Forging device and gear manufacturing method

Abstract

To provide a forging device capable of shortening at least the overall man-hour, and more preferably, enabling the fine adjustment of molding shape without replacing the device.SOLUTION: A forging device is equipped with a punch 2 that moves downward to press work W downward, a counter punch 3 that is disposed under the punch 2 and on which the work W is placed, a reaction force applying device 4 that applies reaction force to the downward movement of the counter punch 3 due to the pressing of the punch 2, an annular molding die 5 that is formed with a molding groove 5a on an inner peripheral surface, an annular ring member 6 that is disposed on an outer peripheral side of the molding die 5 and is configured to change pressing force for pressing the molding die 5 according to a vertical position, a driving portion 7 that vertically moves the ring member 6, a detecting portion 8 that detects vertical positional information on the punch 2, and a control portion that controls the driving portion 7 on the basis of a detection result of the detecting portion 8.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a forging device and a method for manufacturing a gear. [Background technology]

[0002] The technology of the forging device is described, for example, in JP 2017-209699 A. This publication discloses a forging device that cold forges an intermediate cylindrical gear having a tooth profile formed therein to form a gear with a crowning. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-209699 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the forging device, it is necessary to perform crowning separately after forming the intermediate cylindrical gear once, so the total number of steps is increased. In addition, since the structure of the die is complicated, it is difficult to fine-tune the crowning. For example, if the friction resistance of the forming die changes with age, the shape of the crowning may change.

[0005] The object of the present invention is to provide a forging device capable of shortening the total man-hours, and more preferably to provide a forging device capable of fine-tuning the formed shape without replacing the device. Another object of the present invention is to provide a gear manufacturing method capable of forming a tooth profile with good firmness in the gear manufacturing using a forging device. [Means for solving the problem]

[0006] A forging apparatus according to a first embodiment of the present invention comprises a punch that moves downward to press a workpiece downward, a counter punch that is arranged below the punch and on which the workpiece is placed, a reaction force applying device that applies a reaction force against the downward movement of the counter punch due to the pressure of the punch, an annular forming die having a forming groove formed on its inner surface, an annular ring member that is arranged on the outer periphery of the forming die and is configured to change the pressing force pressing the forming die depending on the state, a drive unit that changes the state of the ring member, a detection unit that detects vertical position information of the punch, and a control unit that controls the drive unit based on the detection results of the detection unit.

[0007] A forging apparatus according to a second embodiment of the present invention comprises a punch that moves downward to press a workpiece downward, a counter punch that is positioned below the punch and on which the workpiece is placed, a reaction force applying device that applies a reaction force against the downward movement of the counter punch due to the pressure of the punch, a ring-shaped forming die having a forming groove formed on its inner surface, a detection unit that detects vertical position information of the punch, and a control unit that controls the reaction force applied by the reaction force applying device based on the detection result of the detection unit.

[0008] A forging device according to a third embodiment of the present invention comprises a punch that moves downward to press a workpiece downward, a counter punch that is arranged below the punch and on which the workpiece is placed, a ring-shaped forming die having a forming groove formed on its inner surface, and a collar member that is arranged around the counter punch or a moving member that is an interlocking member that moves downward in conjunction with the downward movement of the counter punch and generates a frictional force against the downward movement of the moving member, and the moving member and the collar member are configured so that the frictional force changes depending on the position of the moving member.

[0009] A fourth aspect of the present invention relates to a gear manufacturing method using a forging apparatus including a punch that moves downward to press a workpiece downward, a counter punch that is arranged below the punch and on which the workpiece is placed, a reaction force applying device that is configured to apply a reaction force against the downward movement of the counter punch due to the pressing of the punch and to output the reaction force as a fluid pressure, and an annular forming die having a tooth-shaped forming groove formed on its inner surface, and includes a drawing process in which the workpiece, the outer diameter of which is larger than the minimum inner diameter of the forming die, is pressed into the forming die, and in the drawing process, with the reaction force applied to the counter punch by the reaction force applying device, the punch presses the workpiece into the forming die to compressively deform the workpiece.

[0010] A forging apparatus according to a fifth embodiment of the present invention comprises a punch that moves downward to press a workpiece downward, a counter punch that is arranged below the punch and on which the workpiece is placed, a reaction force applying device that applies a reaction force against the downward movement of the counter punch due to the pressure of the punch, a ring-shaped forming die having a forming groove formed on its inner surface, and a pressing force adjusting means that changes the inner diameter of the forming die by adjusting the pressing force applied to the outer surface of the forming die. Effect of the Invention

[0011] According to the first embodiment of the present invention, the ring member presses the forming die with a pressing force according to the state, thereby elastically deforming the forming die and changing its inner diameter. The greater the pressing force of the ring member, the more the forming die is tightened radially inward, and the smaller its inner diameter. In other words, the radial dimension of the tooth profile can be changed during forming. The smaller the diameter of the forming die, the smaller the shape of the forming groove (groove width, etc.) becomes similarly. As a result, when forming a gear with a crowning, for example, the control unit changes the pressing force according to the position of the punch to change the inner diameter of the forming die, making it possible to form a gear with a crowning with one punch (without forming an intermediate cylindrical gear). In addition, according to this configuration, the forming shape can be finely adjusted by adjusting the reaction force and / or pressing force, so that even if a change in frictional resistance occurs, it is not necessary to replace the device.

[0012] According to the second embodiment of the present invention, the degree of deformation of the workpiece can be changed by changing the reaction force according to the position of the punch. In other words, the greater the reaction force, the greater the clamping force in the vertical direction on the workpiece, and the greater the amount of radial outward bulging of the workpiece. As a result, when forming a gear with a crowning, for example, the control unit can change the reaction force according to the position of the punch, making it possible to form a gear with a crowning with a single punch (without forming an intermediate cylindrical gear). Furthermore, according to this configuration, the formed shape can be finely adjusted by adjusting the reaction force, so there is no need to replace the device even if a change in frictional resistance occurs. In this way, according to the first and second aspects of the present invention, the total number of steps can be reduced, and fine adjustment of the molded shape becomes possible without replacing the device.

