JP2002195420A - Deformation control method for rotary ring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably prevent problems such as an excessive leakage of a sealed object and the contact of an inner peripheral section with an opposite side even when the effect of a thermal deformation against a dynamic pressure action becomes relatively large. SOLUTION: The seal end face 2 of a rotary ring 1 is rotated relative to the seal end face 21 of a fixed ring 20 via an object to form a noncontact mechanical seal. When the effect of the thermal deformation against the dynamic pressure action becomes relatively large, the rotary ring 1 is not practically deformed by centrifugal force. At the high-speed rotation in the second stage, the rotary ring 1 tends to be deformed mainly by heat and centrifugal force, however the deformation of the rotary ring 1 by heat is canceled by the deformation by centrifugal force in this deformation control method for the rotary ring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of controlling deformation of a rotating ring, and more particularly to a method of controlling deformation of a rotating ring used for an end face type non-contact seal for high-speed gas.

[0002]

2. Description of the Related Art A rotating ring used for an end face type non-contact seal for high-speed gas is mainly made of a hard ceramic material such as tungsten carbide, silicon carbide, silicon nitride, etc., in order to simplify processing and analysis. A rectangular shape or a symmetrical cross-sectional shape close to the rectangle is formed (see FIG. 8).

[0003] The rotating ring 31 having such a structure is used as, for example, a rotating ring 31 of an end face type non-contact mechanical seal for high-speed gas, and a mechanical seal is attached to a seal portion to rotate a rotating body (not shown). Then, the rotating ring 31 rotates integrally with the rotating body, and the seal end face 32 of the rotating ring 31 is rotated.
And a seal end face of a stationary ring (not shown) slide with each other via an object to be sealed (inert gas, dangerous gas, air, steam, and the like, the same applies hereinafter), and the sealing portion is sealed. .

In this case, the pressure of the object to be sealed and the rotating ring 3
The opening force and the closing force acting between the two seal end faces are balanced by cooperation with the urging force of an urging member (not shown) that presses the one or the fixed ring in the counterpart direction. Are held at intervals of about several microns with the object to be sealed interposed therebetween.

Since the rotating ring 31 having the above-described configuration is formed in a rectangular shape or a symmetrical cross-sectional shape close to a rectangular shape, deformation caused by centrifugal force occurs mainly in the radial direction even when the rotating ring 31 is rotated at a high speed. Very little will occur in the direction. Therefore, the deformation components of the two rings that affect the pressure distribution between the two seal end faces can be determined by considering pressure and heat.

In this case, the deformation due to the pressure is caused by adjusting the cross-sectional shapes of the buoyancy generating means 34, the rotary ring 31 and the fixed ring, which form a dynamic pressure groove, a static pressure groove, a taper portion, a step portion, etc. on the seal end face 32. Can be arbitrarily controlled by
Of course, deformation due to heat cannot be completely eliminated, but it is also difficult to keep it negligible as long as it is a high-speed seal.

[0007] Heat is generated from each surface of the rotating component.
Since the highest density is generated from the seal end face 32 in contact with the film of the object to be sealed, a temperature gradient is generated inside the rotary ring 31 on the seal end face 32 side and low on the opposite end face 33 side. The end face 32 has an inner high deformation (convex deformation) in which the inner peripheral side approaches.
n).

In many cases, the inner high deformation increases the opening force generated between both seal end faces and increases the amount of leakage of the object to be sealed from between the two seal end faces. On the contrary, the dynamic pressure grooves are located. In some cases, the distance closer to the outer periphery is widened, the dynamic pressure action is weakened, and the risk of the inner periphery contacting the other side may increase.

In the dynamic pressure type non-contact seal, the higher the number of revolutions, the higher the dynamic pressure action, the wider the gap between both seal end faces,
There is a basic property that a stable film of the object to be sealed is formed between both seal end faces, but if the influence of heat deformation relative to the dynamic pressure action becomes relatively large, excessive Problems such as leakage and contact of the inner peripheral portion with the other side occur.

Here, the case where the influence of thermal deformation becomes relatively large means that the inner peripheral portion has a small inclination angle even if the width of the seal end face 32, that is, the dimension obtained by subtracting the inner diameter from the outer diameter is large. This is the case where the risk of contact with the other party increases or where the thermal deformation itself is large due to the characteristics of the material.

