JP2016141847A - Warm sizing equipment and warm sizing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a warm sizing equipment capable of stably producing a sintered body having high accuracy and high level of hardness.SOLUTION: There is provided a warm sizing equipment comprising: a heating furnace for heating a ferrous sintered body to a temperature higher than Ae1 point to austenitize the ferrous sintered body; a quenching apparatus for quenching the sintered body from a temperature higher than the Ae1 point to a temperature which is lower than the Ae1 point and higher than the Ms point at a cooling rate at which pearlite does not precipitate; a press machine for achieving simultaneously a size correction of the sintered body and martensitic transformation of the sintered body by compressing the sintered body having a temperature higher than the Ms point with a mold having a temperature lower than the Ms point; a stacking apparatus for stacking sintered bodies discharged from the press machine on a stacking part having a temperature of room temperature in a sequential order; and a cooling conveying device for conveying the sintered body to the stacking part while blowing a cooling gas, whose temperature is room temperature or lower than room temperature, to the sintered bodies discharged from the press machine.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a warm sizing facility and a warm sizing method for producing a sintered body with high accuracy and high hardness.

  A powder metallurgy method is known as a method for obtaining a product having a final shape or a shape close thereto without performing cutting. The powder metallurgy method is generally a method in which an iron-based sintered material is obtained by forming a powder compact by compressing an iron-based powder material with a mold and then heating the powder compact. According to this method, since the product shape is molded by the mold, a product having a complicated shape can be mass-produced economically.

  In addition, in order to obtain a sintered body having high dimensional accuracy, a technique (so-called sizing) is known in which the sintered body obtained as described above is recompressed with a mold to correct the dimension. When this sizing is performed, it is possible to eliminate the influence of dimensional reduction caused by heating when sintering the green compact, and to obtain a sintered body having high dimensional accuracy.

  Moreover, in order to raise the hardness of a sintered compact, the method of giving heat processing, such as hardening and tempering, to a sintered compact is known.

  By the way, as a method for obtaining a sintered body with high accuracy and high hardness, a method of sizing the sintered body and then heat-treating the sintered body is conceivable. However, if it does in this way, the residual stress which arises inside a sintered compact at the time of sizing will be released by subsequent heat processing, and the dimensional accuracy of a sintered compact will fall. Therefore, in order to obtain high dimensional accuracy, there has been a problem that the sintered product after sizing and heat treatment has to be cut.

  In order to solve this problem, the applicant of the present application has proposed a technique described in Patent Document 1 (so-called warm sizing). This warm sizing is performed after an iron-based sintered body having a martensite transformation start temperature (Ms point) in a temperature range of 50 to 350 ° C. is heated to a temperature higher than the austenitizing temperature (Ael point) to be austenitized. The sintered body is rapidly cooled to a temperature lower than the Ae1 point and higher than the Ms point, taken out, and the sintered body is compressed with a mold. This is a method of simultaneously performing martensitic transformation of the aggregate.

Japanese Patent No. 3517916

  By the way, when the inventors of the present application manufactured a large number of sintered bodies by the above-described warm sizing, the dimensions of the obtained sintered bodies were obtained even though the conditions such as the temperature and pressure of the mold were the same. It was found that there was a very small variation (variation of about plus or minus 10 μm).

  The inventors investigated the cause of the dimensional variation of the sintered body. When the sintered bodies discharged from the warm sizing press apparatus were stacked in a stacking apparatus, the sintered body was the lowest. It has been found that the cooling rate varies depending on whether it is located at the position of the second stage or more from the bottom, which causes variations in the size of the sintered body.

  That is, when the sintered body is discharged from the warm sizing press apparatus, the temperature of the sintered body is higher than room temperature (for example, about 90 ° C.). On the other hand, in the stacking device for stacking the sintered bodies discharged from the press device, the stacking unit is stacked again from the first stage by shifting the position every time a predetermined number of stages (for example, seven stages) are stacked. The stacked body is stacked on the stacking portion, and the temperature of the stacking portion is room temperature.

