Foldable reconfigurable parallel robot for inner wall grinding of large deep cavity parts

Abstract

The present invention provides a foldable reconfigurable parallel robot for grinding the inner wall of large deep cavity parts, including a first foldable mobile parallel robot and a second reconfigurable parallel robot; the first foldable mobile parallel robot includes: a frame fixed platform, a first moving platform and a plurality of first branches, the first branch includes a plurality of mutually cooperating rotating pairs, the bottom of the first branch is rotationally matched with the frame fixed platform, and the top of the first branch is rotationally matched with the first moving platform; the second reconfigurable parallel robot includes: a second moving platform, a passive branch and a plurality of second branches, the bottom of the second branch is mounted on the first branch, and the top of the second branch is rotationally matched with the second moving platform. The present invention can output two-turn and one-shift three-degree-of-freedom motion by driving each branch. The change of the terminal output motion is achieved by locking the drive motor or using a limit locking device, which helps to achieve efficient grinding of large deep cavity parts under different inner diameter conditions.

Description

Technical Field

[0001] The invention relates to the field of industrial robots, and in particular to a foldable reconfigurable parallel robot used for grinding the inner walls of large deep-cavity parts. Background Art

[0002] Large deep cavity complex parts are an important part of the core equipment in the fields of aerospace, energy and national defense. They have the characteristics of complex inner wall shape, poor openness, and difficult grinding process control. Based on the above characteristics, existing processing equipment, such as traditional multi-axis CNC machine tools and processing robots based on serial robots, cannot be used for inner wall grinding of large deep cavity parts due to the limitations of the main body structure or equipment precision / rigidity.

[0003] In view of the above situation, manual processing is currently mainly used to achieve the inner wall grinding of large deep cavity parts, but there are problems such as high labor intensity, low processing efficiency, poor product quality, and difficulty in health protection. Therefore, it is necessary to use suitable parts inner wall processing equipment as a replacement. In addition, since some large deep cavity parts have a change in inner diameter, that is, the inner diameter of the part will change with the increase in depth. Therefore, in order to achieve effective overall grinding, the processing equipment used must also adapt to different inner diameters.

[0004] The existing Chinese patent with publication number CN110682192B discloses a robot grinding equipment and method for the inner cavity of a large container. The equipment includes a robot, a robot linear axis, a workpiece conveyor, a tool library, a rotary table, a workpiece clamping fixture, an end effector, a dust removal device, a grinding room, etc.

[0005] Compared with cantilever chain serial robots, parallel robots are composed of a fixed platform, a moving platform and several motion branches in parallel. They have the advantages of compact structure, high precision and good rigidity, and have been widely used in material sorting and handling, mechanical processing and other fields. By driving the motion branches, traditional parallel robots can only move according to given degrees of freedom, which has certain limitations in application. Different from traditional parallel robots, reconfigurable parallel robots not only retain the inherent advantages of parallel robots, but also can change the terminal output motion by locking the drive motor or using a limit locking device to adapt to different scenarios. Therefore, in view of the current processing status of the inner wall grinding of large deep cavity parts, it is very necessary to propose a foldable reconfigurable parallel robot for the inner wall grinding of large deep cavity parts. Summary of the invention

[0006] In view of the defects in the prior art, the purpose of the present invention is to provide a foldable reconfigurable parallel robot for grinding the inner wall of large deep cavity parts.

[0007] According to the present invention, a foldable reconfigurable parallel robot for grinding the inner wall of large deep cavity parts includes a first foldable mobile parallel robot and a second reconfigurable parallel robot; the first foldable mobile parallel robot includes a frame fixed platform, a first moving platform and a plurality of first branches, the first branch includes a plurality of mutually cooperating rotating pairs, the bottom of the first branch is rotationally matched with the frame fixed platform, the top of the first branch is rotationally matched with the first moving platform, and the plurality of first branches are evenly arranged around the center of the frame fixed platform; the second reconfigurable parallel robot includes: a second moving platform, a passive branch and a plurality of second branches, the two ends of the passive branch are respectively connected to the first moving platform and the second moving platform; the second branch is arranged corresponding to the first branch, the bottom of the second branch is installed on the first branch, and the top of the second branch is rotationally matched with the second moving platform.

