CN220096756U - Automatic mesh bag dotting packagine machine's dotting mechanism that has anti-sticking device - Google Patents

Abstract

The utility model discloses a buckling mechanism with an anti-blocking device of an automatic mesh bag buckling packaging machine, which comprises a frame and a buckling and cutting device, wherein the buckling and cutting device comprises a folding mechanism and a sealing and cutting mechanism, the folding mechanism is rotationally fixed through a supporting block arranged on the frame, a left cantilever is rotationally fixed on the supporting block through a left suspension shaft, a right cantilever is rotationally fixed on the supporting block through a right suspension shaft, and the sealing and cutting mechanism is installed and fixed on the right cantilever. When one bag is packed, the iron wire bound at the upper end of the net bag forms the iron buckle which can naturally fall off from the buckling mould along with the packing object under the action of gravity, the iron buckle bound at the lower end of the unpacked empty bag of the next bag stays in the buckling mould, when the folding mechanism is opened, the iron buckle can incline in the mould to be blocked, the frequency of the phenomenon is 3/1000 in actual production, and the anti-blocking device thoroughly eliminates the phenomenon.

Description

Automatic mesh bag dotting packagine machine's dotting mechanism that has anti-sticking device

Technical Field

The utility model belongs to the technical field of mesh bag packaging machines, and particularly relates to a buckling mechanism with an anti-jamming device of an automatic mesh bag buckling packaging machine.

Background

The net bag is a net bag which is formed by braiding wires and is used for storing articles. In the traditional technology, vegetables and fruits are packed in a packing net or a packing bag in a manual packing mode, one end of the packing net or the packing bag is folded and sealed by hands, the vegetables and fruits are placed in the packing net or the packing bag from the other end, and then the packing net or the packing bag is folded and sealed by hands. There is a barrel type pocket for packing fruit vegetables in the market, and the bag body of barrel type pocket includes barrel type omentum and piece formula complex film, is used for placing fruit vegetables in the barrel type omentum, and piece formula complex film is attached in the partial region in the omentum outside, and conventional packagine machine is when unloading fruit vegetables material to barrel type pocket in, and the phenomenon that the bag body sags, leads to sack and unloading end to take place dislocation appears behind barrel type pocket receives fruit vegetables material weight. The automatic mesh bag buckling packaging machine mainly comprises the steps of buckling the mesh bag, and then buckling and cutting the mesh bag through a buckling and cutting mechanism to form an upper iron buckle and a lower iron buckle on the mesh bag and cut off the middle of the upper iron buckle and the lower iron buckle to realize automatic packaging. When one bag is packed, the iron buckle tied at the upper end of the net bag falls off naturally from the buckle forming die along with the packing object under the action of gravity, and the iron buckle tied at the lower end of the unpacked empty bag of the next bag stays in the buckle forming die, and when the folding mechanism is opened, the iron buckle is pulled out from the die. However, when the closure mechanism of the buckling mould is opened, the iron buckle is likely to incline in the mould to be blocked, so that the packaging of the next net bag is affected.

Disclosure of Invention

Aiming at least one defect in the prior art, the utility model provides a buckling mechanism with an anti-jamming device of an automatic mesh bag buckling packaging machine, which can thoroughly avoid the jamming phenomenon in actual production by arranging a buckling cutting and anti-jamming device and a taper hole mechanism matched with the buckling cutting and anti-jamming device to fast buckle and cut off the mesh bag.

In order to achieve the above purpose, the present utility model provides the following technical solutions:

