AU634091B2

AU634091B2 - Valve seat grinding machine

Info

Publication number: AU634091B2
Application number: AU85596/91A
Authority: AU
Inventors: George Terence Fletcher
Original assignee: RICO Pty Ltd
Current assignee: RICO Pty Ltd
Priority date: 1990-10-10
Filing date: 1991-10-04
Publication date: 1993-02-11
Anticipated expiration: 2011-10-04
Also published as: GB2264075B; AU8559691A; GB9202911D0; GB2264075A

Description

634091

AUSTRALIA

Patents Act 1990 Name of Applicant RICO PTY LTD Actual Inventor GEORGE TERENCE FLETCHER Address for Service GRANT ADAMS COMPANY Patent Trade Mark Attorneys Level 9 National Mutual Centre 144 Edward Street BRISBANE QLD 4000 f AUSTRALIA.

SInvention Title "VALVE SEAT GRINDING MACHINE" Details of Associated Provisional Applications S£ Numbers PK2726 The following statement is a full description of the invention including the best method of performing it known to me.

u- l 1 THIS INVENTION relates to a valve seat grinding machine.

The invention is particular suitable for, but not limited to, re-grinding of valve seats in parallel, slide or gate valves or the inclined seats in non-return valves.

The valve seats in valves (eg. for steam lines) are subject to wear with use an the scratches or other wear on the seats can allow leakage of steam or fluids at high pressure and/or temperatures. This, of course, is highly undesirable, and so regular resurfacing of the valve seats is required to ensure proper sealing of the valves.

The maintenance of the valves can often be made more difficult in that many valves are welded into the steam or fluid lines and so maintenance must be carried out in-situ.

Methods of, and apparatus for, the re-lapping of valve seats have been developed to enable in-situ lapping of the valve seats and one example is disclosed in AU-B-14442/83 (559693) (Hunter Valley Construction Pty Ltd). In some valves, scratches, pits or other wear on the seats can be so deep that to remove them with a lapping machine, which is primarily designed to polish the seats, can be a very slow process.

It is an object of the present invention to provide a simple, yet efficient device of the in-situ grinding of valve seats in large valves.

'°It is a preferred object to provide a device 30 which can grind both vertical and inclined seats in valves.

It is a further preferred object to provide a device where the pressure applied on the seats by the grinding disc is readily adjustable.

Other preferred objects of the present r*mrrprmrc~ invention will become apparent from the following description.

In one aspect, the present invention resides in a valve seat grinding device including: a frame; means for mounting the frame on a valve once a valve closure means has been removed; a first shaft mounted on the frame; a rotating carrier on the first shaft; a grinding disc mounted on a second shaft rotatably mounted on the rotating carrier, the second shaft being parallel to, but spaced from, the first shaft; first drive means to rotate the rotating carrier; second drive means to rotate the grinding disc; the grinding disc carrying an abrasive medium on its surface at least in the area coincident with the valve seat as the grinding disc moves in an orbital path about the axis of the first shaft.

.°.Preferably, the frame includes a vertical leg depending from a head. Preferably, the head is bolted to the valve body when a valve bonnet, spindle and valve 00 0 25 member have been removNT ',Jm the valve.

as l Preferably, the head is mounted on a slide o assembly for movement parallel to the axis on the valve.

Preferably, the rotating carrier is journalled 0: on the first shaft by suitable bearings. Alternatively, 30 the rotating carrier may be fixed to the first shaft and the latter may be journalled in bearings on the leg.

0 Preferably, the second shaft is journalled in bearings adjacent the periphery of the rotating carrier, and the grinding disc has an outwardly directed grinding face.

4 Preferably, the first driving means for the rotating carrier includes a belt and pulley drive, or a chain and sprocket drive, driven by an air motor, an electric motor or a hydraulic motor on the head.

Preferably, the second drive means includes a driving pulley or sprocket on the motor which drives a double pulley or sprocket rotatably journalled on the first shaft, which in turn, drives a driven pulley or sprocket on the second shaft.

The drive means are preferably arranged so that the rotating carrier has a low rotational speed but that the grinding disc has a high rotational speed.

In a second aspect, the present invention resides in a method for grinding a valve seat of a valve including the steps of: mounting a frame on the valve once a valve closure means of the valve has been removed; rotatably driving a rotating carrier on a first shaft, on the frame, coaxial with the valve seat; and rotatably driving a grinding disc mounted on a second shaft rotatably mounted on the rotating carrier, the second shaft being parallel to, but spaced from, the first shaft, the grinding disc carrying an abrasive medium on its surface at least in the area coincident with the valve seat as ,the grinding disc moves in an orbital path about the axis of the first shaft.

To enable the invention to be fully understood, a preferred embodiment will now be described with reference to the accompanying drawings in which: FIG 1 is an elevational view of the device in a valve; FIG 2 is a part-sectional view of the device; and.

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4.m i i V+l 4 44 4 4,14 4a FIG 3 is an end elevational view of the drives for the rotating carrier and the grinding disc.

Referring to FIG 1, the valve seat grinding device 10 is fitted to the valve body 11 when the valve bonnet and its associated hardware have been removed to enable access to the valve seats 12, 13, the valve body being left in-situ in the steam pipe line (not shown).

