Novel riser capable of improving exhaust effect

Abstract

The utility model relates to the technical field of casting, in particular to a novel riser capable of improving exhaust effect, which comprises an upper riser and a lower riser, the bottom of the upper riser and the top of the lower riser are integrally formed, a first cavity is formed in the upper riser, a second cavity is formed in the lower riser, the top of the upper riser is open, and the top of the lower riser is open. A heat preservation riser sleeve is arranged at the top of the upper riser, the middle structure of the heat preservation riser sleeve abuts against the corresponding position of the top of the upper riser, the lower end of the heat preservation riser sleeve extends into the first cavity, and a material receiving structure is arranged in the middle of the heat preservation riser sleeve. A plurality of exhaust structures are arranged around the vertical center line of the insulated riser sleeve at intervals at the peripheral position of the insulated riser sleeve, the bottom of the lower riser is open, and an opening in the bottom of the lower riser is used for being communicated with an external cavity through a built-in pouring gate. The utility model has the following beneficial effects: the exhaust effect is improved; molten metal in the dead head is prevented from being solidified earlier than molten metal in the cavity, and the quality of a casting is guaranteed.

Description

Technical Field

[0001] The utility model relates to the technical field of casting, in particular to a novel riser which can improve the exhaust effect. Background Art

[0002] The riser is a supplementary part added to the top or side of the casting to avoid defects in the casting. Its main function is to compensate for the liquid shrinkage of the liquid metal in the mold cavity and the solid shrinkage of the casting during solidification, thereby avoiding casting defects such as shrinkage cavities, shrinkage, cracks and deformation in the metal casting.

[0003] For example, in the patent document with patent publication number CN220329911U, a heat-generating and heat-insulating riser is disclosed, which includes a riser body, a plurality of exhaust holes are arranged at the upper end of the riser body, a partition is arranged between any two adjacent exhaust holes, the partition is located in the mold cavity of the riser body, the partition is used to divide the mold cavity into a plurality of separate chambers, each chamber corresponds to the exhaust hole, and one end of the partition is arranged on the riser body.

[0004] According to the existing technical literature, the riser has a heating baffle added in the middle of its inner cavity, which increases the calorific value of the riser. However, the disadvantage of the riser is that the heating baffle used to heat the aluminum liquid is a prefabricated part, which is often made by a certain amount of thermite, co-solvent, oxidant and thermal insulation material. Therefore, the heat released by its reaction is also a certain amount. When the volume of the casting is large, more molten metal is needed for shrinkage compensation, and the time required is also long. Therefore, as the exothermic reaction rate of the heating baffle gradually decreases, its calorific value also gradually decreases. Therefore, the temperature of the molten metal in the riser will gradually decrease, causing its fluidity to deteriorate or even solidify. When it is completely solidified, the solidification process of the casting may not be over yet, and it cannot play the role of shrinkage compensation at this time, and the casting is prone to quality defects.

[0005] To this end, the utility model optimizes and improves the problem in the prior art that the heat generated by the riser is certain but it is difficult to continue to provide effective heating over time. Hereby, a new riser structure is proposed which can achieve long-term heating by flexibly adding heating to the inside of the riser, so as to better solve the problems in the prior art. Utility Model Content

[0006] The utility model is to solve one of the above technical problems, and the technical solution adopted is: a new type of riser that can improve the exhaust effect, including an upper riser and a lower riser, the bottom of the upper riser and the top of the lower riser are integrally formed, a first cavity is formed inside the upper riser, and a second cavity is formed inside the lower riser, the top of the upper riser is open, a thermal insulation riser sleeve is provided on the top of the upper riser, the middle structure of the thermal insulation riser sleeve is pressed against the corresponding position of the top of the upper riser along the horizontal circumferential direction, the lower end of the thermal insulation riser sleeve extends into the interior of the first cavity, a material connection structure is provided at the middle position of the thermal insulation riser sleeve, and a plurality of exhaust structures are provided at intervals around the vertical center line of the thermal insulation riser sleeve at the outer position of the thermal insulation riser sleeve, the bottom of the lower riser is open, and the bottom opening of the lower riser is used to communicate with the external cavity through a built-in runner.

