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 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 supporting 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 £ and reducing die 9.

Expander 6 of the apparatus consists of the cylindrical mandrel K) ending with conical- and-cylindrical work head ϋ 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 lj£ 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 _π and original length L _π 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 dj_ larger than the original diameter dw of the pipe 22 and is subjected to expanding operation by the work head ϋ of the expander 6 with external compressing force Fi to obtain pipe end section along the length L ₂ , with required expanded diameter d^ equal to the inner diameter of the forming die 5. with conical transition 23 between diameters d _w and dj_ 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^. 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 241 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 Fj is exerted onto the cylindrical-and-conical head 16 and, as a result, the end of the pipe with original diameter d _H is subjected to drawing through the drawhole 2J. of the reducing die 9 until it acquires the required smaller diameter dg along the length L ₃ of this pipe with conical transition 26 between diameters d _w and dg, while retaining the section of the pipe with original diameter dw 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.