热塑性塑料的焊接bjThermoplasticplasticweldingbj

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1、热塑性塑料的焊接 by bj（Thermoplastic plastic welding by bj）Doc documents may have a poor browsing experience at the WAP end. It is recommended that you choose TXT, or download the source file to the native view.1/10Welding of thermoplastic plasticThermoplastic welding is often thought to be irreversible. Fe

2、w can produce reversible process such as induction welding assembly parts. When it comes to choosing which method should be made at the beginning of the parts design, because the welding method on the design requirements of the product can be important, and different welding method with difference y

3、arrow. 1. 2. 3. 4. 5. 6. 7. Ultrasonic welding welding rotating vibration welding hot plate welding, induction welding contact welding welding hot extrusion welding (resistance)8. Plastic pipe welding technology is usually used to welding heat, or semi-finished products instead of plastic injection

4、molding parts. But many thermoplastic molding parts, especially thermoplastic car plate is made of hot air welding repair technology, another hot air welding is sometimes used for sample preparation of plastic molding.Ultrasonic weldingWelding is the most common method of ultrasonic welding of therm

5、oplastic parts. This method is to use low amplitude, high frequency rate (ultrasound) and molecular vibrational energy make surface friction heat required to produce plastic parts connected to the welding pad. (ultrasonic vibration is string) ultrasonic welding in 20 to 50 KHZ frequency range, the a

6、verage amplitude of the range of 15 to 60 um. 15 KHZ at low (high amplitude) of the audio is sometimes used for large parts or soft materials. Welding process usually happens within 0.5 1.5 s. Welding process male quantity including welding time, welding head position and welding stress. Ultrasonic

7、welding equipment is usually used to welding, the small size of the thermoplastic plastic parts, and a lot of multipoint welding parts available. Ultrasonic welding method can be according to the welding time and weld position distance (collapse) or welding energy control. Also provide additional co

8、ntrol of welding stress and cooling time. Is generally not in 20 KHZ ultrasonic welding equipment is running under 40 KHZ frequency. 20 KHZ device used more often. Joint design: the first kind is the most common type of joint, the connected vertically on the surface of the use of ultra sound vibrati

9、on. Docking and Z joint in this category, and is suitable for most of the polymer. The second type of ultrasonic welding joint including the vibration of the parallel to the joint surface, forming shear state. The various types of shear and scarf in the second category. Tao contact with amorphous ma

10、terials using optimal energy control, as shown in figure 1 tao and a larger energy control Can not confined in some semicrystalline materials in the application.Transfer: BJ2/10Butt jointPoor butt joint design welding time too long welding energy large extruded welding body causes appearance defectA

11、n energy-oriented docking jointThe welding time of the welded butt joint is designed to reduce the overflow of welding energy.Additional overflows collect noiseThe welding area reduces the appearance of the finished product without any defectZ jointThe improved shear resistance helps to locate the e

12、xtruder without forming a defectTypical energy control clamor for size/mm amorphous polymer h semi-crystalline polymerLarge parts with large parts for small partsFigure 1The approximate dimensions of the energy-oriented noise used in amorphous and semi-crystalline polymersAs shown in the figure of t

13、he welded joint is designed for the average energy control terminal unique improvements. The following type with a rough or texture of the surface to be improved. Will improve the quality of welding, welding and welding strength to complete ease. Many other striped joint appearance are also possible

14、. Reprint: BJ3/10Material overflow problem through introduce the material overflow tank pollution after the pass design and reduce, for safety, generally the material overflow slot at least 10% of the excessive volume capacity. * compression joint: in order to make the material overflow least likely

15、 formation, is the purpose of the compression joint design block fuse body or will melt in the fusion zone. The compression joint half-and-half crystallization of plastic material such as nylon is useful. Because close structure more complicated, tightly shut the required pressure parts fit toleranc

16、e is relatively strict. Compared with the triangle energy guide tao welding joint, larger amplitude and welding joint structure also need additional energy. A typical welding geometry compression As shown in figure 2.15 taperFigure 2 typical ultrasonic press stamping leveling simple butt welded stru

17、cture without any measures to solve the parts in a leveling or each other. Stamping leveling is more suitable for use molding positioning pin or double screw. The z can automatic leveling, and when use tensile and changed into make shear load resistance. And can eliminate the external material overf

