Patent Publication Number: US-2016221053-A1

Title: Dieless sheet forming apparatus with flexible rollers

Description:
TECHNICAL FIELD 
     The present invention relates to a dieless sheet forming device, and more particularly, to a dieless sheet forming device that is provided with flexible forming rollers whose curvatures are adjustable, thus being adequate for small quantity batch production. 
     BACKGROUND ART 
     So as to form a thick or thin sheet, generally, upper and lower dies  1  corresponding to a desired forming shape of a sheet  3  are made, as shown in  FIG. 1 , and after the sheet  3  is disposed between the upper and lower dies  1 , it is formed by means of a press. 
     In this case, the conventional sheet forming device using the dies can produce sheets having the same curved shapes as each other in large quantities, but if a desired forming shape is corrected or changed, new dies should be made, so that the die designing cost and the production cost of the final product are all increased, thus being not adequate for small quantity batch production. Besides, even though the desired forming shape is not corrected, additional costs for keeping, maintaining and discarding the dies are needed when the dies are being not used temporarily or permanently. 
     So as to solve the above-mentioned problems, accordingly, there has been proposed Korean Patent Registration No. 10-1034592 wherein a multi-point sheet forming device includes an upper die  11   a  and a lower die  11   b  each having a plurality of punches movable up and down independently of each other, as shown in  FIG. 2 . The conventional multi-point sheet forming device adjusts the heights of the punches formed on the upper die  11   a  and the lower die  11   b  if a desired forming shape is corrected or changed, thus easily changing the forming shape. However, irregular spaces are formed between the sheet and the forming device due to the radius of curvature of each punch head and the height difference between the punches, which makes it hard to form the curved surface having locally small radius of curvature or edge, and further, since the edges of the sheet are not formed well, they cut to cause the sheet material to be unnecessarily consumed. Moreover, if it is desired to form a thin sheet, not a thick sheet, dimples or local wrinkles occur in accordance with the sizes of the punches. 
     So as to solve the above-mentioned problems, accordingly, elastic pads  25  made of for example an urethane material are disposed between forming punches  21   a  and  21   b  and a sheet  23 , respectively, as shown in  FIG. 3 , but the lengths of the punches should be readjusted in accordance with the materials of the elastic pads  25  and desired forming shapes of the sheet  23 , which also decreases the operating efficiency of the device and the forming precision of the sheet. 
     Further, the conventional die forming device and the conventional multi-point forming device using the plurality of punches are restricted in the size of the final forming shape in accordance with the sizes of the dies, and so as to form a large-sized sheet, therefore, the final forming shape is sectionalized and formed. Next, the sectionalized forming shapes are bonded through additional mechanical process and welding to produce the final product, and otherwise, heat is directly applied to the sheet to form the curved surface of the sheet by using residual stress generated by the heat. However, such additional processes increase the forming cost and period of the sheet. 
     DISCLOSURE 
     Technical Problem 
     Accordingly, the present invention has been made in view of the above-mentioned problems occurring in the prior art, and it is an object of the present invention to provide a dieless sheet forming device that is simple in configuration to allow a forming shape to be easily corrected even if a desired forming shape is changed, while dimples or wrinkles are being not formed on the formed sheet, thus being adequate for small quantity batch production. 
     It is another object of the present invention to provide a dieless sheet forming device that can form even the edge portions of a sheet, without having the limitation on the thickness or size of the sheet. 
     Technical Solution 
     To accomplish the above-mentioned objects, the present invention proposed a dieless sheet forming device including: two forming rollers rotatably disposed up and down to correspond with each other and bent to various curvatures; and a plurality of roller adjustment members whose one ends are fixed to each forming roller in such a manner as to be adjusted in length to adjust the curvatures of the forming rollers and the distances between the two forming rollers, wherein the curvatures of the forming rollers and the distances between the forming rollers through which a sheet to be formed is passed are adjusted by means of the roller adjustment members to change the forming shape of the sheet. 
     According to the present invention, that is, the sheet is formed between the two forming rollers disposed up and down, which makes the configuration of the device simple and allows the sheet to be formed without having any limitation on the lengthwise size thereof. Further, the curvatures of the forming rollers and the distance between the forming rollers are adjusted by means of the roller adjustment members, which make the forming shape easily corrected, so that the device of the invention is adequate for small quantity batch production. 
