JP4970900B2 - Press working method and molding apparatus used therefor - Google Patents

Description

The present invention relates to a press working method and forming shapes device Ru use therein.

JP 2004-195535 A JP 2004-314132 A Japanese Patent Laid-Open No. 2004-174551 Presentation materials of the 2006 plastic working spring lecture 41-42 "Development of shape freezing technology by compression-Development of technology for application of super high-tensile parts-" Makoto Hyori (Toyota Motor), etc. Nippon Steel Technical Report No. 378 (2003) pp. 25-29 “Frozenness improvement technology for high-strength steel sheets” Satoshi Yoshida et al. JP 2003-94118 A JP 2000-271665 A

  In press molding of a hat bent shape product having a flange portion, a spring back is generated due to press processing, so that the shape freezing property with respect to the mold shape is low. In particular, high-strength steel sheets used recently for automobile parts have a large amount of springback. For this reason, it is necessary to correct the mold with a so-called trial error while confirming the final shape, and the production efficiency is low. As a method for reducing the influence of the spring back, a method of correcting a product deformation with respect to the mold shape generated in the bending drawing step by adopting a barrel piercing (restricting) step after the bending drawing step is adopted. Further, Patent Document 1 proposes a method for suppressing springback based on various theories.

  For example, in Patent Document 1, when a metal plate is formed into a U-shaped or L-shaped cross section, the spring back is alleviated by once bending over to a desired bending angle after being once bent over a desired bending angle. Proposed method. That is, the bending back of the vertical wall portion once overbended is bent back to release the residual stress, thereby reducing the spring back of the vertical wall with respect to the top plate.

  Patent Document 2 discloses that when a molded product having a hat-shaped cross section is press-molded, a gap is formed between the base portion of the punch and the die to cause an overrun phenomenon in the metal plate, and the punch is doubled up and down. Among them, a forming method is proposed in which a metal plate after overrun is bent back with a lower punch. This method is also a method of reducing the residual stress when the vertical wall is drawn, making the vertical wall angle with respect to the top plate accurate, and reducing warpage.

  Patent Document 3 discloses a method for forming a hat-shaped cross-sectional component in which warp of a vertical wall is reduced by drawing using a punch that does not use a blank holder, and finally bending a flange portion. Since this method does not use a blank holder at the time of drawing, it does not go through a step of bending back, thereby reducing warpage.

  Non-Patent Document 1 discloses that a compression force is applied in the longitudinal direction of a workpiece during bending in order to improve the shape freezing property by suppressing spring back when forming a car part by hat bending a high-tensile steel plate. A technique for applying and applying a uniform compressive strain across the front and back of the board is disclosed.

  Non-Patent Document 2 details the generation mechanism of springback, and refers to the tension control of the vertical wall by overrun. Furthermore, Non-Patent Document 2 introduces as a prior art a method in which the heel pressing force is reduced at the initial stage of bending drawing and the heel pressing force is increased at the final stage of processing to make a final pressing. Non-Patent Document 2 states that this method is difficult to realize with a normal press, and then performs a fixed pressing process following bending drawing and also uses a variable bead molding at the time of the fixed pressing process. We have proposed a method of applying the cusp at the time of die cutting as coining at the time of final pressing.

  On the other hand, Patent Document 4 uses a lower die and an upper die in which three blocks on the left and right and the center are combined, and a bending drawing die that can form a plurality of types of products by exchanging the central block. Is disclosed. Patent Document 5 also discloses a similar block rearranging hydroforming mold.

  Since the processing methods of Patent Document 1 and Patent Document 2 perform bending processing and bending back processing, it is necessary to perform processing in two steps using different molds. For this reason, two molds are required and two presses are used, so that the cost of equipment and tools is increased. It is possible to arrange two dies on a single press and process them using a transfer device such as a transfer device. However, the die height of the bending draw die and the die height of the bending back die are usually different. It takes time and effort to match them, and a transport device is required. In addition, the processing method of Patent Document 3 also requires two types of molds: drawing and flange bending.

  On the other hand, the processing method of Non-Patent Document 1 can complete the processing by one processing (one stroke of the slide), but in order to apply a compressive force in the longitudinal direction of the workpiece, A special molding technique is required, such as restraining the metal with a guide, and a special mold is required. Since Non-Patent Document 2 performs bending drawing processing and fixed pressing processing in that order, there is a merit that the conventional molding technique and mold can be used almost as they are, but two steps are required as in Patent Documents 1 to 3. Furthermore, since the die height is different between the bending drawing die and the fixed pushing die, there is the same problem as described above.

