Note: Descriptions are shown in the official language in which they were submitted.
~1194)90
This invention is concerned with apparatus for perforating
tubing. Such tubing which may be of a thermoplastic material
such as r for example, polyethylene, may be used as underground
drainage piping, water operatively percolating into the tubing
through the perforations therein for drainage along the tubing.
It has hitherto been proposed to form the perforations in such
tubing by passing the unperforated tubing after its formation
in, for example, a blow-moulding apparatus to an apparatus in
which rotary cutter means is engaged with the walls of the
tubing to form the required perforations. Such apparatus is
disclosed in U.S. patent No. 3,957,386 issued on May 18, 1976
and in Canadian patent application No. 260,094 filed on
August 27, 1976. The forms of apparatus disclosed in the above-
numbered United States patent and Canadian patent application
are, however, relatively complex, and it is accordingly a
primary object of one aspect of the present invention to provide
apparatus for perforating tubing which substantially obviates
or mitigates the above disadvantage of the forms of apparatus
disclosed in the above-numbered United States patent and
1:~19(~90
-- 2
Canadian patent application in that it is relatively simple
and as a result very dependable in operation.
According to this one aspect of the present invention there is
provided apparatus which comprises drive means for advancing
tubing along an axial path thereof, and at least one cutter
rotatably mounted in a rotary path which intersects the tubing
and which is in a plane substantially at right angles to said
axial path of the tubing for intermittent intersection of the
- tubing by the cutter. The mounting of the cutter permits move-
ment of the cutter by the tubing in a direction parallel to said
axial path from a rearward position to a forward position
during operative intersection of the tubing by the cutter. The
apparatus further comprises a return member for movement of the
cutter from the forward position to the rearward position between
operative intersections of the tubing by the cutter, and support
means for supporting the tubing and restraining the tubing
against rotation thereof about said axiaLpath during operative
intersectinn~of th~ tu~ing by the cutter.
The present invention is also concerned with a method of
perforating tubing, and it is a primary object of a further
aspect of the invention to provide such a method.
According to this further aspect of the present invention
there is provided a method of perforating tubing, the method
comprising the steps of advancing the tubing along an axial
path thereof, and simultaneously rotating at least one cutter
in a rotary path which is in a plane substantially at right
angles to said axial path of the tubing and which intersects
the tubing thereby to perforate the tubing by intermittent
intersection of the tubing by the cutter, while the cutter is
being moved by the tubing in a direction parallel to said
axial path from a rearward position to a forward position
thereof. The method further comprises returning the cutter
from the forward position to the rearward position between
operative intersections of the tubing by the cutter, the tubing
'... ' 1119090
-- 3 --
being supported and being restrained against rotation thereof
about said axial path during intersection of the tubing by the
cutter.
In order that the present invention may be more clearly
understood and more readily carried into effect the same will
now, by way of example, be more fully described with reference
to the accompanying drawings in which:
Fig. 1 is a view of apparatus for perforating tubing;
Fig. 2 is a sectioned side view, on an enlarged scale, generally
on the line 2-2 in Fig. l;
Fig. 3 is a sectioned end view on the line 3-3 in Fig. 2;
Fig. 4 is a sectioned view on the line 4-4 in Fig. 2;
Fig. 5 is a sectioned view, on a further enlarged scale, on
the line 5-5 in Fig. 4;
Fig. 6 is a view, on a still further enlarged scale, of part
of the apparatus shown in the preceding views;
Fig. 7 is a sectioned view on the line 7-7 in Fig. 6;
Fig. 8 is a side view of the part of the apparatus shown in
Fig. 6, but according to an alternative embodiment of the
invention;
Fig. 9 is a view of a part of the apparatus according to a
still further embodiment of the invention;
Fig. 10 is a view showing a feature of the apparatus;
Fig. 11 is a side view of a portion of perforated tubing
produced by the apparatus;
~1~9C)90
-- 4 --
Fig. 12 is a sectioned view on the line 12-12 in Fig. 11;
Fig. 13 is a side view of a portion of perforated tubing
produced by apparatus part of which is shown in Fig. 8;
Fig. 14 is a partially sectioned side view corresponding to
a portion of Fig. 2, but showing a different form of apparatus
for perforating tubing;
Fig. 15 is an isometric view of part of the apparatus shown
in Fig. 14;
Fig. 16 is a view of part of the apparatus shown in Figs. 14
and 15;
Fig. 17 is a sectioned view on the line 17-17 in Fig. 16;
Fig. 18 is a view corresponding to Fig. 16 of a portion of
the apparatus shown therein according to a modified form
thereof;
Fig. 19 is a view of part of the apparatus shown in the
preceding views, but according to a yet still further embodi-
ment of the invention;
Fig. 20 is a view corresponding to Fig. 19, but showing the
part of the apparatus illustrated therein according to a
modified form thereof;
Fig. 21 is a partially sectioned side view corresponding to
a portion of Fig. 2, but showing'apparatus according to a
preferred embodiment of the present invention;
Fig. 22 is a sectioned view on the line 22-22 in Fig. 21;
Fig. 23 is a partially sectioned side view corresponding to
Fig. 21, but showing an alternative form of the preferred
~ ~ '
.
