Fluid-tight coupling device for a feeder pipe

Information

  • Patent Grant
  • 6216766
  • Patent Number
    6,216,766
  • Date Filed
    Monday, November 13, 1995
    29 years ago
  • Date Issued
    Tuesday, April 17, 2001
    23 years ago
Abstract
A pipe conveying molten material upwards from a pressurized receptacle into the mold of a low pressure diecasting machine, positioned on and supported by the receptacle, is secured in a fluid-tight fit by an adjustable coupling device. One end of the pipe extends through the topmost wall of the receptacle to pick up the molten material and the other terminates in a head located externally of the receptacle and tightened together with a seal against the mold. The outer surface of the pipe head has at least one substantially frusto conical portion matched to the surfaces of a plurality of wedges disposed circumferentially around the pipe and mounted on slide ways which can be directed by suitable actuators from an at-rest position to an operating position in which the pipe is subjected to an axial force with the pipe head clamped together with the seal against the machine.
Description




BACKGROUND OF THE INVENTION




The present invention relates to a device to effect a fluid-tight coupling around a pipe serving to convey molten material, as part of the connection between a low pressure diecasting machine and a pressurizable receptacle in which the molten material is prepared. The device disclosed is well suited for application to a pipe fashioned from fragile material, insertable typically through one wall of the receptacle, which comprises a body having an inlet end that is located internally of the receptacle and a head at the pipe outlet end whose surface can be coupled in fluid-tight association with a mold coupled to the low pressure diecasting machine.




A low pressure diecasting machine of the type in question is mounted on and connected to a receptacle containing molten material in a manner such that the pipe is aligned and connected with the injection nozzles of a mold connected to the machine.




The prior art systems employed in making such a connection, while based on a variety of techniques, are similar inasmuch as all permit removing the machine from the receptacle. In effect, the machine rests on the receptacle during operation and can be moved to a non-operating position whenever the need arises to gain access to the inside of the receptacle. To ensure the features of a removable connection that can be successfully operated, the pressure-tight fit between the nozzles and the front end surface of the head of the pipe is obtained by interposing seals of gaskets of suitable thickness. The efficiency of the sealing action in containing the pressure of the molten material is somewhat critical, given that the tightness of the fit between the front end surface of the pipe and the nozzle of the mold relies only on a suitably strong force of compression.




In practice, this is achieved by packing the space between the machine and the head of the pipe to an overall depth nominally greater than that of the existing gap, so that the fluid-tight barrier will be established by a compressive force provided by the total weight of the low pressure diecasting machine.




Quite apart from the operational inconvenience and the empirical nature of such a system, selection of the optimum condition depends on a process of trial and error. The working principle underlying this method of connection tends to result in a high degree of structural stress on the pipe. In other solutions, the receptacle is forced vertically into association with the diecasting machine through the agency of suitable lifting means, the force in this instance being applied laterally.




Owing to the intense and uncontrollable impact of these stresses, rupture of the pipe frequently occurs, particularly when the pipe, as already intimated, is made of a fragile material, such as silicon nitride or other ceramics typically utilized in the context of low pressure diecasting processes for aluminum alloys.




Conversely, the application of a smaller compressive force to the sealing medium might well diminish the risk of pipe rupture, but would not ensure an efficient sealing action to accommodate the pressure of the fluid flowing at high temperature through the pipe. In short, a solution that succeeds both in avoiding the risk of rupture to the pipe and in ensuring an efficient seal must necessarily involve a compromise between the two opposing requirements outlined above.




OBJECT OF THE INVENTION




Accordingly, the object of the present invention is to overcome the aforementioned drawbacks, providing a solution to the problem of ensuring an efficient sealing action between pipe and mold by adopting a novel arrangement for compressing the interposed sealing medium, and allowing for adjustment of the force by which the sealing action is assured.




