Telescopic and foldable lower die mechanism and patch pocket machine

Abstract

The invention relates to a lower die mechanism capable of being telescopically folded and a pocket patching machine. The lower die mechanism capable of being telescopically folded comprises a base; the lower mold plate is of a split deformation structure, has an unfolded working state and a relatively narrowed state and comprises a plurality of unit plates, and the unit plates are movably matched with each other relative to the base; and the driving mechanism is mounted on the base, is linked with each unit plate and is used for driving the lower template to switch the state. According to the lower die mechanism, the split deformable lower die plate is adopted, the width can be adaptively changed according to different machining stages, the lower die plate can be pulled out from bag-shaped cloth with a narrowed opening, all unit plates are movably arranged, the movement stroke is more reasonable, and the narrowing range adaptability is higher.

Description

TECHNICAL FIELD

[0001] The present application relates to the sewing equipment technical field, especially to a foldable and retractable lower die mechanism and a bag attaching machine. BACKGROUND

[0002] The bag attaching machine is mainly applied to the sewing of pockets, and flat sewing and overlock can be completed at one time, and is suitable for the sewing of back pockets of various jeans, pockets of shirts, and other irregular parts in garment processing.

[0003] In the working process of the bag attaching machine, the bag-shaped cloth is laid on the lower die plate, and then the upper die mechanism in the folding edge mechanism cooperates with the lower die plate. The upper die mechanism is provided with an electromagnet, which can attract the lower die plate to clamp the bag-shaped cloth. The folding knife in the folding edge mechanism is inserted into the lower part of the two sides of the bag-shaped cloth to complete the folding edge operation of the bag-shaped cloth.

[0004] When the folding edge mechanism is reset, the lower die plate needs to be pulled out from the lower part of the bag-shaped cloth. When the lower part of the pocket is wider than the upper part, the lower die plate is blocked at the folding edge part and cannot be pulled out due to the small opening of the upper part after being inserted and completing the folding edge operation.

[0005] In addition, with the improvement of the quality requirements of garments, it is required that the edge of the pocket be free of burrs. The existing process is to manually fold the two sides (near the pocket part) of the bag-shaped cloth inward for the first time, then fold the upper part of the bag-shaped cloth inward for the second time, and then sew the upper part of the bag-shaped cloth. Therefore, the upper folding edge of the pocket is free of burrs. However, when the other parts of the bag-shaped cloth away from the pocket part are folded by the bag attaching machine, the lower die plate cannot be smoothly pulled out due to the combined action of the upper folding edge and the side folding edge. Therefore, the existing technology generally adopts manual sewing for the sewing of the pockets with the lower part wider than the upper part and the inner pocket edge free of burrs, which leads to low efficiency and high labor cost. SUMMARY

[0006] The present application provides a lower die mechanism for a bag attaching machine, which can be applied to the bag-shaped cloth with the lower part wider than the upper part and the inner pocket edge free of burrs, and can further improve the production efficiency.

[0007] The present application provides a foldable and retractable lower die mechanism, which comprises:

[0008] a base;

[0009] a lower die plate adopting a split deformation structure and having an unfolded working state and an opposite narrow state, the lower die plate comprising a plurality of unit plates, and each unit plate being movably matched with the base;

[0010] a driving mechanism installed on the base and linked with each unit plate, for driving the lower die plate to switch states.

[0011] The following also provides several optional modes, but not as an additional limitation of the above general scheme, just a further supplement or preferred, without technical or logical contradiction, each optional mode can be combined alone for the above general scheme, but also can be combined between multiple optional modes.

[0012] In one embodiment, the unit plate comprises:

[0013] The middle plate moves along the first direction;

[0014] The side plate comprises a left plate and a right plate arranged on both sides of the middle plate along the second direction, and the left plate and the right plate move along the second direction;

[0015] The base has opposite front and rear sides, the first direction extends along the front and rear direction, and the second direction is perpendicular to the first direction.

