WO2013047761A1 - Method for manufacturing camshaft for internal combustion engine - Google Patents

Method for manufacturing camshaft for internal combustion engine Download PDF

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Publication number
WO2013047761A1
WO2013047761A1 PCT/JP2012/075109 JP2012075109W WO2013047761A1 WO 2013047761 A1 WO2013047761 A1 WO 2013047761A1 JP 2012075109 W JP2012075109 W JP 2012075109W WO 2013047761 A1 WO2013047761 A1 WO 2013047761A1
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WO
WIPO (PCT)
Prior art keywords
cooling
camshaft
internal combustion
combustion engine
manufacturing
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PCT/JP2012/075109
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French (fr)
Japanese (ja)
Inventor
隆 舩橋
俊輔 竹口
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日本ピストンリング株式会社
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Application filed by 日本ピストンリング株式会社 filed Critical 日本ピストンリング株式会社
Priority to JP2013536432A priority Critical patent/JP5988985B2/en
Priority to KR1020147007129A priority patent/KR101539314B1/en
Publication of WO2013047761A1 publication Critical patent/WO2013047761A1/en

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    • 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
    • F01L1/02—Valve drive
    • F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/30—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for crankshafts; for camshafts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C3/00—Shafts; Axles; Cranks; Eccentrics
    • F16C3/02—Shafts; Axles
    • F16C3/023—Shafts; Axles made of several parts, e.g. by welding

Definitions

  • the present invention relates to a method for manufacturing a camshaft for an internal combustion engine, and more particularly to a method for manufacturing a camshaft formed by diffusion bonding a cam lobe made of sintered alloy powder and a steel shaft.
  • a camshaft for an internal combustion engine a cast iron camshaft integrally formed by casting, a sintered camshaft in which a sintered cam lobe is joined to a steel shaft, or the like has been used.
  • the cast iron camshaft is relatively inexpensive, there are problems in manufacturing such as difficulty in weight reduction and difficulty in forming the cam portion with high accuracy.
  • the cast iron camshaft can only use a castable material, and it is difficult to make the cam portion excellent in wear resistance. Therefore, in the case of a cast iron camshaft, wear characteristics such as pitting resistance and scuffing resistance are inferior, and it has been difficult to cope with high performance and light weight of an internal combustion engine.
  • the sintered camshaft can select an alloy component according to the performance required for the cam, and can hollow the shaft. For this reason, sintered camshafts with sintered cam lobes joined to steel shafts have high wear resistance, and are lighter camshafts that can withstand high surface pressures and high loads. It can be suitably used for the required internal combustion engine.
  • Patent Document 1 Japanese Patent Application Laid-Open No. 2001-271909
  • a shaft and assembly suitably used for an assembling camshaft formed by diffusion bonding a cam lobe made of sintered alloy powder and a shaft made of steel.
  • a method of manufacturing a camshaft is disclosed.
  • the camshaft of Patent Document 1 is formed by compacting a shaft obtained by subjecting a high carbon chromium bearing steel material to spheroidizing and annealing, and then drawing to a predetermined size, and sintered alloy powder.
  • a cam lobe formed on a compacted body of a predetermined size is manufactured, the cam lobe is assembled to the shaft, and they are manufactured by diffusion bonding.
  • Patent Document 1 in the manufacture of assembled camshaft, the cooling after passing through the sintering furnace, by going through the steps, especially the cooling rate in the vicinity of A 1 transformation point as 10 ⁇ 20 ° C. / min, It is disclosed that it is a pearlite-based matrix structure containing fine precipitated carbides (see paragraph 0024).
  • the present invention does not cause individual differences in the cooling speed of the camshaft depending on the mounting position in the cooling device, and cools the entire circumference of the camshaft almost uniformly, thereby preventing pitting resistance and scuffing resistance. It is an object of the present invention to provide a method for manufacturing a camshaft for an internal combustion engine that can stably obtain the effect of improving wear characteristics such as the above.
  • a method of manufacturing a camshaft for an internal combustion engine includes a heat treatment step of heating a camshaft formed by assembling a sintered cam piece to a shaft body of a steel pipe to a sintering temperature by a heat treatment device;
  • a method of manufacturing a camshaft for an internal combustion engine comprising a cooling processing step of cooling the heat-treated camshaft by a cooling processing device.
  • a graphite plate provided around the cooling processing device is used.
  • the heat treatment step is preferably performed at a temperature controlled at a sintering temperature of 900 ° C. to 1200 ° C. during the sintering.
  • the first stage cooling treatment step may be performed by cooling between 700 ° C. and 900 ° C. at a cooling rate of 10 ° C./min to 30 ° C./min. preferable.
  • the second stage cooling treatment step is performed at a cooling rate of 30 ° C./min to 300 ° C./minute from the temperature after the completion of the first stage cooling treatment step. It is preferable to cool at a speed of minutes.
  • the internal combustion engine camshaft manufacturing method in the cooling processing step, is subjected to a cooling process in a state of being loaded in a plurality of mounting jigs stacked in a plurality of stages. Is preferred.
  • the cooling treatment is performed in a state where the periphery of the sintered camshaft disposed in the cooling device is surrounded by the graphite plate. It is possible to provide a camshaft for an internal combustion engine in which the effect of improving wear characteristics such as scuffing is stably achieved.
  • FIG. 2 is a cross-sectional view taken along line A-A ′ of FIG. 1. It is explanatory drawing from the front cross section for demonstrating the cooling device of FIG.
  • a method for manufacturing a camshaft for an internal combustion engine a heat treatment step of heating a camshaft formed by assembling a sintered cam piece to a shaft body of a steel pipe to a sintering temperature with a heat treatment device;
  • a method of manufacturing a camshaft for an internal combustion engine comprising: a cooling processing step of cooling the heat-treated camshaft by a cooling processing device, wherein the cooling processing step is surrounded by a graphite plate provided around the cooling processing device.
  • FIG. 1 is a front view for explaining a continuous sintering furnace used in the method for manufacturing a camshaft for an internal combustion engine according to the present invention.
  • FIG. 2 is a cross-sectional view taken along the line A-A ′ of FIG.
  • FIG. 3 is a front sectional view for explaining the cooling device of FIG.
  • a continuous sintering furnace 1 used in a method for manufacturing a camshaft for an internal combustion engine according to the present invention includes a vacuum standby chamber 2, a preheating device 3 for dewaxing, and a sintering device for sintering. 4 and the cooling device 5.
  • an inlet door 11 for carrying in the camshaft before processing and an outlet door 12 for carrying out the camshaft after processing are driven up and down by opening and closing devices 13 and 14, respectively. It has become.
  • Reference numerals 15 to 20 in the figure also indicate opening / closing devices, respectively, for driving up and down each door (not shown) partitioning each chamber.
  • a conveying roller 21 for conveying the camshaft W is provided over the entire length of the continuous sintering furnace 1.
  • the conveyance roller 21 has a cylindrical shape, and is disposed in the furnace through the entrance door 11 and the exit door 12 so that the axis of the conveyance roller 21 is horizontal and parallel to the front-rear direction.
  • a plurality of such conveying rollers 21 are arranged at the same height and at an interval narrower than the length in the conveying direction of the jig J on which the camshaft W is loaded.
  • each of the transport rollers 21 is supported so as to be rotatable about the axis of the roller. For example, all the rollers can be rotated in the same direction and at the same rotational speed by a chain (not shown) using a motor (not shown) as a power source.
  • the continuous sintering furnace 1 used in the present invention mounts the camshaft W on the conveying roller 21 and heats or cools the camshaft W while gradually moving the camshaft W forward by the rotation of the conveying roller 21. This is a method that applies
  • the heat treatment process and the cooling process in the present invention will be specifically described below.
  • the heat treatment process in the method for manufacturing a camshaft for an internal combustion engine according to the embodiment of the present invention will be described.
  • the camshaft W is carried into the continuous sintering furnace 1 through the carry-in entrance with the entrance door 11 of the continuous sintering furnace 1.
  • the carried camshaft W is carried into the preheating heating chamber 3 by the rotation of the conveying roller 21 serving as conveying means, and is heated to, for example, 500 to 700 ° C. to evaporate and remove the previously added wax.
  • the camshaft W that has been processed in the preheating device 3 is carried into the sintering device 4 and heated to a sintering temperature of 900 to 1200 ° C. to be sintered.
  • the camshaft W after the sintering process is finished is cooled in the cooling device 5 and carried out from the outlet door 12 of the continuous sintering furnace 1.
