JP5700420B2 - Cylindrical gear forging method - Google Patents

Description

  The present invention relates to a forging method of a cylindrical gear having a tooth shape on the outer periphery.

  Conventionally, various forming methods have been proposed as a forging method of a cylindrical gear having a tooth shape on the outer periphery. For example, in the molding method disclosed in Patent Document 1, first, as shown in FIG. 8A, the material W100 is put into the molding die 120 having the tooth mold 121, and the preliminary punch 130 is lowered, so that the material W100. Preliminary holes 103 are formed. Next, as shown in FIG. 8B, the forming punch 150 is lowered while the preliminary punch 130 is lowered to press the material W100. Thereby, the meat of the raw material 100 is filled in the tooth mold 121 of the molding die 120, and the tooth profile 104 corresponding to the tooth mold 121 of the molding die 120 can be formed on the outer periphery of the raw material W100.

Japanese Patent Publication No.59-30499

  However, in the forming method disclosed in Patent Document 1, since the forming punch 150 is lowered while the preliminary punch 130 is lowered and the material W100 is pressed, the meat of the material W100 can flow only to the outer peripheral side, There is a problem that the molding load increases because the flow concentrates and the meat does not flow easily. As a result, the forming die is easily damaged, and the cost is increased due to the increase in size of the forming apparatus. In addition, since it is difficult for the meat to flow, there is a problem that it is difficult to fill the tooth mold 121 of the forming die 120 with the meat, and the tooth profile 104 is likely to be thin.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a forging method for a cylindrical gear having a low molding load and no lack of tooth profile.

The cylindrical gear forging method of the present invention is a preforming method in which a concave portion that is recessed in the axial direction and a convex portion that protrudes in the axial direction from the end portion of the tooth profile along the contour of the concave portion are formed on both end faces of the cylindrical material. A preform forming step for forming a product, a primary forming step for forming a cylindrical primary molded product by forming a preliminary hole penetrating in the axial direction by punching a concave portion of the preform, and a tooth mold on the inner periphery By holding the primary molded product in the molding die and pressing both end surfaces including the convex portion of the primary molded product in the axial direction, the flesh of the convex portion flows into the tooth mold of the molding die, and the primary molded product A secondary molding step for forming a secondary molded product by forming a tooth profile corresponding to the tooth die of the molding die on the outer periphery, and forming a through hole larger in diameter than the preliminary hole penetrating in the axial direction in the secondary molded product. And a tertiary forming step of forming a cylindrical gear.

  The second feature of the forging method for a cylindrical gear according to the present invention is that, in the secondary molding step, both end surfaces of the primary molded product are pressed by a pair of molding punches.

  The forging method of the cylindrical gear according to the present invention is such that, in the secondary molding step, both ends of the primary molded product are pressed with a pair of molding punches, and the tip portions of the pair of molding punches are press-fitted into the preliminary holes, and press-fitted into the preliminary holes. A third feature is that a predetermined gap is secured between the tip portions of the pair of molding punches.

In the forging method of the cylindrical gear according to the present invention, the concave portion has a conical shape in which the inner surface is inclined and widens toward the opening side, and the tip portions of the pair of molding punches have an acute angle compared to the inclination angle of the inner surface of the concave portion. In the secondary forming step, the fourth feature is to form the tooth profile by pressing the inner surfaces of the recesses with the tip portions of the pair of forming punches .

  The cylindrical gear forging method according to the present invention forms a primary molded product from a material held in a molding die in the primary molding process, and from the secondary molded product held in the molding die in the tertiary molding process. From the primary molding process to the secondary molding process with the primary molded product held in the molding die, and from the secondary molding process with the secondary molded product held in the molding die. A fifth feature is that it comprises a secondary transporting step for transporting to the tertiary forming step.

