JP5587081B2 - mechanical seal - Google Patents

Description

  The present invention relates to a mechanical seal, and in particular, a novel improvement for suppressing generation of noise from a sliding surface of a cylindrical bellows during rotation of a rotating shaft by holding the outer periphery of the cylindrical bellows by a vibration damping body. About.

Conventionally used mechanical seals of this type can be illustrated in FIG. 2 as commonly used configurations.
That is, in the configuration shown in FIG. 2, what is denoted by reference numeral 1 is a rotating shaft in which a shaft portion 1 a is rotatably disposed in a cylindrical fixed body 2, and is formed on the inner surface of the fixed body 2. The step 2a is provided with an annular fixed ring 2A through an O-ring 2b.
The peripheral edge of the fixed ring 2A is fixed on the fixed body 2 by a ring-shaped restraining body 3 attached to the fixed body 2 via bolts 2c.

One end 5a of a cylindrical bellows 5 is fixed to the outer peripheral surface 1b of the rotating shaft 1 through a split annular clamp 4 fixed by a screw 4a.
A sliding surface 5c of the other end 5b of the cylindrical bellows 5 slides on one surface 2d of the fixed ring 2A.
An annular retainer 6 is provided on the outer peripheral surface 5d of the cylindrical bellows 5. A plurality of recesses 6b are formed on one surface 6a side of the retainer 6, and a spring 7 is provided between the clamp 4 and the recess 6b. And pins 8 are provided.

2, the cylindrical bellows 5 is formed in a bellows shape by an elastic material such as PTFE or rubber, and can be deformed in an axial direction and a radial direction, and the pin 8 provided on the clamp 4. Thus, the retainer 6 rotates in synchronism with the rotating shaft 1.
The retainer 6 is urged by the spring 7 with respect to the clamp 4, and the fluid (not shown) can be sealed by pressing the sliding surface 5c of the cylindrical bellows 5 against the fixed ring 2A.

In the above-described configuration, when the rotating shaft 1 rotates, one end 5a of the cylindrical bellows 5 is fixed to the rotating shaft 1, and the sliding surface 5c of the other end 5b is in contact with the fixed ring 2A. Since it is only held by the spring 7 and the pin 8 with respect to the direction, it is cylindrical as shown by the arrow A in FIG. 3 due to the friction of the sliding surface 5 c and the centrifugal force of the cylindrical bellows 5 . A slit motion is generated in which the axial center of the bellows 5 moves conically.

In the above-described case, the cylindrical bellows 5 itself is elastically held with respect to the rotary shaft 1, so that a force to return to the shaft core works, and a sliding in the radial direction occurs on the sliding surface 5 c, A so-called squeal is generated.
The above-mentioned crushing motion causes fluid leakage from the sliding surface 5c, and the above-mentioned squeal becomes noise. In particular, this squeaking sound was noticeably generated in the case of a dry seal in which the sliding surface 5c is used without lubrication.

Further, as shown in FIG. 4, when the axial center of the cylindrical bellows 5 is swung in a cylindrical shape with respect to the rotary shaft 1, the cause and problem of the above-mentioned squeal are described in the case of FIG. It is the same.
Further, the sliding surface 5c does not wear much when it rotates concentrically with the rotary shaft 1, but when the cylindrical bellows 5 swings as shown in FIG. 4 , the sliding distance increases. Correspondingly, wear increased.

As a proposal for reducing the squealing noise as described above, there is a configuration of a self-excited vibration preventing mechanism for a mechanical seal of Patent Document 1, and in particular, as shown in FIG. An annular mass body 21 is provided on the seal ring 14 via an anti-vibration elastomer member 22, and the natural frequency of the damping system 20 composed of the annular mass body 21 and the anti-vibration elastomer member 22 is determined by the self-excited vibration of the seal ring 14. By setting the frequency range, the self-excited vibration of the seal ring 14 due to stick-slip on the sealing sliding surface S is absorbed, and the annular mass 21 and the vibration-proof elastomer member are arranged on the outer periphery of the seal ring 14. 22 is attached.