[0008] Preferably, the first branch includes three branches; the first branch includes a first bearing seat, a second bearing seat, a first rotating pair, a first connecting rod, a second rotating pair, a second connecting rod and a third rotating pair, the first bearing seat and the second bearing seat are fastened and mounted on the fixed platform of the frame, the first bearing seat and the second bearing seat are rotationally matched with the first connecting rod through the first rotating pair, the first moving pair is rotationally matched with the first connecting rod through the first rotating pair, the first connecting rod is rotationally matched with the second connecting rod through the second rotating pair, and the second connecting rod is rotationally matched with the first moving platform through the third rotating pair.

[0009] Preferably, the rotation axes of the first rotation pair, the second rotation pair and the third rotation pair are parallel to each other.

[0010] Preferably, the second branch includes a first movable pair, a first ball joint, a third connecting rod and a second ball joint, the first movable pair is installed on the second connecting rod, the first movable pair is rotationally matched with the third connecting rod through the first ball joint, and the third connecting rod is rotationally matched with the second movable platform through the second ball joint.

[0011] Preferably, the first movable pair includes a first movable pair guide rail and a first movable pair slider, the first movable pair slider is installed on the first movable pair guide rail, and the two are slidingly matched; the first movable pair guide rail is fastened to the second connecting rod, and the first movable pair slider is connected to the first ball joint and rotates together.

[0012] Preferably, the first rotating pair includes a driving pair, a driver is mounted on the first rotating pair, and the driver includes a motor and a gear driver; the first moving pair includes a driving pair, and the driving mechanism of the first moving pair includes a ball screw mechanism driven by a motor.

[0013] Preferably, the passive branch includes a bearing seat, a Hooke's hinge and a second movable pair, and the two ends of the second movable pair are rotatably matched with the bearing seat through the Hooke's hinge, and the two bearing seats are respectively fastened and installed on the top of the first moving platform and the bottom of the second moving platform.

[0014] Preferably, the second moving pair includes a first passive rod and a second passive rod arranged vertically; the Hooke's hinge includes a first Hooke's hinge and a second Hooke's hinge; the first Hooke's hinge includes a first rotating shaft and a second rotating shaft, the first rotating shaft cooperates with the bearing seat to form a rotating pair, and the second rotating shaft is connected to the first passive rod; the second Hooke's hinge includes a first rotating shaft and a second rotating shaft, the first rotating shaft cooperates with the bearing seat to form a rotating pair, and the second rotating shaft is connected to the second passive rod.

[0015] Preferably, the axes of the second rotating shaft, the first rotating shaft and the second moving pair are arranged perpendicularly to each other; the axes of the second rotating shaft, the first rotating shaft and the second moving pair are arranged perpendicularly to each other.

[0016] Preferably, the passive branch further includes a limit locking device, and the limit locking device is used to control the locking or releasing of the second rotating shaft, the first rotating shaft, the second rotating shaft and the first rotating shaft respectively.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The present invention is formed by connecting a fixed platform, a first moving platform, a second moving platform and a plurality of branches in parallel. By driving each branch, two rotations and one translation can be output to achieve three-degree-of-freedom motion. By locking the drive motor or using a limit locking device to change the output motion at the end, it is helpful to achieve efficient grinding of large deep cavity parts under different inner diameters.

[0019] 2. The present invention can move according to given degrees of freedom through the coordinated use of multiple drive pairs and multiple limit locking devices. It can also adapt to different scenarios and different inner diameter conditions, achieve different three-degree-of-freedom motion outputs and complete grinding, which helps to improve the scope of application.

[0020] 3. The present invention connects various platforms through the first branch, the second branch and the passive branch, and has a compact structure, high precision, good rigidity and strong load capacity, which helps to improve environmental adaptability and helps to achieve efficient grinding of large deep cavity parts under different inner diameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0022] Figure 1 This is a schematic diagram of the overall structure of a foldable reconfigurable parallel robot used for grinding the inner wall of large deep cavity parts;

[0023] Figure 2 This is a schematic diagram of the three-dimensional structure of a first foldable mobile parallel robot mainly embodied in the present invention;

[0024] Figure 3 It is a schematic diagram of the three-dimensional structure of the second reconfigurable parallel robot mainly embodied in the present invention;

[0025] Figure 4 This is a schematic diagram of the three-dimensional structure of the present invention mainly embodies the grinding of large deep cavity variable diameter parts;

[0026] Figure 5 This is a schematic diagram of the three-dimensional structure of the first branch of the present invention;

[0027] Figure 6 This is a schematic diagram of the three-dimensional structure of the second branch of the present invention;

[0028] Figure 7 It is a schematic diagram of the three-dimensional structure of the passive branch mainly embodied in the present invention.