According to the forging method of the cylindrical gear according to the first feature of the present invention, the preformed product is formed by forming recesses and protrusions on both end faces of the columnar material in the preforming process, and the primary molding process. By punching out the concave portion of the preformed product, a preliminary hole is formed and a cylindrical primary molded product is formed. Then, after a tooth shape is formed on the outer periphery of the primary molded product in the secondary molding process and the secondary molded product is molded, a through hole is formed in the secondary molded product in the tertiary molding process and a cylindrical gear is molded. The Here, in the secondary molding step of molding the secondary molded product from the primary molded product, both end surfaces including the convex portion of the primary molded product are pressed in the axial direction, so that the meat of the convex portion is moved into the tooth die of the molding die. by flows, to form a tooth profile corresponding to the tooth form of the forming die to the outer periphery of the primary molded article. In this way, by forming preliminary holes in the primary molded product in the primary molding process and making it hollow, when pressing both end faces of the primary molded product in the secondary molding process, not only the outer peripheral side but also the hollow Meat can be flowed to the inner peripheral side. Thereby, by dispersing the flow of meat and facilitating the flow of meat, the molding load can be kept low. As a result, damage to the molding die can be suppressed, and an increase in cost due to an increase in the size of the molding apparatus can be avoided. Furthermore, it is possible to form a cylindrical gear without a lack of thickness in the tooth profile by facilitating the flow of the meat and facilitating the filling of the meat into the tooth mold of the forming die. In addition, in this case, by forming convex portions protruding in the axial direction on both end surfaces of the primary molded product in the primary molding step, when pressing both end surfaces of the primary molded product, It can be flowed to form a tooth profile with no lack of thickness.
Further, by forming the preliminary hole in the concave portion, it is possible to reduce the punching amount for forming the preliminary hole and to keep the molding load low.

  According to the forging method of the cylindrical gear of the second feature of the present invention, in the secondary molding step, both end surfaces of the primary molded product are pressed with a pair of molding punches, so that it is more than when only one end surface is pressed. By reducing the surface pressure acting on the molding punch, the molding load can be kept low. Furthermore, since both end surfaces of the primary molded product are pressed with a pair of molding punches, the meat is not biased to the other end surface and the lack of thickness on one end surface is likely to occur as in the case of pressing only one end surface. It is possible to form a tooth profile without lack of thickness.

  According to the forging method of the cylindrical gear of the third feature of the present invention, in the secondary molding step, both ends of the primary molded product are pressed with a pair of molding punches, and the tip portions of the pair of molding punches are used as spare holes. Since the press-fitting is performed, the flow of meat to the inner peripheral side is suppressed, and the amount of meat flow to the outer peripheral side is ensured, so that a tooth profile without lacking can be formed. Further, in the secondary forming step, since a gap of a predetermined interval is secured between the tip portions of the pair of forming punches press-fitted into the preliminary holes, while suppressing the flow of meat to the inner peripheral side as described above, A room for the meat to flow toward the inner peripheral side is left between the tip portions of the pair of molding punches, and the molding load can be kept low.

According to the fourth feature of the cylindrical gear forging method of the present invention, the recess has a conical shape in which the inner surface is inclined and widens toward the opening side, and the tip portions of the pair of molding punches are formed on the inner surface of the recess. In the secondary molding step, the inner surface of the recess is pressed by the tip portions of the pair of molding punches to form the tooth profile, so that a tooth profile without a lack of thickness can be formed.

  According to the cylindrical gear forging method of the fifth feature of the present invention, in the primary molding step, the primary molded product is molded from the material held in the molding die, and in the tertiary molding step, it is held in the molding die. A cylindrical gear is formed from the secondary molded product, and the primary molded product is held in the molding die while the primary molded product is held in the molding die, and the secondary molded product is held in the molding die. Since it is equipped with a secondary conveyance process that conveys from the secondary molding process to the tertiary molding process in the state, processing is performed without taking out the molded product from the molding die between the primary molding process and the tertiary molding process. Can do. Thereby, the generation | occurrence | production of the error of the process dimension by taking out from the shaping | molding die in each shaping | molding process can be suppressed, and a cylindrical gear with high dimensional accuracy can be shape | molded.

