JPWO2019188168A1 - Communicator and its manufacturing method - Google Patents

Abstract

In the commutator, a metal riser piece is mounted on a resin base, and a segment composed of a metal layer and a carbon layer is joined to the riser piece. The metal layer contains brass and tin and carbon of 0 mass% or more and less than 5 mass%, does not contain copper powder, and the metal layer is soldered to the riser piece without a plating layer on the surface. Segments can be soldered to riser pieces without a plating layer.

Description

The present invention relates to a commutator in which a segment composed of a carbon layer and a metal layer is bonded to a riser piece, and a method for manufacturing the commutator.

Patent Document 1 (JP5901279) describes a commutator in which a segment composed of a carbon layer and a metal layer is joined to a riser piece. The surface layer of the segment is a carbon layer, the bottom layer is a metal layer, and the metal layer has protrusions, which are fitted into the holes of the riser piece.

The inventor considered soldering the segment to the riser piece rather than fitting the protrusions and holes. However, in the segment of Patent Document 1, since the metal layer contains a large amount of graphite (for example, 9.2 mass%), the solder does not get wet on the segment surface, and the segment cannot be directly soldered to the riser piece. Patent Document 2 (JP2001-95207) states that stable conductivity can be ensured by plating the segments with nickel, tin, copper, etc., and forming a metal coating layer such as soldering or brazing. However, when the metal coating layer is formed after plating, pre- and post-treatment and fine adjustment between processes are required, and treatment of the plating waste liquid is also required.

JP5901279 JP2001-95207

An object of the present invention is to solder a segment to a riser piece without a plating layer.

The commutator of the present invention is a commutator in which a plurality of metal riser pieces are mounted on a resin base, and a plurality of segments composed of a metal layer and a carbon layer are joined to the riser pieces on the metal layer side.
The metal layer contains brass and tin and carbon of 0 mass% or more and less than 5 mass%, and does not contain copper powder.
The metal layer is bonded to the riser piece by solder without a plating layer on the surface.

In the method for manufacturing a commutator of the present invention, a ring-shaped segment base body in which a plurality of segments composed of a metal layer and a carbon layer are connected to each other is joined onto a riser piece base body in which a plurality of metal riser pieces are connected to each other. In a commutator manufacturing method in which a resin base for fixing a riser piece is provided, and the riser piece base and the segment base are cut and separated into individual riser pieces and individual segments.
The metal layer contains brass and tin and carbon of 0 mass% or more and less than 5 mass%, and does not contain copper powder.
The feature is that the metal layer of the segment base is soldered to the riser piece without plating the surface of the metal layer. In this specification, the description regarding the commutator also applies to the method for manufacturing the commutator as it is.

The cause of hindering soldering without a plating layer is poor wetting between the metal layer and the solder. The surface of copper is easily oxidized, and an oxide film having low wettability with solder is likely to be formed. Therefore, copper is not included in the metal layer. Further, carbon such as natural graphite, artificial graphite, amorphous carbon, etc. also deteriorates the wettability with the solder. Therefore, the carbon content in the metal layer is set to less than 5 mass%, preferably 2 mass% or less, more preferably 1 mass%. Most preferably, the metal layer does not contain carbon. In this specification, the absence of copper means that the impurity concentration (about 0.1 mass%) is not included, and the absence of carbon means that the impurity concentration (about 0.1 mass%) is not included. Means.

In order to increase the rigidity of the metal layer, a thermoplastic resin such as PPS (polyphenylene sulfide) or PEEK (polyetheretherketone) may be contained in an amount of 2 mass% or less in terms of mass ratio with the entire metal layer. However, since a resin such as a thermoplastic resin deteriorates the wettability between the metal layer and the solder, the metal layer preferably does not contain a resin such as a thermoplastic resin or a thermosetting resin.

