KR101591874B1 - Double cross pad of upper die for compensating deformation after stamping automotive structure panel and method thereof - Google Patents

Abstract

)으로 길이가 긴 자동차 차체 패널의 멤버 및 레일류와 같은 형태의 자동차 차체 패널을 프레스 성형하는 과정에서 리스트라이킹 공정이 필요 없는 더블 크로스 패드 금형 구조를 개발함으로써 드로잉 또는 포밍과정에서 치수 변형을 잡으면, 리스트라이크 공정을 삭제할 수 있는 각별한 장점이 있는 유용한 발명이다.The present invention relates to an apparatus and a method for correcting an automobile body panel mold by a double cross pad mold structure, which comprises an upper die (10); A blank 20 provided at the bottom of the upper die 10; A plurality of punches 30 disposed at the bottom of the blank 20 and positioned at lower portions thereof and having height differences such that molding is performed at different positions of the roof rails to be molded; A die lifting step (step S1) in which the punch 30 is installed and the holder 40 for guiding the punch 30 is installed and the upper die 10 of the pad A and the pad C is lifted up; A panel holding step (S2 step) in which the flange portion of the pad B holds the panel; A stamping and padding step S3 of padding the pad A, the pad B and the pad C simultaneously with the stamping of the pad B; And the flange portion of the upper die 10 at the pad A and the pad C forms a molding step S4 of molding the side wall of the panel to correct the automobile body panel mold by the double cross pad mold structure, (

), A double cross pad mold structure which does not require a stepping process in the process of press molding a member of an automobile body panel and a car body panel such as a rail is developed, It is a useful invention with particular advantages that can eliminate the list-like process.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for a vehicle body panel mold having a double cross pad mold structure,

More particularly, the present invention relates to an apparatus and method for calibrating an automobile body panel mold, and more particularly, to a mold for drawing a mold of a general roof rail by dividing a mold die into dies and pads, dividing the molds of the molds into three equal parts, A device and method for correcting an automobile body panel mold by a double cross pad mold structure capable of functioning as a listike after a drawing molding with a structure in which only the upper surface except the flange portion is formed, .

In order to produce the automobile body panel (the roof rail) shown in Fig. 1 by press molding, there is a difference depending on the shape, but generally, as shown in Fig. 2, blanking, one or more drawing or forming, , Trimming, piercing, and restriking. At this time, in particular, in the case of involving a bending or flange process, the springback phenomenon due to the elastic restoration of the steel sheet is experienced, so that the formed panel shape deviates from the desired product shape.

As shown in Fig. 3, the drawing metal mold of a general roof rail holds a die of a lower mold holder and an upper mold die at a flange portion, and then a lower die punch mold is molded to produce a final product. When the length is longer than the width of the cross section like the roof rail and the curvature is also in the longitudinal direction, the torsion and the springback are larger at both ends than the central portion of the panel.

)으로 제품의 길이가 길어 길이 방향으로 비틀림 변형도 발생하므로 제품의 정밀도를 확보하기가 더욱 어렵다.Particularly, the members or rails in the body panel are hat-shaped basic cross-sections

), The length of the product is long, and distortion in the longitudinal direction is also generated, so that it is more difficult to secure the accuracy of the product.

Recently, the use of ultra high tensile strength steel with tensile strength of 700 MPa or more has been increasing. However, as the tensile strength of the material steel increases, the elongation is lowered and not only the formability is lowered, but also the longitudinal twist and springback deformation There are many difficulties to solve.

The springback is a typical molding defect that occurs during plate material molding by press with wrinkling and crack. The springback phenomenon refers to a change in shape due to resilient reshaping to maintain a static equilibrium state due to residual stress in the plate when external force is released by restraining the plate from being restrained by the die during plate material forming process. The springback will reduce the dimensional accuracy of the product and it must be solved because it causes quality deterioration, bad appearance between parts and poor assembly.

