Patent Publication Number: US-2023147525-A1

Title: Soldering system

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application relates and claims priority to German Patent Application No. 10 2021 129 126.7, filed Nov. 9, 2021, the entirety of which is hereby incorporated by reference. 
     BACKGROUND 
     The invention relates to a soldering system, in particular a reflow soldering system, for continuous soldering of printed circuit boards along a transport direction, including a process channel which includes a preheating zone, a soldering zone and/or a cooling zone, including a covering hood and a main body, the covering hood being pivotable about a hood axis provided on the main body between a closed position, in which the process channel is closed, and an open position, in which the covering hood is open and the process channel is accessible. Furthermore, at least one drive unit is provided which includes a motor and a lifting element in such a way that the motor actuates the lifting element for opening and/or closing the covering hood. 
     By means of reflow soldering systems, so-called SMD components (surface mounted devices) are soldered onto the surface of printed circuit boards by means of solder paste. The solder paste, which is in particular a mixture of solder metal granulate, soldering flux and pasty components, is applied or printed onto the surface of the printed circuit boards for reflow soldering. Subsequently, the components to be soldered are placed in the solder paste. In the reflow soldering process, the soldering item, i.e., the assembly consisting of the printed circuit board, solder paste and components to be soldered, is preheated along the process channel in a preheating zone and, in a soldering zone, is heated to a temperature above the melting point of the solder paste. The solder paste melts and the solder joints are formed in this way. In a cooling zone—if one is present—the soldering item is cooled until the melted solder solidifies before being removed from the reflow soldering system. 
     Soldering systems for continuous soldering of printed circuit boards are known from DE 10 2019 128 780 A1, DE 10 2019 125 981 A1 and DE 10 2005 055 283 A1. 
     In the case of reflow soldering systems, the process channel is generally formed by two channel halves, an upper and a lower channel half. The lower channel half is provided in or on the main body and the upper channel half is provided in or on the covering hood. Further components, such as nozzle plates, fan units, air channels conducting the process gas, filter elements and/or cooling elements, are generally provided in or on the process channel or in or on the main body and in or on the covering hood. Overall, a desired temperature profile is thus provided along the transport direction in the process channel, the process gas being blown into the process channel, suctioned out of it, cooled in particular in the cooling zone, cleaned and fed back to the process channel. 
     The covering hood with the upper channel half, the upper nozzle plates and the further components provided on or in the covering hood can be opened and closed by means of the drive unit mentioned at the outset. In this context, it is known from machines of the applicant having the name Hotflow 3 or Hotflow 4 to secure the motor to the main body and the free end of the lifting element to the covering hood, so that the lifting element displaces the covering hood into the open position when the motor is actuated. 
     SUMMARY 
     The object of the invention is to provide a soldering system in which opening and closing of the covering hood is ensured in a functionally reliable manner without installation space being lost for other components, such as process gas cleaning units, cooling or heating elements, air channels or fan modules. In addition, the components covered by the covering hood should nevertheless be easily accessible. 
     This object is achieved by means of a transport system. Consequently, it is provided in particular that the motor is arranged on the covering hood and that the lifting element is supported on the main body, in particular with its free end, when the covering hood is displaced into the open position and/or into the closed position. 
     Because the motor is not arranged on the main body but on the covering hood, no installation space is required for the motor on the main body. Other components provided on the main body, for example process gas cleaning units, cooling or heating elements or fan modules, can consequently be installed without consideration of the drive unit and in particular the motor. Because the motor is provided on the covering hood, the motor is moved together with the covering hood even when the covering hood is opened and closed. The motor must be designed such that it lifts the weight of the covering hood with the upper channel half, with the upper nozzle plates and with the further components provided on or in the covering hood, and can lift its own weight. The wiring of the motor is also to be arranged in such a way that it is laid in or on the covering hood, and that it is also moved together with the covering hood when the covering hood is opened or closed. The invention is based on the idea of taking into account these disadvantages, but providing valuable installation space for other components in the region of the main body. 
     For support on the main body, the lifting element can provide, in particular, a free end which acts against the main body. 
     The motor can in particular be provided within the covering hood so that it is not accessible when the covering hood is closed. On the other hand, it is also conceivable to provide the motor outside the covering hood so that it is accessible when the covering hood is closed. The arrangement of the motor outside the covering hood has the advantage that the motor can be better cooled, because the temperatures within the covering hood, in particular in the region of the process zone, are relatively high. 
