Shearing mechanism in a machine for attaching a terminal to a conductor

A machine is disclosed for inserting terminals into cavities of a bobbin to terminate the ends of electrical windings. The machine includes a shear mechanism that separates the terminals from the carrier strip and then guides the terminals during insertion thereof. The shear mechanism includes a pair of links that form a toggle having a center pivot that is attached to the piston rod of an air cylinder. Movement of the toggle links in turn moves a pivoting lever that causes the shear blades to reciprocate. As the piston rod is made to extend, the links straighten and then pass center a small amount until a stop setscrew is engaged. As the links straighten the shear blades enter the die and sever the segments of carrier strip from the terminals. As the links pass over center the shear blade is partially withdrawn so that it clears features projecting from the sides of the terminals while a guide portion of the blade remains in guiding engagement with the severed terminals during insertion thereof.

The present invention relates to machines for attaching a terminal to the 
ends of magnet wire wound around a bobbin, and in particular to a 
mechanism for separating the terminal from the carrier strip and guiding 
it during insertion into the bobbin. 
BACKGROUND OF THE INVENTION 
Existing machines for terminating the ends of electrical windings of 
bobbins must be able to accommodate different styles and types of 
terminals. In all cases the terminal is severed from the carrier strip by 
a cutting blade and then it is inserted into a terminal receiving cavity 
of the bobbin. During insertion, the cutting blade remains extended to 
guide the loose terminal. In cases where the terminal has a lug or other 
projection extending beyond the sides of the terminal, this projection 
must be cleared by the cutting blade during insertion. This is 
accomplished by withdrawing the cutting blade, after severing, just enough 
to clear the projection yet the blade remains close enough to guide the 
terminal. The mechanism for performing the withdrawal is usually a cam and 
follower structure. Typically, a member having a cam slot is attached to 
the end of the piston rod of the air cylinder that actuates the cutting 
blades. A follower that is attached to the end of a pivoting member 
engages the cam slot, the other end of the pivoting member being coupled 
to the cutting blades for operation thereof. As the piston rod of the air 
cylinder extends, the cam slot causes the follower to move the end of the 
pivoting member so that the cutting blades extend and sever the carrier 
strip then withdraw a specific amount. The terminal is then inserted and 
the air cylinder reversed so that the follower rides back along the cam 
slot reversing the withdrawal motion and then retracting the cutting 
blades. The cam and follower mechanism in such machines is expensive to 
manufacture and is usually different for different terminal applications, 
thereby requiring setup time. What is needed is a machine that has a 
shearing mechanism that is adjustable so that the amount of cutting blade 
withdrawal can easily be adjusted to a desired amount or to no withdrawal 
in cases where there are no projections. 
SUMMARY OF THE INVENTION 
A machine is disclosed for attaching terminals to the ends of an electric 
winding of a bobbin. The machine has a frame and a shearing mechanism 
supported by the frame for separating the terminals from the carrier strip 
and for guiding the terminals during insertion thereof into the bobbin. 
The shearing mechanism includes a die and a punch arranged for 
reciprocating motion toward and away from the die. The punch assumes a 
first position away from the die, a second position in mated shearing 
engagement with the die, and a third position wherein the punch is 
adjacent to but spaced from the die and is in guiding relationship with 
the terminal. The actuator means is operable in a forward direction to an 
extended position and a reverse direction to a retracted position for 
effecting the reciprocating motion of the punch. When the punch is in the 
first position the actuator means is in the retracted position, when the 
punch is in the third position the actuator means is in the extended 
position, and when the punch is in the second position the actuator means 
is between the retracted and extended positions.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
There is shown in FIGS. 1 and 2 a machine 10 having a frame, a portion of 
which is shown at 12, a terminal shearing and guiding mechanism 14, and a 
terminal insertion mechanism 16, both of which are coupled to the frame. A 
typical bobbin 18 having an electrical winding 20 and terminal receiving 
cavities 22 is shown adjacent the machine 10 in position for receiving a 
terminal 24. The bobbin 18 is supported and positioned on tooling, not 
shown, that is specifically provided for each different bobbin 
application. A typical terminal 24 that is used to terminate the ends of 
the winding 20 is shown in FIG. 3. The terminals 24 are provided in strip 
form in the usual manner, interconnected by a two segment carrier strip 
28. Each terminal has an insulation displacement slot 30 for receiving an 
end of the winding 20 and making electrical contact therewith. The other 
end of the terminal,in the present example, has a spade lug 32 projecting 
outwardly therefrom for interconnecting to other electrical components. 
