Double-layered disc, and commutator comprising same, and manufacturing method of commutator

Abstract

To achieve a double-layer disc in which a metal layer is excellent in strength and small in electric resistivity and which can be soldered to a raised piece without plating, a double-layer disc (10) has a carbon layer (1) and a metal layer (2) which can be soldered to a raised piece (20) without plating on a surface (2a) and which contains copper powder, the content of the copper powder being 10 mass% or more when the metal component in the metal layer 2 is taken as 100 mass%.

Description

Technical Field

[0001] The present invention relates to a double-layer disk, a commutator including the disk, and a method for manufacturing the commutator. Background Technology

[0002] Previously, commutators with risers attached to a disk were known. When manufacturing such a commutator, it is necessary to attach the disk to the riser. Previous methods of attaching the disk to the riser include, for example, the techniques disclosed in Patent Documents 1 to 4.

[0003] In the technology disclosed in Patent Document 1, a plating layer is formed on the disk, and the disk and the riser are soldered together via the plating layer.

[0004] In the technology disclosed in Patent Document 2, a protrusion is provided on a double-layered disk having a metal layer and a carbon layer, and a hole is provided on a riser plate. Then, the double-layered disk and the riser plate are joined by pressing the protrusion of the double-layered disk into the hole of the riser plate.

[0005] In the technology disclosed in Patent Document 3, a protrusion is provided on a single-layer disk having a carbon layer, and a hole is provided on a riser plate. Furthermore, a plating layer is applied to both the single-layer disk and the riser plate. Then, the protrusion of the double-layer disk is gently pressed into the hole of the riser plate, and the single-layer disk and the riser plate are simultaneously soldered together.

[0006] Patent Document 4 discloses a method for bonding a riser to the metal layer side of a double-layered disk having a metal layer and a carbon layer. Furthermore, in this method, the metal layer is soldered to the riser without any plating on its surface. To perform solder bonding to the riser without plating as described above, the metal layer in the double-layered disk has a structure comprising brass, tin, and 0 mass% to less than 5 mass% carbon, and does not contain copper powder.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Publication No. 2003-502809

[0010] Patent Document 2: Japanese Patent Application Publication No. 2002-64958

[0011] Patent Document 3: Japanese Patent Application Publication No. 10-4653

[0012] Patent Document 4: International Publication No. 2019 / 188168 Summary of the Invention

[0013] The problem that the invention aims to solve

[0014] However, the prior art as described above has the following problems.

[0015] In the technology disclosed in Patent Document 1, a plating process is required to plate the disk before it can be joined with the riser plate. Therefore, the joining of the disk and riser plate becomes complicated and cannot be performed easily.

[0016] In the technologies disclosed in Patent Documents 2 and 3, the protrusions and holes need to be fitted together in order to press the disk and the lifting plate into place, which leads to the problem of complicated shapes of the disk and the lifting plate.

[0017] The technology disclosed in Patent Document 4 is simple because it does not require a plating process for the disk. However, the resistivity and strength of the metal layer of the double-layer disk are insufficient.

[0018] One aspect of the present invention aims to realize a double-layer disk that can be soldered to a riser without plating, has excellent metal layer strength and low resistivity, a commutator including the disk, and a method for manufacturing the commutator.

[0019] Technical means to solve the problem

[0020] To address the aforementioned issues, one aspect of the present invention includes the following.

[0021] A double-layer disk has a carbon layer and a metal layer. In the double-layer disk, the metal layer can be soldered to a riser plate without a surface plating. The metal layer contains copper powder, and when the metal composition in the metal layer is set to 100% by mass, the content of the copper powder is 10% by mass or more.

[0022] A double-layer disk has a carbon layer and a metal layer. In the double-layer disk, the metal layer, without any surface plating, can be soldered to a riser plate. The metal layer contains copper powder. When the content (mass%) of the copper powder in the metal layer is set to 100% by mass, and the average particle size (μm) of the copper powder is set to b, the following conditions are met:

[0023] a / b≧0.34.

[0024] A method for manufacturing a commutator includes: a coating step of applying solder to the surface of the metal layer in a double-layer disk having a carbon layer and a metal layer without forming a plating layer; and a bonding step of stacking the solder-coated metal layer with a riser plate matrix and then heating it to bond the metal layer to the riser plate matrix, wherein the metal layer contains copper powder, and when the metal composition in the metal layer of the double-layer disk is set to 100% by mass, the content of the copper powder is 10% by mass or more.

[0025] A method for manufacturing a commutator includes: a coating step, in which solder is applied to the surface of the metal layer in a double-layer disk having a carbon layer and a metal layer without forming a plating layer; and a bonding step, in which the solder-coated metal layer is stacked with a riser plate matrix and then heated to bond the metal layer to the riser plate matrix, wherein the metal layer contains copper powder, and when the content (mass%) of copper powder is set as a, where the metal composition in the metal layer is 100% by mass, and the average particle size (μm) of the copper powder is set as b, the following conditions are met:

[0026] a / b≧0.34.

[0027] The effects of the invention

[0028] According to one aspect of the present invention, a double-layer disk capable of solder bonding with a riser without plating, having a metal layer with excellent strength and low resistivity, a commutator including the disk, and a method for manufacturing the commutator can be realized. Attached Figure Description

[0029] [ Figure 1 [This is a plan view showing the schematic structure of the commutator of Embodiment 1 and Embodiment 2 of the present invention.]

[0030] [ Figure 2 ]yes Figure 1 A cross-sectional view of the commutator along line II-II.

