A kind of precision injection molding equipment based on servo drive and in-mold sensing feedback anti-blocking injection mechanism and method thereof

Abstract

The present application relates to the technical field of precision injection molding, in particular to a kind of precision injection molding equipment's anti-blocking injection mechanism and method based on servo drive and in-mold sensing feedback, including the mold cavity in the mold device with pressure sensor is configured and is used for injecting melt to the injection device of mold cavity, and the injection end of injection device is equipped with anti-blocking component.The present application monitors the jamming trend in real time by in-mold pressure sensor, and drives servo cylinder to execute the timing action of first rotating cut-off main flow channel, then linear suction dead zone cold material, utilizes negative pressure to actively transfer the melt to be cooled in needle valve front end into annular temporary storage chamber heated and kept, fundamentally eliminates the formation basis of cold plug and black dot.

Description

Technical Field

[0001] This invention relates to the field of precision injection molding technology, and more specifically, to an anti-clogging injection mechanism and method for precision injection molding equipment based on servo drive and in-mold sensing feedback. Background Technology

[0002] In precision injection molding, to prevent melt drooling and achieve pin-point gate, injection molding machines generally use spring-loaded needle valve nozzles at the injection end. These nozzles close the outlet after injection through a built-in valve needle. Although this effectively prevents melt from overflowing, a small amount of melt will remain in the annular stagnation area at the valve needle head during the interval between the end of the holding pressure and the start of the next injection. This part of the melt adheres closely to the nozzle tip and the mold gate sleeve, which are at a lower temperature. Heat is dissipated very quickly, and the melt is easily cooled, degraded, or even carbonized, forming a cold plug or black spot with extremely high viscosity.

[0003] Patent application CN202520814901.8 discloses a nozzle for an injection molding machine with anti-clogging function, including a T-shaped tube and a hollow threaded tube. The bottom of the T-shaped tube is fixedly connected to the hollow threaded tube, and a conical nozzle is fixedly connected to the upper front side of the T-shaped tube. It also includes a blockage-clearing component and auxiliary components. The T-shaped tube is equipped with a blockage-clearing component for inserting into and heating the solidified injection molding material. By starting motors a and b, motor a pushes the heating rod forward via a lead screw, while motor b drives the drill bit to rotate synchronously via a shaft to drill through the solidified injection molding material, facilitating the insertion of the heating rod.

[0004] In existing technologies, most solutions to nozzle clogging problems focus on enhancing external heating, such as adding a heating jacket to the nozzle or using post-operative remedial measures such as heating the drill bit to clear the blockage. However, external heating cannot remove the viscous cold skin layer that has already formed in the center of the flow channel, and it is easy to have the phenomenon of external heat and internal cold. Post-operative blockage clearing requires stopping the machine or interrupting the production cycle, which affects efficiency. In addition, the drilling process may generate metal chips or residues, which pose a secondary pollution risk to precision molding.

[0005] In view of this, this application proposes an anti-clogging injection mechanism and method for a precision injection molding equipment based on servo drive and in-mold sensing feedback. Summary of the Invention

[0006] The purpose of this invention is to provide an anti-clogging injection mechanism and method for a precision injection molding equipment based on servo drive and in-mold sensing feedback. By using negative pressure to actively transfer the melt that is about to cool at the front end of the needle valve to a heated and heat-preserving annular temporary storage cavity, the basis for the formation of cold blockage and black spots is fundamentally eliminated, thereby solving the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] An anti-clogging injection mechanism for a precision injection molding equipment based on servo drive and in-mold sensing feedback includes a mold closing device with a pressure sensor configured inside the mold cavity and an injection device for injecting molten material into the mold cavity, wherein the injection end of the injection device is provided with an anti-clogging component.

[0009] The anti-clogging component includes a reflux device connected to the barrel in the injection device, a check valve connected to the outlet end of the reflux device, a needle valve assembly disposed inside the check valve to prevent the molten material from flowing back, and a driver disposed outside the reflux device.

[0010] The reflux device includes a transition tube, a rotating tube that rotates inside the transition tube, and a feed plate that is clamped to the inner wall of the rotating tube. An annular temporary storage cavity is formed between the transition tube and the rotating tube. An annular piston slides in the annular temporary storage cavity. Two guide grooves are provided on the outer wall of the rotating tube.

[0011] The material outlet end of the material feed plate abuts against the material blocking plate. The material feed plate is provided with a melting channel, and the material blocking plate is provided with a corresponding matching channel.

[0012] The driver includes a pair of levers driven by servo electric cylinders and slidingly engaged with guide grooves;

[0013] In the above configuration, the driver is configured to start in response to a blockage signal from the pressure sensor in the mold clamping device, drive the return valve to perform an anti-blockage action, drive the lever to move along the guide groove, drive the rotating tube to rotate, and drive the material passage plate to rotate relative to the blocking plate, so that the mating channel and the molten material channel are switched from a connected state to a blocked state. At the same time, the driver drives the annular piston to move, generating a negative pressure in the annular temporary storage cavity, and sucking the blocked molten material at the end of the needle valve assembly into the annular temporary storage cavity.