[0029] As shown in the figure:

[0030] Frame fixed platform 1 First bearing seat 11

[0031] Second bearing seat 12 First rotating pair 13

[0032] First connecting rod 14 Second rotating pair 15

[0033] Second connecting rod 16 Third rotating pair 17

[0034] First moving platform 2 First moving auxiliary guide rail 21

[0035] First moving auxiliary slider 22 First ball joint 23

[0036] The third connecting rod 24 The second ball joint 25

[0037] Second moving platform 3 First bearing seat 31

[0038] Second bearing seat 32 Third bearing seat 33

[0039] Fourth bearing seat 34 First limit locking device 35

[0040] The first small limit motor 351 The first active limit rod 352

[0041] First limiting ring 353 Second limiting locking device 36

[0042] Second small limit motor 361 Second active limit rod 362

[0043] Second limiting ring 363 Third limiting locking device 37

[0044] The third small limiting motor 371 The third active limiting rod 372

[0045] The third limiting ring 373 The fourth limiting locking device 38

[0046] Fourth small limit motor 381 Fourth active limit rod 382

[0047] Fourth limiting ring 383 First Hooke hinge 39

[0048] Second Hooke's hinge 310 First passive rod 311

[0049] The second passive rod 312 The first rotation axis 313

[0050] Second rotation axis 314 First rotation axis 315

[0051] Second rotating shaft 316 Deep cavity type variable diameter part 4 DETAILED DESCRIPTION

[0052] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0053] like Figure 1-4 As shown, a foldable reconfigurable parallel robot for grinding the inner wall of large deep cavity parts provided according to the present invention includes a first foldable mobile parallel robot and a second reconfigurable parallel robot; the first foldable mobile parallel robot includes a frame fixed platform 1, a first moving platform 2 and a plurality of first branches, the first branch includes a plurality of mutually cooperating rotating pairs, the bottom of the first branch is rotationally matched with the frame fixed platform 1, the top of the first branch is rotationally matched with the first moving platform 2, and the plurality of first branches are evenly arranged around the center of the frame fixed platform 1; the second reconfigurable parallel robot includes: a second moving platform 3, a passive branch and a plurality of second branches, the two ends of the passive branch are respectively connected to the first moving platform 2 and the second moving platform 3; the second branch is arranged corresponding to the first branch, the bottom of the second branch is installed on the first branch, and the top of the second branch is rotationally matched with the second moving platform 3.

[0054] The present application can achieve different three-degree-of-freedom motion outputs by installing the second reconfigurable parallel robot on the first foldable mobile parallel robot. It can be used for the grinding processing of large deep-cavity variable-diameter parts 4. It has the advantages of high precision / rigidity and strong load capacity, and can achieve efficient grinding of large deep-cavity parts under different inner diameters.

[0055] like Figure 5 As shown, the first branch includes three branches; the first branch includes a first bearing seat 11, a second bearing seat 12, a first rotation pair 13, a first connecting rod 14, a second rotation pair 15, a second connecting rod 16 and a third rotation pair 17. The first bearing seat 11 and the second bearing seat 12 are fastened and mounted on the frame fixed platform 1. The first bearing seat 11 and the second bearing seat 12 are rotationally matched with the first connecting rod 14 through the first rotation pair 13. The first moving pair is rotationally matched with the first connecting rod 14 through the first rotation pair 13. The first connecting rod 14 is rotationally matched with the second connecting rod 16 through the second rotation pair 15. The second connecting rod 16 is rotationally matched with the first moving platform 2 through the third rotation pair 17. The rotation axes of the first rotation pair 13, the second rotation pair 15 and the third rotation pair 17 are all parallel to each other.

[0056] The first rotation pair 13 is a driving pair. A driver including a motor and a gear is installed on the first rotation pair 13. Through the driving motor, the first foldable mobile parallel robot can realize a movement perpendicular to the horizontal plane, and the second reconfigurable parallel robot can enter / exit the large part cavity.

[0057] like Figure 6 As shown, the second branch includes a first movable pair, a first ball joint 23, a third connecting rod 24 and a second ball joint 25. The first movable pair is installed on the second connecting rod 16. The first movable pair is rotationally matched with the third connecting rod 24 through the first ball joint 23, and the third connecting rod 24 is rotationally matched with the second movable platform 3 through the second ball joint 25.

[0058] The first movable sub-rail includes a first movable sub-rail 21 and a first movable sub-slider 22. The first movable sub-slider 22 is installed on the first movable sub-rail 21, and the two are slidably matched; the first movable sub-rail 21 is fastened on the second connecting rod 16, and the first movable sub-slider 22 is connected to the first ball joint 23 and rotates together.