  In Patent Documents 4 and 5, two types of products having different dimensions can be manufactured with only one mold. That is, the shape of the mold can be changed. However, since it cannot be changed in the middle of processing, it is deformed while being removed from the press. Further, the type of molding cannot be changed, and only the partial dimensions of the same drawing are changed.

The present invention combines the idea of changing the dies described in Patent Documents 4 and 5 with the processing method that performs the bending drawing process and the depressing process described in Non-Patent Document 2, and can be applied to different moldings with one mold. It is a technical problem to provide a press working method capable of performing bending drawing forming and barrel piercing forming (determining pressing) in order with the same mold. The present invention is directed to an object to provide a text that formed form devices such pressing method.

The press working method of the present invention is a press working method in which a drawing process or a bending drawing process and a body bump forming process are performed in this order, and the drawing process or the bending drawing process is performed by a punch, a die, and a punch or a die. By means of a drawing die or a bending drawing die provided with a contact member that is provided on either one so as to be vertically movable and abuts against the other through a workpiece, and means for limiting / releasing the vertical stroke of the contact member . 1 by pressing up to the bottom dead center, and the upper and lower strokes of the abutment member are limited to the drum mold or the bending diaphragm without taking out the workpiece from the diaphragm or bending diaphragm. In this way, the workpiece is changed to a barrel die and pressed to the second bottom dead center so as to clamp the workpiece (Claim 1) . The position of the first bottom dead center and the position of the second bottom dead center are usually different, but may be the same. In such a press working method, it is preferable that the pressurization by the first bottom dead center and the pressurization by the second bottom dead center are performed during one stroke of the slide by a servo press.

The pre-Symbol abutment member, the blank holder and provided adjacent to the punch (or) preferably knockout member provided inside the die (claim 3). Further, the means for restricting / releasing the up / down stroke is limited to an interposition member provided movably between a restriction position interposed between the abutting member and the die set and a release position not interposed. It is preferable to comprise a moving means for moving between the position and the release position (claim 4 ).

A molding apparatus according to the present invention (Claim 5 ) includes a punch, a die, a contact member that is provided on one of the punches and the die so as to be vertically movable, and abuts against the other via a workpiece, and the contact member under and the flop-less provided with a means for limiting / releasing the upper and lower stroke consists of a servo press which sets its press die, the servo press is first in a state that does not limit the stroke of the contact member It is characterized by being configured to pressurize to the dead point and pressurize to the second bottom dead center in a restricted state . In such a forming apparatus, it is preferable that the contact member is a blank holder provided adjacent to the punch and / or a knockout member provided inside the die (claim 6 ).

Further, the means for restricting / releasing the vertical stroke includes an interposition member provided movably between a restriction position interposed between the contact member and the die set and a release position not interposed, and the interposition member. It is preferable to include a moving means for moving between the restriction position and the release position (Claim 7 ).

The press working method of the present invention uses a die that can be deformed from a drawing die or a bending drawing die to a barrel piercing die, and after the bending step or bending drawing step, the same die is deformed into a drum piercing die. Perform the barrel molding process. At that time, the work after the drawing process or the bending drawing process is not taken out and is left in the mold as it is. For this reason, the workpiece is not displaced, and deformation due to processing in the drawing process or the bending drawing process does not occur. Therefore, galling or seizure that occurs when the work is pushed into the mold in the barrel piercing process is unlikely to occur. Further, the manufacturing and management costs of the mold can be saved, and the work for taking out the workpiece from the mold and supplying the mold to the mold is small, so that the press working is easy. Further, each process itself may be a conventional drawing or bending drawing and barrel molding, and it is not necessary to add a special function other than deforming the mold. Therefore, advanced technology is also unnecessary.
Further, in the press working method of the present invention, at the time of drawing or bending drawing, the vertical stroke of the abutting member is not limited, but the drawing or bending drawing is performed, and then the vertical stroke of the abutting member is limited, The workpiece can be clamped between the abutting member and the other side to perform barrel piercing. Therefore, the punch, the die and the contact member can be used for both moldings, and the deformation of the mold for each process is small.

