Title of Invention	METHOD AND SYSTEM FOR FORMING A BRANCH IN A POLYMERIC PIPE USING HEATED LIQUID IN ORDER TO PLASTICIZE A PIPE WALL SECTION WHICH IS TO BE DISPLACED OUTWARDLY TO FORM SAID BRANCH
Abstract	Method for forming a branch (11) in a pipe (12) of polymeric material characterized by the steps : - making a circular hole (14) in the wall of a main pipe and applying an end of an outer cylindrical mould (9) tightly against outer wall of the main pipe concentrically with said circular hole; - introducing a forming member (6), having a conical nose, into the main pipe through one end, and fixing it to an end of a puller device (5) brought into the main pipe through said circular hole ; - applying heat to a portion of the exterior surface of the pipe wall defined by the mould (9), using a liquid heated to a temperature less than the melting temperature of the polymeric material ; - pulling the forming member gradually toward the exterior of the pipe through the plasticized wall portion coaxially with the mould (9) whereby the plasticized polymeric material is displaced outwardly to form said branch extending outwardly from the main pipe wall.

Title of Invention

METHOD AND SYSTEM FOR FORMING A BRANCH IN A POLYMERIC PIPE USING HEATED LIQUID IN ORDER TO PLASTICIZE A PIPE WALL SECTION WHICH IS TO BE DISPLACED OUTWARDLY TO FORM SAID BRANCH

Abstract

Method for forming a branch (11) in a pipe (12) of polymeric material characterized by the steps : - making a circular hole (14) in the wall of a main pipe and applying an end of an outer cylindrical mould (9) tightly against outer wall of the main pipe concentrically with said circular hole; - introducing a forming member (6), having a conical nose, into the main pipe through one end, and fixing it to an end of a puller device (5) brought into the main pipe through said circular hole ; - applying heat to a portion of the exterior surface of the pipe wall defined by the mould (9), using a liquid heated to a temperature less than the melting temperature of the polymeric material ; - pulling the forming member gradually toward the exterior of the pipe through the plasticized wall portion coaxially with the mould (9) whereby the plasticized polymeric material is displaced outwardly to form said branch extending outwardly from the main pipe wall.

