WO2013046446A1 - Cooling device - Google Patents

Cooling device Download PDF

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Publication number
WO2013046446A1
WO2013046446A1 PCT/JP2011/072599 JP2011072599W WO2013046446A1 WO 2013046446 A1 WO2013046446 A1 WO 2013046446A1 JP 2011072599 W JP2011072599 W JP 2011072599W WO 2013046446 A1 WO2013046446 A1 WO 2013046446A1
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WO
WIPO (PCT)
Prior art keywords
cooling
cooling device
workpieces
workpiece
present
Prior art date
Application number
PCT/JP2011/072599
Other languages
French (fr)
Japanese (ja)
Inventor
隆 舩橋
俊輔 竹口
Original Assignee
日本ピストンリング株式会社
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 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 PCT/JP2011/072599 priority Critical patent/WO2013046446A1/en
Priority to PCT/JP2012/075110 priority patent/WO2013047762A1/en
Priority to KR1020147007130A priority patent/KR101580241B1/en
Priority to JP2013536433A priority patent/JP6078000B2/en
Publication of WO2013046446A1 publication Critical patent/WO2013046446A1/en

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    • 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
    • C21D11/00—Process control or regulation for heat treatments
    • C21D11/005—Process control or regulation for heat treatments for cooling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/003—Apparatus, e.g. furnaces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/10—Sintering only
    • B22F3/1017—Multiple heating or additional steps
    • B22F3/1028—Controlled cooling
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/62—Quenching devices
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • C21D1/767—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material with forced gas circulation; Reheating thereof
    • 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
    • C21D9/0056—Furnaces through which the charge is moved in a horizontal straight path
    • 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
    • C21D9/0062—Heat-treating apparatus with a cooling or quenching zone
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/02—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity of multiple-track type; of multiple-chamber type; Combinations of furnaces
    • F27B9/028—Multi-chamber type furnaces
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/04—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity adapted for treating the charge in vacuum or special atmosphere
    • F27B9/045—Furnaces with controlled atmosphere
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/14—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment
    • F27B9/20—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment the charge moving in a substantially straight path tunnel furnace
    • F27B9/24—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment the charge moving in a substantially straight path tunnel furnace being carried by a conveyor
    • F27B9/2407—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment the charge moving in a substantially straight path tunnel furnace being carried by a conveyor the conveyor being constituted by rollers (roller hearth furnace)
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/30—Details, accessories, or equipment peculiar to furnaces of these types
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D7/00—Forming, maintaining, or circulating atmospheres in heating chambers
    • F27D7/04—Circulating atmospheres by mechanical means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D9/00—Cooling of furnaces or of charges therein

Definitions

  • the present invention relates to a cooling device used in a continuous sintering furnace in which a metal powder is heated and sintered.
  • a continuous sintering furnace used for sintering a metal powder molded product generally includes a sintering device for sintering a workpiece and a cooling device for cooling the sintered workpiece.
  • the continuous sintering furnace the workpieces are sequentially conveyed to these apparatuses to be processed.
  • a cooling gas is introduced into the cooling device, and the cooling gas is circulated by a fan provided in the cooling device to cool the workpiece due to radiant heat loss. It was.
  • Patent Document 1 Japanese Patent Laid-Open No. 3-257119 discloses a roller hearth type vacuum furnace that heats an object to be processed in a vacuum state.
  • the roller hearth vacuum furnace disclosed in Patent Document 1 is “a roller hearth vacuum furnace in which a cooling device is provided on the outlet side of a heating chamber that heats the workpiece in a vacuum state.
  • a plurality of nozzles for ejecting a cooling gas are provided on the side of the conveyance path, and a rotary table that is rotated around a vertical axis is provided in the cooling device with a conveyance roller for conveying the workpiece on the upper surface.
  • the cooling gas ejected from the nozzle is sprayed on the object to be processed which is transported from the heating chamber and placed on the turntable ”(refer to claim 1).
  • Japanese Patent Laid-Open No. 3-257119 discloses a roller hearth type vacuum furnace that heats an object to be processed in a vacuum state.
  • the roller hearth type vacuum furnace according to Patent Document 1 circulates a cooling gas by a fan in a cooling device that accommodates a material to be processed, and performs a cooling process by heat exchange between the cooling gas and the material to be processed.
  • the cooling rate varies depending on the arrangement positions of the objects to be processed.
  • the cooling rate varies even in a portion of the workpiece, and the mechanical characteristics of the product are not stabilized, leading to a reduction in product quality.
  • an object of the present invention is to provide a cooling device capable of uniforming the cooling rate of the workpiece charged in the cooling treatment chamber provided in the continuous sintering furnace.
  • the present inventors have solved the above-mentioned problems by satisfying predetermined conditions for a cooling device used in a continuous sintering furnace that heats and sinters metal powder. Arrived.
  • the present invention will be described.
  • the cooling device is a roller hearth type in which a plurality of workpieces loaded on a mounting jig stacked in a plurality of stages are conveyed by a plurality of arranged rollers to sequentially perform a heating process and a cooling process.
  • the cooling device includes a cooling device that can be sealed in a state in which a plurality of heat-treated workpieces are accommodated, a decompression device that decompresses the cooling device, and a cooling gas in the cooling device.
  • a cooling fan capable of adjusting the circulation speed, a heat exchanger for cooling the cooling gas, and a graphite plate arranged so as to surround the plurality of works inside the cooling device. It is characterized by that.
  • the workpiece is preferably a camshaft for an internal combustion engine.
