JP4533869B2 - Two-stage gear compaction mold - Google Patents

Description

  The present invention relates to a two-stage gear compacting mold for molding a two-stage gear by compressing a powder material.

  2. Description of the Related Art Conventionally, powdered materials such as metals and ceramics are compacted (pressurized) in a mold and sintered to obtain a sintered molded body having a desired shape.

  In this type of prior art, for example, Patent Document 1 discloses a two-stage gear in which a large-diameter gear portion is provided on the outer periphery of the disc portion, and a smaller-diameter gear portion projects from the central portion of the disc portion. An apparatus for molding is described.

Japanese Patent Laid-Open No. 5-195011

  By the way, the two-stage gear as described above tends to increase in weight because of the structure in which two gear portions are provided. However, depending on the use conditions, a sufficient weight reduction may be required while maintaining the necessary strength.

  Therefore, as a device for reducing the weight of the two-stage gear, for example, a two-stage gear 100 having a shape as shown in FIGS. 7 and 8 can be cited. In the two-stage gear 100, a first gear portion 104 is provided on the outer periphery of the disc portion 102, and a second gear portion 106 having a smaller diameter than the first gear portion 104 is projected from the center portion of the disc portion 102. . In the disk portion 102 between the first gear portion 104 and the second gear portion 106, for example, a plurality of hollow portions 108a having a substantially elliptical cross section and a hollow portion 108b having a substantially rectangular cross section are formed. In the two-stage gear 100, the provision of these hollow portions 108a and 108b achieves weight reduction with almost no loss of strength. In the two-stage gear 100, the through hole 109 provided in the center thereof is, for example, a hole through which the rotation shaft of the two-stage gear 100 is inserted.

  However, the above-mentioned prior art does not consider the two-stage gear compaction having a hollow portion as described above, and there is no description of the mold shape or the like.

  Therefore, as a compacting mold for molding the hollow portion of the two-stage gear, consider a shape shown in FIGS. 9 and 10, for example. The lower mold 110 (lower punch) shown in FIGS. 9 and 10 is a mold having a portion for molding the hollow portions 108a and 108b of the two-stage gear 100. In other words, the lower mold 110 has protrusions 112 a and 112 b corresponding to the shapes of the hollow portions 108 a and 108 b formed on one end surface of a ring-shaped mold 116 that is integrally formed with the gear molding mold 114. According to this configuration, the hollow portions 108a and 108b of the two-stage gear 100 can be easily compacted by the protrusions 112a and 112b by using an upper mold (not shown).

  However, in such a lower mold 110, it is recognized that stress concentration occurs in the vicinity of the root portions of the protrusions 112a and 112b at the time of compacting, and this stress concentration causes not only the root portion but also a ring in the vicinity thereof. It was confirmed that cracks and breakage occurred on the end surface of the metal mold 116 and the peripheral surfaces (standing surfaces) of the protrusions 112a and 112b.

  The present invention has been made in consideration of the above problems, and in a two-stage gear compacting mold for compacting a two-stage gear having a hollow portion, the hollow portion is formed during compacting. An object of the present invention is to prevent the occurrence of cracks and breakage by avoiding stress concentration on the root of the core mold for molding the core.

  In the two-stage gear compaction mold according to the present invention, a first gear portion is provided on the outer periphery of the disc portion, and a second gear portion having a smaller diameter than the first gear portion is provided at the center of the disc portion. A two-stage gear compaction mold for molding a two-stage gear in which a hollow part is formed between the first gear part and the second gear part in the disk part, A gear molding die for molding the second gear portion; a ring-shaped die for applying a compressive stress to the gear molding die; and a hollow portion projectably provided on one end surface of the ring-shaped die. The core mold and the ring mold are positioned and fixed to each other via a rotation preventing means.

  According to such a configuration, since the core mold for molding the hollow portion protrudes from one end surface of the ring-shaped mold in a separable manner, the base portion of the core mold at the time of compaction molding Stress concentration in the vicinity is avoided. Therefore, it is possible to prevent the core mold and the ring-shaped mold from being cracked or damaged due to the stress concentration. In addition, since the core mold and the ring mold are positioned and fixed to each other via the rotation preventing means, the core mold can be securely attached to the ring mold at a desired position (posture). In addition, by providing the rotation preventing means, the fixing position (posture) of the core mold does not shift.

