JP4804291B2 - Manufacturing method of molded product having undercut portion - Google Patents

Description

  In the present invention, for example, a first upsetting part and a second upsetting part are formed at both ends along the axial direction by forging a cylindrical body such as a pipe material. The present invention relates to a method of manufacturing a molded product having an undercut portion capable of obtaining a molded product in which an undercut portion is provided between one upset molded portion and a second upset molded portion.

  Conventionally, it is known to manufacture a member having an undercut portion by forging.

  For example, Patent Document 1 discloses an annular projecting portion that is divided into a plurality of portions in the circumferential direction and projects inward in the radial direction corresponding to the shape of the contact surface and the undercut portion formed at one end portion in the axial direction. A lower mold that supports the member to be molded from the outside in the radial direction, and a seat surface that can come into contact with the abutment surface, and the axial direction from the abutment surface side to the radially outer side of the lower mold And an upper die that can be tightened from the radially outer side to the inner side.

  Further, Patent Document 2 includes a movable plate having a split-type knockout pin and a knockout pin, and guide means for guiding each split mold at a predetermined angle with respect to the movable direction of the split mold. A mold apparatus has been disclosed in which the time required for mold release is shortened to improve work efficiency by simultaneously performing the protrusion in one operation.

  Furthermore, Patent Document 3 is formed in a cylindrical shape having a through hole in the center, and annular flange portions protruding outward are formed at both end portions along the axial direction, respectively, on the outer periphery of one or the other annular flange portion. A toothed molded product having a tooth portion formed therein is disclosed.

JP 2002-346683 A Japanese Patent Laid-Open No. 9-239740 JP-A-6-114486

  However, in the technical idea disclosed in Patent Documents 1 to 3, it is only possible to bulge and form a single upset part by, for example, one forging (upset forming) process, The first upsetting part and the second upsetting part are formed almost simultaneously at both ends along the axial direction by one upsetting process, and the first upsetting part and the second upsetting part are formed. It is difficult to obtain a molded product in which an undercut part is provided between the parts.

  Further, the first movable punch and the second movable punch arranged coaxially are used, and the objects to be molded sandwiched between the first movable punch and the second movable punch are brought close to each other. It is conceivable to pressurize in the axial direction to bulge and form the first upsetting part and the second upsetting part at both ends along the axial direction.

  However, in this case, two driving mechanisms for driving the first movable punch and the second movable punch are required, and each of the first movable punch and the second movable punch is added. There is a problem that the amount of meat flow distributed to the first upsetting portion and the second upsetting portion must be adjusted by controlling the pressure.

  The present invention has been made in view of the above-mentioned problems and the like, and the first upsetting at both end portions along the axial direction is achieved by a simple single forging process that does not require adjustment of the amount of flow of meat to be distributed. An undercut portion in which a molded portion and a second upset molding portion are formed and a molded product having an undercut portion between the first upset molding portion and the second upset molding portion can be obtained. It aims at providing the manufacturing method of the molded article which has these.

  In order to achieve the above object, the present invention is manufactured through the following steps.

  First, a first upset molding portion is formed on one end side in the axial direction of the molded body, a second upset molding portion is formed on the other end side in the axial direction of the molded body, and To obtain an undercut molded product in which an undercut portion is formed between the first upset molded portion and the second upset molded portion, an upper annular side wall portion extending by a predetermined length parallel to the axial direction And a lower-side annular side wall portion continuous with the upper-side annular side wall portion as a molded body, and formed by a plurality of split dies and fixed dies that are urged displaceably by urging means. The object to be molded is loaded into the cavity.

  Subsequently, the punch is lowered, and a first mold portion of the punch plastically deforms the upper-side annular side wall portion of the molded body in a radially outward direction while the split mold surrounding the molded body is lowered. By performing upsetting, a first upsetting part is formed on one end side in the axial direction of the molded body.

  Then, the punch is further lowered, and the lower annular side wall is plastically deformed radially outward while the lower annular side wall is pressed by the punch and the split mold surrounding the workpiece is lowered. 2 upsetting. By the second upset molding, the plastically deformed meat flows into the second molding part of the split mold and is filled, so that the second upset molding part is formed on the other end side in the axial direction of the molded body. And an undercut part is formed between the first upset part and the second upset part by the undercut part of the split mold.

