A Rotating Shaft Type Axial Vibration Excitation Device and an Injection Molding Machine

Abstract

The present invention discloses a rotating shaft type axial vibration excitation device and an injection molding machine. The rotating shaft type axial vibration excitation device includes a connecting sleeve, an outer sleeve, a rotating connecting piece, and a power driver. When the outer sleeve and the connecting sleeve rotate relative to each other and the outer sleeve moves axially, the injection screw and the connecting sleeve vibrate slightly axially synchronously, which can improve the solid compaction ability, thereby improving the heat conduction efficiency (i.e., the melting rate), reducing the melt viscosity. When the material is dynamically injected, due to the reduction of the melt viscosity, the fluidity is enhanced, the flow resistance can be effectively reduced, and thus the internal stress generated by the rapid cooling and solidification of the material in the mold cavity can be reduced, and the uneven filling of the material in the mold cavity can be improved; when the material is under pressure, the material in the mold cavity shrinks due to cooling, and the dynamic vibration can enhance the melt compensation ability in the mold cavity, which can improve the molding accuracy of the product and the surface quality.

Description

Technical Field

[0001] The present invention belongs to the field of injection molding machines, and particularly relates to a rotating shaft type axial vibration excitation device, and also relates to an injection molding machine for realizing dynamic injection, plasticization and pressure holding. Background Art

[0002] An injection molding machine, also known as an injection molding machine or an injection machine. It is the main molding equipment for making various shaped plastic products from thermoplastic or thermosetting plastics using plastic molding dies. The injection molding machine can heat the plastic, apply high pressure to the molten plastic, and inject it to fill the mold cavity.

[0003] Specifically, the injection motion state mainly includes the following actions:

[0004] 1). Injection: The injection motor drives the rotating screw rod to push the injection molding screw forward;

[0005] 2). Pressure holding: Keep the pressure in the mold cavity and the material pipe unchanged for a period of time, and at this time the injection motor continues to do work;

[0006] 3). Feeding: The feeding motor drives the injection molding screw to rotate (the injection molding screw can only rotate in one direction);

[0007] 4). Rear relaxation: When the feeding motor drives the injection molding screw to rotate, the pressure at the front section of the injection molding screw will become larger and larger to generate back pressure. At this time, the ball screw needs to move backward to release the back pressure, and at this time the feeding motor and the injection motor work simultaneously.

[0008] At the same time, the dynamic injection molding technology: During the injection molding process, an axial pulsating oscillation force is generated on the injection molding screw, that is, an axial vibration is generated on the injection molding screw during the pressure holding and feeding stages to improve the product yield and feeding efficiency.

[0009] Currently, for high-precision injection molding, precision hydraulic injection molding machines or all-electric injection molding machines are generally used, which are expensive and still improved on the basis of steady-state injection molding.

[0010] The processing and molding principle of traditional hydraulic injection molding machines is steady-state injection molding. The rotation shear of the injection molding screw is used to realize the change of the material from a solid state to a molten state, and finally the product injection molding is realized through injection and pressure holding.

[0011] During the steady-state injection molding process, the material is completely conveyed by friction, and the heat energy source for the plasticization and melting state of the material all comes from the heat generated by friction and the energy of the external heating coil. Therefore, there is often an uneven plasticization phenomenon in steady-state injection molding.

[0012] In addition, due to the high viscosity of the molten plastic, the resistance during the plasticization process is large. Moreover, during the steady-state injection and holding pressure stages, due to the crystallization effect of the material and the shrinkage effect during the product forming process, the local stress state distribution in the product is uneven, which may cause product quality defects such as warping, cracking, weld lines, etc. Summary of the Invention

[0013] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide an improved shaft-type axial vibration device.

[0014] Meanwhile, the present invention also relates to an injection molding machine for realizing dynamic injection, plasticization, and holding pressure.

[0015] To solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0016] A shaft-type axial vibration device includes a connecting sleeve, an outer sleeve, a rotating connecting member, and a power driver. The connecting sleeve is coaxial with and fixedly connected to the injection molding screw. The outer sleeve is sleeved on the outer periphery of the connecting sleeve. The rotating connecting member connects the connecting sleeve and the outer sleeve, and the connecting sleeve and the outer sleeve are relatively movably arranged axially and circumferentially. The power driver is arranged on the outer sleeve and drives the outer sleeve to reciprocally swing axially relative to the connecting sleeve. When the outer sleeve reciprocally swings, the rotating connecting member transmits the acting force to the connecting sleeve, and the connecting sleeve and the injection molding screw vibrate reciprocally along the axis direction.

