JP2002239868A - Machine tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically set laser output power to the optimum value in accordance with cutting conditions of a workpiece to realize automatic and unmanned cutting work. SOLUTION: When the cutting conditions of the workpiece W are inputted in a controller 9 from a numeric input part 10, the controller 9 controls a machine tool body 1 in accordance with the inputted cutting conditions and calculates output power of laser beam outputted from a laser oscillator 8 based on the cutting conditions. The laser oscillator 8 is operated in synchronization with the control operation of the machine tool body 1, and laser beam is irradiated for chips generated from the workpiece W during cutting work to cut the chips to a predetermined length.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a machine tool having a function of cutting chips generated during cutting by a laser beam.

[0002]

2. Description of the Related Art Chips generated when performing boring or boring of metal cutting, if they are continuously generated, cling to a cutting tool, which hinders normal cutting work. For this reason, conventionally, a chip shape has been devised so as to change the flowing direction of chips running on the rake face of a chip breaker provided at the tip of a cutting tool, and cutting is performed by bending the chips with this force.

However, when the cutting depth is shallow and the generated chips are thin and thin, as in finishing, etc., the chips are not cut but are spirally discharged and a certain amount of chips are discharged to the cutting tool. Whenever they got entangled, the cutting process had to be interrupted each time to remove the spiral chips, resulting in poor work efficiency.

For this reason, various techniques for automatically cutting helical chips have been proposed. For example, see "Laser Research" Vol. 9, P582-591 discloses a technique for cutting a chip by converging and irradiating a chip with a laser beam.

[0005]

The optimum laser output power for cutting chips depends on the material of the work,
It differs for each cutting condition, such as the peripheral speed during cutting, the cutting depth of the cutting tool, and the feed pitch.

However, the output power of a laser beam output from a conventional laser oscillator is often set based on many years of experience of an operator, and requires skill.

Therefore, after setting the work on the cutting machine, the operator must perform the cutting work while adjusting the laser output power in accordance with the cutting conditions of the work. Had led to a decline.

Further, since the cutting operation has to be performed while checking the laser output power, it has been difficult to realize unmanned operation and automation of the operation.

Accordingly, an object of the present invention is to automatically set a laser output power to an optimum value according to a cutting condition of a work, thereby improving work efficiency, and making unmanned and automatic cutting work. An object of the present invention is to provide a machine tool capable of realizing the above.

[0010]

In order to achieve the above object, a machine tool according to the present invention comprises a machine tool body for cutting a work, and a laser beam for irradiating chips generated during the cutting process to cut the chips. A laser oscillator to generate,
A control unit for controlling the machine tool main body in accordance with the input cutting conditions and calculating a laser output power to the laser oscillator based on the cutting conditions, wherein the control unit synchronizes with the control operation of the machine tool main body. Operating the laser oscillator.

According to such a configuration, when cutting conditions are input to the control unit, the control unit controls the machine tool body in accordance with the input cutting conditions, and outputs an output from the laser oscillator based on the cutting conditions. The output power of the laser beam to be calculated is calculated. Then, a laser beam having a predetermined output power is output from the laser oscillator in synchronization with the control operation of the machine tool main body, and the laser beam is irradiated on the chips generated during cutting to cut.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Here, FIG. 1 is a plan view showing the entire configuration of the machine tool, and FIG. 2 is a sectional view taken along line II-II of FIG.

A machine tool main body 1 shown in FIG. 1 is an automatic lathe. A bar-shaped work W is gripped by a collet chuck 3 provided on a headstock 2, and a cutting tool 4 is fixedly mounted on the work W in a direction perpendicular to the axis. A mounting base 5 is provided.

As shown in FIG. 2, the cutting tool 4 has a cutting tip 4a fixed to the tip. Note that the reference sign Wa is a chip shaved from the workpiece W. Chips Wa generated at the time of finishing are thin and thin, and the cross section thereof has a substantially sector shape (see FIG. 4).

In the vicinity of the start of the cutting of the chips Wa cut from the workpiece W of the cutting tool 4, the emitting end of the laser optical system 6 is set upright or inclined at a certain angle (for example, 45 degrees). The laser optical system 6 is fixed to the mount 5 via a bracket (not shown).

The laser optical system 6 is connected to a laser oscillator 8 via an optical fiber 7, and a laser such as a YAG laser output from the laser oscillator 8 is condensed by the laser optical system 6 via the optical fiber 7. The laser beam L is irradiated onto the chip Wa.

As shown in FIG. 1, the operations of the machine tool main body 1 and the laser oscillator 8 are centrally managed by a control device 9. The controller 9 includes a numerical input unit 10 such as a keyboard.
Is connected, and a numerical input unit 1
From 0, cutting conditions are input to the control device 9.

The controller 9 controls the output power P of the laser output from the machine tool body 1 and the laser oscillator 8 according to the input cutting conditions. This control is specifically processed according to a control routine shown in FIG.

In this routine, first, in step S1
Then, the cutting conditions input from the numerical value input unit 10 are read. The cutting conditions are, for example, the material of the work W, the cutting depth (t) of the cutting tool 4, the feed pitch (f), the peripheral speed (v) of the work W at the time of cutting. Is the pulse width (Tp) of the laser beam L output from the laser oscillator 8. This pulse width (Tp)
May be a fixed value set in advance. In this case, the pulse width (Tp) does not need to be input from the numerical value input unit 10.

When data relating to the material of the work W is input from the numerical value input unit 10, specific heat (C), density (d), heat of fusion (λ), and melting point (T
1) is automatically set.

Next, the process proceeds to step S2, where the output power P of the laser output from the laser oscillator 8 is calculated based on the input cutting conditions.

