Micro precision plunger screw

Abstract

The utility model relates to a micro precise plunger screw rod, which comprises a material pipe, a plunger cylinder coaxially fixed at the front end of the material pipe, a nozzle coaxially fixed at the front end of the plunger cylinder, a screw rod arranged in the material pipe along the axis and a plunger screw rod head fixed at the top end of the screw rod, the front end of the plunger screw head is provided with a plunger sealing part, the outer diameter of the plunger sealing part is matched with that of a plunger cylinder sealing channel, and the outer diameter of the plunger sealing part is smaller than that of the screw. The injection mold has the advantages of reducing the injection weight, realizing precise injection, increasing the injection pressure, reducing the retention time of materials, reducing the carbonization and degradation phenomena of the materials, improving the quality of the injected materials and the like, and is suitable for injection molding of trace materials.

Description

Technical Field

[0001] The utility model relates to the technical field of injection molding, in particular to a micro-precision plunger screw. Background Art

[0002] Injection molding is an extremely important part of modern industry. It is a method of stirring completely molten plastic material through a screw at a certain temperature, injecting it into a mold cavity with high pressure, and obtaining a molded product after cooling and solidification. As contemporary industrial products become more and more refined, the miniaturization and refinement of injection molding are also becoming more and more demanding. At present, the improvement of miniaturization in the injection molding process is mainly reflected in the use of screws with smaller diameters. However, in order to ensure the effective aspect ratio of the screw, the diameter of the screw cannot be very thin, because the thinner the screw, the higher the possibility of it being twisted off during operation. In actual applications, the inner diameter of the material barrel is generally not less than 14mm. However, the screw under this parameter still cannot meet the needs of miniaturization well. In addition, it is difficult for existing screws to control the injection volume of molten plastic, that is, it cannot meet the needs of precision.

[0003] Therefore, there is an urgent need in this field for a screw that can simultaneously meet the requirements of miniaturization and precision. Utility Model Content

[0004] The purpose of the utility model is to provide a micro-precision plunger screw in order to overcome the defects of the prior art.

[0005] In order to achieve the purpose of the present invention, the present application provides the following technical solutions.

[0006] In the first aspect, the present application provides the plunger screw comprising a material pipe, a plunger cylinder coaxially fixed to the front end of the material pipe, a nozzle coaxially fixed to the front end of the plunger cylinder, a screw installed inside the material pipe along the axis, and a plunger screw head fixed to the top end of the screw, wherein a plunger sealing channel is provided at the axis of the plunger cylinder, and a plunger sealing portion with an outer diameter matching the plunger sealing channel is provided at the front end of the plunger screw head, and the outer diameter of the plunger sealing portion is smaller than the outer diameter of the screw. In the present utility model, a plunger screw head group is provided at the front end of the screw, and a plunger structure is formed by the plunger screw head group and the plunger cylinder, so that the extrusion amount of the material can be controlled by controlling the stroke of the plunger screw head group, thereby achieving the purpose of precision injection molding. That is, a screw is used to melt, compress, and convey plastic, and the plunger screw head at the front end of the screw is used to realize the functions of fine sealing and precision injection, thereby achieving the function of precision micro-injection. In addition, since the plunger screw head assembly in this device is only responsible for squeezing the material forward (similar to the role of a piston), there is no possibility of it being twisted off, so a smaller diameter plunger screw head can be used to achieve the purpose of microinjection.

[0007] In one embodiment of the first aspect, the plunger screw head includes a connecting thread and a plunger sealing portion in sequence from the rear end to the front end, and the connecting thread is fixed to the front end of the screw.

