SWASH PLATE AND METHOD OF MANUFACTURING SWASH PLATE

Abstract

A swash plate includes 34.5 to 43.0 wt % of copper (Cu) and 0.5 to 2.8 wt % of silicon (Si), with a remainder of aluminum (Al) and other inevitable impurities.

Claims

1. A swash plate, comprising: 34.5 to 43.0 wt % of copper (Cu) and 0.5 to 2.8 wt % of silicon (Si), with a remainder of aluminum (Al) and other inevitable impurities.

2. The swash plate of claim 1, wherein the swash plate includes a plurality of core pin holes, the core pin holes being formed toward a center along an outer circumferential surface thereof.

3. The swash plate of claim 2, wherein the core pin holes comprise a diameter of or less of a thickness of the swash plate.

4. The swash plate of claim 1, wherein the swash plate has a primary Al.sub.2Cu phase and an AlAl.sub.2Cu lamella structure.

5. The swash plate of claim 4, wherein the swash plate has a primary Al.sub.2Cu phase fraction of 10 to 50 vol % and an elastic modulus of 120 GPa or more.

6. The swash plate of claim 1, wherein the swash plate has a tensile strength of 400 MPa or more and a castability evaluation factor (C) of 2.0 or more, as defined by Equation 1 below:
Castability evaluation factor (C)=liquidus temperature (K)/{liquidus temperature (K)(quantity of heat (Q)composition (F))}Equation 1:

7. A method of manufacturing a swash plate, comprising: preparing an aluminum alloy melt comprising 34.5 to 43.0 wt % of copper (Cu) and 0.5 to 2.8 wt % of silicon (Si), with a remainder of aluminum (Al) and other inevitable impurities; casting the aluminum alloy melt using a mold having a plurality of core pins; and removing the core pins from the mold and separating the swash plate from the mold.

8. The method of claim 7, wherein the casting is performed through gravity casting or centrifugal casting.

9. The method of claim 7, wherein the casting is performed at a temperature of 595 to 625 C.

10. The method of claim 7, wherein the core pins have a thickness of or less of a thickness of the swash plate.

11. The method of claim 7, wherein the swash plate has a primary Al.sub.2Cu phase fraction of 10 to 50 vol % and an elastic modulus of 120 GPa or more.

12. The method of claim 7, wherein the swash plate has a tensile strength of 400 MPa or more and a castability evaluation factor (C) of 2.0 or more, as defined by Equation 1 below:
Castability evaluation factor (C)=liquidus temperature (K)/{liquidus temperature (K)(quantity of heat (Q)composition (F))}Equation 1:

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above and other objects, features and advantages of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0031] FIG. 1 illustrates a swash plate according to an embodiment of the present disclosure;

[0032] FIG. 2 illustrates a microstructure of the swash plate according to an embodiment of the present disclosure;

[0033] FIG. 3 illustrates the agglomeration and coarse growth of primary Al.sub.2Cu phase in the microstructure of an aluminum alloy having a Cu content that exceeds 43.0 wt %;

[0034] FIG. 4 is a graph illustrating changes in an elastic modulus depending on the Cu content;

[0035] FIG. 5 is a graph illustrating a primary Al.sub.2Cu phase fraction depending on the Cu content;

[0036] FIG. 6 is a graph illustrating changes in a tensile strength depending on the Si content; and

[0037] FIG. 7 is a graph illustrating a castability evaluation factor (C) depending on the Cu content.

DETAILED DESCRIPTION

[0038] Hereinafter, a detailed description will be given of preferred embodiments of the present disclosure with reference to the appended drawings, but such embodiments are not to be construed as limiting the present disclosure. Throughout the drawings, the same reference numerals refer to the same or like parts, and may be described with reference to contents depicted in the other drawings. Furthermore, descriptions which are deemed to be readily apparent to those skilled in the art or repetitive may be omitted.

[0039] According to an embodiment of the present disclosure, a swash plate 100 may be composed mainly of Al and includes 34.5 to 43.0 wt % of Cu, 0.5 to 2.8 wt % of Si, and other inevitable impurities.

[0040] The aluminum alloy according to the present disclosure may be different from the hypereutectic aluminum alloy used for a conventional swash plate because it includes a Cu content of 34.5 wt % or more and a Si content of 0.5 to 2.8 wt %, which is notably lower than the 12.6 wt % or more of Si in the conventional hypereutectic aluminum alloy.