According to the present invention, even when the influence of deformation due to heat becomes relatively large with respect to the dynamic pressure action, it is possible to prevent excessive leakage of the object to be sealed or contact of the inner peripheral portion with the counterpart. It is an object of the present invention to provide a method for controlling deformation of a rotating ring, which can surely prevent the problem.

[0012]

Means for Solving the Problems An example of the solution of the present invention is a method for controlling deformation of a rotating ring described in each claim.

[0013]

According to one embodiment of the present invention, a rotating ring has a seal end face orthogonal to the axis at one end in the axial direction and an opposite end face orthogonal to the axis at the other end.
Further, the seal end face slides on the seal end face of the stationary ring via the object to be sealed.

A means having a sectional shape such that the center of gravity is located on the opposite end face side from the center of the plate thickness is employed.

Also, a step, a concave portion, an inclined portion, and the like are formed on the outer peripheral portion to form an asymmetrical cross-sectional shape, and the center of gravity is positioned on the end face side opposite to the center of the plate thickness. .

Further, a means made of a metal alone, a resin alone, or a material obtained by curing at least a part of the surface of a metal material or a resin material by means of coating, plating, thermal spraying, vapor deposition, nitriding or the like is employed. .

Further, according to another embodiment of the present invention, the mechanical seal is attached to the rotating body and rotates integrally with the rotating body, and has a seal end face at one end in the axial direction orthogonal to the axis. An annular rotating ring having an opposite end surface perpendicular to the axis at one end, and a seal end surface attached to the fixed body and having an axial end at one end in the axial direction, wherein the seal end surface is sealed with the seal end surface of the rotary ring. An annular stationary ring that slides through the object, and a biasing member that presses the rotating ring or the stationary ring in the opposite direction are provided, and the pressure of the sealing object and the biasing force of the biasing member are reduced. By balancing the closing force (opening force) and the opening force (opening force) in cooperation, a predetermined distance is maintained between the seal end face of the rotating ring and the seal end face of the fixed ring. It is a mechanical seal that is way.

Means is employed in which the rotating ring is formed in a sectional shape such that the center of gravity is located on the opposite end face side from the center of the plate thickness.

Further, the rotating ring is formed in a laterally asymmetric cross-sectional shape by forming a step portion, a concave portion, an inclined portion, etc. on the outer peripheral portion, and the center of gravity is located on the end face side opposite to the center of the plate thickness. Is adopted. The rotating ring is composed of a metal simple substance
Means made of a resin alone or a material obtained by curing at least a part of the surface of a metal material or a resin material by means of coating, plating, thermal spraying, vapor deposition, nitriding or the like is employed.

According to the present invention, a large centrifugal force can be applied to the opposite end surface side at the time of high-speed rotation such as 19500 rpm, and the centrifugal force can cause the outer end surface to be deformed at a high level. Therefore, the inner high deformation caused by the heat generated at the seal end face can be canceled by the outer high deformation.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows one embodiment of a rotating ring according to the present invention. That is, the rotating ring 1
It is formed annularly from a hard ceramic material such as tungsten carbide, silicon carbide, silicon nitride, and the like. One end in the axial direction is formed on a seal end surface 2 orthogonal to the axis, and the other end is an opposite end surface orthogonal to the axial run. 3 is formed.

A buoyancy generating means 4 is provided on the seal end face 2 of the rotating ring 1 by a dynamic pressure groove, a static pressure groove, a tapered portion, a step, etc., and the buoyancy generating means 4 fixes a fixed ring (not shown).
Is maintained at a predetermined distance from the seal end face.

The right half of the outer peripheral surface of the rotary ring 1 is cut out at a predetermined depth over the entire circumference, and an annular step 5 is formed at that portion. By forming such a stepped portion 5 on the outer peripheral surface, the cross-sectional shape becomes asymmetrical left and right, and the position of the center of gravity is set at a position shifted by a predetermined dimension in the direction of the end surface 3 opposite to the center of the plate thickness. Become.

Reference numeral 7 denotes a notch for preventing rotation.
It is provided at at least one location on the outer peripheral surface.

