A NUT HOLDING THRUST BEARING AND HIGHLY HERMETICAL SEALING FLUID JOINT WITH THE SAME NUT

Abstract: A nut adapted to be formed to hardly twist a pipe (14) welded to a cap nut (11) clamping fluid joint to eliminate the twist of the pipe when clamping the cap nut of the fluid joint, and a fluid joint having the nut. This nut holds a thrust bearing (17) at a position of the nut, corresponding to the surface of the nut for pressing a pipe (14) when clamping the nut so that, when an unreasonable force is applied, the nut and the pipe rotate together so as not to transmit a rotary torque to the pipe.

Description: BACKGROUND OF THE INVENTION This invention relates to a nut adapted to eliminate the transmission of a rotary torque produced by clamping a nut to a conduit and a highly hermetically sealing fluid joint for a semiconductor fabricating apparatus provided with the same nut. The necessity of fabricating a remarkably large scale integrated circuit has recently occurred as in a super LSI or superhigh LSI in the high acceleration of technical advancement. Since there is a requirement of using extremely toxic gaseous fluid such as silane, arsine or phosphine and forming a film of high purity in a superhigh vacuum so as to fabricate such a large scale integrated circuit, this semiconductor fabricating apparatus is necessitated to maintain highly hermetical sealability. However, in order to couple the fluid passage forming elements of such a semiconductor fabricating apparatus, it is impossible to couple by welding all the elements, and the fabricating apparatus cannot be completed unless there is no fluid joint having excellent hermetical sealability. There exist various types of joints used for this purpose, and there is representatively a fluid joint which, as shown in Fig. 8, couples two sleeves 1 and 2 through a gasket 3 by engaging a nut 5 clamped on the other sleeve 2 with a gland 4 formed with threads on the outer periphery on which the sleeve 1 is mounted. Since such a cap nut clamping has advantages of simplicity and no large space, the cap nuts are frequently employed in case of conduits of small diameter, but the cap nut still has drawbacks that a rotary torque is applied to the sleeve 2 due to a friction between the cap nut (female nut) 5 and the sleeve 2 and a conduit welded to the sleeve 2 is twisted due to the rotary torque and the surface of the gasket is scratched by the rotation of the sleeve 2 with the result that the fluid leads therefrom. In order to prevent the fluid in the conduit from leaking, there is generally employed a method of clamping the cap nut while suppressing the rotation of the sleeve 2 by contacting a spanner with the chamfered position 6 of the sleeve 2 by chamfering the sleeve 2. However, since this method must suppress the rotations of the gland 4 and the sleeve 2 at the two positions and must also clamp the cap nut 5, it is impossible to operate these steps by one worker, and since the steps have to be worked very carefully, there is a drawback that the working efficiency is remarkably deteriorated. The inventor of this invention has invented an improved nut in which, as shown in Fig. 9, a number of small spheres 8 are held in a ring-shaped groove 9 on the surface of a cap nut 7 to be contacted under pressure with a sleeve 2 so as to eliminate the abovementioned drawbacks. However, since this improved nut can eliminate the abovementioned drawbacks of the conventional nut, but the small sphere holder of the nut is required to be precisely machined to cause the nuts to have wrong productivity, and there is possibility of damaging the small sphere holder if the nut is clamped by a higher torque than the specified value due to the mistake of a worker, and since the small spheres 8 are contacted at points with the sleeve 2, there arises another difficulty that the strengths of the small spheres are weakened. BRIEF SUMMARY OF THE INVENTION An object of this invention is to provide a female nut or a male nut which eliminates all the abovementioned drawbacks and disadvantages and obviates the transmission of a rotary torque to a conduit due to the rotation of the female or male nut and a sleeve when clamping the female or male nut. Another object of this invention is to provide a highly hermetical sealability fluid joint for a semiconductor fabricating apparatus which has the abovesaid female or male nut. Yet another object of this invention is to provide a highly hermetical sealability fluid joint for a semiconductor fabricating apparatus which has no possibility of damaging a small sphere holder. Still another object of this invention is to provide a highly hermetical sealing fluid joint for a semiconductor fabricating apparatus which can hold high hermetical sealability over a long period of time. The above and other related objects and features of the invention will be apparent from a reading of the following description of the disclosure found in the accompanying drawings and the novelty thereof. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a sectional view showing an embodiment of a nut according to the present invention; Fig. 2 is a fragmentarily sectional view of a fluid joint using the nut of the present invention; Fig. 3 is a partially fragmentarily sectional view of a gasket employed in the fluid joint of the invention; Fig. 4 is a sectional view showing another embodiment of a nut according to the present invention; Fig. 5 is a fragmentarily sectional view of a fluid joint using the nut of the invention; Figs. 6 and 7 are sectional views showing still another embodiment of a fluid joint using the nut of the invention; Fig. 8 is a sectional view showing a conventional fluid joint; and Fig. 9 is a sectional view showing fluid joint of the state that a female nut holding small spheres and a sleeve are associated. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of this invention will be described in detail with reference to the accompanying drawings, wherein the same reference numerals designate the same or corresponding parts and components through the drawings. Fig. 1 shows an embodiment of a nut according to the present invention. An engaging recess 12 is formed on the surface of a female nut (cap nut) 11 in pressure contact with a sleeve, a threaded portion 28 is formed on the inner peripheral surface of the female nut 11, and a thrust bearing 17 is press-fitted to and held in the engaging recess 12 of the female nut 11. In the thrust bearing 17 used in the embodiment described above, a plurality of spheres 35 are filled in an annular grooves between an inner race 33 and an outer race 34, and an annular element 36 is engaged with the outer peripheral surfaces of the inner and outer races 33 and 34. Fig. 2 shows a fluid joint using the abovementioned female nut 11. A body 13 is contacted through a gasket 15 with a sleeve 14 to form a fluid passage. The female nut 11 is exemplified to be engaged with the outer periphery of the sleeve 14 and with the threaded portion 19 of the outer peripheral surface of the body 13 so that the sleeve 14 is clamped through a gasket 15 with the body 13. A flange 16 is formed on the outer peripheral surface of the end of the sleeve 14, and a thrust bearing 17 held in engagement with the female nut 11 is contacted with the flange 16. Thus, even if the cap nut 11 is excessively clamped, the cap nut 11 and the sleeve 14 rotate together so as not to transmit the rotary torque to the sleeve 14. The gasket 15 used in the fluid joint is constructed, as shown in Fig. 3, to coat a coil spring 20 on a ring-shaped metal coating element 18 so as to space the outside center. High hermetical sealability is imparted to the fluid joint by using such a gasket 15. In the fluid joint described above, an annular recess 21 is formed on the contacting surface of the sleeve 14 with the gasket 15, and a projecting 22 to be engaged within the recess 21 is formed on the surface of the body 13 contacted with the gasket 15. Thus, when the gasket 15 is contacted under pressed with the sleeve 14 to the effective elastic compression amount, the stepped portion 23 of the projection 22 is stopped at the end face 24 of the body 13. Thus, the gasket 15 is not compressed more than the effective elastic compression amount to effectively prevent the gasket 15 from being damaged. In the fluid joint described above, the contacting surface of the body 13 through the gasket 15 with the sleeve 14 is subjected to a roll burnishing process. When thus subjecting to the roll burnishing process, the surface of the body 13 is surface-hardened to improve the surface hardness of the body 13 so that the surface of the body 13 is hardly scratched or damaged with the result that ultrafine linear scratches to cause the gasket 15 to be deteriorated in the hermetical seal are hardly formed in the gasket 15 formed by coating the coil spring 20 with the metal coating element 18. Thus, the gasket 15 may be repeatedly used. Consequently, the fluid joint in which the gasket 15 is used can maintain highly hermetical sealability for a long period of time. The roll burnishing process may be conducted by a method of contacting the rolling roll or rolls with the contacting surfaces of the body and the sleeve with the gasket. For example, when the sealing surface of the fluid joint of the above embodiment is cut in the roughness of 3.2S and is then subjected to the roll burnishing process. the mirror-polished surface of roughness of approx. 0.8S may be readily provided by the machining time for 1 to 2 sec. The surface hardness of the body and the sleeve can be improved by this burnishing process (in case of stainless steel, the hardness of the base material is improved from 180 HB to 300HB or higher). Thus, the sealing surfaces of the body and the sleeve are hardly scratched. Fig. 4 shows another embodiment of a nut according to the present invention. A thrust bearing 17 is engaged with an engaging recess 26 formed on the end of a male nut 25. A threaded portion 27 is formed on the outer peripheral surface of the male nut 25. Fig. 5 shows a fluid joint which uses the abovementioned male nut 25 of the invention. Two sleeves 16 and 16′ are coupled through a gasket 15 by engaging a female nut 32′ with the threaded portion 27 of the outer peripheral surface of the male nut 25 which is engaged with the outer peripheral surface of the sleeve 16′. In this case, when the female nut 32′ is excessively clamped, the male nut 25 and the sleeve 16′ rotate together through the thrust bearing 17. The nut of the invention may also be used not only in the fluid joint constructed as described above, but in other utility that a rotary torque is undesirably transmitted in case of clamping by threads. For example, as shown in Figs. 6 and 7, a nut is used as a male nut 25 or a female nut 11 for hermetically sealingly clamping a pressure sensor 29 with a body 30. In this case in the conventional nut, a bearing is generally used. However, if a dimensional limit is incorporated, there is a drawback that the bearing of special dimension is expensive in small quantity. According to the present invention, since the ball bearing effect is directly imparted to the nut, the nut provides various advantages that the nut can be freely designed inexpensively.

