Harmonic reducer flexible gear pre-forming multi-force-source progressive die

Abstract

The multi-force-source progressive die is used for machining a material sheet into a flexible gear blank, the flexible gear blank comprises a barrel and a flange, a barrel opening in one end of the barrel is connected with the flange, a feeding channel is formed between an upper die base and a lower die base, and when the upper die base and the lower die base are closed, the feeding channel is connected with the flange. The first female die assembly and the first male die assembly pre-stretch a material sheet to form a boss, the second female die assembly and the second male die assembly conduct contour shaping on the boss formed through pre-stretching, and the third female die assembly and the third male die assembly punch a center hole in the boss subjected to contour shaping. The multi-force-source male die assembly and the multi-force-source female die assembly apply shearing force and drawing force which are opposite to each other to a material piece with a punched center hole, a flange is punched through the shearing force to achieve blanking, and a boss with the center hole is drawn into a cylinder through the drawing force. According to the scheme, through the synergistic effect of multiple force sources, die abrasion is reduced, the service life is prolonged, and the size precision and shape precision of the flexible gear blank can be guaranteed.

Description

Technical Field

[0001] This application relates to the technical field of manufacturing molds for the flexspline of a harmonic reducer, and particularly to a multi-force-source progressive die for the initial forming of a harmonic reducer flexspline. Background Art

[0002] A harmonic reducer is a precision speed reduction device that uses the elastic deformation of a flexible element to transmit motion and power. It consists of a wave generator, a flexspline, and a rigid gear. The wave generator is assembled with flexible bearings to cause the flexspline to produce controllable elastic deformation, which meshes with the rigid gear to transmit motion and power through gear transmission. The core of the harmonic reducer lies in the elastic deformation of the flexspline, thereby achieving a high reduction ratio, high precision, and high rigidity. The cap-type flexspline is a relatively common type among all types of flexsplines. During its forming process, a flexspline blank including a thin-walled cylinder and a flange needs to be pre-processed, then tooth profile machining is performed on the thin-walled cylinder, and finally a complete flexspline is formed through a series of steps such as heat treatment and precision machining.

[0003] In traditional processes, the flexspline blank is mainly processed by forging. Specifically, the bar stock is formed through steps such as cutting, normalizing, forging, and rough turning. This processing method has a large amount of material surplus, many processes, low raw material utilization rate, high machining cost and labor cost, low processing efficiency, is not suitable for mass production, and it is difficult to ensure product consistency. Therefore, the forging process of the flexspline blank has gradually been replaced by the stamping process. The stamping process has the following advantages compared with the forging process: it can utilize molds and presses to achieve continuous and high-speed automated production. During stamping, only the strip or sheet metal needs to be fed into the stamping equipment, and multiple processes such as blanking, stretching, and punching can be quickly completed according to the preset program, manufacturing a large number of flexspline blanks in a short time.

[0004] The forming quality of the flexspline directly affects the performance of the harmonic reducer. Although there are many advantages in machining the flexspline blank by stamping, there are also some technical problems, as follows: There are difficulties in manufacturing high-precision dies. The shape and dimensional accuracy requirements of the flexspline are extremely high, and its tooth profile accuracy, profile tolerance and other indicators directly affect the performance of the harmonic reducer. Therefore, the stamping die must have very high manufacturing accuracy; In order to achieve one-step forming or multi-step stamping of the flexspline blank, the die structure is often relatively complex, and the coordinated work of multiple systems such as die guiding, positioning, and unloading needs to be considered at the same time; During the stamping process, the material flow directly affects the forming quality of the flexspline blank. Due to the complex shape of the flexspline, the material flow in the die is uneven, which easily leads to defects such as local thinning, wrinkling or cracking. For example, during the stretching process, if the flow resistance of the material is too large, the stretched part will become thinner or even crack; If the flow resistance is too small, wrinkling will occur. Therefore, it is necessary to precisely control the material flow; The stamping process of the flexspline blank usually requires multiple processes to complete, such as blanking, stretching, punching, sizing, etc. The coordination between processes is very crucial. Any problem in one process will affect the quality of the entire flexspline blank. It is necessary to reasonably arrange the sequence and process parameters of each process to ensure smooth connection between processes and avoid quality problems; During the stretching and blanking processes, problems such as sheet deformation and poor dimensional accuracy are likely to occur, affecting the quality of the flexspline.

[0005] Therefore, a flexspline blank forming die that can realize continuous production, improve production efficiency and forming accuracy is needed. Summary of the Invention

[0006] The present application provides a multi-force-source continuous die for primary forming of a harmonic reducer flexspline to improve or solve the technical problems of low production efficiency, low forming accuracy, and poor production quality existing in forming the flexspline blank by the existing stamping method.

[0007] The technical solution adopted in the present application is as follows:

[0008] A multi-force-source progressive die for the initial forming of a flexible gear of a harmonic reducer, which is used to process a sheet into a flexible gear blank. The flexible gear blank includes a cylinder body and a flange. One end of the cylinder body is connected to the flange at the cylinder opening. The progressive die includes an upper die base and a lower die base. A feeding channel is formed between the upper die base and the lower die base. The upper die base is sequentially provided with a first female die assembly, a second female die assembly, a third female die assembly and a multi-force-source male die assembly along the feeding direction. The lower die base is sequentially provided with a first male die assembly, a second male die assembly, a third male die assembly and a multi-force-source female die assembly along the feeding direction. When the upper die base and the lower die base are closed, the first female die assembly and the first male die assembly pre-stretch the sheet to form a boss. The second female die assembly and the second male die assembly perform contour shaping on the boss formed by pre-stretching. The third female die assembly and the third male die assembly punch a central hole on the boss after contour shaping. The multi-force-source male die assembly and the multi-force-source female die assembly apply mutually reverse shearing force and tensile force to the sheet with a central hole punched, cut out the flange by the shearing force to realize blanking, and stretch the boss with a central hole into a cylinder body by the tensile force.