[0031] [ Figure 3 ] is to show Figure 2 Enlarged cross-sectional view of the joint between the middle double-layer disk and the riser plate.

[0032] [ Figure 4 [Illustration 1] is a cross-sectional view showing a schematic structure of a double-layered disk according to an embodiment of the present invention.

[0033] [ Figure 5 [This is a graph showing the relationship between the copper powder content / average particle size of the copper powder and the solder wettability in relation to Examples 1 to 7, Comparative Examples 2 and 5.] Detailed Implementation

[0034] [Implementation Form 1]

[0035] The embodiments of the present invention will now be described in detail. However, the present invention is not limited thereto, and various modifications can be made within the scope described. Embodiments obtained by suitable combinations of the technical methods disclosed in different embodiments and examples are also included within the technical scope of the present invention. Furthermore, in this specification, unless otherwise specified, "A to B" representing a numerical range means "A or more (including A and greater than A) and B or less (including B and less than B)".

[0036] (Commutator structure)

[0037] Figure 1 This is a plan view showing the schematic structure of the commutator 100 according to this embodiment. Additionally, Figure 2 yes Figure 1 A cross-sectional view of commutator 100 along line II-II. Figure 3 It is shown Figure 2 Enlarged cross-sectional view of the joint between the middle double-layer disk 10 and the lifting plate 20.

[0038] like Figure 1 and Figure 2 As shown, the commutator 100 of this embodiment has a generally disc-shaped appearance and a through hole 31 extending along the X-axis in the generally disc-shaped manner. Here, in this application, the X-axis direction of the commutator 100 is defined as the HD direction (height direction), "HDa" refers to one side of the HD direction, i.e., the upper side, and "HDb" refers to the other side of the HD direction, i.e., the lower side. Furthermore, "circumferential direction" refers to... Figure 1 From a top view, this refers to the circumferential direction of the approximate disk shape that constitutes the external shape of the commutator 100. Furthermore, the term "radial direction" refers to the radial direction of the approximate disk shape that constitutes the external shape of the commutator 100.

[0039] The commutator 100 includes a double-layer disk 10, a solder layer 3, a riser 20, and a resin base 30. Furthermore, as... Figure 2 As shown, in the commutator 100, from the HDa side to the HDb side, the components are arranged in the following order: double-layer disk 10, solder layer 3, riser 20, and resin base 30 (lower part 30a).

[0040] The resin base 30 comprises a thermosetting resin and has a thick-walled, generally disc-shaped lower portion 30a and two side portions 30b. The two side portions 30b are respectively erected on the HDa side relative to the lower portion 30a and extend circumferentially. In the external shape of the commutator 100, the two side portions 30b of the resin base 30 respectively form the outer peripheral surface of the generally disc-shaped structure and the through hole 31. Furthermore, a plurality of commutator segments 40 are formed on the HDa side surface of the lower portion 30a of the resin base 30. Figure 1 As shown, the commutator segments 40 are formed in a generally fan-shaped form when viewed from above. Furthermore, multiple commutator segments 40 are arranged radially from the through-hole 31 on the HDa side of the lower portion 30a, with equal spacing between them in the circumferential direction. Moreover, in the radial direction, the circumferential surface of the commutator segments 40 is covered by two side portions 30b.

[0041] The riser 20 is a conductive component electrically connected to each commutator segment 40. Multiple risers 20 are supported on the HDa side of the lower portion 30a of the resin base 30 and have a body 21 and a hook 22. The body 21 and the hook 22 are connected to each other. The body 21 is the portion that engages with the commutator segment 40 through the solder layer 3. The hook 22 protrudes from the side portion 30b on the outer periphery of the resin base 30. The hook 22 is provided for electrical connection to an external circuit, and wiring (not shown) is wound around the hook 22.

[0042] The commutator segment 40 comprises a double-layer disk 10. The riser segment 20 (segment body 21) is bonded to the metal layer 2 side of the double-layer disk 10. Furthermore, the metal layer 2 is solder-bonded to the riser segment 20 without any plating on its surface. That is, the metal layer 2 is bonded to the riser segment 20 (segment body 21) on the HDb side via a solder layer 3. No plating is present between the metal layer 2 and the solder layer 3.

[0043] The composition of solder layer 3 is not particularly limited as long as it is a material used in existing known solder joints. The composition of solder layer 3 is preferably tin solder with tin as the main component.

[0044] Additionally, the commutator 100 includes a slit 32 that electrically insulates adjacent commutator segments 40. The slit 32 extends at least from the carbon layer 1 to the segment body 21 along the HD direction. The slit 32 separates the commutator segments 40 from each other while simultaneously separating the riser segments 20 from each other.

[0045] (Structure of a double-layered disc)

[0046] As described above, previously, as in Patent Document 4, a technique was proposed whereby, when a riser is joined to the metal layer side of a double-layer disk having a metal layer and a carbon layer, the metal layer and the riser are soldered together without any plating on the surface of the metal layer. Furthermore, in order to solder-joint the riser with no plating as described above, the metal layer in the double-layer disk has a structure containing brass, tin, and 0 mass% to less than 5 mass% carbon, and does not contain copper powder (hereinafter, sometimes simply referred to as a conventional structure).

[0047] However, the inventors of this application independently discovered the following problem: even when using a double-layer disk with an existing metal layer structure to manufacture the commutator, as in Patent Document 4, the characteristics of the metal layer in terms of strength, solder wettability, and resistivity are still insufficient. Therefore, the inventors of this application have conducted in-depth development with the goal of developing a double-layer disk that, when used in a commutator, can be soldered to the riser plate without plating, and has excellent metal layer strength and low resistivity.