Full Text	Method and system for forming a branch in a polymeric pipe, using heated liquid in order to plasticize a pipe wall section which is to be displaced outwardly to form said branch. BACKGROUND OF THE INVENTION This invention relates to a method for forming a branch in a pipe of polymeric ma- terial. Formation of a branch in pipe causes several known problems, for instance weakness at the joint. Lack of strength may arise among other reasons due to lack of an adequate surface for providing a connection between the pipes to be joined. In order to provide an adequate joint between a branch pipe of a smaller diameter ex- tending perpendicularly to a straight section of a main pipe having a larger diame- ter, particular problems will arise. According to a known method a joint between a branch pipe and a main pipe hav- ing a larger diameter is formed by making a circular hole corresponding to the size of said branch pipe into the wall of the main pipe e.g. by using a hole saw or an- other suitable equipment. The pipes are then connected by welding the outer side- wall of the branch pipe to the inner sidewall of the main pipe. Another method of forming a branch in pipe is to cut out a V-shaped section from a main pipe and cut- ting one end of a branch pipe mating V-shape and sized to be received in the V- shaped opening in the main pipe. Connection of the branch pipe to the main pipe is achieved by welding the outer sidewall of the branch pipe to the sidewall of the main pipe. A sidewall weld connection is much more inferior than a joint connec- tion between adjacent coaxial pipes. It is also well known that pipes are subject to wear at locations where a pipe changes direction particularly if abrasive material is transported in the pipe. Exces- sive wear occurs generally at the joint. It is known to reinforce a joint by adding additional material to the pipe near the joint either onto the outside or onto the in- side. 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. Another method to reinforce onto the exterior of a pipe near a joint is to use either a thermosetting polymer or additional polymer of same type as that in the pipe, which method will need an additional mould process. US patent No. 5 958 172 discloses a method of forming a reinforced joint of polymeric material, comprising the steps of : forcing a first pipe section of polymeric material into a second pipe section of polymeric material to expand the second pipe section for securing the first pipe section in the second pipe section, thereby forming a first reinforced joint element ; forcing a third pipe section of polymeric material into a fourth pipe section of polymeric material to thereby securely fix the third pipe section in the fourth pipe section and form a second reinforced joint element ; cutting the first reinforced joint element transversely in a plane skewed relative to the longitudinal axis of the first reinforced joint element; and connecting the first reinforced joint element to the second reinforced joint element to form the reinforced joint which is angled. The present invention has been devised to form such a joint in a pipe to overcome the disadvantages of prior art. The distinguishing features of the present invention over prior art would be evident from the description given hereinafter. SUMMARY OF THE INVENTION The object of the present invention is to build up a branch in pipe of any commonly available pipe size, which permits formation of a joint on the branch, which is as strong as a joint between coaxial pipes, 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 branch without damaging the pipe and requiring little preparation to be carried out, which method will result in a finished branch having a prolonged life even when used under wearing conditions and causing no constriction of flow through the branch. This is achieved with a method comprising the steps of: - making a circular hole in the wall of a main pipe, said hole being considerably smaller than the size of a branch to be formed ; - applying an end of an outer cylindrical mould tightly against the outer wall of the main pipe concentrically with said circular hole ; - introducing a forming member, having a conical nose, into the main pipe through one end ; - fixing the forming member to an end of a puller device brought into the main pipe through said circular hole ; - applying heat to a portion of the exterior surface of the pipe wall defined by said outer mould, using a suitable liquid heated to a temperature less than the melting temperature of the polymeric material in order to plasticize but to prevent degradation of the polymeric material in the pipe wall, which plasticized material is intended to form the branch ; - pulling the forming member gradually toward the exterior of the pipe through the plasticized wall portion coaxially with the cylindrical outer mould whereby the plasticized polymeric material of the pipe wall is displaced outwardly forming said branch, generally in the shape of a pipe section extending outwardly from the main pipe wall. The liquid used for heating the polymeric material of the pipe is preferably oil, such as ethylene glycol or possibly silicone. Further features of the method according to the invention will appear from the attached dependent method claims. The invention also concerns a system for forming a branch in a pipe made of poly- meric material comprising: - an equipment for making a circular hole in the wall of the pipe, said hole being considerably smaller than the size of a branch to be formed; - a forming member with a conical nose to be introduced into the pipe, - a pulling device to be connected to the conical forming member for pulling it through the hole in the pipe wall, - a cylindrical mould having a free end toward which outer surface of said pipe is to be tightly pressed by means of the forming member connected to the pulling de- vice, to define a circular portion of the pipe wall extending concentrically around said hole, - a heating liquid supply and a heating liquid outflow from said mould for heating said portion of the exterior surface of the pipe. The system according to the invention provides a lot of advantages, e.g. the use of a liquid medium for heating only that portion of the exterior surface of a main pipe, where a branch pipe is to be formed. Such a heating will enable fully controllable heating of the pipe material. The branch is formed when the forming member is pulled through the hole