JP2023003612A - Method for manufacturing core for leak test - Google Patents

Abstract

To obtain a core capable of rapidly eliminating a deviation of a thermal distribution of high-pressure air in a leak test.SOLUTION: A method for manufacturing a core 10 for a leak test includes a molding process, a roughening process, and a film forming process. In the molding process, a fused resin material is put into an inspected object and solidified, so as to mold a core body 20 whose volume is smaller than the content volume of the inspection object. In the roughening process, surface roughness of the core body 20 is increased. In the film forming process, a front surface 25 of the core body 20 is coated by a coating sheet 30 which is made of a material with heat-conductivity higher than that of the core body 20.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method for manufacturing cores for leak testing.

Patent Literature 1 describes a method for manufacturing a core used for a leak test of a transmission case. In the core manufacturing method of Patent Document 1, a core is molded by pouring a molten resin material, a molten aluminum alloy, or the like into a transmission case and solidifying it.

Further, Patent Document 1 describes a method of leak test for a transmission case. In the leak test of Patent Document 1, a core is placed inside the transmission case. Next, with the opening of the transmission case closed, the gap between the inner surface of the transmission case and the core is filled with high-pressure air. Then, based on the pressure of the high-pressure air after a predetermined period of time has elapsed since the high-pressure air was filled, it is determined whether or not there is leakage of the high-pressure air in the transmission case.

JP-A-2000-046687

When high-pressure air is filled in the gap between the inner surface of the transmission case and the core in the leak test as disclosed in Patent Document 1, the heat distribution of the high-pressure air may become uneven in the gap. If the heat distribution of the high-pressure air is uneven in this way, the pressure of the high-pressure air changes due to the unevenness. Therefore, in the leak test as in Patent Document 1, it is necessary to wait until the heat distribution of the high-pressure air becomes uniform after the high-pressure air is filled. However, in the leak test of Patent Document 1, if a resin material having a relatively low thermal conductivity is used as the material of the core, it takes a long time until the heat distribution of the high-pressure air becomes uniform. On the other hand, if an aluminum alloy, which has a relatively high thermal conductivity, is used as the material for the core, the process for forming the core becomes complicated and the material cost increases.

A method of manufacturing a core for a leak test to solve the above-mentioned problems is to pour a molten resin material into the inside of an object to be inspected and solidify it to form a core body having a smaller volume than the internal volume of the object to be inspected. a roughening step of increasing the surface roughness of the core body; and after the roughening step, the surface of the core body is coated with a material having higher thermal conductivity than that of the core body. and a film forming step of applying a coating.

According to the above configuration, it is possible to obtain a core provided with a film having a higher thermal conductivity than the core body. Therefore, even if the heat distribution of the high-pressure air is uneven in the leak test, the heat is conducted through the film. Moreover, according to the above configuration, since the surface roughness of the core body is increased, the surface area of the coating applied to the surface of the core body is correspondingly increased. Therefore, heat exchange is efficiently performed between the high-pressure air and the film. That is, with the above configuration, it is possible to obtain a core capable of quickly eliminating uneven heat distribution of high-pressure air in a leak test. Further, since the core body itself is made of a resin material, complication of the molding process and an increase in cost can be minimized.

Front view of core. FIG. 4 is an end view showing an enlarged cross-sectional structure of part of the core; Explanatory drawing which shows the manufacturing method of a core. Explanatory drawing which shows the manufacturing method of a core. Explanatory drawing which shows the manufacturing method of a core. Explanatory drawing which shows the manufacturing method of a core. Explanatory drawing which shows the leak test using a core.

<Composition of the core>
An embodiment of the present invention will be described below with reference to FIGS. 1 to 7. FIG. First, the configuration of the core 10 for leak testing will be described.

As shown in FIGS. 1 and 2, the core 10 includes a core body 20 and a coating 30. As shown in FIGS. The shape of the core main body 20 is a shape corresponding to the internal space of an inspection object 50, which will be described later. In addition, in FIG. 1, the shape of the core main body 20 is simplified and illustrated as a quadrangular prism. As shown in FIG. 2 , the core body 20 has a surface 25 that includes six flat surfaces 21 and multiple recesses 22 . The recess 22 is recessed in the plane 21 of the core body 20 . The recesses 22 are located on five planes 21 of the six planes 21 of the core body 20 excluding the lower plane 21 . In addition, the lower plane 21 is a surface exposed in the third step described later. An example of the depth of the recess 22 is approximately 0.1 mm to 0.2 mm. In other words, the surface roughness of the core body 20 is about 0.1 mm to 0.2 mm when represented by the maximum height roughness, which is one of the indices of surface roughness. The material of the core body 20 is a resin material, and an example of the resin material is ABS resin. Although FIG. 2 shows the recesses 22 of the core body 20 in a uniform shape, the core body 20 has various recesses 22 with different sizes and shapes.

