Evaluation method, manufacturing method of welded matter, evaluation device and welded matter manufacturing device

Abstract

To provide an evaluation method and the like capable of enhancing imaging quality in the evaluation using imaging of a joint part by laser welding.SOLUTION: An evaluation method evaluates a joint part 130 between a first member 110 and a second member 120 welded by laser beam. The evaluation method includes: radiating illumination light 100 to an evaluation object 190 including the first member 110 and the second member 120 so that the illumination light 100 including the component in a first wavelength range is radiated to the joint part 130 through the first member 110; and imaging by using the component in the first wavelength range in reflection light 101 by the evaluation object 190 of the illumination light 100. The first member 110 includes first resin. The first wavelength range is in a range of equal to or greater than 850 nanometers and equal to or less than 2200 nanometers, and includes wavelengths other than a resonance absorption band of the first resin in the range of equal to or greater than 1500 nanometers and equal to or less than 2200 nanometers.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an evaluation method for welding two members together using laser light, a method for manufacturing a welded product, an evaluation device, and a welded product manufacturing device. [Background technology]

[0002] Laser welding is a welding processing technique in which two components are joined by welding them with laser light.

[0003] One known method of laser welding is to overlap a first member and a second member and irradiate the second member with laser light through the first member. In this method, a joint is formed on the back side of the first member (i.e., the side opposite to the side irradiated with the laser light).

[0004] In addition, in the evaluation of a joint formed by laser welding, for example, a destructive test is performed, such as a method of exposing the joint by cutting and observing it, or a method of measuring the breaking strength by a tensile test.

[0005] As a method for evaluating a joint other than these destructive tests, for example, Patent Documents 1 and 2 disclose a method in which a laser beam or the like is irradiated onto the joint and an image of the reflected or scattered light of the irradiated light is captured.

[0006] Patent Document 1 discloses the use of illumination light emitted from a ring-shaped light source that has passed through a bandpass filter of the same wavelength as the laser light used for welding.

[0007] Patent Document 2 discloses an example in which laser light with a wavelength of 808 nanometers is irradiated. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 4124358 [Patent Document 2] JP 2007-230239 A Summary of the Invention [Problem to be solved by the invention]

[0009] The above-mentioned destructive testing cannot be used to inspect all parts, so it is effective to perform a non-destructive evaluation by, for example, imaging the joints.

[0010] In addition, the tensile test method can only measure the strength of the joint as a whole, and cannot detect defects where a joint is not formed in a part of a ring-shaped joint. For example, when forming an airtight joint, if a part of the joint is not formed or the width of the joint is narrower than the desired width, the joint is defective. Therefore, a method that can evaluate the joint with high accuracy non-destructively is required, for example, a method that can evaluate the width of the joint by improving the image quality.

[0011] Therefore, the present disclosure provides an evaluation method etc. that can improve the imaging quality in evaluations that use imaging of joints formed by laser welding. [Means for solving the problem]

[0012] An evaluation method according to one embodiment of the present disclosure is a method for evaluating a joint between a first member and a second member welded with laser light, the method including: irradiating an evaluation object including a first member and a second member with first light, such that the first light including a component in a first wavelength range is irradiated to the joint through the first member; and imaging a component in the first wavelength range of the first light reflected by the evaluation object, wherein the first member includes a first resin, and the first wavelength range is within a range of 850 nanometers or more and 2200 nanometers or less, and includes wavelengths other than the resonance absorption band of the first resin in a range of 1500 nanometers or more and 2200 nanometers or less.

[0013] A method for manufacturing a weld according to one aspect of the present disclosure is a method for manufacturing a weld in which the first member and the second member are welded together by the laser light, the method including: forming the joint in which the first member and the second member are welded together by irradiating the laser light to the second member through the first member; and evaluating the joint using the evaluation method described above.

[0014] An evaluation device according to one embodiment of the present disclosure is an evaluation device for evaluating a joint between a first member and a second member welded with laser light, and includes: an illumination device that irradiates an evaluation object including a first member and a second member with first light, such that the first light including a component in a first wavelength range is irradiated to the joint through the first member; and an imaging device that captures an image using a component in the first wavelength range in the light of the first light reflected by the evaluation object, wherein the first member includes a first resin, and the first wavelength range is within a range of 850 nanometers or more and 2200 nanometers or less, and includes wavelengths other than the resonance absorption band of the first resin in the range of 1500 nanometers or more and 2200 nanometers or less.

[0015] A welded product manufacturing apparatus according to one embodiment of the present disclosure includes a laser irradiation device that irradiates the laser light through the first member to the second member to form the joint by welding the first member and the second member, and the evaluation device. Effect of the Invention

[0016] According to the present disclosure, it is possible to improve the imaging quality in evaluation using imaging of a joint formed by laser welding. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a diagram showing a configuration of an evaluation device according to the first embodiment. [Diagram 2] FIG. 2 is a diagram for explaining the wavelength range used for imaging. [Diagram 3]FIG. 3 is a diagram showing the damping coefficient of resin. [Figure 4] FIG. 4 is a flowchart showing an example of an evaluation method using the evaluation device according to the first embodiment. [Figure 5A] FIG. 5A is a diagram showing an example of an image of a joint. [Figure 5B] FIG. 5B is a diagram showing another example of an image of a joint. [Figure 5C] FIG. 5C is a diagram showing yet another example of an image of a joint. [Figure 6] FIG. 6 is an exploded perspective view showing the shape of the evaluation object used in the evaluation. [Figure 7] FIG. 7 is a diagram for comparing the imaging results of an evaluation object imaged with illumination light of different wavelengths. [Figure 8] FIG. 8 is a diagram showing the damping coefficient of the first member. [Figure 9A] FIG. 9A is a diagram for explaining the positional relationship between the illumination device and the imaging device. [Figure 9B] FIG. 9B is a diagram for comparing imaging results of an evaluation object imaged by changing the positional relationship between the lighting device and the imaging device. [Figure 10] FIG. 10 is a conceptual diagram for explaining the path of illumination light irradiated onto the evaluation object. [Figure 11] FIG. 11 is a diagram showing the configuration of a welded product manufacturing apparatus according to the second embodiment. [Figure 12] FIG. 12 is a flowchart showing an example of a method for producing a weld using the weld production apparatus according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] (How one aspect of the present disclosure was achieved) As described above, when evaluating a joint formed by laser welding by imaging, there is a demand for improving the imaging quality. The present inventors have found that the following problems arise in the conventional method of evaluating a joint formed by laser welding by imaging.

[0019] In laser welding, the first member through which the laser beam passes generally contains a resin. The resin may be crystalline. In addition, the first member may contain fillers such as glass fiber, carbon fiber, and talc in addition to the resin to improve its functionality.

[0020] When the resin contained in the first member is crystalline or when a filler is mixed in, the transmittance of visible light is usually low. Therefore, it is difficult to observe the joint formed on the back side of the first member using visible light. More specifically, when the resin of the first member is crystalline or when a filler is mixed in the first member, visible light does not reach the joint sufficiently, or the scattering of visible light drowns out the spatial information of the joint, making it difficult to image the joint using conventional methods.

[0021] Furthermore, even when infrared light is used for imaging, some wavelengths are subject to large scattering or absorption, making it impossible to improve the quality of imaging of the joint.

[0022] As described above, the present inventors have found that when evaluating a joint formed by laser welding by imaging, it may be difficult to improve the imaging quality depending on the wavelength of light used to evaluate the joint.

[0023] In view of the above problems, the present disclosure provides an evaluation method and the like that can improve the imaging quality in evaluations that use imaging of joints formed by laser welding.

[0024] An outline of one aspect of the present disclosure is as follows.

[0025] An evaluation method according to one embodiment of the present disclosure is a method for evaluating a joint between a first member and a second member welded with laser light, the method including: irradiating an evaluation object including a first member and a second member with first light, such that the first light including a component in a first wavelength range is irradiated to the joint through the first member; and imaging using the component in the first wavelength range of the first light reflected by the evaluation object, wherein the first member includes a first resin, and the first wavelength range is within a range of 850 nanometers or more and 2200 nanometers or less, and includes wavelengths other than the resonance absorption band of the first resin in the range of 1500 nanometers or more and 2200 nanometers or less.

[0026] As a result, the first light containing a component in a first wavelength range that is unlikely to be scattered or absorbed by the first member is irradiated onto the evaluation object, so that the first light passes through the first member and easily reaches the joint. Therefore, by capturing an image using the component in the first wavelength range of the reflected light of the first light from the region including the joint, an image that clearly shows the joint can be obtained. Therefore, the evaluation method according to the present embodiment can improve the image quality in evaluation using an image of the joint by laser welding.

[0027] Furthermore, for example, the first light may be incoherent light.

[0028] This makes it possible to suppress uneven illumination called speckle, which tends to occur with highly coherent light sources, thereby further improving imaging quality.

