CN114406161A - A net shape forging die for shaft forgings - Google Patents

Abstract

The utility model relates to a net shaping forging die of axle type forging relates to the forging die field, including last mould and lower mould, the lower mould includes a plurality of half moulds and is used for the mounting of relative position between the fixed half mould, and the die cavity that is used for the shaping forging is offered to the lower mould, and the die cavity is including the concave ring chamber that is used for the shaping bulge loop, and is a plurality of half mould circumference sets up and encloses into the concave ring chamber, adjacent two the half mould is laminated each other, and the binding face of two half moulds is the die joint of two half moulds, the die joint is on a parallel with the central axis of die cavity. This application has the effect that improves utilization ratio of raw materials.

Description

A net shape forging die for shaft forgings

technical field

The present application relates to the field of forging dies, in particular to a net shape forging die for shaft forgings.

Background technique

When the aviation turbofan engine is working, the fan shaft needs to transmit the turbine power to the fan, so that the fan is driven to generate thrust. Therefore, the fan shaft bears a huge torque load during operation. In order to improve the practical life of the fan shaft, the fan shaft is generally a forging. Most of the traditional engine fan shafts are designed with a gradient drum-shaped structure. Die forging is the most economical and efficient production method to produce fan shaft forgings.

At present, the Chinese invention patent with publication number CN201510513390.7 discloses a forging die for a hollow shaft forging with variable cross-section. The forging die includes an upper die and a lower die. After the upper and lower dies are closed, the billet is extruded in the die cavity to form a forging. Then, the upper die returns to the top dead center, and the lower ejection of the forging press is used to eject the forgings from the lower and upper parts, so as to complete the demoulding.

With the development of technology, the fan shaft of the current aviation turbofan engine is a closed bottle-shaped structure. As shown in Figure 1, a forging of the fan shaft of the aviation turbofan engine includes:

The shaft section 100 is cylindrical;

The circular truncated section 101 is in the shape of a truncated truncated cone, and its end with a larger outer diameter is coaxially and fixedly connected to the shaft section 100;

The pillow block section 102 is cylindrical, and is coaxially and fixedly connected to the end of the round table section 101 with the smaller outer diameter, and the outer wall of one end of the pivot block section 102 close to the round table section 101 is coaxially and fixedly connected with a convex ring 103;

The residual material section 104 is coaxially and fixedly connected to the end of the shaft section 100 away from the truncated truncated section 101, and is formed for the accumulation of residual material of the forging blank. The forging is coaxially provided with a central hole 105, and both ends of the central hole 105 penetrate the forging.

The above-mentioned forgings are generally processed into a cylindrical shaft with a center hole by die forging, and then the shape of the above-mentioned forgings is formed by machining.

In view of the above-mentioned related art, the inventors believe that the shape of the above-mentioned forgings retains a lot of residual material, especially the positions of the two axial ends of the convex ring, which leads to the defect of low utilization rate of raw materials.

SUMMARY OF THE INVENTION

In order to alleviate the problem of low utilization rate of raw materials for producing shaft forgings with rings, the present application provides a net-shape forging die for shaft forgings.

The net shape forging die of a shaft forging provided by the application adopts the following technical scheme:

A net-shaped forging die for shaft forgings includes an upper die and a lower die, the lower die includes a plurality of half dies and a fixing piece for fixing the relative positions between the half dies, and the lower die is provided with a die for forming a forging piece Cavity, the mold cavity includes a concave ring cavity for forming a convex ring, a plurality of the half molds are circumferentially arranged and enclosed into a concave ring cavity, two adjacent half molds are attached to each other, and the two half molds are attached to each other. The joint surface is the parting surface of the two half molds, and the parting surface is parallel to the central axis of the mold cavity.

By adopting the above technical solution, the heated blank is placed in the lower mold, the upper mold and the lower mold are closed, the blank is deformed in the mold cavity and an outward pressure is applied to the half molds, and the space between the half molds is kept under the action of the fixing member. relative position to maintain the shape of the cavity. When the blank is formed, the fixing part is disassembled. Without the restriction of the fixing part, the half molds can be separated from each other with the parting surface as the boundary, so as to realize demoulding. Because the parting surface is parallel to the central axis of the cavity, when the half molds are far away from each other, they are along the radial direction of the convex ring, so that the half molds are not easily affected by the convex ring when they are separated from the forging, thus realizing demoulding. The shape of the forging after forging is closer to the shape of the part after the forging, and there is less residual material, which improves the utilization rate of raw materials and reduces the production cost.

Optionally, the fixing member includes a plurality of bolts, and two adjacent half-moulds are fixedly connected by bolts.

By adopting the above technical solution, the adjacent half-moulds are fixed by bolts. When demoulding is required, remove the bolts. The bolts are low cost and easy to operate.

Optionally, a cavity is formed on the fixing piece, and a side wall of one end of the half-mold facing away from the cavity is in contact with the side wall of the cavity of the fixing piece.

By adopting the above technical solution, during forging, the blank is deformed in the die cavity and an outward pressure is applied to the half-die; the half-die is in contact with the side wall of the cavity of the fixing part, so as to balance the force of the outer die during the deformation of the blank. The parts stabilize the position of the mold halves and maintain the shape of the mold cavity. When demoulding, move the fixed part and the half mold in the axial direction and in the opposite direction, so that the half mold is separated from the fixed part, and the fixed part is not limited to the relative position between the half molds, so that the half mold and the forging can be separated, Thereby, demolding is realized, which makes demolding more convenient.

Optionally, the fixing member includes two half-rings, the two half-rings abut and form a ring, and the two half-rings are detachably and fixedly connected.

By adopting the above technical solution, when demoulding, the two half rings are first disassembled, thereby facilitating the separation of the fixing ring and the half die, and further improving the demoulding efficiency of the forging.

Optionally, the fixing member includes an outer mold with a cavity, an inner mold is arranged in the outer mold, the mold cavity is opened in the inner mold or in the inner mold and the outer mold, and the inner mold includes at least The two half molds, the side away from the mold cavity is in contact with the inner wall of the cavity of the outer mold, the outer mold is used to be fixedly connected to the lower working platform of the forging press and the lower ejection pair of the lower working platform Quasi-internal mold.

By adopting the above technical solution, the outer mold is fixedly connected to the lower working platform. After the forging is completed, the lower ejection starts and pushes the inner mold, so that the inner mold is separated from the cavity of the outer mold, and the inner mold is not bound by the outer mold, thereby facilitating the The die halves are separated from the forging. The forging die can be used in conjunction with the existing equipment to make demolding more convenient.