[0007] In any of the above schemes, it is preferred that the thermal insulation riser sleeve includes a supporting cover plate, first hooks are fixedly installed on the left and right sides of the top surface of the supporting cover plate respectively, a columnar abutment block is integrally formed in the middle of the bottom surface of the supporting cover plate, and a truncated cone plug-in block is integrally formed at the bottom of the columnar abutment block, the material connection structure passes through the supporting cover plate, the columnar abutment block and the truncated cone plug-in block in sequence in the vertical direction, the lower part of the material connection structure is fixedly arranged on the bottom surface of the truncated cone plug-in block, the exhaust structure passes through the supporting cover plate, the columnar abutment block and the truncated cone plug-in block in sequence in the vertical direction, and the upper part of the exhaust structure is fixedly arranged on the top surface of the supporting cover plate;

[0008] When the thermal insulation riser sleeve is in working condition, the columnar abutment block and the truncated cone-shaped plug-in block jointly pass downward through the top opening of the upper riser, the lower part of the material connection structure extends into the first cavity, the bottom of the outer periphery of the support cover plate presses against the corresponding position of the top of the upper riser, and the circumferential side wall of the columnar abutment block abuts against the vertical inner wall of the top opening of the upper riser.

[0009] In any of the above schemes, preferably, the material connection structure includes a placement seat, the top of the placement seat and the middle of the bottom surface of the truncated cone shaped plug-in block are integrally formed, the placement seat and the bottom surface of the truncated cone shaped plug-in block form a placement cavity for placing the heating block, and a filling channel is opened from top to bottom at the corresponding positions of the support cover plate, the columnar abutment block and the truncated cone shaped plug-in block, the lower end of the filling channel is connected with the interior of the placement cavity, and the upper end of the filling channel is connected with the external environment, and also includes a thermal insulation sealing block, the lower part of the thermal insulation sealing block is inserted into the inner cavity of the upper end of the filling channel, the bottom of the upper step section of the thermal insulation sealing block cooperates and abuts at the corresponding position of the top surface of the support cover plate, and a second hook is fixedly installed on the top of the thermal insulation sealing block.

[0010] In any of the above schemes, preferably, the exhaust structure includes a vertically arranged conical exhaust needle, a first exhaust channel is formed inside the conical exhaust needle, the bottom of the conical exhaust needle is fixedly mounted on one side of the top of the support cover plate, and a second exhaust channel is opened from top to bottom at corresponding positions of the support cover plate, the columnar abutment block and the truncated cone-shaped plug-in block, the lower end of the first exhaust channel is connected to the upper end of the second exhaust channel and the two are internally connected, and the lower end of the second exhaust channel is connected to the interior of the first cavity.

[0011] In any of the above schemes, preferably, the second cavity is in a truncated cone shape, and the diameter of the upper opening of the second cavity is larger than the diameter of the lower opening thereof.

[0012] Compared with the prior art, the beneficial effects of the utility model are as follows:

[0013] 1. The utility model can greatly improve the exhaust efficiency by setting up multiple sets of exhaust structures. At the same time, through the tapered structure of the tapered exhaust needle, the upper end of the tapered exhaust needle can achieve a jet effect to a certain extent, preventing external debris from entering the molten metal in the riser.

[0014] 2. The utility model arranges a plurality of conical exhaust needles on the top of the insulating riser sleeve. When the molding sand completely covers the top surface of the cover plate, the conical exhaust needles can pass through the molding sand so that the first cavity continues to be connected with the external atmosphere. This not only ensures that the gas in the first cavity can be discharged smoothly through the second exhaust channel and the conical exhaust needles, but also ensures that the external atmospheric pressure can continue to act on the metal liquid surface in the first cavity to ensure the shrinkage compensation pressure.

[0015] 3. The utility model provides a placement seat at the bottom of the insulation riser sleeve. The operator can add a heating block to the placement cavity surrounded by the placement seat through the feeding channel. At the same time, the residual heat in the riser is transferred to the heating block through the placement seat. The heating block then undergoes an oxidation-reduction reaction and releases a large amount of heat. After that, it can continue to provide heat to the molten metal in the riser, avoiding the molten metal in the riser from solidifying earlier than the molten metal in the cavity due to insufficient temperature, thereby ensuring the quality of the casting. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solution of the specific implementation of the utility model, the following will briefly introduce the drawings required for the specific implementation. In all the drawings, similar elements or components are generally identified by similar reference numerals. In the drawings, each element or component is not necessarily drawn according to the actual scale.

