SU204503A1 - METHOD FOR TESTING FORMING AND GRANULAR MIXTURES - Google Patents

Description

A known method of testing molding and core mixtures by extrusion. The difference of the proposed method is the ability to determine the whole complex of properties of the molding and core mixtures used in pressing (specific compaction pressure, filling capacity - fluidity, mobility, elasticity, formability and specific compactability of the mixture). The specific compaction pressure is characterized by the ratio of the extrusion force required to compression to a predetermined degree of compaction to the pressure of the pressure. where is the specific compaction pressure, kg / cm; P is the pressing force, kg; F is the pressure area, slgs. The roll is determined by compressing a constant weight amount of the test mixture, which is sifted through a sieve into a cylindrical sleeve of a certain size. The compressed mixture is compacted sequentially, first to a predetermined minimum density in order to prepare the structure and eliminate the effect of pre-compaction, and then to maximum density. The sample strain rate is set the same for all tests. Filling capacity - the fluidity of the mixture is characterized by the ratio of the length of the branch portion of the sample resulting from filling and squeezing the mixture in the branch to the outer part, to the length of the side branch. where T is the fluidity (filling capacity), / d; / 2 - the length of the filled part of the sample, mm; / 1 is the length of the lateral branch, mm. A portion of the mixture is poured into the sleeve with a branch and sealed under the action of the compressive force necessary to seal to a given density. As the mixture is compressed at the level of the horizontal axis of the branch, lateral pressure occurs, under the action of which the branch is filled with the mixture and the mixture is compacted. In order to prevent the mixture from falling into a branch during the period of backfilling and pre-compaction, the side branch plunger is spring-loaded so that its movement is possible only with the application of a certain force.

The mobility of the mixture is characterized by the ratio of the height difference of the specimen with the minimum and maximum compaction wall obtained as a result of the action of the minimum compressive force to the whole deformation time of the mixture.

rm- 1 a,

-

where I am - the mobility of the mixture, mssek;

hi is the sample height at the preliminary degree of compaction, mm; / 1-2 - the height of the sample at a density corresponding to the specified, mm; I - deformation time, sec. In order to establish the mobility of the mixture, the weight amount of the mixture is compressed in the sleeve to the given densities and the height of the sample AI and / Z2 is reached under the action of the minimum compressive force, the value of which corresponds to the specified specific pressure of the seal.

The elasticity of the mixture is characterized by the ratio of the height increment of the sample sample after removal of the load to the full height of the compacted sample, achieved under the action of maximum compressive force.

fi - tii

a- U

100%,

100% L, U

where Y is the elasticity of the mixture ,,%;

V-i - the volume of the mixture at the final moment

application of load, Vz is the volume of the mixture after the load is removed,

SL43; / ii-height of the sample at the final moment

load application, mm; hz is the height of the sample after removal of the load, mm.

To determine the elasticity of the mixture, a constant weight amount of the mixture is poured into the sleeve and compressed under the action of maximum compressive force with a maximum deformation rate to the desired desired density, and then the load is quickly removed and the height of the sample is measured.

Specific compaction of the mixture is characterized by the ratio of the difference in height of the sample, corresponding to the minimum and maximum degrees of compaction of the mixture, to the value of the specific compaction pressure.

Mr. AI2

 B

jtiM, see where C is the specific density,

KZ

hi - sample height minimum

degrees of compaction, mm; hz - sample height at maximum

compressive force, mm RSHKS -maximum specific pressure

fines compaction. The height of AI is determined, then the weight is compressed by the action of maximum compressive force, also of constant magnitude, and the height of sample Aa is again determined.

At the final moment of compression of the sample, the value of the specific pressure of the seal is established using a specially calibrated sensor.

The formability of the mixture is characterized by the ratio of the density of the mixture in the least compacted central region of the sample to the density of the mixture in the most compacted upper region of the sample under the pressure plunger.

where e is the formability,%; bmna - density is minimal;

max - maximum density.

To determine the moldability, the mixture is precompacted by a compressive force of constant magnitude with a certain strain rate.

the sample is subjected to compression under the action of a force corresponding to the selected value of the specific compaction pressure and strain rate. The degree of compaction is established by

weighing the same volumes of the mixture or by micro-X-ray diffraction of a compacted sample of the mixture using X-ray microscopes with radioactive sources.

Subject invention

Claims (4)

1. Method of testing molding and core mixtures by extrusion, characterized by By the fact that, in order to determine the complex of properties of the molding and core mixtures, the samples are compressed and the specific compaction pressure is determined as the ratio of the pressing force to the area pressure of the sample to be compacted. 2. A method according to claim 1, characterized in that, in order to determine the filling capacity - the flowability of the mixture, the ratio of the length of the branch portion of the sample obtained in result of filling and compressing the mixture in the branch, to the total length of the side branch. 3. The method according to claim 1, characterized in that, in order to determine the mobility of the mixture, The ratio of the height difference of the specimen with the minimum and maximum degree of compaction obtained as a result of the action of the minimum compressive force to the whole deformation time of the mixture is determined. 4. A method according to claim 1, characterized in that, in order to determine the elasticity of the mixture, the ratio of the height increment of the sample of the mixture after removal of the load to the full height of the compacted sample is determined. 5 to determine the specific compactibility of the mixture, determine the ratio of the difference in sample height corresponding to the minimum and maximum degrees of compaction of the mixture to the value of the specific compaction pressure .5 6. The method according to claim 1, characterized in that with 6 the purpose of determining formability mixtures, determine the ratio of the density of the mixture in the least compacted central region of the sample to the density of the mixture in the most compacted upper region of the sample under the pressure plunger.