Radiation source assembly and connector press used in producing such assemblies

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates, in general, to a radiation source assembly used in a nondestructive inspection process and a connector press used in producing such assemblies and, more particularly, to an Ir-192 radiation source assembly, with a source capsule having double-sealed radiation source discs and two connectors, or a cap connector and a female connector being respectively coupled to both ends of a pigtail, and to a connector press used for compression-connecting the two connectors to both ends of such a pigtail so as to form a desired radiation source assembly.

2. Description of the Prior Art

In order to produce a radiation source used in a nondestructive inspection, a plurality of Ir-radiation source discs have been conventionally used. Some countries import radiation source disc targets from foreign countries. Such disc targets are primarily processed products, and so they must be pre-processed and finally processed before they are exposed to neutrons within a nuclear reactor. A conventional pre-process and a conventional final process for the disc targets will be described as follows.

Primarily, both diameter and thickness of such a disc target are measured prior to inspecting any external defect of the disc target with the naked eye. Sometimes, such a naked eye inspection may discover a defect on one surface of a disc target.

Thereafter, the flatness of the disc target is measured. Since conventional radiation source disc targets are typically produced through a punching process, the disc targets fail to have a desired flatness. Therefore, it is necessary to flatten the radiation source disc target with a nonmetal hammer while interposing the disc target between two flat metal discs. When the radiation source disc target fails to accomplish a desired flatness, it is almost impossible for the disc target to perform a desired operational performance of a point source or to provide a high quality nondestructive inspection image.

It is also necessary to completely remove micro debris from the surface of the radiation source disc target since such micro debris may cause a radioactive contamination.

After the pre-process, the radiation source disc target is washed using neutral detergent and distilled water, and is finally ultrasonically washed prior to being dried, thus completely preparing a desired radiation source disc target. The dimension of the disc target is measured and is compared with calculated values. The prepared disc target is an Ir-metal type disc having a diameter of 2.5 mm, a thickness of 0.25 mm, a weight of 27.6 mg/disc, a nuclidic purity of 99.9%, and a specific weight of 22.5 g/cm

3

.

After preparing the radiation source disc targets and manufacturing a radiation source capsule, a desired radiation source is produced. In order to produce a desired radiation source, a plurality of disc targets, enclosed within an aluminum irradiation container, are exposed to neutrons within a neutron irradiation hole of a multi-purpose nuclear reactor for a predetermined period of time. After the neutron irradiation process, the irradiation container is removed from the neutron irradiation hole of the nuclear reactor and is received within a carrier vessel, and is moved to a concrete hot cell along with the vessel. Within the concrete hot cell, the irradiation container is removed from the carrier vessel by a manipulator. The irradiation container is, thereafter, set in automatic classifying and measuring equipment. When a control unit of the equipment is turned on, the container is automatically processed through a container cutting process, a radioactivity measuring process, and a classified radiation source capsuling process in accordance with a program of the control unit. In such a case, the Ir-disc targets from the radioactivity measuring process are received within a stainless capsule in a way such that 5 to 10 disc targets are received within each capsule. The stainless capsule is, thereafter, closed by a lid prior to being welded into a single structure at the junction between the capsule and the lid through a plasma arc welding process, thus forming a sealed radiation source.

When such a radiation source capsule is completely produced, a desired radiation source assembly is produced. An example of conventional radiation source assemblies is shown in the accompanying drawing, FIG.

1

.

As shown in the drawing, the radiation source assembly

1

comprises a source capsule

3

, a female connector

5

and a pigtail

7

. In such a case, the source capsule

3

is made of SUS 316L, and consists of a cap connector

9

, an outside cap

11

and an inside capsule

13

. As best seen in

FIG. 2

, the cap connector

9

receives one end of the pigtail

7

, while the outside cap

11

is welded to the cap connector

9

through a TIG welding process. The inside capsule

13

is set within the outside cap

11

.

In order to receive the inside capsule

13

, the outside cap

11

has a cavity. The above cap

11

also has an arcuate cross-section, with the tip of the cap

11

being rounded. The object of such a rounded tip of the cap

11

is to minimize a kinetic resistance generated at the tip when the radiation source assembly passes through guide tube of a nondestructive inspection apparatus. The inside cap

11

is fitted over a connecting projection

31

of the cap connector

9

at its fitting opening prior to being integrated with the connector

9

into a single structure through a TIG welding process.

The cap connector

9

, connected to the pigtail

7

, is a cylindrical member provided with a pigtail fitting hole

15

. The connecting projection

31

is provided on an end of the cap connector

9

opposite to the pigtail fitting hole

15

.

