JP6136160B2 - Cylinder bore inner surface processing method and cylinder structure - Google Patents

Description

The present invention relates to a construction technique for an inner surface of a cylinder bore in a cylinder block of an internal combustion engine, and more particularly, an improvement in seizure resistance and wear resistance of the inner surface of the cylinder bore and good sliding characteristics corresponding to a sliding stroke part. The present invention relates to a processing method and a cylinder structure .

  In general, a cylinder block of an internal combustion engine is provided with an uneven shape in order to prevent seizure and abnormal wear due to running out of lubricating oil on the inner surface of the cylinder bore during actual operation. By forming a concave and convex portion on the inner surface of the cylinder bore and providing a mechanism for retaining lubricating oil in the concave portion, burning and seizure of the inner surface of the cylinder bore and abnormal wear are prevented.

  However, depending on the degree of unevenness on the inner surface of the cylinder bore, the piston slidability is lowered, the piston behavior becomes unstable, and the frictional resistance is increased. In order to prevent seizure, burnout, and abnormal wear of the cylinder bore inner surface, construction techniques for the cylinder bore inner surface having excellent seizure resistance, wear resistance and sliding characteristics have been developed as shown in Patent Documents 1 and 2. Yes.

  The engine described in Patent Document 1 has a difference in surface roughness between the piston (both) thrust side of the cylinder bore inner surface and the cylinder bore inner surface of a circumferential portion orthogonal to the (both) thrust side. And, by constructing the surface roughness of the cylinder bore inner surface in the sliding stroke direction on the (both) thrust side smaller than the circumferential part orthogonal to each other, the behavior on the (both) thrust side during piston sliding is stabilized and low friction is achieved. Is configured. The engine oil is supplied to both thrust sides from the concave part of the circumferential part with a large surface roughness to prevent seizure and abnormal wear due to running out of lubricating oil on the piston (both) thrust side and cylinder bore inner surface. Yes.

  In addition, in the invention described in Patent Document 2, in addition to coating the inner surface of a mirror-finished cylinder bore with a low friction / hard coating such as DLC (Diamond-Like Carbon) in the piston sliding stroke direction, This is a construction technique for the inner surface of the cylinder bore that forms a recess that becomes a lubricating oil path on the inner surface of the cylinder bore by masking.

JP-A-2005-90442 JP 2011-220151 A

  In the conventional construction technique, since the uneven portion having a large surface roughness is provided in the portion corresponding to the top and bottom dead centers (of the piston) on the inner surface of the cylinder bore, the lubricating oil tends to stay in the recess on the combustion chamber side of the inner surface of the cylinder bore. In addition, the blow-by gas is also difficult to pass to the crankcase side, and there is a concern that both the oil consumption and the blow-by gas increase.

  In order to suppress oil consumption, etc., it is necessary to reduce the surface roughness of the upper and lower dead centers corresponding to the inner surface of the cylinder bore as much as possible. It is a place that is easily deficient. If the cylinder bore inner surface itself does not have sufficient surface hardness, it will cause adhesion between sliding parts such as pistons and piston rings, making it difficult to ensure seizure resistance and wear resistance. It was.

  Further, in the invention described in Patent Document 1, since the difference in surface roughness is provided in the circumferential direction on the inner surface of the cylinder bore, the behavior of the piston ring is disturbed and the sliding resistance increases instead. In the invention described in Document 2, there is a problem that expensive mirror surface processing and coating work are required, and the processing cost is expensive.

  Furthermore, in the prior art, in addition to realizing low friction and securing seizure resistance and wear resistance on the inner surface of the cylinder bore, there is a problem that it is difficult to simultaneously reduce oil consumption and blow-by gas amount.

The present invention has been made in consideration of the above-described circumstances, and improves seizure resistance and wear resistance on the inner surface of the cylinder bore and ensures good sliding characteristics, and suppresses an increase in oil consumption and blow-by gas amount. An object of the present invention is to provide a cylinder bore inner surface machining method and a cylinder structure .

In order to achieve the above-described object, the present invention provides a method for processing an inner surface of a cylinder bore in which a plating film is formed on an inner surface of an aluminum alloy cylinder bore, and the first portion corresponding to the piston vertical dead center equivalent portion of the inner surface of the cylinder bore is limited. And a honing grinding process for grinding a plating film on the inner surface of the cylinder bore cured by the heat treatment.
Further, in order to achieve the above-mentioned object, the present invention provides a cylinder bore inner surface processing method in which a plating film is formed on an aluminum alloy cylinder bore inner surface, wherein a first portion corresponding to a piston vertical dead center equivalent portion of the cylinder bore inner surface is provided. A heat treatment step for heat treatment, a step of performing heat control on the second portion other than the first portion on the inner surface of the cylinder bore for cooling control while heat-treating the first portion on the inner surface of the cylinder bore, and the heating And a honing grinding step for grinding a plating film on the inner surface of the cylinder bore hardened by the processing.

Furthermore , in order to achieve the above-described object, the present invention provides a cylinder structure in which a plating film is formed on an inner surface of an aluminum alloy cylinder bore, and a plating film on a first portion corresponding to the piston vertical dead center equivalent portion of the inner surface of the cylinder bore. Is harder than the plating film of the second part other than the first part of the inner surface of the cylinder bore, and the surface roughness of the plating film of the first part is the surface of the plating film of the second part A cylinder structure characterized by being smaller than roughness is provided.

In the present invention, the first part corresponding to the upper and lower dead center equivalent part of the piston bore on the inner surface of the cylinder bore made of aluminum alloy is heat-treated in a limited manner, and further, the plating film on the inner surface of the cylinder bore is subjected to honing grinding, The surface roughness of the first portion corresponding to the top and bottom dead center on the inner surface of the cylinder bore may be made smaller than the surface roughness of the second portion. Conversely, the plating film may have a Vickers hardness higher than that of the second portion. it can. Thereby, the seizure resistance and wear resistance of the inner surface of the cylinder bore can be improved, good sliding characteristics can be ensured, and an increase in oil consumption and blow-by gas amount can be suppressed.

Further, according to the present invention, the surface roughness of the plating film on the inner surface of the cylinder bore made of an aluminum alloy is made larger at the second part than at the first part, and the lubricating oil is held in the recesses of the second part to lubricate the first part. By securing the oil supply path, low friction, seizure resistance, and wear resistance can be reinforced. Due to the characteristics of the sliding part, the piston part is stabilized by the oil film in the second part, and the plating film Sufficient durability can be obtained without performing the curing process.

  In the present invention, the surface roughness of the first part (piston top and bottom dead center part) is reduced, and in addition to low friction, oil rise and blow-by gas amount can be suppressed. Further, since the plating film of the first part is cured by heat treatment, seizure resistance and wear resistance can be ensured.

  Furthermore, the surface roughness of the second part (other than the top and bottom dead center part of the piston) is made larger than that of the first part, a lubricating oil path (concave part) is formed in the second part, and the low friction and seizure resistance of the first part are formed. Further, the wear resistance can be further improved.

