A wrist rotation device on a robot arm

Abstract

The utility model provides a wrist rotating device on mechanical arm, including small arm main part, moving screw rod, linear push jar, rotation screw bush and wrist base. Moving screw rod can be axially mobile and is arranged on small arm main part, and linear push jar is installed in small arm main part, and its telescopic rod is connected moving screw rod to drive its axial movement. Rotation screw bush is rotatably connected in small arm main part and is set up in moving screw rod outside, and both are through thread cooperation with moving screw rod's axial movement is converted into rotary motion, and then drive wrist base and mechanical palm of rotation screw bush connection rotate. The device simple and compact structure, replaced traditional servo motor and speed reducer combination, effectively reduce the component quantity and assembly error, improve positioning accuracy and load capacity, reduce the debugging difficulty and maintenance cost, be applicable to industrial automation etc.

Description

Technical Field

[0001] This utility model relates to the field of robotic arm technology, and more specifically, to a wrist rotation device on a robotic arm. Background Technology

[0002] In fields such as industrial automation, precision manufacturing, and medical assistance, robotic arms, as core components for adjusting the posture of end effectors, directly determine the overall operational efficiency of the equipment through their operational stability, control precision, and structural simplicity. Currently, mainstream wrist drive solutions for robotic arms commonly employ a combined transmission structure of a servo motor and a reducer. The reducer often utilizes harmonic reducers or RV reducers to achieve precise wrist rotation drive through speed reduction and torque amplification.

[0003] However, this traditional drive structure has significant technical limitations: First, it is highly complex. The servo motor and reducer need to be rigidly connected through couplings, flanges, and other components, which not only increases the overall size and weight of the wrist module, leading to a decrease in the load capacity of the robotic arm's end effector, but also easily causes jamming or positioning deviations during wrist rotation due to the accumulation of assembly errors of multiple components. Second, it is difficult to control and debug. The speed and torque parameters of the servo motor need to be strictly matched with the transmission ratio of the reducer. During debugging, it is necessary to repeatedly calibrate with specialized control software, which not only consumes a lot of manpower and time, but also places high demands on the professional skills of the operators. Especially in multi-axis collaborative operation scenarios, improper parameter debugging can easily lead to deviation of the wrist movement trajectory. Third, it is expensive to maintain. The internal mechanical components of the servo motor and reducer are in a state of high-speed operation for a long time, which is prone to wear and lubrication failure. When replacing parts, the entire drive module needs to be disassembled, which not only prolongs the equipment downtime, but also increases the economic cost of subsequent maintenance, making it difficult to meet the needs of efficient and low-cost operation in industrial production. Utility Model Content

[0004] The main technical problem addressed by this application is the complexity, high debugging difficulty, and high maintenance cost of existing robotic arm wrist drive devices. To overcome the above-mentioned defects of the prior art, this application provides a wrist rotation device for a robotic arm.

[0005] This application provides a wrist rotation device on a robotic arm, comprising: Forearm body; A movable screw is movably mounted on the forearm body along its own axis, and the movable screw is coaxially mounted with the forearm body; A linear push cylinder has its cylinder seat mounted on the forearm body. The telescopic rod of the linear push cylinder is connected to the movable screw, which is used to drive the movable screw to reciprocate along the axial direction. A rotating screw sleeve is rotatably connected to the forearm body, and the rotating screw sleeve is coaxially sleeved on the moving screw and threadedly matched with the moving screw. A wrist base, which is connected to a rotating screw sleeve, is located on the front side of the forearm body and is used to connect the robotic hand.