FIG. 2 shows an embodiment of an end face type non-contact mechanical seal 10 for high-pressure gas using the rotating ring 1 shown in FIG. This mechanical seal 10
Is a metal retainer 11 mounted on a rotating shaft 25 as a rotating body, the above-described rotating ring 1 mounted on the outer peripheral side of the retainer 11, and a metal cover 16 mounted on the fixed body 26 side. A fixed ring 20 made of carbon mounted on the inner peripheral side of the cover 16, and an urging member mounted between the fixed ring 20 and the cover 16 to press the fixed ring 20 in the direction of the rotating ring 1. The compression spring 23 is provided.

The retainer 11 includes a cylindrical main body 12 fitted to the rotating shaft 25, a flange 13 formed integrally with one end of the main body 12 in the axial direction and projecting radially outward in a ring shape. An annular groove 14 is formed at one end face in the axial direction of the flange portion 13 at a predetermined depth, and the rotating ring 1 is inserted into the groove 14 through a centering member, that is, a centering leaf spring 15. It is designed to be attached.

A non-rotating pin (not shown) is mounted between the non-rotating notch 7 of the rotary ring 1 and the retainer 11, and the rotary ring 1 is attached to the retainer 11 by the non-rotating pin. It is possible to prevent relative rotation.

The cover 16 is formed in the shape of a disk, and has a hole 17 at the center thereof for passing a rotating shaft 25 penetrating in the axial direction. An annular groove 18 having a predetermined depth is formed in the end face,
A fixed ring 20, which will be described later, is mounted in the groove 18 so as to be movable in the axial rotation direction.

The stationary ring 20 has an annular shape formed of carbon. One end in the axial direction is formed on a seal end surface 21 orthogonal to the axis, and the other end is formed on an opposite end surface 22 orthogonal to the axis. ing.

A compression spring 23 is mounted between the opposite end surface 22 of the fixed ring 20 and the bottom surface of the groove 18 of the cover 16 at predetermined intervals in the circumferential direction. The fixed ring 20 is pressed in the direction of the rotating ring 1.

When the mechanical seal 10 constructed as described above is mounted between the fixed body 26 and the rotating body 25 (rotary shaft 25), and the rotating shaft 25 is rotated, the rotating shaft 25 is rotated.
The retainer 11 and the rotating ring 1 rotate integrally with the rotating ring 1
The seal end face 2 of the fixed ring 20 and the seal end face 21 of the stationary ring 20 slide with each other via an object to be sealed (inert gas, dangerous gas, air, steam, etc.) therebetween, and the fixed body 26 and the rotating body 25, that is, the sealing portion is sealed.

In this case, the rotating ring 1 is formed in an asymmetrical cross-sectional shape, and the center of gravity is shifted from the center of the plate thickness to the opposite end surface 3.
As a result, a large centrifugal force can be applied to the opposite end face 3 during high-speed rotation (especially during the second-stage high-speed rotation described later). Outer high deformation in which the outer peripheral side of the seal end face 2 approaches the seal end face 2 (concave deforma)
) can be caused, and the inner high deformation caused by heat generated in the seal end face 2 due to the outer high deformation can be canceled.

Therefore, even if the rotating ring 1 is deformed by heat, the opening force (opening force) and the closing force (closing force) between the two seal end faces 2 and 21 can be balanced, so that the two seal end faces 2 can be balanced. , 21 can be stably formed.
As a result, the opening force (opening force) increases and the amount of leakage of the object to be sealed increases, and the distance between the seal end faces 2 and 21 where the buoyancy generating means 4 such as a dynamic pressure groove is located becomes large. As a result, the dynamic pressure action is weakened, and the risk that the inner peripheral portion of the seal end face 2 of the rotating ring 1 comes into contact with the counterpart is not increased.

In the illustrated embodiment, the inner high deformation due to heat is canceled by the outer deformation due to centrifugal force, but it is also possible in principle to cancel the inner high deformation due to heat by the outer deformation due to pressure. . However, with a seal in which external deformation due to pressure is promoted, a sufficient opening force (opening force) cannot be obtained at low speed or at rest, and the seal may not function as a non-contact seal.

Here, the relationship between deformation due to pressure, heat, and centrifugal force will be described in detail.

