JPH04350135A - Combination structure for sliding members - Google Patents

Abstract

PURPOSE:To provide a combination improving as possible sliding characteristics of two sliding members sliding relatively abutting mutually. CONSTITUTION:In a combination of two sliding member of first and second members abutting each other and sliding relatively, the first sliding member is made of alumina composite material which is formed by impregnating aluminum alloy into hybrid formed body which consists of boric aluminum whiskers alumina short fiber, and the other sides, the second sliding member consists of a cast iron material made to be light in weight by punching, and is improved in wear resistance and sliding performance and is usable in high speed operation.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compositional combination of sliding members such as a vane (blade) member and a rotor member for a rotary compressor, for example.

0002

[Prior Art] For example, a rotary compressor used in an air conditioner includes a rotary cylinder, a rotor that is eccentrically rotatably supported within the rotary cylinder, and a rotor that is slidable in a vane groove on the inner peripheral surface of the rotary cylinder. It consists of a vane that is fitted into the rotor and always slides on the rotor surface, a front head and a rear head on both sides of the cylinder, etc. When the drive motor rotates, the rotor rotates eccentrically within the cylinder due to the rotation of the cam on the camshaft, whereby refrigerant gas flows into the cylinder from the suction port, is compressed, and is discharged from the discharge port. Ru. At this time, the vanes perform reciprocating sliding (protrusion and retraction) motions at a considerable speed in the radial direction of the rotor in accordance with the eccentric rotation of the rotor. Incidentally, relative sliding members such as the rotor and vanes that slide in contact with each other have conventionally been generally made of steel or cast iron from the viewpoint of wear resistance and coefficient of thermal expansion. However, in recent years, inverter-based phase control has become mainstream in rotary compressors for air conditioners such as those described above, and high-speed rotation has become an unavoidable requirement.

However, the above-mentioned steel and cast iron naturally have a high specific gravity and a large mass. For this reason, for example, in the case of a rotor, the load on the rotor bearing is large, and the swing width of the crankshaft is also large. Therefore, problems such as contact between the rotor and stator in the motor section arise, and there is a drawback that high speed rotation above a certain level cannot be supported.

[0004] Also, regarding vanes, when the vanes rotate at high speeds exceeding a predetermined value, their inertia increases, making it impossible for their reciprocating motion to follow the rotation of the rotor, resulting in a problem of loss of sealing performance and gas leakage. .

[0005] Under these circumstances, it has been considered to manufacture each sliding member such as the rotor and vanes from an aluminum alloy that is lightweight and has high wear resistance.

However, in the case of a single aluminum alloy, the coefficient of thermal expansion is approximately twice that of iron, so it has problems such as excessive fluctuations in clearance with other iron parts and low wear resistance. There are problems and it cannot be put into practical use as is.

[0007] Therefore, recently, improvements in wear resistance,
Aluminum composite materials containing various reinforcing materials have been devised to reduce the coefficient of thermal expansion.

[0008] For example, a composite material made of SiC whiskers and aluminum alloy (Japanese Patent Application Laid-Open No. 63-230983)
, an aluminum composite material in which ceramic particles are dispersed as a reinforcing material (Japanese Unexamined Patent Publication No. 62-30838).

[0009]

[Problem to be solved by the invention] However, the above-mentioned Japanese Patent Application Laid-Open No. 6
Although the thermal expansion coefficient of the composite material made of SiC whiskers and aluminum alloy disclosed in Publication No. 3-230983 is sufficiently reduced, it has the following problems in terms of wear resistance and aggressiveness to the mating material. There is.

That is, SiC whiskers have the characteristic of significantly improving strength and hardness when combined with metals such as aluminum alloys, but since the Mohs hardness of the SiC whiskers is extremely high at 9, it is difficult to slide. If it falls off the matrix during movement, it acts like an abrasive on the sliding surface, causing significant wear on the aluminum composite body and the mating material. In other words, there is a problem in that it is highly aggressive towards the opposing material.

