US1499132A - Electric pneumatic casting machine - Google Patents

Description

June 24 1924.

C. S. VAN HORN ELECTRIC PNEUMATIC CASTING MACHINE 2 Sheets-Sheet 1 Filed Ju ly 27, 1920 June 24 1924. 1,499,132

C. s. VAN HQRN ELECTRIC PNEUMATIC CASTING MACHINE Fil d u y 27. 1920 2 Sheets-Sheet? Patented June 24', 1924.

TED STATES,

1,499,132 PATNT orrics;

CHRIS s. VAN HORN, or BLOOMSBURG, PENNSYLVANIA.

ELECTRIC PNEUMATJEC CASTING MACHINE.

Application filed July 27,

' paratus used iii-connection with my process for producing dental inlays of exact dimensions.

Up to the present time, no apparatus has been devised for the accurate casting of dental inlays, that is, dental castings of the same marginal dimensions as the wax pattern in the tooth. The methods and apparatus now in use are at best, only approximate, mainly because no cognizance is taken of the fact that the materials which enter into thecasting operation, such as the gold, the investment materials, and the pattern waxes, are subject to the physical law of expansion and contraction upon the appli-- cation and withdrawal of heat, each such substance having its individual coefficient under varying thermal influence.

For instance, in all known processes, no exact allowance has been made for any change in size in the wax pattern occurring in transferring it from the mouth to the investment. Pattern wax is very susceptible to the physical effect of heat, a rise or fall of a few degrees in temperature during the hardening or setting of the investment involving' the pattern, means a corresponding change in the size of the wax mass and consequently the casting cavity or mold. So also, during the drying out and burning'out operations the investment expands when heated to such high temperatures as 1,000 F., which expansion produces a corresponding increase in the size of the casting cavity. An accurate process demands not only that the investing apparatus used be capable of not only imparting through the plastic investment a given temperature to the wax pattern during the investment and maintaining this definite temperature until the investment is thoroughly hardened, but also that the casting apparatus be capable of imparting to the investment which forms the casting mold, a predetermined elevated tem- 1920. Serial No. 399,365.

perature whereby to slightly enlarge and maintain at such size, the casting cavity in the investment during the drying out, burning out, and even during the initial portion 1 of the actual casting operation. This temperature regulation must be accurate, and at all times under the absolute control of the operator.

To make a gold casting of the same marginal dimensions or size as the wax pattern, when the latter is in the tooth cavity in the mouth, the wax pattern must be invested at a temperature sufficiently above tooth cavity temperature (which is approximately 95 F.) to compensate for the shrinkage in the gold casting during its cooling.

Present pattern waxes of the best quality can not be safely expanded in excess of about two per cent without melting or dulling delicate or sharp margins of the pattern, and investing materials of the best quality have a maximum expansion of 0.85 per cent at around 1000 F. Above this they shrink that is, burn smaller, and if permitted to cool down from 900 to 70 F., they shrink, and the mold is smaller than when the investment set. On the other hand, the total shrinkage in 24 K. gold is around 3.84 per cent, which can be partly controlled by pressure, when casting, but the uncontrollable shrinkage in gold when cast under high;

pressure is 2.20 per cent. Hence, in order to neutralize all this uncontrollable shrinkage in the gold, that is, 2.20 per cent, some means other than the expansion of the pattern must be used. The expansion of the investment when heated to dry out and burn out the wax is availed of. Minimum gold shrinkage (220 per cent) minus maximum wax expansion (2 per cent) leaves 0.20 per cent shrinkage to be neutralized through the 1nvestment expansion which is 0.85 per cent maximum.

The most rational technique is therefore to utilize the maximum expansion of theinvestment without disintegrating it by maintaining the mold, and hence the contained investment at an elevated temper-. ature' during the drying out and burning out periods, and to supplement this expansion with a correspondingly less than maximum expansion of the wax pattern during the'investing, process, softhat these combined expansions of the pattern wax during investing and the expansion of the investment during drying out and burning out, produce a mold or casting cavity of just I the right size so that'the gold cast therein will on cooling, contract to the same marginal dimensions as the original wax pattern when in the tooth cavity in the month.