(A) is a cross-sectional front view of a raw material, (b) is a cross-sectional front view of a preformed product, (c) is a cross-sectional front view of a primary molded product, and (d) is a cross-sectional view of a secondary molded product. It is a front view, (e) is a cross-sectional front view of a cylindrical gear. It is a top view of a shaping | molding apparatus, (a) represents the state which shape | molds the molded product in each molding station, (b) represents the state which is conveying the molded product, respectively. It is a figure showing the formation process in the forge forming method of the cylindrical gear of the present invention. FIG. 4 is a partial cross-sectional view of a preforming station taken along line IV-IV in FIG. 2, in which the left half represents a state before the preforming process and the right half represents the preforming process. . It is a fragmentary sectional view of the primary forming station in the VV line of FIG. 2, The left half part represents the state before performing a primary shaping | molding process, and the right half part represents the state which is performing the primary shaping | molding process, respectively. . It is the fragmentary sectional view of the secondary molding station in the VI-VI line of FIG. 2, The left half part is the state before performing a secondary molding process, The right half part is the state which is performing the secondary molding process, respectively. Represents. It is the fragmentary sectional view of the tertiary shaping | molding station in the VII-VII line of FIG. 2, The left half represents the state before performing a tertiary shaping | molding process, and the right half represents the state which is performing the tertiary shaping | molding process, respectively. . (A) And (b) is a figure explaining the forge forming method of the conventional cylindrical gearwheel.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings. First, with reference to FIG. 1, the molded product shape | molded by the forging method of the cylindrical gear of this invention is demonstrated. 1A is a sectional front view of the material W0, FIG. 1B is a sectional front view of the preform W1, and FIG. 1C is a sectional front view of the primary molded product W2. 1 (d) is a sectional front view of the secondary molded product W3, and FIG. 1 (e) is a sectional front view of the cylindrical gear W4.

  In the forging method of the cylindrical gear of the present invention, first, the preform W1 shown in FIG. 1B is formed from the columnar material W0 shown in FIG. 1A, and the preform W1 shown in FIG. A cylindrical primary molded product W2 shown in 1 (c) is formed. Then, a secondary molded product W3 shown in FIG. 1D is molded from the molded primary molded product W2, and a cylindrical gear W4 shown in FIG. 1E is molded from the molded secondary molded product W3.

  The preform W1 is formed by forming concave portions 1 that are recessed in the axial direction and convex portions 2 that protrude in the axial direction on both end faces (E0, E0) of the material W0, and a preforming step S1 described later (see FIG. 4). ). The primary molded product W2 is formed by forming a preliminary hole 3 penetrating in the axial direction in the concave portion 1 of the preformed product W1, and is molded in a primary molding step S3 (see FIG. 5) described later. The secondary molded product W3 is obtained by forming a flat tooth profile 4 on the outer periphery of the primary molded product W2, and is molded in a secondary molding step S5 (see FIG. 6) described later. The cylindrical gear W4 is formed by forming a through hole 5 having a larger diameter than the preliminary hole 3 penetrating in the axial direction in the secondary molded product W3, and is molded in a tertiary molding step S7 described later.

  Next, with reference to FIG. 2, the shaping | molding apparatus 10 used for the forging shaping | molding method of the cylindrical gear of this invention is demonstrated. FIG. 2 is a plan view of the molding apparatus 10, (a) shows a state in which the molded products W 1, W 2, W 3, W 4 are molded at the molding stations 11, 12, 13, 14, and (b) shows a molded product. The states in which W1, W2, W3, and W4 are being conveyed are shown, respectively.

  As shown in FIG. 2, the molding apparatus 10 performs a preforming step S1 to form a preform W1 from a raw material W0, and performs a primary molding step S3 to transform the preform W1 from the preform W1. The primary molding station 12 for molding, the secondary molding station 13 for performing the secondary molding step S5 to mold the secondary molded product W3 from the primary molded product W2, and the cylindrical gear W4 from the secondary molded product W3 for performing the tertiary molding step S7. And a tertiary molding station 14. A rotatable turntable 15 is installed at the center of each molding station 11, 12, 13, and 14. Four turnable arms 16 having a molding die 20 at the tip are attached to the turntable 15. ing.

  The molded products W1, W2, W3, and W4 are held in the molding die 20, and as shown in FIG. It is thrown into. After the predetermined molding steps S1, S3, S5, and S7 are performed at each molding station 11, 12, 13, and 14, the arm 16 is contracted to turn the turntable 15 as shown in FIG. By rotating, the entire forming die 20 is conveyed to the forming stations 11, 12, 13, and 14 in the next process.

  The forming die 20 includes a tooth mold 21 corresponding to the tooth profile 4 of the cylindrical gear W4, and support molds 22 and 23 that support the tooth mold 21 from above and below (see FIGS. 4 to 7).

