US2728110A - Method of controlling high speed die casting production - Google Patents

Description

Dec. 27, 1955 L. H. MORIN 2,728,110

METHOD OF CONTROLLING HIGH SPEED DIE CASTING PRODUCTION Filed Sept. 14, 1950 6/0 04 Hap IN VEN TOR.

Lows H. MOPIN Hi8 HT'T'OQNEYS United States Patent METHOD OF CQNTROLLING HIGH SPEED DEE CASTING PRQDUCTEQN Louis H. Morin, Bronx, N. 3. Application September 14, 1950, Serial No. 184,900 8 Claims. (Cl. 18-55) This invention relates to the art of forming die castings wherein casting material is pressure-injected into the cavity or cavities of a pair of relatively movable dies to form the castings. More particularly, the invention relates to the formation of die castings at a high rate of speed, and among the principal objects of the invention, it is proposed to increase the production rate of castings from a given machine, to produce castings substantially continuously from such machine at the increased rate, and to produce sound castings of good quality.

Heretofore in making die castings, and particularly in making separable fastener stringers by die casting fastener elements or scoops along the beaded edge of a stringer tape, it has been possible to produce such castings at a high rate of speed. The actual production rates have, of course, depended upon the size and/or Weight of the castings, as will hereinafter be described, but for a casting of a given size, it has been found 'thabthe production rate has an upper limit, above which itv has heretofore not been possible tooperate. Whenever attempts have been made to operate above these limits, a phenomenon known as hanging occurs, by which is meant the fact that the castings stick or adhere to a die. When hanging is encountered, the production speed must be slowed down, for if it is not, the gates or runnersbreak and the machine jams. Needless to say, the castings formed during hanging are not sound. Thus, in orderto produce castings at a continuous rate, it has inthe past been necessary to limit the speed of operationito a point where there is no adherence of thecastingsto the dies. This practice will for convenience be designated here as the prior practice, and will be so referred tohereinafter.

According to the present invention, it has been found that the production capacity can be considerably increased from a given machine while at the same time hanging can be eliminated by skipping the injection of casting'material intermittently just prior to the point where hanging would occur if the injection were :not skipped. In other words, the injections are performed'at such a rate that, I

if continued, the castings would adhere to a dieinstead of discharging cleanly therefrom, and this adherence or hanging is prevented by skipping injections intermittently, as stated .above. The injection of casting material is skipped at any one time only long enough to prevent hanging and it will be apparent thatthe preferred operation is to stop the injection for asshort an interval as possible in order not to limit production unnecessarily. .In a continuously operating method or machine, the injection of casting material is skipped at selected intervals. The selection of these intervals will depend upon the size and/or weight of the castings formed, and in anyparticular case may be determined empirically. That is to say,.the machine'or apparatus for producing the castings may be set in operation and pushed to a speed at which hanging occurs. With this speeddetermind, it will then be a relatively simple task to select the proper interval at which to regularly skip the injection of casting material'..

When these skipping intervals have been determined in a given case, the machine can then be operated continuously on this schedule. As will be understood, and as Will be described in more detail, the skipping of injections of casting material into the die cavity can be effected without interrupting the operation of the entire casting machine. In other words, the machine does not have to be shut down to skip an injection as injections may be skipped and resumed at a speed corresponding to the schedule established for the machine. After an injection has been skipped, the subsequent injections .will be effective to produce castings as were the preceding injections, and they will continue until the next injectionskipping interval has arrived.

It will be apparent that the invention provides a method of making die castings at a substantially greater production rate than in the prior practice described above and without encountering hanging. The reasons for this improved result, other than those described, are not entirely known.

