We do the welding machine independently
Many designs in life (in the garage, at the dacha, houses, etc.) it is difficult to construct without welding application, in particular arc. Now on counters of shops the large number of electrowelding machines of both the import, and USAn proyoizvodstvo appeared. Good devices stand дорого, and cheaper not always obespechiyovat quality of welding works. In the offered article it would be desirable to share some reasons of generally practical character on designing of amateur svarochyony devices (S.A.) on the osnoveanaliz of earlier opublikoyovanny
materials. It will help not только with independent production of amateur S.A., but also at the choice and the poyokupka of already ready welding machines.
Welding machines happen postoyanyony and alternating-current.
S.A. of the direct current are used when welding on small currents of tonkolistoyovy metal (roofing steel, avtomoyobilny, etc.). The welding arch on postoyoyanny current is steadier, possible welding on direct and the return polyarnosyota. On the direct current it is possible to cook the electrode wire without plastering and the electrodes intended for welding both on the direct current, and on variable. For giving of stability of burning of the arch on small currents it is desirable to have the increased tension of no-load operation of Uxxsvarochnoy of the winding (to 70 - 75 V). For alternating-current straightening the simplest "bridge" rectifiers on powerful diodes with radiyoator of cooling (fig. 1) are used.
For smoothing of pulsations the napryazheyoniya one of conclusions of S.A. A is connected to the holder of electrodes through L1 throttle representing the coil from 10 - 15 rounds of the copper tire section S = 35 mm2 who is reeled up on any serdechyonik, for example, from the magnetic actuator. For straightening and the smooth reguliyorovaniye of the welding current more compound circuits with use of the powerful managed thyristors are used. One of possible schemes on thyristors of the T161 (T160) type is given in A. Chernov's article "Both will load and will weld" (the Modeller-designer, 1994, No. 9). Advantages of reyogulyator of the direct current — in their uniyoversalnost. Range of change of tension by them is 0,1-0,9 Uxx that allows to use them not only for Yoplavny adjustment of current of welding, but also for charging of rechargeable batteries, the power supply of electric heating elements and other purposes.
Fig. 1. The bridge rectifier for the welding machine. S.A. connection for the svaryoka of thin-sheet metal on the "return" poyolyarnost — "+" on the electrode, "-" on the svariyovayemy part of U2 is shown: — output variable nayopryazheniye of the welding machine
Alternating-current welding machines are used when welding the elektrodayoma which diameter more than 1,6 - 2 mm, and thickness of the welded products — more than 1,5 mm. At the same time current of welding is considerable (tens of amperes) and the arch burns rather steadily. The electrodes intended for welding only on alternating current are used. It is necessary for normal operation of the welding machine:
- To provide voltage output for reliable ignition of the arch. For lyuyobitelsky S.A. Uxx = 60 - 65 century. More vyyosoky voltage output of no-load operation is not recommended that is connected in osyonovny with safety of the rayobota (Uxxpromyshlennykh of welding apyoparat — up to 70 - 75 V).
- To provide tension of welding of Usv necessary for steady burning of the arch. Depending on diameter electrofood - Usv of =18 - 24 century.
- To provide rated svarochyony current of Isv = (30 - 40) de where Isv — the veliyochina of the welding current, And; 30 - 40 — коэффициент, depending on type and diameter of the electrode; de — diameter of the electrode, mm.
- To limit current short the zamykayoniya of Ikz which size should not preyovyshat the rated welding current more than for 30 - 35%.
Steady burning of the arch is possible if the welding machine will possess falling external harakterisyotiky which defines dependence between the current intensity and tension in the svayorochny chain (fig. 2).
S.A. shows that switching of both peryovichny windings, and secondary is necessary for rough (stupenyochaty) overlapping of range of welding currents (that is structurally more difficult because of the bolyyoshy current proceeding in it). Besides, for smooth change of current of welding within the chosen range mechanical devices of the peremeyoshcheniye of windings are used. During removal of the welding winding rather network magnetic fluxes of dispersion uvelichiyovatsya that leads to decrease in current of welding.
Designing amateur S.A., it is not necessary to aim to full the perekryyotiya of range of welding currents. At the first stage to assemble by Tselesoyoobrazno the svarochyony device for work with electrodes with a diameter of 2 - 4 mm, and at the second stage, in case of need works on small currents of welding, to add it with the separate vypryamitelny device with smooth regulation of the welding current. Amateur welding machines have to meet to the number of requirements, the basic of which following: otnoyositelny compactness and small weight; sufficient period of operation (not less than 5 - 7 electrodes of de = 3 - 4 mm) from network 220v.
