Ultrasonic welding head for spot welding bag bottom

Abstract

The utility model discloses a spot welding bag bottom ultrasonic welding head which is characterized in that a K-shaped convex plate (comprising a linear part and an inclined part) is arranged at the lower end of a body, a partition groove and a small pressing block are arranged in the middle of the linear part, a triangular pressing strip (with a flat tip) and a U-shaped open groove of the inclined part are arranged on the end face of the convex plate, and a vertical through groove is formed in the body. The welding head is used for welding the bag bottom of the plastic packaging bag to form a side-turning K-shaped suture line (the inclined suture line supports the bottom and the transverse suture line reinforces) and an additional straight suture line, so that the bag bottom forms a square opening surface, the problem of unstable placement caused by traditional linear welding is solved, and the welding head is suitable for the fields of express packaging and the like. The structure is simple and the welding stability is high.

Description

TECHNICAL FIELD

[0001] The utility model relates to ultrasonic welding technical field, concretely relates to a spot welding bag bottom ultrasonic welding head for plastic packaging bag bag bottom welding. BACKGROUND

[0002] The ultrasonic welding equipment is mainly composed of five parts: a high-frequency current generator, a transducer, an amplitude-varying rod, a welding head and a base. The welding head design needs to match the workpiece profile to ensure that the vibration energy is concentrated on the welding interface

[0003] The welding head directly determines the profile and welding quality of the welding. When the traditional plastic packaging bag is welded, the front bag surface and the rear bag surface are directly stitched by the linear welding head, which makes it difficult to form a flat supporting surface on the bag bottom, and the placed objects are prone to tilt, especially in express transportation. SUMMARY

[0004] To solve the above problems, the utility model aims at providing a welding head capable of forming a square supporting surface to improve the load-bearing stability of the bag bottom.

[0005] To achieve the above-mentioned purpose, the utility model provides the following technical scheme: a spot welding bag bottom ultrasonic welding head, comprising a body, a "K" shaped protruding plate is arranged on the lower end face of the body, the protruding plate comprises a straight line part and two inclined parts, a partition groove is arranged in the middle of the straight line part, a small pressing block is arranged on the groove bottom of the partition groove, the cross section of the protruding plate is isosceles trapezoidal, pressing strips are arranged in sequence on the end face of the protruding plate, the pressing strips are triangular blocks and the sharp part is a flat surface, a "U" shaped opening groove is arranged in the middle of the pressing strips on the end face of the inclined part, and vertical through grooves are arranged on the body.

[0006] After the "K" shaped protruding plate is welded by ultrasonic waves to stitch the two sides of the bottom of the front bag surface and the rear bag surface of the packaging bag, a side-up "K" shaped welding stitching line structure and another straight strip welding stitching line are formed, which together constitute a square supporting surface.

[0007] The partition groove is used to form a supporting part after welding, and the small pressing block is used to enhance the local strength of the supporting part.

[0008] The vertical through groove is arranged at the transverse node of ultrasonic vibration to destroy the transverse vibration transmission and ensure the concentration of longitudinal vibration energy.

[0009] The utility model has the advantages of:

[0010] 1. The "K" shaped welding line provides multidirectional support, and the bag bottom forms a stable square supporting surface.

[0011] 2. The partition groove and the small pressing block strengthen the supporting part structure.

[0012] 3. Vertical slots suppress lateral vibration and ensure efficient longitudinal energy transfer;

[0013] 4. Improve the flatness of the tip of the pressure strip and optimize the local welding precision of the opening groove.

[0014] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0015] Figure 1 This is a perspective view of a specific embodiment of the present utility model;

[0016] Figure 2 This is a cross-sectional view of a specific embodiment of the present utility model;

[0017] Figure 3 This is a structural diagram of the side of the packaging bag after ultrasonic welding.

[0018] Explanation of reference numerals in the attached drawings: 1 Body, 2 Convex plate, 21 Straight section, 22 Inclined section, 3 Partition groove, 4 Small pressing block, 5 Pressing strip, 6 Opening groove, 7 Vertical through groove, 10 Packaging bag, 101 Square opening surface, 102 Diagonal stitch, 103 Horizontal support section, 104 Straight stitch. Detailed Implementation

[0019] The present invention will be specifically described below through embodiments, which are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention.

[0020] like Figure 1 , Figure 2 As shown, this embodiment provides an ultrasonic welding head for spot welding bag bottoms, used for ultrasonic welding of the bottoms of plastic packaging bags (such as express packaging bags, food packaging bags, etc.), which mainly solves the problems of uneven bag bottoms and easy tipping of items caused by traditional straight welding.