  • the preheating device 3 and the sintering device 4 provided in the continuous sintering furnace 1 used in the heat treatment process of the present invention are provided with heat sources (not shown) on the upper, lower, left and right surfaces of the camshaft W.
  • the continuous sintering furnace 1 used in the heat treatment process of the present invention employs a roller hearth type, whereby the heat of the heat source disposed on the bottom surface between adjacent rollers can be directly transmitted to the camshaft W.
  • the continuous sintering furnace 1 used in the heat treatment process of the present invention performs the same processing as a batch-type sintering furnace that employs a method in which, for example, a carriage carrying a plurality of camshafts is moved to sequentially perform heat treatment. Although it is possible, the sintering time can be shortened.
  • the cooling device 5 used in the cooling treatment process of the present invention is continuously arranged on the camshaft W carry-out side of the heat treatment device in the continuous sintering furnace 1.
  • the loading door 59 for loading W and the exit door 12 for unloading the camshaft W are opened and closed, and the cooling device 5 can be sealed by closing these doors.
  • the cooling device 5 according to the present invention can uniformly cool all of the plurality of camshafts W loaded on the jig J by performing cooling in a state where the inside is pressurized.
  • the cooling device 5 used in the present invention has a structure in which a graphite plate 51 is provided so as to surround all the camshafts W loaded on the jig J, and heat insulation by the graphite plate 51 during the cooling process, and Each camshaft can be cooled at a uniform speed without any individual difference without being affected by the mounting position of the camshaft W on the jig J by the heat radiation action.
  • the cooling device 5 used in the cooling processing step of the present invention is a system in which the cooling processing is performed in a state in which the graphite plate 51 is provided so as to surround all the camshafts W loaded on the jig J.
  • the graphite refers to a lump of carbon that can be formed by high-temperature heat treatment called graphitization.
  • the graphite material is porous, and the air existing inside absorbs heat and functions as a heat insulating material.
  • the graphite itself has a good thermal conductivity (high thermal conductivity), so it can be used for heat dissipation and cooling. It can also be suitably used for a floor board or the like.
  • the graphite plate 51 that surrounds the camshaft W in the cooling device 5 used in the cooling process of the present invention also acts as a heat storage body, can prevent partial overcooling of the camshaft W, and By suppressing the heat radiation from the camshaft W by increasing the temperature, the temperature difference due to the arrangement position of the camshaft W can be reduced.
  • cooling device 5 used in the cooling processing step of the present invention cooling can be performed at a uniform speed with respect to all the camshafts W in the cooling chamber 52, and mechanical portions are partially formed on the camshafts W.
  • the graphite plate is porous and air permeable, it is considered that these effects can be obtained.
  • a porous ceramic plate having excellent thermal conductivity can be used instead. I can do it.
  • a fan 53 is provided inside the cooling device 5 used in the cooling processing step of the present invention and is rotated by a motor stored in the fan driving device M, so that it is not shown.
  • the cooling gas introduced from the cooling gas inlet can be circulated in the cooling processing chamber 52.
  • a heat exchanger 55 that distributes the heat of the refrigerant introduced from the refrigerant introduction pipe 56 and exchanges the heat and leads the refrigerant through the refrigerant outlet pipe 57 is installed in the cooling processing chamber 52.
  • the cooling device 5 used in the cooling processing step of the present invention has such a structure, it is cooled each time the cooling gas or air circulating in the cooling processing chamber 52 comes into contact with the heat exchanger 55 and performs a rapid cooling process. I can do it.
  • a rectifying plate 58 is provided in the cooling processing chamber 52 for efficiently convectively circulating the introduced cooling gas.
  • the fan 53 can change the circulation speed when the cooling gas is circulated. For example, the fan 53 can be controlled between a state where the fan speed is 0 Hz, which is a state where the cooling gas is not circulated, and a state where the fan speed is 20 Hz to 60 Hz. In FIG.
  • the fan 53 is configured and arranged to send the cooling gas from the side, but is not limited to this position. Moreover, what pressurized nitrogen, argon, helium etc. can be used for the cooling gas used at the cooling treatment process of this invention, for example.
  • the cooling device 5 used in the cooling treatment process of the present invention can impart desired mechanical characteristics to the camshaft by adopting the above-described method.
  • the method for manufacturing a camshaft for an internal combustion engine according to the present invention employs a two-stage cooling method in the cooling process, and has a pearlite-based base structure excellent in wear characteristics such as pitting resistance and scuffing resistance. upon that, so that changing the cooling speed of the camshaft before and after the temperature in the vicinity of a 1 transformation point.
  • the heat treatment step is preferably performed at a temperature controlled at a sintering temperature of 900 ° C. to 1200 ° C. during the sintering.
  • the sintering temperature applied to the sintered camshaft is usually in the temperature range between 900 ° C. and 1200 ° C., although it varies slightly depending on the composition of the sintered alloy powder used. Therefore, the sintering apparatus 4 used in the heat treatment process of the present invention is evacuated and energized to each heat source provided in the apparatus, and the temperature in the furnace is set to a predetermined temperature between 900 ° C. and 1200 ° C. By holding, the camshaft W is sintered. Incidentally, when the sintering temperature is 900 ° C.
  • the heat source used as a heat source on the four surfaces of the camshaft W in a heat processing process is employ
  • the first stage cooling treatment step is to cool between 700 ° C. and 900 ° C. at a cooling rate of 10 ° C./min to 30 ° C./min. Is preferred.
  • the cooling rate is less than 10 ° C./min, the cooling becomes too slow, the crystal structure becomes pearlite, and the strength is lowered, which is not preferable.
  • the cooling rate exceeds 30 ° C./min, the amount of retained austenite in the crystal structure becomes excessive and the toughness tends to decrease, which is not preferable.
  • the method for manufacturing a camshaft for an internal combustion engine according to the present invention includes cooling at a cooling rate of 10 ° C./min to 30 ° C./min between 700 ° C. and 900 ° C. in the first stage cooling treatment step. Generation of deformation due to cooling of the camshaft can be suppressed. Therefore, according to the method for manufacturing a camshaft for an internal combustion engine according to the present invention, it is not necessary to perform machining or the like so that the camshaft W has a predetermined size after being cooled, and the manufacturing cost can be reduced. It will be. Note that the 700 ° C.
  • the cooling device 5 used in the cooling process of the present invention performs the cooling process with the graphite plate 51 provided so as to surround all the camshafts W loaded on the jig J as described above.
  • the camshaft can be uniformly cooled in a short time, unlike the case where the atmosphere in the cooling device is allowed to cool in a state where natural convection hardly acts. Therefore, according to the method for manufacturing a camshaft for an internal combustion engine according to the present invention, a camshaft excellent in wear characteristics such as pitting resistance and scuffing resistance can be obtained in a short time.
  • the temperature range from 600 ° C. to the following temperature range where the risk of occurrence of cooling distortion is low is set to a cooling rate of 30 ° C./min to 300 ° C./min. Cooling at a high speed can significantly reduce the cooling processing time.
  • the cooling device 5 used in the cooling processing step of the present invention includes the heat exchanger 57 in the cooling processing chamber 52 and increases the rotation speed of the fan 52 to improve the cooling efficiency. It is possible to further improve the cooling efficiency by maximizing the circulation speed of the cooling gas in the chamber 52.
  • the cooling device 5 used in the cooling processing step of the present invention employs a method of performing the cooling processing in a state where the graphite plate 51 is provided so as to surround all the camshafts W loaded on the jig J. By doing so, it becomes possible to cool all the camshafts at a uniform speed.
  • the temperature range from 600 ° C. is cooled at a cooling rate of 30 ° C./min to 300 ° C./min until the temperature of the camshaft for the internal combustion engine reaches 200 ° C., After that, even if it is allowed to cool, it has no effect on the product quality, but rather reduces the manufacturing cost.
  • the internal combustion engine camshaft manufacturing method in the cooling processing step, the internal combustion engine camshaft is cooled in a state of being loaded in a plurality of mounting jigs stacked in multiple stages. Is preferred.
  • a plurality of camshafts W are horizontally placed so that the heat treatment and cooling of the sintered camshaft can be improved. It is preferable to process at a time in a state where a plurality of mounting plates are stacked. However, when a plurality of camshafts W are processed at the same time, a temperature difference is likely to occur depending on the position where they are placed. In particular, in order to obtain a desired mechanical property, the entire circumference of the camshaft W is as uniform as possible in the cooling process. Cooling is required.
  • the cooling device 5 used in the cooling process of the present invention since the graphite plate can be arranged on the bottom side even during the cooling process by adopting the roller hearth type, all the camshafts W It becomes possible to control the cooling rate of each of them without individual differences.
