MULTI-WALL METAL ROLL FORMING ASSEMBLY TECHNICAL FIELD

The present invention relates to cold forming assemblies providing production of a multi-wall tube, particularly double-layered tube by means of bending metal sheet profile along a line. KNOWN STATE OF THE ART

In the production of a metal tube having a multi-wall cross section, particularly in the production of a double-layered steel tube, another metal material, for instance, a steel sheet coated with copper is horizontally fed to a roll forming assembly having a width determined in accordance with the diameter of the tube which is desired to be obtained. Obtaining a multi- layered tube by means of rolling the horizontally extending metal sheet from the end section of said metal sheet in a stepped manner is called Bundy process, and it has been disclosed by the US patent US1431368. In realization of the bending process of the metal sheet, roll forming, which is a cold shaping method, is used. Accordingly, the bending stations, positioned successively in a spaced apart manner, provide a roll form to the metal sheet in a stepped manner. In each bending station, there are two cylindrical rollers, having a spaced apart section formed in between and extending in the horizontal axis one above the other, and there are rotating rollers extending in the vertical axis in the following section. The distance between the axes of the rollers and the cylinders is adjusted such that the coated metal sheet, advancing in the horizontal direction in each bending station, is bent in a stepped manner and takes the form of a tube. In each bending station, the compression force is realized in two mutual directions with the help of arms named as studs by means of the vertical upper roller and the vertical lower roller. However, in this applied method, the pressure, provided through the stud arms, may not be equal to each other. BRIEF DESCRIPTION OF THE INVENTION

The object of the present invention is to provide equal distribution of the stress applied to the metal sheet during cold shaping in multi-wall metal tube production.

In order to achieve said object, the present invention is a multi-wall metal sheet roll forming assembly comprising an upper roller where a metal sheet strip is fed in a lengthwise manner and having a rotation axis adjusted in a parallel manner to the extension axis of the metal sheet strip, and an adjacent lower roller where a processing surface, which bends the metal sheet strip during rotation, is provided between said lower roller and said upper roller. The metal sheet roll forming assembly comprises a bearing element which holds the upper roller in a manner allowing rotation from the two mutual rotation ends, and a drive mechanism adapted to the bearing element in a manner exerting equal compression force through the mutual rotation ends towards the lower roller. The equal pressure provides the metal sheet strip, which advances between the upper roller and the lower roller, to be continuously subjected to equal stresses during the cold shaping process. In this case, the stresses, provided on the cross section of the multi-layered tube which is the product of the metal sheet roll forming assembly, are equally distributed along the length, and a product, which is compliant to the predetermined standards in accordance with the application areas, is obtained.

In a preferred embodiment of the invention, a guiding housing is provided wherein the bearing element is placed in a manner allowing movement of the bearing element in a guiding direction where the bearing element is pressed against the lower roller. The bearing element moves inside the guiding housing and carries the upper roller towards the lower roller. Thus, the bearing element is forced to move within a predetermined route, and the bearing element is facilitated to be configured in a manner providing exertion of equal force after various usages. In a preferred embodiment of the invention, the guiding direction of the guiding housing is configured in a manner following a linear path between the upper roller and the lower roller. The linear movement allows operation by means of the drive assembly pushing the bearing with a simple stroke. In a preferred embodiment of the invention, a casing is provided where the guiding housing is provided on the mutual side walls of the casing and where the drive assembly is aligned at the upper section of the upper roller on a ceiling section which joins the side walls. The casing carries the upper and lower roller by means of a compact structure. By means of this, a modular production system is obtained, and it becomes possible to process the metal sheet strip in a stepped manner thanks to the placement of the casings one after the other. In a preferred embodiment of the invention, the drive assembly comprises a shaft extending in the guiding direction. The shaft transfers the force, provided by the drive assembly, to the bearing element in a linear manner.

In a preferred embodiment of the invention, a motor is provided whereto the shaft is mounted in a rotating manner from one end, and the bearing element comprises a screw housing which corresponds to a threaded free end of the shaft. The threaded end rotates inside the screw housing, and it provides advancing of the bearing element. By means of rotation of the shaft, even if the bearing is made of a heavy material like cast iron, it rotates inside the screw housing and it is easily guided.