[0017] Figure 1 It is a structural schematic diagram of the riser of the utility model.

[0018] Figure 2 It is a cross-sectional view of the riser of the utility model.

[0019] Figure 3 It is a structural schematic diagram of the thermal insulation riser sleeve of the utility model.

[0020] Figure 4 It is a top view of the thermal insulation riser sleeve of the utility model.

[0021] Figure 5 It is a top view of the riser of the utility model.

[0022] In the figure, 1. upper riser; 2. lower riser; 3. first cavity; 4. second cavity; 5. cover plate; 6. columnar abutment block; 7. truncated cone plug-in block; 8. first hook ring; 9. placement seat; 10. heating block; 11. placement cavity; 12. thermal insulation sealing block; 13. second hook ring; 14. conical exhaust needle; 15. first exhaust channel; 16. second exhaust channel; 17. feeding channel. DETAILED DESCRIPTION

[0023] The following is a detailed description of the embodiments of the technical solution of the utility model in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the utility model, and are therefore only used as examples, and cannot be used to limit the scope of protection of the utility model. Figure 1-Figure 5 as shown in .

[0024] A new type of riser that can improve the exhaust effect includes an upper riser 1 and a lower riser 2, the bottom of the upper riser 1 and the top of the lower riser 2 are integrally formed, a first cavity 3 is formed inside the upper riser 1, and a second cavity 4 is formed inside the lower riser 2, the top of the upper riser 1 is open, a thermal insulation riser sleeve is provided on the top of the upper riser 1, the middle structure of the thermal insulation riser sleeve is pressed against the corresponding position of the top of the upper riser 1 along the horizontal circumferential direction, the lower end of the thermal insulation riser sleeve extends into the first cavity 3, a material connection structure is provided at the middle position of the thermal insulation riser sleeve, and a plurality of exhaust structures are provided at intervals around the vertical center line of the thermal insulation riser sleeve at the outer position of the thermal insulation riser sleeve, the bottom of the lower riser 2 is open, and the bottom opening of the lower riser 2 is used to communicate with the external cavity through a built-in runner.

[0025] The riser of the utility model is an integrally formed structure, the upper part of which is an upper riser 1 with a platform-shaped external shape, and the lower part of which is a lower riser 2 with a columnar external shape. A first cavity 3 is formed inside the upper riser 1, and a second cavity 4 is formed inside the lower riser. Circular openings are provided at the top and bottom of the riser (i.e., at the top of the upper riser 1 and at the bottom of the lower riser 2). The bottom opening of the riser is connected to the cavity through a built-in runner, and molten metal is injected into the inner cavity of the riser (i.e., the first cavity 3 and the second cavity 4) through the top opening of the riser, so as to achieve the purpose of shrinkage compensation.

[0026] After the molten metal is injected into the inner cavity of the riser, the operator covers the top opening of the riser with the insulating riser sleeve through a tool to play a role of insulation and prevent the molten metal in the riser from cooling and solidifying quickly. A material receiving structure and a number of exhaust structures are also provided on the insulating riser sleeve. The lower end of the material receiving structure extends into the inner cavity of the riser together with the lower part of the insulating riser sleeve. When the heat generation of the riser begins to gradually decrease, the operator flexibly adds a heating block 10 to the inside of the material receiving structure through a tool. The heating block 10 is pressed according to the prior art, and its main components are aluminum powder and iron oxide powder, with a ratio of about 1:2.95, and an appropriate amount of combustion aid is added. The heating block 10 moves to the lower end of the material receiving structure under the action of gravity. Since the heating block 10 is close to the internal molten metal at this time, the temperature of the molten metal is transmitted to the heating block 10 through the lower end of the material receiving structure, the combustion aid is ignited, and then the heating block 10 begins to react and releases a large amount of heat to achieve the purpose of continuing to provide heat to the inside of the riser, ensuring that the molten metal can continue to maintain its liquid phase state, thereby continuing to compensate for the shrinkage of large castings.

[0027] The exhaust structures are evenly spaced around the material connection structure (i.e., the vertical center line of the insulation riser sleeve) on the insulation riser sleeve. The exhaust structures are used to discharge excess gas from the riser to avoid porosity defects in the casting. At the same time, the exhaust structures can connect the inner cavity of the riser and the external atmosphere, so that the external atmospheric pressure can act on the metal liquid surface through the exhaust structures, thereby increasing the shrinkage compensation pressure of the metal liquid.