[0014] In the technical solution of the present invention, the reflux device further includes a sliding plate slidably connected in the annular temporary storage cavity, a plurality of connecting rods snapped and fixed between the annular piston and the sliding plate, and a guide rod coaxially connected to the center of the feed plate.

[0015] In the technical solution of the present invention, the upper and lower outer walls of the rotating tube are provided with through grooves, and the inner wall of the rotating tube is integrally formed with an annular plate. The annular plate is located on the discharge side of the feed plate, and multiple circular holes communicating with the annular temporary storage cavity are provided on the annular plate.

[0016] In the technical solution of the present invention, two guide grooves are provided on the outer wall of the rotating tube. The guide grooves include a straight groove extending along the axial direction of the rotating tube and a spiral groove extending circumferentially.

[0017] In the above configuration, the reflux device, through the cooperation of the rotating tube and the annular piston, first cuts off the central flow channel during the anti-blocking action, and then uses negative pressure to accurately suck the cold material at the front end of the nozzle into the annular temporary storage chamber, which is independently insulated by the heating jacket to prevent the cold material from solidifying again.

[0018] In the technical solution of the present invention, the anti-reverse device includes an anti-reverse tube threadedly connected to the discharge end of the transition tube, a feeding ring groove is provided inside the anti-reverse tube, a plurality of discharge holes are provided through the end of the feeding ring groove of the anti-reverse tube, and a sliding hole is provided at the center of the discharge end of the anti-reverse tube.

[0019] In the technical solution of the present invention, the material blocking plate is tightly fitted at the center of the feed end of the check tube, the melting channel on the material passage plate is a plurality of first sector-shaped through grooves penetrating the plate body, and the matching channel on the material blocking plate is a second sector-shaped through groove that matches the shape and position of the first sector-shaped through groove.

[0020] In the above configuration, the feed ring groove and discharge hole of the check valve guide the molten material evenly to the front end of the valve needle assembly, ensuring smooth flow of the molten material during discharge and anti-blocking suction.

[0021] In the technical solution of the present invention, the needle valve assembly includes a valve needle that slides in a sliding hole and a spring sleeved on the outside of the valve needle. One end of the valve needle is tapered and the other end is integrally formed with a valve stem. The valve needle closes the discharge end of the check tube under the elastic force of the spring.

[0022] In the above configuration, the needle valve assembly uses the preload of the spring to achieve the normally closed state of the nozzle outlet. During injection, the molten material pressure pushes the valve needle to overcome the spring force and retract to open. After the pressure holding period ends, the spring force drives the valve needle to reset and close, effectively preventing drooling and backflow of the molten material.

[0023] In the technical solution of the present invention, the driver further includes a movable frame slidably connected to the outside of the return device, the servo electric cylinder is fixedly connected to the end of the injection device barrel by bolts, the end of the telescopic rod of the servo electric cylinder is fixedly connected to the outer wall of the movable frame by bolts, and the end of the lever passes through the lever groove and the slide plate and slides inside the guide groove.

[0024] In the above setup, the driver serves as the sole power source for the anti-blocking action. The high-precision characteristics of the servo electric cylinder ensure that the movement trajectory of the lever within the guide groove is precisely controllable, achieving a sequential action of first rotating to cut off the flow and then directly pulling back.

[0025] In the technical solution of the present invention, the anti-clogging component further includes a feed pipe, a nozzle threadedly sealed to the discharge end of the check pipe, and a heating sleeve sleeved on the outside of the reflux device and the check pipe. One end of the feed pipe is connected to the barrel of the injection device, and the other end is threadedly sealed to the feed end of the reflux device. The heating sleeve is used to independently heat and keep the molten material in the annular temporary storage cavity warm.

[0026] On the other hand, the present invention also provides an anti-clogging method for a precision injection molding machine based on servo drive and in-mold sensing feedback. The anti-clogging injection mechanism of the above-mentioned precision injection molding machine based on servo drive and in-mold sensing feedback includes the following steps:

[0027] S1. During a normal injection molding cycle, the molten material from the injection unit flows sequentially through the feed pipe 310, the inside of the rotating pipe 322, the fan-shaped groove aligned with the material guide plate 326 and the material blocking plate 332, and the feed ring groove 3310. After entering the front end of the needle valve assembly through the discharge hole 3311, it pushes open the valve needle 340 and is injected into the mold cavity of the mold closing device through the nozzle 360. After the pressure holding is completed, the valve needle 340 closes the nozzle 360 ​​outlet under the action of the spring 350, the injection unit 200 performs pre-plasticizing, and the mold opens to remove the part. The pressure sensor configured in the mold closing device monitors the mold cavity pressure in real time. When the monitored pressure value exceeds the preset threshold, it is determined to be a blockage signal. The controller determines that a blockage trend has occurred and sends a blockage signal to trigger the anti-blocking program. This signal directly triggers the driver in the anti-blocking component during the mold disassembly stage of the mold closing device.

