JP4879596B2 - Method for producing metal member having through hole - Google Patents

Description

In the present invention, for example, a bulging portion is formed in a middle portion in the axial direction of a hollow tubular material by a hydroforming method, and then a through hole is formed in a side wall portion of the bulging portion. It can be used as a method for manufacturing a steering column . Or after processing the metal plate which comprises the body for motor vehicles by the hydroforming method, it can utilize also when forming the attachment hole for mounting | wearing with a door knob, a direction indicator, etc. in a part of this metal plate.
In short, the metal member that is the target of the manufacturing method of the present invention includes a metal plate member, and the portion in which the through hole is formed is a plate shape (including a flat plate shape and a curved plate shape). Say the member. A metal plate member formed by processing a flat metal plate includes, of course, a metal tube having a through-hole formed in a tube wall portion, such as an electric sewing tube or an extruded tube.

  Among the steering columns that make up the steering system for automobiles, an intermediate portion in the axial direction of the steering column incorporated in a steering wheel height position adjusting device called a tilt type steering device, or a steering wheel longitudinal position adjusting device called a telescopic steering device It is necessary to fix a bracket called a column bracket. Conventionally, generally, such a column bracket formed separately from the steering column is welded and fixed to the steering column later. On the other hand, in Patent Document 1, as shown in FIGS. 15 to 16, the axial intermediate portion of the metal hollow tube constituting the steering column 1 is inflated radially outward, and this inflated portion is the column. A structure for the bracket 2 is described. By adopting such a structure, it is possible to realize a light and inexpensive steering apparatus for an automobile with a small number of parts.

In order to manufacture the steering column 1 integrally provided with the column bracket 2 as described above, the inner peripheral surface of the metal tube 3 (made of steel plate or aluminum alloy) constituting the steering column 1 by a hydroforming method. A hydraulic pressure (e.g., water pressure) is applied to the metal tube 3 so that a part of the metal tube 3 is bulged outward (plastic deformation) as shown in FIGS. In addition, in order to bulge the axial direction intermediate part of the said metal pipe 3 by the said hydroform construction method, as shown, for example in FIG. 19 mentioned later, the outer surface shape of the said metal pipe 3 which can be divided | segmented and should be expanded and manufactured. A hollow member 11 (metal tube), which is a material, is set in a mold 6 having an inner surface shape suitable for the above. Then, both ends of the hollow member 11 are closed with shaft pressing tools 19a and 19b, and a high hydraulic pressure of about 196 MPa (2000 kg / cm ² ) is applied to the hollow member 11, for example. By applying this hydraulic pressure, the axially intermediate portion of the hollow member 11 is expanded radially outwardly until it is in close contact with the inner surface of the cavity of the mold 6, and bulges to the axially intermediate portion of the hollow member 11. Part 7 is formed. At this time, in order to prevent the bulging portion 7 from becoming thin, the hollow member 11 is compressed in the axial direction by the biaxial pushing tools 19a and 19b, and the material supply to the bulging portion 7 is promoted. .

Note that the portion bulged as described above may be further bulged as shown in FIGS. 18A to 18B. In this manner, the column bracket 2 formed in a part of the steering column 1 needs to have through holes 5 and 5 for inserting, for example, the tilt bolt 4. The through holes 5 and 5 must be formed after the column bracket 2 is formed by plastic deformation of a part of the metal tube 3. Further, when configuring a telescopic steering device, the through holes 5 and 5 need to be long holes in the axial direction of the steering column 1.
Conventionally, as a technique for forming a through hole in a portion of the hollow member that has been expanded by the hydroform method, hydropiercing as described in Patent Documents 2 to 3 and Non-Patent Document 1 etc. It has been known. Of these, three examples of the prior art described in Non-Patent Document 1 will be described with reference to FIG.

  First, in the case of the first example shown at the left end of FIG. 19, after the step of forming the bulging portion 7 by inflating the material placed in the mold 6 by the hydroform method, the bulging is completed. While the hydraulic pressure is applied to the inside of the portion 7, the tip surface is fitted in the cylinder hole 8 provided at a position aligned with the portion where the through hole 5 is to be formed in a part of the mold 6 and the bulging portion 7 is pressed against the bulging portion 7. A part of the bulging portion 7 is punched out by the punch 9 to form the through hole 5. The punched piece 10 produced by punching a part of the bulging portion 7 with the punch 9 remains inside the hollow member 11 provided with the bulging portion 7.

  Next, in the case of the second example shown in the center part of FIG. 19, after the step of forming the bulging part 7 by inflating the material installed in the mold 6 by the hydroforming method is completed, With the hydraulic pressure applied to the inside of the portion 7, the tip surface is inclined in one direction, fitted in the cylinder hole 8a provided at a position aligned with the portion where the through hole 5a is to be formed in a part of the mold 6 The punch 9a is pressed against the bulging portion 7. And this punch 9a breaks through a part of this bulging part 7, and it is set as the said through-hole 5a. Since the shearing or breaking for breaking the side wall of the bulging portion 7 to form the through hole 5a starts from one side of the through hole 5a and progresses gradually toward the other side, the processing of the through hole 5a is performed. The punched piece 10a generated along with this remains in a state of being connected to the side wall of the bulging portion 7 even after the processing of the through hole 5a is completed.

  Furthermore, in the case of the third example shown in the right end portion of FIG. 19, after the step of forming the bulging portion 7 by inflating the material installed in the mold 6 by the hydroform method, the bulging portion is completed. The slide tool 13 fitted in the punched hole 12 provided at a position aligned with the portion where the through hole 5b is to be formed in a part of the mold 6 while the hydraulic pressure is applied to the inside of the mold 7 is Move in a direction away from 7. As a result, the front end surface of the slide tool 13 and the outer surface of the bulging portion 7 that have been in contact with each other are separated from each other. Since the fluid pressure continues to be applied to the inner surface of the bulging portion 7, a portion of the side wall of the bulging portion 7 that is aligned with the punched hole 12 is removed as the backup is lost. The hole 5b is formed by being strongly pushed into the hole 12 and shearing or breaking. The punched piece 10b generated as a result is collected in the punched hole 12, and is removed by advancing the slide tool 13 before the next processing.

  Of the three prior arts described in Non-Patent Document 1 as described above, according to the first example shown at the left end of FIG. 19, the punched piece 10 generated when the through hole 5 is formed. Remains in the hollow member 11. For this reason, it is necessary to take out the punched piece 10 from the hollow member 11 after forming the through hole 5. However, when the end opening of the hollow member 11 is narrower than the size of the punched piece 10 or the hollow member 11 has a complicated shape, the inside of the hollow member 11 is removed. It may be impossible or difficult to take out the punched piece 10. Further, in the case of the first example, the outer surface of the bulging portion 7 is strongly pressed by the punch 9 in order to form the through hole 5. A peripheral portion of the through hole 5 is deformed (slipped) inward in the radial direction of the hollow member 11. For this reason, it becomes difficult to ensure the shape accuracy and dimensional accuracy of the surrounding portion after the processing is completed.

  Next, according to the second example shown in the center portion of FIG. 19, it is difficult to accurately regulate the shape and dimensions of the processed through-hole 5a as desired. In particular, one end of the through hole 5a (the left end in FIG. 19) is a part of the side wall of the bulging portion 7 where the base end of the punched piece 10a is connected. In order to remain as it is, the side wall is bent and deformed by the amount of bending deformation. On the other hand, in the middle part through the other end part (the right end part in FIG. 19) of the through hole 5a, the side wall is strongly pushed inward in the radial direction by the punch 9a, so Transforms into As a result, it is difficult to ensure the accuracy regarding the shape and size of the through hole 5a in any part. Further, since the punched piece 10a remains in a state of projecting radially inward from the inner surface of the bulging portion 7, the punched piece 10a may become an obstacle depending on the use of the hollow member 11.

In consideration of these matters, it is preferable to form the through hole 5b in the bulging portion 7 of the hollow member 11 according to the third example shown in the right end portion of FIG. In view of such circumstances, the method previously considered for manufacturing the steering column 1 integrally provided with the column bracket 2 as shown in FIG. 15 will be described with reference to FIGS. In the method considered above, first, as shown in FIG. 20, a metal tube 3 which is a material and has a plate thickness of T ₁ is arranged at a predetermined position in the mold 6a. As shown in FIG. 21, the mold 6 a is formed by a pair of mold elements 15, 15 being abutted in the middle, and the inside of the metal tube 3 includes both ends and an intermediate portion. The circumferential hole half 16 can be fitted with almost no gap, and the recess 17 protrudes radially outward from the middle of the circular hole 16. The inner surface shape of the concave portion 17 matches the outer surface shape of the bulging portion 7 to be formed. Further, in a part of both the mold elements 15 and 15, they are shifted from the central axis of the circular hole portion 16 toward the concave portion 17 and radially outward of the circular hole portion 16, and are aligned with each other. Holes 12a and 12a are provided respectively. The slide tools 13a and 13a are tightly fitted in the punched holes 12a and 12a so that the slide tools 13a and 13a can advance and retreat with respect to the concave portion 17, respectively.

  When making the steering column 1 with the column bracket 2 integrally provided, first, as shown in FIGS. 20 to 21, the metal tube 3 is sandwiched between the mold elements 15, 15. The metal tube 3 is fitted into the circular hole portion 16. In this state, the circumferential half piece of the intermediate portion of the metal tube 3 faces the concave portion 17. Next, hydraulic pressure (generally water pressure) is introduced to the inside of the metal tube 3 while pressing both end edges in the axial direction of the metal tube 3 in directions approaching each other by the axial pressing tools 19 and 19. The introduction of the hydraulic pressure is performed, for example, through the center holes 18 and 18 of one or both axial pushing tools 19 and 19. Further, in the initial stage of the introduction of the hydraulic pressure performed in this way, the front end surfaces 20 and 20 of the slide tools 13a and 13a and the inner surface of the recess 17 are made to coincide.