[0048] As a result, by setting the copper powder content in the metal layer to a specific amount or more, a double-layer disk with improved strength, solder wettability, and resistivity of the metal layer was successfully developed. Specifically, the inventors of this application discovered the following novel insight: when the metal composition in the metal layer is set to 100% by mass, the aforementioned problem can be solved by setting the copper powder content to 10% by mass or more, thereby completing the double-layer disk 10 of this embodiment.

[0049] In prior art, such as Patent Document 4, copper powder is not required in the metal layer of the double-layer disk. Therefore, the double-layer disk 10 of this embodiment, based on the novel insight described above, could not have been predicted according to prior art, but was independently developed by the inventors of this application.

[0050] In addition, in order to solve the aforementioned problem, the inventors of this application conducted further in-depth research and discovered the following insights: by setting the average particle size of copper powder to below 30 μm, the strength of the metal layer, solder wettability, and all characteristics of resistivity are further improved.

[0051] The double-layered disk 10 of this embodiment will be described in further detail below. Figure 4 This is a cross-sectional view showing the schematic structure of the double-layered disk 10 in this embodiment. Figure 4 As shown, the double-layer disk 10 of this embodiment has a carbon layer 1 and a metal layer 2. The double-layer disk 10 has a structure in which the carbon layer 1 is stacked on the HDa side of the metal layer 2. Moreover, the metal layer 2 can be soldered to the riser 20 without a plating layer on the surface 2a. In other words, the metal layer 2 has a solder layer 3 forming area on the surface 2a, but on the other hand, it does not have a plating layer forming area.

[0052] (Carbon layer 1)

[0053] In the double-layer disk 10 of this embodiment, the carbon layer 1 can be any carbon layer used in existing commutators. Preferably, the carbon layer 1 comprises carbon material and thermoplastic resin.

[0054] Carbon material is the main component of carbon layer 1, and examples include natural graphite, artificial graphite, and amorphous carbon. Among these, natural graphite is preferred. Furthermore, the content of carbon material is only required to enable carbon layer 1 to function in commutator 100. The content of carbon material relative to carbon layer 1 is preferably 80% by mass or more, more preferably 85% by mass or more. Additionally, the average particle size of the carbon material is preferably 5 μm to 70 μm, more preferably 15 μm to 40 μm.

[0055] Furthermore, the thermoplastic resin serves to maintain the strength of the carbon layer 1 and the bonding between the carbon layer 1 and the metal layer 2. The thermoplastic resin is not particularly limited as long as it can perform the aforementioned functions; examples include polyphenylene sulfide (PPS) and polyetheretherketone (PEEK), among which polyphenylene sulfide (PPS) is preferred. Additionally, the melting point of the thermoplastic resin is preferably 230°C or higher.

[0056] Furthermore, the content of the thermoplastic resin can be appropriately set to achieve the aforementioned function. The content of the thermoplastic resin relative to the carbon layer 1 is preferably 3% to 15% by mass, more preferably 5% to 15% by mass.

[0057] (Metal layer 2)

[0058] In the double-layer disk 10 of this embodiment, the metal layer 2 can be soldered to the riser without a surface plating. The metal layer 2 contains copper powder. Moreover, when the metal composition in the metal layer 2 is set to 100% by mass, the copper powder content is 10% by mass or more, preferably 12% by mass or more, more preferably 13% by mass or more, and most preferably 13.5% by mass or more.

[0059] By using copper powder within the specified range, a double-layer disk 10 with excellent strength and low resistivity can be achieved when used in a commutator, enabling solder bonding with the riser plate 20 without plating. Specifically, the metal layer 2 of the double-layer disk 10 exhibits the following effects: (a) improved solder wettability, (b) reduced resistivity of the metal layer 2, and (c) increased strength of the metal layer 2.

[0060] Furthermore, in this application specification, the content of copper powder does not refer to the content of copper content relative to the total metallic composition of metal layer 2; the content of copper powder does not include the copper content contained in brass. In other words, the content of copper powder can be said to be the content of copper content derived from copper powder relative to the total metallic composition of metal layer 2. Additionally, the term "metallic composition of metal layer 2" refers to the composition after removing non-metallic components from metal layer 2.

[0061] Furthermore, there is a tendency that the higher the copper powder content, the better the effect of (a) to (c). Therefore, there is no particular upper limit to the copper powder content. However, when the double-layer disk 10 of this embodiment is used in a fuel pump commutator for automobiles, etc., and when it is used in applications involving contact with fuel containing sulfur as an impurity, in order to suppress corrosion of the double-layer disk 10 caused by sulfur, the copper powder content is preferably 90% by mass or less, more preferably 70% by mass or less, and particularly preferably 60% by mass or less.

[0062] Furthermore, the effects described in (a) to (c) can be improved by setting the average particle size of the copper powder. In the double-layer disk 10 of this embodiment, the average particle size of the copper powder is not particularly limited as long as the effects described in (a) to (c) are achieved, but it is preferably 30 μm or less, more preferably 25 μm or less. By using the average particle size of the copper powder within the aforementioned range, the effects described in (a) to (c) are further improved. In addition, there is a tendency that the smaller the particle size of the copper powder, the better the effects described in (a) to (c).

[0063] On the other hand, the average particle size of the copper powder is preferably 15 μm or more. Therefore, in the double-layer disk 10 of this embodiment, the average particle size of the copper powder is preferably 15 μm to 30 μm, and more preferably 15 μm to 25 μm.

