Visual inspection device for heat exchanger, method of manufacturing heat exchanger, and visual inspection method for heat exchanger

Abstract

To solve the problem that a conventional visual inspection device has a large number of components since an image obtained by photographing reflected light by an imaging camera is used and lighting and a camera are therefore required on each of the reverse surface side and top surface side of an inspected surface of an object to be inspected.SOLUTION: A visual inspection device comprises: a light source which emits light to a heat exchanger having a plurality of fins arranged at predetermined intervals; a light reception part which receives and converts light, passing between adjacent fins, of the light into an electric signal, and then outputs it; and a processing unit which determines whether the fins are properly arranged from peaks that the electric signal has.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a visual inspection device for a heat exchanger, a manufacturing method for a heat exchanger, and a visual inspection method for a heat exchanger. [Background technology]

[0002] Traditionally, manufacturing industries require inspections to detect defects in products. Although the contents and items of inspections vary widely depending on the manufacturing field and product, the inspection method of judging the quality of products by their appearance is an important method in common. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-321300 A Summary of the Invention [Problem to be solved by the invention]

[0004] The appearance inspection device disclosed in Patent Document 1 uses images captured by a camera that captures reflected light, and therefore requires lighting and a camera on both the front and back sides of the object to be inspected in order to capture the front and back surfaces of the object to be inspected. This poses the problem of an increased number of parts.

[0005] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide a visual inspection device with a reduced number of parts. [Means for solving the problem]

[0006] The visual inspection device disclosed herein includes a light source that irradiates light onto a heat exchanger having multiple fins arranged at a predetermined interval, a light receiving unit that receives light that passes between adjacent fins and converts it into an electrical signal to output, and a processing device that determines whether the fin arrangement is good or bad from the peak indicated by the electrical signal. Effect of the Invention

[0007] According to the appearance inspection device of the present disclosure, the light receiving unit converts the light that passes between adjacent fins out of the light irradiated onto the heat exchanger by the light source into an electrical signal, and the processing device judges whether the fin arrangement is good or not from the peak indicated by the electrical signal. Since the light source can be placed on either side of the heat exchanger and the light receiving unit on the other side, the appearance inspection device of the present disclosure can reduce the number of parts. [Brief description of the drawings]

[0008] [Figure 1] 1 is a configuration diagram of a visual inspection device according to a first embodiment. [Diagram 2] 2 is a schematic diagram showing a state in which the visual inspection device in the first embodiment is inspecting a heat exchanger. FIG. [Diagram 3] 1 is a functional block diagram of a visual inspection device according to a first embodiment. FIG. [Figure 4] 2 is a schematic diagram of a light receiving section in the first embodiment. FIG. [Diagram 5] 5A to 5C are schematic diagrams showing a case where the fins of the heat exchanger in the first embodiment are not defective and a case where they are defective. [Figure 6] 11 shows data indicated by electrical signals when there is no defect in the arrangement of fins and when there is a defect in the arrangement of fins in the first embodiment. [Figure 7] 4 is a flowchart showing an inspection method in the first embodiment. [Figure 8] 4 is a flowchart showing the operation of an inspection process of the visual inspection apparatus in the embodiment 1. [Figure 9] 4 is a schematic diagram showing a first example of a determination method performed by a determination unit in the first embodiment. FIG. [Figure 10] FIG. 11 is a schematic diagram showing a second example of the determination method performed by the determination unit in the first embodiment. [Figure 11] FIG. 2 is a configuration diagram showing a hardware configuration of a processing device according to the first embodiment. [Figure 12]4 is a flowchart showing a method for manufacturing the heat exchanger in the first embodiment. [Figure 13] 10 is a schematic diagram showing a state in which a heat exchanger is placed on a holder in the first modification of the first embodiment. FIG. [Figure 14] FIG. 13 is a schematic diagram showing a case where an inspection is performed in a darkroom in the second modification of the first embodiment. [Figure 15] FIG. 11 is a schematic diagram showing a difference in peaks exhibited by an electric signal when a darkroom is used and when it is not used in the second modification of the first embodiment. [Figure 16] FIG. 11 is a schematic diagram showing a state in which a visual inspection device in the second embodiment is inspecting a heat exchanger. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments will be described with reference to the drawings. In each drawing, the same reference numerals are used to denote common or corresponding elements, and the description is simplified or omitted. The configurations shown in the embodiments below are examples of the technical ideas of the present disclosure, and may be combined with other known technologies, or multiple technical ideas described in the present disclosure may be combined. In addition, it is also possible to omit or modify a part of the configuration without departing from the gist of the present disclosure.

[0010] Embodiment 1 1 is a configuration diagram of an appearance inspection device 1 in embodiment 1. The appearance inspection device 1 is a device that inspects a heat exchanger 2 having a plurality of plate-shaped fins arranged at a predetermined interval to determine whether there are any defective fin arrangements. The appearance inspection device 1 includes a light source 11, a holder 12, a light receiving unit 13, a processing device 14, and a display device 15.

[0011] FIG. 2 is a schematic diagram showing the appearance inspection device 1 inspecting the heat exchanger 2. Hereinafter, the description will be given using three-dimensional coordinates in which the longitudinal direction of the surface of the fin 20 is the X-axis direction, the direction perpendicular to the surface of the fin 20 is the Y-axis direction, and the direction perpendicular to the X-axis direction and the Y-axis direction is the Z-axis direction. In addition, the description will be given assuming that the +Z direction is upward and the -Z direction is downward. The length of the heat exchanger 2 in the X-axis direction is Wx [m], and the length in the Y-axis direction is Dy [m]. Also, a certain point on the heat exchanger 2 is set as the origin of the three-dimensional coordinate system. In this embodiment, the description will be given in the case where the origin is one of the four corners of the upper surface of the heat exchanger 2. Also, in this embodiment, the range occupied by the fin 20 when the heat exchanger 2 is viewed from the Z-axis direction is set as the inspection range of the heat exchanger 2.

