WO2019181454A1 - Procédé de production de corps fritté - Google Patents

Procédé de production de corps fritté Download PDF

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Publication number
WO2019181454A1
WO2019181454A1 PCT/JP2019/008337 JP2019008337W WO2019181454A1 WO 2019181454 A1 WO2019181454 A1 WO 2019181454A1 JP 2019008337 W JP2019008337 W JP 2019008337W WO 2019181454 A1 WO2019181454 A1 WO 2019181454A1
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WO
WIPO (PCT)
Prior art keywords
raw material
sintered
material powder
sintered body
gear
Prior art date
Application number
PCT/JP2019/008337
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English (en)
Japanese (ja)
Inventor
剛志 門村
中西　徹
Original Assignee
日本電産株式会社
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Filing date
Publication date
Application filed by 日本電産株式会社 filed Critical 日本電産株式会社
Publication of WO2019181454A1 publication Critical patent/WO2019181454A1/fr

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    • 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
    • B22F3/02—Compacting only
    • B22F3/093—Compacting only using vibrations or friction
    • 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
    • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
    • B22F5/08—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product of toothed articles, e.g. gear wheels; of cam discs
    • 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
    • F16H—GEARING
    • F16H55/00—Elements with teeth or friction surfaces for conveying motion; Worms, pulleys or sheaves for gearing mechanisms
    • F16H55/02—Toothed members; Worms
    • F16H55/06—Use of materials; Use of treatments of toothed members or worms to affect their intrinsic material properties

