Ultrasonic-assisted micro injection molding device

Abstract

The invention relates to the field of injection molding, in particular to an ultrasonic-assisted micro injection molding device. An ultrasonic-assisted micro injection molding device comprises a rack, a power unit connected to the rack and the like, the power unit is connected with a movable mold, the rack is fixedly connected with a fixed mold, the fixed mold and the movable mold are closed to form a cavity for injection molding, and the power unit is used for driving the movable mold to move and enabling the movable mold to be in contact fit with the fixed mold. The rack is connected with a material conveying unit, the material conveying unit is connected with an ultrasonic sleeve, and the rack is provided with an ultrasonic generator. Ultrasonic assistance is applied to the material conveying pipe through the ultrasonic sleeve, ultrasonic waves penetrate through the material conveying pipe to act on molten materials in an indirect energy transfer mode, the molten materials are uniform in component through the ultrasonic waves, plastic particles are fully molten in cooperation with the primary heating sleeve and the secondary heating sleeve, the strength and surface smoothness of a formed part are improved, and the product quality is improved. The plasticizing quality is ensured.

Description

Technical Field

[0001] This invention relates to the field of injection molding, and more particularly to an ultrasonic-assisted micro-injection molding device. Background Technology

[0002] Micro-injection molding technology is considered the most important manufacturing method for microstructure fabrication. It features simple manufacturing process, low production cost, and ease of mass production. It can fully fill the mold core channels of microstructure features and achieve good injection molding results.

[0003] Currently, the patent application CN102166813A (An Ultrasonic Assisted Micro-Injection Molding Mold) mentions that by applying ultrasonic waves to the moving mold, the fluidity of the melt is increased, thereby enabling the melt to have a good filling effect in the micro-mold cavity and improving the injection molding quality. However, it does not consider that during the process of melting plastic particles into a melt, the plastic particles are generally conveyed by a screw and heated and melted during the conveying process. If the conveying speed and heating power are not matched, there will be unmelted plastic particles in the melt. In ordinary injection molding, the unmelted part does not affect the molding. However, for micro-mold injection molding, the unmelted plastic particles entering the micro-mold cavity are prone to clogging the flow channel of the cavity, thereby affecting the full filling of the cavity by the melt and thus affecting the final injection molding quality. Summary of the Invention

[0004] In order to overcome the shortcomings of existing technologies where plastic particles are not fully melted, which easily clogs the flow channels of the mold cavity, thus affecting the full filling of the mold cavity by the melt and consequently affecting the final injection molding quality, this invention provides an ultrasonic-assisted micro-injection molding device.

[0005] The technical implementation of the present invention is as follows: an ultrasonic-assisted micro-injection molding device, comprising a frame and a power unit connected to the frame, the power unit being connected to a moving mold, the frame being fixedly connected to a fixed mold, the power unit being used to drive the moving mold to move and to make the moving mold and the fixed mold contact and cooperate, the frame being connected to a material conveying unit, the material conveying unit being connected to an ultrasonic sleeve, the frame being mounted with an ultrasonic generator, the material conveying unit being connected to the fixed mold, the material conveying unit being used to inject molten plastic into the cavity formed by the moving mold and the fixed mold, the material conveying unit being connected to a plurality of amplitude transformers, all of which are elastically connected to the material conveying unit.

[0006] More preferably, the ultrasonic sleeve is provided with sound-absorbing cotton on the outside.

[0007] More preferably, the power unit includes a first servo motor, two first servo motors are mounted on the frame and distributed vertically, two lead screws are rotatably connected to the frame, each lead screw is fixedly connected to the output shaft of a first servo motor, two slide rods are fixedly connected to the frame, each slide rod corresponds to a lead screw, the fixed mold is screwed to all the lead screws, and the fixed mold is slidably connected to all the slide rods.

