EP0813922B1 - Vacuum die-casting machine and method - Google Patents

Vacuum die-casting machine and method Download PDF

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Publication number
EP0813922B1
EP0813922B1 EP97109129A EP97109129A EP0813922B1 EP 0813922 B1 EP0813922 B1 EP 0813922B1 EP 97109129 A EP97109129 A EP 97109129A EP 97109129 A EP97109129 A EP 97109129A EP 0813922 B1 EP0813922 B1 EP 0813922B1
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EP
European Patent Office
Prior art keywords
piston
die
fill chamber
bore
vacuum
Prior art date
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EP97109129A
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German (de)
English (en)
French (fr)
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EP0813922A1 (en
Inventor
James R. Fields
Men Glen Chu
Lawrence W. Cisko
Donald L. Drane
George C. Eckert
George C. Full
Thomas R. Hornack
Thomas J. Kasun
Marshall A. Klingensmith
Jerri F. Mcmichael
Richard A. Manzini
Janel M. Miller
A. Victor Pajerski
M.K. Premkumar
Robert E. Robinson
Thomas J. Rodjom
Gerald D. Scott
William G. Truckner
Robert C. Wallace
Mohammad A. Zaidi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Howmet Aerospace Inc
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Aluminum Company of America
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Priority claimed from US07/320,140 external-priority patent/US5076344A/en
Application filed by Aluminum Company of America filed Critical Aluminum Company of America
Publication of EP0813922A1 publication Critical patent/EP0813922A1/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D18/00—Pressure casting; Vacuum casting
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C21/00—Alloys based on aluminium
    • C22C21/02—Alloys based on aluminium with silicon as the next major constituent
    • C22C21/04—Modified aluminium-silicon alloys
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
    • B22D17/14—Machines with evacuated die cavity
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
    • B22D17/20—Accessories: Details
    • B22D17/2007—Methods or apparatus for cleaning or lubricating moulds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
    • B22D17/20—Accessories: Details
    • B22D17/2015—Means for forcing the molten metal into the die
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
    • B22D17/20—Accessories: Details
    • B22D17/30—Accessories for supplying molten metal, e.g. in rations
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
    • B22D17/20—Accessories: Details
    • B22D17/32—Controlling equipment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
    • B22D41/50—Pouring-nozzles
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B21/00—Obtaining aluminium
    • C22B21/06—Obtaining aluminium refining

Definitions

  • This invention relates to vacuum die-casting machine and method for casting processes, especially high-pressure die-casting processes.
  • the invention has particular application to that branch of the die-casting field where vacuum is used to facilitate the die-casting operation and/or enhance the product.
  • Morgenstern disclosed a vacuum die-casting machine in U.S. Patent No. 2,864,140.
  • a vacuum die-casting machine of design similar to that of the Morgenstern machine is described in U.S. Patent No. 4,476,911 (the Lossack et al. patent).
  • Full vacuum is maintained, while the mold is being filled, by vacuum channels on both sides of the piston face, and the melt flow rate is carefully controlled by a choke or a filter to prevent contamination of the melt by air and lubricant vapors.
  • Piston cooling is provided to prevent "streaks" of melt escaping into the piston's sleeve, and a heat-resistant sealing material is also used to prevent air from entering the fill chamber through the piston sleeve in the Lossack et al. patent.
  • U.S. Patent No. 4,583,579 of Miki et al. discloses the measuring of temperature and calculation of clearance for a plunger, sleeve and spool bush in a die casting machine, in order to control plunger retraction and determine the presence of abnormal operating conditions.
  • U.S. Patent No. 3,544,355 discloses a method and apparatus for lubricating a shot cylinder in a die casting machine.
  • Spray head means is adapted to be moved into position for spraying the lubricant directly into the interior of the shot cylinder.
  • a vacuum die-casting machine having a die section, a fill chamber having a bore communicating at a first end with said die section and with an inlet opening adjacent a second end of said fill chamber, a piston slidable in said bore between a retracted position beyond said inlet opening toward said second end and an extended position toward said first end, said piston having a piston rod extending out of the bore beyond the second end of the fill chamber and pressure control means creating a vacuum in the fill chamber bore in front of the piston with said piston in the retracted position to draw molten metal into the fill chamber bore through said inlet opening, said machine characterized by a piston rod seal engaging said piston rod, enclosure means extending from the second end of said fill chamber to said piston rod seal forming an air-tight enclosure behind said piston, and said pressure control means simultaneously applying a vacuum to said enclosure behind the piston when a vacuum is created in the fill chamber bore in front of the piston.
  • a method of operating a die casting machine in which a piston which charges molten metal into a die is retracted in a bore in a fill chamber beyond an inlet opening and a vacuum is applied to the fill chamber bore in front of the retracted piston to draw molten metal into the bore of the fill chamber through the inlet opening, said method characterized by applying a vacuum behind said piston during application of vacuum in front of the piston.
  • a die-casting process incorporating this invention involves the following consideration:
  • AlSi10Mg.1 alloy aluminum-silicon-magnesium casting alloy
  • Ti may be present, for instance in the range 0.05-0.10 percent.
  • B may also be present.
  • a reasonable limit for such other elements is that they not exceed a total of 0.25 percent.
  • Another choice of limits might be: Others each 0.05% max, others total 0.15% max.
  • the functions of the constituents of the alloy are as follows.
  • the silicon lends fluidity to the melt for facilitating the casting operation, as well as imparting strength to the casting.
  • the strontium provides a rounding of the silicon eutectic particles for enhancing ductility.
  • Magnesium provides hardening during aging based on Mg 2 Si precipitation.
  • Addition of iron suppresses soldering of the alloy to the iron-based mold and to iron-based conduits or containers on the way to the mold. Soldering leads to sticking of the cast part to the die surface, roughening of dies and of the walls of die casting machine fill chambers, to breakdown of sealing, to wear of the pistons of die-casting machines, and to surface roughening on the castings matching the surface roughening of the dies.
  • Soldering is particularly a problem in the casting of die castings, which have high gate velocities relative to other casting techniques.
  • Die-castings in general, have a metal velocity through the gate in the range 15 to 70 meters/sec (50 to 200 feet/sec).
  • High gate velocities may be necessary for a number of reasons. For instance, thin gates are of advantage and desired for mass-produced die castings, because it is then easy simply to break the gate material away from the casting during trimming.
  • thin gates (maximum thickness ⁇ about 2 millimeters) necessitate high metal flow velocities through them, and higher metal pressures and temperatures, particularly in the casting of complexly shaped parts, and these conditions have all been found to promote soldering.
  • Another reason for high gate velocities can be the need to get complete filling of a mold for making a thin-walled casting, e.g. castings containing walls of thickness ⁇ 5 mm.
  • the commonly used countermeasure against soldering is increased iron content, up to 1, or even 1.3, % iron.
  • the iron compositional range for compositions preferred for use is low compared to the usual iron level used for high-gate-velocity die castings.