[0029] Furthermore, for example, the first light may have a component with a wavelength of less than 850 nanometers of 50% or less.

[0030] This reduces the amount of components in the first light with wavelengths below 850 nanometers, which tend to scatter and obscure the image of the joint, making it possible to obtain an image that shows the joint more clearly.

[0031] Furthermore, for example, the direction in which the first light is specularly reflected by the surface of the first member does not have to coincide with the imaging direction in which the reflected light is imaged.

[0032] A part of the first light is specularly reflected on the surface of the first member, but the direction of specular reflection does not coincide with the imaging direction, so the specularly reflected light component in the reflected light of the first light to be imaged is reduced. Since the specularly reflected light does not reach the joint, the reduction in the specularly reflected light component in the imaged reflected light makes it possible to obtain an image in which the joint is more clearly shown.

[0033] Also, for example, the first light may have a component in the first wavelength range of more than 50%.

[0034] This increases the amount of components in the first wavelength range in the first light, making it possible to obtain an image in which the joint is more clearly visible.

[0035] Also, for example, the first wavelength range may be within the range of 1050 nanometers to 2200 nanometers.

[0036] This makes it even more difficult for the first light to be absorbed and scattered within the first member, making it possible to obtain an image that shows the joint more clearly.

[0037] Also, for example, among the components in the first wavelength range contained in the first light, components having wavelengths other than the resonance absorption band may be more numerous than components having wavelengths in the resonance absorption band.

[0038] This increases the amount of components of the first light that are not absorbed by resonance absorption in the first resin, thereby making it possible to further improve imaging quality.

[0039] Furthermore, a method for manufacturing a weld according to one embodiment of the present disclosure is a method for manufacturing a weld in which the first member and the second member are welded together by the laser light, the method including: forming the joint in which the first member and the second member are welded together by irradiating the laser light to the second member through the first member; and evaluating the joint using the evaluation method described above.

[0040] As a result, when a welded product is produced by welding a first member and a second member, the bonded portion can be evaluated using the above-described evaluation method with improved imaging quality of the bonded portion.

[0041] Also, for example, the method for manufacturing the welded product may further include repairing the bonded portion based on a result of evaluating the bonded portion.

[0042] This allows the joint to be repaired even if a joint is defective, reducing the occurrence of defective products.

[0043] Moreover, an evaluation device according to one aspect of the present disclosure is an evaluation device for evaluating a joint between a first member and a second member welded with laser light, the evaluation device including: an illumination device that irradiates an evaluation object including a first member and a second member with first light, such that the first light including a component in a first wavelength range is irradiated to the joint through the first member; and an imaging device that captures an image using a component in the first wavelength range in the light of the first light reflected by the evaluation object, wherein the first member includes a first resin, and the first wavelength range is within a range of 850 nanometers or more and 2200 nanometers or less, and includes wavelengths other than the resonance absorption band of the first resin in the range of 1500 nanometers or more and 2200 nanometers or less.

[0044] As a result, similarly to the above-described evaluation method, an image in which the joint is clearly visible can be obtained. Therefore, the evaluation device according to the present embodiment can improve the image capturing quality in evaluation using an image of the joint formed by laser welding.

[0045] Furthermore, for example, the lighting device and the imaging device may be positioned such that the direction in which the first light is emitted by the lighting device and specularly reflected by the surface of the first member does not coincide with the imaging direction in which the reflected light is imaged by the imaging device.

[0046] This reduces the component of light that is specularly reflected by the first member from the reflected light being captured, making it possible to obtain an image that more clearly shows the joint.

[0047] In addition, a welded product manufacturing apparatus according to one embodiment of the present disclosure includes a laser irradiation device that forms the joint by welding the first member and the second member by irradiating the laser light to the second member through the first member, and the evaluation device.

[0048] This makes it possible to realize a welded product manufacturing apparatus that can evaluate a joint when welding a first member and a second member using the above-mentioned evaluation device with improved imaging quality of the joint.

[0049] Hereinafter, embodiments will be described with reference to the drawings.

[0050] The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, components, arrangement and connection of components, steps, and order of steps shown in the following embodiments are merely examples and are not intended to limit the present disclosure. In addition, among the components in the following embodiments, components that are not described in the independent claims are described as optional components. In addition, each figure is not necessarily a strict illustration. Therefore, for example, the scales in each figure do not necessarily match. In addition, in each figure, substantially the same configuration is given the same symbol, and duplicated explanations may be omitted or simplified.

[0051] Furthermore, in this specification, terms indicating relationships between elements, terms indicating the shapes of elements, and numerical ranges are not expressions that only express a strict meaning, but are expressions that include a substantially equivalent range, for example, a difference of about a few percent.

[0052] In addition, in this specification, the term "light" includes not only general visible light, but also electromagnetic waves in general, such as near infrared rays, mid infrared rays, far infrared rays, and ultraviolet rays.

[0053] (Embodiment 1) First, in the first embodiment, an evaluation device capable of improving the image capturing quality in evaluation using images of joints formed by laser welding will be described.

[0054] [Overall configuration of evaluation device] First, the overall configuration of an evaluation device for a joint formed by laser welding according to the present embodiment will be described. Fig. 1 is a diagram showing the configuration of the evaluation device according to the present embodiment.

[0055] As shown in FIG. 1, the evaluation device 170 includes an illumination device 150 and an imaging device 160. The evaluation device 170 may also include a control device 140 and a light-shielding housing 180 for blocking ambient light. The illumination device 150 and the imaging device 160 operate, for example, based on the control of the control device 140 or the operation of a user. Although not shown, the evaluation device 170 may also include a stage for fixing the evaluation object 190 or for adjusting the position or angle of the evaluation object 190. The evaluation device 170 may also include a display device for displaying the imaging result of the imaging device 160.

[0056] The evaluation device 170 is a device for evaluating a joint 130 between a first member 110 and a second member 120 of an evaluation object 190 including the first member 110 and the second member 120 welded by laser light. The evaluation object 190 is a weld formed by welding the first member 110 and the second member 120 by laser light. The first member 110 is a member that transmits the laser light for welding more easily than the second member 120, and the second member 120 is a member that absorbs the laser light for welding more easily than the first member 110. The joint 130 is formed by irradiating the second member 120 with a laser light through the first member 110. Specifically, second member 120 generates heat by absorbing the laser light that has passed through first member 110, and this heat causes first member 110 and second member 120 to melt and mix together. When the laser light is stopped, the members cool and the molten part solidifies, forming a welded joint 130.

[0057] The first member 110 includes a first resin. The first resin is, for example, a resin having thermoplasticity. The type of the first resin is not particularly limited as long as it is a resin that can be laser welded.

[0058] In this embodiment, even if the first member 110 is a member that easily absorbs or scatters light, the imaging quality in evaluating the bonded portion 130 can be improved. For example, the first resin may be a crystalline resin. The first member 110 may contain at least one of a filler and a dye.

[0059] The second member 120 includes a second resin. The second resin is, for example, a resin having thermoplasticity. The type of the second resin is not particularly limited as long as it is a resin that can be laser welded. The first resin and the second resin are, for example, the same type of resin, but may be different types of resin.

[0060] In the evaluation device 170 according to the present embodiment, the lighting device 150 irradiates the evaluation object 190 with illumination light 100, which is an example of a first light, from the first member 110 side to the joint 130 with the second member 120. In other words, the lighting device 150 irradiates the evaluation object 190 with the illumination light 100 such that the illumination light 100 is irradiated to the joint 130 through the first member 110.

[0061] The imaging device 160 captures an image of the reflected light 101 of the illumination light 100 by the evaluation object 190. In this way, the imaging device 160 captures an image of a range including the joint 130 of the evaluation object 190.

[0062] The control device 140, for example, controls the operations of the illumination device 150 and the imaging device 160, and performs various information processing related to the images acquired by the imaging device 160. In addition, when the evaluation device 170 includes a display device and a movable stage, the control device 140 may control these. The control device 140 is realized, for example, by a processor and a memory. For example, a program for executing the processing is stored in the memory. The control device 140 is, for example, a computer.

[0063] The light-shielding housing 180 blocks ambient light so that it does not enter the imaging device 160. The light-shielding housing 180 is, for example, a box-shaped member made of metal or resin. The ambient light is, for example, in some cases, light that illuminates the room in which the evaluation device 170 is placed, and in other cases, sunlight that enters through a window or the like in the room in which the evaluation device 170 is placed.

[0064] The present embodiment is characterized by the wavelength range in which imaging is performed. More specifically, the evaluation device is characterized by taking into consideration a wavelength range that is preferable for imaging and a wavelength range that is not preferable for imaging. The wavelength range of light to be imaged, such as a wavelength range that is preferable for imaging and a wavelength range that is not preferable for imaging, will be described later.

[0065] First, each component of the evaluation device 170 will be described in detail below.

[0066] [Lighting equipment] The illumination device 150 includes a light source 151 that generates light that becomes the illumination light 100, and an illumination optical system 152 that guides the illumination light 100 to an evaluation object 190 and irradiates the object with the illumination light 100.