Further, as another proposal for reducing the squealing noise as described above, there is a configuration of a molded bellows type mechanical seal of Patent Document 2, and in particular, as shown in FIG. In a mechanical seal in which the rotating ring 26 and the stationary ring 6 carried on the machine casing 10 side are airtightly opposed to each other, a metal molding bellows 5 is interposed between the support cylinder 11 on the machine casing 10 side and the stationary ring 6. A cylindrical end 9a extending from the U-shaped flange 9 and its U-shaped flange 9 formed at the end of the molded bellows 5 are in close contact with the state where the U-shaped flange 9 is wound on both side surfaces of the support cylinder 11. A structure in which a groove-like space between the annular stepped portion 14b formed on the support cylinder 11 and located on the outer peripheral side is filled with a brazing agent or an adhesive, and the bellows 5 is made of a metal that is not easily deformed by twisting. And a rotating ring 6 to waste a separate spring for biasing the a configuration for preventing a squeal made to have a spring characteristic to the bellows 5 itself.

Utility Model Registration No. 3,008,177 Japanese Utility Model Publication 2-11659

Since the conventional mechanical seal was comprised as mentioned above, the following subjects existed.
That is, in the above-described conventional configuration shown in FIG. 5 , the vibration isolation design itself is difficult, and it is difficult to attach the structure by selling it as a retrofit to an already used mechanical seal.
Moreover, in the conventional structure of FIG. 6, since it was a metal bellows and the metal bellows was exposed outside, it was unsuitable for corrosion resistance use.
Moreover, since the structure of the suppressing member is not provided on the outer peripheral surface of the metal bellows, it is difficult to obtain the stability of the metal bellows.

The mechanical seal according to the present invention comprises a cylindrical bellows fixed to an outer peripheral surface of a rotary shaft via an annular clamp, and a fixed ring provided on a fixed body located on the outer peripheral side of the rotary shaft, and the cylinder by sliding surface of Jo bellows slides on the stationary ring, so as to seal the shaft portion of the rotary shaft, and a retainer provided on the outer peripheral surface of the cylindrical bellows, the outer periphery of the rotary shaft in main Kanikarushi Le with and a forming system isolator cup type to be fixed to a surface for holding the outer peripheral surface of the cylindrical bellows through the retainer, it is formed on the inner surface of the end portion of the damping body and between the groove and the retainer, it provided elastic body made of O-ring, before Symbol damping body, a plurality of first by being split along its axial direction, the second made of damping material piece, the upper portion of the front Symbol first damping body piece A screw inserted through a guide hole formed and having a hole direction in a direction orthogonal to the axial direction of the vibration damping body is disposed in the direction orthogonal to the axial direction of the vibration damping body. By screwing into the screw holes, the damping body pieces are fastened to form the damping body in the form of an integral cup, and the two damping bodies are the existing mechanical seals in use. In order to prevent the squealing sound, it can be attached later .

Since the mechanical seal according to the present invention is configured as described above, the following effects can be obtained.
That is, the cylindrical bellows fixed to the outer peripheral surface of the rotating shaft through a split annular clamp, and a fixed ring provided on a fixed body located on the outer peripheral side of the rotating shaft, the cylindrical shape A mechanical seal configured to seal a shaft portion of the rotating shaft by sliding a sliding surface of the bellows on the stationary ring, a retainer provided on an outer peripheral surface of the cylindrical bellows, and the rotating shaft e Bei and eggplant system isolator, a cup-type for holding an outer peripheral surface of the fixed to the outer peripheral surface the cylindrical bellows through said retainer, said damping body is divided into two parts along the axial direction the first consists of the second damping body piece, before Symbol screws inserted from the guide hole having a hole in the direction that is formed on the first damping body piece perpendicular to the axial direction of the damping body, Before being arranged in a direction orthogonal to the axial direction of the damping body By screwing into the screw holes of the second damping body piece, the damping body pieces are fastened to form the damping body that forms an integral cup shape, and the two damping bodies are existing in order to prevent squeaking of the mechanical seal in use, by which it can be mounted in retrofitting, squeaking sound due to the deformation of the cylindrical bellows is suppressed by the control isolator, and also can prevent reduction in vacuum , Keeps hermeticity.
Further, since an elastic body is provided between the vibration damping body and the retainer, the deformation of the cylindrical bellows can be elastically absorbed.
Further, the elastic body is made of an O-ring or a disk-shaped elastic body, so that sufficient elastic force and vibration damping force can be obtained.
Further, since the vibration damping body is made of a cup shape having a hole as a whole, it can be combined concentrically with the rotating shaft, and effective vibration damping can be performed.
In addition, the damping body includes first and second damping body pieces that are divided into a plurality of parts in the axial direction, and the damping body pieces are integrally connected by screws, so that a cylindrical damping body is formed. The vibrator can be manufactured at a lower cost and sold as a retrofit to an existing mechanical seal.

