CN107024323B

CN107024323B - Leak inspection device and leak inspection method

Info

Publication number: CN107024323B
Application number: CN201611050911.0A
Authority: CN
Inventors: 高根将希; 佐佐木行雄
Original assignee: Yamaha Fine Technologies Co Ltd
Current assignee: Yamaha Fine Technologies Co Ltd
Priority date: 2015-11-26
Filing date: 2016-11-24
Publication date: 2020-09-22
Anticipated expiration: 2036-11-24
Also published as: CN107024323A; JP6637298B2; KR101961229B1; KR20170061597A; JP2017096833A

Abstract

Provided are a leak inspection device and a leak inspection method, which can detect a leak with high accuracy and can repeatedly use a sealing member. The leakage inspection device is provided with: an inspection chamber capable of receiving a workpiece; a pressing member that seals an opening of the workpiece in the inspection chamber by pressing the sealing member into contact with the opening, and separates the inspection chamber into a sealed space portion on an inner side and an outer side of the workpiece; a gas supply means for supplying a trace gas to the sealed space portion on one of the inner side and the outer side of the workpiece; a leak detection means for detecting the trace gas leaking from the one sealed space portion to the other sealed space portion; and a locking member that stops movement of the sealing member in a state of closing the opening portion.

Description

Leak inspection device and leak inspection method

Technical Field

The present invention relates to a leak inspection apparatus and a leak inspection method for detecting a leak in a workpiece by using a trace gas.

Background

For example, a hub for supporting a tire used in an automobile is required to be airtight because the hub supports the tire while sealing the air inside the tire. Generally, a hub is formed by casting and forging an aluminum casting, or in a combined hub, by welding or sealing a rim and a spoke by screwing. However, the hub has minute holes and cracks generated during casting, and air leakage due to poor welding occurs. Then, in order to reliably maintain airtightness of workpieces requiring airtightness, such as hubs (various workpieces such as cylinders, air-conditioning outdoor units, compressors, and fuel tanks for automobiles), leak inspection (leak test) using a tracer gas (inspection gas) is performed.

As a leak inspection apparatus for performing a leak inspection using this trace gas, for example, an apparatus disclosed in patent document 1 is known.

The leak inspection apparatus (leak test apparatus) described in patent document 1 includes: the sealing clamp is used for plugging the axial end part of the workpiece, namely the aluminum alloy hub; a container covering the aluminum alloy hub and the sealing jig; and a vacuum chamber. In patent document 1, the sealing jig has a sealing ring made of resin or rubber, and both ends in the axial direction of the aluminum alloy hub are sealed by the sealing ring. In this leak inspection apparatus, a helium gas and an air-mixed gas are supplied into the aluminum alloy hub space with both ends of the aluminum alloy hub in the axial direction sealed by a sealing jig, and the presence or absence of gas leakage is determined by detecting the gas leaking from the inside of the aluminum alloy hub into the vacuum chamber.

Patent document 1: japanese unexamined patent publication No. 2000-74777

In this way, in the leak inspection device described in patent document 1, the opening (opening) of the workpiece (aluminum alloy hub) is sealed by the flexible seal member (seal ring) formed of resin or rubber, and the state in which the sealed space portion on the inner side and the sealed space portion on the outer side of the workpiece are sealed can be maintained. In the leak inspection apparatus having such a configuration, as shown in fig. 6, a trace gas such as helium is supplied to the sealed space 11 on the inner side or the sealed space 12 on the outer side of the workpiece 20 (the sealed space 12 on the outer side in fig. 6), and the trace gas presses the seal member 31A to apply a reaction force f3 to return the seal member 31A. Therefore, in order to maintain the state in which the sealing

members

31A, 31B are in close contact with the opening portions 21A, 21B of the workpiece 20, it is necessary to apply a pressing force f1, which is larger than a pressing force required to seal the opening portions 21A, 21B of the workpiece 20 before the supply of the trace gas, that is, a resultant force of a force f2 by which the workpiece 20 presses the sealing member 31A to return and a reaction force f3 by the trace gas, to the workpiece 20 and the sealing member 31A in consideration of the reaction force f3 by the trace gas.

However, if the pressing force f1 is applied, the reaction force f3 by the trace gas is not generated at the initial stage of supplying the trace gas, and therefore, an excessive pressing force is applied to the workpiece, and a minute hole or crack to be inspected is deformed and sealed, and a problem arises that leakage cannot be detected reasonably. In addition, since an excessive pressing force is applied to the sealing member, there is also a problem that the sealing member is worn in a short time.

Disclosure of Invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide a leak inspection apparatus and a leak inspection method that can perform detection with high accuracy and can repeatedly use a seal member.

The leakage inspection device of the present invention is characterized by comprising: an inspection chamber capable of receiving a workpiece; a pressing member that seals the opening of the workpiece by pressing the sealing member in the inspection chamber so as to abut against the opening, thereby isolating the inspection chamber into a sealed space portion that is separated from each other on the inside and outside of the workpiece; a gas supply means for supplying a trace gas to the sealed space portion on one of the inner side and the outer side of the workpiece; a leak detection means for detecting the trace gas leaking from the one sealed space portion to the other sealed space portion; and a locking member that stops movement of the sealing member in a direction away from the workpiece, the sealing member being in a state of closing the opening.