This spade lug 32 is sometimes wider than the width of the body of the 
terminal 24, and therefore must be cleared by the shearing tool during 
severing and insertion of the terminal. This will be explained in more 
detail below. 
The shearing and guiding mechanism 14, as shown in FIGS. 1 and 2, includes 
an L-shaped lever 34 that is pivotally attached to the frame 12 by means 
of the pin 36. One end 38 of the L-shaped lever is bifurcated to receive 
an end of a link 40 and the two are pivotally attached by means of the pin 
42. The other end of the link 40 is pivotally attached to an end of an 
H-shaped link 44 by means of the pin 45, and the other end of the H-shaped 
link is pivotally attached to a projection 48 of the frame 12 by means of 
the pin 50, thereby forming a pair of toggle links. A linear actuator 52, 
an air cylinder in the present example, is attached to a trunion 54 which 
is pivotally attached to the frame 12 by means of a pair of pins 56. A 
clevis block 58 is attached to the piston rod of the cylinder 52 and has a 
hole through which the pin 45 passes, thereby coupling the piston rod of 
the air cylinder to the center pivot of the toggle links 40 and 44. A 
U-shaped member 60 having a setscrew 62 threaded therethrough is secured 
to the trunion 54 by means of the screws 64, the setscrew being in 
alignment with the clevis block 58 so that as the piston rod of the 
cylinder 52 is extended, the clevis block will abut the setscrew thereby 
limiting the travel of the piston rod. The other end 66 of the L-shaped 
lever is coupled to a shear blade holder 68 by means of a pin 70. The pin 
70 extends through an elongated hole 72 formed in the end of the holder 68 
and is sized to slide back and forth within the hole 72 with little or no 
appreciable play in the vertical direction, as viewed in FIG. 1. The 
holder 68 is attached to a movable member 74 of a slide assembly by the 
screws 76 while the stationary member 78 of the slide assembly is attached 
to the frame 12 by the screws 80 so that the holder will undergo 
reciprocating motion when the air cylinder 52 is actuated in both 
directions. 
As shown in FIG. 1 a shear blade or punch assembly 82 is positioned 
directly above the terminal 24. A mating die block 84 is positioned below 
the terminal and supports it during separation of the terminal from the 
carrier strip. The shear blade assembly 82 and the die block assembly 84 
are shown in detail in the exploded parts view of FIG. 4. There, the shear 
blade holder 68 is shown in relation to the shear blade assembly 82 which 
includes a pair of identical shear blades 86 separated by a spacer 88 
having a thickness that is substantially the same as the width of the 
terminal 24. A holder block 90 is arranged adjacent the right most shear 
blade 86 and another holder 92, which is L-shaped, is arranged on the 
opposite side of the left most shear blade with a spacer block 94 
therebetween. The parts 86, 88, 90, 92, and 94 are stacked together and 
positioned within a cavity 96 formed in the holder 68. A pair of roll pins 
are inserted into holes that are formed through all of the parts, 
including the holder 68, to position the shear blades in the desired 
alignment with their top surfaces 100 in abutting engagement with the top 
of the cavity 96. A pair of screws 102 extend through clearance holes in 
the block 68 and into threaded holes 104 in the holders 90 and 92. 
