阅读说明：本技术 一种用于动态测试液体反应模塑成型收缩的装置与方法 (Device and method for dynamically testing liquid reaction molding shrinkage ) 是由 杨卫民 宋乐 谢鹏程 丁玉梅 于 2019-10-09 设计创作，主要内容包括：本发明提出一种用于动态测试液体反应模塑成型收缩的装置与方法,装置包括底座、测试腔固定座、测试腔、环形柱塞、四个气缸、进样柱塞、电动缸固定座、电动缸、联轴器、位移传感器、电加热器、进样阀和待测试样组成。通过上移圆柱形柱塞将试样吸入圆柱形空腔并进行初步的计量并预热到反应温度；把试样推动到圆柱形柱塞周围的环形空腔中,并推动环形柱塞向上运动,试样在测试温度下的精确体积可以由环形柱塞的位移准确测量,实时监测环形柱塞位移,即可求得试样的实时收缩率,试样体积的计量与测量是在加热至温度稳定后进行,避免了热膨胀对测试过程的干扰；柱形柱塞下压到底可以将进样管道与待测试样完全隔离,避免了管道内残存液体对测试的干扰。(The invention provides a device and a method for dynamically testing liquid reaction molding shrinkage. Sucking a sample into the cylindrical cavity by moving the cylindrical plunger upwards, performing primary metering and preheating to a reaction temperature; the sample is pushed into an annular cavity around the cylindrical plunger and the annular plunger is pushed to move upwards, the accurate volume of the sample at the test temperature can be accurately measured by the displacement of the annular plunger, the displacement of the annular plunger is monitored in real time, the real-time shrinkage rate of the sample can be obtained, the measurement and measurement of the volume of the sample are carried out after the sample is heated to the stable temperature, and the interference of thermal expansion to the test process is avoided; the cylindrical plunger is pressed to the bottom, so that the sample introduction pipeline can be completely isolated from a sample to be tested, and the interference of residual liquid in the pipeline to the test is avoided.)

1. An apparatus for dynamically testing liquid reaction molding shrinkage, characterized by: the method mainly comprises the following steps: the device comprises a base, a test cavity fixing seat, a test cavity, an annular plunger, four cylinders, a sample injection plunger, an electric cylinder fixing seat, an electric cylinder, a coupler, a displacement sensor, an electric heater, a sample injection valve and a sample to be tested, wherein the base is a round thick rigid flat plate and is placed on the surface for placing the device; the testing cavity fixing seat is a metal cylinder with an upright axis, the lower part of the cylinder is provided with four supporting legs, the center of the upper surface of the cylinder is provided with an internal thread blind hole, the bottom surface of the blind hole is a plane, the center of the blind hole is provided with a tiny through hole, the four supporting legs of the testing cavity fixing seat are welded and connected with the base, and the testing cavity fixing seat is coaxial with the base; the testing cavity is a round pipe with a smooth inner surface, the lower part of the round pipe is provided with an external thread, the testing cavity is connected with the testing cavity fixing seat through the external thread, and the external thread is fully sealed by sealant; the annular plunger is a pipe with smooth inner and outer surfaces, the pipe is vertically arranged, the upper end of the annular plunger is connected with a flange with a larger diameter, the flange is provided with four threaded holes along the circumference, the outer surface of the lower end of the pipe is precisely matched with the inner surface of the test cavity, and the annular plunger can freely slide up and down while ensuring sealing; the four cylinders are double-acting cylinders which can provide tension or pressure after being inflated, the four cylinders are uniformly distributed along the circumference of the base, the axes of the four cylinders are vertically arranged on the upper surface of the base, the bottom surface of the cylinder body is connected with the base through threads, and cylinder rods of the four cylinders are connected with threaded holes in a flange of the annular plunger through threads at the top of the cylinder rods; the sample injection plunger is a cylinder with a smooth outer surface, the outer surface of the lower end of the sample injection plunger is precisely matched with the inner surface of the tube of the annular plunger, the sample injection plunger can freely slide up and down while the sealing is ensured, and the upper end of the sample injection plunger is provided with an external thread; the electric cylinder fixing seat is a thicker rigid circular plate, a larger hole is formed in the middle of the circular plate, four supporting legs are uniformly distributed on the lower surface of the circular plate along the circumference, and the electric cylinder fixing seat is fixed on the base through the four supporting legs in a welding mode and is coaxial with the base; the electric cylinder is an electric servo push rod capable of precisely controlling displacement, and is coaxially fixed on the electric cylinder fixing seat through a bolt at the end part of the cylinder body, and the push rod of the electric cylinder faces downwards; the coupler is a rigid short pipe, an inner hole is provided with threads, and the push rod of the electric cylinder is connected with the sample injection plunger through the threads by the coupler; the displacement sensor is vertically fixed on the electric cylinder fixing seat, and the test probe can detect the relative displacement of the annular plunger relative to the electric cylinder fixing seat; the electric heater is an annular electric heating ring capable of accurately controlling temperature, the annular electric heating ring is wrapped on the outer surface of the test cavity, the sample injection valve is a stop valve and is connected with a through hole of the test cavity fixing seat through welding, and the lower end of the stop valve is connected with a pipeline for conveying liquid to be tested; the liquid to be tested is the resin liquid to be tested, is input through a pipeline connected below the sample injection valve, and is filled in a cavity formed by the test cavity fixing seat, the test cavity, the annular plunger and the sample injection plunger during testing.