[0006] Compared with existing technologies, the wrist rotation device for a robotic arm disclosed in this application has the following advantages: It eliminates the need for complex components such as servo motors, reducers, and couplings. A linear push cylinder directly drives the axial movement of a moving screw, which is then converted into rotational motion of a rotating sleeve through threaded engagement. This significantly reduces the number of parts and assembly steps in the wrist module, lowering the overall size and weight while increasing the load capacity of the robotic arm's end effector. It reduces the accumulation of errors caused by multi-part assembly. The directness of the threaded drive avoids wrist jamming or positioning deviations caused by loose couplings or reducer wear in traditional structures, ensuring more precise wrist base rotation positioning. It eliminates the need for complex parameters such as matching servo motor speed, torque, and reducer transmission ratio. The wrist rotation angle can be indirectly controlled simply by controlling the extension rod stroke of the linear push cylinder, reducing repeated calibrations and lowering the skill requirements for operators. It is particularly suitable for rapid debugging in multi-axis collaborative operation scenarios. With no high-speed rotating motor rotors, reducer gears, or other easily damaged components, the wear rate is low. Subsequent maintenance does not require disassembling the entire drive module, shortening equipment downtime and reducing maintenance manpower and economic costs.

[0007] In one possible implementation, the linear push cylinder is a hydraulic push cylinder or a pneumatic push cylinder. Compared with the prior art, hydraulic push cylinders and pneumatic push cylinders are mature technologies with simple structures (no complex circuits, rotors, or other components), fewer potential failure points, and only require periodic inspection of the seals and hydraulic / pneumatic circuits. The maintenance difficulty is far lower than that of servo motor and reducer combinations, further extending the service life of the equipment.

[0008] In one possible implementation, a rotary bearing is fitted onto the outer wall of the rotary sleeve, and the rotary bearing is mounted on a bearing housing, which is fixedly connected to the forearm body. Compared with the prior art, the bearing housing is fixed to the forearm body, and the rotary bearing can provide precise radial positioning for the rotary sleeve, preventing radial offset during rotation and ensuring that the rotary sleeve and the moving screw remain coaxial, thereby ensuring smooth and wobbly rotation of the wrist base. The low resistance characteristics of rolling friction reduce power loss during the transmission process of the "moving screw and rotary sleeve," ensuring that the thrust of the linear push cylinder can be more efficiently converted into the rotational torque of the wrist.

[0009] In one possible implementation, two rotary bearings are provided, spaced apart along the axial direction of the rotary sleeve, and respectively positioned near both ends of the rotary sleeve. Compared with the prior art, the two bearings, spaced apart along the axis and close to both ends of the rotary sleeve, form a "two-end support" structure, which can effectively resist the bending deformation of the rotary sleeve caused by its own length or radial force. This is especially suitable for designs with longer rotary sleeves, improving the overall structural rigidity.

[0010] In one possible implementation, the outer wall of the movable screw is provided with an external thread, and the inner wall of the rotating sleeve is provided with an internal thread. The internal thread and the external thread are matched to form a threaded transmission fit. Compared with the prior art, the precise matching of the internal and external threads can achieve a fixed transmission ratio of "axial stroke of the movable screw and rotation angle of the rotating sleeve". By controlling the extension and retraction length of the telescopic rod of the linear push cylinder, the rotation angle of the wrist base can be accurately calculated and controlled, avoiding slippage or idle stroke during power transmission and improving positioning accuracy.

[0011] In one possible implementation, two linear push cylinders are provided, symmetrically distributed around the moving screw. The two telescopic rods are fixed together by a connecting rod that passes through the moving screw. Compared to existing technologies, the symmetrical distribution of the two linear push cylinders around the moving screw allows for the application of symmetrical axial thrust to the moving screw, preventing unilateral force on the moving screw during single-cylinder operation and ensuring smooth axial movement of the moving screw, thus preventing jamming of the threaded transmission. The connecting rod passing through the moving screw and fixing the two telescopic rods forces the telescopic rods of the two linear push cylinders to extend and retract synchronously, preventing asynchronous movement due to pressure fluctuations in the push cylinders, ensuring uniform axial movement of the moving screw, and thus guaranteeing the smooth rotation of the rotating sleeve and reducing impact during wrist base rotation. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the overall structure of this application; Figure 2 This is a partial cross-sectional view of this application; Explanation of reference numerals in the attached figures: 1. Forearm body; 2. Moving screw; 3. Linear push cylinder; 31. Cylinder seat; 32. Telescopic rod; 4. Rotating screw sleeve; 5. Wrist base; 6. Rotary bearing; 7. Bearing seat; 8. Connecting rod. Detailed Implementation

[0013] First, those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the embodiments of this application and are not intended to limit the scope of protection of the embodiments of this application. Those skilled in the art can make adjustments as needed to adapt to specific application scenarios.

