JP2017177152A - Laser light shielding material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser light shielding material that shows high shieldability to laser light with a short wavelength and high output, and yet has excellent portability, moldability and processability.SOLUTION: A shielding cover 6 as a laser light shielding material is constituted to include a carbon fiber-reinforced plastic having pitch-based carbon fibers oriented in at least one direction. Preferably a thickness of the shielding cover 6 is 0.5 mm or more and 10 mm or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a laser light shielding material that shields laser light.

  Conventionally, in the industrial laser field, a laser light shielding material capable of preventing laser light from leaking outside the management / working area of a laser device has been developed. Examples of the product form using the laser light shielding material include a film, a curtain, a panel, a partition, and a cabin (small room).

  In Patent Document 1, a partition in which a plurality of shielding panels are connected without causing a gap is proposed. There is a description that the shielding panel is formed of, for example, aluminum having a thickness of about 2 mm or black alumite.

JP 2009-233726 A ([0008], [0022], FIG. 2 etc.)

  Recently, with the progress of laser technology, it is becoming possible to irradiate laser light with a short wavelength and high output. Specifically, the laser wavelength of the fiber laser is about 1 μm, which is considerably shorter than that of the carbon dioxide laser (about 10 μm). That is, by using this type of laser light, the workability on the workpiece is improved, but it is necessary to introduce a laser light shielding material having a higher shielding property.

  However, when a high-power laser beam having a wavelength of about 1 μm is irradiated on the partition described in Patent Document 1, specifically, aluminum having a thickness of 2 mm, it penetrates in a very short time (for example, several seconds). . In other words, taking into account the current level of laser technology, there is a possibility that the required specifications related to shielding are not satisfied, depending on the usage status of the laser equipment.

  As one of countermeasures, it is conceivable to employ a material (specifically, iron or concrete) that has a higher shielding property against laser light than aluminum. However, since the generally known shielding material has a large specific gravity, there is a problem that the weight rapidly increases as the area and thickness increase, and the portability decreases accordingly.

  The present invention has been made in view of the above-described problems, and has a high shielding property against laser light having a short wavelength and a high output, and is excellent in portability, moldability, and workability. The purpose is to provide.

  The “laser light shielding material” according to the present invention includes a carbon fiber reinforced plastic in which pitch-based carbon fibers are oriented in at least one direction. A carbon fiber reinforced plastic in which pitch-based carbon fibers are oriented in at least one direction is a material having a higher thermal conductivity and a higher heat resistance than a generally known shielding material. That is, even when laser light having a short wavelength and high output is irradiated, melting / outflow of the irradiated portion is remarkably suppressed. Furthermore, this carbon fiber reinforced plastic is light in weight because it has a smaller specific gravity than a general shielding material, and has the advantage of being easily molded or processed into an arbitrary shape. Thereby, it is possible to provide a laser light shielding material having a high shielding property against laser light having a short wavelength and a high output, and having excellent portability, moldability and workability.

  The thickness is preferably 0.5 mm or more, and more preferably 3 mm or more. As a result, a sufficiently high shielding property against a short wavelength and high output laser beam can be secured.

  Moreover, it is preferable that thickness is 10 mm or less. In general, since carbon fiber reinforced plastic is an expensive material, an increase in the manufacturing cost of the laser light shielding material can be suppressed by reducing this amount of use.

  The pitch-based carbon fibers are preferably oriented in a plurality of directions at equal angular intervals. Since heat conduction occurs along the length direction (that is, the radial direction) of the carbon fiber, the heat dissipation performance is increased accordingly. Since the shielding material is prevented from melting and flowing out by the exhaust heat effect at and near the irradiated portion, the shielding property of the laser beam can be maintained.

