Laser bonding method

Abstract

This improves productivity when joining thermoplastic components and components to be joined. [Solution] The laser joining method comprises the steps of pressing a laser-transparent member having a self-cooling mechanism onto a thermoplastic member placed on a member to be joined, and irradiating the thermoplastic member, which is being pressed against by the laser-transparent member, with a laser through the laser-transparent member, which is in a state where the cooling function of the self-cooling mechanism is being exerted.

Description

Technical Field

[0001] The present disclosure relates to a laser bonding method.

Background Art

[0002] Patent Document 1 discloses a method in which an infrared-transmissive solid is disposed on a plurality of laminated thermoplastic resin members, and an infrared laser is irradiated onto the thermoplastic resin members from the infrared-transmissive solid side to weld the thermoplastic resin members together.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When an infrared-transmissive solid is repeatedly irradiated with an infrared laser, the infrared-transmissive solid may deteriorate due to heat. To avoid this, steps such as once separating the infrared-transmissive solid from the thermoplastic resin member, cooling the infrared-transmissive solid, and again disposing the infrared-transmissive solid on the thermoplastic resin member are required, resulting in a decrease in the productivity in welding the thermoplastic resin members.

Means for Solving the Problems

[0005] The present disclosure can be realized in the following forms.

[0006] According to one embodiment of the present disclosure, a laser joining method is provided for joining a thermoplastic member and a member to be joined by laser irradiation. This laser joining method comprises the steps of pressing a laser-transparent member having a self-cooling mechanism onto the thermoplastic member placed on the member to be joined from above, and irradiating the thermoplastic member, which is in the state in which the laser-transparent member is pressed against it, with a laser through the laser-transparent member in a state in which the cooling function of the self-cooling mechanism is being exerted. With this embodiment of the laser joining method, since the laser is irradiated onto the thermoplastic member through the laser-transparent member in a state in which the cooling function of the self-cooling mechanism is being exerted, it is possible to suppress excessive heating of the thermoplastic member, and the steps of temporarily removing the laser-transparent member from the thermoplastic member to cool it and then placing the laser-transparent member back onto the thermoplastic member are eliminated. Therefore, productivity is improved when joining a thermoplastic member and a member to be joined. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic cross-sectional view illustrating the laser bonding method in this embodiment. [Modes for carrying out the invention]

[0008] A. Embodiments: Figure 1 is a schematic cross-sectional view showing the laser bonding method in this embodiment. The laser bonding method comprises a placement step S1, a pressurizing step S2, a laser irradiation step S3, and a removal step S4. By performing steps S1 to S4, the member to be bonded 10 and the thermoplastic member 20 are bonded together. Details of each step will be described later. For the sake of explanation, in the state in which the member to be bonded 10 and the thermoplastic member 20 are stacked as shown in Figure 1, the direction from the member to be bonded 10 toward the thermoplastic member 20 is defined as the upward direction.

[0009] <Placement process S1> In step S1, a plate-shaped member to be joined 10 is placed on the substrate B, and a plate-shaped thermoplastic member 20 is placed on top of the member to be joined 10. The substrate B maintains a stable laminated state of the member to be joined 10 and the thermoplastic member 20. The material and shape of the substrate B are not particularly limited, but it is preferable that it be made of a material that does not easily deform in the pressing step S2 described later and has appropriate rigidity, and a metal plate is used as an example. The material of the member to be joined 10 is not particularly limited, but stainless steel is used in this embodiment. The type of thermoplastic member 20 is not particularly limited, but an olefin resin is used as an example. Note that the substrate B may be omitted, and for example, the member to be joined 10 may be placed directly on a workbench or the like.

[0010] <Pressurization process S2> In step S2, a plate-shaped laser-transparent member 30 is placed on the thermoplastic member 20, and pressure P is applied by pressing the laser-transparent member 30 against the thermoplastic member 20 from above. This causes the thermoplastic member 20 to adhere tightly to the member to be joined 10. The laser-transparent member 30 is preferably made of a material that is resistant to deformation under pressure, and as an example, it is made of a resin material.

[0011] <Laser irradiation process S3> In step S3, while maintaining the pressurization from step S2, the thermoplastic member 20 is irradiated with a laser L from above the laser-transparent member 30 to heat the thermoplastic member 20. The laser-transparent member 30 is used to appropriately heat the entire thermoplastic member 20 while suppressing localized high temperatures only on the laser-irradiated surface of the thermoplastic member 20. Laser irradiation is continued until the thermoplastic member 20 reaches the temperature necessary to bond it to the member to be bonded 10. The type of laser L is not particularly limited, but an infrared laser is used as an example.

