An air cooling device for CNC gantry milling machine

Abstract

The invention discloses an air cooling device for a CNC gantry milling machine in the field of machining technology, comprising a machine platform, a cutter head, a spindle, a nozzle and a refrigeration device, wherein the spindle is transmission-connected with the machine platform, the cutter head is arranged at the lower end of the spindle, the refrigeration device is arranged at one side of the spindle and is fixedly connected with the machine platform, the nozzle is connected to the lower end of the refrigeration device, and further comprises a transmission mechanism, which is transmission-connected with the spindle; an air intake mechanism, which is transmission-connected with the transmission mechanism and driven by the transmission mechanism; the invention effectively avoids unnecessary work of the air cooling device during operation, and at the same time, when the milling machine performs a small amount of high-speed rotation that exceeds the refrigeration capacity of the air cooling device, the air cooling device can perform high-power output accordingly, and since the operating power of the air cooling device changes continuously with the rotation speed of the cutter head, the high-power output time of the air cooling device is not frequent, which has little impact on the service life of the air cooling device.

Description

Technical Field

[0001] The invention relates to the technical field of machining, in particular to an air cooling device for a numerically controlled gantry milling machine. Background Art

[0002] When the milling machine is processing workpieces, some workpieces cannot be processed using water cooling. In order to protect the workpieces and the cutter head, air cooling is required to continuously cool the workpieces and the cutter head during the processing.

[0003] When the cutter head of a milling machine is processing a workpiece, as the speed of the cutter head increases, the heat generated in the process of the cutter head cutting the workpiece will gradually increase, and the traditional air cooling device cannot adaptively adjust the air volume according to the speed of the cutter head. This means that the traditional air cooling device will generate a large amount of unnecessary work when cooling. At the same time, for the sake of the service life of the device, the general output power of the traditional air cooling device will be less than its own maximum power. This means that when the milling machine is performing a small amount of high speed that exceeds the cooling capacity of the air cooling device, the air cooling device will not be able to effectively cool the machine, resulting in the cutter head being able to only perform low-speed processing or no processing at all.

[0004] Based on this, the present invention designs an air cooling device for a CNC gantry milling machine to solve the above problems. Summary of the invention

[0005] The object of the present invention is to provide an air cooling device for a CNC gantry milling machine, so as to solve the problem proposed in the above background technology that when the cutter head of the milling machine processes the workpiece, as the rotation speed of the cutter head increases, the heat generated in the process of the cutter head cutting the workpiece will gradually increase, and the traditional air cooling device cannot adaptively adjust the air output according to the rotation speed of the cutter head. This makes the traditional air cooling device generate a large amount of unnecessary work when cooling. At the same time, for the service life of the device, the general output power of the traditional air cooling device will be less than its own limit power. This makes the milling machine unable to effectively cool when performing a small amount of high rotation speed that exceeds the refrigeration capacity of the air cooling device, resulting in the problem that the cutter head can only perform low-speed processing or cannot process at all.

[0006] To achieve the above-mentioned object, the present invention provides the following technical solutions: an air cooling device for a CNC gantry milling machine, comprising a machine platform, a cutter head, a spindle, a nozzle and a refrigeration device, wherein the spindle is connected to the machine platform by transmission, the cutter head is arranged at the lower end of the spindle, the refrigeration device is arranged on one side of the spindle and is fixedly connected to the machine platform, the nozzle is connected to the lower end of the refrigeration device, and also comprises a transmission mechanism, which is connected to the spindle by transmission;

[0007] The air intake mechanism is connected to the transmission mechanism and driven by the transmission mechanism, and is used to inject compressed air into the refrigeration device.

[0008] As a further solution of the present invention, the transmission mechanism includes a synchronous wheel, the synchronous wheel is fixedly connected to the main shaft, the synchronous wheel is transmission-connected with a synchronous belt, and the synchronous belt is transmission-connected with the air intake mechanism.

[0009] As a further solution of the present invention, the air intake mechanism includes an air pump, which is fixedly connected to the machine, and the air pump is fixedly connected to a connecting pipe, and the connecting pipe is fixedly connected to a refrigeration device. The lower end of the air pump is transmission-connected to a transmission shaft, and the transmission shaft is transmission-connected to a transmission mechanism; the transmission shaft is transmission-connected to a speed changing mechanism, and the speed changing mechanism can change the transmission ratio of the main shaft to the transmission shaft. The connecting pipe is provided with a feedback mechanism, and the feedback mechanism is used to adjust the transmission ratio of the speed changing mechanism.

