JP2013002282A - Method for manufacturing cylinder block of hydraulic rotating machine and hydraulic rotating machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a cylinder block of a hydraulic rotating machine that achieves a normal sliding state between a cylinder block and a sliding member and maintains a stable sliding state therebetween, and the hydraulic rotating machine.SOLUTION: The hydraulic rotating machine includes: a rotary shaft 9; a cylinder block 1 that rotates along with the rotation of the rotary shaft 9 and is formed of spherical graphite cast iron; and a piston 2 that is brought into sliding contact with the sliding surface of a cylinder 3 of the cylinder block 1. When manufacturing the cylinder block 1 of the hydraulic rotating machine, prescribed surface treatment is applied to a prescribed portion of a cylinder block blank 1A. The prescribed surface treatment includes: a severe plastic deformation process in which burnishing is performed on the prescribed portion of the cylinder block blank 1A to form a plastic-deformation zone layer 30 thereon; a heat treatment process in which nitriding heat treatment is performed on the plastic-deformation zone layer 30, formed by the burnishing in the severe plastic deformation process, to form a nitrogen compound layer 27 thereon; and a removing process for removing the nitrogen compound layer 27 formed by the nitriding heat treatment in the heat treatment process.

Description

  The present invention relates to a cylinder block manufacturing method and a hydraulic rotating machine for a hydraulic rotating machine provided with a cylinder block formed of spheroidal graphite cast iron.

  FIG. 12 is a view for explaining a sliding state between a piston and a cylinder provided in a conventional hydraulic rotating machine, and FIG. 13 shows a state in which the piston shown in FIG. 12 receives a centrifugal force due to rotation around a rotation axis. FIG.

  In general, a hydraulic rotary machine represented by a hydraulic pump and a hydraulic motor, for example, an axial piston pump as shown in FIG. 12, includes a rotary shaft, a cylinder block 1 that rotates as the rotary shaft rotates, And a sliding member that is in sliding contact with a predetermined sliding surface of the cylinder block 1. The sliding member includes, for example, a piston 2 housed in the cylinder 3 of the cylinder block 1 or a valve plate 4 with which the concave spherical surface portion 5 of the cylinder block 1 is in sliding contact, and the sliding surface of the cylinder 3 of the cylinder block 1 is the piston. 2 or the sliding surface of the concave spherical surface portion 5 of the cylinder block 1 slides on the valve plate 4. The cylinder block 1 is provided with a cylinder port 6A that sucks or discharges the working fluid when the piston 2 reciprocates in the cylinder 3.

  Therefore, the sliding surfaces and sliding members of the cylinder block 1 are seized or localized on the sliding surfaces due to the effect of the lubricant film running out due to the high sliding surface pressure and the instability of the sliding contact state due to fluctuations in the control oil pressure. Therefore, the cylinder block 1 and the sliding member are conventionally made of steel material, for example, spheroidal graphite cast iron (FCD) that is inexpensive and has high sliding performance among steel materials, As a constituent structure of the spheroidal graphite cast iron, ferrite or pearlite, or a coexisting structure thereof is often used.

  Here, since the cylinder block 1 is relatively large and has a higher material cost than other components, it is often made of spheroidal graphite cast iron rather than steel. However, since this spheroidal graphite cast iron has a lower surface hardness than steel, in order to increase the strength of the sliding surface of the cylinder block 1, a nitriding heat treatment is applied to a predetermined portion of the cylinder block material, and the predetermined portion is cured. By forming the predetermined sliding surface, the wear resistance performance against the sliding load applied to the cylinder block 1 is ensured.

  As one of the prior arts of the hydraulic rotating machine including the cylinder block 1 subjected to such nitriding heat treatment, the cylinder block 1 in which the inner peripheral surface of the cylinder 3 is cast iron material as it is or nitrided, and the cylinder block 1 The piston 2 is used in combination with a steel that can be nitrided, tempered to increase the substrate hardness, and subjected to nitriding treatment to form a high hardness layer among the hardened surface layers of the peripheral surface. There is known a swash plate type piston pump or motor that has been removed to leave a layer of hardness higher than the substrate hardness (see, for example, Patent Document 1).

  That is, in the prior art swash plate type piston pump or motor disclosed in Patent Document 1, a predetermined portion of a cylinder block material, for example, a cylinder 3 or a valve on which a predetermined sliding surface sliding with the piston 2 is formed. Nitrogen formed by roughing the concave spherical surface portion 5 on which a predetermined sliding surface sliding with the plate 4 is formed by cutting or grinding with a grindstone, and then subjecting the predetermined portion to nitriding heat treatment A predetermined sliding surface of the cylinder block 1 is formed by removing the compound layer by finish grinding.

  Then, when the manufactured cylinder block 1 is incorporated into a hydraulic rotating machine and rotates together with the rotating shaft, the piston 2 repeats reciprocating motion in the direction parallel to the rotating shaft in the cylinder 3, and the working fluid is supplied from the cylinder port 6A to the cylinder. Inhaled or discharged into 3. At this time, in the cylinder 3, the piston 2 strokes from the top dead center to the bottom dead center and sucks the working fluid, and the cylinder 3 strokes from the bottom dead center to the top dead center to push away the working fluid. The positive pressure due to this acts repeatedly.

  On the other hand, although the sliding surface of the cylinder 3 slides on the piston 2, a sliding load is applied to the cylinder 3. However, as described above, the wear resistance of the cylinder 3 is ensured by nitriding heat treatment. 3 seems to slide smoothly on the piston 2 without damage. However, as shown in FIG. 13, the piston 2 tilts by receiving centrifugal force by rotating around the rotation axis together with the cylinder block 1, so that the cylinder 3 and the piston 2 receive an offset load. That is, the sliding surface of the cylinder 3 slides while being in contact with the tip end portion 2a of the piston 2, and the side surface of the piston 2 is slid while being in contact with the opening end portion 3a of the cylinder 3 so as to contact them. A high sliding surface pressure acts on the part. In particular, this sliding surface pressure becomes very large in the suction process in which the piston 2 strokes from the top dead center to the bottom dead center and sucks the working fluid into the cylinder 3.