[0028] S2. The servo electric cylinder inside the driver drives its telescopic rod to retract, causing the moving frame to move axially along the outer wall of the transition tube toward one end of the feed tube. A pair of levers fixed on the moving frame synchronously drive the sliding plate to move axially along the outer wall of the rotating tube.

[0029] S3. Entering the flow channel cutting stage, as the lever moves with the moving frame, its end first moves along the spiral groove section of the guide groove on the outer wall of the rotating tube, pushing the rotating tube to rotate 60° relative to the transition tube. After rotating to the correct position, the end of the lever disengages from the spiral groove section and enters the straight groove section connected to the spiral groove section to continue axial movement. At this time, the material passage plate fixed on the inner wall of the rotating tube rotates 60° synchronously with the rotating tube, so that the first sector-shaped passage on the material passage plate and the second sector-shaped passage on the material blocking plate fixed in the anti-reverse device are switched from an axially aligned connected state to a completely staggered blocking state, thereby cutting off the main flow channel of the molten material. This prevents the molten material in the rotating tube from being mistakenly sucked into the annular temporary storage cavity during subsequent suction, ensuring that all the molten material acting on the nozzle tip is suctioned, thus ensuring the anti-blocking effect.

[0030] S4. After the rotating tube completes a 60° rotation, the lever continues to move axially within the straight groove section. At the same time, the slide plate pulls the annular piston through the connecting rod, causing it to slide axially away from the nozzle along the annular temporary storage cavity between the transition tube and the rotating tube. This generates a negative pressure in the annular temporary storage cavity. The negative pressure is transmitted through the circular hole on the ring plate to the inside of the rotating tube and the front end of the needle valve assembly, drawing the molten material retained at the front end of the nozzle into the annular temporary storage cavity through the circular hole.

[0031] S5. Subsequently, the heating sleeve fitted outside the transition tube and the rotating tube independently heats and keeps the blockage molten material drawn into the annular temporary storage cavity, maintaining its molten state.

[0032] S6. When the blockage is cleared and before the next injection begins, the servo cylinder reverses its drive, causing the moving frame to move in the opposite direction to the nozzle; the annular piston slides in the opposite direction with the sliding plate and connecting rod, pushing the molten material temporarily stored in the annular storage cavity back into the check tube through the round hole on the annular plate; at the same time, the end of the lever enters the spiral groove section from the straight groove section of the guide groove, causing the rotating tube to rotate 60° in the opposite direction, so that the first sector through groove and the second sector through groove are axially aligned again, restoring the connection of the main channel of molten material;

[0033] S7. The injection unit then resumes normal injection molding operation. The molten material flows sequentially through the feed pipe, return valve, check valve and nozzle, and is injected into the mold cavity of the mold closing device to continue the molding production of subsequent products.

[0034] Compared with the prior art, the beneficial effects of the present invention are:

[0035] 1. The anti-clogging injection mechanism and method of the precision injection molding equipment based on servo drive and in-mold sensing feedback monitor the clogging trend in real time through an in-mold pressure sensor, and drive the servo electric cylinder to perform a sequential action of first rotating to cut off the main channel and then linearly sucking up the cold material in the dead zone. The negative pressure is used to actively transfer the melt that is about to cool at the front end of the needle valve to the heated and heat-preserving annular temporary storage cavity, which fundamentally eliminates the basis for the formation of cold blockage and black spots.

[0036] 2. The anti-clogging injection mechanism and method of this precision injection molding equipment based on servo drive and in-mold sensing feedback, drives the rotating tube to rotate through the spiral section of the guide groove before suction, so that the fan-shaped grooves of the material pass plate and the material block plate are staggered, completely cutting off the connection between the central flow channel and the annular temporary storage cavity, ensuring that the negative pressure only acts on the dead zone melt material at the front end of the nozzle, and will not mistakenly draw away the subsequent hot melt material, thus ensuring the accuracy of suction and the effectiveness of anti-clogging.

[0037] 3. The anti-clogging injection mechanism and method of the precision injection molding equipment based on servo drive and in-mold sensing feedback. The mechanism has a compact structure and can be directly installed at the front end of the barrel of the existing injection device without changing the main structure and function of the original needle valve nozzle. It has good compatibility and low modification cost. At the same time, the melt that is sucked away is independently heated and kept warm in the annular temporary storage chamber and is pushed back to the main runner for reuse before the start of the next cycle. There is no waste of raw materials and the economy is high. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0039] Figure 2 This is a partial cross-sectional schematic diagram of the present invention;

[0040] Figure 3 This is a schematic diagram of the anti-clogging component in the present invention;

[0041] Figure 4 This is a cross-sectional schematic diagram of the anti-clogging component in this invention;

[0042] Figure 5 This is a cross-sectional side view of the anti-clogging component in this invention;

[0043] Figure 6 This is a cross-sectional schematic diagram of the reflux device in this invention;

[0044] Figure 7 This is a schematic diagram of the transition tube in this invention;

[0045] Figure 8 This is a partial structural diagram of the reflux device in this invention;

[0046] Figure 9 This is a schematic diagram of the rotating tube in this invention;