     In accordance with a preferred embodiment, each roller adjustment member includes an external member having an internal screw thread and an internal member having an external screw thread and is adjusted in length in accordance with the screw-coupled length between the external member and the internal member. 
     According to the present invention, like this, the curvatures of the forming rollers are differently adjusted by means of the length adjustment of the roller adjustment members, which produces sheets having a single curvature, a double curvature, a multi curvature, a twisted shape and the like. 
     In accordance with a preferred embodiment, the external member is fixed to one of two forming rollers, and the internal member is connected to the motor, so that the length of each roller adjustment member can be adjusted through the rotation of the motor. Each roller adjustment member may be connected to a separate motor, and otherwise, the plurality of roller adjustment members may be adjusted in lengths through the movement of a single motor or a plurality of motors. Like this, the lengths of the roller adjustment members can be easily adjusted through the motors. 
     In accordance with a preferred embodiment, the end of the external member fixed to one of two forming rollers is rotatably provided with a roller guide, which has a recess having a shape of major arc (an arc bigger than a semicircle), into which the forming roller is fittedly inserted. That is, while each forming roller is being fittedly mounted into the rotatable recesses of the roller guides thereof, the roller adjustment members are adjusted in lengths to easily change the various curvatures of the forming roller. 
     According to the present invention, the sheet to be formed is inserted between the two forming rollers and pulled so as to be passed through between the forming rollers, thus completing the forming operation of the sheet. One of the forming rollers may be connected and rotated at both ends thereof to roller rotation motors, and otherwise, both of the forming rollers may be drove by the roller rotation motors. In this case, the sheet engaged with the forming rollers is pushed and formed through the rotation of the roller rotation motors. 
     Each forming roller is made of steel having high modulus of elasticity. Solid bar-type rollers can be treated through heat treatment allowing an adequate elastic behavior during forming procedure. Alternatively, each forming roller is wound by a plurality of steel wires, and at this time, desirably, the steel wire wound on the outer peripheral surface of each forming roller becomes flat on an outside surface contacted with the sheet, through grinding. Otherwise, the steel wire wound on the outer peripheral surface of each forming roller has an oval section to allow the outside surface contacted with the sheet to be flat. Like this, the sheet is formed along the continuously curved surfaces of the forming rollers having flat outer peripheral surfaces, thus providing the sheet having a smooth formed surface on which no local dimples or wrinkles exist. 
     Advantageous Effects 
     The dieless sheet forming device according to the present invention can adjust the shapes of the upper and lower forming rollers and the distance between them to form a sheet, and can be accordingly simple in configuration and relatively small in installation area, thus greatly reducing the die production cost, the die storing cost and the die maintenance cost. 
     The curvatures of the forming rollers and the distances between them can be adjusted by means of the roller adjustment members, thus performing various changes in the forming shapes, so that the device can be adequate for small quantity batch production and can form a large-sized sheet, without having any limitation on the length of the sheet, thus needing no additional mechanical process. 
     The sheet can be formed along the continuous curved surfaces of the forming rollers, without having any punches, so that even the edges of the sheet can be formed and no dimples or wrinkles is formed even on a thin sheet. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic view showing one conventional die sheet forming device. 
         FIG. 2  is a schematic view showing another conventional multi-point sheet forming device. 
         FIG. 3  is a schematic view showing still another conventional multi-point sheet forming device having elastic pads. 
         FIG. 4  is a schematic perspective view showing a dieless sheet forming device according to the present invention. 
         FIG. 5  is a perspective view showing a roller adjustment member used in the dieless sheet forming device according to the present invention. 
         FIG. 6  is a partial sectional view showing an example of the roller adjustment member of  FIG. 5  coupled to a motor. 
         FIG. 7  is a sectional view showing another example of the roller adjustment member of  FIG. 5  coupled to a motor. 
         FIG. 8  is a side view showing one example of a forming roller used in the dieless sheet forming device according to the present invention. 
         FIG. 9  is a side view showing another example of a forming roller used in the dieless sheet forming device according to the present invention. 
         FIG. 10  is a schematic perspective view showing one example of the sheet forming between two forming rollers. 
         FIG. 11  is a schematic perspective view showing another example of the sheet forming between two forming rollers. 
         FIG. 12  is a sectional view showing the arrangement of the upper and lower forming rollers when a convex type sheet is formed through the dieless sheet forming device according to the present invention. 
