JP6193070B2 - Electrical connection member - Google Patents

Description

  The present invention relates to an electrical connection member, and more particularly, an electrical connection member made of aluminum alloy used for electrical connection by mechanical fastening, wherein the electrical connection member has reduced contact resistance (contact electrical resistance). About.

  Conventionally, copper members have been frequently used as electrical connection members in various devices, for example, bus bars, but in recent years, automobiles, particularly hybrid vehicles and electric vehicles, are made of aluminum alloy for the purpose of improving fuel economy by reducing the weight of the vehicle body. Electrical connection members have been used.

  As such an electrical connection member made of aluminum alloy, nickel (Ni) plating and tin (Sn) plating are applied to the surface of the aluminum alloy material in order to suppress the growth of the surface oxide film having a large electrical resistance value and to reduce the contact resistance. An Al alloy automobile conductor made by sequentially laminating layers is known (see Patent Document 1).

JP 2000-207940 A

  However, in such a conventional Al alloy conductor, since aluminum or aluminum alloy is a difficult plating material, a zinc (Zn) treatment is required as a pretreatment for plating. There was a bug.

That is, with this Zn treatment, the thickness of the aluminum oxide film on the surface can be controlled and reduced, but it is difficult to control the surface shape of aluminum. Therefore, since the Ni plating layer and the Sn plating layer applied thereafter also transfer the surface shape of aluminum, the surface shape of the plating layer cannot be controlled. Therefore, there is a problem that the concentrated resistance cannot be reduced, and eventually the contact resistance cannot be sufficiently reduced.
In addition, performing Zn treatment as a pretreatment for plating not only causes a decrease in manufacturing efficiency due to an increase in the number of processes, but also has a problem of increasing manufacturing costs.

  This invention is made | formed in view of the subject which such a prior art has, The place made into the objective is to provide the member for electrical connection for machine fastening which reduced contact resistance.

  As a result of intensive studies to achieve the above object, the present inventor has found that the above object can be achieved by appropriately controlling the surface shape of the contact surface with the fastened member, and completes the present invention. It came.

That is, the electrical connection member of the present invention is a 6101-T6 aluminum alloy electrical connection member used for electrical connection by mechanical fastening with a copper fastening member.
In this electrical connection member, the arithmetic average roughness Ra and average length RSm on the contact surface with the fastened member are expressed by the following formula (1).
21 ≦ RSm-21 × ln (Ra) ≦ 38 (1)
(Wherein, RSm is RSm <100 μm, and Ra is Ra <10 μm).

According to the present invention, since the surface shape of the contact surface with the member to be fastened is appropriately controlled, it is possible to provide an electrical connection member for machine fastening with reduced contact resistance.
By appropriately controlling the surface shape as described above, the concentrated resistance can be significantly reduced, and the contact resistance can be reduced.

It is a graph which shows the relationship of the measurement result of surface roughness Ra of the example of an invention, and a comparative example, and RSm. It is the schematic which shows the measuring method of contact resistance.

Hereinafter, the member for electrical connection of the present invention will be described.
As described above, the electrical connection member of the present invention is an electrical connection member made of an aluminum alloy used for electrical connection by mechanical fastening with a member to be fastened.
In this electrical connection member, the contact surface with the member to be fastened has a predetermined surface shape defined by equation (1).

  Here, mechanical fastening excludes welding, welding and fusion accompanied by a change in the state of materials constituting various members such as a material to be fastened to be fastened, and adhesion using a fastening agent such as an adhesive. Specifically, bolting, riveting, caulking, and the like can be given.

The member to be fastened is not particularly limited, but examples include various batteries, electric devices such as an inverter and a motor, and other electric connecting members other than the electric connecting member of the present invention, such as a copper bus bar. it can.
In addition, the electrical connection member of the present invention is not particularly limited as long as it is a member that can be used for electrical connection, but typically, it can be used as a bus bar and is preferably used in an automobile.

  The aluminum alloy constituting the electrical connection member of the present invention is not particularly limited, but those having an electrical conductivity of 55 IACS% or more are suitable, for example, JIS standard 6101-T6 material, 1100-H24 material. And so on.

As described above, in the electrical connection member of the present invention, the contact surface with the fastened member has a predetermined surface shape, and the surface shape is expressed by the following formula (1).
21 ≦ RSm-21 × ln (Ra) ≦ 38 (1)
(In the formula, Ra and RSm are defined in JIS B0601, Ra is the arithmetic mean roughness of the cross-sectional curve element, RSm is the average length of the cross-sectional curve element, ln is the natural logarithm, Ra is less than 10 μm, and RSm is 100 μm. Less than).

  In order to implement the surface shape of the above formula (1) on the surface of the aluminum alloy, it can be realized by blasting.

Here, when Ra is 10 μm or more, there is a large variation in the height of the peak of the crest that becomes a contact point at the time of fastening, and the number of contact points and the contact area vary when the contact is formed in order from the highest crest, and the contact resistance value is It becomes unstable. When RSm is 100 μm or more, the number of peaks that become contacts when fastened is reduced, the number of contacts and the contact area are reduced, and the contact resistance value is increased.
In addition, Ra is preferably 3 μm or less, and this provides the advantage that the height of the peak of the mountain that becomes a contact point during fastening is small, the contact point is easily formed efficiently, and the contact resistance is low and stable. It is done.

