JPH08304215A - Method and device for inspecting airtightness - Google Patents

Abstract

PURPOSE: To provide a method and device for inspecting airtightness by which the airtight part of a cylindrical work can be inspected for leakage with high accuracy. CONSTITUTION: In a method for inspecting airtightness, a space S sealing the airtight part to be inspected for leakage of a cylindrical work 1 is formed of the inner peripheral surface of a capsule and outer peripheral surface of the work 1 by surrounding the airtight part of the work 1 having at least one opened end with the capsule 5 and the interior of the sealed space S is evacuated. At the same time, high-pressure air is supplied to the work 1 through the opened end of the work 1 and, while the high-pressure air is supplied, the pressure in the space S is detected. A device for inspecting airtightness is provided with a sealed space forming section 2 which forms the space S by surrounding the airtight part of the work 1, evacuating source which evacuates the interior of the space S, air supplying section 3 which supplies the high-pressure air into the work 1, and pressure detecting section 4 which detects the pressure in the space S.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an airtightness inspection method and apparatus for inspecting airtightness of a cylindrical work.

[0002]

2. Description of the Related Art As a hollow work in which a plurality of tubular members are joined and integrated by welding or the like, there is an injector used for gasoline injection, for example. It is very dangerous for gasoline to pass through the inside of the injector and leak from the joint to the outside.Therefore, the injector should be securely joined, and after the manufacture, especially the gasoline should never leak to the outside. It is necessary to check the leaktightness of

In the airtightness test, for example, there is a submergence test in which the injector is immersed in water to supply air into the hollow, and air leakage is inspected over the entire number by observing how bubbles are generated at the joint. Alternatively, a high-pressure air is supplied into the hollow of the work by using a commercially available leak tester (leakage inspection device), the pressure fluctuation in the hollow of the work is detected, the degree of airtightness of the joint is detected, and all the air leaks are inspected. Is also known.

[0004]

An object of the present invention is to perform an airtightness inspection of a joint portion of a hollow work in which a plurality of cylindrical members are coaxially joined and integrated. Since it has to be immersed in water and dried, it takes time and labor to reduce productivity, and in the case of a leak tester, high pressure inspection accuracy can be obtained because the pressure fluctuation in the hollow of the workpiece is observed. There is no point.

[0005]

The present invention provides, as a method,
A hermetically sealed leak detecting portion of a cylindrical work having at least one open end is surrounded by a capsule to form a space for hermetically sealing the hermetic leak detecting portion with the inner peripheral surface of the capsule and the outer peripheral surface of the workpiece. Along with vacuum suction, high-pressure air is supplied into the work from the opening end, and the pressure of the closed space is detected in that state,

Further, as the apparatus, a closed space forming portion which forms a closed space by surrounding an airtight leak detection portion of a cylindrical work having at least one open end, and a vacuum suction source which vacuum-sucks the inside of the closed space. An air supply unit for supplying high-pressure air into the work and a pressure detection unit for detecting the pressure in the closed space are provided.

[0007]

According to the above technical means, the airtight leak detecting portion of the cylindrical work is surrounded by the capsule, and the inner peripheral surface of the capsule, the work outer peripheral surface, and the pair of elastic rings form a closed space of the airtight leak detecting portion. . And vacuum suction inside the closed space,
Moreover, high-pressure air is supplied into the hollow of the work to detect the pressure in the closed space.

[0008]

Embodiments of an airtightness inspection method and apparatus according to the present invention will be described below with reference to FIGS. Figure 1
In (a) and (b), (1) is a hollow work, (2) is a closed space forming part, (3) is an air supply part, and (4) is a pressure detection part. As shown in FIG. 2 (b), the work (1) is integrally formed by welding a cylindrical member (1 a) having an internally penetrating shape and two short and long cylindrical members (1 b) (1 c) opened vertically. Injector that has been made into a joint, and joints (1d) at the middle and bottom
(1e) and open end (1f).

