Processing method by hydroforming, mold, mold module, and hydroforming processing apparatus.

Abstract

To control a thickness of a workpiece with higher accuracy.SOLUTION: A processing method by hydroforming includes: an aligning step of aligning a tubular workpiece on a die formed according to a first direction corresponding to an extension direction of the workpiece; a lubricant supply step of supplying a lubricant in a center area of a flat surface part interposed by corner parts of a cross section of a die of an inner side surface of the die in a width direction orthogonal to the first direction of the workpiece; a forming step of deforming the workpiece along the inner side surface of the die by supplying a liquid from a supply source different from a supply source of the lubricant to the inner side of the workpiece while supplying the lubricant, and applying a pressure from an inner side of the workpiece.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a processing method by hydroforming, a mold, a mold module, and a hydroforming processing apparatus.

Background Art

[0002] Hydroforming is a processing method in which internal pressure is applied to a steel pipe or the like to cause it to bulge and conform to the shape of a mold, thereby forming it into a desired shape. Since hydroforming can impart work hardening or perform integral molding, it is expected to contribute to weight reduction of vehicle bodies such as automobiles. On the other hand, in hydroforming, due to the friction between the mold and the steel pipe (workpiece), changes in wall thickness after processing may become a problem.

[0003] In response to such a problem, for example, Patent Document 1 discloses a technique for controlling the friction between a mold and a workpiece by providing a large number of holes on the inner surface of the mold and supplying a lubricating fluid through such holes.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the technique disclosed in Patent Document 1, since the lubricating fluid also flows to portions where there is no contact or weak contact between the workpiece and the mold, sufficient contact pressure due to the lubricating fluid cannot be obtained, it is difficult to obtain the effect of fluid lubrication, and it is difficult to control the wall thickness of the workpiece.

[0006] Therefore, the present disclosure has been made in view of the above problems, and an object thereof is to provide a processing method by hydroforming, a mold, a mold module, and a hydroforming processing apparatus capable of more accurately controlling the wall thickness of a workpiece.

Means for Solving the Problems

[0007] According to the present disclosure, there is provided a processing method by hydroforming, including: an arranging step of arranging a tubular workpiece in a mold formed according to a first direction corresponding to the elongation direction of the workpiece; a lubricant supply step of supplying a lubricant to a central region of a flat portion sandwiched between corner portions of a cross section of the mold in a width direction orthogonal to the first direction of the workpiece on an inner surface of the mold; and a forming step of applying pressure from inside the workpiece by supplying a liquid from a supply source different from the lubricant while supplying the lubricant, and deforming the workpiece along the inner surface of the mold.

[0008] Further, according to the present disclosure, there is provided a mold for forming a tubular workpiece, the mold having at least one wall portion extending in a longitudinal direction, and a supply port for supplying a lubricant being provided in a central region of a flat portion sandwiched between corner portions of the mold in a width direction orthogonal to the longitudinal direction of the wall portion on an inner surface of the wall portion.

[0009] Further, according to the present disclosure, there is provided a mold module detachably provided on a flat portion sandwiched between corner portions in a cross section of a mold for forming a tubular workpiece, a supply port for supplying a lubricant being provided in a central region in a width direction of the mold module on an inner surface of the mold module.

[0010] Also, according to the present disclosure, there is provided a hydroforming processing apparatus including: a mold having at least one longitudinally extending wall portion, and a supply port for supplying a lubricating fluid provided in a central region in a width direction orthogonal to the longitudinal direction of the wall portion on an inner surface of the wall portion; a lubricating fluid supply source for supplying the lubricating fluid at a position in a central region of a flat surface portion sandwiched between corner portions in a cross section of the mold in a width direction orthogonal to the longitudinal direction of the workpiece, from the supply port on the inner surface of the mold; and an internal pressure fluid supply source for applying pressure from the inside of the workpiece by supplying a fluid from a supply source different from the lubricating fluid while supplying the lubricating fluid to deform the workpiece from the inside.

