Roll hemming apparatus and roll hemming method

Abstract

This technology provides excellent fixation strength when two panels are integrally molded using hemming, while suppressing a decline in appearance quality. [Solution] The roll hemming device 20 includes a hemming roller 30 that bends the hemming portion 2 of the outer panel 1 to the main bending position P3 along the inner panel 5 with a hemming adhesive 7 containing glass beads 7a interposed between them, and with the inner panel 5 stacked on top of the outer panel 1. The circumferential surface 31 of the hemming roller 30 is provided with recesses 32 that plastically deform the hemming portion 2 so that a strong pressure portion is formed on the outer panel 1 and the inner panel 5 when the hemming roller 30 presses against the hemming portion 2 at the main bending position P3, causing the glass beads 7a to bite into both the outer panel 1 and the inner panel 5, and a general pressure portion is formed on the outer panel 1 and the inner panel 5, where a pressure lower than the strong pressure portion is applied.

Description

Technical Field

[0001] The present invention relates to a roll hemming device and a roll hemming method.

Background Art

[0002] The following Patent Document 1 discloses a conventional roll hemming method for folding back the hemming portion of the outer panel of a vehicle door of an automobile and integrating it with the inner panel. In this roll hemming method, generally, the outer panel is set in a lower die with the inner panel overlaid, and the hemming portion, which is the edge of the outer panel, is pressed while being bent toward the inner panel side by a hemming roller called a hem roll provided at the tip of a robot arm.

[0003] In this roll hemming method, a hemming roller provided with convex portions on its circumferential surface is used. The outer panel and the inner panel are clamped by the convex portions of the hemming roller being press-fitted into the hemming portion of the outer panel and the inner panel. In this case, it is necessary to press the convex portion of the hemming roller extremely locally against the hemming portion to form a concave portion, and for this purpose, the pressing force input from the hemming roller to the hemming portion of the outer panel becomes large. If the pressing force at this time becomes too large, it is known that the appearance quality of the product deteriorates.

[0004] Therefore, in order to suppress the pressing force input to the hemming portion of the outer panel, it is effective to use the hemming adhesive sealing method for vehicle body panels described in the following Patent Document 2. In this adhesive sealing method, a hemming adhesive containing glass beads is used with an intervening layer between the outer panel and the inner panel. In this case, an appropriate pressing force that allows the glass beads to moderately bite into both the outer panel and the inner panel may be input from the hemming roller to the hemming portion of the outer panel. Therefore, there is an advantage that the pressing force input from the hemming roller to the hemming portion can be overall suppressed lower compared to the case of Patent Document 1.

Prior Art Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2013-46930 [Patent Document 2] Japanese Patent Publication No. 2004-26070 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] In the adhesive sealing method described in Reference 2, when a constant pressure is simply applied to the hemming portion of the outer panel from the hemming roller, if the pressure is not appropriate, problems may arise such as the tip of the hemming portion of the outer panel lifting up due to insufficient pressure, making it impossible to ensure the fixing strength between the outer panel and the inner panel, or the panel deforming due to excessive pressure, resulting in a decrease in appearance quality. Therefore, there is a need to develop a hemming processing technology suitable for using hemming adhesives containing glass beads.

[0007] This invention has been made in view of the above problems, and aims to provide an excellent technology for ensuring fixing strength when two panels are integrally molded by hemming, while suppressing a deterioration in appearance quality. [Means for solving the problem]

[0008] One aspect of the present invention is, A roll hemming apparatus for integrally molding a first panel and a second panel, A hemming roller is used to bend the hemming portion, which is the edge of the first panel, to the main bending position along the second panel while the second panel is placed on top of the first panel with a hemming adhesive containing glass beads interposed between them. A roller head that rotatably holds the hemming roller and is attached to a robot arm, Equipped with, A roll hemming device is provided, on the circumferential surface of the hemming roller, recesses are provided to plastically deform the hemming portion such that a strong pressure portion is applied to the first panel and the second panel when the hemming roller is pressed against the hemming portion at the bending position, causing the glass beads to bite into both the first panel and the second panel, and a general pressure portion is applied to the first panel and the second panel, where a pressure lower than that of the strong pressure portion is applied. It is located there.

[0009] Other aspects of the present invention include: A roll hemming method for integrally molding a first panel and a second panel, The first step involves placing the second panel on top of the first panel with a hemming adhesive containing glass beads interposed between them, A second step involves moving a hemming roller having a recess on its circumferential surface with a robot arm to bend the hemming portion, which is the edge of the first panel, from an upright position to a pre-bending position. A third step involves moving the hemming roller with the robot arm to bend the hemming portion from the preliminary bending position to the main bending position along the second panel, thereby sandwiching the second panel, and plastically deforming the hemming portion by the recess so that a strong pressure section is formed on the first panel and the second panel, and a general pressure section is formed on the first panel and the second panel, where a pressure less than that of the strong pressure section is applied, and the hemming portion is plastically deformed by the recess, A roll hemming method having It is located there. [Effects of the Invention]

[0010] In the roll hemming apparatus or roll hemming method described above, when the hemming roller is pressed and rolled in accordance with the movement of the robot arm at the main bending position of the hemming portion of the first panel, the plastic deformation action of the hemming portion due to the recess provided on its circumferential surface can cause a strongly pressurized portion and a generally pressurized portion to be formed in the first panel and the second panel.