  Next, with reference to FIG. 3 to FIG. 7, the forging method of the cylindrical gear of the present invention will be described. FIG. 3 is a diagram illustrating a forming step in the forging method for a cylindrical material according to the present invention. 4 is a partial cross-sectional view of the preforming station 11 taken along the line IV-IV in FIG. 2. The left half is in a state before the preforming step S1, and the right half is in the preforming step S1. Respectively. FIG. 5 is a partial cross-sectional view of the primary molding station 12 taken along the line V-V in FIG. 2. The left half is the state before the primary molding step S3 and the right half is the primary molding step S3. Respectively. FIG. 6 is a partial cross-sectional view of the secondary molding station 13 taken along the line VI-VI in FIG. 2. The left half is the state before the secondary molding step S5 and the right half is the secondary molding step S5. Each state is shown. FIG. 7 is a partial cross-sectional view of the tertiary molding station 14 taken along the line VII-VII in FIG. 2. The left half is in a state before the tertiary molding step S7 and the right half is in the tertiary molding step S7. Respectively.

In the forging method of the cylindrical gear according to the present invention, as shown in FIG. 3, the preforming step S1, the preliminary conveying step S2, the primary forming step S3, the primary conveying step S4, the secondary forming step S5, the secondary conveying step S6, Each step is performed in the order of the tertiary forming step S7. First, in the pre-forming step S1, as shown in FIG. 4, both end faces (E0, E0) of the material W0 put into the forming die 20 are pressed in the axial direction by a pair of pre-punches 30, 30. Thereby, the recessed part 1 dented to an axial direction is formed in the both end surfaces (E0, E0) of the raw material W0, and the preformed product W1 is shape | molded.

  The preliminary punch 30 has a tip portion 31 having a shape corresponding to the recess 1 and a main body portion 32 having a diameter larger than that of the tip portion 31. As a result, in the pre-forming step S1, by pressing the both end faces (E0, E0) of the material W0 with the preliminary punch 30, the outer periphery of the tip portion 31 is filled with meat, and the both end faces (E0, E0) of the material W0. The convex part 2 which protrudes in an axial direction along the outline of the concave part 1 can be formed.

  In the preliminary transfer step S2, the arm 16 is contracted and the turntable 15 is rotated. Thus, the preform W1 is conveyed from the preforming station 11 to the primary molding station 12 while being held in the molding die 20 (see FIG. 2B).

  Next, in the primary molding step S3, as shown in FIG. 5, the concave portion 1 of the preform W1 held in the molding die 20 is punched out by the preliminary piercing punch 40. As a result, the preliminary hole 3 penetrating in the axial direction is formed in the concave portion 1 of the preform W1 to form the primary molded product W2. Thus, by forming the preliminary hole 3 in the recessed part 1, the punching amount for forming the preliminary hole 3 can be made small, and a shaping | molding load can be restrained low.

  In the primary conveyance process S4, the arm 16 is contracted and the turntable 15 is rotated. Thus, the primary molded product W2 is conveyed from the primary molding station 12 to the secondary molding station 13 while being held in the molding die 20 (see FIG. 2B).

  Next, in the secondary molding step S5, as shown in FIG. 6, both end faces (E2, E2) of the primary molded product W2 held in the molding die 20 are pressed in the axial direction by a pair of molding punches 50, 50. . Thereby, the tooth mold 21 of the molding die 20 is filled with meat, the tooth profile 4 is formed on the outer periphery of the primary molded product W2, and the secondary molded product W3 is molded. In this case, when the both end surfaces (E2, E2) of the primary molded product W2 are pressed by forming the preliminary holes 3 in the primary molded product W2 and making them hollow in the primary molding step S3, the arrows in FIG. As indicated by F, the meat can flow not only to the outer peripheral side but also to the hollow inner peripheral side. Thereby, a shaping | molding load can be restrained low by disperse | distributing the flow of meat and making it easy to flow meat. Further, by making the meat easy to flow and filling the tooth mold 21 of the forming die 20 with the meat easily, it is possible to form the tooth profile 4 having no lack of thickness. Further, since both end faces (E2, E2) of the primary molded product W2 are pressed by the pair of molding punches 50, 50, the surface pressure acting on the molding punch 50 is made smaller than when only one end face is pressed, The molding load can be kept low. Further, since both end faces (E2, E2) of the primary molded product W2 are pressed by the pair of forming punches 50, 50, one end face is biased toward the other end face as in the case of pressing only one end face. Therefore, it is possible to form the tooth profile 4 without the lack of thickness. In addition, in this case, both end surfaces (E2) of the primary molded product W2 are formed by forming the protruding portions 2 protruding in the axial direction on both end surfaces (E2, E2) of the primary molded product W2 in the primary molding step S3. , E2), it is possible to flow the flesh of the convex portion 2 to form the tooth profile 4 without a lack of thickness.

