DE1196847B - Mandrel-like tool for bending pipes made of thermoplastic material - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. α .:

B 29 c

German class: 39 a2- 17/02

Number: 1196 847

File number: E 21966 X / 39 a2

Filing date: November 15, 1961

Opening day: July 15, 1965

The invention relates to a mandrel-like electrically heatable tool for bending pipes made of thermoplastic material, the mandrel made of soft material, e.g. rubber and an outer diameter of the same order of magnitude as the inner diameter of the to having bending tube.

The basic technique when bending pipes made of thermoplastic material, in particular made of plasticizer-free polyvinyl chloride, consists in the fact that the pipe to be bent is just like in the treatment of steel pipes with sand filling. The PVC pipe to be bent is closed from the one side and fill it with sand, preferably warmed sand, from the other side. Then press you get the sand together by tapping the outside of the pipe with a hammer. the the other side of the tube is closed with a wooden stopper that is wrapped in a strip of fabric is. Various designers close the pipe with a welded-on bottom in order to prevent the plug from loosening when the plastic material softens. The tube is heated weak flame, as the plastic material is a very poor conductor of heat, or it is heated in an oven to 120 to 130 ° C. As soon as the plastic material has softened sufficiently, the PVC pipe is bent about a lesson. After the curved pipe has cooled down, the sand is removed.

This is the most widely used method to this day. It is very cumbersome and conditional difficulties; because a pipe with a diameter of 90mm e.g. requires two operators and half an hour for filling in and tamping the sand as well as one half an hour dwell in an oven at a temperature of 130 ° C. The softened plastic Pipe is because of its weight and because of the lack of stability of the sand as well as because of difficult to handle due to the high temperature. The diameter of the pipe cannot be 150 mm if the weight of the sand is not intended to cause the pipe to flatten. The tamping of the sand must be perfect, if not the inside of the curve of the PVC pipe Obtain an oval shape and have folds. It is also necessary to use the pipe to be completely filled with sand so that not only part of the pipe is bent.

One known working method is to use a coil spring made of steel wire. The coil spring is inserted into the pipe to be bent. A mandrel-like tool for bending pipes
made of thermoplastic material

Applicant:
ίο Georges Enghels, Gand (Belgium)

Representative:

Dipl.-Ing. G. Schmitz-Helff, patent attorney,
_lg Köm, Hohenzollernring 84

Named as inventor:

Georges Enghels, Gand (Belgium)

Claimed priority:

Netherlands November 19, 1960 (258155)

and removes the spring from the curved pipe after it has been bent and cooled.

This mode of operation has the significant disadvantage that the turns of the helical spring in the plastic After being bent. On the other hand, it is sometimes impossible to Remove the coil spring from the curved tube after it has cooled down.

A known device, which is based on the same working principle, consists of a resiliently expandable and flexible hollow body formed by the interweaving of elastic metallic bands and the one slightly larger diameter than the inner diameter of the pipe to be bent owns. To insert this hollow body into the interior of the pipe to be bent and to pull it out again, you have to pull on the eyelets attached to the ends of the hollow body so that the metallic Bands approach each other and thereby the diameter of the hollow body is reduced. This device also has the disadvantage that the inner surface of the to be curved Rohres comes into firm contact with the metal bands, which have the endeavor during their Heating into the soft material of the tube

509 600/387

Claims (2)

