World's fifth beryllium smeltery built in NW. China

The earthwork of a beryllium smeltery, believed to be the fifth of its kind in the world, has been completed in Fuyun County in northern Xinjiang Uygur Autonomous Region, northwest China.

Workers are busy installing and testing equipment at the 50-million-yuan (6-million-US dollars) smeltery and operation is scheduled to begin in November. The annual production of the plant is designed at 100 tons of beryllium oxide and 800 tons of beryllium-copper alloy.

Beryllium, also known as metallic glass, is a deoxidizer and additive applicable for producing many kinds of alloys. It is widely used in the fields of electronics, power, petroleum and chemistry. The beryllium reserve in Fuyun County makes up 70 percent of the total reserve in China. Some 31,300 tons of beryllium ore has been exploited in one mine alone. – Xinhua



We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

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Sam Xu
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China's second beryllium refinery begins operation

China's second beryllium refinery, which is also the world's fifth such refinery, was put into production in Fuyun County in northwest Xinjiang Uygur Autonomous Region earlier this month.

Involving a total investment of 50 million yuan (US$6 million), the new refinery is designed to produce 100 tons of industrial beryllium oxide and 1,000 tons of beryllium-copper mother alloy a year.

The refinery has been constructed by the Fuyun Hengsheng Beryllium Industry Co., Ltd., a joint venture launched by Xinjiang Nonferrous Metals Industry Group, Xinjiang Henghe Investment Co., Ltd. and Xinjiang Nonferrous Metals Industry Group Nonferrous Metals Co.

Fuyun County possesses more than 70 per cent of China's verified beryllium ore reserves.

So far, 3.13 million tons of beryllium ores have been mined from its Keketuohai No.3 mine.

Beryllium, nicknamed metallic glass, is a kind of deoxidant and additive for various alloys.

It is widely applicable to electronic, power, petroleum and chemical industries




We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

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Sam Xu
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Beryllium Copper Finger Strips and Industrial Enclosure Shielding

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Exploring the world of rare earth metals

More common metals such as gold, silver, iron, zinc, lead and copper are well-documented in financial pages such as this, and for good reason. But let’s focus for a moment or so on the lesser-known rare earth metals, those materials with many applications in our daily lives, investing in whose makers can boost the portfolios of those with an eye for value.

Molybdenum is a transition metal that does not react with oxygen or water at room temperature. The ability of molybdenum to withstand extreme temperatures without significantly expanding or softening make it useful in applications that involve intense heat, such as aircraft parts, electrical contacts, industrial motors, and filaments.

One company hard at finding and developing molybdenum is British Columbia-based United Bolero Development Corp., which trades on the TSX Venture under the symbol UNB. Besides its mining enterprises, United had also been busy in the oil patch, but scaled back those activities by the end of 2005, to focus almost exclusively on being a junior mineral exploration company.

UNB currently has options to purchase 100% interests in two properties in southwestern Montana. One of them, the Bald Butte property, has 22 patented claims comprising about 350 acres. Mining there began in June of this year. The deposit at Bald Butte shows an inferred resource of 105 million tons at a high grade of molybdenum.

Another property, elsewhere in the state, has been subject to previous explorations by other companies that have proven rich in molybdenite property.

The burgeoning market for molybdenum should be good news for those looking to snap up potentially strong stocks at low prices. UNB fortunes tailed off a bit from its 52-week peak over the 90-cent Canadian mark during May. At the beginning of August, the stock sat around 60 cents. While out of its 20-cent gully from this time last year, UNB is still very affordable.

Rare earth metals such as lithium are in higher demand, due to the exploding market for hybrid cars. Neodynium is also enjoying a surge for its place in the hybrid car market. Lithium ion is a key component in rechargeable batteries while neodymium is used to make the super magnets integral to hybrid and electric car technology.

All this is good news for such rare earth metal producers as Toronto-based Avalon Ventures Ltd.. Avalon, whose shares trade on the TSX Venture under the symbol AVL, focuses on metals in increasing demand in high technology and environment-friendly applications, including lithium and neodymium, as well as calcium feldspar and beryllium, the latter of which can be used in copper alloys found in electronic products.

Avalon owns five rare metals and mineral projects in Canada, three of them in advanced development. Its Separation Rapids project in northwestern Ontario is hard at work producing lithium, while the Warren Township property, in northeastern Ontario, specializes in calcium feldspar. Its Thor Lake beryllium project, in the Northwest Territories, is home to a high-grade beryllium silicate mineral.