Although the procedure for calculating the laser output power P is not particularly limited, it can be determined by the following formula, for example.

First, the cutting depth (t) and the feed pitch (f)
From the following equation (1), the cutting sectional area (S
2) Ask for.

S2 = k1 · t · f (1) Here, k1 is a constant set for each material. As shown in FIG. 6, the cutting sectional area of the chip Wa obtained by the calculation shown on the horizontal axis and the measured value of the sectional area shown on the vertical axis are 1: 1.
, And in fact, for a certain percentage (k
1) More are cut out.

Thereafter, the outflow velocity (v2) of the chip Wa is determined based on the cutting depth (t), the feed pitch (f), the peripheral velocity (v), and the cutting sectional area S2.

Here, since the cut-out amount of the chip Wa is f.t.v = S2.v2 (2), v2 = f.t.v / S2 (3)

Next, as shown in FIG. 4, the chip Wa moving between the pulse width (Tp) from the chip outflow velocity (v2), the pulse width (Tp) of the laser oscillator 8, and the cutting sectional area (S2). Is obtained from the following equation.

A = v2 · Tp · S2 (4) On the other hand, as shown in FIG. 5, when the chip Wa passes through the spot of the laser beam L, the chip is irradiated with the laser beam during the pulse width (Tp). The region L2 that moves from the region where the laser beam L first has the spot diameter (D) to the region L2 that moves out of the region during the pulse width (Tp).
An area L2 is obtained by subtracting 1.

Here, the volume corresponding to L1 is substantially equal to the volume (A) obtained by the above equation (4). Also,
First, the volume (B) of the area that falls within the spot diameter (D) of the laser beam L can be obtained from the following equation.

B = D · S 2 (5) Accordingly, the volume (C) of the area L 2 irradiated with the laser beam during the pulse width (Tp) can be obtained from the following equation.

C = BA = D · S 2 −v 2 · Tp · S 2 = (D−v 2 · Tp) · S 2 (6) The cutting of the chip Wa is performed at the highest temperature, that is, the pulse width (Tp). During the region L2 irradiated with the laser beam. Therefore, the volume (C) of the region L2
It is necessary to irradiate as much energy as possible to melt the chips Wa having a mass corresponding to. This mass (m) is obtained from the above volume (C) and density (d) by the following equation.

M = C · d = (D−v 2 · Tp) · S 2 · d (7) Next, the mass (m), specific heat (C), heat of fusion (λ), and melting point (T1) of the chip Wa , The required energy E for melting the chip Wa is calculated from the following equation.

E = m · (C · (T1−T2) + λ) (8) Here, T2 is room temperature.

The required energy E and the laser beam L
Is calculated based on the pulse width Tp of the laser output power P.

K2 · P · Tp ≧ E (9) Here, k2 is a constant determined by the output loss of the laser beam by the optical system lens and the absorptivity of the laser beam L to the chip Wa.

Then, the process proceeds to step 3, where the cutting conditions obtained in step 1 are stored, and a drive signal corresponding to the laser output power P obtained in step 2 is output to the laser oscillator 8, and the routine ends.

Thereafter, when the operator starts the machine tool, the machine tool body 1 rotates the work W according to the set cutting conditions, and the cutting tool 4 starts cutting. In synchronization with this, a laser having an optimum power corresponding to the material of the work W is output with a predetermined pulse width from the laser oscillator 8 to the laser optical system 6 via the optical fiber 7 and focused by the laser optical system 6. Laser beam L
Is applied to the chip Wa, and the chip Wa is blown at a predetermined length.

In this case, in order to avoid damage due to laser irradiation, a hole may be formed in the cutting tip 4a at a position where the laser beam is irradiated, or a coating having a high laser reflectance may be applied to the surface.

According to experiments, for example, when the laser beam is a YAG laser, the laser output power P is preferably about 400 W when the work W is copper (Cu).
When the work W is iron (Fe), stainless steel (SUS), or aluminum (Al), about 100 W is preferable.
At this time, the pulse width Tp of the laser beam L is
0.5 to 1.5 ms is preferred.

As described above, according to the present embodiment, the laser output power P is set according to the cutting conditions input when starting the cutting, and in synchronization with the start of cutting by the machine tool body 1, Since the output of the laser beam L is started, the chips Wa cut out from the work W are automatically melted at a predetermined length by the laser beam L having the optimum output power, so that the working efficiency is improved. In addition, unmanned and automatic cutting operations can be realized.

[0041]

As described above, according to the present invention,
The laser output power can be automatically set to the optimum value according to the cutting conditions of the work, and the laser oscillator is operated in synchronization with the control operation of the machine tool main body, improving work efficiency. Not only can it be achieved, but also unmanned and automatic cutting can be realized.

[Brief description of the drawings]

FIG. 1 is a plan view showing the entire configuration of a machine tool.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a flowchart showing a control routine.

FIG. 4 is a perspective view of a chip portion melted by a laser beam.

FIG. 5 is an explanatory diagram showing a relationship between a laser beam spot diameter and a chip moving speed.

FIG. 6 is a table showing a relationship between a calculated cutting cross-sectional area of a chip and a measured cross-sectional area of the chip.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Machine tool main body 1 8 Laser oscillator 9 Control device (control part) L Laser beam P Laser output power W Work Wa Chip

Claims (1)

[Claims] 1. A machine tool main body for cutting a work, a laser oscillator for irradiating chips generated during the cutting process to generate a laser beam for cutting the chips, and a machine tool main body according to input cutting conditions. A control unit for performing a control operation and calculating a laser output power for the laser oscillator based on the cutting condition, wherein the control unit operates the laser oscillator in synchronization with a control operation of the machine tool main body. And machine tools.