The present disclosure relates to a roll stamping apparatus including a rotating roll having a molding portion by which a stamped structure is applied to an outer surface.
In general, numerous sheet metal molding technologies have been developed to produce parts applied to an automobile, or the like.
First, a stamping method is most widely used, and such a stamping method includes an upper die, a lower punch disposed below the upper die, and a material holder disposed between the upper die and the lower punch. Here, the upper die is a mold member having a groove portion formed in a lower surface thereof, wherein the groove portion is fitted to a shape of an article to be molded, and the lower punch is a member disposed below the upper die and is driven upwardly to thereby upwardly push a material moving between the upper die and the lower punch to press the material onto the upper die.
Such a stamping method is a technology which is widely used to produce the molded articles, for example, parts of the automobile, but in recent years, there are a problem in which capacity of the apparatus should be increased in an application of high-strength steel, and a problem in that the material is broken due to vulnerable moldability of the high strength steel.
Next, a roll forming (RF) method is used. The roll forming method is configured so that a set of multistage fixed upper and lower rotating rolls is arranged and a coil or a cut material passes therebetween, and molds a molded article, a part having a long length while having a constant cross-section shape.
The roll forming method by the rolling forming apparatus as described above may be applied to the high strength steel by utilizing an apparatus having relatively small capacity, but has a limitation in that only a molded article having the constant cross-section shape may be produced.
Accordingly, a roll stamping method as disclosed in Patent Document 1 has been developed. In the roll stamping method, since a stamped structure is applied to a rotating roll which is rotated, the roll stamping method is a method of performing variable cross section roll forming while the material passes through the rotating roll.
However, in the roll stamping method as described above, there is a problem in that an undesirable shape, such as a distortion or the like, due to residual stress of a cross section changing portion and unbalance of force between the respective cross section changing portions within a part, may occur.
(Patent Document 1) KR1417278 B
An aspect of the present disclosure is to provide a roll stamping apparatus and method that do not have an undesirable shape by solving residual stress of a cross section changing portion and unbalance of force between the cross section changing portions.
The present disclosure provides a roll stamping method and apparatus to achieve the above-mentioned object.
According to an aspect of the present disclosure, a roll stamping apparatus includes sets of rollers rotating while facing each other so as to press opposite surfaces of a material which is continuously supplied to move between the rollers; and molding portions having a stamping structure applied to outer surfaces of the sets of rollers so as to mold the material, wherein a plurality of sets of rollers are disposed in a movement direction of the material, the respective molding portions of the sets of rollers are formed to sequentially change a cross section of the material in the movement direction of the material, and the molding portion of at least one set of rollers of the sets of rollers before a final set of rollers through which the material finally passes is a set of over-molding rollers having a length in a circumferential direction longer than the molding portions of the final set of rollers.
The set of over-molding rollers may be disposed within at least three sets of rollers of the final set of rollers.
The molding portion may include an intaglio formed in an outer surface of a rotation roll of one roller of the set of rollers and having both sides opened, and an embossment formed in an outer surface of a rotation roll of the other roller thereof and corresponding to the intaglio.
The molding portions of the sets of rollers may perform planarization for a cross section of the material by sequentially forming a concave-convex portion on the cross section of the material or removing the concave-convex portion from the cross section of the material in the movement direction of the material.
The molding portions of the sets of rollers may perform planarization for a cross section of the material by sequentially removing a concave-convex portion from the cross section of the material, the molding portions of the final set of rollers and the set of over-molding rollers may include flat portions which are flat in a width direction and have a predetermined length in a circumferential direction, and transition portions positioned at both sides of the flat portion in the circumferential direction, and a length of the flat portion of the set of over-molding rollers in the circumferential direction may be longer than a length of the flat portion of the final set of rollers in the circumferential direction.
Escape portions through which the material passes may be formed in the positions different from the molding portions in the outer surfaces of the sets of rollers.
The escape portions may be formed in opposite sides of the molding portions and may be concave in an inner diameter direction from outer circumferential surfaces of the rollers.
As set forth above, according to an exemplary embodiment in the present disclosure, the roll stamping apparatus and method may reduce the undesirable shape by solving the residual stress of the cross section changing portion and the unbalance of force between the cross section changing portions.
Hereinafter, exemplary embodiments in the present disclosure will be described with reference to the accompanying drawings.
Each of the roller sets 10, 20, 30, and 40 includes the molding portion, and sequentially changes the molding portion along the movement direction of the material as illustrated in
The product molded by the roll stamping apparatus described above may include transition portions T1 and T2 which are changed to portions (cross sections A-A and C-C) having a first shape and a portion (a cross section B-B) molded by the molding portion and having a second shape. The above-mentioned transition portions T1 and T2 may have residual stress that exists in directions opposite to each other, and have a problem in that the transition portions are distorted when being cut into the product or before being cut into the product.
