Upsetting device, upsetting method, and upsetting product

Abstract

To provide a swaging device that can reduce a degree of curvature to become a barrel shape, and provide a swaging method and a swaging workpiece.SOLUTION: A swaging device 1 includes a first mold 2 having a first press surface 21, a second mold 3 having a second press surface 31 opposed to the first press surface 21, and a drive unit 5 capable of driving the first mold 2 and the second mold 3 in the direction of relatively coming close or away. The swaging device sandwiches and presses an annular raw material 100 from both sides of the direction along an axis line A0 using the first press surface 21 and the second press surface 31. At least one press surface of the first press surface 21 and the second press surface 31 is the side of a cone assuming one point on a device axis line A1 conforming to the axis line A0 of the annular raw material 100 as the vertex at the time when pressing the annular raw material 100.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an upsetting apparatus for annular material, an upsetting method, and an upset product. [Background technology]

[0002] Conventionally, many annular rotating parts such as bearings, rollers, and gear parts are manufactured by cutting round bar material. For example, a technology has been disclosed in which a steel pipe is cut to a specified width to manufacture a cut ring, the cut ring is subjected to a specified cutting process, and then forged to manufacture a bearing race (see Patent Document 1). However, this type of cutting has a low yield rate and a significantly low productivity tact time because the parts are manufactured by cutting out the material. For this reason, there is an increasing need to press-form an annular material to a shape close to the final shape, and then perform only the finishing by cutting.For example, a technology has been disclosed in which a cylindrical material is compressed in the axial direction, and its center is protruded outward to form a bent portion (see Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-130673 A [Patent Document 2] Japanese Patent Application Publication No. 63-26230 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the technology of Patent Document 2 is used to increase the thickness of a thin bearing steel pipe by simply upsetting, the pipe takes on a barrel shape curved in the center. An object of the present invention is to provide an upsetting apparatus, an upsetting method, and an upsetting product that are capable of reducing the degree of curvature that results in a barrel shape. [Means for solving the problem]

[0005] A first aspect of the present invention provides an upsetting processing device comprising a first die having a first pressing surface, a second die having a second pressing surface opposite the first pressing surface, and a drive unit capable of driving the first die and the second die in a direction to move them relatively closer to or away from each other, and which clamps and presses a ring-shaped material between the first pressing surface and the second pressing surface from both sides in a direction along an axis, wherein at least one of the first pressing surface and the second pressing surface is a side surface of a cone with an apex at a point on the device axis that coincides with the axis of the ring-shaped material when the ring-shaped material is pressed.

[0006] The pressing surface may be a side surface of a cone, and in a cross section passing through the device axis and parallel to the device axis, the inclination angle θ of the inner angle between the device axis and the side surface of the cone may be 75° or more.

[0007] The pressing surface may be a side surface of a cone, and in a cross section passing through the device axis and parallel to the device axis, the inclination angle θ on the inner angle between the device axis and the side surface of the cone may be 83° or more and 89° or less.

[0008] The pressing surface is a side surface of a cone, and when a friction coefficient between the pressing surface and the annular material is μ in a cross section passing through the device axis and parallel to the device axis, the inclination angle θ of the inner angle between the device axis and the side surface of the cone is: θ=90°-tan -1 It may be μ.

[0009] The pressing surface may be a side surface of a cone, and in a cross section passing through the device axis and parallel to the device axis, an inclination angle θ on the inner angle between the device axis and the side surface of the cone may be 60° or more.

[0010] The pressing surface may be a side surface of a cone, and in a cross section passing through the device axis and parallel to the device axis, the inclination angle θ on the inner angle between the device axis and the side surface of the cone may be 76° or more and 88° or less.

[0011] The pressing surface is a side surface of a cone, and when the friction coefficient between the pressing surface and the annular material is μ in a cross section passing through the device axis and parallel to the device axis, the inclination angle θ of the inner angle between the device axis and the side surface of the cone is θ=90°-2×tan -1 It may be μ.

[0012] At least one of the first pressing surface and the second pressing surface may be provided with a positioning protrusion that is inserted into a central through hole of the annular material.

[0013] A second aspect of the present invention provides an upsetting processing method, comprising: an arrangement step of arranging an annular material between a first die having a first pressing surface and a second die having a second pressing surface opposite to the first pressing surface; and an upsetting step of clamping and pressing the annular material between the first pressing surface and the second pressing surface from both ends in a direction along an axis by driving the first die and the second die in a direction relatively approaching each other, wherein at least one of the first pressing surface and the second pressing surface is a side surface of a cone with an apex at a point on an apparatus axis that is aligned with the axis of the annular material when the annular material is pressed.

[0014] The swaging process may be a free swaging process in which the outer peripheral surface and the inner peripheral surface of the annular blank are not restricted.

[0015] The pressing surface is a side surface of a cone, and when the friction coefficient between the pressing surface and the annular material is μ in a cross section passing through the device axis and parallel to the device axis, the inclination angle θ of the inner angle between the device axis and the side surface of the cone is θ=90°-tan -1 It may also be μ.

[0016] The pressing surface is a side surface of a cone, and when the friction coefficient between the pressing surface and the annular material is μ in a cross section passing through the device axis and parallel to the device axis, the inclination angle θ of the inner angle between the device axis and the side surface of the cone is θ=90°-2×tan -1 It may also be μ.

[0017] The positioning process may include a positioning process of positioning the annular material by inserting a positioning protrusion centered on the device axis provided on at least one of the first pressing surface and the second pressing surface into a central through hole of the annular material.

[0018] A third aspect of the present invention provides a swaged product that is annular, has a central inner diameter portion on the inner diameter side at the center in the axial direction, a central outer diameter portion on the outer diameter side at the center, a one end side inner diameter portion on the inner diameter side at one end in the axial direction, and an other end side inner diameter portion on the inner diameter side at the other end in the axial direction, which is harder.