[0017] Preferably, the reciprocating vibration displacement of the connecting sleeve and the injection molding screw along the axis direction is -0.2 mm to 0.2 mm.

[0018] Specifically, the reciprocating vibration displacement of the connecting sleeve and the injection molding screw along the axis direction is -0.1 mm to 0.1 mm, so as to achieve micro-movement within this displacement range. In this way, during the plasticization process: the axial micro-amplitude vibration brought by the shaft-type axial vibration device can improve the solid compaction ability, thereby improving the heat conduction efficiency (i.e., the melting rate); reducing the melt viscosity; during the injection process: due to the reduction of the melt viscosity and the enhanced fluidity, the flow resistance can be effectively reduced, thereby reducing the internal stress generated by the rapid cooling and solidification of the material in the mold cavity and improving the uneven filling phenomenon of the mold cavity; during the holding pressure stage: the material in the mold cavity shrinks due to cooling, and the dynamic vibration can enhance the melt compensation ability in the mold cavity, which can improve the molding accuracy of the product and the surface quality.

[0019] Preferably, the reciprocating vibration frequency of the connecting sleeve and the injection molding screw along the axis direction is 5 to 20 HZ. The optimal vibration frequency is 15 HZ.

[0020] According to a specific implementation and preferred aspect of the present invention, the rotating connecting member is a ball guide sleeve, and the ball guide sleeve includes a sleeve body fixed on the connecting sleeve, and a plurality of balls distributed circumferentially around the sleeve body, wherein the plurality of balls are in contact with the inner wall of the outer sleeve. The connection of the balls can reduce friction, thereby facilitating the implementation of axial micro-vibration when the injection screw rotates.

[0021] According to a specific implementation and preferred aspect of the present invention, the outer periphery of the connecting sleeve is provided with an annular groove that is recessed inward from the surface, and the power driver includes a power motor disposed on the outer sleeve at the position corresponding to the annular groove, and an eccentric wheel that is transmission-connected to the output shaft of the power motor and whose center is offset from the center of the output shaft, wherein the eccentric wheel is located in the annular groove, and when the output shaft rotates, the eccentric wheel and the inner wall of the annular groove are in contact, pushing the power motor and the outer sleeve to swing back and forth along the axis direction. In other words, when the power motor rotates, the rotor of the power motor drives the eccentric wheel to rotate, and the eccentrically placed structure enables the outer sleeve to swing back and forth axially when the power motor rotates, and at the same time, due to the interaction of forces, the connecting sleeve will also vibrate back and forth axially.

[0022] Preferably, a bearing is formed on the outer periphery of the eccentric wheel, and the eccentric wheel is connected to the output shaft through the eccentric wheel shaft. In this way, the bearing rolling on the outer periphery of the eccentric wheel contacts the inner wall of the annular groove, further reducing friction, facilitating the motion control of the eccentric wheel, and reducing power loss.

[0023] According to another specific implementation and preferred aspect of the present invention, the power driver further includes a spacing disc whose axis coincides with the axis of the output shaft and is fixed to the end of the output shaft, and the eccentric wheel shaft is arranged on the spacing disc so as to be movable and adjustable along the circumference of the spacing disc from the end away from the eccentric wheel. In this way, the center distance between the eccentric wheel shaft and the output shaft is adjustable, and thus the displacement range of the amplitude can be changed, that is, the smaller the center distance between the eccentric wheel shaft and the output shaft, the larger the displacement range of the amplitude; conversely, the larger the center distance between the eccentric wheel shaft and the output shaft, the smaller the displacement range of the amplitude, thereby meeting the working needs under different states.

[0024] Preferably, an annular avoidance groove is formed on the inner wall of the outer sleeve and is opposite to the annular groove, the distance adjustment disc is located in the annular avoidance groove, and the power motor is located at the lower part of the outer sleeve. In this way, there is enough space to install the components of the power driver, and at the same time, under the further counterweight of the power motor, the outer sleeve and the connecting sleeve rotate relative to each other, that is, the connecting sleeve rotates relative to the outer sleeve.

