A multi-link double-finger vacuum robot arm

Abstract

The present application relates to a vacuum manipulator, in particular to a multi-link double-finger vacuum manipulator arm, comprising a left arm assembly, a right arm assembly and an end execution assembly, the left arm assembly and the right arm assembly each comprise a large arm and a small arm, the large arm and the small arm are connected through an elbow joint connecting mechanism, the wrist of the small arm is connected with the end execution assembly, the ends of the left arm assembly and the right arm assembly are physically integrated as a whole through the end execution assembly, the synchronous stretching and shrinking precision and the interval stability of the large interval double-finger are forcedly guaranteed, through the independent elbow joint connecting mechanism at the joint of the left arm assembly and the right arm assembly, the height of the small arm and its external connecting piece can be adjusted respectively, the flexible adaptation to the multi-height transmission station is realized, at the same time, through the height independent compensation, the assembly internal stress generated by the large interval parallel closed-loop mechanism is effectively released, the problems of movement interference, operation blockage and abnormal friction dust caused by the abnormal eccentric load borne by the joint bearing are solved.

Description

Technical Field

[0001] This invention relates to vacuum robotic arms, and more particularly to a multi-link dual-finger vacuum robotic arm. Background Technology

[0002] In the semiconductor manufacturing industry, vacuum robotic arms are core equipment for wafer handling. With increasing demands for production line efficiency, the need for synchronous dual-wafer handling at externally spaced parallel workstations is growing. To meet this need, existing solutions typically fall into two categories: one where the left and right arms are independently mounted and driven by different mechanisms. Due to the influence of control precision and mechanical drift, this solution struggles to guarantee a constant distance between the large fingers and absolute synchronization of their extension and retraction movements, resulting in limited transmission accuracy.

[0003] Another approach involves the left and right arms sharing the same front-end finger connector, achieving integration through a rigid physical connection. While this integrated structure theoretically improves synchronization, in applications with large spacing and spans, the left and right arms and the finger connector form a typical rigid closed-loop over-constraint mechanism. Due to machining tolerances and axial runout of the components, a slight height difference can easily occur between the left and right arms in the Z-axis direction after assembly.

[0004] Under this rigid closed-loop constraint, even a tiny height error can translate into enormous assembly internal stress. This causes abnormal off-center loading on the joint bearings during the robotic arm's operation in a vacuum environment, leading to motion interference, operational stagnation, and abnormal frictional dust generation, severely contaminating the wafers and shortening the equipment's lifespan. Furthermore, most existing elbow joints employ non-adjustable fixed structures, unable to flexibly adapt to multiple transmission stations with height differences according to production line requirements. Simultaneously, existing multi-axis coaxial drive structures have extremely stringent requirements for axial dimensional accuracy. Therefore, there is an urgent need to design a vacuum robotic arm that can maintain the large-pitch synchronization accuracy resulting from physical integration, effectively release internal stress, flexibly adapt to height, and reduce assembly difficulty. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a multi-link dual-finger vacuum robotic arm. This invention solves the problems of poor synchronization and difficulty in ensuring spacing accuracy in existing dual-arm systems through the physical integration design of the end caps of the left and right arms. Simultaneously, it utilizes an innovative elbow height adjustment and locking mechanism to solve the problem of abnormal off-center loads on joint bearings caused by over-constraint in large-spacing parallel closed-loop mechanisms, leading to motion interference and frictional dust generation. Furthermore, it reduces the dependence of the drive shaft system on the axial dimensional tolerances of the column connecting shaft.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: The present invention provides a multi-link dual-finger vacuum robotic arm, including a left arm assembly, a right arm assembly and an end effector assembly. The left arm assembly and the right arm assembly each include an upper arm and a forearm. The upper arm and the forearm are connected by an elbow joint connection mechanism. The end effector assembly is connected to the wrist of the forearm. The elbow joint connection mechanism includes a threaded shaft, a threaded adjusting seat, and an elbow sleeve. The threaded shaft is fixedly installed at the elbow of the upper arm. The threaded shaft is externally threaded to the threaded adjusting seat. The threaded adjusting seat supports the elbow sleeve which is sleeved outside the threaded shaft. A locking mechanism is provided in the annular gap between the threaded shaft and the elbow sleeve. The outside of the elbow sleeve is rotatably connected to the elbow of the forearm.

