Patent Grant
7918380
The invention relates to the manufacture of welded tapered tubes and more particularly to the manufacture of welded tapered tubes having a longitudinal seam.
The present invention relates to the apparatus and process for making an expanded variety of tapered tube sections from formed sheet metal and completed by welding-sizing apparatus of this invention. More specifically, the present invention is a group of apparatuses and processes with intent for welding by electrical resistance method and rolling the welded tube section through sizing apparatus with no means of mandrel or any other internal tool.
It is known in the traditional technology to manufacture tapered tube sections by forming a metal blank which is cut to trapezoidal geometry' out of plate or sheet metal into a conical tube shape and then welding the opposite edges (long side) of the formed blank by an electrical welding method well known as a high frequency welding. However, none of the known methods or apparatus is practical and efficient in operation and pose limitations in terms of tapered tube products geometry such as lengths, diameters or shapes which are to be manufactured. The number of the known apparatuses for manufacturing tapered tube sections in reality is represented by only one particular process. For example, forming, welding or finishing (rolling, burnishing) and some accessories to each one individually. Such disconnects make those apparatuses limited by application.
One example of such prior art practice is found in U.S. Pat. No. 6,629,632 issued to R. Jack and J. Brook and is shown in FIGS. 17 and 18. This invention consists of a “means for applying inwardly directed radial forces to the shaft at a plurality of discrete points on the surface of the shaft [comprising] a plurality of pressure rollers defining an opening through which the shaft is fed, and means for varying the positions of the rollers[.]” One disadvantage of this apparatus and method is the limitation of cross sections to be welded in stable conditions. In other words, when space between rollers grows, material of the tapered tube section will be deformed between rollers under pressure that are intended to be used mostly to create welding fusion. The tapered tube section will be distorted, with increasing distortion toward the larger diameter of the tapered section and exhibit weld defects as well. A second disadvantage of U.S. Pat. No. 6,629,632 is the absence of a secondary operation such as finishing that is required to fix shape discrepancy of the tapered tube section.
Another example of such prior art practice is found in U.S. Pat. No. 3,648,008 issued to T. Kawato et al. Shown is welding apparatus in which “a preformed tapered tube is inserted between miniaturized forming rollers having cam faces . . . and as said tube is drawn . . . the welding is performed on a longitudinal aligned edges of the tube so as to make desired products by means of the comparatively small high-frequency welding apparatus.” This type of roller is known as a “sleep roll” and ensures the tapered tube will be welded, but may not deliver desired shape, size or finishing process at the end.
The next example of such prior art practice is found in U.S. Pat. No. 3,802,239 issued to Karmann et al. This patent discloses an apparatus and process “for forming an elongated tapered tube for use as light poles and the like, the machine comprising means for supporting a flat, trapezoidal sheet of metal in a horizontal position, an elongated mandrel having the shape of the tube to be formed held down along the longitudinal axis of the sheet, a pair of forming elements mounted along each side and below the sheet with power means for raising the formers upwardly and moving them inwardly toward each other whereby to form the sheet about the mandrel, means for flattening the edges of the sheet such that they are contiguous for welding purposes, and means for removing the formed tube from the machine as another sheet is brought into the machine and placed on the supporting means.” This prior art was proposed to finish welded tapered tube by a series of rollers that roll on the outside diameter of tapered lube with a mandrel inside. This type of finishing process required an internal tool along with extra steps to insert the mandrel into the tapered tube and mandrel extraction at the end of the operation. This process will require significant modification to be operated in line with welding apparatus. In addition, because of stretch, the tapered tube will increase in length while the thickness of the tube will decrease.