[0064] Furthermore, in the double-layer disk 10 of this embodiment, the metal layer 2 preferably contains brass powder. The brass powder is an alloy of copper and zinc. The brass powder makes the metal layer 2 a layer with excellent filling properties and corrosion resistance. On the other hand, compared to copper powder, brass powder worsens the solder wettability and strength of the metal layer 2. Therefore, in order to enable solder bonding with the riser 20 without plating and to ensure the strength of the metal layer 2, when the metal composition of the metal layer 2 is set to 100% by mass, the content of brass powder is preferably 80% by mass or less. Furthermore, there is no particular limitation on the lower limit of the brass content.

[0065] Furthermore, when the metal content in the brass powder is set to 100% by mass, the zinc content in the brass powder is preferably 20% to 40% by mass, more preferably 20% to 30% by mass. The corrosion resistance is achieved by using the zinc content within the aforementioned range.

[0066] Furthermore, in the double-layer disk 10 of this embodiment, the metal layer 2 preferably contains brass powder, copper powder, and tin. Tin melts at a relatively low temperature. Therefore, by including tin in the metal layer 2, the metal layer 2 can be sintered at a low temperature, while the solder wettability of the metal layer 2 can be improved.

[0067] A tin content of 5% by mass or more is a preferred condition for achieving solder bonding with the riser plate 20 without plating. Furthermore, a higher tin content tends to improve solder wettability. On the other hand, if the tin content exceeds 15% by mass, the double-layer disk 10 may deform during sintering. Therefore, in the double-layer disk 10 of this embodiment, when the metal composition of the metal layer 2 is set to 100% by mass, the tin content is preferably 5% to 15% by mass, more preferably 5% to 10% by mass.

[0068] Furthermore, the contents of copper powder, brass powder, and tin contained in metal layer 2, with the metal composition set at 100% by mass, can be calculated using existing known measurement methods. The contents of each of the copper powder, brass powder, and tin can be calculated, for example, by X-ray determination, X-ray fluorescence analysis (XRF), or analysis using three-dimensional scanning electron microscopy-energy-dispersive X-ray spectroscopy (3D-SEM-EDX).

[0069] Furthermore, carbon materials such as natural graphite, artificial graphite, and amorphous carbon can worsen the wettability of solder. Therefore, in the double-layer disk 10 of this embodiment, the metal layer 2 is preferably carbon-free. Here, "carbon-free" means not containing more than 0.1% by mass of carbon.

[0070] In addition, the metal layer 2 may also contain thermoplastic resin as another component. Thermoplastic resin improves the rigidity of the metal layer 2. Considering this rigidity, the content of the thermoplastic resin is 2% by mass or less. On the other hand, thermoplastic resin tends to worsen the solder wettability of the metal layer 2. Therefore, considering solder wettability, the metal layer 2 preferably does not contain thermoplastic resin. Therefore, considering these factors, when the metal layer 2 as a whole is set to 100% by mass, the content of thermoplastic resin in the metal layer 2 is preferably 2% by mass or less, preferably 0% to 1% by mass, and more preferably 0% by mass, i.e., it does not contain thermoplastic resin. Examples of thermoplastic resins used for the metal layer 2 include polyphenylene sulfide (PPS) and polyetheretherketone (PEEK), among which polyphenylene sulfide (PPS) is preferred.

[0071] Furthermore, the double-layer disk 10 of this embodiment can be manufactured by the following method. First, a metal material (copper powder, brass powder, etc.) containing the metal components constituting the metal layer 2 and a non-metallic component such as a thermoplastic resin, as needed, is uniformly mixed in a mixer and then placed into a mold. Next, a carbon layer material containing carbon material and thermoplastic resin is uniformly mixed in a mixer and then placed into the mold to be layered onto the metal layer material. Then, the metal layer material and carbon layer material in the mold are pressed and formed, for example, by heating and calcining at 320°C in a reducing gas environment, thereby manufacturing the double-layer disk 10. (Manufacturing...) Figure 1 and Figure 2 In the case of the double-layer disk 10 provided in the commutator 100 shown, the double-layer disk 10 becomes an annular commutator segment matrix.

[0072] Furthermore, in the double-layer disk 10 of this embodiment, in addition to achieving the effects described in (a) to (c), the metal layer 2 is preferably to have all of the following characteristics (a') to (c').

[0073] Characteristic (a') is that the solder wettability of the metal layer 2 is preferably 1.9 mm or less, more preferably 1.8 mm or less, and even more preferably 1.6 mm or less. Furthermore, the solder wettability can be determined by the following method: A paste solder is applied to a test piece of the metal layer 2 in an amount of 0.09 g to a height of 3 mm. Then, the test piece coated with the paste solder is heated at an actual temperature of 300°C for 2 minutes using a heating plate, and the height of the melted paste solder is measured. This measured value is taken as the solder wettability. In this measurement method, if the height of the melted paste solder is small, the solder wettability is good.

[0074] Characteristic (b') is that the resistivity of the metal layer 2 is preferably 2.1 μΩ·m or less, more preferably 1.9 μΩ·m or less, and even more preferably 1.5 μΩ·m or less. Furthermore, the resistivity can be measured by the voltage drop method according to Japanese Industrial Standards (JIS) C 2820.

[0075] Characteristic (c') is that the bending strength of the metal layer 2 is preferably 8 MPa or more, more preferably 10 MPa or more. Furthermore, the bending strength can be measured according to JIS C 2820.

