Method of stamping and method of manufacturing a mechanical device

Abstract

Implement a stamping method that can improve the machining accuracy of workpieces. A method uses a stamping machine (1) equipped with a frame (2) having a reference axis C, a lower die (6) supported by the frame (2), an upper die (7) supported by the frame (2) so as to be able to move closer to and farther from the lower die (6) in the axial direction of the reference axis C, and a hydraulic cylinder (5) that generates a force in the direction of bringing the upper die (7) closer to the lower die (6). With a workpiece (11) having a rotationally symmetric shape centered on the workpiece central axis arranged between the lower die (6) and the upper die (7), the upper die (7) is brought closer to the lower die (6) by the hydraulic cylinder (5), thereby performing stamping on the workpiece (11) between the lower die (6) and the upper die (7). In this method, the shapes of the frame (2), the lower die (6), and the upper die (7) are each set to a rotationally symmetric shape centered on the reference axis C, and the above stamping is performed on the workpiece (11) with the workpiece central axis aligned with the reference axis C.

Description

Technical Field

[0001] The present invention relates to a method for performing stamping on a workpiece as an object to be processed using a stamping machine and a method for manufacturing a mechanical device. Background Art

[0002] By introducing a stamping process into the manufacturing process of metal parts that make up various mechanical devices such as automobiles or industrial machinery, the manufacturing efficiency of the metal parts is improved (for example, refer to Japanese Patent Laid-Open No. 2008-296241 (Patent Document 1)). In addition, there are multiple types in stamping, such as shearing, deep drawing, bending, and forging.

[0003] A stamping machine for stamping includes a frame having a reference axis, a first die, and a second die. The first die is supported by the frame. The second die is supported by the frame so as to be able to move closer to and farther from the first die with respect to the axial direction of the reference axis. And, by bringing the second die closer to the first die in a state where the workpiece is disposed between the first die and the second die, stamping is performed on the workpiece between the first die and the second die.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Laid-Open No. 2008-296241 Summary of the Invention

[0007] In stamping using a stamping machine, as a method for improving the processing accuracy of a workpiece, methods such as manufacturing the first die and the second die with high precision and improving the coaxiality of the first die and the second die with respect to the reference axis of the frame in the assembled state of the stamping machine can be considered.

[0008] However, even if such methods are adopted, during stamping, due to the processing reaction forces applied to the first die and the second die from the workpiece, elastic deformation will occur in the first die, the second die, and the frame. And, if a relative inclination occurs between the first die and the second die due to such elastic deformation, there are problems such as a decrease in the processing accuracy of the workpiece and a large force being required to bring the second die closer to the first die, that is, a large energy loss.

[0009] In view of the above circumstances, an object of the present invention is to achieve a stamping method that can improve the processing accuracy of a workpiece and suppress energy loss to a small level.

[0010] The first aspect of the stamping method of the present invention uses a stamping machine including a frame having a reference axis, a first die, a second die, and a hydraulic cylinder. With a workpiece having a workpiece central axis and a rotationally symmetric shape centered on the workpiece central axis disposed between the first die and the second die, the second die is pushed toward the first die by the hydraulic cylinder to bring the second die closer to the first die, thereby performing stamping on the workpiece between the first die and the second die. The first die is supported by the frame, the second die is supported by the frame so as to be able to move closer to and farther from the first die in the axial direction of the reference axis, and the hydraulic cylinder generates a force in the direction of bringing the second die closer to the first die.

[0011] In the first aspect, the shapes of the frame, the first die, and the second die are each set to a rotationally symmetric shape centered on the reference axis. And, with the workpiece central axis aligned with the reference axis, the stamping is performed on the workpiece. In addition, rotational symmetry is one of the symmetries that characterize a figure (shape), and it means that when a spatial figure is rotated about an axis and coincides with the original figure at every 2π / n (n: a positive integer of 2 or more) angles, the figure has n-fold rotational symmetry (n-fold symmetry). In the present invention, in the case of n = 1 (since it is obvious that it overlaps with itself after a 360° rotation and cannot be said to have symmetry), it is not called rotational symmetry. In this specification and the claims, there are cases where a shape having rotational symmetry is expressed as a rotationally symmetric shape, and there are cases where a shape not having rotational symmetry is expressed as a non-rotationally symmetric shape.

[0012] In one aspect of the first aspect of the stamping method of the present invention, the frame has a first frame portion that supports the first die, a second frame portion that supports the second die, and a plurality of column portions that connect the first frame portion and the second frame portion. In this case, for example, when the number of rotational symmetries related to the shape of the workpiece is n (n: a positive integer of 2 or more), the number of the column portions is set to n×2 k (k: 0 or a positive integer), and the column portions are arranged at equal intervals in the circumferential direction centered on the reference axis.

