A welding robot joint based on differential cable drive

Abstract

This invention discloses a welding robot joint based on differential cable drive, belonging to the field of industrial robot technology. It includes a base frame, a first drive device, a differential cable drive device, a second drive device, a rotary transmission assembly, a movable joint, and a protective shell. One end of the protective shell is fixedly mounted on the base frame, one end of the rotary transmission assembly is fixedly mounted on the protective shell, and the other end is fixedly mounted on the movable joint. The differential cable drive device, the first drive device, and the second drive device are sequentially connected to the protective shell. This invention features a compact overall structure, ensuring the joint's output performance. It is suitable for specific welding robot arms, meets the welding requirements of special confined spaces, achieves precise control of the joint disc at minute angles, and improves welding accuracy. It simplifies the control algorithm, achieves decoupled control of two degrees of freedom, and improves motion accuracy.

Description

Technical Field

[0001] This invention relates to the field of industrial robot technology, and in particular to a welding robot joint based on differential cable drive. Background Technology

[0002] In fields with critical national needs, such as aerospace and rail transportation, welding robots are crucial equipment for ensuring the precision and efficiency of component manufacturing. Components in these fields require high-quality welding under complex conditions, and mass production demands stringent operational stability. However, confined spaces such as enclosed chambers and gaps between components make conventional welding robots unsuitable, necessitating specialized models adapted for these scenarios. The arm joint, as a core component of the welding robot, directly determines the equipment's compactness and high-precision transmission capabilities, making it key to enabling operations in confined spaces.

[0003] Currently, most traditional welding robot arms adopt a serial configuration, primarily using rotary joints. These joints employ a modular structure with servo motors, high-precision reducers, precision supports, and closed-loop detection. Heavy-duty joints commonly use RV reducers, while high-precision attitude adjustment joints preferentially use harmonic reducers. The joints are arranged in a serial configuration of base-shoulder-elbow-wrist to achieve their corresponding functions, forming a mature technological system. However, in welding operations in special confined spaces, existing welding robots struggle to achieve ideal welding results due to the challenge of balancing rigidity and flexibility. Furthermore, the traditional serial joint structure has reached a bottleneck in the coordinated optimization of spatial compactness and transmission accuracy. Existing structural solutions for this specific scenario also suffer from complex control and unstable accuracy. Therefore, developing a novel welding robot arm joint structure to overcome existing technological limitations and meet the demands of high-quality welding in confined spaces has become an urgent technical problem for the industry. Summary of the Invention

[0004] The purpose of this invention is to overcome the limitations of the prior art and provide a welding robot joint based on differential rope drive, which effectively solves the technical problems of redundant joint volume and difficult control decoupling in existing welding robot arms, realizes precise control of small angles, and adapts to the operation requirements of high-quality welding in confined spaces.

[0005] A welding robot joint based on differential rope drive includes a base frame, a first drive device, a differential rope drive device, a second drive device, a rotary transmission assembly, a movable joint, and a protective shell; wherein, one end of the protective shell is fixedly mounted on the base frame, one end of the rotary transmission assembly is fixedly mounted on the protective shell, and the other end is fixedly mounted on the movable joint, and the differential rope drive device, the first drive device, and the second drive device are sequentially connected and mounted inside the protective shell.

[0006] The base frame includes a motor end cover, a pulley end cover, and a base frame housing;

[0007] The first drive device includes a first motor, a first coupling, a first bearing, and a planetary roller screw;

[0008] The differential rope drive device includes a second bearing, a rotating ring, a retractable conical screw, an expanding conical screw, and a metal rope;

[0009] The second drive device includes a second motor, a second coupling, a short shaft, a drive pulley, a driven pulley, a transmission belt, a semi-circular tube, a rectangular platform, and a side plate;

[0010] The rotary transmission assembly includes a telescopic fixed rod, a grooved fixed ring, and a rotating rod; the movable joint includes a ball joint and a disc joint.

[0011] The motor end cover is fixedly connected to the pulley end cover, and the motor end cover and the pulley end cover are fixedly installed inside the base frame housing; the first motor and the second motor are fixedly installed on the motor end cover of the base frame;

[0012] The first motor is connected to the lead screw shaft of the planetary roller screw via a first coupling, and a nut is fitted onto the lead screw shaft;

[0013] The rotating ring is connected to the outer ring of the nut through the second bearing. The contraction type tapered screw and the expansion type tapered screw are symmetrically fixed and sleeved on both sides of the rotating ring through the third bearing. The two tapered screws have the same direction of rotation and opposite taper directions. The metal rope has a smooth surface and is a closed loop. The metal rope is wrapped around the contraction type tapered screw and the expansion type tapered screw. One side of the metal rope is set in the slide inside the disc joint, and the other side is set in the semi-circular tube of the rectangular platform on the surface of the driven pulley.