  • it can have a deleterious effect on ductility of the alloy and on the ability of cast parts to withstand crush tests.
  • low-gate-velocity, thick-gate castings may be die-cast without too much worry of causing soldering. Of course, then the gates have to be sawed off, rather than broken off. Iron contents in the 0.3-0.4% range are used in low-gate-velocity die casting, and iron may even be as low as 0.15%.
  • iron-based dies are to be used, and especially in the case of high-gate-velocity die casting, it can be of advantage to add to the above composition certain elements which will alter the effect of the iron on mechanical properties.
  • an element may be added for affecting morphology of the plate-shaped iron-bearing particles from a platelet shape to a more spheroidized shape, in order to maintain ductility at higher Fe levels.
  • Elements which are considered as candidates for altering the effect of iron are Ni, Co, Be, B, Mn, and Cr at levels about in the range 0.05 to 0.1, 0.2, or even 0.25 percent.
  • compositions can be used.
  • iron may be varied in the range beginning at 0.5% downwards, and, in some instances, iron may be as, low as 0.2%, perhaps even down to 0.1%. Silicon may be decreased to around 8%. And, magnesium may be brought down to 0.10%.
  • an alternate, composition may be:
  • the present invention can as well be applied to the die-casting of the class of aluminum alloys containing 7-11% magnesium.
  • Alloy products which can be casted in varying embodiments are: 356, 357, 369.1, 409.2, and 413.2, as listed in the Registration Record of Aluminum Association Alloy Designations and Chemical Composition Limits for Aluminum Alloys in the Form of Castings and Ingots, published by the Aluminum Association, Washington, D.C..
  • Material (such as the AlSi10Mg.1 alloy described above) of the correct composition is melted, adjusted in composition as required, and then held for feed to a die-casting machine as needed.
  • Adjustment of composition comprises three parts: Removal of dissolved gas, addition of alloying agents, and removal of solid inclusions.
  • Modifying agent e.g. strontium, sodium, calcium or antimony
  • addition for modifying the shape of silicon phase may be added, for instance, in the form of master alloy wire of composition 3-4% Sr, balance essentially aluminum, to a trough where the melt is flowing from a melting furnace where melting and hydrogen removal was performed to a holding furnace where the melt is stored preparatory to casting.
  • chlorine reacts with Sr
  • bubble inert gas such as argon
  • Master alloy wire of composition 3.5% Sr, balance aluminum has been found to be more effective for this modification of the silicon in the eutectic than master alloy wire of composition 9% Sr, balance aluminum.
  • the residence time of a satisfactory silicon modification is greater than at 732°C (1350°F) than at 760°C (1400°F).
  • Strontium content is preferably in the range of about 0.01 to 0.03% in the molten metal and in the casting for effective silicon modification.
  • Solid inclusions not eliminated by skim removal in the melting ladle are removed by filtration, for example through ceramic foam or particulate filters. This may be carried out as the melt moves from the trough into the container in the holding furnace.
  • metal e.g. aluminum alloy
  • castings, particularly die castings it is advantageous to limit inclusions to for example, 12 ⁇ one 20- ⁇ m inclusion per cc of metal in the casting and, preferably ⁇ one 15- ⁇ m, or even ⁇ one 10- ⁇ m inclusion per cc of metal.
  • Filter pore and/or grit size is chosen to meet the chosen standard. The desired flow rate through the filter is then obtained by appropriate filter area and pressure head.
  • the inclusion content of the metal is determined by metallographic examination of a statistically adequate sample removed from the area of the holding furnace from which the metal brought into the die casting machine is taken.
  • the sample is obtained using equipment as described, for instance, by R. D. Blackburn et al. in papers presented at the Pacific Northwest Metals and Minerals Conference, April 27, 1979, and involves the sucking of a statistically adequate quantity of metal through a filter and analyzing the inclusions retained on the filter. In the 20- ⁇ m test for instance, the number of such inclusions found is divided by the quantity of metal sucked through the filter; the presence of inclusions of size greater than 20- ⁇ m means the metal fails the test.
  • Molten material is brought from the holding furnace to the die casting machine through a suction tube.
  • the suction tube preferably extends into a region of the holding furnace container where, as melts is removed for casting, melt pressure head causes melt replenishment to move through a filter into such region.
  • the suction tube extends from the holding furnace to a fill, or charging, chamber, also called a shot sleeve, at a hole in the fill chamber referred to as the inlet orifice.
  • the suction tube is preferably made of graphite (coated for protection against oxidation on its outer surface) or ceramic, for preventing iron contamination of the melt and for facilitating suction tube maintenance.
  • a ceramic, e.g. boron nitride, inlet orifice insert may be used to reduce heat transfer, thus guarding against metal freezing in the inlet orifice, and to reduce erosion at that location. This may be coupled with a ceramic insert in the shot sleeve in the area of the inlet orifice, also to prevent erosion. Erosion may be handled, as well, with an H-13-type steel replacement liner at such location.
  • An electric inlet orifice heater also may be used to guard against metal freezing at the inlet orifice. This so-called pancake heater operates in the manner described below.
  • a moat in the fill chamber outside wall, in the portion of the outside wall surrounding the inlet orifice, may also be used for reducing heat transfer out of the area of the inlet orifice.
  • a secondary, crushable, die-formed (by ribbon compression) graphite-fiber seal at the inlet orifice outside of primary seals may be used to guard against air leakage at the primary seals into the melt at the junction between the suction tube and the shot sleeve.
  • the fill chamber seats a piston, or ram, which is preferably made of beryllium copper.
  • the piston serves for driving melt from the fill chamber to the die, or mold.
  • means for applying coatings or lubricants are associated with this section of the die-casting machine to occupy the interfaces between the fill chamber and piston and between the fill chamber and the melt.
  • the piston one important aspect involves protection from its being a source of harmful gases, for instance air from the environment, leaking into the molten material contained under vacuum in the fill chamber.
  • the piston must be able to execute its different functions of first containing and then moving the melt to the die. It must be movable and yet sealed as much as possible against the encroachment of contamination into melt contained in the fill chamber, as noted in the Lossack et al. patent.
  • Advantageous features provided for the piston by the present invention include 1) aspects of sealing, 2) a joint between the piston and the piston rod, and 3) measures taken to control temperature so as to stabilize the sliding fit between the fill chamber bore and the piston exterior.
  • the seal extends between the fill chamber and the piston rod. This feature assures sealing for as long as desired during piston travel.
  • a flexible envelope between the fill chamber and the piston rod accommodates different alignments of the piston and rod. This arrangement also prevents damage to sealing gaskets by aluminum solder or flash which is generated by movement of the piston.
  • the piston includes a flexible skirt for fitting against variations in the bore of the fill chamber, in order to better seal the piston-fill chamber bore interface against gas leakage into melt in the fill chamber.
  • a swivel, or ball, joint, or articulation, between the piston and the piston rod may also be provided to allow the piston to follow the bore of the fill chamber.
