MXPA97001872A - Volume discharge handle consta - Google Patents

Abstract

The present invention relates to a discharge melting sleeve having a spill orifice and a spill valve for selectively opening and closing the spill orifice. The spill orifice extends through the discharge sleeve at a level below the pouring orifice to allow molten material in excess of a predetermined volume to spill from the discharge sleeve. When opened, the spill hole allows excess metal to spill from the discharge sleeve. When closed, the metal can be expelled from the sleeve without spilling additional material through the spill hole.

Description

CONSTANT VOLUME DISCHARGE SLEEVE BACKGROUND OF THE INVENTION The present invention relates to a die casting equipment, and more particularly to a metal supply discharge sleeve, through which the molten metal is transferred to a die. Die casting is a technology commonly used to make a wide range of metal articles. Typically, two or more parts of the matrix are provided, each defining a space corresponding in shape to a portion of the article to be melted. When the parts of the matrix are brought together, these spaces cooperate to define a cavity of the matrix in the form of an article to be cast or cast. The molten metal is introduced into the cavity of the matrix and allowed to cure - typically by cooling. Once the article is sufficiently cured, the parts of the matrix open and the emptied article is removed. The parts of the matrix can be closed again and the process repeated to empty the desired number of identical items. A conventional die casting apparatus is illustrated in Figure 1 and generally designated 100. The REF: 24193 die casting apparatus 100 includes a die assembly 108, which receives the molten material from a discharge sleeve assembly 110. The die assembly 108 includes a pair of die halves 102 and 104 each formed with a space. When the two halves of the matrix 102 and 104 are brought together, their respective spaces co-operate to form a die cavity 106 corresponding to the shape of the article to be cast. The molten metal is introduced into the cavity of the die 106 by means of the assembly of the discharge sleeve 110, which includes a discharge sleeve 112 defining an internal orifice 114. The discharge sleeve 112 extends in the assembly of the matrix 108, such that the inner hole 114 is in fluid communication with the cavity of the die 106. The discharge sleeve 112 includes a pouring orifice 116 for introducing the molten material into the discharge sleeve. A piston 118 reciprocates within the discharge sleeve 112 to eject the molten metal from the inner bore 114 within the die cavity 106. The piston 118 is connected to a hydraulic cylinder 120 by a drive rod 122. The extension of the piston 118 injects the molten metal into the sleeve 112 into the die cavity 106. The retraction of the piston 118 pulls the piston 118 to allow the sleeve 112 to be refilled through the pouring orifice 116 for the next discharge. With recent advances in pressure casting techniques and processes, it is important to ensure that a precise volume of metal is introduced into the discharge sleeve for injection into the matrix. The provision of accurate volumes of metal allows the system designer to design and consistently replicate the proper position and character of the metal during the pressure cast operation. The long-accepted technique of simply casting the metal in the discharge sleeve through a pouring orifice does not provide the precision required in many applications today. Accordingly, the inventor of the present application has developed various techniques and approaches for filling a die casting sleeve with a precise volume of metal, by coupling the internal volume of the discharge sleeve with the desired volume of material. For example, U.S. Patent No. 5,205,338 issued April 27, 1993 to Shimmell, discloses a system having a filling cylinder that intersects the discharge sleeve and includes an alternating slide valve to seal the discharge sleeve. . After the discharge sleeve is filled with material and before the piston is advanced, the slide valve is actuated to seal the pouring orifice in the discharge sleeve. The closed discharge sleeve provides a constant volume discharge, which corresponds to the internal volume of the discharge sleeve. Another example, U.S. Application Serial No. 08 / 280,159 filed July 25, 1994 by Shimmell, discloses a discharge sleeve with a rotatable driven collar around the pouring orifice. In a first position, the collar allows the sleeve to be filled. In a second position, the collar completely closes the filled sleeve in preparation for driving the piston. Again, the sleeve provides a constant volume discharge corresponding to the internal volume of the discharge sleeve. Yet another example, U.S. Patent Application Serial No. 08 / 468,256 filed June 6, 1995 by Shimmell, discloses a discharge sleeve that is inclined downwardly from the pouring orifice. The molten metal is cast into the discharge sleeve until it fills the discharge sleeve until the pouring orifice leaves only a small amount of air inside the discharge sleeve. As the piston advances, the air in the sleeve is expelled through the pouring orifice. Due to the shape and arrangement of the pouring orifice, the air completely expelled from the sleeve, as much as the pouring orifice is sealed by the piston. The inclined discharge sleeve provides a constant volume discharge, which corresponds to the internal volume of the forward discharge sleeve of the pouring orifice. Although all these constructions are reliable and effective, they require that the discharge sleeve be completely filled with molten metal at each discharge.

