High-precision injection mold

Abstract

The invention discloses a high-precision injection mold and relates to the technical field of injection molds, the high-precision injection mold comprises a movable mold, a fixed mold and an exhaust assembly, the exhaust assembly comprises an air outlet through groove, a sliding barrel and a conical plug, and the air outlet through groove is vertically formed in the top of the movable mold in a penetrating mode and communicates with a forming cavity; the sliding barrel is elastically and slidably arranged at the lower end of the interior of the air outlet through groove, an annular plate is arranged on the outer side wall of the sliding barrel, a switch part is arranged between the moving groove and the annular plate in a matched mode, a conical groove is formed in the bottom end of the air outlet through groove, and the conical plug is arranged at the end, close to the conical groove, of the sliding barrel and used for being matched with the conical groove. A plurality of through holes are formed in the side face of the end, close to the conical plug, of the sliding barrel in a penetrating mode. By arranging the exhaust assembly, the situation that in the injection molding process, due to the fact that a large amount of air is reserved in the cavity, the injection molding pressure cannot enable flowing glue to flow to an end point all the time, and the size accuracy of a product cannot be guaranteed is prevented.

Description

Technical Field

[0001] The invention relates to the technical field of injection molds, and in particular to a high-precision injection mold. Background Art

[0002] Injection molding technology is also known as injection molding. It is an injection and molding processing method. At a certain temperature, completely molten plastic material is injected into the mold cavity by high pressure. After cooling and solidification, a molded product is obtained. This method is suitable for mass production of parts with complex shapes. It has the advantages of fast production speed, high efficiency and automation. After the model is cooled and solidified, it is taken out of the mold cavity.

[0003] An injection mold is disclosed in the authorization announcement number CN114889061A. The present invention provides an injection mold, including an upper mold, a lower mold, a glue injection head and a sealing mechanism. A glue injection port is arranged at the top of the upper mold. The glue injection head is arranged in cooperation with the glue injection port so that the glue injection head can be connected to the glue injection port. The sealing mechanism is arranged in cooperation with the glue injection port so that the sealing mechanism can open or close the glue injection port. The sealing mechanism is provided with a sealing plug. When the sealing mechanism seals the glue injection port, the sealing plug is flush with the inner wall of the mold cavity of the upper mold. After the glue injection head injects molten glue into the mold cavity through the glue injection port, the sealing mechanism makes the sealing plug seal the glue injection port. When the glue is cooled, the upper mold and the lower mold are opened to take out the injection molded part. After the glue is injected into the injection mold, it is compacted by the sealing plug, so that no redundant part is formed, thereby reducing waste.

[0004] However, when using injection molding to produce plastic parts, there is often air in the molding cavity of the injection mold. During injection molding, the glue flows into the mold cavity, and the air at the end of the cavity cannot be discharged, which becomes "dead air" or "trapped air". When the glue continues to flow in, the air is compressed under the action of pressure. No matter how much pressure is added, the trapped air cannot be compressed to zero. In other words, no matter how much injection pressure the injection molding machine increases, the glue can never flow to the end point, and the dimensional accuracy of the product cannot be guaranteed. Summary of the invention

[0005] The purpose of the present invention is to provide a high-precision injection mold to solve the technical problem in the prior art that the air in the mold cavity cannot be discharged.

[0006] The technical problem to be solved by the present invention can be achieved by the following technical solutions:

[0007] A high-precision injection mold, comprising a movable mold and a fixed mold, wherein the movable mold is movably arranged above the fixed mold, the movable mold and the fixed mold are closed to form a molding cavity, the top of the molding cavity is connected to an injection molding component, and further comprising:

[0008] An exhaust component, the exhaust component includes an air outlet groove, a slide cylinder and a conical plug, the air outlet groove is vertically penetrated and arranged on the top of the movable mold and is connected with the molding cavity, the slide cylinder is elastically slidably arranged at the lower end of the air outlet groove, an annular plate is arranged on the outer side wall of the slide cylinder, and movable grooves communicating with the air outlet groove are also opened on both sides of the air outlet groove, a switch member is matched between the movable groove and the annular plate, a conical groove is opened at the bottom end of the air outlet groove, the conical plug is arranged at one end of the slide cylinder close to the conical groove, and the conical plug is a truncated cone structure for matching the conical groove, and a plurality of through holes are opened on the side surface of one end of the slide cylinder close to the conical plug;

[0009] The mold locking assembly is engaged and clamped at the connection between the movable mold and the fixed mold to enhance the connection strength between the movable mold and the fixed mold. The mold locking assembly is controlled to open and close by a switch.