  • the graphite plate is disposed so as to surround all of the plurality of workpieces placed on the jig, so that all of the heat-treated workpieces can be made at a uniform speed. And since it can cool in a short time, the quality improvement of the said workpiece
  • FIG. 2 is a cross-sectional view taken along line A-A ′ of FIG. 1. It is front sectional drawing for demonstrating the cooling device of FIG.
  • Cooling device A roller hearth-type continuous furnace in which a plurality of workpieces loaded on a mounting jig stacked in a plurality of stages are conveyed by a plurality of rollers arranged in parallel and sequentially subjected to heat treatment and cooling treatment
  • the cooling device includes a cooling device that can be sealed in a state in which a plurality of heat-treated workpieces are accommodated, a decompression device that depressurizes the cooling device, and circulating a cooling gas in the cooling device. And a cooling fan whose circulation speed can be adjusted, a heat exchanger for cooling the cooling gas, and a graphite plate arranged so as to surround the plurality of workpieces inside the cooling device. It is a feature.
  • FIG. 1 is a longitudinal sectional view for explaining a continuous sintering furnace according to an embodiment of 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 including a cooling device 5 according to the present invention includes a vacuum standby chamber 2, a preheating device 3 that performs dewaxing, a sintering device 4 that performs sintering, and a cooling device. 5 can be configured.
  • a transfer roller 21 for transferring the workpiece 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 transport rollers 21 are arranged at the same height and at an interval narrower than the transport direction length of the jig J on which the workpiece 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 provided with the cooling device 5 according to the present invention places the workpiece W on such a conveyance roller 21 and gradually moves the workpiece W forward by the rotation of the conveyance roller 21. A method of applying a cooling process is adopted.
  • the workpiece W is carried into the continuous sintering furnace 1 through a carry-in entrance having the entrance door 11 for carrying in the continuous sintering furnace 1.
  • the loaded work W is carried into the preheating chamber 3 by the rotation of the carrying roller 21 serving as a carrying means, and is heated to, for example, 500 to 700 ° C. to evaporate and remove the previously added wax.
  • the workpiece W that has been processed in the preheating device 3 is carried into the sintering device 4 and heated to a sintering temperature of 950 to 1120 ° C. to be sintered.
  • the workpiece W after the sintering process is finished is cooled by the cooling device 5 and carried out from the outlet door 12 for carrying out.
  • the preheating device 3 and the sintering device 4 provided in the continuous sintering furnace 1 of the present invention are provided with heat sources (not shown) on the upper, lower, left and right surfaces of the workpiece W.
  • the continuous sintering furnace 1 of the present invention employs a roller hearth type, so that the heat of the heat source disposed on the bottom surface between adjacent rollers can be directly transmitted to the workpiece W. As a result, according to the continuous sintering furnace 1 of the present invention, it is possible to uniformly heat all the workpieces W loaded on the jig J.
  • the cooling device 5 according to the present invention has a configuration in which a loading door 59 for loading the workpiece W and an outlet door 12 illustrated in FIG. 1 for unloading the workpiece W are opened and closed. It has a structure that can close the inside of the cooling device 5 by closing the door.
  • the cooling device 5 of the present invention can uniformly cool all the plurality of workpieces W loaded on the jig J by performing cooling in a state where the inside is pressurized.
  • the cooling device 5 is connected via a pressurizing device (not shown) that pressurizes the inside of the cooling processing chamber 52, and during the cooling processing, the pressure in the cooling processing chamber 52 is a predetermined value of about 1500 TORR. It is possible to control the pressurization up to the pressure.
  • the cooling process chamber 52 is pressurized to reduce the difference in cooling rate at each location of the circulating cooling gas compared to the atmospheric pressure state. It can be made.
  • the cooling device 5 since the cooling device 5 according to the present invention has a structure in which the graphite plate 51 is provided so as to surround all the workpieces W loaded on the jig J, the heat insulating action by the graphite plate 51 during the cooling process, In addition, the work can be cooled at a uniform speed without any individual difference without being affected by the placement position of the work W on the jig J by the heat radiation action. Further, the cooling device 10 according to the present invention has the graphite plate 51 disposed therein, so that the cooling gas does not directly contact the workpiece W disposed in the cooling processing chamber 52, and the workpiece W Even in the case of rapid cooling, it is possible to cool at a uniform speed.
  • the cooling device 5 is provided with the graphite plate 51 so as to surround all the workpieces W loaded on the jig J, and a system for performing the cooling process in this state is provided.
  • 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 workpiece W in the cooling device 5 of the present invention also acts as a heat storage body, can prevent partial overcooling of the workpiece W, and from the workpiece W by the temperature rise of the graphite plate itself. By suppressing the heat radiation, the temperature difference due to the arrangement position of the workpiece W can be reduced. As a result, according to the cooling device 5 of the present invention, it is possible to cool all the workpieces W in the cooling chamber 52 at a uniform speed, resulting in variations in mechanical characteristics in the portions of the workpieces W and products. There is no loss of 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.
  • the cooling device 5 has a fan 53 provided therein and is rotated by a motor stored in the fan driving device M, thereby introducing a cooling gas (not shown).
  • the cooling gas introduced from the mouth can be circulated in the cooling processing chamber 52.
  • the heat exchanger 55 that distributes the heat introduced from the refrigerant introduction pipe 56 and exchanges heat, and leads the heat through the refrigerant lead-out pipe 57 can be installed in the cooling processing chamber 52. .
  • the cooling device or cooling air circulating in the cooling processing chamber 52 is cooled each time it contacts the heat exchanger 55 and can be rapidly cooled.
  • 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.