In this leak inspection apparatus, when the sealing member is pressed into contact with the opening of the workpiece to separate the inside and outside of the workpiece into the sealed space sections, the pressing force applied to the sealing member and the workpiece can be set to a magnitude necessary to maintain the state of closing the opening, regardless of the reaction force (internal pressure) generated by supplying the trace gas to one of the sealed space sections. Further, by stopping the movement of the seal member in the direction away from the workpiece by the lock member before the supply of the trace gas to one of the sealed space portions, even if the trace gas is supplied to one of the sealed space portions and the reaction force by the trace gas is gradually increased, the state in which the opening portion is closed by the seal member can be maintained.

In this way, in the leak inspection apparatus, it is not necessary to apply an excessive pressing force to the workpiece in consideration of the reaction force by the trace gas in order to maintain the state of sealing the opening of the workpiece before the trace gas is supplied, and the minute holes, cracks, and the like to be inspected can be detected with high accuracy without being deformed and blocked. Further, since excessive pressing force is not applied to the seal member, abrasion of the seal member can be prevented, and the seal member can be used for a long period of time.

In the leak inspection device according to the present invention, it is preferable that the pressing member is formed by a hydraulic cylinder, and the lock member is formed by a valve that blocks a flow of fluid in the hydraulic cylinder.

Since the hydraulic cylinder uses incompressible oil as a fluid, the hydraulic cylinder can be maintained in a state in which the sealing member is pressed by the hydraulic cylinder to be in contact with the opening of the workpiece, and the valve is closed to cut off the flow of the fluid in the hydraulic cylinder. Therefore, even if a reaction force by the trace gas is generated, the seal member is not pushed back, and the state of sealing the opening of the workpiece can be maintained.

When a cylinder is used as the pressing member, the cylinder uses a compressible gas (air) as a fluid, and therefore, as in the case of pressing via a spring, there is a risk that the seal member is pushed back when a reaction force is applied to the tracer gas. Therefore, before the supply of the trace gas, it is necessary to apply a pressing force larger than a pressing force required to close the opening of the workpiece in consideration of the reaction force of the trace gas. In this case, an excessive pressing force is applied to the workpiece, and thus there is a possibility that a minute hole, a crack, or the like to be inspected is deformed and blocked.

In the leak inspection device according to the present invention, it is preferable that the pressing member includes a pressing plate portion that is brought into contact with the sealing member to press the sealing member, and the lock member includes a stopper member that is brought into contact with the pressing plate portion to stop movement of the sealing member in a direction away from the workpiece.

For example, in the case of using a cylinder as the pressing member, since the movement of the sealing member in the direction away from the workpiece is stopped by the stopper member, even if a reaction force by the trace gas is generated, the sealing member is not pushed back, and the state of sealing the opening of the workpiece can be maintained.

In a leak inspection method of the present invention, in an inspection chamber capable of accommodating a workpiece, a seal member is pressed to abut against an opening of the workpiece to close the opening, and in a state where an inside and an outside of the workpiece are separated into separate sealed space portions in the inspection chamber, a trace gas is supplied to one of the sealed space portions on the inside and the outside of the workpiece, and leakage of the trace gas from the one sealed space portion to the other sealed space portion is detected, the trace gas being supplied to the one sealed space portion in a state where movement of the seal member in a direction away from the workpiece in the state where the opening is closed is stopped.

According to the present invention, it is possible to detect leakage of a workpiece with high accuracy, and to use a seal member repeatedly for a long period of time.

Drawings

Fig. 1 is a schematic diagram showing a first embodiment of a leak inspection apparatus according to the present invention.

Fig. 2 is a schematic diagram showing a modification of the first embodiment.

Fig. 3 is a schematic diagram showing a leak inspection apparatus according to a second embodiment of the present invention.

Fig. 4 is a schematic diagram showing a leak inspection apparatus according to a third embodiment of the present invention.

Fig. 5 is a schematic view showing a fourth embodiment of the leak inspection apparatus of the present invention.

Fig. 6 is a schematic diagram showing a conventional leak inspection apparatus.

Description of the reference numerals

10 … inspecting the chamber,

11 … internal side sealed space portion (the other sealed space portion), 12 … external side sealed space portion (one sealed space portion), 13 … base portion, 14 … body portion, 15 … top portion, 16 … cylindrical portion, 17 … through hole, 20, 23, 25 … workpiece, 21A, 21B, 24, 26 … opening portion, 31A, 31B, 32 … sealing component, 40, 45 … pressing member, 41 … hydraulic cylinder, 42, 47 … shaft portion, 35, 43, 48 … pressing plate portion, 46, 81A, 81B … cylinder, 48a, 48B … engaging hole, 44A, 44B … hydraulic pressure source, 49, 84 … pneumatic pressure source, 51 … gas supply member, 52 … leakage detection member, 60, 70, 80, 90 … locking member, 61A, 61B …,

wedge

71, 75, 91 7 middle position closing valve, 82A, 82B …, 3683A, … B stopping component, 85 … two-way valve, 101S, 102, 103, 104 … leak check device.

