JPH06103240B2 - Liquid tank leak inspection method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a leak inspection method for a liquid tank.

[Prior Art] As is well known, in a liquid tank such as a domestic bathtub, a wash bowl, a sink or a water storage tank, the liquid tank main body is generally made of a material such as synthetic resin, enameled or stainless steel. Since it is molded, there is almost no risk of liquid leakage from the partition wall itself.

However, the drainage port, the hot water supply port, etc. usually have a structure in which a hole is provided in the liquid tank body and a predetermined metal fitting is fastened and fixed to the hole via a seal member (packing). Liquid leakage may occur around the metal fittings due to poor finishing, biting of dust, defective packing, or insufficient tightening force. Particularly, in the case of a domestic bathtub, the above-mentioned liquid leakage may be directly connected to the leakage to the ceiling portion below the floor. For this reason, normally, after the metal fittings have been assembled to the bathtub body, a leak inspection is performed on all assembled products.

Conventionally, the leak inspection generally stores water in a bathtub up to a predetermined depth (for example, about 80% of the total depth) and leaves it for a long time (for example, one day and night) to leak water around the metal fittings. It is carried out by a so-called water filling test, which visually checks for the presence or absence.

However, the above-mentioned conventional inspection method has the following problems.

The inspection takes a long time.

After the product is assembled, it cannot be inspected online on the production line, resulting in low production efficiency.In addition, if a defective product is found, repair / re-inspection cannot be performed immediately on the spot. , Has to bring it back to the line again, causing a big mess on the production line.

Requires a large inspection space. That is, since products cannot be stacked during the inspection, it takes a long time for the inspection, and it becomes difficult to secure the inspection space especially when the production quantity increases.

A large amount of water is required, and a great deal of labor is required to fill water, drain water, and remove water adhering to the product.

In some cases it may be difficult to determine whether the result is acceptable or not. That is, after water filling,
It is necessary to completely remove the water adhering to the metal fittings and to protect other water from splashing during the inspection. In a dry atmosphere, it is difficult to detect a small amount of leaks.
The bottom side of the bottom of the tank is difficult to see.

Therefore, the applicant of the present application, after covering the metal fittings from the back side of the liquid tank main body with the inspection tool, makes the space formed by the inspection tool and the back surface of the liquid tank main body a predetermined negative pressure, On the same day, we applied for a leak inspection method for a liquid tank that inspects leakage around metal fittings by measuring the decrease in negative pressure after the passage of time.

According to this inspection method, it is possible to solve the above-mentioned conventional problems, perform a leak inspection of a liquid tank online on a production line in a short time with a relatively simple operation, and easily determine pass / fail. It can be performed.

[Problems to be Solved by the Invention] However, in the above inspection method using negative pressure,
Since it is necessary to bring the inspection tool into contact with the back side of the liquid tank to keep the above-mentioned space airtight, it cannot be applied unless the surface state on the back side of the liquid tank is sufficiently smooth.

That is, for example, in the case of a liquid tank made of plastic, for example, in the case of the sheet molding compound method (SMC method), etc., the tank body is molded in a precise molding die and the final coating is formed in this mold. For things, it is possible to obtain a sufficiently smooth surface condition not only on the inner surface of the liquid tank but also on the back surface side, but for example, by hand lay-up or spray-up,
It is unavoidable that the surface condition on the back side is at least somewhat rough, and it becomes difficult to seal the back surface of the liquid tank body and the inspection tool air-tight even if a seal member is interposed, and negative pressure is applied. However, there is a drawback that the above-mentioned inspection method using the above method cannot be applied.

The present invention has been made in view of the above problems, and can be inspected by using negative pressure regardless of the surface condition of the back surface side of the liquid tank body, and solves the above-mentioned problems. It is an object of the present invention to provide a leak inspection method for a liquid tank that can be used.