in the pipe wall. The cylindrical mould of the system forms a chamber for the heating liquid, when the pipe wall is pressed towards the lower end of said cylindrical mould by means of the forming member pulled by the pull- ing device of the system. Thus the main pipe will also be held in position by the cooperating mould and the forming member, so no further fixture is needed. Further features of the system according to the invention will appear from the embodiments described hereinafter. The mould of the required diameter has a liquid inlet which allows liquid to flow while the pipe is pulled by the forming member under a low pressure such that no damage to the pipe surface occurs. When the polymeric material in the heated portion of the pipe wall becomes plastic the forming member will gradually pass through the hole made in the pipe wall, said hole having a diameter considerably smaller than the inner diameter of the branch to be formed. The liquid is heated under controlled conditions in a heating device provided with suitable control means. The forming member is provided with a conical nose and sized to define an inside diameter of the branch to be formed. The nose of the forming member is connectable to a puller device outside the pipe for pulling the forming member through the hole in the pipe wall generally from the interior of the pipe to the exterior of the pipe. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS The present invention will now be described in more detail with reference to the accompanying drawings, wherein : Fig: 1 is a schematic plan view of a system according to the invention for forming a branch in a pipe made of polymeric material with parts of pipe broken away. Fig: 2 is a partial enlargement of the system shown in fig. 1 with a pipe in contact with the outer cylindrical mould of the system. Fig: 3 is a schematic cross section of the pipe in fig 2 showing the forming mem- ber just prior to being pulled through the pipe. Fig: 4 is a schematic cross section of the pipe showing the forming member in a stage with its nose partly pulled through the pipe. Fig: 5 is a schematic section of the pipe and the mould showing the forming member in its final position. Fig: 6 is a longitudinal section through a pipe having a branch. DETAIL DESCRIPTION OF A PREFERED EMBODIMENT In the drawings a system for forming a branch 11 (Fig 6) in a pipe 12 is discloseu, which pipe is made from a polymeric material of polyolefines such as HDPE. The system comprises a stationary frame 1 provided with vertical frame posts and a horizontal bar to which a mould 9 for a required pipe diameter is connectable. A pair of cylinder piston devices 3 is mounted to said frame posts and connected with their shafts 10 to a horizontal, vertically movable frame 2, positioned above the horizontal bar of the stationary frame 1. The system further includes a cylindrical forming member 6 having a conical nose. The cylindrical body of said forming member 6 is sized to form an inner diameter of a branch 11 to be formed in a pipe 12. The end of the conical nose is connectable to an end of a puller rod 5 having its opposite end connected to the vertically mov- able bar 2. The connection between the forming member 6 and the puller rod 5 can be a thread connection using a connecting sleeve 16 at one end of the puller rod 5. The mould 9 connected to the horizontal bar of the stationary frame 1 is intended to form a chamber 13 to receive a heating liquid when a mantle of a pipe 12 is pulled or pushed towards the bottom end of said mould 9. The heating liquid is preferably an oil such as ethylene glycol or silicone, which is pumped into the chamber 13 through a tube 7 capable of withstanding 150°C. The mould 9 is also provided with an outlet tube 8, through which the oil will flow back to an oil tank 4. The oil is preferably heated in said tank 4 by a heat exchanger. In a preferred embodiment an oil-heating system manufactured by Tool Temp AG of Switzerland is used. The system, which is connected to an electric source, is con- trolled by means of a PID temperature controller. The tubes 7 and 8 and the mould are preferably heat insulated, in order to prevent loss of heat. As shown in fig 3, the mould 9 is mounted on the frame 1 by means of bolts 18. "When a branch 11 is to be formed in a pipe 12, a small hole 14 (Tig. 3), somewhat larger than the puller rod 5 is made in the pipe wall, at a position where the branch 11 is to be formed. The forming member 6 is inserted into the pipe 12 through one end on said pipe and the end of the puller rod 5 is brought into said pipe 12 through the hole 14, whereupon the puller rod 5 is connected to the conical nose of the forming member 6. When the forming member 6 has been secured to the puller rod 5 the cylinder piston devices 3 are activated to slightly push the frame 2 and thus the forming member 6 upwards pressing the outer mantle of the pipe 12 against the bottom end of the mould 9 and simultaneously closing the hole 14 in the pipe wall, resulting in a tight contact between the pipe mantle and the bottom end of the mould 9. Heating liquid, e.g. ethylene glycol having a preset temperature is fed to the chamber 13 formed by the mould and the mantle of the pipe 12, heating a por- tion of the outer surface of the pipe wall defined by the bottom end of the mould 9. As the temperature reaches a level where the polymeric material in the pipe wall just changes from a solid state to a plastic state, the forming medium 6 is pulled outwards through the hole 14 by further activating the pair of cylinder piston de- vices 3, whereby the bar 2 and thus the forming member 6 will be pulled upwards The cylinder piston devices 3 are activated to pull the forming member 6 from the interior of the pipe 12 through the pipe wall to the exterior of the pipe to form the branch 11 by deforming the heated portion of the pipe wall, as schematically shown in Fig. 5. The supply of heating oil to the chamber 13 is stopped, all oil is returned to the oil tank 4 through tube 8, and the plastic material in the formed branch is allowed to cool, whereupon the pipe 12 with the formed branch is removed from the mould 9. It is understood that depending on the diameter of the pipe and the size of the branch 11 to be formed, moulds 9 and forming members 6 of different sizes are to be used, because the mould is intended to define the outer diameter of the branch 11 and the forming member 6 is intended to define the inner diameter of