[0016] In one embodiment, each unit plate is independently configured with the driving mechanism;

[0017] Or each unit plate shares the same set of driving mechanisms, and the left plate and the right plate move synchronously and reversely.

[0018] In one embodiment, the base and the side plate are in contact with the elastic member, so that the lower die plate tends to be in a narrow state or a working state.

[0019] In one embodiment, in the working state, the front side edges of each unit plate are connected to each other;

[0020] In the narrow state, the middle plate is further close to the base along the first direction, and the left plate and the right plate are close to each other to surround the front side of the middle plate.

[0021] In one embodiment, the left plate and the right plate are respectively provided with a clearance on the side facing each other, and in the narrow state, the front side of the middle plate is located in the clearance.

[0022] In one embodiment, the driving mechanism comprises:

[0023] The cylinder is mounted on the base, and the middle plate is connected to the piston rod of the cylinder;

[0024] The connecting rod is two, one end of each connecting rod is hinged to the piston rod of the cylinder, and the other end is hinged to each side plate.

[0025] In one embodiment, the piston rod of the cylinder is provided with a stroke adjusting member, and the stroke adjusting member acts on the cylinder body to limit the retraction limit position of the piston rod.

[0026] In one embodiment, all the unit plates are arranged in a plane.

[0027] The left plate and the right plate are respectively provided with a avoiding slot on the side opposite to the other side, for the edge of the bag-shaped cloth to be folded and placed in.

[0028] The application also provides a bag pasting machine, comprising an upper die mechanism and a lower die mechanism cooperating to clamp the bag-shaped cloth to implement the edge folding, wherein the lower die mechanism is the retractable and foldable lower die mechanism as described above.

[0029] The upper die mechanism is provided with a plurality of sets of force applying assemblies, each set of force applying assemblies acting on a corresponding unit plate, and each set of force applying assemblies comprising a suction member for keeping the unit plate clamped with the upper die mechanism to clamp the bag-shaped cloth, and a pushing member for driving the unit plate to be separated from the upper die mechanism.

[0030] The lower die mechanism of the application adopts a split deformable lower die plate, which can adaptively change the width according to different processing stages, and is extracted from the bag-shaped cloth with a narrowed mouth, and each unit plate is movably arranged, so that the movement stroke is more reasonable and the narrowing range is more adaptive. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0032] Figure 1 FIG. 1 is a structural schematic diagram of the lower die mechanism in one embodiment of the application;

[0033] Figure 2 FIG. 2 is a structural schematic diagram of the lower die mechanism in FIG. 1 without the top frame; Figure 1

[0034] Figure 3 FIG. 3 is a sectional view along A-A in FIG. 2; Figure 1

[0035] Figure 4 FIG. 4 is an enlarged view of a part in FIG. 3; Figure 3

[0036] Figure 5 FIG. 5 is a schematic diagram of the lower die plate cooperating with the bag-shaped cloth with a narrow upper part and a wide lower part;

[0037] Figure 6 FIG. 6 is a schematic diagram of the lower die plate in FIG. 5 being extracted from the bag-shaped cloth; Figure 5

[0038] Figure 7 FIG. 7 is a schematic diagram of the lower die plate in FIG. 5 being extracted from the bag-shaped cloth;​​​​Figure 1 Structure diagram of the middle and lower die mechanism in the narrowing state;

[0039] Figure 8 For Figure 1 Structure diagram of the middle and lower die mechanism cooperating with the upper die mechanism;

[0040] Figure 9 For Figure 8 Partial diagram of the middle and lower die mechanism from the bottom angle;

[0041] Figure 10 For Figure 8 Structure diagram of the middle and upper die mechanism.

