An ultra-high molecular weight polyethylene plasticizing extrusion device

Abstract

The present application relates to an ultra-high molecular weight polyethylene plasticizing extrusion device, which includes a barrel, a screw, a driving motor, a hopper and a die. The side wall of the barrel is provided with a plurality of side barrels connected to its inner cavity, the inner diameter of the side barrel is smaller than the inner diameter of the barrel, at least two side barrels are arranged on two opposite sides of the barrel, a piston is slidably provided in the side barrel, and a linear driving member for driving the piston to reciprocate is provided on the side barrel; a vibrating rod coaxial with the side barrel is provided through the center of the piston, a sealing member is provided between the vibrating rod and the piston, a vibrator is provided on the side barrel, one end of the vibrating rod is fixedly connected to the output end of the vibrator, and the free end of the vibrating rod extends into the barrel cavity and passes over the center of the barrel. The present application has the feature of high-frequency vibration of the barrel and the material in the side barrel by the reciprocating motion of the piston in the side barrel and the vibrating rod, thereby avoiding the problem that the material is difficult to heat and flow evenly during the extrusion process due to the high viscosity of the ultra-high molecular weight polyethylene melt, thereby affecting the quality and performance of the product.

Description

Technical Field

[0001] The present application relates to the technical field of polymer extrusion devices, and in particular to an ultra-high molecular weight polyethylene plasticizing extrusion device. Background Art

[0002] As the latest generation of high-performance resin, ultra-high molecular weight polyethylene (UHMWPE) has extremely high molecular weight (over 1.5 million), which enables UHMWPE products to have excellent properties that ordinary polyethylene materials do not have. Products made from UHMWPE resin have high mechanical strength, excellent wear resistance, light weight, environmental protection, and low water absorption, and are widely used in textiles, papermaking, food machinery, transportation, metallurgy, coal and other fields.

[0003] The Chinese patent with application number CN202311344508.9 in the related technology proposes a supercritical fluid-assisted polymer extrusion foaming device based on melt self-sealing, including a barrel, an extrusion screw, and an extrusion screw drive device; the extrusion screw includes a key connection section, a threaded sealing section, a compression section, a separation section and a transport section; the compression section and the transport section are provided with spiral screw ridges of opposite rotation directions, the compression section screw ridges and the inner wall of the barrel form a high-pressure melt cavity, and the bottom diameter of the compression section screw ridges gradually increases from front to back, and the transport section screw ridges and the inner wall of the barrel form a melt extrusion cavity; the barrel is provided with a first feed port and a discharge port connected to the high-pressure melt cavity, and a second feed port and a third feed port connected to the melt extrusion cavity are provided; a bypass valve that can adjust the pressure of the homogeneous solution in the high-pressure melt cavity is also connected between the discharge port and the third feed port. The invention effectively solves the difficult problems that supercritical fluid is easy to precipitate from the polymer melt and gas is easy to leak from the gap at the tail end of the extrusion screw during the extrusion process, and belongs to a polymer extrusion foaming device.

[0004] The above-mentioned related technologies have the following defects: the molecular weight of ultra-high molecular weight polyethylene is very high, so the material is easy to wrap around the screw and form a material plug, and its melt viscosity is extremely large and the fluidity is poor, which makes it difficult for the material to be heated and flowed evenly during the extrusion process, thereby affecting the quality and performance of the final extruded product, and also resulting in low production efficiency. Summary of the invention

[0005] In order to improve the problem that the material is difficult to heat and flow evenly during the extrusion process due to the high viscosity of the ultra-high molecular weight polyethylene melt, thereby affecting the quality and performance of the product, the present application provides an ultra-high molecular weight polyethylene plasticizing extrusion device.