As shown in

FIG. 3

, the inside capsule

13

, set within the outside cap

11

, consists of a cylindrical outside case

14

, a sealing cover

16

and a filler

17

. The outside case

14

receives a plurality of radiation source disc targets

10

in a way such that the targets

10

are regularly stacked. The sealing cover

16

is fitted into the top open end of the outside case

14

, thus sealing the outside case

14

. The filler

17

is interposed between the sealing cover

16

and the stacked targets

10

so as to press the targets

10

.

As best seen in

FIGS. 4

a

and

4

b

, the pigtail

7

consists of a wire core

23

, a primary coil

25

, a secondary coil

27

, and a large-diameter coil

29

. The wire core

23

is made by twisting a plurality of wires

21

, the primary coil

25

is wound around the wire core

23

. The secondary coil

27

is wound around the primary coil

25

. The large-diameter coil

29

, having a predetermined regular pitch, is wound around the primary coil

25

along with the secondary coil

27

. In such a case, all the wires and coils of the pigtail

7

are made of carbon steel, and so they have a predetermined elasticity. The wires and coils of the pigtail

7

are not undesirably wear-cut or loosened even though the pigtail

7

is used ten thousand or more times. The wires and coils are also free from corrosion even when they are exposed to atmospheric air.

The above radiation source assembly

1

passes through a guide tube under the control of a manipulation handle connected to a male connector engaging with the female connector

5

of the assembly

1

. The assembly

1

is thus finally received within a radiation source carrier. Such an assembly

1

enclosed by the radiation source carrier is used with a nondestructive inspection apparatus. During a nondestructive inspecting operation, the assembly

1

reaches an inspection point by the guide tube. When the radiation source assembly

1

is kept within the radiation source carrier, a stop ball

19

, formed on one end of the female connector

5

positioned at the rear end of the assembly

1

as shown in

FIG. 5

, is locked to an inside wall of the carrier, thus being firmly and precisely positioned within the carrier. This finally completely prevents a radiation leakage, caused by an assembly

1

failing to be precisely positioned within the carrier.

In the conventional radiation source assembly

1

, the source capsule

3

and the female connector

5

are locked to both ends of the pigtail

7

through a compressing process. That is, as shown in

FIGS. 2 and 5

, both ends of the pigtail

7

are primarily fitted into the first pigtail fitting hole

15

of the cap connector

9

of the source capsule

3

and the second pigtail fitting hole

18

of the female connector

5

, respectively. Thereafter, the female connector

5

and the cap connector

9

are inwardly compressed in a radial direction using a dedicated connector press until the two connectors

5

and

9

are locked to both ends of the pigtail

7

. However, the conventional radiation source assembly

1

is problematic in that the two connectors

5

and

9

may be unexpectedly removed from both ends of the pigtail

7

during an operation of the assembly

1

.

In addition, when the two connectors

5

and

9

are fitted over both ends of the pigtail

7

, the ends of the pigtail

7

may fail to completely reach the inside ends of the fitting holes

15

and

18

of the two connectors

9

and

5

in accordance with the linearity of the pigtail

7

, the flatness and linearity of the fitting holes

15

and

18

of the two connectors

9

and

5

, and/or the pressure applied to the source capsule

3

and the female connector

5

while fitting the capsule

3

and female connector

5

over both ends of the pigtail

7

. It is thus almost impossible to assure desired positions of both ends of the pigtail

7

within the two connectors

5

and

9

prior to compressing the two connectors

5

and

9

over the pigtail

7

. Furthermore, the inserted lengths of the pigtail

7

within the two connectors

5

and

9

are not sufficient to provide a desired linearity of the assembly

1

after the connectors

5

and

9

are compression-locked to both ends of the pigtail

7

.

In the above radiation source assembly

1

, the outside case

14

of the inside capsule

13

is closed by and welded to a sealing cover

16

while accomplishing a desired sealing effect, with the disc targets

10

and the filler

17

being set within the outside case

14

. When the number and/or thickness of the stacked disc targets

10

does not agree with the length of the filler

17

, the disc targets

10

may slip on each other or may be separated from each other within the outside case

14

. In such a case, the disc targets

10

, or the point sources of a radiography, may be movable during a nondestructive inspecting operation of the assembly

1

, thus failing to provide a clear image and to provide precise nondestructive inspecting results.

On the other hand, the cap connector

9

of the source capsule

3

is welded to the pigtail

7

through a TIG welding process. However, the materials of both the capsule

3

and the pigtail

7

may be undesirably changed in their physical characteristics due to heat generated during the TIG welding process, thus causing a thermal defect and a thermal deterioration at the welded junction between the cap connector

9

and the pigtail

7

. In an effort to overcome such a thermal defect and such a thermal deterioration at the welded junction between the cap connector

9

and the pigtail

7

, the cap connector

9

may be locked to the pigtail

7

through a compression process rather than the welding process.

