WO2004081252A1 - Nitrided valve lifter and method for manufacture thereof - Google Patents

Nitrided valve lifter and method for manufacture thereof Download PDF

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Publication number
WO2004081252A1
WO2004081252A1 PCT/JP2004/003022 JP2004003022W WO2004081252A1 WO 2004081252 A1 WO2004081252 A1 WO 2004081252A1 JP 2004003022 W JP2004003022 W JP 2004003022W WO 2004081252 A1 WO2004081252 A1 WO 2004081252A1
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WO
WIPO (PCT)
Prior art keywords
valve lifter
compound layer
nitriding
surface roughness
valve
Prior art date
Application number
PCT/JP2004/003022
Other languages
French (fr)
Japanese (ja)
Inventor
Katsuhiro Yamashita
Yasushi Ueno
Kazuyuki Shito
Shinnosuke Munemura
Chikara Sugawara
Original Assignee
Kabushiki Kaisha Riken
Oriental Engineering Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kabushiki Kaisha Riken, Oriental Engineering Co., Ltd. filed Critical Kabushiki Kaisha Riken
Priority to US10/546,902 priority Critical patent/US20060144359A1/en
Priority to CN2004800126733A priority patent/CN1784505B/en
Priority to DE602004010890T priority patent/DE602004010890T2/en
Priority to JP2005503522A priority patent/JP4141473B2/en
Priority to EP04718747A priority patent/EP1602743B1/en
Publication of WO2004081252A1 publication Critical patent/WO2004081252A1/en
Priority to US11/898,446 priority patent/US20080066703A1/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/28—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases more than one element being applied in one step
    • C23C8/30—Carbo-nitriding
    • C23C8/32—Carbo-nitriding of ferrous surfaces
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
    • C23C8/24—Nitriding
    • C23C8/26—Nitriding of ferrous surfaces
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/02—Pretreatment of the material to be coated
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/34—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases more than one element being applied in more than one step
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/12—Transmitting gear between valve drive and valve
    • F01L1/14—Tappets; Push rods
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/12—Transmitting gear between valve drive and valve
    • F01L1/14—Tappets; Push rods
    • F01L1/16—Silencing impact; Reducing wear
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L2303/00—Manufacturing of components used in valve arrangements

Definitions

  • the present invention relates to a valve operating system component of an internal combustion engine, which is a nitrided palbrifter, and a method of manufacturing the same. Furthermore, it relates to a combination of a valve lifter and a cam. Background art
  • a valve lifter 1 that converts the rotation of a cam 11 into a reciprocating motion of a valve 12 is driven by a reciprocating motion with a cylinder block 14.
  • the shim 3 or crown 2 that comes into contact with the cam 11 receives sliding and impact at high surface pressure, resulting in excellent wear and impact resistance.
  • the cam 11 is made of a material having abrasion resistance and impact resistance, and in order to reduce the aggressiveness to the pallet lifter 1 and to prevent boundary lubrication in which the lubrication form is unstable, the surface of the sliding portion is formed. It is necessary to improve the surface roughness.
  • nitriding treatment As a simple means of improving the wear resistance of the valve lifter 1, a nitriding treatment is generally used. However, a compound layer formed on the outermost surface by nitriding (also called a white layer by those skilled in the art) is Because of its high hardness and very brittle properties, it has been conventionally used in a state where it is removed by grinding, polishing, etc., leaving only the nitrided diffusion layer.
  • a process is performed for several hours at a temperature of about 570 ° C. with a target of forming a compound layer of about 10 m.
  • a porous layer is generated, and not only a brittle ⁇ phase (F e 2 to 3 N) is generated, but also the processed product is greatly deformed and the surface roughness is significantly increased. The problem is that it gets worse.
  • the compound layer in the conventional nitriding treatment wherein the outermost layer of porous ⁇ -phase (F e 2 ⁇ 3 N) , as well as dense ⁇ 5 phase thereunder (F e 4 N) and / or ⁇ -phase and ⁇ These are mixed phases, which form relatively coarse columnar crystals oriented almost perpendicular to the surface.
  • the polishing treatment after nitriding is indispensable to reduce the aggressiveness to the mating material. Since the thickness is not uniform, it is necessary to set a relatively large polishing allowance. Furthermore, since uniform polishing is difficult due to variations in hardness and the like, a porous layer may remain after polishing. On the crown surface of a valve lifter that is subject to sliding and impact at high surface pressure, if the porous layer remains after polishing, the porous layer peels off and causes trouble.
  • a polishing means such as a puff is used as a means for removing a porous layer and adjusting the thickness and surface roughness of a compound layer. It consists of ⁇ phase (F e 2 to 3 N) and dense ⁇ ′ phase (F e 4 N) and / or mixed phase of ⁇ phase and ⁇ ′ phase, and the polishing amount depends on the distribution state of each phase and hardness variation. Since it is not uniform, a portion where the compound layer is entirely removed or a portion where the porous layer remains on the same polished surface is likely to be generated, and a uniform compound layer cannot be obtained. For this reason, there is a problem in that the wear resistance varies and the effect of reducing the friction torque cannot be obtained.
  • JP-A-2002-97563 there is a problem in improving the surface roughness even if a uniform compound layer is polished along the surface undulation. Further, there is a problem that the above polishing treatment is very expensive.
  • the cam that slides with the valve lifter is used after polishing the sliding surface, but the surface roughness is relatively rough, the lubrication mode is boundary lubrication, and the crown surface of the valve lifter having a brittle compound layer is used. Increase surface roughness. For this reason, in order to suppress the friction torque from the initial operation and prevent the lubrication form from becoming unstable boundary lubrication, in addition to general polishing, expensive equipment such as one-par lap finishing is required. There is a problem that requires expensive means requiring a long processing time.
  • the present invention solves the above problems by forming a uniform, dense, highly wear-resistant compound layer on the surface at the stage of nitriding treatment, and increasing and treating the surface roughness in the nitriding treatment.
  • An object of the present invention is to provide a valve lifter in which the deformation of the object is small and which does not require polishing treatment for improving abrasion resistance and improving surface roughness and dimensional accuracy, and a method for manufacturing the same.
  • paper on the cam surface An object of the present invention is to provide a valve lifter that can be used in combination with a cam without requiring lapping or the like.
  • a diffusion layer having a relatively low nitrogen concentration and a compound layer having a high nitrogen concentration are formed in layers. If the nitriding temperature is high, the compound layer is formed thick and the outermost surface becomes brittle and porous.Therefore, in order to reduce this as much as possible, the processing temperature may be set to a low value.
  • the diffusion layer also becomes thin. In the valve lifter, since the thickness of the diffusion layer is required to be 50 to 100, a compound having a predetermined hardness and a low surface friction, which has a high hardness and a low friction coefficient, is required to have a thickness of 50 to 100 m. It is desired to obtain a layer.
  • the present inventors have conducted intensive studies and found that the surface roughness of the crown surface of the valve lifter before nitriding was reduced, and the thickness of the compound layer due to nitriding was reduced, so that the surface roughness of the crown surface after nitriding was reduced.
  • the surface roughness of the cam can be reduced by the leveling operation without the need for expensive finishing work such as paper wrap, and overall wear resistance is improved. It has been found that a combination of a valve lifter and a cam that is excellent and has reduced friction torque can be realized, and at the same time, the cost can be reduced.
  • the compound layer formed by nitriding on the outermost surface has a thickness of 1 to 5 m, and the formed compound layer has a surface roughness a 0. 05 or less.
  • the method for manufacturing a valve lifter according to the present invention is characterized in that the surface roughness of the crown surface before nitriding is polished to Ra 0.01 to 0.03. By nitriding the valve lifter polished in this way and selecting a nitriding condition that makes the surface compound layer thickness 1 to 5 nm, high hardness can be achieved.
  • a valve lifter having a nitride compound layer having a low coefficient of friction on the outermost surface of the crown surface and having a surface roughness R a 0.05 or less is obtained.
  • the thickness of the compound layer after nitriding is 1 xm or less, the wear resistance and friction torque reduction effect cannot be obtained. If the thickness is 5 im or more, the formation of a porous layer, an increase in surface roughness, and a thick compound layer are required.
  • the upper limit is set to 5 m because of the problem of peeling of the compound layer during use due to the above.
  • the surface roughness is less than RaO.05, it can be used as a sliding part without any problem.
  • the surface roughness is R a O.05 or more, the aggressiveness of the counterpart material increases, and the effect of reducing the friction torque cannot be obtained. Therefore, in the present invention, the crown surface roughness is set to R a 0.05 or less. I have.
  • the surface roughness is more preferable when the surface roughness is R a O.045 or less, because it has a function of polishing the cam of the mating member and thus has an effect of reducing the friction torque.
  • the porosity of the compound layer after nitriding is 5% or less, and for example, as shown in FIG. Not observed, forming a relatively dense compound layer.
  • the porosity is set to 5% or less in the present invention. If the porosity is more than 5%, the surface roughness is affected, and the wear resistance and friction torque reduction effect cannot be obtained.
  • the surface has a large number of protrusions made of fine carbides, nitrides, sulfides or oxides having an average diameter of 0.5 m or less, or two or more of the above compounds.
  • These protrusions when slid in combination with the cam, improve the cam surface roughness to RaO.02 or less by the polishing function, and disengage without increasing the surface roughness of the valve lift itself. And leave dimples on the surface.
  • the surface roughness of the sliding surface that slides on the cam is 0.2 Rz to 0.7 Rz. However, it is shown that the surface roughness is not improved below 0.2 Rz, and the structure is different.
  • the mating material cam to be combined with the valve lifter according to the present invention is generally used for a camshaft, such as iron, steel, and chill, carburizing, quenching, and the like. It can be used after quenching.
  • a porous layer harmful to the valve lifter is not generated in the nitriding treatment.
  • a nitrogen compound layer containing a uniform and dense equiaxed crystal composed of 1 to 5 ⁇ ′ phase and / or a mixed phase of ⁇ ′ phase and ⁇ phase is formed, and the crown surface is roughened.
