Abstract:
A gland plate includes a rigid, disk-shaped element that includes at least one radially extending wall having a thickness of from about 0.1 to 4 mm.

Description:
RELATED APPLICATIONS 
   The present application is a 35 U.S.C. 371 national phase application of PCT International Application No. PCT/GB2003/002688, having an international filing date of Jun. 23, 2003, and claiming priority to Great Britain Patent Application No. 0214636.3, filed Jun. 22, 2002, the disclosures of which are incorporated herein by reference in their entireties. The above PCT International Application was published in the English language and has International Publication No. WO 2004/001258 A1. 
   FIELD OF THE INVENTION 
   This invention relates to gland plates and particularly, but not exclusively, to gland plates which are fitted to or form part of mechanical seals which are used in connection with rotating devices or equipment in many different types of industries. 
   BACKGROUND OF THE INVENTION 
   A mechanical seal comprises a “floating” component which is mounted to be axially movable around the rotary shaft of, for example, a pump, and a “static” component which is axially fixed, typically being secured to a housing. The floating component has a flat annular end face, i.e. its seal face, directed towards a complementary seal face of the static component. The floating component is urged towards the static component to close the seal faces together to form a sliding face seal, usually by means of one or more spring members. In use, one of the floating and static components rotates; this component is therefore referred to as the rotary component. The other of the floating and static components does not rotate and is referred to as the stationary component. 
   Those seals whose floating component is rotary are described as rotary seals. If the floating component is stationary, the seal is referred to as a stationary seal. 
   If the sliding seal between the rotary and stationary components are assembled and pre-set prior to despatch from the mechanical seal manufacturing premises, the industry terminology for this is “cartridge seal”. If the rotary and stationary components are despatched individually (unassembled) from the mechanical seal manufacturing premises, the industry terminology for this is “component seal”. 
   Mechanical seals are used in all types of industries to seal a variety of different process media and operating conditions. The general industry term which defines the area adjacent to the process media is “inboard”. The industry term which defines the area adjacent to the atmospheric side is “outboard”. 
   With the exception of the mechanical seal faces, the most costly item of a cartridge mechanical seal is the gland plate. The raw material for a gland plate is typically either cast metal or a solid metal bar. Alternative materials such as plastic are also occasionally used. Subsequent machining operations on the gland plate raw material are required in order to accurately fit the mating components. 
   For most types of mechanical seals, typically, one seal gland is employed for each size of seal in both single and double seal formats. With over 30 standard seal sizes, in any given product range and at least two gland formats, a company&#39;s gland plate inventory costs can be considerable. Furthermore gland production costs are high due to the number of manufacturing operations required to process a given gland. 
   There is a need for a seal gland which is of relatively low cost including the use of material which, after the original manufacturing operation, requires no subsequent machining such as turning, milling or drilling. 
   SUMMARY OF THE INVENTION 
   According to the present invention there is provided a gland plate comprising a rigid disk-shaped element including at least one radially extending wall having a thickness of from 0.1 to 4 mm. 
   Preferably the thickness of the wall is from 1 to 2 mm and more preferably is about 1.5 mm. 
   Preferably set element comprises two axially spaced, radial extending walls. More preferably said element further includes inner and outer circumferential walls extending between said radially extending walls. 
   Preferably the element is a hollow structure. Alternatively the element may be filled with a suitable material such as concrete, plastics or water. 
   Preferably said wall or walls of the elements are made of metal and more preferably said wall or walls are formed by a pressing operation. 
   The gland plate according to the present invention may include a first part providing a first radially extending wall and a second part providing a second radial extending wall, said first radial extending wall being axially spaced from said second radial extending wall. 
   Preferably said first and second parts together provide inner and outer circumferential walls. 
   Preferably the gland plate is provided with one or more through holes, more preferably formed by a pressing or punching operation. 
   Preferably the material displaced when the or each of said holes is being formed provides a strengthening support around said hole. 