Advantages of the Invention

[0011] According to the present disclosure, the thickness of the workpiece can be controlled with higher accuracy.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Mode for Carrying Out the Invention

[0013] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

[0014] <Summary> First, an overview of the processing method by hydroforming according to an embodiment of the present disclosure will be described. FIGS. 1 and 2 are diagrams for explaining the overview of the processing method by hydroforming according to this embodiment. FIGS. 1 and 2 show a cross-sectional view orthogonal to the longitudinal direction (elongation direction) of the mold 1 and the workpiece (steel pipe) 2.

[0015] The mold 1 is a mold used for hydroforming and is composed of, for example, an upper mold and a lower mold. The mold 1 has at least one longitudinally extending wall portion. The workpiece 2 is placed between the upper mold and the lower mold, and a liquid such as high-pressure water is supplied into the interior of the workpiece 2 from the longitudinal end of the mold 1. As a result, the workpiece 2 bulges out and is pushed against the inner surface of the mold 1. Although the workpiece 2 according to this embodiment assumes a steel pipe, the workpiece 2 is not limited to such an example. For example, the workpiece 2 may be made of a different material such as other metals, or the workpiece 2 may be formed by joining a part of two plate-like members in addition to being tubular or cylindrical, and by bulging each plate-like member to form an annular member. These members are also defined as "tubular workpieces" in this embodiment.

[0016] In this embodiment, as shown in FIG. 1, while the workpiece 2 bulges by hydroforming, a lubricant is introduced from the outside to the inside of the mold 1. Such a lubricant may be any liquid such as water or oil, and the lubricant may contain additives such as molybdenum disulfide and graphite. As will be described in detail later, such a lubricant is supplied to the position of the central region in the width direction of the workpiece 2. The supply port of the lubricant is preferably provided at one location in the mold 1.

[0017] Then, as shown in FIG. 2, the workpiece 2 bulged by hydroforming follows the inner surface of the mold 1. At this time, a fluid lubricating layer is formed by the lubricating fluid between the mold 1 and the workpiece 2. At this time, since the lubricating fluid is supplied to the position of the central region of the workpiece 2, the lubricating fluid flows into the small gap between the mold 1 and the workpiece 2. Therefore, sufficient pressure is applied to the lubricating fluid, and the fluid lubricating layer can be formed along the mold 1. Note that the lubricating fluid can be discharged from, for example, another hole different from the supply port of the mold 1.

[0018] In this way, by providing the supply port of the lubricating fluid at the position with respect to the central region of the workpiece 2 in the mold 1, supplying the lubricating fluid to the mold 1 from the supply port during the processing by hydroforming, and applying sufficient pressure to the lubricating fluid to form the fluid lubricating layer, the friction between the mold 1 and the workpiece 2 is reduced, and the fluidity of the material of the workpiece 2 is improved. As a result, it becomes possible to more uniformly control the wall thickness of the workpiece 2 after processing by hydroforming. Hereinafter, a specific configuration example according to the present embodiment will be described.

[0019] <Configuration example> FIG. 3 is a diagram showing a configuration example of a processing apparatus by hydroforming according to the present embodiment. The processing apparatus according to the present embodiment includes a mold 1, a lubricating fluid pump 3 (lubricating fluid supply source), a Bourdon tube pressure gauge 4, a pressure sensor 5, an internal pressure fluid pump 6 (internal pressure fluid supply source), a Bourdon tube pressure gauge 7, and a pressure sensor 8. The mold 1 is composed of an upper mold 1A, a lower mold 1B, a lid mold 1C with a nozzle, and a lid mold 1D. Note that the processing apparatus according to the present embodiment is a type of apparatus that does not have a shaft-pushing punch mold that axially pushes the end of the so-called workpiece 2 along the longitudinal direction, but the present technology is not limited to such an example. That is, such a processing apparatus may have a shaft-pushing punch mold.

[0020] The workpiece 2 set inside the mold 1 bulges due to the pressure applied by the internal pressure liquid P1 supplied from the internal pressure liquid pump 6 through the lid mold 1C with a nozzle. At this time, the lubricating liquid L1 supplied from the lubricating liquid pump 3 through the supply port of the upper mold 1A forms a fluid lubricating layer between the surface of the workpiece 2 inside the mold 1.

[0021] Next, a configuration example of the mold 1 will be described. FIG. 4 is a perspective view showing a configuration example of the mold 1 according to the present embodiment. FIG. 5 is a cross-sectional view taken along a cross-section orthogonal to the longitudinal direction at the position where the inlet 1F and the supply port 11 in the longitudinal direction of the mold 1 according to the present embodiment are provided. FIG. 6 is a view showing an example of the internal structure of the upper mold 1A according to the present embodiment.

