TOOL FOR BENDING A PIPE

The present invention relates to a tool for bending a pipe, which tool includes an operating device, at least one guide and a moving slide therein, two opposing dies, installed on a different plane relative to the movement of the slide, one of which is installed on the said slide to be moved on the guide and driven by the operating device, and the second fixed immovably to the guide, and, when the straight pipe, placed between the dies set in the open position, is arranged to be bent into the shape determined by the dies by pressing them towards each other using the operating device.

In industry, various pipe runs are installed for pneumatic, hydraulic, and lubrication systems. When the points of use lie in the same direction, the pipes are usually installed next to each other to form a neat bank of pipes . Particularly in connection with device replacements, pipe extensions must be made using pipe connectors that can in no way be made to fit inside the pipe bank, but instead the pipe equipped with an extension must be equipped with a so-called offset connector, i.e. the pipe must be bent outwards from the plane of the pipe bank. Two consecutive bends are required, by means of which the end of the pipe is moved outwards from the plane of the pipe bank, while remaining parallel to it. If such connections are also required in adjacent pipes, they are generally made by overlapping three pipe extensions longitudinally at a distance to each other, so that the fourth pipe extension can once again be parallel to the first.

Publication WO 00/47345 discloses a pipe-bending tool according to the preamble, which is especially intended for making pipe offsets on site. In asymmetrical bending, a strong guide is needed to control the die, because large lateral forces arise during bending and the die that moves at different levels and the die, which moves on different planes, also creates bending

in a plane at right angles, by means of a power arm between the planes of movement. This publication presented, for the first time, a die arrangement installed on a different level to the slide and the stroke of the operating device.

Conventional symmetrical pipe bending, on the other hand, does not require a separate die guide, but instead the bending itself can centre the die, as disclosed in publications US 4,055,069. US 4,232,542, and US 2,867,261. In this case, the only lateral control is obtained from the piston rod, which can, however, easily be subject to excessive stress, if the compression is asymmetrical for some reason. Other corresponding tools are disclosed in patent publications US 5,105,646 and US 5,643,139. In these, the die moves always at the end of the piston rod, and thus on the same plane as the centre line of the operating device. In these, however, the asymmetry of the support structure creates bending at right angles to the bending of the pipe.

Further, the bending tool known from the aforementioned WO publication becomes quite heavy, making it difficult to use, even though it facilitates the manufacture of an offset connection on site.

The present invention is intended to create a pipe bending tool that is simpler and lighter than previously, which can be used versatilely in different kinds of pipe-bending work. The characteristic features of the pipe-bending tool according to the invention are stated in Claim 1. The tubular guide according to the invention, which is preferably manufactured from aluminium profile, is structurally strong and torsionally rigid. This overcomes both the compression taking place in different planes relative to the pushing and the possible bending stresses created by the asymmetrical die construction. The number of components in the tool is small and their unit weight is light in all size classes.

According to one of the most preferred embodiments of the invention, a battery-powered hydraulic-cylinder pump mechanism, which is attached directly to one end of the tubular guide, is used as the operating device.

The tool according to the invention can be applied quite diversely. In addition to the aforementioned pipe offset bending machine and general pipe bending, other applications include cutting devices and compressing-ring installation devices (e.g., ERMETO® compressing-ring joint).

Other embodiments and benefits of the invention will become apparent in connection with the following examples of applications, which are shown in the accompanying drawings.

Figure 1 shows an axonometric view of the pipe-bending tool according to the invention, without the operating device,

Figure 2 shows a top view of the tool of Figure 1, Figure 3 shows an end view of the tool of Figure 1, without the retainer, Figures 4a and 4b show cross-sections of the tool, in the open and closed positions,

Figure 5 shows the guard-plate arrangement of the tool, Figure 6 shows an axonometric view of one prototype of the tool.

The main components of the tool according to Figures 1 - 3 are a tubular guide 14, in which there is a widened support surface 14.1 on the unified upper surface of a fin component 14.2, on top of which the first die 13 moves. The second die 12 is fitted permanently to the end of the guide 14. In the known manner, in the dies 12 and 13 there are shaped parts to receive the pipe. The dies can be changed and generally the tool in- eludes a die series for pipe of different sizes, as well as special dies for the said offset. The width of the widened

support surface 14.1 is 2,5 times that of the tubular component while the fin component 14.2 thins towards the edges (Figure 3) .