The coating 30 covers the entire surface 25 of the core body 20 . At the plane 21 where the recess 22 is located, the coating 30 is curved corresponding to the shape of the plane 21 and the recess 22 . In addition, in the plane 21 on which the recessed portion 22 is located, the surface roughness of the coating 30 is slightly larger than the surface roughness of the core body 20 when expressed by the maximum height roughness, which is one of the indices of surface roughness. It's getting smaller. The material of the coating 30 is a metal material, and an example of the metal material is an aluminum alloy. That is, the thermal conductivity of the coating 30 is higher than that of the core body 20 .

<Manufacturing method of the core>
Next, a method for manufacturing the core 10 will be described. As shown in FIG. 3, in manufacturing the core 10, an inspection object 50 to be inspected by a leak test is used. An example of the inspected object 50 is a transmission case. The inspected object 50 has a space inside. In addition, the inspected object 50 has an opening 51 directed to the outside. In this embodiment, the shape of the object 50 to be inspected is simplified and explained assuming that it has a substantially rectangular box shape.

As shown in FIG. 3, in the first step, the operator places the inspection object 50 with the opening 51 facing upward. Then, the operator attaches the heat-resistant material 60 to the side surface 52 of the object 50 to be inspected among the inner surfaces of the object 50 to be inspected. At this time, the operator attaches the heat-resistant material 60 so that the interior space of the object 50 to be inspected 50 becomes wider from the bottom surface 53 of the object 50 to the opening 51 . In other words, the operator forms an inclination, a so-called draft, with the heat-resistant material 60 for taking out the later-described core body 20A from the inside of the object 50 to be inspected. Also, the operator fills the recess 54 on the inner surface of the object 50 to be inspected with the heat-resistant material 60 . An example of the material of the heat-resistant material 60 is heat-resistant plastic.

As shown in FIG. 4 , in the second step after the first step, the operator pours the melted resin material into the inspected object 50 . At this time, the operator fills the entire internal space of the inspection object 50 with the molten resin material. Then, the worker waits for the resin material to harden inside the object 50 to be inspected, thereby molding the core main body 20A. At this stage, the core body 20A is slightly larger in volume than the core body 20 to be finally manufactured.

As shown in FIG. 5, in the third step after the second step, the operator takes out the core main body 20A from the inside of the object 50 to be inspected. Then, the worker exposes a new surface by scraping off a portion of the core body 20A including the one surface 20Aa, for example, by cutting. As a result, the core body 20B is molded from the core body 20A. At this time, an example of the amount of cutting from the one surface 20Aa of the core main body 20A is about 5 mm. The core body 20B at this stage has substantially the same volume as the core body 20 to be finally manufactured, but has a different surface roughness. One surface 20Aa of the core main body 20A is an end surface located on the opening 51 side when viewed from the bottom surface 53 of the object 50 to be inspected in the second step.

As described above, in the first step, the heat-resistant material 60 is arranged inside the inspection object 50 in addition to the resin material that is the material of the core main body 20A. Further, in the third step, the core body 20A is cut. Therefore, the volume of the core main body 20B is made smaller than the internal volume of the inspection object 50 by the first step and the third step. Further, in the present embodiment, the first to third steps are examples of the forming steps.

As shown in FIG. 6, in the fourth step after the third step, the worker forms the core body 20 from the core body 20B by forming the recess 22 in the surface of the core body 20B. Specifically, the worker arranges the core 10 so that the surface of the core main body 20B exposed in the third step is positioned downward. Then, the operator forms the recesses 22 by a process of colliding abrasive particles against the surface of the core body 20B, ie, a so-called blasting process. As a result, recesses 22 are formed in five of the six planes 21 of the core body 20 except for the lower plane 21 . In this embodiment, the third step is an example of a roughening step for increasing the surface roughness of the core body 20B.

As shown in FIG. 1 , in the fifth step after the fourth step, the worker applies the coating 30 to the surface 25 of the core body 20 . Specifically, the operator applies the coating 30 to the surface 25 of the core body 20 by evaporating the aluminum alloy, that is, by vapor deposition. That is, the fifth step is an example of a film-forming step of applying the film 30 made of a material having higher thermal conductivity than the core body 20 to the surface 25 of the core body 20 .

