A capillary rheometer

Abstract

The present invention discloses a capillary rheometer, including a base and a shell. A heating body bracket is provided on the upper part of the base, a heating body rotating table is provided on the heating body bracket, a barrel is provided on the heating body rotating table, a heating sleeve is provided on the outside of the barrel, a capillary die is connected to the bottom of the barrel, a plunger is provided in the barrel, a pressure rod is provided directly above the plunger, a lifting frame is fixedly connected to the pressure rod above, the lifting frame is connected to a pressure rod constant pressure force mechanism, the pressure rod constant pressure force mechanism is a lever force structure, and the pressure rod constant pressure force mechanism is provided with an optical encoder, which can record the speed of the plunger movement in real time and with high precision. The pressure rod constant pressure force mechanism of the present invention is a lever force structure, and the pressure transmission is stable, and the movement speed of the melt can be recorded in real time and with high precision, so as to conveniently calculate the rheological properties of the measured material.

Description

Technical Field

[0001] The invention belongs to the technical field of rheometers, and in particular relates to a pressure-type capillary rheometer. Background Art

[0002] Capillary rheometer is one of the most mature and widely used rheological measuring instruments. Its main advantages are simple operation, accurate measurement and wide measurement range. Pressure capillary rheometers can be divided into two categories: one is constant pressure capillary rheometer, such as melt indexer; the other is gravity capillary rheometer, such as Ubbelohde viscometer. Constant pressure capillary rheometer can not only measure the relationship between shear stress and shear rate of polymer melt in capillary, but also study the elasticity and unstable flow (including melt fracture) of melt by changing the aspect ratio of capillary under constant stress according to the diameter and appearance of extrudate, so as to predict the processing behavior of polymer, which is used as the basis for selecting compound formula, seeking the best molding process conditions and controlling product quality. In addition, it can also provide basic data for the auxiliary design of polymer processing machinery and molding molds, and can be used as an auxiliary means for the characterization of polymer macromolecular structure.

[0003] In the prior art, when a constant pressure is applied to a pressure-type capillary rheometer, a pressure block or a weight is set on the top of the pressure rod, which is often inconvenient to operate. When a relatively large constant pressure needs to be applied, the pressure block or the weight is set relatively large, which is not conducive to operation and even has certain safety hazards. Summary of the invention

[0004] Aiming at the deficiencies of the prior art, the present invention improves the constant pressure component of a pressure-type capillary rheometer and provides a capillary rheometer which is easy to operate and use.

[0005] The technical solution adopted by the present invention is: a capillary rheometer, including a base and a shell, a heating body bracket is arranged on the upper part of the base, a heating body rotating table is arranged on the heating body bracket, a barrel is arranged on the heating body rotating table, a heating sleeve is arranged on the outside of the barrel, a capillary die is connected to the bottom of the barrel, a plunger is arranged in the barrel, a pressure rod is arranged directly above the plunger, a lifting frame is fixedly connected to the top of the pressure rod, the lifting frame is provided with guide column holes on both sides, the guide column holes are nested on the guide columns, the lifting frame moves up and down on the guide columns, the lower end of the guide column is fixed on the fixed beam, the fixed beam is fixedly connected to the shell, the upper end of the guide column is fixedly connected to the shell, the lifting frame is connected to the pressure rod constant pressure force mechanism, and the pressure rod constant pressure force mechanism is a lever force structure.

[0006] The pressure rod constant pressure force mechanism includes a lifting frame connecting rope, a lifting frame connecting rope fixing point is arranged on the lifting frame, the other end of the lifting frame connecting rope is connected to the lifting frame rotating wheel, the lifting frame rotating wheel is arranged at one end of the transmission rod, and a weight rotating wheel is arranged at the other end of the transmission rod. An optical encoder is arranged at the end of the transmission rod on one side of the weight rotating wheel. The optical encoder records the rotation speed of the transmission rod in real time and thus records the movement speed of the plunger in the vertical direction in real time. The weight rotating wheel is connected to the weight through the weight connecting rope, and the diameter of the weight rotating wheel is larger than that of the lifting frame rotating wheel.