[Means for Solving the Problems] Therefore, according to the present invention, a tube body having one end protruding to the outside of the liquid tank main body is fixed to a hole provided in the liquid tank main body, and
In the inspection method for inspecting leakage around the pipe body of the liquid tank in which the back side of the liquid tank main body has a relatively rough surface state,
After the first inspection tool is attached to one end of the tubular body protruding outside the liquid tank main body via the seal member, the other end of the tubular body is closed with a sealing plug material, A negative pressure of a predetermined value is applied to the first space portion formed by the plug member, the tube body, and the first inspection tool, and then, this negative pressure is sealed, and then a predetermined time elapses. A first test for measuring the subsequent decrease in negative pressure and determining acceptance / rejection based on this measurement value, and a cup-shaped second test having a seal member at the peripheral edge with the other end of the tubular body open. After the pipe is covered with the inspection tool from the inner surface side of the liquid tank main body, the second space formed by the first and second inspection tools, the liquid tank main body, and the pipe is covered by the negative pressure generating means. A second test is performed in which the negative pressure is set to a predetermined value, the negative pressure is sealed next, and then the decrease in the negative pressure after a predetermined time has elapsed is measured, and the pass / fail is determined based on the measured value. It is obtained to carry out the door.

[Effects of the Invention] According to the present invention, after the first inspection tool is attached to one end of the tubular body projecting to the outside of the liquid tank main body, a negative pressure is sealed in the first space and time is maintained. A first test for measuring the decrease in negative pressure with the passage of time to make a pass / fail determination, and a negative inspection by sealing the negative pressure in the second space portion and measuring the decrease in the negative pressure over time. Since the second inspection is performed,
While the first inspection can inspect the leakage at the closed portion of the pipe body due to the plug material, the second inspection can inspect the leakage at the fixed portion of the pipe body to the liquid tank body. That is, it is possible to separately inspect the leakage at these two locations, and it is possible to easily identify and repair the leakage location when the leakage occurs. Moreover, in this case, in the second inspection, the pipe body is covered with the second inspection tool from the inner surface side of the liquid tank body, and the first and second inspection tools, the liquid tank body and the pipe body are formed. Since the leakage inspection around the pipe body is performed by setting the negative pressure in the formed second space portion, it is not necessary to use the back surface side of the liquid tank main body as the sealing surface. Therefore, regardless of the surface condition of the back surface side of the liquid tank body, the leak inspection method using negative pressure can be applied, and the above-mentioned various problems can be effectively solved.

That is, compared to the conventional water filling test, the time required for pass / fail judgment can be shortened, and water filling, drainage, and removal of adhering water after inspection are unnecessary, and inspection can be performed with a simple operation. You can As a result, online inspection can be performed on the production line, productivity can be greatly improved compared to the past, and repair / re-inspection of rejected products can be performed smoothly. it can. Furthermore, there is no need to separately secure a large inspection space. Further, since the pass / fail determination can be performed by reading the decrease in negative pressure numerically, the pass / fail determination can be performed more easily and accurately than in the conventional case in which the presence or absence of water leakage is visually determined.

[Embodiment] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings, in the case of being applied to a leak inspection of a domestic bathtub.

FIG. 1 is an overall configuration diagram showing a schematic configuration of a domestic bathtub and a leakage inspection apparatus for this bathtub according to the present embodiment. As shown in FIG. 1, the bathtub 1 is, for example, a fiber-reinforced synthetic resin. It is formed by hand lay-up using the material as a raw material, and a substantially tubular drainage fitting 2 having one end protruding toward the back side of the bath 1 is attached to the hole 1a provided in the bottom surface thereof, The metal fitting 2 is provided with a drainage port 2a penetrating in the longitudinal axis direction. Further, one end of a chain member 4 is fixed to the side wall portion of the bathtub 1, and a rubber plug member 3 (rubber plug) for closing the drainage port 2a is attached to the other end of the chain member 4. .