  • the piston is cooled, this assisting, for instance, in freezing the so-called biscuit against which it rams in the final filling of the die.
  • Temperature is controlled, to resist contamination of the melt by gas leaking through the interface between piston and bore. Measures used include direct monitoring and controlling of piston temperature, which in turn permits control of cooling fluid flow to the piston based on timing or cooling fluid temperature.
  • the fill chamber itself may be made of H13 steel, which preferably has been given a nitride coating using the ion-nitriding technique.
  • the fill chamber may optionally have ceramic lining for providing decreased erosion, reduced release agent (lubricant) application or reduced heat loss.
  • ceramic lining for providing decreased erosion, reduced release agent (lubricant) application or reduced heat loss.
  • 2,671,936 of Sundwick can be provided in ceramic form, together with substitution of other parts of his molten metal supply equipment toward the goal of providing a hot chamber die caster resistant to attack by the metal being cast, particularly aluminum alloy.
  • Ceramic liners provide compositional choices not subject to the aluminum-iron interaction and can, therefore, stay smooth longer, this being of advantage, for instance, for preventing wear in the flexible skirt.
  • the fill chamber section additionally includes means for applying and maintaining vacuum.
  • Vacuum is achieved by adequate pumping and, even more importantly, it is maintained by attention to sufficient sealing. In general, it is poor practice to increase pumping and not give enough attention to the seals. Insufficient sealing will mean larger amounts of gas sweeping through the evacuated fill chamber and a concomitant risk of melt contamination.
  • Vacuum quality may be monitored by pressure readings (vacuum levels are kept at 40 to 60 mm Hg absolute, preferably less than 50 mm absolute, down to even less than 25 mm Hg absolute) and additionally by measures such as gas tracing, for instance argon and/or helium tracing, and gas mass flow-metering, under either feedback or operator control.
  • An important aspect of the fill chamber section involves the application of coatings or lubricants. Measures such as ion nitriding are done once and serve for making many castings. Other coatings and lubricants are applied often, for instance before the forming of each casting.
  • Coatings and lubricants may be applied manually, using nozzles fed by the opening of a valve. Or, they may be applied by use of so-called “rider tubes” which ride with the piston to lubricate the bore of the fill chamber. Rider tubes typically involve the use of a non-productive piston stroke between each die feeding stroke for lubricating the fill chamber bore preparatory for the next filling of melt into the fill chamber. Another option for lubrication is the "drop oiler” method, where oil is placed on the sides of the piston when it is exposed, for subsequent distribution to the bore of the fill chamber during piston stroke.
  • a fill chamber "die-end” lubricator is provided. It is called a “die-end” lubricator, because it accesses the fill chamber bore from the end of the fill chamber nearest the die, when the die halves are open.
  • the die-end lubricator eliminates the non-productive stroke.
  • Other important advantages of the die-end lubricator are uniform, thorough application of coatings and lubricants, the drying of the water and/or alcohol component of water and/or alcohol-based coatings and lubricants, and the sweeping, or evacuation, of solder, or flash, and evaporated water and/or alcohol from the fill chamber bore by pressurized gas blow.
  • the lubricants and coatings used in the fill chamber and die have been found to be especially advantageous for enabling high pressure die casting of parts in low iron, precipitation hardenable aluminum alloy.
  • the die castings have low gas content and can be heat treated to states of combined high yield strength and high crush resistance.
  • Both fill chamber bore and the cast-metal-receiving faces of the die are preferably given a nitride coating using the ion-nitriding technique.
  • Ion nitriding also known as plasma nitriding, is a commonly utilized surface treatment in die casting. Ion nitriding is used in conventional die casting mainly to reduce die wear caused by high velocity erosion.
  • This surface treatment of the fill chamber bore and the die preferably in combination with the use of lubricant, especially the halogen salt-containing lubricant has been found to be particularly effective for inhibiting soldering in the high pressure die casting of low iron, precipitation hardenable aluminum alloy.
  • Lubrication is important for long and successful runs which avoid soldering, i.e. attack of the steel fill chamber and die walls by aluminum alloy melt.
  • die and sleeve lubricants for the most part have very different functions, both lubricants have the common function that they must minimize the soldering salt reaction.
  • a halogenated salt of an alkali metal is added to die and fill chamber lubricants to achieve a marked reduction in soldering, particularly in the case of die-casting low-iron aluminum silicon alloys.
  • potassium iodide added to lubricant (2 to 7% in sleeve lubricant and 0.5 to 3% in die lubricant) inhibits the formation of solder buildup and enables a reduction in the lubricating species, for instance organic, required for performance.
  • the lubricating species in the water-based lubricants to which it is added emulsion, water soluble synthetic, dispersion or, suspension) only serve to provide the friction reduction required for part release on the die and heat transfer reduction in the sleeve.
  • lubricating species is polyethylene glycol at 1% in the water base.
  • Graphite is another lubricating species, which may be added to facilitate release of the castings from the die.
  • Lubricants containing halogenated salts of alkali metals provide an overall reduction in gas content in the cast parts.
  • die-end lubricator equipment to apply lubricant to the fill chamber bore.
  • Thee equipment enables the use of water and/or alcohol based lubricants for the bore.
  • the die-end lubricator has brought consistency to the lubricant application and provides the ability to apply inorganic materials, such as potassium iodide.
  • steam generated by the evaporation of the water is removed from the sleeve by the sweeping action of the drying air emitted from its nozzle.
  • the casting may be allowed to cool to room temperature and sand blasted, if desired, for removing surface-trapped lubricant, to reduce gas effects during subsequent treatment, for instance to reduce blistering during subsequent heat treatment and outgassing during welding.
  • the sand blasting can also remove surface microcracks on die casting this leafing to improved mechanical properties in the die castings, particularly improved crush resistance.
  • Heat treatment of die castings of the AlSi10Mg.1 aluminum alloy is designed to improve both ductility and strength.
  • Heat treatment comprises a solution heat treatment and an aging treatment.
  • Solution treatment is carried out in the range 482 to 510°C (900 to 950°F) for a time sufficient to provide a silicon coarsening giving the desired ductility and to provide magnesium phase dissolution.
  • the lower end of this range has been found to give desired results with much reduced tendency for blistering to occur. Blistering is a function of flow stress and the lower temperature treatment (which are associated with lower flow stress) therefore helps guard against blistering.
  • the lower end of the range also provides greater control over silicon coarsening, the coarsening rate being appreciably lower at the lower temperatures.
  • Aging, or precipitation hardening follows the solution heat treatment. Aging is carried out at temperatures lower than those used for solution and precipitates Mg 2 Si for strengthening.
  • the concept of the aging integrator as set forth in U.S. Patent No. 3,645,804, may be employed for determining appropriate combinations of times and temperatures for aging. Should the casting be later subjected to paint-bake elevated temperature treatments, the aging integrator may be applied to ascertain the effect of those treatments on the strength of the finished part.
