JP2017101584A - Method for molding sliding surface of cylinder block and cylinder block - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for molding a sliding surface of a cylinder block and a cylinder block capable of molding a sliding surface of a cylinder bore easily and in a less-expensive manner and further realizing a superior sliding performance.SOLUTION: This invention comprises a compressing and charging step for compressing powders 44 containing copper alloys 41 and high-sliding characteristic additive elements 42 in a cylinder bore 5 and forming the compressed powder molded body closely adhered to an inner cylindrical surface of the cylinder bore 5 and a sintering step for sintering the compressed powder molded body formed at the compression charging step. At the compression and charging step, the high-sliding characteristic additive elements 42 are dispersed at the compressed powder molded body in such a way that concentration of the high sliding characteristic additive elements 42 contained in the compressed powder molded body is made different in at least one of axial direction and around the axis of the cylinder bore 5.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a cylinder block sliding surface forming method and a cylinder block for forming a cylinder block sliding surface in a hydraulic rotary machine such as a hydraulic pump or a hydraulic motor.

  In general, hydraulic drive devices such as hydraulic pumps and hydraulic motors typified by hydraulic pumps are composed of many sliding parts, and the sliding surface is broken by a lubricating oil film due to high sliding surface pressure. Since there is a risk of seizure of sliding surfaces and local abnormal wear due to the effect of instability of the sliding contact state due to fluctuations in control oil pressure, etc., the material of these sliding parts As steel materials are mainly used.

  Therefore, the cylinder bore and piston of the cylinder block, which is a typical component of hydraulic drive equipment such as a hydraulic rotating machine, are formed of steel material. In particular, the cylinder bore is worn by sliding with the piston that is the sliding counterpart. In order to suppress the occurrence of these wear and seizure phenomena, various surface treatments such as surface modification and surface processing are performed on the sliding surfaces of the cylinder bore and the piston. .

  As one of the conventional techniques for such surface treatment, a cylindrical molded body of a copper-based material, that is, a copper alloy liner is bonded to the inside of a cylinder bore of a cylinder block made of an iron-based material by sintering, and the density after this bonding As a conventional technique, a sintered bonded cylinder block in which the density of the cylinder is made higher than that of the cylindrical molded body before sintering has been proposed (see, for example, Patent Document 1).

  This prior art sintered bonded cylinder block avoids sticking of both sliding surfaces due to seizure of the piston and cylinder bore by a copper alloy liner sintered inside the cylinder bore, but this copper alloy liner is made of lead bronze. In general, the lead content is 10% or more, which is not preferable in view of environmental influences.

  In particular, the trend of reducing the use of environmentally hazardous substances, such as the RoHS directive for electrical and electronic products and the ELV directive for discarded vehicles, is currently leading to a reduction in lead-containing copper alloys. It is necessary to develop a cylinder block that exhibits sliding performance equivalent to or higher than that of the prior art while reducing the rate to 4% or less.

  Here, as one of the prior arts useful for the development of a cylinder block with a reduced lead content of a copper alloy, bismuth, nickel, and sulfur are contained in a predetermined ratio in a bronze alloy mainly composed of copper and tin, respectively. As described above, by adding bismuth, nickel, and sulfur to copper and tin, the fine copper tin-based intermetallic compound is precipitated in α-copper, and the metal fine particles containing bismuth A method for producing a bronze alloy in which a co-deposited phase that has been dispersed and precipitated is known (see, for example, Patent Document 2).

  The bronze alloy produced by this prior art bronze alloy production method has excellent wear-friction characteristics and seizure resistance due to the micro-laminated structure of copper-tin intermetallic compound and the eutectoid phase of metal fine particles such as bismuth. It can be used as a sliding member. Therefore, if a copper alloy liner is formed using a special bronze alloy manufactured by the above-described prior art bronze alloy manufacturing method and this copper alloy liner is applied to the sliding surface of the cylinder bore, the lead content can be suppressed. However, it seems that the occurrence of wear and seizure on the sliding surface of the cylinder bore can be suppressed.

JP-A-10-196552 JP 2010-31347 A

  However, the conventional method for producing a bronze alloy disclosed in Patent Document 2 controls copper tin by controlling the eutectoid transformation that proceeds in two stages in a predetermined temperature range with additive elements of bismuth, nickel, and sulfur. It is designed to deposit a fine layered structure of intermetallic compounds and a eutectoid phase of fine metal particles such as bismuth, so when producing a special bronze alloy, these fine layered structure and eutectoid phase are deposited. The cooling temperature condition to be made becomes very strict, and it is a problem that manufacturing management is difficult. Therefore, the bronze alloy manufactured by the prior art bronze alloy manufacturing method is not suitable as a sliding member applied to the sliding surface of the cylinder bore of the cylinder block.

  In addition, as described above, the conventional bronze alloy manufacturing method uses bismuth as an essential additive element to disperse and precipitate the eutectoid phase of metal fine particles such as bismuth, but this bismuth is a rare metal. When the price is high and it is used as a substitute for lead, there is a concern that the manufacturing cost will increase significantly. Therefore, even when bismuth is used in this way, it is desirable that the addition amount of bismuth be as small as possible, but bismuth is necessary to reduce the eutectoid transformation temperature by dispersion and precipitation as described above. In addition, since it is an element that improves pressure resistance, reducing the amount of bismuth added may reduce sliding performance such as wear friction characteristics and seizure resistance of the sliding member.