[0019] The central inner diameter portion may be at least 5% harder than the central outer diameter portion. Effect of the Invention

[0020] According to the present invention, it is possible to provide an upsetting apparatus, an upsetting method, and an upsetting product that are capable of reducing the degree of curvature that results in a barrel shape. [Brief description of the drawings]

[0021] [Figure 1] 1 is a schematic cross-sectional view of an upsetting apparatus 1 according to an embodiment. [Diagram 2] 1A to 1C are diagrams illustrating an upsetting method according to an embodiment. [Diagram 3] FIG. 4 is a diagram illustrating an upsetting method according to a first comparative example. [Figure 4] 10A to 10C are diagrams illustrating forces acting on an annular material 100 when an upsetting apparatus 1A of a first comparative embodiment is used. [Diagram 5] 1 is a diagram illustrating the relationship between the friction coefficient μ and the angle φ when an object of weight W is placed on an inclined surface. [Figure 6] 1 is a diagram illustrating the relationship between the friction coefficient and the friction angle when a force F is applied to an inclined surface to compress a member. [Figure 7] 11 is a table showing the shapes of upset products 200, 200A when φ is classified into different cases. [Figure 8]This is the result of an FEM analysis comparing the amount of radial material displacement of an upset processed product with and without an inclination of the pressing surface of the die. [Figure 9] FIG. 11 is a diagram showing equivalent strains of an upset product 200 in the embodiment and an upset product 200A in a first comparative embodiment. [Figure 10] 13 is a graph showing the FEM analysis results and actual measurements of the inner diameter dimensions and outer dimensions of the upper and lower surfaces of upset processed products 200, 200A when the die angle is changed from 90° to 83°. [Figure 11] 13 is a graph showing the inner diameter difference and the outer diameter difference near the upper surface and near the center line M in upset-processed products 200, 200A processed by changing the inclination angle θ of the pressing surface. [Figure 12] FIG. 12 is a diagram for explaining values ​​indicated by the vertical axis in FIG. [Figure 13] The results show the Vickers hardness measurements at different positions. [Figure 14] This is a diagram comparing grain flows in products processed using different processing methods. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] (Upsetting equipment) FIG. 1 is a schematic cross-sectional view of an upsetting apparatus 1 according to an embodiment of the present invention. In the embodiment, the upsetting apparatus 1 is an apparatus that compresses an annular material 100 in the direction of an axis A0 to expand the diameter and increase the thickness. Note that, although the annular material 100 is upset in the embodiment, the present invention is not limited to this, and may be an apparatus that upsets an angular annular material or an elliptical annular material, for example. In addition, although the upsetting apparatus 1 upsets the annular material 100 from the top and bottom directions, the present invention is not limited to this, and may be an apparatus that upsets the annular material 100 from the side directions, for example.

[0023] The upsetting device 1 is equipped with a lower die 2 (first die), an upper die 3 (second die) that has approximately the same shape as the lower die 2 and is disposed above the lower die 2, centered on the same device axis A1 as the lower die 2, a guide unit 4 that guides the relative movement of the upper die 3 and the lower die 2 in the vertical direction, and a drive unit 5 that drives the upper die 3 and the lower die 2 relatively in the vertical direction. The lower die 2 and the upper die 3 are collectively referred to as a die 10.

[0024] (Lower mold 2) The lower die 2 is substantially cylindrical, with a lower die pressing surface 21 (first pressing surface) provided on the upper surface. The lower die pressing surface 21 is part of the side surface of a cone that has a vertex at a point on the device axis A1 and whose diameter increases downward. A lower die positioning protrusion 22 that protrudes upward in a cylindrical shape is provided on the upper surface within a range of a predetermined diameter centered on the device axis A1. The outer diameter of the lower die positioning protrusion 22 is substantially equal to the inner diameter of the through hole 101 of the annular material 100. As shown in FIG. 1, in a cross section passing through the device axis A1, the inclination angle (lower die inclination angle) θ1 of the lower die pressing surface 21 on the inner angle side relative to the device axis A1 is less than 90°, and in this embodiment, the lower die inclination angle θ1 is 87°. In the embodiment, the lower die pressing surface 21 is the side surface of a cone, but is not limited to this and may be the side surface of another pyramid, for example a pyramid, depending on the shape of the annular material to be processed.

[0025] (upper mold 3) The upper die 3 is the same shape as the lower die 2 but upside down. That is, it is substantially cylindrical, and has an upper die pressing surface 31 (second pressing surface) on its lower surface that faces the lower die pressing surface 21. The upper die pressing surface 31 is part of the side surface of a cone that has a vertex at a point on the device axis A1 and whose diameter increases upward. On the lower surface, within a range of a predetermined diameter centered on the device axis A1, an upper die positioning protrusion 32 that protrudes downward in a cylindrical shape is provided. The outer diameter of the upper die positioning protrusion 32 is substantially equal to the inner diameter of the through hole 101 of the annular material 100. As shown in Figure 1, in a vertical cross section passing through the device axis A1, the inclination angle θ2 (upper mold inclination angle) on the inner angle side of the upper mold pressing surface 31 relative to the device axis A1 is less than 90°, and in this embodiment, the upper mold inclination angle θ2 is 87°. Like the lower die pressing surface 21, the upper die pressing surface 31 in this embodiment is the side surface of a cone, but is not limited to this and may be a pyramid or the like depending on the shape of the annular material to be processed.

[0026] (Guide part 4) The guide part 4 is a cylindrical member of a predetermined thickness arranged on the outer periphery of the lower mold 2 and the upper mold 3. The inner diameter of a through hole 41 of the guide part 4 is approximately the same as the outer diameter of the upper mold 3 and the lower mold 2. The guide part 4 and the lower mold 2 are placed on a pedestal 6. The lower die 2 and the upper die 3 are arranged with a certain distance between them in the device axis A1 direction and centered on the device axis A1 inside the through hole 41 of the guide part 4, with the upper die pressing surface 31 and the lower die pressing surface 21 facing each other. When the lower die 2 and the upper die 3 move relatively to each other in the device axis A1 direction, they are guided straight by the through hole 41 of the guide part 4.

