JP2010261573A - Corrosion-resistant bellows type mechanical seal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a corrosion-resistant bellows type mechanical seal which can favorably seal a corrosive fluid even under a high-temperature condition. <P>SOLUTION: The corrosion-resistance bellows type mechanical seal comprises: a ceramic stationary sealing ring 2 fixed to a seal case 1; a PTFE-made bellows 4 which is fittingly fixed to a rotating shaft 3 at its base end 4b, and can be elongated and contracted in the axial direction; a rotating sealing ring 5 which is connected to the tip 4d of the bellows 4, opposes the stationary sealing ring 2, and is constituted of a hard resin material excellent in corrosion resistance and sliding performance with the stationary sealing ring 2; a spring retainer 6 which is engaged with the tip 4d of the bellows 4 and the rotating sealing ring 5 so as to be not rotative with respect to the tip and the rotating sealing ring, and not to be displaceable with respect to the direction of the stationary sealing ring; and a spring member 7 which is arranged in a region at the external peripheral side of the bellows 4 so as to press and energize the spring retainer 6 in the direction of the stationary sealing ring. The spring retainer 6 is constituted of a resin material whose thermal expansion coefficient is equal or similar to that of the bellows 4. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is a corrosion-resistant bellows used as a shaft seal device for rotating equipment that requires a high degree of corrosion resistance (chemical resistance, acid resistance, alkali resistance, seawater resistance, etc.) in the fields of pharmaceuticals, foods, semiconductors, etc. This relates to a mechanical seal.

  As a bellows type mechanical seal, for example, as disclosed in Patent Document 1, a stationary seal ring fixed to a seal case, a bellows that can be expanded and contracted in an axial direction with a base end portion fitted and fixed to a rotating shaft, and a tip of the bellows A rotary seal ring integrally formed with the stationary seal ring, a spring retainer fitted and connected to the tip of the bellows so as not to rotate relative thereto, and a bellows of the bellows to press and bias the spring retainer in the direction of the static seal ring. A sealed fluid region which is an inner peripheral side region of the relative rotational sliding contact portion by a relative rotational sliding contact action of the sealing end surface which is an opposing end surface of both sealing rings. And a non-sealed fluid region that is an outer peripheral side region thereof are known.

  By the way, such a bellows type mechanical seal is a shaft seal device for a rotating device that requires high corrosion resistance (chemical resistance, acid resistance, alkali resistance, seawater resistance, etc.) in the fields of pharmaceuticals, foods, semiconductors, and the like. However, when used in applications that require such corrosion resistance, that is, when the sealed fluid is a corrosive fluid, the bellows contacting the sealed fluid are resistant to corrosion and heat. It is made of PTFE (polytetrafluoroethylene) which is excellent in

JP-A-8-261333

  However, since the spring retainer does not come into contact with the sealed fluid, it is not necessary to select the material in consideration of the properties (corrosiveness, temperature) of the sealed fluid. It is usually composed. Therefore, under a high temperature condition, a difference in thermal expansion occurs at the fitting portion between the spring retainer and the bellows, which causes an excessive load (stress) to act on the bellows. As a result, bellows type mechanical seals using PTFE bellows cannot provide a good sealing function, and have high corrosion resistance (chemical resistance, acid resistance) in fields such as pharmaceuticals, foods, and semiconductors. , Alkali resistance, seawater resistance, etc.) are extremely inappropriate as shaft seals for rotating equipment.

An object of the present invention is to provide a corrosion-resistant bellows type mechanical seal that can satisfactorily seal a corrosive fluid even under high temperature conditions without causing such problems.

  A corrosion-resistant bellows type mechanical seal of the present invention that has solved this problem is a ceramic stationary seal ring fixed to a seal case, and a PTFE bellows that can be expanded and contracted in the axial direction with a base end portion fitted and fixed to a rotating shaft. And a rotary seal ring made of a hard resin material that is connected to the tip of the bellows and faces the static seal ring and has excellent corrosion resistance and sliding characteristics with the static seal ring, and the tip of the bellows and the rotary seal A spring retainer engaged with the ring so that it cannot rotate relative to the stationary seal ring, and a spring member disposed in an outer peripheral region of the bellows to press and bias the spring retainer in the direction of the stationary seal ring And a sealed fluid region which is an inner peripheral side region of the relative rotational sliding contact portion and a non-existing region which is the outer peripheral side region by the relative rotational sliding contact action of the sealing end surfaces which are the opposite end surfaces of both sealing rings. A sealing fluid region be one that is configured to seal is a spring retainer which thermal expansion coefficient is constituted by a resin material for the bellows equal or approximate. In a preferred embodiment of such a bellows type mechanical seal, the rotary seal ring is made of a composite resin material mainly containing PTFE, and the spring retainer is made of a composite resin material mainly containing PTFE.

