US3861457A

US3861457A - Regulating devices for pouring molten metal

Info

Publication number: US3861457A
Application number: US269074A
Authority: US
Inventors: Py Alphonse Bl
Original assignee: Renault SAS
Current assignee: Renault SAS; Regie Nationale des Usines Renault
Priority date: 1971-07-21
Filing date: 1972-07-05
Publication date: 1975-01-21
Anticipated expiration: 1992-01-21
Also published as: GB1399914A; DE2235674A1; DE2235674B2; FR2146148B1; FR2146148A1; IT963190B

Abstract

A regulator device for pouring foundry parts, especially parts poured in chill-moulds following the so-called low-pressure method, in which the metal is introduced into a mould by delivery from the melting furnace under the action of a gaseous pressure higher than atmospheric pressure, characterized by the fact that it comprises apparatus for controlling the operations of application of pressure to the furnace and of filling the mould as a function of the pressure of the furnace compared with a pilot reference pressure, this pilot pressure being in turn compared and identified automatically with an adjustable datum pressure, automatically compensated after each injection of molten metal into the mould and unaffected by the conditions of operation of the installation; a device actuated by these comparison values for controlling the supply of filling gas to the furnace with a large flow-rate and for the supply at a small flow-rate; mechanism for opening and shutting-off the flow-rates as a function of differential pressures regulated by the furnace pressure and the pilot pressure, permitting a predetermined programming of the flow-rates and pressures for filling the mould.

Description

United States Patent BI Py Jan. 21, 1975 REGULATING DEVICES FOR POURING MOLTEN METAL [75] Inventor: Alphonse Bl Py, Billancourt, France [57] ABSTRACT [73] Assignees: Kegie Nationale des Usin es Renault, A regulator device f pouring foundry parts espe Bmancouft (Hams de Selma); cially parts poured in chill-moulds following the so- Automoblles Peugeot Pans both called low-pressure method, in which the metal is in- France troduced into a mould by delivery from the melting 22 Filgd: J 5 1972 furnace under the action of a gaseous pressure higher than atmospheric pressure, characterized by the fact [21] Appl- 269,074 that it comprises apparatus for controlling the operations of application of pressure to the furnace and of [30] Foreign Application p i i Data gilling the moulddas ahfunc tlion off the pressure of tlhe urnace compare wit a p1 0t re erence pressure, t 15 July 21, 197l France 71.26657 pilot pressure being in turn Compared and identified [52] U S Cl 164/155 164/4 automatically with an adjustable datum pressure, auto- [51] B22; 39/00 matically compensated after each injection of molten [58] Field 155 285 metal into the mould and unaffected by the conditions of operation of the installation; a device actuated by hese comparison values for controlling the supply of [56] References Cited filling gas to the furnace with a large flow-rate and for UNITED STATES PATENTS the supply at a small flow-rate; mechanism for opening Sylvester and shutting-Off the flowq'ates as a function of differ- 3,385,473 5/1968 Forcesi 164/155 U ential pressures regulated by the furnace pressure and g tfl' the pilot pressure, permitting a predetermined pro- 36503l3 3H9. gg a 16 x gramming of the flow-rates and pressures for filling Primary Examiner-R. Spencer Annear the mould.

6 Claims, 1 Drawing Figure Attorney, Agent, or Firm-Stevens, Davis, Miller &

Mosher 30 szl ll REGULATING DEVICES FOR POURING MOLTEN METAL The present invention relates to a device for regulating the pouring of foundry parts, especially of parts poured into chill-moulds following the so-called lowpressure method, in which the metal is introduced into the mould by being expelled from its melting furnace under the action of a gas pressure higher than atmospheric pressure.

In the methods of pouring in chill-moulds, the quality of the parts is closely bound-up with the reproducibility of the operations and in particular of the chilling conditions of the moulds. In the low-pressure pouring method, the gradual fall in the level of metal in the furnace results in a variation of the volume located above this level and this results in a disadvantageous constant modification of the time of response at the injection upon each application of pressure to the furnace.