  In the case where the pressurization by the first bottom dead center and the pressurization by the second bottom dead center are performed by one servo press during one stroke of the slide (Claim 2), the drawing process or the bending drawing process and the barrel molding process are performed. Even when the die height is different, it can be processed with one press, and the molding time is short.

When the contact member is a blank holder provided adjacent to the punch and / or a knockout member provided inside the die (Claim 3 ), the blank holder and / or the knockout member are drawn or formed. The original action in the bending drawing and the clamping action in the barrel molding can be achieved, and the mold can be simply configured.

The means for restricting / releasing the vertical stroke includes an interposition member that is movably provided between a restriction position interposed between the abutting member and the die set and a release position not interposed, and the interposition member is restricted to the restriction position. And a moving means for moving between the release position (Claim 4 ), no pressing force is applied to the moving means. Therefore, the structure of a moving means becomes easy. Moreover, the interposition member can also be made into the simple form which can receive the up and down applied pressure.

The molding apparatus according to the present invention (Claim 5 ) is a drawing mold or a bending drawing mold that is pressed to the first bottom dead center, so that the vertical stroke of the contact member is not limited. Ru can be performed bend draw forming. And by changing the press die to Dozuki mold, by pressurizing to the second bottom dead center to limit the vertical stroke of the contact member performs Dozuki molded to nipped the workpiece between the contact member and the other be able to. Therefore, the punch, the die and the contact member can be used for both moldings, and the deformation of the mold for each process is small.
Depending on the characteristics of the servo press, the first bottom dead center and a second bottom dead center different from the first bottom dead center can be applied during one slide stroke. Therefore, both moldings can be reliably performed within a short time. Furthermore, since both bottom dead center positions can be made different, an appropriate die height can be selected for each molding.

In such a forming apparatus , when the abutting member is a blank holder provided adjacent to the punch and / or a knockout member provided inside the die (Claim 6 ), the blank holder and / or With the knockout member, the original action in drawing or bending drawing and the pinching action in barrel molding can be achieved by a single unit, and the mold can be configured easily.

The means for restricting / releasing the vertical stroke includes an interposition member provided movably between a restriction position interposed between the abutting member and the die set and a release position not interposed, and the interposition member is placed at the restriction position. And the moving means for moving between the release positions (claim 7 ), the pressing force is not applied to the moving means. Therefore, the structure of a moving means becomes easy. Moreover, the interposition member can also be made into the simple form which can receive the up and down applied pressure.

Next will be described a press working method Contact and molding apparatus of the present invention with reference to the drawings. 1A and 1B are a plan view and an end view showing an example of a molded product processed by the press working method of the present invention, FIG. 2 is a perspective view of the molded product, and FIG. 3 is used for the press working method of the present invention. 4 is a cross-sectional view showing an embodiment of a bending drawing mold, FIG. 4 is a cross-sectional view showing a state in which the bending drawing mold of FIG. 3 is deformed into a barrel type, and FIGS. 5 and 6 show the procedure of the press working method of the present invention. FIG. 7 is a sectional view showing an embodiment of a press die used in the press working method of the present invention, and FIGS. 8a and 8b show an embodiment of an operating state of a servo press used in the press working method of the present invention. FIG. 9A and FIG. 9B are a slide motion diagram and a crank shaft rotation operation diagram, respectively, and FIG. 9A and FIG. 9B show another embodiment of the operating state of the servo press used in the press working method of the present invention. A rotation operation diagram.

  First, referring to FIGS. 1a, 1b, and 2, the bending drawing process and the barrel molding process will be described. In addition, it can replace with a bending drawing process and can also perform the simple drawing process which does not include a bending process. In simple bending, the influence of the springback can be reduced only by adjusting the bending angle, so it is not necessary to employ the method of the present invention. In the bending drawing step, a blank 10 obtained by punching a flat metal plate into a predetermined shape is formed into an intermediate molded product 11 having a hat-shaped cross section (first step). In the body butt molding process, the intermediate molded product 11 obtained in the bending drawing process is re-molded to obtain a final molded product (second process). Here, as shown in FIG. 1 b, the “hat type” means a top surface 13, left and right side walls 14 extending downward from the left and right ends of the top surface, and a flange 15 extending outward from the lower ends of the side walls 14. It is the shape provided with. Actually, processes such as a trimming process and a drilling process are added as necessary after the second process.

