FIELD OF THE INVENTION
The present invention relates to a device in an welding machine for welding of
bifurcate objects installed on power boilers.
BACKGROUND OF THE INVENTION
Bifurcate consists of an U tube and a branch. The branch tube is welded at the
bend centre of the U tube. In super critical power boilers with vertical wall tube,
the number of bifurcate required are in thousands. Before welding the U tube
and the branch tube, a hole at the centre of bend in the U tube is machined and
edge prepared. While welding the U tube and the branch tube, the axis
alignment to be ensued. For this welding, welding device is releasably attached
to the welding machine. The device comprises at least one each support
member for holding the U tube (Figure 1) and the branch tube (Figure 2). Both
are mounted on the machine bed.
The U tube holding means (Figure 1) consists of a plurality of adjustments
features, and a clamp to align the U tube along the axis of machine. This sub
assembly is mounted on a rotating face plate, which warrants a longer setting
time for alignment of the U tube along the axis of the machine. Further, a
perfect axis alignment is not always achieved even after many adjustments and
clamping, which leads to rejections of the final component.
The Branch tube holding means (Figure 2) acts as a steady rest and is directly
mounted on the machine bed. The branch tube is clamped in between two
bearings mounted on the steady rest. Alignment of the height of centre and axis
is automatically attained with this.
OBJECT OF THE INVENTION
It is therefore an object of the invention to propose a device in an welding machine
for welding of bifurcate objects installed on power boilers which enables a
perfect self alignment of the device without repeated adjustments.
SUMMARY OF THE INVENTION
According to the invention, the device comprises a holding means and a steady-
rest means, and allows an automatic axis alignment of the holding means in
respect of the machine spindle.
The holding means in configured into at least two segments, the first segment
constitutes a movable v-block assembly, and the second segment constitutes a
steady rest means. The device further comprising a branch tube holder.
The V-block assembly comprises a base plate mountable on the face plate of
the machine. A guide plate which holds one each right hand and left hand (LH)
threaded blocks is screwably attached to the base plate. A screw rod with RH &
LH threads cause the threaded blocks to move inward or outward equally with
respect to the machine centre. On the threaded blocks a set of V-blocks are
mounted to clamp the open end of the U-tube. Equal clamping makes the axis of
the U-tube in line with machine axis.
The Steady rest means comprises a weldment that is to be mounted on the
machine bed. The Weldment houses four bearing assemblies on which a ring
assembly rotates freely with the ring assy axis coinciding with the machine axis.
Inside the ring assembly, a rest plate is mounted with an adjustable screw rod
for resting the U tube and to align it with the machine axis. Two adjustable
screws are provided onto the ring assy for side adjustment of the U Tube. For
adjusting and aligning, the existing branch tube holder is made use of.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The proposed invention will be better understood by the following description
with reference to the accompanying drawings:
Figure 1 Shows an U-tube holder according to the prior art.
Figure 2 Shows a branch tube holder according to the prior art.
Figure 3 Shows an equally moving v-block assembly for clamping open end
of the U-tube according to the invention.
Figure 4 Shows a steady rest for adjusting and clamping bend end of the U-
tube according to the invention.
Figure 5 Shows the device of the invention in an operational mode.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
As shown in figure 3, the V-block assembly comprises a base plate(35)
connectable to the machine face plate a guide plate(39), a Screw rod (44)
mounted on to the guide plate (39) by a first block (40) including a second block
(43). One each threaded block RH(45), and threaded block LH(46) is caused to
move inward and outward by the screw rod(44), and a set of V-block (47) fixed
on the threaded blocks(45&46) for clamping an open end of the U-tube.
As shown in figure 4, the rest assembly comprises a Weldment(53) mountable
on to the machine bed that accommodates at least two bearing assembly
(58,64) a ring assy(73) that is made to rotate on the first bearing assy (58) in
line with the machine axis. The second bearing assy (64) with an eccentric pin
firmly holding the ring assy (73) against the first bearing assy (58). A screw rod
(77) is mounted inside the ring assy(73). A rest plate(79) is mounted on to the
screw rod(77) with a plurality of guide pins(80) screwed at the ends of the rest
plate (79) to prevent rotation of the rest plate while adjusting the height. An
adjustable screw(84) for side way adjustment of the U-tube, and a clamp
plate(82) with a c-washer(83) with a nut (91) mounted on a stud(81) are
provided for quick clamping of the U-tube.
WE CLAIM
1. A device in an welding machine for welding of bifurcate objects installed
on power boilers, comprising:
- a holding means configured into two segments, the first segment
constitutes a movable V-block assembly, and allows the U-tube to be
aligned to the machine axis, the second segment comprising a rest
assembly having a weldment mounted on the machine bed, and
- a branch tube holder disposed on the machine bed and clamped between
the bearings disposed on the second segment for adjusting and
alignment.
2. The device as claimed in claim 1, wherein the first segment comprises a
base plate connectable to the machine face plate; a screw rod mounted
on a guide plate by a block assembly having a first and a second block;
and a plurality of V-blocks fixed on a right hand and a left hand threaded
block, the threaded blocks being inwardly and outwardly movable by the
screw rod for clamping an open end of the U-tube.
3. The device as claimed in claim 1, wherein the weldment accommodates at
least two bearing assembly, first bearing assembly allowing a ring
assembly to rotate in line with the machine axis, the second bearing
assembly holding the ring assembly with an eccentric pin against the first
bearing assembly; a screw rod having a rest plate with a plurality of guide
pins to prevent rotation of the rest plate during height adjustment of the
object.
4. The device as claimed in any of the preceding claims, comprising an
adjustable screw for side way adjustment of the U-tube, and a clamp plate
with c-washers for clamping of the U-tube.

The invention relates to a device in an welding machine for welding of
bifurcate objects installed on power boilers, comprising: a holding means
configured into two segments, the first segment constitutes a movable V-block
assembly, and allows the U-tube to be aligned to the machine axis,
the second segment comprising a rest assembly having a weldment
mounted on the machine bed, and a branch tube holder disposed on the
machine bed and clamped between the bearings disposed on the second

segment for adjusting and alignment.