  • the value is less than Ra 0.05 and there is almost no deformation. This not only eliminates the need for polishing after nitriding, but also eliminates polishing residue of the porous layer and excessive removal of the necessary nitrogen compound layer caused by polishing when removing the porous layer.
  • the valve lifter is characterized in that the crown surface has a uniform surface hardness of Hv660 or more due to the dense compound layer having a uniform thickness formed by nitriding.
  • a method of manufacturing a valve lifter according to the present invention is characterized in that the valve lifter has a nitriding temperature of 500 to 560. If the nitriding temperature is lower than 500, the nitriding rate is too slow to form a sufficient nitrogen compound layer, and if it exceeds 560 ° C, a porous layer is formed, and the nitrogen layer is removed after the nitriding process. Polishing is required. Further, the present invention is characterized in that an a ′ phase and a mixed phase of a Z or a ′ phase and an ⁇ phase are formed on the crown surface of a valve lift by appropriately adjusting the atmosphere of the nitriding treatment. Further, the nitride compound layer is characterized by including an equiaxed crystal.
  • valve lifter carbon steel for machine structural use, alloy steel, tool steel, and the like generally used for valve lifters can be used as a base material. Wear.
  • nitriding method used for the above-mentioned materials examples include ion nitriding, radical nitriding and salt bath nitriding in addition to gas nitriding and gas soft nitriding. Is extremely low and there is no merit in cost, and the salt bath nitriding method is not preferable because of environmental problems and difficulty in securing surface roughness.In the present invention, gas nitriding and gas soft nitriding are suitable. .
  • the gas nitriding and gas nitrocarburizing treatment generally uses NH 3 , but may use a substance such as urea that forms an atmosphere that exhibits nitriding action on steel. Further, in the present invention are using the N 2 gas, for adjusting the atmosphere, the decomposition gas of the subject 3, reformed gas (RX gas), to supply the required amount of N 2 gas or the like alone or in combination Is also good. While using the co 2 gas as a gas for soft-nitriding in yet present invention, it may also use the gas containing CO, such as reformed gas.
  • the nitrogen compound layer formed on the surface has a T ′ phase and / or a 7 ′′ phase.
  • the effect of the present invention is exhibited if the phase is a mixture of the and ⁇ phases.
  • the nitriding temperature, time, atmosphere, etc. are adjusted by using gas nitriding and gas nitrocarburizing methods, and after the nitriding treatment, there is no porous layer and the porosity is 5% or less.
  • a dense nitride compound layer is formed.
  • a compound layer having a uniform thickness can be obtained without the need for adjusting the thickness of the compound layer after nitriding, adjusting the surface roughness, and polishing for removing the porous layer, thereby securing stable wear resistance. it can.
  • valve lifters There are two types of valve lifters: one is a shim that is installed between the upper surface of the valve body and the cam and the other is a shim that slides on the cam.
  • the valve lifter of the present invention and a method of manufacturing the valve lifter can be applied to both types of valve lifters.
  • the present invention can be applied to a valve lifter provided with an oil hole or a hole for another purpose, a chamfer, a groove, or the like on a crown surface of the valve lifter.
  • the present invention can be applied to the boss portion 4 of the valve lifter that slides the compound layer by the valve lifter and the method of manufacturing the same according to the present invention on the stem end of the valve.
  • FIG. 1 is a cross-sectional view of an example of a valve lifter (shimless) to which the present invention can be applied.
  • FIG. 2 is a sectional view of another example of a valve lifter (with shim) to which the present invention can be applied.
  • FIG. 3 is a micrograph (magnification: 800,000) of a crown cross section after nitriding of a valprift according to the present invention.
  • FIG. 4 is a sectional view clearly showing the compound layer of FIG.
  • FIG. 5 is a micrograph (magnification: 800,000) of a crown cross section after nitriding of a conventional valve lifter.
  • FIG. 6 is a sectional view clearly showing the porous layer of FIG.
  • FIG. 7 is a micrograph (magnification: 800,000) of the crown surface after nitriding of the valve lifter according to the present invention.
  • FIG. 8 is a micrograph (magnification: 800,000) of the crown surface after nitriding of a conventional valve lifter.
  • FIG. 9 is a graph showing the relationship between the cam rotation speed and the friction torque.
  • FIG. 10 is a sectional view showing a usage example of a valve lift.
  • FIG. 11 is a TEM observation photograph (magnification: 30000) of a cross section of the crown face after nitriding of the palbrifter according to the present invention.
  • Fig. 12 is a TEM observation photograph (magnification: 30000) of a crown cross section in which the porous layer has been removed after nitriding of a conventional valve lifter.
  • FIG. 13 is a micrograph ( ⁇ 800) of the crown surface after the sliding test of the valve lifter according to the present invention.
  • FIG. 14 is a diagram showing a change in surface roughness before and after the leveling operation of the valp lifter and the mating material cam according to the present invention and the prior art.
  • FIG. 15 is a diagram showing a change in surface roughness before and after a sliding test between a valve lifter and a mating member cam according to the present invention.
  • the valve lifter 1 of the present invention shown in FIG. 1 and FIG. 2 is provided between a cam 11 and a valve 12 in a direct-acting valve train of an internal combustion engine.
  • This is a sliding part that converts the rotation of 1 into the reciprocating movement of the valve 12.
  • the manufacturing method of the valve lifter 1 of the present invention is used for a sliding surface 2 that slides on a cam (not shown) of the valve lifter 1.
  • the present invention is also applied to the sliding surface 2 of the shim 3 which is in direct sliding contact with the cam as shown in FIG.
  • valve lifter 1 A specific example of the valve lifter 1 according to the present invention will be described below.
  • a material obtained by forging an SCM material is subjected to carburizing, quenching and tempering so that the surface hardness is HRC 58 or more and the effective hardened layer depth is about 1.0 mm.
  • the surface roughness of the moving surface 2 is processed to Ra0.01 to 0.03 using a grinder using a grindstone and an abrasive, but preferably, the surface roughness of the sliding surface 2 is adjusted.
  • the crown surface finish processing is performed so that becomes R a 0.02.
  • gas soft nitriding was performed at a treatment temperature of 520 and a treatment time of 70 minutes so that the surface hardness of the sliding surface 2 was Hv 660 or more and the thickness of the compound layer 6 (see FIG. 4) was 1 to 5 m. I do.
  • the gas used for the gas nitrocarburizing process is a mixed gas of NH 3, N 2 and CO 2 .
  • the compound layer is formed uniformly in the range of 1 to 5 m and the compound layer has no porous layer, so that the deformation is further reduced and the surface roughness is Ra 0.05 or less. Therefore, be careful of temperature uniformity and stirring of atmospheric gas. It is also important to control the composition of the atmosphere gas and the decomposition rate of NH 3 in order to form a compound layer uniformly in the range of 1 to 5 zm and obtain a compound layer without a bolus layer.
  • the pulverizer is nitrided in an atmosphere having a predetermined NH 3 decomposition rate.
  • the decomposition rate of NH 3 can be controlled by the gas exchange rate (flow rate) or the composition ratio of the mixed gas.
  • the nitriding treatment may be performed in another furnace using a gas whose atmosphere is adjusted to a predetermined NH 3 decomposition rate.
  • the decomposition rate of NH 3 in this example was 23%.
  • gas nitrocarburizing is performed under the above-mentioned processing conditions.
  • the processing temperature is 560 ° C and the processing time is 30 minutes, and the processing temperature is 500 ° C and the processing time is 150 minutes, each of them is 3.5 times. m and 2.5 m of a compound layer without a porous layer were obtained.
  • the decomposition rate of NH 3 had to be increased at the treatment temperature of 560 ° C as compared with the 520 ° C treatment, but was the same at 500 ° C.
  • the decomposition rate of NH 3 is controlled in the range of 5 to 50% according to the nitriding temperature of 500 to 560 ° C.
  • valve lifters were arranged in a jig and gas nitrocarburizing treatment was performed so as to uniformly contact the atmosphere gas. As a result, a valve lifter having a uniform compound layer with less deformation was obtained. It should be noted that gas nitrocarburizing at a temperature exceeding 560 In the chemical treatment, the treatment time was short to obtain the required compound layer of 1 to 5 Aim, and it was not possible to adjust the atmosphere to an appropriate one.
  • a diffusion layer 7 on the base material and a porous layer on the surface were formed on the crown surface of the valve lifter by the gas nitrocarburizing treatment in which the temperature, time and atmosphere of the nitriding treatment were controlled.
  • a nitride layer composed of a dense compound layer 6 having a porosity of 5% or less was formed without being formed.
  • fine protrusions composed of fine carbides, nitrides, sulfides or oxides having an average diameter of 0.5 m or less, or two or more of the above compounds are provided. have.
  • the surface roughness at this time is Ra 0.05 or less.
  • the nitrogen compound layer contains equiaxed crystals of 0.5 m or less.
  • Table 1 shows examples of changes in the surface roughness of the sliding surface 2 before and after the nitriding treatment at this time.
  • the surface roughness of the sliding surface before nitriding is polished to Ra 0.012 to 0.028
  • the surface roughness of the sliding surface after nitriding is set to Ra It turns out that it can be made into 0.024-0.045.
  • the surface roughness of the sliding surface before nitriding was Ra If it exceeds 0.03, the surface roughness after nitriding exceeds Ra 0.05.
  • FIG. 5, FIG. 12 and FIG. 8 show the cross section and surface after nitriding of the valve lift of Comparative Example 4 according to the prior art.
  • the valve lift of Comparative Example 4 is gas-nitrogenated at a general temperature of 570 ° C., has a thick compound layer 6 containing columnar crystals, and has a coarse porous layer 8. (See Figure 6).
  • Fig. 12 shows the TEM structure of the cross section of the valve lifter from which the porous layer has been removed by processing, and has relatively coarse columnar crystals oriented almost perpendicularly from the surface.
  • Table 2 shows the change in dimensional accuracy and the thickness of the compound layer and porous layer before and after nitriding of the valve lifters of Example 2 and Comparative Example 4.
  • the deformation shows the maximum displacement after nitriding of the valve lifter crown surface shape before nitriding with reference to the outer periphery.
  • the surface roughness is not increased and the deformation is very small after the nitriding treatment.
