FI109772B - Thin wall pipe bend prodn. - comprises use of two profiles in a blank which are mirror images to form a gutter and sepg. the gutter from the blank and dividing it into halves - Google Patents

Abstract

Prodn. of a thin walled pipe bend comprising (a) forming an annular gutter (2) in a blank (1) having a profile corresponding to one half section of the pipe each half bend being formed in a mirror image of another half, (b) parting the gutter from the blank, dividing it into the half pipes and joining the halves to form the pipe bends.

Description

109772

METHOD FOR MAKING A THIN WALL TUBE CURVE - SÄTT ATT FRAMSTÄLLA EN TUNNVÄGGIG RÖRKRÖK

The invention relates to a method for producing a thin-walled tube curve, comprising the steps of producing halves of a tube curve, wherein the halves are mirror images of one another with respect to the curvature surface of the tube curve, and two halves are joined together to form a tube curve.

In the past, it is known that thin-walled pipe curves 10 can be made in the above manner. The starting material is then in the form of a sheet metal strip which is cut into trapezoidal preforms alternately in the longitudinal direction of the strip. Each of these blanks is then used to make a half of the tube curve, where the halves are mirror images of each other, and it is therefore conceivable that the tube curve is distributed along its curvature surface. Two such halves are then joined together in a suitable manner, e.g. by welding.

20 There are many weaknesses in the known method, one of which is relatively large! the disposal of the substance by the fact that:. a crimping process is used to make the half-pipe curves, which requires relatively large amounts of material! 25 around the pre-formed pipe curve.

,; Another problem with the prior art method; "is that the preforms in the material strip are inverted flow *, so that every other preform must be treated separately in an additional step before it can be transferred to the press where the forming is performed.

The present invention relates to the aforementioned '. a manufacturing process which has been made to overcome the aforementioned drawbacks. The invention thus relates to a manufacturing process which, in particular, makes it possible to produce tube curves with an absolute minimum; paint with material consumption, possibly thinner material than previously possible and 109772 2 with minimal number of processing steps. The invention further relates to a process for producing a finished product of good quality and precise shape.

The object underlying the invention is achieved when the manufacturing method mentioned in the introduction is characterized in that an annular recess is formed in the sheet metal blank, which is formed with a profile substantially coincident with the half profile, and the recess is detached from the blank and divided 10 to form a plurality of halves.

In a preferred embodiment of the invention, it is also true that, when forming a groove, a hole is made in the blank inside the groove.

With these special features, the dimensions of the blank can be further reduced, since hole formation means that relatively more material is withdrawn from the area inside the groove when forming the groove than would be the case without the central hole.

The invention is also best characterized by leaving approximately radially oriented bridges which bind the parts of the blank outside the slot with those of the inside of the slot when dividing the slot.

I 25 These special features give the advantage, '' *! ; that the scrap material remaining in the manufacture when the ring is formed will remain in the size, which is why it is easier to handle.

- * · 30 The invention will now be described in detail with reference to the accompanying drawings in which [. Figure 1 is a plan view of a blank having a ring-shaped recess, and Figure 2 is a cross-sectional view of a groove; 35 as shown in Figure 1.

In its most common form, the invention! relates to the manufacture of halves from which the pipe curves are joined together, starting from a closed, annular groove having a profile or cross-sectional shape substantially the same as the half of the pipe curve. The recess, in turn, is made of pu-5 by crossing a substantially square or rectangular sheet metal blank that may be cut from a sheet or roll. By dividing the annular groove thus produced, a plurality of halves are provided which are joined together by two and two to form tube curves.

In the manufacture of a ring-shaped groove, the sheet metal blank 1, which is preferably of square or rectangular shape and which may be cut from rolled sheet metal, is started. The square blank avoids the need for alignment of the blank.

The preformed blank 1 is introduced into a press device where it is formed into a recess 2 which is annular and has a cross-sectional shape which is preferably semicircular (if the tube curve shape 20 is to be an annular cross section) but which can of course be of any suitable shape. Figure 1 shows that the groove 2 in the embodiment shown consists of four annularly curved portions 3, which are connected in pairs by straight portions 4. Making a notch is made by applying essentially the conventional punching method so that a scrap piece 5 is formed on the outside of the notch 2. In the same way, a piece 6 is formed on the inside of the notch. the scrap list 5 and the scrap section 6 are mainly in the common plane and that the groove 2 is located completely on the other side of this plane.