[0011] In the highly pressurized areas, the glass beads contained in the hemming adhesive bite into both the first and second panels, generating the clinching force necessary to prevent the decomposition of the first and second panels. In these highly pressurized areas, excessive pressure is not required to locally plastically deform the hemming portion of the first panel itself to bite into the second panel. By keeping the pressure within a range that does not affect the appearance quality, it is effective in preventing a deterioration of the appearance quality. In contrast, in the general pressurized areas, the deterioration of the molded product's appearance quality can be suppressed by reducing the pressure compared to the highly pressurized areas. Even if the applied pressure is reduced in the general pressurized areas, the desired clinching force can be secured in the highly pressurized areas. In this way, it is possible to prioritize appearance quality by suppressing overall pressure, while prioritizing crimping only in the localized highly pressurized areas to ensure the necessary fixing strength.

[0012] As described above, each of the embodiments described above makes it possible to provide an excellent technology for ensuring the fixing strength when two panels are integrally molded by hemming, while suppressing a deterioration in appearance quality. [Brief explanation of the drawing]

[0013] [Figure 1] A diagram showing the overall structure of the panel molding equipment according to Embodiment 1. [Figure 2] A perspective view of a molded body in which the outer panel and inner panel are integrally molded. [Figure 3] A perspective view of the hemming roller of the roll hemming apparatus of Embodiment 1. [Figure 4] A flowchart of the roll hemming method according to Embodiment 1. [Figure 5]Side view showing the state of the first step of FIG. 4. [Figure 6] Side view showing the state of the second step of FIG. 4. [Figure 7] Side view showing the state of the third step of FIG. 4. [Figure 8] Perspective view showing the state of the third step of FIG. 4. [Figure 9] Perspective view showing an enlarged part of FIG. 8. [Figure 10] Cross-sectional view taken along the line X-X of FIG. 9. [Figure 11] Plan view of FIG. 9 as viewed from above. [Figure 12] Side view showing the state when measuring the clinching force of the molded body of FIG. 2. [Figure 13] Perspective view of the hemming roller according to the comparative example.

Mode for Carrying Out the Invention

[0014] Preferred embodiments of the above-described aspect will be described below.

[0015] In the roll hemming device of the above-described aspect, a pair of the recesses adjacent to each other at intervals in the circumferential direction are provided on the circumferential surface of the hemming roller, and in the first panel and the second panel, the general pressure portion is formed at a portion facing the recess, and it is preferably configured such that the strong pressure portion is formed at a portion facing the intermediate portion between the pair of the recesses.

[0016] According to this roll hemming device, in the first panel and the second panel, the general pressure portion can be formed at a portion facing each of the pair of recesses of the hemming roller, and the strong pressure portion can be formed at a portion facing the intermediate portion between the pair of recesses.

[0017] In the roll hemming device of the above-described aspect, it is preferable that the shape of the recess when the hemming roller is viewed from the radially outer side is circular.

[0018] This roll hemming device allows for lower processing costs when creating recesses on the circumferential surface of the hemming roller by making the recesses circular in shape.

[0019] In the roll hemming apparatus according to the above-described embodiment, it is preferable that the recess of the hemming roller has an inner diameter that exceeds half the length dimension of the width dimension from the tip of the hemming portion to the bent end.

[0020] According to this roll hemming device, the inner diameter of the recess of the hemming roller is set to exceed half the length dimension of the width dimension from the tip of the hemming portion to the bent end of the first panel. Then, by pressing and rolling the hemming roller so that the recess does not exceed the intermediate position between the tip of the hemming portion and the bent end at the bending position, the recess of the hemming roller moves in an overlapping manner with the tip of the hemming portion. This ensures that the tip of the hemming portion is securely crimped by the hemming roller to prevent it from opening, and also prevents the part of the hemming portion closer to the bent end from being crushed and looking bad due to the recess of the hemming roller exceeding the intermediate position and getting too close to the bent end of the hemming portion.

[0021] In the roll hemming method according to the above-described embodiment, the circumferential surface of the hemming roller is provided with a pair of adjacent recesses spaced apart in the circumferential direction, and it is preferable that the first panel and the second panel have a general pressurizing portion formed in the portion facing the recess and a strong pressurizing portion formed in the portion facing the intermediate portion between the pair of recesses.

[0022] According to this roll hemming method, in the first and second panels, general pressure areas can be formed in the portions facing each of the pair of recesses of the hemming roller, and strong pressure areas can be formed in the portions facing the intermediate portion between the pair of recesses.

