GB2051974A

GB2051974A - Stuffing Box

Info

Publication number: GB2051974A
Application number: GB8015744A
Authority: GB
Original assignee: LIST IND VERFAHRENSTECH
Current assignee: LIST IND VERFAHRENSTECH
Priority date: 1979-06-15
Filing date: 1980-05-13
Publication date: 1981-01-21
Also published as: CH637741A5; IT8022091A0; DE3018658A1; JPS56105155A; FR2459414A1; IT1131513B

Abstract

A stuffing box has packing material (5) pressed against a shaft (1) and within a sleeve (22) like part of a stuffing box member 2. Between the member 2 and the casing 8,9,17 is a sealing member (6) which allows radial movement of the member. The member is connected to the casing 8,9,17 via bolts (11) acting generally axially but allowing such radial movement. The parts 8,9,17 of the casing are connected by bolts 10. <IMAGE>

Description

SPECIFICATION Stuffing Box The invention relates to a stuffing box for sealing a shaft bushing in a casing by pressing a packing material against the shaft.

When sealing shaft bushings by means of stuffing boxes, shaft deflections and tilting, or eccentric movements of the shaft, create large radial pressures on the packing material, so that the packing material is subject to increased wear and must be frequently changed.

Such expensive radial loading of the stuffing box occurs particularly with machines having a high expenditure of energy, e.g. when processing plastics and viscous substances.

According to the present invention there is provided a stuffing box for sealing a shaft bushing in a casing by pressing a packing material against the shaft, the packing material being enclosed with a sleeve-like part of a stuffing box member surrounding the shaft and being axially compressed by a gland, wherein an elastic sealing member is located between the stuffing box member and the casing, which sealing member allows radial movement of the stuffing box member, and including generally axially extending connecting members for connecting the stuffing box member with the casing.

The invention reduces the problems of such overloading of the packing material due to radial or tumbling movements of the shaft, without thereby impairing the operation of the stuffing box and/or its sealing action.

Due to the radial, elastic mounting of the stuffing box member, there can be no tilting or tumbling movements of the shaft, relative thereto, so that overloading of the packing material is reduced or prevented. The radial deflection of the stuffing box is made possible by the mounting support for the stuffing box member being retained in the axial direction, and the use of the elastic intermediate member. Due to this arrangement, the stuffing box can be secured on the casing and absorb axial forces occurring on the outside of the stuffing box due to the pressure difference within the casing. However, in order to still permit a limited mobility of the stuffing box member in the radial direction, said member preferably engages the casing via a slip ring.

An example of the invention is now described with reference to the sole accompanying drawing which is a cross sectional view of a stuffing box.

A shaft 1 extends through a stuffing box memzer 2, a gland 3 which is partly inserted into the latter a stationary mounting ring 4 and stuffing box packing 5 into a casing. Peripherally distributed pressure screws 19, of which one is indicated by the dot-dash line in the drawing, conneit a fla ge 20 of gland 3 to a flange member 21 of the stusfing box member 2. As a result, the packing material 5, which surrounds the shaft can be axially compressed against the mounting ring 4, and by reason of its deformation it presses radially onto the periphery of shaft 1.

Outwards of the packing material, a sleeve-like receiving member 22 of stuffing box member 2 engages a rubber ring 6 enclosed between a cross-sectionally angular chamber ring 8 and a mounting flange 9. Chamber ring 8 and mounting flange 9 are rigidly fixed to the casing wall 17 by means of peripherally distributed screws 10, indicated by a dot-dash line in the drawing. Such parts rigidly fixed to the casing are considered to belong to the latter in the appended claims. The rubber ring 6 forms an elastic intermediate member arranged between casing 1 7 and stuffing box member 2.

Rubber ring 6 tightly engages on the inner walls of the chamber ring 8, the periphery of the sleeve-like receiving member 22 and one side of the mounting flange 9, so that a reliable seal is ensured accompanied by radial mobility of the stuffing box member. Ring 6 can be tubular and be under the internal pressure of a gas or air, so that the pressure against the said walls is variable. Chamber ring 8 is sealed relative to the wall 17 by a disk-like gasket 18. The outward radial mobility of the stuffing box member 2 against the resilience of the ring 6 is ensured by a slip ring 1 6 via which the end of stuffing box member 2 adjacent the wall 17 is supported on the casing or chamber ring 8. Slip ring 1 6 can, for example, be made from polytetrafluoroethylene.