the automatic mesh bag buckling packaging machine comprises a buckling mechanism with an anti-blocking device, and comprises a frame and a buckling and cutting device arranged on the frame, wherein the buckling and cutting device comprises a gathering mechanism and a sealing and cutting mechanism which is matched with the gathering mechanism for use; the folding mechanism comprises an air cylinder, a left cantilever and a right cantilever, the folding mechanism is rotationally fixed through a supporting block arranged on the frame, the left cantilever is rotationally fixed on the supporting block through a left suspension shaft, and the right cantilever is rotationally fixed on the supporting block through a right suspension shaft; the sealing and cutting mechanism is fixedly arranged on the right cantilever and comprises a taper hole mechanism, an oil cylinder, an upper driving rod and a lower driving rod; one end of the upper driving rod is movably connected with one end of the lower driving rod through an oil cylinder rod arranged in the oil cylinder to control the taper hole mechanism to buckle and cut off the mesh bag; the tail of the right cantilever is movably connected with the cylinder rod arranged in the cylinder, the tail of the cylinder is fixed on the frame through a fixed shaft, when the mesh bag is packed, the cylinder rod is contracted to enter the cylinder, the right cantilever is pulled to rotate around the right cantilever shaft to enable the buckling and cutting device to be in an open state, when the mesh bag is buckled and cut off, the cylinder rod of the cylinder stretches out to push the right cantilever to rotate around the right cantilever shaft to enable the buckling and cutting device to be in a closed state, and after the cylinder rod is driven by hydraulic oil, the cylinder rod pushes the upper driving rod and the lower driving rod to rotate at the taper hole mechanism to buckle the mesh bag up and down, and then the middle of the mesh bag is cut off.

Preferably, the folding mechanism further comprises a right auxiliary arm, one end of which is mutually perpendicular to the rear end part of the right cantilever, and the other end of the right auxiliary arm is rotationally connected with the supporting block through the right cantilever shaft; thereby increasing the rotation amplitude of the folding mechanism and facilitating the folding of the net bag into the buckling and cutting-off area.

Further, the cylinder rod is arranged at the bottom of the rear end part of the right cantilever through a chain ring, and the right cantilever is further provided with a furling plate and a limiting plate matched with the furling plate for use, so that the mesh bag is prevented from swinging in the furling process.

Preferably, a vertically-through crack space for accommodating the mesh bag is formed between the folding plate and the limiting plate, and the taper hole mechanism is positioned on the side wall of the crack and is opposite to the left cantilever, so that the mesh bag can conveniently enter the taper hole mechanism under the pushing of the left cantilever after being folded.

The taper hole mechanism comprises an upper buckling die, a lower buckling die and a cutter, wherein the cutter is positioned between the upper buckling die and the lower buckling die, iron wires are fed into the upper buckling die and the lower buckling die through a paying-off device to buckle and tighten the net bags, the cutter cuts off from the middle to separate the net bags, and the upper net bags continue to pack vegetables and fruits.

Further, a connecting rod is arranged between the left cantilever and the right auxiliary arm, when the right auxiliary arm is pushed to rotate around the right cantilever shaft by the expansion and contraction of the cylinder rod, the right auxiliary arm drives the connecting rod to push the left cantilever to rotate around the left cantilever shaft so as to realize the opening and closing of the folding mechanism, and in the folding process of the mesh bag, the mesh bag is close to the right cantilever and stable, is not easy to skew, and the buckling and cutting-off positions are accurate.

Further, the left cantilever further comprises an upper plate and a lower plate matched with the upper plate, and anti-blocking devices are respectively arranged on one sides, close to the mesh bags, of the bottoms of the upper plate and the lower plate; the anti-blocking device comprises an upper arm and a lower arm, wherein the upper arm and the lower arm are respectively arranged on the upper plate through fixing columns; the tail parts of the upper arm and the lower arm are elastically fixed through springs, the front ends of the upper arm and the lower arm are preferentially contacted with the mesh bag when the upper arm and the lower arm rotate along with the left cantilever to be close to the mesh bag, and the upper arm and the lower arm are in a force application state for the mesh bag under the action of the stretching of the springs in the process of folding the mesh bag; when the mesh bag is buckled and cut off, the left cantilever opens the front upper arm and the lower arm to push the mesh bag open preferentially, so that the mesh bag is separated faster, and the clamping stagnation phenomenon is thoroughly avoided.

Compared with the prior art, the utility model has the advantages that:

1. when the net bag is packed, the cylinder rod is contracted to enter the cylinder, the right cantilever is pulled to rotate around the right suspension shaft to enable the buckling and cutting device to be in an open state, when the net bag is buckled and cut off, the cylinder rod of the cylinder stretches out to push the right cantilever to rotate around the right suspension shaft to enable the buckling and cutting device to be in a closed state, and after the cylinder rod is driven by hydraulic oil to push the upper driving rod and the lower driving rod to rotate at the taper hole mechanism to buckle the net bag up and down, the middle of the net bag is cut off and separated. The anti-blocking device has simple structure and low cost; when one bag is packed, iron wires bound at the upper end of the net bag form iron buttons which can naturally fall off from a buckling mould along with the packing objects under the action of gravity, the iron buttons bound at the lower end of an unpacked empty bag of the next bag stay in the buckling mould, when a folding mechanism is opened, the iron buttons can incline in the mould to be blocked, the frequency of the phenomenon is 3/1000 in actual production, and the anti-blocking device thoroughly eliminates the phenomenon.