<Action of this embodiment>
First, the inspection device 100 used for the leak test will be described.
As shown in FIG. 7, the inspection apparatus 100 includes an apparatus body 110, a master container 120, a first communication path 130, and a second communication path 140. As shown in FIG. The apparatus main body 110 can be connected to the inspection object 50 via the first communication path 130 . The device main body 110 is connected to the master container 120 via the second communication path 140 . The master container 120 is a container that has an internal space and that ensures that there is no air leakage from the internal space. The apparatus main body 110 has a compressor (not shown). Therefore, when the object to be inspected 50 and the apparatus body 110 are connected via the first communication path 130 , the apparatus body 110 supplies high-pressure air to the internal space of the object to be inspected 50 via the first communication path 130 . supply is possible. Further, the device main body 110 can supply high-pressure air to the internal space of the master container 120 via the second communication path 140 . Further, the apparatus main body 110 has a differential pressure gauge (not shown). Therefore, when the object to be inspected 50 and the device main body 110 are connected via the first communication path 130 , the device main body 110 is connected to the pressure of the high-pressure air in the internal space of the object to be tested 50 and the pressure inside the master container 120 . A differential pressure can be measured with respect to the pressure of the high pressure air in the space.

Next, a leak test method will be described.
As shown in FIG. 7 , first, the worker places the core 10 on the workbench 200 . At this time, the worker arranges the core 10 such that the surface of the core body 20 exposed in the third step is positioned downward. In addition, the operator places the inspection object 50 on the work table 200 so as to cover the core 10 with the opening 51 of the inspection object 50 facing downward. As a result, the core 10 is positioned inside the object 50 to be inspected. Then, the operator connects the first communication path 130 of the inspection apparatus 100 to the object 50 to be inspected. At this time, the operator inserts the first communication path 130 into a through hole (not shown) of the object 50 to be inspected, so that a high pressure is applied from the device main body 110 to the internal space of the object 50 through the first communication path 130 . Allow air supply.

After the inspection device 100 is connected to the object 50 to be inspected, the operator operates the device body 110 so that the device body 110 supplies high-pressure air to the internal space of the object 50 to be inspected and the master container 120 . As a result, the gap Z between the inner surface of the object to be inspected 50 and the outer surface of the core 10 and the inner space of the master container 120 are filled with high-pressure air having a specified pressure. In addition, after a predetermined period of time has passed since the high-pressure air was filled, the apparatus main body 110 detects the pressure in the gap Z between the inner surface of the object to be inspected 50 and the outer surface of the core 10 and the pressure in the inner space of the master container 120. Measure the differential pressure between Then, the device main body 110 determines that there is leakage of high-pressure air from the test object 50 when the differential pressure is equal to or greater than a predetermined threshold. On the other hand, the apparatus main body 110 determines that there is no leakage of high-pressure air from the test object 50 when the differential pressure is less than the predetermined threshold value.

<Effects of this embodiment>
(1) According to the method for manufacturing the core 10 of the present embodiment, the core 10 provided with the film 30 having higher thermal conductivity than the core body 20 is obtained. Therefore, when the gap Z is filled with high-pressure air in the leak test, for example, the temperature of the high-pressure air in the first area ZA of the gap Z is higher than the temperature of the high-pressure air in the second area ZB of the gap Z. Heat is conducted through the coating 30 even if the coating 30 is elevated. Further, according to the method for manufacturing the core 10 of the present embodiment, the surface roughness of the core body 20 is increased, so that the surface roughness of the coating 30 applied to the surface 25 of the core body 20 correspondingly increases. will also grow. Therefore, the surface area of the coating 30 is increased. As a result, heat is efficiently exchanged between the high-pressure air in the first zone ZA and the portion of the coating 30 located in the vicinity of the first zone ZA. Similarly, heat exchange is efficiently performed between the high-pressure air in the second zone ZB and the portion of the coating 30 located near the second zone ZB. That is, in the present embodiment, it is possible to obtain the core 10 capable of quickly eliminating unevenness in the heat distribution of the high-pressure air in the leak test. Further, since the core body 20 itself is made of a resin material, complication of the molding process and an increase in cost can be minimized.

(2) In the leak test of the inspected object 50, the dimension between the bottom surface 53 of the inspected object 50 and the core 10 in the gap Z is determined according to the cutting amount in the third step. Therefore, in the present embodiment, compared to the case where the heat-resistant material 60 is attached to the bottom surface 53 of the object to be inspected 50 in the first step, the gap Z between the bottom surface 53 of the object to be inspected 50 and the core 10 is reduced. Easy to set dimensions with high accuracy.