  In this way, when the hydraulic pressure is introduced into the inside of the metal tube 3 and the biaxial pushing tools 19 and 19 are moved in a direction approaching each other, a circumferential piece at an axially intermediate portion of the metal tube 3 is obtained. A half portion bulges toward the concave portion 17. That is, by applying a force that compresses the metal tube 3 in the axial direction while applying a strong force directed radially outward to the inner peripheral surface of the metal tube 3, the metal tube 3 is formed as shown in FIG. As shown in FIG. 23, it is processed into a shape along the inner surface shape of the mold 6a, that is, a shape having a bulging portion 7a projecting radially outward in a circumferential half piece of the intermediate portion.

  If the slide tools 13a and 13a are retracted from the side walls 14 and 14 of the bulging portion 7a immediately after being formed from the state in which the bulging portion 7a is formed in this way, the both side walls 14 and 14 are formed. A part of which is aligned with the two holes 12a and 12a is pushed into the holes 12a and 12a by the hydraulic pressure existing inside the bulging part 7a, and is inserted into the holes. 5c and 5c are formed.

  As described above, if the technology for forming the bulging portion 7a in a part of the metal tube 3 by the hydroforming method is combined with the third example of the prior art shown in the right end portion of FIG. It is considered that there is a possibility that the through holes 5c and 5c can be efficiently formed in a part of the bulging portion 7a. However, the present inventors have found that the through-holes 5c and 5c cannot always be stably formed by simply combining the two techniques. This cause will be described with reference to FIGS.

When the bulging portion 7a is formed on a part of the metal tube 3 by the hydroform method, the metal plate constituting the metal tube 3 is stretched in the surface direction at a portion corresponding to the bulging portion 7a. Although the metal tube 3 is compressed in the axial direction to promote the supply of material to the bulging portion 7a, the metal plate becomes smaller than the original plate thickness T ₁ (see FIG. 20). And the extent to which the plate thickness is reduced in this way also makes a difference in the bulging portion 7a. Specifically, since the supply amount of the material decreases as the distance from the base of the bulging portion 7a (the lower part of FIGS. 22 to 23) decreases, the thickness of the portion closer to the base is small, and the tip (see FIG. The extent to which the plate thickness decreases as it goes to the upper part of 22 to 23) becomes remarkable. Further, even in this tip portion, the curvature becomes large (the radius of curvature becomes small), and the left and right corner portions and the vicinity thereof in FIG.

And the plate | board thickness of the part which should form both the said through-holes 5c and 5c among the said both-side walls 14 and 14 is not uniform regarding the width direction (up-down direction of FIGS. 22-25) of these both through-holes 5c and 5c. (Gradual change). Specifically, the cross-sectional shape of the part where both the through holes 5c and 5c are to be formed in the both side walls 14 and 14 is a wedge shape. Then, the plate thickness T _2, T ₃ of the side walls 14, 14 of these Ryotsuana 5c, in both widthwise end edges of 5c (see FIG. 24) is greater at the proximal end side of the said bulging portion 7a, Similarly, it becomes smaller near the tip (T ₂ > T ₃ ).

When the bulging portion 7a is formed, a pressure increase pattern of the hydraulic pressure introduced into the metal tube 3 and a pattern (axis pressing pattern) for moving the shaft pressing tools 19, 19 are appropriately set. . That is, when the hydraulic pressure rises quickly with respect to the increase in the amount of axial push, the bulge portion becomes extremely thin and the possibility of cracking increases. On the other hand, when the increase in the axial push amount precedes the increase in the hydraulic pressure, the material is likely to buckle. In general, when the axial push is preceded in a range where buckling does not occur and the final axial push amount is set to be large, the difference between the thicknesses T ₂ and T ₃ at the both end edge portions is reduced. In addition, the difference from the original plate thickness T ₁ can be reduced. When the normal processing method described in Non-Patent Document 1 is adopted as the outside hydropiercing shown in the right end part of FIG. 19, among the plate thicknesses T ₁ , T ₂ , T ₃ of the above-mentioned parts The difference between the plate thicknesses T ₂ and T ₃ of the both edge portions is within 5%, more preferably within 3% when viewed from the side where the plate thickness is large, forming the through holes 5c and 5c. It is preferable from the aspect of doing. However, when the asymmetry of the product shape is significant, even if the shaft pressing pattern or the hydraulic pressure increasing pattern is adjusted, the uneven thickness cannot be sufficiently eliminated. As shown, when the bulging portion 7a is formed only on one side of the metal tube 3, the thickness of the side walls 14 and 14 where the through holes 5c and 5c are to be formed is in a non-uniform state as described above. . In other words, the difference between the plate thicknesses T ₂ and T ₃ of the both end edge portions may exceed 3% and further 5% when viewed from the side where the plate thickness is large.

  As shown in FIGS. 21, 23 to 25, the end surfaces 20, 20 are formed on both side walls, although the thickness of the side walls 14, 14 where the through holes 5 c, 5 c are to be formed is not uniform. When the slide tools 13a and 13a, which are flat surfaces parallel to 14 and 14, are used, it is difficult to stably form the through holes 5c and 5c. That is, when the slide tools 13a and 13a having the simple shapes of the front end surfaces 20 and 20 as described above are used, the shape of the through hole is complicated such as an ellipse or an oval, or a simple circular hole. However, when processing a through hole with a large opening area, the punched piece cannot be completely removed from the portion that should be the through hole, and the punched piece remains in a state of being partially connected to the material. easy. In particular, when the through holes are formed in a portion having a non-uniform thickness, as in the case where the through holes 5c and 5c are formed in the side walls 14 and 14, the above-described problems are likely to occur.

That is, the through-hole 5c is formed by the slide tool 13a having the flat tip end surface 20 as described above, despite the fact that there is a difference exceeding 5% in the plate thicknesses T ₂ and T ₃ of the both end edge portions. When trying to do so, almost simultaneously with the slide tool 13a starting to retract, a portion of the side wall 14 facing the punch hole 12a starts to deform (shear) into the punch hole 12a. Then, when the slide tool 13a is retracted to some extent, the plate thickness T ₃ is small part of the portion facing the vent hole 12a in part of the side wall 14, also on part thickness T ₂ greater Fracture first. As a result, as shown in FIG. 25, both sides of the portion to be extracted while the portion having a large plate thickness T ₂ in the portion of the side wall 14 facing the punch hole 12 a is connected to the side wall 14. In addition, the same hydraulic pressure exists. That is, the hydraulic pressure inside the metal tube 3 is released from the broken portion. As a result, even more much retract the slide tool 13a, shear portion where the plate thickness T ₂ is connected to the larger the side wall 14 does not proceed, it becomes impossible to form the through hole 5c. As described above, the phenomenon that a part of the portion to be removed remains connected to the side wall 14 is that the difference in the thickness of the portion where the through hole is to be formed is larger, and the shape of the through hole is a round hole. As the shape of the long hole is more complicated than in the case of the above, the more complicated the shape becomes, the more remarkable it becomes.

In the case of conventionally known hydropiercing as shown in FIG. 19 described above, the bulging portion 7 has a symmetric (or almost symmetrical) shape with respect to the central axis of the hollow member 11, and the through hole Since the wall thickness of the tube wall of the portion to be formed is substantially uniform over the entire circumference, the through-hole can be formed even in the case of so-called outside extraction in which the portion to be extracted is taken out radially outward. However, in the case of the column bracket 2 of the steering column 1, as described above, it is difficult to make the wall thickness of the tube wall where the through hole should be formed uniform. Further, in the case of the drilling method described in the left part and the center part of FIG. 19, even if the thickness of the part where the through hole is to be formed is not uniform, the formation of this through hole is possible. There are problems as described above.
In addition, the method described in the said patent documents 2 and 3 cannot avoid that the whole process is complicated and cost increases. Therefore, it is not a substitute for a method of reducing the cost by continuously and efficiently performing the processing of the bulging portion 7a and the forming operation of the through holes 5c and 5c as shown in FIGS.

Japanese Patent Laid-Open No. 8-276852 JP-A-6-292929 JP 2001-314926 A Frank-Ulrich LEITLOFF / Steffen GEISWEID, “Application of tube hydroforming technology in the automotive industry”, Journal of the JSTP vol.39 no.453 (1998-10)

In view of the circumstances as described above, the present invention is a part of a member that is made of metal and at least a part of which is plate-shaped, and the thickness of the plate-shaped part is different. The present invention was invented to realize a manufacturing method capable of stably and inexpensively performing the operation of forming a through hole in a part.

The metal member having a through hole which is the object of the manufacturing method of the present invention is a part of a member made of metal and at least part of which is plate-shaped, and there is a difference in the thickness of the plate-shaped part. A through-hole is provided in a certain thickness nonuniform portion so as to penetrate this portion.
This through hole applies the hydraulic pressure to the other surface of the non-uniform thickness portion in a state where one surface of the non-uniform thickness portion is in contact with the mold, while the part of the non-uniform thickness portion It is formed by hydropiercing, in which a portion corresponding to a hole provided in the mold is pushed into this hole.
This hydropiercing is performed by simultaneously terminating the shearing phenomenon on the entire periphery of the through hole to be formed .

