CN113665179B

CN113665179B - Cutting mechanism for plastic packaging bag production

Info

Publication number: CN113665179B
Application number: CN202110983236.1A
Authority: CN
Inventors: 崔清磊; 王满意
Original assignee: Henan Zhongsu New Material Co ltd
Current assignee: Henan Zhongsu New Material Co ltd
Priority date: 2021-08-25
Filing date: 2021-08-25
Publication date: 2023-05-23
Anticipated expiration: 2041-08-25
Also published as: CN113665179A

Abstract

The invention discloses a cutting mechanism for plastic packaging bag production, which comprises a feeding mechanism, a cutting mechanism and a discharging mechanism which are sequentially arranged, wherein a feeding roller capable of pushing materials to feed is arranged in the feeding mechanism; a movable material guide channel capable of reciprocating along the material feeding direction is arranged in the cutting mechanism, a hot melt knife and a cutting knife capable of extruding towards the middle surface are arranged in the movable material guide channel, the hot melt knife and the cutting knife can synchronously or asynchronously start extrusion, and the extrusion force of the hot melt knife and the extrusion force of the cutting knife can be the same or different; the utility model provides a plastic packaging bag production is with cutting mechanism increase unloading mechanism, can force the breaking away from with preceding bag through dragging to preceding bag, and unloading mechanism increases the swinging arms that can open and shut, the feeding direction of bag after the guide, the overlap ratio of finished product when guaranteeing to pile up realizes putting things in good order effect.

Description

Cutting mechanism for plastic packaging bag production

Technical Field

The invention relates to the technical field of packaging bag production equipment, in particular to a cutting mechanism for plastic packaging bag production.

Background

In the production process of plastic packaging bags, the packaging bags need to be stacked after being cut, and the stacking is guaranteed to be neat, so that the follow-up packing operation is facilitated, the phenomenon that the cutting is incomplete exists when the existing plastic bags are cut, namely, the front bags and the rear bags are adhered, the front bags are affected by the rear bags when being stacked, the front bags cannot be tidily aligned with the original contrast, the stacking of finished products is not facilitated, and the plastic bags are quite easy to deform when external force is received, so that the front bags and the rear bags are completely separated from each other at the cutting position, the rear bags are difficult to continuously advance according to the route of the front bags when continuously fed, the continuous guiding is needed to be carried out on the rear bags in the reproduction process of the plastic bags, and the overlapping rate of the plastic bags in the stacking process is guaranteed, so that the effect of orderly stacking is achieved.

Disclosure of Invention

The invention aims to overcome the existing defects, and provides a cutting mechanism for plastic packaging bag production, which is additionally provided with a discharging mechanism, can force the front bag to be separated by dragging the front bag, is additionally provided with an openable swing plate, guides the feeding direction of the rear bag, ensures the overlapping rate of finished products during stacking, realizes the effect of orderly stacking, and can effectively solve the problems in the background art.

In order to achieve the above purpose, the present invention provides the following technical solutions: the cutting mechanism for plastic packaging bag production comprises a feeding mechanism, a cutting mechanism and a discharging mechanism which are sequentially arranged, wherein a feeding roller capable of pushing materials to feed is arranged in the feeding mechanism;

a movable material guide channel capable of reciprocating along the material feeding direction is arranged in the cutting mechanism, a hot melt knife and a cutting knife capable of extruding towards the middle surface are arranged in the movable material guide channel, the hot melt knife and the cutting knife can synchronously or asynchronously start extrusion, and the extrusion force of the hot melt knife and the extrusion force of the cutting knife can be the same or different;

the discharging mechanism comprises two groups of oscillating plates with adjustable included angles, discharging rollers for driving materials to feed are arranged in the oscillating plates, and when the included angles of the two groups of oscillating plates are at the minimum value, the discharging rollers in the oscillating plates are in a opposite rolling state;

when the hot melt knife and the cutting knife synchronously work, the hot melt knife positioned at the downstream of the cutting knife can be separated earlier than the cutting knife.

