EP1922159B1

EP1922159B1 - Method and apparatus for shaping various cross-sections on metal pipes

Info

Publication number: EP1922159B1
Application number: EP06716821A
Authority: EP
Inventors: Marian Burda; Zbigniew Sowa; Kazimierz Drzal; Adam Maciolek
Original assignee: "Elektromontaz-Rzeszow" SA
Current assignee: "Elektromontaz-Rzeszow" SA
Priority date: 2005-06-15
Filing date: 2006-02-13
Publication date: 2009-04-08
Anticipated expiration: 2026-02-13
Also published as: WO2006135266A1; PL209625B1; PL375719A1; EP1922159A1

Description

The object of this invention is the method and device for shaping various cross-sections on metal pipes, especially those used for lighting post shafts.
Lighting post shafts are known to consist of several sections of steel pipes of different diameters welded together using conical inserts with diameters suitable for pipe sections to be joined.
Polish patent description No. P-360803 , which forms the basis for the preamble of claim 1, reveals also the method and apparatus for producing metal pipe element with different cross-sections. The essence of that method consists in putting a pipe of uniform original diameter into the supports of the apparatus for shaping various cross sections of pipes, so that one face of that pipe rests on the thrust element of the apparatus and, then the other end of that pipe is subjected to expanding operation by pressing in an expander tool of the apparatus with external force of working head to a preset depth (pipe length). Then, the pipe with its one end expanded to larger diameter is reversed on said supports of the apparatus while resting its expanded end against said thrust element of the apparatus and the other, free end of that pipe, having the original diameter, is then shaped to a truncated-cone form, and a conical head with cylindrical rod of a draw unit of the apparatus is inserted into that pipe end and it is clamped to walls of thus formed truncated-cone of the pipe. Then, an external drawing force is applied onto said draw unit. As a result, the end of that original-diameter pipe is subject to drawing operation to get a required consecutive reduced pipe diameter on a specific section, so that there are truncated-cone adapters between the ends of each two different diameters.
The idea of the apparatus for using the above mentioned method consists in its base being provided with at least two supports located between the driving unit, that generates the pressing forces and a tensile force, and its thrust element, whereas the driving unit is equipped with exchangeable work units with functions of expander, die, draw unit and reducing die. The expander of the unit consists of conical head with cylindrical rod and the die has a seat of truncated-cone form, while the draw unit consists of threaded cylindrical drawing rod ending with conical head and pressure sleeve screwed on to that drawing mandrel, whereas the reducing die of the apparatus has the drawhole of its diameter adjusted to required variable original diameter of pipe.
The drawback of the above described method and apparatus is the low quality of surface finish of the final length of pipes obtained as a result of its expansion because of the ovalization and buckling in the middle part, as well as the low quality of the conical surface finish at the other end of the pipe as obtained from the die forming operation. Additional inconvenience of the known solution is the risk of breaking the thread on head mandrel as it passes through the reducing die with consequential risk of the head being pulled out from the conical end of the pipe.
The purpose of the invention is to eliminate completely the above mentioned drawbacks and inconveniences of the state-of-the-art solutions.
The essence of the method of this invention is that one end of pipe of uniform original diameter is expanded to a required enlarged diameter when it is put into forming clamp of the same diameter, whereas, prior to forming the other end of the pipe of original diameter to cylindrical-and-conical form, several equally-spaced and preferably-triangular-like cutouts are made on its face and on its circumference and, when the other end of the pipe of original diameter is drawn to a required diameter, the conical-and-cylindrical end of the pipe is clamped between goffered surfaces on external surface of conical-and-cylindrical head and on internal surfaces of the conical section of the pressing sleeve of the draw unit of the multi-functional apparatus.
The essence of the multi-functional apparatus for shaping varying cross sections of pipes of this invention is that its base is additionally equipped with forming clamp for one end of pipe located between the support and the expander guide, whereas the external surface of the conical-and-cylindrical draw unit and the internal surface of the conical section of the pressing sleeve of this unit are goffered circumferentially.
The application of forming clamp of this invention to function as a calibrating element and putting a pipe into it for the end expanding operation makes the wall of expanded pipe to adhere to the clamp wall and the expanded pipe section has identical, uniform diameter and smooth surface all along that section. On the other hand, making of triangular cutouts, equally spaced on the circumference, at other end of the pipe, eliminated the risk of folds being created on the surface of the taper formed in the die. Besides, thanks to the application of circumferential goffering on surfaces of the conical-and-cylindrical head and that of the pressing sleeve of the drawing unit, the wall of the conical-and-cylindrical section at the pipe end is clamped from both sides between those gofferings and prevents this section from straightening and/or the drawing head from pulling of out of it.