:,: .. ; - ~ ,
. ~il9V9O
. ,
-- 5
embodiment shown therein;
Fig. 24 is a partially sectioned side view corresponding to
Figs. 21 and 23, but showing an alternative preferred
embodiment of the present invention; and
Fig. 25 is a sectioned view on the line 25-25 in Fig. 24.
Referring to Figs. 1 to 13, inclusive, of the drawings, the
apparatus comprises a frame structure constituted, in the
preferred embodiment of the invention, by two spaced end
housings 10 and 11 which have coaxially disposed central
openings 12 through which tubing 13, which may be of thermo-
plastic material, is operatively advanced in the direction of
the arrow A (Fig. 1), as is hereinafter described. Each of
the end housings 10 and 11 comprises a body member 14, and an
end cover 15 which is secured to the associated body member 1
by, for example, bolts 16, each body member 14 presenting a
base 17 which is adapted to be secured to a support surface
by means of bolts 18.
The apparatus further comprises drive means for advancing the
tubing 13 along the axial path A thereof, this drive means
comprising, in the preferred embodiment shown in the drawings,
a plurality of lead screw members 19 having screw threading 20
for meshing engagement with corrugations 21 presented by the
tubing 13. The lead screw members 19 which are disposed
substantially parallel to the axial path A of the tubing 13
and which extend between the end housings 10 and 11 are each
rotatably mounted in these end housings 10 and 11, the end
portions of the lead screw members 19 which are rotatably mounted
in the end housing 10 being so mounted by means of ball bearings
which are denoted generally by the reference numberals 22 and
which may be of conventional form, and the end portions of the
lead screw members 19 which are rotatably mounted in the end
housing 11 being so mounted by means of roller bearings which
are denoted generally by the reference numberals 23 and which
.. 1~19~90
..
may likewise be of conventional form.
A gear wheel 24 is screw-threadedly mounted on the end portion
of each lead screw member 19 within the end housing 11 and is
locked by a nut 25. A drive shaft 26 which is disposed sub-
stantially parallel to the axial path A is journalled in thebody members 14 of the end housings 10 and 11 by means of roller
bearings which are denoted generally by the reference numberals
27 and which may again be of conventional form, the end portion
of the shaft 26 within the end housing 11 having a gear wheel
28 keyed thereto, and the opposed end portion of the shaft 26
extending through an opening in the end cover 15 of the housing
10 and projecting therefrom for connection to an appropriate
drive means (not shown) for operatively rotating the drive
shaft 26.
As is most clearly shown in Fig. 3, the gear wheel 28 operatively
drives the gear wheels 24 of all the lead screw members 19
through idler gears 29, 30, 31, 32, 33, 34 and 35. More parti-
i cularly, the lead screw members 19 are disposed in pairs, with
the lead screw members 19 of each pair thereof preferably being
diametrically opposed relative to the axial path A. Thus, withreference to the preferred embodiment of the invention, the pairs
of lead screw members 19 are constituted by the members l9A and
l9A', l9B and l9B', l9C and l9C', and l9D and l9D', the gear
wheels 24 of the members l9A and l9B being operatively driven in
the same direction directly by the gear wheel 28, the gear wheel
24 of the member l9C being operatively driven in said same
direction by the idler gear wheel 30 which is driven by the gear
wheel 24 of the member l9B, and the gear wheel 24 of the member
19~ being operatively driven again in said same direction by
the .idler gear wheel 29 which is driven by the gear wheel 24 of
the member l9C. The gear wheel 24 of the member l9D' is
operatively driven but in the opposite direction through the
-two idler gear wheels 31, 32 from the gear wheel 24 of the member
l9A, the gear wheel 24 of the member l9C' is operatively driven
in said opposite direction by the idler gear wheel 33 which is
:
1119~90
-- 7 --
driven ~y the gear wheel 24 of the memher l9D', the gear wheel
24 of the member 19B' is operatively driven again in said
opposite direction by the idler gear wheel 34 which is driven
by the gear wheel 24 of the member 19C', and the gear wheel 24
of the member l9A' is operatively driven once again in said
opposite direction by the idler gear wheel 35 which is driven
by the gear wheel 24 of the memher 1~'. The screw threading
20 of the lead screw mem~ers 1~ of each pair thereof is of
opposite hand.
