JP6542655B2 - Sliding surface molding method for cylinder block - Google Patents

Description

The present invention relates to a sliding surface molding how the cylinder block forming the sliding surface of the cylinder block in the hydraulic rotary machine such as a hydraulic pump or a hydraulic motor.

  In general, hydraulic drive devices such as hydraulic rotary machines represented by hydraulic pumps and hydraulic motors are composed of a number of sliding parts, and the sliding surface is out of lubricating oil film due to high sliding surface pressure, Also, due to the influence of instability of sliding contact state due to fluctuation of control oil pressure, etc., there is a risk of occurrence of seizing between sliding surfaces or abnormal wear locally, so the material of these sliding parts Mainly steel materials are used.

  Therefore, although 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, in particular, the cylinder bore is worn away by sliding with the piston which is a sliding partner. Since the seizure phenomenon is likely to occur, in order to suppress the occurrence of these abrasion and seizure phenomena, the surface of the sliding surface of the cylinder bore and piston is subjected to various surface modifications such as surface modification and surface treatment. .

  As one of the prior art of such surface treatment, a cylindrical formed body of a copper-based material, ie, a copper alloy liner is joined by sintering to the inside of the cylinder bore of a cylinder block made of iron-based material, and the density after this joining A sintered-bonded cylinder block in which the density of the sintered compact is made higher than that of a cylindrical compact before sintering has been proposed as one of the prior art (see, for example, Patent Document 1).

  Although this prior art sintered bonded cylinder block avoids the sticking of both sliding surfaces due to the seizure of the piston and the cylinder bore by the copper alloy liner sintered inside the cylinder bore, this copper alloy liner is made of lead bronze It is generally formed to have a lead content of 10% or more, which is not preferable in consideration of environmental impact and the like.

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

  Here, as one of the prior art useful for the development of a cylinder block in which the lead content of the copper alloy is suppressed, bismuth, nickel and sulfur are contained respectively in predetermined proportions in a bronze alloy containing copper and tin as main components In addition, by adding bismuth, nickel, and sulfur to copper and tin, it has a fine laminated structure in which flake-like copper-tin intermetallic compounds are precipitated in .alpha. There is known a method for producing a bronze alloy in which a dispersed precipitated eutectoid phase appears (see, for example, Patent Document 2).

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

JP 10-196552 A Unexamined-Japanese-Patent No. 2010-31347

  However, in the method of producing a bronze alloy according to the prior art disclosed in Patent Document 2, copper tin is controlled by controlling the eutectoid transformation progressing in two steps in a predetermined temperature range with additional elements of bismuth, nickel and sulfur. Since the fine laminated structure of the metallic intermetallic compound and the eutectoid phase of the metal fine particles such as bismuth are deposited, the fine laminated structure and the eutectoid phase are precipitated when casting and manufacturing a special bronze alloy. The problem is that the temperature conditions for cooling are very strict and manufacturing control is difficult. Therefore, the bronze alloy manufactured by the manufacturing method of the bronze alloy of the prior art is not suitable as a sliding member applied to the sliding surface of the cylinder bore of the cylinder block.

  Moreover, although the manufacturing method of the bronze alloy of a prior art is making bismuth the essential addition element in order to disperse-deposit the eutectoid phase of metal microparticles, such as bismuth, as mentioned above, since this bismuth is a rare metal The cost is high, and there is concern that the production cost will significantly increase when used as a substitute for lead. Therefore, even when bismuth is used in this way, although it is desirable that the addition amount of bismuth be as small as possible, bismuth is necessary for dispersing and precipitating as described above to lower the eutectoid transformation temperature. Not only that, since it is an element that improves the pressure resistance, there is a possibility that the sliding performance such as the wear friction characteristics and the seizure resistance in the sliding member may be lowered by reducing the addition amount of bismuth.

The present invention has been made from the circumstances of the prior art as described above, and an object thereof is to form a sliding surface of a cylinder bore easily and inexpensively, and to exhibit excellent sliding performance. and to provide a sliding surface molding how.

