JP2021122837A - Method for controlling laser cutting robot, robot system, and laser cutting system - Google Patents

Abstract

To reduce defective cutting while suppressing tact time.SOLUTION: In control of a laser cutting robot 21 for cutting a workpiece W by irradiation with a laser beam L, during execution of copy control for controlling a piezo actuator and a uniaxial actuator 17 so as to keep a distance between a focal point of a condenser lens and the workpiece W constant, and the piezo actuator and the uniaxial actuator 17 are controlled so that a ratio of a moving amount of the condenser lens by driving of the piezo actuator in the moving amount in the optical axis direction of the condenser lens is increased, and a ratio of the moving amount of the condenser lens by driving of the uniaxial actuator 17 is decreased, as a horizontal component HL of a distance between a base part 9 and a tip of a robot arm 11 is longer.SELECTED DRAWING: Figure 1

Description

The present invention relates to a control method, a robot system, and a laser cutting system for a laser cutting robot that cuts a workpiece by irradiating a laser beam.

Patent Document 1 discloses, as a laser cutting system that cuts a work by irradiating a laser beam, a copying control that moves a cutting torch so as to keep a constant distance between the focal point of a condenser lens and the work. ing.

Japanese Unexamined Patent Publication No. 2-46992

By the way, in order to cut a work by irradiating a laser beam, a robot arm having a base portion and at least one joint portion and having a base end fixed to the base portion, and a laser beam emitted by a laser oscillator are used. It is provided with a processing head having a condensing lens that collects light at an irradiation position, and a head drive mechanism that is fixed to the tip of the robot arm to support the processing head and move the processing head in the optical axis direction. It is conceivable to use a laser cutting robot. In such a laser cutting robot, when the distance between the base portion and the tip of the robot arm or the horizontal component of the distance becomes long, the execution of copying control that keeps the distance between the focal point of the condenser lens and the work is constant. During this, the movement of the processing head causes a large vibration at the tip of the robot arm, which causes cutting defects such as dross generation.

Further, if the moving speed of the machining head is significantly reduced in order to reduce cutting defects caused by vibration of the tip of the robot arm, the tact time becomes long.

The present invention has been made in view of this point, and an object of the present invention is to reduce cutting defects while suppressing takt time.

The present invention targets the control of a laser cutting robot that cuts a workpiece by irradiating a laser beam, and has taken the following solutions.

That is, in the first to fourth inventions, the laser cutting robot has a base portion, at least one joint portion, and is emitted by a robot arm having a base end fixed to the base portion and a laser oscillator. A condensing lens that collects laser light, a processing head that has a lens drive mechanism that moves the condensing lens in the optical axis direction, and a processing head that is fixed to the tip of the robot arm to support the processing head and the processing. It has a head drive mechanism that moves the head in the optical axis direction, and controls the lens drive mechanism and the head drive mechanism so as to keep the distance between the focal point of the condenser lens and the work constant. During execution of control, the longer the distance between the base portion and the tip of the robot arm, or the horizontal component of the distance, the more the focusing is performed by driving the lens driving mechanism in the amount of movement of the focusing lens in the optical axis direction. It is characterized in that the lens driving mechanism and the head driving mechanism are controlled so that the ratio of the moving amount of the lens becomes high and the ratio of the moving amount of the condensing lens due to the driving of the head driving mechanism becomes low.

As a result, when the distance between the base portion and the tip of the robot arm or the horizontal component of the distance becomes long, the amount of movement of the entire machining head due to the drive of the head drive mechanism is reduced, and only a part of the machining head is largely moved. , The vibration of the tip of the robot arm can be suppressed without significantly reducing the moving speed of the condenser lens. Therefore, it is possible to reduce cutting defects caused by vibration of the tip of the robot arm while suppressing the tact time.

Further, in the second invention, the lens driving mechanism moves the condensing lens in the optical axis direction at the first average speed, and the head driving mechanism moves the processing head higher than the first average speed. It is characterized in that it is moved in the optical axis direction at the second average speed.

As a result, when the distance between the base and the tip of the robot arm, or the horizontal component of the distance, becomes shorter, the amount of movement of the condenser lens driven by the head drive mechanism, that is, the second average speed higher than the first average speed. Since the amount of movement of the robot increases, the tact time can be shortened.

According to the present invention, it is possible to suppress cutting defects caused by vibration of the tip of the robot arm while suppressing takt time.