[0008] More preferably, the feeding unit includes a feeding pipe, which is fixedly connected to the frame. The feeding pipe is connected to a feeding hopper. A second servo motor is installed on the feeding pipe. A primary heating jacket is installed outside the feeding pipe. A secondary heating jacket is installed on the feeding pipe. The secondary heating jacket is located between the primary heating jacket and the ultrasonic sleeve. The temperature of the secondary heating jacket is higher than that of the primary heating jacket. A spiral shaft is rotatably connected to the feeding pipe. Spiral blades are fixedly connected to the outer ring surface of the spiral shaft. The spiral blades are rotatably connected to the inner wall of the feeding pipe. A tapered gate is provided at the left end of the feeding pipe. The gate is connected to the fixed mold. A heating assembly is connected to the outside of the feeding pipe. The heating assembly is used to melt the plastic granules. The feeding pipe is slidably connected to all the amplitude transformers.

[0009] More preferably, the helical blades are hollow.

[0010] More preferably, both the primary heating jacket and the secondary heating jacket are equipped with an electromagnetic induction heating module and a temperature sensor.

[0011] More preferably, it also includes a connecting sleeve, on the side of the spiral shaft away from the second servo motor, the connecting sleeve is rotatably connected to the connecting sleeve, a plurality of fixed sleeves are fixedly connected to the connecting sleeve, each fixed sleeve is rotatably connected to an amplitude transformer, each fixed sleeve is fixedly connected to a sealing sleeve, and each sealing sleeve is fixedly connected to an amplitude transformer.

[0012] More preferably, it also includes sealing plates and spring rods, with a sealing plate slidably connected to each of the amplitude rods, and a spring rod fixedly connected to each of the amplitude rods, all of the spring rods being connected to the feed pipe, and the feed pipe being fixedly connected to all the sealing plates.

[0013] More preferably, both the sealing sleeve and the sealing sheet are made of high-temperature resistant fluororubber.

[0014] More preferably, a shock-absorbing sleeve is provided outside the conveying pipe, the shock-absorbing sleeve is fixedly connected to all the spring rods, and the shock-absorbing sleeve is made of a porous material.

[0015] Compared with the prior art, the present invention has the following advantages: The present invention applies ultrasonic assistance to the feed pipe through an ultrasonic sleeve, and in the form of indirect energy transfer, the ultrasonic waves penetrate the feed pipe and act on the molten material, so that the ultrasonic waves make the composition of the molten material uniform, and work together with the primary heating sleeve and the secondary heating sleeve to fully melt the plastic particles, improve the strength and surface smoothness of the molded parts, and ensure the plasticizing quality.

[0016] By setting the spiral blades to a hollow structure, when the ultrasonic waves are transmitted to the spiral blades, the hollow structure inside the spiral blades forms a resonant cavity. This allows the ultrasonic waves to be transmitted outward after resonating through the spiral blades, making it easier for the plastic particles near the spiral axis to receive the energy of the ultrasonic waves, thereby melting the unmelted plastic particles in the molten material.

[0017] By placing sound-absorbing cotton on the outside of the ultrasonic sleeve, the sound-absorbing cotton can absorb the noise generated during the operation of the ultrasonic sleeve.

[0018] The vibration generated by the auger shaft is transmitted to the spring rod and the porous damping sleeve through the movement of the auger rod, thereby absorbing excessive vibration, ensuring the stability of the auger shaft, achieving injection stability, and ensuring injection molding quality. Attached Figure Description

[0019] Figure 1 This is a three-dimensional structural schematic diagram of the ultrasonic-assisted micro-injection molding device of the present invention; Figure 2 This is a side view of the ultrasonic-assisted micro-injection molding apparatus of the present invention; Figure 3 This is a schematic diagram of the internal structure of the material conveying pipe of the present invention; Figure 4 This is a schematic diagram of the installation position of the amplitude transformer bar according to the present invention; Figure 5 For the present invention Figure 4 Enlarged view of point A in the middle; Figure 6 For the present invention Figure 4 Enlarged view of point B in the middle.

