Horizontal bag feeding device of bag feeding type packaging machine
By designing a horizontal bag-up device in a bag-feeding packaging machine, using the combined structure of lifting seat, suction cup, rotating arm and flip arm, the traditional problem of low efficiency and poor reliability of the bag process is solved, and a more stable packaging bag is achieved Feeding improves packaging efficiency and quality.
Patent Information
- Application Number
- CN202421157149.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-26
- Publication Date
- 2024-12-27
- Estimated Expiration
- 2034-05-26
AI Technical Summary
The bag-loading process of traditional bag-type packaging machines relies on manual operation, which is inefficient and has poor reliability of the automatic bag-loading device, resulting in unstable loading process and increasing production costs.
A horizontal bag-up device for bag-type packaging machine is designed, including a work bench, a support mechanism, a material collection mechanism, a feeding mechanism and a driving mechanism, which collects materials through a lifting seat and a suction cup, and uses a rotating arm, a swing rod and a flip The combined structure of the arm realizes stable clamping and movement of the fixed jaw and the moving jaw, ensuring horizontal removal and stable upper bag of the packaging bag.
It significantly improves the bag stability of the packaging machine, which is far better than the existing technology, improves packaging efficiency and quality, and reduces production costs.
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Figure CN222247914U_ABST
Abstract
Description
Technical Field
[0001] The present application belongs to the field of bag-feeding packaging machines, and more specifically, to a horizontal bag-feeding packaging machine. Background Art
[0002] In the development history of bag-feeding packaging machines, they have undergone continuous innovation and optimization, which provide more reliable guarantees for the packaging quality of products. However, there are still some significant defects in the bag-feeding packaging machine during the bagging process, which not only affect the packaging efficiency, but also reduce the packaging quality and increase the production cost. First of all, the bagging process of the traditional bag-feeding packaging machine mainly relies on manual operation. This means that workers need to manually place the bags into the feeding port of the packaging machine, which is not only inefficient but also labor-intensive. In addition, there are also some automatic bagging devices specially configured for bag-feeding packaging machines on the market, but most of them have poor reliability and unstable feeding process. Therefore, it is necessary to solve the above technical problems. Summary of the invention
[0003] The purpose of the embodiments of the present application is to provide a horizontal bag feeding device for a bag-type packaging machine to solve the technical problem of unstable feeding process of the packaging machine in the prior art.
[0004] In order to achieve the above-mentioned purpose, the technical solution adopted in the present application is: to provide a horizontal bag feeding device for a bag-feeding packaging machine, comprising:
[0005] Workbench;
[0006] A supporting mechanism, comprising a frame and pillars installed at intervals on the same side of the workbench;
[0007] A bag bin connected to the support and forming a discharge port toward the worktable;
[0008] A material taking mechanism, comprising a lifting seat capable of rising and falling relative to the worktable and a suction cup mounted on the lifting seat, the suction cup facing the material discharge port;
[0009] The feeding mechanism comprises a rotating arm and a swing rod which are hinged to the frame at intervals and whose rotation planes are parallel to each other, wherein the rotation center axis of the swing rod is farther away from the worktable than the rotation center axis of the rotating arm, and the feeding mechanism further comprises a flip arm which is hinged to the swing rod and the rotating arm, wherein one end of the flip arm which is away from the swing rod is connected with a fixed jaw and a movable jaw which can move closer to or farther away from each other;
[0010] The driving mechanism is transmission-connected to the rotating arm and is used for driving the rotating arm to rotate relative to the frame.
[0011] Optionally, the driving mechanism comprises a support connected to the frame and a follower shaft rotatably connected to the rotating arm and parallel to the worktable, one end of the swing arm away from the rotating arm is hinged on the support, and the flip arm is connected to the follower shaft via a rotating seat connected to the follower shaft and a connecting bearing arranged between the rotating seat and the follower shaft;
[0012] The flip arm is spaced apart from the frame via the support and the follower shaft.