Since brass has better wettability with solder than copper, it is used as a skeleton material for a metal layer. Tin melts at a relatively low temperature to sinter the metal layer and improve wettability with solder. It is a preferable condition to realize soldering without plating that tin is contained in an amount of 1 mass% or more in proportion to the total metal components in the metal layer. The wettability with solder improves as the tin content increases. On the other hand, if tin is contained in excess of 25 mass%, tin powder may adhere to the mold during molding of the segment. This requires frequent cleaning of the mold, which reduces the productivity of the commutator. The adhesion of tin powder to the mold becomes more remarkable as the tin content increases. From these facts, the tin content is, for example, 1 mass% or more and 35 mass% or less, more preferably 3 mass% or more and 20 mass% or less, and most preferably 5 mass% or more and 15 mass% or less in terms of the ratio with the total metal components in the metal layer. And. The ratio of the total metal components in the metal layer means the ratio of the metal layer excluding non-metal components such as carbon and thermoplastic resin.

Brass is an alloy of copper and zinc, and when the zinc content in brass is around 20 mass% or more and 30 mass%, the wettability with solder is the best. If the zinc content exceeds 40 mass%, it becomes difficult to precisely mold the metal layer. From these facts, brass preferably contains zinc of 5 mass% or more and 40 mass% or less, copper of 95 mass% or less and 60 mass% or more, and more preferably zinc of 15 mass% or more and 35 mass% or less, and copper of 85 mass% or less and 65 mass% or more. It contains, most preferably zinc 15 mass% or more and 32 mass% or less, and copper 85 mass% or less and 68 mass% or more.

Preferably, the metal layer contains brass, tin and silver as metal components, and the silver content is 0.2 mass% or more and 10 mass% or less, more preferably 0.5 mass% or more and 9 masses in proportion to the total metal components in the metal layer. % Or less, most preferably 1 mass% or more and 9 mass% or less. Silver significantly improves the wettability between the metal layer and the solder, and further reduces the resistivity of the metal layer. However, since silver is an expensive metal, its content should be 10 mass% or less. Since the wettability improves with the silver content, the silver content is preferably 0.2 mass% or more, more preferably 0.5 mass% or more, and most preferably 1 mass% or more. Preferably, the silver content is 9 mass% or less. Even when silver is contained, the tin content in the total of brass and tin is, for example, 1 mass% or more and 35 mass% or less, preferably 3 mass% or more and 20 mass% or less, and most preferably 5 mass% or more and 15 mass% or less. ..

Preferably, the riser piece is provided with a hole for accommodating the solder. During the manufacture of the commutator, solder is injected through this hole between the metal layer of the segment base and the riser single base. The wettability between the metal layer and the solder is not always high. Therefore, if the above holes are not provided, for example, when solder paste is placed on the riser single base and the segment is lowered and soldered, the solder does not spread uniformly between the metal layer and the riser single base, and the solder spreads on the riser single base. May escape to the outside of the. On the other hand, when a hole is provided in the riser single body and a solder paste or the like is injected into the hole, excess solder does not leak from between the metal layer and the riser single body to the outside of the riser single body. Excess solder stays in the holes and an appropriate amount of solder spreads between the metal layer and the riser slab.

The components of the metal layer are most preferably three components of brass, tin and silver, and then preferably two components of brass and tin. However, in addition to these, the metal layer may contain less than 5 mass% of carbon, less than 2 mass% of thermoplastic resin, other metals mixed as impurities, and the like.

Top view of the commutator of the embodiment Sectional view of the commutator of the embodiment along the 11-11 directions of FIG. Sectional drawing which shows the joining of a riser piece and a segment in an Example.

The optimum examples for carrying out the present invention are shown below. The present invention is not limited to the examples, but can be modified based on the claims and by adding matters known to those skilled in the art to the examples.

1 to 3 show the structure of the commutator 2 of the embodiment. Reference numeral 4 denotes a resin base made of a thermosetting resin or the like, which supports a plurality of riser pieces 6, and each of the riser pieces 6 is bonded to a segment 8 by a solder layer 14. The riser piece 6 is made of metal, the hook 9 protrudes, and a wiring (not shown) is wound around the hook 9. Further, the commutator 2 is provided with a slit 15 to separate the riser pieces 6 from each other and the segments 8 from each other.