  Further, when the rotation preventing means is constituted by a knock member inserted into a positioning hole formed in the core mold and the ring-shaped mold, the stress concentration occurs in the knock member. The knock member can be manufactured considerably more simply and at a lower cost than a core mold or a ring mold. For this reason, even if the knock member is cracked or damaged, it can be easily replaced. As a result, the durability (mold life) of the core mold or ring mold is greatly improved. Is possible.

  According to the present invention, the core mold for molding the hollow portion in the two-stage gear is provided on one end surface of the ring mold so as to be separable. For this reason, compared with the case where the core mold is formed integrally with the ring mold, stress concentration near the base portion of the core mold at the time of compacting is avoided, and the core mold or ring mold is avoided. It is possible to prevent the mold from cracking or breaking.

  Hereinafter, preferred embodiments of a two-stage gear compacting mold according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a partially exploded perspective view of a lower mold 10 (lower punch) constituting a two-stage gear compacting mold according to an embodiment of the present invention. FIG. 2 is a plan view of the lower mold 10 shown in FIG. 3 is a cross-sectional view taken along line III-III in FIG.

  The lower mold 10 is one of molds used when compacting (pressing) a two-stage gear 100 (see FIGS. 7 and 8), which is an example of a two-stage gear. This is a mold for molding the second gear portion 106 and the hollow portions 108a and 108b. 4 and 5, the lower mold 10 includes a lower outer punch 40, an upper mold 12 (upper punch), an upper outer punch 42, an upper step molding punch 44, and a tooth mold 14 (die). The two-stage gear 100 is compacted by being used together with the lower step forming punch 46 and the center core rod 48.

  The lower mold 10 includes a gear molding die 16 that molds the second gear portion 106 of the two-stage gear 100, and a ring that inserts the gear molding die 16 and molds the disk portion 102 of the two-stage gear 100. And a core mold 20a, 20b that projects from one end surface (the upper end surface in FIG. 1) of the ring-shaped mold 18 and molds the hollow portions 108a, 108b of the two-stage gear 100. The

  The gear molding die 16 has a substantially cylindrical shape, and a tooth mold 16a (gear mold) for molding the second gear portion 106 is formed on the inner peripheral surface. As shown in FIG. 3, the thickness t of the gear mold 16 is a sufficient thickness that can reliably withstand (accept) the compressive stress from the ring-shaped mold 18 described later, for example, the teeth of the tooth mold 16a. The thickness is sufficiently larger than the length h.

  The ring-shaped mold 18 has a cylindrical shape in which the gear molding mold 16 can be inserted into the through hole 18a, and the second gear of the disk portion 102 in the two-stage gear 100 at one end face (the upper end face in FIG. 1). The part 106 side is molded. The gear molding die 16 is inserted into the through hole 18a by shrink fitting, for example. In other words, the ring-shaped mold 18 and the gear molding mold 16 are arranged coaxially, and the inner circumferential surface of the ring-shaped mold 18 is in contact with the outer circumferential surface side of the gear molding mold 16, so that both It is fixed.

  Further, an internal thread portion 18b into which a bolt 22 for attaching the core dies 20a and 20b is screwed is formed in an annular shape on the one end face of the ring-shaped die 18. On the other hand, a female thread portion 23 for fixing the ring-shaped mold 18 (lower mold 10) to a molding device (not shown) is formed on the other end surface (lower end surface in FIG. 1) of the ring-shaped mold 18.

  The core molds 20a and 20b are molds for molding the hollow portions 108a and 108b of the two-stage gear 100 as described above, and have a block shape corresponding to the shapes of the hollow portions 108a and 108b. That is, the core mold 20a has a substantially oval cross section and molds the hollow part 108a, and the core mold 20b has a substantially rectangular cross section and molds the hollow part 108b.

  Moreover, the bolt hole 24 has penetrated in the center part of core metal mold | die 20a, 20b. Thereby, the core molds 20a and 20b are securely fastened and fixed to the one end face of the ring-shaped mold 18 by the bolts 22 and the female screw portions 18b.