[0042] The element reference numbers are as follows:

[0043] 100, base;

[0044] 110, bottom plate; 111, limiting piece;

[0045] 120, top frame; 121, middle plate guide seat; 122, stop block; 123, limiting shaft; 124, elastic piece; 125, side plate guide rail;

[0046] 200, lower die plate; 201, middle plate; 202, left plate; 203, right plate; 204, avoiding groove; 205, avoiding area;

[0047] 210, middle plate connecting seat; 211, middle plate guide rail;

[0048] 220, left plate connecting seat; 221, left plate guide seat; 222, clamping groove; 223, strip-shaped hole;

[0049] 230, right plate connecting seat; 231, right plate guide seat;

[0050] 240, transition plate; 241, clamping block;

[0051] 300, driving mechanism; 310, air cylinder; 311, cylinder body; 312, piston rod; 313, joint; 314, stroke adjusting piece; 320, connecting rod;

[0052] 400, upper die mechanism; 410, fixed seat; 420, upper concave die; 430, suction piece; 440, pushing piece;

[0053] 500, bag-shaped cloth; 501, side folding edge; 502, bag opening folding edge. DETAILED DESCRIPTION

[0054] In order to make the above objectives, features and advantages of the present application more clear and comprehensible, the detailed description of the specific embodiments of the present application is made below with reference to the accompanying drawings. In the following description, a lot of specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be implemented in many different ways other than the one described herein, and one of ordinary skill in the art can make similar improvements without departing from the scope of the present application, and therefore the present application is not limited to the specific embodiments disclosed below.

[0055] It is to be noted that when a component is referred to as being "on" or "disposed on" another component, it can be directly on the other component or there can be intervening components present. When a component is referred to as being "connected" to another component, it can be directly connected to the other component or there can be intervening components present. The terms "vertical", "horizontal", "upper", "lower", "left", "right", and similar terms as used in the description of the specification are for the purpose of illustration only and do not indicate an exclusive embodiment.

[0056] In addition, the terms "first", "second", and the like, are used merely to describe the features and do not imply or suggest relative importance or a number of the features indicated. Thus, the features defined with "first", "second" can include at least one of the features explicitly or implicitly. In the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise explicitly specified and limited.

[0057] In the present application, unless otherwise explicitly specified and limited, the "on", "under", "above" and "over" of a first feature to a second feature can be that the first feature is in direct contact with the second feature, or the first feature is indirectly in contact with the second feature through an intermediate medium. Moreover, the "on", "above" and "over" of a first feature to a second feature can be that the first feature is directly above or obliquely above the second feature, or only indicates that the first feature is higher than the second feature in horizontal height (or in a use state, or in a certain drawing perspective). The "under", "below" and "under" of a first feature to a second feature can be that the first feature is directly below or obliquely below the second feature, or only indicates that the first feature is lower than the second feature in horizontal height (or in a use state, or in a certain drawing perspective).

[0058] Unless otherwise defined, all technical and scientific terms used in the specification of the present application have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used in the specification of the present application are only for the purpose of describing the specific embodiments and are not intended to limit the present application. The term "and / or" used in the specification of the present application includes any and all combinations of one or more of the related listed items.

[0059] Reference is made to Figures 1 to 4An embodiment of the present application provides a scalable and foldable lower mold mechanism, which comprises a base 100 for mounting other components and an external power mechanism. When applied to a bagging machine, the base 100 can be lifted and / or horizontally moved under the drive of the power mechanism. The base 100 has opposite front and rear sides, Figure 1 In the embodiment, the first direction X extends in the front-rear direction, and the second direction Y is perpendicular to the first direction Y and is also a horizontal direction.

[0060] The lower mold plate 200 is located on the front side of the base 100 as a whole. In the embodiment, the lower mold plate 200 adopts a split deformation structure, i.e., comprises a plurality of unit plates. Each unit plate is movably connected to the base. The relative movement of the plurality of unit plates can change the width (the size in the second direction) of the lower mold plate 200, so as to facilitate the separation of the bag opening part of the bag-shaped fabric. The shape and number of the unit plates are not strictly limited, for example, 2-6 pieces. The lower mold plate 200 has an unfolded working state and an opposite narrow state. In the working state, the lower mold plate 200 supports the inner edge of the folded edge part of the bag-shaped fabric. When the folded edge needs to be separated from the lower mold plate 200, in order to avoid being blocked by the narrowed bag opening or the stopper part, the relative movement of the plurality of unit plates narrows the width of the lower mold plate 200. The driving mechanism 300 is installed on the base 100 and is linked with each unit plate, and is used to drive the lower mold plate 200 to switch states.

