Turning tool changing mechanism, numerical control lathe applying turning tool changing mechanism and control method of turning tool changing mechanism

Abstract

The invention relates to the technical field of numerical control lathes, and discloses a turning tool changing mechanism, a numerical control lathe applying the turning tool changing mechanism and a control method of the numerical control lathe, the turning tool changing mechanism comprises a swing arm unit, a tool rest unit and a tool magazine unit, the swing arm unit and the tool rest unit are arranged on a turning tool moving frame, and the tool magazine unit is arranged on a fixing frame; the tool rest unit comprises a turning tool mounting assembly, the turning tool mounting assembly comprises a turning tool fixing frame, a turning tool mounting shaft and a turning tool mounting sensor, the swing arm unit comprises a rotating driver, a linear driver and a clamping jaw, the linear driver comprises a shell, an arm shaft and a piston, and the swing arm unit further comprises an arm shaft displacement sensor and a mounting cover. The tool magazine unit is fixed, the swing arm unit and the tool rest unit are integrated on the turning tool moving frame, the tool changing efficiency is improved, meanwhile, the influence on the turning tool machining precision is reduced, and the problem that a traditional tool changing mechanism is low in turning tool changing efficiency is solved.

Description

Technical Field

[0001] This invention relates to the field of CNC lathe technology, and in particular to a tool changing mechanism and a CNC lathe using the same, and a control method thereof. Background Technology

[0002] As the manufacturing industry demands increasingly sophisticated machining of complex parts, CNC turning-milling lathes are becoming more widely used in industrial production. These machine tools typically integrate turning and milling functions on the same machine. In automated machining processes, to achieve seamless integration of different operations, the machine tool needs to be equipped with an automatic tool changer.

[0003] Currently, existing tool changing mechanisms for lathes often suffer from unreasonable stroke layouts, frequently requiring the entire tool magazine or tool post to be moved a considerable distance to complete the docking, leading to increased tool changing assistance time and low efficiency. Some high-end models have attempted to introduce multi-axis robotic arms for tool changing, but due to the complex structure and heavy weight of various robotic arms, and to avoid affecting the machining accuracy of the lathe tools, they can only be fixedly mounted on the machine frame. When dealing with long-stroke tool changing tasks, not only are the equipment costs extremely high, but the motion logic is also cumbersome, resulting in unsatisfactory actual operating efficiency, making it difficult to meet the dual requirements of high cost-effectiveness and high production cycle time for mid-to-high-end machine tools. Summary of the Invention

[0004] To address the aforementioned shortcomings, the present invention aims to provide a tool changing mechanism and a CNC lathe using the same, along with its control method, thereby solving the problem of low efficiency in the tool changing mechanism of a milling-turning CNC lathe.

[0005] To achieve this objective, the present invention adopts the following technical solution: A turning tool changing mechanism includes a swing arm unit, a tool post unit, and a tool magazine unit. The swing arm unit and the tool post unit are disposed on the turning tool moving carriage of a CNC lathe, and the tool magazine unit is disposed on the fixed frame of the CNC lathe. The swing arm unit is located between the tool post unit and the tool magazine unit and is disposed close to the tool post unit. The tool holder unit includes a tool mounting assembly, which includes a tool holder, a tool mounting shaft, and a tool mounting sensor. The tool holder is connected to the tool moving frame. The tool mounting shaft is mounted on the tool holder, and its axis is set along the X direction. One end of the tool mounting shaft along the X direction is used to mount a tool, and the other end of the tool mounting shaft along the X direction extends out of the tool holder. The tool mounting sensor is located on the tool holder and near the end of the tool mounting shaft that extends out. The tool mounting shaft is movable along the X direction, and its movement along the X direction is used to lock and unlock the tool mounted on the tool mounting shaft. The tool mounting sensor is used to detect whether the tool mounting shaft is at the end of its travel along the X direction. The tool magazine unit is used to store lathe tools; The swing arm unit includes a rotary driver, a linear driver, and a gripper. The linear driver includes a housing, an arm shaft, and a piston. The housing is used to fix the tool moving frame of the CNC lathe. A closed straight cavity is provided inside the housing along the X direction. The arm shaft passes through the straight cavity, and the axis of the arm shaft is arranged along the X direction. One end of the arm shaft is connected to the piston, and the other end of the arm shaft is used to install the gripper. The gripper is used to grip the cutting tool. The rotary actuator is fixed to one end of the housing in the X direction. The housing has a first through hole along the X direction, which communicates with the straight cavity. The output end of the rotary actuator passes through the first through hole and is connected to the arm shaft. The rotary actuator is used to drive the arm shaft to rotate around the X direction. The swing arm unit also includes an arm shaft displacement sensor and a mounting cover. The outer shell is provided with a mounting port, which is located away from the straight cavity. The mounting cover covers the mounting port. The arm shaft displacement sensor is disposed in the mounting port. The detection direction of the arm shaft displacement sensor is radially directed towards the arm shaft. The outer periphery of the arm shaft is provided with an annular positioning groove. The arm shaft displacement sensor is used to detect the distance between the arm shaft displacement sensor and the outer side of the arm shaft.

[0006] Preferably, the arm shaft displacement sensor includes a first sensor and a second sensor, which are respectively disposed near the two ends of the mounting port along the X direction. When the arm shaft moves along the X-axis to the piston end to the end of its stroke, the annular positioning groove is located at the detection position of the first sensor. When the arm shaft moves along the X-axis to the gripper end to the end of its stroke, the annular positioning groove is located at the detection position of the second sensor.

