Patent Publication Number: US-7210382-B2

Title: Screw guide device

Description:
BACKGROUND OF THE INVENTION 
   The present invention is directed to devices to aid in the insertion of fasteners into materials. 
   It is often desirable to insert a fastener, such as a screw, a known or predetermined depth into a material. Inserting the screw a known depth into a material can be a critical evolution when it is important to avoid inserting the screw too deep into a material, i.e. to avoid the screw from extending through the opposite side of the material when it is thinner than the length of the screw, or to avoid inserting the screw too deep in the material to prevent the material from fracturing if the material is brittle and the screw extends through a majority of the depth of the material. Additionally, it is often desirable to insert a screw into a material such that the screw head does not contact the material surface that the screw is extended into, i.e. when the screw head is at a “stand off height” from the material surface. In addition to inserting a screw into a material with a stand off height it is often critical that multiple screws of the same length be inserted into a material with each having the same stand off height above the material surface. 
   It is desirable to provide a screw guide device with an improved design to insert a screw a predetermined depth into a material and provide a mechanism to establish a repeatable screw head stand off height. 
   SUMMARY 
   Accordingly, a screw guide device is provided to insert screws a set depth into a material and to establish a predetermined and repeatable stand off height. In general, the screw guide device of the present invention contains a cylindrical member with a first and a second end that is rotatably engaged with a stop ring. A sleeve surrounds the cylindrical member and the stop ring. A stand off ring is engaged with the cylindrical member between the sleeve and a second end of the cylindrical member. The cylindrical member is adapted to receive the torque from an external source on the second end of the cylindrical member and transfer the torque to a screw that can be engaged by the first end of the cylindrical member. As torque is applied to the cylindrical member, the sleeve translates along the longitudinal axis of the cylindrical member until it contacts the stand off ring, which prevents further insertion of the screw. 
   A method for setting screw head stand off height is provided. Before using the screw guide device, the user adjusts the initial position of the sleeve with the stop ring to position it to the length of the screw to be used and also adjusts the stand off ring to set a stand off height of the screw. The user engages an external device to provide torque to the cylindrical member to drive the screw. The cylindrical member will drive the screw the preset distance and establish the preset stand off height based on the position of the stand off ring. After use, the sleeve slides towards the working portion of the tool until it contacts the forward stop ring that is preset to accommodate the length of the screw to be used. This allows the user to insert into the material another screw of the same length into the material and establish the same stand off height. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of one embodiment of the screw guide device of the present invention; 
       FIG. 2  is an exploded view of the device of  FIG. 1 ; 
       FIG. 3  is a cross-sectional view of the device of  FIG. 1 . 
       FIG. 4  is an exploded view of the components used to form the cylindrical member of the screw guide device of  FIG. 1 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   As shown in  FIGS. 1–3 , a screw guide  10  used to insert a standard screw (not shown) to a specific screw depth and set a standard screw head “stand off” height from a work surface (not shown) is provided. The embodiments contained herein specifically describe and illustrate the use of the screw guide  10  in combination with a screw, but the screw guide  10  may also be fitted for use with other types of fasteners such as bolts that are driven into a material by rotating them with sufficient torque. In addition, for ease of reference in the following description, the fastener will be referred to as a screw. This reference is not meant to limit the scope of the invention. 
   The screw guide  10  contains a cylindrical member  20  that is adapted to receive torque produced by an external source (not shown) and to transmit the torque to a screw or other type of fastener using a machined removable tip  24 . The cylindrical member  20  is preferably made from steel. The cylindrical member  20  has a first end  21 , a second end  22 , and a threaded section  28  disposed between them. The screw guide also contains a stop ring  40  that travels along the threaded section  28  of the cylindrical member, a sleeve  60  that surrounds the stop ring, and a stand off ring  80  that also travels along the threaded section  28  of the cylindrical member and is located between the sleeve  60  and the second end  22  of the cylindrical member. 
   A working portion  25   a  of the removable tip  24  is formed in the shape opposite of the torque receiving structure, i.e., the fastener, and is similar to tips that are used with electric drills or screwdrivers that are known in the art. Although a removable tip  24  for use with a Phillips head screw is shown in the figures, removable tips  24  for use with flat head screws, or other types fasteners, such as bolts can be used. The removable tip  24  for use with the screw guide  10  may be made from a ferromagnetic material, as is known. 
   As best shown in  FIG. 3 , the removable tip  24  is inserted into the front section  26  of the cylindrical member  20 . The front section  26  includes an aperture  26   a  at the front end  21  of the cylindrical member that is hollow and has an internal diameter to allow the removable tip  24  to fit snuggly within the front section  26 . The front section  26  has the same general length as the shaft portion  25  of the removable tip  24 . As a result, the working portion  25   a  of the removable tip  24  extends outside of or beyond the front section  26  to allow the working portion  25   a  to engage the screw head. 