  As shown in FIG. 1a, the blank 10 has a substantially "<" shape that is curved or bent in the middle, and the intermediate molded product 11 and the final molded product have a hat-shaped cross section as shown in FIG. It becomes a continuous form with substantially the same cross-sectional shape in the axial direction while curving. If the bend line is a straight line, it can be processed by simple bending, but it is curved in the middle, so that drawing is necessary at that portion. In addition, even if there is no curved part in the middle, in order to form a hat type with a flange part in one step, the flange is formed with a blank holder (claw presser), so the molding is similar to drawing.

 The material of the blank 10 is not particularly limited, but in order to effectively utilize the advantage of suppressing the spring back according to the present invention, for example, a high-strength steel plate having a tensile strength of 590 to 1470 MPa, aluminum, etc., the spring back is large in normal processing. Is preferred. The plate | board thickness of the blank material 10 is about 0.5-3.0 mm, for example.

  The bending draw depth in the first step can be set to be equal to the final molded product size, and the deformation amount due to the spring back can be corrected in the second step to obtain the final molded product size. The depth of bending drawing (h1 in FIG. 3) is formed by about 1 to 6 mm or about 2 to 5 mm deeper than the depth of the final molded product (h2 in FIG. 4) (h1> h2). Conversely, the bending drawing depth may be made shallower than the final product depth (h1 <h2). The width B of the intermediate molded product and the final molded product is the same.

  The first step can be performed by, for example, the bending drawing die 20 of FIG. The bending drawing die 20 includes a lower die 21 and an upper die 22. The lower die 21 includes a lower die set 23, a punch 24 fixed to the lower die set 23, a blank holder (saddle presser) 25 arranged so as to be movable up and down so as to surround the punch 24, and A cushion pin 26 fixed to the lower surface, penetrating the lower die set 23, and biased upward by a die cushion (not shown) at the lower end is provided.

  The upper die 22 has an upper die set 28, a holder 30 fixed to the lower surface of the upper die set 28 via a spacer 29, and is fixed to the lower surface of the holder 30. The punch 24 is sandwiched between workpieces during processing. , A knockout 32 accommodated in the die 31 and the holder 30 so as to be movable up and down, and the knockout 32 is suspended and held through the upper die set 28 with a spring or the like not shown. And a knockout pin 33 that is biased by. A step portion 34 is provided on the inner surface of the holder 30 and can be engaged with a step portion 35 formed on the outer surface of the knockout 32.

  The mold 20 includes a punch 24, a die 31, a blank holder 25 and a knockout 32 as functional parts for creating a target product shape, and upper and lower parts as structural parts related to the size of the target product and the press machine used. The die sets 28 and 23, guide posts (not shown), guide bushes that slide along the guide posts, and holders such as the holder 30 and the spacer 29 described above can be roughly divided.

  FIG. 3 shows a schematic structure at the first bottom dead center of the press. At this bottom dead center, the height h1 protruding from the blank holder 25 of the punch 24 is the workpiece depth of the intermediate molded product 11 by the bending drawing process. That's it. A first space 37 is provided between the upper surface of the lower die set 23 and the lower surface of the blank holder 25, and a second space 38 is provided between the lower surface of the upper die set 28 and the upper surface of the knockout 32. ing. The dimension H1 from the lower surface of the lower die set 23 to the upper surface of the upper die set 28 in a state where the flange 15 of the intermediate molded product 11 is interposed between the die 31 and the blank holder 25 is the die height. This die height is the dimension between the bolster and the slide at the bottom dead center of the slide of the press. In actual press forming, the bottom dead center position of the slide is set to make the drawing depth and the dimension of the flange 15 accurate. is important.

  The bending draw die 20 configured as described above is such that the lower die 21 is fixed to the bolster of the press, the upper die 22 is fixed to the slide, and the slide is raised (step S0 in FIGS. 3 and 5). The intermediate molded product 11 can be molded by placing a blank material (10 in FIG. 1a) on the blank holder 25 and moving the slide up and down. That is, as the slide descends from step S0 in FIG. 5, the die 31 sandwiches the periphery of the blank with the blank holder 25. At that time, the central region of the blank is sandwiched between the upper surface of the punch 24 and the lower surface of the knockout 32. When the slide is further lowered, the portion of the blank 11 sandwiched between the work die 31 and the blank holder 25 slides between the outer surface of the punch 24 and the inner surface of the die 31 to form the side wall 14 (step of FIG. 5). A). At that time, the portion once bent at the corner at the lower end of the inner surface of the die 31 is extended again as it enters between the die 31 and the punch 24. As a result, internal distortion occurs in the workpiece, causing spring back.