  As described above, according to the present invention, the first die and the first member are arranged in a floatable state using the split die biased by the biasing means, and pressurize the molding body in the axial direction by a single punch. The first upsetting part and the second upsetting part are formed substantially simultaneously on both end sides along the axial direction by the simple method of performing the upsetting process 2. A molded body in which an undercut portion is formed between the engraved molded portion and the second upset molded portion is obtained.

  The distribution of the meat flow between the first upsetting part and the second upsetting part is a split mold that abuts the boundary portion between the upper annular side wall part and the lower annular side wall part of the molded body. Made by the undercut part.

  The first upsetting part and the second upsetting part are formed at both ends along the axial direction by a simple method of pressing the workpiece in the axial direction with a single punch. A molded body having an undercut portion between the upsetting portion and the second upsetting portion can be obtained.

  Preferred embodiments of a method for producing a molded product having an undercut portion according to the present invention will be described in detail below with reference to the accompanying drawings.

  1A to 1C show a manufacturing process of the transmission gear 10 to which the manufacturing method of a molded product having an undercut portion according to the embodiment of the present invention is applied.

  The transmission gear 10 is manufactured through a plurality of forging processes described below. It should be noted that the steps shown in FIGS. 1A and 1B are preferably performed by warm or hot forging.

  First, as shown in FIG. 1A, a hollow cylindrical body 18 made of, for example, a metal pipe material and penetrating along the axial direction and having a through hole 14 having a constant inner diameter is prepared.

  One end side of the cylindrical body 18 along the axial direction has an upper annular side wall portion 20 extending in a predetermined length parallel to the axial direction and having a predetermined thickness, and on the other end side in the axial direction. Has a lower-side annular side wall portion 22 that is continuous to the upper-side annular side wall portion 20 and extends in a predetermined length in parallel with the axial direction and has a thickness equivalent to that of the upper-side annular side wall portion 20.

  Subsequently, the cylindrical body 18 is used as a molded body, and the cylindrical body 18 is subjected to upsetting using a forging apparatus described later, whereby a molded body (molded product) 24 as shown in FIG. 1B is obtained. can get.

  The molded body 24 is formed with a first upset molding portion 26a and a second upset molding portion 26b that are expanded in diameter by a predetermined length toward both ends along the axial direction. An undercut portion 28 is provided between the first upsetting portion 26a and the second upsetting portion 26b. The undercut portion 28 is recessed annularly by a predetermined length in the radial inward direction. In this case, the outer diameter of the side peripheral wall 30 of the first upset molding portion 26a on one end side is formed larger than the outer diameter of the side peripheral wall 32 of the second upset molding portion 26b on the other end side.

  The undercut portion 28 is substantially flat and extends along a horizontal direction substantially orthogonal to the axial direction through a corner R portion 34 having a curved cross section that is continuous with the side peripheral wall 30 of the first upsetting portion 26a. A first annular wall surface 36, a tapered portion 38 that is inclined by a predetermined angle with respect to the first annular wall surface 36 and gradually decreases in diameter toward the second upset molding portion 26b, and an axial direction continuous to the tapered portion 38 And a second annular wall surface 40 extending substantially parallel to the second annular wall surface 40 and a substantially flat third annular wall surface 42 extending along a horizontal direction that is continuous with the second annular wall surface 40 and substantially orthogonal to the axial direction. .

  In addition, it is provided so as to continue from the third annular wall surface 42 to the side peripheral wall 32 of the second upset molding portion 26b through the corner R portion 44.

  Subsequently, the first gear portion 48 and the second gear portion 50 are respectively formed on the side peripheral walls 30 and 32 of the first upset molding portion 26a and the second upset molding portion 26b by machining, and the transmission as a product. A gear 10 (see FIG. 1C) is obtained.

  Next, FIGS. 3 to 5 show a forging device 60 that performs the method for manufacturing a molded product having an undercut portion according to the present embodiment.

  This forging apparatus 60 performs upsetting with the cylindrical body 18 shown in FIG. 1A as the object to be molded.