[0008] In one embodiment of the first aspect, a weight-reducing portion is provided at the top of the plunger screw head, the head of the weight-reducing portion is conical, the rest of the weight-reducing portion is cylindrical, and the outer diameter of the weight-reducing portion is smaller than the outer diameter of the plunger sealing portion. As is well known, in the field of injection molding screws, the cross-sectional area of ​​the screw is inversely proportional to the injection pressure, and the cross-sectional area of ​​the screw is proportional to the injection weight. In the present application, there are two purposes for setting the weight-reducing portion. The first is to reduce the weight of the injection molding to achieve the purpose of lightweighting, reduce the residence time of the material in the material pipe, and reduce the occurrence of carbonization. The purpose of setting the plunger sealing portion is first to fine-seal the sealant, and second to increase the injection pressure.

[0009] In one embodiment of the first aspect, the plunger screw includes a meson and a check ring, wherein the meson is fixed to the outside of the plunger screw head, the check ring is sleeved on the outside of the plunger screw head, and the outer diameter of the check ring matches the inner diameter of the material pipe, and the check ring is located at the front end of the meson.

[0010] In one embodiment of the first aspect, a guide portion, a sealing portion and a guide groove portion are sequentially provided between the connecting thread of the plunger screw head and the plunger sealing portion, wherein the meson is fixed on the outside of the guide portion, the check ring is sleeved on the outside of the sealing portion, and the outer diameter of the meson and the outer diameter of the tail end of the guide groove portion are both smaller than the outer diameter of the check ring but larger than the inner diameter of the check ring.

[0011] In one embodiment of the first aspect, the plunger cylinder is hollow along the axial direction, and a glue passage is provided inside the plunger cylinder, the middle part of the glue passage is a plunger sealing channel, and the inner wall of the front end of the glue passage is provided with a nozzle thread, and the nozzle is fixed to the front end of the glue passage by the nozzle thread, and the inner diameter of the tail end of the glue passage is the same as the inner diameter of the material pipe, and abuts against the front end of the material pipe.

[0012] In one implementation of the first aspect, an axial length of the plunger sealing channel in the plunger cylinder is greater than an axial length of the plunger sealing portion.

[0013] In one embodiment of the first aspect, the nozzle is through-hole along its axial direction, and the inner diameter of the tail end of the nozzle is the same as the inner diameter of the plunger sealing channel, and the small hole at the front end of the nozzle is through-hole in the nozzle, and the inner diameter is smaller than the inner diameter of the middle hole in the nozzle.

[0014] In one embodiment of the first aspect, a driving unit is connected to the tail end of the screw, and the driving unit is used to drive the entire screw to rotate, discharge materials, and move back and forth along the material pipe.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] (1) The plunger structure is formed by the plunger screw head group and the plunger cylinder, so that the extrusion amount of the material can be controlled by controlling the stroke of the plunger screw head group to achieve the purpose of precision injection molding;

[0017] (2) A smaller diameter plunger screw head can be used to achieve the purpose of microinjection;

[0018] (3) Micro-precision plunger screw can reduce the weight of the injected plastic;

[0019] (4) It can increase the injection pressure of plastic;

[0020] (5) Reduce the residence time of plastic in the material pipe to reduce the occurrence of carbonization. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the overall assembly diagram of the micro-precision plunger screw in Example 1;

[0022] Figure 2 Schematic diagram of the structure of the material pipe in Example 1;

[0023] Figure 3 Schematic diagram of the structure of the screw in Example 1;

[0024] Figure 4 Schematic diagram of the structure of the plunger screw head in Example 1;

[0025] Figure 5 for Figure 4 Schematic diagram of the cross-sectional structure of AA;

[0026] Figure 6 This is a schematic structural diagram of the reverse loop in Example 1;

[0027] Figure 7 This is a schematic structural diagram of the meson in Example 1;

[0028] Figure 8 Schematic diagram of the structure of the plunger cylinder in Example 1;

[0029] Figure 9 Schematic diagram of the structure of the nozzle in Example 1;

[0030] Figure 10 This is an enlarged schematic diagram of the local state of the plunger screw head assembly during glue injection;

[0031] Figure 11 This is an enlarged schematic diagram of the local state of the plunger screw head assembly at the beginning of injection molding;

[0032] Figure 12 This is an enlarged schematic diagram of the local state of the plunger screw head assembly when the screw continues to push forward;

