DELIVERY DEVICE FOR A METAL BATH IN A DIECASTING UNIT

Abstract

A feed device for a metal melt in an injection molding device of, for example, a metal-molding machine has a reservoir for the metal melt and a feed duct, in which the metal melt can be fed to a mold cavity. The feed duct includes a cylinder bore, in which a piston is arranged axially displaceably. A collection chamber for the metal melt, from which the metal melt can be introduced into the mold cavity through a continuing line as a consequence of an axial displacement of the piston, is provided in the cylinder bore. The cylinder bore is surrounded by a first heater, which has at least one heating element.

Claims

1. A feed device for a metal melt in an injection molding device, the feed device comprising: a reservoir for the metal melt; a continuing line; a feed duct, in which the metal melt can be fed to a mold cavity, wherein the feed duct comprises: a cylinder bore a piston is arranged axially displaceably in the cylinder bore, and wherein a collection chamber for the metal melt, from which the metal melt can be introduced into the mold cavity through the continuing line as a consequence of an axial displacement of the piston, the collection chamber being provided in the cylinder bore; a heater, wherein the cylinder bore is surrounded by a the heater, which heater has at least one heating element; a piston driving device and/or a control device at an end of the piston facing away from the collection chamber; a cooling device associated with the driving device and/or the control device such that the piston driving device and/or a control device is cooled by the cooling device; and a partition through which the piston passes, wherein the partition is provided between the heater and the cooling device.

2. A feed device in accordance with claim 1, wherein the partition is cooled by the cooling device.

3. A feed device in accordance with claim 1, wherein the heater comprises at least another heating element to provide a plurality of heating elements arranged distributed over a circumference of the cylinder bore.

4. A feed device in accordance with claim 3, wherein the heating elements are heating cartridges extending at radially spaced locations from and parallel to the cylinder bore.

5. A feed device in accordance with claim 3, wherein the plurality of heating elements comprises four to eight heating elements.

6. A feed device in accordance with claim 3, wherein the heating elements can be actuated individually and/or in groups.

7. A feed device in accordance with claim 1, further comprising a valve rod and a valve rod driving device, wherein the piston has an axial hole, in which the valve rod is received displaceably, the valve rod is operably connected to the valve rod driving device at an end of the valve rod facing away from the collection chamber and the valve rod driving device and/or the control device are cooled by the cooling device.

8. A feed device in accordance with claim 1, wherein the cooling device comprises at least one cooling duct, through which a cooling fluid flows.

9. A feed device in accordance with claim 1, wherein the metal melt can be maintained in the reservoir under a protective gas atmosphere.

10. A feed device in accordance with claim 1, further comprising another heater associated with the reservoir of the metal melt.

11. A feed device in accordance with claim 10, wherein a nonreturn valve is arranged in the continuing line and a further heater (44) is associated with the nonreturn valve.

12. A feed device in accordance with claim 1, wherein a nonreturn valve is arranged in the continuing line and a further heater is associated with the nonreturn valve.

13. A feed device in accordance with claim 8, wherein the cooling fluid is a cooling liquid.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In the drawings:

[0023] FIG. 1 is a longitudinal sectional view through a feed device according to the present invention; and

[0024] FIG. 2 is an enlarged perspective view of the cylinder bore with a heater arranged on the outside.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Referring to the drawings, a feed device 10 for a metal melt M in an injection molding device, which feed device is shown in FIG. 1, has a housing 11, in which a vertical receiving hole 12 is formed.

[0026] A reservoir 26, which is filled with the metal melt M, is provided in the housing 11. The metal melt M may be fed to the reservoir 26 in the molten form or produced in this by melting, for example, metal granules.

[0027] The reservoir 26 is covered airtightly by means of a cover part 45 and the free space 46 formed above the metal melt M in the reservoir 26 is filled with a protective gas, for example, carbon dioxide (CO.sub.2) or nitrogen (N.sub.2).

[0028] A second heater 43, which may be an electrical resistance heater and with which the wall of the reservoir 26 and hence the metal melt M can be brought to a desired temperature or maintained at such a temperature, is integrated in the housing 11 in the area of the reservoir 26.

[0029] Via at least one feed channel 18 extending with a downward slope in the flow direction, the reservoir 26 is in connection with the receiving hole 12. An adapter 28, which has a tubular configuration and is closed at its lower end, is inserted with close fit into the receiving hole 12. The adapter 28 is held replaceably in the receiving hole 12 and has a central axial cylinder bore 27, which is configured in the form of an upwardly open blind hole. An obliquely extending connection hole 30, which is flush with the feed duct 18 and connects same with the cylinder bore 27, is provided in the wall of the adapter 28.