[0028] In any of the above schemes, it is preferred that the thermal insulation riser sleeve includes a support cover plate 5, and a first hook 8 is fixedly installed on the left and right sides of the top surface of the support cover plate 5, respectively. A columnar abutment block 6 is integrally formed in the middle of the bottom surface of the support cover plate 5, and a truncated cone plug-in block 7 is integrally formed at the bottom of the columnar abutment block 6. The material connection structure passes through the support cover plate 5, the columnar abutment block 6 and the truncated cone plug-in block 7 in sequence in the vertical direction, and the lower part of the material connection structure is fixedly arranged on the bottom surface of the truncated cone plug-in block 7, and the exhaust structure passes through the support cover plate 5, the columnar abutment block 6 and the truncated cone plug-in block 7 in sequence in the vertical direction, and the upper part of the exhaust structure is fixedly arranged on the top surface of the support cover plate 5;

[0029] When the thermal insulation riser sleeve is in working condition, the columnar abutment block 6 and the truncated cone-shaped plug-in block 7 jointly pass downward through the top opening of the upper riser 1, the lower part of the material connection structure extends into the first cavity 3, the bottom of the outer periphery of the support cover plate 5 presses against the corresponding position of the top of the upper riser 1, and the circumferential side wall of the columnar abutment block 6 abuts against the vertical inner wall of the top opening of the upper riser 1.

[0030] The heat-insulating riser sleeve is an integrally formed structure, the upper part of which is a disc-shaped cover plate 5, the lower part of the middle of the bottom surface of the cover plate 5 is a cylindrical columnar abutment block 6, the bottom of the columnar abutment block 6 is a truncated cone-shaped truncated cone-shaped plug-in block 7, and the first hook ring 8 is fixedly installed on the left and right sides of the top of the cover plate 5. The operator hooks the first hook ring 8 with a tool and then places it on the top opening of the upper riser 1. At this time, the columnar abutment block 6 and the truncated cone-shaped plug-in block 7 extend to the inside of the first cavity 3 together, and the bottom of the cover plate 5 presses against the corresponding position of the top of the upper riser 1, and the circumferential outer arm of the columnar abutment block 6 fits and abuts against the vertical inner arm of the top opening of the upper riser 1, so as to achieve stable placement of the heat-insulating riser sleeve.

[0031] The material receiving structure passes through the cover plate 5, the columnar abutment block 6 and the truncated cone plug-in block 7 from top to bottom in sequence. The operator puts the heating block 10 into the upper end of the material receiving structure, and then the heating block 10 moves to the lower end under the action of gravity. The lower end is fixedly arranged on the bottom surface of the truncated cone plug-in block 7 and contacts with the air inside the first cavity 3, so as to realize heat exchange with the molten metal in the riser cavity.

[0032] The exhaust structure passes through the cover plate 5, the columnar abutment block 6 and the truncated cone plug-in block 7 from top to bottom, and its upper end extends above the cover plate 5. In this way, even if the cover plate 5 is completely wrapped by the molding sand during the production process, the gas inside the riser can still be discharged through the exhaust structure to ensure the quality of the casting. At the same time, it can also ensure the connection between the inner cavity of the riser and the external atmosphere, and ensure a good shrinkage pressure through atmospheric pressure.

[0033] In any of the above schemes, it is preferred that the material connection structure includes a placement seat 9, the top of the placement seat 9 and the middle of the bottom surface of the truncated cone-shaped plug-in block 7 are integrally formed, the placement seat 9 and the bottom surface of the truncated cone-shaped plug-in block 7 form a placement cavity 11 for placing the heating block 10, and a feeding channel 17 is opened from top to bottom at the corresponding positions of the support cover plate 5, the columnar abutment block 6 and the truncated cone-shaped plug-in block 7, the lower end of the feeding channel 17 is connected to the interior of the placement cavity 11, and the upper end of the feeding channel 17 is connected to the external environment, and also includes a thermal insulation blocking block 12, the lower part of the thermal insulation blocking block 12 is inserted into the inner cavity of the upper end of the feeding channel 17, the bottom of the upper step section of the thermal insulation blocking block 12 cooperates and abuts at the corresponding position of the top surface of the support cover plate 5, and a second hook ring 13 is fixedly installed on the top of the thermal insulation blocking block 12.

