JPH04367385A - Laser beam machine - Google Patents

Abstract

PURPOSE:To detect not only a position but also an abnormal state by a simple constitution. CONSTITUTION:By a contact type sensor 6, a distance between the working surface 3a of an object 3 to be worked and a working head 1 is detected as a voltage value. A control circuit 7 adjusts the distance between the working head 1 and the object 3 to be worked so as to become a correct working position, based on the detected voltage from the sensor 6. Also, the control circuit 7 drives its variation quantity and variation rate, based on the detected voltage from the sensor 6, discriminates between a variation caused by waviness, etc., of the working surface 3a of the object 3 to be worked, and a variation caused by a fact foreign matter, etc., are jammed, and decides whether it is in an abnormal state or not.

Description

[Detailed description of the invention]

[Purpose of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing machine that irradiates a relatively moving workpiece with laser light in a condensed state using an optical system.

0002

[Prior Art] A laser processing machine guides a laser beam output from a laser oscillator to a laser processing head, focuses the light using a condensing optical system such as a lens installed inside the processing head, and creates a focal point with high energy density. The workpiece is processed by irradiating the workpiece with focused laser light in the vicinity.

In such laser processing, especially when cutting materials, it is necessary to accurately control the relative positional relationship between the focused position of the laser beam and the processed surface of the workpiece. This is an important point that determines cutting ability.

[0004] In this case, for example, the processing operation for a workpiece is performed while moving the processing head in a direction perpendicular to the optical axis direction of the laser beam. If the workpiece is deformed, move the workpiece or processing head to follow this so that the distance in the optical axis direction between the laser beam focus position and the processing surface of the workpiece does not change greatly. It is necessary to perform control so that the relative positional relationship between the two falls within a predetermined range.

Means for measuring the above-mentioned relative positional relationship include, for example, a non-contact type sensor that detects capacitance that changes depending on the distance between the workpiece and the processing head; There is a contact-type sensor that is in contact with the processing surface of a workpiece and obtains an output from a differential transformer according to the distance therebetween.

[0006] In the above case, the non-contact type sensor has multiple functions in terms of sensing distance and detecting collisions with foreign objects, but is therefore expensive, whereas the contact type sensor Although it has a single function of sensing, it is inexpensive. Therefore, in general, one of these types of sensors is used as required.

[0007] As a result, no matter which sensor is used, even if the processed surface of the workpiece has undulations, the distance can be detected by following the undulations, and the focus position of the laser beam and the processed surface can be determined. The cutting process can be performed reliably by controlling the movement of the distance between the two.

[0008]

However, when a contact type sensor is used among the above-mentioned sensors, the following problems may occur. In other words, for example, if foreign matter is attached to the machined surface of the workpiece, or if material left after cutting is caught between the machined surface and the sensor head, the sensor head and the machined surface may The relative positional relationship between the two may be disturbed, or the sensor head may collide with a foreign object, which may impede the movement of the processing head itself.

[0009] In such a case, the detection output from the sensor becomes abnormal and normal position detection is no longer possible.
Cutting with laser light becomes difficult. Therefore, it is necessary to stop the equipment and eliminate such a problem, but when using a contact type sensor as mentioned above, it is necessary to simply control the relative positional relationship, so this problem is impossible. There was a problem in which abnormal conditions such as these could not be detected.

The present invention has been made in view of the above circumstances, and its purpose is to control the position between the processing surface of the workpiece and the processing head by detecting the position between the processing surface of the workpiece and the processing head using a contact type sensor. To provide a laser processing machine which is capable of detecting not only a position detection function but also an abnormal state even when performing laser processing. [Structure of the invention]

[0011]

[Means for Solving the Problems] The present invention is directed to a laser processing machine that irradiates a relatively moving workpiece with a laser beam in a condensed state by an optical system. A sensor that detects the distance between the machined surface of the workpiece and the proper processing position by the laser beam in a contact state, and controls the movement of the machined surface of the workpiece to the proper processing area based on the detection output of this sensor. The present invention is characterized in that it also includes a control means for determining an abnormal state based on the rate of change of the detected output and the maximum value of the amount of change.