BRIEF DESCRIPTION OF THE INVENTION The problems mentioned in the above are overcome by the present invention, in which a discharge sleeve includes a spill hole and the spill valve for controlling the volume of molten material within the sleeve. The spill hole extends through the wall of the discharge sleeve, allowing the molten material to spill out of the discharge sleeve, once it has reached a specific level corresponding to a specific volume. The spill valve alternates within the spill hole to selectively open and seal the orifice.

During the operation, the spill valve is closed to seal the spill hole, before the molten material is introduced into the discharge sleeve. The molten material is cast into the sleeve through the pouring orifice until the level of the material is above the spill hole. The spill valve then opens to allow excess material to spill out of the sleeve through the spill hole. Then the valve is closed to seal the leak hole and the piston is advanced to inject the molten material into the die cavity. The present invention provides a simple and effective discharge sleeve system, which is capable of providing a fixed volume discharge, without the need to completely fill the discharge sleeve prior to injection. In addition, the present invention can operate as a conventional discharge sleeve, simply by keeping the spill valve in the closed position. These and other objects, advantages and features of the invention will be more readily understood and will be appreciated by reference to the detailed description of the preferred embodiment and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a side elevation, sectional view of a die casting apparatus according to the prior art; Figure 2 is a perspective view of a portion of the discharge sleeve system of the present invention; Figure 3 is a sectional view of the discharge sleeve showing the leak orifice in the open position; Figure 4 is a sectional view of the discharge sleeve showing the leak orifice in the closed position; and Figure 5 is a sectional view of an alternative discharge sleeve with an alternative spill hole in the open position.

DETAILED DESCRIPTION OF THE PREFERRED MODALITY A discharge sleeve system according to a preferred embodiment of the present invention is illustrated in Figure 2 and designated generally 10. The discharge sleeve system 10 is adapted for use with a conventional pressure casting apparatus. Figure 1 shows a prior art die casting apparatus 100, having a conventional die assembly 108 and a conventional discharge sleeve system 110. The die assembly 108 defines a die cavity 106 in the shape of the article to be emptied. The discharge sleeve system 110 injects molten material into the die cavity 106 to create the molten article. The discharge sleeve system 10 of the present invention is intended to replace the conventional discharge sleeve system 110 shown in Figure 1. The discharge sleeve system 10 of the present invention is integrated into the casting apparatus of the present invention. pressure 100 by interconnecting the discharge sleeve system 10 and the matrix assembly 108 in the conventional manner shown in Figure 1. The molten material is cast into the discharge sleeve system 10 and then forced into the matrix by an arrangement of conventional piston, to create cast or cast items. Although the present invention is described in connection with a conventional die casting apparatus, it is also well suited for use with other types of injection molding systems, including polymeric injection molding systems. The discharge sleeve system 10 includes a discharge sleeve 12 which is generally cylindrical and includes a circumferential wall 22 defining a concentric internal orifice 20. The discharge sleeve 12 includes a die end (not shown) that is adapted to penetrate the array assembly in the same manner as the conventional discharge sleeve 112 shown in Figure 1, thereby allowing fluid communication between the internal hole 20 and the die cavity. The discharge sleeve also includes a piston end 26 that is open to receive the piston 14 as shown in Figure 2. The discharge sleeve 12 defines a generally circular pouring orifice 18, near the end of the piston 26. The orifice casting 18 is in communication with internal bore 20, allowing the molten metal to be cast into internal bore 20. Discharge sleeve 12 also defines a bore hole 28 to allow molten metal in excess of a predetermined volume, spill from the inner bore 20. The bore hole 28 is generally circular and extends completely through the circumferential wall 22 along a substantially horizontal axis. The spill hole 28 is positioned proximate the end of the piston 26 of the discharge sleeve 12, such that it does not carry the elevated internal pressure generated within the discharge sleeve 12 as the piston 14 is advanced. The diameter of the spill hole 28 will vary from application to application to control the volume of the discharge sleeve 12. The discharge sleeve system 10 also includes a spill valve 30 positioned within the spill hole 28. The spill valve 30 alternating to selectively open and close the spill hole 28. The spill valve 30 is connected to a conventional drive mechanism (not shown) such as a hydraulic or pneumatic cylinder. The spill valve 30 is generally cylindrical and includes inner and outer ends 34 and 36, respectively. The outer diameter of the spill valve is slightly smaller than the inner diameter of the spill hole 28. Narrow tolerances between the orifice 28 and the valve 30 prevent the molten metal under pressure from leaking out of the sleeve around the closed valve. A slot 32 is defined along the lower center of the spill valve 30. The slot 32 is defined by the top wall 40 and the opposite side walls 42 and 44. The slot 32 provides a flow path 38 for the metal molten spill from the sleeve 12 when the valve is in the open position (See Figure 3). The opposite side walls 42 and 44 are obtuse with respect to the top wall 40 to increase the cross-sectional area of the opposite ends of the flow path 38. Additionally, the inner end 36 of the valve 30 is concave to engage the contour of the inner surface of the circumferential wall 22, when the valve is in the closed position (See Figure 4). This allows the piston 14 to alternate without interference from the valve 30. Although the currently preferred spill orifice 28 and the spill valve 30 are circular in cross section, they may vary in cross section, as desired. As mentioned in the above, the discharge sleeve system 10 includes a conventional piston arrangement 50, for forcing the molten metal from the discharge sleeve 12 into the die cavity (not shown). The piston arrangement 50 includes a piston 14 seated within the inner bore 20, a driving rod 16 connected to the piston 14 and a hydraulic cylinder (not shown) for alternating the driving rod 16 and consequently the piston 14, within the inner bore. 20. The driving rod 16 extends from the hydraulic cylinder (not shown) to the piston 14 through the end 26 of the piston of the discharge sleeve 12. When the hydraulic cylinder is extended, the driving rod 16 pushes the piston 14 forward into the inner hole 20 of the discharge sleeve 12, forcing the molten material out of the discharge sleeve 12 into the die cavity. When the hydraulic cylinder is retracted, the driving rod 16 pulls the piston 14 back towards the end 26 of the piston of the discharge sleeve 12.