  The present invention has been made in view of the actual situation of the prior art as described above, and its purpose is to provide a cylinder block capable of easily and inexpensively molding the sliding surface of the cylinder bore and exhibiting excellent sliding performance. And a cylinder block.

  In order to achieve the above object, a method of forming a sliding surface of a cylinder block according to the present invention includes a rotating shaft, a cylinder block that rotates around a central axis as the rotating shaft rotates, and a cylinder bore of the cylinder block. A cylinder block sliding surface molding method for performing a surface treatment on a cylindrical surface inside a cylinder bore of a hydraulic rotating machine including a piston accommodated in a cylinder block, and forming a sliding surface of the cylinder bore, A compression filling step of compressing and filling a powder containing an alloy and an additive element having high slidability into the cylinder bore, and forming a compact formed in close contact with the cylindrical surface inside the cylinder bore; and the compression filling step A sintering step of sintering the green compact formed by the step of compressing and filling, wherein the concentration of the highly slidable additive element contained in the green compact is the cylinder Axial and differently at least one direction around the axis of the is characterized by having dispersed therein the additional element of the high slidability in the green compact.

  Further, the cylinder block of the present invention is provided in a hydraulic rotating machine including a rotating shaft, a cylinder bore arranged around the rotating shaft, and a piston accommodated in the cylinder bore, and a cylinder inside the cylinder bore is provided. A cylinder block including a sliding surface with respect to the piston formed on a surface, the sliding surface including a copper alloy and an additive element having high slidability, the axial direction of the cylinder bore and around the axis At least one of the above is characterized by comprising coating layers having different concentrations of the highly slidable additive element.

  According to the cylinder block sliding surface molding method and the cylinder block of the present invention, the cylinder sliding surface can be molded easily and inexpensively, and excellent sliding performance can be exhibited. Problems, configurations, and effects other than those described above will become apparent from the following description of embodiments.

1 is a schematic cross-sectional view of a variable displacement swash plate type axial piston pump to which a cylinder block sliding surface molding method according to a first embodiment of the present invention is applied. It is a figure explaining the operation | movement relationship of the cylinder block shown in FIG. 1, a piston, and a valve plate. It is a figure explaining the sliding state of the cylinder bore and piston shown in FIG. It is a figure explaining the compression filling process of the sliding surface shaping | molding method of the cylinder block which concerns on 1st Embodiment of this invention, sectional drawing which shows the structure of a cylinder block, and the compacting body formed in the bottom part side of a cylinder bore FIG. It is a figure explaining the compression filling process of the sliding surface shaping | molding method of the cylinder block which concerns on 1st Embodiment of this invention, sectional drawing which shows the structure of a cylinder block, and the compact formed on the entrance / exit side of the piston of a cylinder bore It is a figure which expands and shows the structure of a molded object. It is sectional drawing which shows the structure of the sliding surface of the cylinder bore in the cylinder block to which the sliding surface shaping | molding method of the cylinder block which concerns on 1st Embodiment of this invention was applied. It is a figure explaining the compression filling process of the sliding face molding method of the cylinder block which concerns on 2nd Embodiment of this invention, sectional drawing which shows the structure of a cylinder block, and the compacting body formed in the bottom part side of a cylinder bore FIG. It is a figure explaining the compression filling process of the sliding face shaping | molding method of the cylinder block which concerns on 2nd Embodiment of this invention, sectional drawing which shows the structure of a cylinder block, and the compact formed on the entrance / exit side of the piston of a cylinder bore It is a figure which expands and shows the structure of a molded object. It is a figure explaining the compression filling process of the sliding surface shaping | molding method of the cylinder block which concerns on 3rd Embodiment of this invention, sectional drawing which shows the structure of a cylinder block, and direction with respect to the central axis of a cylinder block among cylinder bores. It is a figure which expands and shows the structure of the compacting body formed in the area | region of the center direction side. It is a figure explaining the compression filling process of the sliding surface shaping | molding method of the cylinder block which concerns on 3rd Embodiment of this invention, and is a sectional view of a cylinder block, and a centrifugal direction side is provided with respect to the central axis of a cylinder block among cylinder bores. It is a figure which expands and shows the structure of the compacting body formed in the area | region. It is sectional drawing which shows the structure of the sliding surface of the cylinder bore in the cylinder block to which the sliding surface shaping | molding method of the cylinder block which concerns on 3rd Embodiment of this invention was applied. It is a top view which shows the structure of the sliding surface of the cylinder bore in the cylinder block to which the sliding surface shaping | molding method of the cylinder block which concerns on 3rd Embodiment of this invention was applied. As another example of the sliding surface of the cylinder bore in the cylinder block to which the method for forming the sliding surface of the cylinder block according to the third embodiment of the present invention is applied, an area where the concentration of the highly slidable additive element is high is enlarged. It is a top view which shows the structure formed in this way. As another example of the sliding surface of the cylinder bore in the cylinder block to which the method for forming a sliding surface of the cylinder block according to the third embodiment of the present invention is applied, a region where the concentration of the highly slidable additive element is high is reduced. It is a top view which shows the structure formed in this way. As another example of the sliding surface of the cylinder bore in the cylinder block to which the method for forming a sliding surface of the cylinder block according to the third embodiment of the present invention is applied, a region where the concentration of the highly slidable additive element is high is reduced. It is a top view which shows the structure formed in the arbitrary positions around the axis | shaft of a cylinder bore.