[0020] The above-mentioned attached drawings include the following reference numerals: 1-frame, 2-first servo motor, 3-lead screw, 4-slide bar, 5-moving mold, 6-fixed mold, 7-feed pipe, 8-feed hopper, 9-second servo motor, 10-primary heating jacket, 11-secondary heating jacket, 12-ultrasonic sleeve, 13-ultrasonic generator, 14-spiral shaft, 15-spiral blade, 16-connecting sleeve, 17-fixed sleeve, 18-amplifier rod, 19-sealing sleeve, 20-sealing sheet, 21-spring rod, 701-gate, 702-shock-absorbing sleeve. Detailed Implementation

[0021] First, it should be noted that in different described embodiments, the same components are given the same reference numerals or the same component names. The disclosure contained throughout this specification can be applied semantically to the same components having the same reference numerals or the same component names. The location descriptions selected in the specification, such as upper, lower, lateral, etc., also refer to the directly described and illustrated figures and are semantically applied to the new location when the location changes.

[0022] Example 1: An ultrasonic-assisted micro-injection molding device, according to Figures 1-6 As shown, the system includes a frame 1 and a power unit connected to the frame 1. The power unit is connected to a moving mold 5. A fixed mold 6 is fixedly connected to the frame 1. After the fixed mold 6 and the moving mold 5 are closed, they form an injection cavity. A micro mold is detachably connected to the fixed mold 6 and the moving mold 5. The power unit is used to drive the moving mold 5 to move and make the moving mold 5 contact and cooperate with the fixed mold 6. A material conveying unit is connected to the frame 1. The material conveying unit is connected to an ultrasonic sleeve 12. An ultrasonic generator 13 is installed on the frame 1. The ultrasonic generator 13 is electrically connected to the ultrasonic sleeve 12. The ultrasonic sleeve 12 consists of a fixed cylinder, a transducer, and a waveguide rod. The transducer of the ultrasonic sleeve 12 is distributed in a ring array on the fixed cylinder. The waveguide rod of the ultrasonic sleeve 12 is in close contact with the material conveying unit. The material conveying unit is connected to the fixed mold 6. The material conveying unit is used to inject the plastic melt into the cavity formed by the moving mold 5 and the fixed mold 6. The material conveying unit is connected to six amplitude transformers 18 distributed in a ring array. All amplitude transformers 18 are elastically connected to the material conveying unit.

[0023] The ultrasonic sleeve 12 is equipped with sound-absorbing cotton on the outside.

[0024] The power unit includes a first servo motor 2, a lead screw 3, and a slide bar 4. Two first servo motors 2 are mounted on the frame 1, which is distributed vertically. Two lead screws 3 are rotatably connected to the frame 1, and each lead screw 3 is fixedly connected to the output shaft of a first servo motor 2. Two slide bars 4 are fixedly connected to the frame 1, and each slide bar 4 corresponds to a lead screw 3. The fixed mold 6 is screwed to all the lead screws 3 and slidably connected to all the slide bars 4.

[0025] The feeding unit includes a feeding pipe 7, a feeding hopper 8, a second servo motor 9, a primary heating jacket 10, a secondary heating jacket 11, a spiral shaft 14, and spiral blades 15. The feeding pipe 7 is fixedly connected to the right side of the frame 1, and the feeding hopper 8 is connected to the right side of the feeding pipe 7. The second servo motor 9 is installed at the right end of the feeding pipe 7. The primary heating jacket 10 is installed outside the feeding pipe 7. The secondary heating jacket 11 is installed on the feeding pipe 7. The secondary heating jacket 11 is located between the primary heating jacket 10 and the ultrasonic sleeve 12. The temperature of the secondary heating jacket 11 is higher than that of the primary heating jacket 10. The feeding pipe 7 is rotatably connected to the spiral shaft 14. The spiral blades 15 are fixedly connected to the outer ring surface of the spiral shaft 14. The spiral blades 15 are rotatably connected to the inner wall of the feeding pipe 7. The left end of the feeding pipe 7 is provided with a conical gate 701, which is connected to the fixed mold 6. A heating component is connected to the outside of the feeding pipe 7. The heating component is used to melt the plastic particles. The feeding pipe 7 is slidably connected to all the amplitude rods 18.

[0026] The spiral blade 15 is designed as a hollow structure to form a resonant cavity and amplify the ultrasonic effect.