The weight and dimensions of the device can be reduced thanks to the umensheyoniya of its power, and increase in the prodolyozhitelnost of work — thanks to the steel ispolyyozovaniye with the high magnetic proyonitsayemost and heatpermanent isolation of winding wires. It is simple to fulfill these requirements, knowing bases of the konyostruirovaniye of welding machines and придерживаясь the offered technology of their production.
Fig. 2. The falling external characteristic of the welding machine: 1 — family характеристик for different ranges of welding; Isv2, Isvz, Isv4 — ranges of currents of welding for electrodes with a diameter of 2, 3 and 4 mm sootvetstyovenno; Uxx — tension of no-load operation of SA. Ikz - the short-circuit current; Ucv - the welding voltage range (18 - 24 V).
Fig. 3. C type magnetic circuit: and — plates of the G-shaped form; — plates of the P-shaped form; in — plates from strips of transformer steel; S = — the cross-sectional area of the core (core), cm2 with, d — the window sizes, see.
So, the choice like the core. For production of welding apparayot use generally c type magnetic circuits as in the isyopolneniye they are more technological. Seryodechnik gather from the plates of elektrotekhyonichesky steel of any configuration tolyoshchiny 0,35 - 0,55 mm which are pulled together with the shpilyyoka isolated from the core (fig. 3). At selection of the core необходимо to consider the sizes of "window" that windings of the welding apparayot, and the cross-sectional area of the seryodechnik (core) of S =axb, cm2 were located. As practice pokayozyvat, it is not necessary to choose miyonimalny values S = 25 - 35 cm, the welding machine will not obyoladat the poyoskolka the required stock of power and will trudyono be to receive high-quality welding. And overheating of the welding machine after short work is also inevitable.
Section of the core has to составлять to S = 45 - 55 cm2. The welding machine will be slightly heavier, but will not bring! The increasing distribution is poluchayot by amateur welding machines on cores of toroidal type which possess higher elektrotekhniyochesky characteristics, is about 4 - 5 times higher, than at rod, and electrolosses are small. Labor costs on their production are more considerable also svyayozana first of all with placement of windings at the torus and complexity of the nayomotka.
However at the correct approach they yield good results. Serdechniyoki is produced from the tape transforyomatorny iron rolled in the form of the torus. The core from the Latr autotransformer on 9 A can be the example. For increase in the internal diayometr of the torus ("window") from the inside wind off the part of the steel tape and nayomatyvat on outer side of the serdechyonik. But, as practice shows, one-its Latra is not enough for qualitative S.A. production (few section S). Even after work with 1 - 2 electrodes of diametyory 3 mm it overheats. Perhaps isyopolzovany two similar cores according to the scheme described in B. Sokolov's article "The welding kid" (1993, No. 1), or production of one core by rewind of two (fig. 4).
Fig. 4. Magnetic conductor of toroidal type: 1.2 - the autotransformer core before rewind; The 3rd design of S.A. on the basis of two toroidal cores; W11W12 — the network windings included in parallel; W2 — the welding winding; S = — the cross-sectional area of the core, cm2, with, d — internal and external diameters of the torus, cm; 4 — the circuitry of S.A. on the basis of two soyostykovanny toroidal cores.
The special attention is deserved by the lyubiyotelsky S.A. made on the basis of stayotor of asynchronous three-phase elektroyodvigatel of big power (more than 10 kW). The choice of the core is defined by stator S cross-sectional area. Stamped plates of the stator not fully correspond to parameters of electrotechnical transformer steel therefore it is inexpedient to reduce section S less than 40 - 45 cm.
The stator is exempted from the body, stator obyomotka udayolyat from internal grooves, cut down the chisel of the crossing point of grooves, protect the internal poverkhyonost the file or the abrasive kruyog, round sharp edges of the serdechniyok and wind it densely, with perekryyotiy the cotton insulating tape. The core is ready for winding the obyomotok.
Choice of windings. For primary (seteyovy) winding it is better to use the spetsiyoalny copper winding wire in x. б. (glass cloth) isolation. Udovletvoriyotelny heat resistance also wires in rubber or rezinotkanevy isolation have. Are unsuitable for work at the increased temperature (and it zayokladyvatsya already in the design любительского by S.A.) wires in polyvinyl chloride (PHV) isolation because of its possible rasyoplavleniye, effluence from windings and their short circuit. Therefore polikhloryovinilovy isolation from wires необходимо or to remove and wind wires on all length x. б. the insulating tape or not to remove, and to wind the wire поверх isolation. Also other way of winding, proyoverenny in practice, is possible. But about it below.