  The molding punch 50 has a tip 51 having a slightly larger diameter than the preliminary hole 3 of the primary molded product W2 and a main body 52 having a diameter larger than that of the tip 51. In the secondary molding step S5, The front end 51 is press-fitted into the preliminary hole 3 and the main body 52 presses both end faces (E2, E2) of the primary molded product W2. Thereby, when pressing the both end surfaces (E2, E2) of the primary molded product W2, the flow of the meat to the inner peripheral side is suppressed, and the flow amount of the meat to the outer peripheral side is ensured. No tooth profile 4 can be formed. In the secondary molding step S5, a predetermined interval (L) is secured between the tip portions 51, 51 of the pair of molding punches 50, 50 press-fitted into the preliminary holes 3. Thus, as described above, the flow of the meat toward the inner peripheral side is suppressed, but the room for the flow of the meat toward the inner peripheral side is left between the tip portions 51, 51 of the pair of forming punches 50, 50, thereby forming the mold. The load can be kept low.

  In secondary conveyance process S6, arm 16 is shrunk and turntable 15 is rotated. As a result, the secondary molded product W3 is conveyed from the secondary molding station 13 to the tertiary molding station 14 while being held in the molding die 20 (see FIG. 2B).

  Next, in the tertiary molding step S7, the secondary molded product W3 held in the molding die 20 is punched with a molding piercing punch 60 having a diameter larger than that of the preliminary piercing punch 40, as shown in FIG. Thereby, the cylindrical gear W4 is formed by forming the through-hole 5 having a larger diameter than the preliminary hole 3 penetrating in the axial direction in the secondary molded product W3.

  As described above, according to the forging method of the cylindrical gear of the present invention, by forming the preliminary hole 3 in the primary molded product W2 and making it hollow in the primary molding step S3, in the secondary molding step S5. When pressing both end faces (E2, E2) of the primary molded product W2, the meat can be flowed not only to the outer peripheral side but also to the hollow inner peripheral side. Thereby, a shaping | molding load can be restrained low by disperse | distributing the flow of meat and making it easy to flow meat. As a result, damage to the molding die 20 can be suppressed, and an increase in cost due to an increase in the size of the molding apparatus 10 can be avoided. Furthermore, by making it easy for the meat to flow and filling the tooth mold 21 of the forming die 20 with the meat, it is possible to form the cylindrical gear W <b> 4 having no lacking in the tooth profile 4.

  Further, according to the forging method of the cylindrical gear of the present invention, the primary molded product W2 is transported from the primary molding step S3 to the secondary molding step S5 while being held in the molding die 20 in the primary transport step S4. Since the secondary molded product W3 is transported from the secondary molding step S5 to the tertiary molding step S7 while being held in the molding die 20 in the secondary transporting step S6, between the primary molding step S3 and the tertiary molding step S7. The processing can be performed without taking out the molded products W2 and W3 from the molding die 20. Thereby, the generation | occurrence | production of the error of the process dimension by taking out from the shaping | molding die 20 in each shaping | molding process S3, S5, S7 can be suppressed, and the cylindrical gear W4 with high dimensional accuracy can be shape | molded.

  In this embodiment, spur teeth are formed as the tooth profile 4 of the cylindrical gear W4. However, the shape of the tooth profile 4 is not necessarily limited to spur teeth, and for example, helical teeth may be formed.