It is sectional drawing which shows the mechanical seal by this invention. It is sectional drawing which shows the conventional mechanical seal. It is sectional drawing which shows the state in which squeal occurred with the mechanical seal of FIG. It is sectional drawing which shows the other state in which squeal generate | occur | produced with the mechanical seal of FIG. It is sectional drawing of the structure of the patent document 1 which shows the conventional mechanical seal. It is sectional drawing of the structure of the patent document 2 which shows the conventional mechanical seal.

  An object of the present invention is to provide a mechanical seal in which the outer periphery of a cylindrical bellows is held by a damping body, thereby suppressing the generation of squealing noise on the sliding surface of the cylindrical bellows when the rotary shaft rotates. And

Hereinafter, preferred embodiments of the mechanical seal according to the present invention will be described with reference to the drawings.
In addition, the same code | symbol is used for the same or equivalent part as a prior art example, and is demonstrated.
1 is a rotating shaft in which a shaft portion 1a is rotatably held in a cylindrical fixed body 2, and an overall shape is formed on an outer peripheral surface 1b of the rotating shaft 1 through a hole 20a. The vibration damping body 20 having a cup shape is configured to be concentric with the rotating shaft 1. The vibration damping body 20 is fixed to the rotary shaft 1 with screws 21.
As the material of the vibration damping body 20, stainless steel having high corrosion resistance is preferable. However, when a transparent material such as polycarbonate resin and acrylic resin is used, the internal state of the vibration damping body 20 is well understood from the outside. Even when the cylindrical bellows 5 is damaged, direct fluid scattering to the outside can be prevented.

  One end 5a of the cylindrical bellows 5 is fixed to the outer peripheral surface 1b of the rotating shaft 1 and the inner position of the vibration damping body 20 by a split annular clamp 4 fastened by a screw 4a.

  The fixed ring 2A provided on the step portion 2a of the fixed body 2 is fixed by a ring-shaped holding body 3 fixed to the fixed body 2 via a pair of O-rings 2b by bolts 2c. On one surface 2d of 2A, a projecting sliding surface 5c formed on the other end 5b of the cylindrical bellows 5 is in contact so as to slide.

The outer peripheral surface 5d of the cylindrical bellows 5, a retainer 6 which forms an annular is provided in contact, on one surface 6a formed in the recess 6b of the retainer 6, scan pulling (Fig. 1, not shown as an elastic portion shown and have not placed in portions) and pin 8 is the position of the Sprint grayed urges the retainer 6 is positioned between the annular clamp 4 and the recess 6b to the fixed ring 2A side.

An O-ring 22 as an elastic body is provided in a groove 20c formed on the inner surface of the end 20b of the vibration damping body 20. The O-ring 22 abuts on the outer peripheral surface 6c of the retainer 6, and the cylinder The outer peripheral surface 5d of the shaped bellows 5 is held by the damping body 20 via the retainer 6 so as not to be deformed.
The material of the aforementioned O-ring 22 is selected depending on the use environment and the type of fluid, but is selected from perfluoroelastomer, NBR, silicon rubber, and the like.
Further, the retainer 6 is held concentrically with the rotary shaft 1 via the O-ring 22 on the damping body 20, and the compression rate (tightening) of the O-ring 22 is preferably 5 to 35%.
When the compression ratio is larger than the above range, the frictional force between the O-ring 22 and the outer peripheral surface 6c of the retainer 6 increases, and the outer peripheral surface 6c of the retainer 6 is less likely to slide with respect to the O-ring 22. The force for biasing the retainer 6 toward the stationary ring 2A by the spring 7 is insufficient, and leakage from the sliding surface 5c occurs.
Further, when the compression ratio is smaller than the above range, the force that the retainer 6 swings from the shaft center into a slit shape or a cylindrical shape due to the friction of the sliding surface 5 c or the centrifugal force of the cylindrical bellows 5 is caused by the O-ring 22. It becomes larger than the force that returns the bellows 5 to the center of rotation due to the elastic force, and the desired damping force cannot be obtained.