[0007] Furthermore, the locking mechanism includes a wedge-shaped elbow expansion sleeve and an elbow expansion sleeve cover. The elbow expansion sleeve is inserted into the annular gap between the threaded shaft and the elbow shaft sleeve, and the elbow expansion sleeve cover is fixedly installed on the top surface of the threaded shaft.

[0008] Furthermore, the end effector includes a finger connector and two fingers. The finger connector is connected to two wrist shafts, which are rotatably connected to the forearm wrists of the left arm assembly and the right arm assembly respectively via wrist bearings. The two fingers are mounted on the finger connector.

[0009] A multi-link dual-finger vacuum robotic arm also includes a coaxial drive mechanism, an upper turntable and a lower turntable. The upper arms of the left arm assembly and the right arm assembly are respectively fixedly installed on the upper turntable and the lower turntable. The lower turntable and the upper turntable are rotatably connected by a shoulder bearing. The coaxial drive mechanism includes an outer shaft, an inner shaft, and a tensioning assembly. The inner shaft is rotatably connected to the outer shaft, the outer shaft is fixedly connected to the lower turntable, and the upper turntable is fixedly connected to the inner shaft through the tensioning assembly.

[0010] Furthermore, a cross steel band is provided between the wrists of the forearms of the left and right arm components; The cross steel strip includes a first open-loop steel strip and a second open-loop steel strip arranged in a staggered layered manner along the axial height. The two ends of the first open-loop steel strip and the second open-loop steel strip are respectively anchored on the arcuate side of the wrist of the two forearms. The first open-loop steel strip and the second open-loop steel strip are arranged in a cross manner under the top view projection.

[0011] The advantages and positive effects of this invention are as follows: 1. This invention physically integrates the ends of the left and right arm components into a whole through a finger connector, which forcibly ensures the synchronous extension and retraction accuracy and spacing stability of the large-pitch double fingers, effectively improving the reliability of dual-wafer handling.

[0012] 2. This invention, through independent elbow joint connection mechanisms at the joints of the left and right arm components, can adjust the height of the forearm and its external connectors separately, achieving flexible adaptation to multiple height transmission stations. At the same time, through independent height compensation, it effectively releases the assembly internal stress generated by the large-spacing parallel closed-loop mechanism, solving the problems of motion interference, operation stagnation, and abnormal friction dust generation caused by abnormal off-center load on the joint bearing.

[0013] 3. This invention locks the annular gap between the threaded shaft and the elbow sleeve through a locking mechanism, thereby achieving radial zero backlash locking of the elbow joint adjustment mechanism and rigid pressing of the axial support position, ensuring the structural stability of the robotic arm under vacuum high-speed operation.

[0014] 4. This invention, through the design of cross steel strips, completely eliminates interference friction between steel strips while ensuring high-precision linear pose constraints.

[0015] 5. The upper turntable of the present invention is connected to the inner shaft by a tensioning assembly, which reduces the dependence of the coaxial drive mechanism on the axial dimension accuracy of the column shaft system and improves the assembly yield. Attached Figure Description

[0016] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the structure of a multi-link dual-finger vacuum robotic arm according to the present invention; Figure 2 This is a cross-sectional view of the elbow joint of the left arm assembly of a multi-link dual-finger vacuum robotic arm of the present invention in one of its working states. Figure 3 This is a cross-sectional view of the elbow joint of the right arm assembly of a multi-link dual-finger vacuum robotic arm of the present invention in one of its working states. Figure 4 This is a cross-sectional view of the coaxial drive mechanism of a multi-link dual-finger vacuum robotic arm according to the present invention. Explanation of reference numerals in the attached figures: 1. Upper turntable; 2. Lower turntable; 3. Left arm assembly; 3.1. Left upper arm; 3.2. Left forearm; 4. Right arm assembly; 4.1. Right upper arm; 4.2. Right forearm; 5. Two fingers; 6. Finger connector; 7. Elbow shaft inner ring cover; 8. Threaded shaft; 9. Wrist bearing; 10. Wrist shaft; 11. Elbow bearing; 12. Elbow expansion sleeve; 13. Threaded adjustment seat; 14. Elbow shaft sleeve; 15. Shoulder bearing; 16. Expansion sleeve mounting seat; 17. Center expansion sleeve; 18. Expansion sleeve cover; 19. Cross steel band; 20. Elbow locking bolt; 21. Elbow expansion sleeve cover; 22. Outer shaft; 23. Inner shaft. Detailed Implementation