On the other hand, for example, Al2O3, Si3N4, SiC, B
Aluminum composites have also been invented in which ceramic particles such as N are mixed as reinforcing materials, but due to their shape, ceramic particles like the ones mentioned above are less likely to fall off sliding surfaces than short fibers or whiskers. It has the disadvantage that it occurs easily, and there is still a problem in terms of wear resistance.

0012

[Means for solving the problem] (1) To solve the above problem, first, the first
In the combination of the second two sliding members, the first sliding member is a hybrid molded body of aluminum borate whiskers (9Al2O3.2B2O3) and alumina short fibers (Al2O3). This is accomplished by forming the second sliding member from an aluminum composite material impregnated with an aluminum alloy, while forming the second sliding member from a cast iron material that has been made lighter by drilling.

(2) In that case, the total volume fraction of the hybrid molded body of aluminum borate whiskers and short alumina fibers in the first sliding member is determined as the total volume percentage of the entire sliding member as in the invention as claimed in claim 2. 25-3
By setting it to 0% and further setting the blending ratio of the aluminum borate whiskers and alumina short fibers in the molded article to 0.5 to 2.0, the above conventional problems can be effectively solved. .

(3) Furthermore, the above problem can be more effectively solved by setting the Si content in the aluminum alloy to be impregnated into the hybrid compact of aluminum borate whiskers and short alumina fibers to 20 to 30%. will be done.

[0015]

[Function] (1) That is, as described above, the above-mentioned problems in the prior art such as coefficient of thermal expansion, abrasion resistance, and aggressiveness to mating materials can be solved as shown in the invention described in claim 1. To,
First, the first sliding member on one side is impregnated with molten aluminum alloy under a predetermined pressure condition into a hybrid molded body formed by mixing alumina short fibers and aluminum borate whiskers, and then solidified. This can be achieved by using a sliding material made of a cast iron material, and by using a cast iron sliding member whose weight has been reduced by drilling the second sliding member on the other side.

For example, when forming the first sliding member, if short alumina fibers or aluminum borate whiskers are individually composited with aluminum, an aluminum composite material having excellent wear resistance and a low coefficient of thermal expansion can be obtained. However, on the other hand, short alumina fibers have some problems in their ability to attack the mating material during sliding, and the coefficient of thermal expansion is also slightly higher than that of current blade cast iron materials. . On the other hand, a composite material of aluminum borate whiskers and aluminum has a problem in that abnormal wear occurs during a wear resistance test under severe sliding conditions.

However, when a sliding material is formed by impregnating an aluminum alloy into a hybrid molded body formed by mixing these alumina short fibers and aluminum borate whiskers to form a composite, the alumina short fibers and boric acid whiskers are mixed together to form a sliding material. By rationally combining the respective advantages of aluminum whiskers, it is possible to obtain an aluminum composite material that is less aggressive to mating materials and exhibits good wear resistance even under severe sliding conditions. In addition, the coefficient of thermal expansion can be further lowered than when using only short alumina fibers.
Furthermore, the bending strength can be increased compared to the case of aluminum borate whiskers alone.

Furthermore, another operational advantage is that the blending ratio of the alumina short fibers and the aluminum borate whiskers can be varied over a wide range. Any of the reinforcing materials effectively contributes to improving wear resistance and reducing the coefficient of thermal expansion. Therefore, in order to obtain a composite material with good characteristics depending on the application, the range of the above-mentioned compounding ratio can be set broadly, and the ratio can be relatively freely selected according to the required characteristics in relation to the mating member. Become.

Therefore, the first sliding member is most suitable as one side sliding member of a pair of sliding members that abut each other and slide relative to each other.

On the other hand, as a second sliding member corresponding to the first sliding member, a conventional cast iron member originally has a coefficient of thermal expansion,
Although both the abrasion resistance and the wear resistance are favorable, there is a problem in that the mass is large.

However, as mentioned above, if a cast iron material is used as the second sliding member and the weight is reduced by drilling holes in it, the mass becomes smaller and the same problem can be effectively solved. Become.

