Abstract:
A hydraulic sample mounting press utilizes a face seal against the top face of a molding cylinder. The face seal employs a hydraulic cylinder to press a disk-shaped surface of a cap piece against the top annular face of the mold cylinder for a metallographic mounting press. The face seal cylinder is mounted to a hydraulic fluid column that allows the face seal to rotate away from the mold cylinder for access to the molding cylinder and to rotate into place when a metallographic mount is to be molded.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims priority under 35 U.S.C. § 119(e) on U.S. Provisional Application No. 60/285,674 entitled SAMPLE MOUNTING PRESS, filed on Apr. 23, 2001, by Cox et al., the entire disclosure of which is incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   The present invention relates to a mounting press for metallographic samples and particularly to an improved seal structure for the molding chamber. 
   Mounting presses are employed to mold a thermoplastic or thermosetting material around typically a metallic specimen for ease of handling in subsequent polishing and analyzing processes. Such mounting presses include a cylindrical mold chamber into which an upper closure ram and a lower hydraulically driven ram extend, such that the molding material and sample are held and compressed between the rams. 
   The standard upper closure ram uses a handle to move a radially sealing upper ram into the bore of the molding cylinder at the top. This mechanism is then locked into place with a quarter turn, bayonet-type device or by using coarse threads. This style of enclosure requires considerable manipulation by the operator especially if they have to turn the mechanism to engage threads. Opening of this type of closure is also difficult since, during the molding process, pressure builds up between the lower ram and the removable, upper closure ram of the mold cylinder. This pressure on the quarter turn device or the threads makes it very difficult for the user to spin the mechanism open. Regularly a length of pipe or some other type of lever must be used to gain a mechanical advantage to open the mold cylinder. Also, blowby flashing tends to make the upper closure ram stick within the mold cylinder. Once open, any residual material or “flashing” left on the upper ram of the closure device must be cleaned prior to sliding the upper ram back into the bore of the mold cylinder. 
   SUMMARY OF THE INVENTION 
   The invention is a departure from such traditional mounting press enclosure systems. The hydraulic enclosure system of this invention avoids the cumbersome radial seal altogether and instead utilizes a face seal which engages the top face of the mold cylinder. This face seal is actuated by a hydraulic cylinder which presses a sealing cap piece against a top annular sealing face of the mold cylinder. When this cap piece has formed a face seal, the metallographic mount is molded. When the face seal is removed, the internal pressure of the mold is immediately released and an upper enclosure containing the cap piece is readily moved away from the mold cylinder to expose a mount and specimen contained therein for fast, easy removal. In a preferred embodiment, the hydraulic cylinder and cap piece is mounted to a cylindrical column that allows it to rotate away from the mold cylinder when the mount is complete and rotate into place when a mount is to be made. The column that acts as the rotational device also delivers the hydraulic fluid to the upper hydraulic cylinder so there is no need for a hose or other hydraulic connection. Also, the cap piece and top face of the mold cylinder do not need to be cleaned between mounts. This enclosure system also allows the workable height of the system to be lower and makes it more accommodating for the operator since it minimizes user interaction with the mold process and prevents user exposure to hot mechanism. Further, the hydraulic system in one embodiment combines the hydraulic cylinders, manifold, valving, pump, reservoir, transducers, rotary seal, and accumulator into one assembly eliminating hydraulic hoses and fittings between components, which virtually eliminates hydraulic leak potential. 
   These and other features, objects and advantages of the present invention will become apparent upon reading the following description thereof together with reference to the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a sample mounting press embodying the present invention; 
       FIG. 2  is a fragmentary right-side perspective view of the upper pivoted section of the assembly shown in  FIG. 1 , shown with the upper face sealing cylinder pivoted to a position exposing the mold cylinder assembly and showing a metallographic molded sample in position for removal therefrom; 
       FIG. 3  is a side elevational view of the sample mounting press; 
       FIG. 4  is an exploded perspective view of the face seal assembly; 
       FIG. 5  is a perspective view of the mold cavity subassembly; 
       FIG. 6  is an exploded lower perspective view of the structure shown in  FIG. 5 ; 
       FIG. 7  is an exploded perspective view of the pivoted hydraulic supply cylinder seen also in  FIG. 3 ; 
       FIG. 8  is a fragmentary vertical cross-sectional view of the sample mounting press; and 
       FIG. 9  is a perspective view of the mold adapter block shown in  FIGS. 3 and 8 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring initially to  FIG. 1 , there is shown a sample mounting press  10  embodying the present invention which comprises a lower cabinet  12  housing a keypad  14  and display  16  for the operation of the unit. Mounted within cabinet  12  is the mold cylinder assembly  30  ( FIGS. 3 ,  5  and  8 ) and a lower ram assembly including a mold adapter block  40 , a hydraulic cylinder  84 , and a manifold  42  coupled to a hydraulic pump  41  providing a hydraulic fluid system pressure of approximately 3000 pounds for operation of the various hydraulic cylinders employed in the system. 