[0017] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "fixation," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0018] The following is in conjunction with the appendix Figures 1 to 4 Preferred embodiments of the present invention will be described below. It should be understood that the embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0019] A multi-link dual-finger vacuum robotic arm includes a left arm assembly 3, a right arm assembly 4, and an end effector assembly; Referring to Figures 1 and 2, the left arm assembly 3 includes a left upper arm 3.1 and a left forearm 3.2, which are connected by an elbow joint connecting mechanism. Referring to Figures 1 and 3, the right arm assembly 4 includes a right upper arm 4.1 and a right forearm 4.2, which are connected by an elbow joint connecting mechanism. The wrists of the left forearm 3.2 and the right forearm 4.2 are connected to end effectors.

[0020] Reference Figure 2 As shown, taking the left arm assembly 3 as an example, the elbow joint connection mechanism includes a threaded shaft 8, a threaded adjusting seat 13, and an elbow shaft sleeve 14. The threaded shaft 8 is fixedly installed on the elbow of the left upper arm 3.1. The threaded shaft 8 is externally threaded to the threaded adjusting seat 13. The threaded adjusting seat 13 supports the elbow shaft sleeve 14 which is sleeved on the outside of the threaded shaft 8. A locking mechanism is provided in the annular gap between the threaded shaft 8 and the elbow shaft sleeve 14. The outside of the elbow shaft sleeve 14 is rotatably connected to the elbow of the left forearm 3.2 through an elbow bearing 11.

[0021] Specifically, an elbow bearing 11 is fitted on the outside of the elbow sleeve 14, and the outer ring of the elbow bearing 11 is fixedly connected to the elbow of the left forearm 3.2; the top surface of the elbow sleeve 14 is fixedly connected to the elbow inner ring cover 7 by fastening bolts, and the elbow inner ring cover 7 is axially positioned by tightening the fastening bolts so that the elbow inner ring cover 7 acts on the inner ring of the elbow bearing 11.

[0022] Reference Figure 1 , Figure 2 and Figure 3 As shown, the elbow connection structure of the left arm assembly 3 and the elbow connection structure of the right arm assembly 4 are symmetrically distributed. By rotating the threaded adjustment seat 13 to move it axially along the threaded shaft 8, the height of the left forearm 3.2 and the right forearm 4.2 can be adjusted independently, which can accurately compensate for the axial error generated by the parallel closed-loop mechanism and avoid abnormal off-center load on the joint bearing.

[0023] The locking mechanism includes a wedge-shaped elbow expansion sleeve 12 and an elbow expansion sleeve cover 21. The elbow expansion sleeve 12 is inserted into the annular gap between the threaded shaft 8 and the elbow shaft sleeve 14. The top surface of the threaded shaft 8 has an internal threaded hole, and the internal threaded hole is threadedly connected to the elbow locking bolt 20. The elbow expansion sleeve cover 21 is screwed into the internal threaded hole by the elbow locking bolt 20 to tighten the elbow expansion sleeve 12.

[0024] When the elbow locking bolt 20 is tightened, the elbow expansion sleeve cover 21 applies an axial force downward to squeeze the elbow expansion sleeve 12. Due to the wedge-shaped structure of the elbow expansion sleeve 12, the elbow expansion sleeve 12 expands radially to lock the gap between the elbow shaft sleeve 14 and the threaded shaft 8. At the same time, the axial tightening force is transmitted downward to fasten the threaded adjusting seat 13 to the threaded shaft 8.

[0025] The end effector includes a finger connector 6 and two fingers 5. The finger connector 6 is connected to two wrist shafts 10. The two wrist shafts 10 are rotatably connected to the wrists of the left forearm 3.2 and the right forearm 4.2 respectively via wrist bearings 9. The two fingers 5 are mounted on the finger connector 6.