  Here, when the nitrogen compound layer formed on the cylinder block material described above was removed by finish grinding, the cylinder block material was buried in the machining area after the rough machining formation of the predetermined portion, and the cylinder was not visually recognized. Casting defects appearing on the sliding surface of the cylinder block 1 due to the opening exposure of the casting defects that existed in the surface layer region where the finish grinding is performed on the nitrogen compound layer of the block material. Thus, the manufactured cylinder block 1 is extracted as a defective product, which contributes to a decrease in manufacturing yield.

  For this reason, when a casting defect appears on the sliding surface of the cylinder 3, a pressure fluctuation caused by suction or discharge of the working fluid in the cylinder 3 causes a casting that appears on the sliding surface of the cylinder 3. A defect associated with a high sliding load acting on the sliding surface of the cylinder 3 because the crack of the defect progresses or breaks or the sliding surface of the cylinder 3 slides while being in contact with the tip 2a of the piston 2. There is a risk of abnormal wear or the like starting from the point. Therefore, there is a demand for a method for preventing casting defects from appearing on the sliding surface of the cylinder block 1 and a cylinder block from which casting defects have been removed.

  Therefore, as one of the prior arts for preventing the casting defect from appearing in the casting including the cylinder block 1, the casting defect of the casting is filled with a visible light or near-infrared light curable resin composition. A casting defect repairing method has been proposed in which the filling portion is irradiated with visible light or near infrared light to be hardened (see, for example, Patent Document 2).

JP-A-6-159230 JP 2004-50277 A

  By applying the casting defect repairing method disclosed in Patent Document 2 described above to the sliding surface portion of the cylinder block, that is, to visible defects or near-infrared light on casting defects existing on the sliding surface portion of the cylinder block. By filling the curable resin composition and irradiating the filled portion with visible light or near-infrared light to cure, the casting defects present on the sliding surface portion of the cylinder block are temporarily removed and repaired. be able to. However, since the defect repairing method of the prior art casting disclosed in Patent Document 2 is used for the non-sliding surface instead of the sliding surface, the sliding surface of the cylinder block repaired by the method is used. When the sliding member slides on the sliding member, the visible light or near infrared light curable resin composition filled in the casting defect peels and falls due to the high sliding load acting on the sliding surface of the cylinder block. There is a possibility that the fallen pieces may be caught in the sliding members of the hydraulic rotating machine. In the unlikely event that the falling pieces are bitten by the respective sliding members, the sliding members are damaged by the falling pieces, and the sliding state of each sliding member deteriorates, so that the sliding members are There are concerns about burn-in.

  The present invention has been made based on such a state of the art, and the object thereof is to realize a normal sliding state in the cylinder block and the sliding member and to maintain a stable sliding state. A cylinder block manufacturing method for a hydraulic rotating machine and a hydraulic rotating machine are provided.

  In order to achieve the above object, a cylinder block manufacturing method for a hydraulic rotating machine according to the present invention includes a rotating shaft, a cylinder block that rotates with the rotation of the rotating shaft, and is formed of spheroidal graphite cast iron. When manufacturing the cylinder block of a hydraulic rotating machine having a sliding member that is in sliding contact with a predetermined sliding surface of the cylinder block, the predetermined sliding treatment is performed by applying a predetermined surface treatment to a predetermined portion of the cylinder block material. In the cylinder block manufacturing method for a hydraulic rotating machine in which a surface is formed, the predetermined surface treatment is performed by performing high strain processing on the predetermined portion of the cylinder block material to form a plastic deformation zone layer. Nitrogen compound heat treatment is performed on the plastic deformation region layer formed by the high strain processing step and the strong strain processing in the strong strain processing step. A heat treatment step of forming the is characterized in that it comprises a removal step of removing the nitrogen compound layer formed by the nitride heat treatment in the heat treatment step.

  The present invention configured as described above exists on the surface of the predetermined portion of the cylinder block material by performing the high strain processing on the predetermined portion of the cylinder block material in the high strain processing step and forming the plastic deformation zone layer. Casting defects and casting defects that are latent inside a predetermined portion of the cylinder block material can be removed by sealing and pressing in advance by plastic deformation. As a result, a nitriding heat treatment is performed on the plastic deformation zone layer in the heat treatment process to form a nitrogen compound layer to ensure wear resistance performance at a predetermined portion of the cylinder block material, and then the nitrogen compound layer is removed in the removal process. However, it is possible to reliably suppress the occurrence of casting defects on the sliding surface of the manufactured cylinder block. Therefore, even if the sliding surface of the cylinder block slides on the sliding member, the state in which the sealing and pressure-bonding without sealing defects are maintained is maintained, and a normal sliding state in the cylinder block and the sliding member is realized. A stable sliding state can be maintained.

  The hydraulic rotating machine according to the present invention includes a rotating shaft, a cylinder block that is rotated with the rotation of the rotating shaft, and formed in spheroidal graphite cast iron, and a sliding surface that is in sliding contact with a predetermined sliding surface of the cylinder block. When manufacturing the cylinder block of the hydraulic rotating machine including the moving member, the cylinder block material includes a predetermined surface treatment process applied to a predetermined part of the cylinder block material, and the predetermined surface treatment process is performed on the predetermined part of the cylinder block material. A high strain processing step for forming a plastic deformation zone layer, and a nitriding heat treatment for the plastic deformation zone layer formed by the strong strain processing in the strong strain processing step, A liquid comprising a heat treatment step for forming a nitrogen compound layer and a removal step for removing the nitrogen compound layer formed by the nitriding heat treatment in the heat treatment step By the cylinder block manufacturing method of the rotating machine, it is characterized by comprising a cylinder block formed by subjected to a predetermined surface treatment to the predetermined portion of the cylinder block material forming said predetermined sliding surface.

  In the present invention configured as described above, the cylinder block provided in the hydraulic rotating machine forms a plastic deformation zone layer by subjecting a predetermined portion of the cylinder block material to high strain processing, and the predetermined cylinder block material Since the casting defects in the part are removed by sealing and pressure bonding, and the nitrogen compound layer is formed by performing a nitriding heat treatment on the plastic deformation zone layer, the nitrogen compound layer is removed, so the cylinder is manufactured. The surface of the sliding surface of the block and the casting defect that exists directly under the sliding surface are removed, and the hardness of the sliding surface of the cylinder block can be improved to ensure high wear resistance. Therefore, even when the hydraulic rotating machine operates and the cylinder block slides on the sliding member, it is possible to suppress casting defects on the sliding surface of the cylinder block or damage to the sliding surface. Therefore, a normal sliding state in the cylinder block and the sliding member can be realized and a stable sliding state can be maintained.

