Slow wire electrical discharge wire cutting wire control device and control method thereof

Abstract

This invention relates to the field of wire electrical discharge machining (EDM), and more particularly to a wire feeding control device and method for slow-speed wire EDM. The control device includes a frame, a wire guide mechanism, a tension wheel, a brake, and a controller. The wire guide mechanism is used to feed the electrode wire; the tension wheel is located downstream of the wire guide mechanism; the brake acts on the tension wheel; and the controller is connected to the wire guide mechanism, the tension wheel, and the brake. The electrode wire is sequentially wound around the wire guide mechanism and the tension wheel. The brake is used to adjust the resistance torque of the tension wheel, which acts on the electrode wire to adjust the tension of the electrode wire in real time. This invention achieves tension control in slow-speed wire EDM by changing the magnitude of the resistance torque of the tension wheel through the brake, thereby improving the machining accuracy of slow-speed wire EDM. This is of great significance for improving the manufacturing quality of precision parts, increasing production efficiency, and reducing production costs.

Description

Technical Field

[0001] This invention relates to the field of wire electrical discharge machining (EDM) technology, and more particularly to a wire feed control device and control method for slow wire EDM. Background Technology

[0002] In the field of precision machining, slow wire EDM technology has become an indispensable key process for the manufacturing of many precision parts due to its advantages of high precision and high surface quality. It is widely used in high-end manufacturing industries such as aerospace, electronic information, and precision molds.

[0003] In slow-speed wire EDM, constant speed and tension control of the electrode wire is one of the core factors determining machining quality. Fluctuations in electrode wire speed and tension lead to instability in the machining process, resulting in a series of problems such as decreased machining accuracy, increased surface roughness, and uneven cutting patterns. These problems not only affect the appearance quality of the product but may also reduce its mechanical properties and service life, increasing production costs and scrap rates. When the electrode wire speed fluctuates too much, the discharge gap of the workpiece changes repeatedly, resulting in cumulative accuracy deviations, and the electrode wire is subjected to alternating stress, making the probability of wire breakage much higher than in stable-speed machining. Conversely, when the electrode wire tension is too low, it is prone to vibration during machining, leading to deviations in the cutting trajectory and making it difficult to guarantee machining accuracy; while when the electrode wire tension is too high, the electrode wire is prone to breakage, interrupting the machining process and reducing production efficiency. Therefore, achieving tension control in slow-speed wire EDM is of great significance for improving the manufacturing quality of precision parts, increasing production efficiency, and reducing production costs. Summary of the Invention

[0004] This invention provides a wire feed control device and method for slow wire electrical discharge machining, which solves the defect in the prior art that the machining process is unstable due to the fluctuation of electrode wire tension.

[0005] This invention provides a wire feeding control device for slow wire electrical discharge machining, comprising: frame; A wire guiding mechanism, mounted on the frame, is used to transport electrode wires; The tension wheel is rotatably mounted on the frame and located downstream of the wire guiding mechanism; A brake is mounted on the frame and acts on the tension wheel; The controller is connected to the wire guide mechanism, the tension wheel, and the brake, respectively. The electrode wire is sequentially wound around the wire guide mechanism and the tension wheel. The brake is used to adjust the resistance torque of the tension wheel, and the resistance torque acts on the electrode wire to adjust the tension of the electrode wire in real time.

[0006] According to one embodiment of the present invention, the guide wire mechanism further includes: Wire storage tube; A speed detection unit is used to detect the speed of the electrode wire, and the controller is signal-connected to the speed detection unit; A first driving unit is connected to the controller and the wire storage drum. The controller is used to control the first driving unit according to the speed of the electrode wire to adjust the wire output speed of the wire storage drum.

[0007] According to one embodiment of the present invention, the guide wire mechanism further includes: Multiple first guide rollers are rotatably mounted on the frame and located downstream of the wire storage drum, and the speed detection unit is located between two of the first guide rollers.

[0008] According to one embodiment of the present invention, the speed detection unit includes: A cam is rotatably mounted on the frame, and one side of the cam has a surface to be measured; A connecting rod, one end of which is connected to the cam and can rotate synchronously with the cam; The second guide wheel is located between the two first guide wheels, and the other end of the connecting rod is connected to the second guide wheel; A limiting block is provided on the frame; A position sensor is disposed facing the surface to be measured of the cam, and is used to detect changes in the distance between the position sensor and the surface to be measured; the controller is connected to the position sensor. When the connecting rod is in the first state, the connecting rod rests on the limiting block; when the connecting rod is in the second state, the connecting rod rotates and lifts off the limiting block; the controller adjusts the wire output speed of the wire storage drum according to the distance change detected by the position sensor.

[0009] According to one embodiment of the present invention, the guide wire mechanism further includes: The take-up roller is mounted on the frame and located downstream of the tension roller; The second drive unit is connected to the controller.

