CN1014634B - Method and apparatus for fast testing air permeability of sand casting mould - Google Patents
Method and apparatus for fast testing air permeability of sand casting mouldInfo
- Publication number
- CN1014634B CN1014634B CN 90106591 CN90106591A CN1014634B CN 1014634 B CN1014634 B CN 1014634B CN 90106591 CN90106591 CN 90106591 CN 90106591 A CN90106591 A CN 90106591A CN 1014634 B CN1014634 B CN 1014634B
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- China
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- pressure
- value
- sand
- gas
- sample
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Abstract
The present invention relates to a novel method for quickly measuring moulding sand mould permeability. In the method, a pneumatic supply with certain volume and certain initial pressure exhaust gas through an exhaust valve and sand specimens or casting moulds; when the pressure of the pneumatic supply is reduced to a certain pressure value P-[1], timekeeping is started; the pressure of the pneumatic supply is reduced from P-[1] to P-[2] after the time of delta t; when the physical dimension and the compaction degree of the sand specimens as well as the initial pressure and the variation range of the pressure (P-[1] to P-[2]) of the pneumatic supply are fixed values, the exhaust time O delta t only corresponds to the permeability K of the sand specimens; the method for measuring the permeability has the advantages of simple and portable device and accurate measurement.
Description
The invention belongs to modern casting test method, be used for that cast moulding (core) sand is wet, the fast measuring of drying permeability and mould permeability, also can be used as the usefulness that other industry detects the gas penetration potential of material and goods.
Molding sand is the main Modeling Material in the Foundry Production in modern age, and gas penetration potential (K commonly used represents) is one of main performance index of molding sand (especially green-sand), and the quality of mould permeability will directly have influence on the quality and the throughput rate of foundry goods.At present, air bell formula or electric fan formula gas penetration potential fast measuring instrument that the domestic and international casting industry of quilt generally adopts, and other forms of permeability meter, be ultimate principle all with constant voltage source of the gas exhaust manometry, thus apparatus structure complexity, volume big, carry and operate very inconvenient.In addition, test required standard sand sample, on the paddle type mill proof press of heaviness, make, therefore, can not satisfy the on-the-spot requirement of fast measuring molding sand mould permeability whenever and wherever possible of casting.
Purpose of the present invention, be to provide a kind of new method of convenient and practical detection gas penetration potential for casting industry, based on this, portable intelligent molding sand (casting mold) gas penetration potential fast measuring instrument simple in structure, processing ease be can design and produce, thereby the real-time measurement and the control problem of gas penetration potential solved.
Major technique of the present invention thes contents are as follows:
The first, the new method with transformation source of the gas exhaust timing method mensuration gas penetration potential is proposed.
The method that transformation source of the gas exhaust timing method is measured gas penetration potential is to allow a pneumatic supply with certain volume and certain original pressure by vent valve and sand sample (or casting mold) exhaust, when bleed pressure is reduced to a certain pressure value P
1The time, pick up counting, after the Δ t time, bleed pressure will be from P
1Reduce to P
2At sand sample physical dimension, consolidation degree, source of the gas original pressure and bleed pressure variation range (P
1-P
2) be under the situation of fixed value, exhaust timing time Δ t is with only relevant with the gas penetration potential K value of sand sample.For the mensuration of mould permeability,, can not consider the influence of casting mold physical dimension because of the exhaust mode difference.Therefore, as long as record Δ t value exactly, can measure gas penetration potential K value (this method survey gas penetration potential ultimate principle can referring to accompanying drawing 1).Because this new method does not need the constant voltage source of the gas, so the proving installation structure is greatly simplified, volume dwindles greatly, and is convenient to realize the computerization of instrument.
The second, for realizing the new method design and producing portable intelligent molding sand (casting mold) gas penetration potential fast measuring instrument.
This instrument is made up of air-channel system and computer data acquiring and disposal system two large divisions.Air-channel system comprises that mainly definite value air storage chamber 1, aerator 4, pressure limiting valve 3, elasticity sample cylinder base 5(include vent valve), sand sample tube 6 or 7, casting mold probe 8 etc., to finish the once inflation and the exhaust process of transformation source of the gas.Computer data acquiring and disposal system mainly comprise gas micro-pressure sensor 2, data amplifier 9, analog to digital converter 10, one-chip computer 14, memory under program 13, interface circuit 15, keyboard 16, digital indicator 17, power supply 11 and 12 etc., to finish the monitoring that bleed pressure is changed, (block diagram of system are referring to the accompanying drawing 2) such as high-precision timing, the calculating of gas penetration potential K value and demonstrations as a result of exhaust process.