An additional example of a sizing or finishing practice is found in U.S. Pat. No. 7,296,450 issued to Y. Kuroda. Shown is a “production apparatus for a tapered steel pipe which holds the two ends of the steel pipe by shafts on carriers and moves it in the axial direction while rotating it to draw it to a taper by an intermediate working roll, wherein the shaft of the working roll is inclined 20 to 40 degrees with respect to the axis of the steel pipe and a roll caliber of the working roll is made an outwardly curved surface with little difference in roll peripheral speed; the face plate for mounting the working roll is positioned and supported with respect to the body by a hinge mechanism and is fastened to the body by fastening members; and the bearing of the working roll at the side close to the steel pipe is made smaller than the bearing at the side far from the steel pipe and the two bearings are connected by a tie-rod.” The process has a great deal of limitations as far as tapered tube diameter, shape and length and is extremely dependent upon the wall thickness of the straight tube.
Metal tapered tube product is well known and used as a utility supporting structure in infrastructure, communications and street lighting.
An aspect of the present invention includes providing an improved method and apparatus for manufacturing welded tapered tubes.
A further aspect of the present invention is to provide a metal tapered tube section welding and sizing manufacturing apparatus and process which enables varying 3-D machine geometry in each cycle.
A still further aspect of the present invention is to provide a metal tapered tube section welding and sizing manufacturing apparatus which addresses varying geometry tolerances in the metal blank from which the tapered tube section is made.
A yet further aspect of the present invention is to provide a metal, tapered tube section welding and sizing apparatus and process which addresses varying geometry tolerances in the formed tube piece during forming from the cut metal blank.
Another aspect of the present invention is to provide a metal tapered tube section manufacturing apparatus and process which identifies welding and sizing tooling of the roller position at a registered tapered tube section position.
Still another aspect of the present invention is to provide a metal tapered tube section welding and sizing manufacturing apparatus and process which identifies universal tube position for welding or sizing.
A still further aspect of the present invention is to provide a metal tapered tube section welding and sizing manufacturing apparatus and process which generates forces to close the formed tube piece, originates the weld joint by an electrical resistance weld method and moves the tube section from one end to the other end by powered rolls only and tooling geometry to thereby provide superior weld quality and final shape.
A further aspect of the present invention is to provide an improved welding apparatus and process in conjunction with sizing apparatus and process which accomplishes more than one or all of the above-listed aspects including those obvious to one of skill in the art.
An aspect of the present invention relates to a method and apparatus for manufacturing welded tapered tubes which integrates several processes such as welding and finishing, i.e. sizing. This integration will ensure that the finished product meets the design specifications and is of the highest quality. Moreover, it allows for a wide range of diversity in its application.
Another aspect of the present invention relates to the use of one reference line through the tapered tube section in two different manufacturing sequences by two different apparatuses.
Still another aspect of the present invention relates to a method and apparatus for manufacturing welded tapered tubes in a manufacturing line incorporating the two processes of welding and sizing. This tandem combination of processes enables the finalization of the post-welding shape of the tapered tube section immediately after welding without the need for an internal tool to shape the tube section.
A further aspect of the present invention relates to a processing tool for manufacturing welded tapered tubes which, because of its simplicity of construction, makes it easy to replace, expand and use in universal ways in welding and sizing apparatuses.
A still further aspect of the present invention is the use of original equations to make the processing tool for manufacturing welded tapered tubes easy to size and manufacture. In addition, those equations become a versatile tool to engineer the processing tool for manufacturing welded tapered tubes regardless of scale or application.
This invention provides an improved apparatus and process for welding tapered tube sections of different shapes and sizes from previously formed shells from flat metal of different gauges by using solid state electrical resistance welding method. This invention provides a novel apparatus and process for sizing and finishing in line with improved welding apparatus that will guarantee proper roundness with close round tolerances to the tapered tube sections. The sizing process is based upon “squeezing” the tapered tube section past its yield strength to give the tapered tube section required roundness at close round tolerances.