By a series of experiments and calculations, taken in connection with this meth 0d of casting, it has been found that the wax pattern should be mantained at an approximate temperature of 115 F. during the investment operation, and that the investment, should .be subjected tea maintained temperature of about 900 F. during the drying out, the burning out and initial part of the casting into temperature.

This method thus takes into consideration the individual contractions and expansions of the pattern, of the investment and of the gold casting during the process of. making the dental inlay, and by controlling the heating etl'ects throughout the entire process, produces a casting of the required marginal dimensions.

Inasmuch as the present invention relates solely to the casting apparatus used in connection with the above process, no further mention of the investment apparatus will ture conditions.

The 'main object of this invention is to provide a mufiie and flask mechanism constructed and arranged to suitably control the temperature of the investment during the drying out, and burning out and castingv operation.

Another object of the present invention is to provide a device of the character described which comprises a flask seat and a suitably heated mutfle, together with means for shifting the mufiie and seat relatively so that the seat supporting the flask With its contained investment can be moved within or without the muffle. I

Still another object of this invention is to provide a device of the character described which includes an electrically heated muffle, a flask seat carriage movable Within the muffle chamber, together with means for controlling the heating effect of said muflle and regulating the temperature thereof at any instant.

Still another object of the invention resides in providing a device in which the flask seat in moving outside of said mullle chamber automatically acts to alter the heating effect of the muifle.

Still another purpose of this invention is to provide an in'iproved muflle for a device of this character in which the inullle is formed with an open chamber around the inner walls of which is arranged a heating coil, the muflie being constructed so that the flask seat in its movement within the muflle will take a position so that the heating wires will entirely surround the same.

A further object of this invention is to provide a muflle of improved construction for use in the above mentioned arrange ment.

A further object of this invention resides in providing a novel arrangement of a mut fie, and flask seat carriage adapted to move the flask seat supported thereby into the mutfle chamber, the flask seat carriage and flask seat being suitably vented to permit the escape of gases and other matter during the drying out and burning out operations.

Still another object of this invention relates to the specific construction of the flask seat itself.

' Another aim of this invention is to provide a novl combination and arrangement of muflle, flask seat and its supporting means, and flask seal mechanism whereby the flask seat supporting means withits flask and contained investment may be shifted from a position within the muflie into contact with the flask seal mechanism.

Yet another object of this invention coniprises the means for automatically locking the flask seat supporting the flask and contained investment in contact with the flask seal.

A further object of this invention resides in providing a flask seat'and flask seal with means for shifting said seat and seal relatively, whereby to contact the flask on'the seat against the seal, together with means for locking the said parts in such position. and means for admitting fluid pressure to the investiment within the flask during the casting operation.

A further object of this invention resides in the means whereby the relative movement between the flask seat and seal control the air pressure admitted to the investment in Another feature of the invention resides in the novel construction of the upper edge of the flask which is adapted to contact against the seal mechanism to maintain an Referring more particularly to the accompanying drawings:

Figure 1 illustrates a perspective view of the entire machine;

Fig. 2 is a fragmentary sectional view illustrating particularly the muffle, the flask seat mechanism, and the flash seal;

Fig. 3 is a sectional detail of the sprue;

Fig. 4 is a bottom view thereof, and

Fig. 5 is a detail sectional View of the flask seat.

Broadly, the invention comprises the supporting standard on which is mounted a muffle provided witl a preferably vertically arranged bore ther hrough, the inner walls of which are formed with heating coils entirely around the same, with electrical con nections to a thermo-electric couple and the usual pyrometer which is also mounted on the base. The heating effect of the muffle is controlled by means of the usual rheostat likewise mounted on the base. Vertically movable through the axis of the muffle bore is arranged the flask seat carriage adapted to support the flask seat, on which is placed the flask with its contained investment, so that when the flask'is lowered into the muflle, it will be entirely surrounded by the heating coil. Arranged in spaced relation to the end in line' with the bore of the muffle is a flask seal mechanism provided with suitable connections to a source of preferably compressed air, and the arrangement of the mufl'le, the flask seat and flask seal is such that the flask seat may be shifted from a point within the mufllc chamber into sealed contacting position, the apparatus being constructed and arranged so that when in this latter position, the flask seat is locked against shifting movement and air pressure is admitted from a tank into contact with the investment within the flask.

