JPS6213418B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a sliding material mainly composed of copper, and particularly to a sliding material suitable as a material for sliding members exposed to severe sliding conditions. Conventional technologies and problems As sliding materials mainly made of copper, phosphor bronze,
High-strength brass is generally known and is said to have excellent sliding properties. However, it cannot be said to be a sufficient material for impulse members that are exposed to extremely severe sliding conditions, such as being used under high loads and high temperatures with almost no lubrication. A typical sliding member used under such severe conditions is a swash plate compressor. As shown in FIG. 1, a swash plate type compressor generally includes a piston 23 moored to a swash plate 25 so as to straddle it, and the reciprocating motion of the piston 23 as the swash plate 25 rotates moves refrigerant gas into cylinder bores. 22 and compresses it. Swash plate 25
is fixed to a shaft 24 rotatably supported by a cylinder block 21, and a piston 23 is moored to a swash plate 25 via a shoe 26 and a ball 27. When the shaft 24 and the swash plate 25 are rotated together, the shoe 26 slides on the sliding surface of the swash plate 25 and transfers the axial movement of the outer circumference of the swash plate 25 to the piston 23 via the ball 27.
It is communicated to. The refrigerant gas compressed by this swash plate compressor is liquefied in a condenser, evaporated in an evaporator, removes latent heat of vaporization from the surroundings, cools the indoor air, and is then sucked into the swash plate compressor again. repeat. When such a swash plate compressor is used for a car cooler, the operating conditions are extremely severe. This is because the drive source is an internal combustion engine such as gasoline or diesel, and the compressor is designed to have a rotational speed almost the same as that of the internal combustion engine in order to reduce the size and weight of the compressor and the compressor capacity. Therefore, the rotation speed of the swash plate compressor is approximately the same as the idling speed of the internal combustion engine.
Approximately from 500 rpm when driving at high speed or when accelerating suddenly.
It will change over a wide range up to 6000 rpm. Additionally, although this problem is not limited to swash plate type compressors, as vehicles have become lighter in recent years, there has been a demand for compressors themselves to be smaller and lighter.
The oil pump inside the compressor has been removed, and in addition to this, the amount of lubricating oil has been reduced in order to improve its performance, making it easier for friction and wear to occur on the sliding parts inside the compressor. There is. Furthermore, it cannot be overlooked that the high temperature in the engine room due to the installation of various devices installed in the engine room in recent years, such as exhaust gas control devices and devices to reduce fuel consumption, has an adverse effect on the lubricating oil in the compressor. It's summery. In a swash plate type compressor used under these conditions, the portion exposed to the most severe sliding conditions is the sliding portion between the swash plate 25 and shoe 26 shown in FIG. The sliding speed is approximately 2 to 3 m/sec when the engine is idling, and at approximately 6000 rpm at maximum rotation.
20~25m/sec, about 7~ even during normal driving
This is because the speed is 15m/sec. In addition to such high-speed sliding, a high load is applied to the shoe to compress the refrigerant gas, and the size of the load is
It is 60-130Kg/ ^cm2 . Although it is rare for such a combination of sliding speed and pressure to be the maximum, the PV value when pressure is PKg/cm ² and speed is Vm/sec often exceeds 2000. Possible. Moreover, the load that the shoe receives becomes an impact load especially at high rotation speeds, and the sliding part between the swash plate and the shoe is subject to extremely harsh sliding conditions of receiving such impact load and sliding at high speed. will occur. Also, when looking at the sliding conditions between the swash plate and shoe from the lubrication perspective, with the removal of the oil pump as described above,
Only a small amount of lubricating oil is supplied to the sliding parts. This is because, in a swash plate type compressor in which the oil pump has been removed, refrigerant gas containing a mist of lubricating oil is generally used to lubricate each sliding part within the compressor. This is because the amount of lubricating oil and the cooling capacity are inversely proportional, so reducing the amount of oil is an effective means of increasing the cooling capacity of the swash plate compressor. From another perspective, this means that the lubrication conditions have the greatest effect on the life of the sliding parts of the swash plate and shoe.