[0061] In the embodiment, all the unit plates are movably connected to the base 100, for example, sliding or rotating connection. The state can be switched through a relatively short stroke, so that the structure of the lower mold mechanism is more compact as a whole. Moreover, the space arrangement of each unit plate in the narrow state is more reasonable.

[0062] Taking three unit plates as an example, in one embodiment, the unit plate comprises:

[0063] a middle plate 201 movably connected to the base 100 in the first direction;

[0064] side plates, including a left plate 202 and a right plate 203 arranged on both sides of the middle plate 201 in the second direction. The left plate 202 and the right plate 203 are movably connected to the base 100 in the second direction. Here, “left” and “right” are only for easy description and are relative concepts. Either side can be the left side, and the other side is the right side.

[0065] The left plate 202 and the right plate 203 can have a movement component in the second direction relative to the base 100. In a preferred embodiment, the left plate 202 and the right plate 203 only move in the second direction relative to the base, i.e., without movement components in other directions. The relative movement in other directions is more efficient when switching to the narrow state. The lower mold mechanism as a whole can have a smaller size in the first direction, which is more conducive to optimizing the space arrangement of the equipment.

[0066] Each unit board can be configured with an independent drive mechanism or all unit boards can share the same drive mechanism. Through linkage control or setting a synchronization mechanism, the left plate 202 and the right plate 203 can achieve synchronous reverse movement. When switching to the narrowing state, they have the same movement stroke relative to the middle plate 201.

[0067] The middle plate 201 moves along the first direction, further coordinating with the movement of the left plate 202 and the right plate 203, allowing the three to be staggered along the first direction in the narrowed state. Especially in the preferred embodiment, the thickness of each unit plate is no more than 1.5mm, and all unit plates are arranged coplanarly. The unit plates avoid mutual interference through their shape matching, achieving overall width change under the premise of coplanarity. The coplanar arrangement of all unit plates does not require them to have the same thickness, which can be understood as not overlapping each other, thus avoiding mutual interference when switching states. In addition, after the bag-shaped fabric is folded, it may push the left plate 202 and the right plate 203 higher. Therefore, the middle plate 201 can be slightly thicker (e.g., 0.5mm thicker) than the left plate 202 and the right plate 203 to compensate for this height difference.

[0068] In one embodiment, the base 100 includes a bottom plate 110 and a top frame 120. Each unit plate has a connecting seat on its rear side to cooperate with the drive mechanism 300. For example, a middle plate connecting seat 210 is fixed to the rear side of the middle plate 201, and a middle plate guide rail 211 is fixed on the middle plate connecting seat 210. A middle plate guide seat 121 that slides with the middle plate guide rail 211 is fixed to the bottom side of the top frame 120 to guide the middle plate 201 to move in a first direction.

[0069] A transition plate 240 is fixed to the rear side of the left plate 202, and a left plate connecting seat 220 is detachably connected to the transition plate 240. A left plate guide seat 221 is fixed on the left plate connecting seat 220. A side plate guide rail 125 that slides with the left plate guide seat 221 is fixed to the bottom side of the top frame 120 to guide the left plate 202 to move in the second direction.

[0070] Similarly, a corresponding transition plate is fixed to the rear side of the right plate 203, and the right plate connecting seat 230 is detachably connected through the transition plate. The right plate connecting seat 230 is fixed with a right plate guide seat 231, and the bottom side of the top frame 120 is fixed with a side plate guide rail that slides with the right plate guide seat 231 to guide the right plate 203 to move in the second direction.