SUMMARY OF THE INVENTION




The stated object is realized by a device in which a pipe for conveying molten material can be coupled adjustably and in a pressure-tight fit as part of the connection between a low pressure diecasting machine and a pressurizable receptacle for preparation of the molten material.




The pipe passes through one wall of the receptacle and has a body affording a head coinciding with an outlet end whose front surface can be coupled to the mold of the low pressure diecasting machine together with an interposed sealing medium. The design of the device takes account of the fact that the outer surface of the pipe as supplied by the manufacturer has at least one portion which is angled in relation to the axis of the pipe itself. In a preferred embodiment described below, the outer surface of the pipe comprises a portion of the head that has a substantially frustoconical shape.




The device itself comprises three wedges disposed circumferentially around the pipe between the head and the wall of the receptacle. Each wedge has a surface matched to the aforementioned angled portion of the pipe in such a manner that the surfaces can be coupled together. In addition, the three wedges are mounted slidably on corresponding ways and are thus capable of movement in relation to the wall of the receptacle, transversely to the axis of the pipe through the agency of an actuator means. The movement is brought about between a non-operating at-rest position of the wedges spaced from the pipe, and an operating position of close proximity of the wedges to the pipe in which the wedges apply an axial force such as will tend to draw the pipe outward from the receptacle and, in consequence, cause the head to be clamped together with the sealing medium against the mold of the low pressure diecasting machine. The three wedges are thus able to generate the requisite sealing action, at least across the front end surface of the head, in opposition to the pressure of the molten material flowing along the pipe.




The principal advantage of a device according to the invention is that the optimum clamping force for a given pipe can be determined by a continuous incremental type of adjustment in which the weight of the machine plays no part whatever.











BRIEF DESCRIPTION OF THE DRAWINGS




The invention will now be described in detail, by way of example, with the aid of the accompanying drawings, in which:





FIG. 1

is an overall sectional view illustrating a device according to the invention, shown fitted to a low pressure diecasting machine associated with a receptacle containing molten material, in which the pipe is shown in a first embodiment;





FIG. 2

shows the device according to the invention in a further section, enlarged in relation to FIG.


1


and taken through lines II—II of

FIG. 3

;





FIG. 3

illustrates the device of

FIG. 2

viewed in plan from above;




FIG.


4


and

FIG. 5

illustrate a first detail of the device viewed respectively in plan and in a section through V—V of

FIG. 4

;




FIG.


6


and

FIG. 7

illustrate a second detail of the device viewed respectively in plan and in a section through lines VII—VII of

FIG. 6

;




FIG.


8


and

FIG. 9

illustrate a third detail of the device viewed respectively in plan and in a section through lines IX—IX of

FIG. 8

;




FIG.


10


and

FIG. 11

show a detail of the device in an alternative embodiment, illustrated respectively in a partial sectional view and in plan; and





FIGS. 12

,


13


,


14


and


15


illustrate four alternative embodiments of the pipe.











DESCRIPTION OF THE PREFERRED EMBODIMENTS




With reference to the accompanying drawings, and to

FIGS. 1 and 2

in particular, the present invention relates substantially to an adjustable coupling device


9


by means of which a feeder pipe


1


conveying molten material is connected in a pressure-tight fit to a low pressure diecasting machine


2


associated with a pressurizable receptacle


3


in which the molten material is prepared.




The low pressure diecasting machine


2


is supported during operation by the receptacle


3


, of which the top horizontal wall


4


has thereon a set of stands


30


for this purpose. When not in operation, the machine


2


can be removed from the receptacle


3


(see phantom lines in

FIG. 1

) by a combination of lateral translation and elevation on angled ways, not illustrated in the drawings, in such a way as to afford internal access to the receptacle


3


.




