PLUGS FOR RADIATORS

Abstract: A plug for a radiator, which is a pressing of sheet metal, and which comprises an externally threaded tubular body (15) portion for engagement with a complementary screw thread in an aperture in a radiator, and a head portion (39) adapted to be engaged by a driving tool for screwing the body portion into the aperture in the radiator. The plug has a formation for receiving a seal element for providing a fluid type seal between the plug and radiator, for example a radially outwardly extending annular flange (40) which enables an O-ring to be compressed between the flange (40) and the surface of the radiator in contact therewith. The plug may also comprise a tubular portion (36) for receiving a bleed valve member. The invention also relates to a method of making a plug as above described comprising performing a number of pressing operations on a sheet metal blank.

Description: Title: PLUGS FOR RADIATORS This invention relates to plugs intended primarily, and herein described with reference to their use, for heating radiators (although it will be appreciated that plugs according to the invention will be usable for other purposes). A plug according to the invention is usable to blank off an aperture in a radiator, which aperture is not required for flow of water to or from the radiator. Such a plug may incorporate a bleed valve. Hitherto plugs for radiators, whether or not they incorporate bleed valves, have been made by machining from solid material. Such manufacture is expensive both in the manufacturing operations required and in the use of material. According to one aspect of the present invention, we provide a plug for a radiator, which is a pressing of sheet metal. The plug preferably comprises a body portion of tubular configuration, provided on its external surface with a screw thread for engagement with a complementary screw thread provided in an aperture in a radiator, and a head portion adapted to be engaged by a driving tool for screwing the body portion of the plug into the aperture in the radiator. Preferably the head portion of the plug has an external surface including opposed flat portions for torque-transmitting engagement by a spanner, for screwing the body portion of the plug into the aperture in the radiator. Conveniently the head portion is of square or hexagonal configuration to afford a number of such pairs of flat surface portions. The plug may be provided with a formation for receiving a sealing element, to provide a fluid-tight seal between the plug and radiator. Such formation preferably comprises a radially outwardly extending annular flange, between the body and head portions of the plug. Such a flange affords an abutment surface which enables a sealing element such as an O-ring to be compressed between the flange and the surface of the radiator surrounding the aperture therein, to provide a seal. Alternatively or in addition, an annular groove may be provided between the body and head portions of the plug for receiving a sealing element such as an O-ring. The flange may include an inclined rim which provides a constraint against radial extrusion of an O-ring compressed by the flange. If the plug is simply a closure plug, the head portion of the plug may be closed. If, on the other hand, it is a plug having a bleed valve, it may include a tubular portion extending lengthwise of the plug through at least part of the body portion and/or the head portion thereof, for receiving a bleed valve member. Such tubular portion may include an end portion having an aperture arranged to be closed by the tip of the bleed valve member. A conventional bleed valve member is an externally threaded component with a conical tip and a head enabling the bleed valve member to be turned by a key; the tubular portion of the plug will then be provided with an internal screw-thread for engagement by the bleed valve member. Preferably said tubular portion of the plug for receiving the bleed valve member is inset lengthwise of the plug from the free end of the head portion of the plug, so that the head of a bleed valve does not protrude beyond the end of the plug. According to another aspect of the invention, we provide a method of making a plug for a radiator, comprising performing a number of pressing operations on a sheet metal blank. Preferably the blank is a circular blank, and the method includes a pressing operation or operations to form the blank into a generally cup-shaped component having a peripheral wall and an end wall. A further pressing operation or operations may then form the end wall and an adjacent part of the peripheral wall to a head portion of the plug, whilst a part of the peripheral wall remote from the end wall is formed to a body portion of the plug. Preferably the method comprises forming the head portion of the plug to a configuration cooperable with a driving tool, for example including opposed flat external surface portions for engagement by a spanner or the like, for screwing the body portion of the plug into an aperture in the radiator. The head portion may be formed to a square or hexagonal configuration to afford such flat surface portions. Preferably the method further comprises forming a