  Hereinafter, a method for forming a sliding surface of a cylinder block according to the present invention and a form for carrying out the cylinder block will be described with reference to the drawings.

[First Embodiment of Cylinder Block Sliding Surface Forming Method]
A cylinder block sliding surface molding method according to a first embodiment of the present invention includes, for example, a variable displacement swash plate type axial piston pump (hereinafter referred to as a hydraulic pump for convenience) as the hydraulic rotating machine shown in FIG. 1 applies.

  As shown in FIG. 1, the hydraulic pump 1 includes a casing 2 that forms an outer shell, a rotating shaft 3 that is provided around the center of the casing 2 so as to be rotatable around the shaft, and the rotation of the rotating shaft 3. And a plurality of pistons 6 respectively accommodated in the cylinder bores 5 of the cylinder block 4. The cylinder block 4 rotates around the central axis A (see FIG. 2).

  The casing 2 includes a cylindrical casing body 11 that covers each member such as the rotating shaft 3 and the cylinder block 4, and a front casing 12 and a rear casing 13 that close both ends of the casing body 11. The rear casing 13 has a pair of supply / discharge passages 14 </ b> A and 14 </ b> B through which hydraulic oil is supplied to or discharged from the cylinder block 4. These supply / discharge passages 14A and 14B are connected to piping and the like (not shown) provided on the suction side and discharge side of the hydraulic oil.

  The rotary shaft 3 is rotatably supported between the front casing 12 and the rear casing 13 via bearings 15 and 16. Further, the rotating shaft 3 is formed with a protruding end 3A protruding in the axial direction from the front casing 12, and the protruding end 3A side is rotationally driven by a motor (not shown) such as a diesel engine. The cylinder block 4 is splined to the outer peripheral side of the rotary shaft 3 and rotates together with the rotary shaft 3. The cylinder block 4 is arranged such that one end on the front casing 12 side of both end surfaces faces a swash plate 22 described later, and the other end on the rear casing 13 side of both end surfaces slides on a valve plate 25 described later. It is like that.

  The cylinder block 4 has the above-described plurality of cylinder bores 5 including the pistons 6 therein. These cylinder bores 5 are fixed around the central axis A of the cylinder block 4 around the rotation shaft 3. The cylinder block 4 is spaced apart and arranged in parallel to the axial direction of the central axis A of the cylinder block 4, that is, the axial direction of the rotary shaft 3. A cylinder port 5A is formed at one end of each cylinder bore 5 so as to intermittently communicate with or shut off the supply / discharge passages 14A and 14B of the rear casing 13 via a valve plate 25 described later.

  The hydraulic pump 1 is swingably held at the end of each piston 6 and provided with a plurality of shoes 21 rotating together with the cylinder block 4 and the front casing 12 of the casing 2 so as to be tiltable. A swash plate 22 slidably contacting each shoe 21, a plurality of shoe pressers 23 that respectively press each shoe 21 against the swash plate 22 side by the pressing force of each piston 6, and the front casing 12 are provided to swing the swash plate 22. A tilting actuator that tilts and drives a cradle 24 that is supported, a valve plate 25 that is disposed on the rear casing 13 side of the casing 2 and is provided between the rear casing 13 and the cylinder block 4. 26, 27.

  The swash plate 22 is provided so as to be tiltably supported by the cradle 24, and is provided by being fixed to the surface side of the swash plate main body 31, the smooth plate 32 on which the shoe 21 slides, and the rotating shaft 3. It consists of a shaft insertion hole 31A through which is inserted. The size of the shaft insertion hole 31 </ b> A is set so that the rotation shaft 3 does not hinder the tilting operation of the swash plate 22 when the rotation shaft 3 is inserted. The smooth plate 32 has a shaft insertion hole 32A through which the central portion is cut out and the rotation shaft 3 is inserted, like the shaft insertion hole 31A, and is formed in a donut-shaped disk shape.

  The cradle 24 is disposed on the back side of the swash plate 22 and is fixed to the front casing 12 of the casing 2. In addition, the cradle 24 is provided with a pair of tilting sliding surfaces 24A that are separated from each other on the left and right or up and down with the rotating shaft 3 interposed therebetween. The tilting sliding surfaces 24A can tilt the swash plate 22. It is formed in the concave curved circular arc surface so that it may support. The swash plate main body 31 is attached to the front casing 12 side so as to be tiltable via a tilting sliding surface 24A of the cradle 24. Further, the tilt actuators 26 and 27 variably control the tilt angle of the swash plate 22 in accordance with the tilt control pressure applied by supplying and discharging the tilt control pressure from the outside.

