Automatic packaging tape strapping equipment

Abstract

The utility model discloses an automatic packing tape strapping device which comprises a rack, a feeding and withdrawing mechanism, a tensioning mechanism, cutters and a driving mechanism, the cutters comprise an ironing cutter, a left cutter, a middle cutter, a sliding panel and a right cutter, a base is provided with a clamping seat, the left cutter and the right cutter are arranged below the lower wall of the clamping seat, and the left cutter and the right cutter are arranged on the lower wall of the clamping seat. The sliding panel is arranged below the clamping seat and located between the left cutter and the right cutter, the sliding panel is horizontally arranged in a sliding mode, the middle cutter is arranged below the sliding panel, and when the sliding panel is far away from the upper wall of the middle cutter, the ironing cutter is attached to the position close to the upper wall of the middle cutter. The main shaft is connected with a rotary driving device, and the main shaft is provided with an eccentric cam, a second eccentric cam, a third eccentric cam, a fourth eccentric cam, a fifth eccentric cam and a sixth eccentric cam which are arranged at intervals. According to the utility model, the structure is compact, and all the mechanisms realize sequential work of all the parts through the working time difference of the eccentric cams.

Description

Technical Field

[0001] The utility model relates to the field of strapping machines, in particular to an automatic strapping device for packaging straps. Background Art

[0002] The fully automatic strapping machine is a fully automatic strapping equipment. When working, you only need to move the packaging to the work surface to trigger the automatic switch on the table to automatically strap. The number of straps can be selected according to the packaging requirements. It can also be designed into various types such as power type or side-stamping type according to the user's production line to meet the requirements of different users.

[0003] When strapping items together, the existing strapping tape generally goes through the steps of wire threading, winding, pressing, ironing (or riveting) and shearing. Therefore, the pressing process of the strapping tape also includes processes such as pressing and tightening. Therefore, multiple tools are required to cooperate simultaneously. The existing tools are generally controlled by multiple drive devices during operation. The corresponding distances between the positions of the various tools are also large, so the overall size of the tool is large. Utility Model Content

[0004] The main purpose of the utility model is to provide an automatic packaging tape device, which aims to improve the spacing between each cutter of the tape machine, make the fit between the cutters more compact, and thus improve the fit of the cutters and processing efficiency.

[0005] To achieve the above-mentioned purpose, the present invention provides an automatic packaging tape strapping device, comprising:

[0006] A frame, wherein the frame is provided with a vertically arranged base;

[0007] A feeding and retracting mechanism, the feeding and retracting mechanism is used for conveying the belt body, and the feeding and retracting mechanism is arranged on the side wall of the frame;

[0008] A tensioning mechanism, wherein the tensioning mechanism is arranged adjacent to the feeding and retracting mechanism, and the belt body is transported toward the feeding and retracting mechanism after passing through the tensioning mechanism, and the tensioning mechanism is provided with a clamping wheel that cooperates with each other, and the clamping wheel is swingably mounted on the base;

[0009] The cutting tool comprises a hot cutting knife, a left cutting knife, a middle cutting knife, a sliding panel and a right cutting knife. The base is located above the sliding panel and is provided with a fixed holder. The left cutting knife and the right cutting knife are provided below the lower wall of the holder and are vertically slidable. The sliding panel is provided below the holder and between the left cutting knife and the right cutting knife. The sliding panel is provided horizontally.

[0010] The middle knife is arranged below the sliding panel. When the sliding panel is away from the upper wall position of the middle knife, the hot-sealing knife is attached to the upper wall position close to the middle knife.

[0011] a drive mechanism comprising a main shaft pivotally mounted on the frame, the main shaft being connected to the rotary drive device, the main shaft being provided with a first eccentric cam, a second eccentric cam, a third eccentric cam, a fourth eccentric cam, a fifth eccentric cam, and a sixth eccentric cam arranged at intervals;

[0012] The first eccentric cam is used to drive the ironing knife;

[0013] The second eccentric cam is used to drive the left knife;

[0014] The third eccentric cam is used to drive the middle knife;

[0015] The fourth eccentric cam is used to drive the sliding panel;

[0016] The fifth eccentric cam is used to drive the right knife;

[0017] The sixth eccentric cam is used to drive the clamping wheel.