[0010] According to one embodiment of the present invention, it further includes: A tension sensor, located downstream of the tension wheel and connected to the controller, is used to detect the tension of the electrode wire in real time. The controller controls the brake based on the obtained tension of the electrode wire.

[0011] According to one embodiment of the present invention, it further includes: Multiple pressure rollers are provided on the outside of the tension roller and are evenly distributed at intervals along the circumference of the tension roller, for pressing the electrode wire onto the tension roller.

[0012] According to one embodiment of the present invention, the brake is a hysteresis brake, which is connected to a current source controller. The controller controls the hysteresis brake to change the magnitude of the resistance torque of the tension wheel through the current source controller.

[0013] The present invention also provides a control method for a wire cutting control device for slow wire EDM according to the present invention, comprising: Perform tension calibration and solve for the tension control parameters according to the fitting formula; Obtain a preset tension value, substitute the preset tension value into the fitting formula, and determine the control parameters of the controller; The controller's control parameters are adjusted by comparing the preset tension value with the detected tension value.

[0014] According to one embodiment of the present invention, it further includes: Obtain the preset speed and convert it into control parameters for the take-up wheel; The wire feeding speed of the wire storage drum is adjusted according to the distance change detected by the position sensor.

[0015] This invention provides a wire feeding control device and method for slow-speed wire EDM. The control device includes a frame, a wire guide mechanism, a tension wheel, a brake, and a controller. The wire guide mechanism is mounted on the frame and is used to feed the electrode wire. The tension wheel is rotatably mounted on the frame and located downstream of the wire guide mechanism. The brake is mounted on the frame and acts on the tension wheel. The controller is connected to the wire guide mechanism, the tension wheel, and the brake. The electrode wire is sequentially wound around the wire guide mechanism and the tension wheel. The brake is used to adjust the resistance torque of the tension wheel, which acts on the electrode wire to adjust the tension of the electrode wire in real time. This invention provides a wire feeding control device for slow-speed wire EDM, which changes the magnitude of the resistance torque of the tension wheel through the brake, thereby achieving tension control in slow-speed wire EDM. This improves the machining accuracy of slow-speed wire EDM and is of great significance for improving the manufacturing quality of precision parts, increasing production efficiency, and reducing production costs.

[0016] In addition, by applying a hysteresis brake to the tension wheel and adjusting its resistance torque, the tension of the hysteresis brake is increased slowly to prevent the tension from being applied too quickly and causing impact on the electrode wire. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the wire cutting control device for slow wire EDM provided in one embodiment of the present invention.

[0019] Figure 2 This is a schematic diagram of a slow wire EDM wire cutting control device provided in one embodiment of the present invention.

[0020] Figure 3 This is a schematic flowchart of the control method of the wire cutting control device for slow wire EDM provided in one embodiment of the present invention.

[0021] Figure 4 This is a schematic flowchart of the control method of the wire cutting control device for slow wire EDM provided in one embodiment of the present invention.

[0022] Figure label: 1. Feeding servo motor; 2. Wire storage drum; 3. First guide wheel; 4. Second guide wheel; 5. Third guide wheel; 6. First pressure wheel; 7. Tension wheel; 8. Second pressure wheel; 9. Third pressure wheel; 10. Hysteresis brake; 11. Tension sensor; 12. Connecting rod; 13. Rotating shaft; 14. Limit block; 15. Fourth guide wheel; 16. Take-up wheel; 17. Take-up servo motor; 18. Position sensor; 19. Cam; 20. CNC system; 21. PLC controller; 22. Master stack driver; 23. Slave stack driver; 24. Power transmitter; 25. Current source controller. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0024] In the description of this embodiment, 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", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this embodiment and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this embodiment.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this embodiment, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0026] In this embodiment, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," "link," and "fix" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this embodiment based on the specific circumstances.

[0027] In embodiments of the present invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0028] The following is combined Figure 1 and Figure 2 This invention describes a wire feeding control device for slow-speed wire EDM. The device includes a frame, a wire guide mechanism, a tension wheel 7, a brake, and a controller.

[0029] The wire guide mechanism is mounted on the frame and is used to transport the electrode wire; the tension wheel 7 is rotatably mounted on the frame and located downstream of the wire guide mechanism; the brake is mounted on the frame and acts on the tension wheel 7; the controller is connected to the wire guide mechanism, the tension wheel 7 and the brake respectively.

[0030] The electrode wire is wound sequentially around the guide wire mechanism and the tension wheel 7. The brake is used to adjust the resistance torque of the tension wheel 7. The resistance torque acts on the electrode wire to adjust the tension of the electrode wire in real time.

