DE1807607C - Method and device for soldering workpieces - Google Patents

Description

The invention relates to a method for soldering workpieces and the like a hot gas flow is applied directly to heating to the soldering temperature. Further The invention relates to a soldering device for performing the soldering process.

The invention is particularly advantageous for driving that of the flame or the radiation soldering the socket pipe connections between the heat directly applied front of the Pipes and the pipe elbows from thin-plate soldering point is overheated, so that the solder alloy here Applicable to heat exchangers, although it is also excessively thin. In both cases this is the result Other workpieces are used for brazing. can. Thin-plate heat exchangers are made with the known methods and devices usually ^ us a multitude parallel at a distance it is also very difficult to achieve at copper tubes arranged in relation to one another are produced, a larger number of which are to be produced at the same time Via the number of soldered connections at a short distance from one another, the individual soldering points are uniformly anomalous Aluminum fins are pushed to heat up io. This requires time consuming engineering serve as heat radiation surfaces. Near the positions of the burner and building-intensive Vorrich-Rohriiden is a galvanized sheet steel as head hangers.

pieces arranged. The ends of the copper pipes are sa of the past, numerous attempts are made to un-

Connected via U-shaped copper pipe elbows. been taken to deal with the overheating and

The connection of these pipe elbows to the copper-15 related to insufficient heating-

pipes is usually done by means of a muffle pipe to remedy the difficulties. For example, has

and solder joint. The soldering of the solder alloys with such a melting temperature

Parts are mostly made in such a way that the socket temperature range is used so that »*> e correct flow

end of the tubes' a made of a solder alloy »» consists :. properties of the lot itself are preserved,

the ring is placed, whereupon the connection ao if the solder joint is heated unevenly. Such

and the solder alloy by pulling it from the outside.

led heat to the melting temperature of the solder alloys, which is a narrowly defined melting temperature

alloy, which is generally at 820 ° C, have brought comparatively expensive,

will. The melting solder alloy flows here - especially when using a burner -

in the case of capillary action in the gap at the »5 flame to heat the solder joint results in

liaison office. In order to achieve a satisfactory soldering vein, the known methods and devices are not

To achieve a bond, the temperature of the overall seldom has the disadvantage that the soldering process takes place in the

th connection at least takes place on the melting temperature air atmosphere. Even when in use

door of the solder alloy, however, a reducing flame is immediately after

care must be taken that the connection at the end of the heating process the hot copper

no point is heated to such an extent that the solder alloy is exposed to the oxygen in the atmosphere

tion boils or becomes so thin that its effect very quickly turns it into a black color.

Connection flows. The copper oxide is oxidized, which is undesirable.

It is known that the soldering point can be heated by means of Finally there is also the risk that when using

make a high temperature flame, the 35 generation of a flame the flux used oxy-

Temperature is around 1650 ° C and are not averaged when they are at the high temperatures

bar is brought to act on the solder joint. exposed to the atmosphere.

In addition, it is known to use heating alone. The aforementioned disadvantages at least exist

caused by radiant heat. Iu both cases, partly also at another known facility

However, the solder joint on the front side, i.e. H. 40 device for soldering heat exchangers where the

on the side that is before. the flame immediately heats the workpiece in a directional manner

is touched or which takes place in the jet path of the heat-gas flow of a fan circulation system,

stranlers lies, immediately heated, while the rürk- Again there is the danger that the soldering point is on

or the shadow side of the solder joint only inadequate directly on the side facing away from the gas flow

Giund the heat conduction of the metal; heated from the previous day or at the point where the gas flow

the side of the solder joint is heated, which overheats a turned side. Since, in addition,

requires a certain heating time. sem known method with a circulating

One of the main difficulties in warming gas is the circulating gas can be under Soldering point by means of a flame or by means of a radiator consists in all soldering points of the ta inen, which lead to an oxidation of the soldering point Heat exchanger at the same time in the would be required. A disadvantage of this known device Dimensions to heat up and at the same time each individual is finally also that here the workpiece first Solder joint heated in the shortest possible time on the whole in a preheating oven and then in Circumference must be brought evenly to the soldering device to bring the actual soldering furnace in gen. Since in the known methods and equipment, the soldering process takes place, The aforementioned disadvantages are self-related Back of the soldering point essentially only of course even if instead of heat through Heat conduction is heated and there other- exchangers other workpieces, which may be on the other hand, the temperature gradient required for this does not take up a large number of solder joints in a narrow space may be too large to prevent overheating of the soldering 60 to be soldered.

place to avoid at the front, arises in After the above, the invention is therefore the

In practice, the task of creating a process is often based on insufficient heating

Soldering point on the back of the soldered connection with which the aforementioned disadvantages of the known

the consequence that the solder alloy is not always effectively eliminated in driving. In particular, should the required> 4ass is melted. If 6j with the method according to the invention is a rapid

on the other hand, the heating of the soldering point so through and even heating of the soldering point or a leads to the fact that the soldering point can also be reached in the multitude of soldering points on the back side, with each other

is heated in the desired manner, there is a need to use cheaper soldering alloys for soldering.

let him. The invention also aims at a soldering device with which the method according to the invention can be carried out in an expedient manner.

