A multi-spinning-point loading low-stress feeding device and method

Abstract

This invention provides a multi-rotation-point loading low-stress blanking device and method, belonging to the field of low-stress blanking technology. The device includes a frame, a loading mechanism, a clamping and rotating mechanism, and a rotation point switching mechanism. The loading mechanism, clamping and rotating mechanism, and rotation point switching mechanism are all mounted on the frame. The loading mechanism and rotation point switching mechanism are respectively located on the left and right sides of the clamping and rotating mechanism. The loading mechanism provides a loading force to the bar stock, causing it to bend and deflect. The loading mechanism is electrically connected to the control system. The method includes: bar stock pretreatment, bar stock installation, preset loading force, and blanking. This invention can ensure uniform radial depth expansion during the circumferential length extension of the crack in the bar stock during low-stress blanking, solving the problem of a large and eccentric instantaneous fracture zone area during bar stock blanking.

Description

Technical Field

[0001] This invention belongs to the field of low-stress material preparation technology, and specifically relates to a multi-rotation point loading low-stress material preparation device and method. Background Technology

[0002] Low-stress blanking applies crack technology to bar blanking. A circumferential crack is artificially created on the surface of the bar. Then, an external force is applied to the bar with the circumferential surface crack, causing stress concentration to propagate the crack perpendicular to the axis at a specific location, resulting in dynamic separation of the bar through low-stress brittle fracture. Currently, scholars have conducted some research on low-stress blanking technology from the aspects of stress concentration, mechanism design, and fracture morphology. However, key core technologies such as the material separation mechanism, efficient and precise implementation methods, and quality evaluation standards for low-stress blanking have not yet been mastered. Therefore, the comprehensive goals of improving product precision and production efficiency, reducing energy consumption, and reducing pollution have not been truly achieved. To accelerate the development of my country's equipment manufacturing industry, it is imperative to research new near-net-shape forming blanking technologies and material separation mechanisms for efficient, high-quality, energy-saving, and environmentally friendly metallic materials.

[0003] Existing low-stress blanking technology is generally the rotary bending low-stress blanking technology, as shown in Figure 12. The rotary bending low-stress blanking machine based on hydraulic compensation mainly consists of six parts: a variable frequency motor 1, a hydraulic transmission system 2, a double slider mechanism 3, a blanking die 4, a movable clamping mechanism 5, and a blanking frame 6. Among them, the blanking die 4 is the main force-bearing component of the blanking machine, which largely determines the performance and lifespan of the blanking machine. It mainly includes a shaft head 7, a slider 8, and a bearing 9. During blanking, the bar stock is first pre-grooved with a ring-shaped V-groove. Then, one end of the bar stock with the V-groove is placed into the bearing 9 in the blanking die 4, and the other end is fixed in the movable clamping mechanism 5. The variable frequency motor 1 drives the blanking die 4 to rotate. Due to the high speed of the blanking machine's main shaft, its small mass and rotation radius generate a large centrifugal force, which acts on the bar stock through the bearing 9, thereby causing cracks at the tip of the V-groove of the bar stock. By controlling the loading force, the crack at the tip of the V-groove initiates and rapidly propagates radially, eventually fracturing completely and achieving blanking. However, because the blanking die continuously applies loading force to the bar stock, it is impossible to change the loading force in real time, making it difficult to control the crack initiation and propagation direction. This results in severe eccentricity of the blanked section, poor flatness, and consequently, poor quality. Furthermore, due to the continuous loading of the blanking die, the die is in constant contact with the metal bar stock, applying radial pressure during rotation at a relatively high speed, making it impossible to adjust the loading force at various circumferential positions. When a crack occurs at a certain circumferential position on the bottom of the groove in the metal bar stock, the concentration effect at that location intensifies, making it more prone to further cracking. Since the loading force of the die is consistent across all circumferential positions, the crack depth at this location will be greater than at other circumferential positions, creating a vicious cycle: the greater the crack depth, the easier it is for further cracking, ultimately leading to an eccentric and large instantaneous fracture zone.

[0004] Current research on crack propagation during low-stress loading is limited to crack initiation and crack depth propagation. While this helps analyze the changes in loading force caused by depth variations during low-stress loading and can guide loading curves at several nodes, these studies neglect the circumferential crack length propagation process. The uneven radial depth propagation that occurs during this process is the fundamental reason for the large and eccentric area of ​​the instantaneous fracture zone.

[0005] Therefore, the problem of a large and eccentric instantaneous fracture zone in bar stock can only be solved by ensuring uniform radial depth expansion during the circumferential length extension of the crack in the bar stock during low-stress cutting. Summary of the Invention

[0006] In view of this, the present invention provides a multi-rotation point loading low-stress feeding device and method, which can ensure that the radial depth of the bar stock is uniformly expanded when the circumferential length of the crack expands during the low-stress feeding process, and solve the problem of large area and eccentricity of the instantaneous fracture zone during bar stock feeding.