[0013] A second aspect of the stamping method of the present invention uses a stamping machine including a frame having a reference axis, a first die, a second die, and a hydraulic cylinder. With a workpiece having a non-rotationally symmetric shape when viewed axially from the reference axis disposed between the first die and the second die, the second die is pushed toward the first die by the hydraulic cylinder to bring the second die closer to the first die, thereby performing stamping on the workpiece between the first die and the second die. The first die is supported by the frame, the second die is supported by the frame so as to be movable closer to and farther from the first die axially with respect to the reference axis, and the hydraulic cylinder generates a force in a direction to bring the second die closer to the first die. The second aspect includes a radial positioning step and a stamping step. In the radial positioning step, a test is performed to obtain a relationship between a radial position, which is the radial position of the first die and the second die centered on the reference axis when performing stamping on the workpiece, and a relative inclination amount, which is the relative inclination amount between the first die and the second die generated when performing stamping on the workpiece, and one radial position at which the inclination amount becomes equal to or less than a specified value is determined using this relationship. In the stamping step, stamping is performed on the workpiece with the first die and the second die disposed at one radial position determined in the radial positioning step.

[0014] A third aspect of the stamping method of the present invention uses a stamping machine including a frame having a reference axis, a first die, a second die, and a link mechanism. With a workpiece disposed between the first die and the second die, the second die is pushed toward the first die by the link mechanism to bring the second die closer to the first die, thereby performing stamping on the workpiece between the first die and the second die. The first die is supported by the frame, and the second die is supported by the frame so as to be movable closer to and farther from the first die axially with respect to the reference axis.

[0015] Here, the link mechanism includes: a drive source; a first link member that is rotationally driven by the drive source; and a second link member that rotatably supports one end at a portion of the first link member radially offset from the rotational center axis of the first link member and rotatably supports the other end at the second die.

[0016] The third aspect includes a radial positioning step and a stamping step.

[0017] In the above-described radial positioning process, a test is conducted to obtain the relationship between the radial position and the relative inclination amount. The radial position is the radial position of the first die and the second die centered on the reference axis when the above workpiece is subjected to the above stamping process, and the relative inclination amount is the relative inclination amount between the first die and the second die generated when the above workpiece is subjected to the above stamping process. Using this relationship, one of the radial positions where the inclination amount becomes equal to or less than a specified value is determined. In the above stamping process, the above workpiece is subjected to the above stamping process in a state where the first die and the second die are arranged at one of the radial positions determined in the above radial positioning process.

[0018] In the second and third aspects of the stamping method of the present invention, for example, when conducting the above test, a laser displacement meter can be used to measure the inclination amount.

[0019] The mechanical device that is the object of the manufacturing method of the present invention includes a metal component. The manufacturing method of the mechanical device of the present invention includes a process of implementing the stamping method of the present invention in the manufacturing process of the above metal component.

[0020] Advantages of the Invention

[0021] According to the present invention, it is possible to improve the machining accuracy for workpieces and suppress small energy losses. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a perspective view schematically showing a punching machine according to the first example of the embodiment.

[0023] Figure 2 is a front view schematically showing a punching machine according to the first example of the embodiment.

[0024] Figure 3 is a top view schematically showing a punching machine according to the first example of the embodiment.

[0025] Figure 4 in Figure 4 (A) to Figure 4 (D) are cross-sectional views schematically showing four examples of the types of stamping processes of the lower die, upper die, and workpiece.

[0026] Figure 5 is a perspective view schematically showing a punching machine according to the second example of the embodiment.

[0027] Figure 6 in Figure 6 (A) to Figure 6(C) is a plan view showing three examples of the arrangement structure of the column portions constituting the frame in the case where the workpiece has a three-fold symmetric shape centered on its own central axis, which is the second example of the embodiment.

[0028] Figure 7 In Figure 7 (A) to Figure 7 (C) is a plan view showing three examples of the arrangement structure of the column portions constituting the frame in the case where the workpiece has a five-fold symmetric shape centered on its own central axis, which is the second example of the embodiment.

[0029] Figure 8 It is an enlarged view corresponding to part A of Figure 2 which is the third example of the embodiment.

[0030] Figure 9 It is a line graph showing the relationship between the radial offset amount (horizontal axis) of the central axes of the lower die and the upper die with respect to the reference axis and the inclination amount (vertical axis) of the central axis of the lower die and the central axis of the upper die during stamping.

