Automated material handling apparatus and method

Abstract

An automatic material conveying device and method, the automatic material conveying device comprises a crown block, a bearing plate, a photoelectric sensing mechanism and a reflection mechanism. The photoelectric sensing mechanism is installed on the crown block. The reflection mechanism comprises a trigger part, a reflection plate and a transmission part, the reflection plate and the transmission part are located below the bearing plate, the trigger part is connected with the reflection plate through the transmission part, the trigger part can move up and down relative to the bearing plate, when the first surface of the bearing plate is free of material, one end of the trigger part protrudes from the first surface of the bearing plate, and the reflection plate is in a first position; when the first surface of the bearing plate has material, one end of the trigger part is pressed down by the material and moves downward, and the reflection plate is driven to move to a second position through the transmission part; when the reflection plate is in the first position, the reflection plate can receive light from the photoelectric sensing mechanism, and the photoelectric sensing mechanism generates a first signal; when the reflection plate is in the second position, the reflection plate cannot receive light from the photoelectric sensing mechanism, and the photoelectric sensing mechanism generates a second signal.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing, and in particular to an automated handling system used in the manufacturing of semiconductor integrated circuits. Background Technology

[0002] In semiconductor manufacturing, wafers need to be transferred between different processes. To avoid contamination or damage to the wafers, they are usually placed in wafer cassettes to carry them and facilitate the transfer.

[0003] Wafer transfer is typically achieved through an Automated Material Handling System (AMHS).

[0004] The automated material handling system includes an automated overhead hoist (OHT) and a support plate. The overhead hoist can move along tracks, and the support plate is located in the wafer cassette storage position.

[0005] Before placing a wafer cassette onto a carrier plate, the automated overhead crane needs to first confirm whether a wafer cassette already exists on the carrier plate. This is to avoid placing a wafer cassette again if one already exists on the carrier plate, which would result in a double loading. Summary of the Invention

[0006] To address the aforementioned issues, this invention provides an automated material handling device and method that can accurately detect the presence of a wafer cassette, preventing misjudgments even if no wafers are present in the cassette.

[0007] To achieve the above objectives, the present invention provides an automatic material handling device, including an overhead crane, a support plate, a photoelectric sensing mechanism, and a reflective mechanism.

[0008] The overhead crane is movably mounted on the crane track. A support plate is located below the overhead crane and has opposing first and second surfaces; the first surface is used to support materials. A photoelectric sensing mechanism is mounted on the overhead crane. The reflection mechanism includes a trigger, a reflector, and a transmission part. The reflector and transmission part are located below the support plate. The trigger and reflector are connected via the transmission part. The trigger can move up and down relative to the support plate. When there is no material on the first surface, one end of the trigger protrudes from the first surface of the support plate, and the reflector is in a first position. When there is material on the first surface of the support plate, one end of the trigger is pressed down by the material and moves downward, driving the reflector to a second position via the transmission part. When the reflector is in the first position, it can receive light from the photoelectric sensing mechanism and reflect it back to the photoelectric sensing mechanism, generating a first signal. When the reflector is in the second position, it cannot receive light from the photoelectric sensing mechanism, and the photoelectric sensing mechanism generates a second signal.

[0009] According to one embodiment, the transmission part includes a first engagement part and a second engagement part. The first engagement part is fixedly connected to the trigger part, and the second engagement part is connected to the reflector. The first engagement part and the second engagement part engage, and during the movement of the trigger part, the reflector can move between a first position and a second position through the transmission of the first engagement part and the second engagement part.

[0010] According to one embodiment, the first meshing part is a rack and the second meshing part is a gear.

[0011] According to one embodiment, the reflection mechanism further includes a mounting base, a connecting rod, and a bearing. The bearing is mounted on the connecting rod, and the reflector is rotatably connected to the mounting base via the connecting rod. The mounting base 44 is disposed on the second surface of the support plate, and the second engagement part is fixedly connected to the connecting rod. During the rotation of the second engagement part, the reflector can be driven to rotate between the first position and the second position.

[0012] According to one embodiment, one end of the first engaging part is fixedly connected to the other end of the triggering part and is coaxial with the triggering part. The reflection mechanism also includes a stop part, which is fixed to one end of the first engaging part. When the reflector is in the first position, the stop part abuts against the second surface.

