GB2340674A

GB2340674A - Simultaneous crimping and ultrasonic soldering

Info

Publication number: GB2340674A
Application number: GB9918750A
Authority: GB
Inventors: Toshida Murayama; Yasumichi Kuwayama
Original assignee: Yazaki Corp
Current assignee: Yazaki Corp
Priority date: 1998-08-10
Filing date: 1999-08-09
Publication date: 2000-02-23
Anticipated expiration: 2019-08-09
Also published as: JP3901855B2; DE19937100C2; GB2340674A8; GB9918750D0; JP2000058153A; GB2340674B; DE19937100A1

Abstract

To join a terminal 20 to the braid 13 of a cable 10, the outer insulation 14 is removed and the cable placed within U-shaped arms 21 of the terminal. These arms have solder 23 pre-applied. An ultrasonic horn 30 and anvil 31 are then used to crimp the arms round the braid whilst at the same time melting the solder 23 to give a secure join (see figure 2C). The U-shaped arms may include an annular protrusion (21b, Fig 4) to keep the molten solder in. The connection may be made at the end of the cable 10 or at a point along its length (see figures 3A, 3B).

Description

2340674 SHIELDED CABLE JOINING STRUCTURE, JOINING METHOD, AND SHIELD

TERMINAL FOR USE IN SAME

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a shielded cable joining structure, a method for joining a shielded cable, and a terminal for use in joining a shielded cable.

2. Description of the Related Art

A termination structure for the above-noted type of shielded cable is disclosed in the Japanese Unexamined Patent Application publication H7 201383, in which a shielded cable is formed by an inner core wire that is made of a conductor, an inner insulation covering that covers the inner core wire, a braid that is provided around the periphery of the inner insulation covering, and an outer insulation covering that covers the braid.

In the above-noted related art, part of the outer insulation covering at the end part of the shielded cable is removed, the inner insulation covering and braid are separated from one another, and the ends of the inner core wir 1 c that is exposed at the end part of the inner insulation covering and the braid are each connected by means of a terminal fixture. Before crimping the terminal fixture onto the end of the braid, the end part of the braid is bundled together by heat-shrink tubing that contracts by the application of heat.

In the above-noted termination structure for a shielded cable, however, because the terminal fixture is crimped onto the end of the braid after the braid 1 is separated from the inner insulation covering, not only is there a danger of damaging the braid when performing the crimping operation, but also there is a part thereof that is not shielded. Additionally, because it is essential to have a bundling member such as heat-shrink tubing in order to bundle together the end part of the braid, the task of termination was cumbersome.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to improve on the above-noted drawbacks in the related art, by providing a shielded cable joining structure and method, and a shield terminal whereby it is easy to achieve a reliable joining of a shield terminal to the exposed part of the braid, without damaging the braid.

In order to achieve the above-noted object, from the first aspect of the present invention, there is provided a joining structure for a shielded cable, comprising:

an inner core wire made of a conductor; an inner insulation covering that covers the inner core wire; a braid that is provided around the outside periphery of the inner insulation covering; an outer insulation covering that covers the braid, the outer insulation partially removed to expose a part of the braid; a shield terminal having a crimping part crimped to the exposed part of the braid; and a low-melting-point joining substance disposed between the exposed part of the braid and the crimping part of the shield terminal; wherein a fused joint between the crimping part of the shield terminal and the exposed part of the braid is formed by applying ultrasonic vibration to the crimping part to melt the low-melting-point joining substance.

2 In this joining structure, with the shield terminal crimped to an exposed part of the braid that is exposed by removing part of the outer insulation covering at a grounding position of the shielded cable, ultrasonic vibration is used to melt the low-melting-point joining substance that was applied to the crimped part, thereby forming a fused joint between the crimped part of the shield terminal and the exposed part of the braid.

In this shielded cable joining structure, because heat (internally generated heat) is generated only at the crimped part of the shield terminal by means of ultrasonic vibration, damage to the braid by heat is minimized.

Additionally, by using a low-melting-point joining substance, a fused joint is easily formed between the crimped part of the shield terminal and the exposed part of the braid, thereby improving the reliability of the joint. In addition, because there is no need to separate the braid from the inner insulation covering, the shielding performance is improved.