According to the present invention, a tapered tube manufacturing apparatus, comprises an entry station adapted to receive a tapered tube having an open, longitudinal seam with spaced longitudinal edges extending the length of the tapered tube; a feed line section moving the tapered tube from the entry section into a welding station while maintaining the longitudinal seam coincident with a pass center line (PCL) which defines a direction of movement of the tapered tube through the entry station, the feed line section and the welding station; a pair of squeeze rolls in the welding station for moving the tapered tube through the welding station where the edges of the seam are heated, squeezing the open seam closed for welding the edges of the seam together, and moving the welded tapered tube into a cooling and transition station while maintaining the welded seam coincident with the pass center line (PCL); and a pair of sizing rolls for moving the welded tapered tube from the cooling and transition station and through the sizing station so that a centerline (CL) extending longitudinally through the center of the welded tapered tube is coincident with the direction of movement of the welded tapered tube through the sizing station and the welded tapered tube is squeezed so that all cross sections of the welded tapered tube that are perpendicular to the centerline (CL) at any point along the length of tube, have the same shape.
According to the present invention, a tapered tube manufacturing apparatus comprises a series of stations, including an entry station, a feed line section, a welding station, a cooling and transition station, and a sizing station.
Further according to the present invention, the initial station, an entry station, is adapted to receive a tapered tube with a longitudinal seam extending the length of the tube. The entry station may include a pusher mechanism for pushing the tapered tube into squeeze rolls at the subsequent welding station. The entry station may also include a conveyor to support the tapered tube as it moves toward the feed line section.
Still further according to the present invention, the next station, the feed line section, moves the tapered tube from the entry station toward the welding station while keeping the seam coincident with a pass center line that delineates the direction of movement of the tapered tube through the various stations. The feed line section may include a fin plate approximately as long as the tube disposed between the open edges of the seam to maintain the position of the seam relative to the pass center line. The fin plate can also include a flange disposed within the tapered tube to support it along its length.
Also according to the present invention, the next station, the welding station, includes an induction heating system for heating the edges of the open longitudinal seam. The welding station also has a pair of squeeze rolls to squeeze the seam together to seal the edges as they are welded together and to move the tapered tube into a cooling and transition station. Each of the squeeze rolls may have tooling located around its circumference forming a radial contour in a mirror arrangement of the opposite squeeze roll. The size of the radial contour itself may change to accommodate the shape and size of individual tapered tubes. In general the radial contours of the master plate create a circular opening with a diameter approximately 94% to 98% of a diameter through the tapered tube section.
Moreover according to the present invention, the next station, a cooling and transition station may feature a clamp cart to support an end of the welded tapered tube section. It may also include a pusher plate to push the tube forward and a support roll to elevate the welded tapered tube such that the longitudinal center line through the length of the tube aligns with the line of movement of the tube through the tube manufacturing apparatus.
According to the present invention, the next station, a sizing station includes a pair of sizing rolls that move the tapered tube along from the cooling and transition station, such that the center line extending longitudinally through the center of the welded tapered tube is coincident with the direction of movement of the welded tapered tube through the sizing station. As with the squeeze rolls, the sizing rolls may have tooling located around its circumference forming a radial contour in a mirror arrangement of the opposite squeeze roll and the size of the radial contour may change to accommodate the shape and size of individual tapered tubes.
The invention also includes a method for manufacturing a tapered tube including the steps of moving a tapered tube having an open longitudinal seam with spaced longitudinal edges extending the length of the tapered tube through an entry station. Then, the tapered tube is moved from the entry section into a welding station while maintain the open longitudinal seam of the tapered tube coincident with a pass center line (PCL) which defines the direction of movement of the tapered tube through the entry station and the welding station. Next, the open seam is squeezed closed and the edges of the seam are welded together. Then, the welded tapered tube is moved through a cooling and transition station while maintaining the movement of the welded tapered tube so that the welded seam is coincident with the pass center line (PCL). Next, the welded tapered tube is moved through a sizing station so that a centerline (CL) extending longitudinally through the center of the welded tapered tube is coincident with the direction of movement of the tapered tube through the sizing station. Next, the welded tapered tube is squeezed in the sizing station so that a cross section of the welded tapered tube that is perpendicular to the centerline (CL) at any point along the length of tube is circular.