[0013] According to one embodiment, the reflection mechanism further includes an elastic part connected to the trigger part. When the trigger part is not pressed down by an external force, the reflector is in a first position, and the elastic part is in a free state. When the trigger part is pressed down by an external force, the reflector is in a second position, and the elastic part deforms. After the external force is removed, the trigger part rises due to the elastic restoring force of the elastic part, causing the reflector to return to the first position. According to one embodiment, there is a pair of mounting seats, symmetrically arranged on opposite sides of the reflector, with the transmission part adjacent to one of the mounting seats.

[0014] According to one embodiment, when the reflector is in the first position, the reflector and the support plate are parallel to each other; when the reflector is in the second position, the angle between the reflector and the support plate is 80° to 100°.

[0015] According to one embodiment, when the reflector is in the first position, the reflector is in a horizontal position; when the reflector is in the second position, the reflector is perpendicular to the horizontal position.

[0016] According to one embodiment, when the reflector is in the second position, the reflector is in a vertical position.

[0017] According to one embodiment, the number of reflective mechanisms is one or more.

[0018] According to one embodiment, the number of reflective mechanisms is one, which is located below the center of the support plate.

[0019] According to one embodiment, there are multiple reflective mechanisms, which are evenly distributed below the center of the support plate.

[0020] According to one embodiment, the surface of the reflector has a reflective material.

[0021] According to one embodiment, the system further includes a control mechanism that is capable of controlling the crane's gripping mechanism to lower materials in response to the first signal, and capable of controlling the crane to move to the next lowering station in response to the second signal.

[0022] In another aspect, the present invention provides an automated material handling method, which is executed using the aforementioned automated material handling equipment, comprising:

[0023] The overhead crane moves to the top of the support plate of a workstation, and controls the crane's movement based on the signal emitted by the photoelectric sensing mechanism;

[0024] When the photoelectric sensing mechanism generates a first signal, it controls the crane's gripping mechanism to lower the material to the workstation.

[0025] When the photoelectric sensing mechanism generates a second signal, it controls the overhead crane to move to the next work station.

[0026] The advantages of this invention compared to existing technologies are as follows: the reflector of this invention can change its position based on whether a wafer cassette is present, thereby enabling the photoelectric sensing mechanism to generate a corresponding sensing signal. Compared to automated material handling systems in related technologies where the reflector is fixed, the automated material handling equipment of this invention can accurately sense the presence of a wafer cassette, and will not produce false alarms even if there are no wafers in the wafer cassette. Furthermore, this invention has a simple structure and is easy to implement. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of an automated material handling system in related technologies.

[0028] Figure 2 This is a top view of the support plate and reflector of an automated material handling system in related technologies.

[0029] Figure 3 This is a side view of the support plate and reflector of an automated material handling system in related technologies.

[0030] Figure 4 A schematic diagram of a dual-infeed sensor detecting a wafer cassette in an automated material handling system in related technologies.

[0031] Figure 5 This is a schematic diagram illustrating a false detection by a dual-entry sensor in an automated material handling system in related technologies.

[0032] Figure 6 This is a schematic diagram of an automated material handling device according to an embodiment of the present disclosure.

[0033] Figure 7 This is a schematic diagram of an automated material handling device according to an embodiment of the present disclosure, wherein the reflector is in the first position.

[0034] Figure 8 This is a schematic diagram of an automated material handling device according to an embodiment of the present disclosure, wherein the reflector is in the second position.

[0035] Figure 9 This is a top view of the support plate and reflector of an automated material handling device according to an embodiment of the present disclosure, wherein the reflector is in a first position.

[0036] Figure 10 This is a side view of the support plate and reflector of an automated material handling device according to an embodiment of the present disclosure, wherein the reflector is in a first position.

[0037] Figure 11 This is a side view of the support plate and reflector of an automated material handling device according to an embodiment of the present disclosure, wherein the reflector is in a second position.

[0038] Figure 12 for Figure 10 A magnified view of part A in the middle.

[0039] Figure 13 for Figure 11 A magnified view of part B in the middle section.

