US3645319A

US3645319A - Method and apparatus for lubricating a closed die structure

Info

Publication number: US3645319A
Application number: US13289A
Authority: US
Inventors: William J Pondelicek; Vernon F Schmidt
Original assignee: HEICK DIE CASTING CORP
Current assignee: HEICK DIE CASTING CORP
Priority date: 1970-02-24
Filing date: 1970-02-24
Publication date: 1972-02-29
Anticipated expiration: 1989-02-28

Abstract

A method and apparatus for lubricating a die structure employed in diecasting operations, and die therefor, whereby a quantity of lubricant is injected under gas pressure into the die cavity, and in which the die may be provided with a chamber for receiving the die lubricant, which chamber communicates with the die cavity, the lubricant being discharged by gas under pressure into the die cavity, with the apparatus being constructed to effect discharge of lubricant into the chamber as the members of the die approach a closed position, and discharge of the lubricant into the die cavity when the die members are in a closed position.

Description

United States Patent Pondelicek et al.

[ Feb. 29,1972

[54] METHOD AND APPARATUS FOR Primary Examiner-Robert D. Baldwin LUBRICATING A CLOSED DIE Attorney-Hill, Sherman, Meroni, Gross & Simpson STRUCTURE [72] Inventors: William J. Pondelicek, Arlington Heights;

Vernon F. Schmidt, Chicago, both of ill. [57] ABSTRACT A method and apparatus for lubricating a die structure em- [73] Asslgnee' Huck Dle Cashng Corp" Chlcago ployed in diecasting operations, and die therefor, whereby a [22] Filed: Feb. 24, 1970 quantity of lubricant is injected under gas pressure into the die cavity, and in which the die may be provided with a chamber [21] Appl' 13389 for receiving the die lubricant, which chamber, communicates with the die cavity, the lubricant being discharged by gas [52] US. CL ..164/72, 25/DIG. 15, 164/267, under pressure into the die cavity, with the apparatus being 264/39 constructed to effect discharge of lubricant into the chamber [51] Int. Cl .3224! 17/20 as the members of the die approach a closed position, and Field of Search 184/ l R; 7/51, discharge of the lubricant into the die cavity when the die 117/ 2 1316- 16 members are in aclosed position.

[56] References Cited WWW V i E M mm-n UNITED STATES PATENTS i Dr g Figures 3,053,343 9/1962 Hornbostel 4 3,070,857 l/l963 Venus ..l64/347 X METHOD AND APPARATUS FOR LUBRICATING A CLOSED DIE STRUCTURE BACKGROUND OF THE INVENTION It is common practice in the use of diecasting equipment to attempt to apply a suitable lubricant to the surfaces defining the die cavity, thereby increasing the efficiency of the apparatus by a reduction in rejects and improvement in the ultimate casting of aluminum or other metal.

It has been common practice in the past for an operator to spray a solution of a lubricant onto the cavity surfaces of the open die structure between each die casting operation. Obviously no accurate control could be maintained over the amount of lubricant utilized or was there any way of governing the deposit and retention of the lubricant on the die surface. Invariably in such cases, an excessive amount of lubricant, as well as the necessary carrier agent therefor, were employed resulting in not only a waste of lubricant and solvents but the creation of a considerable amount of smoke and air pollution, which in fact is the greatest source of smoke and air pollution around a die casting machine. In the case of aluminum casting, the lubricant may comprise aluminum powder and silicones in a carrier agent as for example water, kerosene, or other suitable hydrocarbon solvents. Tests have indicated that with such types of carrying agents deposition of lubricant in an effectual layer did not take place until the cavity surface is suitably cooled to a temperature below 375 F. However, the chilling of the die considerably increases the possibility of poor casting and porosity, leading to a high reject percentage, and also results in a high thermal gradient in the steel die leading to early die fatigue.

The present invention thus is directed to a method and apparatus for effecting a very efficient lubrication of the die structure with an elimination of the disadvantages of prior practices.