Therefore, among these conflicting relationships, the materials of the swash plate and shoe are particularly taken into consideration when designing a swash plate type compressor. Furthermore, the sliding motion between the swash plate and shoe is a thrust sliding motion in which it is difficult to obtain a sufficient lubrication effect even if sufficient oil is supplied, so the sliding surfaces are always under boundary lubrication. , or there is solid contact there.Also, as a phenomenon that occurs because the swash plate type compressor for a car cooler performs unsteady rotational movement that is inevitable in its use, there is a phenomenon that occurs on the sliding surface between the swash plate and the shoe. Lubricating oil is not supplied for several tens of seconds or even several minutes after startup, so during this time the swash plate and shoe are left almost unlubricated and operated in solid contact. . This situation can occur when refrigerant leaks from the pipes and the amount of refrigerant contained in the refrigeration cycle becomes low, or when refrigerant gas is returned to the compressor due to the operation of the evaporation pressure regulating device attached to the evaporator. This is also caused when the amount is decreased. Therefore, of the various troubles that have arisen in conventional swash plate type compressors, the most common cause is the seizure that occurs without lubrication from the time of startup, and the wear that occurs without lubrication is also the cause. After that, burn-in occurred. Traditionally, swash plates have been made of structural materials that have mechanical rigidity, fatigue strength, and wear resistance, as materials that can withstand the lubrication conditions described above, as well as materials that can withstand high surface pressure and impact loads as described above. Alloy steels such as nickel chrome steel, nickel molybdenum steel, chrome molybdenum steel, and spheroidal graphite cast iron were used, and the surface layer was hardened. In addition, the ball is mainly used to withstand high loads.
After all, something like high carbon chromium steel was used. In addition to the above-mentioned phosphor bronze and high-strength brass, the shoe materials have been considered to include arzyl alloys, copper-lead-tin alloys, brass, bronze, aluminum bronze, Babitt metal, oil-impregnated bearing alloys, and the like. However, none of the materials known so far have been satisfactory for the extremely severe operating conditions unique to swash plate type compressors for car coolers. There has been a desire to develop a sliding material with a longer lifespan that has better properties than conventional ones, such as excellent wear resistance. Means for Solving the Problems In view of the above circumstances, the present inventors conducted various research and development and found that repeated operation at a sliding speed of 2 to 25 m/sec and surface pressure of 130 to 140 Kg/cm ² were performed. We have discovered an excellent sliding material that can withstand use as a shoe material that is exposed to extremely harsh conditions such as repeated impact loads, a small supply of lubricating oil, and no lubrication for tens of seconds to several minutes after startup, and have developed the present invention. This is what we have come to complete. That is, the present invention provides a sliding material that is strengthened to the extent that thermal conductivity is not significantly reduced, has little decrease in hardness especially at high temperatures, and has good sliding properties. The main point is copper (Cu), and
1% in total amount of 8% manganese (Mn), 0.1 to 4% silicon (Si), and one or more elements selected from the group consisting of Group A elements and Group A elements of the Periodic Table of Elements. and phosphorus (P) in an amount not exceeding 1%, and 0.5 to 15
% of lead (Pb) and/or less than 5% of tin (Sn). Mn and Si used in the present invention are
It is an additive element that mainly forms a solid solution in Cu to improve its mechanical strength, and group a and group a elements are elements that mainly precipitate within the Cu base material to strengthen it. Hereinafter, the group of elements that form a solid solution in Cu and have a strengthening effect will be referred to as the Group A, and the group of elements that will precipitate in the Cu base material and have a strengthening effect will be referred to as the Group O. We aim to effectively strengthen the Cu base material with both elements from group A and group O.
