Nozzle for injection molding machine

Abstract

The invention relates to the technical field of plastic forming, and discloses a nozzle for an injection molding machine, the nozzle comprises a nozzle body, two extrusion blocks and a driving structure, the driving structure comprises a telescopic groove for the extrusion blocks to stretch out and draw back in a sealed mode and a sliding groove communicated with the telescopic groove, the sliding groove is internally provided with a driving block in a sealed and telescopic mode, and a tension spring is arranged between the telescopic groove and the extrusion blocks; a first spring is arranged between the sliding groove and the driving block, a pressure relief structure and a one-way air supply structure are arranged in the shell wall of the nozzle body, and after the nozzle opening is blocked, the pressure in the nozzle body is increased, and the driving block is driven to retract so that the extrusion block can partially stretch out; when the internal pressure of the telescopic groove is too large, the pressure is released, the extrusion block elastically retracts, the liquid plastic is sprayed out with the broken solidified plastic, the internal pressure of the nozzle body is reduced, the driving block elastically extends out to reset, and air supply is completed at the same time, so that the nozzle can be timely and automatically dredged after the nozzle opening is blocked; the risk that a machine is damaged due to too large pressure in the nozzle body is greatly reduced, manual dredging is not needed, and safety is improved.

Description

Technical Field

[0001] The invention relates to the technical field of plastic molding, in particular to a nozzle for an injection molding machine. Background Art

[0002] Injection molding machines are equipment used to produce plastic products. In the production process of plastic products, the nozzle of the injection molding machine needs to be inserted into the mold to inject material into the mold cavity so that the product can be formed. Therefore, the nozzle is an important device for injecting materials in the injection molding machine. Since the nozzle has a small diameter and does not have a heating function, it is easy to accumulate solidified materials or impurities that are not completely melted, resulting in blockage. The nozzle needs to be disassembled and cleaned regularly, which is troublesome and time-consuming. Therefore, a nozzle that can be unblocked without disassembly has appeared.

[0003] The Chinese patent application number 202111329958.1 discloses a nozzle for an injection molding machine, including a tube body and two pressing blocks movably connected to a slide groove running through the inside and outside of the tube body, the opposite surfaces of the two pressing blocks can fit together, a rotating member is rotatably connected in the tube body, and the surfaces of the two pressing blocks and the rotating member that fit together are provided with meshing plane thread teeth and plane thread tooth grooves, and the rotating member rotates to drive the two pressing blocks to slide toward or away from each other in the slide groove. A wrench is provided on the outer circumference of the rotating member, and an annular groove is provided on the tube body corresponding to the wrench position.

[0004] In the above scheme, when the worker pulls the wrench to slide in the annular groove, the rotating part rotates forward, driving the two pressing blocks to approach each other to compress or crush the block plastic, and the crushed solidified plastic can be sprayed out with the subsequent liquid plastic or re-integrated into the liquid plastic. After the nozzle is unblocked, the worker pulls the wrench to drive the rotating part to rotate in the opposite direction, driving the two pressing blocks away from each other to form a channel for the liquid plastic to spray out.

[0005] However, in actual production, impurities in the liquid plastic cannot be completely removed; or the nozzle mouth is far away from the heating position, causing it to cool down quickly. After multiple continuous injections, the liquid plastic accumulates in the nozzle mouth and cools and solidifies. The above situations will cause the nozzle mouth to be blocked during the production process.

[0006] At this time, the temperature near the nozzle is high and the nozzle mouth is plugged into the mold, so it is too difficult and risky to manually drive the wrench to rotate.

[0007] In addition, in the prior art, the method of detecting whether the nozzle is blocked during the production process is to set up a sensor to detect the pressure change inside the nozzle. However, the temperature inside the nozzle is often high, which will cause the pressure sensor to have the risk of reduced accuracy, failure or even damage. It is impossible to provide feedback in time after the nozzle is blocked, and there is a risk of damaging the machine. Summary of the invention

[0008] The present invention aims to address the shortcomings in the prior art of the risk of damage to the machine due to the inability to provide timely feedback after the nozzle is clogged, as well as the difficulty and risk of manually driving a wrench to unclog the nozzle under high temperature conditions. The present invention provides a nozzle for an injection molding machine that can unclog the nozzle in time and has a high degree of safety.

