Abstract:
An apparatus ( 10 ) for manufacturing rubber-based spiral wound gaskets,in which a length of an elongate band ( 22 ) passes through a bath ( 34 ) for applying a coating of a rubber sealing material and then is wound in overlapping relation on a die ( 100 ) to make a spiral wound gasket. Wire brushes ( 70 ) remove the rubber sealing material from selected portions of the band, to define interior and exterior diameter portions of the wound gaskets. The die ( 100 ) defines a slot ( 102 ) extending inwardly from a perimeter for receiving a distal end portion of the elongate band ( 22 ) so that the gasket does not unwind. A fixing device ( 120 ) secures selected portions of the wound elongate band together at the interior and exterior diameters. A cutter ( 90 ) severs the elongate band ( 22 ) in order to remove the spiral wound gasket from the apparatus ( 10 ). A tapper ( 134 ) moves strikingly against a perimeter portion of the die to dislodge the spiral wound gasket. A method is disclosed that winds the elongate band around the perimeter of the die ( 100 ) until a desired radially thick spiral wound gasket is formed.

Description:
TECHNICAL FIELD 
     The present application relates to gasket manufacturing apparatus and processes. More particularly, the present invention is directed to apparatus and methods for manufacturing rubber spiral wound gaskets. 
     BACKGROUND OF THE INVENTION 
     Spiral wound gaskets made of rubber-derivative materials are used typically for oil seal connections in industrial processing applications. The rubber-based spiral wound gaskets are typically formed by rolling a thin sheet of rubber material in overlapping relation to form a tube. The overlapping layers of the rubber sheet define the radially-thick gasket having an inner diameter and an outer diameter for being received in a sealing application. A cross-section is cut through the tube to form a disc-like gasket of a selected thickness, having the selected inner diameter and outer diameter. The disc is pressed in a mold having an inner and outer diameter lip material for sealing. A primer encapsulates the windings of the rubber material with the lip material. 
     While these processes have resulted in rubber-based gaskets suitable for oil sealing and other applications, there are drawbacks to the apparatus and methods of manufacturing such gaskets. It is cumbersome to hold the sheet while rollingly winding the sheet into a tube. The tube must be held rolled while gaskets are cut, and the cut gaskets also must be held from unwinding. Further, the tube often can not be completely cut to form gaskets. The ends loosen and generally a portion of the tube must be scrapped. 
     Accordingly, there is a need in the art for an improved method and apparatus for manufacture for rubber-based spiral wound gaskets. It to such that the present invention is directed. 
     BRIEF DESCRIPTION OF THE PRESENT INVENTION 
     The present invention provides an apparatus and method for manufacturing rubber-based spiral wound gaskets. The apparatus for making a spiral wound gasket comprises a feeder that communicates a length of an elongate band for winding in overlapping relation to make a spiral wound gasket. The elongate band passes through a fluidial bath of a sealing material whereby the elongate band becomes enclosed within a jacket of the sealing material. A rotatable die defining a slot extending inwardly from a perimeter of the die receives a distal end portion of the elongate band, for winding around the perimeter of the die a length of the elongate band including the jacketed portion thereof. The apparatus provides a fixing device for securing selected portions of the wound elongate band together and a cutter for severing the elongate band, whereby the spiral wound gasket made with the length of the elongate band is separable from the apparatus. A tapper movable from a first position in alignment with a perimeter portion of the die to a second position striking forcibly against the perimeter portion of the die selectively dislodges the spiral wound gasket. The elongate band, being engaged to the die by the distal end portion of the elongate band being received in the slot, is wound around the perimeter of the die until a desired radially thick spiral wound gasket is formed and upon being secured together by the fixing device, the cutter operating to sever the elongate band and the tapper striking the perimeter portion of the die to dislodge the spiral wound gasket therefrom. 
     In another aspect, the present invention provides a method for manufacturing a rubber-based spiral wound gasket, comprising the steps of: 
     (a) receiving in a slot extending inwardly from a perimeter edge of a die a distal end portion of an elongate band having at least a length portion jacketed by a rubbery sealing material; 
     (b) winding a length of the jacketed elongate band around the perimeter of the die; and 
     (c) fixing selected portions of the wound elongate band together to form a rubber based spiral wound gasket. 
    
    
     Objects, features, and advantages of the present invention will become apparent from a reading of the following detailed description of the invention and claims in view of the appended drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 illustrates in perspective schematic view an apparatus according to the present invention for manufacturing spiral wound gaskets. 