As indicated, the invention is adapted to be practiced with high speed die casting machines. The kind of machine suitable for using the invention is illustrated in such patents as Nos. 2,497,010 and 2,367,303. Other pertinent patents in this connection are Nos. 2,446,056, 2,467,047 and 2,495,592. These patents relate both to machines for die casting separable fastener stringers and to machines for making castings not associated with a stringer tape or other mounting member. Inthese prior art machines, the dies are periodically opened and closed in suitable ways. For exampl they maybe moved by mechanical. means comprising'levers actuated by cams, as in Patent No. 2,486,053, or they may be operated pneumatically, as in PatentNo. 2,497,010. The machines are provided with goosenecks which inject molten-casting material into the die cavities at the proper time. That is to say, the dies are alternately'closed to receive an injection through a sprue channel and then opened to discharge the formed casting.- The injections are suit-ably made by teams of a-plungeror piston in the gooseneck which forces the casting material throughthe gooseneck nozzle. These machines all may be operated continuously, that is 'to'say, they-have a main drive shaft which may be in continuous operation andwhich may serve to drive the cam shafts or the pneumatic or othermeansfor opening and closing the'dies. Where separable fastener stringers are being formed, the machines are equipped to move the stringer tape, in intermittent fashion relatively to the dies and casting material is periodically injected into the die cavities to form cast scoops or elments along the edge of the stringer tape. The tape with the castings thereon is moved out of the-die cavities whi'e the dies are opened, and of course when the dies are closed the tape is station-' ary. This movement of the tape may be described as an intermittent one, with the actual movement taking place when the dies are opened.

In the accompanying drawing,.Fig. 1 is a diagrammatic sectional view of--a pneumatically operated valve and the control therefor; and

Fig. 2 is a diagrammatic-view illustrating, with legends, a method of producing one product.

Accordingto the -invention,-thepressure injection of casting material to the dies of the above prior art machines may be stopped-in any suitable way. For example, where pneumatic-means are employed to inject casting material through the gooseneck nozzle, an arrangement similar to-that shown in Patent No. 2,224,977 may be employed, whereby the supply of air to the pneumatically operated gooseneck plunger or piston is cut ofl? to stop the injection. One or more injections may thus be skipped while the machine continues to operate,

, by which is meant the factthatthe dies continue to open in Patent No. 2,497,010.

In the accompanying drawing is shown an illustrative valve arrangement for use on a pneumatically operated machine for making stringers, such as the machine disclosed in Patent No. 2,497,010, just mentioned. The purpose of this valve arrangement is to interrupt the flow of air to the gooseneck and to the means for moving the tape. In the drawing is shown a sprocket 1 which is geared by means not shown to the cam shaft 2 of the machine. The sprocket is adapted to move a distance equal to one tooth for each revolution of the machine. A control chain 3, composed of links 4, is arranged on the sprocket for movement in the direction of arrow 6. The chain is provided with lugs 5, which in the illustration shown are spaced ten links apart. As will be understood, lugs 5 are distributed throughout the length of the chain with each lug being spaced from adjacent lugs by ten chain links. The lug 5 at the upper end of the chain is shown in engagement with a roller 7 which is attached to the arm 8 of a lever 9 which is pivoted at 10. The other arm 11 of the lever operates in a recess 12 of a slide 13, the latter being mounted in the casing 14. As shown, the slide is in a depressed position, being maintained in such position by the lever 9 against the action of a spring 15. Casing 14 is provided with an upper pair of alined ports 16 for which an inlet pipe 17 and an exit pipe 18 are provided. Below the ports 16 in the casing is a pair of alined ports 19 having an inlet pipe 20 and exit pipe 21. Slide 13 is formed with ports 22 and 23, and when the slide is in its normal, nondepressed position, port 22 connects the ports 16 and port 23 connects ports 19.

If the foregoing valve arrangement is installed in a machine such as that shown in Patent No. 2,497,010, then sprocket 1 and chain 3 would be mounted on shaft 41 of the patent. When so mounted, chain .3 will turn at the same speed as chain 43. The flow of air through pipes 17 and 20 of the present valve arrangement will be controlled after it has been subjected to the control of the valve arrangement shown in the patent.

