JP6792878B2 - Manufacturing method of press-molded products and press-molded products - Google Patents

Description

The present invention relates to a method for producing a press-molded product having a cylindrical portion, and a press-molded product produced by the manufacturing method.

Since the side peripheral wall of the metal part having a cylindrical portion is curved over the entire circumference, it is difficult to fix it to another member such as a support member. Therefore, a flat surface portion may be provided on a part of the side peripheral wall. By having a flat surface portion on a part of the side peripheral wall, this flat surface portion can be brought into contact with the flat surface portion of another member, so that the metal part can be fixed to the other member in a stable posture. it can.

However, when such a flat surface portion is formed by press molding, the remaining cylindrical portion is distorted due to the influence of the flow of metal at that time, and the roundness of the cross-sectional circle in the direction orthogonal to the axial direction in the cylindrical portion is rounded. Will decrease. A metal part having a cylindrical portion is often used by fitting a cylindrical portion of another member together, and a high roundness is often required for the cross-sectional circle of the cylindrical portion. Therefore, there has been a demand for a manufacturing method capable of manufacturing a metal part having a high roundness in the cross-sectional circle of the remaining cylindrical portion even if a flat portion is formed on a part of the side peripheral wall by press molding. ..

Therefore, in view of the above circumstances, the present invention manufactures a press-formed product in which the cross-sectional circle of the remaining cylindrical portion has a high roundness even if a flat portion is formed on a part of the side peripheral wall of the cylindrical portion. An object of the present invention is to provide a method and a press-molded product manufactured by the manufacturing method.

In order to solve the above problems, the method for manufacturing a press-molded product according to the present invention is
"A cross section that is orthogonal to the axial direction by forming a flat portion by press molding that applies an inward pressing force to a part of the side peripheral wall on the bottom side of the cylindrical portion of the bottomed cylindrical workpiece. It has a D-shaped tubular portion whose surface has a D-shape, a remaining cylindrical portion, and a tapered portion that extends from the cylindrical portion to the D-shaped tubular portion and whose side peripheral wall is gradually inclined. Mold the intermediate work and
By inserting a punch through the opening of the intermediate work and pressing the tapered portion in the axial direction of the cylindrical portion, the strain generated in the cylindrical portion during the formation of the D-shaped tubular portion is corrected, and the above-mentioned It enhances the roundness of the cross section in the cylindrical portion. "

When a force that presses inward is applied to a part of the side peripheral wall on the bottom side of the cylindrical part of the bottomed cylindrical work in a flat shape, the metal in that part flows inward to form a flat part. .. The side peripheral wall of the portion where the flat surface portion is formed has a D-shaped cross section, which is a cross section in the direction orthogonal to the axial direction, and therefore this portion is referred to as a “D-shaped tubular portion”. On the side peripheral wall of the intermediate work, the portion excluding the portion that has become a D-shaped tubular portion due to the formation of the flat portion remains as a cylindrical portion.

Due to the flow of metal by pressing to form the flat surface portion, the metal also flows at the boundary portion between the cylindrical portion and the flat surface portion, and a tapered portion in which the side peripheral wall gradually inclines toward the flat surface portion is formed. To. In addition, the force that presses the side peripheral wall inward to form the flat surface also affects the cylindrical portion, and the metal also flows slightly inward in the cylindrical portion, so that the cross section of the cylindrical portion is true. The degree of roundness decreases.

As a result of the examination, it was found that the roundness of the cross section of the cylindrical part can be increased so as to approach the original roundness by a simple process of pressing the tapered part in the axial direction. This is because the tapered portion is inclined, so that the component force of the force pressing the tapered portion in the axial direction acts in the direction of expanding the tapered portion in the radial direction, and this component force acts through the tapered portion. It was thought that it extended to the cylindrical part and the metal of the cylindrical part was allowed to flow outward.

Next, the press-molded product according to the present invention is
"It has a bottomed cylinder and
A cylindrical portion having a circular cross section, which is a cross section orthogonal to the axial direction,
A D-shaped tubular portion having a D-shaped cross section due to the formation of a flat portion located inside the cylindrical portion on a part of the side peripheral wall on the bottom side of the cylindrical portion.
It has a tapered portion that extends from the cylindrical portion to the D-shaped tubular portion and whose side peripheral wall is gradually inclined, and an axially depressed pressing mark is formed on the inner surface of the tapered portion. It has been ".