Optionally, the mold cavity further includes a first cylindrical cavity for forming the shaft segment, a circular truncated cavity for forming the circular truncated segment, and a second cylindrical cavity for forming the pedestal segment, and the concave ring cavity is located in the second cylindrical cavity. Between the cylindrical cavity and the truncated truncated cavity and the three are coaxially arranged, the cavity of the outer mold is cylindrical, and its axial length is greater than the axial length of the inner mold, and the inner mold is located in the cavity and in the outer mold The end of the inner mold with the second cylindrical cavity is located at the end of the outer mold, the circular truncated cavity and the second cylindrical cavity are opened in the inner mold, and the cavity of the outer mold does not accommodate the space of the inner mold is the first cylindrical cavity.

By adopting the above technical solution, the shaft section of the forging is formed in the cavity, which can reduce the length of the inner mold, reduce the material used for the inner mold, reduce the cost of the mold, and reduce the weight of the inner mold, which is convenient for the inner mold and the outer mold. It is also easy to install the inner mold in the outer mold.

Optionally, the inner mold further includes a bottom plate, and the bottom plate abuts against the inward-facing sidewall of the half mold and/or the end face facing away from the upper mold.

By adopting the above technical scheme, the bottom end of the die cavity is closed by the bottom plate, and the extrusion of the upper die is used to make both ends of the forging piece under pressure, the end of the forging piece is more flat, and at the same time, the die forging process can be reduced, so that the curing skin detached from the blank can be removed from the inside. The opening at the lower end of the die enters the lower ejection.

Optionally, the half-mold includes a first circular arc plate and a second circular arc plate arranged along the axial direction of the cavity, the axial end of the first circular arc plate and the axial end of the second circular arc plate. Abutting, the first circular arc plate is provided with a circular truncated arc surface, the circular truncated arc surfaces of all the first circular arc plates constitute the side walls of the circular truncated cavity, and all the side walls of the second circular arc plates constitute the first circular arc plate. The side walls of the two cylindrical cavities, the concave ring cavity includes a plurality of arc-shaped grooves opened in the half-mold, and the arc-shaped grooves are opened in the first arc plate and/or the second arc plate.

By adopting the above technical solution, when demoulding, the first arc plate is first separated from the forging, and then the second arc plate is separated from the forging, thereby reducing the pressure between the end wall of the concave ring cavity and the convex ring of the forging, Further, the friction force between the two is reduced, which facilitates demolding of the half-mold.

Optionally, the lower die further includes a drive mechanism that drives the inner die to rotate coaxially with respect to the outer die, and the direction of the torque applied to both ends of the forging due to the rotation of the inner die is the same as the direction of the torque applied to both ends of the forging in the working state. The direction of the torque is the same, and the driving mechanism includes a power assembly for providing power for the rotation of the inner mold and a transmission assembly for transmitting the power of the power assembly to the inner mold;

The power assembly includes an electric motor fixed relative to the outer mold, a driving ring gear that rotates relative to the outer mold, and a transmission gear that meshes with the driving ring gear. The gear is meshed with the driving ring gear, and the transmission gear is rotatably connected to the lower working platform of the forging press and is used to transmit power to the transmission assembly;

The number of the transmission components is the same as the number of the half molds, each transmission component includes a transmission shaft parallel to the central axis of the inner mold, the transmission shaft slides along the direction of approaching or away from the half mold, and the transmission shaft is fixed coaxially An execution gear is connected, the outer wall of the half mold is provided with a plurality of tooth slots to form an incomplete ring gear, the execution gear meshes with the incomplete ring gear, and one end of the transmission shaft is connected with the transmission gear through a coupling. The coupling is a telescopic double universal joint coupling, and the outer mold is fixedly connected with a hydraulic cylinder for driving the transmission shaft to slide.

By adopting the above technical solution, during or after the forging is formed, the power assembly is activated to transmit power to the transmission assembly, and the transmission assembly drives the inner mold to rotate in the outer mold. The inner die rotates relative to the outer die, the inner die drives one end of the forging to rotate, and the forging is twisted, so that the forging streamline after the forging is formed into a spiral shape, and the rotation of the inner die causes the lower die to apply the direction of the torque at both ends of the forging. It is the same as the direction in which the two ends of the forging are subjected to torque in the working state, so the force that the forging is subjected to when working is along the forging streamline. Due to the higher tensile strength of the forging along the forging streamline direction, the fan shaft forging of the above structure has stronger torsional strength in the working environment, reducing the possibility of damage to the forging and improving the life of the forging.

Optionally, each of the transmission shafts is coaxially and fixedly connected with two execution gears, and the two execution gears located on the same transmission shaft are the first execution gear and the second execution gear respectively, and the first circular arc plate and the second circular arc plate is provided with the incomplete gear ring, the incomplete gear ring arranged on the first circular arc plate is the first incomplete gear ring, and the incomplete gear ring arranged on the second circular arc plate is the first incomplete gear ring. The ring is a second incomplete ring gear, the first execution gear meshes with the first incomplete ring gear, the second execution gear meshes with the second incomplete ring gear, and the index circle diameter of the first execution gear It is smaller than the index circle diameter of the second actuating gear.

By adopting the above technical solution, the power assembly drives the transmission shaft to rotate, and the two actuator gears that are coaxially and fixedly connected to the transmission shaft rotate, thereby simultaneously driving the first circular arc plate and the second circular arc plate to rotate. Because the index circle diameter of the first actuator gear is smaller than the index circle diameter of the second actuator gear, the rotation speed of the first circular arc plate is slower than that of the second circular arc plate, and the circular truncated segment of the forging is used as the transition for the torsion of the forging section, to reduce the fracture of the forging due to the excessive torsion angle of the forging.

To sum up, the present application includes at least one of the following beneficial technical effects:

A plurality of mold halves are enclosed to form a mold cavity for forming shaft forgings, the abutment surfaces of the two mold halves are parallel to the central axis of the mold cavity, and the relative position between the mold halves is fixed by a fixing piece. After the blank has been shaped in the cavity, the fixtures are removed, and the mold halves are separated from each other for demolding. Because the abutting surfaces of the two halves are parallel to the central axis of the cavity, when the halves are far away from each other, they follow the radial direction of the convex ring, and when the half die is separated from the forging, it is not easily affected by the convex ring. The shape of the forgings is closer to that of the processed parts, and there is less residual material, thereby improving the utilization rate of raw materials and reducing production costs.