  In the hydraulic rotating machine of the present invention, in the above invention, the sliding member includes a piston, and the cylinder block includes a cylinder on which the predetermined sliding surface that slides with the piston is formed, The strong strain processing is characterized by comprising burnishing that is performed from the bottom toward the opening on the inner peripheral surface of the cylinder before the predetermined sliding surface is formed. If comprised in this way, since the inner peripheral surface of the said cylinder in which the high strain processing in a high strain processing process is performed can be plastically deformed efficiently and uniformly by burnishing, the cylinder in which the plastic deformation zone layer was formed The surface roughness of the sliding surface can be kept small. Also, the sliding surface of the cylinder in the manufactured cylinder block is subjected to a plastic deformation zone layer by applying burnishing to the opening from the bottom to the inner peripheral surface of the cylinder before the predetermined sliding surface is formed. Since each minute surface portion in the cylinder has anisotropy arranged in parallel in one direction along the opening from the bottom, the piston strokes from the top dead center to the bottom dead center in the cylinder and sucks the working fluid In this case, the resistance that the sliding surface of the cylinder receives from the piston can be reduced. As a result, the load of the sliding surface pressure generated by the sliding surface of the cylinder tilted by the centrifugal force accompanying the rotation coming into contact with the tip of the piston can be greatly reduced. The durability against the piston can be improved.

  In the hydraulic rotating machine of the present invention, in the above invention, the hydraulic rotating machine includes a hydraulic pump, the sliding member includes a valve plate, and the cylinder block slides on the valve plate. The concave spherical surface portion on which the predetermined sliding surface is formed, and the high strain processing is performed in a rotational direction of the cylinder block with respect to the surface of the concave spherical surface portion before the predetermined sliding surface is formed. It is characterized by comprising a burnishing process applied in the opposite direction. With this configuration, since the surface of the concave spherical surface portion subjected to the high strain processing in the high strain processing step can be plastically deformed efficiently and uniformly by burnishing, the concave formed with the plastic deformation zone layer is formed. The surface roughness on the sliding surface of the spherical portion can be kept small. Moreover, the sliding surface of the concave spherical portion in the manufactured cylinder block is obtained by applying burnishing to the concave spherical portion before the predetermined sliding surface is formed in the direction opposite to the rotation direction of the cylinder block. Since each fine surface part in the plastic deformation zone has anisotropy arranged in parallel in the direction opposite to the rotation direction of the cylinder block, when the hydraulic pump operates and the cylinder block rotates in a certain direction The resistance that the sliding surface of the concave spherical surface receives from the valve plate can be reduced. Thereby, the load of the sliding surface pressure generated on the sliding surface of the concave spherical portion can be greatly reduced, and the sliding performance of the sliding surface of the concave spherical portion with respect to the valve plate can be kept good.

  In the hydraulic rotary machine of the present invention, in the above invention, the sliding member comprises a valve plate, and the cylinder block has a concave spherical surface portion on which the predetermined sliding surface that slides with the valve plate is formed. The high strain processing is characterized by comprising shot peening processing performed on the surface of the concave spherical surface portion before the predetermined sliding surface is formed. With this configuration, the surface of the concave spherical surface portion subjected to the high strain processing in the high strain processing step can be efficiently and uniformly plastically deformed by shot peening, so that the entire surface of the concave spherical portion can be applied. On the other hand, the effect of work hardening by plastic deformation can be imparted effectively and quickly. Thereby, since the strength and durability of the sliding surface of the concave spherical surface portion in the manufactured cylinder block are increased, the sliding surface of the concave spherical surface portion can be smoothly slid on the valve plate over a long period of time.

  A cylinder block manufacturing method for a hydraulic rotating machine according to the present invention includes a rotating shaft, a cylinder block that is rotated with the rotation of the rotating shaft, formed of spheroidal graphite cast iron, and a predetermined sliding surface of the cylinder block. In manufacturing a cylinder block of a hydraulic rotating machine including a sliding member that is in sliding contact, a predetermined surface treatment is performed on a predetermined portion of the cylinder block material to form a predetermined sliding surface. The predetermined surface treatment is performed by a high strain processing step for forming a plastic deformation zone layer by performing high strain processing on a predetermined portion of the cylinder block material, and a strong strain processing in the strong strain processing step. A heat treatment step of performing a nitriding heat treatment on the plastic deformation region layer to form a nitrogen compound layer, and a removing step of removing the nitrogen compound layer formed by the nitriding heat treatment in this heat treatment step. For this reason, a predetermined portion of the cylinder block material is sealed and pressure-bonded by high strain processing to remove casting defects existing in the predetermined portion, so that when the nitrogen compound layer formed by nitriding heat treatment is removed, the high strain processing It is possible to suppress the occurrence of casting defects that have been hidden inside a predetermined portion of the cylinder block material before performing the process, and to improve the sliding performance of the cylinder block. Thereby, it is possible to stably produce a cylinder block of spheroidal graphite cast iron with fewer defects on the sliding surface than in the past, and to improve the production yield of the cylinder block.

  As described above, the hydraulic rotary machine including the cylinder block manufactured by the cylinder block manufacturing method of the hydraulic rotary machine according to the present invention has a sliding surface of the cylinder block that slides on the sliding member during operation. Since a state free from casting defects that has been sealed by pressure is maintained, it is possible to achieve a normal sliding state in the cylinder block and the sliding member and to maintain a stable sliding state. Therefore, since the occurrence of damage or breakage in the cylinder block and the sliding member can be greatly reduced as compared with the prior art, high reliability for the hydraulic rotating machine can be obtained.