(2) Regarding the volume fraction and blending ratio of each material, for example, as shown in the invention described in claim 2, the total volume fraction of alumina short fibers and aluminum borate whiskers is 25 It has been confirmed from the results of experiments that it is optimal to obtain the above-mentioned effect when the blending ratio of the two is in the range of 0.5 to 2.0.

(3) In the above case, the aluminum alloy impregnated into the hybrid molded body of aluminum borate whiskers and short alumina fibers has a Si content of 20%.
A content of ~30% is most desirable because the coefficient of thermal expansion is low, the abrasion resistance is good, and the attack on the mating material is small.

[0024]

Effects of the Invention As is clear from the above description, according to the combination structure of the sliding members of the present invention, both of them have low aggressiveness to the mating material, and each of them is as light as possible and has a low coefficient of thermal expansion. Moreover, it becomes possible to provide a combination structure of sliding members that has high friction and wear characteristics and is suitable for high-speed rotation such as for rotary compressors.

Therefore, even if applied to the rotor member and vane member of a rotary compressor for an air conditioner, high speed rotation is possible, stable clearance can be maintained, and the overall weight is reduced. , it is possible to reliably eliminate the drawbacks of conventional sliding members.

[0026]

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail.

First, in this embodiment, a rotor and a vane of a rotary compressor for an air conditioner were selected as the first and second sliding members that contact each other and slide relative to each other.

[0028] Then, aluminum borate whiskers and short alumina fibers are selected as constituent materials of the first sliding member constituting either the rotor or the vane,
Two types of samples with a total volume ratio of 25% and 30% were selected, and each volume ratio (2
By selecting two types of aluminum borate whiskers/alumina staple fibers with different blending ratios of 0.5 and 2.0 in the 5% and 30% samples, a total of 8 types of hybrid samples were created. After adopting the molded products and preheating them by setting them in a predetermined mold, S
A molten aluminum alloy, which is a matrix material containing i, is injected, sufficiently impregnated and solidified under a pressurized state of about 1 t/cm2 using a plunger, for example, to form a molten aluminum alloy for a rotary compressor such as a vane or a rotor. A sliding member of No. 1 was manufactured. In this case, as shown in the following (Table 1), the aluminum alloy that is the matrix material has a Si content of 24.5% by weight, a Cu content of 4.5% by weight, and an Mg content. The amount is 0.94% by weight, the Ni content is 0.99%, and the Fe content is 0.94% by weight.
The content is 0.22%, the Ti content is 0.12% by weight,
Those having a Zn content of 0.01% or less were selected and used.

[0029]

[Table 1]

[0030] The test piece of the sliding member manufactured in this way was then subjected to T6 heat treatment (500°C) based on JIS.
After heating for 4 hours at 200°C, water quenching, and heating again at 200°C for 4 hours to form a precipitated phase, the coefficient of thermal expansion was measured and the wear test was performed using the pin-on-disk friction and wear tester shown in Figure 1. went.

Generally, when the material of the present invention is used for rotary compressor vanes, rotors, etc., it is desirable that its coefficient of thermal expansion is no different from that of the cast iron material forming the periphery of these members such as cylinders.

From this, as shown in the following (Table 2), each volume ratio of aluminum borate whiskers and alumina short fibers is determined so that the volume ratio (Vf) of the entire sliding member of the hybrid molded body is 25 to 30. The coefficient of thermal expansion was measured for each of seven types of samples (A to G), which were appropriately changed within the range of %. The target range of thermal expansion coefficient here is:
Needless to say, the level of the thermal expansion coefficient of the cast iron materials that make up the surroundings of current vanes, rotors, etc. is 10.8/1.
It is in the range of 06·°C to 13.4/106·°C.

[0033]

[Table 2]

From the above (Table 2), the total (TOTAL) volume fraction of aluminum borate whiskers and alumina short fibers (
When the ratio of the short alumina fibers is maximized when Vf) is 25%, this indicates that this is the lower limit of the target range, and in order to have a coefficient of thermal expansion within the target range, at least the hybrid molded body must be It is necessary that the total volume fraction of However, if the TOTAL volume fraction (Vf) of the hybrid molded body exceeds 30%, it becomes necessary to considerably increase the compression ratio in order to increase the TOTAL volume fraction (Vf) during production of the molded body. As a result, the aluminum borate whiskers and short alumina fibers break into small pieces, resulting in a very small aspect ratio, that is, a shape closer to granules rather than whiskers or short fibers, resulting in a problem in which the wear resistance is significantly reduced. .