  • the porous layer is not formed in the compound layer. This eliminates the need for polishing as a post-process, so that there is no variation in the thickness of the compound layer due to polishing.
  • FIG. 14 shows changes in the surface roughness of the crown surface of the valve lifter and the cam (cam nose portion) of the sliding partner before and after the leveling operation of the valve lifter according to the present invention and the prior art.
  • the valve lifter according to the present invention can improve (reduce) the surface roughness on the cam side by its polishing function without causing an increase in its own surface roughness.
  • the surface roughness of the valve lifter itself significantly increases before and after the running-in operation.
  • FIG. 15 shows changes in the surface roughness of the crown surface of the valve lifter and the cam (cam nose portion) of the mating material after the valve lifter according to the present invention before the running-in operation and after the durability evaluation.
  • the surface roughness of the crown surface of the valve lifter according to the present invention hardly changes, while the surface roughness of the cam side of the mating material is improved to Ra of 0.02 m by its polishing function.
  • the root mean square of the surface roughness used for the evaluation of the total sliding of the valve lifter and cam also tends to converge.
  • FIG. 13 shows the sliding surface of the valve lifter of the present invention after durability evaluation.
  • FIG. 9 is a graph showing the relationship between the rotational speed and the friction torque.
  • the valve lifter according to the present invention has almost no change in its own surface roughness before and after the running-in operation and in the durability evaluation, and the surface roughness on the cam side is improved by the polishing function. It is clear that the sliding resistance is superior to that of the above.
  • the valve lifter according to the present invention has a compound layer thickness after nitriding of 1 to 5 m and a crown roughness after nitriding of Ra 0.05 or less. Furthermore, since a porous layer is not formed on the surface of the compound layer, buffing is basically not required. In the valve lifter 1 manufactured in this manner, a high-cost compound layer having a high hardness and a low friction coefficient can be uniformly present on the sliding surface 2 without basically requiring an expensive polishing treatment after the nitriding treatment. Therefore, its abrasion resistance is stable, and it is possible to significantly reduce manufacturing costs while maintaining high performance.
  • the surface roughness of the cam side can be improved by the polishing function without increasing the surface roughness of the val-prifter itself. Also, expensive equipment such as paper wrap finishing and expensive means requiring long processing time are not required.
  • a dense and hard nitride compound layer of 1 to 5 m without a porous layer is formed, the surface roughness hardly increases before and after nitriding, and the strain deformation is extremely small
  • polishing for adjusting the compound layer after the nitriding treatment such as adjusting the surface roughness and removing the porous layer, is not required. This ensures uniform and stable surface properties The improved wear resistance can be secured.
  • the friction torque can be reduced as compared with the valve lifter according to the prior art. Furthermore, since no expensive polishing treatment is required, a low-cost valve lifter can be obtained.
  • the surface roughness of the cam can be improved by the polishing function without increasing the surface roughness of the valve lifter itself, so that the wear resistance and friction torque are improved.
  • the cam side can be reduced in cost.

Abstract

A method for manufacturing a nitrided valve lifter, which comprises subjecting a sliding surface (2) of a valve lifter (1) or a shim (3) to a carbulizing quenching tempering treatment, and then subjecting the resultant surface to a gas soft nitriding treatment so as for the surface to have a compound layer (6) having a thickness of 1 to 5 μm formed thereon and to have a surface hardness of Hv 660 or greater. The nitride layer on the surface is a dense compound layer (6) exhibiting a porosity of 1 % or less.

Description

明細  Statement
窒化パルブリフタおよびその製造方法 抹術分野  Pall nitrided nitride and method for producing the same
本発明は、 内燃機関の動弁系部品であって窒化を施したパルブリフタ 及びその製造方法に関する。 更に、 バルブリフタとカムの組み合わせに 関する。 背景技術  TECHNICAL FIELD The present invention relates to a valve operating system component of an internal combustion engine, which is a nitrided palbrifter, and a method of manufacturing the same. Furthermore, it relates to a combination of a valve lifter and a cam. Background art
図 1 0に示すように、 内燃機関の直打式動弁機構 1 0においてカム 1 1の回転動作をバルブ 1 2の往復運動に変換するバルブリフタ 1は、 シ リンダプロック 1 4との往復運動による摺動に加え、 カム 1 1と当接す るシム 3又は冠面部 2 (図 1参照） が高面圧での摺動および衝撃カを受 けるため、 優れた耐摩耗性及び耐衝撃性が要求されている。 一方、 カム 1 1は、 耐摩耗性及び耐衝撃性を有する材質とし、 パルブリフタ 1への 攻撃性低減のため、 及び潤滑形態が不安定な境界潤滑とならないように するため、 摺動部表面の表面粗さを向上させる必要がある。 バルブリ フタ 1の耐摩耗性向上の簡単な手段として、 窒化処理が一般に用いられ ているが、 窒化によって最外表面部に形成される化合物層 (当業者の聞 では白層とも呼ばれる。）は、高硬度である一方で非常に脆い性質がある ことから、 従来は研削， 研磨等により除去され、 窒化拡散層のみを残す 状態で用いられてきた。  As shown in FIG. 10, in a direct-acting valve train 10 of an internal combustion engine, a valve lifter 1 that converts the rotation of a cam 11 into a reciprocating motion of a valve 12 is driven by a reciprocating motion with a cylinder block 14. In addition to sliding, the shim 3 or crown 2 (see Fig. 1) that comes into contact with the cam 11 receives sliding and impact at high surface pressure, resulting in excellent wear and impact resistance. Is required. On the other hand, the cam 11 is made of a material having abrasion resistance and impact resistance, and in order to reduce the aggressiveness to the pallet lifter 1 and to prevent boundary lubrication in which the lubrication form is unstable, the surface of the sliding portion is formed. It is necessary to improve the surface roughness. As a simple means of improving the wear resistance of the valve lifter 1, a nitriding treatment is generally used. However, a compound layer formed on the outermost surface by nitriding (also called a white layer by those skilled in the art) is Because of its high hardness and very brittle properties, it has been conventionally used in a state where it is removed by grinding, polishing, etc., leaving only the nitrided diffusion layer.
ところが、 近年における内燃機関の高出力化や低燃費化の要求への対 応として、 窒化による化合物層の高硬度且つ低摩擦係数である特性が着 目され、 カム 1 1と摺動するパルブリフタ 1の冠面部 2におけるフリク シヨン低減の手段として、 研磨後も化合物層を残した仕様の摺動部品及 びその製造方法が提案され、 例えば特開 2002— 97 563号公報に 示されている。 However, in response to recent demands for higher output and lower fuel consumption of internal combustion engines, the characteristics of a compound layer formed by nitridation with high hardness and a low coefficient of friction have been noticed. As a means of reducing friction in the crown part 2 of the bearing, sliding parts with specifications that leave the compound layer even after polishing And a method for producing the same have been proposed, for example, as disclosed in JP-A-2002-97563.
しかし、 上記の特開 2002 - 975 63号公報における摺動部品及 びその製造方法においては、 従来の窒化処理方法が用いられており、 窒 化処理時に化合物層が比較的厚く （5〜1 5 ^ηι) 形成され、 表面が脆 い層となる上に、 処理品の変形も大きく、 表面粗さも低下する。 このた めにその後の工程では、 化合物層を残しながら、 なおかつ表面粗さの調 整もおこなう必要を生じ、 薄い化合物層を更に薄く加工する非常に難し く安定しない研磨処理を必要としている。  However, in the sliding parts and the manufacturing method thereof described in JP-A-2002-97563 described above, a conventional nitriding treatment method is used, and the compound layer is relatively thick during the nitriding treatment (5 to 15 ^). ηι) Formed, the surface becomes a brittle layer, and the treated product is greatly deformed and the surface roughness is reduced. For this reason, in the subsequent steps, it is necessary to adjust the surface roughness while leaving the compound layer, and a very difficult and unstable polishing treatment for processing a thin compound layer further thinner is required.
化合物層を形成させるための一般に行われているガス軟窒化等の処理 では、 1 0 m程度の化合物層の形成を目標として、 570 °C前後の温 度で数時間の処理を行っている。 しかし、 このような処理方法では、 ポ —ラス層が発生し、 脆くなつた ε相 (F e2〜3N) を生じるばかりでな く、 処理品の変形も大きくなると共に表面粗さも大幅に悪化するという 問題がある。 また、 前記の従来の窒化処理における化合物層は、 最外層 のポーラスな ε相 （F e2〜3N)、 並びにその下の緻密なァ 5 相 (F e4 N) および/又は ε相とァ ' 相の混合相からなり、 これらは表面にほぼ 垂直に配向した比較的粗大な柱状結晶を形成している。 In general processes such as gas nitrocarburizing for forming a compound layer, a process is performed for several hours at a temperature of about 570 ° C. with a target of forming a compound layer of about 10 m. However, in such a processing method, a porous layer is generated, and not only a brittle ε phase (F e 2 to 3 N) is generated, but also the processed product is greatly deformed and the surface roughness is significantly increased. The problem is that it gets worse. Further, the compound layer in the conventional nitriding treatment wherein the outermost layer of porous ε-phase (F e 2 ~ 3 N) , as well as dense § 5 phase thereunder (F e 4 N) and / or ε-phase and § These are mixed phases, which form relatively coarse columnar crystals oriented almost perpendicular to the surface.