[0023] In the roll hemming method according to the above embodiment, it is preferable that the shape of the recess is circular when viewed from the radially outward direction of the hemming roller.

[0024] This roll hemming method allows for lower processing costs when creating recesses on the circumferential surface of the hemming roller by making the recesses circular in shape.

[0025] In the roll hemming method according to the above-described embodiment, the recess of the hemming roller has an inner diameter exceeding half the length dimension of the width dimension from the tip to the bent end of the hemming portion, and in the third step, when the hemming portion is viewed from the thickness direction, it is preferable to press and roll the hemming roller so that the recess passes through a pressing range enclosed by a first boundary line extending along the tip in the longitudinal direction of the hemming portion and a second boundary line extending parallel to the first boundary line at an intermediate position in the short direction of the hemming portion.

[0026] According to this roll hemming method, the inner diameter of the recess of the hemming roller is set to exceed half the length dimension of the width dimension from the tip of the hemming portion of the first panel to the bent end. Then, the hemming roller is pressed and rolled so that the recess passes through the pressing area enclosed by the first boundary line and the second boundary line, causing the recess of the hemming roller to overlap with the tip of the hemming portion as it advances. This ensures that the tip of the hemming portion is securely crimped by the hemming roller to prevent it from opening, and also prevents the part of the hemming portion closer to the bent end from being crushed and looking bad due to the recess of the hemming roller going too far beyond the intermediate position and getting too close to the bent end of the hemming portion.

[0027] The roll hemming apparatus and roll hemming method described above will be explained below with reference to the drawings.

[0028] (Embodiment 1) 1. Configuration of the panel molding equipment 101 The panel molding equipment 101 according to Embodiment 1, shown in Figure 1, is equipment for forming a molded body W shown in Figure 2 from an outer panel 1, which is a first panel, and an inner panel 5, which is a second panel. This panel molding equipment 101 includes a lower mold 10, a roll hemming device 20, a robot 50, and a control panel 60.

[0029] Both the outer panel 1 and the inner panel 5 are made of steel plate. The molded body W is used, for example, as various parts that make up the body of an automobile. Examples of molded bodies W include vehicle doors made of the outer panel 1 and the inner panel 5, and vehicle hoods and trunks made of the outer panel 1 and the inner panel 5.

[0030] The lower mold 10 is a mold for stacking and setting the inner panel 5 on top of the outer panel 1. At this time, the inner panel 5 is stacked on top of the outer panel 1 with hemming adhesive 7 interposed between them. The outer panel 1 is pre-formed using known lower blades, pads, and bending blades (all not shown) so that the hemming portion 2, which is its edge, is in an upright position that is roughly perpendicular to the main body. The hemming portion 2 of the outer panel 1 is also called the "flange portion" or "edge portion".

[0031] The Hemming adhesive 7 contains multiple glass beads 7a. The glass beads 7a are spheres formed by processing soda-lime glass or borosilicate glass into a spherical shape. There are no particular limitations on the average particle size, content ratio, or composition of the Hemming adhesive 7 of the glass beads 7a. As an example of glass beads 7a, those with an average particle size in the range of 100 to 300 μm and a content ratio in the range of 0.3 to 2% by weight can be used. Also, as an example of the Hemming adhesive 7, a one-component epoxy adhesive consisting of epoxy resin (bisphenol-type epoxy resin, urethane-modified epoxy resin, acrylic rubber-modified epoxy resin, polyalkylene ether-modified epoxy resin, etc.) and a latent curing agent can be used. In addition, polyurethane-based or acrylic-based adhesives containing glass beads 7a may also be used.

[0032] 2. Structure of the roll hemming device 20 The roll hemming device 20 is a processing device or processing tool for integrally forming the outer panel 1 and the inner panel 5. This roll hemming device 20 is equipped with a hemming roller 30 and a roller head 40.

[0033] The hemming roller 30 is used to bend the hemming portion 2 of the outer panel 1 from the upright position (see "upright position P1" in Figure 5) to the final bending position (see "final bending position P3" in Figure 7) along the inner panel 5, with the inner panel 5 superimposed on the outer panel 1 via hemming adhesive 7. This bending process is also called "roll hemming."

[0034] The roller head 40 rotatably holds the hemming roller 30. The roller head 40 has a built-in spring 41 for spring-pressurizing the hemming roller 30 so that it can extend and retract. The roller head 40 is attached to the tip of the robotic arm 51 of the robot 50.

[0035] The robot 50 in this configuration is a teaching playback type articulated robot in which an arm with multiple axes that move vertically is attached to a base that rotates horizontally. The control panel 60 is equipped with a control unit 61 for controlling the robot 50. According to this control unit 61, the position and orientation of the hemming roller 30 held by the roller head 40 are appropriately adjusted by controlling the position and orientation of the tip of the robot arm 51.