Operation Initially, the die assembly is prepared for casting in a conventional manner. Generally, the halves of the matrix are closed to define a matrix cavity in the form of a desired, emptied article. Further, the piston 14 is fully retracted by the operation of the hydraulic cylinder (not shown), and the spill valve 30 is closed by the operation of a conventional drive mechanism (not shown). The spill valve 30 is closed by the placement within the spill hole, so as to fill the spill hole 28 by eliminating the flow path 38. At this point, the discharge sleeve 12 is ready to receive the molten metal. The molten metal M is cast into the discharge sleeve 12 through the pouring hole 18 until the internal orifice 20 is filled above the height of the spill hole 28. Once the discharge sleeve 12 is sufficiently filled, a slight rest period is provided to allow the molten metal M to level out. Then, the spill valve 30 is opened by moving it within the discharge sleeve 12 until the slot 32 forms the bridge of the circumferential wall 22 to define the flow path 38 (See Figure 3). This allows the molten metal to spill from the sleeve 12 through the flow path 38, until the level of metal in the sleeve 12 reaches the bottom of the spill hole 28. A receptacle (not shown) can be placed for trap the molten metal that spills out of the spill hole 28 for reuse. After the excess metal has been spilled from the discharge sleeve 12, the spill valve 30 is closed by the operation of the drive mechanism. As shown in Figure 4, the spill valve 30 is closed by moving it outwardly until the spill hole 28 is sealed and the inner end 36 of the valve 30 is aligned with the inner surface of the circumferential wall 22. In this point, the molten metal M will fill the inner hole 20 to the bottom of the spill hole 28. Next, the piston 14 is advanced by the operation of the hydraulic cylinder. As the piston advances, it forces the molten metal M from the internal hole 20 into the die cavity (not shown). Once the piston 14 is fully extended, the molten metal M is allowed to cure. Optionally, high pressure can be developed in the molten metal for pressure casting. After the article is sufficiently cured, the piston 14 is retracted by operation of the hydraulic cylinder and the die assembly is open to remove the cast or cast article. The empty die assembly is then closed to prepare the system for the next discharge.

ALTERNATIVE MODALITY An alternative embodiment of the present invention is illustrated in Figure 5. In this embodiment, the spill hole 28 'extends through the circumferential wall 22' of the discharge sleeve 12 ', along an approximately inclined axis 40. degrees of the horizontal. Likewise, the spill valve 30 'is mounted for reciprocal movement parallel to the axis of the spill hole 28'. When opened, the spill valve 30 inclined provides a relatively open flow path 38 ', which is not obstructed by the inner end 36 of the valve. The above descriptions are those of the preferred embodiments of the invention. Various alternatives and changes may be made without departing from the spirit and broader aspects of the invention as defined in the appended claims, which are to be construed in accordance with the principles of patent law including the doctrine of equivalents. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, property is claimed as contained in the following:

Claims (20)

1. A discharge sleeve system for a pressure casting apparatus, characterized in that it comprises: a discharge sleeve having a circumferential wall defining an internal orifice and a leak orifice; a piston means for ejecting the molten material from the discharge sleeve, the piston means mounted for reciprocal movement within the internal bore; a spill valve movable between an open position, in which the internal orifice is in external communication through the spill hole and a closed position in which the spill valve closes the spill orifice; and a drive means for moving the spill valve between the open position and the closed position.

