A double-hook intelligent gantry crane

Abstract

The present invention belongs to the technical field of gantry cranes, and specifically relates to a double-hook intelligent gantry crane, which includes a base plate, a support column and a crossbeam, a fixed frame is installed at the bottom of the crossbeam, a lifting component is slidably installed in the fixed frame, and an adjustment component is installed on the fixed frame, the lifting component includes a roller, and the adjustment component includes an intermittent gear and a fixed rack, the intermittent gear is coaxially installed with the roller, the fixed rack is installed in the fixed frame, and the intermittent gear is meshed with the fixed rack. In the process of the present invention lifting the goods by the hook, the rotation of the roller drives the winding of the lifting rope, and the roller drives the intermittent gear to rotate coaxially. At this time, the intermittent gear drives the relative movement of the roller by meshing with the fixed rack, so that the lifting rope tilts outward, and the lifting rope is in an inverted eight-shaped shape. Compared with the method of using vertical lifting ropes to lift goods in the prior art, the present invention can provide stronger stability and reduce the shaking frequency caused by wind.

Description

Technical Field

[0001] The invention belongs to the technical field of gantry cranes, and specifically relates to a double-hook intelligent gantry crane. Background Art

[0002] Gantry crane is a variation of bridge crane, also called gantry crane, which is mainly used for loading and unloading operations in outdoor cargo yards, material yards and bulk cargo. Gantry crane has the characteristics of high site utilization, large operating range, wide adaptability and strong versatility. It is widely used in port cargo yards or factories. At present, due to the advancement of science and technology, most gantry cranes have been equipped with intelligent electronic systems to facilitate crane control and monitoring.

[0003] The two sets of hooks of the double-hook intelligent gantry crane are installed in fixed positions. When lifting heavy objects of different lengths, the distance between the two sets of hooks can be adjusted according to the needs, making it inconvenient for the crane to lift heavy objects of different lengths, thereby greatly reducing the adjustability and applicability of the device. After searching, it was found that the Chinese patent with publication number CN115465790A mainly uses a sliding plate, a push-pull rod, a connecting block and a second electric pneumatic cylinder. When in use, the second electric pneumatic cylinder pushes or pulls the connecting block to move, so that the two sets of push-pull rods push or pull the sliding plate to move, and the distance between the two sets of hooks can be adjusted. However, the double hooks of the above scheme use a vertical lifting rope to lift the goods. Due to the characteristics of the gantry crane, when it moves the hoisted goods, the goods are prone to shaking under the action of inertia or wind, which is prone to danger. Summary of the invention

[0004] The purpose of the present invention is to provide a double-hook intelligent gantry crane to solve the technical problems in the prior art in view of the shortcomings of the prior art.

[0005] The object of the present invention can be achieved through the following technical scheme: a double-hook intelligent gantry crane, which includes a base plate, a support column and a crossbeam, a fixed frame is installed at the bottom of the crossbeam, a lifting component is slidably installed in the fixed frame, and an adjusting component is installed on the fixed frame, the lifting component includes a roller, and the adjusting component includes an intermittent gear and a fixed rack, the intermittent gear is coaxially installed with the roller, the fixed rack is installed in the fixed frame, and the intermittent gear is meshed with the fixed rack.

[0006] As a further optimization or improvement of this solution, a pitch adjusting assembly is installed on the fixed frame, the pitch adjusting assembly includes a motor and a forward and reverse screw rod, the forward and reverse screw rod is installed on the output shaft of the motor, and a transmission block is installed on the drum, and the transmission block cooperates with the forward and reverse screw rod for transmission.

[0007] As a further optimization or improvement of this solution, the lifting assembly is connected to the stop assembly through a connecting assembly, and the connecting assembly includes connecting rod 1 and connecting rod 2. Connecting rod 1 connects the stop assembly and the fixed frame, and connecting rod 2 connects the roller and the stop assembly.

[0008] As a further optimization or improvement of this solution, the stop assembly includes a stop box and a rope clamping box, a slide groove is provided at the bottom of the fixed frame, one end of connecting rod one is connected to the stop box, and the other end of connecting rod one is slidably matched with the slide groove, an annular groove is provided on the drum, one end of connecting rod two is connected to the rope clamping box, and the other end of connecting rod two is slidably matched with the annular groove.