[0076] (Manufacturing method of commutator 100)

[0077] The following is for reference Figures 1-3 The manufacturing method of the commutator 100 according to this embodiment will be described. The manufacturing method of the commutator 100 according to this embodiment includes a coating process and a bonding process. In the coating process, solder is applied to the surface of the metal layer 2 in the double-layer disk 10 having a carbon layer 1 and a metal layer 2 without forming a plating layer. Through the coating process, a solder layer 3 is formed on the surface of the metal layer 2. In the bonding process, the solder-coated metal layer 2 is stacked with the base of the riser plate 20 and then heated to bond the metal layer 2 to the base of the riser plate 20.

[0078] Furthermore, in the manufacturing method of the commutator 100 in this embodiment, the metal layer 2 contains copper powder. Moreover, when the metal composition in the metal layer 2 of the double-layer disk 10 is set to 100% by mass, the copper powder content is 10% by mass or more. Therefore, a commutator 100 comprising a double-layer disk 10 with excellent strength and low resistivity, capable of solder bonding to riser plates without plating, can be manufactured.

[0079] The double-layer disk 10 used in the coating process is as follows: Figure 1 and Figure 2 The commutator segment housing is shown as an annular structure formed by connecting multiple commutator segments 40 together. This type of commutator segment housing can be manufactured by appropriately setting the shape of the mold used in manufacturing the double-layer disk 10.

[0080] In addition, the base material of the lifting plate 20 used in the bonding process is as follows: Figure 1 and Figure 2 The configuration shown involves connecting multiple riser plates 20 to each other. The base of such riser plates 20 can be manufactured using existing known methods.

[0081] The preferred method for manufacturing the commutator 100 in this embodiment includes a base forming process and a separation process after the joining process.

[0082] In the base forming process, a resin base 30 is provided in the solder joint between the commutator segment mother body (double-layer disk 10) and the riser segment mother body after the joining process to support the riser segment 20 mother body. Specifically, a resin base 30 having a lower part 30a and two side parts 30b is formed around the solder joint between the commutator segment mother body and the riser segment mother body.

[0083] In addition, during the separation process, the commutator segment body and the riser segment 20 body are cut to separate them into individual riser segments 20 and individual commutator segments 40. The separation process forms the slit 32. Furthermore, the separation process is performed after the base forming process.

[0084] The manufacturing method of the commutator 100 in this embodiment may also include a riser plate plating process. In the riser plate plating process, the riser plate 20, i.e., the hook 22, exposed from the resin base 30, is tin-plated.

[0085] Furthermore, in the manufacturing method of the commutator 100 of this embodiment, the coating process, the bonding process, the base forming process, the separation process, and the riser plating process can each adopt known methods in existing commutator manufacturing methods.

[0086] [Implementation Form 2]

[0087] Regarding another embodiment of the present invention, if based on Figures 1-3 The following description will be provided. The double-layer disk 10 of this embodiment is characterized by the ratio of the copper powder content (mass%) to the average particle size (μm) of the copper powder when the metal composition in the metal layer 2 is set to 100% by mass. In the double-layer disk 10 of this embodiment, the structure other than the aforementioned feature is the same as that of the double-layer disk of Embodiment 1.

[0088] The inventors of this application have conducted in-depth development with the goal of developing a double-layer disk that, in addition to the characteristics related to the copper powder content in Embodiment 1, can be soldered to the riser plate without plating when used in a commutator, and has excellent metal layer strength and low resistivity.

[0089] Furthermore, firstly, regarding the effect described in (a), the inventors of this application believe that the solder wettability of the metal layer 2 is related to the "total surface area of ​​copper powder contained in 100 g of the metal composition of the metal layer". Specifically, it is speculated that the higher the "total surface area of ​​copper powder contained in 100 g of the metal composition of the metal layer", the better the solder wettability, i.e., it possesses the aforementioned characteristic (a'). The "total surface area of ​​copper powder contained in 100 g of the metal composition of the metal layer" is related to the ratio of the copper powder content (mass%) to the average particle size (μm) of the copper powder when the metal composition in the metal layer is set to 100% by mass. Therefore, based on the aforementioned speculation, the inventors of this application focused on the ratio of the copper powder content (mass%) to the average particle size (μm) of the copper powder when the metal composition in the metal layer is set to 100% by mass, and conducted an in-depth study on the correlation between this ratio and the aforementioned characteristic (a'). As a result, the inventors of this application successfully developed a double-layer disk that exhibits the effect described in (a) by setting the ratio of the copper powder content (mass%) to the average particle diameter (μm) of the copper powder when the metal composition in the metal layer is 100% by mass to a predetermined value or higher. Furthermore, the inventors of this application discovered that the double-layer disk exhibits the effects described in (b) and (c) in addition to the effect described in (a).

[0090] The double-layer disk 10 of this embodiment is configured to have a carbon layer 1 and a metal layer 2. In the double-layer disk 10, the metal layer 2 can be soldered to the riser plate without a surface plating. Furthermore, the metal layer 2 contains copper powder. When the content (mass%) of the copper powder in the metal layer 2 is set as 'a' (assuming the metal composition in the metal layer 2 is 100% by mass), and the average particle size (μm) of the copper powder is set as 'b', the following conditions are met:

[0091] a / b≧0.34.

[0092] According to the double-layer disk 10 of this embodiment, due to the effects of (a) to (c), a double-layer disk that can be soldered to the riser without plating, has excellent metal layer strength and low resistivity can be realized.

[0093] From the viewpoint of improving the effect of (a) to (c), a / b is preferably 0.45 or more, and more preferably 0.67 or more.

[0094] Furthermore, in the double-layer disk 10 of this embodiment, when the metal composition in the metal layer 2 is set to 100% by mass, the content of copper powder is preferably 10% by mass or more, more preferably 12% by mass or more, even more preferably 13% by mass or more, and most preferably 13.5% by mass or more.