[0012] The light source 11 irradiates light perpendicularly to the XY plane from above the heat exchanger 2, that is, from the +Z direction in FIG. 2. The light source 11 is, for example, a line light source, and irradiates the heat exchanger 2 with parallel light. The line light source is realized, for example, when one linear light emitting element is used. Note that the line light source may be realized by arranging a plurality of point-like light emitting elements in one or more rows. The parallel light is realized, for example, by using a polarizing film. The light source 11 is, for example, a laser light source or an LED. The light irradiated by the light source 11 may be light that can be sensed by the photodiode 131 described later.

[0013] The range Ly [m] of the light irradiated by the light source 11 in the Y-axis direction is equal to or greater than the length Dy [m] of the heat exchanger 2 in the Y-axis direction. The light source 11 is disposed so that the longitudinal direction of the line light source is parallel to the Y-axis direction, and is scanned in the +X direction. This allows the light source 11 to irradiate light over the entire inspection range of the heat exchanger 2. The light source 11 is scanned by a light source scanning drive unit (not shown). The light source scanning drive unit is composed of a motor, a ball screw, and a guide rail. The ball screw and the guide rail are installed so that their longitudinal directions are parallel to the X-axis direction. The distance Lx [m] scanned by the light source 11 is equal to or greater than the length Wx [m] of the heat exchanger 2 in the X-axis direction. The light source scanning drive unit is controlled by a light source control unit (not shown). The light source control unit controls the position of the light source 11 via the light source scanning drive unit. The light source control unit may also control the intensity of the light irradiated by the light source 11 or the time for irradiating the light.

[0014] The light irradiated to the heat exchanger 2 passes between adjacent fins 20. The light that passes between adjacent fins 20 is called transmitted light. The light used for the light source 11 is not particularly limited. When visual confirmation by a person is also performed, the light source 11 may be a green laser with excellent visibility.

[0015] The holding unit 12 clamps the side of the heat exchanger 2 to fix the heat exchanger 2 at a position between the light source 11 and the light receiving unit 13. The side of the heat exchanger 2 clamped by the holding unit 12 may be, for example, an XZ plane or a YZ plane. In addition, it is preferable that the holding unit 12 does not cover the upper and lower surfaces of the heat exchanger 2 when clamping the heat exchanger 2. The holding unit 12 has, for example, a reference block 121 and a clamp 122. The heat exchanger 2 is positioned by aligning the side with the reference block 121 fixed at a predetermined position. The clamp 122 clamps the heat exchanger 2 together with the reference block 121. The clamp 122 can change the strength with which the heat exchanger 2 is fixed by changing the tightening strength.

[0016] The light receiving unit 13 is disposed at a position opposite to the light source 11 with respect to the heat exchanger 2. The light receiving unit 13 receives light that passes between adjacent fins among the light irradiated by the light source 11 to the heat exchanger 2, and converts it into an electrical signal. The length lx [m] of the range in which the light receiving unit 13 receives light in the X-axis direction is longer than the scanning distance Wx [m] of the heat exchanger 2 in the X-axis direction. In addition, the length ly [m] of the range in which the light receiving unit 13 receives light in the Y-axis direction is equal to or longer than the length Dy [m] of the heat exchanger 2 in the Y-axis direction. The distance between the light source 11 and the heat exchanger 2 and the distance between the heat exchanger 2 and the light receiving unit 13 in the Z-axis direction are appropriately set according to the specifications of the light source 11 and the light receiving unit 13.

[0017] FIG. 3 is a functional block diagram of the appearance inspection device 1. The light receiving unit 13 includes a photodiode 131 and a photodiode amplifier 132. The photodiode 131 receives the passing light and converts it into an electric current. The magnitude of the electric current is proportional to the intensity of the light received by the photodiode 131. The photodiode 131 can detect the passing light. For example, when the light source 11 irradiates a green laser, the photodiode 131 is a Si photodiode with a detection wavelength range of 400 nm to 1100 nm. The photodiode 131 outputs the converted electric current to the photodiode amplifier. The photodiode amplifier 132 converts the electric current output by the photodiode 131 into a voltage. The photodiode amplifier 132 outputs the converted voltage value to the processing device 14 as an electric signal.

[0018] 4 is a schematic diagram of the light receiving unit 13. The photodiodes 131 are arranged in a matrix within a range in which the light receiving unit 13 receives light, that is, within a rectangular range having a length lx [m] in the X-axis direction and a length ly [m] in the Y-axis direction. The range in which the light receiving unit 13 receives light corresponds to an inspection range of the heat exchanger 2, and the size of the range in which the light receiving unit 13 receives light is equal to or larger than the size of the inspection range of the heat exchanger 2. The photodiodes 131 are arranged such that a photodiode pitch Py [m], which is the distance between the centers of adjacent photodiodes 131 in the Y-axis direction, is smaller than half the fin pitch P [m], which is the distance between adjacent fins 20.

[0019] The photodiode pitch Px [m], which is the distance between the centers of adjacent photodiodes 131 in the X-axis direction, does not have to be smaller than the fin pitch P [m], which is the distance between adjacent fins 20. However, a smaller photodiode pitch Px allows more electrical signals to be acquired than a larger photodiode pitch Px, thereby improving the inspection accuracy.

[0020] 3, the processing device 14 includes a storage unit 141, an input unit 142, a determination unit 143, and an output unit 144. The storage unit 141 stores data used when determining whether or not there is a defect in the arrangement of the fins 20 of the heat exchanger 2. The data stored in the storage unit 141 is reference data, which will be described later. The input unit 142 receives an electric signal output by the photodiode amplifier 132, and outputs the input electric signal to the determination unit 143. The determination unit 143 uses the electric signal output by the input unit 142 and the reference data stored in the storage unit 141 to determine whether or not there is a defect in the arrangement of the fins 20 of the heat exchanger 2, and outputs the determination result to the output unit 144 as output data.