  Then, as shown in FIG. 3, the vicinity of the opening end of the female screw portion 18b in the ring-shaped mold 18 and the opening of the bolt holes 24 in the core molds 20a and 20b on the ring-shaped mold 18 side (lower side in FIG. 3). In the vicinity of the end, positioning holes 26 and 28 communicating with the respective open ends are formed. A knock member 30 (see FIG. 1) having a shape obtained by cutting out a part of the circumferential surface of the cylindrical member is fitted into the positioning holes 26 and 28. That is, the positioning holes 26 and 28 have a shape (diameter cross-sectional shape) in which a part of a circle is cut out, as in the knock member 30 (see FIGS. 1 and 2).

  Therefore, in the lower mold 10, the core molds 20 a and 20 b are securely fixed at a desired position (posture) on one end surface of the ring-shaped mold 18 by the positioning action of the knock member 30 and the positioning holes 26 and 28. The Furthermore, since the knock member 30 and the positioning holes 26 and 28 are configured as described above, it is possible to prevent inconvenience that the core molds 20a and 20b rotate during use. Thus, the knock member 30 functions as a rotation preventing means (positioning means) for the core molds 20a and 20b together with the positioning holes 26 and 28.

  As the material of the lower mold 10, for example, powder high speed (high speed tool steel) is used for the upper end surfaces (punch) of the gear mold 16 and the ring mold 18, and the ring mold is used. For example, hot die steel (SKD61) is used for the outer peripheral portion 18, and carbide is used for the core molds 20 a and 20 b, for example.

  On the other hand, as shown in FIGS. 4 and 5, the lower outer punch 40 is a mold that molds the peripheral portion of the first gear portion 104 in the two-stage gear 100 together with the tooth mold 14. The lower outer punch 40 has a substantially cylindrical shape having a through hole 50, and a tooth mold 52 is provided around the outer peripheral surface. The lower mold 10 is inserted into the through-hole 50, and the tooth mold 52 meshes with a tooth mold 38 (gear mold) described later of the tooth mold 14. Since the tooth mold 52 and the tooth mold 38 need to be fitted and slid, the tooth mold 52 and the tooth mold 38 have an appropriate clearance so that the powder material for constituting the two-stage gear 100 does not enter.

  The upper mold 12 is a mold for molding the opposite side (the boss side) of the disc part 102 in the two-stage gear 100 to the second gear part 106 side. The upper mold 12 is inserted into a disk-shaped disk mold 32 that molds the boss side of the disk section 102 and a core mold insertion that is a relief section through which the core molds 20a and 20b of the lower mold 10 are inserted during compacting. It has the holes 34a and 34b and the through-hole 36 which penetrates center part. Further, through holes 35a and 35b pass through the central portions of the core mold insertion holes 34a and 34b.

  Similar to the lower outer punch 40, the upper outer punch 42 is a mold that molds the periphery of the first gear portion 104 in the two-stage gear 100 together with the tooth mold 14. The upper outer punch 42 has a substantially cylindrical shape having a through-hole 56, and a tooth mold 58 is provided around the lower portion of the outer peripheral surface. The upper mold 12 is inserted into the through-hole 56, and the tooth mold 58 meshes with the tooth mold 38 of the tooth mold 18. Since the tooth mold 58 and the tooth mold 38 need to be fitted and slid, the tooth mold 58 and the tooth mold 38 have an appropriate clearance so that the powder material for forming the two-stage gear 100 does not enter.

  The upper step forming punch 44 has a cylindrical shape having a through hole 60 penetrating the center portion. The upper step molding punch 44 is inserted into the through hole 36 of the upper mold 12 with its lower end surface being slightly offset above the disk mold 32 (see FIG. 5). This is a mold for molding a stepped portion (boss portion) at the periphery of the through hole 109 opposite to the gear portion 106 side.

  The tooth mold 14 is a mold that molds the first gear portion 104 of the two-stage gear 100 together with the lower outer punch 40 and the upper outer punch 42. The tooth mold 14 is formed in a cylindrical shape having a sufficient thickness so that it can withstand the internal pressure generated during compacting, and the first gear portion 104 of the two-stage gear 100 is molded on the inner peripheral surface thereof. A tooth mold 38 is formed. Then, the tooth mold 52 of the lower outer punch 40 and the tooth mold 58 of the upper outer punch 42 are inserted into and engaged with the tooth mold 38, and the tooth mold 52 and the tooth mold 58 are predetermined from the vicinity of the center in the height direction of the tooth mold 38. The first gear portion 104 is molded by being opposed to each other with a distance (the height of the first gear portion 104) offset.

