Method of and apparatus for cutting tubes

A method and apparatus for cutting a tube, preferably provided with a hard surface, into pieces which involves first subjecting the coated tube to the grinding action of a disk to remove a narrow band of coating and to effect a shallow groove in the tube prior to contacting the bottom of the groove with a cutting knife to slice the tube into pieces having ends which are essentially planar and perpendicular to the longitudinal axis of the pieces. The knife and grinding disc may be mounted on reciprocally movable carriages. The movable carriage supporting the grinding disc is preferably mounted on an adjustment rod so as to permit precise spacing relative to the exterior surface of the tube. The grinding disc is controlled to prevent it from contacting a mandrel supporting the tube.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a device for cutting cylindrical tubes 
into tubes pieces. The cutting device of the present invention is 
particularly suitable for cutting predetermined lengths of tube pieces 
from a continuously formed spiral tube made from strips of cellulosic 
material, such as cardboard or paper, which has been provided with a 
coating of substance which forms a hard surface on at least a portion of 
the exterior of the tube. 
2. Discussion of Background and Material Information 
Cylindrical tubes may be formed from various materials such as cellulosic 
strips, and treated in different ways depending on their intended use. For 
example, cardboard tubes may be provided with a hard surface coating which 
is substantially uniform across their entire surface or only on a portion 
thereof as required by the situation. 
It is conventional to form tubes in a continuous fashion on machines known 
as spiralers by helically winding a plurality of cellulosic strips, such 
as paper or cardboard, around a mandrel. The resultant cylinder in its 
rotation is continuously advanced in a longitudinal direction towards 
cutting and polishing stations located downstream from the forming 
station. As the continuously formed tube reaches the cutting station, 
conventional severing devices are brought into play to slice or cut 
individual units of desired size from the tube, which may be further 
subdivided into appropriate sized pieces as desired. 
The apparatus used by the prior art to sever continuously formed tubes into 
pieces or to sever the said pieces, generally has at least one knife which 
cooperate with a special part of the mandrel supporting the tube or with a 
special mandrel so as to act against the tube to be cut witch is placed 
into rotation. In those instances where the cylinder to be cut is provided 
with a hard surface on at least a portion of its exterior during its 
formation, or after an initial cutting into tubular pieces, the cutting 
action of the knives of prior art apparatus often causes a disruption in 
the hard surface coating which may result in a peeling or scaling of the 
coating from the surface. It then becomes necessary to perform a 
subsequent finishing operation which may involve additional polishing in 
an attempt to repair the damaged surface. 
The present invention is directed to a method and apparatus for cutting a 
coated cylinder into tubular pieces which minimizes peeling or scaling of 
the coated surface, and hence eliminates the necessity of an additional 
finishing operation. According to the present invention, an apparatus is 
provided whereby the coated surface of the tube is subjected to an 
operation which simultaneously grinds off the surface coating in a narrow 
band around the area of the tube to be cut while buffing the same so as to 
prevent feathering, rough edges, and the tendency of the coating to scale 
or peel. To this end, the apparatus of the present invention is equipped 
not only with at least one knife for cutting the tube and an apparatus to 
rotate the tube as it is being formed, but also with a unique arrangement 
including a grindstone or polishing wheel designed to move transversely 
towards and away from the tube to a controlled degree so as to precisely 
score a peripheral groove in the coated surface of the tube around the 
area where the tube is to but cut with a cutting knife being positioned to 
finish the cut beginning at the bottom of the furrow or groove formed by 
the polishing wheel. Although the grindstone or polishing wheel and the 
knife are programmed to act successively in the foregoing manner, the 
cutting action of the knife begins almost immediately upon removal of the 
surface coating and the scoring of the groove caused by the grindstone. 
The unique arrangement of elements of the apparatus of the present 
invention also permits the tube to be polished while it is being cut as 
well as immediately afterward to result with two pieces having smooth, cut 
end surfaces. 
U.S. Pat. No. 3,711,996, BRADEN et al., discloses an apparatus which 
includes a mill wherein a plurality of rotating grinding wheels are passed 
by the peripheral surface of a mandrel on which a cylindrical cured cord 
reinforced rubber sleeve is supported in a direction perpendicular to the 
longitudinal axis of the mandrel so as to engage a sleeve to cut 
peripheral grooves in the sleeves while a plurality of rotating cutting 
blades pass the peripheral surface of the mandrel in a similar manner to 
sever the sleeve into a plurality of V-belts. Accordingly, the grinding 
wheels cause the initial openings of the V-shaped grooves through a 
substantial portion of the thickness of the sleeve while the knives, 
positioned in pairs, are designed to cut the straps by penetrating into 
the groove to sever through the relatively thin amount of rubber sleeve 
which remains. Thus, the goal of this prior art device is to first shape a 
groove in a relatively soft elastomeric material which is then severed 
into individual bands so as to result with belts which have been beveled 
to have a V-shaped configuration. 