The pipe


1


is typically of fragile ceramic material, preferably silicon nitride, and passes through the top horizontal wall


4


of the receptacle


3


. Seen in its entirety, the pipe has a body


5


with an inlet end


27


which extends into a crucible


33


positioned within the receptacle


3


. The pipe also has a head


6


at an opposite outlet end


7


of which the front surface


8


is designed to locate against a mold


17


fitted to the low pressure diecasting machine


2


with an interposed seal


28


as will be described.




A preferred embodiment of the device


9


(shown in

FIG. 2

) is designed for use in conjunction with a pipe


1


of which the outer surface


10


has an annular portion


13


of frustoconical shape located at the head end


6


, which preferably has an angle of 30° relative to the longitudinal axis


11


of the pipe


1


. It will, of course, be sufficient in practice that the annular portion


13


of the outer surface


10


has a different type of taper in relation to the axis


11


of the pipe


1


, as indicated in

FIGS. 12

,


13


and


14


. To this end, the pipe


1


shown in

FIG. 12

has a separately embodied flange


34


whose outer surface


10


affords the frustoconical annular portion


13


. The pipe


1


of

FIG. 13

has an enlarged collar with a plain shoulder, the frustoconical portion


13


in this instance provided by a thrust ring


35


. In the example of

FIG. 14

, the entire head


6


of the pipe


1


has a splayed flange


36


of “V” shaped profile which creates the frustoconical portion


13


.




Referring in particular to

FIGS. 2

,


4


and


5


, the device


9


has three identical wedges


12


to be disposed around the head


6


of the pipe


1


at equal angular intervals of 120° and designed to operate between the head


6


of the pipe


1


and the wall


4


of the receptacle


3


.




Each wedge


12


has a surface


15


matched to the frustoconical portion


13


of the outer surface


10


of the pipe


1


in such a manner that the three wedges can be coupled circumferentially with the pipe portion


13


.




In addition, the wedges


12


are mounted slidably to respective slide ways


2


(see

FIGS. 6 and 7

) formed partly within the wedges themselves and partly, as indicated by the number


20




a


, within a flange


19


by which the entire device


9


is secured to the wall


4


of the receptacle


3


. This makes each of the wedges capable of movement in relation to the wall


4


transversely to the axis


11


of the pipe


1


through the agency of a corresponding actuator means


16


.




In an alternative embodiment, illustrated in

FIG. 15

, the head


6


of the pipe


1


has a downwardly directed surface


37


disposed obliquely in relation to the pipe longitudinal axis


11


and performs the same function as the aforementioned frustoconical annular portion


13


. More specifically, the downwardly directed surface


37


affords an inclined plane that can be coupled with a wedge


12


mounted in such a way as to operate and interact adjustably with the head


6


essentially in the same manner as described above for other embodiments.




In particular, it is seen from

FIG. 2

that the flange


19


is secured to the wall


4


of the receptacle


3


by means of screws


32


with a gasket


38


interposed. In addition, the part


20




a


of the slide way formed in the flange


19


affords a fixed key


31


insertable into the slide way


20


of the wedge


12


serving to guide the sliding movement of the wedge. The device


9


further comprises an annular plate


18


providing a structural interface between the low pressure diecasting machine


2


and the receptacle


3


. The plate


18


is positioned coaxially in relation to the pipe


1


, between the machine


2


and the head


6


, and has a bush


22


of ceramic material disposed in axial alignment with the pipe through which the molten material flows during the injection stage.




As indicated in

FIGS. 2 and 3

, the annular plate


18


is secured to the flange


19


with bolts


29


and has a peripheral rim


24


shaped in such a way as to transmit the structural loads deriving from the force of mass exchanged between the low pressure diecasting machine


2


and the pressurized receptacle


3


on which the machine is supported. In addition, the peripheral rim


24


encompasses the head


6


and the wedges


12


, so that there is no structural interaction between these components and the plate


18


.




