CN101712197B - Visual polymer micro-extrusion mold - Google Patents

Abstract

The invention discloses a visual polymer micro-extrusion mold and belongs to the technical field of polymer micro-extrusion molds. The visual polymer micro-extrusion mold is characterized in that the visual mold consists of a connecting pipe, a heating ring, a handpiece body, an adjusting bolt, a positioning pin, a baffle, a fastening bolt, a visual neck ring mold, a pressure/temperature sensor, a core rod, a gasket, a temperature sensor, a ventilating bolt, a support plate, a spure spreader and a flange. The spure spreader, the core rod and the neck ring mold with different structural parameters are respectively exchanged according to the need; coaxiality and clearance between the core rod and the visual neck ring mold are adjusted by the method of fixing the visual neck ring mold and adjusting the core rod; the visual neck ring mold is used for observing the flow state in the micro-extrusion mold of polymer melt; the pressure/temperature sensor is used for measuring pressure and temperature of straight section of the polymer melt; and the heating ring and the temperature sensor are used for controlling temperature of the micro-extrusion mold. The visual polymer micro-extrusion mold obtains flow distribution, flow characteristics and wall slip velocity of the polymer melt in the flow channel by the visual neck ring mold.

Description

A visualized polymer micro-extrusion die

technical field

The invention belongs to the technical field of polymer micro-extrusion dies, and relates to a visualized micro-extrusion die for observing the flow field distribution and wall sliding velocity of polymer melt in a micro flow channel.

Background technique

The flow process of polymer melt in the micro-channel of extrusion die has always been a key issue in the research of die design and polymer rheology. Traditional research methods can only infer the flow process of polymer melt in micro-channels through input and output parameters, such as temperature, viscosity, pressure, etc., and cannot directly describe the real flow behavior of polymers in the channel. The guiding role of the mold structure design is limited.

Micro-extrusion die is the key equipment in the whole micro-extrusion molding process of plastic melt. At present, when designing micro-extrusion dies, due to the incomplete rheological theory of polymers under the micro-scale effect, it is impossible to accurately describe the flow behavior of polymer melt in the flow channel of micro-extrusion dies, so the design of micro-extrusion dies is very complicated. Much depends on "trial and error". This method requires continuous mold testing and mold repair, which is time-consuming and labor-intensive, and the design quality is not high at the same time. According to statistics, the time for mold testing and mold repairing accounts for 30% to 40% of the entire design and manufacturing cycle of micro-extrusion molds, which causes a substantial increase in mold costs and affects the further development of micro-extrusion molds. Mold visualization technology is one of the most effective technical means to uncover the black box of the melt flow state in the mold. At present, mold visualization technology has become a research hotspot in the field of molds at home and abroad, mainly focusing on injection mold visualization technology, and has achieved significant research progress, but there is no report on the research on polymer micro-extrusion mold visualization technology at home and abroad. .

Contents of the invention

The technical problem to be solved by the present invention is to provide a visualized polymer micro-extrusion die, which is used to directly observe the flow field distribution and wall slip velocity in the process of polymer melt micro-extrusion. The observed results can improve the polymer rheology Theories directly guide the design of polymer micro-extrusion dies.

Technical scheme of the present invention is:

A visualized polymer micro-extrusion die, mainly composed of connecting pipe, heating ring, machine head body, adjusting bolt, positioning pin, baffle plate, fastening bolt, visualized die, pressure/temperature sensor, mandrel, gasket, temperature It consists of sensor, vent bolt, support plate, diverter cone and flange. The head body is connected to the outlet of the extruder through connecting pipes and flanges. The splitter cone and mandrel are respectively fixed on both sides of the support plate. The adjustment bolts and ventilation bolts are in contact with the support plate through the bolt holes on the head body. , baffle and fastening bolts fix the visualization die on the head body, the temperature sensor and heating ring are fixed on the connecting pipe, the head body and the outside of the visualization die, and the pressure/temperature sensor is installed on the straight section of the die Inside the small hole.

The mold can be replaced with splitter cones, mandrels and dies with different structural parameters according to the needs of research.

The molten polymer melt enters the flow channel of the mold through the connecting pipe under the action of pressure, enters the flow channel under the action of the splitter cone, is compressed by the compression section, and finally extruded from the straight section. The heating ring and temperature sensor installed on the mold control the polymer melt to maintain a constant temperature during the extrusion process; the coaxiality and gap between the mandrel and the die are changed by adjusting the adjusting bolt, so that the polymer melt is extruded The distribution of the flow field in the exit process is more uniform; the visualization die made of quartz glass is used to photograph the flow process of the polymer melt inside the die; the pressure sensor installed in the straight section also has the function of measuring temperature, which is a Integrated pressure/temperature sensor with computer communication interface for measuring pressure and temperature of polymer melt during extrusion.