From the second aspect of the present invention, there is provided a method for joining a shielded cable, whereby a shield terminal with a low melting point substance is joined to a prescribed grounding position of the shielded cable, which is formed by an inner core wire made of a conductor, an inner insulation covering that covers the inner core wire, a braid that is provided around the outside periphery of the inner insulation covering, and an outer insulation covering that covers the braid, the method comprising steps of:

removing part of the outer insulation covering at the grounding position of the shielded cable so as to expose part of the braid; applying a crimping part of the shield terminal to the exposed part of the braid; and using an ultrasonic horn to apply ultrasonic vibration to the crimping part of the shield terminal to which the low-melting-point joining substance 3 has been applied while performing crimping thereof, so as to cause internal generation of heat, which melts the low-melting-point joining substance and forms a fused joint between the shield terminal crimped part and the braid of the shielded cable.

In the above-noted method for joining a shielded cable, because a fused joint is formed between the crimped part of the shield terminal and the braid while crimping the crimping part after the crimping part of the shield terminal is applied to an exposed part of the braid, it is possible to simplify the processing step and improve the work efficiency.

Rom the third aspect of the present invention, there is provided a shield terminal which is joined to a prescribed grounding position of a shielded cable which is formed by an inner core wire made of a conductor, an inner insulation covering that covers the inner core wire, a braid that is provided around the outside periphery of the inner insulation covering, and an outer insulation covering that covers the braid, via a low-melting-point joining substance that is melted by means of ultrasonic vibration, the shield terminal comprising:

a crimping part with a low-melting-point substance, crimped to the braid of the shielded cable; and a connecting part that is connected to a grounded part that is joined to the crimped part.

In the above-noted shield terminal, the crimping part enables easy and reliably joining to a grounding position at the end of the shielded cable or at, for example, an intermediate position thereof.

The shield terminal may further comprises an annular protrusion disposed on an outside periphery of an inner surface of the crimping part.

In the above-noted shield terminal, when a low-melting-point substance that is applied to the inner surface of the crimping part of the shield 4 terminal is melted, the flow of the melted low-melting-point substance to the outside is reliably prevented by the annular protrusion. The result is a great improvement in the electrical connection and strength of the connection between the crimped part of the shield terminal and the braid of the shielded 5 cable.

In the shield terminal the crimping part may be substantially U-shaped and formed so as to be opposing in mutual offset.

In the above-noted shield terminal, because the braid is held within the crimping part without the occurrence of a space between the ends of the crimping part, which is approximately U-shaped, damage to and broken connections in a slender braid are reliably prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1A is a perspective view that shows an embodiment of a joining structure for a shielded cable according to the present invention, Fig. 1B is a cross-section view along the cutting line X-X indicated in Fig. 1A, and Fig. 1C is a perspective view of a shield terminal that is used in this joining structure.

Fig. 2A is a perspective view of the shielded cable to which the joining structure of Fig. 1A is applied, Fig. 2B is a perspective view that shows the condition before the shielded terminal is joined to the shield cable, and Fig. 2C is a perspective view that shows the condition after joining the shielded cable to the shield terminal.

Fig. 3A is a perspective view that shows the condition of a exposed braid at an intermediate position of the above-noted shielded cable, and Fig. 3B is a perspective view that shows the condition in which the above- noted shield terminal is joined to the exposed part of the braid at an intermediate position.

Fig. 4 is a perspective view of another embodiment of a shield terminal according to the present invention.

Fig. 5 is an enlarged partial cross-section view that shows the main part of the embodiment of the shield terminal shown in Fig. 4.

Fig. 6 is a cross-section view that shows the main part of a joining structure for a shielded cable that uses the shield terminal embodiment shown in Fig. 4.

Fig. 7A is a perspective view that shows another embodiment of a shielded cable joining structure according to the present invention, Fig. 713 is a cross-section view along the cutting line Y-Y that is shown in Fig. 7A, and Fig.

7C is a perspective view that shows another embodiment of a shield terminal used in this shielded cable joining structure.

Fig. 8A is a perspective view that shows the shielded cable to which an embodiment of the joining structure different from above is applied to a shielded cable, Fig. 8B is a perspective view that shows the condition in which the different embodiment of a shield terminal is joined to the shielded cable, and Fig. 8C is a perspective view that shows the condition after the above joining operation is performed.

