Key assembly tool
This invention has as its purpose to provide an improved tool for assembling slotted plastic heads with the metal shanks of keys. 
     For quite some time, keys for tumbler locks have been color coded to identify them with the locks they open. The most convenient way of doing this is by providing different colored plastic heads that can be detachably secured to the shanks of the keys. For this purpose, the plastic heads are slotted and the shanks of the keys have their head end portions shaped and dimensioned to snugly fit the slot in the plastic heads. In fact, the outer end portion of the key shank, which is apertured as is customary, usually has small though well defined inwardly facing shoulders to snap over the edges of the slot in the plastic head and prevent accidental or unintentional separation of the head from the key. 
     In assembling the head and key, the latter is forced into the slot in the head. Obviously, this impaling operation is best performed with a tool specifically designed for the purpose, but the tools heretofore available left much to be desired. There has been a real need for a practical and efficient tool with which a selected plastic slotted key head can be quickly and easily attached to the shank of a key or detached therefrom. This invention supplies that need. 
     As will be more fully described hereinafter, the invention resides in a tool that has a body having a head-supporting surface with an abutment rising therefrom to receive and support a head, with its slot parallel to said supporting surface and perpendicular to said abutment; a carriage slidably mounted on the body; means constraining the carriage to linear advance towards and retraction from said abutment; key shank engaging means on said carriage to so engage the shank of a key that, upon advance of the carriage towards said abutment, the head end portion of the key shank is forced to move endwise in one direction through the slot of a head in position on the body in front of said abutment; and manually operable motion-producing means reacting between the body and the carriage for advancing and retracting the carriage. 
     With these observations and objectives in mind, the manner in which the invention achieves its purpose will be appreciated from the following description and the accompanying drawings, which exemplify the invention, it being understood that changes may be made in the specific apparatus disclosed herein without departing from the essentials of the invention set forth in the appended claims. 
     The accompanying drawings illustrate one complete example of the embodiment of the invention constructed according to the best mode so far devised for the practical application of the principles thereof, and in which: 
     FIG. 1 is a perspective view of a key of the type with which this invention is concerned; 
     FIG. 2 is a perspective view of the component parts of the key -- that is, its shank and head, disassembled; 
     FIG. 3 is a perspective view of the tool of this invention, illustrating the structure thereof by which the shank of the key and its head are assembled; 
     FIG. 4 is a perspective view of the opposite side of the tool at which its parts coact to detach the shank of the key from the head; 
     FIG. 5 is an exploded perspective view of the component parts of the tool; and 
     FIG. 6 is a cross sectional view through FIG. 3 on the plane of the line 6--6. 
    
    
     Referring to the drawings and, for purposes of nomenclature, note that the key shown assembled in FIG. 1 and disassembled in FIG. 2, comprises a shank S having a bitted blade B and a slotted plastic head H into which the outer end portion of the shank is inserted. As is customary, at the base of the blade there are well defined shoulders 4 and, beyond these, shoulders 5 which limit insertion of the shank into the slot through the head. Similar shoulders 6 on the outer end portions of the shank snap over the adjacent edges of the slot during assembly of the key to prevent accidental or unintentional disassembly. 
     With reference to the tool, the numeral 7 designates its body, which -- as best seen in FIG. 5 -- has a main section 8 on which the mechanism of the tool is located, and a handle 9 projecting therefrom. The main body section has opposite flat, substantially rectangular parallel surfaces 10--10&#39; with abutments 11--11&#39; rising therefrom. 
     Slidably mounted on the main section 8 of the body is a carriage 12 which is constrained to linear motion towards and from the abutments 11--11&#39; by a pair of parallel guide rails 13 extending along the side edges of each of the opposite flat sides of the body. The carriage comprises a pair of flat-sided bar-like members 14--14&#39; connected with one another by a pair of rivets 15 that pass through spacers 16 by which the bar-like members are held spaced apart a distance slightly greater than the thickness of the main section of the body so that the bar-like members slide freely over the surfaces 10--10&#39;. 
     An elongated hole 17 through the main section of the body accommodates the spacers 16, and by virtue of the width of the bar-like members being just slightly less than the distance between the guide rails 13 and their thickness being substantially equal to the height of the guide rails, the outer surfaces of the guide rails and the bar-like members at each side of the body form substantially continuous coplanar surfaces. 
     At the side of the tool at which the surface 10 is located, the carriage and the abutment 11 coact to force the shank S of a key into the slot of a selected plastic head H upon advance of the carriage towards the abutment. For that purpose, the side of the abutment facing the carriage is concavely arcuate to fit the convexly curved outer edge of any selected key head, it being understood that except for color, all heads are alike. 