[0047] Figure 10 This is a cross-sectional schematic diagram of the structure of the anti-reverse device of the present invention;

[0048] Figure 11 This is a schematic diagram of the structure of the stop-reverse tube of the present invention;

[0049] Figure 12 This is a schematic diagram of the driver structure in this invention;

[0050] Explanation of reference numerals in the attached figures:

[0051] 100. Mold closing device;

[0052] 200. Injection device;

[0053] 300. Anti-clogging component; 310. Feed pipe; 320. Return valve; 321. Transition pipe; 3210. Slot; 3211. Ring plate; 322. Rotating pipe; 3220. Guide groove; 323. Annular piston; 324. Sliding plate; 325. Connecting rod; 326. Feeding plate; 327. Guide rod; 330. Backflow preventer; 331. Backflow preventer; 3310. Feeding ring groove; 3311. Discharge hole; 3312. Sliding hole; 332. Material blocking plate; 340. Valve needle; 341. Valve stem; 350. Spring; 360. Nozzle; 370. Driver; 371. Servo electric cylinder; 372. Moving frame; 373. Lever; 380. Heating jacket. Detailed Implementation

[0054] The technical solutions of this invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0055] Please see Figure 1 As shown, this embodiment provides a technical solution:

[0056] An anti-clogging injection mechanism for a precision injection molding equipment based on servo drive and in-mold sensing feedback includes a mold clamping device 100 with a pressure sensor configured in the mold cavity and an injection device 200 for injecting molten material into the mold cavity. The injection end of the injection device 200 is provided with an anti-clogging component 300.

[0057] Furthermore, the mold closing device 100 includes a fixed template, a movable template, a mold closing cylinder, and a mold. The mold has a cavity inside, and a pressure sensor is embedded in the inner wall of the cavity near the mold gate sleeve to monitor the pressure change of the molten material at the gate in real time.

[0058] Furthermore, the injection device 200 includes a barrel, a screw disposed inside the barrel, and a servo drive system for driving the screw to rotate and move axially. A heating coil is provided on the outer periphery of the barrel for plasticizing the solid raw material into a molten state.

[0059] In the above configuration, the mold closing device 100 is responsible for closing the mold and providing clamping force, and the injection device 200 is responsible for plasticizing the raw material and injecting the molten material. The two work together to complete the injection molding cycle. The pressure sensor configured in the mold cavity can sense the state of the molten material at the gate in real time and provide a trigger signal for the anti-blocking component 300.

[0060] Please see Figures 2-9As shown, in this embodiment, the anti-clogging component 300 includes a feed pipe 310, a reflux device 320 connected to the material cylinder in the injection device 200, a check valve 330 connected to the discharge end of the reflux device 320, a needle valve assembly disposed inside the check valve 330 to prevent the molten material from flowing back, a nozzle 360, a driver 370 disposed outside the reflux device 320, and a heating jacket 380 sleeved outside the reflux device 320 and the check valve 330. The needle valve assembly includes a valve needle 340 and a spring 350.

[0061] Furthermore, one end of the feed pipe 310 is connected to the barrel of the injection device 200, and the other end is threadedly sealed to the feed end of the reflux device 320, for guiding the molten material in the barrel into the reflux device 320.

[0062] Furthermore, the reflux device 320 includes a transition tube 321, a rotating tube 322 rotating within the transition tube 321, an annular piston 323, a sliding plate 324, several connecting rods 325 snapped and fixed between the annular piston 323 and the sliding plate 324, a feed plate 326 snapped onto the inner wall of the rotating tube 322, and a guide rod 327 coaxially connected to the center of the feed plate 326. An annular temporary storage cavity is formed between the transition tube 321 and the rotating tube 322. The annular piston 323 and the sliding plate 324 are slidably connected within the annular temporary storage cavity. The heating jacket 380 is used to independently heat and maintain the temperature of the molten material in the annular temporary storage cavity. The heating jacket 380 is an electric heating coil and is equipped with an independent temperature control module.

[0063] Furthermore, the discharge end of the feed plate 326 abuts against the baffle plate 332. The feed plate 326 is provided with a molten material channel, and the baffle plate 332 is provided with a corresponding matching channel. The guide rod 327 is used to guide the molten material to flow smoothly and reduce dead zones and stagnation.

[0064] Furthermore, grooves 3210 are provided through the upper and lower outer walls of the rotating tube 322, and an annular piece 3211 is integrally formed on the inner wall of the rotating tube 322. The annular piece 3211 is located on the discharge side of the feed plate 326, and multiple circular holes communicating with the annular temporary storage cavity are provided on the annular piece 3211.

[0065] Furthermore, two guide grooves 3220 are provided on the outer wall of the rotating tube 322. The guide groove 3220 includes a straight groove extending along the axial direction of the rotating tube 322 and a spiral groove extending along its circumference. The spiral angle of the spiral groove is set to make the rotation angle of the rotating tube 322 60° so that the mating channel and the molten material channel are completely misaligned when the anti-blocking action is performed.

