Coolant distribution and control system for metal rolling mills and the like
United States Patent Schaming Apr. 29, 1975 [54] COOLANT DISTRIBUTION AND CONTROL 3,613,418 10/197] Nara 72/8 SYSTEM FOR METAL ROLLING MILLS 3,77L730 11/1973 Nicolofl&#39; et ah... 239/550 1774,85] 1l/l973 Simmons 239/551 AND THE LIKE 3,845,635 12/1974 Perkins l r 1 1 v .1 239/550 Related U.S. Application Data Continuation-impart of Ser. No. 388.497. Aug. 15. 1973, abandoned.  
 Primary Examiner-Lloyd L. King Attorney, Agent, or FirmD. Paul Weaver {57] ABSTRACT To control the shape and uniformity of metal stock in a rolling mill, such stock is moved between liquid coolant distribution headers. Coolant discharge units are plugged into the opposing headers in a suitable 2% 26 1 4 3; array to produce a desired coolant spray pattern to i 72 8 13 control buckling or warping of the metal stock. A con- 1 0 care h trol fluid, such as air, is delivered to each coolant discharge unit to regulate internal valve means thereof so as to maintain locally the ideal coolant flow pattern. {56] References Cited The system embodies means to sense the condition of UNITED STATES PATENTS the moving metal stock and to convert sensed infor- 2,57l.583 /l95l Kolbach 7. 239/551 mation to an electrical signal which is fed to a control 3.3 8.52 10/1967 Lflckwmd 239/551 center, which monitors distribution of the control 3.4475155 6/1969 Cartwright... 239/551 fl id 3,533,261 1 1/1970 Hollander r 72/201 31504134 9/l97l Hinrichsen 72/13 21 Claims, 16 Drawing Figures l 22&#39; a 4/ 43 4, a 42 r 49 5? 54 4s 47 a- 1 s\\\ /62 C 69 48&#34; 55 2 M t Z L /73 mmicmz ssYs 3.880.888  
 SHEET 78F 8 COOLANT DISTRIBUTION AND CONTROL SYSTEM FOR METAL ROLLING MILLS AND THE LIKE This application is a continuation-in-part of prior copending application Ser. No. 388,497, filed Aug. 15, I973, for FLUID SUPPLY SYSTEM WITH UNI- FORM DISCHARGE CONTROL CARTRIDGE, now abandoned.  
  An increasing need exists in the metal rolling industry for more efficient, practical and economical systems to cool the rolls, metal plate and/or strip stock metal being produced in order to control the shape of the product within acceptable limits. Prior art cooling systems for this purpose are known, but generally speaking such systems have tended on the one hand to be ex cessively crude and therefore not fully capable of properly dealing with the problem, and on the other hand, some of the systems are extremely complex and costly, difficult to maintain, and impractical in view of the conditions of extreme rough handling which exist in many rolling mills.  
  An ideal cooling system for this particular purpose must possess the ability to deliver a liquid coolant onto the moving metal stock and/or rolls in a finely controlled manner so that localized areas of the stock exhibiting hot spots which cause warping and buckling can be cooled quickly by the delivery thereto of more coolant. Other areas of the metal stock may require a lesser degree of coolant at the same time or a different time during the processing of the material. Thus the cooling system must possess a considerable degree of flexibility and control to perform the required function adequately. At the same time, the system should be very rugged to withstand rough treatment which inevitably occurs around metal rolling operations and it should be constructed so that when damage occurs, important parts may be salvaged and reused in a repaired system. The construction of the system should be such that maintenance costs can be minimized even in a rough environment. It might be stated that an ideal system for this particular purpose would be one which is a compromise between the two extreme types of systems in the prior art which are either too crude to be fully effective or too complex and delicate to be practical and maintainable under working conditions.  
  It is therefore the principal object of the present invention to provide an improved cooling system to control the shape of rolled metal strip and plate stock in rolling mills. To achieve this objective, the invention utilizes liquid coolant distribution headers mounted on opposite sides of the moving metal stock, the headers receiving liquid coolant from a convenient remote source. Plugged into the opposing headers are individually removable and replaceable liquid coolant discharge units which form the heart of the invention in terms of its ability to deliver precisely regulated amounts of coolant to localized areas of the metal stock. The individual coolant discharge units according to the preferred form of the invention are mounted on the headers without critical sealing problems and in such a way that the units cannot accidentally separate from the header during usage but can be readily removed and salvaged intact should the header be crushed or damaged. In the preferred embodiment of the invention, ordinary commercially available pipe or tubing can be employed for the headers with an absolute minimum of machining required in the mounting of the coolant discharge units.  