2. The apparatus for dynamically testing liquid reaction molding shrinkage of claim, wherein: the lower end of a push rod of the electric cylinder can be welded with a flange plate; the servo motor is a motor with controllable rotating speed, the motor body is fixed on the flange plate by using bolts, and the shaft of the servo motor faces downwards; the lower end of the shaft of the servo motor is provided with threads and is connected with the upper end of the sample injection plunger through the threads of the coupler.

3. A method for dynamically testing liquid reaction molding shrinkage, characterized by: before testing, the four cylinders retract to enable the annular plunger piston to move downwards to the lowest end, the push rod of the electric cylinder extends downwards to enable the sampling plunger piston to move to the lowest end, the sampling valve is closed, and liquid to be tested with certain pressure is filled in a pipeline at the lower part of the sampling valve; the first step is the expected dose: the sample injection valve is opened, a push rod of the electric cylinder moves upwards by a displacement through servo control, so that the sample injection plunger is driven to move upwards by the same displacement, a sample to be tested enters a cylindrical cavity formed by the upward movement of the plunger under the action of the self pressure, and the four cylinders are locked or output enough tension, so that the annular plunger is kept at the lowest position; the second step is preheating: heating the sample to be measured to the temperature required by curing by using an electric heater, and metering in the third step: the sample injection valve is closed, the four cylinders respectively output a downward force by controlling air pressure, the annular plunger piston is subjected to a downward total force, meanwhile, the push rod of the electric cylinder pushes the sample injection plunger piston to slowly press downwards, the sample injection plunger piston presses a sample to be detected below into an annular cavity around the sample injection plunger piston and pushes the annular plunger piston upwards, finally, the sample injection plunger piston presses downwards to the bottommost end, all the sample to be detected is pressed into the annular cavity around the sample injection plunger piston, the upward displacement of the annular plunger piston can be accurately measured by a displacement sensor, and then the total volume of the sample after being heated is calculated; the fourth step is testing: the downward pressure of the annular plunger is kept, the data of the displacement sensor is collected in real time, at the moment, the volume of the sample to be detected shrinks due to the fact that the sample to be detected undergoes a curing reaction at the testing temperature, the curing shrinkage rate is further solved by measuring the downward displacement change value of the annular plunger, and the function curve of the shrinkage rate of the sample to be detected to the time is obtained through real-time dynamic data collection of the displacement sensor.

4. A method for dynamically testing liquid reaction molding shrinkage according to claim 3, wherein: in the test process, the servo motor rotates to drive the sampling plunger to rotate, so that the inner wall and the outer wall of a sample to be tested rotate relatively, the shearing orientation of the molecular chains in the sample curing process is controlled by controlling the time and the speed of the relative rotation, and the action rule of the sheared sample on the shrinkage performance of the sample is further researched.