[0006] The ultra-high molecular weight polyethylene plasticizing extrusion device provided in this application adopts the following technical solution:

[0007] An ultra-high molecular weight polyethylene plasticizing extrusion device comprises a barrel, a screw arranged in the barrel and a driving motor coaxially fixed to the rear end of the screw, the barrel is provided with a hopper and a die, the side wall of the barrel is provided with a plurality of side barrels connected with its inner cavity, the inner diameter of the side barrel is smaller than the inner diameter of the barrel, at least two of the side barrels are arranged at two opposite sides of the barrel, a piston is slidably arranged in the side barrel, and a linear driving member for driving the piston to reciprocate is provided on the side barrel;

[0008] A vibrating rod coaxial with the side tube is provided through the center of the piston, a seal is provided between the vibrating rod and the piston, a vibrator is provided on the side tube, one end of the vibrating rod is fixedly connected to the output end of the vibrator, and the free end of the vibrating rod extends into the barrel cavity and passes over the center of the barrel.

[0009] Furthermore, a closing portion is provided in the area of ​​the screw rod corresponding to the vibrating rod, the two vibrating rods arranged opposite to each other are arranged on two opposite sides of the closing portion, and the gap between the vibrating rod and the screw rod is larger than the amplitude of the vibrating rod.

[0010] Furthermore, the free end of the vibration rod is fixedly connected to a vibration spring coaxial therewith.

[0011] Furthermore, the angle between the side barrel and the barrel where the drive motor is provided is an acute angle.

[0012] Furthermore, the two opposite side barrels are staggered along the length direction of the barrel.

[0013] Furthermore, the movement directions of the two pistons in the two barrels arranged opposite to each other are opposite.

[0014] Furthermore, a heating cover is provided on the outer wall of the side tube.

[0015] Furthermore, the surfaces of the vibration rod and the vibration spring are provided with a smooth coating.

[0016] Furthermore, a reciprocating sleeve is coaxially fixedly connected to the end of the piston away from the barrel, one end of the reciprocating sleeve away from the barrel is connected to the output end of the linear drive component, and the reciprocating sleeve is sleeved outside the vibrating rod and is provided with a gap therebetween.

[0017] In summary, the beneficial technical effects of this application are:

[0018] 1. When the material moves toward the die in the barrel under the action of the screw, the pistons in the side barrels on the two opposite sides of the barrel reciprocate in the side barrels under the action of the linear drive member, and the material is continuously drawn in and out of the side barrels, which can increase the fluidity of the material, help the material to be transported and distributed in the extrusion barrel, and reduce the stagnation of the material in the barrel; and the vibrating rod vibrates the material in the barrel and the side barrel at a high frequency under the action of the vibrator, so that the material in the barrel is subjected to a strong shear force during the extrusion process, which further accelerates the flow of the material in the barrel and improves the melting efficiency. At the same time, the material can be better mixed, thereby improving the uniformity and consistency of the product, and effectively solving the problem that the high viscosity of the ultra-high molecular weight polyethylene melt makes it difficult to evenly heat and flow the material during the extrusion process, thereby affecting the quality and performance of the product;

[0019] 2. When the vibrator drives the vibrating rod to vibrate at high frequency, the piston sleeve is arranged on the outer periphery of the vibrating rod to make reciprocating motion, which can change the inherent set amplitude of the vibrating rod, so that the vibration of the vibrating rod on the molten material in the barrel tends to be disordered vibration, which can further improve the mixing uniformity of the molten material; and when the piston moves in the direction away from the barrel, the amplitude of the vibrating rod is large and can vibrate fully; when the piston moves in the direction close to the barrel, the amplitude of the vibrating rod is suppressed and reduced, which can effectively avoid the occurrence of phenomena such as degradation of molten material caused by excessive vibration;

[0020] 3. By setting a vibration spring, the original rigid rotation can be made flexible with the help of the elastic potential energy of the vibration spring itself, further reducing the probability of degradation of ultra-high molecular weight polyethylene due to excessive vibration; at the same time, the contact area between the vibration spring and the molten material is increased, and the receiving surface for transmitting the oscillation wave is increased, which can also avoid excessive concentration of the oscillation wave on a certain point of the molten material; and the above-mentioned pitch setting of the vibration spring ensures that the highly viscous ultra-high molecular weight polyethylene molten material can effectively pass through the gap of the vibration spring itself, thereby ensuring the vibration effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present application;

[0022] Figure 2 is a side view of the overall structure of an embodiment of the present application;

[0023] Figure 3 is along Figure 2 Schematic diagram of the cross-sectional structure along the AA line;

[0024] Figure 4 It is a schematic diagram of a partial cross-sectional structure of an embodiment of the present application.