[0031] Specifically, the frame serves as the support and mounting structure for this device, and the various components of the device can be mounted on the frame. The frame can be a plate-like structure, not shown in the figure. The wire guide mechanism is used to guide and transport the electrode wire downstream.

[0032] Specifically, the tension wheel 7 is a guide roller that applies controllable tension to a flexible material in operation through its own weight, spring force, cylinder thrust, or in conjunction with a braking / drive device; in this invention, the tension wheel 7 applies controllable tension to the electrode wire to control the tension of the electrode wire.

[0033] Specifically, the output end of the brake is connected to the tension wheel 7, causing the tension wheel 7 to generate a resistance torque. The brake changes the magnitude of the resistance torque of the tension wheel 7, thereby controlling the tension of the electrode wire. In actual operation, constant tension wire feeding is achieved by utilizing the elastic deformation of the electrode wire.

[0034] Preferably, the brake is a hysteresis brake 10, and the controller controls the hysteresis brake 10 to change the magnitude of the resistance torque through the current source controller 25.

[0035] Specifically, the controller can be a PLC controller, used in conjunction with the CNC system 20. The controller is used to control the operating conditions of each component in this device, and controls the operating conditions of the corresponding components by receiving feedback detection data.

[0036] During the use of this device, the electrode wire is guided by the wire guide mechanism and the tension wheel 7 in sequence to complete the wire feeding. During the wire feeding process, the resistance torque of the tension wheel 7 is changed by the brake, thereby realizing the control of the electrode wire tension and ensuring constant tension wire feeding.

[0037] This invention provides a wire feeding control device for slow-speed wire EDM, comprising: a frame, a wire guide mechanism, a tension wheel 7, a brake, and a controller. The wire guide mechanism is mounted on the frame and is used to feed the electrode wire; the tension wheel 7 is rotatably mounted on the frame and located downstream of the wire guide mechanism; the brake is mounted on the frame and acts on the tension wheel 7; the controller is connected to the wire guide mechanism, the tension wheel 7, and the brake. The electrode wire is sequentially wound around the wire guide mechanism and the tension wheel 7. The brake is used to adjust the resistance torque of the tension wheel 7, which acts on the electrode wire to adjust the tension of the electrode wire in real time. This invention provides a wire feeding control device for slow-speed wire EDM, which changes the magnitude of the resistance torque of the tension wheel 7 through the brake, thereby achieving tension control in slow-speed wire EDM and improving the machining accuracy. This is of great significance for improving the manufacturing quality of precision parts, increasing production efficiency, and reducing production costs.

[0038] In one embodiment of the present invention, the wire guiding mechanism further includes: a wire storage drum 2, a speed detection unit, and a first driving unit. The speed detection unit detects the speed of the electrode wire, and the controller is signal-connected to the speed detection unit. The first driving unit is connected to the controller and the wire storage drum 2, and the controller controls the first driving unit according to the speed of the electrode wire to adjust the wire output speed of the wire storage drum 2. In this embodiment, the wire storage drum 2 stores the electrode wire. The speed detection unit detects the wire feeding speed and feeds it back to the controller. The controller compares the user-preset wire feeding speed with the detected current wire feeding speed and controls the rotational speed of the first driving unit, thereby achieving wire feeding speed regulation. In actual use, the controller controls the first driving unit to ensure constant wire feeding speed.

[0039] In one embodiment of the present invention, the wire guiding mechanism further includes: a plurality of first wire guiding wheels, rotatably mounted on the frame and located downstream of the wire storage cylinder 2, with a speed detection unit disposed between two of the first wire guiding wheels. Specifically, the wire guiding mechanism consists of a plurality of first wire guiding wheels, which are arranged sequentially along the order of electrode wire feeding. The electrode wire passes through each of the first wire guiding wheels in sequence, and is guided downstream by the first wire guiding wheels. A speed detection unit is disposed between two of the first wire guiding wheels. Preferably, if two first wire guiding wheels are provided, the speed detection unit is disposed between these two first wire guiding wheels. It is understood that the first wire guiding wheels are mounted on the frame via a rotating shaft 13 to achieve rotation.

[0040] Preferably, the first guide wheel and the second guide wheel adopt the same structure of guide wheels, such as... Figure 1In the illustrated embodiment, four guide wheels are provided: a first guide wheel 3, a second guide wheel 4, a third guide wheel 5, and a fourth guide wheel 15, which are located downstream of the wire storage drum 2 and guide the electrode wire from the working area to the take-up wheel 16. The first guide wheel 3 and the third guide wheel 5 are multiple first guide wheels as described in the above embodiment, and the second guide wheel 4 is a second guide wheel as described in the above embodiment. The fourth guide wheel 15 is located between the working area downstream of the tension sensor 11 and the take-up wheel 16, and guides the electrode wire from the working area to the take-up wheel 16.

