RU2505370C1 - Method and device for manufacturing of pipes with butt weld made from metal sheets - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: metal sheet is delivered to O-forming press (1), in which it is formed at stages in a pipe (4; 104) with butt weld under impact of bending. During this process the sheet is placed on lower stamp (6) and upper stamp (9) is lifted up and down. At first a pipe with a butt weld of out-of-round blank mould (13) is formed. For this purpose at least at one stage of bending impacting inner side of metal sheet (3) correspondingly from the right or from the left of the middle determined by longitudinal axis of upper stamp (9) lowering in incrementally formed metal sheet (3), minor forming as compared to other stages of bending is performed. Then under impact of relative closing force (F) acting persistently outside on out-of-round blank mould (13) correspondingly on previously less formed sections (12a, 12b) on both sides from the middle formed is a ready pipe (104) with butt weld. The device is equipped correspondingly.

EFFECT: reducing risk of pipe deformation.

7 cl, 4 dwg

Description

The invention relates to a method for manufacturing pipes with a butt seam from metal sheets, in particular, from thick metal sheets, in which the metal sheet is fed to a pipe forming press, in which it, lying on the lower die, is raised and lowered by the upper die under the action of force the bends are progressively formed into a pipe with a butt weld having opposite longitudinal edges with a gap for subsequent longitudinal weld. In addition, the invention relates to a device for implementing the method.

A method of forming pipes with progressive stages of molding, or bending, relates to a practical method for manufacturing pipes from sheets of metal. The tube-forming, or tube-bending, press in the main frame usually has a lower die, consisting of two supporting, or bending, bodies installed next to the side gap, and mounted vertically on top of the lower die, held by a raised and lower bending console and running along the entire length of the metal the sheet is the upper stamp, with which the bending force can act on the metal sheet located on the lower stamp.

For the manufacture of pipes, or pipes of large diameter, progressive molding requires several consecutive stages of production. At the first stage, the metal sheet is pre-bent along the longitudinal edges, usually in a separate press brake. Preliminary bending of the longitudinal edges is carried out so that the radius of the pipe during molding into a pipe with a butt weld in the area of the future weld where the longitudinal edges of the metal sheet bent into the pipe are located opposite each other with a gap is uniformly formed. Then the pipe, preformed in this way, is inserted into the pipe forming press and there it undergoes the actual bending process. In this case, as a result of pressing the upper stamp on the metal sheet, a bending force acts, and under the action of the bending console and the upper stamp held by it, the forming of the metal sheet is regulated. This process is repeated many times until the metal sheet is molded into a pipe with a butt weld.

From DE4215807C2 a tube bending or tube forming press became known as a frame structure. The bending console, made as a bending stamp, is vertically guided in the side racks of the frame. This upper bending stamp on the piston-cylinder blocks is to some extent fixed with cardan mobility and with their help rests on the upper cross member of the frame. The supports of the lower bending stamp are held by a table, which also supports the piston-cylinder blocks, acting coaxially with the upper piston-cylinder blocks. Blocks of the piston cylinder, opposing each other, must prevent the deflection of the table, even if the lower cross member of the frame bends under the action of the working load of the press. For this, individual piston-cylinder blocks are subjected to pressure to a greater or lesser extent.

The large residual joint gap of the order of 130-170 mm, which is significantly affected by the width of the cantilever, in particular in the case of thick-walled pipes, for example, 40 mm, and, in addition, the stress in the pipe with a butt weld, proved to be very problematic with the progressive molding method. A large joint width requires large closing forces in the tack welder, and due to the large stresses in the stuck pipe, as well as residual stresses in the welded pipe, there is a risk of rupture of the stuck, or welded, seam. If too large a joint is found, experienced machine operators come to the rescue, who, by re-manually starting the tube forming press, close the joint as much as possible. This method of action can be carried out not only with large losses of time with a corresponding reduction in productivity, but also, with the loss of reproducibility of good quality.

Therefore, the basis of the invention is the creation of a method and installation of the aforementioned type without the above drawbacks, in particular, the simple manufacture of round cylindrical pipes with a butt weld even in the case of thick-walled pipes of small diameter, for example, of the order of 800 mm, with reproducible quality.

This problem is solved by the method according to the invention in such a way that a pipe with a butt joint of a non-circular draft form is first formed, for which, at least at one bending step, it acts on the inner side of the metal sheet, respectively, left and right relative to the middle defined by the longitudinal axis upper stamp, immersed in a progressively formed metal sheet, carry out less molding compared with other stages of bending and that after that under the action of the closing force, purposefully de stvuyuschego outside of the non-circular parison respectively less than the previously molded portions on both sides of the middle otformovyvayut finished pipe with butt weld.

When a non-circular rough mold made in size is consciously molded in such a way with less molded sections, for example, flexible at 12 ° instead of 24 °, the round geometry of the pipe with a butt joint with a minimum clearance is largely molded. Namely, thanks to less formed sections, a condition is created so that the closing force acting outside then and on these less formed sections acts clearly more than in other sections of the pipe, and as a result, a substantially round pipe with a butt weld with a desired closable gap is produced . In contrast to the dependence on the experience of machine operators, with constant quality, both reproducibility and productivity are improved.

