Adjustable plate turnover machine

Abstract

The utility model relates to the technical field of conveying equipment, in particular to an adjustable plate turnover machine, which is characterized in that a turnover frame is provided with a fixed frame and a movable frame capable of moving towards or away from the fixed frame, and the fixed frame is provided with a left conveying part; the movable frame is provided with a right side conveying part used for being matched with the left side conveying part to convey the material plate. The tail end of the left side conveying part and the tail end of the right side conveying part are each provided with a material blocking mechanism used for blocking a material plate to an overturning position in the conveying process. The left side conveying part comprises a first conveying part used for conveying a material plate to be overturned and a second conveying part used for conveying the overturned material plate, and the second conveying part is arranged above the first conveying part. In the process of overturning the material plate, the material blocking mechanism can support the material plate, so that the material plate cannot be separated from the left side conveying part and the right side conveying part; and after force is applied to the movable frame, material plates of different sizes are conveyed, and the practicability of the plate turnover machine is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to conveying equipment technical field especially relates to an adjustable turnover plate machine. BACKGROUND

[0002] In industrial production, the turnover plate machine is a commonly used equipment, mainly used for turning over the plate material to facilitate subsequent processing or processing. However, the turnover plate machine in the prior art generally has the problem of instability when turning over the plate. This instability can cause the material to slide or deviate during the turning over process, not only affecting the turning over efficiency, but also possibly damaging the material and even threatening the safety of the operator.

[0003] The turnover plate machine in the prior art usually adopts a fixed conveying structure, which cannot adapt to different sizes of materials. When the size of the material changes, it is often necessary to adjust the structure of the entire turnover plate machine or replace the equipment, which not only increases the production cost, but also reduces the production flexibility. Therefore, the present application provides an adjustable turnover plate machine to solve the above technical problems. SUMMARY

[0004] The utility model aims at the deficiency of prior art provides an adjustable turnover plate machine to solve the technical problem that the existing turnover plate machine is unstable when turning over and cannot adapt to different sizes of material plates.

[0005] To achieve the above purpose, the technical scheme of the utility model is as follows:

[0006] An adjustable turnover plate machine comprises a housing and a support frame installed inside the housing, and further comprises a turnover frame installed on the support frame based on a transverse axis; a fixed frame and a movable frame that can move towards or away from the fixed frame are installed on the turnover frame, the fixed frame is provided with a left side conveying part, and the movable frame is provided with a right side conveying part for cooperating with the left side conveying part to convey the material plate.

[0007] The end of the left side conveying part and the end of the right side conveying part are both provided with a material blocking mechanism for blocking the material plate in the conveying process to the turnover position; the left side conveying part comprises a first conveying part for conveying the material plate to be turned over and a second conveying part for conveying the turned over material plate, and the second conveying part is arranged above the first conveying part.

[0008] Further, the support frame is provided with a fixing seat, the turnover frame is provided with a shaft axis transversely arranged and rotationally connected with the fixing seat; the support frame is provided with a first servo motor, the output shaft of the first servo motor is coaxially arranged with the shaft, and the output shaft is fixedly connected with the turnover frame.

[0009] Further, a plurality of guide rods parallel to the axis of the rotating shaft are arranged on the turnover frame, and the movable frame is slidingly arranged on the guide rods.

[0010] Further, a feeding port is formed on the side wall of the shell and is aligned with the initial end of the left and right conveying portions, and a discharging port is formed on the side wall of the shell and is aligned with the end of the left and right conveying portions.

[0011] Further, a plurality of lead screws parallel to the axis of the guide rods are rotatably arranged on the turnover frame, the lead screws are threadedly connected with the movable frame, first sprockets are arranged on the same side of the ends of the plurality of lead screws, a second servo motor is arranged on the turnover frame, a second sprocket is arranged on the output shaft of the second servo motor, and the chain is wound around the first sprockets and the second sprocket.

[0012] Further, the first conveying portion comprises third and fourth conveying wheels arranged at the same height and in the conveying direction of the material plate, the third and fourth conveying wheels are rotatably arranged on the fixed frame, and the second conveying belt is wound around the third and fourth conveying wheels; the second conveying portion comprises first and second conveying wheels arranged at the same height and in the conveying direction of the material plate, the first and second conveying wheels are rotatably arranged on the fixed frame, and the first conveying belt is wound around the first and second conveying wheels.