As shown in

FIG. 6

, such a compression process of locking the cap connector

9

to the pigtail

7

uses a dedicated connector press

51

. The conventional connector press

51

compresses the cap connector

9

of the source capsule

3

with the pigtail

7

being fitted into the cap connector

9

, thus locking the capsule

3

to the pigtail

7

and making a desired radiation source assembly. In such a case, the target portion to be compressed is the overlapped portion of the cap connector

9

engaging with the pigtail

7

.

When the cap connector

9

of the capsule

3

is compression-locked to the pigtail

7

using the press

51

consisting of top and bottom dies

53

and

55

as shown in

FIG. 6

, there is a deviation of the compression force in an axial direction of the pigtail

7

, with the compression force being applied to the overlapped portion of the cap connector

9

engaging with the pigtail

7

, even though the compression force is uniformly distributed on the overlapped portion in a vertical direction. Therefore, it is almost impossible for a resulting assembly

1

to have a desired linearity.

The radiation source assembly

1

failing to have such a desired linearity does not accomplish required conditions of assemblies. Such an assembly

1

may be also excessively abraded when it repeatedly moves within the guide tube in opposite directions, and so the assembly

1

, having a dangerous radioactive material, may fail to accomplish a desired degree of operational safety and may cause a radioactive contamination.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a radiation source assembly, of which each of the cap connector and the female connector is provided with internal round threads on its pigtail fitting hole, thus engaging with the large-diameter coil of the pigtail at the internal round threads through a thread engagement prior to a compression process and being almost completely prevented from an unexpected removal from the pigtail, which allows a person to know whether both ends of the pigtail fully reach desired points within the two connectors, thus securing a precise compressing target portion, and of which the inserted lengths of the pigtail relative to the two connectors are maximized, thus accomplishing a desired linearity of the assembly.

Another object of the present invention is to provide a radiation source assembly, which is provided with a target biasing spring on the capsule lid for allowing the disc targets within the source capsule to effectively maintain a desired condition as point sources regardless of the number of targets, with a capsule lid biasing device being provided on a dedicated welding jig for allowing the capsule lid to be welded to a capsule body while maintaining the disc targets in the states of point sources and improving the weldability of an inside capsule of the source capsule.

A further object of the present invention is to provide a connector press used in producing the radiation source assemblies, which accomplishes a desired compression locking of the source capsule to the elastic pigtail by simultaneously compressing the capsule at regularly and angularly spaced points through a multi-point compressing process, and which thus accomplishes a desired linearity of the capsule and the pigtail, and prevents the capsule from causing an operational error or being abrasion-damaged due to a frictional resistance generated at the capsule when the capsule repeatedly moves within a guide tube in opposite directions.

The above-mentioned primary object of this invention is accomplished by a radiation source assembly, comprising a source capsule enclosing a radiation source, a female connector connected to a male connector coupled to a manipulation handle, and a pigtail connecting the source capsule and the female connector together, wherein a cap connector of the source capsule has first internal threads on its pigtail fitting hole, with the first internal threads having a profile corresponding to a large-diameter coil of the pigtail and engaging with the large-diameter coil of a first end of the pigtail through a thread engagement.

In the above assembly, the female connector has second internal threads on its pigtail fitting hole, with the second internal threads having a profile corresponding to the large-diameter coil of the pigtail and engaging with the large-diameter coil of a second end of the pigtail through a thread engagement. The number of each of the first and second internal threads is four or more.

The above-mentioned second object of the present invention is accomplished by a radiation source assembly, comprising: a capsule body receiving stacked radiation source disc targets; a capsule lid fitted into an open end of the capsule body and welded to the capsule body, thus sealing the capsule body; and a coil spring set within a spring seat hole of the capsule lid and adapted to normally bias the radiation source disc targets within the capsule body in a direction after the capsule lid is welded to the capsule body.

The above-mentioned third object of the present invention is accomplished by a connector press for producing a radiation source assembly by compression-locking a source capsule to a first end of a pigtail of the assembly, with the source capsule being fitted over the first end of the pigtail prior to a compression-locking process of the press, comprising: a plurality of compression punches radially arranged on a holding disc at regularly and angularly spaced positions to compress an overlapped portion of the source capsule fitted over the pigtail at regularly and angularly spaced external points; a plurality of pressure rods hinged to an edge of a support at regularly and angularly spaced positions and adapted to respectively and inwardly push the compression punches in a radial direction of the holding disc at outside ends of the punches; and a reciprocable push rod being movable in opposite directions in cooperation with a cylinder actuator so as to synchronously rotate the pressure rods around hinge points of the pressure rods, thus allowing the pressure rods to be opened or closed at their punch pushing ends and to selectively push the compression punches inwardly in the radial direction of the holding disc.