As a preferable technical scheme of the invention, the circumferential line speed of the discharging roller is greater than that of the feeding roller;

when the front bag is contacted with the discharging mechanism, the discharging roller inside drives the front bag to feed, the feeding roller drives the rear bag to feed, the front bag and the rear bag are both driving rollers, rolling friction is formed between the front bag and the plastic bag and the front bag and the rear bag are both rolling bodies of the plastic bag, sliding friction does not exist, when the linear speeds of the front bag and the rear bag are inconsistent, a pulling force is generated between the front bag and the rear bag along the feeding direction, and therefore the front bag and the rear bag can be disconnected at a cutting line.

As a preferable technical scheme of the invention, the discharging mechanism can move obliquely upwards along the arc-shaped track, the bottom of the arc-shaped track is tangential to the feeding direction of the materials, and when the discharging mechanism moves upwards along the arc-shaped track, the included angle between the two inner groups of swinging plates is at the minimum value;

the discharging mechanism further comprises an arc-shaped guide rail which is fixedly arranged, a sliding frame is arranged in the arc-shaped guide rail in a sliding mode, one ends of the two groups of swinging plates are rotatably arranged with the sliding frame, gear pairs with the transmission ratio of 1 are arranged at the rotating shafts of the two groups of swinging plates, a stepping motor for driving and rotating is arranged at the rotating shaft of one group of swinging plates, and meanwhile, the discharging mechanism further comprises a telescopic rod for driving the sliding frame to slide along the arc-shaped guide rail;

in the falling process of the discharging mechanism, the included angle of the swinging plates is increased, the lower end of the arc-shaped guide rail is tangent to the feeding direction of the materials, the materials from the movable material guide channel enter the area between the two groups of swinging plates conveniently, then, the angle of the swinging plates is reduced, the discharging roller clamps the materials, the front bag and the rear bag are pulled apart from the cutting line along with the upward movement of the discharging mechanism, the front bag is lifted to a certain height, and after the discharging roller moves to a designated position under the action of the discharging roller, the front bag is thrown down, the plastic bag is ensured to have high overlapping with the front plastic bag, so that the stacking is tidy, and a conveying belt with intermittent motion can be matched at the throwing position, so that the transfer after the quantitative stacking is realized.

As a preferable technical scheme of the invention, the cutting knife comprises a strip knife and a C-shaped bent knife, the strip knife and the bent knife enclose a closed trapezoid space, the length of the long side of the trapezoid space is shorter than that of the strip knife, a push plate which can be pressed down along with the cutting knife is arranged in the trapezoid space, and in the process of combining and extruding the cutting knife, the push plate can be pressed down through the middle surface of the movable material guide channel;

for the plastic bag with the portable parts, the top part of the plastic bag also needs a hot-melt stitching part, and the area between the two groups of portable parts needs to be cut off, but most of waste materials in the prior art cannot be separated from the finished product, or are adhered to the finished product; therefore, a pushing plate capable of being pressed down to pass through the middle surface is added, and an acting force perpendicular to the surface of the material is applied to push the cutting area to separate from the material.

As a preferable technical scheme of the invention, the hot-melt knife comprises a first hot-melt knife and a second hot-melt knife, wherein the first hot-melt knife is positioned at the downstream side of the long-strip knife, the second hot-melt knife is positioned at the upstream side of the long-strip knife, and the second hot-melt knife is in two sections and is respectively positioned at two sides of a trapezoid space;

according to the orientation of the packaging bag in the production process, the cutting area can be placed on the upstream side or the downstream side of the strip cutter, the upstream side is taken as an example, the second hot melting cutter is designed into two sections and placed on two sides of the cutting area, and the portable parts at the top of the packaging bag are subjected to hot melting bonding.