[0010] As a further solution of the present invention: a return spring is sleeved on the outer side of the slide cylinder, one end of the return spring is connected to the top wall of the moving groove, and the other end is connected to the annular plate.

[0011] As a further solution of the present invention: the switch element includes a power-carrying block 1 and a thermal bimetal strip, the power-carrying block 1 is arranged on the top of the annular plate, and a power-carrying block 2 vertically aligned with the power-carrying block 1 is arranged on the side wall of the movable groove, and one end of the power-carrying block 2 away from the power-carrying block 1 is connected to the end of the thermal bimetal strip through a connecting wire, and the other end of the thermal bimetal strip is connected to the power-carrying connection end, and the end of the power-carrying connection end cooperates with the locking assembly.

[0012] As a further solution of the present invention: both sides of the fixed mold are provided with protrusions, and the end of the movable mold close to the fixed mold is also provided with a clamping block that matches the protrusions, and the protrusions are clamped with the clamping block.

[0013] As a further solution of the present invention: the locking assembly includes an electromagnetic block and a magnet, a transverse groove is provided on the clamping block, an electromagnetic block is arranged at one end of the transverse groove away from the protrusion, the electromagnetic block is electrically connected to the energized connection end, a clamping slot is also provided on the clamping block and is transversely connected to the transverse groove, the end of the clamping slot also extends to the protrusion, a magnet is slidably connected inside the transverse groove, the electromagnetic block cooperates with the magnet, a clamping column is connected to one end of the magnet away from the electromagnetic block, the clamping column is slidably connected inside the clamping slot, and a retaining spring is also arranged between the magnet and the end of the transverse groove.

[0014] As a further solution of the present invention: an automatic demolding structure is also provided on the fixed mold, and the automatic demolding structure includes a top block and a bending plate. An operating groove is opened inside the fixed mold, and a plurality of support springs are distributed on the bottom plate of the operating groove. The tops of the support springs are connected to the bending plates, and pressure rods are provided on both sides of the bending plates. The pressure rods are inserted through the top of the fixed mold, and the top ends are matched with the bottom of the movable mold. A groove is also provided at the connection between the top of the fixed mold and the molding cavity, and a top block is clamped inside the groove, and a linkage rod is connected to the bottom of the top block, and the linkage rod is vertically slidably connected to the fixed mold, and the end portion is fixedly connected to the top of the bending plate.

[0015] As a further solution of the present invention: the top block is in a truncated cone shape.

[0016] As a further solution of the present invention: a filter assembly is arranged on the top of the air outlet slot, and the filter assembly includes a mounting block, and the mounting block is detachably mounted on the top of the air outlet slot, a hollow groove is arranged inside the mounting block, the air outlet slot is connected to the hollow groove, and a third filter element, a second filter element, and a first filter element are arranged in sequence from top to bottom inside the hollow groove of the mounting block.

[0017] Beneficial effects of the present invention:

[0018] 1. The present invention sets an exhaust component to prevent a large amount of air from remaining in the cavity during the injection molding process, resulting in the injection pressure never being able to make the glue flow to the endpoint, and the dimensional accuracy of the product cannot be guaranteed. At the same time, a filter component is set up, and three layers of filtering materials are set to prevent harmful substances from spreading to the surrounding environment through the air outlet groove.

[0019] 2. The present invention sets a locking mold assembly between the movable mold and the fixed mold. When the conical groove and the conical plug are closed during injection molding, the locking film assembly automatically starts to engage the movable mold with the fixed mold, thereby enhancing the stability of the connection between the movable mold and the fixed mold and preventing the movable mold and the fixed mold from expanding and separating due to excessive air pressure inside the molding cavity. After the injection molding is completed, the locking film assembly is automatically released, and the degree of automation is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be further described below in conjunction with the accompanying drawings.