[0030] A piston 13 is displaceably inserted into the cylinder bore 27 with close fit. An annular space 17 is formed on the outside of the piston 13 in an area, which is arranged in the lower half of the axial length of the piston 13 and which is located at an axially spaced location from the lower end of the piston 13. A plurality of filling holes 16, arranged distributed over the circumference of the piston 13, extend in the piston 13 towards the lower end face of the piston 13 at the lower end of the annular space 17. The area of the piston 13 in which the filling holes 16 are formed is in contact in a sealed manner with the inner wall of the cylinder bore 27.

[0031] Two circumferential grooves 29, which are located at axially spaced locations and into which a slotted piston ring 31 each is inserted, are formed on the outer jacket surface of the piston 13, said piston ring 31 being sealingly in contact with the inner wall of the cylinder bore 27 under a spring tension directed radially outwardly against the inner wall of the cylinder bore 27. The piston rings 31 consist, for example, of a spring steel.

[0032] The piston 13 further has a central axial hole 14, in which a valve rod 19, which passes completely through the piston 13 and carries a plate-shaped valve body 20 at its lower end downstream of the end face of the piston 13, is arranged displaceably. By displacing the valve rod 19 relative to the piston 13, the valve body 20 can be adjusted between a closed position shown in FIG. 1, in which the valve body 20 prevents metal melt from flowing out of the filling holes 16, and an open position, not shown, in which the metal melt can flow from the filling holes into a collection chamber 15, which is located under it and is formed in the cylinder bore 27.

[0033] The cross section of the valve body 20 is smaller than the cross section of the cylinder bore 27, so that the valve body 20 has a sealing function within the cylinder bore 27 and the metal melt M can flow freely around the valve body 20.

[0034] A pressure sensor 49, which is only suggested and sends a pressure signal via a line to a control device, not shown, which controls the drive of the piston 13, is arranged in the collection chamber 15. A control circuit is thus obtained for the drive (hydraulic cylinder) of the piston 13.

[0035] The cylinder bore 27 or the collection chamber 15 formed in its lower area is connected to a mold cavity, not shown specifically, via a continuing line 21. The continuing line 21 comprises a lower cross hole 32 in the wall of the adapter 28, which cross hole is flush with a continuing cross hole 33 in the housing 11, via which the collection chamber 15 is connected to a vertical riser 22 via said cross hole 33. The riser 22 passes over at its upper end into a filling duct 23, from which the metal melt is fed to the mold cavity, as is indicated by the arrow F. A nonreturn valve 24, which has a valve body 25, which is tensioned by a spring 34 against the flow direction against a valve seat 35, is arranged in the transition between the riser 22 and the filling duct 23.

[0036] The cylinder bore 27 and the adapter 28 are surrounded by a first heater 36, which has a plurality of heating elements 37, which are arranged distributed over the circumference of the adapter 28 and are each inserted into a hole formed in the housing, as is indicated by broken line in FIG. 1. The arrangement of the heating elements 37, which are preferably electrical heating cartridges, is shown in FIG. 2. It is seen from this that six heating elements 37 are provided, which are distributed uniformly over the circumference of the adapter 28 and can preferably be actuated each individually or in groups. It is possible by means of the heater 36 to bring the metal melt M to a desired temperature or to maintain it at that temperature in the area of the connection hole 30, the filling holes 16, the collection chamber 15 and, at least in some sections, in the continuing line 21.

[0037] As is suggested in FIG. 1, a third heater 44, with which the temperature of the metal melt, which flows through the nonreturn valve 24, is controlled, especially within the nonreturn valve 24, is associated with the nonreturn valve 24. The third heater 44 may be formed by an electrical resistance heater or heating ducts, through which a hot fluid and especially a hot liquid flows.

[0038] The end of the piston 13 and of the valve rod 19 facing the collection chamber 15 is arranged in a drive and control housing 47, which is arranged on the outside of the housing 11 and in which a driving device 38, only suggested, for the piston 13 and a valve rod driving device 41, which are likewise only suggested and with which the piston 13 or the valve rod 19 are axially adjustable, are arranged. An electronic control device 48 is provided, likewise within the driving and control housing 47, especially for said driving devices, which is indicated only schematically. The drive and control housing 47 has, on its side facing the housing 11, a partition 40, through which the piston 13 and the valve rod 19 pass with a close fit and which is used as a heat shield.

[0039] A cooling device 39, which comprises a plurality of cooling ducts 42, through which a cooling liquid flows and extend through both the drive and control housing 47 and the partition 40, is further provided in the driving and control housing 47. It is possible by means of the cooling device 39 to maintain the interior space of the drive and control housing 47 and hence the driving device 38 for the piston 13, the valve rod driving device 41 and the electronic control device 48 at an advantageous operating temperature of preferably <80° C., because there is a risk due to the heater 36 that the components mentioned would otherwise become too hot and would be damaged as a result.

[0040] While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.