[0027] (Drive unit 5) In this embodiment, the drive unit 5 drives the upper mold 3 in the direction of the device axis A1 in a direction approaching and moving away from the lower mold 2. However, the present invention is not limited to this, and may be any device that drives the upper mold 3 and the lower mold 2 relatively to each other in the direction of the device axis A1. The upsetting device of the embodiment is a free upsetting device that does not constrain the outer periphery of the annular raw material 100 during upsetting.

[0028] (Embodiment of upsetting method) FIG. 2 is a diagram illustrating the upsetting method according to the embodiment. 2(a) is a perspective view of the annular material 100 before processing. The annular material 100 is a body of revolution centered on an axis A0. Note that, although the workpiece processed by the upsetting apparatus 1 in the embodiment is the annular material 100, the workpiece is not limited thereto and may be, for example, an angular annular material or an elliptical annular material.

[0029] 2(b) is a diagram illustrating the positioning step of the upsetting method. The lower side of the through hole 101 of the annular material 100 is inserted into the outer side of the lower die positioning protrusion 22 of the lower die 2. As a result, the annular material 100 is positioned and arranged in the center of the lower die pressing surface 21. Then, the drive unit 5 is driven to lower the upper die pressing surface 31, and the upper die positioning protrusion 32 of the upper die 3 is inserted into the through hole 101 of the annular material 100. As a result, the upper die positioning protrusion 32 of the upper die 3 is inserted above the through hole 101 of the annular material 100. The axis A0 of the annular material 100 coincides with the device axis A1 of the upsetting apparatus 1, and the annular material 100 is held in the center of the upsetting apparatus 1.

[0030] 2(c) is a diagram illustrating the upsetting step of the upsetting processing method. The upper die 3 is further lowered by driving the driving unit 5, and the annular raw material 100 is compressed in the direction of the axis A0 (the device axis A1) with a predetermined pressure force, so that the annular raw material 100 is expanded in diameter and thickened in the direction perpendicular to the axis A0.

[0031] 2(d) and (e) are diagrams showing an upset-processed product 200, which is the state after processing of the annular raw material 100, where (d) is a cross-sectional view passing through and parallel to the axis A0, and (e) is a perspective view. The upset product 200 is compressed in the direction of the axis A0 from the state of the annular raw material 100, and is thickened in the direction perpendicular to the direction of the axis A0. In the embodiment of the upset product 200 shown in Fig. 2, the outer surface 200a and the inner surface 200b are linear extending vertically in the cross section shown in the figure, that is, they are not curved. In addition, the upper surface 200u and the lower surface 200d of the upset product 200 are shaped like the side surfaces (inner surfaces) of a cone corresponding to the upper die pressing surface 31 and the lower die pressing surface 21.

[0032] In the embodiment of the upset product 200 shown in Fig. 2, the outer surface 200a and the inner surface 200b are linearly extending vertically in the cross section shown in the figure. However, the scope of the present invention does not necessarily require a completely linear shape, and it is sufficient if the amount of outward protrusion is smaller than that of the first comparative embodiment described below, and also includes cases where the product protrudes inward.

[0033] (Comparative upsetting method) FIG. 3 is a diagram illustrating the upsetting method of the first comparative embodiment. 3(a) is a perspective view of an unprocessed circular ring material 100. The circular ring material 100 is the same as in the embodiment.

[0034] 3(b) is a diagram for explaining the positioning step of the upsetting method of the first comparative embodiment. The upsetting apparatus 1A of the first comparative embodiment differs from the upsetting apparatus 1 of the embodiment in the shapes of the lower die pressing surface 21A and the upper die pressing surface 31A. The lower die pressing surface 21A and the upper die pressing surface 31A of the first comparative embodiment are not the side surfaces of a cone, but are flat surfaces extending in a direction perpendicular to the device axis A1 (horizontal direction). In the positioning step, similarly to the embodiment, the lower side of the through hole 101 of the annular material 100 is inserted into the outer side of the lower die positioning protrusion 22A of the lower die 2A. This positions and disposes the annular material 100 at the center of the lower die pressing surface 21A. Then, the drive unit is driven to lower the upper die pressing surface 31A and insert the upper die positioning protrusion 32A of the upper die 3A into the through hole 101 of the annular material 100. As a result, the upper die positioning protrusion 32A of the upper die 3A is inserted above the through hole 101 of the annular material 100. The axis A0 of the annular material 100 coincides with the device axis A1 of the upsetting apparatus 1A, and the annular material 100 is held in the center of the upsetting apparatus 1A.

[0035] 3(c) is a diagram illustrating the upsetting process of the upsetting method in the comparative embodiment. The upper die 3A is further lowered by driving the driving unit 5. This causes the annular raw material 100 to be compressed in the direction of the axis A0 (the device axis A1), and the diameter and thickness of the annular raw material 100 are increased in the direction perpendicular to the axis A0.

[0036] 3(d) and (e) are diagrams showing an upset product 200A after processing in a comparative embodiment, where (d) is a cross-sectional view passing through the axis A0 and parallel to the axis A0, and (e) is a perspective view. The upset product 200A of the first comparative embodiment is compressed in the axis A0 direction from the state of the annular raw material 100 as in the embodiment, and is thickened in the direction perpendicular to the axis A0 direction. The upset product 200A of the first comparative embodiment differs from the upset product 200 of the embodiment in that the central parts of the outer surface 200Aa and the inner surface 200Ab are curved and expanded outward, which is called a barrel shape.

[0037] (Why the first comparative form is barrel-shaped) The reason why the first comparative embodiment has such a barrel shape will be explained. When a load F acts on an object and it moves a distance s, it is most stable for the object to move in such a way that the work W = F × s is minimized. In other words, when F is constant, it is most stable for the object to move in such a way that s is the smallest. Even when the annular raw material 100 is upset between the upper mold 3 and the lower mold 2 having flat pressing surfaces as in the first comparative example, the movement in which the movement distance s is small is considered to be the most stable movement.

