JPS6162670A - Mechanical seal - Google Patents

Abstract

PURPOSE:To prevent thermal deformation of a seal ring by forming a static seal ring and a rotary seal ring by hard material such as WC cemented carbide in a simple substance structure without adopting a shrinkage fit structure using a metallic retainer. CONSTITUTION:A mechanical seal installed at an annular space portion 10 between a seal housing 8 and a rotary shaft 9 piercing through the housing includes a static seal ring 11 and a rotary seal ring 12, wherein SiC is used for one of the seal rings 11, 12, and WC cemented carbide is used for the other, the seal rings being respectively formed by a simple substance of these hard materials. Reinforcing metal rings 13, 14 for functioning the respective seal rings 11, 12 as reinforcement rings similarly to the conventional metal retainer are respectively fitted in the seal rings 11, 12 and fixed there.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mechanical seal suitable for use in a shaft seal of a turbo drill for drilling or a shaft seal of a transfer pump that handles high temperature and high pressure slurry liquid, and particularly relates to a mechanical seal suitable for use in a shaft seal of a turbo drill for drilling or a shaft seal of a transfer pump that handles high temperature and high pressure slurry liquid. Limit P
The V value (P is the load force acting on the seal end face, ■ is the circumferential speed at the seal end face) is a high temperature (approx.
Concerning mechanical seals used under sealing conditions at (℃).

By the way, the specific sealing conditions targeted by the mechanical seal of the present invention are as follows: (a) The sealing liquid is a highly heat-resistant oil, and the oil contains a slurry of silica sand or the like of up to 105%.

C, sealing pressure is 80-100Kgf/cm', 2, seal surface speed is about ILm/sec, e'! f. The sealing oil temperature is approximately 250°C, which is severe and exceeds the limits of conventional mechanical seals. Therefore, in order to satisfy these conditions, it is necessary to have the following technical requirements.

1) A sealing material with high heat resistance and no thermal deformation.
Or have fewer design structures.

11) The sealing material must have high slurry resistance.

l11) The load capacity ψ of the sole is high.

To explain this more specifically, a conventional mechanical seal is constructed as shown in FIG. 1 is the seal housing,
Reference numeral 2 denotes a rotating shaft inserted into the seal housing 1. A stationary seal ring 5 is mounted on the seal flange 3 of the seal housing 1 via a metal retainer 4, and a rotating seal ring 7 is mounted on the rotating shaft 2 via a metal retainer 6. The sealing end surfaces sa and 7a of both rings 5.7 are butted against each other. In this case, a respective metal retainer 4.6 is fixed to each seal ring 5.7 by shrink fitting.

However, when using this conventional type of shrink-fit structure between the seal rings 5, 7 and the metal retainer 4, 6, no matter how precisely this shrink-fit is performed, the seal rings are affected by the heat caused by the shrink-fit. The seal end faces 5a, 7 are thermally deformed due to the difference in linear expansion between the metal retainer and the metal retainer, and thermal deformation due to uneven temperature distribution.
a), so the above (1) is used as a mechanical seal.
) is difficult to satisfy. Moreover, as shown in FIG. 7, the centroid N of the metal retainer 6 and the centroid M of the seal ring 7 are eccentric by a distance in the direction of the axis of rotation, and the erectile position of the metal retainer 6 is correspondingly eccentric. The flatness deteriorates and the surface contact with the seal end faces 5a, 7a is impaired, and when used under the sealing conditions (a) to (e), the seal easily breaks.

In addition, in the sense of satisfying the condition (i) above, the sealing material for the slurry mixed liquid is 1% 50 to 10
If it exceeds 00pp-, soft materials such as carbon are unsuitable.
Only hard materials such as WC cemented carbide and SiC can be used, however, the PV value (damage limit value of sealing surface) between hard materials is extremely low, and in practical terms, the PV value (damage limit value of the sealing surface) is approximately 15% compared to carbon vs. SiC.
00, and in order to satisfy the sealing load (PV value) of approximately 1000KHf/crn'・ts/s (conditions (c) and (d) above), the load on the sealing part must be adjusted by design. We will have to increase the capacity by 7.

In view of the above points, the present invention aims to provide a mechanical seal that satisfies the conditions (1) to (ii) above.