The inventive method is characterized in that the soldering point in the vortex zone a mixed gas flow is heated by mixing a hot inert gas flow, the temperature of which is considerably higher than the soldering temperature, with an inert cold gas flow is formed, the temperature of which is considerably below the soldering temperature, wherein the temperature of the mixed gas flow for heating the soldering point is controlled by changing the gas mixture ratio so that the soldering point is initially heated to a temperature below the soldering temperature under the action of the mixed gas flow surrounding it, and that then, in order to melt the solder, it is exposed to a mixed gas stream, the temperature of which is above the soldering temperature.

In this method, the workpiece provided with the solder can thus initially be subjected to the action a mixed gas stream, the temperature of which is close to the soldering temperature of the solder, subjected to preheating and then for rapid melting of the Lots are subjected to the action of a hotter mixed gas flow, the temperature of which is slightly is above the soldering temperature.

One is particularly advantageous with regard to rapid and uniform heating of the solder joint Mode of operation in which the temperature of the mixed gas flow is controlled so that with increasing heating of the workpiece and the solder, the temperature of the mixed gas flow from a temperature which is significantly above the melting temperature of the solder, to a temperature close to the melting temperature of the Lots lying temperature is lowered that the workpiece and the solder to an immediately below the melting temperature lying temperature are uniformly heated. Then the The temperature of the gas flow is raised to a temperature above the melting temperature, until the solder is completely melted. With this procedure therefore takes place due to the high Starting temperature of the mixed gas flow a very rapid heating of the soldering point up to a temperature that is slightly below the melting temperature of the I. «(alloy lies. This can be achieved without local overheating can occur. The soldering is then melted, as mentioned, by briefly increasing the temperature Mixed gas flow.

In the method according to the invention, the workpiece is at the soldering point by a mixed gas flow applied, the speed of which is so great that a gas turbulence occurs at the I otstcllc, at which the fluidizing gas flows around the solder joint on all sides and is thus heated very evenly. the the side of the solder joint that is applied to the gas flow So here not primarily through thermal conduction of the workpiece metal ciwärml, but rather directly through that which flows around the I 'HsIcIIc on all sides Gav The said vortex can be improved according to the invention by the fact that the mixed gas flow brought to expansion in the area of the soldering point of the workpiece wi / il.

I ÜF den Misthgasslroni is expediently the exhaust gas from a fuel burnt in a cini-m burner system h used. The Bicnnersystcm for the hot gas flow is expediently at such a distance from the soldering point for combustion brought that the soldering point only from the exhaust gas flowing at high speed, but not is acted upon by the ram itself. The mixed gas flow can be made up in a simple manner from a hot exhaust gas flow and one branched off from it Produce a gas stream that is cooled and then reunited with the hot exhaust gas stream. In this

In this case, the two gas flows can be generated by means of a single burner system. on the other hand but two burner systems can also be provided for the separate generation of the two exhaust gas flows the exhaust gas flow of one combustion system

stems subjected to cooling and then mixed with the exhaust gas flow of the other burner system will.

It is advisable to carry out the process according to the invention in such a way that the mixed gas

ao bcigang is discharged into the atmosphere at the soldering point. Furthermore, it is in view to avoid oxidation of the soldering point, the heating of the soldering point by the reducing mixed gas in one against air ingress

perform as substantially protected vortex chamber and to cool c \ z Ϊ ötstelle After the solder operation by an inert cooling gas stream, before the soldering area of the workpiece is exposed to air.

According to a further feature of the invention, the two mentioned, the mixed gas flow forming gas flows are brought together in the mixing chamber so that the hot gas flow from an im Enclosed relationship to this cooler gas stream or is sheathed. This is especially the Prevents heat radiation of the hot gas flow to the outside.

The device for performing the method according to the invention has, in addition to the device, to

Generation of an inert hot gas stream a device for generating the inert potash gas stream, also a mixing chamber for mixing the two gas streams and a device for changing the Gasmischungsverhähnisses on. Here is the

Chamber serving mixed gas supply on the side facing the gas supply cables give away an opening in which the workpiece to be soldered is in the soldering position. Preferably is at the workpiece end of the mixing chamber

a gas expansion chamber is arranged in which the supplied mixed gas expands in the workpiece area and thereby brought to an intensive vortex will. In order to achieve this expansion effect, the mixing chamber receives mutually converging

Walls or wall parts which form a gas supply channel that narrows in the shape of a funnel or nozzle towards the expansion and vortex chamber. The swirl chamber or the expansion chamber is useful for discharging the gases from the solder joint

provided with gas outlet openings that cross the Flow direction of the mixed gas run.