SUMMARY OF THE INVENTION The invention proceeds from the direct opposite of prior methods efiecting lubrication when the die members are in open positions, and instead effects the coating of the die surfaces following closing of the die members, the method also having the very important advantage of not only effectively lubricating the surfaces of the die cavities but also the effective lubrication of ejector pins as well as any side cores, etc., and where the apparatus is employed in a cold chamber operation efficient lubrication of such sleeve and plunger tip is likewise achieved.

At the same time, the invention enables the utilization of substantially the exact amount of lubricating material necessary to achieve the desired results, the material being directly injected without the use of carrier agents, as in the past, to eliminate much of the smoke and air pollution previously occurring in the use of a die casting machine. As the lubricant is applied to the die surface when the die members are in closed position and no solvents are required, it has been found that efficient coating may be obtained at an optimum operating temperature of the die. Furthermore, as no solvents or other carriers are required and as optimum amounts of lubricant may be employed a considerable reduction in cost of lubrication may be achieved and at the same time eliminate need of additional lubricants for the metal injecting plunger, etc.

In the practice of the invention, utilizing the apparatus and die members such as illustrated in the drawings, the die member is provided with a chamber or passageway which communicates, preferably through a suitable valve, with the die cavity, means being provided for injecting a measured quantity of lubricant into such chamber or passageway as the die members approach a closed position and then upon closing thereof, a blast of a gas, for example air, is discharged, under pressure, into such chamber or cavity whereby the lubricant is expelled in a substantially completely vaporized form into the die cavity, reaching all surfaces of the latter, under the action of the gas pressure, as well as the ejector pins and the shot sleeve and plunger structure, etc.

In the apparatus illustrated, the die casting machine is provided with means responsive to closing movement between the platens of the machine to actuate the lubricant injection mechanism as well as control the gas discharge operative to transport the lubricant into the die cavity.

The present invention provides a method of lubricating an apparatus for practicing the method which is exceedingly simple in construction, readily adapted for employment on substantially any type of diecasting equipment, whether of the shot sleeve or hot chamber type, and provides a further mechanizing of an additional step in the diecasting cycle.

In many cases the invention will be readily applicable to existing dies by a relatively minor reworking thereof in accordance with the teaching of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings wherein like reference characters indicate like or corresponding parts,

FIG. 1 is a side elevational view, in generally schematic presentation of portions of a diecasting machine pertinent to an understanding of the invention;

FIG. 2 is a sectional view through one portion of a die structure, constructed in accordance with the present invention, schematically illustrating cooperable elements employed in the practice of the invention; and

FIG. 3 is a top plan view of the die structure illustrated in .FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION The invention will be described in three sections, the first dealing with the overall method thereof, the second a detailed description of a die member incorporating features of the invention and the last a detailed description of apparatus, utilizing such a die member, whereby the lubrication of the die will take place automatically in response to operation of other portions of the die casting machine. While any suitable gas, as for example an inert gas may be employed where deemed desirable, the invention will be described herein in conjunction with the use of compressed air as the gas source, which it is believed will be suitable for at least most of the applications to which the invention may be employed.

The Method In utilization of the method of the invention, a desired quantity of the lubricant to be employed, in concentrated, undiluted form, is injected into the die cavity by a measured blast of gas, for example compressed air, of sufficient quantity and of sufficient duration to ensure effective vaporization and distribution of the lubricant over all of the surface area of the die cavity, sufficient lubricant normally being injected to also ensure suitable lubrication of the ejector pins as well as desired components of the metal injecting structure of the die casting machine, as for example the shot sleeve and plunger of such a machine.

