JPH07204871A - Marking method - Google Patents

Abstract

PURPOSE:To provide a method with which bright markings having good quality free from unequalness are obtainable and which is capable of reducing a cost and is particularly adequate for graduation marking of a dial. CONSTITUTION:A black anodized aluminum layer 11 is an aluminum oxide layer having a porous structure formed by subjecting the surface of an aluminum plate as a dial to an anodized aluminum treatment and is colored by putting a black dye soln. into its pores. The coating film parts at irradiated points are evaporated and removed by heat of a laser beam when the coating film 12 is irradiated with the laser beam under scanning. The parts 13 where the coating film is removed are thus formed according to the shapes of scale lines and various codes. Consequently, the black anodized aluminum layer 11 is exposed. The blank of the coating film 12 which is apparently white is subjected to black marking with the black anodized aluminum layer of the shapes corresponding to the shape of the parts 13 where the coating film is removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a laser marking method suitable for writing a good-quality scale on a scale plate of an indicator such as an ammeter or a voltmeter.

[0002]

2. Description of the Related Art Heretofore, a method for writing a scale on a scale plate has been done by printing or handwriting a code and the like to be written together with the scale line. Recently, a method of writing a scale line or a code by irradiating a laser beam, that is, a marking method using a laser has been adopted. One of them is to black anodize the surface of the aluminum scale plate and remove the black alumite layer with heat from laser light to expose the aluminum base and mark it with the white color of the base. Is the way. The other is to form two layers of black and white coating on the surface of the metal scale plate in order and expose the black coating by removing the white coating on the surface with heat from laser light. This is a method of marking black on the apparently white base material.

[0003]

The conventional method has the following problems. In the printing method, many kinds and small amounts are walls, which often does not match the cost. The handwriting method requires the skill of an expert and generally requires a long manufacturing process. In the first method using laser light, the exposed aluminum base that is the marking portion is easily corroded, and in the second method, the heat of the laser light vaporizes a part of the black coating film, and the vaporized particles become white. It adheres to the coating film and contaminates, degrading the marking quality.

The problem to be solved by the present invention is to solve the above problems of the prior art, to obtain clear and good quality marking without unevenness, and to reduce the cost, especially for the scale plate. An object of the present invention is to provide a laser marking method suitable for scale marking.

[0005]

SUMMARY OF THE INVENTION The present invention is a method of applying a coating film on a colored aluminum work that has been treated with marumite and irradiating the surface of the workpiece with laser light while scanning it to remove the portion of the coating film at the irradiated location. Is. In particular, the coating film has a thickness of 5 to 40 μm, the marking is graduated, and the laser light is a YAG laser of repetitive pulses by a Q switch under continuous excitation.

[0006]

In this invention, when the surface of the work is irradiated with laser light while being scanned, the portion of the coating film at the irradiated position is vaporized and removed by the heat of the laser light, and the base of the colored alumite does not discolor. Exposed. As a result, the marking of the color of the colored alumite is apparently applied to the color substrate of the coating film.

[0007]

Embodiments of the marking method according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view of a marking portion. In FIG. 1, 11
Is a black anodized layer, and 12 is a white coating film. Here, the black alumite layer 11 is basically an aluminum oxide layer formed by alumite treatment on the surface of a work of an aluminum plate which is a scale plate. Alumite treatment is also referred to as anodizing treatment of aluminum, and is a treatment in which fully degreased aluminum or aluminum alloy is used as an anode for electrolysis in a dilute acid, and oxygen generated at that time forms a film of aluminum oxide on the surface. .
Since the aluminum oxide layer formed by the alumite treatment has corrosion resistance and a porous structure, it can be colored by putting a dye solution in the pores. That is, in this case, the aluminum oxide layer is colored by the black dye. Moreover, this coloring does not come off.

By the way, when the coating film 12 of FIG. 1 is irradiated with laser light while scanning, the coating film portion of the irradiated portion is vaporized and removed by the heat of the laser light, and the scale line and the shapes of various symbols are changed. The coating film removing portion 13 is formed. As a result, the black alumite layer 11 is exposed, and apparently the white base material of the coating film 12 is marked with a shape corresponding to the coating film removing portion 13 of the black alumite layer. Moreover, the black alumite layer 11 is hard to be vaporized by the irradiation of the laser beam whose output is properly adjusted. Therefore, the vaporized particles adhere to the coating film 12 to contaminate it or make it bleed, thereby marking quality. There is no fear of lowering.

Next, appropriate processing conditions for good marking will be described with reference to FIG. FIG. 2 is a state diagram showing an appropriate processing range in which the coating film thickness and the laser output are variables. Coating thickness (μm) on the vertical axis
When the laser output (W) is taken on the horizontal axis, there are four states: coating remaining, proper processing state, alumite burning, and coating sheer according to the relationship between coating thickness and each value of laser output. Become. As shown in FIG. 2, the range of the four states is shown with the coating film thickness and the laser output as variables.