This effectively improves wear resistance and seizure resistance. In addition, the present invention adds Pb and/or Sn (both of which improve sliding properties) as elements to be added to the Cu base material together with elements of Group A and Group B to improve sliding properties. (hereinafter referred to as group C for convenience) and P. In sliding parts where the amount of lubricating oil is small, the most important issue is the thermal conductivity of the sliding member, and what has the greatest effect on that thermal conductivity is the added element, and the amount of heat generated is determined by the coefficient of friction. Therefore, how to strengthen the base material and improve conformability with as few additive elements as possible is an important point in obtaining an excellent sliding material. In addition, during normal operation of a swash plate type compressor, a certain amount of lubricating oil is supplied, although it is relatively small, so rather than emphasizing compatibility as a shoe material, it is important to have good thermal conductivity and to effectively dissipate heat. It is effective to reduce the decrease in hardness and to reduce the change in structure under high temperature conditions in order to improve the sliding performance of shoes. In this sense, it is particularly effective to use the morphemes of group A and the elements of group O in combination. In addition to strengthening the base material and improving its wear resistance through solid solution, too much solid solution elements can cause harm due to intermetallic compounds, resulting in uneven structure and reduced thermal conductivity, as well as excessive hardening of the base material. In order to prevent embrittlement caused by this, it is effective to use precipitation-type additive elements that can strengthen the base material without causing much of the harm described above. It is possible to obtain dynamic materials. In addition, Sn used in combination with elements of group A and group O
Pb also has a good effect in the same sense, but Pb, which is a low melting point material added mainly for the purpose of improving conformability, does not have a very noticeable effect during normal operation. However, on the other hand, when the engine is operated in conditions that are closer to no lubrication than at the time of startup, the effect of improving conformability using the low melting point material Pb is greatly demonstrated. Furthermore, P, which is added to the Cu base material together with the elements of Group A, Group O, and Group C, effectively strengthens the Cu base material as an extreme pressure additive element, maintains its hardness at high temperatures, and maintains the hardness of the Cu base material. When used in combination with Pb and/or Sn, which are elements in the group, the coefficient of friction is lowered, greatly contributing to improving conformability and sliding properties. In addition, when used in combination with Mn, which is an element of Group A, fine precipitated phosphides are formed, effectively strengthening the Cu base material. It should be noted that normally, when selecting a sliding member, the selection of a mating member is also important, and when the conditions are especially severe, the mating member is also more limited. Under such circumstances, the material of the swash plate, which is the mating member, is Cr in conventional sew materials.
Steel, Mn steel, etc. are relatively good, but spheroidal graphite cast iron has poor sliding properties and is not suitable as a mating material. However, it has been confirmed that the shoe made of the sliding material according to the present invention can withstand even when the swash plate is made of spheroidal graphite cast iron. Additionally, according to the inventors' study, it is desirable that the hardness of the sliding material used for the swash of a swash plate type compressor for a high-performance car cooler is 80 or more in terms of Vickers hardness (Hv) at a high temperature of 300°C. However, all of the sliding materials according to the present invention have such desirable hardness, and thus exhibit excellent effects. Here, according to the present invention, Mn and Si are added as solid solution type additive elements which are Group A elements added to Cu, and chromium (Cr) and titanium (Ti) as precipitation type additive elements which are Group B elements are added to Cu. The amounts of each of Group A and Group A elements, such as zirconium (Zr), to be added are determined in consideration of the following. That is, first, Si is 0.1 to 4%, preferably 0.3 to 2%.