The half-mould includes a first circular arc plate and a second circular arc plate, the first circular arc plate is provided with a circular truncated arc surface, the circular truncated arc surface is used to combine the side walls of the circular truncated cavity, and the side wall of the second circular arc plate is used to form a cylinder On the side wall of the cavity, the concave ring cavity includes a plurality of arc-shaped grooves opened in the mold half, and the arc-shaped grooves are opened in the first circular arc plate and/or the second circular arc plate. When demoulding, the first circular arc plate and the second circular arc plate can be separated from the forging in turn, thereby reducing the frictional force between the half die and the forging, thereby facilitating demoulding.

The lower die also includes a drive mechanism for driving the inner die to rotate relative to the outer die. During or after the forging is formed, the drive mechanism is activated to rotate the inner die relative to the outer die. The inner die drives one end of the forging to rotate, the forging streamline after the forging is formed into a spiral shape, and the force that the forging bears during operation follows the forging streamline, thereby improving the torsional strength of the fan shaft forging in the working environment.

Description of drawings

FIG. 1 is a cross-sectional view of the related art for showing the structure of a fan shaft forging.

FIG. 2 is a cross-sectional view for showing the structure of the forging die in Example 1 of the present application, in which the forging die is installed in a forging press.

FIG. 3 is a cross-sectional view for showing the structure of the lower mold in Example 1 of the present application.

FIG. 4 is an exploded view for showing the fixing member in Embodiment 2 of the present application.

FIG. 5 is a cross-sectional view showing a lower die in Example 2 of the present application.

FIG. 6 is a cross-sectional view for showing a lower die in Example 3 of the present application.

FIG. 7 is a cross-sectional view for showing the structure of the bottom plate in Embodiment 3 of the present application.

FIG. 8 is a cross-sectional view for showing another structure of the bottom plate in Embodiment 3 of the present application.

FIG. 9 is a cross-sectional view for showing another structure of the bottom plate in Embodiment 3 of the present application.

FIG. 10 is a cross-sectional view showing the structure of the lower mold in Example 4 of the present application.

FIG. 11 is an exploded view for showing the structure of the inner mold in Example 4 of the present application.

FIG. 12 is a cross-sectional view showing the driving mechanism in the fifth embodiment of the present application.

FIG. 13 is a structural diagram for showing the driving mechanism in Embodiment 5 of the present application.

FIG. 14 is a cross-sectional view for showing the inner expansion limiting mechanism in the fifth embodiment of the present application.

FIG. 15 is a cross-sectional view showing the extrusion mandrel in Example 6 of the present application.

FIG. 16 is a cross-sectional view for showing a guide groove in Embodiment 6 of the present application.

Description of reference numerals: 100, shaft segment; 101, circular platform segment; 102, axis platform segment; 103, convex ring; 104, residual material segment; 105, central hole; 200, upper die; 201, extrusion block; 203, Extrusion mandrel; 204, guide block; 205, connecting shaft; 206, fixed segment; 207, free segment; 208, rotating segment; 209, wire groove; 300, lower die; 301, cavity; 302, inner die; 303, fixed part; 304, half mold; 305, bottom plate; 306, first cylindrical cavity; 307, circular frustum cavity; 308, concave ring cavity; 309, second cylindrical cavity; 310, residual material cavity; 311, half ring; 312, cavity; 313, first connecting block; 314, second connecting block; 315, first connecting hole; 316, second connecting hole; 317, fixing pin; 318, outer mold; 319, annular accommodating groove; 320 , the first arc plate; 321, the second arc plate; 322, the arc surface of the circular table; 323, the arc groove; 324, the guide groove; 325, the guide track; 400, the driving mechanism; Transmission assembly; 403, electric motor; 404, drive gear; 405, drive ring gear; 406, transmission gear; 407, transmission shaft; 408, first execution gear; 409, second execution gear; 410, first incomplete tooth Ring; 411, Second incomplete ring gear; 412, Chute; 413, Coupling; 414, Slider; 415, Hydraulic cylinder; 416, Accommodating groove; 500, Upper working platform; 501, Lower working platform; 502 , accommodating cavity; 503, upper die moving device; 504, sliding block; 505, cylinder; 600, inner expansion limit mechanism; 601, connecting seat; 602, inner expansion structure; 603, disc part; 604, cylindrical part ; 605, cylindrical cavity; 606, through slot; 607, wedge block; 608, circular table block; 609, spring; 610, connecting column.

Detailed ways

The present application will be further described in detail below in conjunction with accompanying drawings 1-13.

Referring to Figure 1, related art 1: a forging of a fan shaft of an aviation turbofan engine, comprising:

The shaft section 100 is cylindrical;

The circular truncated section 101 is in the shape of a truncated truncated cone, and its end with a larger outer diameter is coaxially and fixedly connected to the shaft section 100;

The pillow block section 102 is cylindrical, and is coaxially and fixedly connected to the end of the round table section 101 with the smaller outer diameter, and the outer wall of one end of the pivot block section 102 close to the round table section 101 is coaxially and fixedly connected with a convex ring 103;

The residual material section 104 is coaxially and fixedly connected to the end of the shaft section 100 away from the truncated truncated section 101, and is formed for the accumulation of residual material of the forging blank. The forging is coaxially provided with a central hole 105, and both ends of the central hole 105 penetrate the forging.

The embodiment of the present application discloses a net-shape forging die for a shaft forging, which is used for producing the forging described in the related art.

Example 1:

Referring to FIG. 2 , the forging die includes an upper die 200 and a lower die 300 . The upper die 200 is installed on the upper working platform 500 of the forging press, and the lower die 300 is provided with a cavity 301 for forming a forging, and is installed on the lower working platform 501 of the forging press. When working, the forging press lifts the upper die 200, and then places the heated blank on the lower die 300. The forging press drives the upper die 200 to move to the lower die 300, and the upper die 200 presses the blank into the cavity 301. When the die 200 and the lower die 300 are closed, the blank is extruded into a forging in the cavity 301 of the lower die 300 .

Referring to FIG. 3 , the lower mold 300 includes a plurality of half molds 304 , and the plurality of half molds 304 are arranged in a circumferential direction and enclose the above-mentioned mold cavity 301 . The two adjacent half-moulds 304 are bonded to each other, and the bonding surface between the half-moulds 304 is the parting surface of the two half-moulds 304 . The parting surface is parallel to the central axis of the mold cavity 301 and arranged vertically. The number of the half molds 304 is three, or four, and the number of the half molds 304 may be greater than or equal to two.