Detailed Description

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

Fig. 1 shows a leak inspection apparatus 101 according to a first embodiment of the present invention. As shown in fig. 1, the leak inspection apparatus 101 disposes a cylindrical workpiece 20 having openings on both sides (upper and lower sides in fig. 1) in an inspection chamber 10 with the openings 21A and 21B of the workpiece 20 sealed by

seal members

31A and 31B, and detects a leak between a sealed space portion 11 on the inner side and a sealed space portion 12 on the outer side of the workpiece 20 by a trace gas. Specifically, helium is used as the tracer gas.

The leak inspection device 101 includes: an inspection chamber 10 capable of receiving a workpiece 20; a pressing member 40 that closes the openings 21A and 21B by pressing the

sealing members

31A and 31B into contact with the upper and lower openings 21A and 21B of the workpiece 20 in the inspection chamber 10, and that partitions the inspection chamber 10 into closed

space portions

11 and 12 separated from each other on the inner side and the outer side of the workpiece 20; a gas supply means 51 for supplying a trace gas to the sealed space 12 (one sealed space in the present invention) outside the workpiece 20; a leak detection means 52 for detecting a trace gas leaking from the sealed space 12 on the outside side to the sealed space 11 on the inside side (the other sealed space in the present invention); and a lock member 60 that stops the movement of the

seal members

31A and 31B in a direction away from the workpiece 20 in a state of closing the openings 21A and 21B of the workpiece 20.

In the leak inspection apparatus 101 of the present embodiment, the pressing member 40 is constituted by the hydraulic cylinder 41 and the pressing plate portion 43 attached to the shaft portion 42 thereof. The lock member 60 is configured by

stop valves

61A and 61B (valves in the present invention) provided between the hydraulic cylinder 41 constituting the pressing member 40 and the

hydraulic pressure sources

44A and 44B. The

shutoff valves

61A and 61B can switch between opening and closing of the flow path of the oil (fluid) between the hydraulic cylinder 41 and the

hydraulic sources

44A and 44B by switching between two positions of open and closed valves, and when the

shutoff valves

61A and 61B are set to the open position p12, the hydraulic cylinder 41 can be driven to move the pressing plate 43 up and down. On the other hand, when the

shutoff valves

61A, 61B are in the valve closing position p11, the flow of oil between the hydraulic cylinder 41 and the

hydraulic sources

44A, 44B is blocked, whereby the vertical movement of the pressing plate portion 43 can be stopped, and the pressing plate portion 43 can be kept in the current state.

The inspection chamber 10 is composed of a disk-shaped base 13 and an arch-shaped main body 14 placed on the base 13. The main body 14 of the inspection chamber 10 includes a disc-shaped ceiling portion 15 and a cylindrical portion 16 extending downward from the periphery of the ceiling portion 15. Although not shown, a seal member is attached between the base 13 and the body 14, and the inside of the inspection chamber 10 is sealed and isolated from the outside.

Further, a sealing member 31B for sealing the lower side of the lower side opening 21B of the workpiece 20 is attached to the upper surface of the base portion 13 of the inspection chamber 10. Further, a vent hole (not shown) is provided in the base portion 13 and the lower sealing member 31B, and a leakage detecting means 52 is connected through the vent hole.

The main body 14 of the inspection chamber 10 is provided with a through hole 17 into which the shaft 42 of the hydraulic cylinder 41 is inserted so as to be movable up and down, and the lower end of the shaft 42 protrudes into the inspection chamber 10 through the through hole 17 and is connected to the pressing plate 43. Although not shown, a bearing is provided in the through hole 17, and the shaft 42 is slidably fitted in the bearing, whereby the shaft 42 can be smoothly moved up and down. The shaft portion 42 is moved up and down by driving the hydraulic cylinder 41, and the pressing plate portion 43 can be moved up and down.

An upper seal member 31A is attached to the lower surface of the pressing plate portion 43, and the upper seal member 31A is provided so as to be movable up and down in accordance with the up-and-down movement of the pressing plate portion 43. The upper seal member 31A is provided to be movable up and down between the cylindrical portion 16 of the inspection chamber 10 and the seal member without causing air leakage. Therefore, the lower opening 21B of the workpiece 20 is placed on the lower sealing member 31B so as to face the lower sealing member 31B, the upper sealing member 31A is lowered by driving the hydraulic cylinder 41 in this state, the upper sealing member 31A is pressed into contact with the upper opening 21A of the workpiece 20, the upper and lower openings 21A and 21B of the workpiece 20 are sandwiched between the lower sealing member 31B and the upper sealing member 31A, and the upper opening 21A and the lower opening 21B of the workpiece 20 and the sealing member 31A, and the lower opening 21B and the sealing member 31B can be brought into close contact with each other. Then, by this close contact, the openings 21A and 21B of the workpiece 20 are closed by the

seal members

31A and 31B, the inside and the outside of the workpiece 20 are isolated, and the

closed space portions

11 and 12 are formed inside the inspection chamber 10.