[0013] Further, the first conveying wheel is provided with a first connecting shaft arranged transversely, the third conveying wheel is provided with a second connecting shaft parallel to the first connecting shaft, the first and second connecting shafts are rotatably arranged on the fixed frame; a first driven wheel is arranged on the end of the first connecting shaft, a second driven wheel is arranged on the end of the second connecting shaft, a driving motor is arranged on the fixed frame, a driving wheel is arranged on the output shaft of the driving motor, and the first and second driven wheels are engaged with the driving wheel.

[0014] Further, the material blocking mechanism comprises a support rod arranged on the fixed frame and arranged transversely, the length direction of the support rod is perpendicular to the conveying direction of the material plate, a material blocking plate is slidingly arranged on the support rod, and a first cylinder for controlling the sliding of the material blocking plate on the support rod is arranged on the fixed frame.

[0015] Further, the clamping mechanism arranged on the fixed frame comprises a pair of second cylinders arranged on the upper and lower sides of the conveying track of the material plate, the extension rods of the second cylinders arranged on the upper and lower sides are oppositely arranged, the second cylinders are arranged on the fixed frame through mounting plates, a clamping plate for clamping and limiting the turnover material plate is arranged on the end of the extension rod of each second cylinder; an elastic member is arranged on the end surface of each clamping plate in contact with the material plate.

[0016] Further, the fixing frame is fixed with a limiting block deviating from the rotating axis of the turnover frame, and the supporting frame is provided with a first stop block and a second stop block symmetrically arranged based on the rotating axis of the turnover frame and used for limiting the rotation of the limiting block within a specified range.

[0017] The utility model discloses the beneficial effects of: when using, the left side conveying part and the right side conveying part are operated simultaneously, and the material plate to be turned over is conveyed to the first conveying part, in the process of conveying, the material blocking mechanism is operated, and after the material plate to be turned over is blocked to the specified turnover position on the first conveying part, the left side conveying part and the right side conveying part are stopped, and then the turnover frame is controlled to turn over 180 degrees on the supporting frame to clockwise turn over the material plate.

[0018] In addition, the material blocking mechanism can not only accurately turn over the material plate, but also hold the material plate during the turnover of the material plate, so that the material plate does not separate from the left side conveying part and the right side conveying part, improves the turnover efficiency, and is more stable when turning over the material plate.

[0019] After the movable frame is forced, the right side conveying part can be moved towards or away from the left side conveying part, so that the material plate of different sizes can be conveyed and turned over, and the practicability of the material turning machine is improved. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a three-dimensional structure schematic view of the utility model.

[0021] Figure 2 It is an internal structure schematic view of the utility model.

[0022] Figure 3 It is a part structure schematic view of the utility model.

[0023] Figure 4 It is a structure schematic view of the left side conveying part and the material blocking mechanism of the utility model.

[0024] Figure 5 It is another view structure schematic view of the left side conveying part and the material blocking mechanism of the utility model.

[0025] Figure 6 It is a structure schematic view of the clamping mechanism of the utility model.

[0026] The reference signs include:

[0027] 1, shell; 101, feed inlet; 102, discharge outlet; 2, support frame; 3, fixed seat; 4, rotating shaft; 5, turnover frame; 6, first servo motor; 7, fixed frame; 8, guide rod; 9, movable frame; 10, left side conveying part; 1001, first conveying wheel; 1002, second conveying wheel; 1003, first conveying belt; 1004, first connecting shaft; 1005, first driven wheel; 1006, third conveying wheel; 1007, fourth conveying wheel; 1008, second conveying belt; 1009, second connecting shaft; 1010, second driven wheel; 1011, drive motor; 1012, driving wheel; 11, right side conveying part; 12, screw rod; 13, first sprocket; 14, second servo motor; 15, second sprocket; 16, chain; 17, material blocking mechanism; 171, support rod; 172, material blocking plate; 173, first cylinder; 18, clamping mechanism; 181, mounting plate; 182, second cylinder; 183, clamping plate; 184, elastic member; 19, limiting block; 20, first stop block; 21, second stop block; 22, infrared sensor. DETAILED DESCRIPTION

[0028] The adjustable turnover machine is described in detail below with reference to the drawings.

