US3809531A - Die casting apparatus - Google Patents

Abstract

The invention relates to heater apparatus for controlling the temperature of the melt within the nozzle or transfer tube of a die casting machine. The apparatus employs thermostaticallycontrolled heated gases which flow into an enclosure surrounding the nozzle, maintain the nozzle within a predetermined temperature range, and are either exhausted from the enclosure or are recycled back to the heater. The enclosure includes a damper deflector and walls which are readily retractable for access to the nozzle.

Description

United States Patent 1191 Jones [111 3,809,531 145 May 7, 1974 DIE CASTING APPARATUS Melvin A. Jones, Lake Mohawk R.R. No. l, Tiffin, Ohio 44883 Filed: June 4, 1973 Appl. No.: 366,645

Inventor:

U.S. c1.....-.. 432/225, 432/227 161. c1. F27b 9/36 Field 61 Search 432/222, 225, 226, 227,

432/219; 164/250; l8/DIG. 39

References Cited UNITED STATES PATENTS 12/1972 Mulhall 432/219 9/1969 Blinne 432/225 9/1965 Bennett et al. 432/219 Primary Examiner-John J. Camby Attorney, Agent, or Firm-Thomas M. Freiburgcr;

Richard D. Emch; Owen & Owen [5 7] ABSTRACT The invention relates to heater apparatus for control ling the temperature of the melt within the nozzle or transfer tube of a die casting machine. The apparatus employs thermostatically-controlled heated gases which flow into an enclosure surrounding the nozzle, maintain the nozzle within a predetermined temperature range, and are either exhausted from the enclosure or are recycled back to the heater. The enclosure includes a damper deflector and walls which are readily retractable for access to the nozzle.

7 Claims, 4 Drawing Figures 1 DIE CASTING APPARATUS BACKGROUND OF THIE INVENTION Various means have been employed for controlling the melt temperature within the nozzle of a hot chamb er die casting machine. One of these prior art means is a set of electric resistance heaters or Calrods encased in a clamshell type device which surrounds the nozzle. There are many disadvantages to the use of these'devices.

The electric resistance units are not responsive to the need for frequent access to the nozzle in that they are generally not readily removable from around the nozzle. They are quite fragile and tend to develop breaks after repeated removal and replacement.

Another disadvantage of the electric resistance units is their slow response to the changing demands of the nozzle for heat. In addition, the units tend to result in quite localized heating of the nozzle with much local overheating, so that the temperature of the melt is not evenly controlled and the nozzle itself is subjected to considerable stresses. These stresses weaken the nozzle and eventually cause cracks and breaks which shorten nozzle life and create a safety hazard for those in the vicinity.

Another prior art means of maintaining nozzle temperature control is the use of a blow torch. Not only does the blow torch, like the electric units, tend to result in uneven heating, but it is'also generally quite unwieldly and somewhat hazardous. This form of heating also tends to erode the nozzle. Bends or cracksmay develop due to the unevenness of the application of the heat, and often a torch left unattended will actually melt a portion of the nozzle. Accordingly, the operator generally does not leave the vicinity of the nozzle with a torch in operation.

SUMMARY OF THE INVENTION The present invention provides an improved heater apparatus or nozzle melt control for a die casting machine virtually free of the disadvantages inherent in prior art nozzle heaters. The invention employs thermostatically-controlled hot gases which enter the vicinity of the nozzle or transfer tube, evenly maintain the nozzle within a predetermined temperature range, and then either pass into the surrounding air or return to the heater. The heating of the gas is accomplished by means of a hydrocarbon fuel burning device which is thermostatically controlled. The hot gas is led to the exterior of the nozzle through a conduit that terminates in an enclosure surrounding the nozzle.

In addition to containing the hot gases, the enclosure provides a safety shield which will block the ejection of molten metal in the event of a failure of the nozzle. Within the enclosure is a thermocouple which is connected to the thermostat control of the combustion chamber. The system preferably includes a blower, which may be of the variable speed type, for frocing the hot gases to the enclosure. The enclosure also includes a damper-like deflector for adjusting the distribution of the hot gases around various portions of the nozzle. For example, during a period when the hot chamber die casting machine is inactive use, it may be desirable to deflect most of the hot gas to the end of the nozzle adjacent the dies, because the melt in the other end of the nozzle will be kept relatively hot from the repeated the length of the hozzle.

flow of the melt from the gooseneck or the pot. Conversely, if the die casting apparatus is inactive or in infrequent use then a more equal distribution over the length of the nozzle is more desirable.