[0059] like Figure 7 As shown, the passive branch includes a bearing seat, a Hooke's hinge and a second moving pair, and the two ends of the second moving pair are respectively rotatably matched with the bearing seat through the Hooke's hinge, and the two bearing seats are respectively fastened and installed on the top of the first moving platform 2 and the bottom of the second moving platform 3. The bearing seat includes a first bearing seat 31, a second bearing seat 32, a third bearing seat 33 and a fourth bearing seat 34.

[0060] The second moving pair includes a first passive rod 311 and a second passive rod 312 which are arranged vertically. The first passive rod 311 and the second passive rod 312 cooperate to form a second moving pair. The Hooke's hinge includes a first Hooke's hinge 39 and a second Hooke's hinge 310. The first Hooke's hinge 39 includes a first rotating shaft 313 and a second rotating shaft 314. The first rotating shaft 313 cooperates with a bearing seat to form a rotating pair. The first rotating shaft 313 cooperates with a first bearing seat 31 and a second bearing seat 32 installed on the first moving platform 2 to form a rotating pair; the second rotating shaft 314 is connected to the first passive rod 311. The axes of the second rotating shaft 314, the first rotating shaft 313 and the second moving pair are arranged perpendicular to each other.

[0061] The second Hooke's joint 310 includes a first rotating shaft 315 and a second rotating shaft 316. The first rotating shaft 315 cooperates with the bearing seat to form a rotating pair. The first rotating shaft 315 cooperates with the third bearing seat 33 and the fourth bearing seat 34 installed on the second moving platform 2 to form a rotating pair. The second rotating shaft 316 is connected to the second passive rod 312. The axes of the second rotating shaft 316, the first rotating shaft 315 and the second moving pair are arranged perpendicular to each other.

[0062] The passive branch also includes a limit locking device, which is used to respectively control the locking or release of the second rotating shaft 314, the first rotating shaft 313, the second rotating shaft 316, and the first rotating shaft 315. The limit locking device includes a first limit locking device 35, a second limit locking device 36, a third limit locking device 37, and a fourth limit locking device 38.

[0063] The first limit locking device 35 includes a first small limit motor 351, a first active limit rod 352 and a first limit ring 353; the first small limit motor 351 is fixedly connected to the side of the second bearing seat 32; the first limit ring 353 is fixedly connected to the first rotating shaft 313, and the center axis coincides with the axis of the first rotating shaft 313; the first active limit rod 352 is connected to the first small limit motor 351, and can move up and down by driving the first small limit motor 351 to achieve locking or releasing of the first rotating shaft 313.

[0064] The second limit locking device 36 includes a second small limit motor 361, a second active limit rod 362 and a second limit ring 363; the second small limit motor 361 is fixedly connected to the side of the first passive rod 311; the second limit ring 363 is fixedly connected to the second rotating shaft 314, and the center axis coincides with the axis of the second rotating shaft 314; the second active limit rod 362 is connected to the second small limit motor 361, and can move up and down by driving the second small limit motor 361 to achieve locking or releasing of the second rotating shaft 314.

[0065] The third limit locking device 37 includes a third small limit motor 371, a third active limit rod 372 and a third limit ring 373; the third small limit motor 371 is fixedly connected to the side of the second passive rod 312; the third limit ring 373 is fixedly connected to the second rotating shaft 316, and the center axis coincides with the axis of the second rotating shaft 316; the third active limit rod 372 is connected to the third small limit motor 371, and can move up and down by driving the third small limit motor 371 to achieve locking or release of the second rotating shaft 316.

[0066] The fourth limit locking device 38 includes a fourth small limit motor 381, a fourth active limit rod 382 and a fourth limit ring 383; the fourth small limit motor 381 is fixedly connected to the side of the fourth bearing seat 34; the fourth limit ring 383 is fixedly connected to the first rotating shaft 315, and the center axis coincides with the axis of the first rotating shaft 315; the fourth active limit rod 382 is connected to the fourth small limit motor 381, and can move up and down by driving the fourth small limit motor 381 to achieve locking or release of the first rotating shaft 315.

[0067] The first moving pair includes a driving pair, and the driving mechanism of the driving pair includes a ball screw mechanism driven by a motor. The second moving pair is a passive pair.