In addition, a vent hole (not shown) is provided in the cylindrical portion 16 of the inspection chamber 10 constituting the sealed space 12 on the outside, and the vent hole is connected to a gas supply member 51 for supplying a trace gas for inspection.

Next, a method of performing a leak inspection of the cylindrical workpiece 20 using the leak inspection apparatus 101 configured in this manner will be described.

First, the lower opening 21B of the workpiece 20 is directed toward the lower sealing member 31B and placed on the lower sealing member 31B. Then, the hydraulic cylinder 41 is driven to move the pressing plate portion 43 and the upper seal member 31A downward, and the upper seal member 31A is pressed into contact with the upper opening 21A of the workpiece 20. Thus, the workpiece 20 is sandwiched between the lower seal member 31B and the upper seal member 31A, and the upper and lower openings 21A, 21B of the workpiece 20 are closed, whereby the inside and the outside of the workpiece 20 are isolated, and the

closed space portions

11, 12 are formed. At this time, the pressing force applied to the

sealing members

31A and 31B and the workpiece 20 is set to a magnitude necessary to maintain the state of sealing the upper and lower openings 21A and 21B of the workpiece 20, without taking into account the reaction force (internal pressure) generated by supplying the trace gas to the sealed space portion 12 on the outer side.

Then, before the trace gas is supplied to the sealed space portion 12 on the outside, the

shutoff valves

61A and 61B are closed, the vertical movement of the pressing plate portion 43 is stopped, the vertical movement of the sealing

members

31A and 31B in a state of closing the openings 21A and 21B of the workpiece 20 is stopped, and the movement of the sealing member 31A in a direction away from the workpiece 20 is stopped. Further, since the hydraulic cylinder 41 uses non-compressible oil as a fluid, the flow of oil (fluid) in the hydraulic cylinder 41 is cut off in a state where the

seal members

31A and 31B are pressed by the pressing plate portions 43 and brought into contact with the openings 21A and 21B of the workpiece 20, whereby the state of closing the openings 21A and 21B of the workpiece 20 can be maintained.

Next, the gas in the sealed

space portions

11 and 12 is discharged and reduced in pressure, and while the

openings

21a and 21b of the workpiece 20 are kept closed, the trace gas is supplied from the gas supply means 51 into the sealed space portion 12 on the outside, and the trace gas in the sealed space portion 11 on the inside is detected by the leak inspection means 52. Thus, if the trace gas is detected in the sealed space 11 on the inner side, it is determined that a defect such as a crack or a hole exists in the workpiece 20 and a leak has occurred, and if the trace gas is not detected, it is determined that a defect such as a crack or a hole does not exist in the workpiece 20 and a leak does not exist.

Further, after the trace gas is supplied into the sealed space 12 on the outside, the trace gas is filled into the sealed space 12 on the outside to increase the internal pressure, and although a reaction force by the trace gas is generated, since the

shutoff valves

61A and 61B are closed before the trace gas is supplied to block the flow of oil in the hydraulic cylinder 41, the upper seal member 31A and the pressing plate 43 are not pushed back by the reaction force of the trace gas, and the inspection can be performed stably.

After the leak inspection is completed, the interior of the inspection chamber 10 is returned to normal pressure, and the trace gas is discharged. Then, the

check valves

61A and 61B are opened, the hydraulic cylinder 41 is driven to move the pressing plate portion 43 upward, the inspected workpiece 20 is taken out from the inspection chamber 10, and the workpiece 20 is replaced with another non-inspected workpiece 20, whereby the leak inspection can be repeatedly performed on the plurality of workpieces 20.

In this way, in the leak inspection apparatus 101 of the present embodiment, by closing the

shutoff valves

61A and 61B in advance and stopping the movement of the seal member 31A in the direction away from the workpiece 20, even when the trace gas is supplied to the sealed space portion 12 on the outer side and the reaction force by the trace gas is gradually increased, the state of closing the openings 21A and 21B of the workpiece 20 can be maintained by the

seal members

31A and 31B.

Therefore, in the leak inspection apparatus 101, in order to maintain the state of closing the openings 21A and 21B of the workpiece 20 by the

seal members

31A and 31B before the supply of the trace gas, an excessive pressing force is not applied to the workpiece 20 in consideration of the reaction force by the trace gas, and therefore, the minute holes, cracks, and the like to be inspected are not deformed and closed, and the leak can be detected with high accuracy. Further, since excessive pressing force is not applied to the

seal members

31A and 31B, it is possible to prevent the

seal members

31A and 31B from being worn, and to use the

seal members

31A and 31B continuously for a long period of time.

In the leak inspection apparatus 101 shown in fig. 1, the sealing

members

31A and 31B separated from each other are brought into close contact with the opening portions 21A and 21B at both ends of the workpiece 20 to close the same, but in the case of inspecting a bottomed workpiece 23 in which one opening portion is closed as in the leak inspection apparatus 101S shown in fig. 2, the sealing member 31A for closing the opening portion 24 at one portion of the workpiece 23 may be provided in advance, and the lower sealing member may be omitted.