[0025] Explanation of the reference numerals: 1. barrel; 11. hopper; 12. die; 2. screw; 21. closing part; 3. driving motor; 4. side barrel; 41. heating cover; 5. piston; 51. sealing element; 52. reciprocating sleeve; 6. linear driving element; 7. vibrating rod; 71. vibrating spring; 8. vibrator. DETAILED DESCRIPTION

[0026] The technical solution of the present application will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0027] The present application embodiment discloses an ultra-high molecular weight polyethylene plasticizing extrusion device. Figure 1 , Figure 2 , Figure 3 and Figure 4 A device for plasticizing and extruding ultra-high molecular weight polyethylene comprises a barrel 1, a screw 2 disposed in the barrel 1, and a driving motor 3 coaxially fixed to the rear end of the screw 2. The barrel 1 is provided with a hopper 11 and a die 12. The side wall of the barrel 1 is provided with a plurality of side barrels 4 connected to its inner cavity, the inner diameter of the side barrel 4 is smaller than the inner diameter of the barrel 1, and at least two side barrels 4 are arranged at two opposite sides of the barrel 1; specifically, in the embodiment of the present application, two side barrels 4 are provided, and the two side barrels 4 are arranged at two opposite sides of the barrel 1.

[0028] In addition, a piston 5 is slidably arranged in the side tube 4, and a linear driving member 6 for driving the piston 5 to reciprocate is arranged on the side tube 4. The linear driving member 6 can be a linear motor, a cylinder or a hydraulic cylinder; and a vibrating rod 7 coaxial with the side tube 4 is arranged through the center of the piston 5, and a sealing member 51 is arranged between the vibrating rod 7 and the piston 5. The sealing member 51 is specifically made of high-temperature resistant rubber. A vibrator 8 is arranged on the side tube 4, and one end of the vibrating rod 7 is fixedly connected to the output end of the vibrator 8, and the free end of the vibrating rod 7 extends into the cavity of the barrel 1 and passes through the center of the barrel 1.

[0029] After such arrangement, when the ultra-high molecular weight polyethylene is plasticized and extruded, the drive motor 3 is started first and the barrel 1 is heated, the raw material is added to the barrel 1 through the hopper 11, the material is heated and melted in the barrel 1, and then moves toward the die 12 under the action of the screw 2, and finally extruded from the die 12. At the same time, the pistons 5 in the side tubes 4 on the two opposite sides of the separate barrel 1 reciprocate in the side tubes 4 under the action of the linear drive member 6, and the molten material is continuously drawn into and pushed out of the side tubes 4, which can increase the fluidity of the molten material, help to convey and distribute the molten material in the extrusion barrel 1, reduce the stagnation of the molten material in the barrel 1, and improve the heating uniformity of the molten material; and, the vibrating rod 7, under the action of the vibrator 8, vibrates the molten material in the barrel 1 and the side tube 4 at high frequency, so that the molten material in the barrel 1 is subjected to a strong shear force during the extrusion process, which can further accelerate the flow of the molten material in the barrel 1 and improve the melting efficiency. At the same time, the molten material can be better mixed, thereby improving the uniformity and consistency of the product, and effectively solving the problem that the ultra-high molecular weight polyethylene melt has a high viscosity, which makes it difficult to evenly heat and flow the material during the extrusion process, thereby affecting the quality and performance of the extruded product.

[0030] Moreover, when the vibrator 8 drives the vibrating rod 7 to vibrate at high frequency, the piston 5 is sleeved on the outer periphery of the vibrating rod 7 and reciprocates, which can change the inherent set amplitude of the vibrating rod 7, so that the vibration of the vibrating rod 7 on the molten material in the barrel 1 tends to be disordered vibration, which can further improve the mixing uniformity of the molten material, and can effectively promote the material in the dead zone to re-enter the main flow path, reduce the residence time of the molten material at high temperature, and ensure product quality.

