JP2017006924A - Green compact molding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress occurrence of burning regardless of additive amounts of lubricant in compressing metal powder to mold a green compact.SOLUTION: In a green compact molding device 10, an outer die is constituted of a first annular member 16 and a second annular member 18 which moves between a fitting position and a non-fitting position relative to the first annular member 16. In a state where the second annular member 18 is at the fitting position, in an outer periphery of the first annular member 16 and an inner periphery of the second annular member 18 respectively are formed taper surfaces 16a, 18a so that elastic deformation of the first annular member 16 is accelerated to reduce a diameter thereof. Therefore, the device, when molding a green compact Wc, can accelerate the elastic deformation of the first annular member 16 to reduce the diameter of the member, and when taking out the green compact Wc, release the first annular member 16 from the elastic deformation, so that even if additive amounts of lubricant to metal powder is reduced before molding, friction at the time of slidably moving the first annular member 16 relative to the green compact Wc can be reduced so as to suppress occurrence of burning.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a green compact forming apparatus for forming a green compact by compressing metal powder.

  For example, as one method of manufacturing a metal part used in a vehicle or the like, a method of obtaining a metal part by compressing metal powder to form a green compact, and sintering the green compact to increase strength Further, forging a sintered body obtained by sintering a green compact is also performed (see, for example, Patent Document 1). In such a metal part manufacturing method, when forming a green compact, for example, a green compact forming apparatus 100 as shown in FIG. 4 is used. In the green compact molding apparatus 100, a molding space C is formed by an upper mold 112, a lower mold 114, and an annular outer mold 120, and the molding powder C is filled with metal powder Wp (FIG. 4A). By moving the upper mold 112 closer to the lower mold 114, the metal powder Wp is compressed to form the green compact Wc (FIG. 4B). When the green compact Wc is taken out, the upper mold 112 is raised and the outer mold 120 is slid downward to expose the green compact Wc (FIG. 4C). At this time, the contact stress is high between the inner peripheral surface 120a of the outer mold 120 forming the molding space and the green compact Wc. When the outer mold 120 is slid downward in this state, friction occurs. May cause seizure between the outer mold 120 and the green compact Wc (see reference A). For this reason, a lubricant for suppressing friction is added in advance to the metal powder Wp before being formed into the green compact Wc.

Japanese Patent No. 3774625

  However, when manufacturing a part that needs to be compressed to a high density, such as a core of a reactor, if an amount of lubricant equivalent to that for manufacturing a general part is added, the increase in density is hindered by the lubricant. Sometimes. For this reason, when manufacturing such high-density parts, it is necessary to reduce the amount of lubricant added, but if the amount added is reduced, the effect of suppressing friction cannot be sufficiently obtained, and seizure occurs. There was concern.

  The present invention has been made in view of the above problems, and its object is to generate seizure regardless of the amount of lubricant added when forming a green compact by compressing metal powder. It is to suppress.

(Aspect of the Invention)
The following aspects of the present invention exemplify the configuration of the present invention, and will be described separately for easy understanding of various configurations of the present invention. Each section does not limit the technical scope of the present invention. Therefore, while considering the best mode for carrying out the invention, some of the constituent elements in each section are replaced, deleted, or further added with other constituent elements. It can be included in the range.

  (1) A molding space is formed in such a manner that a pair of upper and lower molds are opposed to an annular outer mold, and the metal powder filled in the molding space is compressed by moving closer to at least one of the pair of upper and lower molds. The outer mold has a first annular member having an inner peripheral surface forming the molding space, and a second annular member disposed on the outer peripheral side of the first annular member. And a green compact forming apparatus including a diameter reducing mechanism for promoting elastic deformation of the first annular member to reduce the diameter.

  (2) In the above item (1), the outer mold has a first annular member having an inner peripheral surface forming the molding space, and a fitting position and a non-fitting that fits at least on the outer circumference of the first annular member. A second annular member movable between the first annular member and a second annular member movable between the first annular member and the second annular member in a fitted position. A green compact forming apparatus in which a tapered surface is formed on each of an outer periphery of one annular member and an inner periphery of the second annular member (Claim 1).

  (3) In the above item (2), there is provided control means for separately controlling at least one of the pair of upper and lower molds, the first annular member, and the second annular member. A compacting device.

