Marking apparatus

A marking apparatus that is useful for marking a line upon a ridge protruding from a surface of a continuously passing elongated article is disclosed. A stylus member of the marking apparatus has a notch in its foot, through which the ridge on the article passes. A tracking arm member is pivotally attached to a bar member, and supports the stylus member, so that the stylus member can follow the track of the ridge even if the article wanders from side to side as it passes the marking apparatus. Marking fluid, stored in a reservoir, passes through a hollow tube and a bore through the stylus member which communicates with the notch in the foot of the stylus member.

BACKGROUND OF THE INVENTION 
The present invention relates to a marking apparatus for marking a line 
upon an elongated article that is continuously moving past the marking 
apparatus, and more particularly to a marking apparatus for making a line 
that is guided by a ridge protruding from a surface of the article that is 
to be marked. 
U.S. Pat. No. 4,106,965 teaches an apparatus for making a visible reference 
line on a continuously extruded body of rubbery material, such as a tread 
for a pneumatic tire. The apparatus taught in that patent has a plurality 
of rotating wheels that rest upon the extrudate and a transfer roller for 
transferring the marking fluid from a reservoir to the article that is to 
be marked. The weight of the apparatus, as well as that of the marking 
fluid in the reservoir, is passed through the rotating wheels to the 
extrudate. An extrudate of a soft material, such as the elastomeric 
compounds used in the treads of some race car tires, may be permanently 
deformed by the force transferred through the rotating wheels. An 
apparatus according to the present invention may be made much more 
lightweight than this prior art apparatus, and because it has fewer moving 
parts is less susceptible to mechanical failures. Other advantages of a 
marker according to the present invention over prior art markers will be 
pointed out later in this specification. 
Simply put, a marking apparatus according to the present invention may be 
used to mark a line upon a ridge protruding from a surface of an elongated 
object that is continuously moving past the marking apparatus in a 
direction that is longitudinal with respect to the elongated article. 
After the marking has taken place the elongated article may be cut into 
lengths or rolled around a core. Examples of elongated articles that may 
be marked with lines by the marking apparatus are treads for tires, 
tubing, hoses and belts. The lines made by the marking apparatus may be 
used as a location reference or for idendification purposes. 
There is provided in accordance with an aspect of the present invention a 
marking apparatus comprising: a bar member supported by a means for 
support; a tracking arm member having first and second ends, the first end 
of said tracking arm member being pivotally attached to said bar member, 
said tracking arm member extending generally in a direction transverse to 
said bar member; a stylus member attached to said tracking arm member near 
the second end of the tracking arm member, said stylus member having a 
foot with a notch therein, said notch being oriented parallel with the 
longitudinal axis of said tracking arm member, said stylus member having a 
bore therethrough with first and second ends, the first end of said bore 
communicating with the notch in said foot, said bore having a 
cross-sectional width at its first end that is less than the 
cross-sectional width of said notch; a reservoir for marking fluid, said 
reservoir having an outlet; and, a hollow tube having a pair of ends, one 
end of said hollow tube communicating with the outlet of said reservoir 
and the other end of said hollow tube communicating with the second end of 
the bore through the stylus member.

DETAILED DESCRIPTION OF THE INVENTION 
Referring to FIG. 1, there is shown a schematic representation of a marking 
apparatus according to the invention in its operative position. An 
extruder 10 of the type well known in the extrusion art forms an elongated 
article 11 by forcing an elastomeric material, such as a rubber compound, 
through a forming die. An endless converyor belt 12 continuously moves the 
elongated article along a path that is longitudinal with respect to the 
elongated article, as indicated by an arrow in FIG. 1. A marking apparatus 
13 is located downstream from the extruder and makes a continuous line 
upon the elongated article, as the elongated article is continuously moved 
past the marking device. It is understood that the elongated article to be 
marked may be cut into lengths or wound upon a core in a later stage of 
the production process. It is further understood if the elongated article 
is manufactured by calendering, or even is simply unwound from a 
pre-manufactured roll, the marking apparatus of the present invention may 
still be advantageously used to mark a line upon the article. 
FIGS. 2, 3 and 4 are cross-sectional views of elongated articles that may 
have lines made on them by a marking apparatus according to the invention. 