  Moreover, it is preferable that the shielding surface which shields a laser beam has the surface shape in which the unevenness | corrugation which has a one-dimensional or two-dimensional periodicity was formed. By providing periodic irregularities on the shielding surface, the surface area increases substantially uniformly, and the energy density of the laser beam (the amount of energy per unit area) decreases accordingly. Thereby, the shielding property against the laser light is further enhanced regardless of the irradiation position.

  Moreover, it is preferable that the height difference of the unevenness is smaller than the width of the unevenness. By making the height difference relatively small, it becomes easy for heat generated by the unevenness to escape to the vicinity thereof, so that melting / deformation near the surface of the unevenness is difficult to occur. As a result, the energy density reduction effect described above is easily maintained as it is.

  Moreover, it is preferable to shield the laser beam by a fiber laser. By using a fiber laser, it is possible to irradiate a laser beam having a short wavelength and a high output, and thus the above-described shielding effect appears remarkably.

  According to the present invention, it is possible to provide a laser light shielding material that has high shielding properties against laser light having a short wavelength and high output, and that is excellent in portability, moldability, and workability.

It is a whole block diagram of the laser processing system incorporating the laser beam shielding material according to this embodiment. 2A to 2D are partial enlarged cross-sectional views of the shielding cover shown in FIG.

[Characteristics of laser light shielding material]
The laser light shielding material according to this embodiment is a member that prevents the laser light from leaking outside the management / work area of the laser device. Examples of the product form using the laser light shielding material include a film, curtain, case, panel, partition, cabin, cell, and shielding cover 6 (FIG. 1) described later. Further, the laser light shielding material may be incorporated in a passive system having a simple shielding function, or incorporated in an active system that performs an operation to cope with laser irradiation (for example, detection, stop, and notification). Also good.

  Examples of laser types include solid-state lasers, fiber lasers, free electron lasers, chemical lasers, gas lasers, semiconductor lasers, and liquid lasers from the viewpoint of the medium. Further, from the viewpoint of wavelength, an infrared laser, a visible light laser, an ultraviolet laser, and the like can be given.

  The laser light shielding material according to this embodiment includes a carbon fiber reinforced plastic (hereinafter also referred to as “pitch CFRP”) in which pitch carbon fibers are oriented in at least one direction. This pitch-based CFRP is a material having high thermal conductivity and high heat resistance as compared with a generally known shielding material. That is, even when laser light having a short wavelength and high output is irradiated, melting / outflow of the irradiated portion is remarkably suppressed. Furthermore, this carbon fiber reinforced plastic is light in weight because it has a smaller specific gravity than a general shielding material, and has the advantage of being easily molded or processed into an arbitrary shape. Thereby, it is possible to provide a laser light shielding material having a high shielding property against laser light having a short wavelength and a high output, and having excellent portability, moldability and workability.

  In particular, this laser light shielding material is used for the purpose of shielding laser light from a fiber laser. This is because, by using a fiber laser, it is possible to irradiate laser light having a short wavelength and high output, and thus the above-described shielding effect appears remarkably.

  The area or thickness of the laser light shielding material can be arbitrarily designed, but the more preferable lower limit of the thickness is 0.5 mm, 1.5 mm, 3 mm, or 4 mm, and the upper limit of the thickness is 10 mm. It is 8 mm or 6 mm. By providing a thickness of 0.5 mm or more, it is possible to ensure a sufficiently high shielding property against laser light having a short wavelength and high output. In general, since carbon fiber reinforced plastic is an expensive material, it is possible to suppress an increase in the manufacturing cost of the laser light shielding material by reducing the amount of use by providing a thickness of 10 mm or less.

  When pitch-based carbon fibers are oriented in two directions, the orientation angles are preferably 0 degrees and 90 degrees (tolerance is approximately ± 5 degrees). Alternatively, when the pitch-based carbon fibers are oriented in four directions, the orientation angles are preferably 0 degrees, 45 degrees, 90 degrees, and 135 degrees (tolerance is approximately ± 5 degrees). As described above, by orienting the pitch-based carbon fibers in a plurality of directions at equal angular intervals, heat conduction occurs along the length direction (that is, the radial direction) of the carbon fibers, and the heat dissipation increases accordingly. . Since the shielding material is prevented from melting and flowing out by the exhaust heat effect at and near the irradiated portion, the shielding property of the laser beam can be maintained.