1 is a diagram illustrating a configuration of a variable displacement swash plate type axial piston pump that is a first embodiment of a hydraulic rotating machine according to the present invention. FIG. It is a figure explaining the state of the internal peripheral surface of the cylinder with which 1st Embodiment of the cylinder block manufacturing method of the hydraulic rotating machine which concerns on this invention is applied. It is a figure which shows the state in which the nitrogen compound layer was formed in the internal peripheral surface of the cylinder shown in FIG. It is a figure explaining the strong strain processing process in 1st Embodiment of the cylinder block manufacturing method of the hydraulic rotating machine which concerns on this invention. It is a figure explaining the heat treatment process and removal process in a 1st embodiment of a cylinder block manufacturing method of a hydraulic rotating machine concerning the present invention. It is a figure explaining the sliding surface of the cylinder in 1st Embodiment of the hydraulic rotating machine which concerns on this invention. It is a figure explaining the strong strain processing process in 2nd Embodiment of the cylinder block manufacturing method of the hydraulic rotating machine which concerns on this invention. It is a figure explaining the surface state of the concave spherical surface part of the cylinder block to which 3rd Embodiment of the cylinder block manufacturing method of the hydraulic rotating machine which concerns on this invention is applied. It is a figure explaining the strong strain processing process in 3rd Embodiment of the cylinder block manufacturing method of the hydraulic rotating machine which concerns on this invention. It is a figure explaining the sliding surface of the concave spherical surface part in 3rd Embodiment of the hydraulic rotating machine which concerns on this invention. It is a figure explaining the strong strain processing process in 4th Embodiment of the cylinder block manufacturing method of the hydraulic rotating machine which concerns on this invention. It is a figure explaining the sliding state of the piston and cylinder with which the conventional hydraulic rotating machine was equipped. It is a figure which shows the state which the piston shown in FIG. 12 received the centrifugal force by the rotation around a rotating shaft.

  Hereinafter, a cylinder block manufacturing method of a hydraulic rotating machine and a form for carrying out the hydraulic rotating machine concerning the present invention are explained based on figures.

[First Embodiment of Hydraulic Rotating Machine]
The basic configuration of the first embodiment of the hydraulic rotating machine according to the present invention is the same as the configuration of the hydraulic rotating machine shown in FIG. Therefore, the same reference numerals are given to the portions overlapping with the hydraulic rotating machine shown in FIG.

  The hydraulic rotary machine according to the first embodiment of the present invention is provided in, for example, a variable displacement swash plate type axial piston pump. As shown in FIG. 1, a variable displacement swash plate type axial piston pump, that is, a hydraulic pump 7 includes a casing 8 that forms an outer shell, and a rotary shaft 9 that is rotatably provided around an axis at the center of the casing 8. And a cylinder block 1 that is rotated by the rotation of the rotary shaft 9 and is formed of spheroidal graphite cast iron; a sliding member that is in sliding contact with a predetermined sliding surface of the cylinder block 1; A plurality of pistons 2 accommodated in each cylinder 3 are provided. Here, in 1st Embodiment of the hydraulic rotating machine of this invention, a sliding member consists of each piston 2 mentioned above, for example, 1st Embodiment of the cylinder block manufacturing method of the hydraulic rotating machine which concerns on this invention, In manufacturing the cylinder block 1 of the hydraulic pump 7, a predetermined surface treatment is applied to a predetermined portion of the cylinder block material 1A, for example, a portion corresponding to the cylinder 3, as shown in FIGS. A surface is formed.

  In the first embodiment of the hydraulic rotating machine of the present invention, the casing 8 includes a cylindrical casing body 12 that covers each member such as the rotating shaft 9 and the cylinder block 1, and a front that closes both ends of the casing body 12. It consists of a casing 13 and a rear casing 14. The rear casing 14 has a pair of supply / discharge passages 15 </ b> A and 15 </ b> B through which hydraulic oil is supplied to or discharged from the cylinder block 1. These supply / discharge passages 15A and 15B are connected to piping (not shown) or the like provided on the suction side and the discharge side of the hydraulic oil.

  The rotary shaft 9 is rotatably supported between the front casing 13 and the rear casing 14 via bearings 16 and 17 and the like. Further, the rotating shaft 9 is formed with a protruding end 9A protruding in the axial direction from the front casing 13, and the protruding end 9A side is rotationally driven by a motor (not shown) such as a diesel engine. The cylinder block 1 is splined to the outer peripheral side of the rotating shaft 9 and rotates together with the rotating shaft 9. The cylinder block 1 is arranged such that one end on the front casing 13 side of both end faces is opposed to a swash plate 11 described later, and the other end on the rear casing 14 side of both end faces is in sliding contact with a valve plate 4 described later. .

  The cylinder block 1 includes the above-described plurality of cylinders 3 including the pistons 2 therein, and the cylinders 3 are spaced apart from each other around the axis of the cylinder block 1 around the rotation shaft 9. And arranged parallel to the axial direction of the cylinder block 1, that is, the axial direction of the rotary shaft 9. A cylinder port 6A is formed at one end of each cylinder 3 so as to intermittently communicate with or shut off the supply / discharge passages 15A and 15B of the rear casing 14 via a valve plate 4 described later.

  The hydraulic pump 7 is swingably held at the end of each piston 2 and provided with a plurality of shoes 10 that rotate together with the cylinder block 1 and the front casing 13 of the casing 8 so as to be tiltable. A swash plate 11 slidably contacting each shoe 10, a plurality of shoe pressers 18 that respectively press each shoe 10 against the swash plate 11 by the pressing force of each piston 2, and a front casing 13 are provided to swing the swash plate 11. A tilting actuator that tilts and drives the swash plate 11 and a cradle 20 that is supported, a valve plate 4 that is disposed on the rear casing 14 side of the casing 8 and is provided between the rear casing 14 and the cylinder block 1. 23, 24.

  The swash plate 11 is fixedly provided on the surface side of the swash plate main body 22 supported by the cradle 20 so as to be tiltable, a smooth plate 19 on which the shoe 10 slides, and the rotary shaft 9. It consists of the shaft insertion hole 22A which penetrates. The size of the shaft insertion hole 22 </ b> A is set so that the rotation shaft 9 does not hinder the tilting operation of the swash plate 11 when the rotation shaft 9 is inserted. The smooth plate 19 has a shaft insertion hole 19A through which the central portion is hollowed and the rotation shaft 9 is inserted, like the shaft insertion hole 22A, and is formed in a donut-shaped disk shape.

  The cradle 20 is disposed on the back side of the swash plate 11 and is fixed to the front casing 13 of the casing 8. In addition, the cradle 20 is provided with a pair of tilting sliding surfaces 2 that are separated from each other left and right or up and down with the rotating shaft 9 interposed therebetween. The tilting sliding surfaces 2 can tilt the swash plate 11. It is formed in the concave curved circular arc surface so that it may support. And the swash plate main body 22 is attached to the front casing 13 side via the tilt sliding surface 2 of the cradle 20 so that tilting is possible. Further, the tilt actuators 23 and 24 control the tilt angle of the swash plate 11 variably according to the tilt control pressure by supplying and discharging the tilt control pressure from the outside.

