Abstract:
A method of and device for applying a liquid coating to the threads and only the bearing face of a threaded nut and the resulting coated nut are provided. The method includes providing a pumping mechanism that has a container containing the liquid lubricant and a pumping mechanism connected with the container. The pumping mechanism includes a liquid ejecting device having an actuatable delivery mechanism. A foraminous pad supports the face of a nut that is to have liquid lubricant applied thereto. A nut to be coated with the lubricant is placed on the foraminous pad and thereafter the delivery mechanism is actuated to eject liquid onto the threads and the foraminous pad to provide a nut which has coating on only the threads and on the bearing surface or face.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This invention relates generally to applying a lubricant to nut threads and the resulting product and, more particularly, to a method of applying a wax and dye coating only to the threads of a nut and to one face thereof while maintaining the remainder of the nut free of the wax and dye.  
           [0003]    2. Background Information  
           [0004]    In certain applications of threaded nuts, particularly in their use in connecting various bridge elements together, nuts are threaded onto bolts to hold the elements of the bridge in place. These are typically very large bolts and nuts and it is required that they be torqued down to a rather high torque to assure reliable connections. Because of their relatively large size and frictional resistance, it is somewhat difficult to achieve the high torque necessary to assure this reliable connection. Therefore, it is desirable to provide some kind of lubricant, particularly to the threads, and also preferably to the bearing face of the nut, to allow or permit the torquing to be done more easily. However, conventional lubricants, such as wax or wax and dye which are conventionally specified as lubricants, are repellant to paint and, thus, the exposed surfaces of the nut, i.e. the torquing surfaces and the free surface of the nut, must be maintained clear of the lubricant if the bridge structure is to be painted. It is thus desirable to provide a technique for supplying a selectively coated nut, as well as a process and device for coating the threads and the bearing surface or face of the nut with a lubricant, such as a wax and dye, while maintaining the other surfaces free of such lubricant.  
         SUMMARY OF THE INVENTION  
         [0005]    According to the present invention, a method of and device for applying a liquid coating to the threads and only the bearing face of a threaded nut and the resulting coated nut are provided. The method includes providing a pumping mechanism that has a container to receive the liquid lubricant to be applied and a pumping mechanism connected with the container. The pumping mechanism includes a liquid ejecting device connected with the container, including an actuatable delivery mechanism communicating with the container. A foraminous pad is disposed to support the face of a nut that is to have liquid lubricant applied thereto. The delivery mechanism, upon actuation, will dispense the liquid only on the threads of the nut on the foraminous pad. A nut to be coated with the lubricant is placed on the foraminous pad and thereafter the delivery mechanism is actuated to eject the liquid onto the threads and the foraminous pad to thereby provide a nut which has coating on only the threads and on the bearing surface or face that is to be engaged with a member being connected. 
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0006]    [0006]FIG. 1 is a sectional view of a galvanized, threaded nut which has been coated with a lubricant, according to the present invention, on the threads and bearing surface only thereof;  
         [0007]    [0007]FIG. 2 is a longitudinal, sectional view of a device for applying a coating to the threads and bearing surface of a nut in an unactuated condition; and  
         [0008]    [0008]FIG. 3 is a view similar to FIG. 2 of the device in the actuated condition. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0009]    Referring now to the drawings, and for the present to FIG. 1, a threaded, galvanized nut N having been coated with a wax and dye lubricant W/D according to this invention is shown. The nut N includes internal threads T having a bearing face BF and a free face FF. The threads T and bearing face BF have had applied thereto a wax and dye W/D coating according to a method which will be described presently. The wax and dye coating W/D is a wax lubricant with a dye disposed therein. Preferably, this is Castrol Safety Film 639 manufactured by Castrol Industrial Great Lakes, Inc. It is to be understood that this particular wax and dye W/D is illustrative only, but it is preferred since this is the wax and dye that is specified for many applications of nuts in the bridge construction industry.  
         [0010]    Referring now to FIGS. 2 and 3, a mechanism for coating only the threads T and the bearing face BF of the nut, while allowing the free face FF, as well as torquing or tightening faces TF of the nut N, to remain uncoated, is provided.  
         [0011]    The coating mechanism includes a container  10  having the wax and dye W/D disposed therein. As indicated above, the wax and dye preferably is Castrol Safety Film 639 and, in condition to be sprayed when in the container  10 , has a viscosity which approximates that of water at ambient temperature. The device includes a pumping mechanism designated generally as  14  which includes a hollow fill tube  16  which extends into the container  10  and is secured thereto by a collar  17  which is connected to the container  10  by means of a cam member  18 , a roller  19  and pin  20  mounted on the collar  17  and engaging camming surface  21  on cam member  18 , thus allowing the pumping mechanism  14  to be removed to fill the container  10  with wax and dye W/D. The hollow fill tube has fluid inlet openings  22  at the distal end and air escape openings  23  adjacent the collar  17 .  
         [0012]    A hollow ejection tube  24  is provided which extends through the collar  17  and terminates in a piston ring  25  in sealing relationship with the hollow fill tube  16  between the inlet openings  22  and air escape openings  23 . A holding tray  26  is welded to the end of hollow fill tube  16  and a spring  28  is interposed between the holding tray  26  and the collar  17 . A hollow extension tube  30  is provided which threadably engages internal threads  32  of the hollow ejection tube  24 . A cup-shaped support member  34  is welded to the hollow extension tube  30  and a foraminous pad  36  is disposed in the support member  34 . The foraminous pad  36  preferably is formed of a disc of Scotchbrite material manufactured and sold by 3M Corporation. However, other material, such as felt, may be used. Support member  34  has holes  38  therein which allow liquid to drain from the support member  34  into the holding tray  26 .  