[0095] Furthermore, the manufacturing method of the commutator 100 in this embodiment includes a coating process and a bonding process. In the coating process, solder is applied to the surface of the metal layer 2 in the double-layer disk 10 having a carbon layer 1 and a metal layer 2 without forming a plating layer. Through the coating process, a solder layer 3 is formed on the surface of the metal layer 2. In the bonding process, the solder-coated metal layer 2 is stacked with the base of the riser plate 20 and then heated to bond the metal layer 2 to the base of the riser plate 20.

[0096] Furthermore, in the manufacturing method of the commutator 100 of this embodiment, the metal layer 2 contains copper powder. Moreover, when the content (mass%) of copper powder in the metal layer 2 is set as 'a' (assuming the metal composition in the metal layer 2 is 100% by mass), and the average particle size (μm) of the copper powder is set as 'b', the following conditions are met:

[0097] a / b≧0.34.

[0098] Thus, a commutator 100 can be manufactured, which includes a double-layer disk 10 that can be soldered to the riser without plating, has excellent strength and low resistivity.

[0099] Based on the aforementioned inequality "a / b", the smaller the average particle size of the copper powder, the less copper powder content (mass%) required to achieve a double-layer disk with improved strength, solder wettability, and resistivity. Therefore, from the viewpoint of reducing the amount of copper powder used (mass%), a smaller average particle size of the copper powder is better.

[0100] Another embodiment of the present invention may have the following structure.

[0101] <1> A double-layer disk having a carbon layer and a metal layer, wherein the metal layer can be soldered to a riser without a plating layer on its surface, the metal layer contains copper powder, and when the metal composition in the metal layer is set to 100% by mass, the content of the copper powder is 10% by mass or more.

[0102] <2> A double-layer disk having a carbon layer and a metal layer, wherein the metal layer can be soldered to a riser plate without a surface plating, the metal layer containing copper powder, wherein when the content (mass%) of copper powder in the metal layer is set to 100% by mass, and the average particle size (μm) of the copper powder is set to b, the following condition is met:

[0103] a / b≧0.34.

[0104] <3> According to <1> or <2>, the average particle size of the copper powder is less than 30 μm.

[0105] <4> A double-layered disk according to any one of <1> to <3>, wherein the metal layer comprises brass powder.

[0106] <5> A double-layered disk according to any one of <1> to <4>, wherein the metal layer comprises brass powder, copper powder and tin.

[0107] <6> According to <4> or <5> of the double-layer disk, when the metal composition in the metal layer is set to 100% by mass, the content of brass powder is 80% by mass or less.

[0108] <7> According to <5> the double-layer disk, in the metal layer, when the metal composition in the metal layer is set to 100% by mass, the tin content is 5% to 15% by mass.

[0109] <8> A double-layered disk according to any one of <1> to <7>, wherein the average particle size of the copper powder is 15 μm or more.

[0110] <9> A double-layered disk according to any one of <1> to <8>, wherein the metal layer does not contain carbon.

[0111] <10> A commutator comprising: a double-layer disk according to any one of <1> to <9>, and a riser plate joined to a metal layer side in the double-layer disk, the metal layer being solder-bonded to the riser plate without a surface plating.

[0112] <11> A method for manufacturing a commutator includes: a coating step of coating solder onto the surface of the metal layer in a double-layer disk having a carbon layer and a metal layer without forming a plating layer; and a bonding step of stacking the solder-coated metal layer with a riser plate matrix and then heating it to bond the metal layer with the riser plate matrix, wherein the metal layer contains copper powder, and when the metal composition in the metal layer of the double-layer disk is set to 100% by mass, the content of the copper powder is 10% by mass or more.

[0113] <12> A method for manufacturing a commutator includes: a coating step of coating solder onto the surface of the metal layer in a double-layer disk having a carbon layer and a metal layer without forming a plating layer; and a bonding step of stacking the solder-coated metal layer with a riser plate matrix and then heating it to bond the metal layer to the riser plate matrix, wherein the metal layer contains copper powder, and when the content (mass%) of copper powder is set as a, where the metal composition in the metal layer is 100% by mass, and the average particle size (μm) of the copper powder is set as b, the following condition is met:

[0114] a / b≧0.34.

[0115] <13> The manufacturing method of the commutator according to <11> or <12>, wherein the average particle size of the copper powder is less than 30 μm.

[0116] <14> A method for manufacturing a commutator according to any one of <11> to <13>, wherein the metal layer comprises brass powder.

[0117] [Example]

[0118] The present invention will be described in more detail below through embodiments, but the present invention is not limited to these embodiments.

[0119] Furthermore, the measurement methods in the following examples and comparative examples are described below.

[0120] <Determination Method>

[0121] [Resistivity, flexural strength, solder wettability]

[0122] The materials of the metal layers in the examples and comparative examples were uniformly mixed, pressed into shape, and then heated at 320°C in a reducing gas environment to produce test pieces of the metal layers. The obtained test pieces were elongated strips in the pressing direction.

[0123] Resistivity: Current was passed through the test piece along its length, and the resistivity was measured by voltage drop method according to JIS C 2820.

[0124] Bending strength: The load at which the test piece fractured was determined according to JIS C 2820 using a material testing machine (trade name: Universal Material Testing Machine Model 5966, manufactured by Instron).