     Advantageously, the motor is designed as an electric motor having a drive shaft, the motor then preferably being arranged on the covering hood such that the drive shaft of the drive motor runs parallel to the transport direction. This results in a relatively slim design of the electric motor transversely to the transport direction. 
     The lifting element actuated by the motor may preferably be designed as a lifting rod or else as a threaded spindle. In particular when the motor is designed as an electric motor having a drive shaft, the lifting element can be designed as a lifting rod with a toothing, the toothing then meshing with a pinion provided on the drive shaft of the electric motor. On the other hand, it is conceivable that the electric motor comprises or drives a threaded spindle, and that the lifting element is designed as a spindle nut which interacts with the threaded spindle, or comprises such a spindle nut. The motor can also be designed as a pneumatic or hydraulic motor, and in particular provide a piston-cylinder unit. The motor is not limited to the aforementioned embodiments, but can include any type of motor that is suitable for being arranged on the covering hood. 
     Furthermore, it is advantageous if the motor is arranged on the covering hood so as to be pivotable at least to an extent about a first compensation axis running parallel to the hood axis, and if the lifting element is arranged on the main body so as to be pivotable at least to an extent about a second compensation axis likewise running parallel to the hood axis. As a result, a compensating movement of the motor and/or of the lifting element can be compensated for during the opening or closing of the covering hood. 
     Furthermore, it can be provided that the covering hood encloses a hood chamber, there being provided in the hood chamber the upper channel half having the nozzle plates, heating or cooling elements, air channels conducting process gas and/or fan modules for generating an air flow in the process channel. 
     In order to form the hood chamber, it is particularly advantageous if the covering hood comprises a frame structure having portal-type frame legs extending transversely to the transport direction, the frame legs each having a first support section directed downward toward the hood axis and a second support section likewise directed downward toward the drive unit, and a central section provided between the support sections, such that the process channel runs below the central sections. The first support sections are preferably provided on the hood axis or are formed by them. The motors of the respective drive unit are then preferably arranged so as to be pivotable to an extent on the second support sections via the respective compensation axis. 
     Furthermore, it can be provided that a heat shield for heat shielding of the motor is provided in or on the covering hood. The heat shield can be cooled passively or actively by providing suitable cooling elements. 
     The aforementioned object is also achieved by a soldering system having the features of the preamble of claim  1 , which has two long sides and which is characterized in that the hood axis is provided in or in the region of one long side, wherein the covering hood has, on its outer side facing away from the process channel, one or more hood flaps which are arranged so as to be pivotable about a flap axis, running parallel to the hood axis and provided in or in the region of the other long side, between an open position, in which the hood chamber is accessible from above, and a closed position. Such an arrangement has the advantage that the process channel is accessible from the one long side of the soldering system when the covering hood is open. The hood chamber above the upper channel half is accessible from the other long side when the hood flaps are open. In particular if the covering hood is opened during or shortly after the operation of the soldering system, very hot air and possibly also very hot process gas flows out of the hood flap. Due to the fact that the hood flaps are opened from the other long side and the hood chamber is accessible from this other long side, the hood chamber is nevertheless easily accessible even if hot air flows out of the opened covering hood. 
     The hood flaps, which can in particular be formed as thin sheet metal elements, are relatively light. For this reason, conventional opening elements, for example gas springs, are provided as an opening mechanism for the hood flaps. 
     An advantageous embodiment results when the flap axis is arranged above the hood axis in the vertical direction. 
     In this case, the design can also be such that the hood flaps in the closed position come to rest directly, or with the interposition of bearing or damping elements, on the upper side of the frame legs. 
     Furthermore, it is advantageous if the hood flaps in the closed position each have a horizontal section which is located close to the flap axis and extends in the horizontal direction, and an inclined section which is remote from the flap axis and forms an obtuse angle with the horizontal section. In particular, a handle can be provided on the inclined section, with which the respective hood flap can be opened. 
     Overall, it is conceivable that the soldering system has at least one covering hood on which two or more hood flaps are provided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further details of the invention can be found in the following description, which describes and explains an exemplary embodiment of the invention in more detail. 
