CN113699518B

CN113699518B - Low-temperature preparation device for silicon carbide coating on metal surface

Info

Publication number: CN113699518B
Application number: CN202110992466.4A
Authority: CN
Inventors: 丁柳宁; 周李伟; 陈凯
Original assignee: Zhejiang Liufang Carbon Technology Co ltd
Current assignee: Zhejiang Liufang Semiconductor Technology Co.,Ltd.
Priority date: 2021-08-27
Filing date: 2021-08-27
Publication date: 2023-06-20
Anticipated expiration: 2041-08-27
Also published as: CN113699518A

Abstract

The invention discloses a low-temperature preparation device of a silicon carbide coating on a metal surface, which is characterized in that: including hollow reaction chamber, go up the sealing piece, lower sealing piece, twine on the lateral wall of reaction chamber has induction coil, be provided with gas transmission mouth and gas vent on last sealing piece, outside at the reaction chamber is provided with the coating mixing box, be provided with the coating delivery pump in the coating mixing box, be provided with the conveying pipeline and the row material pipe with the reaction chamber intercommunication between coating mixing box and lower sealing piece, be provided with the feed back pipe with the reaction chamber intercommunication between coating mixing box and the last sealing piece, be provided with the check valve on the conveying pipeline, be provided with two solenoid valves on the row material pipe, the intercommunication has the manometer on the feed back pipe, be provided with pressure adjustable relief valve on the feed back pipe. The invention provides a low-temperature preparation device for a silicon carbide coating on a metal surface, which enables an ultra-thick dense silicon carbide coating to be formed on the metal surface, ensures the uniformity of heating of a workpiece, and reduces the temperature required by preparation.

Description

Low-temperature preparation device for silicon carbide coating on metal surface

Technical Field

The invention relates to the field of preparation of silicon carbide coatings, in particular to a low-temperature preparation device of a silicon carbide coating on a metal surface.

Background

Silicon carbide is widely used in the fields of aerospace, aviation, microelectronics, automobiles, laser, mining industry, atomic energy and the like due to its high hardness, high wear resistance, high bending strength, excellent oxidation resistance, acid and alkali corrosion resistance and high-temperature mechanical properties. And the high-purity silicon carbide coating plays an important role in high-temperature protection, oxidation resistance and corrosion resistance in the fields. The compact silicon carbide coating is prepared on the surface of the metal, so that the metal material can be prevented from being etched by gases such as hydrogen, oxygen, nitride and the like in a high-temperature environment. However, the existing silicon carbide coating has thin thickness, the silicon carbide coating needs to be heated outside during sintering, the temperature required for heating is high, meanwhile, the problem that a metal piece is heated unevenly exists, and the metal piece is usually required to be rotationally arranged in a heated box body, so that the metal piece rotates in the heating process, and the heating uniformity is improved.

Disclosure of Invention

The invention aims to solve the technical problem of the prior art, and provides a low-temperature preparation device for a silicon carbide coating on a metal surface, so that an ultra-thick and dense silicon carbide coating is formed on the metal surface, and meanwhile, the heating uniformity of a workpiece is ensured, and the temperature required by preparation is reduced.

The technical scheme adopted for solving the technical problems is as follows: a low-temperature preparation device for a silicon carbide coating on a metal surface is characterized in that: the device comprises a hollow reaction chamber, an upper sealing block arranged on the upper part of the reaction chamber in a sliding manner, and a lower sealing block arranged on the lower part of the reaction chamber in a sliding manner, wherein the reaction chamber, the upper sealing block and the lower sealing block are made of non-conductive materials, an induction coil is wound on the outer side wall of the reaction chamber and connected with an induction power supply, a gas delivery port and a gas exhaust port communicated with the reaction chamber are arranged on the upper sealing block, the gas delivery port is connected with a pressurizing pump, the gas exhaust port is connected with the gas exhaust pump, a paint mixing box is arranged outside the reaction chamber, a paint delivery pump is arranged in the paint mixing box, a material delivery pipe and a material discharge pipe communicated with the reaction chamber are arranged between the paint mixing box and the lower sealing block, a material return pipe communicated with the reaction chamber is arranged between the paint mixing box and the upper sealing block, the paint delivery pump is connected with the material delivery pipe, a one-way valve for limiting paint to flow to the reaction chamber from the paint mixing box is arranged on the material discharge pipe, two-way electromagnetic valves are respectively a communication position and a non-communication position, a pressure relief valve is arranged on the material return pipe.