[0071] The positions of the guide rails and guide seats in the above embodiments can be interchanged, and the specific structure is not strictly limited, at least achieving sliding fit and mutual anti-detachment. For more stable movement, two sets of mutually cooperating guide rails and guide seats can be set for the same side plate. In some embodiments, the guide rails and guide seats corresponding to the left plate 202 and the right plate 203 can also be extended integrally.

[0072] In one embodiment, taking the cooperation between the transition plate 240 and the left plate connecting seat 220 as an example (the same applies to the right side), the left plate connecting seat 220 has a slot 222, and the transition plate 240 has a locking block 241 that cooperates with the slot 222 for positional alignment when they are connected. The transition plate 240 and the connecting seat can be quickly disassembled, improving ease of operation and assembly efficiency.

[0073] For each connector, two or more sets of corresponding slots 222 and blocks 241 can be provided, and each block 241 can be further fixed to the connector in a way that facilitates disassembly.

[0074] For ease of adjustment, the left plate connecting seat 220 is provided with a strip-shaped hole 223, and is fixed to the transition plate 240 by a fastener passing through the strip-shaped hole 223. The fastener can be adjusted along the strip-shaped hole 223, that is, the distance between the left plate 202 and the left plate connecting seat 220 in the second direction is adjustable, and is tightened and locked after adjustment. This facilitates further alignment of the relative positions of each unit plate along the second direction during assembly.

[0075] Adjustable structures can be provided between each unit plate and its corresponding connecting seat, as well as between each connecting seat and the base 100, to adjust the position of each unit plate along the height direction and ensure that each unit plate is arranged on the same plane.

[0076] In one embodiment, all unit boards share the same drive mechanism 300, which includes a cylinder 310 and a connecting rod 320.

[0077] The cylinder 310 includes a cylinder body 311 mounted on the base 100 and a piston rod 312 slidably fitted to the cylinder body 311. The middle plate connecting seat 210 is connected to the piston rod 312 of the cylinder 310.

[0078] There are two connecting rods 320. One end of each connecting rod 320 is hinged to the piston rod 312 of the cylinder 310, and the other end is hinged to the left plate connecting seat 220 or the right plate connecting seat 230.

[0079] When the piston rod 312 moves, it directly links the middle plate 201 to move in the first direction, and also causes each side plate to move in the second direction through the reversing of the connecting rod 320.

[0080] In one embodiment, in order to accurately determine the extreme position of the middle plate 201 moving forward, the front side of the bottom plate 110 is provided with a limiting member 111, such as a threaded push rod. When the middle plate 201 moves forward to the extreme position, the middle plate connecting seat 210 or the middle plate guide rail 211 abuts against the limiting member 111.

[0081] In one embodiment, in order to determine the lateral position of each side plate in the narrowed state, the piston rod 312 is provided with a stroke adjustment member 314. The position of the stroke adjustment member 314 is adjustable and fixed to the piston rod 312. When the piston rod 312 moves to the extreme position in the rearward direction, the stroke adjustment member 314 abuts against the cylinder 311 to limit the retraction limit position of the piston rod 312.

[0082] In one embodiment, see Figure 3 , Figure 4 An elastic element 124 acts between the base 100 and the side plate, causing the lower template 200 to tend towards a narrowing state or a working state, thereby providing a unidirectional preload. In this embodiment, taking the tendency towards the narrowing state as an example (the lower template 200 is in the working state, and the elastic element 124 stores and releases energy), it can ensure that the lower template 200 can quickly narrow when it retracts and detaches from the bag-shaped fabric, in order to overcome the resistance to movement reversal, and can also further eliminate the positional error caused by the guide rail gap.