Since this laser light shielding material has the above-described characteristics, it can satisfy the following virtual requirement specifications, specifically, the requirement specification considering the current level of laser technology.
・ Laser output: 5kW
・ Laser wavelength: around 1 μm ・ Spot diameter: 30 mmφ
・ Irradiation time: 50 s or more (more preferably, 100 s or more)

[Application example of laser light shielding material]
FIG. 1 is an overall configuration diagram of a laser processing system 1 incorporating a laser light shielding material according to this embodiment. The laser processing system 1 is a system for processing a workpiece W such as metal (for example, copper, aluminum) on the work table S. The laser processing system 1 basically includes a fiber laser device 2 that generates laser light L, a laser processing head 3 that outputs laser light L, and an optical connection between the fiber laser device 2 and the laser processing head 3. An optical fiber cable 4 is provided.

  The tip portion 5 of the laser processing head 3 is disposed under a position / attitude facing the main surface of the workpiece W. Further, a trumpet-shaped shielding cover 6 (laser light shielding material) is attached to the laser processing head 3 at a position covering the entire front end portion 5. That is, the shielding cover 6 functions to shield the return component of the laser light L reflected from the workpiece W or the work table S with the shielding surface 7 and prevent the laser light L from leaking outside the management / working area. Fulfill.

  For example, when the work is performed with the laser processing head 3 held by a movable arm (not shown), the irradiation direction of the laser light L can be changed, so that the possibility of the laser light L leaking under an unforeseen situation increases. In this case, a shielding cover 6 having a high shielding property for the laser light L, a small size and a light weight can be attached to the tip portion 5 of the laser processing head 3. In addition to or separately from this, a similar shielding cover may be provided around the workpiece W.

  The shielding surface 7 of the shielding cover 6 may have a flat surface shape, or may have a surface shape on which irregularities having periodicity in one or two dimensions are formed. In particular, by providing irregularities with periodicity on the shielding surface 7, the surface area increases substantially uniformly, and the energy density (energy amount per unit area) of the laser light L decreases accordingly. Thereby, the shielding property with respect to the laser beam L is further enhanced regardless of the irradiation position.

  FIG. 2 is a partially enlarged cross-sectional view of the shielding cover 6 shown in FIG. More specifically, FIGS. 2A to 2D show examples of surface shapes on the shielding surfaces 7a to 7d, respectively. In FIGS. 2A to 2C, an uneven surface treatment is applied to one main surface of the flat substrate, and in FIG. 2D, an uneven surface treatment is applied to the entire flat substrate. . The surface shape is not limited to the example shown in the figure, and any irregular shape may be adopted.

  A rectangular concave portion (or convex portion) having a width of W and a height difference of H is formed on the shielding surface 7a illustrated in FIG. On the shielding surface 7b shown in FIG. 2B, triangular convex portions (or concave portions) having a width W and a height difference H are formed. On the shielding surface 7c shown in FIG. 2C, a hemispherical recess having a width W and a height difference H is formed. On the shielding surface 7d shown in FIG. 2D, a sinusoidal recess having a width W and a height difference H is formed.

  In addition, the shielding surfaces 7a to 7d have a surface shape capable of obtaining an effect of suppressing melting / outflow of the irradiated portion. Specifically, the width W and the height difference H are both larger than the wavelength of the laser beam L (about 1 μm for the fiber laser and about 10 μm for the carbon dioxide laser) and 10 mm (approximately the same as the spot diameter of the laser beam L). Preferably it is smaller.