The heat generated at the end face of the seal is predominantly due to the viscous shearing of the object to be sealed in the minute gap. According to the formula, the torque is proportional to the rotation speed, and the heat generation is proportional to the square of the rotation speed. Therefore, the resulting temperature gradient and thermal deformation are also proportional to the square of the rotational speed. On the other hand, the deformation of the rotating disk or the rotating cylinder due to the centrifugal force is also proportional to the square of the rotation speed. As described above, the thermal deformation and the deformation due to the centrifugal force increase at almost the same ratio. Therefore, by positively utilizing the deformation due to the centrifugal force, the adverse effect due to the thermal deformation over a wide rotation speed range is obtained. Control of deformation that does not occur can be performed.

The deformation due to the pressure, the deformation due to the heat, and the deformation due to the centrifugal force can be respectively calculated by the finite element method or the like. However, in an actual product, the leakage amount may deviate from the expected value. When the leakage amount at the time of stoppage is as expected and the leakage amount at the time of rotation is different from the expectation, the amount of deformation due to the centrifugal force can be adjusted by additionally processing the rotating ring 1. For example, as shown in FIG. 3, the outer peripheral surface is additionally processed from the state shown in FIG. 1 to reduce the depth of the step, or as shown in FIG. 4, a chamfer is provided on the outer peripheral portion on the opposite end surface 3 side. Thereby, outer deformation due to centrifugal force can be reduced. FIG.
As shown in (2), by additionally processing a portion close to the seal end face 2, it is possible to increase the outer height deformation due to the centrifugal force.

In the rotating ring, the outer high deformation due to the centrifugal force occurs only to a negligible degree at the time of ordinary high-speed rotation (hereinafter referred to as the first-stage high-speed rotation) which has been generally performed. At a high-speed rotation (for example, 19500 rpm) (hereinafter referred to as a second-stage high-speed rotation), outer high deformation due to centrifugal force becomes remarkable.

The present invention is applicable to such a high-speed rotation (in particular,
By actively utilizing the deformation caused by the centrifugal force of the rotating ring that occurs during the second stage of high-speed rotation such as 9500 rpm), an excessive amount of leakage of the object to be sealed and a counterpart of the seal end face over a wide range of use conditions. This prevents damage caused by contact with the side. As a result, the end face type non-contact seal removes one of the obstacles in the process of increasing the size, increasing the speed, and increasing the pressure. In addition, not only non-contact seals, but also ceramics and carbon have been used as sealing rings in mechanical seals,
When such a brittle material is used as a rotating ring of a high-speed seal,
The rotating ring may be damaged due to any unexpected accident, and the rotating ring may be damaged by the accident. Attempts to prevent damage by forming the rotating ring from a ductile material such as a metal have been embodied, but one problem to be overcome when using a metal is the magnitude of thermal deformation. In many cases, metals have lower thermal conductivity and higher coefficient of thermal expansion than ceramics, so that the inner high deformation due to heat is large. However, according to the present invention, deformation due to heat can be offset by deformation due to centrifugal force, which contributes to the practical use of a metal rotating ring. If the metal surface does not have the tribological properties required for the seal end face, a surface treatment such as coating is applied, but the effect of the present invention is applied as it is.

FIG. 6 shows a deformed state of the rotating ring and the fixed ring in one specific embodiment of the mechanical seal according to the present invention, and FIG. 7 shows a deformed state of the rotating ring and the fixed ring in the mechanical seal of the reference example. . These have a shaft diameter of 76m
The deformation state of the rotating ring 1 and the fixed ring 20 of the non-contact mechanical seal for gas for m is obtained by calculation.

The rotary ring 1 is made of martensitic stainless steel and has a ceramic film formed only on the seal end face 2.
The fixed ring 20 is made of carbon graphite. The thickness of the rotary ring 1 is 9 mm, and in the reference example of FIG. 7, the centroid of the cross section is located at 4.50 mm from the seal end face 2. FIG.
The seal of the reference example was gauged with nitrogen gas at a pressure of 3.43 MPa.
, And the actual measured value of the nitrogen gas leakage amount when rotating at 19500 rpm (the second stage high-speed rotation speed) is 89N1.
/ Min. In the embodiment of the present invention in which the outer peripheral portion of the rotating ring 1 is additionally processed (FIG. 6), the centroid 6 of the cross section moves to 4.59 mm from the seal end face 2 and is located closer to the opposite end face 3 than the center of the thickness. Approaching the. The fixed ring 20 is the same as in FIG. When the seal of the embodiment of the present invention shown in FIG. 6 is pressurized to a gauge pressure of 3.43 MPa with nitrogen gas and rotated at 19500 rpm (high-speed rotation speed in the second stage), the actual measured value of nitrogen gas leakage is 45 N1 / min. there were. Although no abnormality such as contact of the seal end face 2 occurred before and after the additional processing, the leakage amount was reduced by about half from 89 N1 / min to 45 N1 / min by the additional processing. In this way, by intentionally shifting the position of the centroid 6 of the cross section, particularly at 19500 rpm
It was found that the characteristics of the seal could be improved during the second stage of high speed rotation, such as m.