  In addition to the above and a number of other improved mechanical features which will be fully developed in the application, the system embodies means for delivering a pressurized control fluid, such as air, to the individual liquid coolant discharge units on the headers without any comingling of the two fluids. Internal valve elements of the coolant discharge units are accurately individually regulated throughout the system in response to information transmitted by a sensor which may respond to temperature differences, speed changes or surface irregularities or other detectable variables in the metal stock. Different types of sensors may be utilized. Locally sensed information is transmitted to a converter unit which has the ability to convert the information to an electrical signal, which signal is fed to a suitable control center which may embody digital equipment or the like. The control center exerts the required control on the air distribution system which delivers controlling air or fluid to the individual liquid coolant discharge units so that these units at all times and under all conditions will deliver the proper volume and flow pattern of coolant to the metal stock in localized areas. The sensing, converting and control components may be conventional elements available on the open market and therefore these elements need not be dealt with in great detail in this application. However, they coact in the system with the unique headers and coolant discharge units in a very efficient and reliable manner which completely satisfies the particular need or application.  
  While the invention will be described in terms of a system for delivering a liquid coolant to metal stock in a rolling mill, it should be explained that the utility of the invention is broader than this and the invention could be employed to similarly control the delivery of coating materials, lubricants and the like onto moving webs.  
  Other features and advantages of the invention will become apparent during the course of the following detailed description.  
 In the accompanying drawings:  
  FIG. 1 is a diagrammatic view of a coolant distribution system embodying the invention;  
  FIG. 2 is an exploded perspective view of a coolant discharge unit or controller embodied in one form of the invention;  
  FIG. 3 is a central vertical longitudinal section through an assembled coolant discharge unit;  
  FIG. 4 is a fragmentary perspective view showing a discharge unit mounted on an associated header;  
  FIG. 5 is a fragmentary horizontal section through the header showing plural discharge units mounted thereon, on a reduced scale;  
  FIG. 6 is an exploded perspective view showing a modification of the discharge unit;  
  FIG. 7 is a similar view, partly in section, showing another modification of the discharge unit according to the initial embodiment of the invention;  
  FIG. 8 is an exploded perspective view of a coolant discharge unit and header according to a preferred embodiment of the invention;  
  FIG. 9 is a fragmentary perspective view of a discharge unit and header in assembled relationship;  
  FIG. is a fragmentary cross sectional view through the header shown in FIG. 9 and showing the mounting of plural coolant discharge units thereon;  
  FIG. 11 is a central vertical longitudinal section through a single coolant discharge unit according to the preferred embodiment;  
  FIG. 12 is an exploded perspective view of a single orifice spray head according to the preferred embodiment viewed from the rear side thereof;  
  FIG. 13 is an assembled perspective view of the same head;  
  FIG, 14 is an exploded perspective view of a dual orifice spray head constituting a modification of the preferred embodiment;  
 FIG. 15 is an assembled perspective view of the same;  
  FIG. 16 is a vertical cross sectional view on a reduced scale taken through the head in FIG. 15.  
  Referring to the drawings in detail wherein like numerals designate like parts, the numerals 20 and 21 designate a pair of opposed liquid distribution headers positioned on opposite sides of metal plate or strip stock 22 being fabricated in a metal rolling mill or the like. As will be fully described, the headers 20 and 21 carry a plurality of liquid coolant discharge units or controllers 23 which collectively deliver coolant in the required flow pattern to the opposite sides of the stock 22 to cool the same, thereby controlling the shape of the stock within required limits. The two headers 20 and 21 which supply liquid to all of the discharge units 23 mounted thereon receive their liquid supply from a remote conventional source 24 through a supply line 25 and branch lines 26 and 27 leading to the interiors of the two headers.  
  The liquid coolant output of the individual units 23 is accurately regulated in a manner to be fully described by a pressurized control fluid, such as air, which is delivered to the individual units 23 on the headers without comingling or mixing with the liquid coolant. By means of this separated control fluid, and associated controls, localized areas on one or both sides of the moving metal stock 22 can receive a greater or lesser amount of coolant to minimize warping or buckling as the need dictates. This is accom plished by causing one or more of the coolant discharge units 23 selectively to discharge a greater or lesser amount of coolant in a given region or regions of the metal stock.  