This is the structure of the press-molded product manufactured by the above-mentioned manufacturing method. The cross section of the cylindrical portion has a high roundness, and pressing marks due to punches remain as dents in the axial direction on the inner surface of the tapered portion.

As described above, according to the present invention, even if a flat surface portion is formed on a part of the side peripheral wall of the cylindrical portion, the cross-sectional circle of the remaining cylindrical portion has a high roundness. , And a press-molded product produced by the production method can be provided.

FIG. 1 (a) is a perspective view (a) of a press-molded product manufactured by the manufacturing method of one embodiment of the present invention, and FIG. 1 (b) shows a press-molded product in a direction different from that of FIG. 1 (a). 1 (c) is a perspective view of a press-molded product cut in the center in the axial direction, and FIG. 1 (d) is a cross-sectional view of the state of FIG. 1 (c). .. FIG. 2A is a schematic view of a process of drawing and forming a bottomed cylindrical workpiece from a metal flat plate, and FIG. 2B is a cross-sectional view illustrating a process of forming an intermediate workpiece having a D-shaped tubular portion. 2 (c) is a plan view of the intermediate work, and FIG. 2 (d) is a cross-sectional view of the intermediate work cut at the center in the axial direction. 3 (a) and 3 (b) are cross-sectional views illustrating a step of correcting the distortion of the cylindrical portion. 4 (a) to 4 (c) are roundness curves of the bottomed cylindrical work, the intermediate work, and the press-molded product after correcting the strain of the cylindrical portion, respectively.

Hereinafter, a manufacturing method according to an embodiment of the present invention will be described with reference to FIGS. 1 to 4.

The manufacturing method of the present embodiment includes a draw forming step of forming a bottomed cylindrical work 2 from a flat metal plate material 1 and a D forming an intermediate work 20 including a D-shaped tubular portion 22 from the bottomed cylindrical work 2. It includes a shape cylinder portion forming step and a correction step of correcting the distortion of the cylindrical portion 21 generated in the intermediate work 20 to obtain a press-molded product 200.

In the draw forming step, as shown briefly in FIG. 2A, the flat metal plate 1 to the bottomed cylindrical shape are passed through a plurality of steps of plastically deforming the metal using a punch and a die, respectively. Mold the work 2. In FIG. 2A, only two types of molded bodies whose shapes change from the metal plate material 1 to the bottomed cylindrical work 2 are shown, but in reality, seven steps are performed. The bottomed cylindrical work 2 is formed. The bottomed cylindrical work 2 has an opening 25 at one end of the cylindrical portion 21 and a bottom portion 26 at the other end, and has a flange portion 27 protruding outward from the peripheral edge of the opening 25.

In the D-shaped tubular portion forming step, as shown in FIG. 2B, a punch 41 and a die 42 are used to punch a part of the side peripheral wall on the bottom 26 side of the cylindrical portion 21 of the bottomed cylindrical work 2. A flat surface portion F is formed by applying an inward pressing force to a part of the side peripheral wall so as to be sandwiched between the flat surface portions of the 41 and the die 42. The side peripheral wall of the portion where the flat surface portion F is formed has a D-shaped cross section as shown in FIG. 2C, which is a cross section in a direction orthogonal to the axial direction, and this portion is D-shaped. The cylinder portion 22.

In the present embodiment, as shown in FIG. 2D, the flat surface portion F is formed so that the D-shaped tubular portion 22 is continuous with the bottom portion 26. The cylindrical portion 21 remains on the opening 25 side of the D-shaped tubular portion 22, but due to the flow of metal due to the pressing when forming the flat surface portion F, the metal also flows at the boundary portion between the cylindrical portion 21 and the flat surface portion F. A tapered portion 23 is formed in which the side peripheral wall is gradually inclined inward toward the flat surface portion F. As a result, an intermediate work 20 having a D-shaped tubular portion 22 on the bottom portion 26 side and a tapered portion 23 between the D-shaped tubular portion 22 and the cylindrical portion 21 can be obtained.

In the D-shaped tubular portion forming process, the force that presses the side peripheral wall inward to form the flat surface portion F also affects the cylindrical portion 21, and the cylindrical portion 21 also has a virtual extension of the flat surface portion F. The metal flows slightly closer to the surface. As a result, the shape of the cross section of the cylindrical portion 21 was close to a perfect circle before the D-shaped tubular portion molding step, but the roundness decreases after the D-shaped tubular portion molding step.

