Patent Publication Number: US-2017361368-A1

Title: Stamped and welded process for making steel rectangular or square tubular parts and parts therefrom

Description:
This application claims the benefit from U.S. Provisional Application Ser. No. 62/351121 filed Jun. 16, 2016. 
    
    
     BACKGROUND OF THE INVENTION 
     Conventional methods for making steel pipes that become approximately square steel tube pass a preformed cylindrical tube through a series of a plurality of forming rolls (rolling mills) to gradually form a square shape steel pipe. Various considerations are taken into account with respect to the corners and weld hardness of the base material. The hardness value, therefore, it will lead to the yield strength of the corner portion and the weld portion becomes large, ductility becomes low, and during the second welding there is a danger of cracks. It takes special management, and because the mechanical properties uneven residual stress is generated, it is also difficult to carry out cutting work. The conventional method of forming steel square or rectangular shaped tubular parts and products require pre and post operations for adding additional shapes and holes. Only specific sizes and shapes can be purchased typically. 
     Accuracy and tolerances of features, holes and trim lines need to be greater with the current processes. Only specific sizes and shapes are typically readily available. 
     There remains a need to improve steel square or rectangular shaped tubular parts and the method of making the same. This instant invention solves the prior problems in the art. 
     SUMMARY OF INVENTION 
     An object of the present invention is to provide a method for producing a steel square or rectangular pipe with an improved process. 
     Another object of the present invention is to provide a method for producing a steel square or rectangular pipe which minimizes stress and distortion on steel material and enables forming a more accurate product. 
     Yet another object is to provide an improved a steel square or rectangular pipe. 
     Still another object to provide a less expensive steel square or rectangular pipe with ease of sizing and shaping. 
     Accordingly, one aspect of the invention is directed to a method of making steel square or rectangular pipe. In the case of forming a square pipe, the method includes the steps of providing a generally planar steel plate having a predetermined thickness, a front surface and a back surface, a first longitudinal edge and a second longitudinal edge, and a first transverse edge and a second transverse edge, scoring a plurality of lines longitudinally across the back surface, wherein a first longitudinal score line is a first predetermined length X from the first longitudinal edge defining a first longitudinal section, a second longitudinal score line adjacent the first longitudinal score line is the predetermined length X therefrom defining a second longitudinal section, a third longitudinal score line adjacent the second longitudinal score line is the predetermined length X therefrom defining a third longitudinal section, and also is the predetermined length X from the second longitudinal edge defining a fourth longitudinal section. The method includes applying sufficient forces on the first longitudinal section and the second longitudinal section in a manner to form approximately 90 degree bend at the first longitudinal score line and applying sufficient forces on the fourth longitudinal section and the third longitudinal section in a manner to form approximately 90 degree bend at the third longitudinal score line, applying sufficient forces on the second longitudinal section and the third longitudinal section in a manner to form approximately 90 degree bend at the second longitudinal score line thereby causing the first and second longitudinal edges to abut. The method further includes applying a weld on the the first and second longitudinal edges to form a square steel pipe. 
     In the case of forming rectangular steel tube, the method includes the steps of providing a generally planar steel plate having a predetermined thickness, a front surface and a back surface, a first longitudinal edge and a second longitudinal edge, and a first transverse edge and a second transverse edge, scoring a plurality of lines longitudinally across the back surface, wherein a first longitudinal score line is a first predetermined length X from the first longitudinal edge defining a first longitudinal section, a second longitudinal score line adjacent the first longitudinal score line is a second predetermined length Y from the first longitudinal score line defining a second longitudinal section, a third longitudinal score line adjacent the second longitudinal score line is a second predetermined length  2 X from the second longitudinal score line defining a third longitudinal section, and a fourth longitudinal score line adjacent the third longitudinal score line is the predetermined length Y defining a fourth longitudinal section and the fourth longitudinal score line is the predetermined length X from the second longitudinal edge defining a fifth longitudinal section. The method includes applying sufficient forces on the first longitudinal section and the second longitudinal section in a manner to form an approximately 90 degree bend at the first longitudinal score line and applying sufficient forces on the fifth longitudinal section and the fourth longitudinal section in a manner to form an approximately 90 degree bend at the fourth longitudinal score line. The method further includes applying sufficient forces on the second longitudinal section and the third longitudinal section in a manner to form approximately 90 degree bend at the second longitudinal score line and applying sufficient forces on the third longitudinal section and the fourth longitudinal section in a manner to form approximately 90 degree bend at the third longitudinal score line thereby causing the first and second longitudinal edges to abut. The method further includes applying a weld on the the first and second longitudinal edges to form a rectangular steel pipe. 