The structure, operation, and advantages of the present invention will become further apparent upon consideration of the following description taken in conjunction with the accompanying figures (FIGs.). The figures are intended to be illustrative, not limiting. Certain elements in some of the figures may be omitted, or illustrated not-to-scale, for illustrative clarity. The cross-sectional views may be in the form of “slices”, or “near-sighted” cross-sectional views, omitting certain background lines which would otherwise be visible in a “true” cross-sectional view, for illustrative clarity.
If shading or cross-hatching is used, it is intended to be of use in distinguishing one element from another (such as a cross-hatched element from a neighboring un-shaded element. It should be understood that it is not intended to limit the disclosure due to shading or cross-hatching in the drawing figures.
Elements of the figures may (or may not) be numbered as follows. The most significant digits (hundreds) of the reference number correspond to the figure number. For example, elements of
In the drawings accompanying the description that follows, both reference numerals and legends (labels, text descriptions) may be used to identify elements. If legends are provided, they are intended merely as an aid to the reader, and should not in any way be interpreted as limiting.
In the description that follows, numerous details are set forth in order to provide a thorough understanding of the present invention. It will be appreciated by those skilled in the art that variations of these specific details are possible while still achieving the results of the present invention. Well-known processing steps and materials are generally not described in detail in order to avoid unnecessarily obfuscating the description of the present invention.
In the description that follows, exemplary dimensions may be presented for an illustrative embodiment of the invention. The dimensions should not be interpreted as limiting. They are included to provide a sense of proportion. Generally speaking, it is the relationship between various elements, where they are located, their contrasting compositions, and sometimes their relative sizes that is of significance.
Referring to
The operations described with respect to
The tapered tube manufacturing apparatus 22 takes a preformed piece of metal 16, generally in the circular “C” shape (see
The entry station 20, as best shown in
The feed line section 26, shown in
Note that the initial PCL extends longitudinally along the seam or slot 16c and is parallel to direction of movement of the tapered tube 16 through the tapered tube manufacturing apparatus 22.
Moving the un-welded tube section 16 so that the PCL is parallel to the direction of movement enables for ease in movement of the tube section 16 because it can be moved with the edge of the slots parallel to the direction of movement and the manufacturing floor 44. This is particularly useful when the tube section is moved though the welding section, as discussed below.
Referring to
Welding station 28, as best shown in
Rollers 60, 62 and driven sprockets 74, 76 are bearing-mounted on the shafts 82, 84. The shafts 82, 84 are fixed through the bottom mounting brackets 94, 96, respectively, are affixed to the welding station base 98. At the top end, shafts 82, 84 are affixed to the overhead structures 100. Overhead structures 100 are also affixed to the welding station base 98. The overhead bridge platform 102 acts as a master base for the electrical resistance welding unit 104, that is mounted over the top of both squeeze rolls 60, 62 close to the center line though direction of movement through the tapered tube manufacturing apparatus 22.
As shown in
A seam guide roll assembly 108 will be mounted off the structural support frame which is affixed to the bridge 102 and will be located in front of the two squeeze rolls 60, 62 so that the weld contacts 106 are between the seam guide roll assembly 108 and the squeeze rolls 60, 62. The seam guide roll assembly 108 includes a lip 109 disposed through the seam 16c of the tube 16 that ensures the proper presentation of the tube into the squeeze rolls 60, 62.
Immediately following the weld station 28, an outside diameter (OD) trim assembly (not shown) can be provided to cut the red-hot outside bead resulting from the “squeeze”/welding operation. The OD trim assembly can be affixed to the overhead bridge 102. The trim will be accumulated on a winding mechanism from which it will be removed as needed. The welding of the tapered tube section 16 will be performed with its top surface in a horizontal position The PCL, see
The welded tapered tube section 40 (see
During the welding process, the small end 40a of the tapered tube section that was welded first will be moved into the cooling station 34 and will be self-clamped by a clamp cart 110 (See
The shaped clamp tool 116 is bolted to the clamp cart 110. The shaped part 118 is attached to the part 116 by a hinge pin 24 and has a cam roller 122 attached thereto. Cam roller 122 is engaged by cam arm 124 which is connected to a cam arm air cylinder 126. As cam arm air cylinder 126 stays closed, the tapered tube section is clamped (
After the welded tapered tube section 40 will rest on the chain conveyer 128 with a pusher plate attached, the chain conveyer 128 will push the tapered tube section forward to the sizing station 36. As soon as the welded tapered tube section 40 reaches support roll 132, see
Chain conveyer 128 will continue to move the welded tapered tube section 40 (
The sizing station 36 is shown in
The removal station 42 of the tapered tube section manufacturing apparatus 22 consists of a powered roll conveyor 152 equipped with lift-off arms (not shown) to remove the finished (welded and sized) tapered tube section 40 onto a skid table or any other supporting structure to accommodate present product well known in the art as material handling accessories.