[0033] Figure 13 This is an enlarged schematic diagram of the local state of the plunger screw head assembly when the screw restarts to feed glue;

[0034] Figure 14 This is a schematic structural diagram of the micro-precision plunger screw of Example 2 when assembled at the top of the screw;

[0035] Figure 15 Schematic diagram of the structure of the plunger screw head in Example 2;

[0036] Figure 16 This is a schematic diagram of the partial structure of the top end of the screw in Example 2;

[0037] Figure 17 This is a schematic diagram of the structure of the marbles when sealing with glue in Example 2;

[0038] Figure 18 Schematic diagram of the side cross-section structure of the fork-type check ring in Example 3;

[0039] Figure 19 This is a schematic diagram of the main structure of the fork-type check ring in Example 3;

[0040] Figure 20 This is the overall assembly diagram of the micro-precision plunger screw in Example 4;

[0041] Figure 21 Schematic diagram of the structure of the nozzle in Example 4.

[0042] In the accompanying drawings, 1 is a nozzle, 11 is a connecting screw, 12 is a glue injection channel, 2 is a material pipe, 21 is a feed port, 22 is a material pipe end hole, 3 is a screw, 31 is a feeding section, 32 is a compression section, 33 is a metering section, 4 is a plunger screw head, 41 is a weight reduction section, 42 is a plunger sealing section, 43 is a guide groove section, 431 is a guide groove, 44 is a sealing section, 45 is a guide section, 46 is a connecting screw, 5 is a check ring , 51 is the check part, 52 is the fork-shaped part, 6 is the meson, 7 is the plunger cylinder, 71 is the connecting channel, 72 is the plunger sealing channel, 73 is the mounting screw hole, 8 is the plunger unit, 81 is the weight reduction part, 82 is the plunger sealing part, 83 is the second feed channel, 84 is the mounting cavity, 9 is the connected check ring, 91 is the first feed channel, 92 is the accommodating cavity, 93 is the connecting screw thread, 94 is the external thread, and 10 is the marble. DETAILED DESCRIPTION

[0043] Unless otherwise defined, technical or scientific terms used in this specification and claims shall have the ordinary meanings understood by persons having ordinary skill in the art to which this invention belongs. All numerical values ​​listed herein, from the lowest value to the highest value, refer to all numerical values ​​obtained by incrementing the lowest value to the highest value by one unit when the difference between the lowest value and the highest value is two units or more.

[0044] The following describes specific embodiments of the present invention. It should be noted that, in the context of describing these embodiments, for the sake of brevity and clarity, this specification does not exhaustively describe all features of the actual embodiments. Those skilled in the art may modify and replace the embodiments of the present invention without departing from the spirit and scope of the present invention, and the resulting embodiments are also within the scope of protection of the present invention.

[0045] Example

[0046] The following is a detailed description of an embodiment of the present invention. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process. However, the protection scope of the present invention is not limited to the following embodiment.

[0047] Example 1

[0048] A micro-precision plunger screw, the assembly diagram of which is as follows Figure 1 As shown, it includes a material pipe 2, a screw 3, a plunger screw head 4, a check ring 5, a meson 6, a plunger cylinder 7, a nozzle 1, a driving device (not shown in the figure), etc., wherein the screw 3 is coaxially installed in the material pipe 2, the plunger cylinder 7 is fixedly installed on the top of the material pipe 2 by bolts, and the nozzle 1 is fixedly installed on the top of the plunger cylinder 7 by bolts. The plunger screw head 4 is coaxially fixedly installed on the top of the material pipe 2, and its main part is inserted into the plunger cylinder 7. The meson 6 is fixedly installed on the outside of the plunger screw head 4, and the check ring 5 is sleeved on the outside of the plunger screw head 4, and the outer diameter of the check ring 5 is ground with a small gap with the inner wall of the material pipe 2. The driving device is installed at the tail end of the screw 3, and is used to drive the screw 3 to rotate as a whole, move forward or backward. The specific structure of each component is as follows.