In contrast, the present invention is directed to solving a completely 
different problem of reducing or eliminating peeling or scaling of a 
relatively hard coating from a cylinder whose end surfaces after cutting 
into tubular pieces must be essentially planar and as perpendicular to the 
longitudinal axis of the tube as possible. 
SUMMARY OF THE INVENTION 
The present invention is directed to an apparatus for cutting a cylinder 
supported on a mandrel having a longitudinal axis into tubular pieces 
which includes means for abrading positioned laterally with respect to the 
cylinder and located in a plane perpendicular to the longitudinal axis of 
the cylinder, the means for abrading being adapted to move transversely 
with respect to the longitudinal axis of the cylinder so as to make 
contact with the cylinder to form a groove having a bottom in the 
cylinder; means for cutting located in the plane perpendicular to the 
longitudinal axis of the cylinder and positioned laterally with respect to 
the cylinder, the means for cutting being adapted to move transversely 
with respect to the longitudinal axis of the cylinder to contact the 
bottom of the groove and to slice the cylinder into pieces, wherein the 
means for abrading includes a disc preferably provided with a beveled 
circumferential edge having a V-shaped such as a grindstone, and the means 
for cutting is a knife fixed in rotation. 
The apparatus in accordance with the present invention, as described above, 
is preferably provided with a means for reshaping the beveled edge of the 
grinding wheel positioned laterally with respect to the grinding wheel and 
adapted to move diagonally with respect to the plane perpendicular to the 
longitudinal axis of the cylinder so as to contact the beveled edge of the 
grinding wheel. 
The present invention is also directed to an apparatus, as described above, 
wherein a knife and a grindstone are positioned laterally on the same side 
of the cylinder, preferably with the knife being positioned below the 
grindstone, and preferably further including a jack journalled at one end 
of the framework and at another end to an arm with the arm being pivotally 
mounted on a support connected to the framework and having an end adapted 
to mount the knife, and a jack journalled at one end to the framework and 
at another end to an arm which is pivotally mounted on a support and 
having an end adapted to rotatably mount the grindstone. 
In particular, the present invention is directed to an apparatus for 
cutting a cylinder into tubular pieces, as described above, which also 
includes at least one carriage mounted for movement along a means for 
guiding located in a plane transverse to the longitudinal axis of the 
cylinder and connected to the framework; a support for the grindstone 
mounted on a carriage; and a support for a knife mounted on a carriage, 
preferably including means for imparting movement operably connected to 
the at least one carriage and wherein the framework includes abutments for 
stopping the movement and means for reversing movement of the at least one 
carriage in communication with the means for imparting movement, the means 
for reversing movement being positioned so that the carriage contacts an 
abutment and a means for reversing movement at essentially the same time. 
The present invention is also directed to an apparatus, as described above, 
which includes a first carriage to which a support for the grindstone is 
mounted and a second carriage to which the knife is mounted with the 
grindstone being positioned diametrically opposite the knife, and 
preferably wherein a means for adjusting the position of the support for 
the grindstone is moveably mounted to the first carriage. 
The present invention is also directed to a method for cutting a cylinder 
into pieces which involves positioning an elongate element having a 
cylindrical surface on a mandrel; contacting the elongate element with a 
means for abrading to effect a groove around its cylindrical surface; 
introducing a means for cutting into the grooves to begin slicing the 
elongate element at the bottom at the groove; and continuing the slicing 
of the elongate element until it is divided into pieces, wherein the 
surface of the cylinder has the thickness and the groove has a depth a 
fraction of less than about 1/5, and preferably about 1/10 of the 
thickness of the surface of the cylinder. 
The present invention is directed to a method as described above, which 
involves controlling the contact of the means for abrading with the 
elongate element so as to prevent the means for abrading from making 
contact with the mandrel. 
The present invention is also a method, as described above, wherein the 
means for abrading has the shape of a disc and further involves rotating 
the elongate element in a direction around axis of 7 the mandrel and 
rotating the disc in the same direction. 