[0041] Therefore, both wear resistance and high strength required for the swash plate may be satisfied.

[0042] More specifically, the Cu content of the swash plate according to the present disclosure may be preferably set within the range of 34.5 to 43.0 wt %.

[0043] If the Cu content is less than 34.5 wt %, the elastic modulus of 120 GPa or more may not be not ensured. In contrast, if the Cu content exceeds 43.0 wt %, the primary Al.sub.2Cu phase corresponding to an intermetallic compound may be formed in an amount of 50% or more in the microstructure, and thus the properties of the intermetallic compound may be exhibited, undesirably incurring problems related to brittleness and processability and making it impossible to apply the resultant aluminum alloy to a swash plate.

[0044] Meanwhile, Si may be added to enhance the strength of the aluminum alloy, which may contain an excess of Cu. When the Si content falls in the range of 0.5 to 2.8 wt %, a tensile strength of 400 to 550 MPa may be ensured. If the Si content is less than 0.5 wt % or exceeds 2.8 wt %, a tensile strength of less than 400 MPa may result, making it impossible to ensure high strength.

[0045] Hence, the Si content is preferably set within the range from 0.5 to 2.8 wt %.

[0046] FIG. 1 illustrates the swash plate 100 according to an embodiment of the present disclosure. As illustrated in FIG. 1, the swash plate according to the embodiment of the present disclosure may be configured such that a plurality of core pin holes 110 is formed toward the center along the outer circumferential surface thereof.

[0047] The diameter of the core pin holes is preferably set to or less of the thickness of the swash plate. If the diameter of the core pin holes, which are formed to realize lightweightness, exceeds of the thickness of the swash plate, structural stability may not be ensured. The plurality of core pin holes is disposed radially toward the center along the outer circumferential surface of the swash plate, and the maximum number thereof may be 36 (such that the angle defined between adjacent core pin holes=10).

[0048] The number of core pin holes may fall in the range of 2 to 36, and the diameter thereof may be or less of the thickness of the swash plate, and the angle defined between adjacent core pin holes may be in the range of 10 to 180.

[0049] FIG. 2 illustrates a microstructure of the swash plate according to an embodiment of the present disclosure, and FIG. 3 illustrates an agglomeration and coarse growth of primary Al.sub.2Cu phase in the microstructure of the aluminum alloy having a Cu content that exceeds 43.0 wt %.

[0050] As illustrated in FIGS. 2 and 3, when the swash plate according to an embodiment of the present disclosure comprises 34.5 to 43.0 wt % of Cu and 0.5 to 2.8 wt % of Si, the primary Al.sub.2Cu phase may be uniformly formed so as to have a phase fraction of 10 to 50 vol %, thereby ensuring superior elastic modulus and tensile strength. If the Cu content exceeds 43.0 wt %, agglomeration and coarse growth may occur, thus causing brittleness of the material and deteriorating processability (i.e. potentially damaging tools).

[0051] In addition, a method of manufacturing the swash plate according to an embodiment of the present disclosure may include preparing an aluminum alloy melt, casting the aluminum alloy melt to form a swash plate, and separating the swash plate from a mold.

[0052] In the preparation step, the aluminum alloy melt preferably comprises 34.5 to 43.0 wt % of Cu, and 0.5 to 2.8 wt % of Si, with the remainder of Al and other inevitable impurities.

TABLE-US-00001 TABLE 1 Cu content Elastic modulus Primary Al.sub.2Cu phase fraction (wt %) (GPa) (vol %) C. Ex. 1 33 0 C. Ex. 2 34 119 5 Ex. 1 35 123 10 Ex. 2 37 130 20 Ex. 3 39 137 30 Ex. 4 41 145 40 Ex. 5 43 154 50 C. Ex. 3 45 163 60

[0053] Table 1 shows the primary Al.sub.2Cu phase fraction and elastic modulus depending on the Cu content, in the examples and comparative examples. FIG. 4 is a graph illustrating changes in the elastic modulus depending on the Cu content, and FIG. 5 is a graph illustrating changes in the primary Al.sub.2Cu phase fraction depending on the Cu content.