As a preferable technical scheme of the invention, the upper side and the lower side of the movable material guide channel are respectively provided with a tool rest capable of sliding vertically, racks which are arranged vertically are arranged in the tool rest, the racks of the upper and the lower sets of tool rests are meshed with a set of gears at the same time and are positioned at the two sides of the gears, and the hot melt knife, the cutting knife and the pushing plate are respectively connected with the tool rest at the corresponding side through elastic pieces which are arranged vertically;

the inside of the cutting mechanism is provided with a stepping motor for driving the gear to rotate, and when the gear rotates, the stepping motor is meshed with racks on two sides simultaneously to drive knife rests on two sides to synchronously move, so that extrusion and separation of an internal hot melt knife and the cutting knife are realized, and extruded contact points are always positioned on the middle surface of a movable material guide channel, so that the integral feeding direction of materials is not influenced.

As a preferable technical scheme of the invention, the lengths of the elastic parts of the first hot melt knife, the cutting knife, the second hot melt knife and the push plate, which are connected with the knife rest, are L1, L2, L3 and L4 respectively, wherein L1 is more than L2 and less than or equal to L3 or L1 = L3 and less than L2, and L4 is less than L2;

the elastic coefficients of the elastic pieces connected with the knife rest of the first hot melt knife, the cutting knife and the second hot melt knife are respectively K1, K2 and K3, wherein K1 is equal to L1=K3 is equal to or less than L3 is equal to or less than K2 is equal to L2;

through the length restriction to different elastic components, when realizing the knife rest motion, the extrusion and the separation order of different hot melt sword and cutting knife, simultaneously to the restriction of elasticity coefficient, realize that different hot melt sword and cutting knife possess the ability of different extrusion forces when the complete extrusion.

As a preferable technical scheme of the invention, the upper and lower wall surfaces of the material guide channel for the material to pass through are respectively provided with an air guide groove, the length direction of the air guide groove is consistent with the feeding direction of the material, and the air guide grooves are communicated with an external air source through air guide pipes;

through the air guide groove in the inside of the guide channel, which is provided with the feeding length direction, and is communicated with an external air source, an air film can be formed between the inner wall of the guide channel and the material, static electricity generated by friction between the plastic bag and the inner wall of the guide channel is avoided, and adhesion is avoided.

Compared with the prior art, the invention has the beneficial effects that: the cutting mechanism for plastic packaging bag production limits the separation sequence after combining the hot melt knife and the cutting knife which work synchronously, and designs the downstream side line speed of the cutting knife to be larger than the upstream side line speed of the cutting knife, so that the front bag and the rear bag can be pulled and separated at the cutting knife position, and the problem that the front bag and the rear bag still have adhesion after cutting is avoided; in addition, the cutting mechanism can do reciprocating motion, and when cutting is carried out, the cutting mechanism can synchronously feed along with materials, namely, continuous combination of the hot melt knife and the cutting knife is realized, the combination time is ensured, and the combination effect is ensured; meanwhile, the angle of the swinging plate in the unloading mechanism is adjustable, namely, the size of the opening at the initial end of a channel for feeding materials is adjustable, and when the front bag and the rear bag are separated and the rear bag enters the unloading mechanism again, the material guide channel of the unloading mechanism cannot be introduced due to lack of guiding.

Drawings

FIG. 1 is a schematic diagram of the structure of the present invention;

FIG. 2 is a cross-sectional view of the present invention;

FIG. 3 is a schematic diagram showing the combination of a hot melt knife and a cutting knife according to the present invention;

FIG. 4 is a schematic view of a cutting blade according to the present invention;

FIG. 5 is a schematic diagram of the structure of an air guide groove in the material guide channel of the present invention;

FIG. 6 is a simplified diagram of the positional relationship of various components in an embodiment of the present invention;

FIG. 7 is a simplified diagram of the positional relationship of various components in another embodiment of the present invention;

the solid arrows in fig. 6 and 7 point in the material feed direction, and the open arrows point in the direction of movement of the discharge mechanism;

fig. 8 is a schematic view of the hot melt and cut positions of the log.