  The lower step forming punch 46 has a cylindrical shape having a through hole 62 penetrating the center portion, and a tooth die 64 is provided around the outer peripheral surface. The lower step forming punch 46 is inserted and inserted with the upper end surface thereof being offset downward from the upper end surface of the ring-shaped mold 18 so that the tooth mold 64 meshes with the tooth mold 16 a of the lower mold 10. (Refer FIG. 5) It is a metal mold | die which shape | molds the end surface of the 2nd gear part 106 in the two-stage gear 100. FIG.

  The center core rod 48 has a stepped columnar shape including a large-diameter portion 66 and a small-diameter portion 68, and the large-diameter portion 66 fits from the through hole 62 of the lower step forming punch 46 to the through hole 60 of the upper step forming punch 44. By being inserted, it is a mold for molding the through hole 109 in the two-stage gear 100.

  Next, as an embodiment of the lower mold 10 basically configured as described above, the two-stage gear 100 shown in FIGS. 7 and 8 is sintered together with the upper mold 12, the tooth mold 14 and the like. The method and effect of powder molding will be described.

  First, the outer peripheral surface of the ring mold 18 of the lower mold 10 is fitted into the through hole 50 of the lower outer punch 40, and the outer peripheral surface of the upper mold 12 is inserted into the through hole 56 of the upper outer punch 42 (FIG. 5). reference). Next, the tooth mold 52 of the lower outer punch 40 is engaged with the tooth mold 38 of the tooth mold 14 and the lower step forming punch 46 and the center core rod 48 are inserted from below the tooth mold 16a of the lower mold 10. A molding material S in which the step gear 100 is molded is filled with a powder material (not shown). Thereafter, in a state where the upper step molding punch 44 is inserted into the through hole 36 of the upper mold 12 by a driving source (not shown), these are moved downwardly with respect to the lower mold 10 and the tooth mold 14 and simultaneously illustrated. By displacing the upper step forming punch 44 by a plunger that does not, the powder material is compacted (pressurized) (see FIG. 6).

  Then, the upper mold 12 and the upper outer punch 42 are separated from the lower mold 10 and the tooth mold 14, and the lower step mold punch 46 and the center core rod 48 are fitted and detached. By fitting / removing the mold 14, the two-stage gear 100 (molded body) having the shape shown in FIGS. 7 and 8 is obtained. Thereafter, the two-stage gear 100 (molded body) is transferred to a sintering apparatus (not shown) and sintered by the sintering apparatus to complete the two-stage gear 100 (sintered body). In addition, as the powder material constituting such a two-stage gear 100, in consideration of hardenability, for example, Fe (iron) is mainly used, and Ni (nickel), Mo (molybdenum), and Cu (copper) are mainly used. It is good to use what added etc.

  By the way, at the time of the compacting, as described above, in the lower mold 110 having the shape shown in FIGS. 9 and 10, stress concentration occurs in the vicinity of the roots of the protrusions 112a and 112b. There was a possibility that cracks and breakage would occur.

  On the other hand, in the lower mold 10 according to the present embodiment, the core molds 20a and 20b for molding the hollow portions 108a and 108b are fixed to one end face of the ring-shaped mold 18 by the bolts 22. That is, the core molds 20a and 20b have a split structure (a separable structure), and therefore stress concentration near the root portion is avoided. Therefore, in the lower mold 10, it is possible to reliably prevent the core molds 20a and 20b and the ring-shaped mold 18 from being cracked or damaged due to the stress concentration.

  The core molds 20a and 20b are attached to the ring-shaped mold 18 via knock members 30 and bolts 22. For this reason, it is conceivable that the stress generated in the core molds 20 a and 20 b during the compacting is concentrated on the knock member 30 and the bolt 22. However, the knock member 30 and the bolt 22 are considerably simpler and cheaper than the ring-shaped mold 18 and the like, and preparation of spare parts is relatively easy. Therefore, even if the knock member 30 and the bolt 22 are cracked or damaged, they can be easily replaced. As a result, the durability (mold life) of the lower mold 10 is greatly improved. Is possible.