  Moreover, the present invention is a construction method in which sliding characteristics corresponding to the first part and the second part of the inner surface of the cylinder bore are obtained in the piston stroke direction.

The fragmentary sectional view of an internal combustion engine when the piston which reciprocates the cylinder bore inner surface of a cylinder block takes a top dead center position. The fragmentary sectional view of an internal combustion engine when the piston which reciprocates on the cylinder bore inner surface of a cylinder block takes a bottom dead center position state. The perspective view which shows a cylinder bore inner surface (bore surface) in principle. (A) is a plan sectional view showing a piston vertical dead center equivalent part (first part) on the cylinder bore inner surface, and (B) shows an intermediate sliding part (second part) other than the piston vertical dead center equivalent part on the cylinder bore inner surface. FIG. The flowchart which shows embodiment of the processing method of the cylinder bore inner surface which concerns on this invention. Sectional drawing which shows the state which fixed the upper jig of the heat processing apparatus to the cylinder block. The top view which installed the upper jig of the heat processing apparatus on the cylinder block of an internal combustion engine. (A) is a top view which shows the external appearance of the upper jig of a heat processing apparatus, (B) is a side view of the said upper jig. The figure which shows the positional relationship before attaching the top dead center side jig | tool and the bottom dead center jig | tool to a cylinder block. The figure which shows the state which attached the top dead center side jig | tool and the bottom dead center jig | tool to the cylinder block. The figure which shows the relationship between the change of the hardness of a plating film, and the heat processing temperature when the plating film by which the Ni-P (nickel- phosphorus) alloy plating was given to the cylinder bore inner surface was heat-processed (1 hr). The figure which shows the grinding method which performs the honing grinding process with the plating film on the cylinder bore inner surface with the honing grinding jig of the heat treatment apparatus. The figure which shows the cross hatch pattern of the plating film of the cylinder bore inner surface ground with the honing grinding jig. The figure which simplifies in principle the grinding state of the plating film of the cylinder bore inner surface obtained by the grinding process by a honing grinding jig. The figure which shows the construction conditions of the grinding process by a honing grinding jig. The figure which shows the measurement data of the cylinder bore construction surface ground by the honing grinding jig.

  Embodiments according to the present invention will be described below.

  The present invention realizes low friction of the cylinder bore inner surface when constructing the cylinder bore inner surface in the cylinder block of the internal combustion engine, and ensures seizure resistance and wear resistance, while suppressing oil consumption and blow-by gas amount. It is construction technology. This construction technique is applied to a part corresponding to (piston) vertical dead center (hereinafter referred to as a first part) on the inner surface of the cylinder bore with respect to an aluminum alloy cylinder block in which the inner surface of the cylinder bore is plated with Ni-P (nickel-phosphorus) alloy. A machining method and a machining apparatus for an inner surface of a cylinder bore for performing honing grinding after hardening a plating film by performing a required heat treatment.

  The internal combustion engine constitutes the engine 1 as shown in FIGS. 1 and 2, and the engine 1 is configured such that the piston 2 reciprocates on the cylinder bore inner surface 4 of the cylinder block 3. FIG. 1 shows the piston 2 at the top dead center position, and FIG. 2 shows the piston 2 at the bottom dead center position. The cylinder bore inner surface 4 which is the cylinder bore surface of the cylinder block 3 is in the piston stroke direction. Ni-P plating treatment is performed so that sliding characteristics according to stroke characteristics can be obtained, and oil lubrication is used to ensure the lubricity of the piston 2. Reference numeral 5 denotes a connecting rod, reference numeral 6 denotes a crank pin, reference numeral 7 denotes a crankshaft, and reference numeral 8 denotes a combustion chamber above the piston 2.

  In order to improve the seizure resistance and the wear resistance of the first portion 4a, 4c corresponding to the top and bottom dead center where the oil lubrication of the cylinder bore inner surface 4 becomes severe during actual operation, the engine 1 is subjected to temperature control on the plated film. Heat treatment is performed. The first part 4 a or 4 c of the cylinder bore inner surface 4 is a top dead center equivalent part (region) 4 a and a bottom dead center equivalent part (region) 4 c of the piston 2. By heat-treating the first portions 4a and 4c of the cylinder bore inner surface 4, the plating film of the first portions 4a and 4c can improve the hardness, improve the seizure resistance and wear resistance, and improve the sliding resistance. The deformation resistance to be reduced can be suppressed.

  Further, in the second portion 4b, which is an intermediate sliding region other than the first portions 4a and 4c of the cylinder bore inner surface 4, oil lubrication during actual operation of the engine 1 is less severe than the first portions 4a and 4c. The second portion 4b is a (piston) intermediate sliding portion (region) between the first portions 4a and 4c of the cylinder bore inner surface 4.

  When starting the engine (cold), etc., the oil tends to be deficient, so it is necessary to form an appropriate oil pit (oil sump) in the second portion 4b. In the second portion 4b, heat treatment is not actively performed, and an appropriate surface roughness is formed during honing grinding processing to be described later, thereby ensuring lubrication characteristics (oil retention).

  By the way, as shown in FIG. 3, the construction technique of the cylinder bore inner surface 4 is a heat treatment that heats the first portions 4a and 4c of the cylinder bore inner surface 4 made of aluminum alloy to cure the plating film 9 on the cylinder bore inner surface 4. Then, honing grinding is performed, and the first portions 4a and 4c of the cylinder bore inner surface 4 are made to have a plating film 9 as shown in FIG. The surface roughness (uneven shape) 9a can be reduced. This is a construction technique that secures seizure resistance and wear resistance of the first portions 4a and 4c, stabilizes the piston behavior, realizes low friction, and reduces oil consumption and blow-by gas amount.

  On the other hand, as shown in FIG. 4B, the second portion 4b other than the first portions 4a and 4c of the cylinder bore inner surface 4 has a surface roughness 9b of the plated film 9 after honing grinding in the first portions 4a and 4c. Grinding is performed to make it larger. Specifically, the second part 4b of the inner surface 4 of the cylinder bore made of aluminum alloy is subjected to heat shielding control and cooling control from the first parts 4a and 4c so as not to be affected by the heat of the first parts 4a and 4c. In the same honing grinding process, the surface roughness 9b of the plating film 9 in the second part 4b is made larger than the plating film 9 in the first parts 4a and 4c.