[0007] Preferably, the piston divides the straight cavity into a first inner cavity and a second inner cavity, which are arranged opposite each other along the X direction. The outer shell is provided with a first air hole and a second air hole. The first air hole communicates with the first inner cavity, and the second air hole communicates with the second inner cavity. The first air hole and the second air hole are used to connect to an external driving air source. The piston is provided with sealing rings on both its inner and outer circumferences. The external driving air source is used to supply air to the first inner cavity or the second inner cavity to drive the piston to reciprocate along the X direction. The reciprocating movement of the piston is used to drive the arm shaft and the gripper to reciprocate along the X direction.

[0008] Preferably, the inner circumference of the piston and the outer circumference of the arm shaft are provided with matching ball mounting grooves, and a plurality of balls are embedded in the ball mounting grooves, the plurality of balls abutting between the arm shaft and the piston; The piston includes a collar, and the piston has a ball mounting through hole in the radial direction, the ball mounting through hole communicating with the ball mounting groove, the collar being sleeved on the outer periphery of the piston, the collar being used to close the ball mounting through hole.

[0009] Preferably, the tool magazine unit includes a rotary motor, a turntable, and a plurality of tool connectors. The rotary motor is mounted on the fixed frame of the CNC lathe, the turntable is mounted on the rotary output part of the rotary motor, the turntable is provided with a plurality of mounting holes, the plurality of mounting holes are equally spaced along the circumference of the turntable, and the plurality of tool connectors are respectively provided in the plurality of mounting holes, the tool connectors being used to install stored lathe tools.

[0010] Preferably, the rotating motor is a first servo motor with a first reducer, and the first servo motor is connected to the turntable through the first reducer.

[0011] Preferably, the rotary drive is a second servo motor with a second reducer, and the second servo motor is connected to the arm shaft through the second reducer.

[0012] Preferably, both the cutting tool mounting sensor and the arm shaft displacement sensor are laser rangefinders.

[0013] A CNC lathe includes a milling cutter unit, a workpiece clamping unit, a fixed frame, a milling cutter moving frame, a turning tool moving frame, a milling cutter moving unit, a turning tool moving unit, a control unit, and the aforementioned turning tool changing mechanism. The milling cutter unit is disposed on the milling cutter moving frame, and the workpiece clamping unit, the milling cutter moving frame, and the turning tool moving frame are all disposed on the fixed frame. The milling cutter moving frame and the turning tool moving frame are both located on the same side of the fixed frame, and the milling cutter unit is located on the side of the tool holder away from the swing arm unit. The workpiece clamping unit is used to clamp the workpiece, the milling cutter unit is equipped with a milling cutter driver, the milling cutter moving unit is used to drive the milling cutter moving frame to move the milling cutter unit closer to or away from the workpiece clamping unit, the milling cutter driver is used to drive the milling cutter to rotate, and the rotation of the milling cutter is used to mill the clamped workpiece. The workpiece clamping unit is also used to drive the workpiece to rotate. The tool mounting shaft of the tool changing mechanism is equipped with a cutting tool. The tool moving unit is used to drive the tool moving frame to move the tool changing mechanism and the cutting tool on it closer to or away from the workpiece clamping unit. The cutting tool is used to turn the clamped workpiece.

[0014] A control method for a lathe tool changing mechanism is provided, which controls the aforementioned lathe tool changing mechanism. The method includes preset numbers for each mounting hole in the tool magazine unit, the lathe tool model corresponding to each mounting hole number, the clamping position of the mounting hole, a first angle and a second angle of the rotary driver, and distance values ​​between a first sensor, a second sensor, and a lathe tool mounting sensor. The tool changing process includes the following steps: Obtain the model number of the cutting tool in use and the model number of the cutting tool to be replaced. Based on the model number of the cutting tool in use, control the rotating motor to rotate the corresponding numbered mounting hole to the clamping position of the mounting hole. Control the rotary driver to rotate to the first angle so that the gripper faces the tool mounting shaft side; The control tool mounting axis moves one end of the tool to unlock the tool. When the tool mounting sensor detects that the distance is less than the preset distance value, the tool moving component drives the chuck to approach the tool in use, so that the chuck clamps the tool in use. The linear drive arm moves axially to one end of the gripper. When the second sensor detects that the distance is greater than the preset distance value, the linear drive stops, causing the gripper to pull the cutting tool away from the cutting tool mounting shaft. Control the rotary driver to rotate to the second angle so that the gripper faces the tool magazine unit; The control tool moving component drives the chuck to approach the gripping position, so that the cutting tool in the chuck is directly opposite the tool joint; The linear actuator drives the arm to move axially to one end of the piston. When the first sensor detects that the distance is greater than the preset distance value, the linear actuator stops and the cutting tool is installed on the tool joint. The control tool moving component drives the jaws away from the gripping position, causing the jaws to release the cutting tool; The motor is controlled to rotate the corresponding numbered mounting hole to the tool magazine's clamping position according to the model of the cutting tool to be replaced. The control tool moving component drives the chuck to approach the tool located in the clamping position, so that the chuck clamps the tool to be replaced; The linear drive arm moves axially to one end of the gripper. When the second sensor detects that the distance is greater than the preset distance value, the linear drive stops, causing the gripper to pull the cutting tool away from the tool magazine unit. Control the rotary driver to rotate to the first angle so that the gripper faces the tool mounting shaft side; The control tool moving component drives the chuck to approach the tool mounting component, making the tool coaxial with the tool mounting axis; The linear actuator drives the arm to move axially towards one end of the piston. When the first sensor detects that the distance is greater than the preset distance value, the linear actuator stops, causing the cutting tool to press against the cutting tool mounting shaft. The cutting tool mounting shaft is then controlled to move axially towards one end of the cutting tool mounting sensor to lock the cutting tool. When the cutting tool mounting sensor detects that the distance is less than the preset distance value, the linear actuator stops. The linear actuator drives the arm to move axially to one end of the gripper. When the second sensor detects that the distance is greater than the preset distance value, the linear actuator stops, causing the gripper to leave the cutting tool. The rotary driver is controlled to rotate to the first angle, so that the gripper faces the tool magazine unit, thus completing the tool change.