[0035] In addition, in the manufacturing process of aluminum composite materials such as the material of the present invention, the total volume fraction of sliding members (
It is difficult with current technology to uniformly impregnate a molten aluminum alloy under pressure into a hybrid molded body having a Vf) of 30% or more. Therefore, the total of the hybrid molded body of aluminum borate whiskers and short alumina fibers (TO
It is necessary to set the volume fraction (Vf) in the range of 25 to 30%, and this is actually sufficient.

As described above, in this example, the total volume fraction (Vf) of the hybrid molded body of aluminum borate whiskers and short alumina fibers in the sliding member was set to 25 to 3.
Since the total volume fraction Vf can be set as wide as 0%, the thermal expansion coefficient can of course be controlled by the total volume fraction Vf = 25 to 30%. It is clear from the above (Table 2) that the thermal expansion coefficient can also be controlled by the individual volume fraction ratio with short fibers.

Next, the results of a wear test performed on the first sliding member formed as described above using the pin-on-disk type friction and wear tester shown in FIG. 1 will be described. In FIG. 1, reference numeral 1 indicates the first disk on the fixed side, 2 indicates the second disk on the rotary drive side, 3a,
3b and 3c (3c not shown) each indicate three pin test pieces fixed to the first disk 1 side. Then, the pin test pieces 3a, 3b, 3c and the second disk 2
The amount of wear of the pin test pieces 3a, 3b, 3c and the second disk 2, which is a mating material, is measured by sliding the pin test pieces 3a, 3b, 3c. For the abrasion test, samples (A) to (E) were selected for the abrasion test I from the materials of the invention shown in Table 2, and samples (A), (D), and (E) were selected for the abrasion test II. As comparative materials, (H) to (K) shown below (Table 3)
) materials were selected. Further, as the material of the other party (second disk), for example, Ni-Cr-Mo cast iron, which is commonly used as a rotor material, was used. and,
Wear test I: sliding speed 1 m/sec, surface pressure 645
Under the condition of kgf/cm2, the wear volume of each pin test piece (number 3a, 3b, 3c in FIG. 1) and the second disk (number 2 in FIG. 1) after 7 hours of operation was measured. on the other hand,
As wear test II, sliding speed 1 m/sec, surface pressure 8
The wear volume of the pin test pieces (numerals 3a, 3b, and 3c in FIG. 1) was measured after one hour of operation under strict conditions of 50 kgf/cm2.

[0038]

[Table 3]

The results of the wear test I are as shown in FIG.
Even if the volume fraction (Vf) of whiskers and short fibers is the same, the abrasion resistance is improved compared to the case where alumina short fibers are used alone. In addition, (A) to (with different volume fraction ratios)
None of the samples in E) are based on the current cast iron vane material (J
) has improved wear resistance. Regarding aggression,
All of (A) to (E) show that there is little aggression towards the mating material. However, in this test, the composite material (H) with a volume fraction of aluminum borate whiskers of 30% also
It can be seen that, compared to the presently invented materials (A) to (E), both volume fraction and aggressiveness similarly exhibit slightly better characteristics. However, when abrasion test II was conducted under more severe conditions, as shown in FIG. 3, abnormal abrasion occurred in the (H) sample, and the amount of abrasion became extremely large. Samples (A) to (E), which are materials of the present invention, exhibited good abrasion resistance even under the severe conditions of abrasion test II. However, (E
) Looking at the results of the abrasion test II of the sample, the amount of wear has increased slightly, and in order for the wear resistance under severe conditions to be at the current material level (J), the volume ratio of the alumina short fiber itself must be increased. The lower limit is considered to be 5%. Also, considering the coefficient of thermal expansion, as shown in Table 2 and Figure 4, the total (
This shows that sample (H) when the volume fraction Vf of TOTAL) is 25% is at the upper limit of the cast iron level of 13.4/106 °C, and the lower limit of aluminum borate whiskers is 5%. .

