Introduction and Principle
Ultrasonic welding is a high-tech technology for welding thermoplastic products, and various plastic parts can be used for ultrasonic welding, without having to solute, adhesive Or other auxiliary products. Ultrasonic welding is a novelty of secondary processing technology, which has developed with its efficient, high quality, beautiful, energy-saving advantages. Survival welding products have brought great convenience to production and life, which is widely used in automotive, electrical appliances, medical, toys and other industries. Many products are ultrasonic welding, such as audio systems such as TV.
The advantage is to increase multiple productivity, reduce cost, improve product quality and safe production. The ultrasonic energy is transmitted to the welding area by the upper solder, and the acoustic impedance is large due to the two welded interfaces, thereby producing a local high temperature. In addition, due to the poor thermal conductivity, it is still not possible to distribute in time, gather in the weld area, resulting in rapid melting of the contact surface of the two plastics, plus a certain pressure, making it integral. When the ultrasonic waves stopped, the pressure lasts for a few seconds, so that it is solidified, so that a rugged molecular chain is formed, and the purpose of welding, the welding strength is close to the raw material strength.
Ultrasonic welding It is usually used in plastic welding, which is completely instead of the traditional industry bonded to glue, and is no bolt, nail, snap, welding material or adhesive during ultrasonic welding. When the material is combined, it is faster than the conventional binder or viscose water, while the drying time is very fast, the welding process can be easily realized, easy to customize, to accommodate various types of specific specifications The product is welded.
1, welding method:
The joint surface of two plastic joints is made under moderate pressure at moderate pressure, the welding head of ultrasonic ultra high frequency vibration In an instant melt joining, the welding strength can be comparable to the body, and the appropriate workpiece and reasonable interface design can be reached, and the inconvenience caused by the auxiliary product is exempted to achieve high efficiency cleaning.
two, riveting method:
Press the tip of the ultrasonic ultra high frequency vibrating, pressed the tip of the plastic product, so that it instantly heats into a rivet shape, so that different Material mechanical riveting together.
By the passage of the weld head and appropriate pressure, the metal parts (such as nuts, screws, etc.) are extruded into the plastic hole, Fixed in a certain depth, no matter the strength, torque, which is comparable to the intensity of the shape of the traditional mold, can be avoided and the shortcomings of the injection molding and slowness.
This method is similar to the riveting method, and the concave weld head is pressed against the outer ring of the plastic product, and the solder head will be used to emit ultrasonic ultra-high frequency vibration. Plastic solute is covered with metal objects to fix it, and the outer view is slightly used, and this method is used mostly in the electron, the fixed formation of the horn, and the mirror fixation of the cosmetic class.
five, spot welding:
a, the two plastic points are welded without pre-designing the wire, and the purpose of welding is achieved.
b, the workpiece of compared large workpieces, not easy to design the welding wire, and reach the welding effect, and can be soldered more simultaneously.
six, cutting sealing:
Using ultrasonic instantaneous vibration-in-vibration working principle, cutting the chemical fiber fabric, its advantageous incision is not cracking, non-brushed.
Ultrasonic welding technology requirements
The effect of ultrasonic welding depends on many factors, such as plastic type, product shape (geometric shape, wall thickness, etc.), welding requirements (i.e., viscosity, Strength, seal, etc.).
The plastic parts of the ultrasonic welding process must pay attention to the shape of the surface, the direction of conduct, the transfer, the direction of the energy point, the widening of the profit, and the variety of thermoplastics, The characteristics are different, and the use of the use is very different, so the plastic parts should consider the process requirements of supersonic welding when designing.
The design of the welding head in the ultrasonic welding machine is critical, and only the resonant state can be welded to the satisfactory product, and the sound wave generator can stabilize.
The problem and solution encountered during ultrasonic welding
The strength cannot achieve the desire standard
1. The same melting point plastic welding strength is stronger. 2. The gap between the plastic material melting point is larger, the smaller the welding strength. 3. The higher the density of the plastic material (hard) is high than the lower slender (toughness of toughness).
Product surface generates scars or cracks
In the supersonic welding operation, the surface of the product produces scars, and the binding or cleavage is common. Because two situations are generated in ultrasonic operations: 1. High heat energy direct contact with plastic product surface 2. Vibration conduction.
So the ultrasonic hair is actuated in the plastic product, the surface of the product is prone to burns, and the thick plastic column or holes within 1mm, which is also easy to create rupture, this is ultrasonic operation The phenomenon is unavoidable. On the other hand, there is a long period of time to fill the output power when the vibration friction energy is transferred to thermal energy, to accumulate thermal energy to compensate for insufficient output power. Such a welding method is not the vibration friction thermal energy achieved in an instant, while the fusion time is required to accumulate thermal energy, and the melting point of the plastic product reaches the melting effect, which will cause heat to stay in the surface of the product, and the cumulative temperature With pressure will also cause burns, shock or rupture of the product. This must be considered at this time, and the function of the power output (segment), the fusion time, dynamic pressure, etc. must be considered to overcome the lack of this job.