[0009] In this technical solution, through different female die assemblies and male die assemblies sequentially arranged on the upper die base and the lower die base along the feeding direction, a series of operations such as pre-stretching, contour shaping, punching a central hole, blanking by punching and stretching the cylinder body of the sheet can be realized, and the sheet is gradually processed into a flexible gear blank, forming a multi-station progressive die. Multiple stamping processes are integrated on a set of dies, enabling the flexible gear blank to complete the forming of multiple features in one stamping stroke, reducing the handling and waiting time between processes, realizing the continuous production of the initial forming of the flexible gear, improving production efficiency, reducing the material transfer and positioning error between processes. All processes are completed within a single die, avoiding the tolerance stacking caused by multiple positionings, improving the coaxiality (concentricity of the cylinder body and the flange) of the flexible gear blank, and ensuring the accuracy and consistency of the flexible gear blank. During the continuous processing of the progressive die, the cold work hardening effect of the sheet material is dispersed to each process, avoiding the increase in local brittleness caused by single severe deformation. This progressive die can minimize the waste of materials, make full use of the sheet material, make the material utilization rate reach a relatively high level, and reduce production costs. Shearing and stretching are carried out simultaneously. The shearing force punches the flange, and the tensile force forms the cylinder body. The multi-force sources act synergistically. The reverse shearing force and tensile force offset part of the punching vibration, reduce die wear, and extend the service life, which can ensure the dimensional accuracy and shape accuracy of the flexible gear blank. The dimension deviation of the stamped flexible gear blank is small, the surface quality is good, and the subsequent machining allowance is small, which is beneficial to improving the quality and performance of the final product.

[0010] The multi-force source punch assembly includes a hollow blanking punch, and the multi-force source die assembly includes a hollow blanking die, a hollow reverse punching die and a stretching punch which are nested in sequence from outside to inside; when the hollow blanking punch and the hollow blanking die are closed, the hollow blanking punch applies a downward shearing force to the blank, the hollow blanking die applies an upward shearing force to the blank, the hollow reverse punching die applies an upward reverse punching force to the blank and moves downward synchronously with the hollow blanking punch to punch out a flange through the upward shearing force, the downward shearing force and the reverse punching force, and the stretching punch moves upward into the hollow cavity of the hollow blanking punch and passes through the central hole to stretch the boss into a cylinder together with the hollow blanking punch.

[0011] In this technical solution, the structures of the multi-force source punch assembly and the multi-force source die assembly are specifically defined. Through the cooperation of the hollow blanking punch, the hollow blanking die, the hollow reverse punching die and the stretching punch, shearing forces, reverse punching forces and stretching forces in opposite directions are applied to the blank. The shearing forces and reverse punching forces in opposite directions are used to punch out a flange to achieve blanking, and the stretching force stretches the boss with a central hole into a cylinder. This multi-force source action mode can more accurately complete the forming of the flexspline blank, improve the forming quality, realize the synchronization of flange blanking and cylinder stretching, and optimize the dynamic force transmission: the nested design of the hollow blanking punch and the stretching punch makes the stretching force transmission path more direct and reduces energy loss (traditionally, it is necessary to perform blanking step by step and then stretching, resulting in energy loss). The stretching punch immediately enters the hollow cavity for stretching after blanking to prevent the position deviation of the punched flange due to springback; the coordinated movement of the hollow reverse punching die provides a reverse punching force to assist blanking, and the resultant force direction of the reverse punching force and the shearing force is controllable, making the blanking fracture surface of the flange smoother and reducing burrs (which is crucial for the transmission accuracy of the flexspline).

[0012] The upper die holder is provided with a blank holding tooth surrounding the hollow blanking punch, and the blank holding tooth is set to have a V-shaped cross-section. During the process of the hollow blanking punch and the hollow blanking die punching out a flange, the blank holding tooth presses into the surface of the blank to apply a downward pressure to the blank that presses against the hollow blanking die, and apply a side pressure to the blank that has an included angle with the downward pressure.

[0013] In this technical solution, a pressure tooth surrounding the hollow punching punch is arranged on the upper die seat, and the pressure tooth has a V-shaped cross-section structure. During the flange punching process, the pressure tooth can apply downward pressure and lateral pressure to the blank. The downward pressure makes the blank press against the hollow punching die, and the lateral pressure helps to prevent the blank from displacement and deformation during the punching process, thereby improving the punching accuracy and the forming quality of the flange. In particular, when the inclined surface of the V-shaped pressure tooth generates lateral pressure when pressing the blank, the lateral pressure has a lateral component, forcing the material to gather toward the center and compensating for the thinning trend of the cylinder wall thickness during the stretching process. The uniform compressive stress distribution of the pressure tooth can suppress the lattice distortion of the punching area and reduce the influence of work hardening on subsequent stretching. Through the combined effect of the pressure force of the pressure tooth, the lower shear force of the hollow punching punch, the upper shear force of the hollow punching die, and the counter-top force of the hollow counter-top die, it is ensured that the blank remains stable during the punching process, thereby obtaining a high-quality shear surface.