  (4) A fitting position including a pair of upper and lower molds and an outer mold constituted by a first annular member and a second annular member, wherein the second annular member is fitted to at least the outer periphery of the first annular member; By using a green compact molding apparatus that can move between a non-fitting position and moving the second annular member to the fitting position, an outer periphery of the first annular member and an inner part of the second annular member A taper surface formed on each circumference is used to promote elastic deformation of the first annular member to reduce the diameter, and a molding space is formed in such a manner that the pair of upper and lower molds are opposed to the first annular member. , By moving at least one of the pair of upper and lower molds closer to the other, the metal powder filled in the molding space is compressed to form a green compact, and the second annular member is moved to the non-fitting position. To release the elastic deformation of the first annular member, At least one of the lower die together move away relative to the other, by moving the first annular member upward or downward, compact molding process to expose the powder compact.

  Since the present invention is configured as described above, it is possible to suppress the occurrence of seizure when the metal powder is compressed to form a green compact regardless of the amount of lubricant added.

It is an image figure showing roughly the composition of the compacting device concerning an embodiment of the invention. It is sectional drawing which shows a mode that a green compact is shape | molded with the green compact molding apparatus of FIG. FIG. 3 is a cross-sectional view showing step by step how the green compact is molded by the green compact molding apparatus of FIG. 1 following FIG. 2. It is sectional drawing which shows a mode that a compact is shape | molded with the conventional compacting apparatus.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Here, the same portions are denoted by the same reference numerals throughout the drawings. Detailed descriptions of the same or corresponding parts as in the prior art will be omitted.
FIG. 1 schematically shows a configuration of a green compact molding apparatus 10 according to an embodiment of the present invention. As shown in the figure, the green compact forming apparatus 10 includes a pair of upper and lower molds 12 and 14, an annular outer mold 20, and a control means 22. In the example of FIG. 1, the pair of upper and lower molds 12 and 14 is such that the upper mold 12 is a movable mold and the lower mold 14 is a fixed mold, and the upper mold 12 moves toward and away from the lower mold 14 (the upper and lower molds in FIG. Move in the direction). That is, the pair of upper and lower molds 12 and 14 has substantially the same configuration as the conventional upper and lower molds 112 and 114 shown in FIG. The tip surface 12a of the upper mold 12 and the tip surface 14a of the lower mold 14 have shapes corresponding to the shape of the green compact Wc (see FIG. 3) to be molded by the green compact molding apparatus 10. In addition, the upper mold | type 12 shown in FIG. 1 is the state retracted | saved to the uppermost position.

  The outer mold 20 is composed of a first annular member 16 and a second annular member 18, and the first annular member 16 and the second annular member 18 are at the lowest position in the retracted state shown in FIG. The position can be moved separately to the uppermost position (see FIGS. 2B and 2C) when forming the molding space C. Further, the second annular member 18 is fitted to the outer periphery of the first annular member 16 according to the relative positional relationship with the first annular member 16 (FIGS. 2B and 2C). 3 (d) and a non-fitting position (positions shown in FIGS. 1, 2 (a), 3 (e) and (f)). The first annular member 16 includes a tapered surface 16a inclined inward from the upper side to the lower side in FIG. 1, and an inner peripheral surface 16b that forms a molding space C described later. The second annular member 18 is provided with a tapered surface 18a inclined on the inner side from the upper side to the lower side in FIG. And the taper surface 16a of the 1st annular member 16 and the taper surface 18a of the 2nd annular member 18 are slidably contacted according to the positional relationship of the 1st annular member 16 and the 2nd annular member 18, and the 1st annular member A diameter-reducing mechanism for reducing the diameter of 16 is formed.

  The inner peripheral surface 16b of the first annular member 16 has a shape corresponding to the shape of the green compact Wc (see FIG. 3) formed by the green compact forming apparatus 10. The outer periphery of the first annular member 16 on which the tapered surface 16a is formed is formed in a circular shape, a shape following the shape of the inner peripheral surface 16b in plan view, or the like in plan view. For example, when the planar view shape of the inner peripheral surface 16b corresponding to the shape of the green compact Wc is substantially circular, the planar view shape of the outer periphery of the first annular member 16 corresponding to the shape is substantially circular. Moreover, when the planar view shape of the inner peripheral surface 16b of the first annular member 16 is substantially rectangular, the planar view shape of the outer periphery of the first annular member 16 may be circular, or the inner peripheral surface A substantially rectangular shape following 16b may be used. Further, the inner periphery of the second annular member 18 where the tapered surface 18a is formed is formed in a shape that follows the outer peripheral shape of the first annular member 16 in plan view. That is, the outer peripheral shape of the first annular member 16 and the inner peripheral shape of the second annular member 18 are such that the first annular member 16 is uniformly clamped by the second annular member 18 in the fitting position. Good. The second annular member 18 may be, for example, a discontinuous annular part provided with a notch or a crack, as long as the first annular member 16 can be tightened uniformly.