  Here, among the sintered bodies stacked in the stacking portion, the sintered body at the lowest position is in direct contact with the normal temperature stacking portion, so that it is relatively comparatively discharged from the warm sizing press device. It will be rapidly cooled to room temperature.

  On the other hand, among the sintered bodies stacked in the stacking portion, the sintered bodies at the second and higher levels from the bottom are on the sintered body below, and thus do not directly contact the stacking portion. Therefore, it is cooled to room temperature relatively slowly after being discharged from the warm sizing press.

  In this way, when the sintered bodies discharged from the warm sizing press apparatus are sequentially stacked on the stacking part, the sintered body at the lowest position and the sintered bodies at the second and higher levels from the bottom are used. The cooling rate differs to that at room temperature. And it turned out that the dispersion | variation in the dimension of a sintered compact has arisen by the difference in the cooling rate in this stacking part.

  An object of this invention is to provide the warm sizing equipment which can manufacture a highly accurate and highly hard sintered body stably.

The warm sizing equipment according to one aspect of the present invention is
A heating furnace for heating the iron-based sintered body to a temperature higher than the austenitizing temperature (Ae1 point) to austenite;
The sintered body is received from the heating furnace, and the sintered body is rapidly cooled at a cooling rate at which pearlite does not precipitate from a temperature higher than the Ae1 point to a temperature lower than the Ae1 point and higher than the martensite transformation start temperature (Ms point). A quenching device,
The sintered body is received from the rapid cooling apparatus, and the sintered body having a temperature higher than the Ms point is compressed by a mold having a temperature lower than the Ms point, thereby correcting the size of the sintered body and martensitic transformation of the sintered body. A press device that simultaneously performs
A stacking device for sequentially stacking the sintered bodies discharged from the pressing device in a normal temperature stacking unit;
The stacking unit is disposed on the downstream side of the pressing apparatus and the upstream side of the stacking unit, and the sintered body is sprayed to the sintered body discharged from the pressing apparatus at a room temperature or lower temperature while blowing a cooling gas. A cooling and conveying device that conveys toward the
Is a warm sizing facility.

  Based on the above, it is possible to stably produce a sintered body with high accuracy and high hardness.

It is a figure which shows an example of the sintered compact which performs warm sizing with the warm sizing installation and warm sizing method concerning embodiment of this invention. It is sectional drawing along the II-II line of FIG. It is a figure which shows the other example of the sintered compact which performs warm sizing with the warm sizing installation and warm sizing method concerning embodiment of this invention. FIG. 4 is a sectional view taken along line IV-IV in FIG. 3. The inner rotor manufactured by the warm sizing facility and the warm sizing method according to the embodiment of the present invention, and the outer rotor manufactured by the warm sizing facility and the warm sizing method according to the embodiment of the present invention. It is a figure which shows the state which assembled the pump. It is a top view which shows the warm sizing installation concerning embodiment of this invention. FIG. 7 is an enlarged plan view of the cooling and conveying device and the stacking device shown in FIG. 6. It is sectional drawing which looked at the cooling conveyance apparatus and stacking apparatus shown in FIG. 7 from the front. When the inner rotor (sintered body) conveyed while blowing cold air with the cooling and conveying apparatus shown in FIG. 6 is stacked on the stacking portion, the outer teeth and outer outer teeth of the inner rotor of the uppermost, middle and lowermost inner rotors It is a graph which shows the result of having measured the magnitude | size (unit micrometer) of the tip clearance formed between the internal teeth of a rotor. When the inner rotor (sintered body) transported as it is without blowing cold air in the cooling transport device shown in FIG. 6 is stacked on the stacking portion, the inner rotor of the uppermost, middle and lowermost It is a graph which shows the result of having measured the magnitude | size (unit micrometer) of the chip clearance formed between an outer tooth and the inner tooth of an outer rotor.