[0013] According to the third embodiment of the present invention, the frictional force between the moving member and the collar member changes depending on the position of the moving member (counter punch or interlocking member), thereby making it possible to change the reaction force during punching. This makes it possible to change the degree of deformation of the workpiece, as in the second embodiment. In other words, the greater the reaction force (frictional force), the greater the amount of radial outward bulging of the workpiece. This makes it possible, for example, to form a gear with a crowning with a single punch (without forming an intermediate cylindrical gear) without special control.

[0014] According to the fourth embodiment of the present invention, the drawing (compression) is performed while a reaction force (penetration resistance) due to fluid pressure is applied to the workpiece. This assists the flow of the workpiece (material) to the tooth tip during the formation of the tooth profile. In other words, the pressing force of the workpiece (material) against the bottom surface of the forming groove increases during forming. In other words, a tooth profile with good firmness is formed.

[0015] According to the fifth aspect of the present invention, as in the first aspect, the pressing force is adjusted by the pressing force adjusting means, so that the inner diameter of the forming die can be changed during forming, thereby achieving the same effects as in the first aspect. [Brief description of the drawings]

[0016] [Figure 1] 1 is a configuration diagram of a forging device according to a first embodiment. FIG. [Diagram 2] 4 is a conceptual diagram showing the shape of a forming groove in the first embodiment (as viewed in the groove extending direction). FIG. [Diagram 3] FIG. 2 is a conceptual diagram (a cross-sectional explanatory diagram seen from the side) showing the configuration of a forming groove in the first embodiment. [Figure 4] 5A to 5C are conceptual diagrams for explaining the position and pressing force of the ring member in the first embodiment. [Diagram 5] FIG. 2 is a conceptual diagram of crowning in the first embodiment. [Figure 6] FIG. 2 is a diagram showing a workpiece after forming in the first embodiment is completed. [Figure 7] FIG. 6 is a configuration diagram of a forging device according to a second embodiment. [Figure 8] FIG. 11 is a configuration diagram of a forging device according to a third embodiment. [Figure 9] FIG. 13 is a conceptual diagram (sectional view) for explaining a first knockout pin and a collar member according to a third embodiment. [Figure 10] FIG. 11 is a conceptual diagram showing another example of the workpiece according to the present embodiment. [Figure 11] 10 is a conceptual diagram for explaining another example of the workpiece and the forging device of the present embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are given the same reference numerals in the drawings. In addition, each drawing used in the description is a conceptual diagram. In addition, in this description, the fixing is, for example, screw fixing. In the drawings, the screw used for screw fixing and the fact that the inside of the member is hollow (for example, cylindrical) are omitted. In addition, in FIG. 1, the left side of the two-dot chain line represents the state at the start of forming, and the right side represents the state after forming is completed. In addition, in FIG. 7, the left side of the two-dot chain line represents the initial position of the device, and the right side represents the state after forming is completed. The forging device is symmetrical, and for the sake of illustration in the drawings, the reference numerals in FIG. 1 and FIG. 7 are given to only one of the left and right for each member.

[0018] First Embodiment A first embodiment will be described by taking a forging device for forging a gear with crowning as an example. A workpiece W to be formed is formed in an annular (cylindrical) shape. The forging device 1 of the first embodiment is an electric servo press.

[0019] 1, the forging device 1 of the first embodiment includes a punch 2, a counter punch 3, a gas cylinder (corresponding to a "reaction force applying device") 4, a forming die 5, a ring member 6, a drive unit 7, a detection unit 8, and a control unit 9. The punch 2 is an upper punch member that moves downward to press a workpiece W downward. The punch 2 includes an inner punch portion 21, an outer punch portion 22, and a moving portion 23.

[0020] The inner punch portion 21 is a cylindrical punch member fixed to the moving portion 23 and extending downward from the moving portion 23. The outer punch portion 22 is a cylindrical punch member arranged on the outer peripheral side of the inner punch portion 21. The outer punch portion 22 is engaged with the moving portion 23 so as to be slidable in the vertical direction. The inner punch portion 21 is arranged so as to be slidable relative to the outer punch portion 22. At least from the start to the completion of forming, the lower end of the inner punch portion 21 is located below the lower end of the outer punch portion 22. The workpiece W is arranged below the lower end surface 22a of the outer punch portion 22.

[0021] The moving part 23 is a member that moves in the vertical direction under the control of the control unit 9. A recess 231 that opens downward is formed in the moving part 23. A protrusion 231a is formed at the opening of the recess 231. Therefore, the upper end (flange part) 221 of the outer punch part 22 engages with the protrusion 231a and becomes slidable between the bottom surface 231b of the recess 231 and the protrusion 231a. The inner punch part 21 is fixed to the center part of the bottom surface 231b of the recess 231 (the upper end part of the moving part 23). Therefore, the inner punch part 21 moves together with the movement of the moving part 23.

[0022] When the moving part 23 moves downward, the outer punch part 22 moves downward by abutting against the bottom surface 231b. When the moving part 23 moves upward, the outer punch part 22 moves upward by abutting the protrusion 231a and the upper end part 221. At the start of forming, the outer punch part 22 abuts against the bottom surface 231b. Therefore, from the start of forming to the completion, the outer punch part 22 moves together with the downward movement of the moving part 23.

[0023] The counter punch 3 is disposed below the punch 2 and is a lower punch member on which the workpiece W is placed. The counter punch 3 is disposed opposite the punch 2. The workpiece W is disposed between the punch 2 and the counter punch 3. The counter punch 3 moves downward due to the downward pressure applied by the punch 2. The counter punch 3 is equipped with a pressure-receiving portion 31, a columnar portion 32, and a cylindrical portion 33 from the bottom.

[0024] The pressure-receiving part 31 is disk-shaped, and the pressure transmission part 44 of the gas cylinder 4 abuts against its lower surface. The pressure-receiving part 31 is pressed upward by the gas cylinder 4 in response to the downward movement of the counter punch 3. The columnar part 32 is a columnar part extending upward from the upper end surface of the pressure-receiving part 31.