2. The discharge sleeve system according to claim 1, characterized in that the spill valve includes a first portion corresponding in cross section to the spill hole and a second portion having a cross sectional area smaller than that of the spill orifice. , the valve is movable in a linear direction between (a) an open position in which the second portion forms a bridge with the circumferential wall to define a flow path and (b) a closed position in which the first position is placed inside the spill hole to seal the spill hole.

3. The discharge sleeve system according to claim 2, characterized in that the circumferential wall includes an inner surface having a contour, the spill valve includes an inner end shaped to engage the contour of the inner surface, the inner end in alignment with the inner surface, when the spill valve is in the closed position.

4. The discharge sleeve system according to claim 3, characterized in that the spill orifice is circular in cross section and the first portion of the valve is circular in cross section.

5. The discharge sleeve system according to claim 4, characterized in that the spill valve includes a lower part, a second portion defining a slot extending longitudinally along the lower part of the valve.

6. The discharge sleeve system according to claim 5, characterized in that the groove is defined by an upper wall and a pair of opposite side walls, the side walls are obtuse with respect to the upper wall.

7. The discharge sleeve system according to claim 6, characterized in that the spill orifice extends along a generally horizontal axis.

8. The discharge sleeve system according to claim 6, characterized in that the spill hole extends along an axis inclined upwards towards the internal orifice.

9. A discharge sleeve for supplying molten material to a cavity, characterized in that it comprises: a circumferential wall defining an internal orifice and a pouring orifice in communication with the orifice, the circumferential wall further defining a spill orifice extending completely through from the wall, the spill hole is placed below the pouring hole; a spill valve mounted within the spill hole for linear, selective movement between a closed position in which the valve seals the spill hole and an open position in which the spill hole remains open, such that the orifice internal is in external communication through the spill hole; and actuating means for selectively moving the spill valve between the open position and the closed position.

10. The discharge sleeve according to claim 9, characterized in that the spill valve includes a first portion that corresponds in cross section to the spill hole and a second portion having a cross sectional area, smaller than that of the spill hole, the valve is movable in a linear direction between (a) an open position in which the second portion forms a bridge with the circumferential wall, to define a flow path and (b) a position closed in which the first portion is placed within the spill hole to close and seal the spill hole.

11. The discharge sleeve according to claim 10, characterized in that the circumferential wall includes an inner surface having a contour, the spill valve includes an inner end shaped to engage the contour of the inner surface, the inner end in alignment with the inner surface, when the spill valve is in the closed position.

12. The discharge sleeve according to claim 11, characterized in that the spill hole is circular in cross section and the first portion of the valve is circular in cross section.

13. The discharge sleeve according to claim 12, characterized in that the spill valve includes a lower part, the second portion defining a slot extending longitudinally along the lower part of the valve.

14. The discharge sleeve according to claim 13, characterized in that the slot is defined by an upper wall and a pair of opposite side walls, the side walls are obtuse with respect to the upper wall.

15. The discharge sleeve according to claim 14, characterized in that the discharge sleeve includes a piston end and the leak orifice is near the end of the piston.

16. An apparatus for die casting, characterized in that it comprises: a die assembly having a plurality of matrix elements cooperating to define a die cavity; a discharge sleeve mounted to the die assembly, the discharge sleeve defines an internal hole in communication with the die cavity and includes a spill means to allow the molten material to spill out of the discharge sleeve once a volume The desired amount of molten material is contained within the discharge sleeve; a spill valve means for selectively opening and closing the spill means, to selectively prevent the molten material from spilling from the discharge sleeve by means of the spill; and a piston means for expelling the molten material from the discharge sleeve into the die cavity, the piston means mounted for reciprocal movement within the internal orifice of the discharge sleeve.

17. A method for melting under pressure, characterized in that it comprises: retracting a piston from a discharge sleeve; introducing the molten material into the discharge sleeve through a discharge orifice, until the molten metal is above a spill hole in the side of the sleeve; allow excess material to spill from the sleeve through the spill hole; close the spill hole; and advancing the piston inside the sleeve 1e to discharge the molten material from the discharge sleeve.

18. The method according to claim 17, further characterized in that it comprises the steps of: closing the spill valve before the introduction step; waiting a predetermined period of time for the molten material to level out after the introduction step; and open the spill valve between the waiting and operating stages.

19. The method according to claim 18, characterized in that the spill valve includes a first portion corresponding in cross section to the spill hole and a second portion having a cross sectional area smaller than that of the spill orifice; the closing step which is defined by the movement of the spill valve, such that the second portion forms a bridge with the circumferential wall to define a flow path; and the opening step which is defined by the movement of the spill valve, such that the first portion is positioned within the spill hole to seal the spill hole.

20. An apparatus for melting under pressure, characterized in that it comprises: a discharge sleeve defining a discharge orifice and a spill orifice, the discharge orifice is at a level higher than the effusion orifice; an alternating piston inside the sleeve; and a valve means for selectively opening and closing the spill orifice.