[0066] Furthermore, the feed pipe 310 stably guides the plasticized molten material from the injection unit 200 into the return pipe 320; an annular temporary storage cavity is formed between the transition pipe 321 and the rotating pipe 322 inside the return pipe 320. This annular temporary storage cavity does not participate in the flow of molten material during normal injection, but only serves as a temporary storage and warming space for cold material during anti-blocking action; the cooperation between the feed plate 326 and the blocking plate 332 constitutes the on / off switch of the central flow channel, and the flow channel can be connected or blocked by the relative rotation of the two; the circular hole on the ring plate 3211 is the only channel connecting the annular temporary storage cavity and the central flow channel, ensuring that the cold material is accurately drawn into the annular temporary storage cavity during negative pressure suction, while during normal injection, because the feed plate and the blocking plate are aligned and the molten material preferentially flows along the main flow channel with low pressure drop, very little enters the annular temporary storage cavity; the heating jacket 380 is independent of the barrel heating system and is used specifically for heat preservation of the molten material in the annular temporary storage cavity.

[0067] In the above configuration, the reflux 320, through the cooperation of the rotating tube 322 and the annular piston 323, first cuts off the central flow channel during the anti-blocking action, and then uses negative pressure to accurately suck the cold material at the front end of the nozzle into the annular temporary storage chamber, which is independently kept warm by the heating jacket 380 to prevent the cold material from solidifying again.

[0068] Please see Figures 4-11 As shown, in this embodiment, the check valve 330 includes a check pipe 331 threadedly connected to the discharge end of the transition pipe 321. The inside of the check pipe 331 is provided with a feeding ring groove 3310. The check pipe 331 has a plurality of discharge holes 3311 through the end of the feeding ring groove 3310. A sliding hole 3312 is provided at the center of the discharge end of the check pipe 331. The nozzle 360 ​​is threadedly sealed to the discharge end of the check pipe 331.

[0069] Furthermore, the baffle plate 332 is tightly fitted at the center of the feed end of the check pipe 331. The molten material channel on the feed plate 326 is a plurality of first sector-shaped channels penetrating the plate body, and the matching channel on the baffle plate 332 is a second sector-shaped channel that matches the shape and position of the first sector-shaped channels. When the feed plate 326 and the baffle plate 332 are in the initial position of relative rotation, the first sector-shaped channels and the second sector-shaped channels are axially aligned to form a continuous passage for the molten material to pass through; when the feed plate 326 rotates relative to the baffle plate 332 by a predetermined angle, the first sector-shaped channels and the second sector-shaped channels are completely misaligned, cutting off the molten material passage.

[0070] Furthermore, the feeding ring groove 3310 is an annular groove formed on the inner wall of the check tube 331, which is circumferentially connected to each discharge hole 3311, so that the molten material flowing out from the fan-shaped through groove can be evenly distributed to each discharge hole 3311, ensuring that the valve needle 340 is subjected to uniform force in the circumference.

[0071] Furthermore, the discharge holes 3311 are evenly distributed around the axis of the check pipe 331, and their axis direction forms an acute angle with the axis of the check pipe 331, tilting towards the discharge end, so as to facilitate the smooth flow of molten material to the nozzle 360.

[0072] Furthermore, the check valve 330 receives the molten material from the return valve 320 and guides it evenly to the front end of the valve needle 340 through the feed ring groove 3310 and the discharge hole 3311. The feed plate 326 and the blocking plate 332 are fitted with fan-shaped grooves, which not only ensures sufficient flow area during normal injection, but also achieves complete cutting after rotating 60°. The circumferential staggered design of the fan-shaped grooves makes the rotation angle required for the cutting action small, the response fast, and there are no gaps left after cutting, ensuring the thoroughness of the flow channel blockage. The threaded connection between the check pipe 331 and the transition pipe 321 facilitates disassembly, maintenance, and replacement of the blocking plate 332.

[0073] In the above configuration, the feed ring groove 3310 and discharge hole 3311 of the check valve 330 guide the molten material evenly to the front end of the valve needle assembly, ensuring smooth flow of the molten material during discharge and anti-blocking suction.

[0074] Please see Figures 4-11 As shown, in this embodiment, the needle valve assembly includes a valve needle 340 that slides in the sliding hole 3312 and a spring 350 sleeved on the outside of the valve needle 340. One end of the valve needle 340 is tapered, and the other end is integrally formed with a valve stem 341. The valve needle 340 closes the discharge end of the check tube 331 under the elastic force of the spring 350.

[0075] Furthermore, the pre-compression of the spring 350 ensures a reliable seal of the valve needle 340 to the nozzle 360 ​​outlet when not in the injection state. The mating section between the sliding hole 3312 and the valve needle 340 is precision ground to ensure smooth sliding of the valve needle 340 and effectively reduce leakage of molten material along the mating gap.

[0076] In the above configuration, the needle valve assembly uses the preload of the spring 350 to achieve the normally closed state of the nozzle 360 ​​outlet. During injection, the molten material pressure pushes the valve needle 340 to overcome the spring force and open. After the pressure holding period ends, the spring force drives the valve needle 340 to reset and close, effectively preventing molten material from drooling and backflowing.

