Abstract:
An apparatus for removing helical thread inserts having a removal notch formed along the female thread surface. The apparatus can selectively extract helical thread inserts by selectively engaging the removal notch and actuating the end of the insert radially inward to prevent the end of the insert from engaging threads of the bore which it is disposed in. The apparatus includes a handle, a head attached to the handle and a manually operable key. The head includes a hole formed in an offset location. A key having an engaging lip on the end is disposed in the hole and acting along a eccentric pattern to selectively engage the removal notch of the insert and allow for easier removal of the insert.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a tool for removing thread inserts. More specifically, the present invention relates to a hand tool having an offset key located therein to selectively engage a removal notch on a helical thread insert for removing the helical thread insert from a threaded bore within a parent material.  
         BACKGROUND OF THE INVENTION  
         [0002]    Helical thread inserts are used in many industries to provide female threads in a threaded bore located in a parent material having a relatively low hardness. The helical thread inserts are installed using a special tool that grasps a removable tang located at the leading end of the helical thread insert and guides the insert into the threaded bore in the parent material. The tang is then removed to provide a threaded bore having female threads with a greater hardness than the female threads formed in the original threaded bore. In the event that the helical thread inserts become worn or damaged, removal of the thread insert may be required.  
           [0003]    In recognition of the need to remove helical thread inserts several devices have been developed. Some helical thread inserts include a pair of diametrically opposed notches formed in the last thread of the insert. The notches a allow a flathead screwdriver or other tool to apply a counterclockwise torque to guide the insert out of the original threaded bore. However, the use of a flathead screwdriver or other tool may apply forces that drive the insert back into the threaded bore or expand the last thread of the insert radially outward. If the tool applies a force on the insert that pushes the insert back into the original threaded bore, removal of the thread insert is made more difficult because the desired direction of movement of the insert, out of the hole, is opposite of the force that is applied on the insert. Additionally, if the tool causes expansion of the last thread of the insert, the end of the thread may dig into the parent material causing removal of the thread insert to be more difficult and possibly damaging the parent material. In recognition, thread inserts have been developed that have chamfered and radiused edges formed around the end of the last thread to prevent the thread from digging into the parent material.  
           [0004]    However, one concern associated with helical thread inserts is retention capability, the ability of the insert to remain in the threaded bore. The use of chamfered or radiused ends reduces the ability of the end of the thread insert to grasp the parent material to prevent counterclockwise movement, leading to inadvertent removal of the insert. Additionally, the increasing popularity of stainless steel helical thread inserts in combination with stainless steel threaded fasteners may lead to galling. If galling occurs, the forces applied to the threaded fastener are directly transferred to the helical thread insert, thus increasing the likelihood that the helical thread insert will not remain in the threaded bore.  
         SUMMARY OF THE INVENTION  
         [0005]    Accordingly, the present invention provides an apparatus for removing helical thread inserts having a removal notch formed in the last thread. The apparatus selectively engages the removal notch on the helical thread insert and actuates the end of the thread insert radially inward away from the parent material, thereby eliminating the contact between the end of the thread insert and the parent material.  
           [0006]    The apparatus is generally comprised of a sleeve, a head and a key. The head includes an offset bore disposed therethrough. The key, which is manually actuable between an engaging position and a neutral position is located within the bore of the head and contains an engaging face that selectively engages the removal notch of the helical thread insert in order to actuate the end portion of the insert radially inward.  
           [0007]    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  
       [0008]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0009]    [0009]FIG. 1A is an top view of a helical thread insert having a removal tool engaged thereto;  
         [0010]    [0010]FIG. 1B is a side view of the helical thread insert and removal tool of FIG. 1A;  
         [0011]    [0011]FIG. 2 is an end view of a helical thread insert;  
         [0012]    [0012]FIG. 3 is a exploded view of a helical thread removal tool according to the preferred embodiment;  
         [0013]    [0013]FIG. 4 is a side view of the head portion of the helical thread removal tool of FIG. 3;  
         [0014]    [0014]FIG. 5 is a side view of the handle portion of the helical thread removal tool of FIG. 3;  
         [0015]    [0015]FIG. 6A is a side view of the key portion of the helical thread removal tool of FIG. 3;  
         [0016]    [0016]FIG. 6B is a detailed view of the end of the key of FIG. 6A;  
         [0017]    [0017]FIG. 7 is a side view of the collar portion of the helical thread removal tool of FIG. 3;  
         [0018]    [0018]FIG. 8 is a perspective view of the helical thread removal tool of FIG. 3 shown in operative engagement with a helical thread insert;  
         [0019]    [0019]FIG. 9A is a section view of the end portion of the thread removal tool of FIG. 1 shown in an initial position along plane A-A;  
         [0020]    [0020]FIG. 9B is an section view of the end portion of the thread removal tool of FIG. 1 shown in an engagement position; and  
         [0021]    [0021]FIG. 9C is an section view of the end portion of the thread removal tool of FIG. 1 shown in a removal position. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0022]    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.  