  Further, the first annular member 16 and the second annular member 18 are reduced in diameter by the second annular member 18 in the fitting position urging elastic deformation of the first annular member 16. The inner peripheral surface 16b of 16 and the front end surfaces 12a and 14a of the upper and lower molds 12 and 14 are formed in a size such that the molding space C can be formed without a gap. In other words, the first annular member 16 is formed so as to have a size that is slightly expanded in the normal time when the diameter is not reduced by the second annular member. Further, the inner circumference of the second annular member 18 is formed to have such a size as to reduce the diameter of the first annular member 16 in a state where it is in the fitting position.

  Further, the first annular member 16 and the second annular member 18 can reduce the diameter of the first annular member 16 by the second annular member 18 in the fitting position, and when the green compact Wc is formed. Made of a suitable material that can withstand pressure. For example, the first annular member 16 and the second annular member 18 may be formed of the same material as that of the conventional outer mold 120 shown in FIG. 4. For example, SKD (alloy tool steel) or super It can be formed of hard alloy V50 or the like. And the 1st annular member 16 and the 2nd annular member 18 may be formed with the same material, and may be formed with a different material.

  On the other hand, the control means 22 controls separately the positions of the movable upper mold 12, the first annular member 16 of the outer mold 20, and the second annular member 18. For example, the control unit 22 includes a moving mechanism similar to the moving mechanism for moving the conventional upper mold 112 shown in FIG. 4, thereby moving the upper mold 12 and moving the conventional outer mold 120. It is also possible to provide two sets of moving mechanisms similar to the moving mechanism for causing the first annular member 16 and the second annular member 18 to move separately. As such a moving mechanism, an appropriate moving mechanism according to the application, such as a hydraulic type or a mechanical type, can be used.

Next, a green compact forming method using the green compact forming apparatus 10 according to the embodiment of the present invention will be described with reference to FIGS. 2 and 3, illustration of the control means 22 is omitted.
First, as shown in FIG. 2A, the first annular member 16 and the second annular member 18 of the upper mold 12 and the outer mold 20 are in the retracted position, and the second annular member 18 is the first annular member. The first annular member 16 and the second annular member 18 are raised along the lower mold 14 by the control means 22 from the non-fitting position with respect to 16. At this time, the first annular member 16 and the second annular member 18 may be lifted at the same time while maintaining the positional relationship shown in FIG. After being raised to the position, the second annular member 18 may be raised to the uppermost position.

  In any of the above cases, the first annular member 16 and the second annular member 18 are finally moved to the uppermost position as shown in FIG. The two annular members 18 are fitted. Then, in the process in which the second annular member 18 moves from the non-fitting position to the fitting position, the tapered surface 16a on the outer periphery of the first annular member 16 and the tapered surface 18a on the inner periphery of the second annular member 18 that are in sliding contact with each other. The elastic deformation of the first annular member 16 is promoted through the first and second member 16 and the diameter of the first annular member 16 is reduced. As a result, in a state where the first annular member 16 is in close contact with the lower mold 14, an uncovered molding space C is formed by the inner peripheral surface 16 b of the first annular member 16 and the tip surface 14 a of the lower mold 14. .

  Subsequently, as shown in FIG. 2 (c), the metal powder Wp is filled into the molding space C having no lid. Lubricant may be added to the metal powder Wp in an amount that does not hinder the density increase of the green compact Wc to be molded later, or the lubricant may not be added. Then, with the metal powder Wp being filled in the molding space C, the upper die 12 is lowered by the control means 22 and the upper die 12 is brought closer to the lower die 14. When the upper mold 12 is lowered, the upper mold 12 eventually reaches the first annular member 16 and the upper end surface 12a of the upper mold 12 closes the molding space C. Further, the upper mold 12 is lowered, and as shown in FIG. 3 (d), a molding space C formed by the tip surfaces 12 a and 14 a of the pair of upper and lower molds 12 and 14 and the inner peripheral surface 16 b of the first annular member 16. , The metal powder Wp is compressed to form a green compact Wc having a predetermined density.

  When the molding of the green compact Wc is completed, as shown in FIG. 3E, the upper die 12 is raised by the control means 22 to expose the upper part of the green compact Wc. Further, with the position of the first annular member 16 maintained, only the second annular member 18 is lowered by the control means 22 to release the elastic deformation of the first annular member 16 whose diameter has been reduced, and the original state. To restore. Then, compared with the state in which the second annular member 18 is fitted, the first annular member 16 slightly expands in diameter, and the contact stress between the first annular member 16 and the green compact Wc is It is reduced from the state of being increased by the reduced diameter of the one annular member 16. Subsequently, as shown in FIG. 3 (f), the first annular member 16 is lowered by the control means 22 to expose the periphery of the green compact Wc. Then, in order to perform a sintering process or a forging process, the green compact Wc is taken out from the green compact forming apparatus 10, and the green compact forming method using the green compact forming apparatus 10 according to the embodiment of the present invention. Ends.

