Crown block and material taking and placing method thereof

Abstract

The invention discloses a crown block and a material taking and placing method thereof. The crown block comprises a frame assembly, a walking mechanism, a first lifting mechanism, a first transverse moving mechanism connected with the first lifting mechanism, a second lifting mechanism connected with the first transverse moving mechanism and a gripper mechanism connected with the second lifting mechanism, and the walking mechanism is installed on the frame assembly and used for driving the whole crown block to run in the X direction. The first lifting mechanism is connected to the lower portion of the frame assembly to drive the first transverse moving mechanism, the second lifting mechanism and the gripper mechanism to move in the Z direction, the first transverse moving mechanism is used for driving the second lifting mechanism and the gripper mechanism to move in the Y direction, and the second lifting mechanism is used for driving the gripper mechanism to move in the Z direction to take and place objects. According to the scheme, a crown block can directly take and place materials from the embedded Prot port, traditional NTB / AMR / AGV equipment is replaced, and cost and workshop ground space are saved.

Description

Technical Field

[0001] The invention relates to the technical field of automatic handling equipment, in particular to an overhead crane and a material taking and placing method thereof. Background Art

[0002] In the semiconductor manufacturing process, an overhead crane is usually used to transfer wafer boxes for carrying wafers between different workstations. Specifically, the overhead crane runs on the overhead rail to the designated port (pick-up and place port), and the lifting mechanism of the overhead crane drives the pick-up and place mechanism to descend to grab the wafer box at the port or release the wafer box at the port, and then the lifting mechanism drives the pick-up and place mechanism to rise.

[0003] The Chinese patent application with publication number CN117727671A discloses a crane, which includes a frame assembly, a travel drive mechanism arranged on the frame assembly, a traverse mechanism connected to the frame assembly, and a gripping mechanism connected to the traverse mechanism, wherein the gripping mechanism includes a lifting assembly, a rotating assembly, and a gripping assembly. When it is necessary to pick up and place the wafer box, the traverse mechanism extends the gripping mechanism, the lifting assembly drives the rotating assembly and the gripping assembly to descend, the rotating assembly drives the gripping assembly to rotate to a preset position, and then the wafer box is picked up and placed. This type of crane can only pick up and place materials for the Port port arranged on the outside or the open Port port. When the Port port of the equipment in the wafer factory is embedded (i.e., there is an obstruction above the Port port), it is necessary to load the wafer box through an in-depth robot such as NTB (Near Tool Buffer) / AMR / AGV, and push the wafer box into the Port port. The setting of the in-depth robot equipment not only increases the cost, but also increases the space occupied by the equipment. Summary of the invention

[0004] In order to overcome the defects in the prior art, an embodiment of the present invention provides an overhead crane and a material loading and unloading method thereof, which can enable the overhead crane to directly load and unload materials from an embedded Port, replacing traditional NTB / AMR / AGV equipment, saving costs and workshop floor space.

[0005] The embodiment of the present application discloses: an overhead crane, comprising: a frame assembly, a traveling mechanism, a first lifting mechanism, a first transverse movement mechanism connected to the first lifting mechanism, a second lifting mechanism connected to the first transverse movement mechanism, and a gripper mechanism connected to the second lifting mechanism, wherein the traveling mechanism is installed on the frame assembly and is used to drive the entire overhead crane to move along the X direction, the first lifting mechanism is connected to the bottom of the frame assembly to drive the first transverse movement mechanism, the second lifting mechanism and the gripper mechanism to move along the Z direction, the first transverse movement mechanism is used to drive the second lifting mechanism and the gripper mechanism to move along the Y direction, and the second lifting mechanism is used to drive the gripper mechanism to move along the Z direction to pick up and place items.

