WO2004110727A1

WO2004110727A1 - Method and system for forming a reducer for pipes

Info

Publication number: WO2004110727A1
Application number: PCT/FI2004/000369
Authority: WO
Inventors: Ajay Oommen
Original assignee: Oy Kwh Pipe Ab
Priority date: 2003-06-16
Filing date: 2004-06-16
Publication date: 2004-12-23
Also published as: FI20030898A; WO2004110727B1; MY138884A; FI117893B; RU2006101229A; FI20030898A0; CA2529483A1

Abstract

This invention concerns a method and a system for forming a reducer from a pipe of polymeric material, said method comprising the steps of : cutting the pipe to a required length; placing one end of the pipe onto the top of a conical mould member in a bath of a heating medium; heating said end of the pipe by the heating medium in the bath to a softening temperature of the polymeric material; applying a pressure to the other end of the pipe in order to push the pipe to a predetermined extent onto the mould member; and cooling the heated pipe when pushing is finished.

Description

METHOD AND SYSTEM FOR FORMING A REDUCER FOR PIPES

BACKGROUND OF THE INVENTION

This invention relates to a method and a system for forming a reducer from a pipe made of polymeric material. Formation of a reducer for a pipe by way of machining and jointing causes several known problems, for instance notch formation at the machined surfaces and joint. In order to provide an adequate flow property for a fluid and to reduce pressure loss when the fluid is flowing through a conventional reduction, formation of a smooth reducer having no machined surface will reduce the problems and increase the service life of the fitting.

According to a known method a reduction or reducer, is made using a machined piece of a thick walled pipe or by moulding to a required size having a higher angle of inclination, and welded to a main or a branch pipe using a butt fusion or another suitable method. As the reduction pieces are machined the probability of having a notch on the inside and the outside surface of the piece can cause a crack and thereby possible leakage during the application. It is also well known that pipe walls are subject to wear and pressure losses appear at locations where the cross sectional area of a pipe changes, due to the welding and the short length of the reductions particularly if abrasive or similar kind of material is transported in the pipe. Generally the reducers are made in short lengths by way of machining or injection moulding machined pieces, which are welded to, form a reduction in case of small diameter pipes of polymeric material, which becomes more tedious in cases of pipes having a bigger diameter, which is the subject matter of the invention.

Excessive wear occurs generally at a joint. It is also known to reinforce a joint by adding additional material to the pipe near the joint either onto the outside or onto the inside. However when the material is added onto the inside of the pipe (e.g. by a liner) the internal cross section of the pipe is reduced causing an impediment to a flow through the joint. It would not be cost effective to produce pipes for special joints having increased thickness for a small quantity of fittings in discussion. An- ' other method is to reinforce onto the exterior of a pipe near a joint by using either a thermosetting polymer or additional polymer of same type as that in the pipe, which method will need an additional process.

SUMMARY OF THE INVENTION

The object of the present invention is to build up a smooth reduction for any commonly available pipe size, which permits formation of a reduction having a strength equal to or better than that of the machined part, preferably by using standard equipment. Further the object of the invention is to provide an inexpensive method employing the polymeric material of the pipe to form a reduction without affecting the hydraulics of a fluid flowing in the pipe and requiring little preparation to be carried out, by which the method will result in a finished product having a prolonged life even when used under wearing conditions and causing no constriction of flow or increase in the pressure, which would occur by the sudden reduction due to the short length of reductions formed by machining or any other method. This is achieved with a method characterized by the following steps:

- Cutting the pipe to a required length;

- Placing one end of the pipe onto the top of a conical mould member in a bath of a heating medium;

- Heating said end of the pipe by the heating medium in the bath to a softening temperature of the polymeric material;

^' - Applying a pressure to the other end of the pipe in order to push the pipe to a predetermined extent onto the mould member; and - Cooling the heated pipe when pushing is finished.

By this method a smooth reduction for any available pipe size can be built up.

According to a preferred embodiment of the invention heated heating medium is pumped into the bath, which heating medium is arranged to heat the pipe wall both from outside and inside. Preferably the heating medium is continuously circulated between the bath and a heating-equipment. ^; The heating medium is preferably oil, such as ethylene glycol or possibly silicone or any other suitable oil, which will not degrade the pipe surface..

Heating of the heating medium is preferably stopped as soon as a predetermined dimension of the reduction is achieved but the circulation of the heating medium is continued till it is cooled, which will hurry up the cooling process.

The invention also concerns a system for forming a long reducer made of polymeric material comprising:

- An equipment for cutting the pipe to a required length;

- A conical forming member;

- A tank into which said forming member is mounted, said tank having an inlet and an outlet for a heating medium; - An equipment for heating said heating medium; and

- A cylinder piston device mounted on a stationary frame above said tank and arranged to apply a pushing force to a cut pipe placed onto the top of said conical forming member. i The system according to the invention provides a lot of advantages, e.g. the use of a heating medium preferably a liquid for heating only that portion of the exterior and interior surface of a main pipe, where the reduction is to be formed. Such a heating will enable fully controllable heating of the pipe material. The reduction is formed when the heated pipe end is pushed on the conical forming member, the top of which has a smaller diameter than the inner diameter of the pipe to be formed to a reducer. The pipe is pressed towards the conical forming member by means of the cylinder piston equipment pushing the other end of the pipe. Thus the main pipe will be hold in position by the conical forming member and the force of the cylinder piston device requiring no further fixture. The inlet and the outlet of the tank, which advantageously is insulated, are preferably communicating with a heating device, such as a heat exchanger having control means for maintaining a predetermined temperature of the heating medium.