  • 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. Therefore, according to the cooling device according to the present invention, the cooling process speed of the workpiece W can be improved by optimizing the combination of the pressure state in the cooling process chamber 52 and the fan rotation speed condition. The desired mechanical characteristics can be stably imparted to the workpiece W. 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 Since the cooling device 5 according to the present invention has the above-described structure, it is possible to obtain both an excellent cooling strain suppression effect and a cooling efficiency improvement effect in a temperature region where the possibility of occurrence of cooling strain is low.
  • nitrogen gas is introduced into the cooling device 5 to restore the pressure to atmospheric pressure, and then the outlet door 12 on the carry-out side is opened and the transport roller 21 is rotated. By doing so, the workpiece W can be carried out from the cooling device 5.
  • the cooling device 5 of the present invention shows a plurality of workpieces W stacked and placed in a plurality of stages. According to the cooling device 5 of the present invention, the workpiece W can be uniformly cooled regardless of the placement position of the workpiece W. It becomes possible, and generation
  • the cooling processing time can be significantly shortened as compared with the conventional case. Therefore, among the devices constituting the continuous sintering furnace 1, the processing time is relatively long. Processing can be performed in parallel with the short preheating device 3 and the sintering device 4. Therefore, according to the continuous sintering furnace 1 provided with the cooling device 5 according to the present invention, the processing can be performed very efficiently.
  • the continuous sintering furnace 1 includes the cooling device according to the present invention, so that the workpiece W is moved by the transport roller 21 so as to sequentially move the processing devices 2 to 5 (in the direction of the arrow shown in FIG. 1). It is possible to move the workpiece W efficiently when making it.
  • the work is preferably a camshaft for an internal combustion engine.
  • Camshafts for internal combustion engines that are used under severe sliding conditions have higher wear resistance than conventional models, and are light weight that can withstand high surface pressures and loads as the internal combustion engines become more powerful and have higher output.
  • a camshaft for an internal combustion engine is required to have excellent wear characteristics such as pitting resistance and scuffing resistance that can withstand severe sliding conditions under high engine speed and high contact surface pressure.
  • a camshaft for an internal combustion engine is a so-called sintered camshaft in which a sintered cam lobe is joined to a steel shaft, and the cooling speed of the camshaft is increased in the cooling process after sintering. Control is required so that the entire circumference is uniform.
  • the cooling device 5 since the cooling device 5 according to the present invention has a structure in which the arranged graphite plate surrounds the camshaft, the camshaft can be cooled at a uniform speed without unevenness. Further, in the cooling device according to the present invention, the above-mentioned characteristics required for the camshaft are stably imparted in a short time by an optimal combination of the pressure state in the cooling processing chamber 52 and the fan rotational speed condition. It will be possible. For example, in the cooling process of the sintered camshaft, after the sintering process is completed, first, the cooling in the cooling process chamber 52 is performed at a pressure of 760 torr and the fan rotational speed is 0 Hz to 20 Hz for a predetermined time (first slow cooling mode).
  • cooling is performed for a predetermined time (second slow cooling mode) in a state where the pressure in the cooling processing chamber 52 is 910 torr and the fan rotational speed is 20 Hz to 30 Hz, and then the fan is heated in the cooling processing chamber 52 at 1500 torr.
  • Cooling mode conditions can be set such that cooling is performed for a predetermined time (rapid cooling mode) at a rotational speed of 30 Hz to 60 Hz.
  • a cooling rate of the sintered camshaft A 1 can also be varied cut before and after the temperature near the transformation point, pitting resistance and the scuffing resistance, etc.
  • a sintered camshaft excellent in wear characteristics can be provided stably in a short time.
  • the heat treatment and cooling treatment of the sintered camshaft is performed at once in a state where, for example, a plurality of placement plates stacked in a horizontal and horizontal manner are stacked in order to improve the processing efficiency. (See Work W in FIG. 3). Therefore, the temperature difference between the camshafts is likely to occur depending on the position where the camshaft is placed, and it is necessary to uniformly heat and cool the entire circumference of the camshaft during the heat treatment and the cooling treatment.
  • a heat source can be arranged on the bottom surface side in the heat treatment, and a graphite plate can be arranged on the bottom surface side in the cooling treatment as well. Therefore, the temperature of the camshaft can be controlled without individual differences.
  • the cooling device according to the present invention has a configuration in which a plurality of workpieces are surrounded and a graphite plate is disposed, so that all the workpieces can be cooled in a short time and at a uniform speed. Therefore, according to the cooling device according to the present invention, it is possible to improve the quality of the workpiece and shorten the processing time, and to reduce the manufacturing cost. From the above, the cooling device according to the present invention can be suitably used for other sliding elements used in, for example, an internal combustion engine, which require high quality and high mechanical strength.

Abstract

The objective of the present invention is to provide a cooling device that is capable of uniform cooling of an article to be processed that is inserted into a cooling process chamber provided to a continuous sintering furnace. To achieve the objective, a cooling device is adopted that is provided to a roller-hearth continuous furnace that conveys, by means of a plurality of rollers provided in parallel, a plurality of workpieces layered on a carrying tool that is stacked in a plurality of stages, and successively performs a heating process and a cooling process, wherein the cooling device is provided with: a cooling device that, in the state of housing the plurality of workpieces, can seal/enclose the plurality of workpieces that have been subjected to the heating process; a decompression device that decompresses the cooling device; a cooling fan that circulates a cooling gas within the cooling device and can adjust the circulation speed of the cooling gas; a heat exchanger for cooling the cooling gas; and a graphite plate disposed in a manner so as to encircle the plurality of workpieces within the cooling device.

Description

冷却装置Cooling system
　本件発明は、金属粉末を加熱処理して焼結させる連続式焼結炉に用いる冷却装置に関するものである。 The present invention relates to a cooling device used in a continuous sintering furnace in which a metal powder is heated and sintered.