         [0023]    [0023]FIG. 1A and 1B illustrate a helical thread insert  1  having a prior art extraction tool  5  shown in operative engagement. To extract the helical thread insert  1  from a threaded bore in a parent material, a counterclockwise torque is applied in the direction of arrow A. However, in applying a torque in direction A, a downward force D and radial forces R 1  and R 2  may also be applied. Force D is applied by the operator of extraction tool  5  to engage the end of the extraction tool  5  in the notches  4 A and  4 B of coil  1 . The direction of force D is opposite to the direction that the helical thread insert  1  is desirably traveling, out of the threaded bore. Forces R 1  and R 2  are generated if extraction tool  5  has a tapered engaging side similar to a flathead screwdriver as shown on extraction tool  5  of FIG. 1B. Forces R 1  and R 2  may expand the last thread of the helical thread insert  1  radially outward, engaging the female threads of the softer parent material and making removal more difficult.  
         [0024]    [0024]FIG. 2 illustrates a helical thread insert  6 , for which there is a copending application filed on the same date and owned by the same assignee. Helical thread insert  6  includes a single removal notch  9  located near the end of the last thread of the helical thread insert  6 . With continued reference to helical thread inserts, the helical thread insert  6  shown in FIG. 2 will be used for further reference. However, it is understood that the present invention may be used to remove a helical thread insert similar to the type shown in FIG. 1, FIG. 2 or any type having a removal notch located on the inside surface of the thread that is engageable by the present invention.  
         [0025]    As shown in FIG. 3, a selection view of extraction tool  10  illustrates the parts comprising an extraction tool according to the present invention. Extraction tool  10  is generally composed of a sleeve  14  connected to a head  12  having a key  16  disposed in a non-concentric bore disposed therethrough that is operatively rotated by a collar  18  which is manually actuable by a handle  20 .  
         [0026]    Head  12  of extraction tool  10  is shown in FIG. 4 to include a body portion  26  and a neck  30  interconnected by a bevel portion  28 . Body portion  26  is formed in a cylindrical shape having a circular cross section for operatively receiving sleeve  14 . However, body portion  26  may be constructed in alternative shapes that may be used to receive sleeve  14  or another member similar to sleeve  14 . A threaded hole  40  is formed near the rear of head  12  to selectively secure head  12  to sleeve  14 . Neck  30 , which is connected to body portion  26  through a bevel portion  28  is constructed in a cylindrical shape having a circular cross section that is larger than the minor diameter of helical thread insert  6 . Extending through body portion  26 , bevel portion  28  and neck  30  is a circular bore  38 . Bore  38  is formed offset, not concentric, with body portion  26  or neck  30 . In a preferred embodiment, bore  38  is formed having a diameter that is substantially similar to distance from the centerline of the helical thread insert  6  to removal notch  9  located on the last thread of the helical thread insert  6 . Additionally, bore  38  is preferably constructed so that the centerline of neck  30  is tangent to the outer edge of bore  38 . Extending from the distal end of neck  30  is an undercut portion  36 , through which bore  38  extends, having a diameter that is smaller than the minor diameter of the thread insert. Attached to the end of undercut portion  36  is a pilot journal  32 , having an outer diameter  34  that is substantially similar to the minor diameter of helical thread insert  6 .  
         [0027]    Sleeve  14  is shown in FIG. 5 to be composed of a body portion  62  for manipulating extraction tool  10  and a casing  68  that contains the mechanism of the extraction tool. Body portion  62  is preferably formed in a cylindrical shape having a diameter suitable for grasping by a person. Attached to the end of body portion  62  is casing  68 . Casing  68  is generally defined by a cylinder having a bore  66  disposed therein. Located near the bottom of bore  66  is a slot  72  that extends radially along the casing  68  for a span of 55 degrees for receiving handle  20  which will be discussed in greater detail later. Additionally, a pair of holes threaded holes  74  and  76  are positioned along casing  68  to selectively secure head  12  and retain spring element  21  which is positioned along the outer surface of the casing and biases handle  20  with respect to sleeve  14 .  