[0038] As an example, when a circular ring-shaped material 100 having an outer diameter (radius) of 6 mm, an inner diameter (radius) of 5 mm, and a height of 10 mm is set at a constant volume and a compression rate of 50%, the following occurs. (1) If the inner diameter does not change, the outer diameter (radius) increases from 6 mm to (√47) mm ≒ 6.86 mm. In other words, the movement distance s of the outer diameter part from the axis A0 is 0.86 mm. (2) If the outer diameter does not change, the inner diameter (radius) decreases from 5 mm to (√14) mm ≒ 3.74 mm. In other words, the movement distance s of the outer diameter portion from the axis A0 is 1.26 mm. Therefore, in free upsetting without constraint, a change in the outer diameter dimension results in less work W than a change in the inner diameter dimension, and is therefore considered to be more stable. Therefore, when the annular material 100 is upset in the first comparative example, from the standpoint of stability, it is thought that the material is more likely to move to the outer diameter side and expand in diameter than to move to the inner diameter side and reduce in diameter.

[0039] 4 is a diagram illustrating the forces acting on the annular raw material 100 when the upsetting apparatus 1A of the first comparative embodiment is used. When the annular raw material 100 attempts to move toward the outer diameter side, a frictional force fi=μ×F (μ is the friction coefficient) acts between the upper die pressing surface 31A and the upper surface of the annular raw material 100, and between the lower die pressing surface 21A and the lower surface of the annular raw material 100, in the opposite direction to the direction r in which the material attempts to move, i.e., toward the inner diameter side.

[0040] On the other hand, the influence of the friction force fi is small near the center line M in the axis A0 direction of the annular raw material 100. For this reason, the amount of radial displacement of the material differs between the vicinity of the upper and lower surfaces of the annular raw material 100 and the vicinity of the center line M. In other words, the amount of radial deformation is large near the center line M and small near the upper and lower surfaces, and as a result, the upset product 200A is considered to have a barrel shape as shown in Figures 3(c), (d), and (e).

[0041] (Reason for the reduction in protrusion amount in the embodiment) Next, the reason why the outward protrusion amount is smaller in the embodiment than in the comparative example will be described. (1) Relationship between friction coefficient μ and friction angle φ Suppose an object of weight W is placed on an inclined plane, the inclination is gradually increased, and when the angle of inclination reaches an angle φ, the object begins to slide. Figure 5 is a diagram explaining the relationship between the friction coefficient μ and angle φ when an object of weight W is placed on a slope. As shown in the figure, when the slope angle is φ, the weight W is resolved into a direct force R perpendicular to the slope and a force P parallel to the slope. In this case, the static friction force f (f=μ×R) of the object is balanced with the force P trying to slide the object, so f=μ×R=P Therefore, the friction coefficient μ is μ=P / R=(Wsinφ) / (Wcosφ)=tanφ It becomes.

[0042] (2) Application to press fitting This relational expression μ = tanφ is applied to the press fitting (free press fitting with unconstrained sides) of the present application. Fig. 6 is a diagram for explaining the relationship between the coefficient of friction and the friction angle when a force F is applied to an inclined surface to compress a member. Hereinafter, the upper die pressing surface 31 and the upper surface side of the annular material 100 will be described as an example. F: Load R: Component force (direct pressure) of the load F in the direction perpendicular to the upper die pressing surface 31 of the upper die 3 P: Component force of the load F in the direction parallel to the upper die pressing surface 31 of the upper die 3 fp: Static frictional force acting in the opposite direction with the same magnitude as the force P φ: Inclination φ of the upper die pressing surface 31 with respect to the horizontal plane μ: Coefficient of friction between the upper die 3 and the upper surface of the annular material 100 fmax: Maximum frictional force Let it be.

[0043] Then, P = F × sinφ, R = F × cosφ, fmax = μ × R, fp = P (until fmax < P) It becomes.

[0044] When the object is slid as shown in Fig. 5, the object is stationary when P ≤ μ × R. However, in the case of press fitting as shown in Fig. 6, when P ≤ μ × R, the material moves in the outer diameter direction with a small movement distance. Therefore, the frictional force fi acting in the direction opposite to the direction in which the material moves, that is, the inward radial direction, also exists at the same time. However, since friction does not occur above the maximum frictional force fmax, the sum of the static frictional force fp and fi coincides with fmax. In the press fitting of the present invention, under the condition of P ≤ μ × R, the direction in which the object moves can be considered as the inward radial movement due to the force P parallel to the inclined surface and the movement to the outer diameter side due to free press fitting. The maximum frictional force fmax is calculated by the product of the force (direct pressure) R perpendicular to the slope and the friction coefficient μ. However, since this force acts in the opposite direction of the object moving down the slope, there exists a frictional force fp that acts in the opposite direction to the force P parallel to the slope, and a frictional force fi that acts in the opposite direction to the movement toward the outer diameter due to free upsetting, and the relationship between these is fmax = fp + fi.

[0045] That is, When P≦μ×R, Since fmax=fp+fi and fp=P, fi=fmax-fp=μ×RP=(μ×F×cosφ)-(F×sinφ)=(μ×F)×(cosφ-sinφ / μ) It becomes.

[0046] 7 is a table showing the shapes of the upset product 200 (embodiment) and 200A (first comparative embodiment) when classified according to φ. The size of the arrow indicates the magnitude of the friction force or the amount of displacement. (1) When φ=0 (first comparative example) fi = μ×F, fp = 0, and the friction force f is f = μ×F and acts in the inner diameter direction. Therefore, in the first comparative embodiment, as described above, the amount of deformation is small near the upper and lower surfaces that are in contact with the pressing surface, and the amount of radial deformation is large near the center line M, and as a result, the upset processed product 200A becomes barrel-shaped as shown in Figures 3(c), (d), and (e).