[0007] This invention is implemented as follows:

[0008] In a first aspect, the present invention provides a multi-rotation point loading low-stress feeding device, comprising a frame, a loading mechanism, a clamping rotation mechanism, and a rotation point switching mechanism. The loading mechanism, the clamping rotation mechanism, and the rotation point switching mechanism are all mounted on the frame, and the loading mechanism and the rotation point switching mechanism are respectively disposed on the left and right sides of the clamping rotation mechanism.

[0009] Based on the above technical solution, the multi-rotation point loading low-stress feeding device of the present invention can be further improved as follows:

[0010] The clamping and rotating mechanism includes a servo motor, a three-jaw chuck, and a power shaft. The servo motor is installed at the bottom of the frame, and the power shaft and the three-jaw chuck are installed on the top surface of the frame. The three-jaw chuck is fixedly connected to one end of the power shaft and is coaxial with the power shaft. The servo motor is driven by the power shaft.

[0011] The rotary switch mechanism comprises a rotary switch, a grooved wheel bracket, and a dial; the rotary switch includes a grooved wheel and a grooved wheel shaft, the grooved wheel is sleeved on the front end of the grooved wheel shaft and rotatably connected to the grooved wheel shaft; the grooved wheel has cylindrical pin slots evenly distributed radially, and grooved wheel contacts are evenly distributed circumferentially along the inner diameter of the grooved wheel; contact switches are evenly distributed circumferentially along the outer diameter of the grooved wheel shaft, and the contact switches can be triggered by the grooved wheel contacts to open the loading mechanism; the contact switches, the servo motor, and the control system are electrically connected.

[0012] The right end face of the grooved wheel bracket is flush with the right end face of the power shaft and fixed on the frame. The grooved wheel bracket has a through hole in the middle that is concentric with the power shaft. The inner diameter of the through hole has continuously and evenly distributed through hole teeth. The right end of the power shaft is fitted with the dial. The outer diameter of the dial has continuously and evenly distributed spindle teeth. The spindle teeth correspond one-to-one with the through hole teeth, forming a gap in the middle to fix the grooved wheel shaft. Multiple rotary switches are installed in the dial and the grooved wheel bracket. The dial also has a cylindrical pin that can be inserted into the cylindrical pin slot.

[0013] The loading mechanism is used to provide loading force to the bar stock, causing the bar stock to bend and generate deflection. The loading mechanism is electrically connected to the control system.

[0014] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: by setting up a loading mechanism controlled by a rotary switch mechanism, the low stress applied to the bar stock is intermittent rather than continuous, thereby realizing the intermittent change of the loading stress and avoiding the difficulty in controlling the cracks in the bar stock, which would lead to the eccentricity of the blanking section and reduce the blanking quality.

[0015] Furthermore, a control interface is also installed on the frame, and the control interface is electrically connected to the control system; the control interface facilitates the setting of parameters for the loading mechanism.

[0016] Furthermore, a drive gear is fixed on the power output end of the servo motor, a driven gear is sleeved on the power shaft, the drive gear and the driven gear are connected by a synchronous belt, and the three-jaw chuck is located at the end of the power shaft away from the synchronous belt.

[0017] The beneficial effects of adopting the above-mentioned improved scheme are as follows: driving the power shaft to rotate via belt transmission has the advantages of high transmission efficiency, good load capacity, and long service life; changing the rotation of the blanking die to the rotation of the bar stock makes the loading force easier to control.

[0018] Furthermore, the frame is provided with an adjusting slide rail, and a main shaft sleeve block for fixing the power shaft is sleeved on the outside of the power shaft. The bottom of the main shaft sleeve block and the grooved wheel bracket are slidably connected to the adjusting slide rail through an adjusting slider.

[0019] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: by setting the adjustment slide rail and the adjustment slider, the position of the clamping rotation mechanism and the rotary switch mechanism on the frame can be adjusted, which can ensure that the adjusted clamping rotation mechanism and the rotary switch mechanism are kept on the same horizontal line, and facilitate the adjustment of the extension length of the cantilever end of the bar stock.

[0020] Furthermore, one of the adjusting sliders is simultaneously fixed to the bottom of both the power shaft and the main shaft sleeve.

[0021] The beneficial effects of adopting the above-mentioned improved scheme are: by setting the clamping and rotating mechanism and the rotary switch mechanism as described above, they can move synchronously, saving adjustment time.

[0022] Furthermore, the servo motor is suspended at the bottom of the frame via a sliding rod mechanism. The sliding rod mechanism includes an adjusting slide rod and a motor fixing plate. The motor fixing plate is fixedly connected to the servo motor. The adjusting slide rod is fixed to one end of the upper surface of the frame near the grooved wheel bracket via a slide rod sleeve block. The adjusting slide rod and the slide rod sleeve block are threadedly rotatably connected. The upper end of the motor fixing plate is fixedly connected to the adjusting slide rod.