[0067] As described below, the illumination light 100 includes components in a wavelength range preferred for imaging. The illumination light 100 includes, for example, components in a first wavelength range that is at least a part of the wavelength range preferred for imaging. The illumination light 100 does not need to include all wavelength components in the wavelength range preferred for imaging, and may include only components in a part of the wavelength range.

[0068] The light source 151 is a light source that emits light with a limited wavelength range, such as a light emitting diode, a laser, and a superluminescent diode. The light source 151 may also be a light source that emits components in a wide wavelength range, such as a halogen lamp and a xenon lamp. Among these, the light source 151 may be a light source that emits incoherent light, such as a light emitting diode. In other words, the illumination light 100 may be incoherent light. This makes it possible to suppress uneven illuminance, called speckle, which is likely to occur when a highly coherent light source such as a laser is used, and further improves the imaging quality.

[0069] The light source 151 may simultaneously emit light having wavelength components other than the wavelength range preferred for imaging. In other words, the illumination light 100 may include components other than the wavelength range preferred for imaging.

[0070] The illumination optical system 152 is an optical system for irradiating the illumination light 100 emitted by the light source 151 to a predetermined position on the evaluation object 190 from a predetermined direction. The illumination optical system 152 is disposed, for example, on the light emission side of the light source 151, and guides the illumination light 100 to the evaluation object 190. The illumination optical system 152 can be configured using lenses, mirrors, and the like. The illumination optical system 152 may be configured with a plurality of elements. Note that, when the light source 151 is a light source whose light emission direction is controlled to some extent, such as a bullet-shaped LED, the illumination optical system 152 may be omitted. Also, the light source 151 and the illumination optical system 152 may be integrated, such as when the light source 151 is a lamp with a reflector.

[0071] The illumination optical system 152 may include a shutter or the like for stopping the irradiation of light when necessary. The illumination optical system 152 may also include a mechanism for adjusting the amount of light. The mechanism for adjusting the amount of light may be an aperture or a neutral density filter, or an electric circuit for controlling the amount of current or applied voltage to the light source 151.

[0072] The illumination device 150 may further include an optical filter 153 that reduces components other than those in a wavelength range preferred for imaging, for example, components in a wavelength range unpreferable for imaging, from the light emitted by the light source 151. The optical filter 153 may be, for example, a band-pass filter or a long-pass filter. These filters may be made of colored glass or colored resin, a dielectric multilayer film, or a semiconductor substrate. Note that "colored" means that the filter has a transmission wavelength dependency, and does not mean that it is colored with the color of visible light.

[0073] [Imaging device] The imaging device 160 captures an image of an evaluation object 190 using the illumination light 100. The imaging device includes an imaging element 161 and an imaging optical system 162.

[0074] The imaging device 160 captures an image of a region including the joint 130 of the evaluation object 190 by using components in a first wavelength range among components contained in the reflected light 101 of the illumination light 100.

[0075] The image sensor 161 has sensitivity to at least a part of the first wavelength range. The image sensor 161 does not have to have sensitivity to the entire wavelength range of the first wavelength range.

[0076] The imaging element 161 may be sensitive to a wavelength range other than the first wavelength range, or may be sensitive to light in a wavelength range that is not preferable for imaging.

[0077] The imaging element 161 can be constructed using a photoelectric conversion element that uses, for example, single crystal silicon, black silicon in which a fine structure is formed on the surface of single crystal silicon, an InGaAs epitaxial thin film, quantum dots such as PbS or PbSe, or semiconductor carbon nanotubes as a photoelectric conversion material.

[0078] The wavelength range to which the imaging element 161 has high sensitivity varies depending on the type of photoelectric conversion material used in the imaging element 161. The wavelength range to which the imaging element 161 has high sensitivity also varies depending on the size of the quantum dots and the chirality of the semiconducting carbon nanotubes used in the imaging element 161. For example, a photoelectric conversion material used in the imaging element 161 is selected so as to have high sensitivity in a first wavelength range.

[0079] For example, if the first wavelength range includes wavelengths from about 1000 nanometers to about 1100 nanometers, the image sensor 161 can be realized with high sensitivity to the first wavelength range by using black silicon or InGaAs as the photoelectric conversion material. Also, if the first wavelength range includes wavelengths around 1450 nanometers, the image sensor 161 can be realized with high sensitivity to the first wavelength range by using InGaAs, PbSe quantum dots, PbS quantum dots, or the like as the photoelectric conversion material.

[0080] The imaging device 160 may further include an optical filter 163 for blocking or significantly attenuating light in a wavelength range unfavorable for imaging. This makes it possible to improve imaging quality even when the imaging element 161 has sensitivity to a wavelength range other than the first wavelength range and the illumination light 100 and / or light such as ambient light irradiated on the evaluation object 190 other than the illumination light 100 contains components in a wavelength range unfavorable for imaging.

[0081] The imaging optical system 162 has a function of forming an image of a range including the joint 130 of the evaluation object 190 on the imaging element 161. The imaging optical system 162 can be composed of, for example, a lens made of glass or plastic, or a curved mirror.

[0082] The imaging optical system 162 may include mechanisms such as a shutter and / or an aperture, if necessary.

[0083] The optical filter 163 may be, for example, a band-pass filter, a short-pass filter, or a long-pass filter, etc. These filters may be made of colored glass or colored resin, a dielectric multilayer film, or a semiconductor substrate.

[0084] [Relative positional relationship between the lighting device and the imaging device] Here, the arrangement of the lighting device 150, the imaging device 160, and the evaluation object 190 will be described. The relative positional relationship between the lighting device 150, the imaging device 160, and the evaluation object 190 is, for example, such that the regular reflection light of the illumination light 100 from the lighting device 150 by the surface of the first member 110 of the evaluation object 190, particularly the surface of the first member 110 near the area where the joint 130 exists, is unlikely to directly enter the imaging device 160. For example, in the evaluation device 170, the lighting device 150 and the imaging device 160 are arranged so that the direction of the irradiation direction of the illumination light 100 from the lighting device 150, which is specularly reflected by the surface of the first member 110 of the evaluation object 190, does not coincide with the imaging direction in which the reflected light 101 is imaged by the imaging device 160. The irradiation direction is, for example, the direction of the optical axis of the illumination light 100 irradiated by the lighting device 150. The imaging direction is, for example, the direction that is the center of the angle of view of the imaging device 160.

[0085] For example, when the imaging device 160 is positioned so that the imaging direction of the imaging device 160 is perpendicular to the surface of the first component 110 of the object to be evaluated 190, the lighting device 150 is positioned so as to irradiate the illumination light 100 from a direction inclined with respect to the direction perpendicular to the surface of the first component 110 of the object to be evaluated 190.

[0086] The evaluation device 170 may have a mechanism for changing the relative positional relationship between the lighting device 150 and the imaging device 160 depending on the shape of the evaluation object 190. For example, at least one of the lighting device 150 and the imaging device 160 may be movable, and the evaluation device 170 may have a mechanism for changing the position of at least one of the lighting device 150 and the imaging device 160 depending on the shape of the evaluation object 190. The mechanism is constituted by, for example, a driving device such as an actuator or a motor.

[0087] Furthermore, for example, the evaluation device 170 may include at least a plurality of lighting devices 150 and imaging devices 160. In this case, for example, depending on the shape of the evaluation target object 190, the lighting device 150 that actually irradiates the illumination light 100 is selected and used. Furthermore, for example, a plurality of imaging results (images) by a plurality of imaging devices 160 may be presented, or a mechanism for selecting an appropriate one from the plurality of imaging results may be provided. These operations such as selection may be performed by the user, or may be performed based on the control of the control device 140.

[0088] Furthermore, for example, the evaluation device 170 may include, as the above-mentioned stage, a stage for adjusting the position or angle of the evaluation object 190. The stage has a mechanism capable of adjusting the position or angle of the evaluation object 190 so as to satisfy the above-mentioned relative positional relationship according to the shape of the evaluation object 190, based on the control of the user or the control device 140.

[0089] [Wavelength range for imaging] As described above, the present embodiment is characterized by the wavelength range of light used to image the joint 130.

[0090] The present inventors conducted experiments and studies on the light transmission characteristics of resin, and came to the conclusion that imaging quality can be improved by imaging the bonded portion 130 using light in a wavelength range having the following characteristics, that is, a first wavelength range which is at least a part of the wavelength range preferred for imaging in this specification. FIG. 2 is a diagram for explaining the wavelength range used for imaging. Note that the first wavelength range 201 shown in FIG. 2 is an example, and is not limited to the range shown in FIG. 2, and may be set as long as it is a wavelength range that satisfies the following conditions.

[0091] First, the first wavelength range 201 includes a component included in the second wavelength range 202 .