According to a further feature of the invention, the mixing chamber has a casing that surrounds the chamber wall at a distance, the

Space between the chamber wall and the casing is connected to the Kallgaszufühningslcitung. expediently such that the supplied Cold gas in countercurrent to that of the mixing chamber

flowing through gas mixture flows and thus the Mixing chamber enveloped in the manner of a jacket. It is recommended that the mixing chamber be fitted with a double jacket to provide ", whereby the Doppelmanclraum e <! e air chamber, which due to their insulating effect Heat loss largely reduced.

According to a further feature of the invention is that of the workpiece receiving opening opposite At the end of the mixing chamber there is at least one burner for generating the hot gas stream. In the vicinity of this burner there are expediently the mentioned feed openings for the cold gas flow, preferably in such an arrangement that the cold gas, the hot gas flow in the manner of a Manlclstromcs enveloped.

As mentioned, the invention enables rapid heating of the soldered joint to a uniform temperature without the risk of overheating, which is an essential prerequisite for a good soldered connection. At the same time, cheap brazing alloys can be used. Overheating is prevented by precise temperature control of the mixed gas flow, while uniform heating is achieved by the vortex effect and the purging effect of the mixed gas flow. In addition, the invention creates the possibility of subjecting the soldering point to the reducing Äinuiüpnüic / u during the entire soldering process until the Lö'slcüc has cooled to the temperature at which rapid oxidation can no longer occur.

In the drawing is an embodiment of the Loicinrichlung according to the invention shown. Ls shows

Fig. 1 in perspective and in partial view a plate heat exchanger, the soldered connections of which with the Loicinrichlung according to the invention getting produced,

Fig. 2 in side view of a guide device according to a preferred Ausfülirungsbcispicl of the invention,

3 on a larger scale and in side view, the mouth opening of the Lölcinrichlung according to FIG. 2,

F i g. 4 in a front view, partially in section, the soldering device with the Tcmpcratursieuersjstcm, wcl flies is shown on a small scale.

Fig. 5 schematically shows a Silinlldiauramni des lempcraluvslcucrsyslcms,

6 shows a further embodiment example of a method of the invention I oil installation.

The drawing, in '3 is a previous embodiment the crfindiinjisp-appropriate locking device is daigcstelll, shows in Figs. 1, 2 and 4 a workpiece IO before the 1 iiifuhrcn in the soldering position of an assembly, which essentially consists of a Brcnncrsyslem 35 for generating a hot gas stream and a second Brenncrsyslcm 83 for generating a second exhaust gas and from a Cooling device 84 for cooling this second exhaust gas stream and a chamber 34 / in a mixture of Ixndcn exhaust gas streams before touching the Workpiece 10 consists.

The workpiece IO consists of U-shaped tubes 12, e.g. B. those made of copper, aluminum or steel, which extend through metal tubes 13. Between The metal sheets have metal ribs 14, each of which has openings 15 for receiving the tubes 12 have and which enclose the tubes tightly to to achieve a good heat exchange. The open ends of the adjacent tubes 12 are via elbows 16 connected from the same or from a different metal; the connection is made using Connection sleeves 17. On the pipe bends 16 are rings 18 from one of the intended uses appropriate solder metal attached; the rings sit on the end faces of the tubes 12 arranged sleeves in which the pipe bends engage with a snug fit. The solder metal can off a known soldering alloy, but when soldering copper it is advisable to use a cheap soldering alloy, such as B. a simple copper-zinc alloy is used, which has a narrow Schmcl / lcmpc-

iS raturbcrcich and on the contrary / u the more expensive silver-containing brazing alloys with a larger enamel area are slightly relatively thin will. When soldering aluminum, the conventional Use aluminum lole. Fs bc> il

ao also the possibility. Flux, like a solid pasia or a liquid to use.

The heat exchanger completed for the soldering process 10 is placed on a workpiece carrier 21 (FIG. 2 and 4) of the soldering device 11, so that

as he goes up into the mouth opening 22 of a soldering box 23 can be moved. The heat exchanger 10 is by means of roller pulls 25 or other Devices on the base plate 24 of the work / cugtriigcrs aligned. As shown in Fig. 2, mhu on the

Base plate 24 Rollcnpaare 26 arranged on inclined rails 27 run so that the tool carrier from the rest position shown in FIG can be lifted into the loosening position, in which the workpiece in the mouth opening of the lo

stcns 23, which is used for receiving the workpiece 10 is arranged inclined accordingly. To swirl this Huhbcwegung a drive, for. B. a Pneumatic cylinder piston assembly 28 provided, which is mounted on the foot of the rails 27.

The cylinder is via a solenoid operated control valve 29 (Fig. 4) with a compressed air source connected.

The mouth opening 22 (Γ i g. 2 to 4) of the Lolcinrichtung has on its seat 30 a sheet metal 13 of the

Heat exchanger 10 corresponding rc-Jiteckigc IJiiitißforni and is at the four Scilcnkanlcn mn funnel-shaped obliquely downwardly inclined lips, which are used to guide an upwardly directed Circumferential flange 32 of sheet 13 at the fin

so lead the workpiece in the Lölposilion serve In The circumferential flange 32 is put up in the soldering position the seat 30 from. Slightly above the seat 30 there is a wall 35a with openings 36, through which the gas is "discharged to the outside."

will. The openings 36 connect the mixing chamber 34 of the I otkasiens with an outlet chamber 37 which in turn via a line 38 and a pump 39 to an exhaust pipe 40 is connected.