  Further, the height difference H of the unevenness may be provided smaller than the width W of the unevenness. By making the height difference H relatively small, heat generated by the unevenness can be easily released to the vicinity thereof, so that melting and deformation near the surface of the unevenness are hardly caused. As a result, the energy density reduction effect described above is easily maintained as it is.

[Laser light shielding material manufacturing method]
The laser light shielding material according to this embodiment has the above-described structural characteristics or physical characteristics. Then, the manufacturing method of the laser beam shielding material which concerns on this embodiment is demonstrated.

<Pitch-based carbon fiber>
Examples of the raw material for the pitch-based carbon fiber include a condensed polycyclic hydrocarbon compound containing naphthalene or phenanthrene, a condensed heterocyclic compound containing petroleum-based pitch or coal-based pitch. These may be used individually by 1 type, or may be used in combination of 2 or more types as appropriate. Particularly regarding the anisotropic pitch system, the density of the carbon fiber is 1.7 to 2.2 g / cm ³ , and the fiber shape is longer than that of the isotropic pitch system.

<Prepreg>
A prepreg is an intermediate material for molding formed by impregnating pitch-based carbon fibers with a matrix resin to form a sheet. The type of prepreg may be any of a unidirectional prepreg, a cross prepreg, and a woven prepreg. “One-way prepreg” is a prepreg in which pitch-based carbon fibers are oriented in one direction. The “cross prepreg” is a prepreg in which pitch-based carbon fibers are oriented in a plurality of directions. The “woven fabric prepreg” is a prepreg in which pitch-based carbon fibers are plain-woven, twill-woven, or satin-woven.

  Examples of the matrix resin used for the prepreg include an epoxy resin, an unsaturated polyester resin, a phenol resin, and a polyimide resin. For example, when the matrix resin is an epoxy resin composition, it is composed of an epoxy resin component, a curing agent component, and other components.

  Specific examples of the epoxy resin component include a glycidyl ether obtained from a polyol, a glycidyl amine obtained from an amine having a plurality of active hydrogens, a glycidyl ester obtained from a polycarboxylic acid, and a compound having a plurality of double bonds in the molecule. Examples include polyepoxide obtained by oxidation. For example, [1] bisphenol type epoxy resin such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, tetrabromobisphenol A type epoxy resin, [2] phenol novolac type epoxy resin, cresol novolac type epoxy A novolak-type epoxy resin such as a resin, [3] glycidylamine-type epoxy resin such as tetraglycidyldiaminodiphenylmethane, triglycidylaminophenol, tetraglycidylxylenediamine, or [4] a combination thereof is preferably used.

  As the curing agent component, a compound having an active group capable of reacting with an epoxy group is used. For example, as an amine-based curing agent, [1] aliphatic amines such as ethylenediamine, diethylenetriamine, triethylenetetramine, hexamethylenediamine, m-xylylenediamine, [2] metaphenylenediamine, diaminodiphenylmethane, diaminodiethyldiphenylmethane, Aromatic amines such as diaminodiethyldiphenylsulfone, tertiary amines such as [3] benzyldimethylamine, tetramethylguanidine, 2,4,6-tris (dimethylaminomethyl) phenol, bases such as [4] dicyandiamide Active hydrogen compounds, [5] organic acid dihydrazides such as adipic acid dihydrazide, and [6] imidazoles such as 2-methylimidazole and 2-ethyl-4-methylimidazole.

  In addition, by selecting or adding various components, the finished laser light shielding material can be provided with functions of flame retardancy, low light absorption, and smoke generation (low smoke generation or high smoke generation). Good.

<Molding process>
After laminating the obtained prepreg, the pitch-based CFRP is completed by performing various molding processes. As molding methods, [1] Indirect molding methods such as internal pressure molding method, autoclave molding method, oven molding method, sheet wrapping molding method, etc. [2] Filament winding method, pultrusion molding method, RTM (Resin Transfer Molding) method, etc. Direct molding method.

  Next, specific examples of the present invention will be described. It should be noted that the present invention is not limited to these examples.

