Method of joining a bobbin and lead-out terminal in a small transformer

A method of joining a bobbin and lead-out terminal in small transformers employed in the electronic industry, which is characterized by the fact that the lead-out terminals can be mounted onto a bobbin by an insertion means, that the terminal can be mounted securely onto the bobbin lead-out manifold using bending devices, and that the mounting operation can be performed automatically in a high-speed manner and various terminal configurations can be achieved.

Description of the Invention 
Conventional methods for mounting a bobbin lead-out terminal in a small 
transformer involve fixing said lead-out terminal by molding, which is 
subject to drawbacks, as will be described below. The principal objective 
of the present invention is to present a method for mounting a bobbin 
lead-out terminal in a small transformer, with which said mounting 
operation can be performed automatically in a high-speed manner and 
various terminal configurations can be achieved in accordance with the 
applications. 
FIG. 1 depicts a conventional configuration of a bobbin with a coil 
lead-out stub H joining with a terminal P in a small transformer. The 
insertion of said terminal P into said small transformer requires several 
steps. Specifically, said terminal P is fabricated into the desirable 
shape, the terminal P obtained is placed into the injection mold cavity 
for fabricating said bobbin, and said terminal P is implanted into said 
bobbin by molding after the injection of a plastic material into said mold 
cavity. However, said method of mounting a bobbin lead-out terminal is 
undesirable in that the insertion of said lead-out terminal interferes 
with the injection molding operation and the technique is cumbersome 
because the lead-out terminal part is quite small. Accordingly, said 
method is inefficient. Moreover, the main body of said bobbin lead-out 
stub is fabricated into a certain shape for accommodating the 
configuration of said lead-out terminal (see FIGS. 2 and 3), thereby 
requiring different molds for different configurations, which is not 
costeffective. The present invention presents a method for mounting a 
bobbin lead-out terminal in a small transformer by inserting said terminal 
into a lead-out manifold, with which various lead-out manifold 
configurations can be employed, production efficiency can be increased 
appreciably, various lead-out terminal configurations can be used, 
depending on the applications, and the number of dies needed is reduced, 
thereby lowering operation costs. 
A description including figures is presented below for explaining the 
technical means employed for achieving the aforesaid merits and objectives 
pertaining to the present invention.