The present invention is further directed to a method, as described above 
wherein resultant pieces have ends with surfaces which are essentially 
plane and perpendicular to the longitudinal axis of the pieces. 
The present invention is also directed to a method, as described above, 
which further involves providing a coating on the surface of the elongate 
element, which is preferably permitted to harden.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
According to one embodiment of the present invention, the mill and the 
knife are each mounted in position on a different carriage positioned on 
either side of a vertical plane passing through the longitudinal axis of 
the cylindrical tube to be cut. In this manner, the carriage may be moved 
in a plane which is essentially perpendicular to the axis of the tube 
between an initial position and a maximum position of work which may be 
adjustable depending on the diameter of the tube and the depth of the 
desired milling and/or cutting or the reduced diameter of the knife or 
polishing wheel resulting from the wear and tear of normal use. It is 
preferable to position the knife on its carriage diametrically opposite to 
the grinding wheel in their respective relationships to the tube. If this 
is the case, the grindstone or polishing wheel is positioned on a moveable 
carriage by means for support which is itself adjustably positioned on the 
carriage depending upon the previously mentioned conditions. Accordingly, 
the position of the grinding wheel on the support may be periodically 
adjusted to ensure that a relatively constant impression is made in the 
surface of the tube when the mill is brought into play. 
According to another embodiment of the present invention, the knife and 
polishing wheel may be pivotably mounted so as to be activated by a means 
for control so that the grindstone and knife act successively by each 
pivoting between two extreme positions with the maximum position of work 
being predetermined based upon the diameter of the tube and the desired 
depth of grinding taking into consideration the extent to which the 
diameter of the polishing wheel has been reduced as a result of normal 
wear. In this case, the knife and the grindstone are positioned, 
preferably with the former underneath the latter, on the same side with 
respect to a vertical plane through the longitudinal axis of the 
continuously formed cylinder. 
In accordance with the present invention, the main purpose of the 
grindstone is to prepare the surface of the tube, for example by scoring a 
groove, for subsequent cutting. The grindstone or polishing wheel itself 
is not intended to do the actual shaping or cutting the cylinder into 
pieces. Accordingly, the grindstone is preferably disk-shaped having a 
wedge-shaped circumferential edge when it is placed in rotation in the 
same direction as the tube although different shapes or profiles of the 
grooves are possible so long as sharp ridges are avoided. 
In this regard, the present invention also provides for a means for 
shaping, sharpening or otherwise rejuvenating the initial profile of the 
grindstone or polishing wheel. Although this is usually done when the 
grindstone is not in use, the present invention also provides for means 
whereby the grindstone can be subjected to such action while in operation. 
When the apparatus of the present invention is provided with means to 
adjust the position of the carriage which transports the grindstone in one 
embodiment, or by adjusting the means for pivoting the grinding wheel in 
the second embodiment, the apparatus may be provided with means for 
sharpening the peripheral edge of the grindstone and knives as they are 
returned to their extreme position away from the tube. The means for 
sharpening are brought into play by activating means which are positioned 
in a fixed manner laterally with respect to the tools when the tools are 
brought into their extreme position away from the tube. Related to this, 
if the circumferential edge of grindstone 5 is wedge-shaped, the sides of 
the wedge can be shaped to be slightly concave in such a manner that the 
resultant groove in the surface of the tube would be slightly convex 
having ridges which are slightly rounded. 
In the situation where the apparatus of the present invention is positioned 
at the end of a spiraler, it is necessary for the means for cutting to 
follow the progression of the tube as it is formed in a continuous manner. 
Accordingly, the grindstone and the knife can be adapted to move 
longitudinally along with the advancement of the tube, as well as to be 
returned to its initial position. In addition, the apparatus of the 
present invention has utility for cutting single, rather than continuously 
formed, cylindrical tubes. 