[0014] A stretching height control member is provided in the hollow cavity of the hollow punching punch; when the stretching punch moves upward to stretch the boss into a cylinder, the stretching height control member limits the stretching height of the cylinder.

[0015] In this technical solution, in the process of the stretching punch stretching the boss into a cylinder, the stretching height control piece can limit the stretching height of the cylinder, ensure the consistency and accuracy of the cylinder height, improve the dimensional accuracy of the flexible wheel blank, and avoid material thinning or cracking due to excessive stretching. The mechanical limit function of the stretching height control piece not only controls the height of the cylinder, but also solves the problem of thin-wall stretching by forcing the material to extend evenly. Specifically, the cooperation of the stretching height control piece and the stretching punch forms an "axial constraint channel", which reduces the necking phenomenon caused by the difference in material flow rate by more than 80%. In addition, after the mechanical limit replaces the pure hydraulic control, the stress gradient at the end of the stretching is changed from the steep mutation of the traditional process (easy to cause cracking) to a smooth transition, which significantly reduces the cracking rate of the cylinder.

[0016] The lower die seat is provided with a plurality of flange hole punches, the hollow counter-top die is provided with avoidance holes corresponding one-to-one to the plurality of flange hole punches, the hollow punching punch is provided with a hole die corresponding one-to-one to the avoidance holes, an ejector rod is provided in the hole die, the flange hole punch moves into the hole die to punch flange holes on the flange, and the ejector rod is used to eject the waste material punched into the hole die.

[0017] In this technical solution, the lower die seat is provided with multiple flange hole punches, the hollow counter-top die and the hollow punching punch are respectively provided with corresponding avoidance holes and hole dies, and an ejector rod is provided in the hole dies. This structure can punch flange holes on the flange while punching the flange, and at the same time, the ejector rod can eject the waste material punched into the hole die, realizing the synchronous processing of the flange hole and the waste cleaning, and improving the production efficiency and product quality. In addition, the linkage design of the flange hole punch and the ejector rod, while achieving precise punching, brings dual benefits through timing optimization and self-cleaning mechanism: the flange hole punching and flange punching are carried out simultaneously, and the rigid state of the material during punching is used to avoid the hole position offset caused by step punching; the real-time waste removal function of the ejector rod greatly reduces the probability of scratching the mold surface, and with the precise guidance of the avoidance hole, the mold maintenance cycle is greatly extended.

[0018] The first die assembly includes a pre-stretching die, and the first punch assembly includes a pre-stretching punch. The pre-stretching die is provided with a pre-stretching cavity. The pre-stretching die and the pre-stretching punch enable the sheet to form a boss in the pre-stretching cavity. The boss includes a plane area in the middle and an arc area surrounding the plane area, and the cross-section of the arc area is S-shaped.

[0019] In this technical solution, the specific structure of the first die assembly and the first punch assembly is defined, and the pre-stretching die and the pre-stretching punch are used to form a boss of a specific structure on the sheet in the pre-stretching cavity, and the boss includes a plane area in the middle and a surrounding S-shaped arc surface area. The boss of this structure provides a good foundation for subsequent contour shaping and stretching processes, which is beneficial to improving the forming quality of the flexible wheel blank. The design of the S-shaped arc surface area breaks through the limitations of traditional plane transitions. The arc surface area acts as a "material buffer" in the pre-stretching stage, storing a certain amount of redundant material in the cylinder volume, providing supplements for subsequent stretching processes, and completely solving the problem of local tearing of thin-walled cylinders. At the same time, the S-shaped curvature greatly reduces the stress concentration factor, significantly delaying the initiation time of fatigue cracks of the flexible wheel under long-term alternating loads.

[0020] A first ejector member that can move up and down is provided in the middle of the pre-stretching die, and a first auxiliary oil cylinder and a first force transmission rod connecting the first auxiliary oil cylinder and the first ejector member are installed on the upper die seat, and the first auxiliary oil cylinder can drive the first ejector member to enter the pre-stretching cavity through the first force transmission rod.

[0021] In this technical solution, the design of the first ejector and the first auxiliary oil cylinder is introduced. The first ejector is driven by the first auxiliary oil cylinder to ensure the smooth forming and demolding of the sheet during the pre-stretching process. The first ejector driven by the first auxiliary oil cylinder is not only a demolding auxiliary device, but also realizes process optimization through dynamic pressure regulation. In the pre-stretching stage, the first ejector can exert a controllable reaction force to suppress the excessive thinning of the material in the plane area.

[0022] The second female die assembly includes a sizing female die, the second male die assembly includes a sizing male die, and the sizing female die is provided with a sizing cavity adapted to the contour of the sizing male die; the sizing female die and the sizing male die perform contour sizing on the boss in the sizing cavity, and the diameter of the flat area is increased and the slope of the arc area is increased through contour sizing.

[0023] In this technical solution, the specific structures of the second female die assembly and the second male die assembly are defined. The contour of the boss is sized in the sizing cavity by the sizing female die and the sizing male die, so that the diameter of the flat area is increased and the slope of the arc area is increased. This sizing operation can further optimize the shape of the boss, provide a more suitable shape for subsequent processes such as punching the center hole and stretching the cylinder body, and improve the forming accuracy of the flexspline blank. The contour sizing process realizes double process optimization by increasing the diameter of the flat area and the slope of the arc area: after the diameter of the flat area is expanded, a larger positioning reference surface is provided for subsequent punching, compressing the eccentricity error of the center hole; the increase in the slope of the arc area forms a "material diversion slope", effectively suppressing the generation of circumferential wrinkles and enabling the roundness of the cylinder body to reach a high-level accuracy.

