Method for producing open-seam pipes from sheet metal panels

Abstract

A method for producing open-seam pipes from sheet metal panels, in particular thick sheet metal panels. A sheet metal panel, having bending edges on the long sides thereof, is fed to a pipe forming press where the sheet metal panel is formed, lying on a lower tool having of two supporting elements which are horizontally spaced apart from each other, by an upper tool, which can be raised and lowered, by application of a bending force, progressively into an open-seam pipe having bending edges on opposite long sides with a gap for later longitudinal seam welding. In order that the sheet metal panel can be easily, progressively formed or shaped from the start, at least the bending sections immediately adjacent on the bending edges of the sheet metal panel are each formed from the outside to the inside, deviating from a numerically ascending bending step sequence in a pilgering process sequence.

Claims

1. A method for producing open-seam pipes from sheet metal panels, comprising: provision of a sheet metal panel having bending edges on the long sides thereof; feeding the sheet metal panel to a pipe forming press in which the sheet metal panel is positioned on a lower tool, wherein the lower tool comprises two supporting elements which are horizontally spaced apart from each other; and progressively forming the sheet metal panel with an upper tool, which can be raised and lowered by application of a bending force, into an open-seam pipe having bending edges on opposite long sides thereof, wherein the open-seam pipe comprises a gap for later longitudinal seam welding, wherein at least two bending sections are reshaped in a pilgering process sequence, each of the two bending sections having an outside corresponding to each of the bending edges and an inside corresponding to a center of the sheet metal panel such that the two bending sections lie adjacent to each other, wherein the pilgering process sequence comprises: identifying a series of bends to be performed on each of the two bending sections, the series of bends to be performed comprising at least a first point, a second point, a third point, and a fourth point, each arranged in numerically ascending order from the outside to the inside of each bending section; performing a bending operation according to a pattern defined by bending the second point first, the first point second, the fourth point third, the third point fourth, in a continuous process, until the series of bends is complete.

2. The method according to claim 1, wherein for carrying out a second bending step for reshaping each of the first points, which follows a first bending step performed at each of the second points, the sheet metal panel is retracted laterally and initially positioned at a non-level angle between the lower tool with support of the respective bending edge on one of the corresponding supporting elements.

3. The method according to claim 1, wherein, as the sheet metal panel is progressively formed, a lesser shaped region is produced once each on a left semicircle and a right semicircle of the sheet metal panel relative to a longitudinal axis of the sheet metal panel, the lesser shaped regions resulting in a non-round form of the sheet metal panel; wherein the method further comprises a finishing step in which the upper tool presses upon the non-round form from an exterior of the non-round form and finishes shaping each of the lesser shaped regions to produce the open-seam pipe.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) Further features and details of the invention ensue from the claims and from the following description of an exemplary embodiment of the invention illustrated in the drawings. Shown are:

(2) FIG. 1A in a schematic manner, the start of the shaping of a sheet metal panel according to the prior art on a pipe forming press, proceeding from top to bottom with the initially positioned sheet metal panel

(3) FIG. 1B in a schematic manner, the application of the bending force by a bending rail

(4) FIG. 1C in a schematic manner, the rising bending rail after the application of force

(5) FIG. 2A in a schematic manner, the start of the shaping of a sheet metal panel by the pilgering process, starting with the second bending section on a pipe forming press, proceeding from top to bottom with the initially positioned sheet metal panel

(6) FIG. 2B in a schematic manner, the application of the bending force by the bending rail

(7) FIG. 2C in a schematic manner, the rising bending rail after the application of force

(8) FIG. 3A in a schematic manner, the further shaping of the sheet metal panel with the second bending step, which now follows the first bending step and occurs subsequently in the first bending section, on the pipe forming press, proceeding from top to bottom with the sheet metal panel initially positioned at a steep angle

(9) FIG. 3B in a schematic manner, the application of the bending force by the bending rail

(10) FIG. 3C in a schematic manner, the rising bending rail after the application of force

(11) FIG. 4 a schematically illustrated open-seam pipe showing the bending steps and bending sections in accordance with the pilgering process; and

(12) FIG. 5A a post-forming or reshaping of a non-round preform in at least two-pressing or bending steps, namely, in a first bening step, through application of force on the non-round preform on the left next to the open seam or gap

(13) FIG. 5B a second step after rotation of the non-round preform, in a second bending step through application of force on the right next to the open seam or gap