It is believed apparent that as the amount of lubricant may be accurately measured to achieve lubrication of substantially only desired areas and structure, and the lubricant may be directly used without additional solvents or carrier agents, smoke and air pollution will be materially reduced to a minimum, at the same time providing maximum lubrication efficiency. stationary The General Apparatus Referring to FIG. 1, the reference numeral 1 designates a die structure, illustrated as being of relatively simple fonn and comprising a pair of die members 2 and 3, the stationary die member 2 being carried by a stationary platen 4 rigidly mounted on the bed of the machine, and the ejector die member 3 being rigidly carried by a movable platen 5 slidable The die members 2 and 3 are adapted to cooperate to define a die cavity 8, a portion of which is illustrated in FIGS. 2 and 3, with suitable communication being provided between such die cavity and a shot sleeve indicated generally by the numeral 9, the sleeve having an opening therein communicating with the interior of the sleeve and thus with the die cavity, a suitable piston, not shown being reciprocably movable in the sleeve by means of a reciprocable rod 11. In operation of the mechanism thus far described, the arrangement will normally be such, with respect to the metal supply system of the die casting machine that the port 10 in the shot sleeve is open to the atmosphere when the rod 11 and thus the piston carried thereby is in its extreme left-hand position, as viewed in FIG. 1. At the proper time the molten aluminum or other metal is supplied to the shot sleeve through the opening 10 and the rod 11 and piston associated therewith moved toward the right as viewed in FIG. 1 to inject metal into the die cavity, the initial movement of the piston closing the port 10. In this type of casting operation the amount of metal will likewise normally be apportioned to ensure complete filling of the die cavity with a minimum of excess metal.

In the embodiment of the invention illustrated, mounted on the movable platen 5 is a lubricant container 12 adapted to contain a supply of die lubricant under pressure, created, for example, by means of a compression spring 13 disposed within the container 13, bearing upon a disk 14 adapted to apply pressure to a supply of lubricant contained at the bottom of the container 12. Supplementing or in place of the springs 13, the lubricant supply may be placed under pressure, for example by means of air pressure present in a supply conduit 15, the air pressure in which may be reduced by a suitable reducing valve 16, communicating by means of a conduit 17 with the upper portion of the container 12. Carried by the stationary die member 2 is a lubricant-metering device 18, the inlet side of which communicates with the reservoir 12 through a supply conduit 19. The device 18 illustrated is adapted to be operated by air pressure supplied thereto from a supply line 20 which is connected to the device 18 by a conduit 21 through a control valve 22. The valve 22 is adapted to be actuated by a one-way cam 23, carried by the movable platen, which is adapted to actuate the valve 22 in the closing direction of the platen, i.e., from right to left as viewed in FIG. 1 but not in the opposite direction. As illustrated, the cam 23 may be adjustably mounted on the platen 5 to enable actuation of the valve 22 at the desired point of time in the operational cycle of the machine.

Lubricant injected into the die structure from the metering device 18 is adapted to be exhausted into the die cavity thereof by means of air pressure through a supply line 24 under control of a pilot valve and timer 25 which is adapted to be pneumatically actuated by air from the supply line 26 under control of an electrically operating valve 27 which in turn is adapted to be actuated by a switch 28 having an actuating arm 29 engageable with an elongated cam member 30 carried by the movable platen 5.

The valve and timer 25 is of commercially procurable construction and incorporates a valve structure which is pneumatically opened and automatically closed after a predetermined time interval. Thus, upon operational engagement of the cam member 30 with the arm 29 to actuate the switch 28, the valve 27 is opened to supply actuating air to the pilot valve 25, thereby opening the same and permitting air from the conduit 24 to enter the die and thereby exhaust vaporized lubricant, discharged from the metering device 18, into the die cavity. At this point in the operation the actuating rod 11 and piston associated therewith are in a position to open the port 10 and thereby provide a pressure release for any air exhausted into the die cavities through the valve 25.

Thus, each time the platen 5 and the die member 3 carried thereby are moved from open position in a closing direction, i.e., to the left as viewed in FIG. 1, as the die member 3 approaches closing position with the die member 2, the valve 22 will be actuated by the cam 23 to supply actuating air to the metering device 18 and inject a desired quantity of lubricant into the die structure. Following this operation, when the die reaches a closed position the cam member 30 will effect actuation of the switch 28 and thereby the valve 27 and valve 25 to produce an air discharge into the die cavity, resulting in dis tribution of the lubricant throughout the latter as well as the shot sleeve 9, any air pressure being relieved through the port 10. Following this operation a measured quantity of molten metal is introduced into the shot sleeve 9 and the rod 11 and associated piston actuated to force the metal into the die structure. The movable platen 5 is subsequently actuated to open the die, permit removal of the casting and the initiation of a new cycle.