[0049] The structure of the material pipe 2 is as follows Figure 2 As shown, its structure is not much different from the existing material pipe, including a material pipe hole 22 that runs through the axial direction for mounting the screw 3, and a feed port 21 is opened on the rear end wall of the material pipe 2. A heating device can be installed on the outer wall of the material pipe 2 to melt the material. The structure of the screw 3 is as shown in FIG. Figure 3As shown, its shape is not much different from that of an ordinary screw, and it includes, from front to back, a metering section 33, a compression section 32, and a feeding section 31. However, in this application, the outer diameter of the screw 3 is relatively thin, and the effective aspect ratio can be set to 14 to 22:1. The inner diameter of the material tube 2 used is 14 mm, which is used for micro-injection molding. Of course, the diameter of the screw 3 between 14 and 30 mm can basically achieve micro-injection molding. The smaller the diameter, the smaller the injection volume.

[0050] The structure of the plunger screw head 4 is as follows Figure 4 As shown, it includes a weight-reducing portion 41, a plunger sealing portion 42, a guide groove portion 43, a sealing portion 44, a guide portion 45 and a connecting screw 46 from the front end (i.e., the left end) to the rear end (i.e., the right end). The connecting screw 46 is inserted into the center of the front end of the screw 3 and fixes the plunger screw head 4 and the screw 3 through the thread. Figure 7 The meson 6 is fixed to the outside of the guide portion 45, and the two are fixed by screw connection. The structure of the guide groove portion 43 is as follows Figure 5 As mentioned above, four guide grooves 431 are provided on the periphery for glue application. Figure 6 The illustrated check ring 5 is sleeved outside the sealing portion 44, and the axial length of the sealing portion 44 is greater than that of the check ring 5. Specifically, the check ring 5 and the plunger screw head 4 are positioned such that the front end face of the check ring 5 abuts the rear end face of the guide groove 43, and the rear end face of the check ring 5 abuts the front end face of the meson 6. The plunger seal 42 is cylindrical, with a conical structure at its connection with the guide groove 43. The outer diameter of the plunger seal 42 is smaller than the diameter of the screw 3. The diameter of the plunger seal is most preferably 1D to 12D, with a second preferred range of 12.1D to 22D. Of course, it can also be 22.1D to 500D. As long as it is smaller than the screw diameter, the weight reduction and pressure increase function can be achieved. However, it should be noted that the ratio of the plunger seal diameter to the screw diameter is between 0.2 and 0.9, which is reasonable and scientific, and preferably 0.5 to 0.9. However, since this embodiment is used for micro-injection, a large diameter is not suitable. For example, in this application, it can be made into 6 to 12 mm. In this embodiment, it is set to 8 mm. In order to further reduce the volume and weight of the plastic in the metering chamber and increase the injection pressure of the material, the weight-reducing portion 41 adopts a cylindrical structure with a smaller diameter. Its head is conical, and its connection with the plunger sealing portion 42 also adopts a conical connection. In this embodiment, the outer diameter of the weight-reducing portion 41 is set to 6 mm.

[0051] The structure of the plunger cylinder 7 is as follows Figure 8As shown, its structure is similar to the flange in a conventional screw assembly. Its outer circumference is provided with a circle of flange screw holes and is fixed to the front end of the material pipe 2 by a number of bolts. A through channel is provided at the axis of the plunger cylinder 7. From the front end to the rear end, there is a mounting screw hole 73, a plunger sealing channel 72, and a connecting channel 71. The inner diameter of the connecting channel 71 is the same as the inner diameter of the material pipe 2, and they are seamlessly connected. The inner diameter of the plunger sealing channel 72 is precisely ground to the outer diameter of the plunger sealing portion 42, but relative sliding can occur between the two. A tapered surface also exists between the plunger sealing channel 72 and the connecting channel 71, and its taper is the same as the taper at the connection between the plunger sealing portion 42 and the guide groove portion 43. The axial length of the plunger cylinder plunger sealing channel 72 is greater than the axial length of the plunger sealing portion 42. The inner wall of the mounting screw hole 73 is provided with a nozzle thread, and the nozzle 1 is fixedly mounted in the mounting channel 73.