Therefore, in order to obtain the target properties and to uniformly disperse the reinforcing material in the composite material, as shown in FIG. It is necessary to keep

This means that the total (TOT) of the hybrid molded product of aluminum borate whiskers and short alumina fibers is
When the volume fraction of AL) is in the range of 25 to 30%, the mutual volume fraction ratio of aluminum borate whiskers/alumina short fibers is
A range of 0.5 to 2.0 indicates that excellent characteristics such as good wear characteristics and a low coefficient of thermal expansion can be obtained.

Further, from Table 2, it is found that the thermal expansion coefficient can be made smaller as the volume fraction of the alumina short fibers decreases, and the same volume fraction ratio can be selected from a wide range of 0.5 to 2.0. It is possible.

[0043] Among the comparative materials, aluminum composite material sample (K) (composite material of SiC whiskers and aluminum alloy: SiC volume fraction Vf = 30%), which has been announced as a vane material for rotary compressors, and the present invention material When compared, (K) has a very large amount of wear and a large amount of attack on the mating material, indicating that the material of the present invention is superior.

As described above, when the first sliding member is formed by impregnating the hybrid molded product formed by mixing aluminum borate whiskers and short alumina fibers with an aluminum alloy to form a composite, the first sliding member itself becomes As a result, it is possible to rationally combine the respective advantages of the short alumina fibers and aluminum borate whiskers to obtain an aluminum composite material that is less aggressive to the mating material and exhibits good wear resistance even under severe sliding conditions. can. Furthermore, the coefficient of thermal expansion can be further lowered than in the case of only short alumina fibers, and the bending strength can be increased than in the case of only aluminum borate whiskers. As a result, it becomes optimal as a vane or rotor for a rotary compressor.

Furthermore, the blending ratio of alumina short fibers and aluminum borate whiskers can be varied widely, and both reinforcing materials effectively contribute to improving wear resistance and reducing the coefficient of thermal expansion. Therefore, in order to obtain a composite material with good characteristics depending on the application, the range of the above-mentioned compounding ratio can be set broadly, and the ratio can be relatively freely selected according to the required characteristics in relation to the mating member. Become.

However, on the other hand, the second sliding member, which is the sliding member in sliding contact with the first sliding member, is made of, for example, a conventional general cast iron-based material (for example, SKH-51 cast iron or monochromatic cast iron). However, the mass is still large, and it cannot be said that it is necessarily capable of sufficiently supporting high-speed operation. Therefore, in this embodiment, the second sliding member used in combination with the first sliding member described above is
The sliding member is made of a cast iron material that is made lighter by about 50% to 70% by drilling holes in the existing cast iron material.

The rotor and vane combination of current rotary compressors is usually a combination of SKH-51 cast iron and monochrome cast iron. Therefore, considering the above-mentioned combination of the first sliding member and the second sliding member on this premise, the combination (a) of the lightweight SKH-51 cast iron with holes and the aluminum composite material , a combination of the above aluminum composite material and monochromatic cast iron that has been made lighter by drilling holes (
There are two possible samples: b).

Therefore, now these two combinations (a), (
Test pieces similar to those described above were manufactured in step b), and a wear test was conducted using the pin-on-disc friction and wear tester shown in FIG. As a comparative example, for example, a combination (c
), a combination (d) of the above aluminum composite material (of the first sliding member mentioned above), a combination (e) of an aluminum alloy and the above aluminum composite material (of the first sliding member mentioned above) ,
Combination of aluminum alloy and SiC whisker-reinforced aluminum composite material (f); Combination of lightweight monochromatic cast iron made by drilling and SiC whisker-reinforced aluminum composite material (g)
, six types of combinations (h) of conventional general SKH-51 cast iron and monochromatic cast iron were employed, and the wear volumes were measured in the same manner. The wear test was carried out at a sliding speed of 1 m/sec.
c. Measure the wear volume of each pin test piece (numbers 3a, 3b, 3c in Figure 1) and the second disk (number 2 in Figure 1) after 7 hours of operation under the condition of a surface pressure of 645 kgf/cm2. did.