  • This solution plus aging treatment has been found to permit the selection of combined high ductility and high strength, the ductility coming from the solution treatment, the strength coming from the aging treatment, such that a wide range of crush resistance, for instance in box-shaped castings, can be achieved.
  • solution heat treatment temperatures at the lower end of the solution heat treatment temperature range be used.
  • Time at solution heat treatment temperature has an effect.
  • the yield strength obtainable by aging decreases as time at solution heat treatment temperature increases.
  • Achievable yield strength falls more quickly with time at solution heat treatment temperature for the higher solution heat treatment temperatures, for instance 510°C (950°F), than is the case for lower solution heat treatment temperatures, for instance 493°C (920°F).
  • Achievable yield strength starts out higher in the case of solution heat treatment at 510°C (950°F) but falls below that achievable by solution heat treatment at 493°C (920°F) as time at solution heat treatment temperature increases.
  • Free bend test deformation is determined using a test setup as shown in Fig. 15.
  • the radii on the heads, against which the specimen deflects measure 1.27 cm (0.5 inch).
  • the specimen measuring 2 mm thick by 7.62 cm (3 inch) long by 1.52 cm (0.6 inch) wide, is given a slight bend, such that the specimen will buckle as shown when the loading heads are moved toward one another.
  • For specimens thicker than 2 mm they are milled, on one side only, down to 2 mm thickness, and bent such that the outside of the bend is on the unmilled side.
  • the top and bottom loading beads close at a constant controlled stroke rate of 50 mm/min. Recorded as "free bend test deformation” is the number of millimeters of head travel which has occurred when specimen cracking begins. Free bend test deformation is a measure of crush resistance.
  • Gas level is determined by metal fusion gas analysis of the total casting, including mass spectrographic analysis of the constituents. Typically, gas level is below 5 ml, standard temperature and pressure (STP), i.e. 1.033 Kg/cm 2 (1 atmosphere pressure) and 240°C (75°F), per 100g metal.
  • STP standard temperature and pressure
  • 1.033 Kg/cm 2 (1 atmosphere pressure) and 240°C (75°F) per 100g metal.
  • the practice of melting the total casting is to be contrasted with the possibility of testing individual portions cut from a casting. Melting the total casting provides a good measure of the real quality being attained by the casting equipment and process.
  • Weldability is determined by observation of weld pool bubbling, using an A, B, C scale; A is assigned for no visible gassing, B for a light amount of outgassing, a light sparkling effect, but still weldable, and C for large amounts of outgassing and explosions of hydrogen, making the casting non-weldable.
  • gas level is a measure of weldability, weldability being inversely proportional to gas level.
  • Corrosion resistance is determined by the EXCO test, ASTM Standard G34-72.
  • Fig. 1 shows a side view, partially in section, of a die-casting machines.
  • Fig. 2 shows a cast piece from the die in Fig. 1.
  • Fig. 3 is a schematic representation of melting practiced.
  • Fig. 4 is an elevational, cross-sectional, detail view of one embodiment of the region around the fill chamber end of the suction tube in Fig. 1.
  • Fig. 5 is an elevational, cross-sectional, detail view of a second embodiment of the region around the fill chamber end of the suction tube in Fig. 1.
  • Fig. 5A is schematic, perspective view of a third embodiment of the region around the fill chamber end of the suction tube in Fig. 1.
  • Fig. 6 is an elevational, cross-sectional, detail view of a seal for sealing the piston-fill chamber interface.
  • Figs. 6A and 6B are views as in Fig. 6 of modifications of the seal.
  • Fig. 7 is an axial cross section of a second embodiment of a piston.
  • Fig. 8 is an axial cross section of a third embodiment of a piston.
  • Fig. 9 is a cross sectional, plan, schematic view of the die-casting machine as seen using a horizontal cutting plane in Fig. 1 containing the axis of the fill chamber 10.
  • Fig. 10 is a view as in Fig. 9, showing more detail and a subsequent stage of operation.
  • Fig. 11 is a view based on cutting plane XI-XI of Fig. 10.
  • Fig. 12 is a view based on cutting plane XII-XII of Fig. 10.
  • Fig. 13 is a view based on cutting plane XIII-XIII of Fig. 10.
  • Fig. 14 is a view based on cutting plane XIV-XIV of Fig. 13.
  • Fig. 15 is an elevational view of the test setup for measuring free bend test deformation.
  • Fig. 16 is an oblique view of a casting.
  • Fig. 17A is a schematic, partially cross-sectioned, view of an internally cooled piston-in a heated fill chamber bore.
  • Figs. 17B to 17D are control diagrams.
  • FIG. 1 shows, in the context of a cold chamber, horizontal, self-loading, vacuum die casting machine, essentially only the region of the fixed-clamping plate 1, or platen, with the fixed die, or mold, half 2 and the movable clamping plate 3, or platen, with the movable die, or mold, half 5 of the die casting machine, together with the piston 4, suction tube 6 for molten metal supply, holding furnace 8, and fill chamber 10.
  • the vacuum line 11 for removing air and other gases in the direction of the arrow, is connected to the die in the area where the die is last filled by incoming molten metal.
  • Line 11 is opened and shut using valve 12, which may be operated via control line 13 by control equipment (not shown).
  • Fig. 2 shows an example of an untrimmed die-cast piece, for example in the form of a hat, with the gate region 14 separating the hat portion 15 from the sprue 16 and biscuit 17.
  • the vacuum connection appears as appendage 18.
  • gate region 14 is thin, e.g. ⁇ 2 mm thick, such that it can be broken away from the cast part. Also the vacuum appendage is sized for easy removal.
  • a conical, or spherical, projection 4a is provided at the frontal face of the piston 4.
  • the rear of the piston is connected to piston rod 21.
  • the rear region 10a of the fill chamber 10 shows a sealing device 90, which is explained in detail below in the discussion of Fig. 6.
  • the suction tube 6 is connected to the fill chamber 10 by means of a clamp 22.
  • This clamp 22 has a lower hook-shaped, forked tongue 24 which passes underneath an annular flange 25 on the suction tube 6. From the top, a screw 26 is threaded through the clamp 22. This enables a clamping of the end of suction tube 6 to the inlet orifice of the fill chamber 10.
  • Die end lubricator 170 is used to apply lubricant to the bore of fill chamber 10 from the die end of the fill chamber, when the movable die and platen, plus ejector die (not shown) have separated from the fixed die and platen. Reference may be had to Fig. 9 for added information concerning this lubricator.
  • Operation of the die casting machine of Fig. 1 generally involves a first two phases, and a subsequent, third phase can be included.
  • Phase 1 vacuum is applied to evacuate the die and fill chamber and to suck the metal needed for the casting from the holding furnace into the fill chamber.
  • Phase 1 further includes movement of the piston at a relatively slow speed for moving the molten charge toward the die cavity.
