An ultrasonic pressing structure of a post-injection traceless welding technology

Abstract

The utility model provides a kind of ultrasonic wave compression structure of no trace welding technology after injection molding is completed, belong to no trace welding technical field, this ultrasonic wave compression structure of no trace welding technology after injection molding is completed includes upper compression piece, lower compression piece, guiding positioning piece and ultrasonic wave energy transmission insert, the bottom of upper compression piece is provided with annular welding mesa, the inner ring guiding boss of annular welding mesa is formed by extending along radial direction inward, the top of lower compression piece is provided with the annular receiving mesa matched with annular welding mesa, the center position of annular receiving mesa is equipped with positioning groove, guiding positioning piece is columnar structure and its outer circumferential surface and the inner wall surface interference fit of positioning groove;It can solve the technical problems that welding position deviation and compression depth control improper cause welding interface to appear obvious trace or welding strength is insufficient in the ultrasonic wave welding process of injection molding part in prior art, resulting in insufficient welding positioning precision.

Description

Technical Field

[0001] This utility model belongs to the field of seamless welding technology, specifically, it relates to an ultrasonic pressing structure for seamless welding technology after injection molding. Background Technology

[0002] In the field of plastic product manufacturing, injection molding technology has become the mainstream process for producing various plastic parts. With the increasing complexity of product design and the improvement of functional integration, many products require the connection and assembly of multiple injection-molded parts through secondary processing. Ultrasonic welding, as a highly efficient plastic joining technology, is widely used in industries such as electronic product housings, automotive parts, medical devices, and home appliances due to its advantages such as fast welding speed, no need for adhesives, and high welding strength. Traditional ultrasonic welding methods typically employ simple planar butt joints or lap joints. High-frequency mechanical vibrations are generated by an ultrasonic generator, and the vibration energy is transmitted through the welding head to the contact interface of the plastic parts, causing frictional heat at the contact surface, which melts the plastic material. Under pressure, a weld bond is formed. However, existing ultrasonic welding structures generally suffer from insufficient positioning accuracy in practical applications. Due to the lack of effective guiding and limiting mechanisms, the upper and lower plastic parts are prone to relative displacement during the welding process, leading to deviations in the welding position. Another prominent issue in the design is the difficulty in precisely controlling the pressing depth. Operators often rely on experience or simple time control to determine the pressing endpoint. This leads to significant fluctuations in welding quality between different batches of products. Insufficient pressing results in welding strength that fails to meet usage requirements, while excessive pressing causes deformation of plastic parts or creates obvious indentations and flash at the welding interface, severely affecting the product's appearance. This is especially true in high-end consumer electronics and precision medical devices, where the requirements for a seamless product appearance are extremely stringent. The weld marks left by traditional welding methods have become a major bottleneck restricting the improvement of product quality. Although the industry has attempted to improve welding results by increasing welding parameter control precision or using special welding head designs, these methods often require complex equipment modifications and high costs, with limited improvement. Therefore, there is an urgent need for a new ultrasonic pressing structure that can solve the problems of positioning accuracy and pressing depth control from the structural design level, enabling high-quality, seamless welding. Utility Model Content

[0003] In view of this, the present invention provides an ultrasonic pressing structure for seamless welding technology after injection molding, which can solve the technical problems in the ultrasonic welding process of injection molded parts in the prior art, such as insufficient welding positioning accuracy leading to welding position displacement and improper pressing depth control causing obvious marks on the welding interface or insufficient welding strength. It can also solve the problems of traditional ultrasonic welding structures lacking precise guiding and limiting mechanisms and energy concentration transmission design, resulting in visible weld seams on the appearance of the welded product affecting aesthetics, and difficulty in ensuring the consistency and stability of welding quality.

[0004] This utility model is implemented as follows:

[0005] This utility model provides an ultrasonic pressing structure for seamless welding technology after injection molding, comprising an upper pressing component, a lower pressing component, a guide positioning component, and an ultrasonic energy transmission insert. The bottom of the upper pressing component has an annular welding platform, which extends radially inward to form an inner guide boss. The top of the lower pressing component has an annular receiving platform that matches the annular welding platform. A positioning groove is formed at the center of the annular receiving platform. The guide positioning component has a columnar structure, and its outer circumferential surface is interference-fitted with the inner wall of the positioning groove. The ultrasonic energy transmission insert is embedded inside the annular welding platform of the upper pressing component. The bottom of the ultrasonic energy transmission insert forms an ultrasonic action surface, which is located on the same plane as the annular welding platform or 0.05~0.2mm lower than the annular welding platform. The top of the guide positioning component contacts the bottom surface of the inner guide boss to limit the relative pressing depth between the upper and lower pressing components.