[0125] Solder wettability: 0.09 g of solder paste was applied to the test piece to a height of 3 mm. The test piece coated with the solder paste was then heated at 300°C for 2 minutes using a heating plate. The height of the melted solder paste was measured, and this measured value was taken as the solder wettability. Furthermore, the solder paste used in this method is the same as the solder actually used in the manufacture of the commutator.

[0126] [Average particle size of copper powder contained in the metal layer in the double-disc state]

[0127] The fabricated double-layered disc was embedded in resin. The resin embedding was then ground from the metal layer side until the metal layer was visible, and then ground from the side until the metal layer was visible again. Microscopic images (photographs) of the visible metal layer were then obtained from the ground resin embedding. Copper powder was identified based on these microscopic images, and the particle size of 50 copper powder particles was measured. The average value of the measured copper powder particle size was taken as the average particle size of the copper powder.

[0128] (Examples 1 to 7, Comparative Examples 1 to 5)

[0129] The following materials were used to create a metal layer, a double-layered disk.

[0130] Brass powder: Brass powder with an average particle size of 34 μm and a zinc content of 30% by mass.

[0131] Tin powder: average particle size 43 μm

[0132] Silver powder: average particle size 18 μm

[0133] Copper powder: electrolytic copper powder with an average particle size of 20 μm, electrolytic copper powder with an average particle size of 25 μm, electrolytic copper powder with an average particle size of 30 μm, and electrolytic copper powder with an average particle size of 35 μm.

[0134] The metal layer materials from Examples 1 to 7 and Comparative Examples 1 to 5 were prepared according to the composition ratios in Table 1 and mixed uniformly using a mixer to obtain metal layer material mixtures. The metal layer material mixtures were then pressed into strip-shaped test pieces. The resistivity, flexural strength, and solder wettability of the prepared test pieces were then measured. Furthermore, a resistivity of 2.1 μΩ·m or less was considered to have a resistivity-reducing effect, a flexural strength of 8 MPa or more was considered to have a strength-increasing effect, and a solder wettability of 1.9 mm or less was considered to have a solder wettability-improving effect. The measurement results are shown in Table 1. In Table 1, the unit for the metal content of each metal layer is mass %, indicating the proportion when the metal content in the metal layer is set to 100% by mass.

[0135] The metal layer material mixture and carbon powder were sequentially added into a mold, pressed into shape, and then calcined at 320°C in a reducing gas environment to produce a double-layer disk. The average particle size of the copper powder contained in the metal layer of the fabricated double-layer disk was measured. The results are shown in Table 2.

[0136] [Table 1]

[0137] Table 1

[0138]

[0139]

[0140]

[0141] [Table 2]

[0142] Table 2

[0143]

[0144] According to the comparison between Examples 1 to 5 and Comparative Examples 1 to 2 in Table 1, when the copper powder content is 10% by mass or more, it has the effects of reducing resistivity, increasing strength, and improving solder wettability. Furthermore, it can be seen that in Examples 1 to 5, if the copper powder content increases, the effects of reducing resistivity, increasing strength, and improving solder wettability tend to increase.

[0145] According to Examples 2, 6, and 7 in Table 1, when the average particle size of the copper powder is below 30 μm, it has the effects of reducing resistivity, increasing strength, and improving solder wettability. Furthermore, it can be seen that if the average particle size of the copper powder decreases, the effects of reducing resistivity, increasing strength, and improving solder wettability tend to increase.

[0146] The composition of the metal layer in Comparative Examples 1, 3 to 5 is substantially the same as that in the embodiments and comparative examples in Patent Document 4. A comparison of Example 2 with Comparative Examples 1, 3 to 5 shows that Example 1, compared to Comparative Examples 1, 3 to 5, has the effects of reducing resistivity, increasing strength, and improving solder wettability.

[0147] Table 2 shows the fabrication of a double-layered disk with the metal layer composition of Example 2, and the average particle size of the copper powder contained in the metal layer in the double-layered disk state was measured. The results show that the average particle size of the copper powder used to fabricate the metal layer is the same as the average particle size of the copper powder contained in the metal layer in the double-layered disk state as the product. That is, it can be seen that the average particle size of the copper powder used to fabricate the metal layer is maintained even in the double-layered disk state as the product.

[0148] (The relationship between the copper powder content (mass%) and the average particle size (μm) of the copper powder)

[0149] Regarding solder wettability, it is believed to be correlated with the total surface area of ​​copper powder contained in 100 g of the metal composition of the metal layer. Specifically, it is believed that the higher the total surface area of ​​the copper powder, the better the solder wets the metal layer (i.e., the lower the value of "solder wettability"). Therefore, the correlation between the total surface area of ​​copper powder contained in 100 g of the metal composition of the metal layer and solder wettability has been confirmed.

[0150] Here, "the total surface area of ​​copper powder contained in 100 g of the metal composition of the metal layer" can be calculated according to the following formula.

[0151] "Total surface area of ​​copper powder contained in 100 g of metal composition of metal layer" = "Surface area of ​​1 copper powder particle" × "Number of copper powder particles contained in 100 g of metal composition of metal layer" = "Surface area of ​​1 copper powder particle" × "Total volume of copper powder particles contained in 100 g of metal composition of metal layer" ÷ "Volume of 1 copper powder particle".

[0152] Furthermore, if we assume the density of copper (g / cm³) 3 A) The mass (g) of copper powder contained in 100 g of the metal layer: a) The average particle size (μm) of the copper powder: b) Then

[0153] "The total surface area of ​​copper powder contained in 100 g of the metallic component of the metal layer" = (4π(b / 2×10)) -4 ) 2 ×(a / A)÷(4 / 3×π×(b / 2×10 -4 ) 3 ) = (6 / A × 10 4 )×a / b.