[0031] Figure 10 It is the same figure as Figure 8 which is related to the fourth example of the embodiment.

[0032] Figure 11 It is a front view schematically showing a punching machine according to the fifth example of the embodiment.

[0033] Figure 12 It is Figure 11 a sectional view taken along line B-B of DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] [First Example of the Embodiment]

[0035] The first example of the embodiment of the present invention will be described using Figures 1 to 4 .

[0036] In this example, a hydraulic punching machine 1 is used in the manufacturing process of metal parts constituting various mechanical devices such as automobiles and industrial machines to perform stamping on a workpiece 11 (refer to Figure 2 , 4 ) which is an initial raw material or an intermediate raw material of the metal part. In particular, in this example, the workpiece 11 has a workpiece central axis as its own central axis and a rotationally symmetric shape centered on the workpiece central axis in each state before and after being stamped.

[0037] The punching machine 1 includes a reference axis C in the vertical direction that serves as a punching center, a frame 2, a bolster 3, a slide block 4, a hydraulic cylinder 5, a lower die 6 as the first die, and an upper die 7 as the second die.

[0038] The frame 2 includes a lower frame portion 8 as a first frame portion, an upper frame portion 9 as a second frame portion disposed above the lower frame portion 8, and a plurality of column portions 10 connecting the lower frame portion 8 and the upper frame portion 9. The column portions 10 extend in the vertical direction respectively, with their lower ends joined to the lower frame portion 8 and their upper ends joined to the upper frame portion 9.

[0039] The frame 2 has a rotationally symmetric shape centered on the reference axis C. In particular, in this example, it has a four-fold symmetric shape centered on the reference axis C. Therefore, in this example, the lower frame portion 8 and the upper frame portion 9 each have a rectangular parallelepiped shape with a top view shape ( Figure 3 the shape observed from above as shown) being a square. The phase of the top view shape (square) of the lower frame portion 8 and the top view shape (square) of the upper frame portion 9 in the circumferential direction (at the vertices where the sides intersect each other) centered on the reference axis C is the same. The number of the column portions 10 is four. The column portions 10 each have a cylindrical shape and are disposed at four equally spaced positions in the circumferential direction centered on the reference axis C and at the four corners of the lower frame portion 8 and the upper frame portion 9 in top view.

[0040] The backing plate 3 is a component for fixing the lower die 6 and is supported on the upper surface of the lower frame portion 8. In this example, the backing plate 3 has a rotationally symmetric shape centered on the reference axis C. Specifically, the backing plate 3 has a flat plate shape with a top view shape being a square. The phase of the top view shape (square) of the backing plate 3 and the top view shapes (squares) of the lower frame portion 8 and the upper frame portion 9 in the circumferential direction (at the vertices where the sides intersect each other) centered on the reference axis C is the same.

[0041] The slider 4 is a component for fixing the upper die 7 and is disposed above the backing plate 3 in a manner capable of moving in the vertical direction (the axial direction of the reference axis C). In this example, the slider 4 has a rotationally symmetric shape centered on the reference axis C. Specifically, the slider 4 has a flat plate shape with a top view shape being a circle.

[0042] The hydraulic cylinder 5 is a force generation source for applying a stamping force to the workpiece 11. In a state where its central axis is aligned with the reference axis C, it is supported by the upper frame portion 9. The hydraulic cylinder 5 has a piston rod (not shown) disposed coaxially with its central axis inside. As hydraulic pressure is introduced, an axial force proportional to the hydraulic pressure is imparted to the piston rod. The slider 4 is installed at the lower end of the piston rod. That is, the slider 4 is supported by the upper frame portion 9 via the hydraulic cylinder 5, integrated with the piston rod, and moves in the vertical direction.

[0043] The lower die 6 has a rotationally symmetric shape centered on a first central axis as its own central axis. The lower die 6 is fixed to the upper surface of the backing plate 3 in a state where the first central axis is aligned with the reference axis C.

[0044] The upper die 7 has a rotationally symmetric shape centered on the second central axis that serves as its own central axis. The upper die 7 is fixed to the lower surface of the slider 4 in a state where the second central axis coincides with the reference axis C. Therefore, the lower die 6 and the upper die 7 are arranged coaxially with each other.

[0045] When performing stamping on a workpiece 11 having a rotationally symmetric shape centered on the workpiece central axis that serves as its own central axis using a stamping machine 1 having the above structure, as Figure 2 shown, the workpiece 11 is arranged between the lower die 6 and the upper die 7. More specifically, the workpiece 11 is set on the lower die 6 in a state where the workpiece central axis of the workpiece 11 coincides with the reference axis C. And in this state, the upper die 7 is moved downward by the hydraulic cylinder 5, thereby approaching the upper die 7 to the lower die 6 in the axial direction of the reference axis C. Thereby, stamping is performed on the workpiece 11 between the lower die 6 and the upper die 7.