<1. Preparation of sample piece>
First, a total of nine types of sample pieces were prepared for evaluation of the shielding property of laser light. The sample pieces of Examples 1 and 2 and Comparative Examples 1 to 7 shown below are all square-shaped panel members in plan view.

(Examples 1 and 2)
A four-direction (0 degree / 45 degree / 90 degree / 135 degree) cross prepreg in which an epoxy resin (manufactured by Mitsubishi Rayon Co.) was impregnated into a pitch-based carbon fiber base material “DIALEAD” manufactured by Mitsubishi Rayon Co., Ltd. was produced. And after laminating this four-way cross prepreg, the pitch system is 4 mm (18 layers; Example 1), 6 mm (26 layers; Example 2) by forming into a flat plate shape using an autoclave method. Each CFRP was produced. A part of this CFRP was cut to obtain a sample piece having a side length of 300 mm.

(Comparative Example 1)
A part of “Ever-Guard” (registered trademark) manufactured by KENTEK, USA was cut to obtain a sample piece having a side length of 75 mm. This sample piece is mainly made of aluminum and has a thickness of 1 mm.

(Comparative Example 2)
A part of “BM2.M5P06.5003 (Extendable Laser Safety panel 3-panel system)” manufactured by Laserservation, Germany was cut to obtain a sample piece having a side length of 150 mm. This sample piece is mainly made of aluminum and has a thickness of 3 mm.

(Comparative Example 3)
A part of an oriented strand board (OSB) that is widely commercially available was cut to obtain a sample piece having a side length of 300 mm. This sample piece is mainly made of a piece of wood (strand) and has a thickness of 11 mm.

(Comparative Examples 4 and 5)
A part of “Maftec” (registered trademark) manufactured by Mitsubishi Plastics Co., Ltd. was cut to obtain a sample piece having a side length of 300 mm. The sample piece of Comparative Example 4 (1600 board) has mullite as the main mineral composition and a thickness of 50 mm. The sample piece of Comparative Example 5 (1700 board) has α-alumina as the main mineral composition and a thickness of 50 mm.

(Comparative Examples 6 and 7)
Part of pitch CFRP “ME15” (Comparative Example 6) and “ME30” (Comparative Example 7) manufactured by Mitsubishi Chemical Corporation was cut to obtain a sample piece having a side length of 300 mm. Each of these pitch-based CFRPs is a composite material produced by using an injection molding method after dispersing short fiber pellets (15% content in Comparative Example 6 and 30% content in Comparative Example 7) in polycarbonate. is there. Each of these sample pieces has a thickness of 3 mm.

<2. Experimental procedure>
With reference to a test method defined by IEC (International Electrotechnical Commission), which is an international standard, an evaluation experiment was performed on nine types of sample pieces. This method is shown in “Annex D” of IEC 60825-4 (Laser Product Safety—Part 4: Laser Guard).

  Each sample piece is disposed to face a fiber laser device (manufactured by IPG Photonics, USA) having an output of 5 kW. By providing a condensing lens at the irradiation destination of the fiber laser device, the irradiation spot diameter of the laser light was adjusted to (1) 20 mmφ and (2) 40 mmφ. A burn paper is arranged behind the sample piece so that it can be determined whether or not the laser beam has penetrated the sample piece.

<3. Evaluation method>
With respect to each sample piece, a “penetration time” (unit: s), which is a required time from the start of laser beam irradiation to the penetration through the sample piece, was measured. It can be said that the shorter the penetration time, the lower the shielding property of the laser beam, and the longer the penetration time, the higher the shielding property of the laser beam. From the practical viewpoint, the upper limit of the irradiation time was set to 150 s. This upper limit value sufficiently exceeds the required specification 100s.

  Moreover, the penetration time per unit thickness (B / A, unit: s / mm) was determined by dividing the penetration time (B) by the thickness (A). It can be said that the smaller this value (B / A), the lower the shielding property of the laser beam, and the larger the value (B / A), the higher the shielding property of the laser beam.