[0022] As shown in FIG. 4, the mold 1 is configured by combining an upper mold 1A and a lower mold 1B vertically. A space 1G for processing the workpiece 2 is provided between the upper mold 1A and the lower mold 1B, and the internal pressure liquid P1 is supplied from the nozzle of the lid mold 1C with a nozzle through the hole 1E. The supply port 11 is provided on the inner surface of the mold 1. Further, the supply port 11 is provided in the upper mold 1A. Such an inlet 1F is a hole for supplying the lubricating liquid L1 to the space 1G inside the mold 1. The inlet 1F is provided in the central region in the width direction W orthogonal to the longitudinal direction L (an example of the first direction) of the mold 1. The central region means the central region in the width direction of the flat portion 111 sandwiched between the corner portions 110 in the cross-sectional shape of the inner surface of the mold where the supply port 11 is provided in the longitudinal direction. Note that the inlet 1F and the supply port 11 may be provided in the lower mold 1B.

[0023] Note that the inlet 1F and the supply port 11 are connected by a single flow path, and it is preferable that the inlet 1F and the supply port 11 are provided in a one-to-one correspondence. Further, it is preferable that the lubricating fluid L1 flowing out from the inlet 1F through the supply port 11 is supplied only from one supply source (for example, the lubricating fluid pump 3). Thereby, the lubricating fluid L1 to which a high pressure is applied to the mold 1 can be introduced. When a plurality of supply ports 11 are provided, for example, each of the plurality of supply ports 11 is provided with a corresponding supply source of the lubricating fluid, or a valve is provided in the flow path connecting the plurality of supply ports 11 and the inlet 1F, and the valve may be controlled so that the lubricating fluid is supplied only to one supply port 11. Thereby, the pressure of the lubricating fluid can be maintained high. The positions where the plurality of supply ports 11 are provided are not particularly limited, but are preferably provided at positions close to each other.

[0024] Further, the mold 1 may be provided with a discharge port 12 for discharging the lubricating fluid L1 and a lead-out port 1H for allowing the lubricating fluid to flow out from the discharge port 12 to the outside of the mold 1. The number of such discharge ports 12 and lead-out ports 1H is not particularly limited.

[0025] Such a supply port 11 may be directly provided on the upper mold 1A, or may be provided on a mold module that is detachable from the upper mold 1A. Such a mold module may have a nested structure with respect to the mold 1. By using the mold module, it becomes possible to control the flow of the lubricating fluid between the mold and the steel pipe. Further, by making the mold module detachable from the mold, the shape of the mold surface can be easily changed. Note that the shape on the mold module described below may be set on the mold module or may be directly formed on the mold.

[0026] FIG. 7 is a diagram showing a first example of the mold module according to the present embodiment. As shown in FIG. 7, the mold module 21 is detachably provided at the central portion of the upper mold 1A. The mold module 21 has a supply port 11 and a groove 13 extending along the longitudinal direction from the supply port 11. The length of the groove 13 is not particularly limited. However, the groove 13 preferably passes through the central region of the flat portion of the inner surface of the mold. Even when the mold shape is not linear but curved, the groove 13 preferably follows the curved shape change of the mold through the central region of the flat portion.

[0027] FIG. 8 is a diagram showing a second example of the mold module according to the present embodiment. As shown in FIG. 8, a plurality of grooves 14 are provided around the supply port 11 of the mold module 22. The plurality of grooves 14 are composed of a groove extending in the longitudinal direction from the supply port 11 and a plurality of annular grooves surrounding such a groove. Thereby, the lubricating liquid easily flows to a region slightly outside the center of the workpiece 2 where the friction between the mold 1 and the workpiece 2 is likely to increase. In particular, since the positions where the mold module 22 and the workpiece 2 gradually come into contact with each other move from the center to the outside, the lubricating liquid flows appropriately along that position. Thereby, friction can be effectively reduced. The shape and the provided position of the plurality of grooves 14 are not particularly limited. It is preferable that these plurality of grooves do not intersect with each other. By not intersecting the plurality of grooves, as the contact position between the workpiece 2 and the mold 1 moves from the center to the outside, the lubricating liquid can be supplied to the contact position with an appropriate amount and pressure along with the transition.