Referring to FIG. 3 , the mold cavity 301 includes a first cylindrical cavity 306 , a truncated circular cavity 307 , a concave ring cavity 308 and a second cylindrical cavity 309 in sequence, and the four are arranged coaxially.

Referring to FIG. 3 , the first cylindrical cavity 306 is used for forming the shaft segment 100 , and its inner wall is a cylindrical surface. The truncated truncated cavity 307 is used to form the truncated truncated section 101, and its inner wall is a truncated truncated surface. The larger inner diameter end of the circular frustum cavity 307 communicates with the first cylindrical cavity 306 , and the inner diameter of the larger end of the circular frustum cavity 307 is smaller than or equal to the inner diameter of the first cylindrical cavity 306 . The end of the inner wall of the circular frustum cavity 307 with the smaller inner diameter communicates with the concave ring cavity 308 . The concave ring cavity 308 is used to form the convex ring 103 . The lower end of the concave ring cavity 308 communicates with the second cylindrical cavity 309 , and the second cylindrical cavity 309 is used for forming the pillow block section 102 .

Referring to FIG. 3 , in order to accommodate the residual material of the forging blank, the die cavity 301 further includes a residual material cavity 310 communicating with the upper end of the first cylindrical cavity 306 , and the residual material after the blank is compressed and deformed remains in the residual material cavity 310 and forms the residual material. Section 104. The inner diameter of the residual material cavity 310 is larger than the inner diameter of the first cylindrical cavity 306 , and a chamfer is provided at the connection between the side wall of the residual material cavity 310 and the side wall of the first cylindrical cavity 306 .

Referring to FIG. 3 , the lower mold 300 further includes a fixing member 303 for fixing the relative positions between the half molds 304 . The fixing member 303 and the mold half 304 are detachably connected. When the forging die is working, the relative positions between the half-die 304 are maintained under the action of the fixing member 303 to maintain the shape of the die cavity 301 . After the forging is formed, the fixing member 303 is disassembled, and then the mold half 304 is moved radially away from the forging to realize demoulding. Because the direction in which the half-die 304 is separated from the forging is along the radial direction of the convex ring 103, the half-die 304 is not easily affected by the convex ring 103 when it is separated from the forging.

Referring to FIG. 3 , in this embodiment, the fixing member 303 includes a plurality of bolts, and two adjacent half-moulds 304 are fixedly connected by two bolts. When demoulding is required, the bolts can be removed.

Referring to FIG. 2 , the upper die 200 includes an extrusion block 201 and an extrusion mandrel 203 . Both are installed on the upper die moving device 503 of the upper work platform 500 of the forging press. The upper die moving device 503 is used to move the horizontal position of the pressing block 201 and the pressing mandrel 203 . The upper die moving device 503 can move the extrusion block 201 to be just above the lower die 300 , or move the extrusion mandrel 203 to just above the lower die 300 . The extrusion block 201 is cylindrical, and the outer diameter of its lower end is equal to the inner diameter of the residual material cavity 310 . The extrusion mandrel 203 is cylindrical, and is coaxially slidably connected with a guide block 204 , and the outer diameter of the guide block 204 is equal to the inner diameter of the residual material cavity 310 .

Referring to FIG. 2 , the upper mold moving device 503 includes a sliding block 504 that is horizontally slidably connected to the upper working platform 500 and an air cylinder 505 for driving the sliding block 504 to move. The sliding block 504 is in the shape of a rectangular strip, and the extrusion block 201 and the extrusion mandrel 203 are fixedly connected to the sliding block 504 . The cylinder body of the cylinder 505 is fixedly connected to the upper working platform 500, and the cylinder 505 pushes the sliding block 504 to slide along its length direction.

The implementation principle of Example 1 is as follows: first place the heated blank in the residual material cavity 310, control the upper die moving device 503 to move the extrusion block 201 to just above the lower die 300, and then start the forging press to make the extrusion block 201 and the extrusion block 201. The lower mold 300 is closed to extrude the blank into the first cylindrical cavity 306 , the circular frustum cavity 307 , the concave ring cavity 308 and the second cylindrical cavity 309 , and the blank is extruded into the mold cavity 301 . The forging press drives the extrusion block 201 to move upwards so as to be separated from the lower die 300 .

The upper die moving device 503 is controlled to move the extrusion mandrel 203 to just above the lower die 300 . Start the forging press to close the extrusion mandrel 203 and the lower die 300 to form the central hole 105 of the forging.

Then, the fixing member 303 is disassembled, and the mold halves 304 are separated from each other along the parting surface, thereby realizing demoulding. Because the parting surface is parallel to the central axis of the cavity 301, when the mold halves 304 are far away from each other, they are along the radial direction of the convex ring 103, so that the mold halves 304 are not easily affected by the convex ring 103 when they are separated from the forging, so that the forging belt is not easily affected by the convex ring 103. The shaft parts of the convex ring 103 can reduce the machining allowance, improve the utilization rate of raw materials, and reduce the production cost.

Example 2:

Referring to FIG. 4 , the difference between Embodiment 2 and Embodiment 1 lies in the fixing member 303 . The fixing member 303 includes two half-rings 311, one end of one half-ring 311 is hinged with one end of the other half-ring 311, the ends of the two half-rings 311 away from the hinge point abut each other, and a detachable fixed connection is realized by setting a quick-release structure. . The two half rings 311 form a ring, and the space between the rings is a cavity 312 .

4 , the quick release structure includes a first connecting block 313 fixedly connected to one half ring 311 and a second connecting block 314 fixedly connected to the other half ring 311 . The first connecting block 313 defines a first connecting hole 315 . The second connection block 314 defines a second connection hole 316 . The central axes of the first connection hole 315 and the second connection hole 316 are both parallel to the central axis of the cavity 312 . When the ends of the two half-rings 311 away from the hinge point abut each other, the first connecting hole 315 and the second connecting hole 316 are coaxially arranged.

Referring to FIG. 4 , the quick release structure further includes a fixing pin 317 , the fixing pin 317 passes through the first connecting hole 315 and the second connecting hole 316 at the same time, so as to limit the positions of the first connecting block 313 and the second connecting block 314 . Pulling out the fixing pin 317 realizes the disassembly of one end of the two half rings 311 . The ends of the two half rings 311 away from the hinge point can also be fixed by bolts, and it is only necessary to realize the detachable and fixed connection of the ends of the two half rings 311 away from the hinge point.