In a preferred embodiment the stationary frame comprises vertical frame posts and a horizontal bar onto which said cylinder piston device is mounted. Said horizontal bar is parallel to the end surface of a pipe, which has been placed onto the top of the conical forming member.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail with reference to the enclosed drawing, wherein

Fig. 1 shows a schematic side view of an example of the system according to the invention;

Fig..2 shows a schematic side view of a pipe placed on the top of a conical forming member according to the invention; i

Fig.3 shows a schematic section of the pipe in Fig. 2 when partially pressed down over the conical forming member;

Fig. 4 shows a schematic section of a reducer in final position of pressing; and

Fig. 5 shows a section of a formed reducer.

DETAILED DESCRIPTION OF THE INVENTION

The system according to the invention for forming a reducer comprises in the disclosed embodiment a cylindrical tank 5 provided with a conical forming member 6 at its bottom, having a dimension and shape corresponding to the inner shape of a re- ' ducer to be formed. The conical forming member 6 has preferably a cone angle in the range of 15 to 20°. The tank 5 is intended to receive a heating medium through an inlet 11 at the upper end of the tank 5 and near the bottom end of the tank 5 is an outlet 12 for said heating medium enabling the heating medium to be circulated be- tween a heat exchanger 2 outside the tank 5 and said tank 5. The heating medium is preferably an oil such as ethylene glycol or silicone. In a preferred embodiment an oil heating system or heat exchanger is used manufactured by Tool temp AG in Switzerland. The heating system, which is connected to an electric source, is controlled by means of a PID temperature controller. The tubes connecting the inlet 11 and outlet 12 to the heat exchanger 2 are preferably heat insulated in order to prevent loss of heat.

The system further comprises a stationary frame with two vertical frame posts 10 connected by a horizontal bar 1, which extends diagonally above the tank 5. A cylin- der piston device 3 is mounted on said horizontal bar 1, concentrically with the central axis of the conical forming member 6. Said cylinder piston device 3 is intended to a apply a pushing force to a previously cut pipe 4, placed concentrically upon the conical forming member 6, as shown in fig. 2. For that reason the end of the piston rod of said cylinder piston device 3 is provided with a horizontal plate 8 acting at the upper end of the pipe 4. The lower end of the pipe 4 is then sunk in a bath formed by the heating medium in the tank 5 and will thus be heated to its softening temperature. When the polymeric material in the pipe wall has reached a sufficient degree of softness the cylinder piston device 3 will be activated to push the pipe downwards over the conical forming member 6 until a predetermined length of the reducer is achieved, i.e. the bottom end of the conically expanded pipe has been pushed to the bottom end of the conical forming member 6 or possibly to a predetermined level above said bottom end. Different stages of the pushing operation is shown in fig. 3 and fig. 4, and in fig. 5 a ready formed reducer 9 is disclosed. EXAMPLE:

When a reducer of 1000x1200 SDR 15 PElOO is to be made a pipe 4 of 1000 . SDRl 5 is used. The lower end of the pipe 4 is heated in the bath to 14O⁰C and by applying a pressure of 100 bar to the cylinder piston device 3. When the pipe 4 has been pushed down to a predetermined level over the conical forming member 6 the entire system is cooled. After cooling the formed reducer is taken out of the bath away from the conical forming device 6, whereby a reducer as that shown in fig. 5 is received. The upper end of the conical forming member 6 has preferably a diameter, which is 25 % smaller than the inner diameter of the pipe 4 and has a cone angle of 20°.

Claims

CLAIMS:

1. Method for forming a reducer from a pipe of polymeric material, characterized by the following steps:

- Cutting the pipe to a required length; - Placing one end of the pipe onto the top of a conical mould member in a bath of a heating medium;

- Applying a pressure to the other end of the pipe in order to push the pipe to a predetermined extent onto the mould member; and

- Cooling the heated pipe when pushing is finished.

2. Method according to claim 1, characterized in that heated heating medium is pumped into the bath, said heating medium being arranged to heat the pipe wall both from outside and inside.

3. Method according to claim 2, characterized in that the heating medium is continuously circulated between the bath and a heating equipment.

4. Method according to claim 1, characterized in that the heating medium is an oil, preferably ethylene glycol or silicone.

5. Method according to any of the preceeding claims, characterized in that heating of the heating medium is stopped as soon as a predetermined dimension of the re- duction is achieved but the circulation of the heating medium is continued till it is cooled.

6. System for forming a reduction from a pipe of polymeric material, characterized in that it comprises: - An equipment for cutting the pipe to a required length;

- A conical forming member; - A tank into which said forming member is mounted, said tank having an inlet and an outlet for a heating medium;

- An equipment for heating said heating medium; and

- A cylinder piston device mounted on a stationary frame above said tank and arranged to apply a pushing force to a cut pipe placed onto the top of said conical forming member.

7. System according to claim 6, characterized in that the inlet and outlet of the tank are communicating with a heating device having control means for maintaining a predetermined temperature of the heating medium.

8. System according to claim 7, characterized in that the tank is insulated.

9. System according to claim 6, characterized in that said frame comprises vertical frame posts and a horizontal bar to which said cylinder piston device is mounted.

10. System according to claim 9, characterized in that the horizontal bar is parallel to the end surface of a pipe placed onto the top of the conical forming member.