The die block assembly 84, as viewed in FIG. 4, includes a right guide 
member 106 having a U-shaped opening 108 for receiving and guiding the 
strip of terminals 24 and a left guide member 110 for guiding the left 
most terminal after separation from the carrier strip. An outer shear 
block 114 is positioned adjacent the right guide member 106 and a pair of 
inner shear blocks 116 are positioned between the outer shear block and 
the left guide member 110. A pair of stripper plates 118 and 120 are 
positioned directly above the two inner shear blocks 116 to hold the 
terminals in place after shearing and during withdrawal of the shear 
blades 86. A first carriage 122 has an L-shaped nest 124 for receiving and 
positioning the die block assembly 84. A pin 126 and a pair of screws 128 
secure the assembly to the first carriage 122, the screws threaded into 
holes in the carriage. A tool guide block 130 having four openings 132 
therethrough is also part of this assembly and is positioned in front of 
the two inner shear blocks 116 and secured in place with a screw 134 that 
extends through the right and left guide members 106 and 110 and into a 
threaded hole in the first carriage 122. The purpose of the tool guide is 
to guide a pair of inserter blades 136 and a pair of cutoff blades 138 as 
shown in FIG. 4. There, a second carriage 140 is shown having a cutout 142 
for receiving a pair of tool holders 144 and a clamping block 146, which 
are secured within the cutout by means of the screws 148. Each tool holder 
144 has a pair of slots 150 sized to receive the ends of the insert blades 
136 in the two lower slots and the two cutoff blades in the two upper 
slots. The depth of the slots 150 is less than the width of the blades so 
that when the screws 148 are tightened the blades 36 and 138 are rigidly 
clamped in place. The other ends of the blades 136 and 138 are aligned 
with the openings 132 in the guide block 130. As best seen in FIG. 1, the 
first and second carriages 122 and 140 are slidingly coupled together by 
means of a slide 152 which permits relative movement of the two carriages 
so that the two insertion blades and the two cutoff blade can be passed 
through the openings 132 for inserting the terminal into the bobbin and 
then withdrawn. An air cylinder 154 has its housing attached to the second 
carriage 140 and its piston rod 156 coupled to the first carriage 122. In 
operation, the cylinder 154 is normally energized so that the piston rod 
156 is in its extended position. as shown in FIG. 1, for a purpose that 
will be explained. The assembly of the two carriages 122 and 140 and the 
air cylinder 156 is arranged on another slide 158, which has its 
stationary portion attached to the frame 12 of the machine. The slide 158 
is arranged so that the insertion blades 136 will push the terminals 24 
toward the bobbin 18 and into the terminal receiving cavities 22. This is 
accomplished by an air cylinder 160 having its housing attached to the 
frame 12 and the end of its piston rode 162 coupled to the carriage 140. 
There is shown in FIG. 5 an enlarged view of the tip of the shear blade 86 
having a cutting portion 164 and a guide portion 166. The cutting portion 
has a leading end 168 that is sized to fit between the two carrier strip 
segments 28. A lead in chamfer 170 is provided on the end 168 to self 
center the terminal strip with the shear blade. A pair of cutting edges 
172 angle outwardly from each side of the end 168 and interact with the 
shear blocks 114 and 116 to sever the segments 28 and separate the 
terminals 24 from the strip. The guide portion 166 is slightly undercut to 
provide sufficient clearance between the guide portion and the terminals 
24 to prevent binding when the terminals are pushed by the blades 136 into 
the bobbin cavities. 
The operation of the machine 10 will now be described with particular 
reference to FIGS. 1 and 6 through 10. The starting position of the 
shearing and insertion mechanisms are as show in FIG. 1 with the cylinders 
52 and 160 retracted and the cylinder 154 pressurized to its extended 
position. A bobbin 18 is arranged in position as shown in FIG. 1. A strip 
of terminals is loaded into the machine so that a pair of terminals 24 are 
in position over the shear blocks 116, as best seen in FIG. 8. The air 
cylinder 52 is then pressurized to extend its piston rod. As the toggle 
links 40 and 44 reach the position shown in FIG. 6, where the axes of the 
pivot pins 42, 45, and 50 are in a common plane, the lever arm 34 has 
pivoted a maximum amount about its pivot pin 36 thereby moving the tool 
holder 68 and the shear blades 86 downwardly to the position shown in FIG. 