The springback is known to be influenced by various factors such as geometric parameters of the molded part, material parameters such as thickness and material properties of the part, blank holding force, punch speed, process parameters such as friction and lubrication. In case of process variable, it is often solved by experience, trial and error, and intuition. When the shape and material parameters are the main factors of springback, the shape and angle of deformation, yield strength, elastic modulus, material thickness, etc.

In the field of industry, experience or experience in trial-out of molds, try to determine the proper conditions for molding or modify the mold to correct the mold and correct the mold to reduce the amount of springback. In addition, a listike process is added to solve the problem in order to secure the shape dynamics. Especially, the increase of process leads to adverse effects such as development cost of new cars and increase of development time. Especially, high-strength steel sheet shows a molding characteristic such as occurrence of springback in piercing and trimming process which is not experienced in general steel sheet. Therefore, it is necessary to predict springback of high-strength steel sheet more accurately, Weight reduction can be realized.

The listike correction method is the most commonly applied method for designing the current press mold to remove springback. First, the steel sheet is blanked in the first step to form a blank, and the springback is controlled and reduced in the first forming step through the two forming steps (second and third steps), and at the same time, The spring back amount is estimated and corrected in advance by about 1 ° to 2 °. Finally, in the last step (the fourth step), the springback amount is finally corrected by the strike-off process from the side.

However, this method requires a total of four processes such as a foaming process and a restriking process in addition to the blanking process. As a result, the number of molds and production costs increase. In general, when the blank shape is a free-form surface, the inflow amount of the blank is not constant. Therefore, the method must repeatedly modify the shape of the initial blank in the first step through the result of the fourth step, which is the final step, and the blanking mold for the first step must also be repeatedly modified (i.e., )shall. Finally, based on the results of the fourth step, the mold must be revised to recalibrate the springback amount in the third step.

As a result, this method has drawbacks that it is difficult to obtain overall competitiveness due to an increase in mold development cost, an increase in mold development period, an increase in stamping airflow for panel molding in a car maker, and a decrease in precision of a panel.

Recently, in order to solve the problem of spring back, when the automobile body panel such as the U-shaped vehicle body panel is press-molded, the edge of the vertical wall flange is pushed upward by pressing the lower mold, And an upholstery method in which elastic deformation is suppressed by being brought into close contact has been introduced.

In addition, there is a mold correction method by draw bead as a second method which is commonly used in the present press mold design for removing the spring back. In order to increase the tensile stress on the blank to reduce the springback, an addendum is formed on the outer side of the product line (as shown in FIG. 4) and the drawbid is further processed to stretch the blank to be. In other words, the work process consists of a drawing process in one process, a trimming process in a blank along a trim line in two processes, a piercing process in three processes, a cutting and a cam cutting process, and finally, Is completed.

In this method, the initial blank size is increased by about 30% as the blank size is increased by the addition of the blank face, so that the blank material ratio is increased and the production cost of the draw die is increased. In addition, the amount of springback should be measured to correct the mold again. Finally, in the case of the cam mold, which is required for the four-step cam flanging, the difficulty of the mold modification and the correction time are more than twice as much as the correction of the general mold, so the production cost and the modification cost of the mold rapidly increase, .

In the case of a member or a rail panel, first, after deformation is predicted to solve the springback in the longitudinal direction, the inverse correction technique considering the predicted deformation of the whole shape in the longitudinal direction is applied to the mold, And a correction procedure such as deforming the inclination of the flange of the sidewall is applied. However, when a panel is manufactured by drawing or forming a very high-tension material, it is common to add a list-like process after trimming or piercing. Therefore, by applying the double cross pad mold structure as in the present invention, it is possible to eliminate the list-like process by grasping the dimensional deformation during the drawing or forming forming process.

In this way, the basic cross-section of a member or a rail of an automobile body panel is hat-shaped, and is mostly long. When a member or a rail is formed, a torsional deformation occurs due to a long length, and a springback deformation occurs at a side wall of the basic section. At both ends of the product, the springback is more severely generated with a torsional deformation.