[Description of Embodiment of the Present Invention]
(1) A warm sizing facility according to an aspect of the present invention is as follows:
A heating furnace for heating the iron-based sintered body to a temperature higher than the austenitizing temperature (Ae1 point) to austenite;
The sintered body is received from the heating furnace, and the sintered body is rapidly cooled at a cooling rate at which pearlite does not precipitate from a temperature higher than the Ae1 point to a temperature lower than the Ae1 point and higher than the martensite transformation start temperature (Ms point). A quenching device,
The sintered body is received from the rapid cooling apparatus, and the sintered body having a temperature higher than the Ms point is compressed by a mold having a temperature lower than the Ms point, thereby correcting the size of the sintered body and martensitic transformation of the sintered body. A press device that simultaneously performs
A stacking device for sequentially stacking the sintered bodies discharged from the pressing device in a normal temperature stacking unit;
The stacking unit is disposed on the downstream side of the pressing apparatus and the upstream side of the stacking unit, and the sintered body is sprayed to the sintered body discharged from the pressing apparatus at a room temperature or lower temperature while blowing a cooling gas. A cooling and conveying device that conveys toward the
Is a warm sizing facility.
By doing so, since the sintered body is cooled by the cooling and conveying device between the time when the sintered body is discharged from the press device and the time it reaches the stacking unit, the sintered body when it reaches the stacking unit is cooled. The temperature is sufficiently low. Therefore, when the sintered bodies are stacked in order on the stacking portion, the size of the sintered body varies between the sintered body at the lowest position and the sintered body at the second or higher level from the bottom. Is unlikely to occur. Therefore, it is possible to stably manufacture a sintered body with high accuracy and high hardness.
(2) The following configuration can be adopted as the cooling and conveying device.
A conveyor for conveying the sintered body toward the stacking unit;
A conveyor cover provided to cover the conveying path of the sintered body by the conveyor;
A cooling gas supply device for feeding the cooling gas into the conveyor cover.
(3) Moreover, the thing of the following structures is provided as a warm sizing method which concerns on 1 aspect of this invention.
An austenitizing step of heating the iron-based sintered body to a temperature higher than the austenitizing temperature (Ae1 point) to austenite;
After the austenitizing step, the sintered body is rapidly cooled at a cooling rate at which pearlite does not precipitate from a temperature higher than the Ae1 point to a temperature lower than the Ae1 point and higher than the martensitic transformation start temperature (Ms point). When,
After the rapid cooling step, the sintered body having a temperature higher than the Ms point is compressed with a mold having a temperature lower than the Ms point, so that the dimension correction of the sintered body and the martensitic transformation of the sintered body are simultaneously performed. A warm sizing process;
After the warm sizing step, a stacking step of sequentially stacking the sintered bodies on a normal temperature stacking portion;
After the warm sizing process and before the stacking process, the sintered compact is transported toward the stacking section while blowing a cooling gas at normal temperature or lower temperature to the sintered compact discharged from the press device. Cooling and transporting process,
A warm sizing method.

[Details of the embodiment of the present invention]
Specific examples of the warm sizing facility and the warm sizing method according to the embodiment of the present invention will be described below with reference to the drawings. In addition, this invention is not limited to these illustrations, is shown by the claim, and intends that all the changes within the meaning and range equivalent to a claim are included.

  1 and 2 show a sintered body 1 that performs warm sizing with a warm sizing facility and a warm sizing method according to an embodiment of the present invention. The sintered body 1 is an iron-based sintered body obtained by forming a powder-shaped body by compressing an iron-based powder material with a mold and then heating the powder-shaped body. As a powder material constituting the powder compact, 3.5 to 4.5 mass% nickel, 1.2 to 1.8 mass% copper, 0.3 to 0.7 mass% molybdenum, A composition containing 0.5 to 0.9% by mass of carbon and the remaining iron can be used.

  The sintered body 1 has an austenitizing temperature (Ae1 point) in a temperature range of 720 to 780 ° C, and martensitic transformation in a temperature range of 50 to 350 ° C (for example, 150 to 200 ° C) lower than the Ae1 point. It has a starting temperature (Ms point).