[0029] As Figures 1-3 shown, the embodiment of the adjustable turnover machine includes a shell 1 and a support frame 2 installed inside the shell 1, and further includes a turnover frame 5 placed inside the shell 1 and a fixed seat 3 fixedly arranged on the support frame 2. The turnover frame 5 is provided with a rotating shaft 4 arranged transversely and rotationally connected with the fixed seat 3. By rotating the rotating shaft 4 on the fixed seat 3, the turnover frame 5 can rotate around the transverse axis inside the shell 1. In order to drive the turnover frame 5 to rotate by a specified angle, a first servo motor 6 is further installed on the support frame 2. The output shaft of the first servo motor 6 is coaxially arranged with the rotating shaft 4, and the output shaft is fixedly connected with the turnover frame 5. By operating the first servo motor 6, the turnover frame 5 can be driven to rotate by a specified angle (i.e. 180°).

[0030] The fixed frame 7 is provided with a plurality of guide rods 8 parallel to the axis of the rotating shaft 4, and the movable frame 9 is slidably arranged on the guide rods 8. When a force is applied to the movable frame 9, the movable frame 9 moves towards or away from the fixed frame 7. In addition, the fixed frame 7 is provided with a left conveying part 10, and the movable frame 9 is provided with a right conveying part 11 for cooperating with the left conveying part 10 to convey the material plate. The left conveying part 10 and the right conveying part 11 are used to convey the material plate before and after the material plate is flipped. An inlet 101 is formed on the side wall of the shell 1 and aligned with the initial end of the left conveying part 10 and the right conveying part 11, and an outlet 102 is aligned with the end of the left conveying part 10 and the right conveying part 11. The inlet 101 and the outlet 102 are connected to different conveying devices (not shown in the figure). The material plate is conveyed from the inlet 101 to the left conveying part 10 and the right conveying part 11 by the conveying device (not shown in the figure). Then, the first servo motor 6 is operated to drive the flipping frame 5 to rotate 180°, thereby driving the material plate to flip 180°. After the flipping is completed, the left conveying part 10 and the right conveying part 11 are operated to convey the flipped material plate to another conveying device (not shown in the figure). Finally, the first servo motor 6 drives the flipping frame 5 to rotate in the opposite direction to reset, thereby facilitating the flipping of the next material plate. In the process of conveying the material plate, the flipping of the material plate is completed under the cooperation of the above-mentioned mechanisms, thereby facilitating the subsequent processing of the material plate. In addition, when a force is applied to the movable frame 9, the right conveying part 11 moves towards or away from the left conveying part 10, thereby realizing the conveying of material plates of different sizes and the flipping of material plates of different sizes. The material plate can be a circuit board, a PCB board or the like.

[0031] A material blocking mechanism 17 is arranged at the end of the left conveying part 10 and the end of the right conveying part 11 to block the material plate in the flipping position during conveying. The left conveying part 10, the right conveying part 11 and the conveying device (not shown in the figure) connected to the inlet 101 are operated to convey the material plate to be flipped to the left conveying part 10 and the right conveying part 11. During the conveying process, the material blocking mechanism 17 is operated to block the material plate to be flipped to the specified flipping position on the left conveying part 10 and the right conveying part 11. Then, the left conveying part 10 and the right conveying part 11 are stopped, and the first servo motor 6 is operated to flip the material plate clockwise (the flipping direction is taken as the reference) for flipping processing. In addition, during the flipping of the material plate, the material blocking mechanism 17 can hold the material plate, so that the material plate does not fall off the left conveying part 10 and the right conveying part 11, thereby improving the flipping efficiency. Figure 2

[0032] ​In order to make the material plate more stable in the process of turning over, the clamping mechanism 18 for clamping and limiting the material plate in the process of turning over is arranged on the fixed frame 7 and the movable frame 9. When the material plate in the conveying process is blocked to the turning over position by the blocking mechanism 17, the clamping mechanism 18 is operated to clamp the material plate, so that the material plate does not move or deviate on the left conveying part 10 and the right conveying part 11 in the process of turning over, thereby improving the efficiency of turning over.