AVL enjoyed a leap in net revenues in fiscal year 2006 to $87,588 Canadian from $414 the year before. Total assets experienced a 50%-plus hike to $6.9 million. AVL stock prices have achieved a five-year peak of $2.21 Canadian in July, after plumbing to a 52-week low of 70 cents Canadian last fall.

Tungsten, though not widely known, is prized for a hardness ranking behind only diamonds, world-leading heat resistance density (greater than lead or uranium) and environmentally-friendly qualities; it neither breaks down nor decomposes.

Tungsten is found in sporting goods (most notably golf clubs and sports fishing weights), jet turbine engines, light bulb filaments and high-speed cutting tools.

Vancouver-based North American Tungsten Corporation Ltd., trading on the TSX Venture under the symbol NTC , is a Tier One junior resource company engaging in mining, developing and acquiring tungsten and other mineral-related properties in Canada. Its 100%-owned Cantung mine and Mactung development project in the Northwest and Yukon Territories make it one of the few tungsten producers with a strategic asset in the western world.

Production in recent months has taken off for NTC, jumping 20% from March to April of this year to a record 30,000 metric tonnes of tungsten concentrate. Unaudited sales figures came in for the first three quarters of fiscal 2007 at nearly $40 million U.S., compared to $45.1 million for all of fiscal 2006.

North American Tungsten reported $51.4 million in revenues at the end of fiscal 2006, a quantum leap from the $158,000 the previous year. NTC stock traded in early August in the $1.35 Canadian range, creating a new 52-week peak, and a far cry from 50-cent Canadian ditch in which it found itself last November.

Simply put, the bargains are out there. Companies like the ones just mentioned are avidly seeking to bring these metals to the surface and make them part of our lives.



We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
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SKPYE:jiefu1996


Beryllium Copper Finger Strips and Industrial Enclosure Shielding

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RFI shielding enclosures and their closure seals

An enclosure is shielded from electromagnetic radiation, especially for testing electronic equipment such as cellular telephones. An electrically conductive housing with a rectangular chamber has open top with a flange extending upward from its perimeter. An electrically conductive closure hinged to the housing has a peripheral groove holding a conductive spring finger assembly. When closed, the flange fits into the spring finger assembly, forcing the fingers apart and against the walls of the groove. This provides excellent conductive connection between the housing and the closure through the flange, the fingers, and the groove. The conductive spring finger assembly is machined from thin beryllium copper strip, formed to final shape into straight portions and corner portions with small radii and then heat treated to retain its final spring form. Claims

What is claimed is:

1. A sealing strip assembly for RFI shielding of an openable closure for an opening in a housing, in which there is a groove having opposed side walls in either one of the closure or the housing and a flange in the other of the closure or the housing, the strip assembly comprising:

a) four substantially straight portions;

b) four corner portions, each corner portion having a radius;

c) each portion having a continuous base with opposed long sides;

d) a plurality of closely spaced apart fingers extending away from each of the long sides and terminating in a free end, such that the fingers on one long side oppose the fingers on the other long side;

e) the fingers on each side having a bend at a point intermediate the free end and the base, the bend directed toward the opposing fingers, such that the space between the opposed fingers at that point is less than the space between the opposed fingers at the free ends;

f) the free ends being arranged to elastically engage the side walls of the groove and then to wipe the side walls as the flange is inserted between the fingers; and

g) the portions being constructed of a thin, electrically conductive material treated after forming to be springy and retain the final straight and corner forms.

2. The strip assembly according to claim 1, in which each of the portions are fabricated separately, and inserted into the groove to closely approximate one another to thereby form a substantially continuous endless shielding strip at the periphery of the closure.

3. The strip assembly according to claim 1, in which a plurality of the portions are formed together, and inserted into the groove to closely approximate one another to thereby form a substantially continuous endless shielding strip at the periphery of the closure.

4. The strip assembly according to claim 1, in which the material of construction is beryllium copper.

5. The strip assembly according to claim 4, in which the material is plated with nickel.

6. A radio frequency shielded enclosure comprising;

a) An electrically conductive housing having a substantially rectangular shape with corners having radii, the housing enclosing a large chamber with an opening;

b) a flange coextensive with the housing and extending away therefrom at the periphery of the opening, the flange having a first thickness;

c) a closure openably connected to the housing configured for closing off the opening;

d) a groove in the closure having opposed side walls and an opening for receiving therein the flange when the closure closes the opening;

e) a sealing strip assembly comprising:

A) four substantially straight portions;

B) four corner portions, each corner portion having a radius;