5 A retainer 11 is drawn in Figure 1, but is not shown in the other figures. The retainer 11 allows the device to be secured in, for example, a vice (not shown) .

The slide mechanism is entirely inside the guide 14. Its con-

10 struction is apparent from Figures 4a (open position) and 4b

(closed position). Only the attachment collar 30, which is attached by a screw thread in the guide 14, of the operating device is visible. The actual cylinder 17 of the operating device extends from inside the attachment collar 30 into the

15 guide 14. This corresponds to the lock ring 24 inside the tubular guide. Inside the cylinder 17 moves a piston 19, the rod 18 of which presses on a slide 15, which itself is a piston component moving inside the tubular guide. At one end of the slide 15, there is a cylindrical drill hole 15.1, which pro-

20 vides space for a return spring 27. The other end of this spring is supported by the fixed end piece 25, in which there is a pin 25.1 for guiding the spring.

The fixed die 12 is attached, with the aid of a pin 12.1, to 25 the end of the guide 14, the pin also penetrating the end piece 25. In the fixed die 12, there is an end flange 12.2, which prevents it from rotating relative to the pin 12.1. The moving die 13 is fixed to the slide 15 with the aid of the pin 13.1. In order to permit the stroke of the pin 13.1, there is a gap 30 20 in the guide 14, through which gap the pin 13.1 connects the internal slide 15 of the guide and the external die 13 to each other. The tubular construction of the guide 14 is weakened by the gap 20, but this weakening is entirely compensated by the wide fin component 14.2.

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The pins 12.1 and 13.1 can be manufactured according to stan-

dards DIN 6325 or DIN 7979. They can be equipped with a quick-locking element, for example, a wing nut, or a spring-loaded ball, which can also be in the die itself. On the guide 14 side, an interference fit can be advantageously used in the attachment of the pin 12.1, 13.1.

Because the gap 20 represents a safety and fault risk when it is open, it is covered by a guard-plate mechanism, which is shown in the exploded drawing in Figure 5. (The drill hole in the guide 14 of the pin 12.1 of the die 12 is not drawn in the figure.) The pin 13.1 of the fixed die 13 moves the thin cover plate 22, in which there is a wide opening 22.1. The cover plate 22, for which there is a shallow groove 23 in the support surface 14.1 of the guide 14, is covered by a unified thin top plate 21, in which there is a gap 20.1 (corresponding fully to the gap 20) and an attachment lug 21.1. According to Figure 1, the top plate 21 is secured by attachment screws 29 and additionally by the threaded end 25 to the guide 14. The slight curve of the cover plate 23 and its path (groove 23) have been shown to be advantageous operationally.

In the prototype of Figure 6, the aforementioned guard-plate mechanism is not used and thus the gap 20 is visible. The battery-operated operating device 16 (e.g., Dubuis SA, France; model CG85 elect., or Gustav Klauke Gmbh, Germany; models ES85, ESG85PLUS, all without cable cutters) is attached with the aid of the threaded collar 30 to the tool 10, which can rotate relative to it to a limited extent.

The aforementioned battery-operated operating device creates a 55-kN force on a 32-mm diameter piston, which corresponds to a pressure of 680 bar. This is sufficient to bend quite thick pipes (diameter 30 mm) .

The guide 14 is most preferably manufactured from aluminium profile, which as a unified structure is strong and torsionally

rigid. The number of components is small, as is the unit weight.

In the above case, the operating device is only integrated in the tool to a small extent. In one variation, the end of the slide forms directly the piston of the hydraulic cylinder, in which case the oil chamber moves to the present location of the piston rod 18, compared to the situation in Figures 4a and 4b. This requires the moving die to be attached to the front part of the slide, with the aid of a suitable intermediate part parallel to the surface. This intermediate part can be installed in its own groove. The tool can be substantially shortened by means of such a construction.

It must be understood that the above description and the related figures are only intended to illustrate the present invention. The invention is thus in no way restricted to only the embodiments disclosed or stated in the Claims, but many different variations and adaptations of the invention, which are possible within the scope on the inventive idea defined in the accompanying Claims, will be obvious to one versed in the art.