[0018] The utility model has a compact structure, and each mechanism realizes the sequential operation of each part through the working time difference of the eccentric cam, effectively improving the production efficiency and enhancing the connectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a three-dimensional schematic diagram of the utility model;

[0020] Figure 2 Indicates the coordination of left and right knives Figure 1 ;

[0021] Figure 3 Indicates the coordination of left and right knives Figure 2 ;

[0022] Figure 4 It is a three-dimensional diagram of the right knife;

[0023] Figure 5 Indicates the hot knife Figure 1 ;

[0024] Figure 6 Indicates the hot knife Figure 2 ;

[0025] Figure 7 is a schematic diagram of a sliding panel;

[0026] Figure 8 This is a schematic diagram of being stabbed;

[0027] Figure 9 Schematic diagram of the tensioning mechanism Figure 1 ;

[0028] Figure 10 Schematic diagram of the tensioning mechanism Figure 2 ;

[0029] Figure 11 It is a transverse cross-sectional view of the middle knife part;

[0030] Figure 12 A simplified diagram of the coordination between the strapping tape and each tool;

[0031] Figure 13 A locally enlarged schematic diagram.

[0032] In the figure,

[0033] 1 is the frame, 11 is the base, 12 is the card seat,

[0034] 2 is the sending and retracting mechanism, 20 is the sending and retracting wheel, 21 is the sending and retracting rotating motor, 22 is the guide channel, 23 is the sending and retracting channel,

[0035] 3 is a tensioning mechanism, 30 is a clamping wheel, 31 is a first driving arm, 32 is a second driving arm, 33 is a tensioning rotary motor, 34 is a tensioning wheel,

[0036] 4 is a hot-sealing knife, 41 is a triangular driving plate, and 42 is a first tension spring;

[0037] 5 is the left knife, 50 is the first guide post, 51 is the second tension spring,

[0038] 6 is the middle knife, 60 is the I-shaped seat,

[0039] 7 is a sliding panel, 71 is a horizontal guide rod, 72 is a guide groove, 73 is a swing arm,

[0040] 8 is the right knife, 80 is the second guide post, 81 is the fifth tension spring, 82 is the through hole, 83 is the first tooth part, 84 is the first tooth groove, 85 is the cutting knife,

[0041] 9 is a rotation drive device, 90 is a main shaft, 91 is a first eccentric cam, 92 is a second eccentric cam, 93 is a third eccentric cam, 94 is a fourth eccentric cam, 95 is a fifth eccentric cam, 96 is a sixth eccentric cam,

[0042] 101 is the first driving wheel, 102 is the second driving wheel, 103 is the third driving wheel, 104 is the fourth driving wheel, 105 is the fifth driving wheel, 106 is the sixth driving wheel,

[0043] 200 is the belt body, 201 is the head end, and 202 is the tail end. DETAILED DESCRIPTION

[0044] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0045] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, top, bottom, inside, outside, vertical, horizontal, longitudinal, counterclockwise, clockwise, circumferential, radial, axial...), then the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0046] In addition, if there are descriptions involving "first" or "second" in the embodiments of the present invention, the descriptions of "first" or "second" are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features specified as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0047] like Figures 1 to 13 As shown, an automatic packaging tape strapping device includes:

[0048] A frame 1, wherein the frame 1 is provided with a vertically arranged base 11;

[0049] A feeding and retracting mechanism 2, which is used to convey the belt and is provided on a side wall of the frame 1;

[0050] A tensioning mechanism 3 is provided adjacent to the feeding and retracting mechanism 2, and the belt body is transported toward the feeding and retracting mechanism 2 after passing through the tensioning mechanism 3. The tensioning mechanism 3 is provided with a clamping wheel 30 that cooperates with each other, and the clamping wheel 30 is swingably mounted on the base 11;

[0051] The cutting tool comprises a hot pressing knife 4, a left knife 5, a middle knife 6, a sliding panel 7 and a right knife 8. The base 11 is located above the sliding panel 7 and is provided with a fixed holder 12. The left knife 5 and the right knife 8 are provided below the lower wall of the holder 12 and are vertically slidable. The sliding panel 7 is provided below the holder 12 and between the left knife 5 and the right knife 8. The sliding panel 7 is provided horizontally.