In order to control this deformation, the upper die of the mold is divided into three equal parts, and the central part having less deformation is formed as a whole product, and a pad for holding the upper part of the hat- It is made of a double cross-pad mold which is divided into a die for forming a flange. The flange portion of the pad B first holds the panel in a state in which the pad A and the pad C portion of FIG. 5 are lifted and then the flange portion of the pad B is stamped At the same time, padding of the pad (A), the pad (B) and the pad (C) is performed. Finally, when the flange portions of the upper die of the pad (A) and the pad (C) form the side wall of the panel, torsion on the springback occurring at the pad (A) The deformation can be more effectively controlled.

The double cross pad mold structure can generally be applied to the first process. In the case of ultra-high tensile steel sheet, which is widely applied for light weight automobile recently, it is possible to remove the restrike process when applied to a drawing process It is possible to determine the press forming process and the process in a reasonable manner, and the economic effect such as the increase of the productivity due to the process deletion can be increased.

)으로 길이가 긴 자동차 차체 패널의 멤버 및 레일류와 같은 형태의 자동차 차체 패널을 프레스 성형하는 과정에서 리스트라이킹 공정이 필요 없는 더블 크로스 패드 금형 구조에 의한 자동차 차체 패널 금형 보정 장치 및 방법을 제공함에 있다.The present invention was made to solve the various drawbacks and problems caused by the drawing mold structure of a conventional roof rail, and it is an object of the present invention to provide a mold for a vehicle body panel by a double cross pad mold structure,

The present invention provides an apparatus and a method for correcting an automobile body panel mold by a double cross pad mold structure that does not require a stepping process in the process of press molding a member of an automobile body panel having a long length such as a railway car body panel have.

In order to achieve the above object, the present invention provides an apparatus for correcting an automobile body panel mold by a double cross pad mold structure, comprising: an upper die; A blank 20 provided at the bottom of the upper die 10; A plurality of punches 30 disposed at the bottom of the blank 20 and positioned at lower portions thereof and having height differences such that molding is performed at different positions of the roof rails to be molded; The punch 30 is installed and guided by the holder 40 so that the flange portion of the upper die 10 at the pad A and the pad C forms the side wall of the panel .

)으로 길이가 긴 자동차 차체 패널의 멤버 및 레일류와 같은 형태의 자동차 차체 패널을 프레스 성형하는 과정에서 리스트라이킹 공정이 필요 없는 더블 크로스 패드 금형 구조를 개발함으로써 플랜지 부위에 발생하는 스프링백에 대한 독립적인 제어가 가능하므로 제품의 양 끝단에서 크게 발생하는 비틀림 및 스프링백 변형을 보다 효율적으로 제어할 수 있을 뿐만 아니라 금형의 측벽의 모서리 반지름이나 기울기를 자유롭게 역 보정하여 성형할 수 있으므로 루프 레일 양 끝단에서의 비틀림 변형이나 스프링백 변형을 보정할 수 있고, 드로잉 또는 포밍과정에서 치수 변형을 잡으면, 리스트라이크 공정을 삭제할 수 있는 각별한 장점이 있다.The present invention relates to a mold for a vehicle body panel mold by a double cross pad mold structure,

), A double cross-pad mold structure which does not require a stepping-back process in the process of press-molding an automobile body panel such as a member of a long-length automobile body panel and a rail-like automobile body, It is possible to more effectively control the torsion and springback deformation that occur at both ends of the product, as well as to mold the corner radius or tilt of the side wall of the mold by freely reversing it. It is possible to correct the torsional deformation and the spring back deformation of the torsion bar, and there is a special advantage that the torsional deformation can be eliminated if the dimensional deformation is caught during the drawing or forming process.