[0028] FIG. 9 is a view showing a third example of the mold module according to the present embodiment. As shown in FIG. 9, the mold module 23 has a supply port 11 and a groove 13 extending along the longitudinal direction from the supply port 11. Further, an inclined portion 15 is provided which inclines outward from the groove 13 so as to approach the opposing inner surface. That is, the supply port 11 and the groove 13 are provided at the bottom of the inclined portion 15. Thereby, during the hydroforming process, a space is created in which the lubricating fluid accumulates between the workpiece 2 and the supply port 11 provided in the upper die 1A. As the workpiece 2 bulges, the inner surface of the workpiece 2 and the mold 1 try to come into contact in order from the portion close to the supply port 11 in the inclined portion 15. However, the portion close to the supply port 11 is pushed back by the pressure of the lubricating fluid and the workpiece 2 cannot come into direct contact with the mold 1. That is, a complete fluid lubrication state can be created at this portion. As the bulge of the workpiece 2 progresses, since the inclined portion 15 is inclined, the position where the inner surface of the workpiece 2 and the mold 1 come into direct contact moves outward, so that the forming can proceed while expanding the complete fluid lubrication portion.

[0029] FIG. 10 is a diagram showing a fourth example of the mold module according to the present embodiment. As shown in FIG. 9, in the width direction end of the mold module 24 shown in FIG. 9, a plurality of grooves 16 are provided along the longitudinal direction. Such grooves 16 have a function of discharging the lubricating fluid flowing out from the supply port 11. Thereby, in the small surface 17 between the grooves 16, a state with less lubricating fluid can be created. Then, in the portion where a large number of such grooves 16 are arranged, the friction with the workpiece 2 during the hydroforming process can be increased. Since the workpiece 2 contacts the portion of the groove 16 in the latter stage of forming, the flow of the material in the latter stage of forming can be controlled to suppress the deformation of the already deformed portion (the material near the groove 13), and the cracking of the material can be prevented. Note that such grooves 16 can be provided in the mold modules of the other examples described above, or can be directly provided on the upper mold 1A. Further, such grooves 16 may be provided entirely along the longitudinal direction as shown in FIG. 10, or may be provided partially. For example, according to the perimeter (before or after processing) of the workpiece 2, the position where the groove 16 is provided can be appropriately adjusted.

[0030] By using such a mold module that can be attached to and detached from the mold 1, for example, it can be applied to an existing hydroforming processing apparatus. Specifically, in the processing apparatus shown in FIG. 3, by simply adding the lubricating fluid pump 3 and its associated lines, and the mold module to an existing hydroforming processing apparatus, the processing by hydroforming according to the present embodiment becomes possible.

[0031] FIG. 11 is a diagram showing an example of the positional relationship between the mold module according to the present embodiment and the upper mold 1A of the mold 1, and an enlarged view thereof. As shown in FIG. 11, the positions of the surfaces of the mold module 20 and the upper mold 1A may be different. Specifically, the surface of the mold module 20 is preferably protruded more than the surface of the upper mold 1A. The protruding amount D1 is preferably, for example, 0.01 mm or more. Thereby, in the material flow during processing, it is possible to suppress the material from being caught at the boundary between the mold module 20 and the upper mold 1A.

[0032] Also, the distance D2 between the boundary between the mold module 20 and the upper mold 1A and the boundary 18A at the corner portion 18 of the upper mold 1A is preferably within 10 mm. Further, the boundary between the mold module 20 and the upper mold 1A may be inside the corner portion 18. Thereby, the possibility that the workpiece 2 contacts at the boundary between the mold module 20 and the upper mold 1A before the machining of the workpiece 2 is completed can be reduced, and the snagging of the material can be suppressed.