[0012] The thermoplastic member 20 is pressed against the member to be joined 10 by the pressurization in step S2 and the laser irradiation in step S3. In this embodiment, the material of the member to be joined 10 was stainless steel, but the material of the member to be joined 10 may be a resin material such as a thermoplastic resin. In that case, the thermoplastic member 20 and the member to be joined 10 may be joined by welding.

[0013] If the laser-transparent member 30 is repeatedly or for a long period of time irradiated with a laser L, the laser-transparent member 30 may deteriorate due to heat. Therefore, the laser-transparent member 30 has a self-cooling mechanism 35 for cooling the laser-transparent member 30 itself, and the laser irradiation in step S3 is performed when the cooling function of the self-cooling mechanism 35 is activated. More specifically, a circular opening H for circulating cold water inside the laser-transparent member 30 is provided in the cross section of the laser-transparent member 30 as the self-cooling mechanism 35. A hose (not shown) for circulating cold water is connected to the opening H. A pump (not shown) is connected to the hose, and when the pump is operated, cold water circulates inside the opening H, and the laser-transparent member 30 is cooled. The laser irradiation in step S3 is performed when cold water is circulating inside the opening H, that is, when the cooling function of the self-cooling mechanism 35 is activated. This suppresses deterioration of the laser-transparent member 30 due to heat.

[0014] <Removal process S4> In step S4, the pressurization in step S2 and the laser irradiation in step S3 are stopped, and the laser-transparent member 30 is removed from the thermoplastic member 20. Once the temperatures of the member to be joined 10 and the thermoplastic member 20 have stabilized, the joining of the member to be joined 10 and the thermoplastic member 20 is completed. If it is to join another thermoplastic member on top of the thermoplastic member 20, the new thermoplastic member can be placed on top of the thermoplastic member 20, and steps S2 to S4 can be performed again. This makes it possible to join multiple thermoplastic members of different types.

[0015] According to the laser joining method described above, the laser L is irradiated onto the thermoplastic member 20 through the laser-transparent member 30, which is in a state where the cooling function of the self-cooling mechanism 35 is being exerted. Therefore, excessive heating of the thermoplastic member 20 can be suppressed, and the process of temporarily removing the laser-transparent member 30 from the thermoplastic member 20 to cool it and then placing the laser-transparent member 30 back on the thermoplastic member 20 is unnecessary. As a result, productivity is improved when joining the thermoplastic member 20 and the member to be joined 10.

[0016] B. Other embodiments: (B1) In this embodiment, the cross-section of the laser-transparent member 30 was provided with a circular opening H for circulating chilled water inside the laser-transparent member 30, but the disclosure is not limited thereto. Instead of providing an opening H in the cross-section of the laser-transparent member 30, a flow path for circulating chilled water may be provided on the surface or side of the laser-transparent member 30. Alternatively, instead of circulating chilled water, a solution other than chilled water, such as an alcohol-based solution, may be circulated. Furthermore, instead of cooling the laser-transparent member 30 with a liquid such as chilled water, a configuration may be provided with a heat dissipation fan or cooling fins, and these may be operated to cool the laser-transparent member 30 using air as a coolant.

[0017] (B2) In this embodiment, pressure P is actively applied to the thermoplastic member 20, but this disclosure may be omitted. For example, the thermoplastic member 20 may be pressed against by the weight of the laser-transparent member 30.

[0018] This disclosure is not limited to the embodiments described above, and can be implemented in various configurations without departing from its spirit. For example, the technical features in the embodiments corresponding to the technical features in each form described in the summary of the invention can be replaced or combined as appropriate in order to solve some or all of the above-described problems, or to achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate. [Explanation of Symbols]

[0019] 10...Member to be joined, 20...Thermoplastic member, 30...Laser-transmitting member, 35...Self-cooling mechanism, B...Substrate, H...Aperture, L...Laser, P...Pressure

Claims

[Claim 1] A laser bonding method for bonding a thermoplastic member and a member to be bonded by laser irradiation, A step of pressing a laser-transparent member having a self-cooling mechanism against the thermoplastic member placed on the member to be joined, A laser bonding method comprising the step of irradiating a thermoplastic member, in a state in which the laser-transparent member is pressed against the thermoplastic member, with a laser through the laser-transparent member in a state in which the cooling function of the self-cooling mechanism is being exerted.

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