[0014] The output shaft of the second motor is connected to the second coupling, and the other end of the second coupling is connected to the short shaft. The driving pulley is connected to the short shaft and the second coupling. A rectangular platform is provided on the leading edge of one side surface of the driven pulley, and a side plate is provided in front of the rectangular platform. The driven pulley is driven by the driving pulley through the transmission belt. The driven pulley is mounted on the end cover of the pulley through the first bearing and can rotate freely.

[0015] The retractable fixing rod includes a shell and a built-in retractable rod, which is hinged to a disc joint. One end of the shell is fixed to the front edge side plate of the driven pulley, and the other end is fixedly connected to a grooved fixing ring. A rotating ring passes through the middle. The built-in retractable rod is fixedly connected to the disc joint. The grooved fixing ring is coaxially fixedly fitted with the protective shell. The rotating rod can rotate around the groove on the grooved fixing ring. The driven pulley is connected to the rotating ring, the rotating rod, and the disc joint through the retractable fixing rod.

[0016] The rotary transmission assembly's rotating rod is coaxially connected to the planetary roller screw, which is fixedly sleeved within the differential rope drive device. One end of the metal rope is movably mounted on the movable joint, and the other end is movably mounted on the driven pulley of the second drive device. One end of the telescopic fixed rod is connected to the driven pulley, and the other end is connected to the disc joint of the movable joint.

[0017] The disc joint is fixedly mounted on the ball joint, and a slide is provided on the inner side of the disc joint to guide the metal rope; the bottom of the ball joint is fixedly connected to the swivel rod.

[0018] The working process and working principle of this invention:

[0019] When the first motor is working, it drives the planetary roller screw shaft to rotate, causing the nut to move back and forth along the axial direction. The nut drives the rotating ring and the contraction type conical screw and expansion type conical screw to translate together. Then, through the differential winding and unwinding of the two metal ropes in the differential rope drive device, the disc joint is pulled to deflect around the center of the ball joint, realizing the swing freedom movement.

[0020] The contraction-type and expansion-type tapered screws are mounted on the rotating ring via a third bearing. A metal rope is wound around the two tapered screws on the rotating ring with the same initial winding length. Translation of the rotating ring forces the metal rope to simultaneously wind or unwind on both screws. Because the two screws have opposite tapers, the same linear displacement of the nut causes a corresponding change in the winding length of the metal rope on both screws, creating a differential effect of winding and unwinding. This causes the disc joint to deflect around the center of the ball joint, enabling multi-angle oscillating motion.

[0021] When the second motor is working, it drives the driven pulley to rotate via a belt drive structure. The driven pulley drives the rotating ring, the rotating rod, and the disc joint to rotate synchronously via a telescopic fixed rod, achieving rotational motion. The rotating ring drives the contractile and expansion conical screws to revolve together around the axis of the screw shaft, pulling the disc joint to rotate around the axis of the screw shaft, achieving rotational freedom of motion. The driving pulley, driven pulley, and transmission belt form a belt drive structure, with the driven pulley driven by the driving pulley via the transmission belt.

[0022] The telescopic fixed rod simultaneously drives the rotating ring and the swivel rod to rotate around the axis of the lead screw shaft. Correspondingly, the rotating ring drives the contracting conical lead screw and the expanding conical lead screw to revolve around the axis of the lead screw shaft, thereby pulling the metal rope to revolve around the axis of the lead screw shaft, ensuring that no interference occurs during the rotation process.

[0023] The telescopic fixed rod can extend and retract to accommodate the movement of the disc joint as it swings.

[0024] Planetary roller screws are high-rigidity, high-load, and high-precision transmission components.

[0025] The beneficial effects of this invention are:

[0026] The invention has a compact overall structure and nests the transmission chains of two degrees of freedom through a coaxial design, making it suitable for specific welding robot arms and meeting the welding needs of special confined spaces.

[0027] This invention uses two conical lead screws with opposite tapers to achieve differential rope drive, enabling precise control of the joint disc at minute angles and improving welding accuracy;

[0028] This invention uses a planetary roller screw as the main driving component, which has the advantages of high rigidity, high load capacity, and high precision, thus ensuring the output performance of the joint.