  Each shoe 21 is held in a state of being pressed against the surface 32B of the smooth plate 32 of the swash plate 22 via the shoe presser 23 and the like by the pressing force from each piston 6. The valve plate 25 is in sliding contact with the end face on the rear casing 13 side of both end faces of the cylinder block 4, and supports the cylinder block 4 so as to be rotatable together with the rotary shaft 3. The valve plate 25 is formed with a pair of supply / discharge ports 25A having an eyebrow shape. These supply / discharge ports 25A communicate with the supply / discharge passages 14A, 14B of the rear casing 13, and the cylinder block 4 When rotating around the axis of the rotary shaft 3, it communicates intermittently with the cylinder port 5 </ b> A of each cylinder bore 5.

  Here, when the rotary shaft 3 is driven to rotate by a prime mover such as an engine, the cylinder block 4 rotates integrally with the rotary shaft 3 around the rotary shaft 3. At this time, since the swash plate 22 is inclined with respect to the rotating shaft 3, as shown in FIG. 2, the piston 6 slides in the cylinder bore 5 from the top dead center to the bottom dead center, The discharge process of sliding in the cylinder bore 5 from the bottom dead center to the top dead center is repeated.

  Accordingly, in the piston 6 intake process, for example, hydraulic oil is drawn into the cylinder bore 5 from the supply / discharge passage 14B, and in the piston 6 discharge process, the hydraulic oil is discharged from the cylinder bore 5 to the supply / discharge passage 14A as high-pressure pressure oil. Is done. At that time, in the cylinder bore 5, the piston 6 strokes from the top dead center to the bottom dead center and sucks the hydraulic oil, and the stroke from the bottom dead center to the top dead center is pushed away. The positive pressure due to this acts repeatedly. Since the stroke length of the piston 6 is increased or decreased by the inclination of the swash plate 22 with respect to the rotation shaft 3, the tilt actuators 26 and 27 control the tilt angle of the swash plate 22, so that the hydraulic oil in the cylinder bore 5 is controlled. The suction amount and the discharge amount are adjusted.

  Further, when the cylinder block 4 rotates, the piston 6 rotates around the central axis A of the cylinder block 4, so that while the piston 6 reciprocates in the cylinder bore 5, the piston 6 moves from the rotating shaft 3 to the centrifugal direction side ( A centrifugal force toward the radial direction) acts. As a result, as shown in FIG. 3, the piston 6 receives an eccentric load in the cylinder bore 5 and tilts with respect to the central axis A of the cylinder block 1. Move. For this reason, a very high sliding surface pressure acts on the contact portion, and therefore, the sliding surface of the cylinder bore 5 is likely to be worn or seized.

  Therefore, in the first embodiment of the present invention, surface treatment is performed on the cylindrical surface inside the cylinder bore 5 of the cylinder block 4, and coating layers 46A and 46B (see FIG. 6) are formed on the cylindrical surface inside the cylinder bore 5. By molding the sliding surface of the cylinder bore 5, the cylinder bore 5 is protected from wear and seizure accompanying sliding with the piston 6.

  Hereinafter, the sliding surface molding method of the cylinder block 4 according to the first embodiment of the present invention and the cylinder block 4 to which the method is applied will be described in detail with reference to FIGS.

  As shown in FIG. 4 to FIG. 6, the method for forming a sliding surface of the cylinder block 4 according to the first embodiment of the present invention uses a powder 44 containing a copper alloy 41 and a highly slidable additive element 42 as a cylinder. A compression filling step for compressing and filling the cylinder bore 5 of the block 4 to form a compacting body in close contact with the cylindrical surface inside the cylinder bore 5, and a compacting body formed by the compression filling step are sintered. A sintering process and a finishing process for finishing the sliding surface of the cylinder bore 5 to a shape finally used are provided after the sintering process.

  And in the sliding face shaping | molding method of the cylinder block 4 which concerns on 1st Embodiment of this invention, the density | concentration of the highly slidable additive element 42 contained in a compacting body is the cylinder bore 5 in the above-mentioned compression filling process. The high-sliding additive element 42 is dispersed in the green compact so as to be different in the axial direction.

  Specifically, as shown in FIG. 4, the outer shape of the cylinder block 4 is manufactured by first cutting a steel material that is a material of the cylinder block 4. Next, in the compression filling process, after preparing a powder 44 composed of an assembly of copper alloy particles 43 which is composed of a component that is a base of the copper alloy 41 and contains the additive element 42 having high slidability therein, the copper alloy is prepared. Filling the cylinder bore 5 with the powder 44 is performed twice while changing the weight ratio of the copper alloy 41 and the highly slidable additive element 42 in the particles 43.

  In the first embodiment of the present invention, in order to change the weight ratio of the copper alloy 41 and the highly slidable additive element 42 in the copper alloy particles 43 in the first filling and the second filling, first, the high sliding The powder 44A made of an aggregate of copper alloy particles 43A containing the additive additive element 42 at a ratio of Bwt% inside is filled in the cylinder bore 5, and the powder 44A is compressed and solidified to form a compacted body. A compression-solidified layer 45A is formed.

  After that, as shown in FIG. 5, powder 44 </ b> B composed of an aggregate of copper alloy particles 43 </ b> B containing high-sliding additive element 42 at a ratio of Cwt% is filled on compression-solidified layer 45 </ b> A of cylinder bore 5. Then, by compressing and solidifying the powder 44B, a compression-solidified layer 45B is formed as a powder compact.