In the embodiments previously described and shown in
The tooling 150, illustrated in
The combination of radial contours 162 which are a mirror arrangement of the radial contours of the master plate located on the opposite facing surface of squeeze rolls 60, 62 or sizing rolls 134, 136 creates a circular opening with a diameter that that is between about 94% to 98% of a diameter through the tapered tube section 16 with an open seam or the welded tapered tube section 40. See
The formulas and equations hereinafter are for the tooling and roll (squeeze or sizing) geometry. The formula for weld roll work diameter is a function between tool base radius R, distance between rolls, and master plate squeeze diameter d. Formula 1 is used to determine spacing between master plates and is a function between roll circumference L, thickness of master plate t, number of master plates per roll N. Formula 2 provides that an incremental difference between master plate squeeze diameters is a function between the roll work diameter at small and large ends of the tapered tube section and the number of master plates n per initial angle of the roll.
Formula 1
Roll work Diameter (Dw);
Dw=2×[r+s/2)−d/2]
r—tool base radius
s—distance between rolls at the bottom
d—master plate squeeze diameter
Formula 2
Master plate spacing (St):
St=[L−(t×N)]/(N−1)
L—roll circumference, L=Dw×? (inches)
t—master plate thickness
N—number of master plates per roll
Formula 3
Incremental difference between master squeeze diameters (Sd):
Sd=(Dw1−Dw2)/N
Dw1—roll work diameter at large end
Dw2—roll work diameter at small end
R1—roll work radius at large end
R2—roll work radius at small end
Number of master plates per initial angle (N):
N=Dwi/Dw2 min=RI/R2 min
The Formula 1 for weld roll work diameter is a function between tool base radius r, distance between rolls, and master plate squeeze diameter d.
Formula 2 is used to determine the spacing between master plates and is a function between roll circumference L, thickness of master plate t, number of master plates per roll N.
Formula 3 provides an incremental difference between master plate squeeze diameters and is a function between roll work diameter at small and large ends of the tapered tube section and the number of master plates (n) per initial angle of the roll.
Accordingly, the improved tapered tube section manufacturing apparatus and process with a number of novel mechanisms and approaches in technology provides an effective, inexpensive and efficient manufacturing cell which achieves all the enumerated aspects, provides for eliminating disadvantages encountered with prior apparatuses, devices and processes, and obtains new directions in technology and new results in the art.
Having now described the features, discoveries and principles of the invention, the manner in which the tapered tube section manufacturing apparatus and process is constructed and used, the characteristics of the construction, and the advantageous, new and useful results obtained; the new and useful structures, devices, elements, arrangements, parts and combinations in engineering art, are set forth in the following claims.
| Number | Name | Date | Kind |
|---|---|---|---|
| 3452424 | Morris | Jul 1969 | A |
| 3648008 | Kawato et al. | Mar 1972 | A |
| 3802239 | Karmann et al. | Apr 1974 | A |
| 3920173 | Salata | Nov 1975 | A |
| 3945552 | Tobita et al. | Mar 1976 | A |
| 4846392 | Hinshaw | Jul 1989 | A |
| 6629632 | Jack et al. | Oct 2003 | B1 |
| 7296450 | Kuroda et al. | Nov 2007 | B2 |
| 20080230586 | Kenmochi et al. | Sep 2008 | A1 |