[0068] When the driving pair moves, the first limit locking device 35 and the second limit locking device 36 respectively lock the first rotation axis 313 and the second rotation axis 314 of the first Hooke's joint 39, and the parallel robot can output two rotations and one translation three-degree-of-freedom motion, which are respectively rotation around the axis of the first rotation axis 315 of the second Hooke's joint 310, rotation around the axis of the second rotation axis 316 of the second Hooke's joint 310, and movement along the second moving pair. When the driving pair moves, the first limit locking device 35 and the third limit locking device 37 respectively lock the first rotation axis 313 of the first Hooke's joint 39 and the second rotation axis 316 of the second Hooke's joint 310, and the parallel robot can output two rotations and one translation three-degree-of-freedom motion, which are respectively rotation around the axis of the second rotation axis 314 of the first Hooke's joint 39, rotation around the axis of the first rotation axis 315 of the second Hooke's joint 310, and movement along the second moving pair. When the driving pair moves, the second limit locking device 36 and the fourth limit locking device 38 respectively lock the second rotation axis 314 of the first Hooke's joint 39 and the first rotation axis 315 of the second Hooke's joint 310, and the parallel robot can output two rotations and one translation three-degree-of-freedom motion, which are respectively rotation around the axis of the first rotation axis 313 of the first Hooke's joint 39, rotation around the axis of the second rotation axis 316 of the second Hooke's joint 310, and movement along the second translation pair. When the driving pair moves, the third limit locking device 37 and the fourth limit locking device 38 respectively lock the first rotation axis 315 and the second rotation axis 316 of the second Hooke's joint 310, and the parallel robot can output two rotations and one translation three-degree-of-freedom motion, which are respectively rotation around the axis of the first rotation axis 313 of the first Hooke's joint 39, rotation around the axis of the second rotation axis 314 of the first Hooke's joint 39, and movement along the second translation pair.

[0069] In response to changes in the inner diameter, the terminal output freedom can be adjusted through the above-mentioned limit locking device.

[0070] The present application is formed by a frame fixed platform 1, a first moving platform 2, a second moving platform 3 and a plurality of branches connected in parallel, and has the advantages of compact structure, high precision, good rigidity, etc., and can be widely used in the fields of material sorting and handling, mechanical processing, etc. The present application can move according to a given degree of freedom by driving each branch, and can also change the terminal output motion by locking the drive motor or using a limit locking device to adapt to different scenarios. The present application can achieve different three-degree-of-freedom motion outputs and complete grinding according to the different inner diameters of deep-cavity variable-diameter parts 4, and has the advantages of strong adaptability to inner diameter changes.

[0071] How it works

[0072] When the driving pair moves, the first limit locking device 35 and the second limit locking device 36 respectively lock the first rotation axis 313 and the second rotation axis 314 of the first Hooke's joint 39, and the parallel robot can output two rotations and one translation three-degree-of-freedom motion, which are respectively rotation around the axis of the first rotation axis 315 of the second Hooke's joint 310, rotation around the axis of the second rotation axis 316 of the second Hooke's joint 310, and movement along the second moving pair. When the driving pair moves, the first limit locking device 35 and the third limit locking device 37 respectively lock the first rotation axis 313 of the first Hooke's joint 39 and the second rotation axis 316 of the second Hooke's joint 310, and the parallel robot can output two rotations and one translation three-degree-of-freedom motion, which are respectively rotation around the axis of the second rotation axis 314 of the first Hooke's joint 39, rotation around the axis of the first rotation axis 315 of the second Hooke's joint 310, and movement along the second moving pair. When the driving pair moves, the second limit locking device 36 and the fourth limit locking device 38 respectively lock the second rotation axis 314 of the first Hooke's joint 39 and the first rotation axis 315 of the second Hooke's joint 310, and the parallel robot can output two rotations and one translation three-degree-of-freedom motion, which are respectively rotation around the axis of the first rotation axis 313 of the first Hooke's joint 39, rotation around the axis of the second rotation axis 316 of the second Hooke's joint 310, and movement along the second translation pair. When the driving pair moves, the third limit locking device 37 and the fourth limit locking device 38 respectively lock the first rotation axis 315 and the second rotation axis 316 of the second Hooke's joint 310, and the parallel robot can output two rotations and one translation three-degree-of-freedom motion, which are respectively rotation around the axis of the first rotation axis 313 of the first Hooke's joint 39, rotation around the axis of the second rotation axis 314 of the first Hooke's joint 39, and movement along the second translation pair.

