is an explanatory view for explaining the state of machining with a conventional laser beam machine. In the figure, 1 is a laser oscillator, 2, 2a, 2b, 2
c is a plane mirror, 3 is a processing head, 4 is a lens (concentrator), 5, 5a, 5b is a laser beam, 6 is a workpiece, 7 is a processing table, 8X is an X-axis moving table, 8Y
is the Y-axis moving table, 9X, 9Y are guide rails, 10
is the figure to be processed, 11 is the cut out product, 12 is the spot trajectory of the laser beam, 21 is the optical path length calculation circuit,
22 is a spot diameter calculation circuit, 23a and 23b are addition circuits, 24 is an X-axis motor drive circuit, and 25 is a Y-axis motor drive circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] 1 The laser beam transmitted from the laser oscillator is focused by a condensing device installed in the processing head, and is irradiated onto the workpiece placed on the processing table,
In a laser processing machine that performs processing by moving the processing head, the processing is performed according to the spot diameter of the laser beam on the workpiece, which changes with the change in the optical path length from the laser oscillator to the light condensing device. A laser processing machine characterized by being provided with an offset amount control device that changes the offset amount of a head.