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WO1996018869A1 - Systeme de mesure de niveau pour bains de metal liquide - Google Patents

Systeme de mesure de niveau pour bains de metal liquide

Info

Publication number
WO1996018869A1
WO1996018869A1 PCT/NO1994/000202 NO9400202W WO9618869A1 WO 1996018869 A1 WO1996018869 A1 WO 1996018869A1 NO 9400202 W NO9400202 W NO 9400202W WO 9618869 A1 WO9618869 A1 WO 9618869A1
Authority
WO
WIPO (PCT)
Prior art keywords
level
bar
metal
smelting bath
bath
Prior art date
Application number
PCT/NO1994/000202
Other languages
English (en)
Inventor
Dag Baekkedal
Original Assignee
Dag Baekkedal
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Dag Baekkedal filed Critical Dag Baekkedal
Priority to PCT/NO1994/000202 priority Critical patent/WO1996018869A1/fr
Priority to AU13928/95A priority patent/AU1392895A/en
Publication of WO1996018869A1 publication Critical patent/WO1996018869A1/fr

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D2/00—Arrangement of indicating or measuring devices, e.g. for temperature or viscosity of the fused mass
    • B22D2/003—Arrangement of indicating or measuring devices, e.g. for temperature or viscosity of the fused mass for the level of the molten metal
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D21/00—Arrangement of monitoring devices; Arrangement of safety devices
    • F27D21/0028—Devices for monitoring the level of the melt
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
    • G01F23/24—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid
    • G01F23/241—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid for discrete levels
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
    • G01F23/24—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid
    • G01F23/241—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid for discrete levels
    • G01F23/242—Mounting arrangements for electrodes
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
    • G01F23/24—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid
    • G01F23/241—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid for discrete levels
    • G01F23/243—Schematic arrangements of probes combined with measuring circuits
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D9/00—Level control, e.g. controlling quantity of material stored in vessel
    • G05D9/12—Level control, e.g. controlling quantity of material stored in vessel characterised by the use of electric means