  • a large number of camshafts W having excellent wear characteristics such as pitting resistance and scuffing resistance can be manufactured in a single process.
  • the manufacturing cost can be reduced.
  • a camshaft having particularly high mechanical strength can be provided stably.
  • the camshaft produced by the manufacturing method of the present invention can reduce the diameter of the shaft or reduce the thickness of the hollow type shaft while maintaining excellent durability. , Can achieve its weight reduction.
  • the cooling process which takes a relatively long time compared to the heat treatment, can be shortened, so that each process can proceed efficiently.
  • the continuous sintering furnace 1 employs the method for manufacturing a camshaft for an internal combustion engine according to the present invention, so that the camshaft W is moved by the transport roller 21 so as to sequentially move the processing devices 2 to 5.
  • the camshaft W can be moved efficiently in the direction of the arrow shown in FIG.
  • the manufacturing cost can be reduced, so that high quality and high mechanical strength are required. It can be suitably employed for the sliding element.

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  • Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
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  • Thermal Sciences (AREA)
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  • Valve-Gear Or Valve Arrangements (AREA)

Abstract

In order to provide a method for manufacturing a camshaft with which it is possible to reliably obtain improvements in wear characteristics such as pitting resistance and scuffing resistance, a method for manufacturing a camshaft for an internal combustion engine is equipped with a heating process step wherein a camshaft which is formed by assembling the cam piece of a sintered material to the shaft main body of a steel pipe is heated to sintering temperature by a heating process device, and a cooling process step, wherein the camshaft which has undergone the heating process is cooled by means of a cooling process device. In addition, in the cooling process the cooling is performed by a two-stage process comprising a first-stage cooling process, whereby the camshaft is arranged within the cooling process device in a state wherein the camshaft is surrounded by graphite plates provided at the periphery of the cooling process device, after which slow cooling is performed, and a second-stage cooling process, whereby a cooling gas that has been introduced into the cooling process device is circulated by a fan and rapid cooling is performed.

Description

内燃機関用カムシャフトの製造方法Method for manufacturing camshaft for internal combustion engine
　本件発明は、内燃機関用カムシャフトの製造方法に関し、具体的には焼結合金粉末からなるカムロブと鋼製のシャフトとを拡散接合により形成されるカムシャフトの製造方法に関する。 The present invention relates to a method for manufacturing a camshaft for an internal combustion engine, and more particularly to a method for manufacturing a camshaft formed by diffusion bonding a cam lobe made of sintered alloy powder and a steel shaft.
　従来より、内燃機関用のカムシャフトには、鋳造により一体成形された鋳鉄カムシャフトや、焼結材のカムロブを鋼製シャフトに接合した焼結カムシャフト等が用いられている。ここで、鋳鉄カムシャフトは、比較的安価であるものの、軽量化が困難であったり、カム部を高い精度で形成することが困難である等の製造上の問題がある。更に、鋳鉄カムシャフトは、鋳造可能な材料しか用いることが出来ず、カム部を耐摩耗性に優れたものとすることが困難である。従って、鋳鉄カムシャフトの場合、耐ピッチング性や耐スカッフィング性等の摩耗特性が劣り、内燃機関の高性能化や軽量化に対応することが困難となっていた。これに対し、焼結カムシャフトは、カムに要求される性能に応じて合金成分を選択可能であり、また、シャフトを中空化することが出来る。そのため、焼結材のカムロブを鋼製シャフトに接合した焼結カムシャフトは、高い耐摩耗性を有し、高面圧、高負荷に耐えられる軽量のカムシャフトとして、高性能化や軽量化が求められる内燃機関に好適に用いることが出来る。 Conventionally, as a camshaft for an internal combustion engine, a cast iron camshaft integrally formed by casting, a sintered camshaft in which a sintered cam lobe is joined to a steel shaft, or the like has been used. Here, although the cast iron camshaft is relatively inexpensive, there are problems in manufacturing such as difficulty in weight reduction and difficulty in forming the cam portion with high accuracy. Furthermore, the cast iron camshaft can only use a castable material, and it is difficult to make the cam portion excellent in wear resistance. Therefore, in the case of a cast iron camshaft, wear characteristics such as pitting resistance and scuffing resistance are inferior, and it has been difficult to cope with high performance and light weight of an internal combustion engine. On the other hand, the sintered camshaft can select an alloy component according to the performance required for the cam, and can hollow the shaft. For this reason, sintered camshafts with sintered cam lobes joined to steel shafts have high wear resistance, and are lighter camshafts that can withstand high surface pressures and high loads. It can be suitably used for the required internal combustion engine.
　例えば、特許文献１（特開２００１－２７１９０９号）には、焼結合金粉末からなるカムロブと、鋼材からなるシャフトとを拡散接合して形成される組立式カムシャフトに好適に用いられるシャフトおよび組立式カムシャフトの製造方法について開示されている。具体的には、特許文献１のカムシャフトは、高炭素クロム軸受鋼鋼材を球状化焼き鈍し処理し、その後引き抜き加工して所定の寸法に加工したシャフトと、焼結合金粉末を圧粉成形して所定の寸法の圧粉成形体に形成したカムロブとを作製し、当該カムロブを当該シャフトに組み付け、それらを拡散接合して製造されるものである。なお、特許文献１には、組立式カムシャフトの製造において、焼結炉を通過した後の冷却を、特にＡ１変態点付近の冷却速度を１０～２０℃／分として段階を経ることによって、微細な析出炭化物を含んだパーライト主体の基地組織とする旨開示している（段落００２４参照のこと。）。 For example, in Patent Document 1 (Japanese Patent Application Laid-Open No. 2001-271909), a shaft and assembly suitably used for an assembling camshaft formed by diffusion bonding a cam lobe made of sintered alloy powder and a shaft made of steel. A method of manufacturing a camshaft is disclosed. Specifically, the camshaft of Patent Document 1 is formed by compacting a shaft obtained by subjecting a high carbon chromium bearing steel material to spheroidizing and annealing, and then drawing to a predetermined size, and sintered alloy powder. A cam lobe formed on a compacted body of a predetermined size is manufactured, the cam lobe is assembled to the shaft, and they are manufactured by diffusion bonding. In Patent Document 1, in the manufacture of assembled camshaft, the cooling after passing through the sintering furnace, by going through the steps, especially the cooling rate in the vicinity of A 1 transformation point as 10 ~ 20 ° C. / min, It is disclosed that it is a pearlite-based matrix structure containing fine precipitated carbides (see paragraph 0024).
特開２００１－２７１９０９号公報JP 2001-271909 A
　しかし、特許文献１には、カムシャフトの冷却工程において、当該カムシャフトの全周を均一に同じ速度で冷却する方法に関して何らの開示もされていない。仮に、カムシャフトの全周が均一に同じ速度で冷却されないとすれば、当該カムシャフトの部分部分で機械的特性にバラツキが生じて、品質の低下を招いてしまう。ちなみに、カムシャフトの製造に用いる焼結炉は、一般的に、カムシャフトの焼結を行う焼結装置と、焼結されたカムシャフトの冷却を行う冷却装置とを備えている。そして、これら焼結装置及び冷却装置では、処理効率上、カムシャフトを例えば水平横置きにして複数載置した載置プレートを複数段積み重ねた状態で治具に載置した状態で、順次搬送されて処理が施される。焼結カムシャフトを焼結温度以上の温度から冷却する場合には、冷却装置の冷却処理室内に冷却ガスを循環させて強制冷却を行うことが多いが、当該冷却ガスの循環速度を低下させても、カムシャフトの載置位置が内側と外側とにおいて冷却速度に個体差が生じてしまう。 However, Patent Document 1 does not disclose any method for cooling the entire circumference of the camshaft uniformly at the same speed in the camshaft cooling process. If the entire circumference of the camshaft is not uniformly cooled at the same speed, the mechanical characteristics of the portions of the camshaft vary and the quality is degraded. Incidentally, a sintering furnace used for manufacturing a camshaft generally includes a sintering device for sintering the camshaft and a cooling device for cooling the sintered camshaft. In these sintering devices and cooling devices, for processing efficiency, for example, the camshaft is horizontally transported in a state where it is mounted on a jig in a state where a plurality of mounting plates are stacked horizontally and stacked in a plurality of stages. Are processed. When the sintering camshaft is cooled from a temperature higher than the sintering temperature, forced cooling is often performed by circulating a cooling gas in the cooling processing chamber of the cooling device, but the circulation speed of the cooling gas is reduced. However, there is an individual difference in the cooling rate between the camshaft mounting position on the inner side and the outer side.