The 3rd, for satisfying needs, design and produce spring automatic constant-pressure formula fast sampler in casting fast-field evaluation sand permeability.
Conventional paddle type mill proof press not only weight big, carry inconvenience, and sample preparation yield rate low (especially when the molding sand compact rate of molding changed greatly, the sand sample height error is difficult to be controlled), troublesome poeration.Therefore, sample preparation speed is low.Spring automatic constant-pressure formula fast sampler has the fireballing characteristics of sample preparation easy to carry, simple to operate.This sampler is formed (structure diagram is referring to accompanying drawing 4) by main body sample tube 6, auxiliary sample tube 27, outer sleeve 28, sample tube base 29 and spring automatic constant-pressure formula compactor.Its method for making sample is as follows, at first main body sample tube and auxiliary sample wound packages is gone in the outer sleeve, and seat fills up loose molding sand then in tube on base, presses sand with spring automatic constant-pressure formula compactor, stops firmly when pressure head push rod 23 is all withdrawn.At this moment, the part molding sand in the auxiliary sample tube is pressed into main body sample tube.Imitative this is pressed sand three times, can guarantee that the molding sand in the main body sample tube obtains a degree of packing of fixing down in certain external force (length of spring compressed length is certain) effect.Take off outer sleeve, remove auxiliary sample tube, wipe main body sample tube end face molding sand simultaneously off, take off sample tube base at last, promptly accuse sample preparation and finish.This shows,, not only need not weigh, and can once become sample with the sample preparation of spring automatic constant-pressure formula fast sampler.Therefore can improve sample preparation speed greatly.
The present invention compared with prior art has following major advantage:
The first, can make permeability meter and sampler volume little, in light weight, easy to carry.Physical dimension, the weight contrast of permeability meter that adopts new method and manufacture and design and sampler and the air bell formula permeability meter that generally adopts at present, electrodynamic type permeability meter and three hammer sampling machines see Table 1.
The second, can improve the intelligent degree of test speed and instrument.Conventional permeability meter sample preparation and test operation are more numerous, and test result is readability not, and test speed is low.And the present invention once becomes sample with fast sampler, adopts computing machine to carry out data acquisition and processing, and the gas penetration potential value is directly shown by numeral, thus the intellectuality that has improved test speed and instrument.
The 3rd, can improve test resolving power and measuring accuracy.Conventional constant voltage source of the gas exhaust manometry is that the pressure reduction with 0～100mm water column is divided into 100 parts, and resolving power is 1/100, and is 5000 between maximum count value of the present invention and the least count value, so resolving power is 1/5000.In addition, the present invention utilizes two pressure value P
1And P
2As timing initial sum termination signal, the pressure measurement error that test macro causes owing to temperature factor such as float to the accuracy of timing almost not influence (because of P
1And P
2Change in the same way simultaneously), thereby make instrument have higher measuring accuracy.Adopt air bell formula, electrodynamic type and novel ventilated property analyzer, the data table of comparisons that same molding sand and casting mold is carried out the hygrometric state ventilation characteristic measuring sees Table 2.As can be seen, new instrument has repeatability preferably.
The 4th, can make Instrument Manufacturing Technique simple, be convenient to tissue production.Conventional permeability meter and sampling machine complex structure, nonstandard parts are difficult for processing, production cost height.And according to the designed permeability meter of the present invention, processing component is very few, and electronic circuit adopts the modular design manufacturing simple, and debugging is convenient, and cost is low, helps tissue production.
Accompanying drawing 1 the present invention measures molding sand (casting mold) gas penetration potential schematic diagram
(a) bleed pressure change curve in time
(b) gas penetration potential value K and exhaust timing time curve
The P bleed pressure, t evacuation time, P
sThe initial discharge pressure of source of the gas, P
oThe minimum initial discharge pressure of the source of the gas that is set, P
1The pressure of source of the gas when timing begins, P
2The pressure of source of the gas when timing stops, K gas penetration potential value, Δ t exhaust timing time.