[0029] The control of the first driving device and the second driving device of the present invention is independent of each other, and their movements do not interfere with each other. This simplifies the control algorithm, realizes two-degree-of-freedom decoupled control, and improves motion accuracy. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention;

[0031] Figure 2 This is a structural disassembly diagram of an embodiment of the present invention;

[0032] Figure 3 This is a magnified schematic diagram of a portion of the structure of part A in an embodiment of the present invention;

[0033] Figure 4 This is a schematic diagram of the movable joint in an embodiment of the present invention;

[0034] Figure 5 This is a schematic diagram of the inner angle of the movable joint in an embodiment of the present invention;

[0035] Figure 6 This is an overall sectional view of an embodiment of the present invention;

[0036] Figure 7 This is a schematic diagram illustrating the usage state of the metal rope according to an embodiment of the present invention.

[0037] The diagram shows: 1. Base frame; 2. First drive unit. 5. Rotary transmission assembly; 6. Movable joint; 7. Protective shell; 11. Motor end cover; 12. Pulley end cover; 13. Base frame shell; 21. First motor; 22. First coupling; 23. First bearing; 24. Planetary roller screw; 241. Screw shaft; 242. Nut; 31. Second bearing; 32. Rotary ring; 33. Retractable tapered screw; 34. Expanding tapered screw; 35. Metal rope; 36. Third bearing; 41. Second motor; 42. Second coupling; 43. Short shaft; 44. Driving pulley; 45. Driven pulley; 46. Transmission belt; 47. Semicircular tube; 48. Rectangular platform; 49. Side plate; 51. Telescopic fixed rod; 511. Built-in telescopic rod; 512. Shell; 52. Grooved fixed ring; 53. Rotary rod; 61. Ball joint; 62. Disc joint. Detailed Implementation

[0038] Please see Figures 1 to 7 The image shown is an embodiment of the present invention.

[0039] A welding robot joint based on differential rope drive includes a base frame 1, a first drive device 2, a differential rope drive device, a second drive device, a rotary transmission assembly 5, a movable joint 6, and a protective shell 7. One end of the protective shell 7 is fixedly mounted on the base frame 1, one end of the rotary transmission assembly 5 is fixedly mounted on the protective shell 7, and the other end is fixedly mounted on the movable joint 6. The differential rope drive device, the first drive device 2, and the second drive device are sequentially connected and mounted inside the protective shell 7.

[0040] The base frame 1 includes a motor end cover 11, a pulley end cover 12, and a base frame housing 13; the base frame 1 is used to mount the entire joint onto the robot arm or base.

[0041] The first drive device 2 includes a first motor 21, a first coupling 22, a first bearing 23, and a planetary roller screw 24. The first motor 21 is fixed to the motor end cover 11 by bolts, and its output shaft is directly connected to the screw shaft 241 of the planetary roller screw 24 through the first coupling 22. The nut 242 of the planetary roller screw 24 is axially movable.

[0042] The differential rope drive device includes a second bearing 31, a rotating ring 32, a retractable conical screw 33, an expanding conical screw 34, and a metal rope 35.

[0043] The second drive device includes a second motor 41, a second coupling 42, a short shaft 43, a driving pulley 44, a driven pulley 45, a transmission belt 46, a semi-circular tube 47, a rectangular platform 48, and a side plate 49.

[0044] The rotary transmission assembly 5 includes a telescopic fixed rod 51, a grooved fixed ring 52, and a rotating rod 53.

[0045] The movable joint 6 includes a ball-head joint 61 and a disc joint 62.

[0046] The motor end cover 11 is fixedly connected to the pulley end cover 12, and the motor end cover 11 and the pulley end cover 12 are fixedly installed inside the base frame housing 13; the first motor 21 and the second motor 41 are fixedly installed on the motor end cover 11 of the base frame 1.

[0047] The first motor 21 is connected to the lead screw shaft 241 of the planetary roller screw 24 via the first coupling 22, and the nut 242 is fitted onto the lead screw shaft 241.

[0048] The rotating ring 32 is connected to the outer ring of the nut 242 of the planetary roller screw 24 via the second bearing 31. The contraction type tapered screw 33 and the expansion type tapered screw 34 are symmetrically fixed and sleeved on both sides of the rotating ring 32 via the third bearing 36. The two tapered screws have the same direction of rotation and opposite taper directions. The metal rope 35 has a smooth surface and is a closed loop. The metal rope 35 is wrapped around the contraction type tapered screw 33 and the expansion type tapered screw 34. It has low friction and can slide freely. One side of the metal rope 35 is set in the slide rail inside the disc joint 62, and the other side is set in the semi-circular tube 47 of the rectangular platform on the surface of the driven pulley 45.