　以上のことから、本件発明は、冷却装置内における載置位置によってカムシャフトの冷却速度に個体差が生じることがなく、カムシャフトの全周をほぼ均一に冷却し、耐ピッチング性や耐スカッフィング性等の摩耗特性の向上効果を安定して得られる内燃機関用カムシャフトの製造方法の提供を目的とする。 From the above, the present invention does not cause individual differences in the cooling speed of the camshaft depending on the mounting position in the cooling device, and cools the entire circumference of the camshaft almost uniformly, thereby preventing pitting resistance and scuffing resistance. It is an object of the present invention to provide a method for manufacturing a camshaft for an internal combustion engine that can stably obtain the effect of improving wear characteristics such as the above.
　そこで、本発明者等は、鋭意研究を行った結果、カムシャフトの焼結後の冷却処理について所定の条件を満たすことで、上述した課題を解決するに到った。以下、本件発明に関して説明する。 Therefore, as a result of intensive studies, the present inventors have solved the above-mentioned problems by satisfying predetermined conditions for the cooling treatment after sintering of the camshaft. Hereinafter, the present invention will be described.
　本件発明に係る内燃機関用カムシャフトの製造方法は、鋼製パイプのシャフト本体に焼結材のカムピースを組み付けて形成されるカムシャフトを、加熱処理装置により焼結温度まで加熱する加熱処理工程と、加熱処理されたカムシャフトを冷却処理装置により冷却する冷却処理工程とを備えた内燃機関用カムシャフトの製造方法において、当該冷却処理工程では、冷却処理装置内の周囲に設けられた黒鉛板で包囲された状態にカムシャフトを配置した後に、徐冷を行う第１段階冷却処理工程と、当該冷却処理装置内に注入した冷却ガスを出来るにより循環させて急冷を行う第２段階冷却処理工程との２段階の工程で冷却するようにしたことを特徴とする。 A method of manufacturing a camshaft for an internal combustion engine according to the present invention includes a heat treatment step of heating a camshaft formed by assembling a sintered cam piece to a shaft body of a steel pipe to a sintering temperature by a heat treatment device; A method of manufacturing a camshaft for an internal combustion engine comprising a cooling processing step of cooling the heat-treated camshaft by a cooling processing device. In the cooling processing step, a graphite plate provided around the cooling processing device is used. A first stage cooling process for performing slow cooling after placing the camshaft in an enclosed state; and a second stage cooling process for performing rapid cooling by circulating the cooling gas injected into the cooling processing apparatus as much as possible. It is characterized by cooling in the two-stage process.
　本件発明に係る内燃機関用カムシャフトの製造方法において、前記加熱処理工程は、焼結を行うに際し焼結温度が９００℃～１２００℃として制御した温度で加熱することが好ましい。 In the method for manufacturing a camshaft for an internal combustion engine according to the present invention, the heat treatment step is preferably performed at a temperature controlled at a sintering temperature of 900 ° C. to 1200 ° C. during the sintering.
　本件発明に係る内燃機関用カムシャフトの製造方法において、前記第１段階冷却処理工程は、７００℃～９００℃の間を冷却速度１０℃／分～３０℃／分の速さで冷却することが好ましい。 In the method for manufacturing a camshaft for an internal combustion engine according to the present invention, the first stage cooling treatment step may be performed by cooling between 700 ° C. and 900 ° C. at a cooling rate of 10 ° C./min to 30 ° C./min. preferable.
　本件発明に係る内燃機関用カムシャフトの製造方法において、前記第２段階冷却処理工程は、前記第１段階冷却処理工程終了後の温度から以下の温度領域を冷却速度３０℃／分～３００℃／分の速さで冷却することが好ましい。 In the method for manufacturing a camshaft for an internal combustion engine according to the present invention, the second stage cooling treatment step is performed at a cooling rate of 30 ° C./min to 300 ° C./minute from the temperature after the completion of the first stage cooling treatment step. It is preferable to cool at a speed of minutes.
　本件発明に係る内燃機関用カムシャフトの製造方法において、前記冷却処理工程では、前記内燃機関用カムシャフトを複数段に段積みされた載置用治具に複数積載した状態で冷却処理を行うことが好ましい。 In the internal combustion engine camshaft manufacturing method according to the present invention, in the cooling processing step, the internal combustion engine camshaft is subjected to a cooling process in a state of being loaded in a plurality of mounting jigs stacked in a plurality of stages. Is preferred.
　本件発明に係る内燃機関用カムシャフトの製造方法によれば、冷却装置内に配置された焼結カムシャフトの周囲を黒鉛板で包囲された状態で冷却処理を行うことで、耐ピッチング性や耐スカッフィング性等の摩耗特性の向上効果が安定して図られた内燃機関用カムシャフトを提供することが出来る。 According to the method for manufacturing a camshaft for an internal combustion engine according to the present invention, the cooling treatment is performed in a state where the periphery of the sintered camshaft disposed in the cooling device is surrounded by the graphite plate. It is possible to provide a camshaft for an internal combustion engine in which the effect of improving wear characteristics such as scuffing is stably achieved.
本件発明に係る内燃機関用カムシャフトの製造方法で用いる連続焼結炉を説明するために例示した正面図である。It is the front view illustrated in order to demonstrate the continuous sintering furnace used with the manufacturing method of the cam shaft for internal combustion engines which concerns on this invention. 図１のＡ－Ａ’断面図である。FIG. 2 is a cross-sectional view taken along line A-A ′ of FIG. 1. 図１の冷却装置を説明するための正面断面からの説明図である。It is explanatory drawing from the front cross section for demonstrating the cooling device of FIG.
　本件発明に係る内燃機関用カムシャフトの製造方法の好ましい実施の形態について、以下に図を用いて示しながら本件発明をより詳細に説明する。 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a method for manufacturing a camshaft for an internal combustion engine according to the present invention will be described in detail with reference to the drawings.
　本件発明に係る内燃機関用カムシャフトの製造方法：　鋼製パイプのシャフト本体に焼結材のカムピースを組み付けて形成されるカムシャフトを、加熱処理装置により焼結温度まで加熱する加熱処理工程と、加熱処理されたカムシャフトを冷却処理装置により冷却する冷却処理工程とを備えた内燃機関用カムシャフトの製造方法において、当該冷却処理工程では、冷却処理装置内の周囲に設けられた黒鉛板で包囲された状態にカムシャフトを配置した後に、徐冷を行う第１段階冷却処理工程と、当該冷却処理装置内に注入した冷却ガスをファンにより循環させて急冷を行う第２段階冷却処理工程との２段階の工程で冷却するようにしたことを特徴とするものである。 A method for manufacturing a camshaft for an internal combustion engine according to the present invention: a heat treatment step of heating a camshaft formed by assembling a sintered cam piece to a shaft body of a steel pipe to a sintering temperature with a heat treatment device; A method of manufacturing a camshaft for an internal combustion engine, comprising: a cooling processing step of cooling the heat-treated camshaft by a cooling processing device, wherein the cooling processing step is surrounded by a graphite plate provided around the cooling processing device. After the camshaft is disposed in the state, a first stage cooling process for performing slow cooling, and a second stage cooling process for performing rapid cooling by circulating the cooling gas injected into the cooling processing apparatus with a fan. It is characterized by cooling in a two-stage process.
　図１は、本件発明に係る内燃機関用カムシャフトの製造方法で用いる連続焼結炉を説明するための正面図である。また、図２は、図１のＡ－Ａ’断面図である。また、図３は、図１の冷却装置を説明するための正面断面からの説明図である。本件発明に係る内燃機関用カムシャフトの製造方法で用いる連続焼結炉１は、図１に例示するように、真空待機室２、脱ワックスを行う予備加熱装置３、焼結を行う焼結装置４、冷却装置５とで構成することが出来る。図１に示す連続焼結炉１は、処理前のカムシャフト搬入用の入口扉１１と、処理後のカムシャフト搬出用の出口扉１２とが、それぞれ開閉装置１３及び１４により昇降駆動されるようになつている。なお、図中１５～２０に関しても、それぞれ開閉装置を示したものであり、各室を区画する各扉（不図示）の昇降駆動を行うものである。そして、連続焼結炉１の全長に亘って、カムシャフトＷを搬送するための搬送用ロ－ラ２１が設けられている。 FIG. 1 is a front view for explaining a continuous sintering furnace used in the method for manufacturing a camshaft for an internal combustion engine according to the present invention. FIG. 2 is a cross-sectional view taken along the line A-A ′ of FIG. FIG. 3 is a front sectional view for explaining the cooling device of FIG. As illustrated in FIG. 1, a continuous sintering furnace 1 used in a method for manufacturing a camshaft for an internal combustion engine according to the present invention includes a vacuum standby chamber 2, a preheating device 3 for dewaxing, and a sintering device for sintering. 4 and the cooling device 5. In the continuous sintering furnace 1 shown in FIG. 1, an inlet door 11 for carrying in the camshaft before processing and an outlet door 12 for carrying out the camshaft after processing are driven up and down by opening and closing devices 13 and 14, respectively. It has become. Reference numerals 15 to 20 in the figure also indicate opening / closing devices, respectively, for driving up and down each door (not shown) partitioning each chamber. A conveying roller 21 for conveying the camshaft W is provided over the entire length of the continuous sintering furnace 1.