18、low.Slide clearanceOr 0.20 0.64 mmOr 0.20 0.64 mmFigure 3Typical z open joint design for ultrasonic welding process(a) z joint before welding: (b) the z-connector after welding: (c) improved z joint: the shoulder of the steps is covered with shoulder cover, resulting in appearance improvement* slot

19、tongue joint not only provides shear strength but also provides tensile strength. This joint is self - correct and reprinted: BJ4/10The wall thickness of the joint area must be relatively large for the joint design of the groove tongue. In addition, the tolerances of the making parts are relatively

20、strict.* shear subFIG. 4 a typical grooved tongue joint design for ultrasonic welding is used to weld a semi-crystalline polymer (or other hard-to-weld polymer) and need to be sealedPick up top, generally recommended to use shear joint. Need high strength, high quality meet Bei circular and rectangu

21、lar parts are with shear joint. Shear joint top with overlapping part wall parts, when the joint is welding and each in turn embedded, overlapping part of tolerance and local shear. In order to promote stamping leveling, joint includes adjusting part. In order to centralized fusion energy, the block

22、age on the side of apex Angle on the initial contact. Because the temperature of the melt material in the contact surface consistent parts are welded, two surface melt even. The use of a depth of 1.0 2.0 mm tolerance values within the scope of 0.13 to 0.5 mm. In order to prevent due to poor and in t

23、he process of welding and the external wall buckling, vertical parts should be as light as possible, but on one side with shear improved rabbet joint parts can be used together with the deep drawing parts, provide the wall connection, it makes the result of the tolerance of wall buckling minimum. As

24、 shown in figure 5.clearanceWeld penetration3Figure 5 typical ultrasonic welding shear connector and typical wall assembly shear joint designThe tolerance24(a) pre-welding parts; (b) the parts after welding1 - slot tongue shear connector: helps prevent the parts from bending inward; 2 - support jig:

25、 the purpose is to prevent the following parts wall from bending outward during welding. 3 - the parts above; 4 - the slope joint ramp joint design can also provide high strength sealing for amorphous and semi-crystalline polymers: BJ5/10Joints. Slope joints are self-fixed and most suitable for smal

26、l round or elliptical shapes. The welding energy requirements of the ramp joints are very high. Figure 6 is a typical slope joint design for ultrasonic weldingPart wallThe minimum(a) slope joint; (b) improved slope joints (with tolerances) 1 - overflow tank; 2 - clampSlope joint with 30 to 60 Angle

27、and should be within + / - 1 assembly. As an additional investment area increased 0.10 0.25 mm material thickness tolerance of weld and flash. When cant accept material overflow from the function or aesthetic, use the collector. * with embedded seal welding with embedded elastic sealing ring or toug

28、hness gasket also can obtain reliable seal. As shown in figure 7 joint is equipped with an elastic ring parts, to improve the use of ultrasonic welding joint can reach seal security, or in the periphery of continuous welding is not possible use.Upper part of upper partFigure 7. Ultrasonic welds usua

29、lly require close connectionsThe underlying parts of the underlying parts1 - energy guide; 2-elastic seal* electrobolted ultrasonic welding equipment can also produce electric plug and pin sleeve contact welding. In applications that do not require seal grafting, pin sleeve joints can be used to con

30、nect the same plastic materials.General ultrasonic pin hole/riveting jointPin/rivetingImport/fixed hole (0.4-0.8 mm) pin end or hole tipThe radial tolerance(0.2 0.4 mm)Figure 8 * ultrasonic riveting weldingThe ultrasonic welding equipment can form the pin hole shear joint1 - overflow collector; 2 -

31、before welding; 3 - after weldingThe variation of ultrasonic welding is the ultrasonic riveting welding6/10Methods on the parts of different materials. Rivets or convex platform there should be a very big radius at the bottom or rounded corners, to prevent cracking or melting. In order to focus ultr

32、asonic energy, convex platform should be designed and welded at the top of the head of the initial contact with the most small. The top can be either flat or convex conical, half crystallization or filled polymer with conical better. The integrity of the ultrasonic welding depends on accurate capaci