  In achieving this mode of operation, a sensing device 28, such as a heat sensor, surface irregularity sensor, or like means, delivers information indicative of the condition of the stock 22 to a converter unit 29, which receives this information and converts it into electrical signals which are then fed to a control center which may embody digital equipment or other known control means. In turn, the control center 30 exercises control over an air controller means, not shown, which regulates the supply of the pressurized control fluid to each of the coolant discharge units 23, in a manner to be de scribed. The system components 28, 29 and 30 and associated air controller means may be conventional ele ments known to the prior art and therefore need not be described in detail in this application. The primary subject matter of the invention in this application is embodied in the unique construction of the headers and the coolant discharge units 23 mounted thereon together with the means for delivering the two separated fluids to these units in such a way that the delivery of coolant to the metal stock may be finely regulated in the interest of controlling the shape of the metal stock.  
  With continued reference to the drawings, each header 20 or 21 embodies a channel member 31 defining a continuous interior header chamber 32 which receives liquid coolant through one or more of the delivery lines or pipes 27. The two headers may be of any required length depending upon the width of the stock 22 and the number of coolant discharge units 23 which they must carry in suitably spaced relationship to create the desired coolant flow or spray pattern. Each header further embodies on its forward side facing the stock 22 a relatively thick wall section 33 serving to close the open side channel member 31 and suitably secured thereto in a fluid-tight manner to form therewith a unitized structure. The opposite ends of each header are suitably plugged and are also fluid-tight.  
  At spaced intervals along each wall section 33, the same is bored at 34 from the exterior of the member and screw-threaded openings 35 of somewhat reduced diameters lead from the bores 34 into the chamber 32, as shown in FIG. 5. Each of these bored and screwthreaded openings receives one of the coolant discharge units 23 therein, as shown, and the particular number of openings and discharge units will be determined by the needs of a particular installation.  
  Each coolant discharge unit comprises a body portion 36 which is generally cylindrical and is provided throughout the major portion of its length with an interior bore 37. The interior end of the body portion 36 is closed by an end wall 38, and it is this end of the unit 23 defined by the wall 38 which projects into the header chamber 32 when the units 23 are assembled with the header, FIG. 5. When so assembled, external screw-threads 39 on the body portion 36 are engaged within the threaded openings 35 of the header, and enlarged concentric cylindrical lands 40 of each body portion 36 are received by the cylindrical bores 34. To assure an effective fluid seal between each unit 23 and the header 20 or 21 upon which it is mounted, each coolant discharge unit carries a pair of O-ring seals 41 held in annular grooves 42 formed in the land 40. These two spaced seals engage snugly within the bore 34 to tightly seal the same.  
  Between the two seals 41, FIG. 3, the land 40 has an annular groove 43 for the admission to the unit 23 of a control fluid, such as compressed air, from a convenient remote source. This air is delivered to each coolant discharge unit individually through a tube 44 leading to the header 20 or 21 from a pressurized source. Therefore, a number of the control fluid supply tubes 44, equal to the number of units 23, will lead to each header and will be suitably connected in sealed relation to an inlet port 45 provided on the wall 33 adjacent to each bore 34 and at right angles thereto. The air inlet ports 45 intersect and open into the bores 34 at the proper points to direct air into the annular channels or grooves 43 of the units 23 when the parts are assembled.  
  In each body portion 36, an internal longitudinal air passage 46 parallel to the bore 37 but separated there from leads from the bottom of the groove 43 to the interior end of the body portion where such end is plugged by a plug element 47. The passage 46 communicates with a radial cross passage 48 opening into the bore 37 close to the end wall 38. The outer end of the passage 48 is plugged by a small element 49 in the manufacturing of the body portion 36. The body portion also has one or more radial liquid coolant inlet ports 50 formed through its side wall somewhat outwardly of the end wall 38 and these ports admit liquid coolant into the chamber defined by the bore 37. In assembly. the ports 50 are disposed within the header chamber 32 centrally as shown in FIG. 5 to admit liquid coolant from the chamber 32 into the respective discharge units 23. While FIGv 3 shows the air passage 46 in the same plane as the ports 50 for ease of illustration, it should be understood that in actuality the passage 46 does not intersect one of the ports 50 but lies in a different plane therefrom somewhat further around the circumference of the body portion 36.  