Turning now to the drawings, FIG. 1 shows a cylindrical tube 1 formed from 
cellulosic materials, such as cardboard or paper strips, positioned on a 
mandrel 20 or other means for supporting the tube. A knife 2 as a means 
for cutting is mounted on carriage 3 which is operably associated with 
framework 4 positioned at one side of the cylindrical tube. A disc-shaped 
grindstone or polishing wheel 5 as a means for milling is also mounted on 
a movable carriage 6 which is operably associated with framework 7. As 
shown in FIG. 1, tube 1 is rotated in the direction of arrow F1 shown to 
be counterclockwise, with means for grinding 5 being rotated in the same 
direction as shown by arrow F2. In the illustrated embodiment, the disk is 
rotated by means of a belt mounted around a shaft connected to a pulley 
motor 8 although other conventional drive mechanisms could be suitably 
used for purposes of rotating the disk. Carriage 3 for transporting knife 
2 and carriage 6 for transporting the grindstone or polishing wheel 5 are 
positioned on either side of cylindrical tube 1 in such a manner that the 
knife and the grindstone are diametrically opposed to each other with 
respect to tube 1. In operation, the carriages 3 and 6 are activated to 
transport, respectively, knife 2 and grindstone 5 transversely with 
respect to the longitudinal axis of the tube towards and away from the 
tube by means of jacks 9 and 10, respectively, which may be mechanically, 
pneumatically, or hydraulically operated. Carriages 3 and 6 are mounted on 
rods 41 and 43, respectively, as means for guiding the carriage so as to 
ensure their precise course of action. Attached to frameworks 4 and 7 are 
abutments 11, 12, 13, and 14 which define the length of transverse 
movement of carriages 3 and 6 within their respective frameworks. Although 
abutments 13 and 14 are shown for purposes of example as being fixedly 
mounted to the framework, the abutments are preferably adjustably mounted 
to their framework in the manner shown for abutments 11 and 12. 
Accordingly, the path of the carriages may be shortened or lengthened to 
accommodate different sized tubes, knives and grindstone by adjusting the 
position of the abutments. In this regard, abutments 11 and 12 are shown, 
for example, as being threadedly engaged through tapped openings in 
framework 4. 
The grindstone or polishing wheel 5 has a circumferential edge which is 
shown more clearly in FIG. 3 as being wedge-shaped. The grindstone 5 is 
mounted for rotation on a support which in turn is operably associated 
with carriage 6 by means of a micrometer screw-type adjustment rod 18. The 
support 17 is moved transversely towards and away from tube 1 by turning a 
wheel equipped with a handle or crank 19 which is attached to an end of 
adjustment rod 18, although any conventional power source can be used for 
this purpose. 
In FIG. 1, carriages 3 and 6 are shown in their extreme distant positions 
with respect to tube 1. In order to effect the cutting of the tube, jack 
10 is activated to cause carriage 6 on which grindstone 5 is supported 
towards tube 1. Upon contact of the disk with the tube, the grindstone 
begins abrading the surface and penetrates the tube to a predetermined 
depth, for example less than 20% and preferably about 10% of the thickness 
of the tube. The depth to which the disk penetrates the tube is controlled 
by the distance carriage 6 moves along guide rod 43 which is ultimately 
determined by the length or position of abutment 13 and microcontacts 16 
which are mounted in framework 7 in such a way that advancement of the 
grindstone 5 is not permitted to proceed to such an extent that the 
grindstone would abrade completely through the tube and come into contact 
with mandrel 20. Framework 4 is similarly provided with microcontacts 15 
and 15'. Whereas abutments 11, 12, 13, and 14 act as physical stops to the 
movement of the carriages, microcontacts 15, 15', 16, and 16' are 
electronically connected to a power source for jacks 9 and 10 to activate 
their movement. For example, when carriage 6 stops against abutment 13, 
carriage 6 also makes contact with microcontact 16 which sends a signal to 
the drive mechanism for jack 10 to cause it to reverse its direction and 
retract carriage 6 to a readiment position away from tube 1. The abutments 
and microcontacts mounted to framework 4 operate in a similar fashion with 
respect to the movement of knife 2 supported on carriage 3. 
The knife is brought into play once disk 5 has scored a groove around tube 
1 by penetrating first into the groove left by the disk and then into the 
tube itself until carriage 3 comes into contact with abutment 12 and 
microcontact 15 to stop its forward movement. The activation of 
microcontact 15 then causes a reversal of the movement of jack 9 so as to 
retract carriage 3 away from tube 1 until the carriage comes into contact 
with abutment 11 and microcontact 15' whereat the elements are once again 
in their initial readiment position, as shown in FIG. 1, in anticipation 
of another cutting cycle. 
FIGS. 2 and 3 show means for sharpening or rectification of the grindstone 
or polishing wheel which are preferably diamonds 21 and 22 reciprocally 
moveable towards and away from grindstone 5 by the action of jacks 23 and 
24. The jacks 23 and 24 are mounted on supports 25 positioned on either 
side of grindstone 5 and may be attached to framework 7. This particular 
arrangement permits grindstone 5 to be sharpened or reshaped periodically 
when carriage 6 is retracted to its extreme distant position away from 
tube 1. 