[0047] (2) When cosφ>sinφ / μ (embodiment) Since fp and P cancel each other out, the apparent friction force f is equal to fi. As a result, f is 0 in the inner diameter direction. <f<μ×Fとなる。 In this case, φ is μ>sinφ / cosφ=tanφ, and φ <tan -1 It can be calculated using μ. In this embodiment, the apparent frictional force is smaller than that of the first comparative embodiment, and therefore the difference between the amount of deformation near the upper and lower surfaces that contact the pressing surface and the amount of radial deformation near the center line M is smaller than in the first comparative embodiment.

[0048] (3) When cosφ=sinφ / μ (embodiment) Since fi = 0 and fp = fmax = P, fp is balanced and canceled out by P, so the apparent friction force f is f = 0. In this case, φ is μ = sinφ / cosφ = tanφ, so φ = tan -1 It can be calculated using μ. Therefore, cosφ=sinφ / μ is the most preferable range in the embodiment, and there is no difference between the amount of deformation near the upper and lower surfaces that are in contact with the pressing surface and the amount of deformation in the radial direction near the center line M. Therefore, the inclination φ of the upper pressing surface 31 with respect to the horizontal plane is expressed as φ=tan -1 If μ (μ is the coefficient of friction) is set, the friction force f generated at the boundary surface between the die and the annular material 100 can be made to appear zero, and the amount of radial displacement of the material becomes equal near the center line M and at the boundary surface of the die. Therefore, as shown in Figures 2(d) and (e), the outer surface 200a and the inner surface 200b of the upset product 200 can be made linear extending vertically in the cross section shown in the figures.

[0049] (Verification results) Figure 8 shows the results of a Finite Element Method (FEM) analysis comparing the amount of material displacement in the radial direction of an upset product with and without an inclination of the pressing surface of the die. Figure 8(d) on the far right side of the figure shows the positions of the material displacement shown in Figures 8(a),(b),(c). The friction coefficient μ between steel types and die materials when using general lubricants is 0.03 to 0.12, with a maximum of 0.25, but in this FEM analysis, a frequently used friction coefficient μ of 0.05 was applied.

[0050] The various conditions are as follows: Analysis method: FEM Circular material Steel type: SUJ2 Inner diameter: 14.2mm Outer diameter: 28.4mm Height: 50.5mm Friction coefficient μ: 0.05 Compressive force: (a) 724kN, (b) 811kN, (c) 838kN Compression ratio: 50%

[0051] 8(c) shows an upset product 200I obtained by upsetting the annular material 100 using an upsetting device having upper and lower die pressing surfaces that extend parallel to each other in the horizontal direction under ideal friction-free processing conditions. The upset product 200I processed under ideal processing conditions has the same radial material displacement amount near the center line M as near the upper and lower surfaces.

[0052] Figure 8(a) shows a first comparative form of upsetting processed product 200A obtained when a circular material 100 is upset using an upsetting processing apparatus 1A having an upper die pressing surface 31A and a lower die pressing surface 21A extending parallel to each other and horizontally under realistic processing conditions in which friction is present. According to the first comparative example, the frictional force (μ×F) acts in the inward direction near the upper and lower surfaces, so the amount of displacement of the material is small. Also, the influence of the frictional force is small near the center line M, so the amount of displacement is large.

[0053] FIG. 8(b) shows the present embodiment. In this embodiment, realistic friction exists, but for the annular material 100, φ=tan -1 This is an upsetting product 200 obtained by upsetting an annular material 100 using an upsetting device 1 having an upper die pressing surface 31 and a lower die pressing surface 21, which are inclined surfaces of μ (μ is the coefficient of friction). According to the embodiment, it can be seen that the difference in the amount of material displacement between the vicinity of the center line M and the vicinity of the upper and lower surfaces is small, and is close to the ideal state of Fig. 8(c) where there is no friction.

[0054] (Regarding the inclination angle θ) As described above, in the embodiment, the upper mold inclination angle θ2 and the lower mold inclination angle θ1 are 87°. The effect of this will be described. Note that the following description is common to the upper mold inclination angle θ2 and the lower mold inclination angle θ1, so it will be commonly described as the inclination angle θ. As shown in FIG. 6, the relationship between the angle φ and the inclination angle θ of the mold 10 is θ=90°-φ=90°-tan-1 It is μ. In addition, this relation is Since tanθ=1 / tanφ=1 / μ, θ=tan ―1 It can also be expressed as (1 / μ). In other words, if μ is known, the inclination angle θ can be calculated. Note that in the experimental estimation method for the friction coefficient μ, the accuracy of μ includes an error of about ±0.02, so the inclination angle includes the θ calculated here up to ±1.5°.

[0055] (Relationship between μ and inclination angle θ) In the embodiment, if μ=0.05, the inclination angle θ at which the apparent friction force f becomes f=0 is given by: θ=tan -1 (1 / μ) =tan -1 (1 / 0.05) When the angle is 87°, the amount of radial displacement of the annular blank 100 becomes equal in the vicinity of the center line M and at the die boundary surface, and the formed upset product 200 does not have a barrel shape. In addition, since μ has an error, the inclination angle θ is within the range of 85.5°≦θ≦88.5° (85.5° or more and 88.5° or less).

[0056] (Preferable range to avoid bending) The friction coefficient μ varies depending on the metal material used as the die in the upsetting device 1, the material of the annular material, the lubricant oil, etc. Generally, the maximum friction coefficient μmax is about 0.25, so θ=tan -1 From (1 / μ), θ = 75° (rounded down to the nearest whole number). Among these, the range that is usually used is 0.03≦μ≦0.12. In this case, 83°≦θ≦89° (83° or more and 89° or less).

[0057] Figure 9(a) shows the results of an analysis of the equivalent strain of an upset-processed product 200A in the first comparative embodiment with μ = 0.05 and an inclination angle θ = 90°, and Figure 9(b) shows the results of an analysis of the equivalent strain of an upset-processed product 200 in the embodiment with μ = 0.05 and an inclination angle θ = 87°.