[0092] The second wavelength range 202 is a wavelength range of 850 nanometers or more and 2200 nanometers or less. Therefore, the first wavelength range 201 is within a wavelength range of 850 nanometers or more and 2200 nanometers or less. The second wavelength range 202 is a wavelength range in which absorption and scattering do not occur significantly in the first member 110. In addition, from the viewpoint of further reducing absorption and scattering in the first member 110 and improving imaging quality, the first wavelength range 201 may be within a wavelength range of 1050 nanometers or more and 2200 nanometers or less.

[0093] Secondly, the first wavelength range 201 includes a wavelength range other than the wavelengths belonging to the resonance absorption band 210 of the first resin included in the first member 110 in the wavelength range of 1500 nanometers or more and 2200 nanometers or less. The first wavelength range does not have to include the wavelengths of the resonance absorption band 210 of the first resin in the wavelength range of 1500 nanometers or more and 2200 nanometers or less. Note that, although there is one resonance absorption band 210 of the first resin in the wavelength range of 1500 nanometers or more and 2200 nanometers or less in the example shown in FIG. 2, there may be more than one.

[0094] The resonance absorption band is a wavelength band in which the first resin exhibits significant light absorption. The position and range of the resonance absorption band 210 differ depending on the resin, but the inventors have experimentally confirmed that many of the resins used in the laser welding process have a relatively strong resonance absorption band 210 in the wavelength range of 1500 nanometers or more and 2200 nanometers or less.

[0095] FIG. 3 is a diagram showing the attenuation coefficient of resin. FIG. 3 shows the results of measurements made by the inventor on the attenuation coefficient in transmission through thin plates of polyethylene (PE), polypropylene (PP) and polybutylene terephthalate (PBT). The horizontal axis of FIG. 3 is the wavelength, and the vertical axis of FIG. 3 is the attenuation coefficient. Here, the attenuation coefficient indicates the proportion of light that does not reach the detector placed behind a thin plate when light is irradiated perpendicularly to the plate. When the attenuation coefficient is 0, it means that the light is not scattered or absorbed at all, and each increase of 1 in the attenuation coefficient value means that the amount of transmitted light is reduced to 1 / 10 due to the effects of scattering or absorption.

[0096] There are two factors that cause light attenuation by resin: one is absorption by the resin, and the other is scattering by the resin.

[0097] The attenuation coefficient of the resin exhibits wavelength dependency as shown in Figure 3. Among the wavelength dependencies, the factor that causes monotonous attenuation as the wavelength becomes longer is scattering by the resin.

[0098] On the other hand, although the positions differ for each resin, peaks where the attenuation coefficient is large at specific wavelengths can be seen for each resin at the positions indicated by the arrows in Figure 3. These peaks are due to resonance absorption by the resin.

[0099] The arrow line 211 indicates the range (so-called half-width) of the attenuation coefficient in resonance absorption, which is halfway from the baseline (e.g., the two-dot chain line in FIG. 3) to the peak, and is shown as a guide for the range where the effect of resonance absorption is strong. In this specification, the resonance absorption band 210 means the wavelengths in the range of the half-width of the resonance absorption peak.

[0100] When light having a wavelength belonging to the resonance absorption band 210 is irradiated, resonance absorption occurs in the resin, and the transmitted component is significantly reduced. Therefore, if illumination light having only wavelength components belonging to the resonance absorption band 210 is used, it becomes difficult to deliver sufficient light to the bonding part 130 present on the back side of the first member 110 and obtain a clear image of the bonding part 130.

[0101] Therefore, it is not preferable to perform imaging using only light of wavelengths belonging to this resonance absorption band 210.

[0102] Note that even if the illumination light 100 contains wavelength components belonging to the resonance absorption band 210, scattering that reduces image clarity does not occur significantly. Therefore, the illumination light 100 may contain wavelength components belonging to the resonance absorption band 210. From the viewpoint of improving imaging quality, the components in the first wavelength range contained in the illumination light 100 other than the resonance absorption band 210 are more numerous than the wavelength components in the resonance absorption band 210, for example.

[0103] Furthermore, the resonance absorption of the resin also exists in wavelengths other than the wavelength range of 1500 nanometers or more and 2200 nanometers or less in which the resonance absorption band 210 exists.

[0104] As for resonance absorption outside the wavelength range of 1500 nanometers or more and 2200 nanometers or less, firstly, most resins show resonance absorption in the wavelength range of wavelengths greater than 2200 nanometers. This resonance absorption is stronger than the resonance absorption in the wavelength range of 1500 nanometers or more and 2200 nanometers or less. Therefore, light in the wavelength range greater than 2200 nanometers is also not suitable for the illumination light 100. However, light in this wavelength range is also basically unlikely to cause scattering that reduces the clarity of the image. Therefore, components in the wavelength band 220 greater than wavelength 2200 nanometers may be included in the illumination light 100.

[0105] Secondly, most resins also exhibit resonance absorption in the wavelength range of 1000 nanometers or more and less than 1500 nanometers as a resonant absorption outside the wavelength range of 1500 nanometers or more and 2200 nanometers or less. However, this resonance absorption is weaker than the resonance absorption in the wavelength range of 1500 nanometers or more and 2200 nanometers or less. Therefore, if the thickness of the first member 110 used in a general laser welding process is about the same, it often has a transparency that allows observation of the joint 130. Therefore, it is possible to use the illumination light 100 that has only light components in the wavelength range that overlaps with the resonance absorption in this range.

[0106] Furthermore, the present inventors have discovered that, contrary to the wavelength ranges preferable for imaging, it is not preferable to use light in the following third wavelength range for imaging.

[0107] The third wavelength range 203 is a range of wavelengths less than 850 nanometers. The light in the third wavelength range 203 is likely to be scattered in a member containing a crystalline resin and a filler, even if the light has a near-infrared wavelength. When the first member 110 contains a crystalline resin and when the first member 110 contains a filler, the light in the third wavelength range 203 is scattered a lot in the first member 110. Therefore, it is difficult to obtain a clear image of the joint 130 on the back side of the first member 110 by using only the third wavelength range 203.

[0108] Furthermore, when the imaging results include both light in a wavelength range that is favorable for imaging (first wavelength range) and light in a wavelength range that is unfavorable for imaging (third wavelength range), the image of the joint 130 becomes unclear due to scattering as the proportion of the latter increases.

[0109] From the viewpoint of improving the clarity of the imaging result, the illumination light 100 may have a third wavelength range component of 50% or less, or may have a component of the first wavelength range of 50% or less. The proportion of a component in a certain wavelength range in the illumination light 100 is the proportion of the integrated emission intensity at wavelengths in the certain wavelength range to the integrated emission intensity over the entire wavelength range in the emission spectrum of the illumination light 100.

[0110] In order to improve the clarity of the imaging result, the proportion of the imaging result by the imaging device 160 due to light in the first wavelength range 201, which is preferable for imaging, may be 50% or more, or may be 90% or more. In addition, the proportion of the imaging result by the imaging device 160 due to light in the third wavelength range 203, which is not preferable for imaging, may be 50% or less, or may be 10% or less.

[0111] Here, the ratio of light in a certain wavelength range to the imaging result is defined as follows.

[0112] The imaging device 160 has an imaging element 161 that integrates photoelectric conversion elements that convert light into an electrical signal. When light is incident on each photoelectric conversion element, it generates a signal charge according to the amount of photons. The signal charge is accumulated over a period of time called the exposure time, and the total amount of accumulated signal charge is measured.

[0113] In this specification, the proportion of signal charges generated by light in a certain wavelength range out of the total amount of accumulated signal charges is defined as the proportion of the imaging result that is accounted for by light in a certain wavelength range.

[0114] The amount of signal charge generated by light in a certain wavelength range is proportional to the intensity of the component in the certain wavelength range contained in the reflected light 101 of the illumination light 100 by the evaluation target object 190, and to the ratio at which the imaging element converts photons into signal charge in a certain wavelength range, that is, the so-called quantum efficiency. If the light collection efficiency and transmittance of the imaging optical system 162 are wavelength-dependent, the amount of signal charge generated by light in a certain wavelength range is also proportional to these values. If the imaging device 160 includes an optical filter 163 whose transmittance is wavelength-dependent, the amount of signal charge also depends on the transmittance of the filter.

[0115] The following methods can be used to increase the proportion of the imaging result caused by light in the first wavelength range 201, which is preferable for imaging, or to decrease the proportion of the imaging result caused by light in the third wavelength range 203, which is unpreferable for imaging.

[0116] The first method is to use a light source 151 in which the proportion of components belonging to a first wavelength range 201 is high or the proportion of components belonging to a third wavelength range 203 is low in the light emitted by the light source 151 .

[0117] For example, by selecting as the light source 151 a light emitting diode or a superluminescent diode that has the characteristic of emitting light in a narrow wavelength range and making that wavelength range fall within the first wavelength range 201, it is possible to increase the proportion of the components in the first wavelength range 201 in the imaging result and decrease the proportion of the components in the third wavelength range 203.