[0007] There are two guide posts, and there are also two guide post holes of the lifting frame corresponding to the guide posts.

[0008] The lifting frame has an opening in the middle, the height of the opening is greater than the lifting height of the lifting frame, and the fixing point of the connecting rope of the lifting frame is arranged at the middle position of the top of the opening.

[0009] The diameter of the weight wheel is 5 times the diameter of the lifting frame wheel.

[0010] The pressure rod and plunger are cylindrical in shape, the center lines of the cylinders of the pressure rod and plunger are on a vertical line, and the fixing point of the lifting frame connecting rope is also arranged on the extension line of the center lines of the cylinders of the pressure rod and plunger.

[0011] A cylinder is also fixedly mounted on the fixed beam, and the cylinder is connected to the lifting frame, and the lifting frame is lifted up under the action of the cylinder.

[0012] A travel switch is arranged on the guide column, and the travel switch controls the position of the upper limit of the lifting frame.

[0013] The base is provided with a power switch, a power indicator light, a "cylinder top" button, and a "cylinder return" button. The power switch controls the heating sleeve and the cylinder at the same time. When the "cylinder top" button is activated, the lifting frame is lifted up under the action of the cylinder. When the "cylinder return" button is activated, the lifting frame descends under the action of gravity and the tension of the lifting frame connecting rope.

[0014] The advantages or principles of the present invention are described below.

[0015] 1. The present invention adopts the constant pressure force mechanism of the pressure rod as a lever force structure, and the pressure transmission is stable. The preferred diameter of the weight wheel is 2-15 times the diameter of the lifting frame wheel. The use of small-mass weights can achieve a large constant pressure on the pressure rod.

[0016] 2. The plunger is connected to the weight (heavy object) through the lifting frame, the lifting frame wheel, the transmission shaft and the weight wheel. The lifting frame moves vertically up and down on the guide column, so that the force of the plunger on the pressure rod remains in the vertical direction, and the pressure measurement is accurate.

[0017] 3. The present invention converts the constant pressure that needs to be applied to the plunger into a constant force given by the weight to the weight wheel through the pressure rod constant pressure force application mechanism, and converts the vertical movement into the circumferential movement of the weight wheel. The high-precision optical encoder records the circumferential movement speed of the transmission rod in real time, thereby recording the vertical movement speed of the plunger in real time and with high precision. Under constant pressure, the running speed of the molten material in the die is recorded in real time, thereby obtaining high-precision shear stress, viscosity and other parameters of the molten material, and the measurement result is accurate and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0019] Figure 2 It is a left-side structural schematic diagram of the lever force applying mechanism of the present invention.

[0020] Figure 3 It is a schematic diagram of the three-dimensional structure of the lever force applying mechanism of the present invention.

[0021] Figure 4 It is a schematic diagram of the structure of the heating sleeve of the present invention.

[0022] In the figure: 1-base, 2-heating body rotating table, 3-heating body bracket, 4-plunger, 5-pressure rod, 6-fixed beam, 7-guide column, 8-lifting frame, 9-cylinder, 10-transmission rod, 11-weight wheel, 12-weight, 13-weight connecting rope, 14-lifting frame connecting rope, 15-lifting frame wheel, 16-lifting frame connecting rope fixing point, 17-travel switch, 18-housing, 19-capillary die, 20-fixing nut, 21-heating sleeve, 22-barrel, 23-optical encoder. DETAILED DESCRIPTION

[0023] In order to more clearly understand the technical solution of the present invention, the present invention is further described below in conjunction with the accompanying drawings.

