US3844331A - Method of regulating the pressure in low-pressure casting plants - Google Patents

Method of regulating the pressure in low-pressure casting plants Download PDF

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Publication number
US3844331A
US3844331A US00368341A US36834173A US3844331A US 3844331 A US3844331 A US 3844331A US 00368341 A US00368341 A US 00368341A US 36834173 A US36834173 A US 36834173A US 3844331 A US3844331 A US 3844331A
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United States
Prior art keywords
pressure
furnace
mould
gas
inputs
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US00368341A
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English (en)
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J Pichouron
A Benjamin
J Lefebvre
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Renault SAS
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Renault SAS
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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
    • B22D18/08—Controlling, supervising, e.g. for safety reasons

Definitions

  • ABSTRACT Method of regulating the pressure in a low-pressure casting plant wherein in a first step the furnace is supplied with two gas inputs, one of these two inputs being discontinued when the metal engages a first control means, the pressure in said furnace being memorized when the metal engages a second control means, and in a second step gas is supplied to the furnace until the mould is properly filled, whereafter the previously memorized pressure is utilized for supplying both gas inputs to the furnace; in a third step the memorized pressure is utilized for discontinuing one of the two inputs and regulating the pressure in said furnace during the setting of the metal in the mold.
  • the present invention relates to a method of controlling or regulating the pressure in a low-pressure casting plant comprising a heated furnace containing molten metal and a gaseous space overlying said molten metal, a mould disposed externally and above said furnace, a dipper pipe connecting the bottom of said furnace to the bottom of said mould (bottom casting), first control means inserted between said furnace and said mould bottom, second control means located in the mould bottom, and third control means disposed in the upper portion of said mould, said control means being adapted to regulate the supply of gas to said gaseous space.
  • a pressure control method consisting in compensating the increment in the gaseous volume contained in the furnace after each injection of molten metal into the mould is already known. To this end, a reserve of gas is provided for compensating or making up this increment in the gaseous volume at each run of the casting plant, in order to keep the injection time at a substantially constant value.
  • FIG. 1, divided into two fragmentary FIGS. 1A and 1B are to be read from left to right, respectively, illustrates the wiring and flow diagram of the plant operating according to the method of this invention, the two FIGS. 1A and 18 being readable together by aligning same at the reference letters a to h; and
  • FIG. 2 is a diagram plotting the time (in abscissa) vs. the gas pressure p (in coordinates) in the gaseous space in the furnace during a run.
  • a furnace or crucible 1 containing molten metal 2 has a gaseous space 3 overlying said metal and containing a gas under pressure.
  • This furnace l is heated in order to keep the metal 2 in the molten or liquid state.
  • a mould 37 disposed at a higher level than said furnace 1 has its bottom connected via a plunger or dipper pipe 38 to the bottom of said furnace.
  • the pipe 38 encloses an electric switch 52 constituting a first control device, and the lower portion or bottom of the mould 37 encloses another electric switch 53 constituting a second control device; a third electric switch 54 constituting a third control device is enclosed in the uppermost portion of the mould.
  • Each one of these three electric switches is adapted to close a separate electric circuit, as will be explained presently.
  • Gas under pressure is supplied from a source 4 (upper left-hand corner of FIG. 1A) via a feed line to the system. More particularly, pressure gas is supplied from this line 60 to the gaseous space 3 of furnace 1 (previous filtration in a suitable filter 5 in which the gas is both purified and dried) through a pressureregulator 21 and a pair of valves 18 and 18a.
  • the gas pressure in feed line 60 is in the range of 3 to 6 bars.