　ここで、搬送ローラ２１は、円柱形状を呈し、当該搬送ローラ２１の軸が水平且つ前後方向に平行になるように入口扉１１と出口扉１２とを貫通して炉体内に配置される。このような搬送ローラ２１が、同じ高さで、カムシャフトＷを積載した治具Ｊの搬送方向長さよりも狭い間隔で複数並設される。また、搬送ローラ２１は、それぞれ、ローラの軸を中心として回転自在に支持されている。そして、例えばモータ（不図示）を動力源としてチェーン（不図示）によって全てのローラが同じ方向に、同じ回転速度で回転する構成とすることが出来る。本件発明で用いる連続焼結炉１は、このような搬送ローラ２１上にカムシャフトＷを載置し、搬送ローラ２１の回転によってカムシャフトＷを徐々に前方に移動させながら、加熱処理や冷却処理を施す方式を採用したものである。 Here, the conveyance roller 21 has a cylindrical shape, and is disposed in the furnace through the entrance door 11 and the exit door 12 so that the axis of the conveyance roller 21 is horizontal and parallel to the front-rear direction. A plurality of such conveying rollers 21 are arranged at the same height and at an interval narrower than the length in the conveying direction of the jig J on which the camshaft W is loaded. Further, each of the transport rollers 21 is supported so as to be rotatable about the axis of the roller. For example, all the rollers can be rotated in the same direction and at the same rotational speed by a chain (not shown) using a motor (not shown) as a power source. The continuous sintering furnace 1 used in the present invention mounts the camshaft W on the conveying roller 21 and heats or cools the camshaft W while gradually moving the camshaft W forward by the rotation of the conveying roller 21. This is a method that applies
　以上をふまえ、以下に本件発明における加熱処理工程及び冷却処理工程について、具体的に説明していく。まず最初に、本件発明の実施の形態に係る内燃機関用カムシャフトの製造方法における加熱処理工程に関して説明する。本件発明の加熱処理工程では、まず、カムシャフトＷが連続焼結炉１の入口扉１１のある搬入口を通り連続式焼結炉１の内部に搬入される。そして、搬入されたカムシャフトＷは、搬送手段である搬送ローラ２１の回転によって、予熱加熱室３内に搬入され、例えば５００～７００℃まで加熱されて予め添加されているワックスを蒸発除去する。そして、予備加熱装置３での処理が行われたカムシャフトＷは、焼結装置４内に搬入され、焼結温度である９００～１２００℃まで加熱され焼結処理される。焼結処理が終了した後のカムシャフトＷは、冷却装置５において冷却され、連続焼結炉１の出口扉１２から搬出される。 Based on the above, the heat treatment process and the cooling process in the present invention will be specifically described below. First, the heat treatment process in the method for manufacturing a camshaft for an internal combustion engine according to the embodiment of the present invention will be described. In the heat treatment process of the present invention, first, the camshaft W is carried into the continuous sintering furnace 1 through the carry-in entrance with the entrance door 11 of the continuous sintering furnace 1. The carried camshaft W is carried into the preheating heating chamber 3 by the rotation of the conveying roller 21 serving as conveying means, and is heated to, for example, 500 to 700 ° C. to evaporate and remove the previously added wax. Then, the camshaft W that has been processed in the preheating device 3 is carried into the sintering device 4 and heated to a sintering temperature of 900 to 1200 ° C. to be sintered. The camshaft W after the sintering process is finished is cooled in the cooling device 5 and carried out from the outlet door 12 of the continuous sintering furnace 1.
　なお、本件発明の加熱処理工程で用いる、連続焼結炉１に備わる予備加熱装置３、及び焼結装置４は、カムシャフトＷの上下左右の四面に熱源（不図示）が設けられる。本件発明の加熱処理工程で用いる連続焼結炉１は、ローラハース式を採用することで、隣接するローラの間から底面に配設した熱源の熱を直接的にカムシャフトＷに伝えることが出来る。その結果、本件発明の加熱処理工程で用いる連続焼結炉１によれば、治具Ｊ上に積載された全てのカムシャフトＷに対して均一に加熱処理を行うことが出来、焼結温度に対して±１０℃の範囲で温度制御を行うことが可能となる。従って、本件発明の加熱処理工程で用いる連続焼結炉１は、例えば複数のカムシャフトを積載した台車を移動させて順次加熱処理を行う方式を採用したバッチ式焼結炉と同様に処理を行うことが可能でありながらも、焼結時間を短縮することが出来る。 In addition, the preheating device 3 and the sintering device 4 provided in the continuous sintering furnace 1 used in the heat treatment process of the present invention are provided with heat sources (not shown) on the upper, lower, left and right surfaces of the camshaft W. The continuous sintering furnace 1 used in the heat treatment process of the present invention employs a roller hearth type, whereby the heat of the heat source disposed on the bottom surface between adjacent rollers can be directly transmitted to the camshaft W. As a result, according to the continuous sintering furnace 1 used in the heat treatment process of the present invention, all the camshafts W loaded on the jig J can be uniformly heat-treated, and the sintering temperature is increased. On the other hand, temperature control can be performed within a range of ± 10 ° C. Therefore, the continuous sintering furnace 1 used in the heat treatment process of the present invention performs the same processing as a batch-type sintering furnace that employs a method in which, for example, a carriage carrying a plurality of camshafts is moved to sequentially perform heat treatment. Although it is possible, the sintering time can be shortened.
　次に、本件発明の実施の形態に係る内燃機関用カムシャフトの製造方法における冷却処理工程に関して説明する。図２及び図３に示すように、本件発明の冷却処理工程で用いる冷却装置５は、連続焼結炉１において加熱処理装置のカムシャフトＷ搬出口側に連続して配置されており、カムシャフトＷを搬入する搬入扉５９と、カムシャフトＷを搬出する出口扉１２とが開閉する構成を備え、これら扉を閉じることで冷却装置５内を密閉状態とすることが出来る構造を備えている。本件発明の冷却装置５は、その内部を加圧させた状態で冷却を行うことで、治具Ｊに積載された複数のカムシャフトＷ全てに対して均一に冷却処理を行うことが出来る。なお、本件発明で用いる冷却装置５は、治具Ｊに積載されたカムシャフトＷ全てを包囲するように黒鉛製の板５１を設けた構造を備え、冷却処理時の黒鉛板５１による断熱、及び放熱作用によってカムシャフトＷの治具Ｊ上の載置位置に影響されずに個体差無く各カムシャフトを均一な速度で冷却することが出来る。 Next, the cooling process in the method for manufacturing a camshaft for an internal combustion engine according to the embodiment of the present invention will be described. As shown in FIGS. 2 and 3, the cooling device 5 used in the cooling treatment process of the present invention is continuously arranged on the camshaft W carry-out side of the heat treatment device in the continuous sintering furnace 1. The loading door 59 for loading W and the exit door 12 for unloading the camshaft W are opened and closed, and the cooling device 5 can be sealed by closing these doors. The cooling device 5 according to the present invention can uniformly cool all of the plurality of camshafts W loaded on the jig J by performing cooling in a state where the inside is pressurized. The cooling device 5 used in the present invention has a structure in which a graphite plate 51 is provided so as to surround all the camshafts W loaded on the jig J, and heat insulation by the graphite plate 51 during the cooling process, and Each camshaft can be cooled at a uniform speed without any individual difference without being affected by the mounting position of the camshaft W on the jig J by the heat radiation action.