The burners 35 on the top of the soldering box - »3

are used to generate a hot exhaust gas flow.

dor through d.c chamber 34 of the soldering box 23 schtit

.Dor flows down to the mouth opening 22

Biennial / can only have one or more bridge

ner 35 include: the number of burners depends

according to the circus and the dimensions of the n, 1 »i« the workpiece. IKM the dargestel.fen A usfüh _u t! bcrsprel srncl over the upper end wall 42 of the I ™ fi. stons, erte.lt eight burners vorg _{se lcn} , _d ; _c J 'J ^

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horizontal alignment line are arranged. The burners 35 are connected to a common collecting line 43 for supplying the fuel gas-air mixture. The line 43 is connected to a mixing device, such as. B. a venturi 44 connected to the the fuel gas is supplied via a gas supply line 45 in which a solenoid operated by a Shut-off valve 46 and a pressure regulator 47 are arranged. Furthermore, the venturi is connected to a Air supply line 48 connected, via which the combustion air is supplied and in the one pneumatic, membrane-operated air control valve 49 and a pneumatically operated shut-off valve 50 are arranged are. A Gehläse 51 conveys the air into the line 48. The amount of the venturi tube flowing combustion air is regulated by means of the valve 49, while the supplied and with the amount of gas mixing the combustion air is regulated through the venturi so that the amount of fuel gas is approximately directly proportional to the amount of combustion air. The burners 35 echo hence a combustible mixture with essentially egg constant fuel-air ratio supplied. In a ceramic head piece 54 of the Brcn In 35 a pilot flame 53 'is arranged, which the mixture at one end of the burner row ignited. The burner flame that is set up when it is ignited can pass through between the neighboring Channels arranged in the head piece by burners 56 and thereby ignite all burners when ignited. Every burner flame 55 passes through a furnace tunnel 57 in the ceramic head piece; it also forms a hot exhaust gas flow 58. The individual exhaust gas flows from the burners diverge by about 12 'compared to their respective ones Brenner tunnel 57 and form a laminar gas flow of high gas velocity. Every burner tunnel 57 widens on the outside via a number of shoulders 59 (FIG. 2), creating a flame turbulence and a shortening of the flame 55 is achieved. The air-fuel mixture is proportional adjusted so that the fuel is always available in a small excess, so that the forming Exhaust gas 58 has reducing properties and a temperature substantially equal to the temperature the burner flame, which is around 1650 Γ.

This temperature must be reduced considerably before the exhaust gas stream hits the workpiece. This is done by mixing the gas with a cold stream of exhaust gas. This cold exhaust gas can be generated by branching off a partial flow from the hot gas flow 58 and passing it over a cooling device. However, a special exhaust gas generator 82 (FIG. 4), which has a burner 83 and a cooler 84 , is preferably provided for generating the cooling gas. The fuel gas supplied via a line 41 and the combustion air supplied via a line 48 are mixed in a venturi tube 86 so that a constant fuel-air ratio is maintained, as was explained above in connection with the venturi tube 44. The mixture flows via a line 87 to the burner 83 at the top of a ceramic chamber 88 of the gas generator 82. The regulation of the exhaust gas generator can take place in a conventional manner. The Hi.iiii-.Uiff-Lr *: ratio is always m »set so that a reducing exhaust gas with a temperature of approximately 1650 ° C is generated. This hot exhaust gas flows through the chamber 88 and a line 89 into the cooler 84, to which cooling water is fed to the top of a jacket duct 90 on the circumference of the chamber 88 via a line 91. The cooling water circulates around the chamber 88, then flows through an opening 92 into the cooler and washes around the line 89 before it leaves the cooler via an outlet 93. Additional cooling water is supplied via a second supply line 94 on the bottom side of the cooler 84 and, after passing through the cooler, is also drawn off via the line 93. In the second cooling water duct 94 there is arranged a control valve 95 which is influenced by an adjustable cooling water temperature sensor 96 on the outlet side 93 so that the temperature of the exhaust gas can be adjusted as a result.

ao The line 89 of the cooler 84 is connected to a cooling gas line 66, which is also connected to a cooling gas branch line 97, which passes through the cooler 84 and is connected to a cold gas line 81. In the lines 66 and 81 as throttle valves 98 and 99 are arranged, which are connected to one another with a pneumatic actuating device 100 so that in each case one throttle valve is closed when the other is fully open.