Referring to FIG. 5 , all the mold halves 304 are inserted into the fixing member 303 , and the outer wall of the mold halves 304 is arc-shaped. When all the mold halves 304 are arranged circumferentially and surround the mold cavity 301 , the mold halves 304 face away from the mold cavity 301 at one end. The side wall of the mold is the outer wall of the half mold 304 , and the outer walls of all the half molds 304 form a complete cylindrical surface and are in contact with the inner wall of the cavity 312 of the fixing member 303 . The fixing member 303 is used to balance the outward force exerted on the mold half 304 during the deformation of the blank in the mold cavity 301 , thereby stabilizing the position of the mold half 304 and maintaining the shape of the mold cavity 301 .

Embodiment 2 is different from Embodiment 1 in that: after the blank is formed, the bolts or fixing pins 317 are first disassembled, and then the half ring 311 is rotated in the opposite direction, thereby realizing the disassembly of the fixing member 303 . The fixing member 303 no longer restricts the relative positions between the half-moulds 304, so that the half-moulds 304 and the forgings can be separated, thereby realizing demoulding and making demolding more convenient.

Example 3:

Referring to FIG. 6 , the difference between Embodiment 3 and Embodiment 2 lies in the fixing member 303 , and the fixing member 303 includes an outer mold 318 with a cavity 312 formed therein. The cavity 312 is in the shape of a vertical cylinder and penetrates both ends of the outer mold 318 along its axial direction. Inside the cavity 312 of the outer mold 318, an inner mold 302 is inserted, and the inner mold 302 is provided with a mold cavity 301 for forming a fan shaft forging in the related art.

Referring to FIG. 6 , the outer die 318 is fixedly connected to the lower working platform 501 of the forging press by bolts, and the lower ejection of the lower working platform 501 is aligned with the inner die 302 located in the outer die 318 .

6 , the inner mold 302 includes at least two mold halves 304 as described in Embodiment 2, and all the mold halves 304 are circumferentially arranged in the cavity 312 of the outer mold 318 and enclose the mold cavity 301 . The side wall of the half mold 304 facing away from the mold cavity 301 is in contact with the inner wall of the cavity 312 of the outer mold 318 .

Referring to FIG. 7 , the inner mold 302 further includes a bottom plate 305 for closing the lower end opening of the mold cavity 301 . The bottom plate 305 is circular and the diameter of the bottom plate 305 is equal to the inner diameter of the second cylindrical cavity 309 .

8 , in another embodiment, the side wall of the bottom plate 305 is fitted with the side wall of the cavity 312 of the outer mold 318 , and the lower end surface of the half mold 304 abuts the upper end surface of the bottom plate 305 .

Referring to FIG. 9 , in another embodiment, an annular accommodating groove 319 is formed on the upper end surface of the bottom plate 305 , and the lower end of the mold half 304 is placed in the annular accommodating groove 319 . The side wall of the half mold 304 is abutted with the side wall of the cavity 312 of the outer mold 318 , and the inner wall of the half mold 304 is abutted with the side wall of the annular accommodating groove 319 .

Embodiment 3 is different from Embodiment 2 in that the implementation principle is: the outer mold 318 is fixedly connected to the lower working platform 501, and after the forging is completed, the lower ejection starts and pushes the inner mold 302 to move upward relative to the outer mold 318, so that the inner mold 302 Released from cavity 312 of outer mold 318 . The die half 304 without the fixed relative position of the outer die 318 facilitates separation from the forging. The forging die can be used in conjunction with the existing equipment to make demolding more convenient.

Example 4:

10 , the difference between Embodiment 4 and Embodiment 3 is that the axial length of the inner mold 302 is smaller than the axial length of the outer mold 318 , and the inner mold 302 is located at a lower position inside the outer mold 318 .

Referring to FIG. 10 , a mold cavity 301 is opened in the lower mold 300 . The truncated truncated cavity 307 used for molding the truncated truncated section 101 , the concave ring cavity 308 used for molding the convex ring 103 , and the second cylindrical cavity 309 used for molding the boss section 102 are opened in the inner mold 302 . The upper end of the outer mold 318 is provided with the residual material cavity 310 , and the residual material cavity 310 and the cavity 312 are coaxially arranged. The space between the cavity 312 from the residual material cavity 310 to the circular frustum cavity 307 is the first cylindrical cavity 306 .

The difference between Embodiment 4 and Embodiment 3 also lies in the mold half 304 .

Referring to FIGS. 10 and 11 , the mold half 304 includes a first arc plate 320 and a second arc plate 321 distributed along the axial direction of the mold cavity 301 . The first arc plate 320 is located above the second arc plate 321 , and the lower end surface of the first arc plate 320 is attached to the upper end surface of the second arc plate 321 .

11 , the inner wall of the first circular arc plate 320 is provided with a circular truncated arc surface 322 . The inner wall of the second arc plate 321 is the side wall of the second cylindrical cavity 309 . The concave ring cavity 308 includes a plurality of arc-shaped grooves 323 opened in the mold half 304 , and the arc-shaped grooves 323 are located at the lower end of the inner wall of the first circular arc plate 320 . The arc-shaped groove 323 can also be located at the upper end of the inner wall of the second arc plate 321 , or half of the arc-shaped groove 323 is located at the lower end of the first arc plate 320 and the other half is located at the upper end of the second arc plate 321 .

Referring to FIG. 11 , due to the split design of the first circular arc plate 320 and the second circular arc plate 321, the convex ring 103 of the forging will not be stuck in the concave ring cavity 308 during demolding, and the mold halves can be separated more easily 304 and forgings.

Referring to FIG. 11 , also because the first circular arc plate 320 and the second circular arc plate 321 are designed as separate bodies, the upward pressing force exerted on the first circular arc plate 320 when the convex ring 103 is formed from the blank may cause the first circular arc plate 320 to be compressed. The arc plate 320 slides upward, and this phenomenon is called "floating". The "floating" of the first arc plate 320 will cause the shape of the die cavity 301 to change, thereby causing the forging to be unqualified.