[0118] The wavelength range of this light source 151 can be selected independently of the wavelength of the laser light used for welding. For example, the central wavelength of the light emitted by the light source 151 may be different from the wavelength of the laser light used for welding. In this case, even when evaluation is performed in a state where the laser light is irradiated, the influence of the laser light can be reduced.

[0119] In the second method, the illumination device 150 includes an optical filter 153 that transmits light in the first wavelength range 201 and attenuates light in the third wavelength range 203 .

[0120] The optical filter 153 may be, for example, a long-pass filter having a first wavelength range 201 as a transmission range and a third wavelength range 203 as a cut-off range. By using a long-pass filter, it is possible to efficiently illuminate the evaluation object 190 by transmitting a wide range of wavelengths longer than the cut-off range while attenuating light in the third wavelength range 203, thereby improving the imaging quality.

[0121] The optical filter 153 does not need to have good transmittance over the entire first wavelength range. For example, when the light source 151 emits the illumination light 100 having components only in a limited wavelength range, such as a light emitting diode, the optical filter 153 may be a bandpass filter having good transmittance over a part or the entire wavelength range of the components of the illumination light 100.

[0122] The third method is a method in which the imaging device 160 is configured to include an optical filter 163 that attenuates light in the third wavelength range 203. The characteristics required for the optical filter 163 are approximately the same as the characteristics required for the optical filter 153. However, when the evaluation target object 190 is illuminated by environmental light other than the illumination light 100 and the environmental light contains components in the third wavelength range 203, it is preferable that the optical filter 163 has a capability of blocking the components in the third wavelength range 203 contained in the environmental light.

[0123] The fourth method is to use, as the imaging element 161 of the imaging device 160, an element that has high quantum efficiency in the first wavelength range 201 and low quantum efficiency in the third wavelength range 203. For example, in the case of an imaging element 161 that uses InGaAs as a photoelectric conversion material, there is an imaging element that has no sensitivity in the third wavelength range 203, which is less than 850 nanometers.

[0124] Another method is to configure the evaluation device 170 with a mechanism for stopping the illumination during the period when the evaluation of the joint 130 is performed when the ambient light is lighting for visually checking the evaluation object 190.

[0125] These methods may be used alone or in combination.

[0126] [Operation of evaluation device] Next, an example of the operation of the evaluation device 170 according to the present embodiment will be described. Specifically, a method of evaluating the joint 130 performed using the evaluation device 170 will be described. Fig. 4 is a flowchart showing an example of the evaluation method using the evaluation device 170 according to the present embodiment.

[0127] 4, first, as a preparation step, the evaluation object 190 is placed at a position where the imaging device 160 can capture an image (step S11). Specifically, the evaluation object 190 is placed on a stage or the like so that the first member 110 of the evaluation object 190 faces the imaging device 160 and the lighting device 150.

[0128] The evaluation object 190 may be placed on a fixed stage, or may be placed on a movable stage, and the evaluation location may be changed sequentially in the following procedure.

[0129] Next, as an illumination step, the illumination device 150 irradiates the evaluation object 190 with the illumination light 100 so that the illumination light 100 is irradiated to the joint 130 through the first member 110 of the evaluation object 190 (step S12). The illumination device 150 may irradiate the entire joint 130 with the illumination light 100 at once, or may irradiate only a part of the joint 130 with the illumination light 100 and sequentially change the irradiation location. In this case, the user or the control device 140 may change the irradiation position by changing the setting of the illumination optical system 152, for example, the angle of the mirror. In addition, if the evaluation object 190 is placed on a movable stage, the user or the control device 140 may move the stage.

[0130] Next, as an imaging step, the imaging device 160 captures an image using a component in a first wavelength range in the reflected light 101 of the illumination light 100 by the evaluation object 190 (step S13). The imaging device 160 outputs the imaging result (i.e., an image) to the outside or the control device 140. When the evaluation device 170 includes a display device, the control device 140 may cause the display device to display the acquired imaging result.

[0131] If the entire area of ​​the joint 130 to be evaluated can be imaged at once, the process proceeds to the next step. If only a part of the joint 130 can be imaged, such as when the irradiation location is changed sequentially as described above, or when the reflected light 101 from an area including only a part of the joint 130 is imaged, the relative position between the evaluation object 190 and the imaging device 160 and / or the irradiation location is changed, and the imaging device 160 repeats imaging. In other words, step S13, or steps S12 and S13 may be repeated until a desired image is obtained.

[0132] Next, as an evaluation step, the joint 130 is evaluated using the imaging result of capturing the reflected light 101 by the evaluation object 190 (step S14). The output imaging result includes information on the joint 130. From this, for example, the control device 140 or a user may extract a contour from the image that is the imaging result, and evaluate the shape and / or width of the joint 130. The control device 140 may also perform pass / fail judgment using a trained logical model that is machine-learned by linking the imaging result with the strength test result such as a tensile test of the evaluation object 190. The control device 140 may also perform pass / fail judgment based on the features of the imaging result from a trained logical model that links the features of the imaging result with the pass / fail result.

[0133] Furthermore, the control device 140 may determine the width of the joint 130 from the imaging result by image processing or the like, and perform a pass / fail judgment based on the determined width of the joint 130. For example, for an evaluation object 190 that requires airtightness, the control device 140 determines the width of the joint 130 from the imaging result, and performs a pass / fail judgment in which the product is judged to be pass if the minimum width of the joint 130 is equal to or greater than a predetermined value.

[0134] The evaluation of the bonded portion 130 in step S14 may be performed by the user or the like simply checking the imaging results.

[0135] Here, an example of an image of the joint 130 obtained by imaging using the above evaluation method is shown. Figures 5A to 5C are diagrams showing an example of an image of the joint 130. For the first member 110 and the second member 120 for acquiring the images shown in Figures 5A to 5C, flat glass fiber mixed PBT resin was used. Laser light was irradiated through the first member 110 to the second member 120 under three levels of irradiation conditions to prepare evaluation samples of a good product, a defective product due to insufficient welding, and a defective product due to resin deterioration caused by excessive irradiation. Figure 5A shows the imaging result of imaging a good product. Figure 5B shows the imaging result of imaging a defective product due to insufficient welding. Figure 5C shows the imaging result of imaging a defective product due to resin deterioration caused by excessive irradiation. In addition, in acquiring the image, illumination light was irradiated using an LED light source with a central wavelength of 1300 nanometers, and imaging was performed using an imaging element using InGaAs. In Figures 5A to 5C, the area with a darker color than other areas is the joint 130 that was normally welded.

[0136] Since glass fibers are mixed into the first member 110, the three levels of evaluation samples cannot be clearly distinguished from one another when imaged using visible light or when visually inspected, but as shown in Figures 5A to 5C, the image results obtained by the evaluation method according to the present embodiment clearly show the differences in the joints 130. For example, it can be seen that the joints 130 are formed with a uniform width in the non-defective product shown in Figure 5A. In contrast, it can be seen that the width of the joints 130 is non-uniform and discontinuous in the defective product due to insufficient welding shown in Figure 5B.

[0137] The width of the joint 130 has a large effect on the characteristics, such as the airtightness, of the evaluation object 190. In the evaluation method according to the present embodiment, it is possible to measure the width of the joint 130, and a pass / fail judgment may be made based on the width.

[0138] 5C, the image capturing result of the defective product with resin deterioration due to excessive irradiation shows that a white area is generated in the joint 130. In the evaluation method according to the present embodiment, it is also possible to judge the quality of the product based on the characteristics of such an image.

[0139] [Effects, etc.] Next, the effects of the evaluation device and evaluation method according to the present embodiment will be described using actual imaging results. Specifically, the present inventors will describe the results of experiments in which images were captured while changing the lighting conditions and other factors, and their considerations.

[0140] FIG. 6 is an exploded perspective view showing the shape of the evaluation object 190 used in the evaluation. FIG. 6 shows the evaluation object 190 in a state where it is disassembled into a first member 110 and a second member 120. As shown in FIG. 6, the first member 110 is flat, and the second member 120 is hollow and columnar. In order to prepare the evaluation object 190, the first member 110 was placed on the second member 120 to overlap them, and a laser beam from a Yb fiber laser having a wavelength of about 1070 nanometers was irradiated through the first member 110 to the portion of the second member 120 where the first member 110 was placed, thereby performing laser welding. As a result, the evaluation object 190 in which the joint 130 was formed at the position shown in FIG. 6 was obtained.

[0141] Both the first member 110 and the second member 120 are resin members containing PBT and glass fiber.

[0142] (1) Effect of wavelength First, the influence of the wavelength of light used for evaluation will be described with reference to Figures 7 and 8. Figure 7 is a diagram for comparing the imaging results of an evaluation object 190 imaged with illumination light of different wavelengths.