         [0028]    Key  16  is shown in FIG. 6A and 6B to be composed of an elongated member having a notch  42  at one end for attaching key  16  to collar  18 , a main body  44  for transferring rotational movement from collar  18  and a cam  46  for engaging removal notch  9  located in the helical thread insert  6 . In a preferred embodiment, notch  42  is formed to have a cross section that is semicircular on shape to allow for engagement by collar  18 . Main body  44  is formed to have a circular cross section that is substantially similar to the size and shape of bore  38 . A detailed view of cam  46  is shown in FIG. 6B. Attached to the distal end of main body  44  is cam  46  which is generally comprised of a flank  48  having a semicircular cross section connected to a concave engaging face  50  that extends upward from shank  48  to form a lip  52 .  
         [0029]    Collar  16  as shown in FIG. 7 is generally composed of a cylindrical body  54  having a bore  56  axially therethrough and a radially extending threaded hole  58 . Bore  56  is similar in size to key  16 , because bore  56  engages the end of key  16 , notch  42 . Threaded hole  58  allows a threaded fastener to secure notch  42  of key  16  with respect to collar  18 . In a preferred embodiment, the threaded fastener that is used to secure collar  18  to notch  42  of key  16  is handle  20 . Handle  20  generally comprises a body portion  78  and a threaded portion  82  (shown in FIG. 3). Threaded portion  82  is inserted into the threaded bore  58  and body portion  78  is disposed within slot  72  as discussed above. Additionally, handle  20  is attached to a spring element  21  as discussed above to provide a biasing force on collar  18  with respect to the sleeve  14 .  
         [0030]    In a preferred embodiment, spring element  21  is a tension spring that provides a biasing force upon handle  20  to operatively urge key  16  into the initial position A shown in FIG. 9A. Spring element  21  is connected to handle  20  and secured to sleeve  14  through the use of a fastener located in threaded bore  58 . The body of spring element  21  is wrapped around the periphery of the sleeve  14  so as to apply the biasing force in a rotational direction.  
         [0031]    With reference to the operation of the extraction tool  10 , it is understood that modifications may be made to the parts that the present invention is comprised of without departing from the scope of the invention. As stated above, the extraction tool  10 , selectively removes helical thread inserts having a removal notch located on the last thread without damaging the parent material that the helical thread insert is disposed in or requiring the use of chamfered or radiused thread ends for removal.  
         [0032]    [0032]FIG. 8 illustrates the configuration required to remove a helical thread insert having a removal notch located on the last thread using the present invention. To remove the helical thread insert  6 , the pilot journal  32  (not shown) is located within the minor diameter of the helical thread insert  6 . To engage the removal notch  9  of helical thread insert  6 , handle  20  must be actuated counterclockwise. When the handle is actuated fully, the handle will rotate through the entire distance of guide slot  72  from point A to point B. When the handle  20  is fully actuated to point B, the collar  18  that is connected to the handle  20  has rotated the engaging lip  52  of cam  46  (not shown) into the removal notch  9  of the helical thread insert  6 . To remove the helical thread insert  6  handle  20  is rotated counterclockwise, along direction C, until the engagement lip  52  of cam  46  has guided the helical thread insert  6  out of the threaded bore.  
         [0033]    With respect to the actuation of key  16  to engage the removal notch  9  of the thread insert, FIGS.  9 A- 9 C depict the operation threrebetween. In FIG. 9A, key  16  is in a neutral position whereby the extraction tool may be rotated to locate the removal notch. The key is positioned such that engagement lip  52  does not extend out side of the minor diameter of the helical thread insert. Key  16  is actuated in this position when the handle  20  is located in position A.  
         [0034]    In FIG. 9B, cam  46  is in an engaged position whereby engagement lip  52  is engaged in the removal notch  9 . Cam  46  is positioned such that engagement lip  52  is protruding into removal notch  9 . Key end  46  is actuated in this position when the handle  20  is located in position B.  
         [0035]    In FIG. 9C the key  16  is in a removal position whereby the engagement lip  52  of the cam  46  is pulling in the end of the helical thread insert  6  along arrow R away from the female threads of the parent material. In this position, the helical thread insert  6  may be removed by actuating sleeve  14  and handle  20  counterclockwise, along direction C concurrently. The force acting on the removal notch pulls the end of the helical thread insert inward and prevents the end of the thread from digging into the parent material.  
         [0036]    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.