   Preferably a gland placed in accordance with the present invention is in the form of a hollow structure having first and second radially extending walls as well as means for feeding fluid through said gland plate. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings are as follows: 
       FIG. 1  shows a cross sectional view of a conventional prior art single cartridge mechanical seal; 
       FIG. 2  shows a cross sectional view of a single cartridge mechanical seal of the invention and  FIG. 2   b  shows an alternate setting clip arrangement; 
       FIG. 3  corresponds to  FIG. 2  and shows a cross sectional view of the gland plate assembly of the invention; 
       FIG. 4  corresponds to  FIGS. 2 and 3  and shows an isometric of the two pressed components which, when assembled, make the gland plate assembly of the invention; 
       FIG. 5  corresponds to  FIG. 4  and shows an exploded isometric view of the two pressed components which, when assembled, make the gland plate assembly of the invention; 
       FIG. 6  shows an alternative single cartridge seal of the invention, showing by way of example only, a different gland plate assembly; 
       FIG. 7  corresponds to  FIG. 6  and/or  FIG. 4  and shows a quarter isometric cutaway of the gland plate assembly of the invention; 
       FIG. 8  illustrates an alternative design of the invention, showing an alternative shaft-sealing device; 
       FIG. 9  illustrates an alternative design of the invention, showing a single component seal arrangement; 
       FIG. 10  illustrates an alternative design of the invention, showing a double cartridge seal arrangement; 
       FIG. 11  illustrates an alternative design of the invention, showing a double component seal arrangement; and 
       FIG. 12  illustrates an alternative design of the invention, showing a gland plate assembly and packing arrangement. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The invention will now be described, by way of examples only, with reference to the accompanying drawings. 
   The conventional prior art single cartridge mechanical seal depicted in  FIG. 1  includes a gland plate  1  which requires a considerable number of machining operations and machine set-ups to allow mating components to be assembled and placed. 
   The total cost of the gland plate  1  is the sum of the machining costs and the costs of the raw material. As illustrated, the raw material of the gland plate  1  in  FIG. 1  is a casting. If the gland plate is manufactured from a solid material, the raw material cost would be lower. However the machining costs are typically considerably more. 
     FIG. 2  shows a single cartridge mechanical seal  4  of the invention. The rotary and axially floating seal face  11  is spring biased towards a static stationary seal face  12 . The rotary seal face  11  is allowed to slide on the static seal face  12 . The interface between the rotary seal face  11  and stationary seal face  12  forms sealing area  13 . This sealing area  13  is the primary seal that prevents the process media  14  from escaping from the process chamber  15 . 
   In addition to the sliding seal face  13 , the process media  14  is sealed by a sleeve elastomer  16  in contact with the shaft  17  and sleeve  18 . This has been termed the first secondary sealing area. 
   The second secondary sealing area is formed between stationary seal face  12  and stationary gland plate assembly  21  using elastomeric member  22 . 
   The third secondary sealing area is formed between the rotary seal face  11  and the sleeve  18  using elastomeric member  24 . 
   The fourth secondary sealing area is formed between the gland plate assembly  21  and the process chamber  15  using gasket  26 . 
   The four secondary sealing areas and the primary sliding sealing interface prevent the process media  14  from escaping from the process chamber  15 . 
   The static seal face  12  is prevented from rotating by radial squeeze between the elastomeric member  22  and the gland plate assembly  21 . An alternative anti-rotation device could be incorporated into the design if so desired. 
   The sleeve  18  is axially terminated adjacent to the clamp ring  23  which contains at least one screw  28  for securing the seal assembly  25  to the shaft  17 . Screw  28  provides rotational drive from shaft  17  to the rotary components in the seal assembly  26 . Rotary seal face holder assembly  26  consists of at least one holder  27 . This holder, preferably metallic in construction, transmits the axial spring  28   a  force to the seal face  11 . 
   Preferably, although not essential, at least one setting clip  29  is used to position the axial and/or radial distance between the rotating clamp ring  23  and gland plate assembly  21 . The latter is provided with an integral annular hook  29   a  for engagement with the setting clip  29 . 