[0077] Please see Figures 4-12 As shown, in this embodiment, the driver 370 includes a pair of levers 373 driven by servo cylinders 371 and slidably engaged with guide grooves 3220, and a movable frame 372 slidably connected to the outside of the return device 320. The servo cylinders 371 are fixedly connected to the end of the injection device 200 barrel by bolts, and the telescopic rod end of the servo cylinders 371 is fixedly connected to the outer wall of the movable frame 372 by bolts. The end of the levers 373 passes through the lever groove 3210 and the slide plate 324 and slides inside the guide groove 3220.

[0078] Furthermore, the driver 370 is configured to start in response to a blockage signal from the pressure sensor in the mold clamping device 100, drive the return valve 320 to perform an anti-blockage action, drive the lever 373 to move along the guide groove 3220, drive the rotating tube 322 to rotate, and drive the material passage plate 326 to rotate relative to the blocking plate 332, so that the mating channel and the molten material channel are switched from a connected state to a blocked state. At the same time, drive the annular piston 323 to move, generate negative pressure in the annular temporary storage cavity, and draw the blocked molten material at the end of the needle valve assembly into the annular temporary storage cavity.

[0079] The servo electric cylinder 371 is fixedly connected to the end of the barrel of the injection device 200 by bolts, and two symmetrically arranged levers 373 are threadedly connected to the moving frame 372. The telescopic rod end of the servo electric cylinder 371 is fixedly connected to the outer wall of the moving frame 372 by bolts. The end of the lever 373 passes through the lever groove 3210 and the slide plate 324 and slides inside the guide groove 3220.

[0080] Furthermore, the servo electric cylinder 371 is a precision ball screw type servo electric cylinder with a repeatability of not less than ±0.01mm, which can precisely control the axial displacement of the annular piston 323, thereby precisely controlling the volume of molten material sucked into the annular temporary storage chamber. The moving frame 372 has a frame structure and is fitted around the outer periphery of the transition tube 321. Its inner wall is fitted with the outer wall of the transition tube 321 through a sliding bushing to ensure the smoothness and straightness of the axial movement of the moving frame 372. The end of the lever 373 is hemispherical, and the two levers 373 are symmetrically arranged to balance the rotational torque on the rotating tube 322 and avoid uneven loading and jamming. The frame structure and sliding fit of the moving frame 372 provide stable support and guidance for the lever 373, ensuring the reliable execution of the entire anti-blocking action.

[0081] In the above setup, the driver 370 serves as the sole power source for the anti-blocking action. The high-precision characteristics of the servo electric cylinder 371 ensure that the movement trajectory of the lever 373 within the guide groove 3220 is precisely controllable, realizing the sequential action of first rotating to cut off the flow and then directly pulling back.

[0082] The anti-clogging method for a precision injection molding machine based on servo drive and in-mold sensor feedback of the present invention, using the aforementioned anti-clogging injection mechanism of the precision injection molding machine based on servo drive and in-mold sensor feedback, includes the following steps:

[0083] S1. During a normal injection molding cycle, the molten material from the injection unit 200 flows sequentially through the feed pipe 310, the inside of the rotating pipe 322, the fan-shaped groove aligned with the material guide plate 326 and the material blocking plate 332, and the feed ring groove 3310. After entering the front end of the needle valve assembly through the discharge hole 3311, it pushes open the valve needle 340 and is injected into the mold cavity of the mold closing device 100 through the nozzle 360. After the pressure holding is completed, the valve needle 340 closes the nozzle 360 ​​outlet under the action of the spring 350, the injection unit 200 performs pre-plasticizing, and the mold is opened to remove the part. The pressure sensor configured in the mold closing device 100 monitors the mold cavity pressure in real time. When the monitored pressure value exceeds the preset threshold, it is determined to be a blockage signal. The controller determines that a blockage trend has occurred and sends a blockage signal to trigger the anti-blocking program. This signal directly triggers the driver 370 in the anti-blocking component 300 during the mold disassembly stage of the mold closing device 100.

[0084] S2, the servo electric cylinder 371 in the driver 370 drives its telescopic rod to retract, causing the moving frame 372 to move axially along the outer wall of the transition tube 321 toward one end of the feed tube 310. A pair of levers 373 fixed on the moving frame 372 synchronously drive the slide 324 to move axially along the outer wall of the rotating tube 322.

[0085] S3. Entering the flow channel cutting stage, as the lever 373 moves with the moving frame 372, its end first moves along the spiral groove section of the guide groove 3220 on the outer wall of the rotating tube 322, pushing the rotating tube 322 to rotate 60° relative to the transition tube 321. After rotating to the correct position, the end of the lever 373 disengages from the spiral groove section and enters the straight groove section connected to the spiral groove section to continue axial movement. At this time, the material passage plate 326 fixed on the inner wall of the rotating tube 322 rotates 60° synchronously with the rotating tube 322, so that the first sector-shaped passage on the material passage plate 326 and the second sector-shaped passage on the blocking plate 332 fixed in the anti-reverse device 330 are switched from an axially aligned connected state to a completely staggered blocking state, thereby cutting off the main flow channel of the molten material. This prevents the molten material in the rotating tube from being mistakenly sucked into the annular temporary storage cavity during subsequent suction, ensuring that all the molten material acting on the nozzle tip is suctioned, thus ensuring the anti-blocking effect.