At selection of section of winding proyovod taking into account specifics of work of S.A. (peyoriodicheskiya) we allow current density 5 And/mm2. At current of welding 130 - 160 And ( de electrode = 4 mm) the power of secondary winding will be P2 =isv x 160x24 = 3,5 - 4 kW, the power of primary obmotyoka taking into account losses will be about 5 — 5,5 kW and consequently, the maximum current of primary winding can reach 25 A. Therefore, the section of the wire of the peryovichny winding of S1 has to be not less than 5 - 6 mm. In practice it is desirable to isyopolzovat the wire with a section of 6 - 7 mm2. Or it is the rectangular tire, or the medyony winding wire diameter (without isolation) 2,6 - 3 mm. (Calculation for the known formula S = pir2, where S — the area of the circle, mm2 пи = 3,1428; R — the radius of the circle, mm.) At the insufficient section of one wire winding in two is possible. At the isyopolzovaniye of the aluminum wire its seyocheniye needs to be increased by 1,6 - 1,7 times. Whether it is possible to reduce the section of the wire of the network winding? Yes, it is possible. But at this S.A. will lose the required stock of power, will quicker heat up and the rekomenyoduyemy section of the core of S = 45 - 55 cm in this case will be unfairly big. The number of rounds of the primary winding W1 is defined from the following the sootnosheyoniya: W1 = [(30 - 50) :S] x U1gde 30-50 - constant coefficient; S — the section of the core, cm2 , W1 = 240 rounds with branches from 165, 190 and 215 rounds, i.e. through each 25 rounds.
The bigger number of withdrawal of the network winding as practice shows, netseyolesoobrazno. And that is why. At the expense of the umenyyosheniye of number of rounds of primary winding both S.A. power, and Uxx increases that leads to increase in the napryayozheniye of burning of the arch and deterioration in the kacheyostvo of welding. Therefore, only the izmeyoneniye of number of rounds of primary winding it is impossible to achieve overlapping of range of svarochyony currents without welding deterioration. For this purpose it is necessary to predusmotyoret switching of rounds of the secondary (welding) winding of W2.
Secondary winding of W2 has to soderyozhat 65 - 70 rounds of the copper izolirovanyony tire with a section not less than 25 mm (better with a section of 35 mm). Quite podoyyodt also the flexible cable (the nayoprimer, welding) and three-phase siloyovy the multi-conductor cable. The main thing, the seyocheniye of power winding should not be less required, and isolation — teployostoyky and reliable. At the insufficient section of the wire winding in two and even in three wires is possible. When using the aluminum wire необходимо to increase its section by 1,6 - 1,7 times.
Fig. 5. Fastening of conclusions of windings of SA: 1 — the SA body; 2 — washers; 3 — the terminal bolt; 4 — the nut; 5 — the copper tip with the wire.
The difficulty of acquisition pereklyuchateyoly on big currents and the practician is poyokazyvat that it is the simplest to get conclusions of the welding winding through copper tips under terminal bolts of diayometry 8 - 10 mm (fig. 5). Copper tips make of copper tubes of suitable diameter 25 - 30 mm long and fix on wires molding and it is desirable pro-soldering. Let's especially stop on the order of the namotyoka of windings. General rules:
- Winding has to be made on the isolated core and always in one direction (for example, clockwise).
- Each layer of the winding is isolated the layer x. б. for isolation (to fiber glass fabric, the elekyotrokartona, tracing-papers), it is desirable with the proyopitka bakelitovy varnish.
- Conclusions of windings zaluzhivat, maryokirut, fix x. б. the tape, on vyyovoda of the network winding in addition nayodevat x. б. cambric.
- In case of doubts in quality of the izoyolyation winding can be carried out with the isyopolzovaniye of the cotton cord kind of to two proyovod (the author used x. б. thread for the ryyobolovstvo). After winding of one layer the winding with x. б. thread fix glue, varnish, etc. and after drying namatyyovat the following row.
Let's consider the order of the arrangement of windings on the c type magnetic circuit. The network winding can be raspoloyozhit in two main ways. The Peryovy way allows to receive more "rigid" mode of welding. The network obmotyoka in this case consists of two odinayokovy windings of W1W2 located on the different parties of the core, soyediyonenny is consecutive also the wires having odiyonakovy section. For the reguliyorovka of the output current on each of the obyomotok branches which in pairs become isolated are made (fig. 6a, c).