  The forging apparatus 60 includes a die base 62, a knockout pin 64 that is displaceable in the vertical direction through a through-hole penetrating the center of the die base 62 under the driving action of an actuator (not shown), The sleeve 65 is connected to the tip of the knockout pin 64 and is provided so as to be able to move up and down together with the knockout pin 64. The sleeve 65 contacts the lower end of the cylindrical body 18 when the cylindrical body 18 is loaded in the cavity. The lower die 66 is disposed adjacent to the side of the lower die 66 and is substantially equally divided into four along the circumferential direction so as to surround the molded body and to be separated from the molded body when the mold is opened. And split mold 68 (see FIGS. 4 and 5).

  Further, in the forging apparatus 60, a tapered first annular guide surface 70a and a second annular guide surface 70b are formed on the inner wall to guide each of the divided dies 68 divided upward in the radial direction when the die is opened. The guide mold member 72, the support base 74 that supports the guide mold member 72, and the split molds 68 that are provided on the lower side of the guide mold member 72 and that are divided into four through the guide mold member 72. A spring member 76 that functions as an urging means that supports the floating support, and a cylindrical shape that surrounds the outer peripheral surface of the guide mold member 72, and abuts against the annular protrusion 72 a of the guide mold member 72. An annular step 78a for preventing the 72 from rising has a side member 78 formed on the inner wall.

  In this case, the split mold 68 is provided to be displaceable in the vertical direction by an urging means such as a spring member 76 provided on the lower side of the guide mold member 72. As shown in FIG. 2A, the split mold 68 is provided. In a state where no load is applied to 68, the position where the upper surface of the split mold 68 coincides with the alternate long and short dash line H is set as the initial position. The biasing means is not limited to a spring member such as a coil spring or a leaf spring that exerts an elastic force. For example, a buffer mechanism such as a gas spring or a pressure fluid (oil, air) is used. Also good.

  Further, the inner wall of the split mold 68 adjacent to the sleeve 65 projects radially inward (substantially in the horizontal direction) and contacts the boundary portion between the upper annular side wall 20 and the lower annular side wall 22 of the cylindrical body 18. It consists of an undercut molding portion 80 formed of an annular projection portion in contact with an annular concave portion formed on the lower side continuous from the undercut molding portion 80, and the lower side annular side wall portion 22 of the cylindrical body 18 is directed radially outward. A second molding portion 82 is provided for plastic deformation to form the second upset molding portion 26b.

  As shown in FIG. 6, the undercut forming portion 80 includes a curved portion 81a having a circular arc cross section, an abutting portion 81b that is continuous with the curved portion 81a and abuts against the object to be molded, and the abutting portion 81b. And a horizontal portion 81c extending substantially along the horizontal direction. Between the curved part 81a and the contact part 81b, there is provided a distribution point A for distributing the meat flow to the first upsetting part 26a and the second upsetting part 26b, as will be described later. In addition, as shown in the modification of FIG. 7, an undercut forming portion 80a in which the upper surface is a flat surface 81d and the distribution point A is provided at the chamfered portion may be configured.

  As shown in FIG. 6, the second molding portion 82 is provided on the lower side of the undercut molding portion 80, and the second molding portion 82 includes a horizontal plane formed by the horizontal portion 81 c and a vertical direction perpendicular to the horizontal plane. The surface 83a and the inclined surface 83b inclined by a predetermined angle with respect to the vertical surface 83a.

  Further, as shown in FIG. 3, the outer diameter side wall of the split mold 68 includes tapered surfaces corresponding to the first annular guide surface 70a and the second annular guide surface 70b of the guide mold member 72, respectively. A first annular inclined surface 84a and a second annular inclined surface 84b are formed to engage with the first annular guide surface 70a and the second annular guide surface 70b, respectively.

  Furthermore, the forging apparatus 60 includes an elevating member 86 provided so as to be movable up and down along a vertical vertical direction under the driving action of a ram (not shown), a punch holder 88 fixed to the elevating member 86, and the punch holder. And a punch 90 provided so as to be movable up and down along the vertical direction with respect to the lower mold 66 integrally with the lifting member 86 through 88.

  A first molding portion 92 for plastically deforming the upper annular side wall portion 20 of the cylindrical body 18 to form a first upset molding portion 26a at the tip portion of the punch 90, and the first molding portion 92 A counter punch portion 93 that is continuous and protrudes downward by a predetermined length is provided.