[0040] Figure 14 This is a flowchart of an automated material handling method. Detailed Implementation

[0041] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided to make the invention more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. In the drawings, the thickness of regions and layers may be exaggerated for clarity. The same reference numerals in the drawings denote the same or similar structures, and therefore their detailed descriptions will be omitted.

[0042] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a full understanding of embodiments of the invention. However, those skilled in the art will recognize that the technical solutions of the invention can be practiced without one or more of the specific details described, or other methods, components, materials, etc., can be employed. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring the main technical concept of the invention.

[0043] In related technologies, to avoid double handling, the following automated material handling systems have been proposed:

[0044] Reference Figures 1 to 4 The automated material handling system includes an automated overhead crane 1, a support plate 2, a dual-load-in sensor 3, and a reflector 4. The dual-load-in sensor 3 is installed on the top of the automated overhead crane 1, and the reflector 4 is located at the bottom of the support plate 2. The dual-load-in sensor 3 is a photoelectric sensor.

[0045] When no wafer cassette 100 is placed on the carrier plate 2, the light emitted by the dual-entry sensor 3 can be received by the reflector plate 4 and reflected back to the dual-entry sensor 3, thereby confirming that there is no wafer cassette on the carrier plate 2.

[0046] When a wafer cassette 100 is placed on the carrier plate 2, the light emitted by the dual-entry sensor 3 is blocked and cannot be received and reflected by the reflector 4, thus confirming that there is a wafer cassette on the carrier plate 2.

[0047] The wafer housing is usually transparent, and the chips inside are black or colored. Therefore, the black or colored chips will block the light emitted from the dual-entry sensor from reaching the reflector.

[0048] However, as Figure 5 As shown, when there is no wafer 200 in the wafer cassette 100, the wafer cassette 100 placed on the carrier plate 2 is transparent. The light emitted by the double-entry sensor 3 will pass through the wafer cassette 100 and shine on the reflector plate 4, and be reflected back to the double-entry sensor 3, thereby confirming that there is no wafer cassette on the carrier plate 2, thus causing a misjudgment and leading to the subsequent double-entry problem.

[0049] This invention provides an automatic material handling device, such as... Figure 6 As shown, it includes a crane 10, a support plate 20, a photoelectric sensing mechanism 30, and a reflection mechanism 40.

[0050] The overhead crane 10 is movably mounted on the overhead crane track. A support plate 20 is located below the overhead crane 10 and has opposing first surfaces S1 and second surfaces S2; the first surface S1 is used to support materials. A photoelectric sensing mechanism 30 is mounted on the overhead crane 10. Figure 9 and Figure 12 As shown, the reflection mechanism 40 includes a triggering part 41, a reflector plate 42, and a transmission part 43. The reflector plate 42 and the transmission part 43 are located below the support plate 20. The triggering part 41 is connected to the reflector plate 42 through the transmission part 43. The triggering part 41 can move up and down relative to the support plate 20. When there is no material on the first surface S1, one end of the triggering part 41 protrudes from the first surface S1 of the support plate, and the reflector plate 42 is in the first position, such as... Figure 7 and Figure 12 As shown; when material is present on the first surface S1 of the bearing plate 20, one end of the trigger part 41 is pressed down by the material and moves downward, driving the reflector plate 42 to move to the second position via the transmission part 43, as shown. Figure 8 and Figure 13 As shown; when the reflector 42 is in the first position, the reflector 42 can receive light from the photoelectric sensing mechanism 30 and reflect the light back to the photoelectric sensing mechanism 30, and the photoelectric sensing mechanism 30 generates a first signal; when the reflector 42 is in the second position, the reflector 42 cannot receive light from the photoelectric sensing mechanism 30, and the photoelectric sensing mechanism 30 generates a second signal.

[0051] In this embodiment, the automatic material handling equipment is applied in the semiconductor manufacturing field to transfer wafer cassette 100. The material is wafer cassette 100. The first surface S1 of the support plate 20 is provided with a positioning post 110 for positioning the wafer cassette 100. When the trigger part 41 is not pressed down by the wafer cassette 100, that is, in the initial state, the height of the trigger part 41 protruding from the support plate 20 is greater than the height of the positioning post 110.

[0052] In this embodiment, the surface of the reflector 42 has a reflective material.