2. The anti-blocking device does not need power, and the upper arm and the lower arm are in a force application state for the mesh bag under the action of the stretching of the spring in the process of folding the mesh bag; when the mesh bag is buckled and cut off, the left cantilever opens the front upper arm and the lower arm to push the mesh bag open preferentially, so that the mesh bag is separated faster, and the clamping stagnation phenomenon is thoroughly avoided.

3. The structure is added in a narrow space, the fault rate of 3/1000 in the production process is skillfully solved, the buckle mold is a 3/4 cone round hole, the iron buckle is a semi-cylinder, the net bag is similar to a soft cylinder, and when the folding mechanism is opened, the iron buckle is not easy to incline in the mold to be blocked, so that the packaging of the next bag is not affected. In actual production, this phenomenon occurs with a frequency of 3/1000.

Drawings

FIG. 1 is a diagram of the complete machine of an automatic mesh bag buckling packaging machine of the present utility model;

FIG. 2 is an installation perspective view of the automatic mesh bag buckling packaging machine of the present utility model;

FIG. 3 is a view showing the opened state of the buckling and cutting device of the automatic mesh bag buckling and packaging machine according to the present utility model;

FIG. 4 is a front view of the automatic mesh bag buckling packaging machine of the present utility model;

FIG. 5 is a schematic diagram of a sealing and cutting mechanism of an automatic mesh bag buckling and packaging machine according to the present utility model;

FIG. 6 is a cross-sectional view of the taper hole mechanism of the automatic mesh bag buckling packaging machine of the present utility model;

FIG. 7 is a front view of the anti-seize device of the automatic mesh bag buckling packaging machine of the present utility model;

FIG. 8 is a top view of the anti-seize device of the automatic mesh bag buckling packaging machine of the present utility model;

the marks in the figure: 1-a frame, 11-a supporting block and 12-a fixed shaft; 2-buckling and cutting devices, 21-folding mechanisms, 211-air cylinders, 212-air cylinder rods, 213-left cantilevers, 2131-upper plates, 2132-lower plates, 214-right auxiliary arms, 215-connecting rods, 216-right cantilevers, 217-folding plates, 218-limiting plates and 219-chain links; 22-sealing and cutting mechanisms, 221-oil cylinders, 222-oil cylinder rods, 223-upper driving rods, 224-lower driving rods, 225-wire binding devices, 226-taper hole mechanisms, 227-upper buckling molds, 228-lower buckling molds and 229-cutters; 23-left suspension shaft, 24-right suspension shaft and 25-crack; 3-anti-blocking device, 31-upper arm, 32-lower arm, 33-fixed column, 34-spring; 4-mesh bag.

Detailed Description

The technical scheme of the utility model is further described in non-limiting detail below with reference to the preferred embodiments and the accompanying drawings. In the description of the present utility model, it is to be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. refer to the azimuth or positional relationship based on the azimuth or positional relationship shown in the drawings. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present utility model, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise. The embodiments described below by referring to the drawings are illustrative and intended to explain the present utility model and should not be construed as limiting the utility model.

