Synchronously-driven multi-rope parallel hoisting mechanism

Abstract

The invention discloses a synchronously-driven multi-rope parallel hoisting mechanism which comprises a truss and a moving frame installed on the truss, the position of the moving frame on the truss can be adjusted, a lifting plate is connected to the moving frame through at least two ropes, the end, away from the lifting plate, of one rope is installed on a reel, and the other end, away from the lifting plate, of the other rope is installed on the other reel. Different from the prior art, the winding shafts are vertically and rotatably installed on the movable frame, the winding device further comprises a first transmission mechanism arranged between the at least two winding shafts, and the first transmission mechanism is used for achieving synchronous rotation of the at least two winding shafts. An elastic pulling mechanism is arranged between the lifting plate and the moving frame and used for ensuring that the rope located between the lifting plate and the moving frame is in a stretched state. According to the device, synchronous rotation of at least two ropes can be achieved, the elastic pulling mechanism is used for ensuring that the ropes located between the lifting plate and the moving frame are in a stretching state, and then the overall stability of the device is improved.

Description

Technical Field

[0001] The invention relates to the technical field of a lifting mechanism of a crane, and in particular to a synchronously driven multi-rope parallel lifting mechanism. Background Art

[0002] Existing cranes are widely used in the construction, manufacturing, ports, warehousing and other industries, and are suitable for heavy object handling and hoisting operations. Especially in the construction industry, single-rope or double-rope drive is usually used, which has a simple structure and relatively low cost; while in the port and warehousing industries, four-rope drive is used for the stability and anti-interference ability of hoisting. They mainly drive the transmission shaft with a wire groove fixed through the motor and coupling. The end of the wire rope is fixed in the wire groove, and the forward and reverse rotation of the motor drives the wire groove to complete the action of winding and releasing the wire. Compared with the single-rope or double-rope system, the four-rope drive design provides better load distribution and can effectively reduce the risk of tilting of the crane during high-altitude operations.

[0003] The objective disadvantages of the traditional four-rope drive lifting device are mainly reflected in the wire-receiving mechanism. The structure of the common four-rope wire-receiving mechanism is simple and the stability is low. When the free end of the rope is loaded in the traditional wire-receiving mechanism, due to the uncertainty of the force of a single rope, it is easily disturbed by factors of the external environment, and the free end load object is easily swung, which reduces the fatigue strength of the rope and causes the rope to break, bringing safety hazards to the production environment. Secondly, the traditional four-rope wire-receiving mechanism usually uses multiple power sources to realize the retraction and release of the rope, which has extremely high requirements for the coordination control and accuracy between each power source, and has a great impact on the synchronization of the retraction and release of the four ropes. At the same time, the winding mechanism in the traditional four-rope wire-receiving mechanism has only simple rotary winding, and has no function of wiring, which will cause entanglement and knotting when the rope is retracted and released, affecting the stability and work efficiency of the system. In addition, there is a lack of rigid support between the wire-receiving part and the end effector of the traditional lifting device. The tension and stiffness provided by the flexible support such as the rope are not enough to cope with the disturbance of external factors (such as wind force, operation acceleration, etc.). Summary of the invention

[0004] In order to solve the technical problems existing in the background technology, the present invention proposes a synchronously driven multi-rope parallel lifting mechanism.

[0005] The present invention proposes a synchronously driven multi-rope parallel lifting mechanism, comprising a truss and a mobile frame mounted on the truss, wherein the position of the mobile frame on the truss can be adjusted, and the mobile frame is connected with a lifting plate via at least two ropes, and one end of each rope away from the lifting plate is mounted on a reel, and the difference from the prior art is that the reel is vertically rotatably mounted on the mobile frame, and further comprising a first transmission mechanism arranged between at least two reels, wherein the first transmission mechanism is used to realize synchronous rotation of at least two reels;

[0006] An elastic pulling mechanism is provided between the lifting plate and the moving frame, and the elastic pulling mechanism is used to ensure that the rope between the lifting plate and the moving frame is in a stretched state.