Fig. 3 shows a leak inspection apparatus 102 according to a second embodiment of the present invention. In the leak inspection apparatus 102, similarly to the leak inspection apparatus 101 of the first embodiment, the workpiece 20 is arranged in the inspection chamber 10 with the opening portions 21A and 21B of the cylindrical workpiece 20 having opening portions on both sides (upper and lower sides in fig. 3) sealed by the

seal members

31A and 31B, and the leak between the sealed space portion 11 on the inner side and the sealed space portion 12 on the outer side of the workpiece 20 is detected by the trace gas. Note that, in the leak inspection apparatus 102 of the second embodiment, the same reference numerals are given to elements common to the leak inspection apparatus 101 of the first embodiment, and the description thereof is omitted, as is the case with the leak inspection apparatus 103 of the third embodiment and the leak inspection apparatus 104 of the fourth embodiment which will be described later.

In the leak inspection apparatus 102, the structures of the inspection chamber 10, the pressing member 40, the gas supply member 51, and the leak detection member 52 are the same as those of the leak inspection apparatus 101 according to the first embodiment, but the lock member 70 is configured by a middle position closing valve 71 (a valve in the present invention) provided between the hydraulic cylinder 41 configuring the pressing member 40 and the hydraulic pressure source 44. The middle position closing valve 71 switches between one-position valve closing and two-position valve opening at three positions in total, and as shown in fig. 3, at the central valve closing position p22, the flow of oil between the hydraulic cylinder 41 and the hydraulic source 44 is cut off, and the vertical movement of the pressing plate portion 43 is stopped, whereby the movement of the seal member 31A in the direction away from the workpiece 20 can be stopped. When the center position closing valve 71 is in the left valve opening position p21 in fig. 3, the oil flows from the hydraulic source 44 into the upper space of the hydraulic cylinder 41 and returns from the lower space to the hydraulic source 44, and the shaft portion 42 can be moved downward, and the pressing plate portion 43 and the seal member 31A can be advanced toward the workpiece 20. On the other hand, when the center position closing valve 71 is in the valve opening position p23 on the right side in fig. 3, the oil flows from the hydraulic source 44 into the lower space of the hydraulic cylinder 41 and returns from the upper space to the hydraulic source 44, whereby the shaft portion 42 can be moved upward, and the pressing plate portion 43 and the seal member 31A can be retracted from the workpiece 20.

In the leak inspection apparatus 102 according to the second embodiment, when the hydraulic cylinder 41 is driven and the opening portions 21A and 21B of the workpiece 20 are closed by the

seal members

31A and 31B, the intermediate position closing valve 71 is set to the valve opening position p21, and the pressing plate portion 32 and the upper seal member 31A are moved downward. Then, the sealing

members

31A and 31B are pressed into contact with the opening portions 21A and 21B of the workpiece 20, and after the opening portions 21A and 21B are closed, the middle position closing valve 71 is set to the valve closing position p22 to stop the downward movement of the pressing plate portion 43 and the upper sealing member 31A, and the state where the opening portions 21A and 21B are closed by the sealing

members

31A and 31B is maintained. At this time, the pressing force applied to the

sealing members

31A and 31B and the workpiece 20 is set to a magnitude necessary to maintain the state of sealing the upper and lower openings 21A and 21B of the workpiece 20, regardless of the reaction force (internal pressure) generated by supplying the trace gas to the sealed space portion 12 on the outside.

In the leak inspection apparatus 102 according to the second embodiment, even if the reaction force by the trace gas is gradually increased by supplying the trace gas to the sealed space portion 12 on the outer side, the up-and-down movement of the pressing plate portion 43 can be stopped and the movement of the seal member 31A can be stopped by setting the middle position closing valve 71 to the valve closing position p22, and therefore, the state of sealing the opening portions 21A and 21B of the workpiece 20 can be maintained by the

seal members

31A and 31B.

Therefore, in the leak inspection apparatus 102, similarly to the leak inspection apparatus 101 of the first embodiment, since an excessive pressing force is not applied to the workpiece 20 in consideration of the reaction force by the trace gas in order to maintain the state in which the opening portions 21A and 21B of the workpiece 20 are sealed by the sealing

members

31A and 31B before the trace gas is supplied, minute holes, cracks, and the like to be inspected are not deformed and are closed, and detection can be performed with high accuracy. Further, excessive pressing force is not applied to the

seal members

31A and 31B, so that abrasion of the

seal members

31A and 31B can be prevented, and the

seal members

31A and 31B can be used for a long period of time.

Fig. 4 shows a leak inspection apparatus 103 according to a third embodiment of the present invention. The leak inspection apparatus 103 is similar to the leak inspection apparatus 101 of the first embodiment and the leak inspection apparatus 102 of the second embodiment, and the work 20 is disposed in the inspection chamber 10 with the opening portions 21A and 21B of the cylindrical work 20 having opening portions on both sides (upper and lower in fig. 4) sealed by the sealing

members

31A and 31B, and a leak between the sealed space portion 11 on the inner side and the sealed space portion 12 on the outer side of the work 20 is detected by a trace gas. The structure of the inspection chamber 10, the gas supply member 51, and the leak detection member 52 of the leak inspection apparatus 103 according to the third embodiment is the same as that of the leak inspection apparatus 101 according to the first embodiment, but the pressing member 45 is composed of the cylinder 46 and the pressing plate portion 48 attached to the shaft portion 47, and the locking member 80 that stops the movement of the seal member 31A in the direction away from the workpiece 20 is composed of

wedge mechanisms

83A and 83B, and the

wedge mechanisms

83A and 83B are realized by the engagement of the engagement holes 48a and 48B formed in the pressing plate portion 48 and the

shaft portions

82A and 82B (stopper means in the present invention) of the

cylinders

81A and 81B attached to the main body portion 14 of the inspection chamber 10. That is, the leak inspection apparatus 103 according to the third embodiment is significantly different from the first and second embodiments in that the lock member 80 is formed by a mechanical member.