In the above connector press, each of the compression punches is movably received within a radial guide member of the holding disc, thus being radially reciprocable on the holding disc under the guide of the guide member, with a compression tip having a radius of curvature equal to a desired compressed radius of the source capsule and being removably attached to an inside end of each compression punch, and a return spring connecting each of the compression punches to the holding disc so as to elastically return each compression punch to its original position within the guide member when an external force is removed from each compression punch.

In addition, each of the pressure rods is provided with a roller at an end opposite to its punch pushing end. On the other hand, the push rod is provided with a truncated conical push block at an outside end thereof, the push block having an inclined surface due to its truncated conical shape, with rollers of the pressure rods being brought into rotatable contact with the inclined surface of the push block, thus allowing the pressure rods to be synchronously closed at their punch pushing ends when the push rod is moved toward the support of the pressure rods by a driving force of the cylinder actuator.

The above connector press further comprises: a scale rod movably inserted at a center of the support and adapted for supporting a tip of the source capsule; and an adjusting screw radially and movably threaded into the support from the outside to the center of the support and adapted for holding or releasing the scale rod within the center of the support.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1

is a front view of a conventional radiation source assembly;

FIG. 2

is a sectional view, showing the construction of a source capsule connected to one end of a pigtail of the conventional assembly shown in

FIG. 1

;

FIG. 3

is a sectional view, showing the construction of an inside capsule of the source capsule shown in

FIG. 2

;

FIGS. 4

a

and

4

b

are views of the pigtail included in the conventional assembly of

FIGS. 1 and 2

, in which

FIG. 4

a

is a front view showing the profile of the pigtail, and

FIG. 4

b

is a sectional view of the diameters of core and coils of the pigtail;

FIG. 5

is a sectional view, showing the construction of a female connector connected to the other end of the pigtail of the conventional assembly shown in

FIG. 1

;

FIG. 6

is a front view, schematically showing the construction of a conventional press used for compression-locking the cap connector of the source capsule to the pigtail of the assembly of

FIG. 2

;

FIG. 7

is a front view of a radiation source assembly in accordance with the preferred embodiment of the present invention;

FIG. 8

is an exploded sectional view, showing the construction of a source capsule included in the assembly of

FIG. 7

;

FIG. 9

is an exploded sectional view, showing the construction of an inside capsule of the source capsule shown in

FIG. 7

;

FIG. 10

is a front view, showing the construction of a connector press used for producing the assembly of this invention;

FIG. 11

is a front view of a triple-point compression punch unit included in the press of

FIG. 10

;

FIG. 12

is a front view of a support included in the press of

FIG. 10

;

FIG. 13

is a side view, showing a compression punch of the press of

FIG. 10 and a

source capsule of a radiation source assembly to be compression-locked to a pigtail by the compression punch; and

FIG. 14

is a plan view of a pressure rod included in the press of FIG.

10

.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 7

is a front view of a radiation source assembly in accordance with the preferred embodiment of the present invention. As shown in the drawing, the radiation source assembly

101

comprises a pigtail

107

, with a source capsule

103

and a female connector

105

respectively connected to both ends of the pigtail

107

.

In the assembly

101

of this invention, the pigtail

107

has the same construction as that of the conventional pigtail

7

of

FIGS. 4

a

and

4

b

. That is, the pigtail

107

is an elastic rod having a round thread profile and consisting of a wire core made by twisting a plurality of carbon steel wires. A primary coil is wound around the wire core, while a secondary coil

127

is wound around the primary coil. A large-diameter coil

129

, having a predetermined regular pitch, is wound around the primary coil along with the secondary coil

127

. The above pigtail

107

is made of carbon steel, and so the pigtail

107

is not undesirably wear-cut or loosened even though it is used a great number of times in the same manner as that described for the conventional pigtail

7

. The pigtail

107

is also free from corrosion even when its is exposed to atmospheric air.

On the other hand, the source capsule

103

, connected to a first end of the pigtail

107

, consists of a cap connector

109

, an outside cap

111

and an inside capsule

113

. The cap connector

109

, connected to the pigtail

107

, is a cylindrical member provided with a pigtail fitting hole

115

for receiving the first end of the pigtail

107

. A connecting projection

131

is provided on an end of the cap connector

109

opposite to the pigtail fitting hole

115

, with the outside cap

111

being fitted over the connecting projection

131

at its fitting opening.