[0010] As a further scheme of the present invention, the speed change mechanism includes a conical synchronous wheel, a mounting frame is provided on the right side of the main shaft, the mounting frame is fixedly connected to the machine, the conical synchronous wheel is vertically arranged on the right side of the mounting frame, and a mounting cylinder is vertically fixedly connected to the upper right corner of the mounting frame, a slide plate is vertically slidably connected in the mounting cylinder, a first slide groove is vertically opened on the left side wall of the mounting cylinder, a slider is vertically slidably connected in the first slide groove, the slider is fixedly connected to the side wall of the slide plate, the lower end of the slide plate is rotatably connected to the upper end of the conical synchronous wheel, the lower end of the transmission shaft passes through the mounting cylinder and the slide plate and is fixedly connected to the upper end of the conical synchronous wheel, a spring is fixedly connected between the slide plate and the inner side wall of the upper end of the mounting cylinder, the conical synchronous wheel is connected to a synchronous belt transmission, a first fixed block is vertically fixedly connected to the upper end of the mounting frame, a first elastic telescopic rod is fixedly connected to the end of the first elastic telescopic rod, a tensioning wheel is rotatably provided at the end of the first elastic telescopic rod, the tensioning wheel is connected to the synchronous belt transmission, the slider is transmission-connected to a feedback mechanism, and the feedback mechanism is used to control the vertical displacement of the slider according to the air flow rate in the connecting pipe.

[0011] As a further solution of the present invention, a second fixed block is vertically fixedly connected to the right side of the upper end of the mounting frame, a second elastic telescopic rod is laterally fixedly connected to the left end of the second fixed block, a buckle is fixedly connected to the end of the second elastic telescopic rod, and the buckle engages the synchronous belt and is close to the side wall of the conical synchronous wheel.

[0012] As a further solution of the present invention, the feedback mechanism includes a mounting shell, which is fixedly connected to the outer wall of the connecting tube and is connected to the connecting tube; a fan blade is rotatably arranged in the mounting shell, half of the fan blade is exposed in the connecting tube, a rotating shaft is vertically fixedly connected to the axis of the fan blade, the lower end of the rotating shaft vertically penetrates the mounting shell and extends to the bottom of the mounting shell, a drum is fixedly connected to the lower end of the rotating shaft, a first rope is wound around the drum, the first rope is transmission-connected to a pulley group, the pulley group is transmission-connected to a second rope, and the second rope is fixedly connected to the upper end of the slider.

[0013] As a further solution of the present invention, the pulley group includes a mounting plate, a plurality of fixed pulleys arranged in an array are rotatably connected to the rear side of the upper end of the mounting plate, a second slide groove is longitudinally opened on the upper end of the mounting plate, a slide rod is longitudinally slidably connected to the second slide groove, and a plurality of movable pulleys arranged in an array are rotatably connected to the upper end of the slide rod, a third fixed block is fixedly connected to the right side of the upper end of the mounting plate, the first rope passes through each fixed pulley and movable pulley in turn and is fixedly connected to the third fixed block, the front end and right end of the mounting plate are rotatably connected to steering wheels, and the second rope passes through two steering wheels in turn and is fixedly connected to the front end of the slide rod.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The present invention provides an air intake mechanism whose working power can be increased as the rotation speed of the cutter head increases, so that the cooling effect of the equipment increases as the rotation speed of the cutter head increases, effectively avoiding unnecessary work of the air cooling device during the working process. At the same time, when the milling machine performs a small amount of high-speed operation that exceeds the refrigeration capacity of the air cooling device, the air cooling device can output high power accordingly. Since the operating power of the air cooling device changes continuously with the rotation speed of the cutter head, the high-power output time of the air cooling device is not frequent, which has little impact on the service life of the air cooling device.