[0073] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0074] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A foldable reconfigurable parallel robot for grinding the inner wall of large deep cavity parts, characterized in that: It includes a first foldable mobile parallel robot and a second reconfigurable parallel robot; The first foldable mobile parallel robot comprises a frame fixed platform (1), a first moving platform (2) and a plurality of first branches, the first branches comprising a plurality of mutually cooperating rotation pairs, the bottom of the first branch being rotationally cooperating with the frame fixed platform (1), the top of the first branch being rotationally cooperating with the first moving platform (2), and the plurality of first branches being evenly arranged around the center of the frame fixed platform (1); The second reconfigurable parallel robot comprises: a second moving platform (3), a passive branch, and a plurality of second branches, wherein two ends of the passive branch are respectively connected to the first moving platform (2) and the second moving platform (3); The second branch is arranged corresponding to the first branch, the bottom of the second branch is mounted on the first branch, and the top of the second branch is rotatably matched with the second moving platform (3); The first branch includes three branches; The first branch comprises a first bearing seat (11), a second bearing seat (12), a first rotating pair (13), a first connecting rod (14), a second rotating pair (15), a second connecting rod (16) and a third rotating pair (17); the first bearing seat (11) and the second bearing seat (12) are fixedly mounted on the frame fixed platform (1); the first bearing seat (11) and the second bearing seat (12) are rotationally engaged with the first connecting rod (14) via the first rotating pair (13); the first moving pair is rotationally engaged with the first connecting rod (14) via the first rotating pair (13); the first connecting rod (14) is rotationally engaged with the second connecting rod (16) via the second rotating pair (15); and the second connecting rod (16) is rotationally engaged with the first moving platform (2) via the third rotating pair (17); The passive branch comprises a bearing seat, a Hooke's hinge and a second movable pair, the two ends of the second movable pair are respectively rotatably matched with the bearing seat through the Hooke's hinge, and the two bearing seats are respectively fastened and mounted on the top of the first movable platform (2) and the bottom of the second movable platform (3); The second branch comprises a first movable pair, a first ball joint (23), a third connecting rod (24) and a second ball joint (25); the first movable pair is mounted on the second connecting rod (16); the first movable pair is rotationally engaged with the third connecting rod (24) via the first ball joint (23); the third connecting rod (24) is rotationally engaged with the second movable platform (3) via the second ball joint (25); The second moving pair comprises a first passive rod (311) and a second passive rod (312) which are arranged vertically; The Hooke's hinge comprises a first Hooke's hinge (39) and a second Hooke's hinge (310); The first Hooke's hinge (39) comprises a first rotating shaft (313) and a second rotating shaft (314), the first rotating shaft (313) cooperates with the bearing seat to form a rotating pair, and the second rotating shaft (314) is connected to the first passive rod (311); The second Hooke's hinge (310) comprises a first rotating shaft (315) and a second rotating shaft (316), the first rotating shaft (315) cooperates with the bearing seat to form a rotating pair, and the second rotating shaft (316) is connected to the second passive rod (312); The passive branch further comprises a limit locking device, which is used to respectively control the locking or releasing of the second rotating shaft (314), the first rotating shaft (313), the second rotating shaft (316), and the first rotating shaft (315).

2. The foldable reconfigurable parallel robot for inner wall grinding of large deep cavity parts according to claim 1, characterized in that: The rotation axes of the first rotation pair (13), the second rotation pair (15) and the third rotation pair (17) are all parallel to each other.

3. The foldable reconfigurable parallel robot for inner wall grinding of large deep cavity parts according to claim 1, characterized in that: The first movable pair comprises a first movable pair guide rail (21) and a first movable pair slider (22), the first movable pair slider (22) being mounted on the first movable pair guide rail (21), and the two are slidably matched; The first movable auxiliary guide rail (21) is fixedly mounted on the second connecting rod (16), and the first movable auxiliary sliding block (22) is connected to the first ball joint (23) and is rotationally matched.

4. The foldable reconfigurable parallel robot for inner wall grinding of large deep cavity parts according to claim 1, characterized in that: The first rotating pair (13) comprises a driving pair, a driver is mounted on the first rotating pair (13), and the driver comprises a motor and a gear driver; The first moving pair includes a driving pair, and the driving mechanism of the first moving pair includes a ball screw mechanism driven by a motor.

5. The foldable reconfigurable parallel robot for inner wall grinding of large deep cavity parts according to claim 1, characterized in that: The axes of the second rotating shaft (314), the first rotating shaft (313) and the second moving pair are arranged perpendicular to each other; The axes of the second rotating shaft (316), the first rotating shaft (315) and the second moving pair are arranged perpendicular to each other.

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