JPH10125362A - Terminal fitting - Google Patents

Abstract

(57) [Summary] In a terminal fitting for crimping an electric wire, the cross-sectional structure of serrations of a conductor caulking piece is improved to enhance the electric wire holding force. A pair of conductor crimping pieces (4, 4) of a terminal fitting (T) have a plurality of serrations (10 ₁ , 10 ₂ , 1) on their inner surfaces.
0 ₃ is provided orthogonal to the axial direction. Among these serrations, the serrations 10 ₁ , 10 ₃ on the end side remote from the center have an inverted trapezoidal cross section, and the outer corner 11 ′ has an obtuse angle (θ ′) larger than the inner corner 11. ) To form a left-right asymmetric shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a terminal fitting to be crimped to an electric wire, and to improve the crimping characteristics thereof.

[0002]

2. Description of the Related Art Conventionally, crimp connection has been widely used as a method for connecting a terminal and a core of an electric wire. Crimping connection is a method in which a core wire is placed on the crimping part of a terminal, an external force is applied by an upper mold and a lower mold to plastically deform, and the crimping part is mechanically connected and connected. Performance) and high wire holding force. In order to secure such crimping characteristics, a groove called serration is often provided on the inner surface of the terminal.

FIG. 9 shows an example of a conventional terminal fitting. That is, the terminal fitting t has an electric contact portion 2 for a mating terminal (not shown) at the front of the substrate 1 and an electric wire crimping portion 3 at the rear.
The electric wire crimping part 3 is provided with a pair of conductor caulking pieces 4, 4 and a pair of insulator caulking pieces 5, 5, and between the conductor caulking pieces 4, 4, an inner surface thereof is provided. A plurality of serrations 6 are arranged side by side at a predetermined pitch in a direction orthogonal to the terminal axis. Figure 10 (A), (B) shows a sectional view of the serrations 6, the serrations 6 ₁ and 6 _2, 6 ₃ is an inverted trapezoidal groove has a symmetrical shape, the groove width (opening size) a, grooves Bottom width m, depth k, and edge angle θ (θ = tan ⁻¹ (a−
m) / 2k) are the same. The core wire 8 of the electric wire 7 is placed on the serration 6 and crimped with an upper mold (crimper) (not shown) and a lower mold (anvil).

The operation and effect of the serration 6 are as follows.
There is a cleaning action between the core wire and the terminal during crimping,
It is said that since the contact area between the core wire and the terminal is increased, the electric performance is improved, and further, the electric wire holding force is improved by the wedge action of the serration 6 at the angle θ.

[0005]

Although the serrations 6 have the function and effect of contributing to the improvement of the crimping characteristics as described above, the serrations 6 are particularly suitable for crimping of small-sized electric wires (for example, 0.5 sq or less). The problem is that the corner 6a becomes an edge, often damaging the core wire and greatly reducing the wire holding force. The present invention has been made in view of the above problems, and has no damage caused by the serration angle even for a small-sized electric wire, maintains a high electric wire holding force, and thereby has a stable electric connection state. It is an object of the present invention to provide a terminal fitting capable of obtaining the above.

[0006]

The present inventors have adopted the test method shown in FIG. 1 in order to clarify the mechanism by which serration causes damage. That is, the terminal fitting t
5 of A, B... E as markers in the wire crimping part 3 of FIG.
The serration of the book was stamped. Each serration has the same pitch as the dimensions, and its cross-sectional shape is shown in FIG.
Same as (A). Also, thin iron wires a, b... E corresponding to the serrations A to E were wound around the core wire 8 of the electric wire 7 to form a marker.

FIG. 2 is a graph showing the results of wire crimping, where the horizontal axis represents measurement points and the vertical axis represents elongation (mm).
Curve M represents the amount of extension of the electric wire, and curve N represents the amount of extension of the terminal. As can be seen from FIG. 2, the center of the crimped portion of both the terminal and the wire has a larger extension than the end, and the end has a smaller extension (*) in the extension between the terminal and the wire. Recognize. That is, it is presumed that the damage received by the electric wire due to the serration increases from the center to the outer end.

On the other hand, the shear force applied to the electric wire during crimping is
As shown in FIG. 3, the serration shape (opening dimension a)
It is desirable to reduce the shearing force in order to suppress the damage to the electric wire. That is, assuming that a state in which the core wire 8 is applied across the serration 6 and an external force (press) is applied is a both-end projecting beam receiving a uniform distributed load of the press load P, P = press load, a, a '= groove Opening dimension (a '
> A, b, b '= support length on the right side of the groove (b'<b), c =
When left support length of the groove (constant), the corners G, shear forces H of the left and right serrations 6, F _G = P [l (l-2b)] / 2a F _H = P [l (l- 2c)] / 2a. Therefore, the shearing force F _H ′ when one corner (the right side in the drawing) H is extended outward as H ′ and moved is F _H ′ = P [l (l−2c)] / 2a ′. 'because it is> a, F _H' a a <F _H. That is, while the cross-sectional shape of the conventional serration 6 is an inverted trapezoid having a bilaterally symmetric shape, the corner H is defined as α = a′−a
If it is shifted outward only to form a left-right asymmetric shape, the shearing force on the electric wire at the end can be reduced.

The present invention has been made on the basis of the above-mentioned findings. As described in claim 1, an electric contact portion is provided on a front portion of a substrate, and a pair of conductor caulking pieces and a pair are provided on a rear portion. A terminal crimping portion provided with an insulator crimping piece, and a plurality of serrations recessed from one side to the other of the pair of conductor crimping pieces on the inner surface orthogonal to the axial direction. In the serrations, the cross-sectional shape of the serration on the end side away from the center is inverted trapezoidal, and the outer corner is formed to be asymmetrical with a larger obtuse angle than the inner corner. .