[0016] The present invention provides a conical synchronous wheel capable of changing the transmission ratio, so that the greater the main shaft speed, the greater the transmission ratio between the main shaft and the transmission shaft, and thus after the power of the air pump is increased, the difficulty of the corresponding air pump to intake air increases, thereby compensating for the lack of air intake caused by the air pump;

[0017] The pulley block is horizontally laid on the mounting plate so that the gravity of the pulley block is supported by the mounting plate, thereby preventing the deadweight of the pulley block from interfering with the feedback of the feedback mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0019] Figure 2 This is a schematic diagram of the structure of the present invention after removing the machine platform;

[0020] Figure 3 for Figure 2 A schematic diagram of a half-section structure after removing the refrigeration device and part of the transmission mechanism;

[0021] Figure 4 for Figure 3 Schematic diagram of the structure after removing the air pump and connecting pipe;

[0022] Figure 5 for Figure 4 Schematic diagram of the cross-section structure.

[0023] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0024] The machine 11, the cutter head 12, the main shaft 13, the nozzle 14, the refrigeration device 15, the air pump 21, the connecting pipe 22, the transmission shaft 23, the synchronous wheel 31, the synchronous belt 32, the conical synchronous wheel 41, the mounting frame 42, the mounting tube 43, the slide plate 44, the first slide groove 45, the slider 46, the spring 47, the first fixed block 48, the first elastic telescopic rod 49, the tensioning wheel 410, the second fixed block 51, the second elastic telescopic rod 52, the buckle 53, the mounting shell 61, the fan blade 62, the rotating shaft 63, the reel 64, the first rope 65, the second rope 66, the mounting plate 71, the fixed pulley 72, the second slide groove 73, the slide rod 74, the movable pulley 75, the third fixed block 76, and the steering wheel 77. DETAILED DESCRIPTION

[0025] See also Figure 1-5 The present invention provides a technical solution: an air cooling device for a CNC gantry milling machine, comprising a machine table 11, a cutter head 12, a spindle 13, a nozzle 14 and a refrigeration device 15, wherein the spindle 13 is connected to the machine table 11 by transmission, the cutter head 12 is arranged at the lower end of the spindle 13, the refrigeration device 15 is arranged on one side of the spindle 13 and is fixedly connected to the machine table 11, the nozzle 14 is connected to the lower end of the refrigeration device 15, and also comprises a transmission mechanism, which is connected to the spindle 13 by transmission;

[0026] An air intake mechanism is in driving connection with the transmission mechanism and driven by the transmission mechanism, and is used for injecting compressed air into the refrigeration device 15 .

[0027] The machine 11 also includes a driving device in the milling machine. The machine 11 drives the main shaft 13 to rotate, and the main shaft 13 drives the cutter head 12 to cut the workpiece. At the same time, the main shaft 13 drives the air intake mechanism to work through the transmission mechanism. The air intake mechanism compresses the air and injects it into the refrigeration device 15. The refrigeration device 15 then sprays cold air between the cutter head 12 and the workpiece through the nozzle 14 to cool the cutter head 12 and the workpiece. In this process, as the speed of the main shaft 13 is faster, the corresponding speed of the cutter head 12 is faster, and the working power of the air intake mechanism is higher. Furthermore, as the speed of the cutter head 12 is faster, the working power of the air intake mechanism is higher, so that the speed at which the air intake mechanism injects compressed air into the refrigeration device 15 increases with the increase of the speed of the cutter head 12. Furthermore, the cold air sprayed by the nozzle 14 increases with the increase of the speed of the cutter head 12, so that the cooling effect of the equipment increases with the increase of the speed of the cutter head 12.

[0028] The present invention provides an air intake mechanism whose working power can be increased as the rotation speed of the cutter head 12 increases, so that the cooling effect of the equipment increases as the rotation speed of the cutter head 12 increases, effectively avoiding unnecessary work of the air cooling device during operation. At the same time, when the milling machine performs a small amount of high-speed operation that exceeds the refrigeration capacity of the air cooling device, the air cooling device can correspondingly output high power. Since the operating power of the air cooling device changes continuously with the rotation speed of the cutter head 12, the high-power output time of the air cooling device is not frequent, which has little impact on the service life of the air cooling device.

[0029] As a further solution of the present invention, the transmission mechanism includes a synchronous wheel 31, which is fixedly connected to the main shaft 13, and the synchronous wheel 31 is transmission-connected to a synchronous belt 32, and the synchronous belt 32 is transmission-connected to the air intake mechanism.

[0030] The main shaft 13 drives the synchronous wheel 31 to rotate, and the synchronous wheel 31 drives the air intake mechanism to work through the synchronous belt 32.