このような窒化処理では、 表面粗さが相手材の摩耗に大きく影響する ことから、 相手材への攻撃性を低減する意味においても窒化後における 研磨処理が不可欠となっているが、 ポーラス層の厚さが不均一であるた め研磨代を比較的多く設定する必要がある。 更に、 硬度バラツキ等によ り均一な研磨が困難であるために、 研磨後にポーラス層が残る可能性も ある。 高面圧での摺動と衝撃を受けるバルブリフタ冠面においては、 研 磨後にポーラス層が残った状態では、 ポーラス層が剥離脱落し、 トラブ ル発生の原因となる。 特開 2002— 97 563号公報において、 ポーラス層除去、 化合物 層厚さおよび表面粗さの調整の手段として、 パフ等の研磨手段を用いる ことが示されているが、 前述のように化合物層は ε相 （F e2〜3N) 並 びに緻密なァ ' 相 （F e4N) および/又は ε相とァ ' 相の混合相から なり、 各相の分布状態や硬度バラツキなどによって研磨量が均一となら ないことから、 同一の研磨面において化合物層が全て除去された部分や ポ一ラス層が残存する部分などが生じやすく、 均一な化合物層が得られ ない。 このため、 耐摩耗性にバラツキや摩擦トルク低減効果が得られな い問題がある。 In such a nitriding treatment, since the surface roughness greatly affects the wear of the mating material, the polishing treatment after nitriding is indispensable to reduce the aggressiveness to the mating material. Since the thickness is not uniform, it is necessary to set a relatively large polishing allowance. Furthermore, since uniform polishing is difficult due to variations in hardness and the like, a porous layer may remain after polishing. On the crown surface of a valve lifter that is subject to sliding and impact at high surface pressure, if the porous layer remains after polishing, the porous layer peels off and causes trouble. Japanese Patent Application Laid-Open No. 2002-97563 discloses that a polishing means such as a puff is used as a means for removing a porous layer and adjusting the thickness and surface roughness of a compound layer. It consists of ε phase (F e 2 to 3 N) and dense α ′ phase (F e 4 N) and / or mixed phase of ε phase and α ′ phase, and the polishing amount depends on the distribution state of each phase and hardness variation. Since it is not uniform, a portion where the compound layer is entirely removed or a portion where the porous layer remains on the same polished surface is likely to be generated, and a uniform compound layer cannot be obtained. For this reason, there is a problem in that the wear resistance varies and the effect of reducing the friction torque cannot be obtained.
また、 特開 2002— 97563号公報に示されるように、 表面のう ねりに沿うように研磨して均一な化合物層としても、 表面粗さの改善に 問題を生ずる。 更に、 上記の研磨処理は非常に高コストとなる問題があ る。  Also, as shown in JP-A-2002-97563, there is a problem in improving the surface roughness even if a uniform compound layer is polished along the surface undulation. Further, there is a problem that the above polishing treatment is very expensive.
一方、 バルブリフタと摺動するカムは、 摺動面に研磨加工を施して用 いられるが表面粗さは比較的粗く、 潤滑形態が境界潤滑となり、 脆い化 合物層を有する前記バルブリフタ冠面の表面粗さを増大させる。 このた め、 運転初期から摩擦トルクを抑制し、 潤滑形態が不安定な境界潤滑と ならないようにするためには、 一般的な研磨加工に加えてぺ一パーラッ プ仕上げ加工などの高価な設備と長い加工時間を要する高コストな手段 を必要とする問題がある。  On the other hand, the cam that slides with the valve lifter is used after polishing the sliding surface, but the surface roughness is relatively rough, the lubrication mode is boundary lubrication, and the crown surface of the valve lifter having a brittle compound layer is used. Increase surface roughness. For this reason, in order to suppress the friction torque from the initial operation and prevent the lubrication form from becoming unstable boundary lubrication, in addition to general polishing, expensive equipment such as one-par lap finishing is required. There is a problem that requires expensive means requiring a long processing time.
発明の開示  Disclosure of the invention
本発明は、 上記の問題点を解決するもので、 窒化処理の段階において 表面部に均一で緻密な耐摩耗性の高い化合物層を形成し、 且つ、 窒化処 理における表面粗さの増大および処理物の変形が小さく、 耐摩耗性向上 や表面粗さと寸法精度改善のための研磨処理を要さないバルブリフタと その製造方法を提供することを目的とする。 更に、 カム表面にペーパー ラップ仕上げなどを必要とせずにカムと組み合わせて用いることができ るバルブリフタを提供することを目的とする。 SUMMARY OF THE INVENTION The present invention solves the above problems by forming a uniform, dense, highly wear-resistant compound layer on the surface at the stage of nitriding treatment, and increasing and treating the surface roughness in the nitriding treatment. An object of the present invention is to provide a valve lifter in which the deformation of the object is small and which does not require polishing treatment for improving abrasion resistance and improving surface roughness and dimensional accuracy, and a method for manufacturing the same. In addition, paper on the cam surface An object of the present invention is to provide a valve lifter that can be used in combination with a cam without requiring lapping or the like.
一般に、 窒化層においては、 窒素濃度の相対的に低い拡散層と、 窒素 濃度の高い化合物層とが層状に形成される。 窒化処理温度が高いと化合 物層が厚く形成され、 最外表面が脆いポーラス状となるので、 これをで きるだけ少なくするためには処理温度を低く設定すればよいが、 その場 合には拡散層も薄くなつてしまう。 バルブリフタにおいては、 拡散層厚 さを 5 0〜 1 0 0 必要とされるため、 5 0〜 1 0 0 mの前記拡散 層と高硬度で低摩擦係数を示す緻密で所定の表面粗さの化合物層を得る ことが望まれている。  Generally, in the nitride layer, a diffusion layer having a relatively low nitrogen concentration and a compound layer having a high nitrogen concentration are formed in layers. If the nitriding temperature is high, the compound layer is formed thick and the outermost surface becomes brittle and porous.Therefore, in order to reduce this as much as possible, the processing temperature may be set to a low value. The diffusion layer also becomes thin. In the valve lifter, since the thickness of the diffusion layer is required to be 50 to 100, a compound having a predetermined hardness and a low surface friction, which has a high hardness and a low friction coefficient, is required to have a thickness of 50 to 100 m. It is desired to obtain a layer.
そこで、 本発明者等は鋭意研究の結果、 窒化前のバルブリフタ冠面の 表面粗さを小さくし、 且つ、 窒化による化合物層の厚さを薄く抑えるこ とによって、 窒化後の冠面の表面粗さも小さく、 耐摩耗性に優れたバル プリフタを得ることができるということを見いだした。 更に、 前記のバ ルブリフタをカムと組み合わせることで、 ペーパーラップなどの高コス トな仕上げ加工を必要とせずに、 ならし運転によりカムの表面粗さを小 さくさせ、 総合的に耐摩耗性に優れ且つ摩擦トルクを低減したバルブリ フタとカムの組合せを実現することができ、 併せて低コスト化も実現で きることを見出した。  Accordingly, the present inventors have conducted intensive studies and found that the surface roughness of the crown surface of the valve lifter before nitriding was reduced, and the thickness of the compound layer due to nitriding was reduced, so that the surface roughness of the crown surface after nitriding was reduced. We have found that it is possible to obtain a val-prifter that is small and has excellent wear resistance. Furthermore, by combining the valve lifter with a cam, the surface roughness of the cam can be reduced by the leveling operation without the need for expensive finishing work such as paper wrap, and overall wear resistance is improved. It has been found that a combination of a valve lifter and a cam that is excellent and has reduced friction torque can be realized, and at the same time, the cost can be reduced.
すなわち、 本発明による少なくとも冠面にガス窒化又はガス軟窒化を 施したバルプリフタは、 最外表面に窒化による化合物層が 1〜 5 m形 成され、形成された該化合物層の表面粗さが R a 0 . 0 5以下であること を特徴とする。 また、 本発明によるバルブリフタの製造方法は、 窒化前 の冠面の表面粗さを R a 0 . 0 1〜0 . 0 3に研磨加工することを特徴 とする。 そのように研磨加工したバルブリフタを窒化処理し、 表面化合 物層厚さが 1〜5 n mとなる窒化条件を選択することにより、 高硬度で 低摩擦係数の窒化化合物層を冠面の最外表面に有し且つ表面粗さ R a 0. 0 5以下になるバルブリフタを得る。 That is, in the valprifter of the present invention in which at least the crown surface has been subjected to gas nitriding or gas nitrocarburizing, the compound layer formed by nitriding on the outermost surface has a thickness of 1 to 5 m, and the formed compound layer has a surface roughness a 0. 05 or less. Further, the method for manufacturing a valve lifter according to the present invention is characterized in that the surface roughness of the crown surface before nitriding is polished to Ra 0.01 to 0.03. By nitriding the valve lifter polished in this way and selecting a nitriding condition that makes the surface compound layer thickness 1 to 5 nm, high hardness can be achieved. A valve lifter having a nitride compound layer having a low coefficient of friction on the outermost surface of the crown surface and having a surface roughness R a 0.05 or less is obtained.
窒化後の化合物層厚さが 1 xm以下では耐摩耗性や摩擦トルク低減効 果が得られず、 5 im以上ではポ一ラス層の形成や表面粗さの増大、 並 びに化合物層が厚いことによる使用時の化合物層剥離の問題が生じるた め上限を 5 mとしている。 また、 一般に、 表面粗さは、 R a O. 0 5 以下であれば摺動部品として問題なく使用することができる。 表面粗さ が R a O. 0 5以上では、 相手材攻撃性が大きくなり、 摩擦トルク低減 効果も得られないことから本発明では冠面の表面粗さは R a 0. 0 5以 下としている。 表面粗さは、 R a O. 045以下において、 相手材カム を磨く機能を有し、 よつて摩擦トルクを低減する効果が得られるためよ り好ましい。  If the thickness of the compound layer after nitriding is 1 xm or less, the wear resistance and friction torque reduction effect cannot be obtained.If the thickness is 5 im or more, the formation of a porous layer, an increase in surface roughness, and a thick compound layer are required. The upper limit is set to 5 m because of the problem of peeling of the compound layer during use due to the above. In general, if the surface roughness is less than RaO.05, it can be used as a sliding part without any problem. When the surface roughness is R a O.05 or more, the aggressiveness of the counterpart material increases, and the effect of reducing the friction torque cannot be obtained. Therefore, in the present invention, the crown surface roughness is set to R a 0.05 or less. I have. The surface roughness is more preferable when the surface roughness is R a O.045 or less, because it has a function of polishing the cam of the mating member and thus has an effect of reducing the friction torque.
