Tube holding or guiding apparatus

A tube is held or guided parallel to its length by providing a channel-like structure aligned with the tube and having sides which are spaced apart by a distance less than the diameter of the tube. Circumferentially spaced longitudinal portions of the outer surface of the tube bear respectively on the two sides of the channel. The channel is open to the outer surface of the tube between those longitudinal portions, and the bottom of the tube is spaced from the outer surface of the tube between those longitudinal portions. The tube is held against the channel-like structure by directing a stream of gas (e.g., air) along the channel.

BACKGROUND OF THE INVENTION 
This invention relates to apparatus for handling tubular articles such as 
cigarettes, tubular cigarette components, spiral wound paper and/or foil 
tubes, etc., and more particularly to apparatus for holding or guiding 
such articles parallel to their length. 
There are many instances in tube making or handling where a tube must be 
held or guided parallel to its length. For example, in the typical 
cigarette making machine, the tobacco rod is initially formed as a 
continuous tobacco-filled paper tube which moves continuously parallel to 
its length as it is made. The end portion of this tube is periodically cut 
off to form cut lengths of tube (e.g., by a conventional Molins Mark VIII 
cutter head available from Molins of London, England). Each successive cut 
length is then accelerated parallel to its length (e.g., by the spiral 
spacer wheel in a conventional Molins Mark VIII cutter head) in order to 
place the cut length in the next successive flute on a fluted catcher drum 
which is rotating about an axis parallel to the longitudinal axis of the 
initial continuous rod. From that point on, the cut lengths tend to move 
transverse to their longitudinal axes (e.g., for such purposes as the 
addition of filters). 
Between the point at which the cutter head cuts the tube and the point at 
which the spiral spacer wheel takes over control of the cut length in 
order to accelerate it into a catcher drum flute, the cut length of tube 
must be kept under control so that it remains in line--pushed along by the 
tube behind--but so that it can be freely accelerated once it reaches the 
spiral spacer wheel. The spiral spacer wheel also typically deflects the 
path of the tube slightly transverse to its longitudinal axis in order to 
facilitate insertion of the tube into the next catcher drum flute. The 
tube controlling elements must therefore not be so rigid or inflexible as 
to prevent this necessary tube deflection. 
Heretofore the typical means for controlling the cut lengths of tube from 
the point at which they are cut to the point at which they come under 
control of the spiral spacer wheel have been spring fingers which 
resiliently press the tube against tube-supporting and guiding surfaces. 
Such spring fingers tend to be delicate, easily damaged when the machine 
jams or when a jam is being cleared, and difficult to adjust for optimum 
performance. 
Although the foregoing shortcomings of the prior art have been described in 
the context of handling tobacco-filled rods, the same problems may be 
encountered in handling tubes of other kinds. For example, in making 
spiral wound tubes of paper and/or foil as shown, for example, in Meyer 
U.S. Pat. No. 4,473,368, it is sometimes necessary to guide the cut off 
lengths of tube in a manner similar to that described above, so that the 
above-mentioned shortcomings of the prior art are encountered again. 
In view of the foregoing, it is an object of this invention to provide 
improved and simplified tube holding or guiding apparatus. 
It is a more particular object of this invention to provide tube holding or 
guiding apparatus which is extremely reliable, robust, and easy to adjust. 
SUMMARY OF THE INVENTION 
These and other objects of the invention are accomplished in accordance 
with the principles of the invention by providing apparatus for holding a 
tube on a predetermined path parallel to the longitudinal axis of the tube 
comprising: a first surface parallel to said path for contacting a first 
longitudinal portion of the outer surface of said tube; a second surface 
parallel to said path for contacting a second longitudinal portion of the 
outer surface of said tube which is circumferentially spaced from said 
first portion, the circumferential spacing being less than 180.degree.; a 
longitudinal channel between said first and second surfaces, said channel 
extending parallel to said path and opening toward the outer surface of 
said tube between said first and second longitudinal portions, the bottom 
of said channel being spaced from the outer surface of said tube; and 
means for directing a stream of gas (e.g., air) longitudinally along said 
channel to hold said first and second portions against said first and 
second surfaces respectively. 
Further features of the invention, its nature and various advantages will 
be more apparent from the accompanying drawings and the following detailed 
description of the preferred embodiments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In the illustrative embodiment shown in FIGS. 1-3 tube 10 is formed and 
advanced continuously by conventional tube former 20 (e.g., a conventional 
garniture or spiral tube winder). Conventional cutter 22 operates 
periodically to cut tube 10 into predetermined lengths. After passing 
cutter 22, tube 10 passes between guides 32 and 34 on table 30. Guide 32 
is relatively short parallel to the longitudinal axis of tube 10, but 
guide 34 extends much farther in that direction toward conventional spiral 
spacer 50. As each cut length of tube 10 passes from cutter 22 to spiral 
spacer 50 it is supported by table 30. In addition, a longitudinal portion 
of the circumference of each cut length of tube 10 spaced from the surface 
of table 30 bears against surface 36 of guide 34. Between surface 36 and 
the surface of table 30 guide 34 is recessed away from the surface of tube 
10 to define (with table 30) a channel 38 which (1) extends parallel to 
the longitudinal axis of tube 10, and (2) opens toward the circumferential 
surface of tube 10. It should be noted that surface 36 is spaced less than 
180.degree. around tube 10 from the portion of the surface of table 30 
which also contacts the tube. In particular, in the depicted embodiment, 
surface 36 is spaced approximately 90.degree. around tube 10 from the 
portion of the surface of table 30 which also contacts the tube. 
Disposed in the upstream portion of channel 38 is a gas discharge nozzle 40 
which is directed in the downstream direction (i.e., substantially 
parallel to the longitudinal axis of tube 10 and in the direction of 
motion of tube 10). Nozzle 40 directs a flow of gas (e.g., air) from 
pressurized gas source 42 along channel 38 parallel to the direction of 
motion of tube 10. This gas flow, by operation of the Bernoulli effect, 
has the tendency to pull tube 10 in toward channel 38, thereby holding the 
tube against surface 36 and the surface of table 30. Tube 10 is thereby 
guided parallel to surface until spiral spacer 50 takes over control of 
the tube. In particular, as is conventional, spiral spacer 50 accelerates 
each cut length of tube 10 and deflects it somewhat transverse to its 
initial direction of motion in order to put each cut length into the next 
succeeding flute in a conventional fluted transport drum (not shown). The 
force exerted on tube 10 by the gas stream from nozzle 40 is great enough 
to hold each cut length of tube 10 against surface 36 and table 30 as each 
cut length is pushed along by the succeeding tube, but that force is not 
so great as to interfere with the operation of spiral spacer 50. In other 
words, as soon as each cut length of tube 10 reaches spiral spacer 50, the 
spiral spacer can easily longitudinally accelerate and transversely 
deflect that cut length in the desired manner, thereby taking over control 
of the continued motion of the cut length. 
Because each cut length of tube 10 is held to the guiding surfaces by 
differential gas pressure (i.e., the above-mentioned Bernoulli effect), 
there are no spring fingers to impede clearance of any possible jam or to 
become damaged, worn, or out of adjustment. Moreover, unlike spring 
fingers, which it may be difficult to optimally adjust, the apparatus of 
this invention is easily and precisely adjustable by control of the gas 
flow through nozzle 40. 
It will be understood that the foregoing is merely illustrative of the 
principles of this invention, and that various modifications can be made 
by those skilled in the art without departing from the scope and spirit of 
the invention. For example, tube 10 may be any of a wide variety of tubes 
formed of various materials by various tube former devices.