     The method can provide score lines by way of a stamping tool. The tool can also include a die tool face to provide the score lines and optionally other desired features in the pipe, such open surfaces in one or more of the longitudinal sections which can be coaxial aligned, for example. 
     A steel pipe is provided which includes a steel plate formed with at least four sides of equal length and having opposing sections of equal width wherein all sides have a predetermined thickness, including two outermost sections welded together at a respective outermost edge thereof, and each remaining section integrally connecting to another section generally at a 90 degree bend and having a scoring line internally formed longitudinally across an internal surface which serves to impart the 90 degree bend. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic of forming a square steel pipe of the instant invention. 
         FIG. 2A  is a schematic of forming a rectangular steel pipe of the instant invention. 
         FIG. 2B  is another schematic of forming a rectangular steel pipe of the instant invention. 
         FIG. 3  is a schematic of a stamping mechanism to form the steel pipe of the instant invention. 
         FIG. 4  is an exploded view of a part of  FIG. 3 . 
         FIG. 5  shows a plate of the invention with score lines for forming a square pipe. 
         FIG. 6A  shows another plate of the invention with score lines for forming a rectangular pipe. 
         FIG. 6B  shows still another plate of the invention with score lines for forming a rectangular pipe. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, the process and method of forming the steel square or rectangular shaped tubular pipe of the invention is generally referred to by the numeral  10 , wherein like parts include like numerals. The invention provides a stamping tool  12  having s plurality of precision formed cutting/scoring die faces  14  that score or cut and form score lines  18  on steel plate  20  into a desired shape or profile. The die face  14  is made from hardenable tool steel and contain cutting and forming sections made from carbide or various other hard, wear-resistant materials. 
     The stamping tool  12  can include one or more angle forming members  16  having a male angled V-shaped face  17  having a leading edge  21  and female angle V-shaped face  19  providing a seat between which the plate  20  is placed in a manner such that a score line  18  aligns with the leading edge  21  of each male angled V-shaped face  17 . In the case of forming the rectangular pipe  150 , there are provided opposing cams  23  and  25  bearing against sides  136 B and  136 D which cause opposing sections (e.g.,  136 A,  136 E) of plate  20  to overlap and spring back to a 90 degree angle as a function of the material strength and memory. In this regard, a drive hump  27  is provided to drive one free section (e.g.,  136 E) under another free section (e.g.,  136 A). 
     Generally speaking, the invention is performed using metal stamping tool  12  to form the shape of the pipe  50 ,  150  along with features, and holes, providing a weld fixture and equipment to form the weld seam on the pipe  50 ,  150  as will be discussed and providing sanding and polishing equipment as needed for the pipe  50 ,  150  to grind/sand the weld seam flush with a wall of the pipe  50 ,  150 . 
     A method of making steel square pipe  50  is provided. In the case of forming a square pipe  50  as in  FIG. 1 , the method includes the following steps. Step one is to provide a generally planar and rectangular or square steel plate  20  having a predetermined thickness, a front surface  22  and a back surface  24 , a first longitudinal edge  26  and a second longitudinal edge  28 , and a first transverse edge  30  and a second transverse edge  32 . Step two is to provide scoring a plurality of lines  34  longitudinally across the back surface  24 , wherein a first longitudinal score line  34 A is a first predetermined length X from the first longitudinal edge  24  defining a first longitudinal section  36 A, a second longitudinal score line  34 B adjacent and parallel the first longitudinal score line  34 A is the predetermined length X therefrom defining a second longitudinal section  36 B, a third longitudinal score line  34 C adjacent and parallel the second longitudinal score line is the predetermined length X therefrom defining a third longitudinal section  36 C, and also is the predetermined length X from the second longitudinal edge  28  defining a fourth longitudinal section  36 D. Step three includes applying sufficient forces on the first longitudinal section  36 A and the second longitudinal section  36 B in a manner to form approximately 90 degree bend at the first longitudinal score line  34 A and applying sufficient forces on the fourth longitudinal section  36 D and the third longitudinal section  36 C in a manner to form approximately  90  degree bend at the third longitudinal score line  34 C, applying sufficient forces on the second longitudinal section  36 B and the third longitudinal section  36 C in a manner to form approximately 90 degree bend at the second longitudinal score line  34 B thereby causing the first and second longitudinal edges  26  and  28  to abut. Step  3  can also include over bending two opposing longitudinal sections (e.g.,  36 A and  36 C) such that the first and second longitudinal edges  26  and  28  temporarily overlap prior to springing back to abutted position. A cam mechanism as described below can be used in this regard. Step  4  includes applying a weld surface  40  on the first and second longitudinal edges  26  and  28  to form square steel pipe  50 . The method can include smoothing the weld surface  40 . 