  A cylindrical sleeve member 94 that abuts the upper surface of the split mold 68 and regulates the outer diameter of the first upset molding portion 26a when forging is formed on the punch 90, and the sleeve member 94 is The holding member 96 fixed to the elevating member 86 is provided so as to be displaceable along the axial direction of the punch 90.

  In this case, the annular protrusion 94 a formed on the outer diameter surface of the upper end portion of the sleeve member 94 comes into contact with the annular protrusion portion 96 a formed on the inner diameter surface of the lower end portion of the holding member 96, so Is prevented from coming off. An annular recess 98 is formed on the inner wall of the sleeve member 94, and the lower end portion 88a of the punch holder 88 abuts against the bottom surface 99 of the annular recess 98, so that the lowering operation of the punch 90 is restricted. Reach the dead center.

  The forging apparatus 60 that performs the method for manufacturing a molded article having an undercut portion according to the present embodiment is basically configured as described above. Next, the upsetting process for the cylindrical body 18 is performed. A process is demonstrated in detail below based on FIG. 2A-FIG. 2F.

  First, the cylindrical body 18 shown in FIG. 1A is loaded into a cavity formed by the sleeve 65 of the lower mold 66 and the split mold 68 divided into four parts. Therefore, the lifting / lowering means (not shown) is energized to lower the punch 90 integrally with the lifting / lowering member 86. As shown in FIG. 2A, the counter punch portion 93 formed to protrude from the tip of the punch 90 has a cylindrical body. 18 and the first molding portion 92 of the punch 90 engages with the upper annular side wall portion 20 of the cylindrical body 18.

  In this case, the undercut forming portion 80 of the split mold 68 is in contact with the boundary portion between the upper annular side wall portion 20 and the lower annular wall portion 22 that is the outer surface of the cylindrical body 18, and the split die 68. Is biased to the initial position by biasing means such as the spring member 76 without being displaced downward.

  Subsequently, as shown in FIGS. 2B and 2C, when the punch 90 further descends toward the lower die 66, the state in which the counter punch portion 93 of the punch 90 is engaged with the inner wall of the cylindrical body 18 is maintained. The first forming portion 92 of the punch 90 starts the first upsetting molding in which the upper-side annular side wall portion 20 of the cylindrical body 18 expands in an oblique direction starting from the undercut forming portion 80, and the undercut forming portion is started. The flesh flows of the first upsetting part 26a and the second upsetting part 26b are respectively distributed starting from the part where 80 abuts (distribution point A).

  In this case, a first upset molding in which the upper-side annular side wall portion 20 of the cylindrical body 18 is plastically deformed corresponding to the shape of the first molding portion 92 of the punch 90 is performed, so that the first end-side first side is formed. An upsetting part 26a is formed. 2B and 2C, the split mold 68 is slightly changed by the deformation amount (deformation degree) of the first upsetting portion 26a due to the pressing force of the punch 90 and the pressing force of the punch 90. It will be in the state where it descended gradually corresponding to the balance of the forming force with the lower side annular side wall part 22 whose diameter expansion was started toward the second forming part 82.

  Subsequently, as shown in FIGS. 2D and 2E, the punch 90 further descends toward the lower mold 66, and the counter punch portion 93 of the punch 90 is engaged with the inner wall of the cylindrical body 18, and the punch 90 The first annular portion pressurizes the lower-side annular side wall 22 of the cylindrical body 18, and second upsetting is performed in which the lower-side annular side wall 22 is plastically deformed radially outward.

  That is, the first molding portion 92 of the punch 90 presses the lower annular side wall portion 22 of the cylindrical body 18 downward, so that the lower annular side wall of the cylindrical body 18 fixed by the sleeve 65 of the lower die 66. A reaction force is generated to press the portion 22 toward the upper side opposite to the pressurizing direction. Under the action of the reaction force, the second molding portion 82 formed by the annular concave portion of the adjacent split mold 68 is generated. The swelling of the plastically deformed meat is promoted (see FIGS. 2D and 2E).