The second part 4b of the cylinder bore inner surface 4 is a sliding intermediate part other than the first parts 4a and 4c, and the second part 4b is ground while maintaining heat shielding control and cooling control from the first parts 4a and 4c. It is possible to make the surface roughness of the plating film 9 in the second portion 4b larger than that of the first members 4a and 4c after the honing grinding process. The plating film 9 formed on the cylinder bore inner surface 4 has different surface roughness between the first portions 4a and 4c and the second member 4b. The plating film 9 of the first parts 4a and 4c is different between the first parts 4a and 4c and the second part 4b as in the surface roughness 9a and 9b. The plating film 9 (9a) in the first parts 4a and 4c is harder than the plating film 9 (9b) in the second part 4b and has a small surface roughness. The second portion 4b can increase the surface roughness 9b of the plating film 9 and roughen it, thereby supplying lubricating oil and forming a path (recessed portion) to be held. The low friction, seizure resistance, and wear resistance of the one portion 4a, 4c can be enhanced. By making the second portion 4b of the cylinder bore inner surface 4 easy to retain the lubricating oil, it is possible to effectively suppress running out of the lubricating oil in the entire cylinder bore inner surface 4 at the time of idling stop or cold start of the engine. .

  The second portion 4b of the cylinder bore inner surface 4 has a surface roughness 9b larger than that of the first members 4a and 4c, and due to the characteristics of the sliding portions, there is plenty of lubricating oil during operation. The cylinder bore inner surface 4 has a sufficient oil film to stabilize the piston behavior and maintain low friction even when the second portion 4b is applied larger than the surface roughness 9a of the first portions 4a and 4c. be able to. In addition, since the oil consumption and blow-by gas amount can be sufficiently suppressed as judged from the sliding portion of the cylinder bore inner surface 4, the hardening treatment of the plating film 9 can be performed as a measure for ensuring seizure resistance and wear resistance. Even if it does not perform, it has sufficient durability.

  Furthermore, in the present embodiment, a difference in surface roughness is provided in the sliding stroke direction of the cylinder bore inner surface 4, but since there is no difference in surface roughness in the circumferential direction, the behavior of the piston ring is disturbed. The problem of increased frictional resistance does not occur. Further, the heat treatment and honing grinding of the first portions 4a and 4c and the second portion 4b of the cylinder bore inner surface 4 can be performed simultaneously. Since there is no need for special processing conditions or a masking jig, the cylinder bore inner surface 4 can be easily constructed.

[Cylinder bore inner surface processing method]
FIG. 5 is a flowchart showing a construction procedure for carrying out the machining method of the cylinder bore inner surface 4 for the aluminum alloy cylinder block 17 of the internal combustion engine (engine).

  First, when the cylinder block 17 is prepared and the construction process of the cylinder bore inner surface 4 is started, the construction procedure includes the pre-plating process step 11 for the cylinder bore inner face 4 and the plating process step 12 for the cylinder bore inner face 4 in sequence. In the plating process 12, Ni—P alloy plating is performed on the cylinder bore inner surface 4 to form a plating film.

  When the plating pretreatment step 11 is completed, a heat treatment apparatus 15 (see FIG. 6) is attached to heat treat the plating film formed on the cylinder bore inner surface 4. In the mounting step 13 of the heat treatment apparatus 15, the upper jig 16 of the heat treatment apparatus 15 is installed and fixed on the head surface of the aluminum alloy cylinder block 17. At this time, the cylinder block 17 is installed on the base 14.

  After the upper jig 16 of the heat treatment apparatus 15 is fixed, a heat treatment step 20 for the cylinder bore inner surface 4 is performed. In the heat treatment step 20, heat treatment of the cylinder bore inner surface 4 is performed using a top dead center side jig 21 and a bottom dead center side jig 22 provided in the heat treatment apparatus 15. In the heat treatment step 20, the second portion 4b of the cylinder bore inner surface 4 is cooled in advance, and the plating film 9 in the first portions 4a and 4c is heated in a limited manner, so that the heat treatment of the cylinder bore inner surface 4 is performed. By the heat treatment of the cylinder bore inner surface 4, the first portions 4a and 4c near the top dead center (region) and near the bottom dead center (region) are heated and cured by heating the plating film, and the necessary hardness becomes the first portion 4a, Obtained in 4c plating film.

  When the heat treatment step 20 for heat-treating the cylinder bore inner surface 4 is completed, a honing grinding step 23 is subsequently performed. In the honing grinding process 23, the top dead center side jig 21 and the bottom dead center side jig 22 of the heat treatment apparatus 15 are removed. Thereafter, a honing grinding jig 24 is attached, and honing grinding of the cylinder bore inner surface 4 is performed. By this honing grinding, the cylinder bore inner surface dimension (inner diameter) required for the cylinder bore 18 can be obtained. The cylinder bore 18 of the internal combustion engine (engine) 1 can obtain a highly accurate profile (roundness, cylindricity, etc.) of the cylinder bore inner surface 4.

  In this way, the construction procedure for the cylinder bore inner surface 4 is performed in the order of plating pretreatment for the cylinder bore inner surface 4 → plating treatment, after attaching the upper jig 16 for the heat treatment device 15, and then heat treatment for the cylinder bore inner surface 4 → honing grinding. Then, the construction process of the cylinder bore inner surface 4 is completed.

[Plating pretreatment process]
The plating pretreatment step 11 for the inner surface of the cylinder bore is a process necessary for ensuring the adhesion between the bore inner surface 4 of the cylinder block 17 and the plating film 9. In the plating pretreatment step 11, a degreasing process for removing oil from the cylinder bore inner surface 4 and an etching process for improving the activation and adhesion of the cylinder bore inner surface 4 are performed.

  The etching process includes conventionally used chemical etching, electrolytic etching, and the like, and is to form an uneven shape on the inner surface 4 of the cylinder bore as an anchor in order to improve the adhesion of the plating film 9. The cylinder bore inner surface 4 is cleaned by plating pretreatment to improve the adhesion of the plating film 9, and then the plating treatment is performed.

[Plating process]
In the plating process 12, Ni—P alloy plating is applied to the cylinder bore inner surface 4 to form a plating film 9. The Ni-P alloy plating treatment step 12 is a treatment step for ensuring the necessary wear resistance on the sliding surface with the cylinder bore inner surface sliding material (piston, piston ring), and the cylinder bore inner surface of the aluminum cylinder block 17. 4 is a construction in which a plating film 9 is formed and coated.

  For the plating treatment, a wet dipping method or a high-speed plating method is used. In the high-speed plating method, the plating solution is applied only at the cylinder bore inner surface 4 while flowing at a high current density, and a watt bath is typically used as the treatment solution. The composition of the Watt bath is, for example, nickel sulfate 200 to 600 g / L, boric acid 35 to 55 g / L, 50% hypophosphorous acid or 50% phosphorous acid 1 to 5 g / L, and saccharin sodium 1 to 5 g / L. In the case of the cylinder bore inner surface 4 applied to an engine cylinder, silicon carbide (SiC) particles may be added in order to further improve the wear resistance.

Moreover, as an example of specific plating treatment conditions, a plating solution temperature of 40 ° C. to 80 ° C. and a pH of 1 to 5 are used. The current conditions are such that the current density is 5 with the cylinder block 17 as the negative electrode and the electrode as the positive electrode. When energized at 100 A / dm ² for 5 to 50 minutes, the cylinder bore inner surface 4 can be coated with Ni—P alloy plating to form the plating film 9. For example, the plating film 9 has a Vickers hardness of 550 to 700 HV and a film thickness of 20 to 100 μm, and is excellent in wear resistance.