As shown in detail in FIG. 2 and FIG. 3, the drainage fitting 2 has a seal member 7 (first packing) interposed between the lower surface of the upper end flange portion 2b and the inner surface of the bath body 1. The lock nut 5 is fixed to the bathtub body 1 by tightening the lock nut 5 on the threaded portion screwed on the outer peripheral portion of the metal fitting.
A seal member 8 (second packing) is interposed between the upper surface of the lock nut 5 and the back surface of the bath body 1. Although the back surface side of the bath body 1 is rougher than the inner surface side, the sealing surface for the second packing 8 is finished to be smooth. Further, the lower end surface of the drainage fitting 2 is finished to be sufficiently smooth, and more preferably, the lower end side of the fitting 2 is the lock nut 5.
The total length of the drainage fitting 2 is set so as to project downward from the lower end surface by a predetermined length.

An adapter 15 for closing the lower end side of the drainage port 2a is fastened and fixed to the lower end portion of the drainage port metal fitting 2 at the time of performing a leak inspection around the drainage port metal fitting 2, and the adapter 15 and the drainage port fitting 2 are connected. A seal member 16 is provided between the lower end surface and the lower end surface to hermetically seal the two. Further, one end of a tube 19 is connected to the adapter 15, and the other end of the tube 19 is connected to the leak inspection device 20 side.

On the other hand, on the inner surface side of the bottom of the bathtub 1, the drainage fitting 2
When performing a leak inspection of the periphery of the bath, the cup-shaped cover member 11 for covering the drainage fitting 2 and the periphery thereof from the inner surface side of the bathtub 11
A seal rubber 12 for airtightly sealing between the cover member 11 and the inner surface of the bath body 1 is adhesively fixed to the lower surface side of the peripheral flange portion 11a of the cover member 11. In addition, on the inner surface side of the bath body 1, at least the periphery of the mounting portion of the drainage fitting 2 is finished to have a smooth surface.

The leak inspection device 20 (see FIG. 1) is a pressure reducing valve 21 for reducing and adjusting compressed air in a factory, and a negative pressure generating device for generating negative pressure by passing compressed air from the pressure reducing valve 21. 22 (a so-called convum) and a negative pressure gauge 23 for measuring a negative pressure in a negative pressure pipe 26 provided on the downstream side of the negative pressure generating device 22, and the end of the negative pressure pipe 26 has the tube 19 It is connected to the. Further, an opening / closing valve 25 (first opening / closing valve) is provided in the air pipe 24 connecting the pressure reducing valve 21 and the negative pressure generating device 22.
On the other hand, a second opening / closing valve 27 is arranged upstream of the negative pressure measuring unit 28 of the negative pressure pipe 26.

The negative pressure generator 22 is not specifically shown,
It has a venturi tube inside and takes out negative pressure generated when compressed air passes through a slot part (not shown) of this venturi tube at a high speed. It can easily generate negative pressure using normal factory air. You can Instead of using the compressed air and the negative pressure generating device 22, the negative pressure may be generated by other negative pressure generating means such as a normal vacuum pump.

An inspection method for inspecting leakage around the drainage fitting 2 of the bathtub 1 using the leakage inspection device 20 configured as described above will be described with reference to the flowchart of FIG.

First, the drainage fitting 2 is attached to the hole 1a of the bathtub 1 and fastened and fixed by the lock nut 5 (step # 1), and then the adapter 15 is fastened and fixed to the lower end of the drainage fitting 2 (step # 2). ). Then, in step # 3, compressed air in the factory (for example, pressure of about 5 kg / cm ² ) is supplied to the pressure reducing valve 21 of the leakage inspection device 20.

After completing the above preparation steps, a leak inspection is performed online on the product assembly line. In the present embodiment, the leakage inspection is an inspection step (first inspection step) for inspecting leakage from the seal portion between the inner surface of the drainage port 2a and the rubber plug 3, and the first packing 7 and the second packing 8 respectively. The inspection process (second inspection process) for inspecting leakage from the upper and lower seal portions is performed separately.

That is, first, the drainage port 2a is closed with the rubber plug 3 (step # 4), then, in step # 5, the first on-off valve 25 is opened to generate a negative pressure in the negative pressure generating device 22, and then, Step # 6
The second on-off valve 27 is opened with. By this valve operation, the first part formed by the drainage fitting 2, the rubber plug 3, and the adapter 15
Negative pressure is introduced into the space 17. Next, step # 7
By adjusting the pressure reducing valve 21, the negative pressure gauge 23 adjusts the negative pressure so that the negative pressure gauge 23 shows a preset predetermined value (for example, 400 mmHg). By keeping the space 17 at a negative pressure, the seal between the inner surface of the drainage port 2a and the rubber plug 3 is subjected to a pressure in the same direction as in actual use.