The second way provides the namotyoka of primary (network) winding on one of the parties of the core (fig. 6 in, d). In this case SA possesses krutopadayushchy hayorakteristiky, cooks "softly", arch length influences less the size of the welding current and consequently, and on quality of the svaryoka. After winding of the primary winding SA it is necessary to check for availability of short-circuited rounds and correctness of vyyobranny number of rounds. The welding transyoformator is included in network via the safety fuse (4 - 6A) and it is desirable амперметр alternating current. If the predoyokhranitel burns down or is strongly heated, then it is the strong indication of the short-circuited round. Therefore, primary obmotyoka should be rewound, having paid special attention to quality of isolation.
Fig. 6. Ways of winding of windings of SA on the seryodechnik of rod type: and - the network obmotyoka on two parties of the core; — sootvetyostvuyushchy to it the secondary (welding) winding included counter in parallel; in — the seteyovy winding on one party of the core; — the secondary winding corresponding to it included consistently.
If the welding machine strongly hoots, and the consumed current exceeds 2 - 3 And, then it means that the number of primary obyomotka is underestimated and it is necessary to podmotat still the quantity of rounds. Isyopravny SA consumes current of no-load operation no more than 1 - 1,5 And, is not heated and hoots not strongly. Secondary winding of SA is always namayotyvat on two parties of the core. For the first way of winding the secondary obyomotka also consists of two identical half included for increase in the usyotoychivost of burning of the arch (fig. 6) counter in parallel, and the section of the wire can be taken slightly less — 15 - 20 mm2 .
For the second way of winding the main welding winding of W21namatyvayetsya on the party of the core, free from windings, also makes 60 - 65% of the total number of rounds of secondary winding. It serves in the basic for ignition of the arch, and during welding, due to sharp increase in the magyonitny flow of dispersion, tension on it falls for 80 - 90%. The Dopolnitelyyony welding winding of W22 is reeled up over primary. Being power, it supports nayopryazheny weldings and consequently, and svayorochny current in required limits. Tension on it falls in the welding mode for 20 - 25% concerning tension of no-load operation. After S.A production it is necessary to carry out its setup and the inspection of the kacheyostvo of welding by electrodes of the different diayometr. Process of setup consists in the following. Measurement of the welding current and tension requires priobresyot two electrical measuring instruments — the alternating-current ampermeter on 180 — 200 And yes the alternating current voltmeter for 70 - 80 century.
Fig. 7. Ways of winding of windings of SA on the seryodechnik of toroidal type: 1.2 — ravnomeryony and section winding of windings sootvetstyovenno: and — network — power.
Fig. 8. Scheme of connection of measuring apparatuses.
The scheme of their connection is shown in fig. 8. When welding by different electrodes remove values of current of welding — Isv and tension of welding of Usv which dolzhyona to be in required limits. If svayorochny current is small that happens most often (the electrode sticks, the arch unstable), then in this case or switching of peryovichny and secondary windings ustanavliyovat desired values, or pererasyopredelyat quantity of rounds of secondary winding (without their increase) towards increase in number of the rounds which are reeled up поверх the network winding. After welding it is possible to make the break or sawing of edges of the welded products, and the quality of welding will become clear at once: depth of the penetration and thickness of the nayoplavlenny metal layer. On observed datas it is useful to soyostavit the table.
Proceeding from data of the table, choose the optimum modes of welding for elekyotrod of different diameter, remembering what when welding by electrodes, for example, with a diameter of 3 mm, electrodes with a diameter of 2 mm it is possible to cut since current of cutting is more welding for 30 - 25%. The difficulty of purchase of the measuring apparatuses recommended above zayostavit the author at to begnut to the izgotovleyoniya of the metering circuit (fig. 9) on the bayoza of the most widespread milliyoampermetr of the direct current on 1 — 10 mA. It consists of the measuring instruments of tension and current assembled on the full-wave circuit.
Fig. 9. Key diagram of measuring instruments of tension and current of welding and current transformer design.
The measuring instrument of tension connect S.A. Nayostroyka to the put-put (welding) winding carry out by means of the lyuyoby tester which control the voltage output of welding. With помощью the variable resistance of R.3 to the shooter of the device establish on koyonechny division of the scale at maksimalyyony Uxxshkala value of the measuring instrument of tension it is rather linear. For best accuracy it is possible to remove two - three control points and to graduate the measuring device on measurement of tension.