[0024] A second ejector is provided in the middle of the sizing female die and can move up and down. The upper die holder is equipped with a second auxiliary oil cylinder and a second force transmission rod connecting the second auxiliary oil cylinder and the second ejector. The second auxiliary oil cylinder can drive the second ejector into the sizing cavity through the second force transmission rod.

[0025] In this technical solution, the design of the second ejector and the second auxiliary oil cylinder is introduced. The second ejector is driven by the second auxiliary oil cylinder to ensure the smooth demolding of the boss during the sizing process. Moreover, in the sizing process, the second auxiliary oil cylinder can slowly and evenly apply pressure to the boss to achieve buffering. The buffering effect reduces the peak value of the mold closing impact force, greatly reduces the propagation of microcracks on the cavity surface, and improves the mold life.

[0026] The third female die assembly includes a punching female die, the third male die assembly includes a punching male die, and the punching female die is provided with a punching cavity adapted to the boss after contour sizing; the punching female die and the punching male die punch a center hole in the boss in the punching cavity; a center punch is provided in the middle of the punching female die, a blanking hole is provided in the middle of the punching male die, and the center punch punches a center hole in the boss by moving into the blanking hole.

[0027] In this technical solution, the specific structures of the third female die assembly and the third male die assembly are defined. The center hole of the boss is punched in the punching cavity by the punching female die and the punching male die. The center punch in the middle of the punching female die and the blanking hole in the middle of the punching male die cooperate to accurately punch the center hole on the boss, preparing for the subsequent stretching cylinder process and improving the forming accuracy of the flexspline blank. The design of the blanking hole makes the punching waste in the shape of a regular cylinder, which is convenient for recycling (the recycling cost of traditional irregular waste is high).

[0028] Due to the adoption of the above technical solution, the technical effects achieved by this application are as follows: Through the different female die assemblies and male die assemblies sequentially arranged on the upper die base and the lower die base along the feeding direction, a series of operations such as pre-stretching of the sheet, profile shaping, punching of the center hole, blanking and stretching of the cylinder can be realized, gradually processing the sheet into a flexspline blank, forming a multi-station progressive die, integrating multiple stamping processes on a single die, enabling the flexspline blank to complete the forming of multiple features in one stamping stroke, reducing the handling and waiting time between processes, realizing the continuous production of the initial forming of the flexspline, improving production efficiency, reducing the material transfer and positioning error between processes, completing all processes within a single die, avoiding the tolerance stacking caused by multiple positionings, improving the coaxiality of the flexspline blank (the concentricity of the cylinder and the flange), and ensuring the accuracy and consistency of the flexspline blank. In the continuous processing of the progressive die, the cold work hardening effect of the sheet material is dispersed to each process, avoiding the increase in local brittleness caused by single severe deformation. This progressive die can minimize the waste of materials, make full use of the sheet material, reach a relatively high level of material utilization rate, and reduce production costs. Shearing and stretching are carried out simultaneously. The shearing force punches the flange, and the stretching force forms the cylinder. The multi-force sources act synergistically. The reverse shearing force and the stretching force offset part of the punching vibration, reduce die wear, and extend the service life, ensuring the dimensional accuracy and shape accuracy of the flexspline blank. The size deviation of the flexspline blank formed by stamping is small, the surface quality is good, and the subsequent machining allowance is small, which is beneficial to improving the quality and performance of the final product. Description of the Drawings

[0029] The drawings described herein are used to provide a further understanding of this application and form a part of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation of this application. In the drawings:

[0030] Figure 1 It is a schematic diagram of a multi-force source progressive die for the initial forming of a flexspline of a harmonic reducer provided by an embodiment of this application Figure 1 which shows the upper die base and the lower die base in the closed die state;

[0031] Figure 2 It is a schematic diagram of a multi-force source progressive die for the initial forming of a flexspline of a harmonic reducer provided by an embodiment of this application Figure 2, which shows the upper die base and the lower die base in a separated state;

[0032] Figure 3 This is a schematic diagram of the partial structure of the multi-force source continuous die for the initial forming of the harmonic reducer flexspline provided by the embodiment of the present application Figure 1 , which shows the upper die base and the lower die base in a closed die state;

[0033] Figure 4 This is a schematic diagram of the partial structure of the multi-force source continuous die for the initial forming of the harmonic reducer flexspline provided by the embodiment of the present application Figure 2 , which shows the multi-force source punch assembly and the multi-force source die assembly in a closed die state;

[0034] Figure 5 This is a schematic diagram of the sheet processing process provided by the embodiment of the present application Figure 1 ;

[0035] Figure 6 This is a schematic diagram of the sheet processing process provided by the embodiment of the present application Figure 2 .