In the assembly

101

of this invention, the pigtail

107

has a round thread profile as described above, with the large-diameter coil

129

forming screw threads. In order to allow the cap connector

109

of the source capsule

103

to engage with the first end of the pigtail

107

through a thread engagement, the connector

109

has internal round threads

119

on the pigtail fitting hole

115

, with the threads

119

having a profile corresponding to the large-diameter coil

129

of the pigtail

107

. In the preferred embodiment of

FIG. 8

, four internal round threads

119

are formed on the inside wall of the pigtail fitting hole

115

of the cap connector

109

, thus engaging with four screw threads of the large-diameter coil

129

of the pigtail

107

. In the preferred embodiment, the number of internal round threads

119

formed on the pigtail fitting hole

115

, or four, is determined as an example since the four threads

119

are the minimum number of threads which can accomplish a desired linearity of the pigtail

107

with the cap connector

109

compression-locked to the pigtail

107

. Therefore, it should be understood that four or more internal round threads

119

may be formed on the inside wall of the cap connector

109

without affecting the functioning of this invention if the number of threads

119

is not restricted by a variety of nuclear equipment standards.

In order to receive the inside capsule

113

, the outside cap

111

has a cavity. The inside cap

111

also has an arcuate cross-section, with the tip of the cap

111

being rounded. The object of such a rounded tip of the cap

111

is to minimize a kinetic resistance generated at the tip when the radiation source assembly

101

passes through the guide tube of a nondestructive inspection apparatus. The inside cap

111

is fitted over the connecting projection

131

of the cap connector

109

at its fitting opening prior to being integrated with the connector

109

into a single structure through a TIG welding process.

In such a case, the inside capsule

113

is made of SUS 316L, and has a side length of at least 0.5 cm in order to meet the requirement disclosed in the enforcement regulations of atomic energy law. As shown in

FIG. 9

, the inside capsule

113

, set within the outside cap

111

, consists of a cylindrical capsule body

117

receiving stacked disc targets

116

. A capsule lid

126

is fitted into the open end of the capsule body

117

prior to being welded to the body

117

, thus sealing the capsule body

117

. A coil spring

123

is set within a spring seat hole

121

of the capsule lid

126

and normally biases the disc targets

116

in a direction when the capsule lid

126

is integrated with the capsule body

117

through a welding process.

The above capsule body

117

is a hollow cylindrical body, which receives the disc targets

116

therein and is open at one end thereof so as to engage with the capsule lid

126

at the open end. The capsule body

117

has an outer diameter, which allows the body

117

to be closely fitted into the outside cap

111

, and has an inner diameter which is slightly larger than the diameter of the disc targets

116

so as to allow the targets

116

to be movable within the capsule body

117

. The capsule lid

126

, closing the capsule body

117

, is a cylindrical member having an outer diameter slightly smaller than the inner diameter of the capsule body

117

. The capsule lid

126

also has a flange

125

at its outside end, with the spring seat hole

121

for the target biasing spring

123

being concentrically formed at the inside end of the lid

126

. Prior to a welding process of integrating the capsule lid

126

with the capsule body

117

, the capsule lid

126

is fully fitted into the open end of the capsule body

117

with the flange

125

coming into close contact with the edge of the open end of the capsule body

117

.

When the capsule lid

126

is welded to the capsule body

117

, a dedicated welding jig is used. In order to weld the capsule lid

126

to the capsule body

117

, a plurality of stacked disc targets

116

are set within the capsule body

117

prior to firmly holding the capsule body

117

to the welding jig. After the capsule body

117

is held on the welding jig, the capsule lid

126

, with the target biasing spring

123

, is fully fitted into the open end of the body

117

prior to integrating the capsule lid

126

with the capsule body

117

into a single structure at the junction between the flange

125

of the lid

126

and the edge of the open end of the capsule body

117

through a plasma welding process or a TIG welding process. Therefore, it is possible to stably set the disc targets

116

in the form of point sources within the capsule body

117

while elastically holding the targets

116

by the spring

123

and preventing an undesirable movement of the targets

116

within the capsule body

117

.

When the cap connector

109

of the source capsule

103

is connected to the first end of the pigtail

107

so as to make a desired radiation source assembly

101

of this invention, the first end of the pigtail

107

engages with the cap connector

109

through a thread engagement. In such a case, the internal round threads

119

formed on the inside wall of the pigtail fitting hole

115

of the cap connector

109

act as a guide passage for the large-diameter coil

129

of the pigtail

107

.