[0009] In order to solve the above technical problems, the present invention is solved by the following technical solutions: A nozzle for an injection molding machine comprises a nozzle body, wherein the inner wall of the nozzle opening of the nozzle body is symmetrically telescopically provided with two extrusion blocks which can approach each other to crush the solidified plastic blocked at the nozzle opening when partially extended and move away from each other to reset when retracted, wherein the movement of the two extrusion blocks is controlled by a driving structure, wherein the driving structure comprises a telescopic groove concavely provided on the inner wall of the nozzle opening for the extrusion blocks to seal and elastically extend, and a sliding groove concavely provided on the inner wall of the nozzle body and connected to the telescopic groove, wherein the sliding groove is sealed and elastically telescopically provided with a driving block which elastically retracts and squeezes air to drive the extrusion blocks to partially extend when the nozzle opening is blocked and the pressure in the nozzle body increases to be equal to or greater than a first preset value. A pressure relief structure is arranged in the shell wall of the nozzle body, which releases pressure when the air pressure inside the telescopic groove is equal to or greater than a second preset value and closes when the air pressure inside the telescopic groove is reduced to less than the second preset value; a tension spring is arranged between the telescopic groove and the extrusion block, which drives the extrusion block to retract and reset after the pressure in the telescopic groove is released; a first spring is arranged between the sliding groove and the driving block, which drives the driving block to extend and reset when the liquid plastic carries the broken solidified plastic and is ejected from the nozzle mouth, so that the pressure inside the nozzle body is reduced to less than the first preset value; a one-way air replenishing structure is arranged on the shell wall of the nozzle body, which replenishes air into the telescopic groove and the sliding groove when the driving block is reset.

[0010] With the above solution, when the nozzle is not blocked, the liquid plastic can be ejected smoothly through the nozzle, and the pressure in the nozzle body is always less than the first preset value. When the nozzle is blocked, the liquid plastic cannot be ejected through the nozzle, but the liquid plastic is still being continuously transferred to the nozzle body, so that the pressure in the nozzle body continues to increase until it is equal to or greater than the first preset value. At this time, the driving block is sealed and retracted under the pressure of the liquid plastic. Since the sliding groove and the telescopic groove are connected, the air inside the two is compressed, and the air pressure continues to increase. The extrusion block is driven by the positive pressure in the telescopic groove to partially extend out of the telescopic groove, that is, the two extrusion blocks are close to each other, extruding the solidified plastic or impurities to crush or reduce them.

[0011] At this time, although the solidified plastic or impurities are crushed, the liquid plastic still cannot be discharged from the nozzle due to the obstruction of the extrusion block, and the pressure in the nozzle body is still increasing. The driving block further retracts the compressed air, causing the air pressure in the telescopic groove to continue to increase. When the air pressure in the telescopic groove is equal to or greater than the second preset value, the pressure relief structure opens, and the gas in the telescopic groove is quickly discharged through the pressure relief structure. After the telescopic groove is depressurized, the extrusion block elastically retracts under the resetting elastic force of the tension spring and the pressure relief structure is closed, that is, the two extrusion blocks are reset away from each other, and a flow channel for the liquid plastic to flow through is formed between the two extrusion blocks, so that the liquid plastic can be sprayed out through the nozzle, and the crushed solidified plastic or impurities are sprayed out together with the liquid plastic, and the dredging of the nozzle is completed.

[0012] After the liquid plastic is ejected, the pressure in the nozzle body gradually decreases until it is less than the first preset value. The drive block then elastically extends and resets under the action of the reset elastic force of the first spring. Since the air in the telescopic groove and the sliding groove is partially discharged to the outside during pressure relief, when the drive block resets, air is replenished to the telescopic groove and the sliding groove through the one-way ventilation structure to restore them, so that the nozzle can repeatedly clear the blocked mouth in subsequent use.