[0006] Specifically, the second lifting mechanism includes a first motor, a first pulley, a first belt, a first screw rod and a second pulley, the first motor is connected to the first transverse movement mechanism, the first pulley is connected to the output shaft of the first motor, the first screw rod is rotatably connected to the first transverse movement mechanism, the inner ring of the second pulley is connected to the first screw rod, the outer ring of the second pulley is connected to the first pulley through the first belt, and the gripping mechanism is connected to the first screw rod through the first nut seat.

[0007] Specifically, the second lifting mechanism also includes a third pulley, a second screw rod, a fourth pulley and a second belt, the third pulley is installed on the first screw rod, the second screw rod is rotatably connected to the first transverse movement mechanism, the inner ring of the fourth pulley is connected to the second screw rod, the outer ring of the fourth pulley is connected to the third pulley through the second belt, and the gripping mechanism is connected to the second screw rod through a second nut seat.

[0008] Specifically, the second lifting mechanism further includes at least one guide rod fixed on the first transverse movement mechanism, and the gripping mechanism is slidably connected to the guide rod.

[0009] Specifically, the gripper mechanism includes a first mounting plate, a first screw motor, a third nut seat and two grippers. The first mounting plate is connected to the second lifting mechanism. The first screw motor is installed on the first mounting plate. The two grippers are connected to the screw of the first screw motor through the third nut seat. The first screw motor is used to drive the two grippers to move toward and away from each other.

[0010] Specifically, the gripper includes a connecting plate and a clamping plate, one end of the connecting plate is connected to the third nut seat, and the other end of the connecting plate is provided with a long hole, the axis of the long hole is not parallel to the screw axis of the first screw motor, and the clamping plate is connected to the connecting plate through a cam follower arranged in the long hole, and the clamping plate is also connected to the slide rail on the first mounting plate through a slide seat.

[0011] Specifically, the overhead crane also includes a second transverse movement mechanism, which is connected to the bottom of the frame assembly, and the first lifting mechanism is connected to the second transverse movement mechanism and can move along the Y direction under the drive of the second transverse movement mechanism.

[0012] Specifically, the overhead crane also includes a rotating mechanism disposed between the second transverse movement mechanism and the first lifting mechanism, the rotating mechanism is connected below the second transverse movement mechanism, the first lifting mechanism is connected below the rotating mechanism, and the rotating mechanism is used to drive the first lifting mechanism to rotate.

[0013] The present application also discloses: a material loading and unloading method of an overhead crane as described in the present embodiment, comprising the following steps:

[0014] Step 1: The overhead crane stops at the corresponding position of the overhead rail;

[0015] Step 2: The second transverse movement mechanism drives the first lifting mechanism to move along the Y direction to the first preset position;

[0016] Step 3: The first lifting mechanism drives the first transverse movement mechanism to descend to a second preset position;

[0017] Step 4: The first transverse movement mechanism drives the second lifting mechanism and the gripper mechanism to move along the Y direction to the third preset position;

[0018] Step 5: The second lifting mechanism drives the gripper mechanism to descend to the fourth preset position to grab or release the object.

[0019] The present application also discloses: a material loading and unloading method of an overhead crane as described in the present embodiment, comprising the following steps:

[0020] Step 1: The first transverse movement mechanism drives the gripper mechanism to move along the Y direction to the fifth preset position;

[0021] Step 2: The second transverse movement mechanism performs stroke compensation on the gripper mechanism along the Y direction, so that the gripper mechanism moves to the sixth preset position;

[0022] Step 3: The second lifting mechanism drives the gripper mechanism to descend to the seventh preset position to grab or release the object.

[0023] The present invention has at least the following beneficial effects:

[0024] The overhead crane of this embodiment is provided with a second lifting mechanism connected to the first transverse movement mechanism to adjust the height of the gripper mechanism for the second time. When it is necessary to pick up and place materials at the embedded port, the other mechanisms installed thereon are first lowered as a whole to a position corresponding to the height of the port through the first lifting mechanism, and then the second lifting assembly and the gripper assembly are driven to the top of the pick-up and place platform of the port along the X direction through the first transverse movement assembly, and then the gripper assembly is driven by the second lifting mechanism to descend to the place platform to pick up and place materials. In this way, the traditional NTB / AMR / AGV and other deep-seated robots can be replaced to load the wafer box, saving equipment costs and saving floor space in the workshop.