[0015] The technical solution provided by this invention may include the following beneficial effects: 1. By integrating the rotary driver, linear driver, and gripper depth, and utilizing the piston's reciprocating motion along the X-direction within a closed straight cavity under pneumatic drive, the rotary driver directly drives the arm shaft rotation, achieving decoupled control of linear displacement and rotary motion. This significantly reduces the size and weight of the tool changing mechanism. In particular, the design of fixing the arm shaft displacement sensor within the housing mounting port, rather than having it move with the arm shaft, eliminates the need for clearance for the moving sensor and its wiring harness, making the overall structure more compact. This allows for further miniaturization and weight reduction of the swing arm unit, meeting the high space integration requirements of milling and turning machines. Simultaneously, the tool mounting sensor establishes a sensitive force feedback mechanism, ensuring the tool's positional accuracy during handover and contact. This sensing combination provides real-time, accurate physical quantity feedback to the control unit, enabling it to determine the status based on actual feedback data, rather than simply relying on program-set strokes, thus improving safety.

[0016] 2. By independently and fixedly installing the tool magazine unit, which carries a large number of cutting tools and has a large self-weight, on the fixed frame of the CNC lathe, and integrating the simplified and flexible swing arm unit and the tool post unit together into the cutting tool moving frame, a reasonable layout of "fixed for heavy loads and moving for light loads" is achieved. This improves the speed and efficiency of tool changing while reducing the impact of motion load on the machining accuracy of the cutting tools, and solves the problems of bulky structure, complex drive system, large space occupation, and low cutting tool changing efficiency of traditional tool changing mechanisms.

[0017] 3. A non-contact detection system is constructed by integrating a first and second sensor within the mounting cover and utilizing the annular positioning groove on the outer circumference of the arm shaft. This configuration identifies changes in the radial distance between the groove and the sensor, determining in real time whether the arm shaft has reached the end of its stroke, providing precise positioning feedback signals to the control system. Compared to traditional mechanical limit switches, this design not only avoids wear and accuracy degradation caused by physical contact but also utilizes a dual-sensor layout to achieve bidirectional monitoring of the initial tool change position and the working position, greatly improving the operational stability of the swing arm in complex machining environments.

[0018] 4. By controlling the pressure difference between the first and second inner chambers, the drive arm shaft achieves efficient reciprocating motion in the X direction. This integrated linear drive structure features faster power response and simpler maintenance costs. Combined with double sealing rings on the inner and outer circumferences of the piston, it ensures stable pneumatic pressure output and smooth connection of the motion trajectory.

[0019] 5. A ball bearing mounting groove and balls are embedded between the piston and the arm shaft, converting sliding friction into rolling friction. This improvement significantly reduces the resistance of the arm shaft during reciprocating movement, not only improving the sensitivity of the action but also reducing mechanical wear during long-term, frequent tool changes, thus extending the service life of core components.

[0020] 6. A rotating motor drives a turntable with equally spaced mounting holes to achieve circumferential array storage of turning tools in conjunction with the tool connector. This fixed installation method, independent of moving parts, allows the tool magazine unit to carry a large number and weight of turning tools without increasing the load on the tool moving frame. Combined with the rotation positioning function of the turntable, it ensures that each turning tool can accurately reach the preset clamping position during the tool changing process.

[0021] 7. A laser rangefinder is used as the core of the detection system, and the high linearity of the laser is used to achieve non-contact and precise monitoring of the displacement of the tool mounting axis and the arm axis.

[0022] 8. CNC lathes construct a highly integrated composite machining space by rationally arranging the milling cutter unit and turning tool changing mechanism, and utilizing lightweight swing arm units and tool post units for synchronous follow-up. This layout allows the workpiece to quickly switch between turning and milling modes in a single clamping, shortening the idle travel time of the tool between the tool magazine and the workpiece, and significantly improving the overall output efficiency and machining consistency of the CNC lathe.

[0023] 9. By setting a preset distance threshold, complex tool changing actions are transformed into a closed-loop command flow based on real-time sensor feedback, achieving full automation of the precise tool installation process. The system uses a tool installation sensor to determine whether the tool is installed correctly and a boom displacement sensor to determine the boom's stroke status, ensuring that each action is executed safely and greatly reducing the subsequent risks caused by tool changing errors. Attached Figure Description

[0024] Figure 1 This is a three-dimensional structural diagram of a CNC lathe according to an embodiment of the present invention.

[0025] Figure 2 for Figure 1 Enlarged view of point A in the middle.

[0026] Figure 3 This is a partial cross-sectional view of a swing arm unit according to an embodiment of the present invention.

[0027] Figure 4 This is a schematic diagram of the structure of a swing arm unit according to an embodiment of the present invention.

[0028] Figure 5 This is a three-dimensional structural diagram of a tool magazine unit according to an embodiment of the present invention.