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

[0022] Figure 2 It is a top view of the overall structure of the present invention;

[0023] Figure 3 For the present invention Figure 2 Sectional view in the AA direction;

[0024] Figure 4 For the present invention Figure 3 The enlarged structural diagram at A in the middle;

[0025] Figure 5 For the present invention Figure 3 The enlarged structural diagram at B in the middle;

[0026] Figure 6 For the present invention Figure 3 Enlarged structural diagram at point C in the middle.

[0027] In the figure: 1. movable mold; 2. fixed mold; 3. convex block; 4. clamping block; 5. molding cavity; 6. top block; 7. groove; 8. linkage rod; 9. bending plate; 10. pressure rod; 11. support spring; 12. air outlet groove; 13. cone groove; 14. slide cylinder; 15. cone plug; 16. through hole; 17. movable groove; 18. annular plate; 19. reset spring; 20. power block one; 21. power block two; 22. thermal bimetallic strip; 23. power connection end; 24. mounting block; 25. third filter element; 26. second filter element; 27. first filter element; 28. transverse groove; 29. ​​clamping slot; 30. electromagnetic block; 31. magnet; 32. clamping column; 33. holding spring. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] like Figure 1-Figure 6 As shown, a high-precision injection mold comprises a movable mold 1 and a fixed mold 2. The movable mold 1 is movably arranged above the fixed mold 2. A lifting assembly is arranged above the movable mold 1 to drive the movable mold 1 to approach or move away from the fixed mold 2. The movable mold 1 and the fixed mold 2 are closed to form a molding cavity 5. An injection port is opened through the top of the molding cavity 5. The injection assembly is connected to the injection port to inject flowing raw materials into the molding cavity 5. The injection mold also includes an exhaust assembly and a clamping assembly.

[0030] The exhaust assembly includes an exhaust slot 12, a slide cylinder 14 and a conical plug 15. Figure 3As shown, the air outlet groove 12 is vertically arranged on the top of the movable mold 1 and is connected to the molding cavity 5. The slide 14 is elastically slidably arranged at the lower end of the air outlet groove 12. The outer wall of the slide 14 is provided with an annular plate 18. Both sides of the air outlet groove 12 are also provided with movable grooves 17 connected thereto. A switch member is provided between the movable groove 17 and the annular plate 18. A conical groove 13 is provided at the bottom of the air outlet groove 12. A conical plug 15 is fixedly arranged at one end of the slide 14 close to the conical groove 13, and the conical plug 15 is a truncated cone structure for matching the conical groove 13. A plurality of through holes 16 are provided on the side surface of one end of the slide 14 close to the conical plug 15 for air circulation, wherein the slide 14 and the conical plug 15 are integrated, and the slide 14 is slidably arranged in the air outlet groove 12 to control the on-off of the molding cavity 5 and the outside air.

[0031] The clamping assembly is fitted and clamped at the connection between the movable mold 1 and the fixed mold 2 to enhance the connection strength between the movable mold 1 and the fixed mold 2. The clamping assembly is opened and closed by a switch.

[0032] In some specific embodiments, such as Figure 3 or Figure 4 As shown, in order to facilitate the automatic reset of the slide 14, a reset spring 19 is sleeved on the outer side of the slide 14, one end of the reset spring 19 is fixedly connected to the top wall of the movable groove 17, and the other end is fixedly connected to the annular plate 18. In the initial state, the reset spring 19 will press the annular plate 18, so that an air channel is left between the conical groove 13 and the conical plug 15, and the gas can flow at this time. As the gas is discharged, the injection molding material will push the conical plug 15, thereby compressing the reset spring 19. At this time, the conical groove 13 and the conical plug 15 are in contact with each other to prevent the injection molding material from flowing out.

[0033] In some specific embodiments, such as Figure 4 As shown, in order to facilitate the movement of the slide 14 to automatically start the film locking assembly, the switch element includes a power block 20 and a thermal bimetal 22. The power block 20 is fixedly arranged on the top of the annular plate 18, and the power block 20 is connected to the power end. A power block 21 vertically aligned with the power block 20 is fixedly arranged on the side wall of the movable groove 17. The end of the power block 21 away from the power block 20 is electrically connected to the end of the thermal bimetal 22 through a connecting line, and the other end of the thermal bimetal 22 is electrically connected to the power connection end 23. The end of the power connection end 23 cooperates with the mold locking assembly. Whether the power block 20 and the power block 21 are in contact determines the opening and closing of the film locking assembly.