[0013] Optionally, the driving mechanism comprises a transmission shaft driven by an external power source and a first cam and a second cam connected to the transmission shaft at intervals;
[0014] A first roller, a first swing arm, a first pull rod, a second swing arm and a rotating shaft are sequentially connected between the first cam and the rotating arm, and a first bearing seat for supporting the first swing arm is connected to an end of the first swing arm away from the first pull rod;
[0015] The second cam and the lifting seat are sequentially connected with a second roller, a third swing arm, a second pull rod, a cross arm and a lifting rod, and one end of the third swing arm away from the second pull rod is connected with a second bearing seat for supporting the third swing arm.
[0016] Optionally, the transmission shaft and the supporting mechanism are distributed on both sides of the workbench, and the first pull rod and the lifting rod pass through the workbench.
[0017] Optionally, the second swing arm is arranged inside the frame, and the first pull rod extends from the outside of the frame into the inside of the frame and is transmission-connected to the second swing arm.
[0018] Optionally, the driving mechanism further comprises a guide cylinder connected to the workbench and slidably connected to the lifting rod.
[0019] Optionally, the driving mechanism further comprises a sliding sleeve connected to the cross arm and a guide column slidably connected to the sliding sleeve;
[0020] The guide column is parallel to the guide cylinder.
[0021] Optionally, the feeding mechanism further comprises a cylinder arranged inside the flip arm and a rotating block hinged to the power end of the cylinder through a pin shaft;
[0022] The rotating block is also hinged to the flip arm through a shaft sleeve, the fixed jaw is connected to the flip arm, and the movable jaw is connected to the rotating block.
[0023] Optionally, rubber pads are respectively provided on the sides of the fixed jaw and the movable jaw that face each other.
[0024] Optionally, ends of the first pull rod, the second pull rod and the swing rod are provided with spherical bearings.
[0025] The beneficial effect of the horizontal bagging device of the bag-feeding packaging machine provided by the present application is that: compared with the prior art, the horizontal bagging device of the bag-feeding packaging machine provided by the present application is provided with a frame and a support connected to the workbench, wherein the top end of the support is connected to a bag bin with a material outlet facing the workbench. In this way, when the lifting seat included in the material taking mechanism is lifted and lowered relative to the workbench, the suction cup connected to the lifting seat can be driven to suck the packaging bag from the bag bin and keep it horizontal relative to the workbench outside the bag bin. According to the connection form of the rotating arm, the swing arm and the flip arm in the feeding mechanism, when the rotating arm rotates relative to the frame, the flip arm can be driven to flip, so that the fixed jaw and the movable jaw connected to the flip arm can be moved to the opposite sides of the packaging bag in a horizontal state, and the fixed jaw and the movable jaw can be close to each other to stably remove the packaging bag from the suction cup, and the fixed jaw and the movable jaw can be moved away from each other after flipping to the predetermined bagging position, thereby completing a bagging process of the horizontal bagging device of the bag-feeding packaging machine in the present application. Since all structures in the horizontal bag loading device of the bag-feeding packaging machine provided in the present application are rigidly connected and the fixed jaws and the movable jaws can stably remove the packaging bags from the suction cups each time, the bag loading stability of the packaging machine can be significantly improved, which is far superior to the existing technology. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.
[0027] Figure 1 A schematic diagram of the overall structure of a horizontal bag feeding device for a bag-feeding packaging machine provided in an embodiment of the present application;
[0028] Figure 2 Schematic diagram of the partial structure of the horizontal bag feeding device of the bag feeding packaging machine provided in the embodiment of the present application Figure 1 ;
[0029] Figure 3 Schematic diagram of the partial structure of the horizontal bag feeding device of the bag feeding packaging machine provided in the embodiment of the present application Figure 2 ;
[0030] Figure 4 A partial structural sectional view of a horizontal bag feeding device of a bag feeding packaging machine provided in an embodiment of the present application.