[0041] Preferably, the first guide wheel and / or the second guide wheel have V-shaped grooves. Specifically, the guide wheel is a V-shaped single-groove guide wheel, which facilitates the routing and positioning of the electrode wire. In this embodiment, the first guide wheel, the second guide wheel (i.e., the first guide wheel 3, the second guide wheel 4, the third guide wheel 5), and the fourth guide wheel 15 are all V-shaped single-groove guide wheels. The electrode wire is always in contact with the bottom of the V-shaped single groove, ensuring accurate positioning of the electrode wire and preventing it from slipping out, thereby overcoming the problem of electrode wire vibration.

[0042] In one embodiment of the present invention, the speed detection unit includes: a cam 19, a connecting rod 12, a second guide wheel, a limiting block 14, and a position sensor 18. The cam 19 is rotatably mounted on the frame, and one side of the cam 19 has a surface to be measured. One end of the connecting rod 12 is connected to the cam 19 and can rotate synchronously with the cam 19. The second guide wheel is located between two of the first guide wheels, and the other end of the connecting rod 12 is connected to the second guide wheel. The limiting block 14 is mounted on the frame. The position sensor 18 is positioned facing the surface to be measured on the cam 19 and is used to detect changes in the distance between the position sensor 18 and the surface to be measured. A controller is connected to the position sensor 18. When the connecting rod 12 is in a first state, the connecting rod 12 rests on the limiting block 14. When the connecting rod 12 is in a second state, the connecting rod 12 rotates and lifts off the limiting block 14. The controller adjusts the wire output speed of the wire storage drum 2 according to the distance change detected by the position sensor 18.

[0043] In the above embodiment, cam 19 is mounted on the back of the frame via shaft 13. Position sensor 18 is fixed on the back of the frame and located near cam 19, and position sensor 18 is directly connected to the PLC controller. One end of connecting rod 12 is connected to cam 19 via shaft 13 and mounted on the front of the frame. Connecting rod 12 and cam 19 rotate synchronously via shaft 13. During rotation, the distance between the surface to be measured of cam 19 and the sensing end of position sensor 18 changes, and this distance change is detected by position sensor 18. The other end of connecting rod 12 is connected to the second guide wheel. The second guide wheel is connected to the other end of connecting rod 12 via rotating shaft 13, but it is not connected to the frame. This allows the second guide wheel to move up and down due to the action of the electrode wire during wire feeding, thereby driving connecting rod 12 to rotate around one end of cam 19. In the initial state (no wire feeding state), the middle part of the connecting rod 12 overlaps the limiting block 14, and the second guide wheel is located at the bottom position. When the electrode wire starts to feed, the second guide wheel and the connecting rod 12 are lifted upward under the actuation of the electrode wire, and the distance between the cam 19 and the position sensor 18 changes accordingly. The controller controls the wire feeding speed of the wire storage drum 2 by acquiring the data monitored in real time by the position sensor 18.

[0044] In one embodiment of the present invention, the yarn guiding mechanism further includes a take-up roller 16 and a second drive unit. The take-up roller 16 is mounted on the frame and located downstream of the tension roller 7; the second drive unit is connected to a controller. Specifically, the first drive unit uses a yarn feeding servo motor 1, and the second drive unit uses a yarn feeding servo motor 17. Both the yarn feeding servo motor 1 and the yarn feeding servo motor 17 are controlled by the controller.

[0045] In one embodiment of the present invention, the wire feeding control device for slow wire EDM further includes: a tension sensor 11, located downstream of the tension wheel 7 and connected to the controller, for real-time detection of the electrode wire tension; the controller controls the brake based on the obtained electrode wire tension. Specifically, by setting the tension sensor 11 downstream of the tension wheel 7, the tension of the electrode wire is monitored in real time and fed back to the controller. The controller compares the user-preset tension with the detected tension, thereby controlling the brake to adjust the resistance torque of the tension wheel 7, and thus adjusting the electrode wire tension. The tension sensor 11 is arranged on the central axis of the tension wheel 7 and the lower guide wheel, above the working area, so that the electrode wire does not undergo arbitrary twisting deformation. The tension sensor 11 is fixed on the frame above the wire guide nozzle. The tension sensor 11 is connected to a transmitter to convert the analog signal into a digital signal, and the power transmitter 24 is connected to the PLC controller.

[0046] In one embodiment of the present invention, the wire feeding control device for slow wire EDM further includes: multiple pressure rollers, which are disposed on the outside of the tension roller 7 and evenly distributed at intervals along the circumference of the tension roller 7, for pressing the electrode wire onto the tension roller 7. Specifically, by setting multiple pressure rollers on the outside of the tension roller 7 and evenly pressing the tension roller 7, constant tension wire feeding is achieved by utilizing the elastic deformation of the electrode wire through the frictional resistance between the multiple pressure rollers and the tension roller 7, during which the electrode wire and the pressure rollers do not slip relative to each other. Preferably, three pressure rollers are set on the outside of the tension roller 7, and the electrode wire passes through the three pressure rollers and the tension roller 7 in sequence.