In order to achieve such an object, the mechanical seal of the present invention has a seal housing and a rotating shaft inserted through the shaft sealing portions of the seal housing and the rotating shaft inserted therein.
A stationary seal ring and a rotating seal ring are provided that are in contact with each other. Both seal rings are made of a single piece of hard material such as WC cemented carbide or SiC'i4, and a reinforcing metal ring is press-fitted onto the outer surface of each seal ring to form a rotating seal. In the ring, a drive collar that rotates integrally with the rotating shaft is engaged with the reinforcing metal ring so as to transmit rotational torque, and one of the sealing end faces of the seal ring is provided with a step notch for upward improvement. It is in.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

In FIG. 1, a mechanical seal installed in an annular space 10 between a seal housing 8 and a rotary member 9 inserted therein includes a stationary seal ring 11 and a rotating seal ring 1.
SiC is used for one of these seal rings 11 and 12, and WC cemented carbide is used for the other, and each seal ring is constituted by a single piece of these hard materials. Then, reinforcing metals 1i13 and 14, which serve as reinforcements for each seal ring 11.12 in the same manner as a conventional metal retainer, are press-fitted and fixed onto the seal rings 11.12, respectively. In this case, care is taken so that the centroid M of the seal ring 11.12 and the centroid N of the reinforcing metal ring 13.14 match as shown in FIG.

Then, the stationary seal ring 11 is fitted into the seal flange 15 of the seal housing 8, and the stationary seal ring 11 comes to rest by inserting and engaging the fixing bolt 26 screwed into the seal flange 15 into the recessed hole 27 of the reinforcing metal ring 13. The rotation of the seal ring 11 is prevented, and an O-ring 16 is interposed between the back surface 11a of the static upper seal ring 11 and the inner end surface 15a of the seal flange opposite thereto.
Due to the well-known axial thrust, the O-ring 16 is
5a, and is configured to exert a predetermined sealing force.

On the other hand, the rotary seal ring 12 is fitted onto the shaft with an O ring 17 interposed between it and the rotary Ihl+9, and the drive collar 18 is externally fitted to the one-turn seal ring 128 and the reinforcing metal ring 14. At the same time, one spring retainer and drive collar 18 are attached to the rotating shaft 9.
are connected to be movable relative to each other by a drive pin 20 in the first section, and a compression spring 21 is interposed between the two 18 and 19, so that the stationary seal ring 11 and the stationary seal ring 2 are Seal end surface 11a.

12a and are brought into face-to-face contact with each other in sliding contact.

The drive collar 18 and the reinforcing metal ring 14 are engaged with each other so that rotational torque can be transmitted, and therefore, as is clear from FIG. An engagement groove 22 is formed, into which a rotation preventing rib 23 swelled on the inner circumferential surface of the drive collar 18 is engaged.

Furthermore, as shown in FIGS. 3 and 4, at the seal end surface 11a of the stationary seal ring 11 (this may be a rotating seal ring), a ridge 24 on the high pressure sealing oil side
A lubrication improving step 25 is formed by cutting off a small amount at a plurality of locations in the circumferential direction. This step 25, for example, t=1~2m+a,b/
l ~2~4, h=0.5~1.5mm, number of steps 6~8 under forming conditions, 80~100 Kz
This forcefully causes a slight oil leakage of about 5 to 50 cc/Hr at a hydraulic pressure of f/cm' to occur on the sealing surface.

According to the above configuration, each of the stationary seal ring 11 and the rotating seal ring 12 does not have a shrink-fit structure of a metal retainer as in the past, but each of the &
! j! Since it is made of a single piece of solid material, there is no thermal effect due to the shrink fitting, and no thermal deformation occurs. A high-precision sealing surface is maintained in close contact with the

The strength of the seal rings 11, 12 is also increased by the reinforced metal rings 13, 13, which are press-fitted into these rings in place of conventional metal retainers.
14, but even if the chain ring 13.14 expands by PI% due to the high temperature of the sealing oil, the centroids N and M of the seal ring and the reinforcing metal ring will remain the same as shown in Figure 5. Since they almost match, the amount of thermal deformation that affects the seal ring is suppressed, and the weight of the reinforcing metal rings i3, 14 can be small, so that the flatness of the sealing surface as a whole can be maintained. FIG. 6 is a graph showing a comparison of flatness between the conventional type a and the present invention, and shows that the conventional type a has a deviation of 10 to 20 w, but the present invention has a deviation of 0.2 to 0.
It can be seen that it is smaller at 67zm. Naturally, sealing performance such as leakage amount and local burnout is determined by the flatness of the sealing surface, so the difference in effectiveness between the conventional type and the present invention is obvious. Note that another reinforcing metal ring may be press-fitted inside each seal ring 11, 12 to further improve the strength.