  Further, in the present embodiment, the preforming step S1 is performed before the primary forming step S3, and the preformed product W1 is formed by forming the recess 1 that is recessed in the axial direction on the material W0. However, the preforming step S1 is not necessarily performed. There is no need to perform the pre-forming step S1, and the primary molded product W2 may be formed by directly forming the preliminary hole 3 in the material W0. Thereby, the number of molding processes can be reduced and the molding time can be shortened.

  In the present embodiment, the tip 51 of the molding punch 50 is press-fitted into the preliminary hole 3 to press the both end surfaces (E2, E2) of the primary molded product W2, but the tip 51 is not necessarily press-fitted into the preliminary hole 3. It is not necessary to do so, and both end faces (E2, E2) of the primary molded product W2 may be simply pressed.

DESCRIPTION OF SYMBOLS 1 Concave part 2 Convex part 3 Preliminary hole 4 Tooth profile 5 Through-hole 20 Molding die 21 Tooth mold 30 Preliminary punch 50 Molding punch 51 Tip part (tip part of molding punch)
S1 Preliminary forming step S3 Primary forming step S4 Primary conveying step S5 Secondary forming step S6 Secondary conveying step S7 Tertiary forming step E0 End surface of material E2 End surface of primary formed product L Predetermined interval W0 Material W2 Primary formed product W3 Secondary formed product W4 cylindrical gear

Claims (5)

In the forging method of the cylindrical gear (W4) having the tooth profile (4) on the outer periphery,
A concave portion (1) recessed in the axial direction on both end faces (E0, E0) of the columnar material (W0) and the contour of the concave portion (1) project in the axial direction from the end of the tooth profile (4). A preforming step (S1) for forming the projection (2) to mold the preform (W1);
A primary molding step (S3) for forming a cylindrical primary molded product (W2) by forming a preliminary hole (3) penetrating in the axial direction by punching out the concave portion (1) of the preform (W1 ); ,
Both end faces (E2, E2 ) including the convex portion (2) of the primary molded product (W2) while holding the primary molded product (W2) in a molding die (20) having a tooth mold (21) on the inner periphery. ) In the axial direction, the flesh of the convex part (2) flows into the tooth mold (21) of the molding die (20), and the molding die is placed on the outer periphery of the primary molded product (W2). A secondary molding step (S5) of forming a tooth profile (4) corresponding to the tooth pattern (21) of (20) to mold the secondary molded product (W3);
A tertiary molding step (S7) for forming the cylindrical gear (W4) by forming a through hole (5) having a larger diameter than the preliminary hole (3) penetrating in the axial direction in the secondary molded product (W3); ,
A forging method of a cylindrical gear characterized by comprising:   The cylindrical gear according to claim 1, wherein in the secondary molding step (S5), both end faces (E2, E2) of the primary molded product (W2) are pressed by a pair of molding punches (50, 50). Forging method.   In the secondary molding step (S5), the pair of molding punches (50, 50) press both end faces (E2, E2) of the primary molded product (W2) and the pair of molding punches (50, 50). The tip portions (51, 51) are press-fitted into the preliminary holes (3), and a predetermined distance is provided between the tip portions (51, 51) of the pair of molding punches (50, 50) press-fitted into the preliminary holes (3). The method for forging a cylindrical gear according to claim 2, wherein a gap (L) is secured. The recess (1) has a conical shape in which the inner surface is inclined and widens toward the opening side,
The tip portions (51, 51) of the pair of molding punches (50, 50) have an acute angle compared to the inclination angle of the inner surface of the recess (1),
In the secondary molding step (S5), the tooth profile (4) is formed by pressing the inner surface of the recess (1) with the tip portions (51, 51) of the pair of molding punches (50, 50). A forging method of a cylindrical gear according to claim 3 . In the primary molding step (S3), the primary molded product (W2) is molded from the material (W0) held in the molding die (20), and in the tertiary molding step (S7), the molding die ( 20) molding the cylindrical gear (W4) from the secondary molded product (W3) held in the interior;
A primary conveyance step (S4) for conveying the primary molded product (W2) from the primary molding step (S3) to the secondary molding step (S5) in a state where the primary molded product (W2) is held in the molding die (20);
A secondary conveying step (S6) for conveying the secondary molded product (W3) from the secondary molding step (S5) to the tertiary molding step (S7) in a state of being held in the molding die (20);
The forging method of the cylindrical gear according to claim 1, wherein the forging method is provided.

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