   The setting clip  29  could be either removable using clip screw  5  or, as shown in  FIG. 2   b , setting clip  6  could be a sacrificial wearing member of seal assembly  25 . 
   Sacrificial clip  6  may be of continuous circular construction or split into segments. Since sacrificial clip  6  is a potentially wearing component, it is preferably made from a suitable material such as plastic or brass. Furthermore, if clip  6  has a continuous circular section, it should be sufficiently flexible to allow engagement into the gland clip recess  7 . 
     FIG. 3  corresponds to  FIG. 2  and shows a partial cross section through the gland plate assembly  21 . 
   The gland plate assembly  21  is typically constructed from more than one part. The front plate  30  aligns on at least one feature with the rear plate  31 . Preferably, alignment is made on either the outer radial portion  32  of the front plate  30  or the inner radial portion  33  of the front plate  30 . As shown in  FIG. 3  it is preferable if said location features are both the inner  33  and outer  32  radial portions of the front gland plate  30  since this provides strength to the gland plate assembly  21 . This also provides a surface where an adhesive could be applied. 
   The location features on the front gland plate  30  could be of any shape or size, and/or positioned in the rear gland plate  31 , or positioned on any combination of both front  30  and rear  31  gland plates. 
   Since both front  30  and rear  31  gland plates are manufactured from pressed material steel, preferably a non-corrosive steel material such as stainless steel, the gland plate assembly  21  manufacturing costs are extremely low. 
   The experienced reader will note that pressed sheet steel, of say 1.0 mm 0.040″ to 1.5 mm 0.060″ thickness, can be extremely strong when designed in a manner where the physical shape of the cross section, including the bends in the material, create a rigid structure. 
   From  FIG. 3 , the gland plate assembly  21  has preferably at least one bolt slot  34  which allows the gland plate assembly  21  to be fixed to the process chamber  35  mounting face, using an appropriate screw  36 . 
     FIG. 4  corresponds to  FIG. 3 , and shows an isometric view of the gland plate assembly  21 . The gland plate assembly  21  has preferably four-bolt slots  34  equal spaced which allows it to be fixed to the process chamber. The gland plate assembly  21  is held together both axially and rotationally by at least one crimp indentation  37  in the outer radial surface of the gland plate assembly  21 . It is preferred that said gland plate assembly  21  is further held together by either a suitable adhesive, chemical bond and/or permanent physical operation such as welding. 
   From  FIG. 3 , should the design of the invention be constructed from more than one piece of sheet metal, particularly around the bolt slot area  34 , the slots  38  and  39  in both front  30  and back  31  plates should align with each other. 
     FIG. 5  illustrates an isometric view of the front  30  and back  31  plates, which make up the respective gland plate assembly  21  shown in  FIG. 4 . 
   During the gland plate  30  and  31  manufacturing process, the bolt slots  39  and  38 , are typically formed in the sheet material by a pressing or punching operation. During said operation, the sheet material is displaced  40 . The displaced material  40  surrounding the circumference of the slot  38  and  39  is advantageous as this provides strength to this area of the gland plates  30  and  31 . This is important since at least one screw and the resulting clamping force from the screw is transmitted into this area of the gland plate  30  and  31 . 
   It is deemed to be of further benefit, when at least two gland plates, front  30  and back  31  are utilised in the gland plate assembly  21  as the combined strength is a multiple of the two components. 
   From  FIG. 3 , it is advantageous, although not essential, to allow the axial end  41  of the displaced slots  38  and  39  in the both front  30  and back  31  plates to butt against each other. 
   If both axial ends  41  of the displaced slots butt against each other, the resulting compressive force from screw  36  has to buckle the displaced material surrounding either slot  38  and  39 , particularly if the gland back face is flush against the process chamber face  35 . This butted displaced slot design is therefore very strong and able to withstand compressive loads from screws or bolts acting through the slots  38  and  39 . 
   From  FIG. 3 , it is of further advantage if the front gland plate  130  axially locates against the back gland plate  31  at its outwardly radial and axial position  41  and/or its inwardly radial and axial position  42 . Therefore as compressive force is applied from the screw  36 , the outer and inner most radial portions of the front gland plate  30  gain axial support from the back gland plate  31 . 