[0025] 2. The first transverse movement mechanism of this embodiment is connected to the bottom of the first lifting mechanism. In other words, the first transverse movement mechanism does not need to bear the weight of the first lifting mechanism. Therefore, the load of the first transverse movement mechanism is reduced and the telescopic stability of the first transverse movement mechanism is improved.

[0026] 3. The second transverse movement mechanism of this embodiment can compensate the stroke of the gripper mechanism within a small range along the Y direction with high compensation accuracy, which can improve the alignment accuracy between the object and the pick-and-place platform.

[0027] In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 is a schematic structural diagram of an overhead travelling crane in an embodiment of the present invention;

[0030] Figure 2 It is a structural schematic diagram of a second lifting mechanism and a gripping mechanism connected to a first transverse movement mechanism in an embodiment of the present invention;

[0031] Figure 3 is a schematic structural diagram of a second lifting mechanism in an embodiment of the present invention;

[0032] Figure 4 is a schematic structural diagram of a gripper mechanism in an embodiment of the present invention;

[0033] Figure 5 is a schematic diagram of the connection between the second transverse movement mechanism, the first lifting mechanism and the rotating mechanism in an embodiment of the present invention;

[0034] Figure 6 It is a schematic diagram of the connection between the first lifting mechanism and the rotating mechanism in an embodiment of the present invention.

[0035] The reference numerals of the above drawings are: 1, frame assembly; 11, first frame; 12, second frame; 13, top platform; 2, walking mechanism; 3, first lifting mechanism; 4, first transverse mechanism; 41, second mounting plate; 42, third screw motor; 431, first transverse plate; 432, second transverse plate; 433, third transverse plate; 44, fifth pulley; 45, third belt; 46, fifth nut seat; 5, second lifting mechanism; 51, first motor; 52, first pulley; 53, first belt; 54, first screw; 5 5. Second pulley; 56. First nut seat; 57. Third pulley; 58. Second screw; 59. Fourth pulley; 510. Second belt; 511. Second nut seat; 512. Guide rod; 6. Gripping mechanism; 61. First mounting plate; 62. First screw motor; 63. Third nut seat; 64. Connecting plate; 641. Long hole; 65. Clamping plate; 66. Cam follower; 7. Second transverse mechanism; 71. Second screw motor; 72. Fourth nut seat; 8. Rotating mechanism; 9. Anti-falling mechanism; 10. Objects. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "fixed", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood by specific circumstances.

[0038] In the present invention, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may include the first feature and the second feature being in direct contact, or may include the first feature and the second feature being in contact not directly but through another feature between them. Moreover, a first feature being “above”, “below”, and “above” a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature includes the first feature being below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0039] In the description of this embodiment, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship 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 device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the scope of protection of the present application.

[0040] In addition, the terms "first", "second", etc. are only used to distinguish in description and have no special meaning.