C) each portion having a continuous base with opposed long sides;

D) a plurality of closely spaced apart fingers extending away from each of the long sides and terminating in a free end, such that the fingers on one long side oppose the fingers on the other long side;

E) the fingers on each side having a bend at a point intermediate the free end and the base, the bend directed toward the opposing fingers, such that the space between the opposed fingers at that point is less than the space between the opposed fingers at the free ends, and slightly less than the first thickness of the flange; and

F) the portions being constructed of a thin, electrically conductive material treated after forming to be springy and retain the final straight and corner forms;

f) the strip assembly being received into the groove to thereby form a substantially continuous endless shielding strip at the periphery of the closure, and

g) the flange arranged to pass freely between the free ends of the fingers and to force the fingers apart and against the groove walls when passing the bends, thereby creating electrical contact between the flange, the fingers and the opposed walls of the groove when the closure is closed.

7. The enclosure according to claim 6, in which the sealing strip assembly is constructed of eight individual portions that are fabricated separately and inserted into the groove in close proximity to one another.

8. The enclosure according to claim 6, in which a plurality of the portions are formed together and then inserted into the groove in close proximity to one another.

9. The enclosure according to claim 6, in which the material of construction of the sealing strip assembly is beryllium copper.

10. The enclosure according to claim 9, in which the beryllium copper is plated with nickel.

11. The enclosure according to claim 6, further comprising a projection at each of the opposed walls of the groove at the open end thereof that engage the free ends of the fingers to prevent the strip assembly from leaving the groove as the flange is removed from the strip assembly.

12. The enclosure according to claim 11, in which the free ends are arranged to elastically engage the opposed side walls of the groove and to then wipe the opposed side walls of the groove as the flange is inserted.

13. The enclosure according to claim 6, in which the free ends are arranged to elastically engage the opposed side walls of the groove and to then wipe the opposed side walls of the groove as the flange is inserted.

14. A radio frequency shielded enclosure comprising:

a) an electrically conductive housing having a particular shape, the housing enclosing a large chamber with an opening;

b) a closure configured for closing off the opening;

c) a flange having a first thickness, the flange being coextensive with either one of the housing or the closure and extending away therefrom at the periphery of the opening;

d) a groove in the other of the closure or the housing, the groove having opposed side walls and an opening for receiving therein the flange when the closure closes the opening;

e) a sealing strip assembly comprising:

A) a plurality of portions;

B) each portion having a continuous base with opposed long sides;

C) a plurality of closely spaced apart fingers extending away from each of the long sides and terminating in a free end, such that the fingers on one long side oppose the fingers on the other long side;

D) the fingers on each side having a bend at a point intermediate the free end and the base, the bend directed toward the opposing fingers, such that the space between the opposed fingers at that point is less than the space between the opposed fingers at the free ends, and slightly less than the first thickness of the flange; and

E) the portions being constructed of a thin, electrically conductive material treated after forming to be springy and retain the final forms required to form a substantially continuous shielding strip at the periphery of the opening;

f) the strip assembly being received into the groove to thereby form a substantially continuous endless shielding strip at the periphery of the closure, and

h) the flange arranged to pass freely between the free ends of the fingers and to force the fingers apart and against the groove walls when passing the bends, thereby creating electrical contact between the flange, the fingers and the opposed walls of the groove when the closure is closed.

15. The enclosure according to claim 14, in which the free ends are arranged to elastically engage the opposed side walls of the groove and to then wipe the opposed side walls of the groove as the flange is inserted.

16. The enclosure according to claim 15, further comprising a projection at each of the opposed walls of the groove at the open end thereof that engage the free ends of the fingers to prevent the strip assembly from leaving the groove as the flange is removed from the strip assembly.

17. A sealing strip assembly for an RFI shielded enclosure, the enclosure having:

an electrically conductive housing, the housing enclosing a large chamber with an opening;

a closure configured for closing off the opening;

a flange having a first thickness, the flange being coextensive with either one of the housing or the closure and extending away therefrom at the periphery of the opening; and

a groove in the other of the closure or the housing, the groove having opposed side walls and an opening for receiving therein the flange when the closure closes the opening;

the sealing strip assembly comprising:

A) a plurality of portions;

B) each portion having a continuous base with opposed long sides;

C) a plurality of closely spaced apart fingers extending away from each of the long sides and terminating in a free end, such that the fingers on one long side oppose the fingers on the other long side;

D) the fingers on each side having a bend at a point intermediate the free end and the base, the bend directed toward the opposing fingers, such that the space between the opposed fingers at that point is less than the space between the opposed fingers at the free ends, and slightly less than the first thickness of the flange;

E) the free ends being constructed to elastically engage the opposed side walls of the groove when inserted therein, and to then wipe the opposed walls of the groove as the flange is inserted for enhanced electrical contact; and

F) the portions being constructed of a thin, electrically conductive material treated after forming to be springy and retain the final forms required to form a substantially continuous shielding strip at the periphery of the opening.