[0027] Both the primary heating jacket 10 and the secondary heating jacket 11 are equipped with electromagnetic induction heating modules and temperature sensors.

[0028] The device is fixed on a stable workbench, and then the micro-molds are installed onto the moving mold 5 and the fixed mold 6 respectively. The detachable micro-mold design increases the device's versatility. The moving mold 5 and the fixed mold 6 have built-in temperature control structures. By controlling the temperature of the circulating water, the temperature of the moving mold 5 and the fixed mold 6 is controlled as the circulating water flows through them. First, the circulating water is heated, causing the temperature of the moving mold 5 and the fixed mold 6 to rise. This prevents the molten material from being trapped in the cavity formed after the moving mold 5 and the fixed mold 6 are closed. A sudden drop in temperature leads to poor flowability of the molten material, preventing it from filling the entire cavity and resulting in poor injection molding. To address this, two first servo motors 2 are activated, driving corresponding lead screws 3 to rotate. Simultaneously, the moving mold 5 moves to the right along the slide bar 4. The micro-mold on the moving mold 5 closes with the micro-mold on the fixed mold 6, forming the injection cavity. An external feeding device then feeds plastic granules into the conveying hopper 8, which enters the conveying pipe 7. Simultaneously, a second servo motor 9 is activated, driving the spiral shaft 14 and its related parts to rotate. This causes the spiral blades 15 to move the plastic granules to the left within the conveying pipe 7. The primary heating jacket 10 and the secondary heating jacket 11 are activated sequentially. The electromagnetic induction heating module in the primary heating jacket 10 programmatically heats the plastic granules, while the higher-temperature secondary heating jacket 11 melts the heated plastic, turning the granules into molten material. Temperature sensors in the primary and secondary heating jackets 10 and 11 monitor the temperature in real time, thus achieving multi-stage heating. The process achieves efficient material feeding. The molten material continues to move to the left under the drive of the spiral blade 15. After passing through the gate 701, the molten material is injected into the cavity formed by the moving mold 5 and the fixed mold 6. After the molten material fills the cavity, the pressure is maintained for a period of time. Cooling circulating water is introduced into the moving mold 5 and the fixed mold 6 to cool them down and further cool the cavity. Then, the two first servo motors 2 are started to separate the moving mold 5 and the fixed mold 6. The molded part can then be removed from the moving mold 5, thus completing the injection molding process.

[0029] Based on the above injection molding process, after the plastic granules are heated and melted by the primary heating jacket 10 and the secondary heating jacket 11, they form a molten material. The molten material is then conveyed by the spiral shaft 14 and spiral blades 15. Plastic granules closer to the inner wall of the conveying pipe 7 are more readily heated by the primary heating jacket 10 and the secondary heating jacket 11, thus melting and plasticizing first. Plastic granules closer to the spiral shaft 14 are melted and plasticized later. During the conveying process, the plastic granules are compressed, and some may not be fully melted and plasticized. The spiral blades 15 are designed as hollow structures. When ultrasonic waves are transmitted to the spiral blades 15, the hollow structure inside the spiral blades 15 forms a resonant cavity. This allows the ultrasonic waves to be transmitted outwards after resonance through the spiral blades 15, making it easier for the plastic granules closer to the spiral shaft 14 to receive the energy of the ultrasonic waves. The cavitation effect of the ultrasonic waves originates from the dynamic response of the cavitation nuclei in the sound field. When the ultrasonic waves propagate, they pass through the cavitation nuclei that are not fully melted... In the molten plastic granules, those that are not fully melted are more susceptible to the cavitation effect of ultrasound. The unmelted granules contain more tiny air bubbles than the fully melted material, causing their temperature to rise and eventually melting the unmelted granules in the molten material. At this point, the ultrasonic generator 13 is activated, controlling the transducers on the ultrasonic sleeve 12 to generate ultrasonic vibrations. The sound-absorbing cotton on the ultrasonic sleeve 12 reduces noise generation. The ultrasonic waves are then transmitted to the molten material in the feed pipe 7 via a waveguide rod. Through the ultrasonic sleeve 12 located outside the feed pipe 7, the ultrasound waves penetrate the feed pipe 7 and act on the molten material in an indirect energy transfer manner. Furthermore, the transducers are arranged in a ring array on the ultrasonic sleeve 12, allowing ultrasound to be applied to the molten material from different directions, thereby improving energy distribution. This results in uniform composition of the molten material, improved strength and surface finish of the molded parts, and ensured plasticizing quality.