Referring to FIG. 11 , the design of the circular truncated arc surface 322 just alleviates the above problem. When the blank is pressed into the die cavity 301 , it first squeezes the circular truncated arc surface 322 , and then squeezes into the concave ring cavity 308 . When the blank presses the truncated arc surface 322, two component forces are formed. One component is a horizontal component along the radial direction of the mold cavity 301 and directed out of the mold cavity 301 , and the other component is a vertical downward vertical force. The vertical component force exerts a downward force on the first circular arc plate 320 , so that the first circular arc plate 320 and the second circular arc plate 321 are in close contact, and can balance the impact of the blank on the first circular arc when the convex ring 103 is formed The upward pressing force exerted by the plate 320 relieves the problem of "floating" of the first arc plate 320 during the extrusion molding process of the blank.

Example 5:

Referring to FIG. 12 , the difference between Embodiment 5 and Embodiment 4 is that the lower mold 300 further includes a driving mechanism 400 that drives the inner mold 302 to rotate coaxially with respect to the outer mold 318 .

12 , during or after the forging is formed, the driving mechanism 400 is activated to drive the inner die 302 to rotate in the outer die 318 . The inner mold 302 rotates relative to the outer mold 318, the inner mold 302 drives the lower end of the forging to rotate, and the forging is twisted, so that the forging streamline after the forging is formed is helical.

The rotation direction of the inner die 302 relative to the outer die 318 is set according to the force condition of the forging in the working state. The direction in which the two ends of the forging receive torque in the lower die 300 is the same as the direction in which the two ends receive torque in the working state.

The working state of the fan shaft machined from the forging in this embodiment is that the turbine drives the fan shaft to rotate clockwise, the driving force of the turbine acts on the shaft section 100 of the fan shaft, and the shaft block section 102 of the fan shaft is used to install the fan. At this time, the direction of torque received by the shaft section 100 of the fan shaft is clockwise. When the fan shaft drives the fan to rotate, the fan will experience air resistance. Air resistance is transmitted to the pillow block section 102 of the fan shaft through the fan, and the direction of the resistance is counterclockwise. When forging the fan shaft forging, the inner mold 302 is driven to rotate counterclockwise by the driving mechanism 400 .

12 , the direction in which the two ends of the forging receive torque in the lower die 300 is the same as the direction in which the two ends receive torque in the working state, so the direction of the forging streamline of the forging is the same as the direction of the force that the forging is subjected to during operation. Due to the higher tensile strength of the forging along the forging streamline direction, the fan shaft forging of the above structure has stronger torsional strength in the working environment, reducing the possibility of damage to the forging and improving the life of the forging.

12 , the driving mechanism 400 includes a power assembly 401 for providing power for the rotation of the inner mold 302 and a transmission assembly 402 for transmitting the power of the power assembly 401 to the inner mold 302 . The number of the transmission components 402 is three, and they are arranged circumferentially along the outer wall of the inner mold 302 .

Referring to FIGS. 12 and 13 , an accommodating cavity 502 for accommodating the power assembly 401 is opened on the upper end of the lower working platform 501 . The power assembly 401 includes an electric motor 403 fixedly connected to the lower working platform 501 . The main shaft of the electric motor 403 is arranged vertically upward, and a driving gear 404 is fixedly connected to it coaxially.

12 and 13 , the power assembly 401 further includes a driving ring gear 405 meshing with the driving gear 404 , the driving ring gear 405 is rotatably connected to the lower working platform 501 through a plane bearing, and is coaxially arranged with the inner mold 302 . The lower working platform 501 is rotatably connected with a transmission gear 406 meshing with the driving gear ring 405 .

Referring to FIG. 12 and FIG. 13 , the outer wall of the outer mold 318 is provided with an accommodating groove 416 for accommodating the transmission assembly 402 . The transmission assembly 402 includes a vertical transmission shaft 407 , the lower end of which passes through the outer mold 318 and extends into the accommodating cavity 502 . The lower end of the transmission shaft 407 is connected with the transmission gear 406 through the coupling 413 . The transmission shaft 407 is coaxially and fixedly connected with two execution gears, and the two execution gears are a first execution gear 408 and a second execution gear 409 respectively. The outer walls of the first circular arc plate 320 and the second circular arc plate 321 are provided with a plurality of tooth slots in the circumferential direction to form an incomplete gear ring. The incomplete ring gear of the first circular arc plate 320 is the first incomplete ring gear 410 , and the first incomplete ring gear 410 meshes with the first execution gear 408 . The incomplete ring gear of the second circular arc plate 321 is the second incomplete ring gear 411 , and the second incomplete ring gear 411 meshes with the second execution gear 409 . The pitch circle diameter of the first actuator gear 408 is smaller than the pitch circle diameter of the second actuator gear 409 . When the power assembly 401 drives the transmission shaft 407 to rotate, the rotational speed of the first actuator gear 408 and the second actuator gear 409 are the same, but the linear velocity of the outer diameter of the first actuator gear 408 is smaller than the linear velocity of the outer diameter of the second actuator gear 409, so As a result, the rotational speed of the first circular arc plate 320 is smaller than the rotational speed of the second circular arc plate 321 . During the torsion process of the forging, the circular truncated section 101 of the forging serves as a transitional section for the forging torsion, which reduces the occurrence of fracture of the forging due to an excessively large torsion angle of the forging.

Referring to FIGS. 12 and 13 , in order to reduce the interference when the inner mold 302 of the execution gear is separated from the outer mold 318 , the transmission shaft 407 and the outer mold 318 are arranged in a sliding manner. The upper and lower side walls of the accommodating groove 416 are provided with sliding grooves 412 for the transmission shaft 407 to slide. The extension line of the longitudinal direction of the chute 412 passes through the center line of the mold cavity 301 . The lower chute 412 penetrates the lower end surface of the outer mold 318 and communicates with the accommodating cavity 502 . A sliding block 414 is slidably connected in the chute 412 along its length, and the upper end of the transmission shaft 407 passes through the sliding block 414 and is rotatably connected to the sliding block 414 by installing a rolling bearing. The lower end of the transmission shaft 407 passes through another sliding block 414 and is rotatably connected with the sliding block 414 by installing a rolling bearing. The coupling 413 used for connecting the transmission shaft 407 with the transmission gear 406 is a telescopic double universal joint coupling.

12 and 13 , the transmission assembly 402 further includes a hydraulic cylinder 415 for driving the transmission shaft 407 to slide. The cylinder body of the hydraulic cylinder 415 is fixedly connected to the outer mold 318 , and the transmission shaft 407 is passed through the piston rod of the hydraulic cylinder 415 and the two are rotatably connected.