  The sintered body 1 has a flat shape with a thickness smaller than the outer diameter. When the sintered body 1 is subjected to warm sizing described later, the inner rotor 2 of the internal gear pump shown in FIG. 5 can be obtained as a highly accurate and hard sintered body. Further, instead of the sintered body 1 shown in FIGS. 1 and 2, warm sizing may be performed on the sintered body 1 shown in FIGS. When warm sizing is performed on the sintered body 1 shown in FIGS. 3 and 4, the outer rotor 3 of the internal gear pump shown in FIG. 5 can be obtained as a highly accurate and high hardness sintered body.

  The internal gear pump shown in FIG. 5 includes an annular outer rotor 3 and an inner rotor 2 disposed inside the outer rotor 3. On the inner periphery of the outer rotor 3, internal teeth 4 projecting radially inward are formed at equal pitches in the circumferential direction. On the outer periphery of the inner rotor 2, external teeth 5 projecting radially outward are formed at equal pitches in the circumferential direction. The number of teeth of the inner teeth 4 of the outer rotor 3 is one more than the number of teeth of the outer teeth 5 of the inner rotor 2. Both side surfaces 6 in the axial direction of the inner rotor 2 are flat surfaces. Both side surfaces 7 in the axial direction of the outer rotor 3 are also flat surfaces.

  The inner rotor 2 and the outer rotor 3 are extremely small so that the tip clearance t formed between the outer teeth 5 of the inner rotor 2 and the inner teeth 4 of the outer rotor 3 is several tens of μm (for example, about 20 to 30 μm). High dimensional accuracy is required. Further, since the axial side surface 6 of the inner rotor 2 and the axial side surface 7 of the outer rotor 3 are slidably supported, the inner rotor 2 and the outer rotor 3 are required to have extremely high wear resistance.

  FIG. 6 shows a warm sizing facility according to an embodiment of the present invention. This warm sizing facility includes a heating furnace 10, a quenching device 11, an intermediate transfer device 12, a press device 13, a cooling transfer device 14, and a stacking device 15 in order from the upstream side to the downstream side.

  The heating furnace 10 includes a heating chamber 16 held at a temperature higher than the Ae1 point of the sintered body 1 (for example, a temperature in the range of 800 to 900 ° C.), and a metal made so as to penetrate the heating chamber 16. Mesh belt conveyor 17. The mesh belt conveyor 17 conveys the sintered body 1 sequentially supplied from the upstream side from the inlet 16 a of the heating chamber 16 to the outlet 16 b of the heating chamber 16 through the inside of the heating chamber 16. The mesh belt conveyor 17 is driven by pitch feed that alternately moves and stops the sintered body 1.

  The quenching device 11 includes an oil tank 18, an input device 19 that inputs the sintered body 1 from the heating furnace 10 to the oil tank 18, and a take-out device 20 that takes out the sintered body 1 from the oil tank 18. Oil for cooling the sintered body 1 is stored in the oil tank 18. The temperature of the oil in the oil tank 18 is maintained at a temperature lower than the Ae1 point of the sintered body 1 and lower than the Ms point.

  The intermediate conveyance device 12 is a conveyance mechanism that conveys the sintered body 1 taken out from the quenching device 11 to the press device 13. The intermediate transfer device 12 includes a cover 21 that covers the transfer path of the sintered body 1 and a hot air generator 22 that sends hot air into the cover 21. With the hot air generated by the hot air generator 22, the atmosphere of the conveying path of the sintered body 1 can be maintained at a temperature higher than room temperature, and the temperature drop of the sintered body 1 during the conveyance can be suppressed.

  The press device 13 includes a mold 23 having a shape corresponding to the sintered body 1 and a mold cooling mechanism 24 that forcibly cools the mold 23. The mold cooling mechanism 24 is a device that feeds cooling water into a cooling water passage formed inside the mold 23. By cooling the mold 23 with the cooling water sent from the mold cooling mechanism 24 to the mold 23, the mold 23 when the sintered body 1 fed in order from the upstream side is continuously compressed by the mold 23. The temperature of the mold 23 immediately before compressing the sintered body 1 can be maintained at a temperature lower than the Ms point of the sintered body 1.