[0143] A Thorlabs LED was used as the light source of illumination light used to capture each image shown in Figure 7. The numbers written at the top of each image in Figure 7 are the central wavelengths of the LEDs listed on Thorlabs' products, and each LED has components around 50 to 100 nanometers before and after this central wavelength.

[0144] As shown in FIG. 7, when an LED with a central wavelength in the range of 430 nanometers to 660 nanometers is used, only the reflected light from the surface of the first member 110 can be imaged, and the joint 130 cannot be observed at all.

[0145] When an LED with a central wavelength in the range of 730 to 810 nanometers, which is included in the wavelength range from red light to near-infrared light, is used, the reflected light from the back side of first component 110 can also be imaged, and the presence of joint 130 can be confirmed but is unclear. Even when an LED with a central wavelength of 810 nanometers, which is within the near-infrared wavelength range and close to a wavelength of 808 nanometers as disclosed in Patent Document 2, is used, a clear image of joint 130 cannot be obtained.

[0146] When an LED with a central wavelength in the range of 940 nanometers to 1550 nanometers is used, the junction can be clearly imaged. In particular, when an LED with a central wavelength in the range of 1050 nanometers to 1550 nanometers is used, the outline of the junction 130 is clear and the width of the junction 130 can be measured.

[0147] In order to study the wavelength dependency of the image clarity in more detail, the transmittance of the first member 110 was measured using a spectrophotometer. Fig. 8 is a diagram showing the attenuation coefficient of the first member 110. The horizontal axis of Fig. 8 is the wavelength, and the vertical axis of Fig. 8 is the attenuation coefficient. The meaning of the attenuation coefficient is as explained in Fig. 3 above.

[0148] It has been found that the attenuation of light passing through the first member 110 is due to the following factors.

[0149] The first attenuation factor is scattering due to crystal grains and fillers such as glass fibers in the first member 110. In the case of the attenuation coefficient of the first member 110 shown in FIG. 8, this is the reason why the attenuation coefficient decreases monotonically from around 350 nanometers to around 2000 nanometers. As shown in FIG. 7, when an LED with a central wavelength in the range of 430 nanometers to 660 nanometers is used, the existence of the joint 130 cannot be confirmed, and this attenuation is one of the reasons. In addition, when an LED with a central wavelength in the range of 730 nanometers to 810 nanometers is used, the existence of the joint 130 can be confirmed, but the fact that the joint cannot be clearly imaged is also due to this attenuation.

[0150] Whether or not crystal grains occur in a resin depends on the type of resin. Resins such as polyethylene (PE), polypropylene (PP), polyamide (PA), polyacetal polyoxymethylene (POM), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), and polyether ether ketone (PEEK) are so-called crystalline resins, and the resin itself has the property of easily forming crystals. Since the randomly formed crystals in the resin scatter light, crystalline resins have a larger attenuation coefficient than amorphous resins in which crystals do not form.

[0151] A filler is a substance that is mixed into a resin to improve its strength, heat resistance, dimensional stability, and other properties. Fillers are usually melt-kneaded with a resin and dispersed in the resin. A mixture of a resin and a filler is sometimes called a compound.

[0152] The filler is not particularly limited as long as it is a filler for resin, but examples of materials used as fillers include glass fiber, carbon fiber, talc, etc. Some fillers, such as carbon fiber, have absorption in wavelengths such as visible light, while other fillers, such as glass fiber, are transparent to visible light. Even if the filler is transparent to visible light, scattering occurs if it has a different refractive index from the resin. Scattering by the filler occurs whether the resin is a crystalline resin or an amorphous resin.

[0153] The scattering caused by crystal grains and fillers is greater at shorter wavelengths. Therefore, scattering caused by crystal grains and fillers can be reduced by increasing the wavelength used for imaging. This is the reason why, when an LED with a central wavelength in the range of 1050 nanometers to 1550 nanometers is used, it is possible to capture a clear image of the outline of the joint 130 and measure the width of the joint 130, compared to when an LED with a central wavelength in the range of 730 nanometers to 940 nanometers is used.

[0154] The second attenuation factor is due to resonance absorption of the molecules that make up the resin. In the case of the attenuation of the first member 110 shown in Fig. 8, the attenuation peaks near 1650 nm and 2100 nm and the strong attenuation in the wavelength range of 2200 nm or more are due to resonance absorption.

[0155] Attenuation due to resonance absorption originates from the bonds between the elements that make up the resin, and exists whether the resin is crystalline or amorphous. The wavelength position of resonance absorption depends on the bonds between the elements that make up the resin, and differs depending on the type of resin. However, most resins used in laser welding basically have carbon in the main skeleton, and many have bonds such as CH, CC, and CO. Therefore, because there are many common points in the resin structures, there are also many common points in the wavelengths and intensities at which resonance absorption occurs in resins.

[0156] The strength of attenuation due to resonance absorption depends on the mode of resonance absorption. Each mode of resonance absorption has a unique resonant wavelength. Therefore, the strength of attenuation due to resonance absorption is wavelength dependent.

[0157] The inventors have investigated the resonance absorption of various resins that are often used in laser welding and found that the resonance absorption can be explained by dividing it into the following three wavelength ranges.

[0158] The first wavelength range is a range of wavelengths longer than 2200 nanometers. The resonant absorption in the first wavelength range is very strong, and the attenuation is strong throughout the first wavelength range. Light with wavelengths in the first wavelength range is not well suited for evaluation of the bond 130 by irradiating the illumination light through the first member 110.

[0159] The second wavelength range is from 1500 nanometers to 2200 nanometers in wavelength. The resonance absorption in the second wavelength range is weaker than that in the first wavelength range, but is stronger than that in the third wavelength range described below.

[0160] Even in the second wavelength range, the resonance absorption does not exist throughout the entire range of the second wavelength range, so that illumination light including wavelength components different from the wavelength band including the peak of the resonance absorption in the second wavelength range can be used for evaluation of the bonded portion 130.

[0161] The third wavelength range is a range of wavelengths from 1100 nanometers to less than 1500 nanometers. The resonance absorption in the third wavelength range is the weakest among the three wavelength ranges, and some of the resonance absorption is not substantially observed as an attenuation peak. A wavelength range of the illumination light that includes the resonance absorption in the third wavelength range may be selected. In addition, the attenuation coefficient can be further reduced by selecting a wavelength range of the illumination light that avoids the resonance absorption in the third wavelength range.

[0162] Another attenuation factor is absorption by the dye mixed in the resin. When the first member 110 contains a dye, the light in the visible light region is attenuated even more than the attenuation shown in FIG.

[0163] The purpose of mixing the dye into the first member 110 is to make the color tone closer to that of the second member 120, which is mixed with the dye to absorb the laser light. However, due to the characteristics of the laser welding process, the first member 110 needs to have a certain level of transparency to the wavelength of the laser light. Therefore, the dye used in the first member 110 is different from the dye used in the second member 120, and has, for example, absorption mainly in the visible light region, or has almost no absorption at least for wavelengths equal to or longer than the wavelength of the laser light used for welding. Therefore, attenuation by the dye can be avoided by using illumination light that contains components with wavelengths equal to or longer than the wavelength of visible light or the wavelength of the laser light used for welding.

[0164] As described above, there are several factors that cause the attenuation of light passing through the first member 110. The attenuation of light passing through the first member 110 is determined by the sum of the several attenuation factors described above.

[0165] Among the above-mentioned light attenuation, the attenuation in the first wavelength range due to the second attenuation factor and the attenuation due to the pigment have a higher attenuation intensity than the attenuation due to other attenuation factors, so it is preferable to use a wavelength range in which these effects are not apparent for the illumination light used to evaluate the joint 130.

[0166] In addition, when comparing the attenuation in the second wavelength range and the attenuation in the third wavelength range, which range has a smaller attenuation coefficient varies depending on the resin. Since the second wavelength range is on the longer wavelength side, the first attenuation factor (attenuation due to scattering) is smaller in the second wavelength range. Therefore, when a resin with strong scattering is used for the first member 110, the wavelength with the smallest attenuation often exists in the second wavelength range. On the other hand, when a resin with relatively small scattering is used for the first member 110, the wavelength with the smallest attenuation often exists in the third wavelength range.

[0167] As described above, in the evaluation method according to the present embodiment, illumination light 100 containing components of a first wavelength range 201 including wavelengths outside the resonance absorption band of the first resin in the range of 850 nanometers or more and 2200 nanometers or less, and in the range of 1500 nanometers or more and 2200 nanometers or less, is irradiated onto the evaluation object 190.

[0168] As a result, the evaluation object 190 is irradiated with illumination light 100 including a component that is unlikely to be scattered or resonantly absorbed by the first member 110, and the illumination light 100 is likely to pass through the first member 110 and reach the bonded portion 130. Therefore, by imaging using a component in the first wavelength range in the reflected light 101 of the illumination light 100 from a region including the bonded portion 130, an image in which the bonded portion 130 is clearly shown can be obtained. Therefore, the evaluation method according to the present embodiment can improve the imaging quality in evaluation using an image of the bonded portion 130 obtained by laser welding.