  During the lowering of the slide, the central region of the blank is pressed against the upper surface of the punch 24 by the urging force of the knockout pin 33. The peripheral portion of the blank material slides inward while being pressed between the die 31 and the blank holder 25 by the urging force of the die cushion. As a result, the side wall 14 is not wrinkled. In addition, when the biasing force of the die cushion is too strong, the workpiece is cut, and when it is too weak, the workpiece is wrinkled. Therefore, the relationship between the urging force of the die cushion and the stroke is important. In the case of a normally used bellows type die cushion, the initial urging force or the urging force at the bottom dead center can be adjusted to some extent by adjusting the air pressure, but cannot be controlled over the entire stroke. Therefore, when it is desired to increase the pull-in resistance of the blank material, a resistance portion such as a bead is provided on the upper surface of the blank holder.

After the hat-shaped intermediate molded product 11 is formed as described above, the slide of the press rises halfway (step CD in FIG. 6). At that time, the left and right side walls 14 of the intermediate molded product 11 are spring-backed so that the lower end side is expanded. Thereby, the intermediate molded product 11 strongly adheres to the die 31, but the intermediate molded product 11 is pushed downward by the urging force of the knockout 32. The blank holder 25 which has been pressed by the die 31 with increasing slide is raised by the biasing force of the die cushion, the intermediate molded article 11 is also withdrawn from the punch 24. At this time, the raising amount of the blank holder 25 is also regulated by the locking device of the die cushion and rises only halfway.

  At this time, the lift stroke of the slide can be made larger than the bending drawing depth h1 of the intermediate molded article 11, but it is preferable to make it smaller. For example, the ascending stroke of the slide is set to about [(h1-h2) + α] mm. α is, for example, about 3 to 7 mm. Thereby, the clearance gap which inserts the upper and lower body thrust plates 40 and 39 is made.

  Further, the rising amount of the blank holder 25 is limited by limiting the rising amount of the die cushion with a locking device or the like. In that case, even if the upper die 22 is raised as in step CD of FIG. 6, the blank holder 25 is raised only to a position lower than the upper surface of the punch 24, and the intermediate molded product 11 is placed around the punch 24. Remains covered. That is, the intermediate molded product 11 is not completely removed from the punch 25, and the lower part is maintained in a state of being fitted to the outer periphery of the punch 25. Therefore, the positioning of the intermediate molded product 11 is reliable in the next cylinder piercing molding process. Further, the inner surface of the intermediate molded product 11 and the punch 25 and the outer surface of the intermediate molded product 11 and the die 31 are hardly in sliding contact, and galling and seizure can be prevented. Further, it is possible to avoid a situation where the intermediate molded article 11 raises the knockout 32 and the gap into which the upper slide piece 47 enters is closed.

  After the bending drawing process of FIG. 3 is completed, the barrel piercing process is performed using the same mold as shown in FIG. However, before this process, that is, during the CD process of FIG. 6, the lower drum plate 39 is inserted into the first space 37 between the lower die set 23 and the blank holder 25, and the upper die set 28, the knockout 32, The upper drum plate 40 is inserted into the second space 38 between the two. When the slide of the press is lowered in this state, the die 31 and the blank holder 25 are lowered while sandwiching the flange. Molding is performed (step B in FIG. 6).

  Similarly, the knockout 32 and the punch 24 are lowered in a state where the top surface 13 of the intermediate molded product 11 is clamped, and the upper barrel plate 40 prevents the knockout 32 from being raised near the bottom dead center of the press, and the slide is dead. Do the barrel molding at the point. Thereby, a finished product having a high shape freezing property in which the spring back of the workpiece is suppressed is obtained. As described above, actually, trimming and punching are performed after this.

  After the cylinder butt molding of FIG. 4, the slide of the press rises and returns to the step S0 of FIGS. In this state, the workpiece is taken out, and the upper and lower body thrust plates 40 and 39 are taken out. Then, a new blank material is placed on the blank holder 25 and the next bending drawing process is performed.