  • the gaseous space 3 is thus pressurized through feed line 60, filter 5, regulator 21 and the pair of solenoidoperated valves 18 and 18a, and adapted to be vented to the atmosphere by means of a valve 16 responsive to another solenoid-operated valve 11.
  • the feed line 60 comprises branch lines 7, 8, 9, l0 supplying gas to three-way solenoid-operated valves l2, l3, l4 and a pressure reducing device 15.
  • Valves l2 and 13 supply gas to a pair of three-way distributors l7 and 17a, respectively, controlling in turn, in a manner to be described presently, a pair of output-control valves 18 and 18a permitting the passage of a relatively large output (valve 18) and a relatively small output q (valve 18a) of gas to point 40 of feed line 60 leading to said space 3.
  • Another solenoid-operated valve 14 controls a passage valve 33 and the outlet 41 of pressure reducing device 15 is connected to a conduit 32.
  • a first pressure exchange device 25 consists of a vessel containing a liquid overlying which is a gas communicating with said conduit 42, a first liquid column 28 communicates with the liquid in the first exchanger 25, thus displaying at any time the pressure existing in the gaseous space 3; a second pressure exchanger 27 is constituted like the first one 25, and a second liquid column similar to the first column 28 is provided.
  • the passage valve 33 shown in its closed condition opens at the beginning of a cycle of operations and then interconnects the second column 30 (of which the height corresponds in this case to the pressure in space 3) and the second exchanger 27.
  • the passage valve 33 is subsequently closed, the second column 30 being thus isolated, and its height will remain constant. This constant height will be utilized in the manner to be set forth hereinafter as a reference or rated pressure in the subsequent operations of the cycle.
  • a pressure comparator 31 encloses a first chamber 44 communicating with the second column 30 and thus in this first chamber 44 the above-mentioned reference or rated pressure will prevail; said pressure comparator 41 also includes another chamber 46 supplied with gas through a throttled passage 57 from a conduit 32.
  • the pressure comparator 31 equalizes the pressure in its two chambers 44 and 46, so that from the time in a cycle of operations when the second column 30 displays the reference or rated pressure this same pressure also prevails in the second chamber 46 and in the conduit 43 connected thereto.
  • the pressure prevailing in conduit 43 is utilized in a manner to be explained presently for controlling certain operations of the cycle and thus constitutes the monitoring pressure.
  • a third pressure exchanger 26 is similar to the first and second pressure exchangers 25 and 27, and a third liquid column 29 corresponding to the third exchanger 26 is similar to the first and second liquid columns 28 and 30.
  • the gaseous atmosphere in the third exchanger 26 is connected to a conduit 43 whereby the third column 29 will show at any time the monitoring pressure constantly remaining substantially equal to the reference or rated pressure.
  • Two distributors 19a and 19 responsive to pneumatic differential control means are mounted in the manner illustrated between the pair of conduits 42 and 43; these distributors are adjusted for measuring the discrepancy existing between the monitoring pressure and the furnace pressure, and to deliver a control signal to regulator 21 and valves 18 and 18a through distributors 17a and 17 which can be closed when an electric signal is fed to the solenoid-operated valves 12 and 13.
  • the distributors l9 and 19a are set differently to afford a certain off-set between the closing of the large-output Q and the closing of the small output q.
  • the first differential switch 34 is adapted to cancel the pressures issuing from distributors 17 and 17a in case the reference or rated pressure were overstepped.
  • the other differential switch 35 is adapted to cut off the large-output flow Q when an electric pulse is supplied to its winding.
  • the differential switch 36 is adapted to cut off the small-output flow q when an electric pulse is supplied to its winding.
  • the pressure reducing device 21 is monitored through conduit 20a by the output of 19 which may be discontinued by actuating the valve 17.
  • This device 21 supplies gas to a line 22 divided into two branch lines 23 and 23a leading to the valves 18 and 18a, respectively, under the control of throttle valves 24 and 24a, respectively.