  Each shoe 10 is held in a state of being pressed against the smooth plate 19 of the swash plate 11 via the shoe presser 18 and the like by the pressing force from each piston 2. The valve plate 4 is in sliding contact with the end surface on the rear casing 14 side of both end surfaces of the cylinder block 1, and supports the cylinder block 1 together with the rotary shaft 9 so as to be rotatable. The valve plate 4 is formed with a pair of supply / discharge ports 4A having an eyebrow shape, and these supply / discharge ports 4A communicate with supply / discharge passages 15A, 15B of the rear casing 14 so that the cylinder block 1 When rotating around the axis of the rotary shaft 9, the cylinder port 6 </ b> A of each cylinder 3 is intermittently communicated.

  Here, when the rotary shaft 9 is rotationally driven by a prime mover such as an engine, the cylinder block 1 rotates integrally with the rotary shaft 9 around the axis of the rotary shaft 9 in a certain direction. At this time, since the swash plate 11 is tilted with respect to the casing body 12 by the tilt actuators 23 and 24, the piston 2 accommodated in the cylinder 3 of the cylinder block 1 moves to the cylinder as the cylinder block 1 rotates. The suction process in which the inside of the cylinder 3 slides from the top dead center to the bottom dead center and the discharge process in which the inside of the cylinder 3 slides from the bottom dead center to the top dead center are repeated. Accordingly, in the piston 2 suction process, for example, hydraulic oil is sucked into the cylinder 3 from the supply / discharge passage 15B, and in the piston 2 discharge process, the hydraulic oil is discharged from the cylinder 3 to the supply / discharge passage 15A as high pressure oil. Is done. Since the stroke length of the piston 2 is increased or decreased according to the tilt angle of the swash plate 11 with respect to the axis of the rotary shaft 9, the tilt actuators 23 and 24 control the tilt angle of the swash plate 11 to change the cylinder. The suction amount and discharge amount of the hydraulic oil in 3 are adjusted.

  Next, the above-described cylinder block 1 provided in the hydraulic pump 7 is formed as follows, for example.

  FIG. 2 is a view for explaining the state of the inner peripheral surface of the cylinder to which the first embodiment of the cylinder block manufacturing method for a hydraulic rotating machine according to the present invention is applied, and FIG. 3 is the inner peripheral surface of the cylinder shown in FIG. The figure which shows the state in which the nitrogen compound layer was formed, FIG. 4 is a figure explaining the strong strain processing process in 1st Embodiment of the cylinder block manufacturing method of the hydraulic rotating machine which concerns on this invention, FIG. 5 concerns on this invention The figure explaining the heat treatment process and removal process in 1st Embodiment of the cylinder block manufacturing method of a hydraulic rotating machine, FIG. 6: demonstrates the sliding surface of the cylinder in 1st Embodiment of the hydraulic rotating machine which concerns on this invention. FIG.

  1st Embodiment of the cylinder block manufacturing method of the hydraulic rotating machine which concerns on this invention forms the outer diameter of 1 A of cylinder block raw materials, as shown in FIG. 2, by cutting the spheroidal graphite cast iron which is a raw material, for example. . At this time, a casting defect 25 exists on the surface of a predetermined portion of the cylinder block material 1A, for example, an inner peripheral surface portion of the cylinder 3A before the predetermined sliding surface is formed, and the casting defect 26 also exists inside. Latent. Therefore, according to the first embodiment of the cylinder block manufacturing method of the present invention, the predetermined surface treatment described above is performed by subjecting the inner peripheral surface of the cylinder 3A to high strain processing as shown in FIGS. A high strain processing step for forming the deformation zone layer 30, and a heat treatment step for forming a nitrogen compound layer 27 by performing nitriding heat treatment on the plastic deformation zone layer 30 formed by the high strain processing in the high strain processing step. And a removing step of removing the nitrogen compound layer 27 formed by the nitriding heat treatment in this heat treatment step.

  Specifically, in the high strain processing step, as shown in FIG. 3, when the surface portion of the plastic deformation zone layer 30 is removed in addition to the nitrogen compound layer 27 in the removing step described later, that is, the surface of the nitrogen compound layer 27. When removing from the depth A to the depth A, the high strain processing is sufficiently performed on the inner peripheral surface in the high strain processing step so that the casting defect 26 latent in the inner peripheral surface portion of the cylinder 3A is not exposed.

  The high strain processing in the first embodiment of the cylinder block manufacturing method of the present invention comprises, for example, burnishing that is performed from the bottom to the opening on the inner peripheral surface portion of the cylinder 3A as shown in FIG. In this burnishing process, for example, a shaft 28a having an outer diameter smaller than the inner diameter of the cylinder 3A, and a plurality of cylindrical rolling elements 28b provided on the outer peripheral surface of the shaft 28a at regular intervals around the axis. A roller burnishing tool 28 is used.

  When the roller burnishing tool 28 is inserted inwardly from the opening of the cylinder 3A and each roller 28b is pressed against the inner peripheral surface of the bottom of the cylinder 3A to rotate the shaft 28a, each roller 28b is moved to the inner periphery of the cylinder 3A. Since the surface rolls while pressurizing the surface, the surface texture of the inner peripheral surface of the pressurized cylinder 3A plastically flows. Therefore, each rolling element 28b seals the casting defect 25 existing on the inner peripheral surface of the cylinder 3A, and the casting defect 26 latent inside the inner peripheral surface portion of the cylinder 3A is also crushed and pressed. These casting defects 25 and 26 are removed.

  Accordingly, as shown in FIG. 5, the roller burnishing tool 28 is lifted from the bottom of the cylinder 3A to the opening, that is, in the direction of the arrow B in a state where each rolling element 28b pressurizes the inner peripheral surface of the bottom of the cylinder 3A. A plastic deformation zone 30 is formed on the inner peripheral surface portion of the cylinder 3A. At this time, each rolling element 28b of the roller burnishing tool 28 slides from the bottom along the opening to the inner peripheral surface of the cylinder 3A, so that the fine deformation region layer 30 formed as shown in FIG. Each surface portion 30a is arranged in parallel from one bottom to one direction along the opening.