[0021] The output unit 144 outputs the output data to the display device 15. The output data is, for example, data indicating whether there is a defective portion in the arrangement of the fins 20. Alternatively, the output data may include data indicating a portion where the arrangement of the fins 20 is defective.

[0022] The display device 15 includes at least one of a speaker 151, an indicator light 152, and a display 153, for example. The speaker 151 notifies the operator of the result of the determination made by the determination unit 143 by voice, buzzer, or music. The indicator light 152 indicates the result of the determination made by the determination unit 143 by the color or operation of a lamp. The operation of the indicator light 152 is, for example, blinking, turning on, or turning off. The indicator light 152 can indicate the state of the appearance inspection device 1 in addition to the determination result, and can notify the operator that, for example, appearance is being determined, the device is on standby, or the device is in an abnormal state. The display 153 displays the portion of the fin 20 where the arrangement is poor with coordinates (xn, yn) on the XY plane based on the determination result, and notifies the operator of the portion of the fin 20 where the arrangement is poor.

[0023] Here, in what cases is there a defect in the arrangement of the fins 20? FIG. 5 is a schematic diagram showing a case where there is no defect in the arrangement of the fins 20 of the heat exchanger 2, that is, a case where the heat exchanger 2 is a non-defective product, and a case where there is a defect in the arrangement of the fins 20 of the heat exchanger 2, that is, a case where the heat exchanger 2 is a defective product. FIG. 5(a) shows the heat exchanger 2. FIG. 5(b) and FIG. 5(c) show the arrangement of the fins 20 when the heat exchanger 2 is viewed from the arrow A in FIG. 5(a). As shown in FIG. 5(b), when the interval between adjacent fins 20 is constant, that is, when there is no defect in the arrangement of the fins 20, the heat exchanger 2 is considered to be a non-defective product. Also, as shown in FIG. 5(c), when adjacent fins 20 are in contact with each other or the fins 20 are continuously fallen, the arrangement of the fins 20 is considered to be defective and the heat exchanger 2 is considered to be a defective product.

[0024] Next, the data indicated by the electrical signal when the heat exchanger 2 is a non-defective product and when it is a defective product will be described. Fig. 6 shows the data indicated by the electrical signal when the heat exchanger 2 is a non-defective product and when it is a defective product. The vertical axis of the graph in Fig. 6 is the voltage value. The horizontal axis is the position of the photodiode 131 in the Y-axis direction.

[0025] Furthermore, since the light is irradiated perpendicularly to the XY plane, the coordinates in the X-axis direction and the Y-axis direction of the position of the light irradiated on the top surface of the heat exchanger 2 are equal to the coordinates in the X-axis direction and the Y-axis direction of the position where the photodiode 131 is disposed. Therefore, the electrical signal shown in Fig. 6 can also be said to be an electrical signal corresponding to the range from coordinates (x, y1) to (x, y1+R) on the top surface of the heat exchanger 2. Note that, in principle with a line light source, the intensity decreases the farther away from the position of the line light source, but this decrease is ignored in Fig. 6.

[0026] FIG. 6(a) shows the arrangement of the fins 20 and the voltage value indicated by the passing light in the Y-axis direction in the case where the heat exchanger 2 is a non-defective product. The light irradiated by the light source 11 to the heat exchanger 2 passes between the adjacent fins 20 and is received by the light receiving unit 13. The photodiode 131 that receives the passing light that passes between the adjacent fins 20 obtains a relatively higher current value than the photodiode 131 that is blocked by the fins 20 and cannot receive the passing light. For this reason, a sharp peak of the electric signal appears at the position where there is a gap formed between the adjacent fins 20, that is, at the position corresponding to the position of the gap in the Y-axis direction. Therefore, if there is no defective part in the arrangement of the fins 20, the electric signal converted from the passing light forms peaks for the number of gaps formed between the adjacent fins 20. Here, the peak means a maximum value that exceeds a predetermined value among the maximum values ​​that appear in the electric signal. Even if there is a maximum, a maximum value that does not exceed a predetermined value is not detected as a peak.

[0027] 6(b) shows the arrangement of the fins 20 and the voltage values ​​indicated by the transmitted light in relation to their positions in the Y-axis direction when the heat exchanger 2 is defective. At least a part of the light irradiated by the light source 11 onto the parts of the heat exchanger 2 where the fins 20 are in contact with each other or onto the parts where the fins 20 are leaning over cannot pass between the adjacent fins 20 and is not received by the light receiving unit 13. In other words, when the fins 20 are poorly arranged, the electrical signal converted from the transmitted light cannot form peaks equal to the number of gaps formed between adjacent fins 20.

[0028] Here, a method of acquiring data indicated by an electrical signal will be described. When the light source 11 is at position x in the X-axis direction, the photodiode amplifier 132 converts the currents output from all the photodiodes 131 into voltages, and outputs the voltage values ​​as electrical signals to the processing device 14. That is, when the light source 11 is at position x in the X-axis direction, electrical signals in the entire range in which the light receiving unit 13 receives light are acquired as data. As a result, when the light source 11 is at position x in the X-axis direction, data used to determine whether the arrangement of the fins 20 is good or bad is acquired. When the position of the light source 11 in the X-axis direction changes, a new electrical signal is output to the processing device 14. For example, when the position of the light source 11 in the X-axis direction changes by the photodiode pitch Px, a new electrical signal is output to the processing device 14. These controls are executed by a data control unit (not shown).