The negative pressure gauge 23 is graduated so that the higher the negative pressure (vacuum degree), the higher the numerical value. For example, when the negative pressure is 400 mmHg, the pressure difference from the atmospheric pressure (that is, the seal portion). If the pressure acting on the head is converted to a water head, it corresponds to about 5.3 m. This corresponds to about 10 times the water pressure value in the conventional water filling test (that is, in actual use), so it is an accelerated test and can shorten the inspection time.

After the setting in step # 7 above, step #
At 8, the second on-off valve 27 is closed to seal the negative pressure in the space 17 and the elapsed time after the start of this sealing is measured (step # 9). Then, after a lapse of a predetermined time (for example, 30 seconds), in step # 10, the negative pressure gauge 23 is read to measure the decrease in negative pressure, and in step # 11, a pass / fail judgment is made based on the measured value. In this example, if the negative pressure value after the above-mentioned predetermined time passed was 350 mmHg or more, it passed, and if it was less than this value, it was rejected.

After completing the above first inspection process, the rubber plug 3 is removed from the drain port 2a to release the negative pressure in the space 17 (step #
12). If the result of the first inspection is unacceptable, the drainage fitting 2 is immediately removed to check the fitting 2 and the rubber plug 3 on the spot, and cleaning and repair such as parts replacement are performed. After carrying out, the drainage fitting 2 is assembled again and a re-inspection is carried out. Also, the first
If the inspection result is acceptable, the second inspection process is subsequently executed.

That is, in step # 13, the cover member 11 is brought into contact with the inner surface side of the bottom surface of the bathtub 1 via the seal rubber 12, and then in step # 14, the second opening / closing valve 27 is opened. By this valve operation, the space portion 18 (second space portion) defined by the cover member 11, the bath body 1, the drainage fitting 2 and the adapter 15 is formed.
Negative pressure is introduced inside.

By maintaining the second space portion 18 at a negative pressure, the cover member
11 is pressed and fixed to the inner surface side of the bathtub 1 by the pressure difference between the outside and the inside of the second space portion 18. Therefore, the cover member 11 can be fixed to the bathtub side without using a special fixing jig or the like. Further, in this case, a pressure in a direction relatively opposite to that in actual use acts on the upper and lower seal portions of the first packing 7 and the second packing 8, respectively.
In this regard, as will be described later in detail, it was confirmed by a comparative verification test with a conventional water filling test that the inspection result by the method of the present invention has sufficient reliability.

After the step # 14 is completed, the steps # 7 to # 10 in the first inspection process are sequentially executed in steps # 15 to # 18. Then, in step # 19, a pass / fail judgment is made based on the same judgment criteria as in the case of the first inspection step. In addition, regarding those judged to be unsuccessful in this pass / fail judgment, immediately on the spot, the drainage fitting 2
Is removed and checked, and after cleaning and replacement such as replacement of parts, the drainage fitting 2 is assembled again and re-inspection is performed.

When determining the acceptance criteria in the first inspection step and the second inspection step, a comparative verification test was performed to compare the inspection result of the conventional water filling test with the inspection result of the method of the present invention.

In the above water filling test, water is poured into the bathtub to a water level of about 50 cm, left standing for 24 hours, and then visually checked for water leaks. The test results are shown in Table 1, and in the inspection in the first inspection step of the method of the present invention,
No leak was found in the water filling test for those having a negative pressure value of 375 mmHg or more after 30 seconds from the negative pressure sealing (Samples 1 and 2). The second of the method of the present invention
In the inspection in the inspection process, there was no leakage in the water filling test for the negative pressure value of 360 mmHg or more (Samples 3 and 4), and a slight water leak for the negative pressure value of 250 mmHg (Sample 5). was detected.