Referring to Figure 14, the upper working platform 500 is also provided with an inner expansion limiting mechanism 600, which is used to limit the rotation of the upper end portion of the forging, so as to relieve the inner die 302 to drive the lower end of the forging to rotate, the entire forging rotates accordingly, and cannot be applied to the forging. Torque problem.

Referring to FIG. 14 , the inner expansion limiting mechanism 600 includes a connecting seat 601 and an inner expansion structure 602 disposed in the connecting seat 601 .

The connecting seat 601 includes a disc portion 603 and a cylindrical portion 604 that is coaxially and fixedly connected to the disc portion 603 . The cylindrical portion 604 is provided with a cylindrical cavity 605 for accommodating the inner expansion structure 602 . The cylindrical portion 604 is provided with three rectangular through grooves 606 in the circumferential direction, and the through grooves 606 communicate with the cylindrical cavity 605 .

Referring to FIG. 14 , the diameter of the disc portion 603 is slightly smaller than the diameter of the residual material cavity 310 , and the diameter of the cylindrical portion 604 is slightly smaller than the diameter of the central hole 105 .

Referring to FIG. 14 , the inner expansion structure 602 includes three wedge-shaped blocks 607 , and the wedge-shaped blocks 607 slide in the through grooves 606 one by one. The outer wall of the wedge-shaped block 607 is a vertical arc surface, and the inner wall is an inclined arc surface. The upper end of the inner wall of the wedge-shaped block 607 is inclined outward, so that the wedge-shaped block 607 becomes thicker and thicker along the vertical downward direction.

14 , the inner expansion structure 602 further includes a truncated truncated block 608, which is located in the cylindrical cavity 605 and whose small end face (the small end face is the end face with a smaller diameter of the truncated truncated block 608) faces downward. The diameter of the large end face of the truncated truncated block 608 (the large end face is the end face with the larger diameter of the truncated truncated block 608 ) is equal to the diameter of the cylindrical cavity 605 . The truncated side wall of the truncated truncated block 608 and the inner wall of the wedge-shaped block 607 are parallel and fit.

14 , when the circular truncated block 608 moves downward, the circular truncated block 608 pushes the wedge-shaped block 607 to move out of the connecting seat 601 . In order to facilitate pushing the circular truncated block 608 , the inner expansion structure 602 further includes a connecting column 610 that is coaxially and fixedly connected to the large end face of the circular truncated block 608 . The diameter of the connecting post 610 is smaller than the diameter of the large end face of the circular truncated block 608 . The connecting column 610 passes through the cylindrical portion 604 and the disc portion 603 in sequence, and extends to the outside of the connecting seat 601 . The connecting column 610 is used for fixedly connecting with the sliding block 504 of the upper working platform 500 .

Referring to FIG. 14 , a spring 609 is also disposed in the cylindrical cavity 605 , one end of the spring 609 abuts against the bottom of the cylindrical cavity 605 , and the other end abuts against the small end face of the truncated truncated block 608 .

The implementation principle that embodiment 5 is different from embodiment 4 is:

During the forging forming process or after the forging is formed, the sliding block 504 is moved so that the inner expansion limiting mechanism 600 is located directly above the lower die 300 . Then, the upper die 200 drives the inwardly rising limiting mechanism 600 to press down. The cylindrical portion 604 is inserted through the center hole 105 of the forging, and when the disc portion 603 is in contact with the upper end surface of the forging, the connecting seat 601 does not move downward. However, the connecting column 610 continues to drive the circular platform block 608 to move downward.

When the circular truncated block 608 moves downward, it will push the wedge block 607 to move outward. The wedge-shaped block 607 moves outward and abuts against the inner wall of the central hole 105 of the forging, thereby clamping and fixing the forging. In addition, when the circular platform block 608 moves downward, the spring 609 will be compressed, and under the action of the spring 609, a downward pressure will be applied to the connecting seat 601, and the forging will be formed by the disc portion 603. Therefore, the upper end of the forging is fixed by the inner expansion limit mechanism 600 .

Then, the electric motor 403 is started, and the electric motor 403 drives the driving ring gear 405 to rotate through the driving gear 404 . The transmission gear 406 meshing with the driving ring gear 405 also rotates therewith. The transmission gear 406 transmits the torque to the drive shaft 407 through the telescopic double universal joint. The actuator gear that is coaxially and fixedly connected to the transmission shaft 407 also rotates accordingly. The rotation of the execution gear drives the inner mold 302 to rotate on the outer mold 318 . The inner mold 302 drives one end of the forging to rotate, and the forging is twisted, so that the forging streamline after the forging is formed into a spiral shape, which improves the torsional strength of the fan shaft forging in the working environment, reduces the possibility of damage to the forging, and improves the forging. life.

Example 6:

12, the difference between Embodiment 6 and Embodiment 5 is that the extrusion mandrel 203 includes:

The connecting shaft 205 is vertically rotatably connected to the sliding block 504, and a stepping motor is fixedly connected to the sliding block 504, and the stepping motor is used to drive the connecting shaft 205 to rotate;

The fixed section 206 is sleeved on the connecting shaft 205 and is fixedly connected with the sliding block 504;

The free section 207 is sleeved on the connecting shaft 205 and is rotatably connected with the connecting shaft 205, and is located below the fixed section 206;

The rotating section 208 is fixedly connected to the lower end of the connecting shaft 205 and abuts against the lower end of the free section 207, and the lower end of the rotating section 208 is in the shape of a bullet. The lower end of the rotating segment 208 is provided with a plurality of wire grooves 209 in the circumferential direction. The wire groove 209 extends along the axial direction of the rotating section 208 .

The outer wall of the mold half 304 is provided with a plurality of helical guide grooves 324, and the helical direction of the guide grooves 324 is counterclockwise and helical upward. A plurality of helical guide rails 325 are defined on the inner wall of the outer mold 318 , and the guide rails 325 are matched with the guide grooves 324 . During demolding, during the upward movement of the inner mold 302, under the action of the guide rails 325 and the guide grooves 324, the inner mold 302 rotates counterclockwise. At this time, the stepping motor drives the connecting shaft 205 to rotate, and the rotating segment 208 fixedly connected to the connecting shaft 205 also rotates, and the rotating speed is the same as the rotating speed of the inner mold 302 .

Driven by the rotating section 208 and the inner die 302, the lower end of the forging rotates, and the forging is twisted, so that the forging streamline after the forging is formed into a spiral shape, which improves the torsional strength of the fan shaft forging in the working environment and reduces the damage of the forging. possibility to increase the life of the forgings.

