JP2020008284A - Blister tester and test method - Google Patents

Abstract

To provide a blister tester and a blister test method with which it is possible to conduct operation and management easily and safely, which is environmentally friendly, and the inspection time of which is relatively short.SOLUTION: A blister tester 1 comprises an IH coil 2 in which a sample SA is placed, and control means for adjusting the output of the IH coil 2. The control means adjusts the output of the IH coil 2 to a prescribed output and thereafter to a specific output lower than the prescribed output, and repeats this. Preferably, the specific output is 0 and the output of the IH coil 2 is intermittently turned on and off.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a blister tester and a blister test method executable in the blister tester.

Gas may be contained in the casting due to entrainment of air or decomposed gas of the release material during the casting process of the casting such as die casting.
In order to check the state of such a gas, a blister tester is used in which a gas of a casting sample is exposed as a blister by heating or molten salt. The gas in the casting is inspected by the state (number, etc.) of the blisters in the sample subjected to the blister tester.
A general hot blast stove is used as a heating blister tester. In this case, heating for about 30 minutes or more is necessary, depending on the material and size of the sample, in order to sufficiently reveal the blister.
On the other hand, as a blister tester using a molten salt, one described in Japanese Utility Model Registration No. 3009463 (Patent Document 1) is known. In this case, the sample is uniformly heated in a short time by immersing it in a molten salt (a salt bath formed by heating and melting nitrate), and a blister appears in a short time.

Utility model registration No. 3009463

In the above-described blister tester using a molten salt, since the molten salt is used, careful handling of the molten salt is required, and operation and management are troublesome.
Further, it is necessary to discharge the vaporized molten salt, which may affect the environment.
Further, when water adheres to the sample, if the conditions are met, steam explosion may occur due to the reaction between the molten salt and water, and there is a possibility of explosion due to decomposition of the molten salt itself.

  Therefore, a main object of the present invention is to provide a blister test machine and a blister test method that can be easily and safely operated and managed, are environmentally friendly, and have a relatively short inspection time.

The invention according to claim 1 includes, in a blister tester, a coil in which a sample is arranged, and control means for adjusting an output of the coil, wherein the control means controls an output of the coil. After the predetermined output, the specific output smaller than the predetermined output is repeated.
The invention according to claim 2 is characterized in that, in the above invention, the specific output is 0.
According to a third aspect of the present invention, in the above-mentioned invention, the control means determines that the predetermined output is higher than the temperature of the sample or the temperature around the sample before reaching the softening point of the sample. After that, it is characterized by being lowered.
According to a fourth aspect of the present invention, in the above-mentioned invention, a distance between the sample and the coil is 32 mm or more.
According to a fifth aspect of the present invention, in the blister test method, a state in which the induction heating by the coil is repeatedly performed on the sample after the output of the coil is set to a predetermined output and then to a specific output lower than the predetermined output. The sample is heated to a temperature equal to or higher than the softening point and lower than the melting point.
According to a sixth aspect of the present invention, in the above-mentioned invention, the specific output is 0.
According to a seventh aspect of the present invention, in the above-mentioned invention, the predetermined output is made lower after the temperature of the sample or the temperature around the sample before reaching the softening point of the sample. It is characterized by the following.
According to an eighth aspect of the present invention, in the above-mentioned invention, a distance between the sample and the coil is 32 mm or more.

  A primary advantage of the present invention is that a blister tester and method are provided that are easier and safer to operate and manage, are more environmentally friendly, and have a relatively shorter inspection time.

It is a schematic diagram of a blister test machine according to the present invention. It is a flow chart about an example of operation of a blister test machine concerning the present invention, and an example of a blister test method. 5 is a graph showing power (left vertical axis) and total power (right vertical axis) with respect to elapsed time (horizontal axis) from the start of the test. 5 is a graph showing various temperatures (vertical axis) with respect to an elapsed time (horizontal axis) from the start of the test.

Hereinafter, examples of embodiments according to the present invention, together with modifications thereof, will be described based on the drawings as appropriate.
In addition, this form is not limited to the following examples and modified examples.

FIG. 1 is a schematic diagram of a blister tester 1 according to the present invention.
The blister testing machine 1 inspects a sample SA of a die-cast product cast by the ADC 12, which is frequently used as die-cast aluminum. The blister tester 1 can heat the sample SA to about 530 ° C., which is the softening point of the ADC 12.
The sample SA of the product to be inspected may be made of another aluminum alloy, an aluminum magnesium alloy, zinc, or copper. Alternatively, it may be made of an alloy in which at least two of them are combined. Even in these cases, it is possible to similarly heat to a softening point lower than the melting point and close to the melting point.