　従来、金属粉末の成形品の焼結処理に用いられる連続焼結炉は、一般的に、ワークの焼結が行われる焼結装置と、焼結が行われたワークを冷却する冷却装置とを備えている。ここで、連続焼結炉は、これらの装置にワークが順次搬送されて処理が施されることとなる。そして、焼結処理後に行われる冷却処理では、冷却装置内に冷却用ガスを導入し、冷却装置内に設けられたファンによって当該冷却用ガスを循環させてワークの放射熱損失による冷却が行われていた。 Conventionally, a continuous sintering furnace used for sintering a metal powder molded product generally includes a sintering device for sintering a workpiece and a cooling device for cooling the sintered workpiece. I have. Here, in the continuous sintering furnace, the workpieces are sequentially conveyed to these apparatuses to be processed. In the cooling process performed after the sintering process, a cooling gas is introduced into the cooling device, and the cooling gas is circulated by a fan provided in the cooling device to cool the workpiece due to radiant heat loss. It was.
　例えば、特許文献１（特開平３－２５７１１９号）には、真空状態において被処理物の加熱を行うローラハース式真空炉について開示されている。具体的には、特許文献１のローラハース式真空炉は、「真空状態で被処理物の加熱をおこなう加熱室の出口側に冷却装置を設けたローラハース式真空炉において、前記冷却装置の被処理物搬送路の側方に、冷却用ガスを噴出する複数個のノズルを設け、被処理物を搬送する搬送用ローラを上面にそなえ鉛直軸線のまわりに回転駆動される回転台を、前記冷却装置内に設け、前記加熱室より搬送され前記回転台上に載置された被処理物に前記ノズルから噴出した冷却用ガスを吹付けるようにした」ことを特徴としたものである（請求項１参照のこと。）。 For example, Patent Document 1 (Japanese Patent Laid-Open No. 3-257119) discloses a roller hearth type vacuum furnace that heats an object to be processed in a vacuum state. Specifically, the roller hearth vacuum furnace disclosed in Patent Document 1 is “a roller hearth vacuum furnace in which a cooling device is provided on the outlet side of a heating chamber that heats the workpiece in a vacuum state. A plurality of nozzles for ejecting a cooling gas are provided on the side of the conveyance path, and a rotary table that is rotated around a vertical axis is provided in the cooling device with a conveyance roller for conveying the workpiece on the upper surface. The cooling gas ejected from the nozzle is sprayed on the object to be processed which is transported from the heating chamber and placed on the turntable ”(refer to claim 1). Of that.)
特開平３－２５７１１９号公報JP-A-3-257119
　しかし、特許文献１に係るローラハース式真空炉は、被処理材を収容する冷却装置内において、ファンにより冷却ガスを循環させ、その冷却ガスと被処理材との熱交換によって冷却処理を行うものであるが、冷却装置内に複数の被処理物が搬入されて処理する場合に、各被処理物の配置位置によって冷却速度にばらつきが生じてしまう。また、特許文献１のローラハース式真空炉では、当該被処理物の部分部分でも冷却速度にばらつきが生じ、製品の機械的特性が安定せず製品品質の低下を招いてしまう。 However, the roller hearth type vacuum furnace according to Patent Document 1 circulates a cooling gas by a fan in a cooling device that accommodates a material to be processed, and performs a cooling process by heat exchange between the cooling gas and the material to be processed. However, when a plurality of objects to be processed are carried into the cooling device for processing, the cooling rate varies depending on the arrangement positions of the objects to be processed. Further, in the roller hearth type vacuum furnace of Patent Document 1, the cooling rate varies even in a portion of the workpiece, and the mechanical characteristics of the product are not stabilized, leading to a reduction in product quality.
　以上のことから、本件発明は、連続焼結炉に備わる冷却処理室の内部に装入されたワークの冷却速度を均一とすることが可能な冷却装置の提供を目的とする。 In view of the above, an object of the present invention is to provide a cooling device capable of uniforming the cooling rate of the workpiece charged in the cooling treatment chamber provided in the continuous sintering furnace.
　そこで、本発明者等は、鋭意研究を行った結果、金属粉末を加熱処理して焼結させる連続式焼結炉に用いる冷却装置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。 Thus, as a result of earnest research, the present inventors have solved the above-mentioned problems by satisfying predetermined conditions for a cooling device used in a continuous sintering furnace that heats and sinters metal powder. Arrived. Hereinafter, the present invention will be described.
　本件発明に係る冷却装置は、複数段に段積みされた載置用治具に積載した複数のワークを、複数の並設されたローラーにより搬送して加熱処理と冷却処理とを順次行うローラハース式連続炉に備わる冷却装置において、当該冷却装置は、加熱処理を施した複数のワークを収容した状態で密閉可能な冷却装置と、当該冷却装置を減圧する減圧装置と、当該冷却装置内において冷却ガスを循環させると共に、その循環速度を調節可能な冷却ファンと、当該冷却ガスを冷却するための熱交換器と、当該冷却装置の内部に当該複数のワークを包囲するように配した黒鉛板を備えることを特徴とする。 The cooling device according to the present invention is a roller hearth type in which a plurality of workpieces loaded on a mounting jig stacked in a plurality of stages are conveyed by a plurality of arranged rollers to sequentially perform a heating process and a cooling process. In the cooling device provided in the continuous furnace, the cooling device includes a cooling device that can be sealed in a state in which a plurality of heat-treated workpieces are accommodated, a decompression device that decompresses the cooling device, and a cooling gas in the cooling device. A cooling fan capable of adjusting the circulation speed, a heat exchanger for cooling the cooling gas, and a graphite plate arranged so as to surround the plurality of works inside the cooling device. It is characterized by that.