The used portable intelligent molding sand of accompanying drawing 2 the present invention mould permeability analyzer is formed block scheme
The used portable intelligent molding sand of accompanying drawing 3 the present invention mould permeability analyzer electrical schematic diagram
The used spring automatic constant-pressure of accompanying drawing 4 the present invention formula fast sampler structure principle chart
1 definite value gas dome, 2 gas micro-pressure sensors, 3 pressure limiting valves, 4 aerators, 5 elasticity sample cylinder bases (including vent valve), 6 wet sample tubes (main body sample tube) and damp sand sample, 7 dry sample tubes and dry sand sample, 8 casting molds probe, 9 data amplifiers, 10 analog to digital converters, 11 bridge circuit power supply (V
2), 12 system power supply (V
1), 13 memory under programs, 14 one-chip computers, 15 interface circuits, 16 keyboards, 17 digital indicators, 18 master gauges, 19 compactor end caps, 20 compaction force regulation cocks, 21 compactor outer sleeves, 22 springs, 23 pressure head push rods, 24 sealing rings, 25 gland bonnets, 26 compactor pressure heads, 27 auxiliary sample tubes, 28 outer sleeves, 29 sample tube bases.
Most preferred embodiment of the present invention
One, measures molding sand (casting mold) gas penetration potential with transformation source of the gas exhaust timing method
Allow one to have certain volume V and certain original pressure P
sPneumatic supply by vent valve and sand sample (or casting mold) exhaust, when bleed pressure by P
sReduce to P
1In time, pick up counting, and reduces to P
2The time stop timing, evacuation time Δ t when succeeding in one's scheme, this Δ t value promptly characterizes sand sample (or casting mold) gas penetration potential value K.P
sValue is stabilized in certain pressure limit by pressure limiting valve.Only work as P
s〉=P
oThe time, timekeeping system can be worked.If bleed pressure P
sSurpass voltage limiting value (P
o+ Δ P), then pressure limiting valve begins quick exhaust, until making P
s-P
o＜P
oFor the superpressure value (P after the pressure limiting adjusting
s-P
o), can further be revised by computer software, thereby be guaranteed the original pressure basic fixed of exhaust each time.
Two, portable intelligent molding sand (casting mold) permeability meter
Novel ventilated property analyzer comprises air-channel system and computer data acquiring and disposal system two large divisions.
Make airtight gas dome 1 with galvanized iron sheet (other sheet metals also can), offer a macropore on the one end cap, in order to inlay gas micro-pressure sensor 2, the other end covers offers four apertures, wherein two holes link to each other with elasticity sample cylinder base 5 with aerator 4 respectively by flexible rubber hose, aerator 4 with the medical sphygmomanometer glueballs for it.Two holes connect pressure limiting valve 3 and master gauge 18 respectively in addition, and master gauge is only made the usefulness of demarcation, after waiting to finish demarcation, will connect the aperture sealing of master gauge.During test, glueballs of pinching can make bleed pressure P
s＞P
o, in the process of vent valve and sand sample exhaust, the variation of its pressure becomes the variation of voltage by micro-pressure sensor 2 at source of the gas, and delivers to computer data acquiring and disposal system (referring to accompanying drawing 2).