The Die Structure FIGS. 2 and 3 illustrate an example of a die structure embodying the invention, more particularly the cover die 2 illustrated in FIG. 1, only the portions of the die involving the present invention being illustrated.

In this particular embodiment, the die member 2 comprises a base portion or block 31 and an insert 32 having the die cavity 8 associated therewith. If deemed necessary or desirable the insert 32 may be provided with fluid cooling passages 33 in accordance with known die casting techniques.

In the embodiment illustrated the insert 32 is provided with an overflow well 34, in accordance with present techniques, and communicating with the well 34 is a bore 35 which terminates in a counterbore 36 extending through the adjacent wall of the base member 31 into the adjacent portion of the insert 32. The bore 35 terminates adjacent the well 34 in a valve seat 37. Cooperable therewith is a complementary shaped valve 38, provided with a valve stem 39 extending from the valve member 38 through the bore 35 into the counterbore 36. The valve is biased in a normally closed position by means of a compression spring 40, one end of which bears upon shoulder at the bottom of the counterbore and the opposite end on a lock ring 41 carried in a groove on the valve stem 39. The upper portion of the valve stem 39, as viewed in FIG. 2, i provided with flats 42 whereby the adjacent portion of the valve stem is of generally rectangular cross section and of lesser area than the enlarged lower end forming a chamber extending generally concentric with the valve stem and communicating at its lower end with a counterbore 36. The insert 32 is provided with a small bore 43 extending transversely to the axis of the bore 35 and intersecting the same adjacent the upper portion of the valve stem, such bore being operatively connected by suitable means, such as a conduit 44, with the lubricant metering device 18. The base block 31 is also provided with a bore 45, intersecting the counterbore 36, and thus in communication with the chamber defined by the bore 35, with the outer end of the bore 45 being operatively connected with the air pilot valve 25, for example, by suitable conduit means 46. In actual practice the metering device 18 and air valve 25 may conveniently be mounted directly on the base block 31. The outer end of the counterbore 36 is suitably sealed, for example, by means of a cover plate 47 secured in place by a plurality of screws 48.

In operation, lubricant is injected into the chamber defined by the bore 35 through the bore 43 and thereafter air, under pressure, is admitted through the bore 45 into the counterbore 36 operative to move the valve 38, in opposition to the spring 41, into open position to vaporize and discharge the previously deposited lubricant into the die cavity.

Operation of the Apparatus The overall operation of the apparatus illustrated in the drawings is as follows:

Assuming that the die members 2 and 3 are in closed position and the die cavity has been filled with metal, following solidification of the metal the movable platen 5 is brought into a position opening the die structure to permit the casting to be removed therefrom.

A new cycle then begins with the movable platen 5 and the ejector die member 3 being moved to the left as viewed in FIG. 1, and as the die members approach their closed position the cam member 23 carried by the platen 5 will actuate the valve 22. Air is thereby admitted, under pressure, into the metering device 18 which will cause the latter to inject a measured amount of lubricant into the chamber defined by the bore 35 of the die insert 32. As the die member 3 reaches closed position, the cam rod 30, through the actuating member 29, will actuate the switch 28. Valve 27 is thereby opened to admit air under pressure to the pilot valve 25 causing the latter to open and admit air from the supply conduit 24 into the counterbore 36 and bore 35, such air flow continuing for a predetermined time as set by the timer associated with the valve 25. At the expiration of such time period the valve 25 will close, shutting off the supply of air to the die.