For this reason, in the case of the invention described in claim 1, as a slide tool to be inserted into vent hole of the mold, depending on the thickness distribution of the material to be subjected to shearing, the front end surface, the thickness A slide tool having a shape that protrudes toward the inner side of the mold on the smaller side and is recessed toward the outer side of the mold on the larger thickness side is used. Then, as in the invention described in claim 4, while applying the hydraulic pressure to the other surface of the non-uniform thickness portion in a state where the inner surface of the mold is abutted against one surface of the non-uniform thickness portion, The slide tool is displaced in the direction of retracting from the uneven thickness portion, and a portion of the uneven thickness portion corresponding to the punch hole is pushed into the punch hole by the hydraulic pressure.
Alternatively, as in the invention described in claim 2, the radius of curvature of the cross-sectional shape of the cutting edge portion is a peripheral portion of the mold vent holes, depending on the thickness distribution of the material the cutting part is subjected to shearing Thus, a mold that is small on the thick side and large on the thin side is used.
Furthermore, like the invention described in claim 3, the invention described in claim 1 and the invention described in claim 2 can be carried out simultaneously.
In any case, a shear stress is generated in a portion corresponding to the entire peripheral edge of the punched hole in the uneven thickness portion, a shear phenomenon is generated in this portion, and this shear phenomenon is simultaneously combined with fracture. The through hole is formed in a portion aligned with the punched hole.

  This point will be described with reference to FIG. 1A to 1C are shearing processes by hydropiercing, and through holes are formed in a part of a plate-like part (hereinafter referred to as “metal plate 25”) by a part of a metal member. It is sectional drawing which shows the state to do in steps. The so-called outer-piercing hydropiercing described above is basically a shearing process by a blade edge part which is a peripheral part of the punching hole 12 provided in the mold 6. It is as follows. First, as shown in FIG. 1A, when the slide tool 13 starts to move outward from the punching hole 12 of the mold 6, a part of the metal plate 25 is formed in the recess generated by the retraction of the slide tool 13. Enters, and this part is plastically deformed into a convex shape.

  Even after the plastic deformation occurs, if the slide tool 13 continues to move (retract), the metal edge is formed by the cutting edge portion 26 provided at the peripheral edge of the punching hole 12 as shown in FIG. A shearing surface 27 starts to be formed on a part of one surface (outer surface, right surface in FIG. 1) of the plate 25. Then, at a stage where the processing of the shearing surface 27 has progressed to some extent, as shown in FIG. 1C, the cracks 28 (cracks) generated from the shearing surface 27 are transferred to the other surface of the metal plate 25 ( The metal plate 25 penetrating to the left side in FIG. 1 and remaining uncut is instantaneously broken, and the shearing process is completed. The resulting punched piece 10 is discharged to one side of the metal plate 25. On the outer surface of the metal plate 25, that is, the surface of the product, as shown in FIG.

As described above, the shearing process by external hydropiercing is a combination of plastic deformation, shearing process, and fracture. In the case of the present invention, the timing of starting shearing process is the thickness distribution. Regardless of the thickness distribution, through holes can be formed by the above-described hydropiercing. In the claims and specification of the present case, the time point at which the formation of the shearing surface 27 shown in FIG. 1B starts is referred to as “shearing start timing”, and the crack 28 shown in FIG. The time when the metal plate 25 penetrates in the thickness direction and the fracture is completed and the material is completely separated is defined as “crack generation timing leading to fracture” (shearing phenomenon termination timing).

  In order to form a through hole in the non-uniform thickness portion of the metal plate 25 in the present invention as described above, the outside hydro-hydrophone as shown in the right end of FIG. When the piercing is performed without any special measures, the shearing phenomenon is terminated first at the thinnest portion around the through hole to be formed, and the crack 28 is formed in the thickness direction of the metal plate 25 at this portion. To penetrate. By the end of the local shearing phenomenon, as described with reference to FIG. 25, the pressure loss occurs, the subsequent shearing process does not proceed, and the uncut portion as shown in FIG. 25 occurs. For this reason, conventionally, as described above, in order to form a through hole in a non-uniform thickness portion, it has not been possible to apply external hydropiercing. On the other hand, in the case of the present invention, even in the non-uniform thickness portion, the shearing start timing is changed according to the thickness distribution, so the shear phenomenon in the small thickness portion is partially broken. Thus, it is possible to avoid a situation in which the shearing phenomenon of the portion having the small thickness is clearly ended earlier than the portion having the large thickness. Specifically, in the portion where the wall thickness is large compared to the portion where the wall thickness is small, for example, the start timing of the shearing process is advanced, and the shearing process is completed and the fracture occurs at the portion where the wall thickness is small and the portion where the wall thickness is large. Align the timing of the cracks to reach (the last break is generated all around the hole at the same time). That is, it is possible to achieve complete outer piercing hydropiercing with no uncut portions by aligning the timing of the end of the shearing phenomenon on the entire circumference of the through-hole to be formed.

  An advantage of carrying out the present invention as described above is that it is not always necessary to strictly control the timing of starting the shearing process according to the thickness distribution. That is, when the through hole is formed, the last of the shearing phenomenon that occurs in the portion corresponding to the peripheral portion of the through hole is a break due to the penetration of the crack, and this break is to some extent at the peripheral portion of the through hole. If the shearing phenomenon progresses, it propagates along this peripheral edge. Therefore, the timing of the progress of the shearing phenomenon is set so that the remaining amount of the shearing allowance is aligned with a certain degree of accuracy (the moment when the crack is generated in a part, the shearing is proceeding to some extent in the remaining part). If adjusted, the timing of the end of the shearing phenomenon (crack generation) is practically aligned. In other words, it is sufficient to adjust the timing of the shearing process so that the breakage occurs at the periphery of the through-hole at the same time over the entire circumference. Moreover, since the adjustment of this timing can be performed relatively easily, for example, by changing the shape of the tip surface of the slide tool, the adjustment of the timing of the shearing start is from the surface that aligns the timing of occurrence of the crack, This is a very realistic measure.

In addition, even if the timing of starting shearing is the same for all circumferences, the timing of crack generation leading to fracture is adjusted according to the thickness distribution at the periphery of the through-hole to be formed. Similarly, if a break due to a crack is generated earlier than a small portion, the break can be completed simultaneously over the entire circumference. That is, by adjusting the timing of crack generation leading to breakage according to the thickness distribution of the metal plate, it is possible to align the timing of the end of the shearing phenomenon on the entire periphery of the through hole to be formed, External piercing is possible. This measure is possible, for example, by modifying the mold side, specifically, by changing the radius of curvature of the cross-sectional shape of the blade edge portion, which is the peripheral edge of the punch hole of the mold, as in the invention described in claim 2. It is. In other words, the radius of curvature of the cross-sectional shape of the cutting edge portion is a mold that is small on the thick side and large on the thin side according to the thickness distribution of the material to be sheared. However, the occurrence of breakage due to cracks is delayed on the small thickness side. In this way, it is possible to align the timing of the end of the shearing phenomenon (crack generation) without adjusting the timing of starting the shearing process. In addition, as in the first aspect of the invention described above, it is also possible to align the timing of the end of the shearing phenomenon by combining the idea of the shape of the tip of the slide tool and the idea of the radius of curvature of the edge part described above. It is.

  Note that the technique for generating the above breaks simultaneously all around the tip of the former slide tool by combining the adjustment of the timing for starting shearing and the adjustment of the timing for generating cracks ends the shearing phenomenon. Align the timing. On the other hand, the latter technique of generating the rupture at the same time around the entire circumference by devising the radius of curvature of the cutting edge portion aligns the timing of the end of the shearing phenomenon mainly by adjusting the timing of the occurrence of cracks leading to the rupture. Therefore, the tool is designed according to the thickness distribution of the material so that the timing difference necessary for simultaneously terminating the shearing phenomenon can be obtained over the entire length of the peripheral edge of the through hole to be formed. For example, in order to delay the start timing of shearing in a thin part, a compressive stress in a direction perpendicular to the shearing surface is applied to this part in the initial stage of processing, or the edge part of the hole ( Increase the radius of curvature of the cutting edge. On the other hand, in order to accelerate the shear start timing in the thick part, the shear start itself is accelerated, or a tensile stress is applied to this part in the initial stage of processing.

A metal member having a through-hole, which is an object of the production method of the present invention, is generally a tubular member having a closed cross section because it is appropriate to be combined with a hydroforming method (hydroforming). It may be a plate-like member, and its shape is not particularly limited. In the case of a tubular member, either an electric sewing tube or a seamless tube (including an extruded tube) may be used. Moreover, the part which should form a through-hole among plate-shaped members is not restricted to a flat part, A curved part may be sufficient. For example, hydroforming and hydropiercing can be applied to a flat plate or a curved plate such as a car body. In such a case, after forming a flat plate or a curved plate, a through hole can be formed as it is, so that the machining process can be simplified. A metal member having a representative through hole is, for example, an outer tube for a steering column having an integrated column bracket, and the integrated column bracket is formed by, for example, hydroforming. In addition, the non-uniform thickness portion of the metal member with a through hole refers to a portion with a difference in thickness, but not only when the thickness changes continuously but also changes stepwise. , And those that change continuously and stepwise (a portion that changes continuously and a portion that changes stepwise are mixed).

  The thickness change rate (difference between the minimum thickness and the maximum thickness) at the portion (thickness nonuniformity portion) where the through hole is to be formed in the metal member is not particularly limited. The present invention is effective regardless of the rate of change. However, in consideration of the fact that the larger the change rate of the wall thickness, the more difficult it is to form through holes by general external hydropiercing, the greater the change rate of the wall thickness, the greater the effectiveness of the present invention. Become. That is, it is effective to implement the present invention when the content is 3% or more, and further effective when the content is 5% or more.