DESCRIPTION OF THE FIGURES 
FIG. 1: A conventional means of mounting a bobbin lead-out terminal. 
FIGS. 2 and 3: Practical examples pertaining to the present invention. 
FIG. 4: A three-dimensional drawing showing a bobbin fabricated in 
accordance with the present invention. 
FIG. 5: A side view of the bobbin fabricated in accordance with the present 
invention. 
FIG. 6: A drawing showing the operation of the mechanism employed for 
inserting lead-out terminals pertaining to the present invention. 
FIGS. 7, 8 and 9: Drawings showing the process of bending the lead-out 
terminal. 
The present invention offers a method for mounting a terminal 3 into a 
bobbin lead-out wire-stab manifold 2 of a small transformer bobbin 1, as 
shown in FIG. 4. Said bobbin 1 is fabricated by injection molding, and the 
bobbin body 11 is to be wrapped with an enamel-insulated wire. The two 
ends of said bobbin body 11 are each equipped with a manifold 2 possessing 
a series of wire slots 21 and insertion holes 22 aligned in an orderly 
manner, with said manifold 2 being positioned vertically with respect to 
said bobbin body 11. As shown in FIG. 5, said manifold 2 is equipped with 
a series of wire slots 21 for accommodating the bobbin lead-out wire 
stabs, and said wire slot 21 runs in the length direction of said bobbin 
body 11. Said wire slot 21 possesses an opening that faces toward a 
corresponding circuit board 4, so that the mounting surface 12 is equipped 
with H-shaped tunnel-like openings for accommodating the bobbin lead-out 
wire stab 5 from said bobbin 11. Said lead-out wire stab 5 coming out from 
said wire slot 21 is to be soldered onto a terminal. In addition, said 
bobbin lead-out wire-stab manifold 2, which is made of a solid piece of 
plastic, is equipped with insertion holes 22 that run along the length 
direction thereof in the middle of said mounting surface 12. Said 
insertion hole 22 for accommodating said terminal 3 is positioned 
vertically with respect to said mounting surface 12. Said manifold 2 is 
also equipped with a mounting surface 23 for said terminal 3 to be 
mounted, which requires a bending operation. Said mounting surface 23 is 
positioned at a location that corresponds to said insertion hole 22, and 
faces away from said bobbin body 11 in a parallel direction. With the 
aforesaid configuration, said terminal 3 is bound upon being inserted into 
said insertion hole 22. The binding strength depends on factors such as 
the degree of fitness between said insertion hole 22 and terminal 3 and 
the characteristics of the plastic material used for fabricating said 
manifold 2 (e.g., compressibility, tear resistance, etc.). 
The method of inserting said terminal 3 into said bobbin 1 is described 
below together with FIG. 6. A sending device 6 is employed to send said 
bobbin 1, which is obtained by injection molding, into the loading 
platform 62 of a piston stroke device 61. Said loading platform 62 is 
designed to house said bobbin 1. A set of terminal-wire rolls 31 is placed 
above the piston-stroke movement line of said piston stroke device 61. 
Each of said terminal-wire rolls 31 is aligned with the center of said 
insertion hole 22 and placed on a turnable axle 311. A cutting device 7 is 
placed near the bobbin lead-out wire-stab manifold 2 between said wire 
roll 31 and bobbin 1. Said cutting device 7 consists of a platform bed 71, 
sliding press plate 72 and cutter 73. Said sliding press plate 72 can 
slide along said platform bed 71, and a gap in said sliding press plate 72 
allows said the terminal wire 32 to be inserted through. According to the 
movements of the aforesaid mechanisms, said terminal wire 32 is inserted 
through said cutting device 7 until the terminal-wire stub 321 is near 
said insertion hole 22, and the terminal-wire stub 321 is held in place, 
aligning with the center of said insertion hole 22. Next, said piston 
stroke device 61 lifts said bobbin 1 to a position, so that said terminal 
wire 32 can be inserted into the insertion hole 22. Afterward, the 
terminal wire is cut to an appropriate length. 
The operation steps of bending the resulting terminal 3 are described below 
together with FIGS. 7, 8 and 9. These figures concern a practical example 
of a terminal configuration shown in FIG. 2. The bending operation is 
performed by a machine. A set of dies 8 is employed to bend one end of 
said terminal 3 held by said manifold 2. Both the male and female dies 8 
are equipped with curved edges, so that a curved terminal 3 is obtained. 
Next, a preliminary bending operation is performed, so that a more precise 
bending angle can be achieved in subsequent bending operations. As shown 
in FIG. 8, a set of stamping devices 81 and 82 each with a tilted surface 
is employed to cause the bases 301 and 302 of the two ends of said 
terminal 3 held by said manifold 2 to be bent at a 45.degree. angle. The 
final bending operation is depicted in FIG. 9. A set of stamping devices 
83 and 84 each with a fiat surface is employed to cause said terminal 3 to 
wrap around said manifold 2 securely. Since the terminals are positioned 
in an orderly manner and each bending step involves the employment of an 
appropriate set of stamping dies, the shape and dimensions of the 
resulting terminals after bending are uniform and orderly, facilitating 
the installation of the resulting transformer onto a circuit board evenly 
by soldering. 
If demanded by the design of a circuit board, the bobbin body can also be 
placed into a cavity 91 in a circuit board 9 for reducing the height of 
said bobbin. In this configuration, the terminal 3 is bent into an "L" 
shape, as shown in FIG. 3. In summary, the terminals can be formed into 
various shapes by using different stamping dies and techniques. The 
emphasis of the present invention is to offer a method for mounting a 
bobbin lead-out terminal in a small transformer that involves a set of 
lead-out wire-stub manifolds equipped with insertion holes into which 
terminals can be inserted in a mass production manner, with which various 
lead-out manifold configurations can be employed, production efficiency 
can be increased appreciably, various lead-out terminal configurations can 
be used, depending on the applications, and the number of dies needed is 
reduced, thereby lowering operation costs. 
The objective of the present invention of presenting a method of mounting 
terminals into the manifold of a bobbin by insertion is to solve the 
problems associated with conventional means of mounting lead-out terminals 
by molding. An injection mold and several stamping dies are employed in 
accordance with the method pertaining to the present invention, with which 
the mounting operation can be performed automatically at a high-speed 
manner, various terminal configurations can be achieved, and the shape and 
dimensions of the resulting terminals after bending are uniform and 
orderly, facilitating the installation of the resulting transformer onto a 
circuit board evenly by soldering.