Sputter measurement system

Abstract

The apparatus comprises a camera that captures an image of an observation area including a molten portion, a spot light source that irradiates a spot light toward the side of the observation area as viewed from the camera, and a control device that measures the size of the sputter based on the image captured by the camera.

Description

Technology Field

[0001] The present disclosure relates to a technique for measuring sputter generated during welding. Background Technology

[0002] When welding metals, droplet-shaped molten metal particles (sputter) may scatter from the surface of the molten zone during welding. Since sputter can degrade the quality of the product after welding, it is desirable to suppress the occurrence of sputter. To do so, it is first necessary to measure the occurrence of sputter.

[0003] As an example of a device for measuring the occurrence of sputter, for instance, Japanese Patent Publication No. 2019-188421 discloses a device capable of measuring the number of sputters by image processing data obtained by photographing a welded part with a camera during welding.

[0004] Among the sputters ejected from the molten zone, there are not only sputters with high self-luminescence but also those with low self-luminescence. Therefore, simply photographing the sputters with a camera may not capture images of the sputters with low self-luminescence ejected from the molten zone, and thus may make it impossible to measure the sputters and their sizes.

[0005] The present disclosure is made to solve the aforementioned problem, and its purpose is to measure the size of a sputter with high precision even when the amount of self-luminescence of the sputter is low.

[0006] (Clause 1) A sputter measurement system according to the present disclosure is a sputter measurement system for measuring the size of sputters ejected from a molten part that is melted during welding, and comprises a camera for capturing an image of an observation area including a molten part, a spot light source for irradiating a spot light from a side of the observation area toward the observation area as viewed from the camera, and a control device for measuring the size of the sputter based on the image captured by the camera.

[0007] (Clause 2) The sputter measurement system described in Clause 1 further comprises a telecentric lens positioned between the melting section and the camera.

[0008] (Clause 3) In the sputter measurement system described in Clause 2, the location of the melting part is included within the depth of field range of the telecentric lens, and further comprises a member having a slit disposed between the melting part and the spot light source to match the irradiation range of the spot light to the depth of field range of the telecentric lens.

[0009] The above and other objects, features, aspects, and advantages of the present invention will become clear from the following detailed description of the present invention as understood in conjunction with the accompanying drawings. Brief explanation of the drawing

[0010] Figure 1 is a schematic diagram showing an example of the overall configuration of a sputter measurement system. Figure 2 is a diagram (Figure 1) schematically illustrating the measurement principle of sputtering. Figure 3 is a diagram showing an example of an image of an observation area captured by a camera. Figure 4 is a diagram (Figure 2) schematically illustrating the measurement principle of sputtering. Specific details for implementing the invention

[0011] [System Configuration]

[0012] FIG. 1 is a schematic diagram showing an example of the overall configuration of a sputter measurement system (1) according to the present embodiment. Metal base materials (2, 3) are welded by a processing laser beam (5) emitted from a laser generating device not shown. During welding, the location where the laser beam (5) is irradiated melts and becomes a molten part (6). By moving the laser generating device in the welding direction (the Y direction in the drawing), a weld bead extending in the Y direction in the drawing is formed. In addition, in the drawing, the Y direction represents the welding direction described above, the Z direction represents the normal direction of the base materials (2, 3), and the X direction represents a direction orthogonal to the Y direction and the Z direction.

[0013] When welding base materials (2, 3), sputter (7) may be ejected from the molten area (6). Sputter (7) may degrade the quality of the product after welding. For example, in the case of welding to wire the cell terminals and bus bar of a battery, if sputter (7) is ejected, it may penetrate the resin coating material covering the surrounding wiring, causing the wiring to be short-circuited or disconnected, or the sputter (7) may adhere between the welding pins of the surrounding substrate, causing the circuit of the substrate to be short-circuited. Therefore, it is desirable to suppress the generation of sputter (7) itself, or to ensure that it does not cause problems even if sputter (7) is generated. To do this, it is first required to measure the generation of sputter.

[0014] In light of this, the sputter measurement system (1) according to the present embodiment is configured to measure the size (dimensions) of the sputter (7) scattered from the melting part (6). Specifically, the sputter measurement system (1) is equipped with a spot light source (10R, 10L), a camera (30), a telecentric lens (40), and a control device (100).

[0015] The camera (30) takes a high-speed image of an observation area including a melting part (6) that is melted by a laser light (5). The camera (30) outputs the image data obtained by the shooting to a control device (100). In addition, a blackout curtain (4) that does not reflect light is placed on the back side of the observation area as viewed from the camera (30).