  The uneven thickness portion is formed due to various factors. It occurs not only in the formation of the bulging portion by hydroforming as described above, but also in other plastic processing such as drawing and bending. Furthermore, since it may occur in other than plastic working, the factor causing the uneven thickness portion is not limited when defining the technical scope of the present invention. Similarly, the shape of the uneven thickness portion is not particularly limited as described above. For example, when a pipe is bent, the outer peripheral side of the bend is thinned, the inner peripheral side of the bend is increased, and a thickness difference is generated. Even when a hydroformed process is performed on the material subjected to the bending process to form a flat portion, a difference in thickness occurs as a result. The present invention is also effective when a through hole is formed on a flat surface or a curved surface in which a difference in thickness occurs due to such a cause. Further, the type of metal is not particularly limited. Of course, non-ferrous alloys such as iron-based alloys such as steel, aluminum-based alloys, copper-based alloys, and other various metals and alloys may be used.

According to the method of manufacturing a metal member having a through hole of the present invention configured as described above, a part of a member made of metal and having at least a part in a plate shape, The operation of forming the through hole in the uneven thickness portion having a difference in thickness can be performed stably and at low cost.
That is, even when the thickness of a part of the plate-shaped member is not uniform by devising the shape of the tip surface of the slide tool or the shape of the peripheral edge of the punch hole in the mold. The difference in plate thickness between the side edges of the punched hole can be eliminated or reduced. For this reason, as the slide tool is retracted from the non-uniform thickness portion, the portion of the non-uniform thickness portion that opposes the punch hole is torn around the entire circumference of the punch hole. Thus, the through hole can be reliably formed.

When carrying out the invention described in claim 1 of the present invention, for example, as in the invention described in claim 5 , the most protruding portion of the tip surface of the slide tool coincides with the inner surface of the mold. It is located in the part to be. Then, the front end surface is brought into contact with one surface of the non-uniform thickness portion on the side where the plate thickness is small among the non-uniform thickness portions, and is opposed to the large side via a gap. The through hole is formed by displacing the slide tool from this state in a direction in which the slide tool is retracted from the uneven thickness portion inside the punch hole.

  When configured in this way, in the state before the slide tool is retracted (the most protruding portion of the tip surface of the slide tool is located at a portion that coincides with the inner surface of the mold), A part of the non-uniform thickness part that opposes the gap, that is, the part on the side where the plate thickness is larger is slightly pushed into the gap. As a result, the shearing process is started earlier than the other portions at the portion of the portion on the side where the plate thickness is larger that contacts the one end edge of the opening of the punch hole. At the same time, the plate thickness of this portion is slightly reduced, and the difference between the plate thickness of this portion and the plate thickness of the portion facing the other end edge of the opening of the punched hole in the side portion where the plate thickness is small, Reduce or eliminate. Therefore, if the slide tool is retracted from this state, shearing is started also in the other portions. Then, a portion of the uneven thickness portion that faces the punched hole is broken over the entire circumference of the periphery of the opening of the punched hole and pushed into the punched hole to form the through hole. .

Alternatively, as in the invention described in claim 6 , the most protruding portion of the tip surface of the slide tool is protruded from the inner surface of the mold, and the least protruding portion is coincident with the inner surface or more than the inner surface. Locate in the recessed part. With the tip of the slide tool arranged at such a position, the wall thickness is applied to the surface opposite to the surface facing the slide tool on one side of the uneven thickness portion. The uneven portion is bent following the tip of the slide tool. In this state, the tip surface of the slide tool comes into contact with one surface of the uneven thickness portion bent in this manner. From this state, the thickness of the slide tool is increased inside the punch hole. A through hole is formed by displacing in a direction to retract from the uniform portion.

  In such a configuration, by applying hydraulic pressure to one surface of the uneven thickness portion, portions corresponding to both end edges of the portion where the through hole should be formed in a portion of the uneven thickness portion. Of these, the portion on the side where the plate thickness is reduced is deformed relatively greatly in the direction opposite to the direction of deformation when the slide tool is retracted to form the through hole. On the other hand, the portion having a relatively large plate thickness does not deform in the direction opposite to the direction in which the through hole is formed, or even if it is deformed, the amount of deformation remains small.

  In accordance with the plate thickness of the part corresponding to both end edges of the part where the through hole should be formed in a part of the uneven thickness part, the slide tool is changed from the state in which the shape of both parts is as described above. Is retracted from the uneven thickness portion in the punched hole, a portion of the uneven thickness portion that matches the punched hole is pushed into the punched hole. At this time, the portion having a relatively large plate thickness immediately starts to be pushed into the punched hole and shearing is started, whereas the portion having the small plate thickness is once parallel to other portions. After being deformed, it is pushed into the punched hole. Then, the part where the thickness is reduced is deformed until it becomes parallel with the other part once, and further, in the process of being pushed into the punched hole, a compressive stress is applied to this part, and this part is difficult to break. (Breaking timing is delayed). In addition, the thickness of this portion slightly increases.

  For this reason, there is no significant difference between the timing from the start of shearing to breakage at the portion where the plate thickness is relatively large and the timing from the start of shearing to breaking at the portion where the plate thickness is reduced. . As a result, the portion of the non-uniform thickness portion that opposes the punched hole is pushed into the punched hole while simultaneously breaking along the entire periphery of the punched hole. It is formed.

When practicing the present invention, as in the invention described in claim 7 , for example, a part of the material whose thickness is gradually changed in a part of the uneven thickness part is expanded by a hydroforming method. As a side wall of the bulging part.
In this case, for example, as in the invention described in claim 8 , the metal member is inflated radially outward by a hydroforming method and a part of the hollow tube is inflated on the side wall of the bulging portion. The steering column has a through hole. Then, the through hole is formed following the processing of the bulging portion.
If the present invention is carried out in such a form, the formation of the bulging portion and the formation of the through hole can be performed continuously without changing the material, and the manufacturing cost can be reduced by simplifying the process. I can plan.
Further, in this case, for example, as described in claim 9, when considering a virtual plane including the central axis of the hollow tube and extending in a direction perpendicular to the direction in which the bulging portion bulges, Is formed at a position deviating from the virtual plane in the bulging direction.
Among the side wall portions constituting the bulging portion, the thickness of the portion existing at such a position gradually changes. For this reason, it is effective to form a through hole in the side wall portion according to the present invention.

2 to 5 show Embodiment 1 of the present invention corresponding to claims 1, 4 , 5, and 7-9 . The present embodiment is characterized in that a part of the metal tube 3 is plastically deformed radially outward by the hydroforming method as shown in FIGS. 20 to 23 as shown in FIGS. After forming the bulging portion 7a, the step of forming the through hole 5c in the side wall 14 of the bulging portion 7a is devised so that the through hole 5c can be reliably formed. Since the point of forming the bulging portion 7a is as described above, overlapping description will be omitted or simplified, and the following description will focus on the features of the present embodiment.

  Also in the case of the present embodiment, a part of the mold element 15 constituting the mold 6a corresponds to the through hole 5c in the portion of the side wall 14 where the through hole 5c is to be formed (substantially matches). A punch hole 12a having a shape (for example, oval) is provided. A slide tool 13b for forming the through hole 5c is closely fitted in the punched hole 12a so as to be able to advance and retreat with respect to the side wall 14. The front end surface 20a of the slide tool 13b used in the present embodiment has one end (the upper end in FIGS. 2 to 5) in the width direction (vertical direction in FIGS. 2 to 5) of the punch hole 12a (or the through hole 5c). Part) is a flat surface 21 parallel to the inner surface of the mold element 15, and the intermediate part or the other end part (the lower end part in FIGS. 2 to 5) is separated from the side wall 14 as the distance from the flat surface 21 increases. The inclined surface 22 is inclined. During the hydroforming process for forming the bulging portion 7a in a part of the metal tube 3, the slide tool 13b is advanced in the punch hole 12a, and the flat surface 21 is connected to the inner surface of the mold element 15. Keep them on the same plane. Therefore, the portion corresponding to the inclined surface 22 in the tip surface 20 a of the slide tool 13 b is in a state of being recessed from the inner surface of the mold element 15.

  While the slide tool 13b is advanced as described above, the bulge is introduced while introducing a hydraulic pressure into the metal tube 3 and applying a force in the direction of compressing the metal tube 3 in the axial direction. Part 7a is formed. In this case, as described above, the plate thickness of the side wall 14 of the bulging portion 7a becomes smaller as it goes upward in FIGS. In the case of the present embodiment, as the bulging portion 7a is processed, a part of the side wall 14 of the bulging portion 7a that is opposed to the inclined surface 22 as shown in FIG. And slightly enters the gap 23 existing between the inclined surface 22 and the inclined surface 22. Then, a tensile stress in a direction perpendicular to the shearing surface is applied to the portion that has entered the gap 23 in this way, and a portion that strikes the blade edge portion 26 that exists at the peripheral edge portion of the punched hole 12a at a part of the side wall 14 Shear stress is applied.

That is, of the both end edge portions of the portion facing the gap 23, the side facing the continuous portion of the flat surface 21 and the inclined surface 22 (upper side in FIG. 2) is perpendicular to the slight shear surface. In addition to the stress in the pulling direction, bending stress is applied, and a part of the side wall 14 is bent. On the other hand, a shearing stress is applied to the side (lower side in FIG. 2) facing the cutting edge portion 26 existing at the opening peripheral edge of the punching hole 12a by the cutting edge portion 26 and the hydraulic pressure. Shearing is started at the part. At the same time, the thickness T _{4 of} this portion becomes smaller (T ₄ <T ₂ ) than the thickness T ₂ (see FIG. 24) in the state where the gap 23 does not exist.