[0169] (2) Influence of the angle between the illumination direction and the imaging direction Next, the results of an investigation into the angular relationship between the irradiation direction of the illumination light 100 by the illumination device 150 and the imaging direction in which the reflected light 101 is imaged by the imaging device 160 will be described with reference to FIG. 9A and FIG. 9B. FIG. 9A is a diagram for explaining the positional relationship between the illumination device 150 and the imaging device 160. FIG. 9B is a diagram for comparing the imaging results of the evaluation object 190 imaged by changing the positional relationship between the illumination device 150 and the imaging device 160. In this investigation, as shown in FIG. 9A, the imaging direction D1 of the imaging device 160 was fixed in the vertical direction. Moreover, the evaluation object 190 was inclined by an angle θ1 from the horizontal plane, and was fixed so that the first member 110 was on the upper side of the second member 120. Moreover, the angle formed by the imaging direction D1 and the irradiation direction D2 by the illumination device 150 was set to θ2, and the illumination device 150 was moved to perform imaging at three different values ​​of θ2. The surface of the evaluation object 190, i.e., the surface of the first member 110, is almost flat, and the contact surface of the evaluation object 190 and the surface of the first member 110 are almost parallel to each other. Therefore, the surface of the first member 110 is also inclined at an angle θ1 from the horizontal plane.

[0170] As a result of imaging, it was found that the clarity of the joint 130 in the imaging result changes by changing the angular relationship between the imaging direction D1 and the irradiation direction D2, as shown in FIG. 9B. Specifically, as shown in FIG. 9B (b), when θ2=2θ1, that is, when the angle between the irradiation direction D2 and the surface of the first member 110 and the angle between the imaging direction D1 and the surface of the first member 110 satisfy the mirror reflection state, an imaging result in which the joint 130 is clearly reflected was not obtained. On the other hand, as shown in FIG. 9B (a) and (c), when θ2>2θ1 and θ2<2θ1, respectively, imaging results in which the joint 130 is clearly reflected were obtained. In other words, when the direction of specular reflection by the surface of the first member 110 in the irradiation direction D2 did not match the imaging direction D1, the imaging quality was high.

[0171] The reason why such a result occurred will be explained with reference to Fig. 10. Fig. 10 is a conceptual diagram for explaining the path of illumination light 100 irradiated onto evaluation object 190. Fig. 10 shows a part of the evaluation object 190 including a joint 130.

[0172] 10, part of the illumination light irradiated on the evaluation object 190 is reflected by the surface 110a of the first member 110 of the evaluation object 190, and the other part of the light 100a enters the first member 110. At this time, the direction of the reflected light 101a from the surface 110a basically satisfies the specular reflection condition. Moreover, this reflected light 101a occurs regardless of whether or not the joint 130 is present on the back side of the first member 110.

[0173] On the other hand, the light 100a that has entered the first member 110 undergoes refraction and scattering, with some components traveling toward the bottom surface 110b of the first member 110. Most of the components that have reached the bottom surface 110b of the first member 110 travel toward the second member 120 via the joint 130 in the region of the bottom surface 110b where the joint 130 is formed. On the other hand, some of the components that have reached the bottom surface 110b of the first member 110 are reflected at the interface between the bottom surface 110b and the outside in the region of the bottom surface 110b where the joint 130 is not formed. This reflection occurs not only at the illustrated location, but also at the boundary between the first member 110 and the second member 120 where the joint 130 is not formed by welding. The light 101b that is the component reflected by the bottom surface 110b undergoes scattering and refraction inside the first member 110, with some components exiting from the first member 110 to the surface side of the evaluation target 190. That is, a portion of the light 101b component reflected by the bottom surface 110b becomes reflected light 101c emerging from the surface 110a of the first member 110. Most of the reflected light 101c is emitted in a direction different from that of the specularly reflected light 101a.

[0174] In such a situation, when the imaging device 160 captures the light reflected by the evaluation object 190 from the side of the surface 110a of the first component 110, if the imaging direction D1 and the irradiation direction D2 satisfy the mirror reflection relationship, as in the position shown in (b) of Figure 10, the reflected light 101a from the surface 110a will be captured as the main component, and an image will be obtained that is largely unrelated to the presence or absence of the joint 130.

[0175] On the other hand, when the imaging device 160 captures the light reflected by the evaluation object 190 from the side of the surface 110a of the first member 110, if the imaging direction D1 and the irradiation direction D2 do not satisfy the mirror reflection relationship, as in the positions shown in (a) and (c) of Figure 10, depending on the presence or absence of reflection on the bottom surface 110b of the first member 110, the area other than the joint 130 will be imaged bright due to the reflection of the light 100a, and the area of ​​the joint 130 will be imaged dark.

[0176] In order to obtain an image in which the joint 130 is more clearly visible, the imaging device 160 may capture an image under conditions in which the angle of view does not include the direction of specular reflection by the surface of the first component 110 in the irradiation direction D2.

[0177] In addition, since the surface reflection conditions vary depending on the characteristics of the first component 110, when evaluating the first component 110 and / or conditions under which the illumination light 100 is not easily reflected from the surface, an image in which the joint 130 is clearly visible can be obtained even if the imaging direction D1 and the irradiation direction D2 satisfy the mirror reflection relationship.

[0178] (Embodiment 2) Next, a description will be given of embodiment 2. In embodiment 2, a description will be given of a weld deposit manufacturing apparatus using the evaluation apparatus according to embodiment 1. In the following description of embodiment 2, differences from embodiment 1 will be mainly described, and descriptions of commonalities will be omitted or simplified.

[0179] [Overall configuration of the welding production equipment] First, the overall configuration of the welded product manufacturing apparatus according to this embodiment will be described with reference to Fig. 11, which is a diagram showing the configuration of the welded product manufacturing apparatus according to this embodiment.

[0180] As shown in FIG. 11, the welded product manufacturing apparatus 500 includes a laser irradiation device 510 and an evaluation device 520. The welded product manufacturing apparatus 500 may also include a control device 530 and a light-shielding housing 180 for blocking ambient light. The laser irradiation device 510 and the evaluation device 520 operate, for example, based on the control of the control device 530 or the user's operation. The welded product manufacturing apparatus 500 may further include a stage and a display device described in the evaluation device 170 according to the first embodiment. The welded product manufacturing apparatus 500 forms an evaluation target 190 by forming a joint 130 using the laser irradiation device 510, and evaluates the formed joint 130 using the evaluation device 520. In other words, the welded product manufacturing apparatus 500 can also be said to be an evaluation device having a function of forming the joint 130.

[0181] The basic configuration of the evaluation device 520 is similar to that of the evaluation device 170 described in the embodiment 1. The evaluation device 520 includes, for example, the illumination device 150 and the imaging device 160 described above.

[0182] The laser irradiation device 510 irradiates the second member 120 with laser light 550 through the first member 110. In this way, the laser irradiation device 510 forms a joint 130 in which the first member 110 and the second member 120 are welded together.

[0183] The laser irradiation device 510 includes, for example, a laser light source that emits the laser light 550 and an optical system that guides the laser light 550 as necessary. In the present embodiment, the wavelength of the laser light 550 is not limited in principle. From the viewpoints of ease of resin processing, ease of availability, and stability of operation, for example, a diode laser with a wavelength of 980 nanometers or a fiber laser with a wavelength of 1070 nanometers may be used as the laser light source. In addition, the wavelength of the laser light 550 is, for example, within a first wavelength range or a wavelength in the vicinity of the first wavelength range. In other words, the imaging device 160 of the evaluation device 520 may have sensitivity to both the wavelength range of the illumination light 100 and the wavelength of the laser light 550.

[0184] When the imaging device 160 has sensitivity to the wavelength of the laser light 550, the imaging device 160 may capture an image of the area irradiated with the laser light 550 during the period in which the laser light 550 is irradiated, and obtain an imaging result that can specify the irradiation range of the laser light 550. If, for example, irradiation of an unexpected position occurs due to the specification of the irradiation range of the laser light 550, the user or the control device 530 can correct the irradiation position of the laser light 550 based on the imaging result that can specify the irradiation range of the laser light 550.

[0185] Furthermore, the imaging device 160 may capture an image using the illumination light 100 while the joint 130 is being formed by the laser irradiation device 510, and obtain an imaging result that identifies the area where the joint 130 has been formed.

[0186] In this embodiment, the imaging device 160 may include a configuration having a wavelength discrimination function such as an on-chip wavelength filter. In addition, the central wavelength of the illumination light 100 and the central wavelength of the laser light 550 may be different. The imaging device 160 may output an imaging result in which the laser light 550 and the illumination light 100 are distinguished from each other by the wavelength discrimination function. When the imaging device 160 has this wavelength discrimination function, the imaging device 160 can simultaneously or continuously capture images of the irradiation area of ​​the laser light 550 and the area where the joint 130 is formed during irradiation of the laser light 550, and output an image that specifies the irradiation range of the laser light 550 and the area where the joint 130 is formed.