  • Phase 2 which is marked by a high velocity movement of the piston for injecting the molten metal into the die cavity, is initiated at, or somewhat before, the time when the metal reaches the gate where the metal enters into the cavity where the final part is formed.
  • Phase 3 involves increased piston pressure on the biscuit; piston movement has essentially stopped in Phase 3.
  • Fig. 3 illustrates an example of melting equipment used for providing a suitable supply of molten alloy, for instance AlSi10Mg.1, for die casting.
  • Solid metal is melted in melting furnace 40 and fluxed, for example using a 15 minute flow of argon + 3% by volume chlorine from the tanks 42 and 44, followed by a 15 minute flow of just argon.
  • a volume flow rate and gas distribution system suitable for the volume of molten metal is used.
  • metal is caused to flow from melting furnace 40 into trough 46, where strontium addition is effected from master alloy wire 48.
  • filter 50 may be provided in a separate unit within the holding furnace 8.
  • the filter pore sizes can be the same or different.
  • inlet filter 50 can be a coarse-pored ceramic foam filter and exit filter 54 a fine-pored particulate filter.
  • both filters can be fine-pored particulate filters.
  • the filter pore sizes are chosen to provide the above-specified metal quality with respect to inclusion content in the castings.
  • Filter 54 could be placed on the bottom of tube 6 and subcompartment 56 eliminated, but the structure as shown is advantageous in that it permits the use of a larger expanse of fine-pored filter 54 this making it easier to assure adequate supply of clean molten metal for casting.
  • Fig. 4 shows details of an embodiment of the inlet orifice 60 in fill chamber 10. Three important aspects of this embodiment are guarding against 1) metal freezing onto the walls of the inlet orifice, 2) erosion of the walls of the inlet orifice by the molten metal flow, and 3) loss of vacuum within the fill chamber.
  • a boron nitride insert 62 contributes particularly to aspects 1 and 2.
  • Primary seals 64 and 66 contribute particularly to aspect 3, sealing the inlet orifice at seating ring 68, nipple 70, and ceramic liner 72.
  • Heat is fed into nipple 70 by heating coil 71, for instance an electrically resistive or inductive heating coil.
  • Pancake heater 80 is formed of a grooved ring 82.
  • the groove carries an electrical resistance heating coil 84.
  • the heater is held against plane 86, which is a flat surface, machined on the exterior of exterior surface of the fill chamber.
  • Steel bands 88 encircle the fill chamber to bold the heater in place.
  • Flange 25 is provided, in order that clamp 22 of Fig. 1 may hold the end of the suction tube tightly sealed against the fill chamber 10.
  • Fig. 5 shows details of a second embodiment of the inlet orifice 60 in fill chamber 10.
  • This embodiment illustrates the use of an air-filled moat 76 surrounding the inlet orifice.
  • the moat 76 can be filled with an insulating material other than air. The moat mitigates the heat-sink action of the walls of the fill chamber, in order to counteract a tendency of melt to freeze and block the inlet orifice.
  • Fig. 5 also illustrates the idea of a ceramic, or replaceable steel liner 78 for the bore of the fill chamber.
  • Fig. 5A illustrates an embodiment caring for this concern of temperature maintenance in a unique way.
  • the suction tube 6 is relatively short, compared to its length in the embodiments of Figs. 4 and 5, and the reservoir 130 of molten metal is brought up near to the inlet orifice 60 such that heat transfer from the molten metal in the reservoir keeps the inlet orifice 60 clear of solidified metal.
  • the reservoir is provided in the form of a trough, through which molten metal circulates in a loop as indicated by the arrows. Pumping and heat makeup is effected at station 132.
  • All containers may be covered (not shown) and holes provided for access, for instance for suction tube 6.
  • Metal makeup for the loop comes from the coarse filter 50 of Fig. 3, and the fine filter 54, is provided as shown, in order to effect a continuous filtering, of the recirculating metal.
  • Fig. 6 illustrates several features, one feature in particular being an especially advantageous seal for sealing the piston-fill chamber interface against environmental air and dirt.
  • Fig. 6 there is shown piston 4 seated in fill chamber 10 at the fill chamber end farthest from the die. Inlet orifice 60 appears in the drawing. It will be evident that the piston as shown in Fig. 6 is in the same, retracted, or rear, position in which it sits in Fig. 1. Rather than, or in addition to, packing which might be provided at the interface between chamber 10 and piston 4, the embodiment of Fig. 6 provides a seal 90 extending between the fill chamber 10 and the piston rod 21.
  • seal 90 comprises several elements. First, there is a fill chamber connecting ring 92 bolted to the fill chamber. A gasket (not shown) occupies the interface between ring 92 and the fill chamber, for assuring gas tightness, despite any surface irregularities between the two.
  • envelope 94 is provided in the form of a bellows.
  • Ring 93 in turn is bolted, also with interposition of a gasket, to piston rod follower 96.
  • An air-tight packing 98 lies between follower 96 and rod 21.
  • seal 90 Also forming a part of seal 90 are a line 100 from envelope 94 to a source of vacuum, a line 102 to a source of argon, and associated valves 104, 106, controlled on lines, as shown, by programmable controller 108, to which are input on line 110 signals indicating the various states of the die casting machine.
  • Seal 90 operates as follows.
  • follower 96 rides on rod 21 as the piston executes its movement in the bore of fill chamber 10 to and from the die. Either from influences such as banana-like curvature of the bore of fill chamber 10 or due to flexing of the piston rod under the loading of its drive (not shown), and even as influenced by possible articulation of the piston to the piston rod (as provided in embodiments described below), there can be a tendency for the piston rod to want to rotate about axes perpendicular to it. Because of the flexible envelope, these rotational tendencies are easily permitted to occur without adverse effect on the sealing provided by packing 98.
  • the follower simply moves up and down in Fig. 6, or into or out of Fig. 6, to follow the piston rod in whatever way it might deviate from the axes of the piston and fill chamber bore.
  • controller 108 With respect to controller 108, it serves the following function. When the piston is in the retracted position as shown, controller 108 holds valve 104 open and valve 106 closed. Vacuum reigns both in the bore of the fill chamber and within envelope 94. The required amount of molten metal enters the bore through inlet orifice 60, whereupon piston rod 21 is driven to move piston 4 forwards toward the die. The supplying of molten metal is terminated as the piston moves into position to close the inlet orifice.
  • the programmable controller prevents this by using the information on machine state from line 110 to close valve 104 and open valve 106. Argon fills envelope 94 to remove the vacuum and prevent melt from being sucked through inlet orifice 60.
  • argon is an alternative gas which may be used in this way.
  • Helium sensors in the vacuum lines connected to the die and fill chamber and a knowledge of where helium has been introduced allow tracing and determination of the piston to fill chamber seal.
  • Metal fusion gas analysis utilizing mass spectrometer technology allows detection of argon in a casting, and, with acknowledge of where argon was present during the casting process, information can be gathered on the tightness of the intervening seals.
