GB2326214A - Valve maintenance in spray apparatus - Google Patents

Abstract

A valve has a body 2 having four inlets 3 for fluid to be controlled at one, planar end 4. Centrally of inlets 3 is a control fluid inlet 6. A shuttle chamber 8 extends away from the inlet 6, with drillings 9, extending from the inlets 3, arranged radially of the shuttle chamber. Shuttle chamber 8 has an opening 10 at an outlet end 11 of the body, where an outlet end plate 12 is bolted on, to which a spray nozzle 14 is fitted. End 41 of stem 31 of a shuttle 21 has a recess 42 for a closure elastomer block 43. This co-operates with end 44 of nozzle 14, to close the nozzle when control pressure is applied behind a piston 30 of the shuttle via inlet 6. Release of the control pressure allows the spring 37 to move the piston back, whereupon the pressure of the fluid being controlled acts on the block, adding to the spring force, and the valve snaps open. Plate 12 can be removed from the body to allow removal of the shuttle 21 for maintenance.

Description

SPRAY APPARATUS The present invention relates to spray apparatus typically for use in spraying rolls in a rolling mill, and in particular to a valve for use in such apparatus.

In a rolling mill, as rolling progresses, the rolls progressively heat up. This is a phenomenon not only of hot rolling, where the metal being rolled is at high temperature and can quickly heat the rolls, but also of cold rolling where the working of the metal heats it and the rolls. Where rolling is being carried out to close tolerances, as in production of strip, thin strip and foil, uneven heating of the rolls causes their diameter to change over their length. To alleviate this problem, it is known to spray the rolls with jets of cooling liquid. Depending on the type of mill and product rolled, different cooling liquids can be employed. These range from water, via water/oil emulsions, to oil and kerosene. The latter in particular is used for cold rolling of aluminium.

Conventionally, the cooling jets are supplied via valves, which can be individually controlled by air pressure, so that the camber of the rolls can be controlled by supplying more or less coolant to different zones of the rolls. The conventional pneumatically operated spray valves used, mounted on or in front of spray headers, are of the Normally Open (NO) type. They are controllably closable against the coolant pressure in the header with the application of compressed air, usually from a remotely installed, normally closed, directional control valve.

Conventional Normally Open valves have the disadvantage of not being readily able to be dismantled for replacement of their internal seals if necessary. This is in fact a serious shortcoming, since the valves are mounted in arrays of up-to four valves high and tens of valves wide. Further, each rolling station may have four such arrays. The implication is that whereas the individual valves may appear reliable; the overall spray apparatus has a much lower reliability.

The object of the present invention is to provide an improved valve, in.which the internal seals are readily replaceable.

According to the invention there is provided a normally open valve comprising: a body having an inlet adapted to be connected to a source of fluid to be controlled, an outlet end of the body and a shuttle chamber within the body, an outlet end plate connected to the outlet end of the body for closing a closure space within the shuttle chamber, a shuttle sealingly arranged in the chamber to open the valve unless control fluid is applied to the shuttle in the chamber for closing of the valve, the shuttle being removable from the body on removal of the outlet end plate.

Preferably the valve includes a guide in the chamber for the shuttle, the guide delimiting the closure space and the closure space being in communication with the inlet; and the shuttle comprises a piston slidable in the shuttle chamber and delimiting an actuating space within the chamber with a control fluid connection, a stem slidable in the guide and a closure member carried on the distal end of the stem within the closure space, the guide being removable for removal of the shuttle.

Conveniently the guide is sealed in the shuttle chamber and the stem is sealed to the guide, whereby the developed area over which the pressure of the fluid to be controlled acts is less than the developed area over which the control fluid acts. In other words, the cross-sectional area of the stem and the stem seal is less than that of the piston and its seal. The arrangement provides that the fluid to be controlled can be at a higher pressure than the control pressure, or where the pressure are similar that a strong actuating force can still be applied to the shuttle for rapid action of the valve.

