JP3452660B2 - Method and apparatus for detecting defects of honeycomb formed body - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a honeycomb formed body, and more particularly to an inspection method and an apparatus suitable for easily detecting defects existing inside the formed body.

[0002]

2. Description of the Related Art Conventionally, a honeycomb shape has been adopted as a catalyst shape because it can have a large area per unit volume. The honeycomb catalyst is formed by extrusion-molding a raw material paste from a die, and is manufactured by being dried and fired. In the process of extrusion molding, residual molding stress may occur due to inhomogeneity of the paste, uneven temperature during molding, uneven processing accuracy in the die passage, and cracks may occur during drying or firing. Even a homogeneously molded product may have cracks due to uneven drying speed during drying and cracks due to stress due to uneven temperature during baking. Among these cracks, cracks that occur on the outer periphery can be sufficiently discriminated by visual observation, but it is extremely difficult to detect cracks in the flow direction of the flow path or at right angles that have occurred in the central portion. In an extreme case, if this honeycomb catalyst is transported or used with defects inside, it may be destroyed due to vibration or stress generated by an external force. Therefore, detecting defects inside the honeycomb molded body is an extremely important item in terms of product quality control.

[0003]

The following methods have been considered as methods for inspecting honeycomb formed bodies, but none of them are perfect methods, and there is room for improvement.
One method uses the principle that light is scattered if there are cracks in the honeycomb cell flow channel, and light is applied from the end face.
This is a light transmission method in which the intensity is detected on the opposite side and the presence or absence of cracks inside the cell channel is estimated by the degree of attenuation. According to this method, unevenness of cell surface roughness caused by a difference in flow resistance of the die flow path, a difference in reflectance due to a temperature difference during firing, and a slight difference in redox of the catalyst component are generated. It is difficult to distinguish the attenuation degree of the light scattering intensity due to the above case from the attenuation degree of the light scattering intensity due to the crack. Another method uses vibration, which is a tapping test method that uses the principle that the natural frequency of the honeycomb formed body varies depending on the presence or absence of cracks in the cell flow passage. Although this method can detect extremely large cracks, it is difficult to detect small cracks.

Another method is a method of direct X-ray imaging. In this case, it is difficult to detect cracks in the cell flow passage direction of the honeycomb formed body, and it is also difficult to detect cracks in the direction perpendicular to the cell flow passage in the case of the long honeycomb formed body. In addition to this, when a heat flux is applied from one direction of the honeycomb formed body, a thermal method using the principle that a portion where a crack exists in the cell becomes a heat resistance body and a sudden temperature drop occurs To be In this case, it is difficult to detect cracks in the cell flow path direction of the honeycomb formed body and cracks in the direction perpendicular to the long flow path, and it may not be possible to inspect with a material having a small thermal conductivity. An object of the present invention is to provide a method and a device for surely detecting the presence or absence of cracks inside the cell channels of a honeycomb formed body by a simple method.

[0005]

The object of the present invention is achieved by the following constitutions. That is, it has open ends at both ends
A honeycomb molded body formed by arranging a plurality of cells having a honeycomb section in parallel is plugged at all the open ends of one end surface of the molded honeycomb body , and
Among the cell open end group on the opposite end face of the honeycomb molded body, cell internalization by examining allowed to flow into one or the gas in the cell from the plurality of cells open end, the presence or absence of leakage of the gas discharged from the other the cell This is a method for detecting defects in a honeycomb formed body for detecting defects. Here, the cell intrinsic defects of the honeycomb molded body, and the gas pressure or gas flow rate in one or a plurality of any cell Ru allowed to flow into the gas, from the cells other than the cell
The presence or absence of leakage can be checked by comparing the pressure of discharged gas or the flow rate of gas.

Further, the object of the present invention is achieved by the following constitution. That is, multiple cross-sections with open ends at both ends
One or more of an end face sealing member for plugging all the cell open ends of one end face of a honeycomb formed body in which honeycomb cells are arranged in parallel, and a cell open end group on the opposite end face of the honeycomb formed body a gas supply member for flowing gas into individual cells open ends, flowing a gas before Symbol opposite end face
A defect detecting device for a honeycomb formed body, comprising a chamber for detecting a leaked gas that covers the cell open end other than the cell open end , and a gas pressure gauge or a gas flow meter provided in the gas supply member and the leak gas detection chamber. .

