Chinese name: ultrasonic welding mbth: working principle of ultrasonic welding: transmitting vibration waves to the welded surface: introducing mechanical movement, welding principle, welding type, welding method, welding advantages and disadvantages, and application prospect. Ultrasonic welding is to convert 50/60 Hz current into 15, 20, 30 or 40 KHz electric energy through an ultrasonic generator. The converted high-frequency electric energy is converted into mechanical motion with the same frequency again through the transducer, and then transmitted to the welding head through a set of horn devices. The welding head transfers the received vibration energy to the joint part of the workpiece to be welded, and in this area, the vibration energy is converted into heat energy through friction, thus melting the plastic. Ultrasonic can be used not only for welding hard thermoplastics, but also for processing fabrics and films. The main components of ultrasonic welding system include ultrasonic generator, transducer/horn/horn triplet, mold and frame. Linear vibration friction welding uses friction heat energy generated at the contact surfaces of two workpieces to be welded to melt plastic. Heat energy comes from the reciprocating motion of the workpiece on the other surface with a certain displacement or amplitude under a certain pressure. Once the expected welding degree is reached, the vibration will stop, and at the same time, a certain pressure will be exerted on the two workpieces, so that the newly welded part will cool and solidify, thus forming a close combination. Rail vibration friction welding is a welding method using friction heat energy. In the process of rail vibration friction welding, the upper workpiece moves on the rail at a fixed speed-making circular motion in all directions. This movement can generate heat energy, so that the welded parts of two plastic parts reach the melting point. Once the plastic begins to melt and the movement stops, the welded parts of the two workpieces will solidify and be firmly connected. The smaller clamping force will lead to the smallest deformation of the workpiece, and the workpiece with a diameter less than 10 inch can be welded by rail vibration friction. Welding principle Ultrasonic plastic welding principle When ultrasonic waves act on the contact surface of thermoplastic plastics, it will produce tens of thousands of high-frequency vibrations per second. This high-frequency vibration with a certain amplitude will transfer ultrasonic energy to the welding area through the upper weldment. Due to the large acoustic resistance in the welding area, that is, the interface between two welds, local high temperature will occur. Due to the poor thermal conductivity of plastics, they could not be distributed in time for a while and gathered in the welding area, which led to the rapid melting of two plastic contact surfaces and their integration after a certain pressure. When the ultrasonic wave stops, let the pressure last for a few seconds, so that it can solidify and form a solid molecular chain, thus achieving the purpose of welding, and the welding strength can be close to the strength of raw materials. The quality of ultrasonic plastic welding depends on the amplitude of the horn, the applied pressure and the welding time. The welding time and horn pressure can be adjusted, and the amplitude is determined by the transducer and horn. The interaction of these three quantities has a suitable value. When the energy exceeds an appropriate value, the melting amount of plastic is large, and the welded object is easy to deform. If the energy is small, it is not easy to weld firmly, and the external pressure should not be too large. This optimum pressure is the product of the side length of the welding part and the optimum pressure of every edge1mm. The ultrasonic metal welding principle of ultrasonic plastic welding machine is a special method to connect the same metal or different metals by using the mechanical vibration energy of ultrasonic frequency (above 16KHz). When the metal is ultrasonically welded, neither current nor high-temperature heat source is applied to the workpiece. Only under static pressure can the vibration energy of wire frame be converted into friction work, deformation energy and limited temperature rise between workpieces. Metallurgical bonding between joints is a kind of solid-state welding that does not melt the base metal, so it effectively overcomes the splash and oxidation caused by resistance welding. Ultrasonic metal welding machine can weld thin wires or sheets of non-ferrous metals such as copper, silver, aluminum and nickel by single point welding, multi-point welding and short strip welding. Can be widely used for silicon controlled lead wires. Welding type 1. Ultrasonic welding Ultrasonic welding of thermoplastics is a welding method in which two pieces of plastics are welded together under the action of ultrasonic vibration due to the heat generated by friction between molecules on the surface. Precautions for welding thermoplastics: A. The tenon and tenon design ensure convenient alignment in the welding cycle.