After the cap connector

109

engages with the first end of the pigtail

107

through a thread engagement, the cap connector

109

is compressed at its external surface by the connector press of this invention, thus being compression-locked to the first end of the pigtail

107

.

In the same manner as that described for the cap connector

109

, the second end of the pigtail

107

primarily engages with the female connector

105

through a thread engagement in order to connect the female connector

105

to the second end of the pigtail

107

. In such a case, the internal round threads

120

formed on the inside wall of the pigtail fitting hole

114

of the female connector

105

act as a guide passage for the large-diameter coil

129

of the pigtail

107

. After the female connector

105

engages with the second end of the pigtail

107

, the female connector

105

is compressed at its external surface by the connector press of this invention, thus being compression-locked to the second end of the pigtail

107

.

In the radiation source assembly

101

of this invention, the disc targets

116

are stably set within the capsule body

117

while being elastically held by the spring

123

of the capsule lid

126

and being prevented from an undesirable movement within the capsule body

117

. The disc targets

116

thus maintain desired states of point sources regardless of the number of targets

116

during a nondestructive inspecting operation, and so it is possible for the targets

116

to provide a high quality nondestructive inspection image with a precise focusing on an object.

In addition, a device for biasing the capsule lid

126

is provided on the dedicated welding jig for allowing the capsule lid

126

to be welded to the capsule body

117

while maintaining the disc targets

116

in the states of point sources. It is thus possible to improve the weldability of the inside capsule

113

.

FIGS. 10

to

12

show the construction of a connector press

201

used for producing the radiation source assemblies

101

of this invention. As shown in the drawings, the connector press

201

accomplishes a desired compression locking of the source capsule

103

, enclosing the radiation source disc targets

116

, to the elastic pigtail

107

by simultaneously compressing the capsule

103

at regularly and angularly spaced points through a multi-point compressing process, thus producing a desired radiation source assembly

101

. In the preferred embodiment shown in the drawings, the connector press

201

is a triple-point press as an example.

The connector press

201

comprises a base

210

, with a plurality of compression punches

209

, a drive cylinder actuator

221

, a push rod

219

and a plurality of pressure rods

213

being installed on the base

210

. In the connector press

201

, the compression punches

209

compress the source capsule

103

against the pigtail

107

of the assembly

101

. The drive cylinder actuator

221

generates a drive force which is supplied to the compression punches

209

. The one push rod

219

and the several pressure rods

213

transmit the drive force of the actuator

221

to the compression punches

209

while converting the horizontal force of the actuator

221

into a vertical force for the punches

209

.

The compression punches

209

are designed to compress the overlapped portion of the source capsule

103

fitted over the pigtail

107

at regularly and angularly spaced external points. In the embodiment of

FIG. 11

, three compression punches

209

are radially held on a punch holding disc

225

at regularly and angularly spaced positions, thus forming a triple-point compression punch unit. That is, the three compression punches

209

are regularly and radially positioned on the holding disc

225

while being spaced out at angular intervals of 120°. The punch holding disc

225

is fixed to a support

211

using a plurality of set bolts

241

, with the support

211

being mounted on the base

210

of the press

201

.

The three compression punches

209

are movably received within three radial guide channels of a guide member

223

in a way such that the punches

209

are radially reciprocable on the holding disc

225

under the guide of the guide channels. The above guide member

223

is mounted to the holding disc

225

using a plurality of set bolts

243

with the guide channels radially positioned on the disc

225

. A compression tip

227

, with a compression blade

228

, is provided on the inside end of each compression punch

209

. In such a case, the compression tip

227

is removably attached to the inside end of each punch

209

, and so it is possible to selectively attach a compression tip

227

, having a radius of curvature equal to the desired compressed radius of a source capsule

103

, to the inside end of each punch

209

. A transverse member

234

is fixed to each of the guide channels of the guide member

223

while passing across each guide channel at an upper position while being free from interfering with a radial movement of an associated compression punch

209

. Each of the transverse members

234

is connected to an associated compression punch

209

by an extension coil spring

229

, or a return spring, and so the punches

209

are automatically returned to their outside positions within the guide channels of the guide member

223

due to the restoring force of the return springs

229

when the external force is removed from the punches

209

.

As shown in

FIG. 12

, the support

211

, holding the punch holding disc

225

, is a flat plate chamfered at its corners. A plurality of bolt holes

245

for the set bolts

241

are formed on the support

211

at regularly and angularly spaced positions on one circle. In order to rotatably hold the three pressure rods

213

for the three compression punches

209

, the support

211

has three notches

247

on its outside edge at regularly spaced positions of an angular interval of 120°. A through hole

249

is perpendicularly formed on each of the notches

247

, thus receiving a holding pin

251

rotatably holding an associated pressure rod

213

on the disc

225

.