The cooled exhaust gas is fed to the soldering box via line 66 and injected into the chamber via openings 61 in a wall arranged in the direction of flow immediately behind the combustion tubes 57, the direction in which the cooling gas is introduced via openings 61 being selected in this way. that the gas enters the chamber 34 essentially perpendicular to the axis of the flames 55 and the gas streams 58 and thereby envelops the hot gas streams in the manner of a sheath stream. As a result, the heat transfer from the hot gas flows to the side wall 63 of the chamber 34 is reduced. At the same time, the temperature of the hot gas streams 58 is thereby reduced, with laminar and reducing mixed gas streams 64 being formed. The chamber wall 63 is surrounded on the outer cable by a jacket 67 which forms a circumferential chamber 65 which is connected in the lower region to the line and in the upper region to the openings 61 for the introduction of the exhaust gas into the chamber 34. The supply of the gas via the jacket space 65 reduces the heat transfer from the outer chamber 34 to the outside air. The gas supply line 66 opens into the peripheral wall 67 directly above the mouth opening 22 of the soldering box. An air chamber 68 is formed between the wall 67 and an outer jacket wall 69 of the oil box in order to further reduce the heat losses. In the vicinity of the lower end of the chamber 34, the chamber side wall 63 has a section 71 with inwardly converging walls, which here forms a nozzle 72 on the underside of the wall 63. This nozzle opens into an expansion chamber 73 enclosed by the wall 35 α, which is arranged at a distance below the nozzle 72 and at a distance above 65 in the 1 otposition workpiece 10, so that the mixed gas flow 64 when passing through the converging wall parts 71 formed channel as well as by the

Nozzle 72 is compressed and then expands abruptly behind the nozzle in <Jcr expansion chamber 73. The gases coil around the soldered joints and then flow out to the outside via the outlet openings 36. In the illustrated embodiment, the flows Exhaust gas through nozzle 72 at a speed of about 1525 to 9150 m / min. This speed is sufficiently large to have a strong flushing effect for the turbulent gases on the workpiece surface achieve so that the heat on all surfaces the pipe connections is transmitted quickly.

Cold reducing gas 71 may be arranged openings 79 inserted into the expansion and swirl chamber 73 via the line Sl and iin lower portion of the converging Seitcnwändc, so that it can flow around the workpiece 10 under turbulence at a high speed and cool it. The openings 79 open into a chamber 80 on both sides of the converging chamber. Seitenwäncle 71. The chamber 80 is in turn connected to the cold gas supply line 81 . The cold exhaust gas is drawn off from the chamber 73 via the outlet openings 36

The device described above works as follows: When the workpiece 10 has been placed on the workpiece carrier 21 located in the lower rest position, the gas valve 46, the air shut-off valve 50 and the cooling gas valve 98 are opened; at the same time, the air valve 49 is set to a low air supply amount. The pilot flame 53 ignites the burners 35 without significant back pressure in the chamber 34. The chamber 34 is then heated to a temperature of about 540 ° C. in about 10 seconds.

The gas flowing through the venturi 86 and mixed with the air supplied by the blower 51 is burned in the burner 87, with the exhaust gases flowing through the chamber 88 at a temperature of about 1650 "C. The air-fuel mixture becomes so This exhaust gas flows through the cooler 84 and is here cooled to a temperature of, for example, approximately 318 C. The cooled exhaust gas then flows via the line 66, the valve 98, the line 65 and the channels 61 into the chamber 34. The fan 39 continuously draws the gas from the chamber.

The device is now ready for use. By actuating the lifting cylinder 28 by means of the control valve 19 , the tool carrier 21 with the workpiece 10 is brought up into the soldering position in which the workpiece lies in the mouth opening 22, as shown in FIG. 2 is indicated by dashed lines.

In order to avoid oxidation on the inside of the copper pipes 12 and the pipe bends 16 during the soldering process, the air can be removed from these parts and a (not shown) Gas source delivered exhaust gas are passed through the coil.

The valves 46 and 49 are then fully opened, so that the burners 35 are supplied with a fuel-air mixture which burns in the burners with an exhaust gas temperature of about 1650.degree. The hot exhaust gas flows downward in the chamber 34 and mixes with the cooling gas which flows into the chamber via the channels 61. The two gas flows flow as a mixed gas flow down to the mouth opening 22, wash around the soldering points and then flow under the suction effect of the fan 39 via the openings 36 to the exhaust gas duct 40. The gas volume flowing through the neck piece 30 is adjusted so that the gas speed is at least as great is that a violent gas turbulence is achieved together with a flushing effect, in which the pipe bends 16 are washed by the gas and heated in all surface areas simultaneously and evenly. In order to achieve the desired flushing effect, a gas speed of over 610 m / min, preferably in the order of magnitude of 3050 m / min, is sufficient. The maximum speed is reached when the solder alloy is entrained by the gas into the gas outlet when it melts.

The temperature of the mixed gas stream obtained from the two gas streams is precisely adjusted. This can be done by controlling the fuel and fuel supplied to the burners 35 and / or the burners 83

ao air quantity '' can be reached. But there is also the Possibility to keep the fuel and air quantities fed to the two burner sets in a constant ratio to keep and the temperature control instead via the degree of cooling of the exhaust gases

as burner 83 to effect. There is also the possibility of discharging a more or less large part of one or the other gas stream into the atmosphere for temperature control. If only a single burner set is provided for generating the two gas flows, the proportion of the partial flow diverted from the hot main flow and passed through the cooler 84 can be changed. In any case, the temperature of the mixed gas flow formed from the two gas flows at the beginning of the workpiece loading is preferably higher than the melting temperature of the solder metal rings 18 in order to achieve rapid heating of the soldered joints.