On the other hand, the portion corresponding to the continuous portion of the flat surface 21 and the inner surface of the mold element 15 in the side wall 14 facing both end edges in the width direction of the punch hole 12a is still in the state shown in FIG. Since the shearing process has not been started, the thickness T ₃ of this part is also plastically deformed radially outward by a part of the metal tube 3 by the hydroforming method as shown in FIGS. Thus, it is not different from the state in which the bulging portion 7a is simply formed. That is, the plate thickness T ₃ of the above portion is not particularly reduced by using the slide tool 13b of this embodiment.

Thus, in the case of the present embodiment, the shape of the front end surface 20a of the slide tool 13b is devised, and the position of the front end surface 20a is appropriately regulated when performing the hydroforming process. Among the portions of the portion facing the punching hole 12a, the shearing process is started first from the side with the larger plate thickness (the lower side in FIG. 2). Further, the difference between the plate thicknesses T ₄ and T ₃ of the side wall 14 located at both edge portions in the width direction of the punch hole 12a can be kept small. That is, at the end of the hydroforming process, the thickness of the relatively large portion is reduced (from T ₂ ) to T _4, and the thickness of the relatively small portion is not reduced, but remains at T _3. The plate thicknesses T ₄ and T ₃ at both edges in the width direction can be made substantially equal (T ₄ ≈T ₃ ), and the end timing of the shearing process can be easily aligned (can be easily ended simultaneously).

  Therefore, as shown in FIG. 3, the slide tool 13b starts to retract in the punch hole 12a. By starting the retreat, the shearing process is started even on the side where the plate thickness is small (upper side in FIG. 3) in the part of the side wall 14 facing the punch hole 12a. From this state, when the slide tool 13b is further retracted as shown in FIG. 4, the entire circumference of the part of the side wall 14 that faces the punch hole 12a (the side with the larger thickness and the side with the smaller thickness) In the meantime, the shearing process proceeds. As the shearing process proceeds, cracks as shown in FIG. 1C are generated almost simultaneously on the entire circumference of the part of the side wall 14 facing the punch hole 12a. To do.

As a result, as shown in FIG. 5, the portion facing the punched hole 12a is punched out by the hydraulic pressure existing in the inner portion of the side wall 14 to become a punched piece 10c, and is pushed into the punched hole 12a. . At this time, the peripheral portion of the portion facing the punched hole 12a is ruptured from the shearing process, and this rupture is caused by the fact that the shearing process is started first from the portion where the plate thickness is large as described above. The plate thicknesses T ₄ and T ₃ of the peripheral portion of the portion are almost equal over the entire circumference (T ₄ ≈T ₃ ), and the timing of the end of the shearing process of this portion can be easily aligned, so that the entire circumference of the peripheral portion is Accordingly, the punched pieces 10c are generated substantially at the same time. As shown in FIG. 25 described above, a part of the side wall 14 that faces the punched hole 12a does not remain connected to the side wall 14. As a result, the through hole 5c can be reliably formed in a portion of the side wall 14 that is aligned with the punch hole 12a.

  Further, the punched piece 10c is not pushed into the punched hole 12a and remains in the metal tube 3 including the bulging portion 7a. Therefore, the process and apparatus for taking out the punched piece 10c from the inside of the metal tube 3 after forming the through hole 5c are unnecessary. For this reason, the cost required for manufacturing the product can be reduced, for example, the device for manufacturing the product including the bulging portion 7a and the through hole 5c can be reduced in size (space saving).

In order to surely punch out the portion to be the through-hole 5c, the shearing process is started earlier on the side where the plate thickness is larger than that on the same side, or the plate thicknesses at both edges in the width direction. The degree of making T ₄ and T ₃ substantially equal and making it easy to align the timing of the end of the shearing process is determined experimentally and experimentally according to the material of the metal tube 3 and the original plate thickness. For example, when a through hole is formed in a column bracket provided integrally with a steering column made of a mild steel plate, an aluminum alloy plate, etc., by appropriately devising the shape of the tip portion of the slide tool 13b, the shearing process can be started. Shift the timing. Further, as described above, in order to make the relationship between the plate thicknesses T ₄ and T _{3 at} the both end edges in the width direction easy to align the timing of the end of the shearing process, the width of the inclined surface 22 in the width direction is set. The dimensions are regulated based on experimental data in relation to the hydraulic pressure, the material of the metal tube 3 and the original plate thickness.

  The punched piece 10c pushed into the punched hole 12a forms, for example, a bulging portion 7a, and the metal tube 3 having a through hole 5c formed in a side wall 14 of the bulging portion 7a After taking out from the mold 6a constituted by the mold element 15, the slide tool 13b is advanced and pushed out from the punching hole 12a so that it can be easily taken out from the mold 6a. Alternatively, when the metal tube 3 is made of a magnetic material such as a mild steel plate, the metal tube 3 is taken out from the mold 6a, and then the punched piece 10c is adsorbed by a magnet and taken out from the hole 12a. You can also do things. Furthermore, a discharge passage having a size that allows the punched piece 10c to pass through the punched hole 12a to the external space can be provided inside the mold 6a. In this case, after the punched piece 10c pushed into the punched hole 12a by the hydraulic pressure introduced into the metal tube 3 is taken out of the mold 6a, the punched hole 12a is separately provided. The air is discharged from the hole 12a by air pressure or fluid pressure introduced into the inside. In any case, the punched piece 10c pushed into the punched hole 12a with the processing of the through hole 5c is discharged from the punched hole 12a prior to the next processing operation.

  In the case of the present embodiment, the flat surface 21 of the tip surface 20a of the slide tool 13b is present at the same position as the inner surface of the mold element 15 in the initial stage of the through hole forming process shown in FIG. Yes. However, as shown in FIG. 6, the flat surface 21 may be present at a position slightly recessed from the inner surface. In this case, as shown in FIG. 6, compared with the state in which the flat surface 21 is not recessed from the inner surface of the mold element 15, the portion having a small plate thickness is slightly pushed into the punched hole 12a. Therefore, the deviation of the start timing of the shearing process is reduced between the portion where the plate thickness is large and the portion where the plate thickness is small. Which of FIG. 2 and FIG. 6 is used is determined by design in accordance with the difference between the portion with a large plate thickness and the portion with a small plate thickness (conditions are set by experiment etc.).

7 to 8 show a second embodiment of the present invention corresponding to claims 1, 4, and 6-9 . The tip surface 20b of the slide tool 13c used in the present embodiment is also the same as the flat surface 21a facing the portion of the side wall 14 where the plate thickness is relatively small, as in the first embodiment. And an inclined surface 22a facing a portion having a relatively large plate thickness. However, in the case of the slide tool 13c used in the present embodiment, the inclination angle of the inclined surface 22a is made gentler than that of the inclined surface 22 (see FIGS. 2 to 6) of the slide tool 13b used in the first embodiment. ing.

  In the case of the present embodiment, the pressure of the slide tool 13c is slightly protruded from the inner surface of the mold element 15, and a hydraulic pressure is introduced into the inside of the metal tube 3. Hydroforming is performed to plastically deform a part of the bulge 7 radially outward to form the bulging portion 7a. That is, the flat surface 21a, which is the most protruding portion of the tip surface 20b of the slide tool 13c, is protruded from the inner surface of the mold element 15. On the other hand, a portion of the inclined surface 22a that is the least protruding portion of the tip surface 20b is a portion that is farthest from the flat surface 21a, and is a portion that matches the inner surface of the mold element 15. Position. In this state, a hydraulic pressure is introduced into the inside of the metal tube 3, and a part of the metal tube 3 is bulged outward in the radial direction to form the bulging portion 7a.

  Since the tip of the slide tool 13c protrudes from a part of the inner surface of the mold element 15, one side wall 14 constituting the bulging portion 7a is formed in the state where the bulging portion 7a is formed. As shown in FIG. 7, the portion bends following the tip of the slide tool 13c. That is, the portion of the side wall 14 that is in contact with the flat surface 21a is farthest from the inner surface of the mold element 15, and the portion that is in contact with the inclined surface 22a is along the inclined surface 22a. Inclined in such a way that the distance from the inner surface of the mold element 15 increases toward the flat surface 21a.

  Therefore, from this state, as shown in FIG. 8, if the slide tool 13 c is displaced in the direction of retracting from the side wall 14 inside the punch hole 12 a, a part of the side wall 14 is aligned with the punch hole 12 a. The portion to be cut is torn around the entire circumference of the hole 12a, and a through hole 5c corresponding to the hole 12a is formed.

In the case of the present embodiment, a portion of the side wall 14 that is aligned with the punched hole 12a is broken over the entire circumference of the punched hole 12a for the following reason. First, in order to form the bulging portion 7a, a part of the side wall 14 of the bulging portion 7a is formed at the final stage of the step of forming the bulging portion 7a by applying hydraulic pressure to the inside of the metal tube 3. Is pressed against the tip of the slide tool 13c, and the portion is deformed following the tip. Specifically, among the portions of the side wall 14 corresponding to both end edges of the portion where the through hole 5c is to be formed, the portion on the side where the plate thickness is reduced (the upper side in FIG. 7) is the slide. When the tool 13c is retracted to form the through hole 5c, the tool 13c is deformed (bent) relatively largely in the direction opposite to the direction of deformation. In this state, the thickness of the bent portion is T ₆ . On the other hand, the portion having the relatively large thickness (the lower side in FIG. 7) is deformed in the direction opposite to the direction of deformation when the through hole 5c is formed, but the amount of deformation is small. Ri, the thickness of the part, the T _5.