[0046] In addition, there is no particular requirement for the type of stamping at this time. That is, the type of this stamping, for example, in addition to Figure 3 upsetting shown in (A) of Figure 3 backward extrusion shown in (B) of Figure 3 forward extrusion shown in (C) of Figure 3 blanking shown in (D) of

[0047] In the stamping method of the present example as described above, when performing stamping on a workpiece 11 having a rotationally symmetric shape using a stamping machine 1 equipped with a hydraulic cylinder 5, the first central axis serving as the central axis of the lower die 6 and the second central axis serving as the central axis of the upper die 7 are respectively arranged coaxially with the reference axis C, and, as the lower die 6, the upper die 7, the backing plate 3, the slider 4, and the frame 2, components having a rotationally symmetric shape centered on the reference axis C are each used, and when performing stamping on the workpiece 11 between the lower die 6 and the upper die 7, the workpiece central axis serving as the central axis of the workpiece 11 is arranged coaxially with the reference axis C. Therefore, when performing stamping on the workpiece 11, the relative inclination amount between the lower die 6 (the first central axis) and the upper die 7 (the second central axis) generated by the elastic deformation of each of the lower die 6, the upper die 7, the backing plate 3, the slider 4, and the frame 2 can be suppressed to be small. In other words, stamping can be performed on the workpiece 11 in a state where this inclination amount is below a predetermined specified value. Therefore, the machining accuracy for the workpiece 11 can be improved and the energy loss can be suppressed to be small.

[0048] [Second Example of Embodiment]

[0049] Use Figures 5 to 7 Describe the second example of the implementation mode of the present invention.

[0050] In this example, the lower frame part 8a and the upper frame part 9a of the frame 2a constituting the press 1a each have a short cylindrical shape centered on the reference axis C.

[0051] In addition, the frame 2a has a structure capable of respectively changing the number of column parts 10 and the arrangement phase of the column parts 10 in the circumferential direction. For this purpose, in this example, the lower frame part 8a has lower fitting holes 12 at a plurality of positions equally spaced in the circumferential direction. The upper ends of the lower fitting holes 12 are open, and the lower end parts of the column parts 10 can be detachably fitted and held therein. In addition, the upper frame part 9a has upper fitting holes (not shown) at a plurality of positions equally spaced in the circumferential direction corresponding to the lower fitting holes 12 in the up-down direction. The lower ends of the upper fitting holes are open, and the upper end parts of the column parts 10 can be detachably fitted and held therein. Thus, by being able to select whether to provide the column parts 10 at a plurality of positions equally spaced in the circumferential direction where the lower fitting holes 12 and the upper fitting holes exist, the number of column parts 10 provided in the frame 2a and the arrangement phase of the column parts 10 in the circumferential direction can be respectively changed.

[0052] In this example, the column parts 10 are arranged such that in the case of integrally observing the workpiece 11 and the plurality of column parts 10, the aggregate of the workpiece 11 and the plurality of column parts 10 has a rotationally symmetric shape centered on the reference axis C. Thus, during stamping, the relative inclination amount between the lower die 6 (first central axis) and the upper die 7 (second central axis) can be more effectively suppressed.

[0053] Next, while referring to Figure 6 (A) to Figure 6 (C) of Figure 7 and Figure 7 (A) to

[0054] Figure 6 (C) of Figure 6 describe a specific example of the arrangement of the column parts 10 such that the aggregate of the workpiece 11 and the plurality of column parts 10 has a rotationally symmetric shape centered on the reference axis C.

[0054] Figure 6 (A) to Figure 6 (C) are examples in the case where the order of rotational symmetry n (n: an integer of 2 or more) related to the shape of the workpiece 11 is 3 (n = 3). In addition, in Figure 6 (A) to Figure 6 (C), for convenience, the top view shape of such a workpiece 11 is shown as an equilateral triangle. The minimum number of column parts 10 for realizing the arrangement of the column parts 10 such that the aggregate of the workpiece 11 and the plurality of column parts 10 has a rotationally symmetric shape centered on the reference axis C when n = 3 is three. For example, as in Figure 6 (A) andFigure 6 As shown in (B) of FIG. Figure 6 , three column portions 10 are arranged at equal intervals in the circumferential direction centered on the reference axis C. Figure 6 FIG. Figure 6 (A) is an example in which the column portions 10 are arranged at the same circumferential positions as the respective vertices of the equilateral triangle. Figure 6 FIG. Figure 6 (B) is an example in which the column portions 10 are arranged at the same circumferential positions as the central portions of the respective sides of the equilateral triangle. Another number of column portions 10 for achieving a configuration in which the workpiece 11 with n = 3 and the aggregate of the plurality of column portions 10 form a rotationally symmetric shape centered on the reference axis C is six. For example, as shown in Figure 6 FIG. Figure 6 (C), six column portions 10 are arranged at equal intervals in the circumferential direction centered on the reference axis C.