[0052] The middle knife 6 is arranged below the sliding panel 7. When the sliding panel 7 is away from the upper wall position of the middle knife 6, the ironing knife 4 is attached to the upper wall position close to the middle knife 6.

[0053] A drive mechanism, the drive mechanism comprising a main shaft 90 pivotally mounted on the frame 1, the main shaft 90 being connected to the rotary drive device 9, the main shaft 90 being provided with a first eccentric cam 91, a second eccentric cam 92, a third eccentric cam 93, a fourth eccentric cam 94, a fifth eccentric cam 95, and a sixth eccentric cam 96 arranged at intervals;

[0054] The first eccentric cam is used to drive the ironing knife 4;

[0055] The second eccentric cam is used to drive the left knife 5;

[0056] The third eccentric cam is used to drive the middle knife 6;

[0057] The fourth eccentric cam is used to drive the sliding panel 7;

[0058] The fifth eccentric cam is used to drive the right knife 8;

[0059] The sixth eccentric cam is used to drive the clamping wheel 30 .

[0060] The utility model has a compact structure, and each mechanism realizes the sequential operation of each part through the working time difference of the eccentric cam, effectively improving the production efficiency and enhancing the connectivity.

[0061] Specifically, the base 11 is vertically provided with a first guide column 50 and a second guide column 80 spaced apart. The left knife 5 is slidably mounted on the first guide column 50 , and the right knife 8 is slidably mounted on the second guide column 80 .

[0062] The rear ends of the left knife 5 and the right knife 8 are provided with a second driving wheel 102 and a fifth driving wheel 105 respectively;

[0063] The second driving wheel 102 cooperates with the second eccentric cam to drive the left knife 5 to move vertically, and can switch between the processing position and the standby position;

[0064] The fifth driving wheel 105 cooperates with the fifth eccentric cam to drive the right knife 8 to move vertically, and can be switched between the processing position and the standby position.

[0065] In the actual design, through the cooperation of the second eccentric cam and the fifth eccentric cam, the same main shaft 90 can control the left knife 5 and the right knife 8 respectively, and the sliding operation of the left knife 5 and the right knife 8 is stable.

[0066] In the embodiment of the present utility model, a second tension spring 51 is provided between the base 11 and the left knife 5, and a fifth tension spring 81 is provided between the base 11 and the right knife 8. The second tension spring 51 is used to drive the left knife 5 to return to the standby position, and the fifth tension spring 81 is used to drive the right knife 8 to return to the standby position.

[0067] The left knife 5 and the right knife 8 are both bent in structure, thereby achieving the resetting of the left knife 5 and the right knife 8.

[0068] Specifically, the right knife 8 is provided with a through hole 82, and the upper end of the right knife 8 is provided with a first pressing portion, and the first pressing portion is provided with a first tooth portion 83, and the first tooth portion 83 can abut against the lower wall of the clamping seat 12, and the clamping seat 12 is provided with a first tooth groove 84 that cooperates with the first pressing seat (pressing together, thereby removing pressure from the tail end and the head end, ensuring stable ironing);

[0069] The right blade 8 is provided with a cutting blade 85 at a position facing the side wall of the middle blade 6. The cutting blade 85 is arranged at an angle. In specific operation, the belt body of the feeding and retracting mechanism 2 first passes through the through hole 82, then passes through the sliding panel 7 in sequence, and then passes through the right blade 8 to wrap the article, and then extends into the space between the first tooth portion 83 and the clamping seat 12. The belt can be manually or automatically tied by a corresponding belt guide mechanism.

[0070] The cutting blade 85 is used to separate the closed-loop strapping tape from the strap body. The cutting blade is tilted to make the strap body cutting smoother and reduce the problem of burrs.