     FIG. 6  shows another single cartridge seal design of the invention. The gland plate assembly  50  is extended axially away from the gasket  51  bolting face thereby allowing the stationary seal face  52  and corresponding rotary seal face  53  to be positioned further outboard to that of  FIG. 2 . 
   This offers certain advantages, for example, if a rotary seal face head  53  is radially too large for the rotating equipment seal chamber bore  54 , the design shown in  FIG. 6  allows the rotating seal face head  53  to be positioned in the gland plate assembly  50 . This prevents rotating equipment modifications. 
   Alternatively, if there is insufficient axial room due to an obstruction  56  inside the rotating equipment, the rotating seal face  53  and sleeve  55  can be positioned axially away from the obstruction  56 . This design shown in  FIG. 6  is therefore of considerable benefit. 
     FIG. 7  corresponds to  FIG. 6  and/or  4  and illustrates a quarter cutaway of the gland plate assembly  50 . It will be noted that portions of the gland plate assembly are hollow  57 . 
   Said hollow portions  57  correspond to areas where the strength of the gland plate assembly  50  is deemed not to be critical. Should any region of the gland plate assembly  50 , other than the bolt slot area  58 , require strength or rigidity, then one or more protrusions, indentations, or portions of displaced material could be incorporated adjacent to said region. 
   Referring back to  FIG. 2  the sleeve  18  is preferably a component which may be pressed from sheet steel. While the invention is by no means limited to this, this is a preferred production process in order to maintain a low assembled seal cost price. 
     FIG. 8  of the accompanying drawings illustrates an alternative sleeve  60  and sleeve elastomeric member  61 . 
     FIG. 9  illustrates a single component seal of the invention. The gland plate assembly  70  is of similar shape to the aforementioned figures. However the seal design is a component design rather than a cartridge design which incorporates a sleeve member. This design in  FIG. 9  has fewer components than that of the cartridge seal variant and therefore will be a produced at a lower cost price. 
   The seal of  FIG. 9  includes a pump setting component  71  which axially positions the rotary seal face assembly  72  in terms of the correct spring  73  working length. 
     FIG. 10  shows a double seal  100  version of the invention. Once again the rotary and axially floating seal face  101  is spring biased towards a static stationary seal face  102 . The rotary seal face  101  is allowed to slide on the static seal face  102 . The interface between the rotary seal face  101  and stationary seal face  102  forms a sealing area  103 . This sealing area  103  is the primary seal that prevents the process media  104  from escaping from the process chamber  105 . The other secondary inboard sealing points remain identical in concept to  FIG. 2 . 
   Towards the outboard side of the seal, the outboard rotary and axially floating seal face  118  is spring biased towards a static stationary seal face  119 . The rotary seal face  118  is allowed to slide on the static seal face  119 . The interface between the rotary seal face  118  and stationary seal face  119  forms sealing area  120 . This outboard sealing area  120  is the primary seal that prevents the barrier media  121  from escaping from the barrier chamber  114 . The barrier media  121  is also sealed at the inboard side of the assembly, by sealing area  103 . 
   At the outboard side, the secondary sealing areas include elastomeric member  117  and elastomers  137  and  138 . 
   Once again the static outboard seal face  119  is prevented from rotating by the frictional drive of elastomeric member  117  against gland  122 . The gland could incorporate an alternate anti-rotation drive mechanism such as a pressed lug, or a pin and slot arrangement. 
   An intermediate component  123  is positioned between the two stationary seal faces  102  and  119 . Said intermediate component  123  is preferably manufactured from a press steel plate of thin thickness. In an alternative embodiment, this intermediate component  123  is a machined item. 
   The gland plate assembly  124  is manufactured from three, pressed, preferably sheet steel, components. This assembly  124  is designed in such a way as to eliminate or limit subsequent conventional machining operations.  FIG. 10  therefore illustrates that the invention is not limited to a particular number of pressed sheet steel components which make up the gland plate assembly. Sufficiently to state one or more pressed steel components are positioned in such a way to provide the gland plate assembly with strength at a low manufacturing cost. 