[0009] As a further optimization or improvement of this solution, the stop assembly also includes an ejection plate, which is connected to the stop box through a stop spring, a moving block is slidably installed in the stop box, a moving roller is installed at one end of the moving block away from the stop box, the moving roller is slidably installed in the rope clamping box, and a fixed roller is fixedly installed inside the rope clamping box.

[0010] As a further optimization or improvement of this solution, a rack groove, a push groove and an arc groove are respectively provided on the stop box, a push rod is installed on the moving block, a rack body is installed on the ejection plate, and the push rod and the rack body are respectively located in the push groove and the rack groove and slide.

[0011] As a further optimization or improvement of this solution, the arc groove is connected to the gear sleeve through a reset spring, the movable tooth is installed on the gear sleeve, the push rod presses the gear sleeve, and the intermittent gear is connected to the movable tooth through a belt.

[0012] As a further optimization or improvement of the present scheme, the lifting assembly also includes a lifting rope and a lifting hook. When the hook spacing is adjusted, the lifting rope is in a vertical state. When the lifting hook lifts the goods and the drum rotates and reels, the drum drives the intermittent gear to rotate synchronously. The intermittent gear drives the drum to move relative to the fixed rack by meshing with the fixed rack, so that the lifting rope pulls the goods outward, and the lifting rope is tilted at this time.

[0013] As a further optimization or improvement of this solution, the crossbeam includes a transmission groove and a transmission box, the fixed frame is installed at the bottom of the transmission box, a transmission groove is opened on the side wall of the crossbeam, and the transmission box slides along the transmission groove.

[0014] Beneficial effects of the present invention:

[0015] (1) In the process of lifting the cargo by means of the hook, the drum rotates to drive the lifting rope to be reeled in, and the drum drives the intermittent gear to rotate coaxially. At this time, the intermittent gear drives the drum to move relative to the fixed rack by meshing with the fixed rack, so that the lifting rope tilts outward. At this time, the lifting rope is in an inverted figure eight shape. Compared with the method of lifting cargo by means of vertical lifting ropes in the prior art, the present invention can provide stronger stability and reduce the shaking frequency caused by wind.

[0016] (2) When the cargo shakes to the right during the lifting process, the left lifting rope is subjected to the downward pulling force and swings to the right, while the right lifting rope is subjected to the reduced pulling force of the cargo and has a tendency to move upward, and the right lifting rope swings to the right, see the figure. When the left lifting rope swings to the right, the lifting rope is separated from the pressure on the moving roller, and the limit of the push rod on the gear sleeve is released. At this time, under the action of the reset spring, the moving tooth is separated from the rack body. At this time, the compressed retaining spring rebounds quickly and drives the moving block and the moving roller to press the lifting rope through the ejection plate, so that the moving roller presses the lifting rope against the fixed roller. At this time, the lifting rope is bent by the pressure of the moving roller, and the moving roller provides an upward pulling force for the lifting rope. At this time, the upward pulling force of the lifting rope offsets the downward pulling force, thereby avoiding the tendency of cargo shaking and improving the stability and safety of cargo transportation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described below in conjunction with the accompanying drawings.

[0018] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0019] Figure 2 It is a schematic diagram of the connection structure between the transmission box and the fixed frame.

[0020] Figure 3 This is a schematic diagram of the distance adjustment component structure.

[0021] Figure 4 Schematic diagram of the internal structure of the fixed frame.

[0022] Figure 5 Schematic diagram of the adjustment component structure.

[0023] Figure 6 Schematic diagram of the connection component structure.

[0024] Figure 7 A schematic diagram of the stop assembly structure is shown in FIG.

[0025] Figure 8 This is the transmission coordination diagram of the moving gear and the push rod.

[0026] Fig. 9 This is an exploded view of the stop component structure.

[0027] Fig.10 This is a schematic diagram of the working status of the lifting component.

[0028] Fig.11 for Fig.10 Schematic diagram of the structure of part A.

[0029] Fig.12 This is the force analysis diagram of the suspension rope.

[0030] Fig.13 for Fig.12 Schematic diagram of the structure of part B.