[0021] Overall structure of the welding head

[0022] like Figures 1 to 3 As shown, the welding head includes the following core components:

[0023] Body 1: This is the main support structure of the welding head, usually made of metal materials with good ultrasonic conductivity such as titanium alloy, aluminum alloy or stainless steel. Its upper end is connected to the amplitude transformer of the ultrasonic equipment (to receive longitudinal vibration energy), and its lower end is used to install the welding execution structure (i.e., the protruding plate 2). A through-type material shortage groove is set in the middle to reduce weight.

[0024] Convex plate 2: Fixed to the lower end face of body 1, it has a three-dimensional "K" shape and is a key welding actuator that directly acts on the bottom of the packaging bag. Specifically, it includes:

[0025] Straight part 21: the middle vertical section of the "K" shape, extending in the vertical direction (perpendicular to the lower end surface of the body 1), used to form the vertical welding seam in the middle of the bag bottom.

[0026] Inclined part 22: the two side inclined sections of the "K" shape, respectively connected to the two ends of the bottom of the straight part 21, extending obliquely downward (with an acute angle of, for example, 45°~60° to the straight part 21), the two inclined parts 22 are symmetrically distributed, together with the straight part 21 to form the planar projection contour of the "K" shape.

[0027] Partition groove 3: opened in the middle of the straight part 21 (centered along the length direction of the straight part 21), a transverse groove (depth about 0.5~2mm, width about 1~3mm) through the thickness of the flange 2, used to block the complete fusion of the cloth at this position during welding, thereby forming a "support part" (i.e. a flexible area where the subsequent bag bottom can be naturally expanded) in the middle of the welded bag bottom.

[0028] Small pressing block 4: embedded in the groove bottom of the partition groove 3 (by integral processing or later fixation), a protrusion matching the shape of the partition groove 3 (height slightly lower than the end surface of the flange 2, for example, 0.1~0.3mm lower), which functions to ensure the fusion strength of the edge of the support part (avoiding the bag bottom cracking caused by excessive separation of the support part) by applying local pressure to the cloth through the small pressing block 4 while the partition groove 3 blocks the fusion.

[0029] Pressing strip 5: evenly distributed on the entire end surface of the flange 2 (including the end surface of the straight part 21 and the inclined part 22), each pressing strip 5 is in the shape of a triangular block (cross section is an isosceles triangle), the tip (i.e. the top angle of the triangle) is processed into a flat surface (for example, by grinding or polishing treatment), used to apply concentrated and uniform pressure to the cloth during welding to ensure consistent energy density of the welding interface. The middle of the pressing strip 5 on the end surface of the inclined part 22 is also provided with a "U" shaped open slot 6, the width of the open slot 6 is about 0.8~2mm, and the depth is about 0.3~1mm, used to avoid excessive fusion of the end of the inclined part 22 (prevent local burning caused by concentrated welding energy), while assisting in forming the flexible transition of the inclined seam line.

[0030] Vertical slot 7: evenly opened in the body 1 along the axial direction of the body 1 (i.e. perpendicular to the upper / lower end surface of the body 1), usually located at the transverse node position of ultrasonic vibration (i.e. the position where the transverse vibration amplitude is the smallest, which can be determined by finite element analysis). The vertical slot 7 is a straight slot (width about 0.5-1.5mm, depth about 2-5mm), which can destroy the transmission path of transverse vibration and force the ultrasonic energy to be transmitted to the convex plate 2 in the form of longitudinal vibration (perpendicular to the end surface of the body 1), so as to ensure that the welding energy is fully applied to the longitudinal stitching of the bag bottom (avoiding the transverse vibration causing welding misalignment or energy dispersion).

[0031] Welding process and bag bottom forming principle:

[0032] In use, the welding head is installed at the end of the amplitude rod of the ultrasonic welding equipment, and the longitudinal vibration is generated by the high-frequency current generator to drive the transducer, which is amplified by the amplitude rod and transmitted to the welding head body 1, and finally the vibration energy is concentrated on the bag bottom of the plastic packaging bag by the end surface of the convex plate 2. The specific welding steps are as follows:

[0033] 1. Bag bottom positioning: unfold the front and rear bag surfaces of the plastic packaging bag, and align the two sides of the bottom (the welding area needs to be pre-coated with ultrasonic welding aid or directly use the melting characteristics of the plastic itself).