In the figure, when the thickness of the white coating film is 5 μm or less, the color of the black alumite layer can be seen from the beginning, and as a result, the entire scale plate looks gray to some extent. This is the state where the coating film is transparent, which is a poor marking. When the coating thickness is 40 μm or more, the coating cannot be completely removed when the laser output is low and the coating remains, and when the laser output is high, the alumite layer is thermally discolored or damaged. It becomes an alumite burnt state, and it is very difficult to adjust the laser output to obtain an appropriate intermediate state. Marking is not good in both cases of coating residue and alumite burning. According to the embodiment, when the coating film thickness is 5 to 40 μm, the coating film remains due to the relatively easy selection of an appropriate laser output according to the thickness.
Properly processed state that is neither anodized nor burned, that is, good marking can be obtained. The widest range of laser output to obtain a proper processing state is that the coating thickness is 2
It was at 0 μm. By the way, in general, the color of the alumite layer can be freely selected, and the color of the coating film is also the same.
It is possible to optimize the combination of the base color and the marking color according to the purpose and application of marking.

An apparatus used for marking will be described with reference to the block diagram of the marking apparatus shown in FIG.
In the figure, laser light emitted from the laser oscillator 1 for YAG laser is oscillated by the deflection mirrors 2u and 2v at right angles to each other, and irradiates the surface of the work 10 through the fθ lens 3. That is, the irradiation spot of the laser light is scanned on the surface of the work 10 by the respective deflection mirrors 2u and 2v, and the portion of this scanning locus is shallowly engraved and marked by the thermal action of the laser light. The fθ lens 3 is a special condensing lens, which deflects the laser light, which is oscillated by the deflection mirrors 2u and 2v and enters at a relatively large incident angle, to a position corresponding to the incident angle and focuses the laser light.

Each deflection mirror 2u, 2v is directly connected to each corresponding actuator 5u, 5v. This each actuator
The positions (rotation angles) of 5u and 5v are controlled by the control unit 6. The rotation axis of the deflection mirror 2u is an axis that passes through the central portion and is perpendicular to the paper surface. The rotation axis of the deflection mirror 2v is a central axis included in the mirror surface and parallel to the paper surface. Therefore,
The laser beam is swung in the X-axis direction on the surface of the work 10 by the rotation of the deflection mirror 2u, and the Y-axis (perpendicular to the paper surface) on the surface of the work 10 by the rotation of the deflection mirror 2v.
Will be shaken in the direction.

By the way, the laser light emitted from the laser oscillator 1 is a YAG laser having a repetitive pulse by a Q switch under continuous excitation, and in that case, a YAG rod is irradiated with the excitation light by an excitation lamp. The laser output can be finely adjusted by the current (excitation current) and the repetition frequency of the Q switch to obtain the optimum value for the proper processing state described above.

[0014]

EFFECTS OF THE INVENTION According to the present invention, good quality markings which are generally uniform and clear and have excellent corrosion resistance can be obtained, and an object is to combine each color of the base material and the markings.
It can be freely selected to suit the application, reducing man-hours and cost. In particular, the thickness of the coating film is 5
A proper processing state can be obtained by setting the range to 40 μm. That is, when the thickness is 5 μm or less, the color of the colored alumite can be seen through the coating film on the entire surface of the work,
When the thickness is more than μm, the coating film remains or the alumite is burnt, but in the range of 5 to 40 μm, the proper processing state can be easily obtained by adjusting the laser output. Further, when used for graduation writing, the graduation lines and codes are clear and easy to see, a high level of skill of a skilled person is not required even with a small amount of various types, and the production period can be shortened. Furthermore, by using a YAG laser having a repetitive pulse by a Q switch under continuous excitation as the laser light, fine adjustment of the laser output can be facilitated and the marking conditions can be optimized easily.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a marking portion of an embodiment according to the present invention.

FIG. 2 is a state diagram showing an appropriate processing range in which coating film thickness and laser output are variables.

FIG. 3 is a block diagram of a marking device

[Explanation of symbols]

 1 Laser Oscillator 2u, 2v Deflection Mirror 3 fθ Lens 5u, 5v Actuator 6 Control Unit 10 Work 11 Black Alumite Layer 12 Coating 13 Coating Removal Part

Claims (4)

[Claims] 1. A marking method, which comprises applying a coating film on a work of colored marumite-treated aluminum and irradiating the surface thereof with a laser beam while scanning to remove a portion of the coating film at the irradiated portion. 2. The method according to claim 1, wherein the coating film comprises:
A marking method having a thickness of 5 to 40 μm. 3. The method according to claim 1 or 2, wherein
The marking method is characterized in that the marking is a scale marking. 4. A marking method according to any one of claims 1 to 3, wherein the laser light is a YAG laser of repetitive pulses by a Q switch under continuous excitation.