In the preferred embodiment, the valve incorporates a spring acting between the piston and the guide for biasing the shuttle to its valve-open position.

Preferably a plurality of fluid passages connect the inlet or a plurality of inlets with the closure space. Conveniently the passages are arranged radially of the shuttle chamber. Provision of a plurality of passages reduces the pressure loss in the individual passages between the inlet(s) and the closure space. In turn this incrses the pressure drop across a nozzle, where such is provided on the outlet end plate, and improves the spray from the nozzle.

We have found that the valve of the invention is fast acting and enables control of flow through the valve by digital pulsing of the valve.

Accordingly, we provided a method of use of a valve of the invention equipped with a spray nozzle for spraying a determined flow rate of fluid (less than a maximum flow rate for the valve) by sequentially opening and closing the valve with an open/closed period ratio in accordance with the determined flow rate.

To help understanding of the invention, a specific embodiment thereof will now be described by way of example and with reference to the accompanying drawings, in which: Figure 1 is a front view of a valve of the invention; Figure 2 is a cross-sectional view on the line II-II in Figure 3; Figure 3 is a cross-sectional view on the line III-III in Figure 2; and Figure 4 is a diagrammatic view of the valve in use.

Referring first to Figures 1 to 3 of the drawings, the valve 1 there shown has an anodised aluminium body 2 having four inlets 3 for fluid to be controlled at one, planar end 4 of the body. Each inlet has a peripheral groove 5 for a sealing ring (not shown), whereby the body can be bolted to a manifold provided with corresponding outlets.

Centrally of the inlets 3 is a control fluid inlet 6 also with a peripheral sealing groove 7 for control fluid. Within the body, central of the inlets is a shuttle chamber 8 which extends away from the inlet end 4, with drillings 9, extending from the inlets 3, arranged radially of the shuttle chamber. The latter has an opening 10 at an outlet end 1 1 ofthe body. An outlet end plate 12 is bolted to the outlet end 11 ofthe body across its opening 10. The plate has an outlet throughbore 13 into which a spray nozzle 14 is fitted.

A shuttle 21 is arranged in the chamber 8 for control of fluid flow from the nozzle. Also an aluminium, shuttle guide 22 is provided in the chamber 8 at a step 23 between a slightly smaller diameter actuation portion 24 ofthe chamber and a slightly larger diameter, valve-closure portion 25 of the chamber. The guide is sealed to the chamber by a sealing ring 26 in a groove 27 and retained by a spring clip 28 in a groove 29 in the body. The shuttle 21, of nylon material, has a piston 30 and a stem 31. Each has a respective groove 32,33 for lip seals 34,35, the first seals the piston to the smaller diameter portion of the chamber and the second seals the stem in shuttle guide 22. To allow the piston to displace air between itself and the guide, a drilling 36 is provided in the side of the body. A spring 37 biases the shuttle towards the inlet end 4 of the body, minimising the actuation space 38 in absence of control pressure therein.

For flow of the fluid to be controlled from the drillings 9, into the closure portion ofthe shuttle chamber, scallop cut-outs 39 are made between the drillings and the chamber. It will be noted that the drillings can be of greater diameter than that of the nozzle, whereby because there are four drillings, there is negligible pressure loss in them compared with that across the nozzle. Even where the drillings are of similar cross-sectional area to that of the nozzle, the pressure loss across it is greater than across the drillings.

The distal end 41 of the shuttle stem 31 has a recess 42 for a closure member in the form of a synthetic elastomer block 43. This co-operates with the inner end 44 of the nozzle 14, so as to close the nozzle when control pressure is applied behind the piston via the control fluid inlet 6 into the actuation space 24 to move the piston forward and the block into abutment with the nozzle. Release of the control pressure allows the spring 37 to move the piston back, whereupon the pressure of the fluid being controlled acts on the block, adding to the spring force, and the valve snaps open. The cross-sectional area ofthe stem 31 and the stem seal 35 is less than that of the piston 30 and its seal 34, whereby if the actuation pressure is of the same order of pressure, say 4bar, as the pressure of the fluid to be controlled, the actuation force on the piston readily overcomes the spring pressure as well as the pressure on the block for rapid closure of the valve.