In order to achieve the above object, the method for forming a sliding surface of a cylinder block according to the present invention comprises a rotation axis, a cylinder block rotating around a central axis as the rotation axis rotates, and a cylinder bore of the cylinder block A method of forming a sliding surface of a cylinder block, comprising the steps of: performing surface treatment on a cylindrical surface inside the cylinder bore of a hydraulic rotating machine having a piston housed in the cylinder, and forming a sliding surface of the cylinder bore, A compacting step of compacting and filling a powder containing an alloy and a highly slidable additive element into the cylinder bore to form a compact formed in close contact with the cylindrical surface inside the cylinder bore; the compacting step a sintering step of sintering the formed the green compact in the green central portion of the molded body processed removed, the finishing step of forming a sliding surface on the cylindrical surface of the cylinder bore inner In the compacting step, the compacting step may be performed in the compacting body such that the concentration of the highly slidable additional element contained in the compacting body is different in at least one of an axial direction and an axis around the cylinder bore. It is characterized in that a highly slidable additive element is dispersed.

According to the sliding surface molding how the cylinder block of the present invention, the sliding surface of the cylinder can be molded easily and inexpensively, it is possible to exhibit excellent sliding performance. Problems, configurations, and effects other than those described above will be apparent from the description of the embodiments below.

It is a schematic sectional drawing of the variable displacement type swash plate type axial piston pump to which the sliding face molding method of the cylinder block which concerns on 1st Embodiment of this invention is applied. It is a figure explaining the operation | movement relationship of the cylinder block, piston, and valve plate which are shown in FIG. It is a figure explaining the sliding state of the cylinder bore and piston which are shown in FIG. It is a figure explaining the compression filling process of the sliding face formation method of a cylinder block concerning a 1st embodiment of the present invention, and is a sectional view showing the composition of a cylinder block, and the compacting body formed in the bottom side of a cylinder bore. FIG. 8 is a diagram showing the configuration of the circuit in an enlarged manner. It is a figure explaining the compression filling process of the sliding face formation method of the cylinder block concerning a 1st embodiment of the present invention, and is a sectional view showing the composition of a cylinder block, and the powder compact formed in the entrance and 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 face of the cylinder bore in the cylinder block to which the sliding face molding method of the cylinder block which concerns on 1st Embodiment of this invention is applied. It is a figure explaining the compression filling process of the sliding face formation method of the cylinder block concerning a 2nd embodiment of the present invention, and is a sectional view showing the composition of a cylinder block, and the compacting body formed in the bottom side of a cylinder bore. FIG. 8 is a diagram showing the configuration of the circuit in an enlarged manner. It is a figure explaining the compression filling process of the sliding face formation method of the cylinder block concerning a 2nd embodiment of the present invention, and is a sectional view showing the composition of a cylinder block, and the dust formed in the entrance and 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 face formation method of the cylinder block concerning a 3rd embodiment of the present invention, and is a sectional view showing the composition of a cylinder block, and it faces 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 cardiac direction side. It is a figure explaining the compression filling process of the sliding face formation method of the cylinder block concerning a 3rd embodiment of the present invention, and is a sectional view of a cylinder block, and the centrifugal direction side about 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 face of the cylinder bore in the cylinder block to which the sliding face molding method of the cylinder block which concerns on 3rd Embodiment of this invention is applied. It is a top view which shows the structure of the sliding face of the cylinder bore in the cylinder block to which the sliding face molding method of the cylinder block which concerns on 3rd Embodiment of this invention is applied. 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 a cylinder block according to the third embodiment of the present invention is applied, the region having a high concentration of additive elements with high sliding properties is expanded It is a top view which shows the structure formed. 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 a cylinder block according to the third embodiment of the present invention is applied, the region having a high concentration of additive elements with high sliding properties is reduced It is a top view which shows the structure formed. 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 a cylinder block according to the third embodiment of the present invention is applied, the region having a high concentration of additive elements with high sliding properties is reduced It is a top view which shows the structure formed in the arbitrary positions around the axis of a cylinder bore.

  Hereinafter, a method for forming a sliding surface of a cylinder block according to the present invention and an embodiment for carrying out the cylinder block will be described based on the drawings.