Claims: 1. A female or male nut which comprises: holding a thrust bearing held at a position thereof corresponding to the surface of said female or male nut for pressing a sleeve by said female or male nut when clamping the female nut or the male nut . 2. The nut according to claim 1, wherein an engaging recess is formed on the surface of said female nut for pressing under pressure said sleeve, and said thrust bearing is press-fitted to the engaging recess of said female nut. 3. The nut according to claim 2, wherein said thrust bearing comprises an inner race and an outer race, and a plurality of small spheres filled in an annular groove formed between the inner race and the outer race, and an annular element engaged on the outer peripheral surfaces of the inner and outer races. 4. A highly hermetical sealability cap nut clamping fluid joint for a semiconductor fabricating apparatus comprising: a body having a threaded portion formed on the outer peripheral surface of one end of said tubular body; a gasket; a tubular sleeve having a flange formed on the outer peripheral surface of the end thereof for communicating in contact with a through hole of said body at the threaded portion side through said gasket, and a female nut engaged with said sleeve for rigidly clamping said body and said sleeve by engaging with the threaded portion of said body, said female nut having an engaging recess formed on the surface thereof to be contacted under pressure with said sleeve, said thrust bearing being press-fitted to the engaging recess of said female nut, said gasket being coated with a coil spring by a metal coating element to space the outside center thereof. 5. The highly hermetical sealability cap nut clamping fluid joint according to claim 4, wherein said body and said sleeve are subjected to a roll burnishing process on the surfaces to be contacted through said gasket. 6. The highly hermetical sealability cap nut clamping fluid joint according to claim 5, wherein engaging recess and engaging projection are formed on the contacting surfaces of said body and said sleeve through said gasket in such a manner that the end face of the engaging recess of said body is contacted with the stepped portion of the engaging projection of said sleeve so as not to be compressed more than effective elastic compression amount. 7. A highly hermetical sealability cap nut clamping fluid joint for a semiconductor fabricating apparatus having a female or male nut comprising: two sleeves; a gasket, said two sleeves being coupled through said gasket by engaging the threaded portion of said male nut engaged externally with one sleeve with said female nut externally engaged with the other sleeve, said male nut having an engaging recess formed on the pressure-contacting surface thereof with said sleeves, a thrust bearing press-fitted to the engaging recess of said male nut, said gasket having a coil spring so coated on said gasket by a metal coating element to space the outside center thereof. 8. The highly hermetical sealability cap nut clamping fluid joint according to claim 7, wherein said body and said sleeve are subjected to a roll burnishing process on the surfaces to be contacted through said gasket. 9. The highly hermetical sealability cap nut clamping fluid joint according to claim 8, wherein engaging recess and engaging projection are formed on the contacting surfaces of said two sleeves through said gasket in such a manner that the end face of the engaging recess of said body is contacted with the stepped portion of the engaging projection of said sleeve so as not to be compressed more than effective elastic compression amount.

Inventors: YAGISAWA, SHIGERU
Applicants: TOYOKO KAGAKU CO., LTD.
Application year: 1987
Main classification: F16L27
IPC codes: F16L19, F16L27, F16B37