   A magnet  27  may be provided at the rear portion of the front section  26  to help maintain the removable tip  24  inserted into the front section  26 , but to allow the user to extract the removable tip  24  from the cylindrical member  20  when desired. In one embodiment, the front section  26  is formed with a hexagonal profile to maintain a tight fit between the front section and removable tips  24  that have a hexagonal shaped shaft portion  25 . In other preferred embodiments, the internal surface of the front section  26  may be round or some other suitable shape. 
   A threaded section  28  with external threads  29  is between the front section  26  and the shank  30 . The length of the threaded section  28  must be at least as long as the length of the longest screw that the screw device  10  is designed to used with in addition to the combined widths of the stop ring  40  and the stand off ring  80 . 
   Further along the cylindrical member  20  there is a blind hole  35  on the end of the threaded section  28  closest to the second end  22  of the cylindrical member as is shown in  FIG. 4 . The blind hole  35  is sized to receive a post  33  from a shank  30  that forms the second end  22  of the cylindrical member  20  when it is mated with the rest of the cylindrical member  20 . A stop washer  36  is located on the post  33  when the post  33  is inserted into the blind hole  35 . The stop washer  36  serves to maintain the post  33  inserted into the blind hole  35 , and, in a preferred embodiment, sets the default position of the stand off ring  80 , as will be discussed below. Alternatively, the cylindrical member  20  can be fashioned from a single piece. 
   The shank  30  is sized and shaped to be inserted into the chuck of a drill (not shown) or other tool to transfer torque to the cylindrical member  20  that rotates along with the chuck when so engaged. In the preferred embodiment shown in  FIG. 1 , the shank  30  contains a rear polygonal section  31  to allow the chuck to rotatably hold the cylindrical member  20  as well as a recess element  32  designed to be engaged by detent balls (not shown) in a quick release chuck (not shown) for rotatably holding the cylindrical member  20  in a quick release drill chuck. 
   As best shown in  FIG. 3 , the screw guide device also includes a hollow stop ring  40  with internal threads  42  corresponding to the external threads  29  of the cylindrical member  20 . The stop ring  40  is preferably made from nylon but other types of plastic or metals such as steel or brass can be used. The stop ring  40  has a surface wide enough for the user to rotate it with respect to the cylindrical member  20 , and additionally is wide enough to have a sufficient number of internal threads  42  to provide a durable rotational connection between the stop ring  40  and the external threads  29  of the cylindrical member  20 . The outer surface  41  of the stop ring  40  is formed with a straight knurl  44  to provide the user with a surface that can be rotated against the frictional forces that will oppose rotation of the stop ring  40 . 
   A sleeve  60  surrounds most of the longitudinal length of the cylindrical member  20 . The sleeve may be made from steel or brass with a nylon overmold, but other materials with acceptable characteristics can be used. The sleeve  60  has a tip end  61  that is closest to the removable tip  24  of the cylindrical member  20  when the sleeve  60  surrounds the cylindrical member  20  and a chuck end  62  that is closest to the second end  22 . The sleeve  60  is a long hollow tube with an inside diameter slightly larger than the outside diameter of the stop ring  40  to allow for easy movement along the longitudinal axis of the cylindrical member  20 , but a close enough fit to minimize the size of foreign objects or particles that can get between the sleeve  60  and the cylindrical member  20 . 
   The sleeve  60  contains an aperture  68  in the grip section  70  near the chuck end  62 . The aperture  68  is slightly wider than the width of the stop ring  40 . The chuck end  62  of the sleeve  60  contains an inner diameter slightly smaller than the outer diameter of the stop ring  40  such that the stop ring  40  creates a barrier from the sleeve  60  moving any further towards the first end  21  of the cylindrical member  20  than the position where the chuck end  62  of the sleeve makes contact with the stop ring  40 . 
   As shown in  FIGS. 1 and 2 , the sleeve  60  also includes a longitudinal slot  66  along the longitudinal axis of the sleeve  60  between the aperture  8  and the tip end  61  of the sleeve. The slot  66  allows the viewer to view the cylindrical member  20  as the sleeve  60  translates along the longitudinal axis of the cylindrical member  20 . The slot  68  may include a translucent cover to prevent entry of foreign materials or particles into the screw guide  10 . The sleeve  60  also includes depth markings  67  (a scale) that are calibrated to allow the user to set the screw guide  10  for the length of screw to be used with the screw guide  10 . 
   The slot  66  is calibrated in the following manner. The user holds the sleeve  60  such that the ledge  69  of the sleeve  60  contacts the stop ring  40 . The user views the slot  66  and rotates the stop ring  40  until the edge between the front section  26  and the threaded section  28  corresponds to the depth marking  67  equal to the length of the screw to be used. The calibration of the depth markings  67  correspond to the distance from the chuck end  62  of the sleeve  60  to the stand off ring  80  in the default position at each position of the edge between the front section  26  and the threaded section  28 . Of course, two or more sets of depth markings  67  may be provided. For example, where two depth markings  67  are provided, one may indicate metric units and the other may indicate English units. In an alternate embodiment, the sleeve  60  can include two slots  66  each with different depth markings. 