  At this time, of the compression-solidified layers 45A and 45B, the concentration of the highly slidable additive element 42 in the compression-solidified layer 45B formed on the inlet / outlet side of the piston 6 is the compression-solidified layer formed on the bottom side of the cylinder bore 5. The concentration is set higher than the concentration of the additive element 42 having a high slidability of 45A. That is, the high slidability additive element 42 in the copper alloy particles 43B is contained more than the high slidability additive element 42 in the copper alloy particles 43A (Bwt% <Cwt%). The highly slidable additive element 42 in each of the copper alloy particles 43A and 43B is composed of at least one of lead and bismuth, for example, both lead and bismuth, which is larger than the specific gravity of copper. Is set below a predetermined regulation value.

  In this manner, by adding the high slidable additive element 42 in the copper alloy particles 43 in a predetermined ratio according to the order of filling the powder 44A, 44B into the cylinder bore 5, The highly slidable additive element 42 can be uniformly dispersed throughout each of the compression-solidified layers 45A and 45B. Further, by adjusting the height of each compression-solidified layer 45A, 45B in the cylinder bore 5, the high slidability additive element 42 is added to the portion of the cylindrical surface inside the cylinder bore 5 where the sliding surface pressure is increased. High density and selective placement. As a result, the degree of freedom in forming the sliding surface of the cylinder bore 5 can be increased.

  In the sintering process, each of the compression-solidified layers 45A and 45B formed in the compression-filling process is sintered under a predetermined condition, so that high slidability is achieved in the axial direction of the cylinder bore 5, as shown in FIG. The coating layers 46A and 46B of the copper alloy 41 having different concentrations of the additive element 42 are formed and joined to the cylindrical surface inside the cylinder bore 5. In the finishing step, the central portions of the coating layers 46A and 46B and the bottom of the cylinder block 4 are cut or ground to remove the coating layers 46A and 46B, and finish the coating layers 46A and 46B to a predetermined size and surface roughness. Port 5A is formed. Thereby, the cylinder block 4 by which the desired sliding surface was shape | molded by the cylindrical surface inside the cylinder bore 5 can be obtained.

  That is, the sliding surface of the cylinder bore 5 is configured to contain the copper alloy 41 and the highly slidable additive element 42, and the concentration of the highly slidable additive element 42 in the axial direction of the cylinder bore 5 is different. 46B, of these coating layers 46A and 46B, the coating layer 46B has a high slidability additive element 42 on the bottom side of the cylinder bore 5 such that the concentration of the high slidability additive element 42 on the inlet / outlet side of the piston 6 It functions as a high density part higher than the density of 42.

  According to the sliding surface molding method of the cylinder block 4 according to the first embodiment of the present invention configured as described above, the compression solidified layers 45A and 45B having different concentrations of the highly slidable additive element 42 in the cylinder bore 5 are different. Is laminated along the axial direction of the cylinder bore 5, and the compression-solidified layers 45A and 45B are sintered in a state where the high-sliding additive element 42 is dispersed throughout the compression-solidified layers 45A and 45B. Lead and bismuth exhibiting a sliding performance higher than that of copper can be concentrated and distributed in a region where the sliding surface pressure is increased by sliding while the piston 6 contacts the cylindrical surface inside the cylinder bore 5. Therefore, even if lead and bismuth are not spread evenly over the entire cylindrical surface inside the cylinder bore 5, the wear and seizure phenomenon in the cylinder bore 5 can be sufficiently suppressed. Thereby, since the usage-amount of lead and bismuth may be small, manufacturing cost can be reduced.

  Furthermore, in the method for forming the sliding surface of the cylinder block 4 according to the first embodiment of the present invention, as one of the surface treatments of the cylinder bore 5, the compression solidified layers 45A and 45B formed in the cylinder bore 5 are sintered. Since it is used, it is possible to obtain the coating layers 46A and 46B that protect the cylinder bore 5 from sliding accompanied by the contact of the piston 6 without managing strict cooling temperature conditions in each step. In this manner, the sliding surface of the cylinder bore 5 can be easily and inexpensively molded, and excellent sliding performance can be exhibited.

  In the method for forming the sliding surface of the cylinder block 4 according to the first embodiment of the present invention, the concentration of the highly slidable additive element 42 in the upper compression-solidified layer 45B in the cylinder bore 5 is the same as that of the lower compression-solidified layer. Since it is higher than the concentration of the highly slidable additive element 42 in 45A, as shown in FIG. 3, the sliding surface pressure is increased by sliding the piston 6 while coming into contact with the cylindrical surface inside the cylinder bore 5. Lead and bismuth of the additive element 42 having high slidability can be concentrated in the portion D that becomes higher. Therefore, since the piston 6 hits the coating layer 46B containing a large amount of lead and bismuth to protect the cylinder bore 5, the probability of occurrence of wear and seizure in the cylinder bore 5 can be reduced, and the life of the cylinder block 4 can be increased. Can be planned.

  In the sliding surface molding method for the cylinder block 4 according to the first embodiment of the present invention, the powders 44A and 44B filled in the cylinder bore 5 are replaced with the highly slidable additive element 42 in the compression filling step. By comprising each of the aggregates of the copper alloy particles 43A and 43B contained therein, the highly slidable additive element 42 is dispersed throughout without being biased to a part of the compression-solidified layers 45A and 45B. It is possible to obtain a sliding surface of the cylinder bore 5 in which is secured.