The operation ofthe present valve may be described br efly. It is assumed that every tenth injection will be skipped. Let it be assumed further that the casting machine of the patent is in operation; that is, the goose neck, the opening and closing movements of the dies, and the tape grip and feed mechanism are all operating or proceeding according to the patent. When lug 5 encounters the roller 7, as shown, lever 9 will be lifted and in turn will depress slide 13, and thus the flow of air through ports 16 and 19 will be interrupted. It will be understood that air flowing to pipe 20 comes from the pipe 141 shown in Fig. 1a of the patent. Normally, that is if slide 13 did not block the way, this air would exit through pipe 21, to the gooseneck, and actuate the latter. Air entering pipe 17 comes from ports 62, 63 shown in Fig. 1 of the patent and normally would exit through pipe 18' to actuate the tape grip and feed mechanism, as by entering port 112 shown in Fig. 2 of the patent. With the slide 13 in the position shown, however, no air will flow to the gooseneck or to the tape grip and feed mechanism, and therefore no injection of casting material and no movement of the tape will take place. After lug 5 has passed beneath roller 7, slide 13 will move upwardly under the influence of spring 15 until ports 22 and 23 are alined with ports 16 and 19, respectively. Air will then flow to the gooseneck and to the tape grip scoops per minute.

4 and feed mechanism, and the machine will operate according to the patent. Such operation will proceed for ten machine cycles, at which time a succeeding lug will actuate the valve mechanism and another injection and tape feeding movement will be interrupted.

it will be understood that chain 3 may be replaced by other chains in which the lugs 5 may be spaced apart by a number of chain links other than ten. It will also be understood that other castings may be made not attached to a tape or other mounting member, and that in this case the slide 13 and casing 14 will not be provided with ports 22 and 16 respectively, and that pipes 17 and 18 will not be necessary.

In Fig. 2 of the drawing the invention is diagrammatically illustrated by the production of a separable fastener stringer and, in this showing, 24 represents a series of nine successive shots producing nine successive scoops spaced along a separable fastener stringer 25 and, at 26, there is shown the skip or hold shot or station, wherein the tape 25 is held at rest while one casting shot is skipped. After the hold shot, the machine proceeds to produce successive shots and another series of successive castings, as at 24. At the station 26, another shot is skipped While the tape 25 is held at rest. Then the foregoing operation is repeated and this continues throughout the production of the separable fastener stringer. In the same way, successive groups of castings, rather than single castings, may be produced. That is to say, in Fig. 2 the numerals 24, 24' may represent successive shots in which a group of castings is formed per shot, as hereinafter described.

As has been indicated above, the prior practice has concerned production speeds of a relatively high order, depending upon the size and/or weight of the castings produced. For example, in the case of separable fastener stringers, the prior practice has produced an average of 1880 No. 5 scoops per minute and about 2000 No. 3 The scoops have been cast in groups which extend a distance of one inch along the tape edge, measured longitudinally. In a one inch group of No. 5 scoops, there are about 12 scoops, and the group weighs about 0.01344 ounce, while a one inch group of No. 3 scoops weighs about one half as much and contains 16 scoops.

It is possible by means of the invention to increase the production rates of these scoops above the rates noted. As an example showing the increased production rate, let it be assumed that stringers are to be made having No. 5 scoops. As described, a group of about 12 of such scoops may be cast by means of one injection or casting shot, and these scoops extend for a distance of one inch longitudinally of the edge of the tape. Each subsequent injection will add an inch of scoops to the tape. Let it also be assumed that in each cycle of operation of the machine, the injection or casting period is /3 of the total cycle. A cycle may be defined as extending from the beginning of one injection to the beginning of the next subsequent injection. The remaining portion of the cycle is consumed by such steps as the withdrawal of the casting nozzle from the dies, the opening of the dies, the movement of the tape relatively to the dies to discharge the casting and to bring a fresh portion of tape into the die cavities, the closing of the dies, and the movement of the nozzle back into die casting position. In the prior practice, the machine might operate at such a speed as to complete, say, 8 cycles in a given time, during which time 8 injections or casting shots would be made, 8 inches of stringer would be produced, and a total of 8X 12 or 96 scoops would be formed. By the present method, the machine speed may be so increased that over the same period of time the machine may complete 10 cycles, during one of which the injection of casting material is skipped. Thus 9 injection shots would be made to produce 9 inches of stringer and a total of 9x12 or 108 scoops. It may thus be seen pgvaamo that .in the sameamount of time as employed-tin the prior practice, the present method can'produce .9.in ch'es of stringer instead of 8, or an increase in production of 12.5%. 1