  In order to smoothly flow and fill the plastically deformed meat to every corner in the second molding portion 82 of the split mold 68, as shown in FIG. The height H1 along the vertical direction of the surface formed at the boundary between the annular side wall part 20 and the lower side annular side wall part 22 is larger than the height H2 along the vertical direction of the horizontal part 81c of the undercut molding part 80. The molding condition is that it is set or at least set to the same height (H1 ≧ H2). The heights H1 and H2 along the vertical direction refer to heights in the vertical direction with respect to the arbitrarily set common reference plane on the lower side. FIG. 8 shows a state immediately before the meat about to start plastic deformation flows into the second forming portion 82 of the split mold 68.

  Next, as shown in FIG. 2F, the punch 90 is further lowered toward the lower mold 66, and the plastically deformed meat is split by the second upsetting with respect to the lower annular side wall portion 22 of the cylindrical body 18. The second forming portion 26b on the other end side is formed by flowing into the second forming portion 82, which is an annular recess 68, and filling it to every corner.

  As a result, as shown in FIG. 1B, the first upset molding portion 26a and the second upset molding portion 26b that are expanded in diameter by a predetermined length toward both ends along the axial direction are provided. Each of the molded bodies 24 is formed and has an undercut portion 28 between the first upset molding portion 26a and the second upset molding portion 26b.

  In this case, the split mold 68 is held at a predetermined position where the first upsetting force and the second upsetting force are balanced. That is, the split mold 68 held in a floating state by the urging means such as the spring member 76 has the first upsetting part 26a and the lower side annular side wall for plastically deforming the upper side annular side wall part 20 by the pressing force of the punch 90. The first upset molding force and the lower part for plastically deforming the upper-side annular side wall 20 after gradually descending corresponding to the respective deformation amounts of the second upset molding part 26b for slightly expanding the diameter of the part 22 It balances with the 2nd upsetting force which plastically deforms the side annular side wall part 22, and is hold | maintained in a predetermined position (refer FIG. 2F).

  The balance position of the split mold 68 is set in advance according to forging forming conditions such as the standby position of the punch 90 and the pressurizing force of the punch 90, and the lower end portion 88a of the punch holder 88 immediately before the completion of forming is the sleeve member 94. When the punch 90 reaches the bottom dead center by contacting the bottom surface 99 of the annular recess 98 formed on the inner wall of the mold, the material dimensions of the molded product are secured, so that the final balance position of the split mold 68 is set. Is done.

  Then, the first annular inclined surface 84a and the second annular surface 84a formed on the outer diameter side wall of the split mold 68 are pressed by pressing each split mold 68 divided upward through a pressing means (not shown) upward. The annular inclined surface 84 b is guided along the first annular guide surface 70 a and the second annular guide surface 70 b formed on the guide mold member 72. Therefore, when each split mold 68 moves upward on the radially outer side, the undercut molding portion 80 and the second molding portion 82 of the split mold 68 are separated from the molded product, and the mold opening is completed.

  In other words, at the time of upsetting, only the first annular guide surface 70a formed on the lower side of the inner wall of the guide mold member 72 and the second annular inclined surface 84b formed on the upper side wall of the split mold 68 were engaged. In this state, the split mold 68 is moved radially outward and upward, whereby the first annular guide surface 70a and the second annular guide surface 70b of the guide mold member 72 and the first annular inclination of the split mold 68 are obtained. The mold 84 is in a state where the surface 84a and the second annular inclined surface 84b are engaged with each other.

  Further, by raising the knockout pin 64 integrally with the lower mold 66 under the driving action of an actuator (not shown), the molded body raised from the center portion of the split mold 68 is held by a gripping means (not shown), whereby the next step It is transferred to.

  As described above, in the present embodiment, the split die 68 urged by the urging means including the spring member 76 and the like is used to place the cylinder 18 in a floating state, and the cylindrical body 18 is axially moved by the single punch 90. The first upsetting part 26a and the second upsetting part 26b are formed almost simultaneously at both end sides along the axial direction by a simple method of pressurization, and the first upsetting part 26a A molded body 24 in which an undercut portion 28 is formed between the second upset molding portion 26b is obtained.

  In this case, the distribution of the meat flow between the first upsetting part 26 a and the second upsetting part 26 b is distributed at the boundary portion between the upper side annular side wall part 20 and the lower side annular side wall part 22 of the cylindrical body 18. It is made by the distribution point A (see FIGS. 6 and 7) of the undercut forming portion 80 of the split mold 68 that abuts.