[0036] List of components and reference numerals:

[0037] 1 Sheet, 11 Boss, 111 Flat area, 112 Arc area, 12 Center hole;

[0038] 2 Flexspline blank, 21 Cylinder, 22 Flange, 23 Flange hole;

[0039] 3 Upper die base, 31 Pre-stretching die, 311 Pre-stretching cavity, 312 First ejector, 32 Shaping die, 321 Shaping cavity, 322 Second ejector, 33 Punching die, 331 Punching cavity, 332 Center punch, 34 Hollow blanking punch, 341 Hole die, 342 Ejector rod, 343 Stretching height control part, 35 Blank holding teeth;

[0040] 4 Lower die base, 41 Pre-stretching punch, 42 Shaping punch, 43 Punching punch, 431 Blanking hole, 44 Hollow blanking die, 45 Hollow reverse ejector die, 451 Avoidance hole, 46 Stretching punch, 47 Flange hole punch;

[0041] 5 First auxiliary oil cylinder;

[0042] 6 First force transmission rod;

[0043] 7 Second auxiliary oil cylinder;

[0044] 8 Second force transmission rod. Detailed implementation manners

[0045] In order to more clearly explain the overall concept of the present application, the following will be described in detail by way of examples in combination with the drawings in the specification.

[0046] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present application is not limited by the specific embodiments disclosed below.

[0047] In addition, in the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", "lateral", "longitudinal", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0048] In the present application, unless otherwise clearly defined and limited, the terms "mounted", "connected", "connected to", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection, an electrical connection, or a communication connection; it may be directly connected, or indirectly connected through an intermediate medium, and may be the communication between two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0049] In the present application, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples.

[0050] The present application provides a multi-force-source progressive die for the initial forming of the flexspline of a harmonic reducer. For the convenience of description and understanding, the following content provided by the present application is all elaborated on the basis of the illustrated product structure. Of course, those skilled in the art can understand that the above structure is only a specific example and schematic illustration, and does not constitute a specific limitation to the technical solution provided by the present application.

[0051] Reference Figure 5 and Figure 6As shown in the figure, this embodiment relates to a multi-force-source progressive die for the initial forming of a harmonic reducer flexspline, which is used to process a sheet 1 into a flexspline blank 2. The flexspline blank 2 includes a cylinder body 21 and a flange 22. One end of the cylinder body 21 is connected to the flange 22 at the cylinder opening. In terms of the overall structure, as Figures 1 to 4 shown, the progressive die includes an upper die base 3 and a lower die base 4. A feeding channel is formed between the upper die base 3 and the lower die base 4. Along the feeding direction, the upper die base 3 is successively provided with a first concave die assembly, a second concave die assembly, a third concave die assembly, and a multi-force-source convex die assembly. Along the feeding direction, the lower die base 4 is successively provided with a first convex die assembly, a second convex die assembly, a third convex die assembly, and a multi-force-source concave die assembly.

[0052] As Figure 2 shown, it is the state where the upper die base 3 and the lower die base 4 are separated. As Figure 1 and Figure 3 shown, it is the state where the upper die base 3 and the lower die base 4 are closed. When the upper die base 3 and the lower die base 4 are closed, the first concave die assembly and the first convex die assembly pre-stretch the sheet 1 to form a boss 11. The second concave die assembly and the second convex die assembly perform profile shaping on the pre-stretched boss 11. The third concave die assembly and the third convex die assembly punch a center hole 12 on the boss 11 after profile shaping. The multi-force-source convex die assembly and the multi-force-source concave die assembly apply mutually reverse shear forces and tensile forces to the sheet 1 with the center hole 12 punched. The flange 22 is blanked out by the shear force to achieve blanking, and the boss 11 with the center hole 12 is stretched into the cylinder body 21 by the tensile force.

[0053] Based on the above overall introduction, as Figure 5 and Figure 6 shown, it is the structural change of the sheet 1 in each process during the processing of the progressive die, and finally the formed flexspline blank 2 is blanked out. The separation and closing power of the upper die base 3 and the lower die base 4, the stamping power of the first concave die assembly and the first convex die assembly, the stamping power of the second concave die assembly and the second convex die assembly, the stamping power of the third concave die assembly and the third convex die assembly, and the stamping power of the multi-force-source convex die assembly and the multi-force-source concave die assembly can all be provided by a hydraulic mechanism.

[0054] Regarding the structures of the first concave die assembly and the first convex die assembly, in a preferred embodiment, as Figures 1 to 3As shown, the first die assembly includes a pre-stretching die 31, the first punch assembly includes a pre-stretching punch 41, the pre-stretching die 31 is provided with a pre-stretching cavity 311, and when the pre-stretching punch 41 and the pre-stretching die 31 are molded together, the two are stamped to form a boss 11. As a preferred embodiment, a first ejector 312 that can move up and down is provided in the middle of the pre-stretching die 31, and the upper die base 3 is equipped with a first auxiliary oil cylinder 5 and a first force transmission rod 6 connecting the first auxiliary oil cylinder 5 and the first ejector 312, and the first auxiliary oil cylinder 5 can drive the first ejector 312 to enter the pre-stretching cavity 311 through the first force transmission rod 6. This solution introduces the design of the first ejector 312 and the first auxiliary oil cylinder 5. The first ejector 312 is driven by the first auxiliary oil cylinder 5 to ensure the smooth forming and demolding of the sheet 1 during the pre-stretching process. Specifically, in the process of the pre-stretching punch 41 and the pre-stretching die 31 being combined to stamp out the boss 11, the first auxiliary oil cylinder 5 applies pressure to the first ejector 312 to maintain the flatness of the inner contour of the pre-stretching die 31. After the stamping of the boss 11 is completed, when the pre-stretching punch 41 is separated from the pre-stretching die 31, the first ejector 312 can be further extended into the pre-stretching cavity 311 by the first auxiliary oil cylinder 5 to ensure that the boss 11 is smoothly separated from the pre-stretching die 31. The first ejector 312 driven by the first auxiliary oil cylinder 5 is not only a demolding auxiliary device, but also realizes process optimization through dynamic pressure regulation. In the pre-stretching stage, the first ejector 312 can apply a controllable reaction force to suppress the excessive thinning of the material in the plane area 111.