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

  As shown in FIG. 1, the hydraulic pump 1 includes a casing 2 forming an outer shell, a rotation shaft 3 rotatably provided about an axis at a central portion of the casing 2, and rotation of the rotation shaft 3. The cylinder block 4 rotates around the axis of the central axis A (see FIG. 2), and a plurality of pistons 6 accommodated in the respective cylinder bores 5 of the cylinder block 4.

  The casing 2 is composed of a cylindrical casing main body 11 which covers each member such as the rotary shaft 3 and the cylinder block 4, and a front casing 12 and a rear casing 13 which close both ends of the casing main body 11. The rear casing 13 has a pair of supply and discharge passages 14A and 14B for supplying or discharging the hydraulic oil into the cylinder block 4. These supply and discharge passages 14A and 14B are connected to pipes (not shown) provided on the suction side and the discharge side of the hydraulic oil.

  The rotating shaft 3 is rotatably supported between the front casing 12 and the rear casing 13 via bearings 15, 16 and the like. Further, the rotary shaft 3 is formed with a projecting end 3A that protrudes in the axial direction from the front casing 12. The projecting end 3A side is rotationally driven by a motor (not shown) such as a diesel engine, for example. The cylinder block 4 is splined to the outer peripheral side of the rotation shaft 3 and is integrally rotated with the rotation shaft 3. The cylinder block 4 is disposed such that one end on the front casing 12 side of the both ends faces the swash plate 22 described later, and the other end on the rear casing 13 side slidably contacts the valve plate 25 described later. It is supposed to be.

  The cylinder block 4 has the above-mentioned plurality of cylinder bores 5 including the respective pistons 6 therein, and each of the cylinder bores 5 is constant around the central axis A of the cylinder block 4 around the rotation axis 3. They are 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 rotation axis 3. At one end of each cylinder bore 5 is formed a cylinder port 5A which intermittently communicates with or shuts off the supply / discharge passage 14A, 14B of the rear casing 13 via a valve plate 25 described later.

  Further, the hydraulic pump 1 is swingably held at the end of each piston 6 and is provided so as to be able to tilt on the side of the front casing 12 among the plurality of shoes 21 rotating with the cylinder block 4 and the casing 2. The swash plate 22 provided on the front casing 12 is provided with a swash plate 22 in sliding contact with the shoes 21, a plurality of shoe presses 23 for pressing the shoes 21 against the swash plate 22 by the pressing force of the pistons 6, And a tilt actuator for driving the swash plate 22 so as to support the cradle 24 and the valve plate 25 disposed on the rear casing 13 side of the casing 2 and provided between the rear casing 13 and the cylinder block 4 26 and 27 are provided.

  The swash plate 22 is provided with a swash plate main body 31 supported so as to be able to rotate by the cradle 24, a smooth plate 32 fixedly provided on the surface side of the swash plate main body 31 and a shoe 21 sliding thereon. And a shaft insertion hole 31A through which the The size of the shaft insertion hole 31A is set so that the rotary shaft 3 does not interfere with the tilting operation of the swash plate 22 when the rotary shaft 3 is inserted. Further, the smooth plate 32 is hollowed at its central portion in the same manner as the shaft insertion hole 31A, has a shaft insertion hole 32A for inserting the rotation shaft 3, 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. Further, the cradle 24 is provided with a pair of tilting sliding surfaces 24A which are separated left and right or up and down on both sides of the rotating shaft 3, and the tilting sliding surface 24A can tilt the swash plate 22. It is formed in a concave curved arc surface to support. And the swash plate main body 31 is attached to the front casing 12 side so as to be able to tilt via the tilt sliding surface 24A of the cradle 24. Further, the tilting actuators 26 and 27 variably control the tilting angle of the swash plate 22 in accordance with the tilting control pressure to which the tilting control pressure is externally supplied and discharged.

  Each shoe 21 is held in a state where it is pressed against the surface 32 B of the smooth plate 32 of the swash plate 22 with a pressing force from each piston 6 via a shoe presser 23 or the like. The valve plate 25 is in sliding contact with the end surface on the rear casing 13 side of the both end surfaces of the cylinder block 4, and rotatably supports the cylinder block 4 together with the rotary shaft 3. Further, the valve plate 25 is formed with a pair of feeding and discharging ports 25A having a bowl shape, and these feeding and discharging ports 25A are in communication with the feeding and discharging passages 14A and 14B of the rear casing 13, and the cylinder block 4 is When rotating around the axis of the rotary shaft 3, the cylinder port 5 A of each cylinder bore 5 intermittently communicates with the cylinder port 5 A.