The segment 8 is composed of two layers, a carbon layer 10 on the surface layer and a metal layer 12 which is a lower layer and is joined to the riser piece 6. Then, as described above, the metal layer 12 is joined to the riser piece 6 by the solder layer 14. The component of the solder layer 14 is tin solder containing tin as a main component, but the component is arbitrary.

As shown in FIG. 3, the riser piece 6 preferably has a hole 16 facing the metal layer 12, and excess solder that has not spread between the riser piece 6 and the segment 8 remains in the hole 16 as a solder pool 18. There is. The hole 16 may not be provided.

A commutator was prototyped using the following materials. The unit of content is mass%.
Brass powder: with an average particle size of 40 μm and a zinc content of 20 mass%, and with an average particle size of 38 μm and a zinc content of 30 mass%, etc.
Tin powder: Average particle size 20 μm
Silver powder: Average particle size 20 μm
Copper powder: Electrolytic copper powder with an average particle size of 35 μm

Carbon: Natural graphite with an average particle size of 25 μm
Thermoplastic resin: PPS (polyphenylene sulfide) with an average particle size of 15 μm

Solder: Tin solder
Riser piece: Copper

A metal layer material (Table 1) composed of brass powder and tin powder or brass powder and tin powder and silver powder was uniformly mixed with a mixer and charged into a mold. The carbon layer material composed of carbon and the thermoplastic resin was uniformly mixed with a mixer, put into a mold, and laminated on the metal layer material. The metal layer material and the carbon layer material were press-molded, for example, heated and fired at 300 ° C. in air, and a ring-shaped two-layer segment base was produced by melting tin and melting a thermoplastic resin.

In addition to the materials shown in Table 1, the metal layer materials used were those shown in Table 2, and those having a zinc content of 10 mass% and 36 mass% in brass. In addition, a segment base material in which a thermoplastic resin was mixed with a metal layer material was prototyped. The thermoplastic resin increases the rigidity of the metal layer, but is not preferable because it reduces the wettability with the solder. The allowable range is 2 mass% or less with respect to the total amount of the metal layer, and the content of the thermoplastic resin is 0 mass% or more and 1.0 mass. % Or less is preferable, and it is most preferable not to contain a thermoplastic resin. Hereinafter, the metal layer containing no thermoplastic resin will be described. As the zinc content in brass increased, the wettability with the solder improved, but even if it exceeded 30 mass%, the wettability with the solder did not improve any more. When the zinc content was 36 mass%, the metal layer could not be densely sintered. Based on these facts, the samples shown in Tables 1 and 2 were prototyped using brass with zinc contents of 20 mass% and 30 mass%.

The carbon layer consists of natural graphite with an average particle size of 25 μm or more of 85 mass% or more and PPS of 15 mass% or less, and a thermoplastic resin such as PPS supports the strength of the carbon layer and the bonding between the carbon layer and the metal layer. .. The thermoplastic resin is not limited to PPS but may be PEEK or the like, and the melting point is preferably 230 ° C. or higher. The content of the thermoplastic resin is preferably 3 mass% or more and 15 mass% or less in terms of mass ratio with the carbon layer, and particularly preferably 5 mass% or more and 15 mass% or less.

A riser piece base body in which a plurality of riser pieces were integrated and a segment base body were overlapped and soldered with tin solder. The holes in the riser pieces in Tables 1 and 2 mean the holes 16 in FIG. 3, and when there are holes, the riser piece base was turned up, solder paste was injected through the holes 16, and the solder paste was heated in a furnace and soldered. In the case of no holes, the solder paste was applied to the riser piece base, the segment bases were overlapped from above, the pressure was applied to the extent that the solder spreads between the riser piece and the segment, and the solder was heated in a furnace and soldered.

A resin base of a thermosetting resin was molded around the riser piece base and the segment base after soldering, and the base was cut and separated into individual riser pieces and segments. In addition, the exposed part of the riser piece was tin-plated. The base body may be cut after molding the resin base or before molding.