       In the drawings: 
         FIG.  1    shows a reflow soldering system in a side view obliquely from the front with a closed covering hood and closed hood flaps; 
         FIG.  2    shows the reflow soldering system according to  FIG.  1    in a front view with an open covering hood and open hood flaps; 
         FIG.  3    shows the reflow soldering system according to  FIG.  1    obliquely from the front with an open covering hood and open hood flaps; 
         FIG.  4    shows the reflow soldering system according to  FIG.  1    obliquely from the rear with an open covering hood and open hood flaps; 
         FIG.  5    shows the reflow soldering system according to  FIG.  1    obliquely from the front without machine paneling; 
         FIG.  6    shows an enlarged detail from  FIG.  5    with a drive unit; and 
         FIG.  7    shows the reflow soldering system according to  FIG.  1    obliquely from the front with a closed covering hood and open hood flaps. 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1    shows a reflow soldering system  10  for continuous soldering of a soldering item. The reflow soldering system  10  has an inlet  12  and an outlet  14 , wherein the material to be soldered reaches the reflow soldering system  10  via the inlet  12  and is discharged from the reflow soldering system  10  via the outlet  14 . The material to be soldered is transported along a transport direction  18  through a process channel  16  indicated in  FIG.  1   . 
     A preheating zone  20 , a soldering zone  22  and a cooling zone  24  are provided in the process channel  16 . In the reflow soldering system  10  shown in  FIG.  1   , a covering hood  25  having two hood flaps  26 ,  28  is provided for covering the hood chamber  30  enclosed by the covering hood  25 , in which chamber an upper channel half of the process channel  16  is located. 
     As is clear from  FIGS.  1  and  2   , a communication unit  36  is provided having a screen and an input device by means of which it is possible to communicate with a machine controller of the reflow soldering system  10 . 
     The soldering item, that is to say the printed circuit board provided with the solder paste and fitted with electronic components, is first heated in the preheating zone  20  to a temperature which is below the melting temperature of the solder paste. In the soldering zone  22 , the printed circuit board is heated for a certain duration to a process temperature which is above the melting point of the solder paste, so that said solder paste melts in the soldering zone in order to solder the electronic components to the printed circuit board. In the cooling zone  24 , the soldering item is cooled so that the liquid solder solidifies before the soldering item is removed at the outlet  14  of the reflow soldering system  10 . 
     A transport system  34  is provided within the reflow soldering system  10  for transporting the circuit boards along the transport direction  18 . 
     As is clear from  FIG.  2   , the covering hood  25  can be pivoted open about a hood axis  32  extending parallel to the transport direction  18 . By pivoting the covering hood  25  open, the interior of the process channel  16  and the transport system  34  are accessible in order to visually check, maintain, clean, set up, replace, and repair them if necessary. 
     As is further apparent from  FIG.  2   , the hood flaps  26  can be pivoted open about a flap axis  38  running parallel to the hood axis  32 . By pivoting the hood flaps  26 ,  28  open, the hood chamber  30  above the process channel and thus above the upper channel half is accessible, in which chamber, as is shown below, in particular fan modules, heating elements and air channels are provided. As is also clear from  FIG.  2   , the flap axis  38  is arranged vertically above the hood axis  32 , not only when the covering hood  25  is open, but also when the covering hood  25  is closed. 
     The soldering system  10  has two long sides  42  and  44  and two short sides  46  and  48 . As can be clearly seen in  FIG.  2   , the hood axis  32  is located in the region of the one rear long side  44 . In contrast, the flap axis  38  is located in the region of the front long side  42 , or is closer to the front long side  42  than to the rear long side  44 . 
     In  FIG.  3   , in which on the one hand the covering hood  25  and on the other hand the hood flaps  26 ,  28  are open, the open process channel  16  can be seen in particular. The process channel  16  is formed by two channel halves, an upper channel half and a lower channel half. The lower channel half with the lower nozzle plates  40  is provided in or on a main body  60  and the upper channel half with the upper nozzle plates  40  is provided in or on the covering hood  25 . The upper channel half, the upper nozzle plates  40  and further components located in the hood chamber  30  are arranged on the covering hood  25  such that, when the covering hood  25  is opened, they are also pivoted open and the process channel  16  is exposed. 
     Such an arrangement ensures that, as is clear from  FIGS.  2  to  4   , the process channel  16  is accessible from the front long side  42  when the covering hood  25  is open, and that the upper hood chamber  30  covered by the hood flaps  26 ,  28  is accessible from the other rear long side  44 . 