  Next, in the heat treatment step, when nitriding heat treatment is performed on the plastic deformation region layer 30 formed by the high strain processing in the above-described strong strain processing step, the surface of the plastic deformation region layer 30 is formed as shown in FIG. A nitrogen compound layer 27 is formed. Since the nitrogen compound layer 27 is hard and brittle, if the nitrogen compound layer 27 is not sufficiently removed in the removal process, the nitrogen compound layer 27 remaining in the cylinder 3A slides on the piston 2 and is lost. Then, there is a possibility that the piston 2 and the like are damaged by the broken pieces of the nitrogen compound layer 27 that are missing. In order to prevent this, the nitrogen compound layer 27 on the surface of the plastic deformation zone layer 30 needs to be completely removed in the removing step.

  Therefore, in the removing process, not only the range in which the nitrogen compound layer 27 on the inner peripheral surface of the cylinder 3A is formed as shown in FIG. The thickness of the nitrogen compound layer 27 is exceeded, and the plastic deformation zone layer 30 formed immediately below the layer is ground and removed. That is, grinding is performed from the surface of the nitrogen compound layer 27 to the depth A, and the nitrogen compound layer 27 is completely removed as shown in FIG.

  According to 1st Embodiment of the cylinder block manufacturing method of the hydraulic rotating machine which concerns on this invention comprised in this way, a high strain process is performed with respect to the internal peripheral surface of the cylinder 3A in a strong strain process, and a plastic deformation area | region is carried out. By forming the layer 30, the casting defect 25 existing on the inner peripheral surface of the cylinder 3 </ b> A and the casting defect 26 existing inside the inner peripheral surface portion of the cylinder 3 </ b> A are removed by sealing and pressing in advance by plastic deformation. be able to. Then, a nitriding heat treatment is performed on the plastic deformation zone layer 30 in the heat treatment step to form the nitrogen compound layer 27 to ensure wear resistance performance on the inner peripheral surface portion of the cylinder 3A, and then the nitrogen compound layer 27 in the removal step. By grinding from the surface to the depth A, it is possible to reliably prevent the casting defects 25 and 26 from appearing on the sliding surface of the cylinder 3 in the manufactured cylinder block 1. Further, as shown in FIG. 6, since the nitrogen compound layer 27 does not remain on the sliding surface of the cylinder 3, the effect of wear resistance on the inner peripheral surface portion of the cylinder 3A obtained by nitriding heat treatment is sufficiently exhibited. can do. Thereby, the cylinder block 1 of spheroidal graphite cast iron with few defects can be stably manufactured on the sliding surface, and the manufacturing yield of the cylinder block 1 can be improved.

  And in 1st Embodiment of the hydraulic rotary machine provided with the cylinder block 1 manufactured by 1st Embodiment of the cylinder block manufacturing method of this invention, the sliding surface of the cylinder 3 in the cylinder block 1 is piston during operation | movement. 2 is maintained without the casting defects 25 and 26 being sealed and sealed, so that a normal sliding state is achieved in the cylinder 3 and the piston 2 and a stable sliding state is maintained. can do. Therefore, since the occurrence of damage or breakage in the cylinder 3 and the piston 2 can be greatly reduced, high reliability for the hydraulic pump 7 can be obtained.

  In the first embodiment of the cylinder block manufacturing method of the present invention, the inner peripheral surface of the cylinder 3A is subjected to burnishing on the inner peripheral surface of the cylinder 3A using the roller burnishing tool 28 in the high strain processing step. Since the entire surface can be efficiently and uniformly plastically deformed by burnishing, the surface roughness of the sliding surface of the cylinder 3 in the manufactured cylinder block 1 can be kept small. Further, in the burnishing process, each rolling element 28b of the roller burnishing tool 28 is pressed against the inner peripheral surface of the cylinder 3A to roll, and the roller burnishing tool 28 is lifted from the bottom toward the opening with respect to the inner peripheral surface of the cylinder 3A. Thus, the sliding surface of the cylinder 3 in the manufactured cylinder block 1 is arranged in parallel so that each fine surface portion 30a in the plastic deformation zone layer 30 faces one direction from the bottom to the opening as shown in FIG. Therefore, when the piston 2 strokes from the top dead center to the bottom dead center in the cylinder 3 and sucks hydraulic oil, the resistance that the sliding surface of the cylinder 3 receives from the piston 2 is reduced. be able to. Thereby, the load of the sliding surface pressure generated when the sliding surface of the cylinder 3 tilted by the centrifugal force accompanying the rotation hits the front end portion 2a of the piston 2 can be greatly reduced. The durability of the sliding surface with respect to the piston 2 can be improved.

[Second Embodiment of Hydraulic Rotating Machine]
FIG. 7 is a diagram for explaining the high strain processing step in the second embodiment of the cylinder block manufacturing method for a hydraulic rotating machine according to the present invention.

  The second embodiment of the cylinder block manufacturing method of the hydraulic rotating machine according to the present invention is different from the above-described first embodiment of the cylinder block manufacturing method in the first embodiment, as shown in FIG. In contrast to the high strain processing in the process, which consists of burnishing performed from the bottom to the opening on the inner peripheral surface of the cylinder 3A before the cylinder 3 is formed, in the second embodiment, FIG. As shown in FIG. 5, the high strain processing in the high strain processing step is, for example, a shot peening processing performed on the inner peripheral surface of the cylinder 3A.

  Specifically, the high strain processing in the second embodiment of the cylinder block manufacturing method of the present invention has a nozzle having an outer diameter smaller than the inner diameter of the cylinder 3, for example, in shot peening, and ejects hard particles 32 by compressed air. 31A is used. The nozzle 31A is inserted inward from the opening of the cylinder 3A, and the ejected hard particles 32 are moved into the cylinder 3A by rotating the nozzle 31A around the axis while moving the nozzles 31A up and down while ejecting the hard particles 32 from the tip. Colliding with the inner peripheral surface, the surface structure of the inner peripheral surface of the cylinder 3A plastically flows. Therefore, the casting defect 25 existing on the inner peripheral surface of the cylinder 3A is sealed by the hard particles 32, and the casting defect 26 latent inside the inner peripheral surface portion of the cylinder 3A is also crushed and pressed. These casting defects 25 and 26 are removed.