The blister tester 1 controls an IH coil 2 (coil) for induction heating (IH), an inverter power supply 4 serving as a power supply for the IH coil 2, a matching circuit 6 interposed therebetween, and these. Control means (not shown).
The sample SA is arranged in the IH coil 2.
A cooler (not shown) through which coil cooling water for cooling the IH coil 2 can pass is provided adjacent to the IH coil 2.
Further, a temperature sensor 8 for detecting the temperature of the sample SA is provided. The temperature sensor 8 is here a radiation thermometer, and is electrically connected to the control means.

The control means includes a computer having an information processing means (CPU), a storage means (for example, a memory card), and an input means (for example, at least one of a keyboard and a pointing device).
The storage means is capable of storing various types of information, and stores cycle information relating to the driving power of the IH coil 2. That is, the cycle information indicates a transition of the driving power of the IH coil 2 in a predetermined cycle (here, 20 seconds), and here, the predetermined power (24 kilowatts (kW)) is maintained for a predetermined time (12 seconds). This is a combination of the high power information and the low power information after which the power is reduced to a specific power (0 kW) lower than the predetermined power for a specific time (8 seconds). Since the specific power is 0, the low power information can be said to be off information. Note that the cycle information may switch the power in three or more stages, or may include a plurality of at least one of the large power information and the small power information. Further, the predetermined power may be other than 24 kW, and the specific power may not be 0. Further, the predetermined time may be other than 12 seconds, and the specific time may be other than 8 seconds.
In addition, when the temperature of the sample SA reaches a predetermined temperature (softening point of the sample SA), the storage means reduces the predetermined power related to the large power information to reduce the power for reducing the output of the IH coil 2. Information is stored. Here, the power reduction information is 9.6 kW corresponding to 40% of the predetermined power. The power reduction information may be 30% or more and 50% or less of the predetermined power, or may be 20% or more and 60% or less. Further, in order to reduce the predetermined power in three or more steps, second power reduction information or further third power reduction information may be provided.
The input means accepts a user's input.
The control means may be a control panel or the like installed in place of the computer or together with the computer. Further, the control means may be provided separately in a plurality of members or portions. Further, the input means may be omitted, or a display means capable of displaying various information may be added.

Hereinafter, an operation example of such a blister testing machine 1 and an example of a blister testing method executed by the blister testing machine 1 will be mainly described with reference to FIG.
When the sample SA is set in the IH coil 2 and the user inputs a test start to the control means via the input means, the operation of the blister test machine 1 is started.
Here, the sample SA is an unpainted, disc-shaped die-cast product by the ADC 12, and its weight is about 450 g (gram).

Generally, in order to induction-heat a metal product of about 450 g, that is, about 1 kg (kilogram) or less, which is a large part of a casting, especially a die-cast product, the distance (gap) from the IH coil 2 to the metal product needs to be increased if the gap is too large. Is deteriorated, so that it is set to about 20 mm (mm) to 30 mm.
On the other hand, in the blister test by the blister test machine 1, the gap is increased to 50 mm. The gap may be 32 mm or more, or 35 mm, 40 mm, or 45 mm or more, or 150 mm or less, or 120 mm, 100 mm, or 80 mm or less.

The control means controls the inverter power supply 4 and the matching circuit 6 based on the cycle information, and inductively heats the sample SA with the IH coil 2 (step S1). The output frequency of the IH coil 2 is 10.1 kHz (kilohertz) here, but may be another value.
At first, the control means repeatedly supplies the IH coil 2 with the predetermined power of 24 kW for 12 seconds and then stops the power supply for 8 seconds based on the specific power (0 kW) (intermittent ON / OFF of the IH coil 2). operation). The output of the IH coil 2 becomes a predetermined output by the predetermined power when the intermittent operation is on, and becomes a specific output (output 0) by the specific power when the intermittent operation is off.
Here, in order to investigate the temperature distribution of the sample SA, four temperature sensors 8 are provided for the sample SA. The temperature sensors 8 are located at the vertices of an equilateral triangle on the surface of the disk-shaped sample SA, 4 mm inside the disk circumference. Then, the temperatures of the peripheral portions (first to third portions) and the central portion (fourth portion) are detected. The control means controls the output of the IH coil 2 with reference to the temperature of the second portion of the sample SA, and stores the temperatures at four points. In addition, each temperature sensor 8 for detecting the temperature of the coil cooling water inlet (before cooling) and the temperature of the coil cooling water outlet (after cooling), and the temperature sensor 8 for measuring the ambient temperature of the blister tester 1 are provided. The control means also stores the coil cooling water inlet temperature, the coil cooling water inlet temperature, and the ambient temperature.
At least one of the number and arrangement of the temperature sensors 8 may be other than those described above. Further, the temperature referred to in the control by the control means may be any one of the first, third, and fourth portions, may be an average of a combination thereof, or may be a distance from the sample SA. The temperature of a portion (around the sample SA) may be used. Further, at least one of the various temperatures may not be stored.

