JP2014119431A - Crack detection device and method in heat exchanger tank assembling process - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and accurately detect a crack of a tank in a heat exchanger tank assembling process.SOLUTION: The detection device 20 detects a crack of the tank 3 in a heat exchanger tank assembling process of pressing a resin-made tank 3 to a plate 2 supported by a rail 11 via an O-ring 4 and crimping a crimping allowance 2e of the plate 2 and fixing the tank 3 to the plate 2. The detection device 20 includes: a sensor 21 that is attached to the rail 11 and measures the sound pressure; and a computer 22 for detecting that a crack occurs in the tank 3 in the assembling process on the basis of a sound pressure level as the magnitude of the sound pressure measured during the assembling process.

Description

  The present invention relates to a technique for detecting cracks in a tank generated in a heat exchanger tank assembly process.

  The tank (upper tank and lower tank) of the heat exchanger is fixed to a plate connected to ends of a plurality of tubes extending in the vertical direction. The tank is fixed by placing an O-ring on the outer periphery of the plate in order to make the tank airtight, and crimping the end of the plate in a state where the O-ring is compressed by the tank (Patent Documents 1 and 2). ).

JP-A-55-76207 JP 63-242428 A

  If the tank is made of resin, cracks may occur in the tank during the tank assembly process. Cracking of the tank occurs due to various causes. When the relative position between the tank and the plate shifts and the tank and the plate interfere with each other, or when the stroke when pressing the tank against the O-ring is excessive, the plate is supported. If the tool is improper, if the punch for pressing against the end of the plate (see Fig. 2) is too long and the punch and the tank interfere with each other, the end of the plate is too long or the tank is improperly caulked. This occurs when the end of the plate that has been inserted bites into the tank or when the punch interferes with a portion other than the end of the plate due to a positioning error or the like.

  For this reason, an airtight test is performed after the tank is assembled, but in the airtight test, if the crack does not penetrate the tank, the airtightness in the tank is maintained, and it cannot be determined that there is an abnormality, so that the crack has occurred. It cannot be detected. Such cracks that do not penetrate the tank may develop into cracks that penetrate the tank after entering the market, and must be detected by inspection prior to shipment.

  In view of this, it is conceivable to determine whether or not a crack has occurred in the tank by measuring the sound pressure and vibration at the time of the crack with a sensor and determining based on this. However, it is not easy to attach a sensor to a tank having a curved surface, and the sensor needs to be attached and detached every time one tank is inspected, making it difficult to inspect efficiently.

  The present invention has been made in view of such technical problems, and it is an object of the present invention to easily and accurately detect cracks in a tank in a heat exchanger tank assembly process.

  According to an aspect of the present invention, a tank assembly for a heat exchanger that presses a resin tank against a plate supported by a support member via a seal member, and crimps an end of the plate to fix the tank to the plate. A detection device for detecting cracks in the tank in a process, which is attached to the support member and measures sound pressure or vibration, and based on the magnitude of sound pressure or vibration measured during the assembly process And a computer for detecting the occurrence of cracks in the tank in the assembling step.

  Moreover, the detection method is provided.

  According to these aspects, in addition to being able to detect the occurrence of a crack regardless of whether or not the crack penetrates the tank, the sensor is attached to the support member instead of the tank, so that it is easy and accurate. Can be detected.

  In other words, since the sensor is fixed to the support member, not the tank, it is easy to attach the sensor, and even when the inspection of one tank is completed and another tank is inspected, there is no need to change the sensor. Absent.

  The sound pressure or vibration is measured in a state where the tank is pressed, that is, in a state where the tank, the seal member, and the support member are in close contact with each other. As a result, attenuation when the sound pressure or vibration generated when the tank breaks is transmitted to the support member is suppressed, and the sound pressure or vibration when the tank breaks can be accurately measured, and the crack of the tank is high. It can be detected with accuracy.

It is a schematic block diagram of the assembly | attachment apparatus of the tank for heat exchangers provided with the detection apparatus which concerns on embodiment of this invention. It is an enlarged view of a caulking part. It is the flowchart which showed the detection procedure of the crack of the tank by a computer. It is a figure which shows an example of the sound pressure measured by a sensor. It is the figure which showed an example of the sound pressure level for every frequency obtained by frequency analysis.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 shows a schematic configuration of a heat exchanger tank assembly apparatus.

  The assembling apparatus 10 is an apparatus for assembling a resin heat exchanger tank 3 to a metal plate 2 in which ends of a plurality of tubes 1 are brazed and joined. The assembling apparatus 10 includes a pair of rails 11 and a pressing member 12 that can be moved up and down by a cylinder (not shown).

  The rail 11 is a plate-like member erected on a base member (not shown), and is disposed on both sides of the tube 1.

  The plate 2 is placed on the rail 11. A concave groove 2g is formed in the plate 2 along the outer periphery of the plate 2, and an O-ring 4 is attached to the concave groove 2g. The end of the plate 2 is a caulking allowance 2e that is folded inward during caulking. The O-ring 4 is in contact with the lower end 3e of the tank 3 bent in an L shape.

  When the pressing member 12 is lowered in such a state, the tank 3 is pressed against the plate 2 via the O-ring 4. Since the plate 2 is supported by the rail 11, the O-ring 4 is compressed between the lower end 3 e of the tank 3 and the plate 2.

  Then, as shown in FIG. 2, when the punch 13 is pressed against the caulking allowance 2 e from the side and the caulking allowance 2 e is bent inward as indicated by a broken line, the tank 3 is caulked and fixed to the plate 2.

