DD285522A7 - ULTRA HIGH VACUUM Floating dredgers - Google Patents

Abstract

The invention relates to a UHV-tight Drehdurchfuehrung with directly into the interior of the recipient / the device reaching wave is suitable for the transmission of a large torque and without risk of flooding for the supply rotatory moving internals with flowing media. The task of specifying a permanently UHV-tight Drehdurchfuehrung that is bakeable and whose materials have only a minimum vapor pressure is achieved by dasz the shaft of Drehdurchfuehrung on the side surface of their shaft collar or on a short portion of their shell with a plurality of concentric or is provided with parallel slightly rounded cutting rings which are pressed against a skin, only one tenth of a millimeter thick, of a flowable plastic material. {UHV-tight; Floating dredgers; Recipient; Wave; large torque; Risk of flooding; Media supply; Variety of cutting rings, concentric, parallel; Plastic material}

Description

For this 1 page drawings

Field of application of the invention

The invention relates to an ultra-high-vacuum-tight rotary feedthrough with a shaft extending directly into the interior for recipients, containers or base bodies, where for any reason (eg evacuation, highest purity) UHV tightness is required as well as high torque transmission and / or rotationally moved internals be supplied with flowing medium (eg coolant) without any direct risk of flooding.

Characteristic of the known state of the art

Known solutions for UHV rotary unions transmitted by bellows arrangements or flexible sheet metal structures rotary movements without breakthrough of the vessel wall indirectly in the vacuum. An identical result can be achieved by means of magnetic forces.

To produce such rotary feedthroughs, rotatably moved internals must be supplied separately with fluids flowing in the operating state (eg coolant), so that there is an immediate risk of flooding because the stuffing box packings, lip seals, O-rings or shaft sealing rings used are conceivable in all imaginable ways While variants can approach the lower limits of the UHV leak rates under optimal conditions, they can not reliably maintain impermeability from the very outset, but they can not be reliably maintained during the rotational movement.

From the high-pressure sealing technique, systems are known which arrange a plurality of individual seals one behind the other and provide stepwise transitions between different pressure levels, e.g. in SU 793068 or 1002710. Frequently, barrier fluid is used, such as. 3. in DE 3441351. The vacuum sealing technique pumps z.T. between two sealing points with backing pumps

In DR 679948, a high-pressure flange is closed by several concentric cutting rings, with a pressure reduction taking place from annular chamber to annular chamber. In DD 223786, a UHV valve is locked by two metal cutting edges which are moved toward one another with a plastic sealing ring (eg made of PTFE) arranged between them. Rotary movements are not provided in these solutions.

According to FR 2456275 and SU 1236242 seals the wavy shaped inner surface of a tube on the cylindrical surface of a shaft, wherein a pressure reduction takes place from one annular chamber to the other. DD 254631 provides two concentric grooves with sliding insert in a housing to seal in which engages a wave labyrinth. However, none of the three solutions is intended or suitable for UHV seals because the gain in the stepwise pressure transfer is abandoned elsewhere. The last solution leaves completely open how the seal should come about immediately along the shaft. However, that would be crucial for a UHV seal.

Object of the invention

The invention has a simple and inexpensive to produce ultra-high vacuum-tight rotary feedthrough to the goal, in the very large torques transmitted by a projecting directly into the vacuum or the clean dream wave or / and rotatably moving internals with a medium (eg., Coolant) can be supplied , It depends on extremely low leakage rates far into the UHV range, which are reliably maintained even under operating conditions of slow rotational movement.

Explanation of the essence of the invention The invention is based on the object, a permanently UHV-tight rotary feedthrough for a directly into the evacuated Specify space or the clean room protruding wave, transmitted with the large torque and in the required Traps media streams (eg., For cooling) can be transported to slowly rotating internals. necessary Secondary conditions, such as minimum vapor pressure of the materials used and Mindestausheiztemperatur must

also be respected.

The object of the invention is achieved in that the shaft of the rotary feedthrough on the side surface of their shaft collar,

on a short piece of the cylinder jacket or on a cone piece with a large number of concentric or parallel teeth, with their tips provided with slightly rounded cutting rings, and that the truncated sealing blades act against one only

Tenths of a millimeter of skin flowable and self-lubricating plastic material (eg PTFE without or with

slip-promoting filler) are pressed and form in this many concentric or parallel sealing grooves. Every couple is one

UHV closure and reduces the pressure in a cascade of successive annular chambers gradually from. The object of the invention can also be solved by the fact that the plurality of cutting rings / sealing cutting in the stationary Wall of the housing / recipient be incorporated or that they face each other in the shaft and wall

are located.

Special care has according to the invention only in the manufacture of cutting rings / sealing cutting in the field of their sliding To contact with the sealing skin, where the surface quality must reach polish values, so that no abrasion In the case of a UKY recipient, the pressure can be lowered far into the UHV range, because apart from this sealing joint

There is no other way into the interior for gases and / or impurities. Even during the movement phase, there are no temporary leaks that could lead to leaving the UHV range.

Are truncated sealing edges and sealing grooves as a concentric ring chamber cascade at the Side surface of a WeJlenbundes, then according to the invention only a thin, a few tenths of a millimeter thick Gasket made of flexible and lubricious plastic used to achieve UHV tightness. The pressure difference can simultaneously for

a flexible contact pressure to be exploited.

The groove system is located on a cylinder jacket, so according to the invention shaft and coated sealing tube

pushed into a front slightly keglige and otherwise adapted bore so that the truncated rings in the

Press in the sealing tube and form sealing grooves in which they slide. The same applies to a ring chamber cascade on the cone piece of a shaft. Again, by the pressure difference a

flexible contact force can be generated. The sealing hose must be conical. Din mounting is not a problem.