radially outwardly extending annular flange between the body and head portions of the plug, and may further comprise providing an inclined rim on the flange. If the plug is to receive a bleed valve, the method may further comprise the step of forming a tubular portion extending lengthwise of the plug through at least part of the head portion and/or body portion thereof, to receive the bleed valve. Preferably said tubular portion is formed from an end wall portion of the head portion of the plug. These and other features of the invention will now be described by way of example with reference to the accompanying drawings, of which:- Figure 1 shows successive stages in manufacture of a first embodiment of plug according to the invention; Figure 2 shows successive stages in manufacture of a second embodiment of plug according to the invention. Referring firstly to Figure la . of the drawings, this shows a circular blank 10 of sheet metal which is the starting point for manufacture of a plug according to the invention. The first operation carried out on the blank is a pressing or drawing operation, to produce a cup-shaped component with a cylindrical peripheral wall 11 and a flat end wall 12, as shown in Figure lb. The next operation to be carried out on this component is a further pressing or drawing operation, to produce the component shown in Figure lc_ wherein the end wall 12 has been formed into what is to be the head portion 13 of the plug, with an hexagonal, square or other appropriate external shape for engagement with a driving tool such as a spanner. The component of Figure lc. is then subjected to a further pressing operation to produce the component shown in Figure Id. which has a radially outwardly extending annular flange 14, constituted by a double thickness of the sheet metal, between the head portion 13 and a body portion 15 which is tubular and whose diameter is reduced compared with the previous diameter of the tubular wall 11. A further pressing operation carried out on the component of Figure Id . produces the component shown in Figure le. in which the flange 14 has an inclined rim 16. A final pressing operation shapes the component thus formed to the configuration shown in Figure If. The body portion 15 is radially expanded in a region 15a . remote from the flange 14 so that an annular groove 17 is defined adjacent the flange. The expanded portion 15a . of the body portion of the plug is provided with an external screw-thread, e.g. by a subsequent thread rolling process, to enable it to be screwed into an aperture having a complementary internal thread in a radiator. The annular groove 17 provides for reception of a sealing element such as an O-ring, which is compressed by the flange 14 against the surface of the radiator surrounding the aperture therein to provide a sealing action. Inclined rim 16 on flange 14 protects the O-ring and prevents radial extrusion thereof as it is compressed. Referring now to Figure 2 of the drawings, this shows successive steps in the manufacture of a plug according to the invention which is adapted to receive a bleed valve. Figure 2a . shows a circular blank 30 of sheet metal which in a first pressing operation is formed into the cup-shaped component shown in Figure 2b which has a cylindrical wall 31 and a closed end wall 32. A further pressing operation deepens the cup-shaped component and reduces its diameter, to a configuration shown in Figure 2c. The next pressing operation is to provide the closed end 32 of the cup- shaped component with an inwardly extending, itself cup-shaped, recess 33 with a tubular lateral wall 34 and end wall 35, as shown in Figure 2d, A further operation on this component provides it with the configuration shown in Figure 2e, wherein part of the wall 34 is elongated and reduced in diameter as shown at 36, whilst a remaining part of the wall 35 is formed into a reentrant configuration as indicated at 37 and pierced to provide it with a small diameter aperture 38. The internal diameter of the wall portion 36 is suitable for tapping to form it with an internal screw-thread to be engaged by a bleed valve screw member whose tip is able to close the aperture 38. The component shown in Figure 2e_ is now subjected to a further pressing operation which provides the component shown in Figure 2f. The wall 32 surrounding the recess 33 is displaced to provide a head portion 39 of square or hexagonal peripheral configuration. Further pressing operations are then carried out analogous to the pressing operations above described with reference to Figures ld_ to If. Firstly a radially extending annular flange 40 is provided adjacent the head portion 39, as shown in Figure 2g The flange 40 is provided with an inclined rim 41, as shown in Figure 2h_. A body portion of the plug is then provided with an expanded wall portion 42 which is subsequently provided with a screw-thread, and which defines an annular recess 43 between it and the flange 40. A thread is then tapped in the wall portion 36 for the bleed valve member and a thread is then provided, for example, by a thread cutting or rolling operation on the wall portion 42. The invention thus provides a plug for a radiator, which may be one receiving a bleed valve, which is made by pressing operations on sheet metal and thus is more economical than manufacture of such plugs by machining from a solid as has been known hitherto. The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims: CLAIMS: 1. A plug for a radiator, which is a pressing of sheet metal. 