[0049] The second motor 41 is bolted to the motor end cover 11. The output shaft of the second motor 41 is connected to the second coupling 42, and the other end of the second coupling 42 is connected to the short shaft 43. The driving pulley 44 is connected to the second coupling 42 via the short shaft 43. A rectangular platform 48 is provided on the leading edge of one side surface of the driven pulley 45, and a side plate 49 is provided in front of the rectangular platform 48. The driving pulley 44 and the driven pulley 45 are connected by a conveyor belt 46, and the driven pulley 45 is driven by the driving pulley 44 via the transmission belt 46. The driven pulley 45 is mounted on the pulley end cover 12 via the first bearing 23 and can rotate freely. The driving pulley 44 and the driven pulley 45 are connected by the conveyor belt 46.

[0050] The retractable fixing rod 51 includes a built-in retractable rod 511 and a housing 512. The built-in retractable rod 511 is hinged to the disc joint 62. One end of the housing 512 is fixed to the front edge side plate of the driven pulley 45, and the other end is fixedly connected to the grooved fixing ring 52, with a rotating ring 32 passing through the middle. The grooved fixing ring 52 is coaxially fixed to the protective shell 7 by screws. The rotating rod 53 can rotate around the groove on the grooved fixing ring 52. The driven pulley 45 is connected to the rotating ring 32, the rotating rod 53, and the disc joint 62 through the retractable fixing rod 51. The screw shaft 241 of the planetary roller screw 24 passes through the bearing at the center of the grooved fixing ring 52 and the bearing at the center of the driven pulley 45. When the disc joint 62 swings, the retractable fixing rod 51 extends and retracts accordingly.

[0051] The rotary transmission assembly 5 has its rotating rod 53 coaxially connected to the planetary roller screw 24, which is fixedly sleeved inside the differential rope drive device. One end of the metal rope 35 is movably mounted on the movable joint 6, and the other end is movably mounted on the driven pulley 45 of the second drive device.

[0052] The disc joint 62 is fixedly mounted on the ball joint 61. A slide is provided on the inner side of the disc joint 62 to guide the metal rope 35. The bottom of the ball joint 61 is fixedly connected to the swivel rod 53.

[0053] The working principle and process of this embodiment:

[0054] When the first motor 21 is working, it drives the screw shaft 241 of the planetary roller screw 24 to rotate, which in turn drives the nut 242 to move back and forth along the axial direction. The nut 242 drives the rotating ring 32, the contraction type conical screw 33, and the expansion type conical screw 34 to move together. Then, through the differential winding and unwinding of the two metal ropes 35 in the differential rope drive device, the disc joint 62 is pulled to deflect around the center of the ball joint 61, thereby realizing the swing freedom movement.

[0055] The retractable tapered screw 33 and the expanding tapered screw 34 are mounted on the rotating ring 32 via a third bearing 36. A metal rope 35 is wound around the two tapered screws of the rotating ring 32 with the same initial winding length. Translation of the rotating ring 32 forces the metal rope 35 to simultaneously wind or unwind on both tapered screws. Since the two tapered screws have opposite tapers, the same linear displacement of the nut 242 causes a corresponding change in the winding length of the metal rope 35 on the two tapered screws, creating a differential effect of winding and unwinding. This causes the disc joint 62 to deflect around the center of the ball joint 61, enabling multi-angle deflection oscillating motion.

[0056] When the second motor 41 is working, it drives the driven pulley 45 to rotate through the belt drive structure. The driven pulley 45 drives the rotating ring 32, the rotating rod 53, and the disc joint 62 to rotate synchronously through the telescopic fixed rod 51, realizing rotational motion. The rotating ring 32 drives the retractable conical screw 33 and the expanding conical screw 34 to revolve together around the axis of the screw shaft 241, and pulls the disc joint 62 to rotate around the axis of the screw shaft 241, realizing rotational freedom of motion. The driving pulley 44, the driven pulley 45, and the transmission belt 46 form a belt drive structure. The driven pulley 45 is driven by the driving pulley 44 through the transmission belt 46.

[0057] The telescopic fixed rod 51 simultaneously drives the rotating ring 32 and the rotating rod 53 to rotate around the axis of the lead screw shaft 241. Correspondingly, the rotating ring 32 drives the contracting conical lead screw 33 and the expanding conical lead screw 34 to revolve around the axis of the lead screw shaft 241, thereby pulling the metal rope 35 to revolve around the axis of the lead screw shaft 241, ensuring that no interference occurs during the rotation.