[0034] In some specific embodiments, such as Figure 1As shown, in order to facilitate the alignment of the movable mold 1 and the fixed mold 2, protrusions 3 are fixedly provided on both sides of the fixed mold 2, and a clamping block 4 matching with the protrusion 3 is also fixedly provided on the end of the movable mold 1 close to the fixed mold 2, and the protrusion 3 is clamped with the clamping block 4.

[0035] In some specific embodiments, such as Figure 3 or Figure 6 As shown, in order to prevent the movable mold 1 and the fixed mold 2 from expanding and separating due to excessive air pressure inside the molding cavity 5 when the plastic is injected, the clamping assembly includes an electromagnetic block 30 and a magnet 31. A transverse groove 28 is provided on the clamping block 4. The electromagnetic block 30 is fixedly provided at one end of the transverse groove 28 away from the protrusion 3. The electromagnetic block 30 is electrically connected to the power connection end 23. A clamping groove 29 is also provided on the clamping block 4 and is transversely connected to the transverse groove 28. The end of the clamping groove 29 also extends to the protrusion 3. A magnet 31 is slidably connected inside the transverse groove 28. The electromagnetic block 30 cooperates with the magnet 31 to electrically connect the magnet 31 to the protrusion 3. When the magnetic block 30 is energized, the contact surfaces with the magnet 31 repel each other with the same poles, which can push the magnet 31 to move away from the electromagnetic block 30. The end of the magnet 31 away from the electromagnetic block 30 is fixedly connected to a clamping column 32, and the clamping column 32 is slidably connected inside the clamping groove 29. Whether the electromagnetic block 30 is energized determines whether the movable mold 1 and the fixed mold 2 are engaged. A supporting spring 33 is also provided between the magnet 31 and the end of the transverse groove 28. One end of the supporting spring 33 is fixedly connected to the inner wall of the transverse groove 28, and the other end is fixedly connected to the magnet 31 for resetting the magnet 31.

[0036] In some specific embodiments, such as Figure 3 As shown, in order to facilitate automatic demoulding after injection molding, an automatic demoulding structure is also provided on the fixed mold 2, and the automatic demoulding structure includes a top block 6 and a bending plate 9. An operating groove is provided inside the fixed mold 2, and a plurality of support springs 11 are distributed and fixedly provided on the bottom plate of the operating groove. The tops of the support springs 11 are fixedly connected to the bending plates 9. Pressure rods 10 are fixedly provided on both sides of the bending plates 9. The pressure rods 10 are inserted through the top of the fixed mold 2, and the top ends are matched with the bottom of the movable mold 1. When the movable mold 1 moves downward, the pressure rods 10 can be pressed to move downward. A groove 7 is also provided at the connection between the top of the fixed mold 2 and the molding cavity 5, and a top block 6 is clamped inside the groove 7. A linkage rod 8 is fixedly connected to the bottom of the top block 6, and the linkage rod 8 is vertically slidably connected to the fixed mold 2, and the ends are fixedly connected to the top of the bending plate 9.

[0037] In some specific embodiments, such as Figure 3 As shown, in order to enhance the sealing between the top block 6 and the groove 7, the top block 6 is in a truncated cone shape to prevent the raw material from leaking.

[0038] In some specific embodiments, such as Figure 3 or Figure 5As shown, in order to facilitate filtering of the exhausted gas, a filter assembly is arranged on the top of the air outlet slot 12, and the filter assembly includes a mounting block 24, and the mounting block 24 is detachably mounted on the top of the air outlet slot 12 by screws or buckles for easy replacement. A hollow groove is arranged inside the mounting block 24, and the air outlet slot 12 is connected to the hollow groove. A third filter element 25, a second filter element 26, and a first filter element 27 are fixedly arranged inside the hollow groove of the mounting block 24 from top to bottom. Fiber filtration is adopted in the first filter element 27, activated carbon filtration is adopted in the second filter element 26, and a filter screen is adopted in the third filter element 25, so that harmful substances in the air to be exhausted can be filtered without affecting the exhaust.