[0025] Further, a chute extending along the circumferential direction is formed in the adjusting disc, and the eccentric wheel shaft is slidably disposed in the chute through a connection module provided at an end away from the eccentric wheel. The power driver further includes an adjusting threaded rod provided on the distance adjusting disc for driving the connection module to slide in the chute. Herein, under the rotation of the adjusting threaded rod, the connection module approaches or moves away from the center of the distance adjusting disc. Here, the adjusting threaded rod can drive the displacement of the connection module by tightening or loosening; or the adjusting threaded rod is a lead screw, which forms a lead screw-nut structure with the connection module. Under the rotation of the lead screw, the nut moves linearly, thereby driving the connection module to move linearly in the chute.

[0026] Preferably, the displacement of the outer sleeve reciprocally swinging along the axial center line direction is -100 mm to 100 mm; the frequency of the outer sleeve reciprocally swinging along the axial center line direction is 5 to 20 HZ.

[0027] Another technical solution of the present invention is: an injection molding machine for realizing dynamic injection, plasticization and pressure holding, which includes:

[0028] A barrel, which includes a barrel body and a nozzle, wherein a plastic raw material inlet is provided on the barrel body;

[0029] An injection screw, which extends along the length direction of the barrel;

[0030] An injection power device, which is used to drive the injection screw to rotate around its own axis and move linearly along its own length direction;

[0031] A rotating shaft type axial vibration exciting device, which is located between the barrel and the injection power device.

[0032] Due to the implementation of the above technical solutions, the present invention has the following advantages compared with the prior art:

[0033] When the relative rotation between the outer sleeve and the connecting sleeve and the axial movement of the outer sleeve cause the injection screw and the connecting sleeve to synchronously perform micro-amplitude vibrations in the axial direction, the present invention can improve the solid compaction ability, thereby improving the heat conduction efficiency (i.e., the melting rate), and also reducing the melt viscosity. When the material is in dynamic injection, due to the reduction of the melt viscosity and the enhancement of the fluidity, the flow resistance can be effectively reduced, thereby reducing the internal stress generated by the rapid cooling and solidification of the material in the mold cavity and improving the uneven filling phenomenon of the mold cavity; when the material is under pressure holding, the material in the mold cavity shrinks due to cooling, and the dynamic vibration can enhance the melt compensation ability in the mold cavity, which can improve the molding accuracy of the product and the surface quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a schematic structural diagram of the injection molding machine of the present invention;

[0035] Figure 2 is Figure 1Schematic enlarged view of the structure of the central rotating shaft type axial excitation device;

[0036] Figure 3 is Figure 2 left view schematic diagram of;

[0037] Figure 4 is Figure 2 top view schematic diagram of;

[0038] Wherein: 1. Barrel; 10. Cylinder body; 11. Nozzle;

[0039] 2. Injection screw;

[0040] 3. Injection power device;

[0041] 4. Central rotating shaft type axial excitation device; 40. Connecting sleeve; 400. Annular groove; 41. Outer sleeve; 410. Annular avoidance groove; 42. Rotating connecting piece; 420. Sleeve body; 421. Ball; 43. Power driver; 430. Power motor; s. Output shaft; 431. Distance adjusting disc; h. Slide groove; 432. Eccentric wheel shaft; 433. Eccentric wheel; 434. Bearing; 435. Connecting module; 436. Distance adjusting threaded rod. Specific embodiments

[0042] In order to make the above objects, features and advantages of the present application more obvious and understandable, the following will describe the specific embodiments of the present application in detail with reference to the accompanying drawings. Many specific details are set forth in the following description in order to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0043] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present application.

[0044] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of this application, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0045] In this application, unless otherwise clearly defined and limited, terms such as "installed", "connected", "joined", "fixed", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0046] In this application, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature can be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature can be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0047] It should be noted that when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or there can also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation.

[0048] As Figure 1 shown, the injection molding machine for realizing dynamic injection, plasticization and holding pressure in this embodiment includes a barrel 1, an injection screw 2, an injection power device 3, and a rotary shaft type axial vibration excitation device 4 located between the barrel 1 and the injection power device 3.

[0049] The barrel 1 includes a barrel body 10 having a cavity inside and a nozzle 11 located at the left end of the barrel body 10, and a plastic raw material inlet is provided on the barrel body 10.