  In particular, the aggregate of the copper alloy particles 43 </ b> A and 43 </ b> B has a structure in which the highly slidable additive element 42 is bonded to any of the components that form the base of the copper alloy 41 and is deposited on the base of the copper alloy 41. Therefore, the copper alloy particles 43A and 43B are easily bonded to each other by sintering the compression-solidified layers 45A and 45B in the sintering process, and the mechanical strength when the compression-solidified layers 45A and 45B are formed as the covering materials 46A and 46B is sufficient. Can be maintained.

  Further, in the method for forming the sliding surface of the cylinder block 4 according to the first embodiment of the present invention, inexpensive lead is used as a predetermined specified amount as the highly slidable additive element 42 which is a component of the compression-solidified layers 45A and 45B. Using only the following amounts, and using bismuth together, each compression-solidified layer 45A, 45B is well balanced with a good balance between the environmental impact of lead and the increased manufacturing cost due to the use of bismuth. The total amount of the high slidability additive element contained can be sufficiently secured. Thereby, the cylinder block 4 which exhibits higher sliding performance on the sliding surface of the cylinder bore 5 can be manufactured.

[Second Embodiment of Cylinder Block Sliding Surface Forming Method]
The second embodiment of the present invention differs from the first embodiment described above in that, as shown in FIGS. 4 and 5, in the compression filling process according to the first embodiment, the powder 44 filled in the cylinder bore 5 is used. However, in the compression filling process according to the second embodiment, as shown in FIGS. 7 and 8, the cylinder bore is made of an aggregate of copper alloy particles 43 containing the highly slidable additive element 42 therein. 5 is a plurality of high-sliding elements composed of only a plurality of copper alloy particles 43C that do not contain the high-sliding additive element 42 and the high-sliding additive element 42. It consists of a mixed powder in which the active particles 48 are mixed. In the configuration of the second embodiment of the present invention, the same or corresponding parts as those in the first embodiment are denoted by the same reference numerals.

  In the method for forming a sliding surface of the cylinder block 4 according to the second embodiment of the present invention, after the outer shape of the cylinder block 4 is produced, the copper alloy particles 43C in the mixed powder 47 and the high-sliding are compressed in the compression filling process. The mixed powder 47 is filled into the cylinder bore 5 twice while changing the mixing ratio with the conductive particles 48 in the middle.

  Specifically, in the second embodiment of the present invention, in order to change the mixing ratio of the copper alloy particles 43C and the highly slidable particles 48 in the mixed powder 47 in the first filling and the second filling, As shown in FIG. 7, after mixing the copper alloy particles 43C and the highly slidable particles 48 distributed so that the weight ratio of the highly slidable particles 48 becomes Bwt%, this mixed powder 47A is placed in the cylinder bore 5. And the mixed powder body 47A is compressed and solidified to form a compression-solidified layer 45C as a compacted body.

  Thereafter, as shown in FIG. 8, after the copper alloy particles 43C distributed so that the weight ratio of the highly slidable particles 48 is Cwt% and the highly slidable particles 48 are mixed, this mixed powder 47B is mixed. The cylinder bore 5 is filled on the compression-solidified layer 45C, and the mixed powder body 47B is compressed and solidified to form a compression-solidified layer 45D as a compacted body. The other configurations of the second embodiment are the same as the configurations of the first embodiment, and thus redundant description is omitted.

  According to the sliding surface molding method of the cylinder block 4 according to the second embodiment of the present invention configured as described above, the same effect as the first embodiment described above can be obtained, and a highly slidable additive element can be obtained. Even if 42 is not included in the copper alloy particles 43C in advance, the concentration of the highly slidable additive element 42 in the compression solidified layers 45C and 45D formed in the compression filling process can be adjusted as intended. The sliding surface can be efficiently formed. Thereby, productivity in manufacture of the cylinder block 4 can be increased.

[Third Embodiment of Cylinder Block Sliding Surface Forming Method]
The third embodiment of the present invention differs from the second embodiment described above in that, as shown in FIGS. 7 and 8, in the compression filling process according to the second embodiment, the compression-solidified layers 45C and 45D, that is, the pressure The high slidability additive element 42 is dispersed in the green compact so that the concentration of the high slidability additive element 42 contained in the powder compact is different in the axial direction of the cylinder bore 5. 9, in the compression filling process according to the third embodiment, as shown in FIG. 10, the concentration of the highly slidable additive element 42 contained in the green compact is different so that the concentration around the axis of the cylinder bore 5 is different. This is because the additive element 42 having high slidability is dispersed in the molded body. In addition, the same code | symbol is attached | subjected to the part which is the same as that of 2nd Embodiment among the structure of 3rd Embodiment of this invention, or respond | corresponds.

  In the method for forming a sliding surface of the cylinder block 4 according to the third embodiment of the present invention, the mixed powder 47 is formed in the compression filling process after the outer shape of the cylinder block 4 is produced, as in the second embodiment described above. The mixed powder 47 is filled into the cylinder bore 5 twice while changing the mixing ratio of the copper alloy particles 43C and the highly slidable particles 48 in the middle.