  • line 102 is replaced or augmented by one or more longitudinal slots 103 on the outer diameter of piston rod 21.
  • An alternative or supplement of the effect of slots may be achieved by a reduction in the diameter of the rod. Use of the reduction in diameter is advantageous as compared to the slot, because the edges of the slot can cut the packing, unless they are rounded off.
  • the slots or reduction are placed such that, just as piston 4 is about to clear inlet orifice 60, whereupon molten metal would be sucked into envelope 94, the slots open a bypass of the seal provided by packing 98.
  • the bypass provided by slots 103 opens to the air of the environment.
  • the slots 103 open to the interior of basically a duplicate 90A of the structural items 92, 93, 96, 90 containing argon essentially at atmospheric pressure on the basis of line 102 and valve 106. Pressures somewhat above atmospheric pressure may be used, for instance if argon replenishment through line 102, as the volume gets bigger due to the access provided by slots 103, is not rapid enough to otherwise maintain the necessary pressure to drop, and keep, the metal level below the inlet orifice 60.
  • the flexible envelope 94 of the duplicate and the length of slots 103 are sufficiently long that argon can feed into cylinder 10 right through to the stopping of the piston against the biscuit.
  • the duplicate of 92 is connected to the follower 96 of the structure of Fig. 6.
  • the envelope of this duplicate structure is also chosen sufficiently long that the slot 103 does not open the argon chamber (which it provides) to outside air when the piston is in its retracted position, i.e. in its position as shown in Fig. 6B.
  • Fig. 6 Other features of Fig. 6 include a supplementary seal 112 on follower 96.
  • the piston presses against seal 112 when the piston is in its retracted position.
  • Fig. 6 Also shown in Fig. 6 are the concentric supply and return lines 114, 116 for cooling fluid (for instance, water and ethylene glycol) to the piston.
  • Thermocouples (not shown) in the fill chamber walls, piston metal-contact and bore-contact walls (the leads of these thermocouples are threaded back through the cooling fluid lines), and in the water stream are used or open or closed loop stabilizing of the sliding, fit between fill chamber bore and piston.
  • Other factors such as force needed to move the piston (this being a measure of the friction between bore and piston), or the amount of argon appearing in the vacuum lines connected to die and fill chamber, may as well be used in monitoring and control schemes for stabilizing the sliding fit to minimize gas leakage through the interface between piston and bore.
  • FIG. 6 Another feature is illustrated in Fig. 6.
  • the back edge of the piston has been provided with a flash, or solder reaction product, remover 118.
  • This remover is made of a harder material which will retain the sharpness of its edge 120 better than the basic piston material which is selected on the basis of other design criteria, such as high heat conductivity.
  • remover 118 operates to scrape, or cut, loose flash or solder left during the forward, metal feeding stroke of the piston. Attention is given to keeping the forward edge 122 sharp too, but, as indicated, this is an easier task in the case of remover 118.
  • Fig. 7 shows a second embodiment of a piston.
  • This piston numbered 4' to indicate the intent that it serve as a replacement for piston 4, includes a flexible skirt 140 for fitting against variations in the bore of the fill chamber.
  • Skirt 140 is made, for instance, of the same material as the piston itself. It is flexible in that it is thin compared to the rest of the piston and it is long. Its thickness may be, for example 0.038 cm (0.015 inch) all of which stands out beyond the rest of the piston; i.e. outer diameter of the skirt is e.g. 0.076 cm (0.030 inch) greater than the outer diameter of the rest of the piston.
  • the skirt has an outer diameter about 0.0025 cm (0.001 inch) greater than the inner diameter of the bore of fill chamber 10, i.e., there is nominally a slight interference fit is the skirt with the bore. The flexibility of the skirt avoids any binding.
  • skirt 140 is relatively weak in compression.
  • the skirt In order that solder built up, or flash, not collapse the skirt on the rearwards stroke of the piston, the skirt includes a hem 142.
  • the inner diameter of hem 142 is less than that of a neighboring shelf 144 on the body of the piston. Should the skirt encounter any major resistance on the rearward piston stroke that would otherwise compressively load the skirt, the hem transfers such loading to the body of the piston and thus protects the skirt from any danger of collapse.
  • Threading at 146 and 148 is used for assembling the piston.
  • Holes 150 provide for use of a spanner wrench.
  • metal spinning techniques may be used to provide an outward bulging of the thin portion of skirt 140.
  • Metal spinning involves rotating the skirt at high speed about its cylindrical axis and bringing a forming tool, for instance a piece of hardwood, into contact with the interior of the thin portion of skirt 140, to expand the diameter outward. While this acts to increase the nominal interference with the fill chamber bore, the thinness of the material prevents binding of the piston in the bore This added bulging increases the sealing effect of the skirt.
  • Fig. 8 shows a third embodiment of a piston.
  • This piston 4" provides some features in addition to those shown for piston 4' in Fig. 7.
  • piston 4" includes a ball-, or swivel-, joint articulation 160 of the piston rod to the piston.
  • This includes a spherical-segment cap 162 welded in place along circular junction 164 to assure containment of cooling fluid.
  • hem and shelf facing surfaces in Fig. 8 are machined as conical surfaces in Fig. 8 for providing improved reception as the skirt deflects up to approximately 0.90° maximum rotation, as indicated at A in the drawing.
  • Assembly of piston 4" is carried out as follows.
  • the socket of the ball joint is supplied by piston face 266 and piston side wall 268, which are joined by threads 269.
  • Shim, or spacer, 270 controls, by its thickness, the amount by which the threads engage, in order to provide proper fit between the ball and the socket. Tightening of the threaded engagement is obtained by applying a clamp wrench to the outer diameter of face portion 266 and a spanner wrench to the slots 272 cut longitudinally into the rear of side wall 268.
  • Collar 274 is next threaded onto the tail 276 of the ball, using a spanner wrench in holes 278.
  • Thee ball is prevented from turning relative to the collar by insertion of the hexagonal handle of an Allen wrench inserted into its bore 280 also of hexagonal cross section.
  • Fig. 9 shows a general view of the die-end lubricator 170. It is attached to the fixed clamping plate 31 and can be rotated by hydraulic or pneumatic cylinder 172 into the operative position shown by the dot-dashed representation when the die halves have been opened. In the operative position, a head in the form of nozzle 174 is ready to be run into the fill chamber bore to execute its applicator, drying, and sweeping functions.
  • Fig. 10 shows the die-end lubricator in greater detail.
  • Programmable controller 108 has already received information from the die-casting machine via line 110 that the machine is in the appropriate state (i.e. the die halves are open and the last casting has been ejected) and has interacted with the fluid pressure unit 176 via line 178 to cause the hydraulic cylinder to move the lubricator into its operative position.
  • controller has subsequently instructed servo-motor 180 on line 182 to drive timing belt 184, thereby turning pulley 186 and the arm 188 rigidly connected to the pulley, in order that the nozzle 174 has moved into the bore of fill chamber 10.