[0025] The cylindrical portion 33 has the same outer diameter as the columnar portion 32 and is a cylindrical portion extending upward from the upper end surface of the columnar portion 32 coaxially with the columnar portion 32. The upper end surface of the cylindrical portion 33 faces the lower end surface 22a of the outer punch portion 22 (the step surface of the punch 2). In other words, during forming, the workpiece W is sandwiched between the lower end surface 22a of the outer punch portion 22 and the cylindrical portion 33 of the counter punch 3. At the upper end of the counter punch 3, a recess 30 is formed by the cylindrical portion 33 and the upper end surface of the columnar portion 32. The inner punch portion 21 enters the recess 30 in response to the downward movement of the punch 2. The inner punch portion 21, together with a guide die 50 described later, prevents the axial deviation of the workpiece W.

[0026] The gas cylinder 4 is a device that applies a reaction force to the downward movement of the counter punch 3 caused by the pressing of the punch 2. The gas cylinder 4 is a device that applies a reaction force to the counter punch 3 by the pressure (back pressure) of a fluid. The gas cylinder 4 is equipped with a cylinder portion 41, a piston portion 42, a base portion 43, and a pressure transmission portion 44 from the bottom.

[0027] The cylinder portion 41 is filled with gas. The piston portion 42 is housed in the cylinder portion 41 so as to be movable in the vertical direction. Pressure is applied to the lower end surface of the piston portion 42. A predetermined reaction force (upward pressing force) is applied to the piston portion 42 by the pressure against the downward stroke.

[0028] The base portion 43 is a disk-shaped member fixed to the upper end surface of the piston portion 42. A plurality of cylinder portions 41 and piston portions 42 are arranged below the base portion 43. The upper end surface of the base portion 43 abuts against the lower unit (housing) 1a of the forging device 1, and upward movement is restricted. A through hole through which the knockout pin 72 is inserted is formed in the center of the base portion 43.

[0029] The pressure transmission part 44 is a member provided on the upper end surface of the base part 43 and transmits back pressure (reaction force). The pressure transmission part 44 extends in the vertical direction. The upper end part of the pressure transmission part 44 abuts against the pressure-receiving part 31 of the counter punch 3. The upward pressing force received by the piston part 42 is transmitted to the counter punch 3 via the base part 43 and the pressure transmission part 44.

[0030] The gas cylinder 4 constantly applies a reaction force to the counter punch 3 while the workpiece W is being formed. In other words, the workpiece W is formed with a reaction force (back pressure) being applied to the counter punch 3. This allows the workpiece W to be formed with a tooth profile that provides good firmness.

[0031] The forming die 5 is an annular die having a forming groove 5a formed on its inner peripheral surface. When the workpiece W is pressed into the inner peripheral side of the forming die 5, a shape corresponding to the forming groove 5a is formed on the outer peripheral surface of the workpiece W. The forming die 5 of the first embodiment is composed of multiple dies having the same vertical width, i.e., an inner die 51 and an outer die 52. The inner die 51 is an inner annular member having the forming groove 5a.

[0032] The outer die 52 is an annular member disposed on the outer periphery side of the inner die 51. The inner peripheral surface of the outer die 52 is formed to a shape that matches the outer peripheral surface of the inner die 51. The inner peripheral surface of the outer die 52 and the outer peripheral surface of the inner die 51 are in full contact with each other. The outer peripheral surface of the outer die 52 is formed in a tapered shape that becomes larger in diameter downward. In other words, the outer diameter of the forming die 5 becomes larger in the downward direction.

[0033] A guide die 50 is disposed above the forming die 5 coaxially with the forming die 5. The guide die 50 is composed of two dies, like the forming die 5. The guide die 50 is positioned (fixed) relative to the forming die 5. The guide die 50 guides the movement of the workpiece W. At the start of forming, the workpiece W is disposed inside the guide die 50. The punch 2 and the workpiece W enter the inside of the forming die 5 through the guide die 50.

[0034] The ring member 6 is an annular member arranged on the outer periphery of the forming die 5, and configured so that the pressing force with which the ring member 6 presses the forming die 5 changes depending on the vertical position of the ring member 6. The forming die 5 is pressed into the ring member 6. The ring member 6 can be called a press-fit ring. The inner peripheral surface of the ring member 6 is tapered to match the outer peripheral surface of the forming die 5. In other words, the inner diameter of the ring member 6 increases toward the bottom. The inner peripheral surface of the ring member 6 and the outer peripheral surface of the forming die 5 are in contact with each other. The ring member 6 and the forming die 5 are configured so that the pressing force of the ring member 6 changes depending on the vertical position of the ring member 6. The ring member 6 and the forming die 5 are configured so that the pressing force of the ring member 6 decreases as the ring member 6 moves upward.

[0035] The driving unit 7 is a device that moves the ring member 6 in the up-down direction. The driving unit 7 includes a driving source 71, a knockout pin 72, and a power transmission member 73. The driving source 71 is a device that drives the knockout pin. The driving source 71 includes, for example, a motor and a linear motion conversion member, and converts the rotational force of the motor into a moving force in the up-down direction and applies it to the knockout pin 72.

[0036] The knockout pin 72 is a member for removing the workpiece W from the forming die 5 after the forming is completed. The knockout pin 72 is a rod-shaped member (e.g., a cylindrical member) extending in the vertical direction, and moves in the vertical direction by the driving force of the driving source 71. The knockout pin 72 is disposed below the counter punch 3. When the knockout pin 72 moves upward, it abuts against the lower end surface of the counter punch 3, and then moves the counter punch 3 upward. The workpiece W after the forming is completed moves upward by the upward movement of the knockout pin 72 and the counter punch 3, and is pushed out above the guide die 50. At this time, the moving part 23 of the punch 2 also moves upward together with the movement of the knockout pin 72. The forging device 1 of the first embodiment is configured to push the workpiece W into the forming die 5 from above and to remove it from above.