[0031] The following are marked in the figure: 1. base plate; 2. support column; 3. crossbeam; 31. transmission groove; 32. transmission box; 4. fixed frame; 5. lifting assembly; 51. roller; 52. lifting rope; 53. hook; 6. distance adjustment assembly; 61. motor; 62. positive and negative screw rod; 63. transmission block; 7. adjustment assembly; 71. intermittent gear; 72. fixed rack; 8. stop assembly; 81. stop box; 82. stop spring; 83. ejection plate; 84. moving block; 85. moving roller; 86. rope clamping box; 87. fixed roller; 88. push rod; 89. rack body; 810. rack groove; 811. push groove; 813. arc groove; 814. reset spring; 815. gear sleeve; 816. moving tooth; 9. connecting assembly; 91. slide groove; 92. connecting rod one; 93. connecting rod two; 94. ring groove. DETAILED DESCRIPTION

[0032] 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.

[0033] See also Figure 1-Figure 5 A double-hook intelligent gantry crane includes a base plate 1, a support column 2 and a crossbeam 3, a fixed frame 4 is installed at the bottom of the crossbeam 3, a lifting component 5 is slidably installed in the fixed frame 4, and an adjusting component 7 is installed on the fixed frame 4. The lifting component 5 includes a roller 51, and the adjusting component 7 includes an intermittent gear 71 and a fixed rack 72. The intermittent gear 71 is coaxially installed with the roller 51, and the fixed rack 72 is installed in the fixed frame 4, and the intermittent gear 71 is meshed with the fixed rack 72.

[0034] Specifically, the cross beam 3 includes a transmission groove 31 and a transmission box 32 . The fixing frame 4 is installed at the bottom of the transmission box 32 . The transmission groove 31 is provided on the side wall of the cross beam 3 , and the transmission box 32 slides along the transmission groove 31 .

[0035] It should be noted that the substrate 1 is mounted on a guide rail, and a controller on the substrate 1 controls the substrate 1 to move along the guide rail.

[0036] The use of the present invention is as follows:

[0037] In the first step, the control substrate 1 moves along the guide rail to make the lifting assembly 5 close to the cargo, and then the transmission box 32 is started to move the transmission box 32 laterally along the transmission slot 31 on the crossbeam 3 to move the lifting assembly 5 to the top of the cargo;

[0038] The second step is to start the motor 61, so that the motor 61 drives the positive and negative threaded rods 62 to rotate, and the distance between the rollers 51 is adjusted by rotating the positive and negative threaded rods 62. At this time, the hanging rope 52 is in a vertical state, ensuring that the hook 53 can easily hook the goods;

[0039] The third step is to hook the goods by the hook 53, and then drive the roller 51 to reel in the lifting rope 52. At this time, the goods are continuously lifted, and at the same time, the roller 51 drives the intermittent gear 71 to rotate coaxially. At this time, the intermittent gear 71 drives the roller 51 to move relatively by meshing with the fixed rack 72. Fig.10 , at this time, the suspension rope 52 tilts outward;

[0040] Step 4: As the suspension rope 52 tilts, the suspension rope 52 squeezes the moving roller 85. Fig.11 At this time, the moving roller 85 moves toward the inside of the stop box 81, see Figure 8 As the moving roller 85 moves, the push rod 88 on the moving roller 85 presses the gear sleeve 815 and drives the gear sleeve 815 and the moving tooth 816 to move downward along the arc groove 813, so that the moving tooth 816 is meshed with the rack body 89. At this time, as the drum 51 is wound, the drum 51 drives the moving tooth 816 to rotate through the belt, so that the moving tooth 816 is meshed with the rack body 89 and drives the ejection plate 83 to press the stop spring 82;