[0034] The lower end of the material receiving structure is a placement seat 9. The top of the placement seat 9 and the bottom surface of the truncated cone-shaped plug-in block 7 are integrally formed and together form a placement cavity 11. Heat exchange can occur between the interior of the placement cavity 11 and the interior of the first cavity 3. A feeding channel 17 is provided above the placement seat 9. The feeding channel 17 passes through the cover plate 5, the columnar abutment block 6 and the truncated cone-shaped plug-in block 7 from top to bottom in sequence. The interior of its lower end is connected with the interior of the placement cavity 11, and the upper end opening is arranged in the middle of the top surface of the cover plate 5. The operator puts the heating block 10 into the upper end opening of the feeding channel 17, and then the heating block 10 enters the interior of the placement cavity 11 through the feeding channel 17. Under the heating of the air in the first cavity 3 of the riser, the heating block 10 begins to react and releases heat at the same time, and then the heat continues to heat the air in the first cavity 3 of the riser through the placement seat 9, thereby further heating the molten metal. An insulation sealing block 12 is arranged at the upper opening of the feeding channel 17, and a second hook ring 13 is fixedly installed on the top of the insulation sealing block 12. The operator hooks the insulation sealing block 12 with a special tool to place it at the upper opening of the feeding channel 17, thereby preventing heat from being lost to the external environment through the upper opening of the feeding channel 17.

[0035] In any of the above schemes, it is preferred that the exhaust structure includes a vertically arranged conical exhaust needle 14, a first exhaust channel 15 is formed inside the conical exhaust needle 14, the bottom of the conical exhaust needle 14 is fixedly mounted on one side of the top of the support cover plate 5, and a second exhaust channel 16 is opened from top to bottom at corresponding positions of the support cover plate 5, the columnar abutment block 6 and the truncated cone plug-in block 7, the lower end of the first exhaust channel 15 is connected to the upper end of the second exhaust channel 16 and the two are internally connected, and the lower end of the second exhaust channel 16 is connected to the interior of the first cavity 3.

[0036] The exhaust structure includes a conical exhaust needle 14, which is fixedly mounted on one side of the top surface of the cover plate 5. A second exhaust channel 16 connected to the first exhaust channel 15 inside the conical exhaust needle 14 is provided below the conical exhaust needle 14. The second exhaust channel 16 is opened at corresponding positions of the cover plate 5, the columnar abutment block 6 and the truncated cone plug-in block 7 from top to bottom, and the lower end of the second exhaust channel is connected to the interior of the first cavity 3. During the casting process, the excess gas inside the molten metal can be discharged through the first exhaust channel 15 and the second exhaust channel 16 to avoid quality defects such as pores in the casting.

[0037] In the actual casting process, the molding sand may completely cover the top surface of the cover plate 5, and the presence of the conical exhaust needle 14 can ensure that the channel for exhaust is not blocked by the molding sand, thereby ensuring the exhaust of gas.

[0038] In any of the above schemes, it is preferred that the second cavity 4 is truncated cone-shaped, and the diameter of the upper opening of the second cavity 4 is larger than the diameter of the lower opening. After the casting is completed, the molten metal in the riser cavity and the built-in runner solidifies on the surface of the casting, and then needs to be removed. The utility model sets the second cavity 4 to be truncated cone-shaped, and the diameter of the upper opening of the second cavity 4 is larger than the diameter of the lower opening, so that the riser neck after solidification will be slightly thinner, which can make it more convenient and labor-saving to remove, and at the same time can avoid the defects of damage and lack of meat in the casting body.

[0039] The above shows and describes the basic principle, main features and advantages of the utility model. Those skilled in the art should understand that the utility model is not limited by the above embodiments, and the above embodiments and descriptions are only for explaining the principle of the utility model. Without departing from the spirit and scope of the utility model, the utility model may have various changes and improvements, and these changes and improvements fall within the scope of the utility model to be protected.

[0040] The matters not described in detail in the present invention are all known technologies to those skilled in the art.