The mounting flange 9 and the flange member 21 of stuffing box member 2 are interconnected by bolts 11, of which a plurality are provided spaced in the peripheral direction of the flange.

The bolt ends extending through mounting flange 9 are pivotably secured thereto by means of heads 23. Nuts 1 5 screwed onto the other ends of bolts are each supported by means of a disk spring 1 3 and a part spherically surfaced washer 12 on flange member 21. The bores for the bolts 11 in mounting flange 9 and flange member 21 have larger diameters than the bolts so that on radial movement of stuffing box member 2 the bolts 11 can perform a pivoting movement, as indicated by dot-dash lines in the drawing. The possible movement of the shaft 1, together with the stuffing box member 2 and gland member 3 causing such pivoting movement of the bolts 11, is indicated by broken lines in the drawings.

Obviously, numerous variations of construction are possible. For example, the ring 6 can have an angular cross-section and can be expanded by the pressure of a fluid. However, it can also be solid or have a core of a foam material. In order to increase its resistance to chemical actions, the ring 6 can also be enveloped by covering 7, e.g. of polytetrafluoroethylene. In addition, numerous equivalent means are possible for the connection between the mounting flange 9 and the flange member 21, ensuring the support of stuffing box member 2 on flange 9 or on the casing while allowing limited mobility of member 2.

The elasticity of the ring 6, together with its sealing action, solves in a simple manner the problem indicated hereinbefore. Thus, the stuffing box can follow the shaft movements without there being increased wear on the packing material 5. The mobility of the stuffing box also makes it possible to use relatively hard packing material as is often necessary for sealing against relatively high pressures and with certain types of medium to be sealed. Obviously, numerous known embodiments of the stuffing box are possible, e.g. in accordance with French Patent 1,144,943 in which a space is provided between the inner wall of the sleeve-like receiving member of the stuffing box member 2 and packing material 5. This space is connected to a pressure source, so that the contact pressure of the packing material can be controlled by the pressure of a medium.

In one embodiment of the invention, a coolant can be passed continuously through the gap in around the ring 16 in order to prevent overheating of the ring and adjacent parts.

Claims

1. A stuffing box for sealing a shaft bushing in a casing by pressing a packing material against the shaft, the packing material being enclosed within a sleeve-like part of a stuffing box member surrounding the shaft and being axially compressed by a gland, wherein an elastic sealing member is located between the stuffing box member and the casing, which sealing member allows radial movement of the stuffing box member, and including generally axially extending connecting members for connecting the stuffing box member with the casing.

2. A stuffing box according to claim 1, including a bearing member via which the stuffing box member is axially engageable with the casing.

3. A stuffing box according to claim 2, wherein the bearing member has a disk-like slip ring engaging an end face of the sleeve-like part of the stuffing box member.

4. A stuffing box according to claim 1, 2 or 3, wherein the elastic sealing member is a rubber ring.

5. A stuffing box according to claim 4, wherein the ring has a hollow in which acts the pressure of a gaseous or liquid medium.

6. A stuffing box according to claim 5, wherein the ring is provided with connections for passing therethrough a cooling medium.

7. A stuffing box according to claim 4, 5 or 6, wherein the ring is enclosed in a ring chamber which is open towards the side of the sleeve-like part of the stuffing box member and on whose inner walls it elastically and sealingly engages.

8. A stuffing box according to any preceding claim, wherein the connecting members between the casing and the stuffing box member are bolts, pivotably securable at one end on the casing and whose other ends are pivotably connected to a flange of the stuffing box member.

9. A stuffing box according to claim 8, wherein the other ends of the bolts extend through the flange of the stuffing box member and are engaged /therewith via spheriially surfaced washers and elastic intermediate members.

10. A stuffing box substantially as hereinbefore described with reference to and as illuatrated in the accompanying drawing.