[0033] Further, the turning frame 5 is rotationally provided with a plurality of lead screws 12 parallel to the axis of the guide rod 8, the lead screws 12 are threadedly connected with the movable frame 9, a first sprocket 13 is arranged on each end of the same side of the plurality of lead screws 12, the turning frame 5 is provided with a second servo motor 14, and a second sprocket 15 is arranged on the output shaft of the second servo motor 14, and the chain 16 is wound around the first sprocket 13 and the second sprocket 15. The second servo motor 14 is operated to drive the second sprocket 15 to rotate, and under the transmission of the chain 16 and the first sprocket 13, the plurality of lead screws 12 can be synchronously driven to rotate.

[0034] As shown in Figures 4-5 , the left conveying part 10 and the right conveying part 11 have the same structure and consistent operation mode, wherein the left conveying part 10 comprises a first conveying part for conveying the material plate to be turned over and a second conveying part for conveying the turned over material plate, and the second conveying part is arranged directly above the first conveying part; the material plate to be turned over is conveyed by the first conveying part, and after the material plate is turned over by 180°, the material plate is arranged on the second conveying part, and the turned over material plate can be conveyed out of the material plate turning machine by controlling the operation of the second conveying part.

[0035] Specifically, the first conveying part comprises the third conveying wheel 1006 and the fourth conveying wheel 1007 arranged at the same height and along the conveying direction of the material plate, the third conveying wheel 1006 and the fourth conveying wheel 1007 are rotationally arranged on the fixed frame 7, and the second conveying belt 1008 is wound around the third conveying wheel 1006 and the fourth conveying wheel 1007. Figure 5 When the third conveying wheel 1006 or the fourth conveying wheel 1007 is driven to rotate clockwise (the rotation direction is taken as the reference), the second conveying belt 1008 can be driven to move to convey the material plate to be turned over.

[0036] The second conveying part comprises the first conveying wheel 1001 and the second conveying wheel 1002 arranged at the same height and along the conveying direction of the material plate, the first conveying wheel 1001 and the second conveying wheel 1002 are rotationally arranged on the fixed frame 7, the first conveying belt 1003 is arranged around the first conveying wheel 1001 and the second conveying wheel 1002; when the third conveying wheel 1006 or the fourth conveying wheel 1007 is driven to rotate clockwise, the first conveying wheel 1001 or the second conveying wheel 1002 is also driven to rotate clockwise, so that the conveying track of the first conveying belt 1003 is opposite to the conveying track of the second conveying belt 1008, when the turned-over material plate is placed on the first conveying belt 1003, the conveying direction of the material plate will not change, and the material plate is still conveyed towards the discharge port 102.

[0037] In order to control the first conveying belt 1003 and the second conveying belt 1008 to move simultaneously, the first connecting shaft 1004 is arranged transversely on the first conveying wheel 1001, the second connecting shaft 1009 parallel to the first connecting shaft 1004 is arranged on the third conveying wheel 1006, and the first connecting shaft 1004 and the second connecting shaft 1009 are rotationally arranged on the fixed frame 7; wherein the first driven wheel 1005 is arranged on the end of the first connecting shaft 1004, the second driven wheel 1010 is arranged on the end of the second connecting shaft 1009, the fixed frame 7 is provided with the driving motor 1011, the output shaft of the driving motor 1011 is provided with the driving wheel 1012, and the first driven wheel 1005 and the second driven wheel 1010 are engaged with the driving wheel 1012. When the driving motor 1011 is operated, the driving wheel 1012 is driven to rotate counterclockwise (the rotating direction is taken as the reference), thereby driving the first driven wheel 1005 and the second driven wheel 1010 to rotate clockwise simultaneously, so as to drive the first conveying wheel 1001 and the third conveying wheel 1006 to rotate clockwise, so that the conveying track of the first conveying belt 1003 is opposite to the conveying track of the second conveying belt 1008, and the conveying direction of the material plate to be turned over is consistent with the conveying direction of the turned-over material plate. Figure 5

[0038] ​Further, the material blocking mechanism 17 comprises a support rod 171 arranged on the fixed frame 7 and transversely arranged, the length direction of the support rod 171 is perpendicular to the conveying direction of the material plate, a material blocking plate 172 is slidingly arranged on the support rod 171, and a first air cylinder 173 for controlling the sliding of the material blocking plate 172 on the support rod 171 is arranged on the fixed frame 7. The end of the telescopic rod of the first air cylinder 173 is fixedly connected with the material blocking plate 172, and the initial state of the telescopic rod of the first air cylinder 173 is the extended state. During the conveying of the material plate by the left conveying part 10 and the right conveying part 11, the first air cylinder 173 is operated, the telescopic rod of the first air cylinder 173 is retracted, thereby driving the material blocking plate 172 to slide on the support rod 171 to slide to the conveying track of the material plate, thereby blocking the material plate to the overturning position, and the subsequent overturning treatment can be performed; and during the overturning, the material blocking plate 172 can also support the material plate to prevent the material plate from being separated from the left conveying part 10 and the right conveying part 11.