[Heat treatment equipment installation process]
In the plating process 12, a Ni—P alloy plating plating film 9 is formed on the cylinder bore inner surface 4, and then the upper jig 16 of the heat treatment apparatus 15 is installed on the head surface of the cylinder block 17. As shown in FIG. 6, the heat treatment upper jig 16 is installed on the head surface of the cylinder block 17 via a metal gasket 25, and is fastened and fixed with a fastening bolt 26. The metal gasket 25 is made of the same sealing material as that of the cylinder head gasket so as to prevent damage to the head surface of the cylinder block 17 and leakage of cooling water.

[Heat treatment process]
After the upper jig 16 of the heat treatment apparatus 15 is installed in the cylinder block 17, the top dead center side jig 21 and the bottom dead center side jig 22 of the heat treatment jig are shown in the cylinder block 17, as shown in FIGS. Thus, heat treatment of the plating film 9 on the cylinder bore inner surface 4 is performed.

  As shown in FIG. 10, the plating film on the inner surface 4 of the cylinder bore is heated at a predetermined temperature (for example, 150 ° C. to 450 ° C.) by the first portion 4a corresponding to the piston top dead center portion by the heater 40 of the top dead center side jig 21. Temperature) and heat treatment. Further, the first portion 4c corresponding to the piston bottom dead center portion of the cylinder bore inner surface 4 is heated to a predetermined temperature (for example, a temperature of 150 ° C. to 450 ° C.) by the heater 40 of the bottom dead center side jig 22 and is heat-treated. .

  While the first portions 4a and 4c of the cylinder bore inner surface 4 are being heat-treated, the heat from the heaters 40 and 40 is shielded by the heat-resistant rubbers 47 and 47 as heat insulating members in the second portion 4b. At this time, the second portion 4b of the cylinder bore inner surface 4 is supplied through the cooling water pipes 30 and 30, and is controlled to be cooled to less than 150 ° C., preferably 100 ° C. or less, by circulating cooling water. As described above, the plating film 9 on the cylinder bore inner surface 4 has the second part 4b, which is the intermediate sliding region, while the first parts 4a and 4c are subjected to the limited heat treatment. Is done.

  Therefore, in the plating film 9 on the cylinder bore inner surface 4, the first parts 4a and 4c corresponding to the piston top and bottom dead center parts (areas) are heat-treated to promote the hardening of the plating film, while the second part in the intermediate sliding area. Heat shielding / cooling control is performed on 4b, and the hardness of the plating film 9 is maintained as it is.

  When the heat treatment of the plating film on the cylinder bore inner surface 4 is completed using the top dead center side jig 21 and the bottom dead center side jig 22, etc., the heat treatment apparatus 15 is moved to the next honing grinding step 23.

[Honing grinding process]
In the honing grinding process 23, the top dead center side jig 21 and the bottom dead center side jig 22 of the heat treatment apparatus 15 are taken out and retracted, and then the honing grinding jig 24 is attached to the cylinder block 17 and the honing grinding process is performed. Is implemented as the last construction process. The plating surface 9 of the cylinder bore inner surface 4 of the cylinder block 17 is subjected to an uneven surface treatment by honing grinding.

  Honing grinding has two purposes. One (one) is to grind the coated Ni—P alloy plating film surface layer in order to obtain a target cylinder bore inner surface dimension (inner diameter) during actual engine assembly. The other (the other) is to flatten the convex portion with a plateau (trapezoidal shape) with respect to the concave and convex shape of the cylinder bore inner surface 4 which has completed the cylinder bore inner surface dimension (inner diameter). In the honing grinding process, honing grindstones having different roughnesses are used according to each purpose. In the former, in order to grind the coated Ni—P alloy plating film surface layer faster, the construction is performed using a honing grindstone rougher than the latter.

[Cylinder bore inner surface processing equipment]
The processing device for the cylinder bore inner surface 4 heats the plating film 9 formed by Ni-P alloy plating on the cylinder bore inner surface 4 formed on the cylinder block 17 using a heat treatment device 15 and performs grinding.

  The heat treatment apparatus 15 is installed on a cylinder block 17 installed on the base 14 as shown in FIGS. 6 to 8, and the upper jig 16 fixed and the cylinder block 17 as shown in FIGS. 9 and 10. The top dead center side jig 21 having a heater 40 capable of heat-treating the first portion 4a corresponding to the piston upper dead center corresponding portion of the cylinder bore inner surface 4 and the piston lower dead center corresponding portion of the cylinder bore inner surface 4 corresponding to the piston lower dead point corresponding portion. As shown in FIG. 12, a bottom dead center side jig 22 having a heater 40 capable of heat-treating one part 4c and a honing grinding jig 24 for grinding a plating film on the cylinder bore inner surface 4 are formed. The heat treatment apparatus 15 is a heat treatment jig that heats the plating film on the cylinder bore inner surface 4 and performs honing grinding.

[Upper jig for heat treatment equipment]
When the upper jig 16 of the heat treatment apparatus 15 is installed on the head surface of the cylinder block 17 and fastened, the second portion 4 b of the cylinder bore inner surface 4 is cooled between the cylinder block 17 and the upper jig 16 in a limited manner. The water communication route is completed. The cooling water communication path cools the cooling water by exchanging heat from the wall surface of the second part 4b by passing the cooling water from the cooling water pipe 30 through the upper jig cooling water path 27 and reaching the work cooling water path 28. The heat-exchanged cooling water (warm water) is discharged to the outside of the cylinder block 17 through the workpiece cooling water outlet passage 28b, cooled by a heat exchanger (not shown), and again forms a circulation path returning to the cooling water pipe 2g. Yes. The workpiece cooling water passage 28 is formed so as to cover the cylinder bore inner surface 4 near the second portion 4b, and functions as a water jacket when the internal combustion engine 1 is installed.

  After the upper jig 16 of the heat treatment apparatus 15 is installed and fixed to the cylinder block 17, the top dead center is passed through the loading / unloading holes 37 of the plates 16 a to 16 c of the upper jig 16 with the upper jig 16 fixed. The side jig 21 is inserted (see FIG. 9). The upper / lower mounting hole 37 of the upper jig 16 is a circular hole portion communicating with the cylinder bore inner surface 4 of the cylinder block 17, and the diameter of the circular hole is larger than the finishing diameter for honing grinding on the cylinder bore inner surface 4. The top dead center side jig 21 and the honing grinding jig 24 to be used are formed to have a diameter that allows smooth insertion and removal.

  As shown in FIGS. 6 and 8, the upper jig 16 of the heat treatment apparatus 15 is configured, for example, as an installation table having a three-layer laminated structure, and has a rectangular upper surface plate 16a, intermediate plate (spacer) 16b, and lower surface plate from above. 16c are laminated and positioned by a knock pin (not shown). In order to prevent water leakage from the cooling water passage 27, the upper jig 16 of the heat treatment apparatus 15 is installed after the upper surface plate 16a, the intermediate plate 16b, and the lower surface plate 16c are fastened in advance, or each plate 16a, A packing (sealing means) may be sandwiched between 16b and 16c.