  Mounted within the bore 37 for limited reciprocation is a control valve body 51 which controls the discharge of liquid coolant from the particular unit 23 in accordance with requirements as sensed by the device 28 and transmitted to the air controller, not shown, which in turn regulates the supply of controlling air to the particular tube 44 and port 45 leading to the groove 43 and air passages 46 and 48. At its inner end, the valve body 51 has a piston head 52 carrying an O-ring seal 53 or the like to separate the liquid receiving chamber 54 ahead of the piston head from the control fluid cham&#39; ber 55 behind the piston head. At its forward end, the body 51 has an enlarged valve head 56 carrying a packing or seal 57 adapted to engage a valve seat 58 of the body portion 36.  
  The valve body 51 is biased into a rearward or retracted position against control air pressure in the chamber 55 by a compression spring 59 contained within a frontal opening 60 in valve head 56. The forward end of this spring is engaged within a recess 61 of a skeleton or spider member 62, contained within an enlarged counter bore 63 in the forward end of body portion 36 and retained therein by a snap ring 64 as shown in FIG. 3. Immediately ahead of the cylindrical land 40, body portion 36 has a further enlarged flange 65, the rear face of which abuts the forward face of header wall 33 in assembly. A spray or discharge head 66 is attached fixedly to the forward face of flange 65 by pairs of oppositely facing screws 67 and 68. The head 66 has a recess 69 in its rear side leading to a reduced diameter bore 70 which opens through its forward end face. The recess and bore 69 and 70 receive an orifice member 71 having a reduced diameter tip 72 provided with a discharge opening 73 of a shape to provide the desired spray pattern for the unit 23 indicated at 74 in FIG. 1. The orifice member 71 is positioned in the recess 69 by a small locator pin 75 or key.  
  During the operation of the system, the condition of the metal strip or plate 22 is monitored by the device 28 and information as to hot spots, warpage or the like depending upon the type of sensor utilized, is fed to the converter 29 which feeds an electrical signal to the control center 30, which in turn regulates an air controller to supply each individual coolant discharge unit 23 through one of the tubes 44 and associated passages with the required control fluid (air) so as to open the valve head 56 relative to the seat 58 precisely the required amount to cause the particular unit 23 to discharge the amount of liquid coolant through the orifice member 71 and onto the element 22 in a localized region thereof to furnish the required cooling of that region. By this means, the metal strip or plate 22 will be cooled different degrees in different areas thereof to control its shape. This is done in the invention without any intermixing of the coolant and control fluids and through a very simple and direct-acting valve mechanism, as described. The pressurized control fluid in the chamber 55 behind the piston head 52 can always be regulated to drive the valve body 51 forwardly the required distance against the force of return spring 59 to achieve the necessary degree of discharge of coolant through the spray orifice. The control system, there fore, compensates automatically for inevitable fluctuations in the supply pressure of the liquid coolant from the source 24. That is to say, as the liquid pressure in the chamber 54 ahead of the piston 52 drops due to a fluctuation at the source and a given demand for coolant is sensed and dictated by the device 28, the responding control air entering the chamber 55 will advance the valve body 51 a greater distance in the body portion 36 to supply more coolant. The reverse will take place if the liquid pressure in the chamber 54 is excessive. In this case, the control air for a given demand situation will unseat valve head 56 to a lesser degree but because of greater liquid pressure, the demand for coolant will still be met accurately. In any case, the liquid coolant from header chamber 32 will flow directly through ports into chamber 54 of discharge units 23 and onto the work through orifice members 71, while the control fluid or air via the tubes 44, ports 45, grooves 43 and air passages 46 and 48 is being fed to chambers behind the pistons 52 of the discharge units. The system is reliable and efficient in operation, rugged in construction and relatively economical to construct and maintain. It has been found to satisfy all of the major requirements for a practical and economical cooling system for rolling mills as discussed previously in the specification.  
  FIGS. 6 and 7 show modifications of certain components of the discharge unit 23 to meet specified needs. More particularly, FIG. 6 illustrates a modified spray or discharge head 76 corresponding in the unit 23 to the described head 66 and being attached to the described flange by screws 77. Instead of the single orifice member 71 for the head 66, twin slant axis orifice members 78 and 79 are received in slant axis stepped openings 80 of the head 76 to produce a divergent axis twin spray pattern as indicated at 81 through the two spray discharge slots 82 of orifice members 78 and 79. As described for the orifice member 71, the members 78 and 79 are positioned in assembly by locator pins 83. Various other forms of multiple converging or diverging axis orifice members and spray heads may be employed on the units 23 to meet the coolant discharge needs of a given installation. In other respects, unit 23 remains unchanged in its construction and mode of operation.  