<4. Result>
Table 1 shows the experimental results when the laser beam output is 5 kW and the spot diameter is 20 mmφ. As understood from this table, the penetration times in Comparative Examples 1 to 7 were all less than 10 s, and sufficient shielding properties were not obtained. On the other hand, the penetration time in Example 1 was 33 s, and the penetration time in Example 2 was 78 s. It was confirmed that both had sufficient shielding properties. Similarly, regarding the value of B / A, it was confirmed that Examples 1 and 2 were significantly superior to Comparative Examples 1 to 7.

  The value of B / A = 8.3 in Example 1 is about 8 times larger than the value of B / A = 1.0 in Comparative Example 1. In other words, as far as Example 1 is concerned, if the thickness A = 4 mm, ie, A = 0.5 mm, there is a shielding property equivalent to the ready-made product (Comparative Example 1), and A> 0.5 mm If so, a higher shielding property than the ready-made product can be obtained.

Further, based on the experimental results of Example 1, a more preferable thickness (A) range is estimated. For example, it was confirmed that sufficient light shielding properties can be obtained if the above-mentioned required specifications (spot diameter: 30 mmφ, irradiation time: 50 s or more) are satisfied. A range where the value of A satisfying the following formula is the lower limit,
(30/20) ^ 2 · (33/4) = 50 / A
That is, it is more preferable that A ≧ 3 mm because sufficient light shielding properties can be obtained. Note that the multiplier (30/20) ^ 2 is a correction multiplier that takes into account changes in energy density.

  Next, Table 2 shows the experimental results when the laser beam output is 5 kW and the spot diameter is 40 mmφ. Here, the experiment was performed only on three examples (Comparative Examples 3 to 5) in which the spot diameter was doubled and the shielding performance was relatively excellent among the seven comparative examples.

  As can be understood from this table, the energy density is reduced by about 0.25 times compared to the case where the spot diameter is 20 mmφ. Shielding property was not obtained. On the other hand, in both Examples 1 and 2, it was confirmed that the laser beam was not penetrated even when the upper limit value (150 s) passed and sufficient shielding properties were obtained. Similarly, regarding the value of 0.25 · B / A, it was confirmed that Examples 1 and 2 were significantly superior to Comparative Examples 3 to 5. The multiplier 0.25 is a correction multiplier that takes into account changes in energy density.

  As described above, laser light shielding materials (Examples 1 and 2) having high shielding properties against laser light having a short wavelength and high output and excellent portability were obtained.

[Remarks]
Note that the present invention is not limited to the above-described embodiments and examples, and it is needless to say that the present invention can be freely changed without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Laser processing system 2 ... Fiber laser apparatus 3 ... Laser processing head 4 ... Optical fiber cable 5 ... Tip part 6 ... Shielding cover (laser beam shielding material)
7 (a / b / c / d) ... shielding surface L ... laser light

Claims (8)

  A laser light shielding material comprising a pitch-based carbon fiber including a carbon fiber reinforced plastic oriented in at least one direction.   The laser light shielding material according to claim 1, wherein the thickness is 0.5 mm or more.   The laser light shielding material according to claim 2, wherein the thickness is 3 mm or more.   The laser light shielding material according to claim 1, wherein the thickness is 10 mm or less.   The laser light shielding material according to any one of claims 1 to 4, wherein the pitch-based carbon fibers are oriented in a plurality of directions at equal angular intervals.   The laser beam according to claim 1, wherein the shielding surface that shields the laser beam has a surface shape in which irregularities having periodicity in one or two dimensions are formed. Shielding material.   The laser light shielding material according to claim 6, wherein a height difference of the unevenness is smaller than a width of the unevenness.   The laser light shielding material according to claim 1, wherein laser light from a fiber laser is shielded.

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