  The cooling and conveying device 14 covers the conveyor 26 that conveys the sintered body 1 discharged from the press device 13 toward the stacking unit 25 of the stacking device 15 and the conveyance path of the sintered body 1 by the conveyor 26. A conveyor cover 27 provided and a cooling gas supply device 28 for feeding cooling gas into the conveyor cover 27 are provided. The cooling and conveying device 14 conveys the sintered body 1 toward the stacking unit 25 by the conveyor 26 while spraying the cooling gas to the sintered body 1 by the cooling gas supply device 28.

  As shown in FIGS. 7 and 8, the conveyor 26 includes a tail pulley 30 disposed on the pressing device 13 side, a head pulley 31 disposed on the stacking device 15 side, and between the tail pulley 30 and the head pulley 31. It has a conveyor belt 32 and a conveyor frame 33 that supports the tail pulley 30 and the head pulley 31. An electric motor 34 (see FIG. 7) for rotating the tail pulley 30 is attached to the conveyor frame 33. The conveyor belt 32 can prevent the sintered body 1 from being damaged when a resin belt having a contact surface with the sintered body 1 formed of resin is used. Examples of such a resin belt include a chain type belt in which a large number of resin-made flat links are rotatably connected via joint pins. When using a chain type belt, the tail pulley 30 and the head pulley 31 are of a sprocket type having teeth on the outer periphery.

  The conveyor cover 27 has an opening 35 that allows the sintered body 1 to pass through on the inlet side and the outlet side of the conveyor 26, and has a shape that covers other portions. The cooling gas supply device 28 includes a cooling gas generator 36 (see FIG. 6) that generates a cooling gas having a temperature lower than that of the sintered body 1 being conveyed by the conveyor 26 (specifically, normal temperature or lower). A cooling gas introduction path 37 for introducing the cooling gas generated by the cooling gas generator 36 into the conveyor cover 27 is provided. The cooling gas is, for example, air. The normal temperature is 15 to 25 ° C.

  The stacking device 15 includes a horizontal disk-shaped stacking portion 25 and a lifting and conveying device 38 that lifts the sintered body 1 and stacks it on the stacking portion 25.

  As shown in FIG. 8, the lifting and conveying device 38 includes a chuck portion 40 that grips the outer periphery of the sintered body 1, a lift drive device 41 that moves the chuck portion 40 up and down, and a horizontal that moves the chuck portion 40 horizontally. And a driving device 42. A rotation driving device 43 that rotates the stacking unit 25 is provided below the stacking unit 25. The rotation drive device 43 rotates the stacking unit 25 intermittently (pitch feed).

  The stacking device 15 has a peripheral wall 44 along the outer periphery of the stacking portion 25, and the peripheral wall 44 prevents the sintered body 1 stacked on the stacking portion 25 from collapsing. The peripheral wall 44 is fixedly attached to the base frame 45 of the stacking device 15. Further, a guide plate 46 (see FIG. 7) that guides the crest of the sintered body 1 that moves in the circumferential direction with the rotation of the stacking portion 25 to the inner diameter side of the stacking portion 25 is connected to the peripheral wall 44. .

  Next, an example of a warm sizing method using the above-described warm sizing equipment will be described.

<Austenitization process>
The sintered body 1 is sequentially supplied from the upstream side to the mesh belt conveyor 17 of the heating furnace 10. The sintered body 1 on the mesh belt conveyor 17 is heated to a temperature higher than the Ae1 point by passing through the heating chamber 16, and is austenitized.

<Rapid cooling process>
The sintered body 1 is discharged from the heating furnace 10 and received by the quenching device 11. The sintered body 1 received by the rapid cooling device 11 is rapidly cooled from a temperature higher than the Ae1 point to a temperature lower than the Ae1 point and higher than the Ms point by being immersed in the oil bath 18. The cooling speed of the sintered body 1 at this time is a speed at which pearlite does not precipitate (that is, when the same speed is maintained and the temperature is cooled to a temperature lower than the Ms point, the structure of the sintered body 1 does not become pearlite. Cooling rate to become a site).