Claims

1. A new type of riser that can improve exhaust effect, characterized by: The invention comprises an upper riser (1) and a lower riser (2), wherein the bottom of the upper riser (1) and the top of the lower riser (2) are integrally formed, a first cavity (3) is formed inside the upper riser (1), and a second cavity (4) is formed inside the lower riser (2), the top of the upper riser (1) is open, a heat-insulating riser sleeve is provided on the top of the upper riser (1), a middle structure of the heat-insulating riser sleeve is pressed against a corresponding position on the top of the upper riser (1) along a horizontal circumferential direction, the lower end of the heat-insulating riser sleeve extends into the first cavity (3), a material receiving structure is provided at the middle position of the heat-insulating riser sleeve, and a plurality of exhaust structures are provided at intervals around the vertical center line of the heat-insulating riser sleeve at the outer position of the heat-insulating riser sleeve, the bottom of the lower riser (2) is open, and the bottom opening of the lower riser (2) is used to communicate with an external cavity through a built-in runner.

2. A novel riser capable of improving exhaust effect according to claim 1, characterized in that: The heat-insulating riser sleeve comprises a support cover plate (5), first hooks (8) are fixedly mounted on the left and right sides of the top surface of the support cover plate (5), a columnar abutment block (6) is integrally formed in the middle of the bottom surface of the support cover plate (5), and a truncated cone plug-in block (7) is integrally formed at the bottom of the columnar abutment block (6), the material connection structure passes through the support cover plate (5), the columnar abutment block (6) and the truncated cone plug-in block (7) in sequence in the vertical direction, the lower part of the material connection structure is fixedly arranged on the bottom surface of the truncated cone plug-in block (7), the exhaust structure passes through the support cover plate (5), the columnar abutment block (6) and the truncated cone plug-in block (7) in sequence in the vertical direction, and the upper part of the exhaust structure is fixedly arranged on the top surface of the support cover plate (5); When the heat-insulating riser sleeve is in working condition, the columnar abutment block (6) and the truncated cone-shaped plug-in block (7) jointly pass downward through the top opening of the upper riser (1), the lower part of the material connection structure extends into the first cavity (3), the bottom of the outer periphery of the support cover plate (5) presses against the corresponding position of the top of the upper riser (1), and the circumferential side wall of the columnar abutment block (6) abuts against the vertical inner side wall of the top opening of the upper riser (1).

3. A novel riser capable of improving exhaust effect according to claim 2, characterized in that: The material receiving structure comprises a placement seat (9), the top of the placement seat (9) and the middle of the bottom surface of the truncated cone-shaped plug-in block (7) are integrally formed, the placement seat (9) and the bottom surface of the truncated cone-shaped plug-in block (7) enclose a placement cavity (11) for placing the heating block (10), and a material adding channel (17) is opened from top to bottom at corresponding positions of the support cover plate (5), the columnar abutment block (6) and the truncated cone-shaped plug-in block (7), and the lower portion of the material adding channel (17) is provided with a plurality of holes. The end of the heat-insulating sealing block (12) is connected to the interior of the placement cavity (11), and the upper end of the feeding channel (17) is connected to the external environment. The heat-insulating sealing block (12) is also included. The lower part of the heat-insulating sealing block (12) is inserted into the inner cavity of the upper end of the feeding channel (17). The bottom of the upper step section of the heat-insulating sealing block (12) is matched and abutted against the corresponding position of the top surface of the support cover plate (5). A second hook ring (13) is fixedly installed on the top of the heat-insulating sealing block (12).

4. A novel riser capable of improving exhaust effect according to claim 3, characterized in that: The exhaust structure comprises a vertically arranged conical exhaust needle (14), a first exhaust channel (15) being formed inside the conical exhaust needle (14), the bottom of the conical exhaust needle (14) being fixedly mounted on one side of the top of the support cover plate (5), a second exhaust channel (16) being opened from top to bottom at corresponding positions of the support cover plate (5), the columnar abutment block (6) and the frustum-shaped plug-in block (7), the lower end of the first exhaust channel (15) being connected to the upper end of the second exhaust channel (16) and the interiors of the two being connected, and the lower end of the second exhaust channel (16) being connected to the interior of the first cavity (3).

5. A novel riser capable of improving exhaust effect according to claim 4, characterized in that: The second cavity (4) is in the shape of a truncated cone, and the diameter of the upper opening of the second cavity (4) is greater than the diameter of the lower opening thereof.

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