[0047] In one embodiment of the present invention, the pressing wheel is a smooth guide wheel or a pressing tension wheel 7; the tension wheel 7 is a smooth guide wheel, preferably, the tension wheel 7 is a guide wheel made of smooth metal material.

[0048] In one embodiment of the present invention, the brake is a hysteresis brake 10, which is connected to a current source controller 25. The controller controls the hysteresis brake 10 to change the resistance torque of the tension wheel 7 via the current source controller 25. Specifically, the input terminal of the hysteresis brake 10 is connected to the current source controller 25 to convert the digital signal into an analog signal, and the current source controller 25 is connected to a PLC controller. In this embodiment, the tension applied by the hysteresis brake 10 increases slowly to prevent the tension from being applied too quickly and causing impact on the electrode wire.

[0049] Based on the description in the above embodiments, as Figure 1 As shown, the wire feeding control device for slow wire EDM of the present invention has a frame equipped with a wire storage drum 2, a first guide wheel 3, a second guide wheel 4, a third guide wheel 5, a first pressure wheel 6, a second pressure wheel 8, a third pressure wheel 9, a tension wheel 7, a tension sensor 11, a fourth guide wheel 15, and a take-up wheel 16 arranged in sequence along the wire feeding path of the electrode wire.

[0050] The wire storage drum 2 is connected to the wire feeding servo motor 1, and the wire take-up wheel 16 is connected to the wire take-up servo motor 17. Both the wire feeding servo motor 1 and the wire take-up servo motor 17 are connected to corresponding DC servo motor drivers. The DC servo motor drivers and the position sensor 18 are both connected to the PLC controller. The hysteresis brake 10 is connected to the corresponding current source controller 25, and the tension sensor 11 is connected to the current transmitter. Both the current transmitter and the current source controller 25 are connected to the PLC controller.

[0051] like Figure 3 and Figure 4 As shown, the present invention also provides a control method for a slow wire EDM wire cutting control device, which includes the following steps: S100. Perform tension calibration and solve for the tension control parameters according to the fitting formula. S101. Obtain the preset tension value, substitute the preset tension value into the fitting formula, and determine the control parameters of the controller. S102. Adjust the controller parameters by comparing the preset tension value with the detected tension value.

[0052] Specifically, the above control method is for electrode wire tension control, and its detailed steps are shown in steps S11 to S13: S11. The user sets the wire feeding speed through the CNC system 20. v After 0, the PLC controller calculates the mechanical transmission ratio of the take-up roller 16 and adjusts the wire feeding speed. v The value of 0 is converted into the rotational speed of the take-up servo motor at 17. n 1. The PLC controller controls the DC servo motor driver to drive the take-up servo motor 17 at the specified speed. n 1. Rotating at a constant speed, the take-up wheel 16 drags the electrode wire outward; S12. The downward movement of the electrode wire forces the second guide wheel on the connecting rod 12 to move upward. The movement of the connecting rod 12 forces the rotating shaft 13 and the cam 19 to rotate together. The position sensor 18 detects the distance between the shaft and the cam 19. d The position sensor 18 will change the distance value. d Output to the PLC controller; S13, PLC controller based on distance value D = d - d The size of 0 ( d 0 represents the distance between position sensor 18 and cam 19 when connecting rod 12 is engaged with limit block 14, controlling the rotational speed of the unwinding servo motor 1. n 2. The movement of link 12 is equivalent to a mechanical proportional controller; link 12 will transmit the deviation signal. D Converted proportionally to the speed of the wire feeding servo motor 1 n The control action of 2 ensures that the wire storage drum 2 completes the variable speed wire feeding and does not cause wire to fall off.

[0053] In one embodiment, the above control method is further specifically as follows: S11. The user sets the wire feeding speed on the CNC system panel 20. v After reaching 0, the PLC controller acquires the wire feeding speed value. After calculating the mechanical transmission ratio of the take-up roller 16, the PLC controller sets the wire feeding speed... v The value of 0 is converted into the rotational speed of the take-up servo motor at 17. n 1. Then, the rotation speed value is transmitted from the stack driver 23 to the take-up servo motor 17. The take-up servo motor 17 drives the take-up wheel 16 to rotate the electrode wire at the specified speed. vThe wire is dragged out of the equipment to ensure a constant speed of wire feeding. During this process, the take-up roller 16 applies constant pressure to the electrode wire, forcing the electrode wire to undergo elastic deformation and flatten as it passes through the take-up roller 16. This prevents slippage between the electrode wire and the take-up roller 16 and ensures the electrode wire speed in the working area. v and tension F Constant.