         FIG. 13  is a perspective view showing the forming shape of the sheet through the arrangement of the upper and lower forming rollers of  FIG. 12 . 
         FIG. 14  is a sectional view showing the arrangement of the upper and lower forming rollers when a saddle type sheet is formed through the dieless sheet forming device according to the present invention. 
         FIG. 15  is a perspective view showing the forming shape of the sheet through the arrangement of the upper and lower forming rollers of  FIG. 14 . 
         FIG. 16  is a sectional view showing the arrangement of the upper and lower forming rollers when a twisted type sheet is formed through the dieless sheet forming device according to the present invention. 
         FIG. 17  is a perspective view showing the forming shape of the sheet through the arrangement of the upper and lower forming rollers of  FIG. 16 . 
     
    
    
     MODE FOR INVENTION 
     Hereinafter, an explanation on a dieless sheet forming device according to a preferred embodiment of the present invention will be in detail given with reference to the attached drawings. 
       FIG. 4  is a schematic perspective view showing a dieless sheet forming device according to the present invention. As shown, a dieless sheet forming device  100  according to the present invention has two forming rollers  101   a  and  101   b  horizontally disposed up and down to correspond with each other. The forming rollers  101   a  and  101   b  can be flexibly bent to various curvatures, respectively. 
     Each of the forming rollers  101   a  and  101   b  is equipped with a plurality of roller adjustment members  103  so as to adjust the curvature.  FIG. 5  shows an example of the roller adjustment member  103 , and  FIG. 6  is a partial sectional view showing the roller adjustment member  103  in detail. The roller adjustment member  103  includes an external member  105  having an internal screw thread and an internal member  107  having an external screw thread. The internal member  107  is fittedly screw-coupled to the external member  105 , and the roller adjustment member  103  is adjusted in length in accordance with the screw-coupled length between the external member  105  and the internal member  107 . 
     So as to easily adjust the length of the roller adjustment member  103 , as shown in  FIG. 6 , the roller adjustment member  103  is connected to a motor. That is, the external member  105  is fixed to the forming roller, and the internal member  107  is connected to the motor, so that as the coupled depths of the internal member  107  to the external member  105  are varied through the rotation of the motor, the whole length of the roller adjustment member  103  can be adjusted. A separate motor may be connected to each roller adjustment member  103 , but as shown in  FIG. 7 , the plurality of roller adjustment members  103  may be adjusted in lengths through the movement of a single motor or a plurality of motors. 
     The respective internal members  107  are rotated by means of the single motor or the plurality of motors, thus adjusting the lengths of the roller adjustment members  103 , and accordingly, the shape of the forming roller connected to one ends of the external members  105  and the distance between the upper and lower forming rollers  101   a  and  101   b  can be adjusted. 
     Returning to  FIGS. 5 and 6 , the roller adjustment member  103  has a roller guide  109  disposed rotatably at the end thereof fixed to the forming roller  101   a  or  101   b , that is, at the bottom end of the external member  105 . The roller guide  109  has a recess  109   a  having a shape of major arc, into which the forming roller  101   a  or  101   b  is fittedly inserted. As the plurality of roller adjustment members  103  is vertically arranged with respect to the horizontally arranged two forming rollers  101   a  and  101   b , the rotatable roller guides  109  to which the forming rollers  101   a  and  101   b  are fitted are adapted to allow the forming rollers  101   a  and  101   b  to be naturally bent when the curvatures of the forming rollers  101   a  and  101   b  are adjusted through the length adjustment of the roller adjustment members  103 . 
       FIGS. 8 and 9  show examples of the forming roller. As shown, the forming roller  101   a  is wound by a plurality of steel wires to a plurality of layers. The steel wire wound on the outermost peripheral surface of the forming roller  101   a  is desirably flat, on an outside surface  111  contacted with a sheet, through grinding. As the outside surface  111  of the forming roller  101   a  contacted with the sheet is flat, occurrences of local dimples or wrinkling can be prevented. Alternatively, the steel wire wound on the outermost peripheral surface of the forming roller  101   a  has an oval section to allow the outside surface  111  contacted with the sheet to be flat. In the drawings, one forming roller  101   a  has been described, but the other forming roller  101   b  has the same configuration as the forming roller  101   a.    