[0039] In order to facilitate the understanding of the embodiments of this solution by those skilled in the art, the working principle of this solution is briefly described in combination with specific application scenarios:

[0040] When in use, the movable mold 1 and the fixed mold 2 are closed. Under the pressure of the movable mold 1, the pressure rod 10 moves downward, and the bending plate 9 presses the support spring 11 downward to compress the support spring 11. At the same time, under the connection of the linkage rod 8, the top block 6 moves downward into the ejection groove 7 until the upper end surface of the top block 6 is flush with the top of the groove 7. At this time, the molding cavity 5 is formed, and the raw material is heated and melted into a flowing state, and flows into the molding cavity 5 from the injection port. With the continuous inflow of the raw material, the air in the molding cavity 5 flows upward. In the initial state, the return spring 19 will tighten the annular plate 18, so that an air flow port is left between the conical plug 15 and the conical groove 13. At this time, the gas flows from between the conical plug 15 and the conical groove 13, and then flows out through the through hole 16 to the top of the air outlet groove 12;

[0041] When the injection material reaches the top of the molding cavity 5, the injection material will push the conical plug 15, thereby compressing the reset spring 19. At this time, the conical plug 15 fits with the conical groove 13, and the air flow port is closed to prevent the injection material from flowing out. When the reset spring 19 is compressed, the annular plate 18 drives the power block 1 20 to approach the power block 2 21. When the conical groove 13 fits with the conical plug 15, the power block 21 contacts the power block 1 20, and the current supplying power to the power block 1 20 is from the power block 21 to the power block 21. The block 21 transmits the current to the hot bimetallic strip 22, and the current passes through the hot bimetallic strip 22 and the power connection end 23 to energize the electromagnetic block 30 to generate magnetic force. After the electromagnetic block 30 is energized, the contact surface with the magnet 31 repels each other with the same poles. The electromagnetic block 30 pushes the magnet 31 to drive the clamping column 32 to move. At this time, the supporting spring 33 is compressed, and the clamping column 32 runs through the entire clamping groove 29, so that the movable mold 1 and the fixed mold 2 are engaged, so as to avoid the movable mold 1 and the fixed mold 2 from expanding and separating due to excessive air pressure when the raw material is passed;

[0042] During the last stage of injection molding and the process of injection molding completion, the current is still continuously transmitted to the thermal bimetallic strip 22, so that the temperature of the thermal bimetallic strip 22 continues to increase. Due to the characteristic that the thermal bimetallic strip 22 will bend and deform when it is energized and heated, when the temperature reaches a certain level, the current path is disconnected, and then the electromagnetic block 30 no longer forms a magnetic field and repels the magnet 31. Due to the resilience of the holding spring 33, the magnet 31 drives the clamping column 32 to move toward one end close to the electromagnetic block 30 and restore to the unclamped state, that is, when the injection molding reaches the conical groove 13 and the conical plug When 15 is closed, the film locking assembly automatically starts to engage the movable mold 1 with the fixed mold 2. After the injection molding is completed, the film locking assembly is automatically released, and the degree of automation is high. After a period of time, the raw material is cooled and formed, and the movable mold 1 and the fixed mold 2 are separated. Under the tension of the support spring 11, the bending plate 9 drives the linkage rod 8 to move upward, so that the ejector block 6 ejects the plastic part, and then the plastic part is taken down. The automatic demoulding saves time and effort, and the finished product is taken out. The reset spring 19 will drive the conical plug 15 away from the conical groove 13 to reopen the air flow channel, which is convenient for the next injection molding.