the branch 11 .The bottom end of the mould 9 is concavely shaped to match with the shape of the mantle of the main pipe 12. The heating of the pipe wall is thus largely confined to the area through which die forming member 6 will be pulled. The heating by oil is carried out at an oil tem perature adjusted to a level required by the plastic material in the pipe wall. During the heating stage the heating oil is circulated through tube 7 from the oil tank 4 to the mould 9 and through tube 8 back to the oil tank. When for instance a branch having a diameter of 450 mm is to be formed in a pipe 900 SDR 17 PE 100, the forming member 6 will be pulled to deform the plastic material in the pipe wall when the temperature of the plastic material reaches 130°C by applying a pressure of 50 bar for pulling the forming member 6, whereby a branch of 450 SDR 17 is received. Due to the heating with oil the surface of the heated plastic material is prevented for being oxidized, because the surface of the pipe wall will be covered by oil, all the time the plastic material is at an elevated temperature. Consequently the surface will not be in contact with the outer air before the plastic material is cooled. Preferably the diameter of the forming member 6 is somewhat larger than the inner diameter of a branch 11 to be formed, in order to allow a slight contraction of said inner diameter during cooling. When the forming member 6 is removed after suffi- cient cooling of the exterior surface of the pipe 12, the branch 11 thus formed will be suitable for application. WE CLAIM : 1. Method for forming a branch in a pipe of polymeric material, comprising the following steps : - making a circular hole in the wall of a main pipe, said hole being considerably smaller than the size of a branch to be formed ; - applying an end of an outer cylindrical mould tightly against the outer wall of the main pipe concentrically with said circular hole ; - introducing a forming member, having a conical nose, into the main pipe through one end ; - fixing the forming member to an end of a puller device brought into the main pipe through said circular hole ; - applying heat to a portion of the exterior surface of the pipe wall defined by said outer mould, using a liquid heated to a temperature less than the melting temperature of the polymeric material in order to plasticize but to prevent degradation of the polymeric material in the pipe wall which plasticized material is intended to form the branch ; - pulling the forming member gradually toward the exterior of the pipe through the plasticized wall portion coaxially with the cylindrical outer mould whereby the plasticized polymeric material of the pipe wall is displaced outwardly forming said branch, generally in the shape of a pipe section extending outwardly from the main pipe wall. 2. Method as claimed in claim 1, wherein the heated liquid is pumped into the outer mould as soon as the forming member has been pulled by means of the puller device against the pipe wall and simultaneously pressed the outer surface of the pipe wall into tight contact against the end of the outer mould, which liquid covers a portion of the outer pipe wall defined by said outer mould. 3. Method as claimed in claim 2, wherein the heated liquid is continuously circulated between the interior of the outer mould and a tank provided with heating and control means. 4. Method as claimed in claim 1, wherein the liquid is an oil, e.g. ethylene glycol or silicone. 5. Method as claimed in any of the preceding claims, wherein circulation of heated liquid is stopped and all liquid is removed from the outer mould when forming member has been pulled through the pipe wall. 6. System for forming a brancn in a pipe made of polymeric material, said system comprising : - an equipment for making a circular hole in the wall of the pipe, said hole being considerably smaller than the size of a branch to be formed ; - a forming member with a conical nose to be introduced into the pipe, - a pulling device to be connected to the conical forming member for pulling it through the hole in the pipe wall, - a cylindrical mould having a free end toward which outer surface of said pipe is to be tightly pressed by means of the forming member connected to the pulling device, to define a circular portion of the pipe wall extending concentrically around said hole, and - a heating liquid supply and a heating liquid outflow from said mould for heating said portion of the exterior surface of the pipe. 7. System as claimed in claim 6, wherein said cylindrical mould is provided with a liquid supply and a liquid outlet communicating with a liquid tank provided with a heating device having suitable control means for maintaining a predefined liquid temperature. 8. System as claimed in claim 7, comprising a stationary frame provided with vertical frame posts and a horizontal bar to which the mould for a predetermined pipe dimension is connectable, a pair of cylinder piston devices mounted to said frame posts and connected with their shafts to a horizontal, vertically movable frame, positioned above the horizontal bar of the stationary frame, one end of a puller rod being connected to said movable frame, the opposite end of said puller rod being connectable to the conical nose of a forming member inserted through one end into a pipe to be provided with a branch. 9. System as claimed in claim 8, wherein the free end of the cylindrical mould is concavely shaped to match with the outer surface of the pipe to be provided with a branch. Method for forming a branch (11) in a pipe (12) of polymeric material characterized by the steps : - making a circular hole (14) in the wall of a main pipe and applying an end of an outer cylindrical mould (9) tightly against outer wall of the main pipe concentrically with said circular hole; - introducing a forming member (6), having a conical nose, into the main pipe through one end, and fixing it to an end of a puller device (5) brought into the main pipe through said circular hole ; - applying heat to a portion of the exterior surface of the pipe wall defined by the mould (9), using a liquid heated to a temperature less than the melting temperature of the polymeric material ; - pulling the forming member gradually toward the exterior of the pipe through the plasticized wall portion coaxially with the mould (9) whereby the plasticized polymeric material is displaced outwardly to form said branch extending outwardly from the main pipe wall.