A typical tread strip 14 intended to be assembled with a tire is shown in 
FIG. 2. A ridge 15 protrudes from a surface of the tread at its 
centerline. The ridge 15 is formed by a notch in the forming die located 
in the head of an extruder. The ridge must be large enough so that its 
peak surface 16 can have a marking fluid applied thereon, but yet small 
enough that when the assembled tire is vulcanized the ridge can be merged 
with the remaining body of the tread without affecting the desired contour 
of the vulcanized tire. As will be more fully described later, a ridge on 
the surface of the extruded article will serve as a guide for the stylus 
member of the marking apparatus. While the articles shown in FIGS. 2, 3 
and 4 have only a single ridge located at their respective centerlines, it 
is understood that a marking apparatus according to the invention can be 
guided by a ridge located other than at the articles centerline, or may 
use more than one stylus member to mark a line on the peak surface of more 
than one ridge on the article. A person working in the tire making art may 
desire a visibly distinguishable line to be marked at the center of a 
tread to act as a reference line when placing the tread on a tire carcass, 
or for determining if the tire has been properly aligned in a curing mold. 
It is believed that the ridge protruding from the surface of an article to 
be marked may be of any desired dimensions, but preferably in the range of 
from 1.3 mm (0.05 inches) in height and width to about 1.8 mm (0.07 
inches) in height and width. While the ridges may be "V" shaped or "U" 
shaped, it is preferable that they be rectangular. 
FIG. 3 illustrates a newer type of tread strip 16, as is taught in U.S. 
Pat. No. 4,308,083. This new type of tread strip 16 has a plurality of 
depressed areas 17 that will align with the groove areas of the tread of 
the vulcanized tire. A ridge 18 protrudes from the tread strip at its 
centerline. A prior art marking apparatus of the type taught in U.S. Pat. 
No. 4,106,965 requires a broad surface to ride against, such as the tread 
strip 14 of FIG. 2 has. The stylus member of a marking apparatus according 
to the present invention is much narrower than the prior art marker 
though, and can be used to mark on ridges in depressions where the prior 
art markers could not effectively be used. 
FIG. 4 is a cross-section of a hollow tubular article 19, such as an inner 
tube or a hose. Such articles are commonly extruded and may have a notch 
20, of the type already described, protruding from an outside surface to 
be marked upon by the marking apparatus of the present invention. 
The articles shown in FIGS. 2, 3 and 4 are merely examples of articles that 
may have lines marked thereon by a marking apparatus according to the 
invention, and virtually any extruded article, of sufficient size, may be 
marked with the marking apparatus. 
Referring next to FIG. 5, there is shown a perspective view of a marking 
apparatus 21 in accordance with the preferred embodiment of the invention, 
in its operative position for marking a line upon a tread strip 22 of the 
type illustrated in FIG. 2. The tread strip is an elongated article that 
is continuously moving past the marking apparatus in a direction that is 
longitudinal with respect to the elongated article. In this instance a 
conveyor belt 23 carries the elongated article. If desired, one or more 
shrinkage rolls 24 may be employed in the conveyor system. The elongated 
article has a surface with a ridge 25 protruding therefrom, and extending 
in a longitudinal direction with respect to the elongated article. 
The marking apparatus has a bar member 26 supported by a means for support 
27. Preferably the bar member 26 is oriented horizontally, but a vertical 
bar member could be employed without deviating from the scope of the 
invention. The bar member is preferably oriented in a direction transverse 
to the direction of motion of the elongated article, and is spaced apart 
from the surface of the elongated article. 
A tracking arm member 28 has first and second ends, the first end of the 
tracking arm member being pivotally attached to the bar member 26. While 
any number of means for making a pivotal connection between the tracking 
bar member and the bar member may be employed, it is recommended that the 
tracking arm member be capable of pivoting in both the horizontal and 
vertical directions so that it can track the ridge protruding from the 
article if the article wanders from side to side of the conveyor belt or 
should vary in vertical height. Of course, the pivotal attachment allows 
the marking apparatus to be easily used for marking elongated articles of 
different thicknesses. The tracking arm member extends in a direction that 
is generally transverse to the bar member. Put another way, the tracking 
arm member is oriented generally in the direction of motion of the 
elongated article, and is slanted towards the surface of the elongated 
article, but is not in direct contact with the elongated article. The 
tracking arm member is slideable along the length of the bar member. 