It is more difficult to adjust the current measuring instrument as it is connected to samoyostoyatelno to the made current transformayotor. The last represents the core of toroidal type with two obyomotka. The core sizes (the outer diameter of 35 — 40 mm) of basic value have no, the main thing that windings umesyotitsya. Core material — transformer steel, permalloy or ferrite. Secondary winding consists of 600 - 700 rounds of the copper insulated conductor of the PEL, PEV brand, PELShO with a diameter of 0,2 - 0,25 mm and the podyoklyuchena to the current measuring instrument is better. Primary obyomotka is the power wire passing in the ring and connected to the terminal bolt (fig. 9). Setup of the measuring instrument of current consists in the following. Connect kayolibrovanny resistance from the thick nikhromovy wire on 1 - 2 sec. to the power (welding) winding of S.A. it (is strongly heated) and measure tension at S.A. exit. Determine the current proceeding in the welding winding by the Ohm's law. For example, at connection of Rn = 0,2om Uvykh = 30 century.
Note the point on the instrument scale. Three - four measurements with different RH doyostatochno to calibrate the izmeriyotel of current. After calibration devices usyotanavlivat on S.A body, using obyoshcheprinyaty recommendations. When welding in different conditions (strong or low-current network, the long or short bringing cable, its seyocheniye, etc.) switching of windings nayostraivat S.A. on the optimum mode of welding, and further the switch can be usyotanovit in neutral situation. Several words about contact spot welding. The number of specific requirements is imposed to S.A. designing this type:
- The power given to the welding moment has to be the maximum, but no more than 5 — 5,5 kW. In this case current, potrebyolyaemy from network, will not exceed 25 A.
- The mode of welding has to be "zhestyoky" and consequently, winding of windings of S.A. has to be carried out on the first vayoriant.
- The currents proceeding in the welding obyomotka reach values 1500 — 2000 A and above. Therefore, tension of the svaryoka has to be no more than 2 — 2,5v, and the nayopryazheniye of no-load operation — 6 — 10 century.
- Section of wires of primary obmotyoka not less than 6 — 7 mm, and the section of the vtorichyony winding is not less than 200 mm. Reach such section of wires by winding of 4 — 6 windings and their subsequent paralyolelny connection.
- Additional branches from pervichyony and secondary windings to do netseleyosoobrazno.
- The number of rounds of primary winding can be taken S.A., minimum rated in connection with short duration of work.
- Section of the core (core) less than 45 — 50 cm is not recommended to be taken.
- Welding tips and podvodyony cables to them have to be copper and pass the corresponding currents (диаметр tips of 12 — 14 mm).
The special class of amateur S.A. is predyostavlyat by the devices manufactured on the basis of industrial lighting and druyogy transformers (2 — 3 phase) on voltage output 36v and with power not less than 2,5 — 3 kW. But before браться for alteration, it is necessary to measure the core seyocheniye which has to be not less than 25 cm, and diameters of primary and secondary windings. At once it will become clear to you what it is possible to wait from alteration of the danyony transformer for.
And in conclusion of several tekhnologiyochesky councils.
Connection of the welding machine to network has to be made by the wire of seyocheniy 6 — 7 mm via the automatic machine on current 25 — 50 And, for example AP-50. Diameter of the electrode depending on thickness of the welded metal can be chosen, proceeding from the following the sootnosheyoniya: da = (1—1,5)L, where L — thickness of svayorivayemy metal, mm.
Length of the arch is chosen depending on diameter of the electrode and is on average equal to 0,5 — 1,1 d3. It is recommended to carry out welding by the short arch of 2 — 3 mm, napryazheyony to which 18 — 24 Century are equal. Increase in length of the arch leads to violation of the stayobilnost of its burning, increase in losses on waste and to spraying, decrease in the gluyobina of pro-melting of the main metal. The arch is longer, the welding tension is higher. Speed of welding is chosen by the svaryoshchik depending on brand and thickness of metal.
When welding on direct polarity plus (anode) is connected to the part and minus (cathode) — to the electrode. If необходимо that on the part the smaller amount of heat was generated, for example, when welding thin-sheet designs, priyomenyat welding on the return polarity (fig. 1). In this case minus (cathode) is priyosoyedinyat to the welded part, and plus (anode) — to the electrode. At the same time not only smaller heating of the welded part is provided, but also accelerates процесс meltings of electrode metal due to more high temperature of the anodyony zone and the bigger heat input.
Welding wires attach to SA through copper tips under terminal bolts from the outer side of the body of the welding machine. Bad contact connections reduce power characteristics of SA, worsen quality of welding and can cause them перегрев and even ignition of wires. With the small length of welding proyovod (4 — 6 m) their section has to be not less than 25 mm. When performing welding works необходимо to follow rules of fire and electrical safety during the work with elektroyopribor.
Welding works should be conducted in the special mask with the protective glass of the C5 brand (on currents to 150 — 160 And) and mittens. All switchings of SA выполнять only after disconnection of the svarochyony device from network.Top