[0036] As shown in Figure 3, the hemming roller 30 is a cylindrical or cylindrical member and is held by the roller head 40 so as to be rotatable around the central axis 30a. The circumferential surface 31 of the hemming roller 30 is provided with a pair of adjacent recesses 32, 32 spaced apart in the circumferential direction C. The circumferential surface 31 of the hemming roller 30 may have one pair of recesses 32, 32, or multiple pairs. The shape and size of the recesses 32 when viewed radially outward from the hemming roller 30 are not particularly limited, but in this embodiment, an example is given in which the shape of the recesses 32 is circular considering the machinability of the circumferential surface 31.

[0037] The pair of recesses 32, 32 exert the effect of plastically deforming the hemming portion 2 so that a strongly pressurized portion Sa (see Figures 9 and 10) and a general pressurized portion Sb (see Figures 9 and 10) are formed side by side on the outer panel 1 and the inner panel 5 when the hemming roller 30 pressurizes and rolls against it at the main bending position P3, as described later. Alternatively, only one recess 32 may be provided on the circumferential surface 31 of the hemming roller 30, provided that a similar effect is obtained.

[0038] 3. Roll hemming method The roll hemming method of Embodiment 1 is a method for forming a molded body W (see Figure 2) by integrally molding an outer panel 1 and an inner panel 5. In this roll hemming method, the steps from the first step S101 to the third step S103 in Figure 4 are executed sequentially. Note that additional steps may be added as needed, or at least one step may be divided into multiple steps.

[0039] 3-1. Panel stacking process The first step S101 in Figure 4 is a panel stacking process in which the inner panel 5 is stacked on top of the outer panel 1 with hemming adhesive 7 interposed between them, as shown in Figure 5. At this time, the outer panel 1 has the hemming portion 2 pre-bent to the upright position P1 and is placed on the upper surface of the lower die 10. At this time, the upright position P1 is the position in which the hemming portion 2 extends approximately perpendicularly to the main body portion 1a of the outer panel 1 when viewed from the X-axis direction. Meanwhile, the edge portion 6 of the inner panel 5 is temporarily joined to the main body portion 1a of the outer panel 1 via the hemming adhesive 7 at a position close to the hemming portion 2.

[0040] 3-2. Preliminary bending process The second step S102 in Figure 4 is carried out following the first step S101. As shown in Figure 6, this second step S102 is a preliminary bending process in which the hemming portion 2 of the outer panel 1 is bent from the upright position P1 shown by the dashed line to the preliminary bending position P2 shown by the solid line by moving the hemming roller 30 with the robot arm 51.

[0041] In the second step S102, the robot arm 51 is controlled to move the hemming roller 30 in the bending direction A while simultaneously moving it back and forth once or multiple times in the X-axis direction, with the circumferential surface 31 of the hemming roller 30 pressed against the surface of the hemming section 2.

[0042] In the second step S102, the hemming roller 30 buckles the hemming portion 2 in the bending direction A from the upright position P1 to the preliminary bending position P2, centering on the R-shaped bent end 2b. The preliminary bending position P2 is the position where, when the hemming portion 2 is viewed from the X-axis direction, the hemming portion 2 extends at an angle of approximately 45° relative to the edge portion 6 of the inner panel 5.

[0043] Furthermore, in the second step S102, the hemming roller 30 rolls in a pressing motion due to friction with the hemming section 2 as it moves in the X-axis direction. Here, "pressing motion" refers to the movement in which the hemming roller 30 rotates around the central axis 30a by rolling on the surface of the hemming section 2 while in a pressing motion.

[0044] Furthermore, in this second step S102, when the hemming roller 30 is moved in the bending direction A, the reaction force that its circumferential surface 31 receives from the hemming portion 2 is weaker than that during crimping in the main bending process described later. Therefore, the recess 32 of the hemming roller 30 itself hardly participates in the plastic deformation of the hemming portion 2. Consequently, the hemming roller 30 having a recess 32 on its circumferential surface 31 is advantageous in that it can be used not only in the main bending process but also in the preliminary bending process.

[0045] 3-3. Main bending process The third step S103 in Figure 4 is carried out following the second step S102. As shown in Figure 7, this third step S103 is the main bending process in which the hemming roller 30 is moved by the robot arm 51 to bend the hemming portion 2 of the outer panel 1 from the preliminary bending position P2 shown by the dashed line to the main bending position P3 shown by the solid line, so that it is sandwiched by the edge portion 6 of the inner panel 5, and the hemming roller 30 is pressed and rolled against the hemming portion 2.

[0046] In the third step S103, similar to the second step S102, the robot arm 51 is controlled to move the hemming roller 30 in the bending direction A while simultaneously moving it in the X-axis direction, with the circumferential surface 31 of the hemming roller 30 pressed against the hemming portion 2. According to this third step S103, the edge 6 of the inner panel 5 is sandwiched between the main body 1a of the outer panel 1 and the hemming portion 2, crushing the hemming portion 2. The pressure applied by the hemming roller 30 at this time is controlled by the amount of expansion and contraction (compression) of the spring 41. As a result, the outer panel 1 and the inner panel 5 are crimped together and integrated.