<Warm sizing process>
After the rapid cooling step, the sintered body 1 is transported from the rapid cooling device 11 to the press device 13 by the intermediate transport device 12. When the press device 13 receives the sintered body 1, the temperature of the sintered body 1 is lower than the Ae1 point and higher than the Ms point (for example, the Ms point is in the range of 150 to 200 ° C. In this case, about 220 to 280 ° C.). The press device 13 compresses the sintered body 1 with the mold 23 to plastically deform the sintered body 1 and corrects the size of the sintered body 1. At this time, the Ms point of the sintered body 1 temporarily rises due to the pressure applied when the sintered body 1 is compressed by the mold 23, and the heat conduction between the contact surfaces of the mold 23 and the sintered body 1 Since the sintered body 1 is rapidly cooled, the structure of the sintered body 1 undergoes martensitic transformation.

<Cooling transfer process>
The sintered body 1 discharged from the press device 13 is transported toward the stacking unit 25 while blowing a cooling gas by the cooling transport device 14. The temperature of the sintered body 1 immediately after being discharged from the press device 13 is, for example, about 80 to 120 ° C. in the case of the sintered body 1 having an Ms point in the range of 150 to 200 ° C. Then, the sintered body 1 is conveyed while being cooled by the cooling and conveying device 14, so that the temperature of the sintered body 1 immediately before reaching the stacking portion 25 is 60 ° C. or less (preferably 40 ° C. or less).

<Stacking process>
As shown in FIG. 8, the lifting and conveying device 38 repeats the operation of lifting and lowering the sintered body 1 at the outlet of the cooling and conveying device 14 onto the stacking portion 25, and the sintered body 1 is placed on the stacking portion 25. Pile up. Each time the sintered body 1 is stacked in a predetermined plurality of stages (for example, seven stages), the stacking portion 25 rotates by a certain angle. In this manner, the stacking device 15 sequentially stacks the sintered bodies 1 discharged from the press device 13 on the stacking portion 25, and forms a pile of the sintered bodies 1 on the stacking portion 25. At this time, the temperature of the stacking part 25 is normal temperature without temperature adjustment such as heating or cooling.

  By adopting the above-described warm sizing equipment and warm sizing method, it is possible to stably manufacture the sintered body 1 having high accuracy and high hardness.

  That is, when the sintered body 1 is discharged from the press apparatus 13, the temperature of the sintered body 1 is higher than room temperature (for example, about 80 to 120 ° C.). On the other hand, the stacking unit 25 on which the sintered bodies 1 discharged from the press device 13 are stacked is at room temperature.

  Here, if the sintered body 1 is transported as it is without spraying the cold air by the cooling and transporting device 14, the sintered body 1 stacked at the stacking portion 25 is sintered at the lowest position. Since the body 1 is in direct contact with the stacking unit 25 at room temperature, the body 1 is cooled to room temperature relatively quickly after being discharged from the warm sizing press device 13. On the other hand, among the sintered bodies 1 stacked on the stacking portion 25, the sintered body 1 at the second or higher level from the bottom is on the sintered body 1 below, so the stacking portion 25. Do not touch directly. Therefore, it is cooled to room temperature relatively slowly after being discharged from the warm sizing press device 13. As described above, when the sintered bodies 1 discharged from the press device 13 are sequentially stacked on the stacking portion 25, the sintered body 1 at the lowest position and the sintered bodies at the second and higher levels from the bottom are displayed. If the cooling rate is different from that of the bonded body 1 to room temperature, the dimensions of the sintered body 1 to be obtained (for example, even if the conditions such as the temperature and pressure of the mold 23 are the same) are small. There is a possibility that a variation of about plus or minus 10 μm) may occur.

  On the other hand, when the sintered body 1 is transported while blowing cool air with the cooling transport device 14 as in the above-described embodiment, the sintered body 1 is discharged from the press device 13 until reaching the stacking portion 25. In addition, since the sintered body 1 is cooled by the cooling and conveying device 14, the temperature of the sintered body 1 when reaching the stacking portion 25 is sufficiently low. Therefore, when the sintered bodies 1 are stacked in order on the stacking portion 25, the sintered body 1 at the lowest position and the sintered body 1 at the second or higher level from the bottom 1 is less likely to vary. Therefore, the sintered body 1 having high accuracy and high hardness can be manufactured stably.