  The upper plate 16a of the upper jig 16 has strength as a seating surface for the fastening bolts 26, is formed of a corrosion-resistant material such as SUS material, and the intermediate plate 16b has a small specific gravity to prevent an increase in weight and is excellent in corrosion resistance. Composed of materials. The lower surface plate 16c is made of a resin heat insulating member such as PPS, PEEK, unilate or the like.

  The lower surface plate 16c of the upper jig 16 is integrally provided with a sleeve-like boss portion 29 that protrudes into the work coolant passage 28 of the cylinder block 17 and thermally seals the top dead center side of the cylinder bore inner surface 4. The boss portion 29 is formed corresponding to the position corresponding to the top dead center side first portion 4a and seals the first portion 4a of the cylinder bore (space) 18 so as not to be cooled. Cooling water is guided to the work cooling water passage 28 of the cylinder block 17 from the cooling water pipe 30 through the upper jig side cooling water passage 27.

  The tightening bolt 26 for tightening the upper jig 16 of the heat treatment apparatus 15 on the head surface of the cylinder block 17 is fastened with a tightening torque equivalent to the cylinder head tightening torque for the actual engine. The heat treatment apparatus 15 performs honing grinding of the cylinder bore inner surface 4 in a subsequent process without moving the upper jig 16 on the cylinder head 17 while the upper jig 16 is installed and fixed to the cylinder head 17. For this reason, the cylinder bore inner surface profile such as roundness and cylindricity can be obtained with high accuracy when the actual machine is assembled.

  On the other hand, as shown in FIG. 7, the internal combustion engine 33 is, for example, a three-cylinder engine, and the upper jig 16 of the heat treatment apparatus 15 is installed and installed on the cylinder block 17 when the construction work of the cylinder bore inner surface 4 is performed. . The upper jig 16 is provided with handling handles (handles) 34 on both sides of the cylinder bores (spaces) 18 in the row direction to facilitate handling on the cylinder block 17. As shown in FIGS. 8A and 8B, a plurality of bolt holes 35 for tightening bolts are formed in the upper jig 16, and an upper jig cooling water path 27 is provided between the bolt holes 35. .

[Top dead center side jig and top dead center side jig]
As shown in FIG. 9 with the upper jig 16 of the heat treatment apparatus 15 fixed to the head surface of the cylinder block 17, the top dead center side jig 21 is inserted from above and the bottom dead center side jig 22 is inserted from below. To be installed. In the state shown in FIG. 10, the top dead center side jig 21 and the bottom dead center side jig 22 are subjected to heat treatment for heating the top dead center side 4a and 4c on the bottom dead center side of the cylinder bore inner surface 4. Is done.

When only the first portions 4a and 4c of the cylinder bore inner surface 4 are heat-treated at a certain temperature or higher, for example, at a temperature range of 150 ° C. to 450 ° C. for 1 hour, a Ni ₃ P phase is precipitated in the plating film 9 and the first portions 4a, 4c, The plating film 9 of 4c is heated and cured. The heat treatment is performed utilizing the property (precipitation effect) of hardening the plating film of the first portions 4a and 4c. The heat treatment is limited to only the first parts 4a and 4c on the top dead center side and the bottom dead center side of the cylinder bore inner surface 4 where seizure resistance and wear resistance are required. The first part 4a , 4c, the second portion 4b is cooled by cooling water flowing through the workpiece cooling water passage (water jacket) 28. For this reason, during the heat treatment of the first portions 4a and 4c, the second portion 4b is not actively subjected to the heat treatment, is cooled to 100 ° C. or less, and the hardness of the plating film 9 is hardly changed.

  The heat processing apparatus 15 is implemented using the top dead center side jig | tool 21 and the bottom dead center side jig | tool 22 shown in FIG. 9 and FIG. The heat treatment jig 15 is divided into a top dead center side jig 21 and a bottom dead center side jig 22, and both structures are the same. Therefore, only the top dead center side jig 21 will be described.

  As shown in FIGS. 9 and 10, the top dead center side jig 21 includes a heater 40 in which a high-temperature heating element 39 is embedded in a cylindrical ceramic molded body 38 having a high-temperature insulating property. Each is supported by an upper end plate 41, a lower end plate 42, and a support bolt 43.

  Further, the top dead center side jig 21 includes an air cylinder 45 having an elevating function. The cylinder block 17 is lifted and retracted when the work of the cylinder block 17 is installed or at the end of heat treatment. It descends until the heater 40 comes to the first part (top dead center side) 4a. The air cylinder 45 and the heater 40 are fastened by bolts or the like (not shown) provided between the mounting plate 46 and the upper end plate 41.

  On the other hand, a U-shaped heat-resistant rubber 47 is provided between the lower end plate 42 of the top dead center side jig 21 and the heater 40 so that the heater 40 made of a brittle material is damaged by a buffering action. In addition to preventing, the contact surface of the heat-resistant rubber 47 facing the cylinder bore inner surface 4 is in close contact with the second portion 4b of the cylinder bore inner surface 4 during heat treatment to prevent heat conduction from the first portion (top dead center side) 4a. have.

  In this heat treatment step 20, as shown in FIG. 10, the cooling water is circulated through the cooling water communication path 36 composed of the upper jig cooling water path 27 and the workpiece cooling water path 28, and the second portion 4 b of the cylinder bore inner surface 4. Is cooled in advance. Thereafter, the top dead center side jig 21 and the bottom dead center side jig 22 are air cylinders 45, 45, and both upper end plates 41, 41 are the top surfaces of the top plate 16 a of the upper jig 16 or the cylinder block 17. The air cylinders 45 and 45 are lowered and raised to the height at which the cylinder bore bottom surface 17b comes into contact.

  When the upper end plate 41 of the top dead center side jig 21 is brought into contact with the top surface of the upper surface plate 16a of the upper jig 16, a closed space for heating the first portion (top dead center side) 4a of the cylinder bore inner surface 4 is formed. Although it is formed, in order to eliminate the influence of heat on the upper jig 16 constituting member more efficiently, an intermediate seal material 48 is installed on the top dead center side jig 21 to form a closed space narrower than the closed space. Let Furthermore, when the upper end plate 41 of the top dead center side jig 21 contacts, the bottom dead center side jig 21 and the lower end plate 42 of the bottom dead center side jig 22 also come into contact with each other. The heat-resistant rubbers 47, 47 are inflated and are in close contact with the second portion 4 b of the cylinder bore inner surface 4 facing each other.