  In the molding of FIGS. 5 and 6, the press may be a normal press, in which case it is stopped at the top dead center for each raising and lowering of the press, and the upper and lower barrel plates 40 and 39 are inserted between them, Or take it out. In addition, when the die height is different between the bending drawing process and the body butt molding process, the bottom dead center position of the press is changed (die height adjustment). For servo presses, it is only necessary to change the bottom dead center position setting. As a mechanism to convert the rotation of the servo motor into the vertical movement of the slide, in addition to the normal crank (crank press), these are combined such as a link (link press), a screw (screw press) or a ball screw + knuckle link press. Any of these mechanisms can be employed.

  The mold 42 shown in FIG. 7 automatically inserts and removes the above-described upper and lower body thrust plates 40 and 39. The left side of FIG. 7 shows the state of the bottom dead center of the bending drawing process, and the right side shows the state of the bottom dead center of the barrel piercing process. In this mold 42, a lower slide piece 43 slidably disposed on the lower die set 23 is used instead of the lower barrel thrust plate 39, and the lower slide piece 43 is connected to the tip of the rod 45 of the air cylinder 44. ing. Thereby, the lower slide piece 43 is configured to be driven between a position where it does not interfere with the blank holder 25 (left side in FIG. 5) and a position where it interferes (right side).

  In this embodiment, in order to shorten the moving stroke of the lower slide piece 43, a notch 46 is provided on the lower surface of the blank holder 25, and the blank holder 25 is not removed from the lower side of the blank holder 25. To avoid interference. Further, when the air cylinder 43 is extended (right side in FIG. 7), the lower slide piece 43 is positioned as close as possible to the punch 24. Thereby, the pressure applied to the blank holder 25 below the flange 15 of the intermediate molded product 11 can be efficiently transmitted to the lower die set 23.

  Further, an upper slide piece 47 provided so as to be slidable along the upper die set 28 is employed in place of the upper trunk projection plate 40 of FIG. The upper slide piece 47 is fixed to the tip of the rod 49 of the air cylinder 48. The upper slide piece 47 moves above the knockout 32 when the air cylinder 48 is extended (right side in FIG. 7), and retracts to a position where it does not interfere with the knockout 32 when contracted (left side in FIG. 7). ). Since the other points are substantially the same as the mold 20 of FIGS. 3 and 4, the same reference numerals are given to the same portions, and the detailed description is omitted.

  In the mold 42 shown in FIG. 7, a taper portion 50 or a rounded portion (small-diameter curved portion) is provided at the boundary portion between the side wall 14 and the flange 15 of the intermediate molded product 11 during the bending drawing step, and the taper portion is formed during the cylinder thrusting step. 50 is crushed into a part of the flange. And in order to obtain the crushing allowance at that time, the bottom dead center position of the blank holder 25 is made higher in the cylinder thrusting process than in the bending drawing process. Similarly, at the boundary portion between the side wall 14 and the top surface 13, a tapered portion 51 or a rounded portion is provided in the bending drawing process, and the tapered portion 51 or the rounded portion is crushed into a part of the top surface 13 in the cylinder thrusting process. . Therefore, the bottom dead center position of the upper die set 28 is also higher than that in the bending drawing process. Since the depth h2 of the finished product 12 is shallower than the drawing depth h1 of the intermediate molded product 11, the bottom dead center position of the knockout 32 is the same in both steps. However, as a whole, the die height H2 in the barrel piercing process is higher than the die height H1 in the bending drawing process.

  On the other hand, it is also possible to perform the barrel molding while bending the tapered portion or the rounded portion of the boundary portion between the side wall 14 and the flange 15 or the boundary portion between the side wall 14 and the top surface 13 toward the side wall 14 side. In that case, the drawing depth h2 in the cylinder piercing step becomes deeper than the drawing depth h1 in the first bending bending step. Then, the bottom dead center of the die 31 in the barrel piercing process is lower than the bottom dead center of the die 31 in the bending drawing process. For this reason, the die height H2 in the barrel piercing process may be lower than the die height H1 in the bending drawing process.

  From the above, it may be considered that the die height H1 in the first step and the die height H2 in the second step are the same in some cases. In that case, there is no need to adjust or change the die height. However, normally, since it is formed into a predetermined shape in the bending drawing process, it is necessary to adjust the die height appropriately according to the manufactured mold, and similarly, it is necessary to adjust the die height also in the barrel piercing process. For this reason, generally, the die height H1 in the first step and the die height H2 in the second step are either H1 <H2 or H1> H2.