[0024] like Figures 1 to 4As shown in the figure, a capillary rheometer comprises a base 1 and a shell 18, wherein a heating body bracket 3 is arranged on the upper part of the base 1, a heating body rotating table 2 is arranged on the heating body bracket 3, a barrel 22 is arranged on the heating body rotating table 2, a heating sleeve 21 is arranged outside the barrel 21, a capillary die 19 is connected to the bottom of the barrel 22, a fixing nut 20 is arranged at the lower part of the capillary die 19, the fixing nut 20 is connected to the barrel 22, and a plunger 4 is arranged inside the barrel 22. A pressure rod 5 is arranged directly above the plunger 4, and a lifting frame 8 is fixedly connected above the pressure rod 5. The lifting frame 8 is provided with guide column holes on both sides, and the guide column holes are nested on the guide columns 7. The lifting frame 8 moves up and down on the guide columns 7. The lower end of the guide column 7 is fixed on the fixed beam 6, and the fixed beam 6 is fixedly connected to the shell 18. The upper end of the guide column 7 is fixedly connected to the shell 18. The lifting frame 8 is connected to a pressure rod constant pressure force mechanism, and the pressure rod constant pressure force mechanism is a lever force structure.

[0025] The constant pressure force mechanism of the pressure rod includes a lifting frame connecting rope 14, a lifting frame connecting rope fixing point 16 is set on the lifting frame 7, the other end of the lifting frame connecting rope 14 is connected to the lifting frame rotating wheel 15, the lifting frame rotating wheel 15 is set at one end of the transmission rod 10, and the other end of the transmission rod 10 is set with a weight rotating wheel 11, and the transmission rod 10 is provided with an optical encoder 23 at the end located on one side of the weight rotating wheel 11. The optical encoder 23 uses a high-precision optical encoder. The optical encoder 23 records the speed of the transmission rod 10 in real time and thus records the vertical movement speed of the plunger 4 in real time. The weight rotating wheel 11 is connected to the weight 12 through the weight connecting rope 13. The gravity of the weight can be selected according to the test requirements of the capillary rheometer, and the range of 0.5kg, 1kg, 2kg, 5kg, etc. can be selected. The diameter of the weight rotating wheel 11 is larger than that of the lifting frame rotating wheel 15. The diameter of the weight rotating wheel 11 described in the embodiment is 5 times the diameter of the lifting frame rotating wheel 15. There are two guide posts 7, and there are also two guide post holes for the lifting frame corresponding to the guide posts 7. The lifting frame 8 is open in the middle, and the height of the opening is greater than the lifting height of the lifting frame. The lifting frame connecting rope fixing point 16 is set at the top middle position of the opening. The plunger 4 and the pressure rod 5 are cylindrical in shape, and the center lines of the cylinders of the plunger 4 and the pressure rod 5 are on a vertical line. The lifting frame connecting rope fixing point 16 is also set on the extension line of the center lines of the cylinders of the pressure rod 5 and the plunger 4. The fixed beam 6 is also fixedly mounted with a cylinder 9, and the cylinder 9 is connected to the lifting frame 8, and the lifting frame 8 is lifted up by the action of the cylinder.

[0026] The guide column 7 is provided with a travel switch 17, and the travel switch 17 controls the upper limit position of the lifting frame 8. The base 1 is provided with a power switch, a power indicator light, a "cylinder top" button, and a "cylinder return" button. The power switch controls whether the heating sleeve is heated or not. When the "cylinder top" button is activated, the lifting frame is lifted up under the action of the cylinder. When the "cylinder return" button is activated, the lifting frame descends under the action of gravity and the tension of the lifting frame connecting rope.

[0027] The working principle of the capillary rheometer of the present invention is: first, add an appropriate amount of material into the barrel 22, plug the barrel 22 with the plunger 5, heat the heating sleeve 21 to melt the material, press the "cylinder top" button, the cylinder 9 lifts the lifting frame 8, and the weight of the required weight 12 is connected to the weight connecting rope 13, press the "cylinder return" button, the cylinder 9 is loosened, and under the gravity of the lifting frame 8 and the weight 12, the lifting frame 8 descends. At this time, the force application point of the lifting frame 8 is only at the pressure rod 4. It should be noted that the force applied by the weight wheel 11 on the transmission rod 10 is transmitted to the lifting frame wheel 15, forming a lever structure with different force arms, so the weight of the weight is amplified. The constant pressure to be applied to the plunger 4 is converted into a constant force given to the weight wheel 11 by the pressure rod constant pressure force mechanism, and the vertical movement is converted into the circumferential movement of the weight wheel 11. The high-precision optical encoder 23 records the circumferential movement speed of the transmission rod 10 in real time, thereby recording the vertical movement speed of the plunger 4 in real time and with high precision. The elasticity and unstable flow (including melt fracture) of the melt are studied through a capillary die under constant stress, and the movement speed of the melt is recorded in real time, thereby predicting the processing behavior of the polymer, which serves as a basis for selecting the compound formula, seeking the best molding process conditions and controlling product quality.