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The device 10 has a head 15 which is mounted on a slide assembly 16, bolted to the peripheral flange 17 of the valve body, to enable the device to be moved in the direction of the arrow A parallel to the axis of the valve.

A leg 18 depends from the frame 15 and has a shaft 19 welded at its lower end to be co-axial with the bore of the valve 11.

'A rotating carrier 20 is rotatably journalled on a bearing 21 on the shaft 19 and a grinding disc 22 has its shaft 28 rotatably journalled in a bearing 24 adjacent the periphery of the rotating carrier A small driving pulley 25 is mounted on the output shaft 26 of an air motor 27 mounted on the head 15 and it drives a V-belt 28 which passes around the larger diameter rotating carrier 20 so that the rotating carrier is underdriven relative to the air motor 27.

A large driving pulley 29 on the shaft 26 of the air rnrtor 27 drives one side of a double pulley rotatably journalled on bearings 31 on the shaft 19, via a V-belt 32. The other side of the double pulley is connected to a small driven pulley 33, on the shaft 23 of the grinding disc 22 via a V-belt 34. By this arrangement, the grinding disc is considerably overdriven relative to the rotational speed of the shaft 26 of the air motor 27. Abrasive paste (not shown) is applied to the grinding surface 35 to grind the adjacent •r valve seat face 12.

30 In use, the device 10 is fitted to the valve 11 and the air motor is started. The rotation of the rotating carrier will move the grinding disc 22 in an orbital path as the grinding disc rotates at high speed about the axis of its shaft 23. By adjustment of the slide assembly 16 (eg. by a screw-feed, not shown), the grinding face 35 of the grinding disc is brought into contact with the valve seat 12 and the seat is progressively ground to remove any scratches, pits or the like. The necessary contact pressure of the grinding face 35 on the valve seat 12 is effected by adjustment of the sliue assembly 16.

When the valve seat 12 has been ground suitable for lapping, the device may be arranged to grind the valve seat 13.

While the rotating carrier 20 has been shown as journalled on thL shaft 19, the rotating carrier may be keyed to the siaft 19 which in turn, may be journalled in bearings at the lower end of the leg 18.

Various changes and modifications may be made to the embodiment described and illustrated without departing from the scope of the present invention defined in the appended claims.

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Claims

1. A valve seat grinding device including: a frame; means for mounting the frame on a valve once a valve closure means has been removed; a first shaft mounted on the frame; a rotating carrier on the first shaft; a grinding disc mounted on a second shaft rotatably mounted on the rotating carrier, the second shaft being parallel to, but spaced from, the first shaft; first drive means to rotate the rotating carrier; second drive means to rotate the grinding disc; the grinding disc carrying an abrasive medium on its surface at least in the area coincident with the valve seat as the grinding disc moves in an orbital path about the axis of the first shaft.

2. A valve seat grinding device according to Claim 1 wherein: the frame includes a vertical leg depending from a head, the head being bolted to the valve body when a valve bonnet, spindle and valve member have been 25 removed from the valve.

3. A valve seat grinding device according to Claim 2 wherein: the head is mounted on a slide assembly for movement parallel to the axis of the valve.

4. A valve seat grinding device according to Claim 2 wherein: the rotating carrier is journalled in bearings on the first shaft, or the rotating carrier is fixed on the first shaft and the first shaft is journalled in bearings on the leg; Ir i Io K' I, id ,q j 0* I 0~ IC 144440 8 the second shaft is journalled in bearings adjacent the periphery of the rotating carrier; and the grinding disc has an outwardly-directed grinding face.

A valve seat grinding device according to Claim 2 wherein: the first driving means for the rotating carrier incll.des a belt and pulley drive, or a chain and sprocket drive, driven by an air motor, an electric motor, or a hydraulic motor on the head; and the second drive means includes a driving pulley or sprocket on the motor which drives a double pulley or sprocket t;otatably journalled on the first shaft, which in turn, drives a driven pulley or sprocket on the second shaft of the grinding disc.

6. A valve seat grinding device according to Claim 5 wherein: the first and second drive means are arranged so that the rotating carrier has a low rotational speed, but the grinding disc has a high rotational speed.

7. A valve seat grinding device according to any one of Claims 1 to 6 wherein: the first shaft mounted on the frame is coaxial with the valve seat and the bore of the valve.

8. A method for grinding a valve seat of a valve including the steps o:: mounting a frame on the valve once a valve closure means of the valve has been removed; rotatably driving a rotating carrier on a 30 first shaft, on the frame, coaxial with the valve seat; and rotatably driving a grinding disc mounted on a second shaft rotatably mounted on the rotating carrier, the second shaft being parallel to, but spaced from, the first shaft, the grinding disc carrying an abrasive medium on its surface at least in the area It I i:: I ST I I II I J_ I~ I r i, coincident with the valve seat as the grinding disc moves in an orbital path about the axis of the first shaft.

9. A valve seat grinding device substantially as hereinbefore described with reference to the accompanying drawings. A method for grinding a valve seat of a valve substantially as hereinbefore described with reference to the accompanying drawings. DATED this nineteenth day of November 1992. RICO PTY LTD, By their Patent Attorneys GRANT ADAMS COMPANY. t 4 a AC C i