The electrical resistivity of the metal layer was measured as follows. The metal layer materials of each sample in Tables 1 and 2 were uniformly mixed, press-molded, and heat-treated in air at 300 ° C. to prepare test pieces for measuring electrical resistance. Next, a direct current was applied in the length direction of the test piece, the voltage drop between the specified lengths was measured, and the electrical resistivity was calculated.

The solder wettability between the riser piece and the metal layer was evaluated as follows.
⊚: The molten solder can be wetted and spread over the entire metal layer for joining.
◯: There are cavities (voids) in a part of the molten solder, but there is no problem in joining.
Δ: There are many cavities (voids) in the molten solder, and there is some variation in the bonding.
X: The molten solder does not get wet with the metal layer and cannot be joined.

When the metal layer contains a large amount of tin, tin powder may adhere to the inside of the mold and hinder the subsequent molding. Therefore, the degree of adhesion of tin to the mold was evaluated and evaluated as follows.
⊚: No adhesion to the mold during molding.
◯: Regular mold cleaning is required.
Δ: The frequency of mold cleaning increases.
X: Molded product adheres to the mold and cannot be separated (molding is not possible).

From the samples 33 and 34 in Table 2, it was found that the wettability with the solder was lowered when the metal layer contained copper. Further, from the samples 35 and 36 in Table 2, it was found that the carbon in the metal layer reduces the wettability with the solder.

When the tin content in the metal layer was 37 mass%, tin powder adhered to the mold during molding, causing trouble (samples 29, 30). When tin was 0.5 mass%, the electrical resistance was high. 0.4mass% silver has a small effect (comparison between samples 23 and 24 and samples 1 and 2), but when the silver content is 3mass% to 9mass%, the wettability with solder is significantly improved (for example, samples 13 and 14). Comparison of samples 2 and 3). In addition, when holes were provided in the riser piece, the wettability with the solder was significantly improved (for example, comparison between Samples 2,4,6,8 and Samples 1,3,5,7).

2 Communicator 4 Resin base 6 Riser piece 8 Segment 9 Hook 10 Carbon layer 12 Metal layer 14 Solder layer 15 Slit 16 holes 18 Solder pool

Claims (7)

A commutator in which a plurality of metal riser pieces are mounted on a resin base, and a plurality of segments composed of a metal layer and a carbon layer are joined to the riser pieces on the metal layer side.
The metal layer contains brass and tin and carbon of 0 mass% or more and less than 5 mass%, and does not contain copper powder.
A commutator in which the metal layer is bonded to the riser piece by solder without a plating layer on the surface. The commutator according to claim 1, wherein the metal layer contains brass and tin and does not contain carbon. The brass is an alloy of zinc 5 mass% or more and 40 mass% or less, and copper 95 mass% or less and 60 mass% or more.
The commutator according to claim 1 or 2, wherein the brass is contained in an amount of 80 mass% or more and 99 mass% or less, and tin is contained in an amount of 20 mass% or less and 1 mass% or more as a ratio to the total metal components in the metal layer. The commutator according to any one of claims 1 to 3, wherein the brass is an alloy of zinc 15 mass% or more and 35 mass% or less and copper 85 mass% or less and 65 mass% or more. Claim 1 is characterized in that the metal layer contains brass, tin and silver as metal components, and the silver content is 0.2 mass% or more and 10 mass% or less in proportion to all metal components in the metal layer. Any of the commutators from ~ 4. The commutator according to any one of claims 1 to 5, wherein the riser piece has a hole for accommodating solder. A ring-shaped segment base body in which a plurality of segments composed of a metal layer and a carbon layer are connected to each other is joined onto a riser piece base body in which a plurality of metal riser pieces are connected to each other, and then a resin base for fixing the riser pieces is provided. At the same time, in a method for manufacturing a commutator, which cuts a riser piece and a segment body and separates them into individual riser pieces and individual segments.
The metal layer contains brass and tin and carbon of 0 mass% or more and less than 5 mass%, and does not contain copper powder.
A method for manufacturing a commutator, which comprises soldering a metal layer of a segment base to the riser piece without plating the surface of the metal layer.

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