[0013] The above solution allows the nozzle to be unblocked in time and automatically when the nozzle is blocked and the pressure inside the nozzle body increases, greatly reducing the risk of machine damage due to excessive pressure inside the nozzle body, and no manual unblocking is required, thereby increasing safety.

[0014] Preferably, the pressure relief structure includes a receiving groove arranged in the shell wall of the nozzle body and connected with the expansion groove and the outside respectively, and a block is arranged in the receiving groove for linear elastic movement, which moves to connect the expansion groove and the receiving groove when the air pressure in the expansion groove is equal to or greater than a second preset value, and a second spring is arranged between the block and the receiving groove, which drives the block to move in the opposite direction and reset to disconnect the expansion groove and the receiving groove when the air pressure in the expansion groove is less than the second preset value, and there is sliding damping between the block and the receiving groove.

[0015] With the above solution, when the air pressure in the telescopic slot is equal to or greater than the second preset value, the block moves to connect the telescopic slot and the receiving slot, that is, the pressure relief structure is opened, and the gas in the telescopic slot is discharged to the outside after passing through the receiving slot. When the air pressure in the telescopic slot is reduced to less than the second preset value, the block elastically moves and resets under the action of the second spring to disconnect the telescopic slot and the receiving slot, that is, the pressure relief structure is closed. And because there is sliding damping between the block and the receiving slot, the block slides slowly when resetting, ensuring that the air pressure in the telescopic slot can be reduced to the point where the extrusion block can be smoothly elastically retracted and reset.

[0016] Preferably, a rotating shaft is rotatably provided on the opposite side of the two extrusion blocks, and a scraper is protruding outward from the outer ring wall of the rotating shaft. A transmission structure is provided between the nozzle body and the extrusion block to drive the rotating shaft and the scraper to rotate and scrape the solid plastic on the extrusion block when the telescopic groove is depressurized.

[0017] With the above solution, since the opposite side of the two extrusion blocks is in direct contact with the liquid plastic, the liquid plastic in the nozzle will also condense on the opposite side of the two extrusion blocks when solidified. The rotating shaft rotates, driving the scraper to rotate and scrape off the waste condensed on the opposite side of the two extrusion blocks. The gas discharged from the telescopic groove through the pressure relief structure is used as the driving force to drive the rotating shaft to rotate through the transmission structure, without the need for additional driving devices and energy, saving costs and reducing energy consumption.

[0018] Preferably, the transmission structure includes a rotating groove arranged inside the extrusion block and connected to the accommodating groove, a transmission shaft concentrically fixedly arranged on one side of the rotating shaft close to the rotating groove and sealingly rotatably connected to the rotating groove, and a driving fan blade protruding outward from the outer ring wall of the transmission shaft, a cavity is arranged inside the driving fan blade and a jet port is arranged on its side wall to connect the cavity with the outside world, a ventilation groove connected to the cavity and the rotating groove respectively is arranged in the transmission shaft, the gas discharged by pressure relief in the telescopic groove passes through the accommodating groove, the rotating groove, the ventilation groove and the cavity and is discharged through the jet port to drive the driving fan blade to rotate, and a rotating space for the driving fan blade to rotate and connected to the outside world is arranged inside the extrusion block.

[0019] With the above solution, when the accommodating groove is connected with the telescopic groove, the gas in the telescopic groove passes through the accommodating groove, the rotating groove, the venting groove and the cavity in sequence and then is ejected into the rotating space through the jet port. The rotating space is connected with the outside world, and the ejected gas can be discharged from the rotating space to the outside world. Since the accommodating groove has only this one channel connected with the outside world, and the jet port is arranged on the side wall of the driving blade, the gas can be ejected quickly through the jet port to drive the driving blade to rotate, thereby driving the transmission shaft and the rotating shaft to rotate, and the scraper rotates accordingly to scrape the material.

[0020] Preferably, a first ventilation pipe connected to the rotating groove and a second ventilation pipe connected to the rotating space are fixedly provided on the side of the extrusion block away from the scraper member, and a first connecting channel for sealingly connecting the bottom of the telescopic groove and the accommodating groove and a second connecting channel for sealingly connecting the bottom of the telescopic groove and the outside are provided in the shell wall of the nozzle body, one end of the first ventilation pipe away from the rotating groove is inserted into the first connecting channel and sealingly and slidingly cooperates with the first connecting channel, and one end of the second ventilation pipe away from the rotating space is inserted into the second connecting channel and sealingly and slidingly cooperates with the second connecting channel.