　また、本件発明に係る冷却装置において、前記ワークは、内燃機関用カムシャフトであることが好ましい。 In the cooling device according to the present invention, the workpiece is preferably a camshaft for an internal combustion engine.
　本件発明に係る冷却装置によれば、その内部において、治具に載置された複数のワーク全てを包囲するように黒鉛板を配設することで、加熱処理されたワークを全て均一な速度で、且つ短時間で冷却することが出来るため、当該ワークの品質向上と、処理時間の短縮とを図ることが出来る。 According to the cooling device according to the present invention, the graphite plate is disposed so as to surround all of the plurality of workpieces placed on the jig, so that all of the heat-treated workpieces can be made at a uniform speed. And since it can cool in a short time, the quality improvement of the said workpiece | work and shortening of processing time can be aimed at.
本件発明に係る冷却装置を備えた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 provided with the cooling device 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図である。It is front sectional drawing for demonstrating the cooling device of FIG.
　本件発明に係る冷却装置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。 The preferred embodiment of the cooling device according to the present invention will be described below in more detail with reference to the drawings.
　本件発明に係る冷却装置：　複数段に段積みされた載置用治具に積載した複数のワークを、複数の並設されたローラーにより搬送して加熱処理と冷却処理と順次行うローラハース式連続炉に備わる冷却装置において、当該冷却装置は、加熱処理を施した複数のワークを収容した状態で密閉可能な冷却装置と、当該冷却装置を減圧する減圧装置と、当該冷却装置内において冷却ガスを循環させると共に、その循環速度を調節可能な冷却ファンと、当該冷却ガスを冷却するための熱交換器と、当該冷却装置の内部に当該複数のワークを包囲するように配した黒鉛板を備えることを特徴とするものである。 Cooling device according to the present invention: A roller hearth-type continuous furnace in which a plurality of workpieces loaded on a mounting jig stacked in a plurality of stages are conveyed by a plurality of rollers arranged in parallel and sequentially subjected to heat treatment and cooling treatment The cooling device includes a cooling device that can be sealed in a state in which a plurality of heat-treated workpieces are accommodated, a decompression device that depressurizes the cooling device, and circulating a cooling gas in the cooling device. And a cooling fan whose circulation speed can be adjusted, a heat exchanger for cooling the cooling gas, and a graphite plate arranged so as to surround the plurality of workpieces inside the cooling device. It is a feature.
　図１は、本件発明の実施の形態に係る連続焼結炉を説明するための縦断面図である。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図である。本件発明に係る冷却装置５を備えた連続焼結炉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、処理前のワーク搬入用の入口扉１１と、処理後のワーク搬出用の出口扉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、ワーク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 longitudinal sectional view for explaining a continuous sintering furnace according to an embodiment of 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 including a cooling device 5 according to the present invention includes a vacuum standby chamber 2, a preheating device 3 that performs dewaxing, a sintering device 4 that performs sintering, and a cooling device. 5 can be configured. The continuous sintering furnace 1 shown in FIG. 1 is configured such that an inlet door 11 for carrying in a workpiece before processing and an outlet door 12 for carrying out the workpiece after processing are driven up and down by opening and closing devices 13 and 14, respectively. ing. 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 transfer roller 21 for transferring the workpiece 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、ワーク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。本件発明に係る冷却装置５を備える連続焼結炉１は、このような搬送ローラ２１にワークＷを載置し、搬送ローラ２１の回転によってワーク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 transport rollers 21 are arranged at the same height and at an interval narrower than the transport direction length of the jig J on which the workpiece 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 provided with the cooling device 5 according to the present invention places the workpiece W on such a conveyance roller 21 and gradually moves the workpiece W forward by the rotation of the conveyance roller 21. A method of applying a cooling process is adopted.
　ここで、本件発明に係る冷却装置５について説明する前に、図１に示す連続焼結炉１においてワークＷに施される処理に関して簡単に説明しておく。まず、ワークＷは、連続焼結炉１の搬入用の入口扉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、搬入されたワーク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が蒸発除去される。そして、予備加熱装置３での処理が行われたワークＷは、焼結装置４内に搬入され、焼結温度である９５０～１１２０℃まで加熱され焼結処理される。焼結処理が終了した後のワークＷは、冷却装置５において冷却され、搬出用の出口扉１２から搬出される。 Here, before explaining the cooling device 5 according to the present invention, a brief description will be given of the treatment applied to the workpiece W in the continuous sintering furnace 1 shown in FIG. First, the workpiece W is carried into the continuous sintering furnace 1 through a carry-in entrance having the entrance door 11 for carrying in the continuous sintering furnace 1. Then, the loaded work W is carried into the preheating chamber 3 by the rotation of the carrying roller 21 serving as a carrying means, and is heated to, for example, 500 to 700 ° C. to evaporate and remove the previously added wax. Then, the workpiece W that has been processed in the preheating device 3 is carried into the sintering device 4 and heated to a sintering temperature of 950 to 1120 ° C. to be sintered. The workpiece W after the sintering process is finished is cooled by the cooling device 5 and carried out from the outlet door 12 for carrying out.
　なお、本件発明の連続焼結炉１に備わる予備加熱装置３、及び焼結装置４は、ワークＷに対して上下左右の四面に熱源（不図示）が設けられる。本件発明の連続焼結炉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ワークＷに伝えることが出来る。その結果、本件発明の連続焼結炉１によれば、治具Ｊ上に積載された全てのワークＷに対して均一に加熱処理を行うことが出来る。 The preheating device 3 and the sintering device 4 provided in the continuous sintering furnace 1 of the present invention are provided with heat sources (not shown) on the upper, lower, left and right surfaces of the workpiece W. The continuous sintering furnace 1 of the present invention employs a roller hearth type, so that the heat of the heat source disposed on the bottom surface between adjacent rollers can be directly transmitted to the workpiece W. As a result, according to the continuous sintering furnace 1 of the present invention, it is possible to uniformly heat all the workpieces W loaded on the jig J.