[0041] like Figure 1 and Figure 2 As shown, the overhead travelling vehicle of this embodiment mainly comprises: a frame assembly 1, a traveling mechanism 2, a first lifting mechanism 3, a first transverse mechanism 4, a second lifting mechanism 5 and a gripping mechanism 6. Among them, the frame assembly 1 is used as the main body of the overhead travelling vehicle for supporting and installing the above-mentioned mechanisms. The frame assembly 1 comprises a first frame 11 and a second frame 12 which are arranged relatively, and a top platform 13 for connecting the first frame 11 and the second frame 12; the traveling mechanism 2 is installed on the top platform 13, and is used to drive the overhead travelling vehicle as a whole to run along the X direction (the direction in which the overhead rail extends); the first lifting mechanism 3 is connected to the bottom of the top platform 13, the first transverse mechanism 4 is connected to the first lifting mechanism 3 and is located below the first lifting mechanism 3, the second lifting mechanism 5 is connected to the first transverse mechanism, and the gripping mechanism 6 is connected to the second lifting mechanism 5. The first lifting mechanism 3 is used to drive the first transverse movement mechanism 4, the second lifting mechanism 5 and the gripping mechanism 6 to lift and lower along the Z direction; the first transverse movement mechanism 4 is used to drive the second lifting mechanism 5 and the gripping mechanism 6 to move along the Y direction; the second lifting mechanism 5 is used to drive the gripping mechanism 6 to lift and lower along the Z direction to pick up and place the object 10.

[0042] The overhead crane in the above scheme performs a second height adjustment on the gripper mechanism 6 by setting a second lifting mechanism 5 connected to the first transverse movement mechanism 4. When it is necessary to pick up and place materials at the embedded Prot port, the other mechanisms installed thereon are first lowered as a whole to a position corresponding to the height of the Prot port through the first lifting mechanism 3, and then the second lifting assembly and the gripper assembly are driven along the X direction to the top of the picking and placing platform of the Prot port through the first transverse movement assembly, and then the second lifting mechanism 5 drives the gripper assembly to descend to the placing platform to pick up and place materials. In this way, it can replace the traditional NTB / AMR / AGV and other in-depth robots to load the wafer box, saving equipment costs and saving floor space in the workshop.

[0043] like Figure 3As shown, the second lifting mechanism 5 of this embodiment includes a first motor 51, a first pulley 52, a first belt 53, a first screw 54 and a second pulley 55. Among them, the first motor 51 is installed on the first transverse mechanism 4, the first pulley 52 is connected to the output shaft of the first motor 51; the first screw 54 is rotatably connected to the first transverse mechanism 4, the inner ring of the second pulley 55 is fixedly connected to the first screw 54, and the outer ring of the second pulley 55 is connected to the first pulley 52 on the first motor 51 through the first belt 53; the gripping mechanism 6 is movably connected to the first screw 54 through the first nut seat 56. When the first motor 51 is started, the first pulley 52 rotates with its output shaft, driving the second pulley 55 and the first screw 54 to rotate, so that the first nut seat 56 drives the gripping mechanism 6 to move up and down along the axial direction of the first screw 54, realizing the lifting and lowering of the gripping mechanism 6.

[0044] like Figure 3 As shown, the second lifting mechanism 5 of this embodiment also includes a third pulley 57, a second screw rod 58, a fourth pulley 59 and a second belt 510. Among them, the third pulley 57 is installed on the first screw rod 54, the second screw rod 58 is rotatably connected to the first transverse mechanism 4, the inner ring of the fourth pulley 59 is fixedly connected to the second screw rod 58, the outer ring of the fourth pulley 59 is connected to the third pulley 57 through the second belt 510, and the gripping mechanism 6 is movably connected to the second screw rod 58 through the second nut seat 511. When the first motor 51 is started, the first pulley 52 rotates to drive the second pulley 55, the first screw rod 54 and the third pulley 57 to rotate, and the second belt 510 drives the fourth pulley 59 and the second screw rod 58 to rotate, so that the second nut seat 511 drives the gripping mechanism 6 to move up and down along the axial direction of the second screw rod 58. By adopting the above scheme, the gripping mechanism 6 is connected to the first screw rod 54 through the first nut seat 56 and to the second screw rod 58 through the second nut seat 511, which can improve the stability of the second lifting mechanism 5 driving the gripping mechanism 6 to move up and down; the first screw rod 54 and the second screw rod 58 are connected by the second belt 510, which can reduce the number of driving motors and ensure the consistency of the movement of the first nut seat 56 and the second nut seat 511.