[0053] During application, since there is no wafer cell 100 pressing the trigger part 41 on the carrier plate 20, when the reflector plate 42 is in the first position, the photoelectric sensing mechanism 30 generates a first signal to confirm that there is no wafer cell 100 on the carrier plate 20.

[0054] When a wafer cell 100 is present on the carrier plate 20, the wafer cell 100 presses down on the trigger part 41, causing the reflector 42 to move to a second position. This position cannot receive light from the photoelectric sensing mechanism 30. The photoelectric sensing mechanism 30 generates a second signal to confirm that a wafer cell 100 is present on the carrier plate 20.

[0055] Therefore, the reflector 42 of the present invention can change its position based on whether the wafer cassette 100 is present, so that the photoelectric sensing mechanism 30 generates a corresponding sensing signal. Compared with the automatic material handling system in the related art where the reflector 42 is fixed, the automatic material handling equipment of the present invention can accurately sense whether the wafer cassette 100 is present, and will not produce false judgments even if there are no wafers in the wafer cassette 100. Furthermore, the present invention has a simple structure and is easy to implement.

[0056] In this embodiment, as Figures 10 to 13 As shown, the transmission part 43 includes a first engagement part 431 and a second engagement part 432. The first engagement part 431 is fixedly connected to the trigger part 41, and the second engagement part 432 is connected to the reflector plate 42. The first engagement part 431 and the second engagement part 432 engage, wherein the first engagement part 431 is a rack and pinion, and the second engagement part 432 is a gear. During the movement of the trigger part 41, the reflector plate 42 can move between a first position and a second position through the transmission of the first engagement part 431 and the second engagement part 432.

[0057] It should be understood that the form of the first meshing part 431 and the second meshing part 432 is not limited to this. For example, the first meshing part 431 is a gear and the second meshing part 432 is a rack.

[0058] In this embodiment, as Figures 10 to 13 As shown, one end of the first engaging part 431 is fixedly connected to the other end of the trigger part 41 and is coaxial with the trigger part 41. The reflection mechanism 40 also includes a stop part 46, which is fixed to one end of the first engaging part 431. When the reflector plate 42 is in the first position, the stop part 46 abuts against the second surface S2, as shown. Figure 12 As shown. Therefore, by providing the stop part 46, the position of the trigger part 41 can be limited by the stop part 46 when it is not pressed down by an external force.

[0059] In this embodiment, the reflection mechanism 40 further includes an elastic part (not shown), which is connected to the trigger part 41, such as... Figure 12 As shown, when the trigger part 41 is not pressed down by an external force, the reflector 42 is in the first position and the elastic part is in a free state; when the trigger part 41 is pressed down by an external force, the reflector 42 is in the second position and the elastic part deforms, as shown... Figure 13 As shown; after the external force is removed, the trigger part 41 rises through the elastic restoring force of the elastic part, causing the reflector 42 to return to the first position.

[0060] The elastic element is, for example, a spring, and the appropriate type can be selected according to its location.

[0061] For example, the elastic part is a compression spring, that is, it is stretched in the free state and can withstand inward pressure. When the trigger part 41 is pressed down by an external force, the elastic part is compressed and the reflector 42 is in the second position. After the external force is removed, the trigger part 41 rises by the elastic restoring force of the elastic part, so that the reflector 42 is in the first position.

[0062] Alternatively, the elastic part can be a tension spring, that is, it is compressed in its free state and can withstand outward pulling force. When the trigger part 41 is pressed down by an external force, the elastic part is stretched, and the reflector 42 is in the second position. After the external force is removed, the trigger part 41 rises through the elastic restoring force of the elastic part, so that the reflector 42 is in the first position.

[0063] Therefore, by providing an elastic part, the trigger part 41 can quickly rise and return to its initial position after the external force is removed, i.e., when there is no wafer cell 100. Correspondingly, the reflector 42 returns to the first position to avoid affecting the sensing of the photoelectric sensing mechanism 30.

[0064] When the reflector 42 is in the first position, it is parallel to the support plate 20. In this embodiment, the reflector 42 is horizontal in the first position. When the reflector 42 is in the second position, it is approximately perpendicular to the support plate 20. In this embodiment, the angle between the reflector 42 and the horizontal position is 80° to 100°. In this embodiment, when the reflector 42 is in the second position, it is vertical, that is, the angle between the reflector 42 and the horizontal position is 90°. In this embodiment, the reflector 42 varies between the horizontal and vertical positions.