The air cylinder 46 constituting the pressing member 45 is connected to the air pressure source 49 via the center position closing valve 75, and as shown in fig. 4, the air flow between the air cylinder 46 and the air pressure source 49 is blocked at the center valve closing position p32, and the vertical movement of the pressing plate portion 48 can be stopped. When the center position closing valve 75 is in the valve opening position p31 on the left side in fig. 4, air flows from the air pressure source 49 into the upper space of the air cylinder 46 and returns to the air pressure source 49 from the lower space, whereby the shaft portion 47 can be moved downward and the pressing plate portion 48 can be moved forward toward the workpiece 20. When the center position closing valve 75 is in the valve opening position p33 on the right side in fig. 4, air flows from the air pressure source 49 into the lower space of the air cylinder 46 and returns from the upper space to the air pressure source 49, whereby the shaft portion 47 can be moved upward and the pressing plate portion 48 can be retracted from the workpiece 20.

Further, as described above, the

wedge mechanisms

83A and 83B constituting the lock member 80 are constituted by the engagement holes 48a and 48B formed in the pressing plate portion 48 and the

shaft portions

82A and 82B of the

air cylinders

81A and 81B, and the pressing plate portion 48 can be fixed and stopped from moving up and down by engaging the

shaft portions

82A and 82B with the engagement holes 48a and 48B, respectively. On the other hand, in a state where the

shaft portions

82A and 82B of the

cylinders

81A and 81B are pulled out from the engagement holes 48a and 48B, the pressing plate portion 48 and the seal member 31A can move up and down in accordance with the driving of the cylinder 46 constituting the pressing member 45.

Further, the

air cylinders

81A, 81B constituting the

wedge mechanisms

83A, 83B are connected to the air pressure source 84 via the two-way valve 85, and when the air cylinders are in the left valve opening position p41 as shown in fig. 4, air flows from the air pressure source 84 into the outer peripheral side space of the

air cylinders

81A, 81B, and returns from the inner peripheral side space to the air pressure source 84, whereby the

shaft portions

82A, 82B move toward the inner peripheral side, and the engagement with the engagement holes 48a, 48B of the pressing plate portion 48 can be maintained, whereby the vertical movement of the pressing plate portion 48 can be stopped, and the movement of the seal member 31A in the direction away from the workpiece 20 can be stopped. On the other hand, when the two-way valve 85 is in the valve opening position p42 on the right side in fig. 4, air flows from the air pressure source 84 into the inner peripheral side space of the

cylinders

81A and 81B and returns to the air pressure source 84 from the outer peripheral side space, whereby the

shaft portions

82A and 82B are moved toward the outer peripheral side, and the tips of the

shaft portions

82A and 82B are pulled out from the engagement holes 48a and 48B of the pressing plate portion 48, whereby the restraint by the

shaft portions

82A and 82B is released, and the sealing member 31A can be moved up and down together with the pressing plate portion 48.

In the leak inspection apparatus 103 according to the third embodiment, when the opening portions 21A and 21B of the workpiece 20 are closed by the

seal members

31A and 31B, the two-way valve 85 is set to the valve opening position p42 in advance, and the

shaft portions

82A and 82B of the

wedge mechanisms

83A and 83B are retracted to the outer peripheral side. Then, the center position closing valve 75 is set to the valve opening position p31, and the pressing plate portion 48 and the upper seal member 31A are moved downward. Then, the sealing

members

31A and 31B are pressed into contact with the opening portions 21A and 21B of the workpiece 20, and after the opening portions 21A and 21B are closed, the middle position closing valve 75 is set to the valve closing position p32 to stop the vertical movement of the pressing plate portion 48 and the upper sealing member 31A, and the state where the opening portions 21A and 21B are closed by the sealing

members

31A and 31B is maintained. At this time, the pressing force applied to the

sealing members

Before the trace gas is supplied to the sealed space 12 on the outer side, the two-way valve 85 is set to the valve-opening position p41, whereby the

shaft portions

82A and 82B of the

wedge mechanisms

83A and 83B are moved to the inner peripheral side, the engagement holes 48a and 48B of the pressing plate portion 48 are engaged with the

shaft portions

82A and 82B, and the vertical movement of the pressing plate portion 48 and the seal member 31A is stopped.