Referring more particularly to the accompanying drawings, there is provided the usual base 1 of suitable insulated material, upon which is mounted by means of the standards 2, 3, a suitably formed support 4, to the front end of which is preferably removably attached a muflle 5. As shown. more in detail in Fig. 2, the forward end of the supporting base 4: is provided with a suitable upstanding flange 6 within which is mounted a bushing flange a tubular support 7, which flange, together with the flange 6, forms a support for the mufiie. While the mufl'le may be of any desired shape, and construction, the preferred form comprises an annulus of suitable heat resisting material v8 around the inner periphery of which is continuously wound a heating coil 9, the upper and lower loops of which are suitably embedded in the upper and lower end walls of the annulus 8 by means of any desired fastening means 10. ;The base and top end caps 11 and -12 are provided for covering the exposed ends of the annulus and winding. As shown in the drawings, these caps 11 and12 are suitably cut away as at 13 to clear the winding wires. The upper cap 12 is provided with a central beveled mouth 14 terminating in a projecting lip 15 which forms a suitable opening for the entrance of the flask into the muffle chamber. The base cap ll is likewise cut away and is provided with a central bore 16, the walls of the cap at this point being suitably conformed to provide a supporting surface for the muflie to seat itself upon the upstanding flanges 6 and 7 If desired, an additional'bracket may be provided as at 17 for' attaching the muffle to anupwardly projecting standard 18, which in the present case, is shown as integral with the support 4 on the base. The muflle is providedwith a thermo-electric couple 19 and with suitably insulated connections 20 to the pyrometer 21, illustrated in Fig. 1, which at all times records the temperature of the heating coil. The heating effect in this coil is controlled by the usual rheostat' mounted pref-' erably on the base 1 including the movable arm 22 making contact with a series of re- I sistance contacts 23. The machine is adapted to be connected to an external source of current connected to one contact 22' and to the other contact 23 of the knife switch 24: so that by manually opening and closing thisswitch, current to the machine is out out or in. In addition to this manual control cut off, there is arranged an automatic cut off comprising an arm 25 attached ,to the base of the flask seat carriage here inafter described and adapted to be raised by the elevation of the flask seat carriage to throw the knife switch 2 1 and break the connection.

The investment contained 7 Within the flask is adapted to be heated to the desired temperature by means of the muflle and in order. to introduce the flask within the muflle, there is provided a relative shifting movement between the flask carriage a'nct muffle. The preferred construction for accomplishing this function is shown in the present apparatus, in which the forward part of the base 4 is provided with a vertical bore 24 concentric with the axis of the muflle and the upstanding flanges 6 and 7. Movably mountgtl within this bore is arranged a flask seat carriage, preferably in the formof a plunger 25 provided along its inner lower extremity with the gear teeth 26 (see'Fig. 1), meshing with a pinion 27 mounted on a shaft 28 having bearings 29 and 30 depending from the under side of the base 4. The outer extremity of the shaft 28 is provided with a suitable handle 29 for giving oscillation to the shaft to raise and lower the flask seat carriage.

The flask seat 31 for supporting the flask flask seat 31 which is provided with a tubular shank 33 and a laterally extending annular supporting surface 34 formed with an upstanding flange 35 to form a support-- ing rim fitting snugly within the free end of the flask 32. This upstandingrim is adapted to seat a wafer of porous material for a purpose hereinafter described. This rim 35 is provided with vertical slits 3.5

therearound to permit the escape of thegases from within the flask and likewise the base 34 of the seat is provided with suitably formed vents 36, and for the same purpose, the shank 33 is provided with a central bore opening on to the supporting surface of the base 34. If desired, the hollow shank 33 may be provided with suitable additional vents 37 for a similar purpose sothat when the shank 33 of the flask seat is fitted within the hollow end of the carriage 25, and the flask with its contained investment is seated on the flask seat, with- 1 in the muflle, and the heat generated to burn outthe wax pattern within the investment, the gases, smoke and moisture from the pattern "can escape through the porous insert in the flask seat, throughthe vent slits 35 in the upstanding rim- 35, through the perforations 36 in the base 34, through the bore 38 of the shank 33, and through the vents 37 into the hollow end of the plunger 25, which is also provided with suitable vents 39 for the discharge of these gases, outthrough an opening 40 in front of the support 4. 7