         [0013]    The distal end of the hollow extension tube  30  is threaded as at  40  and a jamb nut  42  is threaded onto the threaded portion  40 . An annular shield  44 , which preferably is also made of Scotchbrite (or other material, such as felt could be used) and which has a diameter slightly larger than the internal diameter of the nut to be coated, is provided over the threaded end  40  of the hollow extension tube  30  abutting the jamb nut  42 . A thumb nut  45  is threaded onto threads  40  and captures the shield  44  between it and thumb nut  42 . A cap nut  46  is threaded on threads  40  to close the end of hollow extension tube  30 . The hollow extension tube  30  is provided with a series of circumferentially spaced orifices  48  from which the wax and dye W/D is ejected upon actuation, as will be described presently.  
         [0014]    A drain member  50  is provided which resides in the holding tray  26 , the drain member  50  having drain holes  52  therein to allow the liquid which drains from the support member  34  to drain into the holding tray  26 . A drain orifice  54  is provided in the hollow ejection tube  24  to allow the drained fluid in the holding tray  26  to drain back down through the hollow ejection tube  24  into the hollow fill tube  16  and thence into the container  10 .  
         [0015]    The operation of the device for coating a threaded nut is as follows: a nut N to be coated is placed over the hollow extension tube  30 , which extension tube  30  extends through the central opening in the nut so that the bearing face BF of the nut is against the foraminous pad  36 , and the annular shield  44  is disposed at the end of the threaded portion T of the nut, as shown in FIG. 2. A downward pressure is applied to the nut to actuate the coating device by moving it from the position shown in FIG. 2 to that shown in FIG. 3. As shown in FIG. 3, the pumping mechanism  14  will be actuated, which will move the hollow ejection tube  24  and hollow extension tube  30  and piston ring  25  downwardly in the hollow fill tube  16  against the bias of spring  28 . The downward pressure will cause the liquid contained in the hollow fill tube  16  to be forced up through hollow ejection tube  24  and hollow extension tube  30  and be ejected through the orifices  48 . Also, some liquid will be ejected through orifices  54  but this does not matter since enough liquid to coat the threads and soak the pad  36  will be ejected from orifices  48 . It is also to be understood that there will be some pressure to eject the fluid from the inlet openings  22 ; however, since there is liquid wax W/D in the container, the action will be against a greater fluid head than at escape openings  22  and orifices  48  which are exposed only to air. Thus, there is minimal fluid flow through openings  20 . The result is that sufficient liquid W/D is expelled through orifices  48  to coat the threads T and soak the pad  36  to coat the bearing face BF of the nut N. This ejection of the wax and dye W/D from the orifices  48  wll spray the wax and dye W/D onto the threads T of the nut N and also onto the foraminous pad  36 . Also, excess wax and dye W/D from the threads T will also leak onto the pad  36 . The sprayed wax and dye W/D from the orifices  48  will coat the threads T of the nut N, and the wax and dye W/D in the foraminous pad  36  will coat the bearing face BF of the nut N with the wax and dye W/D. However, the annular shield  44  will prevent the wax and dye W/D from spraying out through the end of the nut and confine the coating only to the threads T and to the foraminous pad  36 . Thus, the free face FF and torque face TF of the nut N are maintained free of the wax and dye W/D.  
         [0016]    When the pumping mechanism  14  has been completely actuated, as shown n FIG. 3, pressure on the nut is relieved, allowing the spring  28  to return the pumping mechanism  14  to the position shown in FIG. 2. Upon return to the position shown in FIG. 2, a vacuum will be created within the hollow extension tube  30  and the hollow ejection tube  24  and, thus, the air pressure on the surface of the wax and dye W/D in the container  10  will force the wax and dye W/D through opening  22  up into the tubes  24  and  30  to refill the tubes ready for the next actuation.  
         [0017]    As the foraminous pad  36  becomes saturated, the excess wax and dye W/D in the foraminous pad  36  will drain through openings  38  and  52  into the holding tray  28  and thence through drain orifice  54  into the ejecting tube  24 . The nut N is then removed, and the shield  44  will wipe away any excess wax and dye W/D from the threads T. Once applied, the wax and dye W/D will solidify on the threads T and bearing face BF to form a lubricant film.  
         [0018]    A vacuum or other technique may be used to partially or fully dry the wax and dye W/D coating. This prevents the bearing face BF of the nut from sticking to any surface, such as packing material on which it may be supported after coating.  
         [0019]    The foraminous pad  36  and annular shield  44  can be replaced as often as necessary. Also, the space between the annular shield  44  and the foraminous pad  36 , which constitutes the thickness of the nut, can be changed by altering the position of the jamb nut  42  which locates the bottom of the annular shield  44  with respect to the nut end being coated. Moreover, the diameter of the annular shield  44  can be changed to accommodate other diameter nuts N. Also, it is to be understood that, if desired, either permanent or adjustable stop members could be provided, for example, on the holding tray  26  or on the tube  24  to restrict the length of movement on the actuating movement of the pumping mechanism  14 .  
         [0020]    Accordingly, the preferred embodiments of the present invention have been described. With the foregoing description in mind, however, it is understood that this description is made only by way of example, that the invention is not limited to the particular embodiments described herein, and that various rearrangements, modifications, and substitutions may be implemented without departing from the true spirit of the invention as hereinafter claimed.