[0031] As a further solution of the present invention, the air intake mechanism includes an air pump 21, which is fixedly connected to the machine 11, and the air pump 21 is fixedly connected to a connecting pipe 22, and the connecting pipe 22 is fixedly connected to the refrigeration device 15. The lower end of the air pump 21 is transmission-connected to a transmission shaft 23, and the transmission shaft 23 is transmission-connected to the transmission mechanism; the transmission shaft 23 is transmission-connected to a speed changing mechanism, and the speed changing mechanism can change the transmission ratio from the main shaft 13 to the transmission shaft 23. The connecting pipe 22 is provided with a feedback mechanism, and the feedback mechanism is used to adjust the transmission ratio of the speed changing mechanism.

[0032] The transmission shaft 23 rotates to drive the air pump 21 to work, and the transmission mechanism drives the transmission shaft 23 to rotate, and changes the operating power of the air pump 21 by changing the rotation speed of the transmission shaft 23 .

[0033] As a further solution of the present invention, the speed change mechanism includes a conical synchronous wheel 41, a mounting frame 42 is provided on the right side of the main shaft 13, the mounting frame 42 is fixedly connected to the machine 11, the conical synchronous wheel 41 is vertically arranged on the right side of the mounting frame 42, a mounting cylinder 43 is vertically fixedly connected to the upper right side of the mounting frame 42, a slide plate 44 is vertically slidably connected in the mounting cylinder 43, a first slide groove 45 is vertically opened on the left side wall of the mounting cylinder 43, a slider 46 is vertically slidably connected in the first slide groove 45, the slider 46 is fixedly connected to the side wall of the slider 44, the lower end of the slider 44 is rotatably connected to the upper end of the conical synchronous wheel 41, and the lower end of the transmission shaft 23 is connected to the upper end of the conical synchronous wheel 41. The end passes through the mounting tube 43 and the slide plate 44 and is fixedly connected to the upper end of the conical synchronous wheel 41, a spring 47 is fixedly connected between the slide plate 44 and the inner side wall of the upper end of the mounting tube 43, the conical synchronous wheel 41 is transmission connected to the synchronous belt 32, the upper end of the mounting frame 42 is vertically fixedly connected to a first fixed block 48, the end of the first fixed block 48 is fixedly connected to a first elastic telescopic rod 49, the end of the first elastic telescopic rod 49 is rotatably provided with a tensioning wheel 410, the tensioning wheel 410 is transmission connected to the synchronous belt 32, the slider 46 is transmission connected to the feedback mechanism, and the feedback mechanism is used to control the vertical displacement of the slider 46 according to the air flow rate in the connecting pipe 22.

[0034] The tensioning wheel 410 stretches the synchronous belt 32 through the first elastic telescopic rod 49, so that the synchronous belt 32 can always maintain an effective transmission state with the synchronous wheel 31 and the conical synchronous wheel 41; in the process of the synchronous wheel 31 rotating with the main shaft 13, the synchronous wheel 31 drives the conical synchronous wheel 41 to rotate through the synchronous belt 32, and further the conical synchronous wheel 41 drives the air pump 21 to do work through the transmission shaft 23. In this process, under the action of the feedback mechanism, the more air flow is injected into the connecting pipe 22 by the air pump 21, the greater the air flow rate in the connecting pipe 22, and the corresponding feedback mechanism controls the upward displacement of the conical synchronous wheel 41 through the slider 46. Further, the transmission ratio between the main shaft 13 and the transmission shaft 23 is greater (as the power of the air pump 21 is greater, the corresponding air pump 21 is more difficult to intake air. Further, in order to make the air intake amount of the air pump 21 proportional to the rotation speed of the main shaft 13, so that the amount of cold air ejected can meet the equipment requirements, it is necessary to increase the transmission ratio between the main shaft 13 and the transmission shaft 23).

[0035] The present invention provides a conical synchronous wheel 41 capable of changing the transmission ratio, so that the greater the rotation speed of the main shaft 13, the greater the transmission ratio between the main shaft 13 and the transmission shaft 23. After the power of the air pump 21 is increased, the difficulty of the air pump 21 to intake air increases, thereby compensating for the lack of air intake by the air pump 21.