[0033] Note that, as described above, the position where the supply port 11 is provided is preferably provided at the central portion in the longitudinal direction of the mold 1. The supply port 11 is preferably in a region where the perimeter of the cross section orthogonal to the longitudinal direction L of the mold 1 is 1.03 times or more the perimeter of the end of the mold 1 in the longitudinal direction L of the mold 1. FIG. 12 is a diagram for explaining the inner shape of the mold 1 according to the present embodiment and the preferable installation position of the supply port 11. As shown in FIG. 12, when the perimeter C1 of the end 19A of the mold 1 is used as a reference, the supply port 11 is preferably provided in a region where the perimeter C2 of the cross section 19B orthogonal to the longitudinal direction L of the mold 1 is 1.03 times or more the perimeter C1. Since the region where the perimeter C2 is 1.03 times or more the perimeter C1 is a region where the workpiece 2 expands in diameter, the effect of supplying the lubricating liquid from the supply port 11 becomes greater.

[0034] <Supply control of lubricating liquid> Next, an example of the control of the supply of the lubricating fluid will be described. In the present embodiment, during molding, the pressure applied to the workpiece 2 by the lubricating fluid during molding is preferably higher than the processing pressure by the internal pressure fluid supplied to the inside of the workpiece 2. FIG. 13 is a graph showing an example of the supply control of the lubricating fluid and the internal pressure fluid according to the present embodiment. The graph shown in FIG. 13 shows an example of the time-series change of the measured values and set values of the internal pressure applied by the internal pressure fluid and the pressure (lubrication pressure) applied by the lubricating fluid. The timing at which the lubrication pressure (measured value) shown in FIG. 13 rises corresponds to the timing at which the workpiece 2 comes into contact with the surface of the mold 1 and molding starts. Also, before the completion of molding, the supply of the lubricating fluid is stopped at the timing when the lubrication pressure (measured value) drops, and the lubrication pressure is reduced.

[0035] As shown in the graph of FIG. 13, the lubrication pressure (measured value) is controlled to be higher than the internal pressure by the internal pressure fluid from the start of deformation of the workpiece 2 until the supply of the lubricating fluid is stopped. Thereby, while performing the processing by hydroforming, the lubrication state between the mold 1 and the workpiece 2 can be maintained, and the friction can be reduced.

[0036] FIG. 14 is a graph showing another example of the supply control of the lubricating fluid and the internal pressure fluid according to the present embodiment. In the example shown in FIG. 14, the lubricating fluid is controlled to be supplied intermittently. Thus, by deliberately varying the lubrication pressure, the friction between the mold 1 and the workpiece 2 can be deliberately increased during the period when the pressure of the lubricating fluid is decreasing, so that the workpiece 2 can be gripped, and the deformation of the non-contact portion can be promoted. In such supply control, not only the lubrication pressure is repeatedly varied up and down, but it may also be decreased during molding. In this case, the deformation after decreasing the lubrication pressure can preferentially deform the portion not in contact with the mold 1 in the same manner as in normal hydroforming.

Example

[0037] Next, an example according to the present disclosure will be described. Note that the technology shown in this example is merely an example, and the present technology is not limited to the examples described below.

[0038] (Example 1) In this example, the effectiveness of the processing method by hydroforming using the lubricant supply method and control method shown in the above embodiment is shown.

[0039] The processing apparatus by hydroforming used in this example is the processing apparatus and the mold 1 shown in FIGS. 3 to 6. The workpiece 2 is a steel pipe of STKM11A, with an outer diameter Φ of 50.8 mm and a thickness t of 1.2 mm. Such a workpiece 2 is placed in the mold 1. Both the internal pressure liquid and the lubricant used hydraulic oil (viscosity 32). The processing conditions were calculated using the following formula (1). Here, P is the processing pressure, t is the wall thickness of the workpiece 2, σ θ is the maximum tensile stress of the workpiece 2, and r is the curvature of the corner after processing. In this example and the comparative example, processing is performed to deform the central portion in the longitudinal direction of the cylindrical steel pipe into a square pipe having a corner portion of R5. Originally, a pressure of 72 MPa was required to process the steel pipe, but since the maximum pressure of the pump 6 for the internal pressure liquid is 70 MPa, processing was performed at a maximum pressure of 70 MPa.

[0040] P = t×σ θ / r ···(1)

[0041] In the example, during the hydroforming process using the internal pressure liquid, the lubricant was supplied. On the other hand, in the comparative example, only the hydroforming process using the internal pressure liquid was performed, and the lubricant was not supplied. FIG. 15 shows a graph of the pressure control of the internal pressure liquid and the lubricant according to this example. FIG. 16 shows a graph of the pressure control of the internal pressure liquid according to the comparative example. In each case, the output of each pump was manually adjusted for the pressure.