3 4 to penetrate. In addition, the hollow body can easily get pers2 through the pipe. In the body 2 be damaged, especially because the elastic is embedded in an electrical resistor 3 that is connected to Tapes through the train for their introduction and their the terminals 4 for entry and exit of the elec- Distance in the curved part of the pipe heavily Irish current by means of insulated cable 5 claimed will. 5 is closed, which is connected to the outer ends 6 of the An improvement of the above-described body 2 with the interposition of metal equipment consists of a coil spring with pieces 7, which are also embedded in the spiral 2 a tube made of synthetic rubber are connected. Rings 8 made of insulating material is. In this known proposal that will support the cables 5 and are used for insertion and Rubber tube after it is abundant with talc io for pulling the body 2 in and out of the is rubbed into the plastic tube to be bent tube 1. The outer ends 6 of the body 2 are inserted and from the curved tube after the also crimped by a reinforcement 9 from Cold removed. The disadvantage of this method of working canvas is reinforced. is that the tube has a slightly smaller After inserting the heating coil into the must have outer diameter than the inner 15 bending tube 1 made of PVC is the electrical current Diameter of the plastic pipe after the bend is switched on and the pipe is heated until it is mung. In addition, the rubber tube will assume a temperature of 120 to 130 ° C, a because of the elongation of the coil spring from the temperature at which the polyvinyl chloride steel during the withdrawal from the curved formable. It is noted that the heating coil th pipe quickly destroyed. 20 made of rubber based on silicone readily All these known means of bending a pipe can withstand a temperature of 318 ° C, resulting in a pipe using a bending device which results in a large safety range. According to the same way, a means for heating the pipe, softening of the pipe 1, the electric current is provided before it becomes plastic, the heating circuit is also opened and the pipe is bent around a jig arranged outside the pipe. The pipe is subject to the increased temw with this heating means either in the form of a temperature long enough, since the body does not have a heated coating, which is removed from the pipe in the course of the ocular heat exchange to the outside view of the curvature of the latter and maintains the heat effect. The body 2 must, or in the form of a heated spiral, is then withdrawn after disengagement from the bent tube which surrounds the tube, with the risk of cooling, the withdrawal being due to the fact that it is from the tube at the moment the great elasticity, which cannot be removed from the silicone curvature and which is inherent in rubber, is easy to do,
pushes the material of the pipe into it. In addition to the fact that the pipe is difficult to handle, one has the further disadvantage that the pipe is bent in a minimum of time, about 10 minutes, without the pipe having to be carried out very quickly if one turns to an external heating means, e.g. B. does not want to run the risk of a furnace that the pipe has to grab quickly from or a weak flame. It is hardened anew. In addition to these disadvantages, the facilities that are known even at the construction site are unwieldy because they allow the pipes to be bent from a thermoplastic plant heating device independently of the actual material. You can also use the Heilichen bending device. the pipe on the part to be bent The invention has the purpose of limiting the disadvantages, the remaining part of the pipe being cold to avoid the known bending devices, remains. It is evident that the method according to which she proposes a single element that allows the invention not only with regard to the hand, heating or softening and operation at the same time, but also with regard to emergency To realize bending of the pipes, and the manoeuvrable fixed devices for bending of raw use An external heating means made of thermoplastic material is not necessary and is very economical power. For this purpose the thorn is borrowed. from a strand-shaped body in which a The invention is by no means limited to the above electrical heating, e.g. a heating coil, is limited to an embodiment described, because it is bedded. deviations can also be carried out, According to a particularly advantageous embodiment, without departing from the scope of the invention, form of the invention consists of the strand-shaped body So the heating coil could also be made of synthetic per made of silicone rubber. Be made of rubber. This does not tolerate the Other details and peculiarities of the er- 55 high temperatures such as the rubber based Findings result from the following list of silicones, but its price is essential Writing of an embodiment, which is lower, with the advantage of using The silicone rubber is not limited to the drawing shown, especially in small diameters and which lies a partially broken section of a knife of the tubes to be bent, while for strand-shaped body according to the invention represents 60 tubes of larger diameter synthetic caustic, which is inserted into a pipe to be bent. Tschuk is recommended. According to the invention, in the interior of a too
bending tube 1 made of polyvinyl chloride without plasticizer (PVC) by pulling the strand-like claims:
Body 2 made of silicone rubber is introduced. The 63 The diameter of the body 2 is a little larger than 1. A mandrel-like, electrically heated tool the inner diameter of the pipe 1 to be bent, for bending thermoplastic pipes such that an effective compression of the body material, the mandrel made of soft material, e.g. rubber, and have an outer diameter of the same order of magnitude as the inner diameter of the pipe to be bent has, characterized in, that the mandrel consists of a strand-shaped body in which an electrical heating means, z. B. a heating coil is embedded. 2. mandrel-like tool according to claim 1, characterized in that the strand-shaped Body is made from silicone rubber. Documents considered: German Patent No. 960 046; U.S. Patent No. 1 602165. 1 sheet of drawings