Fig. 9A is a perspective view that shows the condition of an exposed part of the braid at an intermediate position of the shielded cable according to a different embodiment from the above, and Fig. 9B is a perspective view that shows the condition after the different embodiment of shield terminal is joined to the exposed part at the intermediate position of the shielded cable.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention are described in detail below, with reference to the accompanying drawings.

Fig. 1A is a perspective view that shows an embodiment of a joining 6 structure for a shielded cable according to the present invention, Fig. IB is a cross-section view along the cutting line X-X indicated in Fig. 1A, Fig. 1C is a perspective view of a shield terminal that is used in this joining structure, Fig.

2A is a perspective view of the shielded cable to which the joining structure of Fig. 1 is applied, Fig. 2B is a perspective view that shows the condition before the shielded terminal is joined to the shield cable, and Fig. 2C is a perspective view that shows the condition after joining the shielded terminal to the shield cable.

As can be seen from Figs. 1A, 1B, 2A, 2B, and 2C, the shielded cable 10 to which the joining structure of the present invention is applied is formed by an inner core wire 11, which is made of a conductor, an inner insulation covering 12 that covers the inner core wire 11, a braid 13, which is provided around the periphery of the inner insulation covering 12 and which is woven in a cloth-like manner from a plurality of slender bare wires, and an outer insulation covering 14, which covers the braid 13. Part of the outer insulation covering 14 at end A (the grounding position) of the shielded cable 10 is removed, so that part of the inner core wire 11 is exposed. A pair of crimping parts 15a, 15a of a terminal fixture 15 are crimped around the exposed end A of the inner core wire 11. The male tab (connection part) 15b of the terminal fixture 15 makes contact with, for example, a mating female terminal (not shown in the drawing) which protrudes within a hood 16a of a connector 16.

Additionally, a part of the braid 13 between the outer insulation covering 14 and the inner insulation covering 12 at the end A of the shielded cable 10 is also exposed. A shield terminal 20 can be freely joined to this exposed part of the braid 13. As shown in Fig. 1C, the shield terminal 20 has a low-melting-point substance 23 applied to it, and this shield terminal 20 has a pair of crimping parts 21, 21 that are approximately U-shaped when viewed from the front and which are crimped onto and make a metallic joint with the 7 braid 13, and male tab (connection part) 22 which is L-shaped when viewed from the top, is formed as one with one end of the bottom center part between the pair of crimping parts 21, 21, and which is connected to a mating grounding part that is not shown in the drawing. The crimping parts that form the pair of crimping parts 21, 21 are bent so as to be in mutual opposition, and a low-melting-point substance 23, such as solder, which metal by means of ultrasonic vibration, is applied to inner surfaces 21a thereof.

Turning to the method for joining the shield terminal 20 to the shielded cable 10, first, as shown in Fig. 2A, part of the outer insulation covering 14 at end A, which is the grounding position, of the shielded cable 10 is removed, so as to expose part of the end of the braid 13. Next, as shown in Fig. 2B, the exposed part of the braid 13 is inserted into the pair of crimping parts 21, 21 of the shield terminal 20, and the shield terminal 20 is then held between the arc-shaped bottom part of an ultrasonic horn 30 and the top part of an anvil 31, ultrasonic vibration being applied thereto while applying pressure. By crimping while applying ultrasonic vibration to the pair of crimping parts 21, 21 of the shield terminal 20 using the ultrasonic horn 30 and the anvil 30, the ultrasonic energy thereof causes the internal generation of heat, thereby melting the low-melting-point substance 23 that was applied to pair of crimping parts 21, 21. The melted low-melting-point substance 23 forms an ultrasonic fused bond between the crimped pair of crimping parts 21, 21 of the shield terminal 20 and the exposed part of the braid 13. When this joint is made, because the melted low-melting-point substance 23 encroaches between the weaving of the braid 13, there is a great joining force between the braid 13 and the crimped pair of crimping parts 21, 21 of the shield terminal 20. Next, the terminal fixture 15 that has been crimped on the exposed end A of the inner core wire 11 of the shielded cable 10 and the shield terminal 20 that was joined to end A of the braid 13 are inserted into the hood part 16a of the 8 connector 16.