[0047] In the third step S103, the hemming roller 30 buckles the hemming portion 2 in the bending direction A from the preliminary bending position P2 to the main bending position P3, centered on the bent end 2b. The main bending position P3 is the position where, when the hemming portion 2 is viewed from the X-axis direction, the hemming portion 2 is folded back along the edge 6 of the inner panel 5, extending approximately parallel to the edge 6. At the main bending position P3, the hemming portion 2 has its longitudinal direction in the X-axis direction and its short direction in the Y-axis direction.

[0048] Furthermore, in the third step S103, the hemming roller 30 rolls by friction with the hemming section 2 as it moves in the X-axis direction. At this time, as shown in Figure 8, by moving the tip of the robot arm 51 uniformly in the X-axis direction, the hemming roller 30 moves in the X-axis direction from, for example, the first rolling position Q1 to the second rolling position Q2.

[0049] Here, the first rolling position Q1 is the position in which the surface of the hemming roller 30 other than the recess 32 is pressed against the surface of the hemming portion 2. In contrast, the second rolling position Q2 is the position in which the surface of the hemming roller 30 including the recess 32 is pressed against the surface of the hemming portion 2.

[0050] In this embodiment, there is no need to change the movement of the robot arm 51 in the pressing direction when the hemming roller 30 is in the first rolling position Q1 or the second rolling position Q2. It is sufficient to simply move the hemming roller 30 uniformly in the X-axis direction while maintaining a constant distance from the central axis 30a of the hemming roller 30 to the hemming portion 2. At this time, the reaction force received by the circumferential surface 31 of the hemming roller 30 from the hemming portion 2 becomes stronger than during the preliminary bending process in the second step S102, resulting in the recess 32 participating in the plastic deformation of the hemming portion 2. This point will be explained below.

[0051] As shown in Figure 9, when the hemming roller 30 presses and rolls at the main bending position P3 of the hemming portion 2, a pair of recesses 32, 32 on the circumferential surface 31 form a strongly pressurized area Sa and a general pressurized area Sb side by side in the X-axis direction on the outer panel 1 and the inner panel 5. The strongly pressurized area Sa is a region where the applied pressure is stronger than that of the general pressurized area Sb. The pair of recesses 32, 32 in this embodiment exert the effect of plastically deforming the hemming portion 2 in such a way that it creates areas where the hemming portion 2 of the outer panel 1 is strongly pressed locally.

[0052] First, a portion of the material of the hemming section 2 escapes into the recess 32 of the hemming roller 30, forming a general pressure section Sb in the outer panel 1 and inner panel 5 in the area facing the recess 32. On the other hand, in the outer panel 1 and inner panel 5, a strong pressure section Sa is formed in the area facing the intermediate section 33 between the pair of recesses 32, 32, where the pressure toward the edge 6 of the inner panel 5 increases due to the wrinkling caused by the pressure recovery of the material of the hemming section 2 (see arrow in Figure 10). In short, the strong pressure section Sa is formed so as to face the surface of the circumferential surface 31 of the hemming roller 30 that is away from the recess 32.

[0053] According to this embodiment, there is an advantage that a strongly pressurized section Sa and a general pressurized section Sb can be formed on the outer panel 1 and the inner panel 5 without moving the robot arm 51 on the equipment side in the pressing direction, simply by making an ingenious modification such as providing a pair of recesses 32, 32 on the circumferential surface 31 of the hemming roller 30.

[0054] As shown in Figure 10, the high-pressure area Sa is a region where pressure is applied to cause the glass beads 7a contained in the hemming adhesive 7 to bite into both the main body 1a of the outer panel 1 and the edge 6 of the inner panel 5. In this high-pressure area Sa, the glass beads 7a scratch and catch on the surfaces of both the main body 1a of the outer panel 1 and the edge 6 of the inner panel 5. The biting of the glass beads 7a generates a clinching force necessary to prevent the outer panel 1 and the inner panel 5 from shifting or disassembling. In addition, in this high-pressure area Sa, the hemming adhesive 7 prevents the entry of liquid from the outside.

[0055] In contrast, the general pressure area Sb is a region where a lower pressure is applied than in the strong pressure area Sa, and where the glass beads 7a do not bite into both the main body 1a of the outer panel 1 and the edge 6 of the inner panel 5. With this general pressure area Sb, the lower pressure compared to the strong pressure area Sa makes it possible to suppress the deterioration of appearance quality that occurs due to an increase in pressure.

[0056] In this embodiment, when the outer panel 1 and inner panel 5 are viewed in cross-section as shown in Figure 10, a highly pressurized area Sa is locally formed between the two general pressurized areas Sb due to the plastic deformation action of the hemming area 2 by the pair of recesses 32, 32. With one rotation of the hemming roller 30, the highly pressurized area Sa, which is an extreme pressure area, is formed at one location.

