Patent Publication Number: US-6704984-B2

Title: Prewinder apparatus for installation tools

Description:
FIELD OF THE INVENTION 
     The present invention relates to prewinding tools for installing helical coil inserts into tapped holes, and more particularly to a prewinding apparatus selectively attachable to an installation tool. 
     BACKGROUND OF THE INVENTION 
     Helical coil inserts are commonly installed into tapped holes of a work piece so that threaded fasteners, such as screws, can be held more securely. These inserts provide a female thread of a harder material than the material of the original threaded hole, into which they are installed. In other words, the inserts improve the gripping of threaded fasteners made of relatively hard materials, such as various steel alloys, when installed in relatively soft parent materials, such as aluminum. Helical coil inserts typically include a tang used as a grip by a mandrel of the installation tool for screwing the helical coil insert into the tapped hole. 
     Helical coil inserts of this kind are usually installed by pre-winding then to reduce their diameter, and then rotatably threading them into a tapped hole. Once installed, the inserts expand from their contracted diameters and press radially outward against the walls defining the tapped holes, whereby the insert is securely held in place. Various tool are provided for performing this function, however, these typically are limited to larger single-function tools such as those driven by an air or electric motor. Such tools further include a tubular body having a threaded bore extending along its axis and an opening at one end of the body for placing the insert in the bore. A mandrel is rotated by the motor within the threaded bore and into engagement with the insert. Advancement of the mandrel forces the insert through a prewinder, which contracts the insert prior to advancement into a tapped hole in an adjacent work piece. Once the insert is installed at the correct depth in the bore of the work piece, the mandrel is reversed until it is removed from the insert. Upon removal of the mandrel, the insert expands radially to engage the wall of the tapped hole. 
     As mentioned above, such installation tools are generally dedicated tools performing the functions of prewinding and installing inserts. In order to perform these functions a special prewinder tool must be purchased. In all manufacturing environments, there is a continuous drive to reduce costs. Having to purchase special tools to perform specific functions significantly increases costs. Therefore, it is desirable in the industry to provide a prewinder apparatus that is adaptable for operation with an existing tool. In this manner, the number of tools may be reduced and ease of use may be improved, thereby significantly reducing overall costs. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention provides a prewinder apparatus selectively attachable to a drive tool for prewinding a helical coil insert. The prewinder apparatus includes a support structure selectively attachable to the drive tool and a prewinder attached to an end of the support structure. The prewinder includes first and second threaded apertures and a mandrel preferably having a threaded end and a coupling end. The threaded end engages the first threaded aperture and selectively engages the second threaded aperture. The coupling end is in selective operable engagement with the drive tool, whereby the drive tool rotatably drives the mandrel relative to the prewinder. Specifically, the mandrel rotatably drives the helical coil insert through the second threaded aperture to prewind the helical coil insert. 
     In a first preferred embodiment, the prewinder apparatus is a reciprocating mandrel prewinder apparatus. This reciprocating-mandrel prewinder apparatus includes a drive sleeve having a main body with a coupling stem in selective engagement with the drive tool and a cavity for slidably receiving the coupling end of the mandrel therein. The coupling end includes a radially extending pin slidably disposed within a slot running along a length of the drive sleeve. The drive sleeve is rotatably driven by the drive tool for reciprocally driving the mandrel within the prewinder apparatus. The reciprocating mandrel prewinder apparatus preferably includes a pair of adjustable stops operably engageable with the drive sleeve to define a range of sliding motion of the mandrel relative thereto. 