[0021] With the above solution, since the rotating groove and the rotating space are arranged in the extrusion block, and the extrusion block needs to be sealed and retracted in the telescopic groove, a first vent pipe and a first connecting channel that are sealed and plugged in and sealed and slidably matched are provided to ensure that the gas discharged from the telescopic groove after decompression enters the rotating groove after passing through the containing groove, the first connecting channel and the first vent pipe. A second vent pipe and a second connecting channel that are sealed and plugged in and sealed and slidably matched are provided to ensure that the gas in the rotating space is discharged to the outside after passing through the second vent pipe and the second connecting channel. The gas is discharged from the outer wall of the nozzle body that does not contact the mold to ensure that the gas will not affect the injection molding.

[0022] Preferably, the scraper is a scraper and the direction in which the blade is arranged is consistent with the rotation direction of the shaft.

[0023] By adopting the above solution, the scraper can not only scrape the material but also perform secondary cutting on the solidified plastic, thereby further breaking up the solidified plastic into smaller pieces, so as to facilitate its discharge along with the liquid plastic.

[0024] Preferably, cutters capable of cutting the solidified plastic are protruding from opposite sides of the two extrusion blocks.

[0025] By adopting the above scheme, a cutter is provided so that the extrusion block can cut the solidified plastic while extruding the solidified plastic. The cutting is combined with the extrusion crushing to further increase the efficiency of crushing and refining the solidified plastic or impurities.

[0026] Preferably, the one-way air supply structure is a one-way valve.

[0027] By adopting the above solution, the one-way valve can realize the function of one-way ventilation.

[0028] The present invention has significant technical effects due to the adoption of the above technical solution: When the nozzle is blocked, the pressure in the nozzle body increases, driving the drive block to retract and squeeze the air to drive the extrusion block to partially extend. The two extrusion blocks approach each other to extrude and cut the solidified plastic or impurities, breaking and refining them. When the pressure inside the expansion slot is too high, the pressure is released, the extrusion block elastically retracts, and the liquid plastic carries the broken solidified plastic or impurities out through the nozzle. The pressure inside the nozzle body decreases, and the drive block elastically extends and resets, while completing the air replenishment in the expansion slot and the sliding slot, waiting for the next use; The gas discharged from the telescopic slot passes through the containing slot, the first connecting channel, the first vent pipe, the rotating slot, the vent pipe and the cavity in turn, and then is ejected into the rotating space through the jet port. The gas ejected quickly through the jet port drives the driving blade to rotate, thereby driving the transmission shaft and the rotating shaft to rotate, and the scraper rotates accordingly to scrape and cut. The gas in the rotating space is discharged to the outside through the second vent pipe and the second connecting channel. Through the above two advantages, when the mouth of the nozzle body is blocked and the pressure inside the nozzle body increases, the mouth can be cleared in time and automatically, greatly reducing the risk of excessive pressure inside the nozzle body damaging the machine, and no manual clearing is required, which increases safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a top view of a nozzle for an injection molding machine in an embodiment; Figure 2 yes Figure 1 Sectional view at AA in the figure; Figure 3 yes Figure 2 The enlarged view of point B in the figure; Figure 4 yes Figure 3 The enlarged view of point C in the figure; Figure 5 yes Figure 4 The enlarged view of point D in the figure; Figure 6 It is a partial enlarged view of a nozzle of an injection molding machine in an embodiment when extrusion blocks are close to each other and extrusion crushes the solidified plastic; Figure 7 yes Figure 6 The enlarged view of point E in the figure; Figure 8 It is a partial enlarged view of a nozzle pressure relief structure for an injection molding machine in an embodiment when the pressure relief structure is opened and the extrusion blocks are reset away from each other; Fig. 9 yes Figure 8 The enlarged view of F in the figure; Fig.10 is a disassembled diagram of a nozzle for an injection molding machine in an embodiment; Fig.11 yes Fig.10 The enlarged view of G in the figure; Fig.12 yes Fig.11 Enlarged view of point H in the figure.