In the leak inspection apparatus 103, the air cylinder 46 is used as the pressing member 45, but since the air cylinder 46 uses a gas (air) having compressibility as a fluid, the same is true as in the case of pressing the

seal members

31A and 31B via springs. Therefore, when the reaction force by the trace gas is received, the air in the upper space of the cylinder 46 is compressed, and the pressing plate portion 48 and the upper seal member 31A may be pushed back in the direction away from the workpiece 20. However, in the leak inspection device 103 according to the third embodiment, the

wedge mechanisms

83A and 83B are provided as the lock members 80, and the vertical movement of the pressing plate portion 48 is stopped by a mechanical member. In this way, by engaging the

shaft portions

82A and 82B constituting the

wedge mechanisms

83A and 83B with the engagement holes 48a and 48B before the supply of the trace gas, even when the trace gas is filled into the sealed space portion 12 on the outside and the internal pressure is increased to generate a reaction force by the trace gas, the movement of the pressing plate portion 48 in the direction away from the workpiece 20 can be stopped by bringing the

shaft portions

82A and 82B into contact with the engagement holes 48a and 48B. Therefore, the upper seal member 31A and the pressing plate 48 are not pushed back by the reaction force of the trace gas, and the inspection can be performed stably.

In fig. 4, two

wedge mechanisms

83A and 83B are illustrated, but the locking member may be configured by three or more wedge mechanisms. In this case, since the reaction force by the tracer gas is dispersed to each wedge mechanism, it is preferable that each wedge mechanism is disposed at equal intervals in the circumferential direction of the pressing plate portion 48.

After the leak inspection is completed, the two-way valve 85 is set to the valve opening position p42, the

shaft portions

82A and 82B are moved toward the outer peripheral side, and the engagement between the

shaft portions

82A and 82B and the engagement holes 48a and 48B is released. Then, the center position closing valve 75 is set to the valve opening position p33, and the air cylinder 46 is driven to move the pressing plate portion 48 upward.

In this way, in the leak inspection apparatus 103 according to the third embodiment, even when the reaction force by the trace gas is gradually increased by supplying the trace gas to the sealed space portion 12 on the outer side, the

wedge mechanisms

83A and 83B can stop the vertical movement of the pressing plate portion 48 and stop the movement of the seal member 31A in the direction away from the workpiece 20, and therefore the state of sealing the opening portions 21A and 21B of the workpiece 20 can be maintained by the

seal members

31A and 31B.

Therefore, in the leak inspection apparatus 103, similarly to the leak inspection apparatus 101 of the first embodiment and the leak inspection apparatus 102 of the second embodiment, when the opening portions 21A and 21B of the workpiece 20 are sealed by the

seal members

31A and 31B before the supply of the trace gas, an excessive pressing force in consideration of the reaction force by the trace gas is not applied to the workpiece 20, and therefore, the minute holes, cracks, and the like to be inspected are not deformed and sealed, and can be detected with high accuracy. Further, since excessive pressing force is not applied to the

seal members

31A and 31B, abrasion of the

seal members

31A and 31B can be prevented, and the

seal members

31A and 31B can be used for a long period of time.

In the third embodiment, the vertical movement of the seal member 31A is stopped by engaging the

shaft portions

82A, 82B of the stopper member with the engaging holes 48a, 48B of the pressing plate portion 48, but the movement of the pressing plate portion 48 and the seal member 31A in the direction away from the workpiece 20 may be stopped by bringing the

shaft portions

82A, 82B into contact with the back surface of the pressing plate portion 48 (the surface opposite to the mounting surface of the seal member 31A).

In the third embodiment, the

air cylinders

81A and 81B are used as members for driving the

wedge mechanisms

83A and 83B of the locking member 80, but the present invention is not limited thereto, and for example, the

shaft portions

82A and 82B may be moved by another power source such as a motor. Further, the locking member may be configured by a mechanical member other than the wedge mechanism.

Fig. 5 shows a leak inspection apparatus 104 according to a fourth embodiment. In the leak inspection apparatuses 101 to 103 according to the first to third embodiments, the cylindrical workpiece 20 having the opening

portions

21a and 21b on both sides is used as an inspection target, but the workpiece is not limited thereto, and a leak inspection of a workpiece 25 having an opening portion 26 at one location, such as a gas cylinder, can be performed as shown in fig. 5.

In the leak inspection apparatus 104 according to the fourth embodiment, the pressing member 40 is constituted by the hydraulic cylinder 41 and the pressing plate portion 35 attached to the shaft portion 42 thereof. The lock member 90 is constituted by a center position closing valve 91 (valve in the present invention) provided between the hydraulic cylinder 41 constituting the pressing member 40 and the hydraulic pressure source 44. In this case, as shown in fig. 5, when the center-position closing valve 91 is at the central valve-closing position p52, the flow of oil between the hydraulic cylinder 41 and the hydraulic source 44 is interrupted, and the forward and backward movement of the pressing plate portion 35 is stopped. When the center position closing valve 91 is in the left valve opening position p51 in fig. 5, the oil flows from the hydraulic source 44 into the left space of the hydraulic cylinder 41 and returns from the right space to the hydraulic source 44, whereby the shaft portion 42 is moved to the right side, and the pressing plate portion 35 can be moved forward toward the workpiece 25. When the center position closing valve 91 is in the valve opening position p53 on the right side in fig. 5, the oil flows from the hydraulic source 44 into the right space of the hydraulic cylinder 41 and returns from the left space to the hydraulic source 44, whereby the shaft portion 42 is moved to the left side, and the pressing plate portion 35 can be retracted from the workpiece 25.