[0050] The injection molding screw 2 extends along the length direction of the barrel 10, and its left end is located inside the barrel 10, where the axis line of the injection molding screw 2 coincides with the center line of the barrel 10.

[0051] The injection molding power device 3 is used to drive the injection molding screw to rotate around its own axis and move linearly along its own length direction.

[0052] The rotating shaft type axial vibration exciter 4 is located between the right end of the barrel 10 and the left end of the injection molding power device 3.

[0053] Combined Figure 2 As shown, the rotating shaft type axial vibration exciter 4 includes a connecting sleeve 40 coaxially and fixedly connected with the injection molding screw 2, an outer sleeve 41, a rotating connecting member 42 located between the outer sleeve 41 and the connecting sleeve 40 to enable relative rotation and relative linear movement of the outer sleeve 41 and the connecting sleeve 40 around their own axis lines, and a power driver 43 for driving the outer sleeve 41 to swing reciprocally along the axial direction.

[0054] The axis lines of the outer sleeve 41, the injection molding screw 2, and the connecting sleeve 40 coincide with each other.

[0055] In this example, when the outer sleeve 41 swings reciprocally along its own axis line, the rotating connecting member 42 transmits the acting force to the connecting sleeve 40, and the connecting sleeve 40 and the injection molding screw 2 vibrate reciprocally along the axis line direction.

[0056] Specifically, the rotating connecting member 42 is a ball bushing, and the ball bushing includes a bushing body 420 and multiple balls 421 circumferentially distributed around the bushing body 420, where the balls 421 are located between the outer wall of the connecting sleeve 40 and the inner wall of the outer sleeve 41. With the connection of the balls here, the friction force can be reduced, which is convenient for implementing axial micro-amplitude vibration under the condition of the rotation of the injection molding screw.

[0057] In this example, the outer sleeve 41 is relatively heavy. Therefore, the rotation between the outer sleeve 41 and the connecting sleeve 40 means that the connecting sleeve 40 rotates relative to the stationary outer sleeve 41, and for the axial reciprocating movement, under the interaction of forces, the connecting sleeve 40 will also receive an axial force and thus generate axial vibration.

[0058] Combined Figure 3 and Figure 4As shown in the figure, an annular groove 400 recessed inward from the surface is provided on the outer periphery of the connecting sleeve 40, and an annular avoidance groove 410 recessed inward from the wall surface is formed on the inner wall of the outer sleeve 41. The power driver 43 includes a power motor 430 provided at the lower part of the outer sleeve 41 corresponding to the annular avoidance groove 410, an adjustment distance disc 431 fixed to the upper end of the output shaft s of the power motor 430 and having the axis line coinciding with the axis line of the output shaft s, an eccentric wheel shaft 432 movably arranged along the circumferential direction of the adjustment distance disc 431 on the adjustment distance disc 431, an eccentric wheel 433 provided at the top of the eccentric wheel shaft 432, and a bearing 434 (which can be a ball bearing or a needle bearing) provided on the outer periphery of the eccentric wheel 433. The adjustment distance disc 431 is located in the annular avoidance groove 410, and the eccentric wheel 433 and the bearing 434 are located in the annular groove 400 and the outer peripheral part of the bearing 434 abuts against the side wall of the annular groove 400. When the output shaft rotates, under the abutment of the bearing 434 and the inner wall of the annular groove 400, the power motor 430 and the outer sleeve 41 are pushed to reciprocally swing along the axis line direction. That is to say, when the power motor 430 rotates, the rotor of the power motor 430 drives the eccentric wheel 433 and the bearing 434 to rotate, and drives the power motor 430 and the outer sleeve 41 to perform axial reciprocating swing. At the same time, due to the interaction of forces, the connecting sleeve 40 will simultaneously perform axial reciprocating vibration.

[0059] As can be seen from the above, the central distance between the eccentric wheel shaft 432 and the output shaft s is adjustable, and thus the displacement range of the amplitude can be changed. That is to say, the smaller the central distance between the eccentric wheel shaft 432 and the output shaft s, the larger the displacement range of the amplitude; conversely, the larger the central distance between the eccentric wheel shaft 432 and the output shaft s, the smaller the displacement range of the amplitude. Therefore, it meets the working requirements in different states.