Arrangedabove the muffle 5 and in axial alinement therewith, is a flask seal mecha nism. This mechanism is preferably supported on the standard 18 and comprises a chambered sealing head 42 secured on the standard 18 and overhanging the mufile. Movably mounted Within the chamber 43 on the lower portion of the base 41, is a flask seal comprising a plunger 44 formed with an enlarged annular face 45, peripherally threaded to receive a flange 47 adapted to hold in place a yieldable packing or flask contacting member 48 which is composed of suitable material capable of forming an air tight seal with the upper rim of theflask, which as shown in detail in Fig. 3 is provided with an annular rounded bead 75, which not only insures an air-tight joint at this point, but prevents the packing 48 from being cut by the pressure of the locking mechanism hereinafter described. The plunger 44 is provided with a central bore and projecting nozzle 46 forming an air outlet, The inner end of plunger 44 slides within the chamber 43 in the head 41, and

the inner hole of the head 41. This plug51 is likewise provided with a centrally arranged bore 52 forming an air conduit in axial alinement'with the air conduit 45 and connecting chamber 43 with an upper chamber 53 in the upper portion of the head 41. This chamber 53 is provided with a suitable connection 54 to a source of air or fluid pressure 55. The connection between the ,air conduit 52 and chamber 53 is controlled by an air valve 56 provided with a preferably integral stem 57 sliding in a bore 58 formed in a cap 59 threading into the outer extremity of the head 41. A suitable spring-60 normally seats this valve. Projecting through the threaded plug 51 is an adjustable push rod 61, the upper end of which contacts firmly against the under face of the valve seat, while the lower end of this push rod 61 is provided with an adjustable threaded connection 62 with a similarly threaded inner face of the plunger 44, said connection being suitably; ported as at 63 to permit the passage therethrough of the compressed air. The flask supported on the flask seat in its movement upward, contacts against the flask seal to slightly move the same, thereby admitting compressed air into the flask, and in connection with this construction there is also arranged mechanism for positively and automatically locking the flask seat in this raised seal contacting position. This last named function is accomplished by providing the lower portion of the carriage or plunger 25 with a suitably formed slot- 64 adapted in the raised posi-.

tion of the carriage to come abreast of a locking member 65 slidably mounted within the bore 66 in the support 4. As shown in Fig. 2, this locking member 65 is surrounded by a spring 67 coiled'between an abutment 68 on the locking member and the cap 69 secured to the base so that the spring tends to force the locking member 65 into the slot 64 when in alinement therewith. In order to retract the locking member 65, the same is provided with teeth 70 at its outer end gearing with a pinion 71 on the shaft 72 controlled by an oscillatable lever 73. In order to retain the plunger 25 with its slot in suitable alined position, a key-way 74. is provided on the base of the plunger 25 adjacent the plunger, so that when the plunger is in lowered position'the locking member .65, will project slightly into the key-way 74 to act as a spring pressed retaining means to hold the plunger 25 in any shifted position. The lower face of this key-way is provided with a gradually sloping surface so that the locking member 65 will be forced freely backwardly on the further elevation of the carriage 25. 'lVhen the flask on the flask seat is raised into contact with the flask seal 48, it is thereafter necessary to make this contact air-tight, so that the air pressure thereafter admitted through the seal into the flask will not escape and to accomplish this, it is necessaryto securely lock the flask seat against downward movement prior to the introduction of the air pressure. In order to accomplish this, the upper face of the locking member 65 is provided with a cam surface 65' which, when the look- 'ing member is projected into the slot 64:, acts to give the plunger 25 an additional lifting movement into extreme upper position, at which time, the locking member 65 has passed entirely through slot. 64 under the action of the spring 67. This additional upward movement is permitted by the yielding movement of the plunger 44 of the sealing head. i