   To permit a fastener to have a stand off from the material in which it is engaged with, a stand off ring  80  is provided. The stand off ring  80  is hollow with internal threads that correspond to the external threads  29  of the cylindrical member  20 . The stand off ring  80  is located between the sleeve  60  and the shank  30 , specifically the stand off ring  80  may contact the stop washer  36  between the threaded section  28  and the shank  30 . In the preferred embodiment, shown in  FIG. 1 , the stand off ring  80  can be rotatably translated to a position at the extreme end of the threaded section  28  (closest to the shank  30 ) where the height adjustment ring contacts the stop washer  36  on the cylindrical member  20 . The stand off ring  80  is in the default position when it abuts the stop washer  36 . The stand off ring  80  may be rotated such that it translates away from the stop washer  36  and towards the sleeve  60  along the longitudinal axis of the cylindrical member  20 . 
   In operation, the screw guide  10  is preferably set for use with a screw in the following manner. Initially, the screw guide  10  is set to the length of the screw that will be driven by the screw guide  10 . To set the length, the stop ring  40  is rotated by the user, which will translate the stop ring  40  along the length of the cylindrical member  20 . While operating the stop ring  40 , the user holds the sleeve  60  so that the ledge  69  of the chuck end  62  abuts against the stop ring  40 . The sleeve  60  is aligned over the stop ring  40 , so that the stop ring aperture  68  is positioned over the stop ring  40  to allow the user to rotate the stop ring  40 . As the sleeve  60  translates along the cylindrical member  20 , the user views the slot  66  and adjusts the stop ring  40  to position the edge between the front section  26  and the threaded section  28  to the position corresponding to the depth marking  67  of the screw height to be used. The length of the slot  66  and the position of the depth markings  67  along the slot  66  can be dimensioned according to the range of screw lengths that are intended to be used with the screw guide  10 . When the height adjusting ring  80  is in its default position, i.e. backed out as far as possible towards the end of the threaded section  28  closest to the second end  22  of the cylindrical member, the distance between the chuck end  62  of the sleeve  60  and the stand off ring  80  corresponds to the position of the edge between the front section  26  and the threaded section  28 , as calibrated by the depth markings  67 . 
   The stand off height of the screw head above the surface of the material into which the screw is inserted can also be set using the screw guide  10 . As was discussed above, the stand off ring  80  is normally positioned with respect to the cylindrical member  20  such that the stand off ring  80  is located at the default position at the end of the threaded section  28  closest to the second end  22  of the cylindrical member  20 . If the user desires to set a screw stand off height the user pulls the sleeve  60  towards the stand off ring  80  to force the sleeve  60  to contact the stand off ring  80 . The user then rotates the stand off ring  80  about the cylindrical member  20  a sufficient number of turns to move the stand off ring  80  such that the sleeve moves toward the first end  21  of the cylindrical member  20  until the edge between the front section  26  and the threaded section  28  corresponds to the desired stand off height as read by the depth markings next to the slot  66 . The stand off height will be repeatable as long as the user maintains the stand off ring  80  at a constant position with respect to the cylindrical member when inserting the screws into the material, and the user continues to use screws with the same length. 
   In operation, the screw guide  10  is operated as follows. After the device  10  is adjusted for the appropriate screw length and a desired screw head stand off height is set, if any, the user inserts shank  30  into the chuck of a drill or any other tool that has sufficient torque to rotate the screw guide  10  in the presence of sufficient downward force to insert a screw into the material. 
   After the shank  30  is rotatably engaged in the chuck of the drill, a screw is presented to the removable tip  24  such that the extending structure for the removable tip  24  engages the screw head. When the screw is engaged with the removable tip  24 , the user sets the screw in the desired position and then applies torque to the shank  30  of the cylindrical member  20 , which rotates the cylindrical member  20  along with the rotation of the chuck. When the screw is being inserted, the user holds the sleeve  60  so that the tip end  61  of the sleeve  60  is flush with the work surface. Additionally, as the screw is being inserted, the cylindrical section  20  moves closer to the work surface, therefore the stand off ring  80  moves closer to the chuck end  62  of the sleeve  60 . Eventually, the stand off ring  80  contacts the sleeve  60 , which prohibits the depth guide  10  from driving the screw further into the work surface. 
   The screw guide  10  may be used again to drive another screw into the material. Assuming the user desires to drive the same size screw with the same set off height, the user simply removes the screw guide  10  from the work surface and allows the sleeve  60  to move towards the first end  21  of the cylindrical member until the ledge  69  of the sleeve  60  makes contact with the stop ring  40 . The user may drive another screw into a work surface using the procedure described above. Alternatively, if the user wishes to use a different sized screw or achieve a different stand off height, the user should adjust the screw guide  10  for the desired screw size or stand off height as described above, then insert the screw into the work surface. 
   While the preferred embodiments of the invention have been described, it should be understood that the invention is not so limited and modifications may be made without departing from the scope of the invention. The scope of the invention is defined by the appended claims, and all devices that come within the meaning of the claims, either literally or by equivalence, are intended to be embraced therein.