[0016] The telecentric lens (40) is placed in the light path between the melting section (6) and the camera (30). Unlike a normal lens, the telecentric lens (40) is a special lens capable of producing light in which the main optical axis is parallel to the optical axis of the lens. Due to its optical characteristics, the telecentric lens (40) has an area (hereinafter also referred to as "depth of field area R1") in which the size of the subject image does not change even when the distance between the camera (30) and the subject changes. Therefore, by photographing the subject sputter (7) with the camera (30) through the telecentric lens (40), as long as the sputter (7) is included in the depth of field region R1 of the telecentric lens (40), the size of the image of the sputter (7) does not change regardless of the position of the sputter (7) (even if the position of the sputter (7) deviates from the focal position due to scattering), and no image distortion due to parallax occurs.

[0017] Among the sputters ejected from the melting section (6), there are sputters with a large amount of self-luminous light, as well as sputters with a small amount of self-luminous light. Therefore, simply photographing the sputters (7) with a camera (30) does not allow for the capture of images of the sputters with a small amount of self-luminous light among the sputters (7) ejected from the melting section (6), and thus there are cases where the sputters and their sizes cannot be measured.

[0018] In light of this, the sputter measurement system (1) according to the present embodiment is equipped with a spot light source (10R, 10L). The spot light source (10R, 10L) emits a spot light that diffuses in a conical shape as an illumination light for sputter observation. The spot light source (10R, 10L) is positioned so that it faces each other with a molten part (6) interposed between them.

[0019] The spot light source (10R) emits a spot light toward the right side of the observation area including the melting part (6) as viewed from the camera (30). Specifically, the spot light source (10R) includes a light source (11R) that generates high-intensity light according to a command from the control device (100), and a light source lens (12R) that emits the light generated by the light source (11R) as a spot light toward the melting part (6). The optical axis of the light source lens (12R) is orthogonal to the optical axis of the camera (30).

[0020] The spot light source (10L) emits a spot light toward the left side of the observation area containing the melting part (6) as viewed from the camera (30). Specifically, the spot light source (10L) includes a light source (11L) that generates high-intensity light according to a command from the control device (100), and a light source lens (12L) that emits the light generated by the light source (11L) as a spot light toward the melting part (6). The optical axis of the light source lens (12L) is orthogonal to the optical axis of the camera (30).

[0021] The control device (100) includes a CPU (Central Processing Unit) and memory such as ROM (Read Only Memory) and RAM (Random Access Memory). When welding base materials (2, 3), the control device (100) operates a spot light source (10R, 10L) to illuminate an observation area including a molten part (6) with spot light from the side, and measures the size of the sputter (7) flying from the molten part (6) based on image data captured by a camera (30) in that state.

[0022] FIG. 2 is a schematic diagram illustrating the principle of measuring sputter (7) by a sputter measurement system (1). The measurement of sputter (7) is performed in-process during the welding of base materials (2, 3).

[0023] The observation area captured by the camera (30) includes a depth of field area R1 of the telecentric lens (40), a remote area R2 that is further from the camera (30) than the depth of field area R1, and a close area R3 that is closer to the camera (30) than the depth of field area R1. Additionally, the depth of field area R1 is a range within a few millimeters from the focal position.

[0024] During the measurement of the sputter (7), the relative position in the Y direction between the melting part (6) and the telecentric lens (40) is adjusted so that the melting part (6) is included in the depth of field region R1 of the telecentric lens (40). Additionally, the relative position in the Y direction between the melting part (6) and the light source lens (12R, 12L) is adjusted so that the spot light (21R, 21L) illuminates the observation area including the melting part (6). Furthermore, in this embodiment, the relative position in the X direction between the melting part (6) and the light source lens (12R, 12L), or the irradiation angle (magnification) of the spot light (21R, 21L), is adjusted so that the irradiation range of the spot light (21R, 21L) almost coincides with the depth of field region R1.

[0025] When there is no sputter (7) in the observation area, the object illuminated by the spot light (21R, 21L) is not present in the observation area, and only the dark screen (4) is captured by the camera (30), so the entire image of the observation area becomes a dark spot.

[0026] Meanwhile, when a sputter (7) is present in the depth of field region R1 of the telecentric lens (40), spot light (21R, 21L) is irradiated onto the left and right sides of the sputter (7), respectively. As a result, diffuse light (scattered light) is generated on the left and right sides of the sputter (7), and the parallel light passing through the telecentric lens (40) among the diffuse light is captured by the camera (30). Therefore, the left and right side shapes of the sputter (7) are captured as bright spots. That is, in this embodiment, the left and right side shapes of the sputter (7) are captured by the camera (30) by shining spot light (21R, 21L) on the side of the sputter (7) to be measured. The control device (100) measures the size of the sputter (7) from the side shape of the sputter (7) captured by the camera (30). As a result, even when the amount of self-emission of the sputter (7) is low, the sputter (7) and its size can be measured with high precision.