The above are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. Therefore: all equivalent changes made according to the structure, shape and principle of the present application should be included in the protection scope of the present application. Inside.

Claims (10)

1. The net forming forging die for the shaft forging is characterized in that: including last mould (200) and lower mould (300), lower mould (300) include a plurality of half moulds (304) and be used for fixed half mould (304) between the mounting (303) of relative position, die cavity (301) that are used for the shaping forging are offered to lower mould (300), and die cavity (301) are including concave ring chamber (308) that are used for shaping bulge loop (103), and are a plurality of half mould (304) circumference sets up and encloses into concave ring chamber (308), adjacent two half mould (304) are laminated each other, and the fitting surface of two half moulds (304) is the die joint of two half moulds (304), the die joint is on a parallel with the central axis of die cavity (301).

2. The net forming forging die of the shaft forging of claim 1, wherein: the fixing piece (303) comprises a plurality of bolts, and two adjacent half moulds (304) are fixedly connected through the bolts.

3. The net forming forging die of the shaft forging of claim 1, wherein: the fixing piece (303) is provided with a cavity (312), and the side wall of one end of the half mold (304) departing from the mold cavity (301) is abutted against the side wall of the cavity (312) of the fixing piece (303).

4. The net forming forging die of the shaft forging of claim 3, wherein: the fixing piece (303) comprises two semi-rings (311), the two semi-rings (311) are abutted and enclosed to form a ring, and the two semi-rings (311) are detachably and fixedly connected.

5. The net forming forging die of the shaft forging of claim 3, wherein: the fixing piece (303) comprises an outer die (318) provided with a cavity (312), an inner die (302) is arranged in the outer die (318), the die cavity (301) is arranged in the inner die (302) or arranged in the inner die (302) and the outer die (318), the inner die (302) comprises at least two half dies (304), one side, far away from the die cavity (301), of each half die (304) is abutted to the inner wall of the cavity (312) of the outer die (318), and the outer die (318) is used for being fixedly connected to a lower working platform (501) of the forging press and the lower ejection of the lower working platform (501) is aligned to the inner die (302).

6. The net forming forging die of the shaft forging of claim 5, wherein: the mould cavity (301) further comprises a first cylindrical cavity (306) for moulding the shaft section (100), a frustum cavity (307) for moulding the frustum section (101) and a second cylindrical cavity (309) for moulding the frustum section (102), the concave ring cavity (308) is positioned between the second cylindrical cavity (309) and the circular truncated cone cavity (307) and is coaxially arranged with the second cylindrical cavity, the cavity (312) of the outer die (318) is cylindrical, an axial length of which is greater than an axial length of an inner mold (302), the inner mold (302) being located within the cavity (312) and at one end of an outer mold (318), one end of the inner die (302) provided with the second cylindrical cavity (309) is positioned at the end part of the outer die (318), the circular table cavity (307) and the second cylindrical cavity (309) are arranged on the inner die (302), the space of the cavity (312) of the outer mold (318) which does not contain the inner mold (302) is a first cylindrical cavity (306).

7. The net forming forging die of the shaft forging according to claim 5 or 6, wherein: the inner mold (302) further comprises a bottom plate (305), and the bottom plate (305) abuts against an inward side wall of the mold half (304) and/or an end surface facing away from the upper mold (200).

8. The net forming forging die of the shaft forging of claim 6, wherein: the half mould (304) comprises a first arc plate (320) and a second arc plate (321) which are axially arranged along the mould cavity (301), one axial end of the first arc plate (320) is abutted to one axial end of the second arc plate (321), a circular truncated cone arc surface (322) is arranged on the first arc plate (320), the circular truncated cone arc surfaces (322) of all the first arc plates (320) form the side wall of the circular truncated cone cavity (307), the side wall of all the second arc plates (321) form the side wall of the second cylindrical cavity (309), the concave ring cavity (308) comprises a plurality of arc grooves (323) which are arranged on the half mould (304), and the arc grooves (323) are arranged on the first arc plate (320) and/or the second arc plate (321).

9. The net forming forging die of the shaft forging of claim 8, wherein: the lower die (300) further comprises a driving mechanism (400) for driving the inner die (302) to coaxially rotate relative to the outer die (318), the direction of torque applied to two ends of the forge piece by the lower die (300) due to the rotation of the inner die (302) is the same as the direction of torque applied to two ends of the forge piece in the working state, and the driving mechanism (400) comprises a power assembly (401) for providing power for the rotation of the inner die (302) and a transmission assembly (402) for transmitting the power of the power assembly (401) to the inner die (302);

the power assembly (401) comprises an electric motor (403) fixed relative to the outer die (318), a driving gear ring (405) rotating relative to the outer die (318), and a transmission gear (406) meshed with the driving gear ring (405), a driving gear (404) is coaxially and fixedly connected with a main shaft of the electric motor (403), the driving gear (404) is meshed with the driving gear ring (405), and the transmission gear (406) is rotatably connected to a lower working platform (501) of the forging press and is used for transmitting power to the transmission assembly (402);

the quantity of transmission subassembly (402) is the same with the quantity of half mould (304), and every transmission subassembly (402) is including transmission shaft (407) that is on a parallel with interior mould (302) the central axis, transmission shaft (407) slide along being close to or keeping away from half mould (304) direction, transmission shaft (407) coaxial fixedly connected with executive gear, half mould (304) outer wall has been seted up a plurality of tooth's socket and has been formed incomplete ring gear, executive gear and incomplete ring gear meshing, transmission shaft (407) one end is connected with transfer gear (406) through setting up shaft coupling (413), shaft coupling (413) are the two universal joint shaft couplings of retractable, external mould (318) fixedly connected with is used for driving hydraulic cylinder (415) that transmission shaft (407) slided.

10. The net forming forging die of a shaft forging of claim 9, wherein: every the coaxial fixedly connected with of transmission shaft (407) is two execute the gear, and two execute gears that are located same transmission shaft (407) are first execute gear (408) and second execution gear (409) respectively, first circular arc board (320) and second circular arc board (321) are provided with incomplete ring gear, set up in incomplete ring gear of first circular arc board (320) is first incomplete ring gear (410), set up in incomplete ring gear of second circular arc board (321) is second incomplete ring gear (411), first execution gear (408) and first incomplete ring gear (410) meshing, incomplete ring gear (409) and second incomplete ring gear (411) meshing are executed to the second, the reference circle diameter of first execution gear (408) is less than the reference circle diameter of second execution gear (409).

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