An electronic temperature sensor and control

The control 105 senses the temperature of the pipe elbows 16 and the solder metal rings 18 . When the temperature of these parts approaches the melting temperature of the solder metal rings, an electrical signal is sent to an electropneumatic converter 106 in the

♦ 5 released pneumatic control circuit, whereby the gas and air supplied to the burners 35 is reduced. Since the amount of cooling gas consumed, the temperature of the mixed gas stream flowing into the soldering points 16 is reduced to a value which is so close to the melting temperature of the soldering alloy that heat losses at the soldering points are compensated for by conduction and heat radiation. These gases flow around the soldered joints at high speed until their temperature is constant in all areas. This process can be started as a preheating period in which the preheating temperature is preferably just below the melting temperature of the solder metal rings 18. At the end of the preheating period, the rings 18 are therefore still largely solid.

After the preheating period has ended, the actual soldering period begins. The amount of gas and air supplied to the Venturi tube 44 is so because Increased that the gas flowing into the pipe elbows 16 receives a temperature which, for. B. is 18 bl · 228 ¹ C above the soldering temperature, around the rings 18 after preheating quickly air / uschmel

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Zen. This can generally be done in about 7 to 8 seconds execute. The melted solder all flows due to the capillary action between the Pre-welded sleeves of the pipes 12 and the spigot ends of the pipe bends 16 adapted to the sleeves.

At the end of the soldering period, the torches 35 are opened by shutting off the gas and air valves 46 and 50 switched off, the cooling gas valve 98 is closed at the same time and the gas valve 99 opened. The exhaust gas flows at a cold temperature of around 38 ° C via the line 81 and the openings 79 of the expansion chamber 73 to where it cools the workpiece 10 to a temperature below that Temperature is at which rapid oxidation can set in about 75 seconds. The feed of the reducing cold gas takes place until the temperature of the copper bends 16 is below the oxidation temperature of the copper (260 C "). This prevents the pipes from being exposed to the air and thus black, form flaky oxides. The temperature vert of 2M) C is below the softening temperature of aluminum.

Then the control valve 29 of the pneumatic cylinder 28 can be closed and the cylinder be vented to the workpiece carrier 21 and the lower soldered and cooled workpiece 10. The entire cycle takes about 2 minutes.

Is pretended that the fan 39 in this mode of operation continuously withdraws the exhaust gases from the chamber 34, the gases at high speed in the order of magnitude of 610 ni'min or less flow past the pipe bends 16. at At this high speed, the heat is transferred very quickly to the metal. The gas has at Passing the pipe bends a very strong turbulence, so that all metal surfaces with the gas in Come into contact. The metal is not only on the side facing the gas flow, but at the same time evenly heated on the cable facing away from the gas flow. The I.otlegicrung can therefore to none during the preheating period melt. This procedure therefore allows all soldering points to be applied over their entire circumference to bring an even temperature. It should be noted that the temperature of the Workpiece only needs to be increased by about 5 to X C.

The introductory described Arbcil start-up lets control yourself in various ways, e.g. H. by ab- so feel the temperature, by a timer or according to the preferred embodiment a combination of these two Slciicrvorgüngc.

The line setting of the I.ötperiodc is controlled by means of an electrical and pneumatic system (Fig. 4 in ^c ), so that an ignition period for the ignition of the burner 35, a preheating period, a soldering period and finally a cooling periodc are obtained. During the preheating and Lölpciiodcn scl / .l an electrical / eitseluillkieis (Fig. 5) an electronic temperature sensor and Rcgclslcuerung 105 in operation, which to regulate the output of the burner 35 an electrical signal line in clektropncumatisclien converter 106 of a pneumatic control circuit (lig. 4) feeling I. The working air for the pneumatic circuit is drawn through a duct with a pressure of about 1.75 kg / cm.

When the blower 51 for the supply of combustion air and the exhaust gas extractor 39 are in operation and the pilot flame 53 is burning, a start push-button switch 108 is briefly depressed, whereby a circuit is closed which energizes a time delay relay 1 TR , so that its both contacts 1 TR 1 and 1 TR 2 normally open and thus the ignition period is started. The contact 1 TR 1 forms a hall circuit for the relay 1 TR and closes an excitation circuit of a relay ZTR operating with a delay. When contact 1 TR 2 closes, the circuit of the three valves 46, 109 and 110 (FIG. 4) actuated by the solenoid coils is closed, so that these valves are opened. The gas flows through the opened gas shut-off valve 46 in line * 45 to the venturi 44. The valve 109 is located in a branch line 111 between the control air supply line 107 and the actuating device of the shut-off valve 50 in the air supply line 48 to the burners 35. When energized, this opens Valve 109, so that the valve 50 is opened and the combustion air can flow to the burners 35. The valve 110 is in another branch line 112 between the control air supply line 107 and the diaphragm actuator 100; it opens so that the air can flow to the actuating device and thus the cold gas valve 99 is closed and the cooling gas valve 98 is opened. The cooling gas therefore flows through the openings 61 below the burner tunnel 57 into the chamber 34. During the ignition period, the air control valve 49 in the air supply line 48 is in a position in which only a small amount of air flows to the burners 35. Control is provided by the low air pressure from a solenoid operated three-way control valve 114 in a branch line 115 and the control air flow line 107.