It is the schematic which shows the structure of the laser cutting system which concerns on embodiment of this invention. It is a perspective view of a piezo actuator and a condenser lens. It is a flowchart of the control operation by a control device. The horizontal component of the distance between the base and the tip of the robot arm, the ratio of the movement amount of the condenser lens by the drive of the piezo actuator to the movement amount of the condenser lens, and the collection by the drive of the uniaxial actuator in the movement amount of the condenser lens. It is a graph which shows the relationship with the ratio of the moving amount of an optical lens. It is a schematic diagram which shows the state around the tip of a processing head before and after moving a condenser lens by driving a piezo actuator, (a) shows the state before moving, and (b) shows the state after moving. It is a schematic diagram which shows the state around the tip of a machining head before and after moving a machining head by driving a uniaxial actuator, (a) shows the state before move, and (b) shows the state after move.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description of preferred embodiments is merely exemplary and is not intended to limit the present invention, its applications or its uses.

As shown in FIG. 1, the laser cutting system 1 according to the embodiment of the present invention includes a laser oscillator 3, an optical fiber 5, and a robot system 7.

The laser oscillator 3 emits the laser beam L by oscillation.

The optical fiber 5 guides the laser beam L emitted by the laser oscillator 3 to the processing head 13 (described later) of the robot system 7.

The robot system 7 includes a base portion 9, a 6-axis articulated robot arm 11, a processing head 13, a capacitance type sensor electrode 15, a uniaxial actuator 17 as a head drive mechanism, and a control device 19. It has. The base portion 9, the robot arm 11, the processing head 13, the sensor electrode 15, and the uniaxial actuator 17 constitute the laser cutting robot 21.

The base end of the robot arm 11 is connected to the base portion 9, and the machining head 13 is attached to the tip of the robot arm 11 via a uniaxial actuator 17.

The processing head 13 irradiates the work W with the laser light L emitted by the laser oscillator 3 and guided to the processing head 13 by the optical fiber 5. The processing head 13 includes a substantially cylindrical case 13a extending in the vertical direction, and the case 13a constitutes the outer surface of the processing head 13.

Inside the case 13a, a piezo actuator 13b as a cylindrical lens driving mechanism shown in FIG. 2 is housed in a state in which the axial direction thereof is along the longitudinal direction (vertical direction) of the case 13a. The lower end of the piezo actuator 13b is fixed to the case 13a. The piezo actuator 13b expands and contracts in the axial direction at a predetermined expansion and contraction speed according to the input voltage. The outer peripheral portion of the condenser lens 13c is fixed to the upper end side surface of the piezo actuator 13b. The condenser lens 13c collects the laser light L emitted by the laser oscillator 3 and guided to the processing head 13 by the optical fiber 5. The piezo actuator 13b moves the condenser lens 13c in the optical axis direction (vertical direction) at a predetermined first average speed V1 by an expansion / contraction operation according to an input voltage.

Further, at the end of the processing head 13 on the nozzle side, a sensor electrode 15 for obtaining a capacitance value according to the distance from the work W in the optical axis direction as a measured value is provided.

The uniaxial actuator 17 is fixed to the tip of the robot arm 11 to support the machining head 13, and the machining head 13 is moved in the optical axis direction of the condenser lens 13c at a second average speed V2 higher than the first average speed V1. Move. The uniaxial actuator 17 is composed of a slider component 17a to which the machining head 13 is fixed and a main body device 17b for raising and lowering the slider component 17a. The main body device 17b includes a screw shaft 17c screwed into a screw hole formed through the slider component 17a, and a motor (not shown) for rotating the screw shaft 17c.

The control device 19 controls the piezo actuator 13b and the uniaxial actuator 17 so as to keep the distance between the focal point F (see FIG. 5) of the condenser lens 13c and the work W constant based on the measured values of the sensor electrode 15. Take control. The control device 19 controls the relative position of the condenser lens 13c with respect to the sensor electrode 15 by controlling the input voltage of the piezo actuator 13b. The control device 19 can recognize the relative position of the condenser lens 13c with respect to the sensor electrode 15, that is, the position of the condenser lens 13c on the processing head 13. The function of the control device 19 is realized by, for example, a CPU (Central Processing Unit).

Here, with reference to FIG. 3, the details of the operation during the execution of the copy control by the control device 19 will be described.

First, in (S101), the control device 19 acquires the relationship data showing the relationship between the distance between the sensor electrode 15 and the work W in the optical axis direction and the capacitance value measured by the sensor electrode 15.