[0071] In the embodiment of the present utility model, the lower end of the ironing knife 4 is pivotally mounted on the base 11, and a triangular driving plate 41 is provided between the ironing knife 4 and the upper wall of the base 11. The front end of the triangular driving plate 41 is pivotally connected to the middle part of the ironing knife 4, the lower end of the triangular driving plate 41 is pivotally connected to the base 11, and the rear end of the triangular driving plate 41 is pivotally connected to the knife seat of the right knife 8.

[0072] A first driving wheel 101 is provided at the rear end of the triangular driving plate 41 away from the knife seat of the right knife 8;

[0073] A first tension spring 42 is provided between the base 11 and the middle portion of the ironing knife 4 to move the ironing knife 4 to the standby position.

[0074] In the actual design, the ironing knife 4 and the right knife 8 are used in conjunction with each other. When the right knife 8 and the lower wall of the card seat 12 are against each other, one end of the belt body is locked. When the tail end and the beginning of the belt body are stacked and fall into the upper wall of the middle knife 6, the first eccentric cam cooperates with the first driving wheel 101, thereby driving the ironing knife 4 and the upper wall of the middle knife 6 to fit together, thereby realizing the automatic closed loop (fixation) of the strapping tape.

[0075] Specifically, a horizontal guide rod 71 is provided between the card holder 12 and the base 11, and the sliding panel 7 is slidably mounted on the horizontal guide rod 71. A guide groove 72 is provided through the front wall of the sliding panel 7, and the guide groove 72 is inclined upward from right to left.

[0076] The frame 1 is provided with a swing arm 73, the middle part of the swing arm 73 is pivotally connected to the frame 1, the lower end of the swing arm 73 is provided with a fourth driving wheel 104, the fourth driving wheel 104 cooperates with the fourth eccentric cam, and the upper end of the swing arm 73 is pivotally connected to the rear end of the sliding panel 7.

[0077] When the fourth driving wheel 104 cooperates with the fourth eccentric cam, it drives the sliding panel 7 to move to the standby position (so that the front end and the tail end stacked parts of the belt body move to the upper wall position of the middle knife 6). The sliding panel 7 can have a built-in spring to keep it in the processing position at all times. Of course, it can also be replaced and set according to the simplicity of the structure.

[0078] In an embodiment of the present utility model, the middle knife 6 is arranged on an I-shaped seat 60, and the I-shaped seat 60 is slidably installed on the first guide column and the second guide column. The rear end of the I-shaped seat 60 is provided with a third driving wheel 103 that cooperates with the third eccentric cam.

[0079] The third driving wheel 103 drives the middle knife 6 upward, and a spring is provided between the I-shaped seat 60 and the frame 1 to reset the I-shaped seat 60 (to keep the I-shaped seat 60 in the standby position).

[0080] Specifically, the base 11 is laterally provided with a first driving arm 31, and the clamping wheel 30 is pivotally mounted on the inner wall of the driving arm.

[0081] The tensioning mechanism 3 includes a tensioning rotary motor 33 and a tensioning wheel 34 connected to the tensioning rotary motor 33.

[0082] The frame 1 is longitudinally mounted with a second driving arm 32. The middle portion of the second driving arm 32 is pivotally connected to the frame 1. The rear end of the second driving arm 32 is provided with a sixth driving wheel 106 that cooperates with the sixth eccentric cam.

[0083] The front end is connected to the first driving arm 31,

[0084] When the sixth eccentric cam abuts against the sixth driving wheel 106 , the first driving arm 31 drives the second driving arm 32 to swing, and drives the tensioning wheel 34 to abut against the clamping wheel 30 .

[0085] The tensioning rotary motor 33 drives the belt body to retreat and tightens the head end of the strapping belt, thereby tightening the goods.

[0086] In an embodiment of the present utility model, the feed-and-return mechanism 2 includes a feed-and-return wheel 20 provided on the front side wall of the base 11 and a feed-and-return rotary motor 21 provided on the other side of the base 11. The feed-and-return rotary motor 21 can drive the feed-and-return wheel 20 to rotate. The front end of the feed-and-return wheel 20 is provided with a guide belt seat, and the guide belt seat is provided with a guide belt channel 22. The rear end of the feed-and-return wheel 20 is provided with a limit seat, and the limit seat and the feed-and-return wheel 20 form a feed-and-return channel 23.