[0036] As a further solution of the present invention, a second fixed block 51 is vertically fixedly connected to the right side of the upper end of the mounting frame 42, a second elastic telescopic rod 52 is laterally fixedly connected to the left end of the second fixed block 51, and a buckle 53 is fixedly connected to the end of the second elastic telescopic rod 52, and the buckle 53 engages with the synchronous belt 32 and is close to the side wall of the conical synchronous wheel 41.

[0037] As the conical synchronous wheel 41 moves vertically, the corresponding conical synchronous wheel 41 applies friction force in the vertical direction to the synchronous belt 32 . At this time, the buckle 53 limits the synchronous belt 32 in the vertical direction to prevent the synchronous belt 32 from moving with the movement of the conical synchronous wheel 41 .

[0038] As a further solution of the present invention, the feedback mechanism includes a mounting shell 61, which is fixedly connected to the outer wall of the connecting tube 22 and is connected to the connecting tube 22; a fan blade 62 is rotatably arranged in the mounting shell 61, half of the fan blade 62 is exposed in the connecting tube 22, and a rotating shaft 63 is vertically fixedly connected to the axis of the fan blade 62, and the lower end of the rotating shaft 63 vertically penetrates the mounting shell 61 and extends to the bottom of the mounting shell 61, and the lower end of the rotating shaft 63 is fixedly connected to a reel 64, and a first rope 65 is wound around the reel 64, and the first rope 65 is transmission-connected to a pulley group, and the pulley group is transmission-connected to a second rope 66, and the second rope 66 is fixedly connected to the upper end of the slider 46.

[0039] The fan blades 62 are blown by the air flow in the connecting pipe 22, so that the fan blades 62 apply a certain torque to the rotating shaft 63, which further causes the rotating shaft 63 to drive the drum 64 to have a rotation tendency. The rotational force of the drum 64 is further transmitted to the second rope 66 through the first rope 65 and the pulley group, so that the second rope 66 pulls the slider 46 upward. In this process, the pulley group serves to amplify the rotational force of the drum 64, so that the rotational force of the drum 64 and the elastic force of the spring 47 are balanced through the pulley group.

[0040] As a further solution of the present invention, the pulley block includes a mounting plate 71, and a plurality of fixed pulleys 72 arranged in an array are rotatably connected to the rear side of the upper end of the mounting plate 71. A second slide groove 73 is longitudinally opened at the upper end of the mounting plate 71, and a slide rod 74 is longitudinally slidably connected to the second slide groove 73. A plurality of movable pulleys 75 arranged in an array are rotatably connected to the upper end of the slide rod 74. A third fixed block 76 is fixedly connected to the right side of the upper end of the mounting plate 71, and the first rope 65 passes around each fixed pulley 72 and the movable pulley 75 in turn and is fixedly connected to the third fixed block 76. The front end and right end of the mounting plate 71 are rotatably connected to a steering wheel 77, and the second rope 66 passes around the two steering wheels 77 in turn and is fixedly connected to the front end of the slide rod 74.

[0041] The pulley block is horizontally laid on the mounting plate 71 so that the gravity of the pulley block is supported by the mounting plate 71, thereby preventing the deadweight of the pulley block from interfering with the feedback of the feedback mechanism.