  In order to efficiently and continuously press while changing the height of such a die height, it is preferable to use a servo press capable of arbitrarily setting a slide motion, for example, as shown in FIGS. 8a and 8b. 8a and 8b show the case where the die height H1 in the first step is lower than the die height H2 in the second step. The graph of FIG. 8a shows the relationship between time (horizontal axis) and slide position (vertical axis). The slide descending from the top dead center reaches the first bottom dead center at the position of symbol A while performing bending drawing, rises to the position of symbol C, and temporarily stops at that position.

  In view of the crank angle in FIG. 8b, the crankshaft rotates from 0 ° to 180 ° (S1), and further overruns by an angle corresponding to A-C in that direction (S2) and stops at that position (S3). ). 8a is inserted between the blank holder 25 and the lower die set 23, and the upper slide piece 47 is inserted between the knockout 32 and the upper die set 28. Insert between. Then, after the insertion of the upper and lower slide pieces 47 and 43 is completed, the crankshaft is reversely rotated by rotating the motor reversely to lower the slide (S4), and the motor is stopped when the point B is reached. . It can be seen that the crankshaft in FIG. 8b rotates in the reverse direction from point C to point B. This point B is the second bottom dead center. After being lowered to the second bottom dead center B, the crankshaft is rotated again in the original rotational direction to drive the slide to the top dead center (S5). In this processing method, the die height H1 in the first step is lower than the die height H2 in the second step by “H2-H1”.

  As described above, the servo press can control the rotational speed and direction of the motor on the way, so that two bottom dead centers can be realized during one slide stroke. The process can be performed. Therefore, it is possible to efficiently perform the bending drawing process and the cylinder piercing process continuously. In addition to the servo press, a screw press or a hydraulic press capable of precise control of the stroke can be used, but the servo press is most preferable from the viewpoint of production efficiency.

  9a and 9b show the slide motion and crank angle state when the bottom dead center A of the first step is higher than the bottom dead center B of the second step. In this stroke motion, the crankshaft is first rotated by an angle smaller than 180 ° (S11), and a bending drawing process is performed at that position. Next, the crankshaft rotates in the opposite direction (S12) and stops at that position (S13). Then, the slide frame is moved while stopped. Next, the crankshaft is rotated in the original normal rotation direction (S14), and the cylinder piercing process is performed at the bottom dead center (second bottom dead center) B of the press. Thereafter, the crankshaft is rotated in the forward direction to reach the top dead center of the press (S15). In this processing method, it is possible to perform the bending drawing step and the barrel piercing step with a mold in which the die height in the first step is higher by “H1-H2” than the die height in the second step. The other points are the same as those in FIGS. 8a and 8b.

  In the above embodiment, the upper and lower slide pieces 47 and 43 are driven by the air cylinder, but may be driven by a hydraulic cylinder. Also, other driving means such as a solenoid actuator or a motor can be employed. Driving means such as an air cylinder can take a timing such as expansion and contraction by outputting a signal from the control device of the servo press. For safety, it is preferable that an interlock is applied so that the second step is started after the slide pieces 47 and 43 complete the movement.

  In the above-described embodiment, the upper slide piece 47 or the upper barrel butt plate 40 is directly interposed between the knockout 32 and the upper die set 28. However, a slide plate or the like for improving sliding is used as the knockout 32 or the upper die set 28 or both. And may be interposed between them. In the above-described embodiment, the upper slide piece 47 or the upper body thrust plate 40 is used to limit / release the vertical stroke of the knockout 32. However, a member that restricts / releases the rise of the knockout pin 33 is, for example, The upper and lower strokes of the knockout may be limited / released by another mechanism such as provided on the die set 28 or on the upper side thereof.

  Similarly, for the lower slide piece 43 or the lower body thrust plate 39, a slide plate or the like for improving sliding may be provided in the blank holder 25 or the lower die set 23 and interposed therebetween. Further, the vertical stroke of the blank holder 25 may be limited / released by another mechanism such as a member for restricting / releasing the vertical stroke of the cushion pin 26, for example, on the lower die set 23 or the lower side thereof.