[0039] As shown in Figure 6 The clamping mechanism 18 arranged on the fixed frame 7 and the clamping mechanism 18 arranged on the movable frame 9 have the same structure and consistent operation mode; wherein the clamping mechanism 18 arranged on the fixed frame 7 comprises a pair of second air cylinders 182 arranged on the upper side and the lower side of the conveying track of the material plate respectively, and the telescopic rods of the second air cylinders 182 arranged on the upper side and the lower side are oppositely arranged, the second air cylinders 182 are arranged on the fixed frame 7 through mounting plates 181, and the end of the telescopic rod of each second air cylinder 182 is provided with a clamping plate 183 for clamping and limiting the overturned material plate; the second air cylinders 182 arranged on the upper side and the lower side are operated at the same time, thereby controlling the clamping plates 183 to move towards each other, clamping and limiting the overturned material plate, and the material plate will not move or deviate on the left conveying part 10 and the right conveying part 11 during the overturning of the material plate, thereby improving the overturning efficiency. The end face of each clamping plate 183 in contact with the material plate is provided with an elastic member 184, the elastic member 184 is a silica gel member, which prevents damage to the material plate during clamping.

[0040] In addition, the fixing frame 7 is fixed with a limiting block 19 deviating from the rotation axis of the turnover frame 5, and the limiting block 19 rotates 180° around the rotation axis of the turnover frame 5 after the turnover frame 5 is controlled to turn over 180°; the support frame 2 is provided with a first stop block 20 and a second stop block 21 arranged symmetrically based on the rotation axis of the turnover frame 5 and used for limiting the rotation of the limiting block 19 within a specified range. When the material plate to be turned over is conveyed, the limiting block 19 is in contact with the first stop block 20, and after the turnover frame 5 is controlled to turn over 180°, the limiting block 19 is in contact with the second stop block 21, so that the turnover frame 5 can only turn over 180° in the positive and negative directions under the cooperation of the limiting block 19, the first stop block 20 and the second stop block 21, thereby improving the economic system of turning over the material plate. An infrared sensor 22 for detecting the limiting block 19 is arranged on the side of the first stop block 20 and the side of the second stop block 21; when the infrared sensor 22 detects that the limiting block 19 is in contact with the first stop block 20, the material plate to be turned over can be conveyed to the left conveying part 10 and the right conveying part 11, and after the turnover frame 5 drives the material plate to turn over 180°, the infrared sensor 22 detects that the limiting block 19 is in contact with the second stop block 21, and then outputs a detection signal to control the left conveying part 10 and the right conveying part 11 to run and convey the turned-over material plate out of the material plate turning machine.

[0041] In summary, the utility model has the above-mentioned excellent characteristics, which can improve the performance of the previous technology and have practicality, and become a product with practical value.

[0042] The above is only the preferred embodiment of the utility model, and for those skilled in the art, according to the idea of the utility model, the specific implementation mode and application range can be changed, and the content of the specification should not be understood as the limitation of the utility model.

Claims

1. An adjustable flap machine characterized by: The utility model relates to a material plate turnover device, including shell (1) and the support frame (2) of installation in the inside of shell (1), still including the turnover frame (5) of based on transverse axis rotation arrangement on support frame (2), the fixed frame (7) of installation on turnover frame (5) and the movable frame (9) of the direction of approaching or far from fixed frame (7) can be active, fixed frame (7) installs left side conveying part (10), and the right side conveying part (11) of movable frame (9) is installed to be used for with left side conveying part (10) cooperation to convey material plate with right side conveying part (11); The end of left side conveying part (10) and the end of right side conveying part (11) are all equipped with the material mechanism (17) for stopping material plate in conveying process to turnover position, and left side conveying part (10) includes first conveying part for conveying material plate to be turned over and second conveying part for conveying material plate after turning over, and second conveying part is placed above first conveying part.