[0029] The processing device 14 extracts an electrical signal corresponding to the photodiode 131 arranged at the position x in the X-axis direction from the electrical signals acquired from the light receiving unit 13, and judges whether the arrangement of the fins 20 is good or bad using the extracted electrical signal. Instead of outputting electrical signals in the entire range in which light is received as data, the light receiving unit 13 may output only an electrical signal read from the photodiode 131 corresponding to the position x in the X-axis direction of the light source 11 as data using a data reading unit (not shown). In this case, the processing device 14 judges whether the arrangement of the fins 20 is good or bad using the electrical signal acquired from the light receiving unit 13 as it is. Moreover, the electrical signal acquired at the position of the heat transfer tube arranged to penetrate the fins 20 is not used to judge whether the arrangement of the fins 20 is good or bad.

[0030] Next, the inspection method will be described. FIG. 7 is a flow chart showing the inspection method using the visual inspection device 1. First, in step S1, the person who performs the inspection prepares a non-defective sample of the heat exchanger 2. Here, the non-defective sample is a sample that shows a case where there is no defective part in the arrangement of the fins 20 of the heat exchanger 2 and is a non-defective product. Next, in step S2, when the light source 11 irradiates the non-defective sample of the heat exchanger 2 fixed by the holding part 12 with light, the judgment part 143 acquires an electric signal. Here, data indicating the electric signal of the non-defective sample is set as reference data. The position of the light source 11 in the X-axis direction when acquiring the reference data does not matter. The reference data is stored in the storage part 141. In step S3, the processing device 14 performs an inspection process on the heat exchanger 2 to be inspected. The visual inspection device 1 performs the inspection process while changing the heat exchanger 2 to be inspected. The inspection process will be described in FIG. 8.

[0031] Next, the operation of the inspection process performed by the visual inspection device 1 will be described. Fig. 8 is a flowchart showing the operation of the inspection process of the visual inspection device 1. In step S11, the holding unit 12 fixes the heat exchanger 2. In step S12, the light source 11 irradiates the heat exchanger 2 with light. In step S13, the light receiving unit 13 converts the transmitted light that has passed between adjacent fins 20 into an electrical signal, and outputs it to the processing device 14 as measurement data.

[0032] In step S14, the determination unit 143 compares the measurement data with the reference data read from the storage unit 141 to determine whether the arrangement of the fins 20 is good or bad. In step S15, the light source control unit determines whether the scanning distance of the light source 11 in the X-axis direction has reached the distance Lx. If the scanning distance of the light source 11 in the X-axis direction has not reached the distance Lx, the light source scanning drive unit moves the position of the light source 11 by a predetermined distance in the +X-axis direction, and the process returns to step S13. If the scanning distance of the light source 11 in the X-axis direction has reached the distance Lx, the process proceeds to step S16. In this way, the appearance inspection device 1 repeatedly performs steps S13 to S14 while changing the position of the light source 11 in the X-axis direction. In step S16, the display device 15 displays the determination result determined by the determination unit 143. Alternatively, the light receiving unit 13 may repeatedly perform step S13 until the scanning distance in the X-axis direction of the light source 11 reaches the distance Lx, and then the determination unit 143 may perform step S14 on the acquired measurement data.

[0033] Next, two examples of the judgment method performed by the judgment unit 143 of the processing device 14 will be described. The judgment unit 143 may make a judgment using both of the two examples. The first method is a judgment method using the number of peaks in the electrical signal. FIG. 9 is a schematic diagram showing the first example of the judgment method performed by the judgment unit 143. FIG. 9(a) shows the judgment range for judging whether or not there is a defect in the arrangement of the fins 20. FIG. 9(b) shows reference data and measurement data when the heat exchanger 2 is defective.

[0034] As shown in Fig. 9(a), the determination unit 143 sets an arbitrary determination range in the Y-axis direction within the range on the heat exchanger 2 where light is irradiated. The size of the determination range in the X-axis direction is 1, and the size in the Y-axis direction is R. The determination unit 143 selects arbitrary coordinates (x1, y1), and sets the range from coordinates (x1, y1) to (x1, y1+R) as the determination range. The determination unit 143 compares the reference data with the measurement data in the determination range. The determination unit 143 performs the determination process while moving the position of the determination range in the Y-axis direction.

[0035] If the arrangement of the fins 20 is defective, a difference occurs between the number of peaks indicated by the reference data and the measurement data, as shown in FIG. 9B. Therefore, the judgment unit 143 calculates the difference ΔN P The formula used by the determining unit 143 for the determination is shown below.

[0036] (Number 1) ΔNP=N P0 -N P < α

[0037] As shown in Equation 1, the difference in the number of peaks, ΔN P If N is smaller than the arbitrarily determined threshold value α, the judgment unit 143 judges that there is no defective portion in the arrangement of the fins 20. P0 is the number of peaks in the reference data in any judgment range. N P is the number of peaks in the measurement data in an arbitrary judgment range. The threshold value α is the allowable value for the difference in the number of peaks. The threshold value α is set arbitrarily, for example, α=0, 1, 2, . . .

[0038] For example, if the judgment unit 143 recognizes the heat exchanger 2 being inspected as a good product only when the number of peaks in the measurement data is the same as the number of peaks in the reference data, the proportion of heat exchangers 2 judged to be good products will decrease. If the threshold value α is increased, the proportion of heat exchangers 2 judged to be good products by the judgment unit 143 will increase, but the possibility that heat exchangers 2 that should be judged to be defective will be judged to be good products will also increase. Furthermore, the larger the size R of the judgment range is, the fewer the number of judgments made by the judgment unit 143. Therefore, the threshold value α and the size R of the judgment range are set in accordance with the quality standard.

[0039] Next, the second method will be described. The second method is a method of making a judgment using a peak-to-peak distance, which is the distance between peaks in an electrical signal. As with the first method, the judgment unit 143 sets an arbitrary judgment range and compares the reference data and the measured data in the judgment range. In addition, the judgment unit 143 performs a judgment process while moving the position of the judgment range in the Y-axis direction. FIG. 10 is a schematic diagram showing a second example of the judgment method performed by the judgment unit 143.