[0154] According to the above formula, "the total surface area of ​​copper powder contained in 100 g of the metal component of the metal layer" is related to a÷b, i.e., (mass of copper powder contained in 100 g of the metal component of the metal layer (g))÷ (average particle diameter of copper powder (μm)). In addition, "mass of copper powder contained in 100 g of the metal component of the metal layer (g)" is "the content of copper powder (mass%) when the metal component in the metal layer is set to 100% by mass".

[0155] Therefore, referring to Table 1, for Examples 1 to 7 and Comparative Examples 1 to 5, which used copper powder, the correlation between the copper powder content / average particle size of the copper powder and properties such as solder wettability is summarized in Table 3 below.

[0156] [Table 3]

[0157] Table 3

[0158]

[0159] Figure 5 This is a graph showing the relationship between copper powder content / average particle size of copper powder and solder wettability. According to... Figure 5 It is evident that "the content of copper powder (mass%) ÷ (average particle size of copper powder) when the metal composition in the metal layer is set to 100% by mass" is highly correlated with "solder wettability".

[0160] exist Figure 5 In the equation, when we set "the content of copper powder (mass%) ÷ (average particle size of copper powder) when the metal composition in the metal layer is 100% by mass" as x and "solder wettability" as y, the correlation between x and y is approximately the relationship "y = -0.89x + 2.2".

[0161] Here, as mentioned above, when the solder wettability is 1.9 mm or less, it is considered to have the effect of improving solder wettability. Therefore, according to the aforementioned formula, when the solder wettability is 1.9 mm or less, the content of copper powder (mass%) ÷ (average particle size of copper powder) (a / b) is as follows.

[0162] a / b≧0.34.

[0163] Furthermore, as mentioned above, when the resistivity is below 2.1 μΩ·mm, it is considered to have the effect of reducing resistivity, and when the bending strength is above 8 MPa, it is considered to have the effect of increasing strength. Based on the same points mentioned above, graphs showing the relationship between a / b and resistivity, and graphs showing the relationship between a / b and bending strength, were derived. Moreover, it was confirmed that when a / b ≥ 0.34, (1) the resistivity is below 2.1 μΩ·m, and (2) the bending strength is above 8 MPa. Therefore, it can be seen that by satisfying a / b ≥ 0.34, it has the effects of reducing resistivity, increasing strength, and improving solder wettability.

[0164] [Industry availability]

[0165] This invention can be used in commutators that utilize carbon.

[0166] Explanation of icon numbers

[0167] 1: Carbon layer

[0168] 2: Metal layer

[0169] 2a: Surface

[0170] 10: Double-layered disc

[0171] 20: Lifting tablets

[0172] 100: Commutator

Claims

1. A double-layered disk having a carbon layer and a metal layer, wherein in the double-layered disk, The metal layer can be soldered to the riser plate without a surface plating. The metal layer contains copper powder. When the metal composition in the metal layer is set to 100% by mass, the content of copper powder is 10% by mass or more.

2. A double-layered disk having a carbon layer and a metal layer, wherein in the double-layered disk, The metal layer can be soldered to the riser plate without a surface plating. The metal layer contains copper powder. When the content (mass%) of copper powder in the metal layer is set to 100% by mass, and the average particle size (μm) of the copper powder is set to b, the following conditions are met: a / b≧0.

34.

3. The double-layer disk according to claim 1 or 2, wherein the average particle size of the copper powder is less than 30 μm.

4. The double-layer disk according to claim 1 or 2, wherein the metal layer comprises brass powder.

5. The double-layer disk according to claim 1 or 2, wherein the metal layer comprises brass powder, copper powder, and tin.

6. The double-layer disk according to claim 4, wherein when the metal composition in the metal layer is set to 100% by mass, the content of the brass powder is 80% by mass or less.

7. The double-layer disk according to claim 5, wherein in the metal layer, when the metal composition in the metal layer is set to 100% by mass, the tin content is 5% to 15% by mass.

8. The double-layer disk according to claim 1 or 2, wherein the average particle size of the copper powder is 15 μm or more.

9. The double-layer disk according to claim 1 or 2, wherein the metal layer does not contain carbon.

10. A commutator, comprising: The double-layer disk according to claim 1 or 2; as well as The lifting plate is joined to the metal layer side of the double-layer disk. The metal layer is soldered to the riser plate without any surface plating.

11. A method for manufacturing a commutator, comprising: In the coating process, solder is applied to the surface of the metal layer in a double-layered disk having a carbon layer and a metal layer without forming a plating layer. as well as In the bonding process, the metal layer coated with solder is stacked with the riser substrate and then heated to bond the metal layer to the riser substrate. The metal layer contains copper powder. When the metal composition in the metal layer of the double-layer disk is set to 100% by mass, the content of copper powder is 10% by mass or more.

12. A method for manufacturing a commutator, comprising: In the coating process, solder is applied to the surface of the metal layer in a double-layered disk having a carbon layer and a metal layer without forming a plating layer. as well as In the bonding process, the metal layer coated with solder is stacked with the riser substrate and then heated to bond the metal layer to the riser substrate. The metal layer contains copper powder. When the content (mass%) of copper powder in the metal layer is set to 100% by mass, and the average particle size (μm) of the copper powder is set to b, the following conditions are met: a / b≧0.

34.

13. The method for manufacturing a commutator according to claim 11 or 12, wherein the average particle size of the copper powder is less than 30 μm.

14. The method of manufacturing a commutator according to claim 11 or 12, wherein the metal layer comprises brass powder.

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