And in addition, the paint conveying pump is a variable pump.

The lower sealing block is fixed on the base, the upper sealing block is fixed on the top plate, a lifting cylinder connected with the upper sealing block is arranged on the top plate, a middle sleeve is sleeved outside the reaction chamber and fixedly connected with the reaction chamber, a left ear extends from the left side of the middle sleeve, a right ear extends from the right side of the middle sleeve, a left slide way is arranged on the left ear, a right slide way is arranged on the right ear, a left slide block is arranged in the left slide way in a sliding manner, a right slide block is arranged in the right slide way in a sliding manner, a first connecting rod group is hinged between the top plate and the left slide block, a second connecting rod group is hinged between the base and the left slide block, a third connecting rod group is hinged between the top plate and the right slide block, and a fourth connecting rod group is hinged between the base and the right slide block.

And the first connecting rod group, the second connecting rod group, the third connecting rod group and the fourth connecting rod group are respectively composed of two connecting rods sharing the same rotation shaft.

Still improve, be provided with mixing mechanism in the coating mixing box, mixing mechanism includes the mixing seat, the mixing motor, the crank that links to each other with the mixing motor output, connect the planetary gear on the crank outer end, with planetary gear center pin fixed connection's head rod, be fixed in the first axis of rotation on the head rod outer end, be fixed in the second connecting rod on the first axis of rotation, be fixed in the second axis of rotation on the second connecting rod, the axis of second axis of rotation and planetary gear center pin coincidence, head rod and second connecting rod circumference projection coincidence, be formed with a ring gear with planetary gear meshing on the mixing seat, first axis of rotation is gone up to overlap and is equipped with first pendulum rod and the second pendulum rod of bifurcation each other, be equipped with first stop collar and second stop collar on the second pivot cover each other, first pendulum rod passes first stop collar, the second pendulum rod passes the second stop collar, it has first connecting sleeve to articulate between the outer end of first pendulum rod and the outer end of third pendulum rod, it has the adapter sleeve to articulate to have between the outer end of second pendulum rod and the fourth, first adapter sleeve and the stirring sleeve is equipped with to the second.

And in addition, the upper side surface of the lower sealing block is provided with a groove.

And the paint in the paint mixing box is formed by mixing silicon carbide powder, an organic solvent, an adhesive and a sintering agent according to a certain proportion.

Further improved, the sintering agent is carbon or boron.

Compared with the prior art, the invention has the advantages that: in the preparation process of the silicon carbide coating on the metal surface, an upper sealing block or a lower sealing block is opened, a metal workpiece is placed in a reaction chamber, the silicon carbide powder, an organic solvent, an adhesive and a sintering agent are mixed and ground according to a certain proportion, finally, the paint is placed in a paint mixing box, an exhaust pump works, gas in the reaction chamber is exhausted to form vacuum, meanwhile, the pressure value of a pressure relief valve is set, the paint in the paint mixing box is conveyed into the reaction chamber by the paint conveying pump, in the paint conveying process, a two-position two-way electromagnetic valve is in a non-communication working position, the one-way valve can limit paint backflow in the reaction chamber, the reaction chamber is filled with paint until the pressure on a material return pipe is larger than the pressure value set by the pressure relief valve, redundant paint is refluxed into the paint mixing box through the material return pipe, the paint in the reaction chamber is maintained, the coating can be fully distributed on each position on the surface of the metal workpiece, places which cannot be or are not easy to spray in place are avoided, the coating uniformity is greatly improved, after a period of pressure retention, the coating conveying pump stops working, the two-position two-way electromagnetic valve is switched to a communication working position, meanwhile, the pressurizing pump gradually introduces inert gas into the reaction chamber through the gas transmission port, the coating in the reaction chamber is gradually discharged into the coating mixing box through the discharge pipe, then the pressure of 2500-4000Pa is kept in the reaction chamber by the cooperative work of the gas discharge pump and the pressurizing pump, meanwhile, the induction coil outside the reaction chamber is introduced with high-frequency alternating current, as the upper sealing block, the reaction chamber and the lower sealing block are all made of non-conductive materials, the upper sealing block, the reaction chamber and the lower sealing block can not heat under the action of the induction coil, and only the interior of the metal workpiece in the reaction chamber is heated, the method comprises the steps of heating a metal workpiece to 350-400K, evaporating an organic solvent, forming a compact silicon carbide powder film on the surface of the metal, then decompressing the reaction chamber to keep the pressure of the reaction chamber at 1000-1500Pa, adjusting the temperature in the reaction chamber to 1500-1700K, heating for 20-40min to form an ultra-thick dense silicon carbide coating, and directly heating the interior of the metal workpiece by using the principle of induction heating, so that the coating transfers heat from inside to outside and performs sintering, thereby ensuring the heating uniformity of the workpiece, simultaneously, more fully and directly utilizing a heat source, and reducing the temperature required by preparation.