In the figure: 1. a raw material; 101. a front bag bottom seam; 102. cutting lines; 103. a rear bag head seam; 104. cutting out the area; 2. a feeding mechanism; 201. fixing a material guide channel; 202. a feed roller; 3. a cutting mechanism; 301. a movable material guiding channel; 302. a tool holder; 303. a first motor; 304. a second motor; 305. a rack; 306. a first hot melt knife; 307. a cutting knife; 308. a second hot melt knife; 309. a push plate; 4. a discharging mechanism; 401. a swinging plate; 402. an arc-shaped guide rail; 403. a carriage; 404. a telescopic rod; 405. and a discharging roller.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Referring to fig. 8, when cutting the raw material 1, the front bag bottom seam 101 and the rear bag head seam 103 need to be hot-melted and summed, the position of the cutting line 102 needs to be cut, and the surrounding area in the cutting line 102 is a cutting area 104, so that the internal surplus material needs to be removed.

Referring to fig. 1-2, the present invention provides a technical solution: the cutting mechanism for plastic packaging bag production comprises a feeding mechanism 2, a cutting mechanism 3 and a discharging mechanism 4 which are sequentially arranged, wherein a feeding roller 202 capable of pushing materials to feed is arranged in the feeding mechanism 2;

a movable material guide channel 301 capable of reciprocating along the material feeding direction is arranged in the cutting mechanism 3, a hot melt knife and a cutting knife 307 capable of extruding towards the middle surface are arranged in the movable material guide channel 301, the hot melt knife and the cutting knife 307 can synchronously or asynchronously start extrusion, and the extrusion force of the hot melt knife and the extrusion force of the cutting knife 307 can be the same or different;

the cutting mechanism 3 both sides are provided with the guide rail of absolute fixed, and cutting mechanism 3 and guide rail slidable mounting, the trend of guide rail is unanimous with the direction of feed of raw materials 1, is provided with straight rack along the direction of motion in the cutting mechanism 3, and the fixed first motor 303 that is provided with in one side of guide rail, first motor 303 tip be provided with straight rack engaged gear, first motor 303 is through forward rotation and upset, drive cutting mechanism 3 along guide rail forward or reverse feed, realize reciprocating motion.

The discharging mechanism 4 comprises two groups of swinging plates 401 with adjustable included angles, discharging rollers 405 for driving materials to feed are arranged in the swinging plates 401, and when the included angles of the two groups of swinging plates 401 are at the minimum value, the discharging rollers 405 in the two groups of swinging plates are in a opposite rolling state;

when the hot-melt knife is operated in synchronization with the cutting knife 307, the hot-melt knife downstream of the cutting knife 307 can be disengaged earlier than the cutting knife 307.

The feeding mechanism 2 further includes a fixed material guiding channel 201 for passing a material, the height of the fixed material guiding channel 201 is identical to that of the movable material guiding channel 301, and the feeding rollers 202 are opposite roller bodies and are distributed on the upper side and the lower side of the fixed material guiding channel 201.

The peripheral line speed of the discharge roller 405 is greater than that of the feed roller 202;

when the front bag is contacted with the unloading mechanism 4, the front bag is driven by the inner unloading roller 405, the rear bag is driven by the feeding roller 202, the front bag and the rear bag are driven by the driving roller, rolling friction is formed between the front bag and the plastic bag, the front bag and the rear bag are both rolling bodies, sliding friction does not exist, when the linear speeds of the front bag and the rear bag are inconsistent, a pulling force is generated between the front bag and the rear bag along the feeding direction, and therefore the front bag and the rear bag can be disconnected at the cutting line 102.