  Heat treatment for restrictively heating the first parts (top dead center side) 4a and (bottom dead center side) 4c of the cylinder bore inner surface 4 is performed by the heaters 40, 40 of the top dead center side jig 21 and the bottom dead center side jig 22. Is controlled by heating. The bore inner surface temperatures of the first portions (top dead center side) 4a and (bottom dead center side) 4c of the cylinder bore inner surface 4 are monitored on the head surface 17a and the cylinder bore bottom surface 17b of the cylinder block 17, respectively. After confirming that the first portions 4a and 4c of the cylinder block 17 have been heated to the set temperature, heat treatment is started. After the heat treatment, the top dead center side jig 21 and the bottom dead center side jig 22 are retracted by ascending or descending. Thereafter, the cylinder bore inner surface 4 of the cylinder block 17 is cooled by spraying using normal temperature water or immersion. This cooling process is necessary to accurately process the cylinder bore inner surface 4 by keeping the temperature of the cylinder block 17 constant in the honing grinding process in the subsequent process.

  By performing heat treatment that heats the first portions 4a and 4c of the cylinder bore inner surface 4 with the heat treatment device 15 in a limited manner, the heat treatment temperature is changed for the cylinder block 17 in which the cylinder bore inner surface 4 is plated with Ni-P alloy. FIG. 11 shows the change in plating film hardness when heat treatment was performed for 1 hour. FIG. 11 shows changes in the hardness of the plating film when the heat treatment temperature is performed in increments of 50 ° C. in the temperature range of room temperature (25 ° C.) and 100 ° C. to 500 ° C.

11, the top dead center side 4a and the bottom dead center side 4c of the first portion of the cylinder bore inner surface 4 of the cylinder block 17 are observed to have a hardened plating film due to precipitation hardening of the Ni ₃ P phase. The range in which the increase in the plating film hardness is recognized is a temperature range from 150 ° C. to 450 ° C. from FIG. 11, and it was found that the plating film hardening is particularly remarkable in the temperature range of 200 ° C. to 400 ° C. . Therefore, the preferable heat treatment conditions are a heat treatment temperature range of 150 ° C. to 450 ° C., and more preferably a temperature range of 200 ° C. to 400 ° C.

When the heat treatment temperature is 500 ° C., the hardness of the plating film is lower than the plating film hardness at room temperature due to excessive precipitation of the Ni ₃ P phase. Moreover, in the range of 20 ° C. to less than 150 ° C., the precipitation hardening phase does not appear and the hardness of the plating film does not change. Therefore, the second portion 4b of the cylinder bore inner surface 4 may be kept within a range of less than 150 ° C. during the heat treatment.

  When the heat treatment of the cylinder bore inner surface 4 is completed, the heat treatment apparatus 15 removes the upper dead center side jig 21 from the upper jig 16 and moves it away while leaving the upper jig 16, while retracting it. The tool 22 is taken out from the cylinder block 17 and removed.

[Honing grinding jig]
As shown in FIG. 12, the honing grinding jig 24 is mounted on the upper jig 16 of the cylinder block 17 from above and performs honing grinding. The honing grinding jig 24 includes a jig main body 51 provided on a rotatable main shaft 50 and a plurality of honing grindstones 52 as longitudinal members arranged circumferentially. The honing grinding jig 24 to which the honing grindstone 52 is attached is lowered while rotating the spindle 50 from the head surface 17a side of the cylinder block 17 toward the cylinder bore inner surface 4 together with a grinding liquid (not shown).

  When the honing grindstone 52 reaches the lower end of the cylinder bore of the first portion (bottom dead center side) 4c of the cylinder bore inner surface 4, the rotation direction of the honing grindstone 52 is reversed and the first portion (top dead center side) 4a of the cylinder bore inner surface 4 is reached. Ascend towards the top of the. The honing grindstone 52 descends as indicated by the arrow A while rotating spirally when descending, and rises as indicated by the arrow B spirally with different rotation directions when ascending.

  In the honing grinding jig 24, the reciprocating rotational motion C while turning is one stroke of the honing grinding process. In the roughing and thinning, the honing grinding jig 24 is increased in accordance with an increase in the number of strokes. The honing grindstone 52 expands by a certain amount toward the outer periphery, finishes the cylinder bore inner surface dimension (inner diameter), and the cross hatch pattern in which the uneven shape of the grinding traces intersects obliquely at the end of the thinning process (see FIG. 13). ) Is applied to the cylinder bore inner surface 4.

  On the other hand, in the finishing, the honing grindstone 52 of the honing grinding jig 24 performs reciprocating rotational movement C while pressing the cylinder bore inner surface 4 whose dimensions are finished by a certain amount, so that the uneven protrusion formed in the honing grinding process 23 is performed. The part is plateaued (trapezoidal shape), and the concave part for retaining the lubricating oil is maintained as it is.

  In the honing grinding process 23, the first portion (top dead center side) 4 a and (bottom dead center side) 4 c in which the hardness of the plating film on the cylinder bore inner surface 4 is cured and the hardness of the plating film are not cured. The second part (intermediate sliding part) 4b is simultaneously subjected to honing grinding.

  At that time, in the honing grinding process 23, honing grinding is performed in the order of so-called roughing, thinning, and finishing. For example, diamond wheel # 200 is used for roughing, and diamond wheel # 400 is used for intermediate drawing. On the other hand, in the latter finishing, a finer grindstone is used to flatten the convex portion of the cylinder bore inner surface 4 (trapezoidal shape) to stabilize the behavior of the piston and piston ring during actual operation. In the honing grinding process, the latter process is commonly called finishing or plateau processing, and a fine grindstone such as diamond grindstone # 1000 is used.

  In the honing grinding process, the first part 4a, 4c of the inner surface 4 of the cylinder bore 4 is more resistant to the grinding depth by the plating film hardening through all of roughing, thinning, and finishing. Therefore, the first part 4a, 4c is increased. The surface roughness can be reduced as compared with the second portion 4b.

[Effect of the embodiment]
In the present embodiment, the first portions 4 a and 4 c of the plating film 9 on the cylinder bore inner surface 4 are heat-cured by limited heat treatment by the heaters 40 of the top dead center side jig 21 and the bottom dead center side jig 22. Is done. In addition, honing grinding is performed by the honing grinding jig 24. In the grinding process, the first portions 4a and 4c have a grinding resistance that is increased by the amount of plating film cured by the heat treatment, and conversely, the surface roughness (roughness) can be reduced. As a result, the plating film 9 on the cylinder bore inner surface 4 has the sliding characteristics necessary for the first parts 4a and 4c, and satisfies low friction, seizure resistance and wear resistance, oil consumption, and suppression of blow-by gas amount. A cylinder bore inner surface 4 is obtained.

  Further, the plating film of the second part 4b of the intermediate sliding part other than the first parts 4a and 4c of the cylinder bore inner surface 4 is hardened by the heat shielding from the heaters 40 and 40 and the cooling control process by the cooling water. It can be kept unchanged. When the plating film 9 on the cylinder bore inner surface 4 is ground by the honing grinding jig 24, the surface roughness of the plating film 9 may be larger than that of the first parts 4a and 4c due to the difference in film hardness. it can. Thereby, a sliding characteristic required for the cylinder bore inner surface 4 of the 2nd site | part 4b can be maintained. The plating film 9 in the second part 4b can form a recess where the lubricating oil stays and maintain the lubricating oil film.