2. A plug according to claim 1 comprising a body portion of tubular configuration, provided on its external surface with a screw thread for engagement with a complementary screw thread provided in an aperture in a radiator, and a head portion adapted to be engaged by a driving tool for screwing the body portion of the plug into the aperture in the radiator. 3. A plug according to claim 2 wherein the head portion of the plug has an external surface including opposed flat portions for torque transmitting engagement by a spanner, for screwing the body portion of the plug into the aperture in the radiator. 4. A plug according to claim 3 wherein the head portion is of square or hexagonal configuration to afford a number of such pairs of flat surface portions. 5. A plug according to any one of the preceding claims which is provided with a formation for receiving a sealing element, to provide a fluid tight seal between the plug and radiator. 6. A plug according to claim 5 wherein the formation comprises a radially outwardly extending annular flange, between the body and head portions of the plug. 7. A plug according to any one of claims 2 to 5 wherein an annular groove is provided between the body and head portions of the plug for receiving a sealing element. 8. A plug according to claim 6 wherein the flange includes an inclined rim which provides a constraint against radial extrusion of a sealing element compressed by the flange. 9. A plug according to any one of claims 2 to 8 wherein the head portion of the plug is closed. 10. A plug according to any one of claims 2 to 8 wherein the head portion of the plug includes a tubular portion extending lengthwise of the plug through at least part of the body portion and/or the head portion thereof, for receiving a bleed valve member. 11. A plug according to claim 10 wherein the tubular portion includes an end portion having an aperture arranged to be closed by the tip of the bleed valve member. 12. A plug according to claim 10 or claim 11 wherein the bleed valve member is an externally threaded component with a conical tip and a head enabling the bleed valve member to be turned by a key, and wherein the tubular portion of the plug is provided with an internal screw thread for engagement by the bleed valve member. 13. A plug according to any one of claims 10 to 12 wherein the tubular portion of the plug for receiving the bleed valve member is inset lengthwise of the plug from the free end of the head portion of the plug, so that the head of a bleed valve does not protrude beyond the end of the plug. 14. A method of making a plug for a radiator, comprising performing a plurality of pressing operations on a sheet metal blank. 15. A method according to claim 14 wherein the blank is a circular blank, and wherein the method includes a pressing operation or operations to form the blank into a generally cup-shaped component having a peripheral wall and an end wall. 16. A method according to claim 15 wherein a further pressing operation or operations then form the end wall and an adjacent part of the peripheral wall to a head portion of the plug, whilst a part of the peripheral wall remote from the end wall is formed to a body portion of the plug. 17. A method according to claim 16 comprising forming the head portion of the plug to a configuration cooperable with a driving tool. 18. A method according to Claim 17 wherein the configuration includes opposed flat external surface portions for engagement by a spanner or the like, for screwing the body portion of the plug into an aperture in the radiator. 19. A method according to claim 18 wherein the head portion is formed to a square or hexagonal configuration to afford such flat surface portions. 20. A method according to any one of claims 16 to 19 further comprising forming a radially outwardly extending annular flange between the body and head portions of the plug. 21. A method according to claim 20 further comprising providing an inclined rim on the flange. 22. A method according to any one of claims 14 to 21 wherein the plug is to receive a bleed valve. 23. A method according to claim 22 wherein the method further comprises the step of forming a tubular portion extending lengthwise of the plug through at least part of the head portion and/or body portion thereof, to receive the bleed valve. 24. A method according to claim 23 wherein the tubular portion is formed from an end wall portion of the head portion of the plug. 25. A plug for a radiator substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings. 26. A method of making a plug for a radiator substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings. 27. Any novel feature of novel combination of features disclosed herein or in the accompanying drawings.

Applicants: MARTIN & FIELD LTD, MARTIN & FIELD LIMITED
Application year: 1995
Main classification: F24H9
IPC codes: B21D53, F24D19, F24H9, F28F9