  In order to confirm the effects of the embodiment of the present invention, the sintered body 1 (Example) transported while blowing cool air by the cooling transport device 14 and stacked on the stacking portion 25, and cold air blowing by the cooling transport device 14 are performed. A test was conducted to compare the dimensional accuracy of the sintered body 1 with the sintered body 1 (comparative example) that was transported as it was and stacked on the stacking portion 25. The sintered bodies 1 of the following examples and comparative examples are both inner rotors 2 having the shapes shown in FIGS. 1 and 2. The inner rotor 2 has a tooth root diameter of 29 mm, a tooth tip diameter of 34 mm, and an axial thickness of 10 mm.

<Example>
Three sets of operations were performed in which the sintered body 1 was transported while blowing cool air with the cooling and transporting device 14, and the sintered body 1 was stacked on the stacking portion 25 to form a mountain of the seven-stage sintered body 1. Then, each set of sintered bodies 1 is inserted inside the outer rotor 3 as shown in FIG. 5, and a chip clearance t formed between the outer teeth 5 of the inner rotor 2 and the inner teeth 4 of the outer rotor 3. Was measured (unit: μm). At this time, the outer rotor 3 was the same (master product). The tip clearance t was measured at six locations per inner rotor 2 by rotating the inner rotor 2 shown in FIG. The measurement results are shown in Table 1 and FIG.

  Examples H1, M1, and L1 are the sintered body 1 at the uppermost stage, the sintered body 1 at the center, and the sintered body 1 at the lowermost stage among the sintered bodies 1 stacked in the first set of seven stages. is there. Examples H2, M2, and L2 are the sintered body 1 at the uppermost stage, the sintered body 1 at the center, and the sintered body 1 at the lowermost stage among the sintered bodies 1 stacked in the 7th stage of the second set. is there. In Examples H3, M3, and L3, among the sintered bodies 1 stacked on the third stage of the third set, the uppermost sintered body 1, the central sintered body 1, and the lowermost sintered body 1 is there.

<Comparative example>
Three sets of operations are performed in which the sintered body 1 is transported as it is without blowing cold air by the cooling and transporting device 14, and the sintered body 1 is stacked on the stacking portion 25 to form a mountain of the seven-stage sintered body 1. It was. As in the embodiment, each set of sintered bodies 1 is inserted inside the outer rotor 3 as shown in FIG. 5, and between the outer teeth 5 of the inner rotor 2 and the inner teeth 4 of the outer rotor 3. The size (unit: μm) of the formed chip clearance t was measured. At this time, the outer rotor 3 was the same (master product). The tip clearance t was measured at six locations per inner rotor 2 by rotating the inner rotor 2 shown in FIG. The measurement results are shown in Table 2 and FIG.

  Comparative examples H1, M1, and L1 are the sintered body 1 at the uppermost stage, the sintered body 1 at the center, and the sintered body 1 at the lowermost stage among the sintered bodies 1 stacked in the first seven stages. is there. Comparative examples H2, M2, and L2 are the sintered body 1 at the uppermost stage, the sintered body 1 at the center, and the sintered body 1 at the lowermost stage among the sintered bodies 1 stacked in the seventh stage of the second set. is there. Comparative examples H3, M3, and L3 are the sintered body 1 in the uppermost stage, the sintered body 1 in the middle, and the sintered body 1 in the lowermost stage among the sintered bodies 1 stacked in the seventh stage of the third set. is there.

  Comparing FIG. 9 and FIG. 10, in FIG. 9, the dimensions of the examples H1 to H3, M1 to M3, and L1 to L3 are substantially horizontal. Moreover, about Example H1-H3, M1-M3, L1-L3, the range R which shows the difference of the maximum value and minimum value will be calculated, and the value will be 14. Further, when the standard deviation σ indicating the degree of dimensional variation was calculated, the value was 2.9.