  The corrosion-resistant bellows-type mechanical seal of the present invention is composed of a hard seal-resistant resin material that is superior in sliding characteristics with a mating seal ring (stationary seal ring) rather than PTFE, which is a constituent material of the bellows, in the rotary seal ring. Therefore, the corrosive fluid can be satisfactorily sealed even under high temperature conditions. Moreover, since the spring retainer is made of a resin material whose thermal expansion coefficient is equal to or close to that of the bellows, an excessive load does not act on the bellows due to the difference in thermal expansion between the two, and even under high temperature conditions. A good sealing function can be exhibited.

FIG. 1 is a longitudinal side view showing an example of a corrosion-resistant bellows-type mechanical seal according to the present invention. FIG. 2 is a longitudinal side view showing a modification of the bellows-type mechanical seal.

  Hereinafter, the form for implementing this invention is demonstrated concretely with reference to FIG. FIG. 1 is a longitudinal side view showing a corrosion-resistant bellows-type mechanical seal according to the present invention.

  The bellows type mechanical seal shown in FIG. 1 is used as a shaft seal device in a rotating device such as a stirrer that handles a corrosive fluid under a high temperature condition, and includes a seal case 1 attached to a housing of the rotating device, and a seal. A stationary seal ring 2 fixed to the case 1 and a rotary shaft 3 of a rotating device that penetrates the seal case 1 concentrically in the vertical direction are held axially movable (movable in the vertical direction) via a bellows 4. The rotary seal ring 5 and the spring member 7 that presses and contacts the rotary seal ring 5 to the stationary seal ring 2 via the spring retainer 6, Due to the relative rotational sliding contact action of 5a, an in-machine region (sealed fluid region) A that is the inner peripheral side region of the relative rotational sliding contact part 2a, 5a and an outer region (non-sealed fluid region) that is the outer peripheral side region. B and It is configured end surface contact type mechanical seal to 蔽 seal. Note that the fluid (sealed fluid) in the in-machine region A is a corrosive high-temperature, high-pressure gas or liquid, and the in-machine region B is an atmospheric region.

  The seal case 1 is a cylindrical body made of metal (SUS304 or the like) having a circular inner peripheral surface, a case main body 1a attached to a housing (not shown) of a rotating device, and a collar 1b connected thereto. It consists of. A cylindrical guide 1 c is formed on the inner peripheral portion of the case body 1 so as to surround the rotary shaft 3 and project to the inner peripheral portions of the sealing rings 2 and 5. A lining layer 1d of a corrosion-resistant resin material (PEEK or the like) is formed on the surface portion of the seal case 1 that comes into contact with the fluid to be sealed (the fluid in the in-machine region A).

  The stationary sealing ring 2 is an annular body fitted and fixed to the inner peripheral surface of the collar 1b, and the tip end surface is configured as a sealing end surface 2a which is a smooth annular plane orthogonal to the axis. The stationary seal ring 2 is made of ceramics having excellent corrosion resistance. In this example, the stationary seal ring 2 is made of silicon carbide. Corrosion-resistant material O-rings 8 and 9 are interposed between the stationary seal ring 2 and the case main body 1a and the collar 1b to seal the fitting portion between the seal case 1 and the stationary seal ring 2 (two Next seal). In this example, the O-rings 9 and 10 are made of perfluoro rubber.

  The bellows 4 is made of PTFE (polytetrafluoroethylene), has a cylindrical shape with an intermediate portion having a meandering cross section 4a, and a fixed portion 4b as a base end portion made of metal ( SUS316 or the like) is firmly fitted and fixed to the rotary shaft 3 via a stopper ring 10, a tightening ring 11 and a fixing ring 12. That is, the stopper ring 10 is fixed to the rotary shaft 3 by tightening an appropriate number of set screws (only one is shown) 13 screwed to the stopper ring 10 to the rotary shaft 3. The tightening ring 11 is formed by a truncated conical cam surface 11 a whose inner peripheral surface is expanded toward the stopper ring 10, and an appropriate number (only one is shown) of tightening bolts 14 is provided on the stopper ring 10. It is attached by. The fixing ring 12 is externally fitted to the base end 4b while being engaged with an annular protrusion 4c formed on the base end 4b of the bellows 4, and the outer peripheral surface is fitted to the cam surface 12a of the tightening ring 11 It is formed on the truncated conical cam surface 12a. Therefore, by tightening the tightening bolt 14 and moving the tightening ring 11 in the direction close to the stopper ring 10, the base end portion 4 b of the bellows 4 is rotated by the cam surfaces 11 a and 12 a via the fixing ring 12. It is designed to be firmly fixed to the surface.