Definitions

  • the present invention relates to a method for producing a sintered body.
  • a sintered gear sintered body
  • compression-molding compacting raw material powder
  • the sintered gear manufactured by this method has a dimensional error of about 0.03 mm with respect to the sintered gear to be manufactured.
  • a high-precision sintered gear used for a robot hand or the like needs to be finished to a dimensional error (about 0.01 mm) comparable to cutting.
  • An object of the present invention is to provide a method for manufacturing a sintered body capable of manufacturing a sintered gear with high dimensional accuracy without using dedicated equipment and without performing secondary processing (post-processing).
  • the exemplary invention of the present application includes a step of compressing a raw material powder containing raw material particles with a molding die to obtain a molded body, and a step of firing the molded body to obtain a sintered body.
  • a method for producing a sintered body characterized by applying vibration and impact force in the vertical direction to the raw material powder in the mold.
  • a sintered body with high dimensional accuracy can be manufactured.
  • FIG. 1 is a plan view (a) and a cross-sectional view (b) schematically showing a configuration (sintered gear) of a sintered body according to an embodiment of the present invention
  • FIG. It is a figure which shows schematic structure of the shaping
  • a sintered gear 1 shown in FIG. 1 includes a disc-shaped gear body 2 and a plurality of teeth 3 that are arranged along the circumferential direction of the gear body 2 and project radially outward. The plurality of teeth 3 are provided at substantially equal intervals.
  • the sintered gear 1 is composed of a sintered body of raw material powder.
  • the configuration of the raw material powder will be described in detail later.
  • the size of the sintered gear 1 is not particularly limited because it is designed according to the application to be used, but when the sintered gear 1 is a gear for a robot hand (high-precision gear), for example, the following Designed as such.
  • the tip circle diameter (indicated by “D” in FIG. 1) of the sintered gear 1 is preferably about 3 to 15 mm, more preferably about 5 to 10 mm.
  • the number of teeth of the sintered gear 1 is preferably about 15 to 40, more preferably about 20 to 35.
  • the module indicating the size (tooth thickness) of the teeth 12 is preferably about 0.15 to 0.3 mm, and more preferably about 0.15 to 0.25 mm. Even such a small (high accuracy) sintered gear 1 can be manufactured with high dimensional accuracy by using the raw material powder of the present invention.
  • the tooth width of the tooth 12 (indicated by “W” in FIG. 1) is preferably about 1 to 10 mm, and more preferably about 2 to 5 mm.
  • a sintered gear 1 is a so-called spur gear, the present invention is not limited to this, and may be, for example, a screw gear, a bevel gear, a worm gear, a hypoid gear, or the like.
  • a sintered gear 1 is manufactured as follows. Hereinafter, a method for manufacturing the sintered gear 1 (a method for manufacturing a sintered gear) will be described.
  • the method for manufacturing a sintered gear according to the present embodiment includes: [1] a molding step of compression molding raw material powder to obtain a molded body having a shape corresponding to the sintered gear 1, and [2] firing the molded body. And a firing step for obtaining a sintered body, and [3] a surface treatment step for heat-treating the sintered body to form an oxide film covering the surface thereof.
  • a molding step of compression molding raw material powder to obtain a molded body having a shape corresponding to the sintered gear 1
  • a firing step for obtaining a sintered body and [3] a surface treatment step for heat-treating the sintered body to form an oxide film covering the surface thereof.
  • molding apparatus 10 shown in FIG. 2 is provided with the shaping
  • the molding die 20 includes a die 21 having a through hole 211 that penetrates in the thickness direction, and an upper punch 22 and a lower punch 23 that are inserted into the through hole 211 of the die 21.
  • the shape of the inner peripheral surface of the die 21 that defines the through-hole 211 corresponds to the shape (uneven shape) of the outer peripheral surface of the sintered gear 1 to be manufactured.
  • a core pin 231 extending along the axial direction A vibrating body 232 that applies vibration to the core pin 231 is disposed inside the lower punch 23, inside the lower punch 23, a core pin 231 extending along the axial direction.
  • a vibrating body 232 that applies vibration to the core pin 231 is disposed inside the lower punch 23, inside the lower punch 23, a core pin 231 extending along the axial direction.
  • the molding apparatus 10 has a mechanism for lifting the die 21 and the lower punch 23 vertically upward and then dropping them. With this configuration, it is possible to impart vibration and a vertical impact force to the raw material powder in the mold 20.
  • a molded body is formed according to the following steps.
  • the feeder 30 is slid on the die 21 so as to cover the cavity 212 with the feeder 30, and the raw material powder is filled into the cavity 212 from the feeder 30 (see FIG. 2B).
  • the raw material powder used to manufacture the sintered gear 1 is preferably configured as follows.
  • the raw material powder includes raw material particles having a particle size of a module [mm] or less of the sintered gear 1.
  • the raw material particles can be filled not only into the tooth root portion of the cavity 212 but also into the tooth tip portion as necessary and sufficient.
  • the particle size of the raw material particles is adjusted so that B / A is 10 or less. Has been. That is, it is adjusted so that the difference in particle size of the raw material particles contained in the raw material powder does not become large.
  • B / A is preferably 7 or less, more preferably about 2 to 4.
  • the maximum particle size B of the raw material particles is preferably not more than half that of the module of the sintered gear 1, and more preferably about 0.35 to 0.45 times the module.
  • the specific value of the maximum particle size B of the raw material particles is preferably about 0.1 to 0.25 mm. More preferably, it is about 0.2 mm.
  • the specific value of the minimum particle diameter A of the raw material particles is preferably about 0.02 to 0.05 mm, and more preferably about 0.025 to 0.04 mm.
  • the raw material particles can be produced using, for example, an atomizing method such as a pulverizing method, a water atomizing method, a gas atomizing method, a reduction method, a carbonyl method, or the like.
  • an atomizing method such as a pulverizing method, a water atomizing method, a gas atomizing method, a reduction method, a carbonyl method, or the like.
  • the constituent material of the raw material particles include Fe (iron) alone, various metal materials such as an alloy containing Fe as a main component and an arbitrary element, and various ceramic materials such as apatite-based ceramics.
  • elements added to the alloy include Cr (chromium), Mo (molybdenum), Mn (manganese), Ni (nickel), Cu (copper), W (tungsten), V (vanadium), and Co ( Cobalt), Si (silicon), C (carbon), and the like.
  • Such raw material powder may contain a lubricant.
  • liquidity of raw material powder can be improved more.
  • the lubricant include fatty acids such as stearic acid, metal salts thereof, derivatives thereof (eg, amides, esters, etc.), fluorine resins, and the like. These compounds can be used individually by 1 type or in combination of 2 or more types.
  • the amount of lubricant contained in the raw material powder is not particularly limited, but is preferably 5% by mass or less, more preferably about 0.1 to 3% by mass.
  • the fluidity of the raw material powder can be adjusted to a sufficiently high value by containing a small amount (about 0.1 to 0.5% by mass) of a lubricant.
  • the specific fluidity of the raw material powder is preferably about 25 to 50 sec / 50 g, more preferably about 30 to 40 sec / 50 g.
  • a raw material powder having such a fluidity can be supplied to the cavity 212 with high stability.
  • the fluidity can be measured in accordance with a metal powder-fluidity measurement method defined in JIS Z 2502 (2012).
  • Second step (overfill step) Next, the die 21 and the lower punch 23 are relatively approached to reduce the volume of the cavity 212 (space 211), and a part of the raw material powder is returned to the feeder 30. Thereby, the packing density of raw material powder can be raised more.
