Abstract:
The invention is directed to a nozzle for a hot air device used in the electronic assembly industry to melt solder or heat shrink-wrap insulators. The nozzle provides a uniform temperature environment and suppresses the occurrence of local excess heating.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a nozzle for a hot air device used in the electronic assembly industry to melt solder or heat shrink-wrap insulators. The nozzle provides a uniform temperature environment and suppresses the occurrence of local excess heating. 
       BACKGROUND OF THE INVENTION 
       [0002]    In the electronics fabrication and re-working field, a hot air device is often used to melt solder when a user is required to dismount or remove and replace an electrical component. Hot air may also be used to heat shrink-wrap insulation materials. However, when hot air is blown on a targeted electronic device directly, the thermal energy may be undesirably transmitted to other electronic elements adjoining the targeted device. This inadvertent heat transfer occurs with contemporary nozzles because the nozzles are held above or floated over a substrate and the targeted device, and the hot air must exhaust via the space between the nozzle and the substrate. When the user wants to prevent thermal energy from transferring heat undesirably to adjacent components from a space between the nozzle and the substrate, the conventional nozzles have complicated structures. For example, some conventional nozzles have air flow exhaust passages in the nozzle. Conventional nozzles with complicated structures tend to be unsuitable for high density mounted PCB components due to their size. Reducing the size of conventional nozzles with complicated structures is expensive. 
       BRIEF DESCRIPTION OF THE PRESENT INVENTION 
       [0003]    The present invention details a nozzle design and production method for the nozzle to provide a simple structure for a hot air nozzle having an exhaust path that protects against heat transfer to surrounding electrical components. The nozzle is configured to be mounted on the distal end of a heating device, such as a hand held hot air device connected to a work station. The hot air nozzle provides a uniform temperature environment while suppressing the occurrence of local excess heating. A heated electrical component or object can receive thermal energy by hot air effectively and efficiently, and most of the hot air is exhausted through exhaust holes in the nozzle. There is no complicated structure in the nozzle. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0004]      FIG. 1  is a perspective view of a hot air device including a nozzle according to the present invention. 
           [0005]      FIG. 2  is a side view of the nozzle of  FIG. 1  and the present invention. 
           [0006]      FIG. 3  is a perspective, cut away view of the nozzle of the present invention. 
           [0007]      FIG. 4  is an end view of the component to fabricate into the convection box of the nozzle. 
           [0008]      FIG. 5  is a perspective view of the convection box of the nozzle. 
           [0009]      FIG. 6  is a perspective view of the final configuration of the nozzle. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0010]      FIG. 1  shows a perspective view of an exemplary hand-piece portion of a hot air blower  10 . The hot air blower  10  includes a handle section  12  connected at a proximal end to a cable  14  extending to a control box (not shown). The handle section  12  includes an insulated grip  16  as well as a switch  18  and control knob  20 . Switch  18  controls the flow of air from the hot air blower  10 . Control knob  20  may be used to control the application of a vacuum. The handle section  12  of the hot air blower  10  also includes a blowout cylinder  22  at the distal end, which encloses the heating element. The blowout cylinder is a metallic element having at least one projecting bump  24 . 
         [0011]      FIG. 1  also depicts the hot air nozzle  30  of the present invention secured to the distal end of the blowout cylinder  22  of the handle section  12  of the hot air blower  10 . The hot air nozzle  30  comprises a convection box  32  having corner supports or brace plates  34 . The convection box  32  is attached to and extends from a connection cylinder  36  that extends from a baffle plate  38 . The baffle plate  38  is secured to an insertion cylinder  40 , sized to have an internal diameter that fits snuggly over the distal end of the blowout cylinder  22  of the handle section  12 . The insertion cylinder  40  includes at least one J-shaped curved groove  42 , configured to accommodate the at least one projecting bump  24  of the blowout cylinder  22 , to secure the hot air nozzle  30  to the handle section  12 , as shown in  FIG. 1 . 
         [0012]      FIG. 2  is a side view and  FIG. 3  is a perspective, cut away view of the hot air nozzle  30  of  FIG. 1 , and accordingly the same reference numbers are included for the components of the hot air nozzle  30 . The perspective, cut away view of  FIG. 3  depicts additional details of the convection box  32  and the connection cylinder  36 . As depicted, the convection box  32  includes an end wall  50  and four side walls  52 . The end wall  50  has a large axial orifice  54  as well as spaced apart exhaust ports  56  that are preferably symmetrically placed with respect to said orifice  54 . 
         [0013]    As it may be seen from the cross section of  FIG. 3 , the connection cylinder  36  connecting the convection box  32  and the insertion cylinder  40 , is made from an outer cylinder  60  and an inner cylinder  62  that projects into the outer cylinder  60 . By this structure, the hot air passing through the connection cylinder  36  provides uniform heating in the convection box. The outer cylinder  60  is preferably made from the same piece as, or a flange of, the end wall  50  of the convection box  32  by a burring process. The inner cylinder  62  is preferably made from the same piece as, or a flange of, the baffle plate  38 . The inner cylinder  62  may be formed by a deep drawing or stamping of a metal plate forming a cylindrical cup shape. As a result of the forming process, the open end of the cup shaped inner cylinder  62  faces the air flow-in area of the blowout cylinder  22  of the handle section  12  when the nozzle  30  is attached to the handle  12 . The end or bottom of the cup shaped inner cylinder  62  formed by the deep drawn or stamping process is drilled or cut to form at least one hole  64 , and preferably a plurality of orifices or holes  66 , which provide the openings for the passage of hot air from the handle  12  ( FIG. 1 ) to the convection box  32 . Alternatively the inner cylinder may also be made by a burring process, configuring a single big hole for the hot air to blow in. 