Next, in (S102), the control device 19 acquires the capacitance value measured by the sensor electrode 15. The capacitance value measured by the sensor electrode 15 corresponds to the distance between the sensor electrode 15 and the work W in the optical axis direction and the distance between the processing head 13 and the work W in the optical axis direction.

Then, in (S103), the control device 19 determines the optical axis direction of the current sensor electrode 15 and the work W based on the relational data acquired in (S101) and the capacitance value acquired in (S102). Calculate the distance.

Next, in (S104), the control device 19 sets the current position of the focal point F of the condenser lens 13c based on the distance calculated in (S103) and the position of the condenser lens 13c in the current processing head 13. Calculate the difference from the target focal position.

Next, in (S105), the control device 19 calculates the required movement amount so that the focal point F of the condenser lens 13c is located at the target focal position according to the difference calculated in (S104).

Next, in (S106), the control device 19 acquires the horizontal component HL of the distance between the base portion 9 and the tip of the robot arm 11. Then, based on the horizontal component HL, the ratio P1 of the movement amount by driving the piezo actuator 13b to the movement amount of the condenser lens 13c in the optical axis direction and one axis in the movement amount of the condenser lens 13c in the optical axis direction. The ratio P2 of the amount of movement due to the drive of the actuator 17 is determined. Specifically, as shown in FIG. 4, when the horizontal component HL is less than 600 mm, both the ratios P1 and P2 are set to 50%. When the horizontal component HL is 600 to 1600 mm, the proportions P1 and P2 are determined so that the longer the horizontal component HL, the higher the proportion P1 and the lower the proportion P2. When the horizontal component HL exceeds 1600 mm, the ratio P1 is set to 100% and the ratio P2 is set to 0%.

Then, in (S107), the control device 19 moves the condenser lens 13c at the first average speed V1 by the movement amount of the ratio P1 of the required movement amount calculated in (S105) determined in (S106). To drive the piezo actuator 13b. Specifically, the piezo actuator 13b is expanded and contracted by the movement amount of the ratio P1 of the required movement amount determined in (S106). In FIG. 5, M1 indicates the amount of movement of the condenser lens 13c, and SH1 indicates the amount of movement of the focal point F. Further, the uniaxial actuator 17 is driven so as to move the machining head 13 at the second average speed V2 by the movement amount of the ratio P2 determined in (S106) of the required movement amount. In FIG. 6, M2 indicates the amount of movement of the processing head 13 incorporating the condenser lens 13c, and SH2 indicates the amount of movement of the focal point F.

For example, when the horizontal component HL of the distance between the base portion 9 and the tip of the robot arm 11 is 800 mm, in (S106), the ratio of the movement amount by the drive of the piezo actuator 13b to the movement amount of the condenser lens 13c. P1 is determined to be 60%, and P2, which is the ratio of the amount of movement by driving the uniaxial actuator 17 to the amount of movement of the condenser lens 13c, is determined to be 40%. Then, in (S107), the piezo actuator 13b is driven by the control of the control device 19 so as to move the condenser lens 13c by a movement amount of 60% of the required movement amount. Further, the uniaxial actuator 17 is driven by the control of the control device 19 so that the machining head 13 is moved by a movement amount of 40% of the required movement amount.

Further, when the horizontal component HL of the distance between the base portion 9 and the tip of the robot arm 11 is 1200 mm, in (S106), the ratio of the movement amount by driving the piezo actuator 13b to the movement amount of the condenser lens 13c. P1 is determined to be 80%, and the ratio P2 of the amount of movement by driving the uniaxial actuator 17 to the amount of movement of the condenser lens 13c is determined to be 20%. Then, in (S107), the piezo actuator 13b is driven by the control of the control device 19 so as to move the condenser lens 13c by a movement amount of 80% of the required movement amount. Further, the uniaxial actuator 17 is driven by the control of the control device 19 so that the machining head 13 is moved by a movement amount of 20% of the required movement amount.

The control device 19 repeats the above operations (S101) to (S107) with the target focal position set to a constant position, so that the distance between the focal point F and the work W of the condenser lens 13c is kept constant. Dripping. The control device 19 may perform the operation of (S101) only once at the beginning, and repeat only the operations of (S102) to (S107).

Therefore, according to the present embodiment, when the horizontal component HL of the distance between the base portion 9 and the tip of the robot arm 11 becomes long, the amount of movement of the entire machining head 13 driven by the uniaxial actuator 17 is reduced, and one of the machining heads 13 Since only the portion is largely moved, the vibration of the tip of the robot arm 11 can be suppressed without significantly reducing the moving speed of the condenser lens 13c. Therefore, it is possible to reduce cutting defects caused by vibration of the tip of the robot arm 11 while suppressing the tact time.