[0029] The components include: swing arm unit 1, rotary driver 11, second reducer 111, second servo motor 112, linear driver 12, housing 121, first air hole 1211, second air hole 1212, first through hole 1213, arm shaft 122, annular positioning groove 1221, piston 123, ball bearing mounting through hole 1231, straight cavity 124, first inner cavity 1241, second inner cavity 1242, ball bearing mounting groove 125, collar 126, gripper 13, arm shaft displacement sensor 14, and first sensor. 141. Second sensor; 142. Mounting cover; 15. Tool holder unit; 2. Tool mounting assembly; 21. Tool fixing bracket; 211. Tool mounting shaft; 212. Tool mounting sensor; 213. Tool magazine unit; 3. Rotary motor; 31. First reducer; 311. First servo motor; 312. Turntable; 32. Mounting hole; 321. Tool connector; 33. Milling cutter unit; 81. Workpiece clamping unit; 82. Fixing bracket; 83. Milling cutter moving bracket; 84. Tool moving bracket; 85. Milling cutter moving unit; 86. Tool moving unit; 87. Detailed Implementation

[0030] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0031] In the description of this invention, it should be understood that the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for 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. Furthermore, features defined with "first" and "second" may explicitly or implicitly include one or more of these features, used to distinguish and describe features, without any order or emphasis.

[0032] In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0033] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0034] A turning tool changing mechanism includes a swing arm unit 1, a tool post unit 2, and a tool magazine unit 3. The swing arm unit 1 and the tool post unit 2 are disposed on the turning tool moving frame 85 of a CNC lathe, and the tool magazine unit 3 is disposed on the fixed frame 83 of the CNC lathe. The swing arm unit 1 is located between the tool post unit 2 and the tool magazine unit 3, and is disposed close to the tool post unit 2. The tool holder unit 2 includes a cutting tool mounting assembly 21, which includes a cutting tool fixing bracket 211, a cutting tool mounting shaft 212, and a cutting tool mounting sensor 213. The cutting tool fixing bracket 211 is connected to the cutting tool moving bracket 85. The cutting tool mounting shaft 212 is mounted on the cutting tool fixing bracket 211, and its axis is set along the X direction. One end of the cutting tool mounting shaft 212 along the X direction is used to mount a cutting tool, and the other end of the cutting tool mounting shaft 212 along the X direction... The tool mounting sensor 213 is disposed on the tool holder 211 and near the end of the tool mounting shaft 212 that protrudes from the tool holder 211. The tool mounting shaft 212 can move in the X direction. The movement of the tool mounting shaft 212 in the X direction is used to lock and unlock the tool mounted on the tool mounting shaft 212. The tool mounting sensor 213 is used to detect whether the tool mounting shaft 212 is at the end of the stroke of the tool mounting shaft 212 in the X direction. The tool magazine unit 3 is used to store lathe tools; The swing arm unit 1 includes a rotary driver 11, a linear driver 12, and a gripper 13. The linear driver 12 includes a housing 121, an arm shaft 122, and a piston 123. The housing 121 is used to fix the tool moving frame 85 of the CNC lathe. The housing 121 has a closed straight cavity 124 along the X direction. The arm shaft 122 passes through the straight cavity 124, and the axis of the arm shaft 122 is arranged along the X direction. One end of the arm shaft 122 is connected to the piston 123, and the other end of the arm shaft 122 is used to install the gripper 13. The gripper 13 is used to grip the cutting tool. The rotation driver 11 is fixed to one end of the housing 121 in the X direction. The housing 121 is provided with a first through hole 1213 in the X direction. The first through hole 1213 communicates with the straight cavity 124. The output end of the rotation driver 11 passes through the first through hole 1213 and is connected to the arm shaft 122. The rotation driver 11 is used to drive the arm shaft 122 to rotate around the X direction. The swing arm unit 1 further includes an arm shaft displacement sensor 14 and a mounting cover 15. The outer shell 121 is provided with a mounting port, which is located away from the straight cavity 124. The mounting cover 15 covers the mounting port. The arm shaft displacement sensor 14 is disposed in the mounting port. The detection direction of the arm shaft displacement sensor 14 is radially directed towards the arm shaft 122. The outer periphery of the arm shaft 122 is provided with an annular positioning groove 1221. The arm shaft displacement sensor 14 is used to detect the distance between the arm shaft displacement sensor 14 and the outer side of the arm shaft 122.

[0035] like Figure 1 , Figure 2 and Figure 3 As shown, by deeply integrating the rotary driver 11, linear driver 12, and gripper 13, and utilizing the piston 123's pneumatic drive to reciprocate along the X-direction within the enclosed straight cavity 124, the rotary driver 11 directly drives the arm shaft 122 to rotate, achieving decoupled control of linear displacement and rotational motion, significantly reducing the size and weight of the tool changing mechanism. In particular, the design of fixing the arm shaft displacement sensor 14 within the mounting opening of the housing 121, rather than having it move with the arm shaft 122, eliminates the need for clearance space reserved for the moving sensor and its wiring harness, making the overall structure more compact. This allows for further miniaturization and weight reduction of the swing arm unit 1, meeting the high spatial integration requirements of milling and turning composite machine tools. Simultaneously, the tool mounting sensor 213 establishes a sensitive force feedback mechanism, ensuring the accuracy of the tool's position during handover and contact. This sensing combination provides real-time and accurate physical quantity feedback to the control unit, enabling it to determine the status based on actual feedback data, rather than simply relying on program-set strokes, thus improving safety.

[0036] Furthermore, by independently and fixedly installing the tool magazine unit 3, which carries a large number of cutting tools and has a large self-weight, on the fixed frame 83 of the CNC lathe, and integrating the simplified and flexible swing arm unit 1 and the tool post unit 2 together on the cutting tool moving frame 85, a reasonable layout of "fixed for heavy loads and moving for light loads" is achieved. This improves the speed and efficiency of tool changing while reducing the impact of motion load on the machining accuracy of the cutting tools, and solves the problems of bulky structure, complex drive system, large space occupation, and low cutting tool changing efficiency of traditional tool changing mechanisms.