Description

BACKGROUND OF THE INVENTION

This invention relates to enclosures that are shielded from electromagnetic radiation and more particularly to such enclosures and doors that are provided with seals that achieve effective radio frequency shielding by simply closing the door.

DESCRIPTION OF THE PRIOR ART

It is common practice to place apparatus that emits electromagnetic radiation (EMR), or which is sensitive to radio frequency interference (RFI) within a shielded enclosure. When the enclosure must be frequently opened, the means for ensuring that the shielding will be restored when the opening is once again closed present problems. It is well known to provide the access door or panel with a forwardly directed blade along its perimeter that conductively engages separate sealing strips with springy contact fingers conductively held in a groove at the enclosure opening. U.S. Pat. No. 5,223,670 issued Jun. 29, 1993 to Hogan describes such an apparatus and the problems encountered. When cellular telephones are tested, they must be shielded from even the slightest stray radiation. Their emitted radiation must also be shielded when they are tested in a production facility. The closure must be repeatedly opened and closed, as each phone is tested in turn. The closure must be easy to open and close. The unit should take up little space.

LIGI TOOL AND ENGINEERING, INC. OF POMPANO BEACH, Fla. has been producing the RFI-100 Radio Interference Test Box for this purpose. It provides 80 decibel isolation up to 3 GHz. It employs a beryllium copper spring finger strip held captive in the cover that cooperates with a flange extending from the enclosure opening. The strip is series 97-542 produced by INSTRUMENT SPECIALTIES OF DELAWARE WATER GAP, Pa., U.S. Pat. No. 3,504,095. The fingers are spaced apart farther than is desirable to permit some bending of the straight strip. Because the strip cannot be bent through a radius of less than 3 inches, the overall dimensions of the apparatus are larger than is desirable. Construction needed to hold the strip in place adds to the cost. It would be desirable to have a greater degree of shielding, a smaller enclosure, and one that was less costly to produce.

SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide a means of shielding an openable closure that would enable providing smaller radii, greater shielding, less costly construction, and longer useful life without maintenance. The invention comprises a closure seal and an openable RFI shielded enclosure for testing electronic equipment. The seal of the invention comprises a generally U shaped conductive spring finger strip seated in a groove in the cover. The strip comprises a continuous web with springy fingers extending downward therefrom. The strip is comprised of eight portions, four corner portions with small radius, and four straight portions closely adjacent to one another to make an effectively continuous perimeter. The strips are formed into the final desired curved and straight shapes prior to heat treatment. A short flange extends from the housing and is designed to fit into the strip, forcing the fingers of the strip apart to press the legs against the opposed walls of the groove. This provides spring biased electrical contact between the housing, the springy fingers, and the walls of the groove.

These and other objects, features, and advantages of the invention will become more apparent when the detailed description is studied in conjunction with the drawings in which like elements are designated by like reference characters in the various drawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an enclosure of the prior art with cover open.

FIG. 2 is a sectional view taken through line 2--2 of FIG. 1 with cover closed.

FIG. 3 is top view of the enclosure of the invention with cover closed.

FIG. 4 is an end view of the enclosure.

FIG. 5 is a top view of the housing with the cover removed.

FIG. 6 is a sectional view taken through 6--6 of FIG. 5.

FIG. 7 is a side elevation view of the housing.

FIG. 8 is a plan view of the cover from the underside.

FIG. 9 is a sectional view taken through 9--9 of FIG. 8.

FIG. 10 is an enlarged detail of the encircled portion of FIG. 9.

FIG. 11 is a plan view of a corner portion of the gasket after milling and before forming to final shape.

FIG. 12 is a plan view of a short straight portion of the gasket after milling and before forming to final shape.

FIG. 13 is a plan view of a long straight portion of the gasket after milling and before forming to final shape.

FIG. 14 is an enlarged detail as in FIG. 10 with the gasket in place and the cover closed to show the sealing mechanism.