0012

[Operation] According to the laser processing machine of the present invention, processing is performed by irradiating a relatively moving workpiece with laser light in a condensed state, and at this time, the control means is based on the detection output from the sensor. The machine moves the machining surface of the workpiece to the appropriate machining position while performing appropriate machining operations.

[0013] When performing a machining operation in this way, when the detected output of the sensor suddenly changes or the amount of change becomes large, the control means, based on the rate and amount of change, For example, it is determined whether or not an abnormal operation is occurring in the following manner.

That is, first, the magnitude of the amount of change indicates the degree of displacement with the machined surface, and if the machined surface of the workpiece has gentle irregularities such as waviness and the amount of change gradually increases. , it will be outside the appropriate range for normal laser processing, making processing difficult. Therefore, the relative distance between the workpiece and the processing head is corrected based on the amount of change and controlled to fall within the appropriate range.

However, unlike the above, when a foreign object is caught between the machining surface and the machining head or there is a collision with a foreign object, the detection output of the sensor increases rapidly, and only the amount of change In addition, its differential value, that is, the rate of change, also increases. Therefore, the control means distinguishes such a state of displacement accompanied by a large rate of change from the above-mentioned case and determines it as an abnormal state, and outputs a display to that effect or outputs a signal to stop the apparatus.

[0016] As a result, the state of laser processing by the processing head is judged based on both the amount of change and the rate of change, so it is possible to detect abnormalities such as displacement due to waviness of the processing surface of the workpiece and foreign objects, etc. This allows for more accurate laser processing.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic configuration of a processing head 1, in which a laser beam guided from a laser oscillator (not shown) through an optical system is focused by a condensing lens 2, and then passes through a tip portion 1a. The beam is outputted from the processing table and irradiated onto the processing surface 3a of the workpiece 3 placed on the processing table.

The annular sensor head 4 is located so as to surround the tip portion 1a of the processing head 1, and is arranged to surround the tip portion 1a of the processing head 1.
It is disposed so as to be movable in the vertical direction along with the vertical movement thereof while in contact with the processing surface 3a. The amount of mechanical change due to the vertical movement of the sensor head 4 is transmitted to a differential transformer 5 provided on the side of the processing head 1, and the differential transformer 5 generates an electric current indicating the amount of change. It is designed to be output as a standard detection signal. The sensor head 4 and the differential transformer 5 constitute a sensor 6. In other words, the sensor 6 is connected to the processing head 1 and the workpiece 3.
It is detecting the relative distance between

002
[0] The control circuit 7, which is a control means, is configured to receive a detection signal from the differential transformer 5, and as described below, controls the processing head 1 in the vertical direction via the drive mechanism 8 in accordance with the detection signal. In addition to controlling the position, it is also determined whether or not the processing state of the workpiece 3 by the laser beam is abnormal. Next, we will explain the operation of this embodiment in Figure 2.
This will be explained with reference to FIG.

The control circuit 7 moves the processing table in the horizontal direction according to the processing process of the workpiece 3, and controls the processing head 1.
The processing surface 3a is processed by laser light irradiated from the laser beam. At this time, the processing head 1 and the processing surface 3a of the workpiece 3
The distance between the two is detected by a sensor 6, and the processing head 1 is controlled to move in the vertical direction so that the processing surface 3a is always at an appropriate position.

In this case, the detection signal from the sensor 6 is set to have a value of, for example, 5 (V) when the processed surface 3a is in the proper position for laser processing, and the detected signal is set to have a value of 5 (V), for example, when the processed surface 3a is in the proper position for laser processing. If the distance between the machining head 1 and the machining head 1 changes due to the presence of foreign matter or the adhesion of foreign matter, the distance will change in direct proportion within the range of 0 (V) to 10 (V), as shown in Figure 2. It has become.