Technical Field

The invention relates to a device and a method for dynamically testing liquid reaction molding shrinkage, belonging to the field of measurement and testing.

Background

Liquid reaction molding is a process in which a liquid resin material is injected into a mold, and the liquid resin material is cured by heating or by mixing two active ingredients, thereby finally forming a solid product. The outstanding characteristic of the reaction is that the chemical reaction is accompanied in the forming process, so that large shrinkage is generated, and the dimensional accuracy of the product is further influenced. Therefore, the dynamic shrinkage curve of the resin during the curing process is of great significance to the formulation of a specific process, and the development of appropriate equipment for testing the resin is necessary.

The plunger-cylinder method is the most commonly used shrinkage test method, and the dynamic shrinkage curve of the sample can be obtained by using a piston and a piston cylinder to compact the sample and measuring the displacement of the piston during the curing process. This type of approach has some drawbacks. Firstly, in the method, a liquid resin sample needs to be sucked into a piston cylinder through a related pipeline, and the resin in the pipeline also shrinks, so that the final test value is interfered; secondly, in the processing process, a lot of samples need to be heated to a certain reaction temperature, the thermal expansion and the reaction shrinkage of the samples are finally reflected on a shrinkage curve, and the thermal expansion and the reaction shrinkage interfere with each other, so that the real reaction shrinkage is difficult to obtain in the actual operation; therefore, there is a need for a testing apparatus and method that removes thermal expansion from interfering with the extra resin in the pipe to accurately determine shrinkage during the reaction.

Disclosure of Invention

The invention provides a device and a method for dynamically testing liquid reaction molding shrinkage, wherein the testing device comprises a cylindrical testing cavity, and an annular plunger and a cylindrical plunger which are matched with the cylindrical testing cavity; then the cylindrical plunger is pressed downwards, the sample is pushed into an annular cavity around the cylindrical plunger, the annular plunger is pushed to move upwards, the accurate volume of the sample at the test temperature can be accurately measured by the displacement of the annular plunger, the displacement of the annular plunger is monitored in real time in the curing process, the real-time shrinkage rate of the sample can be obtained, the measurement and the measurement of the volume of the sample are carried out after the sample is heated to the stable temperature, and the interference of thermal expansion on the test process is avoided; the cylindrical plunger is pressed to the bottom, so that the sample introduction pipeline can be completely isolated from a sample to be tested, and the interference of residual liquid in the pipeline on the test is avoided.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows: a device for dynamically testing liquid reaction molding shrinkage mainly comprises: the device comprises a base, a test cavity fixing seat, a test cavity, an annular plunger, four cylinders, a sample injection plunger, an electric cylinder fixing seat, an electric cylinder, a coupler, a displacement sensor, an electric heater, a sample injection valve and a sample to be tested. Wherein the base is a round thick rigid flat plate and is arranged on the surface for placing the instrument; the testing cavity fixing seat is a metal cylinder with an upright axis, the lower part of the cylinder is provided with four supporting legs, the center of the upper surface is provided with an internal thread blind hole, the bottom surface of the blind hole is a plane, the center is provided with a tiny through hole, the four supporting legs of the testing cavity fixing seat are welded with the base, and the testing cavity fixing seat is coaxial with the base; the testing cavity is a round pipe with a smooth inner surface, the lower part of the round pipe is provided with an external thread, the testing cavity is connected with the testing cavity fixing seat through the external thread, and the external thread is fully sealed by sealant; the annular plunger is a pipe with smooth inner and outer surfaces, the pipe is vertically arranged, the upper end of the annular plunger is connected with a flange with a larger diameter, the flange is provided with four threaded holes along the circumference, the outer surface of the lower end of the pipe is precisely matched with the inner surface of the test cavity, and the annular plunger can freely slide up and down while ensuring sealing; the four cylinders are double-acting cylinders which can provide tension or pressure after being inflated, the four cylinders are uniformly distributed along the circumference of the base, the axis of the four cylinders is vertically arranged on the upper surface of the base, the bottom surface of the cylinder body is connected with the base through threads, and cylinder rods of the four cylinders are connected with threaded holes in a flange of the annular plunger through threads at the top of the cylinder rods; the sample injection plunger is a cylinder with a smooth outer surface, the outer surface of the lower end of the sample injection plunger is precisely matched with the inner surface of a pipe of the annular plunger, the sample injection plunger can freely slide up and down while sealing is ensured, and the upper end of the sample injection plunger is provided with an external thread; the electric cylinder fixing seat is a thicker rigid circular plate, a larger hole is formed in the middle of the circular plate, four supporting legs are uniformly distributed on the lower surface of the circular plate along the circumference, and the electric cylinder fixing seat is fixed on the base through the four supporting legs in a welding mode and is coaxial with the base; the electric cylinder is an electric servo push rod capable of precisely controlling displacement, and is coaxially fixed on the electric cylinder fixing seat through a bolt at the end part of the cylinder body, and the push rod of the electric cylinder faces downwards; the coupler is a rigid short pipe, an inner hole is provided with threads, and the push rod of the electric cylinder is connected with the sample injection plunger through the threads by the coupler; the displacement sensor is vertically fixed on the electric cylinder fixing seat, and the test probe can detect the relative displacement of the annular plunger relative to the electric cylinder fixing seat; the electric heater is an annular electric heating ring capable of accurately controlling temperature, the annular electric heating ring is wrapped on the outer surface of the test cavity, the sample injection valve is a stop valve and is connected with a through hole of the test cavity fixing seat through welding, and the lower end of the stop valve is connected with a pipeline for conveying liquid to be tested; the liquid to be tested is the resin liquid to be tested, is input through a pipeline connected below the sample injection valve, and is filled in a cavity formed by the test cavity fixing seat, the test cavity, the annular plunger and the sample injection plunger during testing.