[0054] S12, the downward movement of the electrode wire forces the second guide wheel on the connecting rod 12 to move upward. The movement of the connecting rod 12 forces the rotating shaft 13 and the cam 19 to rotate together. The position sensor 18 detects the distance to the cam 19. d The position sensor 18 will change the distance value. d The output is sent to the PLC controller. In this invention, when the connecting rod 12 is on the limit block 14, the position sensor 18 and the cam 19 are in a close contact state. At this time, the instantaneous distance value detected by the position sensor 18 of the cam 19 is... d 0.

[0055] S13, the PLC controller calculates the magnitude of the distance deviation based on the distance value fed back by the position sensor 18, that is... D = d - d 0. The PLC controller controls the speed of the unwinding servo motor 1. n 2. Accelerate the rotation speed of the wire storage drum 2. During this process, the speed of the wire feeding servo motor 1 will be increased. v 2 is not constant; its rotational speed is determined by the distance value fed back by position sensor 18 and the initial position distance value. d The difference of 0 D Decision. The greater the upward distance of link 12, the greater the difference. D It will increase; the PLC controller controls the speed of the unwinding servo motor 1. v 2. As the upward distance of connecting rod 12 increases, the speed of the wire feeding servo motor 1 also increases. v 2. The increase will also slow down. The movement of link 12 is equivalent to a mechanical proportional controller; link 12 will transmit the deviation signal. D Converted proportionally to the speed of the wire feeding servo motor 1 v 2. Control Actions. Simultaneously, the presence of connecting rod 12 provides a certain amount of electrode wire allowance in the working area, preventing speed and tension loss of control when cutting thick workpieces due to excessive feed speed of the feed axis or significant changes in wire feed speed. The up-and-down movement of connecting rod 12 keeps the electrode wire on the frame stable, ensuring that the electrode wire in the working area always maintains its rated wire speed. v Run the system to avoid problems such as blunt edges and corners, and excessive straightness.

[0056] In one embodiment of the present invention, the control method of the slow wire EDM wire cutting control device further includes: S201. Obtain the preset speed and convert the preset speed into control parameters for the take-up wheel 16; S202. Adjust the wire output speed of the wire storage drum 2 according to the distance change detected by the position sensor 18. Specifically, the above control method is for electrode wire speed control, and its specific steps are detailed in steps S21 to S25.

[0057] S21. Before tension control, the equipment needs to be calibrated. The PLC controller actively controls the current source controller 25 to increase the control signal in sequence. The PLC controller stores the current source control signal and the tension value fed back by the tension sensor 11 in the register and solves the tension control parameters under this working condition according to the fitting formula. S22. After the user sets the tension value through the CNC system 20, the PLC controller compares the tension value fed back by the tension sensor 11 with the set tension value, and substitutes the set tension value into the fitting formula to solve the current source control signal corresponding to the tension value. S23, the PLC controller controls the hysteresis brake 10 to change the magnitude of the resistance torque through the current source controller 25. Constant tension wire feeding is achieved by utilizing the elastic deformation of the electrode wire through the frictional resistance between the pressure wheel and the tension wheel 7.

[0058] In one embodiment, the above control method is further specifically as follows: The S21 electrode wire tension calibration process is completed using a PLC controller, tension sensor 11, current source, and hysteresis brake 10. The PLC controller continuously sends control signals to the current source controller 25, causing the current source controller 25 to continuously output current to control the hysteresis brake 10. I Control current I The tension sensor 11 continuously collects the actual tension of the electrode wire during the process of gradually increasing the interval from zero to 1 mA until the wire breaks. F In this case, a current source is built in the PLC to output each current. I Magnitude of the actual tension value of the electrode wire F The mapping relationship between the experimental data and the data is established and stored in a register. This data is then transmitted to the CNC system 20, which is equipped with a MATLAB computing environment. Based on the experimental data, the data is fitted using a formula... Perform parameter fitting to obtain the parameters in the fitting formula. , , , , The tension control curve is obtained, and the calculated parameters are written back to the PLC controller register for easy recall during tension control. Since the parameters of the fitting formula remain unchanged after tension calibration, the tension control curve is unique in actual operation, and there is no issue with the tension detected by tension sensor 11. F The phenomenon of control parameter oscillation caused by negative feedback. Under normal circumstances, the electrode wire tension calibration process needs to be automatically performed every ten days. If the situation in step S25 occurs, calibration will be performed before the next processing.

[0059] S22. After the user sets the tension value on the CNC system panel 20, the PLC controller obtains the set tension value. F 0. The PLC controller compares the tension value fed back in real time by the tension sensor 11. F Determine whether the set tension value is greater than or equal to the actual tension value. F Then the PLC controller will control the tension value. F Substitute 0 into the formula, and simultaneously call the parameters in the PLC controller register. , , , , Substitute the values ​​into the fitting formula. Perform a rapid solution to determine the control current of the current source controller 25 at this time. .