  • Interconnection of nozzle 174 to arm 188 involves e.g. a length of flexible tubing 190 which carries four tubes 192, hereinafter referenced specifically 192a, 192b, 192c and 192d, which serve various purposes to be explained.
  • Nozzle 174 carries a polytetrafluoroethylene (PTFE) collar 194 to guide it in the bore of the fill chamber 10.
  • the collar has a generally polygonal cross section, for example the square cross section shown in Fig. 11, and it only contacts the bore at the polygonal corners, thus leaving gaps 196 for purposes which will become apparent from what follows.
  • Fig. 12 shows that the flexible conduit 190 is constrained to move in a circular path by channel 198 containing PTFE tracks 200, 201, 202, as it is driven by arm 188.
  • Fig. 12 also shows the four tubes which will now be specified.
  • Tubes 192a and b are feed and return lines for e.g. water-based lubricant or coating supply to nozzle 174.
  • Tube 192c is the nozzle air supply
  • tube 192d is a pneumatic power supply line for a valve 204 (Fig. 13) in nozzle 174.
  • the tubes 192 extend between nozzle 174, through the conduit 190, to their starting points at location 206 inwards toward the pivot point for arm 188.
  • flexible tubing (not shown) is connected onto the tubes 192, the flexible tubing extending to air and lubricant supply vessels (not shown).
  • Nozzle head 208 which is circular as viewed in the direction of arrow B, has a sufficient number of spray orifices 210 distributed around its circumference that it provides an essentially continuous conical sheet of backwardly directed spray.
  • An example for a nozzle head diameter of 5.71 cm (2.25 inch) is 18 evenly spaced orifices each having a bore diameter of 0.061 cm (0.024 inch).
  • Angle C is preferably about 40°. Angles from 30° to 50°, preferably in the range 35 to 45°.
  • the nozzle mixing chamber 212 receives e.g. water-based lubricant or coating from tube 214 and air from tube 216, or just air from tube 216, depending on whether valve 204 has opened or closed tube 214 as directed by pneumatic line 192d.
  • the nozzle 174 is joined to the flexible tubing at junction 218.
  • Line 192c goes straight through to tube 216.
  • Lines 192a and b are short-circuited at the junction, in order to provide for a continual recirculating of lubricant or coating, this being helpful for preventing settling of suspensions or emulsions.
  • the short-circuiting 220 is shown in Fig. 14.
  • Tube 214 is continually open to the short-circuit, but only draws from that point as directed by valve 204, at which time controller 108 causes a solenoid valve (not shown) ill the return line to close, in order to achieve maximum feed of lubricant or coating to the nozzle.
  • Programmable controller 108 of Fig. 10 interacts with the pneumatic pressure supply for line 192c to send air to open valve 204, such that a lubricant or coating aerosol is sprayed onto the bore of the fill chamber as the nozzle moves toward the die in the bore.
  • the controller does not operate the servo-motor to drive the nozzle so far that it would spray lubricant down the inlet orifice 60.
  • the nozzle is stopped short of that point, but sufficient aerosol is expressed in the region that part of the bore at the inlet orifice does get adequately coated.
  • the controller additionally provides the ability to vary nozzle speed along the bore, in order to give trouble points more coating should such be desired.
  • controller 108 then operates cylinder 172 to swing the lubricator back out of the way, the die halves are closed, and the die-casting machine is ready to make the next casting.
  • the gaps 196 allow space such that the gas flow out of the nozzle can escape at the die end of the fill chamber.
  • This invention departs from the work of Miki et al. described in the above-mentioned patent 4,563,579 ('579) by focussing on the fit between piston and fill chamber during the metal feed stroke of the piston as a source of gas in castings made in vacuum die casting machines.
  • the fit between the piston and bore during the feed stroke of the piston is controlled for resisting gas leakage through the piston-bore interface into the metal which is being forced while under vacuum by the piston into the die.
  • Different measures may be taken to achieve this control.
  • One measure is to regulate the cooling of the piston such that the temperature swing of the piston over the course of a casting cycle is lessened.
  • the cooling may be regulated to maintain the piston temperature such that a sliding, gas-leakage minimizing fit is achieved, rather than a looser, gas-admitting fit.
  • a second measure which may be used in conjunction with the first measure, includes providing ar interference or an otherwise close or sliding fit of she piston in the fill chamber bore at some reference temperature, for instance room temperature, aid heating the fill chamber to make the piston movable with tight fit in the fill chamber bore. With the fill chamber being heated, the piston temperature will swing less upward relative to the bore temperature and a tighter, gas-resisting fit can be maintained during the metal feed stroke.
  • some reference temperature for instance room temperature
  • Both measures can be adapted depending on the particular materials of construction, and thus, for instance, on the coefficients of thermal expansion characterizing the materials.
  • the underlying basis for adaptation is the concept of keeping the clearance between piston and fill chamber bore gas-tight during the feed stroke of the piston, balanced with requirements for the force needed to move the piston and control of wear of piston and fill chamber bore.
  • Figs. 17A to 17D illustrate control of the piston to fill chamber clearance.
  • Piston 4 is internally cooled or heated by water or other fluid entering through supply line 114 and return line 116. Provision is made for continual flow of water through a by-pass line 300 containing a manually operable valve 302 and a check-valve 304.
  • Controller 306 operates an on-off, or variable-position (for use in the case of proportional, proportional-integral, PID, etc., control), valve 308, based on its program and information received from thermocouple 310, whose leads may be threaded out of lines 114 or 116 to the controller.
  • a heater or cooler 312 is provided on the fill chamber 10 and controlled from the controller 306 using thermocouple 314.
  • Figs. 17B to 17D are examples of different control schemes which may be used for controlling piston temperature. In general, it is preferred to control the piston to fill chamber clearance by way of interactions with the piston, since it responds quicker than the fill chamber, due to its copper material and its smaller size.
  • the control may be a closed-loop control using piston temperature information from thermocouple 310. Illustrated is an on-off control with hysteresis. The operator selects the piston temperature set point Tsp, as well as the temperature deviations ⁇ 2 and ⁇ 1 which together sum to determine the differential gap.
  • a closed-loop control based on piston outlet water temperature is used, there thus being a set point for the water temperature. Piston outlet water temperature is the feedback signal.
  • Figs. 17c and 17d illustrate open-loop control with variable pulse widths ⁇ 1 and ⁇ 2 input by the operator.
  • the time point 320 is vacuum start or Phase 2 start, Phase 2 being the portion of the piston metal feed stroke where a higher piston travel speed is used, once the metal has reached, or is about to reach, the gate(s) into the portion of the mold cavity where the actual part will be formed.
  • the time point 322 is vacuum end.
  • a complex casting illustrating the invention had the configuration as shown in Fig. 16.
  • the hat casting is composed of a 100 mm section 330 of 5 mm wall thickness and a 200 mm section 332 of 2 mm wall thickness.