Claims

1. An air cooling device for a CNC gantry milling machine, comprising a machine platform (11), a cutter head (12), a spindle (13), a nozzle (14) and a refrigeration device (15), wherein the spindle (13) is drivingly connected to the machine platform (11), the cutter head (12) is arranged at the lower end of the spindle (13), the refrigeration device (15) is arranged on one side of the spindle (13) and is fixedly connected to the machine platform (11), and the nozzle (14) is connected to the lower end of the refrigeration device (15), characterized in that: It also includes a transmission mechanism, which is in transmission connection with the main shaft (13); An air intake mechanism, the air intake mechanism being in driving connection with the transmission mechanism and driven by the transmission mechanism, the air intake mechanism being used to inject compressed air into the refrigeration device (15); The transmission mechanism comprises a synchronous wheel (31), the synchronous wheel (31) is fixedly connected to the main shaft (13), the synchronous wheel (31) is drivingly connected to a synchronous belt (32), and the synchronous belt (32) is drivingly connected to the air intake mechanism; The air intake mechanism comprises an air pump (21), the air pump (21) is fixedly connected to the machine platform (11), the air pump (21) is fixedly connected to a connecting pipe (22), the connecting pipe (22) is fixedly connected to the refrigeration device (15), the lower end of the air pump (21) is drivingly connected to a transmission shaft (23), the transmission shaft (23) is drivingly connected to the transmission mechanism; the transmission shaft (23) is drivingly connected to a speed change mechanism, the speed change mechanism can change the transmission ratio from the main shaft (13) to the transmission shaft (23), the connecting pipe (22) is provided with a feedback mechanism, the feedback mechanism is used to adjust the transmission ratio of the speed change mechanism; The speed change mechanism comprises a conical synchronous wheel (41), a mounting frame (42) is arranged on the right side of the main shaft (13), the mounting frame (42) is fixedly connected to the machine platform (11), the conical synchronous wheel (41) is vertically arranged on the right side of the mounting frame (42), a mounting cylinder (43) is vertically fixedly connected to the upper right side of the mounting frame (42), a slide plate (44) is vertically slidably connected in the mounting cylinder (43), a first slide groove (45) is vertically opened on the left side wall of the mounting cylinder (43), a slide block (46) is vertically slidably connected in the first slide groove (45), the slide block (46) is fixedly connected to the side wall of the slide plate (44), the lower end of the slide plate (44) is rotatably connected to the upper end of the conical synchronous wheel (41), and the lower end of the transmission shaft (23) passes through the mounting cylinder (43). The cylinder (43) and the slide plate (44) are fixedly connected to the upper end of the conical synchronous wheel (41); a spring (47) is fixedly connected between the slide plate (44) and the inner side wall of the upper end of the mounting cylinder (43); the conical synchronous wheel (41) is transmission-connected to the synchronous belt (32); the upper end of the mounting frame (42) is vertically fixedly connected to a first fixed block (48); the end of the first fixed block (48) is fixedly connected to a first elastic telescopic rod (49); the end of the first elastic telescopic rod (49) is rotatably provided with a tensioning wheel (410); the tensioning wheel (410) is transmission-connected to the synchronous belt (32); the slider (46) is transmission-connected to a feedback mechanism; the feedback mechanism is used to control the vertical displacement of the slider (46) according to the air flow rate in the connecting pipe (22).

2. The air cooling device for a CNC gantry milling machine according to claim 1, characterized in that: A second fixing block (51) is vertically fixedly connected to the right side of the upper end of the mounting frame (42); a second elastic telescopic rod (52) is transversely fixedly connected to the left end of the second fixing block (51); a buckle (53) is fixedly connected to the end of the second elastic telescopic rod (52); the buckle (53) is engaged with the synchronous belt (32) and is closely attached to the side wall of the conical synchronous wheel (41).

3. The air cooling device for a CNC gantry milling machine according to claim 2, characterized in that: The feedback mechanism comprises a mounting shell (61), wherein the mounting shell (61) is fixedly connected to the outer wall of the connecting tube (22) and is connected to the connecting tube (22); a fan blade (62) is rotatably arranged in the mounting shell (61), wherein half of the fan blade (62) is exposed in the connecting tube (22); a rotating shaft (63) is vertically fixedly connected to the axis of the fan blade (62); the lower end of the rotating shaft (63) vertically penetrates the mounting shell (61) and extends to the bottom of the mounting shell (61); the lower end of the rotating shaft (63) is fixedly connected to a reel (64); a first rope (65) is wound around the reel (64); the first rope (65) is transmission-connected to a pulley block; the pulley block is transmission-connected to a second rope (66); the second rope (66) is fixedly connected to the upper end of the slider (46).

4. The air cooling device for a CNC gantry milling machine according to claim 3, characterized in that: The pulley block comprises a mounting plate (71), a plurality of fixed pulleys (72) arranged in an array are rotatably connected to the rear side of the upper end of the mounting plate (71), a second slide groove (73) is longitudinally opened at the upper end of the mounting plate (71), a slide rod (74) is longitudinally slidably connected to the second slide groove (73), a plurality of movable pulleys (75) arranged in an array are rotatably connected to the upper end of the slide rod (74), a third fixed block (76) is fixedly connected to the right side of the upper end of the mounting plate (71), the first rope (65) passes through each of the fixed pulleys (72) and the movable pulley (75) in sequence and is fixedly connected to the third fixed block (76), the front end and the right end of the mounting plate (71) are rotatably connected to a steering wheel (77), the second rope (66) passes through two steering wheels (77) in sequence and is fixedly connected to the front end of the slide rod (74).

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