また、 本発明によるバルプリフタにおいては、 窒化後の化合物層の空 孔率が 5%以下であり、 例えば図 3に示すように、 S EMによる倍率 8 000倍での観察において表面部にポーラス層は認められず、 比較的緻 密な化合物層を形成している。 一般に、 空孔率が 5 %以下であればバル プリフタのような摺動部品としては十分緻密であるので、 本発明では空 孔率を 5 %以下とする。空孔率が 5 %以上では表面粗さに影響するため、 耐摩耗性や摩擦トルク低減効果が得られない。  In addition, in the valpriftor according to the present invention, the porosity of the compound layer after nitriding is 5% or less, and for example, as shown in FIG. Not observed, forming a relatively dense compound layer. In general, if the porosity is 5% or less, the porosity is sufficiently dense as a sliding component such as a val-prifter. Therefore, the porosity is set to 5% or less in the present invention. If the porosity is more than 5%, the surface roughness is affected, and the wear resistance and friction torque reduction effect cannot be obtained.
更に、図 7に示すように、表面に平均径 0.5 m以下の微細な炭化物， 窒化物, 硫化物或いは酸化物、 又は前記化合物の 2種以上からなる多数 の突起を有していることを特徴とする。 これらの突起は、 カムと組み合 わせて摺動したときに、 その磨き機能によりカムの表面粗さを RaO.0 2以下まで向上させ、 バルブリフ夕自身の表面粗さを増大させることな く離脱して表面にディンプルを残す特徴がある。 尚、 特開平 6— 2 5 1 1にはカムと摺動する摺動面の表面粗さを 0.2 R z乃至 0.7 R zとし た窒化珪素とすることが示されているが、 0 . 2 R z以下では表面粗さの 改善効果が無いことが示され、 構成が異なるものである。 Furthermore, as shown in Fig. 7, the surface has a large number of protrusions made of fine carbides, nitrides, sulfides or oxides having an average diameter of 0.5 m or less, or two or more of the above compounds. And These protrusions, when slid in combination with the cam, improve the cam surface roughness to RaO.02 or less by the polishing function, and disengage without increasing the surface roughness of the valve lift itself. And leave dimples on the surface. In Japanese Patent Application Laid-Open No. 6-251111, the surface roughness of the sliding surface that slides on the cam is 0.2 Rz to 0.7 Rz. However, it is shown that the surface roughness is not improved below 0.2 Rz, and the structure is different.
本発明に係るバルブリフタと組み合わせる相手材カムには、 一般的に カムシャフトに用いられる铸鉄、 铸鋼およびそれらのチル、 浸炭、 焼入 などの処理を施したものや、 鉄系焼結材およびそれに焼入処理などを施 したものを使用することができる。  The mating material cam to be combined with the valve lifter according to the present invention is generally used for a camshaft, such as iron, steel, and chill, carburizing, quenching, and the like. It can be used after quenching.
更に、本発明によるバルブリフタの製造方法では、窒化処理において、 バルブリフタに有害なポーラス層を生じない。 バルブリフタの表面には 1〜5 のァ ' 相及び/又はァ ' 相と ε相の混合相からなる均一で緻 密な等軸結晶を含む窒素化合物層を形成し、 且つ， 冠面の表面粗さは R a 0 . 0 5以下であり変形も殆どない。 このため窒化処理後の研磨を必 要としないばかりでなく、 研磨によってポ一ラス層を取り除く場合に起 こる、 ポ一ラス層の研磨残りや、 必要な窒素化合物層の研磨による取り すぎも無い。 また、 窒化により形成された均一な厚さで緻密な化合物層 により、 前記バルブリフタは冠面の表面硬度が均一に H v 6 6 0以上で あることを特徴とする。  Further, in the valve lifter manufacturing method according to the present invention, a porous layer harmful to the valve lifter is not generated in the nitriding treatment. On the surface of the valve lifter, a nitrogen compound layer containing a uniform and dense equiaxed crystal composed of 1 to 5 α ′ phase and / or a mixed phase of α ′ phase and ε phase is formed, and the crown surface is roughened. The value is less than Ra 0.05 and there is almost no deformation. This not only eliminates the need for polishing after nitriding, but also eliminates polishing residue of the porous layer and excessive removal of the necessary nitrogen compound layer caused by polishing when removing the porous layer. . Further, the valve lifter is characterized in that the crown surface has a uniform surface hardness of Hv660 or more due to the dense compound layer having a uniform thickness formed by nitriding.
前記に加え本発明のバルブリフ夕の製造方法においては、 前記バルブ リフタの窒化処理温度が 5 0 0〜 5 6 0 であることを特徴とする。 窒 化処理温度が 5 0 0 未満では窒化速度が遅く十分な窒素化合物層が形 成されず、 また 5 6 0 °Cを超えるとポ一ラス層が形成されて窒化処理後 に除去のための研磨が必要となる。 更に、 窒化処理の雰囲気を適切に調 節することによりバルブリフ夕冠面にァ' 相及び Z又はァ ' 相と ε相の 混合相を形成することを特徵とする。 そして、 窒化化合物層は等軸結晶 を含んでなることを特徴とする。  In addition to the above, a method of manufacturing a valve lifter according to the present invention is characterized in that the valve lifter has a nitriding temperature of 500 to 560. If the nitriding temperature is lower than 500, the nitriding rate is too slow to form a sufficient nitrogen compound layer, and if it exceeds 560 ° C, a porous layer is formed, and the nitrogen layer is removed after the nitriding process. Polishing is required. Further, the present invention is characterized in that an a ′ phase and a mixed phase of a Z or a ′ phase and an ε phase are formed on the crown surface of a valve lift by appropriately adjusting the atmosphere of the nitriding treatment. Further, the nitride compound layer is characterized by including an equiaxed crystal.
前記のバルブリフタにおいて、 母材としては一般にバルブリフタに用 いられている機械構造用炭素鋼， 合金鋼， 工具鋼などを用いることがで きる。 In the valve lifter described above, carbon steel for machine structural use, alloy steel, tool steel, and the like generally used for valve lifters can be used as a base material. Wear.
また、 上記材料に用いられる窒化処理法には、 ガス窒化， ガス軟窒化 以外にも、 イオン窒化， ラジカル窒化ゃ塩浴窒化などが挙げられるが、 イオン窒化， ラジカル窒化法は 1回の処理量が非常に少なくコスト面で のメリットがないこと、 塩浴窒化法は環境問題と面粗度の確保が困難で あることから好ましくなく、 本発明においてはガス窒化およびガス軟窒 化が適している。  Examples of the nitriding method used for the above-mentioned materials include ion nitriding, radical nitriding and salt bath nitriding in addition to gas nitriding and gas soft nitriding. Is extremely low and there is no merit in cost, and the salt bath nitriding method is not preferable because of environmental problems and difficulty in securing surface roughness.In the present invention, gas nitriding and gas soft nitriding are suitable. .
ガス窒化及びガス軟窒化処理は N H3 を使用する方法が一般的である が、 鋼材に対して窒化作用を示す雰囲気を形成する尿素などの物質を使 用してもかまわない。 また、 本発明では雰囲気の調節用に N2 ガスを使 用しているが、 題3 の分解ガス， 変成ガス ( R Xガス）， N2 ガス等を 単体又は混合して必要量を供給しても良い。 さらに本発明では軟窒化用 のガスとして c o2 ガスを使用しているが、 変成ガス等の C Oを含むガ スを使用する方法でもかまわない。 また窒化処理に属する酸窒化、 浸硫 窒化等の窒素化合物層中に第三の元素を含む場合であっても、 表面に形 成された窒素化合物層が T ' 相及び/又は 7' ' 相と ε相の混合した相で 有れば本発明の効果を示す。 The gas nitriding and gas nitrocarburizing treatment generally uses NH 3 , but may use a substance such as urea that forms an atmosphere that exhibits nitriding action on steel. Further, in the present invention are using the N 2 gas, for adjusting the atmosphere, the decomposition gas of the subject 3, reformed gas (RX gas), to supply the required amount of N 2 gas or the like alone or in combination Is also good. While using the co 2 gas as a gas for soft-nitriding in yet present invention, it may also use the gas containing CO, such as reformed gas. Further, even when the third element is contained in the nitrogen compound layer such as oxynitriding or sulphonitriding belonging to the nitriding treatment, the nitrogen compound layer formed on the surface has a T ′ phase and / or a 7 ″ phase. The effect of the present invention is exhibited if the phase is a mixture of the and ε phases.
本発明の窒化バルブリフタにおいては、 ガス窒化およびガス軟窒化法 を用いて、 窒化処理温度， 時間， 雰囲気等を調整し、 窒化処理後におい てポ一ラス層が無く、 空孔率が 5 %以下の緻密な窒化化合物層を形成す る。 窒化前後を比較し、 表面粗さの増大が殆どなく、 窒化処理による歪 みや変形も極めて小さい。 よって、 窒化後の化合物層厚さの調整， 表面 粗さの調整およびポーラス層除去のための研磨を必要とせずに均一な厚 さの化合物層が得られ、 これにより安定した耐摩耗性を確保できる。 ま た、 高コストな研磨処理を必要としないため、 低コストで高性能なバル プリフタを得ることができる。 更に、 カムと組み合わせて摺動したとき に、 バルブリフ夕自身の表面粗さを増大させることなく、 その磨き機能 によりカムの表面粗さを向上させることができる。 In the nitriding valve lifter of the present invention, the nitriding temperature, time, atmosphere, etc. are adjusted by using gas nitriding and gas nitrocarburizing methods, and after the nitriding treatment, there is no porous layer and the porosity is 5% or less. A dense nitride compound layer is formed. Compared with before and after nitriding, there is almost no increase in surface roughness, and distortion and deformation due to nitriding are extremely small. Therefore, a compound layer having a uniform thickness can be obtained without the need for adjusting the thickness of the compound layer after nitriding, adjusting the surface roughness, and polishing for removing the porous layer, thereby securing stable wear resistance. it can. In addition, since high-cost polishing is not required, a low-cost, high-performance val-prifter can be obtained. Furthermore, when sliding in combination with a cam In addition, the surface roughness of the cam can be improved by the polishing function without increasing the surface roughness of the valve lift itself.