With reference to Figs. 1 to 13, inclusive, there is mounted
on each of the lead screw members 19 a cutter 36 which is
operatively moved with the associated lead screw member 19 only
in a fixed rotary path of circular form which is thus in a plane
substantially at right angles to the axial path A and which
intersects the tubing 13 thereby to perforate the tubing 13 as
is hereinafter more fully described, each cutter 36 being
outwardly directed relative to said rotary path thereof. There
may of course be more than one cutter 36 mounted on each of the
lead screw members 19.
As lS most clearly shown in Figs. 5, 6 and 7, each cutter 36
comprises an inner shank portion 37 together with an outer
cutting portion 38 having a concave leading edge 39 which con-
stitutes a cutting edge and is preferably of V-shape in cross-
section as shown in Fig. 7 and which terminates at the end of
the cutting portion 38 remote from the shank portion 37 in a
cutting point 40. The shank portion 37 of the cutter 36 is
disposed within a slot 41 which is formed in a plug 42, the plug
42 being removably mounted in a recess 43 within the associated
lead screw member 19 by means of a screw member 44 which is
screw-threadedly engaged with the plug 42. The shank portion
37 of the cutter 36 is securely clamped in the slot 41 under the
influence of the interengagement between the plug 42 and the
walls of the recess 43. Thus, for example, in the preferred
embodiment of the invention shown in the drawings~ the plug 42 is
of tapered form so that as the plùg 42-is urged into the recess
. .
195~'~0
43 on tightening of the screw member 44 the width of the slot 41
is reduced with resultant clamping of the shank portion 37 of
the cutter 36 in the slot 41.
Fig. 8 shows an alternative embodiment which differs from that
described above with reference to Figs. 5, 6 and 7 in that there
are two cutters 36 disposed within the slot 41 in the plug 42,
the two cutters 36 being separated by a spacer member 45.
Fig. 9 shows an alternative form of cutter 36 which is formed of
a strip of metal which is reflexly bent with the contacting
side-by-side end portions of the strip constituting the shank
portion 37 of the cutter 36, the cutting portion 38 being in
the form of a loop 46 having a leading edge 47 which is sharpened
to provide a cutting edge.
In operation, the drive shaft 26 is rotatably driven with, as
lS hereinbefore described, resultant rotation of the lead screw
members 19 in the directions shown in Fig. 3. The screw threading
20 of the members 19 is in meshing engagement with the corruga-
tions 21 of the tubing 13 so that said rotation of the lead screw
members 19 causes advancement of the tubing 13 along the axial
path A.
Said rotation of the lead screw members 19 also, of course,
causes rotation of each cutter 36 in its rotary path, and as
each cutter 36 intermittently intersects the tubing 13 the tubing
is thereby perforated. Fig. 4 shows the operative condition in
which the cutters 36 mounted on the pair of lead screw members
l9A and l9A' are perforating the tubing 13. The cutters 36
mounted on each said pair of the lead screw members 19 are
synchronized for substantially simultaneous intersection with
the tubing 13 and since these cutters 36 rotate in opposite
directions they operatively exert on the tubing 13 during
perforation of the tubing 13 substantially equal but opposite
forces. Thus, these cutters 36 mounted on each said pair of
the members 19 constitute means for restraining the tubing 13
~i9(~90
g
against rotation during operative intersection of the tubing 13
by these cutters 36. Furthermore, the lead screw members 19,
together with annular portions 43 of the body members 14 of the
end housings 10 and 11, constitute support means for supporting
the tubing 13.
Figs. 11 and 12 show the perforations 49 in the perforated
tubing 13 produced by the apparatus as hereinbefore described,
Fig. 13 showing the form of the perforations 49 produced by
the alternative embodiment described above with reference to
Fig. 8. In order, as shown in Fig. 10, to alter the lengths
of the perforations 49 produced in the tubing 13 the distance
to which each cutter 36 outwardly projects from the associated
lead screw member 19 is preferably adjustable, this being
readily achieved by altering the position of the shank portion
37 of each cutter 36 within the slot 41 of the associated plug
42.