  Specifically, in the third embodiment of the present invention, in order to change the mixing ratio of the copper alloy particles 43C and the highly slidable particles 48 in the mixed powder 47 in the first filling and the second filling, As shown in FIG. 9, the interior of the cylinder bore 5 is divided into a region on the centripetal side (radially inner side) and a region on the centrifugal direction side (radially outer side) with respect to the central axis A of the cylinder block 4. Thus, the partition plate 51 that divides the cylinder bore 5 in half is inserted.

  Next, after mixing the copper alloy particles 43C distributed so that the weight ratio of the highly slidable particles 48 becomes Bwt% and the highly slidable particles 48, the mixed powder 47A is placed in the cylinder bore 5 with the above centroid. By filling the region on the direction side and compressing and solidifying the mixed powder 47A, the compression-solidified layer 45E is formed as a compacted body.

  Thereafter, as shown in FIG. 10, the partition plate 51 is removed from the cylinder bore 5, and the copper alloy particles 43C and the highly slidable particles 48 distributed so that the weight ratio of the highly slidable particles 48 is Cwt% are mixed. After that, the mixed powder 47B is filled in the region on the centrifugal direction side of the cylinder bore 5, and the mixed powder body 47B is compressed and solidified, thereby forming a compression-solidified layer 45F as a compacted body. Since the configuration of the other third embodiment is the same as the configuration of the second embodiment, a duplicate description is omitted.

  According to the sliding surface molding method of the cylinder block 4 according to the third embodiment of the present invention configured as described above, the same function and effect as those of the second embodiment described above can be obtained, as shown in FIGS. As described above, in the cylindrical surface inside the cylinder bore 5, the coating layer 46C in which the concentration of the highly slidable additive element 42 is different between the portion on the centripetal side and the portion on the centrifugal direction side with respect to the central axis A of the cylinder block 4. , 46D can be obtained.

  That is, the sliding surface of the cylinder bore 5 is composed of coating layers 46C and 46D in which the concentration of the highly slidable additive element 42 is different around the axis of the cylinder bore 5, and of these coating layers 46C and 46D, The concentration of the highly slidable additive element 42 on the centrifugal direction side with respect to the central axis A of the cylinder block 4 is such that the concentration of the highly slidable additive element 42 on the centripetal side with respect to the central axis A of the cylinder block 4 is high. It functions as a high density part higher than the density.

  Therefore, with the centrifugal force acting on the piston 6 when the cylinder block 4 is rotated, the entire portion on the centrifugal direction side where the sliding surface pressure tends to be high among the cylindrical surfaces inside the cylinder bore 5 is highly slidable. The coating layer 46D having a high density of the additional element 42 can be accurately protected. Thereby, durability of the cylinder block 4 can be improved.

  The above-described embodiments of the present invention have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment.

  That is, in the compression filling step according to each embodiment of the present invention, the concentration of the highly slidable additive element 42 included in the green compact is different in either the axial direction of the cylinder bore 5 or around the axis. The case where the highly slidable additive element 42 is dispersed in the green compact has been described. However, the concentration of the high slidable additive element 42 contained in the green compact is such that the concentration of the high slidable additive 42 in the axial direction of the cylinder bore 5 and around the axis. It is also possible to disperse the highly slidable additive element 42 in the green compact so that the two are different.

  Moreover, each embodiment of this invention is a compression filling process. WHEREIN: While changing the weight ratio of the copper alloy 41 in the copper alloy particle 43 and the high slidability additive element 42 on the way, the powder 44 to the cylinder bore 5 is provided. Although the case where the filling is performed twice has been described, the present invention is not limited to this case, and the weight ratio of the copper alloy 41 in the copper alloy particles 43 to the additive element 42 having high slidability is described. It is also possible to fill the cylinder bore 5 with the powder 44 three times or more while changing the value in the middle.

  Furthermore, although each embodiment of this invention demonstrated the case where both lead and bismuth were used as the highly slidable additive element 42, this invention is not limited to this case, Lead and bismuth of Either one may be used, and other elements may be used as long as they exhibit high sliding performance. In particular, the second embodiment of the present invention is used as the highly slidable additive element 42 even if it is an element that is difficult to contain in the copper alloy particles 43C, that is, an element that is difficult to combine with the component that forms the base of the copper alloy 41. Therefore, the degree of freedom in selecting the highly slidable additive element 42 can be increased.

  In the first embodiment of the present invention, after the compression-solidified layers 45A and 45B are laminated inside the cylinder bore 5 in the compression filling process, the compression-solidified layers 45A and 45B are sintered in the sintering process to cover the coating layers 46A, The case where 46B is formed and the central portions of the coating layers 46A and 46B are cut or ground in the finishing process has been described. However, the present invention is not limited to this case, and the coating layer is formed in the compression filling process. A core or the like (not shown) for forming the molds 46A and 46B may be used.

  The core is formed of, for example, a cylindrical body whose size is set smaller than the piston 6 inserted into the cylinder bore 5, and is inserted into the cylinder bore 5 in a state of being separated from the cylindrical surface inside the cylinder bore 5. Yes. In this case, in the finishing process, the amount by which the coating layers 46A and 46B are processed and removed simply by removing the core from the cylinder bore 5 is greatly reduced, so that the finishing operation can be rapidly advanced.

