This invention relates to a spray unit for supplying cooling and/or lubricating liquid to the rolls of a rolling mill or to the material being rolled therein.
In particular, the invention relates to a spray unit for a rolling mill, the unit being of the type comprising a spray bar which is adapted to be mounted adjacent the mill rolls and which has a manifold for continuously supplying liquid, a series of spray nozzles or sets of spray nozzles carried by, and spaced along, the spray bar and connected to a conduit; and, for each nozzle or sets of nozzles, a valve for controlling liquid flow from the manifold to the conduit, and fluid- operated controlling means for controlling the valve between an obturation position in which it prevents flow to the conduit and an open position in which liquid can pass to the conduit and thence to the spray nozzle or sets of nozzles.
A spray unit of that type has been described and illustrated in DE-A-2432012. As best shown in Figure 3, the spray unit of that patent specification employs a spool valve consisting of a valve body reciprocatably mounted in a bore which communicates with the manifold. At one end, the valve body carries a seal which can engage with a valve seat at an end of the bore. The valve body is. urged into the closed position by a helical spring and can be moved against the action of the spring into the open position by supplying compressed air supplied to a chamber formed between the other end of the bore and a piston carried by the valve body. When the valve is opened, coolant from the manifold can pass to the conduit connected to the spray nozzle or nozzles.
Particularly when the spray unit is to be controlled automatically for flatness control of the rolled product, each valve 'must have high reliability and must have a low response time. The large number of valves on a rolling mill and the frequency of operation of each necessitates high reliability over a relatively long period, if disruption of the mill operation is to be avoided. Equally, each valve must respond quickly to detection of non-flatness to minimise the production of non-flat product.
A valve of the type disclosed in DE-A-2432012 would not fulfil the above requirements. Detritus in the coolant would rapidly mar the contacting surfaces of the bore, the piston and the seal and cause breakdown of the valve in a relatively short time. Equally, the inertia of the valve body and the spring would ensure an unacceptably long response time.
In the spray unit of the present invention, the valve is a disc-like, peripherally-clamped, flexible diaphragm of substantially uniform thickness and section; such a diaphragm-type valve is already known per se from US-A-3863841. Further the valve is normally in the .open position, but is closed by flexure of the diaphragm into the obturating position, in which it closes an end portion of the conduit, solely by pressurable fluid of the controlling means acting directly on the diaphragm, the flexing of the diaphragm to the obturating position being in the direction of liquid flow from the manifold to the conduit.
In the invention, the only moving part of the valve is the diaphragm which has minimal inertia and which is little affected by the detritus in the liquid. The diaphragm is not engaged by any spring or the like, liable to cause wear of the diaphragm. Because the diaphragm flexes to the closed position of the valve in the direction of flow of the liquid, the pressure of the liquid assists in holding the valve closed, and, because the thickness and section of the diaphragm are substantially uniform, there is no discontinuity of strength across its area liable to cause breakdown.
The invention will be more readily understood by way of example from the following description of a rolling mill spray unit in accordance therewith, reference being made to the accompanying drawings, in which:
As seen in Figure 1 a rolling mill 2 has two roll assemblies, exemplified by work roll 4 and back-up roll 8, and work roll 6 and back-up roll 10. A workpiece W is shown as being rolled between the two assemblies. For the purpose of supplying rolling coolant/lubricant in the form of a fluid to the rolls and the workpiece, the mill is provided with spray bars 12, 14 arranged adjacent the mill and parallel to the roll axes. The spray bar 12 has spaced along its length sets of nozzles, each set comprising a jet nozzle 16 for directing fluid to the top back-up roll, a nozzle 18 for directing fluid to the top work roll and a nozzle 20 for directing fluid to the upper side of the workpiece.
Spray bar 14 is similar, having nozzles 22, 24 and 26 for directing fluid to the bottom back-up roll, the bottom work roll and the underside of the workpiece respectively.