[0027] FIG. 3 is a drawing showing an example of an image of an observation area captured by a camera (30). The bright spots (7R, 7L) included in the image of the observation area are images of the right and left edge shapes of the sputter (7) existing within the depth of field area R1. The control device (100) estimates the shape of the entire sputter (7) from the shape of the bright spots (7R, 7L) and measures the size (dimensions) of the sputter (7) from the estimated entire shape.

[0028] When the sputter (7) is located within the depth of field region R1 of the telecentric lens (40), the measured size of the sputter becomes nearly constant regardless of the perspective of the sputter. Therefore, as long as the sputter (7) is located within the depth of field region R1, the size (dimensions) of the sputter (7) can be measured with high precision even if the sputter (7) moves due to scattering.

[0029] Returning to Fig. 2, when the sputter is located in the remote area R2 or the nearby area R3, the size of the sputter image changes depending on the perspective of the sputter (distance to the camera (30)), making it difficult to accurately measure the size of the sputter.

[0030] In light of this, in this embodiment, the irradiation range of the spot light (21R, 21L) is adjusted to almost coincide with the depth of field area R1, as described above. Therefore, the sputters in the remote area R2 and the close area R3 are not illuminated by the spot light (21R, 21L) and thus are not illuminated in the image of the observation area. As a result, the sputters (7) present in the remote area R2 and the close area R3, where the size of the image changes depending on the distance, are excluded from the target of dimensional measurement. Therefore, the decrease in the measurement precision of the sputters (7) is suppressed.

[0031] As described above, in the sputter measurement system (1) according to the present embodiment, spot light (21R, 21L) is irradiated onto the side of the sputter (7) to generate diffused light (scattered light) on the side of the sputter (7), and the diffused light is captured by a camera (30) to measure the side shape of the sputter (7), and the size of the sputter is measured from the measured side shape of the sputter. As a result, even when the amount of self-emission of the sputter (7) is small, the size of the sputter (7) can be measured.

[0032] In addition, in the sputter measurement system (1) according to the present embodiment, a telecentric lens (40) is positioned between the melting section (6) and the camera (30). Therefore, the size of the sputter can be measured with high precision regardless of the distance of the sputter.

[0033] [Variation Example 1]

[0034] In the above-described embodiment, the irradiation range of the spot light (21R, 21L) is aligned with the depth of field region R1 by adjusting the relative position in the X direction between the melting part (6) and the light source lens (12R, 12L) or the irradiation angle of the spot light (21R, 21L). However, the method of aligning the irradiation range of the spot light (21R, 21L) with the depth of field region R1 is not limited to this method.

[0035] FIG. 4 is a schematic diagram illustrating the measurement principle of a sputter (7) by a sputter measurement system (1A) according to the present variation 1. The sputter measurement system (1A) is a sputter measurement system (1) with respect to the sputter measurement system (1) shown in FIG. 1 above, with a slit plate (50R, 50L) added.

[0036] The slit plate (50R) is positioned between the melting section (6) and the light source lens (12R) and has a slit (51R) for aligning the irradiation range of the spot light (21R) with the depth of field area R1 of the telecentric lens (40).

[0037] The slit plate (50L) is positioned between the melting section (6) and the light source lens (12L) and has a slit (51L) for aligning the irradiation range of the spot light (21L) with the depth of field area R1 of the telecentric lens (40).

[0038] In this way, by placing a slit plate (50R, 50L) between the melting section (6) and the light source lens (12R, 12L), the irradiation range of the spot light (21R, 21L) may be aligned with the depth of field area R1.

[0039] [Variation Example 2]

[0040] In the above-described embodiment, the left and right sides of the sputter were illuminated with two spot light sources (10R, 10L), but one side of the sputter may be illuminated with a single spot light source. Even in this way, the shape of one side of the sputter can be measured, the shape of the entire sputter (7) can be estimated from the measured side shape, and the size of the sputter (7) can be measured from the estimated entire shape.

[0041] Although embodiments of the present invention have been described, the embodiments disclosed herein should be considered illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, and all modifications within the meaning and scope equivalent to the claims are intended to be included.

Claims

Claim 1 A sputter measurement system for measuring the size of sputters scattered from a molten part during welding, comprising a camera for capturing an image of an observation area including the molten part, a spot light source for irradiating a spot light from a side of the observation area toward the observation area as viewed from the camera, and a control device for measuring the size of the sputters based on the image captured by the camera, and further comprising a telecentric lens disposed between the molten part and the camera. Claim 2 A sputter measurement system according to claim 1, wherein the location of the melting portion is included within the depth of field range of the telecentric lens, and further comprises a member disposed between the melting portion and the spot light source and having a slit for aligning the irradiation range of the spot light with the depth of field range of the telecentric lens. Claim 3 delete

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