　次に、本件発明に係る冷却装置５に関して以下に説明していく。図２及び図３に示すように、本件発明に係る冷却装置５は、ワークＷを搬入する搬入扉５９と、ワークＷを搬出する図１に示す出口扉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ワークＷ全てに対して均一に冷却処理を行うことが出来る。ちなみに、本件発明に係る冷却装置５は、冷却処理室５２内を加圧する加圧装置（不図示）を介して接続し、冷却処理時において、冷却処理室５２内の圧力を１５００ＴＯＲＲ程度の所定の圧力まで加圧制御することが可能である。冷却時に冷却ガスを撹拌（循環）する場合には、冷却処理室５２内を加圧状態とすることによって、大気圧状態の場合に比べ、循環する冷却ガスの場所毎の冷却速度の差を低減させることが出来る。このような冷却処理室５２内の加圧による効果を利用することにより、冷却歪みが生じやすいワークＷであっても歪み発生を抑制することができ、高精度の寸法精度を維持したまま冷却処理を行うことが出来る。 Next, the cooling device 5 according to the present invention will be described below. As shown in FIGS. 2 and 3, the cooling device 5 according to the present invention has a configuration in which a loading door 59 for loading the workpiece W and an outlet door 12 illustrated in FIG. 1 for unloading the workpiece W are opened and closed. It has a structure that can close the inside of the cooling device 5 by closing the door. The cooling device 5 of the present invention can uniformly cool all the plurality of workpieces W loaded on the jig J by performing cooling in a state where the inside is pressurized. Incidentally, the cooling device 5 according to the present invention is connected via a pressurizing device (not shown) that pressurizes the inside of the cooling processing chamber 52, and during the cooling processing, the pressure in the cooling processing chamber 52 is a predetermined value of about 1500 TORR. It is possible to control the pressurization up to the pressure. When the cooling gas is agitated (circulated) during cooling, the cooling process chamber 52 is pressurized to reduce the difference in cooling rate at each location of the circulating cooling gas compared to the atmospheric pressure state. It can be made. By utilizing the effect of the pressurization in the cooling processing chamber 52, it is possible to suppress the occurrence of distortion even in the workpiece W where the cooling distortion is likely to occur, and the cooling process while maintaining high dimensional accuracy. Can be done.
　また、本件発明に係る冷却装置５は、治具Ｊに積載されたワーク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るため、冷却処理時の黒鉛板５１による断熱作用、及び放熱作用によってワークＷの治具Ｊ上の載置位置に影響されずに個体差無く各ワークを均一な速度で冷却することが出来る。また、本件発明に係る冷却装置１０は、その内部に黒鉛板５１が配置されることで、冷却処理室５２内に配置されるワークＷに直接的に冷却ガスが接触せず、当該ワークＷを急冷する場合であっても均一な速度で冷却することが可能になる。 Moreover, since the cooling device 5 according to the present invention has a structure in which the graphite plate 51 is provided so as to surround all the workpieces W loaded on the jig J, the heat insulating action by the graphite plate 51 during the cooling process, In addition, the work can be cooled at a uniform speed without any individual difference without being affected by the placement position of the work W on the jig J by the heat radiation action. Further, the cooling device 10 according to the present invention has the graphite plate 51 disposed therein, so that the cooling gas does not directly contact the workpiece W disposed in the cooling processing chamber 52, and the workpiece W Even in the case of rapid cooling, it is possible to cool at a uniform speed.
　本件発明に係る冷却装置５は、上述したように、治具Ｊに積載されたワークＷ全てを包囲するように黒鉛製の板５１を設けたものであり、この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、本件発明の冷却装置５内でワークＷを囲う黒鉛板５１は、蓄熱体としても作用し、ワーク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ワークＷからの熱放射を抑制することで、ワーク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、本件発明の冷却装置５によれば、冷却室５２内におけるワーク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、ワーク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 according to the present invention is provided with the graphite plate 51 so as to surround all the workpieces W loaded on the jig J, and a system for performing the cooling process in this state is provided. 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 workpiece W in the cooling device 5 of the present invention also acts as a heat storage body, can prevent partial overcooling of the workpiece W, and from the workpiece W by the temperature rise of the graphite plate itself. By suppressing the heat radiation, the temperature difference due to the arrangement position of the workpiece W can be reduced. As a result, according to the cooling device 5 of the present invention, it is possible to cool all the workpieces W in the cooling chamber 52 at a uniform speed, resulting in variations in mechanical characteristics in the portions of the workpieces W and products. There is no loss of 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、本件発明に係る冷却装置５は、その内部にファン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、本件発明に係る冷却装置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。従って、本件発明に係る冷却装置によれば、上述した冷却処理室５２内の圧力の状態とファン回転数の条件とを最適な組合せとすることで、ワークＷの冷却処理速度を向上させながらも、ワークＷに所望の機械的特性を安定して付与することが出来ることとなる。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, the cooling device 5 according to the present invention has a fan 53 provided therein and is rotated by a motor stored in the fan driving device M, thereby introducing a cooling gas (not shown). The cooling gas introduced from the mouth can be circulated in the cooling processing chamber 52. Further, in the cooling device 5 according to the present invention, the heat exchanger 55 that distributes the heat introduced from the refrigerant introduction pipe 56 and exchanges heat, and leads the heat through the refrigerant lead-out pipe 57 can be installed in the cooling processing chamber 52. . When the cooling device 5 of the present invention has such a structure, the cooling device or cooling air circulating in the cooling processing chamber 52 is cooled each time it contacts the heat exchanger 55 and can be rapidly cooled. 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. Therefore, according to the cooling device according to the present invention, the cooling process speed of the workpiece W can be improved by optimizing the combination of the pressure state in the cooling process chamber 52 and the fan rotation speed condition. The desired mechanical characteristics can be stably imparted to the workpiece W. 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.