Therefore, after the D-shaped tubular portion forming step, a correction step for increasing the roundness of the cross-sectional shape of the cylindrical portion 21 is performed. In the correction step, as shown in FIGS. 3A and 3B, the tip of the punch 51 is brought to the cylindrical portion 21 while the intermediate work 20 is held by the die 52 in contact with the outer peripheral surface of the cylindrical portion 21. insert. The tip of the punch is a cylindrical portion 51e having an outer diameter slightly shorter than the inner diameter of the cross section of the cylindrical portion 21, and the cylindrical portion 51e is inserted into the cylindrical portion 21 and the cylindrical portion 51e is inserted in the axial direction of the cylindrical portion 21. Align the axial directions of and move forward.

Since the tapered portion 23 is inclined inward in the direction in which the punch 51 advances, the end portion of the cylindrical portion 51e comes into contact with the tapered portion 23 and presses the tapered portion 23 as the punch 51 advances. Since the tapered portion 23 is inclined, the component force of the force that the punch 51 presses the tapered portion 23 in the axial direction acts in the direction of expanding the tapered portion 23 in the radial direction. The component force acting on the tapered portion 23 thus extends to the cylindrical portion 21 via the tapered portion 23, and causes the metal of the cylindrical portion 21 to flow slightly outward in the radial direction.

That is, by forming the flat surface portion F, the metal flows inward to form the tapered portion 23, and along with this, the metal also flows inward in the cylindrical portion 21 to reduce the roundness of the cross section. On the other hand, an outward force in the opposite direction is applied to the tapered portion 23, and an outward force is also applied to the cylindrical portion 21 via the tapered portion 23. As a result, in the cylindrical portion 21, the metal flows outward at the portion where the metal flows inward to reduce the roundness of the cross section, so that the roundness of the cross section is formed in the D-shaped cylindrical portion. It is modified to approach the roundness before the process. Then, on the inner surface of the tapered portion 23, a pressing mark T, which is a depression of the mark pressed by the end portion of the cylindrical portion 51e of the punch, remains locally.

By the above manufacturing method, the press-molded product 200 as shown in FIGS. 1A to 1D can be obtained. That is, a cylindrical portion 21 having a bottomed tubular shape and a cross section orthogonal to the axial direction and a circular cross section, and a part of the side peripheral wall on the bottom 26 side of the cylindrical portion 21 and inside the cylindrical portion 21. The D-shaped cylindrical portion 22 having a D-shaped cross section due to the formation of the flat surface portion F, and the portion extending from the cylindrical portion 21 to the D-shaped tubular portion 22, the side peripheral walls are gradually inclined. The press-molded product 200 has a tapered portion 23 and has a pressing mark T recessed in the axial direction formed on the tapered portion 23.

Actually, the bottomed cylindrical work of the example, the intermediate work after the bottomed cylindrical work is subjected to the D-shaped tubular portion forming step, and the press-formed product after the intermediate work is subjected to the correction step are cylindrical. The roundness of the cross section of the part was measured. Specifically, a bottomed cylindrical work was formed from a metal plate material (SPC material) having a thickness of 2.3 mm. The size of the bottomed cylindrical work was such that the depth H from the edge of the opening to the inner peripheral surface of the bottom was about 29 mm, and the inner diameter of the cylindrical part was 11.55 mm. With respect to the inner peripheral surface of the cylindrical portion of the bottomed cylindrical work, the roundness of the cross-sectional circle was measured using a mounting table rotary roundness measuring machine according to JIS B7451. The roundness curve obtained as a result of the measurement is shown in FIG. 4 (a) (illustrated, thick solid line). Table by the difference between the radius R _max of the circumscribed circle (illustration, one-point chain line) of the roundness curve and the radius R _min of the inscribed circle (illustration, two-point chain line) of the roundness curve that shares the center with the circumscribed circle The resulting rotation accuracy (radial rotation accuracy) was 2.800 μm.

Similarly, the roundness of the cross-sectional circle on the inner peripheral surface of the cylindrical portion was measured for the intermediate work that had undergone the D-shaped tubular portion forming step. The axial length of the D-shaped tubular portion is about 1/3 of the depth H, and the axial length of the tapered portion formed with the formation of the flat surface portion F is about 1/7 of the depth H. It was. The roundness curve obtained as a result of the measurement is shown in FIG. 4 (b). The position in the axial direction in which the roundness was measured was the same as in the measurement for the bottomed cylindrical workpiece. The rotational accuracy (R _max −R _min ) in the radial direction is 7.740 μm, and it can be seen that the roundness of the cross section of the cylindrical portion is greatly reduced as the flat portion is formed. When the figure shown in FIG. 2B is likened to a clock, the plane portion is formed in the direction connecting 1 o'clock and 5 o'clock, and the roundness curve is distorted so that the circle is crushed in that direction. You can see that it is.