As a criterion for determining the laser processing state in the control circuit 7, the maximum value of the amount of change is, for example, E(V).
The rate of change is set to F (V/sec).

Now, when performing laser processing as described above, when the condition of the processed surface 3a of the workpiece 3 is normal, that is, when the processed surface 3a is not undulated or has any foreign matter attached to it. , the value of the detection signal from the sensor 6 is always 5 (V), as shown in FIG. 3(a).
Therefore, laser processing is performed without controlling the movement of the processing head 1 in the vertical direction.

However, if there are foreign substances attached to the machined surface 3a of the workpiece 3, such as slag generated during drilling, cutting scum during cutting, or leftover materials left behind, As shown in FIG. 3(b), the detection output by the sensor 6 is C(V), which exceeds E(V), and the rate of change is A(V/sec), which exceeds F(V/sec). ). As a result, the control means 7 controls the processing surface 3 of the workpiece 3.
It determines whether the state of a is abnormal and outputs a signal indicating the occurrence of the abnormality. In this case, for example, the laser processing is stopped and a notification is issued to prevent the laser processing operation from proceeding in an abnormal state and causing a failure or accident.

Next, the detection signal from the sensor 6 is shown in FIG.
), it may show gradual changes. This is because, for example, the amount of change gradually increases or decreases as the laser processing progresses due to waviness or the like on the processed surface 3a of the workpiece 3. Even when the maximum value E (V) is exceeded, the rate of change is often about B (V/sec), which does not exceed the maximum value F (V/sec). Therefore, the control circuit 7 does not judge this as an abnormal state, but drives and controls the processing head 1 to an appropriate position via the drive circuit 8 to continue the laser processing operation.

[0027] Even if the above-mentioned foreign matter is caught,
As shown in Fig. 3(d), the amount of change is small, and the maximum value E
(V), the processing head 1 is moved to the proper position via the drive circuit 8 without being judged as abnormal even if the rate of change is A (V/sec). The drive is controlled to continue the laser processing operation.

According to this embodiment, the contact type sensor 6 detects the relative distance between the processing head 1 and the processing surface 3a of the workpiece 3, and determines the maximum value and rate of change of the detection signal. The machining surface 3a of the workpiece 3 based on the maximum value of
Since the abnormal state of the machined surface 3a is determined, the
When the rate of change is gradual due to undulations or the like, it is not judged as an abnormality, and an abnormality detection signal can be outputted in order to reliably detect an abnormal state due to a foreign object or the like and protect the device.

[0029]

As explained above, according to the laser processing machine of the present invention, the sensor detects the distance between the processing surface of the workpiece and the proper processing position by the laser beam in a contact state, and the control means As a result, abnormal conditions are determined based on the rate of change in the detection output and the maximum value of the amount of change.
With a simple configuration, it is possible to not only detect the position of the workpiece but also to detect abnormalities in the laser processing operation due to foreign objects or the like, which is an excellent effect.

[Brief explanation of the drawing]

FIG. 1 is a side view of a schematic configuration of essential parts showing an embodiment of the present invention.

[Figure 2] Diagram showing the correlation between sensor detection output and amount of change

[Figure 3] Diagram showing the time course of sensor detection output in various states of the machined surface of the workpiece

[Explanation of symbols]

1 is a processing head, 2 is a condensing lens, 3 is a workpiece, 3a
4 is a processing surface, 4 is a sensor head, 5 is a differential transformer, 6 is a sensor, 7 is a control circuit (control means), and 8 is a drive circuit.

Claims (1)

[Claims] 1. A laser processing machine configured to irradiate a workpiece that is relatively moved with laser light in a condensed state by an optical system, wherein a processing surface of the workpiece and an appropriate processing position by the laser light are determined. a sensor that detects the distance between the two in a contact state, and a sensor that controls the movement of the machining surface of the workpiece to an appropriate machining area based on the detection output of this sensor, and also determines the rate of change and the maximum value of the amount of change of the detection output. A laser processing machine comprising a control means for determining an abnormal state based on.