Nonetheless, the peripheral rim


24


of the plate


18


can be coupled with the wedges


12


. As seen from

FIG. 2

, in effect, the rim


24


and the wedges


12


have respective matching frustoconical surfaces


25


and


26


positioned so as to engage one with another when the plate


18


is secured to the receptacle


3


, with the result that the wedges


12


are clamped against the head


6


by a force applied at right angles to the axis


11


of the pipe


1


. Thus, whenever the annular plate


18


is bolted onto the flange


19


, the frustoconical surface


25


of rim


24


is caused to slide against the matching surfaces


26


of the wedges


12


, forcing the wedges in their turn to slide along the respective ways


20


and move from an at-rest position distanced from the pipe


1


toward an operating position of close proximity to the pipe


1


. In this close-coupled position, and indeed during any further movement in the same direction, the inner surfaces


15


of the wedges will engage on the matching frustoconical portion


13


of the outer surface


10


of the head


6


producing an axial force that tends to lift the pipe


1


from the receptacle


3


. The orientation of the taper on the surfaces denoted


25


and


26


is opposite to that of the frustoconical annular portion


13


afforded by the outer surface


10


of the pipe


1


, and the angle of inclination also different, for example 20° in the embodiment illustrated. Thus, it is the angled surface


25


of the peripheral rim


24


of the annular plate


18


provides the aforementioned actuator means


16


to drive the wedges


12


.




As regards the operation of the device


9


, it is seen from

FIG. 2

that the action of the flange


18


on the wedges


12


can be optimized by the adoption of actuator means


16


in a wide variety of different yet substantially equivalent solutions; for example, by including setscrews


21


insertable through the peripheral rim


24


of the plate


18


and engaging each of the wedges


12


. The wedges can be moved further along the respective slide ways


29


and thereby obtain a fine adjustment of the clamping action applied to the pipe


1


.




As a result of the axial force generated through the clamping action, the front end surface


8


of the head


6


of the pipe


1


is driven against and ultimately impeded by the plate


18


. Accordingly, the seal


28


can be pinched securely between the head


6


and the plate


18


creating a pressure-tight barrier to the molten material flowing through the pipe


1


. Clearly, any leakage of the molten material between the head


6


and the surrounding wedges


12


will be prevented by locating similar seals


28


at least against the frustoconical annular portion


13


extending between the head


6


and the body


5


of the pipe


1


.




A device


9


as shown ensures the fluid-tight fit needed to prevent any egress of the molten material from the pipe


1


and of setting the clamping force at the exact values required to produce an efficient seal. This is accomplished without inducing overloads liable to present an excessive risk to the integrity of the pipe


1


. Moreover, not only does the weight of the low pressure diecasting machine


2


have no bearing whatever on the clamping force, but the force is applied statically and at a velocity that can be selected and controlled at will. This is in contrast to prior art type solutions where the inevitably high load generated by the weight of the machine


2


is applied instantaneously, hence in the manner of a dynamic load and with particularly adverse consequences for fragile materials.





FIGS. 10 and 11

illustrate an alternative embodiment of the device


9


wherein the plate


18


is eliminated and the flange


19


has peripheral projections


39


on which the low pressure diecasting machine


2


rests directly, supported thus by the receptacle


3


. The wedges


12


in this instance are clamped against the head


6


of the pipe


1


, and the relative surfaces


15


coupled consequently with the frustoconical portion


13


of the outer surface


10


, by actuator means


40


comprising a screw


21


operating between the peripheral projection


39


and the wedge


12


.




Finally, other possible variations in embodiment of the actuator means


16


include the adoption of fluid power actuators


23


associated with the wedges


12


in place of the screws


21


(see FIG.


9


).