The closed space forming part (2) comprises a cylindrical capsule (5), a pair of elastic O-rings (6a) (6b) and a pressing part (7). The capsule (5) is shown in FIG.
As shown in (b) and FIG. 2 (a) (however, the right half surface is before pressurization and the left half surface is after pressurization), the three tubular parts (5a) (5b) (5
c) is arranged coaxially, and O-rings (6a) (6b) are placed between the cylinders.
The nipping portions (5d) and (5e) are formed, and the nipping interval is regulated by spacers (8) having a diameter slightly smaller than the 0 ring. Moreover, a vacuum suction hole (5f) is formed on the side wall of the tubular portion (5b) {Fig. 1 (a)
See {1} and connect with the capsule (5) (1d)
Surround (1e). The O-rings (6a) and (6b) are elastic rings having an inner diameter slightly larger than the outer diameter of the work, and are housed in the holding portions (5d) and (5e) in a deformable manner under pressure, and the inner peripheral surface of the capsule (5). The joints (1d) and (1e) are sandwiched between the work (1) and the outer peripheral surface of the work (1) so as to be separated from each other. The pressurizing unit (7) includes a cylindrical pressurizing shaft (9) and a pressurizing cylinder (19).
And pressurizing the capsule (5) in the axial direction (A) of the work, and the O-rings (6a) (6) via the holding parts (5d) (5e).
b) is elastically deformed and the O-rings (6a) and (6b) are expanded in the direction (B) orthogonal to the work axis. And the O-ring (6
A) (6b) is brought into close contact with the inner peripheral surface of the capsule and the outer peripheral surface of the work to form a closed space (S) for sealing the joints (1d) (1e).

The air supply unit (3) comprises a cylindrical housing jig (10) and an air supply source (not shown). The storage jig (10) has a through hole (10a) for air supply and work storage, and stores and conveys the work (1) in the through hole (10a).
It is coaxially arranged below the capsule (5) in the examination position. The air supply source (not shown) includes a supply nozzle (11), a pipe (12), a valve (13), and a pressure increasing valve (1) shown in FIG.
4) and the like are connected to the through hole (10a) of the storage jig (10). When supplying high-pressure air, the supply nozzle (11) is pressed against the through-hole (10a) of the storage jig (10) from below to connect the high-pressure air from the open end (1f) into the hollow of the work (1). To supply.

The pressure detection unit (4) is a differential pressure sensor type leak tester which is connected to the vacuum suction hole (5f) of the capsule (5), and is a closed space (S) of the joints (1d) (1e) of the work (1). ) Is detected by the differential pressure sensor (15), and the airtightness of the joints (1d) and (1e) is inspected. The differential pressure sensor (15) has first and second partition chambers (U) and (V) partitioned by a diaphragm (D), and the inside of the first partition chamber (U) is set to a standard vacuum state without any leakage. Hold.
Further, the second partition chamber (V) is communicated with the closed space (S) to suck both of them, and the pressure of the second partition chamber (V) is compared with the reference vacuum of the first partition chamber (U). The distortion of the diaphragm (D) due to the pressure difference between the two is detected to detect the internal pressure fluctuation in the closed space (S).

A vacuum suction source (vacuum pump) (P) is connected to a second valve through valves (air operated valves) (16) (17) (18).
Vacuum suction hole (5f) of partition chamber (V) and capsule (5)
Is connected in series to the closed space (S) and the second partition chamber (V) by vacuum suction, and through the valve (17) to the arrow (Q). Incidentally, (Ma) and (Mb) are high pressure and vacuum pressure gauges, respectively.

The operation (airtightness inspection method) of the present invention based on the above configuration will be described below. First, in a joining process, three cylindrical members (1a) (1b) (1c) are welded and integrated to manufacture a work (1), which is then stored in a storage jig (10) and conveyed to an inspection position. Therefore, the capsule (5) is lowered at that position to accommodate the work (1) in a free state, and the joints (1d) (1e) are surrounded with a certain clearance. Next, the pressurizing unit (7) is moved down to the storage jig (10).
When the capsule (5) is sandwiched between and to pressurize in the work axis direction (A), the O-rings (6a) and (6b) are elastically deformed in a recoverable manner and pushed in the direction (B) orthogonal to the work axis. At this time, the cylinder pressurization amount (O-ring deformation amount) is regulated by the spacers (8) in the capsule (5), and the O-rings (6a) (6b) are also regulated by the spacers (8). And spread more to the work side. Then, the O-ring (6a) (6
The b) protrudes from the sandwiching portions (5d) and (5e) and comes into elastic contact with the outer peripheral surface of the work to come into close contact therewith to form a closed space (S) for sealing the joint portions (1d) and (1e).