  • Third Step Thereafter, the feeder 30 is slid on the die 21 to be retracted from the cavity 212. At this time, surplus raw material powder is scraped off.
  • the vibrating body 232 is operated to vibrate the core pin 231. Accordingly, vibration is applied to the raw material powder in the cavity 212 through the lower punch 23. At this time, the raw material particles in the cavity 212 are rearranged, and the packing density of the raw material powder can be increased.
  • the time for applying vibration is preferably about 0.1 to 5 seconds, more preferably about 0.5 to 3 seconds. By applying vibration to the raw material powder in a relatively short time, the packing density can be further increased while preventing the raw material powder from scattering.
  • the frequency of vibration is not particularly limited, and is appropriately set according to the particle size of the raw material particles, the fluidity of the raw material powder, and the like in order to increase the packing density of the raw material powder into the cavity 212.
  • the die 21 and the lower punch 23 are lifted vertically upward and then dropped.
  • this operation is also referred to as “tap”.
  • an impact force in the vertical direction can be applied to the raw material powder in the cavity 212.
  • the number of times of applying the impact force is preferably about 1 to 5 times, and more preferably about 2 to 3 times.
  • the density of the raw material powder can be further increased without disturbing the arrangement of the raw material particles rearranged in the cavity 212.
  • the height at which the die 21 and the lower punch 23 are lifted is not particularly limited, but is preferably about 1 to 10 mm, and more preferably about 3 to 7 mm. Thereby, an appropriate impact force can be imparted to the raw material powder.
  • the tip of the upper punch 22 is inserted into the cavity 212, and the raw material powder is compressed by the lower punch 23 and the upper punch 22 (see FIG. 3C).
  • the pressure at which the raw material powder is compressed is not particularly limited, but is preferably about 0.5 to 3 tons, and more preferably about 1 to 2 tons.
  • the molded body 11 having a shape corresponding to the sintered gear is obtained in the cavity 212.
  • the die 21 and the lower punch 23 are brought relatively close to each other, and the molded body 11 is discharged from the cavity 212.
  • the obtained molded body 11 is fired to obtain a sintered body.
  • diffusion occurs at the interface between the raw material particles, leading to sintering.
  • the molded body 11 is entirely contracted to obtain a high-density sintered body.
  • the firing temperature is not particularly limited because it is set depending on the composition, particle size, and the like of the raw material powder used in the production of the molded body 11, but is preferably about 950 to 1300 ° C., and preferably about 1000 to 1200 ° C. Is more preferable.
  • the firing time is preferably about 0.2 to 3 hours, and more preferably about 0.5 to 2 hours.
  • the atmosphere during firing is not particularly limited, and examples thereof include an air atmosphere, an oxidizing atmosphere, a reducing atmosphere, an inert gas atmosphere, or a reduced-pressure atmosphere obtained by reducing these atmospheres. Since the sintered body obtained in this way has extremely high dimensional accuracy, the sintered gear 1 can be formed without performing secondary processing such as forging and cutting.
  • the secondary processing refers to processing that mechanically changes the shape of the sintered body, and the secondary processing does not include surface treatment (heating treatment) described later.
  • the error between the dimension in the radial direction of the sintered gear 1 to be manufactured and the dimension in the radial direction of the obtained sintered body is 6 ⁇ , preferably 0.02 mm or less, more preferably 0.005 to 0. About .015 mm.
  • the surface treatment step Next, the sintered body is subjected to a surface treatment for forming an oxide film on the surface.
  • a surface treatment for forming an oxide film on the surface.
  • the surface treatment temperature is not particularly limited, but is preferably about 500 to 1000 ° C, more preferably about 700 to 950 ° C.
  • the surface treatment time is preferably about 0.5 minute to 1 hour, more preferably about 1 to 45 minutes.
  • the atmosphere for the surface treatment is not particularly limited, and examples thereof include a steam atmosphere, an oxidizing atmosphere, an inert gas atmosphere, or a reduced pressure atmosphere obtained by reducing these atmospheres. [3] The surface treatment step may be performed as necessary and may be omitted.
  • the manufacturing method of the sintered compact of this invention was demonstrated based on suitable embodiment, this invention is not limited to these.
  • the sintered gear 1 is not only an industrial machine part such as a robot hand, but also, for example, an automobile part, a bicycle part, a railway vehicle part, a marine part, an aircraft part, a space transportation part, etc. It is used for parts for electronic equipment such as parts for transportation equipment, parts for personal computers and parts for portable terminals, parts for electric equipment such as refrigerators, washing machines and air conditioners, parts for plants, parts for watches, and the like.
  • the sintered body is not limited to the sintered gear 1 and may be, for example, a bearing, a cylinder, or the like.
  • Example 1 [A] First, raw material particles containing Fe as a main component (maximum particle size B: 0.212 mm, manufactured by Höganäs) were prepared. [B] Next, particles having a particle diameter of less than 0.032 mm were removed from the raw material particles using a sieve. Therefore, B / A is 6.6.
  • this raw material powder was compression molded using a molding apparatus shown in FIG. 2 to obtain a molded body.
  • the raw material powder was filled into the cavity from the feeder. After applying vibration to the raw material powder in the cavity for 1 second, an impact force was applied by two tapping operations. Thereafter, the raw material powder was scraped off by a feeder and then compressed with an upper punch and a lower punch. The pressure during compression molding was 1.1 ton and the temperature was room temperature.
  • the obtained molded body was fired at 1200 ° C. for 1 hour in an air atmosphere to obtain a sintered gear (sintered body).
  • the shape of the sintered gear was a tip diameter 9 mm, a module 0.3 mm, and 27 teeth.
  • the obtained sintered gear was heat-treated at 750 ° C. for 1 minute in an air atmosphere to form an oxide film having an average thickness of 0.01 mm on the surface of the sintered gear. As a result, a sintered gear with an oxide film was obtained. The average thickness of the oxide film was measured by a cross-sectional observation method.
  • Example 2 A sintered gear with an oxide film was obtained in the same manner as in Example 1 except that an overfill operation was performed before applying vibration to the raw material powder.
  • Example 3 A sintered gear with an oxide film was obtained in the same manner as in Example 1 except that the time for applying vibration and the number of taps were changed.
  • Example 4 A sintered gear with an oxide film was obtained in the same manner as in Example 1 except that the shape of the sintered gear was 6 mm in tip diameter, 0.2 mm in module, and 28 teeth.
  • Example 1 A sintered gear with an oxide film was obtained in the same manner as in Example 1 except that the application of vibration to the raw material powder in the cavity was omitted.
  • Comparative Example 2 A sintered gear with an oxide film was obtained in the same manner as in Example 1 except that the application of the impact force by the tap operation to the raw material powder in the cavity was omitted.
  • the dimensional error 6 ⁇ in the thickness direction of the molded body can be reduced, that is, the density of the molded body can be increased.
  • the sintered gear of each example obtained by firing such a molded body had high dimensional accuracy. Moreover, the said effect showed the tendency to improve by adding overfill operation. On the other hand, if the application of vibration or impact force to the raw material powder in the cavity is omitted, the density of the molded body could not be increased.
  • the sintered gear of each comparative example obtained by firing such a molded body was inferior in dimensional accuracy.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Thermal Sciences (AREA)
  • Powder Metallurgy (AREA)
  • Gears, Cams (AREA)