[0031] Among them, the reference numerals in the figure are: 101, workbench; 102, frame; 103, pillar; 104, bag bin; 105, lifting seat; 106, suction cup; 107, rotating arm; 108, swing rod; 109, flip arm; 110, fixed jaw; 111, movable jaw; 112, support; 113, follower shaft; 114, rotating seat; 115, connecting bearing; 116, transmission shaft; 117, first cam; 118, second cam; 119, first roller; 120, first swing arm; 121, the first pull rod; 122, the second swing arm; 123, the rotating shaft; 124, the first bearing seat; 125, the second roller; 126, the third swing arm; 127, the second pull rod; 128, the cross arm; 129, the lifting rod; 130, the second bearing seat; 131, the guide cylinder; 132, the sliding sleeve; 133, the guide column; 134, the cylinder; 135, the pin; 136, the rotating block; 137, the bushing; 138, the rubber pad; 139, the spherical bearing; 140, the machine clamp; 141, the packaging bag. DETAILED DESCRIPTION
[0032] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.
[0033] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.
[0034] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.
[0035] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.
[0036] Please also read Figures 1 to 4Now, a horizontal bag feeding device for a bag feeding packaging machine provided in an embodiment of the present application is described. The horizontal bag feeding device for a bag feeding packaging machine includes a workbench 101, a support mechanism, a bag bin 104, a material taking mechanism, a material feeding mechanism and a driving mechanism. Among them:
[0037] The supporting mechanism includes a frame 102 and a pillar 103 installed at intervals on the same side of the workbench 101, and a bag bin 104 is connected to the pillar 103 and forms a discharge port facing the workbench 101. The material taking mechanism includes a lifting seat 105 that can be raised and lowered relative to the workbench 101 and a suction cup 106 installed on the lifting seat 105. In order to facilitate material taking, the suction cup 106 faces the discharge port in this embodiment. The feeding mechanism includes a rotating arm 107 and a swing rod 108 that are hinged to the frame 102 at intervals and whose rotation planes are parallel to each other. The rotation center axis of the swing rod 108 is farther away from the workbench 101 than the rotation center axis of the rotating arm 107. The feeding mechanism also includes a flip arm 109 hinged to the swing rod 108 and the rotating arm 107. The end of the flip arm 109 that is away from the swing rod 108 is connected to a fixed jaw 110 and a movable jaw 111 that can move closer or farther away from each other. The driving mechanism is connected to the rotating arm 107 and is used to drive the rotating arm 107 to rotate relative to the frame 102. For the convenience of description, the present embodiment introduces a machine clamp 140 for connecting the feeding mechanism for description.
[0038] According to the above structure provided in this embodiment, when the lifting seat 105 included in the material picking mechanism is lifted or lowered relative to the workbench 101, the suction cup 106 connected to the lifting seat 105 can be driven to suck the packaging bag 141 from the bag bin 104 and keep it horizontal relative to the workbench 101 outside the bag bin 104. According to the connection form of the rotating arm 107, the rocker arm 108 and the flip arm 109 in the feeding mechanism, when the rotating arm 107 rotates relative to the frame 102, the flip arm 109 can be driven to flip, so that the fixed jaw 110 and the movable jaw 111 connected to the flip arm 109 can be moved to the opposite sides of the horizontal packaging bag 141. The fixed jaw 110 and the movable jaw 111 are close to each other to stably remove the packaging bag 141 from the suction cup 106. After flipping to the predetermined bag loading position, the fixed jaw 110 and the movable jaw 111 can move away from each other and rotate the packaging bag 141 to the subsequent matching machine clamp 140, thereby completing a bag loading process of the horizontal bag loading device of the bag packaging machine in this embodiment. Since all structures in the horizontal bag loading device of the bag-feeding packaging machine provided in this embodiment are rigidly connected and the fixed jaw 110 and the movable jaw 111 can stably remove the packaging bag 141 from the suction cup 106 each time, the bag loading stability of the packaging machine can be significantly improved, which is far superior to the existing technology.