(3) In the present embodiment, in the first step, the heat-resistant material 60 forms a draft for taking out the core body 20A from the inside of the object 50 to be inspected. As a result, in the third step, when removing the core body 20A from the inside of the object 50 to be inspected, it is possible to reduce the time taken in the work.

<Change example>
This embodiment can be implemented with the following modifications. This embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.

- In the above embodiment, the molding process may be changed.
For example, the first step may be omitted. As a specific example, depending on the shape of the object 50 to be inspected, the object 50 to be inspected may have a shape corresponding to a draft angle. In this case, even if the first step is omitted, the effect is small. If the first step is omitted, the second and third steps correspond to the molding step.

- For example, the third step may be omitted. As a specific example, the third step can be omitted by reducing the amount of the resin material to be poured into the inspected object 50 in the second step. As another specific example, the third step can be omitted by attaching the heat-resistant material 60 to the bottom surface 53 of the object to be inspected 50 in the first step. Incidentally, when the third step is omitted, the first step and the second step correspond to the molding step.

- In the said embodiment, you may change a roughening process.
For example, in the fourth step, instead of the blasting process, the recesses 22 may be formed by a process of corroding the surface of the core body 20B using an etchant, ie, a so-called etching process.

- For example, in the fourth step, the concave portion 22 may be formed by scraping off a portion of the surface of the core body 20B instead of blasting. In this case, it is preferable to form grid-like grooves on the surface of the core body 20B.

- For example, in the fourth step, the concave portion 22 may be formed by attaching a convex resin material to the surface of the core body 20B. When adopting this configuration, it is preferable to increase the thickness of the heat-resistant material 60 attached to the side surface 52 of the inspection object 50 among the inner surfaces of the inspection object 50 in the first step.

- For example, in the second step, the resin material is taken out from the inside of the inspected object 50 before the resin material is completely solidified inside the inspected object 50 . Then, the concave portions 22 may be formed by pressing a member having convex portions formed in advance, a metal ball, or the like against the resin material taken out. In this case, the fourth step can be omitted. That is, the roughening process does not have to be performed after the molding process, and may be performed in parallel with the molding process.

- For example, in the first step, the shape of the heat-resistant material 60 is adjusted to have a convex portion corresponding to the concave portion 22 . Then, in the subsequent second step, the concave portion 22 may be formed by solidifying the resin material inside the inspected object 50 . That is, the roughening process does not have to be performed after the molding process, and may be performed in parallel with the molding process.

- In the above embodiment, the range in which the roughening step is performed may be changed.
For example, in the fourth step, recesses 22 may be formed in six planes 21 of core body 20 . From the viewpoint of efficient heat exchange between the high-pressure air and the film 30 in the leak test, it is preferable to form the concave portion 22 at least in the plane 21 facing the inner surface of the test object 50 .

- In the above embodiment, the film forming process may be changed.
For example, in the fifth step, the coating 30 may not be applied by vapor deposition. As a specific example, the coating 30 may be applied by so-called plating, in which the coating 30 is applied to the surface 25 of the core body 20 in a liquid containing an aluminum alloy.

- In the above-described embodiment, the material of the core main body 20 is not limited to ABS resin as long as it is a resin material, and may be changed. For example, the core body 20 may be made of polypropylene, AS resin, or the like.

- In the above embodiment, the material of the coating 30 is not limited to the aluminum alloy, and may be changed. For example, the coating 30 may be made of chromium, nickel, gold, or the like. That is, as long as the thermal conductivity of the coating 30 is higher than that of the core body 20, the material of the coating 30 may be appropriately changed.

Z Gap ZA First area ZB Second area 10 Core 20 Core body 20A Core body 20Aa One surface 20B Core body 21 Flat surface 22 Concave portion 25 Surface 30 Coating 50 Coating Object to be inspected 51 Opening 52 Side surface 53 Bottom surface 54 Hollow 60 Heat-resistant material 100 Inspection device 110 Apparatus body 120 Master container 130 First communication path 140 Second communication path 200 Workbench

Claims (1)

a molding step of pouring a molten resin material into an object to be inspected and solidifying it to form a core body having a smaller volume than the inner volume of the object to be inspected;
a roughening step of increasing the surface roughness of the core body;
A method of manufacturing a core for a leak test, comprising: a film forming step of applying a film made of a material having a higher thermal conductivity than that of the core body to the surface of the core body after the roughening step.

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