[0042] FIGS. 17 and 18 are diagrams showing the properties of the steel pipes after processing in this example and the comparative example. The steel pipe according to this example shown in FIG. 17 has no particular abnormality, but the surface of the steel pipe according to the comparative example shown in FIG. 18 is broken. Therefore, it is suggested that the supply of the lubricant described above enables the control of the wall thickness during the processing of the steel pipe.

[0043] Figure 19 is a graph showing the wall thickness distribution of the processed steel pipes in this embodiment and the comparative example. The circumferential length L shown on the horizontal axis indicates the position in the circumferential direction when the centers of the opposing vertical walls of the processed steel pipe are used as endpoints respectively. In the comparative example (Conventional), particularly the wall thickness at the center of the wall portion does not decrease, while the wall thickness outside the wall portion decreases (breaks). On the other hand, in this embodiment (proposed), the wall thickness decreases almost uniformly along the circumferential direction, suggesting that the wall thickness is controlled almost homogeneously.

[0044] (Example 2) In this embodiment, an example is shown when the mold module 21 shown in FIG. 7 is applied to the mold 1. Since the processing conditions and the like are the same as those in Example 1, they are omitted.

[0045] Figure 20 is a graph showing the wall thickness distribution of the processed steel pipe in this embodiment. Line 106 is the wall thickness before processing (1.2 mm), and lines 107 - 109 respectively indicate the circumferential lengths (0 mm is the center of the vertical wall, 50 mm is the center of the bottom wall) of the portions at positions 27 mm apart from the central portion in the longitudinal direction of the workpiece 2 (the portion opposite to the supply port 11) along the longitudinal direction. As shown in FIG. 20, since the lubricating liquid is supplied in the longitudinal direction of the mold 1 through the groove 13 provided along the longitudinal direction, there is no difference in the wall thickness distribution between the central portion in the longitudinal direction and the position 27 mm apart. This suggests that it is possible to perform hydroforming processing so as to obtain a uniform wall thickness along the longitudinal direction of the workpiece 2.

[0046] As described above, the preferred embodiments of the present disclosure have been described in detail with reference to the accompanying drawings, but the technical scope of the present disclosure is not limited to such examples. It is obvious that those having ordinary knowledge in the technical field of the present disclosure can conceive of various modification examples or correction examples within the scope of the technical idea described in the claims, and it is naturally understood that these also belong to the technical scope of the present disclosure.

[0047] Also, the effects described in this specification are illustrative or exemplary only and not limiting. That is, the technology according to the present disclosure may exhibit other effects that are apparent to those skilled in the art from the description of this specification, in addition to or instead of the above effects.