[0007] As a further optimized solution of the present invention, the elastic pulling mechanism includes multiple groups of elastic connecting shaft assemblies, the multiple groups of elastic connecting shaft assemblies are distributed in the vertical direction, and a scissor fork mechanism is provided between any two adjacent groups of the elastic connecting shaft assemblies;

[0008] The elastic connecting shaft assembly includes an outer transverse axis and an inner transverse axis that are arranged oppositely and in parallel, an elastic member is arranged between the outer transverse axis and the inner transverse axis, and the scissor fork mechanism includes the first connecting rod and the second connecting rod, the middle parts of the first connecting rod and the second connecting rod are connected by a rotating shaft in a transverse rotation, one end of the first connecting rod is transversely rotated and installed on the outer transverse axis of the elastic connecting shaft assembly located below, the other end of the first connecting rod is transversely rotated and installed on the inner transverse axis of the elastic connecting shaft assembly located above, one end of the second connecting rod is transversely rotated and installed on the inner transverse axis of the elastic connecting shaft assembly located below, and the other end of the second connecting rod is transversely rotated and installed on the outer transverse axis of the elastic connecting shaft assembly located above. The scissor fork mechanism can further improve stability and reduce the impact of external interference on equipment performance while meeting the lifting requirements.

[0009] As a further optimized solution of the present invention, the outer transverse axis and the inner transverse axis located at the top are both installed on the movable frame for transverse sliding; the outer transverse axis and the inner transverse axis located at the bottom are installed on the lifting plate for transverse sliding.

[0010] As a further optimized solution of the present invention, two groups of the scissor-fork mechanisms are provided between any two adjacent groups of the elastic connecting shaft assemblies, and the two groups of the scissor-fork mechanisms are arranged parallel to each other at both ends of the outer horizontal axis and the inner horizontal axis.

[0011] As a further optimized solution of the present invention, the elastic member is located between the two groups of the scissor fork mechanisms.

[0012] As a further optimized solution of the present invention, when the angle between the first connecting rod and the second connecting rod is the smallest, the elastic member is in an original length or an extended state.

[0013] As a further optimized solution of the present invention, a connecting piece for fixing the rope is provided on the lifting plate, and the connecting piece is ring-shaped and vertically rotatably mounted on the lifting plate.

[0014] As a further optimized solution of the present invention, the first transmission mechanism includes the driving shaft vertically mounted on the movable frame, the driving shaft is provided with a driving gear, each of the reels is provided with a driven gear meshing with the driving gear, and the rotation of the driving shaft drives at least two of the reels to rotate synchronously through the driving gear and the driven gear.

[0015] As a further optimized solution of the present invention, a rope guide is also provided on the movable frame through a reciprocating screw slider mechanism. When the rope on the reel is paid out or reeled in, the reciprocating screw slider mechanism is used to drive the rope guide to reciprocate in the vertical direction to achieve combing of the rope.

[0016] As a further optimized solution of the present invention, the reciprocating screw slider mechanism includes a reciprocating screw vertically rotatably mounted on the movable frame, a second transmission mechanism is provided between the reciprocating screw and the reel, and the reel drives the reciprocating screw to rotate through the second transmission mechanism.

[0017] In the present invention, the proposed synchronously driven multi-rope parallel lifting mechanism can realize the synchronous rotation of at least two ropes through the setting of the first transmission mechanism, and the elastic pulling mechanism is used to ensure that the ropes located between the lifting plate and the moving frame are in a stretched state, thereby increasing the overall stability of the device.

[0018] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the structure of the present invention;

[0020] Figure 2 It is a partial enlarged view of the first transmission mechanism of the present invention;

[0021] Figure 3 It is a partial enlarged view of the second transmission mechanism of the present invention;

[0022] Figure 4 This is a schematic diagram of the structure of the mobile rack of the present invention;

[0023] Figure 5 It is a partial enlarged view of the elastic connecting shaft assembly of the present invention;

[0024] In the figure: 1. truss; 2. lifting plate; 3. rope; 4. reel; 5. first horizontal moving mechanism; 6. second horizontal moving mechanism; 7. elastic connecting shaft assembly; 70. outer horizontal shaft; 71. inner horizontal shaft; 72. elastic member; 73. scissor fork mechanism; 730. first connecting rod; 731. second connecting rod; 8. fixed pulley; 9. connecting member; 10. first limiting plate; 11. second limiting plate; 12. driving gear; 13. driven gear; 14. reciprocating screw slider mechanism; 15. rope guide; 16. second transmission mechanism; 17. moving frame. DETAILED DESCRIPTION

[0025] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar symbols throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0026] like Figure 1-Figure 5 A synchronously driven multi-rope parallel lifting mechanism is shown, comprising a truss 1 and a moving frame 17 mounted on the truss 1, wherein the position of the moving frame 17 on the truss 1 can be adjusted, wherein the moving frame 17 is connected to a lifting plate 2 via at least two ropes 3, wherein one end of the rope 3 away from the lifting plate 2 is mounted on a reel 4, and the reel 4 is vertically rotatably mounted on the moving frame 17, and further comprising a first transmission mechanism disposed between at least two reels 4, wherein the first transmission mechanism is used to realize synchronous rotation of at least two reels 4;

[0027] An elastic pulling mechanism 7 is provided between the lifting plate 2 and the moving frame 17 , and the elastic pulling mechanism 7 is used to ensure that the rope 3 between the lifting plate 2 and the moving frame 17 is in a stretched state.