  Similarly, FIG. 7 shows a modification of the described one-piece valve body 51 in such cases as where a different control fluid to liquid coolant ratio is desirable and a larger control air piston head is needed. In this figure, the modified valve body is designated in its entirety by the numeral 84 and comprises a forward stem section 85 having a liquid discharge valve head 86 secured thereto at its forward end to serve the same purpose as the described valve head 56. On the rear end of the stem 85 is a piston head 87 of a first diameter which will be exposed in a chamber similar to the chamber 54 to liquid coolant pressure on its forward face tending to seat or close the valve head 86. The piston 87 and stem 85 have a central bore 88 for the guidance of a coaxial pin extension 89 on the forward end of a spacer enlargement 90 on a rear section 91 of the two part valve body 84. At the rear of spacer 90 is a second enlarged piston 92 which has its rear face exposed to the control fluid pressure when the front end of spacer 90 is abutting the smaller piston head 87 and the pin extension 89 is within the opening 88. When this dual piston arrangement is employed in the unit 23 in lieu of the described body 51, the area of the piston 92 exposed to control air pressure substantially exceeds the piston area exposed to coolant liquid pressure, namely, the area of the smaller piston 87. In all other respects, the construction and operation of the unit 23 remains unchanged.  
  FIGS. 8 through 16 of the drawings show a modified and preferred form of the invention which possesses the identical functional capabilities of the previous embodiment but has several distinct advantages thereover from a manufacturing standpoint and in terms of economy, ease of installation and maintenance. More par ticularly. the preferred embodiment eliminates costly machining and critical seals where the coolant dis charge units plug into the headers. This allows com mercial pipe or tubing to be used for making headers. When headers are crushed or damaged, they can be discarded without great loss and the plug-in discharge units are quickly disconnectable for salvage. A novel mechanical means for assembling the discharge units and connecting them to the headers in a secure manner whereby certain cap screws cannot back out is also embodied in the preferred form, along with a unique and accurate positioning means for the orifice assemblies on the discharge units without the need for separate lo cator pins or the like. Correct coolant spray patterns and spray angles are thus assured.  
  Referring now in detail to FIGS. 8 through 16, the preferred form of the invention employs coolant headers 93 in lieu of the previously-described headers and 21 in FIG. 1. Only one header 93 has been illus trated with associated components, but it should be fully understood that the system embodies a pair of headers and all associated components shown in FIG. 1, as previously described for the first embodiment. The header 93, as shown, may be formed from a section of commercial rectangular tubing of the necessary length and the liquid coolant may be supplied to the in terior chamber 94 of the header through one end thereof or through one or more lateral branch supply pipes 95 as suggested in FIG. 10. In any event, the chamber 94 of the header is closed and rendered liquid tight.  
  Instead of the bored openings 34 and threaded por tions 35 in the previous embodiment, one side wall portion of the header 93 is provided with the necessary number of openings 96 for the reception of the improved coolant discharge assemblies or units 97, to be described in full detail. The openings 96 need only be roughly to size without a close tolerance as the improved arrangement eliminates all critical sealing of the discharge units within the openings in which they are mounted.  
  Each discharge unit 97 comprises a body portion 98 which is cylindrical for placement in one of the open ings 96 with some clearance provided. The body portion 98 has a central bore 99 closed at its interior end by a wall 100. One or more radial coolant inlet ports 101 are formed through the side wall of body portion 98 at a location causing these ports to be centrally located in the header chamber 94, FIG. 10, when the parts are assembled. The body portion 98 is provided at its forward end with an enlarged head 102 which may be generaliy rectangular, as shown, or another convenient shape, if preferred. An enlarged bore por tion 103 in body portion 98 opens through the forward flat face 104 of head 102. This face 104 forms the bottom wall of a dovetail groove 105 provided at the forward side of head 102 adapted to interfit and interlock with a mating projection 106 on the rear of a separable orifice assembly mounting plate 107. While a dovetail connection has been illustrated, it should be understood that other forms of sliding interfitting or interlocking mechanical connections could be employed at this point.  