The discharging mechanism 4 can move obliquely upwards along the arc-shaped track, the bottom of the arc-shaped track is tangential to the feeding direction of the materials, and when the discharging mechanism 4 moves upwards along the arc-shaped track, the included angle between the two inner swinging plates 401 is at the minimum value;

the unloading mechanism 4 further comprises an arc-shaped guide rail 402 which is fixedly arranged, a sliding frame 403 is arranged in the arc-shaped guide rail 402 in a sliding mode, one ends of the two groups of swinging plates 401 are rotatably arranged with the sliding frame 403, gear pairs with the transmission ratio of 1 are arranged at the rotating shafts of the two groups of swinging plates 401, a stepping motor for driving and rotating is arranged at the rotating shaft of one group of swinging plates 401, and meanwhile, the unloading mechanism 4 further comprises a telescopic rod 404 for driving the sliding frame 403 to slide along the arc-shaped guide rail 402;

in the falling process of the discharging mechanism 4, the included angle of the swinging plates 401 is increased, the lower end of the arc-shaped guide rail 402 is tangent to the feeding direction of materials, the materials from the movable material guide channel 301 conveniently enter the area between the two groups of swinging plates 401, then, the angles of the swinging plates 401 are reduced, the discharging rollers 405 clamp the materials, the front bag and the rear bag are pulled apart from the cutting line 102 along with the upward movement of the discharging mechanism 4, the front bag is lifted to a certain height, and after the front bag moves to a designated position under the action of the discharging rollers 405, the front bag is thrown down, the front bag is guaranteed to have high overlapping with the plastic bag thrown down before, so that the stacking is tidy, and a conveying belt with intermittent motion can be matched at the throwing position, so that the transfer after the quantitative stacking is realized.

Referring to fig. 3-4, the cutting knife 307 includes a long knife and a C-shaped curved knife, the long knife and the curved knife enclose a closed trapezoid space, the long side of the trapezoid space is shorter than the length of the long knife, a pushing plate 309 capable of being pressed down along with the cutting knife 307 is arranged in the trapezoid space, and in the process of combining and pressing the cutting knife 307, the pushing plate 309 can be pressed down to pass through the middle surface of the movable material guide channel 301;

for the plastic bag with the portable parts, the top part of the plastic bag also needs a hot-melt stitching part, and the area between the two groups of portable parts needs to be cut off, but most of waste materials in the prior art cannot be separated from the finished product, or are adhered to the finished product; thus increasing the push plate 309 that can be pushed down over the mid-plane, exerting a force perpendicular to the surface of the material, pushing the cut-out 104 away from the material.

The hot melt knife comprises a first hot melt knife 306 and a second hot melt knife 308, wherein the first hot melt knife 306 is positioned on the downstream side of the long strip knife, the second hot melt knife 308 is positioned on the upstream side of the long strip knife, and the second hot melt knife 308 is two-section and is positioned on two sides of the trapezoid space;

depending on the orientation of the package during production, the cutting area 104 may be disposed on the upstream side or downstream side of the slitter, where the upstream side is taken as an example, and the second hot-melt knife 308 is designed to be two-stage and disposed on both sides of the cutting area 104 to thermally fuse the top, portable portions of the package.

The upper side and the lower side of the movable material guide channel 301 are respectively provided with a tool rest 302 capable of sliding vertically, a rack 305 arranged vertically is arranged in the tool rest 302, the racks 305 of the upper and the lower sets of tool rests 302 are simultaneously meshed with a set of gears and are positioned on two sides of the gears, and a hot melt knife, a cutting knife 307 and a push plate 309 are respectively connected with the tool rests 302 on the corresponding sides through elastic pieces arranged vertically;

the step motor with a driving gear for rotation is arranged in the cutting mechanism 3, the step motor is a second motor 304 and is relatively fixed with the cutting mechanism 3, when the first and second motors 304 drive the gears to rotate, the first and second motors are simultaneously meshed with racks 305 on two sides to drive knife holders 302 on two sides to synchronously move, extrusion and separation of an internal hot-melt knife and a cutting knife 307 are realized, and extruded contact points are always positioned on the middle surface of a movable material guide channel 301, so that the integral feeding direction of materials is not influenced.