尚、 バルブリフタには、 バルブリフ夕本体上面とカムとの間にシムを 組み付けカムと摺動させるシムを使用した仕様のバルブリフタと、 シム を用いずにバルブリフ夕冠面で直接カムと摺動させるシムレス仕様のバ ルブリフタがあるが、 本発明のバルブリフタおよびその製造方法は両仕 様のバルブリフ夕とも適用が可能である。 また、 バルブリフタの冠面等 に油孔やその他の目的の穴或いは面取， 溝等を設けたバルブリフ夕につ いても適用できる。 更に、 本発明のバルブリフ夕およびその製造方法に よる化合物層をバルブのステムエンド等と摺動するバルブリフタのボス 部 4への適用も可能である。  There are two types of valve lifters: one is a shim that is installed between the upper surface of the valve body and the cam and the other is a shim that slides on the cam. Although there is a valve lifter having specifications, the valve lifter of the present invention and a method of manufacturing the valve lifter can be applied to both types of valve lifters. Also, the present invention can be applied to a valve lifter provided with an oil hole or a hole for another purpose, a chamfer, a groove, or the like on a crown surface of the valve lifter. Further, the present invention can be applied to the boss portion 4 of the valve lifter that slides the compound layer by the valve lifter and the method of manufacturing the same according to the present invention on the stem end of the valve.
図面の簡単な説明  BRIEF DESCRIPTION OF THE FIGURES
図 1は本発明が適用可能なバルブリフタ (シムレス) の一例の断面図 である。  FIG. 1 is a cross-sectional view of an example of a valve lifter (shimless) to which the present invention can be applied.
図 2は本発明が適用可能なバルブリフタ (シム有) の他の例の断面図 である。  FIG. 2 is a sectional view of another example of a valve lifter (with shim) to which the present invention can be applied.
図 3は本発明によるバルプリフタの窒化後の冠面断面の顕微鏡写真 ( 8 0 0 0倍) である。  FIG. 3 is a micrograph (magnification: 800,000) of a crown cross section after nitriding of a valprift according to the present invention.
図 4は図 3の化合物層を明示する断面図である。  FIG. 4 is a sectional view clearly showing the compound layer of FIG.
図 5は従来技術によるバルブリフタの窒化後の冠面断面の顕微鏡写真 ( 8 0 0 0倍) である。  FIG. 5 is a micrograph (magnification: 800,000) of a crown cross section after nitriding of a conventional valve lifter.
図 6は図 5のポーラス層を明示する断面図である。  FIG. 6 is a sectional view clearly showing the porous layer of FIG.
図 7は本発明によるバルブリフタの窒化後の冠面表面の顕微鏡写真 ( 8 0 0 0倍） である。  FIG. 7 is a micrograph (magnification: 800,000) of the crown surface after nitriding of the valve lifter according to the present invention.
図 8は従来技術によるバルブリフタの窒化後の冠面表面の顕微鏡写真 ( 8 0 0 0倍） である。 図 9はカム回転数と摩擦トルクとの関係を示すグラフ図である。 図 1 0はバルブリフ夕の使用例を示す断面図である。 FIG. 8 is a micrograph (magnification: 800,000) of the crown surface after nitriding of a conventional valve lifter. FIG. 9 is a graph showing the relationship between the cam rotation speed and the friction torque. FIG. 10 is a sectional view showing a usage example of a valve lift.
図 1 1は本発明によるパルブリフタの窒化後における冠面断面の T E M観察写真 （3 0 0 0 0倍） である。  FIG. 11 is a TEM observation photograph (magnification: 30000) of a cross section of the crown face after nitriding of the palbrifter according to the present invention.
図 1 2は従来技術によるバルブリフタの窒化後にポ一ラス層を除去し た冠面断面の T E M観察写真 （3 0 0 0 0倍） である。  Fig. 12 is a TEM observation photograph (magnification: 30000) of a crown cross section in which the porous layer has been removed after nitriding of a conventional valve lifter.
図 1 3は本発明によるバルブリフタの摺動試験後における冠面表面の 顕微鏡写真 （8 0 0 0倍） である。  FIG. 13 is a micrograph (× 800) of the crown surface after the sliding test of the valve lifter according to the present invention.
図 1 4は本発明及び従来技術によるバルプリフタと相手材カムのなら し運転前後における表面粗さの変化を示す図である。  FIG. 14 is a diagram showing a change in surface roughness before and after the leveling operation of the valp lifter and the mating material cam according to the present invention and the prior art.
図 1 5は本発明によるバルブリフタと相手材カムとの摺動試験前後で の表面粗さの変化を示す図である。  FIG. 15 is a diagram showing a change in surface roughness before and after a sliding test between a valve lifter and a mating member cam according to the present invention.
発明を実施するための最良の形態 以下、 本発明による実施の形態の一例を説明する。 図 1と図 2に示す 本発明のバルブリフタ 1は、 図 1 0に示すように、 内燃機関の直打式動 弁機構において、 カム 1 1とバルブ 1 2との間に介装されてカム 1 1の 回転動作をバルブ 1 2の往復運動に変換する摺動部品である。 例えば、 図 1に示すように、 バルブリフタ 1のカム (図示せず) と摺接する摺動 面 2に対して、 本発明のバルブリフ夕 1の製造方法が用いられる。 尚、 図 2に示す如き、 カムと直接摺接するシム 3の摺動面 2に対しても本発 明は適用される。  BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an example of an embodiment according to the present invention will be described. As shown in FIG. 10, the valve lifter 1 of the present invention shown in FIG. 1 and FIG. 2 is provided between a cam 11 and a valve 12 in a direct-acting valve train of an internal combustion engine. This is a sliding part that converts the rotation of 1 into the reciprocating movement of the valve 12. For example, as shown in FIG. 1, the manufacturing method of the valve lifter 1 of the present invention is used for a sliding surface 2 that slides on a cam (not shown) of the valve lifter 1. The present invention is also applied to the sliding surface 2 of the shim 3 which is in direct sliding contact with the cam as shown in FIG.
本発明によるバルブリフタ 1の具体的な実施例を以下に示す。 まず、 S C M材を鍛造成形した素材を、 表面硬さが H R C 5 8以上、 有効硬化 層深さが約 1 . 0 mmとなるように浸炭焼入焼戻処理を施し、 その後、 冠 面即ち摺動面 2の表面粗さを砥石と研磨剤を用いる研削盤を使用し、 R a 0 . 0 1〜0 . 0 3に加工するが、 好ましくは、 摺動面 2の表面粗さ が R a 0.02となるように冠面仕上げ加工を行う。 A specific example of the valve lifter 1 according to the present invention will be described below. First, a material obtained by forging an SCM material is subjected to carburizing, quenching and tempering so that the surface hardness is HRC 58 or more and the effective hardened layer depth is about 1.0 mm. The surface roughness of the moving surface 2 is processed to Ra0.01 to 0.03 using a grinder using a grindstone and an abrasive, but preferably, the surface roughness of the sliding surface 2 is adjusted. The crown surface finish processing is performed so that becomes R a 0.02.
次いで、 摺動面 2の表面硬度が Hv 660以上、 化合物層 6 (図 4参 照） の厚さが 1〜 5 mになるように、 処理温度 520 、 処理時間 7 0分でガス軟窒化処理を行う。 ガス軟窒化処理に使用するガスは、 NH 3 と N2 および C02 の混合ガスを使用している。 Next, gas soft nitriding was performed at a treatment temperature of 520 and a treatment time of 70 minutes so that the surface hardness of the sliding surface 2 was Hv 660 or more and the thickness of the compound layer 6 (see FIG. 4) was 1 to 5 m. I do. The gas used for the gas nitrocarburizing process is a mixed gas of NH 3, N 2 and CO 2 .
ガス軟窒化処理では、 1〜5； mの範囲で均一に化合物層を形成し、 なおかつポーラス層の無い化合物層とするために、 さらに変形が少なく 表面粗さが R a 0. 05以下とするために、 温度の均一性と雰囲気ガス の攪拌に注意して処理をおこなう。 また、 雰囲気ガスの組成と NH3の 分解率を管理することも、 1〜 5 z mの範囲で均一に化合物層を形成し、 なおかつボーラス層の無い化合物層を得るために重要である。 パルブリ フタは、 所定の N H 3の分解率となった雰囲気中で窒化処理される。 N H3の分解率は、 ガス交換率 (流量) あるいは混合ガスの構成比等で管 理することができる。 また、 他炉にて所定の NH3の分解率に雰囲気調 整したガスを用いて窒化処理をおこなってもよい。 本実施例における N H3の分解率は 23 %であった。 In the gas nitrocarburizing treatment, the compound layer is formed uniformly in the range of 1 to 5 m and the compound layer has no porous layer, so that the deformation is further reduced and the surface roughness is Ra 0.05 or less. Therefore, be careful of temperature uniformity and stirring of atmospheric gas. It is also important to control the composition of the atmosphere gas and the decomposition rate of NH 3 in order to form a compound layer uniformly in the range of 1 to 5 zm and obtain a compound layer without a bolus layer. The pulverizer is nitrided in an atmosphere having a predetermined NH 3 decomposition rate. The decomposition rate of NH 3 can be controlled by the gas exchange rate (flow rate) or the composition ratio of the mixed gas. Further, the nitriding treatment may be performed in another furnace using a gas whose atmosphere is adjusted to a predetermined NH 3 decomposition rate. The decomposition rate of NH 3 in this example was 23%.