[0086] S4. After the rotating tube 322 completes a 60° rotation, the lever 373 continues to move axially within the straight groove section. At the same time, the slide plate 324 pulls the annular piston 323 through the connecting rod 325, causing it to slide axially away from the nozzle 360 ​​along the annular temporary storage cavity between the transition tube 321 and the rotating tube 322. This generates a negative pressure in the annular temporary storage cavity. The negative pressure is transmitted through the circular hole on the ring plate 3211 to the inside of the rotating tube 322 and the front end of the needle valve assembly, drawing the molten material retained at the front end of the nozzle 360 ​​into the annular temporary storage cavity through the circular hole.

[0087] S5. Subsequently, the heating sleeve 380, which is fitted outside the transition tube 321 and the rotating tube 322, independently heats and keeps the blockage molten material drawn into the annular temporary storage cavity, maintaining its molten state.

[0088] S6. When the blockage is cleared and before the next injection begins, the servo cylinder 371 reverses its drive, causing the moving frame 372 to move in the opposite direction toward the nozzle 360. The annular piston 323 slides in the opposite direction with the sliding plate 324 and the connecting rod 325, pushing the molten material temporarily stored in the annular storage cavity back into the check tube 331 through the round hole on the annular plate 3211. At the same time, the end of the lever 373 enters the spiral groove section from the straight groove section of the guide groove 3220, causing the rotating tube 322 to rotate 60° in the opposite direction, so that the first sector-shaped through groove and the second sector-shaped through groove are re-axially aligned, restoring the connection of the main channel of the molten material.

[0089] S7. The injection unit 200 then resumes normal injection molding operation. The molten material flows sequentially through the feed pipe 310, return device 320, check valve 330 and nozzle 360, and is injected into the mold cavity of the mold closing device 100 to continue the molding production of subsequent products.

[0090] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the specification and its equivalents.

Claims

1. An anti-clogging injection mechanism for a precision injection molding machine based on servo drive and in-mold sensing feedback, comprising a mold closing device with a pressure sensor configured inside the mold cavity and an injection device for injecting molten material into the mold cavity, characterized in that: The injection end of the injection device is equipped with an anti-clogging component; The anti-clogging component includes a reflux device connected to the barrel in the injection device, a check valve connected to the outlet end of the reflux device, a needle valve assembly disposed inside the check valve to prevent the molten material from flowing back, and a driver disposed outside the reflux device. The reflux device includes a transition tube, a rotating tube that rotates inside the transition tube, and a feed plate that is clamped to the inner wall of the rotating tube. An annular temporary storage cavity is formed between the transition tube and the rotating tube. An annular piston slides in the annular temporary storage cavity. Two guide grooves are provided on the outer wall of the rotating tube. The material outlet end of the material feed plate abuts against the material blocking plate. The material feed plate is provided with a melting channel, and the material blocking plate is provided with a corresponding matching channel. The driver includes a pair of levers driven by servo electric cylinders and slidingly engaged with guide grooves; The driver is configured to activate in response to a blockage signal from a pressure sensor within the mold clamping device, drive the return valve to perform an anti-blockage action, drive the lever to move along the guide groove, causing the rotating tube to rotate, and causing the material pass plate to rotate relative to the blocking plate, switching the mating channel and the molten material channel from a connected state to a blocked state. At the same time, it drives the annular piston to move, generating negative pressure in the annular temporary storage cavity, drawing the blocked molten material at the end of the needle valve assembly into the annular temporary storage cavity.

2. The anti-clogging injection mechanism of the precision injection molding equipment based on servo drive and in-mold sensing feedback according to claim 1, characterized in that: The reflux device also includes a sliding plate slidably connected in the annular temporary storage cavity, several connecting rods snapped and fixed between the annular piston and the sliding plate, and a guide rod coaxially connected to the center of the feed plate.

3. The anti-clogging injection mechanism of the precision injection molding equipment based on servo drive and in-mold sensing feedback according to claim 2, characterized in that: The rotating tube has through grooves on its upper and lower outer walls, and an annular plate is integrally formed on its inner wall. The annular plate is located on the discharge side of the feed plate, and multiple circular holes are formed on the annular temporary storage cavity.

4. The anti-clogging injection mechanism of the precision injection molding equipment based on servo drive and in-mold sensing feedback according to claim 3, characterized in that: The guide groove includes a straight groove extending axially along the rotating tube and a spiral groove extending circumferentially along it.

5. The anti-clogging injection mechanism of the precision injection molding equipment based on servo drive and in-mold sensing feedback according to claim 4, characterized in that: The anti-reverse device includes an anti-reverse tube threaded to the discharge end of the transition tube. The anti-reverse tube has a feeding ring groove inside. Several discharge holes are opened through the end of the feeding ring groove of the anti-reverse tube. A sliding hole is opened at the center of the discharge end of the anti-reverse tube.