     Among other things, this has the advantage that, when the covering hood  25  is opened, and thus when the process channel  16  is exposed, gas flowing out of the process channel  16  does not flow into the upper hood chamber  30  covered by the cover flaps  26 ,  28 . Furthermore, a plurality of operators can simultaneously check or maintain the process channel  16  and, independently thereof, the hood chamber  30  covered by the cover flaps  26 ,  28 . 
     As is clear from  FIGS.  4 ,  5  and  7   , a plurality of fan modules  50  with fan motors  51 , which are provided for generating a provided air flow in the process channel  16 , is located above the upper channel half in the upper hood chamber  30  covered by the hood flaps  26 ,  28 . The fan modules  50  can additionally have heating elements in order to provide a predetermined temperature in particular in the preheating zone  20  and the process zone  22 . By means of the fan modules  50  or the fan motors  51  thereof, correspondingly heated air is introduced through the nozzle plates  40  into the process channel  16 . 
     If the covering hood  25  is opened, in particular the process channel  16  and the transport system provided therein are therefore accessible. If the hood flaps  26 ,  28  are folded out, in particular the fan modules  50  provided therein are accessible along with their heating elements as well as air channels provided there. 
     In their closed position, which is shown in  FIG.  1   , the two hood flaps  26 ,  28  have a horizontal section  52  which is located close to the flap axis  38  and extends substantially in the horizontal direction. This horizontal section is adjoined by an inclined section  56  which is remote from the flap axis  38  and forms an obtuse angle  54  with the horizontal section  50 . As is clear in particular from  FIG.  4   , handles  58  for opening the two hood flaps  26 ,  28  are provided on the inclined section. The obtuse angle  54  can be clearly seen in particular in  FIG.  2   . 
     The main body  60  stands on a substrate by means of feet  62 . The feet  62  are provided on a lower frame  64 . Furthermore, drive units  66  for the motorized opening and closing of the covering hood  25  are provided, and are supported at one end on the lower frame  64  and at the other end on the covering hood  25 . As is also clear from  FIG.  5   , which shows the covering hood  25  without paneling, the covering hood  25  comprises portal-type frame legs  68 , each of which has a first support section  70  directed toward the hood axis  32  and a second support section  72  directed toward the respective drive unit  66 . A central section  74  is provided in each case between the two support sections. 
     The central frame leg  68  is shown enlarged in  FIG.  6   . It is clear here that the drive unit  66  in each case comprises a motor  76  and a lifting element  78 . The motor  76  is arranged on the covering hood  25  or on the frame leg  68  thereof. The lifting element  78 , which can be displaced in the axial direction by the motor  76 , engages with its free end on the main body  60  and there on the lower frame  64 . By actuating the total of three drive units  66 , the covering hood  25  with the upper channel half and the further components can consequently be displaced between its closed position and open position. Because the motors  76  are each arranged on the hood side, they are also moved during opening and closing of the covering hood  25 . This arrangement has the advantage that no installation space has to be provided for the motors  76  in the region of the main body  60 . The installation space there can be used for other components, such as fan modules, cooling elements, condensate separators or the like provided on the main body  60 . 
     The motors  76  are preferably designed as electric motors and have a drive shaft along the axis  77 , which runs parallel to the transport direction  18  and parallel to the hood axis  32  and to the flap axis  38 . 
     The lifting elements  78  of the drive units  66  can in particular be designed as lifting rods or as spindle nuts which interact with a threaded spindle of the respective motor  76 , or can comprise such a lifting rod or spindle nut. 
     In order to compensate for a relative movement between the drive units  66 , the main body  64  and the frame legs  68  during movement of the covering hood  25 , the respective motor  76  is pivotable on the covering hood  25  or on the support section  72  about a compensation axis  80  running parallel to the hood axis  32 . Accordingly, the end of the associated lifting section  74  that faces away from the respective motor  76  is arranged so as to be pivotable to an extent about a compensation axis  82 , running parallel to the hood axis  32 , on the main body  60 . 
     In order to shield the motors  76  against heat, heat shields  83  are provided in the region of the process zone in the covering hood  25 . 
     As is clear in particular from  FIG.  6   , the frame legs  68 , and in particular their central sections  74 , have a vertical extension  84 . The arrangement is in this case such that the fan modules  50 , as is clear from  FIG.  5   , are provided in the vertical direction in the region between the upper side and the lower side of the frame legs  68 . 
     As is clear from  FIG.  7   , the hood chamber  30  and in particular the fan modules  50  are also easily accessible when the covering hood  25  is closed and only the hood flaps  26 ,  28  are opened.