  • Electric lines shown diagrammatically at 47, 48 and 49 permit of actuating the solenoid-operated valves 13 and 14 from switches 52, 53, 54 in a manner to be disclosed presently.
  • the gaseous space 3 of furnace l is initially at the atmospheric pressure. This is shown at point A of the diagram of FIG. 2.
  • valve 11 cuts off the communication between conduit 6 and the atmosphere through the discharge valve 16.
  • Valve 14 opens the passage valve 33.
  • the pressure in space 3 is transmitted via conduit 42, exchanger 27 and valve 33 delivering at 43 a monitoring pressure equal to the pressure in space 3, thus permittingthe pressure recording phase.
  • the pair of solenoid-operated valves 13 and 21 are provided for monitoring the pair of distributors 17a and 17, respectively.
  • the other distributors 18a and 18 are monitored by distributors 19a and 19, respectively through valves 17a and 17, respectively, permitting the passage of outputs Q and q, respectively, for supplying gas to the space 3.
  • the pressure increases rather rapidly in this space 3 and drives the molten metal 2 which rises in pipe 38 and thus actuates the first switch 52. This is illustrated by section AB of the curve of HO. 2, whereby the metal rises at a relatively high rate in said pipe 38.
  • switch 52 cuts off the energization of solenoid-operated valve 13, thus discontinuing the monitoring of distributor 17a, and no gaseous flow is permitted through valve 18a, so that the large output 0 is eliminated.
  • the third switch 54 actuates the solenoid-operated valve 13 through another connection 48, thus restoring the large output Q through valve 18a and the sequence of steps explained in the foregoing, whereby the pressure rises again at a high rate in the furnace and in conduit 42.
  • This is illustrated by the curve starting at point D.
  • the distributor 19a assumes a different position in that it cuts off the flow of gas towards distributor 17a, whereby the latter will cut off the gas flow through valve 18a, and said large output Q is discontinued.
  • This condition corresponds to point E in the curve of FIG. 2, of which section DE has been followed. During this section DE an overpressure is applied to the metal body contained in the mould.
  • Valve 12 turns off the small output and valve 11 relieves the furnace pressure by venting same to the atmosphere through valve 16, and this corresponds to section GH of the curve of FIG. 2.
  • the liquid metal contained in pipe 38 then flows back into the furnace, and the final point I of the curve corresponds to the stripping or removal of the casting from the mould.
  • a method of regulating the pressure in a lowpressure casting plant comprising a heated furnace containing molten metal solid at room temperature and a gaseous space overlying the molten metal, a mould disposed externally and above said furnace, a dipper pipe connecting the furnace bottom to the mould bottom, first control means located between said furnace and the mould bottom, second control means disposed in the bottom of said mould, and third control means disposed in the upper portion of said mould, the furnace is supplied in a first step with two separate gas inputs, one of these two inputs being discontinued when the metal engages said first control means while memorizing the pressure in said furnace when the metal engages said second control means; in a secondstep gas is supplied to said furnace until the mould is properly filled, the memorized pressure being then utilized for delivering the two gas inputs to the furnace, and in a third step the memorized pressure is utilized for discontinuing at least one of said two inputs and regulating the pressure in the furnace during the solidification of the metal in said mould.
  • one of the two gas inputs which is discontinued is greater than the other, non-discontinued input.
  • said two gas inputs are monitored from a source of gas under pressure.
  • the memorized pressure is converted into a pressure for controlling and monitoring safety distributors.
  • the gas outputs are responsive to the discrepancy existing between the gaseous pressure in the furnace and the memorized pressure.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Casting Support Devices, Ladles, And Melt Control Thereby (AREA)
  • Control Of Fluid Pressure (AREA)
US00368341A 1972-06-22 1973-06-08 Method of regulating the pressure in low-pressure casting plants Expired - Lifetime US3844331A (en)

