JP2007330970A - Colored marking method by laser - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of performing laser marking not on the surface but in the interior of transparent goods formed of polyamide resin, by Nd-YAG laser. <P>SOLUTION: The transparent goods formed of polyamide resin is used as the object of working, and laser marking is performed by a pulse-like Nd-YAG laser with a Q switch, while matching laser strength, operating conditions, etc. with the sizes of marked characters, figures, symbols, etc to be marked. Furthermore, by performing the laser marking duplicatively on the marking pattern by changing the laser strength, operating conditions, etc., the laser making with visibility in the interior of the transparent goods formed of polyamide resin is made possible. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a colored marking method for the inside of a transparent polyamide resin molded product using an Nd-YAG laser.

Unlike ordinary light such as sunlight, a laser has (1) monochromaticity, (2) directivity (straight forward), and (3) coherence (coherent). Utilizing the nature of this laser, lasers are widely used for information communication, machining, surgical scalpels and the like. Substances that produce lasers are called media, and laser media can be solid, liquid, or gas depending on the application. A high-power laser for material processing is a carbon dioxide gas laser whose medium is a gas, and YAG (yttrium aluminum garnet) whose medium is a solid is used for a surgical laser knife. Laser (LASER) is also called laser light, but here it is simply referred to as laser or laser beam.

Laser marking is a method of engraving letters and symbols on the surface of a component, and there are sculptures that make grooves on the surface, discoloration that alters and oxidizes the surface, and thin film removal that removes only the thin film on the surface. In this marking, there is a scanning method in which the spot diameter of the focused laser is used as the thickness of the character to be engraved, and a free character or picture can be drawn on any material by computer control. The outline is shown in FIG. In addition, there is a mask system in which a mask containing characters and designs can be radiated with a laser to burn the mask onto the surface of a component. The outline is shown in FIG. Laser marking has advantages such as (1) non-contact (2) easy control and automation by computer (3) no pre-processing and ink required (4) high speed and high efficiency compared to conventional printing and engraving. is there.

In general, when laser marking is performed on a resin molded product by a laser, it is necessary that the energy of the laser is absorbed by the resin molded product, and the material is volatilized or the material is altered in accordance with the purpose. The processing result depends on the physical and chemical characteristics of the resin material, the wavelength of the laser, the output, the pulse conditions, and the processing speed and other processing conditions. In particular, in the case of a transparent resin material, it is difficult to set an appropriate laser condition because the laser is easily transmitted as it is. Therefore, in laser marking of transparent resin, a coloring material is added to the transparent resin material, or a resin material having a high laser absorption rate is mixed in the base material.
Prior art documents include a method of adding an additive that discolors or develops a color when absorbed by a laser (Patent Documents 1 and 2), and a method of adding a resin material having a high laser absorption rate to a base material (patent There is a method of using an excimer laser as a laser marking of transparent resin. In this method, an organic polymer is excited by an excimer laser, an intermolecular bond is broken, a constituent molecule is decomposed, and gasification is performed. (Patent Document 5)

Furthermore, a method of black laser marking by irradiating the surface of a transparent polycarbonate molded product with a Q-switched YAG laser having a wavelength of 1.06 μm has been proposed (Patent Document 6).
JP 2001-59032 A JP 2000-344992 A JP 2002-2265774 A JP 2004-267458 A JP 2003-103392 A JP 2003-136261 A Laser Science NHK Books by Haruna Muneharu

However, these proposals and the like are limited to laser marking the surface of a resin molded product, and are not a method of laser marking the inside of a resin molded product. On the other hand, although there is a prototype for laser marking on the inside rather than the surface of an acrylic resin, a specific method using an Nd-YAG laser is not shown. As a result of trial and error, the inventor has found a method of performing laser marking using an Nd-YAG laser not inside the surface of the resin molded product but inside the resin molded product, although the type of resin is limited.

  The problem to be solved is that even though laser marking can be performed on the surface of the resin molded product, laser marking cannot be performed on the inside thereof.