Used in a range of %. If it is less than 0.1%, the solid solution amount is insufficient as a solid solution strengthening element for the Cu base material, and if it is less than 4%
This is because if added in an amount exceeding this amount, intermetallic compounds will precipitate and the alloy will become brittle. Also, Mn is 1~
It is necessary to add it at a rate of 8%, preferably 1.5-5%, and 2-4% is best. In the present invention, Si and Mn are used together. Although Mn alone can improve mechanical properties through solid solution,
This is because when this is added together with Si, the most ideal eutectic silicide can be obtained and excellent wear resistance can be obtained. However, if the amount of Mn added is less than 1%, it becomes a hypoeutectic silicide, and sufficient wear resistance cannot be obtained.On the other hand, if it exceeds 8%, the hardness of the base material becomes too high, causing wear of the mating member. This is because, at the same time, the thermal conductivity decreases too much. Furthermore, among the Group A elements, which are Group B elements, the most preferably used elements are Cr, Ti,
It is one type or a combination of two or more types of Zr, and the addition of Cr can cause precipitation hardening and increase the strength of the alloy. However, since excessive addition of Cr makes the entire alloy brittle, the appropriate blending ratio of Cr is 1% or less. Furthermore, Ti acts to strengthen the alloy through heat treatment, and its precipitation can increase the hardness of the alloy. The appropriate blending ratio of Ti required to improve the strength during precipitation hardening is 1% or less. Furthermore, Zr can form intermetallic compounds with other alloying elements to strengthen the alloy, and such intermetallic strengthening can be achieved by introducing the elements separately in equal amounts into the composition of the intermetallic compound. It is even more effective than
However, if the amount of Zr added exceeds 1%, it causes a rapid decrease in thermal conductivity, so in the present invention,
The amount of Zr added will be appropriately determined within a range not exceeding 1%. By the way, these examples do not mean that the group B elements according to the present invention are limited to the above three types, and molybdenum, tungsten, etc. can be similarly used, and two or more of the group B elements can be used. When used, the total amount should be within 1%. This is because adding more than 1% of the total amount causes problems such as embrittlement of the entire alloy. In addition, it is difficult to set a lower limit on the amount of addition, as even a small amount of these group B elements can have some effect, but in general, it is difficult to set a lower limit for the addition amount of group B elements alone or in combination of two or more. Even when the group elements are added, the amount is about 0.1% (total amount), which can sufficiently improve mechanical strength. In addition,
The preferred addition range of these Group B elements is 0.2 to 0.8%.
It is. Furthermore, in the present invention, Pb, which is one of the C group elements that is suitably added to the Cu base material along with the A group elements and the O group elements, is a low melting point material (melting point of 400°C or less) that does not dissolve in the Cu base material. By adding such Pb or a Pb alloy mainly composed of Pb, which is a low-melting point material, the sliding properties of the shoe, especially the conformability and sliding properties, are significantly improved. With this effect, various troubles caused by sliding of the shoe under no lubrication during startup and under boundary lubrication during operation, which are particular to high-performance swash plate type compressors, can be more effectively resolved. It happens. In order to fully exhibit the effect of adding Pb, it is necessary to add it in an amount of 0.5 to 15%, preferably 5 to 10%, and if the amount added is less than 0.5%, the desired compatibility may not be achieved. is not obtained and 15
If it exceeds %, it is difficult to uniformly disperse it in the alloy, necessitating the use of a special manufacturing method, and ultimately reducing the strength of the base material, which is not preferable. Furthermore, together with or in place of the above Pb, it may be used in combination with group A elements and group O elements.
Sn has the same effect as Pb in terms of improving sliding properties such as slipperiness and suppressing seizure, and of course strengthens the base material by being dissolved in Cu. In terms of sliding properties, the friction coefficient is low, and this friction coefficient is stable even at high temperatures.As a result, it has an excellent effect on improving seizure resistance especially under high temperature conditions. It shows itself. However, since Sn dissolves in Cu as described above, it tends to reduce the thermal conductivity of the resulting alloy, and therefore the range of its addition is limited. In this sense, 5% is adopted as the upper limit of Sn addition, and the amount of Sn added is determined as appropriate within the range of less than 5% (of course, 0 is not included), preferably within the range of 1 to 3%. The Rukoto. Furthermore, this Sn
The addition of is also effective in improving castability. P, which is added in addition to the elements of Group A, Group O, and Group C, must be used in an amount not exceeding 1%, thereby effectively strengthening the Cu base material and This effectively suppresses the decrease in hardness at the bottom. Although the addition of P will reduce the thermal conductivity of the alloy to some extent, this will be reduced due to other effects of P itself and synergistic effects with other additive elements. The problem is well covered. In other words, by adding P, in addition to maintaining the hardness at high temperatures mentioned above, when combined with Pb and/or Sn, which are group C elements, the coefficient of friction is reduced, thereby improving conformability and sliding properties. The sliding properties, especially under high loads, are significantly improved, and the presence of fine phosphides formed in the base material makes it easier to capture lubricating oil, thereby preventing oil film and oil depletion. This makes it less likely to be triggered. In addition, if the amount of P added exceeds 1%, the entire alloy becomes too hard and brittle, making it easy to break and making it unsuitable for use as a sliding material such as shoes that are subject to high impact loads. In addition, problems such as an extreme decrease in the thermal conductivity of the alloy arise. In addition, P in the present invention
The lower limit of the amount of P added is based on the fact that adding even a small amount of P will produce a certain degree of effect commensurate with that amount.