When grasping that the sample SA has reached the softening point (Yes in step S2), the control unit resets the predetermined power (power at the time of ON) related to the large power information to 9.6 kW based on the power reduction information. (Step S3). Then, the output when the IH coil 2 is turned on becomes lower than before the softening point is reached, and induction heating suitable for maintaining the temperature near the softening point of the sample SA is performed.
Note that the switching to the low power related to the predetermined power is performed immediately after the sample SA reaches the softening point, instead of immediately after the cycle of the supply power at which the sample SA reaches the softening point. Is also good. When the specific power related to the small power information is not 0, the specific power may be reduced in accordance with the decrease in the predetermined power, or the specific power may be maintained without reducing the specific power. .

  When a predetermined time (for example, 220 seconds) elapses from the start of heating, the control means stops the intermittent operation of the IH coil 2 and completes the blister test by induction heating of the sample SA (step S4).

FIG. 3 is a graph showing the power (left vertical axis, W) and the total electric energy (right vertical axis, Wh (watt hours)) with respect to the elapsed time (horizontal axis, seconds) from the start of the test, and FIG. 5 is a graph showing various temperatures (left vertical axis, ° C.) with respect to elapsed time (horizontal axis, second). The various temperatures are the temperatures of the first to fourth portions of the sample SA, the coil cooling water inlet temperature, the coil cooling water outlet temperature, and the ambient temperature.
The following [Table 1] shows the elapsed time from the start of operation, the temperatures of the first to fourth portions of the sample SA, and the maximum temperature among them at the time of power switching and at the time of temperature saturation in the sample SA. And the minimum temperature (sample temperature difference).

The temperature of the sample SA at the start of heating (the average of the first to fourth portions, that is, the sample average temperature) is about 20 ° C., and the induction heating by the intermittently operated IH coil 2 makes the sample SA 2 minutes and 20 seconds later. The second part has reached the softening point (530 ° C.).
Induction heating is more efficient as the gap between the sample SA and the IH coil 2 is smaller, and the temperature of the fourth portion at the center of the sample SA is less likely to rise than other portions. In the blister test by the blister tester 1, the gap is set to be as large as 50 mm, so that the heating is gentler than in the case of a normal gap, and the edge of the sample SA close to the IH coil 2 and far from the IH coil 2. The temperature difference from the center of the sample SA is reduced.
Further, the intermittent operation prevents the sample SA surface close to the IH coil 2 from being rapidly heated, thereby preventing the sample SA from being altered unrelated to the generation of blisters. , And uniform heating of the sample SA is promoted. Even if the IH coil 2 is not an intermittent operation in which the IH coil 2 is turned on and off, but is a large / small switching operation by repetition of a large electric power (for example, 24 kW) and a small electric power (for example, 1 kW), the same effect as the intermittent operation is exhibited. Thereby, heating is performed faster than in the intermittent operation.
In FIG. 3, the magnitude of the large power (predetermined power) gradually increases as the time elapses. This is because the IH coil 2 and the like adapt to the elapse of the time.

When the softening point is reached, the predetermined power is switched from the initial value (24 kW) to the value (9.6 kW) related to the power reduction information (elapsed time: 2 minutes 22 seconds). The sample temperature difference at this time is 66.3 ° C.
By switching the predetermined power low, the temperature of the sample SA is maintained near the softening point, and the state in which the sample temperature difference is reduced is maintained.
The blister test can be completed in the vicinity where the saturation of the temperature in the sample SA is recognized, and the sample temperature difference at the time of saturation (elapsed time of 3 minutes and 40 seconds) is reduced to 43.6 ° C.