During this operation the actuating rod 11 and piston associated therewith, disposed in the shot sleeve 9 will be in a position opening the port 10 whereby the discharged air will literally vaporize the lubricant ejected into the die cavity and distribute it quite uniformly over the entire surface of the die cavity as well as on the ejector pins and in the shot sleeve 9, with the air pressure being relieved through the port 10. Molten metal is then admitted through the port 10 into the shot sleeve and the plunger 11 actuated whereby the piston carried thereby forces the molten metal into the die cavity. Following solidification of the molten metal the die structure is open and the casting removed whereupon the mechanism is ready for the next cycle of operation.

It will be appreciated that the amount of lubricant, as well as the pressure and volume of air, as determined by the timer associated with the pilot valve, will vary with the size and shape of the die cavity and number of cavities, if more than one, and one skilled in the art will readily be able to determine the desired amount and operating values suitable to achieve optimum operation in any particular application. Thus, the amount of lubricant preferably should be reduced to merely that necessary to provide adequate lubrication, as heretofore discussed, with the pressure and volume of air employed being so selected that it is sufficient to insure efficient vaporization of the lubricant and transportation and deposition thereof on all the desired surfaces. It would appear that for most applications the air pressure may range between 40 and 150 lb. with the timer maintaining the air pressure for a duration of from 3 to 10 seconds. While the amount of lubricant will of course vary with the size and shape of the die, i.e., the surface area involved, the amount of lubricant will also depend upon the specific lubricant employed and the desired extent or thickness of the lubricant on the die surface. This can be readily determined by the operator, starting with an amount of lubricant approximately equivalent to the effective amount of lubricant previously employed in a spraying process or the like.

The invention is also applicable to so-called hot chamber machines by the addition of an automatic shutoff vent in or associated with the die. In this type of machine the additional vent is necessary as it does not utilize a shot sleeve structure or its equivalent which is open to the atmosphere prior to the injection of the metal. Consequently, the advantages of the invention can be readily achieved by providing a suitable socalled massive vent valve at an appropriate location to insure adequate relief of the air discharged into the die. Such a valve thus would permit pressure release with respect to the air but would remain closed during the pouring operation. Vent valves of this type are commercially available.

It will be apparent from the above disclosure that the present invention simultaneously substantially eliminates three serious problems in die casting practices, not only providing highly efficient low-cost lubrication of the die structure, but at the same time producing most immediate and dramatic results in the elimination of much of the smoke and air pollution found around die casting machines during previous types of lubricating cycles, and third, the very important ability to permit efficient lubrication of the die surfaces etc., at higher die surface temperatures. This, in turn, eliminates radical heat gradient in the die structure.

Having thus described our invention it will be obvious that various and material modifications may be made in the same without departing from the spirit 'of our invention, since we do not wish to be understood as limiting ourself to the exact form arrangement and combination of parts shown and described.

We claim:

1. A method of lubricating a closed die structure employed in diecasting operations, comprising the steps of measuring an amount of lubricant, sufficient to lubricate surfaces of such a die, and distributing said amount of lubricant over the surfaces of the die cavity by subjecting said lubricant to the action of a gas under pressure as the latter is selectively discharge into said die and through at least one passageway in said die operatively extending at such time from said cavity to exteriorly of the die for relief of pressure within the die resulting from said gas discharge.

2. A method according to claim 1, wherein said measured amount of said lubricant is disposed in a space adjacent to and adapted to communicate with the die cavity, and said gas under pressure is discharged into said space to discharge the lubricant therefrom into the die cavity.

3. A method according to claim 1, wherein said lubricant is in concentrated form and compressed air is utilized as the gas under pressure.

4. A method of lubricating a die structure, employed in die casting, comprising at least two separable die sections cooperable to form a mold cavity, comprising the steps of closing the die structure, injecting an amount of lubricant sufficient to lubricate desired surfaces of such die into a space adjacent to and communicatable therewith the die cavity prior to the die reaching a closed position, and upon complete closure of the die structure injecting said lubricant into the die cavity by selectively discharging a gas under pressure into said space and through at least one passageway in said die extending at such time from said cavity to exteriorly of the die for relief of pressure in the die resulting from said gas discharge, and upon desired relief of such gas pressure injecting a quantity of molten metal into the lubricated cavity.