[0037] In a specific embodiment, the tool mounting shaft 212 has a movable joint at one end where the cutting tool is mounted. The tool mounting shaft 212 locks and unlocks the cutting tool through the movable joint. The movable joint contains a spring-supported ball, and one end of the cutting tool has a groove that matches the ball. The cutting tool is engaged in the movable joint through the groove and the ball. The tool mounting shaft 212 is controlled by the control unit of the CNC lathe to move along the X direction via an air source. When the tool mounting shaft 212 approaches the tool mounting sensor along the X direction and triggers the tool mounting sensor, the movable joint locks the cutting tool, completing the tool mounting and providing sufficient locking force for turning. When the tool mounting shaft 212 moves away from the tool mounting sensor along the X direction, the movable joint unlocks the cutting tool, and the cutting tool is fixed only by the groove and the ball, making it easy for the gripper 13 to pick up the cutting tool.

[0038] Preferably, the arm shaft displacement sensor 14 includes a first sensor 141 and a second sensor 142. The first sensor 141 and the second sensor 142 are respectively disposed near the two ends of the mounting port along the X direction. When the arm shaft 122 moves along the X-axis to the end of the piston 123, the annular positioning groove 1221 is located at the detection position of the first sensor 141. When the arm shaft 122 moves along the X-axis to the end of the gripper 13, the annular positioning groove 1221 is located at the detection position of the second sensor 142.

[0039] A non-contact detection system is constructed by integrating a first sensor 141 and a second sensor 142 within the mounting cover 15 and utilizing the annular positioning groove 1221 on the outer periphery of the arm shaft 122. This configuration determines in real time whether the arm shaft 122 has reached the end of its stroke by identifying changes in the radial distance between the groove and the sensor, providing precise positioning feedback signals to the control system. Compared to traditional mechanical limit switches, this design not only avoids wear and accuracy degradation caused by physical contact but also utilizes a dual-sensor layout to achieve bidirectional monitoring of the tool change initial position and the working position, greatly improving the operational stability of the swing arm in complex machining environments.

[0040] Preferably, the piston 123 divides the straight cavity 124 into a first inner cavity 1241 and a second inner cavity 1242. The first inner cavity 1241 and the second inner cavity 1242 are arranged opposite each other along the X direction. The outer shell 121 is provided with a first air hole 1211 and a second air hole 1212. The first air hole 1211 is connected to the first inner cavity 1241, and the second air hole 1212 is connected to the second inner cavity 1242. The first air hole 1211 and the second air hole 1212 are used to connect to an external driving air source. The piston 123 is provided with sealing rings on both its inner and outer circumferences. The external driving air source is used to supply air to the first inner cavity 1241 or the second inner cavity 1242 to drive the piston 123 to reciprocate along the X direction. The reciprocating movement of the piston 123 is used to drive the arm shaft 122 and the gripper 13 to reciprocate along the X direction.

[0041] like Figure 3 and Figure 4 As shown, the linear actuator 12 adopts a pneumatically driven piston 123-type straight-cavity 124 structure. Through pressure difference control between the first inner cavity 1241 and the second inner cavity 1242, the drive arm shaft 122 achieves efficient reciprocating motion in the X direction. This integrated linear drive structure features faster power response and simpler maintenance costs. Combined with the double sealing rings on the inner and outer circumferences of the piston 123, it ensures stable pneumatic pressure output and smooth connection of the motion trajectory.

[0042] Preferably, the inner circumference of the piston 123 and the outer circumference of the arm shaft 122 are provided with matching ball mounting grooves 125, and a plurality of balls are embedded in the ball mounting grooves 125, and the plurality of balls abut against the arm shaft 122 and the piston 123. The piston 123 includes a collar 126. The piston 123 has a ball mounting through hole 1231 arranged radially. The ball mounting through hole 1231 communicates with the ball mounting groove 125. The collar 126 is sleeved on the outer periphery of the piston 123 and is used to close the ball mounting through hole 1231.

[0043] A ball bearing mounting groove 125 and a ball bearing are embedded between the piston 123 and the arm shaft 122, converting sliding friction into rolling friction. This improvement significantly reduces the resistance of the arm shaft 122 during reciprocating movement, not only improving the sensitivity of the movement but also reducing mechanical wear during long-term and frequent tool changes, thus extending the service life of the core components.

[0044] Preferably, the tool magazine unit 3 includes a rotary motor 31, a turntable 32, and a plurality of tool connectors 33. The rotary motor 31 is mounted on the fixed frame 83 of the CNC lathe. The turntable 32 is mounted on the rotation output part of the rotary motor 31. The turntable 32 is provided with a plurality of mounting holes 321, which are equally spaced along the circumference of the turntable 32. The plurality of tool connectors 33 are respectively and correspondingly provided in the plurality of mounting holes 321. The tool connectors 33 are used to install stored lathe tools.

[0045] like Figure 5 As shown, the rotary motor 31 drives the turntable 32 with equally spaced mounting holes 321, which, together with the tool connector 33, realizes the circumferential array storage of turning tools. This fixed installation method, independent of moving parts, allows the tool magazine unit 3 to carry a large number and weight of turning tools without increasing the load on the turning tool moving frame 85. Combined with the rotation positioning function of the turntable 32, it ensures that each turning tool can accurately reach the preset clamping position during the tool changing process.

[0046] In a specific embodiment, the tool connector 33 is provided with a spring-supported ball, and one end of the cutting tool is provided with a groove that matches the ball. The cutting tool is engaged with the tool connector through the groove and the ball.