FIG. 15 is a plan view of a portion of the gasket of another embodiment of the invention after milling and before forming to final shape.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now to the drawing FIGS. 1-2, an enclosure 1' of the prior art for testing a cellular telephone 10' is shown. It features a beryllium copper shielding gasket 2' held captive between slot 3' in the cover 4' and the slot 3" in the plate 6'. The gasket 2' has springy fingers 5' which extend laterally until bent inward by the flange 7' on the housing 8' as it closes. The finger before closing is shown in phantom. The radius of the seal is limited by the radius through which the strip may be bent. This determines the dimensions and shape of the finished enclosure. A more rectangular chamber of smaller dimensions would be more useful. The spring fingers are spaced apart by 0.015 inches to permit some bending. Machining the groove 3' with precision is very difficult, and increases the cost of manufacture.

Referring now to FIGS. 3-14, an RFI shielding enclosure 1 of the invention suitable for testing and adjusting cellular telephones is shown. Housing 8 has a substantially rectangular chamber 21 with four straight sides and four corners with small radius. A cover 4 has a slot 3 with four straight sides and four corners with central radius of 0.826 inches that holds captive a beryllium copper springy sealing gasket 2 with generally U shaped spring fingers 11 extending from a continuous base 14. A bend 18 intermediate the free ends 17 of the fingers and the base closes the space between the bends to 0.1476 inches. The fingers are spaced apart from adjacent fingers by only 0.005 for enhanced shielding. The gasket is able to conform to the small radius corners by means of its special construction. It is made up of four straight sections and four corner sections. They are chemically milled out of 0.005 inch beryllium copper strip stock. They are then formed to shape and heat treated to become springy and retain their shape. Tabs 9 may be bent out to retain the sections in holes 5 in the bottom of the slot. The slot 3 is cut out to 0.286 inches wide, and then an intermediate portion of the walls are cut away to 0.3060 inches width, forming projections 10 in groove 3 that hold the gasket sections in place once they are snapped in. The fingers 11 extend outward to touch the side walls of groove 3, and the free ends 17 of the fingers prevent movement past the projections 10 in the groove. The housing 8 has an upwardly projecting flange 12 with a thickness of 0.1520 inches arranged to slide between the bends 18 of fingers 11, forcing them further apart by 0.0024 inches on each side, and pressing the fingers against the side walls of groove 3, thereby making excellent low resistance double contact for enhanced electrical shielding. The beryllium copper gasket is plated with nickel to resist formation of insulating corrosion products. The flange is provided with a rounded edge 13 to facilitate insertion and prevent damage to the gasket. The dimensions of the gasket and the flange are arranged to cause very slight deflection for easy operation and long life, yet with enough wiping and spring action to ensure low resistance contact. The strip is free to move slightly within its groove under the forces of the moving flange 12, causing a wiping contact of the free ends of the strip against the walls of the groove, as well as the wiping contact between the flange and the fingers. Shielded multi pin electrical connector 22 is mounted in an aperture in the side wall.

In an alternative embodiment of the invention, as shown in FIG. 15, the two corner sections may be combined with one short section and two halves of the long sections to fabricate the sealing strip in only two separate identical pieces 20 for ease of manufacture and assembly.

In an alternative embodiment (not shown), the groove may be in the housing and the flange in the closure. The shape of the opening may vary, as desired.

The above disclosed invention has a number of particular features which should preferably be employed in combination, although each is useful separately without departure from the scope of the invention. While I have shown and described the preferred embodiments of my invention, it will be understood that the invention may be embodied otherwise than as herein specifically illustrated or described, and that certain changes in form and arrangement of parts and the specific manner of practicing the invention may be made within the underlying idea or principles of the invention.





We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996


Beryllium Copper Finger Strips and Industrial Enclosure Shielding

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sell Beryllium Copper Finger Strips

Modern electronic equipment often requires EMI Gaskets to avoid radiating EMI/RFI and to prevent susceptibility to outside sources of EMI/RFI. EMI Gaskets designed and manufactured utilizing the strengths of beryllium copper (BeCu) are the industry standard throughout the world. Starting with the emergence of RFI problems in the early days of military electronics, BeCu EMI Gaskets have been the choice solution.

BeCu EMI Gaskets do two things very well:

1. Their mechanical spring characteristics far surpass all other gaskets in the industry.
2. They offer the highest EMI shielding effectiveness.