     Further, as shown in  FIG. 4 , the forming rollers  101   a  and  101   b  may be connected at both ends thereof to roller rotation motors  113 , thus being automatically rotated. In this case, as shown in  FIG. 10 , the sheet  102  is fittedly disposed between the forming rollers  101   a  and  101   b  and thus pushed and formed through the rotation of the forming rollers  101   a  and  101   b . At this time, the forming shapes of the sheet  102  are determined upon the shapes of the forming rollers  101   a  and  101   b  and the distance between them, and as mentioned above, the shapes of the forming rollers  101   a  and  101   b  and the distance between them are adjusted by means of the roller adjustment members  103  in accordance with desired forming shapes of the sheet  102 . Alternatively, the roller rotation motors  113  may be connected to any one of the forming rollers  101   a  and  101   b , thus transmitting the driving force, and otherwise, no roller rotation motors  113  may be provided. In case of the non-existence of the roller rotation motors  113 , as shown in  FIG. 11 , the sheet  102  is inserted between the forming rollers  101   a  and  101   b  and pulled and formed from the opposite side to the inserted portion. In the same manner as above, the forming shapes of the sheet  102  are determined upon the shapes of the forming rollers  101   a  and  101   b  and the distance between them, and the shapes of the forming rollers  101   a  and  101   b  and the distance between them are adjusted by means of the roller adjustment members  103 . 
     Like this, since the sheet  102  is formed through the adjustment of the shapes of the forming rollers  101   a  and  101   b  and the distance between them, the forming shapes of the sheet  102  can be simply corrected in accordance with the changes of the desired forming shapes of the sheet  102 . Further, the forming rollers  101   a  and  101   b  providing the continuous forming surfaces are rotated while interposing the sheet  102  therebetween, thus forming the sheet  102 , so that no dimples or wrinkles exist. 
     Hereinafter, examples of forming the sheet through the dieless sheet forming device according to the present invention will be in detail explained. 
     In the dieless sheet forming device  100  according to the present invention, the forming shapes of the sheet  102  are determined upon the curvatures of the two forming rollers  101   a  and  101   b  corresponding up and down with each other and the distance between them. That is, a length of the formed sheet  102  becomes longer as the gap between the forming rollers  101   a  and  101   b  is narrower, and contrarily, a length of the formed sheet  102  is shorter as the gap between the forming rollers  101   a  and  101   b  is wider. Under the above principle, the curved surface of the sheet  102  is formed. 
     For example, as shown in  FIG. 12 , if the gap between the forming rollers  101   a  and  101   b  is narrow in the middle portion c of the forming rollers  101   a  and  101  and wide in the edge portions a and e thereof to provide a distance (a=e)&gt;(b=d)&gt;c, a length of the formed sheet  102  becomes long in the middle portion c′ of the formed sheet  102  and short in the edge portions a′ and e′ thereof, as shown in  FIG. 13 , thus providing a length c′&gt;(b′=d′)&gt;(a′=e′) and accordingly forming the convex type sheet  102 . 
     Further, as shown in  FIG. 14 , if the gap between the forming rollers  101   a  and  101   b  is wide in the middle portion c of the forming rollers  101   a  and  101  and narrow in the edge portions a and e thereof to provide a distance c&gt;(b=d)&gt;(a=e), a length of the formed sheet  102  becomes short in the middle portion c′ of the formed sheet  102  and long in the edge portions a′ and e′ thereof, as shown in  FIG. 15 , thus providing a length (a′=e′)&gt;(b′=d′)&gt;c′ and accordingly forming the saddle type sheet  102 . 
     Furthermore, as shown in  FIG. 16 , if the gap between the forming rollers  101   a  and  101   b  is gradually wider in one direction thereof to provide a distance e&gt;d&gt;c&gt;b&gt;a, a length of the formed sheet  102  becomes gradually longer in the order of a′&gt;b′&gt;c′&gt;d′&gt;e′, thus forming the twisted type sheet  102 . 
     The curvatures and distances of the forming rollers  101   a  and  101  are adjusted to various sheets by means of the length adjustment of the roller adjustment members  103 , and accordingly, the sheet  102  can be formed to various shapes. Therefore, the sheet forming device according to the present invention can be applied for small quantity batch production, can form even the edge portions of the sheet, and can form the sheet without having the limitation on the length of the sheet. 
     While the present invention has been described with reference to the particular illustrative embodiments, it is not to be restricted by the embodiments but only by the appended claims. It is to be appreciated that those skilled in the art can change or modify the embodiments without departing from the scope and spirit of the present invention.