Drawings

FIG. 1 is a schematic diagram of a low temperature apparatus for producing a silicon carbide coating on a metal surface in accordance with an embodiment of the present invention;

FIG. 2 is a schematic diagram of the connection structure of the upper block, the reaction chamber and the lower block according to the embodiment of the present invention;

fig. 3 is a schematic structural view of a mixing mechanism in an embodiment of the present invention.

Detailed Description

The invention is described in further detail below with reference to the embodiments of the drawings.

As shown in fig. 1 to 3, the low temperature preparation apparatus for a silicon carbide coating on a metal surface in the present embodiment comprises a reaction chamber 12, an upper block 11, a lower block 13, a base 32, a top plate 31, a first link group 361, a second link group 362, a third link group 363, a fourth link group 364, an induction coil 2, an induction power source 21, a pressurizing pump 4, an exhaust pump 5, a paint mixing tank 9, a mixing mechanism, a paint delivery pump 7, a one-way valve 81, a two-position two-way electromagnetic valve 82, a pressure gauge 84, and a pressure relief valve 83.

The reaction chamber 12 is hollow and is of a hollow structure, the upper sealing block 11 is arranged on the upper part of the reaction chamber 12 in a sliding manner, the lower sealing block 13 is arranged on the lower part of the reaction chamber 12 in a sliding manner, the reaction chamber 12, the upper sealing block 11 and the lower sealing block 13 are made of non-conductive materials, an induction coil 2 is wound on the outer side wall of the reaction chamber 12, the induction coil 2 is connected with an induction power supply 21, a gas transmission port 41 and a gas exhaust port 51 which are communicated with the reaction chamber 12 are arranged on the upper sealing block 11, the gas transmission port 41 is connected with the pressurizing pump 4, the gas exhaust port 51 is connected with the gas exhaust pump 5, a paint mixing box 9 is arranged on the outside of the reaction chamber 12, a paint conveying pump 7 is preferably a variable pump, the control of paint conveying flow is realized, a conveying pipe 61 and a discharge pipe 62 which are communicated with the reaction chamber 12 are arranged between the paint mixing box 9 and the lower sealing block 13, a return pipe 63 which is communicated with the reaction chamber 12 is arranged between the paint mixing box 9 and the upper sealing block 11, the paint conveying pump 7 is connected with the conveying pipe 61, the two pressure relief valves 82 are respectively arranged on the two pressure relief valves 82 which are communicated with the two pressure-adjustable valves 82, and the two pressure-adjustable valves 82 are respectively arranged on the two pressure-adjustable valves 82.

In addition, in order to facilitate the opening of the reaction chamber 12, the sliding arrangement structure of the upper sealing block 11 and the lower sealing block 13 is that, as shown in fig. 2, the lower sealing block 13 is fixed on the base 32, the upper sealing block 11 is fixed on the top plate 31, the lifting cylinder 37 connected with the upper sealing block is arranged on the top plate 31, an intermediate sleeve 33 is sleeved outside the reaction chamber 12, the intermediate sleeve 33 is fixedly connected with the reaction chamber 12, a left ear 34 extends from the left side of the intermediate sleeve 33, a right ear 35 extends from the right side of the intermediate sleeve 33, a left slideway 341 is arranged on the left ear 34, a right slideway 351 is arranged on the right ear 35, a left slider 342 is arranged in the left slideway 341 in a sliding manner, a right slider 352 is arranged in the right slideway 351, a first link group 361 is hinged between the top plate 31 and the left slider 342, a second link group 362 is hinged between the base 32 and the left slider 342, a third link group 363 is hinged between the top plate 31 and the right slider 352, and a fourth link group 364 is hinged between the base 32 and the right slider 352. When a metal workpiece is required to be placed into the reaction chamber 12, the lifting cylinder 37 is retracted, the top plate 31 pulls up the upper sealing block 11, meanwhile, under the action of the four connecting rod groups, the middle sleeve 33 also moves upwards, so that the lower sealing block 13 can be opened, a groove can be formed in the upper side face of the lower sealing block 13 for facilitating material placement, the metal workpiece is placed in the groove, or the metal workpiece is placed on the placement frame of the reaction chamber 12 by arranging a placement frame in the reaction chamber 12 and entering from the top or the bottom of the reaction chamber 12, after the metal workpiece is placed, the lifting cylinder 37 is reset and extends out, and the upper sealing block 11 and the lower sealing block 13 realize the up-down position of the reaction chamber 12.