Definitions

  • the present invention concerns a level measurement system for measuring the metal level in a liquid metal bath, for use within the foundry industry, e.g. in magnesium casting.
  • Modern mass production of metal objects is normally performed by means of pressure die-casting, wherein a casting mould is filled with molten metal by means of a displacement pump.
  • This displacement pump is filled by means of gravity from a liquid, heated metal bath in a furnace, which requires a certain even static pressure which is maintained by ensuring that the level in the metal bath is at a certain constant height above the inlet of the pump.
  • New metal is added to the liquid metal bath in the form of bars which are placed in the bath manually, by means of feed tongs or a robot.
  • the supply of metal bars is often controlled manually by an operator who determines the supply rate on the basis of a measurement of the metal level in the molten mass and information on the withdrawal rate.
  • the measurement of the metal level is often performed manually, either by means of a measuring rod which is held down to the surface of the molten mass, or by the operator's assessment of the level. This naturally leads to some variation in the level.
  • the result of this is that the method of feeding in bars manually has been shown in practice to be unsatisfactory.
  • measuring methods are required in order to ascertain the level of the molten mass.
  • Various methods are employed for measuring the level of the molten mass.
  • One known method consists in the use of a float which by means of a mechanism or suspension arms supplies information to a scale instrument or a switch.
  • This type of measuring equipment is extremely vulnerable to incrustation, and consequently requires frequent maintenance. During maintenance the float has to be removed from the furnace, which means that the slag comes into contact with the oxygen in the air and is ignited. Consequently this type of measuring equipment is not desirable from the safety point of view or with regard to the working environment.
  • a second method which is used for measuring the level in a molten mass consists in the use of one or more stationary or movable electrodes, wherein an electrical circuit is closed and emits a signal when the electrode comes into contact with the molten mass.
  • US 4 728 875 describes such a method wherein two electrodes are mounted on an arm which is lowered into a smelting bath. The electrodes are mounted at a certain vertical distance in relation to each other, thus indicating the highest and the lowest level in the smelting bath. The arm is adjusted in such a manner that one electrode is in contact with the bath and one is located above the bath. If the level drops causing both electrodes to be out of the smelting bath, impulses are supplied for replenishing of metal. Should the level rise causing both the electrodes to come into contact with the smelting bath, the filling process is reduced or closed down completely.
  • a third measurement method is measuring by means of infrared radiation from the molten mass, wherein the measuring equipment is in the form of a disc-like container located under the lid of the smelting furnace. From the technical point of view this measurement method works satisfactorily, and is used to some extent. However, since there is usually very little space between the molten mass and the lid of the molten mass, typical 10 cm, it is necessary to take this measuring equipment apart during cleaning. The frequency of this cleaning will vary, but with round-the-clock operation it may generally involve between 3 and 9 cleaning operations every 24 hours, depending on the amount of pollution and incrustation. This measurement method is therefore extremely cumbersome to use.
  • Another measurement method which is in use is measuring by means of a laser.
  • This method functions per se without any special problems, but due to its complexity it is expensive to instal, and like any method which is based on electronics and/or precision mechanics in the vicinity of a smelting bath, it is sensitive to the influence of high temperatures and possibly spatter from the molten mass.
  • Measuring by means of laser normally requires a relatively large equipment, and is therefore better suited within the smelting plant industry, where the furnaces are larger than in the foundry industry.
  • a further measurement method which should be mentioned is measuring by means of radioactive isotopes which emit either gamma or particle radiation.
  • the radioactive source is located at one side of the liquid level which has to be measured, above the level of the liquid, and a measuring probe is located at the opposite side. During operation the liquid will absorb some of the radiation, depending on the level of the liquid. The intensity of the radioactive radiation is recorded by the measuring probe, which then passes a signal on to a calculation unit which calculates the level of the liquid.
  • This is a "universal method" which can be used within a number of technical fields, including the foundry industry, since it will work independently of high temperature, surface tension, incrustation and other features which are characteristic of a molten metal mass.
  • the object of the present invention is to provide a simple and reliable measurement method for measuring the level in a molten metal mass, which will have a reasonable cost both in installation and operation.
  • a measurement method will thereby be provided wherein the level measurement with associated feeding in of metal bars has sufficient accuracy to provide a level in the molten mass which is sufficiently constant to give an even static pressure which is suitable for mass production of die-castings with uniform quality.
  • the measuring principle is based on lowering an electrode into a smelting bath.
  • an electrode a metal bar is used which supplies raw metal to the smelting bath.
  • There must be a voltage potential between the bar and the smelting bath which means that the bar's lowering mechanism must be connected to a voltage source via a wire, but in other respects be electrically insulated from the smelting bath.
  • the electrode makes contact when it touches the smelting bath, thus causing a relay to be connected.
  • a metal bar can be lowered into the metal bath in various known ways, e.g. by the use of a hydraulically operated arm with a claw or tongs.
  • a robot may also be employed.
  • the invention is not dependent on the design of the lowering mechanism as long as the bar is electrically insulated from the smelting bath.
  • the measurement of the position of the lowering mechanism in relation to a fixed reference point is not subject to the above-mentioned problems which arise during the measurement of the level of the molten metal mass, and can therefore be performed in a number of known ways.
  • level switches can be mounted on the hydraulic cylinder, these switches being located in such a manner that they indicate the highest and the lowest smelting bath level.
  • the invention is not dependent on how the measurement of the level of the lowering mechanism is performed in relation to a reference point.
  • the measuring device is only in contact with the metal bath during measuring, and the problem of liquid metal becoming attached to the electrode and causing errors in level measurement is avoided. At the same time the need for maintenance is greatly reduced, since there are no parts of the measuring system which require to be taken up for inspection and cleaning.
  • the drawing illustrates a smelting furnace 1 with a crucible 2 full of liquid magnesium 3 with a temperature of 700 degrees C.
  • a lowering mechanism 4 On the outermost part of which there is provided an insulator 5.
  • a set of tongs or a claw 6 On to the insulator 5 there is attached a set of tongs or a claw 6 for introducing the bars 7 into the molten mass 3.
  • the relay 9 is further connected with the crucible 2, thus causing the circuit to be closed when the bar 7 touches the surface of the smelting bath 3.
  • a hydraulic cylinder 10 which is used for raising and lowering the lowering mechanism 4.
  • each bar and each casting is known in advance, thus enabling a control system (not shown) to regulate the supply of metal bars on the basis of the number of withdrawals from the smelting bath.
  • the control system will record the number of withdrawals from the molten mass. After a certain number of withdrawals, which correspond as closely as possible to the weight of a bar, the lowering mechanism will fetch a bar from a store (not shown) and lower it into the molten mass. Should the bar make contact during lowering before the high level switch is connected the level of the smelting bath is too high. There is therefore too much metal in the furnace and the control system will wait until a sufficient amount of metal has been removed. If the bar makes contact after the high level switch has been connected, but before the low level switch has been connected, the level of the smelting bath is correct. In this case the feeding in of metal bars will continue to be governed by the number of withdrawals. If the bar makes contact after both the high and the low level switches have been connected the level is too low. In this case the lowering mechanism fetches another bar and records the level once again. If the level is still too low, yet another bar is collected until the correct level is obtained.
  • the bars can, e.g., be fed into the molten mass by gravity from a pipe or a groove with an internal cross section which corresponds to the cross section of the bars, and with a shut-off arrangement for governing the feed rate.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Thermal Sciences (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)
  • Manufacture And Refinement Of Metals (AREA)