[0037] The power transmission member 73 is a member that transmits the up and down movement (power) of the knockout pin 72 to the ring member 6. The power transmission member 73 moves up and down in conjunction with the up and down movement of the knockout pin 72. The power transmission member 73 includes a base portion 731 and a plurality of connection portions 732. The base portion 731 is a plate-like portion fixed to the knockout pin 72. The upper end portion of the knockout pin 72 is fixed to the center of the base portion 731.

[0038] The connection portion 732 is a rod-shaped member extending upward from the outer periphery of the base portion 731. The lower end of the connection portion 732 is fixed to the base portion 731, and the upper end is fixed to the ring member 6. In other words, the connection portion 732 connects the base portion 731 and the ring member 6. The knockout pin 72 and the ring member 6 are linked by the power transmission member 73. In other words, the knockout pin 72, the ring member 6, and the power transmission member 73 move up and down integrally.

[0039] The detection unit 8 is a device that detects the vertical position information of the punch 2. The detection unit 8 is, for example, a linear gauge (linear sensor) that measures the linear displacement of the punch 2. The detection unit 8 transmits the detection result to the control unit 9. The position of the workpiece W can be estimated from the position of the punch 2. As in the first embodiment, in the electric servo press, the control unit 9 grasps the position of the punch 2 by the linear gauge (detection unit 8).

[0040] The detection unit 8 may be a digital caliper. The position of the punch 2 is not limited to direct position information such as the detection result of a linear gauge, and may be calculated based on, for example, the rotational position of a motor, the load received by the punch 2, or the elapsed time since the punch 2 started to operate. In other words, the detection unit 8 may be, for example, a rotation angle sensor, a load sensor, or a timer function (time measurement function) of the control unit 9 as a means for detecting the position of the punch 2. It can also be said that the detection unit 8 detects the movement (amount of movement) of the punch 2.

[0041] The control unit 9 controls the drive unit 7 (drive source 71) based on the detection result of the detection unit 8. The control unit 9 is an electronic control unit (ECU) or a computer having a CPU, memory, etc. The control unit 9 is capable of communicating with the controlled object via wired or wireless communication. The control unit 9 controls the positions of the punch 2 and the knock-out pin 72. The punch 2 and the knock-out pin 72 can be controlled to move in conjunction with each other. The control unit 9 moves the knock-out pin 72 in synchronization with the movement of the punch 2, for example. In other words, the control unit 9 moves the ring member 6 in accordance with the movement of the punch 2.

[0042] (Forming of crowned gears) In the following description, the pressing force with which the ring member 6 presses the forming die 5 is referred to as the "ring pressing force." When forming a gear with a crowning (here, a helical gear), the control unit 9 controls the drive unit 7 so that the ring pressing force when the upper end or lower end of the workpiece W is located at a predetermined position P (see FIG. 3) in the vertical direction of the forming die 5 is greater than the ring pressing force when the middle part of the workpiece W is located at the predetermined position P of the forming die 5. The forming groove 5a is formed into a tooth shape.

[0043] As shown in Fig. 2, the forming groove 5a in this example has a groove width (length in a direction perpendicular to the extension direction of the groove) that becomes smaller toward the radially outer side (bottom surface). Also, as shown in Fig. 3, the forming groove 5a of the forming die 5 is provided with an approach portion 5a1 and a land portion 5a2. The approach portion 5a1 constitutes the upper end portion of the forming groove 5a and is a portion that is inclined so as to be positioned radially inward toward the lower portion. The approach portion 5a1 allows the workpiece W to be gradually deformed while being placed into the forming die 5.

[0044] The land portion 5a2 is a portion of the molding groove 5a that is formed below the approach portion 5a1. The land portion 5a2 extends downward at the same position as the radially innermost position of the approach portion 5a1. In other words, the land portion 5a2 is a portion that extends downward so as to maintain the maximum radially inward protruding height (maximum groove depth) of the approach portion 5a1. The predetermined position P in the first embodiment corresponds to the upper end of the land portion 5a2 (or the lower end of the approach portion 5a1).

[0045] The forming groove 5a is formed so that the workpiece W pressed downward enters the approach portion 5a1 and undergoes elastic deformation, and then undergoes plastic deformation when it reaches the land portion 5a2. That is, when the workpiece W is located at the predetermined position P, the shape of the portion of the workpiece W facing the predetermined position P is determined. When the workpiece W reaches the land portion 5a2, deformation in the plastic region of the workpiece W occurs. The outer diameter of the workpiece W is greater than the minimum inner diameter of the forming die 5 (forming groove 5a) and less than the maximum inner diameter (minimum inner diameter of the forming die 5<outer diameter of the workpiece W<maximum inner diameter of the forming die 5). During forming (at least after the workpiece W enters the land portion 5a2), the workpiece W and the bottom surface of the forming groove 5a are in contact with each other. That is, no gap is generated between the bottom surface of the forming groove 5a and the workpiece W during forming. The outer diameter of the workpiece W is maintained less than the maximum inner diameter of the forming die 5 by the guide die 50. Even if the outer diameter of the workpiece W is equal to or greater than the maximum inner diameter of the forming die 5, forming according to this embodiment is possible.

[0046] The control unit 9 controls the position of the ring member 6 so that the ring pressing force becomes relatively large when the lower end of the workpiece W is located at a predetermined position P of the forming groove 5a. The control unit 9 moves the ring member 6 slightly downward when forming starts. As shown in FIG. 4, when the ring member 6 moves downward, the tapered surface acts, and the inner diameter of the ring member 6 corresponding to the upper end of the forming die 5 becomes smaller. As a result, the outer peripheral surface of the forming die 5 is pressed against the ring member 6, and the diameter of the forming die 5 becomes smaller. Forming starts in this state, the punch 2 descends, and the workpiece W enters the approach portion 5a1 and reaches the land portion 5a2 with a smaller diameter, and the lower end of the workpiece W is formed.

[0047] Then, when the detector 8 detects that the bottom end of the workpiece W is about to pass the predetermined position P, the controller 9 moves the ring member 6 upward, and increases the inner diameter of the ring member 6 that corresponds to the top end of the forming die 5 (see FIG. 4). This reduces the ring pressing force, and increases the diameter of the forming die 5. In this state, the middle part of the workpiece W (a part excluding the bottom and top ends) enters the predetermined position P. The middle part of the workpiece W is formed by the land portion 5a2, which has a larger diameter than when the bottom end is formed.