  When the object to be molded is a metal pipe material (cylindrical body 18), as shown in FIG. 9, the first upsetting part 26a side and the second upsetting part with the undercut forming part 80 as a boundary. 26b, there is no flow of meat, and the upper volume V1 and the lower volume V2 of the pipe material before molding that bounds the undercut molding portion 80 are the upper volume V1 and lower volume of the molded article after molding. It is configured to be the same as V2. Therefore, by using the material to be molded as a pipe material, it is possible to easily set the condition for distributing the meat to the first upsetting part 26a side and the second upsetting part 26b side.

  In the present embodiment, when the split mold 68 is opened, the first annular guide surface 70a and the second annular guide surface 70b of the guide mold member 72, and the first annular inclined surface 84a and the second second of the split mold 68 are used. Although the split mold 68 is moved upward in the radial direction by engaging with the annular inclined surfaces 84b, the split mold may be provided so as to expand its diameter by other methods.

FIG. 1A to FIG. 1C are longitudinal sectional views showing a transmission gear manufacturing process to which a method for manufacturing a molded product having an undercut portion according to an embodiment of the present invention is applied. 2A to 2F are longitudinal sectional views showing first and second upsetting processes for a molded body to which a method for manufacturing a molded article having an undercut portion according to an embodiment of the present invention is applied. . It is a longitudinal cross-section structure figure along the axial direction of the forge molding apparatus which enforces the manufacturing method of the molded article which has the undercut part which concerns on embodiment of this invention. It is a top view which shows the state which comprises the said forge molding apparatus and the split mold | die divided into 4 along the circumferential direction closed. It is a top view which shows the state which the said split mold opened. FIG. 3 is a partially enlarged longitudinal sectional view of the undercut forming portion showing a distribution point of the meat flow between the first upset forming portion and the second upset forming portion in the split die constituting the forging forming apparatus shown in FIG. 3. It is. FIG. 7 is a partially enlarged longitudinal sectional view showing a modification of the undercut forming part in FIG. 6. It is a partial expanded longitudinal cross-sectional view which shows the filling conditions of the meat with respect to the 2nd shaping | molding part of a split mold. When the pipe material is a molded body, and before and after molding, it is confirmed that there is no flow of meat between the first upsetting part and the second upsetting part with the undercut forming part as a boundary. It is an enlarged vertical sectional view shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Transmission gear 18 ... Cylindrical body 20 ... Upper side annular side wall part 22 ... Lower side side annular side wall part 24 ... Molded body 26a ... 1st upset molding part 26b ... 2nd upset molding part 28 ... Undercut part 60 ... Forging Molding device 64 ... Knockout pin 66 ... Lower die 68, 102 ... Split die 70a, 70b ... Annular guide surface 72 ... Guide die member 74 ... Support base 76, 104 ... Spring member 78 ... Side die member 80, 80a ... Undercut Molding part 82 ... second molding part 84a, 84b ... annular inclined surface 90 ... punch 92 ... first molding part 93 ... counter punch part

Claims (1)

A hollow cylindrical body composed of an upper annular side wall portion extending in parallel with the axial direction by a predetermined length and a lower side annular side wall portion continuous with the upper side annular side wall portion is a molded body, and can be displaced by a biasing means. Loading the molding into a cavity formed by a plurality of split molds and stationary molds biased by
The punch is lowered and the counter punch portion formed to protrude from the tip end portion of the punch is engaged with the inner wall of the cylindrical body, and the first mold of the punch is formed while the split mold surrounding the workpiece is lowered. The first upset molding is performed on one end side in the axial direction of the molded body by performing first upset molding in which the upper side annular side wall portion of the molded body is plastically deformed radially outward by the portion. Forming a part;
The punch is further lowered, the counter punch portion is kept engaged with the inner wall of the cylindrical body, and the punch pressurizes the lower annular side wall portion of the molded body to surround the molded body. Second upset molding is performed in which the lower annular side wall portion is plastically deformed radially outward while the mold is lowered, and the plastically deformed meat flows into the second molding portion of the split mold and is filled. As a result, a second upset molding portion is formed on the other end side in the axial direction of the molded body, and the first upset molding portion and the second upset molding portion are formed by the undercut molding portion of the split mold. A process in which an undercut portion is formed between
The manufacturing method of the molded article which has an undercut part characterized by having.

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