Clip On 2100	Snap On 2200	Stick On 2300	Twisted Fingers 2400	Angle Fingers 2500	More Fingerstrips

The contact of Beryllium copper finger strips are tolerant of a wiping or sliding action. The EMI Finger strip gaskets are produced in Beryllium copper or stainless steel, both have a high resilient spring quality. This makes the stainless- and beryllium copper finger strips ideal for applications where frequent opening and closing operations are likely. The product is available in a wide range of profiles and is also available in various plated versions.

Beryllium Copper Finger Strips are made from Beryllium Copper (BeCu),
that combine its high electrical conductivity giving high levels of EMI
shielding and grounding, with its spring features, fatigue resistance,
and anti-corrosion make them ideal for high cycle applications in
both compression and in a wiping action and for closure
applications where low closure forces are required. With these
characteristics the strips are suitable for used on closure doors,
electronic enclosures, and boxes where frequently opening and
closing operations are involved.

In order to be effective for maximum electrical contact and shielding
performance, the gasket must be compensate the gap between two
adjoining surfaces that exist due to the gap tolerances, misaligned
and/or irregular surfaces. Therefore, the compression should be
minimum of 25% of the original height, attenuation exceeding 100
dB for most profiles can therefore be achievable


We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996


Beryllium Copper Finger Strips and Industrial Enclosure Shielding

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Radiation resistant closure

A radiation resistant joint between an edge of a movable member and a corresponding edge of a fixed member. The joint comprises at least two bowed conductive contact fingers fixed at one end to one of the members with one finger superimposed over the other finger. The free end of the upper finger engages the bow portion of the lower finger. Means are provided for moving the lower finger and consequently the upper finger away from the member with which they are attached such that the bow portions of each finger engage a conductive plate on the other member to make a radiation resistant seal therewith
.Radiation resistant closures are known in which inflatable tubes are utilized to move flexible conductive contact strips mounted on one member into conductive contact with a plate mounted on another member. An advantage of such a construction is that wear and tear of the contact strips is reduced because the strips are not subjected to the sliding action of the plate passing over the strips during opening and closing movement of the members relative to one another since the tube is inflated only after the members are in a closed position with respect to each other. For example, in U.S. Pat. No. 2,757,225, there is disclosed a door for a radio shielded enclosure having an inflatable tube contained in the edges of a door for a moving contact member made of a thin flexible sheet metal strip into contact with a conductive strip mounted on the edges of a door frame. Because the sheet metal strip is of solid construction, it is important that the door fit accurately in its frame so as to assure that all portions of the strip along its length will be in conductive contact with portions of the door frame when the tube is inflated. The need for accurate and close fitting between the door frame and door necessarily increases cost of production.

Conductive strips in the form of comb-like bowed fingers such as disclosed in U.S. Pat. No. 3,589,070 have been proposed where the bowed portions of the fingers flex outwardly of a member to which they are mounted to conductively engage a conductive plate mounted on another member. The individual fingers are easily flexed so that they will accommodate variations in spacing between the members. However since the strips containing the fingers are made of a light flexible material, such as beryllium copper, the fingers can be easily broken or bent out of shape, which if this occurs, can lead to impairment of radiation seal integrity.

It is therefore an object of my invention to provide for a closure for forming a radiation resistant joint which may utilize the advantages of conductive strips having a plurality of comb-like conductive bowed fingers and which at the same time will insure integrity of a seal even in the event one of the fingers is broken off or bent out of shape.

Broadly a radiation resistant joint according to the invention comprises first and second resilient electrically conductive contact fingers where each finger has a bowed portion comprising a part of a finger strip affixed to an edge of either a movable member or a fixed member. The second resilient fingers are affixed at one end in an overlapping relation to an end of the first fingers with both fingers being connected to an edge of one of the members. The free ends of the second fingers overlap and engages the bowed portions of the first fingers. Bowed portions of both fingers are adapted to engage a conductive plate on the other member with which the fingers are not connected so that the fingers form a conductive seal between the edges of the members.

Preferably the fingers are in a comb-like strip and are made of an electrically conductive material, such as for example, beryllium copper.

Further an inflatable tube is preferably positioned between the first fingers and the member to which it is connected such that when the tube is inflated, it will move the bowed portions of the first fingers and the free ends and bowed portions of the second fingers outwardly towards a conductive plate of the other member. When the tube is in a deflated condition, the natural flexure of the fingers will move the bowed portions of the fingers out of contact with the conductive plate. By this construction the fingers are protected from damage when the members are moved to a closed position with respect to one another where the conductive plate is free to slide over the fingers without contact during opening and closing movement of the members. Further use of an inflatable tube to move the fingers outwardly into conductive engagement with the plate allows the fingers to be positioned in a groove contained in the member the sides of which give further protection against inadvertent damage to the fingers.