[0048] When the middle part of the work W passes the predetermined position P and the upper end part of the work W is about to enter the predetermined position P, the control unit 9 moves the ring member 6 downward and increases the ring pressing force again. As a result, the upper end part of the work W is formed by the small diameter forming die 5, just like the lower end part.

[0049] The amount of downward movement of the ring member 6 is the same when forming the upper end and the lower end of the workpiece W. When the upper end of the workpiece W is located at the predetermined position P, the diameter of the forming die 5 becomes smaller overall, and therefore the diameter of the forming die 5 corresponding to the middle and lower end of the workpiece W that have passed the predetermined position P also becomes smaller. However, the change in the diameter of the forming die 5 due to the movement of the ring member 6 is a change in the elastic region (a change on the order of several tens of μm). Therefore, even if the middle and lower end of the workpiece W are deformed when the upper end of the workpiece W is formed, it is an elastic deformation and does not affect the shape of the workpiece W after forming is completed.

[0050] In this way, the control unit 9 increases the ring pressing force at the upper and lower ends of the workpiece W to reduce the diameter of the forming die 5, and decreases the ring pressing force at the middle part of the workpiece W to increase the diameter of the forming die 5. When the diameter of the forming die 5 becomes smaller, the shape of the forming groove 5a also becomes smaller in a similar manner. In other words, the smaller the diameter of the forming die 5, the smaller the groove width of the forming groove 5a. Therefore, according to the above control, the tooth width of the formed workpiece W is relatively small at the upper and lower ends and relatively large at the middle part. For example, as shown in Figures 5 and 6, the tooth profile and crowning are formed in the workpiece W after forming is completed by one punch.

[0051] In the first embodiment, the movement of the punch 2 and the movement of the ring member 6 (knockout pin 72) are set to be linked, and forming can be performed without stopping the punch 2. For example, the control unit 9 positions the punch 2 and the ring member 6 at a specified position at the start of forming, gradually moves the ring member 6 upward as the middle part of the workpiece W approaches the predetermined position P, and gradually moves the ring member 6 downward as the bottom end part of the workpiece W approaches the predetermined position P. It is also possible to change the position of the ring member 6 after stopping the punch 2.

[0052] (Effects of the first embodiment) According to the first embodiment, the ring member 6 presses the forming die 5 with a ring pressing force according to the position, thereby elastically deforming the forming die 5 and changing its inner diameter. The larger the ring pressing force, the more the forming die 5 is tightened radially inward, and the smaller its inner diameter. In other words, it is possible to change the radial dimension of the tooth profile during forming. The smaller the diameter of the forming die 5, the smaller the shape (groove width, etc.) of the forming groove 5a becomes similarly. As a result, when forming a gear with a crowning, for example, the control unit 9 changes the ring pressing force according to the position of the punch 2 to change the inner diameter of the forming die 5, making it possible to form a gear with a crowning with one punch (without forming an intermediate cylindrical gear).

[0053] Furthermore, with this configuration, the formed shape can be finely adjusted by adjusting the reaction force and / or the ring pressing force, so there is no need to replace the device even if there is a change in frictional resistance, etc. For example, the control unit 9 adjusts the position of the ring member 6, i.e., the ring pressing force, so that the tooth width, dimensions, etc. formed on the workpiece W can be adjusted.

[0054] In addition, by adjusting the pressure (back pressure) of the gas cylinder 4, the tooth width formed on the workpiece W can be adjusted. For example, the higher the pressure of the gas cylinder 4, the harder it is for the punch 2 to move downward, and the workpiece W is pinched between the punches with a strong force. As a result, the radial deformation of the workpiece W is promoted, and the workpiece W (teeth) is pushed toward the bottom side of the forming groove 5a. This makes it possible to adjust the formed shape.

[0055] Thus, according to the first embodiment, the total man-hours can be reduced, and the formed shape can be finely adjusted without replacing the equipment. Furthermore, by synchronizing the position control of the ring member 6 with the movement of the punch 2, continuous forming control is possible. The configuration of the first embodiment is particularly effective in manufacturing crowned gears. The pressure of the gas cylinder 4 may be adjusted, for example, by replacing the gas cylinder 4 or by pressure control by the control unit 9 (see the second embodiment described later).

[0056] In addition, the position of the ring member 6 can be changed by utilizing the configuration of the knockout pin 72, which allows for effective use of parts. After molding is completed, when the knockout pin 72 rises and the workpiece W is removed, the ring member 6 also rises, reducing the ring pressing force (for example, the ring member 6 is released from the press-fit into the molding die 5), making it easier to remove the workpiece W.

[0057] In this way, when the workpiece W is removed from the forming die 5, that is, before or while the workpiece W is being removed from the forming die 5, the control unit 9 controls the drive unit 7 to make the ring pressing force smaller than the ring pressing force (minimum value during molding) when the workpiece W is formed. In the configuration of the first embodiment in which the knockout pin 72 is used as a part of the drive unit 7, when the workpiece W is removed, the ring pressing force decreases as the knockout pin 72 rises. On the other hand, even if the drive unit 7 is configured independent of the knockout pin 72, the control unit 9 may control the drive unit 7 so that the ring pressing force becomes smaller when the workpiece W is removed. As a result, the inner diameter of the forming die 5 becomes larger than when the workpiece W was formed, the knockout load is reduced, and the workpiece W is easily removed as described above. According to this configuration, unnecessary force is prevented from being applied to the tooth surface of the workpiece W after the formation is completed, and the dimensional accuracy of the product can be maintained better. Note that the control unit 9 may set the ring pressing force to, for example, the minimum value in the configuration when the workpiece W is removed.

[0058] <Second embodiment> The forging device 100 of the second embodiment differs from the first embodiment in that it does not have a ring member 6 and a power transmission member 73, and the control unit 9 is configured to be able to adjust the pressure (back pressure) of the gas cylinder 4. Therefore, only the different parts will be described, and the description of the other parts will be omitted. In the description of the second embodiment, the description and drawings of the first embodiment can be referred to.