[0047] Preferably, the rotating motor 31 is a first servo motor 312 with a first reducer 311, and the first servo motor 312 is connected to the turntable 32 through the first reducer 311.

[0048] Preferably, the rotary driver 11 is a second servo motor 112 with a second reducer 111, and the second servo motor 112 is connected to the arm shaft 122 through the second reducer 111.

[0049] By configuring both the rotary motor 31 and the rotary driver 11 as servo motors and equipping them with reducers, extremely high rotational control precision and torque output stability are achieved. The precise control capability of the servo motor ensures smooth start and stop and controlled positioning of the rotational movements of the turntable 32 and the arm shaft 122, while the introduction of the reducer provides sufficient locking torque while reducing the size of the motor, further improving rotational accuracy.

[0050] Preferably, both the cutting tool mounting sensor 213 and the arm shaft displacement sensor 14 are laser rangefinders.

[0051] A laser rangefinder is used as the core of the detection system, and the high linearity of the laser is used to achieve non-contact and precise monitoring of the displacement of the tool mounting shaft 212 and the arm shaft 122.

[0052] A CNC lathe includes a milling cutter unit 81, a workpiece clamping unit 82, a fixed frame 83, a milling cutter moving frame 84, a turning tool moving frame 85, a milling cutter moving unit 86, a turning tool moving unit 87, a control unit, and the aforementioned turning tool changing mechanism. The milling cutter unit 81 is disposed on the milling cutter moving frame 84. The workpiece clamping unit 82, the milling cutter moving frame 84, and the turning tool moving frame 85 are all disposed on the fixed frame 83. The milling cutter moving frame 84 and the turning tool moving frame 85 are both located on the same side of the fixed frame 83, and the milling cutter unit 81 is located on the side of the tool holder away from the swing arm unit 1. The workpiece clamping unit 82 is used to clamp the workpiece, the milling cutter unit 81 is provided with a milling cutter driver, the milling cutter moving unit 86 is used to drive the milling cutter moving frame 84 to move the milling cutter unit 81 closer to or away from the workpiece clamping unit 82, the milling cutter driver is used to drive the milling cutter to rotate, and the rotation of the milling cutter is used to mill the clamped workpiece. The workpiece clamping unit 82 is also used to drive the workpiece to rotate. The cutting tool mounting shaft 212 of the cutting tool changing mechanism is equipped with a cutting tool. The cutting tool moving unit 87 is used to drive the cutting tool moving frame 85 to move the cutting tool changing mechanism and the cutting tool on it closer to or away from the workpiece clamping unit 82. The cutting tool is used to turn the clamped workpiece.

[0053] The CNC lathe constructs a highly integrated composite machining space by rationally arranging the milling cutter unit 81 and the turning tool changing mechanism, and utilizing the lightweight swing arm unit 1 and the tool post unit 2 for synchronous follow-up. This layout allows the workpiece to quickly switch between turning and milling modes in a single clamping, shortening the idle travel time of the tool between the tool magazine and the workpiece, and significantly improving the overall output efficiency and machining consistency of the CNC lathe.

[0054] A control method for a lathe tool changing mechanism is provided for controlling the aforementioned lathe tool changing mechanism. The method includes preset numbers for each mounting hole 321 in the tool magazine unit 3, the lathe tool model corresponding to each mounting hole 321 number, the clamping position of the mounting hole 321, a first angle and a second angle of the rotation driver 11, and distance values ​​between a first sensor 141, a second sensor 142, and a lathe tool mounting sensor 213. The tool changing process includes the following steps: Obtain the model of the cutting tool in use and the model of the cutting tool to be replaced. Control the rotating motor 31 to rotate the corresponding numbered mounting hole 321 to the clamping position of the mounting hole 321 according to the model of the cutting tool in use. Control the rotary driver 11 to rotate to the first angle, so that the jaw 13 faces the tool mounting shaft 212 side; The control tool mounting shaft 212 moves towards the tool mounting end to unlock the tool. The tool mounting sensor 213 detects that the distance is less than the preset distance value. The tool moving component drives the chuck 13 to approach the tool in use, so that the chuck 13 clamps the tool in use. The linear driver 12 drives the arm shaft 122 to move towards one end of the gripper 13. When the second sensor 142 detects that the distance is greater than the preset distance value, the linear driver 12 stops, causing the gripper 13 to drive the cutting tool away from the cutting tool mounting shaft 212. Control the rotation driver 11 to rotate to the second angle, so that the gripper 13 faces the tool magazine unit 3; The control tool moving component drives the chuck 13 to approach the gripping position, so that the cutting tool in the chuck 13 is directly opposite the tool connector 33; The linear actuator 12 drives the arm shaft 122 to move toward one end of the piston 123. After the first sensor 141 detects that the distance is greater than the preset distance value, the linear actuator 12 stops and the cutting tool is installed on the tool connector 33. The control tool moving component drives the chuck 13 away from the clamping position, so that the chuck 13 releases the cutting tool; According to the model of the cutting tool to be replaced, control the rotating motor 31 to rotate the corresponding numbered mounting hole 321 to the clamping position of the tool magazine; The control tool moving component drives the chuck 13 to approach the tool located in the clamping position, so that the chuck 13 clamps the tool to be replaced; The linear actuator 12 drives the arm shaft 122 to move towards one end of the gripper 13. When the second sensor 142 detects that the distance is greater than the preset distance value, the linear actuator 12 stops, causing the gripper 13 to drive the cutting tool away from the tool magazine unit 3. Control the rotary driver 11 to rotate to the first angle, so that the jaw 13 faces the tool mounting shaft 212 side; The control tool moving component drives the gripper 13 to approach the tool mounting component 21, so that the tool and the tool mounting shaft 212 are coaxial; The linear actuator 12 drives the arm shaft 122 to move toward the piston 123. After the first sensor 141 detects that the distance is greater than the preset distance value, the linear actuator 12 stops, causing the cutting tool to abut against the cutting tool mounting shaft 212. The cutting tool mounting shaft 212 is then controlled to move toward the end closer to the cutting tool mounting sensor 213 to lock the cutting tool. The cutting tool mounting sensor 213 detects that the distance is less than the preset distance value. The linear driver 12 drives the arm shaft 122 to move towards one end of the gripper 13. When the second sensor 142 detects that the distance is greater than the preset distance value, the linear driver 12 stops, causing the gripper 13 to leave the cutting tool. The rotary driver 11 is controlled to rotate to the first angle, so that the gripper 13 faces the tool magazine unit 3, thus completing the tool change.