[0054] As shown in Table 1 and FIGS. 4 and 5, if the Cu content is less than 34.5 wt %, the primary Al.sub.2Cu phase fraction is decreased, and thus the elastic modulus may be less than 120 GPa, which does not satisfy the required elastic modulus. In contrast, if the Cu content exceeds 43 wt %, the primary Al.sub.2Cu phase fraction is greater than 50%, thus causing agglomeration and coarse growth thereof, undesirably resulting in brittleness and poor processability. Hence, the Cu content may be set within the range from 34.5 to 43 wt %.

TABLE-US-00002 TABLE 2 Si content Tensile strength (wt %) (MPa) C. Ex. A 0 65 Ex. A 0.5 540 Ex. B 1.0 540 Ex. C 1.5 500 Ex. D 2.0 470 Ex. E 2.5 430 C. Ex. B 3.0 380 C. Ex. C 4.0 260

[0055] Table 2 shows changes in tensile strength depending on the Si content in the examples and comparative examples, and FIG. 6 is a graph illustrating changes in tensile strength depending on the Si content.

[0056] As is apparent from Table 2 and FIG. 6, when the Si content falls in the range from 0.5 to 2.8 wt %, superior tensile strength of 400 MPa or more may be ensured. In contrast, if the Si content is less than 0.5 wt % or exceeds 2.8 wt %, tensile strength may be drastically reduced to a level lower than 400 MPa. Hence, the Si content is preferably set within the range from 0.5 to 2.8 wt %.

[0057] After the preparation of the aluminum alloy melt, the swash plate may be formed through casting. The casting process according to an embodiment of the present disclosure is preferably gravity casting or centrifugal casting. Alternatively, a sand casting process may be applied.

[0058] Since the aluminum alloy melt used in the method of manufacturing the swash plate according to the present disclosure may have a low liquidus temperature of 550 to 575 C. compared to conventional hypereutectic aluminum alloys, coarse growth of the microstructure may not readily occur with a decrease in cooling rate, and thus gravity casting or high-pressure casting may be applied.

[0059] In the present disclosure, the casting process is preferably carried out at a temperature of 595 to 625 C.

[0060] The liquidus temperature of the aluminum alloy melt used in the present disclosure may be a maximum of 575 C. In order to ensure fluidity of the melt, the casting process is preferably performed at a minimum of 595 C., which is at least 20 C. higher than the liquidus temperature.

[0061] If the casting temperature is more than 50 C. higher than the liquidus temperature, the size of the resulting primary Al.sub.2Cu phase may increase, and the high strength and wear resistance of the product may deteriorate due to the generation of pores by the hydrogen gas. Hence, the casting temperature is preferably set to a range of 595 to 625 C.

TABLE-US-00003 TABLE 3 Quantity of heat Q Liquidus Heat Latent (Latent Castability Al Cu Temp. K capacity heat heat/Heat Composition F evaluation (wt %) (wt %) ( C.) (J/gK) (J/g) capacity) (Cu/Al) factor C C. Ex. 1 67 33 545 0.733 381 520 0.49 1.89 C. Ex. 2 66 34 550 0.728 381 523 0.52 1.96 Ex. 1 65 35 554 0.723 381 527 0.54 2.05 Ex. 2 63 37 556 0.713 381 534 0.59 2.31 Ex. 3 61 39 567 0.702 381 543 0.64 2.58 Ex. 4 59 41 574 0.693 380 548 0.69 2.59 Ex. 5 57 43 580 0.682 380 557 0.75 3.63 C. Ex. 3 55 45 587 0.672 380 565 0.82 4.72

[0062] Table 3 shows the results of calculation of the castability evaluation factor in the examples and comparative examples, and FIG. 7 is a graph illustrating the castability evaluation factor (C) depending on the Cu content.

[0063] The castability evaluation factor (C) is calculated by the following Equation 1.

Castability evaluation factor (C)=liquidus temperature (K)/{liquidus temperature (K)(quantity of heat (Q)composition (F))}Equation 1:

[0064] As is apparent from Table 3 and FIG. 7, the castability evaluation factor according to the examples of the present disclosure may be as high as 2.0 or more, and the agglomeration and coarse growth of the resulting primary Al.sub.2Cu phase may be prevented from occurring, thereby ensuring high strength and wear resistance and exhibiting superior processability.

[0065] Although the preferred embodiments of the present disclosure have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the disclosure as disclosed in the accompanying claims.