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

  Therefore, in the suction process of the piston 6, for example, the hydraulic oil is sucked into the cylinder bore 5 from the supply and discharge passage 14B, and in the discharge process of the piston 6, the hydraulic fluid is discharged from the cylinder bore 5 into the supply and discharge passage 14A as high pressure oil. Be done. At that time, the piston 6 strokes from the top dead center to the bottom dead center into the cylinder bore 5 and sucks the working oil, and strokes from the bottom dead center to the top dead center to push the working oil away. Positive pressure 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, 27 control the tilt angle of the swash plate 22. The suction amount and the discharge amount are adjusted.

  In addition, 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 within the cylinder bore 5, the piston 6 moves from the rotary shaft 3 in the centrifugal direction Radial force) acts on the centrifugal force. As a result, as shown in FIG. 3, the piston 6 receives a bias load in the cylinder bore 5 and inclines with respect to the central axis A of the cylinder block 1. Move. Therefore, a very high sliding surface pressure acts on this contact portion, so that the sliding surface of the cylinder bore 5 is susceptible to wear and seizing phenomena.

  Therefore, in the first embodiment of the present invention, the cylindrical surface on the inner side of the cylinder bore 5 of the cylinder block 4 is surface-treated, and the coating layers 46A and 46B (see FIG. 6) are formed on the cylindrical surface on the inner side of the cylinder bore 5 By forming the sliding surface of the cylinder bore 5, the cylinder bore 5 is protected from wear and seizing that accompany sliding with the piston 6.

  Hereinafter, a method of forming a sliding surface of a cylinder block 4 according to a first embodiment of the present invention and a cylinder block 4 to which the method is applied will be described in detail based on FIGS. 4 to 6.

  The sliding surface forming method of the cylinder block 4 according to the first embodiment of the present invention, as shown in FIG. 4 to FIG. 6, uses a powder 44 containing a copper alloy 41 and a high sliding additive element 42 as a cylinder. Compressing and filling the cylinder bore 5 of the block 4 to form a compact formed in close contact with the cylindrical surface inside the cylinder bore 5 and sintering the compact formed in the compacting step It comprises a sintering step and a finishing step of finishing the sliding surface of the cylinder bore 5 into a shape to be finally used after the sintering step.

  And, in the method for forming a sliding face of the cylinder block 4 according to the first embodiment of the present invention, in the above-mentioned compression filling step, the concentration of the additional element 42 having high slidability contained in the powder compact is the cylinder bore 5 The additive element 42 having high slidability 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 produced by first cutting the steel material which is the material of the cylinder block 4. Next, in the compression and filling step, a powder 44 is prepared which is composed of a component to be a base of the copper alloy 41 and contains an aggregate of copper alloy particles 43 containing the highly slidable additive element 42 therein. While changing the weight ratio of the copper alloy 41 in the particles 43 and the highly slidable additional element 42 in the middle, the powder 44 is filled into the cylinder bore 5 twice.

  In the first embodiment of the present invention, in order to change the weight ratio of the copper alloy 41 in the copper alloy particles 43 and the highly slidable additional element 42 in the first and second fillings, first, the high sliding A powder 44A consisting of an aggregate of copper alloy particles 43A internally containing an additive additive element 42 at a ratio of B wt% is filled in the cylinder bore 5, and the powder 44A is compressed and solidified to form a powder compact. The compressed and solidified layer 45A is formed.

  Thereafter, as shown in FIG. 5, a powder 44B consisting of an aggregate of copper alloy particles 43B containing a highly slidable additive element 42 at a C wt% ratio is filled on the compression solidified layer 45A of the cylinder bore 5 The powder 44B is compressed and solidified to form a compressed and solidified layer 45B as a green compact.