In a preferred embodiment of the invention, at the intermediate section of the bearing element, there is a first arm which bears the rotation end whereto the drive assembly exerts force and there is a second arm which bears a second rotation end. The force is distributed equally by means of a compact structure thanks to the application of drive through the intermediate section where the two arms of the drive assembly join.

In a preferred embodiment of the invention, the first arm and the second arm have mirror- symmetry with respect to the position of the drive assembly on the bearing element. The mirror symmetry helps the arms to provide equal load distribution.

In a preferred embodiment of the invention, the drive assembly is aligned coaxially with the processing surface on the bearing element. By means of this, the upper roller can directly transfer compression force on the lower roller at the section where process is realized. Moreover, the effect of the vibration, formed on the upper and lower roller by the counter forces caused by the metal sheet strip on the processing surface, is minimized.

In a preferred embodiment of the invention, an indicator is provided which is configured in a manner illustrating the compression force, exerted by means of the drive assembly, in a visually accessible manner.

In order to reach said object, a preferred embodiment of the invention is a tube production method by means of a multi-wall metal sheet roll forming assembly comprising the process steps of pushing the upper roller towards the lower roller by the bearing element by means of the drive assembly in a manner shifting a predetermined compression force which is equally distributed at both rotation ends; and feeding the metal sheet strip by means of aligning the metal sheet strip in a manner contacting the processing surface along an edge of the processing surface between the upper roller and the lower roller.

By means of a preferred application of the subject matter invention, in the roller system comprising the upper and lower roller, the metal sheet, which passes through the sheet shaping unit, is brought into tube form by means of bending, and the pressure of the upper roller onto the lower roller is distributed to the lower roller equally from a single point by means of the drive assembly instead of two arms. The measurability of the pressure exerted by the upper roller onto the lower roller and stability of said pressure along the line increase product quality. BRIEF DESCRIPTION OF THE FIGURES

In Figure 1 , the lateral schematic view of a bending station provided in a representative application of the subject matter multi-wall metal sheet roll forming assembly is given. In Figure 2, the lateral view of a metal sheet roll forming assembly where the bending station illustrated in Figure 1 is placed one after the other is given in the condition of the metal sheet being fed.

In Figure 3, the frontal schematic view of a bending station used in the multi-wall metal sheet roll forming assembly is given.

DETAILED DESCRIPTION OF THE INVENTION

In this detailed description, a roll forming assembly and method, designed for use in production of double-layered steel tube coated with copper, is explained with references to examples without forming any restrictive effect only in order to make the subject more understandable.

With reference to Figure 1 , a bending station (3) has a circular indicator (2) which can be visually easily accessed when viewed from the lateral side. In general, a casing (10) forming a frame is made of metal material. On a side wall (16) of the casing (10), there is a long rectangular guide housing (14) in a manner forming two columns extending between the upper section (12) and the intermediate section thereof. At the lower section of the guide housing (14), a lower roller (50) is rotatably supported in a manner extending in a horizontal rotation axis (x). The lower roller (50) is provided at a lower section (13) of the casing (10). A base (1 1 ) of the casing (10) is in planar form and it is adjusted in a manner erecting the casing (10) by means of sitting on the floor. Inside the guide housing (14), a bearing element

(20) and an upper roller (40) fixed to the bearing element (20) through a connection section

(21 ) pass in a manner guided linearly from one end. The upper roller (40) extends in the rotation axis (x), which is the horizontal axis, in a parallel manner to the lower roller (50). A drive assembly (30) is fixed to a ceiling section (17) of the casing (10). The drive assembly (30) carries the bearing element (20) in a manner permitting advancing of the bearing element (20) at a lower free end of a shaft (35) which is in vertical position. The bearing element (20) has freedom to advance along the length of the guide housing (14) together with the upper roller (40) carried together inside the guide housing (14) where a first arm (22) of the bearing element (20) passes through the end thereof. The lower edge of the guide housing (14) defines a stopper surface (15). The upper roller (40) sits onto the stopper surface (15) at its lowermost position; and the advancing movement is restricted.