[0030] The names of the parts indicated by the numerical labels in the above drawings are as follows: 1. Nozzle body; 101. Nozzle; 2. Extrusion block; 201. Cutter; 3. Telescopic slot; 4. Tension spring; 5. Drive block; 6. Slide slot; 7. First spring; 8. Air passage; 9. Accommodation slot; 10. Connecting slot; 11. Block; 12. Second spring; 13. One-way valve; 14. Rotating shaft; 15. Scraper; 1501. Blade; 16. Rotating slot; 17. Transmission shaft; 18. Driving blade; 19. Rotating space; 20. Cavity; 21. Jet port; 22. Ventilation slot; 23. First ventilation pipe; 24. First connecting channel; 25. Second ventilation pipe; 26. Second connecting channel; 27. Circular groove. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. Example

[0032] A nozzle for an injection molding machine, referring to Figures 1 to 12 , comprising a nozzle body 1, the inner wall of the nozzle mouth 101 of the nozzle body 1 is symmetrically concavely provided with two telescopic grooves 3, an extrusion block 2 is sealed and telescopically provided in the telescopic groove 3, a circular groove 27 is concavely provided at the bottom of the telescopic groove 3, and a tension spring 4 is provided between the circular groove 27 and the extrusion block 2, with its two ends respectively fixedly connected to the bottom of the circular groove 27 and the side of the extrusion block 2 close to the circular groove 27. Under normal conditions, the tension spring 4 controls the extrusion block 2 to be completely received in the telescopic groove 3, and when the extrusion block 2 is completely received in the telescopic groove 3, its side close to the circular groove 27 abuts against the bottom of the telescopic groove 3. A cutter 201 for cutting solidified plastic is convexly provided on the opposite sides of the two extrusion blocks 2.

[0033] The inner wall of the nozzle body 1 is concavely provided with a sliding groove 6, and the shell wall of the nozzle body 1 is provided with a gas passage 8 that connects the bottom of the sliding groove 6 with the bottom of the circular groove 27. A driving block 5 is provided in a sealed and telescopic manner in the sliding groove 6, and a first spring 7 is provided between the sliding groove 6 and the driving block 5, with both ends fixedly connected to the bottom of the sliding groove 6 and the side of the extrusion block 2 close to the bottom of the sliding groove 6. Under normal conditions, the first spring 7 controls the extrusion block 2 to be located at the opening of the sliding groove 6. A one-way valve 13 is provided on the shell wall of the nozzle body 1 to control the gas flow direction so that the gas can only flow into the gas passage 8 from the outside.

[0034] A receiving groove 9 is vertically arranged in the shell wall of the nozzle body 1, and a connecting groove 10 is arranged on the side of the receiving groove 9 away from the inner wall of the nozzle body 1 to connect the receiving groove 9 with the gas passage 8. A block 11 is vertically guided and moved in the receiving groove 9, and a second spring 12 is arranged between the block 11 and the receiving groove 9, with two ends fixedly connected to the side of the receiving groove 9 away from the connecting groove 10 and the side of the block 11 away from the connecting groove 10 respectively. Under normal conditions, the second spring 12 controls the side of the block 11 close to the connecting groove 10 to seal and abut against the side of the receiving groove 9 close to the connecting groove 10, that is, the block 11 seals and blocks the connecting groove 10, so that the gas passage 8 and the receiving groove 9 are not connected. In this embodiment, the block 11 is a rectangular block, and the receiving groove 9 is a rectangular groove. Among the four side walls of the block 11, two opposite side walls are in contact with the inner wall of the receiving groove 9, and there is sliding damping; there is a gap between the remaining two side walls and the inner wall of the receiving groove 9 for gas to pass.

