referring now the drawings , wherein like numerals indicate like elements , there is illustrated in fig1 a rear view of an apparatus for skin incision which has been identified by the numeral 20 . the skin incision apparatus 20 has a housing 22 having a pair of housing sections 24 and 26 , only one section , the rear section 24 , seen in fig1 . a trigger mechanisms 28 of and for activating the skin incision apparatus 20 projects through an opening 30 , as best seen in fig3 a and 4a , formed between the two section 24 and 26 of the housing 22 . the trigger mechanism 28 is also referred to as a plunger . the rear section 24 of the housing 22 has a hole 32 through which a portion of a spring post 34 projects . the skin incision apparatus 20 has a keeper or safety device 38 which can be removed from a safety position surrounding a portion of the trigger mechanism 28 to prevent inadvertent operation . the keeper 38 is shown removed in fig1 a . the front housing section 26 with the surface configuration not shown and selected components of the skin incision apparatus 20 are shown in hidden line is seen in fig1 a . the skin incision apparatus 20 has , in addition to the housing 22 , the trigger mechanism 28 , and the spring post 34 , not seen in fig1 a , a pivot arm 40 which carries a blade 42 , and a torsion spring 44 . the pivot arm 40 , the spring post 34 , and the torsion spring 44 are located in an inner space 46 defined by the housing sections 24 and 26 . when the trigger mechanism 28 is pushed / pressed inwardly , to the left in fig1 a , the trigger mechanism 28 releases the pivot arm 40 and the torsion spring 44 rotates the pivot arm 40 such that the blade 42 passes through a slot 48 , as seen fig2 and retracts back into the housing 22 . in order to gain some insight into the dimensions of an actual unit , a typical unit has a height a of approximately 1 . 19 inches with a bottom length b of 1 . 125 inches ; the top length being slightly less than the bottom length . the unit has width c , as seen in fig2 of about 0 . 4375 inches . each of the housing sections 24 and 26 has a base 50 and four walls 52 , 54 , 56 , and 58 projecting from the base 50 . the bottom wall 54 of each of the housing sections 24 and 26 is shown in fig2 . the bottom wall 54f and 54r are joined together to define the slot 48 , through which the blade 42 passes during operation or when activated . the base 50r and the four walls 52r , 54r , 56r and 58r projecting from the base 50r of the rear housing section 24 are seen in fig3 . the four walls 52r , 54r , 56r , and 58r and base 50r define a portion of the inner space 46 . located generally where two walls join to form a corner is an opening 60 . referring to fig3 a and 3b , the rear housing section 24 has a raised portion or bulkhead 62 projecting from the base 50r . the raised portion 62 defines a convoluted cam channel 64 . located between the convoluted cam channel 64 and the slot 48 , defined by the bottom wall 54 , is a circular boss 66 which surrounds an extending rod 68 . the post 68 , as explained below , acts as a pivot point for the pivot arm 40 containing the blade 42 . referring to fig3 a and 3a , the rear housing section 24 has a second circular boss 70 defining an indentation 72 for receiving a portion of the spring post 34 . the indentation 72 has a bi - level surface 74 at the base 50r ; the bi - level surface includes a raised level 76 on either side of a lower groove 78 . in the center of the lower groove 78 is the hole 32 seen in fig1 . still referring to fig3 a , the rear housing section 24 has a post 80 that projects upwards . the post 80 engages the base 50f of the front housing section 26 as described below . the base 50r , in addition , forms a ridge 82 upon which the trigger mechanism 28 slides . the top wall 58r of the housing section 24 has a projecting member 84 , a stop member , which projects into the inner space 46 for limiting movement of the trigger mechanism 28 . the base 50f and the four walls 52f , 54f , 56f , and 58f projecting from the base 50r of the front housing sections 26 are seen in fig4 a . the four walls 52f , 54f , 56f , and 58f and base 50f define a portion of the inner space 46 . located generally in the locations where two walls join to form a corner are pins 86 , as seen in fig4 a , 4b , and 4c , which are received by the openings 60 in the rear housing section 24 . referring to fig4 a and 4b , the front housing section 26 has a semi - circular boss 88 for holding the pivot arm 40 containing the blade 50 in position , as explained below . the top wall 58f of the housing section 26 has a projecting member 84 , a stop member , which projects into the inner space 46 for limiting movement of the trigger mechanisms 28 . the front housing section 26 has a circular boss 90 defining an indentation 92 for receiving a portion of the spring post 34 as seen in fig4 a and 4c . the indentation 92 has a raised protrusion 94 at the base 50f . still