Solution: 1. Reduce the pressure. 2. Reduce delay time (early yield)). 3. Reduce the fusion time. 4. Reference media coverage (such as PE bag). 5. Improve surface treatment (hardening or chrome plating). 6. The number of machine segments is reduced or reduced to the upper mold expansion ratio. 7. Easy to shock or discharge products, fixture should be made into buffers, such as a soft resin or a cork, etc. (this indicator does not affect the welding strength). 8. Easy to break the R angle at right angles.
Products Generate Twisted Deformation
This deformation happens that it has three: 1. The body and the angle or the curved angle or the arc cannot be honest; 2. Product meat Thickness (within 2 mm) and the length is more than 60 mm or more; 3. The product is distorted by the condition of injection molding pressure.
Solution: 1. Reduce the pressure (preferably below 2kg). 2. Reduce ultrasonic welding time (reducing strength standard). 3. Increase the hardening time (at least 0.8 seconds). 4. Analyze whether the ultrasonic upper and lower molds can be partially adjusted (if necessary). 5. Analyze the deformation of the product, improve it.
Product internal parts damage
After supersonic welding, the product destruction is as follows: 1. Ultrasonic welding machine power output is too strong; 2. Ultrasonic energy expander energy output is too strong ; 3. The bottom mold is suspended, and it is damaged by ultrasonic conduction vibration; 4. The plastic product is high, the bottom right angle of the bottom, and the R angle of the coercive energy is not set; 5. Incorrect ultrasonic processing conditions ; 6. The post or fragile part of the plastic product is opened in the plastic mode.
Solution: 1. Early micro-vibration time (avoid contact vibration). 2. Reduce pressure and reduce ultrasonic welding time (reducing strength standard). 3. Reduce the number of machine power segments or small power machines. 4. Reduce the expansion ratio of ultrasonic molds. 5. Bottom power is a buffer rubber. 6. The bottom mold and the product are avoided from floating or gaps. 7.Horn (upper mold) The frequency is retransmitted after the hole. 8. Adhesive elastic materials after the upper mold.
Products produce overflow or burr
Ultrasonic welding After the product, the product has the following: 1. Ultrasonic power is too strong; 2. The ultrasonic welding time is too long; 3. Air pressure (dynamic) is too large; 4. Under the upper mold pressure (static) is too large; 5. HORN energy expansion ratio is too large; 6. Plastic products are molf wire too late or too high or thick.
Solution: 1. Reduce the pressure and reduce the supersonic welding time (reducing strength standard). 2. Reduce the number of machine power segments or small power machines. 3. Reduce the expansion of ultrasonic molds. 4. Use ultrasonic machine fine-tuning positioning. 5. Modify the ultravailability of the ultrasonic wave.
Product welding After the size is unable to control
in the ultrasonic welding operation, the product cannot be controlled to the tolerance range has the following reasons: 1. Machine stability (energy Conversion does not add security factor); 2. Plastic product deformation exceeds ultrasonic natural fusion range; 3. Tuition or endurance is unstable; 4. Ultrasonic upper module energy expansion output does not cooperate; 5. Fusion processing conditions have not been added Safety factor.
Solution: 1. Increase the welding safety factor (sequentially, the fusion time, pressure, power). 2. Enable the fine-tuning fixed screw (should be controlled to 0.02 mm). 3. Check if the output energy of the ultrasonic upper mold output is sufficient (not enough to increase the number of segments). 4. Check if the potential positioning and product receiving power is stable. 5. Modify the ultravailability of the ultrasonic wave.
Ultrasonic welding is commonly used in the automotive industry, electronics industry, medical industry, home appliance industry, non-woven garment, office supplies, packaging industry, toy industry, etc. Such as body plastic parts, car doors, car car instruments, lights lambling, sun visor, interior parts, filter, reflective materials, anti-light path nails, bumpers, cable, motorcycle plastic filter, heat dissipation Machine, brake liquid tank, oil cup, water tank, fuel tank, duct, exhaust gas purifier, pallet filter board; plastic electronics: prepaid water meters, communication equipment, cordless telephone, mobile phone accessories, mobile phone case, battery case, charger , Valve controlled sealed maintenance lead-acid battery, 3-inch floppy disk, U disk, SD card, CF card, USB connector, Bluetooth; toy stationery: folder, album, fold box, PP hollow board, penket, ink cartridge, toner cartridge, Medical daily: watch, kitchenware, oral liquid bottle cover, point droplet cap, mobile phone ornaments, Jin Port, daily necessities, hygiene products, children's products, air mattresses, hangers, knives, gardening, ware, Shower, gold prosthetic brush, shower head, anti-counterfeiting bottle cover, cosmetic cap, coffee maker, washing machine, air dehumidifier, electric iron, electric kettle, vacuum cleaner, speaker metal cover and earth grill, etc.