It will be appreciated that the minimum circumferential spacing
between adjacent perforations 49 in the tubing 13 is dependent
on the minimum spacing which is possible between adjacent ones
of the lead screw members 19, and if desired there may be
provided, in combination, a plurality of apparatuses as herein-
before described in which the apparatuses are disposed with the
axial paths A thereof in alignment, the cutters 36 of each of
the apparatuses being in non-alignment, as viewed in the direction
of said axial paths A, with the cutters 36 of each of the other
of the apparatuses. In this manner, there may be provided
perforations 49 in the tubing 13 between perforations 49 which
are circumferentially spaced apart the minimum possible distance
when using one apparatus.
Each lead screw member 19 as hereinbefore described may be formed
by drilling or otherwise forming the recess 43 in the cylindrical
wall of a cylindrical member, and then mounting the plug 42
within this recess 43 by means of the screw member 44 the head
of which is deeply recessed into the cylindrical wall of the
lil~V~
-- 10 --
cylindrical member. The screw threading 20 is then machined
or otherwise formed on the cylindrical wall of the cylindrical
member while the plug 42 remains mounted in the recess 43.
Thereafter, the slot 41 is formed in the plug 42 by, most
conveniently, first removing the plug 42 from the recess 43,
and the associated cutter 36 is then mounted within the slot 41
and the plug 42 is remounted within the recess 43 by means of
the screw member 44, as hereinbefore described.
It is generally preferred that the perforations 49 in the
tubing 13 be provided in the valleys between the corrugations
21, so that each cutter 36, and the associated plug 42, are
preferably disposed at the crest of the fluting of the screw
threading 20. It will, however, be appreciated that if it is
desired to form some or all of the perforations 49 in the
corrugations 21 of the tubing 13 rather than solely in the
valleys between these corrugations 21 the appropriate cutter or
cutters 36, and the associated plug or plugs 42, can of course
be disposed between the fluting of the screw threading 20.
Except as hereinafter described the formsof the apparatus
illustrated in Figs. 14 to 20, inclusive, correspond to the
apparatus as hereinbefore described with reference to Figs.l to
7, inclusive, 10, 11 and 12 of the drawings, and in Figs~ 14 to
20, inclusive, like reference numerals are used as in Figs. 1
to 7, inclusive, 10, 11 and 12 to denote like parts.
In the apparatus as hereinbefore described with reference to
Figs. 1 to 7, inclusive, 10, 11 and 12 the screw threading 20 on
each lead screw member 19 extends continuously along the lead
screw member 19 so that the tubing 13 operatively continues its
advance along the axial path A thereof during the intersection
o the tubing 13 by the cutter or cutters 36. This results, of
course, in each perforation 49 which is thus formed in the tubing
13 being disposed in a direction having a component parallel to
the axial path A of the tubing 13, rather than the perforation 49
being disposed in a direction which is truly circumferential
~119~;)90
around the tubing 13. In many cases this feature will be quite
acceptable, ~ut in some cases this feature may be undesirable and
there is accordingly also provided apparatus for perforating
tubing in which the perforations operatively formed in the
tubing by the apparatus are each circumferentially disposed,
together with a method of per~orating tubing in which the per-
forations formed in the tubing are each circumferentially
disposed. Thus, referring to Figs. 14 and 15 it will be noted
that a central portion 50 of each lead screw member 19 i5 devoid
of the screw threading 20, this portion 50 presenting a plurality
of, say, three axially spaced ribs 51 which are each circum-
ferentially disposed and are axially spaced from the adjacent
screw threading 20. Furthermore each rib 51 extends only
partially around the circumference of the lead screw member 19.