[0055] Regarding the structure of the second concave mold component and the second convex mold component, in a preferred embodiment, as Figures 1 to 3As shown, the second female die assembly includes a sizing female die 32, and the second male die assembly includes a sizing male die 42. The sizing female die 32 is provided with a sizing cavity 321 adapted to the contour of the sizing male die 42. When the sizing female die 32 and the sizing male die 42 are closed, the two perform stamping to size the boss 11. As a preferred embodiment, a second ejector 322 that can move up and down is provided in the middle of the sizing female die 32. The upper die base 3 is provided with a second auxiliary oil cylinder 7 and a second force transmission rod 8 connecting the second auxiliary oil cylinder 7 and the second ejector 322. The second auxiliary oil cylinder 7 can drive the second ejector 322 into the sizing cavity 321 through the second force transmission rod 8. In this technical solution, the design of the second ejector 322 and the second auxiliary oil cylinder 7 is introduced. The second auxiliary oil cylinder 7 drives the second ejector 322 to ensure the smooth demolding of the boss 11 during the sizing process. Specifically, during the process of the sizing male die 42 and the sizing female die 32 closing to size the boss 11, the second auxiliary oil cylinder 7 applies pressure to the second ejector 322 to maintain the flatness of the inner contour of the sizing female die 32. After the sizing of the boss 11 is completed, when the sizing male die 42 and the sizing female die 32 are separated, the second auxiliary oil cylinder 7 can further extend the second ejector 322 into the sizing cavity 321 to ensure that the boss 11 smoothly detaches from the sizing female die 32. Moreover, in the sizing process, the second auxiliary oil cylinder 7 can slowly and evenly apply pressure to the boss 11 to achieve buffering. The buffering effect reduces the peak value of the mold closing impact force, greatly reduces the propagation of microcracks on the cavity surface, and improves the mold life.

[0056] Regarding the structures of the third female die assembly and the third male die assembly, in a preferred embodiment, as Figures 1 to 3 shown, the third female die assembly includes a punching female die 33, and the third male die assembly includes a punching male die 43. The punching female die 33 is provided with a punching cavity 331 adapted to the boss 11 after contour sizing; the punching female die 33 and the punching male die are used to punch a central hole 12 in the boss 11 within the punching cavity 331; a center punch 332 is provided in the middle of the punching female die 33, and a blanking hole 431 is provided in the middle of the punching male die 43. The center punch 332 punches a central hole 12 in the boss 11 by moving into the blanking hole 431. The wall contour of the punching cavity 331 is consistent with the contour of the boss 11 after sizing. When the punching female die 33 and the punching male die 43 are closed, the boss 11 is clamped, and then the center punch 332 extends into the blanking hole 431 to punch a central hole 12 in the boss 11, and the waste enters the blanking hole 431 or is discharged through the blanking hole 431 to the waste collection area.

[0057] Regarding the structures of the multi-force source male die assembly and the multi-force source female die assembly, in a preferred embodiment, as Figures 1 to 4As shown, the multi-force source punch assembly includes a hollow blanking punch 34. The multi-force source die assembly includes a hollow blanking die 44, a hollow reverse punching die 45, and a stretching punch 46 that are nested in sequence from outside to inside. The hollow blanking punch 34, the hollow blanking die 44, and the hollow reverse punching die 45 cooperate to punch a flange 22 on the sheet 1, and the stretching punch 46 cooperates with the hollow blanking punch 34 to stretch the boss 11 into a thin-walled cylinder 21.

[0058] In a preferred embodiment, as Figure 4 shown, the upper die holder 3 is provided with a blank holding tooth 35 surrounding the hollow blanking punch 34, and the blank holding tooth 35 is set to have a V-shaped cross-section structure.

[0059] In a preferred embodiment, as Figure 3 and Figure 4 shown, a stretching height control member 343 is provided in the hollow cavity of the hollow blanking punch 34; during the process of the stretching punch 46 moving upward to stretch the boss 11 into a cylinder 21, the stretching height control member 343 limits the stretching height of the cylinder 21. In this technical solution, during the process of the stretching punch 46 stretching the boss 11 into a cylinder 21, the stretching height control member 343 can limit the stretching height of the cylinder 21, ensure the consistency and accuracy of the height of the cylinder 21, improve the dimensional accuracy of the flexspline blank 2, and avoid thinning or cracking of the material caused by excessive stretching. The mechanical limit function of the stretching height control member 343 not only controls the height of the cylinder 21, but also solves the problem of thin-wall stretching by forcing the material to extend uniformly. Specifically, the cooperation between the stretching height control member 343 and the stretching punch 46 forms an "axial constraint channel", reducing the necking phenomenon caused by the difference in material flow rate by more than 80%. In addition, after the mechanical limit replaces the pure hydraulic control, the stress gradient at the end of stretching changes from a steep mutation (prone to cracking) in the traditional process to a smooth transition, significantly reducing the cracking rate of the cylinder 21.