[0007]

The individual cells of the honeycomb formed body are divided by the cell walls to form independent flow paths. In such a healthy honeycomb molded body, when pressurized gas is introduced from one side of one or a plurality of cell flow paths , the pressure inside the cell rises.
However, the pressurized gas does not flow out of the cells other than the cell into which the pressurized gas flows. However, if a crack exists in the central portion or the like in the cell flow channel in a direction perpendicular to or parallel to the flow channel direction, the gas flow channel is connected through the crack. Thus, the present invention detects fluid leakage resulting from flow path short circuit due to cracks by measuring changes in gas pressure or flow rate. Specifically, a cell defect is detected by injecting a pressurized gas into one or more cells of the cell group on the end face of the honeycomb formed body and examining the degree of leakage from other cells. A value measured by a pressure gauge or a flow meter may be used as an indicator of the degree of leakage.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. An example of the inspection apparatus shown in FIG. 1 will be described. First, one end surface of the honeycomb formed body 1 placed on the inspection table 9 is completely plugged by the end face seal plate 2. A pressurized gas supply probe 3, which is movable in three dimensions (XYZ axes) for supplying pressurized gas from the other end face, and a cell other than the pressurized gas supply probe 3 are bundled into one flow path. And a leak gas collecting chamber 4 with a pressure gauge. The chamber 4 must have a flexible structure so that the probe 3 can be fixed at an arbitrary position on one end surface of the honeycomb molded body 1. The point for mounting the inspection apparatus of this embodiment on the honeycomb molded body 1 of the object to be inspected is to prevent the pressurized gas from leaking without damaging the end surface of the product. For this reason, a soft urethane sealing material is preferably used for the portion where the end face seal plate 2, the pressurized gas supply probe 3, and the leaked gas collecting chamber 4 are in close contact with the honeycomb molded body 1.
Further, the pressurized gas is supplied from the pressurized gas supply header 6 to the pressurized gas supply probe 3 with the probe traverse device 5. The pressure of the pressurized gas is detected by the supply gas pressure detector 7 provided in the pressurized gas supply header 6, and the pressure of the leak gas from the cell is detected by the leak detection pressure gauge 8 provided in the leak gas collecting chamber 4. To be done.

Next, an inspection method using the inspection mounting will be described. A gas pressurized to a pressure P ₀ is supplied to a certain portion by the pressurized gas supply probe 3, and the leak detection pressure P ₁ in the leak gas collecting chamber 4 in the other flow paths is checked.
The pressure of the P ₀ and P ₁ is measured, P ₁ relative to the reference pressure P ₀
If a certain threshold value is exceeded, at least the flow path in the cell in which the probe 3 is set and the flow path in the other cells are connected by a crack. Similarly, while traversing the position of the probe 3 in the plane (X, Y axis) direction of the end face of the honeycomb molded body 1, by repeating this operation, the presence or absence of cracks in the cells having the opening in the entire region of the end face is determined. The position of the crack can be estimated.

Specific device size specifications may be determined according to the following idea. The size of the pressurized gas supply probe 3 needs to be set according to the allowable size of the crack of the product. That is, if the allowable size of the crack is small, the probe 3
It is necessary to make the tip of the small. In addition, the width of the surface of the tip of the probe 3 that is in close contact with the end surface of the honeycomb molded body 1 must be longer than the diagonal line of one cell. That is, when the supply unit of the pressurized air and the leak gas collecting chamber 4 are shared in one cell, the chamber 4 is not affected by the presence or absence of cracks.
This is because the pressure at the point rises, and the crack cannot be detected accurately. The pressure of the supplied pressurized gas may be set according to the material of the honeycomb formed body 1 and the allowable opening width of cracks.

In the embodiment shown in FIG. 1, the test honeycomb molded body 1 has an outer shape of 150 mm square, a length of 500 mm, a cell pitch of 3.5 mm, a rib thickness of 0.5 mm, and an opening size of 3 mm.
The target was the TiO ₂ -based denitration catalyst of Kaku. The dimension of the joint surface of the pressurized gas supply probe 3 with the honeycomb formed body 1 is 30.
The leak gas collecting chamber 4 is made of rubber having a size of 1 mm and a width of 5 mm, and the leak gas collecting chamber 4 is made of rubber. The probe 3 is located substantially in the center of the chamber 4.
The connection between the chamber 4 and the honeycomb formed body 1 is sealed by the bands 10 and 11. The opposite end face of the honeycomb formed body 1 was plugged with an end face seal plate 2 made of a urethane material having airtightness.