  On the other hand, in FIG. 10, the dimensions of Comparative Examples H1 to H3 and M1 to M3 tend to be larger than the dimensions of Comparative Examples L1 to L3, and the dimensions are not uniform. Moreover, about the comparative examples H1-H3, M1-M3, and L1-L3, the range R which shows the difference of the maximum value and the minimum value will be calculated, and the value will be 19. Further, when the standard deviation σ indicating the degree of dimensional variation was calculated, the value was 5.2.

  As described above, in the example, the range R (the difference between the maximum value and the minimum value of the data) is smaller than that of the comparative example, and the standard deviation σ (the degree of data variation) is also suppressed to a small value. That is, it can be seen that the sintered product manufactured by the warm sizing method of the example is more stable in size than the sintered product manufactured by the warm sizing method of the comparative example.

DESCRIPTION OF SYMBOLS 1 Sintered body 2 Inner rotor 3 Outer rotor 4 Internal tooth 5 External tooth 6 Side surface 7 Side surface 10 Heating furnace 11 Quenching device 12 Intermediate conveyance device 13 Press device 14 Cooling conveyance device 15 Stacking device 16 Heating chamber 16a Inlet 16b Outlet 17 Mesh belt Conveyor 18 Oil tank 19 Input device 20 Extraction device 21 Cover 22 Hot air generator 23 Mold 24 Mold cooling mechanism 25 Stacking portion 26 Conveyor 27 Conveyor cover 28 Cooling gas supply device 30 Tail pulley 31 Head pulley 32 Conveyor belt 33 Conveyor frame 34 Electric motor 35 Opening 36 Cooling gas generator 37 Cooling gas introduction path 38 Lifting conveyance device 40 Chuck part 41 Lifting drive device 42 Horizontal drive device 43 Rotation drive device 44 Perimeter wall 45 Base frame 46 Guide plate t Chip clearance

Claims (3)

A heating furnace for heating the iron-based sintered body to a temperature higher than the austenitizing temperature (Ae1 point) to austenite;
The sintered body is received from the heating furnace, and the sintered body is rapidly cooled at a cooling rate at which pearlite does not precipitate from a temperature higher than the Ae1 point to a temperature lower than the Ae1 point and higher than the martensite transformation start temperature (Ms point). A quenching device,
The sintered body is received from the rapid cooling apparatus, and the sintered body having a temperature higher than the Ms point is compressed by a mold having a temperature lower than the Ms point, thereby correcting the size of the sintered body and martensitic transformation of the sintered body. A press device that simultaneously performs
A stacking device for sequentially stacking the sintered bodies discharged from the pressing device in a normal temperature stacking unit;
The stacking unit is disposed on the downstream side of the pressing apparatus and the upstream side of the stacking unit, and the sintered body is sprayed to the sintered body discharged from the pressing apparatus at a room temperature or lower temperature while blowing a cooling gas. A cooling and conveying device that conveys toward the
Having warm sizing equipment. The cooling and conveying device is
A conveyor for conveying the sintered body toward the stacking unit;
A conveyor cover provided to cover the conveying path of the sintered body by the conveyor;
A cooling gas supply device for feeding the cooling gas into the conveyor cover;
The warm sizing equipment according to claim 1, comprising: An austenitizing step of heating the iron-based sintered body to a temperature higher than the austenitizing temperature (Ae1 point) to austenite;
After the austenitizing step, the sintered body is rapidly cooled at a cooling rate at which pearlite does not precipitate from a temperature higher than the Ae1 point to a temperature lower than the Ae1 point and higher than the martensitic transformation start temperature (Ms point). When,
After the rapid cooling step, the sintered body having a temperature higher than the Ms point is compressed with a mold having a temperature lower than the Ms point, so that the dimension correction of the sintered body and the martensitic transformation of the sintered body are simultaneously performed. A warm sizing process;
After the warm sizing step, a stacking step of sequentially stacking the sintered bodies on the stacking portion at room temperature,
After the warm sizing process and before the stacking process, the sintered compact is transported toward the stacking section while blowing a cooling gas at normal temperature or lower temperature to the sintered compact discharged from the press device. Cooling and transporting process,
A warm sizing method.

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