Abstract

Le problème décrit par la présente invention est de fournir un procédé de production de corps fritté avec lequel il est possible de produire un engrenage fritté avec une précision dimensionnelle élevée sans utiliser d'équipement dédié et sans effectuer de traitement secondaire (post-traitement). La solution selon l'invention porte sur un procédé de production de corps fritté qui comprend une étape de moulage par compression d'une poudre de matière première contenant des particules de matière première avec un moule pour obtenir un corps moulé et une étape de frittage du corps moulé pour obtenir un corps fritté. Dans l'étape d'obtention du corps moulé, une vibration et une force d'impact dans la direction verticale sont appliquées aux particules de matière première à l'intérieur du moule. En outre, il est préférable d'appliquer la vibration pendant une durée de 0,1 à 5 secondes et d'appliquer la force d'impact 1 à 5 fois.
PCT/JP2019/008337 2018-03-22 2019-03-04 Procédé de production de corps fritté WO2019181454A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2018-054553 2018-03-22
JP2018054553A JP2019167566A (ja) 2018-03-22 2018-03-22 焼結体の製造方法

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WO2019181454A1 true WO2019181454A1 (fr) 2019-09-26

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002137039A (ja) * 2000-10-30 2002-05-14 Unisia Jecs Corp 焼結部材の鍛造方法
WO2002060677A1 (fr) * 2001-01-29 2002-08-08 Sumitomo Special Metals Co., Ltd. Procede de moulage de poudre

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002137039A (ja) * 2000-10-30 2002-05-14 Unisia Jecs Corp 焼結部材の鍛造方法
WO2002060677A1 (fr) * 2001-01-29 2002-08-08 Sumitomo Special Metals Co., Ltd. Procede de moulage de poudre

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