Further, in order to improve the stability of the linkage transmission, the first linkage 361, the second linkage 362, the third linkage 363 and the fourth linkage 364 are respectively composed of two links sharing the same rotation axis.

In addition, in order to improve the uniformity of the coating and prevent the coating from depositing, a mixing mechanism is arranged in the coating mixing box 9, as shown in fig. 3, the mixing mechanism comprises a mixing seat 91, a mixing motor, a crank connected with the output end of the mixing motor, a planetary gear 92 connected on the outer end of the crank, a first connecting rod 931 fixedly connected with the central shaft of the planetary gear 92, a first rotating shaft fixed on the outer end of the first connecting rod 931, a second connecting rod 932 fixed on the first rotating shaft, a second rotating shaft 94 fixed on the second connecting rod 932, the axis of the second rotating shaft 94 coincides with the central shaft of the planetary gear 92, the first connecting rod 31 and the second connecting rod 932 are projected and coincide circumferentially, an inner gear ring 911 meshed with the planetary gear 92 is formed on the mixing seat 91, a first swing rod 951 and a second swing rod 952 which are mutually bifurcated are sleeved on the first rotating shaft 94, a first limit sleeve 971 and a second limit sleeve 92 are arranged on the mixing seat 91 in a relative rotation manner, the first swing rod 951 passes through the first limit sleeve 951 and the outer end of the first swing rod 952 and the second limit sleeve 952 passes through the outer end of the first connecting sleeve 952, and the first limit sleeve 952 and the second swing rod 952 passes through the outer end of the first limit sleeve 952 and the second limit sleeve 952 are respectively arranged on the first end of the first connecting sleeve 953 and the second swing sleeve 952. The mixing motor drives the crank to rotate, the crank drives the planetary gear 92 to rotate around the annular gear 911 of the mixing seat 91, and the planetary gear 92 drives the four swing rods to swing synchronously through two connecting rods, specifically, the first swing rod 951 and the third swing rod 953 swing in a group, the second swing rod 952 and the fourth swing rod 954 swing in a group, and the two swing rods oppositely arranged swing in a reciprocating mode, so that paint in the paint mixing box 9 is fully mixed, and precipitation of the paint is avoided.

Finally, the invention also provides a low-temperature preparation method of the silicon carbide coating on the metal surface, which comprises the following steps:

step S1, mixing and grinding titanium carbide powder, an organic solvent, an adhesive and a sintering agent according to a certain proportion, and finally placing the paint into a paint mixing box 9;

step S2, opening the upper sealing block 11 or the lower sealing block 13, and placing a metal workpiece in the reaction chamber 12;

step S3, the pressure maintaining pressure when the paint on the surface of the metal workpiece in the reaction chamber is set by setting the pressure relief pressure of the pressure relief valve 83, the paint in the paint mixing box 9 is conveyed into the reaction chamber 12 by the paint conveying pump 7, in the paint conveying process, the two-position two-way electromagnetic valve 82 is in a non-communication working position, the one-way valve 81 can limit the paint in the reaction chamber 12 to flow back, the reaction chamber 12 is filled with the paint until the pressure on the material return pipe 63 is larger than the pressure value set by the pressure relief valve 83, and the redundant paint flows back into the paint mixing box 9 through the material return pipe 63, so that the paint in the reaction chamber 12 can be maintained in all positions on the surface of the metal workpiece, and the paint is maintained for 10-30min;