[0039] In another embodiment of the present application, please refer to Figures 1 to 4The driving mechanism includes a support 112 connected to the frame 102 and a follower shaft 113 rotatably connected to the rotating arm 107 and parallel to the workbench 101. The end of the swing arm 108 away from the rotating arm 107 is hinged on the support 112. The flip arm 109 is connected to the follower shaft 113 through a rotating seat 114 connected to the follower shaft 113 and a connecting bearing 115 arranged between the rotating seat 114 and the follower shaft 113. The flip arm 109 is spaced apart from the frame 102 through the support 112 and the follower shaft 113. According to the above structure provided in this embodiment, since the flip arm 109 is spaced apart from the frame 102 through the support 112 and the follower shaft 113, a larger space can be provided for the rotation of the flip arm 109 and the transfer of the packaging bag 141, which is conducive to ensuring the structural integrity of the packaging bag 141 during the transfer process and has a better bagging effect. It can be understood that in this embodiment, the connecting bearing 115 can adopt a deep groove ball bearing commonly used in the art, which is beneficial to further improve the rotation smoothness between the rotating seat 114 and the follower shaft 113.
[0040] In another embodiment of the present application, please refer to Figures 1 to 4 The driving mechanism includes a transmission shaft 116 driven by an external power source and a first cam 117 and a second cam 118 connected to the transmission shaft 116 at intervals. The first cam 117 is sequentially connected to the rotating arm 107 by a first roller 119, a first swing arm 120, a first tie rod 121, a second swing arm 122 and a rotating shaft 123. The end of the first swing arm 120 away from the first tie rod 121 is connected to a first bearing seat 124 for supporting the first swing arm 120. The second cam 118 is sequentially connected to the lifting seat 105 by a second roller 125, a third swing arm 126, a second tie rod 127, a cross arm 128 and a lifting rod 129. The end of the third swing arm 126 away from the second tie rod 127 is connected to a second bearing seat 130 for supporting the third swing arm 126.
[0041] According to the above structure provided in this embodiment, when the transmission shaft 116 rotates under the driving action of an external power source, the first cam 117 and the second cam 118 connected to the transmission shaft 116 can be driven to rotate. When the first cam 117 rotates, the first swing arm 120 can be driven to swing through the first roller 119. The first swing arm 120 can pull the first pull rod 121 during the swinging process. The first pull rod 121 can also drive the second swing arm 122 and the rotating shaft 123 to rotate, thereby driving the rotating arm 107 connected to the rotating shaft 123 to rotate. When the second cam 118 rotates, the third swing arm 126 can be driven to swing through the second roller 125. The third swing arm 126 can also pull the second pull rod 127 and the cross arm 128 during the swinging process, thereby driving the lifting rod 129 to rise and fall relative to the workbench 101, and then driving the lifting seat 105 connected to the lifting rod 129 to rise and fall to complete the material taking process of the bagging device in this application. In order to provide better bag loading stability, the horizontal bag loading device of the bag feeding packaging machine provided in this embodiment also has a first bearing seat 124 for supporting the first swing arm 120 and a second bearing seat 130 for supporting the third swing arm 126, which can significantly improve the swinging stability of the first swing arm 120 and the third swing arm 126, which is conducive to further improving the bag loading stability of the horizontal bag loading device of the bag feeding packaging machine in this embodiment.
[0042] In another embodiment of the present application, please refer to Figures 1 to 4 , the transmission shaft 116 and the supporting mechanism are distributed on both sides of the workbench 101, and the first pull rod 121 and the lifting rod 129 pass through the workbench 101. According to the above structure provided in this embodiment, distributing the transmission shaft 116 and the supporting mechanism on both sides of the workbench 101 is conducive to avoiding motion interference between the suction cup 106 and the transmission shaft 116 and other mechanisms, and is conducive to further improving the bag loading stability of the horizontal bag loading device of the bag-feeding packaging machine in this embodiment.
