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1、热塑性塑料的焊接 by bj（Thermoplastic welding, by, bj）DOC documents may experience poor browsing on the WAP side. It is recommended that you first select TXT, or download the source file to the local view.1/10Thermoplastic weldingUsually think thermoplastic welding is not reversible. A few processes such as
2、induction welding can produce reversible assembly. To choose which method should be used in the design of parts made, because the welding requirement for product design may be important, and different welding methods with noticeable difference. 1. 2. 3. 4. 5. 6. 7. ultrasonic vibration welding weldi
3、ng rotary welding hot plate welding welding welding welding contact (resistance) of hot extrusion welding8. hot gas welding is used to weld plastic pipe, sheet or semi-finished products instead of injection molding parts. But many thermoplastic molding parts, especially thermoplastic automobile plat
4、e is used heat welding technology to repair, also sometimes used for the preparation of welding heat like plastic mouldings.Ultrasonic weldingThe most common method of welding of thermoplastic parts is ultrasonic welding. This method is the use of low amplitude, high frequency vibration energy (ultr
5、asound) and molecular surface friction welding pad plastic parts connected the required heat. (sinusoidal ultrasonic vibration) ultrasonic welding in the frequency range of 20-50kHz, the average amplitude range as low as 15kHz in 15-60um. (high amplitude) audio is sometimes used in larger parts or s
6、oft materials. The welding process usually occurs in 0.5-1.5s. The welding process even including welding time, welding position and welding pressure. Ultrasonic welding equipment is commonly used in the welding of the small size of the thermoplastic plastic parts, and a great the available parts of
7、 spot welding. The ultrasonic welding method according to the time of welding seam position (or collapse distance) or welding energy control. Also provide additional control of welding pressure and cooling time of ultrasonic welding. The equipment is generally not in the 20kHz is at the frequency of
8、 40kHz operation of the.20kHz device is more common. Joint design: the first is the most common type of joint, using ultrasonic vibration in the vertical direction is connected on the surface of the butt joint and Z joint. In this category, for most polymers. And the joint comprises a joint vibratio
9、n parallel to the surface second types of ultrasonic welding, formation of shear state. Various types of shear and embedded into second categories. The energy controller contact and amorphous materials together with the best, is shown in Figure 1 the energy controller node can be used in some large
10、closed half crystalline material.Reproduced: BJ2/10Butt jointBad butt joint design, welding time is too long, welding energy is too large, extrusion welding body lead to appearance defectsButt joint with energy oriented noiseThe butt joint is designed to shorten welding time, reduce welding energy,
11、and reduce extrusion overflow (visible)Additional material overflow collecting noiseReduced weld area, extruded melt, no finished product, no defect in appearanceZ shape jointImproved shear resistance helps components to locate the extruded melt without forming an appearance defectAll dimensions of
12、the /mm control energy of amorphous polymer h typical semi crystalline polymerA large part; a small part; a large partFigure 1The approximate size for all energy oriented amorphous and semi crystalline polymer.This is shown in the welded joint is on the joint design unique improved control of conven
13、tional energy. The following type with a rough or textured surface. To improve the welding quality will be improved, the ease of welding strength and welding work. There are many other texture shape is also feasible. Reprint: joint BJ3/10The overflow problem through the overflow groove is introduced
14、 in the design of pick off pollution and reduce, for safety, the general volume trough design spill over at least 10%. * press joint: in order to make the possibility of the formation of the minimum material overflow, pressure tight joints are designed to block or melt the melt remains in the meltin
15、g zone press joint semi crystalline. Plastic materials such as nylon is useful because the Commissioner structure is more complex and compact pick off required parts tolerances are relatively strict. Compared with the triangular energy oriented all welding, joint structures with large amplitude and
16、also need additional welding energy. Pressing the typical welding geometry figure 2.15 degree taperFigure 2 typical ultrasonic pressure welding structure parts without any measures to solve simple docking leveling leveling pieces mutually or on. More suitable for molding parts leveling pins or stud.