  At this time, of the compression solidified layers 45A and 45B, the concentration of the highly slidable additive element 42 of the compressed 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 bores 5 It is set higher than the concentration of the highly slidable additive element 42 of 45A. That is, the highly slidable additive element 42 in the copper alloy particles 43B is contained in a larger amount than the highly slidable additive element 42 in the copper alloy particles 43A (B wt% <C wt%). The highly slidable additive element 42 in each of the copper alloy particles 43A and 43B is made of at least one of lead and bismuth larger than the specific gravity of copper, for example, both lead and bismuth, and of these, the amount of lead added Is set to a predetermined regulation value or less.

  As described above, according to the order in which the powders 44A and 44B are filled into the cylinder bores 5, the highly slidable additional element 42 is contained in the copper alloy particles 43 in a predetermined ratio. The highly slidable additional element 42 can be uniformly dispersed in the entire compressed and solidified layers 45A and 45B. Further, by adjusting the heights of the respective compressively solidified layers 45A and 45B in the cylinder bore 5, the additional element 42 having high slidability is provided to the portion of the cylindrical surface inside the cylinder bore 5 where the sliding surface pressure becomes high. It can be arranged densely and selectively. This makes it possible to increase the degree of freedom in the formation of the sliding surface of the cylinder bore 5.

  In the sintering step, each compressed and solidified layer 45A, 45B formed in the compression filling step is sintered under a predetermined condition, as shown in FIG. The covering 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. Then, in the finishing step, the central portion of each of the coating layers 46A, 46B and the bottom of the cylinder block 4 are cut or ground and removed by machining to finish each of the coating layers 46A, 46B to a predetermined size and surface roughness. Form port 5A. As a result, it is possible to obtain the cylinder block 4 in which a desired sliding surface is formed on the cylindrical surface inside the cylinder bore 5.

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

  According to the sliding face molding method of the cylinder block 4 according to the first embodiment of the present invention thus configured, the compression solidified layers 45A, 45B in the cylinder bore 5 have different concentrations of the additional element 42 having high sliding properties. Are laminated along the axial direction of the cylinder bores 5 and the compression solidified layers 45A and 45B are sintered in a state in which the highly slidable additional element 42 is dispersed throughout the respective compression solidified layers 45A and 45B. By sliding while the piston 6 abuts against the cylindrical surface inside the cylinder bore 5, lead and bismuth, which exhibit higher sliding performance than copper, can be concentrated and distributed in a region where the sliding surface pressure becomes high. Therefore, even if lead and bismuth are not evenly distributed over the entire cylindrical surface inside the cylinder bore 5, the wear and seizing phenomenon in the cylinder bore 5 can be sufficiently suppressed. As a result, the use amount of lead and bismuth can be reduced, and the manufacturing cost can be reduced.

  Furthermore, in the sliding face molding method of the cylinder block 4 according to the first embodiment of the present invention, as one of the surface treatment of the cylinder bores 5, sintering of the respective compression solidified layers 45A, 45B formed in the cylinder bores 5 is performed. Because it is used, it is possible to obtain the coating layers 46A and 46B that protect the cylinder bores 5 from the sliding accompanied by the contact of the piston 6 without controlling the strict cooling temperature condition in each process. Thus, the sliding surface of the cylinder bore 5 can be formed easily and inexpensively, and excellent sliding performance can be exhibited.

  Further, in the method of forming the sliding surface of the cylinder block 4 according to the first embodiment of the present invention, the concentration of the additive element 42 having high slidability in the compression solidified layer 45B of the upper stage in the cylinder bore 5 is the compression solidified layer of the lower stage. Since the concentration of the additional element 42 having high slidability at 45 A is higher, as shown in FIG. Leads and bismuths of the highly slidable additive element 42 can be densely packed in the raised portion D. Therefore, since the cylinder bore 5 is protected by the piston 6 hitting the coating layer 46B containing a large amount of lead and bismuth, the occurrence probability such as wear and seizing phenomenon in the cylinder bore 5 can be reduced, and the life of the cylinder block 4 is increased. Can be

  Further, in the method for forming a sliding surface of the cylinder block 4 according to the first embodiment of the present invention, the powder 44A, 44B filled in the cylinder bore 5 in the compression filling step is made of the additional element 42 having high slidability. By respectively forming the aggregate of the copper alloy particles 43A and 43B contained inside, the highly slidable additional element 42 is dispersed in the whole without being biased to a part of the compressed and solidified layers 45A and 45B, so a good quality can be obtained. The sliding surface of the cylinder bore 5 can be obtained.