[0006] The technical effects of the ultrasonic pressing structure for seamless welding after injection molding provided by this utility model are as follows: By setting an annular welding platform at the bottom of the upper pressing part and cooperating with an inner ring guide boss on its inner side, and cooperating with the annular receiving platform and central positioning groove at the top of the lower pressing part, the guide positioning part can accurately control the relative position and pressing depth of the upper and lower pressing parts. The bottom ultrasonic action surface of the ultrasonic energy transmission insert and the annular welding platform form a synergistic action area to ensure that the ultrasonic energy is concentrated and transmitted to the welding interface. When the top of the guide positioning part contacts the bottom surface of the inner ring guide boss, the preset pressing depth is reached, which effectively prevents structural deformation caused by over-pressing or insufficient welding strength caused by under-pressing, and realizes precise positioning and controllable pressing in the injection molding process.

[0007] Based on the above technical solution, the ultrasonic pressing structure of the seamless welding technology after injection molding of this utility model can be further improved as follows:

[0008] The width of the annular welding platform is 1-3 mm in the radial direction, and the surface roughness of the annular welding platform is Ra0.4-Ra0.8.

[0009] The beneficial effects of adopting the above-mentioned improved scheme are as follows: by limiting the radial width of the annular welding table to 1~3mm and controlling the surface roughness within the range of Ra0.4~Ra0.8, the welding table has a suitable contact area and surface quality. The narrow annular welding table can concentrate the ultrasonic energy transmission efficiency and avoid uneven welding caused by energy dispersion. The appropriate surface roughness ensures sufficient friction to generate the heat required for welding, and avoids leaving obvious marks after welding on an overly rough surface, thus achieving a balance between welding strength and a mark-free surface effect.

[0010] Furthermore, the height of the inner ring guide boss is 0.1~0.5mm higher than the height of the annular welding platform, and the clearance fit accuracy between the inner diameter of the inner ring guide boss and the outer diameter of the guide positioning component is H7~H9.

[0011] The beneficial effects of adopting the above-mentioned improved scheme are as follows: By setting a height difference of 0.1~0.5mm between the inner ring guide boss and the annular welding table surface, and using a clearance fit with a precision of H7~H9, the guide positioning component can enter the guiding range of the inner ring guide boss in the initial stage of pressing, realizing the coaxiality control of the upper and lower pressing components. When the pressing force is continuously applied, the inner ring guide boss first contacts the top of the guide positioning component to form a limiting effect. At this time, the annular welding table surface and the annular receiving table surface still maintain a small gap or just contact, ensuring that the welding interface obtains sufficient energy transfer time under the action of ultrasound without wasting energy due to premature rigid contact, thereby improving the stability and consistency of welding quality.

[0012] Furthermore, the ultrasonic energy transmission insert has an annular cross-sectional structure, and the outer circumferential sidewall of the ultrasonic energy transmission insert forms an interference fit connection with the inner wall of the upper pressing component.

[0013] The beneficial effects of adopting the above-mentioned improved scheme are as follows: By using an annular cross-section structure for the ultrasonic energy transmission insert and forming an interference fit connection with the inner wall of the upper pressing component, ultrasonic energy can be uniformly and stably transmitted from the insert to the annular welding area. The annular structure ensures the uniform distribution of energy along the circumference, avoiding local energy concentration or insufficiency. The interference fit connection eliminates the relative displacement and vibration attenuation between the insert and the upper pressing component, ensuring efficient transmission of ultrasonic energy. At the same time, the design of the annular insert allows the central area to accommodate the guide positioning component, realizing a spatial composite layout of energy transmission and positioning functions, and improving the compactness and functional integration of the structure.

[0014] Furthermore, the outer edge of the annular receiving platform is provided with a guide chamfer, the angle of the guide chamfer is 30~60°, and the radial extension length of the guide chamfer is 0.3~0.8mm.