  Therefore, in the second embodiment of the hydraulic rotating machine according to the present invention, the above-described predetermined surface treatment processing is applied to the inner peripheral surface of the cylinder 3A by the second embodiment of the cylinder block manufacturing method of the present invention, and the predetermined sliding treatment is performed. A cylinder block 1 formed with a moving surface is provided. The sliding surface of the cylinder 3 in the second embodiment of the hydraulic rotating machine of the present invention is such that each fine surface portion 30a in the plastic deformation zone layer 30 formed in the first embodiment of the hydraulic rotating machine is the bottom. There is no anisotropy arranged side by side in one direction along the opening. Other configurations are the same as those of the first embodiment.

  According to the second embodiment of the hydraulic rotating machine of the present invention configured as described above, the inner peripheral surface of the cylinder 3A subjected to high strain processing in the high strain processing step is efficiently and evenly plasticized by shot peening processing. Since it can be deformed, the casting defects 25 and 26 existing in the inner peripheral surface portion of the cylinder 3A can be efficiently removed, and the effect of work hardening by plastic deformation can be effectively performed on the entire inner peripheral surface of the cylinder 3A. It can be granted quickly. Accordingly, the sliding surface of the cylinder 3 in the second embodiment of the hydraulic rotating machine of the present invention has greatly improved strength and durability by the shot peening process, so that it has a stable sliding performance over a long period of time. Can be maintained.

[Third embodiment of hydraulic rotating machine]
FIG. 8 is a view for explaining the surface state of the concave spherical surface portion of the cylinder block to which the third embodiment of the cylinder block manufacturing method of the hydraulic rotary machine according to the present invention is applied, and FIG. 9 is a hydraulic rotary machine according to the present invention. FIG. 10 is a diagram for explaining the sliding surface of the concave spherical surface portion in the third embodiment of the hydraulic rotating machine according to the present invention. .

  The third embodiment of the cylinder block manufacturing method of the hydraulic rotating machine according to the present invention is different from the first embodiment of the cylinder block manufacturing method described above. In the first embodiment, the sliding member is composed of each piston 2. As shown in FIG. 4, the high strain processing in the high strain processing step is composed of burnishing performed from the bottom to the opening on the inner peripheral surface of the cylinder 3A before the cylinder 3 is formed. On the other hand, in the third embodiment, the sliding member is composed of, for example, the valve plate 4, and the concave spherical portion before the predetermined sliding surface is formed, for example, as shown in FIG. It consists of a burnishing process performed in the direction opposite to the rotation direction of the cylinder block 1 with respect to the surface of 5A.

  Specifically, the high strain processing in the third embodiment of the cylinder block manufacturing method of the present invention includes a disc 34c formed with a curved surface portion 34c1 facing the concave spherical surface portion 5A in the burnishing processing, and the disc 34c. A shaft 34a provided perpendicularly to the disk 34c at the center of the surface opposite to the curved surface portion 34c1, and provided on the curved surface portion 34c1 of the disk 34c at a certain interval around the central axis of the disk 34c. A roller burnishing tool 34 comprising a plurality of cylindrical rolling elements 34b is used.

  When the curved surface portion 34c1 of the roller burnishing tool 34 is pressed against the concave spherical surface portion 5A and the shaft 34a is rotated in the direction opposite to the rotation direction of the cylinder block 1, that is, in the direction of arrow C, each rolling element 34b becomes the surface of the concave spherical surface portion 5A. , The surface texture of the pressed concave spherical surface portion 5A plastically flows. Therefore, the casting defect 25 existing on the surface of the concave spherical surface portion 5A shown in FIG. 8 is sealed by each rolling element 34b, and the casting defect 26 latent inside the concave spherical surface portion 5A is also crushed and pressure-bonded. Therefore, these casting defects 25 and 26 are removed as shown in FIG. In addition, although not shown in the figure, each of the rolling elements 34b of the roller burnishing tool 34 slides toward the concave spherical surface portion 5A in the direction opposite to the rotation direction of the cylinder block 1; Each surface portion is arranged side by side in the direction opposite to the rotation direction of the cylinder block 1.

  In the third embodiment of the hydraulic rotating machine according to the present invention, the surface of the concave spherical surface portion 5A is subjected to the above-described predetermined surface treatment by the third embodiment of the cylinder block manufacturing method of the present invention, and the predetermined sliding treatment is performed. A cylinder block 1 formed with a moving surface is provided. Other configurations are the same as those of the first embodiment.

  According to the third embodiment of the hydraulic rotating machine of the present invention configured as described above, the surface of the concave spherical surface portion 5A subjected to high strain processing in the high strain processing step is efficiently and uniformly plastically deformed by burnishing. Therefore, the surface roughness on the sliding surface of the concave spherical surface portion 5A on which the plastic deformation zone layer 30 is formed can be kept small. Also, the cylinder block 1 manufactured by pressing the curved surface portion 34c1 of the roller burnishing tool 34 against the concave spherical surface portion 5A and rotating the shaft 34a in the direction opposite to the rotation direction of the cylinder block 1, that is, in the direction of arrow C in the burnishing process. Since the sliding surface of the concave spherical surface portion 5 has anisotropy in which fine surface portions of the plastic deformation zone layer 30 are arranged in parallel in the direction opposite to the rotation direction of the cylinder block 1, the hydraulic pump 7 When the cylinder block 1 operates and rotates in a certain direction, the resistance received by the sliding surface of the concave spherical surface portion 5 from the valve plate 4 can be reduced. Thereby, the load of the sliding surface pressure generated on the sliding surface of the concave spherical surface portion 5 can be greatly reduced, and the sliding performance of the sliding surface of the concave spherical surface portion 5 with respect to the valve plate 4 can be kept good. it can.

[Fourth Embodiment of Hydraulic Rotating Machine]
FIG. 11 is a diagram for explaining the high strain processing step in the fourth embodiment of the cylinder block manufacturing method for a hydraulic rotating machine according to the present invention.

  The fourth embodiment of the cylinder block manufacturing method of the hydraulic rotating machine according to the present invention is different from the first embodiment of the cylinder block manufacturing method described above. In the first embodiment, the sliding member is composed of each piston 2. As shown in FIG. 4, the high strain processing in the high strain processing step is composed of burnishing performed from the bottom to the opening on the inner peripheral surface of the cylinder 3A before the cylinder 3 is formed. On the other hand, in the fourth embodiment, the sliding member is made of, for example, the valve plate 4 and, as shown in FIG. 11, the strong strain processing in the high strain processing step, for example, the concave spherical surface portion before the predetermined sliding surface is formed. It consists of shot peening applied to the surface of 5A.