Therefore, from the state in which the portion where the through hole 5c is to be formed in a part of the side wall 14 is deformed as described above, the slide tool 13c is placed in the punch hole 12a, and FIG. When retracted a little to the extent shown, shearing is started immediately as shown in FIG. 2 in the relatively large plate thickness T ₅ , whereas the relatively small plate thickness T ₆ In the part, shearing has not yet started. Rather, this relatively small plate thickness T ₆ portion is compressed in the direction perpendicular to the shear plane, and a compressive stress is applied to make it difficult for cracks to occur. Further the slide tool 13c from the state in the vent hole 12a, when the slightly retracted to the extent shown in FIG. 3 showing the first embodiment described above, the shearing at the portion of the relatively small thickness T ₆ Be started. When the slide tool 13c is further retracted through the state of FIG. 4 showing the first embodiment, a part of the side wall 14 facing the punch hole 12a as shown in FIG. The shearing process proceeds on the entire circumference (the portion having the relatively large plate thickness T _{5 and} the portion having the relatively small plate thickness T _{6 and} the portion in between). With the progress of the shearing process, cracks as shown in FIG. 1C described above occur almost simultaneously on the entire circumference of the part of the side wall 14 facing the punch hole 12a. .

As a result, as shown in FIG. 8, the portion facing the punched hole 12a is punched out by the hydraulic pressure existing in the inner portion of the side wall 14 to form a punched piece 10c and is pushed into the punched hole 12a. . In addition, as described above, cracks are generated almost simultaneously in the entire circumference of the part of the side wall 14 facing the punch hole 12a in addition to shifting the timing of starting the shearing process. It is also considered that the reduction in the difference in the plate thickness of each part contributes. That is, as shown in FIG. 7, when the slide tool 13c is retracted from the side wall 14 in the hole 12a, a portion of the side wall 14 that matches the hole 12a is located in the hole 12a. Is pushed into. At this time, the portion having the relatively large plate thickness T ₅ immediately starts to be pushed into the hole 12a. On the other hand, the portion with the small plate thickness T ₆ is once deformed until it becomes parallel with the other portion, and then pushed into the hole 12a. Then, the portion where the thickness T ₆ is small is once deformed until it becomes parallel to the other portion, and further, in the process of being pushed into the punched hole 12a, a compressive stress is applied to this portion, and at the same time, the thickness of this portion Slightly increases (greater than T ₆ ). As a result, a portion of the side wall 14 that faces the punch hole 12a is pushed into the punch hole 12a while breaking along the entire periphery of the peripheral edge of the punch hole 12a. It is formed.

  In the case of the present embodiment, at the stage of forming the bulging portion 7a as shown in FIG. 7, among the inclined surfaces 22a of the tip surface 20b of the slide tool 13c, the end portion on the side far from the flat surface 21a is It may be positioned in a portion slightly recessed from the inner surface of the mold element 15. In this case, as shown in the figure, the portion of the side wall 14 of the bulging portion 7a that is in contact with the portion is slightly punched through the hole 12a as compared with the state in which the portion is not recessed from the inner surface of the mold element 15. Since it is pushed in, the shearing process starts at this part earlier, and the plate thickness at this part tends to be slightly thinner.

In any case, as shown in FIG. 7, a part of the metal tube 3 is bulged to form a bulging part 7a, and the tip surface of the slide tool 13c is formed on a part of the side wall 14 of the bulging part 7a. The difference between the plate thicknesses T ₅ and T ₆ of the side wall portion 14 corresponding to both end edges in the width direction of the side wall portion 14 is preferably viewed from the side where the plate thickness is large. If it is within 30%, more preferably within 20%, it is particularly difficult to cause a problem in forming the through hole 5c. That is, the manufacturing method of this embodiment is appropriate when the difference in plate thickness is larger than that in the case of Embodiment 1 described above. Further, the end portion of the inclined surface 22a which is the most concave among the tip surfaces 20b and which is far from the flat surface 21a may coincide with the inner surface of the mold element 15 as shown in FIG. , be positioned a little recessed portion than the inner surface as described above, further, it may be slightly protrude from the inner surface.

FIG. 9 shows, as Example 3 of the present invention, slide tools 13b and 13c used in Example 1 and Example 2 described above, and two examples of slide tools that can be replaced with the slide tools 13b and 13c. A total of three slide tools are shown. That is, the shape of the tip of the slide tool used when forming the through hole 5c as in the above two embodiments is the inclined surface 22 having a linear cross-sectional shape as shown in FIG. In addition to the slide tool 13b (13c) provided with 22a, as shown in FIGS. 9B and 9C, it is provided with curved inclined portions 24 and 24a having a circular cross-sectional shape. Although not shown, the cross-sectional shape of the inclined surface may be a composite surface in which a straight line and a curve are combined. As shown by the broken line in FIG. 9A, the inclination angle θ of the inclined surface 22 (22a) formed on the tip surface 20a (20b) of the slide tool 13b (13c) is set to the tip surface 20a (20b). ) In the middle of the length direction (front and back direction in FIG. 9). Such consideration is necessary when the thickness of the portion where the through hole is to be formed by hydropiercing changes not only in the width direction but also in the length direction of the through hole. In this case, it instead to the inclination angle θ of the inclined surface 22 (22a), or by changing the width W ₂ of the flat surface 21 (21a), also to vary both. Thus, depending on the form of the thickness distribution of the material, the shape of the tip surface 20a (20b) is changed three-dimensionally as necessary.

9A shows the slide tool 13b (13c) used in the first embodiment and the second embodiment. The dimensions of such a slide tool 13b (13c) are as follows, for example. It regulates like That is, the width of the slide tool 13b (13c) is W ₁ , the width of the flat surface 21 (21a) of the tip surface 20a (20b) of the slide tool 13b (13c) is W ₂ , and the inclined surface 22 (22a) ) Tilt angle is θ,
0 ≦ W ₂ ≦ 0.9W ₁
0.3 ° ≦ θ <90 °
The range of can be adopted.
Preferably,
0.01W ₁ ≦ W ₂ ≦ 0.9W ₁
0.3 ° ≦ θ <90 °
More preferably,
0.2W ₁ ≦ W ₂ ≦ 0.8W ₁
1 ° ≦ θ ≦ 20 °
Particularly preferably,
0.2W ₁ ≦ W ₂ ≦ 0.7W ₁
3 ° ≦ θ ≦ 20 °
Set within the range.

In short, the width W ₁ of the slide tool 13b (13c) is determined according to the width of the through-hole 5c to be formed, but the remaining width W ₂ and the inclination angle θ are related to the material and thickness of the metal tube 3. The optimum value is selected by experiment. If the width W ₂ is too large flat surface 21 (21a), made this by that projecting the flat face 21 (21a), difficult to obtain the timing of the shearing start, the effect of adjusting the timing of cracking to fracture enough . On the contrary, if the width W ₂ is too small, it is difficult to ensure the mechanical strength of the flat surface 21. Therefore, if there is no problem in securing the mechanical strength of the slide tool, the flat surface 21 may be omitted. If the inclination angle θ is too small, it is difficult to obtain the adjustment effect of each timing by retracting the slide tool 13b (13c). On the contrary, when the inclination angle θ is too large, it is difficult not only to secure the mechanical strength of the flat surface 21 (21a), but also the thick wall side is easily sheared, and the adjustment of each timing described above. It becomes difficult.

9B and 9C show a partially cylindrical concave curved surface {in the case of FIG. 9B} having a radius of curvature of the cross-sectional shape R or a convex curved surface {(C of FIG. )}, The inclined portions 24 and 24a are formed in place of the inclined surfaces 22 (22a). However, the slide tools 13d and 13e having such inclined portions 24 and 24a are also formed in each portion. Select dimensions within the following range.
That is, each of these slide tool 13d, W ₁ width of 13e, each of these slide tool 13d, 13e of the front end surface 20c, the flat surface 21b of the 20d, and the width of 21c and W _2,
0 ≦ W ₂ ≦ 0.9W ₁
Preferably,
0.01W ₁ ≦ W ₂ ≦ 0.9W ₁
It can be set within the range. The value of the radius of curvature R of the cross-sectional shape of the inclined portions 24, 24a can be arbitrarily set. For each value, the optimum value is selected by experiment according to the material and thickness of the metal tube 3 as in the case of the slide tool 13b (13c) shown in FIG. is there.
In short, in carrying out the present invention, when the slide tool is retracted inside the punched hole, even if there is a difference in the plate thickness, such as the side wall of the bulging portion, the thickness of the plate is reduced on both sides of the punched hole. Any slide tool having a tip shape that can be simultaneously broken along the entire circumference, such as reducing the difference, can be used in the practice of the present invention.

Further, the protruding amount S (FIG. 7) or the recessed amount −S (FIG. 6) from the inner surface of the mold element 15 of the tip surfaces 20a, 20b of the slide tools 13b, 13c forms a through hole in the side wall 14. as the thickness of the portion to be T (corresponding to T ₃ in FIG. 2) reference, | T |> | is preferably regulated to within the range of | S. If this protrusion amount S is too large, the compressive stress applied to the portion having a small thickness as the slide tool moves backward becomes excessive, and cracks do not occur even if the shearing process proceeds. As a result, a situation occurs in which only the thick portion is sheared, making it difficult to implement the present invention. Also, if the amount of depression -S is excessive, the material excessively enters the punched hole from the initial state, and the respective timings are set according to the thick side and the small side depending on the shape of the tip surface of the slide tool. The effect of adjustment is reduced. In other words, it is difficult to adjust these timings.
Note that when forming the through-hole, with respect to the hydraulic pressure P that acts on one side of the side wall 14 (the side opposite to the mold element 15) while retracting the slide tool, the shear resistance of the metal material is r, When the thickness is T, the perimeter of the through hole is L, and the area of the through hole is S, regulation is performed so that P> (r · T · L) / S is satisfied.