The computer data acquiring of novel ventilated property analyzer and the composition of disposal system are shown in accompanying drawing 2, accompanying drawing 3.Gas micro-pressure sensor 2 is made of beryllium-bronze flexible sheet and the quick electric bridge of silicon power, and arm resistance and bridge circuit are respectively R with potentiometer
1～R
4And RW
1Data amplifier 9 is by a slice single supply four high guaily unit integrated chip LM324; Resistance R
11～R
18And capacitor C
5Constitute.Analog to digital converter 10 is by ADC0804 chip and R
12, C
9Constitute.One-chip computer 14 is 8031 of a MCS-51 series, and clock is connected into the internal oscillator mode, and outward element is 6MHZ crystal oscillator and C
6, C
7Memory under program 13 is 2732 chips of 4K byte, and internal writer and mathematical model (Δ t-K curve) link to each other with 8031 by address latch 74ls373.Interface circuit 15 is by a slice 8155 extenders and C
10, R
22Constitute.Display 17 is by four eight sections altogether cloudy charactrons, two rp-drive 74LS06 and R
29～R
36Constitute.Keyboard 16 is by keyswitch K
1～K
7, R
19, R
20, R
23～R
28, C
8Constitute, seven buttons are respectively " O " (zeroing) key, " B " (demarcation) key, " X " (of bonding) key, " K
1" (K=0～100) key, " K
2" (K=101～700) key, " K
3" (K=701～2450) key and " * " (resetting) key.Power supply 12(11) by the stacking battery of 9V, three-terminal voltage-stabilizing sheet 7805(7806), filter capacitor C
1, C
2(C
3, C
4) and under-voltage indicating circuit R
5, R
6, R
7, D
1, T
1, T
2, RW
2(R
8, R
9, R
10, D
2, T
3, T
4, R
W3) form.When dropping to a certain numerical value, cell voltage (can pass through potentiometer R
W2, R
W3Regulate) time, D
1(D
2) promptly can be luminous, the prompting user changes battery.If there is AC power at the use scene, also can pass through socket J
1(J
2) access 12V D.C. regulated power supply (purchasing in addition).System work process is as follows, the variation of bleed pressure in the receptacle compartments 1 is converted to the variation of voltage signal by gas micro-pressure sensor 2, after this voltage signal enters data amplifier 9 and is exaggerated, directly send analog to digital converter 10 to carry out the A/D conversion, digital quantity after the conversion is delivered to and is carried out various identifications in the single-chip microcomputer 14, and the discovery bleed pressure is reduced to P
1Automatically pick up counting, reduce to P
2The time stop timing, according to gained clocking value Δ t be pre-stored in mathematical model (Δ t-K curve) in the memory under program 13, gas penetration potential K value can be searched and calculate to computing machine, and show by display 17.
Three, spring automatic constant-pressure formula fast sampler
Auxiliary sample tube 27 and main body sample tube 6 process for stainless-steel tube, outer sleeve 28 is a plastic tube, sample tube base 29 is for aluminium alloy processes, and spring automatic constant-pressure formula compactor is made up of pressure head 26, pressure head push rod 23, compactor outer sleeve 21, spring 22, compaction force regulation cock 20, compactor end cap 19, sealing ring 24 and gland bonnet 25.Seal ring material is polyfoam (sponge), and its effect is to prevent that sand grains and dust from entering compactor and increase frictional resistance (structure is referring to accompanying drawing 4) between push rod and the sleeve
Four, scaling method of the present invention
Scaling method of the present invention is that the molding sand of preparation heterogeneity is produced dry sample, wet sample and casting mold respectively.At first on air bell formula permeability meter, survey its gas penetration potential K value with standard law, get molding sand of the same race then, directly measure with the fast sampler sample preparation of spring automatic constant-pressure formula or with the casting mold probe, select " demarcation " (B key) function of instrument, measure evacuation time Δ t.Make K-Δ t relation curve by many groups Δ t, K Value Data.For improving the measuring accuracy and the test speed of instrument, the sand permeability value is divided into three grades, i.e. K
1=0～100, K
2=101～700, K
3=701～2450, take different clocking methods and time of day respectively.Finally can obtain four Δ t-K curves (three of sand samples, one on casting mold), they are deposited in the memory under program, be the used mathematical model of the present invention.
Five, the fast measuring of test case of the present invention-hygrometric state clay-bonded sand gas penetration potential
(1) instrument zero self check
Turn on the power switch, instrument display monitoring prompt-" P " presses " 0 " (zeroing) key, and the instrument display digit should change between " 0-00 " and " 0-01 ", otherwise should regulate bridge circuit potentiometer RW
1, mix up the back and reset by " * " key.
(2) empty exhaust self check
Under monitor state (prompt is " P "), press " B " (demarcation) key, instrument shows " 0000 ", pinching inflation glueballs once is inflated to and presses back (P
s〉=P
o), show " Good " character, carry out with exhaust, display will dynamically show the time counting value, after exhaust finished, count value should be " 500 " (± 5), otherwise should regulate the throughput of elasticity sample cylinder base vent valve.
(3) produce sample
With main body sample tube, auxiliary sample wound packages is gone in the outer sleeve, and is seated on the sample tube base.Fill up molding sand in the sample tube, slowly press sand with spring automatic constant-pressure formula compactor, stop when the compactor push rod is all withdrawn firmly, imitative this is pressed sand three times, takes off outer sleeve, removes auxiliary sample tube, wipes main body sample tube end face molding sand off, takes off sample tube base.