  The rotary seal ring 5 is an annular body made of a hard resin material excellent in corrosion resistance and sliding characteristics with the stationary seal ring 2, and its end face is a sealed end face that is a smooth annular plane perpendicular to the axis. 5a. The rotary seal ring is a composite resin material mainly composed of PTFE, and PTFE is filled with an appropriate filler in order to improve sliding characteristics (low friction property) and mechanical strength with the stationary seal ring 2. It is made of PTFE composite resin material.

  Thus, the rotary seal ring 5 is integrally connected to the connecting portion 4 d that is the tip of the bellows 4. The connection of both 4d and 5 is performed so that both 4d and 5 are integrated during the forming process of the bellows 4 and / or the rotary seal ring 5 or after the forming process of the bellows 4 and the rotary seal ring 5. In the integrated state, the boundary 15 between both 4d and 5 does not appear clearly. The outer diameter of the connecting portion 4d of the bellows 4 is the same as that of the base end portion of the rotary seal ring 5, but is slightly larger than the expandable portion 4a and the fixing portion 4b of the bellows 4.

  The spring retainer 6 has a cylindrical shape in which a distal end portion 6a is fitted to the connecting portion 4d and the rotary seal ring 5 of the bellows 4 and a base end portion 6b surrounds the expansion / contraction portion 4 of the bellows 4 and has a thermal expansion coefficient. It is made of a resin material equivalent to or similar to PTFE, which is a constituent material of the bellows 4. In this example, the composite resin material is composed of PTFE as a main component and is made of a PTFE composite resin material in which PTFE is filled with carbon. Note that the inner diameter of the distal end portion 6a of the spring retainer 6 is set so as to be tightly fitted to the connecting portion 4d of the bellows 4 and the rotary seal ring 5, but the inner diameter of the base end portion 6b is the distal end of the bellows 4. The outer diameter of the part 4d and the rotary seal ring 5 is set to be slightly larger than the outer diameter of the expansion / contraction part 4a of the bellows 4, and the spring retainer 6 is designed not to interfere with the expansion / contraction part 4a.

  On the distal end surface of the spring retainer 6, recesses 6 c are formed to engage with a plurality of annular projections 5 c that are formed on the distal end side outer circumferential surface of the rotary seal ring 5 at regular intervals in the circumferential direction. And the recess 6a engage with each other to prevent the relative rotation of the both 5 and 6. In addition, an annular step portion 6d formed at the boundary between the distal end portion 6a and the base end portion 6b at the inner peripheral portion of the spring retainer 6 is formed at the boundary between the expandable portion 4a and the connecting portion 4d at the outer peripheral portion of the bellows 4. Since the two step portions 4f and 6c are engaged with each other, a pressing biasing force by a spring member 7 to be described later surely acts on the bellows 4 via the spring retainer 6. Yes.

  The stopper ring 10 is provided with an appropriate number of drive pins 10a (only one is shown) and is engaged with a recess 6e formed on the rear end surface of the spring retainer 6 to thereby rotate the rotating shaft of the spring retainer 6. Relative rotation with respect to 2 is prevented while allowing axial movement thereof.

  The spring member 7 is composed of a plurality of coil springs (only one is shown) loaded at regular intervals in the circumferential direction between the spring retainer 6 and the stopper ring 10, and the rotary seal ring 5 is statically sealed. The spring retainer 10 (and the bellows 4) is urged so as to be brought into press contact with the ring 2. Each coil spring constituting the spring member 7 is loaded between the spring retainer 6 and the stopper ring 10 in a state of being inserted through the through hole 11 b formed in the tightening ring 11.

  In the bellows type mechanical seal configured as described above, a resin material having a thermal expansion coefficient equivalent to or close to that of PTFE, which is a constituent material of the bellows 4, the spring retainer 6 fitted to the bellows 4 even under high temperature conditions. Therefore, even when the bellows 4 is thermally expanded, a difference in thermal expansion amount does not occur or hardly occurs in the fitting portion between the two and 6, so that an excessive load (stress) is applied to the bellows 4. Does not work.