[0040] 10(a) shows the reference data. The judgment unit 143 determines the standard pitch P from the average value of the peak-to-peak distances of the reference data. S The determination unit 143 calculates the standard pitch P from the average value of p1 to p8 shown in FIG. S The determination unit 143 calculates the standard pitch P S may be substituted with the value of the fin pitch defined by the drawing standard. S Alternatively, a previously calculated value may be stored in the storage unit 141.

[0041] 10(b) shows the measurement data when the heat exchanger 2 is defective. As shown in FIG. 10(b), the measurement data when there is a defective arrangement of the fins 20 shows that the peak-to-peak distance is smaller than the standard pitch P S The judgment unit 143 judges whether the standard pitch P S and the measurement pitch P, which is the distance between individual peaks obtained from the measurement data. N If the difference exceeds an arbitrarily determined threshold G, the heat exchanger 2 being inspected is determined to be defective.

[0042] (Number 2) ΔP = P N -P S < G

[0043] As shown in Equation 2, the measured pitch P obtained from the measurement data N and standard pitch P SIf the difference between the measured value and the measured value is smaller than an arbitrarily determined threshold value G, the judgment unit 143 judges the heat exchanger 2 to be inspected to be a non-defective product. S is the average value of the peak-to-peak distance of the standard data or the fin pitch value specified in the drawing standard. N is the peak distance obtained from the measurement data. N may be the average value of the individual peak-to-peak distances obtained from the measurement data. The threshold G is an arbitrarily determined threshold, which is a tolerance for the difference in the peak-to-peak distances.

[0044] For example, if the threshold G is 0, P N and P S If the judgment unit 143 recognizes the heat exchanger 2 to be inspected as a non-defective product only when these values ​​are equal, the proportion of heat exchangers 2 judged to be non-defective products will decrease. If the threshold value G is increased, the proportion of heat exchangers 2 judged to be non-defective products by the judgment unit 143 will increase, but the possibility that heat exchangers 2 that should be judged to be defective will be judged to be non-defective products will also increase. Therefore, the threshold value G is set in accordance with the quality standard.

[0045] Next, a description will be given of the hardware configuration of the processing device 14. Fig. 11 is a hardware configuration diagram of the processing device 14. The processing device 14 is composed of an arithmetic unit 3, a storage device 4, an input device 5, an auxiliary storage device 6, an output device 7, and a signal line 8.

[0046] The processing performed by the processing device 14 can be realized by, for example, the arithmetic device 3. The arithmetic device 3 realizes the functions of the processing device 14 by reading out a necessary program from the auxiliary storage device 6 and executing the processing. The arithmetic device 3 is, for example, a processor, and the processor is an IC (Integrated Circuit) that performs arithmetic processing. Specific examples of the processor are a CPU (Central Processing Unit), a DSP (Digital Signal Processor), and a GPU (Graphics Processing Unit). In addition, it may be a personal computer, a microcomputer board, or an FPGA (Field Programmable Gate Array) board.

[0047] The storage device 4 is a main storage device of the processing device 14. The main storage device temporarily stores calculations of the processing performed by the arithmetic device 3. For example, the storage device 4 is a RAM (Random Access Memory).

[0048] The input device 5 has the function of the input unit 142. The input device 5 inputs an electric signal to the arithmetic unit 3. The input device 5 is an input interface of the processing unit 14.

[0049] The auxiliary storage device 6 has the function of the storage unit 141 and is an auxiliary storage device of the processing device 14. For example, the auxiliary storage device 6 stores initial value data, programs, error logs, reference data, and the like required for the operation of the processing device 14. For example, the auxiliary storage device 6 is a ROM (Read Only Memory), an HDD (Hard Disk Drive), or an SSD (Solid State Drive).

[0050] The output device 7 has a function of the output unit 144. The output device 7 outputs output data to the display device 15. The output device 7 is an output interface of the processing device 14.

[0051] The signal line 8 is a transmission path for transmitting and receiving data between the components shown in FIG.

[0052] Next, a method for manufacturing the heat exchanger 2 will be described. FIG. 12 is a flow chart showing a method for manufacturing the heat exchanger 2. First, in step S100, the fins 20 and the heat transfer tubes are manufactured from a material. Next, in step S200, a heat exchanger core is created by inserting the heat transfer tubes into the fins 20. Next, in step S300, an inspection is performed on this heat exchanger core. Note that the inspection described in this specification is assumed to be performed on this heat exchanger core. In this specification, the heat exchanger core is referred to as the heat exchanger 2. Finally, in step S400, if the processing device 14 determines that the arrangement of the fins 20 is good, brazing is performed to connect the heat exchanger core and the refrigerant distributor with piping.

[0053] According to the appearance inspection device of the first embodiment, the light receiving unit 13 converts the transmitted light that passes between adjacent fins 20 out of the light irradiated onto the heat exchanger 2 into an electrical signal, and the processing device 14 judges whether the arrangement of the fins 20 is good or bad from the peak indicated by the electrical signal exceeding a predetermined value. Therefore, the light source 11 can be placed either above or below the heat exchanger 2, and the light receiving unit 13 can be placed at the other position, thereby reducing the number of parts in the appearance inspection device 1.

[0054] In addition, the appearance inspection device described in Patent Document 1 acquires an image of the heat exchanger 2 with a CCD camera and processes the image. The appearance inspection device described in Patent Document 1 acquires only surface information of the heat exchanger 2, and does not acquire internal information of the heat exchanger 2. For this reason, the appearance inspection device described in Patent Document 1 cannot determine whether there is a defective part in the arrangement of the fins 20 when the fins are bent halfway in the Z direction. However, the appearance inspection device 1 of the present application performs appearance inspection using light that has passed between adjacent fins 20, so that it can determine whether there is a defective part in the arrangement of the fins 20 even when the fins are bent halfway in the Z direction.

