JP3860879B2 - Laser processing state detection method and laser processing system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to the technical field of laser processing, and particularly relates to a technique for managing a processing state of a portion to be processed by laser irradiation.
[0002]
[Prior art]
In the field of packaging materials, laser processing is used for processing resin films and the like. Specifically, in addition to cutting and punching the film, marking for recording characters on the film, melting a part of the multilayer film to form a kerf, and providing easy opening to the packaging bag Laser processing is used in so-called half-cutting.
[0003]
In laser processing, the quality and accuracy of processing vary depending on the state in which the workpiece is irradiated with the laser, specifically, the intensity of the laser, the degree of laser focusing (laser spot diameter at the irradiation point), and the like. Therefore, it is necessary to detect and manage the machining state in order to continuously perform good machining with high accuracy. Conventionally, evaluation of the processing state in this laser processing has been performed by two kinds of methods.
[0004]
The first method is a method of observing and evaluating the quality and accuracy of the processed state of the workpiece after actual processing. In the second method, a laser beam is focused on the workpiece, and a part of the laser beam is branched by a half mirror or the like in the optical path before the focusing means, and the intensity of the branched laser beam is received. Is a method of measuring and evaluating
[0005]
[Problems to be solved by the invention]
However, the first method is a posteriori, and it is inevitable that many defective products are manufactured before the measurement and evaluation results are reflected on the laser processing apparatus side to obtain a good processing state. In addition, since the processed part is evaluated for a certain number of samples of the workpiece, it is difficult to measure and evaluate all the numbers in real time in-line because of the relationship with the speed of the production line.
[0006]
On the other hand, in the second method, a part of the laser beam is branched and used for measurement purposes, so that laser output loss occurs. Further, since an optical element such as a half mirror for branching the laser beam is required in the optical path of the laser beam, the configuration of the optical system becomes complicated. Furthermore, if the branch output is reduced due to dirt on the mirror or the like, the measurement accuracy is reduced, and mirror maintenance is also required. Further, the measurement of the branched laser beam is only indirect, and does not directly detect the state of the laser actually irradiated on the workpiece. Therefore, for example, even if the lens that collects the laser beam on the workpiece is clouded or contaminated, and the laser irradiated to the workpiece is in an inappropriate state, It is not possible to detect defects.
[0007]
Therefore, by any of the above methods, the state of the laser light irradiated to the workpiece cannot be detected directly and in-line in real time.
[0008]
The present invention has been made in view of the above points, and in laser processing, a laser processing state capable of detecting and managing a laser processing state on a workpiece directly and in-line in real time. It is an object to provide a management method and an apparatus therefor.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 is a method of detecting a processing state in laser processing in which processing is performed on a workpiece by laser irradiation, wherein the workpiece has a resin film having a different laser absorption. The melt state of the resin film of each layer is detected by measuring the surface temperature of the workpiece at the laser irradiation position in a non-contact manner.
[0010]
According to the method configured as described above, since the measured temperature of the workpiece surface represents the machining state including the laser intensity, it is possible to directly detect the machining state of the part that is actually processed. Can do. In addition, processing can be performed without affecting the workpiece. In addition, various processing such as half-cutting of the resin film becomes possible.
[0011]
According to a second aspect of the present invention, in the method for detecting a machining state in laser processing in which a workpiece is processed by laser irradiation, the workpiece is a multilayer film including a resin film having at least one layer of laser absorption. The temperature of the surface of the workpiece at the laser irradiation position is measured in a non-contact manner to detect the molten state of the resin film of each layer.
[0012]
According to the method configured as described above, since the measured temperature of the workpiece surface represents the machining state including the laser intensity, it is possible to directly detect the machining state of the part that is actually processed. Can do. In addition, processing can be performed without affecting the workpiece. In addition, various processing such as half-cutting of the resin film becomes possible.
[0013]
According to a third aspect of the invention, in the laser machining state detecting method according to claim 2, wherein the laser is constituted by a carbon dioxide laser. Thereby, the laser processing of the resin film can be easily performed.
[0014]
According to a fourth aspect of the present invention, there is provided a laser processing apparatus that performs laser processing by laser irradiation on a resin film of a multi-layered film including resin films having different laser absorption properties, and the laser irradiation position at the laser irradiation position. A temperature detection device for detecting the temperature of the surface of the workpiece, and detecting the melting state of the resin film of each layer according to the output of the temperature detection device, and based on the detection result, the laser intensity in the laser processing device And a control device for controlling.