[0060] S23. When the set tension value is greater than the actual tension value ( F 0≥ F The PLC controller directly controls the hysteresis brake 10 to change the resistance torque through the current source controller 25. T f The size makes the take-up reel 16 more difficult to drive, and the control signal from the PLC controller to the current source... I From the original parameters I Gradually increase from 0 to the specified value I This makes the resistance torque of the hysteresis brake 10 T f The application is increased slowly to avoid sudden increases in resistance torque. T f This causes a significant instantaneous impact on the system. The control signal output by the current source controller 25... I The change is made by the PLC controller using a delay module and the PLC cycle together. Each cycle increases the current value by 1mA until it reaches the electrode wire tension calibration value. I， The entire control signal I The change in the rising time should be controlled within 1 second.

[0061] Due to the friction between the pressure roller and the tension roller 7, the electrode wire will not slip relative to each other. However, as the take-up roller 16 continues to run at a constant speed, it continuously pulls the electrode wire out of the equipment. Due to the interaction of forces, the resistance torque generated by the hysteresis brake 10 connected to the tension roller 7 at this time... T f This tension is also applied to the electrode wire, which will maintain this tension. F Continuous exercise.

[0062] S24. When the set tension value is less than the actual tension value ( F 0 < F Actual tension value F The larger value indicates that the hysteresis brake 10 is in operation at this time, applying tension to the electrode wire. F Since the working principle of the hysteresis brake 10 relies on external excitation current... I The magnetic field generated by the current magnetizes the internal hysteresis material, forming a working magnetic flux, resulting in a faster response speed compared to magnetic powder brakes. If the excitation current is increased after the internal hysteresis material is magnetized, i.e. I ≥ I If the value is 0, the hysteresis material can be further magnetized, and the electrode wire tension can be applied by following step S23.

[0063] However, if the internal hysteresis material is magnetized, the excitation current decreases. I The hysteresis brake 10 will retain a large excitation current from the previous operation. I The residual magnetism in the hysteresis brake 10 can directly lead to tension loss control in the system, severely affecting the operation of the electrode wire. Therefore, demagnetizing the hysteresis brake 10 is a core operation to ensure its repeatability. The demagnetization method for the hysteresis brake 10 is to slowly reduce the excitation current of the excitation coil of the hysteresis brake 10. I To eliminate residual magnetism, a gradually weakening alternating magnetic field is used. Therefore, the PLC controller first needs to control the control signal of the current source controller 25. I From existing control signals I Demagnetize by gradually decreasing the tension signal from 0 to 0, and then gradually increasing the control signal from 0 to the set tension value. I This completes the change in electrode wire tension. The control signal output by the current source controller 25... I The changes are divided into two parts. First, the PLC controller controls the existing current value in each cycle. I Decrease 0 by 1mA until I = 0 The entire control signal I The change in current value from zero should be completed within 1 second. Then, the PLC controller operates on the existing current value according to step S23 for each cycle until... I =0 The calculation in step S22, where the electrode wire tension is increased, is as follows: I size.

[0064] S25. After the current source controller 25 completes the PLC control command, the PLC controller will continuously collect the tension value fed back by the tension sensor 11 in real time. F ,when F 0≠ F At that time, the PLC controller will transmit the real-time tension. F Inaccurate information is fed back to the CNC system 20, which records the inaccurate information and, before the next machining operation, controls the PLC controller to automatically recalibrate the tension value and recalculate the parameters in the CNC system 20. , , , , The parameters are then written into the PLC controller register to control the electrode wire tension. F Precise control of size during each processing step.

[0065] It is understandable that the above control methods and programs are integrated into the PLC controller.

[0066] When the PLC controller communicates with the two drives, the same baud rate is set. The instruction content is written in ASCII code format and the check bit character is automatically calculated by the check program. The PLC controller is connected to the master stack driver 22 through RS485 serial port. The two drives communicate with each other through RJ45 ports and are respectively formed as master stack driver 22 and slave stack driver 23 based on EtherCAT protocol.

[0067] Both the take-up servo motor 17 and the unwind servo motor 1 are DC servo motors. After receiving instructions from the PLC controller via the Modbus protocol, the main stack driver 22 converts the low-voltage instructions into power signals through its internal control circuit and outputs them to the DC servo motors. After receiving the power signals from the driver, the DC servo motors drive the load to start rotating. The built-in encoder of the DC servo motors can detect the actual speed of the motor in real time and send pulse signals back to the servo driver. The slave stack driver 23 actively sends feedback information to the main stack driver 22, and then the main stack driver 22 feeds back the speed information of the two DC servo motors to the PLC controller.