[0057] As shown in Figure 11, the inner diameter d1 of the recess 32 of the hemming roller 30 can be set based on the width dimension D from the tip 2a to the bent end 2b of the hemming portion 2 of the outer panel 1. For example, it is preferable that the recess 32 has an inner diameter d1 that exceeds half the length dimension of the width dimension D. In this case, it is preferable that the dimension d2 of the intermediate portion 33 between the pair of recesses 32, 32 in the X-axis direction or circumferential direction C (see Figure 3) be about half the length dimension of the inner diameter d1 of the recess 32. Also, in the third step S103 of Figure 4, it is preferable to press the hemming roller 30 against the hemming portion 2 so that the pair of recesses 32, 32 pass through the pressing range M enclosed by the first boundary line L1 and the second boundary line L2. Here, the first boundary line L1 is a virtual straight line extending along the tip 2a in the X-axis direction, which is the longitudinal direction of the hemming portion 2. On the other hand, the second boundary line L2 is a hypothetical straight line that extends parallel to the first boundary line L1 at an intermediate position in the Y-axis direction, which is the shorter direction of the hemming portion 2.

[0058] In the third step S103, when the hemming portion 2 is viewed from the Z-axis direction, which is the thickness direction, the hemming roller 30 is pressed against the hemming portion 2 and rolled so that the pair of recesses 32, 32 on the circumferential surface 31 of the hemming portion 2 overlap with the tip 2a of the hemming portion 2 and advance in the X-axis direction. At this time, since the pair of recesses 32, 32 reliably pass through the tip 2a of the hemming portion 2, the strongly pressurized portion Sa can be expanded to the tip 2a side in the Y-axis direction, preventing the tip 2a of the hemming portion 2 from lifting up and opening, which would compromise the fixing strength between the outer panel 1 and the inner panel 5.

[0059] Furthermore, in the third step S103, when the hemming portion 2 is viewed from the Z-axis direction, the hemming roller 30 is pressed and rolled against the hemming portion 2 so that the pair of recesses 32, 32 on the circumferential surface 31 of the hemming roller 30 do not extend beyond the second boundary line L2 and protrude towards the bent end 2b of the hemming portion 2, and do not move in the X-axis direction. This prevents a decrease in the appearance quality of the R-shaped bent end 2b due to the pair of recesses 32, 32 passing through an area closer to the bent end 2b of the hemming portion 2 than the pressing range M.

[0060] The shape and size of the recess 32 are preferably set appropriately according to the clinch force between the outer panel 1 and the inner panel 5. This clinch force is also called the "bonding force" or "crimping force". For example, the shape of the recess 32 may be changed from a circle to an ellipse or a semicircle. The clinch force between the outer panel 1 and the inner panel 5 can be measured for a pre-fabricated sample molded body Wa according to the clinch force measurement method described below, and the shape and size of the recess 32 can be set based on the measurement results.

[0061] 4. Method for measuring clinch force As shown in Figure 12, when measuring the clinch force between the outer panel 1 and inner panel 5 of a sample molded body Wa, first, the sample molded body Wa is placed and fixed on the inspection stand 11. This fixing can be done by the operator directly gripping the sample molded body Wa, or it can be done using a fixing jig. The distance in the Y-axis direction from the end of the sample molded body Wa (the bent end 2b of the hemming portion 2) to the front surface 11a of the stand 11 is the backing dimension dr of the stand 11. The clinch force measurement is performed when the end of the sample molded body Wa overhangs the stand 11 by the backing dimension dr. The backing dimension dr is set appropriately based on the structure and part of the sample molded body Wa. In this embodiment, the backing dimension dr can be set to a value of, for example, 50 to 100 mm.

[0062] Next, with the hook portion 12a of the measuring jig 12 hooked onto the tip 2a of the hemming portion 2 of the outer panel 1, the operator pulls the push-pull gauge 13 connected to the jig 12 downwards. At this time, the value displayed on the push-pull gauge 13 when the hemming portion 2 is displaced by an amount Δd from the main bending position P3 to the displacement position P4 becomes the measured value of the clinching force.

[0063] If the measured clinch force reaches the control standard value, the hemming roller 30 used in the production of the sample molded body Wa can be used in the production of the actual product. On the other hand, if the measured clinch force falls below the control standard value, the clinch force measurement is performed again on another sample molded body Wa produced using a hemming roller 30 with a different shape and size of recess 32. The measurement of the clinch force can then be continued by changing the sample molded body Wa until the measured value reaches the control standard value.

[0064] 5. Comparative Examples Here, referring to Figure 13, the disadvantages of the comparative example hemming roller 30A will be explained in comparison with the advantages of the hemming roller 30 of Embodiment 1. The hemming roller 30A has a circular protrusion 35 on its circumferential surface 31 instead of the recess 32 of the hemming roller 30. In order to make the protrusion 35 bite into the hemming portion 2, a material with higher hardness than the hemming roller 30 itself and the lower mold 10 is used for the material of this protrusion 35. The other structures are the same as those of the hemming roller 30.