In the above example, one injection was skipped for every cycles of operation. This is, of course, .an illustrative figure, and it may be found, depending upon the size and/or weight of the casting, themachine, and possibly other factors, that operation can continue for 20, 30, 50 or 100 or more cycles before it is necessary to skip an injection. As indicated .above, the point .at which an injection is to be skipped will be determined empirically, anditis that point just .prior to the adherence of a casting to a die. Such adherence is evidenced by the fact that the castings do not discharge cleanly and sharply from the dies, and it is a visible effect. In this connection, the use in the claims of expressions like skipping an injection at selected intervals, or .at predetermined intervals refers to the fact that the injection is skipped just prior to the time that adherence of the casting to a die would result if the injection were not skipped.

It is to be understood that the invention is applicable to the production of various kinds of castings which may or may not be attached to a mounting member or tape. In regard to the production of separable fastener stringers, the invention is applicable for making relatively long lengths of stringers. Single castings, or groups of castings connected by a gate, may be formed, either of which may or may not be attached to a mounting. The weight of the castings, or groups of castings, that may be produced by the invention, is variable. Some idea of the lighter weights is given above. Castings weighing onefourth and one-half ounce may be conveniently produced, and castings weighing one ounce and more may also be made. Any suitable casting material may be used which is capable of being rapidly pressure-injected into die cavities at the speeds above described.

In the light of the foregoing description, the following is claimed:

1. In a method of operating a high speed die casting machine, wherein die castings are formed by a series of successive casting shots into a pair of dies in a continuous uninterrupted run of the machine, and wherein the casting is done at such a high rate of successive injection shots that adhesion of the castings to a die would occur if the shots were uninterrupted during said run, the improvement which comprises skipping a casting shot in accordance with a predetermined schedule throughout said complete uninterrupted run of the machine to thereby prevent such adhesion and to maintain high speed operation of the machine.

2. In a continuous high speed method of making die castings by pressure injecting casting material into the cavity of a pair of relatively movable dies that are alternately closed to receive an injection through a sprue channel and then opened to discharge the formed casting, and wherein a series of castings are formed by a series of successive injection shots in a continuous uninterrupted run of said shots, the improvement which comprises injecting the casting material at a rate of successive injection shots that produces castings which adhere to a die instead of discharging cleanly therefrom, preventing the castings from adhering to a die by skipping an injection shot of casting material at selected intervals during said complete run, and producing castings at a rate greater than would be possible if no injection shots were skipped.

3. In a continuous high speed method of forming separable fastener stringers wherein scoops are cast on a stringer tape by periodically pressure injecting casting material into the cavity of a pair of relatively movable dies through which the tape is intermittently moved, said dies being alternately closed to receive an injection and then opened to discharge the formed casting, and wherein said scoops are formed on the tape in a continuous uninterrnpted of injection shots; the improvement which comprises injecting the casting material at azrate of successive injection shots that would produce scoops which adhere to a die instead of discharging cleanly therefrom if the shots were uninterrupted, preventing the scoops from adhering to a die by skipping aninjection shot at selectedintervals during "said-run, and-coincidently with the skipping of an injection shot stopping the movement ofthe tape throughsaid cavity while continuing to open and close the dies, thereby increasing the production rate of 'said stringers. I