[0041] Step 5: When the cargo shakes during lifting, Figure 1 As shown in the support column 2, the cargo sways to the right, and the left suspension rope 52 is pulled downward and swings to the right. The right suspension rope 52 is pulled less by the cargo and has a tendency to move upward, and the right suspension rope 52 swings to the right. Fig.13 When the left hanging rope 52 swings to the right, the hanging rope 52 is separated from the pressure on the moving roller 85, and the push rod 88 releases the limit of the gear sleeve 815. At this time, under the action of the reset spring 814, the moving tooth 816 is separated from the rack body 89. At this time, the compressed stop spring 82 rebounds quickly and drives the moving block 84 and the moving roller 85 to press the hanging rope 52 through the ejection plate 83, so that the moving roller 85 presses the hanging rope 52 against the fixed roller 87. At this time, the hanging rope 52 is bent by the pressure of the moving roller 85, and the moving roller 85 provides an upward pulling force for the hanging rope 52. At this time, the upward pulling force of the hanging rope 52 offsets the downward pulling force, thereby avoiding the tendency of the goods to shake.

[0042] See also Figure 3-Figure 4 The fixed frame 4 is provided with a pitch-adjusting assembly 6, which includes a motor 61 and a positive and negative screw rod 62. The positive and negative screw rod 62 is provided on the output shaft of the motor 61, and a transmission block 63 is provided on the roller 51. The transmission block 63 cooperates with the positive and negative screw rod 62 in transmission.

[0043] It should be noted that the distance-adjusting assembly 6 can drive the lifting assembly 5 to move relative to each other, thereby changing the distance between the hooks 53 so that it can adapt to the transportation of goods of different sizes.

[0044] See also Figure 5 and Figure 6 The lifting assembly 5 is connected to the stop assembly 8 through a connecting assembly 9. The connecting assembly 9 includes a connecting rod 1 92 and a connecting rod 2 93. The connecting rod 1 92 connects the stop assembly 8 and the fixed frame 4, and the connecting rod 2 93 connects the roller 51 and the stop assembly 8.

[0045] Specifically, the stop assembly 8 includes a stop box 81 and a rope clamping box 86, a slide groove 91 is provided at the bottom of the fixed frame 4, one end of a connecting rod 92 is connected to the stop box 81, and the other end of the connecting rod 92 is slidably matched with the slide groove 91, an annular groove 94 is provided on the drum 51, one end of a connecting rod 93 is connected to the rope clamping box 86, and the other end of the connecting rod 93 is slidably matched with the annular groove 94.

[0046] It should be noted that the connecting rod 1 92 connects the stop box 81 and the fixed frame 4 , and the connecting rod 2 93 connects the rope clamping box 86 and the drum 51 . When the drum 51 moves relatively along the fixed frame 4 , the stop assembly 8 moves synchronously with the drum 51 .

[0047] See also Figure 5-Figure 9 The stop assembly 8 also includes an ejection plate 83, which is connected to the stop box 81 through a stop spring 82. A moving block 84 is slidably installed in the stop box 81. A moving roller 85 is installed at one end of the moving block 84 away from the stop box 81. The moving roller 85 is slidably installed in a rope clamping box 86. A fixed roller 87 is fixedly installed inside the rope clamping box 86.

[0048] Specifically, the stop box 81 is respectively provided with a rack groove 810, a push groove 811 and an arc groove 813, the moving block 84 is provided with a push rod 88, the ejection plate 83 is provided with a rack body 89, and the push rod 88 and the rack body 89 are respectively located in the push groove 811 and the rack groove 810 and slide.

[0049] Specifically, the arc groove 813 is connected to the gear sleeve 815 through a return spring 814, the gear sleeve 815 is equipped with a moving tooth 816, the push rod 88 presses the gear sleeve 815, and the intermittent gear 71 is connected to the moving tooth 816 through a belt.

[0050] It should be noted that, in the process of the hook 53 lifting the cargo, the cargo is prone to sway due to the inertia of the cargo or the wind. In order to suppress the swaying of the cargo and improve the safety of the crane, the present invention installs a stopper assembly 8 at the bottom of the drum 51.