　本件発明に係る冷却装置５は、以上のような構造を備えるので、優れた冷却歪み抑制効果と、冷却歪み発生可能性が低い温度領域での冷却効率向上効果の両方を得ることが出来る。なお、ワークＷの冷却処理が行われた後は、冷却装置５内に例えば窒素ガスを導入して、大気圧状態に復圧し、その後、搬出側の出口扉１２を開け、搬送ローラ２１を回転させることで、冷却装置５からワークＷを搬出することが出来る。 Since the cooling device 5 according to the present invention has the above-described structure, it is possible to obtain both an excellent cooling strain suppression effect and a cooling efficiency improvement effect in a temperature region where the possibility of occurrence of cooling strain is low. After the work W is cooled, for example, nitrogen gas is introduced into the cooling device 5 to restore the pressure to atmospheric pressure, and then the outlet door 12 on the carry-out side is opened and the transport roller 21 is rotated. By doing so, the workpiece W can be carried out from the cooling device 5.
　また、図３には、複数段に積み重なって載置されたワークＷが複数示されているが、本件発明の冷却装置５によれば、ワークＷの載置位置に関係なく均一に冷却させることが可能となり、ワークＷの均一な冷却を確実に行うことで、不良品発生を抑制することが出来る。 3 shows a plurality of workpieces W stacked and placed in a plurality of stages. According to the cooling device 5 of the present invention, the workpiece W can be uniformly cooled regardless of the placement position of the workpiece W. It becomes possible, and generation | occurrence | production of inferior goods can be suppressed by performing uniform cooling of the workpiece | work W reliably.
　また、本件発明に係る冷却装置５によれば、冷却処理時間を従来に比べて大幅に短縮することが可能であるため、連続式焼結炉１を構成する各装置の中でも比較的処理時間の短い予備加熱装置３や焼結装置４と並行して処理を行うことが可能となる。そのため、本件発明に係る冷却装置５を備えた連続式焼結炉１によれば、非常に効率よく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、本件発明に係る冷却装置を備えることで、各処理装置２～５を順次移動するように搬送ローラ２１によりワークＷを移動（図１に示す矢印方向）させる際に効率よくワークＷを移動させることが出来るようになる。 Further, according to the cooling device 5 according to the present invention, the cooling processing time can be significantly shortened as compared with the conventional case. Therefore, among the devices constituting the continuous sintering furnace 1, the processing time is relatively long. Processing can be performed in parallel with the short preheating device 3 and the sintering device 4. Therefore, according to the continuous sintering furnace 1 provided with the cooling device 5 according to the present invention, the processing can be performed very efficiently. In other words, the continuous sintering furnace 1 includes the cooling device according to the present invention, so that the workpiece W is moved by the transport roller 21 so as to sequentially move the processing devices 2 to 5 (in the direction of the arrow shown in FIG. 1). It is possible to move the workpiece W efficiently when making it.
　また、本件発明に係る冷却装置において、ワークは、内燃機関用カムシャフトであることが好ましい。 In the cooling device according to the present invention, the work is preferably a camshaft for an internal combustion engine.
　過酷な摺動条件下で使用される内燃機関用カムシャフトは、内燃機関の高性能化や高出力化に伴い、従来より高い耐摩耗性を備え、高面圧、高負荷に耐えられる軽量のカムシャフトが求められている。具体的には、内燃機関用カムシャフトには、エンジン高回転、高接触面圧下での厳しい摺動条件に耐えられる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ものが求められている。これらの要求に応えるために、内燃機関用カムシャフトは、焼結材のカムロブを鋼製シャフトに接合した所謂焼結カムシャフトが用いられ、焼結後の冷却処理において、カムシャフトの冷却速度を全周均一となるように制御することが求められている。 Camshafts for internal combustion engines that are used under severe sliding conditions have higher wear resistance than conventional models, and are light weight that can withstand high surface pressures and loads as the internal combustion engines become more powerful and have higher output. There is a need for a camshaft. Specifically, a camshaft for an internal combustion engine is required to have excellent wear characteristics such as pitting resistance and scuffing resistance that can withstand severe sliding conditions under high engine speed and high contact surface pressure. . In order to meet these requirements, a camshaft for an internal combustion engine is a so-called sintered camshaft in which a sintered cam lobe is joined to a steel shaft, and the cooling speed of the camshaft is increased in the cooling process after sintering. Control is required so that the entire circumference is uniform.