The special form of sprue used in con- ,.nection with the improved process set forth in this application is shown in Figures 3 and 4. In this connection, the sprue comprises a base 7 6 provided with an annular flat lateral rim 77 and an inner upstanding flange 78 adapted to fit exactly within the inner periphery of the flask as therein shown, the end of the flask resting on the annular supporting surface 77. The upstanding flange 78 is integral with a central conical projection 79 formed with a 'longitudinal bore 80. The base is likewise provided with a plurality of'spring fingers 81 which project laterally from the plane of the surface 77 to engage the outer periphery of the flask 32 whereby the same is held se-' curely between the spring fingers 81 and the upstanding flange 78, the end of the flask being as before stated, supported permanently on the seat 77 These fingers 81, of which there may be three ormore, are secured to the base member by means of a threaded cap 82 screwing into a suitable recess 83 in the base. Obviously, other modes of forming these fingers and attaching them to the base may suggest themselves. Longitudinally within the central bor 80 of the base is a sprue wire 84: which, as shown in the drawings, is adapted to hold the wax pattern 85 in proper position within the contained investment 86. Means is provided for holding this sprue wire in adusted position, herein shown as a threaded member 87 passing transversely through the threaded cap 82 and engaging the sprue 84:. This adjusting member 87 is provided with a thumb piece 88 to facilitate its turning.

For a complete understanding of the present invention, it is explained that after the ,pattern is formed in the usual manner and placed on the sprue 84, and after the investment material has been A mixed,

are subjected in the investing apparatus to a maintained temperature of approximately one hundred and fifteen degrees F. The pattern is now quickly given the usual preliminary coating and is then placed in the flask to the proper depth by means of the adjustable sprue 84, and the investment introduced around the pattern care being taken to provide a uniform temperature throughout the entire investment process. While it must not be overlooked that when the investment is being poured into the flask and when the pattern is coated, a change in temperature takes place. This change, even though pronounced, is corrected by employing a slow setting investment which does not begin to stiffen under five minutes or more from the time when it is pouredinto the flask, thus allowing ample time for it to regain the loss and impart to the wax the desired determinable temperature, the ultimate desideratum being the temperature of the Wax during the setting of the investment.

Theflask having remained for possibly one-half hour at a constant temperature, the investment hasthen hardened sufficiently to resist any change in the size of the pattern vdue to change in temperature, and so is transferred after removing the sprue and smoothing the crucible in the usual way to the casting apparatus which forms the subject matter of the present invention for the drying out, the burning out, and the'casting operation.

Thefiask with its contained investment having been placed upon the flask seat in the casting machine, and lowered into the electric muflie 5 by rotating the hand lever 29 counter-clockwise, the electric current is then turned on by closing the switch 24,v the rheostat control lever 22 being on the proper contact. By means of the thermoelectric couple which is in the muffle chamber, and connected to the'pyrometer, the degree of heat which is generated in the muifie is recorded on the pyrometer scale, and by means of the rheostat, the temperature of the muflle is under complete control so that the drying out and burning out operations may be completed at the exact temperature demanded. 1

After this operation, the temperature is raised to the desired degree for a suflicient length of time, a given quantity of gold metal is then placed in the ingate and is then very quickly brought to the desired state of liquefaction by the direct application of an oxyhydrogen jet. Prior to this heating the lever 29 is shifted clockwise to lift the flask out of the inufile, and during this upward movement, the finger25' on the base of the plunger 25 has struck the knife switch 24 to break the electric circuit to the heating coil so that thereafter the gold in the ingate is heated solely by the oxyhydrogen jet. At the moment the bead 75 on the top of the flask seat 32 contacts w1th the flask seal 48, the lowest point on the top face of locking key 65 is' in register with the upper edge of the slot 64 in plunger rod 25, hence the compression spring 67 is free to act so that the cam face 65' of the locking member 65 under actuation of the spring forces the flask and flask seal base .48 and flask seat upwardly until the flask seal base plunger 49 meets the fixed packing 50. Just a fraction of a seco d after the seal head starts to move the 1 lve, the push rod 61 contacts with air valve 56 and lifts it off its seat, thus admitting compressed air through the passages 45, 63, chamber 43,

conduit 51, chamber 53, and inlet 54 into the flask and the ingate and forcing the'fluid metal into the-mold in the investment. The force exerted by the cam face 65' of the locking pin actuated by the spring 67 against the top of slot v64, is transmitted through carriage 25, thus automatically establishing an air-tight union between the bead 5 on the flask 32 and the flask seal 48 to securely lock the moving parts in that fixed position.