[0083] The specific installation method of the elastic element 124 is as follows: a stop 122 is fixed on the side of the top frame 120, and the left plate connecting seat 220 (the same applies to the right side) is provided with a mounting hole. The stop 122 is fixed with a limiting shaft 123 that extends into the mounting hole. The elastic element 124 can be a spiral compression spring sleeved on the limiting shaft 123. Both ends press against the stop 122 and the left plate connecting seat 220 respectively to help the lower template 200 narrow. Correspondingly, when the lower template 200 is in working state, the left plate connecting seat 220 compresses the elastic element 124, and the elastic element 124 accumulates and releases energy accordingly.

[0084] To meet the requirement of no rough edges at the stop, see Figure 2 In one embodiment, the left plate 202 and the right plate 203 are respectively provided with clearance grooves 204 on opposite sides. The clearance grooves 204 roughly correspond to the bag opening. During operation, the two sides of the bag-shaped fabric 500 (near the bag opening) are first folded inward to obtain the side folds 501. Then, the upper opening of the bag-shaped fabric 500 is folded inward to obtain the bag opening fold 502. After the upper opening of the bag-shaped fabric 500 is sewn, it is fitted onto the lower template 200. The clearance grooves 204 correspond precisely to and avoid the stop area. Then, in cooperation with the upper mold mechanism, the front part of the bag-shaped fabric 500 is folded. After folding, the lower template 200 switches to a narrowed state and disengages from the bag-shaped fabric 500.

[0085] Combination Figure 5 , Figure 6 , Figure 7In the working state, the front edges of the middle plate 201, left plate 202 and right plate 203 of the lower template 200 are connected to form a continuous extended outer contour, which corresponds to the narrowed bag-shaped fabric 500. A large gap is left between the left plate 202 and the right plate 203 to provide narrowing space. After the folding is completed, the lower template 200 cannot be directly pulled out because the bag opening of the bag-shaped fabric 500 is narrow. Each unit plate of this application can move relative to each other to adapt to the switching of the lower template 200 to the narrowing state. The piston rod 312 moves backward and directly links the middle plate connecting seat 210 through the joint 313 to make the middle plate 201 move closer to the base 100 in the first direction. Both connecting rods 320 are rotated and engaged with the joint 313. Under the drive of the connecting rods 320, the left plate connecting seat 220 and the right plate connecting seat 230 move closer to each other in the second direction, so that the left plate 202 and the right plate 203 move closer to each other and surround the front side of the middle plate 201.

[0086] The front side of the middle plate 201 is T-shaped. In the working state, the horizontal part of the T-shape is connected to the front side of the left plate 202 and the right plate 203. The left plate 202 and the right plate 203 are respectively provided with a clearance area 205 on the opposite side. In the narrowed state, the horizontal part of the T-shape moves relative to the left plate 202 and the right plate 203 in the first direction and is located in the clearance area 205, allowing the left plate 202 and the right plate 203 to move towards each other. Overall, the lower template 200 is narrowed to detach from the bag-shaped fabric 500.

[0087] See Figures 8 to 10 In one embodiment of this application, a bag-applying machine is also provided, including an upper mold mechanism 400 and a lower mold mechanism that cooperate with each other to clamp bag-shaped fabric for folding. The lower mold mechanism can be combined with the embodiments described above, and will not be described again here.

[0088] The upper mold mechanism 400 includes a fixed base 410 and an upper die 420 mounted on the fixed base 410. The upper die 420 is connected to the fixed base 410 and moves with the fixed base 410. The upper die 420 has a mold cavity for inserting bag-shaped fabric and the lower template 200. The mold cavity is located on the side of the upper die 420 facing away from the fixed base 410.

[0089] The upper mold mechanism 400 is equipped with multiple sets of force-applying components. Each set of force-applying components acts on a corresponding unit plate. Specifically, there are three sets that can act on the middle plate 201, left plate 202, and right plate 203 respectively. Each set of force-applying components includes a suction member 430 that acts on the unit plate to keep each unit plate in contact with the upper mold mechanism 400 and clamp the bag-shaped fabric, and a pusher member 440 that drives the unit plate to detach from the upper mold mechanism 400. The suction force of the suction member 430 drives the lower mold plate 200 into the mold cavity, and correspondingly, the pusher member 440 pushes the lower mold plate 200 out of the mold cavity. The suction member 430 can be an electromagnet that attracts the corresponding unit plate, and the pusher member 440 can be a cylinder that pushes the corresponding unit plate to help it detach from the upper die 420.