     In a second preferred embodiment, the prewinder apparatus is a stationary mandrel prewinder apparatus. The mandrel of the stationary-mandrel prewinder apparatus is rotatably driven by the drive tool, thereby reciprocally driving the support structure of the stationary-mandrel prewinder apparatus relative to the drive tool. For facilitating movement of the support structure, the support structure includes a slot for slidably engaging the drive tool. The stationary-mandrel prewinder apparatus preferably includes an adjustable stop, which is adjustable along a length of the mandrel to define a range of sliding motion of the support structure relative to the drive tool. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
     FIG. 1A is a side cross-sectional view of a reciprocating-mandrel prewinder apparatus in accordance with the principles of the present invention; 
     FIG. 1B is a perspective view of the reciprocating-mandrel prewinder apparatus of FIG. 1A; 
     FIG. 2A is a side, partial cross-sectional view of an alternative embodiment of the reciprocating-mandrel prewinder apparatus of FIGS. 1A and 1B; 
     FIG. 2B is a perspective view of the alternative embodiment of the reciprocating-mandrel prewinder apparatus of FIG. 2A; 
     FIG. 3 is a side view of a stationary-mandrel prewinder apparatus in accordance with the principles of the present invention; 
     FIG. 4 is a detailed cross-sectional view of a prewinder of the reciprocating-mandrel prewinder apparatus shown in either of FIGS. 1 and 2; 
     FIG. 5 is a side view of the reciprocating-mandrel prewinder apparatus of FIG. 1 during a prewinding operation; 
     FIG. 6 is a side view of the stationary-mandrel prewinder apparatus of FIG. 3 during a prewinding operation; and 
     FIG. 7 is a cross-sectional view of an alternative mandrel for use with a tangless helical coil insert. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
     With reference to FIGS. 1A-3 the present invention provides first and second preferred embodiments of a prewinder apparatus  10 , 200  respectively, selectively attachable to a drive tool  12 . The prewinder apparatus  10 , 200  is provided as an installation tool for installing helical wire inserts into a threaded opening. The drive tool  12  is preferably an electric tool, such as an electric screwdriver, a variable speed drill and the like. Further, it is anticipated that the drive tool  12  may be either a corded or cordless (i.e. battery powered) tool. 
     With particular reference to FIGS. 1A and 1B, the present invention provides a reciprocating mandrel prewinder apparatus  10 , including a support structure  14 , a prewinder  16 , a mandrel  18 , a drive sleeve  20  and a pair of adjustable stops  22 ,  24 . The prewinder  16  is disposed in an end of the support structure  14  and the mandrel  18  is rotatably disposed therethrough. The mandrel  18  is operatively interconnected to the drive sleeve  20  and axially moveable therein. The adjustable stops  22 ,  24  are disposed about the drive sleeve  20  and are adjustable relative thereto for limiting the axial movement of the mandrel  18  relative to the drive sleeve  20 . The support structure  14  is selectively interconnected to an end of the drive tool  12 , whereby the drive sleeve  20  is interconnected with a drive unit  26  of the drive tool  12  for driving the mandrel  18 . 
     In a first embodiment, the support structure  14  is generally frusto-conical in shape having a frusto-conical cavity  28 . A slot  30  is provided through a wall  32  of the support structure  14  for accessing components disposed therein. A distal end of the support structure  14  includes a cylindrical cavity  34  having an aperture  36  extending to the frusto-conical cavity  28 . A threaded aperture  38  is also provided and radially extends from the cylindrical cavity  34  through the support structure  14  for receiving a setscrew  40  therein. An open end of the support structure  14  includes a circumferential groove  42  for engaging a circumferential mating lip  44  disposed about the drive tool  12 . In this manner, the support structure  14 , and thus the prewinder apparatus  10 , may be easily interconnected with the drive tool  12 . 
     With particular reference to FIG. 4, the prewinder  16  includes a foot  46 , a semi-cylindrical intermediate body  48  and a leading end  50 . The foot  46  is received into the cylindrical cavity  34  of the support structure  14  and includes a first threaded aperture  52  therethrough. The semi-cylindrical intermediate body  48  connects the foot  46  and leading end  50 , and provides a slot  54  (see FIG. 1A) providing access to a semi-circular recess  56 , whereby a user can load a helical coil insert  58  (see FIG. 5) into the prewinder  16 . The leading end  50  includes an aperture  59 , which is a reduced diameter aperture for providing a prewinding aperture, as explained in further detail hereinbelow. The prewinder  16  is mounted to the support structure  14  by inserting the foot  46  into the cylindrical cavity  34 . The prewinder  16  is held in place by the setscrew  40 . 