[0059] As shown in Fig. 7, the forging device 100 includes a punch 2, a counter punch 3, a gas cylinder (corresponding to a "reaction force applying device") 4, a forming die 5, a detection unit 8, and a control unit 9. The control unit 9 controls the reaction force (back pressure) applied by the gas cylinder 4 based on the detection result of the detection unit 8. The control unit 9 of the second embodiment changes the reaction force in accordance with (in synchronization with) the movement of the punch 2.

[0060] Taking the manufacture of a crowned gear as an example, the control unit 9 controls the gas cylinder 4 so that the reaction force when the upper or lower end of the workpiece W is located at a predetermined position P in the vertical direction of the forming die 5 is smaller than the reaction force when the middle part of the workpiece W is located at the predetermined position P of the forming die 5.

[0061] The gas cylinder 4 is provided with a pressure regulator (e.g., a solenoid valve) 45 that adjusts the pressure inside the cylinder portion 41 as a means for adjusting the reaction force. The control portion 9 controls the pressure regulator 45 to control the reaction force. During forming, a reaction force (back pressure) from the gas cylinder 4 is constantly applied to the counter punch 3, as in the first embodiment. This allows a tooth profile with good firmness to be formed in the workpiece W. In the second embodiment, there is no pressure transmission portion 44, and the base portion 43 directly presses the counter punch 3.

[0062] The gas cylinder 4 may be configured to include, for example, a plurality of cylinders with different pressures and a cylinder switch. The cylinder switch is an electromagnetic valve that switches the connected cylinder. In this case, the control unit 9 controls the cylinder switch to adjust the output pressure of the gas cylinder 4.

[0063] (Effects of the second embodiment) According to the second embodiment, by changing the reaction force according to the position of the punch 2, the degree of deformation of the workpiece W can be changed, similar to the adjustment of the gas cylinder 4 in the first embodiment. In other words, the larger the reaction force, the larger the clamping force in the vertical direction on the workpiece W, and the larger the amount of radial outward expansion of the workpiece W. As a result, when forming a gear with a crowning, for example, the control unit 9 can change the reaction force according to the position of the punch 2, making it possible to form a gear with a crowning with one punch (without forming an intermediate cylindrical gear). Furthermore, according to this configuration, since the formed shape can be finely adjusted by adjusting the reaction force, there is no need to replace the device even if a change in frictional resistance occurs.

[0064] Thus, according to the second embodiment, the total number of steps can be reduced, and the formed shape can be finely adjusted without replacing the equipment. In addition, continuous forming control is possible by synchronizing the pressure control of the gas cylinder 4 with the movement of the punch 2. The configuration of the second embodiment is also particularly effective in manufacturing crowned gears.

[0065] <Common manufacturing method> A common manufacturing method for manufacturing the above-mentioned crowned gear will be described. The manufacturing method of this embodiment includes a drawing process in which a workpiece W having an outer diameter larger than the minimum inner diameter of the forming die 5 is pressed into the forming die 5. In the drawing process, the punch 2 presses the workpiece W into the forming die 5 while a reaction force is applied to the counter punch by a reaction force applying device (for example, a gas cylinder 4), and compresses and deforms the workpiece W. In other words, the drawing process (compression process) is performed while a reaction force (entry resistance) due to fluid pressure is applied to the workpiece W. This assists the flow of the tooth tips in the formation of the tooth profile, and the pressing force with which the workpiece W (tooth tips) presses the bottom surface of the forming groove 5a during formation increases. In other words, a tooth profile with good thickness is formed in the workpiece W.

[0066] <Third embodiment> The forging device 100A of the third embodiment differs from the second embodiment in that the control unit 9 does not adjust the reaction force, but the frictional force when the moving member (counter punch or first knockout pin 721) moves is configured to change depending on the position of the moving member. Therefore, only the different parts will be described, and the description of the other parts will be omitted. In the description of the third embodiment, the description and drawings of the first and second embodiments can be referred to.

[0067] As shown in FIG. 8, the forging device 100A includes a punch 2, a counter punch 3, a forming die 5, a first knockout pin (corresponding to the “interlocking member” and the “moving member”) 721, a second knockout pin 722, a collar member 74, a detection unit 8, and a control unit 9.

[0068] The first knockout pin 721 is a rod-shaped interlocking member that moves downward in conjunction with the downward movement of the counter punch 3. The first knockout pin 721 is disposed below the counter punch 3. In the initial position, the upper end surface of the first knockout pin 721 abuts against the lower end surface of the counter punch 3. A detailed configuration will be described later.

[0069] The second knockout pin 722 is a rod-shaped member disposed below the first knockout pin 721. The second knockout pin 722 is spaced apart from the first knockout pin 721 and disposed so as not to come into contact with the first knockout pin 721 even when the counter punch 3 is located at its lowest point (i.e., when forming is completed) (or so as to come into contact with the first knockout pin 721 when the counter punch 3 is located at its lowest point).

[0070] The second knockout pin 722 moves upward integrally with the first knockout pin 721 while in contact with the first knockout pin 721 by operation of the driving source 71. In other words, the first knockout pin 721 and the second knockout pin function as one knockout pin 72 and push the counter punch 3 upward. The knockout pin is also called a knockout rod.

[0071] Collar member 74 is disposed around first knockout pin 721 and generates a frictional force against the movement of first knockout pin 721. Collar member 74 is formed in an annular shape and configured so that first knockout pin 721 is inserted into a central through-hole 741. Collar member 74 holds first knockout pin 721 by frictional force so that first knockout pin 721 is movable up and down to prevent gravity from moving downward.

[0072] (Details of the first knockout pin and collar part) The first knockout pin 721 and the collar member 74 are configured such that the frictional force between the first knockout pin 721 and the collar member 74 changes depending on the position of the first knockout pin 721.

[0073] The first knockout pin 721 has a first protrusion 721a protruding outward. The first protrusion 721a is formed in a ring shape protruding around the entire circumference at a part of the axial direction of the first knockout pin 721. As shown in Fig. 9, the first protrusion 721a is formed so that the outer diameter of the first knockout pin 721 gradually increases from the upper end to the apex and gradually decreases from the apex to the lower end.