[0065] It should be understood that the position of the reflector 42 is not limited to this and can be changed accordingly based on the position of the photoelectric sensing mechanism 30, the photoelectric signal sensing path, etc.

[0066] In this embodiment, as Figure 9 , 10 As shown, the reflecting mechanism 40 also includes a mounting base 44, a connecting rod 45, and a bearing (not shown). The bearing is mounted on the connecting rod 45. The reflecting plate 42 is rotatably connected to the mounting base 44 via the connecting rod 45. The mounting base 44 is disposed on the second surface S2 of the support plate 20. The second engaging part 432 is fixedly connected to the connecting rod 45. During rotation, the second engaging part 432 can drive the reflecting plate 42 to rotate between a first position and a second position. The number of mounting bases 44 can be a pair, symmetrically arranged on opposite sides of the reflecting plate 42. The transmission part 43 can be adjacent to one of the mounting bases 44.

[0067] It should be understood that the installation method of the reflector 42 is not limited to this, and any mechanical connection method that can connect the reflector 42 with the carrier plate and the transmission part 43 is applicable.

[0068] In addition, the number of reflective mechanisms 40 is one or more.

[0069] In this embodiment, there is one reflective mechanism 40, which can be located below the center of the support plate 20.

[0070] In other embodiments, there may be multiple reflective mechanisms 40, which are evenly distributed below the center of the support plate 20. Multiple reflective mechanisms 40 can be driven independently by corresponding transmission parts 43, or they can share a single transmission part 43.

[0071] In this embodiment, the automated material handling equipment may further include a control mechanism (not shown) that is capable of receiving signals from the photoelectric sensing mechanism 30.

[0072] Specifically, such as Figure 14 As shown, when the reflector can receive light from the photoelectric sensing mechanism, the photoelectric sensing mechanism generates a first signal. The first signal indicates that there is no material on the carrier plate, and the control mechanism can respond to the first signal to control the crane's gripping mechanism to lower the material at this station.

[0073] When the reflector does not receive light from the photoelectric sensing mechanism, the photoelectric sensing mechanism generates a second signal, indicating that there is material on the carrier plate. The control mechanism responds to this second signal by controlling the overhead crane to move to the next lowering station. Upon reaching the next lowering station, the above method is repeated to determine whether there is material at that station. This invention provides an automated material handling method, which utilizes the aforementioned automated material handling equipment, including:

[0074] The overhead crane moves to the top of the support plate of a workstation and controls the crane's movement based on the signal emitted by the photoelectric sensing mechanism.

[0075] When the photoelectric sensing mechanism generates the first signal, the crane's gripping mechanism lowers the material at this station.

[0076] When the photoelectric sensing mechanism generates a second signal, it controls the overhead crane to move to the next lowering station. Upon reaching the next lowering station, the above method is repeated to determine whether there is material at that station.

[0077] Therefore, the automated material handling device and method of the present invention can accurately determine whether materials, such as wafer cassettes, are present at each workstation, thereby ensuring accurate placement of wafer cassettes at each workstation. Even if there are no wafers in the wafer cassette, no misjudgment will occur. Furthermore, the present invention has a simple structure, is easy to implement, and does not affect placement efficiency.

[0078] In summary, the reflector of this invention can change its position based on the presence or absence of a wafer cassette, thereby enabling the photoelectric sensing mechanism to generate a corresponding sensing signal. Compared to automated material handling systems in related technologies where the reflector remains stationary, the automated material handling equipment of this invention can accurately sense the presence or absence of a wafer cassette, preventing false alarms even if no wafer is present. Furthermore, this invention has a simple structure and is easy to implement.