The invention provides a method for dynamically testing liquid reaction molding shrinkage, wherein before testing, four cylinders retract to enable an annular plunger piston to move downwards to the bottommost end, a push rod of an electric cylinder extends downwards to enable a sample injection plunger piston to move to the lowest point, a sample injection valve is closed, and a pipeline at the lower part of the sample injection valve is filled with liquid to be tested with certain pressure; the first step of the test is pre-measurement, in the step, a sample injection valve is opened, a push rod of an electric cylinder moves upwards by a displacement L1 through servo control, and further drives a sample injection plunger to move upwards by a displacement L1, a sample to be tested enters a cylindrical cavity formed by the upward movement of the plunger under the action of self pressure, in the step, the volume of the sample to be tested is preliminarily controlled by controlling the displacement L1, and in the step, four cylinders are locked or output enough tension to keep the annular plunger at the lowest position; the second step of the test is preheating, in this step, the electric heater is used to heat the sample to be tested to the temperature required by solidification, in this step, the heating rate can be controlled to make the temperature rise process of the sample to be tested consistent with that in the injection machine cylinder under the production condition so as to better reflect the real production process; the third step of the test is metering, in this step, the sampling valve is closed, the four cylinders respectively output a downward force F by controlling the air pressure, the annular plunger is subjected to a downward total force fsotai equal to 4 · F, meanwhile, the push rod of the electric cylinder pushes the sampling plunger to slowly press downward, the downward pressing of the sampling plunger presses the lower sample to be tested into the annular cavity around the sampling plunger and pushes the annular plunger upward, finally, the sampling plunger presses downward to the bottom end, all the samples to be tested are pressed into the annular cavity around the sampling plunger, the upward displacement L2 of the annular plunger can be accurately measured by the displacement sensor, and then the total volume vsotai equal to L2 · S after the sample is heated, wherein S is the sectional area of the annular section, in this step, the pressure of the lower sample is constantly equal to fsotai because the downward pressure of the annular plunger is fsotai, wherein S is the sectional area of the annular section, the pressure P of the sample can be equal to the pressure in the mold filling process in the real production process by controlling the downward pressure F total of the annular plunger, and the shearing rate of the liquid to be measured during flowing is controlled to be equal to the shearing rate in the mold filling process of liquid reaction molding forming by controlling the downward pressing speed of the sampling plunger so as to better reflect the real production process; the fourth step of the test is that the downward pressure of the annular plunger is kept as F total, the pressure of the lower sample is constant as P ═ F total/S, at the moment, the data of the displacement sensor is collected in real time, at the moment, the sample to be tested is subjected to a curing reaction at the test temperature, the volume is contracted, the size delta V of the volume contraction can be obtained by measuring the downward displacement delta L of the annular plunger, and further the curing shrinkage factor is obtained, wherein delta V/V total is obtained by real-time dynamic data collection of the displacement sensor, the shrinkage factor of the sample to be tested can be obtained as a function curve of time, in the step, the sampling plunger is positioned at the lowest point, the sampling valve and the related sample conveying pipeline are completely isolated from the annular sample to be tested, and the interference of residual liquid in the pipeline on the test is avoided.