　本件発明の冷却処理工程で用いる冷却装置５は、上述したように、治具Ｊに積載されたカムシャフトＷ全てを包囲するように黒鉛製の板５１を設けた状態で冷却処理を行う方式を採用している。ここで、黒鉛とは、黒鉛化という高温熱処理をされることにより出来るカーボンの塊をいう。黒鉛素材は、多孔質であり、内部に存在する空気が熱を吸収して断熱材として機能する他、黒鉛自身の熱伝導率が良い（熱伝導性が高い）性質により、放熱・冷却用の敷板等にも好適に用いることが出来る。すなわち、本件発明の冷却処理工程で用いる冷却装置５内でカムシャフトＷを囲う黒鉛板５１は、蓄熱体としても作用し、カムシャフトＷの部分的な過冷却を防止出来ると共に、黒鉛板自身の昇温によりカムシャフトＷからの熱放射を抑制することで、カムシャフトＷの配置位置による温度差を小さくすることが出来る。この結果、本件発明の冷却処理工程で用いる冷却装置５によれば、冷却室５２内におけるカムシャフトＷ全てに関して均一な速度で冷却を行うことが出来ることとなり、カムシャフトＷの部分部分で機械的特性にばらつきが生じて製品品質の低下を招くこともない。ちなみに、黒鉛板は、多孔質で通気性を有することから、これらの効果を得ることが可能になると考えられ、この点に鑑みれば多孔質で熱伝導性に優れるセラミックス製の板等でも代用することが出来る。 As described above, the cooling device 5 used in the cooling processing step of the present invention is a system in which the cooling processing is performed in a state in which the graphite plate 51 is provided so as to surround all the camshafts W loaded on the jig J. Adopted. Here, the graphite refers to a lump of carbon that can be formed by high-temperature heat treatment called graphitization. The graphite material is porous, and the air existing inside absorbs heat and functions as a heat insulating material. Also, the graphite itself has a good thermal conductivity (high thermal conductivity), so it can be used for heat dissipation and cooling. It can also be suitably used for a floor board or the like. That is, the graphite plate 51 that surrounds the camshaft W in the cooling device 5 used in the cooling process of the present invention also acts as a heat storage body, can prevent partial overcooling of the camshaft W, and By suppressing the heat radiation from the camshaft W by increasing the temperature, the temperature difference due to the arrangement position of the camshaft W can be reduced. As a result, according to the cooling device 5 used in the cooling processing step of the present invention, cooling can be performed at a uniform speed with respect to all the camshafts W in the cooling chamber 52, and mechanical portions are partially formed on the camshafts W. There is no variation in the characteristics and no deterioration in product quality. Incidentally, since the graphite plate is porous and air permeable, it is considered that these effects can be obtained. In view of this point, a porous ceramic plate having excellent thermal conductivity can be used instead. I can do it.
　また、図２に示すように、本件発明の冷却処理工程で用いる冷却装置５の内部には、ファン５３が設けられ、ファン駆動装置Ｍに格納されているモータにより回転させられることで、図示せぬ冷却ガス導入口より導入される冷却ガスを冷却処理室５２内に循環させることが出来る。また、本件発明の冷却処理工程で用いる冷却装置５では、冷媒導入管５６から導入した冷媒を分配して熱交換させ、冷媒導出管５７より導出させる熱交換器５５を冷却処理室５２内に設置することも出来る。本件発明の冷却処理工程で用いる冷却装置５は、このような構造とした場合、冷却処理室５２内を循環する冷却ガスや空気が熱交換器５５に接触する毎に冷やされて急冷処理を行うことが出来る。また、冷却処理室５２内には、導入されてきた冷却ガスを効率良く対流循環させるための整流板５８が設けられる。そして、ファン５３は、冷却ガスを循環させる際の循環速度を変更することが出来る。例えば、ファン５３は、冷却ガスを循環させない状態であるファン回転数０Ｈｚの状態から、ファン回転数２０Ｈｚ～６０Ｈｚの状態の間で制御可能である。なお、図２では、ファン５３は、冷却ガスを側方より送るよう構成配置されているが、この位置に限定されるものではない。また、本件発明の冷却処理工程で用いる冷却ガスは、例えば、窒素、アルゴン、ヘリウム等を加圧したものを用いることが出来る。 Further, as shown in FIG. 2, a fan 53 is provided inside the cooling device 5 used in the cooling processing step of the present invention and is rotated by a motor stored in the fan driving device M, so that it is not shown. The cooling gas introduced from the cooling gas inlet can be circulated in the cooling processing chamber 52. Further, in the cooling device 5 used in the cooling processing step of the present invention, a heat exchanger 55 that distributes the heat of the refrigerant introduced from the refrigerant introduction pipe 56 and exchanges the heat and leads the refrigerant through the refrigerant outlet pipe 57 is installed in the cooling processing chamber 52. You can also When the cooling device 5 used in the cooling processing step of the present invention has such a structure, it is cooled each time the cooling gas or air circulating in the cooling processing chamber 52 comes into contact with the heat exchanger 55 and performs a rapid cooling process. I can do it. Further, a rectifying plate 58 is provided in the cooling processing chamber 52 for efficiently convectively circulating the introduced cooling gas. The fan 53 can change the circulation speed when the cooling gas is circulated. For example, the fan 53 can be controlled between a state where the fan speed is 0 Hz, which is a state where the cooling gas is not circulated, and a state where the fan speed is 20 Hz to 60 Hz. In FIG. 2, the fan 53 is configured and arranged to send the cooling gas from the side, but is not limited to this position. Moreover, what pressurized nitrogen, argon, helium etc. can be used for the cooling gas used at the cooling treatment process of this invention, for example.
　本件発明の冷却処理工程で用いる冷却装置５は、上述したような方式を採用することで、カムシャフトに所望の機械的特性を付与させることが出来る。また、本件発明に係る内燃機関用カムシャフトの製造方法は、冷却処理工程において二段階冷却方式を採用しており、耐ピッチング性や耐スカッフィング性等の摩耗特性に優れたパーライト主体の基地組織とするに際し、Ａ１変態点付近の温度の前後で当該カムシャフトの冷却速度を変えるようにしている。例えば、本件発明の冷却処理工程においては、Ａ１変態点付近の温度を通過する直前までをファンの回転数が２０Ｈｚ～３０Ｈｚとなるように設定して徐冷することで、温度分布の不均一が生じることによるカムシャフトの変形を抑制し、Ａ１変態点付近の温度を通過した後をファンの回転数が３０Ｈｚ～６０Ｈｚとなるように設定して急冷することでサイクル時間の短縮を図ることが出来る。 The cooling device 5 used in the cooling treatment process of the present invention can impart desired mechanical characteristics to the camshaft by adopting the above-described method. In addition, the method for manufacturing a camshaft for an internal combustion engine according to the present invention employs a two-stage cooling method in the cooling process, and has a pearlite-based base structure excellent in wear characteristics such as pitting resistance and scuffing resistance. upon that, so that changing the cooling speed of the camshaft before and after the temperature in the vicinity of a 1 transformation point. For example, in the cooling process of the present invention, by slow cooling set so until just before passing through the temperature near the A 1 transformation point rotational speed of the fan becomes 20 Hz ~ 30 Hz, unevenness of temperature distribution possible to suppress the deformation of the camshaft, shorten that cycle time for rapid cooling by setting after passing through the temperature around the a 1 transformation point as the rotation speed of the fan is 30 Hz ~ 60 Hz due to occur I can do it.
　また、本件発明の内燃機関用カムシャフトの製造方法において、加熱処理工程は、焼結を行うに際し焼結温度が９００℃～１２００℃として制御した温度で加熱することが好ましい。 In the method for manufacturing a camshaft for an internal combustion engine of the present invention, the heat treatment step is preferably performed at a temperature controlled at a sintering temperature of 900 ° C. to 1200 ° C. during the sintering.