6. The anti-clogging injection mechanism of the precision injection molding equipment based on servo drive and in-mold sensing feedback according to claim 5, characterized in that: The material blocking plate is tightly fitted at the center of the feed end of the check tube. The melting channel on the material passage plate is a plurality of first sector-shaped through slots that penetrate the plate body. The matching channel on the material blocking plate is a second sector-shaped through slot that matches the shape and position of the first sector-shaped through slot.

7. The anti-clogging injection mechanism of the precision injection molding equipment based on servo drive and in-mold sensing feedback according to claim 6, characterized in that: The needle valve assembly includes a valve needle that slides in a sliding hole and a spring sleeved on the outside of the valve needle. One end of the valve needle is tapered and the other end is integrally formed with a valve stem. The valve needle closes the discharge end of the check tube under the elastic force of the spring.

8. The anti-clogging injection mechanism of the precision injection molding equipment based on servo drive and in-mold sensing feedback according to claim 7, characterized in that: The driver also includes a movable frame slidably connected to the outside of the return device. The servo electric cylinder is fixedly connected to the end of the injection device barrel by bolts. The end of the telescopic rod of the servo electric cylinder is fixedly connected to the outer wall of the movable frame by bolts. The end of the lever passes through the lever groove and the slide plate and slides inside the guide groove.

9. The anti-clogging injection mechanism of the precision injection molding equipment based on servo drive and in-mold sensing feedback according to claim 8, characterized in that: The anti-clogging component also includes a feed pipe, a nozzle threadedly sealed to the discharge end of the check pipe, and a heating sleeve fitted on the outside of the reflux device and the check pipe. One end of the feed pipe is connected to the barrel of the injection device, and the other end is threadedly sealed to the feed end of the reflux device. The heating sleeve is used to independently heat and keep the molten material in the annular temporary storage cavity warm.

10. A method for preventing clogging in a precision injection molding machine based on servo drive and in-mold sensing feedback, using the anti-clogging injection mechanism of the precision injection molding machine based on servo drive and in-mold sensing feedback as described in claim 9, characterized in that... Includes the following steps: S1. During a normal injection molding cycle, the pressure sensor installed in the mold clamping device monitors the mold cavity pressure in real time. When the monitored pressure value exceeds the preset threshold, it is determined to be a blockage signal. This signal directly triggers the driver in the anti-blocking component during the mold disassembly stage of the mold clamping device. S2. The servo electric cylinder inside the driver drives its telescopic rod to retract, causing the moving frame to move axially along the outer wall of the transition tube toward one end of the feed tube. A pair of levers fixed on the moving frame synchronously drive the sliding plate to move axially along the outer wall of the rotating tube. S3. Entering the flow channel cutting stage, as the lever moves with the moving frame, its end first moves along the spiral groove section of the guide groove on the outer wall of the rotating tube, pushing the rotating tube to rotate 60° relative to the transition tube. After rotating to the position, the end of the lever disengages from the spiral groove section and enters the straight groove section connected to the spiral groove section to continue axial movement. At this time, the material passage plate fixed on the inner wall of the rotating tube rotates 60° synchronously with the rotating tube, so that the first sector-shaped passage on the material passage plate and the second sector-shaped passage on the material blocking plate fixed in the anti-reverse device are switched from an axially aligned connected state to a completely staggered blocking state, thereby cutting off the main flow channel of the molten material. S4. After the rotating tube completes a 60° rotation, the lever continues to move axially within the straight groove section. At the same time, the slide plate pulls the annular piston through the connecting rod, causing it to slide axially away from the nozzle along the annular temporary storage cavity between the transition tube and the rotating tube. This generates a negative pressure in the annular temporary storage cavity. The negative pressure is transmitted through the circular hole on the ring plate to the inside of the rotating tube and the front end of the needle valve assembly, drawing the molten material retained at the front end of the nozzle into the annular temporary storage cavity through the circular hole. S5. Subsequently, the heating sleeve fitted outside the transition tube and the rotating tube independently heats and keeps the blockage molten material drawn into the annular temporary storage cavity, maintaining its molten state. S6. When the blockage is cleared and before the next injection begins, the servo cylinder reverses its drive, causing the moving frame to move in the opposite direction to the nozzle; the annular piston slides in the opposite direction with the sliding plate and connecting rod, pushing the molten material temporarily stored in the annular storage cavity back into the check tube through the round hole on the annular plate; at the same time, the end of the lever enters the spiral groove section from the straight groove section of the guide groove, causing the rotating tube to rotate 60° in the opposite direction, so that the first sector through groove and the second sector through groove are axially aligned again, restoring the connection of the main channel of molten material; S7. The injection unit then resumes normal injection molding operation. The molten material flows sequentially through the feed pipe, return valve, check valve and nozzle, and is injected into the mold cavity of the mold closing device to continue the molding production of subsequent products.

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