An object of the present disclosure is to reduce the undesirable shape of the product by removing the residual stress remaining in the transition portions or at least preventing the transition portions from being distorted, and
As illustrated in
As illustrated in
Here, the shape of the material or the number of the sets of rollers is merely an example, the number of the sets of rollers may be increased or decreased as needed, and the material may have a shape corresponding to a desired product. In addition, although
Accordingly, since the transition portions 102 and 103 and the return portions 105 and 106 of the material are molded from the first shape to the second shape and are thus molded in a reverse direction of a direction of the formed residual stress, the residual stress of the final product may be reduced.
In
In addition, the set of over-molding rollers 50 may include a case in which the length in the length direction of the material, that is, the length in the circumferential direction of the roll is longer than the lengths of the molding portions of the final set of rollers in the circumferential direction, and may also include a case in which since a degree of the material molded by the set of over-molding rollers is greater than that molded by the molding portions of the final set of rollers, the material is changed in a reverse direction to become the second shape, the target shape (the material does not change from the first shape to the second shape but changes to a third shape that is a shape beyond the second shape and then to the second shape) again.
The roll stamping apparatus according to the present disclosure may also be applied to a roll stamping method corresponding thereto. Since the distortion of the material becomes more problematic when the material is cut, the roll stamping method according to the present disclosure may include a plurality of molding steps of molding a material which is continuously supplied, through stamping structures formed on outer surfaces of the sets of rollers 10, 20, 40, and 50, and a cutting step of cutting the molded material, wherein the material passes through the plurality of molding steps such that a portion thereof is changed from a first shape to a second shape, and the plurality of molding steps include a reverse deformation molding step (the material passes through the set of over-molding rollers 50 and then passes through the final set of rollers 40), which is opposite to a deformed direction in which the material is deformed from the first shape to the second shape.
In this case, if the material is again molded in the molding direction in which the material is molded from the first shape to the second shape after the reverse deformation molding step, since the residual stress is increased in the directions opposite to each other in the transition portions 102 and 103 as in the related art and the distortion of the material may occur, the reverse deformation molding step may be performed at least after the middle of an entire molding step so that the molding in which the residual stress is again increased after the reverse deformation molding is small.
In addition, the residual stress of the transition portions 102 and 103 may also be reduced by increasing or decreasing the length of the molding portion, but the residual stress may also be reduced by changing the shape of the molding portion. For example, the residual stress of the transition portions 102 and 103 may also be reduced by performing a reverse direction bending in the transition portions 102 and 103 in the final molding step.
In both
In
In
The set of over-molding rollers may mold the material in a way in which an entire length of the molded region is increased by increasing the lengths of the transition portions 102 and 103 without changing the shape of the flat portion 101, and the over-molded material as described above may be returned to a target molding length L4 in the final set of rollers 40 and some of the transition portions 102 and 103 may become the return portions 105 and 106 (see
The roll stamping apparatus according to another exemplary embodiment illustrated in
According to the present exemplary embodiment, the escape portions 15a, 15b, 25a, 25b, 45a, 45b, 55a, and 55b are configurations formed to be concave inwardly from a circumference of the rolls, and are formed on the opposite sides of the molding portions 11a, 11b, 41a, 41b, 51a, and 51b.
As illustrated in
According to the present exemplary embodiment, since the sets of rollers 10, 20, 40, and 50 have the escape portions 15a, 15b, 25a, 25b, 45a, 45b, 55a, and 55b formed together with the molding portions 11a, 11b, 41a, 41b, 51a, and 51b, the sets of rollers 10, 20, 40, and 50 may mold the material S in the predetermined sections and bypass the material S in the predetermined section.
In particular, since the sets of rollers 10, 20, 40, and 50 are not in contact with the material S when the escape portions 15a, 15b, 25a, 25b, 45a, 45b, 55a, and 55b face each other, the material S may be moved faster than when the material S is molded. Therefore, the material may be molded without changing the sets of rollers even in a case in which an interval between molded sections L4 and L6 (see
Accordingly, a product in which a length of a roll forming portion according to the present exemplary embodiment is diverse may also be manufactured. In particular, in the case of a configuration such as a door impact beam in which the molded section is constant and a length thereof is diverse, one roll stamping apparatus may mold door impact beams having various different lengths.
Hereinabove, although the exemplary embodiments in the present disclosure have been described, the present disclosure is not limited thereto and may be variously changed and used.
Number | Date | Country | Kind |
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10-2015-0185116 | Dec 2015 | KR | national |
This application is a Divisional Patent Application of U.S. patent application Ser. No. 16/065,748, filed on Jun. 22, 2018, which is a U.S. National Phase under 35 U.S.C. § 371 of International Patent Application No. PCT/KR2016/015055, filed on Dec. 21, 2016, which claims priority to and the benefit of Korean Application No. 10-2015-0185116, filed on Dec. 23, 2015, the entire contents of which are incorporated herein by reference.
Number | Date | Country | |
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Parent | 16065748 | Jun 2018 | US |
Child | 17752459 | US |