Referring to fig. 6-7, the lengths of the elastic members of the first hot melt knife 306, the cutting knife 307, the second hot melt knife 308 and the push plate 309 connected to the knife holder 302 are L1, L2, L3, L4, L1 < L2 +.l 3 or l1=l3 < L2, and L4 < L2, respectively;

the elastic coefficients of the elastic members of the first hot melt knife 306, the cutting knife 307 and the second hot melt knife 308 connected with the knife rest 302 are respectively K1, K2 and K3, wherein k1=k3×l3 is less than or equal to k2×l2;

by limiting the length of different elastic pieces, extrusion and separation sequences of different hot melt knives and cutting knives 307 are realized when the knife rest 302 moves, and meanwhile, limitation of elastic coefficients is realized, so that the capability of different extrusion forces of different hot melt knives and cutting knives 307 is realized when the knife rest is completely extruded.

In fig. 6 and 7, the light dotted line portion is the material guiding channel of the unloading mechanism 4, which is convenient for the raw material 1 from upstream to enter the unloading mechanism 4 when the unloading mechanism 4 is at the lowest end and the included angle of the swinging plate 401 is at the maximum; the light solid line part is the state when the discharging mechanism 4 is at the highest position, and the finished products after being cut at the moment are rapidly discharged under the action of the discharging roller 405 and are accepted by the follow-up accepting mechanism, so that the high overlapping degree of the finished products is ensured each time when the finished products are accepted, and the orderly stacking is ensured.

Referring to fig. 6, L1 < L2 < L3, L4 < L2, k1×l1=k3×l3.ltoreq.k2×l2, during operation, the second hot-melt knife 308, the cutting knife 307, and the first hot-melt knife 306 are combined and pressed in sequence, and during detachment, the first hot-melt knife 306 is detached first, at this time, the discharging mechanism 4 drives the front bag and the rear bag to separate, at this time, since the cutting knife 307 is not detached, there is a fixing effect on the rear bag, when the front bag and the rear bag are separated, a relatively regular separation line can be formed at the cutting line 102, after the front bag and the rear bag are completely separated, the cutting knife 307 and the second hot-melt knife 308 are detached in sequence, and before the cutting knife 307 is detached, the push plate 309 can be pressed down to remove the residual materials in the cutting area 104, and likewise, the cutting line 102 is relatively regular due to the fixing effect of the cutting knife 307.

Referring to fig. 7, l1=l3 < L2, L4 < L2, k1=l1=k3×l3.ltoreq.k2×l2, at this time, the first and second hot-

melt blades

306 and 308 are synchronously combined and separated, and have the same hot-melt time, and the hot-melt effects are consistent.

Referring to fig. 5, the upper and lower wall surfaces of the material guide channel for the material to pass through inside the feeding mechanism 2, the cutting mechanism 3 and the discharging mechanism 4 are respectively provided with an air guide groove, the length direction of the air guide grooves is consistent with the feeding direction of the material, and the air guide grooves are communicated with an external air source through air guide pipes;

When in use: the upstream continuous raw material 1 enters the feeding mechanism 2 through the fixed material guiding channel 201, is fed under the action of the feeding roller 202, then enters the movable material guiding channel 301, the hot melt knife and the cutting knife 307 in the cutting mechanism 3 are synchronously pressed down and combined, in the combining process, the cutting mechanism 3 synchronously feeds along with the raw material 1, after the first hot melt knife 306 is separated, the cutting knife 307 is separated, the discharging mechanism 4 drives the front bag to discharge and separate from the rear bag, then the cutting knife 307 and the hot melt knife are completely separated, the cutting mechanism 3 is quickly reset, the next circulation flow is carried out, the swinging plate 401 of the discharging mechanism 4 drives the finished product to be moved to a high position to discharge, then the reset is carried out to receive a new finished product, and the previous flow is continued.

Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. The utility model provides a plastic packaging bag production is with cutting mechanism, includes feeding mechanism (2), cutting mechanism (3) and shedding mechanism (4) that arrange in proper order, its characterized in that: a feeding roller (202) capable of pushing materials to feed is arranged in the feeding mechanism (2);

a movable material guide channel (301) capable of reciprocating along the material feeding direction is arranged in the cutting mechanism (3), a hot melt knife and a cutting knife (307) capable of extruding towards the middle surface are arranged in the movable material guide channel (301), the hot melt knife and the cutting knife (307) can synchronously or asynchronously start extrusion, and extrusion forces of the hot melt knife and the cutting knife (307) can be the same or different;

the discharging mechanism (4) comprises two groups of swinging plates (401) with adjustable included angles, discharging rollers (405) for driving materials to feed are arranged in the swinging plates (401), and when the included angles of the two groups of swinging plates (401) are at the minimum value, the discharging rollers (405) in the two groups of swinging plates are in a opposite rolling state;

when the hot melt knife and the cutting knife (307) synchronously work, the hot melt knife positioned at the downstream of the cutting knife (307) can be separated from the packaging bag to be processed earlier than the cutting knife (307);

the circumferential line speed of the discharging roller (405) is greater than that of the feeding roller (202);

the cutting knife (307) comprises a strip knife and a C-shaped bent knife, the strip knife and the bent knife enclose a closed trapezoid space, the length of the long side of the trapezoid space is shorter than that of the strip knife, a pushing plate (309) capable of being pressed down along with the cutting knife (307) is arranged in the trapezoid space, and in the process of combining and extruding the cutting knife (307), the pushing plate (309) can be pressed down to pass through the middle surface of the movable material guide channel (301);

the hot melt knife comprises a first hot melt knife (306) and a second hot melt knife (308), wherein the first hot melt knife (306) is positioned on the downstream side of the long strip knife, the second hot melt knife (308) is positioned on the upstream side of the long strip knife, and the second hot melt knife (308) is in two sections and is respectively positioned on two sides of a trapezoid space;

the upper side and the lower side of the movable material guide channel (301) are respectively provided with a tool rest (302) capable of sliding vertically, racks (305) which are arranged vertically are arranged in the tool rest (302), the racks (305) of the upper tool rest and the lower tool rest (302) are simultaneously meshed with a group of gears and are positioned on the two sides of the gears, and the hot melt knife, the cutting knife (307) and the pushing plate (309) are respectively connected with the tool rest (302) on the corresponding side through elastic pieces which are arranged vertically;

the lengths of elastic pieces connected with the knife rest (302) of the first hot melt knife (306), the cutting knife (307), the second hot melt knife (308) and the push plate (309) are respectively L1, L2, L3 and L4, L1 is more than L2 and less than or equal to L3 or L1=L3 is less than L2, and L4 is less than L2;

elastic coefficients of elastic pieces, connected with the knife rest (302), of the first hot melt knife (306), the cutting knife (307) and the second hot melt knife (308) are respectively K1, K2 and K3, and K1=K3=L3=L3 is less than or equal to K2×L2.

2. The cutting mechanism for plastic packaging bag production according to claim 1, wherein: the discharging mechanism (4) can move obliquely upwards along the arc-shaped track, the bottom of the arc-shaped track is tangential to the feeding direction of the materials, and when the discharging mechanism (4) moves upwards along the arc-shaped track, the included angle between the two inner groups of swinging plates (401) is at the minimum value;

the discharging mechanism (4) further comprises an arc-shaped guide rail (402) which is fixedly arranged, a sliding frame (403) is slidably arranged in the arc-shaped guide rail (402), one ends of the two groups of swinging plates (401) are rotatably arranged on the sliding frame (403), a gear pair with a transmission ratio of 1 is arranged at the rotating shaft of the two groups of swinging plates (401), a stepping motor which drives to rotate is arranged at the rotating shaft of one group of swinging plates (401), and meanwhile, the discharging mechanism (4) further comprises a telescopic rod (404) which drives the sliding frame (403) to slide along the arc-shaped guide rail (402).

3. The cutting mechanism for plastic packaging bag production according to claim 1 or 2, characterized in that: the feeding mechanism (2), the cutting mechanism (3) and the discharging mechanism (4) are respectively provided with an air guide groove on the surfaces of the upper wall and the lower wall of a material guide channel for materials to pass through, the length direction of the air guide grooves is consistent with the feeding direction of the materials, and the air guide grooves are communicated with an external air source through air guide pipes.