  The head 102 is secured firmly to the adjacent side wall of header 93 by a pair of cap screws 108 whose heads are received in countersunk recesses 109 in the head 102 and whose shanks are received in a pair of tapped openings 110 in the header 93. The plate 107, in turn, is attached to the head 102 by another pair of recessed cap screws 111 which are received by a pair of threaded openings 112 in the face 104 of head 102. By virtue of this mounting arrangement, after the parts are assembled, it is impossible for two screws 108 to become loosened or back out of the threaded openings 110, and therefore the mounting of the discharge units 97 on the headers is very secure.  
  In order to seal each unit 97 effectively, a single 0- ring seal 113 is utilized between the back face 114 of the head 102 and the adjacent outer face of the header 93. The body portion 98 has a longitudinal control fluid passage 115 corresponding to the passage 46, FIG. 3, formed in its side wall and intersecting near the rear of the bore 99 a radial passage 116 similar to the passage 48. The forward end of passage 115 communicates with a lateral passage 117 in the head 102, in turn connected with a short reverse longitudinal passage 118 which opens through the back face 114. This passage 118 receives control fluid (air) from a side port 119 in the wall of header 93 connected with a right angular opening or passage 120 also formed in the header wall for connection with individual control air supply tubes 12] corresponding to the tubes 44 of the prior embodiment. The back face 114 of head 102 is sealed to the header 93 around the air passages 118 and 119 by a small O ring seal 122. Neither of the passages 119 or 120 break into the chamber 94 of the liquid header, and as in the prior embodiment, there is no intermixing of the liquid coolant and the control air. Additionally, as shown, the matter of sealing the units 97 to the headers and sealing the control air interfaces is rendered much more simple and economical in the preferred embodiment as will be understood by anyone familiar with machining and manufacturing procedures.  
  Each coolant discharge unit 97 further comprises a discharge control valve body 123 substantially identical in formation and operation to the valve body 51 of the prior embodiment. This element includes a sealed piston head 124 in the bore 99 to separate the control air in a rear chamber 125 from the liquid coolant ahead of the piston head. It also includes a forward valve head 126 equipped with an O-ring seal 127 to engage the valve seat formed by shoulder 128. As in the prior embodiment, valve body 123 is biased rearwardly by a spring 129 retained by a spider member 130, in turn held in place by a snap ring 131. The mode of operation of the valve body 123 in the controlled dispensing of coolant from the unit 97 is exactly the same as described in the prior embodiment, and need not be repeated since the operation of the preferred embodiment is essentially unchanged.  
  The before-mentioned orifice mounting plate 107, FIG. 12, has a stepped opening formed therethrough including a larger diameter recess 132 in its rear face and a smaller diameter opening 133 leading from the recess 132 through the forward face of plate 107. The recess 132 and opening 133 are eccentrically formed to provide an important feature in the positioning of a stepped orifice body or head 134 whose two diameter portions 135 and 136 are likewise eccentrically formed to the same degree as the elements 132 and 133. Because of this, there is only one position in which the orifice body 134 may properly enter the opening means of the mounting plate 107 and when introduced or assembled in this position, FIG. 13, the discharge slot 137 of the orifice body will be properly aligned for the desired spray angle or spray pattern. The eccentricity of the elements 135 and 136 is graphically illustrated in FIG. 8 by center lines 138 and 139. This unique arrangement for positioning the orifice bodies 134 on the discharge units 97 eliminates the need for locator pins 75 or equivalent elements. The diameter portion 135 has a rear shoulder 140 for the mounting of another O-ring seal 141 which seals the orifice body to the mounting plate 107 when the parts are fully assembled. Immediately rearwardly of the orifice body 134 and seal 141 is a spacer ring 142, see FIG. 11, which maintains the orifice body 134 properly seated in the plate 107 and provides an important free flow zone or chamber 143 for the liquid coolant as it enters the orifice body 134 prior to discharging from the unit 97.  