[0023] The beneficial effects of adopting the above-mentioned improvement scheme are: by setting a sliding rod mechanism, it is convenient to adjust the relative position of the servo motor when adjusting the position of the three-jaw chuck and the power shaft.

[0024] Furthermore, the loading mechanism includes guide columns, a hydraulic telescopic cylinder, and a loading assembly. Two sets of guide columns are symmetrically distributed on both sides of the power shaft. The bottom of each guide column is fixedly connected to the top of the frame. A connecting plate is slidably connected between the two guide columns, and a fixing plate is fixedly connected between the tops of the two guide columns. The bottom of the connecting plate is fixedly connected to the loading assembly, and the fixing plate is fixedly connected to the hydraulic telescopic cylinder. The telescopic end of the hydraulic telescopic cylinder is fixedly connected to the top of the connecting plate. The hydraulic pipe of the hydraulic telescopic cylinder is connected to an oil tank at the bottom of the frame, and the hydraulic telescopic cylinder is electrically connected to the control system.

[0025] Furthermore, each of the aforementioned contact switches corresponds to activating a different extension / retraction length of the hydraulic telescopic cylinder.

[0026] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the optimal and reasonable loading force and loading position are different for bars with different materials and parameters. Therefore, by setting the starting parameters of the hydraulic telescopic cylinder, the loading effect of the hydraulic telescopic cylinder on the bars can be improved.

[0027] Furthermore, each of the grooved wheels has three of the cylindrical pin slots.

[0028] Secondly, the present invention provides a method for low-stress material preparation using multi-spinning-point loading, applied to the aforementioned multi-spinning-point loading low-stress material preparation device, comprising the following steps:

[0029] S1: Bar stock pretreatment, machining V-grooves at the pre-fracture position of the bar stock, and determining the effective loading position of the bar stock, i.e., the rotation point position;

[0030] S2: Install bar stock. Pass the bar stock to be unloaded through the loading component, then pass the bar stock through the three-jaw chuck and clamp and fix the bar stock with the three-jaw chuck. Install the rotary switch at the position of the rotary switch mechanism corresponding to the rotary point of the bar stock.

[0031] S3: Preset loading force, the control system sets different extension lengths of the hydraulic telescopic cylinder corresponding to each grooved wheel shaft, that is, the hydraulic telescopic cylinder applies different loading forces to the bar stock;

[0032] S4: Material unloading is performed. The power of the servo motor is output to the synchronous belt, which drives the bar held on the three-jaw chuck to rotate. The cylindrical pin on the dial engages with the cylindrical pin slot on the grooved wheel of the rotary switch, thereby driving the grooved wheel to rotate on the grooved wheel shaft. The grooved wheel contact triggers the contact switch, activating the hydraulic telescopic cylinder to extend and retract the bar with a corresponding loading force. The cylindrical pin on the dial continuously engages with the next rotary switch, causing the hydraulic telescopic cylinder to intermittently start to load the bar with different forces until a crack appears at the bottom of the V-groove of the bar. The crack then continuously expands circumferentially, completing one unloading operation.

[0033] Compared with the prior art, the beneficial effects of the multi-spinning-point loading low-stress feeding device and method provided by the present invention are:

[0034] 1. It can realize a multi-spinning point loading low-stress cutting method, which applies discontinuous loading with different loading forces at appropriate positions in the circumference of the bar stock, so as to achieve accurate application of loading force during the cutting process and obtain ideal extended cracks.

[0035] 2. By setting a rotary switch mechanism, the continuous rotation of the bar stock is linked with the discontinuous loading of the loading mechanism. The intermittent motion mechanism of the loading mechanism can accurately control the number and position of rotary switches on the bar stock surface by changing the number and position of the rotary switches installed on the grooved wheel bracket. By setting the rotary loading force corresponding to different rotary switches, the loading force at a set position in the circumference of the bar stock can be varied, achieving precise low-stress loading. This enables discontinuous application of loading force, accurately controls the crack propagation path and length, and obtains a high-quality blanking cross-section.

[0036] 3. By setting up a loading mechanism, the rotation of the bar stock at the corresponding position of the rotation point is converted into the linear reciprocating motion of the loading mold, so as to realize accurate and intuitive control of multi-rotation point loading and unloading, and to accurately load the loading force and loading position required for unloading under theoretical research, thereby improving unloading efficiency and reducing wear on the surface of the bar stock. Attached Figure Description

[0037] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of a multi-spinning-point loading low-stress feeding machine device provided by the present invention;

[0039] Figure 2This is a schematic diagram of the clamping and rotating mechanism in a multi-rotation point loading low-stress feeding device provided by the present invention;

[0040] Figure 3 for Figure 2 Enlarged view of section A;

[0041] Figure 4 This invention provides a schematic diagram of a rotary point switch in a multi-rotation point loading low-stress feeding device;

[0042] Figure 5 This invention provides a schematic diagram of the loading mechanism in a multi-rotation point loading low-stress feeding device;

[0043] Figure 6 This invention provides an electrical connection diagram for a multi-spinning-point loading low-stress feeding device;

[0044] Figure 7 This invention provides a flowchart of a method for low-stress blanking with multi-spinning point loading;

[0045] Figure 8 The background diagram shows the bar stock processing of a low-stress blanking machine.