17、 The Z connection can automatic leveling, and when in use, the tensile resistance and improved in shear load and can eliminate the external. Overflow.Sliding clearanceOr 0.20-0.64mmOr 0.20-0.64mmFigure 3Typical Z open joint design for ultrasonic welding process(a) Z joints before welding: (b) welded
18、 Z - shaped joints: (c) improved Z - shaped joints: steps with shoulder covering the unevenness, resulting in improved appearance* groove tongue joint not only provides shear strength but also provides tensile strength. This joint is self centering. It is reproduced: BJ4/10The wall thickness of the
19、joint area must be relatively large to accommodate the tongue and groove joint design. In addition, the tolerances for the parts are relatively strict. The spacer reinforcement improves the leveling of the joints* shear connectorFigure 4 typical groove tongue joint design for ultrasonic welding proc
20、esses when welding semi crystalline polymers (or other difficult to weld polymers) and requiring sealingJoint number, is generally recommended to use shear. The need of high strength, high quality with the circular and rectangular parts Bei with shear joints. Shear joints with overlapping parts of t
21、he wall, when the joint is welded each other and are embedded, overlapping part tolerances and local shear. In order to promote the product leveling, including joint regulation part. In order to melt energy barrier on the side of the vertex in the initial contact surface is reduced. Because the melt
22、ing temperature of the material is consistent in the whole contact surface, parts are welded, two surface melt evenly. The depth is 1.0-2.0mm the use of 0.13-0.5mm within the range of tolerance. In order to prevent the external side in the welding process the tolerance caused by wall warpage, vertic
23、al parts should be shallow, but in the tongue and groove joint while the shearing improved can be used together with the tensile parts deep, provide The middle wall joint, which causes the side wall warpage due to tolerance, is minimized, as shown in Figure 5clearanceIntroduction of welding depthThr
24、eeFigure 5 typical ultrasonic welded shear joint design and typical mid wall shear joint designtoleranceTwoFour(a) parts before welding; (b) components after welding1- tongue and groove shear joints: help block inward bending; 2- support fixture: the purpose is to prevent the following components in
25、 the process of welding wall curved outward; above 3- components; 4- the following parts * slope slope joint engagement design can also provide high strength seal reproduced as amorphous and semi crystalline polymers: BJ5/10The joints are self fixed and are best suited for round or oval shapes of sm
26、all size. The welding energy of the ramp joint is very demanding. Figure 6. Typical use of ultrasonic welding in typical slope joint designComponent wallMinimum(a) slope joint; (b) improved slope joint (additional tolerance); 1- overflow trough; 2- clampJoint with 30 DEG -60 DEG slope angle and shou
27、ld be assembled in the plus or minus 1 degrees. The thickness of the melting zone to increase material added 0.10-0.25mm tolerances and produce weld overflow. When receiving overflow from the function or aesthetic is unable to use the collector. * with embedded seal welding with elastic embedding th
28、e sealing ring or toughness gasket also can obtain reliable sealing. As shown in Figure 7 is equipped with an elastic ring joint parts, so as to improve the ultrasonic welding joint can reach the sealing safety, welding or impossible to use in the case of continuous surrounding.Upper partFigure 7 ul
29、trasonic welded parts usually require sealing jointsBottom component1- energy guide; 2- elastic seal* electric welding, ultrasonic welding equipment can also produce electric plug welding and pin sleeve contact welding. In the application of no sealing joint, the pin sleeve joint can be used to conn
30、ect the same plastic materialGeneral ultrasonic pin socket / rivet welding jointPin / rivetInlet / pin (0.4-0.8mm) pin end or hole tipRadial tolerance(0.2-0.4mm)Figure 8 * ultrasonic weldingThe ultrasonic welding equipment can form a pin pass shear joint1- overflow collector; 2- before welding; afte
31、r 3- weldingThe variation of ultrasonic welding is ultrasonic welding. That is a thermoplastic parts fixed on another Reprint: BJ6/10Methods different material parts. The rivets or boss at the bottom should have very large radius or rounded, to prevent cracking or melting. In order to focus ultrasou
32、nd energy, the top boss should be designed with the welding head initial contact minimum. The boss at the top can be flat or conical, semi crystalline polymer filler or a conical is better. The integrity depends on the relationship between ultrasonic welding and rivet welding head accurate capacity.
