Apparatus for producing reinforced tubing

A completely automatic process and apparatus are described for producing multi-layer rubber or plastics tubes reinforced with fabric tapes or metal wires. The apparatus is new both overall and in its individual component units. Specifically, spiral-forming units of new design are described, which operate in series to each apply a different tape material as a spiral on to the metal core which is fed with rectilinear motion, to form a continuous layer thereon. Unwrapping units are also described for automatically removing and rewinding the outer forming tape for the finished tube.

This invention relates to a completely automatic process for producing 
rubber or plastic tubes reinforced with fabric and/or metal wire or tape. 
The invention also relates to a completely automatic apparatus for carrying 
out the new process for producing reinforced rubber or plastic tubes. 
The apparatus is new both overall and in each of its component parts. 
There is a practically unlimited range of rubber or plastic tubes 
reinforced with one or more identical or different fabrics, and possibly 
with one or more windings of identical or different metal wires or tapes. 
By varying the type of rubber or plastic used, by varying the type and 
number of reinforcement fabrics, and possibly using metal reinforcements 
of different types, it is possible to produce tubes suitable for any 
industrial or agricultural use. 
For simplicity, the articles which can be produced by the new process and 
apparatus according to the present invention will be called "reinforced 
rubber tubes," it being understood that this comprises the entire range of 
possible reinforced tubes as heretofore defined, and more precisely 
described hereinafter. 
In general, a reinforced rubber tube means an article of prevalently 
annular cross-section, comprising essentially three fundamental layers: 
A. an innermost layer or substrate of natural or synthetic rubber or 
synthetic plastic which is impermeable and chemically inert to the fluid 
conveyed; 
B. one or more intermediate layers of fabric or tape comprising parallel 
filaments (filaments or fabric of nylon, polyester, cotton, artificial 
fiber, steel, copper and the like), the purpose of which is to enable the 
tube to resist the pressure of the conveyed fluid and to retain its shape; 
C. an outer layer or covering formed from continuous or woven tape of 
artificial or synthetic material, the purpose of which is to enable the 
tube to resist the external agents which vary considerably according to 
the use for which the tube is intended, and the environment in which it is 
located, such as atmospheric agents, chemically reactive fluids, soil, 
abrasive forces, heat, low temperatures etc. 
Such reinforced rubber tubes have been produced on a rigid or flexible 
mandrel, by processes which can be briefly summarized as follows: 
1. the inner substrate is prepared by spirally winding a crude rubber or 
synthetic tape manually or semi-automatically about a rotating cylindrical 
mandrel. The intermediate and outer covering layers are prepared in a like 
manner. 
Using the same method, an outer wrapping, generally of thermally and 
mechanically resistant nylon fabric, is then applied to the rotating 
manual in order to externally shape the tube, this wrapping being removed 
when the tube is finished (unwrapping). 
If the inner layer and possibly one or more of the intermediate layers are 
of crude rubber, the tube is vulcanized after forming but before 
unwrapping. 
This method is very costly because it requires a great deal of labor, but 
represents the method which is most widely used as it allows tubes to be 
produced with the most diverse characteristics. 
2. The inner substrate is prepared by extruding crude rubber or synthetic 
thermoplastic material on a mandrel. 
The intermediate layers and the covering layer are prepared, as in the 
first method, by spirally winding fabric tapes from various fibers or 
metal wires about the rotating mandrel covered by the substrate, either 
manually or semi-automatically. 
If the extruded substrate is of crude rubber, the tube is again vulcanised 
before unwrapping. 
According to a modification of this method, in addition to the substrate, 
further layers can be applied by extrusion or drawing, rather than by 
spirally winding tapes. 
According to a further modification, wrapping with mechanically and 
thermally resistant fabric is replaced by the application of a lead sheath 
which is removed after vulcanisation. 
This method, which is less prevalent than the preceding method, is also 
very costly because of the high labor requirement. 
3. The substrate is applied by extrusion or winding as in the preceding 
methods. 
In contrast, the intermediate and covering layers are applied in a 
horizontal plane by a machine which winds continuous fabric layers in the 
manner of a cigarette. 
This is the least versatile method. This is of the most limited application 
because the equipment necessary for carrying it out is very costly and 
requires a great deal of space. 