During operative rotatable driving of the drive means comprising
the lead screw members 19 with resultant advance of the tubing 13
along the axial path A thereof, as hereinbefore described, the
ribs 51 of each lead screw member 19 enter into meshing engage-
ment with the corrugations 21 of the tubing I3, as is clearly
shown in Fig. 14, at least the leading ends of the ribs 51
preferably being of tapered width to facilitate this entry of
the ribs 51 into meshing engagement with the corrugations 21 of
the tubing 13. While the ribs 51 are so meshingly engaged with
the corrugations 21 of the tubing 13 the associated part of the
tubing 13 is restrained against advance along the axial path A
thereof, and during this meshing engagement of the ribs 51 with
- the corrugations 21 of the tubing 13 the cutter 36 intersects
said associated part or intersected part of the tubing 13 to
perforate the tubing 13, the cutter 36 preferably being mounted
on one of the ribs 51 such as the central rib Sl for operative
rotation therewith. Thus, since advance of at least the inter-
sected part of the tubing 13 along the axial path A thereof
during the intersection of the tubing 13 by the cutter 36 is
stopped by, with reference to Figs. 14 and 15, means constituted
by the ribs 51 restraining the intersected part of the tubing 13
against said advance, it will be appreciated that the perforation
~119~)90
- 12 -
49 which is thereby formed in the tubing 13 is disposed in a
truly circumferential direction.
The axial spacing between the ribs 51 of each lead screw member
19 and the adjacent screw threading 20 thereof accommodates
resilient deformation of the tubing 13 in the direction of the
axial path A thereof during the meshing engagement of the ribs
51 with the corrugations 21 of the tubing 13, the tubing 13
being so resiliently deformable by, for example, being formed
of a thermoplastic material such as polyethylene, as herein-
before described. Thus, it will be appreciated that, duringthe meshing engagement of the ribs 51 of each lead screw member
19 with the corrugations 21 of the tubing 13, the screw threading
20 of the lead screw member 19 on either side of the ribs 51
continues to advance the tubing 13 along the axial path A thereof
with resultant resilient extension of the tubing 13 in the
portion of the tubing 13 between the ribs 51 and the screw
threading 20 which is in advance of the ribs 51 relative to the
direction of the axial.path A, and with resultant resilient
compression of the tubing 13 in the portion af the tubing 13
between the ribs 51 and the screw threading 20 which is behind
the ribs 51 relative to the direction of the axial path A. As
herein described with reference to Figs. 14 and 15, the portion
50 of each lead screw member 19 is centrally disposed with screw
threading 20 in advance of and behind the portion 50, but it
will of course be appreciated that if this portion 50 of the lead
screw member 19 is disposed at the forward end of the lead screw
member 19 with screw threading 20 only behind this portion 50
the tubing 13 need of course only be resiliently compressible,
while conversely if the portion 50 is disposed at the rearward
end of the lead screw member 19 with screw threading 20 only in
advance of this portion 50 the tubing 13 need of course only be
resiliently extendible.
The ribs 51 extend around the as50ciated lead screw member 19 to
an extent sufficient to ensure that these ribs 51 are in meshing
engagement with the corrugations 21 of the tubing 13 throughout
,, . ., ~ . . . . . .. . .. .. . .. . .... . .. . ..
1119090
- 13 -
the entire-ty oE the intersection of the tubing 13 by the cutter
36, and thus the extent of the ribs 51 around the circumference
of the lead screw member 19 is dependent on the length of the
perforations 49 formed in the tubing 13 by the cutter 36.
Typically, the ribs 51 may extend around approximately one
quarter of the circumference of the lead screw member 19,
although it will be noted that as shown in Fig. 15 the central
rib 51 on which the cutter 36 is mounted may be of reduced
length.
As the ribs 51 disengage from the corrugations 21 of the tubing
13 the above-described resilient deformation of the tubing 13 is
of course relieved.
Although as hereinbefore described the portion 50 of the lead
- screw member 19 is provided with a plurality of the ribs 51 this
portion 50 may in alternative embodiments (not shown) be provided
with only one such rib 51.
Referring now to Figs. 16 and 17, the rib 51 on which the cutter
36 is mounted may be provided with an open-ended bore 52 which
is circumferentially formed through the portion of said rib 51
between the leading end of said rib 51 and the recess 43, one
end of the bore 52 thereby communicating with the concave leading
edge 39 at the end thereof remote from the cutting point 40, so
that as the cutter 36 operatively intersects the tubing 13 as
shown in Fig. 17 the leading end of the chip 53 which is removed
from the tubing 13 to form a perforation 49 therein is directed
into the bore 52 for discharge of the chip 53 therethrough. This
substantially prevents the trailing end of the chip 53 from
remaining attached to the tubing 13 after the intersection of the
tubing 13 by the cutter 36 has been completed.