   Barrier media  121  enters insertion hole  125 . Preferably a corresponding insertion hole is punched through the gland plate assembly  124  and sealed by rubber washers  127  and  128 , if necessary, at either side of the insertion hole  126 . 
   Barrier media  121  enters the barrier chamber  114  preferably via a plastic tube  129  inserted through a rubber washer  127  and  128  and fitting  130  arrangement. This provides a pressure tight and leak tight, leak tight joint. Said barrier fluid  121  lubricates and cools seal faces  120  and  103  and is evacuated via a similar hole and tube arrangement positioned at another place in the gland plate assembly  124 . 
   Thus, it can be seen that pipe  129  and fitting assembly  130  have been incorporated into the hollow cavity  131  of the gland plate assembly  124 . 
   Fittings  130  are preferably of “panel” type construction which are ideal for creating a pressure tight, leak free seal in a thin sheet metal construction such as the gland plate assembly  124 . 
   Panel fittings  130  and  132  are fitted to the punched holes  126  and  133 . A pipe  129  connects said fittings,  130  and  132  providing a pressure tight joint. Pipe  129  is preferably a plastic tube. Fittings  130  and  132  preferably accommodate said plastic pipe  129  with a “push-fit”, leak tight seal. The invention is not limited to the use of this pipe  129  and fitting  130  and  132  construction. However such a construction is a particular low cost option. 
   The fitting and pipe assembly  134  is typically installed prior to assembling the rear gland plate flange  135  to the front gland plate flange  136 . The front gland plate  136  has an opening, which correspond, to the fitting position in the rear gland plate  135 , thereby allowing the joining of both flanges which create the gland plate assembly  124 . 
     FIG. 11  illustrates a double component seal of the invention. The gland plate assembly  140  is of similar shape to the aforementioned figures. However the seal design is a component design rather than a cartridge design which incorporates a sleeve member. 
   Gland plates of the invention may be employed for both rotary seals and stationary seals, single, double or triple mechanical seals, whether designed in a cartridge or component seal format. 
   Furthermore, the design could be used for both pressurised and non-pressurised barrier fluid systems. 
   The invention may be used with metallic components as well as non-metallic components such as plastic. Some types of equipment rotate the housing and have a stationary shaft. It is considered that the invention can be similarly applied to such designs. 
     FIG. 12  illustrates that, the gland plate assembly  150  of the invention is by no means limited for the use of a mechanical seal. Rotating equipment is often sealed by other means such as packing  151 . 
   Packing is a traditional manner of sealing rotating equipment at a low cost. The gland plate assembly  150  of the invention is therefore particularly suited for this type of sealing since this too is a low cost option. 
   As shown in  FIG. 12 , the gland plate assembly  150  can be adopted to transmit the compressive forces from at least one screw  152  to the packing  151 . This thereby creates a seal between the stationary process chamber  153  and rotating shaft  154 . 
   In summary, the invention provides a gland plate assembly which comprises one or more components manufactured from a relatively thin material, said material formed into a shape which is sufficiently rigid to hold a stationary member which may subsequently slide relative to a corresponding rotary member or may be, for instance, a packaging member which creates a seal between a stationary member and a rotating member. In general, no subsequent machining operations are required after the gland plate forming operation. The assembly may be of modular construction thereby permitting its use in more than one sealing arrangement. 
   The components of the gland plate assembly may be mechanically, and/or chemically, and/or thermally connected together in a non-detachable method. The components of the gland plate assembly are located relative to one another by at least one location member, said location member being an integral part of at least one of the former components. Alternatively, the location member is a separate part to any of the former components. 
   A gland plate assembly of the invention may contain at least one fitting, which connects two regions of the mechanical seal, allowing a fluid to be passed between the two regions The fitting, including a connecting pipe, may be positioned in the hollow cavity created by at least two components which comprise the gland plate assembly.