  In particular, the assembly of copper alloy particles 43A and 43B has a structure in which the highly slidable additive element 42 is combined with any of the components to be the base of the copper alloy 41 and is precipitated in the base of the copper alloy 41. Therefore, the copper alloy particles 43A and 43B are easily bonded to each other by the sintering of the compression solidified layers 45A and 45B in the sintering step, 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 of forming the sliding surface of the cylinder block 4 according to the first embodiment of the present invention, a predetermined prescribed amount of inexpensive lead is used as the highly slidable additional element 42 serving as a component of the compression solidified layers 45A, 45B. By using only the following amounts and additionally using bismuth, each compressed solidified layer 45A, 45B is well balanced between the environmental impact of lead and the manufacturing cost increased by the use of bismuth. The total amount of the highly slidable 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 Method of Forming Sliding Surface of Cylinder Block
The second embodiment of the present invention is different from the first embodiment in that the powder 44 filled in the cylinder bore 5 in the compression and filling process according to the first embodiment, as shown in FIGS. 4 and 5. Is composed of an aggregate of copper alloy particles 43 containing the highly slidable additive element 42 inside, as shown in FIG. 7 and FIG. 8, in the compression filling step according to the second embodiment, the cylinder bore The powder 47 filled in 5 contains a plurality of copper alloy particles 43C containing no highly slidable additive element 42 and a plurality of highly slidable slide elements composed of only highly slidable additive elements 42. It consists of the mixed powder which mixed with the sex particle 48. In the configuration of the second embodiment of the present invention, parts that are the same as or correspond to those in the first embodiment are given the same reference numerals.

  In the sliding face molding method of the cylinder block 4 according to the second embodiment of the present invention, after the outer shape of the cylinder block 4 is manufactured, the copper alloy particles 43C in the mixed powder 47 and the high sliding face in the compression filling step. The mixed powder 47 is charged twice into the cylinder bore 5 while changing the mixing ratio with the sex particles 48 on the way.

  Specifically, in the second embodiment of the present invention, in order to change the mixing ratio of the copper alloy particles 43C and the high sliding particles 48 in the mixed powder 47 in the first and second fillings, first, As shown in FIG. 7, after mixing the high sliding particles 48 with the copper alloy particles 43 C distributed so that the weight ratio of the high sliding particles 48 becomes B wt%, the mixed powder 47 A is contained in the cylinder bore 5 The mixed powder 47A is compressed and solidified to form a compressed and solidified layer 45C as a green compact.

  Thereafter, as shown in FIG. 8, after mixing the high sliding particles 48 with the copper alloy particles 43C distributed so that the weight ratio of the high sliding particles 48 becomes C wt%, this mixed powder 47B is The powder is filled on the compression solidified layer 45C of the cylinder bores 5, and the mixed powder 47B is compressed and solidified to form a compression solidified layer 45D as a powder compact. The configuration of the other second embodiment is the same as the configuration of the first embodiment, and thus the description thereof will not be repeated.

  According to the sliding face molding method for the cylinder block 4 according to the second embodiment of the present invention configured as described above, in addition to the same function and effect as the first embodiment described above, a highly slidable additional element Since the concentration of the highly slidable additional element 42 in the compression solidified layers 45C and 45D formed in the compression and filling step can be adjusted as intended even if 42 is not previously contained in the copper alloy particles 43C, the cylinder bore 5 Can be formed efficiently. Thereby, productivity in manufacture of cylinder block 4 can be improved.

Third Embodiment of Method of Forming Sliding Surface of Cylinder Block
As the third embodiment of the present invention differs from the second embodiment described above, as shown in FIG. 7 and FIG. 8, in the compression and filling process according to the second embodiment, the compression solidified layers 45 C and 45 D, ie, 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 differs in the axial direction of the cylinder bore 5, while As shown in FIG. 10 and FIG. 10, in the compacting and filling step according to the third embodiment, the powder compacting is performed so that the concentration of the highly slidable additional element 42 contained in the powder compacting body differs around the axis of the cylinder bore 5. It is that the highly slidable additional element 42 is dispersed in the molded body. In the configuration of the third embodiment of the present invention, parts that are the same as or correspond to those in the second embodiment are given the same reference numerals.