[0060] In a preferred embodiment, as Figure 3 and Figure 4As shown, the lower die base 4 is provided with a plurality of flange hole punches 47, the hollow reverse top die 45 is provided with avoidance holes 451 corresponding to the plurality of flange hole punches 47, the hollow punching punch 34 is provided with a hole die 341 corresponding to the avoidance holes 451, and an ejector rod 342 is provided in the hole die 341. The flange hole punch 47 moves into the hole die 341 to punch the flange hole 23 on the flange 22, and the ejector rod 342 is used to eject the waste material punched into the hole die 341. In the technical solution, the lower die base 4 is provided with a plurality of flange hole punches 47, the hollow reverse top die 45 and the hollow punching punch 34 are provided with corresponding avoidance holes 451 and hole die 341, respectively, and an ejector rod 342 is provided in the hole die 341. This structure can punch the flange hole 23 on the flange 22 while punching the flange 22, and the ejector rod 342 can eject the waste material punched into the hole die 341, realizing the synchronous processing of the flange hole 23 and the waste material cleaning, thereby improving production efficiency and product quality. In addition, the linkage design of the flange hole punch 47 and the ejector rod 342, while achieving precise punching, brings dual benefits through timing optimization and self-cleaning mechanism: the punching of the flange hole 23 is carried out simultaneously with the punching of the flange 22, and the rigid state of the material during punching is used to avoid the hole position offset caused by step punching; the real-time waste material cleaning function of the ejector rod 342 greatly reduces the probability of scratching the mold surface, and with the precise guidance of the avoidance hole 451, the mold maintenance cycle is greatly extended.

[0061] The following is the processing technology of the continuous die. In the process of continuously conveying the sheet 1, the upper die base 3 and the lower die base 4 can use hydraulic power to synchronously realize five processing steps, namely, pre-stretching process, contour shaping process, punching process, multi-force source blanking and stretching process, and flange hole punching process.

[0062] Pre-stretching process: the pre-stretching die 31 cooperates with the pre-stretching punch 41, and the first auxiliary oil cylinder 5 applies pressure to the first ejector 312 to maintain the flatness of the inner contour of the pre-stretching die 31, so that the sheet 1 forms a boss 11 with a flat area 111 and a curved area 112 in the pre-stretching cavity 311. Figure 5 and Figure 6 As shown, the boss 11 includes a plane area 111 located in the middle and a curved area 112 surrounding the plane area 111. The cross section of the curved area 112 is S-shaped. At this time, the curved area 112 is in a relatively flat state. It acts as a "material buffer" in the pre-stretching stage, storing a certain amount of redundant material of the cylinder 21, providing a supplement for the subsequent stretching process, and completely solving the problem of local tearing of the thin-walled cylinder 21. At the same time, the S-shaped curvature greatly reduces the stress concentration factor, significantly delaying the fatigue crack initiation time of the flexible wheel under long-term alternating loads. When the pre-stretching punch 41 is separated from the pre-stretching die 31, the first auxiliary cylinder 5 extends the first ejector 312 further into the pre-stretching cavity 311 to ensure smooth demolding of the boss 11.

[0063] Contour shaping process: The shaping die 32 cooperates with the shaping punch 42, and the second auxiliary oil cylinder 7 applies pressure to the second ejector 322 to maintain the flatness of the inner contour of the shaping die 32, so that the boss 11 is contoured in the shaping cavity 321. The diameter of the plane area 111 is increased and the slope of the arc area 112 is increased through contour shaping. The arc area 112 changes from a relatively gentle state to a relatively steep state, and can be extended to have rounded corners at both ends, and the rounded corners at both ends transition through the middle vertical surface. After the diameter of the plane area 111 is expanded, a larger positioning reference surface is provided for subsequent punching, so that the eccentricity error of the center hole 12 is compressed; the increase in the slope of the arc area 112 forms a "material diversion slope", which effectively suppresses the generation of circumferential wrinkles and makes the roundness of the cylinder 21 reach a high level of accuracy. When the shaping convex mold 42 is separated from the shaping concave mold 32 , the second auxiliary oil cylinder 7 extends the second ejector 322 further into the shaping cavity 321 to ensure that the boss 11 is smoothly demoulded.

[0064] Punching process: the punching die 33 and the punching punch 43 cooperate to clamp the boss 11, and the center punch 332 in the middle of the punching die 33 moves into the lower material hole 431 to punch the center hole 12 on the boss 11 after contour shaping. When the punching die 33 and the punch 43 are separated, the center punch 332 is reset.

[0065] Multi-source punching and stretching process: Figure 4 As shown, the hollow punching punch 34 applies a lower shear force F1 to the sheet 1, the hollow punching die 44 applies an upper shear force F2 to the sheet 1, the edge pressing teeth 35 press into the surface of the sheet 1, apply a lower pressure F3 and a side pressure F4, the hollow counter-top die 45 applies a counter-top force F5 to the sheet 1 and moves down synchronously with the hollow punching punch 34, punching out the flange 22 to achieve blanking. At the same time, the stretching punch 46 moves upward into the hollow cavity of the hollow punching punch 34 and passes through the center hole 12 of the boss 11, and together with the hollow punching punch 34, stretches the boss 11 with the center hole 12 into the cylinder 21, and the stretching height control member 343 limits the stretching height of the cylinder 21.

[0066] Flange hole punching process: the flange hole punch 47 of the lower die seat 4 moves into the hole die 341 to punch the flange hole on the flange 22, and the ejector rod 342 ejects the waste material punched into the hole die 341 to avoid waste material accumulation.

[0067] Anything not described in this application can be achieved by adopting or drawing on existing technologies.

[0068] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0069] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the scope of the claims of the present application.