  Further, the plating film 9 on the cylinder bore inner surface 4 is made of different film hardness, and the cylinder block 17 corresponding to the sliding characteristics of the first part 4a, 4c and the second part 4b corresponding to the sliding stroke part is produced. Can do.

On the other hand, in the present embodiment, the cylinder bore inner surface 4 on which the Ni-P alloy plating film is formed is treated with the first parts 4a and 4c by the top dead center side jig 21 and the bottom dead center side jig 22 of the heat treatment jig. In this case, a new phase of Ni ₃ P precipitates from the plating film 9 and is cured by heating. However, when the heat treatment temperature exceeds 450 ° C., Ni ₃ P is excessively precipitated and is less preferable than the hardness of the plating film 9 at room temperature. Further, if the temperature is less than 150 ° C., no change occurs in the hardness of the plating film 9, so that the plating film 9 in the second part 4 b has the first part so that the treatment temperature is less than 150 ° C. Heat is shielded from the heating temperatures of 4a and 4c and cooled with cooling water.

  In addition, the processing device for the cylinder bore inner surface 4 heats the first portions 4a and 4c of the cylinder bore inner surface 4 with a heat treatment device 15 in a temperature range of 150 ° C. to 450 ° C., and the second portion 4b of the cylinder bore inner surface 4 is 150 ° C. The plating film 9 on the cylinder bore inner surface 4 can produce different workpieces for each part by performing the cooling control process at less than 100 ° C., more preferably 100 ° C. or less. The plating film on the cylinder bore inner surface 4 is subjected to honing grinding after producing workpieces having different film hardnesses, so that the plating film 9 on the cylinder bore inner surface 4 inevitably has the first portions 4a, 4c and second of the cylinder bore inner surface 4. A work (cylinder block 17) having surface roughness 9a, 9b corresponding to the sliding characteristics can be produced for each part 4b.

  The honing grinding jig 24 does not use various grinding jigs by setting special honing grinding conditions. The honing grinding jig 24 can use the same honing grinding jig 24 to perform workpieces having different surface roughness for each required part of the inner surface of the cylinder bore. It can be produced at the same time.

[Example]
Next, a specific embodiment of the machining apparatus for the inner surface of the cylinder bore will be described.

  A specific example of a construction technique for performing Ni-P alloy plating on the inner surface of a cylinder bore for a cylinder block made of aluminum die cast mounted on an internal combustion engine will be described.

[Plating pretreatment process]
First, degreasing treatment of the cylinder bore inner surface of the cylinder block 17 was performed on the aluminum die cast cylinder block 17 as a plating pretreatment step 11. The degreasing treatment is performed by immersing the cylinder block 17 in an aqueous solution in which a neutral degreasing agent Mac Screen NG-30 manufactured by Kizai Co., Ltd. is adjusted to a concentration of 40 g / L and a liquid temperature of 50 ° C. The oil was removed. Thereafter, an electrolytic etching process was performed, in which an electrolytic treatment was performed by flowing an etching solution only on the cylinder bore inner surface 4 through a water washing step. Impurities and oxides adhering to the cylinder bore inner surface 4 were removed by electrolytic etching, and an uneven shape (anchor) was formed to ensure adhesion with the plating film. Electrolytic etching treatment uses phosphoric acid 100 to 500 g / L as a treatment liquid, liquid temperature 50 ° C. to 100 ° C., liquid flow rate 10 to 50 cm / sec, electrolysis conditions 10 to 80 A / dm ² , treatment time 0.5 to 5 minutes.

[Plating process]
After the plating pretreatment step, the plating treatment was performed on the inner surface 4 of the cylinder bore that had been pretreated, with a water washing step in between. The plating method used was a high-speed plating method in which the plating solution was applied only to the cylinder bore inner surface 4 while being applied at a high current density.

  In addition, a plating film having a thickness of about 100 μm was formed on the inner surface 4 of the cylinder bore by Ni—P alloy plating treatment within the above-described plating treatment condition range.

[Heat treatment equipment installation process]
After completing the plating process, the upper jig 16 of the heat treatment apparatus 15 was installed and fastened to the head surface of the cylinder block 17 with the water washing process interposed therebetween. The tightening torque of the tightening bolts 26 that fasten the upper jig 16 and the cylinder block 17 was tightened at 40 to 60 N · m, which is equivalent to the cylinder head tightening of the actual engine.

[Heat treatment process]
Next, heat treatment was performed on the cylinder bore inner surface 4 of the plated cylinder block 17. In this heat treatment, the top dead center side jig 21 and the bottom dead center side jig 22 of the heat treatment jig are set on the cylinder bore inner surface 4 of the cylinder block 17, and the first portion (top dead center side) 4a, (Bottom dead center side) Heater 40 and 40 are controlled so that the temperature of 4c is 300 ° C., and the cooling water communication path 36 (27, 28) so that the temperature of the second portion 4b is less than 100 ° C. Cooling water was circulated to control the cooling. The heat treatment time is set to 1 hour, and a plated film that is hardened by about 200 points or more in Vickers hardness than the second portion 4b can be obtained in the first portions 4a and 4c of the cylinder bore inner surface 4.

[Honing grinding process]
As the final construction, honing grinding was performed. In the honing grinding process, the grindstone corresponding to the process (roughing / thinning / finishing (plateau process)) and the construction conditions of the honing grinding process were properly used as shown in FIG. As for the honing grinding jig 24, six honing grindstone jigs 24 corresponding to each of the roughing, thinning, and finishing processes were attached on the circumference. When the size (inner diameter) of the cylinder bore inner surface 4 was obtained by roughing and thinning, the grinding amount of the plating film surface layer was set to 50 μm, and half of the plating film thickness of 100 μm coated in the plating process was left. Furthermore, at the end of the thinning process, the uneven shape of the grinding mark formed a cross-hatch pattern intersecting in an oblique direction on the cylinder bore inner surface 4 and smoothed by finishing (plateau processing) by scraping off the tip of the convex portion. .

[Evaluation of construction surface inside cylinder bore]
The measurement data of the construction surface of the cylinder bore inner surface constructed in this example will be described with reference to FIG.

Surface roughness measurement and plating film hardness measurement of the first part (piston top dead center equivalent part) 4a and the second part (intermediate sliding part) 4b on the same cylinder bore construction surface were performed. In the surface roughness measurement, R _zjis (ten-point average roughness) as an index indicating the degree of unevenness of the entire cylinder bore inner surface 4 and R _vk (JIS B0671 “plateau structure surface on the surface of the concave portion) Evaluation was made using the “Lubricity Evaluation Parameters”. In plating film hardness measurement, both were compared using the Vickers hardness value.