Dealing now with details of each spray unit, reference is made to Figure 2 which shows a section through the spray bar 14, it being understood that the bar 12 is similar in most respects.
Thus, spray bar 14 is formed as a manifold 28 having a chamber 30 and an adaptor 32 is threaded into the manifold. A nozzle bar 34 attached to the manifold 28 has, for each set of nozzles, three passages 21, 23 and 25 which open to the exterior of the nozzle bar and which are threaded to receive the jet nozzles 22, 24 and 26. The passages 21, 23, 25 open to a normally plugged blind hole 36 within the nozzle bar 34, communicating with a tapped hole 42 aligned with an opening 40 through the adjacent wall of the manifold 28. A tubular member 38 passes through the hole 40 in the manifold and is threaded into tapped hole 42 there being one tubular member 38 in respect of each set of nozzles. As shown, member 38 extends across the chamber 30, i.e. transversely of the roll axes and partly into an opening in the opposite wall of the manifold 28.
Each set of jet nozzles 22, 24, 26 has its own control valve for controlling flow of lubricant from manifold chamber 30 to the nozzles. Each valve is similar and comprises an enclosure plate 44 secured to the exterior of manifold 28 by means of nuts 46 threaded on to studs 48, and defining compartment 50 aligned with the open end of tubular member 38. A pipe 52 is connected to a tube 54 which connects with the compartment 50 at 56. A diaphragm 58, conveniently made of a flexible polyurethane material, is securely clamped between the plate 44 and the manifold 28, so that it closes off compartment 50 and the opening in the adjacent wall of the manifold; the diaphragm is spaced slightly from the end of member 38, there being normally a gap. between the adjacent face 60 of the tubular member 38 and the face of the diaphragm.
A supply of compressed air is provided and this is fed as desired from each pipe 52 and tube 54 to the respective compartment 50 to deflect the diaphragm 58 into firm contact with the face 60 of the tubular member 38, thereby to close off the nozzle set and prevent the passage of lubricant from the manifold chamber 30 to the nozzles.
Coolant/lubricant fluid under pressure is supplied via the adapter 32 in the chamber 30 of the manifold 28. When the diaphragm 58 of any valve is not forced into obturating engagement with the tubular member 38, lubricant passes through the bore of that member into hole 36, and thence to the jet nozzles 22, 24, 26 to spray on to the rolls 6, 10 and the workpiece W.
When it is desired to cut off the supply of fluid from any particular nozzle set to the rolls and the workpiece compressed air is allowed to pass through the pipe 52 and the tube 54 into compartment 50 of the respective control valve. The polyurethane diaphragm is urged into engagement with the end face of the tubular member 38, thus preventing the fluid in the manifold 28 passing through the member 38 and hole 36 to the jet nozzles.
The valves constituted by the diaphragms 58 in Figure 2 may alternatively be operated under electrical control, by means of a solenoid for each valve and a control circuit for selectively energising the solenoids to bring the diaphragms 58 into obturating positions in relation to the ends of the member 38.
The electrical operation of the valves is illustrated in Figure 3 and 4, where the spray bar 14 is shown in outline, with the nozzles, represented by the uppermost 26, projecting therefrom. The enclosure 50 of each valve is dispensed with and plate 44 is replaced by a housing 70 containing the solenoid for the respective diaphragm 58.
In Figure 3, a separate line 72 for each valve leads from a control box 74 to the respective solenoid, which is also connected to a common return line 76. Selective energisation of lines 72 results in selected valve diaphragms 58 being brought to the closed positions.
Figure 4 shows a generally similar arrangement, but using encoded signals on a common control line 72. In this instance, the control box 74 incorporates an encoder which emits on line 72 a coded signal according to the particular valve that is required to be operated. Latched solenoids are employed and each has a decoder which decodes any signal designated for it and passes it to the solenoid to change over the condition of the latter. Control of individual valves may be effected manually or patterns of valves may be selected automatically under computer control.