It is extremely difficult to limit it uniquely. For example, even when added in an amount of about 0.01 to 0.03%, the deoxidizing effect of P itself improves the thermal conductivity of the alloy, and it is possible to prevent seizure from this side. Furthermore, the addition of P is also effective in improving castability. Effects of the Invention The Cu alloy sliding material according to the present invention has the following effects. First, compared to conventional shoe materials, the amount of added elements is significantly smaller and the lubricating oil trapping performance and sliding performance are excellent, so even if the near-unlubricated state continues for a long time, significant generation of frictional heat is suppressed, and Even at high temperatures, the material does not soften, making it difficult to seize. In addition, in the case of the present invention, there are fewer additive elements for strengthening compared to the conventional materials, so it seems that sufficient strengthening is not achieved compared to the conventional materials, but in the case of the conventional materials, the additive elements The copper alloy of the present invention is better than the copper alloy of the present invention because it was intended to compensate for the ease of seizure caused by poor heat dissipation due to a large amount of Pb of 20 to 40%. Although it is somewhat better at room temperature,
In contrast, the present invention has fewer additive elements for reinforcement, but it also contains fewer additive elements for improving conformability, resulting in a lower strength than conventional materials. There is no difference. Furthermore, especially at high temperatures, the copper alloy of the present invention exhibits superior strength to conventional materials. Furthermore, in the present invention, the number of additive elements to improve conformability is small, and the addition of solid solution elements such as Mn, Si, Sn, and P, which reduce hardness even at high temperatures, makes it possible to improve the sliding properties of shoes, etc. Even if the moving parts become hot due to frictional heat, their strength and hardness do not decrease and they remain in an extremely stable state.As a result, the conformability improvement effect of evenly dispersed Pb, etc., becomes even more effective. It will be demonstrated. The Cu alloy of the present invention also contains nickel (Ni), iron (Fe), tellurium (Te) as other additive elements.
Antimony (Sb), arsenic (As), etc. can be added in small proportions, and this has the effect of mainly improving strength or making the matrix finer. However, each addition has advantages and disadvantages; Si, Cr,
It has been confirmed that the performance is slightly lower than that of Zr, Ti, Pb, and Sn. However, it has been confirmed that it can withstand use under certain conditions. As is clear from the above explanation, the sliding material according to the present invention was developed for use in swash plate type compressor sashes where the sliding conditions are extremely severe.
It is used as a material for sliding parts such as bushes for sliding bearings and thrust washers, where the sliding conditions such as the amount of lubricating oil and load are not as severe as those for shoes. Of course, it is also possible to do so, and excellent effects can also be obtained in this case. Examples Specific examples of the present invention will be shown below to further facilitate understanding of the present invention. First, samples 1 to 8 were obtained by a casting method using the composition ratios shown in Table 1. As a casting method, at approximately 1250℃
Cu, alloying elements (Mn, Si, Sn, Cr, Zr, Ti,
A method was adopted in which P) and Pb were added in this order, and the resulting material was heat treated at approximately 700°C for 2 hours to prevent segregation, to obtain a Cu alloy material. In order to conduct actual machine tests using these obtained materials, each was processed to a diameter of 18 mm and a thickness of 4.5 mm to obtain a shoe. In addition, a spherical concave surface with a depth of about 3 mm was formed in the shoe so that a part of a ball with a diameter of about 14 mm was inscribed in the center. As comparative samples, Samples 9 to 19 having the alloy compositions shown in Table 2 were prepared by the same method as above, and samples 9 to 19 according to the present invention were prepared.
A comparison was made with that obtained from Cu alloys. In addition, the hardness of Samples 1 to 8 at the time of final processing at room temperature was all Hv100 or more.