[0015] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: By setting a guide chamfer with an angle of 30~60° and a radial extension length of 0.3~0.8mm on the outer edge of the annular receiving platform, the upper pressing part can smoothly find the correct pressing position during the pressing process. The gradual transition structure of the guide chamfer effectively reduces the risk of stress concentration during initial contact, avoiding edge cracking or damage of plastic parts caused by hard contact. At the same time, the chamfer structure provides a self-centering function for the pressing process. Even if there is a slight initial offset, it can be automatically corrected by the guiding effect of the chamfer, reducing the dependence on operational precision and improving production efficiency and yield.

[0016] Furthermore, the depth of the positioning groove is greater than 1.2 to 1.8 times the length of the guide positioning part insertion portion, and the bottom of the positioning groove forms a receiving space to receive the overflow of molten material generated during the pressing process.

[0017] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: by setting the depth of the positioning groove to 1.2 to 1.8 times the insertion length of the guide positioning component, and forming a receiving space at the bottom of the groove, the molten material overflowing due to ultrasonic action during the pressing process has a sufficient receiving area, avoiding appearance defects and pollution problems caused by the outward overflow of molten material. The deeper groove design ensures that the guide positioning component maintains a stable guiding role throughout the entire pressing stroke, and will not fail to position due to insufficient space at the end of the stroke. At the same time, the existence of the bottom receiving space also plays a buffering role, reducing the adverse effects of the impact force at the end of pressing on the welding interface, and protecting the formed welding bond layer from being damaged.

[0018] Furthermore, multiple micro-protruding tooth structures are uniformly distributed on the ultrasonic action surface. The height of the micro-protruding tooth structure is 0.02~0.08mm, and the spacing between adjacent micro-protruding tooth structures is 0.1~0.3mm.

[0019] The beneficial effects of the above-mentioned improved scheme are as follows: By uniformly distributing multiple micro-protruding tooth structures with a height of 0.02~0.08mm and a spacing of 0.1~0.3mm on the ultrasonic action surface, the ultrasonic energy can be concentrated on the corresponding receiving platform through the tips of these micro-protruding teeth. Under ultrasonic vibration, the micro-protruding tooth structure generates high-frequency friction and deformation with the receiving platform, quickly generating the local high temperature required for welding. The distributed layout of multiple micro-protruding teeth ensures the uniform distribution of heat throughout the entire annular welding area. The tiny tooth height can be completely integrated into the base material without leaving any trace after welding. The appropriate spacing ensures sufficient energy application point density and avoids overheating caused by heat interference between adjacent teeth, thus achieving a unity of efficient welding and a seamless appearance.

[0020] Furthermore, both the upper and lower pressing components are made of polycarbonate or acrylonitrile butadiene styrene copolymer, and the ultrasonic energy transmission insert is made of titanium alloy or aluminum alloy.

[0021] The beneficial effects of adopting the above-mentioned improved scheme are as follows: By selecting polycarbonate or acrylonitrile butadiene styrene copolymer as the material for the upper and lower pressing parts, and combining it with ultrasonic energy conduction inserts made of titanium alloy or aluminum alloy, the good absorption characteristics of plastic materials for ultrasonic energy and the high-efficiency energy conduction characteristics of metal materials are fully utilized. Under the action of ultrasound, polycarbonate and acrylonitrile butadiene styrene copolymer can quickly reach the melting temperature to form a reliable molecular chain cross-linking bond. The titanium alloy or aluminum alloy insert has excellent sound wave conduction performance and mechanical strength, and can withstand ultrasonic vibration for a long time without fatigue damage. This material combination ensures the high efficiency of the welding process and the service life of the equipment. At the same time, the same plastic material ensures the material compatibility of the welding interface and obtains a welding effect with strength close to that of the base material.

[0022] Furthermore, the guide positioning component is made of stainless steel, and the top surface of the guide positioning component forms a spherical crown structure, the radius of curvature of the spherical crown structure being 0.8 to 1.5 times the outer diameter of the guide positioning component.

[0023] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: By using stainless steel to make the guide positioning component and forming a spherical crown structure with a curvature radius of 0.8 to 1.5 times the outer diameter at its top, the guide positioning component has high strength and wear resistance to cope with mechanical contact during repeated use. When the spherical crown structure contacts the bottom surface of the inner ring guide boss, it forms a point contact or small area contact state. This contact method can accurately transmit the pressing termination signal without affecting the smoothness of the pressing process due to frictional resistance caused by excessive contact surface. The smooth transition of the spherical crown surface also has a self-cleaning function, making it difficult to accumulate molten material residues and maintaining the stability of positioning accuracy during long-term use. The corrosion resistance of stainless steel ensures reliability in various production environments.