Figure 19 shows a further embodiment in which the cutter 36 is
integrally formed with the plug 42, an open-ended bore 54 the
function of which corresponds to that of the bore 52 being
. . l~i9~)90
,~ 1~ --
provided therethrough for the discharge of the chips 53.
Figs. 18 and 20 show co~respondingly modified forms of the
structures illustrated in Figs. 16 and 17 and in Fig. 19, -
respectively, in which a side 55 of each bore 52 and 54 is open
in a direction transverse to the plane containing the rotary
path of the cutter 36 for facilitating clearing of the chips
53, thereby to avoid any risk of these chips 53 clog~ing the
bore 52 or 54, respectively.
Except as hereinafter described each apparatus according to
the preferred embodiments of the present invention illustrated
in Figs. 21 to 25, inclusive, corresponds to the apparatus as
hereinbefore described with particular reference to Figs. 14
and 15, and in Figs. 21 to 25, inclusive, like reference
numerals are used as in Figs. 14 and 15 to denote like parts.
As hereinbefore described with reference to Figs. 14 and 15
there is pro~ided apparatus for perforating tubing in which the
perforations operatively formed in the tubing by the apparatus
are each circumferentially disposed, together with a method of
perforating tubing in which the perforations formed in the tubing
are each circumferentially disposed. However, it is a require-
ment of this apparatus and method as hereinbefore described with
reference to Figs. 14 and 15 that the tubing 13 be of a material
which is resiliently deformable, but in some cases it may be
desired that the tubing 13 be of a material which is not
resiliently deformable, or at least which is not sufficiently
resiliently deformable for satisfactory functioning of the
apparatus and method as hereinbefore described with reference to
Figs. 14 and 15, and there is accordingly also provided apparatus
for perforating tubing in which the perforations operatively
formed in the tubing by the apparatus are each circumferentially
disposed, together with a method of perforating tubing in which
the perforations formed in the tubing are each circumferentially
disposed, even where the tubing is of a material which is not
resiliently deformable.
~19~)90
- 15 -
Thus, reEerring to Figs. 21 and 22 it will be noted that the
central portion 50 of each lead screw member 19 and which is
devoid of the screw threading 20 is of reduced diameter, a
slide member 56 constituted preferably by a sleeve being
slidably and non-rotatably mounted on the portion 50 of the
lead screw member 19. Preferably this slidable and non-
rotatable mounting of the sleeve 56 on the portion 50 of the
lead screw member 19 comprises a splined connection between
the sleeve 56 and the portion 50, this splined connection
being constituted by one or more longitudinally extending,
outwardly directed splines 57 which are presented by the
portion 50 and which are each slidably disposed within a
complementary groove 58 provided in the inner face of the
sleeve 56. As will be noted from Figs. 21 and 22 there are
in the preferred embodiment illustrated therein four equi-
angularly disposed splines 57 and complementary grooves 58.
The cutter 36 is mounted on a circumferentially disposed rib 64
which is presented by the sleeve 56 and which extends only
partially around the sleeve 56, the sleeve 56 being slidable on
the portion 50 of the lead screw member 19 in a direction
parallel to the axial path A of the tubing 13 between a rear-
ward position of the cutter 36 and the sleeve 56 (the position
in which the sleeve 56 is shown in full lines in Fig. 21) and
a forward position of the cutter 36 and the sleeve 56 (the
position in which the right-hand end of the sleeve 56 is shown
in chain-dotted lines in Fig. 21), and bearing rings 59 being
mounted in the ends of the sleeve 56 for sliding contact with
the portion 50 of the lead screw member 19. Preferably, the
portion 50 is provided with a recess 60 within which is disposed
a coil spring 61 and a ball 62 which is urged by the spring 61
out of the recess 60 into a detent 63 provided in the inner
face of the sleeve 56 when the sleeve is in the rearward position,
resiliently to restrain the sleeve 56 in this rearward position.
During operative rotation of each lead screw member 19 with
resultant advancing of the tubing 13 along the axial path A
- 16 -
thereof the rib 64 enters into meshing engagement with the
corrugations 21 of the tubing 13 as the sleeve 56 rotates with
the screw member 19, the leading end of the rib 64 preferably
being of tapered form to facilitate this entry of the rib 64
into meshing engagement with the corrugations 21 of the tubing
13. While the rib 64 is so meshingly engaged with the corruga-
tions 21 of the tubing 13 the cutter 36, together of course with
the sleeve 56, is thereby moved with the tubing 13 from the
above-mentioned rearward position to the forward position so
that during the intersection of the tubing 13 by the cutter 36
there is substantially no relative movement between the tubing
13 and the cutter 36 in the direction of the axial path A with
the result that the perforations formed in the tubing 13 by the
cutter 36 are circumferentially disposed.