[0028] The above are only specific embodiments of the present invention, which are only used to illustrate the present invention and are not limited to the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope limited by the appended claims of the present application.

Claims

1. A capillary rheometer, comprising a base and a housing, wherein a heating body bracket is provided on the upper part of the base, a heating body rotating platform is provided on the heating body bracket, a barrel is provided on the heating body rotating platform, a heating sleeve is provided on the outside of the barrel, a capillary die is connected to the bottom of the barrel, a plunger is provided in the barrel, and a pressure rod is provided just above the plunger, characterized in that: The pressure rod is fixedly connected to the lifting frame on the top, and the lifting frame is provided with guide column holes on both sides, and the guide column holes are nested on the guide columns. The lifting frame moves up and down on the guide columns, and the lower end of the guide column is fixed on the fixed beam, and the fixed beam is fixedly connected to the shell, and the upper end of the guide column is fixedly connected to the shell. The lifting frame is connected to the pressure rod constant pressure force mechanism, and the pressure rod constant pressure force mechanism is a lever force structure, and the pressure rod constant pressure force mechanism includes a lifting frame connecting rope, and a lifting frame connecting rope fixing point is provided on the lifting frame, and the other end of the lifting frame connecting rope The end is connected to the lifting frame wheel, the lifting frame wheel is arranged at one end of the transmission rod, and the other end of the transmission rod is provided with a weight wheel. The transmission rod is provided with an optical encoder at the end located on one side of the weight wheel. The optical encoder records the rotation speed of the transmission rod in real time and thus records the vertical movement speed of the plunger in real time. The weight wheel is connected to the weight through a weight connecting rope. The diameter of the weight wheel is larger than that of the lifting frame wheel. A cylinder is also fixedly installed on the fixed beam. The cylinder is connected to the lifting frame, and the lifting frame is lifted up under the action of the cylinder.

2. The capillary rheometer according to claim 1, characterized in that: There are two guide posts, and there are also two guide post holes of the lifting frame corresponding to the guide posts.

3. The capillary rheometer according to claim 1, characterized in that: The lifting frame has an opening in the middle, the height of the opening is greater than the lifting height of the lifting frame, and the fixing point of the connecting rope of the lifting frame is arranged at the middle position of the top of the opening.

4. The capillary rheometer according to claim 1, characterized in that: The diameter of the weight wheel is 2-15 times the diameter of the lifting frame wheel.

5. The capillary rheometer according to claim 1, characterized in that: The plunger and the pressure rod are cylindrical in shape, the center lines of the cylinders of the plunger and the pressure rod are on a vertical line, and the fixing point of the lifting frame connecting rope is also arranged on the extension line of the center lines of the cylinders of the pressure rod and the plunger.

6. The capillary rheometer according to claim 1, characterized in that: A travel switch is arranged on the guide column, and the travel switch controls the position of the upper limit of the lifting frame.

7. The capillary rheometer according to claim 1, characterized in that: The base is provided with a power switch, a power indicator light, a "cylinder top" button, and a "cylinder return" button. The power switch controls the heating sleeve and the cylinder at the same time. When the "cylinder top" button is activated, the lifting frame is lifted up under the action of the cylinder. When the "cylinder return" button is activated, the lifting frame descends under the action of gravity and the tension of the lifting frame connecting rope.

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