[0055] Figure 6 FIG. Figure 6 (C) is an example in which the column portions 10 are arranged at the same circumferential positions as the respective vertices and the central portions of the respective sides of the equilateral triangle.

[0056] Similarly, when the order of rotational symmetry related to the shape of the workpiece 11 is n, the number of column portions 10 for achieving a configuration in which the workpiece 11 and the aggregate of the plurality of column portions 10 form a rotationally symmetric shape centered on the reference axis C increases according to the relationship of n×2 k (k: 0 or a positive integer (k = 0, 1, 2, 3,...)). However, since the larger the number of column portions 10, the more difficult it becomes to supply and discharge the workpiece 11 to and from the stamping position and to replace the lower die 6 and the upper die 7, the minimum number (for example, three in the case of n = 3) is usually adopted.

[0057] Figure 7 FIG. Figure 7 (A) to Figure 7 FIG. Figure 7 (C) are examples in the case where the order of rotational symmetry n related to the shape of the workpiece 11 is 5 (n = 3). In addition, in Figure 7 FIG. Figure 7 (A) to Figure 7 FIG. Figure 7 (C), for convenience, the top view shape of such a workpiece 11 is shown as a regular pentagon. Also in this case, it is the same as the case of the workpiece 11 with n = 3 shown in Figure 6 FIG. Figure 6 (A) to Figure 6 FIG. Figure 6 (C), and thus the repeated description is omitted.

[0058] In addition, in this example, the bolster plate 3a of the stamping machine 1a has a disk shape centered on the reference axis α. Other structures and functions and effects are the same as those of the first example of the embodiment.

[0059] [Third Example of the Embodiment]

[0060] Using Figure 8 and Figure 9Example 3 of the embodiment of the present invention.

[0061] This example is an example in which a workpiece 11a having a non-rotationally symmetric shape centered on a workpiece central axis that is the central axis of itself is subjected to stamping using a hydraulic press 1b.

[0062] In addition, when the workpiece 11a has a portion (shaft portion, cylindrical portion, annular portion, etc.) having a central axis as its main part, the central axis of this main part can be defined as the workpiece central axis. In contrast, when the workpiece 11a does not have a portion (shaft portion, cylindrical portion, annular portion, etc.) having a central axis as its main part, a vertical axis passing through, for example, the geometric center of the top view shape of the workpiece 11a, a vertical axis passing through the center of gravity of the workpiece 11a, or a vertical axis passing through the center of a circle or a quadrilateral (rectangle, square) circumscribing the top view shape of the workpiece 11a can be defined as the workpiece central axis. That is, in this case, the position of the workpiece central axis within the workpiece 11a varies depending on the definition method of the workpiece central axis.

[0063] In summary, in this example, in order to perform stamping on the workpiece 11a, with the workpiece 11a disposed between the lower die 6a and the upper die 7a, the workpiece central axis is arranged parallel to the reference axis C (that is, in this state, the workpiece 11a has a non-rotationally symmetric shape when viewed from the axial direction of the reference axis C). In addition, in this state, the axes of the lower die 6a and the upper die 7a that are on the same straight line as the workpiece central axis become the respective central axes (first central axis, second central axis) of the lower die 6a and the upper die 7a. In this example, since the workpiece 11a has a non-rotationally symmetric shape centered on the workpiece central axis, the lower die 6a and the upper die 7a also have non-rotationally symmetric shapes centered on their respective central axes (first central axis, second central axis).

[0064] From the above description, it can be seen that in this example, since there is a case where the position of the workpiece central axis within the workpiece 11a varies depending on the definition method of the workpiece central axis, there is also a case where the position of the first central axis within the lower die 6a and the position of the second central axis within the upper die 7a also vary depending on the definition method of the workpiece central axis. However, in this example, as long as the position of the first central axis within the lower die 6a and the position of the second central axis within the upper die 7a that are coaxial with each other are determined, the "radial positioning process" and the "stamping process" described later can be performed using this position, so there is no particular problem.