  In the method for forming a sliding surface of a cylinder block 4 according to the third embodiment of the present invention, as in the second embodiment described above, after the outer shape of the cylinder block 4 is produced, mixed powder 47 is obtained in the compression and filling step. The mixed powder 47 is filled twice into the cylinder bore 5 while changing the mixing ratio of the copper alloy particles 43C and the high slidability 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 high sliding particles 48 in the mixed powder 47 in the first and second fillings, first, As shown in FIG. 9, the inside of the cylinder bore 5 is divided into a region in the acentric direction (radially inner side) and a region in the centrifugal direction (radially outer side) with respect to the central axis A of the cylinder block 4 As such, the partition plate 51 which divides the cylinder bore 5 into halves is inserted.

  Next, after mixing the highly slidable particles 48 with the copper alloy particles 43C distributed so that the weight ratio of the highly slidable particles 48 is B wt%, the mixed powder 47A is made into the above-mentioned centering direction of the cylinder bores 5 By filling the region on the direction side and compressing and solidifying the mixed powder 47A, a compressed and solidified layer 45E is formed as a green compact.

  Thereafter, as shown in FIG. 10, the partition plate 51 is removed from the cylinder bore 5, and the high sliding particles 48 are mixed with the copper alloy particles 43C distributed so that the weight ratio of the high sliding particles 48 becomes C wt%. Thereafter, the mixed powder 47B is filled in the region of the cylinder bore 5 on the centrifugal direction side, and the mixed powder 47B is compressed and solidified to form a compressed and solidified layer 45F as a powder compact. The configuration of the other third embodiment is the same as the configuration of the second embodiment, and thus redundant description will be omitted.

  According to the sliding face molding method for the cylinder block 4 according to the third embodiment of the present invention configured as described above, the same effects as those of the above-described second embodiment can be obtained, and the method shown in FIGS. Thus, the coating layer 46C in which the concentration of the additional element 42 having high slidability is different in the part on the acentric direction side and the part on the centrifugal direction side with respect to the central axis A of the cylinder block 4 among the cylindrical surfaces inside the cylinder bore 5 , 46D can be obtained.

  That is, the sliding surface of the cylinder bore 5 is composed of the covering layers 46C and 46D having different concentrations of the additional element 42 having high slidability around the axis of the cylinder bore 5, and the covering layer 46D of these covering layers 46C and 46D is The concentration of the highly slidable additive element 42 in the centrifugal direction with respect to the central axis A of the cylinder block 4 is the concentration of the highly slidable additive element 42 in the centripetal direction with respect to the central axis A of the cylinder block 4 It functions as a high concentration part higher than the concentration.

  Therefore, due to the centrifugal force acting on the piston 6 when the cylinder block 4 rotates, the entire surface in the centrifugal direction where the sliding surface pressure tends to be high among the cylindrical surfaces inside the cylinder bore 5 has high slidability Can be precisely protected by the covering layer 46D having the high density of the additional element 42 of Thereby, the durability of the cylinder block 4 can be improved.

  The embodiments of the present invention described above are described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. Further, part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment.

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

  In each embodiment of the present invention, the powder 44 to the cylinder bore 5 is changed while changing the weight ratio between the copper alloy 41 in the copper alloy particles 43 and the highly slidable additional element 42 in the compression and filling step. Although the case where the filling was performed twice was described, the present invention is not limited to this case, and the weight ratio of copper alloy 41 in copper alloy particle 43 and additive element 42 of high sliding property is described. The filling of the powder 44 into the cylinder bore 5 may be performed three or more times while changing the value of.

  Furthermore, although each embodiment of the present invention has described the case where both lead and bismuth are used as the highly slidable additional element 42, the present invention is not limited to this case, and lead and bismuth can be used. Either one may be used, or another element may be used as long as it exhibits high sliding performance. In particular, the second embodiment of the present invention is used as the additive element 42 having high slidability, even if it is an element that is difficult to contain in the copper alloy particles 43 C, that is, an element that does not easily combine with the component that becomes the base of the copper alloy 41. Since this can be done, the degree of freedom in selecting the highly slidable additional element 42 can be enhanced.