referring to fig4 a , the front housing section 26 has a dimple 96 for receiving the tip of the post 80 that projects from the rear housing section 24 . the base 50f , in addition , forms a ridge 82 upon which the trigger mechanism 28 slides . referring to fig5 a , the pivot arm 40 has a shoulder 98 defined by two different level surfaces . the shoulder 98 is engaged by the torsion spring 44 , as defined below . a recess 100 is formed for part of the shoulder 98 , and is shown in hidden line . the blade 42 , a triangular blade with a cutting edge 102 and a sharpened apex 104 is coupled to the pivot arm 40 . the blade 42 may be secured to the pivot arm 40 by any conventional means and is scalpel - like in appearance and function . located on the top of the pivot arm 40 is a keeper section 106 which acts with the end of the trigger mechanism 28 to retain the pivot arm 40 in a first position prior to actuation of the skin incision apparatus 20 . referring to fig5 b , the pivot arm 40 has an extended cam follower rod 108 which extends into the convoluted cam channel 64 . the convoluted cam surface of the cam channel 64 controls the movements of the pivot arm 40 and , therefore , of the cutting edge 102 of the blade 42 when the skin incision apparatus 20 is activated . a raised boss 110 projects from the pivot arm 40 to define an elongated aperture 114 . the trigger mechanism 28 has a sloping front end 116 as seen in fig6 a which acts with the keeper section 106 of the pivot arm 40 during operation . the trigger mechanism 28 also contains a top channel 118 which abuts against the stop member 84 of the housing 22 . referring to fig6 b , the trigger mechanism 28 , also referred to as a plunger member , has a hallow section 120 through which the keeper section 106 of the pivot arm 40 passes as it moves , as explained below . fig7 is an enlarged side view of the torsion spring 44 . the spring 44 has a core 122 and a pair of legs 124 and 126 . the first leg 124 projects inwardly and bisects the core 122 . the second leg 126 extends generally out at a tangent from the core 122 . the second leg 126 has a bend or jog 128 , which facilitates assembly as discussed below . referring to fig8 a , 8b , and 8c , the spring post 34 is adapted to carry the spring 44 . the spring post 134 generally has a cylindrical shape and includes a cylindrical base portion 130 , a raised detent portion 132 , and a reduced diameter cylindrical portion 134 . the raised detent portion 132 projects from the cylindrical base portion 130 to a first end 136 . the raised detent portion 132 has a circular segment detent portion 138 projecting from the cylindrical base portion 130 . a cylindrical guide portion 140 projects from the detent portion 138 . the cylindrical guide portion 140 has an outside diameter no greater than the width of the circular segment detent portion 138 and is received by the hole 32 in the rear housing section 24 , as seen in fig1 and 3 . a turn element 142 for setting or loading the spring 34 , as described below , projects from the end of the cylindrical guide portion 140 . the turn element 142 , similar to the circular segment detent portion 138 , has a pair of parallel edges 144 spaced by circular arc edges , in a preferred embodiment , as best seen in fig8 b . the reduced diameter cylindrical portion 134 of the spring post 34 extends from the base portion 130 to a second end 146 . a slot 148 in the reduced diameter cylindrical portion 134 extends from the second end 146 to approximately the cylindrical base portion 130 . the intersection of the base portion 130 with the reduced diameter cylindrical portion 134 defines a shoulder 150 . referring to fig9 a and 9b , the skin incision apparatus 20 is assembled by placing the pivot arm 40 in the rear housing section 24 such that the extended cam follower rod 108 is received by the convoluted cam channel 64 and the elongated aperture 114 defined by the raised boss 110 , as best seen in fig9 b and 5b , receives the extending rod 68 of the rear housing section 24 . the pivot arm 40 is positioned in the first position , the actuation position , with the keeper section 106 to the left in fig9 a . prior to installing the torsion spring 44 and the spring post 34 , the leg 124 is received by the slot 148 in the reduced diameter cylindrical portion 134 of the spring post 34 , such that the core 122 of the spring 44 encircles the reduced diameter portion 134 of the post 34 . the spring 44 is located on the shoulder 150 defined by the base portion 130 and the reduced diameter cylindrical portion 134 . referring to fig9 a and 9c , the spring post 34 is positioned on the rear housing section 24 so that the raised detent portion 132 of the spring post 34 is received by the second circular boss 70 on the base 50 of the rear housing section 24 . the circular segment detent portion 138 is positioned so that it does not align with the lower groove 78 of the bi - level surface 74 , as best seen in fig9 