[0031] Specifically, during the movement of the piston 5, when the piston 5 moves in a direction away from the barrel 1, part of the molten material in the barrel 1 enters the side barrel 4. At this time, the piston 5 is located at the end of the vibrating rod 7 close to the vibrator 8, and the amplitude of the vibrating rod 7 tends to be close to the set value, that is, tends to be a larger amplitude. At this time, the vibrating rod 7 can not only fully vibrate the large amount of molten material in the barrel 1 with a high amplitude, but also vibrate the molten material in the side barrel 4 with a lower amplitude, which can ensure the consistency of the vibration effect on the overall molten material as much as possible. When the piston 5 moves in a direction close to the barrel 1, the molten material in the side barrel 4 is pushed into the barrel 1. At this time, the piston 5 is located at the end of the vibrating rod 7 away from the vibrating gas, and the amplitude of the vibrating rod 7 is suppressed and reduced, that is, at this time, the amplitude of the vibrating rod 7 to the part of the molten material re-entering the barrel 1 from the side barrel 4 and the molten material in this area of ​​the barrel 1 is reduced, which can effectively avoid the occurrence of phenomena such as degradation of molten materials caused by excessive vibration, and can greatly ensure the extrusion quality of ultra-high molecular weight polyethylene products.

[0032] More specifically, see Figure 3 and Figure 4, the screw 2 is provided with a closing portion 21 in the area corresponding to the vibrating rod 7, and the closing portion 21 is correspondingly provided in a columnar shape coaxial with the main axis of the screw 2, and no spiral propulsion blades are provided in the closing portion 21; the two vibrating rods 7 arranged opposite to each other are arranged on two opposite sides of the closing portion 21, for example, one vibrating rod 7 is located above the closing portion 21, and the other vibrating rod 7 is located below the closing portion 21, and the gap between the vibrating rod 7 and the screw 2 is greater than the amplitude of the vibrating rod 7. In this way, by providing the closing portion 21 on the screw 2, the head end of the vibrating rod 7 can effectively cross the rotating screw 2 and stay in the middle area of ​​the barrel 1 for a long time, so that the molten material in the barrel 1 can be vibrated more fully and evenly.

[0033] And in order to further promote the vibration effect of the vibrating rod 7 on the viscous molten material, refer to Figure 3 and Figure 4 A coaxial vibration spring 71 is fixedly connected to the free end of the vibration rod 7. The outer diameter of the vibration spring 71 is larger than that of the vibration rod 7. The vibration spring 71 is made of a spring with a high stiffness coefficient. In the specific setting, the pitch of the vibration spring 71 is not less than half of its inner diameter. In this way, when the vibration rod 7 is driven by the vibrator 8 to vibrate at a high frequency, it can also follow the vibration, and with the elastic potential energy of the vibration spring 71 itself, the original rigid rotation can be made flexible, further reducing the probability of ultra-high molecular weight polyethylene being degraded by excessive vibration; at the same time, the contact area between the vibration spring 71 and the molten material is increased, and the receiving surface for transmitting the oscillation wave is increased, which can also prevent the oscillation wave from being excessively concentrated in a certain place of the molten material; and the above-mentioned pitch setting of the vibration spring 71 ensures that the highly viscous ultra-high molecular weight polyethylene molten material can effectively pass through the gap of the vibration spring 71 itself, ensuring the vibration effect.

[0034] And refer to Figure 1 , Figure 3 and Figure 4 The angle between the side barrel 4 and the end of the barrel 1 where the driving motor 3 is provided is an acute angle. When the material in the barrel 1 is sucked into the side barrel 4, the part of the molten material flows in the opposite direction to the flow direction of the molten material in the barrel 1, which can greatly promote the flow of the overall molten material in the barrel 1; and when the material in the side barrel 4 is transported to the barrel 1, it can play a pushing effect on the material in the barrel 1, which can further reduce the stagnation of the material in the barrel 1, improve the fluidity of the material, and also reduce the residence time of the molten material in the closing part 21 area on the screw 2, which may cause excessive vibration degradation.

[0035] Furthermore, refer to Figure 1 and Figure 4 The two opposite side tubes 4 are staggered along the length direction of the barrel 1. The staggered side tubes 4 can promote the mixing of the materials in the barrel 1, so that the materials are continuously stirred and mixed during the forward process, thereby improving the uniformity of the materials and improving the plasticizing efficiency.