  Specifically, the high strain processing in the fourth embodiment of the cylinder block manufacturing method of the present invention uses a nozzle 31B that injects hard particles 32 by, for example, compressed air in shot peening processing. By injecting the hard particles 32 from the tip with the nozzle 31B facing the surface of the concave spherical portion 5A, the injected hard particles 32 collide with the surface of the concave spherical portion 5A, and the surface structure of the concave spherical portion 5A is plastic. To flow. Therefore, the casting defect 25 existing on the surface of the concave spherical portion 5A is sealed by the hard particles 32, and the casting defect 26 latent inside the concave spherical portion 5A is also crushed and pressure-bonded. Defects 25 and 26 are removed.

  Therefore, in the fourth embodiment of the hydraulic rotating machine according to the present invention, the above-described predetermined surface treatment is performed on the surface of the concave spherical surface portion 5A according to the fourth embodiment of the cylinder block manufacturing method of the present invention. A cylinder block 1 formed with a sliding surface is provided. In addition, the sliding surface of the concave spherical surface portion 5A in the fourth embodiment of the hydraulic rotating machine of the present invention is each minute surface in the plastic deformation zone layer 30 formed in the third embodiment of the hydraulic rotating machine described above. The portion does not have anisotropy arranged side by side in the direction opposite to the rotation direction of the cylinder block 1. Other configurations are the same as those of the first embodiment.

  According to the fourth embodiment of the hydraulic rotating machine of the present invention configured as described above, the surface of the concave spherical surface portion 5A subjected to high strain processing in the high strain processing step is efficiently and evenly plasticized by shot peening processing. Since it can be deformed, the effect of work hardening by plastic deformation can be effectively and quickly applied to the entire surface of the concave spherical surface portion 5A. Therefore, the sliding surface of the concave spherical surface portion 5 in the fourth embodiment of the hydraulic rotating machine of the present invention can greatly increase the wear resistance, so that it is worn out by sliding on the valve plate 4. Therefore, a smooth sliding motion can be maintained for a long time.

  The second and fourth embodiments of the method of manufacturing a cylinder block for a hydraulic rotating machine according to the present invention described above are hard particles by compressed air in shot peening processing in a high strain processing step as shown in FIGS. Although the case where the nozzles 31 </ b> A and 31 </ b> B for injecting the nozzles 32 are used has been described, the present invention is not limited to this case.

  In the first to fourth embodiments of the cylinder block manufacturing method for a hydraulic rotating machine according to the present invention, a predetermined surface treatment is performed on either one of the inner peripheral surface of the cylinder 3A and the surface of the concave spherical surface portion 5A. However, the present invention is not limited to this case, and the cylinder block may be manufactured by applying a predetermined surface treatment to both the inner peripheral surface of the cylinder 3A and the surface of the concave spherical surface portion 5A.

DESCRIPTION OF SYMBOLS 1 Cylinder block 1A Cylinder block material 2 Piston 2a Tip part 3, 3A Cylinder 3a Open end part 4 Valve plate 5, 5A Concave spherical part 7 Hydraulic pump 9 Rotating shaft 11 Swash plate 25, 26 Casting defect 26 Potential defect 27 Nitrogen compound layer 28, 34 Roller burnishing tool 28a, 34a Shaft 28b, 34b Roller 30 Plastic deformation zone 30a Surface portion 31A, 31B Nozzle 32 Hard particles 34c Disk 34c1 Curved surface

Claims (5)

A hydraulic rotating machine comprising a rotating shaft, a cylinder block that is rotated by the rotation of the rotating shaft and is formed of spheroidal graphite cast iron, and a sliding member that is in sliding contact with a predetermined sliding surface of the cylinder block In manufacturing the cylinder block, a cylinder block manufacturing method for a hydraulic rotating machine in which a predetermined surface treatment is performed on a predetermined portion of a cylinder block material to form the predetermined sliding surface.
The predetermined surface treatment is
A high strain processing step of performing a high strain processing on the predetermined portion of the cylinder block material to form a plastic deformation zone layer,
A nitriding heat treatment is performed on the plastic deformation region layer formed by the high strain processing in the strong strain processing step, and a nitrogen compound layer is formed,
And a removing step of removing the nitrogen compound layer formed by the nitriding heat treatment in the heat treatment step.   A hydraulic rotating machine comprising a rotating shaft, a cylinder block that is rotated by the rotation of the rotating shaft and is formed of spheroidal graphite cast iron, and a sliding member that is in sliding contact with a predetermined sliding surface of the cylinder block In the manufacture of the cylinder block, a predetermined surface treatment process is performed on a predetermined part of the cylinder block material. The predetermined surface treatment process performs a high strain process on the predetermined part of the cylinder block material and performs plastic deformation. A high strain processing step for forming a region layer, a heat treatment step for performing a nitriding heat treatment on the plastic deformation region layer formed by the high strain processing in the strong strain processing step to form a nitrogen compound layer, and A cylinder block of a hydraulic rotating machine including a removal step of removing the nitrogen compound layer formed by the nitriding heat treatment in a heat treatment step By the way, hydraulic rotary machine, characterized in that it includes a cylinder block formed by subjected to a predetermined surface treatment to the predetermined portion of the cylinder block material forming said predetermined sliding surface. In the hydraulic rotating machine according to claim 2,
The sliding member comprises a piston;
The cylinder block has a cylinder in which the predetermined sliding surface that slides with the piston is formed,
The strong strain processing is
A hydraulic rotating machine comprising a burnishing process applied from the bottom to the opening on the inner peripheral surface of the cylinder before the predetermined sliding surface is formed. In the hydraulic rotating machine according to claim 2,
The hydraulic rotating machine is composed of a hydraulic pump,
The sliding member comprises a valve plate,
The cylinder block has a concave spherical surface portion on which the predetermined sliding surface sliding with the valve plate is formed,
The strong strain processing is characterized by comprising burnishing that is performed in a direction opposite to the rotation direction of the cylinder block with respect to the surface of the concave spherical portion before the predetermined sliding surface is formed. Hydraulic rotating machine. In the hydraulic rotating machine according to claim 2,
The sliding member comprises a valve plate,
The cylinder block has a concave spherical surface portion on which the predetermined sliding surface sliding with the valve plate is formed,
The hydraulic rotating machine is characterized by comprising a shot peening process performed on the surface of the concave spherical surface portion before the predetermined sliding surface is formed.

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