Mechanical loads, in particular lateral components of large acting on the actuating shaft forces must

be intercepted by conventional bearings.

The temperature resistance of the plastic material limits the bakeability. The invention aims at expenses where a Bakeout temperature of 250 ° C is sufficient. To diffuse as little gas as possible through the plastic material,

The invention is based on an extremely thin, only tenths of a millimeter amount of skin made of plastic material in a narrowmotallbegrsnzten annular gap.

The invention realizes a simple to produce UHV-tight rotary feedthrough, which can be up to large diameters without

can produce large time and cost and both for sealing extremely evacuated as for other reasons

UHV-tightly closed spaces is suitable. It is able to transmit high torques and allows the supply

rotating internals with an externally charged and driven media circuit (eg coolant circuit) without

Danger of flooding over moving media seals within the evacuated room or clean room. Only for the production of concentric or parallel rings special care is required. In the sliding area

Very tight tolerances for geometric deviations and perfect polishing must be prescribed. The sealing skin may not be deformed or injured in the operating state. Above all, no abrasion of the plastic material may occur.

Exemplary embodiments FIGS. 1 to 6 show exemplary embodiments of the invention Fig. 1: Rotary feedthrough without through hole for indoor installation, 2: magnification representation of the annular chamber cascade, Fig. 3: Rotary feedthrough with through hole for outdoor installation, Fig.4: sealing grooves in the housing, 5: sealing grooves in the cylinder jacket of the shaft, Fig. 6: sealing grooves on a conical surface of the shaft.

Fig. 1 shows a rotary union according to the invention with non-drilled shaft 1, wherein the last ro from the evacuated room or from the clean room 3 forth through the container wall 2 is inserted. The collar of the shaft 1 has laterally concentric grooves, which terminate in blunt cutting rings (radius 0.01 ... 0.1 mm). Between this structure of concentric sealing rings (truncated cutting rings) and the wall 2 of the container is only a tenth of a millimeter thin disc 4 made of flowable, self-lubricating plastic material (eg PTFE without or with Gleitförderndem filler) clamped, in which concentric grooves form during pressure. The sealing rings slide in these grooves, are - each one of them - a UHV closure, bulkhead annular chambers and result in a gradual pressure transition from chamber to chamber.

The resulting ring chamber cascade according to the invention is illustrated for all examples in the magnification illustration FIG. In the area of contact of the rings 6 with sealing disk 4, high precision and surface quality are required (eg tolerances ± 0.01 ... 0.05 mm, approximately Rz 0.8). The counterface requires no special preparation. Here, the usual surface quality for mating surfaces is sufficient.

DiJ required force F is z. B. applied by a spring or in any other way. Here can also the media print

be exploited in a clean dream 3.

Since the shaft 1 projects directly into the evacuated space or clean dream 3, high torques can be transmitted

become. Large on-shaft 1 attacking unwanted forces, especially with lateral component, are intercepted by one or more conventional bearings 5.

Fig. 3 shows a similar arrangement, but with through hole and externally inserted shaft 1. If it is

a vacuum recipient and conventional bearings 5 (for example, slide bearings) allow this to occur

Pressure difference to the evacuated space 3 toward forces that pull the shaft collar flexible against the gasket 4. The same applies to Fig. 4, where the concentric sealing rings 6 are incorporated in wall 2. Again, over the bore of the Shaft 1 a medium flow (for example, a cooling liquid) in rotationally moving internals flow in and out. The advantage exists

above all, that liquid seals within the space 3 are static and reduce the risk of flooding.

FIGS. 5 and 6 finally show the realization of the presented sealing principle with grooves on cylindrical or conical Mantle surface of a shaft 1 with or without bore, the arrangement in turn from the outside, but also from the inside mountable

can be designed.

The various embodiments must be adapted specifically to the intended purpose. All variations

have a plurality of pairings between seal cutting and generated in the plastic skin sealing grooves 6 (sliding grooves) or

Pressure points on the counter surface. Each of the seal-seal pairs is a UHV shutter. The

between them resulting cascaded ring chambers together form a ring chamber cascade mitinsgesamt extremely low leakage rate, which is also under operating conditions, d. H. while slow rotational movement is reliably maintained.

Apart from the inevitably high precision of the concentric or parallel sealing rings / sealing edges, this throws

presented sealing principle no manufacturing problems. The production costs are therefore low.

The criterion for perfect quality of the UHV seal is, in addition to the leak test, a visual inspection of the sealing skin

possible abrasion after test run. If such forms, the sliding area must be polished.

Claims (6)

1. Ultra-high vacuum rotary feed-through with pressure gradual reduction between the pressure levels using a flowable, self-lubricating plastic material, characterized in that a plurality of concentric or parallel cutting rings is pressed against a few tens of millimeters thick plastic sealing skin pressed. 2. Ultra-high vacuum rotary feedthrough according to claim 1, characterized in that the plurality of concentric cutting rings is arranged on the side surface of a shaft collar. 3. ultra-high vacuum rotary feedthrough according to claim 1, characterized in that the plurality of parallel cutting rings is arranged on the lateral surface of a shaft. 4. ultra-high vacuum rotary feedthrough according to claim 1, characterized in that the plurality of concentric or parallel cutting rings is incorporated in the fixed part of a recipient. 5. ultra-high vacuum rotary feedthrough according to claim 1, characterized in that there are a plurality of concentric or parallel cutting rings both in the rotatable and in the stationary part of a recipient. 6. ultra-high vacuum rotary feedthrough according to claim 3, characterized in that the lateral surface of the shaft is designed cylindrical or conical.