[0024] Furthermore, the contact line width between the annular welding platform and the annular receiving platform in the pressed state is less than 0.5 mm, and the outer wall surface of the upper pressing component and the outer wall surface of the lower pressing component form a continuous outer surface without step transition after pressing.

[0025] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: By controlling the contact line width after the annular welding table and the annular receiving table are pressed together to be less than 0.5mm, and making the outer wall surfaces of the upper and lower pressed parts form a continuous outer surface without step transition, the welding marks are minimized and the appearance is integrated. The narrow contact line width means that the welding area is restricted to a very small range. The heat-affected zone and possible color difference changes generated during the welding process are controlled to a degree that is difficult to detect with the naked eye. The stepless transition design eliminates the joint protrusion or depression problem common in traditional welding methods, so that the product appearance presents a perfect continuity, which meets the strict requirements of high-end products for appearance quality. At the same time, this structural design also improves the sealing performance and the uniformity of the overall strength distribution of the product, and avoids the generation of stress concentration points.

[0026] Compared with existing technologies, the beneficial effects of the ultrasonic pressing structure for seamless welding after injection molding provided by this utility model are as follows: This utility model innovatively designs an upper pressing component structure including an annular welding platform and an inner guide boss, combined with a lower pressing component with positioning grooves and a columnar guide positioning component, to construct a precise three-dimensional positioning constraint system. The embedded layout of the ultrasonic energy transmission insert achieves efficient and concentrated energy transmission. The overall structure can ensure precise control of the coaxiality and pressing depth of the upper and lower pressing components during the welding process. Through the narrow design of the annular welding platform and the application of the micro-protruding tooth structure, ultrasonic energy is focused on a very small welding area, rapidly generating local high temperatures to achieve molecular-level melting and bonding. The limiting and matching mechanism between the guide positioning component and the inner ring guide boss ensures that the pressing process stops accurately when the optimal welding state is reached, avoiding structural deformation caused by excessive pressing. The contact line width after welding is controlled within 0.5mm, and the appearance presents a continuous surface without step transition, achieving a truly seamless welding effect. Compared with existing technologies, this structure not only significantly improves the welding positioning accuracy and the stability of pressing depth control, but also greatly improves the appearance quality after welding, eliminating visible welds. At the same time, through reasonable material selection and structural optimization, the welding strength reaches or approaches the strength level of the base material, meeting the dual requirements of modern industrial products for high-quality appearance and reliable performance, and has broad application value and promotion prospects. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments of this utility model will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of an ultrasonic pressing structure using a seamless welding technique after injection molding.

[0029] Figure 2 This is a structural schematic diagram of the pressing assembly;

[0030] Figure 3 This is a schematic diagram of the structure of the ultrasonic wave action surface;

[0031] The attached diagram lists the components represented by each number as follows:

[0032] 10. Upper pressing component; 20. Lower pressing component; 30. Guide and positioning component; 40. Ultrasonic energy transmission insert. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings.

[0034] like Figure 1-3 The diagram shows a schematic of an ultrasonic pressing structure for a seamless welding technology after injection molding provided by this utility model. The structure includes an upper pressing component 10, a lower pressing component 20, a guide positioning component 30, and an ultrasonic energy transmission insert 40. The bottom of the upper pressing component has an annular welding platform, which extends radially inward to form an inner guide boss. The top of the lower pressing component has an annular receiving platform that matches the annular welding platform. A positioning groove is formed at the center of the annular receiving platform. The guide positioning component has a columnar structure, and its outer circumferential surface is interference-fitted with the inner wall of the positioning groove. The ultrasonic energy transmission insert is embedded inside the annular welding platform of the upper pressing component. The bottom of the ultrasonic energy transmission insert forms an ultrasonic action surface, which is on the same plane as the annular welding platform or 0.05~0.2mm lower than the annular welding platform. The top of the guide positioning component contacts the bottom surface of the inner guide boss to limit the relative pressing depth between the upper and lower pressing components.