     The selected head is laid on the surface 10 with its outer edge against the concavely curved side of the abutment, and the shank of a key to be fitted with the selected head is laid onto the bar-like member 14 that constitutes the adjacent portion of the carriage, between a pair of sharply defined ridges or fences 18 that project upwardly from the side edge portions of the member 14. By these ridges or fences, the shank of the key is held against lateral displacement from the carriage and, by the engagement of the shoulders 4 at the base of the shank with the ends 18&#39; of the ridges or fences, the shank is constrained to move with the carriage as it is advanced towards the abutment. 
     Attention is directed to the fact that by virtue of the thickness of the bar-like member 14, the surface thereof on which the shank of the key is laid -- and hence the underside of the projecting head end portion of the shank 13  is spaced from the surface 10 an amount to achieve alignment of the shank with the mouth of the slot in the head. Accordingly, as the carriage is advanced, the rounded outer end of the key shank is driven into the slotted head. The shoulders 5 on the side edges of the key shank limit its insertion into the head, and -- at that point -- the small shoulders 6 snap over the edges of the slot in the head and the rounded end of the shank protrudes beyond the outer edge of the head just far enough to expose the hole in the shank. To accommodate this projection of the shank beyond the outer edge of the head, the concavely curved side of the abutment has a central depression 19. 
     The manner in which the carriage is advanced will be described after the immediately following description of the structure of the tool by which the shank of a key can be detached from its head. This is done at the side of the tool at which the surface 10&#39; is located, as illustrated in FIG. 5. 
     However, before proceeding it should be noted that the flat surfaces 10 and 10&#39; are properly identifiable as head-supporting surfaces, inasmuch as, in each case, the head of the key -- whether it is to be attached or detached -- is laid thereon preparatory to the operation to be performed. 
     With particular reference to FIG. 5, note that the abutment 11&#39; is medially interrupted to provide a passage 20 extending from the concavely curved inner side of the abutment to its opposite outer side, and that the bar-like member 14&#39; has a finger 21 projecting from its front end. This finger has a cross sectional side and shape to permit its entry into the slot in the key heads, and is offset from the plane of the member 14&#39; by an amount approximately half the thickness of the plastic heads. Accordingly, the finger will be coplanar with the shank of a key laid on the surface 10&#39; with its blade projecting through the passage 20 and the inner edge of its head bearing against the abutment 11&#39;. 
     With the key in position on the tool, advance of the carriage will bring the outer end of the finger 21 into engagement with the rounded end of the shank that protrudes from the head, and by continued advance of the carriage, the shank of the key will be dislodged from the head, since the size and shape of the finger permits it to enter the slot in the head. 
     Reciprocatory movement of the carriage is effected by motion-producing means reacting between the body and the carriage. That motion producing means comprises a long and short armed bell crank lever 22 pivotally connected as at 23 to a laterally projecting portion 24 of the main section 8 of the body. The short arm 25 of this lever has a motion-imparting connection 26 with the carriage and its long arm 27 overlies the handle 9 that projects from the main section of the body. In effect, the long arm of the bell crank lever and the handle form a pair of pincers which, upon being grasped and squeezed together, impart advancing motion to the carriage -- and, obviously, movement of the long arm of the bell crank lever away from the handle, retracts the carriage. 
     Attention is directed to the novel construction of the bell crank lever 22. It is a sheet metal stamping with parallel flat side walls 28 joined by an outer center wall 29. The side walls 28 are shaped to provide a pair of parallel flat flanges 30 which embrace the assembled body and carriage and form the short arm 25 of the lever. Outwardly of the flanges 30 the side walls 28 have their inner edge portions 31 turned in towards one another and brought into edge-to-edge contact, to thus impart a neat cross sectional shape to the long arm of the lever. 
     The motion imparting connection 26 between the short arm of the bell crank lever and the carriage is formed by a rivet 32 which connects the flanges 30 and passes through aligned transversely extending slots 33 in the bar-like members 14--14&#39; and through the elongated hole 17 in the main section 8 of the body, which hole is widened at its inner end to accommodate the arcuate travel of the rivet 32 as the bell crank lever is rocked to retract the carriage. Collision of the rivet with an edge of the hole 17 defines the fully retracted position of the carriage; and the limit of its advance is defined by collision of the inturned edge portions 31 at the underside of the long arm of the lever with the adjacent edge of the body. 
     Those skilled in the art will appreciate that the invention can be embodied in forms other than as herein disclosed for purposes of illustration.