Abstract

Dans un procédé et un dispositif de mesure du niveau à la surface dans un bain de fusion (3) à haute température, et d'alimentation simultanée de métal brut sous la forme d'une barre de métal (7), laquelle est abaissée dans le bain de fusion (3) au moyen d'un mécanisme d'abaissement (4), le nombre de retraits du bain de fusion (3) commande l'introduction d'une nouvelle barre (7). La barre de métal qui alimente en métal brut le bain de fusion est isolée électriquement et constitue une électrode dans le système de mesure de niveau, et la masse de métal constitue la seconde électrode. Le fait d'abaisser la barre jusqu'à la surface du bain de fusion permet de mesurer le niveau en surface et le niveau du bain de fusion le plus bas, dont la mesure de niveau sert d'indication pour l'amenée d'une autre barre avant de faire couler le métal du bain de fusion.
PCT/NO1994/000202 1994-12-12 1994-12-12 Systeme de mesure de niveau pour bains de metal liquide WO1996018869A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
PCT/NO1994/000202 WO1996018869A1 (fr) 1994-12-12 1994-12-12 Systeme de mesure de niveau pour bains de metal liquide
AU13928/95A AU1392895A (en) 1994-12-12 1994-12-12 A level measurement system for liquid metal baths

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/NO1994/000202 WO1996018869A1 (fr) 1994-12-12 1994-12-12 Systeme de mesure de niveau pour bains de metal liquide

Publications (1)

Publication Number Publication Date
WO1996018869A1 true WO1996018869A1 (fr) 1996-06-20

Family

ID=19907753

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/NO1994/000202 WO1996018869A1 (fr) 1994-12-12 1994-12-12 Systeme de mesure de niveau pour bains de metal liquide

Country Status (2)

Country Link
AU (1) AU1392895A (fr)
WO (1) WO1996018869A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105583386A (zh) * 2016-02-29 2016-05-18 绍兴文理学院元培学院 一种热式压铸自动送料装置
CN107315428A (zh) * 2017-05-22 2017-11-03 江苏海鼎电气科技有限公司 一种多级触发液位控制器

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4223442A (en) * 1977-08-26 1980-09-23 British Steel Corporation Distance measurement
GB2109114A (en) * 1981-10-24 1983-05-25 Westofen Gmbh Metallurgical furnace

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4223442A (en) * 1977-08-26 1980-09-23 British Steel Corporation Distance measurement
GB2109114A (en) * 1981-10-24 1983-05-25 Westofen Gmbh Metallurgical furnace

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN, Vol. 13, No. 423, C-638; & JP,A,01 162 730 (SHINKO ELECTRIC CO LTD), 27 June 1989. *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105583386A (zh) * 2016-02-29 2016-05-18 绍兴文理学院元培学院 一种热式压铸自动送料装置
CN107315428A (zh) * 2017-05-22 2017-11-03 江苏海鼎电气科技有限公司 一种多级触发液位控制器

Also Published As

Publication number Publication date
AU1392895A (en) 1996-07-03

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