1 is a view showing an automobile body panel (roof rail)
Figure 2 shows a vehicle body panel press forming standard four process layout,
3 is a drawing mold structure of a conventional loop rail,
4 is a diagram showing a trimming process and cam flanging, which are two processes of a droudbee correction method,
5 is a view showing the basic structure of the entire double cross pad according to the present invention,
FIGS. 6A to 6D are process charts illustrating a method of correcting an automobile body panel mold by a double cross-pad mold structure according to the present invention;
FIG. 7 is a flowchart showing a method of correcting an automobile body panel mold by the double cross pad mold structure of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of an apparatus and method for correcting an automobile body panel mold by a double cross pad mold structure according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 5 is a view showing a basic structure of an entire double cross pad according to the present invention. FIGS. 6A to 6D are views showing a method of correcting an automobile body panel mold by a double cross pad mold structure according to the present invention. An automobile body panel mold correcting apparatus according to the present invention has an upper die (10), a lower die (10), and an upper die (10). A blank 20 provided at the bottom of the upper die 10; A plurality of punches 30 disposed at the bottom of the blank 20 and positioned at lower portions thereof and having height differences such that molding is performed at different positions of the roof rails to be molded; The punch 30 is installed and guided by the holder 40 so that the flange portion of the upper die 10 at the pad A and the pad C forms the side wall of the panel.

The method for correcting an automobile body panel mold by the double cross pad mold structure according to the present invention includes a die lifting step (step S1) in which the upper die 10 of the pad A and the pad C are lifted up; A panel holding step (S2 step) in which the flange portion of the pad B holds the panel; A stamping and padding step S3 of padding the pad A, the pad B and the pad C simultaneously with the stamping of the pad B; And the flange portion of the upper die 10 at the pad A and the pad C forms a sidewall of the panel (S4 step).

The structure can be controlled independently by separating both ends of the panel from the center of the panel, and the radius or tilt of the corner of the side wall of the mold can be freely and inversely corrected to form a listike function after drawing.

Example

The automobile body panel mold by the double cross pad mold structure of the present invention shown in Figs. 6 and 7 was corrected.

The upper die 10 of the region where the pad A and the pad C are provided is raised (Fig. 6A) in the die lifting step (S1 step) shown in Fig. 7 and then the pad The flange portion grips the panel (Fig. 6B) and pads the pad A, the pad B and the pad C simultaneously with the stamping of the pad B in the stamping and padding step (S3 step) (Fig. 6C). Finally, the flange portion of the upper die 10 at the pad A and the pad C portions in the molding step S4 step forms the side wall of the panel (Fig. 6D).

By doing so, the pad A and the pad C can be formed by performing the operation of the upper mold different from the pad B, and by forming the corner radius or tilt of the side wall of the mold by freely reversely correcting it, It was confirmed that the torsional deformation and the springback deformation can be easily corrected.

While the present invention has been described with reference to the preferred embodiments, it is to be understood that the present invention is not limited thereto and various changes and modifications may be made without departing from the scope of the invention.

10: upper die 20: blank
30: Punch 40: Holder

Claims (4)

An upper die 10; A blank 20 provided at the bottom of the upper die 10; A plurality of punches 30 disposed at the bottom of the blank 20 and positioned at lower portions thereof and having height differences such that molding is performed at different positions of the roof rails to be molded; And a flange portion of the upper die (10) at a pad (A) and a pad (C) portion is formed by a holder (40) for guiding the punch (30) 1. A vehicle body panel mold correcting apparatus comprising:
A double cross function can be simultaneously performed after drawing molding by freely inversely correcting the radius or tilt of the corner of the side wall of the mold by independently controlling both ends of the panel from the center of the panel. Automobile body panel mold compensation device by pad mold structure. delete A die lifting step (S1 step) in which the upper die 10 of the region where the pad (A) and the pad (C) are lifted up; A panel holding step (S2 step) in which the flange portion of the pad B holds the panel; A stamping and padding step S3 of padding the pad A, the pad B and the pad C simultaneously with the stamping of the pad B; Wherein the flange portion of the upper die (10) at the pad (A) and the pad (C) forms a side wall of the panel (S4 step) A method comprising:
A double cross function can be simultaneously performed after drawing molding by freely inversely correcting the radius or tilt of the corner of the side wall of the mold by independently controlling both ends of the panel from the center of the panel. Calibration method of automobile body panel mold by pad mold structure. delete

Images