  Further, during the compacting, a compressive stress as shown by an arrow A in FIG. 6 is applied from the ring-shaped mold 18 to the gear molding mold 16. At this time, in the ring-shaped mold 18, a higher compressive stress can be generated on the gear-molding mold 16 by the fastening reinforcement action by the bolts 22. Thereby, the 2nd gear part 106 is shape | molded by still higher precision and intensity | strength. Moreover, as described above, since the thickness t of the gear molding die 16 is sufficiently thicker than the tooth height h of the tooth die 16a, the gear molding die 16 is not bent and the compression is performed. The stress can be reliably transmitted to the tooth mold 16a.

  It should be noted that the present invention is not limited to the above-described embodiment, and it is naturally possible to adopt various configurations without departing from the gist of the present invention.

  For example, the shape of the two-stage gear 100 and the shapes of the hollow portions 108a and 108b in the two-stage gear 100 are not limited to the shapes shown in FIGS. Similarly, the shapes of the core molds 20a, 20b and the like are not limited to the shapes shown in FIG.

  Moreover, the shape of the knock member 30 and the positioning holes 26 and 28 into which the knock member 30 is inserted may be any shape that can prevent and position the core molds 20a and 20b. For example, the bolt 22 is at the center. A rectangle having a hole to be inserted may be used.

  Further, the molds used together with the lower mold 10 for molding the two-stage gear 100 are the lower outer punch 40, the upper mold 12, the upper outer punch 42, the upper step molding punch 44, and the tooth mold 14 as described above. The lower step forming punch 46 and the center core rod 48 are not limited, and any structure that can form the two-stage gear 100 by being used together with the lower mold 10 may be used.

It is a partial exploded perspective view of the lower mold which constitutes the two-stage gear compacting mold concerning one embodiment of the present invention. It is a top view of the lower mold | type shown in FIG. It is sectional drawing in line III-III of FIG. It is a perspective view for demonstrating each metal mold | die used for shaping | molding of a two-stage gear with the lower mold | type shown in FIG. It is a longitudinal cross-sectional view of the lower mold | type and each metal mold | die shown in FIG. It is a longitudinal cross-sectional view for demonstrating the state which has shape | molded the two-stage gear with the lower mold | type and each metal mold | die shown in FIG. It is a perspective view which shows the boss | hub side of the two-stage gear shape | molded by the lower mold | type and each metal mold | die shown in FIG. It is a perspective view which shows the 2nd gear part side of the two-stage gear shown in FIG. It is a top view which shows the metal mold | die which concerns on the lower mold | type comparative example shown in FIG. FIG. 10 is a cross-sectional view taken along line XX in FIG. 9.

Explanation of symbols

10, 110 ... Lower mold 12 ... Upper mold 14 ... Tooth mold 16, 114 ... Gear mold 16a, 38, 52, 58, 64 ... Tooth mold 18, 116 ... Ring mold 18a, 35a, 35b , 36, 50, 56, 60, 62, 109 ... through holes 18b, 23 ... female screw portions 20a, 20b ... core mold 22 ... bolt 24 ... bolt holes 26, 28 ... positioning hole 30 ... knock member 32 ... disk mold 34a, 34b ... Core mold insertion hole 40 ... Lower outer punch 42 ... Upper outer punch 44 ... Upper step molding punch 46 ... Lower step molding punch 48 ... Center core rod 100 ... Two-stage gear 102 ... Disc part 104 ... First gear part 106 ... 2nd gear part 108a, 108b ... Hollow part 112a, 112b ... Projection part

Claims (2)

A first gear part is provided on the outer periphery of the disk part, and a second gear part having a smaller diameter than the first gear part protrudes from the center part of the disk part,
A two-stage gear compacting mold for molding a two-stage gear in which a hollow part is formed between the first gear part and the second gear part in the disk part,
A gear molding die for molding the second gear part;
A ring-shaped mold for applying a compressive stress to the gear mold;
A core mold for forming the hollow portion, which is detachably protruded from one end surface of the ring mold;
The core mold and the ring-shaped mold are positioned and fixed to each other via a rotation preventing means. The two-stage gear compaction mold according to claim 1,
The two-stage gear dust molding mold, wherein the rotation preventing means comprises a knock member inserted into a positioning hole formed in the core mold and the ring mold.

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