[0028] Specifically, in some embodiments, the truss 1 is provided with a first horizontal moving mechanism 5 , which is used to drive the moving frame 17 to move in a horizontal direction, so as to adjust the position of the moving frame 17 relative to the truss 1 .

[0029] In some embodiments, preferably, the truss 1 is also provided with a second horizontal moving mechanism 6, which is installed at the moving end of the first horizontal moving mechanism 5, and the displacement of the second horizontal moving mechanism 6 relative to the truss 1 is perpendicular to the displacement of the first horizontal moving mechanism 5 relative to the truss 1, and the moving frame 17 is installed on the second horizontal moving frame 17, so as to facilitate the adjustment of the position of the moving frame 17 relative to the truss 1 to facilitate the movement of materials.

[0030] It should be noted that the first horizontal moving mechanism 5 and the second horizontal moving mechanism 6 can be a screw slider mechanism or an electric cylinder or a pneumatic cylinder in the prior art that can drive the components to move horizontally. In this embodiment, the first horizontal moving mechanism 5 and the second horizontal moving mechanism 6 are both screw slider moving mechanisms.

[0031] It should be noted that the elastic pulling mechanism 7 can be a spring in the prior art, which is fixed between the movable frame 17 and the lifting plate 2, and when the lifting plate 2 is in the lowest position, the spring is in the original length state or the compressed state. When the reel 4 rotates to drive the lifting plate 2 to move upward, the spring is compressed, thereby ensuring that the rope 3 is in a stretched state.

[0032] In order to prevent the lifting plate 2 from shaking relatively greatly relative to the moving frame 17 during the moving process, Figure 5 As shown, in some embodiments, preferably, the elastic pulling mechanism 7 includes multiple groups of elastic connecting shaft assemblies, the multiple groups of elastic connecting shaft assemblies are distributed in the vertical direction, and a scissor fork mechanism 73 is provided between any two adjacent groups of the elastic connecting shaft assemblies;

[0033] The elastic connecting shaft assembly includes an outer transverse shaft 70 and an inner transverse shaft 71 which are arranged oppositely and in parallel, an elastic member 72 is arranged between the outer transverse shaft 70 and the inner transverse shaft 71, and the scissor fork mechanism 73 includes a first connecting rod 730 and a second connecting rod 731, the middle parts of the first connecting rod 730 and the second connecting rod 731 are connected to each other in transverse rotation through a rotating shaft, one end of the first connecting rod 730 is transversely rotatably mounted on the outer transverse shaft 70 of the elastic connecting shaft assembly located below, the other end of the first connecting rod 730 is transversely rotatably mounted on the inner transverse shaft 71 of the elastic connecting shaft assembly located above, one end of the second connecting rod 731 is transversely rotatably mounted on the inner transverse shaft 71 of the elastic connecting shaft assembly located below, and the other end of the second connecting rod 731 is transversely rotatably mounted on the outer transverse shaft 70 of the elastic connecting shaft assembly located above;

[0034] The outer transverse shaft 70 and the inner transverse shaft 71 at the top are both installed on the moving frame 17 for transverse sliding; the outer transverse shaft 70 and the inner transverse shaft 71 at the bottom are installed on the lifting plate 2 for transverse sliding;

[0035] Specifically, T-slots are provided on the upper moving frame 17 and the lifting plate 2, and T-slot sliders matching the T-slots are provided on the inner transverse axis 71 and the outer transverse axis 70 located at the top and the bottom, so as to realize the relative movement of the transverse axis (including the inner transverse axis 71 and the outer transverse axis 70) relative to the lifting plate 2 and the moving frame 17 and prevent the transverse axis from being separated from the lifting plate 2 and the moving frame 17 (the T-slots and the T-slot sliders are not shown in the figure);

[0036] Two groups of scissor fork mechanisms 73 are provided between any two adjacent groups of elastic connecting shaft assemblies, and the two groups of scissor fork mechanisms 73 are arranged parallel to each other at both ends of the outer horizontal axis 70 and the inner horizontal axis 71; and in order to achieve a better effect, the elastic member 72 is located between the two groups of scissor fork mechanisms 73, and two groups of elastic members 72 are provided, and the two groups of elastic members 72 are distributed along the axial direction of the outer horizontal axis 70 or the inner horizontal axis 71, thereby further increasing stability.