Further, the damping body 20 is divided into two along the axial direction and is composed of a pair of first and second damping body pieces 20A and 20B, and is formed on the upper portion 25 of the first damping body piece 20A. A screw 27 inserted from a guide hole 26 having a hole direction in a direction perpendicular to the axial direction E of the vibration body 20 is disposed in a direction perpendicular to the axial direction E of the vibration damping body 20, and the second vibration damping body. screw holes 2 7a to screwed has been the damping body piece 20A pieces 20B, are 20B fastening can be obtained damping body 20 of the cup-shaped piece shaped.
Therefore, since the vibration damping body 20 of FIG. 2 is two bodies, it can be attached later to prevent the noise of the existing mechanical seal in use, and the O-ring 22 is provided at one place in the circumferential direction. It is also possible to use a cut tube or a hollow tube.

Next, the present applicant conducted the following experiment in order to confirm the performance of the mechanical seal described above.
The following mechanical seal was attached to a 1000 liter glass-lined reaction can having a stirring blade having a shaft diameter of 55 mm.
Bellows material: PTFE
Material of sliding surface of bellows: PTFE + carbon fiber Material of stationary ring: 99% alumina
Mechanical seal rotation speed: 200 rpm
Sliding surface state: Dry (no water injection)
Pressure inside reaction can: 5 torr
Reactor temperature: 80 ° C
Since a squealing sound synchronized with the rotational speed was generated 40 hours after the start of rotation, the damping body 20 having the structure shown in FIG. 1 was attached.
O-ring material: NBR
O-ring wire diameter: φ5mm
Tighten the O-ring: 20%
The squealing stops immediately after the vibration damping body 20 is mounted, and since the squealing sound does not occur even after 500 hours have passed, the rotation is stopped, and leakage from the sliding surface is investigated from the degree of decrease in the degree of vacuum. Even after the lapse of time, the degree of vacuum did not change, and it was confirmed that hermeticity was secured.
Furthermore, even if the pressure in the reaction vessel was increased to 0.2 MPa and 500 hours passed, no squeal was generated.

  The mechanical seal according to the present invention can be used in a dry state or a glass-lined reaction can in addition to a general use environment.

DESCRIPTION OF SYMBOLS 1 Rotating shaft 1a Shaft part 1b Outer peripheral surface 2 Fixed body 2A Fixed ring 2a Step part 2b O ring 2c Bolt 2d One surface 3 Ring-shaped holding body 4 Annular clamp 4a Screw 5 Cylindrical bellows 5a One end 5b The other end 5c Sliding surface 5d Outer periphery Surface 6 Retainer 6a One surface 6b Recessed portion 6c Outer peripheral surface 8 Pin 20 Damping body 20A First damping body piece 20B Second damping body piece 20a Hole 20b End 20c Groove 22 O-ring (elastic body)
22a Disc-shaped elastic body 26 Guide hole 27 Screw 27a Screw hole E Axial direction

Claims (1)

A cylindrical bellows (5) fixed to the outer peripheral surface (1b) of the rotating shaft (1) via an annular clamp (4), and a fixed body (2) positioned on the outer peripheral side of the rotating shaft (1). The fixed ring (2A), and the sliding surface (5c) of the cylindrical bellows (5) slides on the fixed ring (2A). 1a) is sealed ,
A retainer (6) provided on the outer peripheral surface (5d) of the cylindrical bellows (5), and the cylindrical bellows fixed to the outer peripheral surface (1b) of the rotating shaft (1) via the retainer (6). and forming system the cup for holding the outer peripheral surface (5d) of (5) insulating member (20), the main Kanikarushi le equipped with,
Wherein between an inner surface in a groove formed in the end of the damping body (20) (20b) (20c) and said retainer (6), elastic body made of an O-ring (22) is provided, before serial damping body (20) has a plurality of first by being split along its axial direction (E), a second damping body pieces (20A, 20B) made of, before Symbol first system The screw (27) inserted from the guide hole (26) formed in the upper part (25) of the vibration piece (20A) and having a hole direction in a direction orthogonal to the axial direction (E) of the vibration damping body (20) is The vibration damping body (20) is screwed into a screw hole (27a) of the second vibration damping body piece (20B) disposed in a direction orthogonal to the axial direction (E) of the vibration damping body (20). The body pieces (20A, 20B) are fastened to form the vibration damping body (20) in the form of an integral cup, and the two vibration damping bodies (20) generate noise from the existing mechanical seal. to prevent, to the feature that you have a configuration that can be mounted in retrofit Rume Kanikarushiru.

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