[0058] The analysis method and various conditions are as follows. Analysis method: FEM Circular material Steel type: SUJ2 Inner diameter: 14.2mm Outer diameter: 28.4mm Height: 50.5mm Compressive force: (a) 724kN, (b) 811kN Compression ratio: 50%

[0059] The dotted line in the figure indicates the target shape of the upset product 200. As shown in the figure, in the embodiment, the equivalent strain was approximately uniform, while in the first comparative example, the equivalent strain value varied widely. Also, the upset product 200 in the embodiment was closer to the ideal shape.

[0060] Figure 10 is a graph showing the FEM analysis results of the inner diameter dimensions and outer dimensions of the upper and lower surfaces of the upset processed products 200, 200A when the die angle is changed from 90° to 83°, as well as the actual measured values ​​when the die angle is 90°, 88°, 87°, 86°, and 84°. The method for estimating the friction coefficient μ is described in the revised edition of Science of Plastic Processing (1st edition, March 14, 2014). The method involves ring compression, in which a ring-shaped test piece is compressed between parallel tools. When friction is low, the ring inner diameter expands, and when friction is high, the ring inner diameter shrinks. This change in the ring inner diameter is due to differences in the coefficient of friction. The method utilizes this change in the ring inner diameter due to differences in the coefficient of friction and determines the coefficient of friction by comparing the calculated results with the change in the ring inner diameter obtained experimentally. The result of checking with the experimental product this time was that the friction coefficient μ = 0.05.

[0061] The analysis method and various conditions are as follows. The following circular materials were used: Steel type: SUJ2 Inner diameter: 14.2mm Outer diameter: 28.4mm Height: 50.5mm In addition, upsetting was carried out under the following conditions. Press equipment: 4000kN mechanical press (hydraulic unit, manufactured by Rikenki Co., Ltd.) Press motion: Crank Press speed: 10spm Mold material: SKD11 Lubricant: G-3456 (manufactured by Nippon Kogyo Oil Co., Ltd.) Compression force: die angle 90° 748kN, 88° 801kN, 87° 834kN, 86° 773kN, 84° 657kN Compression ratio: 50% Analysis method: FEM Circular material Steel type: SUJ2 Inner diameter: 14.2mm Outer diameter: 28.4mm Height: 50.5mm Compression force: die angle 90° 724kN, 88° 788kN, 87° 811kN, 86° 765kN, 84° 664kN 83° 629kN Compression ratio: 50%

[0062] As shown in the figure, the actual measured values ​​of the outer diameter dimension A and inner diameter dimension a of the upset processed products 200, 200A are approximately consistent with the FEM analysis results based on the mechanism described in Figure 7, demonstrating the high reliability of the mechanism described in Figure 7.

[0063] (Change in shape due to change in θ) Fig. 11 is a graph based on the results of an FEM analysis showing the inner diameter difference and the outer diameter difference near the upper surface and near the center line M of upset-processed products 200, 200A processed by changing the inclination angle θ of the pressing surface of the upsetting device 1 when the friction coefficient μ is 0.05. Fig. 12 is a diagram explaining the values ​​indicated by the vertical axis in Fig. 11. As shown in Fig. 12, the outer diameter of the upper part of the upset-processed product 200 of the embodiment is A, the inner diameter of the upper part is a, the outer diameter of the central part is B, and the inner diameter of the central part is b.

[0064] The difference ba between the inner diameter b of the central portion and the inner diameter a of the upper portion is defined as the inner diameter difference. A positive value of ba indicates that the diameter of the central portion of the through hole of the upset-processed product 200 is larger than the diameter at the upper portion. A negative value of ba indicates that the diameter of the central portion of the through hole of the upset-processed product 200 is smaller than the diameter at the upper portion.

[0065] The difference BA between the upper outer diameter B and the upper outer diameter A is defined as the outer diameter difference. A positive value for BA indicates that the diameter of the central part of the outer diameter of the upset product 200 is larger than the diameter of the upper part, i.e., a barrel shape. A negative value for BA indicates that the diameter of the central part of the outer diameter of the upset product 200 is smaller than the diameter of the upper part, i.e., a shape with a recessed center.

[0066] As shown in Fig. 11, when the inclination angle θ of the die is changed from 90° to 83°, the values ​​of the inner diameter difference and the outer diameter difference change. The inclination angle of the die of 90° corresponds to the first comparative embodiment. Also, as shown in Fig. 11, when the die angle is changed, the inner diameter difference and the outer diameter difference become substantially equal. In other words, the amount of protrusion on the outer diameter side and the amount of constriction on the inner diameter side are considered to be substantially equal, and the protruding portion of the outer diameter portion becomes the concave portion of the inner diameter portion.

[0067] In the embodiment, when μ=0.05, the inclination angle θ is about 87° (=90°-tan -1 At this time, as shown in FIG. 11, the difference between the inner diameter and the outer diameter becomes approximately zero. In addition, the accuracy of the friction coefficient μ in the experimental estimation method includes an error of about ±0.02, so the inclination angle is set to 85.5°≦θ≦88.5° (85.5° or more and 88.5° or less) (=tan -1 (1 / μ)±1.5°).

[0068] (Inner protrusions on the inside) When the inclination angle θ becomes smaller than 87° (when the inclination with respect to the horizontal becomes larger), the value of the difference between the inner diameter and the outer diameter becomes negative. And when the inclination angle θ becomes 90°-2×tan -1 When μ is used, it is possible to manufacture an upset-processed product having an inward protrusion by the same amount as the upset-processed product 200A having an outward protrusion in the first comparative embodiment. Note that in the method of estimating the friction coefficient μ through experiments, the accuracy of μ includes an error of about ±0.02, so the inclination angle includes the inclination angle θ calculated here ±3.0°. That is, the inclination angle θ for producing an upset-processed product with the same inward protrusion as when pressed with a flat pressing surface is: Generally, the maximum friction coefficient μmax = 0.25 and θ = 60°, and within this, the range that is usually used is 0.03≦μ≦0.12. In this case, 76°≦θ≦88° (76° or more and 88° or less).