Referring to fig. 1-5, the utility model discloses a buckling mechanism with an anti-blocking device of an automatic mesh bag buckling packaging machine, which comprises a frame 1 and a buckling and cutting device 2 arranged on the frame 1, wherein the buckling and cutting device 2 comprises a gathering mechanism 21 and a sealing and cutting mechanism 22 which is matched with the gathering mechanism 21 for use; the folding mechanism 21 comprises an air cylinder 211, a left cantilever 213 and a right cantilever 216, the folding mechanism 21 is rotationally fixed through a supporting block 11 arranged on the frame 1, the left cantilever 213 is rotationally fixed on the supporting block 11 through a left cantilever shaft 23, and the right cantilever 216 is rotationally fixed on the supporting block 11 through a right cantilever shaft 24; the sealing and cutting mechanism 22 is arranged and fixed on the right cantilever 216, and the sealing and cutting mechanism 22 comprises a taper hole mechanism 226, an oil cylinder 221, an upper driving rod 223 and a lower driving rod 224; one end of the upper driving rod 223 and one end of the lower driving rod 224 are movably connected through an oil cylinder rod 222 arranged in the oil cylinder 221 to control a taper hole mechanism 226 to buckle and cut off the mesh bag 4; the tail part of the right cantilever 216 is movably connected through a cylinder rod 212 arranged in the cylinder 211, the tail part of the cylinder 211 is fixed on the frame 1 through a fixed shaft 12, the folding mechanism 21 further comprises a right auxiliary arm 214, one end of which is mutually and vertically fixed with the rear end part of the right cantilever 216, and the other end of the right auxiliary arm 214 is rotatably connected with the supporting block 11 through a right cantilever shaft 24; thereby increasing the rotation amplitude of the folding mechanism and facilitating the folding of the net bag into the buckling and cutting-off area; when the net bag is packed, the cylinder rod is contracted to enter the cylinder, the right cantilever is pulled to rotate around the right suspension shaft to enable the buckling and cutting device to be in an open state, when the net bag is buckled and cut off, the cylinder rod of the cylinder stretches out to push the right cantilever to rotate around the right suspension shaft to enable the buckling and cutting device to be in a closed state, and after the cylinder rod is driven by hydraulic oil to push the upper driving rod and the lower driving rod to rotate at the taper hole mechanism to buckle the net bag up and down, the middle of the net bag is cut off and separated.

As a further improvement of the buckling mechanism with the anti-jamming device of the automatic mesh bag buckling packaging machine, as shown in fig. 3, 7 and 8, the structure of the anti-jamming device is that a left cantilever 213 further comprises an upper plate 2131 and a lower plate 2132 matched with the upper plate 2131 for use, and the anti-jamming devices 3 are respectively arranged on the bottom edges of the upper plate 2131 and the lower plate 2132 and close to the mesh bag 4; the anti-seize device 3 comprises an upper arm 31, a lower arm 32 respectively arranged on the upper plate 2131 and the lower plate 2132 by a fixing post 33; the tail parts of the upper arm 31 and the lower arm 32 are elastically fixed through a spring 34, the front ends of the upper arm 31 and the lower arm 32 are preferentially contacted with the mesh bag when the upper arm 31 and the lower arm 32 rotate along with the left cantilever 213 to be close to the mesh bag, and the upper arm 31 and the lower arm 32 are in a force application state for the mesh bag under the action of the stretching of the spring in the process of folding the mesh bag; when the mesh bag is buckled and cut off, the left cantilever opens the front upper arm and the lower arm to push the mesh bag open preferentially, so that the mesh bag is separated faster, and the clamping stagnation phenomenon is thoroughly avoided.

As shown in fig. 3-6, as another embodiment of the present utility model: the taper hole mechanism 226 of the automatic mesh bag buckling packaging machine with the buckling mechanism of the anti-jamming device comprises an upper buckling die 227, a lower buckling die 228 and a cutter 229, wherein the cutter 229 is positioned between the upper buckling die 227 and the lower buckling die 228, iron wires are fed into the upper buckling die 227 and the lower buckling die 228 through a paying-off device 225 to buckle and tighten the mesh bag, and the cutter 229 cuts off the middle to separate the lower mesh bag, so that the upper mesh bag continues to package vegetables and fruits; a connecting rod 215 is arranged between the left cantilever 213 and the right auxiliary arm 214, when the right auxiliary arm 214 is pushed to rotate around the right cantilever shaft 24 by the expansion and contraction of the cylinder rod 212, the right auxiliary arm 214 drives the connecting rod 215 to push the left cantilever 213 to rotate around the left cantilever shaft 23 so as to realize the opening and closing of the folding mechanism 21, and in the folding process of the mesh bag, the mesh bag is close to the right cantilever stably, the skew is not easy to occur, and the buckling and cutting position is accurate.