[0058] The telescopic fixed rod 51 can extend and retract to accommodate the movement of the disc joint 62 as it swings.

Claims

1. A differential rope drive based welding robot joint, characterized by: The utility model relates to a kind of rotary mechanism, including pedestal frame (1), first drive device (2), differential rope drive device, second drive device, rotary transmission assembly (5), movable joint (6) and protective shell (7);Wherein, one end of protective shell (7) is fixedly arranged on pedestal frame (1), one end of rotary transmission assembly (5) is fixedly arranged on protective shell (7), the other end is fixedly arranged on movable joint (6), differential rope drive device, first drive device (2) and second drive device are sequentially connected and arranged in protective shell (7); The base frame (1) includes a motor end cover (11), a pulley end cover (12), and a base frame shell (13). The first drive device (2) includes a first motor (21), a first coupling (22), a first bearing (23), and a planetary roller screw (24). The differential rope drive device includes a second bearing (31), a rotating ring (32), a contraction type conical screw (33), an expansion type conical screw (34), and a metal rope (35). The second drive device includes a second motor (41), a second coupling (42), a short shaft (43), a driving pulley (44), a driven pulley (45), a transmission belt (46), a semicircular tube (47), a rectangular platform (48), and a side plate (49). The rotary transmission assembly (5) includes an extendable fixed rod (51), a slotted fixed ring (52), and a rotating rod (53). The movable joint (6) includes a ball joint (61) and a disc joint (62). The motor end cover (11) is fixedly connected with the pulley end cover (12), and the motor end cover (11) and the pulley end cover (12) are fixedly arranged in the base frame shell (13). The first motor (21) and the second motor (41) are fixedly arranged on the motor end cover (11) of the base frame (1). The first motor (21) is connected with the screw shaft (241) of the planetary roller screw (24) through the first coupling (22), and the nut (242) is sleeved on the screw shaft (241). The rotating ring (32) is connected with the outer ring of the nut (242) through the second bearing (31). The contraction type conical screw (33) and the expansion type conical screw (34) are fixedly and symmetrically sleeved on both sides of the rotating ring (32) through the third bearing (36). The rotation directions of the two conical screws are the same, and the taper directions are opposite. The metal rope (35) is smooth on the surface and is a closed loop. The metal rope (35) is sleeved on the contraction type conical screw (33) and the expansion type conical screw (34). One side of the metal rope (35) is arranged in the slide inside the disc joint (62), and the other side is arranged in the semicircular tube (47) on the rectangular platform (48) on the surface of the driven pulley (45). The second motor (41) output shaft is connected with the second coupling (42), the other end of the second coupling (42) is connected with the short shaft (43), the driving pulley (44) is connected through the short shaft (43) and the second coupling (42), the driven pulley (45) side surface front edge is provided with the rectangular platform (48), the rectangular platform (48) is provided with the side plate (49), the driven pulley (45) is driven by the driving pulley (44) through the transmission belt (46); the driven pulley (45) is installed on the pulley end cover (12) through the first bearing (23) and can rotate freely; The telescopic fixed rod (51) includes a shell (512) and an internal telescopic rod (511), the internal telescopic rod (511) is hinged to the disc joint (62); one end of the shell (512) is fixed on the driven pulley (45) front edge side plate, the other end is fixedly connected with the slotted fixed ring (52), the middle is connected through the rotating ring (32), the internal telescopic rod (511) is fixedly connected with the disc joint (62), the slotted fixed ring (52) is coaxially fixedly connected with the protection shell (7), the rotating rod (53) can rotate around the slot of the slotted fixed ring (52), the driven pulley (45) is connected with the rotating ring (32), the rotating rod (53) and the disc joint (62) through the telescopic fixed rod (51); The rotating rod (53) of the rotary transmission assembly (5) is coaxially connected with the planetary roller screw (24), the planetary roller screw (24) is fixedly sleeved in the differential rope driving device; one end of the metal rope (35) is movably arranged on the movable joint (6), and the other end is movably arranged on the driven pulley (45) of the second driving device; one end of the telescopic fixed rod (51) is connected with the driven pulley (45), and the other end is connected with the disc joint (62) of the movable joint (6); The disc joint (62) is fixedly arranged on the ball joint (61), the inner side of the disc joint (62) is provided with a slide way for guiding the metal rope (35); the bottom of the ball joint (61) is fixedly connected with the rotating rod (53).

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