DETAILED DESCRIPTION OF THE FIGURES

(14) According to FIG. 1, on a pipe forming press 1, which has long been known as such, a sheet metal panel 4, provided with bending edges 2, 3 on the long sides thereof, is shaped or reshaped into a finished open-seam pipe. For support of the sheet metal panel 4 during the reshaping operation, a lower tool 7, consisting of two supporting elements 6a, 6b, which are horizontally spaced apart, is provided, with the reshaping force being applied by a bending rail 8 that can be raised and lowered. At the start of the reshaping operation, the sheet metal panel 4 is positioned in relation to the bending rail 8 in such a way that, during the first reshaping or bending step, the reshaping force exerted by means of the bending rail 8 acts on the first bending section 101 that follows the bending edge 3, with the bending edge 3 being pressed against the supporting element 6b. Through only a small support surface of the bending edge 3 on the supporting element 6b, the bending edge 3 or the sheet metal panel 4 can slip off the supporting element 6b into the clearance 9 between the supporting elements 6a and 6b, as illustrated in FIG. 1c, after which the reshaping operation has to be terminated.

(15) The reshaping of a sheet metal panel 4 into an open-seam pipe 5 in accordance with FIGS. 2 and 3 is carried out in the pilgering process. With reference to the exemplary bending sections 101 to 106 and 107 to 112 as well as 113 of the open-seam pipe 5 in FIG. 4, the first reshaping or bending step is accordingly carried out in the second bending section 102 that follows the bending edge 3. The bending edge 3, extended by the width of the first bending section 101, is pressed with an adequately large support surface against the supporting element 6b and accordingly cannot slip off during the reshaping operation.

(16) For the subsequent bending step, the sheet metal panel is moved laterally to the left by a manipulator, for example, and initially positioned at a steep angle between the supporting elements 6a, 6b on the supporting element 6b with adequate support surface of the bending edge 3 owing to the already reshaped or initially bent second bending section 102. During the second reshaping or bending step, the bending force exerted by means of the bending rail 8 then acts on the first bending section 101 following the bending edge 3 (compare FIGS. 3 and 4 for this).

(17) During the following reshaping or bending steps, the pilgering process can be employed further, whereby the subsequent bending steps then occur in accordance with the sequence of the bending steps 104, 103, 106, 105 for the first or right-side semicircle 10 of the open-seam pipe 5 (see FIG. 4 for this).

(18) For reshaping of the second or left-side semicircle 11 of the open-seam pipe 5, the sheet metal panel 4 is positioned with the bending edge 2 on the supporting element 6a and the bending steps are then carried out in the pilgering process analogously to the already described reshaping of the first semicircle 10 in the sequence, but in the bending sections 108, 107, 110, 109, 112, 111, 113 (see FIG. 4 for this).

(19) In the bending sections 105 and 111, for example, it is possible specifically to carry out a lesser bending of the sheet metal 4 in the remaining bending sections. As a result of this, two regions 12a, 12b, which are less shaped in correspondence to the respective bending step, are present in a defined manner, as illustrated in FIGS. 5A and 5B, so that a non-round, albeit tailor-made preform 13 for the finished reshaping, is obtained.

(20) As shown in FIGS. 5A and 5B, the pressing force for production of the finished open-seam pipe 5, which is to the greatest extent circular as possible, is applied via the bending rail 8 from the outside onto the non-round preform 13.

(21) For this purpose, the non-round preform 13 is positioned in such a way that the region 12a, which lies on the left next to the open seam or gap 14 and is less shaped, is situated at a nine o'clock position, as illustrated in FIG. 5A.

(22) The sequences of this first pressing step of the bending are illustrated in FIG. 5A, proceeding from left to right with the positioned non-round preform 13, the application of the pressing force by the bending rail 8, and the bending rail 8 raised after the application of force.

(23) The second pressing step of the bending is illustrated in FIG. 5B in the same sequence as before. For optimization of the bending torque, the non-round preform 13—here, in its unchanged semicircle 10 on the right—is positioned in such a way that the lesser shaped area 12b on the right next to the open seam or gap 14 assumes a three o'clock position. The pressing force now applied by the bending rail 8 to this side of the preform 13 then brings the non-round preform 13 into the final form of the finished open-seam pipe 5, which is to the greatest extent circular, with a small open seam or gap 14 (FIG. 5B, figure on right) being thereby achieved.