Next, the closed space (S) is evacuated to a vacuum pump (P).
Vacuum suction to about 300 mmHg through the pressure detection part (4) and the open end (1) by the air supply part (3).
From f), high-pressure air of about 9 kg / cm ² is supplied into the hollow of the work. Then, in order to maintain the equilibrium state, after the vacuum suction and the air supply are stopped, the pressure in the closed space (S) is detected by the pressure detection unit (4). Therefore, the joint (1d) (1
If air leaks from e), the pressure related to the detection will change greatly from the vacuum, which will cause the joint (1d) (1
The airtightness can be checked by detecting the amount of air leakage in e). Moreover, since a pressure change in the closed space (S) is detected in a vacuum state, even a slight air leak amount can be detected, high inspection accuracy can be realized, and airtight leak can be detected reliably. Further, the higher the degree of vacuum in the closed space (S) or the higher the high-pressure air pressure in the hollow of the work, the more the pressure change that can be inspected occurs in a short time. It can be done. Further, although the time required for the inspection is conventionally in minutes, it is very short in the range of several seconds to several tens of seconds, and it does not take time and effort.

In practice, when high pressure air is supplied to the storage jig (10) without the work (1), the vacuum pump (P)
Is damaged due to overload, so before the high-pressure air supply in this inspection, the hollow space inside the work is at atmospheric pressure and the closed space (S)
Is vacuumed to detect the pressure. This detects whether or not the work is stored, and at the same time, the joint (1
d) Preliminary inspection for major leaks in (1e) and breakage of O-rings (6a) (6b). Then, in the above-mentioned main inspection, vacuum suction is performed to supply high-pressure air, and minute air leakage is detected.

Next, the general construction of the above airtightness inspection apparatus will be described with reference to FIG. In the figure, (1) is a cylindrical work,
(5) Capsule, (9) Cylindrical Pressure Shaft, (19)
Is a pressure cylinder, and (10) is a storage jig. The work (1) is an injector, and after welding and integration, the storage jig (1
0) Store inside and transport. The capsule (5) has a vacuum suction hole (5f) on the side wall, and is connected to a vacuum suction source (not shown) via the nozzle (20) and the pressure detection unit to be vacuum-sucked. The pressure shaft (9) is connected to a pressure cylinder (19) which will be described later and moves up and down above the capsule to pressurize the capsule (5) from above. Further, inside the pressure shaft (9), a lid body (21) having urethane rubber (Gb) attached to the lower end and a spring (22) for urging the lid body (21) downward are disposed. During pressurization, the upper surface of the work (1) is elastically contacted with the upper end surface of the work (1) stored in the storage jig (10) to close the upper surface of the work (1) to prevent leakage of high-pressure air supplied to the inside. The pressure cylinder (19) is a cylinder tube (19) fixed to the base plate (23).
The cylinder shaft (19b) is inserted into a) and the pressure shaft (9) is connected to the movable part (19c) connected to the lower end of the cylinder shaft. The linear guide (24) is provided on the right side of the movable part (19c). To provide. Then, the linear guide (24) is fitted to the guide rail (25) fixed to the base plate (23), and the movable portion (19c) is
Up and down.

A linear guide (26) is also provided on the side portion of the capsule (5) to be fitted on the guide rail (25), and a cam follower is laterally attached to the connecting shaft of the linear guide (26). Project the hook (27). Then, an elongated hole (not shown) is provided in the L-shaped plate (28) fixed to the pressure shaft (9), and a hook (27) is hooked on the elongated hole so that the capsule (5) can be guided vertically. ·Hold. or,
The L-shaped plate (28) is connected and held to the base plate (23) via a spring (29).

According to the above construction, when the storage jig (10) is transported to the inspection position, the pressure cylinder (19) is lowered, and the pressure shaft (9) resists the spring (29) to move the movable part ( 19c) and descend. Then, the capsule (5) fits over and surrounds the work (1) and is locked by the upper end surface of the storage jig (10). Therefore, pressurizing cylinder (19)
When is further lowered, the hook (27) plays in the elongated hole of the L-shaped plate (28) and the capsule (5) stops. Then, only the pressurizing shaft (9) descends and the lower end of the tubular shape contacts the upper end surface of the capsule (5) to pressurize the capsule (5) with the cylinder output pressure. So, as mentioned above,
The O-rings (6a) and (6b) elastically deform in the lateral direction to form a closed space (S). At the same time, the urethane rubber (Gb) of the lid body (21) elastically contacts the upper surface of the cylindrical work (1) to close the lid, thereby preventing leakage of high-pressure air supplied to the inside. Thereafter, similarly to the above, the inside of the closed space is vacuum-sucked, and high pressure air is supplied into the hollow of the work to detect the pressure in the closed space (S), and the airtight leak property of the joint is inspected. In the above-described embodiments, the joining portion of the tubular ark is shown as the airtight leak detecting portion, but the invention is not limited to this, and the member main body of the tubular work may be used.