In the leak inspection apparatus 104 according to the fourth embodiment, when the hydraulic cylinder 41 is driven and the opening 26 of the workpiece 25 is closed by the seal member 32, the center position closing valve 91 is set to the valve opening position p51, and the pressing plate portion 35 and the seal member 32 are moved forward. Then, the sealing member 32 is pressed to abut against the opening 26 of the workpiece 25, and after the opening 26 is closed, the center stop valve 91 is set to the valve closing position p52 to stop the forward and backward movement of the pressing plate portion 35 and the sealing member 32, and the state where the opening 26 is closed by the sealing member 32 is maintained. At this time, the pressing force applied to the seal member 32 and the workpiece 25 is set to a magnitude necessary to maintain the state of sealing the opening 26 of the workpiece 25, regardless of the reaction force (internal pressure) generated by supplying the trace gas to the sealed space portion 12 on the outside.

Further, although the trace gas is filled into the sealed space 12 on the outside side after the trace gas is supplied into the sealed space 12 on the outside side to increase the internal pressure and generate a reaction force by the trace gas, the pilot valve 91 is closed before the trace gas is supplied to cut off the flow of oil in the hydraulic cylinder 41, so that the seal member 32 and the pressing plate portion 35 are not pushed back by the reaction force of the trace gas, and the inspection can be performed stably.

In this way, in the leak inspection apparatus 104 according to the fourth embodiment, by setting the middle position closing valve 91 at the valve closing position p52 in advance, even when the trace gas is supplied to the sealed space portion 12 on the outer side and the reaction force by the trace gas is gradually increased, the advancing and retreating movement of the pressing plate portion 35 can be stopped, the movement of the seal member 32 in the direction away from the workpiece 25 can be stopped, and the state in which the opening 26 of the workpiece 25 is closed by the seal member 32 can be maintained.

Therefore, in the leak inspection apparatus 104, similarly to the leak inspection apparatuses 101 to 103 according to the first to third embodiments, since an excessive pressing force is not applied to the workpiece 26 in consideration of the reaction force by the trace gas before the trace gas is supplied in order to maintain the state of closing the opening 26 of the workpiece 25 by the seal member 32, the minute holes, cracks, and the like to be inspected are not deformed and closed, and can be detected with high accuracy. Further, since an excessive pressing force is not applied to the seal member 32, the seal member 32 can be prevented from being worn, and the seal member 32 can be used for a long period of time.

In the leak inspection apparatuses 101 to 104, the trace gas is supplied to the sealed space portion on the outside and the trace gas leaking from the sealed space portion on the outside to the sealed space portion on the inside is detected, but the trace gas may be supplied to the sealed space portion on the inside and the trace gas leaking from the sealed space portion on the inside to the sealed space portion on the outside is detected.

The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

Claims

1. A leak inspection device is characterized by comprising:

an inspection chamber capable of receiving a workpiece;

a pressing member that seals an opening of the workpiece in the inspection chamber by pressing the sealing member into contact with the opening, and separates the inspection chamber into a sealed space portion on an inner side and an outer side of the workpiece;

a gas supply means for supplying a trace gas to the sealed space portion on one of the inner side and the outer side of the workpiece;

a leak detection means for detecting the trace gas leaking from the one sealed space portion to the other sealed space portion;

a lock member that stops movement of the seal member in a direction away from the workpiece, the seal member being in a state of closing the opening;

the lock member stops movement of the seal member before the supply of the trace gas in a state where a pressing force applied to the seal member by the pressing member is larger than a force by which the work presses and returns the seal member and smaller than a resultant force of a reaction force by which the trace gas presses and returns the seal member and the force.

2. The leak inspection device according to claim 1,

the pressing member is configured by a hydraulic cylinder, and the lock member is configured by a valve that stops a flow of fluid in the hydraulic cylinder.

3. The leak inspection device according to claim 1,

the pressing member includes a pressing plate portion that is pressed by abutting against the sealing member,

the locking member has a stopper member that abuts against the pressing plate portion to stop the movement of the sealing member in a direction away from the workpiece.

4. A method for checking a leak of a fluid,

in an inspection chamber capable of accommodating a workpiece,

the opening of the work is closed by pressing a sealing member so as to abut against the opening, and the inspection chamber is isolated into a sealed space portion which is separated from each other on the inner side and the outer side of the work,

supplying a trace gas to the sealed space portion on one of the inner side and the outer side of the workpiece,

detecting leakage of the trace gas from the one sealed space portion to the other sealed space portion,

the method of leak checking is characterized in that,

in a state where a pressing force applied to the sealing member for closing the opening is larger than a force for pressing and returning the sealing member by the work and smaller than a resultant force of a reaction force for pressing and returning the sealing member by the trace gas and the force, movement of the sealing member in a direction away from the work is stopped, and the trace gas is supplied to the one sealed space portion.