  Here, the green compact forming apparatus 10 illustrated in FIGS. 1 to 3 has a first annular member 16 and a second annular member as a diameter reducing mechanism for encouraging elastic deformation of the first annular member 16 to reduce the diameter. 18 and tapered surfaces 16a and 18a formed in sliding contact with each other. As another form of such a diameter reducing mechanism, for example, the second annular member 18 is constituted by a plurality of annularly arranged divided pieces, and the gap between adjacent divided pieces is narrowed and fitted to the outer periphery of the first annular member 16. A mechanism for reducing the diameter of the first annular member 16 by deforming into a fitted state and a non-fitted state in which the space between adjacent divided pieces is expanded to be in the fitted state can be used. In addition, the first annular member 16 is preferably configured as an integral member. However, if the molding space C can be formed with the upper and lower molds 12 and 14 without any gaps while being reduced in diameter by the diameter reduction mechanism, the first annular member 16 is annular. You may be comprised by the some division | segmentation piece arrange | positioned.

  In the green compact molding apparatus 10 shown in FIGS. 1 to 3, the upper mold 12 moves toward and away from the lower mold 14 that is a fixed mold, but according to the embodiment of the present invention. The green compact molding apparatus 10 is not limited to this. For example, both the upper and lower molds 12 and 14 may be movable. In FIGS. 1 to 3, both the first annular member 16 and the second annular member 18 are retracted downward, but the first annular member 16 is retracted upward to form the second annular member. 18 may be retracted downward. In the example of FIGS. 1 to 3, the second annular member 18 approaches the first annular member 16 from below, but it may approach from above. In this case, in order to reduce the diameter of the first annular member 16 by the second annular member 18, the taper is inclined outward from the upper side to the lower side with respect to the first annular member 16 and the second annular member 18. Surface 16a and tapered surface 18a are formed.

  Now, according to the embodiment of the present invention configured as described above, the following operational effects can be obtained. That is, the green compact molding apparatus 10 according to the embodiment of the present invention includes an outer mold 20 that forms a molding space C (see FIGS. 2 and 3) together with a pair of upper and lower molds 12 and 14, as shown in FIG. Is composed of the first annular member 16 and the second annular member 18. The first annular member 16 has an inner peripheral surface 16 b that forms a molding space C, and the second annular member 18 is disposed on the outer peripheral side of the first annular member 16. The green compact forming apparatus 10 reduces the diameter of the first annular member 16 by urging elastic deformation (the tapered surface 16a of the first annular member 16 and the tapered surface 18a of the second annular member 18). It has.

  With the above-described configuration, when the green compact forming apparatus 10 forms the forming space C, the first annular member 16 is elastically deformed by the diameter reducing mechanism as shown in FIGS. To reduce the diameter. The pair of upper and lower molds 12 and 14 are opposed to the first annular member 16 in a reduced diameter state, and the inner peripheral surface 16b of the first annular member 16 and the tip surfaces 12a and 14a of the upper and lower molds 12 and 14 are arranged. A molding space C surrounded by is formed. In addition, as shown in FIG. 3D, the green compact Wc is formed by compressing the metal powder Wp filled in the molding space C by moving the upper mold 12 closer to the lower mold 14. Done. That is, when the green compact Wc is formed, the first annular member 16 and the upper and lower molds 12 and 14 are sufficiently in close contact with each other in a state where the first annular member 16 is elastically deformed and reduced in diameter, and the metal powder Wp is fixed to a predetermined amount. Necessary and sufficient forming space C that can withstand the pressure for compressing to the density can be secured.

  On the other hand, when the green compact forming apparatus 10 according to the embodiment of the present invention takes out the formed green compact Wc, as shown in FIG. The elastic deformation is released, and the first annular member 16 is restored to the normal state. Then, the upper mold 12 is moved away from the lower mold 14 and the first annular member 16 in the normal state (expanded diameter) is moved downward, so that the pressure is increased as shown in FIG. With the powder Wc placed on the tip surface 14a of the lower mold 14, the periphery and upper part of the green compact Wc are exposed. At this time, the first annular member 16 slides with respect to the green compact Wc.