[0043] In another embodiment of the present application, please refer to Figures 1 to 4 , the second swing arm 122 is arranged inside the frame 102, and the first pull rod 121 extends from the outside of the frame 102 into the inside of the frame 102 and is transmission-connected to the second swing arm 122. According to the above structure provided in this embodiment, arranging the second swing arm 122 and the first pull rod 121 and other structures inside the frame 102 is conducive to avoiding motion interference between them and the structures such as the flip arm 109 in the feeding mechanism, which is conducive to further improving the bag loading stability of the horizontal bag loading device of the bag-feeding packaging machine in this embodiment.
[0044] In another embodiment of the present application, please refer to Figures 1 to 4The driving mechanism further includes a guide cylinder 131 connected to the workbench 101 and slidably connected to the lifting rod 129. According to the above structure provided in this embodiment, the guide cylinder 131 can significantly improve the moving stability of the lifting rod 129 relative to the workbench 101, thereby facilitating further improving the bag loading stability of the horizontal bag loading device of the bag-feeding packaging machine in this embodiment.
[0045] In another embodiment of the present application, please refer to Figures 1 to 4 The driving mechanism further includes a sliding sleeve 132 connected to the cross arm 128 and a guide post 133 slidably connected to the sliding sleeve 132, and the guide post 133 is parallel to the guide cylinder 131. According to the above structure provided in this embodiment, the guide post 133 can cooperate with the guide cylinder 131 to provide guidance for the lifting rod 129 relative to the work table 101, which is conducive to further improving the bag loading stability of the horizontal bag loading device of the bag packaging machine in this embodiment.
[0046] In another embodiment of the present application, please refer to Figures 1 to 4 The feeding mechanism further includes a cylinder 134 disposed inside the flip arm 109 and a rotating block 136 hinged to the power end of the cylinder 134 through a pin 135. The rotating block 136 is also hinged to the flip arm 109 through a sleeve 137. The fixed jaw 110 is connected to the flip arm 109, and the movable jaw 111 is connected to the rotating block 136. According to the above structure provided in this embodiment, when the piston rod of the cylinder 134 is extended and retracted, the rotating block 136 can be driven to rotate forward and reverse relative to the flip arm 109, thereby achieving stable approach or stable separation of the fixed jaw 110 and the movable jaw 111, which is conducive to further improving the bag loading stability of the horizontal bag loading device of the bag-feeding packaging machine in this embodiment.
[0047] In another embodiment of the present application, please refer to Figures 1 to 4 The fixed jaw 110 and the movable jaw 111 are respectively provided with rubber pads 138 on the sides facing each other. According to the above structure provided in this embodiment, by providing the rubber pads 138 on the fixed jaw 110 and the movable jaw 111, it is helpful to avoid the fixed jaw 110 and the movable jaw 111 from causing damage to the packaging bag 141 during the process of clamping the packaging bag 141, which is helpful to further improve the bag loading stability of the horizontal bag loading device of the bag-feeding packaging machine in this embodiment.
[0048] In another embodiment of the present application, please refer to Figures 1 to 4, the ends of the first tie rod 121, the second tie rod 127 and the swing rod 108 are provided with joint bearings 139. According to the above structure provided in this embodiment, by providing joint bearings 139 at the ends of the first tie rod 121, the second tie rod 127 and the swing rod 108, it is beneficial to make the first tie rod 121, the second tie rod 127 and the swing rod 108 have better connection adaptability with other corresponding structures, which is beneficial to further improve the bag loading stability of the horizontal bag loading device of the bag-feeding packaging machine in this embodiment.
[0049] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.
Claims
1. A horizontal bag feeding device for a bag-feeding packaging machine, characterized in that: include: Workbench plate (101); A supporting mechanism, comprising a frame (102) and a support column (103) installed at intervals on the same side of the workbench (101); A bag bin (104) connected to the support column (103) and forming a discharge port facing the workbench (101); A material taking mechanism, comprising a lifting seat (105) capable of being raised and lowered relative to the workbench (101) and a suction cup (106) mounted on the lifting seat (105), wherein the suction cup (106) faces the material discharge port; A feeding mechanism, comprising a rotating arm (107) and a swing rod (108) which are hinged to the frame (102) at intervals and whose rotation planes are parallel to each other, wherein the rotation center axis of the swing rod (108) is further away from the worktable (101) than the rotation center axis of the rotating arm (107), and the feeding mechanism also comprises a flip arm (109) hinged to the swing rod (108) and the rotating arm (107), wherein an end of the flip arm (109) which is away from the swing rod (108) is connected to a fixed jaw (110) and a movable jaw (111) which can move closer to or farther away from each other; A driving mechanism is transmission-connected to the rotating arm (107) and is used to drive the rotating arm (107) to rotate relative to the frame (102).