[0065] 5-1. Impact of dry firing When using the roll hemming device 20 during maintenance or adjustment, or when performing a so-called "dry run," if a workpiece is not set in the lower die 10, there is a concern that the protrusions 35 of the hemming roller 30A may damage the lower die 10 because they are made of a material with higher hardness than the lower die 10. In contrast, the hemming roller 30 has no protrusions on its circumferential surface 31, so even when performing a dry run, it has the advantage of not damaging the lower die 10 with any protruding parts.

[0066] 5-2. Impact during processing When the hemming roller 30A presses against the hemming portion 2 of the outer panel 1, the protrusions 35 become areas that generate additional pressure. Therefore, the alternating action of areas with and without protrusions 35 on the hemming portion 2 becomes a factor that causes vibration. In contrast, the hemming roller 30 has the advantage of preventing the generation of vibration during pressing and rolling because it does not have a convex shape on its circumferential surface 31.

[0067] 5-3. Maintainability The hemming roller 30A is prone to wear because the protrusions 35 on its circumferential surface 31 locally interfere with the hemming portion 2 of the outer panel 1, requiring replacement at regular intervals. In contrast, the hemming roller 30 does not have a protrusion shape on its circumferential surface 31, resulting in less wear on the circumferential surface 31. This has the advantage of significantly extending the replacement cycle compared to using the hemming roller 30A.

[0068] 5-4. Versatility Because the hemming roller 30A has protrusions 35 on its circumferential surface 31, there is a concern that using it in the preliminary bending process (see Figure 6) may cause dents or cracks on the surface of the hemming portion 2 of the outer panel 1 due to the protrusions 35. Therefore, in light of this, the hemming roller 30A is difficult to use in the preliminary bending process and is basically dedicated to the main bending process (see Figure 7). In this case, it is necessary to prepare a separate processing tool for use in the preliminary bending process. In contrast, the hemming roller 30 does not have a protrusion shape on its circumferential surface 31 and presses the hemming portion 2 over a wide area of ​​the circumferential surface 31, so in the preliminary bending process the hemming portion 2 can be bent with a weaker pressure than when crimping in the main bending process. Therefore, the hemming roller 30 can be used in both the preliminary bending process and the main bending process, and has the advantage of being highly versatile.

[0069] 5-5. Simplicity of structure The hemming roller 30A requires the use of methods such as embedding hard material or build-up welding to create the protrusions 35 on its circumferential surface 31, which raises concerns about the complexity of its internal structure. In contrast, the hemming roller 30 has the advantage of a simple structure because it only requires post-processing to create recesses 32 on its circumferential surface 31.

[0070] 6. Effects According to Embodiment 1 described above, the following effects and advantages can be obtained.

[0071] According to the hemming roller 30 of Embodiment 1, when the hemming portion 2 of the outer panel 1 is pressed and rolled in accordance with the movement of the robot arm 51 at the main bending position P3, the plastic deformation action of the hemming portion 2 by the recess 32 provided on its circumferential surface 31 causes a strongly pressurized portion Sa and a generally pressurized portion Sb to be formed on the outer panel 1 and the inner panel 5.

[0072] In the highly pressurized section Sa, the glass beads 7a contained in the hemming adhesive 7 bite into both the outer panel 1 and the inner panel 5, generating the clinching force necessary to prevent displacement and disintegration of the outer panel 1 and the inner panel 5. Furthermore, in this highly pressurized section Sa, excessive pressure such as that required to locally plastically deform the hemming portion 2 of the outer panel 1 itself to bite into the inner panel 5 is unnecessary. By keeping the pressure within a range that does not affect the appearance quality, it is effective in preventing a deterioration of the appearance quality. In contrast, in the general pressurized section Sb, the deterioration of the appearance quality of the molded body W can be suppressed by reducing the pressure compared to the highly pressurized section Sa. Even if the applied pressure in the general pressurized section Sb is reduced, the desired clinching force can be secured in the highly pressurized section Sa. In this way, the overall pressure can be kept low to prioritize appearance quality, while crimping can be prioritized only in the localized highly pressurized section Sa to ensure the necessary fixing strength.

[0073] As described above, Embodiment 1 provides an excellent technology for ensuring the fixing strength when two panels 1 and 5 are integrally molded by hemming, while suppressing a deterioration in appearance quality.

[0074] According to Embodiment 1, in the outer panel 1 and the inner panel 5, a general pressurized portion Sb can be formed in the portion facing each of the pair of recesses 32, 32 of the hemming roller 30, and a strong pressurized portion Sa can be formed in the portion facing the intermediate portion 33 between the pair of recesses 32, 32.

[0075] According to Embodiment 1, by making the shape of the recess 32 of the hemming roller 30 circular, the processing cost when machining the recess 32 on the circumferential surface 31 of the hemming roller 30 can be kept low.