[0046] Figure 9 This invention provides a working principle diagram of a multi-rotation point loading low-stress feeding device;

[0047] Figure 10 A diagram illustrating the crack propagation morphology of a bar stock is provided to illustrate the working principle of a multi-spinning-point loading low-stress feeding device according to the present invention.

[0048] Figure 11 This is a curve showing the displacement load-loading sequence.

[0049] The attached diagram lists the components represented by each number as follows:

[0050] 01. Loading mechanism; 011. Guide column; 0111. Connecting plate; 0112. Fixing plate; 012. Hydraulic telescopic cylinder; 0121. Oil tank; 013. Loading assembly; 02. Clamping and rotating mechanism; 021. Servo motor; 0211. Drive gear; 022. Three-jaw chuck; 023. Synchronous belt; 024. Drive shaft; 0241. Driven gear; 03. Rotary switch mechanism; 031. Rotary switch; 0311. Geneva wheel; 03110. Geneva wheel contact; 03111. Cylindrical pin Bayonet; 0312, Grooved wheel shaft; 03120, Contact switch; 032, Grooved wheel bracket; 033, Dial; 0331, Cylindrical pin; 04, Control operation interface; 05, Frame; 051, Adjusting slide rail; 052, Adjusting slider; 081, Adjusting slide rod; 082, Motor fixing plate; 1, Variable frequency motor; 2, Hydraulic transmission system; 20, Control system; 3, Double slider mechanism; 4, Unloading mold; 5, Movable clamping mechanism; 6, Unloading frame; 7, Shaft head; 8, Slider; 9, Bearing. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0053] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0054] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0055] Furthermore, in the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0056] like Figure 1 As shown, a multi-rotation point loading low-stress feeding device provided by the first aspect of the present invention includes a frame 05, a loading mechanism 01, a clamping rotation mechanism 02 and a rotation point switching mechanism 03. The loading mechanism 01, the clamping rotation mechanism 02 and the rotation point switching mechanism 03 are all mounted on the frame 05. The loading mechanism 01 and the rotation point switching mechanism 03 are respectively arranged on the left and right sides of the clamping rotation mechanism 02.

[0057] like Figure 2-4 As shown, in the above technical solution,

[0058] The clamping and rotating mechanism 02 includes a servo motor 021, a three-jaw chuck 022, and a power shaft 024. The servo motor 021 is installed at the bottom of the frame 05, and the power shaft 024 and the three-jaw chuck 022 are installed on the top surface of the frame 05. The three-jaw chuck 022 is fixedly connected to one end of the power shaft 024 and is coaxial with the power shaft 024. The servo motor 021 is connected to the power shaft 024 for transmission.

[0059] The rotary switch mechanism 03 comprises a rotary switch 031, a grooved wheel bracket 032, and a dial 033. The rotary switch 031 includes a grooved wheel 0311 and a grooved wheel shaft 0312. The grooved wheel 0311 is sleeved on the front end of the grooved wheel shaft 0312 and is rotatably connected to the grooved wheel shaft 0312. The grooved wheel 0311 has cylindrical pin slots 03111 evenly distributed radially. Grooved wheel contacts 03110 are evenly distributed circumferentially along the inner diameter of the grooved wheel 0311. Contact switches 03120 are evenly distributed circumferentially along the outer diameter of the grooved wheel shaft 0312. The contact switches 03120 can be triggered by the grooved wheel contacts 03110 to open the loading mechanism 01. The contact switches 03120, the servo motor 021, and the control system 20 are electrically connected.

[0060] The right end face of the Geneva wheel bracket 032 is flush with the right end face of the power shaft 024 and fixed on the frame 05. The Geneva wheel bracket 032 has a through hole in the middle that is concentric with the power shaft 024. The inner diameter of the through hole has continuously and evenly distributed through hole teeth. The right end of the power shaft 024 is fitted with a dial 033. The outer diameter of the dial 033 has continuously and evenly distributed spindle teeth. The spindle teeth correspond one-to-one with the through hole teeth, forming a gap in the middle to fix the Geneva wheel shaft 0312. Multiple rotary switches 031 are fitted inside the dial 033 and the Geneva wheel bracket 032. The dial 033 also has a cylindrical pin 0331 that can be fitted into the cylindrical pin slot 03111.

[0061] The loading mechanism 01 is used to provide loading force to the bar stock, causing the bar stock to bend and generate deflection. The loading mechanism 01 is electrically connected to the control system 20.

[0062] When using it, first insert the grooved wheel shaft 0312 of the rotary switch 031 between the main shaft retaining teeth and the through hole retaining teeth at the corresponding bar stock rotary position;

[0063] When the servo motor 021 starts, the drive gear 0211 drives the power shaft 024 on the driven gear 0241 to rotate via the synchronous belt 023, thereby causing the bar to rotate.