[0060] In this example, the power motor 430 is located at the lower part of the outer sleeve 41, and the power motor 430 is a three-phase six-pole asynchronous motor. Here, since the mass of the outer sleeve is relatively heavy, and with the counterweight of the power motor, when the eccentric wheel rotates, it will not cause the outer sleeve to rotate around its own axis line, but can only perform linear reciprocating swing along the length direction of the axis line.

[0061] At the same time, in order to implement the adjustable central distance between the eccentric wheel shaft 432 and the output shaft s, in this example, a chute h extending along the circumferential direction is provided on the adjustment disc 431. The lower end of the eccentric wheel shaft 432 is fixedly provided with a connection module 435 matching the chute h, and the connection module 435 can move along the extension direction of the chute h in the chute h. The power driver 43 further includes an adjustment threaded rod 436 provided on the adjustment distance disc 431 for driving the connection module 435 to slide in the chute. When the adjustment threaded rod 436 rotates, the connection module 435 is set to approach or move away from the center of the adjustment distance disc 431.

[0062] Specifically, the distance-adjusting threaded rod 436 can drive the displacement of the connection module 435 by tightening or loosening; or the distance-adjusting threaded rod is a lead screw, which forms a lead screw-nut structure with the connection module. Under the rotation of the lead screw, the nut moves linearly, thereby driving the connection module to move linearly in the chute.

[0063] At the same time, in this example, the reciprocating swing displacement of the outer sleeve 41 along the axial center line direction is -40 mm to 40 mm; the reciprocating swing frequency of the outer sleeve along the axial center line direction is 15 HZ. In this way, the reciprocating vibration displacement of the injection screw along the axial center line direction is -0.1 mm to 0.1 mm; the reciprocating vibration frequency of the injection screw along the axial center line direction is 15 HZ.

[0064] In summary, the implementation process of this embodiment is as follows:

[0065] In the working state of injection molding (regardless of any state of the injection screw, such as rotation or linear motion), the rotor of the three-phase six-pole asynchronous motor drives the eccentric wheel with bearings outside to rotate. Under the rolling contact between the bearing and the side wall of the annular groove, when the three-phase six-pole asynchronous motor rotates, the outer sleeve makes an axial reciprocating swing. In this way, under the interaction of forces, the connecting sleeve will also make an axial reciprocating vibration at the same time, so as to realize the reciprocating motion of the injection screw during plasticization, injection, and pressure holding, and achieve the dynamic injection effect. Moreover, the injection screw only needs to achieve a vibration state with a vibration displacement of -0.1 mm to 0.1 mm and a vibration frequency of about 15 HZ to significantly improve the plasticization efficiency and injection molding quality.

[0066] Therefore, the advantages of this embodiment are as follows: During the plasticization and transportation process of the material, the position of the shaft-type axial vibration exciter and the axial micro-amplitude vibration of the injection screw can not only reduce the plasticization and transportation distance, but also improve the solid compaction ability, thereby improving the heat conduction efficiency (i.e., the melting rate), and also reducing the melt viscosity, etc.; during the dynamic injection of the material, due to the reduction of the melt viscosity and the enhancement of the fluidity, the flow resistance can be effectively reduced, thereby reducing the internal stress generated by the rapid cooling and solidification of the material in the mold cavity and improving the uneven filling phenomenon of the mold cavity; during the pressure holding of the material, the material in the mold cavity shrinks due to cooling, and the dynamic vibration can enhance the melt compensation ability in the mold cavity, which can improve the molding accuracy of the product and improve the surface quality. During the plasticization process: the axial micro-amplitude vibration brought by the shaft-type axial vibration exciter can improve the solid compaction ability, thereby improving the heat conduction efficiency (i.e., the melting rate); reducing the melt viscosity, etc.; during the injection process: due to the reduction of the melt viscosity and the enhancement of the fluidity, the flow resistance can be effectively reduced, thereby reducing the internal stress generated by the rapid cooling and solidification of the material in the mold cavity and improving the uneven filling phenomenon of the mold cavity; during the pressure holding stage: the material in the mold cavity shrinks due to cooling, and the dynamic vibration can enhance the melt compensation ability in the mold cavity, which can improve the molding accuracy of the product and improve the surface quality.