In order to further improve the use effect of the present utility model, as shown in fig. 1 to 3, the cylinder rod 212 is disposed at the bottom of the rear end of the right cantilever 216 through a link 219, and the right cantilever 216 is further provided with a folding plate 217 and a limiting plate 218 cooperating with the folding plate 217, so as to prevent the mesh bag from swinging during folding; the folding plate 217 and the limiting plate 218 form a vertically-through gap 25 space for accommodating the mesh bag 4, and the taper hole mechanism 226 is positioned on the side wall of the gap 25 and is opposite to the left cantilever 213, so that the mesh bag can be conveniently pushed by the left cantilever to enter the taper hole mechanism after being folded.

When one bag is packed, iron wires bound at the upper end of the net bag form iron buttons which naturally fall off from the button forming mould along with the packing objects under the action of gravity, and iron buttons bound at the lower end of an unpacked empty bag of the next bag stay in the button forming mould, and when the folding mechanism is opened, the iron buttons are pulled out from the mould. The buckle mold is a 3/4 cone round hole, the iron buckle is a semi-cylinder, the net bag is similar to a soft cylinder, when the folding mechanism is opened, the iron buckle is not easy to incline in the mold to be blocked, and the packaging of the next bag is not affected. In practical production, the frequency of 3/1000 appears, and the anti-blocking device completely eliminates the phenomenon.

The automatic net bag buckling mechanism with the anti-blocking device comprises a folding mechanism, a sealing and cutting mechanism, a connecting rod and the like. Under the action of the folding cylinder, the two mechanisms rotate around the left suspension shaft and the left suspension shaft respectively in the directions shown in fig. 2 and 3. When the mechanism is in the closed state, the material enters the mesh bag from the mesh bag cylinder and stays on the upper plane of the mechanism, when the mechanism is opened, the mesh bag cylinder moves downwards to convey the mesh bag and the material to a proper position below the lower plane of the mechanism, and when the mesh bag cylinder is retracted to the original position, the mechanism is closed to shrink the mesh bag between the upper plane and the lower plane of the mechanism in a taper hole of the upper buckling mold and the lower buckling mold as shown in fig. 1. At this time, the seal cutting mechanism works, the net bag comprises two semicircular tying openings formed by iron wires with the cross section of 3 x 0.5, the net bag in the middle of the two tying openings is cut, and the series of actions are completed in about 0.2 seconds. It is conceivable that a bag of product packed under will fall off naturally under the force of gravity, thus completing a cycle of packing actions. However, since the buckling mold is a 3/4 taper hole mechanism, the iron buckle is a semi-cylinder, the net bag is similar to a soft cylinder, and when the folding mechanism is opened, the iron buckle can incline in the mold to be blocked, so that the packaging of the next bag is affected. In practical production, the phenomenon has the frequency of 3/1000, so that a set of mechanism device is additionally arranged at the narrow position of the folding mechanism shown in fig. 3, the device is a labor-consuming lever which can rotate, the lever is made of SUS304 steel plate which is fixed below the upper plate of the folding mechanism through a bearing due to space limitation, one labor-consuming end is tensioned by a small spring, after the net bag is cut off, tension is lost, the lever rapidly rebounds to eject the net bag under the action of the spring, and when the mechanism is opened again, the upper tying hole is pulled out of the buckling mould, so that the net bag buckling phenomenon is thoroughly eliminated. In actual production, the mechanism of the mechanism device is added without generating a phenomenon of no mechanism.

The foregoing examples illustrate only a few embodiments of the utility model and are described in detail herein without thereby limiting the scope of the utility model. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the utility model, which are all within the scope of the utility model. Accordingly, the scope of protection of the present utility model is to be determined by the appended claims.