After the completion of the blister test, the sample SA was visually observed, and blisters were observed on the front and back surfaces of the sample SA.
Blisters are generated in a relatively short time (about 1 minute after reaching the softening point depending on the size and shape of the sample SA) when the sample SA is uniformly heated to the softening point. Therefore, by reaching the softening point (target temperature) after about 2.5 minutes and maintaining the temperature for about 1 minute, blisters can be generated in the entire sample SA by heating for about 3.5 minutes, and the blister test is completed. . Note that, unlike the above, when the sample SA is heated non-uniformly, a certain portion has a softening point or higher while another portion does not reach the softening point. It will not be done completely. When the sample SA is heated to a temperature higher than its melting point, at least a portion of the sample SA is melted and deformed, and the deformed portion and the blister cannot be distinguished or the blister-generated portion is melted. And the accuracy of the test is relatively low.

Such a blister testing machine 1 has the following operational effects.
That is, the blister tester 1 includes an IH coil 2 in which a sample SA is arranged, and control means for adjusting the output of the IH coil 2. After the output, the process of setting the specific output lower than the predetermined output is repeated.
Therefore, the heat source for heating the sample SA is the IH coil 2, and the operation and management of the blister tester 1 can be performed easily and safely. The blister tester 1 discharges only the coil cooling water and the electromagnetic waves having high intensity only at a short distance when the blister tester 1 is operated, and the influence on the environment is reduced. Furthermore, since the sample SA is heated so as to be as uniform as possible by repeating the predetermined output related to the IH coil 2 and the specific output lower than this, the inspection time can be as short as about 3.5 minutes. Can be performed accurately.

The specific output is 0, and the output of the IH coil 2 is turned on and off intermittently. Therefore, the sample temperature difference is further reduced.
Further, the control means lowers the predetermined output (output at 9.6 kW) after reaching the softening point of the sample SA before the temperature reaches the softening point (output at 24 kW). Thus, the temperature difference of the sample SA is reduced while the temperature of the sample SA is maintained near the softening point.
In addition, the distance (gap) between the sample SA and the IH coil 2 is 32 mm or more. Therefore, the sample temperature difference is further reduced.

On the other hand, in the blister test method that can be executed by the blister tester 1, the induction heating of the sample SA by the IH coil 2 sets the output of the IH coil 2 to a predetermined output, and then sets a specific output lower than the predetermined output. The sample SA is heated to a temperature equal to or higher than the softening point and lower than the melting point.
Thus, a blister test method is provided that is easier and safer to operate and manage, is more environmentally friendly, uniformly heats the sample SA, and has a relatively short inspection time.

The specific output is 0. Therefore, the sample temperature difference is further reduced.
Further, the predetermined output is reduced (output at 9.6 kW) after reaching the softening point of the sample SA before (at 24 kW) before reaching the softening point. Thus, the temperature difference of the sample SA is reduced while the temperature of the sample SA is maintained near the softening point.
In addition, the distance (gap) between the sample SA and the IH coil 2 is 32 mm or more. Therefore, the sample temperature difference is further reduced.

  1. Blister tester, 2. IH coil (coil), SA sample.

Claims (8)

A coil in which the sample is placed,
Control means for adjusting the output of the coil;
With
The blister tester according to claim 2, wherein the control means repeats, after setting the output of the coil to a predetermined output, to a specific output smaller than the predetermined output. The said specific output is 0, The blister test machine of Claim 1 characterized by the above-mentioned. 2. The control unit according to claim 1, wherein the predetermined output is lower after the temperature of the sample or the temperature around the sample than before reaching the softening point of the sample. Or the blister testing machine according to claim 2. The blister tester according to any one of claims 1 to 3, wherein a distance between the sample and the coil is 32 mm or more. For the sample, the induction heating by the coil is performed in a state where the output of the coil is set to a predetermined output, and then the specific output lower than the predetermined output is repeatedly performed, so that the sample has a softening point or more and a melting point or less. Blister test method characterized by being heated to a temperature. The blister test method according to claim 5, wherein the specific output is zero. 7. The method according to claim 5, wherein the predetermined output is decreased after the temperature of the sample or the temperature around the sample reaches the softening point of the sample, before the temperature reaches the softening point. The described blister test method. The blister test method according to claim 5, wherein a distance between the sample and the coil is 32 mm or more.

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