After a delay of about 10 seconds, ie after a period of time within which the burners 35 are ignited by the pilot flame 53, the relay 2 IR responds. so that its three contacts 2 TR 1,1TRl and 1 IR 3 close and thus end the ignition period and at the same time switch on the preheating period. When contact 2 TR 1 closes, an immediately responding delay relay 3 TR is energized. Closing the contact ITRI actuates a pressure air valve 114 which switches on the pneumatic converter 106 to control the hot gas temperature in the chamber. The contact ITR 3 closes the circuit of the normally closed, solenoid-operated control valve 29 of the compressed air cylinder 28, this valve being opened so that the compressed air acts on the cylinder 28 and thus the workpiece 10 is brought into the solder joint in the mouth opening 22. The preheating temperature is set by hand at a control station 116, which has closed contacts 3TR1 and 3TR 3 in a circle and supplies the temperature controller 105 with an electrical signal. The temperature control device also receives an electrical signal from a temperature sensor, such as / .. H. a thermocouple 117 (Fig. 3), which scans the Huißgastcmpcratur at the Muiidöffung of the Lölkaslens and an electrical signal to the electropncumatisclien converter in a line 117if between the air supply - /. u (ühriing.slcilung 107 ιιινϊ

the three-way valve 114 transmits, whereby the amount of the burners 35 supplied combustible mixture and thus the hot gas temperature is regulated. ^6th

The soldering period begins at the end of the delay period of relay 3 77? When its normally closed contacts 3 TR 2 and 3 77? 3 open. This opens the circuit of the manually operated preheating temperature control station 116 and at the same time the normally'Oifencn contacts 3TR4 and 3TRS of the said relay are closed, so that a circuit between a corresponding, manually adjustable soldering temperature control station 118 and the temperature control device! 05 is closed. The temperature control device supplies an electrical signal to the converter, as a result of which the quantity of the combustible mixture supplied to the burners 35 and thus the hot body temperature acting on the workpiece are increased. At the end of the delay penode of relay 3 7 R , its contact 3 TR 1 closes, whereby the circuit of an instantaneous delay relay 4 77? closed, sen u, rd D ^ soldering penode begins with the commissioning of the time relay 3 TR and ends after the delay period of the time relay 4 TR.

When actuating the relay 4 IR open! its only contact 4TRi, which switches on the cooling. This contact is only contact 1/7? 2 in a circle, so that when the contact opens, the circle of the three valves 46, 109 and 110 is interrupted and the burners 35 are switched off by the pneumatic control system and the control 110 of the exhaust gasifier is operated in such a way that it does Valve 98 closes: and valve 99 opens, with the result that cold gas is brought to act on the workpiece via line 66 and openings 79, so that the temperature of the workpiece is lowered to a temperature value which is below the temperature in which rapid oxidation takes place.

When the timing relay 1 TR reaches the end of its delay period, it opens the contact 1 IR 1. whereby the circuit of the timing relay ITR and thus its contacts are opened. The opening of the contact ITR opens the circuit of the solenoid valve 29, so that this valve closes and thus the cylinder 28 is relieved of the pressurized air. The workpiece is therefore lowered from the working position into the rest position shown in FIG.

In Fig. 6 a modified embodiment of the soldering device according to the invention is shown, in which a burner 120 produces a flame and thus an exhaust gas flow in a large cylinder furnace 121 generated. Part of the exhaust gas generated flows out of the furnace via a cooler, e.g. B. one with water spray working cooler, which is equipped with a plurality of cooling coils 122, which are in one Cooler housing 123 lie. This partial flow of exhaust gas then flows to a collecting line 124 which overflows a supply line 125 is connected to the soldering box 126. That exhaust gas stream of the Furnace that does not flow through the cooling coils 122 reaches the one opposite the burner 120 End of furnace 121; it flows from here through a water-cooled valve "127 on the top of the soldering box 126 and in this downwards into the mouth opening 128. in which the (not shown) Workpiece is located.