[0055] Furthermore, the visual inspection device described in Patent Document 1 performs Fourier transform and the like when performing inspection. However, the visual inspection device 1 of the present application determines that there is a defective portion in the fin arrangement when the number of peaks in the electrical signal corresponding to a predetermined range of the fin falls below a predetermined number of peaks or when the peak-to-peak distance between peaks exceeds a predetermined peak-to-peak distance. This makes it possible to reduce the processing load when performing visual inspection.

[0056] In addition, as long as the fins 20 are arranged regularly, instead of arranging plate-shaped fins 20 at regular intervals, bellows-shaped fins 20 may be arranged regularly. In this case, the heat transfer tube is not arranged to penetrate the fins 20, but the folded-back portion of the bellows-shaped fins 20 is attached to the surface of the heat transfer tube.

[0057] Variation 1. 13 is a schematic diagram showing a state in which heat exchanger 2 is placed on holding unit 12 in Modification 1 of Embodiment 1. In Embodiment 1, a case has been described in which holding unit 12 includes reference block 121 and clamp 122, and heat exchanger 2 is clamped between reference block 121 and clamp 122. In the modification, a case will be described in which holding unit 12 includes holding stage 123 instead of reference block 121 and clamp 122, and heat exchanger 2 is placed on holding stage 123.

[0058] The holding stage 123 is a plate-like body on which the heat exchanger 2 is placed. The holding stage 123 transmits the light irradiated by the light source 11 to the heat exchanger 2. The holding stage 123 is formed using a material with high light transmittance. The material with high light transmittance is, for example, acrylic or polycarbonate. When the heat exchanger 2 is placed on the holding stage 123, the origin may be determined by matching the corner of the heat exchanger 2 with an L-shaped contact provided on the holding stage 123, or the origin may be determined by identifying the corner of the heat exchanger 2 using a conventional image recognition technology. After the origin is determined, the light source driving unit may be driven so that the initial position of the light source 11 matches the origin at the start of the appearance inspection.

[0059] The operation of the visual inspection device 1 in the first modification is similar to that in the first embodiment, and therefore a description thereof will be omitted.

[0060] According to the configuration of the first modification, the holding unit 12 includes a holding stage 123, and the heat exchanger 2 is placed on the holding stage 123, so there is no need to clamp the heat exchanger 2 using the reference block 121 and the clamp 122. This allows the appearance inspection device 1 of the first modification to perform inspection without damaging the side surface of the heat exchanger 2.

[0061] It is also possible to use a combination of the reference block 121, the clamp 122, and the holding stage 123 in the first embodiment. In this case, the reference block 121 and the clamp 122 do not clamp the heat exchanger 2 with a force strong enough to damage the side surface of the heat exchanger 2, but rather clamp the heat exchanger 2 with a force strong enough to fix the heat exchanger 2 in place and place the heat exchanger 2 on the holding stage 123, thereby supporting the heat exchanger 2.

[0062] Variation 2. Next, a second modified example of the first embodiment will be described. FIG. 14 is a schematic diagram showing a case where the heat exchanger 2 is fixed by the reference block 121 and the clamp 122, which are the holding unit 12, and then the inspection is performed in the darkroom 9. First, the darkroom 9 will be described. The darkroom 9 is a housing having an opening for inserting and removing the heat exchanger 2. The darkroom 9 also has a door 91 for closing the opening. When the heat exchanger 2 is stored inside the darkroom 9, the door 91 is closed to block light from outside the darkroom 9. The darkroom 9 is composed of a light-shielding plate using a black double-sided acrylic matte plate or the like, and prevents light from outside the darkroom 9 from entering the light-receiving unit 13 during acquisition of measurement data. At least the light source 11 and the light-receiving unit 13, which are components of the appearance inspection device 1, are stored inside the darkroom 9. The processing device 14 and the display device 15 may be stored inside the darkroom 9, but may also be located outside. It is preferable that the display device 15 is located outside the darkroom 9.

[0063] The heat exchanger 2 is moved to the darkroom 9 while being clamped between the reference block 121 and the clamp 122. The force with which the heat exchanger is clamped between the reference block 121 and the clamp 122 at this time is set to a strength that does not cause the position of the heat exchanger 2 to shift during inspection and does not significantly damage the side surface of the heat exchanger 2.

[0064] Heat exchanger 2 clamped by reference block 121 and clamp 122 is detachably installed in a positioning mechanism (not shown) installed in darkroom 9. The positioning mechanism may be, for example, a mechanism that determines the positions at which reference block 121 and clamp 122 are to be installed, and may be a recess for installing reference block 121 and clamp 122. When reference block 121 and clamp 122 are installed in the positioning mechanism, heat exchanger 2 is placed in a predetermined position between light source 11 and light receiving unit 13 in darkroom 9, so that appearance inspection can be performed using appearance inspection device 1 as in the first embodiment.

[0065] According to the configuration of the second modification, since external light is blocked in the darkroom 9, it is possible to carry out the visual inspection of the heat exchanger 2 without considering the influence of external light.

[0066] The person who performs the inspection may perform the inspection by offsetting the influence of external light without performing the inspection in the darkroom 9. The offset means that the electrical signal derived from external light acquired in a state where light is not irradiated by the light source 11 is removed from the electrical signal indicating the measurement data before the judgment unit 143 makes a judgment. FIG. 15 is a schematic diagram showing the difference in peaks indicated by the electrical signal when the darkroom 9 is used and when it is not used. The vertical axis indicates the voltage value. The horizontal axis indicates the position in the Y-axis direction in an arbitrary judgment range determined by the judgment unit 143. FIG. 15(a) shows the voltage value when the inspection of a non-defective sample is performed in the darkroom 9. FIG. 15(b) shows the voltage value when the inspection of a non-defective sample is performed outside the darkroom 9. As shown in FIG. 15(a) and FIG. 15(b), even if the inspection is performed using the same non-defective sample, a voltage value difference V' occurs due to the influence of light outside the darkroom 9, so when the appearance inspection is performed outside the darkroom 9, it is necessary to remove the voltage value difference V' from the electrical signal indicating the measurement data. When a green laser is used for light source 11, if the illuminance is 300 to 700 lux, which is typical in factories, it is possible to make a sufficient determination even if the influence of external light is offset.