A completely automatic continuous method for the formation of reinforced 
rubber tubes has now been discovered, and forms the subject matter of the 
present invention. It is characterised in that both the rubber layers and 
fabric layers, in the form of tapes, are applied with rotary motion on to 
a rigid metal core which fed in a rectilinear direction, so that they form 
successive spirally wound, superposed layers on the core. 
The continuous spiral form assumed by the layers is the resultant of the 
rectilinear translatory motion of the core and the rotary motion about the 
same imparted to the tape. 
The present invention also relates to a completely automatic apparatus for 
producing tubes by the successive application, as a spiral forming a 
continuous layer, of rubber tapes, fabric tapes of various kinds, and 
outer wrapping tapes about a rigid metal core fed with rectilinear motion, 
according to the process of the present described above. 
The new process consists essentially of feeding a metal core with 
rectilinear motion through various series-disposed units rotating 
concentrically to the core. The units wind a spiral of tape consisting of 
rubber, synthetic material or fabric of natural or synthetic fibers, and 
finally the forming wrapping above the core. 
After an optional vulcanization stage, the new process further comprises 
the automatic removal of the outer forming wrapping for the tube by 
rectilinearly feeding the core supporting the formed tube through a unit 
which rotates in the opposite direction to the preceding units. 
The machine according to the present invention essentially comprises: 
1. a unit for feeding the metal support core for the tube with rectilinear 
motion 
2. several identical units disposed in series concentric to the fed metal 
core, each arranged to apply a different kind of tape to the metal core in 
order to form on it a continuous spiral structure. 
The first unit applies the spiral layer directly to the core, whereas the 
subsequent units apply the spiral layers superposed on the preceding 
layers to form the stratified structure characteristic of reinforced 
rubber tubes. 
The last series-disposed unit applies the outer wrapping layer in the same 
manner. 
These spiral-forming units are constituted essentially by a spool 
concentric to the metal core and carrying the reel of tape to be applied; 
a disc adjacent to the spool and independently concentric to the metal 
core, and on which two suitably inclined arms are fixed in suitable 
positions for taking-up and tensioning the rubber or fabric tape; a mobile 
tensioning arm mounted on a cam independent of the disc and having a 
limited stroke which enables it to absorb and balance any abnormal 
tensions in the tape, especially during the starting and stopping of the 
system; a metal disc of diameter approximately equal to the spool and 
lying opposite this spool, and comprising a tightening arm of suitable 
shape which rests on the tape to prevent it from deforming and forming 
creases. 
The spool carrying the roll of tape and the disc comprising the tightening 
arm are driven with rotary motion in opposite directions by two 
independent motors. 
Their rotary movement combined with the rectilinear motion of the core 
leads to the formation of the continuous rubber or fabric spiral on said 
core. 
3. an optional rubber tube vulcanization apparatus, which is of the type 
generally known in the art and does not itself form part of the present 
invention. 
4. a unit for driving the formed tube with rectilinear motion. 
5. an unwrapping unit constituted essentially by a disc concentric with the 
advancing tube, having pivoted on its surface, by way of a friction disc, 
a spool for winding the wrapping tape removed from the finished tube. 
The disc is rotated by a motor in such a direction as to unwind the 
wrapping from the tube surface. Simultaneously, the spool, which is fixed 
on a pinion engaging with a fixed gear wheel concentric to the finished 
advancing tube and adjacent to the rotating disc, is compelled to rotate 
about itself, thus rewinding the wrapping tape as it is removed from the 
tube. 
6. a unit for moving the finished tube rectilinearly, this unit being 
identical to the preceding units. 
7. means for detaching the tube from the core, and for coiling the finished 
tube, this apparatus also being known in the art and not forming part of 
the present invention.

Identical parts are identified by identical reference numerals throughout 
the drawings. 
In FIGS. 1, 2, 3 and 4, the reference numeral 6 indicates the metal core 
feed unit, 14 the support columns on which the plant rests, and 4 the 
rotating disc which winds the rubber or fabric tape about the core. This 
disc can be of any suitable material, for example light alloy or rigid 
synthetic resin, for example of the polyacrylic or polystyrene type, and 
is preferably of transparent synthetic resin. 2 and 3 indicate rigid arms 
of any suitable material, preferably of light alloy, fixed on the disc 4 
at such an inclination as to transmit the required positioning and tension 
to the tape. 1 indicates the tensioning arm, independent of the disc 4 and 
fixed on to a cam which enables it to make a limited stroke when pulled by 
an abnormal tension in the tape 5 (in particular during the starting and 
stopping of the plant), the amplitude of the movement which the cam allows 
the arm 1 to make being particularly visible in the detailed view of FIG. 