[0035] In the above technical solution, the width of the annular welding platform is 1~3mm in the radial direction, and the surface roughness of the annular welding platform is Ra0.4~Ra0.8.

[0036] Furthermore, in the above technical solution, the height of the inner ring guide boss is 0.1~0.5mm higher than the height of the annular welding table, and the clearance fit accuracy between the inner diameter of the inner ring guide boss and the outer diameter of the guide positioning part is H7~H9.

[0037] Furthermore, in the above technical solution, the ultrasonic energy transmission insert has an annular cross-sectional structure, and the outer circumferential sidewall of the ultrasonic energy transmission insert forms an interference fit connection with the inner wall of the upper pressing component.

[0038] Furthermore, in the above technical solution, the outer edge of the annular receiving platform is provided with a guide chamfer, the angle of the guide chamfer is 30~60°, and the radial extension length of the guide chamfer is 0.3~0.8mm.

[0039] Furthermore, in the above technical solution, the depth of the positioning groove is 1.2 to 1.8 times greater than the length of the guide positioning part insertion portion, and the bottom of the positioning groove forms a receiving space to receive the overflow of molten material generated during the pressing process.

[0040] Furthermore, in the above technical solution, multiple micro-protruding tooth structures are uniformly distributed on the ultrasonic action surface. The height of the micro-protruding tooth structure is 0.02~0.08mm, and the spacing between adjacent micro-protruding tooth structures is 0.1~0.3mm.

[0041] Furthermore, in the above technical solution, both the upper and lower pressing parts are made of polycarbonate or acrylonitrile butadiene styrene copolymer, and the ultrasonic energy transmission insert is made of titanium alloy or aluminum alloy.

[0042] Furthermore, in the above technical solution, the guide positioning component is made of stainless steel, and the top surface of the guide positioning component forms a spherical crown structure, the radius of curvature of the spherical crown structure being 0.8 to 1.5 times the outer diameter of the guide positioning component.

[0043] Furthermore, in the above technical solution, the contact line width between the annular welding platform and the annular receiving platform under the pressing state is less than 0.5mm, and the outer wall surface of the upper pressing part and the outer wall surface of the lower pressing part form a continuous outer surface without step transition after pressing.

[0044] The following is a specific embodiment 1 of this utility model: This embodiment provides an ultrasonic pressing structure for assembling electronic product casings. The upper pressing part is made of transparent polycarbonate material through injection molding, and has an overall cylindrical structure with an outer diameter of 45mm and a wall thickness of 2.5mm. The bottom annular welding platform is located on the inner side of the outer wall. The radial width of the annular welding platform is 2mm, and the surface is precision machined to a roughness of Ra0.6. The inner ring guide boss formed by the inward extension of the annular welding platform has a height of 0.3mm and an inner diameter of 20mm. The inner wall surface of the guide boss is perpendicular to the axial direction. The machining accuracy is controlled according to H8 tolerance. The ultrasonic energy transmission insert is made of titanium alloy material and is manufactured using wire cutting and precision machining. The insert is machined using a grinding process. It has an annular cross-section with an outer diameter of 38mm, an inner diameter of 22mm, and a wall thickness of 1.5mm. The insert is cold-pressed into the upper pressing component. The interference fit between the outer circumference of the insert and the inner wall of the upper pressing component is 0.08mm, ensuring a tight fit without relative slippage. The ultrasonic action surface at the bottom of the insert is coplanar with the annular welding platform. 36 micro-protrusions are evenly distributed on the action surface. Each micro-protrusion is triangular pyramidal in shape, 0.05mm high, with a base width of 0.15mm, and a circumferential distance of 0.2mm between adjacent micro-protrusions. The lower pressing component is also made of polycarbonate, with the same outer diameter of 45mm as the upper pressing component. The width of the annular receiving platform at the top is 2.2mm, slightly wider than the annular welding platform. The surface is designed to provide tolerance for mating. The surface roughness of the receiving platform is Ra0.8, and the outer edge has a 45° guide chamfer with a radial extension length of 0.5mm. The positioning groove at the center is 12mm deep and has an inner diameter of 15.5mm. A 4mm deep accommodating space is reserved at the bottom of the groove to collect any molten material that may overflow during the pressing process. The guide positioning component is made of 304 stainless steel and is machined into a solid cylindrical shape with an outer diameter of 15.48mm and a length of 10mm. It forms a 0.02mm interference fit with the positioning groove. The top of the guide positioning component is machined into a spherical crown with a radius of curvature of 18mm. The surface is polished to a mirror finish to reduce frictional resistance. During use, the guide positioning component... The upper part is pressed into the positioning groove of the lower pressing part by a press machine to a depth of 8mm and an exposed length of 2mm. The lower pressing part is placed on the lower tooling platform of the ultrasonic welding machine and fixed by positioning pins. The upper pressing part is connected to a 20 kHz ultrasonic welding head. The welding parameters are set as follows: amplitude 55μm, welding time 1.2 seconds, pressing pressure 0.35 MPa, and trigger delay 0.1 seconds. During the welding process, the ultrasonic energy is efficiently transmitted to the tip of the micro-protrusion through the titanium alloy insert. The local contact between the micro-protrusion and the receiving platform generates an instantaneous high temperature exceeding the melting point of polycarbonate, 260°C. The material melts rapidly and flows and fills under pressure. The pressing stops when the inner ring guide boss contacts the top of the guide positioning part. At this time, a width of approximately 0.The 3mm weld bonding layer, after cooling and solidification, was inspected and found to have a perfectly continuous transition at the weld interface. Weld marks were indistinguishable to the naked eye under natural light. Tensile testing showed that the weld strength reached 92% of the base material strength, meeting product usage requirements.

