Method and device for forming a transverse collar on the end of a metal pipe

A method and device are disclosed for forming the end of a metal pipe into a collar substantially perpendicular to the longitudinal axis of the pipe. The method involves spreading the pipe end into a position perpendicular to the longitudinal direction of the pipe in two or more stages. The device includes an auxiliary head of conic form for spreading the pipe end into a collar substantially perpendicular to the longitudinal axis of the pipe, the auxiliary head being mounted in the device after the pipe end has been spread in a first stage to an angle differing from 0.degree. relative to the longitudinal direction of the pipe. The auxiliary head is so arranged that the working surface of the auxiliary head, when pressed against the pipe end, is substantially perpendicular to the longitudinal direction of the pipe.

FIELD OF THE INVENTION 
The present invention relates to a method and device for forming a collar 
at the end of a metal pipe at an angle substantially perpendicular to the 
longitudinal axis of the pipe. 
DESCRIPTION OF THE PRIOR ART 
Many ways are known of making butted joints between metal pipes. One way is 
that proposed in Finnish Patent No. 70080, in which each pipe end to be 
joined is first formed into a cone-shaped collar disposed at an angle of 
approximately 37.degree. to the longitudinal axis of the pipe. The collar 
can be produced, for example, using a machine provided with a rotating 
cone for expanding the pipe end, the cone being generally movable in a 
lengthwise direction relative to the pipe. The machine includes a frame 
and a chuck attached to the frame by an axle and rotated by an actuator 
incorporated in the device. The chuck is so arranged that it always 
remains aligned with that part of the pipe which is to be collared and 
accommodates an expanding cone for spreading the pipe end from 0.degree. 
to an angle depending on the angle of taper of the cone and the angle 
between the axle of the cone and the longitudinal direction of the pipe. 
The cone is eccentrically and freely rotatably mounted on that end of the 
chuck which points away from the frame, so that the axial direction of the 
cone differs from that of the pipe. Jaws are provided for holding the pipe 
during the collaring operation so that the pipe end to be collared is 
brought close to the expanding cone. The device is also provided with 
means for adjusting the distance between the pipe end and the cone. 
An insert of a corresponding form is placed inside and between the pipe 
ends thus formed and the ends are pressed together by means of flanges 
placed on the pipe ends behind the collars and tightened, e.g. by bolts 
and screws. Such a joint is good in itself and can withstand high 
pressures, such as those commonly used in hydraulic systems, but it is 
also expensive, especially because the insert required must be 
manufactured to great precision. For this reason, this type of joint is 
not favoured in low-pressure systems. 
In another type of flanged joint in common use, the pipe end is provided 
with a collar which is essentially perpendicular to the longitudinal axis 
of the pipe. This can be made in many ways, e.g. by welding a separate 
piece provided with such a collar onto the pipe end. However, this type of 
joint is also expensive and time-consuming to produce. 
Finnish Patent Application No. 791685 proposes a device for collaring a 
pipe end via plastic shaping. The device uses a mandrel which is rolled on 
the inside of the pipe and simultaneously tilted outwardly against the 
pipe wall. The mandrel is controlled by a carriage which is fitted on a 
support provided with arched guide rails in such a manner that, in order 
to tilt the mandrel, the carriage can be moved on the guide rails relative 
to its support by power means connected to the carriage. To produce the 
rolling movement of the mandrel, the carriage support is attached to a 
revolving body. In addition, the mandrel is so attached to the carriage 
that it is radially adjustable. 
With such a device it is naturally possible to shape plastically the pipe 
end, so as to produce a collar at right angles to the longitudinal axis of 
the pipe. However, it has the disadvantages of being complex, heavy and 
expensive. Because of its enormous size and weight, the device cannot be 
taken to the site where the pipes are to be installed. 
BRIEF SUMMARY OF THE INVENTION 
An object of the present invention is to provide a method and device for 
collaring a pipe end for flange jointing in such manner that the collar is 
substantially perpendicular to the longitudinal axis of the pipe and can 
be quickly produced by means of a simple and light device. 