c . the turn element 142 , in a preferred embodiment , is located in the hole 32 in the base 50 of the rear housing section 26 . the second leg 128 is received by the shoulder 98 in the pivot arm 40 . the bend or jog 128 in the leg 126 of the spring 44 reduces the chance of interference with the front housing section 26 during assembly . the trigger mechanism 28 is installed on the ridge 82 . the sloping front end 116 is positioned to engage the keeper section 106 of the pivot arm 40 . the top channel 118 is positioned to receive the stop member 84 . the keeper or safety device 38 can be installed on the trigger mechanism 28 at this time . referring to fig1 a and 10b , the front housing section 26 , is positioned on top of the rear housing section 24 such that the pins 86 , as seen in fig4 a , are received by the openings 60 , as seen in fig 9a , in the rear housing section 24 . the semi - circular boss 88 of the front housing section 26 is positioned above the pivot arm 40 , in proximity to where the blade 42 is mounted to the pivot arm 40 . the reduced diameter cylindrical portion 134 of the spring post 34 is received in the indentation 92 defined by the circular boss 90 of the front housing section 26 . the slot 148 is not aligned with the raised protrusion 94 in the circular boss 90 , at least initially . the position of the slot 148 is shown in fig9 a . with the circular segment detent portion 138 of the spring post 34 not located in the lower groove 78 of the bi - level surface 74 of the second circular boss 70 of the rear housing section 24 and the raised protrusion 94 on the front housing section 26 not received by the slot 148 of the spring post 34 , the walls 52 , 54 , 56 , and 58 of the two housing sections 24 and 26 do not engage completely , specifically walls 54 and 56 which are close to the spring post 34 . with the two housing sections 24 and 26 held together , the turn element 142 is rotated using a tool 154 , as seen in fig1 , which complements the shape of the turn element . the turn element 142 is turned clockwise as seen in fig9 and 10a , and counterclockwise as seen in fig1 . the rotation of the turn element 142 rotates the spring post 34 , therein moving the first leg 124 of the spring 44 which is received by the slot 148 in the reduced diameter cylindrical portion 134 of the spring post 34 . in the assembly , the first leg 124 is the movable end or leg to tension the spring 44 . the second leg 126 , which is received by the shoulder 98 of the pivot arm 40 , is the stationary end . the turn element 142 is rotated until the circular segment detent portion 138 of the spring post 34 aligns with the lower groove 78 of the bi - level surface 74 of the second circular boss 70 of the rear housing section 24 and the raised protrusion 94 on the front housing section 26 is received by the slot 148 of the spring post 34 . with the alignment , the walls 52 , 54 , 56 , and 58 of the two housing sections 24 and 26 do mesh , as shown in fig1 b . with the spring 44 wound and the housing 22 closed , the skin incision apparatus 20 is ready to operate . the keeper 38 is removed from the trigger mechanism 28 . the trigger mechanism 28 is pushed inward , to the left in fig1 a . as the trigger mechanism 28 is pushed , the sloping front end 116 pushes the pivot arm 40 towards the left until the pivot arm 40 clears the sloping front end 116 of the trigger mechanism 28 . with the pivot arm 40 cleared , the spring 44 pivots the entire pivot arm 40 . as the spring rotates the pivot arm 40 , the second leg 126 rotates and is the movable end , and the first leg 124 , the stationary end , is held by the spring post 34 which is held by the bi - level surface 74 of the rear housing section 24 and the raised protrusion 94 of the front housing section 26 . the pivot arm 40 moves with the extended cam follower rod 108 following the convoluted cam channel 64 . the shape of the convoluted cam channel 64 converts the generally arcuate motion of the pivot arm 40 into a linear portion for a segment of the motion of the blade 42 . the operation is such that the apex 104 of the blade 42 punctures the skin and thereafter the cutting edge 102 incises the skin . at the end of the travel , the blade 42 , including the apex 104 , is withdrawn from the skin back into the housing 22 . it is recognized that assembly could occur without assistance of humans , such as on a turntable 156 as shown in fig1 . the turntable 156 has a plurality of orifices 158 which are of a shape similar to that of the rear housing section 24 , with an additional notch for the placing of the keeper 38 . in a preferred embodiment , the turntable 156 has eight ( 8 ) orifices 158 . the turntable 158 has a plate 160 , shown in hidden line , which is generally annular and underlies all of the orifices 158 , except one as explained below , for retaining the skin incision apparatus 20 . the rear housing section 24 slides into an orifice 158 from a ramp 162 at station