[0069] In this way, by changing the inclination angle θ, the radial position of the center of the upset product in the direction of the axis A0 can be changed relative to the upper and lower parts. In other words, by changing the inclination angle θ, it is possible to manufacture upset products of any shape, such as a barrel shape with an outward protrusion, a cylindrical shape with no curved sides, or a waist shape with an inward protrusion.

[0070] (hardness) Figure 13 shows the results of measuring Vickers hardness at different positions on (a) annular material 100 before processing, (b) an upset-processed product 200 processed by the upset processing apparatus 1 of the first comparative embodiment, and (c) an upset-processed product 200 processed by the upset processing apparatus 1 of the embodiment. The following circular materials were used: Steel type: SUJ2 Inner diameter: 14.2mm Outer diameter: 28.4mm Height: 50.5mm In addition, upsetting was carried out under the following conditions. Press equipment: 4000kN mechanical press (hydraulic unit, manufactured by Rikenki Co., Ltd.) Press motion: Crank Press speed: 10spm Mold material: SKD11 Lubricant: G-3456 (manufactured by Nippon Kogyo Oil Co., Ltd.) Compressive force: (b) 748kN, (c) 834kN Compression ratio: 50% The Vickers hardness was measured at 15 points in total, 1, 2, 3, 4, and 5 from the top in the longitudinal direction, and 3 points A, B, and C from the outer diameter side in the radial direction. The unit is HV, and the test load is 9.8N.

[0071] When an object is subjected to plastic deformation, obstacles (grain boundaries, precipitates, and other dislocations) accumulate as the deformation increases, causing an increase in density and resulting in work hardening, which increases the strength of the material. In other words, the more a material is deformed, the harder it becomes.

[0072] As described above, when the vicinity of the upper surface of the annular raw material 100 close to the upper die 3 and the vicinity of the lower surface of the annular raw material 100 close to the lower die 2 are subjected to a load by the mold 10, the material moves to the outer diameter side, which is a shorter moving distance, in the first comparative embodiment with θ=90° and the embodiment with θ=87°. Therefore, the degree of deformation is greater on the outer diameter side than on the inner diameter side.

[0073] As a result, the hardness of the upper portion (measured point 1) and the lower portion (measured point 5) of the annular material 100 are in the order of outer diameter portion (measured point A)>central portion (measured point B)>inner diameter portion (measured point C). This is the same in the first comparative embodiment and the embodiment.

[0074] On the other hand, since the central part (measurement point 3) is located in the middle of the upper mold 3 and the lower mold 2, the deformation is dominated by compression by the upper mold 3 and the lower mold 2, and as the compression rate of the material increases, the degree of deformation increases and the material becomes harder. That is, in the first comparative embodiment, the upper die 3 and the lower die 2 are horizontal, so the compression ratios of the outer diameter portion and the inner diameter portion are the same, there is no difference in the degree of deformation, and the hardness at the measurement points A, B, and C is approximately equal. However, in the embodiment, the pressing surfaces of the upper mold 3 and the lower mold 2 are inclined, so the compression ratio of the inner diameter portion is high and the compression ratio of the outer diameter portion is low. Therefore, there is a difference in the degree of deformation, with the outer diameter portion (measurement point A) < the center portion (measurement point B) < the inner diameter portion (measurement point C).

[0075] As described above, the upset product 200 of the embodiment has the hardest central portion of the inner diameter portion (side fixed point C), and the softest upper and lower portions of the inner diameter portion. Therefore, it becomes easier to perform H-shape processing by sandwiching the upper and lower portions of the softest inner diameter portion between dies and pressing them in, and then punching the pressed surface, which makes it easier to perform finish punching processing than the upset product 200 as an intermediate product according to the first comparative embodiment.

[0076] Figure 14 is a comparison of grain flows in products processed using different processing methods. 1A is a diagram showing grain flows of an upset-processed product 200 according to an embodiment, FIG. 1B is a diagram showing grain flows of an upset-processed product 200 according to a first comparative embodiment, and FIG. 1C is a diagram showing grain flows of an upset-processed product 200 according to a second comparative embodiment. The second comparative example is an upset product 200B obtained by restraining the outer diameter side of the annular raw material 100 with an outer wall and machining it into a rectangular shape.

[0077] In an upset product 200A according to a first comparative embodiment shown in FIG. 14(b), the grain flows in the vicinity of a center line M in the longitudinal direction of the annular raw material 100 are perpendicular to the axis A0, that is, horizontal. However, the grain flows near the upper surface pressed by upper die pressing surface 31 are not parallel to upper die pressing surface 31. Similarly, the grain flows near the lower surface pressed by lower die pressing surface 21 are not parallel to lower die pressing surface 21.

[0078] 14(c) shows an upset product 200B according to a second comparative embodiment, in which the grain flows in the vicinity of the longitudinal center line M of the annular raw material 100 are not perpendicular to the axis A0, i.e., are not horizontal. The grain flows in the vicinity of the upper surface pressed by the upper die pressing surface 31 are not parallel to the upper die pressing surface 31. The grain flows in the vicinity of the lower surface pressed by the lower die pressing surface 21 are also not parallel to the lower die pressing surface 21.

[0079] However, in the upset product 200 according to the embodiment shown in FIG. 14(a), the grain flows in the vicinity of the center line M in the longitudinal direction of the annular raw material 100 are perpendicular to the axis A0, that is, horizontal. The grain flow gradually inclines upward from center line M, and the grain flow near the upper surface pressed by upper die pressing surface 31 is approximately parallel to upper die pressing surface 31, that is, has the same inclination as upper die pressing surface 31. The grain flow gradually inclines downward from center line M, and the grain flow near the lower surface pressed by lower die pressing surface 21 is approximately parallel to lower die pressing surface 21, i.e., has the same inclination as lower die pressing surface 21. Compared with the first and second comparative examples, the intervals between the grain flows are generally uniform, indicating that forging has been performed without unevenness.

