Abstract:
A solder machine uses various linear actuators to move a PWB carrier in three degrees of freedom relative to a solder bath, to facilitate safe loading and unloading of PWBs onto the carrier while the carrier is distanced from the bath, and then to move the carrier over the bath, lower it, and tilt it as necessary to effect soldering.

Description:
FIELD OF THE INVENTION 
   The present invention relates generally to printed wiring board (PWB) soldering machines that dip, in two degrees of freedom, PWBs into a solder bath to effect soldering. 
   BACKGROUND OF THE INVENTION 
   Solder machines are used to dip components such as printed wiring boards into solder baths to effect mechanical-electrical connections. To undertake this dipping automatically, previous wave soldering systems have been used that have been relatively bulky to accommodate necessary conveyance of the PWBs into the solder bath at the desired locations of the PWBs. Furthermore, the bulkiness of the prior wave soldering machines has been necessitated to accommodate required soldering precision. Such prior machines have typically consumed around three square meters of valuable factory floor space. 
   SUMMARY OF THE INVENTION 
   A solder machine includes a solder bath and a frame juxtaposed with the solder bath and including a carrier configured for holding at least one component to be soldered. The carrier is movable in at least first, seconds and third degrees of freedom relative to the solder bath to solder the component. 
   In non-limiting embodiments the first degree of freedom is provided by tilting at least one edge of the carrier. The first degree of freedom can be provided by tilting a first edge of the carrier using a linear actuator coupled to the first edge. 
   A translational actuator may be provided to move the frame with carrier translationally in a horizontal plane to establish the second degree of freedom. The translational actuator can move the frame translationally in a horizontal plane between a load position, wherein the carrier is not over the solder bath to facilitate safe loading and unloading of components therefrom, and a solder position, wherein the carrier is over the bath to facilitate soldering. Furthermore, four raise/lower actuators may be provided to raise and lower the carrier along a vertical axis when in the solder position. 
   In another aspect, a method of soldering at least one printed wiring board (PWB) includes moving a PWB carrier in three degrees of freedom relative to a solder bath to facilitate safe loading and unloading of PWBs onto the carrier while the carrier is distanced from the bath, and to move the carrier over the bath, lower it, and tilt it as necessary to effect soldering. 
   In still another aspect, a solder machine includes a base holding a solder bath and a carrier support coupled to the base and movable along a vertical axis toward and away from the solder bath. A carrier frame is slidably engaged with the carrier support and can be moved in a horizontal plane toward and away from the solder bath. A PWB carrier configured for holding at least one PWB to be soldered can be tilted relative to the carrier frame from a horizontal plane. 
   The details of the present invention, both as to its structure and operation, can best be understood in reference to the accompanying drawings, in which like reference numerals refer to like parts, and in which: 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of the present solder machine, showing PWBs on the top carrier; 
       FIG. 2  is a perspective view of the present solder machine with slide piston for moving the PWB carrier in the first degree of freedom and raise/lower pistons for moving the carrier base in the second degree of freedom, showing the PWB carrier and carrier base exploded away from the solder bath for clarity and with portions of the machine removed for clarity, with the PWB carrier in the load position and the carrier support in the raised position relative to the solder bath; and 
       FIG. 3  is a perspective view of the tilt mechanism that pivots the carrier in the third degree of freedom. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Terms of height such as “top”, “bottom”, “above”, “below”, “upper”, “lower”, “higher”, “lower”, etc. as used herein are relative to the soldering machine when it is positioned on the floor of an assembly plant as intended. 
   Referring initially to  FIG. 1 , a solder machine is shown, generally designated  10 , which includes a shroud or housing  12  enclosing a frame  14  that is coupled to a solder bath  16  holding solder for dip-soldering components such as printed wiring boards (PWB)  18 . The solder machine  10  may support a processor  20  (shown schematically in  FIG. 1 ) that controls motion of the frame in accordance with disclosure below. The processor  20  may output information on a computer monitor  22  if desired. 
   Details of the frame  14  and how it moves with three degrees of freedom relative to the (non-moving) solder bath  16  can be seen in cross-reference to  FIG. 2 . The frame  14  includes a top flat generally rectilinear PWB carrier  24  which includes support structure  26  for supporting one or more PWBs. The PWBs may plug into the support structure  26  or may rest on it or be clamped or otherwise held by the support structure  26 . It is to be appreciated that parts of the PWBs to be soldered extend below a central cavity  28  defined by the carrier  24  and toward the solder bath below, so that as the carrier  24  is moved in accordance with disclosure below the portions of the PWBs are dipped into molten solder. 