2. The horizontal bag feeding device of the bag feeding packaging machine according to claim 1, characterized in that: The driving mechanism comprises a support (112) connected to the frame (102) and a follower shaft (113) rotatably connected to the rotating arm (107) and parallel to the workbench (101); one end of the swing arm (108) away from the rotating arm (107) is hinged on the support (112); the flip arm (109) is connected to the follower shaft (113) via a rotating seat (114) connected to the follower shaft (113) and a connecting bearing (115) provided between the rotating seat (114) and the follower shaft (113); The flip arm (109) is spaced apart from the frame (102) via the support (112) and the follower shaft (113).
3. The horizontal bag feeding device of the bag feeding packaging machine according to claim 1, characterized in that: The driving mechanism comprises a transmission shaft (116) driven by an external power source, and a first cam (117) and a second cam (118) connected to the transmission shaft (116) at intervals; A first roller (119), a first swing arm (120), a first pull rod (121), a second swing arm (122) and a rotating shaft (123) are sequentially connected in a transmission manner between the first cam (117) and the rotating arm (107); an end of the first swing arm (120) away from the first pull rod (121) is connected to a first bearing seat (124) for supporting the first swing arm (120); A second roller (125), a third swing arm (126), a second pull rod (127), a cross arm (128) and a lifting rod (129) are sequentially connected in a transmission manner between the second cam (118) and the lifting seat (105); an end of the third swing arm (126) away from the second pull rod (127) is connected to a second bearing seat (130) for supporting the third swing arm (126).
4. The horizontal bag feeding device of the bag feeding packaging machine according to claim 3, characterized in that: The transmission shaft (116) and the support mechanism are distributed on both sides of the workbench (101), and the first pull rod (121) and the lifting rod (129) pass through the workbench (101).
5. The horizontal bag feeding device of the bag feeding packaging machine according to claim 4, characterized in that: The second swing arm (122) is arranged inside the frame (102), and the first pull rod (121) extends from the outside of the frame (102) into the inside of the frame (102) and is transmission-connected to the second swing arm (122).
6. The horizontal bag feeding device of the bag feeding packaging machine according to claim 4, characterized in that: The driving mechanism further comprises a guide cylinder (131) connected to the workbench (101) and slidably connected to the lifting rod (129).
7. The horizontal bag feeding device of the bag feeding packaging machine according to claim 6, characterized in that: The driving mechanism further comprises a sliding sleeve (132) connected to the cross arm (128) and a guide column (133) slidably connected to the sliding sleeve (132); The guide column (133) is parallel to the guide cylinder (131).
8. The horizontal bag feeding device of the bag feeding packaging machine according to claim 1, characterized in that: The feeding mechanism further comprises a cylinder (134) arranged inside the flip arm (109) and a rotating block (136) hinged to the power end of the cylinder (134) via a pin (135); The rotating block (136) is also hinged to the flip arm (109) via a shaft sleeve (137), the fixed jaw (110) is connected to the flip arm (109), and the movable jaw (111) is connected to the rotating block (136).
9. The horizontal bag feeding device of the bag feeding packaging machine according to claim 8, characterized in that: Rubber pads (138) are respectively provided on the mutually facing sides of the fixed jaw (110) and the movable jaw (111).
10. The horizontal bag feeding device of the bag feeding packaging machine according to claim 3, characterized in that: Joint bearings (139) are provided at the ends of the first pull rod (121), the second pull rod (127) and the swing rod (108).