step S4, the paint delivery pump 7 stops working, the two-position two-way electromagnetic valve 82 is switched to a communication working position, meanwhile, the pressurizing pump 4 gradually introduces inert gas into the reaction chamber 12 through the gas delivery port 41, paint in the reaction chamber 12 is gradually discharged into the paint mixing box 9 through the discharge pipe 62, then, the pressure intensity of 2500-4000Pa is kept in the reaction chamber 12 by the cooperative work of the exhaust pump 5 and the pressurizing pump 4, meanwhile, the induction coil 2 outside the reaction chamber 12 is introduced with high-frequency alternating current, the inside of a metal workpiece in the reaction chamber 12 is heated to the temperature of 350-400K, evaporation of organic solvent in the paint is realized, and a compact silicon carbide powder film is formed on the metal surface;

and S5, decompressing the reaction chamber 12 to ensure that the pressure in the reaction chamber 12 is kept at 1000-1500Pa, and simultaneously, regulating the temperature in the reaction chamber 12 to 1500-1700K, and heating for 20-40min to form the ultra-thick dense silicon carbide coating.

Wherein, preferably, the sintering agent is carbon or boron.

In summary, in the preparation process of the silicon carbide coating on the metal surface, the upper sealing block 11 or the lower sealing block 13 is opened, the metal workpiece is placed in the reaction chamber 12, the silicon carbide powder, the organic solvent, the adhesive and the sintering agent are mixed and ground according to a certain proportion, finally, the paint is placed in the paint mixing box 9, the exhaust pump 5 works, the gas in the reaction chamber 12 is exhausted to form vacuum, bubbles are prevented from occurring in the process of inputting the paint into the reaction chamber 12, meanwhile, the pressure value of the pressure relief valve 83 is set, the paint conveying pump 7 conveys the paint in the paint mixing box 9 into the reaction chamber 12, in the process of conveying the paint, the two-position two-way electromagnetic valve 82 is in a non-communicated working position, the one-way valve 81 can limit the paint backflow in the reaction chamber 12, the paint is filled in the reaction chamber 12 until the pressure on the feed back pipe 84 is larger than the pressure value set by the pressure relief valve 83, the redundant paint flows back into the paint mixing box 9 through the feed back pipe 84 to realize the pressure maintaining of the paint in the reaction chamber 12, so that all positions on the surface of a metal workpiece can be fully covered with the paint, places which cannot be or are not easy to spray in place are not existed, the uniformity of paint coating is greatly improved, after the paint is maintained for a period of time, the paint conveying pump 7 stops working, the two-position two-way electromagnetic valve 82 is switched to a communicating working position, meanwhile, the pressurizing pump 4 gradually introduces inert gas into the reaction chamber 12 through the gas conveying port 41, the paint in the reaction chamber 12 is gradually discharged into the paint mixing box 9 through the discharge pipe 62, then the pressure of 2500-4000Pa is kept in the reaction chamber 12 by the cooperative work of the exhaust pump 5 and the pressurizing pump 4, meanwhile, the induction coil 2 outside the reaction chamber 12 is introduced with high-frequency alternating current, and the upper sealing block 11, the reaction chamber 12 and the lower sealing block 13 are all made of non-conductive materials, the upper sealing block 11, the reaction chamber 12 and the lower sealing block 13 can not generate heat under the action of the induction coil 2, only the interior of the metal workpiece in the reaction chamber 12 is heated, so that the metal workpiece is heated to the temperature of 350-400K, the evaporation of an organic solvent is realized, a compact silicon carbide powder film is formed on the metal surface, then the pressure in the reaction chamber 12 is reduced, the interior of the reaction chamber 12 is kept at the pressure of 1000-1500Pa, meanwhile, the temperature in the reaction chamber 12 is regulated to 1500-1700K, and the temperature is heated for 20-40min, so that an ultra-thick dense silicon carbide coating is formed.

Claims

1. A low-temperature preparation device for a silicon carbide coating on a metal surface is characterized in that: comprises a hollow reaction chamber (12), an upper sealing block (11) arranged on the upper part of the reaction chamber (12) in a sliding way, a lower sealing block (13) arranged on the lower part of the reaction chamber (12) in a sliding way, wherein the reaction chamber (12), the upper sealing block (11) and the lower sealing block (13) are made of non-conductive materials, an induction coil (2) is wound on the outer side wall of the reaction chamber (12), the induction coil (2) is connected with an induction power supply (21), a gas delivery port (41) and a gas outlet (51) which are communicated with the reaction chamber (12) are arranged on the upper sealing block (11), the gas delivery port (41) is connected with a pressurizing pump (4), the gas outlet (51) is connected with a gas discharge pump (5), a coating material delivery pump (7) is arranged in the coating material mixing box (9) outside the reaction chamber (12), a material delivery pipe (61) and a material discharge pipe (62) which is communicated with the reaction chamber (12) are arranged between the coating material mixing box (9) and the lower sealing block (13), a material delivery pipe (61) which is communicated with the reaction chamber (12) is arranged between the coating material mixing box (9) and the upper sealing block (11) and the coating material mixing box (61) is connected with the coating material (61), a two-position two-way electromagnetic valve (82) is arranged on the discharge pipe (62), two working modes of the two-position two-way electromagnetic valve (82) are a communication position and a non-communication position respectively, a pressure gauge (84) is communicated with the feed back pipe (63), and a pressure relief valve (83) with adjustable pressure is arranged on the feed back pipe (63);