Full Text

Method and system for forming a branch in a polymeric pipe, using heated
liquid in order to plasticize a pipe wall section which is to be displaced
outwardly to form said branch.
BACKGROUND OF THE INVENTION
This invention relates to a method for forming a branch in a pipe of polymeric ma-
terial. Formation of a branch in pipe causes several known problems, for instance
weakness at the joint. Lack of strength may arise among other reasons due to lack
of an adequate surface for providing a connection between the pipes to be joined. In
order to provide an adequate joint between a branch pipe of a smaller diameter ex-
tending perpendicularly to a straight section of a main pipe having a larger diame-
ter, particular problems will arise.
According to a known method a joint between a branch pipe and a main pipe hav-
ing a larger diameter is formed by making a circular hole corresponding to the size
of said branch pipe into the wall of the main pipe e.g. by using a hole saw or an-
other suitable equipment. The pipes are then connected by welding the outer side-
wall of the branch pipe to the inner sidewall of the main pipe. Another method of
forming a branch in pipe is to cut out a V-shaped section from a main pipe and cut-
ting one end of a branch pipe mating V-shape and sized to be received in the V-
shaped opening in the main pipe. Connection of the branch pipe to the main pipe is
achieved by welding the outer sidewall of the branch pipe to the sidewall of the
main pipe. A sidewall weld connection is much more inferior than a joint connec-
tion between adjacent coaxial pipes.
It is also well known that pipes are subject to wear at locations where a pipe
changes direction particularly if abrasive material is transported in the pipe. Exces-
sive wear occurs generally at the joint. It is known to reinforce a joint by adding
additional material to the pipe near the joint either onto the outside or onto the in-
side. 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. Another method
to reinforce onto the exterior of a pipe near a joint is to use either a thermosetting polymer
or additional polymer of same type as that in the pipe, which method will need an
additional mould process.
US patent No. 5 958 172 discloses a method of forming a reinforced joint of
polymeric material, comprising the steps of : forcing a first pipe section of polymeric
material into a second pipe section of polymeric material to expand the second pipe
section for securing the first pipe section in the second pipe section, thereby forming a
first reinforced joint element ; forcing a third pipe section of polymeric material into a
fourth pipe section of polymeric material to thereby securely fix the third pipe section in
the fourth pipe section and form a second reinforced joint element ; cutting the first
reinforced joint element transversely in a plane skewed relative to the longitudinal axis of
the first reinforced joint element; and connecting the first reinforced joint element to the
second reinforced joint element to form the reinforced joint which is angled.
The present invention has been devised to form such a joint in a pipe to overcome
the disadvantages of prior art. The distinguishing features of the present invention over
prior art would be evident from the description given hereinafter.
SUMMARY OF THE INVENTION
The object of the present invention is to build up a branch in pipe of any commonly
available pipe size, which permits formation of a joint on the branch, which is as strong
as a joint between coaxial pipes, 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 branch without damaging the pipe and requiring little
preparation to be carried out, which method will result in a finished branch having a
prolonged life even when used under wearing conditions and causing no constriction of
flow through the branch.

This is achieved with a method comprising the steps of:
- making a circular hole in the wall of a main pipe, said hole being considerably smaller
than the size of a branch to be formed ;
- applying an end of an outer cylindrical mould tightly against the outer wall of the main
pipe concentrically with said circular hole ;
- introducing a forming member, having a conical nose, into the main pipe through one
end ;
- fixing the forming member to an end of a puller device brought into the main pipe
through said circular hole ;
- applying heat to a portion of the exterior surface of the pipe wall defined by said outer
mould, using a suitable liquid heated to a temperature less than the melting temperature
of the polymeric material in order to plasticize but to prevent degradation of the
polymeric material in the pipe wall, which plasticized material is intended to form the
branch ;