The invention provides a device for dynamically testing liquid reaction molding shrinkage, wherein a flange plate can be welded at the lower end of a push rod of an electric cylinder; the servo motor is a motor with controllable rotating speed, the motor body is fixed on the flange plate by using bolts, and the shaft of the servo motor faces downwards; the lower end of the shaft of the servo motor is provided with threads and is connected with the upper end of the sample injection plunger through the threads of the coupler.

The invention provides a method for dynamically testing liquid reaction molding shrinkage.

The device and the method for dynamically testing the liquid reaction molding shrinkage have the following advantages:

1. the method comprises two metering steps, wherein a sample amount suitable for testing is measured through a pre-metering step, the precise metering step is carried out after the sample is heated to the reaction temperature, the sample is fully thermally expanded, and the temperature reaches a stable state, so that the heated volume of the sample can be accurately metered through testing, and errors caused by thermal expansion factors are completely eliminated in the dynamic acquisition shrinkage deformation process.

2. In the dynamic collection shrinkage deformation process, the sample injection plunger is pressed to the lowest position to completely press the pipeline for inputting the sample, so that the interference of the curing shrinkage of the resin liquid remaining in the pipeline to the test result can be avoided in the test process.

3. In the present invention, the relative rotation between the inside and the outside of the sample is applied, so that the shear action is applied to the sample during the solidification of the sample, and the molecular orientation is increased under the shear condition, so that the crystallinity is increased and the shrinkage is increased. The present invention has the ability to study the shear effect on sample shrinkage.

Drawings

FIG. 1 is a schematic view of an apparatus for dynamically testing liquid reaction molding shrinkage in accordance with the present invention;

FIG. 2 is a front view of an apparatus for dynamically testing liquid reaction molded shrinkage of the present invention with the test chamber partially broken away (pre-test condition);

FIG. 3 is a front view of an apparatus for dynamically testing liquid reaction molding shrinkage of the present invention with the test chamber partially broken away (pre-metered and heated);

FIG. 4 is a front view of an apparatus for dynamically testing liquid reaction molding shrinkage of the present invention with the test chamber partially broken away (metering state);

FIG. 5 is a front view of an apparatus for dynamically testing liquid reaction molded shrinkage of the present invention with the test chamber partially broken away (metered and tested);

FIG. 6 is a front view of an apparatus for dynamically testing liquid reaction molding shrinkage according to the present invention, wherein a flange is welded to a lower end of a push rod of an electric cylinder, and a motor body is fixed to the flange.

In the figure: the method comprises the following steps of 1-base, 2-test chamber fixing base, 3-test chamber, 4-annular plunger, 5-cylinder, 9-sample inlet plunger, 10-electric cylinder fixing base, 11-electric cylinder, 12-coupler, 13-displacement sensor, 14-electric heater, 15-sample inlet valve, 16-sample to be tested, 17-flange, 18-servo motor, L1-displacement of upward movement of sample inlet plunger in the pre-measurement step, L2-displacement of upward movement of annular plunger after measurement, and displacement of annular plunger generated by delta L-sample contraction.