Accordingly, one aspect of the invention provides a method for forming the 
end of a metal pipe into an annular collar substantially perpendicular to 
the longitudinal axis of the pipe, which comprises carrying out the 
operation of expanding the pipe and so as to produce a collar 
perpendicular to the longitudinal axis of the pipe in two or more stages. 
In a preferred embodiment of the method of the invention, the expansion 
operation is carried out in two stages, the first stage consisting in 
expanding the pipe end to an angle of 35-40.degree. using a method known 
per se, while in the second stage the pipe end is expanded further to an 
angle of approximately 90.degree. relative to the longitudinal axis of the 
pipe. 
In another preferred embodiment of the method of the invention, the pipe is 
collared in the first stage with a device known per se using an expanding 
cone, whereupon an auxiliary head is placed on top of the cone or the cone 
is replaced by a different expanding head, so as to carry out the second 
stage of the expansion operation. 
Another aspect of the invention provides a device for forming the end of a 
metal pipe to produce a collar substantially perpendicular to the 
longitudinal direction of the pipe, which device comprises a frame, a 
chuck attached to the frame by an axle and rotated by an actuator 
incorporated in the device, the chuck being so arranged that it always 
remains aligned with that part of the pipe which is to be collared and 
accommodates an expanding cone for spreading the pipe end in a first stage 
from 0.degree. to an angle depending on the angle of taper of the cone and 
the angle between the axle of the cone and the longitudinal direction of 
the pipe, the cone being eccentrically and freely rotatably mounted on 
that end of the chuck which points away from the frame, so that the axial 
direction of the cone differs from that of the pipe, jaws for holding the 
pipe during the collaring operation so that the pipe end to be collared is 
brought close to the expanding cone, the device being provided with means 
for adjusting the distance between the pipe end and the cone, and an 
auxiliary head of conic form for spreading the pipe end in a second stage 
into a collar essentially perpendicular to the longitudinal axis of the 
pipe, said auxiliary head being mounted in the device after the pipe end 
has been spread by said expanding cone in said first stage, the head being 
so arranged that its working surface, when pressed against the pipe end, 
is substantially perpendicular to the longitudinal direction of the pipe. 
A preferred embodiment of the device of the invention includes an auxiliary 
head so designed that it can be mounted on top of the expanding cone, the 
interior surface of the auxiliary head having essentially the same form as 
the outer surface of the expanding cone, so that the auxiliary head can be 
held in place by frictional force. 
In another preferred embodiment of the device of the invention, the 
auxiliary head consists of a different expanding cone, which is mounted in 
place of the first cone after the pipe end has been spread in the first 
stage to an angle differing from 0.degree. relative to the longitudinal 
direction of the pipe. 
The invention offers several advantages over solutions previously known in 
the art. The most important advantages are the small size and portability 
of the device, which makes it easy to transport it to the site of 
installation of the pipes, and the ease and speed of operation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 shows part of a collaring machine known per se which can be used in 
the method of the invention. The machine comprises a frame 1 and a chuck 2 
supported by a shaft attached to the frame, the chuck being rotatable by 
an actuator. In this embodiment, the end of the chuck pointing away from 
the frame is of an oblique form. In existing collaring machines used for 
making collars at an angle of approximately 37.degree. relative to the 
longitudinal direction of the pipe, this oblique end forms an angle of 
approximately 15.degree.-20.degree. to the vertical plane. The oblique end 
is provided with a hole placed eccentrically and accommodating a shaft 5 
of an expanding cone 4, the shaft being so mounted in the hole by means of 
bearings that it is freely rotatable and substantially perpendicular to 
the chuck end surface. The angle of taper of the expanding cone may vary 
depending on the desired angle of the collar and the other angles referred 
to. The angle of the finished collar is determined by the angle between 
the longitudinal axis of pipe 7 and working surface 6 of the expanding 
cone 4. 