- pulling the forming member gradually toward the exterior of the pipe through the
plasticized wall portion coaxially with the cylindrical outer mould whereby the
plasticized polymeric material of the pipe wall is displaced outwardly forming said
branch, generally in the shape of a pipe section extending outwardly from the main
pipe wall.
The liquid used for heating the polymeric material of the pipe is preferably oil, such
as ethylene glycol or possibly silicone. Further features of the method according to
the invention will appear from the attached dependent method claims.
The invention also concerns a system for forming a branch in a pipe made of poly-
meric material comprising:
- an equipment for making a circular hole in the wall of the pipe, said hole being
considerably smaller than the size of a branch to be formed;
- a forming member with a conical nose to be introduced into the pipe,
- a pulling device to be connected to the conical forming member for pulling it
through the hole in the pipe wall,
- a cylindrical mould having a free end toward which outer surface of said pipe is to
be tightly pressed by means of the forming member connected to the pulling de-
vice, to define a circular portion of the pipe wall extending concentrically around
said hole,
- a heating liquid supply and a heating liquid outflow from said mould for heating
said portion of the exterior surface of the pipe.
The system according to the invention provides a lot of advantages, e.g. the use of a
liquid medium for heating only that portion of the exterior surface of a main pipe,
where a branch pipe is to be formed. Such a heating will enable fully controllable
heating of the pipe material. The branch is formed when the forming member is
pulled through the hole in the pipe wall. The cylindrical mould of the system forms
a chamber for the heating liquid, when the pipe wall is pressed towards the lower
end of said cylindrical mould by means of the forming member pulled by the pull-

ing device of the system. Thus the main pipe will also be held in position by the
cooperating mould and the forming member, so no further fixture is needed.
Further features of the system according to the invention will appear from the
embodiments described hereinafter.
The mould of the required diameter has a liquid inlet which allows liquid to flow while
the pipe is pulled by the forming member under a low pressure such that no damage to the
pipe surface occurs. When the polymeric material in the heated portion of the pipe wall
becomes plastic the forming member will gradually pass through the hole made in the
pipe wall, said hole having a diameter considerably smaller than the inner diameter of the
branch to be formed. The liquid is heated under controlled conditions in a heating device
provided with suitable control means. The forming member is provided with a conical
nose and sized to define an inside diameter of the branch to be formed. The nose of the
forming member is connectable to a puller device outside the pipe for pulling the forming
member through the hole in the pipe wall generally from the interior of the pipe to the
exterior of the pipe.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The present invention will now be described in more detail with reference to the
accompanying drawings, wherein :
Fig: 1 is a schematic plan view of a system according to the invention for forming a
branch in a pipe made of polymeric material with parts of pipe broken away.
Fig: 2 is a partial enlargement of the system shown in fig. 1 with a pipe in contact with
the outer cylindrical mould of the system.

Fig: 3 is a schematic cross section of the pipe in fig 2 showing the forming mem-
ber just prior to being pulled through the pipe.
Fig: 4 is a schematic cross section of the pipe showing the forming member in a
stage with its nose partly pulled through the pipe.
Fig: 5 is a schematic section of the pipe and the mould showing the forming
member in its final position.
Fig: 6 is a longitudinal section through a pipe having a branch.
DETAIL DESCRIPTION OF A PREFERED EMBODIMENT
In the drawings a system for forming a branch 11 (Fig 6) in a pipe 12 is discloseu,
which pipe is made from a polymeric material of polyolefines such as HDPE.
The system comprises a stationary frame 1 provided with vertical frame posts and a
horizontal bar to which a mould 9 for a required pipe diameter is connectable. A
pair of cylinder piston devices 3 is mounted to said frame posts and connected with
their shafts 10 to a horizontal, vertically movable frame 2, positioned above the
horizontal bar of the stationary frame 1.
The system further includes a cylindrical forming member 6 having a conical nose.
The cylindrical body of said forming member 6 is sized to form an inner diameter
of a branch 11 to be formed in a pipe 12. The end of the conical nose is connectable
to an end of a puller rod 5 having its opposite end connected to the vertically mov-
able bar 2. The connection between the forming member 6 and the puller rod 5 can
be a thread connection using a connecting sleeve 16 at one end of the puller rod 5.
The mould 9 connected to the horizontal bar of the stationary frame 1 is intended to
form a chamber 13 to receive a heating liquid when a mantle of a pipe 12 is pulled
or pushed towards the bottom end of said mould 9. The heating liquid is preferably