Both for partial non-circular and for final or final molding, two bending steps or two forging processes may be sufficient, namely, even the closing force acting with the corresponding final molding to the left and right of the gap or joint.

A preferred measure according to the invention provides that the non-circular draft form is positioned prior to being subjected to the closing force by rotating clockwise or counterclockwise. Thus, depending on the positioning, the closing force is applied to a non-circular preliminary form near the joint, or gap, to the left or right of it.

According to a preferred proposal of the invention, the less-formed portion to the right of the middle rotates to a position of approximately three hours, and the less-formed portion to the left of the middle rotates to a position of approximately nine hours. With this pre-positioned non-circular position on the supports of the lower die, the maximum bending moment for the final molding is achieved.

The task underlying the invention is solved by using the device due to the fact that for deformation of the metal sheet into a non-circular draft form, and then a lower stamp is provided in the pipe with a butt weld, made with means configured to change its direction of rotation, and punch acting on the positioned draft form from the outside.

Thus, a finished pipe with a butt weld, starting from a metal sheet, can be manufactured only on one tube-forming press, or tube-forming machine. At the same time, a change in the direction of movement allows the non-circular draft shape to be so accurately positioned that the closing force appears at the event site, namely, on both sides of the joint. In this case, the bending console of the tube forming press can also be used simultaneously to exert a closing force on the rough form from the outside. As an option, the press can be converted into a punch for forging.

A preferred embodiment of the invention to increase production provides that at least one non-circular draft molding press is connected in series with a closing press which comprises a lower die with means configured to change its direction of rotation, and as the upper stamp punch acting on a positioned non-circular draft form from the outside. Thus, during the production process, a press for closing is connected to the pipe forming press from which the non-circular shape is released, in which the submitted non-circular draft form is at least in two successive stages, respectively, to the right and left of the joint or gap, close to it is deformed into a finished pipe with a butt weld. Thus, the rough forming of the metal sheet can be carried out in a place independent of the final molding of the pipe with a butt weld.

The rotation means of the lower die according to the proposal of the invention are made in the form of two driven in rotation of the rollers located at a distance from each other. Changing the direction of rotation of the rollers allows you to position a non-circular rough mold for final molding with the application of optimized force. The time of forming in the pipe forming press, on the one hand, and final production in the press for closing, on the other hand, allows the series-connected press for closing to serve two pipe forming presses.

One of the embodiments of the invention provides for the rotating rollers to be mounted with a suspension. The support of the draft form on the lower die of the press for closing should be improved due to the stationary support provided between the rollers.

Other features and details of the invention arise from the claims and the following description of an example embodiment of the invention depicted in the drawings, based on two separate presses. Wherein

Figure 1 depicts a schematic stepwise molding (a) of a metal sheet into a pipe with a butt weld (b) on a pipe forming press related to the prior art, and a finished pipe with a butt weld in the diagram (c) for a given example with size;

Figure 2 - schematically the manufacture of a pipe with a butt weld according to the invention by prefabrication of a non-circular draft shape in size on a conventional tube forming press (a), the final manufacture of a pipe with a butt weld of a non-circular draft form on the press (b) to effect closure connected in series to a pipe forming press, and a finished pipe made according to the invention with a butt weld (c) in a size chart, as shown above in FIG. 1;

Figure 3 - press for closing with installed in it non-circular draft form as a part in figure 2, and

4A, 4B are a schematic diagram of the final molding or processing of a non-circular draft form from a tube forming press by pressure in at least two stages of bending on a press to effect closure, namely, in the first stage of bending with the application of force to a non-circular draft form near the joint, or a gap (Fig. 4A), to his right, and after turning a non-circular draft form in the second bending step with the application of force near the joint, or a gap (Fig. 4B), to his left.

On a sufficiently well-known pipe forming press 1 in Fig. 1, a metal sheet 3 with bends 2 (see Fig. 3) of the edges on its longitudinal sides is gradually formed, or deformed, into a finished pipe 4 with a butt weld. In this case, the metal sheet is laid on the lower die 6, which has two supports 5a, 5b located at a distance from each other, and the deformation force is created by the upper and lower upper dies, made in the form of a bending console 7 with molding tool 8 mounted on its leading front end. The molded, or deformable, metal sheet 3 is guided by two lateral counter supports 10a, 10b, of which the counter support 10a moves linearly and feeds a portion of the sheet necessary for the next forming step. The finished pipe 4 with a butt weld, shown in figs, has a large joint or gap 11, which makes it extremely difficult to weld a closed longitudinal welded pipe, shown in figure 1 with a dashed line.

The forming of the metal sheet 3 into a pipe 104 with a butt weld having a significantly smaller joint or gap 11 (see FIG. 2c) is carried out according to FIG. 2a on a pipe forming press 1 similar to that described above. However, this happens with the condition that in the corresponding section, located to the right and left of the longitudinal axis of the bending console 7 and thereby near the junction or gap 11 of the metal sheet, the bending step is carried out with less bending of the metal sheet than in other bending stages. Thus, in accordance with the bending step, two less-formed portions shown in FIG. 3 are definitely obtained, so that a non-circular, although for the final forming, size-made rough mold 13 is purposefully achieved.