A method is known which provides for compensation for this increase of the volume of gas after each injection, by putting into reserve a corresponding quantity of compressed gas to compensate for this increase in volume at each fresh injection, with a view to ensuring a constant of the injection time. However, the natural elasticity of the gaseous medium, which varies with its change of volume, does not allow this method to reach a satisfactory level of accuracy as regards the reproducibility of the conditions of injection. Furthermore, in order to ensure the best conditions of filling for the moulds, it has proved necessary to vary the flow-rate of liquid metal in accordance with well-defined and reproducible conditions.

The device forming the object of the present invention enables these functions to be ensured.

This device is characterized by the fact that it comprises:

Control means for the operations of pressurization of the furnace as compared with a pilot reference pressure, this pilot pressure being in turn compared and identified automatically with an adjustable datum pressure, automatically compensated after each injection and insensitive to the conditions of operation of the installation;

means for controlling, from these comparison values, the supply of gas for filling the furnace with a high rate of flow and a supply with a small flow-rate;

means for opening and shutting-off these flow rates in dependence on the differential pressures regulated from the furnace pressure and pilot pressure, permitting a predetermined programming of the flow-rates and filling pressures of the mould.

The originality of the device resides in the use of the physical quantity measurement on which the process of filling of the mould depends, the pressure of the furnace as compared with a reference pressure, for tripping and the control of the supply means of gas under v pressure to the furnace. This measurement by comparipressure. The outer air sucked-in through the conduit 4 passes through a filter 5 and penetrates at a pressure of 3 to 6 bars into the conduits 6 to 11.

The datum pressure is given by the water column 13, the height of which is adjusted manually before the first injection, according to the pressure which should exist in the furnace after its charging and following a first injection of metal into the mould. The dry air coming from the conduit 7 passes through a diaphragm regulator 14 which, for safety reasons, reduces its pressure to 800 millibars. The flow-rate of the air is limited by its passage through the throttling device 15 which may advantageously be a SOLEX jet having a flow conversion ratio of 170/100. The air then passes into the conduit 16 which directs it into the leakage regulator 17 and then into the conduit 18 before passing into the space 3 of the furnace, where there is thus ensured a pilot pressure equal to the datum pressure.

The air passing out of the conduit 6 passes through a three-way electro-valve 20 and then through a conduit 21 before passing into a dosing pump 22, which is coupled to an air reservoir 23 at atmospheric pressure, known as an accumulator, through a conduit 24. This accumulator, into which oil is introduced as soon as the furnace is re-charged after the first injection, has the advantage of avoiding the use of water columns. On the other hand, it necessitates the use of very accurate pressure gauges. The output of the pump 22 is coupled to a separator 25, in which the oil and water are separated by decantation. The bottom of the separator from which the water is collected is in communication with the diaphragm regulator 17 through the conduit 26.

The values of the datum pressure are indicated by a pressure-gauge 28 which communicates by the conduit 29 with the bottom of a closed chamber 30 which is coupled at its upper portion on the one hand by the conduit 31 to the conduit 18 and on the other hand by the conduit 31' to the pressostat 32, the function of which is to shut-off the large delivery after injection of the metal into the mould.

In the same manner, the values of the pressure of the furnace can be read-off from the water column 33, which is connected to the chamber 36. This latter is connected at its upper portion to a conduit 37 which opens into the conduit 18. Apart from the pressostat 32, the conduit 31' and the conduit 18 are also coupled to the safety pressostat 33, to the pressostat 34 which closes the small flow-rates, and to the pressostat 35 which closes the large flow-rates.

The conduit 8 opens on the one hand into a pressurereducing valve 40, and on the other hand into a pressure-reducing valve 41, at the output of which the air pressure is reduced to 800 millibars. The pressurereducing valve comprises an outlet conduit 42 which opens into a regulator 45 through a conduit 44, and then into a conduit 46 and into a conduit 48. Two throttle devices 50 and 51, respectively of 200 mm. and 100 mm regularize the flow of the air in the conduit 42.

The conduit 9 passes through an electro-valve 52 with three ways and then through a two-way electrovalve 53 and finally through an adjustable throttle device 54, before the opening into the conduit 56 coming from the regulator 45, which is connected to the regulator 41 by the conduit 57.