A central hole

224

is formed at the center of the support

211

and receives a scale rod

226

which supports the outside end of the source capsule

103

of a radiation source assembly

101

, the assembly

101

being held by the inside ends of the three compression punches

209

. In order to hold the scale rod

226

at a desired position within the support

211

, an adjusting screw

232

, used for adjusting a compressing target position, is radially inserted from one chamfered top corner into the center of the support

211

. A knob

236

is mounted to the outside end of the adjusting screw

232

, while the body of the rod

232

is externally threaded. Therefore, the radial position of the adjusting screw

232

relative to the support

211

is adjustable by rotating the knob

236

at the outside of the support

211

, thus fixing or releasing the scale rod

226

within the support

211

as desired. As shown in

FIG. 10

, a graduation is formed on the external surface of the scale rod

226

, thus allowing a person to see the inserted length of the assembly

101

at the outside of the press

201

.

As shown in

FIG. 10

, the three pressure rods

213

, inwardly pushing the compression punches

209

in a radial direction at the outside ends of the punches

209

, are rotatably mounted to the notches

247

of the support

211

at their hinge points

217

. The hinge point

217

of each pressure rod

213

is positioned at about ⅓ of the total length from the front end, or the punch pushing end of the pressure rod

213

. The rear end of each pressure rod

213

is provided with a roller

231

. The above roller

231

is set within a roller seat slit

255

formed on the rear end of the pressure rod

213

and is rotatably held within the slit

255

by a pin

253

as shown in

FIGS. 10 and 14

.

A push block

235

, coming into contact with the rollers

231

of the pressure rods

213

, is a truncated conical member, with an inclined surface

233

at which the rollers

231

commonly come into movable contact with the block

235

. The above push block

235

is axially moved by the drive force of the actuator

221

, thus rotating the pressure rods

213

around the holding pins

251

mounted at the hinge points

217

of the pressure rods

213

. The pressure rods

213

are thus opened or closed at their punch pushing ends. The push block

235

is connected to the actuator

221

through the push rod

219

.

The reciprocable push rod

219

is mounted to the cylinder actuator

221

and axially reciprocates by the drive force of the actuator

221

, thus allowing the rollers

231

of the pressure rods

213

to be moved along the inclined surface

233

of the push block

235

. The cylinder actuator

221

is horizontally installed on the base

210

by a support frame

257

.

The operational effect of the above connector press

201

while producing a radiation source assembly

101

will be described hereinbelow.

Prior to a compression-locking process performed by the press

201

, a source capsule

103

, with a plurality of radiation source disc targets

116

, engages with the first end of a pigtail

107

. In such a case, the first end of the pigtail

107

may engage with the capsule

103

through a forcible fitting process or through a thread engagement in accordance with the kind of a desired assembly

101

.

After the source capsule

103

primarily engages with the first end of the pigtail

107

, the assembly

101

is carefully positioned within the connector press

201

in a way such that the overlapped portion of the capsule

103

engaging with the pigtail

107

is precisely positioned within the center of the radially arranged compression punches

209

as shown in FIG.

10

. The position of the assembly

101

relative to the three compression punches

209

is best seen in FIG.

13

. When the position of the assembly

101

relative to the punches

209

is set, the adjusting screw

232

is loosened prior to carefully moving the scale rod

226

to the left or right until the position of the scale rod

226

is completely adjusted to accomplish a desired depth corresponding to the determined compressing target position. Thereafter, the adjusting screw

232

is tightened, thus fixing the adjusted position of the scale rod

226

. When the adjusted position of the scale rod

226

is fixed as described above, it is possible to precisely set the compressing target position of the source capsule

103

which is to be compressed by the compression blades

228

of the tips

227

of the three punches

209

.

When the radiation source assembly

101

is completely set within the press

201

, the cylinder actuator

221

is turned on, thus axially moving the push rod

219

along with the push block

235

toward the support

211

. Due to such a movement of the push block

235

toward the support

211

, the rollers

231

of the pressure rods

213

simultaneously roll up along the inclined surface

233

of the truncated conical push block

235

.

When the rollers

231

of the pressure rods

213

roll upwardly along the inclined surface

233

of the push block

235

, the three pressure rods

213

are rotated clockwise around the hinge points

217

in FIG.

10

. Therefore, each of the three pressure rods

213

inwardly biases an associated one of the three compression punches

209

in a radial direction of the holding disc

225

with a force stronger than that applied to the roller

231

three times due to a leverage effect.