Claims (10)

1. The utility model provides an automatic mesh bag is beaten and is buckled packagine machine's mechanism of beating that has anti-sticking device which characterized in that: the folding device comprises a frame (1) and a buckling and cutting device (2) arranged on the frame (1), wherein the buckling and cutting device (2) comprises a folding mechanism (21) and a sealing and cutting mechanism (22) which is matched with the folding mechanism (21) for use; the folding mechanism (21) comprises an air cylinder (211), a left cantilever (213) and a right cantilever (216), the folding mechanism (21) is rotationally fixed through a supporting block (11) arranged on the frame (1), the left cantilever (213) is rotationally fixed on the supporting block (11) through a left cantilever shaft (23), and the right cantilever (216) is rotationally fixed on the supporting block (11) through a right cantilever shaft (24); the sealing and cutting mechanism (22) is fixedly arranged on the right cantilever (216), and the sealing and cutting mechanism (22) comprises a taper hole mechanism (226), an oil cylinder (221), an upper driving rod (223) and a lower driving rod (224); one end of the upper driving rod (223) and one end of the lower driving rod (224) are movably connected through an oil cylinder rod (222) arranged in the oil cylinder (221) to control the taper hole mechanism (226) to buckle and cut off the mesh bag (4); the tail of the right cantilever (216) is movably connected through a cylinder rod (212) arranged in the cylinder (211), and the tail of the cylinder (211) is fixed on the frame (1) through a fixed shaft (12).

2. The automatic mesh bag buckling mechanism with anti-seize device of the automatic mesh bag buckling packaging machine as set forth in claim 1, wherein: the folding mechanism (21) further comprises a right auxiliary arm (214) with one end fixed with the rear end part of the right cantilever (216) in a mutually perpendicular mode, and the other end of the right auxiliary arm (214) is rotatably connected with the supporting block (11) through the right cantilever shaft (24).

3. The automatic mesh bag buckling mechanism with anti-seize device of the automatic mesh bag buckling packaging machine as set forth in claim 1, wherein: the cylinder rod (212) is arranged at the bottom of the rear end part of the right cantilever (216) through a chain ring (219), and the right cantilever (216) is also provided with a folding plate (217) and a limiting plate (218) matched with the folding plate (217).

4. A punching mechanism with an anti-seize device for an automatic mesh bag punching packaging machine as claimed in claim 3, characterized in that: a vertically-through crack (25) for accommodating the mesh bag (4) is formed between the folding plate (217) and the limiting plate (218), and the taper hole mechanism (226) is positioned on the side wall of the crack (25) and is opposite to the left cantilever (213).

5. The automatic mesh bag buckling mechanism with anti-seize device of the automatic mesh bag buckling packing machine according to claim 1 or 4, characterized in that: the taper hole mechanism (226) comprises an upper buckling die (227), a lower buckling die (228) and a cutter (229), wherein the cutter (229) is located between the upper buckling die (227) and the lower buckling die (228).

6. The automatic mesh bag buckling mechanism with anti-seize device of the automatic mesh bag buckling packaging machine as set forth in claim 1, wherein: a connecting rod (215) is arranged between the left cantilever (213) and the right auxiliary arm (214).

7. A punching mechanism with an anti-seize device for an automatic mesh bag punching packaging machine as claimed in claim 3, characterized in that: the expansion and contraction of the cylinder rod (212) pushes the right auxiliary arm (214) to rotate around the right suspension shaft (24), and the right auxiliary arm (214) drives the connecting rod (215) to push the left cantilever (213) to rotate around the left suspension shaft (23) so as to realize the opening and closing of the folding mechanism (21).

8. The automatic mesh bag buckling mechanism with anti-seize device of the automatic mesh bag buckling packaging machine as set forth in claim 7, wherein: the left cantilever (213) further comprises an upper plate (2131) and a lower plate (2132) which is matched with the upper plate (2131), and anti-blocking devices (3) are respectively arranged on one sides, close to the mesh bag (4), of the bottom edges of the upper plate (2131) and the lower plate (2132).

9. The automatic mesh bag buckling mechanism with anti-seize device of the automatic mesh bag buckling packaging machine as set forth in claim 8, wherein: the anti-seize device (3) comprises an upper arm (31) arranged on the upper plate (2131) and a lower arm (32) arranged on the lower plate (2132) through fixing posts (33).

10. The automatic mesh bag buckling mechanism with anti-seize device of the automatic mesh bag buckling packaging machine as set forth in claim 9, wherein: the tail parts of the upper arm (31) and the lower arm (32) are elastically fixed through a spring (34), and the front ends of the upper arm (31) and the lower arm (32) are preferentially contacted with the mesh bag (4) when the left cantilever (213) rotates to be close to the mesh bag.