[0015]
According to the system configured as described above, since the measured temperature of the workpiece surface represents the machining state including the laser intensity, the machining state of the machining portion is directly detected, and laser machining is performed accordingly. The device can be appropriately controlled. In addition, processing can be performed without affecting the workpiece. In addition, various processing such as half-cutting of the resin film becomes possible.
[0016]
According to a fifth aspect of the present invention, in the laser processing system according to the fourth aspect, the intensity of the laser is controlled so that a predetermined processing depth or processing width can be obtained with respect to a predetermined resin film. And Thereby, various processes, such as a half cut of a resin film, can be performed reliably.
[0017]
According to a sixth aspect of the present invention, there is provided a laser processing apparatus that performs laser processing by laser irradiation on a resin film of a workpiece formed of a multilayer film including a resin film having a laser absorptivity in at least one layer. A temperature detection device that detects the temperature of the surface of the workpiece at the irradiation position, and detects the molten state of the resin film of each layer according to the output of the temperature detection device, and the laser processing device based on the detection result And a control device for controlling the intensity of the laser.
According to the system configured as described above, since the measured temperature of the workpiece surface represents the machining state including the laser intensity, the machining state of the machining portion is directly detected, and laser machining is performed accordingly. The device can be appropriately controlled. In addition, processing can be performed without affecting the workpiece. In addition, various processing such as half-cutting of the resin film becomes possible.
[0018]
A seventh aspect of the present invention is the laser processing system according to the sixth aspect , wherein the laser is constituted by a carbon dioxide gas laser. Thereby, the laser processing of the resin film can be easily performed.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention will be described below with reference to the drawings.
[0020]
First, the principle of laser processing state detection in the present invention will be described. In the present invention, the workpiece is processed by melting the workpiece surface by laser irradiation. When an object having absorption at the wavelength of the laser beam is irradiated with laser, the object is melted and evaporated by the energy of the laser. The heat generation (temperature) of the laser irradiated portion is almost proportional to the laser power to be irradiated. Therefore, the processing state of the workpiece surface that is the target of laser irradiation is detected by detecting the heat generation temperature of that portion.
[0021]
In the present invention, the temperature is measured by a non-contact method by using the radiant energy or electromagnetic property radiated from the object. Advantages of the non-contact method are as follows: (1) It is possible to measure a minute surface with an appropriate design of the optical system without affecting the object to be measured; (2) Easy to measure a moving object; 3) The response is quick.
[0022]
Any object emits energy of a certain wavelength if it is above absolute zero. The radiant energy has various wavelengths, and the radiant intensity varies depending on the temperature. Since the wavelength at which the radiation intensity is maximum varies depending on the temperature, the temperature of the object surface can be measured by detecting the peak wavelength. In the present invention, the temperature measuring device is not particularly limited as long as it is a non-contact type, but since the peak wavelength of radiant energy is in the infrared wavelength range from room temperature to 1000 ° C., an infrared camera is suitable.
[0023]
Regarding the type of laser for processing, the surface of the non-workpiece absorbs the laser as described above, and the processing is performed by heat generation and melting. The type of laser may be determined in consideration. For example, an excimer laser, a YAG laser, a carbon dioxide laser, a semiconductor laser, an argon laser, or the like can be used. In the embodiment described below, a resin film is used as the workpiece. Since the resin film has absorption near the wavelength of 10.6 μm, a carbon dioxide laser is used.
[0024]
In the following examples, a resin film is adopted as a workpiece, but it may be a single layer or a multilayer. In the case of a single layer resin film, examples of laser processing include cutting and punching marking. Moreover, in the case of the multilayer film which combined the resin film from which laser absorptivity differs, the half cut process (melting only one part layer) for providing easy-opening property to a packaging bag etc. is mentioned. Desirable for packaging materials with various properties by using a film that almost transmits carbon dioxide laser such as polyethylene and polypropylene, or a material that reflects almost carbon dioxide laser such as aluminum foil in combination with a film having high laser absorption. Laser processing is possible. In the following embodiments, description will be made by taking half-cut processing of a multilayer resin film as an example.
[0025]
FIG. 1 schematically shows the configuration of a laser processing apparatus and its line management apparatus according to an embodiment of the present invention. In FIG. 1, a resin film 10 that is a workpiece is supplied in a roll state and is conveyed in the direction of an arrow. On the surface of the resin film 10, laser light L emitted from a light source (not shown) is condensed through the objective lens 4 to form a minute laser spot.