  That is, immediately after the molding is completed, when the contact stress between the green compact Wc and the first annular member 16 that has been increased by the elastic deformation of the first annular member 16 is taken out of the green compact Wc. This is reduced by releasing the elastic deformation state of the first annular member 16. For this reason, even if the first annular member 16 is slid relative to the green compact Wc, the friction between the green compact Wc and the first annular member 16 can be reduced. Accordingly, the green compact Wc can be obtained without reducing the addition amount of the lubricant for suppressing the friction between the green compact Wc and the outer mold 20 to the metal powder Wp or without adding the lubricant. It is possible to suppress the occurrence of seizure between the outer mold 20 and the outer mold 20. As a result, even when a metal part such as a reactor core that needs to be compressed at a high density is manufactured, the green compact Wc is stable without being inhibited by the lubricant while suppressing the occurrence of seizure. The density of can be increased.

  Further, the green compact molding apparatus 10 according to the embodiment of the present invention has a diameter reducing mechanism for reducing the diameter by encouraging elastic deformation of the first annular member 16 and the outer circumference of the first annular member 16 and the second annular member. This is realized by the tapered surfaces 16a and 18a formed on the inner periphery of the member 18, respectively. That is, the taper surface 16 a formed on the outer periphery of the first annular member 16 and the taper formed on the inner periphery of the second annular member 18 that can move to the fitting position that fits on the outer periphery of the first annular member 16. The surface 18a has a positional relationship in sliding contact with each other. For this reason, as shown in FIG. 2B, when the molding space C is formed, the second annular member 18 is brought into sliding contact with the first annular member 16 when the second annular member 18 is moved to the fitting position. The taper surfaces 16a and 18a are converted into an operation of encouraging elastic deformation of the first annular member 16 and reducing the diameter. Further, when the formed green compact Wc is taken out, as shown in FIG. 3E, if the second annular member 18 is moved from the fitting position to the non-fitting position, the first annular member 16 is elastically deformed. Is released, and the first annular member 16 is restored to the normal state. Thus, while realizing a diameter reduction mechanism with a simple configuration, the diameter reduction and restoration by elastic deformation of the first annular member 16 can be more reliably executed, and the occurrence of seizure can be suppressed.

  Furthermore, the green compact molding apparatus 10 according to the embodiment of the present invention is configured so that the upper mold 12 is moved toward and away from the lower mold 14, and the second annular member 18 is fitted to and disengaged from the first annular member 16. The movement to the alignment position and the movement of the first annular member 16 in the vertical direction are separately controlled using the control means 22 (see FIG. 1). Thereby, operations for forming the molding space C and molding the green compact Wc, which are executed in a state in which the elastic deformation of the first annular member 16 is promoted (FIGS. 2A to 2C, FIG. 3D). )) And the operation for exposing the green compact Wc (FIGS. 3 (e) and 3 (f)) executed in a state where the elastic deformation of the first annular member 16 is released, the position of each constituent member is appropriately set. It is possible to execute more reliably by controlling to.

  On the other hand, the green compact forming method according to the embodiment of the present invention is executed by using the green compact forming apparatus 10 according to the above-described embodiment of the present invention, thereby achieving the embodiment of the present invention. An equivalent effect corresponding to the green compact molding apparatus 10 is obtained.

  1, FIG. 2 (a), FIG. 3 (e) and FIG. 3 (f) show a state in which the first annular member 16 is not elastically deformed (not reduced in diameter). A gap can be confirmed between the member 16 and the lower mold 14. However, this gap is excessively illustrated in order to clearly show the difference between the state in which the first annular member 16 is reduced in diameter and the state in which the first annular member 16 is not reduced in diameter. In other words, the first annular member 16 and the lower mold 14 may be in contact with each other as long as the friction when the first annular member 16 slides relative to the green compact Wc can be reduced.

10: Green compact molding apparatus, 12: Upper mold, 14: Lower mold, 16: First annular member, 16a: Tapered surface, 16b: Inner circumferential surface, 18: Second annular member, 18a: Tapered surface, 20: Outer mold, Wp: metal powder, Wc: green compact, C: molding space

Claims (1)

A molding space is formed in a form in which a pair of upper and lower molds are opposed to an annular outer mold, and the metal powder filled in the molding space is compressed by compaction by approaching at least one of the pair of upper and lower molds. An apparatus for shaping a body,
The outer mold is movable between a first annular member having an inner circumferential surface forming the molding space and a fitting position and a non-fitting position at least fitted to the outer circumference of the first annular member. The outer periphery of the first annular member and the second annular member are configured so as to promote elastic deformation of the first annular member and reduce the diameter while the second annular member is in the fitting position. A green compact forming apparatus, wherein a taper surface is formed on each of the inner periphery of the member.

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