本実施例においては、前記処理条件でガス軟窒化をおこなっているが、 処理温度 560°Cで処理時間 30分、 及び処理温度 500°Cで処理時間 1 50分にても、 それぞれ 3. 5 mと 2. 5 mのポ一ラス層の無い 化合物層が得られた。 なおこのときの NH3の分解率は 520 °C処理と 比較して、 処理温度 560 °Cでは大きくする必要があつたが、 5 00 °C では同じであった。 NH3の分解率は、 窒化処理温度 5 0 0〜5 6 0°C に従って 5〜 50 %の範囲で管理する。 また、 バルブリフタは治具に整 列して並べ、 均一に雰囲気ガスに触れるようにガス軟窒化処理をおこな うことで、より変形の少ない均一な化合物層のバルプリフタが得られた。 なお、 従来おこなわれているような 560 °Cを超える温度のガス軟窒 化処理では、 必要とされる 1〜 5 Aimの化合物層とするには処理時間が 短く、 適切な雰囲気に調節することができなかった。 NH3の分解が表 面で行われた場合のみ窒化に有効に作用することから、 NH3の分解率 の大きい雰囲気中においては処理品表面の NH 3の分解反応は減少し、 ポーラス層の無い化合物層が形成されたが化合物層にパラツキを生じ、 NH3の分解率の小さい雰囲気中においては処理品表面の窒化が活発に 行われ、 化合物層にポ一ラス層を生じた。 In this embodiment, gas nitrocarburizing is performed under the above-mentioned processing conditions. However, even when the processing temperature is 560 ° C and the processing time is 30 minutes, and the processing temperature is 500 ° C and the processing time is 150 minutes, each of them is 3.5 times. m and 2.5 m of a compound layer without a porous layer were obtained. At this time, the decomposition rate of NH 3 had to be increased at the treatment temperature of 560 ° C as compared with the 520 ° C treatment, but was the same at 500 ° C. The decomposition rate of NH 3 is controlled in the range of 5 to 50% according to the nitriding temperature of 500 to 560 ° C. In addition, the valve lifters were arranged in a jig and gas nitrocarburizing treatment was performed so as to uniformly contact the atmosphere gas. As a result, a valve lifter having a uniform compound layer with less deformation was obtained. It should be noted that gas nitrocarburizing at a temperature exceeding 560 In the chemical treatment, the treatment time was short to obtain the required compound layer of 1 to 5 Aim, and it was not possible to adjust the atmosphere to an appropriate one. Since the decomposition of NH 3 acts effectively to nitride only when done in the front surface, in a large ambient decomposition rate of NH 3 is decreased decomposition reaction of NH 3 of treated product surface, no porous layer Although the compound layer was formed, the compound layer was uneven, and in the atmosphere where the decomposition rate of NH 3 was low, the surface of the treated product was actively nitrided, and a porous layer was formed in the compound layer.
窒化処理の温度、 時間と雰囲気が管理された前記ガス軟窒化処理によ つて、 バルブリフタの冠面には、 図 4に示すように母材上に拡散層 7及 び表面にポ一ラス層を形成せず空孔率が 5 %以下の緻密な化合物層 6か らなる窒化層を形成している。  As shown in Fig. 4, a diffusion layer 7 on the base material and a porous layer on the surface were formed on the crown surface of the valve lifter by the gas nitrocarburizing treatment in which the temperature, time and atmosphere of the nitriding treatment were controlled. A nitride layer composed of a dense compound layer 6 having a porosity of 5% or less was formed without being formed.
また、化合物層表面には、 図 7に示す平均径 0.5 m以下の微細な炭 化物， 窒化物， 硫化物或いは酸化物、 又は前記化合物の 2種以上からな る多数の突起 （白い粒状部分） を有している。 このときの表面粗さは R a 0.0 5以下である。 更に、 図 1 1に示すように窒素化合物層に 0.5 m以下の等軸結晶を含んでいる。 このようにして得られた本発明によ るバルプリフタは、 表面粗さと寸法精度改善のための研磨処理を要さな い。  In addition, on the surface of the compound layer, as shown in FIG. 7, fine protrusions (white granular parts) composed of fine carbides, nitrides, sulfides or oxides having an average diameter of 0.5 m or less, or two or more of the above compounds are provided. have. The surface roughness at this time is Ra 0.05 or less. Further, as shown in FIG. 11, the nitrogen compound layer contains equiaxed crystals of 0.5 m or less. The thus obtained valp-lifter according to the present invention does not require polishing treatment for improving surface roughness and dimensional accuracy.
次に、 比較例として、 前記の本発明による実施例と同一の素材を使用 し、 窒化前の冠面の表面粗さを異にするが、 本発明の窒化処理と同一条 件の加工方法によりパルブリフタを作成した。  Next, as a comparative example, the same material as that in the example according to the present invention was used, and the surface roughness of the crown surface before nitriding was different, but by the processing method under the same conditions as the nitriding treatment of the present invention. Pal-brifter was made.
このときの摺動面 2における、 窒化処理前と後での表面粗さの変化の 例を表 1に示す。 本発明の実施例では窒化前の摺動面の表面粗さを R a 0. 0 1 2〜0. 028に研磨加工してあることから、 窒化後の摺動面 の表面粗さを R a 0. 024〜0. 045とさせ得ることがわかる。 こ れに対し比較例 1、 2、 3では、 窒化処理前の摺動面の表面粗さが R a 0 . 0 3を超えた場合、 窒化処理後の表面粗さで R a 0 . 0 5を超えて しまう。 Table 1 shows examples of changes in the surface roughness of the sliding surface 2 before and after the nitriding treatment at this time. In the embodiment of the present invention, since the surface roughness of the sliding surface before nitriding is polished to Ra 0.012 to 0.028, the surface roughness of the sliding surface after nitriding is set to Ra It turns out that it can be made into 0.024-0.045. In contrast, in Comparative Examples 1, 2, and 3, the surface roughness of the sliding surface before nitriding was Ra If it exceeds 0.03, the surface roughness after nitriding exceeds Ra 0.05.
Figure imgf000014_0001
図 5、 図 1 2および図 8は、 従来技術による比較例 4のバルブリフ夕 について窒化後の断面および表面を示したものである。
Figure imgf000014_0001
FIG. 5, FIG. 12 and FIG. 8 show the cross section and surface after nitriding of the valve lift of Comparative Example 4 according to the prior art.
従来技術による比較例 4のバルブリフ夕は、 一般的な 5 7 0 °Cでガス 軟窒化されていて、 柱状晶を含む化合物層 6が厚く形成され、 粗大なポ 一ラス層 8を有している （図 6参照）。 また、 変形が大きく面粗度も悪化 しているので、 後工程のバフ研磨によりボーラス層の除去が必要となつ ている。 図 1 2にポ一ラス層を加工により取り除いたバルブリフタ断面 の T E M組織を示しているが、 表面からほぼ垂直に配向した比較的粗大 な柱状結晶を有している。  The valve lift of Comparative Example 4 according to the prior art is gas-nitrogenated at a general temperature of 570 ° C., has a thick compound layer 6 containing columnar crystals, and has a coarse porous layer 8. (See Figure 6). In addition, since the deformation is large and the surface roughness is deteriorated, it is necessary to remove the bolus layer by buff polishing in a later process. Fig. 12 shows the TEM structure of the cross section of the valve lifter from which the porous layer has been removed by processing, and has relatively coarse columnar crystals oriented almost perpendicularly from the surface.
表 2に、 実施例 2および比較例 4のバルブリフタの窒化前後における 寸法精度の変化および化合物層， ポ一ラス層の厚さを示す。 変形は、 窒 化前のバルブリフタ冠面形状に対し、 外周部を基準として窒化後の最大 変位を示す。 本発明によるバルブリフタは、 窒化処理後において、 表面 粗さの増大がなく変形も非常に少なく、 更に化合物層にポーラス層が形 成されていない。 これにより、 後加工としての研磨を要しないため研磨 による化合物層厚さにパラツキが生じることがない。 表 2 Table 2 shows the change in dimensional accuracy and the thickness of the compound layer and porous layer before and after nitriding of the valve lifters of Example 2 and Comparative Example 4. The deformation shows the maximum displacement after nitriding of the valve lifter crown surface shape before nitriding with reference to the outer periphery. In the valve lifter according to the present invention, the surface roughness is not increased and the deformation is very small after the nitriding treatment. Further, the porous layer is not formed in the compound layer. This eliminates the need for polishing as a post-process, so that there is no variation in the thickness of the compound layer due to polishing. Table 2
Figure imgf000015_0001
Figure imgf000015_0001
[実験例] [Experimental example]
前記した本実施例の本発明によるバルプリフタと比較例 4の従来技術 によるバルブリフタおよびカム部をチル化したチルカムをエンジンに組 付け、 回転数 1 0 0 0〜 4 0 0 O rpm でモーターリング試験を行ない、 摺動時の摩擦トルクを測定した。 図 1 4は、 本発明と従来技術によるパ ルブリフタのならし運転前後でのバルブリフタの冠面及び摺動相手材の カム （カムノーズ部） の表面粗さの変化を示している。 本発明によるバ ルブリフタは 自身の表面粗さの増大を起こすことなく、 その磨き機能 によりカム側の表面粗さを向上 （低減） させることができる。 一方、 従 来技術によるバルブリフタは、 ならし運転前後でバルブリフタ自身の表 面粗さが大幅に増大する。  The valve lifter according to the present invention of the present embodiment described above and the valve lifter according to the prior art of Comparative Example 4 and a chill cam having a chilled cam portion were assembled in an engine, and a motoring test was performed at a rotation speed of 100 to 400 rpm. The friction torque during sliding was measured. FIG. 14 shows changes in the surface roughness of the crown surface of the valve lifter and the cam (cam nose portion) of the sliding partner before and after the leveling operation of the valve lifter according to the present invention and the prior art. The valve lifter according to the present invention can improve (reduce) the surface roughness on the cam side by its polishing function without causing an increase in its own surface roughness. On the other hand, in the valve lifter according to the conventional technology, the surface roughness of the valve lifter itself significantly increases before and after the running-in operation.
また、 図 1 5は、 本発明によるバルブリフタのならし運転前から耐久 評価後のバルブリフタの冠面と相手材のカム （カムノ一ズ部） の表面粗 さの変化を示している。 本発明によるバルブリフタの冠面の表面粗さは 殆ど変化がなく、 一方相手材のカム側の表面粗さをその磨き機能により R aで 0 . 0 2 mまで向上させている。 また、 バルブリフタとカムの総 合摺動評価として用いられている表面粗さの二乗平均からも収束の傾向 である。 図 1 3は耐久評価後の本発明のバルブリフタの摺動表面を示し ている。 摺動前の表面に見られた突起は、 カムと組み合わせて摺動した ときに、 その磨き機能によりカムの表面粗さを R aで 0 . 0 2 m以下ま で向上させ、 バルブリフタ自身の表面粗さを増大させることなく保油効 果を向上させるディンプルを残して離脱している。 FIG. 15 shows changes in the surface roughness of the crown surface of the valve lifter and the cam (cam nose portion) of the mating material after the valve lifter according to the present invention before the running-in operation and after the durability evaluation. The surface roughness of the crown surface of the valve lifter according to the present invention hardly changes, while the surface roughness of the cam side of the mating material is improved to Ra of 0.02 m by its polishing function. The root mean square of the surface roughness used for the evaluation of the total sliding of the valve lifter and cam also tends to converge. FIG. 13 shows the sliding surface of the valve lifter of the present invention after durability evaluation. The protrusion seen on the surface before sliding slid in combination with the cam Occasionally, the polishing function improves the surface roughness of the cam to less than 0.02 m in Ra, leaving the dimple to improve the oil retaining effect without increasing the surface roughness of the valve lifter itself. are doing.