[0055] In a specific embodiment, different types of cutting tools are manually installed on each tool connector 33, and the cutting tool model and number are input into the control unit accordingly.

[0056] By setting a preset distance threshold, the complex tool changing action is transformed into a closed-loop command flow based on real-time sensor feedback, achieving full automation of the precise tool installation process. The system uses the tool installation sensor 213 to determine whether the tool is installed correctly and the arm shaft displacement sensor 14 to determine the stroke status of the arm shaft 122, ensuring that each action is executed safely and greatly reducing the subsequent risks caused by tool changing errors.

[0057] In a specific embodiment, when the locking or unlocking process of the cutting tool in use is stuck, causing a program error, the cutting tool mounting axis 212 is not in the correct displacement stroke. The cutting tool mounting sensor 213 detects that the distance is different from the preset program, and the control unit immediately controls the CNC lathe to stop and wait for manual intervention to restore it.

[0058] Other configurations and operations according to embodiments of the present invention are known to those skilled in the art and will not be described in detail here.

[0059] In the description of this specification, references to terms such as "embodiment," "example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0060] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A tool changing mechanism for lathes, characterized in that: It includes a swing arm unit, a tool post unit, and a tool magazine unit. The swing arm unit and the tool post unit are disposed on the tool moving carriage of the CNC lathe, and the tool magazine unit is disposed on the fixed frame of the CNC lathe. The swing arm unit is located between the tool post unit and the tool magazine unit and is disposed close to the tool post unit. The tool holder unit includes a tool mounting assembly, which includes a tool holder, a tool mounting shaft, and a tool mounting sensor. The tool holder is connected to the tool moving frame. The tool mounting shaft is mounted on the tool holder, and its axis is set along the X direction. One end of the tool mounting shaft along the X direction is used to mount a tool, and the other end of the tool mounting shaft along the X direction extends out of the tool holder. The tool mounting sensor is located on the tool holder and near the end of the tool mounting shaft that extends out. The tool mounting shaft is movable along the X direction, and its movement along the X direction is used to lock and unlock the tool mounted on the tool mounting shaft. The tool mounting sensor is used to detect whether the tool mounting shaft is at the end of its travel along the X direction. The tool magazine unit is used to store lathe tools; The swing arm unit includes a rotary driver, a linear driver, and a gripper. The linear driver includes a housing, an arm shaft, and a piston. The housing is used to fix the tool moving frame of the CNC lathe. A closed straight cavity is provided inside the housing along the X direction. The arm shaft passes through the straight cavity, and the axis of the arm shaft is arranged along the X direction. One end of the arm shaft is connected to the piston, and the other end of the arm shaft is used to install the gripper. The gripper is used to grip the cutting tool. The rotary actuator is fixed to one end of the housing in the X direction. The housing has a first through hole along the X direction, which communicates with the straight cavity. The output end of the rotary actuator passes through the first through hole and is connected to the arm shaft. The rotary actuator is used to drive the arm shaft to rotate around the X direction. The swing arm unit also includes an arm shaft displacement sensor and a mounting cover. The outer shell is provided with a mounting port, which is located away from the straight cavity. The mounting cover covers the mounting port. The arm shaft displacement sensor is disposed in the mounting port. The detection direction of the arm shaft displacement sensor is radially directed towards the arm shaft. The outer periphery of the arm shaft is provided with an annular positioning groove. The arm shaft displacement sensor is used to detect the distance between the arm shaft displacement sensor and the outer side of the arm shaft.

2. The tool changing mechanism for lathes according to claim 1, characterized in that: The arm shaft displacement sensor includes a first sensor and a second sensor. The first sensor and the second sensor are respectively disposed near the two ends of the mounting port along the X direction. When the arm shaft moves along the X-axis to the piston end to the end of its stroke, the annular positioning groove is located at the detection position of the first sensor. When the arm shaft moves along the X-axis to the jaw end to the end of its stroke, the annular positioning groove is located at the detection position of the second sensor.

3. The tool changing mechanism for lathes according to claim 1, characterized in that: The piston divides the straight cavity into a first inner cavity and a second inner cavity, which are arranged opposite each other along the X direction. The outer shell is provided with a first air hole and a second air hole. The first air hole is connected to the first inner cavity, and the second air hole is connected to the second inner cavity. The first air hole and the second air hole are used to connect to an external driving air source. The piston is provided with sealing rings on both its inner and outer circumferences. The external driving air source is used to supply air to the first inner cavity or the second inner cavity to drive the piston to reciprocate along the X direction. The reciprocating movement of the piston is used to drive the arm shaft and the gripper to reciprocate along the X direction.