         [0014]    The connection cylinder  36  is formed by inserting the inner cylinder  62  into the outer cylinder  60 . The inner cylinder  62  and the outer cylinder  60  may be integrated by welding or press fitting. Alternatively, the inner cylinder  62  and the outer cylinder  60  may be made detachable, so that convection boxes  32  having various sizes and shapes may be used with a common insertion cylinder  40  and baffle plate  38 . Preferably, the hot air nozzle  30  is made in three pieces, the convection box  32  including the outer cylinder  60 , the baffle plate  38  including the inner cylinder  62 , and the insertion cylinder  40 . It should be noted that while the convection box  32  depicted and described herein is formed in the shape of an open-ended cube, the convection box  32  may be formed to define other shapes, including cylinders and elongated rectangles configured to fit over the various shapes of electrical circuit components. 
         [0015]    To illustrate the fabrication process,  FIG. 4  is an end view of the component to fabricate into the convection box of the nozzle of the present invention.  FIG. 4  shows a metal plate, formed for example from stainless steel or aluminum, to be fabricated to make the convection box  32 . The convention box is made by bending. Four dotted lines in  FIG. 4  identify the lines along which the four side walls  52  are bent ninety degrees to the end wall  50 . The cross-shaped metal plate is fabricated by punching press or a metal cutting machine. The large axial orifice  54  as well as the spaced apart exhaust ports  56  are formed during the punch press or cutting process before the sidewalls  52  are bent to the final shape depicted in the perspective view of the convection box  32  of the nozzle  30  depicted in  FIG. 5 . 
         [0016]      FIGS. 4 and 5  depict the convection box  32  with the end or bottom of the cup shaped inner cylinder  62  inserted into the axial orifice  54  formed in the end wall  50 . However, in an alternative construction to the configuration described with respect to  FIGS. 2 and 3 , the end wall  50  of the convection box  32  may be configured to include the least one hole  64 , and preferably the plurality of orifices or holes  66  shown in  FIGS. 4 and 5 , in which case the connection cylinder  36  is simply a cylinder attached at one end to the baffle plate  38  and at the other end to the end wall  50 . 
         [0017]      FIG. 6  is a perspective view of the final configuration of the hot air nozzle  30  of the present invention. After the side walls  52  are bent to their final shape, corner supports or brace plates  34  may be secured to, for example by welding, spot welding, or fasteners (not shown), to the edges of the convection box  32  to both strengthen the convection box  32  and reduce air leakage at the seams. 
         [0018]    The spacing between the opposing faces of the end wall  50  of the convection box  32  and the baffle plate  38  created by the length of the connection cylinder  36  allows the heated air to exhaust from the convection box  32  through the exhaust ports  56  and the exhausting hot air flow impinges on the baffle plate  38  and is thereby deflected radially outward so as to avoid injuring the user&#39;s hand holding the handle section  12  at the insulated grip  16 . Preferably, the baffle plate  38  is slightly larger than the end wall  50 . Due to the height of the side walls  52 , the hot air is exhausted sufficiently above the work surface and the electrical components mounted thereupon to avoid damaging the surrounding circuitry. 
         [0019]    In operation, the convection box  32  defines a convection space. The convection box  32  is placed over the surface of the substrate to be heated with the distal edges of the side walls abutting the surface of the substrate, for example a printed circuit board (PCB), and the peripheral side walls  52  prevent the hot air from flowing onto surrounding electric components. The shape of the end wall  50  is preferably the same as the shape defined by the distal edges of the side walls. Hot air enters the convection box  32  via the holes  64  and  66 . The hot air is convected in the convection space exhausting through the exhaust ports  56 . Therefore, electronic components adjoining the targeted component are not exposed to thermal energy of the hot air. Hot air from the hole is convected in the convention space and the thermal energy is transmitted to the targeted element properly. 
         [0020]    The convection space in the convection box  32  extends from the holes  64  and  66  to the peripheral side walls  52  and the surface of the workpiece. As a result, hot air provides thermal energy to the targeted electronic component uniformly without causing excessive low temperature or high temperature locally. The user can dismount electrical components with high reliability. 
         [0021]    To transmit thermal energy to a heated object such as a solder connection, an electronic element or a substrate, it is preferable to circulate hot air uniformly inside a nozzle&#39;s convection box. The present invention provides a convection box having a simple structure which can convect hot air in a confined space bounding the object to be heated. Those skilled in the art will readily appreciate that the disclosure herein is meant to be exemplary and actual parameters, shapes and materials depend upon the specific application for which the present invention is intended. The foregoing embodiments are presented by way of example while the scope of the invention is defined by the appended claims and equivalents thereto.