[0026]
In this embodiment, the resin film 10 is a two-layer film having an ONy (stretched nylon) layer and an LLDPE (linear low density polyethylene) layer as shown in FIG. 2A, and oscillates from the ONy layer side. A carbon dioxide laser with a wavelength of 10.6 μm is focused and irradiated to form a laser spot with a spot diameter of 0.004 inches, and at the same time, the resin film 10 is conveyed in the direction of the arrow at a speed of 30 m / min. The ONy layer is melted by the energy of the irradiated laser beam, and the cut groove 11 is formed in the ONy layer.
[0027]
The line management apparatus shown in FIG. 1 has an infrared camera 2 to detect the temperature of a portion (laser spot portion) irradiated with laser light. This infrared camera 2 is arranged at a distance of 250 mm from the measurement point (that is, the laser spot) and measures with a measurement visual field φ10 mm.
[0028]
As described above, the melting of the ONy layer depends on the degree of temperature change (heat generation) due to laser irradiation. Therefore, if the irradiation laser intensity is insufficient, the ONy layer of the resin film 10 is not sufficiently melted, and the kerf is not sufficiently formed. Therefore, when a packaging bag is formed with this resin film, even if the user tries to tear the bag along the kerf when opening, the film is not cut correctly along the kerf. That is, the film may be cut off from the cut groove (called “guide removal”), and the easy opening of the packaging bag is not ensured. On the other hand, if the irradiation laser is too strong, not only the ONy layer of the resin film 10 but also the LLDPE layer below it is partially melted. Therefore, although opening becomes easy, the impact resistance as a packaging bag becomes weak conversely, and the content may leak. Therefore, it is necessary for the laser to have such an intensity that the ONy layer is sufficiently melted at the irradiated portion on the surface of the resin film 10 and that the LLDPE layer below is not melted.
[0029]
From the above points, the laser intensity applied to the resin film surface was changed, and the irradiation laser intensity, the temperature of the resin film surface detected by the infrared camera 2 and the molten state of the multilayer film were compared. As shown in FIG. 2A, laser light L is irradiated from the ONy layer side to the surface of the resin film 10 by the objective lens 4, and the intensity of the laser light L is changed between 2 watts (W) and 10 watts. It was.
[0030]
As shown in FIGS. 2B and 3A to 3C, when the irradiation laser output is 2 watts, the ONy layer is not sufficiently melted, and as a result, the grooves formed are formed into the ONy layer and the LLPDE. Does not reach the layer boundary. Accordingly, the easy-openability as a packaging bag is insufficient.
[0031]
When the laser output was between 4 watts and 8 watts, the ONy layer was sufficiently melted and a groove reaching the vicinity of the boundary with the LLDPE layer was formed. In the range of 2 watts to 8 watts, the width of the groove formed (processing width, see FIG. 3B) increases as the laser intensity increases, but melting to the LLDPE layer does not occur. Therefore, if it is in this range, easy-openability as a packaging bag will be good.
[0032]
On the other hand, when the laser intensity reaches 10 watts, the LLDPE layer melts. Therefore, problems arise in terms of strength and impact resistance as a packaging bag.
[0033]
FIG. 4A shows the relationship between the irradiated laser power and the processing width of the ONy layer, and FIG. 4B shows the relationship between the laser power and the processing depth (see FIG. 3C). As shown in FIG. 4A, in the ONy layer, as the laser power increases, the processing width increases approximately proportionally. Further, as shown in FIG. 4B, when the laser power is changed, the ONy layer melts to the boundary with the LLDPE layer in the vicinity of 4 watts. Thereafter, the processing depth remains constant up to about 8 watts, that is, the processing width increases without melting up to the LLDPE layer. When the laser power is further increased, the LLDPE layer starts to melt.
[0034]
Next, a packaging bag was manufactured from the multilayer film subjected to half-cut processing as described above, and an opening test and a drop impact test were performed. Specifically, the LLDPE film surface of the multilayer film subjected to half-cut processing as described above is opposed so that the formed kerf is located at the same position on the front and back of the pouch, and the peripheral edge is sealed to 125 mm. A packaging bag of × 250 mm was produced.
[0035]
As the opening test, 10 packaging bags were opened using the opening cuts formed, and the number of cuts that caused the guide to come off at that time was confirmed. In addition, as a drop impact test, the manufactured packaging bag was filled with 500 ml of water as the contents, and the mouth was heat sealed to produce a package. Then, 10 pieces of the packaging bodies were dropped 20 times perpendicularly to the concrete surface from a height of 120 cm, and the number of the packaging bodies to which the portions subjected to the half cut processing were torn by impact were counted. The results are shown in FIG.