4. The tool changing mechanism for lathes according to claim 1, characterized in that: The inner circumference of the piston and the outer circumference of the arm shaft are provided with matching ball mounting grooves, and a plurality of balls are embedded in the ball mounting grooves, with the plurality of balls abutting between the arm shaft and the piston. The piston includes a collar, and the piston has a ball mounting through hole in the radial direction, the ball mounting through hole communicating with the ball mounting groove, the collar being sleeved on the outer periphery of the piston, the collar being used to close the ball mounting through hole.

5. A tool changing mechanism for lathes according to claim 1, characterized in that: The tool magazine unit includes a rotary motor, a turntable, and several tool connectors. The rotary motor is mounted on the fixed frame of the CNC lathe. The turntable is mounted on the rotary output part of the rotary motor. The turntable has several mounting holes, which are evenly spaced along the circumference of the turntable. The tool connectors are respectively and correspondingly mounted in the mounting holes. The tool connectors are used to install stored lathe tools.

6. A tool changing mechanism for lathes according to claim 5, characterized in that: The rotating motor is a first servo motor with a first reducer, and the first servo motor is connected to the turntable through the first reducer.

7. A tool changing mechanism for lathes according to claim 1, characterized in that: The rotary drive is a second servo motor with a second reducer, and the second servo motor is connected to the arm shaft through the second reducer.

8. A tool changing mechanism for lathes according to claim 1, characterized in that: Both the tool mounting sensor and the arm shaft displacement sensor are laser rangefinders.

9. A CNC lathe, characterized in that: The device includes a milling cutter unit, a workpiece clamping unit, a fixed frame, a milling cutter moving frame, a turning tool moving frame, a milling cutter moving unit, a turning tool moving unit, a control unit, and a turning tool changing mechanism as described in any one of claims 1-8. The milling cutter unit is disposed on the milling cutter moving frame, and the workpiece clamping unit, the milling cutter moving frame, and the turning tool moving frame are all disposed on the fixed frame. The milling cutter moving frame and the turning tool moving frame are both located on the same side of the fixed frame, and the milling cutter unit is located on the side of the tool holder away from the swing arm unit. The workpiece clamping unit is used to clamp the workpiece, the milling cutter unit is equipped with a milling cutter driver, the milling cutter moving unit is used to drive the milling cutter moving frame to move the milling cutter unit closer to or away from the workpiece clamping unit, the milling cutter driver is used to drive the milling cutter to rotate, and the rotation of the milling cutter is used to mill the clamped workpiece. The workpiece clamping unit is also used to drive the workpiece to rotate. The tool mounting shaft of the tool changing mechanism is equipped with a cutting tool. The tool moving unit is used to drive the tool moving frame to move the tool changing mechanism and the cutting tool on it closer to or away from the workpiece clamping unit. The cutting tool is used to turn the clamped workpiece.

10. A control method for a cutting tool changing mechanism, characterized in that: For controlling the tool changing mechanism according to any one of claims 1-8, the mechanism is pre-set with a number for each mounting hole in the tool magazine unit, a tool model corresponding to each mounting hole number, a clamping position of the mounting hole, a first angle and a second angle of the rotary driver, and distance values ​​between a first sensor, a second sensor, and a tool mounting sensor. The tool changing includes the following steps: Obtain the model number of the cutting tool in use and the model number of the cutting tool to be replaced. Based on the model number of the cutting tool in use, control the rotating motor to rotate the corresponding numbered mounting hole to the clamping position of the mounting hole. Control the rotary driver to rotate to the first angle so that the gripper faces the tool mounting shaft side; The control tool mounting axis moves one end of the tool to unlock the tool. When the tool mounting sensor detects that the distance is less than the preset distance value, the tool moving component drives the chuck to approach the tool in use, so that the chuck clamps the tool in use. The linear drive arm moves axially to one end of the gripper. When the second sensor detects that the distance is greater than the preset distance value, the linear drive stops, causing the gripper to pull the cutting tool away from the cutting tool mounting shaft. Control the rotary driver to rotate to the second angle so that the gripper faces the tool magazine unit; The control tool moving component drives the chuck to approach the gripping position, so that the cutting tool in the chuck is directly opposite the tool joint; The linear actuator drives the arm to move axially to one end of the piston. When the first sensor detects that the distance is greater than the preset distance value, the linear actuator stops and the cutting tool is installed on the tool joint. The control tool moving component drives the jaws away from the gripping position, causing the jaws to release the cutting tool; The motor is controlled to rotate the corresponding numbered mounting hole to the tool magazine's clamping position according to the model of the cutting tool to be replaced. The control tool moving component drives the chuck to approach the tool located in the clamping position, so that the chuck clamps the tool to be replaced; The linear drive arm moves axially to one end of the gripper. When the second sensor detects that the distance is greater than the preset distance value, the linear drive stops, causing the gripper to pull the cutting tool away from the tool magazine unit. Control the rotary driver to rotate to the first angle so that the gripper faces the tool mounting shaft side; The control tool moving component drives the gripper to approach the tool mounting component, making the tool coaxial with the tool mounting axis; The linear actuator drives the arm to move axially towards one end of the piston. When the first sensor detects that the distance is greater than the preset distance value, the linear actuator stops, causing the cutting tool to press against the cutting tool mounting shaft. The cutting tool mounting shaft is then controlled to move axially towards one end of the cutting tool mounting sensor to lock the cutting tool. When the cutting tool mounting sensor detects that the distance is less than the preset distance value, the linear actuator stops. The linear actuator drives the arm to move axially to one end of the gripper. When the second sensor detects that the distance is greater than the preset distance value, the linear actuator stops, causing the gripper to leave the cutting tool. The rotary driver is controlled to rotate to the first angle, so that the gripper faces the tool magazine unit, thus completing the tool change.

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