[0045] like Figure 2 and Figure 3 As shown, the second lifting mechanism 5 of this embodiment further includes at least one guide rod 512 , which is fixed on the first transverse movement mechanism 4 and penetrates the gripping mechanism 6 , and the gripping mechanism 6 is slidably connected to the guide rod 512 .

[0046] like Figure 4As shown, the gripper mechanism 6 of this embodiment mainly includes a first mounting plate 61, a first screw motor 62, a third nut seat 63 and two grippers. Among them, the first mounting plate 61 is used to connect with the first nut seat 56 and the second nut seat 511 of the second lifting mechanism 5, and the first mounting plate 61 is also connected with the guide rod 512; the first screw motor 62 is installed on the first mounting plate 61, and the third nut seat 63 is movably connected to its screw rod, and the two grippers are connected to the screw rod of the first screw motor 62 through the third nut seat 63, and the two grippers are relatively arranged on both sides of the third nut seat 63. When the first screw motor 62 is started, the third nut seat 63 moves linearly along the screw rod axial direction of the first screw motor 62, driving the two grippers to move toward or away from each other, so as to achieve the clamping or release of the object 10.

[0047] like Figure 4 As shown, the gripper of this embodiment includes a connecting plate 64 and a clamping plate 65. One end of the connecting plate 64 is connected to the third nut seat 63, and the other end of the connecting plate 64 is provided with an elongated hole 641, the axis of which is not parallel to the axis of the screw of the first screw motor 62. A cam follower 66 is connected to the clamping plate 65, and the cam follower 66 is inserted into the elongated hole 641 of the connecting plate 64 to realize the movable connection between the clamping plate 65 and the connecting plate 64. The clamping plate 65 is also connected to the slide rail on the first mounting plate 61 through a slide seat, so that the movement of the clamping plate 65 can be restricted, so that the clamping plate 65 can only move in a direction perpendicular to the screw of the first screw motor 62, and the clamping plate 65 is prevented from moving in a direction parallel to the screw of the first screw motor 62.

[0048] like Figure 1 and Figure 5 As shown, the overhead travelling crane of this embodiment further includes a second transverse movement mechanism 7. The second transverse movement mechanism 7 is connected to the bottom of the top platform 13 of the frame assembly 1, and the first lifting mechanism 3 is connected to the second transverse movement mechanism 7 and can move along the Y direction under the drive of the second transverse movement mechanism 7. Specifically, the second transverse movement mechanism 7 may include a second screw motor 71 and a fourth nut seat 72, the second screw motor 71 is fixed to the bottom of the top platform 13, and the fourth nut seat 72 is used to connect the screw of the second screw motor 71 and the first lifting mechanism 3. The second transverse movement mechanism 7 can be used to compensate the stroke of the gripper assembly within a small range, thereby improving the alignment accuracy of the object 10 and the discharge platform.

[0049] like Figure 5 and Figure 6As shown, the overhead travelling crane of this embodiment further includes a rotating mechanism 8 disposed between the second transverse moving mechanism 7 and the first lifting mechanism 3. The rotating mechanism 8 is connected to the lower part of the second transverse moving mechanism 7, and the first lifting mechanism 3 is connected to the lower part of the rotating mechanism 8. The rotating mechanism 8 is used to drive the first lifting mechanism 3 and other mechanisms installed thereon to rotate, and can drive the gripping mechanism 6 to rotate at a small angle of 0 to 6 degrees, so as to have a certain tolerance for the uneven placement of items 10 such as wafer equipment.