The fingers and inflatable tube may be mounted on either the edges of the movable door member or on the edges of a fixed frame member surrounding the door. The conductive plate would be mounted on a corresponding edge of the other member. Preferably the fingers and tube extend around the complete periphery of either the door or fixed frame.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a portion of edges of a door and corresponding edge of a fixed frame having a closure according to the invention in an unsealed position; and

FIG. 2 is a view similar to FIG. 1 showing the closure in a sealing position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1 and 2 there is illustrated a movable door member 1 and a fixed frame member 2 with the door member being in a closed position with respect to the fixed frame member. A first bowed finger 3 is connected at one end to a conductive strip 4 forming part of the door member. A second bowed finger 5 is also connected to the strip 4 and in overlapping relation to the finger 3 such that the free end 6 of the second finger 5 engages the bowed portion 7 of the first finger 3.

The first and second fingers 3 and 5 comprise comb-like strips and are connected to the conductive strip 4 by means of a screw 10 engaging a clamp 11 between which the ends of finger strips are positioned. Other means, for example riveting or welding, could be used to connect the finger strips to the conductive strip.

The door 1 comprises conductive side plates 15 and 16 preferably of a ferrous material so as to provide a shielded structure. An inflatable tube 17 is positioned between the side plates 15 and 16 and is adapted to be connected to a source of fluid pressure, not shown.

The fixed frame member 2 has a side plate 18 comprising ferrous material also forming a shielding structure. A conductive plate 19 is connected to the plate 18 and extends perpendicularly thereto. As shown in FIG. 2 the plate 19 is adapted to be contacted by the bowed portions 7 and 5' of the finger strips 3 and 5 so that a conductive connection is made at two points. Thus if one of the fingers is broken off or bent out of shape, the other finger will continue to make sealing contact with the plate to insure integrity of radiation resilient joints between the members.

The inflatable tube 17 comprises an elastomeric material which has a memory to assume the shape shown in FIG. 1 when deflated to assure that the fingers 3 and 5 may spring or flex out of contact with the plate 19.

The side plate 16 may as shown in the figures extend in the righthand direction beyond the plate 19 so as to provide some degree of protection to the tube 17 and fingers when the door member is in an open position with respect to the frame member.

While the arrangement shown in FIGS. 1 and 2 includes having the fingers and inflatable tube mounted in a door member, the fingers and inflated tube could instead be mounted in a fixed frame member and the conductive plate adapted to contact the fingers would then be part of the door member.

Contact fingers constructed according to the invention are also applicable for use as face seals between a sliding type door which is adapted to slide parallel to a wall to cover or close a wall opening. In this instance the fingers would be affixed to the face of the wall around the wall opening to engage the face of the door, or, alternatively, would be affixed to the face of the door around its periphery to engage the face of the wall around the door opening.

Further while two fingers are shown superimposed, further fingers could be added so as to be superimposed on the second finger 5 if further radio frequency attenuation was desired.

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996


Beryllium Copper Finger Strips and Industrial Enclosure Shielding

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Mechanical design tips for EMI shielding

Nowadays every company is involved with CE / EMI demands. The use of electronics increases as well as the frequencies. Therefore radiation and immunity has to be taken into account in an early stage during the development of new products. In many cases EMI problems cannot be solved at PCB level, the enclosures and cables will have to be shielded.

When to use shielding?

Shielding is a fast way to comply with legal demands like CE or FCC or to prevent electro-magnetic interference. Since time-consuming development is not required, shielding is cost-effective. Therefore shielding is used for non consumer products quantities or if a quick market introduction is needed. It is also used for appliances with high radiation or sensitivity levels or for products of which these levels are not known in advance, like modular enclosures.

Radiation and conduction

Electro-magnetic interference can be transferred by radiation and conduction. Conduction plays an important role with frequencies below 10 MHz. To prevent this, cables and enclosures have to be shielded with magnetically conductive materials. The lower the frequency, the thicker the shielding needs to be. Click HERE for cable shielding solutions.

For high frequencies (HF shielding, >40 MHz), only a very thin layer of highly conductive material is needed.

Avoid gaps

The higher the frequency, the shorter the wavelength. This means that when the frequency increases, the tolerable gap dimensions decrease. In other words: doors, panels and other parts need to be connected electrically on all sides. The easiest way to do this is with highly conductive EMI shielding gaskets. Most of them are self-adhesive for easy mounting.