Claims
  • 1. A low pressure die casting apparatus including a fluid-tight coupling device for a pipe conveying molten material for the connection of a low pressure diecasting machine to a receptacle containing the molten material, wherein the pipe passes through one wall of the receptacle and has an inlet end extending internally of the receptacle so as to admit the molten material and also a head located externally of the receptacle and having a front end surface to be associated by way of an interposed seal with a mold fitted to the machine, the outer surface of the pipe head having at least one portion which is angled in relation to the pipe longitudinal axis, the device comprising at least one wedge for operating between the pipe head and the wall of the receptacle and having a surface matched to the angled portion of the pipe head outer surface so as to interact adjustably therewith, said at least one wedge being mounted in a side way and capable of movement with respect to the wall of the receptacle transversely to the pipe longitudinal axis by an actuator means between a non-operating position spaced from the pipe and an operating position of close proximity to the pipe in which the surface of the wedge is coupled to the pipe head at least one angled portion, applying an axial force by which the pipe is caused to move away from the receptacle and the head tightened against the low pressure diecasting machine and against the interposed seal, producing a tight fit at least across the head front end surface to contain the pressure of the molten material flowing through the pipe.
  • 2. A device as in claim 1, comprising an annular plate providing a structural interface between the low pressure diecasting machine and the receptacle disposed coaxial with the pipe and positioned between the low pressure diecasting machine and the pipe so as to engage the head and thus oppose the axial action generated through the pipe by the movement of the said at least one wedge toward the operating position.
  • 3. A device as in claim 2, wherein the annular plate has a peripheral rim and proportioned to encompass the pipe head and the wedge.
  • 4. A device as in claim 3, wherein the peripheral rim of the annular plate has an angled inner surface matched to a correspondingly angled outer surface of the at least one wedge, so that when the plate is secured to the receptacle, said plate angled inner surface and said wedge outer surface will be coupled mutually to allow clamping of the wedge against the head of the pipe in a direction transverse to the pipe axis, the angled inner surface of the plate acting as the actuator means by which the wedge is operated.
  • 5. A device as in claim 4, wherein the two mutually coupled surfaces of the plate and wedge are angled oppositely to the surface of the wedge for engaging the at least one angled portion of the pipe head outer surface.
  • 6. A device as in claim 1, comprising three independent wedges disposed circumferentially and peripherally around the pipe head.
  • 7. A device as in claim 6, wherein the wedges are identical and distributed around the pipe head at equal angular distances.
  • 8. A device as in claim 1, further comprising an annular plate providing a structural interface between the low pressure diecasting machine and the receptacle, and a flange interposed between the plate and the wall of the receptacle to secure the plate to the wall, wherein the flange has thereon one part of at least one slide way accommodating the movement of a wedge.
  • 9. A device as in claim 1, wherein actuator means comprises at least one screw to engage and move the wedge along the slide way.
  • 10. A device as in claim 1, wherein the actuator means comprises a fluid power actuator to move the wedge along the slide way.
  • 11. A device as in claim 8, further comprising a flange presenting at least one peripheral projection on which the low pressure diecasting machine rests to be supported by the receptacle, and actuator means to operate between the peripheral projection and the at least one wedge to clamp the wedge against the head of the pipe, the surface of the wedge being coupled with the angled portion of the pipe head outer surface.
  • 12. A device as in claim 2, wherein the annular plate further comprises a ceramic bush in coaxial alignment with the pipe.
Priority Claims (1)
Number Date Country Kind
B094A0531 Nov 1994 IT
US Referenced Citations (2)
Number Name Date Kind
3163897 Sylvester Jan 1965
4995535 Ooya et al. Feb 1991
Foreign Referenced Citations (7)
Number Date Country
C-1 156 942 May 1964 DE
A-53 279 May 1967 DE
B-1 508 753 Apr 1969 DE
A-0 379 420 Jul 1990 EP
573053 Feb 1958 IT
573054 Feb 1958 IT
6-114529 Apr 1994 JP
Non-Patent Literature Citations (1)
Entry
Patent Abstracts of Japan vol. 17 No. 103 (M-1374), Mar. 2, 1993 & JP-A-04 294854 (Toyota Motor) Oct. 19, 1992 *abstract*.