[0052] The structure of the nozzle 1 is as follows Figure 9 As shown, a material channel is also provided at its axis, which is connected front to back, and the inner diameter of the rear end material channel is the same as the inner diameter of the plunger sealing channel 72, and the two are connected to each other without any gap.

[0053] The working principle of the micro-precision plunger screw described in this embodiment is as follows. Figure 10 ~Attached Figure 13 Conduct the demonstration process.

[0054] During injection, as the screw rotates, the molten material flows forward. At this time, the check ring 5 is located at the front end, that is, the front end of the check ring 5 abuts against the tail end of the guide groove 43, and the plunger sealing portion 42 is not inserted into the plunger sealing channel 72. Figure 10 As shown in the figure, the material flows along the following path: gap between screw 3 and the inner wall of pipe 2 → gap between pion 6 and the inner wall of pipe 2 → gap between the inner wall of check ring 5 and the outer wall of sealing portion 44 → guide groove 431 → passage of plunger cylinder 7 → passage of nozzle 1. Because the mold and nozzle are in contact, the cold glue port in the mold prevents material from flowing out of the front end of nozzle 1. Consequently, the material is gradually stored in the passage of nozzle 1. As the stored material fills the passages of nozzle 1 and plunger cylinder 7, continued feeding increases the volume of the material in the metering chamber, generating a reverse thrust that causes screw 3 and plunger screw head 4 to gradually retract.

[0055] When the injection molding starts, the outlet at the front end of the nozzle 1 is opened first, and then the screw 3 is pushed forward by the driving device. At this time, the screw 3, the entire plunger screw head 4 and the meson 6 will move forward. Since the check ring 5 is only sleeved on the outside of the sealing portion 44, that is, it is not fixed, the check ring 5 will not move forward at this time until the front end of the meson 6 on the plunger screw head 4 abuts against the rear end of the check ring 5. Figure 11In this way, the check ring 5 and the meson 6 cut off the flow channel of the molten material, that is, the new material cannot flow forward, and the material originally stored in the nozzle 1 and the plunger cylinder 7 cannot flow backward, which has a sealing effect.

[0056] The driving device drives the screw 3 to continue to move forward. At this time, the screw 3, the plunger screw head 4, the check ring 5, and the meson 6 will move forward together until the plunger sealing portion 42 enters the plunger sealing channel 72. Figure 12 As shown in the figure, due to the small tolerance between the plunger seal 42 and the plunger seal channel 72, a structure similar to that of a syringe and a piston is formed. As the screw 3 continues to advance, the plunger seal 42 pushes the material forward, ejecting it from the nozzle. Because the diameter of the plunger seal channel 72 is fixed, the injection volume of the material can be precisely controlled by simply controlling the advancement length of the plunger seal 42 (i.e., the stroke of the screw 3).

[0057] When the injection molding is completed, the melt driving device starts to rotate, and the material is pushed from the discharge port to the metering chamber by the thrust generated by the screw edge angle. When the material is pushed to the tail end of the check ring, the material pushes the check ring forward until the front end of the check ring 5 abuts against the tail end of the guide groove 43. In this way, the flow channel of the molten material is reopened. Figure 13 As the volume of the material in the metering chamber does not increase and the material cannot flow out of the front hole of the nozzle, the material will generate a reverse thrust, pushing the plunger screw assembly to continue moving backward until the plunger sealing portion 42 is completely pulled out of the plunger sealing channel 72, and then it returns to the state shown in FIG. Figure 10 In the state shown, you can continue with the next injection.