[0087] When the feeding and retracting rotary motor 21 drives the feeding and retracting wheel 20 to rotate, the belt body is transported forward, thereby advancing the belt body. When the belt body needs to be tightened, the feeding and retracting rotary motor 21 and the tensioning wheel 34 move in the opposite direction, thereby tightening the belt body.

[0088] The control steps include:

[0089] S1: The end of the package body extends between the tension wheel 34 and the clamping wheel 30, and then passes through the feeding and retracting channel 23, the feeding and retracting wheel 20 and the belt guide channel 22;

[0090] S2: The end of the belt body extends into the through hole 82 of the right knife 8 and the guide groove 72 of the sliding panel 7, then passes through the left knife 5 and extends out of the frame 1 to wrap the goods;

[0091] S3: When the leading end of the belt passes through the right knife 8 and the holder 12 and extends to a predetermined length and overlaps with the trailing end of the belt;

[0092] S4: At this time, the fifth eccentric cam is used to drive the right knife 8 upward and engage with the base 11, so that the head is fixed, that is, the length of the head end is sufficient, and the belt body is tightened as needed;

[0093] S5: The sixth eccentric cam drives the clamping wheel 30 to abut against the tensioning wheel 34. At this time, the tensioning motor and the retracting rotary motor 21 move in the opposite direction, tightening the belt body in the belt groove to a predetermined tension value.

[0094] S6: The second eccentric cam drives the left knife 5 upward and clamps it with the clamping seat 12, so that the head end and the tail end are stacked and in a relatively relaxed state;

[0095] S7: The fourth eccentric cam drives the sliding plate 7 to move away from the middle blade 6, so that the stacked portion is placed on the upper wall of the middle blade 6;

[0096] S8: The first eccentric cam drives the ironing knife 4 and the third eccentric cam drives the middle knife 6 to move closer together, thereby ironing and fixing the laminated parts.

[0097] Its structure is simple and stable, and its overall volume is smaller. Compared with conventional strapping machines, it reduces at least 3 rotating motors, effectively saving the overall equipment cost, and the technical design has structural coordination.

[0098] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention specification and drawings under the practical concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. An automatic strapping device for packaging tape, characterized in that: include: A frame, wherein the frame is provided with a vertically arranged base; A feeding and retracting mechanism, the feeding and retracting mechanism is used for conveying the belt body, and the feeding and retracting mechanism is arranged on the side wall of the frame; A tensioning mechanism, wherein the tensioning mechanism is arranged adjacent to the feeding and retracting mechanism, and the belt body is transported toward the feeding and retracting mechanism after passing through the tensioning mechanism, and the tensioning mechanism is provided with a clamping wheel that cooperates with each other, and the clamping wheel is swingably mounted on the base; The knife comprises a hot pressing knife, a left knife, a middle knife, a sliding panel and a right knife. The base is located above the sliding panel and is provided with a fixed holder. The left knife and the right knife are arranged below the lower wall of the holder and are vertically slidable. The sliding panel is arranged below the holder and between the left knife and the right knife. The sliding panel is arranged horizontally. The middle knife is arranged below the sliding panel. When the sliding panel is away from the upper wall position of the middle knife, the hot-sealing knife is attached to the upper wall position close to the middle knife. A driving mechanism, the driving mechanism comprising a main shaft pivotally mounted on the frame, the main shaft being connected to the rotary driving device, the main shaft being provided with a first eccentric cam, a second eccentric cam, a third eccentric cam, a fourth eccentric cam, a fifth eccentric cam and a sixth eccentric cam arranged at intervals; The first eccentric cam is used to drive the ironing knife; The second eccentric cam is used to drive the left knife; The third eccentric cam is used to drive the middle knife; The fourth eccentric cam is used to drive the sliding panel; The fifth eccentric cam is used to drive the right knife; The sixth eccentric cam is used for driving the clamping wheel.