2. 12 indicates the roll of rubber or fabric tape mounted on the spool 
concentric to the metal core. 7 indicates the tightening arm which rests 
on the rubber or fabric tape and is fixed in a suitable position on a 
fixed metal disc which opposes the rotating disc 4. 8 is the drive motor 
for the spool carrying the reel of tape 12; and 13 indicates the drive 
motor for the rotating disc 4. 
With reference to FIG. 4, it can be seen that by means of the brackets 16, 
the support columns 14 support a fixed cylinder 10 in which the metal core 
15 slides. The cylinder 9, which transmits the motion of the motor 13 to 
the disc 4, and the cylinder 11, which transmits the motion of the motor 8 
to the roll carrying spool 12', are disposed concentrically to the 
cylinder 10 and slidable on it. 
It can be seen from FIG. 4 that the movement of the roll 12 and disc 4 are 
completely independent. 
In reality, these two elements are rotated in opposite directions, the 
spool for unwinding the tape and the disc for picking up the tape and 
winding it about the core, with a speed ratio such as to ensure constant 
tension in the tape as the roll diameter decreases. 
It should be particularly noted that as the roll 12 is directly supported 
by the load-bearing structure of the plant by way of the cylinder 11, it 
can have a diameter of up to 1 meter, and can therefore ensure a 
considerable time between roll changes, increasing the self-sufficiency of 
the plant. 
FIG. 4 also shows the brake disc 30 for the roll 12 and the brake disc 31 
for the disc 4. 
In FIGS. 5 and 6, the reference numerals 6' and 6" respectively indicate 
the driving unit for the possibly vulcanized formed tube 17 and the 
driving unit for the unwrapped finished tube 18. 24 indicates the support 
column for the unwrapping unit on which the fixed support cylinder 26 
rests, 19 indicates the rotating disc concentric to the feed axis of the 
tube, this disc being constructed of a material which is light or is 
lightened by means of apertures or the like, and which during its movement 
detaches the wrapping applied to the outer surface of the possibly 
vulcanized formed tube. The disc 19 is driven by the motor 23, by way of 
the cylinder 27 which rotates on the fixed cylinder 26. The collection 
spool 20 is fixed on the disc 19, with the friction disc 21 interposed. 
The spool 20, besides being dragged by the motion of the disc 19, also 
engages with the ring gear 22 by way of pinion 25, which causes it to 
rotate about its own axis. 
By suitably adjusting the unwrapping speed transmitted by the motor to the 
disc 19 and the pitch of the ring gear 22, a complete rewinding of the 
entire tape 29 detached from the finished tube 18 is obtained. 
FIG. 6 also shows the brake disc 28 for the rotating disc 19. When removed 
and rewound automatically by means of the unwrapping unit of FIGS. 5 and 
6, the wrapping tape (generally nylon tape) can be reused several times. 
The process and apparatus illustrated on the accompanying drawings 
represent only a preferred embodiment, and various modifications can be 
made to the details thereof without leaving the scope of the inventive 
idea. 
It is possible, for example, to mount the collection spool 20 of the 
unwrapping unit concentric to the advancing tube, in a manner analogous to 
the spools of the spiral forming units. 
It should also be noted that the new apparatus comprises control and 
synchronization means which automatically vary the speeds of the spiral 
forming and unwinding units in accordance with the feed speed of the metal 
core. These control and synchronization means in all cases enable all the 
stages of the process to be carried out continuously with minimum use of 
labor, and eliminate the down times normally existing between one stage 
and another. 
The new process according to the present invention consequently has the 
following advantages over processes of the known art: it requires minimum 
use of labor; it enables any type of tube to be produced without 
limitation on length or quality, with diameters for example variable from 
15 to 60 mm; it considerably reduces operating time and thus 
correspondingly increases hourly production; it allows production with 
absolutely constant characteristics; and offers the possibility of 
continuous operation with a self-sufficiency which is far greater than 
that attained up to the present time.