     FIG. 2 is a side elevational view of a gasket forming section of the apparatus illustrated in FIG.  1 . 
     FIG. 3 is a cross-sectional view of a elongated band jacketed with the sealing material by the apparatus illustrated in FIG.  1 . 
     FIG. 4 is a cross-sectional view taken along line  4 — 4  of FIG. 1 illustrating the gasket formed on the die in the gasket forming section of the apparatus illustrated in FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now in more detail to the drawings, in which like numerals indicate like parts throughout the several views, FIG. 1 is a perspective schematic view of an apparatus  10  for manufacturing rubber-based spiral wound gaskets according to the present invention. The apparatus  10  includes a band supply section  12 , a gasket forming section generally  14 , and a gasket discharge section  16 . 
     The band supply section  12  includes a supply  20  of an elongate band  22 . In a preferred embodiment, the elongate band  22  is a narrow fiber web. The band  22  passes between a pair of opposing guide rollers  24 . 
     Adjacent the guide rollers  24  is a housing  30  for a sealing material bath  34  that holds a fluidial mixture of a sealing material to be coated onto the elongate band. The sealing material is preferably rubber-based. Spaced-apart rollers  38 ,  40 , and  42  guide the elongate band into and through the solution contained within the bath  34  for coating with the sealing material. The sealing material dries rapidly upon the continued travel of the elongate band out of the bath  34 . A return roller  44  in the housing  30  directs the elongate band  22  to an outlet  46 . 
     In an alternate embodiment, the sealing material is applied by passing the elongate band past a plurality of spray nozzles that communicate with a supply of the sealing material. The spray nozzles are selectively actuated to apply sealing material to at least a length of the elongate band. 
     A pair of pivotally mounted wire brushes  70  are disposed on opposing sides of the travel path for the elongate band  22  near the exit from the housing  30 . The wire brushes  70  mount on pivotable bases  72  in order to move from a first position spaced-apart from the elongate band  22  to a second position with the wire brushes  70  in contact with the respective face of the elongate band. The wire brushes  70  are rotatable such as by a pneumatic motor  74  which rotates the shaft on which the wire brushes  70  mount. 
     A treatment station  75  includes spray nozzles  76  which communicate with a supply of a treating solution. A tray  77  collects the overspray. The sprayer  76  in the treatment section  75  applies a spray coating to the jacketed portion of the elongate band. In a preferred embodiment, the spray is an acid bath to provide increased temperature range for the gasket having the jacket of a rubber sealing material. The treatment solution is selected from the group of phosphoric acid, aluminum hydroxide, silicone carbonate, and boron. 
     An idler arm  80  connects by a pivot  82  to the frame for the apparatus  10 . The arm  80  is biased by a spring. A roller  86  attaches to a laterally extending distal portion of the arm  80 . The roller  86  guides the band  22  into a cutter assembly  90 . 
     The cutter assembly  90  mounts to a movable frame  92 . The frame  92  moves from a retracted position to an extended position as operated by a motor-driven screw assembly  93 . The cutter  90  includes a pivotable knife  94 . The knife  94  moves from a first position away from an opening in the cutter assembly  90  to a cutting position whereby the band  22  passing through the opening is severed. A table  96  reciprocally mounts to the cutter assembly  90 . The table  96  moves between a first position adjacent the cutter assembly  90  and a second position spaced-apart from the cutter assembly. In the first position, the table  96  firmly bears against the band  22  in the cutter assembly  90  to hold the band secure during the cutting operation of the knife  94 . The table  96  drops to the second position during the winding process for forming the spiral wound gasket of the present invention, as discussed below. 
     The gasket forming section  14  includes a rotatable die  100 . The die  100  in the illustrated embodiment is an annular disc in which at least one slot  102  is formed. The slot extends inwardly from a perimeter edge  104  of the die  100 . The perimeter edge  104  conforms in cross sectional shape to the surface defined by the crimp rollers  24  whereby the metal band  22  is matingly held to the perimeter edge  104  of the die  100 . A tracking roller  106  mounts to a frame  108  that is spring biased to a support column  110 . The support column includes a potentiometer  112  to measure the movement of the support frame  108  in the support column  110 . 
     A welding apparatus  120  is disposed opposing the tracking roller  106 . The welding apparatus  120  connects to a reciprocal member  122  in order to move the welding apparatus  120  from a first position spaced-apart from the die  100  to a second position in which a pair of welding members  124  are in contact with portions of the elongate band  22  on the die  100 . The welding members  124  provide for securing positions of elongate band together, such as by sonic welding, adhesive, hot contact securing, and other suitable rapid securing mechanisms. 