The arrangement of support 17, to which grindstone 5 is mounted, on 
adjustment rod 18 allows for the distance of the support relative to the 
exterior surface of the tube to be adjusted so as to accommodate the 
change in diameter of the grindstone as a result of being sharpened or 
reshaped. In this manner, the circumferential edge of the grindstone still 
occupies the same relative position with respect to the work plane, i.e., 
the exterior surface of the tube to be cut, despite the decrease in the 
diameter of the grindstone. Accordingly, abutments 13 and 14 do not have 
to adjusted as a result of this operation, and may be fixed as shown, 
rather than being adjustably mounted, in position on framework 7. Although 
the adjustments to the position of support 17 and the shaping of the 
circumferential edge of grindstone 5 may be carried out manually, these 
elements can be connected to electronic equipment which can be programmed 
to perform these functions automatically. 
Although the relative position of the circumferential edge of the 
grindstone with respect to the exterior surface of the tube is maintained 
essentially constant by the manipulation of adjustment rod 18 to 
accommodate for a loss in diameter of the disk, this result could also be 
achieved by adjusting abutments 13 and 14, if necessary. 
FIG. 4 shows another preferred embodiment according to the present 
invention. As in the other embodiments, tube 1 is supported by mandrel 20. 
As shown, two rollers 26 and 27 are provided to guide and rotate tube 1 in 
its longitudinal movement from the forming station towards the cutting 
station. In this embodiment, however, grindstone 5' and knife 2' are 
mounted on arms 28 and 29, respectively, which are pivotally connected to 
stanchions 30 and 31 mounted to framework 32. The arms 28 and 29 are 
connected to an end of jacks 33 and 34, respectively, the opposite ends of 
which are pivotally connected to mountings 45 and 47 which are attached to 
framework 32. 
Referring again to FIG. 4, knife 2' in preference fixed in rotation is 
positioned under grindstone 5' on the same side with respect to a vertical 
plane passing through the longitudinal axis of tube 1 although other 
suitable arrangements could also be used without departing from the spirit 
and scope of the present invention. It is also possible to provide this 
particular arrangement of the knife with respect to the grindstone so as 
to have a means for sharpening or shaping the circumferential edge of the 
grindstone in a manner similar to that which has been previously described 
with respect to the first embodiment. One could also use a grindstone or 
polishing wheel impregnated with diamond powder for either of the 
embodiments discussed herein. 
In operation, jacks 33 and 34 are controlled so that grindstone 5' is 
activated first by jack 33 which then retracts while jack 34 activates 
knife 2' before retracting itself in turn to return to the initial 
position wherein grindstone 5' and knife 2' are spaced away from tube 1. 
Although the extreme initial and final positions of arms 28 and 29 are 
predetermined, there are several means for controlling the positioning of 
these elements to ensure that the grindstone don's make contact with 
mandrel 20 during grinding or polishing similar to those previously 
described herein. In contract the knife 2' (or 2 FIG. 1) can take contact 
with mandrel 20 this latter being a special mandrel (for continuously 
formed tube) or being provided with a special port (for individual units 
of tube), disposed in front of the asaid knife and forming a counterknife 
which is into rotation with the said tube. Again, the diameter of the 
tube, the depth of the desired scoring, and the diameter of the particular 
element, taking into consideration its wear and tear, are factors which 
enter into making the necessary adjustments to ensure the precise 
operation of the apparatus. 
In applications where it is desired to move knife 2, 2' and disk 5 and 5', 
longitudinally with the movement of tube 1, frameworks 4, 7, and 32 with 
which these elements are associated, may in turn be mounted on a means for 
transporting 32a the respective assemblies in a longitudinal direction 
parallel to the longitudinal axis of tube 1. Accordingly, framework 4, and 
7 and 32 may be mounted to the carriage which is adapted to move 
reciprocally back and forth for a predetermined distance along the path of 
tube 1. 
The depth of the score or groove to be effected by grindstone 5 will depend 
primarily upon the hardness of the surface coating as well as the 
thickness of the coating. In general, however, the thickness of the 
coating is minimal with respect to the thickness of the tube itself. 
Consequently, the cutting action of the knife is significantly greater 
than the action of the grindstone which penetrates into the surface of the 
tube to a relatively insignificant degree, i.e., a maximum of about 20% of 
its thickness. 
From the foregoing description, one skilled in the art can easily ascertain 
the essential characteristics of this invention and, without departing 
from the spirit and scope thereof, can make various changes and 
modifications of the invention to adapt it to various usages and 
conditions.