The main feature of the present invention is that the laser can reach the inside of the resin molded product, not the surface of the resin molded product, and laser marking can be performed inside the resin molded product. That is, the invention of claim 1 is a laser marking method in which a transparent polyamide resin molded product is irradiated with an Nd-YAG laser having a wavelength of 1.06 μm, and a colored marking is applied to the inside of the transparent polyamide resin molded product. The polyamide resin is also called so-called nylon. The polyamide resin is made transparent by a chemical reaction such as copolymerization. An Nd-YAG laser generator 8 is shown in FIG. Nd in this Nd-YAG is neodymium, which is a solid medium in which Nd ions are mixed into YAG, and is called an Nd-YAG rod 12. In FIG. 3, a laser diode 14 as a flash lamp excites an Nd-YAG rod to generate photons, which are reflected and amplified by the HR mirror 17 and the output mirror. Then, the continuous laser is converted into a pulse laser having a high peak power by the Q switch 15, and the laser 1 goes out of the output mirror. This is because the output mirror has a mechanism that reflects part of the light and allows strong light to pass through. The shutter is for controlling laser transmission. A laser output of about 50 W is suitable, but it depends on the marking line width, processing speed, and the like.
In the invention of claim 2, after the laser marking is performed on the transparent polyamide resin molded product by determining the operating speed, frequency and flash lamp current conditions of the Nd-YAG laser having a wavelength of 1.06 μm according to the size of the pattern to be laser-marked Further, an Nd-YAG laser with a wavelength of 1.06 μm is overlapped on the marking pattern, and laser marking is performed by changing the operating conditions, frequency, and flash lamp current of the Nd-YAG laser with a wavelength of 1.06 μm. The method according to Item 1.
Laser marking patterns include letters and figures. The laser operating speed refers to the speed of the Nd-YAG laser moving on the workpiece, and its unit is mm / sec. Frequency is the number of laser pulses per second and is expressed in KHz. The current of the flash lamp is a current value that flows through the flash lamp in order to excite the Nd-YAG rod. Here, the current value that flows through the laser diode is indicated by A (ampere). The marking pattern is a pattern drawn inside the transparent polyamide resin molded product by the previous laser marking. This is because the laser pattern is overlapped and colored on the same pattern to enhance visibility. When laser marking is performed in duplicate, laser marking may be performed with the same operating speed, frequency, and flash lamp current conditions, or laser marking may be performed by changing any or all of these values. However, care should be taken because the number of laser markings may be increased or the operating speed, frequency, and flash lamp current values may be changed, resulting in laser marking on the surface, not on the inside of the transparent polyamide resin molded product. . If a marking pattern is input to the marking pattern input unit 10, the galvanometer is operated and the Nd-YAG laser moves on the transparent polyamide resin molded product, so it is possible to perform laser marking on the marking pattern in an overlapping manner. is there.
In the invention of claim 3, when the first step of laser marking on the transparent polyamide resin molded article is the first step, and the step of laser marking overlapping the marking pattern is the second step, Nd- 3. The method according to claim 2, wherein the laser marking is performed as follows for each of the operating speed, frequency and current of the flash lamp of the YAG laser.
First step Operation speed 110mm / sec Frequency 1.0KHz Flash lamp current 11A
Second step Operation speed 30mm / sec Frequency 1.0KHz Flash lamp current 10A
In addition, the numerical value in each process is a numerical value in the control panel of the laser output control part of a laser marking apparatus, and has a tolerance.
The reason why the process is divided into the first process and the second process is to perform laser marking by changing the conditions of the Nd-YAG laser in order to increase the visibility by the pattern to be laser marked. This second step may be laser-marked not only once but repeatedly in a marking pattern.
The invention of claim 4 is a transparent polyamide resin molded article colored and colored by the method of claim 1, claim 2 or claim 3. The object is a transparent polyamide resin molded product processed by the method of claims 1 to 3.

  The present invention enables laser marking with an Nd-YAG laser not inside the surface of a transparent polyamide resin molded product but inside. Therefore, the surface of the molded product is flat, so that dirt and the like are not easily attached, and a new laser marking method is presented.

  Representative examples of the present invention are shown below.