[0058] Example 2

[0059] In this embodiment, the structure of the material pipe, plunger cylinder, screw and nozzle is the same as that of embodiment 1, and the plunger screw head adopts a marble plunger screw head, and its structure is as follows: Figure 14 and Figure 17 As shown, it mainly includes three parts, namely the plunger unit 8, the conjoined check ring 9 and the marble 10, wherein the plunger unit 8 is as shown in FIG. Figure 15 As shown, the conjoined check ring 9 is as shown Figure 16 As shown, the details are as follows:

[0060] The front end of the plunger unit 8 is provided with a weight-reducing portion 81 and a plunger sealing portion 82, respectively. These two structures are the same as those in Example 1, and their cooperation principles with the plunger cylinder are also the same. However, in this embodiment, a mounting cavity 84 is provided at the rear end of the plunger unit. The front end of this mounting cavity 84 is provided with multiple second material transfer channels 83 extending from the inside to the outside, and the inner wall of the mounting cavity 84 is threaded.

[0061] The front end of the one-piece check ring 9 is provided with a housing chamber 92 at its axis. The inner wall of the rear end of the housing chamber 92 is spherical and has a first material transfer channel 91 extending from the inside to the outside. The inner diameter of the middle portion of the housing chamber 92 is constant, while the diameter of the opening at the front end of the housing chamber 92 increases. The front end of the one-piece check ring 9 is provided with an external thread 94 on its outer wall. This external thread 94 matches the internal thread on the inner wall of the mounting cavity 84, thereby threading the plunger unit 8 to the one-piece check ring 9. A marble 10 is located within the housing chamber 92, and its diameter is the same as that of the inner wall at the rear end of the housing chamber 92. The rear end of the one-piece check ring 9 is provided with a connecting thread 93, which is fixed to the front end axis of the screw rod via the connecting thread 93.

[0062] The cooperation between the plunger unit 8 (especially the weight reduction portion 81 and the plunger sealing portion 82) and the plunger cylinder in this embodiment is consistent with that in embodiment 1 and will not be repeated here, but the form of glue injection and rear end sealing is completely different from that in embodiment 1, as follows.

[0063] The material is conveyed by the screw and enters the accommodating chamber 92 from the first feeding channel 91, and pushes the marble 10 to roll forward until the marble 10 reaches the front end of the accommodating chamber 92. The material enters the installation cavity 84, and then flows through the second feeding channel 83 and enters the plunger cylinder. This is the state of the entire material storage. Figure 14 shown.

[0064] When the driving device starts to push the screw forward, the material will generate a reverse thrust, the material passes through the second feeding channel 83, and pushes the marble 10 back until it abuts against the inner wall of the tail end of the accommodating cavity 92. In this way, the marble 10 blocks all the first feeding channels 91, forming a sealed state, such as Figure 17 The subsequent injection molding process is the same as that in Example 1 and will not be described again here.

[0065] Example 3

[0066] In this embodiment, a structure similar to that of embodiment 1 is adopted, except that: in this embodiment, the check ring is replaced with Figure 18 、 Figure 19 The fork-type check ring shown in the figure includes a check portion 51 and a fork-shaped portion 52. During installation, the check portion 51 is sleeved outside the sealing portion of the plunger screw head, while the fork-shaped portion 52 is inserted into the guide groove of the plunger screw head. Therefore, the rotation of the guide groove can drive the rotation of the fork-type check ring. That is, when the screw rotates, it drives the plunger screw head to rotate synchronously, and also drives the entire fork-type check ring to rotate synchronously.

[0067] The ordinary ring-type check ring (the check ring used in Example 1) is replaced with a fork-type check ring because the fork-type check ring rotates and stops synchronously with the screw each time, so each time the check ring retreats and contacts the meson, it is at the same position, which can achieve better sealing repeatability accuracy. The fork-type check ring rotates synchronously with the screw head and there is no relative friction motion, so the fork-type check ring will not suffer mechanical wear from the screw head, so this embodiment makes improvements.