[0067] Embodiment 2 16 is a schematic diagram showing how the visual inspection device 1 in the second embodiment inspects the heat exchanger 2. The second embodiment differs from the first embodiment in the light source 11, the light receiving unit 13, and the method of acquiring data indicated by an electrical signal. Only the parts that differ from the first embodiment will be described, and the description of the similar parts will be omitted as appropriate.

[0068] The light source 11 in the second embodiment is not the line light source in the first embodiment, but a point light source 111. Here, a point light source means a light source whose light-emitting part has a very small area and is close to a point. The point light source 111 is realized, for example, by a point light source LED. A point light source LED has an even smaller area of ​​a light-emitting part than a general LED, making it point-like. A general LED emits light over one surface of the chip, whereas a point light source LED emits light from a very small portion of one surface of the chip.

[0069] The point light source 111 is scanned in the X-axis direction and the Y-axis direction by a point light source scanning drive unit (not shown). The point light source 111 is scanned while maintaining a constant distance from the heat exchanger 2. The distance Lx [m] over which the light source 111 is scanned in the X-axis direction is equal to or greater than the length Wx [m] of the heat exchanger 2 in the X-axis direction. The distance LLy [m] over which the light source 111 is scanned in the Y-axis direction is equal to or greater than the length Dy [m] of the heat exchanger 2 in the Y-axis direction.

[0070] The light receiving unit 13 includes a photodiode 131 arranged corresponding to the range where the point light source 111 irradiates light. Here, the range where the point light source 111 irradiates light means, for example, the range where the light source 111 can irradiate light when the light source 111 is stopped. The number of photodiodes 131 may be one or may be two or more, as long as it can correspond to the range where the point light source 111 irradiates light. The photodiode 131 is scanned in the X-axis direction and the Y-axis direction in synchronization with the point light source 111 by a light receiving unit scanning drive unit not shown. The light receiving unit 13 is scanned while keeping the distance from the heat exchanger 2 constant.

[0071] The operation of the visual inspection apparatus 1 in the second embodiment differs only in the method of acquiring data indicated by an electrical signal, so only the method of acquiring data indicated by an electrical signal will be described.

[0072] When the point light source 11 is at position x in the X-axis direction and position y in the Y-axis direction, the photodiode amplifier 132 converts the currents output from all the photodiodes 131 into voltages and outputs the voltage values ​​as electrical signals to the processing device 14. When the position of the point light source 111 moves a predetermined distance in the +X-axis direction or +Y-axis direction, a new electrical signal is output to the processing device 14. The processing device 14 stores the acquired electrical signals in the storage unit 141.

[0073] The distance that the point light source 111 moves in the Y-axis direction from when the processing device 14 acquires an electrical signal until when the processing device 14 acquires the next electrical signal is smaller than half the length of the fin pitch P [m]. The distance that the point light source 111 moves in the X-axis direction from when the processing device 14 acquires an electrical signal until when the processing device 14 acquires the next electrical signal does not have to be smaller than the fin pitch P [m]. However, a smaller moving distance allows more electrical signals to be acquired than a larger moving distance, and therefore the inspection accuracy can be improved.

[0074] The processing device 14 generates an electrical signal corresponding to the position x from the electrical signals acquired from the light receiving unit 13 while the position of the point light source 111 in the X-axis direction is position x and the scanning distance of the point light source 111 in the Y-axis direction reaches the distance LLy, and judges whether the arrangement of the fin 20 is good or bad using the generated electrical signal. When there are two or more photodiodes, the processing device 14 may, for example, take the average value or maximum value of the electrical signals as the electrical signal corresponding to the position where the electrical signal was acquired. The method of judgment performed by the processing device 14 is the same as in the first embodiment. The inspection process performed by the processing device 14 is the same as in the first embodiment.

[0075] According to the appearance inspection device 1 in embodiment 2, it is equipped with a point light source 111 and a light receiving section 13 having a number of photodiodes 131 corresponding to the area illuminated by the point light source 111, so that the appearance inspection device 1 can be made smaller than that of embodiment 1.

[0076] In the second embodiment, the case where the light source 11 is a point light source 111 has been described, but the light source 11 may be a line light source. In this case, the light receiving unit 13 includes a photodiode 131 arranged corresponding to the range where the line light source irradiates light, and the light source 11 and the light receiving unit 13 are scanned synchronously only in the X-axis direction.

[0077] In the second embodiment, the light receiving unit 13 including the photodiode 131 arranged corresponding to the range irradiated by the point light source 111 has been described, but the light receiving unit 13 may include the photodiode 131 arranged corresponding to the inspection range of the heat exchanger 2. In this case, the light receiving unit 13 is not scanned in the X-axis and Y-axis directions, and only the light source 11 is scanned in the X-axis and Y-axis directions.

[0078] Various aspects of the present disclosure are summarized below as appendices.