In such a case, the three compression punches

209

move radially and inwardly at the same time under the guide of the guide channels of the guide member

223

shown in FIG.

11

, thus synchronously compressing the target portion of the source capsule

103

by their compression blades

228

at three points.

After the compression locking process performed by the three punches

209

, the push rod

219

moves toward the cylinder actuator

221

, thus returning to its original position. In such a case, the push block

235

,also returns to its original position while allowing the rollers

231

of the pressure rods

213

to roll down along the inclined surface

233

of the push block

235

. Therefore, the pressure rods

213

are rotated counterclockwise around the hinge points

217

in

FIG. 10

, thus removing the biasing force from the three compression punches

209

. Therefore, the compression punches

209

automatically move outwardly in the radial direction by the restoring force of the return springs

229

, thereby allowing the assembly

101

to be removed from the press

201

.

As described above, the present invention provides a radiation source assembly. In the assembly, the cap connector of a radiation source capsule and the female connector engaging with the male connector of a manipulation handle are each provided with internal round threads on its pigtail fitting hole. Each of the two connectors thus engages with the large-diameter coil of the pigtail at the internal round threads through a thread engagement prior to being compressed at a target portion by a plurality of compression punches of a connector press. Therefore, the two connectors, which are threaded with and compression-locked to both ends of the pigtail, are almost completely prevented from an unexpected removal from the pigtail different from a conventional assembly wherein the two connectors engage with the pigtail through a forcible fitting engagement prior to being compression-locked to the pigtail. In addition, the radiation source assembly of this invention allows a person to know whether both ends of the pigtail fully reach desired points within the two connectors, thus securing a precise compressing target portion. In the assembly of this invention, the inserted lengths of the pigtail relative to the two connectors are maximized, thus accomplishing a desired linearity of the assembly. Therefore, it is thus possible for a user to precisely, appropriately and safely use the radiation source assembly of this invention during a nondestructive inspecting operation. In addition, the assembly of this invention effectively minimizes the frictional resistance generated at the source capsule when the capsule repeatedly moves within a guide tube in opposite directions. The assembly is thus almost completely free from an operational error or being abrasion-damaged, or an unexpected radioactive contamination.

The present invention also secures a uniform length of the radiation source assemblies, thus allowing the assemblies to be precisely and firmly installed at desired positions within nondestructive inspecting apparatuses or within dedicated carriers. This finally and effectively reduces a radiation leakage from the assembly.

In the radiation source assembly of this invention, a target biasing spring is provided on the capsule lid for allowing the disc targets within the inside capsule of the source capsule to effectively maintain a desired condition as point sources regardless of the number of targets, with the capsule lid being fitted into and welded to a capsule body of the inside capsule. Therefore, the assembly of this invention provides a high quality nondestructive inspection image with a precise focusing on an object. In addition, a capsule lid biasing device is provided on a dedicated welding jig of this invention for allowing the capsule lid to be welded to the capsule body of the inside capsule while being biased by the device. Therefore, it is possible to prevent inert gas from being undesirably introduced into the inside capsule through the junction between the capsule body and the capsule lid during a TIG welding process performed in an inert gas atmosphere. This finally accomplishes a welding process for the inside capsule of the source capsule while maintaining the disc targets in the states of point sources and improves the weldability of the source capsule.

The present invention also provides a connector press used in producing the radiation source assemblies. The connector press of this invention accomplishes a desired compression locking of the source capsule to the elastic pigtail by simultaneously compressing the capsule at regularly and angularly spaced points through a multi-point compressing process. The connector press of this invention thus applies a uniform compressing force to the compressing target portion of the capsule engaging with the pigtail, and so the press accomplishes a desired linearity of the capsule and the pigtail.

Therefore, when the assembly of this invention is used in a nondestructive inspecting operation with the source capsule repeatedly moving within a radiation shield guide tube in opposite directions, the assembly is free from being exceedingly bent at the compression-locked portion. This finally prevents the assembly from causing an operational error or being abrasion-damaged due to a frictional resistance generated at such a bent portion, thus accomplishing a desired operational safety of the assembly.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Number	Date	Country
UM 1999-16981	Aug 1999	KR
P 1999-33982	Aug 1999	KR
P1999-33983	Aug 1999	KR

Number	Name	Date	Kind
4827493	Parsons et al.	May 1989	A
5418379	Parsons et al.	May 1995	A

Radiation source assembly and connector press used in producing such assemblies

Information

Patent Number

Date Filed

Date Issued

Inventors

Original Assignees

Examiners

Agents

CPC

US Classifications

Field of Search

US

International Classifications

Term Extension

Abstract

Description

Claims

Priority Claims (3)

US Referenced Citations (2)