To select the appropriate gasket, several aspects have to be taken into account: the rigidity of the construction, the distance between the fixings, the distance between them and the construction materials used.



The allowed stiffness of the gasket depends on the rigidity of the construction and the distance between the fixings. If the gasket is too stiff, the door, lid or panel will deflect and gaps will be caused instead of prevented (fig. 1). Especially for doors several kinds of gaskets have been developed, which combine a very large compression range, low closure force and high conductivity. Many of them can be used in existing products, without changing the construction. The gasket selection diagram is very helpful to determine the appropriate gasket material.

Galvanic corrosion

The conductive layer on the outside of the gasket needs to be in the same galvanic range as the construction materials. Otherwise galvanic corrosion will occur and the electrical conduction between the parts will be lost. This will decrease the shielding performance. Commonly used criteria: no more than 0.3 Volts for harsh environments (salt spray / weathering) and no more than 0.5 Volts for benign environments (indoors, salt-free condensation only). Click HERE for an overview of the galvanic range.

To obtain a contact surface within the same galvanic range as the conductive covering of the gaskets, a Metal Tape with conductive self-adhesive can be applied. This can be provided with a masking tape of a smaller width. The paint overlaps the tape, which increases bonding and corrosion resistance (fig 2).

An other way to avoid galvanic corrosion is to take care that the environmental influences do not reach the EMI shielding gasket, for example with a combined EMI / water seal (fig. 3)

Some manufacturers of EMI shielding gaskets use carbon containing layers on the outside to prevent corrosion of the gasket. Please be aware that these are not galvanically compatible with many commonly used construction materials and that corrosion of the contact surfaces of the construction will take place. EMI shielding gaskets with a conductive layer of reinforced Amucor® foil are much more compatible with materials like zinc plated steel and aluminium, and will prevent this kind of corrosion.

Displays / vent panels

Not only connections between construction parts, but of course also displays and vent panels need to be shielded. Displays can be provided with a sputtered transparent Conductive Coating for HF shielding (>30 Mhz, fig 4) or a fine metal wire mesh for lower frequency / high performance shielding (fig. 5). The conductive sputter layer can be coated directly on the display or can be supplied on thin films for smaller amounts.

Of course, the shielding of the displays will have to be connected with the shielding of the enclosure to guarantee optimal damping. This can be done with a gasket or metal tape with conductive self-adhesive.

Vent Panels are usually shielded with aluminium honeycomb vents. These give excellent shielding performance with minimal loss of airflow. For superb shielding performance so-called cross-cell honeycomb vents are used. These consist of two or more layers of aluminium honeycomb, rotated 90° (fig. 6). Honeycombs are usually applied with a rigid aluminium frame and a gasket of 2-5 mm for optimal connection with the construction.

Cables

To prevent radiation from escaping past the shielding through power and signal cables, they need to be shielded or filtered. Shielding can be provided by ready-made shielded cables, shielding tube and cable wrapping. Shielding tube consists of hollow braided metal wire, through which the cable or bundle of cables can be pulled to shield it. Cable Wrapping is a knitted metal wire tape, which is wrapped around a cable or bundle of cables. With this, it is very easy to make branches.

The shielding of the cables always needs to be connected properly with the shielding of the enclosure; otherwise the cable will act as an antenna and the shielding will be useless. For heavy duty and military applications, shielded cable glands and special cable entry systems with compressed conductive rubber seals are commonly used. For commercial applications and appliances that do not need a water seal, Entry-shield is used in most cases. Entry-shield consist of two pre-compressed flexible strips of EMI shielding gasket, between which the cables are entered. This way, many cables can be entered simultaneously with minimal mounting and it is very easy to add cables later (fig. 7).

Connectors

What was said about cables also applies for Connectors. These also need to be shielded or filtered and connected with a gasket. These gaskets can consist of 1mm thick die-cut material, which can also be manufactured easily according to customer specifications, with little tooling costs (fig. 8).

Shielding at the source

If the source of the radiation or sensitivity is known, shielding can be done at the source. The interfering parts can be packed in a folded box or envelope of die-cut shielding foil with an insulating layer on the inside to avoid short-circuiting (fig. 9). It can also be done by soldering vertical metal strips on the PCB to create compartments. These compartments are closed by adding a lid of flexible die-cut shielding foil (fig. 10) or by pressing a soft foam sheet with a conductive surface against the strips (fig. 11). With the latter option, many compartments can be shielded with just one single cover.

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996


Beryllium Copper Finger Strips and Industrial Enclosure Shielding

...
Read more...