In Figure 2, the bending stations (3), arranged in a spaced apart manner one after the other on a floor, are illustrated together in a manner forming the roll forming assembly (1 ). A metal sheet strip (7), obtained by means of copper coating over steel, is fed to the first bending station (3) through an inlet section. There is a horizontal roller assembly (6) between both adjacent bending stations (3). By means of this, the metal sheet strip (7) is bent in a stepped manner while passing through each bending station (3), and it takes the form of a double- layered tube. The upper roller (40) and the lower roller (50) shape the metal sheet strip (7) by means of exerting pressure from the upper side and from the lower side, and the vertical roller assembly having vertical rotation axis exerts pressure through the lateral sections, and they provide completion of the bending process in a stepped manner in the advancing direction. In Figure 3, the frontal view of the bending station (3) is given. The casing (10) is inverse U form. The drive assembly (30) is placed onto the upper section (12). In the drive assembly (30), the motor (8) extends laterally, and it is connected to a reducer (32). There is a vertical transmission element (34) at the lower end of the reducer (32). The vertical transmission element (34) bears a shaft (35) extending in the vertical direction. Screw thread is formed on the shaft (35) towards the lower end until a free end (37) thereof. At the upper section (12) ceiling of the shaft (35), there is an upper sleeve (33). On the other hand, a screw housing (36) corresponding to the upper sleeve (33) is provided at the bearing element (20) from an upper section. The screw housing (36) wraps the shaft (35) in sleeve form, and it transfers the rotational movement of the shaft (35) as advancing movement to the bearing element (20). The bearing element (20) extends towards the corresponding side walls (16) in a manner forming the first arm (22) and a second arm (25) which is symmetrical with respect to the first arm (22) in the vertical axis. Thus, the first arm (22) is fixed to the rotation end (44) from the lower section, and the second arm (25) is fixed to the second rotation end (45) from the lower section thereof through one each connection section (21 ), and the bearing assembly (20) is fixed to the upper roller (40). The upper roller (40) is in the form of a metal cylinder having sections which widen and narrow in a stepped manner around the processing surface (42) aligned in the intermediate section of the upper roller (40). Correspondingly, there is a lower processing surface (53) sitting onto the lower roller (50) processing surface (42) extending in the horizontal axis in an adjacent manner to the lower side of the upper roller (40), and there is a front surface (52) sitting to the corresponding section at the upper roller (40). The lower roller (50) is fixedly housed in a rotatable manner to the side wall (16) by means of the first lower bearing (54), provided at the mutual ends of the lower roller (50), and by means of the second lower bearing (55).

The metal sheet strip (7) is fed between the lower roller (50) and the upper roller (40) provided above the lower roller (50). The desired upper roller (40) distance is selected through the indicator (2) in accordance with the width of the metal sheet strip (7) and in accordance with the compression force to be exerted. Accordingly, the motor (8) generates high level of torque by means of the reducer (32), and it starts rotating the shaft (35) in the vertical axis which is the guiding direction (y). The shaft (35) moves in the screw housing (36), and it vertically moves the bearing element (20) inside the guide housing (14), and it takes the upper roller (40) to the distance, determined by means of the indicator (2), on the lower roller (50). The bearing element (20) stroke is restricted by means of the upper sleeve (33) from the upper side and the bearing element (20) stroke is restricted by means of the stopper surface (15) from the lower side. In the roll forming assembly (1 ), each bending station (2) is adjusted in a manner providing suitable gap of the upper roller (40) with the help of the motor (8) and the drive assembly (30) in accordance with the metal sheet strip width selected for the double-layered tube production and in accordance with the tube diameter. REFERENCE NUMBERS

1 Roll forming assembly

2 Indicator

3 Bending station

6 Vertical roller assembly

7 Metal sheet strip

8 Motor

10 Casing

1 1 Base

12 Upper section

13 Lower section

14 Guide housing

15 Stopper surface

16 Side wall

17 Ceiling

20 Bearing element

21 Connection section

22 First arm

23 Upper edge

25 Second arm

27 Bridge

30 Drive assembly

32 Reducer

33 Upper sleeve

34 Vertical transmission element

35 Shaft

36 Screw housing

37 Free end

40 Upper roller

42 Processing surface

44 Rotation end

45 Second rotation end

50 Lower roller

52 Front surface

53 Lower processing surface

54 First lower bearing

55 Second lower bearing