2. The automatic strapping device for packaging straps according to claim 1, characterized in that: The base is vertically provided with a first guide column and a second guide column spaced apart from each other, the left knife is slidably mounted on the first guide column, and the right knife is slidably mounted on the second guide column. The rear ends of the left knife and the right knife are respectively provided with a second driving wheel and a fifth driving wheel; The second driving wheel cooperates with the second eccentric cam to drive the left knife to move vertically, and can be switched between the processing position and the standby position; The fifth driving wheel and the fifth eccentric cam cooperate with each other to drive the right knife to move vertically, and can be switched between the processing position and the standby position.

3. The automatic strapping device for packaging straps according to claim 2, characterized in that: A second tension spring is provided between the base and the left knife, and a fifth tension spring is provided between the base and the right knife, wherein the second tension spring is used to drive the left knife to return to the standby position, and the fifth tension spring is used to drive the right knife to return to the standby position; The left knife and the right knife are both in a bent structure.

4. The automatic strapping device for packaging straps according to claim 2, characterized in that: The right knife is provided with a through hole, the upper end of the right knife is provided with a first pressing part, the first pressing part is provided with a first tooth part, the first tooth part can be against the lower wall of the clamping seat, and the clamping seat is provided with a first tooth groove matched with the first pressing seat; A cutting knife is arranged at a position of the right knife facing the side wall of the middle knife, and the cutting knife is arranged obliquely.

5. The automatic strapping device for packaging straps according to claim 1, characterized in that: The lower end of the ironing knife is pivotally mounted on the base, a triangular driving plate is provided between the ironing knife and the upper wall of the base, the front end of the triangular driving plate is pivotally connected to the middle part of the ironing knife, the lower end of the triangular driving plate is pivotally connected to the base, and the rear end of the triangular driving plate is pivotally connected to the knife seat of the right knife. A first driving wheel is provided at a position of the rear end of the triangular driving plate away from the knife seat of the right knife; A first tension spring is provided in the middle of the base and the ironing knife to move the ironing knife to the standby position.

6. The automatic strapping device for packaging straps according to claim 1, characterized in that: A horizontal guide rod is arranged horizontally between the card seat and the base, the sliding panel is slidably mounted on the horizontal guide rod, a guide groove is arranged through the front wall of the sliding panel, and the guide groove is arranged upwardly from right to left. The frame is provided with a swing arm, the middle part of the swing arm is pivotally connected to the frame, the lower end of the swing arm is provided with a fourth driving wheel, the fourth driving wheel cooperates with the fourth eccentric cam, and the upper end of the swing arm is pivotally connected to the rear end of the sliding panel.

7. The automatic strapping device for packaging straps according to claim 2, characterized in that: The middle knife is arranged on an I-shaped seat, and the I-shaped seat is slidably mounted on a first guide column and a second guide column. A third driving wheel matching with a third eccentric cam is arranged at the rear end of the I-shaped seat.

8. The automatic strapping device for packaging tape according to claim 2, characterized in that: The base is laterally provided with a first driving arm, and the clamping wheel is pivotally mounted on the inner wall of the driving arm. The tensioning mechanism includes a tensioning rotary motor and a tensioning wheel connected to the tensioning rotary motor. The frame is longitudinally mounted with a second driving arm, the middle portion of which is pivotally connected to the frame, and the rear end of which is provided with a sixth driving wheel matched with a sixth eccentric cam. The front end is connected to the first driving arm, When the sixth eccentric cam abuts against the sixth driving wheel, the first driving arm drives the second driving arm to swing and drives the tensioning wheel to abut against the clamping wheel.

9. The automatic strapping device for packaging tape according to claim 2, characterized in that: The delivery and retraction mechanism includes a delivery and retraction wheel arranged on the front side wall of the base and a delivery and retraction rotating motor arranged on the other side of the base. The delivery and retraction rotating motor can drive the delivery and retraction wheel to rotate. A belt guide seat is provided at the front end of the delivery and retraction wheel, and a belt guide seat is provided at the belt guide channel. A limit seat is provided at the rear end of the delivery and retraction wheel, and the limit seat and the delivery and retraction wheel form a delivery and retraction channel.

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