B the design of welding wire is slim, but there must be enough meltable material to melt the welding surface. The specific design method depends on what kind of workpiece equipment is used for welding. Parameters such as welding pressure and amplitude can be adjusted to ensure that the welding head can contact the welding surface and apply pressure. The lower workpiece is the pressure receiving part and is placed in the bottom die. The welding head generates high-frequency ultrasonic waves, which makes the upper workpiece generate thermal vibration, thus fusing with the lower workpiece. After the welding head stops vibrating, the pressure is maintained, and the melted part is cooled and formed. The whole welding time is mostly less than one second. 2. Ultrasonic metal welding Ultrasonic metal welding has the advantages of high speed, energy saving, high fusion strength, good conductivity, no spark and close to cold working; Disadvantages are that the welded metal part should not be too thick (generally less than or equal to 5mm), and the solder joint should not be too large, which requires pressure. Ultrasonic metal welding is a mechanical treatment process. During the welding process, there is no current flowing in the workpiece to be welded, and there is no welding arc such as welding mode. Because there are no problems such as heat conduction and resistivity in ultrasonic welding, it is undoubtedly an ideal metal welding equipment system for non-ferrous metal materials, which can effectively weld thin plates with different thicknesses. Application method of ultrasonic fusion welding by fusion welding 1. Fusion welding method: Under moderate pressure, the bonding surface of two pieces of plastic will generate friction heat with the ultrasonic ultra-high frequency vibration welding head, and instantly fuse and combine, and the welding strength can be comparable to that of the body. Through suitable workpiece and reasonable interface design, water tightness and air tightness can be realized, and the inconvenience caused by using auxiliary materials can be avoided, so as to realize efficient and clean welding. Second, riveting welding method: the ultrasonic ultra-high frequency vibration welding head is pressed on the protruding tip of the plastic product, so that it instantly heats up and melts into a rivet shape, so that materials of different materials are mechanically riveted together. 3. Embedding: With the preaching of the welding head and proper pressure, metal parts (such as nuts and screws) are instantly squeezed into the reserved plastic holes and fixed at a certain depth. The tension and torsion after completion can be comparable to the strength of traditional molding in the mold, which can avoid the defects of damage of injection mold and slow injection speed. 4. Forming: This method is similar to riveting. The concave welding head is pressed on the outer ring of plastic products. After the welding head vibrates at ultra-high frequency, the plastic melts and forms, and is fixed on metal objects, with smooth and beautiful appearance. This method is mostly used for the fixed molding of electronic products, speakers and cosmetic lenses. 5. Spot welding: A. Two pieces of plastic can be welded by spot welding without designing welding wires in advance. B. Spot-weld a large workpiece which is difficult to design the weld seam, so as to achieve the welding effect, and spot-weld multiple points at the same time. 6. Cutting and sealing: using the working principle of ultrasonic instantaneous vibration to cut the chemical fiber fabric has the advantages of smooth incision, no cracking and no drawing. Welding advantages 1, ultrasonic plastic welding advantages: fast welding speed, high welding strength and good sealing performance; Replacing the traditional welding/bonding process, it is low in cost, clean and pollution-free, and will not damage the workpiece; The welding process is stable, and all welding parameters can be tracked and monitored by the software system, which is convenient for troubleshooting and maintenance once faults are found. 2. Advantages of ultrasonic metal welding: 1), and the metal characteristics that the welding material is not melted and fragile. 2) After welding, the electrical conductivity is good, and the resistance coefficient is extremely low or close to zero. 3) The requirements for welding metal surfaces are low, and oxidation or electroplating welding can be adopted. 4) The welding time is short, and no flux, gas or solder is needed. 5), welding without sparks, environmental protection. Applicable products: 1), nickel-hydrogen battery, nickel mesh and nickel plate mutual melting, nickel plate mutual melting. 2) Copper foil and nickel sheet of lithium battery and polymer battery are fused with each other, and aluminum foil and aluminum sheet are fused with each other. 3) The wires are fused with each other, and one wire is partially fused with multiple wires. 4) The wires are fused with various electronic components, contacts and connectors. 5) The integration of large heat sinks, heat exchange fins and honeycomb cores of various household appliances and automobile supplies. 6), electromagnetic switch, fuse-free switch and other high-current contacts, dissimilar metal sheets melt each other. 7) Sealing and cutting metal pipes are waterproof and airtight. Disadvantages (1) When the thickness and hardness of the workpiece to be welded increase, the power required for welding increases exponentially, thus increasing the manufacturing cost of the ultrasonic welder. When the required power is too large, the design, manufacture and technological effect of acoustic system will produce a series of problems, so at present it is mainly limited to thin workpieces such as welding wires, foils and sheets. (2) At present, the joint form of ultrasonic welding system is limited to lap joint, and the workpiece can only extend within the size range allowed by the welding system due to the limitation of tool head, so the joint form and size range of welding are limited. (3) At present, ultrasonic welding quality inspection is very difficult, and general inspection methods are difficult to monitor in real time in the production process, and nondestructive inspection methods have not yet reached the popularization state. Application prospect For all application markets, ultrasonic welding has won recognition from all walks of life for its unique advantages-fast, efficient, clean and firm. Automobile: Ultrasonic wave can be controlled by computer program to weld large irregular workpieces, such as bumpers, front and rear doors, lamps and brake lights. With the development of high-grade highway, more and more reflectors are welded by ultrasonic wave. Ultrasonic metal welding machine (Wang Qiang Nico Ultrasonic) II. Household appliances: through proper adjustment, it can be used for portable fluorescent lamp cover, steam ironing door, TV shell, recording, transparent panel of radio, power rectifier, screw fixing seat of TV shell, mosquito repellent lamp shell, dehydration tank of washing machine and other household appliances that need to be sealed, firm and beautiful. Third, packaging: the sealing of hoses and the connection of special packaging belts. Toy industry: The adoption of ultrasonic technology makes products clean, efficient and firm, and eliminates the use of screws, adhesives, glue or other auxiliary products, thus reducing production costs and greatly improving the competitiveness of enterprises in the market. 5. Electronics: adopt automatic scheme design to enable users to realize large-scale production and ensure product quality requirements. Other commercial uses: He Ming ultrasound equipment can be used in communication equipment, computer industry, printing equipment and audio-visual products.