[0050] like Figure 2 As shown, the first transverse mechanism 4 of this embodiment is a three-stage transverse mechanism. In other words, the first transverse mechanism 4 includes three transverse plates that can move along the Y direction and a driving motor and a transmission structure for driving the three transverse plates to move. Specifically, the first transverse mechanism 4 includes a second mounting plate 41, a third screw motor 42, a first transverse plate 431, a second transverse plate 432 and a third transverse plate 433. The second mounting plate 41 is used to connect with the first lifting mechanism 3. The third screw motor 42 is installed on the second mounting plate 41. Two fifth pulleys 44 are connected to the first transverse plate 431. The two fifth pulleys 44 are connected through a third belt 45. The third belt 45 is connected to the fifth nut seat 46 on the third screw motor 42. The second transverse plate 432 is connected to the first transverse plate 431 and the third transverse plate 433 through a transmission mechanism. When the third screw motor 42 is started, it can drive the first transverse plate 431, the second transverse plate 432 and the third transverse plate 433 to move along the Y direction. By adopting the above solution, the first transverse movement mechanism 4 can realize a large-scale transverse movement of the gripper mechanism 6 along the Y direction, so as to meet the requirements of taking and placing materials of various embedded ports.

[0051] like Figure 1 As described above, the overhead travelling crane of this embodiment further comprises an anti-falling mechanism 9 arranged at the lower end of the frame assembly 1, and the anti-falling mechanism 9 is used to clamp the article 10 when transporting the article 10 to prevent the article 10 from falling.

[0052] The method of loading and unloading materials by the overhead crane of this embodiment for the embedded port is as follows:

[0053] Step 1: The overhead crane stops at the corresponding position of the overhead rail.

[0054] Step 2: The second transverse movement mechanism 7 drives the first lifting mechanism 3 to move along the Y direction to the first preset position.

[0055] Step 3: The first lifting mechanism 3 drives the first transverse movement mechanism 4 to descend to the second preset position.

[0056] Step 4: The first transverse movement mechanism 4 drives the second lifting mechanism 5 and the gripping mechanism 6 to move along the Y direction to the third preset position.

[0057] Step 5: The second lifting mechanism 5 drives the gripping mechanism 6 to descend to the fourth preset position to grab or release the object 10.

[0058] Step 6: The second lifting mechanism 5 lifts the gripping mechanism 6 to the origin position.

[0059] Step 7: The first transverse movement mechanism 4 drives the gripper mechanism 6 to reset along the Y direction.

[0060] Step 8: The first lifting mechanism 3 lifts the first transverse movement mechanism 4 and the gripper mechanism 6 to the origin in the vehicle body.

[0061] Step 9: The second transverse movement mechanism 7 drives the first lifting mechanism 3 to return to the origin.

[0062] Step 10: The anti-fall mechanism 9 is clamped (loading state).

[0063] The method of loading and unloading materials from the overhead buffer (OHB) of the overhead crane in this embodiment is as follows:

[0064] Step 1: The first transverse movement mechanism 4 drives the gripper mechanism 6 to move along the Y direction to the fifth preset position;

[0065] Step 2: The second transverse movement mechanism 7 performs stroke compensation on the gripper mechanism 6 along the Y direction (according to requirements), so that the gripper mechanism 6 moves to the sixth preset position;

[0066] Step 3: The second lifting mechanism 5 drives the gripping mechanism 6 to descend to the seventh preset position to grab or release the object 10.

[0067] Step 4: After the picking and placing is completed, the second lifting mechanism 5 drives the gripper mechanism 6 to rise back to the origin, and the second transverse movement mechanism 7 and the first transverse movement mechanism 4 move transversely back to the origin in sequence.

[0068] The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. An overhead crane, characterized in that: include: A frame assembly, a walking mechanism, a first lifting mechanism, a first transverse movement mechanism connected to the first lifting mechanism, a second lifting mechanism connected to the first transverse movement mechanism, and a gripper mechanism connected to the second lifting mechanism. The walking mechanism is installed on the frame assembly and is used to drive the entire overhead crane to move along the X direction. The first lifting mechanism is connected to the bottom of the frame assembly to drive the first transverse movement mechanism, the second lifting mechanism and the gripper mechanism to move along the Z direction. The first transverse movement mechanism is used to drive the second lifting mechanism and the gripper mechanism to move along the Y direction. The second lifting mechanism is used to drive the gripper mechanism to move along the Z direction to pick up and place items.