FIG. 10 shows a fourth embodiment of the present invention corresponding to claims 2 and 7 to 9 . In the case of this embodiment, unlike the case of each embodiment described above, the mold 6 side is devised. That is, the curvature radii of the cross-sectional shapes of the blade edge portions 26a and 26b existing at the both edges in the width direction of the opening peripheral portion of the punch hole 12b formed in the mold element 15 facing the side wall 14 where the through hole is to be formed are mutually equal. It is different. Specifically, the radius of curvature of the cross-sectional shape of the lower blade edge portion 26a in FIG. 10 where the thicker side of the side wall 14 is to be sheared is made smaller (sharp edge). On the other hand, the curvature radius of the cross-sectional shape of the upper blade edge portion 26b in FIG. The front end surface 20 of the slide tool 13 inserted into the punched hole 12b is flat over the entire surface.

  In the case of the present embodiment, by making the radius of curvature of the cross-sectional shape of the cutting edge portion 26b to be sheared on the side where the plate thickness is small, the shearing is difficult to proceed on the side where the plate thickness is small. The generation timing of the crack leading to the break on this side is delayed as compared with the case where the blade edge portion 26b has a sharp edge. In short, in the case of the present embodiment, since the plate thickness is originally small, the timing of occurrence of cracks leading to breakage tends to be delayed, and this timing tends to be delayed.

For this reason, in the case of this embodiment, even when the shearing start timing is the same on the side where the plate thickness is small and the side where the plate thickness is large, the generation timing of cracks leading to breakage (timing of the end of the shearing phenomenon) is almost the same. Therefore, it is possible to perform complete outer-piercing hydropiercing with no difference in thickness.
In addition, the shape of the front end surface 20 of the slide tool 13 is changed as in the first to third embodiments, in combination with the change in the radius of curvature of the cross-sectional shape of each of the blade edge portions 26a and 26b as in the present embodiment. It is also possible to devise (the invention described in claim 3) . Specifically, the radius of curvature of the cross-sectional shape of the cutting edge portion is increased on the side of the plate thickness where it is necessary to reduce the sensitivity to shear, and the tip surface 20 of the slide tool 13 protrudes into the mold element 15. To delay the start of shearing. On the other hand, the radius of curvature of the cross-sectional shape of the cutting edge portion is reduced on the thicker side, and the tip surface 20 of the slide tool 13 is recessed outward of the mold element 15 to promote shearing.

  11 to 12 show a fifth embodiment of the present invention. In the case of the present embodiment, when the deformed through hole 5d is formed in the side wall 14 of the bulging portion 7a formed by plastic deformation of a part of the metal tube 3 radially outward by the hydroforming method. It shows. The through-hole 5d is formed by superposing (combining) an oval portion having a relatively small width dimension as shown in FIG. 12A and an oval portion having a relatively large width dimension as shown in FIG. Thus, a keyhole shape as shown in FIG. However, this keyhole-shaped through hole 5d is processed at once by a slide tool having a cross-sectional shape of a keyhole. The shape of the tip surface of the slide tool is formed in accordance with any of the embodiments described above. Even if such a keyhole-shaped through-hole 5d is used, it can be processed when the plate thickness is uniform. If the present invention is applied, even if the plate thickness is non-uniform, it can be made of metal. Regardless of whether the member is annular or plate-like, it can be reliably processed by hydropiercing. In addition, as for the shape of the portion where the through hole 5d is to be formed in a part of the metal member, any shape such as a flat surface, a partial arc surface, and a curved surface may be used (the tip surface shape of the slide tool is adjusted to that).

FIG. 13 shows a sixth embodiment of the present invention corresponding to the tenth aspect . In the case of the present embodiment, a through-hole having a large aspect ratio (slit-like) is formed in the side wall 14 of the bulging portion 7a formed by plastic deformation of a part of the metal tube 3 radially outward by the hydroforming method. 5e is shown when formed in a state straddling the inclined portion 29 of the bulging portion 7a. In the case of the present embodiment, the tip surface shape of the slide tool is matched with any of the embodiments described above, and is also formed according to the outer surface shape of the side wall 14 where the through hole 5e is to be formed. Even in the case of the slit-shaped through-hole 5e that exists in such a state as to straddle the inclined portion 29, it can be reliably processed by hydropiercing by applying the present invention, similarly to the above-described fifth embodiment.

FIG. 14 shows a seventh embodiment of the present invention corresponding to the tenth aspect . In the case of the present embodiment, a keyhole-shaped through hole 5f is formed on the side wall 14 of the bulging portion 7a formed by plastic deformation of a part of the metal tube 3 radially outward by the hydroforming method. The case where it forms in the state straddling the inclination part 29 of the protrusion part 7a is shown. Also in this embodiment, the tip surface shape of the slide tool is formed in accordance with any of the embodiments described above, and in accordance with the outer surface shape of the side wall 14 in which the through hole 5f is to be formed. Even in the case of the keyhole-shaped through-hole 5f that exists in such a state that straddles the inclined portion 29, by applying the present invention, as in the fifth and sixth embodiments described above, it is reliably processed by hydropiercing. it can.

  An experiment conducted to confirm the effectiveness of the present invention will be described. Hydroforming and hydropiercing were actually performed by the method of Example 2 shown in FIGS. That is, assuming the manufacture of an outer tube for a steering column with an integrated column bracket, a bulging portion is formed in the axial middle portion of the metal tube by hydroforming, and then by hydropiercing in the same mold. Oval holes were formed in the side wall portions on both sides of the bulging portion (see FIGS. 15 to 17). As the slide tool combined with the mold, a tool having the shape shown in FIG. 9A in which the front end surface is formed of a flat surface and an inclined surface was used.

  The metal pipe used for the experiment is a carbon steel pipe for machine structure (STKM11A), which has an outer diameter of 60.5 mm, a wall thickness of 2.0 mm, and a total length of 500 mm. The mechanical test value of this material is that the yield point is 300 MPa, the tensile strength is 400 MPa, and the elongation is 40%. The length of the oval hole for forming the through hole was 60 mm in the major axis direction and 10 mm in the minor axis direction.

The tube expansion rate at the bulging portion formed by hydroforming was about 30%, and the plate thickness was 1.8 mm on the small side and 2.0 mm on the large side. Relationship between the width W ₁ of the tip surface of the slide tool and the width W ₂ of the flat surface (land width ratio W ₂ / W ₁ ) in order to form oblong through holes in the side wall portions on both sides of the bulging portion by hydropiercing The inclination angle θ of the inclined surface with respect to the flat surface and the protrusion amount S of the flat surface at the initial position were variously changed. These values are shown in the following Table 1 together with the experimental results. The comparative example in Table 1 is a case where a slide tool having a flat tip surface is used.

  As clearly shown in Table 1, the peripheral edge of the through hole to be formed can be formed by appropriately selecting the shape of the tip surface of the slide tool and adjusting the timing of starting the shearing process and the timing of occurrence of cracks leading to fracture. The shearing phenomenon can be terminated at the same time in the entire part and can be broken all around. For this reason, complete hydropiercing without any uncut portion is possible even on both side walls of the bulging portion having a difference in plate thickness. Further, the metal tube processed product in which the through holes are formed in the both side walls of the bulging portion by the method of the present invention can be used as an outer tube for a steering column. Furthermore, the obtained outer tube has an integrated column bracket without a welded portion, and the drilling quality existing on both side walls of the bulging portion is high, so that the quality is extremely high. . In addition, since a series of operations within the same mold can efficiently perform from the formation of the bulging portion to the drilling process, the economic efficiency is very high.

When carrying out the present invention, the number of through holes formed in the metal member is not limited. In other words, when the number of through holes is one or two, even if the number is three or more, the present invention can be implemented by providing the mold with the necessary number of holes and slide tools. Is possible.
In addition, the shape of the through hole to be formed is not only a simple circle but also an oval, an ellipse, a substantially square, or a combination of these or a more complicated shape. It can be applied to the formation of For example, the structures of Examples 1 to 7 described above can be combined as appropriate. In this case, for example, it is conceivable that a plurality of through holes having different shapes are simultaneously formed by hydropiercing using a mold having a plurality of punch holes and a slide tool.
Furthermore, when the present invention is applied to form a through hole in a bulging portion formed by plastic deformation of a metal tube radially outward, it is not limited to the case where the metal tube is bulged in one direction. The present invention can be applied even when it is swollen over the entire circumference. That is, even when the metal tube is swollen over the entire circumference, there is a non-uniform thickness portion with a difference in plate thickness due to a partial change in the degree of swelling, etc. If it is necessary to form a through hole in the portion, the present invention can be applied.
In short, the present invention is not limited to the case where the through hole is formed in the bulging portion of the hollow member, but is used when the through hole is formed in a non-uniform thickness portion having a difference in plate thickness among various metal members. Is possible.

  In particular, when the present invention is applied, for example, to the manufacture of a column bracket integrated steering column, it is possible to obtain more excellent functions and effects than the basic functions and effects of the present invention described above. That is, when manufacturing such a steering column, as described in FIGS. 20 to 23, the hydroforming process for forming the bulging portion serving as the column bracket and the hole processing for forming the through hole are performed. The steps can be carried out continuously (substantially simultaneously). For this reason, it is possible to reduce the manufacturing cost by reducing the time and labor required for manufacturing the steering column as described above. Further, even when a plurality of through holes are formed in one member, it is not necessary to consider the positioning of this member and each through hole in order to position each through hole. A product in which a plurality of through-holes are accurately positioned can be obtained while suppressing the rise.