[0037] Preferably, when the angle between the first connecting rod 730 and the second connecting rod 731 is the smallest, the elastic member 72 is in the original length or extended state, and then when the lifting plate 2 moves upward, the elastic member 72 is stretched, and the rope 3 is ensured to be in the stretched state under the action of the elastic member 72.

[0038] In some embodiments, preferably, a fixed pulley 8 is installed on the movable frame 17 for horizontal rotation, and at least two fixed pulleys 8 are provided, one fixed pulley 8 corresponds to one reel 4, and the rope 3 on each reel 4 passes around a fixed pulley 8 before being connected to the lifting plate 2.

[0039] In some embodiments, preferably, the lifting plate 2 is provided with a connecting piece 9 for fixing the rope 3, and the connecting piece 9 is ring-shaped. To facilitate the connection of the rope 3 to the lifting plate 2, the connecting piece 9 is provided with at least two groups, and one group of connecting pieces 9 is connected to one rope 3.

[0040] In this embodiment, there are four ropes 3, four connecting members 9, and four sets of corresponding fixed pulleys 8.

[0041] Preferably, the connecting member 9 is vertically rotatably mounted on the lifting plate 2 to further increase its overall stability.

[0042] Specifically, each reel 4 is provided with a first limiting plate 10 and a second limiting plate 11 , a rope 3 winding space is formed between the first limiting plate 10 and the second limiting plate 11 , and the rope 3 wound on the reel 4 is located between the first limiting plate 10 and the second limiting plate 11 .

[0043] In some embodiments, preferably, the first transmission mechanism includes a driving shaft vertically mounted on a mobile frame 17, a driving gear 12 is provided on the driving shaft, and each reel 4 is provided with a driven gear 13 meshing with the driving gear 12. The rotation of the driving shaft drives at least two reels 4 to rotate synchronously in the same direction through the driving gear 12 and the driven gear 13.

[0044] Specifically, the mobile frame 17 is also provided with a driving mechanism, which drives the driving shaft to rotate. The driving mechanism can be a motor in the prior art, or can be a motor in the prior art used in conjunction with a belt transmission mechanism. In the present embodiment, the motor drives the main shaft to rotate through the belt transmission mechanism.

[0045] In some embodiments, preferably, a rope guide 15 is also provided on the moving frame 17 through a reciprocating screw slider mechanism 14. The reciprocating screw slider mechanism 14 includes a reciprocating screw and a slider. The reciprocating screw is vertically rotatably installed on the moving frame 17. The slider is installed on the reciprocating screw and the rotation of the reciprocating screw drives the slider to reciprocate in the vertical direction relative to the moving frame 17. The rope guide 15 is fixed on the slider, and a through hole is opened on the rope guide 15. The rope 3 passes through the through hole of the rope guide 15. The stroke of the slider is equal to the distance between the first limit plate 10 and the second limit plate 11. The rope guide 15 is used to comb the rope 3 wound on the reel 4 to prevent the rope 3 from being wound around a position on the reel 4.

[0046] Preferably, a second transmission mechanism 16 is provided between the screw and the reel 4, and the reel 4 rotates to drive the reciprocating screw to rotate through the second transmission mechanism 16, thereby guiding the rope 3 when the reel 4 unwinds or winds the rope 3. The second transmission mechanism 16 is a belt transmission mechanism.

[0047] There are at least two groups of reciprocating screw slider mechanisms 14 and rope guides 15. One group of rope guides 15 is installed on a reciprocating screw slider mechanism 14. A reciprocating screw slider mechanism 14 corresponds to a reel 4. A group of second transmission mechanisms 16 is provided between a reel 4 and a reciprocating screw.

[0048] Specifically, during the working process, the driving mechanism drives the active shaft to rotate, and the active shaft drives at least two reels 4 to rotate synchronously through the active gear 12 and the driven gear 13, thereby realizing the unwinding or winding of the rope 3 on the reel 4, and the reel 4 drives the reciprocating screw slider mechanism 14 to move through the second transmission mechanism 16, thereby realizing the combing of the rope 3 by the rope guide 15; and when the rope 3 is unwinding or winding, it drives the lifting plate 2 to move in the vertical direction, and when the lifting plate 2 moves, it drives the scissors fork mechanism 73 to move and at the same time drives the change of the distance between the outer horizontal axis 70 and the inner horizontal axis 71, while improving the overall stability and anti-interference ability of the device, ensuring that the lifting plate 2 can maintain stable movement under high load and complex working conditions.