[0035] A first connecting channel 24 is provided in the shell wall of the nozzle body 1, and its two ends are respectively connected to the side of the accommodating groove 9 away from the connecting groove 10 and the bottom of the telescopic groove 3. A rotating groove 16 is provided in the extrusion block 2. A first ventilation pipe 23 connected to the rotating groove 16 is fixedly provided on the side of the extrusion block 2 close to the circular groove 27. The end of the first ventilation pipe 23 away from the extrusion block 2 is inserted into the first connecting channel 24 and is sealed and slidably matched with the first connecting channel 24.

[0036] A rotating shaft 14 is rotatably provided on one side of the extrusion block 2 away from the circular groove 27, and a scraper 15 is convexly provided on the outer ring wall of the rotating shaft 14. In this embodiment, the scraper 15 is a scraper, and the blade 1501 of the scraper is arranged in the same direction as the rotation direction of the rotating shaft 14. A transmission shaft 17 is coaxially fixedly provided on one side of the rotating shaft 14 close to the rotating groove 16, and one end of the transmission shaft 17 away from the rotating shaft 14 is inserted into the rotating groove 16 and is sealed and rotatably connected with the rotating groove 16. The rotating shaft 14 and the transmission shaft 17 are integrally formed.

[0037] The outer ring wall of the transmission shaft 17 is provided with a driving blade 18 protruding outward, and the driving blade 18 is hollow inside to form a cavity 20. The transmission shaft 17 is provided with a ventilation groove 22 at both ends of which are connected to the rotation groove 16 and the cavity 20 respectively, and the side wall of the driving blade 18 is provided with an air jet 21 that connects the cavity 20 with the outside. The jet direction of the air jet 21 is opposite to the rotation direction of the transmission shaft 17 and the rotating shaft 14. A rotating space 19 for the driving blade 18 to rotate is provided inside the extrusion block 2.

[0038] A second connecting channel 26 is provided in the shell wall of the nozzle body 1, and its two ends are respectively connected to the bottom of the telescopic groove 3 and the outside world. A second ventilation pipe 25 connected to the rotating space 19 is fixedly provided on one side of the extrusion block 2 close to the circular groove 27. The end of the second ventilation pipe 25 away from the extrusion block 2 is inserted into the second connecting channel 26 and is sealed and slidably matched with the second connecting channel 26.

[0039] When the injection molding machine is running, the liquid plastic is transferred to the nozzle body 1. At this time, if the nozzle 101 is not blocked, the liquid plastic can be ejected smoothly through the nozzle 101, and the pressure in the nozzle body 1 is always less than the first preset value. If the nozzle 101 is blocked, it needs to be unblocked. The unblocking process is as follows: The nozzle 101 is blocked, and the liquid plastic cannot be ejected through the nozzle 101, while the liquid plastic is still being continuously transmitted to the nozzle body 1, so that the pressure in the nozzle body 1 continues to increase until it is equal to or greater than the first preset value. At this time, the driving block 5 is sealed and retracted under the pressure of the liquid plastic, and the first spring 7 is squeezed to generate a reset elastic force. Since the sliding groove 6 and the telescopic groove 3 are connected through the air passage 8, the air inside the three is compressed and the air pressure continues to increase. The extrusion block 2 is driven by the positive pressure in the telescopic groove 3 to seal and partially extend out of the telescopic groove 3, that is, the two extrusion blocks 2 are close to each other, extruding and cutting the solidified plastic or impurities, crushing, compressing or shredding them. At this time, the tension spring 4 is stretched to generate a reset elastic force.

[0040] Until the two extrusion blocks 2 can no longer approach each other, at this time, because the two extrusion blocks 2 and the crushed solidified plastic or impurities block the nozzle 101 together, the liquid plastic still cannot be discharged from the nozzle 101, and the pressure in the nozzle body 1 is still increasing. The driving block 5 further retracts the compressed air so that the air pressure in the telescopic groove 3 continues to increase. When the air pressure in the telescopic groove 3 is equal to or greater than the second preset value, the blocking block 11 moves away from the connecting groove 10 and no longer blocks the connecting groove 10, that is, the air passage 8 and the containing groove 9 are connected through the connecting groove 10, and the gas in the telescopic groove 3, the sliding groove 6 and the air passage 8 is discharged into the containing groove 9 through the connecting groove 10, and then passes through the first connecting channel 24, the first vent pipe 23, the rotating groove 16, the vent groove 22 and the cavity 20 in sequence, and then is quickly discharged into the rotating space 19 through the jet port 21, driving the driving blade 18 to rotate, driving the transmission shaft 17, the rotating shaft 14 and the scraper to rotate, and further cutting and crushing the solidified plastic or impurities. The gas in the rotating space 19 is discharged to the outside through the second ventilation pipe 25 and the second connecting channel 26. In the above process, the second spring 12 is squeezed to generate a restoring elastic force.