  Further, the second embodiment of the present invention is composed of only a plurality of copper alloy particles 43C that do not contain the highly slidable additive element 42 and the highly slidable additive element 42 in the compression filling step. Although the case where the mixed powder 47 mixed with a plurality of highly slidable particles 48 is filled in the cylinder bore 5 has been described, the present invention is not limited to this case. The cylinder bore 5 may be filled with a mixed powder obtained by mixing a plurality of copper alloy particles 43C that do not contain 42 and a plurality of alloys that contain the highly slidable additive element 42 therein.

  Furthermore, as shown in FIG. 12, the third embodiment of the present invention has a coating layer 46C having a low concentration of the highly slidable additive element 42 on the cylindrical surface inside the cylinder bore 5, and a highly slidable layer. Although the case where the coating layer 46D having a high concentration of the additive element 42 is formed at the same volume ratio has been described, the present invention is not limited to this case.

  As a specific example, as shown in FIG. 13, by setting the volume ratio of the coating layer 46D in which the concentration of the high slidability additive element 42 is high, a high slidability of the sliding surface of the cylinder bore 5 is set. The region where the concentration of the additive element 42 is high may be enlarged, or the volume ratio of the coating layer 46C where the concentration of the highly slidable additive element 42 is low is set large as shown in FIG. Accordingly, a region where the concentration of the highly slidable additive element 42 is high in the sliding surface of the cylinder bore 5 may be reduced. In addition, as shown in FIG. 15, the region where the concentration of the highly slidable additive element 42 is high in the sliding surface of the cylinder bore 5 may be reduced and formed at any position around the axis of the cylinder bore 5.

DESCRIPTION OF SYMBOLS 1 ... Hydraulic pump (hydraulic rotary machine), 3 ... Rotating shaft, 4 ... Cylinder block, 5 ... Cylinder bore, 5A ... Cylinder port, 6 ... Piston, 22 ... Swash plate, 25 ... Valve plate 41 ... Copper alloy, 42 ... Additive elements with high slidability, 43, 43A, 43B, 43C ... copper alloy particles, 44, 44A, 44B ... powder, 45A, 45B, 45C, 45D, 45E, 45F ... compression solidified layer (compacted compact), 46A, 46C ... coating layer, 46B, 46D ... coating layer (high concentration part), 47, 47A, 47B ... mixed powder, 48 ... highly slidable particles, 51 ... partition plate

Claims (6)

With respect to the cylindrical surface inside the cylinder bore of the hydraulic rotary machine, which includes a rotary shaft, a cylinder block that rotates around the central axis as the rotary shaft rotates, and a piston that is accommodated in the cylinder bore of the cylinder block. The cylinder block sliding surface molding method for performing surface treatment and molding the sliding surface of the cylinder bore,
A compression filling step of compressing and filling a powder containing a copper alloy and an additive element having high slidability into the cylinder bore, and forming a compact formed in close contact with the cylindrical surface inside the cylinder bore;
A sintering step of sintering the green compact formed in the compression filling step,
In the compression filling step, the high-sliding shape in the green compact is such that the concentration of the highly slidable additive element contained in the green compact is different from at least one of the axial direction and the axis of the cylinder bore. A method for forming a sliding surface of a cylinder block, wherein a dynamic additive element is dispersed. In the sliding method of the cylinder block according to claim 1,
The powder is composed of a component that becomes a base of the copper alloy, and is composed of an aggregate of copper alloy particles containing the highly slidable additive element therein,
The filling of the powder into the cylinder bore in the compression filling step is performed while changing the weight ratio of the copper alloy and the highly slidable additive element in the copper alloy particles. Cylinder block sliding surface molding method. In the sliding method of the cylinder block according to claim 1,
The powder is composed of a component serving as a base of the copper alloy, and a plurality of copper alloy particles not containing the highly slidable additive element therein, and a plurality of composed only of the highly slidable additive element. Consisting of a mixed powder mixed with highly slidable particles of
The cylinder block is characterized in that the filling of the powder into the cylinder bore in the compression filling step is performed while changing the mixing ratio of the copper alloy particles and the highly slidable particles in the mixed powder. Sliding surface forming method. Provided in a hydraulic rotating machine having a rotation shaft, a cylinder bore arranged around the rotation shaft, and a piston accommodated in the cylinder bore, and slides on the piston formed on a cylindrical surface inside the cylinder bore. A cylinder block including a moving surface,
The sliding surface is configured to contain a copper alloy and a highly slidable additive element, and the coating layer has a different concentration of the highly slidable additive element in at least one of the axial direction and around the axis of the cylinder bore. Cylinder block characterized by comprising. In the cylinder block according to claim 4,
The coating layer has a high concentration portion in which the concentration of the highly slidable additive element on the inlet / outlet side of the piston is higher than the concentration of the highly slidable additive element on the bottom side of the cylinder bore. Cylinder block. In the cylinder block according to claim 4,
In the coating layer, the concentration of the highly slidable additive element on the centrifugal direction side with respect to the rotation axis is higher than the concentration of the highly slidable additive element on the centripetal side with respect to the rotation axis. A cylinder block having a high concentration portion.