図 9は回転数と摩擦トルクの関係を示したグラフである。 この結果、 本発明によるバルブリフタは、 ならし運転前後及び耐久評価での自己の 表面粗さの変化が殆どなく、 且つ、 磨き機能によりカム側の表面粗さを 向上させ、 摩擦トルクが従来技術によるものより低く、 摺動抵抗におい ても優位であることがわかる。  FIG. 9 is a graph showing the relationship between the rotational speed and the friction torque. As a result, the valve lifter according to the present invention has almost no change in its own surface roughness before and after the running-in operation and in the durability evaluation, and the surface roughness on the cam side is improved by the polishing function. It is clear that the sliding resistance is superior to that of the above.
先に述べたように、 本発明によるバルブリフタは、 窒化後の化合物層 厚さが 1〜5 mであり、且つ、窒化後の冠面の面粗度が R a 0 . 0 5以 下であり、 更に化合物層表面部にポーラス層が形成されないことを特徴 としているため、 基本的にバフ研磨処理を必要としない。 このようにし て製造されるバルブリフタ 1では、 窒化処理後に高コストな研磨処理を 基本的に必要とせず、 摺動面 2に高硬度且つ低摩擦係数な化合物層を均 一に存在させることができるため耐摩耗性も安定しており、 高性能を維 持しつつ製造コストを大幅に低減することが可能である。 更に、 相手材 のカムと組み合わせて摺動させることでバルプリフタ自身の表面粗さの 増大を起こすことなく、 その磨き機能によりカム側の表面粗さを向上さ せることができるため、 相手材のカムについてもペーパーラップ仕上げ 加工などの高価な設備と長い加工時間を要する高コストな手段を必要と しない。  As described above, the valve lifter according to the present invention has a compound layer thickness after nitriding of 1 to 5 m and a crown roughness after nitriding of Ra 0.05 or less. Furthermore, since a porous layer is not formed on the surface of the compound layer, buffing is basically not required. In the valve lifter 1 manufactured in this manner, a high-cost compound layer having a high hardness and a low friction coefficient can be uniformly present on the sliding surface 2 without basically requiring an expensive polishing treatment after the nitriding treatment. Therefore, its abrasion resistance is stable, and it is possible to significantly reduce manufacturing costs while maintaining high performance. Furthermore, by sliding in combination with the cam of the mating material, the surface roughness of the cam side can be improved by the polishing function without increasing the surface roughness of the val-prifter itself. Also, expensive equipment such as paper wrap finishing and expensive means requiring long processing time are not required.
以上のように、 本発明によるバルブリフ夕では、 ポーラス層の無い 1 〜5 mの緻密で硬い窒化化合物層を形成し、 窒化前後で表面粗さの増 大が殆どなく、 更に歪み変形が極めて小さいガス窒化処理をおこなうこ とで、 表面粗さの調整およびポーラス層の除去など、 窒化処理後の化合 物層を調整する研磨を必要としない。 これにより表面性状が均一で安定 した耐摩耗性を確保できる。 As described above, in the valve lift according to the present invention, a dense and hard nitride compound layer of 1 to 5 m without a porous layer is formed, the surface roughness hardly increases before and after nitriding, and the strain deformation is extremely small By performing the gas nitriding treatment, polishing for adjusting the compound layer after the nitriding treatment, such as adjusting the surface roughness and removing the porous layer, is not required. This ensures uniform and stable surface properties The improved wear resistance can be secured.
また、 均一な化合物層が得られることにより、 従来技術によるバルブ リフタに比べて摩擦トルクを低減することができる。 更に高コストな研 磨処理を必要としないため、 低コストなバルブリフタを得ることができ る。  Further, since a uniform compound layer is obtained, the friction torque can be reduced as compared with the valve lifter according to the prior art. Furthermore, since no expensive polishing treatment is required, a low-cost valve lifter can be obtained.
更に、 カムと組み合わせて摺動させることでバルブリフタ自身の表面 粗さの増大を起こすことなく、 その磨き機能によりカム側の表面粗さを 向上させることができるため、 耐摩耗性及び摩擦トルクの向上に加え、 カム側の低コスト化も実現できる。  Furthermore, by sliding in combination with the cam, the surface roughness of the cam can be improved by the polishing function without increasing the surface roughness of the valve lifter itself, so that the wear resistance and friction torque are improved. In addition, the cam side can be reduced in cost.

Claims

請求の範囲 The scope of the claims
1. 内燃機関用パルブリフタの少なくとも冠面にガス窒化又はガス軟 窒化を施したバルブリフタにおいて、 最外表面に窒化による化合物層が 1〜5 zm形成され、形成された該化合物層の表面粗さが R a 0.0 5以 下であることを特徴とするバルブリフタ。  1. In a valve lifter in which at least the crown face of an internal combustion engine palbrifter has been subjected to gas nitriding or gas nitrocarburizing, a compound layer is formed on the outermost surface by nitriding at 1 to 5 zm, and the surface roughness of the formed compound layer is reduced. A valve lifter having a Ra of not more than 0.05.
2. 該化合物層がァ ' 相及び/又はァ ' 相と ε相の混合相からなるこ とを特徴とする請求項 1に記載のバルブリフタ。  2. The valve lifter according to claim 1, wherein the compound layer comprises an α ′ phase and / or a mixed phase of an α ′ phase and an ε phase.
3. 該化合物層が等軸結晶を含んでなることを特徴とする請求項 1又 は 2記載のバルブリフ夕。  3. The valve lift according to claim 1, wherein the compound layer comprises equiaxed crystals.
4. 該化合物層の空孔率が 5 %以下であることを特徴とする請求項 1 乃至 3の何れかに記載のバルブリフタ。 4. The valve lifter according to claim 1, wherein the porosity of the compound layer is 5% or less.
5. 該化合物層の表面に、 平均径 0.5 m以下の多数の突起を有して いることを特徵とする請求項 1乃至 4の何れかに記載のバルブリフタ。 5. The valve lifter according to any one of claims 1 to 4, wherein the surface of the compound layer has a large number of protrusions having an average diameter of 0.5 m or less.
6. 該化合物層の表面の突起が、 窒化物、 或いは炭素、 酸素、 ィォゥ 及びこれらの化合物のうち少なくとも 1種類を含む窒化物であることを 特徴とする、 請求項 1乃至 5の何れかに記載のバルブリフ夕。 6. The protrusion on the surface of the compound layer is a nitride or a nitride containing at least one of carbon, oxygen, zeolite, and these compounds. The described valve riff.
7. バルブリフタ冠面の表面硬度が、 Hv 660以上であることを特 徴とする請求項 1乃至 6の何れかに記載のバルブリフ夕。  7. The valve lift according to claim 1, wherein the crown surface of the valve lifter has a surface hardness of Hv 660 or more.
8. バルブリフタ冠面がカムとの摺動によりカムの表面粗さを向上さ せ、 且つ、 バルブリフタ自身の表面粗さを増大させることのないことを 特徴とする請求項 1乃至 7の何れかに記載のバルブリフタとカムの組み 合わせ。  8. The valve lifter according to any one of claims 1 to 7, wherein the crown surface of the valve lifter improves the surface roughness of the cam by sliding with the cam, and does not increase the surface roughness of the valve lifter itself. Combination of valve lifter and cam described.
9. 内燃機関用バルブリフタの少なくとも冠面にガス窒化又はガス軟 窒化を施すバルブリフタの製造方法において、 窒化前の冠面の表面粗さ を R a 0.0 1〜0. 0 3に研磨加工することを特徴とするバルブリフ夕 の製造方法。 9. In a method of manufacturing a valve lifter in which at least a crown surface of an internal combustion engine valve lifter is subjected to gas nitriding or gas nitrocarburizing, the surface roughness of the crown surface before nitriding is polished to Ra 0.01 to 0.03. A characteristic method of manufacturing valve lifts.
1 0 . 前記バルブリフタの製造方法において、 窒化処理温度が 5 0 0 〜5 6 0 °Cであることを特徴とする請求項 9に記載のバルブリフタの製 造方法。 10. The method of manufacturing a valve lifter according to claim 9, wherein in the method of manufacturing a valve lifter, a nitriding treatment temperature is 500 to 560 ° C.
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006214313A (en) * 2005-02-02 2006-08-17 Riken Corp Valve lifter
JP5898092B2 (en) * 2010-12-13 2016-04-06 川崎重工業株式会社 DRIVE CAM, MANUFACTURING METHOD THEREOF AND ENGINE VALVE DEVICE
JP2016065533A (en) * 2014-09-26 2016-04-28 株式会社リケン Valve lifter and manufacturing method thereof
JP2017186637A (en) * 2015-08-17 2017-10-12 Ntn株式会社 Slide member and production method thereof
US11007572B2 (en) 2015-08-17 2021-05-18 Ntn Corporation Sliding member and method for producing same

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JP4141473B2 (en) 2008-08-27
ES2295833T3 (en) 2008-04-16
US20080066703A1 (en) 2008-03-20
EP1602743B1 (en) 2007-12-26
DE602004010890D1 (en) 2008-02-07
TW200506181A (en) 2005-02-16
CN1784505B (en) 2010-11-03
CN1784505A (en) 2006-06-07
US20060144359A1 (en) 2006-07-06
KR20050118175A (en) 2005-12-15
DE602004010890T2 (en) 2008-12-11
EP1602743A1 (en) 2005-12-07
JPWO2004081252A1 (en) 2006-06-15
EP1602743A4 (en) 2007-01-24

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