33、ty of relationship between riveting and welding head.Standard plugHard pegDome pegThe hollow plugFigure 9.Ultrasonic welding equipment can produce riveting or various structures1 - rivet of phi greater than or equal to 1.6mm; 2 - taper trigger melting; 3 - phi acuity 14.0 mm rivet* standard maohan 1

34、.6 4.0 mm in diameter of the flat head rivets. Do not wear resistant thermoplastic of rigid and flexible plastic is recommended to use standard shape. * hemispherical maohan glue is appropriate. Suggestions with diameter less than 1.6 mm rivet on the hemispherical maohan. For wear resistant plastic*

35、 overflow maohan overflow maohan used in requirements for flat surface or the thick degree of uplift and lock the letter be allowed to use the application. * hollow maohan Convex platform or larger than 4 mm in diameter rivet to core can be born blind hole convex platform. As shown in figure 10 Mesh

36、 when parts are not allowed to have a hole in the ultrasonic welding equipment can also form a mechanical interlock. Molded plastic rivets (similar to the one that is used to weld) and blind chamfering in the mesh parts can be formed on the basis of the difference of male (assuming with chamfer part

37、s dont melt) of real mechanical joint.Different materialsMechanical interlockFinished jointFigure 10. Material factors for ultrasonic weldingThe example ultrasonic welding with ultrasonic welding is suitable for most thermoplastic materials.1 - thermoplastic components with softening and deformation

38、 rivets; 2 - engaging meshing parts with chamfering; 3 - ultrasonic welding head 1 amorphous polymer, especially at room temperature outside the glassy amorphous substance, usually weldingTransfer: BJ7/10Process good candidate materials. Glass state amorphous polymer with good transmission performan

39、ce, allowed Allowable see near and far field welding technology welding success. When the material is soft, shaped material ultrasonic welding is a problem. Such as: welding high impact ps will need much more energy than welding general ps general and additional amplitude. 2 semicrystalline polymers

40、 generally more difficult to use ultrasonic welding energy. Increase by welding the launch of the energy system (that is, the increase amplitude); Shortening the distance between the contact surface and the interface between the welding head/making contact surface; To make use of near-field ultrason

41、ic welding technology; Use the welding head with the amplitude of 0.05-0.15mm. The high welding amplitude requires the use of titanium welding head. When high strength and seal assembly are required, the shear joint and the inclined slope are used for the semi-crystalline polymer.3. Welding and hygr

42、oscopic polymers: welding parts immediately after molding (when they are still dry); Dry parts before welding; Store the parts in the dryer before welding.Vibration weldingVibration friction welding is a welding process, during which the welding parts rub together under pressure until the heat gener

43、ated by friction and shear to head the pest surface fully molten state. Once the molten film has formed into deep enough for improving area, relative motion stops, the weld cooling and solidification under pressure. Vibration welding for almost all of the thermoplastic friends to plastic, reciprocat

44、ing motion direction has allowed unconstrained moving weld parts, medium or large parts. The vibration welding material factor and the ultrasonic welding similar: amorphous material than semicrystalline polymer is more suitable for mining Use of vibration welding similar. Circular vibration welding

45、welding area size and welding area can connect to the axis of rotation at a distance of approximately equal parts. Linear vibration welding In allowing a direction linear vibration on complete parts. Connector When the connection is the entire surface of the flat or slightly to the out-of-plane bend

46、ing, vibration welding art is the most ideal for parts.Relative horizontal motionFrequency rate: 120 240H z. Vibration amplitude: (0. 8 4.0 m m) pressureFIG. 11 standard butt joint for vibration welding with typical joint design (a); (b) standard butt joint after welding; (c) use overflow material t

47、o collect improved docking joints 1 - soldering equipment groove;2 - flat surface parting line; 3 - welding overflow; 4 - joint with overflow collectorTransfer: BJ8/10Spin weldingRotating welding used to connect with rotational symmetry parts of the joint surface, it belongs to the friction welding

48、process. Even meet but can small cylindrical thermoplastic plastic stamping the most effective process. Assembled from rotating welding technology system always has such characters as connected to the surrounding the vertical plate. It to processing variables is relative shear rate, the welding stre