[0041] As the gas in the expansion groove 3 is continuously discharged, the air pressure in the expansion groove 3 gradually decreases. After decreasing to less than the second preset value, the block 11 moves close to the connecting groove 10 under the reset force of the second spring 12. However, due to the sliding damping between the block 11 and the accommodating groove 9, the block 11 moves relatively slowly, that is, the gas in the expansion groove 3 is still continuously discharged outward, and the air pressure in the expansion groove 3 continues to decrease, so that the extrusion block 2 retracts to be completely received in the expansion groove 3 under the reset force of the tension spring 4. At the same time, the scraper is still rotating to scrape off the solidified plastic or impurities on the side of the extrusion block 2 away from the circular groove 27, reducing or avoiding the solidified plastic or impurities adhering to and accumulating on the side of the extrusion block 2 away from the circular groove 27, resulting in incomplete dredging of the mouth 101, affecting the final dredging result. During this process, the driving block 5 is still driven to retract continuously by the pressure inside the nozzle body 1. Due to the increasing elastic force of the first spring 7, the driving block 5 retracts a small distance, and since the air passage 8 is connected to the receiving groove 9, the air squeezed by the driving block 5 during the retraction will also be discharged into the receiving groove 9 through the connecting groove 10, without affecting the retraction of the extrusion block 2. After the extrusion block 2 retracts, the blocking block 11 moves to block the connecting groove 10, so that the air passage 8 is no longer connected to the receiving groove 9.

[0042] After the extrusion block 2 retracts, the liquid plastic can be ejected through the nozzle 101, and the crushed solidified plastic or impurities are ejected together with the liquid plastic, and the nozzle 101 is unblocked. After the liquid plastic is ejected, the pressure in the nozzle body 1 gradually decreases until it is less than the first preset value, and the drive block 5 elastically extends and resets under the reset elastic force of the first spring 7. Since the air in the telescopic groove 3 and the sliding groove 6 is partially discharged to the outside when the pressure is released, when the drive block 5 is reset, the telescopic groove 3, the sliding groove 6 and the air passage 8 are replenished with air through the one-way valve 13 to restore, so that the nozzle can be repeatedly unblocked when the nozzle 101 is blocked again in the future.

[0043] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A nozzle for an injection molding machine, comprising a nozzle body (1), wherein the inner wall of a nozzle opening (101) of the nozzle body (1) is symmetrically telescopically provided with two extrusion blocks (2) which can move closer to each other to crush the solidified plastic blocking the nozzle opening (101) when partially extended and move away from each other to reset when retracted, wherein the movement of the two extrusion blocks (2) is controlled by a driving structure, and characterized in that: The driving structure comprises a telescopic groove (3) recessed in the inner wall of the nozzle (101) for sealing and elastically extending the extrusion block (2), and a sliding groove (6) recessed in the inner wall of the nozzle body (1) and connected to the telescopic groove (3). The sliding groove (6) is provided with a driving block (5) which elastically retracts and squeezes air to drive the extrusion block (2) to partially extend when the nozzle (101) is blocked and the pressure in the nozzle body (1) increases to a value equal to or greater than a first preset value. The shell wall of the nozzle body (1) is provided with a pressure relief device which releases pressure when the air pressure in the telescopic groove (3) is equal to or greater than a second preset value and releases pressure when the air pressure in the telescopic groove (3) is increased. A pressure relief structure is provided which closes when the pressure decreases to less than a second preset value; a tension spring (4) is provided between the telescopic groove (3) and the extrusion block (2) for driving the extrusion block (2) to retract and reset after the pressure in the telescopic groove (3) is released; a first spring (7) is provided between the sliding groove (6) and the driving block (5) for driving the driving block (5) to extend and reset when the liquid plastic carrying the broken solidified plastic is ejected from the nozzle opening (101) so that the pressure inside the nozzle body (1) decreases to less than the first preset value; and a one-way air replenishment structure is provided on the shell wall of the nozzle body (1) for replenishing air into the telescopic groove (3) and the sliding groove (6) when the driving block (5) is reset.