　本件発明の加熱処理工程において、焼結カムシャフトに施される焼結温度は、用いる焼結合金粉末の成分組成により若干異なるが、通常９００℃～１２００℃の間の温度領域である。従って、本件発明の加熱処理工程で用いる焼結装置４は、その内部を真空状態として、装置内部に備わる各熱源に通電し、炉内の温度を９００℃～１２００℃の間の所定の温度に保持することで、カムシャフトＷは焼結される。ちなみに、焼結温度が９００℃以下になると、金属粒子の拡散結合に時間を費やしたり又は拡散結合が不十分となるため、カムシャフトＷの品質を安定させることが出来ない。そして、本件発明に係る内燃機関用カムシャフトの製造方法では、ローラハース式連続炉を採用することで、上述したように、加熱処理工程においてカムシャフトＷの上下左右の４面に熱源となる熱源を設けることが出来るため、カムシャフトＷの載置位置に関係なく焼結温度に対して±１０℃の範囲で温度制御を行うことが可能となる。従って、本件発明に係る内燃機関用カムシャフトの製造方法によれば、焼結処理においてカムシャフトを構成するシャフトとカムロブとの拡散接合を適切に行うことが出来る。 In the heat treatment step of the present invention, the sintering temperature applied to the sintered camshaft is usually in the temperature range between 900 ° C. and 1200 ° C., although it varies slightly depending on the composition of the sintered alloy powder used. Therefore, the sintering apparatus 4 used in the heat treatment process of the present invention is evacuated and energized to each heat source provided in the apparatus, and the temperature in the furnace is set to a predetermined temperature between 900 ° C. and 1200 ° C. By holding, the camshaft W is sintered. Incidentally, when the sintering temperature is 900 ° C. or lower, it takes time for the diffusion bonding of the metal particles or the diffusion bonding becomes insufficient, so that the quality of the camshaft W cannot be stabilized. And in the manufacturing method of the camshaft for internal combustion engines which concerns on this invention, as mentioned above, the heat source used as a heat source on the four surfaces of the camshaft W in a heat processing process is employ | adopted by employ | adopting a roller hearth type continuous furnace. Therefore, the temperature can be controlled within a range of ± 10 ° C. with respect to the sintering temperature regardless of the mounting position of the camshaft W. Therefore, according to the method for manufacturing a camshaft for an internal combustion engine according to the present invention, diffusion bonding between the shaft constituting the camshaft and the cam lobe can be appropriately performed in the sintering process.
　また、本件発明に係る内燃機関用カムシャフトの製造方法において、第１段階冷却処理工程は、７００℃～９００℃の間を冷却速度１０℃／分～３０℃／分の速さで冷却することが好ましい。この冷却速度が１０℃／分未満の場合には、冷却が緩やかになりすぎて、結晶組織がパーライト化し、強度が低下するため好ましくない。一方、この冷却速度が３０℃／分を超えると、結晶組織内の残留オーステナイト量が過剰となり、靱性が低下する傾向にあるため好ましくない。 In the method for manufacturing a camshaft for an internal combustion engine according to the present invention, the first stage cooling treatment step is to cool between 700 ° C. and 900 ° C. at a cooling rate of 10 ° C./min to 30 ° C./min. Is preferred. When the cooling rate is less than 10 ° C./min, the cooling becomes too slow, the crystal structure becomes pearlite, and the strength is lowered, which is not preferable. On the other hand, when the cooling rate exceeds 30 ° C./min, the amount of retained austenite in the crystal structure becomes excessive and the toughness tends to decrease, which is not preferable.
　本件発明に係る内燃機関用カムシャフトの製造方法は、第１段階冷却処理工程において、７００℃～９００℃の間を冷却速度１０℃／分～３０℃／分の速さで冷却することで、カムシャフトの冷却による変形の発生を抑制することが出来る。そのため、本件発明に係る内燃機関用カムシャフトの製造方法によれば、カムシャフトＷを冷却処理した後に所定の寸法になるように機械加工等を行う必要がなく、製造コストを低減させることが出来ることとなる。なお、７００℃～９００℃は、上述したＡ１変態点付近の温度を含み、オーステナイト状態の鋼や鉄系焼結材を徐冷（冷却速度：約２０℃／分）したときにパーライト組織に変化する温度領域である。また、本件発明の冷却処理工程で用いる冷却装置５は、上述したように、治具Ｊに積載したカムシャフトＷ全てを包囲するように黒鉛製の板５１を設けた状態で冷却処理を行うため、従来の冷却処理のように、冷却装置内雰囲気を自然対流がほとんど作用しない状態で放冷する場合と異なり、短時間でカムシャフトを均一に冷却することが可能となる。従って、本件発明に係る内燃機関用カムシャフトの製造方法によれば、短時間で耐ピッチング性や耐スカッフィング性等の摩耗特性に優れたカムシャフトを得ることが出来る。 The method for manufacturing a camshaft for an internal combustion engine according to the present invention includes cooling at a cooling rate of 10 ° C./min to 30 ° C./min between 700 ° C. and 900 ° C. in the first stage cooling treatment step. Generation of deformation due to cooling of the camshaft can be suppressed. Therefore, according to the method for manufacturing a camshaft for an internal combustion engine according to the present invention, it is not necessary to perform machining or the like so that the camshaft W has a predetermined size after being cooled, and the manufacturing cost can be reduced. It will be. Note that the 700 ° C. ~ 900 ° C., wherein the temperature in the vicinity of A 1 transformation point as described above, the steel or iron-based sintered material of the austenitic state slow cooling (cooling rate: about 20 ° C. / min) and pearlite structure when the This is a changing temperature range. In addition, the cooling device 5 used in the cooling process of the present invention performs the cooling process with the graphite plate 51 provided so as to surround all the camshafts W loaded on the jig J as described above. Unlike the conventional cooling process, the camshaft can be uniformly cooled in a short time, unlike the case where the atmosphere in the cooling device is allowed to cool in a state where natural convection hardly acts. Therefore, according to the method for manufacturing a camshaft for an internal combustion engine according to the present invention, a camshaft excellent in wear characteristics such as pitting resistance and scuffing resistance can be obtained in a short time.
　また、本件発明に係る内燃機関用カムシャフトの製造方法において、第２段階冷却処理工程は、第１段階冷却処理工程終了後の温度から以下の温度領域を冷却速度３０℃／分～３００℃／分の速さで冷却することが好ましい。 Further, in the method for manufacturing a camshaft for an internal combustion engine according to the present invention, the second stage cooling process includes the following temperature range from the temperature after the completion of the first stage cooling process to a cooling rate of 30 ° C./min to 300 ° C. / It is preferable to cool at a speed of minutes.
　本件発明に係る内燃機関用カムシャフトの製造方法は、第２段階冷却処理工程において、冷却歪み発生の危険性が少ない６００℃から以下の温度領域を冷却速度３０℃／分～３００℃／分の速さで冷却することで、冷却処理時間を大幅に短縮することが出来る。本件発明の冷却処理工程で用いる冷却装置５は、上述したように、冷却効率の向上を図るべく、冷却処理室５２内に熱交換器５７を備えると共に、ファン５２の回転速度を上げて冷却処理室５２内の冷却ガスの循環速度を最大限とすることで、更なる冷却効率の向上を図ることも可能である。この場合においても、本件発明の冷却処理工程で用いる冷却装置５は、治具Ｊに積載したカムシャフトＷ全てを包囲するように黒鉛製の板５１を設けた状態で冷却処理を行う方式を採用することで、全てのカムシャフトを均一の速度で冷却することが可能となる。なお、内燃機関用カムシャフトの場合、６００℃から以下の温度領域を冷却速度３０℃／分～３００℃／分の速さで、内燃機関用カムシャフトの温度が２００℃に達するまで冷却し、その後は、放冷しても製品品質に何ら影響はなく、むしろ製造コストの削減となる。 In the method for manufacturing the camshaft for an internal combustion engine according to the present invention, in the second stage cooling treatment step, the temperature range from 600 ° C. to the following temperature range where the risk of occurrence of cooling distortion is low is set to a cooling rate of 30 ° C./min to 300 ° C./min. Cooling at a high speed can significantly reduce the cooling processing time. As described above, the cooling device 5 used in the cooling processing step of the present invention includes the heat exchanger 57 in the cooling processing chamber 52 and increases the rotation speed of the fan 52 to improve the cooling efficiency. It is possible to further improve the cooling efficiency by maximizing the circulation speed of the cooling gas in the chamber 52. Even in this case, the cooling device 5 used in the cooling processing step of the present invention employs a method of performing the cooling processing in a state where the graphite plate 51 is provided so as to surround all the camshafts W loaded on the jig J. By doing so, it becomes possible to cool all the camshafts at a uniform speed. In the case of a camshaft for an internal combustion engine, the temperature range from 600 ° C. is cooled at a cooling rate of 30 ° C./min to 300 ° C./min until the temperature of the camshaft for the internal combustion engine reaches 200 ° C., After that, even if it is allowed to cool, it has no effect on the product quality, but rather reduces the manufacturing cost.
　また、本件発明に係る内燃機関用カムシャフトの製造方法において、冷却処理工程では、内燃機関用カムシャフトを複数段に段積みされた載置用治具に複数積載した状態で冷却処理を行うことが好ましい。 In the internal combustion engine camshaft manufacturing method according to the present invention, in the cooling processing step, the internal combustion engine camshaft is cooled in a state of being loaded in a plurality of mounting jigs stacked in multiple stages. Is preferred.