2. A tilting plate machine according to claim 1, characterized in that: Support frame (2) is equipped with fixed seat (3), and turnover frame (5) is equipped with the rotation axis (4) of axis transverse arrangement and rotation connection with fixed seat (3), and support frame (2) is equipped with first servo motor (6), and the output shaft of first servo motor (6) is coaxial with rotation axis (4), and output shaft is fixedly connected with turnover frame (5).

3. A tilting plate machine according to claim 1, characterized in that: Turnover frame (5) is equipped with a plurality of guide rods (8) of axis parallel with the axis of rotation axis (4), and movable frame (9) is slidably arranged on guide rod (8).

4. The adjustable flap machine of claim 1, wherein: The sidewall of shell (1) is formed with inlet (101) aligning the initial end of left side conveying part (10) and right side conveying part (11), and outlet (102) aligning the end of left side conveying part (10) and right side conveying part (11).

5. An adjustable flap machine according to claim 3, wherein: Turnover frame (5) is rotatably equipped with a plurality of lead screws (12) of axis parallel with the axis of guide rod (8), lead screw (12) is threadedly connected with movable frame (9), and the same side of a plurality of lead screws (12) is equipped with first sprocket (13) on each end, and turnover frame (5) is equipped with second servo motor (14), and the output shaft of second servo motor (14) is equipped with second sprocket (15), and first sprocket (13) and second sprocket (15) are wound with chain (16).

6. The adjustable flap machine of claim 1, wherein: First conveying part includes third conveying wheel (1006) and fourth conveying wheel (1007) at the same height and arranged along the material plate conveying direction, and third conveying wheel (1006) and fourth conveying wheel (1007) are rotatably arranged on fixed frame (7), and third conveying wheel (1006) and fourth conveying wheel (1007) are wound with second conveying belt (1008); second conveying part includes first conveying wheel (1001) and second conveying wheel (1002) at the same height and arranged along the material plate conveying direction, and first conveying wheel (1001) and second conveying wheel (1002) are rotatably arranged on fixed frame (7), and first conveying wheel (1001) and second conveying wheel (1002) are wound with first conveying belt (1003).

7. An adjustable flap machine according to claim 6, wherein: The first conveying wheel (1001) is provided with a first connecting shaft (1004) arranged transversely, the third conveying wheel (1006) is provided with a second connecting shaft (1009) parallel to the first connecting shaft (1004), and the first connecting shaft (1004) and the second connecting shaft (1009) are both rotationally arranged on the fixed frame (7); the end of the first connecting shaft (1004) is provided with a first driven wheel (1005), the end of the second connecting shaft (1009) is provided with a second driven wheel (1010), the fixed frame (7) is provided with a driving motor (1011), and the output shaft of the driving motor (1011) is provided with a driving wheel (1012); the first driven wheel (1005) and the second driven wheel (1010) are both engaged with the driving wheel (1012).

8. The adjustable flap machine of claim 1, wherein: The material blocking mechanism (17) comprises a support rod (171) arranged transversely on the fixed frame (7), the length direction of the support rod (171) is perpendicular to the conveying direction of the material plate, the support rod (171) is provided with a material blocking plate (172) slidingly, and the fixed frame (7) is provided with a first cylinder (173) for controlling the sliding of the material blocking plate (172) on the support rod (171).

9. An adjustable flap machine according to claim 8, characterized in that: The clamping mechanism (18) arranged on the fixed frame (7) comprises a pair of second cylinders (182) arranged on the upper and lower sides of the conveying track of the material plate, and the extension rods of the second cylinders (182) arranged on the upper and lower sides are oppositely arranged; the second cylinders (182) are arranged on the fixed frame (7) through mounting plates (181), and the extension rods of the second cylinders (182) are provided with clamping plates (183) for clamping and limiting the material plate after being turned over; the end faces of the clamping plates (183) in contact with the material plate are provided with elastic members (184).

10. The adjustable flap machine of claim 1, wherein: The fixed frame (7) is fixedly provided with a limiting block (19) deviating from the rotation axis of the turning frame (5), and the support frame (2) is provided with a first blocking block (20) and a second blocking block (21) arranged symmetrically based on the rotation axis of the turning frame (5) and used for limiting the rotation of the limiting block (19) within a specified range.

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