[0065] In this example, the workpiece 11a, the lower die 6a, and the upper die 7a each have a non-rotationally symmetric shape centered on their own central axes. Therefore, even in Figure 8As shown, when the central axes (the first central axis and the second central axis) of the lower die 6a and the upper die 7a are coaxially arranged with the reference axis C, when stamping the workpiece 11a, there is also a tendency for relative inclination to occur between the lower die 6a (the first central axis) and the upper die 7a (the second central axis).

[0066] (Radial positioning process) Therefore, in this example, various changes are made to the radial positions of the lower die 6a and the upper die 7a centered on the reference axis C. Specifically, various changes are made to the radial offset amounts of the central axes of the lower die 6a and the upper die 7a relative to the reference axis C, and for each such offset amount, a test of stamping the workpiece 11a is carried out. And in this test, the relative inclination amount (inclination angle) between the lower die 6a (the first central axis) and the upper die 7a (the second central axis) generated when stamping the workpiece 11a is measured. For this purpose, specifically, laser displacement gauges 13 are arranged at four positions on the upper surface of the backing plate 3 in the imaginary plane orthogonal to the first central axis, which are equally spaced in the circumferential direction centered on the reference axis C. Then, based on the vertical positions of four positions on the lower surface of the upper die 7a (which can also be the lower surface of the slider 4a) in the imaginary plane orthogonal to the second central axis, which are equally spaced in the circumferential direction centered on the reference axis C, measured by these laser displacement gauges 13, the relative inclination amount between the lower die 6a and the upper die 7a is measured. Then, based on this measurement result, the relationship between Figure 9 the above-mentioned offset amount (horizontal axis) and the above-mentioned inclination amount (vertical axis) as shown is obtained.

[0067] In addition, Figure 9 The inclination amount (vertical axis) under the relationship shown can be, for example, any one of the inclination amount at the start position of the stamping process, the inclination amount at the end position (bottom dead center of the upper die 7a) of the stamping process, and the average value of the inclination amounts during the stamping process. However, regarding the machining accuracy of the workpiece 11a, since it is important to suppress the inclination amount at the end position of the stamping process to be small, Figure 9 the inclination amount (vertical axis) under the relationship shown is preferably set to the inclination amount at the end position of the stamping process.

[0068] In short, in this example, using the relationship obtained as described above, Figure 9 the radial positions (the above-mentioned offset amounts) of the lower die 6a and the upper die 7a at which one of the above-mentioned inclination amounts becomes below a specified value are determined. In particular, in this example, the specified value related to the above-mentioned inclination amount is set to a value smaller than the inclination amount S0 when the above-mentioned offset amount is 0. That is, in this example, using Figure 9 the relationship, the radial position at which the above-mentioned offset amount is not 0 and at which the above-mentioned inclination amount is smaller than the case where the above-mentioned offset amount is 0 is determined (preferably the above-mentioned inclination amount becomes the minimum value Smin radial position (offset δ min ).

[0069] (Stamping process) Then, in a state where the lower die 6a and the upper die 7a are arranged at a radial position determined as described above (in other words, in a state where the radial offset of the central axes of the lower die 6a and the upper die 7a with respect to the reference axis C is adjusted to the offset determined as described above), the workpiece 11a is subjected to stamping. As a result, the above-mentioned tilt amount during stamping of the workpiece 11a can be suppressed, so that the machining accuracy of the workpiece 11a can be improved and the energy loss can be reduced.

[0070] In addition, in the case of conducting the above test, there are countless choices for the direction (radial direction) in which the central axes of the lower die 6a and the upper die 7a are offset with respect to the reference axis C, and any direction can be selected. In addition, the selected direction is not limited to one, and multiple directions can also be selected. In the case of setting multiple selected directions, find for each selected direction Figure 9 relationship. And as long as the relationship that can minimize the above-mentioned tilt amount is adopted from these relationships, the machining accuracy of the workpiece 11 can be improved more effectively.

[0071] In addition, in this example, Figure 9 the offset under the relationship of is set as the offset of the central axes of the lower die 6a and the upper die 7a with respect to the reference axis C. However, in the case of implementing the present invention, it is also possible to Figure 9 the offset under the relationship of is set as the offset of a part other than the central axes of the lower die 6a and the upper die 7a (for example, a circumferential part of the outer peripheral surface of the lower die 6a and the upper die 7a) with respect to the reference axis C.

[0072] In addition, the laser displacement meter 13 can be removed after the above test or left as it is.