Only a slight metal protrusion is in contact with the minute interface between the member to be fastened and the electrical connecting member by mechanical fastening. When the surface roughness parameters Ra and RSm are within the range of the formula (1), due to the mutual relationship between Ra and RSm, a part of the crest on the aluminum surface is deformed when fastened to the fastened member and is locally good. The contact resistance can be reduced because a simple contact is formed.
When the formula (1) exceeds 40, Ra is small and the deformation amount of the mountain at the time of fastening is small, or because RSm is large and the contact interval is wide, the contact formation becomes poor and the contact resistance increases. On the other hand, a surface state in which the formula (1) is less than 20 is difficult to produce by blasting, which is not practical for industrial production.

  Such blasting is not particularly limited, but alumina particles having a particle size distribution of F20 to F400 are used as the projection material, and the projection time is 5 to 30 seconds at a pressure of 0.3 to 0.7 MPa. A blasting process can be mentioned.

  In the present invention, by controlling the surface shape of the contact surface with the fastened member so as to satisfy the relationship of the above formula (1), the concentrated resistance when fastened with the fastened member can be reduced. Thereby, contact resistance can be reduced.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to these Examples.

(Examples 1-8)
Test pieces (thickness 3.0 mm, width 25 mm, length 80 mm, bolt hole diameter 6.5 mm) of 6101-T6 aluminum alloy specified in JISH4000 were prepared.
This test piece was subjected to blasting treatment using alumina projection materials F320, F280, F220, F180, F100, F60, F36, and F24 at a jetting pressure of 0.5 MPa and a projection time of 10 seconds. Got.

(Comparative Examples 1 and 2)
The same operation as in the example was repeated except that glass beads F100 and F60 were used instead of alumina as the projecting material, to obtain members for electrical connection of Comparative Examples 1 and 2.

(Comparative Example 3)
This is a material obtained by mirror-polishing the contact surface of a 6101-T6 aluminum alloy test piece.

(Comparative Example 4)
It is a material in which a surface treatment is not performed on a test piece of 6101-T6 aluminum alloy.

<Evaluation of surface shape>
About the electrical connection member of each example, arithmetic mean roughness Ra and average length RSm were measured, and the obtained result was shown in Table 1 and FIG.
As shown in Table 1 and FIG. 1, Examples 1 to 8 of the present invention satisfy 20 <RSm-21 × ln (Ra) <40 , specifically, 21 ≦ RSm-21 × ln (Ra) ≦ 38 . Is pleased.

<Performance evaluation>
As an electrical connection performance evaluation, the contact resistance value of each example of the electrical connection member was measured by a contact resistance measurement method as shown in the schematic diagram of FIG.
Note that a copper material is used as the material to be fastened, and in FIG. 2, the electrical connection member (aluminum alloy test piece) has a thickness of 3.0 mm, a width of 25 mm, a length of 80 mm, and a bolt hole diameter of 6.5 mm. The material (copper test piece) has a thickness of 2.0 mm, a width of 25 mm, a length of 80 mm, and a bolt hole diameter of 6.5 mm. Moreover, the bolt as a fastener has an M6 bolt strength of 6T. The bolt fastening torque was 4 N · m. The measurement was performed by the four-terminal method, and at this time, a value obtained by subtracting the conductor resistance value from the measured resistance value was defined as the contact resistance value.

  As the evaluation result of the contact resistance, less than 200 μΩ was determined to be acceptable (◯), and 200 μΩ or more was determined to be unacceptable (×). As shown in Table 1, in all of the examples of the present invention, the contact resistance was 200 μΩ. In Invention Examples 1 to 5, since Ra was 3 μm or less, the contact resistance was less than 100 μΩ, which was further favorable. In Comparative Examples 1 to 4, the value of the formula (1) was 40 or more and the contact resistance was 200 μΩ or more, which was unacceptable.

As mentioned above, although this invention was demonstrated with some embodiment and an Example, this invention is not limited to these, A various deformation | transformation is possible within the range of the summary of this invention.
For example, the conductor itself may be bent.

  The member for electrical connection of the present invention is useful as a bus bar for carrying out electrical connection with a battery or an electrical device in an automobile, particularly a hybrid car or an electric automobile. It is useful not only for automobiles but also for electrical connection members for other devices and machines.

Claims (2)

A member for electrical connection made of 6101-T6 aluminum alloy used for electrical connection by mechanical fastening with a member to be fastened made of copper ,
Arithmetic average roughness Ra and average length RSm on the contact surface with the above-mentioned fastening member are expressed by the following formula (1).
21 ≦ RSm-21 × ln (Ra) ≦ 38 (1)
An electrical connection member characterized by satisfying a relationship defined by (wherein Ra is less than 10 μm and RSm is less than 100 μm).   The electrical connection member according to claim 1, wherein a surface roughness Ra of the contact surface is 3 μm or less.

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