     The gasket discharge section  16  includes a tapping apparatus  130 . The tapping apparatus  130  has a pneumatic cylinder  132  from which a piston extends and retracts. A tapper  134  attaches to the distal end of the piston of the cylinder  132 . In the illustrated embodiment, the tapper  136  is a bronze disc. The cylinder  132  mounts to an arm  136  that encloses, a screw rod  138 . The screw rod  138  attaches to the end of the arm  136 . The opposing end of the screw rod  138  defines a roller  140 . A motor  142  connects to a driver roller  146 . A belt  148  extends between the driver roller  146  and the roller  140 . 
     FIG. 3 is a cross-sectional view of the elongate band  22  after exiting the sealing material housing  30 . The elongate band  22  is enclosed in a jacket  180  of the rubber sealing material with opposing thick regions generally  182 ,  184  on the side faces of the band  22  and opposing thin regions  186 ,  188  on the relatively thin sides of the band  22 . 
     FIG. 2 is a partial view of the gasket forming section  14  showing details of the gasket formed on the die  100  in the forming section  14 . The die  100  is illustrated with a plurality of turns of the coated elongate band  22  wound around the perimeter  104  to form the gasket according to the present invention. The welding apparatus  120  is illustrated spaced-apart from the radially thick cross-sectional view of the gasket, prior to moving into position for securing portions of the elongate band  22  together. 
     With reference to FIG. 1, the apparatus  10  of the present invention is operated in order to form a spiral wound gasket. The roll of the narrow thin elongate band  22  is attached to a rotatable mandrel in the band supply section  12  to provide a supply of the elongate band for winding into the spiral wound gasket. The elongate band  22  feeds through the opposing guide rollers  24  over the rollers  38 ,  40  and passes through a cleaner bath solution held in the bath  32 . The cleaner solution removes the contaminants, such as oils and other materials left on the elongate band  22  during manufacturing. The rubber-based sealing material is then applied to the elongate band  22 . The band  22 , guided by the rollers  42 , passes into the bath  34  for application of the rubber-based sealing material held in the bath. The coated band  22  passes over the roller  44  and the roller  48  and exits from the housing  30  through the opening  46 . 
     At the treatment station  75 , the spray nozzle  76  communicates the treating solution to the jacketed elongated band  22  overspray collects in the tray  77 . 
     Periodically, the wire brushes  70  are pivoted from the spaced-apart position to the contact position whereby the wire brushes  70  are brought into contact with the jacketed elongate band  22 . The motors  74  operate in order to rotate the wire brushes  70  which bear against the opposing broad faces of the elongate band  22 . The wire brushes remove the rubber jacket  180  from the portion of the elongate band  22  on which the brushes are brought into contact. The purpose of removing the rubber sealing material from a portion of the elongate band  22  is to provide band surfaces for welding and for being exposed on the inner diameter and outer diameter of the completed spiral wound gasket, as discussed below. The elongate band  22  passes under the idler roller  86  attached to the idler arm  80 . The elongate band  22  is held in the cutter assembly  90 . The table  96  reciprocates from the first position to the second position bearing the elongate band against the cutter assembly  90 . In the spaced-apart position of the table  96  the elongate band  22  is spaced apart from the cutter assembly  90 , as discussed below. 
     With reference to FIG. 2, the cutter assembly  90  moves between the retracted position whereby the cutter assembly  90  is spaced-apart from the die  100  and the extended position in which the cutter assembly  90  is brought close to the perimeter edge  104  of the die  100 . In this position, the elongate band  22  is held between the table  96  and the cutter assembly  94 . A distal portion  180  of the band  22  is fed into the slot  108  in the disc  100 . The disc  100  is rotated in order to start winding the elongate band  22  about the perimeter  104  of the die  100 . As the initial portion of the elongate band reaches the tracking roller  106 , the table  96  is released and drops to the second spaced-apart position. The idler arm  80  moves downwardly as the table  96  moves downwardly. The table  96  moves out of the way, and the roller  92  guides the travel of the elongate band  22  as it moves longitudinally towards the die  100 . 