[0051] When the cargo is lifted by the hook 53, the rope 52 gradually tilts outwards under the action of the adjustment assembly 7, and the rope 52 squeezes the moving roller 85. Fig.11 At this time, the moving roller 85 moves toward the inside of the stop box 81, see Figure 8 As the moving roller 85 moves, the push rod 88 on the moving roller 85 presses the gear sleeve 815 and drives the gear sleeve 815 and the moving tooth 816 to move downward along the arc groove 813, so that the moving tooth 816 is engaged with the rack body 89. At this time, as the drum 51 is wound, the drum 51 drives the moving tooth 816 to rotate through the belt, so that the moving tooth 816 is engaged with the rack body 89 and drives the ejection plate 83 to press the stop spring 82; when the goods shake during the lifting process, such as Figure 1 As shown in the support column 2, the cargo sways to the right, and the left suspension rope 52 is pulled downward and swings to the right. The right suspension rope 52 is pulled less by the cargo and has a tendency to move upward, and the right suspension rope 52 swings to the right. Fig.13 When the left hanging rope 52 swings to the right, the hanging rope 52 is separated from the pressure on the moving roller 85, and the push rod 88 releases the limit of the gear sleeve 815. At this time, under the action of the reset spring 814, the moving tooth 816 is separated from the rack body 89. At this time, the compressed stop spring 82 rebounds quickly and drives the moving block 84 and the moving roller 85 to press the hanging rope 52 through the ejection plate 83, so that the moving roller 85 presses the hanging rope 52 against the fixed roller 87. At this time, the hanging rope 52 is bent by the pressure of the moving roller 85, and the moving roller 85 provides an upward pulling force for the hanging rope 52. At this time, the upward pulling force of the hanging rope 52 offsets the downward pulling force, thereby avoiding the tendency of the goods to shake.

[0052] When the goods are shaken to the left, the adjustment principle of the stop assembly 8 is the same as above.

[0053] See also Fig.10 The lifting assembly 5 also includes a lifting rope 52 and a hook 53. When the distance between the hooks 53 is adjusted, the lifting rope 52 is in a vertical state. When the hook 53 lifts the goods, the drum 51 rotates and reels, and the drum 51 drives the intermittent gear 71 to rotate synchronously. The intermittent gear 71 drives the drum 51 to move relative to the fixed rack 72 by meshing with the fixed rack 72, so that the lifting rope 52 pulls the goods outward, and the lifting rope 52 is tilted at this time.

[0054] The implementation principle of the present invention is:

[0055] When in use, the motor 61 drives the forward and reverse screw rods 62 to rotate, and the forward and reverse screw rods 62 rotate to adjust the distance between the rollers 51. At this time, the lifting rope 52 is in a vertical state, ensuring that the hook 53 is convenient for hooking the goods. Then the goods are hooked by the hook 53, and then the roller 51 is driven to reel in the lifting rope 52. At this time, the goods are continuously lifted, and at the same time, the roller 51 drives the intermittent gear 71 to rotate coaxially. At this time, the intermittent gear 71 drives the roller 51 to move relatively by meshing with the fixed rack 72. Fig.10 , at this time, the suspension rope 52 tilts outwards.

[0056] As the suspension rope 52 tilts, the suspension rope 52 squeezes the moving roller 85, see Fig.11 At this time, the moving roller 85 moves toward the inside of the stop box 81, see Figure 8 As the moving roller 85 moves, the push rod 88 on the moving roller 85 presses the gear sleeve 815 and drives the gear sleeve 815 and the moving tooth 816 to move downward along the arc groove 813, so that the moving tooth 816 engages with the rack body 89. At this time, as the roller 51 is wound, the roller 51 drives the moving tooth 816 to rotate through the belt, so that the moving tooth 816 engages with the rack body 89 and drives the ejection plate 83 to press the stop spring 82.

[0057] When the cargo shakes during lifting, Figure 1 As shown in the support column 2, the cargo sways to the right, and the left suspension rope 52 is pulled downward and swings to the right. The right suspension rope 52 is pulled less by the cargo and has a tendency to move upward, and the right suspension rope 52 swings to the right. Fig.13 When the left hanging rope 52 swings to the right, the hanging rope 52 is separated from the pressure on the moving roller 85, and the push rod 88 releases the limit of the gear sleeve 815. At this time, under the action of the reset spring 814, the moving tooth 816 is separated from the rack body 89. At this time, the compressed stop spring 82 rebounds quickly and drives the moving block 84 and the moving roller 85 to press the hanging rope 52 through the ejection plate 83, so that the moving roller 85 presses the hanging rope 52 against the fixed roller 87. At this time, the hanging rope 52 is bent by the pressure of the moving roller 85, and the moving roller 85 provides an upward pulling force for the hanging rope 52. At this time, the upward pulling force of the hanging rope 52 offsets the downward pulling force, thereby avoiding the tendency of the goods to shake.