  • the casting has a height 334 and depth 336 both of 120 mm.
  • the main gate 342 measured 4 mm x 60 mm in cross section and the two lateral gates 344 each had cross sections of 2 mm x 10 mm.
  • the casting was produced as the 32nd casting of a 95 casting run in a vacuum die casting machine as shown in Fig.
  • Cycle time 0.0 minutes vacuum during Phase 1 of about 20 mm Hg abs., piston diameter of 70 mm, Phase 1 piston velocity of about 325 mm/sec, Phase 2 piston velocity of about 1785 mm/sec, Phase 3 metal pressure of 868 Dyne/cm 2 (12,580 psig (868 bar)), 141 ml of 1% KI lubricant on the die faces, 7.6 ml of 5% KI lubricant on the fill chamber bore, and metal temperature in holding furnace of 1310°F. Holding furnace metal analysis was 10.1% Si, 0.3% Fe, 0. 13% Mg, 0.03% Sr, 0.052% Ti.
  • the die casting machine included the bellows-seal of Fig.

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  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Molds, Cores, And Manufacturing Methods Thereof (AREA)
  • Casting Or Compression Moulding Of Plastics Or The Like (AREA)
  • Injection Moulding Of Plastics Or The Like (AREA)
  • Encapsulation Of And Coatings For Semiconductor Or Solid State Devices (AREA)
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EP97109129A 1989-03-07 1990-03-06 Vacuum die-casting machine and method Expired - Lifetime EP0813922B1 (en)

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US320140 1981-11-10
US07/320,140 US5076344A (en) 1989-03-07 1989-03-07 Die-casting process and equipment
EP90905277A EP0462218B1 (en) 1989-03-07 1990-03-06 Die-casting process and equipment

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Families Citing this family (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3921513B2 (ja) 2002-04-17 2007-05-30 株式会社木村工業 成型装置及びそれに用いる型ユニット
US6923935B1 (en) 2003-05-02 2005-08-02 Brunswick Corporation Hypoeutectic aluminum-silicon alloy having reduced microporosity
US7666353B2 (en) 2003-05-02 2010-02-23 Brunswick Corp Aluminum-silicon alloy having reduced microporosity
DE10327165B4 (de) * 2003-06-15 2008-08-07 Kern Gmbh Magnesium-Giesstechnik Vorrichtung zur Herstellung von Leichtmetallgusserzeugnissen
DE10330400A1 (de) * 2003-07-04 2005-01-20 Alutec-Belte Ag Verfahren und Vorrichtung zum Abschrecken eines Gussteils
DE102004024952B4 (de) * 2004-05-21 2008-06-05 Bayerische Motoren Werke Ag Druckgusswerkzeug
DE102007012424A1 (de) * 2007-03-15 2008-09-18 Bayerische Motoren Werke Aktiengesellschaft Verfahren zur Herstellung einer Aluminium-Legierung
DE102012025447B4 (de) * 2012-12-21 2016-11-03 Wieland Anlagentechnik Gmbh Druckgussvorrichtung, Schmiermittelversorgungssystem und Schmierverfahren
DE102013208151B4 (de) * 2013-05-03 2020-11-19 Breuckmann GmbH & Co. KG Verfahren zur Herstellung von Erzeugnissen aus Metall
JP6941729B2 (ja) 2018-04-12 2021-09-29 株式会社アーレスティ 鋳造装置、鋳物の製造方法およびシール構造
CN108543939B (zh) * 2018-05-24 2019-12-31 苏州市永利成模具制造有限公司 一种生产设备机械智能控制系统
CN111151728A (zh) * 2020-01-06 2020-05-15 广州市丹爵通讯科技有限公司 一种用于5g信号增强器的安全系数高的压铸设备
CN112589385A (zh) * 2020-11-26 2021-04-02 宁德特波电机有限公司 一种防止软性材质轴承室变形工艺
CN112974784B (zh) * 2021-02-20 2022-09-02 广东韶钢松山股份有限公司 一种钢包包盖存放装置及快速钢包加盖、揭盖的方法
CN115415502B (zh) * 2022-08-05 2024-03-08 苏州市艺达精工有限公司 一种多穴位压铸模具
DE102023100621A1 (de) * 2023-01-12 2024-07-18 Thomas Ninkel Vorrichtung zum Schmelze-Dosieren an einer Druckgießmaschine

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR918574A (fr) * 1945-08-21 1947-02-12 Procédé de purification des métaux et alliages
US2864140A (en) * 1955-10-31 1958-12-16 Package Machinery Co Vacuum die casting means
US3087808A (en) * 1960-07-28 1963-04-30 Chemetron Corp Process for cleaning and degassing molten aluminum and aluminum alloys
US4049248A (en) * 1971-07-16 1977-09-20 A/S Ardal Og Sunndal Verk Dynamic vacuum treatment
AT333452B (de) * 1973-10-31 1976-11-25 Elin Union Ag Einrichtung zum entgasen von metallschmelzen
DE2641116A1 (de) * 1976-09-13 1978-03-30 Walter Reis Vorrichtung zum druckgiessen von metallen, z.b. aluminium, unter evakuierung der druckgiessformen
US4534403A (en) * 1980-10-14 1985-08-13 Harvill John I Hot chamber die casting machine
DE3041340A1 (de) * 1980-11-03 1982-05-13 Maschinenfabrik Weingarten Ag, 7987 Weingarten Druckgiessverfahren zur herstellung von gasarmer, porenarmer und oxydarmer gussstuecke sowie druckgiessmaschine zur durchfuehrung des verfahrens
JPS5967350A (ja) * 1982-10-08 1984-04-17 Toshiba Corp アルミニウム材
NL8601158A (nl) * 1986-05-06 1987-12-01 Gijsbert Willem Meindert Van W Inrichting en werkwijze voor het zuiveren van een naast een of meer verontreinigingen in hoofdzaak een lichtmetaal, in het bijzonder aluminium, bevattende smelt.
US4738717A (en) * 1986-07-02 1988-04-19 Union Carbide Corporation Method for controlling the density of solidified aluminum

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DE69033755D1 (de) 2001-07-26
EP0813922A1 (en) 1997-12-29
EP0814171B1 (en) 2002-12-04
EP0814171A1 (en) 1997-12-29
KR100187514B1 (ko) 1999-04-01
KR920700809A (ko) 1992-08-10
DE69033755T2 (de) 2002-05-29
DE69034025D1 (de) 2003-01-16
DE69034025T2 (de) 2003-07-24
ES2125221T3 (es) 1999-03-01
DE69032853D1 (de) 1999-02-04
ATE202305T1 (de) 2001-07-15
ES2184006T3 (es) 2003-04-01
BR9007214A (pt) 1992-03-24
ES2158405T3 (es) 2001-09-01
ATE229090T1 (de) 2002-12-15
DE69032853T2 (de) 1999-07-22
ATE174828T1 (de) 1999-01-15

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