The collaring device also comprises holding jaws 8, between which the pipe 
7 is firmly secured during the collaring operation. The length of the 
collar produced depends on how far the end of the pipe 7 protrudes past 
the jaws 8. 
In the first stage, the pipe 7 is secured in place by means of the jaws 8. 
FIG. 2 shows the second stage, in which the rotating chuck 2 moves axially 
towards the pipe 7. The working surface 6 of the expanding cone 4 is now 
pressed against the pipe end, which thus begins to be expanded by virtue 
of the rotation and axial thrust of the chuck, a collar 9 being thus 
formed at the pipe end. During the collaring operation, the expanding cone 
4 rolls freely along the interior surface of the pipe 7, without sliding 
friction. 
When the expanding cone 4, driven by the chuck 2, has advanced far enough 
into the pipe and the desired collar has been produced, the chuck stops 
advancing and begins to withdraw, pulling the expanding cone 4 clear from 
the collar 9. 
The next phase of the operation is illustrated in FIG. 3. As shown, an 
auxiliary head 10 is placed over the expanding cone 4, the angle of taper 
of the auxiliary head being larger than that of the expanding cone 4. That 
part of working surface 11 of the auxiliary head 10 which is pressed 
against the collar 9 is substantially perpendicular to the longitudinal 
direction of the pipe. No other restrictions are imposed on the auxiliary 
head, which means that in other respects it may be designed in almost any 
form. 
FIG. 4 shows a phase of the operation where the chuck 2 has again advanced 
towards the pipe 7. The auxiliary head is pressed against the collar 9, 
expanding it further in the same manner as before. Once the collar has 
been forced into an angle of 90.degree. relative to the longitudinal axis 
of the pipe, the chuck 2 is again withdrawn. 
The above description relates to a device in which the chuck and the 
expanding cone move towards the pipe. However, the device may equally well 
be designed so that the expanding cone is immovable in the axial direction 
of the pipe while the members holding the pipe in place move towards the 
expanding cone. 
FIGS. 5 to 8 show different possible forms of the auxiliary head. In FIGS. 
5 and 6, the auxiliary head 10 consists of an additional member, provided 
with a working surface 11, which is placed over the expanding cone 4. The 
auxiliary head is held in place on the expanding cone by virtue of 
friction, provided that the two pieces are fitted together with sufficient 
precision. It should be noted that the joint between these two pieces is 
not subjected to any axial forces tending to dislodge the auxiliary head 
and only to insignificant tangential dislodging forces, because the cone 
is freely rotatable in the chuck 2. FIG. 5 shows a truncated expanding 
cone 4. This kind of cone is used to make collars in pipes with a large 
diameter. Expanding cones like the one in FIG. 6 are used for collaring 
pipes with a small diameter. 
FIGS. 7 and 8 depict another important embodiment of the invention. The 
auxiliary head need not necessarily be of the kind which is placed on top 
of the expanding cone, but it may instead be a different expanding cone 
12, which is mounted in the chuck after the first stage of the collaring 
operation has been finished. This type of auxiliary head 12 may also be of 
any form, although only two different possibilities are shown in FIGS. 7 
and 8. It should also be noted that it is only for reasons of convenience 
that the cones in FIGS. 5 to 8 are shown in a horizontal position. As 
stated above, in an actual collaring machine the cones are placed in a 
position where the working surface 11 is essentially perpendicular to the 
longitudinal direction of the pipe 7 to be collared. 
The pipes to be collared may be made of various metals. The materials most 
commonly used in hydraulic piping are steel, e.g. St 37, and stainless 
austenitic steel, e.g. AISI 316. The main point is that the material 
should permit cold forming and bending of the pipe. 
It will be obvious to persons skilled in the art that the invention is not 
restricted to the above embodiments, but that it may instead be varied 
within the scope of the following claims. For example, the angle of the 
collar produced in the first stage is not particularly critical. The main 
idea is to produce a collar at an angle differing from 0.degree. to make 
it possible to expand the pipe end further in the second stage to the 
final 90.degree. angle, which can not be done directly on a straight pipe, 
using this type of collaring machine.