The conduit 10 opens into a three-way electro-valve 60 which is connected by a conduit 61 to a two-way electro-valve 62. The conduit 56 opens into the electro-valve 62 after having passed through an adjustable throttle device 64. The conduit 46 opens on the one hand at 65 into the space 3 of the furnace and at 66 into the regulator 68 which is connected by the conduit 69 to the conduit 18.

Finally, the conduit 11 opens into the three-way electro-valve 70. This valve is connected by 71 to the twoway electro-valve 72 which is in communication by conduit 73 with

conduits

42 and 48.

The operation of the device comprises the following stages:

a. Arrival of the metal at the lower level of the mould: after closing the mould, the pressure of the furnace is increased by opening the valves 53 and 62, the flowrate of which is controlled by the throttle devices 54 and 64. As soon as the furnace pressure corresponds to the arrival of the metal at the lower level of the furnace, the pressostat 35 effects the closure of valve 53.

b. Filling of the mould: the slow rise of the metal in the mould is ensured by the adjustment of the valve 62 and the throttle device 64.

c. Completion of mould filling: three cases of regulation are possible, depending on the type of part which it is intended to mould:

l. The rise in pressure is continued slowly by regulation with the pressostat 34 adjusted to l millibar;

2. The rise in pressure is continued slowly by pneumatic regulation by means of the regulator 45;

3. The pressure is rapidly applied by again opening the valve 53, the closure of which will only be effected by the pressostat 32 when the difference in the recorded pressures reaches to 30 millibars.

It is desirable to close the large flow-rate at 54 before the furnace pressure is equal to the datum pressure, in order to take account of the increase in pressure due to the heating of the air by the furnace.

The regulation is then effected by the throttle device 64, the valve 62 and the pressostat 34, or by the regulator 35 and the valve 62.

lf it happens that the valves 53 and 62 close with a certain delay and that in consequence the pressure of the furnace approaches the datum pressure, the regulator 68 becomes the source of a corrective leakage.

The pressostat 33 ensures the closure of the valves 53 and 62 in the event of failure of a control apparatus.

The sequences of filling the mould, initiated by pressures given in accordance with given flow-rates, are perfectly reproducible and independent of the surrounding technical conditions, such as the level of metal in the furnace, the compensation of which is made before the initiation of the process and independently of this process.

After each injection, the pressure compensation is automatically effected according to the quantity of metal necessary for each pouring. To this end, the distributor 20 actuates the dosing pump 22 which sends a determined quantity of oil into the separator 25, which causes a corresponding rise in the height of the water level in the datum column 13 or, in the case of working on an accumulator. the pump 22 delivers in a similar manner into the accumulator 23, which varies the pressure in consequence, this variation of pressure then actuating the regulator 17 as in the case of regulation by the water column 13.

The device, utilizing conventional equipment of pneumatic logic, is practically foolproof and is perfectly suitable for operation in the unfavorable surrounding conditions of foundries.

In addition to its application to low-pressure pouring installations, the device may be utilized in gravity pouring installations which necessitate an adjustable and reproducible flow-rate, the pouring ladle being placed in a chamber under pressure with an evacuation plunger tube delivering into the pouring system of the mould. This technique is especially applicable to the casting of large parts in light alloys, in sand moulds. The accurate regulation of the flow-rates when pouring makes it possible to simplify the pouring systems for the parts.

What is claimed as new is:

1. A regulator device for pouring foundry parts, especially parts poured in chill-moulds following the socalled low-pressure method, in which the metal is intro duced into a mould by delivery from a melting furnace under the action of a gaseous pressure higher than atmospheric pressure, comprising: first means for controlling the application of pressure to the furnace including first means for comparing the pressure of the furnace with a pilot reference pressure in order to fill the mould, said first controlling means including first means for generating a pilot reference pressure and second means for generating a datum pressure, means for automatically adjusting said datum pressure, and second means for comparing and automatically identifying the pilot reference pressure with the adjustable datum pressure which is automatically adjusted after each injection of molten metal into the mould and unaffected by the conditions of operation of the device; second means, actuated by the comparison pressures, for controlling the supply of filling gas to the furnace with a large flow-rate and for the supply at a small flowrate; means responsive to said second controlling means for opening and shutting-off the flow-rates as a function of differential pressures regulated by the furnace pressure and the pilot pressure, thereby permitting a pre-determined programming of the flow-rates and pressures for filling the mould.