Applications Claiming Priority (1)

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FR7222546A FR2189150A1 (es) 1972-06-22 1972-06-22

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US (1) US3844331A (es)
JP (1) JPS5125206B2 (es)
CA (1) CA978326A (es)
DK (1) DK139660B (es)
FR (1) FR2189150A1 (es)
GB (1) GB1425868A (es)
IT (1) IT992577B (es)
SU (1) SU498897A3 (es)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3951199A (en) * 1973-08-02 1976-04-20 Soag Machinery Limited Method and apparatus for low pressure die casting
US4047558A (en) * 1974-06-28 1977-09-13 Honsel Werke Aktiengesellschaft Metering device for metal casting machines, particularly low pressure casting machines
US4585050A (en) * 1981-01-05 1986-04-29 Etude Et Developpement En Metallurgie, E.D.E.M., S.A.R.L. Process for automatic regulation of a casting cycle
US4860820A (en) * 1983-07-27 1989-08-29 A. W. Plume Limited Method and apparatus for the low-pressure die-casting of metals
US5178203A (en) * 1992-06-11 1993-01-12 Cmi International, Inc. Apparatus for the countergravity casting of metals
US5215141A (en) * 1992-06-11 1993-06-01 Cmi International, Inc. Apparatus and method for controlling the countergravity casting of molten metal into molds
WO2000001503A1 (en) * 1998-07-06 2000-01-13 Georg Fischer Disa A/S Method and apparatus for counter-gravity casting of metal
US6779588B1 (en) * 2001-10-29 2004-08-24 Hayes Lemmerz International, Inc. Method for filling a mold

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2460170A1 (fr) * 1979-07-04 1981-01-23 Etude Dev Metallurg Procede et dispositif d'automatisation d'un cycle de coulee sur machine basse-pression
DE3170075D1 (en) * 1981-01-05 1985-05-30 Edem Etude Dev & Metallurg Process and means for the automation of a low pressure casting cycle
JPS57130756A (en) * 1981-02-05 1982-08-13 Echiyuudo E Dev An Metarurujii Method of automatically controlling casting cycle

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2847739A (en) * 1951-07-12 1958-08-19 Griffin Wheel Co Casting apparatus
US3302254A (en) * 1962-10-04 1967-02-07 Ishikawajima Harima Heavy Ind Apparatus that automatically controls the correlation between time and airpressure
US3425483A (en) * 1966-05-13 1969-02-04 Amsted Ind Inc Means for controlling casting
US3768542A (en) * 1970-06-24 1973-10-30 British Steel Corp Level control in continuous casting

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2847739A (en) * 1951-07-12 1958-08-19 Griffin Wheel Co Casting apparatus
US3302254A (en) * 1962-10-04 1967-02-07 Ishikawajima Harima Heavy Ind Apparatus that automatically controls the correlation between time and airpressure
US3425483A (en) * 1966-05-13 1969-02-04 Amsted Ind Inc Means for controlling casting
US3768542A (en) * 1970-06-24 1973-10-30 British Steel Corp Level control in continuous casting

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3951199A (en) * 1973-08-02 1976-04-20 Soag Machinery Limited Method and apparatus for low pressure die casting
US4047558A (en) * 1974-06-28 1977-09-13 Honsel Werke Aktiengesellschaft Metering device for metal casting machines, particularly low pressure casting machines
US4585050A (en) * 1981-01-05 1986-04-29 Etude Et Developpement En Metallurgie, E.D.E.M., S.A.R.L. Process for automatic regulation of a casting cycle
US4860820A (en) * 1983-07-27 1989-08-29 A. W. Plume Limited Method and apparatus for the low-pressure die-casting of metals
US5178203A (en) * 1992-06-11 1993-01-12 Cmi International, Inc. Apparatus for the countergravity casting of metals
US5215141A (en) * 1992-06-11 1993-06-01 Cmi International, Inc. Apparatus and method for controlling the countergravity casting of molten metal into molds
WO2000001503A1 (en) * 1998-07-06 2000-01-13 Georg Fischer Disa A/S Method and apparatus for counter-gravity casting of metal
US6467532B1 (en) * 1998-07-06 2002-10-22 Georg Fischer Disa A/S Method and apparatus for counter-gravity casting of metal
US6779588B1 (en) * 2001-10-29 2004-08-24 Hayes Lemmerz International, Inc. Method for filling a mold

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DK139660B (da) 1979-03-26
JPS5125206B2 (es) 1976-07-29
JPS4955525A (es) 1974-05-29
DE2331956A1 (de) 1974-01-10
GB1425868A (en) 1976-02-18
DK139660C (es) 1979-09-17
FR2189150A1 (es) 1974-01-25
CA978326A (en) 1975-11-25
SU498897A3 (ru) 1976-01-05
DE2331956B2 (de) 1975-07-24
IT992577B (it) 1975-09-30

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