[0064] The cylindrical pin 0331 on the dial 033 on the power shaft 024 rotates circumferentially and engages with the cylindrical pin slot 03111 on the rotary switch 031 on the outer side of the dial 033. Since the grooved wheel shaft 0312 is fixed, the cylindrical pin slot 03111 is moved by the cylindrical pin 0331, causing the grooved wheel 0311 to rotate on the grooved wheel shaft 0312. The grooved wheel contact 03110 on the inner wall of the grooved wheel 0311 touches the contact switch 03120 on the grooved wheel shaft 0312. The contact switch 03120 sends a start signal to the control system 20, and the control system 20 controls the loading mechanism 01 to open, applying a corresponding low stress to the bar stock.

[0065] As the dial 033 continues to rotate, the cylindrical pin 0331 engages with the cylindrical pin slot 03111 of the next rotary switch 031. The contact switch 03120 in the rotary switch 031 is also triggered in the same way. In this manner, the bar stock is loaded with appropriate force at the appropriate loading position until the unloading is completed.

[0066] Furthermore, in the above technical solution, a drive gear 0211 is fixed on the power output end of the servo motor 021, and a driven gear 0241 is sleeved on the power shaft 024. The drive gear 0211 and the driven gear 0241 are connected by a synchronous belt 023. The three-jaw chuck 022 is located at the end of the power shaft 024 away from the synchronous belt 023.

[0067] Furthermore, in the above technical solution, the frame 05 is provided with an adjusting slide rail 051, and a main shaft sleeve block for fixing the power shaft 024 is sleeved on the outside of the power shaft 024. The bottom of the main shaft sleeve block and the groove wheel bracket 032 are slidably connected to the adjusting slide rail 051 through the adjusting slider 052.

[0068] Furthermore, in the above technical solution, one of the adjusting sliders 052 is simultaneously fixed to the bottom of the power shaft 024 and the main shaft sleeve block.

[0069] Furthermore, in the above technical solution, the servo motor 021 is suspended at the bottom of the frame 05 by a sliding rod mechanism. The sliding rod mechanism includes an adjusting slide rod 081 and a motor fixing plate 082. The motor fixing plate 082 is fixedly connected to the servo motor 021. The adjusting slide rod 081 is fixed to one end of the upper surface of the frame 05 near the grooved wheel bracket 032 by a slide rod sleeve block. The adjusting slide rod 081 and the slide rod sleeve block are threadedly rotatably connected. The upper end of the motor fixing plate 082 is fixedly connected to the adjusting slide rod 081.

[0070] In use, slide the clamping and rotating mechanism 02 on the adjusting slide rail 051 to a suitable position, and use the adjusting slide bar 081 to adjust the servo motor 021 to a suitable position.

[0071] like Figure 5-6 As shown, further, in the above technical solution, the loading mechanism 01 includes guide columns 011, hydraulic telescopic cylinders 012, and loading components 013. There are two sets of guide columns 011, symmetrically distributed on both sides of the power shaft 024. The bottom of the guide columns 011 is fixedly connected to the top of the frame 05. A connecting plate 0111 is slidably connected between the two guide columns 011. A fixing plate 0112 is fixedly connected between the tops of the two guide columns 011. The bottom of the connecting plate 0111 is fixedly connected to the loading component 013. The fixing plate 0112 is fixedly connected to the hydraulic telescopic cylinder 012. The telescopic end of the hydraulic telescopic cylinder 012 is fixedly connected to the top of the connecting plate 0111. The hydraulic pipe of the hydraulic telescopic cylinder 012 is connected to the oil tank 0121 at the bottom of the frame 05. The hydraulic telescopic cylinder 012 is electrically connected to the control system 20.

[0072] Among them, component 013 can use the public number as

[0073] The loading mold 403 in Chinese invention patent CN114515966B, "A Cutting and Bending Coordinated Fatigue Low-Stress Blanking Device and Method" (application number CN202210169650.3), includes a connector 4031, a loading frame 4032, and an angle adjustment block 4034. One side of the connector 4031 is fixedly connected to a movable plate 4022. The loading frame 4032 is located below the connector 4031. The angle adjustment block 4034 is located on one side of the loading frame 4032 and is fixedly connected to the connector 4031. The loading mold 403 is connected to the guide post 401 through a follower component 402. Under the action of the threaded rod 4021, the follower component 402 causes the loading mold 403 to move up and down along the direction of the guide post 401, providing loading force to the bar stock, causing the bar stock to bend and generate deflection.

[0074] The top of the loading frame 4032 is provided with a connecting groove 40321, which has a "U"-shaped structure. The bottom of the connector 4031 is embedded in the connecting groove 40321. The connector 4031 and the connecting groove 40321 are connected by bolts. An angle pointer 40322 is provided on one side of the connecting groove 40321. The angle pointer 40322 corresponds to the scale line provided on one side of the connector 4031. The connecting groove 40321 facilitates the cooperation between the loading frame 4032 and the connector 4031, and the angle pointer 40322 makes the angle adjustment of the loading frame 4032 more convenient and quick.