Further, when the horizontal component HL of the distance between the base portion 9 and the tip of the robot arm 11 becomes short, the amount of movement of the condensing lens 13c driven by the uniaxial actuator 17, that is, the second average speed V2 higher than the first average speed V1. Since the amount of movement in is increased, the tact time can be shortened.

In the present embodiment, the condenser lens 13c is moved by the piezo actuator 13b in the optical axis direction, but it may be moved by a lens driving mechanism other than the piezo actuator 13b.

Further, in the present embodiment, the processing head 13 is moved by the uniaxial actuator 17 in the optical axis direction of the condenser lens 13c, but it may be moved by a head drive mechanism other than the uniaxial actuator 17.

Further, in the present embodiment, in (S106), as the horizontal component HL of the distance between the base portion 9 and the tip of the robot arm 11 becomes longer, the ratio P1 becomes higher and the ratio P2 becomes lower. P2 was decided. However, the proportions P1 and P2 may be determined so that the proportion P1 increases and the proportion P2 decreases as the distance itself between the base portion 9 and the tip of the robot arm 11 increases. Further, the proportions P1 and P2 may be determined so that the proportion P1 increases and the proportion P2 decreases as the extension rate of the robot arm 11 with respect to a predetermined length increases.

The control method, robot system, and laser cutting system of the laser cutting robot of the present invention can suppress cutting defects caused by vibration of the tip of the robot arm while suppressing tact time, and cut the work by irradiation with laser light. It is useful as a control method for a laser cutting robot, a robot system, and a laser cutting system.

1 Laser cutting system 3 Laser oscillator 7 Robot system 9 Base 11 Robot arm 13 Machining head 13b Piezo actuator (lens drive mechanism)
13c Condensing lens 17 Uniaxial actuator (head drive mechanism)
19 Control device 21 Laser cutting robot F Focus L Laser beam W Work V1 First average speed V2 Second average speed P1, P2 Ratio

Claims (4)

It is a control method of a laser cutting robot that cuts a workpiece by irradiating a laser beam.
The laser cutting robot has a base portion and
A robot arm having at least one joint and having a base end fixed to the base.
A condensing lens that condenses the laser light emitted by the laser oscillator, and a processing head that has a lens drive mechanism that moves the condensing lens in the optical axis direction.
It has a head drive mechanism that is fixed to the tip of the robot arm, supports the processing head, and moves the processing head in the optical axis direction.
During execution of copying control that controls the lens drive mechanism and the head drive mechanism so as to keep the distance between the focal point of the condenser lens and the work constant, the distance between the base portion and the tip of the robot arm, or The longer the horizontal component of the distance, the higher the ratio of the amount of movement of the condenser lens by driving the lens drive mechanism to the amount of movement of the condenser lens in the optical axis direction, and the more the collection by driving the head drive mechanism. A control method for a laser cutting robot, characterized in that the lens drive mechanism and the head drive mechanism are controlled so that the ratio of the amount of movement of the optical lens is low. In the method for controlling a laser cutting robot according to claim 1,
The lens driving mechanism moves the condensing lens in the optical axis direction at the first average speed.
The head drive mechanism is a control method for a laser cutting robot, characterized in that the processing head is moved in the optical axis direction at a second average speed higher than the first average speed. A robot system that cuts a workpiece by irradiating a laser beam.
With the base part
A robot arm having at least one joint and having a base end fixed to the base.
A condensing lens that condenses the laser light emitted by the laser oscillator, and a processing head that has a lens drive mechanism that moves the condensing lens in the optical axis direction.
A laser cutting robot fixed to the tip of the robot arm, supporting the processing head, and having a head drive mechanism for moving the processing head in the optical axis direction, and a focal point of the condensing lens and the work. During execution of copying control for controlling the lens drive mechanism and the head drive mechanism so as to keep the distance constant, the longer the distance between the base portion and the tip of the robot arm, or the horizontal component of the distance, the more the said. The ratio of the amount of movement of the condensing lens driven by the lens driving mechanism to the amount of movement of the condensing lens in the optical axis direction is high, and the ratio of the amount of movement of the condensing lens driven by the head driving mechanism is low. The robot system is provided with a control device for controlling the lens drive mechanism and the head drive mechanism. The robot system according to claim 3 and
A laser cutting system including the laser oscillator.

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