[0074] The collar member 74 has a second protrusion 74a protruding toward the inner periphery. The first knockout pin 721 and the collar member 74 are configured such that the frictional force between the first knockout pin 721 and the collar member 74 is increased by the first protrusion 721a and the second protrusion 74a coming into contact with each other.

[0075] The second protrusion 74a is formed in a ring shape protruding over the entire circumference at a portion of the axial direction of the collar member 74. The second protrusion 74a is formed so that the inner diameter of the collar member 74 gradually decreases from the upper end to the apex and gradually increases from the apex to the lower end. The second protrusion 74a in this example is configured to abut only against the first protrusion 721a. In other words, the minimum diameter of the second protrusion 74a is larger than the outer diameter of the first knockout pin 721 excluding the first protrusion 721a.

[0076] The first protrusion 721a is configured to come into contact with the inner circumferential surface of the collar member 74. That is, in this example, the maximum diameter of the first protrusion 721a is larger than the maximum inner diameter of the collar member 74. Therefore, the first knockout pin 721 is press-fitted into the collar member 74. In the initial position, the first protrusion 721a comes into contact with the inner circumferential surface of the collar member 74 above the second protrusion 74a. The first knockout pin 721 in the initial position is positioned by the frictional force between the first protrusion 721a and the collar member 74.

[0077] When forging is started and the counter punch 3 moves downward, the first knockout pin 721 is pressed by the counter punch 3 and moves downward. When the first convex portion 721a moves downward, it comes into contact with the second convex portion 74a. As the first convex portion 721a moves downward, the diameter of the through hole 741 becomes smaller due to the second convex portion 74a. That is, the press-fit allowance becomes larger in the portion where the second convex portion 74a is formed. As a result, the passing resistance (friction force) of the first convex portion 721a attempting to pass through the second convex portion 74a becomes larger, and the reaction force against the downward movement of the counter punch 3 becomes larger.

[0078] When the apex of the first convex portion 721a and the apex of the second convex portion 74a come into contact with each other, the frictional force (reaction force) is maximized. When the first convex portion 721a moves downward from the apex of the second convex portion 74a, the frictional force becomes smaller. Since the second convex portion 74a is formed with a gentle gradient, the frictional force changes gradually. In other words, when the first convex portion 721a comes into contact with the second convex portion 74a, the frictional force gradually increases as the first convex portion 721a moves downward, and the frictional force gradually decreases after passing the apex of the second convex portion 74a.

[0079] In this way, according to the mountain-shaped second convex portion 74a, the press-fit allowance (frictional force during passage) is maximum at the apex of the second convex portion 74a and gradually decreases toward the upper end and the lower end. In other words, the first knockout pin 721 and the collar member 74 of the third embodiment are configured so that the frictional force when the upper end or the lower end of the workpiece W is located at a predetermined position P in the vertical direction of the forming die 5 is smaller than the frictional force when the middle part of the workpiece W is located at the predetermined position P of the forming die 5. Also, the forming groove 5a is formed in a tooth shape.

[0080] (Effects of the third embodiment) According to the third embodiment, the reaction force can be changed by changing the friction force between the first knockout pin 721 and the collar member 74 depending on the position of the counter punch 3. This makes it possible to change the degree of deformation of the workpiece W, as in the second embodiment. In other words, the greater the reaction force (friction force), the greater the amount of radial outward bulging of the workpiece. This makes it possible, for example, to form a gear with a crowning with a single punch (without forming an intermediate cylindrical gear) without special control.

[0081] Also, it is possible to finely adjust the frictional force by changing the shape and surface roughness of the first convex portion 721a and / or the second convex portion 74a (for example, by filing, etc.). In other words, the back pressure (reaction force) can be adjusted by the press-fitting margin between the first knockout pin 721 and the collar member 74 and / or the surface roughness of the contact surface between them. Also, since frictional force is constantly generated by the press-fitting action during the downward movement of the counter punch 3, a tooth profile with good firmness is formed in the workpiece W.

[0082] (Modification of the third embodiment) The first protrusion 721a may be formed to abut only against the second protrusion 74a. In this case, the first knockout pin 721 and the collar member 74 are engaged with each other by the abutment between the first protrusion 721a and the second protrusion 74a. That is, in this case, the first protrusion 721a and the second protrusion 74a are in abutment with each other from the initial position. Then, when the apex position of the first protrusion 721a is lower than the lower end of the second protrusion 74a, the frictional force disappears and the first knockout pin 721 and the second knockout pin 722 abut with each other. Even with this configuration, a gear with a crowning can be manufactured.

[0083] Furthermore, the minimum value of the inner diameter of the second convex portion 74a may be smaller than the minimum diameter of the first knockout pin 721. That is, in the initial position, the second convex portion 74a may be in contact with the outer circumferential surface of the first knockout pin 721. For example, in this case, the maximum diameter of the first convex portion 721a may be smaller than the maximum value of the inner diameter of the collar member 74. That is, the design may be such that a frictional force is generated by at least one of the first convex portion 721a and the second convex portion 74a even in a state in which the first convex portion 721a and the second convex portion 74a are not in contact with each other.

[0084] 8, a reaction force applying device (for example, a gas cylinder 4) may be disposed below the first knockout pin 721. In this case, a back pressure from the reaction force applying device and a frictional force between the first knockout pin 721 and the collar member 74 are applied as reaction forces to the counter punch 3. The reaction force applying device may be configured to be capable of controlling the reaction force.

[0085] Also, the first convex portion 721a may be provided on the counter punch 3 (corresponding to the "moving member"). In this case, the collar member 74 having the second convex portion 74a is disposed around the counter punch 3. This also produces the same effect as above. In this manner, the collar member 74 is disposed around the counter punch 3 or the interlocking member (first knockout pin 721) that moves downward in conjunction with the downward movement of the counter punch 3. In other words, the moving member, which is the first knockout pin 721 (interlocking member) or the counter punch 3, is disposed inside the collar member 74. The interlocking member is not limited to the first knockout pin 721, and may be another member.