[0075] Angle adjustment block 4034 is located on the side of loading frame 4032 away from cutting mechanism 300. A pad block 4033 is located on the side of loading frame 4032 near angle adjustment block 4034. The pad block 4033 is fixedly connected to loading frame 4032. An angle adjustment rod 4035 is located on one side of pad block 4033. The other end of angle adjustment rod 4035 passes through angle adjustment block 4034 and is provided with quick-release locking member 40351. One side of quick-release locking member 40351 abuts against one side of angle adjustment block 4034. Angle adjustment block 4034 has a right trapezoidal structure, with the inclined side facing pad block 4033. By adjusting the extension length of angle adjustment rod 4035, loading frame 4032 can form different included angles. Quick-release locking member 40351 is used to fix the extension length of angle adjustment rod 4035, which is convenient to adjust and locks firmly and stably.

[0076] In the embodiments of the above invention, a follower bearing 4036 is provided at the center of the loading frame 4032, and a bearing cover 40361 is provided on one side of the follower bearing 4036. The bearing cover 40361 is fixedly connected to the loading frame 4032. The follower bearing 4036 makes follower contact with the outer surface of the bar stock, reducing wear on the surface of the bar stock. The bearing cover 40361 is used to fix the follower bearing 4036 and prevent it from detaching from the loading frame 4032.

[0077] Furthermore, in the above technical solution, each contact switch 03120 corresponds to activating a different extension length of the hydraulic telescopic cylinder 012.

[0078] Bar stock of different materials and parameters can be subjected to reasonable loading forces and loading positions through XFEM. XFEM stands for eXtended Finite Element Method, which is an improvement on the traditional finite element method (FEM).

[0079] Traditional FEMs require meshing complex geometries, which increases the number of meshes, computational cost, and computational error. XFEMs, however, introduce additional degrees of freedom within the element, enabling efficient and accurate boundary simulation without requiring meshing of the geometry. This method is primarily applicable to structures with complex geometries or large deformations, such as fractures, contacts, or interpenetration, effectively improving computational efficiency and accuracy.

[0080] XFEM is an adaptive method that can adapt the mesh according to the shape changes of a broken object, thereby more accurately simulating phenomena such as object breakage and fracture. Moreover, it can perform calculations efficiently without the cumbersome geometric meshing required in the traditional finite element method.

[0081] Furthermore, in the above technical solution, each grooved wheel 0311 has three cylindrical pin slots 03111.

[0082] like Figure 7 The image shows a method for low-stress material preparation using multi-spinning point loading, provided by a second aspect of the present invention. This method is applied to the aforementioned multi-spinning point loading low-stress material preparation device and includes the following steps:

[0083] S1: Bar stock pretreatment, machining V-grooves at the pre-fracture position of the bar stock, and determining the effective loading position of the bar stock, i.e., the rotation point position;

[0084] S2: Install bar stock. Pass the bar stock to be unloaded through the loading component 013, then pass the bar stock through the three-jaw chuck 022 and clamp and fix the bar stock with the three-jaw chuck 022. Install the rotary switch 031 at the position of the rotary switch mechanism 03 corresponding to the rotary point of the bar stock.

[0085] S3: Preset loading force, the control system 20 sets the extension length of the different hydraulic telescopic cylinders 012 corresponding to the grooved wheel shaft 0312 on each grooved wheel shaft 0312, that is, the hydraulic telescopic cylinders 012 apply different loading forces to the bar stock;

[0086] S4: Material unloading is performed. The power of the servo motor 021 is output to the synchronous belt 023, which in turn drives the bar material held on the three-jaw chuck 022 to rotate. The cylindrical pin 0331 on the dial 033 engages with the cylindrical pin slot 03111 on the grooved wheel 0311 of the rotary switch 031, thereby driving the grooved wheel 0311 to rotate on the grooved wheel shaft 0312. This causes the grooved wheel contact 03110 to trigger the contact switch 03120, which activates the hydraulic telescopic cylinder 012 to extend and retract the bar material with a corresponding loading force. The cylindrical pin 0331 on the dial 033 continuously engages with the next rotary switch 031, causing the hydraulic telescopic cylinder 012 to intermittently load the bar material with different forces until cracks appear at the bottom of the V-groove of the bar material. The cracks then continuously expand in the circumferential direction, completing one unloading operation.

[0087] Specifically, the principle of this invention is as follows: Figure 8-9 As shown, a V-groove is first machined on the surface of the metal bar at the pre-cutting position. One end of the V-groove is clamped, and the other end is loaded. Through theoretical research, a certain number of effective loading positions, called rotation points, are determined in the circumference of the bar. A reasonable loading force is then applied sequentially at each rotation point to induce cracks at the bottom of the V-groove, causing the cracks to propagate continuously in the circumference. Through multiple cyclic loading processes, the cracks expand layer by layer, ultimately achieving material breakage.