[0045] The following is another specific embodiment 2 of this utility model: Embodiment 2 is an improvement on Embodiment 1, targeting applications requiring higher welding strength. The number of micro-protrusions on the ultrasonic action surface is increased to 48, and the shape of the micro-protrusions is changed to semi-cylindrical. The height of each micro-protrusion remains at 0.05mm, but the bottom width is increased to 0.25mm. The circumferential spacing between adjacent micro-protrusions is reduced to 0.15mm. This denser distribution of micro-protrusions increases the number of ultrasonic energy action points, resulting in a more uniform heat distribution at the welding interface. The width of the annular welding platform is adjusted to 2.5mm, and correspondingly, the width of the annular receiving platform is increased to 2.8mm. To accommodate the wider welding platform, the outer diameter of the ultrasonic energy transmission insert is increased to 40mm, and the wall thickness is increased to 2mm to provide more... With strong rigidity and energy conduction capabilities, the height of the inner guide boss has been adjusted to 0.4mm to ensure that the pressing limit is triggered only after the larger welding platform has completely melted. The outer diameter of the guide positioning part has been adjusted accordingly to 15.5mm, maintaining a 0.02mm interference fit with the positioning groove. In terms of welding process parameters, the amplitude has been increased to 60μm, the welding time has been extended to 1.5 seconds, and the pressing pressure has been increased to 0.4 MPa. Through these improvements, the welding strength has been increased to 96% of the base material strength. At the same time, due to the denser distribution of micro-protrusions and the optimized semi-cylindrical shape, the fluidity and filling effect of the molten material have been improved, and the appearance quality after welding has been further improved. Under a 10x magnifying glass, the weld interface still shows a smooth and continuous surface feature, making it suitable for structural connection parts that are subjected to large mechanical stress.

[0046] The following is another specific embodiment 3 of this utility model: This embodiment 3 is an optimization based on embodiment 1, targeting the need for seamless welding of transparent or light-colored plastic parts. Since transparent and light-colored materials are more sensitive to the appearance of welding marks, this embodiment adopts a more refined structural design. The width of the annular welding platform is reduced to 1.5mm, and the surface roughness is increased to Ra0.4 to obtain a smoother contact surface. A height difference of 0.15mm is set between the ultrasonic action surface and the annular welding platform, so that the ultrasonic action surface is slightly lower than the welding platform. This design allows the initial positioning and preheating to be mainly achieved by the contact between the annular welding platform and the receiving platform in the early stages of welding. When the material begins to soften, the micro-protrusions of the ultrasonic action surface gradually intervene to generate concentrated heating, avoiding premature strong friction that could lead to material degradation and discoloration. The height of the micro-protrusions is reduced to 0.03mm, and the number is reduced to 24, but a non-uniform distribution is adopted. The density of micro-protrusions is slightly higher in the four quadrants of the welding platform, while in other areas... The slightly lower density of the domain facilitates the directional flow of molten material and the removal of air bubbles during welding. The angle of the guide chamfer is optimized to 35°, and the radial extension length is increased to 0.7 mm, providing a smoother contact transition. The depth of the receiving space at the bottom of the positioning groove is increased to 6 mm, and three longitudinal venting grooves are added to the inner wall of the receiving space. Each venting groove is 0.3 mm wide and 0.2 mm deep to remove air trapped in the groove during the pressing process, preventing air bubbles from affecting the welding quality. The welding process parameters are set to an amplitude of 50 μm, a welding time of 1 second, and a pressing pressure of 0.3 MPa. A segmented pressurization method is adopted, with an initial pressure of 0.15 MPa for 0.3 seconds, which is then increased to 0.3 MPa. Through this progressive pressurization and optimized structural design, the appearance of the welded transparent part achieves a near-perfect, seamless effect. Even under strong light transmission, the weld interface is difficult to detect. The welding strength reaches 88% of the base material strength, meeting the high appearance requirements and basic strength requirements of transparent shell products.