5. A method according to claim 4, wherein said lubricant is in concentrated form and compressed air is utilized as the gas under pressure.

6. A die member constructed for cooperation with another die element to define a metal-receiving cavity, said die member having a chamber therein arranged for communication with such a cavity, closure means normally closing said chamber with respect to the cavity and constructed to open in response to predetermined pressure in said chamber, said die member having a passageway therein communicating with said chamber for the entry of a lubricant into said chamber, and said die member having another passageway therein communicating with said chamber for supplying a gas under pressure thereto, by means of which lubricant in said chamber may be discharged past the closure means into the cavity.

7. A die member according to claim 6, wherein said closure means comprises a valve member and resilient means biasing said valve member in a chamber-closing position with respect to said cavity, with said gas discharge being operable to apply pressure to said valve member in opposition to the action of said resilient means to effect an opening of said valve for the passage of lubricant therethrough.

8. A die member according to claim 7, wherein said die member is constructed to provide, in cooperation with such another die element, an overflow recess communicating with said cavity, with said chamber being disposed to open on said recess.

9. In a diecasting apparatus having a stationary platen and a movable platen constructed to receive and support die members cooperable to form a die cavity for receipt of molten metal, one of said die members having a passageway communicating with said cavity, means normally closing the cavity end of said passageway, a lubricant supply, means arranged to communicate with said supply and said passageway for controlling the supply of a predetermined amount of lubricant to said passageway, a gas supply under pressure, valve means having an inlet connected to said gas supply and an outlet connected to said passageway, means responsive to relative movement between said stationary and movable platens for actuating said lubricant controlling means to effect an injection of lubricant into said passageway as said die members approach a closed position, and means responsive to relative movement between said stationary and movable platens for controlling said gas valve means to effect discharge of gas under pressure into said passageway, following injection of lubricant therein, when said die members reach closed position, operative to open said closure means and substantially uniformly distribute lubricant throughout the die cavity.

10. An apparatus according to claim 9, wherein said die casting apparatus is of the open type having a shot sleeve communicating with the die cavity through which molten metal is supplied thereto, said sleeve opening to the atmosphere when said die members are in a closed position, prior to the receipt of molten metal into the die cavity, operative to provide a pressure release for gas discharged into said die cavity.

11. A diecasting apparatus according to claim 9, wherein said lubricant-controlling means comprises a pneumatically actuated metering device, and said actuating means therefor comprises an air valve operative to control the flow of actuating air to said metering device;

12. A diecasting apparatus according to claim 11, wherein said lubricant-controlling means includes cam means responsive to movement between the said platens, engageable with means for actuating said valve controlling airflow to said pneumatically actuated metering device.

13. A diecasting apparatus according to claim 12, wherein.

means biasing said valve member in a chamber-closing position with respect to said cavity, with said gas discharge being operable to apply pressure to said valve member in opposition to the action of said resilient means to effect an opening of said valve for the passage of lubricant therethrough.

Claims

11. A diecasting apparatus according to claim 9, wherein said lubricant-controlling means comprises a pneumatically actuated metering device, and said actuating means therefor comprises an air valve operative to control the flow of actuating air to said metering device.

13. A diecasting apparatus according to claim 12, wherein said gas valve means comprises a pneumatically operated pilot valve having a controlling timer, with said controlling means therefor comprising an electrically actuated air valve operative to control the flow of actuating air to said pilot valve.

14. A diecasting apparatus according to claim 13, wherein said gas valve controlling means includes switch means responsive to movement between said platens for actuating said electrically actuated air valve.

15. A diecasting apparatus according to claim 9, wherein said closure means comprises a valve member and resilient means biasing said valve member in a chamber-closing position with respect to said cavity, with said gas discharge being operable to apply pressure to said valve member in opposition to the action of said resilient means to effect an opening of said valve for the passage of lubricant therethrough.