SE413477B - EXPANDABLE DORN FOR USE IN BUILDING OF Pipes - Google Patents

Description

7809371-3 10 15 20 25 30 35 2 With an outer diameter of 500 mm, the rubber sleeve may have one undeformed diameter of eg 480 mm) and which is therefore Assemble the plastic sleeve so that the slot in it closes. Ef- mounting the plastic sleeve with the rubber sleeve attached a carrier having a mandrel expansion device in the form of an outer or several successively placed, outer, inflatable blisters, so-called volcanic blisters, can be the expansion device expands the slotted plastic sleeve to its original construction diameter (ie 500 mm at that as an example mentioned case). The outer rubber sleeve, which serves as a mandrel contraction device, will in this case, of course, to be under tensile stress. On the so- The expanded mandrel can be used to build tubular products. such as reinforced plastic pipes. After the manufacture of the tubular products, relieves the pressure on the vulvar bladder or blisters, the rubber sleeve being pressed together. the torn plastic sleeve until the slot is closed.

Then the mandrel can be easily pulled out of the tubular the product.

The invention will be described in the following with reference to display to the accompanying drawing. Fig. 1 shows a diagram longitudinal section through an expandable mandrel according to the present invention. Fig. 2 shows a section along the line II-II in Fig. 1. Fig. 3 shows a portion of a section through another embodiment.

The exemplary embodiment of the mandrel according to the invention has a plastic sleeve 10, which is made of reinforced thermosetting plastic, eg polyester. A longitudinal section of the plastic sleeve has then been sawn off to form one longitudinal slit ll. The outside of the plastic sleeve has a rubber sleeve 12 heeled. The rubber sleeve 12, in its undeformed able to have a smaller inner diameter than the plastic sleeve to be able to compress the plastic sleeve, so that the slot ll is closed.

The plastic sleeve and the rubber sleeve are placed on a mandrel carrier 13, on which a number of successively placed expanders only rubber bladders 14 are mounted. The rubber blisters are retained using hose clamps 15. The rubber bladders can be fed with compressed air via separate compressed air inlets 16, which open into a 10 15 20 25 30 35 7809371-3 3 distribution chamber 17 inside each rubber bladder. Rubber blue the sores support the slotted plastic sleeve and serve to enable its expansion to its original, outer diameter given during manufacture, eg 500 mm. At relief of the pressure in the expandable rubber blisters more the outer rubber sleeve 12 to compress the torn said the plastic sleeve, so that the slit ll be closed. The mandrel carrier 13 also has end flanges 18, which serve as end molds at the construction of a tubular product on top of the expander just the thorn. These ends are removable and are attached on the mandrel carrier in a manner not further shown. On the end flange There are retaining rings 19 which, in the embodiment shown, the exemplary ring are located outside the plastic sleeve 10 and the rubber the sleeve 12 but which may also be located inside them.

These rings 19 serve to center the door, as often need to be rotated in the construction of the tubular products terna.

A great advantage of the mandrel construction according to the invention The solution is to cut through a plastic sleeve given the opportunity to achieve an expanded mandrel, which has a true cylindrical shape, which does not apply if one were to have manufactured the plastic sleeve with a larger diameter than the inner diameter the meter of the tubular product to be manufactured, and if you then sawed a longitudinal saw cut in this plastic sleeve to enable the plastic sleeve to bend so that the portions of the plastic sleeve on either side of the saw would overlap as shown "i DT-AS l 128 797.

As shown in Fig. 3, even with a mandrel according to the invention have a certain overlap, but in this case tea one first manufacture the slotted plastic sleeve on it the above method by removing a eg 30 mm wide section and then afterwards attach an overlapping tongue 20 on risk one side of the slot. In order for the true cylinder the shape of the plastic sleeve must not be spoiled, must however, this overlap tongue should be very thin and be recessed on one side of the slot, the plastic sleeve 10 and the tongue 20 is chamfered on the other side of the slot 11, 7809371-3 4 so that the tongue follows the cylindrical outside of the slotted plastic sleeve.

Claims (1)

Claimed mandrel for use in the construction of pipes, consisting of a pipe sleeve (10), a mandrel contraction device (12) surrounding it and a mandrel expansion device (14) arranged in the pipe sleeve, characterized in that that the pipe sleeve (10) consists of a rigid but flexible material and is manufactured in such a size that, when the mandrel is expanded to the inner shape of the future pipe, it assumes its undeformed size, given during manufacture, and that the pipe sleeve has a longitudinal slot (II), which allows contraction of the pipe sleeve for pulling the mandrel out of the built-up pipe. 2. A mandrel according to claim 1 for the construction of cylindrical tubes, characterized in that the mandrel, when the tube sleeve (10) is in an undeformed state, has the same diameter as the interior of the future tube. A mandrel according to claim 1 or 2, characterized in that the tube sleeve (10) has a post-slit for forming the longitudinal slot (II) (20), which is recessed to follow the shape of the plastic sleeve, when it takes over its ode- k e nn e-shaped form.