[0068] Example 4

[0069] In this embodiment, the plunger cylinder and the nozzle are combined into a whole, and the assembly diagram is shown in FIG. Figure 20 As shown, the structure of the nozzle is as follows Figure 21 As shown. In this embodiment, a connecting thread 11 is provided on the outer side of the tail end of the nozzle 1, and is directly fixed to the top end of the material tube 2 through the connecting thread 11. A continuous glue injection channel 12 is provided at the axis of the nozzle 1. In this embodiment, the tail end of the glue injection channel 12 is interconnected with the channel in the material tube 2, and the front end inner diameter of the glue injection channel 12 remains unchanged, and is ground with a small gap with the plunger seal in the plunger screw head 4, that is, the glue injection channel in the nozzle 1 and the plunger seal in the plunger screw head 4 form a glue sealing structure. The rest of the structure and operating principle of this embodiment are similar to those of Example 1 and will not be repeated here.

[0070] The above description of the embodiments is intended to facilitate understanding and application of the present application by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without expending any creative effort. Therefore, the present application is not limited to the embodiments described herein, and improvements and modifications made by those skilled in the art based on the disclosure of this application without departing from the scope and spirit of this application are within the scope of this application.

Claims

1. A micro-precision plunger screw, characterized in that: The plunger screw includes a material pipe, a plunger cylinder coaxially fixed to the front end of the material pipe, a nozzle coaxially fixed to the front end of the plunger cylinder, a screw installed inside the material pipe along the axis, and a plunger screw head fixed to the top end of the screw, wherein a plunger sealing channel is provided at the axis center of the plunger cylinder, and a plunger sealing portion with an outer diameter matching the plunger sealing channel is provided at the front end of the plunger screw head, and the outer diameter of the plunger sealing portion is smaller than the outer diameter of the screw.

2. The micro-precision plunger screw according to claim 1, characterized in that: The plunger screw head includes a connecting thread and a plunger sealing portion in sequence from the rear end to the front end, and the connecting thread is fixed to the front end of the screw.

3. The micro-precision plunger screw according to claim 2, characterized in that: A weight-reducing portion is provided at the top end of the plunger screw head. The head of the weight-reducing portion is conical, and the rest of the weight-reducing portion is cylindrical. The outer diameter of the weight-reducing portion is smaller than the outer diameter of the plunger sealing portion.

4. The micro-precision plunger screw according to claim 1, characterized in that: The plunger screw includes a meson and a check ring, wherein the meson is fixed on the outside of the plunger screw head guide part, the check ring is sleeved on the outside of the plunger screw head, and the outer diameter of the check ring matches the inner diameter of the material tube, and the check ring is located at the front end of the meson.

5. The micro-precision plunger screw according to claim 4, characterized in that: A guide portion, a sealing portion and a guide groove portion are sequentially provided between the connecting thread of the plunger screw head and the plunger sealing portion, wherein the meson is fixed on the outside of the guide portion, and the check ring is sleeved on the outside of the sealing portion.

6. The micro-precision plunger screw according to any one of claims 1 to 5, characterized in that: The plunger cylinder is hollow along the axial direction, and a glue passage is provided inside the plunger cylinder. The middle part of the glue passage is a plunger sealing channel. The inner wall of the front end of the glue passage is provided with a nozzle thread. The nozzle is fixed to the front end of the glue passage by the nozzle thread. The inner diameter of the tail end of the glue passage is the same as the inner diameter of the material pipe, and abuts against the front end of the material pipe.

7. The micro-precision plunger screw according to claim 1, characterized in that: The axial length of the plunger sealing channel is greater than the axial length of the plunger sealing portion.

8. The micro-precision plunger screw according to claim 1, characterized in that: The nozzle is through-through along its axial direction, and the inner diameter of the tail end of the nozzle is the same as the inner diameter of the plunger sealing channel.

9. The micro-precision plunger screw according to claim 1, characterized in that: The tail end of the screw is connected to a driving unit, and the driving unit is used to drive the screw as a whole to rotate and discharge materials along the material pipe and move back and forth to eject materials.

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