[0026] The distance between the wrists of the left forearm 3.2 and the right forearm 4.2 is fixed by the finger connector 6, thereby ensuring the synchronicity and spacing stability of the two widely spaced fingers 5 during the extension and retraction process.

[0027] In this embodiment, a coaxial drive mechanism is used to drive the left arm assembly 3 and the right arm assembly 4 to run simultaneously. It is by no means limited to this one coaxial drive mechanism or different drive mechanisms to drive the left arm assembly 3 and the right arm assembly 4 to run synchronously.

[0028] Reference Figure 1 and Figure 4 As shown, a multi-link dual-finger vacuum robotic arm also includes a coaxial drive mechanism, an upper turntable 1 and a lower turntable 2. The left upper arm 3.1 and the right upper arm 4.1 are respectively fixedly installed on the upper turntable 1 and the lower turntable 2. The lower turntable 2 and the upper turntable 1 are supported by a shoulder bearing 15 to form a relative rotational support. The coaxial drive mechanism includes an outer shaft 22, an inner shaft 23, and a tensioning assembly. The inner shaft 23 is coaxially rotatably connected to the outer shaft 22, and the outer shaft 22 is fixedly connected to the lower turntable 2. The upper turntable 1 is fixedly connected to the inner shaft 23 through the tensioning assembly. The drive structure that drives the inner shaft 23 to rotate relative to the outer shaft 22 is a relatively mature technology in the prior art. No technical improvements have been made to this part, so it will not be described in detail.

[0029] The tensioning assembly includes a central tensioning sleeve 17, a tensioning sleeve mounting base 16, and a tensioning sleeve cover 18. The central tensioning sleeve 17 is installed inside the tensioning sleeve mounting base 16, which is sleeved on the inner shaft 23. The tensioning sleeve mounting base 16 is fixed to the upper turntable 1 by fixing bolts. By turning the cover bolts on the tensioning sleeve mounting base 16, the tensioning sleeve cover 18 is pushed to move axially. When the cover bolts are turned, the tensioning sleeve cover 18 pushes the central tensioning sleeve 17 axially. Axial tightening is achieved through the radial deformation of the central tensioning sleeve 17, and the upper turntable 1 is fixed to the inner shaft 23. The driving torque is transmitted through the radial deformation of the central tensioning sleeve 17, which can effectively reduce the dependence of the drive shaft system on the axial dimensional accuracy of the column at the assembly interface.

[0030] A cross steel band 19 is provided between the wrist arc side of the left forearm 3.2 and the right forearm 4.2. The cross steel band 19 includes a first open-loop steel band and a second open-loop steel band arranged in a staggered manner in axial height. The two ends of the first open-loop steel band and the second open-loop steel band are respectively anchored to the arc side of the wrist of the left forearm 3.2 and the right forearm 4.2, so that the first open-loop steel band and the second open-loop steel band are arranged in a cross manner in the top view projection, and do not contact each other in the height direction.

[0031] When the left forearm 3.2 drives the wrist to rotate clockwise, the first or second open-loop steel belt is tightened, pulling the wrist of the right forearm 4.2 to rotate counterclockwise. The first or second open-loop steel belt that was not tightened is released but still maintains pre-tension and will not sag.

[0032] When the left forearm 3.2 drives the wrist to rotate counterclockwise, the first or second open-loop steel belt is tightened, pulling the wrist of the right forearm 4.2 to rotate clockwise. The first or second open-loop steel belt that was not tightened is released but still maintains pre-tension and will not sag.

[0033] The coaxial drive mechanism drives the inner shaft 23 and the outer shaft 22 to rotate. The inner shaft 23 and the outer shaft 22 respectively drive the upper turntable 1 and the lower turntable 2 to rotate relative to each other. The relative rotation of the upper turntable 1 and the lower turntable 2 will pull the left upper arm 3.1 and the right upper arm 4.1 to deflect, thereby adjusting the opening and closing angle between the left upper arm 3.1 and the right upper arm 4.1. The left forearm 3.2 and the right forearm 4.2 follow the corresponding upper arm to extend and retract synchronously. Relying on the transmission constraint of the cross steel belt 19, the wrist of the left forearm 3.2 and the right forearm 4.2 rotates in the clockwise and counterclockwise directions respectively, and the rotation angle of the two always remains consistent.