The nozzle enclosure includes retractable side an end portions adjacent the nozzle for quick and easy access to the nozzle. These retractable portions are preferably hinged and when in closed position are retained together by use of spring clamp fasteners of the toggle action type. This accessibility feature of the present invention provides'an advantage over prior art calrod type nozzle heaters, which are normally not easily removed and replaced.

The enclosure provides several exhaust ports through which the hot gases exit after their communication with thenozzle or transfer tube. Preferably an exhaust port is located in each end of the enclosure, concentric with a haust ports, together with the damper-like deflector,

helps facilitate even heat applicationaround the periphery of the nozzle with the desired distribution along The end exhaust ports facilitate distribution of hot gases to portions of the nozzle beyond the enclosure and beyondareas reachable by prior art resistance unit heaters. The gooseneck itself, above the surface of the melt in the pot, requires heat in some circumstances to prevent freezing of the melt in that area. The present heater can provide such heating'by directing gases out the exhaust port in the direction of the nozzle. Satisfactory resistance unit type heaters have not been available for this purpose. Essentially the only method of remelting metal in the gooseneck has been by means of the torch with its above-discussed disadvantages.

Similarly, the opposite end of the nozzle may be heated in its entirety, through the platen and up to the die cavity. This is possible because of the ability of hot gases to flow in a tortuous path and generally wherever they are directed. Conventional resistance unit heaters could not be placed on this extremity because of lack of space around the nozzle. Because the present heater with its end exhaust ports is capable of directing hot gases to areas far beyond the limits of its enclosure, it is especially versatile in being applicable to a relatively wide range of nozzle lengths.

For different nozzle diameters, the heater apparatus may be provided with various side and end portions, re-

movable at the hinges, so that the end exhaust ports may be of suitable diameter with predetermined opening area.

When the enclosure includes exhaust ports as discussed above, the hot gas medium is preferably air.

However, it is sometimesdesirable to recirculate the gas rather than exhausting hot gases in the vicinity of the die casting machine. In that case, the exhaust ports are replaced by conduits leading back toward the combustion chamber. The system is then substantially 7 closed and can be charged witheither air or any other I BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 diagrammatically indicates a hot chamber submerged plunger die casting apparatus with a nozzle heated by heater apparatus according to the present invention; 7

FIG. '2 is a sectional view of a nozzle enclosure portion of the present invention taken along the line 2-2 of FIG. 1; I

FIG. 3 is a partially sectioned, diagrammatic elevational view of a vertical cold chamber type die casting apparatus in which an embodiment of the invention is employed to maintain the melt in the transfer tube within a predetermined temperature range; and

FIG. 4 is a partially sectioned diagrammatic side view of a heater apparatus embodying the instant invention and including a recirculating means.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 indicates a hot chamber die casting machine including a nozzle heated by a heater apparatus embodying the present invention and generally indicated by the reference number 10. The heater apparatus is constructed almost entirely of sheet metal. The apparatus 10 includes a blower 11, preferably of the variable speed type. Makeup air is forced through a burner chamber generally indicated by the reference number 12, preferably a natural gas burner. Other types of heating means may be used in the chamber 12, for example, electrical resistance type units. The burner is controlled by a thermostat control 13 and may be set at various temperature levels. From the burner chamber, 12, the heated air passes through an angled conduit 14 and into a nozzle enclosure 15-which is spaced from a nozzle 16. The angled conduit 14 may be replaced by a straight conduit 17, depending upon the positioning of the nozzle 16. As the air enters the enclosure 15, it passes over a thermocouple sensor 18 to which the thermostat control 13 is responsive.

As shown in FIGS. 1 and 2, the enclosure 15 provides a continuous bath of hot air enveloping andevenly heating thenozzle 16. Tapered end portions 19 and 20 and exhaust ports 21 and 22 assure that the distribution of hot air includes the extremities of the nozzle 16.

Spacers 23' at several points around the circumference of the exhaust ports 21 and'22 assure equal peripheral spacing from the nozzle 16, and thus even flow over-the portions of the nozzle 16 outside the enclosure 15. In order that the distribution of hot air may be varied along the length ofthe nozzle 16, a variable damper deflector 24 is included within the enclosure 15. The deflector 24 is preferably manually operated but may include automatic adjusting means (not shown) sensitive to changes in temperature along the length of the nozzle l6.

The enclosure 15 has retractable side portions 25 and 26 and retractable end flaps 27 and 28, all of which are preferably pivotally retained to an upper portion 29 of the enclosure 15 by hinges 30. Toggle action spring clamp fasteners 31 provide readily removable fastening means. The side portions 25 and 26 include exhaust ports 32 below the nozzle 16 to supplement the exhaust ports 21 and 22 defined by the end portions 19 and 20.