[0073] In this example, by only changing the above-mentioned offset of the existing stamping machine, the machining accuracy of the workpiece 11a can be improved and the energy loss can be reduced, so that the machining cost of the workpiece 11a can be suppressed. Other structures and functions are the same as those of the first example of the embodiment.

[0074] [Fourth example of the embodiment]

[0075] Use Figure 10 to illustrate the fourth example of the embodiment of the present invention. This example is a modification of the third example of the embodiment.

[0076] In this example, the hydraulic press 1c is provided with guide rods 14 and guide sleeves 15. The guide rods 14 extend upward from four portions that are circumferentially equally spaced about the reference axis C on the upper surface of the backing plate 3 existing in the imaginary plane orthogonal to the first central axis of the lower die 6a. The guide sleeves 15 extend downward from four portions on the lower surface of the slider 4a existing in the imaginary plane orthogonal to the second central axis of the upper die 7a and that are vertically aligned with the guide sleeves 15. Further, the guide rods 14 and the guide sleeves 15 existing at positions vertically aligned with each other are fitted together so as to be free from play and to permit relative displacement in the vertical direction. Thereby, the relative tilt amount between the lower die 6a (first central axis) and the upper die 7a (second central axis) generated during stamping of the workpiece 11a can be suppressed to be smaller.

[0077] In addition, by increasing the number of the guide rods 14 and the guide sleeves 15 and / or increasing the diameters of the guide rods 14 and the guide sleeves 15, the above-described tilt amount generated during stamping of the workpiece 11a can be suppressed to be smaller. However, if the number of the guide rods 14 and the guide sleeves 15 is increased and / or the diameters of the guide rods 14 and the guide sleeves 15 are increased, the manufacturing cost of the press 1c increases accordingly. In this regard, in this example, by using Figure 9 the relationship to adjust the radial offset amounts of the central axes of the lower die 6a and the upper die 7a with respect to the reference axis C, the above-described tilt amount can be suppressed to be small. Therefore, it is not necessary to excessively increase the number of the guide rods 14 and the guide sleeves 15 or to excessively increase the diameters of the guide rods 14 and the guide sleeves 15. Accordingly, the manufacturing cost of the press 1c can be suppressed.

[0078] In addition, by changing the positions of the guide rods 14 and the guide sleeves 15, the diameter of the lower die 6a, the diameter of the upper die 7a, and other parameters that may have an influence, the above-described tilt amount can be further suppressed to be small. In the case where there are three or more such parameters, an orthogonal array can be used to adopt a combination with a smaller (preferably the smallest) above-described tilt amount. Other structures and functions and effects are the same as those of the third example of the embodiment.

[0079] [Fifth Example of the Embodiment]

[0080] Use Figure 11 and Figure 12 to describe the fifth example of the embodiment of the present invention.

[0081] This example is an example in which a mechanical press 1d is used to perform stamping on a workpiece. The workpiece to be processed may be a workpiece 11 having a rotationally symmetric shape about a workpiece central axis that is its own central axis, or may be a workpiece 11a having a non-rotationally symmetric shape about a workpiece central axis that is its own central axis.

[0082] In the punching machine 1d of this example, the slider 4b is guided in such a manner that its outer peripheral edge portion can move in the vertical direction (the axial direction of the reference axis C) relative to the frame 2b. Further, the slider 4b can be moved in the vertical direction by a link mechanism 16 that transmits the power generated by an electric motor (not shown).

[0083] The link mechanism 16 is disposed above the slider 4b and includes a crankshaft 17 as a first link member and a connecting rod 18 as a second link member. The crankshaft 17 includes: a pair of rotary shaft portions 19 coaxially disposed on both axial sides; an offset shaft portion 20 disposed in the axial middle portion parallel to the pair of rotary shaft portions 19; and a pair of connecting portions 21 that connect the ends of the pair of rotary shaft portions 19 on the approaching side to the both ends of the offset shaft portion 20, respectively. Such a crankshaft 17 is supported in such a manner that the pair of rotary shaft portions 19 and the offset shaft portion 20 are horizontally disposed and the pair of rotary shaft portions 19 are rotatable relative to the frame 2b. Regarding the connecting rod 18, its upper end portion is supported relative to the offset shaft portion 20 so as to be rotatable about the offset shaft portion 20, and its lower end portion is supported relative to the central portion of the upper end portion of the slider 4b so as to be rotatable about an axis 22 parallel to the offset shaft portion 20. That is, the link mechanism 16, when combined with the slider 4b in this way, constitutes a slider-crank mechanism that reciprocates the slider 4b in the vertical direction as the crankshaft 17 rotates about the pair of rotary shaft portions 19. Further, the rotation of the crankshaft 17 about the pair of rotary shaft portions 19 is powered by an electric motor (not shown).