[0036] And refer to Figure 1 and Figure 4 The movement directions of the two pistons 5 in the two relatively arranged barrels 1 are opposite, which can produce staggered flow and stirring effects, thereby achieving more effective mixing when the material passes through the side barrel 4 and improving the uniformity of the material; at the same time, it can also promote the flow of the material in the barrel 1, reduce the stagnation and dead zone of the material in the barrel 1, and improve the fluidity of the material.

[0037] And, refer to Figure 4 A heating hood 41 is provided on the outer wall of the side barrel 4, which can additionally heat the molten material in the side barrel 4, promote better melting and plasticization of the material in the middle area of ​​the barrel 1, thereby improving the plasticization efficiency of the entire extrusion system.

[0038] At the same time, the surface of the vibration rod 7 and the vibration spring 71 is provided with a smooth coating (not shown in the figure), and the smooth coating can specifically be a nickel-plated layer, which can reduce the adhesion of materials on the surface of the vibration rod 7 and the vibration spring 71 and improve the fluidity of the materials; at the same time, it can also extend the service life of the vibration rod 7 and the vibration spring 71.

[0039] In addition, refer to Figure 4 The end of the piston 5 away from the barrel 1 is coaxially fixed with a reciprocating sleeve 52, and the end of the reciprocating sleeve 52 away from the barrel 1 is connected to the output end of the linear drive member 6, and the reciprocating sleeve 52 is sleeved outside the vibrating rod 7 and is provided with a gap therebetween. This not only plays a role in motion conversion, but also improves the stability and reliability of the system, and at the same time can reduce the direct impact of the piston 5 on the linear drive member 6, thereby extending the service life of the linear drive member 6.

[0040] The implementation principle of an ultra-high molecular weight polyethylene plasticizing extrusion device in the embodiment of the present application is:

[0041] When plasticizing and extruding ultra-high molecular weight polyethylene, the drive motor 3 is first started and the barrel 1 is heated. The raw material is added to the barrel 1 through the hopper 11. After the material is heated and melted in the barrel 1, it moves toward the die 12 under the action of the screw 2 and is finally extruded from the die 12. At the same time, the pistons 5 in the side tubes 4 on the two opposite sides of the separate barrel 1 reciprocate in the side tubes 4 under the action of the linear drive member 6, and the molten material is continuously drawn into and pushed out of the side tubes 4, which can increase the fluidity of the molten material, help to convey and distribute the molten material in the extrusion barrel 1, reduce the stagnation of the molten material in the barrel 1, and improve the heating uniformity of the molten material; and, the vibrating rod 7, under the action of the vibrator 8, vibrates the molten material in the barrel 1 and the side tube 4 at high frequency, so that the molten material in the barrel 1 is subjected to a strong shear force during the extrusion process, which can further accelerate the flow of the molten material in the barrel 1 and improve the melting efficiency. At the same time, the molten material can be better mixed, thereby improving the uniformity and consistency of the product, and effectively solving the problem that the ultra-high molecular weight polyethylene melt has a high viscosity, which makes it difficult to evenly heat and flow the material during the extrusion process, thereby affecting the quality and performance of the extruded product.

[0042] Moreover, when the vibrator 8 drives the vibrating rod 7 to vibrate at high frequency, the piston 5 is sleeved on the outer periphery of the vibrating rod 7 and reciprocates, which can change the inherent set amplitude of the vibrating rod 7, so that the vibration of the vibrating rod 7 on the molten material in the barrel 1 tends to be disordered vibration, which can further improve the mixing uniformity of the molten material, and can effectively promote the material in the dead zone to re-enter the main flow path, reduce the residence time of the molten material at high temperature, and ensure product quality.