The apparatus also comprises a return member for movement of the
cutter 36, and of the sleeve 56, from the above-mentioned
forward position to the rearward position, this return member
in the preferred embodiment of the invention shown in Figs. 21
and 22 comprising a helically disposed rib 65 which is presented
by the sleeve 56 and which extends only partially around the
slide member 56, the pitch of this helically disposed rib 65
which as will be noted may constitute a continuation of the rib
64 being such that, after completion of the intersection of the
tubing 13 by the cutter 36 and disengagement of the rib 64 from
the corrugations 21 of the tubing 13, the rib 65 under the
influence of the corrugations 21 of the tubing 13 meshingly
engaged therewith operatively urges the sleeve 56 and hence also
the cutter 36 back to the rearward position in which the ball
62 is resiliently re-engaged with the detent 63.
The form of the invention shown in Fig. 23 differs from the
preferred embodiment hereinbefore described with reference to
Figs. 21 and 22 only in that, whereas in the preferred embodiment
shown in Figs. 21 and 22 the helically disposed rib 65 constitutes
a continuation of the rib 64 extending from the trailing end
thereof so that the cutter 36 and the sleeve 56 are operatively
9o~o
- 17 -
returned to the rearward position immediately after completion
of the intersection of the tubing 13 by the cut~er 36, in the
alternative form shown in Fig. 23 the helically disposed rib
65 constitutes a continuation of the rib 64 from the leading
end thereof so that in this alternative embodiment the cutter
36 and the sleeve 56 are returned to the rearward posi~ion
immediately preceding the intersection of the tubing 13 by the
cutter 36. Furthermore, in Fig. 23 the leading end of the rib
65 instead of the leading end of the rib 64 is preferably of
tapered form, to facilitate entry of the rib 65 into meshing
engagement with the corrugations 21 of the tuhing 13. In Fig.
23 the sleeve 56 is shown in full lines in the forward position
of the cutter 36, with the left-hand end of the sleeve 56 being
shown in chain-dotted lines when the cutter 36 is in the rear-
ward position thereof.
The alternative preferred embodiment of the present invention
shown in Figs. 24 and 25 differs from that hereinbefore des-
cribed with reference to Figs. 2-1 to-23, inclusive, in that in
Figs. 24 and 25 each lead screw member 19 is constituted by two
spaced portions, with the slide member constituted by an insert
member 66 the end portions of which present splines 67 slidably
and non-rotatably disposed within complementary grooves 68
provided in the walls of recesses 69 in the adjacent ends of
the two spaced portions of the lead screw member 19. 70 denotes
each of two annular seals which are mounted on the end portions
of the insert member 66 for sealing contact with the walls of
portions of the recesses 69 of increased diameter.
Furthermore, in Figs. 24 and 25 the rib 64 of the embodiment of
Figs. 21 to 23, inclusive, is replaced by two axially spaced
circumferentially disposed ribs 71 which extend only partially
around the insert member 66 and between which the cutter 36 is
mounted on the insert member 66. Also, instead of the helically
disposed rib 65 of the embodiment shown in Figs. 21 to 23,
inclusive, there is provided in the embodiment shown in Figs. 24
and 25 a coil spring 72 which acts between the insert member 66
. 1~19~)90
- 18 -
and one of the por-tions of the lead screw member 19 resiliently
to urge the insert member 66 in the direction from the forward
position of the cutter 36 and the insert member 66 (in which the
right-hand end of the insert member 56 is shown in chain-dotted
lines) to the rearward position thereof (in which the insert
member 66 is shown in full lines). In this rearward position the
insert member 66 abuts against the end face of the appropriate
portion of the lead screw member 19, so that in this embodiment
shown in Figs. 24 and 25 the recess 60, spring 61, ball 62 and
detent 63 shown in Figs. 21 and 23 are omitted. Each of the two
spaced portions of the lea~ screw member 19 may be provided with
a bore 73, a bore 74 also being provided through the insert member
66 between the ends thereof, so that lubricating oil may opera-
tively be supplied through these bores 13 and 74 and through the
recesses 69 in order to lubricate the splined connection consti-
tuted by the splines 67 and the complementary grooves 68.