[0036]
As can be seen from FIG. 5A, when the temperature measured by the infrared camera 2 was 2 watts, three of the ten bags were unguided in the opening test. As shown in FIG. 3A, this is presumably due to the fact that the ONy layer is not completely melted by laser irradiation of 2 watts. On the other hand, in the drop impact test, in the case of a laser power of 10 watts, two of the 10 bags were ruptured from the half-cut processed part due to the impact of the drop. As shown in FIG. 3C, this is presumed to be because the impact resistance of the bag was lowered because the laser power was too strong and the LLDPE layer was melted.
[0037]
From the above results, it can be seen that the temperature detected by the infrared camera 2 is good within the range of 90 degrees Celsius to 203 degrees Celsius. Therefore, while the half-processed resin film is performed on the laser processing apparatus shown in FIG. 1, the temperature of the processed part is detected by the infrared camera 2, and the line management apparatus 5 detects this when the detected temperature deviates from the above range. Then, a warning is issued or the line is automatically stopped.
[0038]
Next, with the laser processing apparatus shown in FIG. 1, the same resin film is subjected to half-cut processing by fixing the laser output to 5 watts and changing the conveyance speed in the range of 10 meters (m) / minute to 50 meters / minute. went. And the packaging bag was manufactured similarly to the above from the obtained film, and the same opening test and the drop impact test were implemented. The result is shown in FIG. As can be seen from FIG. 5B, when the conveyance speed was 10 m / min, 6 bags out of 10 in the drop impact test could not withstand the impact and burst. This is presumed to be due to the fact that when the conveyance speed is 10 m / min, the conveyance speed is slow, so the energy of the laser applied to the unit area of the film surface is high, and the LLDPE layer has melted.
[0039]
As described above, since the laser processing on the film is performed by melting the film by laser irradiation, the temperature of the laser irradiation portion varies depending on the intensity of the irradiated laser. Therefore, the laser processing state can be evaluated by detecting the temperature of the workpiece at the irradiation position instead of measuring the laser intensity.
[0040]
【The invention's effect】
As described above, according to the invention described in any one of claims 1 to 7, since the measured temperature of the surface of the workpiece represents the machining state including the laser intensity, the machining state of the machining portion is determined. Can be detected directly. In addition, various processing such as half-cutting of the resin film becomes possible. Furthermore, the machining state can be detected without affecting the workpiece. Further, laser processing of the resin film can be easily performed.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a laser processing apparatus and a management apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram showing an example of a laser processing method.
FIG. 3 is a view showing a molten state of a resin film layer by laser processing.
FIG. 4 is a diagram showing a relationship between laser power and a state of a workpiece in a laser processing method.
FIG. 5 is a diagram showing the results of an opening test and a drop impact test of a laser-processed resin film packaging bag.
[Explanation of symbols]
2 ... Infrared camera 4 ... Objective lens 5 ... Line management device 10 ... Resin film L ... Laser light

Claims (7)

In a method for detecting a processing state in laser processing in which processing is performed on a workpiece by laser irradiation, the workpiece is formed of a multilayer film including resin films having different laser absorbability, and the workpiece at the irradiation position of the laser A method for detecting a laser processing state, wherein the melt state of the resin film of each layer is detected by measuring the surface temperature of the substrate in a non-contact manner. In a method for detecting a processing state in laser processing in which processing is performed on a workpiece by laser irradiation, the workpiece is formed of a multilayer film including a resin film having a laser absorptivity at least in one layer, and the laser irradiation position is A laser processing state detection method, wherein the melting state of the resin film of each layer is detected by measuring the surface temperature of the workpiece without contact. The laser processing state detection method according to claim 2 , wherein the laser is a carbon dioxide laser. The resin film of the workpiece made of a multilayer film comprising a laser-absorbent resins having different film, a laser processing apparatus which performs relays The processing by the laser irradiation, the workpiece in the irradiation position of the laser A temperature detection device that detects the temperature of the surface, and a control that detects the melting state of the resin film of each layer according to the output of the temperature detection device and controls the intensity of the laser in the laser processing device based on the detection result A laser processing system comprising: an apparatus;   The laser processing system according to claim 4, wherein the intensity of the laser is controlled so as to obtain a predetermined processing depth or processing width for a predetermined resin film. A laser processing apparatus for performing laser processing by laser irradiation on a resin film of a multilayer film including a resin film having a laser absorption property at least in one layer, and the workpiece at the irradiation position of the laser A temperature detection device that detects the temperature of the surface, and a control that detects the melting state of the resin film of each layer according to the output of the temperature detection device and controls the intensity of the laser in the laser processing device based on the detection result A laser processing system comprising: an apparatus; The laser processing system according to claim 6 , wherein the laser is a carbon dioxide laser.

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