[0068] The PLC controller sends working instructions to the main stack driver 22 and the current source controller 25, including setting the electrode wire feeding speed and electrode wire tension, all of which are input through the operation interface of the CNC system 20.

[0069] In summary, the control device and method of this invention can adjust the wire feeding speed and slight tension of the electrode wire. A stable speed maintains a uniform discharge gap, reducing dimensional deviations and form and position tolerances, thus meeting the high precision requirements of precision parts. The tension applied by the hysteresis brake increases slowly, preventing excessively rapid tension application from impacting the electrode wire. The PLC controller monitors the changes in wire feeding speed and tension in real time, enabling precise adjustment of these parameters, significantly improving the machining accuracy and reliability of slow-wire EDM machines.

[0070] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0071] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A wire feed control device for slow wire electrical discharge machining, characterized in that, include: frame; A wire guiding mechanism, mounted on the frame, is used to transport electrode wires; Tension wheel (7) is rotatably mounted on the frame and located downstream of the wire guide mechanism; A brake is mounted on the frame and acts on the tension wheel (7). The controller is connected to the wire guide mechanism, the tension wheel (7), and the brake, respectively. The electrode wire is wound sequentially around the wire guide mechanism and the tension wheel (7). The brake is used to adjust the resistance torque of the tension wheel (7). The resistance torque acts on the electrode wire to adjust the tension of the electrode wire in real time.

2. The wire feed control device for slow wire EDM according to claim 1, characterized in that, The guide wire mechanism further includes: Wire storage tube (2); A speed detection unit is used to detect the speed of the electrode wire, and the controller is signal-connected to the speed detection unit; The first driving unit is connected to the controller and the wire storage drum (2). The controller is used to control the first driving unit according to the speed of the electrode wire to adjust the wire output speed of the wire storage drum (2).

3. The wire feed control device for slow wire EDM according to claim 2, characterized in that, The guide wire mechanism further includes: Multiple first guide rollers are rotatably mounted on the frame and located downstream of the wire storage cylinder (2), and the speed detection unit is located between two of the first guide rollers.

4. The wire feed control device for slow wire EDM according to claim 3, characterized in that, The speed detection unit includes: A cam (19) is rotatably mounted on the frame, and one side of the cam (19) has a surface to be measured. The connecting rod (12) is connected at one end to the cam (19) and can rotate synchronously with the cam (19); The second guide wheel is located between the two first guide wheels, and the other end of the connecting rod (12) is connected to the second guide wheel; A limiting block (14) is provided on the frame; A position sensor (18) is disposed facing the surface to be measured of the cam (19) and is used to detect the change in distance between the position sensor (18) and the surface to be measured. The controller is connected to the position sensor (18). When the connecting rod (12) is in the first state, the connecting rod (12) is attached to the limiting block (14); when the connecting rod (12) is in the second state, the connecting rod (12) rotates and is lifted off the limiting block (14); the controller adjusts the wire output speed of the wire storage drum (2) according to the distance change detected by the position sensor (18).

5. The wire feed control device for slow wire EDM according to claim 2, characterized in that, The guide wire mechanism further includes: The take-up roller (16) is mounted on the frame and located downstream of the tension roller (7); The second drive unit is connected to the controller.

6. The wire feed control device for slow wire EDM according to claim 1, characterized in that, Also includes: A tension sensor (11), located downstream of the tension wheel (7) and connected to the controller, is used to detect the tension of the electrode wire in real time; The controller controls the brake based on the obtained tension of the electrode wire.

7. The wire feed control device for slow wire EDM according to claim 1, characterized in that, Also includes: Multiple pressing rollers are provided on the outside of the tension roller (7) and evenly distributed at intervals along the circumference of the tension roller (7) to press the electrode wire onto the tension roller (7).

8. The wire feed control device for slow wire EDM according to any one of claims 1 to 7, characterized in that, The brake is a hysteresis brake (10), which is connected to a current source controller (25). The controller controls the hysteresis brake (10) to change the resistance torque of the tension wheel (7) through the current source controller (25).

9. A control method for a wire cutting control device for slow wire EDM according to any one of claims 1 to 8, characterized in that, include: Perform tension calibration and solve for the tension control parameters according to the fitting formula; Obtain a preset tension value, substitute the preset tension value into the fitting formula, and determine the control parameters of the controller; The controller's control parameters are adjusted by comparing the preset tension value with the detected tension value.

10. The control method of the wire feeding control device for slow wire EDM according to claim 9, characterized in that, Also includes: Obtain the preset speed and convert the preset speed into the control parameters of the take-up wheel (16); The output speed of the wire storage drum (2) is adjusted according to the distance change detected by the position sensor (18).

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