   The PWB carrier  24  is pivotably coupled to a hollow rectilinear carrier frame portion  30  that surrounds the PWB carrier  24 . Specifically, the carrier frame portion  30  has sides  32 ,  34  that are distanced from adjacent sides of the PWB carrier  24  and a solder bath edge  36  that is pivotably coupled to a solder bath edge  38  of the PWB carrier  24 , such that the PWB carrier  24  can pivot relative to the carrier frame portion  30  about the solder bath edge  38  as indicated by the arrows  40 . In other words, when the structure described below pivots the PWB carrier  24 , the edge  42  of the PWB carrier  24  that is opposite the solder bath edge raises (in one direction of the pivot) and lowers (in the other direction of the pivot) relative to the carrier frame portion  30 . 
   As briefly described above, in  FIG. 2  the PWB carrier  24  is in a load position and a hollow generally rectilinear carrier support  44  is in a raised position relative to the solder bath. It is to be appreciated that the carrier frame portion  30  is slidably engaged with the carrier support  44 . 
   With more specificity, in  FIG. 2  the PWB carrier  24  is distanced in the horizontal dimension from the solder bath  16 , so that PWBs can be loaded on and unloaded off the PWB carrier  24  by a person while the PWB carrier  24  is relatively safely distanced from the solder bath. When the PWBs have been loaded on to the PWB carrier  24 , a translational linear actuator  48  that is coupled to the carrier frame portion  30  is actuated to translationally move the carrier frame portion  30  with PWB carrier  24  in the horizontal plane in the direction indicated by the arrow  48  to a solder position, in which the carrier frame portion  30  is surrounded by the carrier support  44  and in which the PWB carrier  24  is juxtaposed with the solder bath  16 . 
   As can be appreciated in reference to  FIG. 2 , four raise/lower linear actuators  50  couple respective corner areas of a solder bath base  52  to the carrier support  44 . Specifically, respective flat top pads  54  of the raise/lower actuators  50  can engage respective corner flanges  56  of the carrier support  44  such that when the raise/lower actuators  50  are activated, they can move the carrier support  44  down along the vertical axis as indicated by the arrows  58  toward the solder bath  16  to a lowered position, and then back tip again to the raised position shown in  FIG. 2 . In some embodiments pivotable motion between the raise/lower actuators  50  and flanges  56  may be provided for so that, e.g. two of the four actuators  50  may be actuated to tilt the carrier support  44  relative to the solder bath  16 . In the embodiment shown in  FIG. 2 , however, all four raise/lower actuators  50  work in concert to raise and lower the carrier support  44  while the support  44  remains substantially flat in the horizontal plane. 
   With the PWB carrier  24  in the solder position and the carrier support  44  in the lowered position, as mentioned above the PWB carrier  24  can pivot relative to the carrier frame portion  30  about the solder bath edge  38  as indicated by the arrows  40 . In one non-limiting implementation this pivoting may be effected by a pivot arm  60 , shown in  FIG. 2  and best shown in  FIG. 3 , which will now be referenced. As shown, the pivot arm  60  has a free end which may be coupled to a rubber or plastic cylindrical grommet-like pad  62 . The pad  62  contacts the bottom of one of the sides of the PWB support  24  when the apparatus is in the solder, lowered position. The opposite end  63  of the pivot arm  60  is coupled through, e.g., a hall screw coupling  64  to a stepper motor  66  to pivot the arm  60  between the vertical orientation shown toward a horizontal orientation. It will readily be appreciated that this pivoting motion causes the pad  62  and, hence, the side of the PWB carrier  24  to which it is coupled to raise and lower as desired, which tilts the PWB carrier  24  as described. 
   The operation of the solder machine may now be appreciated. To load a PWB onto the PWB carrier  24 , the carrier support  44  is raised and the carrier frame slid away from the solder bath to the load position of  FIG. 2 . An operator can safely load PWBs onto the PWB carrier  24  with minimal exposure to the solder bath. Then, the translation actuator is activated to pull the carrier frame  30  within the carrier support  30 , over the solder bath. The raise/lower actuators are next activated to lower the carrier support  44  toward the solder bath, and then the tilt actuator with pivot arm  60  activated to tilt the PWB carrier  24  as appropriate for the soldering sought to be effected. At the completion of soldering the above operations are reversed to permit the operator to safely offload soldered PWBs. 
   While the particular SELECTIVE SOLDERING SYSTEM is herein shown and described in detail, it is to be understood that the subject matter which is encompassed by the present invention is limited only by the claims. For example, pistons may be used but other linear actuators such as rack-and-pinion style actuators driven by, e.g., stepper motors may be used.