[0047] Specifically, the principle of this utility model is as follows: The core principle of this structure lies in achieving precise and controllable seamless welding through the synergistic effect of geometric constraints and energy guidance. Firstly, in terms of spatial positioning, the positioning groove at the center of the lower pressing part forms a mating pair with the columnar guide positioning part. The interference fit between the outer circumferential surface of the guide positioning part and the inner wall of the groove ensures the coaxiality between the two. When the upper pressing part is pressed downward, the clearance fit between the inner diameter of the inner ring guide boss and the outer diameter of the guide positioning part forms a second layer of guiding constraint. This double-layer guiding mechanism fundamentally eliminates the radial interference that may occur during the pressing process. Offset and angular deflection ensure that the upper and lower pressing parts maintain a precise relative position. Regarding pressing depth control, a carefully designed height difference between the inner guide boss and the annular welding platform ensures that the contact between the top of the guide positioning part and the bottom surface of the guide boss always corresponds to the optimal welding state. At this point, sufficient ultrasonic energy transfer and material melting have been completed between the annular welding platform and the annular receiving platform. The limiting effect of the guide positioning part prevents further pressing movement, avoiding damage to the already formed weld layer due to excessive pressing. In terms of energy transmission, ultrasonic energy transmission... The insert is made of a metal material with good acoustic impedance matching. Its annular cross-section design allows ultrasonic energy to be evenly distributed circumferentially. The micro-protruding tooth structure distributed on the ultrasonic action surface at the bottom of the insert acts as an energy focuser. Under ultrasonic vibration, the tip of each micro-protruding tooth forms a local high-pressure contact area with the corresponding receiving platform, generating concentrated frictional heat in a very small contact area, causing the material to reach its melting point in a short time. The narrow annular welding platform confines the energy action area to the circumferential annular band. This highly concentrated energy characteristic allows the welding process to be completed quickly and reduces the diffusion range of the heat-affected zone. After welding, the molten material fills the original position of the micro-protruding tooth under pressure and completely fuses with the surrounding material to form a smooth transition interface. Due to the extremely small width of the welding area and the complete fusion of materials, no obvious welding marks are left on the appearance. Throughout the welding process, the self-centering function provided by the guide chamfer and the collection function of the bottom space of the positioning groove for collecting overflow further ensure the stability of the welding process and the appearance quality. Through the synergistic effect of this multi-mechanism, the technical goals of high-precision positioning, controllable pressing depth, and seamless welding appearance are achieved.