Claims

1. A multi-force source continuous die for the initial forming of a harmonic reducer flexspline, used for processing a sheet into a flexspline blank, the flexspline blank comprising a cylinder and a flange, one end of the cylinder being connected to the flange at its mouth, characterized in that: The continuous die comprises an upper die base and a lower die base, a feeding channel is formed between the upper die base and the lower die base, the upper die base is provided with a first die assembly, a second die assembly, a third die assembly and a multi-force source punch assembly in sequence along the feeding direction, and the lower die base is provided with a first punch assembly, a second punch assembly, a third punch assembly and a multi-force source die assembly in sequence along the feeding direction; When the upper die base and the lower die base are closed, the first die assembly and the first punch assembly pre-stretch the sheet to form a boss, the second die assembly and the second punch assembly perform contour shaping on the pre-stretched boss, the third die assembly and the third punch assembly punch a center hole on the boss after contour shaping, the multi-force source punch assembly and the multi-force source die assembly apply opposite shearing force and tensile force to the sheet that has passed through the punched center hole, the flange is punched out by the shear force to achieve material cutting, and the boss with the center hole is stretched into a cylinder by the tensile force.

2. The multi-force source continuous die for the primary forming of the harmonic reducer flexible wheel according to claim 1 is characterized in that: The multi-force source punch assembly includes a hollow punch, and the multi-force source die assembly includes a hollow punch die, a hollow top die and a stretching punch which are nested in sequence from outside to inside; When the hollow punching punch and the hollow punching die are closed, the hollow punching punch applies a downward shear force to the sheet, the hollow punching die applies an upward shear force to the sheet, the hollow counter-top die applies an upward counter-top force to the sheet and moves downward synchronously with the hollow punching punch to punch out a flange by the upper shear force, the lower shear force and the counter-top force, the stretching punch moves upward into the hollow cavity of the hollow punching punch and passes through the center hole to stretch the boss into a cylinder together with the hollow punching punch.

3. The multi-force source continuous die for the primary forming of the harmonic reducer flexible wheel according to claim 2 is characterized in that: The upper die seat is provided with a pressing tooth surrounding the hollow punching punch, and the pressing tooth is arranged to have a V-shaped cross-section. During the process of punching out the flange by the hollow punching punch and the hollow punching die, the pressing tooth is pressed into the surface of the sheet to apply a downward pressure to the sheet against the hollow punching die, and to apply a side pressure to the sheet that has an angle with the downward pressure.

4. The multi-force source continuous die for the primary forming of the harmonic reducer flexspline according to claim 2 is characterized in that: A stretching height control member is provided in the hollow cavity of the hollow punching punch; when the stretching punch moves upward to stretch the boss into a cylinder, the stretching height control member limits the stretching height of the cylinder.

5. The harmonic reducer flexible wheel primary forming multi-force source continuous die according to claim 2, characterized in that: The lower die seat is provided with a plurality of flange hole punches, the hollow counter-top die is provided with avoidance holes corresponding one-to-one to the plurality of flange hole punches, the hollow punching punch is provided with a hole die corresponding one-to-one to the avoidance holes, an ejector rod is provided in the hole die, the flange hole punch moves into the hole die to punch flange holes on the flange, and the ejector rod is used to eject the waste material punched into the hole die.

6. The multi-force source continuous die for the primary forming of the harmonic reducer flexible wheel according to claim 1, characterized in that: The first die assembly includes a pre-stretching die, and the first punch assembly includes a pre-stretching punch. The pre-stretching die is provided with a pre-stretching cavity. The pre-stretching die and the pre-stretching punch enable the sheet to form a boss in the pre-stretching cavity. The boss includes a plane area in the middle and an arc area surrounding the plane area, and the cross-section of the arc area is S-shaped.

7. The multi-force source continuous die for the primary forming of the harmonic reducer flexspline according to claim 6 is characterized in that: A first ejector member that can move up and down is provided in the middle of the pre-stretching die, and a first auxiliary oil cylinder and a first force transmission rod connecting the first auxiliary oil cylinder and the first ejector member are installed on the upper die seat, and the first auxiliary oil cylinder can drive the first ejector member to enter the pre-stretching cavity through the first force transmission rod.

8. The multi-force source continuous die for the primary forming of the harmonic reducer flexspline according to claim 6, characterized in that: The second die assembly includes a shaping die, and the second punch assembly includes a shaping punch. The shaping die is provided with a shaping cavity adapted to the contour of the shaping punch. The shaping die and the shaping punch shape the contour of the boss in the shaping cavity, and the diameter of the plane area is increased and the slope of the arc area is increased through contour shaping.

9. The multi-force source continuous die for the primary forming of the harmonic reducer flexible wheel according to claim 8, characterized in that: A second ejector that can move up and down is provided in the middle of the shaping die, and a second auxiliary oil cylinder and a second force transmission rod connecting the second auxiliary oil cylinder and the second ejector are installed on the upper die seat, and the second auxiliary oil cylinder can drive the second ejector to enter the shaping cavity through the second force transmission rod.

10. The multi-force source continuous die for the primary forming of the harmonic reducer flexspline according to claim 1, characterized in that: The third die assembly includes a punching die, and the third punch assembly includes a punching punch. The punching die is provided with a punching cavity adapted to fit the boss after contour shaping; the punching die and the punching convex enable the boss to punch a center hole in the punching cavity; a center punch is provided in the middle of the punching die, and a blanking hole is provided in the middle of the punching punch, and the center punch punches a center hole on the boss by moving into the blanking hole.

Images