As will be appreciated the operation o~ the alternative embodi-
ment of the invention shown in Figs. 24 and 25 is substantially
the same as that hereinbefore described with reference to the
preferred embodiment shown in Figs. 21 to 23, inclusive.
As will be appreciated the rib 64 (Figs. 21, 22 and 23) and the
ribs 71 (Figs. 24 and 25) extend around the sleeve 56 (Figs. 21,
22 and 23) and around the insert member 66 (Figs. 24 and 25) to
an extent sufficient to ensure that this rib 64 and ribs 71 are
in meshing engagement with the corrugations 21 of the tubing 13
throughout the entirety of the intersection of the tubing 13 by
the cutter 36, and thus the extent of the rib 64 around the
sleeve 56 (Figs. 21, 22 and 23) and of the ribs 71 around the
insert member 66 (Figs. 24 and 25) is dependent on the length of
the perforations 49 formed in the tubing 13 by the cutter 36.
While as hereinbefore described the rib 64 (Figs 21, 22 and 23)
or the ribs 71 (Figs. 24 and 25) operatively meshingly engage
with the corrugations 21 of the tubing 13 to move the sleeve 56
and the cutter 36 (Figs. 21, 22 and 23) or the insert member 66
' ` ' 1~19090
-- 19 --
and the cutter 36 (Figs. 24 and 25) from the rearward position
to the forward position, it will be understood that these ribs
64 or 71 could be omitted with the sleeve 56 and the cutter 36
~Figs. 21, 22 and 23) or the insert member 66 and the cutter 36
(Figs. 2~ and 25) being moved by the tubing 13 from the rear-
ward position to the forward position by the engagement of the
cutter 36 with the tubing 13 during intersection of the tubing
13 by the cutter 36. More than one cutter 36 may of course be
mounted on the sleeve 56 (Figs. 21, 22 and 23) or on the insert
member 66 (Figs. 24 and 25). Furthermore, instead of the
helically disposed rib 65 ~Figs. 21, 22 and 23) or the coil
spring 72 (Figs. 24 and 25) alternative means (not shown) could
be provided for returning the cutter 36, and the sleeve 56 or
the insert member 66, from the forward position to the rearward
position. Thus, for example, a plunger acting on the sleeve
56 or the insert member 66 could be provided, this plunger rod
being actuated by for example a rotary cam face the rotation
of which is appropriately timed relative to the rotation of the
lead screw member 19 to move the sleeve 56 so the insert member
66 from the forward position to the rearward position between
intersections of the tubing 13 by the cutter 36. Alternatively,
an end edge of the sleeve 36 or of the insert memb~ 66 could
be provided with an appropriately shaped cam face bearing
against a fixed member, so that as the sleeve 56 or the insert
member 66 operatively rotate the bearing contact between the
fixed member and the cam face causes the sleeve 56 or the insert
member 66 to move from the forward position to the rearward
position between intersections of the tubing 13 by the cutter 36.
While in the apparatus as hereinbefore described with reference
to the accompanying drawings, the drive means for advancing the
tubing 13 along the axial path A comprises the plurality of
lead screw members 19 it will be appreciated that in alternative
embodiments (not shown) there may be provided only one lead
screw member 19 for advancing the tubing 13 along the axial
path A, or other means may be provided for advancing the tubing
... . . . , . ... . ., . ..... .. . . _ .. .. .. . ... . .. . . . . . .. .
g 90
- 20 -
13 which need not be of corrugated Eorm, along the axial path A.
Where the tublng 13 is of corruga-ted form said other means may
comprise for example a rotatably drivable gear wheel the axis
of rotation o~ which is at riyht angles to the axial path A
and the teeth of which engage with the corrugations 21 of the
tubing 13.
Furthermore, the apparatus may incorporate any number of
cutters 36 each mounted for rotation in a circular rotary
path which intersects the tubing 13 and which is in a plane
substantially at right angles to the axial path A, including
only a single such cutter 36. If, of course, the number and
disposition of the cutters 36 is such that cutters 36 of a
pair thereof do not substantially simultaneously intersect
the tubing 13 while rotating in opposite directions alter-
native means is provided for restraining the tubing 13 againstrotation thereof about the axial path A during operative
intersection of the tubing 13 by the cutter ar cutters 36. In
addition, if the drive means for advancing the tubing 13 along
the axial path A~is c~ns~tituted-by ~theL.than the lead screw
members 19 alternative support means may be required for
supporting the tubing 13 between the end housings 10 and 11.