[0049] It should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0050] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0051] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0052] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0053] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A synchronously driven multi-rope parallel lifting mechanism, comprising a truss (1) and a moving frame (17) mounted on the truss (1), wherein the moving frame (17) is connected to a lifting plate (2) via at least two ropes (3), and each of the ropes (3) is mounted on a reel (4) at one end away from the lifting plate (2), characterized in that: The reel (4) is vertically rotatably mounted on the mobile frame (17), and further comprises a first transmission mechanism arranged between at least two reels (4), wherein the first transmission mechanism is used to realize synchronous rotation of at least two reels (4); An elastic pulling mechanism (7) is provided between the lifting plate (2) and the moving frame (17), and the elastic pulling mechanism (7) is used to ensure that the rope (3) between the lifting plate (2) and the moving frame (17) is in a stretched state.

2. The synchronously driven multi-rope parallel hoisting mechanism according to claim 1, characterized in that: The elastic pulling mechanism (7) comprises a plurality of groups of elastic connecting shaft assemblies, the plurality of groups of elastic connecting shaft assemblies are distributed in the vertical direction, and a scissor fork mechanism (73) is provided between any two adjacent groups of the elastic connecting shaft assemblies; The elastic connecting shaft assembly comprises an outer transverse shaft (70) and an inner transverse shaft (71) which are arranged oppositely and in parallel, an elastic member (72) is arranged between the outer transverse shaft (70) and the inner transverse shaft (71), the scissor fork mechanism (73) comprises a first connecting rod (730) and a second connecting rod (731), the middle parts of the first connecting rod (730) and the second connecting rod (731) are connected in transverse rotation through a rotating shaft, one end of the first connecting rod (730) is transversely rotationally mounted on the outer transverse shaft (70) of the elastic connecting shaft assembly located below, the other end of the first connecting rod (730) is transversely rotationally mounted on the inner transverse shaft (71) of the elastic connecting shaft assembly located above, one end of the second connecting rod (731) is transversely rotationally mounted on the inner transverse shaft (71) of the elastic connecting shaft assembly located below, and the other end of the second connecting rod (731) is transversely rotationally mounted on the outer transverse shaft (70) of the elastic connecting shaft assembly located above.

3. The synchronously driven multi-rope parallel hoisting mechanism according to claim 2, characterized in that: The outer transverse axis (70) and the inner transverse axis (71) located at the top are both installed on the movable frame (17) in a transverse sliding manner; the outer transverse axis (70) and the inner transverse axis (71) located at the bottom are installed on the lifting plate (2) in a transverse sliding manner.

4. The synchronously driven multi-rope parallel hoisting mechanism according to claim 2, characterized in that: Two groups of the scissor-fork mechanisms (73) are provided between any two adjacent groups of the elastic connecting shaft assemblies, and the two groups of the scissor-fork mechanisms (73) are arranged parallel to each other at both ends of the outer transverse axis (70) and the inner transverse axis (71).

5. The synchronously driven multi-rope parallel hoisting mechanism according to claim 4, characterized in that: The elastic member (72) is located between the two sets of scissor-fork mechanisms (73).

6. The synchronously driven multi-rope parallel hoisting mechanism according to claim 2, characterized in that: When the angle between the first connecting rod (730) and the second connecting rod (731) is the smallest, the elastic member (72) is in an original length or extended state.

7. The synchronously driven multi-rope parallel hoisting mechanism according to claim 1, characterized in that: The lifting plate (2) is provided with a connecting piece (9) for fixing the rope (3); the connecting piece (9) is ring-shaped and is vertically rotatably mounted on the lifting plate (2).

8. The synchronously driven multi-rope parallel hoisting mechanism according to claim 1, characterized in that: The first transmission mechanism comprises a driving shaft mounted vertically on the moving frame (17), the driving shaft being provided with a driving gear (12), each of the reels (4) being provided with a driven gear (13) meshing with the driving gear (12), and the driving shaft rotating through the driving gear (12) and the driven gear (13) driving at least two reels (4) to rotate synchronously.

9. The synchronously driven multi-rope parallel hoisting mechanism according to claim 1, characterized in that: A rope guide (15) is also provided on the movable frame (17) via a reciprocating screw rod slider mechanism (14). When the rope (3) on the reel (4) is unwinding or winding, the reciprocating screw rod slider mechanism is used to drive the rope guide (15) to reciprocate in the vertical direction to achieve combing of the rope (3).

10. The synchronously driven multi-rope parallel hoisting mechanism according to claim 1, characterized in that: The reciprocating screw slider mechanism (14) comprises a reciprocating screw which is vertically rotatably mounted on the moving frame (17); a second transmission mechanism (16) is provided between the reciprocating screw and the reel (4); and the reel (4) drives the reciprocating screw to rotate via the second transmission mechanism (16).

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