　ここで、本件発明に係る冷却装置５は、配置される黒鉛板がカムシャフトを包囲する構造を備えているため、当該カムシャフトをムラ無く均一な速度で冷却することが出来る。また、本件発明に係る冷却装置においては、冷却処理室５２内の圧力の状態とファン回転数の条件とを最適な組合せにより、カムシャフトに求められる上記各特性を短時間で安定して付与することが出来ることとなる。例えば、焼結カムシャフトの冷却処理においては、焼結処理が終了した後、まず冷却処理室５２内の圧力が７６０ｔｏｒｒでファン回転数が０Ｈｚ～２０Ｈｚの状態で所定時間冷却（第１徐冷モード）し、次に冷却処理室５２内の圧力が９１０ｔｏｒｒでファン回転数が２０Ｈｚ～３０Ｈｚの状態で所定時間冷却（第２徐冷モード）し、次に冷却処理室５２内の圧力が１５００ｔｏｒｒでファン回転数が３０Ｈｚ～６０Ｈｚの状態で所定時間冷却（急冷モード）するような冷却モード条件を設定することが出来る。このように、本件発明に係る冷却装置によれば、当該焼結カムシャフトの冷却速度をＡ１変態点付近の温度の前後で切り変えることも可能であり、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焼結カムシャフトを、短時間で安定して提供することが出来る。 Here, since the cooling device 5 according to the present invention has a structure in which the arranged graphite plate surrounds the camshaft, the camshaft can be cooled at a uniform speed without unevenness. Further, in the cooling device according to the present invention, the above-mentioned characteristics required for the camshaft are stably imparted in a short time by an optimal combination of the pressure state in the cooling processing chamber 52 and the fan rotational speed condition. It will be possible. For example, in the cooling process of the sintered camshaft, after the sintering process is completed, first, the cooling in the cooling process chamber 52 is performed at a pressure of 760 torr and the fan rotational speed is 0 Hz to 20 Hz for a predetermined time (first slow cooling mode). Next, cooling is performed for a predetermined time (second slow cooling mode) in a state where the pressure in the cooling processing chamber 52 is 910 torr and the fan rotational speed is 20 Hz to 30 Hz, and then the fan is heated in the cooling processing chamber 52 at 1500 torr. Cooling mode conditions can be set such that cooling is performed for a predetermined time (rapid cooling mode) at a rotational speed of 30 Hz to 60 Hz. Thus, according to the cooling device according to the present invention, a cooling rate of the sintered camshaft A 1 can also be varied cut before and after the temperature near the transformation point, pitting resistance and the scuffing resistance, etc. A sintered camshaft excellent in wear characteristics can be provided stably in a short time.
　参考までに、焼結カムシャフトの加熱処理及び冷却処理は、処理効率の向上を図るため、例えばカムシャフト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される（図３におけるワークＷ参照のこと。）。従って、カムシャフトは載置される位置によって温度差が生じやすく、加熱処理や冷却処理の際に、カムシャフトの全周を均一に加熱・冷却することが必要とされる。本件発明の連続焼結炉１によれば、上述したように、ローラハース式を採用することで、加熱処理においては底面側にも熱源を配置出来、冷却処理においても底面側に黒鉛板を配置出来るため、カムシャフトの温度を個体差なく制御することが可能となる。 For reference, the heat treatment and cooling treatment of the sintered camshaft is performed at once in a state where, for example, a plurality of placement plates stacked in a horizontal and horizontal manner are stacked in order to improve the processing efficiency. (See Work W in FIG. 3). Therefore, the temperature difference between the camshafts is likely to occur depending on the position where the camshaft is placed, and it is necessary to uniformly heat and cool the entire circumference of the camshaft during the heat treatment and the cooling treatment. According to the continuous sintering furnace 1 of the present invention, as described above, a heat source can be arranged on the bottom surface side in the heat treatment, and a graphite plate can be arranged on the bottom surface side in the cooling treatment as well. Therefore, the temperature of the camshaft can be controlled without individual differences.
　本件発明に係る冷却装置は、複数のワーク全てを包囲して黒鉛板を配置した構成とすることで、全てのワークを短時間でムラ無く均一な速度で冷却することが出来る。そのため、本件発明に係る冷却装置によれば、ワークの品質向上と、処理時間の短縮とを実現することが出来、製造コストの低減化を図ることが出来る。以上のことから、本件発明に係る冷却装置によれば、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使用することが出来る。 The cooling device according to the present invention has a configuration in which a plurality of workpieces are surrounded and a graphite plate is disposed, so that all the workpieces can be cooled in a short time and at a uniform speed. Therefore, according to the cooling device according to the present invention, it is possible to improve the quality of the workpiece and shorten the processing time, and to reduce the manufacturing cost. From the above, the cooling device according to the present invention can be suitably used for other sliding elements used in, for example, an internal combustion engine, which require high quality and high mechanical strength.
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　　ワーク（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 Work (camshaft)

Claims (2)

  1. 　複数段に段積みされた載置用治具に積載した複数のワークを、複数の並設されたローラーにより搬送して加熱処理と冷却処理と順次行うローラハース式連続炉に備わる冷却装置において、
    　当該冷却装置は、加熱処理を施した複数のワークを収容した状態で密閉可能な冷却装置と、
    　当該冷却装置を減圧する減圧装置と、
    　当該冷却装置内において冷却ガスを循環させると共に、その循環速度を調節可能な冷却ファンと、
    　当該冷却ガスを冷却するための熱交換器と、
    　当該冷却装置の内部に当該複数のワークを包囲するように配した黒鉛板を備えることを特徴とする冷却装置。     In a cooling device provided in a roller hearth type continuous furnace in which a plurality of workpieces loaded on a mounting jig stacked in a plurality of stages are conveyed by a plurality of rollers arranged in parallel and sequentially subjected to a heating process and a cooling process,
    The cooling device is a cooling device that can be sealed in a state in which a plurality of heat-treated workpieces are accommodated, and
    A decompression device for decompressing the cooling device;
    A cooling fan that circulates the cooling gas in the cooling device and adjusts the circulation speed;
    A heat exchanger for cooling the cooling gas;
    A cooling device comprising a graphite plate disposed so as to surround the plurality of workpieces inside the cooling device.
  2. 　前記ワークは、内燃機関用カムシャフトである請求項１に記載の冷却装置。 The cooling device according to claim 1, wherein the workpiece is a camshaft for an internal combustion engine.
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