【table】

【table】

【table】

[Table] - Experiment 1 - Using each sample in Tables 1 and 2, an experiment was conducted to measure the coefficient of friction and the temperature at which the heat was generated. The measurement method was to rotate a disc, press a shoe against it, and gradually increase the pressing load while measuring the coefficient of friction and the heat generation temperature of the shoe. Conditions (1) Sliding speed constant 13m/sec (2) Load 4.0Kg/cm ² Gradually increased by 20Kg/cm ² Each load step is 30 minutes (3) Lubricating oil Low viscosity oil SSU70 (4) Lubrication method Felt application Approx. 0.8cc/min (5) Test piece disk: Straightness 1 μm or less, roughness (maximum) 0.4 to 0.6-S Shade: Straightness 1 μm or less, roughness (maximum) 0.4 to 0.6-S The obtained results are shown in Figure 2. It is shown in Figure 3. As is clear from FIG. 2, the sample based on the present invention has a lower coefficient of friction in all regions than the comparative sample.
And it is stable even in high load areas. Also, looking at the heat generation temperature of the shoe from Figure 3,
In the case of the sample according to the present invention, compared to the comparative sample,
It is particularly low in high load areas. Comparative samples 15, 16, and 17, which have poor thermal conductivity, generate more heat when the load is increased, and this heat generation changes the structure of the material, causing a tendency to seize due to an increase in the coefficient of friction. However, the sliding properties of the present invention sample are significantly improved due to the synergistic effect of the addition of Group A, Group O, Group C elements and P, so the temperature of the entire shoe or the sliding surface The nearby temperature does not get too high, so there are few phenomena such as changes in structure or increases in the coefficient of friction, and it is stable in all areas. What is particularly noteworthy here is that even though the lubricating oil was not sufficient, the samples of the present invention performed well, and this is of great significance. - Experiment 2 - Next, we varied the supply amount of lubricating oil below 150c.c., and conducted an actual machine test under the most severe conditions for the supply, and the results obtained are shown in Table 3. The test conditions are as follows. (1) Compressor Swash plate type compressor (total displacement 150c.c.) (2) Number of rotations 4000rpm (3) Discharge side gas pressure Pd = 4 to 5Kg/cm ² (4) Suction side gas pressure Ps = approx. -50mmHg (5) Operating time 20Hrs (6) Lubricating oil Refrigerator oil 110~150c.c. (7) Compatible material Spheroidal graphite cast iron (8) Gas amount 100g (approx. 10% of regular)

【table】

[Table] ○: No abnormality △: Partial seizure ×: Seizure As is clear from Table 3, the amount of lubricating oil was significantly reduced in the samples according to the present invention compared to other comparative samples. This effectively prevents the occurrence of burn-in. In particular, since this experiment was performed under the most severe lubrication conditions that occur under normal operating conditions, the fact that it can be used even under such conditions is proof of the superiority of the Cu alloy sliding material according to the present invention. It is. -Experiment 3- Next, under the same conditions as in Experiment 1, experiments were conducted five times on the shoes obtained from each sample, and variations in the seizure load were examined to evaluate the uniformity of the material. The obtained results are shown in FIG. 4, and as is clear from this figure, samples 2, 3, 5, and 7 according to the present invention
Each shoe obtained from
Moreover, since there was little variation in the load that led to seizure, it was confirmed that the quality was extremely uniform.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view for explaining the swash plate type compressor, and Figs. 2 and 3 are graphs showing the friction coefficient and heat generation temperature results obtained in experiments to investigate the effects of the present invention. be.
Moreover, FIG. 4 is a graph showing the variation in seizure load of each sample obtained in another experiment. 21...Cylinder block, 22...Cylinder bore, 23...Piston, 24...Shaft, 25...Swash plate, 26...Show, 27...Ball.

Claims (1)

[Claims] 1 Mainly copper, with 1 to 8% manganese, 0.1 to 4% silicon, and element a of the periodic table.
Contains one or more elements selected from the group consisting of group elements and group a elements in a total amount not exceeding 1% and phosphorus in an amount not exceeding 1%, and 0.5 to 15% A sliding material characterized by containing less than 5% of lead and/or less than 5% of tin.