[0034] 2. First welding (K-shaped stitching): the convex plate 2 of the welding head is used to weld the two sides of the bottom of the front and rear bag surfaces of the packaging bag. When welding, the straight part 21 and the two inclined parts 22 of the convex plate 2 contact the bag bottom cloth at the same time: the middle part of the straight part 21 only forms fusion at the two side edges due to the existence of the partition slot 3 (the middle part is pressed by the small pressing block 4 but not completely bonded), finally forming a horizontal "supporting part" (i.e. the movable area in the middle of the bag bottom); the two inclined parts 22 are respectively fused with the inclined edges of the front and rear bag surfaces, forming two inclined "side turning stitching lines" (i.e. the inclined edges of the "K" shape); the pressing strip 5 (with "U" shaped opening slot 6) on the end surface of the inclined part 22 ensures the uniform fusion of the edge of the inclined stitching line, and the opening slot 6 avoids local overheating. Finally, the two sides of the bag bottom are stitched to form a side turning "K" shaped welding stitching line (including two inclined stitching lines and a horizontal supporting part), and the two inclined stitching lines naturally open outward, providing a bottom opening force for the bag bottom.

[0035] 3. Second welding (horizontal reinforcement): another conventional straight strip-shaped welding head (not the welding head of the present application) is used to perform secondary ultrasonic welding on the bottom and side surfaces of the front and rear bag surfaces of the packaging bag, forming one or more straight strip-shaped welding stitching lines (for example, along the horizontal center line or both sides of the bag bottom). The straight strip stitching line and the "K" shaped stitching line work together to further reinforce the horizontal stability of the bag bottom.

[0036] 4. Final bag bottom structure: such as Figure 3 As shown, after two welding processes, the bottom of the packaging bag 10 forms a "square support surface" 101. The "K"-shaped diagonal stitching 102 supports the two sides of the bottom of the bag outward (similar to the diagonal structure of a "tent"). The lateral support part 103 (the incompletely fused area corresponding to the partition groove 3) provides intermediate cushioning, while the straight stitching 104 constrains lateral deformation, ultimately making the bottom of the bag present a flat square plane (similar to the bottom of a box), which can stably support items (such as express parcels, food, etc.) and prevent it from tipping over when placed.

[0037] III. Verification of the role of key designs:

[0038] The “K”-shaped protrusion 2 and the partition groove 3: The partition groove 3 blocks the complete fusion in the middle of the straight part 21 to form a support part. Combined with the oblique stitching of the two inclined parts 22, the bottom of the bag naturally forms an outward-opening “triangular support structure” to ensure that the bottom is flat and not easy to collapse.

[0039] The triangular block-shaped tip (flat tip) of pressure strip 5: concentrates welding energy on the flat tip surface, ensuring uniform fusion strength of the suture line and avoiding energy dispersion caused by traditional arc pressure heads.

[0040] Vertical through-groove 7: Disrupts energy transfer at the transverse vibration node, ensuring that more than 90% of the ultrasonic energy acts on the fabric in the form of longitudinal vibration (longitudinal vibration directly promotes fabric fusion, while transverse vibration may cause misalignment or incomplete welding), thus improving welding consistency and efficiency.

[0041] In summary, this embodiment achieves precise welding of the bottom of the plastic packaging bag and the forming of the square open surface through the coordinated design of the "K"-shaped protrusion 2, the partition groove 3, the pressure strip 5, and the vertical through groove 7. It solves the stability defects of traditional straight welding and is especially suitable for the express delivery and food packaging fields where load-bearing capacity and placement stability are high.

Claims

1. A spot-welding pocket-bottom ultrasonic horn comprising a body (1), characterized in that, The lower end surface of the body (1) is provided with a "K" shaped protruding plate (2), the protruding plate (2) comprises a straight line part (21) and two inclined parts (22), the middle part of the straight line part (21) is provided with a partition groove (3), the groove bottom of the partition groove (3) is provided with a small pressing block (4), the cross section of the protruding plate (2) is isosceles trapezoidal, the end surface of the protruding plate (2) is provided with pressing strips (5) arranged in sequence, the pressing strips (5) are triangular blocks and the sharp part is a flat surface, the middle part of the pressing strips (5) on the end surface of the inclined part (22) is provided with a "U" shaped opening groove (6), the body (1) is provided with uniformly distributed vertical through grooves (7).

2. The spot-weld pocket horn of claim 1, wherein, The partition groove (3) is used to form a support part after welding and sewing, and the small pressing block (4) is used to enhance the local strength of the support part.

3. The spot pocket bottom ultrasonic horn of claim 1, wherein, The vertical through groove (7) is arranged at the transverse node of ultrasonic vibration, which is used to destroy the transverse vibration transmission and ensure the concentration of longitudinal vibration energy.

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