     Again referencing FIGS. 1A and 1B, the mandrel  18  is generally cylindrical along its length and includes a threaded leading end  60  and an opposing end  62  having a pin  64  extending radially therefrom. The threaded leading end  60  includes a contour  66  for engaging the helical coil insert  58  and is slidably disposed through the aperture  36  of the support structure  14 . Further, the mandrel  18  is in threaded engagement with the first threaded aperture  52  of the prewinder  16 . As the mandrel  18  is caused to rotate, as described in further detail hereinbelow, it is drawn axially through the first threaded aperture  52 , as a result of the threaded engagement therebetween. 
     The drive sleeve  20  includes a generally cylindrical housing  68  having a cavity  70  disposed axially therein and a slot  72  running along the length of the housing  68 . A generally hexagonal stem  74  axially extends from an end of the drive sleeve  20 . It will be appreciated that, although the stem  74  is provided herein as generally hexagonal, other geometries may be readily substituted therefor. The hexagonal stem  74  is receivable into the drive unit  26  of the drive tool  12  to enable the drive tool  12  to rotatably drive the drive sleeve  20 . The mandrel  18  is axially received into the cavity  70  of the drive sleeve  20 , whereby the radially extending pin  64  extends into the slot  72  of the mandrel  18 . In this manner, the drive sleeve  20  and mandrel  18  are fixed for concurrent rotation while the mandrel is axially slidable within the cavity  70  of the drive sleeve  20 . 
     Each adjustable stop  22 ,  24  is disposed about an outside circumferential surface  76  of the drive sleeve  20  include a ring-shaped body  78  having an aperture  80  therethrough and a guide  82  extending radially inward. The drive sleeve  20  extends through the aperture  80 , whereby the guide  82  is slidably received into the slot  72  of the drive sleeve  20 . Each adjustable stop  22 ,  24  is slidable along the drive sleeve  20  until a desired position is achieved. Further, each adjustable stop  22 ,  24  includes a setscrew  84  disposed through a threaded aperture  86  of the ring-shaped body  78 . The setscrews  84  are operable to lock the adjustable stops  22 ,  24  relative to the drive sleeve  20 . As the mandrel  18  slides axially within the drive sleeve  20 , the radially extending pin  64  ultimately contacts one of the adjustable stops  22 ,  24 , prohibiting further sliding of the pin  64  within the slot  72 . In this manner, the length of sliding motion of the mandrel  18  within the drive sleeve  20  may be selectively defined via adjustment of the adjustable stops  22 ,  24 . As a result, the depth that the helical coil insert  58  is installed is controlled and may be varied as particular design requirements dictate. 
     With reference to FIGS. 2A and 2B, an alternative support structure is provided as a bracket assembly  14 ′. The bracket assembly  14 ′ includes brackets  88 , each including a straight portion  90 , an angular step portion  92  and an end portion  94 . The foot  46  of the prewinder  16  is received in the end portions  94  of the bracket  88  and is retained in position by a pair of screws  96  that are received through apertures  98  of the end portion  94  and are in threaded engagement with a pair of threaded apertures  100  of the foot  46  of the prewinder  16 . A distal end of the portion  90  of each bracket  88  includes an aperture  102  for receiving a bolt  104  therethrough to retain the prewinder apparatus  10  on the drive tool  12 . 
     With reference to FIG. 5, operation of the prewinder apparatus  10  will be described in detail. The helical coil insert  58  is placed within the semi-circular recess  56  of the semi-cylindrical intermediate body  48  through the slot  54 , and is aligned with the prewinder aperture  59  of the leading end  50  of the prewinder  16 . To accommodate loading of the helical coil insert  58  into the prewinder, initially, the mandrel  18  is partially retracted into the first threaded aperture  52  of the foot  46 . Subsequent actuation of the drive tool  12  causes the drive unit  26  to rotatably drive the drive sleeve  20 , thereby rotatably driving the mandrel  18 . As the mandrel  18  rotates, the threaded engagement with the first threaded aperture  52  of the foot  46  causes the mandrel  18  to move axially, eventually engaging the helical coil insert  58 . Upon engagement, the threaded leading end  60  of the mandrel  18  slides through the helical coil insert  58  until the contour  66  grabs a tang  106  of the helical coil insert  58 . The mandrel  18  rotates the helical coil insert  58  into the prewinder aperture  59  of the leading end  50 , thereby prewinding the helical coil insert  58  about leading end  60  of the mandrel  18 . Continued advancement of the mandrel  18  causes the pre-wound, helical coil insert  58  to axially move from the prewinder aperture  59  into a threaded bore  108  of a work piece  110 . Upon complete insertion of the helical coil insert  58  within the threaded bore  108 , the driving action of the drive tool  12  is reversed to disengage the contour  66  from tang  106  and withdraw the mandrel  18  from the insert  58  and bore  108 . 