[0014] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" 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. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0015] In the embodiments of this application, unless otherwise expressly 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.

[0016] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0017] See Figure 1 and Figure 2 This application discloses a wrist rotation device on a robotic arm, comprising: a forearm body 1, a moving screw 2, a linear push cylinder 3, a rotating screw sleeve 4, and a wrist base 5.

[0018] The forearm body 1, serving as the basic support structure of the device, is typically made of aluminum alloy, high-strength steel, or carbon fiber composite material and is fixedly connected to the robotic arm. The interior of the forearm body 1 is hollow to accommodate other components.

[0019] The movable screw 2 is made of high-strength steel threaded rod, and its outer surface is machined with precision external threads. The movable screw 2 is installed inside the forearm body 1, and it can move along its own axis and is coaxial with the forearm body 1.

[0020] The linear push cylinder 3 is a hydraulic push cylinder, with its cylinder seat 31 fixed to the main body 1 of the boom by bolts. The hydraulic system is connected to the hydraulic push cylinder through oil pipes, and the precise movement of the telescopic rod 32 is achieved by controlling the inflow and outflow of oil. The telescopic rod 32 of the linear push cylinder 3 is connected to the rear end of the moving screw 2. When the telescopic rod 32 extends or retracts, it drives the moving screw 2 to reciprocate axially. In other embodiments, the linear push cylinder 3 may also be a pneumatic push cylinder.

[0021] The rotating sleeve 4 is made of high-strength alloy, and its inner hole is machined with precision internal threads that match the external threads of the moving screw 2. The rotating sleeve 4 is rotatably connected to the forearm body 1 and coaxially sleeved on the outside of the moving screw 2. When the moving screw 2 moves axially, it drives the rotating sleeve 4 to rotate through threaded transmission. The fit between the external and internal threads has a self-locking characteristic.

[0022] The wrist base 5 has a disc-shaped structure and is connected to the front end of the rotating screw sleeve 4. The wrist base 5 is located on the front side of the forearm body 1 and has an interface for connecting the robotic hand.

[0023] The device is driven by a control module to operate the linear push cylinder 3. When the linear push cylinder 3 drives the moving screw 2 forward, the rotating sleeve 4 rotates under the action of the thread, driving the wrist base 5 and the robotic hand to rotate; when the moving screw 2 moves backward, the rotating sleeve 4 rotates in the opposite direction, realizing the reciprocating rotation of the wrist. This design converts linear motion into rotational motion, has a compact structure, and is simple to control.

[0024] In this embodiment, two rotary bearings 6 are fitted onto the outer wall of the rotary sleeve 4. The two rotary bearings 6 are arranged at intervals along the axial direction of the rotary sleeve 4, with one bearing near the front end of the rotary sleeve 4 and the other near the rear end. The two rotary bearings 6 are respectively mounted on two bearing seats 7, which are fixedly connected to the forearm body 1. The rotary bearings 6 are deep groove ball bearings, with the inner ring of the bearing having an interference fit with the rotary sleeve 4 and the outer ring having a clearance fit with the bearing seat 7. The bearing seat 7 has a bearing mounting groove machined in its inner hole for mounting the rotary bearing 6, and the two bearing seats 7 axially limit the rotary sleeve 4.

[0025] In this embodiment, two identical linear push cylinders 3 are symmetrically distributed around the axis of the moving screw 2, and their cylinder seats 31 are fixed to the forearm body 1 by a bracket. The ends of the two telescopic rods 32 are connected by a connecting rod 8, which is a rigid rod that passes through a through hole at the rear of the moving screw 2. The connecting rod 8 is perpendicular to the moving screw 2. The two push cylinders move synchronously, applying a uniform thrust to the moving screw 2 through the connecting rod 8, avoiding uneven load caused by unilateral drive. This symmetrical design improves the linear motion accuracy of the moving screw 2, reduces wear, and is suitable for high-precision operations.