[0088] The method for locating the rotation point of the bar stock is referenced from "A multiple rolling-point loading method for low-stress equal-radial-depth cropping" in Engineering Fracture Mechanics 282(2023)109207. The paper mentions that, addressing the problem of eccentricity in the instantaneous fracture zone of the bar stock and the resulting poor cross-sectional quality in current low-stress cropping techniques, a low-stress equal-radial-depth cropping method is proposed. This method controls the multi-circumferential equal-depth crack propagation by applying rotation point loading forces at different circumferential positions on the bar stock surface. First, the maximum circumferential stress criterion is applied to give the propagation criteria for surface cracks on the bar stock under single-rotation point loading. Using ABAQUS software, a finite element model of the bar stock under multi-rotation point loading is established, and a rotation point loading test platform is built to conduct rotation point loading tests, verifying the accuracy of the simulation model. Taking 45 steel bars, a commonly used material for blanking, as an example, the XFEM method was used to simulate the longest continuous propagation process of the first-cycle crack at the tip of the V-groove and the multi-cycle propagation process of the circumferential crack. Combined with the proposed material modification parameters, multi-rotation point loading curves for constant-diameter-depth blanking of four different materials—45 steel, Q345 steel, 304 stainless steel, and 6061Al—were obtained. Blanking test results show that multi-rotation point loading can achieve low-stress constant-diameter-depth blanking; compared with the traditional continuous loading method, the instantaneous fracture zone of the bar can be reduced by up to 65%, with virtually no eccentricity, and the cross-sectional quality is significantly improved.

[0089] The appropriate loading force is designed to ensure that, after crack initiation, each subsequent crack propagation reaches its maximum length in the circumferential direction and maintains a consistent depth in the radial direction. Each subsequent propagation should also allow the crack generated by the loading force to connect with existing cracks, thereby achieving the highest crack propagation efficiency.

[0090] For bars of different materials and parameters, reasonable loading forces and loading positions can be obtained using XFEM. Taking a 45 steel bar with a diameter of 15mm and a blank length of 40mm as an example, the crack propagation morphology under five rotation point loadings is as follows: Figure 10 As shown;

[0091] The obtained displacement curve of the entire process of rotary loading is shown in Figure 11. The obtained theoretical value is input into the control operation interface of the equipment, and the rotary switch structure is distributed according to the loading position to realize the low-stress feeding process of multi-rotary loading.

[0092] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A multi-rotation point loading low-stress feeding device, characterized in that, The device includes a frame (05), a loading mechanism (01), a clamping and rotating mechanism (02), and a pivot switch mechanism (03). The loading mechanism (01), the clamping and rotating mechanism (02), and the pivot switch mechanism (03) are all mounted on the frame (05). The loading mechanism (01) and the pivot switch mechanism (03) are respectively located on the left and right sides of the clamping and rotating mechanism (02). The clamping and rotating mechanism (02) includes a servo motor (021), a three-jaw chuck (022), and a power shaft (024). The servo motor (021) is installed at the bottom of the frame (05). The power shaft (024) and the three-jaw chuck (022) are installed on the top surface of the frame (05). The three-jaw chuck (022) is fixedly connected to one end of the power shaft (024) and is coaxial with the power shaft (024). The servo motor (021) is driven by the power shaft (024). The rotary switch mechanism (03) comprises a rotary switch (031), a grooved wheel bracket (032), and a dial (033); the rotary switch (031) includes a grooved wheel (0311) and a grooved wheel shaft (0312), the grooved wheel (0311) is sleeved on the front end of the grooved wheel shaft (0312) and rotatably connected to the grooved wheel shaft (0312); the grooved wheel (0311) has cylindrical pin slots (03111) evenly distributed radially. The Geneva wheel (0311) has Geneva wheel contacts (03110) evenly distributed circumferentially along its inner diameter; the Geneva wheel shaft (0312) has contact switches (03120) evenly distributed circumferentially along its outer diameter. The contact switches (03120) can be triggered by the Geneva wheel contacts (03110) to open the loading mechanism (01). The contact switches (03120), the servo motor (021), and the control system (20) are electrically connected. The right end face of the grooved wheel bracket (032) is flush with the right end face of the power shaft (024) and fixed on the frame (05). The grooved wheel bracket (032) has a through hole in the middle that is concentric with the power shaft (024). The inner diameter of the through hole has continuously and evenly distributed through hole teeth. The right end of the power shaft (024) is fitted with the dial (033). The outer diameter of the dial (033) has continuously and evenly distributed spindle teeth. The spindle teeth correspond one-to-one with the through hole teeth, and a gap is formed in the middle to fix the grooved wheel shaft (0312). Multiple rotary switches (031) are fitted inside the dial (033) and the grooved wheel bracket (032). The dial (033) also has a cylindrical pin (0331) that can be fitted into the cylindrical pin slot (03111). The loading mechanism (01) is used to provide loading force to the bar stock, causing the bar stock to bend and generate deflection. The loading mechanism (01) is electrically connected to the control system (20).