Therefore, those showing a negative pressure value of 350 mmHg or more are acceptable,
For those less than this, by rejecting,
It is possible to perform a highly reliable leak test corresponding to the water filling test performed under the condition closest to the actual use condition.

As described above, according to the method of the present invention, the adapter is provided at the end portion of the drainage fitting 2 protruding outside the liquid tank body 1.
15 is attached, the drain port fitting 2 is covered with a cover member 11 from the inner surface side of the liquid tank body 1, and the adapter 15
Since the space 18 formed by the cover member, the liquid tank body 1 and the drainage metal fitting 2 is made to have a negative pressure, the leakage inspection around the drainage metal fitting 2 is performed. It is not necessary to use the back side as the sealing surface. Therefore,
Regardless of the surface condition of the back side of the liquid tank body 1, it is possible to apply the leak inspection method using negative pressure,
It is possible to effectively solve the above problems.

In the above embodiment, after the leakage inspection (first inspection step) from the seal portion between the inner surface of the drainage port 2a and the rubber plug 3 is completed, the sealing of the first and second packings 7 and 8 is continued. Although the leakage inspection from the section (the second inspection step) is performed, the order may be reversed.

Further, in the above embodiment, the negative pressure value of the space portions 17 and 18, the holding time after the negative pressure sealing, and the determination standard are set to be the same in the first inspection process and the second inspection process. However, these may be separately determined according to the characteristics of the seal portion inspected in each inspection process.

In addition, although the above-mentioned example was about the leak inspection around the drainage fittings of the domestic bathtub, the method of the present invention is not limited to the above case, and can be applied to the leak inspection around other fittings such as the hot water inlet fittings. Can also be applied, for example, a washbasin,
The present invention can also be applied to other general liquid tanks such as sinks or water storage tanks, and leakage inspection around metal fittings such as tanks for storing powders and the like.

[Brief description of drawings]

The drawings are all for explaining the embodiments of the present invention. FIG. 1 is an overall configuration diagram showing an outline of a bathtub and a leak inspection device, and FIG. 2 is a drainage port metal fitting and an adapter mounting portion in the first inspection process. FIG. 3 is an enlarged vertical sectional view of the drainage port metal fitting, the adapter and the cover member mounting portion in the second inspection step, and FIG. 4 is a flowchart of the inspection step. DESCRIPTION OF SYMBOLS 1 ... Bathtub, 1a ... Hole part, 2 ... Drainage port metal fittings (tubular body), 11 ... Cover member (2nd inspection tool), 11a ... Peripheral flange part, 12
… Rubber seal, 15… Adapter (first inspection tool), 16…
Seal member, 18 ... Space part, 20 ... Leakage inspection device, 22 ... Negative pressure generating device, 23 ... Negative pressure gauge.

Claims (1)

[Claims] 1. A liquid tank in which a pipe having one end protruding outside the liquid tank main body is fixed to a hole provided in the liquid tank main body, and a rear surface side of the liquid tank main body has a relatively rough surface condition. Regarding the inspection method for inspecting leakage around the pipe body, the pipe body is installed after the first inspection tool is attached to one end portion of the pipe body protruding outside the liquid tank main body through a seal member. In a state where the other end of the plug is closed with a plug having a sealing property, the first space formed by the plug, the tube, and the first inspection tool has a predetermined value of negative pressure generated by negative pressure generating means. Pressure, then, after sealing this negative pressure, measure the decrease in negative pressure after a lapse of a predetermined time, open the other end of the tubular body and the first inspection to judge pass / fail by this measured value. In this state, after covering the pipe body from the inner surface side of the liquid tank main body with the cup-shaped second inspection tool having the seal member on the peripheral portion, The second space portion formed by the first and second inspection tools, the liquid tank main body, and the pipe body is made to have a negative pressure of a predetermined value by the negative pressure generating means, and then this negative pressure is sealed, and then the predetermined pressure is set. A method for inspecting leakage of a liquid tank, comprising: measuring a decrease in negative pressure after a lapse of time, and performing a second inspection to judge pass / fail based on the measured value.