The cooling water required for cooling the exhaust gas control valve 127 is supplied via a line 129 which opens into a valve cooling chamber 130: it then flows through a pipe 131 to the exhaust gas cooler housing 123. It is withdrawn from said housing via a line 132. A temperature sensor 133 can be arranged in the cooling gas line 125 which actuates a valve 134 located in the water supply line 129 and thus regulates the amount of cooling water flowing through the cooler housing 123. The temperature of the cooled exhaust gas, which is preferably kept at a constant temperature value of 38 ^° C., for example, in line 125, is regulated via the amount of cooling water. Valves 135 and 136 are arranged in branch lines 137 and 138 of the exhaust gas supply line 125. These valves are alternately either in the fully open position or in the closed position. The valves are actuated by means of an actuating device 139 in the same way as the device 100 described above in the exemplary embodiment according to FIG. 4, so that when the valve 136 is closed, the exhaust gas can flow through the open valve 135 to the soldering box 126, where it mixes with the exhaust gas flow supplied via the valve 127. The output of the torch 120 is changed in the manner described above to achieve the required preheating and soldering temperatures. If valve 135 is closed and valve 136 is open, the soldered workpiece is cooled in the manner described by the flow of cooling gas.

For this purpose 2 sheets of drawings

Claims (16)

Patent claims: 1. Process for soldering workpieces u. dgL, whereby the soldering point is heated to the soldering temperature by a hot gas flow is applied directly, characterized in that that the soldering point is heated in the vortex zone of a mixed gas flow which by mixing a hot stream of inert gas, the temperature of which is considerably higher than the soldering temperature, is formed with an inert cold gas stream, the temperature of which is significantly below the Soldering temperature, where the temperature of the Mixed gas flow to heat the solder joint. by changing the gas mixing ratio is controlled so that the solder joint under the action of the mixed gas stream tmspülenden it initially is heated to a temperature below the soldering temperature and that then to melt the solder, it is exposed to a mixed gas flow whose temperature is above the soldering temperature is. 2. The method according to claim 1, characterized in that the temperature of the mixed gas stream is controlled so that with increasing heating of the workpiece and the solder Temperature of the mixed gas stream at a temperature which is considerably higher than the melting temperature of the lot, on one near the Melting temperature of the solder lying temperature is lowered that the We ^ ksUxk and the solder evenly heated to a temperature immediately below the melting temperature and that then the temperature of the gas stream to a temperature above the melting temperature Temperature is raised until the solder is completely melted. 3. The method according to claim i or 2, characterized in that the mixed gas flow from a hot exhaust gas stream and a branched off from this, again with after cooling this combined cold exhaust gas stream is formed. 4. The method according to any one of claims 1 to 3, characterized in that the supplied Mixed gas flow is discharged from the solder joint to the outside into the atmosphere. 5. The method according to any one of claims 1 to 4, characterized in that the mixed gas flow is caused to expand in the area of the soldering point of the workpiece. 6. The method according to any one of claims 1 to 5, characterized in that the heating the soldering point by the reducing mixed gas in a protected against the ingress of air Vortex chamber is made. 7. The method according to any one of claims 1 to 6, characterized in that the soldering point is cooled by the inert cooling gas flow after the soldering process has taken place. 8. The method according to any one of claims I to 7, characterized in that the hot exhaust gas flow is merged with a cold exhaust gas flow is that the hot exhaust gas flow is enveloped by the cold exhaust gas flow. 9. Soldering device for performing the method according to one or more of the claims 1 to 8, with a device for hot gas generation and one of the hot gas flow through chamber for the application of the workpiece soldering point by the gas, thereby characterized in that the soldering device in addition to the device (35, 4.3 to 51, 120, 121) for generating an inert hot gas stream etne device (82, 84, 122, 123) for generating an inert Cold gas stream, furthermore a mixing chamber (34) for mixing the gas streams and a device to change the gas mixing ratio, the chamber (34) on the the side opposite the gas supply side an opening (22, 128) for the workpiece arrangement having in the Löiposition. 10. Soldering device according to claim 9, characterized in that on the workpiece-side A gas expansion chamber (73) is arranged at the end of the mixing chamber (34) 11 soldering device according to claim 10, thereby characterized in that the expansion chamber (73) has gas discharge openings (36) which the Discharge mixed gas from the expansion chamber transversely to its direction of flow. 12. Löteinriciitung according to one of claims 9 to 11, characterized in that the mixing chamber (34) has a casing enclosing its chamber wall (63) at a distance (67), wherein the space (65) between the chamber wall and the casing to the Cold gas supply line (66) is connected. 13. Soldering device according to claim 12, characterized in that the mixing chamber (34) of a double jacket (67, 69) is enclosed, the double jacket space (68) being an air duct forms. 14. Soldering device according to one of claims 9 to 13, characterized in that on the side of the mixing chamber (34) opposite the workpiece opening (22) on the circumference of the hot gas streams axially flowing through the chamber Openings (61) for the cold gas supply are provided in such an arrangement that the cold gas envelops the hot gas flow in the manner of a sheath flow. 15. Soldering device according to one of claims 9 to 14, characterized in that the expansion chamber (73) with a separate cold gas supply (79, 80) for cooling the soldering point is provided in the workpiece soldering position. 16. Soldering device according to one of claims 9 to 15, characterized in that on the side of the mixing chamber (34) opposite the workpiece opening (22) at least one Burner (35) is arranged to generate the hot gas stream.