　本件発明の加熱処理工程及び冷却処理工程では、図３に示すように、焼結カムシャフトの加熱処理及び冷却処理を、処理効率の向上が図れるよう、例えばカムシャフトＷを水平横置きにして複数載置した載置プレートを複数段積み重ねた状態で一度に処理することが好ましい。但し、カムシャフトＷは、複数同時に処理するに際し、載置される位置によって温度差が生じやすく、特に所望の機械的性質を得るために冷却処理においてカムシャフトＷの全周を極力均一な速度で冷却することが必要とされる。しかし、上述したように、本件発明の冷却処理工程で用いる冷却装置５によれば、ローラハース式を採用することで、冷却処理時においても底面側に黒鉛板を配置出来るため、全てのカムシャフトＷの冷却速度を個体差なく制御することが可能となる。 In the heat treatment process and the cooling process of the present invention, as shown in FIG. 3, for example, a plurality of camshafts W are horizontally placed so that the heat treatment and cooling of the sintered camshaft can be improved. It is preferable to process at a time in a state where a plurality of mounting plates are stacked. However, when a plurality of camshafts W are processed at the same time, a temperature difference is likely to occur depending on the position where they are placed. In particular, in order to obtain a desired mechanical property, the entire circumference of the camshaft W is as uniform as possible in the cooling process. Cooling is required. However, as described above, according to the cooling device 5 used in the cooling process of the present invention, since the graphite plate can be arranged on the bottom side even during the cooling process by adopting the roller hearth type, all the camshafts W It becomes possible to control the cooling rate of each of them without individual differences.
　以上のことから、本件発明に係る内燃機関用カムシャフトの製造方法によれば、一度の処理で耐ピッチング性や耐スカッフィング性等の摩耗特性に優れたカムシャフトＷを多数製造することが出来、製造コストの削減を図ることが出来る。 From the above, according to the method for manufacturing a camshaft for an internal combustion engine according to the present invention, a large number of camshafts W having excellent wear characteristics such as pitting resistance and scuffing resistance can be manufactured in a single process. The manufacturing cost can be reduced.
　以上、本件発明に係る内燃機関用カムシャフトの製造方法によれば、特に高い機械的強度を備えたカムシャフトを安定して提供することが出来る。その結果、本件発明の製造方法により作製されたカムシャフトは、シャフトの径を小さくしたり、中空タイプのシャフトにおいてはその肉厚を薄くすることが可能となり、優れた耐久性能を維持させたまま、その軽量化を達成することが出来る。また、本件発明に係るカムシャフトの製造方法によれば、加熱処理よりも比較的時間の要する冷却処理を短縮することが出来るため、効率良く各処理を進めることが出来る。言い換えれば、連続式焼結炉１は、本件発明に係る内燃機関用カムシャフトの製造方法を採用することで、各処理装置２～５を順次移動するように搬送ローラ２１によりカムシャフトＷを移動（図１に示す矢印方向）させる際に効率よくカムシャフトＷを移動させることが出来るようになる。その結果、本件発明係る内燃機関用カムシャフトの製造方法によれば、製造コストの低減化を図ることが出来るため、高い品質と高い機械的強度が要求される、例えば内燃機関に用いられる他の摺動要素にも好適に採用することが可能となる。 As described above, according to the method for manufacturing a camshaft for an internal combustion engine according to the present invention, a camshaft having particularly high mechanical strength can be provided stably. As a result, the camshaft produced by the manufacturing method of the present invention can reduce the diameter of the shaft or reduce the thickness of the hollow type shaft while maintaining excellent durability. , Can achieve its weight reduction. Further, according to the method for manufacturing a camshaft according to the present invention, the cooling process, which takes a relatively long time compared to the heat treatment, can be shortened, so that each process can proceed efficiently. In other words, the continuous sintering furnace 1 employs the method for manufacturing a camshaft for an internal combustion engine according to the present invention, so that the camshaft W is moved by the transport roller 21 so as to sequentially move the processing devices 2 to 5. The camshaft W can be moved efficiently in the direction of the arrow shown in FIG. As a result, according to the method for manufacturing a camshaft for an internal combustion engine according to the present invention, the manufacturing cost can be reduced, so that high quality and high mechanical strength are required. It can be suitably employed for the sliding element.
１　　連続式焼結炉
２　　待機室
３　　予備加熱装置
４　　焼結装置
５　　冷却装置
２１　搬送ローラ
１１　入口扉
１２　出口扉
５１　黒鉛板
５２　冷却処理室
５３　ファン
５４　集風誘導ダクト
５５　熱交換器
５６　冷媒導入管
５７　冷媒導出管
５８　整流板
５９　搬入扉
Ｊ　　治具
Ｍ　　ファン駆動用モータ装置
Ｗ　　カムシャフト DESCRIPTION OF SYMBOLS 1 Continuous sintering furnace 2 Standby chamber 3 Preheating apparatus 4 Sintering apparatus 5 Cooling apparatus 21 Conveying roller 11 Inlet door 12 Outlet door 51 Graphite plate 52 Cooling processing chamber 53 Fan 54 Wind collection induction duct 55 Heat exchanger 56 Refrigerant introduction Pipe 57 Refrigerant outlet pipe 58 Rectifier plate 59 Carry-in door J Jig M Fan drive motor device W Camshaft

Claims (5)

  1. 　鋼製パイプのシャフト本体に焼結材のカムピースを組み付けて形成されるカムシャフトを、加熱処理装置により焼結温度まで加熱する加熱処理工程と、
    　加熱処理されたカムシャフトを冷却処理装置により冷却する冷却処理工程とを備えた内燃機関用カムシャフトの製造方法において、
    　当該冷却処理工程では、冷却処理装置内の周囲に設けられた黒鉛板で包囲された状態にカムシャフトを配置した後に、徐冷を行う第１段階冷却処理工程と、
    　当該冷却処理装置内に注入した冷却ガスをファンにより循環させて急冷を行う第２段階冷却処理工程との２段階の工程で冷却するようにしたことを特徴とする内燃機関用カムシャフトの製造方法。     A heat treatment step of heating a camshaft formed by assembling a cam piece of a sintered material to a shaft body of a steel pipe to a sintering temperature by a heat treatment device;
    A method of manufacturing a camshaft for an internal combustion engine, comprising: a cooling treatment step of cooling the heat-treated camshaft by a cooling treatment device;
    In the cooling processing step, a first stage cooling processing step of performing slow cooling after arranging the camshaft in a state surrounded by a graphite plate provided around the inside of the cooling processing device,
    A method of manufacturing a camshaft for an internal combustion engine, wherein the cooling gas injected into the cooling processing apparatus is cooled in a two-stage process including a second-stage cooling process process in which the cooling gas is circulated by a fan and rapidly cooled. .
  2. 　前記加熱処理工程は、焼結を行うに際し焼結温度が９００℃～１２００℃として制御した温度で加熱する請求項１に記載の内燃機関用カムシャフトの製造方法。 The method for manufacturing a camshaft for an internal combustion engine according to claim 1, wherein in the heat treatment step, the sintering is performed at a temperature controlled at a sintering temperature of 900 ° C to 1200 ° C.
  3. 　前記第１段階冷却処理工程は、７００℃～９００℃の間を冷却速度１０℃／分～３０℃／分の速さで冷却する請求項１又は請求項２に記載の内燃機関用カムシャフトの製造方法。 3. The camshaft for an internal combustion engine according to claim 1, wherein the first stage cooling treatment step cools between 700 ° C. and 900 ° C. at a cooling rate of 10 ° C./min to 30 ° C./min. Production method.
  4. 　前記第２段階冷却処理工程は、前記第１段階冷却処理工程終了後の温度から以下の温度領域を冷却速度３０℃／分～３００℃／分の速さで冷却する請求項１～請求項３のいずれかに記載の内燃機関用カムシャフトの製造方法。 The second stage cooling treatment step cools the following temperature region from the temperature after completion of the first stage cooling treatment step at a cooling rate of 30 ° C / min to 300 ° C / min. A method for manufacturing a camshaft for an internal combustion engine according to any one of the above.
  5. 　前記冷却処理工程では、前記内燃機関用カムシャフトを複数段に段積みされた載置用治具に複数積載した状態で冷却処理を行う請求項１～請求項４のいずれかに記載の内燃機関用カムシャフトの製造方法。 The internal combustion engine according to any one of claims 1 to 4, wherein in the cooling process step, the internal combustion engine camshaft is cooled in a state where a plurality of the camshafts for the internal combustion engine are stacked on a plurality of mounting jigs. Method for manufacturing a camshaft.
PCT/JP2012/075109 2011-09-30 2012-09-28 Method for manufacturing camshaft for internal combustion engine WO2013047761A1 (en)

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