9. As the cutting edges 172 passed the upper surfaces of the shear blocks 
114 and 116, the four segments 28, two segments between each terminal, 
were severed thereby separating the two terminals 24 from the carrier 
strip. As the piston rod of the cylinder 52 continues to extend, the 
center pivot pin 45 of the toggle links moves above the common plane where 
the top of the clevis 58 abuts the setscrew 62 thereby preventing further 
upward movement, as shown in FIG. 7. This movement of the pivot pin 45 
over center causes the lever arm 34 to reverse direction and withdraw the 
shear blades 86 to a position slightly above the shear blocks 114 and 116, 
as shown in FIG. 10. While the guide portion 166 of each blade 86 remains 
within the space between adjacent severed terminals 24, the chamfered tip 
170 is clear of the spade lugs 32. While the piston rod of the cylinder 52 
remains extended, the air cylinder 160 is pressurized causing the two 
carriages 122 and 140 to move along the slide 158 toward the bobbin 18, as 
best seen in FIG. 1. This movement continues until the faces of the 
carriage 122 and the guide block 130 engage the face of the bobbin 18 and 
stop further movement of the carriage 122. However, since the air cylinder 
160 is larger than the cylinder 154, the smaller one is overpowered 
allowing the second carriage 140 to move with respect to the first 
carriage 122 along the slide 152. This carries the insertion blades 136 
and the cutoff blades 138 forward, picking up the two terminals and 
pushing them between the guide portions 166 toward and into the openings 
132 of the guide block 130, through the guide block and into the terminal 
receiving cavities 22 of the bobbin 18. As the terminals seat in the 
cavities 22 the ends of the windings 20 are forced into the insulation 
displacement slots 30 of the terminals and the cutoff blades 138 trim off 
the excess wire ends. The pressurization of the air cylinder 160 is then 
reversed and the second carriage 140 withdrawn, thereby withdrawing the 
blades 136 and 138 to their original starting position relative to the 
first carriage 122 as the first carriage is held in engagement with the 
bobbin 18 by the air cylinder 154. As the cylinder 160 continues to 
retract, the cylinder 154 reaches its full extension allowing the first 
carriage to withdraw away from the bobbin and both first and second 
carriages to return to their starting positions shown in FIG. 1. The 
piston rod of the air cylinder 52 is then retracted thereby returning the 
toggle links 40 and 44 to their starting position shown in FIG. 1. The 
bobbin 18 can then be moved to place empty cavities 22 in position and the 
process repeated. 
It will be appreciated that the tips of the shear blades 86 must clear the 
spade lugs 32, as viewed in FIG. 10, while the terminals are pushed by the 
insertion blades and yet the guide portion 166 must remain in guiding 
position with respect to the box portion 174 of the terminal 14. The 
position of these tips is governed by the extension of the piston rod of 
the air cylinder 52, which is limited by the setscrew 62. With the piston 
of the air cylinder fully extended, as shown in FIG. 7, the position of 
the tips of the shear blades 86 with respect to the shear blocks 114 and 
116, as shown in FIG. 10, can be easily adjusted by adjusting the setscrew 
62. 
An important advantage of the present invention is that the shearing motion 
of the shear blades and their subsequent partial withdrawal for insertion 
of the terminal is accomplished with a single stroke of the air cylinder. 
This permits a much simplified structure of the actuating mechanism. 
Additionally, this conveniently permits a dwell prior to the return stroke 
so that the terminal can be inserted into the bobbin, without any 
additional structure that would otherwise be required to provide the delay 
.