       FIGS. 2A and 2B  provide exemplary methods for forming rectangular steel tube  150  showing width variations, wherein the method includes the following steps. Step one is providing a generally square or rectangular planar steel plate  120  having a predetermined thickness, a front surface  122  and a back surface  124 , a first longitudinal edge  126  and a second longitudinal edge  128 , and a first transverse edge  130  and a second transverse edge  132 . Step two includes scoring a plurality of lines  134  longitudinally across the back surface  124 , wherein a first longitudinal score line  134 A is a first predetermined length X from the first longitudinal edge  126  defining first longitudinal section  136 A, a second longitudinal score line  134 A adjacent and parallel the first longitudinal score line  134 A is a second predetermined length Y therefrom defining second longitudinal section  136 B, a third longitudinal score line  134 C adjacent and parallel the second longitudinal score line  134 B is a second predetermined length  2 X therefrom defining third longitudinal section  136 C, and a fourth longitudinal score line  134 D adjacent and parallel the third longitudinal score line  134 C is the predetermined length Y therefrom defining fourth longitudinal section  136 D and the fourth longitudinal score line  134 D is the predetermined length X from the second longitudinal edge  128  defining fifth longitudinal section  136 E. Step  3  includes applying sufficient forces on the first longitudinal section  136 A and the second longitudinal section  136 B in a manner to form an approximately 90 degree bend at the first longitudinal score line and applying sufficient forces on the fifth longitudinal section  136 E and the fourth longitudinal section  136 D in a manner to form an approximately  90  degree bend at the fourth longitudinal score line  134 D, and further includes applying sufficient forces on the second longitudinal section  136 B and the third longitudinal section  136 C in a manner to form approximately 90 degree bend at the second longitudinal score line  134 B and applying sufficient forces on the third longitudinal section  136 C and the fourth longitudinal section  136 D in a manner to form approximately 90 degree bend at the third longitudinal score line  134 C thereby causing the first and second longitudinal edges  126  and  128  to abut. This step can include over bending two opposing longitudinal sections (e.g.,  136 B and  136 D relative to  136 C) using the drive hump  27  and cams  23  and  25  such that the first and second longitudinal edges  126  and  128  temporarily overlap prior to springing back to abutted position. The method further includes applying a weld surface  140  on the first and second longitudinal edges  126  and  128  to form rectangular steel pipe  150 . The method can include smoothing the weld surface  140 . 
     The method can provide score lines by way of stamping tool  12  having tool die tool face  14  to provide the score lines and optionally other desired features in the pipe  50 ,  150  to form open surfaces in one or more of the longitudinal sections  36 ,  136  wherein such open surfaces can be coaxial aligned, for example. Steel square and rectangular tubular parts can be manufactured with specific holes, shapes and features in a stamped production process with no or less secondary processes. The die face  14  is configured to score all said scoring lines at once and can be removable to provide such features as required. 
     The stamping process for making the pip  50 ,  150  allows added holes, shapes and features to be incorporated as needed. The weld process can accommodate the finished tubular product by welding only as needed. The sanding/polishing process is used as needed to finish or smooth the exterior of the pipe  50 ,  150  as needed. 
     The invention provides for manufacture of any metal square or rectangular parts. This invention allows steel tubular parts to be manufactured with more detail, less cost and processes, consistent quality, more options for steel types, and more options for sizes of tubing. It minimizes costs and operations for making steel rectangular and square products and assemblies. It allows the ability to minimize the amount of parts to make a product or assembly. It allows the use of different steel types and sizes of shapes. 
     Prior steel square or rectangular shaped tubular parts and products typically made with rolling mills which require pre and post operations for adding additional shapes and holes. Only specific sizes and shapes can be purchased typically. The instant invention solves this problem and provides for more options for sizes and shapes and openings to be formed at reduced cost. 
     Further, in the process of roll milling steel tubular shapes, the metal is stretched and compressed requiring tolerances on the finished product to be increased. The instant invention solves this problem and minimizes the stresses and distortion on the material and makes for a more accurate product. 
     It is to be understood that numerous additions, modifications, and derivations may be made to the present invention which fall within the intended scope of the above description and the claims appended hereto should be afforded the scope of such additions, modifications, and derivations. The configuration and construction materials used in connection with the invention may be modified or changed so long as the intended functionality is neither degraded nor destroyed. There has therefore been shown and described a method of making square and rectangular steel parts which accomplishes at least all of its intended objectives.