an oil such as ethylene glycol or silicone, which is pumped into the chamber 13
through a tube 7 capable of withstanding 150°C. The mould 9 is also provided with
an outlet tube 8, through which the oil will flow back to an oil tank 4. The oil is
preferably heated in said tank 4 by a heat exchanger.
In a preferred embodiment an oil-heating system manufactured by Tool Temp AG
of Switzerland is used. The system, which is connected to an electric source, is con-
trolled by means of a PID temperature controller. The tubes 7 and 8 and the mould
are preferably heat insulated, in order to prevent loss of heat.
As shown in fig 3, the mould 9 is mounted on the frame 1 by means of bolts 18.
"When a branch 11 is to be formed in a pipe 12, a small hole 14 (Tig. 3), somewhat
larger than the puller rod 5 is made in the pipe wall, at a position where the branch
11 is to be formed. The forming member 6 is inserted into the pipe 12 through one
end on said pipe and the end of the puller rod 5 is brought into said pipe 12 through
the hole 14, whereupon the puller rod 5 is connected to the conical nose of the
forming member 6. When the forming member 6 has been secured to the puller rod
5 the cylinder piston devices 3 are activated to slightly push the frame 2 and thus
the forming member 6 upwards pressing the outer mantle of the pipe 12 against the
bottom end of the mould 9 and simultaneously closing the hole 14 in the pipe wall,
resulting in a tight contact between the pipe mantle and the bottom end of the
mould 9. Heating liquid, e.g. ethylene glycol having a preset temperature is fed to
the chamber 13 formed by the mould and the mantle of the pipe 12, heating a por-
tion of the outer surface of the pipe wall defined by the bottom end of the mould 9.
As the temperature reaches a level where the polymeric material in the pipe wall
just changes from a solid state to a plastic state, the forming medium 6 is pulled
outwards through the hole 14 by further activating the pair of cylinder piston de-
vices 3, whereby the bar 2 and thus the forming member 6 will be pulled upwards
The cylinder piston devices 3 are activated to pull the forming member 6 from the
interior of the pipe 12 through the pipe wall to the exterior of the pipe to form the

branch 11 by deforming the heated portion of the pipe wall, as schematically shown
in Fig. 5. The supply of heating oil to the chamber 13 is stopped, all oil is returned
to the oil tank 4 through tube 8, and the plastic material in the formed branch is
allowed to cool, whereupon the pipe 12 with the formed branch is removed from
the mould 9.
It is understood that depending on the diameter of the pipe and the size of the
branch 11 to be formed, moulds 9 and forming members 6 of different sizes are to
be used, because the mould is intended to define the outer diameter of the branch 11
and the forming member 6 is intended to define the inner diameter of the branch
11 .The bottom end of the mould 9 is concavely shaped to match with the shape of
the mantle of the main pipe 12.
The heating of the pipe wall is thus largely confined to the area through which die
forming member 6 will be pulled. The heating by oil is carried out at an oil tem
perature adjusted to a level required by the plastic material in the pipe wall. During
the heating stage the heating oil is circulated through tube 7 from the oil tank 4 to
the mould 9 and through tube 8 back to the oil tank. When for instance a branch
having a diameter of 450 mm is to be formed in a pipe 900 SDR 17 PE 100, the
forming member 6 will be pulled to deform the plastic material in the pipe wall
when the temperature of the plastic material reaches 130°C by applying a pressure
of 50 bar for pulling the forming member 6, whereby a branch of 450 SDR 17 is
received.
Due to the heating with oil the surface of the heated plastic material is prevented for
being oxidized, because the surface of the pipe wall will be covered by oil, all the
time the plastic material is at an elevated temperature. Consequently the surface
will not be in contact with the outer air before the plastic material is cooled.
Preferably the diameter of the forming member 6 is somewhat larger than the inner
diameter of a branch 11 to be formed, in order to allow a slight contraction of said

inner diameter during cooling. When the forming member 6 is removed after suffi-
cient cooling of the exterior surface of the pipe 12, the branch 11 thus formed will
be suitable for application.

WE CLAIM :
1. Method for forming a branch in a pipe of polymeric material, comprising the
following steps :
- making a circular hole in the wall of a main pipe, said hole being considerably smaller
than the size of a branch to be formed ;
- applying an end of an outer cylindrical mould tightly against the outer wall of the main
pipe concentrically with said circular hole ;
- introducing a forming member, having a conical nose, into the main pipe through one
end ;
- fixing the forming member to an end of a puller device brought into the main pipe
through said circular hole ;
- applying heat to a portion of the exterior surface of the pipe wall defined by said outer
mould, using a liquid heated to a temperature less than the melting temperature of the
polymeric material in order to plasticize but to prevent degradation of the polymeric
material in the pipe wall which plasticized material is intended to form the branch ;
- pulling the forming member gradually toward the exterior of the pipe through the
plasticized wall portion coaxially with the cylindrical outer mould whereby the
plasticized polymeric material of the pipe wall is displaced outwardly forming said
branch, generally in the shape of a pipe section extending outwardly from the main pipe
wall.
2. Method as claimed in claim 1, wherein the heated liquid is pumped into the outer
mould as soon as the forming member has been pulled by means of the puller device
against the pipe wall and simultaneously pressed the outer surface of the pipe wall into
tight contact against the end of the outer mould, which liquid covers a portion of the outer
pipe wall defined by said outer mould.