     With particular reference to FIG. 3, the present invention also provides a stationary mandrel prewinder apparatus  200 , including a bracket assembly  212 , a prewinder  214 , and a mandrel  216 . The prewinder  214  is held between the brackets  217  of the bracket assembly  212  and the mandrel  216  is rotatably disposed therethrough. The mandrel  216  is operatively interconnected to the drive tool  12 . An adjustable stop  218  is provided and is disposed about the mandrel  216 . The adjustable stop  218  is adjustable relative to the mandrel  216  for limiting movement of the prewinder apparatus  200  relative to the drive tool  12 . 
     The prewinder  214  is similar to the prewinder  16  described hereinabove and includes a foot  220 , a semi-cylindrical intermediate body  222  and a leading end  224 . The foot  220  is adapted for reception between the brackets  217  of the bracket assembly  212  and includes a first threaded aperture  226  therethrough. The semi-cylindrical intermediate body  222  interconnects the foot  220  and leading end  224 , and provides a slot  228  for accessing an arcuate recess  230  for loading a helical coil insert  232  (see FIG. 6) into the prewinder  214 . The leading end  224  includes an aperture  234 , which is of a reduced diameter for providing a prewinding aperture  234 , as explained in further detail hereinbelow. The prewinder  214  is mounted to the bracket assembly  212 , whereby the foot  220  is secured by a pair of screws  236 . 
     The mandrel  216  is generally cylindrical along its length and includes a threaded leading end  238  and an opposing stem end  240 . The stem end  240  is generally hexagonal, although, it will be appreciated that other geometries may be readily substituted therefor. The hexagonal stem  240  is received into the drive unit  26  of the drive tool  12 , as described for the prewinder apparatus  10  above, to enable the drive tool  12  to rotatably drive the mandrel  216 . The threaded leading end  238  includes a contour  242  for engaging the helical coil insert  232 . Further, the mandrel  216  is in threaded engagement with the first threaded aperture  226  of the prewinder  214 . As the mandrel  216  is caused to rotate, as described in further detail hereinbelow, the prewinder  214  is drawn axially about the mandrel  216  as a result of the threaded engagement therebetween. In this manner, the mandrel  216  remains stationary relative to the drive tool  12  and the prewinder  214  moves axially relative thereto. 
     The bracket assembly  212  is similar to the bracket assembly  14 ′ described hereinabove and includes the brackets  217 . Each bracket  217  includes a straight portion  244 , an angular step portion  246  and an end portion  248 . The foot  220  of the prewinder  214  is received between the end portions  248  of the brackets  217  and is retained in position by the screws  236  that are received through apertures  250  of the end portions  248  and are in threaded engagement with a pair of threaded apertures  252  of the foot  220  of the prewinder  214 . A distal end of the straight portion  244  of each bracket  217  includes a slot  254  for receiving bolts  256  therethrough to slidably retain the prewinder apparatus  200  on the drive tool  12 . The slots  254 , enable the bracket assembly  212  to slide axially relative to the drive tool  12 . 
     The adjustable stop  218  includes a cylindrical body  260  having a cylindrical cavity  262  disposed therethrough and a radial threaded aperture  264  for receiving a setscrew  266  therein. The mandrel  216  is slidably received through the cylindrical cavity  262  and the adjustable stop  218  is locked in position along a length of the mandrel  216  by engagement of the setscrew  266  with a circumferential surface  268  of the mandrel  216 . The adjustable stop  218  defines an axial length along which the prewinder  214  is able to travel relative to the mandrel  216 . As a result, the depth that the helical coil insert  232  is installed is controlled and may be varied as particular design requirements dictate. 