[0019]

According to the present invention, a space for hermetically sealing the airtight leak detecting portion of a cylindrical work from the outside is formed, the interior is vacuum-sucked, and high pressure air is supplied into the hollow of the work to provide a hermetically sealed space. Since the pressure of the
In a short time of several tens of seconds, the airtightness of the work can be easily inspected to improve the productivity and workability, and the inspection accuracy is greatly improved because the inspectable pressure changes in a few seconds.

[Brief description of drawings]

FIG. 1A is a schematic side view of an essential part showing an embodiment of an airtightness inspection device according to the present invention. (B) is a principal part side view of the closed space formation part which concerns on this invention.

FIG. 2A is a side view showing a general configuration of a sealed space forming portion according to the present invention. (B) is a side sectional view of an injector which is an example of a hollow work.

FIG. 3 is a side view showing a general configuration of an embodiment of the airtightness inspection device according to the present invention.

[Explanation of symbols]

 1 Work 2 Sealed Space Forming Section 3 Air Supply Section 4 Pressure Detection Section 5 Capsule 6a, 6b Elastic Ring 7 Pressurizing Section 10 Cylindrical Storage Jig S Sealed Space

Claims (5)

[Claims] 1. An airtight leak detecting section of a cylindrical work having at least one open end is surrounded by a capsule to form a space for sealing the airtight leak detecting section with the inner peripheral surface of the capsule and the outer peripheral surface of the work. An airtightness inspection method, characterized in that the inside of the closed space is vacuum-sucked, high-pressure air is supplied into the work from the opening end, and the pressure in the closed space is detected in that state. 2. The sealed space is formed by interposing a pair of elastic rings between the inner peripheral surface of the capsule and the outer peripheral surface of the work piece across the airtight leak detecting portion, and the elastic ring is formed on the work piece. 2. The airtightness inspection method according to claim 1, wherein the method is performed by pressurizing in an axial direction and expanding in a direction orthogonal to the work axis so as to be in close contact with the capsule inner peripheral surface and the work outer peripheral surface. 3. A closed space forming part that surrounds an airtight leak detection part of a cylindrical work having at least one open end to form a closed space, a vacuum suction source that vacuum-sucks the inside of the closed space, and the work. An airtightness inspection apparatus comprising: an air supply unit for supplying high-pressure air therein; and a pressure detection unit for detecting the pressure in the closed space. 4. The hermetically sealed space forming portion is interposed between the capsule surrounding the airtight leakage detecting portion and the inner peripheral surface of the capsule and the outer peripheral surface of the work piece with the airtight leakage detecting portion sandwiched therebetween. An elastic ring, and a pressurizing portion that pressurizes the elastic ring in the axial direction of the work and pushes the elastic ring in a direction orthogonal to the work axis to bring the capsule inner peripheral surface and the outer peripheral surface of the capsule into close contact with each other. Item 3. The airtightness inspection device according to item 3. 5. A hollow work having a pair of openable and closable holding portions and coaxially joining and integrating a plurality of tubular members to surround the joining portion of a hollow work having at least one opening end, and to the side wall. A cylindrical capsule having a vacuum suction hole formed therein, an elastic ring housed in the holding portion of the capsule, and interposed between the inner peripheral surface of the capsule and the outer peripheral surface of the work piece so as to be spaced apart from each other with the joint portion interposed therebetween, The elastic ring is pressed in the axial direction of the work through the holding part and pushed in the direction orthogonal to the work, and the elastic ring is brought into close contact with the inner peripheral surface of the capsule and the outer peripheral surface of the work to form a sealed space at the joint between both peripheral surfaces. A cylindrical storage jig having a pressurizing section and a through hole for air supply and work storage, which is coaxially arranged in proximity to the capsule with the pressurizing section sandwiching the capsule, and a through hole of the storage jig. Through the open end of the work piece into the hollow An air supply unit that supplies compressed air, a vacuum suction source that communicates with the vacuum suction hole of the capsule to suck the vacuum of the sealed space, and a vacuum suction source that communicates with the vacuum suction hole to detect the pressure of the sealed space of the joint. And a pressure detector for inspecting the airtightness of the joint.