[0058] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A double-hook intelligent gantry crane, characterized in that: The invention comprises a base plate (1), a support column (2) and a crossbeam (3); a fixed frame (4) is installed at the bottom of the crossbeam (3); a lifting assembly (5) is slidably installed in the fixed frame (4); an adjusting assembly (7) is installed on the fixed frame (4); the lifting assembly (5) comprises a roller (51); the adjusting assembly (7) comprises an intermittent gear (71) and a fixed rack (72); the intermittent gear (71) is coaxially installed with the roller (51); the fixed rack (72) is installed in the fixed frame (4); and the intermittent gear (71) is meshed with the fixed rack (72); The lifting assembly (5) is connected to the stop assembly (8) via a connecting assembly (9), the connecting assembly (9) comprising a connecting rod 1 (92) and a connecting rod 2 (93), the connecting rod 1 (92) connecting the stop assembly (8) and the fixed frame (4), and the connecting rod 2 (93) connecting the roller (51) and the stop assembly (8); The stop assembly (8) comprises a stop box (81) and a rope clamping box (86); a slide groove (91) is provided at the bottom of the fixed frame (4); one end of a connecting rod (92) is connected to the stop box (81); the other end of the connecting rod (92) is slidably matched with the slide groove (91); an annular groove (94) is provided on the roller (51); one end of a connecting rod (93) is connected to the rope clamping box (86); the other end of the connecting rod (93) is slidably matched with the annular groove (94); The stop assembly (8) further comprises an ejection plate (83), wherein the ejection plate (83) is connected to the stop box (81) via a stop spring (82), a moving block (84) is slidably mounted in the stop box (81), a moving roller (85) is mounted on one end of the moving block (84) away from the stop box (81), the moving roller (85) is slidably mounted in a rope clamping box (86), and a fixed roller (87) is fixedly mounted inside the rope clamping box (86).

2. A double-hook intelligent gantry crane according to claim 1, characterized in that: The fixed frame (4) is mounted with a pitch adjustment assembly (6), the pitch adjustment assembly (6) comprising a motor (61) and a positive and negative threaded rod (62), the positive and negative threaded rod (62) being mounted on the output shaft of the motor (61), the roller (51) being mounted with a transmission block (63), the transmission block (63) being in transmission cooperation with the positive and negative threaded rod (62).

3. A double-hook intelligent gantry crane according to claim 1, characterized in that: The stop box (81) is provided with a rack groove (810), a push groove (811) and an arc groove (813), respectively; a push rod (88) is installed on the moving block (84), and a rack body (89) is installed on the ejection plate (83); the push rod (88) and the rack body (89) are respectively located in the push groove (811) and the rack groove (810) for sliding.

4. A double-hook intelligent gantry crane according to claim 3, characterized in that: The arc groove (813) is connected to the gear sleeve (815) via a return spring (814), a moving tooth (816) is installed on the gear sleeve (815), the push rod (88) presses the gear sleeve (815), and the intermittent gear (71) is connected to the moving tooth (816) via a belt.

5. The double-hook intelligent gantry crane according to claim 1, characterized in that: The lifting assembly (5) further comprises a lifting rope (52) and a lifting hook (53). When the spacing between the lifting hooks (53) is adjusted, the lifting rope (52) is in a vertical state. When the lifting hook (53) lifts the cargo, the roller (51) rotates and reels, and the roller (51) drives the intermittent gear (71) to rotate synchronously. The intermittent gear (71) drives the roller (51) to move relative to the fixed rack (72), so that the lifting rope (52) pulls the cargo outward, and at this time, the lifting rope (52) is tilted.

6. The double-hook intelligent gantry crane according to claim 1, characterized in that: The crossbeam (3) comprises a transmission groove (31) and a transmission box (32); the fixed frame (4) is mounted on the bottom of the transmission box (32); the transmission groove (31) is provided on the side wall of the crossbeam (3); and the transmission box (32) slides along the transmission groove (31).

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