The effect and benefit of the present invention are: obtain the real flow state of the polymer melt in the micro flow channel of the micro-extrusion die by visualizing the die, observe the flow field distribution and wall slip velocity of the polymer, thereby perfecting the polymer rheology research and Micro-extrusion die design theory; according to the research needs to replace the splitter cone, mandrel and die with different structural parameters, the influence of different mold cavity structural parameters on the polymer flow field distribution and wall slip velocity can be studied; through the use of fixed visualization The method of adjusting the die and adjusting the mandrel can effectively avoid the disadvantages of directly adjusting the visual die that is easy to break. The invention can directly guide the design of polymer micro-extrusion dies.

Description of drawings

The accompanying drawing is a structural schematic diagram of a visualized polymer micro-extrusion die.

In the figure: 1 connecting pipe; 2A heating ring; 3B heating ring; 4 head body; 5 adjusting bolts;

6 positioning pin; 7C heating ring; 8D heating ring; 9 baffle; 10 fastening bolt; 11E heating ring; 12 visual die; 13 pressure/temperature sensor; ; 18 ventilation bolts; 19 support plate; 20C temperature sensor; 21 split cone;

22D temperature sensor; 23 flange.

Detailed ways

Specific embodiments of the present invention will be described in detail below in conjunction with technical solutions and accompanying drawings.

Use A heating ring 2, B heating ring 3, C heating ring 7, D heating ring 8, and E heating ring 11 to heat the mold so that the temperature of each area of the mold reaches the set value. The temperature in the extrusion process is kept constant by controlling the A temperature sensor 15, B temperature sensor 17, C temperature sensor 20, and D temperature sensor 22 installed on the connecting pipe 1, the nose body 4 and the visual die 12. Under the action of the extruder screw, the polymer melt flows into the head body 4 from the connecting pipe 1, enters the flow channel through the splitter cone 21, and then under the joint action of the mandrel 14 and the visual die 12, the melt cross section The shape is gradually compressed to meet the design requirements, and is extruded from the exit of the visible die 12 . Adjust the adjusting bolt 5 to make the extrusion process smooth and even. The temperature and pressure during steady state extrusion are measured by the pressure/temperature sensor 13 installed on the straight section of the visualization die 12; at the same time, a high-speed camera is used to capture the flow state of the melt in the visualization die 12.

Observation of the melt flow process in the extrusion die of thermoplastic polyurethane (TPU) micro-intervention catheter.

Steps:

Step 1. Use a drying oven to dry the TPU at a certain temperature to remove moisture;

Step 2. Start the extruder, heat each section of the extruder and each area of the mold to the set temperature in stages, and keep it warm for a period of time;

Step 3. Stir the dried TPU plastic particles and tracer particles evenly, then pour them into the barrel, set the screw speed, and extrude;

Step 4. According to the cross-sectional shape and uniform wall thickness of the extruded product, adjust the adjusting bolt to change the coaxiality and gap between the mandrel and the die, so that the extrusion process is uniform and stable;

Step 5. Connect the microscope lens to the high-speed camera, adjust the light intensity of the shooting field, and shoot the flow state of the polymer melt in the tiny flow channel, and the pressure/temperature sensor records the pressure and temperature of the melt;

Step 6. Obtain the flow field distribution, rheological properties and wall slip velocity of the polymer melt in the micro-extrusion die through data processing and analysis;

Step 7. Set new extrusion process parameters, or replace splitter cones, mandrels, and visual dies with different structural parameters, and repeat steps 2 to 6 to obtain the influence of the micro-extrusion channel structure on the melt flow process. To guide the design of polymer microextrusion dies.

Claims (1)

1. a visual polymer micro-extrusion mold comprises tube connector (1), heating collar, handpiece body (4), adjustment bolt (5), alignment pin (6), baffle plate (9), fastening bolt (10), visual neck ring mold (12), pressure (13), plug (14), temperature sensor, packing ring (16), ventilation bolt (18), gripper shoe (19), divides flow cone (21), flange (23); Heating collar comprises A heating collar (2), B heating collar (3), C heating collar (7), D heating collar (8) and E heating collar (11); Temperature sensor comprises A temperature sensor (15), B temperature sensor (17), C temperature sensor (20), D temperature sensor (22); It is characterized in that: handpiece body links to each other with outlet of extruder with flange (23) by tube connector (1), divide flow cone (21) and plug (14) to be separately fixed at gripper shoe (19) both sides, adjustment bolt (5) and ventilation bolt (18) contact with gripper shoe (19) by the bolt hole on the handpiece body (4), utilize packing ring (16), baffle plate (9) and fastening bolt (10) are fixed on visual neck ring mold on the handpiece body, temperature sensor and heating collar are fixed on tube connector, the outside of handpiece body and visual neck ring mold (12), pressure (13) are installed in the aperture of flat segments of visual neck ring mold; Change branch flow cone (21), plug (14) and the visual neck ring mold (12) of different structure parameter as required; Use velocity field and the wall slippage speed of visual neck ring mold (12) observation polymer melt in the micro-extrusion mold runner of quartz glass material; Adopt the fixedly method of visual neck ring mold (12), adjustment plug (14), regulate axiality and gap between plug and the visual neck ring mold; The flat segments pressure of visual neck ring mold (12) is measured the pressure and temperature of polymer melt in little extrusion; Heating collar and temperature sensor control polymer melt keep the temperature of setting in little extrusion.

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