  Measurement was performed using a stylus type surface roughness meter SJ-301 manufactured by Mitutoyo Corporation as a surface roughness measuring machine. In addition, a Vickers hardness tester MVK-H1 manufactured by Mitutoyo Co., Ltd. was used as the plating film hardness measurement machine, and measurement was performed from the plating film cross section by the fracture method at a load of 100 gf and a load holding time of 10 sec. .

  As a result, the cylinder bore inner surface 4 having different surface roughness and hardness at the sliding portion could be manufactured with the same cylinder.

The degree of unevenness R _zjis 1.12 [μm] and the lubricating oil reservoir depth R _vk 0.25 [μm] of the entire cylinder bore inner surface 4 of the first portion 4a are the second portion 4b (R _zjis 1.81 [μm], R _vk 0.40 [μm]). The first portion 4a of the cylinder bore inner surface 4 forms a smooth cylinder bore inner surface 4 effective for suppressing an increase in oil consumption and blow-by gas amount. The smoothing of the first part 4a contributes to the stabilization of the behavior of the piston and the piston ring and realizes low friction because of the sliding characteristics of the first part 4a where oil film lubrication cannot be expected.

  On the other hand, there is a concern that seizure and abnormal wear may occur due to less lubricant remaining in the recess of the first part 4a of the cylinder bore inner surface 4, but in order to prevent seizure and abnormal wear, the first part 4a It was possible to cure the plating film of 200 points or more (first part: 805 HV, second part: 597 HV) as compared with the second part 4 b of the non-heat treated part.

In contrast, the cylinder bore inner surface of the second portion 4b of the cylinder bore inner surface 4 was constructed so that the surface roughnesses R _{zjis and} R _vk were intentionally larger than the first portion 4a, and the effect was actually confirmed. The construction purpose is to form a lubricating oil supply path from the larger recess (oil reservoir) formed in the second part 4b to the first part 4a where the lubricating oil is likely to be deficient during operation, thereby further reducing friction and seizure resistance. And wear resistance can be enhanced. Since the second part 4b has a lot of lubricating oil during actual operation due to the characteristics of the sliding part, the surface roughness is set larger than that of the first part 4a, and the oil film is interposed to stabilize the piston behavior. To maintain low friction.

  Furthermore, the second part 4b of the cylinder bore inner surface 4 can be determined from the sliding part / sliding characteristic, and the oil consumption and blow-by gas amount can be suppressed. As a measure for ensuring seizure resistance and wear resistance, It has been found that the plating film has sufficient durability even if it is not cured.

[Modification]
In the embodiment of the present invention, the example in which the Ni—P alloy plating treatment is performed on the plating treatment liquid used in the plating treatment step has been described. However, insoluble particles such as silicon carbide SiC are mixed into the Ni—P alloy plating treatment to obtain Ni. -P-SiC alloy plating can also be applied. Silicon carbide (SiC) particles can also be added to the plating solution for the purpose of improving wear resistance in the plating treatment for engine cylinders and the like.

  In addition, hard cylinders such as DLC (Diamond-Like Carbon), Ni-SiC (nickel, silicon carbide), and CrN (chromium nitride) are highly plated on the cylinder bore and piston surfaces. A film may be formed.

  The upper jig 16 of the heat treatment apparatus 15 can also be used as a dummy head for installing the honing grinding jig 24. At that time, honing grinding is performed with the bolt tightening axial force of the upper jig 16 and the tightening bolt 26 of the cylinder block 17 being equal to that at the time of engine assembly, so that the circular shape of the cylinder bore inner surface 4 at the time of actual engine assembly is The accuracy of degree and cylindricity can be improved, and further low friction can be realized.

1 Internal combustion engine
2 Piston 3 Cylinder block 4 Cylinder bore inner surface 5 Connecting rod 6 Crank pin 7 Crank shaft
8 Combustion chamber 9 Plating film 11 Pre-plating process 12 Plating process 13 Heat treatment apparatus mounting process 14 Base 15 Heat treatment apparatus (heat treatment jig)
16 Upper jig (installation stand)
17 Cylinder block 18 Cylinder bore 20 Heat treatment process 21 Top dead center side jig 22 Bottom dead center side jig 23 Honing grinding process 24 Honing grinding jig 25 Metal gasket 26 Clamping bolt 27 Cooling water path 28 of the upper jig Cooling water passage 29 Boss part 30 Cooling water piping 34 Handling handle (handle)
35 Bolt hole 36 Cooling water communication path 37 Upper jig access hole 38 Ceramic molded body 39 High temperature heating element 40 Heater 41 Upper end plate 42 Lower end plate 43 Support bolt 45 Air cylinder 46 Mounting plate 47 Heat resistant rubber 50 Main shaft 51 Jig Body 52 Honing wheel

Claims (6)

In the machining method of the inner surface of the cylinder bore in which a plating film is formed on the inner surface of the cylinder bore made of aluminum alloy,
A heat treatment step for heat-treating the first part corresponding to the piston upper and lower dead center equivalent part on the inner surface of the cylinder bore;
And a honing grinding step of grinding a plating film on the inner surface of the cylinder bore cured by the heat treatment. In the machining method of the inner surface of the cylinder bore in which a plating film is formed on the inner surface of the cylinder bore made of aluminum alloy,
A heat treatment step of heat-treating a first portion corresponding to a piston upper dead center equivalent portion of the inner surface of the cylinder bore;
While heat-treating the first part of the inner surface of the cylinder bore, the process of controlling the cooling by limiting heat to the second part other than the first part of the inner surface of the cylinder bore ; and
And a honing grinding step of grinding a plating film on the inner surface of the cylinder bore cured by the heat treatment . The method for processing an inner surface of a cylinder bore according to claim 2 , wherein in the heat treatment step, the heat treatment of the first portion of the inner surface of the cylinder bore and the heat shielding / cooling control processing of the second portion are simultaneously performed. In the heat treatment step, the heat treatment temperature of the first portion on the inner surface of the cylinder bore is heat-treated within a temperature range of 150 ° C. to 450 ° C., and the temperature of the second portion is shielded to a temperature of less than 150 ° C. The method for machining an inner surface of a cylinder bore according to claim 2 or 3, wherein: In the cylinder structure with a plating film formed on the inner surface of the cylinder bore made of aluminum alloy,
The hardness of the plating film of the first part corresponding to the piston upper and lower dead center equivalent part of the inner surface of the cylinder bore is greater than the hardness of the plating film of the second part other than the first part of the inner surface of the cylinder bore, and the first A structure of a cylinder, wherein the surface roughness of the plating film at the site is smaller than the surface roughness of the plating film at the second site. In the plating film on the inner surface of the cylinder bore, the degree of unevenness and the lubricating oil pool depth of the entire cylinder bore inner surface of the first part are smaller than the degree of unevenness and the lubricating oil pool depth of the second part, and the hardness of the plating film The cylinder structure according to claim 5, wherein the first part is larger in Vickers hardness by 200 Hv or more than the second part.