  FIGS. 14 through 16 merely show modifications of the orifice mounting plate to accommodate dual orifice elements or bodies. It will be understood that these modified sub-assemblies are attachable to the same head 102 of body portion 98 without modification of that head or the associated attaching means. In FIGS. 14 through 16, an orifice mounting head 144 in lieu of the head 107 has an oblong cavity 145 in its rear face having a marginal recess 146 receiving a seal 147 which serves the same purpose in the assembly as the O-ring seal 14]. A rigid spacer element 148 is provided serving the same purpose as the spacer 142. A pair of slant axis orifice bodies 149 and 150 having eccentric diameter portions 151 and 152 are received within slant axis eccentrically stepped openings 153 of the mounting plate 144 to provide for the same accurate positioning of the spray discharge openings without the need for locator keys or pins. When the orifice elements are assembled as clearly shown in FIG. 15, this unit or subassembly attaches to the head 102 of body portion 98 in the identical manner above described and the spacer 148 maintains the orifice bodies 149 and 150 properly seated and establishes the mentioned liquid free flow zone 143 which is important to the most efficient oper&#39; ation of the discharge units 97.  
  Additionally, orifice heads or sub-assemblies of further modified form may be utilized in some cases including orifice mounting plates which are tapered or have a slightly different configuration from the plates I07 and 144. In all cases, the resulting sub-assemblies will be adapted for attachment to the head 102 without modification.  
  lt is to be understood that the forms of the invention herewith shown and described are to be taken as preferred examples of the same, and that various changes in the shape, size and arrangement of parts may be resorted to, without departing from the spirit of the invention or scope of the subjoined claims.  
  The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:  
  l. in a liquid coolant distribution system or the like, a coolant header having a chamber and having coolant intake means, plural spaced coolant discharge units plugged removably into the header along its length and each having a coolant discharge orifice means and a coolant inlet, said coolant inlet being disposed in the chamber of the header, pressure-responsive valve means in each coolant discharge unit to regulate the flow of coolant from each unit independently of other units on the header, and means to supply a pressurized control fluid to each discharge unit for activating said valve means of each unit in accordance with a demand for coolant from such unit.  
  2. The structure defined by claim 1, and an additional coolant header equipped with said plural discharge units mounted in opposed spaced relation to the firstnamed header with the discharge orifice means of the discharge units on the two headers in opposed relationship for applying coolant to opposite sides of an element arranged between the two headers.  
  3. The structure defined by claim I, wherein a wall of the header on which the coolant discharge units are disposed has plural openings into which the units extend removably, enlarged heads on the coolant discharge units exteriorly of the header and adapted to abut said wall of the header, threaded fastener means securing said heads fixedly to said header wall, and compressible fluid seals interposed between the opposing faces of the heads and said wall.  
  4. The structure defined by claim 3, and said means to supply a pressurized control fluid including passage means for the control fluid formed in each discharge unit and being entirely isolated from the coolant, each discharge unit having an internal chamber receiving the control fluid on one side of said pressure-responsive valve means.  
  5. The structure as defined by claim 1, wherein a wall of the header on which the coolant discharge units are mounted has plural openings formed therethrough including smooth bore portions and screw-threaded portions, each coolant discharge unit having a body portion to plug into one of said openings including a threaded part engaging within the screw-threaded portion and a cylindrical land to engage within said smooth bore portion, said land having an annular groove forming a part of said means to supply said control fluid, and a pair of ring seals on said land spaced on opposite sides of said groove and engageable sealingly in said smooth bore portion.  
  6. The structure defined by claim 3, wherein each enlarged head consists of a pair of slidably engaged interlocking parts, said threaded fastener means securing the interior one of said parts to said header wall, the ex terior part preventing said fastener means from backing out during usage of the system, and additional threaded fastener means securing the exterior part to said interior part.  
  7. The structure defined by claim 6, wherein said slidably engaged interlocking parts consist of a sliding dovetail connection.  
  8. The structure defined by claim 1, wherein each coolant discharge unit includes a plug body portion for entry into an opening in a wall of said header, said plug body portion having a bore and said pressure responsive valve means mounted for reciprocation in said bore, said valve means including a piston head on one end thereof and a valve head on its other end adapted for seating on a discharge mouth of said bore, said coolant inlet comprising at least one radial port formed through the side wall of said plug body portion on one side of said piston head and between the piston head and valve head, and said means to supply pressurized control fluid including a control fluid passage formed in the side wall of the plug body portion and opening into said bore on the other side of said piston head.  
  9. The structure defined by claim 8, and an enlarged head on one end of said plug body portion substantially abutting the exterior of said header wall, said bore of the plug body portion extending through said head, an orifice body mounting plate attached to the forward side of said head and having a cavity, and an orifice body including a coolant discharge aperture mounted within said cavity and held between said mounting plate and head.  