  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 form the covering layer 46A, Although the case where 46B is formed and the central portion of the covering layers 46A and 46B is cut or ground in the finishing step and removed by machining is described, the present invention is not limited to this case, and the covering layer in the compression filling step is described. A core or the like (not shown) for forming a mold of 46A, 46B may be used.

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

  Moreover, in the second embodiment of the present invention, in the compression and filling step, only the copper alloy particles 43C not containing the highly slidable additive element 42 therein and the highly slidable additive element 42 are included. Although the case where the mixed powder 47 in which a plurality of highly slidable particles 48 are mixed is filled in the cylinder bore 5 is described, the present invention is not limited to this case, for example, an added element of high slidability The cylinder bore 5 may be filled with a mixed powder in which a plurality of copper alloy particles 43C not including 42 internally and a plurality of alloys internally including the highly slidable additional element 42 are mixed.

  Furthermore, as shown in FIG. 12, according to the third embodiment of the present invention, a coating layer 46C having a low concentration of the additive element 42 having high slidability with respect to the cylindrical surface inside the cylinder bore 5 and 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 having a high concentration of the highly slidable additional element 42 large, the highly slidable surface of the sliding surface of the cylinder bore 5 is obtained. The region where the concentration of the additive element 42 is high may be enlarged, or as shown in FIG. 14, the volume ratio of the covering layer 46C where the concentration of the additive element 42 having high slidability is low is set large. Thus, the region of the sliding surface of the cylinder bore 5 where the concentration of the highly slidable additional element 42 is high may be reduced. In addition, as shown in FIG. 15, a region of the sliding surface of the cylinder bore 5 where the concentration of the highly slidable additional element 42 is high may be reduced and formed at an arbitrary position around the axis of the cylinder bore 5.

DESCRIPTION OF SYMBOLS 1 ... hydraulic pump (hydraulic rotating machine), 3 ... rotating shaft, 4 ... cylinder block, 5 ... cylinder bore, 5 A ... 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: compacted layer (compacted compact) 46A, 46C: Coating layer, 46B, 46D: Coating layer (high concentration part), 47, 47A, 47B: Mixed powder, 48: High slidability particles, 51: Partition plate

Claims (3)

With respect to the cylindrical surface inside the cylinder bore of a hydraulic rotary machine provided with a rotary shaft, a cylinder block rotating around a central axis with rotation of the rotary shaft, and a piston accommodated in a cylinder bore of the cylinder block A method of forming a sliding surface of a cylinder block in which surface treatment is performed to form a sliding surface of the cylinder bore,
Compressing and filling a powder containing a copper alloy and a highly slidable additive element into the cylinder bore to form 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 ;
And finishing the process of removing the central portion of the green compact and forming a sliding surface on the cylindrical surface inside the cylinder bore ,
In the compacting step, the high-sliding portion is formed in the compact so that the concentration of the highly slidable additive element contained in the compact is different in at least one of the axial direction and the axis around the cylinder bore. A sliding surface forming method for a cylinder block, characterized in that a dynamic additive element is dispersed. In the sliding face forming method of a cylinder block according to claim 1,
The powder is composed of a component to be a base of the copper alloy, and is composed of an assembly of copper alloy particles containing the highly slidable additive element therein.
The filling of the powder into the cylinder bore in the compression and filling step is performed while changing the weight ratio of the copper alloy in the copper alloy particles and the highly slidable additive element on the way. Sliding surface molding method of cylinder block. In the sliding face forming method of a cylinder block according to claim 1,
The powder is composed of a component to be a base of the copper alloy, and a plurality of copper alloy particles that do not contain the highly slidable additive element therein, and a plurality of particles made of only the highly slidable additive element Consisting of mixed powder mixed with high sliding particles of
The cylinder block is characterized in that the filling of the powder into the cylinder bore in the compression and filling step is performed while changing the mixing ratio of the copper alloy particles in the mixed powder and the highly slidable particles on the way. Sliding surface molding method.