The object of this invention is shown in the examples of its embodiment in drawings, where fig. 1 is a diagram showing the apparatus for shaping various cross-sections of metal pipes over required lengths, fig. 2 is the enlarged, exploded view of the draw unit of the apparatus in its front view of its mandrel with head and in axial view of its pressing sleeve, figs. 3-10 show individual stages of shaping three different pipe cross-sections along its sections, wherein fig. 3 shows the original pipe of uniform diameter all over its length in its front view, fig. 4 shows the same pipe clamped in the apparatus for shaping different pipe cross-sections in the process of expanding one of its ends and enlarging pipe diameter along a specific length, fig. 5 shows the fragment of pipe end with triangular cutouts on its face in the front view and as seen from its face, fig. 6 shows the same pipe clamped in the same apparatus in the process of forming the pipe end with triangular cutouts to a truncated cone in its front view, fig. 7 shows the same pipe clamped in the same apparatus in the process of drawing the pipe end through a reducing die in order to obtain a third section of the pipe with smaller diameter than the original diameter and the diameter obtained as a result of expending, in its front view, fig. 8 shows the fragment of the draw unit of the apparatus in the process of drawing the end of original diameter pipe, fig. 9 shows the pipe thus made with three different diameters and conical transitions between them in a front view and fig. 10 shows the fragment of the same pipe end with formed truncated cone in front view.
The multifunction apparatus for shaping various cross-sections of pipe(s) along required lengths as shown in fig. 1, has a base 1 for connecting its two other units comprising: the driving unit 2 that enables application of axial forces F ₁, F ₂ and F ₃ and generating a reciprocating movement of its exchangeable work units. The base 1 of the apparatus is also equipped with two sleeve supports 3, a thrust element 4 in its rear section and the clamp 5 for forming the expanded end of the pipe in its front section, whereas the drive unit 2 is equipped with exchangeable work units: expander 6, die 7, draw unit 8 and reducing die 9.
Expander 6 of the apparatus consists of the cylindrical mandrel 10 ending with conical-and-cylindrical work head 11 and the thrust ring 12 loosely mounted on the guide 13 of apparatus. The die 7 of the apparatus has a seat 14 of truncated cone profile, whereas the draw unit 8 consists of threaded cylindrical drawing rod 15, ended with cylindrical-and-conical head 16, provided with circumferential goffering 17 on its external surface, and the pressing sleeve 18 with its internal conical part also provided with circumferential goffering 19, whereas said sleeve is pressed with nut 20 screwed onto cylindrical rod 15. In turn, the reducing die 9 of the apparatus has an drawhole 21 of diameter adjusted to required other diameter of the pipe 22.
The method of shaping various cross-sections at the ends of metal pipe consists in the pipe 22 of original diameter d _w and original length L _w being mounted in the multifunctional apparatus so, that its middle part is placed in two sleeve supports 3 and one of its faces rests against a thrust element 4 of the apparatus whereas the other end of that pipe is put into forming clamp 5 of diameter d ₁ larger than the original diameter d _w of the pipe 22 and is subjected to expanding operation by the work head 11 of the expander 6 with external compressing force F ₁ to obtain pipe end section along the length L ₁ with required expanded diameter d ₁ equal to the inner diameter of the forming die 5 with conical transition 23 between diameters d _w and d ₁ of the pipe. Then the pipe 22 with its one end expanded is removed from the multifunctional apparatus and four equally spaced triangular 24 cutouts are made in the face and the circumference at the other end of the pipe with original diameter d _w. Then the pipe is again put into the apparatus in sleeve supports 3 of the apparatus with the face of expanded end rested against the thrust element 4 and the other end of the pipe having the original diameter d _w is formed to cylindrical-and-conical shape 25 with the use of die 7 of the apparatus, while exerting the compressing force F ₂. As a result, the cutouts/tongs 24 on the profile so shaped will be pressed together and leaving small, tear-drop-like cutouts 24' on the circumference. Then a cylindrical-and-conical head 16 of the draw unit 8 is inserted into so shaped cylindrical-and-conical section 25 of the pipe 22 from the direction of its expanded end, and a pressure sleeve 18 is mounted at the cylindrical-and-conical end of the pipe with a nut 20 screwed onto cylindrical rod 15 of that unit, thus causing a clamping of that end between goffered surfaces 17 and 19 of this head and that of the pressing sleeve. Then an external tensile force F ₃ is exerted onto the cylindrical-and-conical head 16 and, as a result, the end of the pipe with original diameter d _w is subjected to drawing through the drawhole 21 of the reducing die 9 until it acquires the required smaller diameter d ₂ along the length L ₃ of this pipe with conical transition 26 between diameters d _w and d ₂, while retaining the section of the pipe with original diameter d _w along the length L ₂.
The method and the apparatus of this invention find application for shaping various cross sections of pipes made of steel, aluminum and aluminum alloys.