33、Standard stakeAt stakeThe dome of the stakeHollow sectionFigure 9Ultrasonic welding or welding equipment can produce all kinds of structure1- = 1.6mm 2- trigger cone rivets; melting; 3- phi = 14.0mm rivet* standard 1.6-4.0mm in diameter welding between the rigid and flexible flat head rivet. The wea
34、r resistance of thermoplastic plastic is recommended to use the standard shape. * hemispherical welding glue is suitable. Less than 1.6mm diameter rivets suggested in hemispherical welding. On the wear resistance of plastic* overflow overflow type used in welding welding requirements for the applica
35、tion of surface flat or raised and lock channel parts thickness allowed. * hollow diameter greater than 4mm welding or rivet to the boss core can be blind boss. As shown in Figure 10 when the holes are not allowed to engage. When ultrasonic welding equipment can also form a mechanical interlock. Mol
36、ded plastic rivets (for welding and the like) and blind in the meshing parts chamfering can be formed with tolerance based (assuming with chamfer parts does not melt) true mechanical engagement.Different materialsMechanical interlockComplete engagementFigure 10 * material factors for ultrasonic weld
37、ingAn example of ultrasonic bonding that uses ultrasonic welding to form mechanical interlocks is suitable for most thermoplastic materials1- with softening and deformation of rivet thermoplastic parts; meshing component 2- with chamfer; 3- ultrasonic horn 1 amorphous polymers, especially amorphous
38、material at room temperature in the glassy state, usually weldingReproduced: BJ7/10A good candidate material. The glass state process of amorphous polymer with good performance by allowing transmission, see the near field and far field welding technology welding successfully. When the material is so
39、ft, is a problem on ultrasonic welding of amorphous material. Such as: high impact welding PS than general welding PS will generally require more energy and 2. Additional amplitude of semi crystalline polymers are generally more difficult to use ultrasonic energy increased by welding. The welding sy
40、stem emission energy values (i.e. increase amplitude); shorten the welding parts / contact surface and the distance between the joint interface; using near field of ultrasonic welding technology; welding head using amplitude up to 0.05-0.15mm. The high amplitude requires the use of titanium welding
41、the welding head. When the need of high strength, sealing assembly, shear joint and slope joint for semicrystalline polymers are applicable.3. Welding hygroscopic polymers: immediately welded after molding (when they are still dry); dry parts before welding; deposited in the dryer before weldingVibr
42、ation weldingVibration welding is friction welding process, welding parts which are under pressure to rub together until heat generated by friction and shear head scale surface to fully molten state. Once the molten film has been formed into the region to deep enough in 1999, the relative motion sto
43、ps, under the pressure of weld cooling and solidifying the vibration welding application. Almost all of the thermoplastic plastic one, reciprocating motion direction has allowed unconstrained movement of weld parts, medium or large parts. Material vibration welding and ultrasonic welding factors lik
44、e: amorphous materials than semi crystalline polymer is more suitable for welding by vibration. Similar ring vibration welding can weld size and welding connection to the distance from the rotation axis of approximately equal parts. The linear vibration welding in one direction to allow complete par
45、ts of linear vibration. When the joint is connected with the entire table When the surface is flat or slightly bent outside the plane, the vibration welding process is ideal for the partsRelative horizontal motionFrequency: 120240H Z. amplitude: (0.8 4 m m) pressureFigure 11 typical design for joint
46、 vibration welding (a) standards butt joint before welding; (b) standard butt joints after welding; welding equipment (c) with overflow groove butt joint of the 1- data collection improved; 2- single plane parting line; 3- welding joint with 4- overflow; overflow collectorReproduced: BJ8/10Rotary we
47、ldingRotary welding used to connect with rotational symmetric surfaces parts, it belongs to the friction welding process. Process is the most effective cylindrical thermal connection can be small or large plastic plastic parts. Often with peripheral vertical connecting plates feature assembly parts
48、with rotary welding technology. It is relatively to processing variables shear rate, welding pressure and welding time. Rotating welding joint strength depends on the material, joint design and use of the processing conditions; most thermoplastics can achieve strong seal weld. Rotary welding is not good for the transmission properties of materials especially suitable.As part of the wrench gusset feature provides a reliable torqueFig. 12 typical basic joint structure for rotary welding proces