[0067] The above has described the present invention in detail, aiming to enable those skilled in this field to understand the content of the present invention and implement it. However, it should not be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A shaft - type axial vibration excitation device, characterized in that, the shaft - type axial vibration excitation device includes a connecting sleeve, an outer sleeve, a rotating connecting piece and a power driver. The connecting sleeve is coaxial with and fixedly connected to an injection screw. The outer sleeve is sleeved on the outer periphery of the connecting sleeve. The rotating connecting piece connects the connecting sleeve and the outer sleeve, and the connecting sleeve and the outer sleeve are relatively movably arranged axially and circumferentially. An annular groove recessed inward from the surface is provided on the outer periphery of the connecting sleeve. The central axes of the outer sleeve, the injection screw and the connecting sleeve coincide. The power driver is arranged on the outer sleeve and drives the outer sleeve to reciprocally swing axially relative to the connecting sleeve. The power driver includes a power motor arranged on the outer sleeve corresponding to the annular groove, and an eccentric wheel that is in transmission connection with the output shaft of the power motor and whose center deviates from the center of the output shaft. The eccentric wheel is located in the annular groove. When the output shaft rotates, under the contact of the eccentric wheel with the inner wall of the annular groove, the power motor and the outer sleeve are pushed to reciprocally swing along the central axis direction. When the outer sleeve reciprocally swings, the rotating connecting piece transmits the acting force to the connecting sleeve, and the connecting sleeve and the injection screw reciprocally vibrate along the central axis direction.

2. The shaft - type axial vibration excitation device according to claim 1, characterized in that, the reciprocating vibration displacement of the connecting sleeve and the injection screw along the central axis direction is - 0.2 mm to 0.2 mm.

3. The shaft - type axial vibration excitation device according to claim 1, characterized in that, the reciprocating vibration frequency of the connecting sleeve and the injection screw along the central axis direction is 5 - 20 HZ.

4. The shaft - type axial vibration excitation device according to claim 1, characterized in that, the rotating connecting piece is a ball guide sleeve, and the ball guide sleeve includes a sleeve body and multiple balls circumferentially distributed around the sleeve body. The balls are located between the outer wall of the connecting sleeve and the inner wall of the outer sleeve.

5. The shaft - type axial vibration excitation device according to claim 1, characterized in that, a bearing or a roller is further provided on the outer periphery of the eccentric wheel.

6. The shaft - type axial vibration excitation device according to claim 5, characterized in that, the power driver further includes an adjusting distance disc whose central axis coincides with the central axis of the output shaft and is fixed to the end of the output shaft. The eccentric wheel is connected to the adjusting distance disc through an eccentric wheel shaft, and the eccentric wheel shaft is arranged on the adjusting distance disc to be movable and adjustable along the circumferential direction of the adjusting distance disc.

7. The shaft - type axial vibration excitation device according to claim 6, characterized in that, an annular avoidance groove opposite to the annular groove is formed on the inner wall of the outer sleeve. The adjusting distance disc is located in the annular avoidance groove, and the power motor is located at the lower part of the outer sleeve.

8. The shaft - type axial vibration excitation device according to claim 6 or 7, characterized in that, A chute extending circumferentially is formed in the adjusting disc. The eccentric wheel shaft is slidably disposed in the chute through a connection module provided at an end of the eccentric wheel away from the eccentric wheel. The power driver further includes an adjusting threaded rod disposed on the distance adjusting disc for driving the connection module to slide in the chute. Under the rotation of the adjusting threaded rod, the eccentric wheel approaches or moves away from the center of the distance adjusting disc.

9. The shaft-type axial excitation device according to claim 1, characterized in that the displacement of the outer sleeve swinging reciprocally along the axial center line direction is -100 mm to 100 mm.

10. The shaft-type axial excitation device according to claim 1, characterized in that the frequency of the outer sleeve swinging reciprocally along the axial center line direction is 5 to 20 HZ.

11. An injection molding machine for realizing dynamic injection, plasticization and pressure holding, which comprises: a barrel, which includes a barrel body and a nozzle, wherein a plastic raw material inlet is provided on the barrel body; an injection screw, which extends along the length direction of the barrel; an injection power device, which is used for driving the injection screw to rotate around its own axis and move linearly along its own length direction. The injection molding machine is characterized in that the injection molding machine further includes a shaft-type axial excitation device as described in any one of claims 1 to 10 and located between the barrel and the injection power device.

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