A stylus member 30 is attached to the tracking arm member 28 near the 
second end of the tracking arm member. Preferably the stylus member is 
secured in place with respect to the tracking arm member by securing means 
such as a set screw 31, or a clip, so that the stylus member can be easily 
removed for cleaning or replacement. As used herein "stylus" means an 
instrument used for writing or marking. The structure and functioning of 
the stylus member may be better understood by referring to FIGS. 6 and 7, 
which are side and frontal view of the stylus respectively, in conjunction 
with FIG. 5. The stylus member 30 has a foot 32 with a notch 33 therein. 
The notch is oriented in the direction of motion of the elongated article, 
when the stylus is in its operative position. Preferably, the notch has 
cross-sectional dimensions such that the ridge 25 protruding from the 
surface of the elongated article may pass through the notch when the foot 
of the stylus member rests on the surface of the continuously moving 
elongated article, as shown in FIG. 5. Making a rough analogy, the 
tracking arm member and stylus member follow a ridge protruding from the 
surface of a constantly passing elongated article in a manner that is 
somewhat analogous to the way that a phonograph needle and tone arm follow 
the grooves on a phonograph record. However, in the case of a phonograph 
the needle rides between the ridges of a record disk, while in the present 
invention the ridge on the elongated article passes through the notch in 
the stylus member. The stylus member has a bore 34 therethrough, through 
which the marking fluid flows. The bore 34 has first 35 and second 36 
ends, with the first end of the bore communicating with the notch 33 in 
the foot of the stylus member, and having a cross-sectional width that is 
less than the cross-sectional width of the notch. Preferably, the bore 
through the stylus member is divided along its length into first 37 and 
second 38 portions, the first portion 37 including the first end 35 of the 
bore and having a smaller cross-sectional area than the second portion 38. 
The bore may be most conveniently made with a circular cross-section, and 
a working embodiment has been manufactured in which the first portion of 
the bore had a diameter of 1.07 mm (0.042 inches which is the diameter of 
a #58 twist drill), and the second portion of the bore had a diameter of 
4.78 mm (0.188 inches). The stylus member and tracking arm member may be 
manufactured using any suitable material such as metal or plastic, but 
they should be as light weight as possible to reduce the possibility of 
marring the surface of the article being marked upon. 
A reservoir 39, having an outlet 40 is used to store a supply of marking 
fluid. Preferably the reservoir is located higher than the stylus member 
30 such that gravitational force will cause the marking fluid to flow 
through a hollow tube 41 and then through the bore through the stylus 
member. It is convenient to locate a valve 42 at the reservoir outlet to 
stop the flow of marking fluid when the marking apparatus is not being 
used, and to control the rate of flow of the marking fluid. The hollow 
tube 41 has a pair of ends; one end communicating with the outlet of the 
reservoir, and the other end communicating with the second end of the bore 
through the stylus member. One or more clips 43 may be used to guide the 
hollow tube along the length of the tracking arm member. Preferably, the 
hollow tube comprises a material that does not react chemically with the 
marking fluid. The easy removal of the hollow tube for cleaning or 
replacement is felt to be an advantage over more complicated prior art 
marking devices. 
Of course, the physical properties of a marking fluid to be used with the 
marking apparatus of the invention are important. If the marking fluid is 
too thick, it may eventually clog up the bore through the stylus member, 
and may not flow at a smooth and steady rate. If the marking fluid is too 
thin, it may flow too quickly and run off of the protruding ridge onto the 
rest of the surface of the elongated article. It has been found that a 
marking fluid having a viscosity of between about 2,300 centipoise and 
about 3,300 centipoise, as measured by a Brookfield Viscometer, (spindle 
number 3, at 30 revolutions per minute) works satisfactorily with one 
embodiment of a marking apparatus manufactured according to the invention. 
While certain representative embodiments and details have been shown for 
purposes of illustrating the invention, it will be apparent to those 
skilled in the art that various changes and modifications may be made 
therein without departing from the spirit or scope of the invention.