  In addition, when applying this invention to forming a through-hole in the bulging part of a column bracket, when applying to any part, including the peripheral part of the formed through-hole, the peripheral part of this through-hole In this case, a good surface with almost no deformation of the material such as anyone remains. For this reason, after this through hole is formed, post-processing for improving the accuracy of the surrounding portion is unnecessary or easy, and equipment and mechanisms for post-processing are unnecessary or simplified, thereby reducing equipment costs. Cost reduction by etc. can be aimed at.

In addition, each of the examples shown in the drawings shows a case where a non-uniform thickness portion having a difference in thickness is drilled (hydropiercing). However, even if the thickness (plate thickness) is the same, there is a difference in the degree of work hardening, and even when drilling (hydropiercing) is performed on a work hardening non-uniform part, the same problem as the above non-uniform thickness part occurs. It can happen. For this reason, in order to end the shearing phenomenon simultaneously in such a work hardening non-uniform portion, the shear start timing in this portion is adjusted according to the degree of work hardening (conditions are set in terms of design). You can also do things. In this case, for example, a portion where the degree of work hardening is remarkable is made to correspond to a portion having a large thickness (thickness) in the description of each of the above-described embodiments, and the degree of work hardening is low (or not work hardened). ) Part corresponds to a part having the same small thickness. The degree to which the timing of starting shearing is shifted depending on the degree of work hardening is obtained by experiment as in the case where the thickness is not uniform. Furthermore, it goes without saying that the present invention can be implemented with respect to portions where the thickness is not uniform and the degree of work hardening is different. Also in this case, the degree to which the timing is shifted is regulated by the experiment according to the thickness and the degree of work hardening.

The fragmentary sectional view which shows the advancing state of hydropiercing for demonstrating the principle of this invention. The expanded sectional view equivalent to the A section of Drawing 23 which shows Example 1 of the present invention in the state before forming a penetration hole. The figure similar to FIG. 2 which similarly shows the middle state of through-hole formation. The same figure as FIG. 2 which shows the state which continues. The figure similar to FIG. 2 shown in the state which formed the through-hole similarly. The figure similar to FIG. 2 which shows the modification of Example 1 of this invention. The expanded sectional view equivalent to the A section of Drawing 23 showing Example 2 of the present invention in the state before forming a penetration hole. The figure similar to FIG. 7 shown in the state which formed the through-hole similarly. Sectional drawing which shows three examples of the slide tool for forming a through-hole as Example 3 of this invention. The expanded sectional view equivalent to the A section of Drawing 23 showing Example 4 of the present invention. 5A and 5B show a fifth embodiment of the present invention, in which FIG. 5A is a side view, and FIG. 5B and FIG. 5C are cross-sectional views showing portions where through holes are formed, cut in different directions. The partial side view for demonstrating the shape of a through-hole. The figure similar to FIG. 11 which shows Example 6 of this invention. The figure similar to FIG. 11 which shows Example 7 of this invention. Sectional drawing which shows the prior art example of the steering column which provided the column bracket integrally. Similarly a partial perspective view. B arrow view of FIG. (A) is the side wall part of a column bracket, (B) is CC sectional drawing of FIG. 17 which shows the state which expanded the side wall part further, respectively. Sectional drawing which shows three examples of the method of forming a through-hole in the bulging part formed by plastically deforming a metal tube. Sectional drawing which shows the preparatory process of the method of forming the bulging part in the metal pipe | tube considered previously, and also forming a through-hole in this bulging part. DD sectional drawing of FIG. Sectional drawing which shows the state which formed the bulging part in the metal pipe similarly. EE sectional drawing of FIG. The A section expanded sectional view of FIG. FIG. 25 is a cross-sectional view similar to FIG. 24 for explaining the reason why a through hole is not formed by the previously considered method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering column 2 Column bracket 3 Metal tube 4 Tilt bolt 5, 5a, 5b, 5c, 5d, 5e, 5f Through-hole 6, 6a Die 7, 7a Protruding part 8, 8a Cylinder hole 9, 9a Punch 10, 10a 10b, 10c Punched piece 11 Hollow member 12, 12a, 12b Punched hole 13, 13a, 13b, 13c, 13d, 13e Slide tool 14 Side wall 15 Mold element 16 Circular hole portion 17 Recessed portion 18 Center hole 19, 19a, 19b Shaft Push tool 20, 20a, 20b, 20c, 20d Tip end surface 21, 21a, 21b, 21c Flat surface 22, 22a Inclined surface 23 Gap 24, 24a Inclined portion 25 Metal plate 26, 26a, 26b Cutting edge portion 27 Shear surface 28 Crack 29 Slope

Claims (10)

A part of a member made of metal and having at least a part in a plate shape has a through-hole in a non-uniform thickness portion having a difference in thickness of the plate-shaped portion. In order to provide it in a penetrating state, one side of this non-uniform thickness portion is in contact with the mold, while applying hydraulic pressure to the other surface of this non-uniform thickness portion, The part corresponding to the punched hole provided in the mold at the part is pushed into the punched hole. When hydropiercing is performed, as a slide tool inserted into the punched hole of the mold, a material to be subjected to shearing is used. Formed by using a slide tool that has a shape in which the tip surface protrudes inward of the mold on the small thickness side and is recessed in the outward direction of the mold on the large thickness side according to the wall thickness distribution It has a through-hole, characterized by simultaneously terminating the shearing phenomenon on the entire periphery of the above-mentioned through-hole Method for producing a metal-made member. A part of a member made of metal and having at least a part in a plate shape has a through-hole in a non-uniform thickness portion having a difference in thickness of the plate-shaped portion. In order to provide it in a penetrating state, one side of this non-uniform thickness portion is in contact with the mold, while applying hydraulic pressure to the other surface of this non-uniform thickness portion, When the part corresponding to the punched hole provided in the mold is pushed into the punched hole at the part, and the hydropiercing is performed, the radius of curvature of the cross-sectional shape of the blade edge part which is the peripheral part of the punched hole is obtained as the mold. According to the thickness distribution of the material to which the cutting edge is subjected to the shearing process, the above-mentioned should be formed by using a mold formed small on the thick side and large on the small thickness side. characterized in that to terminate the shearing phenomena simultaneously throughout the periphery of the through hole, a metal member having a through hole Manufacturing method. As a mold, the radius of curvature of the cross-sectional shape of the cutting edge part, which is the peripheral part of the punched hole, is small on the thick side according to the wall thickness distribution of the material on which the cutting edge part is subjected to shearing processing. The manufacturing method of the metal member which has a through-hole of Claim 1 using the metal mold | die formed largely on the small side of this . On the inside of the punch hole provided in the mold and having a shape and size suitable for the through hole, the portion of the non-uniform thickness portion where the plate thickness is small is the same as the thick portion. Insert a slide tool having a tip surface protruding toward the surface, and apply hydraulic pressure to the other surface of the uneven thickness portion with the inner surface of the mold abutting against one surface of the uneven thickness portion. In addition, the slide tool is displaced in a direction to retract from the uneven thickness portion, and a portion of the uneven thickness portion corresponding to the punch hole is pushed into the punch hole by the hydraulic pressure. The manufacturing method of the metal member which has a through-hole in any one of Claims 1-3 . By positioning the most protruding part of the tip surface of the slide tool at the part that matches the inner surface of the mold, this tip surface is placed on one side of the uneven thickness part, and the thickness of the uneven thickness part is the plate thickness. The through tool is formed by displacing the slide tool in the direction of retracting from the non-uniform thickness portion inside the punched hole from the state where it is abutted on the small side and facing the gap on the large side. The manufacturing method of the metal member which has a through-hole described in any one of Claim 1, Claim 3, and Claim 4 which referred to Claim 1 or Claim 3 . The most projecting portion of the tip surface of the slide tool is projected from the inner surface of the mold, and the least projecting portion is positioned at a portion that coincides with or is recessed from the inner surface, and the tip surface is slid. By moving the slide tool in the direction of retreating from the non-uniform thickness portion inside the punch hole from the state where it is in contact with one surface of the non-uniform thickness portion bent along the tip of the tool The manufacturing method of the metal member which has a through-hole as described in any one of Claim 1, Claim 3, and Claim 4 which quoted Claim 1 or Claim 3 which forms. Some at the portion where the plate thickness is gradually changed in the thickness uneven part, a side wall of the bulge portion formed by inflating a part of the material by hydroforming method, any one of claims 1 to 6 A method for producing a metal member having a through-hole described in item 1. A metal member is a steering column in which a part of a hollow tube is expanded radially outward by a hydroforming method, and a through hole is formed in a side wall portion of the expanded portion formed by the expansion. Processing of the expanded portion The method for producing a metal member having a through hole according to claim 7 , wherein the through hole is formed following the work. When considering a virtual plane that includes the central axis of the hollow tube and expands in a direction perpendicular to the direction in which the bulging portion bulges, the position where the entire through hole deviates from the virtual plane in the bulging direction. The manufacturing method of the metal member which has the through-hole described in Claim 8 formed in this. And inflatable portion and inflatable are not part is continuous through an inclined portion or the stepped portion, at least a portion of the through hole, is formed in the inclined portion or the stepped portion of claim 8-9 The manufacturing method of the metal member which has a through-hole described in any one of them.

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