In this manner, because internal heat is caused to be generated only within the pair of crimping parts 21, 21 of the shield terminal 20, using the ultrasonic vibration from the ultrasonic horn 30, it is possible to minimize the 5 damage to the braid 13 at the end A of the shielded cable 20 caused by heat. Additionally, because the melted low-melting-point substance 23 that is used encroaches between the weaving of the braid 13, it is easy to make a fusion joint between the pair of crimped parts 21, 21 of the shield terminal 20 and the exposed part of the braid 13, and possible to provide a significant improvement in the reliability of this joint. Additionally, because there is no need, as there was in the past, to separate the braid from, for example, the inner insulation covering 12, the shielding performance can be improved.

Because a fused joint is formed between the pair of crimping parts 21, 21 of the shield terminal 20 and the braid 20 while crimping the crimping parts 21, 21 after the crimping part of the shield terminal is applied to an exposed part of the braid, it is possible to simplify the processing step and improve the work efficiency.

Fig. 3A1s a perspective view that shows the condition of a exposed braid 13 at an intermediate position (grounding position) of the shielded cable 20, and Fig. 3B is a perspective view that shows the condition in which the shield terminal 20 is joined to the exposed part of the braid 13 at an intermediate position.

As shown in Fig. 3A and Fig. 3B, part of the outer insulation covering 14 at an intermediate position B of the shielded cable 10 is removed, so as to expose part of the braid 13, and a fused joint is made while crimping the pair of crimping parts 21, 21 of the shield terminal 20 onto the exposed part of the braid 13. By doing this, it is easy to make a reliable joint between shield terminal 20 and the end A or any grounding position such as the intermediate 9 part B of the shielded cable 10, via the pair of crimping parts 21, 21 of the shield terminal 20.

Fig. 4 is a perspective view of another embodiment of a shield terminal 20' according to the present invention, Fig. 5 is an enlarged partial cross- section view that shows the main part of the embodiment of the shield terminal 20' that is shown in Fig. 4, and Fig. 6 is a cross-section view that shows the main part of a joining structure for a shielded cable that uses the shield terminal 20' embodiment shown in Fig. 4.

As shown in Fig. 4 through Fig. 6, each of the inner surfaces 21a of the pairs of crimping parts 2V, 21' of the shield terminal 20' that are mutually opposing has an annular protrusion 21b along the outer periphery thereof, which is formed as one with the crimping parts 21% 2V. By means of this annular protrusion 21b, which is formed so as to protrude from the inner surface 21a of each of the crimping parts 2V, it is possible to reliably prevent the outflow of melted low-melting-point substance 23, which was applied to the inner surface 21a of each crimping part 21'when this low-melting- point substance 23 is melted as each crimping part 21' is crimped onto the exposed part of the braid 13. By doing this, it is possible to greatly improve the electrical connection and strength of the connection between the crimped parts 21% 21' of the shield terminal 20 and the braid 13 of the shielded cable 10.

Fig. 7A is a perspective view that shows another embodiment of a shielded cable joining structure according to the present invention, Fig. 7B is a cross-section view along the cutting line Y-Y that is shown in Fig. 7A, Fig. 7C is a perspective view that shows another embodiment of a shield terminal used in this shielded cable joining structure, Fig. 8A is a perspective view that shows the shielded cable to which an embodiment of the joining structure different from above is applied to a shielded cable, Fig. 8B is a perspective view that shows the condition in which the different embodiment of a shield terminal is joined to the shielded cable, and Fig. 8C is a perspective view that shows the condition after the above joining operation is performed.