In order to reduce the width of the required external scrap strip 5, during the pressing process, preferably 357, the final hole is cut into the central scrap portion 6 of the blank 1 when the diameter of the finished pipe curve should be 120 mm. there is about 25 mm left in the tool stroke, i.e. when about 40% of the work stroke is left.

By using this central opening 7 5, the great advantage is obtained that the blank which, during the pressing operation, forms a wall in the groove 2 is taken to a greater extent from the central part of the blank than from the outside to the outside. In this way the dimensions of the blank 1 can be reduced so that the total material consumption 10 is further reduced accordingly.

Once the recess 2 is formed and the blank 1 thus has the shape shown in Figures 1 and 2, the recess itself is cut off from the additional portions 15 of the blank 1 (i.e. scrap sheet 5 and scrap section 6). In addition, the closed annular groove is divided into a number of halves, four pieces in Figure 1, which are then joined together by two and two, e.g. by welding, to obtain a complete tube curve.

When the groove 2 is divided, cut along the dotted lines 8 so as to form narrow material bridges which bond together with the scrap part 6 in the middle of the outer scrap strip 5. This keeps the scrap in the blank. , which makes it easier to handle.

· 25 The material savings achieved by the invention according to the invention are with a pipe diameter of 120 mm.

: 15% compared to the known / / · manufacturing method described above in the introduction using a semi-directional preform. When the indentation occurs completely symmetrically, the thickness of the material in the blank used can probably be slightly reduced, possibly in the order of 10 to 20%, further saving the material without risking any disadvantages.

35 It has been required above that the pipe curves are intended to extend round cylindrical pipes, so that the half sections of the pipe curves and 109772 5 turns have half-cross sections or profiles! pyröitä. However, according to the invention this is not necessary, but the profile shape of the groove 2 can be adapted to each sectional shape of the intended pipe curve.

In addition, of course, the length of the straight sections 4 in the groove can be varied within wide limits depending on the final shape of the intended pipe curve. In one extreme case, the straight parts 4 may possibly be completely omitted. In addition, the straight parts need not be equally long at each end of the half.

According to the invention, it is also possible to produce pipe curves having different diameters at each end. According to the invention, it is only required that the annular recess 15 be given a corresponding shape such that it has a greater radial dimension at every other intersection 8 than is the case at the other intersections. In one embodiment, as shown in Fig. 1, the radial dimension in the image at the upper and lower 20 intersections 8 could e.g. be 160 mm (thus the profile is a semicircle with a radius of 80 mm) while the radial dimension at both horizontal intersections could be 120 mm (profile, i. semicircle with a radius of 60 mm). Thus, such a dimensioning · · · 25 would result in a transfer tube curve from 120mm to 160 ’·’ ’mm φ.

i.i: Figure 1 requires that the pipe curve • ·: / ·· be 90 °, which is why four halves are made in one and the same tire. However, according to the invention, other angles of curvature for pipe curves can be easily made by dividing the annular groove into a number of parts other than those shown in the drawing. Thus, for example, the groove can be divided into only two parts, which would result in a single U-shaped pipe curve. 35 In the same way, the recess can be divided at three points which would result in a pipe curve having a curvature angle of 120 °. Similarly, pipe curve 109772 6 may also be divided into larger portions than shown in the figures.

Further applications may be made within the scope of the appended claims.

5

Claims (3)

7 109772 A method for producing a thin-walled pipe curve, comprising the steps of producing 5 halves of a pipe curve, whereby the two halves are mirrored to the curvature surface of the pipe curve and the two halves are joined together to form a pipe curve forming a profile which is substantially coincident with one of the half profiles and detaching the recess (2) from the blank (1) and dividing it to form a plurality of halves. Method according to Claim 1, characterized in that in the formation of the groove (2) a hole (7) is made in the blank (1) on the inside of the groove. Method according to claim 1 or 2, characterized in that, when dividing the slots (2) 20, approximately radially oriented bridges are left which bind together the blank parts (5) outside the slit (2) and the blank parts (6) inside the slit (2). with. i * * • »e 109772