As a result, the results of the wear test were as shown in the graph of FIG. As is clear from the measurement data, both the two combinations (a) and (b) of the first and second sliding members of the present invention have a small amount of wear, and the conventional combination of cast iron (h) However, other material combinations (c) to (g) all exhibited pin cracking and seizure phenomena. Therefore, the two combinations (a) of both the first and second sliding members of the present invention described above.
, (b) has the highest wear resistance and is clearly a combination that allows weight reduction. As a result, the combination structure of the sliding members of the present invention can sufficiently cope with the increase in speed of the rotary compressor.

[0050] The above-mentioned problem in the prior art can be solved in still another embodiment, for example, in a combination structure of two sliding members, a first and a second sliding member that abut each other and slide relative to each other. While the sliding member 1 is made of a carbon member impregnated with aluminum with holes drilled,
The second sliding member has a total volume ratio of 2 in the entire sliding member.
Si in the entire aluminum alloy is added to the hybrid molded body of aluminum borate whiskers and alumina short fibers with a ratio of 5 to 30% and a total volume fraction in the entire sliding member of 0.5 to 2.0. The problem can also be effectively solved by using in combination a pair of sliding members made of an aluminum composite material made by impregnating and solidifying an aluminum alloy with a content of 20 to 30%.

[0051] The first sliding member is formed by further reducing the weight of a carbon member impregnated with aluminum by drilling.In addition to the lightness obtained from the characteristics of the carbon and aluminum materials themselves, By doing so, the weight is significantly reduced. Moreover,
However, it has a small coefficient of thermal expansion and relatively excellent wear resistance. In addition, the volume percentage of the entire sliding member is 25 to 30%.
, and the Si content in the whole aluminum alloy is 20 to 20 in the hybrid molded body of aluminum borate whiskers and alumina short fibers with the same volume fraction ratio in the range of 0.5 to 2.0.
The second sliding member made of an aluminum composite material impregnated and solidified with 30% aluminum alloy is lightweight in terms of mass, and has a small coefficient of thermal expansion and high wear resistance.

Therefore, the relative sliding member formed by such a combination of the first and second sliding members can also withstand sufficiently high speed rotation, and the amount of wear can be reduced. It will also be smaller.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the configuration of a friction and wear tester in a combination structure of sliding members according to an embodiment of the present invention.

FIG. 2 is a graph showing the results of a first wear test of the first sliding member in the same example.

FIG. 3 is a graph showing the results of a second wear test of the first sliding member in the same example.

FIG. 4 is a graph showing measurement data of the coefficient of thermal expansion of the first sliding member in the same example.

FIG. 5 is a graph showing the relationship between the blending ratio of aluminum borate whiskers and short alumina fibers in the first sliding member of the same example.

FIG. 6 is a graph showing the results of a wear test on the combination of the first sliding member and the second sliding member in the same example, in comparison with a comparative example.

Claims (3)

[Claims] [Claim 1] A first member that abuts each other and slides relatively.
and a second two sliding members, wherein the first sliding member is made of an aluminum composite material in which a hybrid molded body of aluminum borate whiskers and alumina short fibers is impregnated with an aluminum alloy; A combination structure of sliding members, characterized in that the sliding members are made of cast iron material that has been made lightweight by drilling. 2. The total volume fraction of the hybrid molded body of aluminum borate whiskers and short alumina fibers in the first sliding member is 25 to 30% of the entire sliding member,
2. The combination structure of sliding members according to claim 1, wherein the blending ratio of aluminum borate whiskers and short alumina fibers in the molded body is 0.5 to 2.0. 3. The sliding device according to claim 1 or 2, wherein the aluminum alloy impregnated into the hybrid molded body of aluminum borate whiskers and short alumina fibers contains 20 to 30% of Si component. A combination structure of members.