[0080] As described above, according to this embodiment, the annular material is pressed by gradually contacting it from the inside diameter with the pressing surface, which is the side surface of a cone with an inclination angle of less than 90°. This allows the cross-sectional shape of the inner and outer diameter surfaces to be linearly thickened. In addition, since the diameter can be expanded without bending or buckling in the center after processing, it is possible to increase the thickness of thin bearing steel pipes. The load of the press can be reduced to about 1 / 2.5 compared to when the side surface of the annular material 100 is flattened by restraining the side surface. [Explanation of symbols]

[0081] θ: Tilt angle θ1: Lower mold inclination angle θ2: Upper mold inclination angle θ2: Inclination angle μ: Friction coefficient A0: Axis line A1: Equipment axis 1: Upsetting equipment 10:Mold 2: Lower mold (first mold) 21: Lower die pressing surface (first pressing surface) 22: Lower die positioning protrusion 3: Upper mold (2nd mold) 31: Upper pressing surface (second pressing surface) 32: Upper die positioning protrusion 41:Through hole 5: Drive unit 100: Circular material (ring material) 101: Through hole 200: Upset processed products 200a: Outer surface 200b:Inner surface

Claims

1. A first mold having a first pressing surface; a second die having a second pressing surface opposed to the first pressing surface; a drive unit capable of driving the first mold and the second mold in a direction to move relatively closer to or away from each other, An upsetting processing device that sandwiches and presses an annular material between the first pressing surface and the second pressing surface from both sides in a direction along an axis, An upsetting processing apparatus, wherein the first pressing surface and the second pressing surface are sides of a cone having a vertex at a point on an apparatus axis that coincides with the axis of the annular material when the annular material is pressed.

2. The first pressing surface and the second pressing surface are side surfaces of a cone, In a cross section passing through the device axis and parallel to the device axis, the inclination angle θ of the inner angle between the device axis and the side surface of the cone is 75° or more.

2. The upsetting apparatus according to claim 1.

3. The first pressing surface and the second pressing surface are side surfaces of a cone, In a cross section passing through the device axis and parallel to the device axis, the inclination angle θ of the inner angle between the device axis and the side surface of the cone is 83° or more and 89° or less.

3. An upsetting apparatus according to claim 1 or 2.

4. The first pressing surface and the second pressing surface are side surfaces of a cone, In a cross section passing through the device axis and parallel to the device axis, when the friction coefficient between the annular material and each of the first pressing surface and the second pressing surface is μ, the inclination angle θ of the inner angle between the device axis and the side surface of the cone is: θ=90°-tan －１ μである、 The upsetting apparatus according to any one of claims 1 to 3.

5. The first pressing surface and the second pressing surface are side surfaces of a cone, In a cross section passing through the device axis and parallel to the device axis, the inclination angle θ of the inner angle between the device axis and the side surface of the cone is 60° or more.

2. The upsetting apparatus according to claim 1.

6. The first pressing surface and the second pressing surface are side surfaces of a cone, In a cross section passing through the device axis and parallel to the device axis, the inclination angle θ of the inner angle between the device axis and the side surface of the cone is 76° or more and 88° or less.

6. An upsetting apparatus according to claim 1 or 5.

7. The first pressing surface and the second pressing surface are side surfaces of a cone, In a cross section passing through the device axis and parallel to the device axis, when the friction coefficient between the annular material and each of the first pressing surface and the second pressing surface is μ, the inclination angle θ of the inner angle between the device axis and the side surface of the cone is: θ=90°−2×tan−1μ.

7. An upsetting apparatus according to claim 1, 5 or 6.

8. At least one of the first pressing surface and the second pressing surface is provided with a positioning protrusion to be inserted into a central through hole of the annular material. An upsetting apparatus according to any one of claims 1 to 7.

9. a positioning step of positioning an annular material between a first die having a first pressing surface and a second die having a second pressing surface opposite to the first pressing surface; a swaging process in which the annular blank is sandwiched and pressed between the first pressing surface and the second pressing surface from both ends in a direction along the axis by driving the first die and the second die in a direction in which they approach each other relatively, A method for upsetting, wherein the first pressing surface and the second pressing surface are sides of a cone having a vertex at a point on an apparatus axis that is aligned with the axis of the annular material when the annular material is pressed.

10. The upsetting step includes: A free upsetting process in which the outer peripheral surface and the inner peripheral surface of the annular blank are not constrained. The upsetting method according to claim 9.

11. The first pressing surface and the second pressing surface are side surfaces of a cone, In a cross section passing through the device axis and parallel to the device axis, when the friction coefficient between the annular material and each of the first pressing surface and the second pressing surface is μ, the inclination angle θ on the inner angle side between the device axis and the side surface of the cone is θ = 90 ° - tan - 1 μ. The upsetting method according to claim 9 or 10.

12. The first pressing surface and the second pressing surface are side surfaces of a cone, In a cross section passing through the device axis and parallel to the device axis, when the friction coefficient between the annular material and each of the first pressing surface and the second pressing surface is μ, the inclination angle θ on the inner angle side between the device axis and the side surface of the cone is θ = 90 ° - 2 × tan -1 μ. The upsetting method according to claim 9 or 10.

13. The placing step includes: A positioning step of positioning the annular material by inserting a positioning protrusion, which is provided on at least one of the first pressing surface and the second pressing surface and is centered on the device axis, into a central through hole of the annular material. The upsetting method according to any one of claims 9 to 12.

14. It is cyclic, The central inner diameter portion on the inner diameter side at the center in the axial direction is A central outer diameter portion on an outer diameter side at the center; an inner diameter portion on an inner diameter side at one end side of the axial direction; an inner diameter portion on the other end side of the inner diameter side at the other end side in the axial direction, Upset processed product.

15. The central inner diameter portion is at least 5% harder than the central outer diameter portion.

15. The upset product according to claim 14.

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