  The assembling device 10 is provided with a detecting device 20 that detects cracks in the tank 3 in the tank assembling step. The detection device 20 includes a sensor 21 that measures the sound pressure that is fixed to the side surface of the rail 11 and is transmitted to the rail 11, and a computer 22 that processes a measurement signal of the sensor 21. The computer 22 detects the occurrence of cracks in the tank 3 based on the measurement result of the sensor 21 as described below.

  FIG. 3 shows a procedure for detecting cracks in the tank 3 by the computer 22. The procedure for detecting cracks in the tank 3 will be described with reference to this.

  First, the computer 22 measures the sound pressure by the sensor 21 from the start to the end of the tank assembly process (S1). FIG. 4 shows an example of the sound pressure measured at that time.

  Next, the computer 22 searches for the time when the sound pressure reaches its peak from the measurement result in S1, and the sound pressure around the time when the sound pressure reaches its peak (a predetermined time centered on the time when the sound pressure reaches its peak). Extract the measurement results. FIG. 4 shows an example of the measurement result of S1, and in this example, the measurement result of the portion surrounded by A including the peak sound pressure is extracted.

  Next, the computer 22 performs frequency analysis (for example, fast Fourier transform) on the extracted measurement result to obtain a sound pressure level for each frequency. The sound pressure level represents the magnitude of the sound pressure, and is a value obtained by multiplying the common logarithm of the ratio between the measured sound pressure and the reference value by 20 times. FIG. 5 shows the result of frequency analysis of the portion surrounded by A in FIG.

  Next, the computer 22 determines whether the sound pressure level of the specific frequency exceeds the threshold value based on the result of the frequency analysis (S4). The specific frequency is a value determined by the material of the tank 3. This is because the frequency of the sound generated when a crack occurs in the tank 3 mainly depends on the material of the tank 3, and if the material is the same, the sound having the same frequency is generated even if the crack occurrence site and the cause of occurrence are different. This is because. Further, the threshold value is set to a value that can be determined to be a sound pressure level caused by cracks in the tank 3, and is set to a value that is larger than the upper limit of the sound pressure level that can be taken when no cracks occur in the tank 3. The

  When the sound pressure level at the specific frequency exceeds the threshold value, the computer 22 determines that the tank 3 has been cracked in the tank assembly process (S5). Otherwise, the computer 22 determines that the tank 3 is not cracked in the tank assembly process (S6).

  Therefore, according to this detection device 20, in addition to being able to detect the occurrence of cracks in the tank 3 regardless of whether or not the cracks generated during assembly pass through the tank 3, the sensor 21 is not the tank 3. By attaching to the rail 11, there exists an effect that it can detect easily and accurately.

  That is, since the sensor 21 is fixed to the rail 11 instead of the tank 3, the sensor 21 can be easily attached, and the inspection of one tank 3 is completed and another tank is inspected. There is no need to replace the sensor 21.

  The sound pressure is measured in a state where the tank 3 is pressed by the pressing member 12, that is, in a state where the tank 3, the O link 4 and the rail 11 are in close contact. Thereby, the attenuation when the sound generated when the tank 3 breaks is transmitted to the rail 11 can be suppressed, the sound pressure when the tank 3 breaks can be accurately measured, and the crack of the tank 3 can be accurately detected. Can be detected.

  The embodiment of the present invention has been described above, but the above embodiment is merely a part of an application example of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. is not.

  For example, in the above embodiment, the sound pressure is measured by the sensor 21, but a minute vibration (acceleration) when the tank 3 breaks is measured by the sensor 21, and the crack of the tank 3 is detected based on the magnitude. You may do it.

  The sensor 21 may be attached to a base member (not shown) on which the rail 11 is erected instead of the rail 11.

1 Assembly device 2 Plate 2e Caulking allowance (end)
3 Tank 4 O-ring (seal member)
20 detector 21 sensor 22 computer

Claims (6)

A tank made of resin is pressed against a plate supported by a support member through a seal member, and a crack of the tank is detected in a heat exchanger tank assembly process in which the end of the plate is crimped to fix the tank to the plate. A detection device,
A sensor attached to the support member for measuring sound pressure or vibration;
Based on the sound pressure or vibration magnitude measured during the assembly process, a computer that detects that the tank has cracked in the assembly process;
A detection device comprising: The detection device according to claim 1,
The computer frequency-analyzes the sound pressure or vibration measured during the assembly process, and when the sound pressure or vibration magnitude of a specific frequency exceeds a threshold value, the tank cracks in the assembly process. Detect what happened,
A detection device characterized by that. The detection device according to claim 2,
The specific frequency is a value determined according to the material of the tank.
A detection device characterized by that. A tank made of resin is pressed against a plate supported by a support member through a seal member, and a crack of the tank is detected in a heat exchanger tank assembly process in which the end of the plate is crimped to fix the tank to the plate. A detection method,
Measure the sound pressure or vibration transmitted from the tank to the support member,
Based on the sound pressure or vibration magnitude measured during the assembly process, it is detected that the tank has cracked in the assembly process.
A detection method characterized by that. The detection method according to claim 4,
The frequency of sound pressure or vibration measured during the assembly process is analyzed, and when the sound pressure or vibration magnitude at a specific frequency exceeds a threshold value, the tank is cracked in the assembly process. Detect
A detection method characterized by that. The detection method according to claim 5,
The specific frequency is a value determined according to the material of the tank.
A detection method characterized by that.

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