After the metal casting has crystallized, the flask is released by turning the lever 29 clockwise and the locking pin 65 is withdrawn by means of the oscillation of the handle 73 after-which the flask may easily be lowered to any desired position by turning pinion 27 by means of the handle'29. Furthermore, the front face of the tapered locking pin 65 when not in slot 64 engages with the key-way 74 on the carriage 25, and while the carriage 25 may be easily raised or lowered to anyposition desired other than. that to the position of the flask 'contacting with the sealing'mechanism, it willremain automatically at that particular position for the reason that the end of the locking pin is forced by the spring 67 against the key-way of the carriage.

It is also obvious that many changes in I the details of the .construction and the arrangement of the parts may be made without departing from the spirit of the invention as set forth in the appended claims.

Having thus described the invention, what I claim as new and desire to secure by Letters-Patent, is-- I 1. An electric pneumatic castin machine -com rising a base, an electrical y heated .mu e thereon, a-flask seal mounted on said base adjacent said muflle, means providing a source of air pressure for said seal, a flaskelectric couple and pyrometer mounted on said base and electrically connected to said I ling the muflle heating circuit. 2..An apparatus of the class described comprising a support, an open-top muffle mounted thereon, a flask seat on said sup port adapted to receivea flask and its contained investment, means constructed and arranged to shift said mufile and seat rela tively to position said flask either within or without said muflle while maintaining the investment constantly accessible.

3. An apparatus of the character described comprising a support, a muflle mounted thereon, means for controlling the temperature of said muflle, a flask seat mounted on said support adapted to seat a flask and its contained investment, means for relatively moving said seat and muflle to position the flaskwithin or without the muflle and means for automatically holding said muffle and seat in relatively shifted position. V i

4. An apparatus ,of the character described compr'isinga base, an open-end muf- -fle mounted thereon with the open end uppermost, a flask seat mounted on said base and adapted to support a flask with its contained investment, and means projecting through the lower end of the muffle for raising and lowering said flask into and out of said muflle whereby said invest- -ment is constantly accessible.

5. An apparatus ofthe character described comprising a base, a muffle thereon, means for heating saidmufile, a flask seat mounted on said base, adapted to support a flask with its contained investment, means for moving said flask seat and muflle relatively, and means acting at a certain period in said movement to control the effect of said heating means.

6. An apparatus of the character described comprising a base, a muflle thereon, means for heating said muflle, a flask seat on said base adapted to support a flask with its contained investment, means for moving said seat within and without said muflle, said means acting to control said heating effect when said flask seat is moved away from said muflle.

7. An apparatus of the class described comprising atubular support, an openended muflle mounted thereon, a flask carriage shiftable through said tubular support, a flask seat on said carriage for supporting an investment, and means for shiftmg said carriage to position said flask seat within and without said muflle.

8. An apparatus of the class described,

comprising a support, a muflie mounted thereon, a flask carriage shiftable on said support, a flask seat on said carriage, means forshifting said carriage, and a spring pressed detent normally engaging said carriage to hold the same in shifted position.

9. A device of the character described comprising a tubular support, an openendcd muflle mounted thereon, a tubular flask seat carriage slidably mounted within said support and movable axially through said muffle, and a tubular flask seat detachably nesting in said tubular carriage, said seat, carriage and support being suitably vented to permit the escape of moisture, gases and smoke therethrough.

10. A device of the class described comprising a support, an open-ended muflle mounted thereon, a flask seat carriage disposed axially of and shiftable through said support, a flask seat detachably connected to the upper end of said carriage and adapted to support a flask with its contained investment, and means for raising and lowering the flask seat into and out ofthe muflle.

11. A device of the class described comprising a ventilated support, an open-ended muflle mounted thereon, a flask seat carriage disposed axially through said support, a vented flask seat disposed in the upper end of said carriage, said carriage having a suitable number of vents communicating with the vents of said seat, and means for raising and lowering said seat with respect to said 12. A flask seatfor a device of the character described comprising a hollow vented shank having a laterally disposed disk-like support, said disk having an annular upstanding flan'ge adapted to engage the walls of said flask, the bore of said shank connecting with the faces of said disk, said disk and flange also having a suitable number of vents.-

13. A flask seat comprising a tubular shank vented and formed at its upper portion with a lateral disk having an annular upstanding flange adapted to form a seat for the flask, said flange and the upper face of said disk being suitably vented, the upper face of said disk communicating'with the bore of said shank and a substantially thin disk of porous material superimposed on the upper face of said disk and lying within said flange.