[0048] In addition, the following configurations also belong to the technical scope of the present disclosure. (Item 1) An arranging step of arranging a tubular workpiece in a mold formed according to a first direction corresponding to the elongation direction of the workpiece; A lubricant supply step of supplying a lubricant in a central region of a flat portion sandwiched between corner portions of a cross section of the mold in a width direction orthogonal to the first direction of the workpiece on an inner surface of the mold; A forming step of applying pressure from the inside of the workpiece by supplying a liquid from a supply source different from the lubricant while supplying the lubricant, and deforming the workpiece along the inner surface of the mold; A processing method by hydroforming, including: (Item 2) The processing method by hydroforming according to Item 1, wherein a supply port for supplying the lubricant is provided in a central region in a width direction orthogonal to a direction corresponding to the first direction of the mold on the inner surface of the mold. (Item 3) The processing method by hydroforming according to Item 2, wherein the lubricant flowing out from the supply port is supplied only from one supply source. (Item 4) The processing method by hydroforming according to Item 2 or 3, wherein a flow path connecting one or more of the supply ports and one supply source for supplying the lubricant is controlled so that the lubricant is supplied only to any one of the supply ports by a valve. (Item 5) The processing method by hydroforming according to any one of Items 2 to 4, wherein a first groove is provided on the inner surface of the mold along the elongation direction of the mold from the supply port. (Item 6) On the inner surface of the mold, a second groove is provided along the first groove around the first groove. The second groove does not intersect with the first groove, and the processing method by hydroforming according to item 5. (Item 7) The second groove is formed so as to surround the first groove, and the processing method by hydroforming according to item 6. (Item 8) On the inner surface of the mold, at least one third groove is provided toward the outer side in the width direction of the mold of the first groove, and the processing method by hydroforming according to any one of items 5 to 7. (Item 9) The third groove is provided in at least a plurality along the extending direction of the mold, and the processing method by hydroforming according to item 8. (Item 10) The inner surface of the mold is inclined so as to approach the opposing inner surface outward from the supply port, and the processing method by hydroforming according to any one of items 2 to 9. (Item 11) The pressure applied to the workpiece by the lubricating liquid during forming in the forming step is higher than the processing pressure by the liquid supplied to the inside of the workpiece, and the processing method by hydroforming according to any one of items 1 to 10. (Item 12) In the forming step, control is performed to reduce the pressure applied to the workpiece by the lubricating liquid after the start of forming and before the completion of forming, and the processing method by hydroforming according to any one of items 1 to 11. (Item 13) In the forming step, control is performed to vary the pressure applied to the workpiece by the lubricating liquid up and down, and the processing method by hydroforming according to any one of items 1 to 12. (Item 14) The inner surface of the mold is provided with a supply port for supplying the lubricating liquid, and is the surface of a mold module detachably provided on the mold, the processing method by hydroforming according to any one of Items 1 to 13. (Item 15) The mold module is provided so as to protrude from the inner surface of the mold and from the surface where the mold module is not provided, the processing method by hydroforming according to Item 14. (Item 16) A mold for forming a tubular workpiece, The mold has at least one wall portion extending in the longitudinal direction, On the inner surface of the wall portion, a supply port for supplying a lubricating liquid is provided in the central region of a flat surface portion sandwiched between the corner portions of the mold in the width direction orthogonal to the longitudinal direction of the wall portion, the mold. (Item 17) The one supply port is connected only to one supply source via a flow path, the mold according to Item 16. (Item 18) The flow path connecting one or more of the supply ports and one supply source for supplying the lubricating liquid is controlled so that the lubricating liquid is supplied only to any one of the supply ports by a valve, the mold according to Item 16 or 17. (Item 19) On the inner surface of the wall portion, a first groove is provided along the longitudinal direction from the supply port, the mold according to any one of Items 16 to 18. (Item 20) On the inner surface of the wall portion, a second groove is provided along the first groove around the first groove, The second groove does not intersect the first groove, the mold according to Item 19. (Item 21) The second groove is formed so as to surround the first groove, the mold according to Item 20. (Item 22) On the inner surface of the wall portion, at least one third groove is provided toward the outside in the width direction of the wall portion of the first groove, the mold according to any one of Items 19 to 21. (Item 23) The mold according to item 22, wherein at least a plurality of the third grooves are provided along the longitudinal direction of the wall portion. (Item 24) The mold according to any one of items 16 to 23, wherein the inner surface of the wall portion is inclined so as to approach the inner surface of the opposing wall portion outward from the supply port. (Item 25) The supply port is provided in a region where the perimeter of a cross-section orthogonal to the longitudinal direction of the mold is 1.03 times or more the perimeter of the end portion of the mold in the longitudinal direction of the mold. The mold according to any one of items 16 to 24. (Item 26) The inner surface of the mold is the surface of a mold module that includes the supply port and is detachably provided on the mold. The mold according to any one of items 16 to 25. (Item 27) The mold module is provided so as to protrude from the inner surface of the mold at a surface where the mold module is not provided. The mold according to item 26. (Item 28) A mold module that is detachably provided on a flat surface sandwiched between corner portions in the cross-section of the mold, inside the mold for forming a tubular workpiece, On the inner surface of the mold module, a supply port for supplying a lubricating liquid is provided in a central region in the width direction of the mold module. The mold module. (Item 29) A mold having at least one longitudinally extending wall portion, and on the inner surface of the wall portion, a supply port for supplying a lubricating liquid is provided in a central region in the width direction orthogonal to the longitudinal direction of the wall portion, and A lubricating liquid supply source for supplying a lubricating liquid at a position in the central region of a flat surface sandwiched between corner portions in the cross-section of the mold in the width direction orthogonal to the longitudinal direction of the workpiece from the supply port on the inner surface of the mold, An internal pressure liquid supply source for supplying a liquid from a supply source different from the lubricating liquid to the inside of the workpiece while supplying the lubricating liquid to apply pressure from the inside of the workpiece to deform it. A hydroforming processing apparatus comprising