[0079] Although the invention has been described with reference to several exemplary embodiments, it should be understood that the terminology used is descriptive and exemplary, and not restrictive. Since the invention can be embodied in many forms without departing from the spirit or essence of the invention, it should be understood that the above embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope defined by the appended claims. Therefore, all variations and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. An automatic material handling device, characterized in that, include: The overhead crane is movably installed on the overhead crane track; A support plate, located below the overhead crane, has opposing first and second surfaces, the first surface being used to support materials; A photoelectric sensing mechanism is installed on the overhead crane; and A reflecting mechanism includes a triggering part, a reflector plate, a transmission part, and an elastic part. The reflector plate and the transmission part are located below the support plate. The triggering part is connected to the reflector plate through the transmission part and can move up and down relative to the support plate. The elastic part is connected to the triggering part. When there is no material on the first surface, one end of the triggering part protrudes from the first surface of the support plate, the reflector plate is in a first position, and the elastic part is in a free state. When there is material on the first surface of the support plate, one end of the triggering part is pressed down by the material and moves downward, driving the reflector plate to a second position through the transmission part, and the elastic part deforms. When the reflector plate is in the first position, it can receive light from the photoelectric sensing mechanism and reflect the light back to the photoelectric sensing mechanism, which generates a first signal. When the reflector plate is in the second position, it cannot receive light from the photoelectric sensing mechanism, which generates a second signal. After the external force is removed, the trigger part rises due to the elastic restoring force of the elastic part, causing the reflector to return to the first position; The transmission part includes a first engagement part and a second engagement part. The first engagement part is fixedly connected to the trigger part, and the second engagement part is connected to the reflector. The first engagement part and the second engagement part engage. During the movement of the trigger part, the reflector can move between the first position and the second position through the transmission of the first engagement part and the second engagement part.

2. The automatic material handling equipment according to claim 1, characterized in that, The first meshing part is a rack, and the second meshing part is a gear.

3. The automatic material handling equipment according to claim 2, characterized in that, The reflecting mechanism further includes a mounting base, a connecting rod, and a bearing. The bearing is assembled on the connecting rod. The reflecting plate is rotatably connected to the mounting base through the connecting rod. The mounting base is disposed on the second surface of the support plate. The second engaging part is fixedly connected to the connecting rod. During the rotation of the second engaging part, the reflecting plate can be driven to rotate between the first position and the second position.

4. The automatic material handling equipment according to claim 3, characterized in that, One end of the first engaging part is fixedly connected to the other end of the trigger part and is coaxial with the trigger part. The reflection mechanism also includes a stop part, which is fixed to one end of the first engaging part. When the reflector is in the first position, the stop part abuts against the second surface.

5. The automatic material handling equipment according to claim 3, characterized in that, The number of mounting bases is one pair, which are symmetrically arranged on opposite sides of the reflector, with the transmission part adjacent to one of the mounting bases.

6. The automatic material handling equipment according to claim 3, characterized in that, When the reflector is in the first position, the reflector and the support plate are parallel to each other; when the reflector is in the second position, the angle between the reflector and the support plate is 80° to 100°.

7. The automatic material handling equipment according to claim 6, characterized in that, When the reflector is in the first position, the reflector is in a horizontal position; when the reflector is in the second position, the reflector is perpendicular to the horizontal position.

8. The automatic material handling equipment according to claim 7, characterized in that, When the reflector is in the second position, the reflector is in a vertical position.

9. The automatic material handling equipment according to claim 1, characterized in that, The number of the reflective mechanisms is one or more.

10. The automatic material handling equipment according to claim 9, characterized in that, The number of the reflective mechanism is one, which is located below the center of the support plate.

11. The automatic material handling equipment according to claim 9, characterized in that, The number of the reflective mechanisms is multiple, and they are evenly distributed below the center of the support plate.

12. The automatic material handling equipment according to claim 1, characterized in that, The surface of the reflector has a reflective material.

13. The automatic material handling equipment according to claim 1, characterized in that, The automated material handling equipment also includes a control mechanism, which is capable of controlling the overhead crane's gripping mechanism to lower materials in response to the first signal, and is capable of controlling the overhead crane to move to the next lowering station in response to the second signal.

14. An automated material handling method, performed using the automated material handling equipment as described in any one of claims 1 to 13, characterized in that, include: The overhead crane moves to the top of the support plate of a workstation, and controls the crane's movement based on the signal emitted by the photoelectric sensing mechanism; When the photoelectric sensing mechanism generates a first signal, it controls the crane's gripping mechanism to lower the material to the workstation. When the photoelectric sensing mechanism generates a second signal, it controls the overhead crane to move to the next work station.

Images