3. Method as claimed in claim 2, wherein the heated liquid is continuously circulated
between the interior of the outer mould and a tank provided with heating and control
means.
4. Method as claimed in claim 1, wherein the liquid is an oil, e.g. ethylene glycol or
silicone.
5. Method as claimed in any of the preceding claims, wherein circulation of heated
liquid is stopped and all liquid is removed from the outer mould when forming member
has been pulled through the pipe wall.
6. System for forming a brancn in a pipe made of polymeric material, said system
comprising :
- an equipment for making a circular hole in the wall of the pipe, said hole being
considerably smaller than the size of a branch to be formed ;
- a forming member with a conical nose to be introduced into the pipe,
- a pulling device to be connected to the conical forming member for pulling it through
the hole in the pipe wall,
- a cylindrical mould having a free end toward which outer surface of said pipe is to be
tightly pressed by means of the forming member connected to the pulling device, to
define a circular portion of the pipe wall extending concentrically around said hole, and
- a heating liquid supply and a heating liquid outflow from said mould for heating said
portion of the exterior surface of the pipe.
7. System as claimed in claim 6, wherein said cylindrical mould is provided with a
liquid supply and a liquid outlet communicating with a liquid tank provided with a
heating device having suitable control means for maintaining a predefined liquid
temperature.

8. System as claimed in claim 7, comprising a stationary frame provided with
vertical frame posts and a horizontal bar to which the mould for a predetermined pipe
dimension is connectable, a pair of cylinder piston devices mounted to said frame posts
and connected with their shafts to a horizontal, vertically movable frame, positioned
above the horizontal bar of the stationary frame, one end of a puller rod being connected
to said movable frame, the opposite end of said puller rod being connectable to the
conical nose of a forming member inserted through one end into a pipe to be provided
with a branch.
9. System as claimed in claim 8, wherein the free end of the cylindrical mould is
concavely shaped to match with the outer surface of the pipe to be provided with a
branch.

Method for forming a branch (11) in a pipe (12) of polymeric material
characterized by the steps :
- making a circular hole (14) in the wall of a main pipe and applying an end of an outer
cylindrical mould (9) tightly against outer wall of the main pipe concentrically with said
circular hole;
- introducing a forming member (6), having a conical nose, into the main pipe through
one end, and fixing it to an end of a puller device (5) brought into the main pipe through
said circular hole ;
- applying heat to a portion of the exterior surface of the pipe wall defined by the mould
(9), using a liquid heated to a temperature less than the melting temperature of the
polymeric material ;
- pulling the forming member gradually toward the exterior of the pipe through the
plasticized wall portion coaxially with the mould (9) whereby the plasticized polymeric
material is displaced outwardly to form said branch extending outwardly from the main
pipe wall.

Documents:

1613-KOLNP-2004-CORRESPONDENCE.pdf

1613-KOLNP-2004-FORM 27.pdf

1613-kolnp-2004-granted-abstract.pdf

1613-kolnp-2004-granted-assignment.pdf

1613-kolnp-2004-granted-claims.pdf

1613-kolnp-2004-granted-correspondence.pdf

1613-kolnp-2004-granted-description (complete).pdf

1613-kolnp-2004-granted-drawings.pdf

1613-kolnp-2004-granted-examination report.pdf

1613-kolnp-2004-granted-form 1.pdf

1613-kolnp-2004-granted-form 3.pdf

1613-kolnp-2004-granted-form 5.pdf

1613-kolnp-2004-granted-gpa.pdf

1613-kolnp-2004-granted-reply to examination report.pdf

1613-kolnp-2004-granted-specification.pdf

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Patent Number

231402

Indian Patent Application Number

1613/KOLNP/2004

PG Journal Number

10/2009

Publication Date

06-Mar-2009

Grant Date

04-Mar-2009

Date of Filing

29-Oct-2004

Name of Patentee

OY KWH PIPE AB

Applicant Address

KAPELLBACKSVAGEN 240, FIN-65370 VASA

Inventors:

#	Inventor's Name	Inventor's Address
1	OOMMEN AJAY	700/318 MOO 6 SOI 14 AMATANAKORN INDUSTRIAL ESTATE, T.DON HUA RO 20000 A. MUANG CHONBURI

PCT International Classification Number

F16L 47/26

PCT International Application Number

PCT/FI03/00362

PCT International Filing date

2003-05-09

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	20020934	2002-05-17	Finland