As shown in Fig. 7C and 8B, the pair of crimping parts 21" and 21" of the shield terminal 20 are approximately U-shaped as viewed from the front and are in mutual offset opposition. As shown in Fig. 8A through 8C, the shield terminal 20" is connected to the shielded cable 10 using the same method as described in the above-noted embodiment. That is, the ultrasonic horn 30 and anvil 31 are used to apply ultrasonic vibration while crimping the pair of crimping parts 21", 21", which are in mutually offset opposition, so that interqally generated heat melts the low-melting-point substance 23 that was applied to the inner surface 21a. The resulting melted low- melting-point substance 23 forms an ultrasonic fused joint between the pair of crimping parts 21 ", 21 " of the shield terminal 20 and the exposed part of the braid 13. In this manner, by usual a pair of crimping parts 21 ", 21 " which is bent so that they are in mutually offset opposition, as shown in Fig. 7A, Fig. 713, and Fig. 8C, it is possible to have the braid 13 at the end A (grounding position) of the shielded cable 10 completely held between the pair of crimping parts 21" 2111 without the occurrence of a space between the ends of the pair of crimping parts 21", 21", thereby reliably preventing damage to and broken connections in a slender braid. As a result, it is possible to achieve a further improvement in the reliability (electrical reliability) of the connection between the shielded cable 10 and the shield terminal 20.

Fig. 9A is a perspective view that shows the condition of an exposed part of the braid 13 at an intermediate position of the shielded cable 10 according to a different embodiment from the above, and Fig. 9B is a perspective view that shows the condition after the different embodiment of shield terminal 20" is joined to the exposed part of the braid 13 at the intermediate position B. 11 As shown in Fig. 9A and Fig. 9B, part of the outer insulation covering 14 at the intermediate position (grounding position) B of the shielded cable 10 is removed so as to expose part of the braid 13, and a fused joint is made as the pair of crimping parts 21", 21" of the shield terminal 20" are crimped. By doing this, it is easy to make a reliable joint between shield terminal 20" and the end A or any grounding position such as the intermediate part B of the shielded cable 10, via the pair of crimping parts 21", 21" of the shield terminal 2011.

While the foregoing embodiments of the present invention were described for the case in which a shield terminal is joined to an end or an intermediate position of a shielded cable using ultrasonic vibration fusion, it is understood that it possible to connect a shield terminal to both an end and an intermediate position of a shielded cable.

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Claims

CLAIMS: 1. Ajoining structure for a shielded cable, comprising: an inner

core wire made of a conductor; an inner insulation covering that covers the inner core wire; 5 a braid that is provided around the outside periphery of the inner insulation covering; an outer insulation covering that covers the braid, said outer insulation partially removed to expose a part of said braid; a shield terminal having a crimping part crimped to said exposed part of said braid; and a low-melting-point joining substance disposed between said exposed part of said braid and said crimping part of said shield terminal; wherein a fused joint between said crimping part of said shield terminal and the exposed part of the braid is formed by applying ultrasonic vibration to said crimping part to melt said low-melting-point joining substance.
2. A method for joining a shielded cable, whereby a shield terminal with a low-melting point substance is joined to a prescribed grounding position of the shielded cable, which is formed by an inner core wire made of a conductor, an inner insulation covering that covers the inner core wire, a braid that is provided around the outside periphery of the inner insulation covering, and an outer insulation covering that covers the braid., said method comprising steps of:

removing part of the outer insulation covering at the grounding position of the shielded cable so as to expose part of the braid; applying a crimping part of the shield terminal to the exposed part of the braid; and 13 using an ultrasonic horn to apply ultrasonic vibration to said crimping part of said shield terminal to which said low-melting-point joining substance has been applied while performing crimping thereof, so as to cause internal generation of heat, which melts said low-melting-point joining substance and forms a fused joint between said shield terminal crimped part and the braid of the shielded cable.
3. A shield terminal which is joined to a prescribed grounding position of a shielded cable which is formed by an inner core wire made of a conductor, an inner insulation covering that covers the inner core wire, a braid that is provided around'the outside periphery of the inner insulation covering, and an outer insulation covering that covers the braid, via a low-melting-point joining substance that is melted by means of ultrasonic vibration, said shield terminal comprising:

a crimping part with a low-melting-point substance, crimped to the braid of the shielded cable; and a connecting part that is connected to a grounded part that is joined to the crimped part.
4. A shield terminal according to claim 3, further comprising an annular protrusion disposed on an outside periphery of an inner surface of said crimping part.
5. A shield terminal according to claim 3, wherein said crimping part is substantially U-shaped and formed so as to be opposing in mutual offset.
6. A shield terminal or jointing structure substantially as hereinbefore described with reference to and as shown in the accompanying drawings.
7. Any novel feature or combination of features disclosed herein.

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