[0076] According to Embodiment 1, the inner diameter d1 of the recess 32 of the hemming roller 30 is set to exceed half the length dimension of the width dimension from the tip 2a to the bent end 2b of the hemming portion 2 of the outer panel 1. Then, the hemming roller 30 is pressed and rolled so that the recess 32 passes through the pressing range M enclosed by the first boundary line L1 and the second boundary line L2, that is, so that the recess 32 does not go beyond the intermediate position between the tip 2a and the bent end 2b of the hemming portion 2. This causes the recess of the hemming roller to overlap with the tip of the hemming portion as it advances. As a result, the tip of the hemming portion 2 can be reliably crimped by the hemming roller 30 to prevent it from opening, and the effect of the recess 32 of the hemming roller 30 going too far beyond the intermediate position and getting too close to the bent end 2b of the hemming portion 2 can be suppressed, which would cause the part of the hemming portion 2 closer to the bent end 2b to be crushed and look bad.

[0077] The present invention is not limited to the typical embodiments described above, and various applications and modifications are conceivable as long as they do not depart from the purpose of the invention. For example, the following embodiments can be implemented by applying the embodiments described above.

[0078] In the above-described embodiment, an example was given of integrally forming the outer panel and inner panel, which are body panels, by hemming. However, the above-described embodiment can also be applied to integrally forming two panels other than the body panels by hemming. [Explanation of Symbols]

[0079] 1…Outer panel (first panel), 2…Hemming section, 2a…Tip, 2b…Bent end, 5…Inner panel (second panel), 7…Hemming adhesive, 7a…Glass beads, 10…Lower mold, 20…Roll hemming device, 30…Hemming roller, 31…Circumferential surface, 32…Recess, 40…Roller head, 51…Robot arm, C…Circumferential direction, d1…Inner diameter, D…Width dimension from tip of hemming section to bent end, L1…First boundary line, L2…Second boundary line, M…Pressing range, P1…Upright position, P2…Preliminary bending position, P3…Main bending position, Sa…Strong pressure section, Sb…General pressure section, S101…First step, S102…Second step, S103…Third step, S101~S103…Roll hemming method, X…Longitudinal direction, Y…Short direction

Claims

1. A roll hemming apparatus for integrally molding a first panel and a second panel, A hemming roller is used to bend the hemming portion, which is the edge of the first panel, to the main bending position along the second panel while the second panel is placed on top of the first panel with a hemming adhesive containing glass beads interposed between them. A roller head that rotatably holds the hemming roller and is attached to a robot arm, Equipped with, A roll hemming device, wherein the circumferential surface of the hemming roller is provided with recesses that plastically deform the hemming portion such that a strong pressure portion is formed on the first panel and the second panel, and a general pressure portion is formed on the first panel and the second panel, where a pressure lower than that of the strong pressure portion is applied, when the hemming roller is pressed against the hemming portion at the bending position.

2. The roll hemming apparatus according to claim 1, wherein the circumferential surface of the hemming roller is provided with a pair of adjacent recesses spaced apart in the circumferential direction, and the first panel and the second panel are configured such that the general pressurizing portion is formed in the portion facing the recesses, and the strong pressurizing portion is formed in the portion facing the intermediate portion between the pair of recesses.

3. The roll hemming apparatus according to claim 1 or 2, wherein the recess has a circular shape when viewed radially outward from the hemming roller.

4. The roll hemming device according to claim 3, wherein the recess of the hemming roller has an inner diameter that exceeds half the length dimension of the width dimension from the tip of the hemming portion to the bent end.

5. A roll hemming method for integrally molding a first panel and a second panel, The first step involves placing the second panel on top of the first panel with a hemming adhesive containing glass beads interposed between them, The second step involves bending the hemming portion, which is the edge of the first panel, from an upright position to a pre-bending position by moving a hemming roller having a recess on its circumferential surface with a robot arm, A third step involves moving the hemming roller with the robot arm to bend the hemming portion from the preliminary bending position to the main bending position along the second panel, thereby sandwiching the second panel, and plastically deforming the hemming portion by the recess so that a strong pressure section is formed on the first panel and the second panel, and a general pressure section is formed on the first panel and the second panel, where a pressure less than that of the strong pressure section is applied, and the hemming portion is plastically deformed by the recess, A roll hemming method having

6. The roll hemming method according to claim 5, wherein the circumferential surface of the hemming roller is provided with a pair of adjacent recesses spaced apart in the circumferential direction, and in the first panel and the second panel, the general pressurizing portion is formed in the portion facing the recess, and the strong pressurizing portion is formed in the portion facing the intermediate portion between the pair of recesses.

7. The roll hemming method according to claim 5 or 6, wherein the recess has a circular shape when viewed from the radially outward direction of the hemming roller.

8. The recess of the hemming roller has an inner diameter that exceeds half the length dimension of the width dimension from the tip of the hemming portion to the bent end, The roll hemming method according to claim 7, wherein, in the third step, when the hemming portion is viewed from the thickness direction, the hemming roller is pressed and rolled so that the recess passes through a pressing area enclosed by a first boundary line extending along the tip in the longitudinal direction of the hemming portion and a second boundary line extending parallel to the first boundary line at an intermediate position in the short direction of the hemming portion.

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