[0084] In the punching machine 1d of this example, as Figure 12 shown, the inclination of the connecting rod 18 relative to the reference axis C causes a force F acting on the slider 4b that is inclined relative to the reference axis C. The force F includes a component in a direction orthogonal to the vertical direction (the axial direction of the reference axis C), which is the moving direction of the slider 4b. Therefore, as Figure 11 shown, even if the central axes (the first central axis and the second central axis) of the lower die 6 (or 6a) and the upper die 7 (or 7a) that are coaxially disposed with each other are coaxially disposed with the reference axis C, when performing punching on the workpiece 11 (or 11a), the slider 4b will be inclined due to the above-mentioned component, and thus has a tendency to cause relative inclination between the lower die 6 (or 6a) (the first central axis) and the upper die 7 (or 7a) (the second central axis).

[0085] Therefore, also in the case of this example, the same test as in the third example of the embodiment is performed to obtain Figure 9The relationship as shown, i.e., the relationship between the radial offset and the relative inclination amount. The radial offset is the radial offset of the central axes of the lower die 6 (or 6a) and the upper die 7 (or 7a) relative to the reference axis C, and the relative inclination amount is the relative inclination amount between the lower die 6 (or 6a) (the first central axis) and the upper die 7 (or 7a) (the second central axis) generated when stamping the workpiece 11 (or 11a). Then, using this relationship, the central axes of the lower die 6 (or 6a) and the upper die 7 (or 7a) are arranged at a position where the above offset is not 0 and where the above inclination amount is smaller than the case where the above offset is 0 (preferably at a position where the inclination amount becomes the smallest). Then, by performing stamping on the workpiece 11 (or 11a) in this state, the machining accuracy for the workpiece 11 (or 11a) is improved and the energy loss is reduced.

[0086] In addition, in the case of this example, by changing the rotational speed of the crankshaft 17 during stamping to a small value after determining the above offset, the above inclination amount can be made smaller. Other structures and functions and effects are the same as those of the third example of the embodiment.

[0087] The present invention can be implemented by appropriately combining the structures of the above embodiments within a non - conflicting range. The present invention can be implemented, for example, when manufacturing metal components constituting a rolling bearing (the inner ring, outer ring of a rolling bearing, the hub ring, inner ring, outer ring, etc. constituting a hub unit bearing for rotatably supporting an automobile wheel relative to a suspension device).

[0088] Explanation of reference numerals

[0089] 1, 1a, 1b, 1c, 1d Press 2, 2a, 2b Frame 3, 3a, 3b Cushion plate 4, 4a, 4b Slide block 5 Hydraulic cylinder 6, 6a Lower die 7, 7a Upper die 8, 8a Lower side frame part 9, 9a Upper side frame part 10 Column part 11, 11a Workpiece 12 Lower side fitting hole 13 Laser displacement meter 14 Guide rod 15 Guide sleeve 16 Linkage mechanism 17 Crankshaft 18 Connecting rod 19 Rotating shaft part 20 Offset shaft part 21 Connecting part 22 Shaft.

Claims

1. A stamping method uses a stamping press having a frame with a reference axis, a first die, a second die, and a hydraulic cylinder. With a workpiece having a workpiece central axis and a rotationally symmetric shape centered on the workpiece central axis disposed between the first die and the second die, the second die is pushed toward the first die by the hydraulic cylinder to bring the second die closer to the first die, thereby performing stamping on the workpiece between the first die and the second die. The first die is supported by the frame, the second die is supported by the frame so as to be movable closer to and farther from the first die in the axial direction of the reference axis, and the hydraulic cylinder generates a force in the direction of bringing the second die closer to the first die. In the stamping method, the shapes of the frame, the first die, and the second die are each set to a rotationally symmetric shape centered on the reference axis, and the stamping is performed on the workpiece in a state where the workpiece central axis is aligned with the reference axis. The frame has a first frame portion that supports the first die, a second frame portion that supports the second die, and a plurality of column portions that connect the first frame portion and the second frame portion. In the case where the number of rotational symmetries related to the shape of the workpiece is n, the number of the column portions is n×2 k , and the column portions are arranged at equal intervals in the circumferential direction centered on the reference axis, where n is a positive integer of 2 or more, and k is 0 or a positive integer.

2. A method for manufacturing a mechanical device, wherein the mechanical device includes a metal component, and in the method for manufacturing the mechanical device, a process of performing the stamping method according to claim 1 is included in the manufacturing process of the metal component.

Images