(4) ventilation characteristic measuring
The main body sample tube that installs sand sample is tightened on the elasticity sample cylinder base, and (prompt is " P ") presses " K under monitor state
2" (K=107～700) key, display shows " 2-00 ", pinching inflation glueballs once, be inflated to pressure after, display shows " Good ".After this, carry out with exhaust, display dynamically shows the evacuation time count value, treat that exhaust process finishes after, show gas penetration potential K value.If evacuation time is too short, gas penetration potential K value is described greater than 700, then instrument shows " 3-00 ", prompting operation person is again by " K
3" key measures.Otherwise then instrument shows " 1-00 ", and prompting operation person is again by " K
1" key measures.
Claims (2)
1, a kind of method of fast measuring molding sand mould permeability may further comprise the steps:
A, allow a pneumatic supply by vent valve and sand sample or casting mold exhaust with certain volume and certain original pressure;
B, when bleed pressure is reduced to a certain pressure value P 1, pick up counting, after the △ t time, bleed pressure is reduced to P2 from P1, be under the situation of fixed value in sand sample physical dimension, consolidation degree, source of the gas original pressure and bleed pressure variation range (P1-P2), △ t is only relevant with the gas penetration potential K value of sand sample between the timing of exhaust meter;
C, record △ t value exactly and can measure gas penetration potential K value.
2, a kind of portable intelligent molding sand mould permeability fast measuring instrument, form by air-channel system and computer data acquiring and disposal system, it is characterized in that air-channel system comprises definite value air storage chamber 1, aerator 4, pressure limiting valve 3, elasticity sample cylinder base 5, sand sample tube 6 or 7, casting mold probe 8, to finish the once inflation and the exhaust process of transformation source of the gas; Computer data acquiring and disposal system comprise gas micro-pressure sensor 2, data amplifier 9, analog to digital converter 10, one-chip computer 14, memory under program 13, interface circuit 15, keyboard 16, data display equipment 17, power-supply circuit, to finish the monitoring that bleed pressure is changed, high-precision timing and the calculating of gas penetration potential K value and result's demonstration of exhaust process.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 90106591 CN1014634B (en) | 1990-07-31 | 1990-07-31 | Method and apparatus for fast testing air permeability of sand casting mould |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 90106591 CN1014634B (en) | 1990-07-31 | 1990-07-31 | Method and apparatus for fast testing air permeability of sand casting mould |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1049055A CN1049055A (en) | 1991-02-06 |
| CN1014634B true CN1014634B (en) | 1991-11-06 |
Family
ID=4880178
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 90106591 Expired CN1014634B (en) | 1990-07-31 | 1990-07-31 | Method and apparatus for fast testing air permeability of sand casting mould |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1014634B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103048255A (en) * | 2012-12-27 | 2013-04-17 | 南昌航空大学 | Device and method for testing air permeability of investment precision casting shells |
Families Citing this family (6)
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|---|---|---|---|---|
| CN102519854A (en) * | 2011-12-06 | 2012-06-27 | 鲁东大学 | Soil gas conductivity measuring meter |
| CN102998160B (en) * | 2012-12-31 | 2014-09-17 | 哈尔滨理工大学 | Cylindrical sample preparation device for measuring moisture content of green sand through capacitance method and method for measuring moisture content of green sand |
| CN104950075A (en) * | 2015-04-24 | 2015-09-30 | 北京仁创科技集团有限公司 | Detection device and detection method for detecting flue gas released during coated sand casting |
| CN105158145B (en) * | 2015-10-09 | 2018-03-23 | 浙江佳力风能技术有限公司 | Resin-bonded sand cast form surface degree of packing assay method |
| CN110879188B (en) * | 2019-11-28 | 2020-10-09 | 山东科技大学 | Movable rapid coal and rock permeability measuring instrument |
| CN110887717B (en) * | 2019-12-30 | 2022-07-05 | 江苏省水文地质工程地质勘察院 | Sample preparation method of sandy soil sample preparation device capable of preparing samples uniformly |
-
1990
- 1990-07-31 CN CN 90106591 patent/CN1014634B/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103048255A (en) * | 2012-12-27 | 2013-04-17 | 南昌航空大学 | Device and method for testing air permeability of investment precision casting shells |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1049055A (en) | 1991-02-06 |
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