49、ss and welding time. Spin welding joint strength depends on the material, joint design and the processing conditions; Most thermoplastic plastic can achieve strong gas seal weld. Rotary welding is especially suitable for materials with poor transmission performance.The component features of the Angl

50、e brace provide reliable torqueFIG. 12 typical basic joint structure for rotating welding process 1 - butt joint; 2 - groove tongue joint; 3 - the T of the collector, G joint 4-slope joint; 5 - shear jointElectromagnetic weldingElectromagnetic welding, induction welding) is used to reach the melting

51、 temperature of inductance energy connection method is also called the special insert welding of thermoplastic parts Here magneto optical aggregation insert heated by a high frequency electromagnetic field., the welding material is generally magneto optical filled polymers, it is made on the materia

52、l and product made in the same polymer or incompatible polymer. This kind of strong magnetic filled polymers including fine dispersed, micron sized iron grain, iron oxide particles, particles of stainless steel or other magnetic materials, they become the target of electromagnetic energy. According

53、to the volume calculation of the amount of strong magnetic powder loading is less than 15% when the force on the parts on the welding joint shear, the most solid weld. Practice is the most commonly used joint rabbet joint and Z. Induction welding needs to have additional costs to make use of embedde

54、d welding material, and is not suitable for parts reproduced with sensitive electromagnetic parts: BJ9/10If used together with metal.Figure 13 typical joint structure (a) (a) (b) (c) (c) (d) of the electromagnetic welding (c) (c) (d), the joint of the groove groove joint and the cut joint of the gro

55、oved joint of the grooved jointContact (resistance) weldingContact resistance welding electrical wires or stripe is directly into the joint interface, wires and electrical resistance in the circuit loss directly heated. Passed to the adjacent heat by thermal conductivity of plastic material, plastic

56、 solid soften or melt in local area. Therefore, when the power is welding area or cooling, pressure make the mesh parts touch each other. The minimum equipment requirements, welding process simple and fast, especially suitable for welding large parts. But need to loss heating electrical wire, weldin

57、g wire remain in situ after, increase the processing cost, and the existence of the wires and weld strength degree have an adverse impact on finished product.Hot plate weldingHot plate welding (flat) parts, it is electric heating metal mold is attached plastic parts surface soft thermoplastic weldin

58、g process. Apply to almost all the big or small thermoplastic parts. Especially suitable for welding with a softer semicrystalline thermoplastic plastics such as PE or PP. Due to the mold surface temperature in the different name applied to two different kinds of thermoplastic materials, it is the m

59、ost suitable for welding of different materials. Hot plate welding can achieve very high welding strength.However, the cycle of this process may be relatively long. Small parts require 15s, while large parts take a few minutes.The heat of weldingHot air welding is widely used in connecting the therm

60、oplastic material and sheet production large parts of the welding methods. Is suitable for the need for local assembly of smaller injection molding parts, repair and sample molding of thermoplastic parts of manufacturing. With the reprint: BJ10/10It is important to make welding rods for the same pol

61、ymer brands as welding partsExtrusion weldingExtrusion welding is a welding process developed by hot gas welding.adhesiveAdhesive polymer can be used to connect to the same raw material of plastic parts, are commonly used to butt system made of different material parts. The thermosetting plastic par

62、ts are connected, or make connection. Plastic parts and metal binder optimal points include:Beautiful, flexible design; Uniform stress distribution; Able to connect different materials; Able to provide a tight seal of air/water/gas; Soft adhesive can buffer vibration; Can be used with thin and soft

63、base material; Provide electrical insulation and thermal insulation.Limitations of adhesives:The performance of the joint is not qualitative; Permanent assembly; Comprehensive chemical process; Need clean surfaces; No joint detection; Time of maximum intensity.Binder selection choice depends on the

64、specific application of binder factors include using environment, stress value of base material surface, substrate rigidity characteristics, base material thermal expansion coefficient, caulking requirements and application method.Solvent adhesiveSolvent adhesive can be assembled some of the thermoplastic parts, the method of the most commonly used amorphous thermoplastic plastic pieces. Solvent adhesive are formed strong amorphous thermoplastic parts seal assembly of simple, relatively inexpensive method. Low viscosity of the solvent by bonding parts should be no bending an