   Pivotally mounted with respect to cabinet  12  is an upper face seal assembly  20  ( FIGS. 3 ,  4 , and  8 ) which, as seen in  FIGS. 1 and 2 , is mounted in an upper enclosure  18  which can pivot to the left (shown by arrow A in  FIG. 1 ) to expose the top sealing face plate  31  of the mold cylinder assembly  30 , shown in detail in  FIGS. 5 and 6 . This exposes the cylindrical mold cavity  32  to allow the operator to remove the metallographic sample encapsulated in a molding material as a unit in disk-shaped sample mount  17  ( FIG. 2 ) as described below. 
   The upper face seal assembly  20  is shown in  FIG. 4  and includes a pancake hydraulic cylinder  25  which is coupled by a thermal gasket  26  and fasteners  22  to a cylindrical flange  24  with the completed assembly shown in  FIG. 3 . Cylinder  25  includes a movable piston rod  23  ( FIG. 8 ) having an enlarged end over which the sealing cap piece  27  extends via an undercut slot  29  ( FIG. 4 ). Metal cap  27  is rigid and defines a rigid face seal  28  which sealably engages the top annular sealing surface  31  of mold cylinder assembly  30 , as best seen in  FIG. 8 . Flange  24  also includes an undercut slot  21  ( FIG. 4 ) which defines a shoulder  21 ′ that lockably engages circular flange  34  of mold assembly  30  (as also best seen in  FIG. 8 ) to lock the face seal assembly  20  to the mold assembly  30  during the molding process. Thus, semi-annular shoulder  21 ′ ( FIG. 4 ) circumscribes an arc which is open sufficiently such that cylindrical flange  34  can be received within slot  21 . When closed as seen in  FIG. 8 , the upper surface of shoulder  21 ′ engages the lower surface  35  of the flange  34  of the mold assembly  30  to lock the face seal assembly to the upper end of the mold cavity, thereby allowing the sealing pressure to be applied to effect the face seal by cylinder  25 . 
   The pancake hydraulic cylinder  25  is sealably coupled to a cylindrical column or pressure rotary coupling  50  ( FIGS. 7 and 8 ), which receives pressurized hydraulic fluid from pump  41  via manifold  42 . The pressure rotary coupling  50  has a generally cylindrical body  52  with a central bore  54  therein capped by sealing cap  56  at its upper end. A radially extending opening  55  is sealably coupled to the input  25 ′ of pancake cylinder  25  by means of an O-ring sealing gasket  56 ′, as best seen in  FIG. 8 . The lower end of pressure rotary coupling  50  is rotatably mounted within a mounting plate  60  by means of a sleeve bearing  62 . Hydraulic pressure is applied to the cylindrical bore of rotary coupling  50  at its lower end from manifold  42  via port  43  ( FIG. 8 ). Suitable valves are provided to selectively apply pressure during the sealing and molding process in a conventional manner. The lower end  57  of rotary coupling  50  is sealably mounted within the bushing  52  and block  60  by means of an O-ring seal  58  and back up ring seal  59  ( FIGS. 7 and 8 ), which allows rotation of the upper seal assembly  20  coupled to rotary coupling  50  between a closed position, as shown in  FIGS. 1 and 8 , and an open position, shown in  FIG. 2 , by the rotation of rotary coupling  50  with respect to the fixed mounting block  60 . Rotary coupling  50  is held in block  60  by an annular flange  57  integral with the body  52  of the rotary coupling and an annular clamp  64  ( FIG. 8 ) secured to block  60 , in turn, suitably secured within cabinet  12 . 