[0043]

According to the present invention having the above-described structure, the second rotation can be achieved, particularly at 19500 rpm.
At the stage of high-speed rotation, a large centrifugal force can be applied to the opposite end face side, and this centrifugal force can cause an outer high deformation in which the outer peripheral side of the seal end face approaches the seal end face. Therefore, even if an inner height deformation in which the inner peripheral side approaches the seal end face due to the deformation due to heat is generated, the inner height deformation can be canceled by the outer height deformation due to the centrifugal force. As a result, the amount of leakage of the object to be sealed from between the seal end faces increases, and the distance between the seal end faces near the outer periphery is widened, and the risk that the inner peripheral portion of the seal end face comes into contact with the mating side increases. Can be prevented, a stable film of the object to be sealed can be formed between the seal end faces, and the sealed portion can be stably sealed.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a method for controlling deformation of a rotating ring according to the present invention.

FIG. 2 is a cross-sectional view showing one embodiment of a method for controlling deformation of a rotating ring according to the present invention.

FIG. 3 is a cross-sectional view showing another embodiment of a method for controlling deformation of a rotating ring.

FIG. 4 is a cross-sectional view showing another embodiment of a method for controlling deformation of a rotating ring.

FIG. 5 is a cross-sectional view showing another embodiment of a method for controlling deformation of a rotating ring.

FIG. 6 is a cross-sectional view showing a deformed state of a rotating ring and a stationary ring in an embodiment of the method of controlling deformation of a rotating ring according to the present invention.

FIG. 7 is a cross-sectional view showing a deformed state of a rotating ring and a fixed ring in a reference example.

FIG. 8 is a sectional view showing an example of a conventional rotating ring.

[Explanation of symbols]

 1, 31 ... Rotating ring 2, 21, 32 ... Seal end face 3, 22, 33 ... Opposite end face 4, 34 ... Buoyancy generating means 5 ... Step section 6 ... Centroid of section 7 ... Non-rotating Notch 10 Mechanical seal 11 Retainer 12 Body 13 Flange 14, 18 Groove 15 Alignment member (leaf spring for alignment) 16 Cover 17 Hole 20 ... fixed ring 23 ... urging member (compression spring) 25 ... rotating body (rotating shaft) 26 ... fixed body

Claims (4)

[Claims] 1. A seal end face (2) of a rotating ring (1) is fixed to a seal end face (2) of a stationary ring (20) via an object to be sealed.
The rotating ring (1) is deformed by pressure, heat and centrifugal force in a state of rotating with respect to 1) and forming a non-contact type mechanical seal, but is deformed by heat against dynamic pressure action. When the influence becomes relatively large, the rotating ring (1) tends to be deformed mainly by heat and centrifugal force,
A deformation control method for a rotating ring, wherein the deformation of the rotating ring (1) due to heat is canceled by the deformation due to centrifugal force. 2. When the deformation due to heat becomes relatively large with respect to the dynamic pressure action, the inner ring of the rotation ring (1) is deformed by heat generated by the rotation ring (1) and the object to be sealed. , And at the same time, due to the centrifugal force generated in the rotating ring (1), an outer high deformation of the rotating ring (1) tends to occur,
2. The method according to claim 1, wherein the inner deformation caused by heat is canceled by the outer deformation caused by centrifugal force. 3. The method for controlling deformation of a rotating ring according to claim 1, wherein the metal is martensitic stainless steel. 4. The method for controlling deformation of a rotating ring according to claim 1, wherein a coating is provided on a seal end face (2) of the rotating ring (1).