Detailed Description

The invention provides a device for dynamically testing liquid reaction molding shrinkage, as shown in figures 1, 2, 3, 4 and 5, the module mainly comprises: the device comprises a base 1, a test cavity fixing seat 2, a test cavity 3, an annular plunger 4, a cylinder 5, a sample injection plunger 9, an electric cylinder fixing seat 10, an electric cylinder 11, a coupler 12, a displacement sensor 13, an electric heater 14, a sample injection valve 15 and a sample to be tested 16. Wherein, the base 1 is a round thick rigid flat plate and is arranged on the surface for placing the instrument; the testing cavity fixing seat 2 is a metal cylinder with an upright axis, the lower part of the cylinder is provided with four supporting legs, the center of the upper surface is provided with an internal thread blind hole, the bottom surface of the blind hole is a plane, the center is provided with a tiny through hole, the four supporting legs of the testing cavity fixing seat 2 are welded and connected with the base 1, and the testing cavity fixing seat 2 is coaxial with the base 1; the testing cavity 3 is a round pipe with a smooth inner surface, the lower part of the round pipe is provided with an external thread, the testing cavity 3 is connected with the testing cavity fixing seat 2 through the thread, and the thread is fully sealed by sealant; the annular plunger 4 is a pipe with smooth inner and outer surfaces, the pipe is vertically arranged, the upper end of the annular plunger is connected with a flange with a larger diameter, the flange is provided with four threaded holes along the circumference, the outer surface of the lower end of the pipe is precisely matched with the inner surface of the testing cavity 3, and the annular plunger can freely slide up and down while ensuring sealing; the four air cylinders 5 are four double-acting air cylinders which can provide tension or pressure after being inflated, the air cylinders 5 are uniformly arranged on the upper surface of the base 1 along the circumference, the bottom surface of the cylinder body is connected with the base 1 through threads, and an air cylinder rod of each air cylinder 5 is connected with a threaded hole in a flange of the annular plunger 4 through threads on the top of the air cylinder rod; the sample injection plunger 9 is a cylinder with a smooth outer surface, the outer surface of the lower end of the sample injection plunger 9 is precisely matched with the inner surface of the annular plunger 4 tube, the sample injection plunger can freely slide up and down while the sealing is ensured, and the upper end of the sample injection plunger 9 is provided with an external thread; the electric cylinder fixing seat 10 is a thicker rigid circular plate, a larger hole is formed in the middle of the circular plate, four support legs are uniformly distributed on the lower surface of the circular plate along the circumference, and the electric cylinder fixing seat 10 is fixed on the base 1 through the four support legs in a welding mode and is coaxial with the base; the electric cylinder 11 is an electric servo push rod capable of precisely controlling displacement, and is coaxially fixed on the electric cylinder fixing seat 10 through a bolt at the end part of the cylinder body, and the push rod of the electric cylinder faces downwards; the coupler 12 is a rigid short pipe, the inner hole of the coupler is provided with threads, and the push rod of the electric cylinder 11 is connected with the sample injection plunger 9 through the coupler 12 by the threads; the displacement sensor 13 is vertically fixed on the electric cylinder fixing seat 10, and the test probe can detect the relative displacement of the annular plunger 4 relative to the electric cylinder fixing seat 10; the electric heater 14 is an annular electric heating ring capable of accurately controlling temperature, and is wrapped on the outer surface of the test cavity 3, the sample injection valve 15 is a stop valve and is connected with a through hole of the test cavity fixing seat 2 through welding, and the lower end of the stop valve is connected with a pipeline for conveying liquid to be tested; the liquid 16 to be tested is a resin liquid to be tested, is input through a pipeline connected below the sample injection valve 15, and is filled in a cavity formed by the test cavity fixing seat 2, the test cavity 3, the annular plunger 4 and the sample injection plunger 9 during testing.