[0079] (Appendix 1) a light source that irradiates light onto a heat exchanger having a plurality of fins arranged at predetermined intervals; a light receiving section that receives light that has passed between adjacent fins, converts the light into an electrical signal, and outputs the electrical signal; a processing device that judges whether the arrangement of the fins is good or bad based on the peak of the electrical signal; A visual inspection device for a heat exchanger comprising: (Appendix 2) The processing device determines that there is a defective portion in the arrangement of the fins when the number of the peaks in the electrical signal corresponding to the predetermined range of the fins falls below a predetermined number of peaks or when the peak-to-peak distance between the peaks exceeds a predetermined peak-to-peak distance. 2. An appearance inspection device for a heat exchanger according to claim 1. (Appendix 3) A holding portion that holds and fixes the heat exchanger is provided. An appearance inspection device for a heat exchanger according to claim 1 or 2. (Appendix 4) A plate-like body on which the heat exchanger is placed has a holder that transmits the light emitted by the light source. 4. An appearance inspection device for a heat exchanger according to claim 1. (Appendix 5) The processing device removes the electrical signal output by the light receiving unit when the light source is not irradiating the light from the electrical signal converted by receiving the passing light before the processing device makes a judgment. 5. An appearance inspection device for a heat exchanger according to any one of claims 1 to 4. (Appendix 6) The light source is a line light source, and is scanned by a light source scanning drive unit while keeping the distance from the heat exchanger constant. 6. An appearance inspection device for a heat exchanger according to any one of claims 1 to 5. (Appendix 7) The light source is a point light source, and is scanned by a point light source scanning drive unit while keeping the distance from the heat exchanger constant. 6. An appearance inspection device for a heat exchanger according to any one of claims 1 to 5. (Appendix 8) The light receiving unit includes a photodiode arranged in correspondence with an inspection range of the heat exchanger. 8. An appearance inspection apparatus according to claim 1, (Appendix 9) the light receiving unit includes a photodiode disposed in correspondence with an area to which the light source irradiates the light, The photodiode is scanned by a light receiving unit scanning drive unit in synchronization with the scanning of the light source while keeping the distance from the heat exchanger constant. 8. An appearance inspection apparatus according to claim 1, (Appendix 10) A step of irradiating light from a light source onto a heat exchanger having a plurality of fins arranged at predetermined intervals; a step of receiving, by a light receiving unit, light passing between adjacent fins among the light, and converting the light into an electrical signal; a step of determining whether the arrangement of the fins is good or bad from a peak indicated by the electrical signal by a processing device; a step of connecting the heat exchanger and a refrigerant distribution line with a pipe when the processing device determines that the arrangement of the fins is good; A method for manufacturing a heat exchanger comprising the steps of: (Appendix 11) A step of irradiating light from a light source onto a heat exchanger having a plurality of fins arranged at predetermined intervals; a step of receiving, by a light receiving unit, light passing between adjacent fins among the light, and converting the light into an electrical signal; a step of determining whether the arrangement of the fins is good or bad from a peak indicated by the electrical signal by a processing device; A method for inspecting a heat exchanger comprising: [Explanation of symbols]

[0080] 1 Appearance inspection device, 2 Heat exchanger, 3 Calculation device, 4 Memory device, 5 Input device, 6 Auxiliary memory device, 7 Output device, 8 Signal line, 9 Darkroom, 11 Light source, 12 Holding unit, 13 Light receiving unit, 14 Processing unit, 15 Display device, 20 Fin, 91 Door 111 Point light source, 121 Reference block, 122 Clamp, 123 Holding stage, 131 Photodiode, 132 Photodiode amplifier, 141 Memory unit, 142 Input unit, 143 Judgment unit, 144 Output unit, 151 Speaker, 152 Indicator light, 153 Display

Claims

1. a light source that irradiates light onto a heat exchanger having a plurality of fins arranged at predetermined intervals; a light receiving section that receives light that has passed between adjacent fins, converts the light into an electrical signal, and outputs the electrical signal; a processing device that judges whether the arrangement of the fins is good or bad based on the peak of the electrical signal; A visual inspection device for a heat exchanger comprising:

2. The processing device determines that there is a defective portion in the arrangement of the fins when the number of the peaks in the electrical signal corresponding to the predetermined range of the fins falls below a predetermined number of peaks or when the peak-to-peak distance between the peaks exceeds a predetermined peak-to-peak distance. The visual inspection device for a heat exchanger according to claim 1.

3. A holding portion that holds and fixes the heat exchanger is provided.

3. The visual inspection device for a heat exchanger according to claim 1 or 2.

4. A plate-like body on which the heat exchanger is placed has a holder that transmits the light emitted from the light source.

3. The visual inspection device for a heat exchanger according to claim 1 or 2.

5. The processing device removes the electrical signal output by the light receiving unit when the light source is not irradiating the light from the electrical signal converted by receiving the passing light before the processing device makes a judgment.

3. The visual inspection apparatus according to claim 1 or 2.

6. The light source is a line light source, and is scanned by a light source scanning drive unit while keeping the distance from the heat exchanger constant. The visual inspection apparatus according to claim 1 or 2.

7. The light source is a point light source, and is scanned by a point light source scanning drive unit while keeping the distance from the heat exchanger constant. The visual inspection apparatus according to claim 1 or 2.

8. The light receiving unit includes a photodiode arranged in correspondence with an inspection range of the heat exchanger.

8. The visual inspection apparatus according to claim 6 or 7.

9. the light receiving unit includes a photodiode disposed in correspondence with an area to which the light source irradiates the light, The photodiode is scanned by a light receiving unit scanning drive unit in synchronization with the scanning of the light source while keeping the distance from the heat exchanger constant.

8. The visual inspection apparatus according to claim 6 or 7.

10. A step of irradiating light from a light source onto a heat exchanger having a plurality of fins arranged at predetermined intervals; a step of receiving, by a light receiving unit, light passing between adjacent fins among the light, and converting the light into an electrical signal; a step of determining whether the arrangement of the fins is good or bad from a peak indicated by the electrical signal by a processing device; a step of connecting the heat exchanger and a refrigerant distributor with piping when the processing device determines that the arrangement of the fins is good; A method for manufacturing a heat exchanger comprising the steps of:

11. A step of irradiating light from a light source onto a heat exchanger having a plurality of fins arranged at predetermined intervals; a step of receiving, by a light receiving unit, light passing between adjacent fins among the light, and converting the light into an electrical signal; a step of determining whether the arrangement of the fins is good or bad from a peak indicated by the electrical signal by a processing device; A visual inspection method for a heat exchanger, comprising:

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