Explanation of Signs

[0049] 1 Mold 2 Workpiece 3 Lubricating fluid pump (lubricating fluid supply source) 6 Internal pressure fluid pump (internal pressure fluid supply source) 11 Supply port 13, 14, 16 Grooves

Claims

1. An arranging step of arranging a tubular workpiece in a mold formed according to a first direction corresponding to the elongation direction of the workpiece; A lubricant supply step of supplying a lubricant in a central region of a flat portion sandwiched between corner portions of a cross section of the mold in a width direction orthogonal to the first direction of the workpiece on an inner surface of the mold; A forming step of applying pressure from the inside of the workpiece by supplying a liquid from a supply source different from the lubricant while supplying the lubricant, and deforming the workpiece along the inner surface of the mold; A processing method by hydroforming, comprising:

2. The processing method by hydroforming according to claim 1, wherein a supply port for supplying the lubricant is provided in a central region in a width direction orthogonal to a direction corresponding to the first direction of the mold on the inner surface of the mold.

3. The processing method by hydroforming according to claim 2, wherein the lubricant flowing out from the supply port is supplied only from one supply source.

4. The processing method by hydroforming according to claim 2 or 3, wherein a flow path connecting one or more of the supply ports and one supply source for supplying the lubricant is controlled so that the lubricant is supplied only to any one of the supply ports by a valve.

5. The processing method by hydroforming according to any one of claims 2 to 4, wherein a first groove is provided on the inner surface of the mold along the elongation direction of the mold from the supply port.

6. A second groove is provided on the inner surface of the mold along the first groove around the first groove, The processing method by hydroforming according to claim 5, wherein the second groove does not intersect the first groove.

7. The processing method by hydroforming according to claim 6, wherein the second groove is formed so as to surround the first groove.

8. The processing method by hydroforming according to any one of claims 5 to 7, wherein at least one third groove is provided on the inner surface of the mold toward the outside in the width direction of the mold of the first groove.

9. The processing method by hydroforming according to claim 8, wherein at least a plurality of the third grooves are provided along the elongation direction of the mold.

10. The inner surface of the mold is inclined so as to approach the opposing inner surface outward from the supply port, the processing method by hydroforming according to any one of claims 2 to 9.

11. The pressure applied to the workpiece by the lubricating liquid during forming in the forming step is higher than the processing pressure by the liquid supplied to the inside of the workpiece, the processing method by hydroforming according to any one of claims 1 to 10.

12. In the forming step, control is performed to reduce the pressure applied to the workpiece by the lubricating liquid after the start of forming and before the completion of forming, the processing method by hydroforming according to any one of claims 1 to 11.

13. In the forming step, control is performed to vary the pressure applied to the workpiece by the lubricating liquid up and down, the processing method by hydroforming according to any one of claims 1 to 12.

14. The inner surface of the mold is provided with a supply port for supplying the lubricating liquid, and is the surface of a mold module detachably provided with the mold, the processing method by hydroforming according to any one of claims 1 to 13.

15. The mold module is provided so as to protrude from the inner surface of the mold and from the surface where the mold module is not provided, the processing method by hydroforming according to claim 14.

16. A mold having at least one wall portion extending in the longitudinal direction, and a supply port for supplying a lubricating liquid is provided in a central region in the width direction orthogonal to the longitudinal direction of the wall portion, A lubricating liquid supply source for supplying the lubricating liquid at a position in the central region of the flat portion sandwiched between the corner portions in the cross section of the mold in the width direction orthogonal to the longitudinal direction of the workpiece, from the supply port on the inner surface of the mold, An internal pressure liquid supply source for supplying a liquid from a supply source different from the lubricating liquid to the inside of the workpiece while supplying the lubricating liquid, and applying pressure from the inside of the workpiece to deform it, A hydroforming processing apparatus comprising.

Images