     With particular reference to FIG. 6, operation of the prewinder apparatus  200  will be described in detail. The helical coil insert  232  is placed within the semi-circular recess  230  of the semi-cylindrical intermediary  222  through the slot  228  and is aligned with the prewinder aperture  234  of the leading end  224  of the prewinder  214 . To accommodate loading of the helical coil insert  232  into the prewinder  214 , initially, the prewinder  214  and attached bracket assembly  212  are forwardly advanced along the threaded leading end  238  of the mandrel  216 . Subsequent actuation of the drive tool  12  causes the drive unit  26  to rotatably drive the mandrel  216 . As the mandrel  216  rotates, the threaded engagement with the first threaded aperture  226  of the foot  220  causes the prewinder  214  and attached bracket assembly  212  to be drawn toward the drive tool  12 , thereby enabling the mandrel  216  to engage the helical coil insert  232 . As the prewinder  214  and attached bracket assembly  212  rearwardly advance, the bracket assembly  212  slides axially relative to the drive tool  12  via the slots  254 . Upon engagement, the threaded leading end  238  of the mandrel  216  axially moves through the helical coil insert  232  until the contour  242  grabs a tang  270  of the helical coil insert  232 . The mandrel  216  rotates the helical coil insert  232  into the prewinder aperture  234  of the leading end  224 , thereby contracting the helical coil insert  232  about the threaded leading end  238  of the mandrel  216 . Continued advancement of the prewinder  214  and attached bracket assembly  212  causes the mandrel  216  to rotate the pre-wound, helical coil insert  232  from the prewinder aperture  234  into a threaded bore  272  of a work piece  274 . Upon complete insertion of the helical coil insert  232  within the threaded bore  272 , the driving action of the drive tool  12  is reversed to disengage the contour  66  from tang  106  and advance the prewinder  214  and attached bracket assembly  212  forward, relative to the drive tool  12 , thereby withdrawing the mandrel  216  from the helical coil insert  232  and the threaded bore  272 . 
     The above-described mandrels are generally provided for prewinding helical coil inserts having a tang. With reference to FIG. 7, an alternative mandrel  280  is provided for prewinding tang-less helical coil inserts. It will be appreciated that the mandrel  280  may be implemented in either prewinder apparatus  10 , 200 . The mandrel  280  includes a cylindrical body  282  having a stepped end  284  of a reduced diameter and a coupling end  286  for selective interconnection with either the drive sleeve  20  or the drive unit  26 . 
     A first threaded portion  288  is provided about a circumferential surface  290  of the cylindrical body  282  and a second threaded portion  292  is provided about a circumferential surface  294  of the stepped end  284 . A cavity  296  is disposed through a length of the cylindrical body  282  and a lever arm  298  is pivotally supported therein. The lever arm  298  includes an engagement end  300 , a biasing end  302  and a fulcrum  303  disposed therebetween. A spring  304  is disposed within a cavity  306  of the cylindrical body  282  and engages the biasing end  302  of the lever arm  298  for biasing the lever arm  298  in a first position. When in the first position, a tab  308  of the engagement end  300  extends through an aperture  310  of the stepped end  284 . 
     The first threaded portion  288  of the mandrel  280  is in threaded engagement with the first threaded aperture  52 , 226  of the prewinder  16 , 214  and the second threaded portion  292  is in selective engagement with a tang-less helical coil insert  312  for driving the helical coil insert  312  through the prewinder aperture  59 , 234 . The tang-less helical coil insert  312  includes a recess  314  formed in an internal circumferential surface  316 . It should be noted that the recess  314  can be formed at either end for providing a bi-directional helical coil insert  312 . As the mandrel  280  is driven into contact with the helical coil insert  312 , the stepped end  284  threadedly engages the internal circumferential surface  316  thereof. Initially, the tab  308  of the engagement end  300  is pressed downward into the cavity  296 , thereby causing the lever  298  to pivot against the bias of the spring  304 . As the stepped end  284  of the mandrel  280  is driven deeper within the helical coil insert  312 , the spring  304  biases the tab  308  outward against the internal circumferential surface  316  until the tab  308  ultimately slides into engagement with the recess  314 . Once engaged with the recess  314 , the mandrel  280  rotatably drives the helical coil insert  312  through the prewinder aperture  59 , 234  and into the work piece  110 , 274 . 
     The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.