[0187] The control device 530 controls the operation of the laser irradiation device 510 in addition to the functions of the control device 140 according to the first embodiment, for example.

[0188] [Operation of the welding production equipment] Next, an example of the operation of the welded product manufacturing apparatus 500 according to this embodiment will be described. Specifically, a method for manufacturing a welded product using the welded product manufacturing apparatus 500 will be described. Fig. 12 is a flow chart showing an example of the method for manufacturing a welded product using the welded product manufacturing apparatus according to this embodiment.

[0189] 12, first, as a preparation step, the first member 110 and the second member 120 to be welded are placed at a position where they can be irradiated with laser light 550 (step S21). For example, the second member 120 is placed on a stage, and the first member 110 is further placed on the second member 120. At this time, a lighting device 150 and an imaging device 160 may be used to confirm whether the first member 110 and the second member 120 are in predetermined positions, or to measure the positions of the first member 110 and the second member 120 more accurately.

[0190] Next, as a welding step, the laser irradiation device 510 irradiates a portion of the second member 120 where the joint 130 is to be formed with laser light 550 through the first member 110, thereby forming the joint 130 by welding the first member 110 and the second member 120 together (step S22). The irradiation portion of the laser light 550 may be changed by a method of changing the optical path of the laser light 550 using an optical system such as a galvanometer mirror, or by a method of moving the first member 110 and the second member 120 or the laser irradiation device 510 using an electric stage or the like.

[0191] As described above, the imaging device 160 may be used to check the irradiation range of the laser light 550.

[0192] After the laser light irradiation to the predetermined range is completed, the laser irradiation device 510 stops irradiating the laser light 550 .

[0193] Next, as an evaluation step, the joint 130 is evaluated using the evaluation device 520 (step S23). In step S23, for example, the operations from step S12 to step S14 of the evaluation method according to the first embodiment are performed. Also, in step S23, for example, the evaluation object 190 welded by the laser irradiation device 510 is evaluated while being placed on the stage used for the welding process. That is, the evaluation object 190 to be evaluated is prepared by steps S21 and S22.

[0194] Next, as a repair step, the laser irradiation device 510 repairs the joint 130 based on the result of evaluating the joint 130 in step S23 (step S24). For example, in step S23, it is determined whether or not there is a defective welded portion, and if it is determined that there is a defective portion, the laser irradiation device 510 performs additional laser welding for correcting the defective portion. In this way, it may be determined whether or not to repair the joint 130 based on the result of evaluating the joint 130. This makes it possible to reduce the occurrence of defective products. After step S24, step S23 may be performed again.

[0195] Through the steps described above, a welded product in which the first member 110 and the second member 120 are welded together is produced.

[0196] The method for manufacturing a welded product according to this embodiment does not need to include a repair step. For example, if it is determined in step S23 that there is no defective weld, the welding process is terminated. Also, for example, in the method for manufacturing a welded product according to this embodiment, evaluation may be performed in step S23, and the welding process may be terminated regardless of the evaluation result.

[0197] (Other embodiments) The evaluation device, evaluation method, weld deposit manufacturing device, and weld deposit manufacturing method according to the present disclosure have been described above based on the embodiments, but the present disclosure is not limited to these embodiments.

[0198] For example, in the above embodiment, the evaluation device and the welded product manufacturing apparatus are integrated in such a manner that all the devices are provided within a housing, but this is not limiting. At least one of the devices provided in the evaluation device and the welded product manufacturing apparatus may be provided outside the housing. Also, the evaluation device and the welded product manufacturing apparatus may not have a housing.

[0199] For example, the evaluation device and the weld deposit manufacturing device do not need to include all of the components described in the above embodiments, and may be composed of only the components required to perform the intended operation.

[0200] Furthermore, for example, the control device does not have to be a standalone device. For example, a lighting device, an imaging device, or a laser irradiation device may have the function of a control device.

[0201] In addition, for example, the evaluation device and the welded material manufacturing device may be equipped with a communication unit, and the control device may be an external device such as a user's smartphone, a dedicated device brought by the user, or a cloud server, and evaluation may be performed by the evaluation device and the welded material manufacturing device communicating with the external device using the communication unit.

[0202] In the above embodiment, the processes executed by a specific processing unit may be executed by another processing unit. The order of multiple processes may be changed, or multiple processes may be executed in parallel.

[0203] In the above embodiment, the functions of the control device may be realized by executing a software program suitable for the control device. The control device may be realized by a program execution unit such as a CPU or a processor reading and executing a software program recorded on a recording medium such as a hard disk or a semiconductor memory.

[0204] The control device may be realized by hardware. The control device may be a circuit (or an integrated circuit). These circuits may form a single circuit as a whole, or each may be a separate circuit. Each of these circuits may be a general-purpose circuit or a dedicated circuit.

[0205] In addition, the general or specific aspects of the present disclosure may be realized in a system, an apparatus, a method, an integrated circuit, a computer program, or a computer-readable recording medium such as a CD-ROM, or may be realized in any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium.

[0206] In addition, as long as they do not deviate from the spirit of the present disclosure, various modifications that would come to mind by a person skilled in the art to the embodiments, as well as other forms constructed by combining some of the components of the embodiments, are also included in the scope of the present disclosure. [Industrial Applicability]

[0207] The present disclosure can be used for inspecting the joints of resin welded products, or for checking the joints during welding processing. [Explanation of symbols]

[0208] 100 Illumination Light 100a, 101b light 101, 101a, 101c reflected light 110 First member 110a surface 110b Bottom 120 Second Component 130 Joint 140, 530 Control device 150 Lighting Equipment 151 Light source 152 Illumination optical system 153, 163 Optical filters 160 Imaging Device 161 Image sensor 162 Imaging Optical System 170, 520 Evaluation device 180 Light-shielding housing 190 Evaluation Object 201 First Wavelength Range 202 Second Wavelength Range 203 Third Wavelength Range 210 Resonance absorption band 211 Arrow Line 220 Wavelength Band 500 Welding equipment 510 Laser irradiation device 550 Laser Light D1 Imaging direction D2 Irradiation direction

Claims

1. 1. A method for evaluating a joint between a first member and a second member welded by laser light, comprising the steps of: irradiating an evaluation object including the first member and the second member with first light such that the first light including a component in a first wavelength range is irradiated to the joint through the first member; and capturing an image of a component of the first wavelength range in the reflected light of the first light by the evaluation object, the first member includes a first resin; the first wavelength range is within a range of 850 nanometers to 2200 nanometers, and includes wavelengths other than the resonance absorption band of the first resin in the range of 1500 nanometers to 2200 nanometers. Evaluation method.

2. The first light is incoherent light. The evaluation method according to claim 1 .

3. The first light has a wavelength of less than 850 nanometers at 50% or less. The evaluation method according to claim 1 or 2.

4. The direction in which the first light is specularly reflected by the surface of the first member does not coincide with the imaging direction in which the reflected light is imaged. The evaluation method according to any one of claims 1 to 3.

5. The first light has a component in the first wavelength range of more than 50%. The evaluation method according to any one of claims 1 to 4.

6. The first wavelength range is within the range of 1050 nanometers to 2200 nanometers. The evaluation method according to any one of claims 1 to 5.

7. Among the components in the first wavelength range contained in the first light, components with wavelengths other than the resonance absorption band are more numerous than components with wavelengths in the resonance absorption band. The evaluation method according to any one of claims 1 to 6.

8. A method for producing a welded product in which the first member and the second member are welded by the laser light, comprising the steps of: forming the joint by welding the first member and the second member by irradiating the second member with the laser light through the first member; and evaluating the joint using the evaluation method according to any one of claims 1 to 7. Method for manufacturing weld deposits.

9. and repairing the joint based on the results of evaluating the joint. A method for producing the weld deposit according to claim 7.

10. An evaluation device for evaluating a joint between a first member and a second member welded by laser light, comprising: an illumination device that irradiates an evaluation object including the first member and the second member with first light such that the first light includes a component in a first wavelength range and is irradiated to the joint through the first member; an imaging device that captures an image using a component in the first wavelength range in the reflected light of the first light by the evaluation object, the first member includes a first resin; the first wavelength range is within a range of 850 nanometers to 2200 nanometers, and includes wavelengths other than the resonance absorption band of the first resin in the range of 1500 nanometers to 2200 nanometers. Evaluation equipment.

11. The illumination device and the imaging device are arranged so that a direction in which the first light is specularly reflected by a surface of the first member in an irradiation direction of the first light from the illumination device does not coincide with an imaging direction in which the reflected light is captured by the imaging device. The evaluation device according to claim 10.

12. a laser irradiation device that irradiates the laser light through the first member to the second member to form the joint by welding the first member and the second member; The evaluation device according to claim 10 or 11, Welding production equipment.

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