2. A nozzle for an injection molding machine according to claim 1, characterized in that: The pressure relief structure comprises a receiving groove (9) arranged in the shell wall of the nozzle body (1) and respectively connected with the telescopic groove (3) and the outside world; a block (11) is arranged in the receiving groove (9) for linear elastic movement and moves to connect the telescopic groove (3) and the receiving groove (9) when the air pressure in the telescopic groove (3) is equal to or greater than a second preset value; a second spring (12) is arranged between the block (11) and the receiving groove (9) and drives the block (11) to move in the opposite direction and reset to disconnect the telescopic groove (3) and the receiving groove (9) when the air pressure in the telescopic groove (3) is less than the second preset value; and sliding damping exists between the block (11) and the receiving groove (9).

3. A nozzle for an injection molding machine according to claim 2, characterized in that: A rotating shaft (14) is rotatably provided on one side opposite to the two extrusion blocks (2), a scraper (15) is protruding outwardly from the outer ring wall of the rotating shaft (14), and a transmission structure is provided between the nozzle body (1) and the extrusion block (2) to drive the rotating shaft (14) and the scraper (15) to rotate and scrape off the solid plastic on the extrusion block (2) when the telescopic groove (3) releases pressure.

4. A nozzle for an injection molding machine according to claim 3, characterized in that: The transmission structure comprises a rotating groove (16) arranged inside the extrusion block (2) and connected to the containing groove (9), a transmission shaft (17) arranged coaxially and fixedly on one side of the rotating shaft (14) close to the rotating groove (16) and connected to the rotating groove (16) in a sealed rotational manner, and a driving blade (18) protruding outwardly from the outer ring wall of the driving shaft (17), wherein a cavity (20) is arranged inside the driving blade (18) and a hole is arranged on the side wall thereof to connect the cavity (20) to the outside. The transmission shaft (17) is provided with a venting groove (22) which is respectively connected with the cavity (20) and the rotating groove (16); the gas discharged from the telescopic groove (3) passes through the containing groove (9), the rotating groove (16), the venting groove (22) and the cavity (20) and then is discharged through the venting groove (21) to drive the driving blade (18) to rotate; and a rotating space (19) for driving the driving blade (18) to rotate and which is connected with the outside is provided inside the extrusion block (2).

5. A nozzle for an injection molding machine according to claim 4, characterized in that: A first vent pipe (23) communicating with the rotating groove (16) and a second vent pipe (25) communicating with the rotating space (19) are fixedly arranged on the side of the extrusion block (2) away from the scraper (15); a first connecting channel (24) for sealingly connecting the bottom of the telescopic groove (3) and the accommodating groove (9) and a second connecting channel (26) for sealingly connecting the bottom of the telescopic groove (3) and the outside are arranged in the shell wall of the nozzle body (1); an end of the first vent pipe (23) away from the rotating groove (16) is inserted into the first connecting channel (24) and is sealingly and slidably matched with the first connecting channel (24); an end of the second vent pipe (25) away from the rotating space (19) is inserted into the second connecting channel (26) and is sealingly and slidably matched with the second connecting channel (26).

6. A nozzle for an injection molding machine according to claim 3, characterized in that: The scraping member (15) is a scraper and the direction in which the blade (1501) is arranged is consistent with the rotation direction of the rotating shaft (14).

7. A nozzle for an injection molding machine according to claim 1, characterized in that: A cutter (201) capable of cutting the solidified plastic is protruded from opposite sides of the two extrusion blocks (2).

8. A nozzle for an injection molding machine according to claim 1, characterized in that: The one-way air supply structure is a one-way valve (13).

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