2. A device in accordance with claim 1, wherein the control of the supply of gas to the furnace is effected by means of pressostats.

3. A device in accordance with claim 1 wherein said means for automatically adjusting includes a column of water having an adjustable height, and further comprising means for reading said datum pressure including a pressure gauge, a closed chamber having a bottom por tion connected to said pressure gauge via a first conduit, and an upper portion connected via a second conduit to a third conduit carrying the pilot pressure, a pressostat, said upper portion being connected via a fourth conduit to said pressostat which closes large flow-rate after injection of the metal into the mold.

4. A device in accordance with claim 1 wherein said first means for generating includes a first diaphragm regulator and a throttle device connected to said first regulator, and said means for comparing said pilot reference and datum pressures includes a second leakage regulator.

5. A device in accordance with claim I further comprising means for reading said furnace pressure including a water column and a chamber having a bottom portion coupled to said water column and an upper pressure gauge via a first conduit. and an upper portion connected via a second conduit to a third conduit carrying the pilot pressure, a pressostat, said upper portion being connected via a fourth conduit to said pressostat which closes large flow-rate after injection ofthe metal into the mold.

l= i i UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION e PATENT NO. 3,351 457 DATED January 1975 INVIENTOR(S) Alphonse Bl Py It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

The spelling of the assignee is incorrect in the heading of the Patent. The assignment section should read:

Regie Nationals des Usines Renault Billancourt, FRANCE Automobiles Peugeot 9 Paris, FRANCE slgned nd Scaled this [SEAL] D of March 1976 Attest:

q I RUTH c. MASON c. MARSHALL DANN Attestr'n 0 8 ff nmmrssmner /Parenrs and Trademarks

Claims

1. A regulator device for pouring foundry parts, especially parts poured in chill-moulds following the so-called low-pressure method, in which the metal is introduced into a mould by delivery from a melting furnace under the action of a gaseous pressure higher than atmospheric pressure, comprising: first means for controlling the application of pressure to the furnace including first means for comparing the pressure of the furnace with a pilot reference pressure in order to fill the mould, said first controlling means including first means for generating a pilot reference pressure and second means for generating a datum pressure, means for automatically adjusting said datum pressure, and second means for comparing and automatically identifying the pilot reference pressure with the adjustable datum pressure which is automatically adjusted after each injection of molten metal into the mould and unaffected by the conditions of operation of the device; second means, actuated by the comparison pressures, for controlling the supply of filling gas to the furnace with a large flow-rate and for the supply at a small flow-rate; means responsive to said second controlling means for opening and shutting-off the flow-rates as a function of differential pressures regulated by the furnace pressure and the pilot pressure, thereby permitting a pre-determined programming of the flow-rates and pressures for filling the mould.

3. A device in accordance with claim 1 wherein said means for automatically adjusting includes a column of water having an adjustable height, and further comprising means for reading said datum pressure including a pressure gauge, a closed chamber having a bottom portion connected to said pressure gauge via a first conduit, and an upper portion connected via a second conduit to a third conduit carrying the pilot pressure, a pressostat, said upper portion being connected via a fourth conduit to said pressostat which closes large flow-rate after injection of the metal into the mold.

5. A device in accordance with claim 1 further comprising means for reading said furnace pressure including a water column and a chamber having a bottom portion coupled to said water column and an upper portion connected via a conduit to a piping carrying the pilot pressure.

6. A device in accordance with claim 1 wherein said means for automatically adjusting includes an accumulator, and further comprising means for reading said datum pressure including a pressure gauge, a closed chamber having a bottom portion connected to said pressure gauge via a first conduit, and an upper portion connected via a second conduit to a third conduit carrying the pilot pressure, a pressostat, said upper portion being connected via a fourth conduit to said pressostat which closes large flow-rate after injection of the metal into the mold.