[0048] Before use, first insert the guide positioning component into the positioning groove in the center of the lower pressing component, ensuring a stable interference fit between the guide positioning component and the inner wall of the groove. Fix the lower pressing component on the lower tooling table of the ultrasonic welding equipment, ensuring its stable position using positioning pins or clamps. Check the installation status of the annular welding table surface of the upper pressing component and the ultrasonic energy transmission insert, confirming that the insert is firmly connected to the inner wall of the upper pressing component and that the ultrasonic action surface is clean and free of contamination. Install the upper pressing component under the welding head of the ultrasonic welding equipment, fixing it with the clamping mechanism of the welding head. Adjust the welding equipment parameters, setting the ultrasonic frequency, amplitude, welding time, and pressing pressure according to the plastic material. After starting the welding program, the ultrasonic welding head drives the upper pressing component downward. The inner ring guide boss first contacts the outer circumferential surface of the guide positioning component to form initial guidance. As the pressing continues, the annular welding table surface gradually approaches... When the distance between the ring-shaped receiving platform and the receiving platform approaches the set value, the ultrasonic generator begins to output vibration energy. The energy is transmitted to the ultrasonic action surface through the ultrasonic energy transmission insert. The micro-protruding tooth structure generates strong friction with the ring-shaped receiving platform under high-frequency vibration, quickly generating the heat required for welding. The plastic material begins to melt at the contact interface. At the same time, the pressing force is continuously applied, causing the molten material to flow and fill under pressure. When the spherical crown surface at the top of the guide positioning component is in complete contact with the bottom surface of the inner ring guide boss, the pressing motion automatically stops. At this time, the material at the welding interface has fully melted and formed a tight bond under pressure. After the ultrasonic output stops, the pressing state is maintained for several seconds to allow the molten material to cool and solidify. Finally, the welding head rises, completing one welding cycle. The welded component is removed for visual inspection and quality testing. The entire operation process does not require complex manual adjustments, the equipment has a high degree of automation, and the welding quality is stable and consistent.

Claims

1. An ultrasonic pressing structure using a seamless welding technique after injection molding, characterized in that, The device includes an upper pressing component, a lower pressing component, a guide positioning component, and an ultrasonic energy transmission insert. The bottom of the upper pressing component has an annular welding platform, which extends radially inward to form an inner guide boss. The top of the lower pressing component has an annular receiving platform that matches the annular welding platform. A positioning groove is formed at the center of the annular receiving platform. The guide positioning component has a columnar structure, and its outer circumferential surface is interference-fitted with the inner wall of the positioning groove. The ultrasonic energy transmission insert is embedded inside the annular welding platform of the upper pressing component. The bottom of the ultrasonic energy transmission insert forms an ultrasonic action surface, which is located on the same plane as or below the annular welding platform. The top of the guide positioning component contacts the bottom surface of the inner guide boss to limit the relative pressing depth between the upper and lower pressing components.

2. The ultrasonic pressing structure using a seamless welding technique after injection molding, as described in claim 1, is characterized in that... The outer wall surface of the upper pressing component and the outer wall surface of the lower pressing component form a continuous outer surface without step transition after pressing.

3. The ultrasonic pressing structure using a seamless welding technique after injection molding, as described in claim 2, is characterized in that... The height of the inner ring guide boss is higher than the height of the annular welding platform.

4. The ultrasonic pressing structure using a seamless welding technique after injection molding, as described in claim 3, is characterized in that... The ultrasonic energy transmission insert has an annular cross-sectional structure, and the outer circumferential sidewall of the ultrasonic energy transmission insert forms an interference fit connection with the inner wall of the upper pressing component.

5. The ultrasonic pressing structure using a seamless welding technique after injection molding, as described in claim 4, is characterized in that... The outer edge of the annular receiving platform is provided with a guide chamfer.

6. The ultrasonic pressing structure using a seamless welding technique after injection molding, as described in claim 5, is characterized in that... The depth of the positioning groove is greater than 1.2 to 1.8 times the length of the guide positioning part insertion portion, and the bottom of the positioning groove forms a receiving space to receive the overflow of molten material generated during the pressing process.

7. The ultrasonic pressing structure using a seamless welding technique after injection molding, as described in claim 6, is characterized in that... The ultrasonic action surface has multiple micro-protruding tooth structures evenly distributed.

8. The ultrasonic pressing structure using a seamless welding technique after injection molding, as described in claim 7, is characterized in that... Both the upper and lower pressing components are made of polycarbonate or acrylonitrile butadiene styrene copolymer, and the ultrasonic energy transmission insert is made of titanium alloy or aluminum alloy.

9. The ultrasonic pressing structure using a seamless welding technique after injection molding, as described in claim 8, is characterized in that... The guide positioning component is made of stainless steel, and the top surface of the guide positioning component forms a spherical crown structure, the radius of curvature of the spherical crown structure being 0.8 to 1.5 times the outer diameter of the guide positioning component.

10. The ultrasonic pressing structure using a seamless welding technique after injection molding, as described in claim 9, is characterized in that... The contact line width between the annular welding platform and the annular receiving platform in the pressed state is less than 0.5 mm.

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