According to the present invention, as in the above configuration, the cross-sectional shape of the serration on the end side remote from the center in the plurality of serrations is inverted trapezoidal, and the outer corner is the inner corner. Since it is formed asymmetrical with a larger obtuse angle, the shearing force on the electric wire at the serration at the end is reduced, and the damage to the core wire is reduced, so the wire holding force is strengthened by that amount, and stable electrical connection You can get the status.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific example of an embodiment of the present invention will be described below with reference to the drawings. The same components as those in the conventional example will be described using the same reference numerals. 4 and 5, the terminal fitting T is formed by coupling an electric connecting portion 2 to a front portion of a substrate portion 1 and an electric wire crimping portion 3 to a rear portion thereof. And a pair of insulator caulking pieces 5 and 5, and three serrations 10 (10 ₁ , 10 ₁ ,
10 ₂ , 10 ₃ ) are recessed at predetermined intervals in a direction orthogonal to the terminal axis.

The above is the same as the prior art, but in the present invention, as shown in FIGS. 5A and 5B, of the three serrations 10 ₁ , 10 ₂ and 10 ₃ , The serrations 10 ₂ are inverted trapezoids having a symmetrical cross section, but the serrations 10 ₁ , 10 ₃ on the end sides (both ends) are asymmetrical left and right, and the outer corners 11 ′ of each serration 10 ₁ , 10 _3. Is formed at an obtuse angle larger than the angle θ of the inner corner 11. In FIG. 5B, a,
When a '= groove width, m = groove bottom width, k = groove depth, p = pitch between serrations, the substrate 1 of the terminal fitting T is made of a copper plate, a brass plate having a plate thickness of 0.4 to 1.5 mm, In the case of a normal metal plate for a terminal such as a beryllium copper plate, a = 0.30 mm ± 0.15 mm a ′ = 0.32 mm ± 0.15 mm m = 0.20 mm ± 0.05 mm k = 0.15 mm ± 0.15 mm The range of p = 1.00 mm ± 0.15 mm θ = 104-153 ° is used, and θ ′ in the present invention is 110
A range of ~ 130 ° is appropriate. If the angle is smaller than 110 °, the shearing force cannot be reduced almost without change from the normal angle θ, and if the obtuse angle is larger than 110 °,
The effect of increasing the wire holding force due to the wedge action cannot be expected.

FIG. 6 shows a comparison between the present invention and the conventional product in terms of wire holding force and crimp resistance when a 0.5 sq wire is crimped on a brass terminal fitting T having a plate thickness of 0.5 mm in FIG. Things. However, the press load was 2.5 t, and the dimension of the serration was a = 0.30 mm,
a '= 0.32 mm, m = 0.20 mm, k = 0.15 mm,
p = 1.0 mm, θ = 108 °, θ ′ = 115 °. As is clear from FIG. 6, the resistance of the crimping portion is almost the same between the two, but the wire holding force is 130N in the present invention product compared to 110N in the conventional product, and a rise of more than 18% was observed. .

FIGS. 7A and 7B and FIGS. 8A and 8B
FIG. 3 is a schematic diagram of a micrograph showing a longitudinal cross-sectional shape of a serration portion before and after crimping of the product of the present invention and the conventional product. As is clear from the comparison between FIG. 7 and FIG. 8, in the product of the present invention in which the serrations at the center and the end are changed in cross section, the substrate 1 and the core wire 8 extend three serrations 10 _1.
Whereas almost no change in the 10 ₃ of each part, in the conventional product is thinner large elongation on both sides the substrate 1 is in the center of serration 6 _2, large at the center and the ends to the elongation of the substrate 1 and the core wire 8 It can be seen that a shift occurs.

[0015]

As described above, according to the present invention,
The wire holding force of the terminal fitting can be greatly enhanced without damaging the wire, and the reliability of the electrical connection is improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a terminal fitting test sample (sample) used for describing the present invention.

FIG. 2 is a graph showing test results for the sample of FIG.

FIG. 3 is an explanatory view of a cross-sectional shape of a serration and a shearing force.

FIG. 4 is a perspective view of a terminal fitting showing a specific example of the present invention.

FIGS. 5A and 5B are enlarged cross-sectional views of main parts of a serration portion in FIG. 4;

FIG. 6 is a graph showing the electric wire holding force and the resistance of the crimping part of the product of the present invention and the conventional product.

FIGS. 7A and 7B are schematic cross-sectional views of a serration portion before and after crimping of an electric wire according to the present invention, respectively.

FIGS. 8A and 8B are schematic cross-sectional views of a serration portion of a conventional product before and after crimping of an electric wire, respectively.

FIG. 9 is a perspective view showing an example of a conventional terminal fitting.

FIGS. 10A and 10B are cross-sectional views of main parts of a serration portion of FIG. 9;

[Explanation of symbols]

T terminal fitting 1 substrate 2 electrically contacting portion 32 wire crimping portion 4 conductor caulking pieces 5 insulator clamping pieces 10 serrations 10 ₁ to 10 ₃ serrations 11, 11 'corners theta, theta' angle

Claims (1)

[Claims] An electric contact portion is provided at a front portion of a substrate, and a wire crimping portion including a pair of conductor caulking pieces and a pair of insulator caulking pieces is provided at a rear portion, and one of the pair of conductor caulking pieces is provided. A terminal fitting formed by recessing a plurality of serrations on the inner surface perpendicular to the axial direction from the other side, wherein the cross-sectional shape of the serration on the end side away from the center in the plurality of serrations is inverted trapezoidal and A terminal fitting characterized in that the outer corners are formed to be bilaterally asymmetric at an obtuse angle larger than the inner corners.