[0030] Example 2: Based on Example 1, according to Figures 1-6 As shown, it also includes a connecting sleeve 16, a fixed sleeve 17, and a sealing sleeve 19. The connecting sleeve 16 is rotatably connected to the side of the spiral shaft 14 away from the second servo motor 9. Six fixed sleeves 17 arranged in a ring array are fixedly connected to the connecting sleeve 16. Each fixed sleeve 17 is rotatably connected to an amplitude transformer 18. Each fixed sleeve 17 is fixedly connected to a sealing sleeve 19. The middle part of each sealing sleeve 19 is fixedly connected to an amplitude transformer 18.

[0031] It also includes sealing plates 20 and spring rods 21. Each amplitude rod 18 has a sealing plate 20 slidably connected to it, and each amplitude rod 18 has a spring rod 21 fixedly connected to it. All spring rods 21 are connected to the feed pipe 7, and the feed pipe 7 is fixedly connected to all the sealing plates 20.

[0032] Both the sealing sleeve 19 and the sealing plate 20 are made of high-temperature resistant fluororubber.

[0033] A shock-absorbing sleeve 702 is installed outside the material conveying pipe 7. The shock-absorbing sleeve 702 is fixedly connected to all the spring rods 21. The shock-absorbing sleeve 702 is made of porous material.

[0034] Considering that adding an ultrasonic auxiliary mechanism to the existing injection molding process can easily cause excessive radial vibration of the rotating helical shaft 14 due to the vibration generated by ultrasound, which may lead to increased wear on the helical blades 15 and the feed tube 7, potentially interfering with the stability of material feeding and the accuracy of metering, resulting in unstable injection volume, it is necessary to dampen the end of the helical shaft 14. When the ultrasonic sleeve 12 applies ultrasonic influence to the feed tube 7, the helical shaft 14 will also generate radial vibration. Therefore, a connecting sleeve 16 is fixed to the end of the helical shaft 14. An amplitude transformer 18 is connected to the connecting sleeve 16, and a spring rod 21 is installed at the end of the amplitude transformer 18. When the helical shaft 14 vibrates radially, the amplitude transformer 18... The 8 can rotate relative to the fixed sleeve 17, while the sealing sleeve 19 deforms accordingly when the amplitude rod 18 moves, preventing molten material from entering the fixed sleeve 17 and affecting the movement of the amplitude rod 18. The movement of the amplitude rod 18 also causes the corresponding sealing plate 20 to deform, and the sealing plate 20 is tightly attached to the surface of the amplitude rod 18. Then, the movement of the amplitude rod 18 compresses the spring rod 21. The spring rod 21 absorbs the energy of the amplitude rod 18 through the damping effect, and then slowly releases the energy to the shock-absorbing sleeve 702 with a porous structure. In this way, excessive vibration can be absorbed, ensuring the stability of the screw shaft 14, achieving injection stability, and ensuring injection molding quality.

[0035] Although this disclosure has been described with respect to only a limited number of embodiments, those skilled in the art who benefit from this disclosure will understand that various other embodiments can be devised without departing from the scope of the invention. Therefore, the scope of the invention should be limited only by the appended claims.

Claims

1. An ultrasonic-assisted micro-injection molding device, comprising a frame (1) and a power unit connected to the frame (1), wherein the power unit is connected to a moving mold (5), and a fixed mold (6) is fixedly connected to the frame (1), the power unit being used to drive the moving mold (5) to move and to make the moving mold (5) contact and cooperate with the fixed mold (6), characterized in that, The rack (1) is connected with a material conveying unit, the material conveying unit is connected with an ultrasonic sleeve (12), the rack (1) is provided with an ultrasonic generator (13), the ultrasonic generator (13) is electrically connected with the ultrasonic sleeve (12), the material conveying unit is connected with a fixed mold (6), the material conveying unit is used for injecting plastic melt into a cavity formed by a movable mold (5) and the fixed mold (6), the material conveying unit is connected with a plurality of amplitude rods (18), and all the amplitude rods (18) are elastically connected with the material conveying unit.