4. In a method-of operating at high speed a die:casting machine for forming separable fastenerrstringers, wherein scoops are formed alongan edge :of a stringer tape by a series of successive casting shots into a :single pair of relatively movable dies-through which-thetape is intermittently moved in a continuous uninterruptedrun of the machine, and whereinthe casting is done-at such a high rate of successive injection shots that adhesion of the scoops to a die would occur if the shots were uninterrupted, the improvement which comprises skipping a casting shot at predetermined intervals throughout a complete uninterrupted run of the machine to thereby prevent said adhesion and to maintain high speed operation of the machine, and moving the dies by opening and closing the same during the skipped shots.

5. The herein described method of producing a series of castings on an elongated mounting member by machine at a high rate of speed in a continuous uninterrupted run of the machine, which consists in completing a predetermined number of casting shots into a single pair of opening and closing dies to form castings longitudinally of said member while intermittently feeding said member between the dies when opened, making said casting shots at a high rate of speed such that adherence of a casting to a die would occur if the shots were uninterrupted, preventing said adherence by skipping a casting shot during said run while coincidently maintaining the mounting member at rest and at the same time opening and closing the dies, then completing another predetermined number of successive casting shots of the machine at said high rate of speed, again skipping a casting shot during said run to prevent said adherence while coincidently maintaining the mounting member at rest and opening and closing the dies, and repeating these operations in accord with a predetermined schedule throughout said run of the machine.

6. In the operation of a machine for forming separable fastener stringers by die-casting scoops along an edge of a stringer tape in a continuous uninterrupted run of injections, the improvement which comprises forming a successive series of cast scoops on the tape by intermittently pressure injecting casting material into a single pair of relatively movable dies and intermittently feeding the tape with respect to said dies to space the scoops thereon, injecting said casting material at such a high rate of speed as to produce scoops which adhere to a die if the injections were uninterrupted, periodically skipping the pressure injection of casting material into the dies during said run to prevent adherence of the scoops to a die, and coincidently with said last step retaining the tape against movement while continuing to open and close the dies.

7. In a continuous method of making die castings in an uninterrupted operation of a casting machine, which operation includes periodically pressure injecting casting material into the cavity of a single pair of relatively movable dies which are periodically closed to receive each injection through a sprue channel and then opened to discharge the formed casting, and wherein a series of castings are formed by a series of successive injection shots in a continuous uninterrupted run of the machine, the improvement which comprises injecting the heated casting material at a high rate of successive injection shots that would cause the castings to adhere to a die instead of discharging cleanly therefrom, skipping an injection shot of said casting material prior to adherence of the castings to a die, continuing to skip injection shots at selected intervals throughout said continuous uninterrupted run of the machine, opening and closing the dies during each skipped shot, and thereby preventing-the castings from adhering to a die and substantially increasing the production of castings by maintaining said high rate of injection shots interrupted only by the skipped shot intervals.

8. In a continuous high speed method of torrning castings on a mounting member by periodically pressure injecting casting material into the cavity of a pair of relatively movable dies through which the mounting member is intermittently moved, wherein a series of castings are formed by a series of successive injections in a continuous uninterrupted run of said injections, the improvement which comprises injecting the casing material at a rate that produces castings which adhere to a die instead of discharging cleanly therefrom, skipping an injection of casting material immediately prior to the occurrence of adherence of said castings to a die to prevent said adherence, repeating the skipping of injections at selected intervals throughout the course of said run to prevent said adherence, moving the dies by opening and closing the same during said skipped injections, continuously injecting casting material at said rate, except for said skipped injections, and continuously producing said castings on the mounting member at a high speed.

References Cited in the file of this patent UNITED STATES PATENTS 2,368,260 Morin Jan. 30, 1945 2,486,053 Morin Oct. 25, 1949 2,497,010 Morin Feb. 7, 1950

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