  3 or 7, the top surface of the intermediate product 11 is the knockout 32 and is merely pressed by the spring biasing force that biases the knockout downward. In order to mark the top surface of the intermediate product 11, the surface may be lightly pressed (cushioning) at the bottom dead center of the press. The drawing process and the bending drawing process of claim 1 include the case of performing such light surface pressing.

  In normal processing, trimming (trim forming) and piercing (piercing forming) are performed after the right barreling step in FIG. 4 or FIG. 7, but these can be performed by different presses or by the same press. . Since the slide stroke required for trimming and piercing is about the plate thickness, it is relatively easy to match the die height. In addition, when machining with two bottom dead centers of the first bottom dead center and the second bottom dead center with the servo motor as shown in FIG. 8 or FIG. 9, in the middle of the first bottom dead center and the second bottom dead center. Trimming or piercing is preferred. Thereby, it is possible to prevent the trim die (die) or the piercing punch from hitting the material twice (entering the material twice).

1a and 1b are a plan view and an end view, respectively, showing an example of a molded product processed by the press working method of the present invention. It is a perspective view of the molded article of FIG. It is sectional drawing which shows one Embodiment of the bending drawing die used for the press work method of this invention. It is sectional drawing which shows the state which deform | transformed the bending drawing type | mold of FIG. It is sectional drawing which shows one Embodiment of the press die used for the press work method of this invention. 8a and 8b are a slide motion diagram and a rotational operation diagram of a crankshaft showing an embodiment of an operating state of a servo press used in the press working method of the present invention, respectively. 9a and 9b are a slide motion diagram and a rotation operation diagram of the crankshaft showing another embodiment of the operating state of the servo press used in the press working method of the present invention, respectively.

Explanation of symbols

10 Blank material 11 Intermediate molded product 12 Final molded product 13 Top surface 14 Side wall 15 Flange 20 Bending drawing die 21 Lower die 22 Upper die 23 Lower die set 24 Punch 25 Blank holder 26 Cushion pin 28 Upper die set 29 Spacer 30 Holder 31 Die 32 Knockout 33 Knockout pin 34 Step 35 Step 37 First space 38 Second space 39 Lower barrel thrust plate 40 Upper barrel thrust plate 42 Mold 43 Lower slide piece 44 Air cylinder 45 Rod 46 Notch 47 Upper slide piece 48 Air cylinder 49 Rod 50 Tapered part 51 Tapered part

Claims (7)

A press working method that performs a drawing process or a bending drawing process and a body bump forming process in that order,
The squeezing step or bending squeezing step is carried out by a punch, a die, a punch member or a die that is provided so as to be vertically movable, and a contact member that makes contact with the other through a workpiece, and a vertical stroke of the contact member By pressing to the first bottom dead center with a drawing die or a bending drawing die having means for restricting / releasing
The cylinder piercing step is changed to a cylinder piercing die by restricting the vertical stroke of the abutting member without taking out the workpiece from the drawing die or bending drawing die. Pressing method in which the workpiece is clamped by applying pressure to the bottom dead center.   2. The press working method according to claim 1, wherein the pressurization by the first bottom dead center and the pressurization by the second bottom dead center are performed during one slide stroke by a servo press. The press working method according to claim 1 or 2 , wherein the contact member is a blank holder provided adjacent to the punch and / or a knockout member provided inside the die. The means for restricting / releasing the vertical stroke includes an interposition member that is movably provided between a restriction position interposed between the abutting member and the die set and a release position not interposed, and the interposition member is restricted to the restriction position. 4. The press working method according to claim 1, 2 or 3, comprising a moving means for moving between the position and the release position. A punch, a die, a contact member that is provided on either the punch or the die so as to be movable up and down, and abuts against the other through a workpiece, and means for limiting / releasing the up / down stroke of the contact member and the flop-less was,
It consists of a servo press with the press mold set,
A molding apparatus in which the servo press is configured to pressurize to the first bottom dead center in a state where the stroke of the contact member is not limited, and pressurize to the second bottom dead center in a limited state . The molding apparatus according to claim 5 , wherein the contact member is a blank holder provided adjacent to the punch and / or a knockout member provided inside the die. The means for restricting / releasing the vertical stroke includes an interposition member provided movably between a restriction position interposed between the abutting member and the die set and a release position not interposed, and the interposition member is placed at the restriction position. 7. A molding apparatus according to claim 5 or 6, comprising a moving means for moving between the release position and the release position.

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