Before testing, as shown in fig. 2, a cylinder 5 retracts to enable an annular plunger 4 to move downwards to the bottommost end, a push rod of an electric cylinder 11 extends downwards to enable a sample injection plunger 9 to move to the lowest point, a sample injection valve 15 is closed, and a pipeline at the lower part of the sample injection valve 15 is filled with liquid to be tested with certain pressure; the first step of the test is a pre-measurement, as shown in fig. 3, in this step, the sample injection valve 15 is opened, the push rod of the electric cylinder 11 moves upward by a displacement L1 through servo control, and then the sample injection plunger 9 is driven to move upward by a displacement L1, the sample 16 to be tested enters the cylindrical cavity formed by the upward movement of the plunger 9 due to the self-pressure, in this step, the volume of the sample 16 to be tested is primarily controlled by controlling the displacement L1, in this step, the cylinder 5 is locked or outputs a large enough pulling force, so that the annular plunger 4 is kept at the lowest position; the second step of the test is preheating, in which the electric heater 14 is used to slowly heat the sample 16 to be tested to the temperature required for solidification, and in this step, the heating rate can be controlled to make the temperature rise process of the sample 16 to be tested consistent with the temperature in the injection machine barrel under the production condition so as to better reflect the real production process; the third step of the test is metering, as shown in fig. 4, in this step, the sampling valves 15 are closed, the air cylinders 5 respectively output a downward force F by controlling the air pressure, the annular plungers 4 are subjected to a downward total force fmot equal to 4 · F, at the same time, the push rods of the electric cylinders 11 push the sampling plungers 9 to slowly press downward, the sampling plungers 9 press downward to press the samples 16 to be tested below into the annular cavities around the sampling plungers 9 and push the annular plungers 4 upward, finally, as shown in fig. 5, the sampling plungers 9 press downward to the bottom end, all the samples 16 to be tested are pressed into the annular cavities around the sampling plungers 9, the upward displacement L2 of the annular plungers 4 can be accurately measured by the displacement sensor 13, and then the total volume vtot equal to L2 · S after the samples are heated, where S is the cross-sectional area of the annular cross-section, in this step, because the downward pressure of the annular plunger 4 is constant as F total, the pressure of a sample below is constant as P ═ F total/S, wherein S is the sectional area of the annular section, the downward pressure F total of the annular plunger 4 can be controlled in the step, so that the pressure P of the sample is equal to the pressure of a mold filling process in the real production process, and the downward pressing speed of the sample injection plunger 9 is controlled to control the shearing rate of the liquid 16 to be measured during flowing to be equal to the shearing rate of the liquid in the mold filling process of the liquid reaction molding forming, so that the real production process can be better reflected; the fourth step of the test is a test, as shown in fig. 5, in which the downward pressure of the annular plunger 4 is maintained at fsotai, and the pressure of the lower sample is constant at P ═ fsotai/S, at which time the data of the displacement sensor are collected in real time, at this time, because the sample 16 to be tested has a curing reaction at the testing temperature, the volume shrinks, and the size delta V of the volume shrinkage can be obtained by measuring the downward displacement delta L of the annular plunger 4, further, the curing shrinkage was determined: the delta V/V total is obtained by real-time dynamic data acquisition of the displacement sensor, and a function curve of the shrinkage rate of the sample 16 to be measured to time can be obtained, in this step, the sampling plunger 9 is located at the lowest point, and the sampling valve 15 and the related sample conveying pipeline are completely isolated from the annular sample 16 to be tested, so that the interference of residual liquid in the pipeline to the test is avoided.

The invention provides a device for dynamically testing liquid reaction molding shrinkage, as shown in fig. 6, a flange 17 can be welded at the lower end of a push rod of an electric cylinder 11; the servo motor 18 is a motor with controllable rotating speed, the motor body is fixed on the flange 17 by bolts, and the shaft of the servo motor 18 faces downwards; the lower end of the shaft of the servo motor 18 is provided with threads and is connected with the upper end of the sample injection plunger 9 through the threads of the coupler 12.

The invention provides a method for dynamically testing liquid reaction molding shrinkage, as shown in figure 6, in the testing process, a servo motor 18 rotates to drive a sample injection plunger 9 to rotate, so that the inner wall and the outer wall of a sample 16 to be tested rotate relatively, the shearing orientation of a molecular chain in the sample curing process can be controlled by controlling the time and the speed of the relative rotation, and the action rule of the sheared force on the shrinkage performance of the sample is further researched.