Referrin g'to FIG. 3, another embodiment of heater apparatus 10a is shown in connection with a vertical cold chamber type die casting machine generally indicated by the reference number 33. The machine 33 employs a vacuum to move the molten metal 34 from the pot 35 through the transfer tube 36 and into the shot sleeve 37. In the claims the term nozzle is utilized in its generic sense to include melt conduits such as the transfer tube 36. The heater apparatus 10a has a straight conduit 17 rather than the angled conduit 14 of FIG. 1. The heater apparatus 10a is used to maintain the molten metal '34 in, the transfer tube 36 within a predeterminedtemperature range. It will be appreciated that the embodiments are applicable to any die casting machine wherein molten metal is moved from a pot through a transfer tube or nozzle and ultimately into a die cavity.

In FIG. 4 a heater apparatus 38, embodying the'invention, is shown with recirculating means generally indicated by the reference number 39. This embodiment includes recirculation ports-40 and'41 in an enclosure 42 rather than the exhaust ports 21, 22, and 32 of the enclosure 15 of the FIG 1 embodiment. Each tapered end portion 43 of the enclosure 42 is fitted to closely circumscribe the nozzle or transfer tube 44 and may include a ring of asbestos 45 to sealingly enclose the nozzle or transfer tube '44. The recirculating conduit 38 preferably includes detachable joints 46 and pivotal joints 47 so that the hinged side portions 48 re main readily retractable for access to the nozzle or transfer tube 44. The conduit 39 has valving means 49 and 50 whereby the volume of recirculated gases may be varied, with a portion of the gases being recirculated to the burner chamber and the remainder discharged to the atmosphere.

The above described preferred embodiments provide a heater apparatus or a melt control system. capable of evenly heating a nozzle or transfer tube and the melt therein and maintaining them within a predetermined temperature range. The system provides easy access to the nozzle and is safe, compact, efficient, and economii cal. Various other embodiments and changes to the preferred embodiments described above will be apparent to those skilled in the art,and may be made without departing from the spirit and scope of the following claims.

What I claim is:

1. Heater apparatus for use with a die casting machine having a nozzle for transmitting the melt to the dies, said heater apparatus comprising heating means for heating a gas, enclosure means surrounding and spaced from the nozzle for effecting fluid communication between the heated gas and the nozzle and even heating around the nozzle, adjustable means within said enclosure means for selectively distributing the'hea'ted gas along the nozzle, a conduit extending between said heating means and said enclosure means defining a path of gas travel, blower means in communication with said conduit for transferring the gas from said heating means to said enclosure means, means for disposing of the gas after its communication with the nozzle, and means for regulating the temperature ofthe gas within said enclosure means.

2. Heater apparatus according to claim I wherein I said adjustable means comprises a damper deflector pivotally mounted within said enclosure means adjacent said conduit in the path of gas travel.

munication betweenthe gas and the nozzle outside said enclosure means.

6. Heater apparatus according to claim 1 wherein said gas disposing means includes means for recirculating the gas from said enclosure means to said heating means.

7. Heater apparatus according to claim 6 wherein said gas recirculating means comprises a returngas conduit leading from said enclosure means to said heating means.

Claims (7)

1. Heater apparatus for use with a die casting machine having a nozzle for transmitting the melt to the dies, said heater apparatus comprising heating means for heating a gas, enclosure means surrounding and spaced from the nozzle for effecting fluid communication between the heated gas and the nozzle and even heating around the nozzle, adjustable means within said enclosure means for selectively distributing the heated gas along the nozzle, a conduit extending between said heating means and said enclosure means defining a path of gas travel, blower means in communication with said conduit for transferring the gas from said heating means to said enclosure means, means for disposing of the gas after its communication with the nozzle, and means for regulating the temperature of the gas within said enclosure means.

2. Heater apparatus according to claim 1 wherein said adjustable means comprises a damper deflector pivotally mounted within said enclosure means adjacent said conduit in the path of gas travel.

3. Heater apparatus according to claim 1 wherein said enclosure means includes retractable portions for providing ready accessibility to the nozzle.

4. Heater apparatus according to claim 3 wherein said retractable portions are hinged.

5. Heater apparatus according to claim 1 wherein said enclosure means includes forward and rearward end portions circumscribing the nozzle and wherein said gas disposing means comprises exhaust ports, at least one of which is positioned peripheral to the nozzle in one of said end portions for effecting further communication between the gas and the nozzle outside said enclosure means.

6. Heater apparatus according to claim 1 wherein said gas disposing means includes means for recirculating the gas from said enclosure means to said heating means.

7. Heater apparatus according to claim 6 wherein said gas recirculating means comprises a return gas conduit leading from said enclosure means to said heating means.

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