Furthermore, the aforementioned lubrication enhancement step 25 forces a slight oil leak to the sealing surface, thereby increasing the PV limit due to the hard material of the sealing rings 11, 12.

As can be easily understood from the above description, according to the present invention, the stationary seal ring and the rotating seal ring are made of a hard material such as WC cemented carbide or SiC without employing a shrink-fit structure using a metal retainer. Because it has a single-piece structure, it is possible to prevent thermal deformation of the seal ring due to conventional shrink fitting, and the seal end surfaces of both seal rings can be brought into good surface contact with each other to prevent seal breakage. Since the ring is fixed with a metal reinforcing ring fitted over the ring, this metal reinforcing ring can strengthen the brittleness of the seal ring due to its single structure. Care can be taken to ensure that the centers are almost aligned in the axial direction of the rotating shaft, and even if thermal changes occur, the effect on the seal ring can be eliminated.Furthermore, the weight of the metal reinforcing ring can be small, so the sealing surface can be High flatness can be maintained.

Furthermore, by forming a step for improving lubrication on the seal end face of either the stationary seal ring or the rotating seal ring, a small amount of oil leaks between the seal end faces through this step, and the PV value increases. Although the PV limit between hard materials is originally low, this can be compensated for by the above steps and the load capacity of the seal can be greatly improved.

Therefore, according to the present invention, (a) to (e) mentioned at the beginning
We have now been able to provide a mechanical seal that satisfies the harsh sealing conditions.

[Brief explanation of the drawing]

Figures 1 to 3 show one embodiment of the present invention, where Figure 1 is a sectional view of a mechanical seal, and Figure 2 is a cross-sectional view of a mechanical seal.
■ Line cut diagram, Figure 3 is an enlarged view of the sealing surface part, Figure 4 is a seal end view of the stationary seal ring, Figure 5 is a diagram of the centroid relationship between the seal ring and the reinforcing metal ring, and Figure 6 is the conventional type. FIG. 7 is a cross-sectional view of a conventional mechanical seal, showing the difference in the flatness of the seal surface between the present invention and the present invention. 8... Seal ring 9... Rotating shaft 11... Stationary seal ring 1z... Rotating seal ring 13.14... Reinforced metal ring 18... Drive collar 25... Lubrication improvement step patent application Person [] Hon Biller Kogyo Co., Ltd. Komatsu Manufacturing Co., Ltd. Representative Person Patent Attorney Takashi Suzue - Figure 1 Figure 2 Figure 4 Figure 3 Figure 25 Figure 5 IJ Figure 6 Figure 7 Procedural Amendment Document Patent Application Akira No. 59-183224 No. 2 Name of the invention Mechanical seal 3゜ Relationship between the person making the amendment and the tenancy Patent applicant U Hon Pillar Industries Co., Ltd. Komatsu Ltd. 4th generation JJJ Address 8-1 Kamiyama-cho, Kita-ku, Osaka Tatsumi Umeda Bill Spontaneous 6 Column for detailed explanation of the invention in the specification subject to amendment (1) Specification fJ'LJ2 Q p rMA on line 9
The description of "X105J" is corrected to "rMAX I 0%". (2) In the same page 8, line 6, "05~1.5■J" is written as ro, l-3mm (h is the seal end face of the mechanical seal polished and lapped after use. It is preferable to set it to around 1 mm (maximum 3III11) in consideration of the machining allowance when used. This has the advantage of saving the effort of re-machining step 25." (3) The description of "hydraulic pressure" on page 8, line 7 is corrected to "hydraulic time J."

Claims (1)

[Claims] (1) A stationary seal ring and a rotating seal ring are provided in the shaft sealing portion of the seal housing and the rotating shaft inserted therein, and the sealing end faces of each other are brought into butt and sliding contact, and both seal rings are made of WC cemented carbide or In addition to having a unitary structure made of a hard material such as SiC, a reinforcing metal ring is press-fitted onto the outer surface of each seal ring, and in the case of a rotating seal ring, a drive collar that rotates integrally with the rotating shaft is rotated by the reinforcing metal ring. A mechanical seal that engages to transmit torque and has a step for improving lubrication formed on the end face of one of the seal rings.