   Mold cylinder assembly  30  ( FIGS. 5 and 6 ) includes four cartridge heaters  33  ( FIG. 6 ) positioned in radially spaced relationship around the peripheral of the cylindrical body  36  of the mold assembly  30 , which is conventionally surrounded by a cylindrical water jacket  37  sealed by pairs of spaced O-rings  38 . A thermocouple  33 ′ is also inserted into the body  36  of mold cylinder assembly  30  and is employed in connection with a control circuit to provide the desired molding temperature within the cylindrical mold cavity  32  by heaters  33  during the molding process. The mold cylinder assembly  30  includes four radially outwardly extending arcuate flanges  44  spaced at approximately 90° intervals and circumscribing an arc of about 30° to 40° to interlock with the lower mounting block  40 , as seen in  FIG. 8 . Block  40 , as best seen in  FIG. 9 , includes a base plate  41  which is bolted by bolts  42  ( FIG. 3 ) extending into through apertures  47  into the top of hydraulic cylinder  84 . Cylinder  84  includes a piston  85 , as seen in  FIG. 8 , extending upwardly and which is captively held with its enlarged head  86  fitted within an undercut open slot  87  in a lower ram  88  enclosing the lower end of cylindrical mold chamber  32 . The mounting block  40  includes four upwardly extending shoulders  48 , each of which include an undercut  45  which defines shoulders  46 . The arcuate shoulders  46  are spaced at 90° intervals with slots  49  extending between adjacent shoulders  46  to allow the insertion of flanges  44  therein to bayonet-lock mold assembly  30  to block  40 . Shoulders  46  engage and lock flanges  44  of mold assembly  30  into locked engagement with cylinder  84 , such that pressure can be applied to the lower end of the cylindrical mold chamber  32  by ram  88  when actuated by hydraulic pressure from manifold  42  coupled to cylinder  84  by a suitable valve. Hydraulic cylinder  84  is actuated at approximately 3000 psi system pressure during an operating cycle to extend ram  88  upwardly into the chamber  32  of cylindrical mold assembly  30  while the top surface  31  of the mold chamber is sealed by the face seal  28  to compress the polymeric thermosetting material around and onto a metallographic specimen. 
   During a cycle of operation, the upper assembly  18  is opened to the position shown in  FIG. 2 , and ram  88  is raised by the actuation of cylinder  84  to present the top disk-shaped surface  89  of ram  88  to an operator for placing a metallographic sample thereon. Subsequently, cylinder rod  85  and ram  88  are retracted slightly into the cylindrical mold cavity  32  of mold body  36 . Resin is then placed into the mold cavity  32 , and the upper assembly  18  pivoted using rotary coupling  50  to a closed locked position. The pancake hydraulic cylinder  25  is then actuated to form the face seal at the upper end of the mold chamber  32 . Heat and pressure is then applied to the molding material by heaters  33  and compression through lower cylinder  84  to the thermosetting material for a predetermined period of time sufficient to mold the material around the metallographic sample. A conventional thermosetting or thermoplastic resin into which the metallographic sample is encapsulated is melted under an internal mold pressure of from about 2000 psi to about 4200 psi at about 300° F. The molding process takes from 6 to 20 minutes depending upon the material employed, which may include polycarbonate, phenolics, epoxies, or other resins typically employed for molding metallographic samples for use in metallographic analysis equipment. After the heating and pressure steps, mold assembly  30  is cooled either using water applied to the water jacket  37  for cooling the chamber or, in the case of thermoplastic resin, it is air cooled. The pressure on cylinders  25  and  84  is then released by suitable valving to allow the upper unit  18  to again pivot to an open position. The metallographic sample disk-shaped mount  17  is removed from the device by again applying some hydraulic pressure to cylinder  84  to eject the mount  17 , as seen in  FIG. 2 . By providing a face seal which is readily moved away from the mold chamber and by activating cylinder  84 , the disk-shaped mount is pushed out of the cylindrical mold chamber  32 , and the prior art difficulties with opening the upper end of the mold cavity is eliminated through the use of the face seal  28 . The body of the mold cavity and the cap piece forming the face seal can be made of metals typically used for sample mounting presses, such as stainless steel, aluminum alloys, or the like. The sealing surfaces  28  and  31  of the respective members are polished to form a leak-free seal when cylinder  25  is actuated by a pressure of about 3000 psi. 
   It will become apparent to those skilled in the art that various modifications to the preferred embodiment of the invention as described herein can be made without departing from the spirit or scope of the invention as defined by the appended claims.