Similarly, the roundness of the cross section of the inner peripheral surface of the cylindrical portion was measured for the press-formed product after being subjected to the correction step of pressing the tapered portion of the intermediate work in the axial direction with a punch. The position in the axial direction in which the roundness was measured was the same as that in the measurement for the bottomed cylindrical work and the intermediate work. The roundness curve obtained as a result of the measurement is shown in FIG. 4 (c). The rotational accuracy (R _max −R _min ) in the radial direction was 3.584 μm, and it was confirmed that the roundness was considerably improved, although it did not return to the roundness before the flat surface was formed. ..

As described above, according to the manufacturing method of the present embodiment, the punch 51 punches the tapered portion 23 formed together when a part of the side peripheral wall of the cylindrical portion 21 is pressed from the outside to form the flat surface portion F. By an extremely simple process of pressing in the axial direction with, the distortion of the cylindrical portion 21 whose cross-sectional roundness has decreased due to the formation of the flat surface portion F is corrected, and the roundness is restored. Can be enhanced.

In the above embodiment, the case where the bottomed cylindrical work 2 has a flange portion 27 protruding outward from the peripheral edge of the opening 25 is illustrated. It has been confirmed that the distortion of the cylindrical portion in the D-shaped tubular portion forming step is smaller when the opening has a flange portion as described above, as compared with the case where the opening is a simple open end.

Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to the above embodiments, and as shown below, various improvements are made without departing from the gist of the present invention. And the design can be changed.

For example, in the above embodiment, the case where the D-shaped tubular portion 22 is formed so as to be continuous with the bottom portion 26 and the cylindrical portion 21 remains only on the opening 25 side in the D-shaped tubular portion molding step is illustrated. Not limited to this, the flat surface portion can be formed at a position where the cylindrical portion remains between the D-shaped tubular portion and the bottom portion. In this case, the tapered portion is formed not only on the opening side of the D-shaped tubular portion but also on the bottom side, but the tapered portion to be pressed by the punch is, of course, the tapered portion on the opening side. Even if there is a cylindrical portion on the bottom side of the D-shaped tubular portion, the cylindrical portion that requires high roundness is the cylindrical portion on the opening side, so that the cylindrical portion on the opening side is pressed by pressing the tapered portion on the opening side. It is enough to correct the distortion.

1 Metal plate 2 Bottomed cylindrical work 20 Intermediate work 21 Cylindrical part 22 D-shaped tubular part 23 Tapered part 25 Opening 26 Bottom part 27 Flange part 51 Punch (Punch used for correction to increase the roundness of the cylindrical part)
200 Press-molded product F Flat surface T Press marks

Claims (2)

A cross section that is orthogonal to the axial direction by forming a flat surface on a part of the side peripheral wall on the bottom side of the cylindrical portion of the bottomed cylindrical workpiece by press molding that applies a force to press inward. An intermediate portion having a D-shaped tubular portion having a D-shape, a remaining cylindrical portion, and a tapered portion that extends from the cylindrical portion to the D-shaped tubular portion and whose side peripheral wall is gradually inclined. Mold the work and
By inserting a punch through the opening of the intermediate work and pressing the tapered portion in the axial direction of the cylindrical portion, the strain generated in the cylindrical portion during the formation of the D-shaped tubular portion is corrected, and the above-mentioned A method for manufacturing a press-molded product, which comprises increasing the roundness of the cross section of a cylindrical portion. It has a bottomed cylinder and
A cylindrical portion having a circular cross section, which is a cross section orthogonal to the axial direction,
A D-shaped tubular portion having a D-shaped cross section due to the formation of a flat portion located inside the cylindrical portion on a part of the side peripheral wall on the bottom side of the cylindrical portion.
It has a tapered portion that extends from the cylindrical portion to the D-shaped tubular portion and whose side peripheral wall is gradually inclined, and an axially depressed pressing mark is formed on the inner surface of the tapered portion. A press-molded product characterized by being made.

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