[0026] The beneficial effects of this application include: First, simplify the structure and reduce weight by eliminating complex components such as servo motors, reducers, and couplings, thereby reducing the number of parts and assembly steps, reducing the size and weight of the device, and improving the load capacity of the robotic arm's end effector.

[0027] II. Improve positioning accuracy and stability, reduce the accumulation of assembly errors of multiple parts, avoid jamming and positioning deviation of traditional structure by threaded transmission, and prevent radial offset and bending of rotating threaded sleeve 4 by the support of both ends of the double rotary bearing 6, ensuring the smooth rotation of wrist base 5.

[0028] Third, it reduces the difficulty of debugging. There is no need to match complex parameters such as motor speed, torque and reducer transmission ratio. The wrist rotation angle can be adjusted simply by controlling the stroke of the linear push cylinder 3 telescopic rod 32. It is suitable for rapid debugging of multi-axis collaborative operation and reduces the skill requirements of operators.

[0029] Fourth, it reduces maintenance costs and downtime, has no high-speed operating vulnerable parts, has a low wear rate, and does not require disassembling the entire drive module for maintenance.

[0030] 5. Optimize power transmission. The dual linear push cylinders 3 are symmetrically distributed and move synchronously through the connecting rod 8, avoiding the skew of the moving screw 2 and transmission jamming, reducing wrist rotation impact, adapting to high-precision operation, and meeting the industrial demand for high efficiency and low cost.

[0031] In the description of the embodiments of this application, it should be noted that the terms "inner" and "outer" and other terms indicating direction or positional relationship are based on the direction or positional relationship shown in the drawings. This is only for the convenience of description and does not indicate or imply that the device or component must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this application.

[0032] In the description of this application, the references to terms such as "an embodiment," "some embodiments," "in this embodiment," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the 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 a suitable manner in any one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0033] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A wrist rotation device on a robotic arm, characterized in that, include: Forearm body; A movable screw is movably mounted on the forearm body along its own axis, and the movable screw is coaxially mounted with the forearm body; A linear push cylinder has its cylinder seat mounted on the forearm body. The telescopic rod of the linear push cylinder is connected to the movable screw, which is used to drive the movable screw to reciprocate along the axial direction. A rotating screw sleeve is rotatably connected to the forearm body, and the rotating screw sleeve is coaxially sleeved on the moving screw and threadedly matched with the moving screw. A wrist base, which is connected to a rotating screw sleeve, is located on the front side of the forearm body and is used to connect the robotic hand.

2. The wrist rotation device on the robotic arm according to claim 1, characterized in that, The linear push cylinder is either a hydraulic push cylinder or a pneumatic push cylinder.

3. The wrist rotation device on the robotic arm according to claim 1, characterized in that, A rotary bearing is fitted onto the outer wall of the rotary sleeve, and the rotary bearing is mounted on a bearing seat, which is fixedly connected to the forearm body.

4. The wrist rotation device on the robotic arm according to claim 3, characterized in that, Two rotary bearings are provided, and the two rotary bearings are arranged at intervals along the axial direction of the rotary sleeve, and the two rotary bearings are respectively located near the two ends of the rotary sleeve.

5. The wrist rotation device on the robotic arm according to claim 1, characterized in that, The outer wall of the movable screw is provided with an external thread, and the inner wall of the rotating screw sleeve is provided with an internal thread. The internal thread and the external thread are matched to form a threaded transmission fit.

6. The wrist rotation device on the robotic arm according to claim 1, characterized in that, Two linear push cylinders are provided, and the two linear push cylinders are symmetrically distributed around the moving screw. The two telescopic rods are fixed together by a connecting rod, which passes through the moving screw.

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