  10. The structure defined by claim 9, and a rigid locating element engaged with said orifice body and said mounting plate to accurately position said discharge aperture relative to said unit.  
  11. The structure defined by claim 9, wherein said cavity is a stepped cavity having a pair of eccentric bore portions, said orifice body being correspondingly stepped and having correspondingly eccentric diameter portions for entry into the eccentric bore portions to thereby accurately locate the orifice body and its discharge aperture circumferentially.  
  12. The structure defined by claim 11, and a spacer ring interposed between the orifice body and the front face of said head and maintaining the orifice body seated in said stepped cavity and establishing a free flow zone for liquid coolant in said discharge unit immediately rearwardly of said orifice body.  
  13. The structure defined by claim 12, and said orifice body mounting plate having an oblong recess in its rear face and having a pair of slant axis stepped cavities with eccentric bore portions formed in the bottom face of said oblong recess, a pair of orifice bodies having eccentric diameter portions insertable in said slant axis stepped cavities, an oblong spacer element insertable into the oblong cavity and engaging said orifice bodies and maintaining them seated in said stepped cavities, and an oblong seal mountable upon the rear of said orifice body mounting plate adjacent the mouth of said oblong recess.  
  14. A coolant distribution system for metal rolling mills or the like comprising a pair of spaced opposed coolant headers having coolant chambers and adapted to be mounted on opposite sides of rolled metal stock requiring cooling, plural coolant discharge units plugged into opposing sides of said headers in spaced relation to produce opposing coolant spray patterns, each discharge unit including a coolant discharge orifice, each discharge unit having a coolant chamber and coolant inlet port means leading into said chamber, said port means disposed in and directly communicating with a header chamber which is common to all discharge units mounted on such header, each discharge unit further having a control fluid inlet passage means isolated from said coolant chamber and said inlet port means and receiving a control fluid from a remote source, and a valve body mounted for movement in said discharge unit and including a piston head which separates said coolant chamber from said control fluid inlet passage means, said valve body further including a vaive head regulating the discharge of coolant from said chamber through said discharge orifice.  
  15. The structure defined by claim 14, and each header having spaced openings formed through a wall portion thereof, each opening receiving one of said coolant discharge units, each such discharge unit having an enlarged two part head arranged exteriorly of said wall portion and the interior part of said head opposing and abutting the exterior face of said wall por tion, said wall portion having screw-threaded openings beneath the interior part of said head, threaded fasteners extending through the interior part of said head and engaging within said screw-threaded openings, additional screw-threaded fasteners attaching the exterior part of said head to the interior part whereby the first named fasteners are effectively prevented from loosen ing, and ring seal means interposed between the abutting faces of said wall portion and interior part of said head, whereby sealing of said spaced openings is unnecessary to prevent leakage of coolant from said header around said discharge units.  
  16. The structure defined by claim 15, wherein said control fluid inlet passage means includes a control fluid inlet port in the interior part of said head opening through the face thereof abutting the header wall por tion, and another ring seal surrounding said inlet port and disposed between the abutting faces.  
  17. The structure defined by claim 16, and said control fluid inlet passage means further consisting of a control fluid passage formed in said discharge unit and leading to a chamber in the discharge unit on the side of said piston head remote from said coolant chamber, said inlet passage means additionally comprising a control fluid passage in said wall portion of said header for each coolant discharge unit, said last-named passage registering and communicating with said control fluid inlet port.  
  18. The structure defined by claim 14, and each discharge unit having a forward end head arranged exteriorly of one header wall and opposing such wall, a fluid seal interposed between said head and header wall, said head having a cavity, and a discharge orifice body mounted within said cavity, there being a free flow space for coolant in said head immediately rearwardly of said orifice body.  
  19. The structure defined by claim 18, and a spacer ring in said cavity interposed between the back of the orifice body and an opposing face of said unit, said spacer ring holding the orifice body seated and defining said free flow space.  
  20. The structure defined by claim 18, wherein said head embodies dual slant axis cavities for dual slant axis discharge orifice bodies.  
  21. The structure defined by claim 18, and said cavity being stepped and having eccentric bore portions, said orifice body having stepped eccentric diameter portions whereby the orifice body may be accurately positioned and locked within said cavity in a predetermined desirable use position.