2. The multi-rotation point loading low-stress feeding device according to claim 1, characterized in that, The servo motor (021) has a drive gear (0211) fixed on its power output end, and a driven gear (0241) is sleeved on the power shaft (024). The drive gear (0211) and the driven gear (0241) are connected by a synchronous belt (023). The three-jaw chuck (022) is located at the end of the power shaft (024) away from the synchronous belt (023).

3. The multi-rotation point loading low-stress feeding device according to claim 2, characterized in that, An adjusting slide rail (051) is provided on the frame (05). A main shaft sleeve block for fixing the power shaft (024) is sleeved on the outside of the power shaft (024). The main shaft sleeve block and the bottom of the grooved wheel bracket (032) are slidably connected to the adjusting slide rail (051) through the adjusting slider (052).

4. The multi-rotation point loading low-stress feeding device according to claim 3, characterized in that, One of the adjusting sliders (052) is fixed to both the power shaft (024) and the bottom of the main shaft sleeve.

5. The multi-spinning-point loading low-stress feeding device according to claim 4, characterized in that, The servo motor (021) is suspended at the bottom of the frame (05) via a sliding rod mechanism. The sliding rod mechanism includes an adjusting slide rod (081) and a motor fixing plate (082). The motor fixing plate (082) is fixedly connected to the servo motor (021). The adjusting slide rod (081) is fixed to one end of the upper surface of the frame (05) near the grooved wheel bracket (032) via a slide rod sleeve. The adjusting slide rod (081) is threadedly rotatably connected to the slide rod sleeve. The upper end of the motor fixing plate (082) is fixedly connected to the adjusting slide rod (081).

6. The multi-rotation point loading low-stress feeding device according to claim 5, characterized in that, The loading mechanism (01) includes guide columns (011), a hydraulic telescopic cylinder (012), and a loading assembly (013). Two sets of guide columns (011) are symmetrically distributed on both sides of the power shaft (024). The bottom of each guide column (011) is fixedly connected to the top of the frame (05). A connecting plate (0111) is slidably connected between the two guide columns (011), and a fixing plate (011) is fixedly connected between the tops of the two guide columns (011). 2) The bottom of the connecting plate (0111) is fixedly connected to the loading component (013), the fixing plate (0112) is fixedly connected to the hydraulic telescopic cylinder (012), the telescopic end of the hydraulic telescopic cylinder (012) is fixedly connected to the top of the connecting plate (0111), the hydraulic pipe of the hydraulic telescopic cylinder (012) is connected to the oil tank (0121) at the bottom of the frame (05), and the hydraulic telescopic cylinder (012) is electrically connected to the control system (20).

7. The multi-rotation point loading low-stress feeding device according to claim 6, characterized in that, Each of the contact switches (03120) corresponds to activating a different extension length of the hydraulic telescopic cylinder (012).

8. The multi-spinning-point loading low-stress feeding device according to claim 7, characterized in that, Each of the aforementioned grooved wheel (0311) has three of the aforementioned cylindrical pin slots (03111).

9. A method for low-stress material preparation using multi-spinning point loading, applied to the multi-spinning point loading low-stress material preparation device described in claim 8, characterized in that, Includes the following steps: S1: Bar stock pretreatment, machining V-grooves at the pre-fracture position of the bar stock, and determining the effective loading position of the bar stock, i.e., the rotation point position; S2: Install the bar stock. Pass the bar stock to be unloaded through the loading component (013), then pass the bar stock through the three-jaw chuck (022), and clamp and fix the bar stock with the three-jaw chuck (022). Install the rotary switch (031) on the rotary switch mechanism (03) at the position of the rotary point of the bar stock. S3: Preset loading force, the control system (20) sets the extension length of the grooved wheel shaft (0312) on each grooved wheel shaft (0312) to be different from that of the hydraulic telescopic cylinder (012), that is, the hydraulic telescopic cylinder (012) applies different loading forces to the bar stock; S4: The material is unloaded. Power from the servo motor (021) is output to the synchronous belt (023), which in turn drives the bar stock held in the three-jaw chuck (022) to rotate. The cylindrical pin (0331) on the dial (033) engages with the cylindrical pin slot (03111) on the grooved wheel (0311) of the rotary switch (031), thereby driving the grooved wheel (0311) to rotate on the grooved wheel shaft. (0312) rotates, causing the grooved wheel contact (03110) to trigger the contact switch (03120), opening the hydraulic telescopic cylinder (012) to extend and retract the bar with corresponding loading force; the cylindrical pin (0331) on the dial (033) continuously engages the next rotary switch (031), causing the hydraulic telescopic cylinder (012) to start intermittently to load the bar with different forces until cracks are generated at the bottom of the V-groove of the bar, and the cracks continuously expand in the circumferential direction, completing one feeding.

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