i . the turntable is rotated , by a motor mechanism 164 shown in hidden line , to the next position , or station . while the next rear housing section 24 is being loaded into the next orifice 158 , the pivot arm 40 is loaded by a robotic arm , not shown , at the next station ( station ii ) into the rear housing section 24 . in the next station ( station iii ), after rotation of the turntable 156 , the trigger mechanism 28 and keeper 38 are loaded as a unit . the keeper 38 is loaded on the trigger mechanism 28 prior to installation in station iii . prior to installing the torsion spring 44 and the spring post 34 , the leg 124 of the spring 44 is received by the slot 148 in the reduced diameter cylindrical portion 134 of the spring post 34 , such that the core 122 of the spring 44 encircles the reduced diameter portion 134 of the post 34 . the spring 44 is located on the shoulder 150 defined by the base portion 130 and the reduced diameter cylindrical portion 134 . the spring post 34 is positioned on the rear housing section 24 ( in station iv ) so that the raised detent portion 132 of the spring post 34 is received by the second circular boss 70 on the base 50 of the rear housing section 26 , similar to that described above with reference fig9 a and 9c . the second leg 128 is received by the shoulder 98 of the pivot arm 40 . with all the parts located on the rear housing section 24 , the front housing section 26 is positioned on the rear housing section 24 in station v . the pins 86 , as seen in fig4 a of the front housing section 26 are received by the openings 60 in the rear housing section 24 . as indicated above , the walls 52 , 54 , 56 , and 58 of the two housing sections 24 and 26 do not engage completely . the turntable rotates moving the housing sections 24 and 26 under a spring loaded plate 166 , which urges the front housing section 26 into engagement with the rear housing section 24 . the spring loaded plate 166 overlies stations vi and vii . in a preferred embodiment , no operation occurs at station vi . at the next station ( station vii ), a tool 154 , shown exploded away in fig1 , moves into engagement with the turn element 142 of the spring post 34 , as seen in fig1 and ( c , rotates the spring post 34 , therein moving the first leg 124 of the spring 44 which is received by the slot 148 in the reduced diameter cylindrical position 134 of the spring post 34 . the turn element 142 is rotated until the circular segment detent portion 138 of the spring post 34 aligns with the lower groove 78 of the bi - level surface 74 . the spring loaded plate 166 urges the front housing section into engagement with the rear housing section . the turntable 156 rotates to a final station ( station viii ) where the underlying plate 160 is not located . the skin incision apparatus 20 drops to a chute 168 or a conveyor , to move to a packaging section , not shown . it is recognized that the turntable 156 could have fewer or more stations . it is also recognized that multiple parts could be loaded at one station or a plurality of stations could have the same operation being performed and the turntable turns a plurality of orifices at one time . in addition , it is recognized that there are other methods of assembling the skin incision apparatus 20 automatically . the present invention may be embodied in other specific forms without departing from the spirit or essential attributes therefore and , accordingly , references should be made to appended claims , rather than to the foregoing specification , as indicating the scope of the invention .
an apparatus for implementing a skin incision has a torsion spring and a method of assembling the apparatus . the apparatus has a housing having a pair of housing sections , each of the housing section having a base and a plurality of walls . the housing defines an inner space and an exterior . a pivot arm is pivotally mounted to a base of a housing section . the pivot arm is guided between a first position and a second position by a follower in a cam carried by the housing . a torsion spring carried by a spring post is coupled to the arm to exert a spring force on the arm in the first position . the housing has an indentation with a raised level and a lower groove on the base for receiving a portion of the spring post . the opening through the base extends from the lower groove . the spring post has a cylindrical base portion adapted to be received by the indentation in the base and a detent portion . the detent portion has a circular segment detent portion and a turn element accessible from the exterior of the housing . the circular segment detent portion is adapted to engage the raised level of the indentation in the install position and be retained in the lower groove in the loaded position . a trigger mechanism is received in the housing and acts with the pivot arm when activated whereby the arm moves from the first position to the second position due to the spring energy .