14. A device of the character described comprising a support, an open-ended mufiie mounted thereon, a flask seat carriage mounted on said base below said muflie and movable axially therethrough, a flask seal supported by said base and arranged above and axially of said muflle, and means for shifting said flask seat from a position within said muffle to flask seal contacting position.

15. A device of the class described comprising a base, an open-ended mufiie supported thereon, a flask seat carriage and a flask sea] supported by said base and located axially of said nuiflie below and above said muflle, respectively, means for moving said carriage into contact with said seal.

16. =An apparatus of the character described coin 'irising a base, a flask seat and a flask seal supported thereon, means for shifting said seal and seat relatively whereby the flask on said seat and the seal contact, automatic means for locking said parts in such position.

17. An apparatus of the character described comprising a base, a flask seat and a flask seal supported thereon, means for shifting said seat into yielding contact with said seal, means for giving said seat and seal an additional shifting movement whereby said flask is locked in seal engaging position, and means controlled by the yielding of said seal for altering the air pressure in said sealed flask. i

18. An apparatus of the character described com-prising a base, a flask seat and a flask seal supported thereon, means for shifting said seat with its supported flask into contact with said seal, means for giving said seat an additional shifting movement wherebysaid flask is locked in seal engaging position, said additional movement acting to admit fluid pressure into said flask for the purpose set forth.

v 19. An' apparatus of the character described comprising a-base, a flask seat movably mounted thereon, a flask seal yieldably mounted thereon and constructed and arranged to be moved by said flask seat moving means into a non-yielding position, and means brought into operation by said yielding movement of said seal for locking said seat against further movement.

20. An apparatus of the character de-.

scribed comprising a base, a flask seal mounted thereon, a flask sea-t formed with a slot carriage, means for moving saidcarriage toward said seal, and a spring actuated locking member operable to enter said scribed comprising a base, a flask seat mov-- ably mounted thereon, a flask seal yieldably mounted against a rigid abutment on said base, said seal having a fluid pressure inlet,

a valve therefor, and means for moving said seat with the flask supported thereon into contact with said seal whereby said seal is shifted and said valve is opened to admit fluid pressure to said flask.

23.1An apparatus of the class described comprising a support, a muflle mounted thereon, a flask carriage shii'table on said support, a flask seat on said carriage, means for shifting said carriage, a spring pressed detent normally projected into the path of said carriage, said carriage having a slot therethrough to receive said detent whereby to lock said carriage in desired position.

24. A device of the class described comprising a base, an open-ended mufile sup- -ported thereon, a flask seal supported on said base in spaced relation to one open side of said muflie, a flask seat carriage supported on said lease and movable from a heating position Within said muiile to a flask contacting position outside of said mufiie.

25. A device ofthe class described comprising a/support, an open-ended muflle thereon, a flask seal on said support and spaced from the open end of said muffle,

and a flask carriageshiftable on said support from a position between said muffle and seal into heating and sealing positions, respectively.

26'. An apparatus of the character described comprising a base, a yieldable flask seal thereon, means controlled by the yielding of said'seal for altering the working pressurein said seal, a shiftable flask carriage provided with a locking slot, means for moving said carriage to shift said flask into contact with said seal, a spring pressed tent being constructed and arranged to give said carriage an extra movement toward said flask seal to operate the pressure controlling mechanism.

27. In a device of the character described, a support, a shiitable liask seal thereon, fluid pressure controlling means operated by the shifting of said seal, a movable carriage having a groove and a slot therein, a flask seat thereon, means for moving said carriage, a spring pressed detent normally projected into said groove and adapted to enter said slot on movement of said carriage, and means for retracting said detent- 28. In a device of the character described,

a support, a shiitable flask seat thereon, a

shiftable seal thereon provided with an air passage, a spring pressed valve in said passage normally closing the same, a source of air pressure connected to said passage, said valve and seal being constructed and-arranged so that on movement of said seal said valve will shift to open said passage.

29. In a device of the character described, the combination of a support including an overhanging arm, an open-ended muflle on said support. a seal on said arm overhanging said muflle, a flask seat carriage carried by said support and shifta'ble axially through said muffle into contact With said seal. and means on said support for shifting said carriage. In testimony whereof, I aflix my signa- -ture.

CHRIS s. VAN onu.

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