the paint conveying pump (7) is a variable pump, so that the paint conveying flow is controlled;

the sliding arrangement structure of the upper sealing block (11) and the lower sealing block (13) is that the lower sealing block (13) is fixed on a base (32), the upper sealing block (11) is fixed on a top plate (31), a lifting cylinder (37) connected with the upper sealing block is arranged on the top plate (31), a middle sleeve (33) is sleeved outside a reaction chamber (12), the middle sleeve (33) is fixedly connected with the reaction chamber (12), a left lug (34) extends from the left side of the middle sleeve (33), a right lug (35) extends from the right side of the middle sleeve (33), a left slideway (341) is arranged on the left lug (34), a right slideway (351) is arranged on the right lug (35), a left slideway (342) is arranged in a sliding manner, a right slideway (352) is arranged in a sliding manner, a first connecting rod group (361) is hinged between the top plate (31) and the left slideway (342), a second connecting rod group (362) is hinged between the base (32) and the left slideway (342), a third connecting rod group (364) is hinged between the top plate (31) and the right slideway (352); when a metal workpiece is required to be placed into the reaction chamber (12), the lifting cylinder (37) is retracted, the top plate (31) pulls up the upper sealing block (11), and meanwhile, under the action of the four connecting rod groups, the middle sleeve (33) also moves upwards, so that the lower sealing block (13) can be opened, a groove can be formed in the upper side surface of the lower sealing block (13) for facilitating discharging, the metal workpiece is placed in the groove, or the metal workpiece enters from the top or bottom of the reaction chamber (712) through the arrangement of the arrangement frame in the reaction chamber (12), the metal workpiece is placed on the arrangement frame of the reaction chamber (12), and after the metal workpiece is placed, the lifting cylinder (37) is reset and extends out, and the upper sealing block (11) and the lower sealing block (13) realize the sealing of the upper part and the lower part of the reaction chamber (12); the paint in the paint mixing box (9) is formed by mixing silicon carbide powder, an organic solvent, an adhesive and a sintering agent according to a certain proportion, wherein the sintering agent is carbon or boron;

the first connecting rod group (361), the second connecting rod group (362), the third connecting rod group (363) and the fourth connecting rod group (364) are respectively composed of two connecting rods sharing the same rotation shaft;

the paint mixing box (3) is internally provided with a mixing mechanism, the mixing mechanism comprises a mixing seat (91), a mixing motor, a crank connected with the output end of the mixing motor, a planet gear (92) connected to the outer end of the crank, a first connecting rod (931) fixedly connected with the central shaft of the planet gear (92), a first rotating shaft fixed on the outer end of the first connecting rod (931), a second connecting rod (932) fixed on the first rotating shaft, a second rotating shaft (94) fixed on the second connecting rod (932), the axis of the second rotating shaft (94) coincides with the central shaft of the planet gear (92), the first connecting rod (931) and the central shaft of the planet gear (932) are circumferentially projected to coincide, an inner gear ring (911) meshed with the planet gear (92) is formed on the mixing seat (91), a first swing rod (951) and a second swing rod (952) which are mutually forked are sleeved on the first rotating shaft, a third swing rod (953) and a fourth swing rod (972) which are mutually forked are sleeved on the second rotating shaft (94), a first swing rod (951) and a second swing rod (972) which penetrate through the first swing rod (971) and the second swing rod (972) which penetrate through the first swing rod (972), a first connecting sleeve (971) is hinged between the outer end of the first swing rod (951) and the outer end of the third swing rod (953), a second connecting sleeve (972) is hinged between the outer end of the second swing rod (952) and the outer end of the fourth swing rod (954), and stirring blades are respectively sleeved on the first connecting sleeve (971) and the second connecting sleeve (972).