Whilst the valve has proved reliable in operation, the seals can wear and the structure of the valve lends itself to ready replacement of them. For this, the outlet plate 12 is unbolted, the spring clip 28 is removed and the guide 22 removed - with use of puller bolts (not shown) in threaded bores 45. The piston can then be withdrawn.

The worn seals can then be replaced and the valve quickly re-assembled, with minimum down-time. Alternatively, the entire valve assembly can be replaced with a spare one.

The original can then have its seals replaced.

Referring now to Figure 4, one of an array valves of the invention is there shown, in use in a rolling mill, connected to a coolant main or header 50, with the interposition of a manifold 51. The manifold has coolant drillings 52 aligned with the drillings 9 and a pressure airway 53 in register with the inlet 6. The nozzle 14 ofthe valve is arranged to direct a spray towards a roll 54. In use, when the roll is to be cooled to a specific temperature by spraying, the average flow rate from the nozzle is controlled by pulsing the valve open and closed by air pressure in the airway 53. This can be effected by conventional control means, including a solenoid valve 55 applying pressure air to a control line 57 to the valve or exhausting the actuation chamber ofthe valve to atmosphere via the outlet 58. The valve is under the control of a variable mar/space ration driver 59.

The invention is not intended to be restricted to the details of the above described embodiment. Modifications within the scope of the claims will be apparent to the man skilled in the art. For instance, different materials can be chosen for the different components ofthe valve, normally from anodised aluminium, stainless steel or high quality engineering plastics.

Claims (12)

CLAIMS:

1. A normally open valve comprises: a body having an inlet adapted to be connected to a source of fluid to be controlled, an outlet end of the body and a shuttle chamber within the body, an outlet end plate connected to the outlet end of the body for closing a closure space within the shuttle chamber, a shuttle sealingly arranged in the chamber to open the valve unless control fluid is applied to the shuttle in the chamber for closing of the valve, the shuttle being removable from the body on removal of the outlet end plate.

2. A normally open valve as claimed in claim 1, including a guide in the chamber for the shuttle, the guide delimiting the closure space and the closure space being in communication with the inlet; and the shuttle comprises a piston slidable in the shuttle chamber and delimiting an actuating space within the chamber with a control fluid connection, a stem slidable in the guide.

3. A normally open valve as claimed in claim 2, including a closure member carried on the distal end of the stem within the closure space, the guide being removable for removal of the shuttle.

4. A normally open valve as claimed in claim 2 or claim 3, including a seal for sealing the guide in the shuttle chamber.

5. A normally open valve as claimed in claim 4, including wherein the stem is sealed to the guide, whereby the developed area over which the pressure of the fluid to be controlled acts is less than the developed area over which the control fluid acts.

6. A normally open valve as claimed in any one of claims 2 to 5, including a spring acting between the piston and the guide for biasing the shuttle to its valve-open position.

7. A normally open valve as claimed in any preceding claim, including a plurality of fluid passages connecting the inlet or a plurality of inlets with the closure space.

8. A normally open valve as claimed in claim 7, wherein the passages are arranged radially of the shuttle chamber.

9. A normally open valve as claimed in any preceding claim, including a spray carried by the outlet end plate.

10. A normally open valve as claimed in claim 9, in combination with means for pulsing the valve open and closed.

11. A method of use of a valve as claimed in claim 10, the method consisting in spraying a determined flow rate of fluid (less than a maximum flow rate for the valve) by sequentially opening and closing the valve with an open/closed period ratio in accordance with the determined flow rate.

12. A normally open valve substantially as hereinbefore described with reference to Figures 1 to 3 of the accompanying drawings.