Claims

Method of shaping various cross-sections on metal pipes (22), especially those used for lighting posts, wherein the pipe (22) of uniform original diameter (d_w) all over its original length (L_w) is mounted in apparatus so, that its middle part is placed in two sleeve supports (3) and one of its faces rests against a thrust element (4) of the apparatus, whereas the other end of that pipe is subjected to expanding operation with external axial compressing force (F₁), the pipe (22) with its one end expanded to larger diameter (d₁) being then removed from the apparatus and put again into the apparatus in sleeve supports (3) of the apparatus with the face of expanded end rested against the thrust element (4) of the apparatus and the free end of the pipe (22) having the original diameter (d_w) being formed to cylindrical-and-conical shape (25) with the use of the die (7) of the apparatus while exerting the compressing force (F₂), and then a cylindrical-and-conical head (16) of the draw unit (8) is inserted into this end and it is fixed to the walls of previously formed cylindrical-and-conical part (25) of the pipe and an external tensile force (F₃) is exerted onto said head (16), so that the end of the pipe is subjected to drawing through the drawhole (21) of the reducing die (9) of the apparatus until it acquires the required diameter (d₂), smaller than the original diameter (d_w), characterized in that the process of expanding one end of the pipe (22) of original diameter (d _w) to required diameter (d ₁) is carried out in additional mounting in a forming clamp (5) of the same diameter (d ₁) whereas prior to forming the other end of the pipe (22) of the original diameter (d _w) to cylindrical-and-conical shape (25) several cutouts (24) of preferably triangular-like profile are made at equal space on pipe face and circumference and the process of drawing the other end of the pipe (22) of original diameter (d _w) to required diameter (d ₂) is carried out while clamping the cylindrical-and-conical end of the pipe between goffered surfaces (17 and 19) of the external side of the cylindrial-and-conical head (16) and the internal side of the pressing sleeve (18) of the draw unit (8) of the multifunctional apparatus.
Multifunction apparatus for shaping different cross-sections on pipe (22) having a base (1) equipped with at least two supports (3) for the pipe (22) located between a drive unit (2) for application of axial compressing forces (F₁, F₂) and axial tensile force (F₃) and a thrust element (4), the drive unit (2) being equipped with exchangeable work units with functions of expander (6), die (7) for forming the cylindrical-and-conical profiles, reducing die (9) with drawhole (21) and a drawing vod (15) consisting of cylindrical-and-conical work head (16), pressing sleeve (18) and nut (20) screwed onto the drawing rod (15) wherein the base (1) of said apparatus is additionally equipped with a forming clamp (5) for forming in cooperation with the expander (6) one end of the pipe (22), said forming clamp (5) being located between the support (3) and the guide (13) of expander (6), whereas the external surface of the conical-and-cylindrical head unit (16) of the draw unit (8) and the internal surface of the conical part of the pressing sleeve (18) of this work unit are provided with circumferential goffering (17) and (19).