     The apparatus  10  is configured whereby the elongate band  22  defines a tangent to the die  100 , in order to avoid bending the elongate band  22  as it wraps around the perimeter  104  of the die. One and one half revolutions of the die  100  are made. The die  100  stops rotating. The welding apparatus  120  moves from its retracted position to the engagement position placing the welding tips  124  against the elongate band  22  opposing the tracker roller  106 . The welding apparatus  120  is operated to secure the overlapping band  22  together. In the illustrated embodiment, the welding tips  124  are electrodes. An electric current communicated between the electrodes through the metal elongate band  22  spot welds the outer wrap to the inner wrap. The welding apparatus  120  then moves to its retracted position spaced apart from the die  100 . The die  100  resumes rotating in order to wind a plurality of overlapping layers of the elongate band onto the die  100  and thereby form a radially increasing thickness of a gasket. 
     The tracker roller  106  is biased to the support column  110 . The potentiometer  112  measures the change in the position of the tracker roller  106  relative to the support column  110 . This provides a measure of the increasing radial thickness of the spiral wound gasket being formed on the die  100 . At an appropriate time, depending on the outer diameter of the gasket being formed, the wire brushes  70  are pivoted from the retracted position to a position where the wire brushes bear against the wide faces of the elongate band  22 . The wire brushes  70  are rotated by the motors  74  in order to brush away the rubber sealing material covering a portion of the elongate band  22 . The length of the portion for which the jacket  180  is removed is a length sufficient to provide at least one and a half ending wraps of the elongate band around the gasket being formed, as well as to provide one and a half leading wraps of the elongate band  22  for the next gasket to be formed. It is to appreciated that this portion includes the short distal portion  180  received in the slot  108 . 
     When the final one and a half wraps of the unjacketed elongate band  22  are made, the rotation of the die  100  stops. The welding apparatus  120  moves from the retracted position to a contacting position with the welding tips  124  in contact with the exterior surface of the elongate band on the die  100 . The welding apparatus  120  is actuated to spot weld the distal end of the gasket being formed on the die  100 . The welding apparatus  120  then retracts. 
     The motor  142  is operated to drive the belt  148  so that the screw  138  rotates. This moves the arm  136  laterally towards an alignment position relative to the die  100 . When the tapper  134  is aligned with an arcuate portion of the die  100  and the gasket wrapped around the perimeter edge  104 , the motor  142  stops. The table  96  moves to its elevated position in order to hold the elongate band  22  firmly in the cutter assembly  90 . The knife  94  is pivoted to sever the gasket on the die  100  from the supply of the elongate band  22 . 
     The pneumatic cylinder  132  is actuated to drive the tapper  134  strikingly against the side face of the die  100 . The tapper  134  bears forcingly against the die  100  and the gasket formed thereon, and this sharp hit taps the gasket free of the die  100 . 
     The pneumatic cylinder  132  then retracts the tapper  134 . The motor  142  is reversed to move the arm  136  from its extended position to the retracted position spaced apart from the die  100 . 
     FIG. 4 illustrates a cross-sectional view of the gasket  190  made with the apparatus  10 . The gasket  190  defines an inner face  192  on the inner diameter of the gasket  190  and an outer face  194  on the outer diameter of the gasket. An inner portion  196  has a wrap and a half of the unjacketed band  22 . Similarly, an outer diameter portion  198  has a wrap and a half of the unjacketed band  22 . The wraps for the inner portion  196  and the wraps for the outer portion  198  are each secured by welds to hold the gasket together. An intermediate section  200  includes a plurality of turns of the jacketed elongate band  22 . As the band  22  is wound around the perimeter of the die  100 , the rubber sealing material in the opposing high density regions generally  122 ,  184  become more densely packed. The low density regions  186 ,  188 , however, do not become more densely packed as the winding continues to form the gasket. Accordingly, the resulting gasket has opposing faces  202 ,  204  of a low-density sealing material which contact the faces of the flange in the connection being sealed. The low density provides a relatively low minimum seat to affect the seal. The high density sealing material  182 ,  184 , allow the gasket to resist interbuckling. The rubber-based spiral wound gasket can subsequently be placed in a mold with an inner diameter core and an outer diameter wrap and encapsulated in a covering material, if desired. The core and the wrap are especially selected for the service tasks required these surfaces. 
     The present invention accordingly provides an apparatus and method for forming improved rubber-based spiral wound gaskets. The principles, preferred embodiments, and modes of operation of the present invention have been described in the foregoing specification. The invention is not to be construed as limited to the particular forms disclosed because these are regarded as illustrative rather than restrictive. Moreover, variations and changes may be made by those skilled in the art without departure from the spirit of the invention as described by the following claims.