[0034] The working principle of this invention is as follows: Before wafer handling, the heights of the left forearm 3.2 and right forearm 4.2 under rigid closed-loop constraints are adjusted by the elbow joint connection mechanism to avoid the conversion of small height errors into huge assembly internal stresses, so as to meet the working conditions. After adjustment, the end effector is used to handle the wafer.

[0035] During operation, the outer shaft 22 and the inner shaft 23 jointly drive the lower turntable 2 and the upper turntable 1 to rotate relative to each other, driving the right upper arm 4.1 and the left upper arm 3.1 to extend, so that the corresponding two elbow joint connecting mechanisms perform planetary motion around the center of the main shaft. Under the positional constraints of the left forearm 3.2 and the right forearm 4.2 on the cross steel belt 19, the left forearm 3.2 and the right forearm 4.2 are driven to extend and retract synchronously, driving the finger connector 6 and the two fingers 5 to complete the horizontal linear transmission action.

[0036] The robotic arm provided in this embodiment, through the physical integration design achieved by the finger connector 6, ensures the accuracy of synchronous transmission at large intervals; while the height adjustment and locking through the elbow joint connection mechanism effectively releases the over-constraint internal stress brought about by integration and eliminates frictional dust caused by motion interference.

Claims

1. A multi-link dual-finger vacuum robotic arm, comprising a left arm assembly, a right arm assembly, and an end effector assembly, wherein both the left and right arm assemblies include an upper arm and a forearm, characterized in that, The upper arm and forearm are connected by an elbow joint connection mechanism, and the wrist of the forearm is connected to an end effector. The elbow joint connection mechanism includes a threaded shaft, a threaded adjusting seat, and an elbow sleeve. The threaded shaft is fixedly installed at the elbow of the upper arm. The threaded shaft is externally threaded to the threaded adjusting seat. The threaded adjusting seat supports the elbow sleeve which is sleeved outside the threaded shaft. A locking mechanism is provided in the annular gap between the threaded shaft and the elbow sleeve. The outside of the elbow sleeve is rotatably connected to the elbow of the forearm.

2. The multi-link dual-finger vacuum robotic arm according to claim 1, characterized in that, The locking mechanism includes a wedge-shaped elbow expansion sleeve and an elbow expansion sleeve cover. The elbow expansion sleeve is inserted into the annular gap between the threaded shaft and the elbow shaft sleeve. The elbow expansion sleeve cover is fixedly installed on the top surface of the threaded shaft.

3. The multi-link dual-finger vacuum robotic arm according to claim 1, characterized in that, The end effector assembly includes a finger connector and two fingers. The finger connector is connected to two wrist shafts, which are rotatably connected to the forearm wrists of the left arm assembly and the right arm assembly respectively via wrist bearings. The two fingers are mounted on the finger connector.

4. The multi-link dual-finger vacuum robotic arm according to claim 1, characterized in that, It also includes a coaxial drive mechanism, an upper turntable and a lower turntable. The upper arms of the left arm assembly and the right arm assembly are fixedly installed on the upper turntable and the lower turntable, respectively. The lower turntable and the upper turntable are rotatably connected by a shoulder bearing. The coaxial drive mechanism includes an outer shaft, an inner shaft, and a tensioning assembly. The inner shaft is rotatably connected to the outer shaft, the outer shaft is fixedly connected to the lower turntable, and the upper turntable is fixedly connected to the inner shaft through the tensioning assembly.

5. The multi-link dual-finger vacuum robotic arm according to claim 1, characterized in that, Cross steel straps are provided between the wrists of the forearms of the left and right arm components; The cross steel strip includes a first open-loop steel strip and a second open-loop steel strip arranged in a staggered layered manner along the axial height. The two ends of the first open-loop steel strip and the second open-loop steel strip are respectively anchored on the arcuate side of the wrist of the two forearms. The first open-loop steel strip and the second open-loop steel strip are arranged in a cross manner under the top view projection.

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