[0043] Specifically, during the movement of the piston 5, when the piston 5 moves in a direction away from the barrel 1, part of the molten material in the barrel 1 enters the side barrel 4. At this time, the piston 5 is located at the end of the vibrating rod 7 close to the vibrator 8, and the amplitude of the vibrating rod 7 tends to be close to the set value, that is, tends to be a larger amplitude. At this time, the vibrating rod 7 can not only fully vibrate the large amount of molten material in the barrel 1 with a high amplitude, but also vibrate the molten material in the side barrel 4 with a lower amplitude, which can ensure the consistency of the vibration effect on the overall molten material as much as possible. When the piston 5 moves in a direction close to the barrel 1, the molten material in the side barrel 4 is pushed into the barrel 1. At this time, the piston 5 is located at the end of the vibrating rod 7 away from the vibrating gas, and the amplitude of the vibrating rod 7 is suppressed and reduced, that is, at this time, the amplitude of the vibrating rod 7 to the part of the molten material re-entering the barrel 1 from the side barrel 4 and the molten material in this area of ​​the barrel 1 is reduced, which can effectively avoid the occurrence of phenomena such as degradation of molten materials caused by excessive vibration, and can greatly ensure the extrusion quality of ultra-high molecular weight polyethylene products.

[0044] Unless otherwise defined, the technical terms or scientific terms used in this application should be understood by people with ordinary skills in the field to which this application belongs. The words "first", "second", "third" and similar words used in the specification and claims of this application do not indicate any order, quantity or importance, but are only used to distinguish different components. "One" or "one" and similar words do not indicate a quantitative limit, but indicate that there is at least one. "Include" or "comprise" and similar words mean that the elements or objects appearing before "include" or "comprise" include the elements or objects listed after "include" or "comprise" and their equivalents, and do not exclude other elements or objects. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0045] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. An ultra-high molecular weight polyethylene plasticizing extrusion device, comprising a barrel (1), a screw (2) arranged in the barrel (1), and a drive motor (3) coaxially fixed to the rear end of the screw (2), wherein the barrel (1) is provided with a hopper (11) and a die (12), characterized in that: The side wall of the barrel (1) is provided with a plurality of side barrels (4) in communication with the inner cavity thereof, the inner diameter of the side barrel (4) being smaller than the inner diameter of the barrel (1), at least two of the side barrels (4) being arranged on two opposite sides of the barrel (1), a piston (5) being slidably arranged in the side barrel (4), and a linear driving member (6) for driving the piston (5) to reciprocate is arranged on the side barrel (4); A vibrating rod (7) coaxial with the side tube (4) is provided through the center of the piston (5), a sealing member (51) is provided between the vibrating rod (7) and the piston (5), a vibrator (8) is provided on the side tube (4), one end of the vibrating rod (7) is fixedly connected to the output end of the vibrator (8), and the free end of the vibrating rod (7) extends into the cavity of the barrel (1) and passes over the center of the barrel (1); The screw rod (2) is provided with a closing portion (21) in a region corresponding to the vibrating rod (7), the two vibrating rods (7) arranged opposite to each other are arranged on two opposite sides of the closing portion (21), and the gap between the vibrating rod (7) and the screw rod (2) is greater than the vibration amplitude of the vibrating rod (7); The free end of the vibration rod (7) is fixedly connected to a vibration spring (71) coaxial therewith.

2. The ultra-high molecular weight polyethylene plasticizing extrusion device according to claim 1, characterized in that: The angle between the side barrel (4) and the end of the barrel (1) where the drive motor (3) is provided is an acute angle.

3. The ultra-high molecular weight polyethylene plasticizing extrusion device according to claim 1, characterized in that: The two opposite side barrels (4) are arranged in a staggered manner along the length direction of the barrel (1).

4. The ultra-high molecular weight polyethylene plasticizing extrusion device according to claim 3, characterized in that: The movement directions of the two pistons (5) in the two barrels (1) arranged opposite to each other are opposite.

5. The ultra-high molecular weight polyethylene plasticizing extrusion device according to claim 1, characterized in that: The outer wall of the side tube (4) is provided with a heating cover (41).

6. The ultra-high molecular weight polyethylene plasticizing extrusion device according to claim 1, characterized in that: The surfaces of the vibration rod (7) and the vibration spring (71) are provided with a smooth coating.

7. The ultra-high molecular weight polyethylene plasticizing extrusion device according to claim 1, characterized in that: A reciprocating sleeve (52) is coaxially fixedly connected to the end of the piston (5) away from the barrel (1); one end of the reciprocating sleeve (52) away from the barrel (1) is connected to the output end of the linear drive member (6); and the reciprocating sleeve (52) is sleeved outside the vibrating rod (7) and is provided with a gap therebetween.

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