  Further, since the bellows 4 and the rotary seal ring 5 which is a different material from the bellows 4 are integrally connected in a state where the boundary 15 between the four and 5 does not appear clearly, the fluid in the in-machine region A (sealed) Of course, when the fluid is a liquid, even when it is a gas, the sealed fluid does not leak at all from the connecting portion 15 of both 4 and 5, and the sealed fluid can be well sealed. . Further, even when the sealed fluid is a gas (dry operation), the rotary sealing ring 5 is made of a PTFE composite resin material having excellent sliding characteristics with the ceramic stationary sealing ring 2, so that the sealing end face 2 a , 5a does not generate abnormal wear or heat, and can be in relative sliding contact with each other.

  Therefore, unlike the bellows-type mechanical seal described at the beginning, the bellows and the rotary seal ring are not formed as a single-piece structure of the same material, but the rotary seal ring 5 is compared with the constituent material of the bellows 4 (PTFE). Combined with the fact that it is made of a resin material with excellent sliding characteristics with the mating seal ring (stationary seal ring 2), it has a good mechanical seal function regardless of the properties of the fluid to be sealed even under high temperature conditions. Can be demonstrated.

  Note that the shaft seal device of the present invention is not limited to the above-described example, and can be appropriately improved and changed without departing from the basic principle of the present invention. For example, the bellows 4 and the rotary seal ring 5 may be molded separately and then adhesively connected with an adhesive, or may be engaged and connected using a pinching ring 16 as shown in FIG. It is also possible to keep it. That is, in the one shown in FIG. 2, an annular tongue 4 g is formed at the distal end 4 d of the bellows 4, and the annular protrusion 5 d that projects from the base end face of the rotary seal ring 5 and the clamping ring 16. The bellows 4 and the rotary seal ring are connected by pinching in the radial direction. The bellows-type mechanical seal shown in FIG. 2 has the same configuration as the bellows-type mechanical seal shown in FIG. 1 except for the connection structure between the bellows 4 and the rotary seal ring. The pinching ring 16 is a composite resin material containing PTFE as a main component and is made of PTFE filled with carbon fibers. By the way, in the bellows type mechanical seal shown in FIG. 2, when the fluid to be sealed is a gas, no matter how firmly the bellows 4 and the rotary seal ring 5 are connected, the leakage of the fluid to be sealed from the connecting portion is prevented. Since it cannot prevent, it is not preferable as what seals gas. In this respect, in the bellows type mechanical seal shown in FIG. 1, the bellows 4 and the rotary seal ring 5 are integrally connected. Therefore, even when the fluid to be sealed is liquid or gas, A good sealing function can be exhibited without causing any problems.

DESCRIPTION OF SYMBOLS 1 Seal case 2 Stationary sealing ring 2a Sealing end surface of stationary sealing ring 3 Rotating shaft 4 Bellows 4a Base end part (fixed part) of bellows
4b Middle part of bellows (expandable part)
4d Bellows tip (connecting part)
5 Rotating Seal Ring 5a Sealing End Face of Rotating Seal Ring 6 Spring Retainer 7 Spring Member A Sealed Fluid Area (In-machine Area)
B Non-sealed fluid area (external area)

Claims (3)

  A ceramic stationary seal ring fixed to the seal case, an axially expandable PTFE bellows whose base end is fitted and fixed to the rotary shaft, and a stationary seal ring connected to the tip of the bellows. Rotating seal ring made of hard resin material with excellent corrosion resistance and sliding characteristics with stationary seal ring, and relative rotation in the stationary seal ring direction and non-rotatable relative to the tip of the bellows and the rotary seal ring An engagement spring retainer, and a spring member disposed in an outer peripheral region of the bellows for pressing and urging the spring retainer in the direction of the stationary seal ring. Bellows type mechanical structure configured to seal the sealed fluid region, which is the inner peripheral region of the relative rotational sliding contact portion, and the non-sealed fluid region, which is the outer peripheral region, by the rotational sliding contact action. A Lumpur, corrosion resistance bellows type mechanical seal, characterized in that have configured spring retainer with a resin material having a thermal expansion coefficient bellows equal or approximate.   The corrosion-resistant bellows-type mechanical seal according to claim 1, wherein the rotary seal ring is made of a composite resin material mainly composed of PTFE.   The corrosion-resistant bellows-type mechanical seal according to claim 1 or 2, wherein the spring retainer is composed of a composite resin material mainly composed of PTFE.