2. The ultrasonic-assisted microinjection molding apparatus according to claim 1, wherein The ultrasonic sleeve (12) is externally provided with sound-absorbing cotton.

3. The ultrasonic-assisted microinjection molding apparatus according to claim 1, wherein The power unit comprises first servo motors (2), two first servo motors (2) are arranged on the rack (1) in a vertical distribution mode, two lead screws (3) are rotatably connected to the rack (1), each of the lead screws (3) is fixedly connected with an output shaft of one of the first servo motors (2), two slide rods (4) are fixedly connected to the rack (1), each of the slide rods (4) corresponds to one of the lead screws (3), the fixed mold (6) is rotatably connected with all the lead screws (3), and the fixed mold (6) is slidably connected with all the slide rods (4).

4. The ultrasonic-assisted microinjection molding apparatus according to claim 1, wherein The material conveying unit comprises a material conveying pipe (7), the material conveying pipe (7) is fixedly connected to the rack (1), the material conveying pipe (7) is communicated with a material conveying hopper (8), the material conveying pipe (7) is provided with a second servo motor (9), the material conveying pipe (7) is externally provided with a primary heating sleeve (10), the material conveying pipe (7) is provided with a secondary heating sleeve (11), the secondary heating sleeve (11) is located between the primary heating sleeve (10) and the ultrasonic sleeve (12), the temperature of the secondary heating sleeve (11) is higher than that of the primary heating sleeve (10), the material conveying pipe (7) is rotatably connected with a spiral shaft (14), the spiral shaft (14) is fixedly connected with spiral blades (15) on an outer ring surface, the spiral blades (15) are rotatably connected with an inner wall of the material conveying pipe (7), a tapered sprue (701) is arranged at a left end of the material conveying pipe (7), the sprue (701) is connected with the fixed mold (6), the material conveying pipe (7) is externally connected with a heating assembly, the heating assembly is used for melting plastic particles, and the material conveying pipe (7) is slidably connected with all the amplitude rods (18).

5. The ultrasonic-assisted microinjection molding apparatus according to claim 4, wherein The spiral blades (15) are provided in a hollow structure.

6. The ultrasonic-assisted microinjection molding apparatus according to claim 4, wherein The primary heating sleeve (10) and the secondary heating sleeve (11) are both provided with electromagnetic induction heating modules and temperature sensors.

7. The ultrasonic-assisted microinjection molding apparatus according to claim 4, wherein The spiral shaft (14) is rotatably connected with a connecting sleeve (16) on a side away from the second servo motor (9), a plurality of fixing sleeves (17) are fixedly connected to the connecting sleeve (16), each of the fixing sleeves (17) is rotatably connected with one of the amplitude rods (18), and each of the fixing sleeves (17) is fixedly connected with a sealing sleeve (19), each of the sealing sleeves (19) is fixedly connected with one of the amplitude rods (18).

8. The ultrasonic-assisted microinjection molding apparatus according to claim 7, wherein It also comprises sealing pieces (20) and spring rods (21), each of the amplitude rods (18) is slidably connected with a sealing piece (20), each of the amplitude rods (18) is fixedly connected with a spring rod (21), all the spring rods (21) are connected with the material conveying pipe (7), and the material conveying pipe (7) is fixedly connected with all the sealing pieces (20).

9. The ultrasonic-assisted microinjection molding apparatus according to claim 8, wherein The sealing sleeve (19) and the sealing piece (20) are made of high-temperature-resistant fluorine rubber.

10. The ultrasonic-assisted microinjection molding apparatus according to claim 9, wherein An outer shock sleeve (702) is arranged on the material conveying pipe (7), the shock sleeve (702) is fixedly connected with all the spring rods (21), and the shock sleeve (702) is made of a porous material.

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