FIG. 2 shows the case where the honeycomb formed body 1 of this embodiment is sound, and FIG. 3 shows the flow of the pressurized gas when there is a crack in the direction perpendicular to the cell flow path of the honeycomb formed body 1. FIG. 4 is a schematic diagram showing the flow of the pressurized gas when there is a crack in the direction parallel to the cell channels of the honeycomb formed body 1. The pressure of the supply air was set to 100 mmAq, and the test body of the honeycomb formed body 1 was inspected by the apparatus shown in FIG. As a result, the leak detection pressure gauge 8 hardly raises the pressure 0 to 2
Regarding 0 mmAq, when the inside of the specimen was cut and examined, it was sound without cracks. In the leak detection pressure gauge 8 that increased by 100 mmAq or more at the maximum, there were several cracks with a wide opening width (1 mm or more) of about φ80 mm in the direction perpendicular to the flow path direction. Also, the maximum is 10 to 100 mmA.
In the test body in the range of q, cracks (hair cracks) having a narrow opening width of about 100 mm and a width of about 100 mm in the longitudinal direction on the surface passing through the honeycomb axis, and a narrow opening width in the direction perpendicular to the flow channel direction. A crack was detected.

With this device, the supply pressure is 100 mmAq,
With the threshold value of the leak detection pressure gauge 8 set to 20 mmAq, the presence or absence of internal cracks could be determined. The devices 7 and 8 for measuring the supply flow rate of the pressurized gas and the flow rate from the leaking gas collecting chamber 4 of the apparatus of the above-mentioned embodiment were respectively attached, and the presence or absence of cracks was inspected by the flow rate measurement values of both. It was found that it is possible to inspect for cracks as in the case of measuring the pressure value of the pressurized gas.

[0014]

By using the defect detector for a honeycomb molded body of the present invention, it is possible to easily find a crack existing inside the honeycomb molded body in parallel to the flow channel direction or in a vertical direction. In particular, it exerts a great effect on the quality control of a honeycomb molded body of a long product. By inspecting the honeycomb formed body, it is possible to prevent damage in advance during transportation or use in an actual machine.

[Brief description of drawings]

FIG. 1 is a view showing a defect detector of a honeycomb formed body according to an embodiment of the present invention.

[Fig. 2] Fig. 2 is a schematic view showing a case where the honeycomb formed body according to the present invention is sound.

[Fig. 3] Fig. 3 is a schematic diagram showing a flow of a pressurized gas when there is a crack in a direction perpendicular to a cell channel of a honeycomb formed body according to the present invention.

[Fig. 4] Fig. 4 is a schematic diagram showing a flow of a pressurized gas when there is a crack in a direction parallel to a cell channel of a honeycomb formed body according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Honeycomb molded body, 2 ... End face seal plate, 3 ... Pressurized gas supply probe, 4 ... Leakage gas collecting chamber with a pressure gauge,
5 ... Probe traverse device, 6 ... Pressurized gas supply header, 7 ... Supply gas pressure detector, 8 ... Leakage detection pressure gauge, 9
… Inspection table, 10, 11… Band

─────────────────────────────────────────────────── --Continued from the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01M 3/26 G01M 3/32 B01D 53/86 ZAB

Claims (3)

(57) [Claims] 1. A plurality of cross-section hanika having open ends at both ends.
All the open ends of the cells on one end surface of the honeycomb molded body in which the honeycomb-shaped cells are arranged in parallel are plugged to remove the honeycomb molded body from the opposite side.
Gas is allowed to flow into the cell from one or more cell open ends of the cell open end group on the opposite end face,
A method for detecting defects in a honeycomb formed body, which comprises detecting defects existing in cells by checking for the presence of leakage of discharged gas. Cell intrinsic defects wherein the honeycomb molded body, and the gas pressure or gas flow rate in one or a plurality of any cell Ru flowed gas, <br/> gas discharged from cells other than the cell defect detection method features and to Ruha honeycomb molded body that comparison of pressure or gas flow conducted by examining the presence or absence of leakage. 3. A plurality of cross-section hanika having open ends at both ends.
An end face sealing member for plugging all the cell open ends of one end face of a honeycomb formed body in which honeycomb-shaped cells are arranged in parallel ,
Among the cell open end group on the opposite end face of the honeycomb molded body, a gas supply member for flowing gas in one or a plurality of cells open end, cell opening for flowing gas before Symbol opposite end face
Defect detection of a honeycomb formed body characterized by comprising a chamber for leaking gas detection covering the cell open end other than the end , and a gas pressure gauge or gas flow meter provided in the gas supply member and the leaking gas detection chamber apparatus.