[0086] <Other> The present invention is not limited to the above embodiment. For example, the formed product may be something other than a crowned gear. That is, the forging device 1, 100 can form things other than a crowned gear. In addition, the control of the ring pressing force is not limited to the control of switching to the upper end, middle part, and lower end of the work W, but may be set according to the forming target. In addition, the width of the upper end and the lower end of the work W can be set according to the design of the crowning. In addition, the reaction force applying device that applies a reaction force to the counter punch 3 may be a back pressure applying device (for example, a gas cylinder 4 or a stroke simulator) that outputs the pressure of a fluid as a reaction force, or may be something else.

[0087] In addition, the land portion 5a2 of the forming groove 5a may be configured so that the portion below the upper end is located radially outward from the upper end (the groove is shallower). In other words, only the upper end of the land portion 5a2 may be located at the most radially inner side (the groove is deeper). In other words, the portion of the forming groove 5a including the predetermined position P has a convex shape toward the center of the forming die 5. This makes it possible to prevent the forming groove 5a from pressing the middle part and the lower end of the already formed workpiece W when the diameter of the forming die 5 becomes smaller during forming of the upper end of the workpiece W. In addition, the groove width of the forming groove 5a does not have to become smaller toward the radially outer side as shown in FIG. 2, and may be, for example, a constant width.

[0088] Furthermore, the ring member 6 may be a member configured such that the ring pressing force can be controlled by the control unit 9, such as a vice with the forming die 5 disposed inside. In this case, the drive unit 7 is a device that rotates the handle of the vice. That is, in the present invention, the ring member 6 is a member configured such that the pressing force (ring pressing force) that presses the forming die 5 changes depending on the state, and the drive unit 7 is a device that changes the state of the ring member 6. The state is, for example, the vertical position of the ring member 6 or the rotational position of the handle, and can also be said to be the state of the part where the ring member 6 applies the pressing force to the forming die 5 (the value of the minimum inner diameter).

[0089] Furthermore, the workpiece W is not limited to being annular, and may be a shafted member (which becomes a shafted gear after molding) in which a shaft-shaped portion is provided on the gear portion, as shown in Fig. 8, for example. In this case, as shown in Fig. 9, for example, the lower end of the punch 2 and the upper end of the counter punch 3 are formed into a concave shape with a recessed center. The shaft-shaped portion of the workpiece W is placed within the recess of each punch. Even with such a configuration, the same effects as the above embodiment can be achieved.

[0090] As a concept of the present invention, it can be said that the forging device 1 is equipped with a pressing force adjusting means (ring member 6, drive unit 7, and control unit 9) that adjusts the pressing force (corresponding to the ring pressing force) applied to the outer peripheral surface of the forming die 5 to change the inner diameter of the forming die 5. As in the first embodiment, the pressing force adjusting means changes the variable pressing force in accordance with the movement of the punch 2. In addition, the pressing force adjusting means makes the variable pressing force when the upper end or lower end of the workpiece W is located at a predetermined position P in the vertical direction of the forming die 5 larger than the variable pressing force when the middle part of the workpiece W is located at the predetermined position P of the forming die 5.

[0091] Furthermore, the pressing force adjusting means makes the variable pressing force smaller when removing the workpiece W from the forming die 5 than when the workpiece W was formed. The gear manufacturing method includes a removal step of removing the workpiece W from the forming die 5 after the forming of the workpiece W is completed. In this removal step, the pressing force adjusting means makes the pressing force (hereinafter referred to as the variable pressing force) applied to the outer circumferential surface of the forming die 5 smaller than when the workpiece W was formed. This increases the inner diameter (inner dimension, passage cross-sectional area) of the forming die 5, and allows the workpiece W to be removed with high precision after forming is completed. [Explanation of symbols]

[0092] 1, 100, 100A... forging device, 2... punch, 3... counter punch (movable member), 4... gas cylinder (reaction force applying device), 5... forming die, 5a... forming groove, 6... ring member, 7... drive unit, 721... first knockout pin (interlocking member, movable member), 73... collar member, 8... detection unit, 9... control unit, W... work.

Claims

1. A punch that presses the workpiece downward by moving downward; A counter punch is disposed below the punch and on which the workpiece is placed; a reaction force applying device that applies a reaction force to a downward movement of the counter punch caused by the pressing of the punch; An annular forming die having a forming groove formed on an inner peripheral surface thereof; an annular ring member that is disposed on the outer periphery of the forming die and is configured so that a pressing force that presses the forming die changes depending on a state; A drive unit that changes the state of the ring member; a detection unit for detecting vertical position information of the punch; A control unit that controls the drive unit based on a detection result of the detection unit; A forging device comprising:

2. The forging device according to claim 1 , wherein the control unit moves the ring member in synchronization with the movement of the punch.

3. The forming groove is formed into a tooth shape, The control unit is 3. The forging device according to claim 1, wherein the driving unit is controlled so that the pressing force when the upper end or lower end of the workpiece is located at a predetermined position in the vertical direction of the forming die is greater than the pressing force when the middle portion of the workpiece is located at the predetermined position of the forming die.

4. the ring member and the forming die are configured so that the pressing force changes depending on the vertical position of the ring member, The forging device according to any one of claims 1 to 3, wherein the drive unit moves the ring member in a vertical direction.

5. The drive unit is A knockout pin for removing the workpiece from the forming die after forming is completed; A drive source that drives the knockout pin up and down; a power transmission member that transmits the up and down movement of the knockout pin to the ring member; The forging apparatus of claim 4 .

6. 6. The forging apparatus of claim 5, wherein the ring member and the forming die are configured such that the pressing force decreases as the ring member moves upward.

7. The forging device according to any one of claims 1 to 6, wherein the control unit controls the drive unit to make the pressing force smaller than the pressing force when the workpiece is formed when the workpiece is removed from the forming die.

8. The forging device according to any one of claims 1 to 7, wherein the reaction force applying device constantly applies the reaction force to the counter punch during forming of the workpiece.

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