[0043] Several embodiments of the present invention are described in detail above, but the embodiments of the present invention are not limited thereto and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A high-precision injection mold, comprising a movable mold (1) and a fixed mold (2), wherein the movable mold (1) is movably arranged above the fixed mold (2), the movable mold (1) and the fixed mold (2) are closed to form a molding cavity (5), and the top of the molding cavity (5) is connected to an injection molding component, characterized in that: Also includes: An exhaust component, the exhaust component comprises an exhaust groove (12), a slide cylinder (14) and a conical plug (15), the exhaust groove (12) is vertically arranged on the top of the movable mold (1) and is connected to the molding cavity (5), the slide cylinder (14) is elastically slidably arranged at the lower end of the exhaust groove (12), the outer wall of the slide cylinder (14) is provided with an annular plate (18), and the two sides of the exhaust groove (12) are also provided with movable grooves (18) connected thereto. 7), a switch member is provided between the movable groove (17) and the annular plate (18), a conical groove (13) is provided at the bottom end of the air outlet groove (12), the conical plug (15) is provided at one end of the slide cylinder (14) close to the conical groove (13), and the conical plug (15) is in a truncated cone structure for matching the conical groove (13), and a plurality of through holes (16) are provided on the side surface of one end of the slide cylinder (14) close to the conical plug (15); A mold locking assembly is engaged and clamped at the connection between the movable mold (1) and the fixed mold (2) to enhance the connection strength between the movable mold (1) and the fixed mold (2). The opening and closing of the mold locking assembly is controlled by a switch.

2. A high-precision injection mold according to claim 1, characterized in that: A return spring (19) is sleeved on the outer side of the slide cylinder (14), one end of the return spring (19) is connected to the top wall of the moving groove (17), and the other end is connected to the annular plate (18).

3. A high-precision injection mold according to claim 1, characterized in that: The switch element comprises a power-on block (20) and a thermal bimetallic strip (22); the power-on block (20) is arranged on the top of the annular plate (18); a power-on block (21) vertically aligned with the power-on block (20) is arranged on the side wall of the movable groove (17); one end of the power-on block (21) away from the power-on block (20) is connected to the end of the thermal bimetallic strip (22) through a connecting wire; the other end of the thermal bimetallic strip (22) is connected to a power-on connection end (23); the end of the power-on connection end (23) cooperates with a clamping assembly.

4. A high-precision injection mold according to claim 1, characterized in that: Both sides of the fixed mold (2) are provided with protrusions (3), and the end of the movable mold (1) close to the fixed mold (2) is also provided with a clamping block (4) that matches the protrusion (3), and the protrusion (3) is clamped with the clamping block (4).

5. A high-precision injection mold according to claim 4, characterized in that: The clamping assembly comprises an electromagnetic block (30) and a magnet (31). The clamping block (4) is provided with a transverse groove (28). The end of the transverse groove (28) away from the protrusion (3) is provided with the electromagnetic block (30). The electromagnetic block (30) is electrically connected to the power connection end (23). The clamping block (4) is also provided with a groove (29) which is transversely connected to the transverse groove (28). The end of the groove (29) also extends to the protrusion (3). The interior of the transverse groove (28) is slidably connected with a magnet (31). The electromagnetic block (30) cooperates with the magnet (31). The end of the magnet (31) away from the electromagnetic block (30) is connected with a clamping column (32). The clamping column (32) is slidably connected inside the groove (29). A retaining spring (33) is also provided between the magnet (31) and the end of the transverse groove (28).

6. A high-precision injection mold according to claim 1, characterized in that: The fixed mold (2) is also provided with an automatic demoulding structure, which includes a top block (6) and a bending plate (9). An operating groove is provided inside the fixed mold (2), and a plurality of support springs (11) are distributed on the bottom plate of the operating groove. The tops of the support springs (11) are connected to the bending plates (9). Pressure rods (10) are provided on both sides of the bending plates (9). The pressure rods (10) are inserted through the top of the fixed mold (2), and the top ends are matched with the bottom of the movable mold (1). A groove (7) is also provided at the connection between the top of the fixed mold (2) and the molding cavity (5). A top block (6) is provided in the groove (7), and a linkage rod (8) is connected to the bottom of the top block (6). The linkage rod (8) is vertically slidably connected to the fixed mold (2), and the ends are fixedly connected to the top of the bending plate (9).

7. A high-precision injection mold according to claim 6, characterized in that: The top block (6) is in the shape of a truncated cone.

8. A high-precision injection mold according to claim 1, characterized in that: The top of the air outlet groove (12) is provided with a filter assembly, the filter assembly comprising a mounting block (24), the mounting block (24) being detachably mounted on the top of the air outlet groove (12), a hollow groove being provided inside the mounting block (24), the air outlet groove (12) being communicated with the hollow groove, and a third filter element (25), a second filter element (26), and a first filter element (27) being provided inside the hollow groove of the mounting block (24) in order from top to bottom.

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