[0090] In this embodiment, the suction member 430 ensures the upper mold mechanism 400 and the lower template are closely fitted during the folding process to guarantee fitting accuracy, while the pusher member 440 enables rapid separation of the upper mold mechanism 400 and the lower template during the reset process. This ensures both the fitting accuracy of the upper mold mechanism 400 and the lower template and facilitates easy separation, achieving automated control.

[0091] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered to be within the scope of this specification. When technical features of different embodiments are embodied in the same drawing, it can be regarded as the drawing also disclosing examples of combinations of the various embodiments involved.

[0092] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. Therefore, the patent protection scope of this application should be determined by the appended claims.

Claims

1. A retractable folding lower die mechanism characterized by, The utility model relates to a bag-shaped cloth folding machine, comprising: a base; a lower mould plate, which adopts a split deformation structure and has an expanded working state and an opposite narrow state, the lower mould plate comprises a plurality of unit plates, and each unit plate is movably connected to the base; a driving mechanism, which is installed on the base and connected to each unit plate, is used for driving the lower mould plate to switch states.

2. The retractable folding under die mechanism of claim 1 wherein, The unit plate comprises: a middle plate, which moves along a first direction; side plates, which comprise a left plate and a right plate arranged on both sides of the middle plate along a second direction, and the left plate and the right plate move along the second direction; the base has opposite front and back sides, the first direction extends along the front-back direction, and the second direction is perpendicular to the first direction.

3. The retractable folding under die mechanism of claim 2, wherein, Each unit plate is independently configured with the driving mechanism; or each unit plate shares the same set of driving mechanisms, and the left plate and the right plate move synchronously and reversely.

4. The retractable folding under die mechanism of claim 2 wherein, The base and the side plates are connected by elastic members, which make the lower mould plate tend to the narrow state or the working state.

5. The retractable folding under die mechanism of claim 2 wherein, In the working state, the front edges of each unit plate are connected to each other; in the narrow state, the middle plate further approaches the base along the first direction, and the left plate and the right plate approach each other to surround the front side of the middle plate.

6. The retractable folding under die mechanism of claim 5 wherein, The left plate and the right plate are respectively provided with an avoiding area on the side facing each other, and in the narrow state, the front side of the middle plate is located in the avoiding area.

7. The retractable folding under die mechanism of claim 2 wherein, The driving mechanism comprises: a cylinder, which is installed on the base, and the middle plate is connected to the piston rod of the cylinder; a connecting rod, which is two, one end of each connecting rod is hinged to the piston rod of the cylinder, and the other end is hinged to each side plate.

8. The retractable folding under die mechanism of claim 7, wherein, The piston rod of the cylinder is provided with a stroke adjusting member, which interacts with the cylinder body to limit the retraction limit position of the piston rod.

9. The retractable folding under die mechanism of claim 2 wherein, All unit plates are arranged in the same plane; the left plate and the right plate are respectively provided with an avoiding groove on the side facing away from each other, which is used for placing the folded edge of the bag-shaped cloth.

10. A bag sealer comprising an upper die mechanism and a lower die mechanism cooperating to hold a bag-shaped web of material to perform a hem, characterized by, The lower mould mechanism is the retractable and foldable lower mould mechanism in any one of claims 1-9; the upper mould mechanism is provided with a plurality of sets of force applying assemblies, each set of force applying assembly acts on a corresponding unit plate, and each set of force applying assembly comprises a suction member for keeping the unit plate and the upper mould mechanism clamping the bag-shaped cloth and a pushing member for driving the unit plate to separate from the upper mould mechanism.

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