The draft form 13 obtained in the pipe forming press 1 in the first stage, after issuing, or pushing out, from the pipe forming press 1 is fed into the press 14 connected in series during manufacturing to close, shown in 2b. Press 14 for closing includes a lower stamp 15, consisting of two rollers 16a, 16b provided at a distance from each other, driven into rotation and changing their direction of rotation, as shown in FIG. 2b by double arrows, and from overlapping the gap between the rollers 16a , 16b of the stationary support 17. The rotating rollers 16a, 16b can be mounted using spring means (see FIG. 3). Opposite the lower die 15, an upper die 20 is installed, made with a punch 19. With the help of the punch 19, a closing force is created to produce a finished, largely round pipe with a butt weld 10, acting on the non-circular draft form 13 from the outside.

For this, the non-circular draft form 13 is positioned by means of the rotating rollers 16a, 16b so that the less-formed portion 12b located next to the joint or gap 11 on the right is in the three-hour position, as shown in FIG. 3 by the horizontal dash-dotted line line.

The course of this first bending step for closing is depicted in FIG. 4A from left to right with a non-circular draft form 13, the action of the closing force with the punch 19 and the punch 19 retracted after the application of force.

The second closing step in the same sequence as above is shown in FIG. To optimize the bending moment, here in the left half the invariably non-circular draft form 13 is positioned in such a way that the less-formed portion 12a located next to the joint or gap 11 on the left is in the nine o'clock position. Now, the closing force A (central image), applied with the punch 19 on this side of the draft form 13, in this case, leads the non-circular draft form 13 to the final, largely circular shape of the finished pipe 104 with a butt weld with an obviously smaller joint , or clearance, 111 (image on the right).

LIST OF POSITIONS

1 pipe forming press

2 edge bending

3 metal sheet

four; 104 butt welded pipe

5a, b support

6 bottom stamp

7 bending console

8 molding tool

9 top stamp (punch)

10a, b counter support

11, 111 butt / gap

12a, b less formed sections

13 non-circular shape

14 press for closing

15 bottom stamp

16a, b rotating rollers

17 prop

18 spring tool

19 punch

20 top stamp

F closing force

Claims (7)

1. A method of manufacturing pipes (4; 104) with a butt seam from metal sheets (3), in particular from thick metal sheets, comprising supplying a metal sheet to a pipe forming press (1), in which it is placed on the lower die (6), with the help of a raised and lowered upper stamp (9), under the action of a bending force, they are progressively formed into a pipe (4; 104) with a butt weld having opposite longitudinal edges with a gap (11; 111) for subsequent longitudinal welding, characterized in that it is first formed butt weld pipe non-circular the second draft form (13) by performing less molding at least one bending step compared to other bending steps on the inner side of the metal sheet (3), in areas, respectively, left and right relative to the middle defined by the longitudinal axis of the upper stamp (9 ), immersed in a progressively molded metal sheet (3), after which the force (F) of closing a non-circular draft form (13), deliberately acting externally on previously less formed sections (12a, 12b) on both sides of the sulfur ins, otformovyvayut finished tube (104) with a butt seam. 2. The method according to claim 1, characterized in that the non-circular draft form (13) at the manufacturing stage before the action of the force (F) of the closure is positioned by rotating clockwise or counterclockwise. 3. The method according to claim 2, characterized in that the less-formed portion (12b) to the right of the middle is rotated to a position of about three hours, and the less-formed portion (12a) to the left of the middle is turned to a position of about nine hours. 4. A device for the manufacture of pipes (4; 104) with a butt weld of metal sheets (3), in particular of thick metal sheets, in particular, by the method according to claim 1, containing a pipe forming press (1), in which the metal sheet with an arrangement it on the lower die (6) with the help of a raised and lowered upper die (9) under the action of bending forces is progressively formed into a pipe (4; 104) with a butt weld having opposite longitudinal edges with a gap (11; 111) for subsequent longitudinal welding, characterized in that for the deformation of met of the metal sheet (3) into a non-circular draft form (13), followed by deformation into a round pipe (104) with a butt weld, it has a lower die (15) with draft positioning means rotatable with a change in the direction of rotation, and a punch (19 ) acting on the positioned draft form (13) from the outside. 5. The device according to claim 4, characterized in that after at least one tube forming press (1) for the manufacture of a non-circular draft form (13), a press (14) is installed for closing it, comprising a lower die (15) with draft positioning means forms made with the possibility of rotation with a change in the direction of rotation, and as the upper stamp (20) - a punch acting on the positioned non-circular draft form (13) from the outside. 6. The device according to claim 4 or 5, characterized in that the lower stamp (15) contains two driven in rotation of the roller (16A, 16b), located at a distance from each other, and a support (17) between the rollers (16A, 16b) . 7. The device according to claim 6, characterized in that the rollers (16a, 16b) are installed using spring means (18).

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