2. The overhead travelling crane according to claim 1, characterized in that: The second lifting mechanism includes a first motor, a first pulley, a first belt, a first screw rod and a second pulley. The first motor is connected to the first transverse movement mechanism, the first pulley is connected to the output shaft of the first motor, the first screw rod is rotatably connected to the first transverse movement mechanism, the inner ring of the second pulley is connected to the first screw rod, the outer ring of the second pulley is connected to the first pulley through the first belt, and the gripping mechanism is connected to the first screw rod through the first nut seat.

3. The overhead travelling crane according to claim 2, characterized in that: The second lifting mechanism also includes a third pulley, a second screw rod, a fourth pulley and a second belt, the third pulley is installed on the first screw rod, the second screw rod is rotatably connected to the first transverse movement mechanism, the inner ring of the fourth pulley is connected to the second screw rod, the outer ring of the fourth pulley is connected to the third pulley through the second belt, and the gripping mechanism is connected to the second screw rod through a second nut seat.

4. The overhead travelling crane according to claim 2, characterized in that: The second lifting mechanism further comprises at least one guide rod fixed on the first transverse movement mechanism, and the gripping mechanism is slidably connected to the guide rod.

5. The overhead travelling crane according to claim 1, characterized in that: The gripper mechanism includes a first mounting plate, a first screw motor, a third nut seat and two grippers. The first mounting plate is connected to the second lifting mechanism. The first screw motor is installed on the first mounting plate. The two grippers are connected to the screw of the first screw motor through the third nut seat. The first screw motor is used to drive the two grippers to move toward and away from each other.

6. The overhead travelling crane according to claim 5, characterized in that: The gripper includes a connecting plate and a clamping plate, one end of the connecting plate is connected to the third nut seat, and the other end of the connecting plate is provided with a long hole, the axis of the long hole is not parallel to the screw axis of the first screw motor, the clamping plate is connected to the connecting plate through a cam follower arranged in the long hole, and the clamping plate is also connected to the slide rail on the first mounting plate through a slide seat.

7. The overhead travelling crane according to claim 1, characterized in that: The overhead travelling crane further comprises a second transverse movement mechanism, wherein the second transverse movement mechanism is connected to the lower part of the frame assembly, and the first lifting mechanism is connected to the second transverse movement mechanism and can move along the Y direction under the drive of the second transverse movement mechanism.

8. The overhead travelling crane according to claim 7, characterized in that: The overhead travelling crane further comprises a rotating mechanism disposed between the second transverse moving mechanism and the first lifting mechanism, the rotating mechanism being connected below the second transverse moving mechanism, the first lifting mechanism being connected below the rotating mechanism, and the rotating mechanism being used to drive the first lifting mechanism to rotate.

9. A method for loading and unloading materials by an overhead crane according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1: The overhead crane stops at the corresponding position of the overhead rail; Step 2: The second transverse movement mechanism drives the first lifting mechanism to move along the Y direction to the first preset position; Step 3: The first lifting mechanism drives the first transverse movement mechanism to descend to a second preset position; Step 4: The first transverse movement mechanism drives the second lifting mechanism and the gripper mechanism to move along the Y direction to the third preset position; Step 5: The second lifting mechanism drives the gripper mechanism to descend to the fourth preset position to grab or release the object.

10. A material loading and unloading method for an overhead crane according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1: The first transverse movement mechanism drives the gripper mechanism to move along the Y direction to the fifth preset position; Step 2: The second transverse movement mechanism performs stroke compensation on the gripper mechanism along the Y direction, so that the gripper mechanism moves to the sixth preset position; Step 3: The second lifting mechanism drives the gripper mechanism to descend to the seventh preset position to grab or release the object.

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