  FIG. 4 is a schematic diagram of an apparatus for carrying out the present invention. The laser output control unit 9 can determine the laser output. A laser whose output is determined is emitted from a laser generator. A marking pattern is input in the marking pattern input unit 10, and based on the result, the galvanometer 2 moves the X deflection reflecting mirror 3 and the Y deflection reflecting mirror 4 to irradiate the workpiece while changing the direction of the laser. The laser irradiated to the workpiece reaches a certain depth from the surface of the molded product because the workpiece is transparent, and the resin inside the molded product is modified and discolored by the heat of the laser. Therefore, marking can be performed inside the molded product. Instead of using a galvanometer to move the laser using the X deflection reflector and Y deflection reflector as shown in FIG. 4, the laser input / output is fixed and the reflector is used as shown in FIG. There is also a method in which the workpiece is mounted on an XY table, the workpiece is moved, and laser marking is performed with an Nd-YAG laser.

  FIG. 5 shows a molded article laser-marked according to the present invention. (1) Perspective view, (2) Front view, (3) Side view. Enter the character size in the marking pattern input section. As shown in FIG. 6, the character size was 2 mm in height, 2 mm in width, and 1 mm in character spacing. Next, the operating speed, frequency, and current value of the flash lamp are input to the laser output control unit. This time, a transparent polyamide resin molded product with a thickness of about 3 mm is laser-marked once in the first step of claim 3, and then the marking pattern is overlapped in the second step of claim 3 and laser-marked six times. did. When the laser was irradiated once in the first step, a light letter floated inside the transparent polyamide resin molded product. Next, when the marking pattern was repeatedly laser-marked in the second step, black characters gradually emerged. When viewed from the side, laser marking under this condition was able to form a pattern at a central portion of the plate thickness of 3 mm, that is, a depth of about 1.5 mm from the surface. If laser marking in the second step is repeated 7 times or more with the size of this character, the surface of the transparent polyamide resin molded product is modified by the laser to become uneven, and characters are written on the surface. . Therefore, in order to mark a pattern with high visibility, the second process is limited to 6 times. As described above, the marking pattern can be formed inside the transparent polyamide resin molded product by changing the laser marking conditions depending on the size of the marking pattern.

Many laser marking methods have been proposed. However, the conventional method has been to mark the material surface. In the present invention, although the types of resin to be processed are limited, it is shown that laser marking can be performed inside a resin molded product, and in the future, laser marking of other types of resin inside the prototype and its application are expected. The

Scanning method Mask method Laser generator Schematic diagram of laser marking device Laser-marked molded product Character size XY table laser marking device

Explanation of symbols

1 Laser Beam 2 Galvanometer 3 X Deflection Mirror 4 Y Deflection Mirror 5 Objective Lens 6 Workpiece (Workpiece)
7 Mask 8 Laser generator 9 Laser output control unit 10 Marking pattern input unit 11 Mark 12 by laser 12 Nd-YAG rod 13 HR mirror 14 Laser diode (flash lamp)
15 Q switch 16 Shutter 17 Output mirror 18 Reflecting mirror 19 Beam expander 20 XY table

Claims (4)

  A laser marking method in which a transparent polyamide resin molded product is irradiated with an Nd-YAG laser having a wavelength of 1.06 μm, and colored marking is applied to the inside of the transparent polyamide resin molded product. Depending on the size of the pattern to be laser-marked, the operating speed, frequency and flash lamp current of the 1.06 μm wavelength Nd-YAG laser are determined and laser marking is performed on the transparent polyamide resin molded product. 2. The method of claim 1, wherein the Nd-YAG laser having a wavelength of 1.06 [mu] m is laser-marked by changing the operating conditions, frequency and flash lamp current of the Nd-YAG laser having the same wavelength or 1.06 [mu] m. When the first laser marking process on the transparent polyamide resin molded product is the first process and the second laser marking process on the marking pattern is the second process, the operation speed and frequency of the Nd-YAG laser in each process 3. The method according to claim 2, wherein each of the conditions of the current of the flash lamp is laser-marked as follows.
First step Operation speed 110mm / sec Frequency 1.0KHz Flash lamp current 11A
Second step Operating speed 30mm / sec Frequency 1.0KHz Flash lamp current 10A
In addition, the numerical value in each process is a numerical value in the control panel of the laser output control part of a laser marking apparatus, and has an error. A transparent polyamide resin molded article colored and colored by the method of claim 1, 2 or 3.

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